I don't want to discredit the work of the American scientists, but what the French president was referring to was the energy consumed by the people, not by the scientists doing the research.

Take cars, for example. American manufacturers build cars that have extremely large engines and burn large amounts of fuel (for example, a 4.0-liter, 6-cylinder engine), while cars manufactured by the Europeans and the Japanese consume far less fuel (e.g., a 2.0-liter, 4-cylinder engine) and produce about the same horsepower. This shows that the engines designed by American car manufacturers are not efficient.

Another point is the effect the Kyoto Protocol has on the U.S. economy. What people seem to forget is that the European economy is greatly affected by the U.S. economy because the markets are linked, so there is no European conspiracy to destroy the U.S. economy.

It is my understanding that one of the benefits of diesel engines is that the fuel/air ratio does not need to be controlled as precisely as in a gasoline engine. This is because diesel fuel is ignited by the heat of compression of the fuel/air in the cylinder. Somewhere in the compression stroke the mixture/compression is just right for any amount of fuel to ignite. A diesel cylinder should need only a drop or so of fuel to keep it idling.

Granted, there are 8, 10, or 12 cylinders and who knows how many thousands of diesel trucks in the world idling, but the amount of fuel used per truck at idle is not nearly as wasteful as a gasoline engine at idle (or so I've learned).

It is a tremendously powerful feeling as a design engineer to have such tools at my disposal, knowing what I had in 1985. However, I would like to point out that there is a cost associated with using these tools.

For example, training personnel to use these systems now takes potentially productive design time. Say, on average, four weeks initially and two weeks per year thereafter just to keep up with the technology for every person using the software.

The drafting skills you learned in school were almost universally applicable to any first job. Now there exists a loss of process uniformity. The CAD package you learn in school carries weight in the balance of which companies are interested in you as an employee.

Engineering software has also mutated from being either an automated graphical extension or coded program to an expert system acting as co-designer, co-manufacturer, and co-engineer in many instances. This has enabled one man to do much more, but has also made the entire design process much more dependent on one man. Coupled with this is the capacity for people to perform analytical tasks that they can neither explain nor defend.

The initial assumptions and postprocessing data analysis that go along with a proper FEA analysis often don't make it to a design review. Instead, color graphs depicting stress, deflection, or strain are provided as justification to decision makers often unfamiliar with all the user input possible in a program. This point is discussed admirably in Finite Element Analysis by Vince Adams and Abraham Askenazi.

Finally, there is the mother of all ignored time-wasting issues: compatibility. All other components, such as hardware devices, network software, rapid prototype devices, and CNC machines, are intolerant of anything but perfect communication from software.

Add to this the cost of highly specialized and expensive IT people needed to support both people and machines, and the true cost of using complex CAD packages begins to unfold.

CAE/CAD software is just a powerful tool to be used in conjunction with training, experience, technical literature, resource management, and other traditional engineering project components with the ultimate goal of increased design process efficiency.

Being an engineering practitioner of a Third World developing country, with no prominent position in the manufacturing-design stage (as those of the United States, Japan, or Europe), but in technology use and adaptation, one must get used to both metric (SI) and the U.S. customary system (USCS), since one must deal with machines from almost every developed country.

Our teachers did their best to make us think in SI units, and tried to make us forget the USCS, although they all agreed it would take a lot of time before we no longer use the U.S. system. The reason? Well, there is a lot of technology that comes from the United States, where engineers have been using the USCS system since the very beginning of the industrial revolution.

Personally speaking, I prefer the SI system. I was trained to think like that, for example, by associating 1 newton (1N) with the weight of an apple in my hand. I find it very difficult to think 1/2 inch, 1/4 inch, 15/64 inch, etc., especially when it comes to using a gauge for measuring pieces and machines. I prefer to use the Celsius scale rather than the Fahrenheit, or the pascal instead of psi for pressure and stress measuring.

