共查询到20条相似文献，搜索用时 671 毫秒
1.
The mechanical dewatering of activated sludge is difficult due to its high compressibility, which can be improved by electroosmosis. In electroosmosis, direct electric field is applied to sludge cake. Based on the conductivity modes of different sludge beds, a model is presented in which sludge cake consists of two series parts in the circuit: a dewatered bed and an undewatered one. The dewatered bed called solid conductor is mainly made up of immovable water and sludge particles. The undewatered bed includes movable water and solid conductor, which are connected in parallel in the circuit. The model describes the variation of water content with time and electric power consumption as a function of water content in sludge cake, and interprets the reason for the variation of electroosmotic dewatering rate. Comparison with the experimental data for electroosmotic dewatering under constant voltage supports the validity of the model. 相似文献
2.
Aharonov-Casher oscillasions of transmission through a mesoscopic ring with a magnetic impurity is investigated. Both spindependent transmission and reflection coefficients of spin-state electrons at zero-temperature are calculated as a function of the textured electric fields and its title angle in the present of spin-flipper scattering. It is found that the spin-exchange interaction can destroy intermittently periodic oscillations of spin-up transmission and reflection coefficients within some small ranges in the adiabatic region of quantum phase. However spin-down transmission and reflection coefficients appear periodic AC oscillations. The calculated results manifest that spindown transmission and reflection coefficients have the same perfect oscillation patterns. In the nonadiabatic region, the behavior of the anomalous AC oscillations are depedent on the difference between the tilt angle of spin and that of texture electric field. 相似文献
3.
In this paper, we summarize some recent activities in the field of metamaterial research at the National University of Singapore （NUS）. Integral equations are applied for electromagnetic modelling of supernatural materials. Some special characteristics of the metamaterials are shown. Moreover, quasi-static Lorentz theory and numerical method （i.e., the method of moments for solving the electric field integral equation） and the transmission line theory are both presented to obtain the effective constitutive relations of metamaterials, respectively. Finally, feasibility of fabricating metamaterials based on analysis of equivalent transmission line model in the microwave spectrum and even higher is also shown and correspondingly some broad-bandwidth and low-loss metamaterial structures are designed and synthesized. 相似文献
4.
To investigate the influence of expansion pretreatment for materials on carbon structure, activated carbons (ACs) were prepared from corncob with/without expansion pretreatment by KOH activation, the structure properties of which were determined based on N 2 adsorption isotherm at 77 K. The results show that the expansion pretreatment for corncobs is beneficial to the preparation of ACs with high surface area. The specific surface area of the AC derived from corncob with expansion pretreatment (AC-1) is 32.5% larger than that without expansion pretreatment (AC-2). Furthermore, to probe the potential application of corncob-based ACs in electric double-layer capacitor (EDLC), the prepared ACs were used as electrode materials to assemble EDLC, and its electrochemical performance was investi- gated. The results indicate that the specific capacitance of AC-1 is 276 F/g at 50 mA/g, which increases by 27% com- pared with that of AC-2 (217 F/g). As electrode materials, AC-1 presents a better electrochemical performance than AC-2, including a higher voltage maintenance ratio and a lower leakage current. 相似文献
5.
There are a large number of wooden-plank wall dwellings, a kind of traditional house with regional characteristics, existing in Chongqing area. We chose a typical house in Chongqing as the subject and measured it during summer to research the situation of the indoor thermal comfort of wooden-plank wall dwellings. Based on the particularity of local residents’ living habit and the characteristics of the local buildings, we analyzed the data of the field measurement and evaluated the thermal environment with APMV. The results show that the indoor thermal comfort of wooden-plank wall dwellings in summer is improved mainly by natural ventilation. 相似文献
6.
The behavior of variable transparency glass is studied, and the response time analyzed and measured aimed at applications to welding goggles. Detection apparatus for goggle testing is involved in the design and development. Charac-teristics of the apparatus are discussed based on experiments. The definition of nominal response time and effective response time are presented based on the analysis and calculation with experimental data. 相似文献
7.
C. W. LIM 《浙江大学学报(A卷英文版)》2010,11(1):34-42
The transverse free vibration of nanobeams subjected to an initial axial tension based on nonlocal stress theory is presented. It considers the effects of nonlocal stress field on the natural frequencies and vibration modes. The effects of a small scale parameter at molecular level unavailable in classical macro-beams are investigated for three different types of boundary conditions： simple supports, clamped supports and elastically-constrained supports. Analytical solutions for transverse deforma- tion and vibration modes are derived. Through numerical examples, effects of the dimensionless nanoscale parameter and pre-tension on natural frequencies are presented and discussed. 相似文献
8.
Magnetic flux density around the weld area was used to reconstruct the current density distribution during resistance spot welding(RSW) of aluminum alloy according to inverse problem theory. A current-magnetic field model was established and the conjugate gradient method was used to solve this model. The results showed that the current density was low at the center of nugget while high on the edge of nugget. Moreover, the welding time of 30ms—60 ms is a key period for nucleation. The current density distribution can reflect whether the weld nugget is formed or splashed, therefore it has the potential to monitor the weld quality of RSW. 相似文献
9.
INTRODUCTION The gymnasium project located in the newcampus of Zhejiang University is a symbol building(Fig.1). The requirements on the functions and theesthetics make it distinguished from a traditionalgymnasium. It is a two-story building with the firstfloor used for field competition and the second floorfor students’ basketball training. The heavy live loadsacting on the second floor and the requirement of 35m unobstructed space challenge the creativity of thestructural enginee… 相似文献
10.
