A Distributed State Estimator Utilizing Synchronized Phasor Measurements

With the creation of balancing authorities by the North American Reliability Council that span large portions of the North American interconnection, and stringent requirements for real time monitoring of power system evolution, faster and more accurate state estimation algorithms that can efficiently handle systems of very large sizes are needed in the present environment. This paper presents a distributed state estimation algorithm suitable for large-scale power systems. Synchronized phasor measurements are applied to aggregate the voltage phase angles of each decomposed subsystem in the distributed state estimation solution. The aggregated state estimation solution is obtained from the distributed solution using a sensitivity analysis based update at chosen boundary buses. Placement of synchronized phasor measurements in the decomposed subsystems is also investigated in this paper. Test results on the IEEE 118-bus test bed are provided     

Flocculation morphology: effect of particulate shape and coagulant species on flocculation.

Flocculation morphology is a new concept that investigates the morphological characteristics of colloidal particles and coagulants in water during the flocculation process, and the influence that these characteristics have on flocculation process efficiency. This paper is a summary of advances in research on this topic over several years. Morphological characteristics of colloids in natural waters and different kinds of hydrolysed coagulants are investigated, and their effect on colloid stability, flocculation kinetics and efficiency is analysed. It is confirmed that the traditional theory has some deviations in coagulation of nonspherical particles, and these deviations are revised by the flocculation morphology model. Flocculation morphology can not only promote research about flocculation theory, but also instruct the production, application and flocculation control. It can be foreseen that more progress will be made in research and application of flocculation morphology in the near future.     

Modeling electromigration lifetime under bidirectional currentstress

Electromigration reliability of interconnect under bidirectional current stress has been studied in a wide frequency range (mHz to 200 MHz). Experimental results show that the AC lifetime rises with the stress current frequency. The current density exponent and the activation energy of AC lifetime are found to be twice that of DC lifetime. Pure AC current stress failure at extremely high current density is believed to result from thermal migration of metal at hot/cold transition points     

Comparison of Displacement and Mixing Diffusers

In order to cumpare the peformance of different supply diffuers of ventilation air, the airflow passern, temperature stratifiation and contaminant dispersion in a furnitured office ventilated by three kinds of air diffuer were numerically investigated. The air diffuers studied in this paper are a quarter-cylinder displacement diffuer on the floor and mixing diffuers (linear and vortex diffuers) on the ceiling. The heat sources in the of-fice are considered to be 50% convective and 50% radiative. The k-? two-equatwn model of turbulence is employed to predict the turbulent diffusion. The results show that the displacement diffuser provides a rather uniform flow field with low velocify in most areas, and the vertical temperature difference from floor to ceiling is as high as 6 K. With the linear diffuser, the air velociry is high, and the temperature is uniform both horizontally and vertically. The air velocity generated by the vortex diffuser is moderate. The distributions of the temperature and the contaminant are rather uniform.     

Variations in Spectral Slope in Lake Taihu,a Large Subtropical Shallow Lake in China

Spectral slope (S), describing the exponential decrease of the absorption spectrum over a given wavelength range, is an important parameter in the study of of chromophoric dissolved organic matter (CDOM) dynamics, and also an essential input parameter in remote sensing models. Furthermore, S is often used as a proxy for CDOM composition, including the ratio of fulvic to humic acids and molecular weight. The relative broad range in S values reported in the literature can be explained by the different spectral ranges and fitting methods used. A single exponential model is used to fit the S values for 17 investigations involving 458 samples in Lake Taihu from January to October in 2004. The average S value was 15.18 ± 1.39 μm⁻¹ for the range of 280–500 nm, which fell within the range reported in the literature. The frequency distribution of S value basically obeyed a normal distribution. Significant differences in S values between summer and other seasons showed that phytoplankton degradation was one of the important sources of CDOM in summer, whereas CDOM mainly came from the river input in other seasons. Furthermore, the estimated S value decreased with increasing wavelength range used in regression. The maximum and minimum values derived from the regression were 17.89 ± 1.25 μm⁻¹ and 13.62 ± 2.11 μm⁻¹ for the wavelength ranges of 280–380 nm and 400–500 nm, respectively, a decrease of 23.9%. S values significantly decreased with the increase of CDOM absorption coefficients. CDOM absorption coefficients could be more appropriately estimated from exponential model introducing the variation of S with absorption coefficients, making them useful for a remote sensing bio-optical model of Lake Taihu. DOC-specific absorption coefficient a*(λ) and the parameter M describing molecular size of the humic molecules could also be used as a proxy for the sources and types of CDOM. A general relationship was found between S and a*(λ), and M values. S increased with the decrease of DOC-specific absorption coefficient and the increase of M corresponding to the decrease of molecular weight.     

土壤γ辐射剂量率间接测量中的^222Rn析出和含水量修正

本文针对Ｂｅｃｋ公式的局限性，对土壤的含水量和＾２２２Ｒｎ析出引起的γ辐射剂量率变化进行了修正。通过浙江省５７６组测量数据的实验拟合，给出了剂量率计算的修正公式。该公式应用到浙江省自身的测量数据上，使计算的总体均值与实测均值仅相差０．８％；每一点位的计算值与实测值相比，平均仅相差３．４％，其比值离散性与实验误差相一致。而Ｂｅｃｋ公式的计算结果与实测剂量率相比较，以上两项分别偏离＋１０％和１５．２％     

A new family of yeast genes implicated in ergosterol synthesis is related to the human oxysterol binding protein

We have identified three yeast genes, KES1, HES1 and OSH1, whose products show homology to the human oxysterol binding protein (OSBP). Mutations in these genes resulted in pleiotropic sterol-related phenotypes. These include tryptophan-transport defects and nystatin resistance, shown by double and triple mutants. In addition, mutant combinations showed small but apparently cumulative reductions in membrane ergosterol levels. The three yeast genes are also functionally related as overexpression of HES1 or KES1 alleviated the tryptophan-transport defect in kes1Δ or osh1Δ mutants, respectively. Our study implicates this new yeast gene family in ergosterol synthesis and provides comparative evidence of a role for human OSBP in cholesterol synthesis.     

单齿泵削角的优化设计

给出了单齿泵削角的优化模型与计算实例，并对理论设计与实验进行了比较分析。     

3^n阶矩阵乘法的分块算法

针对３＾ｎ阶矩阵的乘法运行，给出了一种分块算法，其乘法运行量比常规的矩阵乘法计算方法和补零的基－２算法都有所减少。