时间槽在印染车间调度中的应用

面向作业调度在当今实际生产企业作业车间调度中得到普遍的应用,其基本思想是将作业一个个地安排到工作机器上。该文介绍了一种印染行业的作业车间调度模型及其处理过程,并给出了基于时间槽的求解算法。该算法通过将指定工序的可行调度起始和结束时间以逆排方式安排到有限能力的工作机器上以达到最大接近交货期的目的,通过对每一机器有效时间槽的操作来减少在每一机器上可行时间槽的搜索时间,从而提高了计算效率。     

小脑模型神经网络控制器在天线跟踪指向控制中的应用

分析了天线跟踪指向控制系统的特点和影响系统跟踪性能的主要因素,建立了系统数学模型。根据系统特点,给出了小脑模型神经网络控制器(CMAC)和PID相结合的复合自适应控制方法的设计过程,并分析了该算法适用于天线跟踪指向控制系统的优势。该方法利用传统的PID控制,结合CMAC神经网络算法的快速自学习、精确逼近的优点,既满足了天线跟踪指向控制系统快速实时跟踪的要求,又提高了跟踪精度和跟踪平稳性。仿真结果表明,该方法对摩擦力矩有很好的抑制作用,跟踪精度较单独采用PID控制提高一个数量级,且输出稳定,具有较强的鲁棒性。     

交叉极化天线阵列信道的相关性

针对符合多簇拉普拉斯分布的功率角度谱,推导了适用于均匀线阵和均匀圆阵信道相关性的闭式表达式. 该表达式反映了信道角度功率谱以及交叉极化鉴别率对信道相关性的影响. 比较了具有相同角度扩展的单簇与多簇拉普拉斯角度功率谱引入信道相关性的差异. 分析了簇内角度扩展不同时,天线阵列信道相关性随均匀线阵天线间距或均匀圆阵半径的变化. 给出了簇内平均角和簇内角度扩展分别取不同值时,信道交叉极化鉴别率对应的等效天线间距.     

前置掺气坎式阶梯溢洪道体型特点及工程应用试验研究

为了避免阶梯溢洪道中前几级阶梯表面发生空蚀破坏,将掺气坎应用到阶梯溢洪道体型设计中,形成前置掺气坎式阶梯溢洪道。这既能充分利用阶梯增加沿程消能的优点,又能扩宽阶梯溢洪道的应用范围。工程模型试验成果表明,通过掺气坎和阶梯的体型优化,各级流量的消能率均达到70%左右。1:40物理模型试验上实测溢洪道阶梯竖直面后的掺气浓度沿程分布均大于5%。研究表明这种新型阶梯溢洪道掺气量与掺气浓度易于控制,底部掺气充分,抗空蚀性能优越,消能率高,可以在高水头、大单宽流量溢洪道中推广应用。     

BP神经网络天线方向图获取方法研究

焦平面阵列成像体制是实现无源毫米波实时成像的主要途径。焦平面体制存在馈源偏焦的问题,导致成像系统的点扩展函数(PSF)具有空变特性。为研究毫米波焦平面阵列成像点扩展函数的空变规律,提出采用BP神经网络生成偏焦位置的空变方向图。通过分析天线方向图数据的特点,研究了BP神经网络的结构形式和输入输出数据格式的设计方法,并通过实验方法确定了网络的隐层形式。实验结果表明,采用双隐层BP神经网络生成的方向图可以达到99.75%的精度。     

广义分布式天线系统上行分集性能分析

针对广泛存在于无线通信环境中的阴影效应对系统性能影响非常大的问题,采用与传统的微分集技术相比,能够有效地对抗这种阴影衰落的分布式天线技术来解决这个问题.为了获得该条件下系统的理论性能,分析了采用最大比合并和相干等增益合并分集的广义分布式天线系统.借助lognormal近似法,给出了其中断概率和误码率性能的高精度解析结果.分析表明,在存在阴影衰落的情况下,这种广义分布式天线系统能够同时获得较大的微/宏分集增益,非常适合未来的无线小区环境.     

