基于AMESim的脐带缆液压传输特性及等效方法仿真研究

分析脐带缆液压管线传输特性,提出等效方法。应用AMESim建立脐带缆液压管线液压仿真系统,进行仿真模拟,分析仿真结果,研究脐带缆的液压传输特性,并与相似性原理下脐带缆液压传输特性参数进行相对分析,确定脐带缆液压特性参数液阻、液容、液感在液压系统中的表现形式。根据分析结果,确定脐带缆液压传输特性的等效模型的形式,确定液阻、液容、液感的具体等方式,应用AMESim仿真分析了等效方法的等效性,确定了一种脐带缆液压管线的等效模型搭建形式。仿真结果可做为脐带缆液压等效装置搭建的理论参考。     

AC impedance and state-of-charge analysis of alkaline zinc/manganese dioxide primary cells

Alternating current impedance data of alkaline Zn/MnO₂ cells were analysed in view of identification of suitable parameters, which depend on the state-of-charge (SOC) of the cells. The impedance of a slightly discharged cell was found to possess impedance considerably lesser than that of an undischarged cell. The data in the form of Nyquist plot contained an inductance part at very high frequencies, a capacitive semicircle at high frequencies and a diffusion linear spike at low frequencies. The low frequency linear spike gradually transformed into a capacitive semicircle with the decrease of SOC of the cell, which was attributed to the nature of the reactions at the Zn anode. Of several impedance parameters that were examined, equivalent series capacitance (C _s) was found to have a strong dependence on SOC of the alkaline Zn/MnO₂ cells. There was a continuous change in a partially discharged cell during its ageing, which was reflected by transformation of low frequency data into a clear semicircle.     

A Faster One-Dimensional Topological Compaction Algorithm with Jog Insertion

We consider the problem of one-dimensional topological compaction with jog insertions. By combining both geometric and graph-theoretic approaches we present a faster and simpler algorithm to improve over previous results. The compaction algorithm takes as input a sketch consisting of a set F of features and a set W of wires, and minimizes the horizontal width of the sketch while maintaining its routability. The algorithm consists of the following steps: constructing a horizontal constraint graph, computing all possible jog positions, computing the critical path, relocating the features, and reconstructing a new sketch homotopic to the input sketch, which is suitable for detailed routing. The algorithm runs in O(|F| ⋅ |W|) worst-case time and space, which is asymptotically optimal in the worst case. Experimental results are also presented. Received May 16, 1997; revised January 11, 1999.     

Design and research of a three‐phase voltage sensor based on D‐dot principle

In the design of three‐phase D‐dot voltage sensor based on electric field coupling, both effects of both the adjacent phase electric fields and distribution parameters on measurement should be taken into consideration. This paper builds a simulation model and a physical measuring system of a three‐phase sensor, measures the effect of the distribution parameters by the simulation model, and finally finds the transfer function between the input and output voltage signals of the circuit. The measured voltage waveforms and parameters can be reflected by the physical measuring system. Our results provide a theoretical basis for the design of a three‐phase D‐dot voltage sensor. And the measuring system can achieve multipoint synchronous acquisition and ensure less distortion. © 2016 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

继保专用电流互感器特性参数的认识与分析

电力系统继电保护专用的电流互感(下称CT)是在电网发生故障时,正确地将一次量转变成二次量,确保继电保护装置正确动作。若要确保CT在非正常工作状态时的正确工作,就必须对CT的特性参数充分认识及正确运用。对此,通过CT运行事故案例和现场电气试验,取得经验和获得数据,对其加以分析求证,从而正确地选择CT的特性参数。     

腐蚀的电化学研究现状

基于电化学原理发展起来的电化学测试技术，如极化曲线分析法，交流阻抗分析法，电化学噪声分析法和Kelvin探针技术等，是研究腐蚀的重要手段，近些年有了很大的进展。掌握这些技术的原理及应用领域的进步，将有助于对腐蚀与防护技术的深入研究和开发。     

