排序方式: 共有17条查询结果,搜索用时 0 毫秒
1.
介绍了光器件在粗波分复用系统中的应用,并与密集波分复用器件进行了比较,论述了这些器件在城域粗波分复用系统中的应用优势,指出该器件的进一步研发方向。 相似文献
2.
应用原子团簇理论计算了He3体系的短程多体排斥作用,结果与SCF-LCAO-MO方法计算结果非常符合. 相似文献
3.
以混凝土抗氯离子渗透为主要研究目的,应用致密堆积理论拌制混凝土试件并与基准混凝土为对比参照,采用压汞法测试不同水胶比和水泥浆富余系数的致密堆积混凝土的孔结构,依据ASTM C1202—97标准测试致密堆积混凝土的电通量,同时对基准混凝土的孔结构和电通量进行测试并比较,研究孔结构对电通量的影响。结果表明:电通量受多种因素的共同影响,其中致密堆积结构、致密堆积混凝土的最可几孔径、通孔孔隙率及孔径分形维数对氯离子扩散有较显著的影响。 相似文献
4.
Summary This paper addresses the problem of portfolio selection in finance. In many cases, currently available software to compute
the efficient frontier runs into difficulty in problems with more than about 600 securities. To proceed beyond this size,
it is often necessary to modify the problem in which case there is typically a loss of information. In this paper, we discuss
a computer capability that can exactly compute mean-variance efficient frontiers of problems with up to 2,000 securities in
very reasonable time (even if a problem’s covariance matrix is 100% dense).
The paper also discusses an augmentation to the theory of portfolio selection that allows multiple objectives (such as dividends,
liquidity, social responsibility, amount invested in R&D, and so forth) to be incorporated into the portfolio selection process.
In such problems, the efficient set is no longer a “frontier,” but is now best described as a “surface” with the interesting
property that it is composed of platelets (like on the back of a turtle). Moreover, the computer capability that can compute
the exact efficient frontier of a mean-variance problem with up to 2,000 securities also has, after additional coding, the
ability to compute exactly all platelets of the efficient surface of a tri-criterion portfolio problem with up to 400 securities.
Zusammenfassung In dieser Arbeit stellen wir einen leistungsf?higen Rechenalgorithmus vor, um den effizienten Rand (die nichtdominierten Alternativen) von Portfolio-Auswahlproblemen in der Finanzierung zu bestimmen. Wir bezeichnen den Berechnungsalgorithmus, der in Java programmiert ist, mit MPQ (multi-parametric quadratic programming). MPQ weist gegenüber bisherigen Berechnungsverfahren eine Reihe von Vorteilen auf: Es kann für umfangreiche Anwendungsf?lle genutzt werden, ist durch passable Rechenzeiten charakterisiert und kann die Menge effizienter Alternativen in einem Bruchteil bisher üblicher Rechenzeiten bestimmen.相似文献
5.
在总结国内外研究的基础上,提出骨架密实型水泥稳定碎石,用以减少基层收缩裂缝产生,从而提高水泥稳定碎石基层使用性能,同时与国内规范推荐级配的水泥稳定碎石作比较,结果表明,骨架密实型水泥稳定碎石具有优良的路用性能。 相似文献
6.
陈友义 《汕头大学学报(人文社会科学版)》2002,18(4):93-99
潮汕是一个具有独特而优越地理环境的地域。独特而优越的地理环境赋予了潮汕人精细的社会生产 ,造就了潮汕人精明的文化心态 ,从而使潮汕传统文化形成鲜明的精细特色。 相似文献
7.
赵林 《佛山科学技术学院学报(社会科学版)》1994,(4)
以直线上概率测度卷积半群的有关性质为基础,证明了半直线R+上的概率测度卷积半群(,*)的弱素元全体在(.*)中稠密及I0元全体在(,*)的无穷可分元全体中稠密.这些结果对广义卷积代数(,*)的半群结构的研究具有重要意义. 相似文献
8.
Flexible Class of Skew-Symmetric Distributions 总被引:2,自引:0,他引:2
Abstract. We propose a flexible class of skew-symmetric distributions for which the probability density function has the form of a product of a symmetric density and a skewing function. By constructing an enumerable dense subset of skewing functions on a compact set, we are able to consider a family of distributions, which can capture skewness, heavy tails and multimodality systematically. We present three illustrative examples for the fibreglass data, the simulated data from a mixture of two normal distributions and the Swiss bills data. 相似文献
9.
We provide the first interesting explicit lower bounds on efficient approximability for two closely related optimization problems
in graphs, MINIMUM EDGE DOMINATING SET and MINIMUM MAXIMAL MATCHING. We show that it is NP-hard to approximate the solution of both problems to within any constant factor smaller than
. The result extends with negligible loss to bounded degree graphs and to everywhere dense graphs.
An extended abstract of this paper was accepted at the 14th Annual International Symposium on Algorithms and Computation,
ISAAC 2003. 相似文献
10.
提出了匀速运动粒子的运动是不均匀的、实际上粒子在作脉动、其脉动速度是周期性变化的观点,给出了粒子的动能与脉动周期的关系,并用初等数学推出了谐振子和别的一系列束缚态的能级公式. 相似文献