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Mechanical Engineering. 2007;129(01):24-29. doi:10.1115/1.2007-JAN-1.
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This article focuses on the developments in materials, production methods, and turbine designs that have spawned a new class of jets. Cessna’s Citation Mustang became the first very light jet to reach commercialization. According to market leaders, the development of computerized cockpits with simplified displays has also been huge. Composites also let engineers combine lots of parts—panels, framing, rivets—into a single part. The fewer parts, the easier and cheaper it is to assemble and the more reliable the finished airplane. Every aerospace company is looking for bolt-on components that simplify assembly and maintenance. Adam Aircraft seeks to simplify production by making large composite parts. The second mechanical advance that makes very light jets possible is the compact, reliable turbofan. While Pratt is well-known for huge turbines that power commercial passenger jets, the company produces several small turbines. Pratt uses blisks and other technologies to simplify production. The result is a new type of jet, one that makes jet airplanes far more affordable.

Commentary by Dr. Valentin Fuster
Mechanical Engineering. 2007;129(01):30-32. doi:10.1115/1.2007-JAN-2.
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This article describes various engineering ways to use computers in manufacturing industry. Streamlining computer-aided design (CAD) and computer-aided manufacturing (CAM) handoff has long been the dream of engineering organizations that face handoff issues every day. The company, Protomold Co. Inc., ties CAD directly with CAM, to do away with requiring a human in the loop. It makes plastic injection-molded parts from customers’ CAD models. A Minnesota company has nearly automated its mold making. Software designs the mold automatically and automatically commands milling machines. The article also highlights that CAM systems of the future should include easy workarounds that any company could use to customize the software. Like other computer-aided engineering applications, manufacturing software is being pushed forward, although innovation and research is mainly the purview of academics. Researchers are focusing on considering rapid prototyping for making CAD and CAM work together in future.

Commentary by Dr. Valentin Fuster
Mechanical Engineering. 2007;129(01):34-37. doi:10.1115/1.2007-JAN-3.
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This article discusses design and developments in the refrigeration and compressor fields to deal with Montreal Protocol’s announcement of expiration of R-22 as refrigerant. The Montreal Protocol dictates that by 2010 no new refrigerators or air conditioners will use R-22, a hydrochlorofluorocarbons (HCFC), as a refrigerant. The replacement, known as R-410A, is an HFC (hydrofluorocarbon) rather than an HCFC. Jim Crawford, director of regulatory affairs at The Trane Co., a heating and air conditioning company in Tyler, Texas, said that industry is adopting R-410A primarily in air conditioning. Companies like Trane have used the time allotted by the Montreal Protocol to design, test, and build R-410A equipment for 2010. Compressors have had to be optimized both for the refrigerant and the application. Since the heat characteristics are different between the two refrigerants, heat exchangers must be made larger or smaller. Many new air conditioners, like Trane’s XL16i, already use R-41OA, which contains no chlorine.

Commentary by Dr. Valentin Fuster

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