Thermodynamics is the study of relationship between energy and entropy, which deals with heat and work. It is a set of theories that correlate macroscopic properties that we can measure (such as temperature, volume, and pressure) to energy and its capability to deliver work. A thermodynamic system is defined as a quantity of matter of fixed mass and identity. Everything external to the system is the surroundings and the system is separated from the surroundings by boundaries. Some thermodynamics applications include the design of:
air conditioners and refrigerators
turbo chargers and superchargers in automobile engines
steam turbines in power generation plants
jet engines used in aircraft
Zeroth Law of Thermodynamics
The zeroth law of thermodynamics states that when two bodies have equality of temperature with a third body, they in turn have equality of temperature with each other. All three bodies share a common property, which is the temperature. For example: one block of copper is brought into contact with a thermometer until equality of temperature is established, and is then removed. A second block of copper is brought into contact with the same thermometer. If there is no change in the mercury level of the thermometer during this process, it can be said that both blocks are in thermal equilibrium with the given thermometer.
First Law of Thermodynamics
The first law of thermodynamics states that, as a system undergoes a change of state, energy may cross the boundary as either heat or work, and each may be positive or negative. The net change in the energy of the system will be equal to the net energy that crosses the boundary of the system, which may change in the form of internal energy, kinetic energy, or potential energy. The first law of thermodynamics can be summarized in the equation:
Second Law of Thermodynamics
The second law defines the direction in which a specific thermal process can take place. The second law of thermodynamics states that it impossible to construct a device that operates in a cycle and produces no effect other than the transfer of heat from a cooler body to a hotter body. The second law of thermodynamics is sometimes called the law of entropy, as it introduces the important property called entropy. Entropy can be thought of as a measure of how close a system is to equilibrium; it can also be thought of as a measure of the disorder in the system.
Vapor Compression Refrigeration Cycle
One of the applications that involves thermodynamic principles is the refrigerator. The figure below is a schematic diagram of the components found in a typical refrigerator.
The refrigerant enters the compressor as a slightly superheated vapor at a low pressure. It then leaves the compressor and enters the condenser as a vapor at some elevated pressure, where the refrigerant is condensed as a result of heat transfer to cooling water or to the surroundings. The refrigerant then leaves the condenser as a high-pressure liquid. The pressure of the liquid is decreased as it flows through the expansion valve and, as a result, some of the liquid flashes into vapor. The remaining liquid, now at a lower pressure, is vaporized in the evaporator as a result of heat transfer from the refrigerated space. This vapor then enters the compressor.
Reversibility
A reversible process for a system is defined as a process that, once having taken place, can be reversed and leaves no change in either system or surroundings. The difference between a reversible and an irreversible process can be illustrated with the example below.
Suppose a gas under pressure is contained in a cylinder fitted with a piston. The piston is locked in place with a pin. If the pin is removed, the piston is raised and forced abruptly against the stopper. Work is done by the system during this process because the piston has been raised by a certain amount. If the system has to be restored to its initial state, force has to be exerted on the piston until the pin can be reinserted. Since the pressure on the face of the piston is greater on the return stroke than on the initial stroke, the work done on the gas is greater on the return stroke than the work done by the gas in the initial process. This caused an amount of heat to be transferred from the gas to the surroundings in order that the system have the same internal energy. The fact that work was required to force the piston down and that heat was transferred to the surroundings during the reverse process makes the system an irreversible process.
Another system has a number of weights loaded on the piston at the initial state. The weights are removed from the piston one at a time, allowing gas to expand and do work in raising the weight remaining. If the process is reversed, the weight can be placed back onto the piston without any work requirement, as for each level of the piston there will be a small weight that is exactly at the level of the platform. Such a process is a reversible process. There are many factors that render a process irreversible, such as friction and unrestrained expansion.
Thus, to summarize, reversible systems occur in situations when the system is essentially in equilibrium during the transition and at each step, and only an infinitesimal amount of work would be necessary to truly restore equilibrium.
Often I am concerned when I find that government bureaucrats, academics, and politicians assume that they are so wise, that they can create a business, which will automatically make money. Indeed, I find this fascinating because, more often than not they have no-experience in business. As a taxpayer, I worry when politicians and such think they can borrow the power of the free-market, modify regulations, put forth subsidies, and then march ahead with their pet projects.
