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What is a PID controller?

A PID (Proportional Integral Derivative) controller is a common instrument used in industrial control applications. A PID controller can be used for regulation of speed, temperature, flow, pressure and other process variables. Field mounted PID controllers can be placed close to the sensor or the control regulation device and be monitored centrally using a SCADA system.

Example: Temperature Control using a Digital PID controller

A typical PID temperature controller application could be to continuously vary a regulator which can alter a process temperature. This may be a pulsed switching device for electrical heaters or by opening and closing a gas valve. A heat only PID temperature controller uses a reverse output action, i.e. more power is applied when the temperature is below the setpoint and less power when above. PID control for injection and extrusion applications often employ additional cooling control outputs and usually require multiple controllers.

A PID controller (sometimes called a three term controller) reads the sensor signal, normally from a thermocouple or RTD, and converts the measurement to engineering units e.g. Degrees C. It then subtracts the measurement from a desired setpoint to determine an error.

The error is acted upon by the three (P, I & D) terms simultaneously:

PID Controller Theory

The following section examines PID controller theory and provides further explanation of the question `how do PID controllers work’.

Proportional (Gain)

The error is multiplied by a negative (for reverse action) proportional constant P, and added to the current output. P represents the band over which a controller’s output is proportional to the error of the system. E.g. for a heater, a controller with a proportional band of 10 deg C and a setpoint of 100 deg C would have an output of 100% up to 90 deg C, 50% at 95 Deg C and 10% at 99 deg C. If the temperature overshoots the setpoint value, the heating power would be cut back further. Proportional only control can provide a stable process temperature but there will always be an error between the required setpoint and the actual process temperature.

Integral (Reset)

The error is integrated (averaged) over a period of time, and then multiplied by a constant I, and added to the current control output. I represents the steady state error of the system and will remove setpoint / measured value errors. For many applications Proportional + Integral control will be satisfactory with good stability and at the desired setpoint.

Derivative (Rate)

The rate of change of the error is calculated with respect to time, multiplied by another constant D, and added to the output. The derivative term is used to determine a controller’s response to a change or disturbance of the process temperature (e.g. opening an oven door). The larger the derivative term, the more rapidly the controller will respond to changes in the process value.

Tuning of PID Controller Terms

The P, I and D terms need to be “tuned” to suit the dynamics of the process being controlled. Any of the terms described above can cause the process to be unstable, or very slow to control, if not correctly set. These days temperature control using digital PID controllers have automatic auto-tune functions. During the auto-tune period the PID controller controls the power to the process and measures the rate of change, overshoot and response time of the plant. This is often based on the Zeigler-Nichols method of calculating controller term values. Once the auto-tune period is completed the P, I & D values are stored and used by the PID controller.

Now that there are a large range of subjects available, an online degree has something that is suitable for everybody.

To discover which online degree is right for you, first you should be definite concerning your career objectives. For example, if you want to start your own small business, then a degree in marketing will be your ideal bet. Someone else may use an online degree in order to help them change careers.

Usually all you need to be able to enroll is a high school diploma or G.E.D and a desire to learn. Depending on your previous college grades and work record, you may be able to receive your degree in a relatively short time.

Before selecting a university which you are interested in, be sure that they are fully accredited and the staff has an extensive understanding of the subject which you are interested in.

Once you have decided to enroll, getting started is easy, many colleges provide year round enrollment, this means you can start on your course immediately, you have signed up. The course work will be available for download over the internet as soon as you want to, so that you can start as soon as you wish.

What are the advantages you will get by doing an Online Degree?

Normally an online degree course takes four years to complete, the biggest benefit of an online degree is the potential to finish the degree in less time. It is not unusual for students to complete their degree in less than three years.

Any previous college credits can be taken into consideration also pertinent work history will be take into consideration, this could reduce the time even more you might even complete your degree in as little as six months.

The next important benefit of an online degree is that the course work is extremely flexible, the work can be done at any time throughout the day and you never have to leave your house. Any course work is carried out via the Internet both by lessons you download or via virtual class work.

