Constitutive relation of an orthorhombic polycrystal with the shape coefficients

An orthorhombic polycrystal is an orthorhombic aggregate of tiny crystallites. In this paper, we study the effect of the crystalline mean shape on the constitutive relation of the orthorhombic polycrystal. The crystalline mean shape and the crystalline orientation arrangement are described by the crystalline shape function （CSF） and the orientation distribution function （ODF）, respectively. The CSF and the ODF are expanded as an infinite series in terms of the Wigner D-functions. The expanded coefficients of the CSF and the ODF are called the shape coefficients s^lm0 and the texture coefficients c^lmn respectively. Assuming that Ceff in the constitutive relation depends on the shape coefficients s^lm0 and the texture coefficients c^lmn by the principle of material frame-indifference we derive an analytical expression for C^eff up to terms linear in s^lmo and c^lmn and the expression would be applicable to the polycrystal whose texture is weak and whose crystalline mean shape has weak anisotropy. C^cff contains six unspecified material constants （λ, μ, c, s1, s2, s3）, five shape coefficients （s^2 00, s^2 20, s^4 00, s^4 20, s^4 40）, and three texture coefficients （c^4 99,c^4 20, c^4 40）, The results based on the perturbation approach are used to determine the five material constants approximately. We also find that the shape coefficients 2 and a s^2mo and s^4m0 are all zero if the crystalline mean shape is a cuboid. Some examples are given to compare our computational results.

Damage Identification in Beam-Type Structures Using Pseudo Strain Energy Density and Grey Relation Coefficient

Based on pseudo strain energy density (PSED) and grey relation coefficient (GRC), an index is proposed to locate the damage of beam-type structures in time-domain. The genetic algorithm (GA) is utilized to identify the structural damage severity of confirmed damaged locations. Furthermore, a systematic damage identification program based on GA is developed on MATLAB platform. ANSYS is employed to conduct the finite element analysis of complicated civil engineering structures, which is embedded with interface technique. The two-step damage identification is verified by a finite element model of Xinxingtang Highway Bridge and a laboratory beam model based on polyvinylidens fluoride (PVDF). The bridge model was constructed with 57 girder segments, and simulated with 58 measurement points. The damaged segments were located accurately by GRC index regardless of damage extents and noise levels. With stiffness reduction factors of detected segments as variables, the GA program evolved for 150 generations in 6 h and identified the damage extent with the maximum errors of 1% and 3% corresponding to the noise to signal ratios of 0 and 5%, respectively. In contrast, the common GA-based method without using GRC index evolved for 600 generations in 24 h, but failed to obtain satisfactory results. In the laboratory test, PVDF patches were used as dynamic strain sensors, and the damage locations were identified due to the fact that GRC indexes of points near damaged elements were smaller than 0.6 while those of others were larger than 0.6. The GA-based damage quantification was also consistent with the value of crack depth in the beam model.

Program evaluation and its application to equipment based on super-efficiency DEA and gray relation projection method

For the gray attributes of the equipment program and its difficulty to carry out the quantitative assessment of the equipment program information, the gray relation projection method is simply reviewed. Combining the super-data envelopment analysis（DEA） model and the gray system theory, a new super-DEA for measuring the weight is proposed, and a gray relation projection model is established to rank the equipment programs. Finally, this approach is used to evaluate the equipment program. The results are verified valid and can provide a new way for evaluating the equipment program.

Thermal Conductivity and Heat Transfer Coefficient of Concrete

A very simple model for predicting thermal conductivity based on its definiensis was presented. The thermal conductivity obtained using the model provided a good coincidence to the investigations performed by other authors. The heat transfer coefficient was determined by inverse analysis using the temperature measurements. From experimental results, it is noted that heat transfer coefficient increases with the increase of wind velocity and relative humidity, a prediction equation on heat transfer coefficient about wind velocity and relative humidity is given.

