基于单片机的高精度快速积分型AD转换器

针对现有积分型AD转换器存在转换速率较低的问题,提出了一种基于单片机的高精度快速积分型AD转换器的设计方案,详细介绍了AD转换的实现过程。该转换器采用单片机产生各种控制信号,保证了测量过程的精确同步,提高了AD测量结果的稳定性,最快转换速度可达500次/s。实际应用表明,该转换器转换速度快,测量精度高,达到了预期效果。     

光纤到户（FTTH）的ODN工程设计及测试

文章针对PON系统的基本保护要求,提出了光分路器（OBD）设计原则;采用最坏值法对PON系统最远的用户终端,进行ODN光通道衰减核算;同时,对ODN光缆线路进行分段衰减测试和全程衰减测试,测试结果满足FTTH系统工程规范。根据现场试验的研究和测试结果,规范光纤到户（FTTH）工程系统的规划、设计、施工、监理及竣工验收等工作。     

Heterodyne mixing and polarization diversity techniques in radio over fiber system with high sensitivity and dispersion tolerance

We propose and experimentally demonstrate the heterodyne mixing and polarization diversity tech- niques in radio over fiber (ROF) systems with the advantages of high sensitivity and dispersion endurance. The generation of 2.5 Gb/s optical DPSK and PSK signals, fiber propagation and wireless transmission over 15 GHz subcarrier are illustrated with very low sensitivity of -26 and -32 dBm, respectively. Moreover, based on the wireless polarization diversity techniques, we successfully performed the t...     

光进铜退的网络信息安全建设

光进铜退是中国固网运营商中国电信和中国网通为逐步实现光纤接入(FTTx),用光纤代替铜缆所提出的一项工程——中国固网运营商现在所采用的ADSL接入网一般都是局端集中方式,即用户家ADSL Modem需要同电信分局的ADSL局端设备同步信号,这段距离一般超过3公里。这样,距离成为了国内ADSL技术提速的最大问题。所以,"光进铜退"的策略就是将FTTx技术同ADSL技术相结合,尽可能缩短ADSL局端设备(DSLAM)同用户家这段铜线的距离,以提供高带宽接入。     

全光纤安防系统模式识别及混合编程

介绍了全光纤监控预警系统及其模式识别算法。利用小波包分解对信号提取各频段内信号分量能量谱作为特征向量;应用速度与精度均非常出色的RBF神经网络实现信号分类,提高网络泛化能力。利用MATLAB引擎、组件对象模型(COM)两种混合编程方法实现将MATLAB算法程序集成到VC编写的系统平台中。使用文本文件存取网络数据,克服了MATLAB无法编译神经网络工具箱函数的缺陷,并从操作复杂度、执行时间、消耗内存等方面对两种方式进行对比,最终选定组件对象模型作为系统应用方案。     

Flicker visibility and related visual discomfort in 3‐D displays with LED backlight

Abstract— In this paper, the perception of flicker in time‐sequential or field‐sequential 3‐D LC TVs driven by LED backlights is described. The seriousness of the perceived flicker and its influence on visual discomfort is investigated for various backlight operational modes. Results show that display backlights presenting different temporal light distribution have significant contribution to flicker visibility and visual discomfort. The display dimension, 2‐D or 3‐D, affects visual discomfort but not flicker visibility. The relationship between visual discomfort and flicker visibility is proportional when rendering 2‐D images, but not in the case of 3‐D images. Finally, a simple model is presented to evaluate visual discomfort related to flicker in 2‐D rendering.     

IEEE 802.16e节能类型III的性能分析

基于IEEE 802.16e节能类型III的工作原理,考虑用户触发数据的无后效性,建立一个带有多重休假的Geom/G/1排队模型。利用嵌入式马尔可夫链方法推导出该排队系统的稳态指标,相应给出数据帧平均响应时间、能量节省率等性能指标的表达式。构造一个综合考虑能量节省与系统响应时间的成本函数,通过数值例子说明系统性能指标对休眠窗口长度的依赖关系,给出不同负载下休眠窗口长度的最优值。     

检测石油管道冰堵与定位的光纤传感器的研究

寒冷地区成品油管道冰堵现象时有发生.利用分布式光纤传感器检测管道沿途发生的冰堵信息;利用具有表征信号局部特征能力韵小波分析的方法确定光纤两端2个测试信号的时延,进而即可确定冰堵点的位置.阐述了其测试原理和堵塞点定位方法,理论分析和仿真实验结果表明:该方法可以有效提高管道冰堵测试的灵敏度和定位精度.     

反馈电路的判别

反馈在电子电路中的应用非常广泛,如何正确判断反馈类型,是分析电子电路性能的重要前提。通过结合实例就反馈类型的判别做了较为深入的分析,总结了不同电路反馈类型简单有效的判别方法,有助于初学者更好更快的掌握反馈的知识。     

The Effect of Product Type on Consumer Preferences for Website Content Elements: An Empirical Study

This study attempts to demonstrate empirically how the importance of website content in online purchasing varies across 2 product categorizations: goods versus services and hedonic versus utilitarian products. We conducted an experiment that showed that when purchasing services, customers value evaluative elements and risk‐reducing content, while consumers buying goods may be satisfied with fewer features. In addition, selling hedonic products could be more effective when focusing on large and unique assortment. Websites selling utilitarian products, on the other hand, may profit from investing in instrumental website content. The study validates the guiding role of product type in website design, and suggests that incorporating product tactics into design likely contributes to the development of websites tailored to specific consumer groups.