方差分量谱分解估计的几个性质

对于线性混合模型中方差分量的估计，虽有多种方法，但一般情况下只有方差分析估计和谱分解估计有显式解，本文就线性混合模型中含两个方差分量的情形，对方差分析估计和谱分解估计进行了比较，证明了在一些条件下两个估计的方差相等，由此推出谱分解估计也具有方差分析估计的某些优良性．文末用实例进一步说明了文中的结果．     

Comparative Studies on the Mechanical Properties of a Thermoset Polymer in Tension and Compression

Results of an experimental investigation into the mechanical properties of a polyester resin in tension and compression are reported. Features of the stress-strain curves obtained are discussed. Data on the elastic modulus, Poisson ratio, and volume strains are obtained. The results of creep behavior of the material in tension and compression are also presented. It is found that the time-dependent creep obeys a power law, but the nonlinear stress dependence can be described by using the hyperbolic sine function. The effect of load type (tension or compression) on the nonlinearity of the creep is analyzed. __________ Translated from Mekhanika Kompozitnykh Materialov, Vol. 41, No. 5, pp. 633–650, September–October, 2005.     

Deformational Properties of Irradiated Composite Materials Based on PET and PE

Considering the wide applicability of polymeric composite materials, heterogeneous blends of poly(ethylene terephtalate) (PET) and polyethylenes of high and low densities (HDPE and LDPE, respectively) were investigated. Rheological (the flow-behavior index), mechanical (the yield strength and the Charpy impact strength), and morphological (crystallinity and the melting temperature) properties were detected for individual blend components and different blend compositions. A radiation treatment (-rays) was applied to improve certain characteristics of the heterogeneous blends. The results of this investigation show that the radiation modification can be successfully used to improve some physical properties of the PET-based blends and to choose individual blend components, optimum irradiation conditions, and desirable blend compositions, which allows producing materials with a predictable set of mechanical properties.     

基于主成分分析的伊犁州直县(市)综合实力评价研究

主成分分析就是利用降维的思想,在损失很少信息的前提下把多个指标转化为几个综合指标的多元统计方法.通过对伊犁州直属10个县市的18项指标基于主成分分析进行了定量分析,得到了10个县市的综合实力排名,并指出了各县市经济发展不平衡的原因,给出了相应参考政策.     

双圆盘上内序列基子模的一些性质

研究了双圆盘上的内序列基子模,该子模与经典的单变量算子理论有着深刻的联系.完整地刻画了压缩算子Sz的紧性和正规性,同时回答了Yang于2002年提出的一个问题.还给出了赋值算子L(0)限制在内序列基商模上是紧算子的一个充要条件.     

随机波动率模型下技术分析指标的一些性质(英文)

一些流行的技术指标(例如布林带,RSI,ROC等)被股市交易者广为使用.交易者将每日(小时,周,……)的实际股价作为计算某个技术指标的样本,通过观察相关频率来指导投资.技术指标的有效性已在广泛的应用中得到了验证.我们已经证明在Black-Scholes模型下,某些技术指标有许多有用的统计性质.作为更一般的情况,随机波动率模型在金融数学中得到了广泛的讨论.本文基于随机波动率模型对技术指标的统计性质进行了研究.研究结果表明,如果股票价格服从随机波动率模型,则技术指标的合理性可以得到有力的证明,从这个角度我们为技术分析奠定理论基础.     

A Study of the Relation between the Mechanical Properties and the Adhesion Level in a Laminated Packaging Material

The mechanical properties of a laminate consisting of aluminum-foil, adhesive, and polymer layers were studied in relation to the adhesion level. A special application for liquid-food packaging materials was considered. In experiments, laminates with and without adhesive layers were tested. Tensile tests were first run for every layer of the laminate, and the data obtained were then used in analyzing the results of tensile tests on the entire laminate, as well as in theoretical and finite-element calculations. Relations between different mechanical properties (such as Young's modulus, the peak stress, and the strain at the peak stress) and the adhesion level were analyzed. It was found that the tensile strength and the strain at the peak stress increased with adhesion level. Only slight differences in Young's modulus were observed at different adhesion levels.     

Effect of Radiation Modification of Disperse Polyethylene on Component Interaction and Properties of GFRP Based on It

The basic aspects of interfacial interaction between the polymer binder and the filler in glass-fiber-reinforced plastics (GFRP) based on a high-density polyethylene (HDPE) are considered. The plastics were produced by the film-powder technology using a disperse radiation-modified HDPE as the binder. It is shown that the use of the -treated HDPE powder extends the capabilities of controlling the strength properties of GFRP sheets.     