EFFECTIVE DIFFUSION AND EFFECTIVE DRAG COEFFICIENT OF A BROWNIAN PARTICLE IN A PERIODIC POTENTIAL

We study the stochastic motion of a Brownian particle driven by a constant force over a static periodic potential. We show that both the effective diffusion and the effective drag coefficient are mathematically well-defined and we derive analytic expressions for these two quantities. We then investigate the asymptotic behaviors of the effective diffusion and the effective drag coefficient, respectively, for small driving force and for large driving force. In the case of small driving force, the effective diffusion is reduced from its Brownian value by a factor that increases exponentially with the amplitude of the potential. The effective drag coefficient is increased by approximately the same factor. As a result, the Einstein relation between the diffusion coefficient and the drag coefficient is approximately valid when the driving force is small. For moderately large driving force, both the effective diffusion and the effective drag coefficient are increased from their Brownian values, and the Einstein relation breaks down. In the limit of very large driving force, both the effective diffusion and the effective drag coefficient converge to their Brownian values and the Einstein relation is once again valid.

Study on Entropy Weight Coefficient Method and Application for Water Quality Evaluation

In order to evaluate the quality of water environment, the conception of entropy is applied in information science, and the entropy weight model is built to evaluate comprehensively water quality. The indexes weights of water quality are determined by value of entropy. This kind of method is applied on evaluating water quality in the new water to be built. The result shows that the water quality in it which supply water is between grade Ⅲ and Ⅳ, and the result is similar to that of gray related method.

Minimum wall pressure coefficient of orifice plate energy dissipater

Orifice plate energy dissipaters have been successfully used in large-scale hydropower projects due to their simple structure, convenient construction procedure, and high energy dissipation ratio. The minimum wall pressure coefficient of an orifice plate can indirectly reflect its cavitation characteristics： the lower the minimum wall pressure coefficient is, the better the ability of the orifice plate to resist cavitation damage is. Thus, it is important to study the minimum wall pressure coefficient of the orifice plate. In this study, this coefficient and related parameters, such as the contraction ratio, defined as the ratio of the orifice plate diameter to the flood-discharging tunnel diameter; the relative thickness, defined as the ratio of the orifice plate thickness to the tunnel diameter; and the Reynolds number of the flow through the orifice plate, were theoretically analyzed, and their relationships were obtained through physical model experiments. It can be concluded that the minimum wall pressure coefficient is mainly dominated by the contraction ratio and relative thickness. The lower the contraction ratio and relative thickness are, the larger the minimum wall pressure coefficient is. The effects of the Reynolds number on the minimum wall pressure coefficient can be neglected when it is larger than 10^5. An emoirical expression was presented to calculate the minimum wall oressure coefficient in this study.

On grey relation projection model based on projection pursuit

Multidimensional grey relation projection value can be synthesized as one-dimensional projection value by using projection pursuit model. The larger the projection value is,the better the model. Thus,according to the projection value,the best one can be chosen from the model aggregation. Because projection pursuit modeling based on accelerating genetic algorithm can simplify the implementation procedure of the projection pursuit technique and overcome its complex calculation as well as the difficulty in implementing its program,a new method can be obtained for choosing the best grey relation projection model based on the projection pursuit technique.

具有系数相关性的可变分数时延滤波器设计方法

针对可变分数时延滤波器设计中的复杂度问题提出一种设计方法,将时域插值与泰勒级数展开相结合对Farrow结构进行系数配置,推导出相应的滤波器系数相关公式。该方法设计出的滤波器具有系数相关性,可使近一半滤波器系数独立,并得到低复杂度的滤波器实现结构。从复杂度、幅频响应及群时延、误差方面进行理论推导和仿真验证,分析结果表明,所提方法能有效降低可变分数时延滤波器的复杂度和计算成本。

基于范数灰关联-动态功效系数法的机坪U型区空间效率评估

为了确定机坪U型区空间效率评估指标体系及其指标的重要程度,分别从机坪设计和机坪运行两个维度建立机坪U型区空间效率评估指标体系。基于此提出了基于范数灰关联-动态功效系数法的机坪U型区空间效率评估方法。并以10个国内大型运输机场航站楼对应的U型区机坪为例进行计算,得到了影响机坪U型区空间效率各指标的权重及各机场航站楼对应的U型区机坪的空间效率评分。提出在U型区设计时应着重考虑指廊边机位个数、U型区指廊纵深和U型区底边长度3个指标。结果表明,该方法能够较为科学地对机坪U型区空间效率影响因素进行综合分析,有效评判不同构型机坪U型区空间效率。

