From distribution networks to smart distribution systems: Rethinking the regulation of European electricity DSOs

Distributed energy resources allow for new business models that have the potential to substantially change today's power system functioning paradigm. In particular, these changes pose challenges for distribution system operators (DSOs) and their regulation alike. This article sheds light on missing aspects in current regulation, recognizing DSOs as regulated monopolies, but also as key players along the supply chain. We provide insights on how regulation should be adjusted so that DSOs are incentivized to facilitate the market entry of welfare-enhancing technologies in a timely fashion, and to manage the distribution system efficiently in the presence of distributed energy resources.     

A trilevel programming approach for electric grid defense planning

This paper addresses the allocation of defensive or hardening resources in an electric power grid to mitigate the vulnerability against multiple contingencies. This planning problem is characterized by a defender-attacker-defender model which is formulated as a trilevel programming problem. In the upper level, the system planner identifies the components to be defended or hardened in order to reduce the damage associated with plausible outages. In the middle level, the disruptive agent determines the set of out-of-service components so that the damage in the system is maximized. Finally, in the lower level, the system operator minimizes the damage caused by the outages selected by the disruptive agent by means of an optimal operation of the power system. We propose a novel two-stage solution approach that attains optimality with moderate computational effort. The original trilevel program is first transformed into an equivalent bilevel program, which is subsequently solved by an efficient implicit enumeration algorithm. Numerical results show the effectiveness of the proposed methodology.     

格网定点式钉螺螺情信息系统的设计与实现

针对血吸虫病流行区人工实地查螺的特点,采用集成二次开发模式开发了一个基于GIS的螺情信息系统。探讨了一些关键技术,如ArcObjects组件库的应用,复杂地形格网图的绘制和编辑方法,基于胖客户机瘦服务器的信息管理机制,以及系统功能实现与地图无关的技术等。该系统的实现为研究局部钉螺孳生规律、建立以时间为主轴线的螺情信息链提供了基础,解决了血防工作中长期以来一部分工作未能实现信息化平台的问题,并在实践中取得了很好的应用效果。     

A Moving Grid Framework for Geometric Deformable Models

Geometric deformable models based on the level set method have become very popular in the last decade. To overcome an inherent limitation in accuracy while maintaining computational efficiency, adaptive grid techniques using local grid refinement have been developed for use with these models. This strategy, however, requires a very complex data structure, yields large numbers of contour points, and is inconsistent with the implementation of topology-preserving geometric deformable models (TGDMs). In this paper, we investigate the use of an alternative adaptive grid technique called the moving grid method with geometric deformable models. In addition to the development of a consistent moving grid geometric deformable model framework, our main contributions include the introduction of a new grid nondegeneracy constraint, the design of a new grid adaptation criterion, and the development of novel numerical methods and an efficient implementation scheme. The overall method is simpler to implement than using grid refinement, requiring no large, complex, hierarchical data structures. It also offers an extra benefit of automatically reducing the number of contour vertices in the final results. After presenting the algorithm, we demonstrate its performance using both simulated and real images. This work was supported in part by NSF/ERC Grant CISST#9731748 and by NIH/NINDS Grant R01NS37747.     

Mechanical behaviour of surface layer fibreglass-reinforced flexible pavements

The work presented in this paper aims at providing a better understanding of the mechanical response of surface layer fibreglass-reinforced flexible pavements. The surface reinforcement technique consists of installing a fibreglass grid in between the levelling layer (placed on the base course to seal and level the pre-existing distresses) and the wearing course (or overlay). Flexural fracture tests were performed on two-layered reinforced asphalt specimens composed of both levelling and wearing courses to simulate a real overlay structure. Three fibreglass grids characterised by different mechanical and/or geometrical properties were employed. Strain localisation and damage distribution were investigated using an in-house digital image correlation system capable of achieving highly accurate 2D full-field strain maps of the specimens during loading. Finally, an analytical model was developed on purpose to reproduce the mechanical response of the asphalt mixture-interlayer system.     

基于指标细分的顾客满意度提升策略分析

满意度研究成为目前质量领域和经济领域一个非常热门和前沿的话题，但时常发现一些研究采用的满意度提升策略分析方法过于简单，甚至出现指标重要性和影响力概念混淆的现象．指标细分是正确研究企业满意度提升策略的前提条件，而重要性＆影响力两维矩阵分析和奖惩分析是实现指标细分的有效方法．     

Photovoltaic technology in Malaysia: past,present, and future plan

This article presents solar energy or specifically the solar photovoltaic (PV) development outlook in Malaysia. The paper first introduces the massive potential of solar energy in the country, the key players in the solar energy development and the early solar energy policies, and programmes in the country. The most important to the PV development is the Malaysia Building Integrated Photovoltaic initiative, which is presented in this paper followed by an explanation on the Feed-in Tariff recently introduced in the country to encourage new solar PV projects. The outlook for solar PV in Malaysia is optimistic and as the uptake of solar PV increases, the unit cost is coming down rapidly. Solar PV is expected to be the most competitive Renewable Energy (RE) source, with the potential to achieve grid parity for electrical power in the country in the near future, and surpassing all other REs combined by 2050.     

Sensitivity of the predicted convective heat transfer in a cooled room to the computational fluid dynamics simulation approach

Computational fluid dynamics (CFD) plays an increasingly important role in the design, analysis and optimization of engineering systems. However, CFD does not necessarily provide reliable results. The most crucial numerical solution error is caused by inadequate grid resolution, and the key modelling error sources in CFD in ventilated indoor environments are turbulence modelling and diffuser modelling. Many researchers already proposed guidelines, but they based their analyses on local variables. In response, underlying study intended to verify the impact of the CFD simulation approach on the convective heat flux, an integral quantity. The authors tested several grids, Reynolds averaged Navier–Stokes turbulence models and diffuser models for three convection regimes in a cooled room. The diffuser modelling had a much larger impact than the grid and the turbulence modelling, as long as the jet dominated the airflow. So, CFD users, who want to model forced/mixed convection airflow indoors, certainly need to pay attention to the diffuser modelling.     

A CFD study into the influence of unsteady aerodynamic interference on wind turbine surge motion

To improve knowledge of the unsteady aerodynamic characteristics and interference effects of a floating offshore wind turbine (FOWT), this article focuses on the platform surge motion of a full configuration wind turbine with the rotating blades, hub, nacelle, and tower shapes. Unsteady aerodynamic analyses considering the moving motion of an entire configuration wind turbine have been conducted using an advanced computational fluid dynamics (CFD) and a conventional blade element momentum (BEM) analyses. The present CFD simulation is based on an advanced overset moving grid method to accurately consider the local and global motion of a three-dimensional wind turbine. The effects of various oscillation frequencies and amplitudes of the platform surge motion have been widely investigated herein. Three-dimensional unsteady flow fields around the moving wind turbine with rotating blades are graphically presented in detail. Complex flow interactions among blade tip vortices, tower shedding vortices, and turbulent wakes are physically observed. Comparisons of different aerodynamic analyses under the periodic surge motions are summarized to show the potential distinction among applied numerical methods. The present result indicates that the unsteady aerodynamic thrust and power tend to vary considerably depending on the oscillation frequency and amplitude of the surge motion.