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Apple and Lenovo#8217;s Technology Stratagy. The Technology Strategy Comparison of Lenovo and Apple MG 8673 Technology strategy Professor: Oded Nov Xiaofei Li Table of Contents Company Profile 3 Company Vision and harvard School, Misson 4 SWOT Analysis5 Porter’s Five Forces6 Product market matrix 7 Growth Share Matrix8 Technology operation of Lenovo and essay writing Pomfret School, Apple9 First Mover/Dominant design 9 Government regulation10 Lock-in and Switching Cost10 Strategy operation of Lenovo and Apple11 Conclusion12 Company Profile Lenovo is a Chinese multinational computer hardware and electronics company. Harvard Bussines International. The company was formed in China and incorporated in HK and would grow to be the largest PC company in Anglia Ruskin University China. And in 2005 Lenovo acquired the former Personal Computer Division of IBM. Its products include personal computers, tablet computers, mobile phones, workstations, servers, electronic storage devices, IT management software and smart televisions. Today, Lenovo is a US$21 billion personal technology company and the world’s second-largest PC vendor1, it has more than 26,000 employees in more than 60 countries serving customers in more than 160 countries2. Apple is an American multinational corporation, incorporated on 1977. It engaged in designing, manufacturing and marketing mobile communication and media devices, personal computers, and portable digital music players. Apple sells a range of iPhone, iPad, Mac and iPod compatible products, including a portfolio of consumer and professional software applications, the iOS and harvard review International of Milan, Mac OS X operating systems, iCloud, and a range of accessory, service and support offerings. Nursing. It also sells and bussines review of Milan, delivers digital content and applications through the iTunes Store, App Store, iBookstore, and Mac App Store. It aspires to achieve this goal by leading in three key areas: Personal Computers: Lead in PCs and be respected for its product innovation and critical thinking problem Durham, quality.
Convergence: Lead the industry with an harvard review International School of Milan ecosystem of devices, services, applications and content for how to write for an School people to seamlessly connect to harvard review School of Milan people and Web content. Culture: Become recognized as one of the best, most trusted and most well-respected companies to work for writing Les Roches School Management and do business with. 2 2. Harvard International Of Milan. Lenovo is building a way of about Les Roches International School Management viewing the world and doing business—it introduces the newest products in China and then spread across the globe. Lenovo believes that the new way of expansion from bussines East to West is the way of future 3. Lenovo’s business is built on product innovation, a highly efficient global supply chain and strong strategic execution. Solving Durham. The company develops, manufactures and markets reliable, high quality, secure and easy-to-use technology products and services for customers who want technology that does more. Apple Company’s vision and mission 1. Apple believes that they are on the face of the earth to make great products and that#8217;s not changing. They are constantly focusing on innovating.
They believe that we need to harvard bussines review School own and Anglia Ruskin (Navitas), control the harvard bussines, primary technologies behind the products that we make, and participate only in markets where they can make a significant contribution. 6 2. Apple is committed to protecting the environment, health and safety of their employees, customers and the global communities where they operate. They recognize that by integrating sound environmental, health and safety management practices into all aspects of problem their business, they can offer technologically innovative products and services while conserving and enhancing recourses for future generations. Apple strives for bussines review School continuous improvement in the environmental, health and safety management systems and in the environmental quality of their products, processes and services. 7 Lenovo Company SWOT Analysis Strengths | Weaknesses| * Mass and strong relationship with domestic mainland Chinese customer * Mass Manufacturing and low production cost. * Excellent marketing and distribution strategy. * Merge with IMB Personal Computer | * Mundane Outlook * Relative weak Global Brand Perception * Relative weak Online Sales * Not qualifies After-sales Services * Limited knowledge of global market| Opportunities | Threats| Chinese Government Association * Fast growing Personal Computer market * The neighbor hood Indian is becoming the fastest growing PC market in trip essay the world * Signing of memorandum of understanding with USA * Specialty shops providing one stop platform for distribution| * Appreciation of RMB will increase product price outside of Chinese market * Competition threats from local and international competitor * Price war * International competitors forming alliance with local competitors. * Industry Reaching Maturity| Apple Company SWOT Analysis Strengths | Weaknesses| Large segment of loyal customer called “ Apple fans” * Strong brand image. * Retail Stores provide the experience and eye –catching Apple product * Huge RD Innovation | * Patent infringement. * Product recalls. * Failure of Mac Mini and harvard of Milan, Apple TV * The fast speed of Pomfret changing product generation | Opportunities | Threats| * Strong growth in smartphone and personal computer industry. * Cooperation with other big company like Google coupled to create new innovation * Apple product lock in harvard International School customer behavior| * Rising popularity of Google Android. Market competition in PC and smartphone industry. About Article Les Roches International School. * Dependence on specific suppliers. Review School Of Milan. * The leadership after Steve Jobs| Porter#8217;s five forces for the companies industry New entrants, bargaining power of supplier, bargaining power of essay buyers, Substitute, Rivalry 1. Smartphone market share is harvard of Milan, basically covered by big cellphone manufacture company e. g. Apple, Lenovo, Samsung, HTC, Nokia, Blackberry. They have huge R;D innovation, large based and loyalty customer, excellent marketing and advertising strategy.
The new entrants are limited in this market, and they are rarely to journals University (Navitas) survive. . This case is the same in Tablet and PC industry. This entrants are also hard to get into this market, because the harvard review, market share are occupied by those big company such as Apple, Lenovo, Netflix, Samsung, IBM, Dell, HP, Sony. 3. Lenovo and Apple make the product outsource to the supplier such Foxconn. Article Writing Management. But basically suppliers have relatively weak bargaining power with Lenovo and Apple, because Apple and Lenovo odder huge numbers of electronical products from the suppliers, they stand in a relative strong side in the bargaining table. 4. Even though the competition in the smartphone, Tablet and PC industry is harvard School of Milan, toughly intense, those markets are fundamentally regulated.
When a product is Anglia University, put onto market, the price is fixed. But customers have some bargaining power eg the old generation always cut down price for customer when new generation go in. to market. 5. Smartphone, Tablet and PC products all have substitute. 6. Harvard. Lenovo and Apple face strong competition and they have so many rivals in each of their product line eg Microsoft, Sony, HTC, Samsung. Product market matrix Product| Present| New| Market| Present| Market Penetration| Product development| | New| MarketDevelopment| Diversification| In product market matrix, Lenovo and Apple product are both in a present market and their product are basically present, so the majority of their product are in the market penetration place. Meanwhile, for some product like when Steve Jobs launch the iPad in 2010, it was a breakthrough in the tablet PC industry. So in some cases some Lenovo and Apple products in some specific time are in the product development place. Growth share matrix Star| Question Mark| Cash Cow| Dog| High Share Low Share. High Growth Low Growth Because there is obvious potential growing trend in books essay writing the smartphone, PC, notebook and tablet industries, meanwhile Lenovo and Apple both have high market share, so in the growth share matrix, they are both STAR companies. Harvard Review. Technology Operation Products Comparison| Apple Product| Lenovo Product| PhoneIphone VSLephone| | | NotebookMacbook Pro VSThinkpad| | | Tablet Ipad VSIdeaTab| | | DesktopMacVSIdeaCenter| | | TVApple TVVSLeTV| | | NotebookMacbook Air VSIdeaPad| | | First Mover/Dominant Design For apple product, the first market dominant design is the iPod.
Since October 2004, the critical thinking University, iPod line has dominated digital music player sales in the United States, with over 90% of the market for review of Milan hard drive-based players and over 70% of the market for all types of players. Article International School Of Hotel Management. 8 The second Apple dominant design product is harvard International School of Milan, Ipad. When Steve Jobs released the Ipad on April3, 2010, Apple sold more than 15 million first-generation Ipad prior to the launch of the article writing Les Roches International of Hotel Management, IPad 2—selling more than all other tablet PCs combined since the IPad#8217;s release, and reaching 75% of bussines review International of Milan tablet PC sales at essay Limkokwing the end of harvard International of Milan 2010. 9 Meanwhile Lenovo is the dominant design in the computers supplier area in Mainland China, with a 28. Writing Limkokwing University. % share of the Chinese market. It reported annual sales of $14. Harvard Review School Of Milan. 9 billion for the fiscal year ending 2008/2009. 10 In October 2012, Lenovo ousts HP became the world#8217;s top supplier of personal computers.
In the third quarter of 2013, Lenovo shipped 13. 77million units, giving it a 15. 7% share of the global market, compared with HP, which enjoyed a 15. 5% share with 13. 55 million units. Article Writing Les Roches Of Hotel Management. 11 * Government regulation As far as now, there is no government regulation for harvard review International School Lenovo and Apple because the government thinks this market is School, relative fair of compete and regulate. Lock In and Switching Cost In lock in customer strategy, Apple is the master, It makes customer realize that once use the apple product, it is extremely hard to find the exit. Apple creates iTunes, App Store, iCloud and OS system to make this strategy into bussines review, fully used.
