急性炎性疾病患者乳酸林格氏液液体动力学

目的:探索炎性疾病患者的乳酸林格氏液（Ringer's lactate,RL）液体动力学特征以及炎性生物标记物是否可以作为协变量影响RL分布和排泄。方法:本研究为前瞻性队列研究。选择40例美国麻醉医师分级（ASA）I-II级，腹腔镜下择期胆囊切除术（胆囊炎组，n=20）或者腹腔镜下急诊阑尾切除术（阑尾炎组，n=20）。所有患者麻醉诱导前开始输注RL，按15 mL/kg，35 min内输毕。采用酶联免疫（enzyme-linked immunosorbent assay,ELISA）方法测定血浆炎症（TNF-α,IL-10和CRP）或者内皮损伤生物标记物（syndecan-1,SDC-1）；利用血红蛋白（Hb）稀释-时间曲线和尿量，使用Phoenix软件，采用非线性混合效应模型分析计算RL液体动力学参数和协变量的影响。结果:与胆囊炎组相比，阑尾炎组RL从组织间隙到血浆的转运速率常数（k21）显著降低（14×10-3min-1 versus 35×10-3min-1;P=0.012）。阑尾炎组C反应蛋白（CRP）升高［中位数38.1(1.8-143.6) μg/mL versus 1.3(0.1-159.0) μg/mL;P<0.001］；与清醒状态相比，麻醉期间（输液开始后30～45 min），液体从中央室中到外周室的转运速率常数（k12）显著增加（57×10-3min-1 versus 32×10-3min-1；P<0.01）。清除速率常数（k10）降低90%（0.6×10-3min-1 versus 5.3×10-3min-1;P<0.001）。无论在清醒状态还是麻醉状态下低血压均能降低液体清除；炎症或者内膜损伤的生物标记物不能作为显著影响RL液体动力学参数的协变量。结论:阑尾炎或者胆囊炎患者术前输入液体后“炎症反应的生物标记物”不是RL的液体动力学的协变量，但是两组患者中，全身麻醉期间输入液体的清除率下降。     

带电清洗剂对绝缘子用硅橡胶的溶胀效应及其影响研究

复合支柱绝缘绝缘子由于具有优异的防污性能,在直流换流站得到了广泛应用,但其在空间电荷和静电效应下积污严重而存在大面积污闪风险。为了评估复合支柱绝缘子带电绝缘清洗的可行性,对硅橡胶在新型绝缘清洗下的溶胀特性及其对硅橡胶的电气性能、力学性能以及憎水性的影响开展了试验分析。研究结果表明:硅橡胶溶胀随着溶胀时间的增加溶胀指数和直径增长率持续增大,浸泡时间20 min时圆形硅橡胶试样的直径增长率为4.7%、溶胀指数为6.8%。硅橡胶的复介电常数、复电容、介质损耗因素随着频率、溶胀指数增大而减小;在10-2~103Hz频域范围内硅橡胶溶胀不会造成介电性能下降。硅橡胶溶胀对憎水性和憎水迁移性无明显影响,干燥洁净硅橡胶溶胀前后接触角θ平均值在92°~98°范围内浮动,人工积污并经过憎水迁移后θ平均值在119°~128°范围内浮动。硅橡胶在发生溶胀后其力学性能小幅度下降,溶胀20 min的其断裂拉伸强度下降2%。试验结果表明硅橡胶在清洗剂中溶胀度受浸润时间影响较大,溶胀效应对憎水性、电气和力学性能影响较小,可通过采用易挥发配方或强对流措施控制清洗剂残留对硅橡胶的影响。     

玻纤格栅面层加筋位置的数值模拟和试验研究

从车辙机理分析入手,由ANSYS确定面层内部最大剪应力位置,再通过不同层位室内车辙试验的对比验证,得到了工程路面铺筑的最佳位置,可为工程实际提供参考依据。     

An algorithm for function restoration using eigenvectors†

This paper presents an algorithm for the restoration of the characteristics of a function from a finite number of observed points. The algorithm uses the eigenvectors of the Gramian of the observed vectors and is based on the assumption that the function to be constructed can be represented by a specified form. Convergence of the algorithm is proved for the noiseless case. When noise is present, a bound for the error is obtained. For functions not representable in the assumed form, the algorithm can be used to test the non-representability of the function. A numerical example is given to illustrate the theoretical investigation.     

A note on the potential function algorithm for pattern classification†

A system design engineer often resorts to redundancies while maximizing the probability of success of a system designed to perform a certain job over a period, This will have to be done within the resources available. The problem of maximizing system reliability, subject to some linear constraints such as cost, weight or volume, is considered in this paper- The usual problem is transformed to a suitable form and the least square concept is used to develop a solution technique. This type of approach is found to be very simple and faster than earlier methods although the solution is an approximate one.     

A Modification of the Coates Gain Formula for the Analysis of Linear Systems

In this paper, the Coates flow-graph gain formula is modified by the introduction of the loop-set and the two-loop-set, baaed on the concepts of the tree and the two-tree in network topology. The analogy is evident by observing that the two-trees T _ij of a given graph G can be obtained by coalescing vertices i and j of G and thon removing the self-loops. In a similar manner, the two-loop-sets can be obtained from the flow graph by first modifying the graph and then obtaining the loop-sets of tho modified graph. Because of such modification, the derivation of tho gain formula is considerably simplified. Consequently, the evaluation of the terms in the formula becomes easier. Finally, a simple method of determining the number of terms in the formula is derived as a check against possible omission of terms due to carelessness.     

Effect of Laser Power on the Cladding Temperature Field and the Heat Affected Zone

 Abstract: In this paper, H13 powder is cladded on P20 base during continuous CO2 laser, the influence of processing technologies such as the laser power is analyzed. The 3-D model of synchronous powder feeding is established under Gauss heat source, the simulation results are compared with the experimental data. The results show that the temperature field and the size of heat affected zone are affected by laser power. In the heat affected zone, experimental sizes are compared with simulative sizes, the average errors in width and in depth are 15% and 4.5%, respectively.     

Singular extremal control problem with time delay

In this article, the singular extremal control problem with time delay is studied from the viewpoint of the calculus of variation and matrix theory. Some sufficient conditions for the non-negativity of the second variation are obtained for an optimal control problem with a delayed state vector. The hypothesis of Hass is first assumed, and the total singular situation of Jacobson and Bell is also considered. A second-order necessary condition for optimality is also presented.     

Describing function for servomechanism with backlash and multiple non-linearities †

The paper presents a new describing function for a servomechanism which employs a motor driving an inertia load subject to combined Coulomb and viscous frictions, through gearing having backlash. It is shown that describing functions for various types of backlash phenomena reported in the literature can be considered as special cases of the describing function obtained in this paper.