Reexamining the effect of packet pricing in the wireless internet

In this paper, we compare the market performances of circuit pricing whereby users are charged based on their length of usage time with packet pricing whereby users are charged based on the amount of information received. We show that, if packet pricing is introduced, the market price rises contrary to a widely held belief, but that the overall social welfare is unambiguously increased. Also, we show that a move to packet pricing lowers the price of multimedia transmission which requires a much higher speed, thereby increasing the usage of multimedia data in the absence of congestion, although this may not be the case in the presence of congestion.     

寻呼机用SAW滤波器D281的性能分析

本文解剖了寻呼机用国外样管Ｄ２８１，并模拟了其衍射频响。实测结果表明，与数值模拟相符。     

绝对有源二端口网络S参数存在范围的研究

本文将给出绝对有源二端口网络S参数的存在范围。这个存在范围的边界是针对|S_(22)|,|S_(11)|平面内,散射矩阵元S_(11)和S_(22)的模的大小给出的。研究表明:在已给出S参数四个模中的三个和四个幅角的情况下,绝对有源条件通常给出散射参数的第四个模的上、下限。在文章的最后将给出一些简单的例子,以说明理论结果的有效性。     

线性多步法各系数约束条件的证明

<正> 开发高科技产品,争取从较高层次上参与国际分工和竞争,提高企业的国际经营效益已成为我国外向型经济发展中的一大目标。实现这一目标,不仅需要重视技术的研究、产品的开     

MDF列告警单元的工作原理及电路实现

本文对MDF远端集中监控系统进行了系统性概述，重点介绍了系统中列告警单元的工作原理以及电路实现。     

Innovations in Information Technology: Insights from Italian Renaissance Art

Information technologies help in defining historical eras. Innovations in information technology (IT) often lead to profound changes in social, cultural, and economic processes. Art historical approaches open up a realm of earlier forms of IT and provide productive fresh perspectives on technological innovations. Changes in image production during the Renaissance advanced possibilities for art to address or "hail" the viewer in more personal ways, implicating patrons and consumers alike within the artwork's system of meaning and value. Renaissance patrons successfully appropriated the form and symbols of religious art; contemporary corporations likewise appropriate cultural referent systems within marketing and image campaigns. By considering painting as an IT, we gain theoretical links between disparate yet interlinked cultural fields such as photography, art, marketing communications, and the Internet.     

厚膜混合集成频率合成器的可靠性增长

本文介绍厚膜混合集成频率合成器在研制与生产过程中依照“试验—分析—改进”的方法进行工作。首先预计了集成器件可能达到的可靠性水平。在初试中产品的可靠性水平较低。经过分析修改了设计方案,在试生产中可靠性明显增加,但环境试验又暴露出封装方面的问题。通过试验改进又进行高温电老化筛选,去除了早期失效的产品,经过这一系列工作后当置信度为0.8时,这批产品置信区下限估计MTBTP、已接近3000小时,通过“试验—分析—改进”的几次循环,产品可靠性增长十分显著。提交装机使用的厚膜混合集成频率合成器组件其MTBF约为7.6×10~5小时,并已超过初期预计的可靠性指标,使用反应良好。     

计算网络时域变化响应的卷积方法

本文提出了一种计算线性动态网络微分灵敏度和大变化灵敏度的统一方法。该方法编程简单、计算量小,特别适合多端口的网络。     

美国JOY公司7LS3采煤机中的电气回路保护

本文探讨美国久益 7LS采煤机先进的电气回路保护。通过电流传感器、电阻温度装置 (RTD)和牵引电机断路器 ,有效地保护电路 ,防止了过载、短路和电机过热等对生产造成的影响     

Evaluation of global models

Complicated and sophisticated global models are available and popularly used (but commonly without model evaluation procedures), and hence, the question of how one can evaluate a global model is worth being investigated. We discuss whether or not these global models together can be fully utilized and, if so, how this might be achieved.