基于UWB、ZigBee的WPAN与WLAN的干扰

目前,大量的无线设备应用在2.4GHz这一开放频段,很明显各种设备之间存在着潜在的干扰问题,在将来的办公或家庭环境中,如何避免或减少各种WPAN设备与WLAN的相互射频干扰变得日益重要。分析了分别由UWB、ZigBee技术构成的2种新型WPAN设备和WLAN之间的影响,分别从WLAN设备链路的吞吐量和信噪比(RSN)等角度分析了802.11bWLAN与2种短距离技术设备的干扰,并进行了WPAN设备的工程实验和模拟仿真。     

TCP拥塞控制机制及性能分析

随着因特网的迅猛发展,因特网中的业务量呈逐年上升趋势,研究了TCP拥塞控制机制及其提供的拥塞控制性能,特别是对TCP连接过程中的数据业务流量与丢失率和其他参数的关系进行了深入的研究。分析表明TCP拥塞控制机制可通过控制注入网络的业务流量,在一定程度下缓解网络拥塞程度,但不能实现数据的有效率的传输。     

WLAN技术对传输层性能的影响

IEEE802.11系列标准被用于支持无线局域网(WLAN)中的数据传输,而在其上层工作的传输控制协议(TCP)还是为传统有线网络传输设计的,所以TCP的性能必然会受到影响。文章首先详细阐述了在WLAN基础工作模式下的各种因素对TCP性能的影响,然后简要介绍了基于不同设计思路的改善TCP性能的方案,最后提出了一种可应用于WLAN的综合改进方案。     

Threshold-related throughput – A new criterion for evaluation of sensor network performance

Energy efficient and power aware protocols are of utmost importance in Sensor Networks. The most popular criteria so far, for evaluating performance of energy-aware protocols are lifetime and throughput. One of the main contributions of the present paper is to show that very often those criteria provide insufficient indications of the algorithm performance. Here we propose a new criterion, named threshold-related throughput, which provides a much better measure of the algorithm performance. The other main contribution of the paper is an extensive investigation of a large variety of routing protocols and routing cost metrics, activated on a variety of Sensor Network topologies, configurations and initial energy patterns. The work studies the performance of these protocols and compares them using the new criterion. In addition, we present results of an extensive investigation of performance of several configurations, heterogeneous and hierarchical, of networks with two types of devices.     

Automated parallel polyurethane dispersion synthesis and characterization

The synthesis of waterborne polyurethane dispersions (PUDs) using an automated parallel reactor system was explored. Waterborne PUDs are an important class of polymer dispersion that can be used in many applications such as coatings for wood finishing, glass fiber sizing, adhesives, automotive topcoats, and other applications. Herein, we present the synthesis of aqueous PUDs using a Chemspeed Autoplant A100™ automated parallel reactor system. This is the first time a PUD has been synthesized using an automated parallel reactor system. The synthesis involves the formation of an isocyanate-terminated prepolymer followed by neutralization, dispersion in water, and chain extension. Details of the methodology are discussed with respect to the process of writing the program for the synthesis to synthesizing the PUD itself with the Chemspeed. It is demonstrated that an aqueous PUD can be synthesized with an automated parallel process and the unit-to-unit results are similar. Process variables such as agitator design, rate of neutralization, and rate of water dispersion are varied as these are the three major factors which lead to the desired end product property. The controlled addition of neutralizer, water, and chain extender is an added advantage with this automated technique and gave consistent results in all the units. The PUDs were characterized for their particle size, viscosity, and percent solids.     

对我国加氢裂化装置消除“瓶颈”的技术路线的看法和建议

简述了我国加氢裂化装置的现状和国外加氢裂化装置消除“瓶颈”制约的范例，对我国加氢裂化装置消除“瓶颈”制约的技术路线提出了一些看法和建议。     

COMFLEX-1卷烟贮存输送系统的技术升级

由于上下游设备的升级,COMFLEX-1卷烟贮存输送系统的性能已不能满足生产需求,为此,对该设备进行了升级改造:增加缓冲区的容量以提升额定工作能力;改进物流横截面等以改善烟支质量;采用阀岛技术对气动系统进行了改进;电气系统采用了变频控制和PROFIBUS总线。升级改造后的COMFLEX-1扩大了设备的使用范围,提高了系统的生产能力及自动化水平,系统运行更加稳定和可靠。