A novel method of suppressing the inrush current of transformers by using a series‐connected voltage‐source PWM converter

This paper proposes a novel method of suppressing the inrush current of transformers. A small‐rated voltage‐source PWM converter is connected in series to the transformers through a matching transformer. As the connected PWM converter serves as a resistor for the source current, no inrush phenomena occurs. The required rating of the PWM converter, which serves as the damping resistor for the inrush phenomena, is 1/400 that of the main transformers in single‐phase circuits. In three‐phase circuits, it is 1/900. The basic principle of the proposed method is discussed. Digital computer simulation is implemented to confirm the validity and excellent practicability of the proposed method using the PSCAD/EMTDC. A prototype experimental model is constructed and tested. The experimental results demonstrate that the proposed method can perfectly suppress the inrush phenomena. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 157(4): 56–65, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20174     

SBS改性沥青

介绍了沥青的特性，改性沥青的种类与性能，以及丁苯嵌段共聚物改性沥青的相容性，溶胀性，分散性等方面的研究进展，并提出了发展建议。     

提高太安堆积密度的结晶工艺研究

以季戊四醇经浓硝酸酯化后的粗制太安为原料，在溶课题上重结晶得精制成品太安，讨论了不同溶剂，结晶速度，结晶溶液pH值对太安堆积密度的影响。     

PRIVACY LEAKAGE IN HEALTH SOCIAL NETWORKS

Members of health social networks may be susceptible to privacy leaks by the amount of information they leave behind. The threat to privacy increases when members of these networks reuse their pseudonyms in other social networks. The risk of re‐identifying users from such networks requires quantitative estimates to evaluate its magnitude. The estimates will enable managers and members of health social communities to take corrective measures. We introduce a new re‐identification attack, the social network attack, that takes advantage of the fact that users reuse their pseudonyms. To demonstrate the attack, we establish links between MedHelp and Twitter (two popular social networks) based on matching pseudonyms. We used Bayesian networks to model the re‐identification risk and used stylometric techniques to identify the strength of the links. On the basis of our model 7‐11. 8% of the MedHelp members in the sample population who reused their pseudonyms in Twitter were re‐identifiable compared with 1% who did not. The risk estimates were measured at the 5% risk threshold. Our model was able to re‐identify users with a sensitivity of 41% and specificity of 96%. The potential for re‐identification increases as more data is accumulated from these profiles, which makes the threat of re‐identification more serious.     

Evolution axiale du coefficient de transfert de matière en colonne à bulles et en lit fluidisé triphasique

Liquid phase volumetric mass transfer coefficients for oxygen are determined in a three-phase fluidized bed and in a bubble column. The concept of exponential decreasing axial variation of volumetric mass transfer coefficient leads to a better representation of oxygen concentration profiles inside the column. Compared to the bubble column, k_la axial variations are more important in the lower part of the fluidized bed column, where solid particles increase the coalescence phenomenum, particularly with viscous liquids.     

Abstimmung von Produktions- und Transportlosgrößen zwischen Zulieferer und Produzent

Es wird eine Erweiterung des mehrstufigen stationären Losgrößenproblems mit endlichen Produktionsgeschwindigkeiten um den zeitpunktgeballten Transportvorgang vorgestellt. Diese Darstellung gibt die Beziehungen zwischen Zulieferer, Transporteur und Produzent adäquat wieder. Hinsichtlich der Abstimmung der Entscheidungsgrößen dieser organisatorischen Einheiten wird zwischen einer rein simultanen, einer rein sukzessiven sowie zweier gemischt simultan-sukzessiver Koordinationsarten unterschieden. An Hand einer analytischen Untersuchung werden Unterschiede und Gemeinsamkeiten der jeweiligen Entscheidungsgrößen und der daraus resultierenden Kostenfunktionen dargestellt. Schließlich zeigt eine numerische Analyse die Gesamtkostenunterschiede zwischen der rein simultanen und rein sukzessiven Koordinationsart auf.An extension is introduced to the multi-stage stationary lot-sizing problem with finite production rates by the time-concentrated transportation-process. This representation adequately demonstrates the relations between supplier, carrier and producer. With regard to the reconciliation of the decision variables of these institutional units one differentiates between a pure simultaneous, a pure gradual and two mixed simultaneous-gradual coordination methods. The differences and correspondences of the respective decision variables and the resulting cost functions are demonstrated by means of an analytical examination. Finally, a numerical analysis shows the distinctions in total cost between the pure simultaneous and pure gradual coordination method.     

Erosion wear response of ramie-epoxy composites using artificial neural network integrated with Taguchi technique

This paper aims on evaluating the erosion wear behavior of epoxy composites reinforced with ramie fibers. The possibility of reinforcing ramie fiber to improvise the wear resistance of epoxy is investigated in this study. Composites are fabricated by reinforcing multiple layers of woven ramie fiber mats into epoxy resin using conventional wet lay-up technique and erosion wear trials are conducted using solid particle erosion test setup. Taguchi analysis is done to assess the relative significance of each of the factors influencing the erosion rate using L₁₆ orthogonal array. The analysis reveals that the impact velocity followed by impingement angle are the most significant control factors affecting the erosion wear rate of ramie-epoxy composites. Steady state erosion analysis is done to ascertain the effect of each of the significant factors while keeping other factors fixed. Further, an analytical and predictive model based on the principle of neural computation is used to predict the rate of erosion wear of the composites and the obtained results are compared with the experimental outcomes. The worn morphologies of the eroded surfaces of the composites are studied and analyzed to identify possible mechanisms causing wear.