多种网络业务并存的IEDF算法研究

文章以EDF算法为基础,提出一种改进的调度算法IEDF。在IEDF中,提出一种新的带宽调度策略,并在3种具体情况下进行业务流调度过程分析。同时,在SIM环境下进行仿真实验,仿真结果表明,和原EDF算法相比,IEDF算法有效保证了带宽,降低了时延,提升了Qos。     

前向抽运双级双程掺铒光纤宽带光源

提出并实现了一种前向抽运双级双程结构的 1 5 5 μm超荧光光纤光源(SFS)。通过恰当地选择光源的各个参数,包括两段掺铒光纤(EDF)的长度和两级抽运光的功率,在保证平均波长稳定的情况下,获得了同时具有大功率和宽带特性的超荧光输出。这种结构的光源可以很好地满足高精度光纤陀螺(FOG)对光源的要求     

面向数据流的嵌入式系统中缓存需求量与反应时间的同步优化

同步数据流图(SynchronousDataflowGraph,SDF)是一个在嵌入式系统设计中应用很广泛的模型。基于该模型人们设计出了多种调度算法,针对信号处理领域中的实际问题作了大量的优化工作,提高了系统的性能。但是原先存在的调度算法是分别以缓存优化,或者反应时间优化为其优化目标,从而导致了一些矛盾结果:比如说减少缓存需求量的同时,增大了反应时间;又或者减少反应时间的时候,增大了缓存的需求量。而该文在EDF(最早最终期限优先算法,一种反应时间优算法)的基础上,不以增大系统优化后的反应时间为代价,进一步对其缓存进行优化。从而达到在减少系统反应时间的同时,也能够减少实际的缓存开销的目的。     

实时系统中传统调度方式的一种改进方法

介绍了在实时操作系统(RTOS)中两种典型的调度算法,速率单调调度(RMS)算法和最早死线优先(EDF)调度算法。指出了传统实时系统中调度机制的不足之处,给出一个通用调度框架模型(GSF)。该模型将调度器分成事务分派器和事务调度器两个部分,事务分派器根据任务的需求设置相应的属性,而事务调度器则根据任务的属性决定采用哪种调度算法。该模型使得调度更加灵活、有效。     

基于边缘分布函数的车道标识线识别方法

为了得到较理想的车道标识线的边缘,考虑车道标识线的方向特性,提出一种基于边缘分布函数（EDF）的图像预处理方法。将图像分区处理,在对图像中的噪声特性进行EDF分析的基础上,对处理区域作如下处理：首先将梯度角量化为4-方向,去除与车道标识线方向不一致的噪声,得到边缘图像;然后利用EDF对边缘图像滤波,确定车道标识线角度初值;最后应用Hough变换定位出车道标识线。实验结果表明,该方法能够更加有效地强化车道标识线信息,去除噪声,具有较好的鲁棒性和实时性。     

基于自反馈光注入结构的双波长可调谐掺Er3+光纤激光器

为了实现可调谐双波长激光输出,提出并设计了一种基于自反馈光注入结构的掺Er3+光纤(EDF)激光器,并对激光器的基本原理及实现方案进行了理论分析和实验验证。系统结构设计采用976nm波长的LD作为泵浦源,结合EDF,两支光纤布拉格光栅(FBG)和光纤环形镜(FLM)产生激光,并通过在FLM中熔接饱和吸收体(SA)起到稳频作用;将FLM输出激光耦合进入谐振腔形成自注入结构,与腔内振荡激光形成干涉,抑制模式跳变;通过控制两支FBG之间的可调谐衰减器调节谐振腔内的增益和损耗,实现单个波长或双波长输出。实验结果表明:SA长采用4m、EDF长采用6m时,激光输出阈值为28mW,将反馈光注入谐振腔后,系统阈值为25mW,输出激光波长随时间漂移得到明显抑制;当泵浦光功率为80mW时,通过调节位于两支FBG之间的可调谐衰减器(VA)获得稳定的双波长激光输出;随着泵浦功率增加,激光输出功率具有良好的线性度和稳定性。在1 540nm波长处激光输出最大功率为1.16mW,信噪比(SNR)大于50dB;在1 545nm波长处激光输出最大功率为1.89mW,SNR大于50dB。     

On overload control of parlay application server in next generation network

After analyzing the features of the Parlay application server（AS）, which provides many services with different time constraints in the next generation network（NGN）, a selfadapted overload control algorithm implemented in Parlay AS is proposed. In this algorithm, the service process module in parlay AS uses the earliest deadline first （EDF） serving rule to serve messages, and the overload control mechanism, using the Leaky Bucket algorithm to control message flows, is triggered by estimating the queue waiting time of a newly arriving message. By simulation it shows that this algorithm is a simple, easy-to-use, and available algorithm.     

地震卓越频率(EDF)对主动调谐质量阻尼器抗震控制设计的影响评价

基于Kanai-Tajimi地震动模型，建立了设置主动调谐质量阻尼器(ATMD)结构的传递函数。于是，ATMD最优参数的评价准则定义为：设置ATMD结构的最大动力放大系数的最小值的最小化。ATMD有效性的评价准则定义为：设置ATMD结构的最大动力放大系数的最小值的最小化与未设置ATMD结构的最大动力放大系数之比。ATMD冲程的评价准则定义为：ATMD的最大动力放大系数。基于选择的评价准则，研究了地震卓越频率(EDF)对ATMD在控制结构位移响应时的最优参数、有效性和冲程的影响。     

The Role of the Liquid-Solid Interface in the Preparation of Supported Catalysts

The contribution of the Interface Science to the preparation of supported catalysts during the last two decades is presented. It is illustrated how the concepts and the methodologies of the Interface Science could be effectively used for an in-depth understanding of the phenomena involved in the initial preparation step. This, extremely critical step, concerns the deposition of transition metal species containing the active elements, from an impregnation solution, onto the surface of common catalytic supports. Moreover, the aforementioned concepts and methodologies allow the regulation of the mode of interfacial deposition and the local structure of the deposited species and, thus, the surface characteristics and the catalytic behaviour of the resulted catalysts.     

Data Transfer for HIPERLAN

HIPERLAN offers a high speed (23.5 Mbit/s) radio LAN and therefore HIPERLAN is likely to support various kinds of traffic requirements. A Data Transfer function is in charge of handling various traffics which can result in simultaneous services. HIPERLAN nodes are not necessarily within direct radio range; and in some cases packets are forwarded by intermediate stations from the source node to the destination node. Since HIPERLAN is more than a single hop network, the support of specific traffics like Time Bounded traffics require a dedicated architecture which can not be centralized. This paper describes the architecture of the Data Transfer in HIPERLAN which allows the support of various traffics. This approach is not based on a connection oriented protocol nor on a centralized architecture but on a connection-less mode where users provide quality of services parameters to indicate its requirements. HIPERLAN architecture for data transfer is based on a mix of two main mechanisms: hierarchically independent priority levels and an earliest dead line first algorithm. This paper describes and explains the architecture choices made in HIPERLAN. Results of simulation and analytical models are given.