三倍压电压倍增器的性能及其实验

本文阐明了电源通过恒流管激励三倍压电压倍增器,并以实验结果为依据论述了这种电压倍增器的性能,指出了这种倍增器的可用性.实验表明这种电压倍增器的输出电阻比较小,所以它的对电流变化的稳定性比较好.恒流管激励三倍压电压倍增器比电阻激励三倍压电压倍增器的稳定性要好得多.     

聚丙烯酰胺溶液在渗流过程中的流变性实验研究

通过岩心渗流实验,研究了不同相对分子质量、不同质量浓度的聚丙烯酰胺(聚合物)溶液在多孔介质中的渗流特性;根据不同渗流速度下的渗流压力变化,计算了不同聚合物溶液在多孔介质渗流过程的有效粘度;分析了不同质量浓度和相对分子质量的聚合物溶液在多孔介质中的流变性变化。结果表明:在达西渗流速度范围内,聚合物溶液在渗流过程中岩心两端的压差随流量的增加表现出先上升后上翘的趋势;聚合物溶液在多孔介质中的有效粘度随剪切速率的增加先减小后增大;溶液的相对分子质量越大、质量浓度越大,有效粘度越大。     

电功、电功率及生活用电复习指导

【知识要点] 一、电功 卿缪戮释赘班争 用电器在 标有“220 下的功率叫额定功率一只 V’,表示该 若则; 1.电流通过电动机做功时,电能转化为 能;电流通过电灯,灯丝炽热发光时,电能转化 为和能. 2.电流做功的过程,实际上是电能转化为 能量的过程.电流做了多少功,就 有多少电能转化为 3.实验表明,在通电时间相同的情况下,电 压越大,电流越大,电流做功越_;如果 保持电压和电流不变,通电时间越长,电流做功 就越__.所以电流在某段电路上所做的功,等 于这段电路、和的乘 积,写成公式是_. 4.在国际单位制中,电功的单位是_; 常用的单位是,也就是日常…     

压电能量收集器的有限元仿真与分析

压电能量收集是微能量领域的研究热点。为了优化压电能量收集器的设计并提高其输出电压,对压电单晶悬臂梁进行了有限元仿真与分析,包括对压电单晶悬臂梁的最大应力,产生的最大电压,以及压电晶片的长度、基板的材质和压电晶片的粘结位置对输出电压的影响都作了详细的研究。仿真结果表明,有限元方法能为压电能量收集器件的优化设计提供重要的理论指导。     

电阻知识预习

我们知道,电压越大,电路中的电流就越大,灯泡就越亮.同学们思考过这样的问题吗?让电路中的电压相同,将灯泡接在不同的电路里,灯泡亮度会一样吗?在图1所示的实验中,我们改变电路中接入的金属丝的种类,就可以根据灯泡的亮度情况,探究出电路中电流的大小     

强电场电离放电对水稻幼苗生长生物学效应的试验性研究

为了研究强电场电离辐射对水稻种子酶活性的影响,在相同激励电压下,用不同时间辐射国稻6号水稻种子。发现用160V激励电压分别辐射10s、15s、20s、25s、30s、50s的试验组与对照组相比,淀粉酶、过氧化氢酶（CAT）和过氧化物酶（POD）的活性均有明显提高,淀粉酶辐射时间为25s效果最好,而CAT和POD辐射时间为25—30s时效果最佳。实验表明强电场电离辐射能促进水稻幼苗的生长发育和蛋白质合成,并降低活性氧对幼苗的损害。     

这个实验应该这样做——对电功实验的改进

人教版九年教育三年制初级中学物理课本第二册第九章的电功实验是这样做的 (图 1 ) :先通过电动机把砝码提起 ,表明电流能够做功 ;再保持相同的通电时间 ,用变阻器改变电压和电流 ,通过比较不同电压和电流时砝码被提升的高度 ,来说明在相同的时间内 ,电压越大电流越大 ,电流做功越多。图 2　　由于通过电动机的电流与电动机两端的电压是同时变大或变小的 ,因而教材中的这个实验不能很好地说明 :①在通电时间相同 ,电流相同时 ,电压越大 ,电流做功越多 ;②在通电时间相同 ,电压相同时 ,电流越大 ,电流做功越多。因此 ,这个实验应作改进。　　…     

