11,672 research outputs found

    Methodology for an integrated modelling of macro and microscopic processes in urban transport demand

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    The paper presents the theoretical formulation and the underlying assumptions for an activity-based approach of transport demand modelling. Starting with the definition of a time hierarchy of decision-making in the urban environment, rules are formulated that dictate the general hierarchic structure of individuals’ choices in the urban system. The temporal scale defines decisions for activities and their daily sequence, the geographical scale decisions associated to destination choice processes. We build activity plans (number and daily sequence of activities) from an empirical data set and calculate trip paths (time-spatial trajectories including transport modes and travel destinations) assuming consumers to maximize their utility in the decision-making process. First results of the translation of the theoretical model into a real-world application are shown for the city of Santiago, Chile

    Meeting IMT 2030 Performance Targets: The Potential of OTFDM Waveform and Structural MIMO Technologies

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    The white paper focuses on several candidate technologies that could play a crucial role in the development of 6G systems. Two of the key technologies explored in detail are Orthogonal Time Frequency Division Multiplexing (OTFDM) waveform and Structural MIMO (S-MIMO)

    Ancient and historical systems

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    The next 25 years: Industrialization of space: Rationale for planning

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    The goals of NASA's space industralization program include contributing to increased productivity on earth without taxing the environment, generating new values through extraterrestrial productivity, and providing new growth options for the future which include the permanent settlement of space and long-range colonization and exploration projects. In planning the long-range space program based on essentially utilitarian aspects, without losing sight of the more humanistically significant long term, and to forecast associated technology requirements, a realistic approach is obtained by combining extrapolative and normative planning modes so that common stepping stones can be identified. In the extrapolative view, alternative futures are projected on the basis of past and current trends and tendencies. In the normative view, some ideal state in the far future is envisioned or postulated, and policies and decisions are directed toward its attainment

    Technology for large space systems: A special bibliography with indexes (supplement 04)

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    This bibliography lists 259 reports, articles, and other documents introduced into the NASA scientific and technical information system between July 1, 1980 and December 31, 1980. Its purpose is to provide information to the researcher, manager, and designer in technology development and mission design in the area of the Large Space Systems Technology Program. Subject matter is grouped according to systems, interactive analysis and design. Structural concepts, control systems, electronics, advanced materials, assembly concepts, propulsion, solar power satellite systems, and flight experiments

    Comparison Between Programming Languages Prolog , C ++ , Pascal

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    The temporal evolution and expansion of the areas of the use of electronic computers has increased in the accumulation of knowledge and the size of the symbols used until later formed the so-called programming languages "Programming Language" and is characterized by programming languages in fact instructed composed of sentences, not symbols grouped only, in addition to the fact that these sentences are very close to the sentences used in normal conversational languages. I have many number of these languages to expand coding on the one hand, and the different areas of use systems, computer has made studies in more than one center of electronic computing centers around the possibility of the development of languages commensurate with the area where he works, and here began the logic in multiple programming languages and expansion has been published in the last twenty years, a large number of languages that are designed on the principles of different codes, which popularized the use of the department of comprehensiveness and accuracy and has become used on a global level, and which disappeared or remained section used on a small scale and within limited areas. It is the most important languages that has spread on a global level language Fortran and Pascal and Fortran language Gobol language C ++.Data Processin

    NASA SBIR abstracts of 1991 phase 1 projects

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    The objectives of 301 projects placed under contract by the Small Business Innovation Research (SBIR) program of the National Aeronautics and Space Administration (NASA) are described. These projects were selected competitively from among proposals submitted to NASA in response to the 1991 SBIR Program Solicitation. The basic document consists of edited, non-proprietary abstracts of the winning proposals submitted by small businesses. The abstracts are presented under the 15 technical topics within which Phase 1 proposals were solicited. Each project was assigned a sequential identifying number from 001 to 301, in order of its appearance in the body of the report. Appendixes to provide additional information about the SBIR program and permit cross-reference of the 1991 Phase 1 projects by company name, location by state, principal investigator, NASA Field Center responsible for management of each project, and NASA contract number are included

    Small business innovation research. Abstracts of completed 1987 phase 1 projects

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    Non-proprietary summaries of Phase 1 Small Business Innovation Research (SBIR) projects supported by NASA in the 1987 program year are given. Work in the areas of aeronautical propulsion, aerodynamics, acoustics, aircraft systems, materials and structures, teleoperators and robotics, computer sciences, information systems, spacecraft systems, spacecraft power supplies, spacecraft propulsion, bioastronautics, satellite communication, and space processing are covered
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