We designed and used a series of activities （named activities to teaching electric field （ATEF）） based on the Physics by Inquiry （PBI） strategy to teaching the electric field concept with university students. We used a concentration factor tool to assess the effectiveness of those activities used during three weeks of instruction. Results indicate that students who had traditional teaching obtained a very tiny gain （less than 1%）; concentration factors indicate that most of their responses fall into a random area, which is not favorable. On the other hand, the experimental group using our activities had greater gains （〉 10%） than the control group. Concentration factors showed that after instruction, students＇ mental models changed toward a favorable pattern about comprehension of electric field concept and Coulomb＇s law. A hypothesis test of two samples indicated that there is a significant difference between both traditional teaching and ATEF based on PBI. 相似文献
11.
得到了计算各向异性非均匀介质电场的有限差分方程,验证了所得差分方程的正确性;得到了各向异性三棱体内外电场与电势的分布,研究了该目标的Rayleigh散射特性;仿真结果表明：外电场极化方向的介电常数明显的影响散射,垂直方向的介电常数影响不大;算法不受目标形状、电磁参数等因素的影响,简单明了,具有良好的通用性。 相似文献
12.
李瑾 《陕西教育学院学报》2014,(5):123-124
直接从点电荷场强公式出发,利用泰勒级数展开法,得出了均匀带电圆盘周围任意点的电场表达式,所得结果在特殊情况下与有关的文献完全一致;定量的给出了圆盘周围电场强度分布矢量图,为平行板电容器研究、有限长带电圆柱电场的研究奠定了理论基础。 相似文献
13.
唯一性定理是解决静电磁场问题的理论依据。课本中给出了静电场唯一性定理的表述形式及其严格证明,对于磁场部分则是点到即止。本文首先给出静磁场唯一性定理的表述形式,对一般情况下和库仑规范条件.＆A=0下的情况均作了证明,得出后者只是一般情况下的一个特例。 相似文献
14.
在经典的单细胞模型基础上提出了一种近似的活细胞模型,用来拟合有初始跨膜电位的细胞。外加电场作用下,引用概率函数分析了细胞膜电穿孔不对称特性,分析了控制电穿孔不对称性的手段是调整电场参变量(电场强度、频率和占空比)。用MATLAB对模型进行仿真,验证了细胞跨膜电位随参数变化的规律。比较细胞上不同区域的膜电位和细胞膜电穿孔阈值电压,得出的结论是:由于细胞膜有初始跨膜电位的存在(如U_0=-70mV),如果合理选取电场的各参数,可以控制细胞膜上形成电穿孔的不对称性。讨论了电穿孔的不对称特性在生物技术和医学领域的应用意义。 相似文献
15.
F M S Lima 《Resonance》2018,23(11):1215-1223
In the presently available literature, one finds distinct results for the electric field at the surface of a charged conducting sphere. In most textbooks, only a simple model is presented in which the electric field leaps from zero (inside the sphere) to a maximum value (just outside the sphere), as follows from Gauss’s law. For points exactly at the surface, the charge surrounded by the Gaussian surface becomes ambiguous, and this law is inconclusive. In this paper, by treating the spherical surface as a series of rings, it is shown that that field evaluates to half the discontinuity mentioned above, a result which agrees with more elaborate microscopic models. 相似文献
16.
均匀带电细圆环是电磁学理论及应用中的基本模型,研究其产生的电场在空间的分布具有重要意义。本文由电势的叠加原理,首先推导出均匀带电细圆环在空间任一点的电势表达式,并用数学软件Mathematic绘出了其电势在空间的分布-等势线的分布;然后由电场强度和电势的关系,得到了空间任一点的电场强度表达式,并进行了数值模拟。 相似文献
17.
方海 《韩山师范学院学报》2007,28(3):55-59
讨论了带电粒子在外电场以及无外电场作用下的漂移运动的物理模型,并且讨论了电流导致导体升温情况下带电粒子的运动,使用Monte Carlo方法对其进行了动画模拟,形象地表现出带电粒子在各种情况下的运动状态． 相似文献
18.
丁斌峰 《廊坊师范学院学报(自然科学版)》2009,9(3):50-52
针对均匀电场作用下介质球周围电场分布情况,建立了二维电场数学模型,采用有限差分法,对场域内的Laplace方程和边界条件进行离散化,得到了均匀电场作用下介质球周围及其内部的电势及电场分布的数值解,并从理论上验证了该数值解的准确性。 相似文献
19.
丁斌峰 《河北职业技术学院学报》2009,(3)
针对均匀电场作用下介质球周围电场分布情况,建立了二维电场数学模型,采用有限差分法,对场域内的Laplace方程和边界条件进行离散化,得到了均匀电场作用下介质球周围及其内部的电势及电场分布的数值解,并从理论上验证了该数值解的准确性。 相似文献
20.
张宁宁 《渭南师范学院学报》2012,(10):48-52
在电四极矩的基础上,写出了静止状态的任意位置放置的平面电四极子的电磁场分布,利用电磁场相对论变换关系,计算了任意方向平面电四极子匀速运动的电磁场分布,并且对其结果进行讨论,表明了其结论是对前人工作的进一步补充,且具有普遍意义. 相似文献