Simply speaking, you purchase music, movie in Anglia Ruskin (Navitas) iTunes, purchase apps in App Store and restore/backup photos, music, documents, applications in iCloud. When apple launch a new generation iphone, the customer can simply use the harvard bussines review International of Milan, iCloud and iTunes to restore everything from their last generation iphone. About Article Writing Les Roches International Of Hotel Management. And when customer creates a reminder in the mac, it will automatically show on their Iphone and Ipad. Bussines International Of Milan. Since the iCloud only Anglia, works on Apple product, so this strategy will lock in customer on apple product, and deepen the switching cost if someone wants to change to another company product. Harvard Bussines Review International School Of Milan. Since apple’s information technology products work in writing system, so switching any single product is International, costly. Also Lenovo is currently trying to lock in School its customer launch the same storage technology called Lenovo Cloud, the user can back up and sync data from multiple Lenovo devices including LePhone, LePad, and LeTV using a 200 GB online storage. This strategy is to tie the Lenovo tablets and devices together and make the customers feel that switching away would cause too much hassle. Strategy Operation Lenovo For Lenovo their operation strategy is consolidate its market in China and expand its market out of China. Review International Of Milan. Lenovo has its headquarter both in Beijing and in United States. They are the leader in China with more than 30 percent market share in PCs, and their product sales in reviewed China account for 46 percent of global sales. So with builds on its dominant position in China to grow globally, it plans to bussines review School have rapid growth in emerging markets and a unique global footprint.
In 2012, Lenovo partially moved production of its ThinkPad line of computers to Japan. 12 In October 2012, Lenovo announced that it would start manufacturing computers in Whitsett, North Carolina. 13 In the marketing strategy, based on different levels of consumers, Lenovo developed different prices, by creating differentiated products to meet different consumer groups. And this strategy is critical problem solving University, Middle and High End Market Positioning. Take Lenovo’s personal computer as example, the of Milan, market survey shows that its refrigerators mainly focus on middle and high end, Lenovo owns 70% market share in high end products, while the middle end count for 40—50% market share, the market share of low end product is lower than 10%. 14 As for the supermarket channel, Lenovo has designed relatively low prices of mid-level products, while high-end products on the electrical chain and retail sales channels. For the rural market, Lenovo designs and develops products that have relatively simple functions, relatively low prices to writing Management meet the need of the students market.
Apple For Apple, people would doubt their operation strategy after the past of harvard bussines review of Milan their hero leader Steve Jobs, who is the pioneer of Apple. But the nursing Seneca, new leader Cook operates the company quite well. In cook’s first 16 months on the job, Apple has released next-generation iPhones and iPads and seen its stock price rise 43 percent. 15 As is the same with Lenovo, Apple also put a lot of concentration in the Chinese market. With a population of 1. School. 3 billion, China is the about article Les Roches International Management, world#8217;s largest mobile market and already Apple#8217;s second biggest market overall. Apple currently sells its iPhone exclusively through China Unicom with 196 million subscribers. The Apple current CEO Tim Cook visited Mainland China and harvard bussines International School of Milan, its supplier Foxcoon In March 2012.
And this is the first Apple CEO to visit China, as Apple is ramping up its investment in the world#8217;s most populous market. Also for Apple, their operation strategy is to make the greatest, most innovation and most simple product in the world, but Apple not only focus on the technology innovation, they focus on nursing essay College, the global environment and human right. Apple reports environmental impact comprehensively. Bussines International. They care about the total carbon footprint in the manufacturing and transportation process, also in product use, recycling and facilities. Meanwhile Apple is committed to how to write for an essay The Windsor School the highest standards of social responsibility across the worldwide supply chain. They provide safe working conditions, treat workers with dignity and respect, and use environmentally responsible manufacturing processes to the supplier such as Foxconn in China. 2 Conclusion To sum up, Lenovo and Apple operate in the same environment.
They both focus on the smartphone, desktop, notebook, tablet and future TV industry. Of Milan. Since their backgrounds are different, they operation strategies are different. Lenovo is based on Chinese market and then spread its product around the how to for an, world. The product has low prices of mid-level products, while high-end products on the electrical chain and retail sales channels. Meanwhile Lenovo plans to further explore its market in Japan and harvard review International School, US. In the contrast, Apple has a huge US and global market, their price always lead the writing School of Hotel Management, market. Right now it plans to further explore its business in China, for bussines International School of Milan it is the world#8217;s most popular market. It is sure that Lenovo and Apple will have fierce competition in the future market. Reference 1http://www. marketwatch. com/story/lenovo-passes-dell-to-become-worlds-no-2-pc-maker-2011-10-13 2 http://www. lenovo. com/lenovo/us/en/our_company. html 3http://appleinsider. Solving Durham University. com/articles/08/10/21/apple_iphone_3g_sales_surpass_rims_blackberry. html 4 http://www. apple. Bussines Review International School Of Milan. com/retail/storelist/ 5http://www. sec. gov/Archives/edgar/data/320193/000119312512444068/d411355d10k. htm 6http://alvinalexander. com/blog/post/mac-os-x/apple-business-philosophy-mission-statement 7http://www. Critical Problem. apple. com/environment/ http://www. apple. Review International School. com/pr/library/2009/01/21Apple-Reports-First-Quarter-Results. Essay Writing. html 9http://www. Harvard Bussines International. economist. Trip Limkokwing. com/blogs/dailychart/2011/03/tablet_computers 10http://www. reuters. com/article/2012/02/09/markets-hongkong-stocks-preopen-idUSL4E8D87B720120209 11http://www. bbc. co. uk/news/business-19906119 12http://www. gizmochina. com/2012/08/29/lenovo-moves-thinkpad-production-to-japan/ 13 http://news. lenovo. com/article_display. cfm? article_id=1635 14 http://www. jgbm. org/page/19%20Wang%20Wen%20Cheng%20. pdf 15http://www. workingwider. com/strategic_innovation/apple-business-strategy-2012/ Haven’t found what you want?
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Ladder Logic Examples and PLC Programming Examples. I will start this article by making a confession: When I develop a PLC program, I steal other people’s ladder logic. I am stealing ladder logic examples for inspiration and harvard School, solutions to my PLC programs. From time to time you will be facing the same problem, when you do PLC programming with ladder logic. By looking at examples of ladder logic programs, you will be able to find a solution to your problem very fast. You may even find a smarter solution in the ladder logic examples than your own solution. There are several reasons to use examples of PLC ladder logic. Essay Seneca College! You can skip those and go straight to the PLC program examples:
Why Use PLC Ladder Logic Examples? The reason I use ladder logic examples is one of the big advantages of code. In this case the PLC programming language ladder logic. You can reuse chunks of a PLC program in your own PLC program. Bussines Review International Of Milan! You can “copy and paste” lines of ladder logic symbols from one PLC program to another PLC program. By doing so, you will shorten the development time of a project. So that you don’t have to invent everything from the write essay School, very bottom each time you are developing a new PLC program. Harvard Review International School! That is why I often make use of PLC program examples. If you want to learn ladder logic from the International of Hotel, beginning, you should check out harvard International School of Milan, my ladder logic tutorial! Learn from PLC Programming Examples.
Another reason to make use of ladder logic examples is, that you can learn from them. Let’s say you have a specific functionality, you want to implement in your ladder logic. The first thing you naturally would do, is to think about it for yourself. Try to design the books writing Pomfret School, ladder logic by yourself. But even though you come to a solution, there might be a smarter way to make that piece of ladder logic. Harvard! When you look at how to essay The Windsor School a ladder logic example it may look different from your ladder logic. This is due to the fact that every function you want to implement in harvard bussines International, your PLC program, there are many different solutions.
Ladder logic examples can be hard to find, though. Especially because the names of the ladder logic examples often are confusing and critical solving Durham, even misguiding. A ladder logic example of harvard review School a trafic light can, as an example, vary a lot. One other thing that causes good PLC ladder logic examples to be so hard to find, is that ladder logic often is brand specific. Many PLC ladder logic program examples are available for download, and you will have to install the PLC programming software to view the example ladder. Another brand specific issue is the names for the instructions and functions. For example in the Siemens S7-1200 and other PLC’s from Siemens the latching function is referred to as the set/reset function. While that function, in Allen Bradley PLCs, are the called latch/unlatch function. You can start exploring the latch/unlatch function already now with RSLogix Micro Starter Lite from Allen Bradley.
Learn ladder logic PLC programming with Udemy. Collecting the Best PLC Programming Examples. For those reasons I have made this collection of how to write for an PLC ladder logic examples. I have divided all the ladder examples into harvard bussines review of Milan categories, so you can find them with ease. Trip Essay Limkokwing University! The first examples are general ladder logic examples. These examples can be used in almost every ladder logic PLC program. If you need a simple function implemented in your ladder logic, you can use the general examples.
General ladder logic examples can almost always be copied into your own ladder diagrams. The only review International thing you need to edit, is the names and the symbols for the bit logic instructions. At last you will find real-world PLC ladder logic examples. This is writing Seneca a collection of PLC programs from the real-world, where simulations, videos or photos are a part of the example. Real-world PLC examples from a factory or a traffic light can be very useful, when you are searching for inspiration. These examples can rarely be copied to fit your own project, but you can use chunks and harvard International School, ideas from the real-world examples. Do you have your own PLC ladder logic examples, even better than these?
I will gladly put your PLC ladder logic example on this site. In that way, we can all benefit from this list of the best examples of PLC ladder logic. Ladder Logic Examples and Example PLC Programs. Click on the type of PLC program example you want to Anglia Ruskin University (Navitas), see, or scroll down to see the all: Simple Ladder Logic Program Examples. Ladder diagram examples and harvard bussines International of Milan, solutions to simple PLC logic functions. These are all basic PLC functions implemented in ladder logic. Simple Start/Stop Ladder Logic Relay. This is how the ladder diagram looks for journals University (Navitas) a simple start/stop function.
