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简述了涡电流加热的实验原理,并设计了涡电流加热实验仪.该实验仪利用给带铁芯的线圈通电产生的磁场,通过磁场变化产生涡电流,同时释放出热量达到涡电流加热的目的.比较了几种金属的涡电流加热与同种金属在不同电源频率下的涡电流加热的效果. 相似文献
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提出了一种同轴电缆结构的霍尔效应装置.若中心导体通电流,则在通电的导体壳内外表面之间产生霍尔电势差.讨论了导体壳电势差与中心导体的电流强度、导体壳的电流强度以及导体壳结构之间的关系,发现导体壳很薄时霍尔电势差最大. 相似文献
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磁化水具有比普通水更小的簇合分子,具有硬度、pH值、含氧浓度均增加的性质.采用傅立叶变换红外光谱技术,测量了大豆与玉米实验组与空白组的叶绿体的红外光谱,发现两者在酰氨键的振动吸峰处存在一定的差异,实验组的吸收明显强于对照组,说明磁化水对作物的生长发育有一定影响,具有一定的生物效应. 相似文献
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向列相液晶电光特性研究 总被引:1,自引:0,他引:1
通过对液晶电光效应这一新开设的大学物理实验的介绍,建立棒状分子模型,从理论上分析当液晶盒通电后其自由能变化.利用实验手段研究了液晶在电场中的相关特性. 相似文献
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Herein, the dynamic pull-in instability of cantilever nanoactuator fabricated from conductive cylindrical nanowire with circular cross-section is studied under the presence of Casimir force. The Gurtin–Murdoch surface elasticity in combination with the couple stress theory is employed to incorporate the coupled effects of surface energy and size phenomenon. Using Green–Lagrange strain, the higher order surface stress components are incorporated in the governing equation. The Dirichlet mode is considered and an asymptotic solution, based on the path integral approach, is applied to consider the effect of the Casimir attraction. Furthermore, the influence of structural damping is considered in the model. The nonlinear governing equation is solved using analytical reduced order method (ROM). The effects of various parameters on the dynamic pull-in parameters, phase planes and stability threshold of the actuator are demonstrated. 相似文献
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A general model for nano-cantilever switches with consideration of surface stress, nonlinear curvature, the location and length of the fixed electrode is developed. Some representative cantilever switch architectures are incorporated into this model. The governing equation is derived by using Hamilton principal and solved numerical. Results show that the influence of nonlinear curvature and surface effect on the pull-in instability and free vibration is significant for a switch with a large gap-length ratio and a short fixed electrode (the length of the fixed electrode is smaller than that of the cantilever nanobeam). The length and position of the fixed electrode have a significant effect on the pull-in parameters. 相似文献
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Effect of driving frequency on electron heating in capacitively coupled RF argon glow discharges at low pressure
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A one-dimensional(1D) fluid model on capacitively coupled radio frequency(RF) argon glow discharge between parallel-plates electrodes at low pressure is established to test the effect of the driving frequency on electron heating. The model is solved numerically by a finite difference method. The numerical results show that the discharge process may be divided into three stages: the growing rapidly stage, the growing slowly stage, and the steady stage. In the steady stage,the maximal electron density increases as the driving frequency increases. The results show that the discharge region has three parts: the powered electrode sheath region, the bulk plasma region and the grounded electrode sheath region. In the growing rapidly stage(at 18 μs), the results of the cycle-averaged electric field, electron temperature, electron density, and electric potentials for the driving frequencies of 3.39, 6.78, 13.56, and 27.12 MHz are compared, respectively. Furthermore,the results of cycle-averaged electron pressure cooling, electron ohmic heating, electron heating, and electron energy loss for the driving frequencies of 3.39, 6.78, 13.56, and 27.12 MHz are discussed, respectively. It is also found that the effect of the cycle-averaged electron pressure cooling on the electrons is to "cool" the electrons; the effect of the electron ohmic heating on the electrons is always to "heat" the electrons; the effect of the cycle-averaged electron ohmic heating on the electrons is stronger than the effect of the cycle-averaged electron pressure cooling on the electrons in the discharge region except in the regions near the electrodes. Therefore, the effect of the cycle-averaged electron heating on the electrons is to "heat" the electrons in the discharge region except in the regions near the electrodes. However, in the regions near the electrodes, the effect of the cycle-averaged electron heating on the electron is to "cool" the electrons. Finally, the space distributions of the electron pressure cooling the electron ohmic heating and the electron heating at 1/4 T, 2/4 T, 3/4 T, and 4/4 T in one RF-cycle are presented and compared. 相似文献
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In this article, an analytical method for calculating pull-in voltage is proposed. This method can accurately predict pull-in voltage of clamped-free, clamped-clamped and curved micro- and nano-beams. In this study, mid-plane stretching, axial stress, initial deformation and the effect of size are taken into account. To achieve this goal, governing equation of beam based on modified couple stress theory was first derived and then transformed to a single degree of freedom (D.O.F) model by Galerkin method. In this model, electrostatic force appears in integral form which is approximated to non-integral form employing Genetic Algorithm. This single degree of freedom model provides means for obtaining critical deflection of beam and is used to find the general closed-form expression for pull-in voltage. The validation of the method was carried out by comparing the results with the existing literature. 相似文献
