Analysis of steady heat conduction for 3D axisymmetric functionally graded circular plate

The thermal conduction behavior of the three-dimensional axisymmetric functionally graded circular plate was studied under thermal loads on its top and bottom surfaces. Material properties were taken to be arbitrary distribution functions of the thickness. A temperature function that satisfies thermal boundary conditions at the edges and the variable separation method were used to reduce equation governing the steady state heat conduction to an ordinary differential equation （ODE） in the thickness coordinate which was solved analytically. Next, resulting variable coefficients ODE due to arbitrary distribution of material properties along thickness coordinate was also solved by the Peano-Baker series. Some numerical examples were given to demonstrate the accuracy, efficiency of the present model, mad to investigate the influence of different distributions of material properties on the temperature field. The numerical results confirm that the influence of different material distributions, gradient indices and thickness of plate to temperature field in plate can not be ignored.

AXISYMMETRIC BENDING OF TWO-DIRECTIONAL FUNCTIONALLY GRADED CIRCULAR AND ANNULAR PLATES

Assuming the material properties varying with an exponential law both in the thick- ness and radial directions, axisymmetric bending of two-directional functionally graded circular and annular plates is studied using the semi-analytical numerical method in this paper. The deflections and stresses of the plates are presented. Numerical results show the well accuracy and convergence of the method. Compared with the finite element method, the semi-analytical nu- merical method is with great advantage in the computational efficiency. Moreover, study on ax- isymmetric bending of two-directional functionally graded annular plate shows that such plates have better performance than those made of isotropic homogeneous materials or one-directional functionally graded materials. Two-directional functionally graded material is a potential alternative to the one-directional functionally graded material. And the integrated design of materials and structures can really be achieved in two-directional functionally graded materials.

Several three-dimensional solutions for transversely isotropic functionally graded material plate welded with circular inclusion

The problem of a transversely isotropic functionally graded material （FGM） plate welded with a circular inclusion is considered. The analysis starts with the general- ized England-Spencer plate theory for transversely isotropic FGM plates, which expresses a three-dimensional （3D） general solution in terms of four analytic functions. Several analytical solutions are then obtained for an infinite FGM plate welded with a circular inclusion and subjected to the loads at infinity. Three different cases are considered, i.e., a rigid circular inclusion fixed in the space, a rigid circular inclusion rotating about the x-, y-, and z-axes, and an elastic circular inclusion with different material constants from the plate itself. The static responses of the plate and/or the inclusion are investigated through numerical examples.

On asymmetric bending of functionally graded solid circular plates

Based on the three-dimensional elasticity equations, this paper studies the elastic bending response of a transversely isotropic functionally graded solid circular plate subject to transverse biharmonic forces applied on its top surface. The material prop- erties can continuously and arbitrarily vary along the thickness direction. By virtue of the generalized England＇s method, the problem can be solved by determining the expres- sions of four analytic functions. Expanding the transverse loarl in Fourier series along the circumferential direction eases the theoretical construction of the four analytic functions for a series of important biharmonic loads. Certain boundary conditions are then used to determine the unknown constants that are involved in the four constructed analytic functions. Numerical examples are presented to validate the proposed method. Then, we scrutinize the asymmetric bending behavior of a transversely isotropic functionally graded solid circular plate with different geometric and material parameters.

Semi-analytical weight function method for center-cracked circular disk subjected to diametral compression

Büeckner Rice weight function method was used to analyse mixed mode fracture of center cracked circular disk subjected to uniaxial compression. Based on Wu Carlsson procedure semi analytical modes Ⅰ and Ⅱ weight functions were derived from corresponding reference displacement fields and stress intensity factors calculated by finite element method. Normalized mode Ⅰ and mode Ⅱ stress intensity factors, f Ⅰ, f Ⅱ , were derived from the obtained semi analytical weight functions. The results were then fitted into polynomials, the precision is within 0.5%. It is interesting to note that when the inclined angle θ of a crack is less than 15°, the f Ⅰvalues are positive. when θ =15°, the f Ⅰ values are positive for the crack length a varying from 0.1 to 0.7, but when a =0.8, the f Ⅰ takes the negative value -0.51. When θ >15°, all the f Ⅰ values become negative, which denotes that the compression shear mode is achieved at crack tips. These results are very useful in the investigation of mixed mode fracture of brittle materials.

