Between September 18th and October 13th, 2012, National Institute for Occupational Safety and Health (NIOSH) researchers and the Silica/Milling-Machines Partnership coordinated by the National Asphalt Pavement Association (NAPA) conducted field testing of a local exhaust ventilation system (LEV) on a Roadtec RX600e cold milling machine. The tests included ten days of air sampling across seven different highway construction sites in Indiana. At each site, full-shift personal breathing zone samples for respirable crystalline silica were collected from the operator and ground man during the course of normal employee work activities of asphalt pavement milling.

关键词：大气；室外大气；空气污染

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Weapons release at supersonic speeds from an internal weapons bay is a highly desirable capability. To ensure a successful release at multiple Mach numbers, the aerodynamic environment must be well-understood and repeatable, with a robust system for safe testing of store separation. For this reason, experimental methods were used to investigate the characteristics of a scaled WICS bay with a length-to-depth ratio of 4.5 at multiple Mach numbers and stagnation pressures. Three new nozzles were designed, manufactured, and characterized for the AFIT small supersonic tunnel, yielding freestream Mach numbers of 2.22, 1.84, and 1.43. In addition, a control valve was recon gured to achieve stagnation pressures as low as 1.0 psia. These nozzles were then used in conjunction with piezosresistive pressure transducers and high-speed Schlieren photography to capture the time-varying pressure signal and spectra of the cavity. Resonant frequencies from these tests matched very well with analytically predicted results for the Mach 2.3 and Mach 1.9 nozzles. The Mach 1.5 nozzle posed some di culties for the con guration tested due to shocks re ecting into the cavity. The Mach 2.3 nozzle was utilized in freedrop testing of a 1:20 scaled sphere and compared to computational simulations. The computational solution was obtained using the OVERFLOW solver with incorporated 6DOF motion and the DDES/SST hybrid turbulence model. Analysis of the Schlieren video generated by the experimental tests allowed direct comparison of computational and experimental trajectories. Measured trajectories compared closely to computational trajectories, especially for the lowest stagnation pressure settings, where heavy Mach scaling yielded operationally relevant results, despite the small scale of the tests.

关键词：压力传感器；谐振频率；罗斯特模式

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Transport development bring a negative impact on human survival ecological environment, such as destruction of vegetation, air pollution, soil erosion and other environmental issues.The actuality proves that the use of tunnel development of underground space can improve traffic quality, while also protecting the environment.Therefore, tunnel engineering and utilization of undergrotmd space are to protect the ecological environment to be effective ways for realizing economic sustainable development of economy.In this paper, based on the practical application at home and abroad, for the big cities, mountain areas, river waters, the suitability evaluation and beneficial discussion about the transportation by using tunnel to protect the ecological environment are of great practical significance to protect and improve the ecological environment.

关键词：大气；生态环境；空气治理

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According to the NRC and the USGCRP, changes in the earth's climate--including higher temperatures, changes in precipitation, rising sea levels, and increases in the severity and frequency of severe weather events--are under way and expected to grow more severe over time. These impacts present significant risks to the nation's energy infrastructure. Economic losses arising from weather-related events--including floods, droughts, and storms--have been large and are increasing, according to USGCRP. Adaptation--an adjustment to natural or human systems in response to actual or expected climate change--is a risk-management strategy to help protect vulnerable sectors and communities that might be affected by climate change. GAO was asked to examine the vulnerability of the nation's energy infrastructure to climate change impacts. This report examines: (1) what is known about potential impacts of climate change on U.S. energy infrastructure; (2) measures that can reduce climate-related risks and adapt energy infrastructure to climate change; and (3) the role of the federal government in adapting energy infrastructure and adaptation steps selected federal entities have taken. GAO reviewed climate change assessments; analyzed relevant studies and agency documents; and interviewed federal agency officials and industry stakeholders, including energy companies at four sites that have implemented adaptive measures.

关键词：气候变化；适应；干旱；能源；控制器

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One-dimensional transient heat transfer analysis is frequently used to provide quick estimates of the performance of thermal protection system concepts for reentry systems. While finite difference techniques are commonly employed when solving simple single-material thermal problems, more complex cases with multiple layers can complicate the numerical implementation. A control volume analysis is used in the present work to derive a finite volume approach to the 1-D thermal analysis problem using generalized coordinates. Details of the numerical implementation are also discussed to highlight how this technique can simplify the overall solution process. Finally, two example problems are used to validate the accuracy of the approach, one of which involves analysis of a multilayer TPS problem with non-uniform grid spacing.

关键词：传热；热分析；复合材料；有限元法

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Electromechanica Inc. was tasked with researching and developing a proof of concept robot tool for in-situ pipe inspection of fleet piping. Electromechanica has designed and fabricated a proof of concept robot tool based on a pneumatically actuated peristaltic motion. This motion is accomplished by the use of inflatable pneumatic grippers, as well as a novel flexible pneumatic cylinder capable of actuation in a variety of articulated positions. Various representative piping systems were used to successfully test locomotion and guidance of the system.

