Symmetrical components in the time domain and their application topower network calculations

Although the symmetrical component transformation has existed for 80 years, its application in the time-dependent form is practically restricted to the electric-machine theory. In the power systems field one uses the transformation applied to steady-state sinusoidal phasors in a nonunitary form for fault calculations. For time-domain calculations the real equivalent, 0, α, β, is preferred, usually extended to 0, d, q-components. In network calculations, however, the application of time-dependent symmetrical components makes sense, since many net-component parameters are already available in this form. In this paper a short historical overview of the symmetrical-component transformation and the application of unitary and orthogonal transformations are presented. From these general transformations logic choices for base quantities necessary in per unit calculations are derived. The relations between real and complex transformations, steady-state phasors and well-known sequence networks are given and illustrated through the use of some examples with asymmetrical faults     

Challenges in developing an integrated catchment management model

Directives and policies increasingly call for more integrated management of land and water. Frameworks such as integrated catchment management may address these calls, and yet their implementation requires decisions to be taken under conditions of extreme complexity and uncertainty. This paper summarises a participatory framework through which decision‐makers, experts and system modellers can collaboratively develop an integrated model to support such decisions. A feasibility study showed the potential of the framework. An operational version of the model, able to analyse the effects of 50 management options on 20 indicators, is estimated to require in the order of 225 man‐months from system modellers, alongside substantial inputs from stakeholders. The significant technical challenges confronting such an exercise may be overshadowed by the institutional challenges, including the fundamental question of whether organisations are truly committed. However, the reward for overcoming such challenges is the opportunity to achieve genuine improvements in the social, economic and environmental quality of our catchments.     

寻求精确且可靠的振动感测适用于以状态为基础的预知维护

精密的工业制程对于马达与相关机械有效而且一致性运作的依赖日益提高.在机械中的失衡、缺陷、松散、以及其它异常现象通常都会转换成振动,而接着就是失去精密度与安全性的考虑.假如不加以处理的话,除了性能与安全的问题之外,当设备需要脱机修理时,生产力的损失将会变得无可避免.     

Developing community capacity to treat post-deployment mental health problems: A public health initiative.

Meeting the mental health needs of Veterans returning from recent deployment requires the coordinated effort of partnerships across Department of Defense (DoD), Department of Veterans Affairs (VA), and state and local communities. Although the proportion of Veterans of Iraq and Afghanistan who have accessed VA health care has grown, the majority of these new combat Veterans have yet to present for VA care. The stigma associated with reporting a deployment-related mental health problem may be one factor in this, but access to treatment may also be an important concern among the one third of American Veterans who live in rural or highly rural areas. As these Veterans are more likely to present to a primary care, faith-based or mental health provider in their own community, partnerships between community providers, DoD, and VA are of critical importance in ensuring appropriate care, regardless of treatment setting. In an effort to improve services and access to services, especially to rural Veterans, an educational public health initiative was created to educate community providers about military culture, deployment-related mental health issues, VA resources, and evidence-based treatments. We describe the development, dissemination and evaluation of this initiative, as well as lessons learned for future similar endeavors. (PsycINFO Database Record (c) 2011 APA, all rights reserved)