An investigation of induced voltages to an underground gas pipeline from an overhead transmission line

This paper investigates induced voltage characteristics from an overhead transmission line by applying a method of modeling of induced voltages proposed by the authors. EMTP simulation results obtained by the modeling method agree with analytical results obtained from a well‐known formula. The induced voltages are significantly dependent on the configuration of the overhead line. A horizontal line induces the largest voltage in a gas pipeline, and the voltage induced by a vertical twin‐circuit line is about 20% smaller than that induced by a vertical single‐circuit line. The method is applied to a real pipeline system and the simulation results show reasonable agreement with field test results. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 164(1): 43–51, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20465     

Series resonant ZCS‐PFM DC‐DC power converter with high‐frequency high‐voltage transformer link for high‐power magnetron drive

This paper presents a single lossless inductive snubber‐assisted ZCS‐PFM series resonant DC‐DC power converter with a high‐frequency high‐voltage transformer link for industrial‐use high‐power magnetron drive. The current flowing through the active power switches rises gradually at a turned‐on transient state with the aid of a single lossless snubber inductor, and ZCS turn‐on commutation based on overlapping current can be achieved via the wide range pulse frequency modulation control scheme. The high‐frequency high‐voltage transformer primary side resonant current always becomes continuous operation mode, by electromagnetic loose coupling design of the high‐frequency high‐voltage transformer and the magnetizing inductance of the high‐frequency high‐voltage transformer. As a result, this high‐voltage power converter circuit for the magnetron can achieve a complete zero current soft switching under the condition of broad width gate voltage signals. Furthermore, this high‐voltage DC‐DC power converter circuit can regulate the output power from zero to full over audible frequency range via the two resonant frequency circuit design. Its operating performances are evaluated and discussed on the basis of the power loss analysis simulation and the experimental results from a practical point of view. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 153(3): 79–87, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20126     

担载型含稀土三组份体系在二氧化碳甲烷化反应中的催化性能

用浸渍法制备了一系列氧化锆担载的含稀土Ⅷ族金属催化剂，对其在二氧化碳甲烷化过程中的催化活性作了研究，并用漫反射紫外可见光谱，ＦＴＩＲ等手段对催化剂作了表征。结果表明，含稀土新型催化剂具有催化活性高，目标产物选择性好等优点；稀土主要以氧化物形式存在于催化剂表面，参与对氢及表面含碳物种的吸附及活化；含稀土三组份催化剂的活性与所添加稀土三价离子的４ｆ电子数有关。     

Characteristics and classification of high-current fault arcs on distribution systems

When a fault occurs on transmission or distribution systems due to lightning or overvoltage, often an arc discharge occurs at the fault point. The arc discharge, which is caused by a fault current, has a high current, high temperature, strong light emission, etc., thus it sometimes causes heavy damages to electric power equipment. The arc discharge is influenced by the conditions around the arcs, i.e., gas, insulation materials, gap length, weather, etc. Also, the arc voltage along the arc column indicates the characteristics of the arc. If the voltage waveforms of the arcs caused by the fault on transmission or distribution systems are classified, it is possible to find the location and the equipment where the fault occurred. In this paper, the arc voltage data in 6-kV class XLPE cables and 6-kV class overhead lines are analyzed and an artificial neural network method is applied to classify the arc voltage waveforms. The results obtained from the six artificial neural networks developed show that the artificial neural network method is effective for classification of arc voltage waveforms if adequate input parameters are selected.     

Stability of AB5-type hydrogen storage alloys

In this paper, we deduced an empirical equation for predicting the stabilities of the hydrides of AB₅-type compounds with the consideration of the effects of geometrical factor and electric factor. The theoretical curves derived from this equation are in good agreement with the test results of La_1−xCa_xNi₅, Ml_1−xCa_xNi₅ and La_1−xCe_xNi₅ compounds. With this model, we can easily interpret the phenomenon that the initial partial substitution of R by Ca in R_1−xCa_xNi₅ (R is rare earth metal) compounds cause an increase of hydrogen desorption pressure to a maximum value, whereas in the range of larger Ca content x the hydrogen desorption pressure decreases with increasing x.     

