Advanced Design Concepts Research Articles

Bipolar Plate-Supported Solid Oxide Fuel Cells for Auxiliary Power Units

ABSTRACTThis paper presents an advanced design and fabrication concept for a solid oxide fuel cell (SOFC). The concept is based on a laminate repeat unit comprised of a thin electrolyte, cermet anode, metallic gas flow fields, and a metallic bipolar plate. The laminate is sintered in a singlestep process in a controlled atmosphere, and the cathode is applied and sintered in situ during the initial heating of the cell (or stack). Observations about the types of cracks that formed in the electrolyte during the sintering process guided the development of the sintering protocol to yield the desired product. Cells with power densities exceeding 250 mW/cm2 have been tested.

Exacting Standards

This article discusses integration of handcrafted parts into computer-aided design (CAD)-designed bikes. The digital duplication process started when Harley Davidson sent Schaefer an assembly-ready Dyna Wide gas tank. It took two days of work to prepare the tank and scan it with an ATOS white-light 3D scanner, made by GOM mbH (for Gesellschaft fur Optische Messtechnik) in Braunschweig, Germany. Using Geomagic Studio, the software from Raindrop Geomagic, Advanced Design Concepts first converted the point cloud to a polygonal model. The 3D point cloud data were brought into Geomagic Studio, software from Raindrop Geomagic of Research Triangle Park, North Carolina. Using Geomagic, ADC first converted the point cloud to a polygonal model. The next step of processing created a non-uniform rational b–spline (NURBS) model. Digitizing the Dyna Wide gas tank represented the first time that Advanced Design Concepts had used Geomagic Studio on a Harley-Davidson job. According to an expert, the company now has three people devoted to working with the program.

Design for assembly: Influencing the design process

There is extensive evidence to suggest that industrial products are being designed with an excessive number of parts and, invariably, many more costly and complex assembly operations than should be the case. A feed forward or proactive approach to the application of Design for Assembly, aimed at influencing the design process to overcome these problems, is presented. This paper reports on progress towards the development of the Design for Assembly ‘Sandpit’, where Design for Assembly procedures are integrated with advanced computer-aided design concepts to realize an assembly-oriented design environment. A case study is included to help illustrate the ways in which the approach can be used in industry.

Book Reviews : Advanced Design Concepts for Engineers, by B. S. Dhillon ; Published by Technomic Publishing Company, Inc., Lancaster, PA ©1998 ISBN 1-56676-626-5

Book Reviews : Advanced Design Concepts for Engineers, by B. S. Dhillon ; Published by Technomic Publishing Company, Inc., Lancaster, PA ©1998 ISBN 1-56676-626-5

Composite sandwich structure optimization with application to satellite components

Advanced design concepts and rigorous optimization methods are essential to address the conflicting and stringent design requirements of aerospace structures. The focus here is on the use of discrete optimization methods, specifically the genetic search method, for tailoring composite sandwich components of satellites. Failure modes induced by local instabilities associated with such composite sandwich constructions have been developed and used as design constraints in the optimization problem. A linear least-squares approximation is used in conjunction with the genetic search procedure to minimize the computational effort. Results of this study indicate that, for large-scale design optimization problems, the number of function evaluations required by this implementation is high and that more robust and alternate approximation concepts are necessary to minimize the overall computational effort.

Advanced spacecraft design for asteroid sample return mission

A new generation of M-series launch vehicle, M-V, is currently being developed at Institute of Space and Astronautical Science and the first flight is scheduled for 1996. We will carry out several planetary missions using M-V which can launch a spacecraft of a few hundred kilograms into a trans-planet orbit. Lunar penetorator mission “LUNAR-A” and Mars orbiter mission “PLANET-B” have been approved and the launch is scheduled for 1997 and 1998, respectively. Our follow-on planetary missions will be more advanced and complex because of the increasingly demanding scientific requirements. One of them is the asteroid sample return mission. In order to realize advanced planetary missions, it is absolutely necessary to establish highly advanced and light-weight spacecraft design under the constraint of launch capability. In this paper, we will describe our advanced spacecraft design concept for the asteroid sample return mission with M-V vehicle as an example.

