Error-detecting abilities of binary nonlinear constant weight codes

CONSTANT weight codes are very important in coding theory for its application to communication. In refs. [1—5], the undetected error probabilities (UEP)of binary nonlinear constant weight codes (BNCW) were studied, and Wang et al. showed that when n】8, BNCW codes (n, 2, ω) were not proper, Wang proposed a conjecture that when n】4δ and δ】 1, BNCW codes (n, 2δ, ω) are not proper. in this note, the error-detecting abilities

A new mixed scheme based on variation of constants for Sobolev equation with nonlinear convection term

A new mixed scheme which combines the variation of constants and the H1-Galerkin mixed finite element method is constructed for nonlinear Sobolev equation with nonlinear con- vection term. Optimal error estimates are derived for both semidiscrete and fully discrete schemes. Finally, some numerical results are given to confirm the theoretical analysis of the proposed method.

Nonlinear parametric interactions in ion-implanted semiconductor plasmas having strain-dependent dielectric constants

We report nonlinear parametric interactions using a hydrodynamic model of ion-implanted semiconductor plasmas having strain-dependent dielectric constants（SDDC）. High-dielectric-constant materials are technologically important because of their nonlinear properties. We find that the third-order susceptibility varies in the range 10^-14--10^-12m^2·V^-2 for ion-implanted semiconductor plasmas, which is in good agreement with previous results. It is found that the presence of SDDC in ion-implanted semiconductor plasma modifies the characteristic properties of the material.

Third-order elastic, piezoelectric, and dielectric constants

The definitions of the third-order elastic,piezoelectric,and dielectric constants and the properties of the associated tensors are discussed.Based on the energy conservation and coordinate transformation,the relations among the third-order constants are obtained.Furthermore,the relations among the third-order elastic,piezoelectric,and dielectric constants of the seven crystal systems and isotropic materials are listed in detail.These third-order constants relations play an important role in solving nonlinear problems of elastic and piezoelectric materials.It is further found that all third-order piezoelectric constants are 0 for 15 kinds of point groups,while all third-order dielectric constants are 0 for 16 kinds of point groups as well as isotropic material.The reason is that some of the point groups are centrally symmetric,and the other point groups are high symmetry.These results provide the foundation to measure these constants,to choose material,and to research nonlinear problems.Moreover,these results are helpful not only for the study of nonlinear elastic and piezoelectric problems,but also for the research on flexoelectric effects and size effects.

Improvement of sintering,nonlinear electrical,and dielectric properties of ZnO-based varistors doped with TiO2

The effects of TiO2 on sintering and nonlinear electrical properties of（98.5-x）ZnO–0.5MnO2–0.5Co2O3-0.5Bi2O3–xTiO2（x = 0.3,0.5,0.7,0.9 mol%） ceramic varistors prepared by the ceramic technique are investigated in this work.The optimum sintering temperature of the prepared samples is deduced by determining the firing shrinkage and water absorption percentages.The optimum sintering temperature is found to be 1200℃,at which each of the samples shows a maximum firing shrinkage and minimum water absorption.Also minimum water absorption appears in a sample of x = 0.9 mol%.Higher sintering temperature and longer sintering time give rise to a reduction in bulk density due to the increased amount of porosity between the large grains of ZnO resulting from the rapid grain growth induced by the liquid phase sintering.The crystal size of ZnO decreases with increasing TiO2 doping.The addition of TiO2 improves the nonlinear coefficient and attains its maximum value at x = 0.7 mol% of TiO2,further addition negatively affects it.A decrease in capacitance consequently in the dielectric constant is recorded with increasing the frequency in a range of 30 kHz–200 kHz.The temperature and composition dependences of the dielectric constant and AC conductivity are also studied.The increase of temperature raises the dielectric constant because it increases ionic response to the field at any particular frequency.

Extraction of optical constants and thickness of nanometre scale TiO2 film

TiO2 thin films were deposited on glass substrates by sputtering in a conventional rf magnetron sputtering system. X-ray diffraction pattern and transmission spectrum were measured. The curves of refraction index and extinction coefficient distributions as well as the thickness of films calculated from transmission spectrum were obtained. The optimization problem was also solved using a method based on a constrained nonlinear programming algorithm.