萃取预分离法分离富铕中钇矿新工艺

采用一种新的串级萃取方式--萃取预分离法分离富铕中钇矿的新工艺.原料首先流入十几的三出口预先粗分离工艺,其萃余液La～Gd(TbDy)直接流入Nd/Sm工艺;中间出口流入(Gd)Tb～HoY(Er)Gd～Dy/Ho～LuY细分离工艺;出口负载有机相(Ho)Er～LuY流入Gd～Dy/Ho～LuY的洗涤段.结果表明,新工艺的粗分离工艺将占原料约70%的La～Gd(TbDy)预分离掉,使流入Gd～Dy/Ho～LuY工艺的稀土量减少约70%;由于Gd～Dy/Ho～LuY分组的萃余液GdTbDy含Ho2O3小于0.03%,省去原工艺的GdTbDy/HoY分离;新工艺的处理能力提高30%,酸碱消耗减少20%以上,贵重稀土元素Eu和Tb的存槽量大大减少.     

变频开关电源Fuzzy-PID控制器的设计

针对感应式变频开关电源在对金属材料进行热处理过程中，负载的等效参数和谐振频率发生变化，而变频电源的输出频率不能及时调整和跟踪的问题，结合PID和Fuzzy控制技术的优点，设计Fuzzy-PID控制器对变频电源进行控制，在大偏差时用Fuzzy控制，在小偏差时用PID调节。Fuzzy-PID控制器以单片机8098为核心，采用SPWM专用芯片SA4828，实现变频开关电源的电压、电流双闭环控制，使变频电源不仅具有较快的动态响应、更小的超调，并且具有较高的稳态精度和频率跟踪控制特性。     

稀土稳定氧化锆超细粉末的合成机理研究

依据Al(Ⅲ )、Zr(Ⅳ )的水解聚合机理 ,把锆、铝和钇的无机盐溶液按一定组成混合在一起 ,通过加入乙二醇作为络合剂和调节溶液的PH值来获得溶胶 ,并直接蒸馏溶胶来获得干凝胶 ,最后制得ZrO2 (Y2 O3 ) -Al2 O3 系粉末。研究结果表明 :该工艺不仅制粉时间快、成本低、产量大 ,而且粒子均匀 ,粒径在 2 0～ 5 0nm之间 ,具有一定的可行性     

Structure and properties of polyimide‐bonded magnets processed from prepolymers based on diacetyl derivatives of aromatic diamines and dianhydrides

We report a novel method of polyimide (PI) synthesis from prepolymers based on dianhydrides and diacetyl derivatives of aromatic diamines that facilitate the preparation of a melt processable mixture at 300 ± 10°C of the prepolymer and magnetic Nd‐Fe‐B alloy to provide PI‐bonded magnets with enhanced properties. It is shown that chemical structure of the prepolymers strongly influences viscosity behavior via crystallization of the oligoimide in the melt, leading to formation of PI with rigid‐rod like structure. This structural ordering of the prepolymers based on diacetyl derivative of diamine used in this study, if not controlled, leads to exponential increase of melt viscosity with time, making it practically impossible to prepare melt processable mixture of the magnetic particles and the PI prepolymers at elevated temperatures. The results obtained demonstrate that appropriate dianhydrides and diacetyl derivatives of diamines that do not lead to crystallization of oligoimides in prepolymer mixture can be used under controlled processing conditions to prepare melt‐processable PI‐bonded magnets containing rigid‐rod like PI structure that significantly increases thermal stability of the magnets. The temperature dependencies of the magnetic properties of the PI‐bonded magnets under conditions that they are likely to encounter during their service life were found to be remarkably similar to that of commercial thermoplastic magnets such as injection‐molded nylon magnets. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 478–485, 2006     

Studies of structure and cycleability of LiMn2O4 and LiNd0.01Mn1.99O4 as cathode for Li-ion batteries

Lithium manganese oxides LiMn₂O₄ and rare earth elements doped LiNd_0.01Mn_1.99O₄ were synthesized by microwave method. The structure and the electrochemical performances of the samples were characterized. XRD data shows both samples exhibit the same pure spinel phase. But due to the introduction of Nd³⁺ ion into the unit cell, the lattice parameter of the Nd-doped spinel was larger than that of the undoped one. The two samples had a similar morphology including small particle size and homogeneous particle distribution as tested by SEM. The cyclic voltammmetry and constant-current charge-discharge tested that Nd-doped spinel displayed a better reversibility and cycleability.