0.1- mu m-gate, ultrathin-film CMOS devices using SIMOX substrate with 80-nm-thick buried oxide layer

A 0.1- mu m-gate CMOS/SIMOX (separation by implanted oxygen) has been successfully fabricated using high quality SIMOX substrates and an advanced design concept for the subquarter-micron region based on a simple device model. In addition, both 85-nm-gate n- and p-MOSFETs/SIMOX with 8-nm-thick silicon active layer have been realized. High parasitic resistance in the source and drain regions of the 0.1- mu m-gate CMOS/SIMOX tends to increase the propagation delay time. However, 0.1- mu m-gate CMOS/SIMOX devices with a delay time as low as 10 ps can be obtained by reducing the parasitic resistance. >

Integrity control for high temperature structural applications

High temperature composite materials in combination with advanced design and manufacturing concepts are becoming more and more important for space transportation systems like hypersonic flight and reusable reentry vehicles. In order to meet the challenging demands for thermostructural applications Carbon/Carbon and Ceramic Matrix Composites are the most promising materials with respect to weight, stiffness, strength and heat resistance. An ESA supported study has been undertaken to define an Integrity Control Methodology for thermostructural elements made from these high temperature composite materials

Development of Tube-nested Boiler Furnace for Jaggy-Fireball Combustion.

An advanced design concept of the gas-firing combustion chamber for boilers and its application to actual boiler development are presented in this paper. The concept brings about a drastic reduction of the boiler size while limiting the NOx concentration of the exhaust gas. The key is the accelerated and temperature-controlled combustion in the jaggy-fireball generated in the tube-nested combustor. The proof test of the concept was carried out using small-scale test equipment. Application to actual boilers is under way.

Design of a High-Performance Axial Compressor for Utility Gas Turbine

An aerodynamic design study to configure a high-efficiency industrial-size gas turbine compressor is presented. This study was conducted using an advanced aircraft engine compressor design system. Starting with an initial configuration based on conventional design practice, compressor design parameters were progressively optimized. To improve the efficiency potential of this design further, several advanced design concepts (such as stator ends bends and velocity controlled airfoils) were introduced. The projected poly tropic efficiency of the final advanced concept compressor design having 19 axial stages was estimated at 92.8 percent, which is 2 to 3 percent higher than the current high-efficiency aircraft turbine engine compressors. The influence of variable geometry on the flow and efficiency (at design speed) was also investigated. Operation at 77 percent design flow with inlet guide vanes and front five variable stators is predicted to increase the compressor efficiency by 6 points as compared to conventional designs having only the inlet guide vane as variable geometry.

Examining the Inherent Safety of Prism, Safr, and the Mhtgr

Three advanced design concepts, including two liquid-metal-cooled reactors (LMRs), the Power Reactor Inherently Safe Module (PRISM) and the Sodium Advanced Fast Reactor (SAFR), and a high-temperature gas-cooled reactor (HTGR) are discussed and compared. Each provides inherent or passive safety to improve system safety. The focus is on two primary objectives: reactor shutdown and shutdown heat removal. The LMR and HTGR concepts rely on inherent reactivity feedback to provide an inherent reactor response under a failure-to-scram condition; SAFR also provides a passive shutdown system using Curie point magnets (the self-actuated scram system). For shutdown heat removal, the LMR and HTGR designs rely on passive air cooling of the reactor vessel as the ultimate safety-grade system.

Structural honeycomb materials for advanced aerospace designs

With their high stiffness and low weight, honeycomb materials are becoming an increasingly important element of advanced aerospace design concepts. For example, honeycomb materials have found usage for noise damping and abradable seal applications in modern jet engines, and actively cooled honeycomb structures may be the basis of wing and fuselage design for the proposed national aerospace plane. Numerous factors influence the applicability of metallic-based honeycomb structural materials for different applications, including availability, manufacture and cost.

特集 先端接合技術と材料複合化への応用 先端接合技術と複合材料設計概念

特集 先端接合技術と材料複合化への応用 先端接合技術と複合材料設計概念

Airline Management Information System at Arkia Israeli Airlines

This paper presents an approach to developing and implementing a management information system for small airlines. The system presented is a new, comprehensive, real-time sales support and reservation system based on stateof-the-art computer technology, advanced concepts in software design, and practical experience in the travel industry. The system represents a departure from the philosophy underlying most existing airline reservation systems. It is an important strategic asset and a valuable weapon in an increasingly competitive market.

Advanced Design Concepts for Fused Quartz Pressure Transducers

The author presents the engineering design considerations applied in the development of a laboratory grade pressure standard utilising a fused quartz Bourdon tube transducer, and its adaptation to uses in field service and process control industries.

