变电站防雷保护

随着智能建筑系统内的电子设备的数量和规模的不断扩大,大量采用计算机技术,而电子设备普遍存在着绝缘强度低,过电压耐受能力差的弱点,当其受到电磁脉冲,特别是闪电电磁脉冲的袭击,使得这些电子系统在运行时,出现不同程度的运行故障;给工业生产以及人们日常生活造成巨大损失。因此智能建筑物系统内的防雷措施显得尤为重要。     

立井钢丝绳卡绳器移动装置的设计与应用

针对煤矿立井安装、拆除钢丝绳卡绳器时费时费力、易发生挤手碰脚现象和滑落井筒的危险,设计了卡绳器移动装置。不仅省时省力,工作效率提高2倍,安全性能大大提高。     

气垫输送机供风装置的设计

供风装置是气垫带式输送机的关键技术之一,精心搞好供风装置的设计可大大提高气垫带式输送机的技术性能,拓宽其使用范围。作者在总结多年设计供风装置成功经验和存在问题的基础上,研制成功了对称供风分风分流型供风装置。实践证明,运行效果良好,其经验可供同行借鉴。     

基于软件无线电的中频数字化直扩系统的设计与实现

本文根据直接序列扩频原理,给出了一种基于软件无线电思想的中频数字化直扩系统的设计方案,并采用可编程数字器件实现。实验结果表明该方法达到了设计要求,并具有良好的通用性和灵活性。     

Trajectories in human domination of ecosystems: Human appropriation of net primary production in the Philippines during the 20th century

The “human appropriation of net primary production” (HANPP) has been suggested as a comprehensive indicator to measure impacts of human land use on ecosystems. It accounts for (a) human-induced changes in biological productivity and (b) biomass harvest. This study presents an analysis of aboveground HANPP in the Philippines between 1910 and 2003, a period characterized by massive deforestation and increases in land use intensity and biomass extraction. Results show a steep increase of aboveground HANPP from just below 35% of potential productivity in 1910 to slightly above 60% in 1970 and constant values since then. Large-scale changes in land cover and agricultural practices were the main direct determinants of this trajectory in HANPP. Remarkably, HANPP grew at much slower pace than population did: While the amount of NPP appropriated by humans doubled throughout the period, population increased by a factor ten. Increasing efficiency in terms of biomass extraction per unit of area, relying on ever-increasing inputs, and changes in the nation's physical biomass trade balance were of major importance for this difference in growth rates. In the coming decades, the Philippines will have to face the challenge to meet increases in biomass demand without putting even higher strains on the ecosystems.     

双电源自动切换开关（ATS）在站用电系统中的应用分析

文章通过对变电站站用电系统中2种常用的备自投设备—微机型备自投装置和双电源自动切换开关（ATS）进行对比分析,阐述双电源自动切换开关（ATS）在站用电系统应用中的可靠性和简便性。     

会计计量的十大“硬伤”

会计这门经济学科是社会经济发展产物,并随着社会经济发展而发展。2008年金融危机已暴露出现行会计计量弊端,因此,在后金融危机时代,如何进一步完善、推动会计理论发展,以适应社会经济发展需要,是会计界必然面对的问题。     

PCF1536的驱动程序开发和调试

PCF1536是一个能在Windows 2000下连续输出数据的PCI卡.该文首先简要介绍PCF1536的设计原理和硬件结构,然后介绍用DriverWorks设计PCF1536的WDM驱动程序、安装文件和测试程序;最后给出测试结果.