These courses do require hard work, on average an online degree program will require a minimum of twenty hours of class work per week, but because the course is completed online, you can work at your own pace, depending on your schedule, always provided the course is completed within the allowed time.

Generally the standard time frame allowed for the class work of an online degree is one class every five weeks. This schedule allows you to concentrate completely on one class or module at a time letting you learn all of the information presented in that lesson. This is better than traditional four year colleges because with an online program you can devote your time to each session without being sidetracked by other classes and information.

Tuition payment is also easier with an online course. Online degree programs usually qualify for the same tuition aide that on-site courses do, so you are able to apply for student loans, payment plans and employer payment programs. Furthermore, some online colleges will let you to pay as you learn, this helps with initial college costs.

Studying on line for a degree is a great way for those of us that are working full time to further their careers. When studying online, you can keep your job and still obtain a degree in a reasonable time, online degrees are also the perfect choice for anybody that must work full time to pay for the cost of their education.

If you are thinking of going for a degree, then an online degree program is with out a doubt worth checking out.

By deciding on an accredited online degree course as against a regular degree program, you are still getting a degree of especially high standard, that you can work for at home in a flexible manner.

Cambodia has very long and protracted history and culture. We can see that merriments related to culture are almost uncountable. The Khmer New Year is one of the most important cultural festivities in Cambodia, so it would be of great values to take a little hint into what is Khmer New Year.

Cambodian (Khmer) New Year is celebrated every year in the middle of the month of April. Khmer New Year does not single-mindedly aim at merry-making or bringing entertainment, in fact, it contains much more useful connotations to edify Cambodian people’s mentalities. One of the aims is to refresh the undesirable livelihood in the past, and to enter into a better livelihood in the closely upcoming year. Cambodian people can wish for better lives in the Khmer New Year, if their lives in the past year was good, they wish for the better, and if their past lives were bad, they wish for the better as well. As we can see, the people buy new clothes, clean the houses and Buddhist pagodas and other religious shrines. Moreover, the elderly clergymen advise the disputed parties to resolve and to forget the revenge and reunion as one family during this New Year.

Khmer traditional games that are played during the New Year have their unique meanings, besides the entertainments. All of the game edifies the Cambodian youths, teenagers to consolidate, use intellectual power to overcome the obstacles, empower justice, values of forgiveness, power of love, and other desirable ideologies.

Besides the Khmer traditional games, people always visit their birth-land to prey for the dead ancestors, visit their parents or grandparents (a number of people in Phnom Penh are from the provinces, only a small number of them were born in Phnom Penh and have parents and grandparents in Phnom Penh). It is a nice reunion between relatives; close and distant alike, in the province. Of course, it is fund; having meal among a huge number of people, playing Khmer traditional games together, go sightseeing around the communities surrounded by rice paddies and nature. But sadly, at the end of the merriments, they have to separate to go back to their work.

It is the law of the religion that people have to the pagodas, at least once during the Khmer New Year, otherwise, they will be maliciously wished from their dead ancestors, who are their grandparents, parents, or other close relatives. Food, desserts, and other everyday-use items are brought to the pagoda, and as the people donate those stuffs to the Buddhist monks, the people need to remind themselves the names of their dead ancestors. The things the people donate through the monks, are thought to reach to the hands of the dead ancestors in the hell, the more they donate, the better the dead ancestors will wish for them, and so they are called “the grateful”. We can also see people of all ages like to reunite to play the traditional games in the pagoda, because the pagoda has huge empty area, suitable for the play, and because the pagoda is always crowed, so it makes the play even more exciting.

The Khmer traditional games are: Bose Angkogn, Chaol Choung, traditional Khmer dancing, Leak Kanseng, the ambitious king, Leang Ouk…etc. But I can’t explain these games into English words, because they are complicated to translated into English words, and some words aren’t existed in the English vocabulary. But a small number of people are negatively turning the meanings of the traditional games, but playing especially cards, Ha Poung, etc to gain profits.

The Khmer New Year is always celebrated for three days; 15th, 16th, 17th every the month of April. But recently I notice a brand new game which is “splashing water on each other”. I don’t know whether splashing water on each other is the Khmer traditional game or not.

