大型汽轮发电机失步振荡的网机耦合仿真

在研究分析了大量有关资料,特别是一些国际组织的研究成果,结合各系统、各制造厂的实践经验,对1039MW汽轮发电机组失步振荡进行了网机耦合仿真,对不同电网故障造成的发电机、轴系和电网的冲击大小进行计算,并评估其造成的轴系疲劳寿命损失。研究结果表明：机组在失步振荡20个周期,发电机绕组端部振动、绕组发热、轴系疲劳寿命损耗均在许可范围内,机组承受失步振荡的能力完全满足标准和技术规范要求。     

Analysis on energy intensive industries under Taiwan's climate change policy

This study addresses the planning and implementation of energy, industry, and carbon economy policies concerning the development of the Taiwan's energy intensive industries from perspective of climate change. As a newly industrialized country, Taiwan attaches greater importance to the development of green energy and low-carbon industries, in cooperation with global pressure for carbon reduction due to climate changes, through energy and industrial conferences. Thus, in the past year the Taiwanese government constructed four laws concerning energy and carbon reduction in order to drive the green energy industry; furthermore, it plans to reduce current carbon emission benchmarks. Nevertheless, statistical analysis found that in the last decade, energy intensive industries have presented structural unbalance regarding energy consumption, CO₂ emissions, energy intensity, contributions to the GDP, and product value. Industries in the industrial sector have high energy consumption, high carbon emissions, and increase total domestic consumption and carbon emissions, which have disproportionate contributions to industrial added value; nevertheless, the government continues to approve investments for such energy intensive industries, and results in continuous increases in energy consumption and carbon emissions. This contradictory phenomenon indicates that newly industrialized countries rely on a manufacturing economic structure, which is difficult to adjust and violates the trends of a global low-carbon economy. Hence, the government must examine and adjust such unbalanced industrial structures, where such adjustments are executed in a fair and just manner, and encourage the development of high value-added measures for low-carbon manufacturing and service sectors to become equal with competitors in a global economy.     

Calculating double-exponential diode model parameters frompreviously extracted single-exponential model parameters

A procedure is proposed to calculate both pre-exponential reverse currents of the double-exponential model of a diode's current-voltage experimental characteristics from previously extracted reverse current and diode quality factor of the diode's single-exponential model. The procedure is illustrated by modelling the drain-body junction of a MOSFET including its parasitic series resistance     

A simple device for detecting impact time in impact-echo testing of concrete

The objective of this paper is to describe a simple device for detecting the time of an impact and to demonstrate its efficiency in measuring the depth of surface-opening cracks in concrete. Surface-opening cracks in concrete are relatively deep so that a mechanical impact instead of an ultrasonic transmitter is used to generate stress waves with enough energy for successful evaluation. A technique called the time-of-flight diffraction technique with impact-generated stress waves is an efficient method for detection of surface-opening cracks in concrete. Because the initial time of the impact is unavailable in a mechanical impact device, two receivers are employed in the test. One of the receivers is used to determine the time of the impact indirectly. The present study developed a simple device to record the time of impact initiation. The device comprises a conductive impact device, a sensing film, and an auxiliary circuit. With the device, stress waves are generated and the time of impact is detected so that the evaluation work needs only a single receiver. Laboratory studies were carried out on concrete specimens containing cracks with depths of 0.158 and 0.90 m. Field studies were performed on a dam damaged by an earthquake. Experimental results show that the new device can be used to accurately determine the crack depth in concrete. Using the device, the cost and effort for evaluation and signal analysis are reduced, which largely enhances the evaluation efficiency.     

The accuracy of ultrasonography and 201Tl-99mTc subtraction scan in localization of parathyroid lesions

Pulsed xenon chloride excimer and holmium laser-tissue interaction is primarily based on tissue water vaporization. Consequently, each ablative laser pulse produces a rapidly expanding and imploding vapour bubble in blood or the target tissue. In experimental studies, explosive water vaporization is the major mechanical cause of observed tissue dissections. By reduction of the induced bubble volume, a reduction in experimentally and clinically observed dissections after coronary excimer laser angioplasty is to be expected. This reduction of mechanical damage, however, in combination with efficient and substantial plaque debulking is the major challenge in the development of laser angioplasty.     

Analysis of slow-wave transmission lines on multi-layeredsemiconductor structures including conductor loss

Metal lines on semiconductor devices and circuits sometimes show slow-wave phenomena. To determine signal transmission characteristics along the lines, the typical assumption that metal is perfectly conducting is not always valid. A simple and accurate means is used here to include metallic loss in spectral domain analysis of planar transmission lines built on multilayer semiconducting media. Experimental results with a modulation-doped field-effect transistor (MODFET) structure and comparison with the calculations are presented     

Flexible Multi‐Colored Electrochromic and Volatile Polymer Memory Devices Derived from Starburst Triarylamine‐Based Electroactive Polyimide

Flexible multi‐colored electrochromic and volatile memory devices are fabricated from a solution‐processable electroactive aromatic polyimide with starburst triarylamine unit. The polyimide prepared by the chemical imidization was highly soluble in many organic solvents and showed useful levels of thermal stability associated with high glass‐transition temperatures. The polyimide with strong electron‐donating capability possesses static random access memory behavior and longer retention time than other 6FDA‐based polyimides. The differences of the highest‐occupied and lowest unoccupied molecular orbital levels among these polyimides with different electron‐donating moieties are investigated and the effect on the memory behavior is demonstrated. The polymer film shows reversible electrochemical oxidation and electrochromism with high contrast ratio both in the visible range and near‐infrared region, which also exhibits high coloration efficiency, low switching time, and the outstanding stability for long‐term electrochromic operation. The highly stable electrochromism and interesting volatile memory performance are promising properties for the practical flexible electronics applications in the future.