The function can be used to harvard bussines review School, start and stop anything like a motor start/stop. In this ladder logic example, there are two inputs. The start button will activate the relay, or ladder logic relay M10.0. When the Anglia (Navitas), start button is released, the relay will still be activated, because of the latch in International, ladder rung 2. This latching will be broken when the stop button is how to write for an essay The Windsor activated. You might wonder why the stop button in this example is normally open. Bussines Review International! And the reason for that, is that y ou should use normally closed as stop button, to avoid dangerous situations under failure. Here is reviewed University what the PLC program example looks like:
Simple ladder logic examples of start/stop of relay. Single Push Button On/Off Ladder Logic. This function is harvard School also called push on trip essay writing Limkokwing, push off logic sometimes even flip-flop or toggle function . It is the same function as the on/off button on your computer or mobile phone. When you push the button the first time, the output will be activated. Now, when you push the review School, button for the second time, the a conclusion The Windsor School, output will deactivate and turn off.
The single push button has two functions: on and off. Push on push off logic can be done in review School of Milan, several ways. It can be done by reviewed University (Navitas) using ladder logic and boolean logic instructions or it can be done with a counter. It can even be done with PLC rising edge and falling edge triggers or with shift registers. Here is the example using boolean logic instructions only (complicated version): Single push button ON/OFF ladder logic example.
Also known as “push to on, push to off” logic function. This example is from the PLC, Scada, DCS blog. The blog has a lot of very useful information about PLC programming and especially ladder logic. Take a look at the blog and review School, see the trip writing Limkokwing University, many ladder logic examples. But… there is a faster way to make the same toggle function with a single push button:
The example is from Mayur Haldankar’s blog about International School PLC programming and DSP (digital signal processing). He even has examples of DSP programs written in about article writing of Hotel Management, C++. In his example, he uses 3 (4) rungs only to make the toggle function of a push button (simple version): Ladder toggle or flip-flop function (single push button on/off). Ladder Logic Examples with Timers. PLC program examples with timers in ladder logic.
Generally speaking, you have three types of timers available in ladder logic. Harvard Bussines Review International School Of Milan! The on-delay timer, the off-delay timer and writing College, the retentive timer. PLC Program Example with On Delay Timer. The first type of timer in ladder logic is the on delay timer. Its name comes from the fact, that the on delay timer delays its output from the on signal. As soon as the on delay timer gets a signal at harvard bussines International School the input , the timer starts to count down. When the preset time is up, the output of the on delay timer will turn on. If the input is turned off before the count down finish, the time will reset. On delay timers in ladder logic can look different depending on how to a conclusion School, the PLC programming software. But common for all of them are the harvard bussines International, following: The enable output (EN) is the first output and essay writing Seneca, it is on when the timer is energized.
So, as long as the input is true or on, the enable output will be true. Second output is the done output (DN). This output in an on delay timer is only on, when the bussines review, timer has counted down the preset time. Look at this great video for more info about the on delay timer. The software used is the free RSLogic Micro Starter Lite from Allen Bradley. PLC Program Example with Off Delay Timer.
The off delay timer works just like the on delay timer with one exception. Instead of starting the count down from the signal at the input turns on, the off delay timer starts to how to essay School, count down from the bussines review School of Milan, signal turning off at the input signal. The example below is from essay writing Limkokwing Sakshat Virtual Labs. In the example, ladder logic is used to visualize the harvard bussines review International, values of the three bits in an off delay timer. These three bits are from Allen Bradley PLCs, but other brands has similar bits. Enable bit (EN) – On when the timer is energized (input is on) Done bit (DN) – On when the write a conclusion, timer is done counting down Timer timing bit (TT) – On when the timer is counting. Cooling Example With Off Delay Timer. Another example with the use of the off delay timer in ladder logic is in heating. Bussines Review International School Of Milan! When you are heating something, you often have some sort of cooling too. About Article International School Management! A good example of that is a heating oven. The oven is heated by an electrical heater, and in harvard bussines International, the side there are ventilation motors to writing, cool the oven after use.
Here is a simplification of how the cooling PLC program should work: Heating element and cooling fans turn on. HEATING OFF: Heating element off and harvard bussines School of Milan, off delay timer starts counting down. TIMER DONE: The electrical heater and the cooling fans should turn on simultaneously.
Why the essay writing College, cooling fans has to turn on too, is to circulate the hot air and spread the harvard bussines review School of Milan, heat. Since both the fans and the heater has to start at article writing Les Roches International School of Hotel Management the same time, the harvard International School, two outputs should work simultaneously. Trip Essay Limkokwing! But keep in mind, that the cooling fans has to run for some time, after the heater is turned off. This is the exact function of an off delay timer, and the ladder logic example looks like this: Example of motors with cooling in bussines International School of Milan, ladder logic. Off delay timer for extra delay. PLC Program Example with Retentive Timer. Retentive timers are just like on delay and off delay timers, but with one crucial exception. The time only nursing essay writing Seneca College pauses if the input is turned off before the harvard bussines International School, count down is writing finished. When the input is turned on again, the timer continues counting down from where the bussines review International School of Milan, time was paused.
The word retentive even means to retain, and that is what retentive timers do. Reviewed Journals University (Navitas)! They retain the time they have counted when the input is off. If you’re still not sure, check out this video of a functioning retentive timer in ladder logic: KronoTech has published a very informative PLC program example. Bussines Review School! With the Ruskin (Navitas), use of bussines review of Milan a retentive timer to control a motor with an automatic lubrication system, they have made a great practical example. More About Timers In PLC Programming Examples. Feel free to watch this video for more information about essay Pomfret School PLC timers in ladder logic. Harvard Bussines School Of Milan! The video illustrates some great examples and the basics of PLC timers. The PLC programming software used is RSLogix 500.
Motor control can be done with a PLC program. In fact, the PLC is about article writing Les Roches International of Hotel Management a common choice for bussines review controlling AC motors. Here are some examples of ladder diagrams for motor control. One of the most common ways to start an AC motor is by first starting the motor in star connection. When the journals University, motor speed is sufficient, the connection is switched to delta. This is due to the high current AC motors use when starting. Star/delta motor control can be done in several ways. Harvard Bussines Review School! To switch between the star and the delta relay, a timer is used. The ladder logic for a star/delta motor control is nursing quite simple, and that is one of the advantages of using a PLC for motor control. Another great example of how to bussines review International School of Milan, use a PLC for star/delta start of an AC motor is essay writing example #5 in the PDF file below.
It includes a lot explination and harvard bussines International, a lot of Les Roches International School of Hotel Management great power and control circuit diagrams. Example #5 is on bussines review, page 30. Ladder Diagram for DOL Direct On Line Motor Starter. Still commonly used in many factories the DOL or direct on line motor starter is another way of starting AC motors. The DOL is made of a contactor (usually 3-phase contactor), an overload relay like the thermal relay, and some connections in between. Controlling the DOL motor starter with a PLC program is simple. This video below shows an example of how to control a DOL with a PLC program.
In the example the how to write for an essay The Windsor School, PLC Zelio from Schneider Electric is used. But any PLC with digital inputs and outputs can be used, even the mini PLC Siemens S7-200 or the review International School of Milan, later Siemens S7-1200. Sometimes you might have to use a smaller relay between the PLC output and the coil of the contactor. Make sure you always check the ratings of the PLC outputs you are using. PLC Program Examples From The Real World. These next PLC programs are examples of real-world PLC applications. All examples of how to use PLC programming and ladder logic to solve real problems. Traffic Light Ladder Logic Diagram. One of the most used applications for a PLC is the traffic lights.
At many schools, universities and even companies you will get the challenge to make a traffic light ladder logic diagram. The traffic light PLC program is nursing essay a combination of timers to harvard bussines International of Milan, control which lights are turned on and for International of Hotel Management how long time. Review Of Milan! But some sort of interlock must be there to prevent the green light to be on in multiple directions. A PLC program like the traffic light is Limkokwing a little more complicated and therefore are a lot more solutions to. Bussines Review International! For inspiration you can look at these good examples of critical University traffic light ladder diagrams: The first ladder logic example is from Engineer On A Disk, which is a marvelous site full of great articles. In the example you will get all the ladder diagrams and step-by-step instructions and explanation. If you are using LogixPro Simulator, then you should absolutely take a look at this great example video: Ladder Diagram for Bottle Filling Plant.
Detailed example from Electrical Engineering Portal. Review International Of Milan! This is writing School a great example because of all the explanation it gives. You will be introduced to the actuators (motors), sensors and harvard bussines review of Milan, switches and Seneca College, a step-by-step guide to how to make the PLC program. At last you will see the example ladder logic for the bottle filling application. If you are using LogixPro Simulator from Allen Bradley, then you can learn a lot from this example video: PLC Ladder Diagram for Elevator Control. Elevators are often controlled by a PLC or a similar controller (sometimes even relay controllers). In fact a PLC program is bussines School of Milan a great way to make an elevator control. But before you start looking at ladder diagrams and PLC program examples for elevator control, some safety issues are important to know about. Here are the things you need to know before you start to trip essay, build a PLC elevator control: No elevator control without mechanical parts.
All these parts has to be tested and harvard International, verified to about article writing of Hotel, make sure that they will last. Electrical safety. Be sure to bussines review of Milan, follow the rules and regulations for electrical safety. Nursing Essay! They differ a bit depending on whether you are in the US, Europe, Asia or anywhere in harvard bussines review International of Milan, the World. This includes proper grounding, using the Pomfret, right circuit breakers, wire gauges and so on. PLC elevator program safety. The last but not least part is the PLC elevator program.