Copyright 2005 Jason Bibb

Aerodynamics is one of the leading factors in vehicle performance. Car racing has focused on this aspect ever since the 60s, when the first inverted wings were installed on formula cars. In time, the development of aerodynamic devices grew stronger, often borrowing ideas and solutions form the flight industry.

By improving aerodynamics, engineers saw faster lap times and more driver control over the car, both at high and low speeds. The final element that contributes to improved handling and grip is the downforce - using the underbody of the vehicle to facilitate airflow and “stick” the car to the tarmac.

Since the introduction of aerodynamics, automotive engineers used the distribution of downforce as the major decisive factor in car performance. Because of aerodynamic advancements, some racing cars reach cornering speeds of 4 G (four times the acceleration of gravity). The same factors that apply to racing cars also stand true for street legal vehicles. The shape of the car, the airflow created by accessories and car parts, the effect of the rear wing spoiler or frontal spoilers - all these contribute to the aerodynamic level of the car. For improved downforce, you can try several solutions, such as installing a well calibrated rear wing or lowering your car’s suspensions.

History and trends in aerodynamic development.

Modern cars are always tested from an aero dynamical point of view. Wind tunnels are used on car prototypes to see what each segment of the car does to airflow, and other tools such as computational aerodynamics and aerodynamic design and optimization are employed in order to find the best airflow solutions.

The concept of body streamlining appeared after Chevrolet-Chaparral implemented some groundbreaking airflow elements in their Can-Am cars. The rear axel of the car had a wing attached to two struts and the wing was adjustable at pit stops to tune the car for the best efficiency. The idea became very popular in a short while, and other aero dynamical improvements were soon to follow. Lateral sealing skirts were later developed and formula racers ended up reaching speeds of 1.7 G. Lotus introduced the ground effect car - the bottom part of the vehicle was shaped in such a way that the volume of downforce provided was much greater than with previous models.

Today’s cars, from a Ferrari F50 to a Smart, employ aerodynamics as an essential factor in their construction. Manufacturers focus on this aspect of car making - improved aerodynamics reduce fuel consumption, habitat noise and also provide the driver with more control and stability, thus improving vehicle safety.

Some online poker tournaments may have a deceiving allure when they are announced as deep stack or double stack events. The normal reaction would be that you’d get more play for your money in a tournament that starts with 30,000 chips than in one that starts with 10,000. There are a lot of things to factor in when determining this.

Firstly, many deep stack online pokertournaments basically just mean that they begin you with a deep stack. Having 30,000 chips at a 25/50 blind level can gave its advantages. You can decide to play a lot of hands and try and snap people off, or you can literally wait for premium hands. You have a lot of options at the beginning of a deep stack event. These options may cease to run out quickly if the tournament has a poor structure. A lot of online events will boast that they are deep stacked, but not the fact that they have turbo blinds. This means that you get a lot of play in the early stages, and when you near the middle or end of a tournament, you have very few choices available to you. Short stacks cannot wait around and are forced to make moves, and big stacks have the clear advantage of picking their spots.

In many poorly run deep stack pokertournaments, the antes arrive way too soon. I played one a few weeks ago where the antes arrived on the third blind level. After two hours and fifteen minutes of a 3-day event, antes were introduced. You could tell, the organizers of this event just wanted to get things over with. They wanted people to feel they were in a very long and slow tournament, but all of the fine details pointed otherwise.

Also, take a look at the blind schedule. Sometimes critical blind levels are skipped. This one tournament went from 600/1200, to 800/1600, to 1,000/2,000 and then jumped to 2000/4000. The whole time the big blind was being increased by 400, and all of a sudden it is being increased by 2,000, a 5x jump. While they can’t keep the increases the same for the whole tournament, this one was drastic. How about a 1500/3000 level?

So, before you cough up the extra coin to play in a deep stack tournament, make sure that the structure looks like it will also run deep and give you lots of play. Who needs lots of play on day one when you can have it around the bubble?