However, I agree with Dehesh in the very suitable use of the USCS in some fields of engineering, such as in HVAC systems for the sake of facility.

I think it is a matter of good scientific notation to become able to think in MPa, km, kg, etc. I look forward to the day when one does not need to carry a conversion table, and to the day our country stops suffering its internal violence and poverty, and external sorrow, reproaches, and even condemnations.

That day, our government might stop its expenditures on helicopters and ammunition, and might begin to invest in education, research, and development, which would allow us to become a better country by building our own technology.

Jordan asked about industry standards or publications that deal with cargo damage, especially lightweight cargo, as related to truck and trailer suspensions.

Air suspensions have been in widespread use for several decades on trucks and trailers, and one of the primary features is the ability to adjust to changes in load by increasing or decreasing air pressure to maintain constant ride height. The result is a spring rate that increases with load to provide a nearly constant natural frequency. Good vibration isolation is thus obtained over a wide load range.

For the lightest of loads, and depending upon the particular truck and trailer supension designs in question, the vibration isolation provided by today's air suspensions may not be sufficient to protect all cargo for all road conditions. There's always room for improvement, and the trucking industry can be expected to respond to customer demands.

SAE has a few publications that may be of interest: Riding on Air—A History of Air Suspension, by Jack Gieck, Society of Automotive Engineers Inc., 1999; and SAE Manual for Incorporating Pneumatic Springs in Vehicle Suspension Designs (SAE HS-1576), Society of Automotive Engineers Inc., 1994.

Editor's Note: The writer is senior development engineer for air springs at The Goodyear Tire & Rubber Co.

However, the legal system, attorneys, and, in this case, professional engineers get a bad rap for doing what we citizens allow them. Verdicts are issued by juries made up of citizens selected by both sides of a lawsuit. Attorneys do not issue verdicts, nor do engineers or witnesses. Let us blame any injustice on the jury, effectively on the public as a whole.

I liked the article. Actually, I didn't realize that such an article was necessary. In academia I find just the opposite attitude. Students would prefer to stay away from the English system because of the conversion factors needed.

Even so, it isn't that much more work to learn both systems, especially since we don't need to learn a second language (though that's not a bad idea either).

As my instructors in England 57 years ago never tired of telling us, "Don't confuse work and torque." 33,000 ft.-lbs. of work/minute is 1 horsepower, whereas 33,000 lbs.-ft. of torque x 1 rpm is 6.28 horsepower. Torque can exist without doing work, and the time-honored method of differentiating the two is to use distance-force for work, and force-distance for torque. Newton-meters follows this rule correctly, but the English units shown do not.

We are a vast and diverse nation of many people. To presume that we can all agree on what should be taught to our kids at any instant seems both ambitious and unrealistic. And expecting that some august group of experts or the folks in Washington will know what to do depends on your point of view. Advocating what I think is best may heal the wound, but not the body.

There is no subject or cause that is superior, nor one that can be sacrificed for the sake of others. And there is no one more able to help and inspire children and guide them in the proper direction than their parents. To me, it seems, there is no better way to help both parties lay a basic foundation than to allow them the opportunity to choose for themselves what is important and the power to seek the education they desire.

I don't have the answer, but I challenge all of us to work together to find one. If we can leave footprints on the moon, we can do anything.

Take this simple example, using the formula for bending stress:

S= MC/ I

If M= 100,000 ft.-lb.

   C = 6 in.

    I = 4000 in.⁴

Substituting the values directly into the equation,

S= MC/I = 100,000 ft.-lb./4,000 in.⁴ x 6 in.

The units are as important as the numbers.

To express the above fraction in more conventional terms, remember that 12 in. = 1 ft., and that we may multiply the numerator and denominator by equivalents without changing the value:

S= 100,000 ft.-lb. x 6 in./4,000 in.4 x 12 in./1 ft.

which simplifies to 1,800 lb./in.²

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