Oh it's always in the name of a good cause, just as the "road to hell is always paved with the greatest intentions." I have an acquaintance who tells me the way to innovate is through government-private sector-academia-corporate partnerships, he swears by them. And yet, every time he gives me an example, all I see is waste, inefficiency, and silly mistakes that entrepreneurs using their own money would have seen coming a mile away.
There was an interesting article in the New York Times titled; "Batteries in Electric Cars Examined After Chevy Volt Fire," by Nick Bunkley on November 11, 2011. The article stated that;
"The US has put billions of dollars into programs aimed at promoting battery and electric-car manufacturing. The large, high-voltage batteries used in plug-in vehicles can be more easily damaged in a crash than traditional car batteries and create more potential to electrically shock occupants and rescuers. The Volt's 400-pound, T-shaped battery extends under the middle of the car and between the back seats rather than fitting under the hood with the engine of a gas-powered vehicle."
The article also noted the spontaneous fires in laptops with ion-lithium batteries as well. Okay so, my comments here as an automotive industry consultant is best summarized with a joke;
"Well Thank God It Wasn't a Hydrogen Car Then!"
"Sounds like a rolling Hindenburg Disaster to me!"
Look anytime you have new technology you are going to have challenges, for instance the Boeing 787 carbon composite airliner, it was delayed for 3-years as they worked though the bugs to make it perfectly safe, see that point? But still, I want to remind folks on this Chevy Volt, that we should have expected it to "flop" because anytime the government gets involved, subsidizes an industry, company, or their products, you can bet there will be problems; Solyndra for instance.
Okay so, let this be a lesson to all. And let's get government out of business, and out of the game of crony capitalism using our taxpayer's money. We don't need any more spontaneous combustions in the free-market place, we are dealing with enough blow-back from previous such mistakes as it is. Please consider all this and think on it.
Lance Winslow has launched a new provocative series of eBooks on Future Concepts. Lance Winslow is a retired Founder of a Nationwide Franchise Chain, and now runs the Online Think Tank; http://www.worldthinktank.net
Article Source: http://EzineArticles.com/?expert=Lance_Winslow
Article Source: http://EzineArticles.com/6688153
Entering the world of Dr Arnold Klein is an extraordinary experience.
That it happened in the slightly unreal setting of the glitzy mansion where they film 'The Real Housewives of Beverly Hills' was somehow fitting.
Dr Klein has been dermatologist to the stars for decades, medical royalty in a place where the search for youth and beauty is part of everyday life.
He can claim friendships with everyone from Elizabeth Taylor down - but it is his relationship with the star he calls his best friend that has put his reputation in the spotlight now.
His treatment of Michael Jackson has loomed over the trial of Dr Conrad Murray as the defence team have tried to push some of the blame for the pop superstar's drug issues on to Dr Klein.
He was not called to give evidence so agreed to speak to Sky News to defend himself against the allegations made in court.
And that's how we ended up under the chandeliers in the rarified atmosphere of a Beverly Park mansion on a chilly Friday evening.
Heiress and reality TV star Adrienne Maloof-Nassif and her plastic surgeon husband Paul Nassif were throwing a red-carpet party to mark the opening of Dr Klein's new offices.
The guest list included the likes Charlie Sheen, who married in the house three years ago, Warren Beatty and the Earl and Countess Spencer.
It is evident Dr Klein has some powerful and influential friends and clients - and a lot of them are willing to fight his corner right now.
We were pointed to testimonials from Sharon Stone and Carrie Fisher (pictured above with Jackson and the doctor). A friend of Dr Klein told me: "He is a truly nice person, a good friend to Michael and a truly amazing doctor."
The 66-year-old has some trouble walking due to a skiing accident but he made his way to the mansion's study to sit in a throne-like chair and talk about Jackson, Murray and his own reputation.
It is clear he is bothered by the allegations made in court, the use (misuse, he says) of his medical records, and by the damage being done to Jackson's memory.
He says he would never have done anything to harm the star and that he was merely putting right the wrongs done by others over the years.
