Design Net Engineering (United States)

In the current investigation, thermo-mechanical analysis is carried out for Hastelloy C-276 using laser beam welded butt joints. The Gaussian heat source model is used for transient thermal analysis, and the maximum temperature at the weld area resulted in residual stresses within safe limits. To validate, the experimentation was carried out with CO 2 Laser beam welding using an L 4 orthogonal array. Sample 2 had the least-residual stresses in the weldment, and the mechanical and metallurgical properties studies were carried out. The residual stress distribution was measured using X-ray diffraction and was acceptable within the yield limits of the material. Finite Element Analysis (FEA) and experimental residual stresses were compared; the FOS was 2.088, and the remaining samples were more than 2.0 compared to the base material tensile strength. Tensile tests confirmed that the strength of the weld zone is higher than that of the parent metals.

Telemedicine is an increasingly common approach to improve healthcare access in developing countries with fledgling healthcare systems. Despite the strong financial, logistical and clinical support from non-governmental organisations (NGOs), government ministries and private actors alike, the majority of telemedicine projects do not survive beyond the initial pilot phase and achieve their full potential. Based on a review of 35 entrepreneurial telemedicine and mHealth ventures, and 17 reports that analyse their operations and challenges, this article provides a narrative review of recurring failure modes, i.e. factors that lead to failure of such venture pilots. Real-world examples of successful and failed ventures are examined for key take-away messages and practical strategies for creating commercial viable telemedicine operations. A better understanding of these failure modes can inform the design of sustainable and scalable telemedicine systems that effectively address the growing healthcare disparities in developing countries.

Smart radios should play a pivotal role in addressing difficult organizational behavior issues which frustrate the migration of public safety communications toward extensive interorganizational collaboration. This paper frames how nontechnical hazards - such as mutual distrust, cultural frictions, inexperience in cooperative settings, and policy obstacles - present significant challenges to public safety cooperation. We further explain the collaborative advantage to be gained by migration toward cooperative, federated network architecture. Finally, we emphasize how smart radio technologies could facilitate trust building and control mechanisms in inter-organizational relationships, resulting over time in increased confidence in cooperation. Accordingly, we advance a perspective which bolsters the case for extending advanced military smart radio research into the development of public safety and homeland security advanced communications architectures.

We describe the design and development of the CHIPS microchannel plate detector. The Cosmic Hot Interstellar Plasma Spectrometer will study the diffuse radiation of the interstellar medium in the extreme ultraviolet band pass of 90Å to 260Å. Astronomical fluxes are expected to be low, so high efficiency in the band pass, good out-of-band rejection, low intrinsic background, and minimal image non-linearities are crucial detector properties. The detector utilizes three 75mm diameter microchannel plates (MCPs) in an abutted Z stack configuration. A NaBr photocathode material deposited on the MCP top surface enhances the quantum detection efficiency. The charge pulses from the MCPs are centroided in two dimensions by a crossed-delayline (XDL) anode. A four panel thin-film filter array is affixed above the MCPs to reduce sensitivity to airglow and scattered radiation, composed of aluminum, polyimide/boron, and zirconium filter panes. The detector is housed in a flight vacuum chamber to preserve the hygroscopic photocathode, the pressure sensitive thin-film filters, and to permit application of high voltage during ground test.

We present a status report on CHIPS, the Cosmic Hot Interstellar Plasma Spectrometer. CHIPS is the first NASA University-Class Explorer (UNEX) project. CHIPS was selected in 1998 and is now scheduled for launch in December of 2002. The grazing incidence CHIPS spectrograph will survey the sky and record spectra of diffuse emission in the comparatively unexplored wavelength band between 90 and 260 Å. These data will provide important new constraints on the temperature, ionization state, and emission measure of hot plasma in the "local bubble" of the interstellar medium.

Space-borne gravitational wave missions like LISA require Drag-Free Contorl (DFC) systems to control the motion of a constellation of spaceraft to high positional accuracy so that Michelson interferometers of vast scales can be implemented and used to detect gravitational waves. The spacecraft will continually experience forces and torques due to external disturbances, resulting in positional perturbations. Therefore the development of a DFC system is essential to stabilize the spacecraft to a specified tolerance. Prior to such space-borne gravitational wave missions, a technology demonstrator mission, such as the proposed ODIE, ELITE or SMART-2, is needed to test the feasibility of drag-free spacecraft technology. This paper discusses the requirements of the hardware needed to implement a DFC system. Contorl-loop models ahve been develoepd to model the DFC system's dynamic behavior, which enabled quantification of its performance. Results show that if an accelerometer noise level of 1×10^-12m Hz^-0.5 and thruster noise level of 1×10^-8 N Hz^-0.5 can be realized then the ODIE acceleration budget can easily be met.