Low order harmonic cancellation in a grid connected multiple inverter system via current control parameter randomization

In grid connected multiple inverter systems, it is normal to synchronize the output current of each inverter to the common network voltage. Any current controller deficiencies, which result in low order harmonics, are also synchronized to the common network voltage. As a result the harmonics produced by individual converters show a high degree of correlation and tend to be additive. Each controller can be tuned to achieve a different harmonic profile so that harmonic cancellation can take place in the overall system, thus reducing the net current total harmonic distortion level. However, inter-inverter communication is required. This paper presents experimental results demonstrating an alternative approach, which is to arrange for the tuning within each inverter to be adjusted automatically with a random component. This results in a harmonic output spectrum that varies with time, but is uncorrelated with the harmonic spectrum of any other inverter in the system. The net harmonics from all the inverters undergo a degree of cancellation and the overall system yields a net improvement in power quality.     

Integrating peer support initiatives in a large healthcare organization.

The Veterans Health Administration (VHA) adopted a strategic plan for mental health that emphasizes implementation of recovery-oriented services, including peer support. To provide a baseline for assessing change, a national survey was conducted of peer service delivery for veterans with mental illness, including those with comorbid substance abuse or homelessness. The number of participating programs was small. However, responses indicate that existing VHA peer services can be categorized as partnership services. Program and position structures, such as goals and training requirements are each described. Role and administrative or systems processes, such as acquiring staff buy-in and liability are also described. Future areas of consideration include dissemination of peer support in VHA and other healthcare systems, with specific efforts to increase training protocols, evaluation, and payment options for peers. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Beauty as an emotion: The exhilarating prospect of mastering a challenging world.

Beauty has received sparse attention from emotion theorists, some of whom have argued that aesthetic pleasure is cognitive in nature and too "disinterested" to be emotional. This view is supported by research suggesting that aesthetic pleasure is based on processing fluency. The authors review recent findings in the psychology of aesthetics and present two arguments. First, processing fluency explains the mild pleasure associated with simple or familiar objects, but it cannot account for the more intense pleasure associated with complex or novel objects. Immediately recognizing an object tends to be mildly pleasant, whereas sensing the prospect of successfully representing a complex object can be exhilarating. Second, to explain how these forms of aesthetic pleasures differ, a theory must go beyond cognitive dynamics. The authors' affect-based model of emotion differentiates aesthetic pleasures in terms of epistemic goals. Pretty, fluently processed stimuli implicate prevention goals that maintain and protect knowledge. Beautiful, novel stimuli implicate promotion goals that reshape and expand knowledge. The emotional nature of interest and awe are also discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Predicting the Erosion Rate of Chemically Treated Soil Using a Process Simulation Apparatus for Internal Crack Erosion

Chemical stabilization is an effective ground improvement technique for controlling erosion. Two stabilizers, lignosulfonate and cement, were used to study how effectively they could stabilize erodible silty sand collected from Wombeyan Caves, NSW, Australia. To conduct this research, four dosages of cement (0.5, 1, 1.5, and 2%) and four dosages of lignosulfonate (0.1, 0.2, 0.4, and 0.6%) by dry weight of soil were selected. All treated and untreated soil specimens were compacted to 90 and 95% of their maximum dry density to study the effect of compaction level on erodibility. The erosion characteristics of treated and untreated soil samples were investigated using a process simulation apparatus for internal crack erosion designed and built at the University of Wollongong. The findings of this study indicated that both chemical stabilizers increased the resistance to erosion because of their cementing properties. It was also found that the critical shear stress increased linearly with the amount of stabilizer, and the coefficient of soil erosion decreased as a power function of the critical shear stress.     