He speaks lovingly of Jackson's three children - and then raves about his affection for the 'Queen of England' - it is obvious he is a man who relishes telling a story.
We departed before the celebrity party was in full-swing - crossing paths with a few Hollywood beauties of the 70s and 80s - to reflect on this strange twist.
Michael Jackson had just two doctors in the final months of his life - their predicaments are very different right now but both will be forever linked by the controversy over his death.
Jason Thomas Scott, who is charged in Prince George’s County in a grisly double homicide and who is suspected in other killings, was convicted Monday in federal court in Greenbelt on charges of committing a series of armed home invasions, molesting a teenage girl, stealing and selling firearms and other crimes.
After deliberating for about eight hours over two days, the jury of 11 men and one woman convicted Scott of each of the 11 offenses he was charged with.
Scott, 28, did not outwardly react as the verdict was read.
Maryland U.S. Attorney Rod J. Rosenstein, who helped prosecute Scott and delivered the government’s closing argument, said Scott faces a mandatory minimum sentence of 97 years in prison for the firearms and sexual molestation convictions.
“He’s a very dangerous man,” Rosenstein said after the verdict was announced. “Prince George’s County is much safer now that he’s off the streets. He became more brazen over time, going from burglaries to armed home invasions.”
Scott’s defense attorney, Kobie Flowers, declined to comment.
U.S. District Judge Peter J. Messitte scheduled sentencing for Oct. 31.
During a three-week trial, Rosenstein and Assistant U.S. Attorney Stacy D. Belf presented a raft of circumstantial evidence showing that Scott committed a series of violent crimes in 2008 and the first half of 2009. Most of them occurred in the Largo neighborhood where Scott lived at his mother’s home.
Victims of four home invasions testified for the government, but were unable to identify Scott. The attacker or attackers wore black masks which covered everything but their eyes, the victims testified.
But two accomplices testified that they had committed armed home invasions with Scott, and that he had planned the crimes and gave the orders.
One of the co-conspirators, Marcus D. Hunter, 25, testified that Scott was methodical in choosing which homes to attack and in covering his tracks.
Scott, who worked as a clerk at a UPS facility in Largo, used a computer there to scout target homes, Hunter testified. He looked for homes whose owners owned small businesses, according to court testimony.
In executing the home invasions, Scott wore gloves and a handgun in a belt holster, and carried a police scanner to listen for signs that officers were nearby, Hunter testified.
Scott was also methodical about not leaving evidence, going so far as to mop the floor of one victims’s home so that no shoe prints were left behind, according to court testimony.
Hunter testified that he and Scott burglarized a Carroll County gun shop in May 2009 and tried to sell some of the dozens of handguns, shotguns, rifles and Uzi-style assault weapons they took, Hunter said.
But their buyer turned out to be an informant, and agents with the Bureau of Alcohol, Tobacco, Firearms and Explosives launched an investigation.
Hunter has pleaded guilty to two firearms offenses and testified for the government under a plea deal in which he hopes to gain leniency at sentencing.
Flowers said in his opening and closing arguments that the testimony of Hunter and another accomplice was not credible.
But Scott provided some of the government’s best evidence — a series of confessions he made during three meetings with ATF agents. He provided a typed list of addresses of 28 homes he had burglarized and nine he had invaded; investigators learned that each home had been hit, Rosenstein said.
Flowers said in his opening and closing arguments that Scott “exaggerated” his criminality because he was struggling with his identity as a gay man.
In addition to the federal conviction, Scott is scheduled to be tried for murder in Circuit Court for Prince George’s in November in the killings of Delores Dewitt, 42, and her daughter Ebony, 20. Their burning bodies were found inside a stolen car that had been set on fire in Largo on March 16, 2009.
According to police, Scott is also a “person of interest” in the Jan. 16, 2009, slayings of Karen Lofton, 45, and her daughter Karissa, 16. They were shot inside their locked Largo home. Police have said that Scott is also being investigated for a 2008 killing in which a woman in Bowie was shot in her home, which was then set on fire.
source : http://www.washingtonpost.com/local/jason-thomas-scott-convicted-on-federal-counts-to-be-tried-in-pr-georges-double-murder/2011/07/18/gIQAXyyfMI_story.html