武汉都市圈乡村地域系统结构与功能演变及耦合优化

研究目的:基于“人—地—域”与“三生空间”视角,分析2010—2020年武汉都市圈乡村地域系统结构与功能的时空演变特征,系统探讨结构与功能的耦合关系及其优化路径。研究方法:指标评价法和弹性系数模型。研究结果:(1)武汉都市圈乡村地域系统结构与功能指数空间格局相对稳定,2010—2020年结构与功能指数整体呈现波动上升趋势。(2)根据结构与功能指数变化及弹性系数的组合特征,将武汉都市圈乡村地域划分为6种类型。(3)协调增长区应找准特色发展主轴,巩固脱贫攻坚成果;双减区应变被动虹吸为主动承接,依托特色引领产业发展;结构滞后增长区和结构减—功能增反向区应借助区位优势打造品牌,实现转型发展;功能滞后增长区和结构增—功能减反向区应推动农村农业现代化,改善农村人居环境。研究结论:乡村地域系统结构与功能存在显著的阶段性和分异性耦合特征,通过制定针对性分区优化策略,促进乡村地域系统结构与功能的协调发展。

一般情况下一维三原子链的求解及其色散关系

求解一般情况下一维三原子链的色散关系,讨论恢复力系数对色散关系的影响规律.研究结果表明,一般情况下一维三原子链不同的原子间恢复力系数对各支格波的频率、频谱宽度以及频率禁带宽度的影响规律均表现出不同特点,可实现对频率禁带宽度的精细调节.本文的相关研究结果是对固体物理学基础理论的深入探讨,可为带通滤波器的工程设计提供理论指导.

运动想象同步视听刺激的脑电特征研究

目的基于运动想象(MI)的主动康复有助于感觉运动皮层重塑,探讨视听觉引导下的感觉运动皮层活跃度及其相关性,为视听辅助MI提供神经生理学依据。方法训练时受试者想左侧上肢做屈肘抬臂动作,同步观看相应动作的视频或语音指令,构成左侧抬臂动作的视觉引导或听觉引导。提取MI脑电信号(EEG)μ节律事件相关去同步(ERD)频带能量在关联脑区的变化率和感觉运动皮层脑区节点各通道之间的多元功率谱相关系数,分别表征大脑感觉运动皮层活性和相关性。结果对比MI、MI+视觉引导、MI+听觉引导和MI+视听引导之间特征变化的实验结果表明,EDR测度:MI+视听引导>MI+视觉引导>MI+听觉引导>MI,多元功率谱相关系数:C4通道与O1、Oz、O2通道,MI+视听引导组最高,MI+视觉引导组次之,其余两组之间没有明确的差异;C4通道与T7、T8通道,MI+听觉引导组最高,MI+视听引导组次之,其余两组之间没有明确的差异;O1、Oz、O2通道与T7、T8通道,MI+视听引导组最高,其余三组之间没有明确的差异。结论MI同步辅以想象动作的视听觉刺激能明显促进感觉运动皮层活性,强化皮层之间相关性,尤以MI+视听引导更为显著。

风电技术监督数据的采样频率确定方法研究

为降低网络专线的数据传输负荷,以一次调频技术监督指标为具体对象,研究了风电技术监督数据的采样频率确定方法。首先,通过一次调频数据段辨识得到风电场的一次调频过程单机等值动态模型,并估计实发功率的噪声方差。其次,以噪声方差估计值构造输出量测噪声,得到动态模型在典型输入下的输出信号。然后,以输入和输出信号在不同采样频率下的样本序列,得到一组技术监督指标估计值。最后,重复上述步骤,得到多组一次调频技术监督指标估计值,并以估计值变异系数小于给定阈值时的最小采样频率作为技术监督数据的采样频率。所提方法实现了技术监督指标估计值与数据采样频率间的关联。该研究对促进技术监督数据采集工作的发展有重要的意义。

钢管混凝土短柱轴压承载力试验与规范计算方法对比研究

为研究钢管混凝土构件尺寸效应对其承载力与规范计算方法的异同,对含钢率和套箍系数相同,截面形式不同的三种钢管混凝土短柱构件进行轴压试验,分别获取了构件在轴心压力作用下的荷载-应变关系曲线和荷载-轴向位移全过程曲线。运用叠加原理理论分析了当套箍系数相等时,不同规格钢管混凝土构件的受力性能和极限承载力提高效果。将试验值与现行规范计算值对比,研究结果表明,现有规范CECS 28:2012和DBJ 13-51—2010对钢管混凝土短柱的承载力计算值与试验值最接近;当套箍系数相等,材料性能相同、构件几何尺寸近似的圆钢管混凝土短柱具有一定的尺寸效应。

