New data on painite

A crystal of painite discovered in 1979 in a parcel of rough gem spinel from Burma represents the third known crystal of the species. This crystal is similar to the type crystal in most respects. Chemical analyses of both the new crystal and the type crystal confirmed the essential constituents reported by Moore and Araki (1976) and showed in addition the presence of trace amounts of Fe, Cr, V, Ti, Na, and Hf. Optical absorption spectra suggest that the red colour of painite is caused principally by Cr^(3+) and V^(3+)

Tribodynamics of hydraulic actuated clutch system for engine-downsizing in heavy duty off-highway vehicles

Engine downsizing is desired for modern heavy-duty vehicles to enhance fuel economy and reduce emissions. However, the smaller engines usually cannot overcome the parasitic loads during engine start-up. A new clutch system is designed to disconnect the downsized engine from the parasitic losses prior to the idling speed. A multi-scale, multi-physics model is developed to study the clutch system. Multi-body dynamics is used to study the combined translational–rotational motions of the clutch components. A micro-scale contact model is incorporated to represent the frictional characteristics of the sliding surfaces. Although the clutch is designed for dry contact operation, leakage of actuating hydraulic fluid can affect the interfacial frictional characteristics. These are integrated into the multi-body dynamic analysis through tribometric studies of partially wetted surfaces using fresh and shear-degraded lubricants. Multi-scale simulations include sensitivity analysis of key operating parameters, such as contact pressure. This multi-physics approach is not hitherto reported in the literature. The study shows the importance of adhesion in dry clutch engagement, enabling full torque capacity. The same is also noted for any leakage of significantly shear-degraded lubricant into the clutch interfaces. However, the ingression of fresh lubricant into the contact is found to reduce the clutch torque capacity

Upper Stage Engine Composite Nozzle Extensions

Carbon-carbon (C-C) composite nozzle extensions are of interest for use on a variety of launch vehicle upper stage engines and in-space propulsion systems. The C-C nozzle extension technology and test capabilities being developed are intended to support National Aeronautics and Space Administration (NASA) and United States Air Force (USAF) requirements, as well as broader industry needs. Recent and on-going efforts at the Marshall Space Flight Center (MSFC) are aimed at both (a) further developing the technology and databases for nozzle extensions fabricated from specific CC materials, and (b) developing and demonstrating low-cost capabilities for testing composite nozzle extensions. At present, materials development work is concentrating on developing a database for lyocell-based C-C that can be used for upper stage engine nozzle extension design, modeling, and analysis efforts. Lyocell-based C-C behaves in a manner similar to rayon-based CC, but does not have the environmental issues associated with the use of rayon. Future work will also further investigate technology and database gaps and needs for more-established polyacrylonitrile- (PAN-) based C-C's. As a low-cost means of being able to rapidly test and screen nozzle extension materials and structures, MSFC has recently established and demonstrated a test rig at MSFC's Test Stand (TS) 115 for testing subscale nozzle extensions with 3.5-inch inside diameters at the attachment plane. Test durations of up to 120 seconds have been demonstrated using oxygen/hydrogen propellants. Other propellant combinations, including the use of hydrocarbon fuels, can be used if desired. Another test capability being developed will allow the testing of larger nozzle extensions (13.5- inch inside diameters at the attachment plane) in environments more similar to those of actual oxygen/hydrogen upper stage engines. Two C-C nozzle extensions (one lyocell-based, one PAN-based) have been fabricated for testing with the larger-scale facility

RSLES: an architectural implementation of a decision support system for optimal recruit station location

This thesis describes a component-based methodology for developing a decision support system (DSS) for optimal location of military recruiting stations in regional recruiting markets. The DSS is designed to ensure that stations are selected that minimize cost for a given level of production. The interface allows users to perform "what if' analysis to determine if there are better locations to meet desired objectives. The Recruit Station Location Evaluation System (RSLES) integrates a user interface, a database, a GAMS optimizer model and a geographic information system (GIS) mapping engine to provide a flexible environment that leverages operational recruiting, market analysis, and demographic information for decision-makinghttp://www.archive.org/details/rslesarchitectur00houcMajor, United States Marine CorpsApproved for public release; distribution is unlimited

Perencanaan Teknik Mesin.

Buku ini ditulis untuk mahasiswa teknik yang mengikuti kuliah dalam pelajaran perencanaan teknik mesin. Mahasiswa seperti itu akan memerlukan serangkaian sarana teknik yang terutama terdiri dari matematika bahasa komputer dan kemampuan dalam menggunakan bahasa (Inggris) untuk mengutarakan sesuatu dalam bentuk lisan maupun tulisan.xix + 518 hlm; 16 x 23 Cm