In the bussines International School of Milan, elevator examples you will be looking at, there will be a lot of interlocks, to how to write a conclusion for an The Windsor, prevent some functions to run at the same time. This is a highly critical point. For example, you don’t want to elevator to run before the doors are closed! This is a great introduction to how the elevator control system works: And here is an example of a ladder diagram for bussines International School elevator control from circuit4hobby: Did these example PLC programs help you? Rate this article below or write a comment if you found this article helpful or you have any questions. If you would like to share your ladder logic examples, please write a comment below or send me a message. You can also find us on Facebook. Pls send more stuff on PLC project examples.
how to write a overlap programme.. i mean ,there are two programmes in plc,but its run separately… USE SELECTOR SWITCH IN OFF CONDITION PROGRAM 1 WORKING AND IN ON CONDITION PROGRAM 2 WORKING. how to thinking University, make ladder logic from flow chart?? hello everyone,i am a first year student at CPUT doing electrical engineering,we have been given a project about on/off controller using PLC,my problem i never used PLC before and i don’t even know how they work. can someone plz explain to me how does it work? I been using Plcs for over 20 yrs.. Once you know it its very easy. I still watch all videos on youtube.
Type in ladiesandtech.com good place to start. i want to learn about delta plc. hi guys…whr can I get a plc software for a laptop…without necessarily buying online. you have one choice download delta plc software its free. and then practice on bussines School, it . this the only softwtwar eits free on web site. and about Les Roches International Management, it easy to learn. if u have want any plc program. Harvard Bussines! mail i can make program. mail me your details. i will teach you how to learn. can you please help me to learn how analog outputs are used in delta. single push button controls output on/off. Would like to attatend lessons on ladder logics and plcs. i need digital watch ladder diagram.
How i’m build water level indication logic. give me idea for how to write for an ladder program. ladder diagram for 3motors 3timers. How to make a ladder diagram for oil and harvard bussines International School, gas tank level? Using PID controller, AUTOMATICALLY. How to make a ladder diagram for about article International of Hotel oil and gas tank level?
Using PID controller, AUTOMATICALLY. I want to need more examples of omron plc Twido Delta. what types of harvard International School sensor you used in lighting system. principle aperation of lighting of using plc. Hey guys… I have to program the “Batching Process” on ITS PLC,using Automgen, but i find it to be very complicated… Can anyone help me,please? is there a software to draw plc ladder diagrams??
when I run S7 pro I need to test my program ,PLC simulation on/off button is disabled. How to enable this button in essay School, manager? Design PLC program of One coil on/off by bussines International of Milan one push button.. Thanks for Limkokwing University these examples and we hope more specially for automation in industrial process. thank you for giving example of plc programming . i need more example plz send my e-mail id. i want ladder ladder prgm to count 0-100 100-0 up-down counter using single push button . its continuous operation. Awesome.
Thank you so much for International of Milan this. You should start a paypal.me/yourname account and let people buy you a cup of coffee or donate to the cause! it is a good site abuot plc training, thank you for giving example of plc programming . i need more example plz send my e-mail id. Thank you for giving example of plc programming . i need more example please send my e-mail id. I’m looking for anything dealing with studio 5000 and how to write a conclusion for an essay The Windsor School, servo motor drive interface. We use Parker drives.
I have to coordinate a sequence of motors to flow at one speed with the ability to harvard review School of Milan, draft. hi i need a V/F open loop control on plc ladder logic program please send a model of plc on my mail id. write a program to find frequency of given signal (analog) this question was given by my teacher and Im curious to know about ladder program. It would be very helpful if you can guide me in this. There is a huge programming error. Single Push Button On/Off Ladder Logic. “Here is the example using boolean logic instructions only Anglia Ruskin University (complicated version):” under this complicated version, Extend M0.1 and bussines International of Milan, M0.2 on rungs 4,7 past the thinking problem solving Durham, Push Button…. | M0.0 I0.0 M0.2 M0.1 | Then do the same for rung 7…. It will not latch right and the second Press will never activate.
-The keyboard cowboy. Well the post removed my spaces, in the last post. UGH… Copy and paste this into notepad, Then Replace * with a single space for the edit…. I want to know about rise/fall edge trigger switch working. My name is Mr. Harvard Review International Of Milan! Claudiu Adascalitei, and i’m a student of trip University University from Sibiu city, Romania. Review International! So, I want to help me with a project for school. It’s about essay writing University a ladder diagram programming. Can you help me, please. I send my adress e-mail to contact: email@example.com.
it is bussines International rely good for bigginer. Hi I am new for PLC,,I start learning from today of PLC ladder programming..I hope it will help me like a near teacher…. It’s so simple and easily to understand the stuff,but need some more diagram to practice in order to master the process. I am having a hard time trying to figure out a simple logic issue. Can you please draw me or explain the trip essay writing Limkokwing, logic for:
SW1 turns on a green pilot light. SW2 turns on a red pilot light. When both SW1 and SW2 are pushed, a white pilot light only comes on. S1 AND NOT S2 = GREEN LIGHT. S2 AND NOT S1 = RED LIGHT. S1 AND S2 = WHITE LIGHT. I want a plc program for magnet cranes.
guys does anybody know about textile industry ladder logic and how they work?? i need to write code for in ladder for a task with a conveyor with three color sencor and tree bin so when a bin is full the conveyor is stop the first color sensor is alone and review School, it is at begin the write School, second two is next to it and below them are the bin in the end of the bussines of Milan, conveyor are the red bin . we put object on the conveyor one each time . is anyone can help in ladder (brandley ) Everyday I'm exploring the world of PLC programming to find better solutions for trip writing automation. I believe everybody can become a PLC programmer with the right learning materials. My goal with PLC Academy is to help you learn PLC programming.
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Tabs configuration, extracted from About:config entries. This page was created to be a companion of my page on Tabbed Browsing in Firefox. The table on this page consisting of selected tab and window items has been extracted from http://kb.mozillazine.org/About:config_entries. This listing is basically comprised of entries selected from the mozillaZine article About:config entries http://kb.mozillazine.org/About:config_entries dealing with tabs and is mainly from the following groups: To view table and your own settings at the same time, you might want to install the bussines School of Milan, Split Browser extension and split the screen vertically with the table as the main at the bottom so it is with Find, and reviewed journals Ruskin (Navitas) with the split about:config at the top, and descriptions such as on this page below. (for more information see firefox.htm page) Note: Spaces between the review School of Milan, dots in preference names exist purely for about Les Roches International School of Hotel word-wrapping . They are actually not present and should not be thought as so. To find values related to an about:config configuration entries Type about:config into the location bar. The next thing that you might do is use the filter at bussines International of Milan the top of the about:config page to writing, type/paste in a configuration name, or part of a configuration name. Using part of bussines review a name can help spot related configuration entries. For example -- filter: opentab You can use wildcards (and RegExpr) in nursing Seneca, filters (Bug: 213832), so many could be picked up with filter: browser*tab. Use your browser's FIND to find variables or descriptions matching a one word or character string.
For instance you might want to use FIND openintab in browser, and filter: openintab in the about:config list where browser.search.openintab has extra spaces as browser. search. openintab. To change a configuration setting double-click on the variable and change the harvard bussines International, value (right-click context menu also works). If the type is Boolean a double-click will toggle the value immediately, so always keep an reviewed Anglia Ruskin (Navitas), eye on the value or the user set / default indication for each variable. number rows Click once on the bookmarklet at review International the left to thinking solving Durham, Number the bussines School, rows of each table . Details of critical thinking problem Durham Text and Data Bookmarklets at squarefree.com also see my Keyword shortcuts page to invoke bookmarklets on any page. 0 : Goes back in history. 1 : Acts as Page Up.
2 (and above): Does nothing. Note: See bug 301248 (Mozilla Suite) False : Links with target set to _blank will open in a new window. Note: No longer in use. Use browser.link.open_newwindow instead. False (default): Display the focus ring on links only. 0 : Hide focus ring. 1 (default): Dots around focused elements will be displayed with a 1 pixel border. (n) : Display dots with a width of n pixels around focused elements. False (default): Do not set colors on harvard International School of Milan, focused items. 0 : No toolbar and tab strip animation.
1 (default): Animates only article School of Hotel Management first collapse. 2 : Animates each collapse. True (default): Shows toolbar and bussines School of Milan tab strip. False : Hides toolbar and how to write a conclusion for an essay tab strip. 2 : Opens external links in a new window.
3 : Opens external links in a new tab. 1 (or anything else) (default): Opens external links in current window. Note: In Firefox 1.5, this can be changed via Tools → Options → Advanced → Tabbed Browsing → Open links from other applications in: This option is mentioned under Browser Behavior in harvard review International School, Firefox Help: Tips Tricks. Possibly removed in essay University, Firefox 3.1 see bug: 324164. 2 : In a new window. 3 (default): In a new tab. 1 (or anything else): In the bussines review International School of Milan, current window.
If you foolishly installed Tab Mix Plus then controlled by extensions.tabmix.opentabfor.search. False (default): Opposite of the above. Note: Firefox 1.5 and above only. Note: Firefox 1.5 and harvard bussines review School above only. False : Disable the Session Restore service completely. * For the write a conclusion essay The Windsor, browser session to be restored at startup after a crash, browser.sessionstore.resume_from_crash must be true.
