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1.
In cellular networks, QoS degradation or forced termination may occur when there are insufficient resources to accommodate handoff requests. One solution is to predict the trajectory of mobile terminals so as to perform resource reservations in advance. With the vision that future mobile devices are likely to be equipped with reasonably accurate positioning capability, we investigate how this new feature may be used for mobility predictions. We propose a mobility prediction technique that incorporates road topology information, and describe its use for dynamic resource reservation. Simulation results are presented to demonstrate the improvement in reservation efficiency compared with several other schemes.  相似文献   
2.
北京火车站抗震鉴定与加固技术   总被引:5,自引:3,他引:2  
北京火车站是首都重要的标志性建筑之一 ,195 9年建成 ,当时按 7度设防考虑 ,存在着许多不符合抗震要求的问题 ,一些设施也明显不能满足现代使用功能要求。北京火车站抗震加固与改造设计项目组 ,运用多种先进的加固手段 ,在保持原建筑外貌不变的前提下 ,实现了抗震能力和改善使用功能的协调 ,取得了大型公共建筑加固改造的新经验  相似文献   
3.
By using a mRNA differential display technique to search for salicylate suppressible genes, we identified a cDNA in human foreskin fibroblasts, which by GenBankTM DNA data base search shows sequence homology to the recently reported cullin/Cdc53 (CUL) family genes, especially CUL-3. We have cloned the full-length human CUL-3 (Hs-CUL-3) cDNA. It encodes a 768-amino acid polypeptide and has a predicted molecular weight of 88,939. The amino acid sequence of Hs-CUL-3 shows 46% homology to that of its Caenorhabditis elegans ortholog, Ce-CUL-3, and 27 and 23% to that of Hs-CUL-1 and Hs-CUL-2, respectively. Northern blot analysis showed that phorbol 12-myristate 13-acetate increased the expression of Hs-CUL-3 mRNA in a concentration- and time-dependent manner, and this increase was inhibited by sodium salicylate. Hs-CUL-3 widely expressed in human tissues and its expression in cultured COLO205 colon cancer cells was increased when compared with that in normal colon cells. It is likely that Hs-CUL-3 is involved in cell proliferation control.  相似文献   
4.
正交曲线坐标下三维代数应力通量模型   总被引:7,自引:1,他引:6  
针对弯曲及不规则明渠的水动力及物质输运特性,本文建立了曲线坐标系下的三维代数应力通量数学模型,对平面上弯曲及不规则复杂边界情形,采用Poisson方程进行正交曲线坐标变换,各向异性的湍流代数应力通量模型被引用于本文的模拟计算中,以体现复杂边界条件引起的水动力及物质输运特性的变化。通过180度强弯曲明渠水槽及贵溪电厂不规则边界河段物理模型试验两个实例计算表明,实测值与计算吻合良好,效果令人满意。  相似文献   
5.
Given a stability region of a polytope of polynomials, the edge theorem can be used to verify certain root-clustering properties of the polytope. The authors consider the inverse problem; starting with a polytope of real polynomials, they present a result that allows the construction of the smallest set of regions in the complex plane which characterizes its zero location  相似文献   
6.
Closed laboratories are becoming an increasingly popular approach to teaching introductory computer science courses. Unlike open laboratories that tend to be an informal environment provided for students to practice their skills with attendance optional, closed laboratories are structured meeting times that support the lecture component of the course, and attendance is required. This paper reports on an integrated approach to designing, implementing, and assessing laboratories with an embedded instructional research design. The activities reported here are parts of a departmentwide effort not only to improve student learning in computer science and computer engineering (CE) but also to improve the agility of the Computer Science and Engineering Department in adapting the curriculum to changing technologies, incorporate research, and validate the instructional strategies used. This paper presents the design and implementation of the laboratories and the results and analysis of student performance. Also described in this paper is cooperative learning in the laboratories and its impact on student learning.  相似文献   
7.
取代二苯多烯和取代聚二乙炔的三阶非线性光学性质   总被引:1,自引:0,他引:1  
为了设计新的具有较高非线性极化率和光损耗小的有机非线性光学(NLO)材料,需要了解不同的有机结构对分子非线性的影响。在此基础之上,建议用平行对比的方法来近似估算取代二苯多烯和聚二乙炔(PDA)的三阶非线性光学极化率。  相似文献   
8.
Groups of algebraic integers used for coding QAM signals   总被引:2,自引:0,他引:2  
Linear block codes over Gaussian integers and Eisenstein integers were used for coding over two-dimensional signal space. A group of Gaussian integers with 22n elements was constructed to code quadrature amplitude modulation (QAM) signals such that a differentially coherent method can be applied to demodulate the QAM signals. This paper shows that one subgroup of the multiplicative group of units in the algebraic integer ring of any quadratic number field with unique factorization, modulo the ideal (Pn), can be used to obtain a QAM signal space of 2p2n-2 points, where p is any given odd prime number. Furthermore, one subgroup of the multiplicative group of units in the quotient ring Z[ω]/(pn) can be used to obtain a QAM signal space of 6p2n-2 points; one subgroup of the multiplicative group of units in the quotient ring Z[i](pn) can be used to obtain a QAM signal space of 4p2n-2 points which is symmetrical over the quadrants of the complex plane and useful for differentially coherent detection of QAM signals; the multiplicative group of units in the quotient ring Z[ω]/(2n) can be used to obtain a QAM signal space of 3·22n-2 points, where i=√-1, ω=(-1+√-3)/2=(-1+i√3)/2, p is any given odd prime number, Z[i] and Z[ω] are, respectively, the Gaussian integer ring and the Eisenstein integer ring. These multiplicative groups can also be used to construct block codes over Gaussian integers or Eisenstein integers which are able to correct some error patterns  相似文献   
9.
The structure of the matrix of a two phase heavy alloy, 93W-4.9Ni-2.1Fe (wt%), was characterized. The matrix phase was not the expected face centred cubic Ni-Fe-W solid solution with a large grain size reported in the literature. Instead, an amorphous phase containing fine grained crystals as well as intermetallic compounds having different compositions were found. The partition of tungsten from the matrix toward the tungsten phase resulted in formation of different phases in the matrix. Under furnace cooling, the matrix phase was composed of an amorphous phase for the matrix phase remote from the tungsten grain-matrix interfaces, and a strained FeNi intermetallic phase near the interfaces. For specimens solution treated at temperatures between 1000–1400 °C followed by water quenching, an intermetallic phase rich in tungsten, (Ni, Fe) W, evolved and surrounded the tungsten grains in clusters. The relative abundance of this intermetallic phase was highest for a solution treatment temperature of 1400 °C, indicating that the formation of this phase was a result of supersaturation of tungsten in the matrix phase and retarded partition of tungsten from the matrix phase to tungsten grains under a rapid cooling condition.  相似文献   
10.
海洋丝状真菌转化石油烃的研究   总被引:8,自引:0,他引:8  
研究从湄洲湾海域分离的4株丝状真菌MF1,MF2,MF3,MF4的生长特性及去除油污的过程,观察在温度26℃,初始油浓度在3g/l,培养12d的过程中培养液的变化,分析培养液的pH值及原油的去除率与时间的关系,结果表明,丝状真菌去除原油的[过程是生物吸附与生物降解相结合的生物转化过程,比较革兰氏阴性细菌与丝状真菌细胞壁组成,结构,得出海洋微生物的脱油作用与其细胞壁有直接的关系。  相似文献   
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