关键词：管道；机器人；计算机程序；发动机气缸

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A complement to the development of new fuels to meet future energy demands of the U.S. Navy is the enhancement of energy density of existing fuels, thus increasing system payloads, ranges, and/or performance. Addition of energetic solid phase materials, such as boron, magnesium, or aluminum, to liquid hydrocarbon-based fuels can potentially increase energy density. Previous studies investigating the effect of energetic metal addition to liquid hydrocarbon-based fuels have produced mixed results. Boron has excellent potential as a liquid fuel additive due to its high volumetric and gravimetric heating value. Boron carbide (B4C) is widely available due to its commercial application as an abrasive. Boron particles were first tested as fuel additives in the 1950s to 1970s during rocket development and found to significantly increase fuel energy density but boron slurry combustion has problems with ignition, flame stability, and burnout. Recent advances in nanotechnology may allow for high-volume production of boron nanoparticles coated with catalysts and organics to enhance and control combustion, promote suspension and dispersion in fuel, and inhibit premature oxidation. Controlled studies on the effect of boron nanoparticle addition on fuel aerosol droplet size during group burning experiments were conducted by the U.S. Naval Research Laboratory (NRL Code 6114) and the Hawaii Natural Energy Institute (HNEI) at the University of Hawaii (UH) from 2009 to 2011. These studies were performed using a benchtop fuel burner assembly system with a Phase-Doppler-Particle Analyzer (PDPA) to investigate the effect of specific nanoparticle addition (boron, CeO2-coated boron, and CeO2) on aerosol droplet size and velocity in a JP-5 carrier fuel. Results of this study showed little to no effect of boron nanoparticle addition (approximately 2.5% weight loading) on aerosol droplet size and velocity distribution fields in the wet, or no flame, condition. Results did suggest an effect of boron nanoparticle addition in the flame case. Rate of change in average droplet diameter with distance from the flame base was greater in the presence of boron nanoparticles, suggesting enhanced combustion and increased droplet evaporation in the JP-5 carrier fuel. Additionally, there was a measureable increase in average droplet velocity near the flame base. However, the opposite effect was seen when reduced CeO2 was used as a catalysts or catalyst only was added to JP-5, suggesting combustion was inhibited.

关键词：硼；燃烧速度；燃烧；能量性质

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In probabilistic design of materials for fracture-critical components in modern military turbine engines, a typical maximum design target risk (DTR) is 5 x 10 to the minus 8th power component failures/engine flight hour. This metric underscores the essential role of safety in a design process that simultaneously strives to achieve performance, efficiency, reliability, and affordability throughout the life cycle of the engine. Traditionally, the design and life management approaches for engine materials have typically relied on extensive testing programs to produce large databases of fatigue data, from which statistically based life limits are derived by extrapolation from the mean fatigue behavior. However, we have found that the statistical behavior of fatigue lifetimes under a given test condition often exhibits a bimodal form, and that the trends in mean vs. minimum fatigue lifetime typically respond differently to loading or to microstructural variables. Under such circumstances, the underlying life-limiting mechanisms appear to exhibit a probabilistic microstructural hierarchy in fatigue resistance that is controlled by susceptibility of local microstructural neighborhoods to early damage and the growth of small cracks. These findings suggest that significant opportunities may exist for reductions in uncertainty in materials life-cycle prediction and management, if such hierarchies can be understood and controlled. This paper explores the potential implications of these findings, and a number of possible approaches are suggested for incorporating the insights of life-limiting fatigue into methods of integrated computational materials engineering (ICME) to support optimized life-cycle design of materials and components in turbine engines.

关键词：合金；损伤容限；双模式；效率；疲劳设计

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Owing to the favorable ambiguity function properties and the increased deployment, mobile communications systems are useful for passive bistatic radar applications. Further, simultaneously using multiple illuminators in a multistatic configuration will improve the radar performance, providing spatial diversity and increased resolution. We compute modified Cram r-Rao lower bounds (MCRLB) for the target parameter (delay, Doppler) estimation error using universal mobile telecommunications system (UMTS) signals as illuminators of opportunity for passive multistatic radar systems. We consider both coherent and non-coherent processing modes. These expressions for MCRLB are an important performance metric in that they enable the selection of the optimal illuminators for estimation.

关键词：双基地雷达；天线波瓣；多普勒系统

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This project is a follow-up to Florida Department of Transportation (FDOT) research project BD545-61, Impact of Lane Closures on Roadway Capacity (specifically, Part A: Development of a Two-Lane Work Zone Lane Closure Analysis Procedure and Part C: Modeling Diversion Propensity at Work Zones). In this previous project, the primary objective was to update the procedure in the Plans Preparation Manual (PPM), Volume 1, Section 10.14.7 (2006), for two-lane roadways. Field data collection was not included in the previous project; thus, the results were based strictly on simulation data from the FlagSim simulation program. The primary objective of this project was to update the two-lane roadway with a lane closure analysis procedure developed under the previous project, based on calibrating the FlagSim simulation program to field data. An additional aspect of this that was not considered in the BD545-61 project was to account for the effect of grade on the work zone performance measures. An additional project objective was to update the RTF estimation method developed under the BD545-61 project, as necessary, based on measured traffic demands (before and during) at work zone field sites. Field data were collected at three sites and used to calibrate the FlagSim program.

关键词：封闭行车线；工作区；交通能力

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