Relationship between the Contact Time of Polymer Surfaces and Their Bond Strength

Films of amorphous polystyrene (PS) (mono- and polydisperse polymers) and poly(phenylene oxide) (PPO) were brought into contact at a low pressure (0.8 MPa) under temperatures T _h from 62 to 156°C. The contact time t was varied from 2 min to 96 h. Partially healed PS-PS, PPO-PPO, and PS-PPO contacts were broken at room temperature and the shear strength in the contact zone was measured. The experimental -t curves were analyzed in double logarithmic coordinates. The value of for the three interfaces investigated was within 0.07-0.32 at T _h < T _g, where is the glass transition temperature. In the same way, the data on strength development taken from the literature for a number of polymer-polymer contacts formed both above and below T _g were analyzed, and the range of variations in proved to be roughly the same (0.05-0.35). The results obtained are discussed within the framework of theories of molecular dynamics for the polymer bulk and the interface.     

关于Baer PP和PS环的一些性质(英)

在此文中,我们对Strong-Armendariz环和Baer PP及PS环Ore-扩张R[x,x~(-1)；α]的一些性质进行了讨论研究,并得到了一些结果．主要证明了R是Baer(PP)环当且仅当R[[x]]是Baer(PP)环及R是α-rigid环时,R是Baer(PP,PS)环当且仅当R[[x]]是Baer(PP,PS)环．     

正则不可数基数反映GO-空间的性质

本文对“每一个GO-空间都是可数仿紧的”这一性质进行了推广,得到了“每一个GO-空间都是1:x∈［LX-X］}仿紧的”；论证了在一定条件下，一个拓扑空间和一个GO-空间乘积的正规性与这个拓扑空间和一个正则不可数基数的乘积正规性是等价的;并在这两个结论的基础上，又得出了一些重要的定理.     

模糊子群直积的若干性质

在Ray的论文[Onproduct of fuzzy subgroups105（1999）181—183]中，作者给出了模糊子群直积在min下的一些性质。在本文中我们将给出更多关于模糊子群直积的性质，并推广到模糊子环上；最后讨论了模糊子群的直积在t-模下的一些性质。     

关于反中心对称矩阵的某些性质探讨

利用反中心对称矩阵的定义以及翻转矩阵等技巧,给出了反中心对称矩阵的伴随矩阵、特征值及特征向量的一些新结论.     

因子分析中特征向量和主成分的应用研究

讨论了因子分析的基本思想,结合实例从相关系数矩阵出发,计算其特征根和对应的特征向量,然后给出进行主成分分析的三种方法;进行旋转前后因子载荷矩阵的共同度、累计方差、特征根等多角度比较,深刻揭示因子分析和主成分分析之间的关系.     

Influence of Filler on the Structure,Thermal Stability,and Mechanical Properties of Compositions Based on a Modified Polypropylene

Mechanics of Composite Materials - The effect of a filler on the structure, thermal stability, strength, elongation, and impact strength before and after freezing in compositions based on...     

Environmental Effects on the Mechanical Properties of Glass-FRP and Aramid-FRP Rebars

In the paper, the experimental results on the effect of temperature and moisture on the mechanical properties of FRP (Fiber-Reinforced Polymer) reinforcements are presented. FRP rebars made from glass and aramid fibers were subjected to cyclic thermal actions at temperatures ranging between 20 and 70°C, typical of natural hot-climate environments. Tensile tests were also carried out on FRP rebars. The effect of moisture was investigated by cyclic wetting and drying the FRP rebars under laboratory conditions before their testing in tension. Finally, the elastic modulus and tensile strength of the FRP rebars exposed to these cyclic actions were compared with those obtained for unexposed ones, in order to evaluate the mechanical damage caused by environmental conditions.     

Cross-Linked Thermoplastic Blends of Polyethylene with an Elastomer 2. Some Structural Characteristics and Their Relationship with Mechanical Properties

Results of an experimental investigation into the changes of some structural characteristics of binary blends of high-density polyethylene and low-density polyethylene with an elastomer (ethylene-propylene-dicyclopentadiene terpolymer, EPDM) in the course of γ-radiation and chemical cross-linking are reported for a wide range of component ratios. The data on changes in the crystallinity, density of the blends, content of the cross-linked part, as well the correlation of these characteristics with some mechanical properties, are discussed. Suggestions are put forward about the possibility of formation of a combined amorphous PE-EPDM phase with a higher structural arrangement than that in the individual components.__________Translated from Mekhanika Kompozitnykh Materialov, Vol. 41, No. 4, pp. 545–562, July–August, 2005.