While a great many individuals dream of getting a degree, it is sometimes seemingly impossible to interrupt your career and or family life to go back to school. Many of us, of course, have jobs and find that the traditional schedules offered by community colleges and universities often make it impossible for us to juggle our schedules to attend. Or perhaps we have family members, kids more than likely, that we simply must dedicate our time to. These are the very things that are making online college courses ever so more attractive. And don’t think for a second that the colleges and universities across the country aren’t recognizing this and responding in kind.

A great alternative for the person who desires to attend college classes is to go the route of an online accredited degree. This is a degree from a college or university with accreditation, which means it meets the state’s guidelines and is deemed to be every bit as credible as a brick-and-mortar earned degree.

The programs offered in the form of online degrees very greatly. It is advised that anyone pursuing this avenue of higher learning do their homework and learn as much as they possibly can before making their decision as to which classes to pursue. There is ample information to be had, so by all means request as much as you feel is necessary to obtain the information that you’re after. We must remember that there are so many degrees offered through the online accreditation process that your choices are becoming ever more diversified. Degree levels include Associates, Bachelors, Masters and Doctorates.

The advantages to getting an online degree are virtually endless. You do not have to commute and there is no need to schedule classes and reshuffle your life around someone else’s schedule. The only thing you really have to do is be on yourself to stay disciplined to get your work done.

I will again repeat what I said earlier because of its great importance. It is absolutely paramount that you make sure that the degree that you are pursuing and the classes that you are taking are indeed accredited. There’s nothing worse than wasting your time and money taking classes that you will not get credit for, unless of course you are doing it for your own edification.

If you were ever considering getting a degree to improve your chances of landing a job, or getting paid more, or even to perhaps change careers completely, now is the time to do it. The future is promised to no one and now with the advantages of online accredited degrees, there really is no excuse for not pursuing these wonderful opportunities. Most of these online classes are delivered by way of computer. Don’t be intimidated by this if you are not computer savvy. A simple computer and Internet connection will be more than enough to get you through. So now you know. No excuses, get out there and get it done.

Sintilia Miecevole, host, has a site www.auniversitiesz.com with resource information from the many universities such as Standord, Cambridge and Calgary to degrees, searches and much more. Visit www.auniversitiesz.com and find the information you’re looking for!

An Associate’s degree, or a “two-year” degree, provides a valuable pathway to career enhancement, and provides an educational foundation which makes it easier to earn a Bachelor’s degree down the road. Earning an Associate’s degree online is a flexible, convenient, and innovative way to advance your career and improve your education. Traditionally, going to college requires a student to physically attend. This often requires relocating, or settling for a college because it is close to home. The advantages of technology now afford students the opportunity to attend college outside the confines of a traditional college, and earn a degree online. As the popularity of earning a degree online increases, more traditional colleges are joining online-only colleges in offering educations over the Internet, presenting students with broader educational options, not to mention flexibility and convenience.

In order to land that promotion you’ve worked so hard for, or attain the career of your dreams, it’s often necessary to have some type of secondary education. There are many advantages to earning your Associate’s degree online. Receiving your Associate’s degree online allows you to achieve your career goals at your own pace, without interfering with your current work commitments. You need not live locally to attend the college of your choosing. Attending courses and submitting coursework online eliminates the need for commuting or relocating. Convenience is another plus in earning a degree online. A college may offer more sections of popular courses at many convenient times, including nights and weekends, allowing you more options as to when to attend class. This allows you more flexibility, and is ideal if you work full time and/or care for a family. In addition, who wouldn’t find it appealing to attend college from the comforts of home?

There are many types of Associate’s degrees you can learn online. There is certainly a degree to suit every educational and professional need. Some of these programs include General Education, Information Technology, Paralegal Studies, Business, Healthcare, and various professional certificates. These are but a few of the programs available to study online. Most of these programs are offered at fully accredited colleges that are recognized by the U.S. Department of Education, which is a necessity if you have prior college credits that you wish to transfer, if you intend to continue at another college in order to receive a Bachelor’s degree, or if you want your degree recognized by your employer and any professional organizations you are affiliated with.

