Characterization of silicon dioxide for a capacitance-type meteoroid penetration detector

Fabrication and testing of large area metal oxide silicon capacitors for micrometeoroid counting in spac

Development of single cell protectors for sealed silver-zinc cells, phase 1

A single cell protector (SCP) assembly capable of protecting a single silver-zinc (Ag Zn) battery cell was designed, fabricated, and tested. The SCP provides cell-level protection against overcharge and overdischarge by a bypass circuit. The bypass circuit consists of a magnetic-latching relay that is controlled by the high and low-voltage limit comparators. Although designed specifically for secondary Ag-Zn cells, the SCP is flexible enough to be adapted to other rechargeable cells. Eighteen SCPs were used in life testing of an 18-cell battery. The cells were sealed Ag-Zn system with inorganic separators. For comparison, another 18-cell battery was subjected to identical life test conditions, but with battery-level protection rather than cell-level. An alternative approach to the SCP design in the form of a microprocessor-based system was conceptually designed. The comparison of SCP and microprocessor approaches is also presented and a preferred approach for Ag-Zn battery protection is discussed

Space station propulsion analysis study

This paper summarizes the impacts on the weight, volume and power usage of a manned space station and its 90-day resupply for three integrated, auxiliary propulsion subsystems. The study was performed in coordination with activities of the Space Staton Concept Development Group (CDG). The study focused on three space station propulsion high-low thrust options that make use of fluids that will be available on the manned space station. Specific uses of carbon dioxide, water and cryogen boiloff were considered. For each of the options the increase in station hardware mass and volume to accommodate the dual thrust option is offset by the resupply savings, relative to the reference hydrazine system, after one to several resupplies. Over the life of the station the savings in cost of logistics could be substantial. The three options are examples of alternative technology paths that, because of the opportunity they provide for integration with the environmental control life support system (ECLSS) and OTV propellant storage systems, may reduce the scarring which is required on the early station to meet the increasing propulsion requirements of the growth station

Evaluation of Background Subtraction Algorithms with Post-processing

Processing a video stream to segment foreground objects from the background is a critical first step in many computer vision applications. Background subtraction (BGS) is a commonly used technique for achieving this segmentation. The popularity of BGS largely comes from its computational efficiency, which allows applications such as humancomputer interaction, video surveillance, and traffic monitoring to meet their real-time goals. Numerous BGS algorithms and a number of postprocessing techniques that aim to improve the results of these algorithms have been proposed. In this paper, we evaluate several popular, state-of-the-art BGS algorithms and examine how post-processing techniques affect their performance. Our experimental results demonstrate that post-processing techniques can significantly improve the foreground segmentation masks produced by a BGS algorithm. We provide recommendations for achieving robust foreground segmentation based on the lessons learned performing this comparative study. 1

Editorial: Towards leaner and more effective value chain development

Value chain development (VCD) is a common term in today’s development lexicon1, where its use tends to conjure passionate ideas about how development programming can support smallholder participation in growing markets in the interest of economic growth, job creation, gender empowerment, and sustainable use of natural resources, among other goals. Since the early 2000s, Enterprise Development and Microfinance (EDM) has featured considerable debate on how to design market-oriented development interventions with smallholders, often based on positive experiences by a given NGO or project in a particular context. Early articles helped to put VCD on the development agenda, while advancing innovation in market-based project design and implementation. However, after more than a decade of it being firmly placed on the agenda, we still know relatively little about VCD. Apart from isolated case studies, the question of whether VCD has lived up to the expectations of smallholders, of the private sector, and of development agencies remains an open one. This double edition of EDM addresses the design, implementation, and impact of VCD support to smallholders and to small and medium enterprises (SMEs) as an important, yet under-researched dimension of VCD. The eight articles look into the needs and opportunities for increasing the effectiveness of VCD support services, with discussions on: the role of NGOs or governments in VCD; how large-scale buyers and certification programs shape VCD; and the role of finance and impact bonds in VCD. Advancing ideas on how to get the right mix of services, at the right time, to the right people, taking into account variations in the context in which livelihoods and business activities are embedded, will help stakeholders to effectively deliver on poverty and broader development goals

Development of single-cell protectors for sealed silver-zinc cells

Three design approaches to cell-level protection were developed, fabricated, and tested. These systems are referred to as the single-cell protector (SCP), multiplexed-cell protector(MCP). To evaluate the systems 18-cell battery packs without cell level control were subjected to cycle life test. A total of five batteries were subjected to simulate synchronous orbit cycling at 40% depth of discharge at 22C. Batteries without cell-level protection failed between 345 and 255 cycles. Cell failure in the cell level protected batteries occurred between 412 and 540. It was determined that the cell-level monitoring and protection is necessary to attain the long cycle life of a AgZn battery. The best method of providing control and protection of the AgZn cells depends on the specific application and capability of the user