Control of the quality of polymer products in continuous reactors: comparison of performance of state estimators with and without updating of parameters

In the paper the control of the product quality in polymerization reactors is analysed in the presence of persistent perturbations (unmodeled disturbances, modeling errors), as met in industrial reactors. The free radical polymerization of methyl-methacrylate in a continuous stirred tank reactor is studied. It is shown that state estimators (Extended Kalman Filters) with constant parameters cannot give offset free performance. Criteria for the selection of a set of parameters to be updated as additional states in the filter and to evaluate their effectiveness in opposing the action of realistic perturbations are given by an analysis of the linearized model of the system. Performance of different types of estimators, including one and two-time scale filters, with and without updating of parameters, is analysed by simulation on the full order process and the predictions made by previous analysis are confirmed. In the most common case of presence of perturbations affecting the energy balance and the concentration of initiator in the reactor, offset free control of the molecular weight of the product can be achieved by means of a filter which is based only on measurements of temperature and conversion and makes an update of two parameters. In the case that also the kinetic model of the polymerization reaction is affected by errors, a two-time scale filter, which makes use also of Molecular Weight values and updates three parameters, becomes necessary to obtain offset free performance.     

再谈冶金学中使用国际单位制的若干问题

讨论了近年来在冶金书刊中作为国际单位制推行的质量分数和传统的质量百分浓度的关系，指明了出现计算错误的可能性，并联系热力学函数的标准状态进行了分析。也提出了冶金学中使用国际单位制目前还存在的若干问题。     

Chemical States of Lanthanum in Carbonized La2O3-Mo Thermionic Cathode Materials

The chemical reaction between lanthanum oxide and molybdenum carbide was studied by thermodynamic calcu-lation, thermal analysis and in-situ X-ray Photoelectron Spectroscopy. The theoretical results show that at the environment allowing for the evaporation of lanthanum, such as in high vacuum, La2O3 in the La2O3-Mo materials can be reduced to metallic lanthanum by molybdenum carbide (Mo2C). To confirm the conclusion, many analysis methods such as XRD, SPS, and TG-DTA were taken. The experimental results show that the chemical state of lanthanum changes during heat-ing. It was proved, for the first time, that reacted metallic lanthanum appears at the surface of this kind of material at high temperature.     

计及PMU的混合非线性状态估计新方法

提出一种将同步相量测量单元（PMU）的直接电压相量量测变换为间接支路电流量测，并与监控与数据采集（SCADA）量测量一起进行混合迭代的非线性状态估计方法。对构造等效电流修正量而带来的间接量测误差进行了详细和定量的分析，并对该混合估计算法的精度进行了定性分析和定量计算。理论分析和算例表明，该方法可以获得较高的估计精度，在收敛次数和滤波效果上也有所改进。     

On‐Line Detection Of State‐Of‐Charge In Lead Acid Battery Using Radial Basis Function Neural Network

To realize a stable supply of electric power in an automobile, an accurate and reliable detection method of SOC (state‐of‐charge) in a lead acid battery is required. However the dynamics of the battery is very complicated. The characteristics of the battery greatly change due to its degradation. Moreover a automobile has many driving patterns, which are unknown beforehand. Thus it is not easy to detect the SOC analytically. In this paper, to overcome this problem, a new on‐line SOC detection method with a radial basis function neural network is proposed. In order to increase the detection accuracy of degraded batteries, physical values related to the degradation degree are used as input signal in the neural network. The detection accuracies for different sized batteries and various degradation states are investigated.     

Vapor-liquid equilibrium and volumetric properties calculations for solutions in the supercritical carbon dioxide

The calculations of gas solubilities in supercritical solvents require equations of state remaining accurate in the critical range, which are difficult to obtain with classical models. In this work, the Helmholtz energy of a mixture is considered as the sum of the Helmholtz energies of pure components taken at a constant packing fraction and of a residual term which may have the form of a RedlichKister, Van Laar, NRTL, UNIQUAC, or UNIFAC function. Thus it is possible to assign to a given component an equation of state whose form is different from that of the others. This model has been applied to binary systems containing supercritical carbon dioxide. The results are improved with respect to those obtained with the classical model for vapor-liquid equilibria and for volumetric properties.     

富水电厂机组在线监测及状态检修

介绍了在富水电厂实施状态检修管理体制的情况以及与之相关的在线监测技术。     

What the small Rubik’s cube taught me about data structures, information theory, and randomisation

This article discusses observations made when the state space of the 2 × 2 × 2 Rubik’s cube was constructed with various programs based on various data structures, gives theoretical explanations for the observations, and uses them to develop more memory-efficient data structures. The cube has 3,674,160 reachable states. The fastest program runs in 20 s and uses 11.1 million bytes of memory for the state set structure. It uses a 31-bit representation of the state and also stores the rotation through which each state was first found. Its memory consumption is remarkably small, considering that 3,674,160 × 31 bits is about 14.2 million bytes. Getting below this number was made possible by sharing common parts of states. Obviously, it is not possible to reduce memory consumption without limit. We derive an information-theoretic hard average lower bound of 6.07 million bytes that applies in this setting. We introduce a general-purpose variant of the data structure and end up with 8.9 million bytes and 48 s. We also discuss the performance of BDDs and perfect state packing in this application.     

Effects of calcination temperature on phase and microstructure evolution of BaTi4O9 powders

Calcining of the mixture of BaCO₃ and TiO₂ with a ratio 1:4 at different temperatures was carried out to synthesize BaTi₄O₉ powders. Phase evolution of the samples was studied using the differential thermal analysis (DTA) and X-ray diffractometry (XRD). Both techniques confirmed that the formation of BaTi₄O₉ started around 1000 °C. The XRD peaks showed that BaTi₄O₉ was most pronounced at 1250 °C. X-ray line broadening methods were employed to study the variation of particle size and microstrain of the BaTi₄O₉ powders. The Voigt function in a single line and the pseudo-Voigt function in the variance methods were used in our case. We found that both functions resulted in the same trends, i.e., the particle size increased with the temperature with the biggest size of 180 and 160 nm, whilst the microstrain yielded the opposite trend with the lowest values of 6.2 × 10^–3 and 1.1 × 10^–3. The scanning electron microscopy (SEM) study revealed the size of the large particles formed, due to agglomeration, to be about 0.5–1.9 μm. Furthermore, it was shown that irregular shapes of BaTi₄O₉ powders necked to each other appeared at 1000 °C and grew into ellipse and rod shapes at 1250 °C. Electronic Publication     

国有企业党风廉政建设中的问题及治理研究

剖析国有企业党风廉政建设中的突出问题。提出“推进国有企业党风廉政建设运用市场经济原则经营运作是重要途径;加强对企业经营管理者的监督管理是关键;完善法人治理结构、建立企业内部权力制衡机制是重要基础”的观点。