LINEAR AND NONLINEAR DIELECTRIC PROPERTIES OF PARTICULATE COMPOSITES AT FINITE CONCENTRATION

An analytical method was proposed dielectric properties for particulate composites. to calculate effective linear and nonlinear The method is based on an approximate solution of two-particle interaction problem, and it can be applied to relatively high volume concentration of particles （up to 50%）. Nonlinear dielectric property was also examined by means of secant method. It is found that for low applied electric filed the proposed method is close to Stroud and Hui＇s method and for high applied electric filed it is close to Yu＇s method.

非线性曲面梁形态优化及恒压支撑装置设计

基于超前支护设备顶梁支撑结构研究一种恒压支撑装置的设计方法,恒压支撑装置由正刚度线性弹簧、负刚度非线性平面曲梁及承压气囊组合而成。通过对巷道顶板应力场分析,得到支撑结构的边界条件;利用B样条曲线简述负刚度非线性平面曲梁的特点;基于遗传算法与非线性有限元法对负刚度非线性平面曲梁进行形态优化设计;依据恒压支撑装置的工作原理,对线性螺旋弹簧刚度/强度特性进行分析与设计;对恒压支撑装置的零部组件进行设计,实现支撑装置输出压强大小恒定及自我保护功能。恒压支撑装置设计方法为综掘巷道超前支护研制提供了有力技术支撑。

NONLINEAR ELASTICITY OF BLOOD ARTERIAL DUCT

The paper deals with nonlinear elasticity of blood arterial duct, in which the artery is modeled to bea locally triclinic, transverse isotropic, incorapressible, axisymmetric and thickwalled tube with large deformations, The nonlinear coustitutive relationship of arterial tissues is based on the theorv of Green and Adkins. A nonlinear strain energy density function is introduced for nonlinear stress-strain relationship of second order, in which the coefficient of each term is expressed by means of a Lame’s constant, The elasticity constants are nqcessary to describe such a uonlinear finite strain etastieity of the second order, These constants are determined by means of the stress-strain increment theory.

非线性Thau观测下的水下机器人定速推进故障识别

水下机器人在水中运动时受水流、湍流和涡流等流体动力学的复杂影响,会对推进系统产生非线性影响,使得工作状态发生微小变化,难以准确估计其运行状态,增加了故障识别的难度。为此,提出一种非线性Thau观测下的水下机器人定速推进故障识别方法。利用无损卡尔曼滤波估计水下机器人定速推进器的状态量;通过非线性Thau观测算法,结合状态量估计结果建立非线性Thau观测器,识别定速推进故障;通过模糊神经网络逼近非线性Thau观测器内的有界非线性不确定性扰动,提升故障识别精度。实验结果证明:该方法可有效估计水下机器人定速推进器的状态量,并逼近非线性Thau观测器的有界非线性不确定性扰动;而且可有效识别定速推进故障,故障识别精度较高。

轨道车辆用沙漏橡胶弹簧设计及其非线性等频特性分析

为了解决转向架空间有限与横向大变形间的结构性矛盾,提出了一种表征沙漏橡胶弹簧等频承载特性的计算方法,并以一款高铁列车转向架的沙漏橡胶弹簧为研究对象,采用1P4E网格法解决沙漏橡胶弹簧大变形仿真时因网格扭曲导致的收敛性难题;通过尺度敏感性分析计算出影响沙漏橡胶弹簧非线性刚度的四大结构尺寸;通过搭建等频承载模型,获得沙漏橡胶弹簧满足等频特性的承载区域,该沙漏橡胶弹簧满足等频承载要求的承载位移区为41~57.4 mm。

自适应材料插值在柔顺常力机构非线性拓扑优化中的应用

为解决柔顺常力机构的非线性拓扑优化中存在的数值不稳定问题,对非线性拓扑优化的材料插值方法进行了研究。首先,根据常力机构的工作特点以及输出特性,分别构建了其非线性拓扑优化的设计域以及优化模型;然后,对数值不稳定问题产生的原因展开了讨论,从控制应变以避免数值不稳定问题的角度出发,提出了一种新的材料插值模型,模型中引入了参数α,对低密度单元抗变形能力进行了统一调节,并根据最大等效应变给出了一种参数α的自适应调整策略;最后,基于提出的材料插值模型,推导了常力机构优化模型的目标函数敏度表达式,对不同常力区间的常力机构进行了优化,分别对优化结果以及优化效率进行了讨论;并搭建了实验平台,对优化得到的常力机构的实际输出性能进行了验证。实验结果显示:该方法优化得到的常力机构在特定的常力区间内,最大输出力误差为2.3%。研究结果表明:自适应材料插值方法有效地避免了数值不稳定问题,稳定性得到了提升,且优化效率相比于附加超弹材料方法得到了提升。

