Archive for December, 2009

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Petrol Engine Versus Diesel Engine

December 29th, 2009

The choice between Petrol cars and Diesel cars is highly debated right from the inception of these two engine types. There have been endless discussions on this topic among car enthusiasts across the world including India. This article is dedicated to comparing these two most famous engine variations.

Differences Between Petrol and Diesel Engines

The most distinguishing feature of the diesel engine is that it uses compression ignition to burn the fuel, which is injected into the combustion chamber during the final stage of compression. In a diesel engine, fuel is injected at high pressure into the hot, compressed air in the cylinder, which causes it to burn and no spark is required for this. Thus, “compression ignition” is done rather than “spark ignition”. The petrol engine is known as a “spark ignition” engine.

The Petrol engine uses the Otto cycle in which a fuel/air mixture is ignited by a spark plug. The air and fuel mixture when ignited by a spark burns and thereby expands to force the piston down. In case of a petrol engine, fuel and air are pre-mixed usually before compression. Earlier the pre-mixing used to be done in a carburetor but now (except in the smallest engines) electronically-controlled fuel injection is used for this. The pre-mixing of fuel and air makes a petrol engine to run at a much higher speed than a diesel. However, it severely limits their compression, and thus efficiency.

Diesel engines offer better fuel efficiency when compared to petrol due to the fact that they have higher compression ratio. Another advantage is that, a diesel engine can be more easily turbocharged than a petrol engine because of the fact that if the compression ratio and the pressure in the cylinder are high during the inlet stroke, the mixture starts to burn to soon, while the piston is on its way up. The diesel engine has no fuel in the cylinder and thus allows the turbocharger to suck as much air as it can without creating any problem.

The higher compression ratio is helpful in raising fuel efficiency. Diesel engines are much more efficient than petrol engines when at low power and at engine idle. Diesel engines, unlike the petrol engine, lack a butterfly valve (throttle) in the inlet system, which closes at idle. This creates parasitic loss and destruction of availability of the incoming air, reducing the efficiency of petrol/gasoline engines at idle. This mechanism makes the diesel engine an attractive choice for many. Diesel engines are left idle for many hours or sometimes days in many applications, such as marine, agriculture, and railways. The engines are more efficient when compared to petrol engines of the same power. They consume significantly lower fuel and offer better mileage.

A diesel engine can relatively last longer, due to the fact that petrol destroys lubrication and diesel doesn’t. While all the above support diesel engines, a major advantage of petrol engines is that they are relatively lighter than diesel engines. Engine weight is an important factor which affects speed and performance of a car. This is one of the reasons why some of the fastest cars in the world run on petrol. It should be noted that even though diesel engines are heavier and make the automobile heavy, they have more torque.

Engines and Emissions

Diesel engines consume around 30% less fuel than petrol engines and this results in much lesser carbon dioxide emissions. The diesel engines produce virtually no carbon monoxide and are much safer than petrol engines. Tests done on car emissions reveal that while Nitrogen Oxides are higher in a new diesel engine when compared to a new petrol engine. But by the time they cover 50,000 miles or so, they are the same and after that the petrol engine produces more Oxides than the diesel engine. Hydrocarbon emissions contained in petrol engine emissions are considerably more than that in diesel engine emissions. However, diesel is certainly more dangerous from the point of view of Suspended Particulate Matter (SPM). SPM refers to solid particles suspended in open air, such as soot generated by combustion of various fuels. They might cause respiratory problems because of their tendency to deposit themselves in the lungs. Though much has been done to improve the fuel efficiency and reduce emissions from the petrol engine, still more needs to be done.

In India, diesel is much cheaper than petrol. Ironically, diesel cars are more expensive than petrol cars.

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Engineered Food and the Fda

December 21st, 2009

To get bioengineered medicines, grains, vegetables, and animals on the market for human consumption, U.S. biotech companies must pass their products through the Food and Drug Administration (FDA).

Recently, the FDA has been in the news because its Prescription Drug User Fee Act of 1992, which forces drug companies to pay in to expedite drug approval, came up for renewal. That same year, the FDA rejected mandatory labeling of genetically modified organism (GMO) products. How might the FDA affect the future of bioengineered food?

The User Fee Act has, in Harvard professor Jerry Avorn’s opinion, “pretty much transformed the FDA. The sense now is we report to the industry; they pay our salaries; we had better be quick on these approvals.”