电化学合成聚苯胺电致变色膜

作为一种导电聚合物材料，聚苯胺电致变色膜具有广阔的市场应用前景。本文从学生开发实验的要求出发，以导电玻璃为电极，讨论了电化学方法合成聚苯胺时电压、聚合时间及酸浓度等因素对聚苯胺导电膜电致变色性的影响，将较为复杂的生产工艺以简单直观的学生实验表示出来，对学生实践能力的培养具有一定的意义。     

探究同种物质的质量与体积的关系

1.提出问题同种物质组成的物体体积越大,那质量随体积变化有什么样的具体关系?2.猜想与假设同一种物质的质量和它的体积成正比.3.制订计划与设计实验取体积不同的水,分别测出它们的质量和体积进行探究.4.进行实验及收集证据(1)选取实验     

电压互感器二次回路降压与电能计量的教学探讨

电机教学中.由于电压互感器二次回路压降直接影响电能量计量的准确性.严重时会危及电力系统的稳定运行,因此本文从分析电压互感器二次压降的形成机理入手,并提出最为合理的二次压降治理方案,作为教学应用时参考.     

Complete Charging for Piezoelectric Energy Harvesting System

Under an in-phase assumption, the complete charging for an energy harvesting system is studied, whichconsists of a piezoelectric energy harvester （PEH）, a bridge rectifier, a filter capacitor, a switch, a controller and arechargeable battery. For the transient charging, the results indicate that the voltage across the filter capacitor increasesas the charging proceeds, which is consistent with that reported in the literature. However, a new finding shows thatthe charging rate and energy harvesting efficiency decrease over time after their respective peak values are acquired.For the steady-state charging, the results reveal that the energy harvesting efficiency can be adjusted by altering thecritical charging voltage that controls the transition of the system. The optimal energy harvesting efficiency is limitedby the optimal efficiency of the transient charging. Finally, the relationship between the critical charging voltage andthe equivalent resistance of the controller and rechargeable battery is established explicitly.     

Mechanics of dielectric elastomers: materials,structures, and devices

Dielectric elastomers (DEs) respond to applied electric voltage with a surprisingly large deformation, showing a promising capability to generate actuation in mimicking natural muscles. A theoretical foundation of the mechanics of DEs is of crucial importance in designing DE-based structures and devices. In this review, we survey some recent theoretical and numerical efforts in exploring several aspects of electroactive materials, with emphases on the governing equations of electromechanical coupling, constitutive laws, viscoelastic behaviors, electromechanical instability as well as actuation applications. An overview of analytical models is provided based on the representative approach of non-equilibrium thermodynamics, with computational analyses being required in more generalized situations such as irregular shape, complex configuration, and time-dependent deformation. Theoretical efforts have been devoted to enhancing the working limits of DE actuators by avoiding electromechanical instability as well as electric breakdown, and pre-strains are shown to effectively avoid the two failure modes. These studies lay a solid foundation to facilitate the use of DE materials, structures, and devices in a wide range of applications such as biomedical devices, adaptive systems, robotics, energy harvesting, etc.     

A new energy harvester using a piezoelectric and suspension electromagnetic mechanism

This study presents a new design of a piezoelectric-electromagnetic energy harvester to enlarge the frequency bandwidth and obtain a larger energy output. This harvester consists of a primary piezoelectric energy harvesting device, in which a suspension electromagnetic component is added. A coupling mathematical model of the two independent energy harvesting techniques was established. Numerical results show that the piezoelectric-electromagnetic energy harvester has three times the bandwidth and higher power output in comparison with the corresponding stand-alone, single harvesting mode devices. The finite element models of the piezoelectric and electromagnetic systems were developed, respectively. A finite element analysis was performed. Experiments were carried out to verify the validity of the numerical simulation and the finite element results. It shows that the power output and the peak frequency obtained from the numerical analysis and the finite element simulation are in good agreement with the experimental results. This study provides a promising method to broaden the frequency bandwidth and in- crease the energy harvesting power output for energy harvesters.     

