液氮汽车的可行性分析

基于朗肯循环过程，对液氮驱动汽车的可行性进行了理论研究，研究了不同的初始膨胀压力的温度下，分别进行等温膨胀和绝热膨胀时，低温发动机所能获得的单位制冷可用能和相应的Yong效率，并对采用甲烷-液氮两级联合的朗肯循环进行了理论分析，提出了进一步提高其性能的途径。从经济性的角度，认为液氮汽车相对于其它零排放汽车有优势。     

长江干流河口地区枯水季水量分配研究

针对枯水年枯水季,因河道径流量较少,盐水入侵的频率和强度显著提高而引起的长江河口沿岸地区生产生活用水安全,文中结合长江口地区水资源利用和水环境现状,以大通以下长江干流地区在枯水季水量分配为实例,在初步预测未来河口地区水资源需求的基础上,提出长江口地区水资源配置的思路、方法及方案框架。     

Inertia moment identification in the average speed-type instantaneous speed observer

In recent servomotor control systems using highspeed microprocessors, it is difficult to obtain accurate speed information by using a low-resolution shaft encoder because encoder pulses are very sparse in the low-speed range. To overcome this problem, the instantaneous speed observer is proposed, system stability is improved, and strong disturbance rejection control is realized. However, when the inertia moment changes, the estimated instantaneous speed has error because the observer uses the nominal value of the inertia moment to calculate the instantaneous speed. For this reason, the identification method of the inertia moment for the “position input-type” speed observer is proposed but it operated at about 50 rpm speed command. This paper proposes some novel identification methods for the “average speed-input type” instantaneous speed observer and identifies the inertia moment in the very low speed range below 1 rpm.     

拱坝应力控制标准研究

实践经验表明，我国现行混凝土拱坝设计规范存在下列问题：应力标准与建筑物重要性无关，允许主拉应力与混凝土强度无关，拱坝应力分析主要采用多拱梁法和有限无法，但同一拱坝用不同多拱梁法程序计算的结果并不一致，尤其是拉应力相差较多，有限元法具有较强计算功能，但由于应力集中，计算的应力值很大，缺乏合适的应力控制标准。通过对影响拱坝应力控制标准的各项因素进行较深入的分析，提出了一套新的拱坝应力控制标准，使上述各问题都得到了解决。     

MTMD减震结构体系的频域分析

将主结构简化为串联多自由度模型,通过对主结构稳态响应的频域传递函数的模值来分析MTMD控制效果。主结构稳态响应的频域传递函数分别采用以下三种方法求取:1)推导结构系统振动方程,将其从时域转化为频域,推导频域传递函数;2)将MTMD系统对主结构的反力与地震荷载共同作为主结构的荷载输入,根据MTMD的反力为各阶模态耦合对结构进行控制的方法求取频域传递函数;3)根据MTMD的反力为各阶模态非耦合对结构进行控制的方法求取频域传递函数。利用以上方法分析MTMD系统对主结构的单模态和多模态进行控制的控制效果。根据非耦合控制作用的频域传递函数提出惯性质量参与量。给出一算例,并且给出时程分析的结果加以比较验证。     

Performance analysis and interoperability issue of consolidation algorithms in point‐to‐multipoint ABR services

In this paper we propose a performance analysis of the consolidation algorithms in point‐to‐multipoint ABR services in ATM network. We also present a new efficient consolidation algorithm, which overcomes some drawbacks of the previous works. The performance of the previous works and our proposed consolidation algorithms are analysed mathematically. General equations for calculating the response time and allowed cell rate of the source are derived. The derived equations show relatively good agreement with simulation results and can be applied for using in various network topologies. In addition, the interoperability issue in multicast available bit rate (ABR) is investigated. It is found that the branch points implemented with different consolidation algorithms can work interoperably. It is concluded from the simulation results that the performance of the point‐to‐multipoint ABR services is dominated by the most upper stream branch point (the nearest one to the source), therefore, in order to avoid the consolidation noise and get a faster response in the network, the most upper stream branch point has to be implemented with a high accuracy consolidation algorithm while the lower stream branch point(s) should be implemented with a fast response consolidation algorithm with a less degree of complexity. Copyright © 2002 John Wiley & Sons, Ltd.     

企业生产怎样保证对市场的快速反应

通过对企业生产作业计划的创新，使其及时准确地反映加工产品在生产线各工序的移动及在制品存量；利用计量经济学基本原理，设计出生产期量化标准的数字模型，从而有效控制生产各衔接环节物流存量并降低其运行惯性；通过信息化改造，提高企业信息传递的通透性和时实性，确保企业生产对市场的快速反应。     

The inertia tensor versus static moment and mass in perceiving length and heaviness of hand-wielded rods.

In 2 experiments, participants haptically estimated length and heaviness of handheld rods while wielding without seeing them. The sets of rods had been constructed such that variation of static moment and the 1st eigenvalue of the inertia tensor (It) were separated. Consistent with previous findings, perceived rod length correlated strongly with It. However, multiple regressions on current data as well as data from previous studies showed a comparable strong correlation between perceived rod length and static moment plus mass. Contrary to previous findings, perceived heaviness correlated strongly with static moment and only weakly with the eigenvalues of the inertia tensor. These results suggest that the inertia tensor does not provide the sole foundation for a theory of dynamic touch. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Studies of cyclic and linear poly(dimethyl-siloxanes): 11. Shapes of ring and chain molecules

The equilibrium shapes of cyclic and linear poly(dimethyl siloxane) (PDMS) molecules have been investigated using Flory, Crescenzi and Mark's rotational isomeric state model, together with a Monte Carlo method described previously. The principal axes of the equivalent ellipsoids have been computed and the major change on ring formation was found to be a reduction in the longest axis of the ellipsoid. This result is in agreement with previous studies of other ring molecules. The shapes of the cyclics $\text{[(}\text{CH}{}_3\text{)}{}_2\text{SiO}\text{]}{}_{\mathrm{<mtext>w</mtext><mtext>2</mtext>}}$ in the region w=20 are disc-like and this observation is related to the different bond angles at silicon and oxygen atoms. Bulk densities and refractive indices of PDMS rings are discussed in relation to the calculated molecular shapes. Histograms are used to illustrate the proportional frequency functions of the radii of gyration and their components s_x, s_y and s_z.     

三级齿轮传动最佳传动比配比的研究

从理论上研究了三级齿轮传动转动惯量最小时的最佳传动比配比，得出了每一级传动比的计算表达式，并结合实例给出了设计步骤。