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81.
讨论一类中立型时滞偏差分方程T(V1,V2)(Bm,n-cBm-τ,n-σ)+Pm,nBm-k,n-t=0的振动性。得到了该方程所有解振动的充分条件,获得了新的结果.  相似文献   
82.
The electric field integral equation (EFIE) combined with the multilevel fast multipole algorithm (MLFMA) is applied to analyze the radiation and impedance properties of wire antennas mounted on complex conducting platforms to realize fast, accurate solutions. Wire, surface and junction basis functions are used to model the current distribution on the object. Application of MLFMA reduces memory requirement and computing time compared to conventional methods, such as method of moment (MOM), especially for the antenna on a large-sized platform. Generalized minimal residual (GMRES) solver with incomplete LU factorization preconditioner using a dual dropping strategy (ILUT) is applied to reduce the iterative number. Several typical numerical examples are presented to validate this algorithm and show the accuracy and computational efficiency.  相似文献   
83.
基于共生理论的物流金融价值增值作用分析   总被引:4,自引:0,他引:4  
借用共生理论中共生介质的概念,说明物流金融在制造企业和物流企业共生关系中的介质作用,即其对两者共生关系中物质流、资金流、信息流的整合效果,说明价值增值是共生系统能量增长的一种表现形式.结合波特的价值链模型,分别论证了物流金融对制造企业和物流企业及它们所形成的共生系统的价值增值作用,阐明了价值增值主要源于风险成本的降低及新服务业务的利润增加.研究表明物流金融之于制造企业和物流企业走向对称互惠共生模式的必不可少的介质.  相似文献   
84.
研究在流动氮气和埋炭条件下铝热还原氮化TiO2的反应过程,借助于X射线衍射(XRD)和扫描电子显微镜(SEM)分别测试和观察两种气氛中不同温度下处理后产物的物相组成和显微结构。结果显示,与流动氮气氛下一样,在埋炭气氛下采用铝热还原氮化法可以制备氮化钛复相材料,但处理气氛明显影响着铝热反应的程度及产物的形貌,在埋炭条件下处理后的产物中氮化钛含量、晶粒大小、晶格常数明显低于流动氮气氛下处理产物中上述各项值;热力学计算发现埋炭条件下铝除参与铝热还原反应外,还与炭粉床中氧发生反应,使参与铝热反应的金属铝不足,造成产物中有剩余的金红石存在。  相似文献   
85.
An experiment was conducted using event-related potentials to investigate the old/new effects of the item recognition and the voice source retrieval tasks on drawing. The results indicated that (1) the old/new effect for the voice source retrieval task was much wider than that of the item recognition task; (2) the distributive characteristics of the voice source memory effect were different from those in previous studies; (3) the old/new effects for target and non-target-old drawings were similar. These results demonstrated that the voice source retrieval task is more difficult than the item recognition task for drawing, which supports the dual-process model. The experimental material and the source characteristic regulate the spatial and temporal distributions of the old/new effect for the voice source retrieval task together.  相似文献   
86.
Caching is an important technique to enhance the efficiency of query processing. Unfortunately, traditional caching mechanisms are not efficient for deep Web because of storage space and dynamic maintenance limitations. In this paper, we present on providing a cache mechanism based on Top-K data source (KDS-CM) instead of result records for deep Web query. By integrating techniques from IR and Top-K, a data reorganization strategy is presented to model KDS-CM. Also some measures about cache management and optimization are proposed to improve the performances of cache effectively. Experimental results show the benefits of KDS-CM in execution cost and dynamic maintenance when compared with various alternate strategies.  相似文献   
87.
In order to understand the genomic changes during the evolution of hexaploid wheat, two sets of synthetic hexaploid wheat from hybridization between maternal tetraploid wheat (AABB) and paternal diploid goat grass (DD) were used for DNA-AFLP and single strand conformation polymorphism (SSCP) analysis to determine the genomic and genic variation in the synthetic hexaploid wheat. Results indicated that more DNA sequences from paternal diploid species were eliminated in the synthetic hexaploid wheat than from maternal tetraploid wheat, suggesting that genome from parental species of lower ploidity tends to be eliminated preferentially. However, sequence variation detected by SSCP procedure was much lower than those detected by DNA-AFLP, which indicated that much less variation in the genic regions occurred in the synthetic hexaploid wheat, and sequence variations detected by DNA-AFLP could be derived mostly from non-coding regions and repetitive sequences. Our results also indicated that sequence variation in 4 genes can be detected in hybrid F1, which suggested that this type of sequence variation could be resulted from distant hybridization. It was interesting to note that 3 out of the 4 genes were mapped and clustered on the long arm of chromosome 2D, which indicated that variation in genic sequences in synthetic hexaploid wheat might not be a randomized process.  相似文献   
88.
用正交试验法优选铸钢用新型保温补贴的配方,研究其制作工艺,测试了原材料 的性能,初步探讨了保温补贴的尺寸设计,并编制了计算机辅助设计程序。通过生产 试验证明,新型保温补贴具有很好的保温性能和足够的耐火度,高达1750℃,而且 生产成本低、工艺简便,使用中获得满意结果。  相似文献   
89.
聂钧 《太原科技》2001,(4):33-33,35
在电视摄像中,光的色温和照度对色彩还原起着决定性的作用。通过理论分析,阐述了色温和照度是如何影响色彩还原的,同时提出了正确的用光方法,为达到理想的电视艺术效果,讲述了一些用光技巧。  相似文献   
90.
Co2+:ZnSiF6·6H2O的g因子随压力变化的研究   总被引:2,自引:0,他引:2  
通过Co2+:ZnSiF6·6H2O的g因子随压力变化的实验数据和晶体结构数据,确定了以压力作为参量的状态方程,并采用完全对角化方法,研究了Co2+:ZnSiF6·6H2O的g因子随压力变化的行为,理论结果和实验值符合得很好.  相似文献   
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