基于BUCK电路半导体激光电源设计

文章通过对半导体激光器特性分析,结合驱动电源的要求,研究设计了一种基于BUCK电路控制的恒流小功率高稳定半导体驱动电源。主要以UC3854芯片调节占空比来控制输出电流,针对输出电流进行PI调节,从而实现了驱动电源的精度控制,进而控制半导体激光器的输出功率。同时,采用可靠的保护措施,通过温度传感器、过流过压保护电路对半导体激光器进行实时检测,从而保证在激光输出过程可靠、安全、稳定。     

一种小功率LED驱动电源的设计与实现

为了保证小功率LED发光的高效性和均匀性,需提高驱动电源的性能。本文采用电容降压、桥式整流的方法针对LED交叉阵列连接方式设计了一种驱动电路,经仿真实验验证本驱动电路可靠性较高,实用性较强。     

低功耗LED驱动电源设计

LED照明(SSL:Solid State Lighting)为全世界用户提供了新的照明产品。LED必须有独立的驱动电源才能使其点亮发光。LED替代传统照明成为一种趋势,如果降低LED成本,降低LED功耗更是顺利替代传统照明的一条捷径。本文通过对各种拓扑结构的分析和选择,从而选择驱动芯片,最后以具体驱动芯片为案例,详细介绍低功耗LED驱动器的设计方法。     

一种新的汽车前照灯驱动电路设计

LED作为一种新型照明光源,具有发光效率高、寿命长、显色性好、绿色环保、不易破损且易于进行数字控制等优点。采用PT4107芯片设计的LED汽车前照灯驱动电路,解决了车用电压不稳定的问题,电路具有输出电流稳定、精度高、驱动器效率高的特点。     

FAN6961在LED路灯驱动电源中的应用

LED驱动电源通常采用全桥整流和电容滤波电路实现AC／DC的变换，线路中会产生谐波干扰和波形的失真，这将对电网和线路产生严重的干扰，影响电源的利用率。本文将飞兆公司生产的芯片FAN6961应用于一款智能型LED路灯驱动电源中，较好地实现了功率因数校正，使驱动电源的性能得到较大提升。     

LED驱动电源在设计应用中容易忽视献技术问题及检验方法

介绍了LED驱动电源在设计和实际应用过程中,容易被忽视,却能够对LED照明灯具可靠性产生负面影响的技术问题,并为如何选择LED驱动电源提出了相应的检测检验方法,为LED驱动电源在今后的设计和推广应用提出了建设性的指导意见。     

单色PMOLED电源及屏显驱动电路设计

文章设计了一种基于ISL97702的便携式产品的DC/DC直流升压电源电路,输入电压2.3～5.5V,输出电压根据负载轻重在2～30V范围内可调;OLED显示驱动采用PT6807和PT6808构建的无源矩阵驱动方式,适用于单色小尺寸OLED的显示驱动。     

单色PMOLED电源及屏显驱动电路设计

文章设计了一种基于ISL97702的便携式产品的DC/DC直流升压电源电路,输入电压2.3～5.5V,输出电压根据负载轻重在2～30V范围内可调;OLED显示驱动采用PT6807和PT6808构建的无源矩阵驱动方式,适用于单色小尺寸OLED的显示驱动。     

射频接收芯片中CMOS晶体振荡器的设计

本文采用0.18um CMOS工艺设计了一种应用于射频接收芯片的4MHz的Pierce晶体振荡器,采用自动增益控制(AGC)结构,提高了频率稳定性,降低了功耗。流片测试结果显示,在1.8V电源电压下,输出频率具有较好的精度,最大的频率误差为0.1%,在1.8V电源电压下,消耗电流500 nA,版图面积为100um×250um,满足射频收发芯片低功耗、高稳定性、和版图面积小的要求。     

室外大屏幕LED矩阵显示系统的抗干扰设计

室外大屏幕LED矩阵显示系统的抗干扰设计采用了7个抗干扰、低功耗的PIC16F1937单片机组成级联电路,具有恒流输出的TB62726型16位移位锁存器和HF3009恒流驱动电路构建了行、列双路恒流的LED矩阵驱动电路单元。并通过防静电、抗电磁干扰能力的设计,使大屏幕LED显示系统运行可靠。     

Development in Information and Communications Technology (ICT) Statistics at the Australian Bureau of Statistics

This paper outlines the ICT statistical developments that the ABS has undertaken over recent years. These developments have been on both the supply side (ICT industry) and the demand side (use of IT by sector). The content of ABS ICT surveys has changed significantly over the last few years and are expected to develop further in line with industry changes and emerging policy needs.
Recent developments in household collections have been the inclusion of IT use questions in the 2001 Census of Population and Housing and in various ABS social surveys such as Children's Participation in Culture and Leisure Activities. Annual business IT use surveys are now conducted and include topics such as Internet commerce and IT security. Biennial ICT industry surveys are conducted to provide data on ICT production, imports and exports, ICT industry employment, performance and structure information. An Internet activity survey is run every six months and provides regional Internet access details and infrastructure details on Internet service providers.
A major development for 2002–03 will be the compilation of an ICT satellite account. ABS intends to produce an ICT Information Development Plan to guide its future statistical development work in the ICT field.     