屏蔽技术(四)

（上接2010年第1期92页） 4．3．13 屏蔽薄膜控制面板 薄膜面板是一种嵌入了按钮的层压塑料结构，面板上透明的区域用于观察LED指示灯和湿示屏。南于必须在机箱上面开孔以便安装薄膜面板，所以薄膜面板也是影响机箱屏蔽效能的重要因素。薄膜面板的护板通常由铝构成，护板的每个顶角都有螺丝固定位置。即使每个顶角上的固定点都实现了良好的射频搭接（事实上很少这样），四个固定点之间也会形成四个电磁泄漏缝隙。     

Rewards-supply planning under option contracts in managing coalition loyalty programmes

We examine the problem of planning the supply of rewards in coalition loyalty programmes considering that the buyer–supplier relationships with commercial partners are governed by option contracts rather than wholesale price contracts similar to what is commonly used in practice. We develop a two-stage stochastic linear programme model with simple recourse which considers uncertain demand requirements, limited reward purchasing budgets, multiple programme partners of various sizes, point-liability control targets and overall profitability. A sampling average approximation scheme is used to solve the model. Numerical experiments show that option contracts perform better than wholesale price contracts when redemption demand uncertainty is high and the number of redemption partners is large. The results also suggest that the common practice of increasing redemption capacities is not the most effective way to cope with demand uncertainties. Programmes that reduce redemption demand variability and/or create better contracting structures are more promising in improving points-liability, redemption budget spending and overall profitability than traditional approaches.     

Mercury distribution and deposition in glacier snow over western China

Western China is home to the largest aggregate of glaciers outside the polar regions, yet little is known about how the glaciers in this area affect the transport and cycling of mercury (Hg) regionally and globally. From 2005 to 2010, extensive glacier snow sampling campaigns were carried out in 14 snowpits from 9 glaciers over western China, and the vertical distribution profiles of Hg were obtained. The Total Hg (THg) concentrations in the glacier snow ranged from <1 to 43.6 ng L(-1), and exhibited clear seasonal variations with lower values in summer than in winter. Spatially, higher THg concentrations were typically observed in glacier snows from the northern region where atmospheric particulate loading is comparably high. Glacier snowpit Hg was largely dependent on particulate matters and was associated with particulate Hg, which is less prone to postdepositional changes, thus providing a valuable record of atmospheric Hg deposition. Estimated atmospheric Hg depositional fluxes ranged from 0.74 to 7.89 μg m(-2) yr(-1), agreeing very well with the global natural values, but are one to two orders of magnitude lower than that of the neighboring East Asia. Elevated Hg concentrations were observed in refrozen ice layers in several snowpits subjected to intense melt, indicating that Hg can be potentially released to meltwater.     

助推能量采集

众多低功率工业传感器和控制器正在寻求以非传统能源作为主要或补充性供电源。利用现成的物理电源（例如,热电发生器或热电堆、压电或机电装置和光伏器件）来产生电力的换能器正在成为许多应用的适配电源。通过仅使用收集到的能量,众多无线传感器、远程监视器和其他低功率应用正在稳步成为接近“零”功率的设备（常被有些人称为“微功率”）。     

屏蔽技术(七)

（上接2010年第4期89页）4.7屏蔽材料4.7.1金属及其表面加工由于钢、铝价格低廉,易于切割、加工、折弯和连接,常被用做制造机箱的材料。铝的导电性较高,但容易发生化学反应,通常都要对其表面进行氧化处理,     

Energy dissipation distributions and dissipative atomic processes in amplitude modulation atomic force microscopy

Instantaneous and average energy dissipation distributions in the nanoscale due to short and long range interactions are described. We employ both a purely continuous and a semi-discrete approach to analyze the consequences of this distribution in terms of rate of heat generation, thermal flux, adhesion hysteresis, viscoelasticity and atomic dissipative processes. The effects of peak values are also discussed in terms of the validity of the use of average values of power and energy dissipation. Analytic expressions for the instantaneous power are also derived. We further provide a general expression to calculate the effective area of interaction for fundamental dissipative processes and relate it to the energy distribution profile in the interaction area. Finally, a semi-discrete approach to model and interpret atomic dissipative processes is proposed and shown to lead to realistic values for the atomic bond dissipation and viscoelastic atomic processes.