基于差分蜂群算法的电力系统经济负荷分配

针对电力系统经济负荷分配问题,提出一种有效的差分蜂群算法．受差分进化算法的启发,该算法基于差分进化操作改进了雇佣蜂的搜索方式,提高了探索能力和收敛速度．此外,提出一种有效的修复机制以保证新个体的可行性．该算法在带有阀点效应和多燃料特征的典型电力系统经济负荷分配问题上进行了测试．仿真结果验证了所提算法的有效性．     

反向传播网络—吸光光度法同时测定生物实样中的锌和铜

研究了新显色剂 1 ,1 ,5-二 ( 2 -羟基 5 溴苯 ) 3 氰基甲日 (HBPCF)和锌及铜及铜的显色反应 ,并以反向传播人工神经网络———吸光光度法 ,对花生仁和绿豆等实际生物试样中锌及铜的含量 ,进行了同时测定。     

调制光安全保护系统的设计

介绍了利用红外线的发射与接收所构成的光束保护系统。红外线的发射与接收形成一“安全网” ,利用其档光性能 ,可以实现安全防范功能。为提高系统抗干扰性能 ,采用调制的红外光线 ,经过信号处理 ,驱动继电器动作 ,从而实现报警和保护。重点阐述了光束保护系统的基本工作原理 ,并给出了主要硬件原理图。     

Building language resources for a Multi-Engine English-Filipino machine translation system

In this paper, we present the building of various language resources for a multi-engine bi-directional English-Filipino Machine Translation (MT) system. Since linguistics information on Philippine languages are available, but as of yet, the focus has been on theoretical linguistics and little is done on the computational aspects of these languages, attempts are reported here on the manual construction of these language resources such as the grammar, lexicon, morphological information, and the corpora which were literally built from almost non-existent digital forms. Due to the inherent difficulties of manual construction, we also discuss our experiments on various technologies for automatic extraction of these resources to handle the intricacies of the Filipino language, designed with the intention of using them for the MT system. To implement the different MT engines and to ensure the improvement of translation quality, other language tools (such as the morphological analyzer and generator, and the part of speech tagger) were developed.     

NodeTrix: a hybrid visualization of social networks

The need to visualize large social networks is growing as hardware capabilities make analyzing large networks feasible and many new data sets become available. Unfortunately, the visualizations in existing systems do not satisfactorily resolve the basic dilemma of being readable both for the global structure of the network and also for detailed analysis of local communities. To address this problem, we present NodeTrix, a hybrid representation for networks that combines the advantages of two traditional representations: node-link diagrams are used to show the global structure of a network, while arbitrary portions of the network can be shown as adjacency matrices to better support the analysis of communities. A key contribution is a set of interaction techniques. These allow analysts to create a NodeTrix visualization by dragging selections to and from node-link and matrix forms, and to flexibly manipulate the NodeTrix representation to explore the dataset and create meaningful summary visualizations of their findings. Finally, we present a case study applying NodeTrix to the analysis of the InfoVis 2004 coauthorship dataset to illustrate the capabilities of NodeTrix as both an exploration tool and an effective means of communicating results.     

Fracture toughness and fracture mechanisms of PBT/PC/IM blend

The static and impact fracture toughnesses of a polybutylene terephthalate/polycarbonate/impact modifier (PBT/PC/IM) blend were studied at different temperatures. The static fracture toughness of the blend was evaluated via the specific fracture work concept and the J-integral analysis. A comparison of these two analytical methods showed that the specific essential fracture work, W _e, was equivalent to the obtained by the ASTM E813-81 procedure, representing the crack initiation resistance of the material. The discrepancy between W _e and of ASTM E813-89 was caused by the extra energy component in consumed by a 0.2 mm crack growth. Impact fracture toughness was also analysed using the specific essential fracture work approach. When the fracture was elastic, W _e was equivalent to the critical potential energy release rate, G _IC, obtained via LEFM analysis. Temperature and strain-rate effects on the fracture toughness were also studied. The increase in impact toughness with temperature was attributed to two different toughening mechanisms, namely, the relaxation processes of the rubbery particles and the parent polymers in a relatively low-temperature range and thermal blunting of the crack tip at higher temperatures. The enhancement in static fracture toughness at temperatures below — 60 °C was thought to be caused by plastic crack-tip blunting, but the monotonic reduction in yield stress was largely responsible for the toughness decreasing with higher temperatures. The temperature-dependent fracture toughness data obtained in static tests could be horizontally shifted to match roughly the data for the impact tests, indicating the existence of a time-temperature equivalence relationship.     

