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Mechanical Engineering. 1998;120(07):56-58. doi:10.1115/1.1998-JUL-1.
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This article highlights the various processes involved in shipbuilding such as design, production planning, material sourcing, and outfitting. Since the program’s inception, Newport News Shipbuilding (NNS), has leveraged its computer-aided- design, -manufacturing, and –engineering (CAD/CAM/CAE) system and IT infrastructure to successfully revitalize its engineering environment and remain profitable in a rapidly changing marketplace. NNS engineers perform all of their ship product modeling using a proprietary program called VIVID, a design system that enables users to concurrently design structures in a multidisciplinary environment. As part of the continuing effort to develop its IT infrastructure and automate production processes, NNS has invested $60 million in upgrading its engineering design systems and automating manufacturing facilities with advanced material-handling systems, robotic cutting work cells, and robotic welding work cells. NNS is also transitioning its product-modeling systems from a Unix workstation environment to Windows NT platforms based on Microsoft’s ActiveX and COM technologies.

Commentary by Dr. Valentin Fuster
Mechanical Engineering. 1998;120(07):60-62. doi:10.1115/1.1998-JUL-2.
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This article reviews that advances in manikin software have enabled engineers to consider a fuller spectrum of user interactions with virtual products. It has been 15 years since Sammie—a computer model of a human or manikin—emerged from the research labs of Nottingham University in the United Kingdom, promising human-factors (HF) engineers a supporting software tool to improve the study of human elements of product design. Although Sammie incorporated accurate anthropometric data and representative joint constraints, the software was very difficult to use, could not import models from a computer-aided-design (CAD) system, and was not dynamic. After phase 1 of the collaborative project, Rolls-Royce and VSEL expanded their study to evaluate the use of virtual reality for the design and layout of larger and more complex machinery spaces. This second collaborative effort had several objectives: to understand how virtual-prototyping technology could help designers better visualize complex designs, design for ease of assembly and maintenance much earlier, train maintenance engineers, and enhance communications between disparate project teams, customers, and suppliers.

Commentary by Dr. Valentin Fuster
Mechanical Engineering. 1998;120(07):64-67. doi:10.1115/1.1998-JUL-3.
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This article discusses that by most measures, the last few months have been good for the rapid prototyping (RP) industry. Worldwide system sales continue to grow as the technology finds greater application in many countries, including Canada, Hong Kong, India, Italy, Malaysia, Taiwan, and the United Kingdom. During the same period, the rate at which RP-related Us patents were issued accelerated to more than one per week, according to a study by Chatham Research of Amherst, NH. In recent years, researchers have also been working on solid-form fabrication (SFF) techniques to construct prototype and production tooling, even for precision metal parts, an advance that would truly revolutionize the manufacturing industry. Of particular interest to manufacturing engineers is the continued evolution of rapid tooling (RT) technologies—methods to swiftly fabricate prototype and production—grade tooling for manufacturing processes such as plastic injection molding.

Commentary by Dr. Valentin Fuster
Mechanical Engineering. 1998;120(07):68-69. doi:10.1115/1.1998-JUL-4.
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This article focuses on a high-resolution digital camera that provides fast, flexible imaging for photomicrography and microscopy. Digital images are not only equal in quality to traditional images, but they are also three times faster to acquire, less expensive, easier to distribute, and more useful as reference images for future analysis. In terms of quality, the basic issue is matching images on 4-by-5-inch instant film, and recording the same field size with the same resolution. Reports with embedded digital image links are issued over the LAN so users do not have to seek out images separately on the Technology Center server. The department is also creating a reference library of microstructure images that have been captured digitally. Image Central software from Advanced Imaging Concepts in Princeton, N.J., is to be used to create the database with reference images and associated data.

Commentary by Dr. Valentin Fuster
Mechanical Engineering. 1998;120(07):70-71. doi:10.1115/1.1998-JUL-5.
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This article highlights the preparation of finite element models for analysis that is being increasingly automated, with new developments expected to greatly advance the field. The key to an efficient finite-element analysis (FEA) is frequently an effective finite-element mesh. The construction of this mesh is the first step in the analysis process. Structured grids, as is implied by the name, have a clear structure. The techniques used to generate them produce quadrilateral or triangular cells, or elements, in two-dimensional analysis, and tetrahedral or hexahedral elements in three-dimensional simulations. An area of great potential is the automatic adaptation of the mesh, without intervention by the analyst, and automatic continued solution until the required accuracy has been reached. To effectively automate the choice of the mathematical model and its solution, major advances in theoretical issues and software development are still required and will provide an exciting challenge for the years to come.

Commentary by Dr. Valentin Fuster
Mechanical Engineering. 1998;120(07):72-73. doi:10.1115/1.1998-JUL-6.
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This article reviews that twenty-first century passengers on the Royal Caribbean International and Celebrity Cruises are set to make history in style. Up to six of Royal Caribbean’s Voyager- and Millennium-class vessels will be the first cruise ships ever powered by General Electric’s gas turbines. In addition to reducing engine-room noise and vibration and cutting emissions, this propulsion system—a departure from the traditional diesel engine—will make it possible for ships to set sail with a reduced maintenance crew and smaller parts inventory. Royal Caribbean International currently operates a fleet of 12 ships. In the Royal Caribbean application, the GE gas turbine will be used to drive generators that will provide electricity to propeller motors. The steam turbine will recover heat from the gas turbine exhaust for other uses. This combined gas turbine and steam turbine integrated electric drive system represents a departure from diesel engines in more than one respect.

Commentary by Dr. Valentin Fuster
Mechanical Engineering. 1998;120(07):75-76. doi:10.1115/1.1998-JUL-7.
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A product called Design Suite by In Part, Saratoga, CA, promises to reform design catalogs upright, creative, and efficient. Pro/ENGINEER models are fully parametric and include envelope dimensions and embedded parameters, such as mass properties and part number. InPart also includes Virtual Reality Modeling Language (VRML) models that enable users to view the part in three dimensions before downloading it. InPart says that every model goes through a quality assurance check to ensure that it represents a repeatable, detailed, and accurate model. Then the manufacturer conducts a review. Finally, InPart conducts a second check. InPart also offers Alert Assurance, a notification system that sends e-mail to alert customers to changes in a part they have used and asks if they would like an updated part. Manufacturers are said to be contractually obligated to notify InPart, even before their own customers, of product changes, so InPart's customers are the first to know about a product change.

Commentary by Dr. Valentin Fuster
Mechanical Engineering. 1998;120(07):78-80. doi:10.1115/1.1998-JUL-8.
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This article explores use of foil air bearings in land-based turbomachinery. A machine with foil air bearings is more reliable than one with rolling element bearings because it requires fewer parts to support the rotative assembly and needs no lubrication. Foil air bearings can handle severe environmental conditions such as the ingestion of sand and dust. A reversed pilot design at the cooling flow inlet prevents large particles from entering the bearing's flow path, and smaller particles are continually flushed out of the bearing by the cooling flow. Many applications of foil air/gas bearings other than air cycle machines have been built and successfully tested, but nothing appears to be currently in production. Foil bearings have strong potential in several applications. Among these are small general aviation gas turbine engines; oil-free cryogenic turboexpanders for gas separation plants; auxiliary power units for various aerospace and ground vehicles; and, taking advantage of automated manufacturing methods, automotive gas turbine engines, vapor-cycle centrifugal compressors, and commercial air/gas compressors.

Commentary by Dr. Valentin Fuster

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