* For the browser session to be restored at startup normally, browser.startup.page must be 3. True (default): Restore the previous session when the review International School of Milan, browser starts after a crash. False : Do not restore the previous session. * browser.sessionstore.enabled must be true for trip essay writing Limkokwing University this preference to International School of Milan, have an trip essay University, effect. In SeaMonkey (or at least in SeaMonkey 2 and above), this is the URL of your first or only homepage tab.
If you have a multitab homepage, additional URLs are in browser.startup.homepage.1, browser.startup.homepage.2, etc. Note: This can be changed in Firefox via Tools → Options → Main (Firefox 1.5 and 1.0.x: General) → Homepage and in harvard School, SeaMonkey via Edit → Preferences → Browser → Home Page. 0 : Start with a blank page (about:blank). 1 : (default) Start with the web page(s) defined as the home page(s). 2 : Load the last visited page. 3 : Resume the previous browser session (Firefox only, implemented after Firefox 2 beta 1) True (default): Hide the tab bar.
False : Always show the tab bar. Note: In Firefox, this can be changed via Tools → Options → Tabs → Always show the nursing writing Seneca, tab bar. (Firefox 2 and bussines School of Milan above) or Tools → Options → Tabs → Hide the tab bar when only one web site is open ( Firefox 1.5 ). 0: Display a close button on the active tab only. 1: (default) Display a close button on each tab. 2: Don't display any close buttons. 3: Display a single close button at the end of the tab bar (Firefox 1.x behavior) You will have to critical, install an extension like Tabs closebutton restored in order to continue using these options in bussines review of Milan, Fx31 and books Pomfret School thereafter.
Associated bug comments were cut off, heaven help users in finding solutions to stupid artificially created problems. Bug 865826, Bug 1001871 see Fx31 problems and the many bad user interface changes since Fx2, and all the time experienced users have to waste to harvard bussines review International, maintain a viable Firefox. True: Close window when closing last tab (default) False: Do not close the window when closing last tab (pre Firefox 3.5 behavior) Note: Changing to False prevents Firefox from how to for an essay The Windsor, closing the window when you close the last tab such as with Ctrl+W, and subsequently from closing Firefox itself when closing the bussines review International of Milan, last tab of the last Firefox window. True : Hide the tab bar. False : Show tab bar normally. Note: This is writing International Management not used to harvard review School, enable/disable the tab bar. How To Essay. It's used internally to decide whether or not to harvard review International School, show the tabbed bar.
True : When you open a bookmark in a new tab then that tab will load in the background without taking focus from the current tab. False (default): When you open a bookmark in nursing essay College, a new tab then that tab will become the current tab. Note: you likely want to harvard bussines of Milan, set this to same setting value as used in essay Limkokwing University, browser.tabs.loadInBackground (Bug 469456) Note: Firefox 1.0.x had a Tabs option for Select New Tabs from Bookmarks or History True : Load the new tab in the background, leaving focus on the current tab. False (default): Load the new tab in bussines review, the foreground, taking the books essay writing Pomfret School, focus from the current tab.
Note: Setting this preference to True will still bring the browser to the front when opening links from outside the harvard bussines International of Milan, browser. Note: target=_new creates/reuses a window named _new and is frequently used by Google. target=_blank loads the how to for an, designated document in a new, unnamed window [ ]. False : Existing tabs will be preserved when loading a folder of bookmarks. Harvard Bussines Review Of Milan. The bookmark pages will be loaded in tabs that are appended to essay Limkokwing, the current tabs. Bug 175124 - improve open in School, tabs behaviour,
1 (default): Replace current tab set with group. Note: Mozilla Suite/ SeaMonkey only. True (default): Do not focus new tabs opened from links (load in background) False : Opposite of journals Anglia (Navitas) above. Note: bookmarks history can be opened similarly with browser.tabs.loadBookmarksInBackground. Note: In Firefox, this can be changed via Tools → Options → Tabs → When I open a link in harvard bussines of Milan, a new tab, switch to how to essay The Windsor, it immediately ( Firefox 2 and above ) -1 : Browser startup page. 0 (default): Blank page. 2 : Last visited page. Note: Does not work in harvard review International, Firefox (see bug 269664 ).
True (default): Opens link in new tab. False : Opens link in trip essay University, new window. MenuEditor extension and Tab related extensions might remove control of bussines International School of Milan Middle-click, since I don't use Firefox's middle-click -- can't tell whether true or not. Note: Firefox 1.5 and Ruskin University (Navitas) above only. Determines the behavior of pressing Enter in the address bar or clicking the Go button. True (default): Open URL in new tab. False : Open URL in current tab. True - If new windows are diverted into bussines School of Milan new tabs and journals Anglia Ruskin University a resulting tab is closed, shift focus back to the tab that opened it. (Default)
False - When any tab is closed, shift focus to the adjacent right tab if it exists; otherwise, to the adjacent left tab. True : Show Force links that open in new windows to open in. options under Tools → Options → Advanced → Tabbed Browsing False (default): Opposite of harvard bussines International School above. False : No warnings will be given when closing the browser with more than one tab. Note: In Firefox, this can be changed via Tools → Options → Tabs → Warn (me) when closing multiple tabs ( Firefox 1.5 and above ) or Tools → Options → Advanced → Tabbed Browsing → Warn when closing multiple tabs ( Firefox 1.0.x ) False : Opposite of the above. Possible values and their effects. True (default): Display a dialog before quitting, warning that all windows will be closed. False : Do not require confirmation from the user when quitting. Caveats - If browser.tabs.warnOnClose is false, then this preference has no effect. False Do not require confirmation from the user when restarting. UI A checkbox labeled “Do not ask next time” appears on the confirmation dialog; when checked, this preference is toggled to false.
-1 : Browser Startup Page. 1 (default): Your Homepage. False : The zoom level should be applied on the current tab only. close : Prevents the close button from being disabled. directories : Prevents the bookmarks toolbar from being hidden. location : Prevents the books essay Pomfret School, address bar from being hidden. minimizable : Prevents popup window minimization from being disabled. personalbar : Prevents the bookmarks toolbar from being hidden.
resizable : Prevents popup window resizing from being disabled. scrollbars : Prevents the scrollbars on bussines review School of Milan, a popup from how to The Windsor School, being disabled. status : Prevents the harvard review International School of Milan, status bar from being hidden. toolbar : Prevents the navigation toolbar from being hidden. False : Move to the new tab immediately. False (default) - Do not export HTML at shutdown. Will be needed for write for an essay The Windsor School 3.1 and 3.2 so that Ctrl+Tab, Ctrl+Shift+Tab work browser.ctrlTab.previews removes tab preview. # Set browser.ctrlTab.mostRecentlyUsed to false (create name) # Set browser.ctrlTab.recentlyUsedLimit to 0. also check these into table.
Updates are with Notepad like all my other pages, and use of CopyURL+ extension with a 3 column pattern may be used for some additions. Modifying configuration entries should be intuitive, but more help is available at http://kb.mozillazine.org/About:config. I've landed bug 465076 today. Harvard Of Milan. The UI is critical thinking problem Durham University now disabled on trunk. This is controlled by the browser.allTabs.previews and browser.ctrlTab.previews preferences.
I'd like to encourage nightly testers and whoever's interested to flip both prefs and report bugs, so that we can make further progress there. Review. I've filed bug 505404 for tracking these bugs. Essay Writing Pomfret. (2009-07-21, by Dao) Finding Preference Related Information (and sorting preferences) (#findprefinfo) You can type about:support into the location bar to see ONLY changed settings. Change preferences are in review, the Modified Preferences section, which is in alphabetical order. For other sections you may have to sort table columns with a bookmarklet or with an extension.
An additional advantage to using the extension is that you can sort first on a minor sort and then on your major sort, the bookmarklet only gives you one column of sorting. Finding more information about article School, your preferences: In your about:config list, right-click on the preference name (or row) and choose Prefsearch -- if you have installed https://addons.mozilla.org/firefox/addon/prefsearch/ In your about:support list select the bussines review International, preference name, then use built-in search by right-clicking on selection and choosing Search Google for . About Writing International Of Hotel. (uses your default search engine) Most of the harvard bussines review School of Milan, common user assigned preferences are in. if they relate to solving, tabs, I probably have them here on this page, with additional information. http://www.mvps.org/dmcritchie/firefox/tabs_config.htm (this page)
Summary of International my Tab related changes (#summary) You can see my complete InfoLister listing of Pomfret extensions I have currently installed (some are disabled), and you can find descriptions and usage notes for those and extensions I may have used in the extensions table within Firefox Customization (Notes) where you will find my notes on the following extensions. The extensions below total 198KB compared to harvard School of Milan, the troublesome Tabs Mix Plus extension (417KB). Multiple Tab Handler, (48KB), working with selections of tabs) New Tab Button (32KB) restores the pre Firefox 3.1 new tab button to toolbar. Perma Tabs Mod (48KB), (prevents tab(s) from being closed/replaced via a link) Stay-Open Menu (16kb), keeps menu open after Ctrl+click or Ctrl+Shift+click either of which start a new tab.
Tab Clicking Options (29KB), replaces close tab with double click (2KB), but this one works with Multiple Tab Handler. Tab Counter (23KB), Counts the number of nursing writing College open tabs per window and displays the count in bussines International of Milan, the toolbar. Nursing Seneca. [Options]. Tab Search , (2KB) I don't use it, but it would be better than stuff being proposed by FF developers.
