关于к-集压缩正固有值的一些结果(英文)

本文首先推广Nussbaum的结果(见Lectuer Notes in Mathematics,886,303～331,Springer(1981))然后,应用此结果获得一推论,它推广了Nussbaum(见上文)Masabo and Stuart(见Nonlinear Anal.3(1979),35～44)和Krein and Rutman(见Uspehi Mat.Nauk 3,No1,(23 1948:3～95)的结果.     

Morphology,crystal structure and hydration of calcined and modified anhydrite

The effects of calcination and modification on the morphology (shapes and textures) and crystal structure of anhydrite powders were studied. The results show that, calcination at 100°C causes anhydrite to disintegrate into smaller crystals, accompanied by a slight increase in d-spacing. Without calcination and modification, the solidification time and curing time of anhydrite are 15 and 77 h, respectively. After the treatment, however, the solidification time and curing time are shortened significantly to 9.5 and 14 min, respectively. The compressive and flexural strengths of hydration products made from the treated anhydrite reach 10.2 and 2.0 MPa, respectively. The much shorter solidification and curing time make it possible to use anhydrite as a building and construction material.     

Biosorption and biodegradation of polycyclic aromatic hydrocarbons by Phanerochaete chrysosporium in aqueous solution

Biosorption and biodegradation of phenanthrene and pyrene by live and heat-killed Phanerochaete chrysosporium are investigated to elucidate the bio-dissipation mechanisms of polycyclic aromatic hydrocarbons(PAHs) in aqueous solution and its regulating factors.The effects of nutrient conditions(carbon source and nitrogen source concentrations),the co-existing Cu 2+,and repeated-batch feed of PAHs on the biosorption and biodegradation are systematically studied.The removal of PAHs by dead bodies of P.chrysosporium is attributed to biosorption only,and the respective partition coefficients of phenanthrene and pyrene are 4040 and 17500 L/kg.Both biosorption and biodegradation contribute to the dissipation of PAHs by live P.chrysosporium in water.After a 3-d incubation,the removal percentage via biosorption are 19.71% and 52.21% for phenanthrene and pyrene,respectively.With the increase of the incubation time(3 40 d),biodegradation gradually increases from 20.40% to 60.62% for phenanthrene,and from 15.55% to 49.21% for pyrene.Correspondingly,the stored-PAHs in the fungal bodies decrease.Under the carbon-rich and nitrogen-limit nutrient conditions,the removal efficiency and biodegradation of phenanthrene and pyrene are significantly promoted,i.e.99.55% and 92.77% for phenanthrene,and 99.47% and 83.97% for pyrene after a 60-d incubation.This phenomenon is ascribed to enhanced-biosorption due to the increase of fungal biomass under carbon-rich condition,and to stimulated-biodegradation under nitrogen-limit condition.For the repeated-batch feed of phenanthrene,the pollutant is continuously removed by live P.chrysosporium,and the contribution of biodegradation is enhanced with the repeated cycles.After 3 cycles,the biodegradation percentage is up to 90% with each cycle of a 6-d incubation.     

粉末冶金制备的AISI 8620钢渗碳后的磨损和力学性能

The effect of carburization on the tensile strength and wear resistance of AISI 8620 steel produced via powder metallurgy was investigated. Alloys 1 and 2 (with 0.2wt% C and 0.25wt% C, respectively) were first pressed at 700 MPa and then sintered at 1300, 1400, or 1500°C for 1 h. The ideal sintering temperature of 1400°C was determined. Afterward, Alloys 1 and 2 sintered at 1400°C were carburized at 925°C for 4 h. The microstructure characterization of alloys was performed via optical microscopy and scanning electron microscopy. The mechanical and wear behavior of carburized and noncarburized alloys were investigated via hardness, tensile, and wear tests. After carburization, the ultimate tensile strength of Alloys 1 and 2 increased to 134.4% and 138.1%, respectively. However, the elongation rate of Alloys 1 and 2 decreased to 62.6% and 64.7%, respectively. The wear depth values of Alloy 2 under noncarburized and carburized conditions and a load of 30 N were 231.2 and 100.1 μm, respectively. Oxidative wear changed to abrasive wear when the load transitioned from 15 to 30 N.     

