基于电阻仿真的无线传感器风能采集方法研究

针对目前无线传感器风能采集效率低和传统最大功率点跟踪算法(MPPT)不适用于微型系统的现状,提出一种基于电阻仿真的无线传感器风能采集方法。重点研究了电阻仿真技术,通过负载阻抗来模拟风机的源阻抗,使得电源和负载之间能够达到良好的阻抗匹配,保证在任何运行风速下采集到的功率都是最大值,从而达到提高无线传感器风能采集效率、延长其工作寿命的目的。最后通过实验,验证了该方法的有效性。

CX盆地露头岩样电阻率测试与分析

本次实验的主要目的是对 CX地区露头完好的岩样进行电阻率测试 ,提出了一种利用露头岩样电阻率绘制模拟地层条件下仿真电阻率测井曲线的新方法。该方法的主要思路是 :1在 CX地区选取一条露头出露较完好的地质剖面 ,在野外进行详细的岩性、地层产状和厚度描述 ,并采集露头岩石标本。 2对所取岩样进行常温常压下的密度、孔隙度和电阻率测试 ,并选部分代表一定岩性的岩样进行模拟地层环境 (压力、饱和度、矿化度 )下的电阻率测试 ;3分析地层条件下的测试结果 ,得出该地区电阻率随饱和度、压力及矿化度变化规律的经验公式 ;4利用地质剖面的岩性和厚度资料 (由许效松等提供 )及常温常压下地表岩样测试资料 ,根据所得到的经验公式计算出地层条件下的岩石电阻率并模拟出仿真电阻率测井曲线。所得到的电阻率模拟测井曲线的效果较好 ,尽管所测试的岩石资料来自 CX盆地 。

高压断路器弧触头动态接触电阻研究

SF_6高压断路器触头间的动态接触电阻是反映SF6高压断路器弧触头烧蚀程度的一个重要参数。研究弧触头动态接触电阻与弧触头的烧蚀程度之间的关系具有重要意义。基于电接触理论,建立了一个弧触头动态接触电阻仿真的理论模型。通过开断过程中的弧触头受力情况分析,得出在八触指自力型弧触头模型中,电流小于2 k A时,可忽略各种电动力的影响,只考虑触指接触压力的影响。在这个假设下,文中首次建立了简化的弧触头动态接触电阻的仿真模型。与大量弧触头模拟烧蚀试验结果对比,文中所提出的弧触头动态接触电阻仿真模型,在弧触头接触行程为15 mm以后,仿真结果与试验结果吻合度较高。

碳纤维发热网络的制备及其在散香服装面料中的应用

在发热面料中探索不同参数的“∞”型和“#”型碳纤维发热网络结构和相应电阻,对研究其发热性能有良好的指导作用。通过改变碳纤维导电结构的外接电压,利用热成像仪观察发热网络温度-时间变化,研究不同结构参数对碳纤维网络发热性能的影响规律。结果表明:相同电压下,增加发热结构单位网格周长,发热能力下降;增加外接电压,则发热结构达到的最高温度随之增加;当单位网格参数相同时,“∞”型发热结构发热速率最快,50 s内可升至最高发热温度并稳定,而“#”型发热结构的发热时间较长,约为125 s,稳定状态下“#”型发热结构能达到较高的发热温度。将发热网络与含温控缓释散香微胶囊的面料复合,制备具有电热温控散香的功能面料,并表征不同网络结构功能面料的散香性能。

Multi-field dynamic modeling and numerical simulation of aluminum alloy resistance spot welding

In order to explore the influence of welding parameters and to investigate the Al alloy (AA) nugget formation process, a comprehensive model involving electrical-thermal-mechanical and metallurgical analysis was established to numerically display the resistance spot welding (RSW) process within multiple fields and understand the AA-RSW physics. A multi-disciplinary finite element method (FEM) framework and a empirical sub-model were built to analyze the affecting factors on weld nugget and the underlying nature of welding physics with dynamic simulation procedure. Specifically, a counter-intuitive phenomenon of the resistance time-variation caused by the transient inverse virtual variation (TIVV) effect was highlighted and analyzed on the basis of welding current and temperature distribution simulation. The empirical model describing the TIVV phenomenon was used for modifying the dynamic resistance simulation during the AA spot welding process. The numerical and experimental results show that the proposed multi-field FEM model agrees with the measured AA welding feature, and the modified dynamic resistance model captures the physics of nugget growth and the electrical-thermal behavior under varying welding current and fluctuating heat input.