Energy harvesting with a slotted-cymbal transducer

A cymbal transducer is made up of a piezoceramic disk sandwiched between two dome-shaped metal endcaps. High circumferential stresses caused by flexural motion of the metal endcaps can induce the loss of mechanical input energy. Finite element analysis shows that the radial slots fabricated in metal endcaps can release the circumferential stresses, and reduce the loss of mechanical input energy that could be converted into electrical energy. In this letter, the performance of a slotted-cymbal transducer in energy harvesting was tested. The results show that the output voltage and power of the cymbal are improved. A maximum output power of around 16 mW could be harvested from a cymbal with 18 cone radial slots across a 500 kΩ resistive load, which is approximately 0.6 times more than that of the original cymbal transducer.     

Energy harvesting from pavement via polyvinylidene fluoride: hybrid piezo-pyroelectric effects

In the USA, there are over 4 million miles (6 million km) of roadways and more than 250 million registered vehicles. Energy lost in the pavement system due to traffic-induced vibration and deformation is enormous. If effectively harvested, such energy can serve as an alternative sustainable energy source that can be easily integrated into the transportation system. It is well known that most piezoelectric materials are also pyroelectric materials, which convert temperature change into electricity. However, the potential of polyvinylidene fluoride (PVDF) as a hybrid piezo-pyroelectric energy harvester has been seldom studied. The uniqueness of this study lies in that the electrical responses of PVDF under coupled mechanical and thermal stimulations are investigated. Through a series of well controlled experiments, it is found that there exists an interesting coupling phenomenon between piezoelectric and pyroelectric effects of PVDF: the voltage generated by simultaneous mechanical and thermal stimulations is the algebraic sum of voltages generated by separate stimulations. This means that there is neither strengthening nor weakening coupling effect when the piezoelectric and pyroelectric phenomena are coupled. This also makes the modeling process of the hybrid piezoelectric and pyroelectric effect straightforward. An estimation of power generation through piezoelectric and pyroelectric effect is conducted, and the overall effects of temperature on hybrid piezo-pyroelectric energy harvesting are discussed.     

适合学校实验室使用的节能型稳压器设计

学校实验室精密仪器设备一般都配备稳压器,以保证仪器的正常使用,然而稳压器的能源损耗是一大浪费。如何降低稳压器的能源损耗,让市电在安全电压范围内时,使稳压器自动脱离电源,将市电直接供给负载,消除稳压器自身损耗;负载为零时,也使稳压器自动脱离电源,消除其空载损耗,让稳压器的能源损耗降至最低,又能发挥稳压器应有的作用,经试制,达到了设计功能。     

一种高压击穿自动切换低压保持的放电管老化电路设计

对放电管两端施加电压直至击穿后,再以规定电流保持一段时间的放电状态,是其出厂前必经的老化处理过程。不同型号的放电管有着不一样的击穿电压和放电电流,采用直接高压击穿后放电维持的传统方法需消耗较大的能量。为此设计应用了一种高压击穿后能自动切换为低压老化的电路,有效地解决了传统老化方法中电能消耗过大的问题。     

高压隔离采集电路的设计

分析了霍尔电压传感器在高压隔离采集中的使用方法、工作原理、设计参数的计算以及运算放大器的选用原则。该方案可应用在直流高压采集和交流高压采集场合,考虑在恶劣环境中使用的稳定性和可靠性,在电路设计中增加了调零电路和补偿电路,可将误差降到最小,以保证精度的要求,并能根据使用场合的不同,按需要取舍。     

EDA仿真实验与放大电路理论公式关系的初步探讨

文章通过用两种模拟电子技术教科书中所用的公式求解同一共射放大电路的电压增益,结果两者居然出现不同;再用仿真实验的方法求证计算其电压增益,而结果与用其中一种的结果相吻合,因此提出一个大胆推测：误差比较大的模拟电子技术中用公式rbe=rbb＋（1＋β）Ur/IEQ,在某种条件下rbb=300Ω存在误差。并探讨通过等效公式的推导,对公式中体电阻rbb的经验数据提出一个修正的式子;     

锡氧化物电热膜的过电压耐量问题

从电热转换元件的电毁现象出发。利用膜材料电性能的各向同性性质,建立了一维晶粒列模型,给出了晶粒列模型的平衡态能带图和带尾态分布以及在外加电压下的非平衡态能带图,并分析了自由电子在越过晶问势垒时受到的加速和散射的情况．通过导出数学模型,得出了电子柬的电毁能量应大于等于晶体结合能的结论,并得到了晶粒子大小不同的膜材料有不同的过电压耐量的比值,为元件的工艺设计、可靠性研究和过电压保护器件研究提供了参考．