A high-load endurance test was performed on the tail drivetrain of an H-60 Blackhawk helicopter to determine the resistance to gear tooth fracture under power levels exceeding the maximum continuous rating. During posttest inspection, it was found that a tooth had broken off of the tail takeoff spiral bevel gear. In addition, a moderate spall was found on the outer race of the intermediate gearbox input gear shaft support bearing. There were no obvious indications of the gear tooth failure during the duration of the test, making the determination of the time of tooth fracture critical to understanding the resistance of the H-60 tail drivetrain to overloads. This report analyzes vibration data sampled periodically throughout the test to determine the initiation time of these two specific mechanical failures. Both faults occurred naturally in a system environment, making the dataset of particular interest. Several existing gear and bearing vibration analysis techniques were utilized. These methods clearly identified the time of initiation of both the spiral bevel gear tooth fracture and the bearing spall. The capability of the different analysis methods relative to predicting gear tooth crack and bearing spall initiation are compared.

关键词：轴承；诊断设备；故障（力学）；故障诊断

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针对车辆上同时应用排气制动与涡轮增压的情况,研究了排气制动对增压器轴向载荷的影响。通过排气制动与增压器联动试验测量了增压器在各个工况下的轴向载荷,从而确定了数值计算所需的边界条件,并通过数值计算获取了增压器在各个工况的轴向载荷的分布情况。结果表明,与正常工况相比,增压器在排气制动工况下其轴向载荷显著增大,且排气背压越高,增压器轴向载荷越大;涡轮级轴向载荷反向且增大;压气机级轴向载荷显著下降,但方向不变。

关键词：增压器；排气制动；轴向载荷；联动试验

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A study of the behavior and evaluation of the Ant Colony Optimization algorithm (ACO) in Type-1 and Type-2 Fuzzy Controller design is presented in this chapter. The main objective of the work is based on the main reasons in tuning membership functions for the optimization Fuzzy Controllers of the benchmark problem known as the Water Tank with the algorithm of Ant Colony Optimization. For the design of Type-1 and Type-2 Fuzzy Controllers for particular applications, the use of bio-inspired optimization methods have helped in the complex task of finding the appropriate values of the parameters and the structure of fuzzy systems. In this research we consider the application of ACO as the paradigm that aids in the optimal design of Type-1 and Type-2 Fuzzy Controllers. We also analyzed that in evaluating the uncertainty, the results in the simulation are better with Type-2 Fuzzy Controllers. Finally, provide a comparison of the different methods for the case of designing Type-1 and Type-2 Fuzzy Controllers with Ant Colony Optimization.

关键词：蚁群优化算法；模糊控制器；仿真

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采用理论计算、数值仿真和实验相结合的方法探讨了材料、有无芯轴、芯头个数和芯棒伸出量对汽车防护杠用不锈钢管绕弯成形质量的影响。结果表明:相同工艺条件下,不锈钢SUS304管材比碳素钢Q235A更易产生截面畸变,但外侧壁厚减薄率较小;材料相同时,有芯轴支撑管材切向压应力和拉应力最大值的差值较小,材料流动更加均匀,能很好地抑制管材的截面畸变和失稳起皱;芯头个数是影响截面变形的最重要因素,芯头个数为3时,截面畸变率最小,其最大值仅为4.2%;芯棒伸出量过小,管材内侧容易起皱,截面畸变率较大;而伸出量过大时,管材外侧壁厚减薄严重,甚至导致拉裂;芯棒伸出量为9mm时,管材的弯曲成形质量最好。仿真结果与理论解析解和实测值吻合较好。

关键词：汽车防护杠；大口径薄壁管；绕弯成形；工艺参数；数值仿真

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基于Atkinson理论循环建立混合动力汽油机的性能仿真模型,确定出合适的压缩比与配气正时。分别采用增加活塞顶面凸起高度(上凸型燃烧室)和减小缸盖上燃烧室高度的方式来满足Atkinson循环汽油机对压缩比的要求。同时为适应紧凑结构减小气门升程、直径(紧凑型燃烧室)。通过三维CFD计算分析,比较了两种燃烧室缸内燃烧及流动特性,发现紧凑型燃烧室能够在火核形成及扩散时期在缸内产生更高的湍动能,有利于加快火焰传播,使燃烧持续期缩短9.8%~24.4%,可显著提高燃油经济性。在混合动力用Atkinson循环发动机开发中使用紧凑型燃烧室,具有重要的应用价值。