Application of Active Damping Control Using Piezoelectric Material in Modeling of a Wind Turbine Blade

On the basic of passive damping control, we do modeling and simulating in another approach to improve the vibration alleviating effect, the piezoelectric layer damping （PLD）, which is called active control. The piezoelectric damping patches are under control of PID controller （matlab simulating） in voltage defference. Here, we use the software PRO/ENGINEER to design and model a wind turbine blade before using COMSOL to simulate the dynamic motion of the wind turbine blade and its interaction with aerodynamic force of wind in finite element method. Some different models are built-- the original turbine blade and the turbine blade with damping patches on different location and quantity. Then, according to the simulation results, we compare the effects of passive and active damping control, also the effect of patches locations and quantities under different wind speed. This research can provide a direction for future study about ways to decrease vibration of turbine blades.

高温超导电缆通流测试系统干扰因子分析与滤除

本文根据高温超导电缆测试系统的回路参数,给出测试系统干扰因子的分析及滤除方法。基于传热微分方程,并利用Comsol仿真,在Labview中完成干扰因子的滤除。结果显示误差仅有2.6%,表明该方法的极具可行性,可以为超导电缆测试过程中的失超判断提供分析和滤除方法,保证失超曲线清晰有效。

Simulation of inter atrial block based on a human atrial model

Inter atrial block(IAB) is a prevailing cardiac conduction abnormality that is under-recognized in clinical practice. IAB has strong association with atrial arrhythmia, left atrial enlargement, and electromechanical discordance, increasing the risk of atrial fibrillation(AF) and myocardial ischemia. IAB was generally believed to be caused by impaired conduction along the Bachmann bundle(BB). However, there are three other conduction pathways, including the fibers posteriorly in the vicinity of the right pulmonary veins(VRPV), transseptal fibers in the fossa ovalis(FO), and muscular bundles on the inferior atrial surface near the coronary sinus(CS). We hypothesized that the importance of BB on IAB might have been overestimated. To test this hypothesis, various combinations of conduction pathway blocks were simulated based on a realistic human atrial model to investigate their effects on the index of clinical diagnosis standard of IAB using a simulated 12-lead electrocardiogram(ECG). Firstly, the results showed that the BB block alone could not generate typical P wave morphology of IAB, and that the combination of BB and VRPV pathway block played important roles in the occurrence of IAB. Secondly, although single FO and CS pathways play subordinate roles in inter atrial conduction, their combination with BB and VRPV block could also produce severe IAB. In summary, this simulation study has demonstrated that the combinations of different inter atrial conduction pathways, rather than BB alone, resulted in ECG morphology of IAB. Attention needs to be paid to this in future pathophysiological and clinical studies of IAB.

Simulation and study on mitigation measures of frequent subsynchronous oscillation with low amplitude at multi-power plants

Subsynchronous oscillation (SSO) with low amplitude that exceeds cumulative fatigue threshold of the generator shaft frequently could significantly reduce the shaft's service life, which is a new SSO problem that emerges in recent years. According to the real recording oscillograph, the basic reason for frequently over-threshold SSO with low amplitude at multi-power plants was analyzed based on Hulunbuir League system. The sensitivities of the electrical damping to the main electrical parameters in the contributing loop of subsynchronous torsional interaction were calculated. Based on the sensitivities, a simulation method was presented, which was used to excite the same oscillation as the actual case by exerting disturbance on the firing angle. The limitation of wide-band and narrow-band supplementary subsynchronous damping controller (SSDC) for mitigating this kind of SSO was analyzed based on the electromagnetic transient simulation model of Hulunbuir League system. The difference of supplementary excitation damping controller (SEDC) and parallel-form FACTS connected to the generator terminal was compared from the aspects of response time and the ability of damping torque supplying. The analysis indicates that their response time is similar but FACTS has stronger ability of damping torque supplying than SEDC. Time-domain simulation method was used to compare the mitigation effects of SEDC, static var compensator (SVC) and static synchronous compensator (STATCOM). Considering the mitigation effect, the floor space limit of the power plant and so on, STATCOM was considered as the best mitigation measure. A control strategy of cascaded STATCOM for engineering application was presented and the capacity for SSO mitigation as well as output characteristics was analyzed. The analysis indicates that STATCOM using the proposed control strategy has better mitigation effect and output characteristics with smaller capacity.