You might be worried about affording an online Associate’s degree. Often, financial aid is available to online students in the form of grants, loans, and even scholarships. Also, many employers may be willing to pay for part or all of your tuition and fees. After all, investing in your education is investing in the firm’s future as well.

The misconception of receiving your Associate’s degree online is that the experience might not be as enriching or legitimate as attending face-to-face classes at a traditional college. The degree programs offered online present the same opportunities for group work, independent study, and interpersonal communications as their traditional counterparts. In fact, continuing your education online might help to facilitate the learning process as well as develop time management and self-motivation skills. With the prevalence of the Internet and advancements such as teleconferencing in both education and the business world today, it is possible to come away from the experience not only with a degree, but also with greater knowledge and comfort with technology, which could prove to enhance your career as well. Receiving your Associate’s degree online is a valuable, convenient, and flexible way to broaden your career opportunities.

Learn the essential information for picking the right online degree course at www.higher-education-online.com/online-associate-degree.html

What makes us the sort of people we are? It is certainly not only our environment or our upbringing but it’s the attitudes and traits that are passed on to us from generation to generation and it’s by understanding our genealogy and family History that we come to understand ourselves.

So how do we go about doing this? The first step is to find our own birth certificate and from this we will find out where we were born, who our parents were and when they were married and so on. From our parents marriage certificate we can trace our grand-parents and again from their marriage certificate this will give where they lived, how old they were on marriage, what trade they followed and so on and then by using this information we can then find our great-grandparents and so on back into time. Also by using this information with the help of the many genealogical online sources we can trace without too much difficulty if there were children of these unions. I must add although not difficult the tracing of siblings can be very time consuming. There is certainly no royal road to success just perseverance. Further, I must admit that I have over simplified the above process for clarity as many complications can come into it such as divorce, re-marriage and so on.

However in Scotland statutory registration started in 1855 and prior to this the recording of Births, deaths and marriages was the responsibility of the church and this record is called the Old Parish Record (OPR) and the earliest known record of this dates back to 1555.

So taking Scotland as an example everybody can trace their family back to 1855 and most back to the 18th century and some to the 16th and 17th century and there are many reasons for this. In the first place the spellings of names change through time only becoming the accepted version in the later part of the 19th century but despite this various spellings of family names still exist to the day. So unless we know the form of spelling of the family name we won’t be able to find the ancestor we are looking for. A further problem is the actual record itself and that is as good or as bad as the person who originally made the record in the first place. Some Session Clerks of the Church of Scotland were first class at recording and so they will record for example, for a marriage, the names of the people being married, parents and witnesses along with their trade and where they lived etc. However in some OPR’s all we have are the names of the people being married and that is it. Apart from this records can be lost, destroyed, defaced, and can be simply wrong or confusing and if the family historian isn’t absolutely sure about how to approach or handle records this can cause no end of problems and people can be totally misled. Not only this, but couples have been married under completely false names.

Talking about marriages and the OPR. What people don’t realise is that a couple could be married according to the law of Scotland but never recorded in the OPR. The reason for this is until quite recently a person could be considered married in several different ways without a Church or Civil marriage taking place (Civil marriage was originally consented to by the granting of a Sheriff warrant) and that was by sexual intercourse, by agreement, and by habit and repute. There was also what was called an Irregular marriage which was in fact a form of fraud. The idea was to take advantage of a young lady for sex. Taking Leith as an example. Leith is a port and being a port has seen many sailors and soldiers passing through it over the years and not only this but Leith has many Public Houses. So a Sailor or Soldier visits a Public House and wants a night’s pleasure with a young lady who he fancies. The lady in question says she is respectable and would not consider sex before marriage. The Soldier/Sailor says that isn’t a problem because he had someone that could marry them there and then and so they go to the back room of the Public House where they go through a form of marriage with a so called “Celebrant” and the lady gets a certificate.