The essential work of fracture for tearing of ductile metals

A simple energy balance analysis is presented for the tearing of ductile sheet metals using the trousers test. It is shown that the specific essential work of fracture (w _e ) for tearing can be estimated by extrapolating the straight line relationship between the tearing force per unit thickness and the trousers leg width to zero leg width. There are two contributions to the specific essential work of fracture: one is due to the localised plastic shearing work in a zone contiguous with the torn edges (w _e1 ) and the other is the final out-of-plane tearing work (w _e2 ).

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Résumé En utilisant le Trousers Test, on présente une analyse simple d'équilibre énergétique dans le cas du déchirement de feuilles métalliques ductiles. On montre qu'il est possible d'estimer le travail spécifique de rupture en déchirement w _e en extrapolant la relation linéaire qui lie la force de déchirement par unité d'épaisseur et la largeur de l'échantillon caractéristique entre une valeur 0 et une valeur donnée. Deux éléments contribuent au travail spécifique essentiel de rupture, l'un est dû au travail de cisaillement plastique local dans une zone contigue aux bords de l'arrachement (w _e1 ) et l'autre est le travail de déchirement final hors du plan de la feuille (w _e2 ).

     

Structure and function of maladaptive cognitions in Pathological Internet Use among Chinese adolescents

This study empirically investigated the structure and function of maladaptive cognitions related to Pathological Internet Use (PIU) among Chinese adolescents. To explore the structure of maladaptive cognitions, this study validated a Chinese Adolescents’ Maladaptive Cognitions Scale (CAMCS) with two samples of adolescents (n1 = 293 and n2 = 609). The results of the exploratory factor analysis and confirmatory factor analysis revealed that CAMCS included three distinct factors, namely, “social comfort,” “distraction,” and “self-realization.” To examine the function of maladaptive cognitions, this study tested an updated cognitive-behavioral model in the third sample of 1059 adolescents. The results of structural equation model analyses verified both the direct effect of maladaptive cognitions on PIU and their mediating role in the relationships between distal factors (social anxiety and stressful life events) and PIU among Chinese adolescents. Theoretical and practical implications of these findings were discussed.     

The essential work of plane stress ductile fracture of a strain-aged steel

The paper reports the results of an experimental investigation on the essential work of fracture of a strain-aged low carbon (0.1% C) temper-rolled 16-gauge sheet steel which has been subjected to pre-strain levels of 2 to 12% and ageing temperatures of 80 and 100C. Deep edge-notched tension specimens were used to determine the specific essential work by extrapolating the straight-line relationship between the specific work of fracture (W _f) and ligament length (I) to zero ligament length. The strain-aged steels at 80 and 100 give approximately the same specific essential fracture work of 0.18 to 0.20 J mm^–2 which is independent of the amount of prestrain. Advancing crack opening displacements (C.O.D.) have also been analysed, which give 0.60 to 0.63 mm for the strain-aged steels. For comparison, the prestrained but unaged steels have a higher essential work of fracture of 0.275 J mm^–2 and a larger C.O.D. of 0.73 mm. It is concluded, therefore, that the causes of strain-ageing embrittlement are primarily due to the reduction of both the essential work of fracture and the advancing C.O.D. at the crack tip end region.     

交联型水性聚氨酯树脂的合成研究

用聚乙二醇和甲苯二异氰酸酯等进行预聚反应制备交联型水性聚氨酯树脂。系统地研究了nNCO／nOH(聚乙二醇)值对膜力学性能及玻璃化转变温度的影响，并考察了nNCO/nOH(总)值及交联剂三羟甲基丙烷的用量对乳液稳定性的影响。