Spreading Code Design Using a Global Optimization Method

The performance of a code division multiple access system depends on the correlation properties of the employed spreading code. Low cross-correlation values between spreading sequences are desired to suppress multiple access interference and to improve bit error performance. An auto-correlation function with a distinct peak enables proper synchronization and suppresses intersymbol interference. However, these requirements contradict each other and a trade-off needs to be established. In this paper, a global two dimensional optimization method is proposed to minimize the out-of-phase average mean-square aperiodic auto-correlation with average mean-square aperiodic cross-correlation being allowed to lie within a fixed region. This approach is applied to design sets of complex spreading sequences. A design example is presented to illustrate the relation between various correlation characteristics. The correlations of the obtained sets are compared with correlations of other known sequences.     

A New Cytotoxic Acetogenin from the Seeds of Annona squamosa

A New Annonaceous acetogenin,squamostolide(1),was isolated from the seeds of Annona squamosa.Its structure was elucidated based on spectroscopic methods and comparison with known compounds.It is the first example of Annonaceous acetogenin with each of the two ends of the aliphatic chain bearing a γ-lactone.Thenew compound exhibited cytotoxic activity in vitro against bel-7402 and CNE2 human tumor cell lines.     

制备介孔复合环境材料的酸洗刻蚀工艺

探索了一种制备介孔复合环境材料的方法--破坏式造孔与有机复合相结合,使最终产品可大量吸附污染水体中的各种污染物并具有一定的杀菌功能.该方法通过酸洗刻蚀,达到了去除原材料中的杂质和刻蚀孔径的目的,所制备的中间产品24h吸湿率为原材料的2倍,染料吸附量为原材料的1.6倍.     

汽车碰撞事故的速度分析

通过对交通事故中汽车的碰撞问题的简化 ,运用动量守恒定理和能量守恒定律着重研究了正面碰撞、追尾碰撞和侧面碰撞三种情况下 ,汽车碰撞前动量和速度的求解方法 ,为交通事故模拟和再现提供了一种更为实用的方法 ,并为科学处理交通事故、明确事故责任提供了重要参考。     

入世后西部地区如何抑制第二次人才快速外流

加入WTO后，跨国公司和东部企业为争夺人才竞相出台了优惠的政策，导致了西部地区继改革开放之后第二次人才快速外流。西部地区必须从政府宏观和企业微观两个层面着手，采取一系列积极有效的政策措施，来抑制人才的快速外流。     

有限群为ρ-幂零群的一些充要条件

在文献[1]研究Ⅱ-超中心的基础上,取Ⅱ={p},即利用p-超中心得到了ρ-幂零群的另外一些充要条件,并推广了文献[2]介绍的ITo定理.     

知识分子的批判精神和现代性危机的解决

当代西方学者正在深入讨论现代性给知识分子生活带来的深刻变化。在现代性危机状态下,反思批判性知识分子的历史使命,这对中国知识分子在现代化进程中如何履行应有的职责,不乏启发意义。     

The solution existence of general variational inclusion problems

We propose general variational inclusion problems which are slightly different from corresponding problems considered in several recent papers in the literature and show that they are advantageous. Sufficient conditions for the solution existence are established. As applications we derive consequences for several special cases of variational inclusion problems, quasioptimization problems, equilibrium problems and implicit variational inequalities and show that they improve the results of some recent existing papers.     

粗糙集理论中粗糙函数定义的改进及粗糙导数性质的证明

对二元、n元粗糙函数、k阶粗糙导数的定义进行了改进,给出了一元、二元粗糙导数的性质,并对一元、二元、n元粗糙导数的性质给出了较详细的证明.     

300kVA高温超导变压器电流引线漏热损耗的测量

电流引线是高温超导变压器的主要外部漏热来源,它的漏热量直接影响了超导变压器的经济性能,因此,引线的设计与漏热测量一直备受关注。文中构建了一个实验方案,运用量热法测量低压引线的漏热,并将试验结果与仿真预期值进行了对比和分析,从而验证了仿真设计的正确性。