A 155 Mbps laser diode driver with automatic power and extinction ratio control

An integrated laser diode driver(LDD) driving an edge-emitting laser diode was designed and fabricated by 0.35 μm BiCMOS technology. This paper proposes a scheme which combines the automatic power control loop and temperature com-pensation for modulation current in order to maintain constant extinction ratio and average optical power. To implement tem-perature compensation for modulation current,a novel circuit which generates a PTAT current by using the injecting base current of a bipolar transistor in saturation region,and alternates the amplifier feedback loop(closed or not) to control the state of the current path is presented. Simulation results showed that programmed by choice of external resistors,the IC can provide modu-lation current from 5 mA to 85 mA with temperature compensation adjustments and independent bias current from 4 mA to 100 mA. Optical test results showed that clear eye-diagrams can be obtained at 155 Mbps,with the output optical power being nearly constant,and the variation of extinction ratio being lower than 0.7 dB.     

The limit analysis in soil and rock： a mature discipline of geomechanics

The solution of a slope stability problem can be approached by its least upper-bound and maximum lower-bound with high accuracy. The limit equilibrium methods that employ vertical slices imply a lower bound of the factor of safety. It has been successfully extended to the area of active earth pressure analysis that accounts for different input of locations of earth pressure applications. Those methods that employ slices with inclined interfaces give an upper-bound approach to the stability analysis. It enjoys a sound mechanical background and is able to provide accurate solutions of soil plasticity. It has been successfully extended to the area of bearing capacity analysis in which various empirical coefficients are no longer necessary. The 3D upper- and lower-bound methods under this framework have been made possible and show great potential for solving various engineering problems.     

乡村民主的困境和现实出路

村民自治从产生到制度化,对农村的社会生活各方面都带来了巨大的影响。但是,任何制度都离不开现实基层的制约。当前村民自治所依赖的经济、政治、文化条件和历史传统都制约了它发挥自身的优势。因此,必须深化改革,使民主铭刻于乡村社会的内心。     

副词性确认标记词“有”的用法（下）

作为副词，“有”可以和副词、体标记、时间词、形容词等连用，也可以单独运用。通过“有”的运用，进一步验证了将“有”定位作“副词性确认标记词”的准确性。     

浅析战后东亚经济崛起的主要推动力——基于政府制度安排的视角

战后东亚地区的经济实现了快速崛起,而对于其背后的推动力却有着不同的解释。通过选取制度经济学中关于政府制度安排这一视角综合分析,东亚地区经济增长的主要推动力并非来自物质资本的投入和人力资本的扩张这些表面性因素推动,而是来自深层次的制度性因素的推动。从东亚各国、地区的历史文化背景和社会现实状况综合分析,东亚地区的经济之所以能够实现一种有魅力的增长,其主要原因就是选择了市场经济的二元调节机制这一制度安排,使政府充分发挥了促进经济有效率增长的积极作用。未来东亚地区的经济若要继续保持这一增长趋势,必须要坚持和不断完善这一制度安排。     

Influences affecting the soil-water characteristic curve

INTRODUCTION The soil-water characteristic curve (SWCC) gives the relationship between the amount of water in the soil (i.e. gravimetric or volumetric water content) and soil suction (i.e. matric suction at low suction and total suction at high suction). Many properties of a partially saturated soil such as the coefficient of permeability, shear strength and volume strain, pore size distribution, the amount of water contained in the pores at any suction, can be obtained from the SWCC. …     

New mode of universal access and Global Memory Net

INTRODUCTION During 1998~2002, I was privileged to serve as a member of the US President’s Information Technol- ogy Advisory Committee (PITAC), and all members were deeply involved in the drafting of several PITAC Reports to the President. The one related to digital libraries was the 2001 Report of the PITAC Digital Library Panel, entitled Digital Libraries: Universal Access to Human Knowledge (PITAC, 2001). It offers an ambitious vision: “All citizens anywhere anytime c…     

校本科研的尴尬与反思

新一轮基础教育课程改革对教师素质提出了新的要求,教师要适应新课改,必须要在新课程改革的不断推进中获得发展.在这种实践背景下,校本科研成了我国教育界备受关注的问题,校本科研以其多元的性格、实践的取向赢得了广大教育工作者、特别是一线教师的认同,成为教师专业发展的一条重要途径.     

教育硕士教育质量监测及其改进策略

质量是教育永恒的主题。文章针对教育硕士专业培养的现实问题,提出以学生参与为重点、以过程评价为核心、以社会评价为主体、以促进发展为目的为教育硕士培养质量监测的价值取向;坚持督和导的统一、点和面的统一、承和改的统一、知和行的统一是改进教育硕士培养质量的基本策略。     

Localized Representation of Formative Assessment in China: A Regional Study from a Sociocultural Perspective

Formative assessment originated and developed in a Western context. With its function of learning improvement being evidenced in research, formative assessment has been adopted in assessment initiatives in multiple contexts including that of China. Research, however, reveals that formative assessment as implemented in Chinese contexts is by no means equivalent to what is understood and implemented in the West; rather, in many cases, it is decontextualised and recontextualised, or culturally appropriated. This paper presents findings of a study which examined the culturally appropriated representation of formative assessment within eight universities in a mid-western province of China. Senior administrators in each university were interviewed face-to-face and individually to fulfill three purposes: (1) To clarify understandings of formative assessment in the area of college English education; (2) To explore the existing gap between formative assessment principles and their representation in College English Curriculum Requirements (CECR), and the gap between formative assessment initiatives at the national level and local contexts; and (3) To distill implications for policy-borrowing and effective implementation in the Chinese context.