Value at Risk in the Suburbs: Eminent Domain and the Geographical Politics of the US Foreclosure Crisis

Several US counties and local governments have recently considered a novel solution to the foreclosure crisis. They plan to use eminent domain to compel the owners of mortgage debt—and specifically of private‐label mortgage‐backed securities—to sell the debt to the government at a price reflecting the loan's market value. The government would then restructure the debt and resell it to new investors. The plans are striking because—in contrast to both development‐driven eminent domain and the federal subprime bank bailout—they would force investors to assume asset devaluation and increased long‐term risk. Notably, the plans have emerged as an instance of financialization‐focused politics in suburbs and suburban cities of color, specifically majority‐black and ‐Latino/a suburbs. Local support for the plans, we argue, is rooted in the long‐term disinvestment of these ‘suburbs of exception', which became targets of subprime lending and eventually sites where the ‘financial exception' has been localized. But these demographic shifts, fragmentation and fiscal pressures have at the same time created a suburban political terrain in which the plans have gained their strongest political support.     

Towards a Theory of Serendipity: A Systematic Review and Conceptualization

Serendipity – the notion of making surprising and valuable discoveries – plays a major role in the success of individuals and organizations alike. Previous research has established the importance of serendipity and identified important individual- and organizational-level antecedents. However, the literature has been dispersed and the boundaries of the concept have been blurry, leading to a lack of conceptual clarity and structure, and thus limiting validity and managerial actionability. Based on a systematic literature review, I synthesize existing management-related research on serendipity and explicate the emergence and composition of serendipity in the organizational context. I first identify three necessary conditions that differentiate serendipity from related concepts such as luck or targeted innovation: agency, surprise, and value. Then, I draw from the literature on sensemaking, event-based theorizing, and quantum-based approaches to management to conceptualize the process of cultivating serendipity in the organizational context as a process of enabling potentiality and materialization, and develop a multi-level theory of (cultivating) serendipity. This conceptualization contributes to our collective understanding of how, why, and when (i.e., under what conditions) organizations can leverage the value in the unexpected, which opens up fruitful avenues for further research.     

Accountability of NGOs in Bangladesh A critical overview

NGOs in Bangladesh have been recognized as effective change agents in the socio-economic arena throughout the world. Their contributions in micro credit, non-formal education and primary health care are widely known. NGOs play a significant role in society. NGO accountability, as a result, has become a critical issue. NGO accountability in Bangladesh has been examined here in relation to patrons, clients and themselves. Of the three relationships only accountability to patrons is in a near satisfactory state. Accountability to clients is handicapped by lack of opportunities of beneficiaries to participate meaningfully in NGO policy making. Accountability to themselves is adversely affected due to the adherence to a strictly hierarchical system and the influence of founding and charismatic NGO leaders.     

Towards an Asian model of human resource management? A comparative analysis of China,Japan and South Korea

There has been much discussion regarding the possible decline and weakening of national systems of human resource management (HRM). Yet, culture and institutions are often cited as the major stumbling blocks to this outcome. Such constraints may dissipate in the analysis, particularly if ‘regional clusters’ are considered where geographic and cultural closeness and ‘openness’ to similar economic pressures exist. In such cases, it might be postulated that convergence in HRM will occur. We argue that China, Japan and South Korea represent such a cluster. This article examines these countries, to see if a degree of convergence is taking place and if it is towards an identifiable ‘Asian’ model of HRM. A model of change is presented that distinguishes between levels of occurrence and acceptance. Details of the development and practice of HRM in each country are then set out. The article ends with a discussion and implications section and a brief conclusion.     

The Creation of the Office for National Statistics

A new Office for National Statistics was created in the United Kingdom in 1996 following a series of developments designed to strengthen the relevance and integrity of statistics. This paper describes these fundamental changes and sets out a blueprint for future progress. It also sets current developments in the United Kingdom in an historical and international context.     

What helps? Women engineers' accounts of staying on

We have considerable understanding of the obstacles that women engineers encounter and the reasons that they leave the field, but we know less about what enables them to remain. Adopting an interpretivist approach, this article examines how a group of British women engineers in two FTSE 100 companies account for “staying on” in their male‐dominated work settings. We delineate four specific forms of help that facilitate women's retention in the field. We argue that exposure to help leads to women developing a habitus that enables them to continue working in engineering. To conclude, we draw on our findings to outline HR practices that will facilitate supportive relationships in the workplace and pave the way towards developing more positive organisational climates.     

论现代物流企业的发展观

物流业经过诸多年的发展目前已经成为最热门的行业之一,物流企业的注册数量也与日俱增,达到前所未有的规模。毋庸置疑,任何企业都希望自己迅速做强做大,并成为真正现代物流企业的典型代表,要实现这一目标一个首要问题就是要解决现代物流企业的发展观问题。     

浅谈大体积混凝土裂缝的控制

大体积混凝土的裂缝问题是实际工程中长期困扰工程技术人员的问题,其控制技术的研究是混凝土结构研究的热点问题,具有重大的学术价值和潜伏的工程背景。     

Supply Chain Strategies in the UK Fashion Industry—The Rhetoric of Partnership and Realities of Power

This paper focuses on the fashion industry, one characterised by issues such as dramatic shifts in the scale and power of major retail buyers in the market, the advent of retailer own brands, and the nature of sourcing and supply chain decisions, issues that are increasingly global in nature. The aim of this research is to explore the nature of relationships between UK high street multiple fashion retailers and their contracted suppliers, many of whom are entrepreneurial firms by most definitions of the term. Four core themes emerge from the literature and provide a framework for the research, namely, power, process, partnership, and people. The research approach was qualitative, and conducted over a period of twelve months. The paper ends with an agenda for future research.