基于同态加密的电力调度数据抗泄露加密系统设计

电力调度数据需满足端到端转发的高转发率和低延迟要求,面对海量调度数据,在电力内网和外网的复杂体系中,各层数据易出现丢失、篡改等问题。为避免信息泄露事件的出现,设计一种基于同态加密的电力调度数据抗泄露加密系统。通过建立密码模板,联合获取明文样本,求解边缘加密系数取值范围,完成电力调度数据同态加密方案的制定。将File设备中存储的电力调度数据按需分配至上机位、下机位布局环境中,调节各级设备模块的运行状态,完成电力调度数据抗泄露加密系统设计。实验结果表明,该设计系统可有效保证明文样本与密文样本之间的对应编译关系,其对应编译关系准确率达到100%。在解决信息泄露问题方面具有突出价值。

多模态超声评估代谢相关脂肪性肝病脂肪变性的研究

目的探讨多模态超声检查在早期评估单纯性代谢相关脂肪性肝病(MAFLD)脂肪变性的应用价值。方法回顾性分析2021年10月~2022年11月于华北理工大学附属医院就诊的单纯性MAFLD患者(MAFLD组)161例及健康体检者(对照组)54例。所有研究对象均行核磁共振(MRI)、肝脏质子密度脂肪分数(PDFF)成像及超声衰减系数成像(ATI)、剪切波弹性成像(SWE)、剪切波频散成像(SWD)检查。以MRI-PDFF诊断结果确定研究对象是否有肝脏脂肪变性。应用受试者工作特征(ROC)曲线评价ATI参数、SWE参数、SWD参数及其联合诊断肝脏脂肪变性的诊断效能。结果MAFLD组ATI、SWE、SWD参数均高于对照组,超声定量指标诊断MAFLD脂肪变性的最佳截断值:ATI为0.635dB/(cm·MHz),SWE为6.15kPa,SWD为12.91(m/s)/kHz;ATI+SWD联合诊断模型的最佳截断值为0.673。对应的ROC曲线下面积(AUC)分别为0.950、0.644、0.631、0.950(P<0.05)。结论多模态超声检查技术可用于早期诊断单纯性MAFLD脂肪变性;ATI检查是较为准确、简单、便捷的检查方法,其单独诊断效能与ATI+SWD的联合诊断效能相当。

Multi-Criteria Decision Making Based on Correlation Coefficient of Triangular Intuitionistic Fuzzy Numbers

We study a multi-criteria fuzzy decision-making method based on weighted triangular intuitionistic fuzzy number correlation coefficients. Under the scenario that criteria weights for alternatives are completely unknown, triangular intuitionistic fuzzy method can not only supplement the insufficiency of the method based on the distance but also endow more information to the estimation and reduce the loss of evaluation information.Among the triangular numbers, two boundary numbers are the maximum and minimum values of the interval respectively, and the medium number is the most possible value under subjective estimation. Using this method,we propose a new way to obtain the criteria weights with more information quantity. By ranking the relative closeness of the weighted correlation coefficients between each alternative, and the critical and ideal alternatives,we show the method to figure out the most suitable alternative based on the expected criteria. An illustrative example is also taken into account to prove the effectiveness of the model.

基于灰色关联分析法的物联网数据异常检测方法

物联网数据具有构成复杂、规模庞大、异常形式多样化的特征,导致基于传统异常检测方法得到的结果正确率偏低。文中提出了一种基于灰色关联分析法的物联网数据异常检测方法。该方法利用灰色关联模型计算得到灰色关联系数,对原始物联网数据中的自有变量相关性进行排序,随后采用前向选择法进行变量排序选择,确定反推得到的特征参数误差达到最小值时的变量,并将其作为最优变量子集;在异常检测阶段,用最优变量子集对物联网数据进行异常位置寻优,实现异常检测。测试结果表明,该方法在不同攻击下,异常数据检测结果的F1值未出现明显的波动,对应的F1值为0.84~0.90。