基于等效粒径概念的非均匀沙起动条件研究

摘要：分析表明运用等效粒径概念进行非均匀沙起动临界条件计算是很简便的。基于Parker提出的非均匀沙起动两种极限状况，提出了一个简单的等效粒径表达式。通过取不同的荫蔽参数，该等效粒径表达式可近似表达八家有代表性的非均匀沙起动公式的荫蔽暴露作用，这表明由于床沙特性和粗化程度的不同，荫蔽参数本应是不同的。用韩其为整理的长江寸滩站卵石起动资料，回归得到寸滩站卵石起动计算公式。该公式形式简单,运用于王兴奎整理的范围更宽的寸滩站资料时，表现良好。为长江寸滩站合理选用卵石起动条件提供了依据。     

Prediction of antifreeze critical strength of infant age concrete

The rule of infant age concrete strength development under low temperature and complex affecting factors is researched. An efficient and reliable mathematical forecast model is set up to predict the infant age concrete antifreeze critical strength under low temperature at construction site. On the basis of the revision of concrete equivalent coefficient under complex influencing factors, least-squares curve-fitting method is applied to approximate the concrete strength under standard curing and the forecast formula of concrete compressive strength could be obtained under natural temperature condition by various effects. When the amounts of double-doped are 10% fly ashes and 4% silica fumes as coment replacement, the antifreeze critical strength changes form 3.5-4.1MPa under different low temperature curing. The equivalent coefficient correction formula of concrete under low temperature affected by various factors could be obtained. The obtained equivalent coefficient is suitable for calculating the strength which is between 10% to 40% of standard strength and the curing temperature from 5-20 ℃. The forecast value of concrete antifreeze critical strength under low temperature could be achieved by combining the concrete antifreeze critical strength value with the compressive strength forecast of infant age concrete under low temperature. Then the theory for construction quality control under low temperature is provided.     

Electroehemieal Behavior of Antimicrobial Stainless Steel Bearing Copper in Sulfate Reducing Bacterial Medium

The electrochemical characteristic of antimicrobial stainless steel bearing copper NSSAM3 in sulfate reducing bacterial （SRB） was investigated by electrochemical impedance spectroscopy （EIS） and potentiodynamic polarization. The results show that inoculation of SRB into the culture medium significantly affects the anodic polarization behavior of NSSAM3 and accelerates anodic depolarization process, however, it has little effect on cathodic polarization curves of NSSAM3. Under the same exposure time, the anodic polarization curves of NSSAM3 in culture medium with SRB are in anodic active dissolution state when anodic polarization potential value is below 0 V（SCE）, whose anodic polarization current density is bigger than that of in culture medium without SRB. Moreover, when the concentration of Cu^2＋ in SRB medium increases, anodic polarization current density of NSSAM3 decreases and polarization resistance increases with increasing time. Scanning electron microscope （SEM） observations indicate that SRB unevenly attaches on the surface of NSSAM3, and induces the sensitivity to local corrosion.     

The influence of some new 2,5-disubstituted 1,3,4-thiadiazoles on the corrosion behaviour of mild steel in 1 M HCl solution: AC impedance study and theoretical approach

The new 2,5-disubstituted 1,3,4-thiadiazoles were investigated as corrosion inhibitors of mild steel in 1 M HCl using AC impedance technique. Four of these compounds exhibit good inhibition properties, while two of them, 2,5-bis(4-nitrophenyl)-1,3,4-thiadiazole and 2,5-bis(4-chlorophenyl)-1,3,4-thiadiazole, stimulate the corrosion process especially at low concentrations. The experimental data obtained from this method show a frequency distribution and therefore a modelling element with frequency dispersion behaviour, a constant phase element (CPE) has been used. Possible correlations between experimental inhibition efficiencies and quantum chemical parameters such as dipole moment (μ), highest occupied (E_HOMO) and lowest unoccupied (E_LUMO) molecular orbitals were investigated. The models of the inhibitors were optimised with the Density Functional Theory formalism (DFT) using hybrid B3LYP/6-31G (2d,2p) as a higher level of theory. The Quantitative Structure Activity Relationship (QSAR) approach has been used and composite index of some quantum chemical parameters were constructed in order to characterize the inhibition performance of the tested molecules.