采用复合控制方式的并联混合型有源电力滤波器

在检测电源电流和负载电流控制方式的基础上，提出了一种复合控制方式。该控制方式的指令信号通过同时检测电源电流和负栽电流得到。它既具有上述两种控制方式的优点，又能克服它们各自的不足。此外，讨论了PWM逆变器的控制方法。在此基础上研制了一台并联混合型APF实验样机，进行了相应的实验研究。结果表明，采用复合控制方式的并联混合型电力有源滤波器稳定性高、谐波补偿效果好。     

旋转光纤中的拍长与偏振态保持能力

理论分析了旋转光纤在不同参考坐标系中的拍长及其与旋转光纤偏振态保持能力之间的关系——结果表明,旋转光纤没有确切的拍长定义,只有近似的用于描述旋转光纤偏振态保持能力的拍长计算公式。     

A Control Approach Based on Passive Behavior to Enhance User Interaction

This paper proposes a new control approach for an active (motorized) robotic walking support system based on passive behavior concept. The control approach aims to enhance the interaction between the support system and the user. The passive behavior of a support system allows the user to safely interact with the system since it removes the system's capability to move when there is no user's intention. This passive behavior is realized using imposed apparent dynamics, which uses the user's intention represented by the applied force/torque to derive the system's desired motion. The control approach is extended into a user-oriented motion control algorithm to adapt user's controlling characteristics. This is implemented by varying the point of application of the apparent dynamics. The control approach is further extended to use environment information and realize environment feedback concept. This is implemented by varying the parameters of the apparent dynamics based on environment data. Experimental results are presented to show the validity of the proposed control approach. [All rights reserved Elsevier].     

Modeling of a joint-type flexible endoscope based on elastic deformation and internal friction

Flexible endoscopes are widely used in minimally invasive surgical robot systems. Various kinematic models have been developed for describing the deformation of such endoscopes. For joint-type flexible endoscopes, most existing models neglect the effect of internal friction and cannot precisely show the shape.

In this paper, we propose a new nonlinear bending model. The rubber tube and metal net at each joint are approximated as a tube under elastic deformation and are assigned an equivalent bending stiffness. The internal friction force is also taken into account to build the moment balance equation at each joint. Groups of experiments were performed to validate the nonlinear model. The results closely confirm the model’s predictions. The model’s tip position error during the bending and unbending phases are 1.48?±?0.99?mm and 1.68?±?0.91?mm respectively; the bending angle errors are ?5.50?±?2.54° and 1.68?±?3.66°, respectively The model can also take account of the hysteresis effect of the bending, which is quite common for cable-driven flexible robots. Moreover, the model has good computational efficiency, making it suitable for real-time control.     

Estimating sub-pixel temperatures using the triangle algorithm

In water-deficient areas, water resource management requires evapotranspiration at high spatiotemporal resolution – an impossible situation given the trade-off between spatial and temporal resolutions in space-borne systems. Some researchers have suggested sharpening the Moderate Resolution Imaging Spectroradiometer (MODIS) land-surface temperature product with a resolution from 1 km to 250 m and a functional relationship between surface temperature (T _r) and normalized difference vegetation index (NDVI). Evapotranspiration at 250 m resolution can be obtained once every few days using this technique. Based on the interpretation of the triangular T _r–NDVI space and assuming uniform soil moisture conditions in a coarse pixel, this paper suggests an alternative algorithm – the triangle algorithm – for sharpening. The triangle algorithm was tested using Landsat 7 Enhanced Thematic Mapper Plus (ETM+) data from an arid zone. Sharpened surface temperatures and reference temperatures were compared at 60 m and 240 m resolutions. Root mean square errors with the triangle algorithm are smaller than those with a functional relationship between T _r and NDVI. This paper will also discuss the impact of soil moisture variations in the coarse pixel on the triangle algorithm. Finally we should mention that the triangle algorithm only applies to regions with non-stressed vegetation canopies.     

提高氯乙烯聚合转化率的试验研究

研究了氯乙烯聚合转化率的影响因素,并考察了转化率对PVC颗粒特性的影响情况。在聚合温度不变的条件下,氯乙烯的聚合转化率随聚合反应后期釜内压力的降低而增大;提高聚合温度和增加引发剂用量可有效提高聚合反应速率,缩短达到高转化率的时间;转化率宜控制在80%~85%,过高则PVC的增塑剂吸收量降低。     

Probing Sound Speed of an Optically-Trapped Bose Gas with Periodically Modulated Interactions by Bragg Spectroscopy

A Bose–Einstein condensate (BEC) with periodically modulated interactions (PMI) has emerged as a novel kind of periodic superfluid, which has been recently experimentally created using optical Feshbach resonance. In this paper, we are motivated to investigate the superfluidity of a BEC with PMI trapped in an optical lattice (OL). In particular, we explore the effects of PMI on the sound speed and the dynamical structure factor of the model system. Our numerical results, combined with the analytical results in both the weak-potential limit and the tight-binding limit, have shown that the PMI can strongly modify the sound speed of a BEC. Moreover, we have shown that the effects of PMI on the sound speed can be experimentally probed via the dynamic structure factor, where the excitation strength toward the first Bogoliubov band exhibits a marked difference from the non-PMI one. Our predictions of the effects of PMI on the sound speed can be tested using the Bragg spectroscopy.     

焦炭塔裙座隐患分析及整治

从应力、生产过程、结构形式等方面，分析了焦炭塔裙座与塔壁焊口部分开裂的原因。根据分析结果制定相应的整改措施，并对整改后的结构形式进行强度校核。实际应用结果表明获得了预想的效果，焦炭塔裙座改造成功。     

Feature article - Development of RTV Silicone Coatings in China: Overview and Bibliography

The development of room temperature vulcanized (RTV) silicone coatings in China began in early 1985. Over the course of time, they have come to be widely used in China. At present, nearly 800,000 kg of RTV coatings are used every year. They have successfully prevented serious pollution flashover of traditional glass and porcelain insulators and radically reduced the costs of maintaining transmission lines in polluted areas. RTV silicone coatings have been extensively studied in China. The main aspects of the research include improvements in the properties of the formula for better adhesion to porcelain and control of leakage current, the hydrophobicity transference mechanism, and aging. These decades of research have successfully promoted the development of RTV silicone coatings in China. The history of the development and research of RTV silicone coatings in China are discussed in this article.     

Evaluation of the Degradation of Generator Stator Ground Wall Insulation Under Multistresses Aging

The actual stator bars of an 18 kV/300 MW generator were used for accelerated multistress aging tests to investigate the degradation of ground insulation. An aging system with combined stresses including thermal, electrical, mechanical vibration, and thermomechanical factors was used to test the aging of stator bar specimens. The nondestructive parameters including partial discharge (PD) quantities and dissipation factor parameters were measured during aging test in order to evaluate the degradation of stator ground wall insulation. At the end of the aging test, an AC breakdown test was performed on the bars in order to obtain the remaining breakdown voltage (BDV) after their nondestructive data had been measured. The changes of nondestructive parameters indicated that the degradation of ground wall insulation. For example, the changes of skewness of indicated the shape of voids in ground insulation changes from flat to narrow, and even exhibits treeing, which is dangerous to insulation because it shortens the effective distance of insulation between high voltage and the ground. The results obtained are summarized as follows. The BDV data fit a Weibull distribution. The correlation between the dissipation factor, the PD parameters, and the breakdown voltage were analyzed, among which the skewness of the average discharge had the most correlation with breakdown voltage.