Identification of three major Bemisia tabaci biotypes in China based on morphological and DNA polymorphisms

The sweet potato whitefly, Bemisia tabaci, is a complex species, and many of its biotypes are important agricultural pests. The B and Q biotypes are invasive and coexist with the native Cv biotype on vegetable and ornamental crops in China. In this study, these three biotypes were identified based on their morphological characteristics, RAPD–PCR analysis, and DNA sequences of the COI gene. The anterior and posterior wax fringes of the B, Q, and Cv biotypes significantly differed from each other. Based on this morphological characteristic, the three biotypes can easily be distinguished in greenhouses and fields. Genomic DNA RAPD–PCR band patterns also revealed differences between these biotypes using the H16 primer. The B biotype has three bright DNA bands between 250 and 600 bp, the Q biotype only has one bright band at 300 bp, while the Cv biotype has no band between 250 and 500 bp. Both the Cv and Q biotypes have two bright bands at 750 and 1000 bp while the B biotype has only one band at 1000 bp. Based on the COI gene, the genetic identity between B and Cv, B and Q, and Q and CV was 85.8%, 94.7%, and 86.0%, respectively. The MP tree indicated that the phylogenetic relationship between the B and Q biotypes is much closer than that between the B and Cv or the Q and Cv biotypes. The uses of the morphological, RAPD–PCR, and DNA sequencing methods in biotype identification of B. tabaci are discussed.     

Application of Spacer Fabric for Protecting Cushion

Spacer fabric is a typical three-dimensional fabric, including upper layer, lower layer, and spacer layer. It is widely applied in protecting cushion products for unique space structure, which attributes good comfortability to infants and the disabled elderly in reducing diseases resulting from hot and humidity under long-time sitting and lying period. It necessitates studying the microenvironment change between body and clothes and corresponding performance. Compressibility. air permeability, heat and moisture permeability, and bending and humiture in microenvlronment of spacer fabric are analyzed and compared with foam cushion and nonwoven cushion. Experimental results show that corresponding performance of spacer fabric is better in protecting cushion than those of foam and nonwoven. Compared with traditional foam cushion and non-woven cushion, spacer fabric is more suitable for protecting cushion, and provides an alternative and optimal cushion material in medical products to protect infants and the disabled elderly from bedsores resulted from long-time sitting and lying.     

Establishing Submersed Macrophytes via Sinking and Colonization of Shoot Fragments Clipped off Manually

In this paper, sinking and growth of apexes and mid-stems of Myriophyllum spicatum L., Hydrilla verticillata （L.f.） Royle and Ceratophyllum demersum L. in concrete ponds containing eutrophic water and sediment were investigated. Sinking rates of apexes and mid-stems reached 34.8% and 4.4% at the 6 th day and 91.1% and 66.7% at the 22 nd day for M. spicatum, 57.8% and 55.6% at the 6 th day and 100% and 97.8% at the 22 nd day for H. vertieillata, 18.9% and 86.7% at the 6 th day and 95.6% and 100% at the 22 nd day for C. demersum, respectively. Most sunken fragments established themselves successfully with significant growth. Total shoot length ofplantlets developed from apexes and mid-stems increased by 399% and 61% for M. spicatum, 593% and 256% for H. vertieillata and 114% and 104% for C. demersum, respectively. The results showed that it was feasible to establish submersed macrophytes via sinking and colonization of shoot fragments clipped off manually.     

Data acquisition, analysis and applications of multi-sensor integration

This paper presents some key techniques for multisensor integration system, which is applied to the intelligent transportation system industry and surveying and mapping industry, e.g. road surface condition detection, digital map making. The techniques are synchronization control of multisensor, spacetime benchmark for sensor data, and multisensor data fusion and mining. Firstly, synchronization control of multisensor is achieved through a synchronization control system which is composed of a time synchronization controller and some synchronization subcontrollers. The time synchronization controller can receive GPS time information from GPS satellites, relative distance information from distance measuring instrument and send spacetime information to the synchronization subcontroller. The latter can work at three types of synchronization mode, i.e. active synchronization, passive synchronization and time service synchronization. Secondly, spacetime benchmark can be established based on GPS time and global reference coordinate system, and can be obtained through position and azimuth determining system and synchronization control system. Thirdly, there are many types of data fusion and mining, e.g. GPS/Gyro/DMI data fusion, data fusion between stereophotogrammetry and PADS, data fusion between laser scanner and PADS, and data fusion between CCD camera and laser scanner. Finally, all these solutions presented in paper have been applied to two areas, i.e. landborne intelligent road detection and measurement system and 3D measurement system based on unmanned helicopter. The former has equipped some highway engineering Co., Ltd. and has been successfully put into use. The latter is an ongoing research.     

