Undetected error probability of q-ary constant weight codes

In this paper, we introduce a new combinatorial invariant called q-binomial moment for q-ary constant weight codes. We derive a lower bound on the q-binomial moments and introduce a new combinatorial structure called generalized (s, t)-designs which could achieve the lower bounds. Moreover, we employ the q-binomial moments to study the undetected error probability of q-ary constant weight codes. A lower bound on the undetected error probability for q-ary constant weight codes is obtained. This lower bound extends and unifies the related results of Abdel-Ghaffar for q-ary codes and Xia-Fu-Ling for binary constant weight codes. Finally, some q-ary constant weight codes which achieve the lower bounds are found.      

Solvent‐free free‐radical frontal polymerization: A new approach to quickly synthesize poly(N‐vinylpyrrolidone)

The first synthesis of poly(N‐vinylpyrrolidone) without solvent by free‐radical frontal polymerization at ambient pressure is reported. The appropriate amounts of two reactants N‐vinyl‐2‐pyrrolidone (NVP) and initiator 2,2′‐azobis‐isobutyronitrile (AIBN) without solvent were mixed together at ambient temperature. Frontal polymerization was initiated by heating the wall of the tube with a soldering iron, and the resultant hot fronts were allowed to self‐propagate throughout the reaction vessel. Once initiated, no further energy was required for polymerization to occur. To suppress the fingers of molten monomer, a small amount of nanosilica was added. The dependence of the front velocity and front temperature on the AIBN concentration was thoroughly investigated. The as‐prepared polymers were characterized by gel permeation chromatography (GPC) and thermogravimetric analysis (TGA). Results show that without postpolymerization solvent removal, waste production can be reduced. Solvent‐free FP could be exploited as a means for preparation of PVP with the potential advantage of higher throughput than solvent‐based methods. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 2177–2185, 2008     

On the Generalizations of Hilbert＇s Inequality

In this paper, by employing a refined Cauchy＇s inequality, some strengthened Hilbert＇s inequality with parameter A, B,λ, are further improved.     

A critically loaded multirate link with trunk reservation

We consider a loss system model of interest in telecommunications. There is a single service facility with N servers and no waiting room. There are K types of customers, with type ί customers requiring A _ί servers simultaneously. Arrival processes are Poisson and service times are exponential. An arriving type ί customer is accepted only if there are Rί(⩾A_ί ) idle servers. We examine the asymptotic behavior of the above system in the regime known as critical loading where both N and the offered load are large and almost equal. We also assume that R ₁,..., R _K-1 remain bounded, while R _K ^N ←∞ and R _K ^N /√N ← 0 as N ← ∞. Our main result is that the K dimensional “queue length” process converges, under the appropriate normalization, to a particular K dimensional diffusion. We show that a related system with preemption has the same limit process. For the associated optimization problem where accepted customers pay, we show that our trunk reservation policy is asymptotically optimal when the parameters satisfy a certain relation. This revised version was published online in June 2006 with corrections to the Cover Date.     

缠结对超高分子量聚丙烯腈特性粘度测定的影响

在以粘度法测定超高分子量聚丙烯腈(Ultra-High Molecular WeightPOlyacrylonitrile,以下简称UHMWPAN)分子量时发现,在溶解完全的用于测定特性粘度的UHMWPAN二甲基甲酰胺(DMF)稀溶液中,大分子链间保留着未被溶剂舒解的“天生缠结”(Inborn Entanglement),使所测特性粘度和表观分子量偏大.天生缠结是高聚物在聚合过程产生,它在稀溶液中保留的数量受到溶解和溶液处理条件等因素影响,通过机械剪切,可在无机械降解状态下完全解除大分子链间的天生缠结,得到没有缠结影响的正确特性粘度和分子量,由此确立UHMWPAN特性粘度测定方法.     

The effect of stoichiometry on chain segment and ion mobility in partially polymerized epoxy systems

The temperature dependence of steady-shear viscosity and ionic conductivity were measured for a series of unreacted mixtures and partially cured, ungelled samples of diglycidyl ether of bisphenol-A (DGEBA) and an amine cross-linking agent, diamino diphenyl sulfone (DDS). Six stoichiometric ratios of epoxide groups to amine hydrogens were examined. Free volume expressions were used to model the temperature dependence of the conductivity and viscosity for the unreacted DGEBA-DDS mixtures. In addition, these expressions were combined to successfully correlate changes in viscosity and conductivity during the DGEBA-DDS polymerization prior to gelation. It also was demonstrated that the change in weight average molecular weight during polymerization could be interpreted from the dielectric data. Through studying variations in the stoichiometry, it was possible to examine the effects of changes in chemical structure and ion concentration on the fitted parameters in the free volume models. The inherent ion transport factor (ζ₀) was found to be inversely proportional to the concentration of ions in the test samples. The fractional free volume for segmental motion (B) was found to increase with an increase in the glass transition temperature and to be a function of the rigidity of the polymer. ©1995 John Wiley & Sons, Inc.     

浅谈课堂教学

文章分析了课堂教学的重要性，提出了提高课堂教学质量的重要环节。     

连杆机构的拆杆运动弹性动力分析方法

为简化连杆机构运动弹性动力分析的计算方法(简称KED分析),提高计算速度,使KED分析方法能在机械设计中推广应用,提出“拆杆KED 分析方法”.它是根据连杆机构中各构件之间动力耦合关系,把整个机构KED分析近似等效为机构中几个单一构件的KED分析,从而较大程度地提高了连杆机构KED分析的效率.为KED分析的应用和推广提供了一条新途径.     

拟大经济现货-金融市场及均衡存在性

建立了加权的不完全金融市场模型，证明了此模型均衡的存在性。     

齐型空间上算子的加权内插及其应用

本文在齐型空间上建立了算子的加权情形下的实内插定理，运用该结果，立即可推导出齐型空间上Ｃａｌｄｅｒｏｎ－Ｚｙｇｍｕｎｄ算子的加权Ｌ^ｐ有界性（ｐ＞１）和弱Ｌ¹有界性。