Topological design sensitivity on the air bearing surface of head slider

In this study, a topological design sensitivity of the air bearing surface (ABS) is suggested by using an adjoint variable method. The discrete form of the generalized lubrication equation based on a control volume formulation is used as a compatible condition. A residual function of the slider is considered as an equality constraint function, which represents the slider in equilibrium. The slider thickness parameters at all grid cells are chosen as design variables since they are the topological parameters determining the ABS shape. Then, a complicated adjoint variable equation is formulated to directly handle the highly nonlinear and asymmetric coefficient matrix and vector in the discrete system equation of air-lubricated slider bearings. An alternating direction implicit (ADI) scheme is utilized for the numerical calculation. This is an efficient iterative solver to solve large-scale problem in special band storage. Then, a computer program is developed and applied to a slider model of a sophisticated shape. The simulation results of design sensitivity analysis (DSA) are directly compared with those of FDM at the randomly selected grid cells to show the effectiveness of the proposed approach. The overall distribution of DSA results are reported, clearly showing the region on the ABS where special attention should be given during the manufacturing process.     

Reduced heat stress in offices in the tropics using solar powered drying of the supply air

Many solutions to indoor climate problems known from developed countries may have prohibitive installation and running costs in developing countries. The purpose was to develop a low-cost solution to heat stress in a hot and humid environment based on solar powered drying of supply air. Dry supply air may facilitate personal cooling by increased evaporation of sweat. Heat acclimatized people with efficient sweating may in particular benefit from this cooling. A prototype solar powered supply system for dried-only air was made. Air from the system was mixed with room air, heated to six different combinations of temperature and humidity and led to Personal Units for Ventilation and Cooling (PUVAC) in six cubicles simulating office workplaces. A total of 123 heat acclimatized subjects were exposed 45 min in each of the cubicles. A model for the combined effect of operative temperature of room, moisture content of room air, temperature of supply air and moisture content of supply air was developed based on the experiments. Reduction of moisture content in the supply air by 1.6 g/kg had the same effect as lowering the operative temperature by 1 degree C. The solar-powered system for supplying dry air is a low-cost alternative to traditional air conditioning in hot and humid regions.     

Characterization of structural effects from above-ground explosion using coupled numerical simulation

The response of a building structure to a nearby explosion is complicated by the drastic spatial and time variation of the blast load. Existing studies on the structural responses to explosion effects often employ simplified structural model with assumed loading patterns, such as element-based (beam-column, slab) models, single degree of freedom or lumped mass systems. The validity of a simplified approach depends on whether the governing response and failure mechanisms are well represented in the simplified scheme. For such validation more sophisticated models are required. This paper presents a numerical simulation study aiming to characterize the various structural effects of above-ground explosions. A coupled numerical approach with combined Lagrangian and Eulerian methods is adopted to allow for the incorporation of the essential processes, namely the explosion, shock wave propagation, shock wave-structure interaction and structural response, in the same model. The computational domain extends to the soil around the base of the structure, allowing also for an evaluation of the significance of the ground vibration effect. Results show that for a typical above-ground explosion scenario, the critical structural damage is dominated by air shock loading, while the ground shock induces only some additional vibration whose structural effect is minor. The distribution of structural damage tends to be governed by member level effects on the front face of the structure, whereas the global dynamic response of the system appears to be insignificant. Similar modeling approach may be applied to explore other blast-induced complex response phenomena.     

Air cargo pickup schedule for single delivery location

In this paper, various deterministic models for determining optimal pickup times for air cargo from an airport and delivering it to a local distribution center for a global manufacturer are presented. The arrival times of the flights that can potentially bring air cargo are assumed to be deterministic and known. In addition, the custom clearance time for the air cargo and the traveling time from the airport to the local distribution center are assumed to be deterministic and known. These models are formulated mathematically as linear binary integer programming models without air cargo weight considerations. Deterministic formulations without air cargo weight information are shown to be related to the p-Median problem. The deterministic formulation of air cargo pickup times with air cargo weight consideration is shown to be a nonlinear binary integer programming model. The solutions of these models serve as an initial starting point to solve the stochastic problem with random arrival times of the flights and random custom clearance times and travel times.     

分布式环境下CAN网桥的实现和性能分析

本文讨论了CAN网桥的适用性．并在SAE标准参数的基础上．使其可用于实时控制．同时研究了利用网桥互连的CAN系统在分布式环境下的特性。     

热采锅炉配风自动控制系统

分析了国产热采锅炉配风系统存在的问题,设计了烟气含氧量自动控制系统,实现热采锅炉最佳配风,并取得了满意的应用效果。     

家用空调制冷系统部件的机械强度设计原理第1部分失效形式与失效准则

本文介绍了家用空调制冷系统中承压部件强度失效的几种常见类型,以及承压部件破损导致制冷剂发生大量泄漏情况下,按爆炸能量对压力安全风险划分的方法,并介绍了强度失效的几种判定准则.     

交流电桥灵敏度问题的探讨

通过理论和实验证明,阐述了提高交流电桥灵敏度的方法和测量电路的选择,从而减少实验的系统误差.     

桥式弧焊逆变器主电路拓扑结构分析

通过对ICBT等为开关器件的新一代弧焊逆变器主电路的拓扑结构进行分析和研究，探讨了两种典型拓扑结构的特征：全桥逆变器、移相全桥逆变嚣。     

无线局域网在医疗系统中的应用

分析了目前医院信息系统(HIS)的现状，结合现在医院采用的计算机信息管理系统，对有线与无线相结合的局域网技术进行了研究，使医疗行业实现了患者与医护人员、管理者与医护人员随时随地传递信息、以及医院间医疗数据共享、远程会诊，提高了就诊和处理病患的速度，通过移动上网办公来为病人提供更加优质的医疗服务，加快了医疗系统的信息化建设，它为提高患者的治愈率、满意率起到了积极、有效作用，提高了医院管理水平和快速反应能力，为数字化医疗开辟了道路.