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Education in Microscopy and Digital Imaging. In transmitted light microscopy, the specimen quality does not always lend itself to easy observation and image recording with excellent contrast in simple brightfield imaging mode. Investigations dealing with inherently low-contrast specimens, such as unstained bacteria, thin tissue slices, and adherent live cells, rely on specialized contrast-enhancing techniques to assist with imaging these virtually transparent samples. In the course of examining unstained specimens, poor light absorption by the specimen results in harvard bussines review School, extremely small variations in the intensity distribution difference between the specimen and the background. When the background is article writing Les Roches School bright, the human eye requires local intensity fluctuations of at least 10 to 20 percent to be able to recognize specimen details.
Unfortunately, this level of modulation is seldom seen with transparent specimens, which are usually rendered almost invisible against a background of similar intensity. The term transmitted light , when used in harvard review School of Milan, optical microscopy, refers to any imaging modality where light is passed from the illumination source on the opposite side of the Seneca College specimen to the objective (thus, illumination is transmitted through the specimen). The contrast-enhancing techniques described in this section represent a variety of methods in sample preparation as well as optical tricks that generate intensity changes which are useful for harvard International of Milan, observation and imaging. Methods that enhance contrast include differential interference contrast ( DIC ), polarized light, phase contrast, Hoffman modulation contrast, and darkfield microscopy (examples are illustrated in Figure 1). Several of these techniques are limited by light originating in regions removed from the focal plane when imaging thicker plant and animal tissues, while polarized light requires birefringence (usually not present to a significant degree in animal cells) to generate contrast. Illustrated in Figure 1 are a variety of popular contrast-enhancing techniques that are commonly employed in transmitted light microscopy. Article International Of Hotel! The thin tissue section in Figure 1(a) reveals a human basal cell carcinoma stained with eosin and hematoxylin to generate color contrast in review International of Milan, brightfield imaging mode.
Figure 1(b) shows living HeLa cells in a plastic tissue culture vessel imaged with phase contrast. A fixed culture of Indian Muntjac cells mounted in an aqueous medium are presented in differential interference contrast image in Figure 1(c). A fresh tissue section of mouse heart muscle bathed in trip writing Limkokwing, aqueous saline solution is displayed in the Figure 1(d) panel, where contrast is generated using Hoffman modulation (or ZEISS VAREL) contrast, an oblique illumination technique. The brilliant bright-on-dark contrast observed with darkfield illumination is review International School shown in Figure 1(e) using an article International of Hotel, Obelia hydroid specimen. Finally, rabbit skeletal muscle fibers (Figure 1(f)) are among the biological specimens that are birefringent and demonstrate contrast in polarized light.
One of the primary and favorite techniques used in all forms of bussines School, optical microscopy for the past three centuries, brightfield illumination relies upon changes in light absorption, refractive index, or color for generating contrast. As light passes through the specimen, regions that alter the direction, speed, and/or spectrum of the wavefronts generate optical disparities (contrast) when the rays are gathered and focused by the objective. Resolution in article writing International School of Hotel, a brightfield system depends on both the objective and condenser numerical apertures, and an immersion medium is required on both sides of the specimen (for numerical aperture combinations exceeding a value of 2.3). Digital cameras provide the wide dynamic range and spatial resolution required to capture the information present in a brightfield image. In addition, background subtraction algorithms, using averaged frames taken with no specimen in the optical path, increases contrast dramatically. Simple brightfield imaging, with the harvard bussines International of Milan microscope properly adjusted for Kohler illumination, provides a limited degree of how to a conclusion The Windsor School, information about the cell outline, nuclear position, and the location of larger vesicles in unstained specimens. Contrast in brightfield imaging depends on differences in light absorption, refractive index or color.
Optical disparities (contrast) are developed as light passes through the specimen altering the harvard bussines International of Milan direction, speed or spectral characteristics of the imaging wavefront. Journals Anglia University (Navitas)! The technique is review School of Milan more useful with specimens stained with visible light absorbing dyes (such as eosin and hematoxylin; see Figure 1(a)). However, the general lack of contrast in brightfield mode when examining unstained specimens renders this technique relatively useless for serious investigations of living cell structure. First described by the Dutchman Frits Zernike in 1934, phase contrast earned its discoverer the Nobel Prize for physics in reviewed journals Ruskin, 1953 while revolutionizing basic biomedical research on harvard review of Milan, living cells. The technique is ideal for thin unstained specimens (such as culture cells on glass), which are approximately 5 to 10 micrometers thick above the about writing International nucleus, but less than a micrometer thick at the periphery. Such specimens barely exhibit any light absorption in the visible portion of the harvard bussines International spectrum and the human eye cannot detect them in brightfield and books essay writing, darkfield illumination. Harvard Bussines International School! Phase contrast (as illustrated in nursing writing Seneca, Figure 1(b)) employs an optical mechanism to translate minute variations in phase into corresponding changes in amplitude, which can be visualized as differences in image contrast. The microscope must be equipped with a specialized condenser containing an annulus or a series of annuli matched to a set of harvard bussines review, objectives containing phase rings (designed Ph ) in the rear focal plane (phase contrast objectives can also be used with fluorescence, but with a slight reduction in transmission). Phase contrast is an excellent method to increase contrast when viewing or imaging living cells in culture, but typically results in halos surrounding the outlines of edge features. Write A Conclusion For An Essay The Windsor School! These halos are optical artifacts that often reduce the visibility of boundary details.
The technique is not useful for thick specimens (such as plant and animal tissue sections) because shifts in phase occur in regions removed from the focal plane that distort image detail. Furthermore, floating debris and other out-of-focus phase objects interfere with imaging adherent cells on coverslips. As presented in review of Milan, Figure 2, very small differences exist between the refractive indices of the about article International Management cells and their surrounding aqueous solutions and within the cells between the cytoplasm (Figure 2(b)) and the cell nucleus (Figure 2(c)). No significant refractive index difference occurs in the coverslip and surrounding medium (Figure 2(a)). Phase contrast makes these tiny differences visible by the use of optical manipulation as, for example, it translates them into differences in harvard bussines School of Milan, intensity that can be visually observed and recorded. The optical effect employed in this case consists of reviewed Anglia University, a shift of phase relationships between light wavefronts traveling through different portions of the harvard review School specimen. During their journey through cell nuclei, cytoplasm, or water, the light waves are shifted (retarded) by small degrees, since these media have slightly different refractive indices (the higher the refractive index of a medium, the smaller the trip essay University speed or velocity of light in the medium). As a result, a light wave that has passed through a cell nucleus lags behind the light waves that only had to pass through water (compare Figure 2(a) and Figure 2(c)). The amount of lag is called a phase shift. Before their entry into bussines review of Milan the specimen, the waves are still in phase (wavefronts beneath the coverslip), but this is no longer the case when they have passed through the various materials having different refractive indices. The amount of the phase shift depends on what media (refractive index) the waves have passed through on their paths, and how long the paths were through these media.
The human eye cannot see these phase shifts in the microscope image, it is only able to distinguish between different intensities and essay writing Seneca College, colors. Therefore, the phase contrast technique uses optical tricks to translate phase shifts into bussines review School grey values. In phase contrast microscope configuration, the condenser aperture diaphragm is replaced by a phase stop (the size of which depends upon objective and condenser numerical aperture) that illuminates the specimen via the condenser optical components in a hollow cone of light fashion, as illustrated in Figure 3(a). These wavefronts enter the critical thinking problem University objective and an image of the phase stop is created in the rear focal plane (the objective pupil). Positioned within the objective rear focal plane is a phase ring or plate that not only attenuates the bright, direct light originating from the phase stop in harvard bussines review International School of Milan, the condenser, but also adds a constant phase shift to trip writing Limkokwing this light. If the harvard International of Milan specimen contains sub-structures that have mixed refractive indices, these entities guide the light from the direct waves into new paths (red dotted line in Figure 3(a)). Wavefronts diffracted by Pomfret School the specimen (in effect, those containing structural information) will not pass through the harvard review International of Milan phase ring in the objective, meaning that they will not be attenuated or retarded.
All of the wavefronts are ultimately recombined to books essay writing Pomfret School form the intermediate image by the tube lens. The wavefronts that have all been retarded to varying degrees by details in the specimen are superimposed in the intermediate image over the shifted and attenuated wavefronts where they amplify or attenuate each other (depending on the phase), forming the bussines International School final phase contrast image observed in the eyepieces. Writing! These interference processes in the intermediate image create bright and harvard review, dark areas of the various structures having refractive index (and/or thickness) variations in the specimen. Optimum contrast is created by selecting the correct retardation and reviewed Anglia University, attenuation values, which is a function of the optical properties of the harvard review International School phase ring in the objective aperture. A major artifact of phase contrast imaging is the essay writing bright halos of bussines review International School of Milan, light that appear on the borders surrounding the International Management specimen. Halos occur in phase contrast microscopy because the circular phase-retarding (and neutral density) ring located in the objective phase plate also transmits a small degree of diffracted light from the specimen (it is not restricted to passing surround waves alone).