关键词：混合动力；Atkinson循环发动机；燃烧室；湍动能

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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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In this review, we summarize the literature from the warm deserts of North America and consider leaf (Anet), soil (Rs), and plant community (aboveground net primary productivity; ANPP) studies from the Mojave, Sonoran, and Chihuahuan Deserts to determine if common trends exist across measurement scales that can be utilized to effectively manage the warm deserts. Furthermore, we investigate the potential management strategies that may increase carbon sequestration or minimize carbon losses in this region. We begin by describing the warm deserts in the southwestern United States and consider climate change projections for this region.

关键词：二氧化碳；气候变化；暖沙漠；封存；碳储存

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The risk of motor vehicle crashes (MVCs) associated with on-the-job operation of motor vehicles or exposure to road traffic hazards affects millions of workers in the United States, and this risk cuts across all industries and occupations. MVCs are consistently the leading cause of worker fatalities, affecting workers who drive all types of motor vehicles during their work day . passenger cars, heavy trucks, fire apparatus, and many others. A wide variety of interventions may be applied to prevent work-related MVCs: administrative controls such as seat belt policies, distracted-driving policies, pre-trip vehicle checks, driver training, reduced travel, and fatigue management; and engineering controls such as more crashworthy vehicles, advanced driver assistance systems, or active safety systems. Questions remain as to which are the most effective interventions to protect workers from risks of work-related MVCs. Through strategic planning, research, collaborations with stakeholders, and communication of research results and prevention, the National Institute for Occupational Safety and Health (NIOSH) is working to ensure that recommended solutions to prevent work-related MVCs and resulting injuries are based on sound research and are clearly communicated to employers and workers. The NIOSH Center for Motor Vehicle Safety (CMVS) is the focal point for activities within the Institute that address this pressing occupational safety problem. The CMVS was designated in December 2010 to strengthen and sustain the Institute's research and prevention activities to reduce work-related motor vehicle crashes and resulting injuries. It is a 'virtual' Center through which researchers from across the Institute and external partners from government, non-governmental organizations (NGOs), academia, labor, and industry bring complementary expertise to identify crash risk factors, develop and evaluate workplace interventions to prevent crashes, and communicate the results to employers and other stakeholders. The NIOSH CMVS is guided by the vision that: All workers who are exposed to hazards of motor vehicle traffic while working have the highest possible levels of protection from the risk of motor vehicle crashes and resulting injuries. The primary purpose of the 5-year strategic plan for the NIOSH CMVS is to define the priority areas for research and prevention initiatives through 2018.

关键词：战略计划；交通安全；工作场所

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Excavators are used to unearth, transport, and unload materials with the help of a bucket fitted to a boom. They move on crawlers or wheels. Excavators are versatile heavy construction machines used for below- and above-ground operations, including land leveling, trench digging, and well sinking. The excavator market in Russia is one of the steadily growing construction equipment markets in EMEA and will post a CAGR of 6.54% during the forecast period. The mega events planned to take place in Russia will accelerate market growth.

关键词：挖掘机；挖掘；运输；装卸材料；多功能；重型工程；俄罗斯市场；建筑设备市场

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An experimental study has been conducted to provide insight into heat transfer to the piston of a light-duty single-cylinder research engine under Conventional Diesel (CDC), Homogeneous Charge Compression Ignition (HCCI), and Reactivity Controlled Compression Ignition (RCCI) combustion regimes. Two fast-response surface thermocouples embedded in the piston top measured transient temperature. A commercial wireless telemetry system was used to transmit thermocouple signals from the moving piston. A detailed comparison was made between the different combustion regimes at a range of engine speed and load conditions. The closed-cycle integrated and peak heat transfer rates were found to be lower for HCCI and RCCI when compared to CDC. Under HCCI operation, the peak heat transfer rate showed sensitivity to the 50% burn location.

关键词：压燃式发动机；传热；活塞；热电偶

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