157,134 research outputs found
Photovoltaic Module Encapsulation Design and Materials Selection, Volume 1, Abridged
A summary version of Volume 1, presenting the basic encapsulation systems, their purposes and requirements, and the characteristics of the most promising candidate systems and materials, as identified and evaluated by the Flat-Plate Solar Array Project is presented. In this summary version considerable detail and much supporting and experimental information has necessarily been omitted. A reader interested in references and literature citations, and in more detailed information on specific topics, should consult Reference 1, JPL Document No. 5101-177, JPL Publication 81-102, DOE/JPL-1012-60 (JPL), June 1, 1982
Multiobjective gas turbine engine controller design using genetic algorithms
This paper describes the use of multiobjective genetic algorithms (MOGAs) in the design of a multivariable control system for a gas turbine engine. The mechanisms employed to facilitate multiobjective search with the genetic algorithm are described with the aid of an example. It is shown that the MOGA confers a number of advantages over conventional multiobjective optimization methods by evolving a family of Pareto-optimal solutions rather than a single solution estimate. This allows the engineer to examine the trade-offs between the different design objectives and configurations during the course of an optimization. In addition, the paper demonstrates how the genetic algorithm can be used to search in both controller structure and parameter space thereby offering a potentially more general approach to optimization in controller design than traditional numerical methods. While the example in the paper deals with control system design, the approach described can be expected to be applicable to more general problems in the fields of computer aided design (CAD) and computer aided engineering (CAE
Soil tillage needs a radical change for sustainability
In Central Europe, the challenge in soil tillage throughout the last century can
be characterized as a fi ght against extreme climatic and economic situations.
From 1800s till the 1970s, the main requirement of soil tillage was to provide
suitable soil conditions for plant growth (moreover with fi ne structure). Both
climatic and economic diffi culties were benefi cial in establishing new tillage
trends, however overestimation of the crop demands have presumably been
promoted by the deterioration in soil quality. From the end of the 1990s, new
requirements have also been introduced because of the rise in energy prices
and because of the need to cut production costs. Th e reduced tillage in Central
European region showed some advantages, e.g. less soil disturbance and traffi c
however, that resulted in new soil condition defects (e.g. top- and subsoil
compaction, structure degradation). Th e ideas of sustainability off ered a better
solution that is to conserve soil resources and to protect the environment. A
new problem, the global climate change, and the importance of the adaptability
fasten to the original sustainable goals. In this paper the features of soil quality
deteriorating tillage (conventional, over-reduced) are summarised, the steps of
improvement are demonstrated, and factors aff ecting sustainable soil tillage are
formulated
A practical approach to goal modelling for time-constrained projects
Goal modelling is a well known rigorous method for analysing
problem rationale and developing requirements. Under the pressures typical of time-constrained projects its benefits are not accessible. This is because of the effort and time needed to create the graph and because reading the results can be difficult owing to the effects of crosscutting concerns. Here we introduce an adaptation of KAOS to meet the needs of rapid turn around and clarity. The main aim is to help the stakeholders gain an insight into the larger issues that might be overlooked if they make a premature start into implementation. The method emphasises the use of obstacles, accepts under-refined goals and has
new methods for managing crosscutting concerns and strategic decision making. It is expected to be of value to agile as well as traditional processes
Planetary Geology: Goals, Future Directions, and Recommendations
Planetary exploration has provided a torrent of discoveries and a recognition that planets are not inert objects. This expanded view has led to the notion of comparative planetology, in which the differences and similarities among planetary objects are assessed. Solar system exploration is undergoing a change from an era of reconnaissance to one of intensive exploration and focused study. Analyses of planetary surfaces are playing a key role in this transition, especially as attention is focused on such exploration goals as returned samples from Mars. To assess how the science of planetary geology can best contribute to the goals of solar system exploration, a workshop was held at Arizona State University in January 1987. The participants discussed previous accomplishments of the planetary geology program, assessed the current studies in planetary geology, and considered the requirements to meet near-term and long-term exploration goals
Editorial Special Issue on Enhancement Algorithms, Methodologies and Technology for Spectral Sensing
The paper is an editorial issue on enhancement algorithms, methodologies and technology for spectral sensing and serves as a valuable and useful reference for researchers and technologists interested in the evolving state-of-the-art and/or the emerging science and technology base associated with spectral-based sensing and monitoring problem. This issue is particularly relevant to those seeking new and improved solutions for detecting chemical, biological, radiological and explosive threats on the land, sea, and in the air
Application of computational physics within Northrop
An overview of Northrop programs in computational physics is presented. These programs depend on access to today's supercomputers, such as the Numerical Aerodynamical Simulator (NAS), and future growth on the continuing evolution of computational engines. Descriptions here are concentrated on the following areas: computational fluid dynamics (CFD), computational electromagnetics (CEM), computer architectures, and expert systems. Current efforts and future directions in these areas are presented. The impact of advances in the CFD area is described, and parallels are drawn to analagous developments in CEM. The relationship between advances in these areas and the development of advances (parallel) architectures and expert systems is also presented
e-Report Generator Supporting Communications and Fieldwork: A Practical Case of Electrical Network Expansion Projects
In this piece of work we present a simple way to incorporate Geographical Information System tools that have been developed using open source software in order to help the different processes in the expansion of the electrical network. This is accomplished by developing a novel fieldwork tool that provides the user with automatically generated enriched e-reports that include information about every one of the involved private real estates in a specific project. These reports are an eco-friendly alternative to paper format, and can be accessed by clients using any kind of personal device with a minimal set of technical requirements
Space Transportation Materials and Structures Technology Workshop. Volume 1: Executive summary
The workshop was held to provide a forum for communication within the space materials and structures technology developer and user communities. Workshop participants were organized into a Vehicle Technology Requirements session and three working panels: Materials and Structures Technologies for Vehicle Systems; Propulsion Systems; and Entry Systems. The goals accomplished were (1) to develop important strategic planning information necessary to transition materials and structures technologies from lab research programs into robust and affordable operational systems; (2) to provide a forum for the exchange of information and ideas between technology developers and users; and (3) to provide senior NASA management with a review of current space transportation programs, related subjects, and specific technology needs. The workshop thus provided a foundation on which a NASA and industry effort to address space transportation materials and structures technologies can grow
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