计算流管声场的三维有限元数值模型

发展了一种三维有限元数值模型和计算方法来对矩形流管声场进行整体的计算.与以往的二维方法相比,此种数值方法不仅全面反映了矩形流管内声波的传播情况,而且提高了网格精度,从而大大扩展了对铺设有声衬的流管的计算领域.结果表明,该数值模型是有效和准确的,与其它方法和文献的计算结果吻合得非常好.同时,在大大增加计算量的同时,也对程序代码进行了优化工作,提高了计算效率.     

Conductance studies of NaBPh4, NBu4I, NaI, NaCl, NaBr, NaClO4 and the limiting ionic conductance in water + propan-1-ol mixtures at 298.15 K

The electrical conductivities of NaBPh₄, NBu₄I, NaI, NaCl, NaBr and NaClO₄ have been studied in the mixtures of propan-1-ol with water. The obtained results were analysed using the Fuoss–Justice equation. The individual limiting ionic conductivities of Na⁺, NBu₄⁺, BPh₄⁻, I⁻, Cl⁻, Br⁻, ClO₄⁻ ions have been determined using the Fuoss–Hirsch assumption. The dependencies of the limiting molar conductances Λ_o and Walden products Λ_oη versus mixed solvent composition have been discussed.     

Effect of magnon–phonon interaction on transverse acoustic phonon excitation at finite temperature

A magnon–phonon interaction model is developed on the basis of two-dimensional square Heisenberg ferromagnetic system. By using Matsubara Green function theory transverse acoustic phonon excitation is studied and transverse acoustic phonon excitation dispersion curves is calculated on the main symmetric point and line in the first Brillouin zone. On line Σ it is found that there is hardening for transverse acoustic phonon on small wave vector zone (nearby point Γ), there is softening for transverse acoustic phonon on the softening zone and there is hardening for transverse acoustic phonon near point M. On line Δ it is found there is no softening and hardening for transverse acoustic phonon. On line Z it is found that there is softening for transverse acoustic phonon on small wave vector zone (nearby point X) and there is hardening for transverse acoustic phonon nearby point M. The influences of various parameters on transverse acoustic phonon excitation are also explored and it is found that the coupling of the magnon–phonon and the spin wave stiffness constant play an important role for the softening of transverse acoustic phonon.     

Application of inertia-induced excitation theory for nonlinear acoustic modes in colloidal plasma equilibrium flow

Application of inertia-induced acoustic excitation theory offers a new resonant excitation source channel of acoustic turbulence in the transonic domain of plasma flow. In bi-ion plasmas like colloidal plasma, two well-defined transonic points exist corresponding to the parent ion and the dust grain-associated acoustic modes. As usual, the modified ion acoustic mode (also known as dust ion-acoustic (DIA) wave) dynamics associated with parent ion inertia is excitable for both nanoscale-and micronscale-sized dust grains. It is found that the so-called (ion) acoustic mode (also known as dust-acoustic (DA) wave) associated with nanoscale dust grain inertia is indeed resonantly excitable through the active role of weak but finite parent ion inertia. It is interestingly conjectured that the same excitation physics, as in the case of normal plasma sound mode, operates through the active inertial role of plasma thermal species. Details of the nonlinear acoustic mode analyses of current interest in transonic domains of such impure plasmas in hydrodynamic flow are presented.      

Nuclear Physics in Norway, 1933–1955

In the late 1940s and the 1950s, Norwegian nuclear scientists, engineers, and administrators were deeply split over their nation’s goals, organization, politics, and tools for research in nuclear physics. One faction was determined to build a nuclear reactor in Norway, while another fiercely opposed the reactor plans and focused on particle accelerators. The first faction comprised scientific entrepreneurs and research technologists, the second academic scientists, most of whom began their research careers in nuclear physics in the 1930s. To understand this conflict, I trace the development of nuclear research in Norway from the early 1930s to the mid-1950s, placing it within an international context. Roland Wittje is working on his habilitation thesis in the History of Science Unit at the University of Regensburg, Germany.     

A comparative analysis of linear,nonlinear and improved nonlinear thermodynamic models of voltage-dependent ion channel kinetics

The linear, nonlinear and improved nonlinear thermodynamic models of the voltage-dependent ion channels were proposed to deduce the exact functional form of the rate constants. In this context, we present a comparative analysis of the linear, nonlinear and improved nonlinear thermodynamic models of voltage-dependent channel kinetics based on the sodium activation experimental data of Cav3.1 channel. We also provide some insight on the assumptions used to derive the thermodynamic models of the channels and show that the improved nonlinear thermodynamic model provides a simple and physically plausible approach to describe the behavior of the voltage-dependent ion channels.     

部分耗尽SOI MOSFET总剂量效应与偏置状态的关系

实验表明SOI MOSFET掩埋氧化层中的总剂量辐射效应与辐射过程中的偏置状态有关. 对诱发背沟道泄漏电流的陷阱电荷进行了研究. 建立一个数值模型来模拟不同偏置下陷进电荷的建立, 它包括辐射产生的载流子复合和俘获的过程. 模拟结果与实验结果相符, 解释了总剂量辐射效应受偏置状态影响的机理.     

介孔分子筛Al-MCM-41的合成与催化异构化性能

采用正硅酸乙酯(TEOS)为硅源,九水硝酸铝为铝源,十六烷基三甲基溴化胺(CTMABr)为模板剂,在室温条件下合成了介孔Al-MCM-41分子筛.通过XRD、N2等温吸附、SEM、FTIR等分析测试手段表征了分子筛的介孔结构和表面性质.结果表明所合成的分子筛有良好的介孔结构和较高的有序度,并且有较高的比表面积(达到816 m2·g-1)和窄的孔径分布.采用程序升温的焙烧方式、凝胶Al/Si比最大范围控制在0.06～0.13有利于合成高度有序的介孔Al-MCM-41分子筛.评价结果表明,所合成的Al-MCM-41分子筛对桥式四氢双环戊二烯(endo-TCD)异构化反应合成挂式异构体exo-TCD及金刚烷具有较高的催化活性和极高的选择性.     

倾斜均质表面上等径水滴聚合过程的可视化实验

对倾斜均匀表面上等直径水滴的聚合过程及特性进行了可视化实验研究,获得了水滴直径和表面倾角等参数对液滴聚合过程中液滴液桥半径、接触角和接触线变化特性的影响,分析了水滴聚合对其运动的影响.实验结果表明:表面倾角越大,下滑的临界半径越小;液滴的直径越大,液滴聚合后越容易下滑;液滴聚合可以加快液滴的运动,使下滑临界半径减小.     

电容温度传感器的实验研究

从液氮温度到水的沸点温度范围内,测量了介质分别为钽,涤纶,陶瓷,玻璃釉和陶瓷独石一体化结构的商用固体电容器的电容量-温度之间的关系.拟合测量结果表明,独石陶瓷电容器在正温度段具有较好的线性响应(-10pF/℃),灵敏度(0.1 ℃)和精确度(标准差为0.016);而涤纶电容器在负温度段的特性较好( 17pF/℃,0.06 ℃和0.01).此外,在约0.5特斯拉的恒定磁场作用下,无论在正或负温度段,上述测得的电容量-温度关系几乎不受影响.因此,本研究对开发抗强电磁场,自加热效应小或导热系数小的低温测温器具有较大的参考价值.