CITIZEN PARTICIPATION AND URBAN CAPACITY BUILDING: REPRESENTATION AND CONFLICT

The paper focuses on two major urban capacities to which citizen participation policies are expected to contribute—the capacity to represent diverse interests and the capacity to sustain conflict. The comparative strengths and weaknesses of two different citizen participation structures are considered—single-purpose, appointed advisory boards and multiple-purpose, elected neighborhood councils. Drawing from both the literature and original data from Wichita's innovative citizen participation approach, the paper suggests ways in which each participatory form contributes to urban representation and the avoidance of rancorous conflict.     

THE IMPACT OF TELEVISION COVERAGE OF CITy COUNCIL

In this article we examine the impact of a local government reform or innovation that is being widely adopted in American cities—television coverage of city council meetings. Television coverage of meetings may be viewed as one of a series of innovations directed at increasing citizen awareness of the governing process by increasing the visibility and public scrutiny of formal decision making processes. It is often viewed as a public service, is certainly not controversial, and is often adopted without due consideration of potential consequences. But like so many well-intended reforms, television coverage of governmental deliberations does alter the context of politics and has a potential impact far broader than originally intended. A variety of such potential impacts with respect to the quality of policy discussion, accountability, and political recruitment are explored.     

WPSS输入反馈时延的自适应分段补偿设计

广域电力系统稳定器(WPSS)是抑制电力系统区间模式振荡最有效的方法之一。WPSS以相量测量单元(PMU)量测的远方同步信号为反馈输入,在将其应用到工程实际时需要着重考虑远方信号的时延问题。从长期来看,时延通常会在一定范围内呈现一定的随机分布特性。文中设计了一种自适应分段时延补偿器,将时延分为若干个区间,对每一个区间设计时延补偿。时延补偿器根据在线量测得到的实际时延自适应地调整控制器的时延补偿区间,以达到最优补偿的目的。文中重点讨论了时延分段的方法以及时延补偿器自适应调整的规则。将提出的自适应分段时延补偿器在两区四机系统中实现,不同工况下的数值仿真结果表明了补偿器的有效性和鲁棒性。RTDS实验结果进一步表明所提方法可行且有效。该方法考虑了长时期内时延的变化,符合工程实际情况,适合于现场工程应用。     

A VARIABLE VOLTAGE AND FREQUENCY SCHEME TO OPTIMIZE THE EFFICIENCY OF A WIND-DRIVEN INDUCTION GENERATOR

ABSTRACT

The most recent approaches to harness energy from the wind utilizing induction generators has been made possible by advances in induction motor control using power electronic drives. The freedom in adjusting terminal voltage or current, and frequency al lows operation of the induction machine to fit any desired characteristic. The purpose of this paper is to propose a scheme using this technology to convert wind energy to electricity at maximum wind turbine power and induction generator efficiency. The Electromagnetic Transients Program (EMTP) is used to simulate the control of the induction generator. Simulation results show that this system operates as predicted in a stable fashion at the desired operating point.     

Extractive Metallurgy of Tantalum

Abstract

This paper presents a brief review of extractive metallurgy of tantalum starting from processing of its ore to two pure intermediates K₂TaF₇ and Ta₂O₅ and their conversion to pure tantalum metal by various technically feasible processes. Though tantalum metal can be produced by several means only two processes - sodium reduction of K₂TaF₇ and fused salt electrolysis of K₂TaF₇ in the presence of oxide, have been successful on industrial scale. Besides providing salient features of these two processes, the paper presents brief accounts of studies carried out on the reduction of oxide by metallic reductants - calcium and aluminium as well as nonmetallic reductants - carbon and carbon-nitrogen. The crude metal obtained by various reduction techniques outlined are purified either by solid state pyrovacuum treatment or by melt refining in an electron beam furnace. Mechanism of refining processes taking place during these post reduction treatments are also included in the review.     

Effects of pH on Calcium, Zinc, and Phytate Solubilities and Complexes Following In Vitro Digestions of Soy Protein Isolate

High intraluminal gastric pH values in young infants could affect the bioavailability of zinc in soy protein isolate formula. This investigation examined the effects of pH on the solubilities and complexes of calcium, zinc and phytate following in vitro pepsin and pepsin-pan-creatin digestions of soy protein isolate. The results of these in vitro studies suggested that (1) high intraluminal gastric pH values could lead to the formation of insoluble calcium-zinc-phytate complexes in the stomach following ingestion of soy protein isolate and (2) high intraluminal gastric pH values would only affect resultant soy zinc solubility in the small intestine in the absence of exogenous calcium or zinc but not in the presence of same.     

Extractive Metallurgy of Tantalum

This paper presents a brief review of extractive metallurgy of tantalum starting from processing of its ore to two pure intermediates K₂TaF₇ and Ta₂O₅ and their conversion to pure tantalum metal by various technically feasible processes. Though tantalum metal can be produced by several means only two processes – sodium reduction of K₂TaF₇ and fused salt electrolysis of K₂TaF₇ in the presence of oxide, have been successful on industrial scale. Besides providing salient features of these two processes, the paper presents brief accounts of studies carried out on the reduction of oxide by metallic reductants – calcium and aluminium as well as nonmetallic reductants – carbon and carbon–nitrogen. The crude metal obtained by various reduction techniques outlined are purified either by solid state pyrovacuum treatment or by melt refining in an electron beam furnace. Mechanism of refining processes taking place during these post reduction treatments are also included in the review.