内燃机优化设计研究现状与展望

综述了内燃机优化设计理论的研究和应用现状、进展。着重讨论内燃机主要零部件、工作过程以及内燃机动力学、摩擦学等方面的优化设计研究工作，展望了内燃机优化设计理论和应用的发展动向及若干重要问题。     

三自由度并联姿态测量机构及其运动学参数最优化设计

提出了基于并联结构的三自由度姿态测量机构，将其连接到三自由度串联结构位置测量装置末端可以实现对被测物体六自由度位姿的综合测量。该测量机构克服了并联机构运动学正解的困难，得到运动平台姿态坐标参数的显式解。建立了基于全微分理论的姿态测量机构坐标参数误差模型，实现机构运动学参数的优化设计。误差因子分析使得机构运动学参数设计更为合理。     

电压暂降损失风险规避机制与保险方案研究

半导体、平板显示器生产厂家等敏感用户对电压暂降、短时电压中断等事件型电能质量扰动非常敏感,面临巨大损失风险,因此研究用户损失风险规避机制和解决方案是重要课题。首先,在对某高新技术园区内5家敏感用户经历的电压暂降、导致的损失及其原因进行调查统计;其次,分析与用户损失风险事件相关各方的权力、义务和利益诉求,提出由地方政府、电力部门、用户和第三方保险机构不同程度参与的双边参与和多方参与的风险规避机制;再次,研究用户损失风险事件的特点和可保性条件,根据可保性条件不满足程度,在多方参与机制下,设计一套保险方案,并对保险算法进行详细研究;最后,对5家敏感用户进行实证分析,结果证明,该文提出的风险规避机制和保险方案具有可行性和合理性。     

塔式起重机吊臂和平衡臂的振动分析

以QTZ400型塔式起重机为例，建立其吊臂和平衡臂系统的振动模型，分析影响固有频率的因素，并详细地阐述了进行振动分析在塔式起重机设计中的必要性。     

Numerical analysis of different ventilation schemes during the construction process of inclined tunnel groups at the Changheba Hydropower Station,China

During the excavation process of underground caverns, the rational selection of the ventilation scheme is very important for the safety and health of construction workers. The flood discharge tunnel groups at the Changheba Hydropower Station are selected as a case to study the design of ventilation schemes in inclined tunnel groups; these groups are characterized by a gradient of approximately 10% and a complex intersecting relationship among the tunnels. The Computational Fluid Dynamics (CFD) method is used to simulate the fluid dynamics in tunnel groups when different ventilation schemes are employed. Four ventilation schemes with the same duct at different positions along the transverse section are formulated, and the scheme approaching the right side with most of the construction adits is adopted in engineering after a comparative analysis, as it offers a well-distributed velocity field and sufficient security distance. The study reveals that flow vortices appear in the tunnels with a long axis length ranging from 5 m to 20 m; the observation that the flow velocity on the transverse sections is away from the heading face indicates that a low-velocity area is always present in the vicinity of an air duct, and the security distance on the upstream side is 60% shorter than on the downstream side with the same air-blower when the tunnels have a 10% gradient. In addition, when the excavation distance rises 200 m, the ventilation condition in the tunnels, especially in the areas around tunnel intersections, is greatly improved by the completion of pilot tunnels and shafts in advance.     

Nighttime maintenance of the equatorial ionization by F‐region polarization field

Abstract

The east‐west plasma drift produced by the F‐region dynamo which has been proposed by Rishbeth(16) is included in the continuity equation of electron density, together with other transport and photo‐chemical processes. The numerical solution of the equation reveals that the inclusion of zonal drift has an effect of increasing the maximum electron density N_m during the night, especially just before sunrise. The height h_m of N_m is also increased but at earlier hours. The reasons for these effects are discussed briefly.     

Optimal Control of Finite‐Valued Networks

Control of finite‐valued networks, including Boolean networks, is currently a hot topic. In this paper the optimization of the networks with time‐discounted performance criterion is discussed. The problem is formulated as a finite strategy game between human and machine. It is first proved that the optimal strategy can be found in the set of essentially periodic strategies, which makes the problem finitely computable, though the computational complexity of exhaustion might be a severe problem. Then an efficient numerical method is develossped to solve the problem. Some interesting examples are presented to demonstrate the efficiency of our results.     

睢宁水厂取水设计方案比选

睢宁水厂取水工程设计规模10万m3/d,水源取自庆安水库,采用两种取水方案进行比较,方案一为框架式取水头部、架空虹吸钢管引水;方案二为箱式取水头部、钢管埋地敷设,通过两种方案比较,得出了方案二具有投资低,施工方便及安全性高的优点,并针对该方案施工中的要点提出相应的技术措施,为取水工程的设计提供参考。     

Adaptive nonparametric CUSUM scheme for detecting unknown shifts in location

In this paper, we provide a sequential rank-based adaptive nonparametric cumulative sum control chart for detecting a range of shifts in the location parameter. This chart is a self-starting scheme, and thus can be used to monitor processes at the start-up stages rather than having to wait for the accumulation of sufficiently large calibration samples. It does not require any prior knowledge of the underlying distribution. The choice of the chart parameters is studied and a simulation study demonstrates that the proposed control chart not only performs robustly for different distributions, but also efficiently detects various magnitudes of shifts. An illustrative example is also given to introduce the implementation of this proposed control chart.