Novel design model for the stator currents subsystem of induction motors

The stator currents subsystem is a vital element of many high-performance induction motor control schemes. While there are several control techniques available for this subsystem, traditional linear controllers are still widely used because of its simplicity and proven effectiveness. However, the traditional simplified design-model lacks important information, necessary for the design of high-performance and robust controllers. In this article a novel design-model intended for linear controller formulation and evaluation is developed. This new mathematical representation captures several elements which are missing in the traditional representation, maintaining at the same time a similar level of simplicity. Along the derivation of this new representation several models of decreasing complexity and comprehensiveness are also presented together with a critical classification. This classification is intended to aid the designer in choosing the appropriate mathematical representation for specific purposes. Finally, the article is accompanied with experimental findings which illustrate the use of the proposed model.     

Optical Properties of Model Moderately Coupled Plasmas

We review our approach to the modelling of optical properties of model moderately coupled plasmas. On the basis of the classical theory of moments the external and internal dynamic conductivities and the reflectivity coefficient of a model hydrogen moderately coupled plasma are determined using all known exact relations and sum rules. The sum rules which are the power frequency moments of the loss function are calculated using the Deutsch effective potential and the hypernetted chain equations. MD simulation data are used and numerical simulations are suggested (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Nucleation kinetics of paracetamol–ethanol solutions from metastable zone widths

A study of the nucleation kinetics for a cooling crystallisation of paracetamol–ethanol solutions in a batch reactor is described in this paper. Metastable zone width (MSZW) experiments were conducted in order to estimate the nucleation kinetics of the system. Measured MSZWs can be affected by numerous process parameters, such as cooling rate, concentration, agitation rate, and working volume. Two theoretical approaches were employed to estimate the nucleation kinetics, the classical mass based approach of Nývlt, and a more recent approach by Kubota, which also considers number density. Both approaches were found to produce similar estimates for the nucleation rates of the paracetamol–ethanol solutions as a function of supersaturation for an assumed nucleus size of 10 μm. The theory of Kubota was found to predict satisfactory estimates for the induction time of the nucleation process from MSZW data. The induction time was observed to be independent of the solution temperature as suggested by Kubota’s theory. This is a novel finding and serves to validate the induction time theory of Kubota. In this investigation, MSZWs were observed to decrease with increased levels of agitation and found to be independent of working volume.     

Transport Coefficients in Dense Plasmas Including Ion‐Ion Structure Factor

Within linear response theory, a general approach to the thermoelectric transport coefficients for fully ionized hydrogen‐type plasma has been given. Different approximations for the collision integral are considered. Particular attention is given to dynamical screening and the ion‐ion structure factor. Results are presented for the electrical conductivity, the thermal conductivity, and the thermopower in the non‐degenerate limit (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Simulation of metastable zone width and induction time for a seeded aqueous solution of potassium sulfate

The metastable zone width (MSZW, ΔT_m) and induction time (t_ind) were determined with computer simulation for seeded batch crystallization of potassium sulfate from aqueous solution. The MSZW and induction time determined with simulation showed the same behavior as experimental values reported in the literature; log (ΔT_m) increased linearly with an increase in log R (R: cooling rate) and t_ind decreases in proportion to (ΔT)⁻ⁿ (ΔT: supercooling, n: nucleation order in the secondary rate expression of B=k_n(ΔT)ⁿ). The secondary nucleation parameters (k_n and n) were deduced both from the simulated MSZW and induction times by using the previously proposed model [J. Cryst. Growth, 2010, 312, 548–554]. The secondary nucleation rate calculated with the deduced parameters was in agreement with that calculated with the parameters input for simulation.     

Variational Average-Atom in Quantum Plasmas (VAAQP) – Recent progress, virial theorem and applications to the equation-of-state of warm dense Be

The Variational Average-Atom in Quantum Plasmas (VAAQP) code is based on a fully variational theory of dense plasmas in equilibrium in which the neutrality of the Wigner-Seitz ion sphere is not required, contrary to the Inferno model. We report on some recent progress in the VAAQP model and numerical code. Three important points of the virial theorem derivation are emphasized and explained. The virial theorem is also used as an important tool allowing us to check the formulas and numerical methods used in the code. Applications of the VAAQP code are shown using as an example the equation-of-state of beryllium in the warm dense matter regime. Comparisons with the Inferno model, and with available experimental data on the principal Hugoniot are also presented.     

Abduction-induction (generalization) processes of elementary majors on figural patterns in algebra

The article deals with issues concerning the abductive-inductive reasoning of 42 preservice elementary majors on patterns that consist of figural and numerical cues. We discuss: ways in which the participants develop generalizations about classes of abstract objects; abductive processes they exhibit which support their induction leading to a generalization; ways they justify their generalizations in the abductive stage, and; the effects of figural and numerical cues in the manner they construct a plausible abductive generalization. Two types of abductions are explored, model-based and manipulative. A proposed abductive-inductive reasoning process for pattern sequences is presented and discussed in the concluding section.     

He-Ne激光诱变选育高产白藜芦醇细胞系

以葡萄皮脱分化组织为最初材料,用根癌农杆菌702菌株感染,通过纸电泳证明胭脂碱合成醇基因的存在,并在无激素培养基上培养5～6代以上,将此组织(MS)作为本次实验的研究对象.用He-Ne激光辐照,对MS进行诱变处理,通过继代选育,得到优良细胞系T₁₂,其特点是:生长迅速,生长周期比对照组(CK)缩短10～15天;生长曲线的稳定期明显延长,白藜芦醇平均产量比MS组提高40%.通过稳定性实验证明T₁₂组遗传性状是可靠的.     

Thomson散射诊断技术的新进展

Thomson散射是一种主动而无干扰地对等离子体进行诊断的方法．它能够以较高的时空分辨率测量等离子体的参数，如电子与离子温度、密度以及等离子体的膨胀速度、电离程度、热流等参数．文章从Thomson散射基本概念出发，介绍了Thomson散射诊断方法在研究激光与等离子体相互作用中的重要意义，并分别介绍了近年来Thomson散射诊断技术的新进展，如对高Z等离子体、两种离子种类的等离子体、多种形态等离子体以及高密度等离子体的研究．文章最后对国内Thomson散射诊断技术的发展状况进行了简述．     

利用飞秒激光等离子体产生的超热电子进行衍射实验的可行性研究

利用高强度超短脉冲激光与铝靶相互作用可以产生高能超热电子,这些超热电子入射到铝单晶上时将发生衍射.对高强度超短脉冲激光产生的超热电子与晶体的相互作用产生衍射及利用这样的衍射进行晶体结构分析的可行性进行了探讨 关键词： 等离子体 超热电子 衍射 晶体