An advanced technology space station for the year 2025, study and concepts

A survey was made of potential space station missions that might exist in the 2020 to 2030 time period. Also, a brief study of the current state-of-the-art of the major subsystems was undertaken, and trends in technologies that could impact the subsystems were reviewed. The results of the survey and study were then used to arrive at a conceptual design of a space station for the year 2025. Factors addressed in the conceptual design included requirements for artificial gravity, synergies between subsystems, and the use of robotics. Suggestions are made relative to more in-depth studies concerning the conceptual design and alternative configurations

Space power distribution system technology. Volume 1: Reference EPS design

The multihundred kilowatt electrical power aspects of a mannable space platform in low Earth orbit is analyzed from a cost and technology viewpoint. At the projected orbital altitudes, Shuttle launch and servicing are technically and economically viable. Power generation is specified as photovoltaic consistent with projected planning. The cost models and trades are based upon a zero interest rate (the government taxes concurrently as required), constant dollars (1980), and costs derived in the first half of 1980. Space platform utilization of up to 30 years is evaluated to fully understand the impact of resupply and replacement as satellite missions are extended. Such lifetimes are potentially realizable with Shuttle servicing capability and are economically desirable

Practical extensions to the level of repair analysis

The level of repair analysis (lora) gives answers to three questions that are posed when deciding on how to maintain capital goods: 1) which components to repair upon failure and which to discard, 2) at which locations in the repair network to perform each type of repairs, and 3) at which locations in the network to deploy resources, such as test equipment. The goal is to achieve the lowest possible life cycle costs. Various models exist for the lora problem. However, these models tend to be restrictive in that specic business situations cannot be incorporated, for example, having repair equipment with a capacity restriction or the occurrence of unsuccessful repairs.We discuss and model various practically relevant extensions to an existing minimum cost \ud ow formulation for the lora problem. We show the added value of these model renements in an extensive numerical experiment

Requirements for the conceptual design of advanced underground coal extraction systems

Conceptual design requirements are presented for underground coal mining systems having substantially improved performance in the areas of production cost and miner safety. Mandatory performance levels are also set for miner health, environmental impact, and coal recovery. In addition to mandatory design goals and constraints, a number of desirable system characteristics are identified which must be assessed in terms of their impact on production cost and their compatibility with other system elements. Although developed for the flat lying, moderately thick seams of Central Appalachia, these requirements are designed to be easily adaptable to other coals

Stochastic capital depreciation and the comovement of hours and productivity

An unresolved question concerning stochastic depreciation shocks is whether they have to be unrealistically large to have any useful role in a dynamic general equilibrium model economy, as Ambler and Paquet (1994) first suggested. We first consider implied depreciation rates from sectoral data from the Bureau of Economic Analysis. These depreciation rates vary across time solely due to compositional changes within each sector. Hence, they tend to understate the range of fluctuation that would hold if the economic shelf life of capital varied endogenously as in Cooley, Greenwood and Yorukoglu (1997). We find, however, that if depreciation rates follow a Markov switching process, a low variance of the depreciation rate can generate the low correlation between hours worked and productivity in a simple model economy. White noise and autoregressive depreciation shocks, in contrast, require a counterfactually large variance in the depreciation rate to reduce the hours-productivity correlation. We also illustrate the level effects implied by nonlinear decision rules in simulations of dynamic general equilibrium models that include Markov switching parameters. Linear decision rules, in contrast, imply certainty equivalence and ignore the aversion that agents have to the skewed shock distributions that characterize Markov switching.Econometric models ; Productivity

Space biology initiative program definition review. Trade study 6: Space Station Freedom/spacelab modules compatibility

The differences in rack requirements for Spacelab, the Shuttle Orbiter, and the United States (U.S.) laboratory module, European Space Agency (ESA) Columbus module, and the Japanese Experiment Module (JEM) of Space Station Freedom are identified. The feasibility of designing standardized mechanical, structural, electrical, data, video, thermal, and fluid interfaces to allow space flight hardware designed for use in the U.S. laboratory module to be used in other locations is assessed