Technology for the design of high temperature rise combustors

The results of analytical and experimental studies to determine the design technology needs of high temperature rise (AT) combustors and to define candidate design concepts for meeting these needs are reviewed. These studies show that several unique design considerations and constraints apply, because a high proportion of the available airflow must be allocated to the combustion process at the high AT operating conditions. This airflow allocation is necessary to obtain efficient combustion and acceptable smoke emission levels at the high AT conditions. Important technology needs include design features to provide stable operation over very wide AT ranges and design features to minimize liner-cooling airflow requirements. Candidate design concept features for providing these needed high A J combustor capabilities are described. Included are advanced design concepts to provide combustion process staging capabilities, as well as advanced liner-cooling and structural design concepts. The current development status of these various advanced design concepts is also assessed.

Sonic fatigue of advanced composite panels in thermal environments

Combined analytic and experimental activities were performed to evaluate an advanced structural design concept for advanced composite fuselage panels suitable for V/STOL aircraft. An existing sonic fatigue analysis procedure was then evaluated. Both flat and slightly curved multibay cross-stiffened panels with graphite-epoxy skins were designed, analyzed, fabricated, and tested. The panels simulated skin-frame-stringer aircraft structure. The joints of the substructure and skin were achieved in a single-cure autoclave operation without an adhesive. The substructure consisted of graphite-epoxy hat-section stringers and glass-epoxy J-section frames. Some panels were tested in a combined acoustic-thermal environment, and others were tested in an acoustic environment at room temperature. The sonic fatigue tests were performed in a progressive wave acoustic test chamber with broadband excitation at approximately 163.5-dB overall sound pressure level. The sonic fatigue lives of the test panels exceeded the predicted lives obtained with existing semiempirical methods developed for graphite-epoxy and aluminum alloy panels featuring other design concepts and manufacturing processes.

Advanced short haul aircraft for high density markets

The short haul (less than 500 miles) passenger enplanements represent about 50% of the total domestic enplanements. These can be distinguished by the annual passenger flow for a given city pair and classified into low, medium and high density markets. NASA studies have investigated various advanced short haul aircraft concepts that have potential application in these three market areas. Although advanced operational techniques impact all market densities, advanced vehicle design concepts such as RTOL, STOL and VTOL have the largest impact in the high density markets. This paper summarizes the results of NASA sponsored high density short haul air transportation systems studies and briefly reviews NASA sponsored advanced VTOL conceptual aircraft design studies. Trends in vehicle characteristics and operational requirements will be indicated in addition to economic suitability and impact on the community.

Characterization of advanced composite materials for structural design

AbstractOur preliminary characterization of advanced composite materials has been conducted simultaneously with the development of large‐scale primary and secondary aircraft structures. We have demonstrated significant advantages over metal structure on a one‐to‐one basis. Our efficiency levels gained to date demonstrate that we have extracted about fifty percent of the maximum potential advantage. Recovery of the remaining efficiency will result from understanding material characteristics and development of advanced design concepts. We will develop and demonstrate a summary format for viewing the structural response of monolithic metals and polymers and then document the observed responses of advanced composites within the format. Our data show that the addition of high‐modulus fibers into a polymeric matrix produces a physically distinct material with substantial advantage over unreinforced polymers. The unique properties of composite materials yield a significant advantage in physical properties and in design. Full advantage of material orientation has yet to be developed in a practical design but through examples we can illustrate the potential. We develop two examples: (1) stress concentration control through buffer stripping and (2) fracture control through buffer stripping. The impact of composite material characteristics as aircraft materials and design methods is also reviewed.

The vacuum freezing vapor compression (Zarchin) process Present status and future trends

Resume The performance of the Eilat and Wrightsville Beach demonstration plants is compared to that of the Tel-Aviv pilot plant. Following various improvements, the main compressor efficiency has been brought to about 60%. At the same time, advanced design concepts tested in the Tel-Aviv pilot plant have resulted in smaller vessels and lower driving forces. When these concepts are incorporated in a commercial plant, in combination with the improved compressor, a marked reduction in water costs should result. Future development trends envisage: Multi-compressor modules, eventually made of concrete. Direct contact, evaporative feed precoolers. Multi-stage heat removal compressors, of the flexible blade type.