弱内向α-凝聚映象的非零不动点定理

K.Deimling and Hu shouchuan(1988),获得了弱内向映象的正不动点定理.本文主要目的是推广他们的结果.     

етаев型约束保守系的拉格朗日方程及其哈密顿方程

根据有Четаев型约束的、一般形式的拉格朗日方程,建立有Четаев型约束、保守力学系的拉格朗日方程。根据有非线性约束力学系的哈密顷方程,建立有Четаев型约束力学系的哈密顿方程。     

一类时间分数阶扩散方程中的源项反演解法

考虑了一类具有Neumann边界的时间分数阶扩散方程源项反演问题.首先,从分离变量法出发将反问题归结为第1类Volterra积分方程,从而揭示出反问题的不适定性; 其次,为了获得反问题的条件稳定性,通过分数阶数值微分将第1类Volterra积分方程转化为第2类Volterra积分方程,建立源项反问题的条件稳定性和误差估计; 最后,引进磨光正则化,获得稳定的分数阶数值导数,将其代入求解第2类积分方程,从而稳定地重建出仅依赖时间变量的源项.数值实验结果验证了所得反演算法的有效性.     

三维定常对流扩散方程的双方程方法

三维定常对流扩散方程的经典边界积分方程,其类型关于未知对流扩散势导数是第一类积分方程,关于未知对流扩散势是第二类积分方程。本文从格林公式出发,通过建立位势的单、双场守恒积分公式,推导出三维定常对流扩散方程新的边界积分方程,其类型与经典方程相反。对不同的边界采用不同的方程,由此把双方程边界元方法推广到三维空间。     

一类二阶线性微分方程的可积判据

提出了一类新二阶变系数线性微分方程，说明这类方程一般是没有初等解的．然后对这类方程引进特征方程，给出了一个实用的可积充分判据及其通解的积分表达式，从而扩大了常微分方程的封闭可解范围．     

新二阶非线性微分方程的求解定理

提出了一类新二阶非线性微分方程,对它引进特征方程的概念,给出了一个实用的可积充分判据及其通解的积分表述式,在退化情形下,导出了两类新二阶变系数线性微分方程的求解定理,所得结果扩大了常微分方程的求解范围.     

径向励磁低速同步电动机的电路模型

用电势法建立了径向励磁低速同步电动机的电路模型,包括:电势方程、参数计算式和等效电路图.提出了同步后的这种电动机可等效于一台异步电动机的观点,在此基础上得到了电磁转矩及最大转矩的表达式,为分析和研究这种电动机奠定了基础.     

稳定求解第一类Fredholm积分方程的一个方法

为了得到第一类Fredholm积分方程稳定的数值解，对p个不同的光滑因子，分别利用光滑化方法求解，可得到p组带有光滑因子的稳定解．然后利用外插值的方法，外推得到光滑因子为零时的积分方程的稳定解．通过数值算例表明，该方法是稳定求解第一类Fredholm积分方程的一个有效途径．     

抛物型复方程初边值问题解的惟一性

给出了一类抛物复方程的条件和抛物型复方程初边值问题的提法，然后用抛物复方程的极值原理证明了上述边值问题解的惟一性。     

一类非线性双曲型方程弱解的唯一性

本文在放宽的条件下研究了一类非线性双曲型方程弱解的唯一性,从而对此类方程解的唯一性问题的研究得到了补充和完善。     

一类非线性弹性梁方程解的存在性

研究了一类非线性弹性梁方程的初边值问题,考虑了材料的粘性效应及非线性外阻尼,建立了一类轴向载荷作用下的非线性弹性支承梁方程,并利用Faedo-Galerkin方法,证明了该方程在一定的初边值条件下解的存在性,为力学中弯曲与扭转联合作用下具有结构阻尼的振动问题的研究与计算提供了数学依据。