系统电磁脉冲综合环境中导线响应的计算

采用时域有限差分法(FDTD)、粒子模拟(PIC)方法和Holland细线算法,对圆柱腔体内带负载导线的系统电磁脉冲(SGEMP)综合环境响应进行了模拟。计算结果表明:导线负载上的响应电流从大到小依次由透射X射线、SGEMP场和前向电子产生;透射X射线和前向电子产生的响应电流极性相反;SGEMP场在导线负载上响应电流的极性与场分布有关;3种环境在负载上的综合响应中透射X射线的响应最大。对于腔体内的导线来说,SGEMP综合环境防护时透射X射线是重点考虑的因素。     

A class of hierarchical queueing networks and their analysis

Queueing networks are an adequate model type for the analysis of complex system behavior. Most of the more realistic models are rather complex and do not fall into the easy solvable class of product form networks. Those models have to be analyzed by numerical solution of the underlying Markov chain and/or approximation techniques including simulation. In this paper a class of hierarchically structured queueing networks is considered and it is shown that the hierarchical model structure is directly reflected in the state space and the generator matrix of the underlying Markov chain. Iterative solution techniques for stationary and transient analysis can be modified to make use of the model structure and allow an efficient numerical analysis of large, up to now not solvable queueing networks.     

垂向一维均质土壤水分运动在蒸发条件下的运用

本文以新疆乌拉泊尔均衡场，新疆化肥厂试验站及昌吉地下水综合试验场资料求得的非饱和土壤水分特征曲线、水力传导度和土壤扩散率为依据，建立了适合乌鲁本齐地区非饱和土壤水分运动在蒸发条件下运用的数学模型．并用实测资料进行了验证．数值模拟结果与常观实测值有着良好的一致性，可应用于今后试验场在蒸发条件下土壤水动态的预报．     

Experimental investigations into vortex flow in a straight,annular section channel

Results of experimental velocity measurements in air at several cross-sections along a straight annular section channel comparable to a hydraulic machine admission duct are presented. The flow analysis focuses on the axial and tangential velocity components and their modification with changes in the intensity of swirl along the channel. Particular prominence is given to an anomalous flow, the ‘dead water core’, occurring at the greatest swirl intensities. An earlier method of evaluating the core size of this anomalous flow on the basis of a vortex-type schematization is tested; Strscheletzky's method is also analysed. Finally a definition of the dead water core dimensions based on the axial velocity component distribution is proposed     

Transient solution for a finite capacity M/G a,b /1 queueing system with vacations to the server

In this paper we consider a single server queueing system with Poisson input, general service and a waiting room that allows only a maximum of b customers to wait at any time. A minimum of a customers are required to start a service and the server goes for a vacation whenever he finds less than a customers in the waiting room after a service. If the server returns from a vacation to find less than a customers waiting, he begins another vacation immediately. Using the theory of regenerative processes we derive expressions for the time dependent system size probabilities at arbitrary epochs.     

电力电子化电力系统稳定的问题及挑战:以暂态稳定比较为例

随着电力电子技术的进步和环境保护对清洁能源的要求,以同步发电机为主的传统电力系统正向着多样化电力电子装备为主的电力系统转变,由此电力系统正面临着百年来未有之大变局.近年来,国内外不断报道出以电力电子装备为主的新能源基地和传统高压直流等机理不明的电力事故,严重威胁了电力系统安全稳定运行.针对上述问题,本文首先介绍传统电力系统暂态稳定分析的主要方法,接着分析了典型故障场景下简单电力电子化电力系统的动力学行为,并建立了同时包含电力电子设备与传统同步机的多机耦合系统模型,最后总结了电力电子化电力系统的非线性、多时标、复杂性的本质特点,归纳其暂态稳定的基本问题与挑战以及对未来研究方向的展望,希望引起复杂系统和统计物理背景的研究人员的广泛兴趣.     

胆绿素二甲酯金属锌配合物超快激发态动力学研究

胆绿素(BV)及其二甲酯(BVE)是一种生物内源色素,他们在溶液中具有极弱的荧光,量子产率小于0.01%。然而,随着锌离子的加入,情况发生了变化. BVE-Zn²⁺配合物的荧光强度大大增强,荧光QY可提高到∽5%. 本文研究了BVE-Zn²⁺络合物在乙醇、正丙醇和二甲基亚砜溶液中的超快激发态动力学,以揭示其荧光增强的机理. 结果表明,BVE能与锌离子在溶液中形成1:1的稳定配合物,BVE分子结构在复合物中较为刚性,能量上更稳定. 利用皮秒时间分辨荧光光谱和飞秒瞬态吸收光谱技术,发现BVE-Zn²⁺配合物在二甲基亚砜中具有较小的非辐射速率常数,这是其高荧光量子产率关键原因.     

The dual role of multiple-transistor charge sharing collection in single-event transients

As technologies scale down in size, multiple-transistors being affected by a single ion has become a universal phenomenon, and some new effects are present in single event transients (SETs) due to the charge sharing collection of the adjacent multiple-transistors. In this paper, not only the off-state p-channel metal-oxide semiconductor field-effect transistor (PMOS FET), but also the on-state PMOS is struck by a heavy-ion in the two-transistor inverter chain, due to the charge sharing collection and the electrical interaction. The SET induced by striking the off-state PMOS is efficiently mitigated by the pulse quenching effect, but the SET induced by striking the on-state PMOS becomes dominant. It is indicated in this study that in the advanced technologies, the SET will no longer just be induced by an ion striking the off-state transistor, and the SET sensitive region will no longer just surround the off-state transistor either, as it is in the older technologies. We also discuss this issue in a three-transistor inverter in depth, and the study illustrates that the three-transistor inverter is still a better replacement for spaceborne integrated circuit design in advanced technologies.     

Prediction of Heat Conduction with Phase-change Effects during Cooling Stage of Injection Molding of High-density Polyethylene: Approximate Integral Approach

Phase-change problems, also known as the “Stefan problems” or “moving-boundary problems,” are practically significant in modern technological and engineering fields. Injection molding, one of the most widely used polymer processing techniques, can be divided into three stages: filling, packing, and cooling. The cooling stage, which accounts for over three fourths of total molding cycles, greatly affects both productivity and quality of the molded articles. In this work, an approximate integral method was adopted to predict the transient heat conduction with phase-change effects during the cooling stage of injection molding of crystalline polymers. Experiments were conducted to compare with the calculated results, and reasonable agreement was obtained. It was concluded that the present modeling makes good predictions for the cooling stage of injection molding of crystalline polymers, which may be applicable to further studies on the microstructure evolutions during injection molding process as well as the optimal designs in industrial applications.     

Hyperbranched Polylysine: A Versatile,Biodegradable Transfection Agent for the Production of Recombinant Proteins by Transient Gene Expression and the Transfection of Primary Cells

The feasibility of a new transfection agent, HBPL, for the production of recombinant IgG antibody via TGE as well as for the transfection of primary cells is studied. Under the conditions investigated, transfection of CHO‐DG44 cells using HBPL results in IgG yields that are comparable to those obtained with PEI. In experiments with CHO‐K1 cells and MEFs the use of HPBL allows to achieve transfection efficiencies comparable to or better than those obtained with PEI or Fugene®. HBPL‐mediated transfection does not require complex pre‐formation, works well in serum‐containing media and is biodegradable, which may prevent cumulative cytotoxicity and facilitates downstream processing.