Optimal solutions for a dynamic bandwidth allocation scheme in high-speed networks

In this paper, we investigate the problem of determining the optimal bandwidth allocation for a Dynamic Bandwidth Allocation Scheme (DBAS). The objective is to minimize the total amount of bandwidth required to satisfy the Quality of Service (QoS) requirements of all traffic streams. It is shown that when the performance functions satisfy a certain number of conditions, there exists a unique optimal bandwidth allocation such that, for each traffic stream, either its QoS is just satisfied or its QoS is over-satisfied and it is allocated zero bandwidth. Such an allocation is said to be efficient. It is also shown that there exists a unique efficient allocation in the entire feasible region. An iterative algorithm is developed to compute the efficient allocation employing its special properties. Numerical examples are presented to demonstrate how the algorithm works. Future extensions of this work are also discussed.Partially supported by NSERC of Canada through grants OGP14020 and STRIN-200.     

大学男子健美训练与体质提高的探究

通过２０３名大学男生的课余健美训练，测量训练前后体质各项指标，统计分析后发现，健美训练可使肺活量、体重、胸围以及引体向上的次数等明显增加．     

聚四氢呋喃及其下游产品的开发应用

本文论述了聚四氢呋喃技术进展、氨纶弹性纤维发展现状和国内外聚四氢呋喃产能和需求。     

碳纳米管的制备及研究

介绍了在直流电弧放电法制备富勒烯过程中，从阴电极表面收集到大量的碳纳米管及巴基葱，产生率达到５０％，并用电子显微镜对其进行了观察和初步研究。     

榆树林油田砂岩储层敏感性研究

榆树林油田储层粘土矿物含量较高，各种注入条件和施工条件都会对该储层造成相应的伤害，应采取相应的防护措施，为防止速敏的发生，储层的注水速度应控制在临界流速（1.0mL/min）以下，在油井转注时，可先注入1.09PV的含粘土稳定剂的进行处理，以提高产量或注入量，注入阴离子表面活性剂配置的活性水再注入地层水，不能增加地层水的渗透率，该项试验研究对指导榆树林油田的开发具有重要的意义。     

Lightpath (wavelength) routing in large WDM networks

We address the problem of efficient circuit switching in wide area optical networks. The solution provided is based on finding optimal routes for lightpaths and the new concept of semilightpaths. A lightpath is a fully optical transmission path, while a semilightpath is a transmission path constructed by chaining together several lightpaths, using wavelength conversion at their junctions. A fast and practical algorithm is presented to optimally route lightpaths and semilightpaths taking into account both the cost of using the wavelengths on links and the cost of wavelength conversion. We prove that the running time of the algorithm is the best possible in the wide class of algorithms allowing linear algebraic operations on weights. This class encompasses all known related practical methods. Additionally, our method works for any physical realization of wavelength conversion, independently whether it is done via optoelectronic conversion or in a fully optical way     

一种非调制式热释电红外传感器

基于红外技术理论提出了利用热释电红外传感器(PIS)对目标扫描过程中产生双向热电电流构成非调制式热释电红外传感器的方法,并讨论了利用双并联技术的非调制式热释电传感器。     

Emergy account for biomass resource exploitation by agriculture in China

On the basis of Odum's ecological economic measure of emergy as embodied solar energy, a system account of biomass resource exploitation by agriculture in China 2004 is developed in this paper, which supplements a former study on corresponding long-term historical trends during 1978 to 2000 (Chen et al., 2006. Emergy-based analysis of the Chinese agriculture. Agriculture, Ecosystems and Environment 115, 161–173). The aggregate fluxes and indicators for biomass resource exploitation in China 2004 are calculated and illustrated when compared with those for 2000 to elucidate the latest status of the Chinese agriculture as the exploitation sector for biomass resource. Data sources and algorithm are presented in detail as basic references for related analysis involving the ecological economy of biomass exploitation in agriculture.     

Electrical properties and positron annihilation study of (Ba<Subscript>1−<Emphasis Type="Italic">x</Emphasis></Subscript>Ho<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>)TiO<Subscript>3</Subscript> ceramics

DC resistivity, dielectric constant, dielectric loss and positron annihilation spectra of (Ba_1−x Ho _x )TiO₃ ceramics have been measured as a function of holmium concentration x. It has been found that the DC resistivity of (Ba_1−x Ho _x )TiO₃ is strongly dependent on the Ho content: it decreases three orders of magnitude and reaches a minimum at x = 0.4%. Doping with 0.6% holmium increases the permittivity of BaTiO₃ by approximately three times (from ∼1,300 to ∼4,000), with only a slight increase in the corresponding dielectric loss. The local electron density and defect concentration estimated using positron annihilation technique conforms well to the features found in the dielectric and resistivity measurements. The results have been discussed in terms of a mixed compensation model.     

房屋建筑结构无损检测方法的分析与展望

通过对现有的结构无损检测方法的总结和分析,讨论了各种方法的优缺点.并结合现场测试的要求,展望结构检测技术的发展方向与趋势.