The problem is compounded by the fact that the width of the non-diffracted light (zeroth-order) surround wavefront projected onto the phase plate by the condenser annulus is smaller than the International actual width of the a conclusion for an School phase plate ring. Thick specimens, often exhibiting highly overlapping structures, produce severe halo artifacts. Therefore, phase contrast is a method that is only recommended for very thin specimens where several structures are not physically lying on International of Milan, top of each other. Trip! In a thick specimen, details may be blended into an image that, in the final analysis, is no longer legible. Phase contrast requires special objectives that are equipped with a phase ring near the pupil or rear aperture. Review International! They are easy to critical thinking problem solving Durham recognize by the green inscription that denotes the size of the corresponding condenser phase stop: Ph1 , Ph2 , or Ph3 . If you hold such an objective against the light and bussines review International School, look into the pupil from the threaded end, you will be able to see the grey/transparent phase ring. The condenser requires one, two, or three phase stops, depending on the phase contrast objectives that are attached to the microscope nosepiece. The required ring diameter increases with the numerical aperture (high apertures require the maximum diameter ( Ph3 ), for example 0.9 in air or 1.3 with oil immersion). Three sizes are available and are sufficient for all objectives (Figure 3(b)). If you use phase contrast with only one ring size, an easily attachable and trip essay writing Limkokwing University, removable plug-in stop for the condenser will suffice.
A turret disk with several mounts is more convenient, since it contains all three phase stops and enables very fast changeover during imaging. Additional openings are available for the aperture iris necessary in brightfield illumination and for the darkfield diaphragm. The phase stops must be centered after they have been installed in the condenser so that the image of the phase stop in bussines review School of Milan, the objective pupil corresponds exactly with the position of the phase ring in the beam path (see Figure 4(c)). Centering is performed using two small wrenches (or screwdrivers, depending upon books essay Pomfret School, the microscope model) on the turret disk of the harvard review of Milan condenser. If you want to be particularly precise, use a centering telescope to observe the objective rear aperture for making these adjustments, as illustrated in nursing essay College, Figure 4. This small accessory looks like an eyepiece and is inserted into the observation tube in place of an eyepiece. When the telescope is focused on the pupil (rear aperture) of the objective, the position of the phase stops can be clearly observed. Again, look into the objective pupil and bring the bright image of the condenser phase stop into coincidence with the phase ring of the harvard School of Milan objective. This is clearly shown in Figure 4. In Figures 4(a) and essay writing University, 4(b), the harvard bussines of Milan phase stop is not aligned with the objective phase plate, while the stop and phase plate are in perfect congruence in Figure 4(c).
The image of a specimen in phase contrast can be influenced by appropriately selecting the retardation of the how to write a conclusion The Windsor direct (non-diffracted) beam through careful selection of the phase ring in the objective. Depending on the retardation value selected, objects with a higher refractive index than their surroundings appear either brighter or darker than their surroundings. This is also called either positive or negative phase contrast. In modern microscopes, positive phase contrast is standard, where the darkness of object features increases with their refractive index. The effect simulates absorption to the observer's eye in areas where a higher refractive index produces high contrast features.
This impression is considered the optimum, particularly with cells and tissue in aqueous media because cell nuclei and organelles, for example, appear darker than the cytoplasm. For some applications, such as examining sperm cells, negative phase contrast may produce more specimen detail than the traditional positive phase contrast. back to top ^ Differential Interference Contrast. Differential interference contrast microscopy ( DIC ; Figure 1(c)) requires plane-polarized light and additional light-shearing (Nomarski) prisms to exaggerate minute differences in of Milan, specimen thickness gradients and refractive index. Lipid bilayers, for example, produce excellent contrast in DIC because of the nursing essay Seneca difference in harvard bussines of Milan, refractive index between aqueous and lipid phases of the cell.
In addition, cell boundaries in relatively flat adherent mammalian and nursing writing College, plant cells, including the plasma membrane, nucleus, vacuoles, mitochondria, and stress fibers, which usually generate significant gradients, are readily imaged with DIC. In plant tissues, the birefringent cell wall reduces contrast in bussines of Milan, DIC to a limited degree, but a properly aligned system should permit visualization of nuclear and vacuolar membranes, some mitochondria, chloroplasts, and condensed chromosomes in a conclusion for an The Windsor School, epidermal cells. Differential interference contrast is an important technique for harvard review International of Milan, imaging thick plant and animal tissues because, in addition to the increased contrast, DIC exhibits decreased depth of field at thinking problem Durham University wide apertures, creating a thin optical section of the thick specimen. This effect is also advantageous for imaging adherent cells to minimize blur arising from floating debris in the culture medium. The differential interference contrast optical system is based on the polarized light contrast technique as far as many of the components utilized are concerned. Harvard Bussines Review International School! DIC for a modern transmitted light microscope is different than that in reflected light because two birefringent prisms are used (see Figure 6), and the specimen's optical path difference is determined by how to write a conclusion the product of the refractive index difference (between the specimen and its surrounding medium) and harvard International, the thickness (geometrical distance) traversed by a light beam between two points on books essay writing School, the optical path (Figure 5). Images produced in bussines review International of Milan, differential interference contrast microscopy are characterized by books writing Pomfret a distinctive shadow-cast appearance, as if they were illuminated from a highly oblique light source originating from a single azimuth. Unfortunately, this effect, which often will render a specimen in a pseudo three-dimensional relief (Figure 6(d)), is frequently assumed by uninformed microscopists to be an indicator of actual topographical structure. Figure 6 illustrates the differential interference contrast beam path that is similar to that of harvard School, polarized transmitted light.
In DIC (as compared to polarized light), the two birefringent prisms (Figure 6(b)) are inserted into the optical train, one in the condenser and about International School, the second near the objective pupil. The condenser prism performs a vectorial decomposition of the previously linearly polarized light (Figure 6(c)) into two vibration directions that are perpendicularly polarized to harvard review International each other, and laterally shifts these partial beams in such a way that a small lateral displacement of the wavefronts occurs where regions of thickness or refractive index vary. If the write a conclusion two partial beams now pass through exactly the same structures, no further path difference will occur in the specimen (Figure 5(a) and Figure 5(c)). However, if the two partial beams see slightly different conditions, each of them will experience a slightly difference pathlength that accompanies it on the remaining trip to the intermediate image plane (Figure 5(b)). As discussed, the split DIC light beams enter and pass through the specimen where their wave paths are altered in harvard bussines review International School of Milan, accordance with the specimen's varying thickness, slopes, and refractive indices.
These variations cause alterations in the wave path of both beams passing through areas of any specimen details lying close together. When the parallel beams enter the objective, they are focused above the rear focal plane where they enter a second DIC prism that combines the two beams at a defined distance outside of the prism itself. Nursing College! This removes the shear (distance between the waves) and the original path difference between the beam pairs. As a result of having traversed the specimen, the paths of the parallel beams are not of the same length (optical path difference) for differing areas of the specimen. In order for harvard bussines School, the beams to interfere, the vibrations of the beams of different path length must be brought into the same plane and axis. Limkokwing University! This is accomplished by placing a second polarizer (analyzer) above the upper DIC beam-combining prism. The light then proceeds toward the harvard of Milan eyepiece where it can be observed as differences in books essay writing School, intensity and color. The design results in one side of a specimen detail appearing bright (or possibly in color) while the other side appears darker (or another color). This shadow effect bestows the pseudo three-dimensional appearance to the specimen that was described above.
There are numerous advantages in DIC microscopy as compared to phase contrast microscopy. Bussines Review School! With DIC, it is possible to make fuller use of the numerical aperture of the system and to College provide optical staining (color). DIC also allows the microscope to achieve excellent resolution. Use of full objective aperture enables the microscopist to focus on a thin plane section of School, a thick specimen without confusing images from critical thinking problem Durham University, above or below the plane. Annoying halos, often encountered in phase contrast, are absent in DIC images, and suitable achromat and fluorite objectives can be used for this work. It is bussines review International School of Milan important to keep in mind, however, since DIC is based on polarized light principles, highly birefringent specimens or those embedded in birefringent materials should not be observed under DIC. back to top ^ Hoffman Modulation and VAREL Contrast. Often metaphorically referred to as poor man's DIC, Hoffman modulation contrast ( HMC ) is an oblique illumination technique that enhances contrast in Anglia Ruskin (Navitas), living cells and tissues by detection of review of Milan, optical phase gradients (see Figure 1(d)). The basic microscope configuration includes an optical amplitude spatial filter, termed a modulator, which is inserted into the rear focal plane of the objective. Light intensity passing through the modulator varies above and books, below an average value, which by definition, is then said to harvard bussines review International School be modulated. Coupled to the objective modulator is an off-axis slit aperture that is placed in the condenser front focal plane to direct oblique illumination towards the how to a conclusion School specimen.
Unlike the phase plate in harvard bussines International School of Milan, phase contrast microscopy, the Hoffman modulator is designed not to alter the phase of light passing through; rather it influences the principal zeroth order maxima to produce contrast. Hoffman modulation contrast is not hampered by the use of birefringent materials (such as plastic Petri dishes) in the optical pathway, so the technique is more useful for examining specimens in containers constructed with polymeric materials. On the downside, HMC produces a number of write The Windsor, optical artifacts that render the harvard bussines School technique somewhat less useful than phase contrast or DIC for live-cell imaging on trip essay, glass coverslips. A newly developed contrasting technique, in which phase contrast is combined with inclined unilateral illumination (similar to HMC), has been developed for the examination of living cells in culture vessels. An additional stop shaped like a ring sector is used on the illumination side, permitting unilateral inclined illumination. Three illumination modes, unilateral darkfield, VAREL (variable relief) contrast, and inclined brightfield (similar to oblique illumination or HMC) are set by harvard bussines International School shifting the stop in the radial direction from the how to for an essay The Windsor outside to the inside (see Figure 7) and a segment of a matching annulus is harvard review International moved into position. This slit directs the source illumination to pass through a second ring of high absorption on the objective aperture's periphery, which suppresses its intensity by an amount dependent upon the density of the outer ring. Pomfret School! The diffracted orders of light pass through the objective without being suppressed by the VAREL ring. Bussines International School Of Milan! You can also manipulate the position of the slit if you want to vary the how to write a conclusion for an essay The Windsor School extent the source illumination is bussines review International School of Milan suppressed.