光伏阵列输出变化下光伏并网点恒定潮流控制方法

随着可再生能源的大规模并网,光伏系统需要考虑更多控制目标,为此,提出了一种新型光伏并网点恒定潮流控制方法。首先,以分布式输出补偿原理为核心,构建分布式潮流控制结构;其次,利用相似日理论和BP神经网络预测出光伏阵列输出情况,推导出潮流恒定值;然后,以其误差累积量最小、总网损最小为目标,设置目标函数;最后,采用结合非线性递增策略的非线性扩散粒子群算法求解,获取最佳控制参数。结果显示,该控制方法实施70 h后,光伏并网运行网损均值为2.2 kW/h,证明了该方法的实用性。

一种光伏电池最大功率跟踪算法

光伏电池的输出特性呈现非线性,为了确保光伏阵列的输出功率始终在最大功率点上,需要采用适当的控制算法来实现最大功率跟踪。采用固定电压法与变步长电导增量法相结合的方法来实现最大功率跟踪。该方法解决了固定电压法在外界环境剧烈变化时不能工作在最大功率点上,以及电导增量法的动态跟踪速度和稳态输出稳定性不能协调的问题。理论分析证明了该算法的有效性及实用性。

基于Smith预估补偿与RBF神经网络的改进PID控制

由于工业界普遍存在且难以很好地解决恒温控制的大滞后和非线性问题,特提出了将Smith预估补偿和RBF神经网络与PID控制相结合的改进PID控制算法。该算法利用Smith预估补偿对温度滞后问题进行处理,利用RBF网络在线学习能力进行PID参数的动态调整处理非线性问题,进而保证恒温控制使系统处于最佳状态。

掺杂TiO_2对ZnO压敏电阻器的性能影响

提出一种低压ＺｎＯ压敏电阻器的制造方法。研究了它的微观结构和导电机理。在五元配方的基础上加入ＴｉＯ２，并用适当的工艺可制得性能优良的低压产品。

最佳非线性等重检错码的存在性问题

本文分析了二进制（２ｍ，２，ｍ）非线性等重码的不可检错误概率，证明了当ｍ≥５时，它不是最佳检错码，从而完全证明了作者提出的：当ｎ≥９时，不存在最佳二进制非线性等重码的猜想．

TiO_2低压压敏陶瓷材料研究

通过对ＴｉＯ２低压压敏陶瓷材料工艺和配方的研究，找出了这种材料的最佳烧结温度，并通过掺杂少量的ＭｎＯ２添加剂，非线性系数有显著地提高。还研究了这种压敏陶瓷材料表观介电常数的频率特性，以及非线性系数的温度稳定性等。

(Sr^(2+),Bi^(3+),Si^(4+),Ta^(5+))掺杂的TiO_2压敏陶瓷中Ta^(5+)的研究

研究Ta2 O5对 (Sr,Bi,Si,Ta)掺杂的TiO2 基压敏陶瓷压敏特性及电容特性的影响 ,发现按配方TiO2+0 .3%(SrCO3+Bi2 O3+SiO2 ) +0 .1 %Ta2 O5配制的样品具有最低压敏电压 (E1 0mA =1 .2V·mm- 1 )、最大相对介电常数 (εra=2 .0 0 2× 1 0 5)及较小非线性系数 (α =2 .6 )。考虑到材料的低压敏电压和大介电常数的要求 ,Ta2 O5最佳掺杂量在 0 .0 85mol%与 0 .1mol%之间。

金属-绝缘体复合材料介电增强的研究

研究了金属与绝缘体复合材料介电增强规律，对有效集结模型进行了修正．在相对真空的前提下，研究了金属与绝缘体复合材料介电常数随着掺入体积比的变化规律，其修正的公式也表现了与Ｄｏｙｌｅ－Ｊａｃｏｂｓ公式同样的非线性，并与Ａｇ／ＬＤＰＥ复合材料实验数据以及其它几个实验数据进行了比较。