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The effect of thermal environment on boiling heat transfer performance in a section of a horizontal tube bundle was investigated using R-113 as the working fluid. The in-line tube bundle has five columns and 27 rows with a pitch-to-diameter ratio of 1.3. Heal transfer coefficients obtained from the instrumented tube in the tube bundle with only one tube heated while the other tubes remained unhealed and with all the lubes in the bundle heated are reported for a range of heat flux, pressure, mass flow rate, and quality. The results showed that heat transfer coefficient of a tube in a heated bundle is slightly higher than that in an unhealed bundle, with the variation of heat transfer coefficient decreasing as heat flux, mass flow rate, or pressure increased. It was also found that higher quality would tend to improve the heat transfer. However, the effect of quality disappeared as heat flux, mass flow rate, and pressure increased. Based on the experimental data, the mechanism of the heat transfer augment due to thermal environment was analyzed. It was proposed that fluid agitation and thin liquid film formation are two main factors for a heated bundle to have better transfer performance than an unhealed bundle, 相似文献
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M. V. Cheremisin 《Journal of Experimental and Theoretical Physics》2001,92(2):357-360
The standard ohmic measurements by means of two extra leads contain an additional thermal correction to resistance. The current results in heating (cooling) at the first (second) sample contact because of the Peltier effect. The contact temperatures are different. The measured voltage is the sum of the ohmic voltage swing and the Peltier-effect-induced thermoelectromotive force that is linear in the current. As a result, the thermal correction to the resistance measured exists as I→0. The correction could be comparable with the ohmic resistance. Above some critical frequency depending on thermal inertial effects, the thermal correction disappears. 相似文献
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Takashi Ueda Yoshihiro WakimuraTatsuaki Furumoto Akira HosokawaRyutaro Tanaka 《Optics and Lasers in Engineering》2011,49(1):137-144
The purpose of this research is to establish the technique of laser flattening and to consider the fundamental mechanism. The thermal stress produced by heating with a laser beam is used to make a flat sheet from a sheet metal of protruded distortion. Three kinds of protrusions are chosen as the typical protruded distortion; point protrusion, line protrusion and face protrusion. For point protrusion, laser irradiation along the circular path is effective when the height of protrusion is large, and the laser irradiation along the radial path is effective when it is small. For line protrusion, laser beam is irradiated along the short straight path whose direction is normal to the centerline of the protrusion. For face protrusion, the height decreases from 1-0.1 mm by the laser irradiation along the circular path. The residual stress at the convex surface of a point protrusion on the sheet metal changes from a large compressive stress to a small tensile stress by the laser irradiation. 相似文献
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B.X. Li Y.P. Lu L.H. Liu H.P. Tan 《Journal of Quantitative Spectroscopy & Radiative Transfer》2005,92(1):51-59
For the purpose of energy conservation and uniform heating of object surface, a gas-fired porous radiant burner with a bundle of reflecting tubes is developed. A physical model is developed to simulate the directional radiative behavior of this heating device, in which the Monte Carlo method based on the concept of radiation distribution factor is used to compute the directional radiative behavior. The effects of relating parameters on the directional behavior of radiative heating and the heating efficiency are analyzed. With the increase of the length-to-radius ratio of tube, the radiation heating efficiency decreases, but the radiation energy incident on the object surface is more collimated. The radiation heating efficiency increases with the specular reflectivity. With the increase in length of tube segment with specular reflective surface, the radiation heating efficiency increases, but the extent of concentration and collimation of radiative energy decreases. For real design of the heating device, some trade-offs are needed to balance the radiation heating efficiency and the uniformity of radiative heating of object surface. 相似文献
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基于一维应力松弛模型和粘弹性本构关系,对1.06μm连续激光照射下K9玻璃板中的温升和应力作了计算,结果表明,由于应力松弛效应,激光停照后的冷却过程中产生的残余拉伸应力可达到玻璃的拉伸断裂强度阈值,而激光加热期间的最大压缩应力却小于压缩断裂强度要求。对3mm厚的K9玻璃板,由应力松弛引起破坏所要求的激光参数为946kWm-2作用0.2s,因而应力松弛可能为1.06 μm连续激光大光斑照射下K9玻璃窗口损伤的主要模式。 相似文献