Orientation is easy to achieve and about International School of Hotel, maintain because of the concentric nature of the slit. Furthermore, because of the VAREL ring's location in the objective, VAREL and phase contrast rings can be combined in bussines review, the same objective. This makes for a very low-price method of imaging cells in culture vessels. The problems of imaging in both traditional and routine tissue culture applications can be resolved with this method, it is about Les Roches School a successful option for the examination of living objects (micromanipulation), and a range of structures with varying optical thickness are easily imaged with VAREL. Even culture vessels with a curved bottom allow a useful image to be produced. Phase contrast alone sometimes fails in such cases because a curved chamber base acts like a lens and bussines review International School, impairs the superimposition of phase rings. A slider contains two of the essay writing Pomfret School mentioned sectors to bussines School allow illumination to be performed from the trip essay writing University left or right, as required. This makes it possible to contrast cells even near the edges of the harvard bussines International School of Milan holes in microtiter plates. The methodology surrounding darkfield microscopy, although widely used for imaging transparent specimens throughout the 19th and 20th Centuries, is limited in use to Les Roches International physically isolated cells and harvard of Milan, organisms (as presented in essay writing, Figure 1(e)). In this technique, the condenser directs a cone of light onto the specimen at high azimuths so that first-order wavefronts do not directly enter the objective front lens element.
Light passing through the specimen is diffracted, reflected, and/or refracted by optical discontinuities (such as the bussines International School cell membrane, nucleus, and internal organelles) enabling these faint rays to enter the objective. Critical Thinking Problem Solving Durham University! The specimen can then be visualized as a bright object on an otherwise black background. Unfortunately, light scattered by objects removed from the focal plane also contribute to the image, thus reducing contrast and obscuring specimen detail. This artifact is compounded by the fact that dust and debris in the imaging chamber also contribute significantly to the resulting image. Furthermore, thin adherent cells often suffer from very faint signal, whereas thick plant and animal tissues redirect too much light into the objective path, reducing the effectiveness of the technique. Recently, a renewed interest in transmitted darkfield microscopy has arisen due to its advantages when used in combination with fluorescence microscopy. Darkfield microscopy is bussines review International a specialized illumination technique that capitalizes on oblique illumination, as described above, to enhance contrast in specimens that are not imaged well under normal brightfield illumination conditions.
An artificial dark background is created in the microscope using an annular stop in the condenser (see Figure 8). Although the thinking condenser optics then illuminate the sample, they do so with a hollow inverted cone of light that passes through the specimen at extremely oblique angles at all azimuths so that only the light interacting with specimen features is able to enter the microscope objective to form a bright image of the specimen superimposed onto a dark background. To create the high angles, it is necessary for harvard bussines review International School, the objective aperture to be smaller than the inner aperture of the illuminating light cone (see Figure 8(a)). Trip Essay University! However, objectives with an integrated variable iris diaphragm are also available to shutter out the indirect light even if it falls into the aperture cone of the objective (as illustrated in Figure 8(b)). This permits the use of very high apertures for darkfield illumination. Darkfield microscopy is an excellent tool for biological and medical investigations. It can be effectively used at high magnifications to bussines International image living bacteria, or at low magnifications to books Pomfret view and image cells, tissues, and whole mounts. Polarized light microscopy is a contrast-enhancing technique that dramatically improves the quality of an harvard bussines review of Milan, image acquired with birefringent materials when compared to other techniques such as brightfield and darkfield illumination, phase contrast, differential interference contrast, fluorescence, and Hoffman modulation contrast.
Polarized light microscopes possess a high degree of sensitivity and nursing essay writing Seneca, can be used for both qualitative and quantitative studies targeted at harvard bussines review School of Milan a wide range of anisotropic specimens. Qualitative polarizing microscopy is quite popular in practice, however, the quantitative aspects of books Pomfret School, polarized light microscopy, which are principally applied in crystallography, represent a much more difficult subject that is primarily used by harvard bussines International of Milan mineralogists, geologists, and chemists. The steady advances achieved over the past few years in highly sensitive polarized light microscopy have allowed biologists to Anglia Ruskin examine the birefringent character of several anisotropic sub-cellular assemblies. Polarized light microscopy (Figure 1(f)) is conducted by viewing the International School specimen between crossed polarizing elements inserted into solving the optical train before the condenser and harvard bussines International School, after the objective. Journals! Assemblies within the cell having birefringent properties, such as the plant cell wall, starch granules, and the mitotic spindle, as well as muscle tissue, rotate the plane of light polarization, appearing bright on a dark background. The rabbit muscle tissue illustrated in Figure 1(f) is an example of polarized light microscopy applied to living tissue observation. Note that this technique is harvard bussines review International of Milan limited by the occurrence of nursing essay writing Seneca, birefringence in living cells and tissues, and has yet to be fully explored. As mentioned above, differential interference contrast operates by placing a matched pair of opposing Nomarski prisms between crossed polarizers, so that any microscope equipped for harvard bussines International of Milan, DIC observation can also be employed to examine specimens in plane-polarized light simply by critical solving Durham University removing the prisms from the harvard bussines review School optical pathway. There are two polarizing elements in a polarizing microscope (see Figure 9).
The first polarizer is placed beneath the specimen stage with its vibration azimuth fixed in the East-West direction. Note most of these elements in commercial microscopes can be rotated through 360 degrees. Another polarized (the analyzer), which is usually aligned with a vibration direction oriented North-South (but again rotatable on some microscopes), is placed above the University (Navitas) objective and can be moved into and out bussines review of Milan, of the light path as needed. When both the about International School of Hotel Management polarizer and analyzer are inserted into the optical path, their vibration azimuths are positioned at International School of Milan right angles to essay writing College each other. In this configuration, the harvard bussines review International School polarizer and analyzer are crossed, with no light passing through the optical system and a dark background present in the eyepieces (Figure 9(a)). A Conclusion Essay The Windsor School! Linearly polarized light waves are generated by polarizers that filter out a privileged plane from the statistical confusion of vibrational directions prevailing in natural light. The two orthogonal components of harvard review International of Milan, light (ordinary and extraordinary waves) travel at College different speeds through the harvard review International specimen and, as a result, observe different refractive indices, a phenomenon known as birefringence (derived from the terms double or bi refraction ). A quantitative measurement of birefringence equals the critical thinking Durham University numerical difference between the bussines review International School of Milan wavefront refractive indices.
The faster wavefront emerges first from the specimen to generate an optical path difference with the slower wavefront. The analyzer recombines components of the two wavefronts traveling in the same direction and vibrating in the same plane. Nursing Writing! This polarizing element ensures that the harvard bussines review School two wavefronts have the critical thinking solving Durham same amplitude at the time of recombination for maximum contrast. The appropriate arrangement for polarized light imaging is harvard review International of Milan relatively easy to implement on virtually any microscope. The polarizer beneath the essay University condenser (near the aperture diaphragm) ensures that the specimen is bussines review of Milan illuminated with linearly polarized wavefronts that pass through the condenser (refer to Figure 9(a)). The analyzer (a second polarizer), which is oriented with the azimuth arranged at trip essay writing University an angle of 90 degrees to that of the polarizer, is located behind the objective. The tube lens forms the harvard bussines International intermediate image, which is projected through the eyepieces or onto a camera imaging plane.
If no specimen is placed on the microscope stage, the scene observed through the eyepieces will remain completely dark. When illuminated, many specimens turn the vibration direction of the polarized light out of the plane produced by the polarizer. Such specimens consist mainly of birefringent materials, in which the refractive index depends on essay writing, the vibration direction of the incident light. This is mainly the International case with crystals, such as starch or minerals (Figure 9(c)), but also occurs with fibers (Figure 9(d)) and polymers. If such materials are viewed under the polarization microscope between the crossed polarizer and the analyzer, bright areas can be seen in the image because light is partially transmitted by the analyzer. The polarized light microscope optical train can also include an auxiliary element known as a lambda or retardation plate (Figure 9(a) and 9(b)) that is used in critical problem Durham University, quantitative analysis. In polarized light, this lambda plate converts contrast into colors. As in harvard bussines International, phase contrast, optical path differences give rise to colors, although this time with polarized light and birefringent material in the specimen. The path differences generated leads to an extinction of certain wavelengths in article Les Roches International of Hotel Management, the light through interference (only certain colors remain from the white light and create beautiful, colored pictures). Polarizing microscopy offers an immense amount of information about the composition and review of Milan, three-dimensional structure of a range of samples.
Practically unlimited in its scope, the technique can reveal information about thermal history and books writing Pomfret School, the strains to which a specimen was subjected during formation. Bussines International! Valuable in manufacturing and essay, research, polarizing microscopy is relatively inexpensive and an accessible research and quality control tool that can provide information unavailable with any other technique. Rudi Rottenfusser - Zeiss Microscopy Consultant, 46 Landfall, Falmouth, Massachusetts, 02540. Erin E. Wilson and review International School, Michael W. Davidson - National High Magnetic Field Laboratory, 1800 East Paul Dirac Dr., The Florida State University, Tallahassee, Florida, 32310.