关于有限零因子环的上界

证明了具有n(n≥2)个左(右)零因子且|R|相似文献   

对流层辐射源的体积界探讨

本文在概述对流层散射波的辐射源模型及其与功率和衰减因子的关系的基础上,着重探讨强方向性天线情形──模拟出六面体的辐射源模型,并导出其表达式。     

集料级配对二灰碎石抗压强度的影响

根据室内试验的结果，采用直观分析和方差分析方法分析了集料级配对二灰碎石混合料不同龄期抗压强度的影响。结果表明，集料级配对二灰碎石的抗压强度有显著影响；采用偏粗级配时，二灰碎石的前期强度较高，而采用偏细级配时，二灰碎石的后期强度较高；当集料不含小于0．6mm的颗粒时，存在使二灰碎石强度达到最大的集料最佳含量；间断级配时间断区段的粒径越大，二灰碎石的强度越高。     

正四面体生成的Sierpinski块的Hausdorff测度

构造了正四面体生成的一般Sierpinski块,通过构造其覆盖序列,得到了一般Sierpinski块的Hausdorff测度的上界,即ss1a22,　　Hs(V)≤61 34-2a 1657a2-121-a39a2　　(0.32≤a≤0.5).     

具非局部源半线性抛物方程变号解爆破时间的下界估计

考虑一类具非局部源半线性抛物方程Neuman边值问题解的爆破性质, 通过构造辅助函数并利用一阶微分不等式, 给出该方程解爆破时间的下界估计.     

Cramer-Rao bound of joint estimation of target location and velocity for coherent MIMO radar

The optimal estimation performance of target parameters is studied. First, the general form of Cramer-Rao bound （CRB） for joint estimation of target location and velocity is derived for coherent multiple input multiple output （MIMO） radars. To gain some insight into the behavior of the CRB, the CRB with a set of given orthogonal waveforms is studied as a specific case. Second, a maximum likelihood （ML） estimation algorithm is proposed. The mean square error （MSE） of the ML estimation of target location and velocity is obtained by Monte Carlo simulation and it approaches CRB in the high signal-to-noise ratio （SNR） region.     

考虑需求波动和产能调整成本的混流装配线平衡问题

混流装配系统面对的市场需求经常受各种因素影响而上下波动,当实际需求与预期不同时,企业需要采取加班等临时措施调整产能. 然而现有装配线平衡研究大都是按照确定的预期需求量配置的,少数考虑随机需求的研究也都忽视了平衡方案后续进行产能调整的成本和难易程度. 文章针对需求不确定环境下的混装线平衡决策,考虑了维持日常产能的人工成本和加班带来的产能调整成本,建立了数学模型,提出了一种估计总成本下界的方法并设计了启发式算法. 计算实验表明算法能在较快时间内获得较好的结果.     

Using self-location to calibrate the errors of observer positions for source localization

The uncertainty of observers＇ positions can lead to significantly degrading in source localization accuracy. This pa-per proposes a method of using self-location for calibrating the positions of observer stations in source localization to reduce the errors of the observer positions and improve the accuracy of the source localization. The relative distance measurements of the two coordinative observers are used for the linear minimum mean square error （LMMSE） estimator. The results of computer si-mulations prove the feasibility and effectiveness of the proposed method. With the general estimation errors of observers＇ positions, the MSE of the source localization with self-location calibration, which is significantly lower than that without self-location calibra-tion, is approximating to the Cramer-Rao lower bound （CRLB）.