Methods of Technical Prognostics Applicable to Embedded Systems

Hlavní cílem dizertace je poskytnutí uceleného pohledu na problematiku technické prognostiky, která nachází uplatnění v tzv. prediktivní údržbě založené na trvalém monitorování zařízení a odhadu úrovně degradace systému či jeho zbývající životnosti a to zejména v oblasti komplexních zařízení a strojů. V současnosti je technická diagnostika poměrně dobře zmapovaná a reálně nasazená na rozdíl od technické prognostiky, která je stále rozvíjejícím se oborem, který ovšem postrádá větší množství reálných aplikaci a navíc ne všechny metody jsou dostatečně přesné a aplikovatelné pro embedded systémy. Dizertační práce přináší přehled základních metod použitelných pro účely predikce zbývající užitné životnosti, jsou zde popsány metriky pomocí, kterých je možné jednotlivé přístupy porovnávat ať už z pohledu přesnosti, ale také i z pohledu výpočetní náročnosti. Jedno z dizertačních jader tvoří doporučení a postup pro výběr vhodné prognostické metody s ohledem na prognostická kritéria. Dalším dizertačním jádrem je představení tzv. částicového filtrovaní (particle filtering) vhodné pro model-based prognostiku s ověřením jejich implementace a porovnáním. Hlavní dizertační jádro reprezentuje případovou studii pro velmi aktuální téma prognostiky Li-Ion baterii s ohledem na trvalé monitorování. Případová studie demonstruje proces prognostiky založené na modelu a srovnává možné přístupy jednak pro odhad doby před vybitím baterie, ale také sleduje možné vlivy na degradaci baterie. Součástí práce je základní ověření modelu Li-Ion baterie a návrh prognostického procesu.The main aim of the thesis is to provide a comprehensive overview of technical prognosis, which is applied in the condition based maintenance, based on continuous device monitoring and remaining useful life estimation, especially in the field of complex equipment and machinery. Nowadays technical prognosis is still evolving discipline with limited number of real applications and is not so well developed as technical diagnostics, which is fairly well mapped and deployed in real systems. Thesis provides an overview of basic methods applicable for prediction of remaining useful life, metrics, which can help to compare the different approaches both in terms of accuracy and in terms of computational/deployment cost. One of the research cores consists of recommendations and guide for selecting the appropriate forecasting method with regard to the prognostic criteria. Second thesis research core provides description and applicability of particle filtering framework suitable for model-based forecasting. Verification of their implementation and comparison is provided. The main research topic of the thesis provides a case study for a very actual Li-Ion battery health monitoring and prognostics with respect to continuous monitoring. The case study demonstrates the prognostic process based on the model and compares the possible approaches for estimating both the runtime and capacity fade. Proposed methodology is verified on real measured data.

Diagnostic Applications for Micro-Synchrophasor Measurements

This report articulates and justifies the preliminary selection of diagnostic applications for data from micro-synchrophasors (µPMUs) in electric power distribution systems that will be further studied and developed within the scope of the three-year ARPA-e award titled Micro-synchrophasors for Distribution Systems

Prospects to Use Biogas of Refuse Dams of Dnipropetrovsk Region (Ukraine) as Alternative Energy Carrier

Prospects for recovery and use of biogas from solid domestic waste landfills in Dnipropetrovsk region have been considered. Scientific sources have been analyzed. The world practices to use biogas from solid domestic waste landfills have been estimated. Gas volume released has been studied. Methane released by solid domestic waste landfills may be used effectively as automobile fuel, electric powers and heat depending upon location of the landfills as for business infrastructure. Methane utilization will make it possible to solve a problem of improving the safety of solid domestic waste landfills in terms of environment. Scientific substantiation of technological solutions concerning recovery of methane from solid domestic waste landfills is impossible without involving dependences which determine total volume of landfill gas being released. That will help perform feasibility evaluation as for projects to use landfill gas. Practical proposals concerning the selection and substantiation of priorities to use methane released by solid domestic waste landfills have been made. In particular, operation schedule for specific conditions of Ihren landfill located in Dnipropetrovsk region has been proposed