Study on the characteristics of erbium-doped waveguide ring laser

A theoretical model of the erbium-doped waveguide ring laser is established according to the theory of erbium-doped waveguide amplifier and the transmission matrix of waveguide directional coupler. The influence of bend radius, coupling coefficient and doped erbium ion concentration on the characteristics of waveguide ring laser is investigated. It is shown that due to the co-action of waveguide bend loss and other relevant loss there is an optimal bend radius which can provide simultaneously low threshold pumping power and high laser light output power. As one part of the resonator’s loss, the laser light coupling coefficient of directional coupler has an impact on the laser property. The analysis indicates that the laser achieves the high output power when the coupling coefficient is about 0.2. The threshold pumping power is the minimum when the doped erbium ion concentration is 0.85×10²⁶ m⁻³. Increasing the concentration of doped erbium ions will enhance the output power of laser light as long as the concentration doesn’t introduce remarkable up-conversion effect. The results give a good theoretical basis for the design and fabrication of erbium-doped waveguide ring laser devices. Supported by the National Natural Science Foundation of China (Grant No. 60807015), the Specialized Research Fund for the Doctoral Program of Higher Education (Grant No. 200801411037), the Young Teacher Cultivation Foundation of Dalian University of Technology (Grant No. 893210) and Doctor Start-up Foundation of Dalian University of Technology (Grant No. 893322)     

Analytical solution of electromagnetic field generated by induction logging tool in a fan-ring slot of drill collar while drilling

Based on the structural characteristic of metal drill collar for induction logging while drilling, we have given the analytical formulae of lengthways fields E _z and H _z when the tool is located in a fan-ring shaped slot of drill collar by the boundary conditions of electromagnetic field, and derived the other components of electromagnetic field in and out the fan-ring slot from E _z and H _z . In the other intervals of formation, where the drill collar is a solid cylinder, the analytical formulae of field are educed through the method of variable coefficient. The total analytical solutions of field in whole space have been obtained. With the help of the analytical formulae, we have also given numerical examples and analyzed the distributive characteristic of electromagnetic field. From the computational results we find that the secondary scattering field H _z is in a linear relation with the conductivity of stratum. The characteristic of field is very useful for induction logging while drilling, which can be used to measure and analyze the logging responses of the stratum conductivity. This paper sets up a theoretical foundation for us to study the distrbutions of field and to direct the design of logging instruments. Supported by the National Natural Science Foundation of China (Grant No. 10705049), the Beijing Natural Science Foundation (Grant No.1083011) and Funding Project for Academic Human Resources Development in Institutions of Higher Learning [PHR(IHLB)]     

300t精炼钢包透气砖应用的数学物理模拟

针对300t精炼钢包,在LF设备电极位置与钢包透气砖所在位置的对应关系确定的基础上,通过水模、数模分别采用单吹、复吹时钢包内钢水流动特性和夹杂物去除的对比研究,探讨了透气砖结构性能的影响作用。结果表明,单吹时应使用抗渗透较好且能形成有利于夹杂物去除的气泡形态狭缝式透气砖（PBI）,吹气卷渣临界气量为1．45m^3／h,气量需稳定,混匀时间为82．44s,钢液渗透小,夹杂物去除率为62．86％,能够满足搅拌钢液起到成分和温度的快速均匀以及净化钢液的作用。     

A novel initial ranging algorithm for OFDMA systems using smart antenna

To improve the capacity of initial ranging （IR） users simultaneously accessing into network and enhance the performance of the IR, a novel IR algorithm is presented for the orthogonal frequency division multiple access systems with the smart antenna. The beamforming weight vectors provided by the antenna array are introduced for the IR users, and the procedures of the multiuser parameter estimation and the interference cancellation are designed. The proposed method can improve the accuracy of the channel estimation of active paths and efficiently reduce the residual multiple access interference. Simulation results show that the proposed method has a much better performance than the available successive multiuser detection and interference cancellation algorithm and accommodates more active ranging users simultaneously accessing into a cell.