However the marriage is a total fraud and by the time the woman discovers she is expecting the Soldier/Sailor is long gone. The problem for the woman is because if she can’t produce a valid marriage certificate she couldn’t claim any help from the Parish and that is why if the fathers could be traced the Church insisted on them being properly married. So if this happened to your ancestor the record of the marriage won’t be found in the OPR but in the Kirk Session Records. In this the Church wasn’t being narrow minded it was because Edinburgh up to the beginning of the twentieth century, incredible though it may sound, the greatest cause of death was starvation and if a woman couldn’t work or get money in some way or another she could well starve to death. Forget about the Shortbread tin idea of Scotland, Kilts and all the rest of it. Scots left Scotland to go overseas because, especially in the late 18th and 19th centuries, to escape from bad housing, disease and shocking working conditions. Visit any Churchyard in Scotland that is reasonably ancient and you will find whole families wiped out by disease and want. As one writer put it writing about poverty in Scotland in the 19th century “Live in misery and die at thirty seven”

So when you come to do your family tree try to find out something of the history of the area of where they lived and if possible try to find the streets mentioned in your certificates in maps of the period in which they lived. That will help to put some flesh on the bones so to speak instead of you just having a name or a list of names.

What is most important is not to have any romantic ideas about your ancestors. They were human beings and lived within the context of their times and it would be wrong to judge them by our standards. If you wish to see what living conditions were like in the past then visit my “The History of Leith Website” at www.leithhistory.co.uk it will surprise you.

John Arthur is a local historian and genealogist,married with two sons and has websites at http://www.leithhistory.co.uk and http://www.lineages.co.uk

“The American Dream” consists of the old rags-to-riches story as pictured in the books written by Horatio Alger. The American dominant culture has tried to convince themselves and others that America is the “land of opportunity”; that if a person works hard and has “luck and pluck” that person can achieve his or her dreams of riches and success. The American Dream is not aobut equality, because it is assumed that all are equal (among the WASPs). In contrast, the African American dream is about equality and freedom.

In Martin Luther King’s famous speech “I Have a Dream,” he says “the life of the Negro is still sadly crippled by the manacles of segregation and the chains of discrimination”… “the Negro lives on a lonely island of poverty in the midst of a vast ocean of material prosperity.” These passages of King’s are evidenced in the two texts, Baby of the Family and Black Girl Lost. Although Lena’s family is not poor, they are forced by a segregated society to live in a poverty-stricken area (the Black part of town). Sandra lives in an even worse area, the African American ghetto and she is desperately poor. Sandra must steal in order to keep from starving and to go to school without being ashamed. While the American Dream involves material success, the African American dream consists of freedom and equality.

References

Ansa, Tina McElroy. Baby of the Family. Harcourt, 1991.

Goines, Donald. Black Girl Lost. Lushena Publishing, 2006.

Mary Arnold is an author on http://www.Writing.Com/ which is a site for Fiction Writing.

Her writing portfolio may be viewed at http://www.Writing.com/authors/ja77521

Dave was a young man in college, a track star on a scholarship. Dave was not like the other men on the team as he rarely dated much. One day Dave told the team he was gay. About a month later after he went home for thanks giving dinner something happened with his family and before Christmas he killed himself.

I cannot tell you what it did to his family afterwards, I guess they should have thought about it before they did and said whatever it was they said, which they never did say at the funeral. I cannot know how involved Dave really was, I am not sure if I would have ever called him gay, but he did not date any of the gals, some pretty fine ones too, were often available. Runners are know for their stamina both on and off the track so getting a young lady was never much of a challenge compared to the strenuous work outs of the team.

I think many of us always kind of wondered why Dave did not date and when we found out that he had turned gay, I do not think anybody was super surprised. I don’t think to me it really mattered, Dave was Dave and that was good enough for the team and for me. Apparently from what I have read this is not so uncommon. But it is a tragedy and it sucks big time. It is not right.

It is unfortunate that it ended this way for Dave, as he was quite the athlete, gentleman and a scholar. It might be wise if we are to careful to judge others and understand these issues more. I am not gay nor do I believe that is something I would recommend aspiring too, but rather think that everyone needs to live and let live a little. Consider this in 2006.

“Lance Winslow” - Online Think Tank forum board. If you have innovative thoughts and unique perspectives, come think with Lance; http://www.WorldThinkTank.net/wttbbs/