Some biotech products will zoom through the FDA because they are advances in medical treatment, and, of course, we all want the sick to get the best new therapies. The problem is that the FDA is underfunded, so most resources are dedicated to medical advances. Thus, according to David Kessler of the FDA, “other parts of the agency—post-market surveillance, food safety, the field resources—those areas of the agency suffer.”

In addition, the FDA is essentially rubber-stamping the tests performed by each company that has developed a product, and since they’re bogged down in analysis of drug tests, they hardly ever follow up on the market to see if bioengineered products are having a negative impact on consumers. One publicized mishap in 2000 resulted in traces of StarLink Bt10 corn, meant only for industrial purposes, cross-pollinating with conventional corn and winding up in taco shells. We know the FDA isn’t catching problems like this one–and that, as yet, consuming products deemed marginally unsafe won’t cause an epidemic—but eventually the biotech industry may get consumer backlash for causing a serious problem that could have been avoided if the budget were expanded.

I should probably note that the U.S. Department of Agriculture (USDA) oversaw the restrictions on this brand of corn, and the Department of Health and Human Services, of which the FDA is a part, only posts notices for products consumed by humans—so there’s a further complication for biologically engineered products. They may be subject to these two departments as well as the Environmental Protection Agency, and this structural weakness probably doesn’t make for excellent communication.

One could argue that GMO labeling is only a minor issue in the U.S. and that the average citizen isn’t too concerned about the provenance of his or her food. There are at least two problems with this attitude. The first is that U.S. exports will be increasingly suspect to foreign markets, particularly the EU, which require labeling and stringent testing. The second is that any misstep, such as a genetically engineered product that results in widespread sickness, will create distrust of the FDA and bioengineering in general.

Europe’s vigorous standards regarding approval, track-back, and isolation for GMO crops may be driving North America out of the market. Agricultural specialists like Dan McGuire are questioning if GMO crops are really to their economic advantage.

“I can’t recall any foreign or domestic corn customer ever requesting that U.S. farmers start planting and supplying genetically engineered corn. So the introduction of GMOs was not a response to importers or consumers requesting such a change. Indeed, it’s a direct result of biotech companies introducing those products into the domestic and foreign market without market research on consumer acceptance. Indeed, the first I heard about GMOs was from European importers,” said McGuire.

Leaders in the biotechnology industry need to be activists for their products—labeling their products will bring them one step closer to informing the public and leading us into discussions of benefits like cheaper crop production and less pesticide runoff.

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Graduate Chemical Engineers Jobs – Creating Industrial Processes

December 14th, 2009

There has been a steady amount of engineering graduates in the United Kingdom and Europe over the last decade. As such, the job market for chemical engineers and other engineering specialists has been static. Job demands have been met by university outputs, though the dwindling number of engineering graduates means that the market for chemical engineers favours new graduates. University students are choosing non technical areas of study, avoiding engineering and the sciences in favour of business administration and liberal arts degrees. There are plenty of jobs available for chemical engineers in the UK and Europe, as well as plenty of jobs on the international level for these graduates.

Chemical engineers are needed in a variety of industries, with the market promising for graduates over the next ten years. Automotive companies are always looking for chemical engineers to create the production processes for auto paints, sealants, and engine fluids. Pharmaceutical companies need chemical engineering graduates to help create efficient chemical processes in the creation of prescription drugs. Chemical engineers are also needed in the water treatment, agricultural, and marine industries for a variety of production and troubleshooting tasks. Chemical engineers will also be needed for the expansion of industries, since these engineers help control the efficient manipulation of raw materials into usable products.

Manufacturing companies and other businesses looking for chemical engineers expect excellence in the academic side of chemical engineering from all applicants. The qualified chemical engineer will be able to demonstrate their technical, communications, and creative abilities to a potential employer. Chemical engineers need to know advanced methods of combining chemicals to create a useful production process. They also need to be able to use a mixture of traditional production methods and cutting edge techniques to create a dynamic production system. Chemical engineer graduates also need to be able to communicate to production staff, managers, and executives effectively in order to maintain daily production quotas. Finally, chemical engineers need to be creative in order to think of theoretical and practical chemical processes in terms of how it will influence their company’s performance.

Chemical engineers need to consider their options before jumping into their first postgraduate positions. The number of positions available to engineering graduates is plentiful in the European continent but not all positions are equal. Engineering graduates who want a quaint work experience should consider a job with a small agricultural firm. Other chemical engineering aspirants who want considerable advancement opportunities should work with international automotive companies.

Rupal Patel is the Marketing Manager at JustClick, who are a leading source of Graduate Jobs and Graduate Careers, also offering a Graduate Lifestyles portal with news and reviews on current affairs.

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