环状RNA在雌性家畜生殖过程中的表达及作用研究进展

环状RNA(circular RNA,circRNA)是由线性前体mRNA通过反向剪接产生的一种单链共价闭合的环状长链非编码RNA分子,参与调节真核生物的基因表达。随着高通量测序技术的发展,越来越多的circRNA在雌性哺乳动物生殖系统中被发现,但其在动物生殖发育过程中的功能研究尚处于起步阶段。本文就circRNA的形成、特点、功能及其在雌性家畜生殖过程中的作用进行综述,以期为深入探究circRNA调控雌性家畜生殖发育的机制奠定理论基础。

外周血环状RNA hsa_circRNA_000581表达水平与急性缺血性脑卒中痰证的关联研究

目的 探讨外周血环状RNA hsa_circRNA_000581表达水平与急性缺血性脑卒中(AIS)痰证的关系。方法 选取2016年1月至2020年12月广西中医药大学第一附属医院收治的AIS患者171例为AIS组。选取同期与AIS组来源医院同城区的社区卫生服务中心招募的中国汉族一般人群182例为对照组。通过实时荧光定量聚合酶链反应技术检测研究对象外周血hsa_circRNA_000581相对表达水平。采用受试者工作特征曲线分析hsa_circRNA_000581表达水平对AIS的诊断价值。分析hsa_circRNA_000581在对照组和不同中医证候要素患者外周血中的表达水平,并比较AIS痰证患者hsa_circRNA_000581高表达组与低表达组的血常规及凝血功能指标。结果 AIS组外周血hsa_circRNA_000581表达水平显著低于对照组[4.43×10^(-4)(2.90×10^(-4),7.14×10^(-4))比6.84×10^(-4)(4.08×10^(-4),1.01×10^(-3))](P<0.001)。外周血hsa_circRNA_000581表达水平诊断AIS的曲线下面积为0.657,敏感度为69.1%、特异度为62.0%。AIS痰证组(n=68)的外周血hsa_circRNA_000581表达水平显著低于对照组(P=0.004),但AIS风证组(n=55)的hsa_circRNA_000581表达水平与对照组比较差异无统计学意义(P=0.068)。hsa_circRNA_000581低表达组(n=34)AIS痰证患者的血小板计数和纤维蛋白原水平显著高于高表达组患者(n=34),差异均有统计学意义(P=0.041、P=0.022)。结论 环状RNA hsa_circRNA_000581可能通过影响凝血功能而影响AIS痰证的发生。

天麻钩藤饮加减联合电针治疗急性脑梗死下肢偏瘫合并高血压临床研究

目的:观察天麻钩藤饮加减联合电针对急性脑梗死下肢偏瘫合并高血压患者偏侧下肢神经功能及血流变化的影响。方法:收集肝阳上亢型急性脑梗死下肢偏瘫合并高血压患者242例,采用随机数字表法分为基础治疗组62例、中药组61例、电针组58例、联合组61例,基础治疗组给予降压、抗血小板、降脂稳斑、改善循环、清除自由基等基础治疗,在此基础上,中药组加服天麻钩藤饮加减方,电针组加用电针治疗,联合组同时加以天麻钩藤饮加减方及电针治疗。治疗2周、4周后分别对患侧下肢运动功能、感觉功能、平衡功能进行评估,同时记录患侧下肢胫后(PT)动脉峰值流速、足背(DP)动脉峰值流速,评估患者下肢神经功能和血流变化情况。结果:重复测量方差分析显示,治疗后,各组患者下肢运动功能、平衡功能、感觉功能、PT动脉峰值流速、DP动脉峰值流速均较治疗前有所改善(P<0.05)。析因设计方差分析显示,治疗2周、4周后,中药组、电针组运动功能均有明显改善(P<0.05);治疗4周后电针组感觉功能明显改善(P<0.05),中药组平衡功能显著改善(P<0.05);治疗2周、4周后中药组PT、DP动脉峰值流速均明显改善(P<0.05),电针组未见明显变化(P>0.05)。结论:天麻钩藤饮加减方联合电针治疗可明显改善患者下肢运动功能、感觉功能及平衡功能,提高下肢动脉峰值流速,有效改善急性脑梗死患者患侧下肢的神经功能及循环功能。

老年急性脑梗死患者血清circTTC3和miR-138-5p水平变化及意义

目的探究老年急性脑梗死(ACI)患者血清环状RNA TTC3(circTTC3)和微小RNA-138-5p(miR-138-5p)水平变化及意义。方法选取2021年9月—2023年9月四川大学华西医院老年医学中心/干部医疗科诊治老年ACI患者128例(ACI组),根据美国国立卫生研究院卒中量表(NIHSS)分为轻度亚组42例、中度亚组49例和重度亚组37例,同期医院门诊体检的健康人员120例作为健康对照组;采用实时荧光定量PCR法测定血清circTTC3和miR-138-5p表达水平,Pearson法分析老年ACI患者血清circTTC3和miR-138-5p的相关性,Spearman法分析老年ACI患者血清circTTC3和miR-138-5p表达水平与NIHSS评分相关性,受试者工作特征(ROC)曲线分析血清circTTC3和miR-138-5p表达水平对老年ACI患者神经缺损程度的诊断价值。结果与健康对照组比较,ACI组血清circTTC3表达水平升高,miR-138-5p降低(t/P=17.207/<0.001、16.239/<0.001)。血清circTTC3水平比较,轻度亚组<中度亚组<重度亚组,miR-138-5p表达水平比较,轻度亚组>中度亚组>重度亚组(F/P=26.579/<0.001、105.935/<0.001)。老年ACI患者血清circTTC3表达水平与NIHSS评分呈正相关(r=0.521,P<0.001),与大脑中动脉(MCA)、大脑前动脉(ACA)血流速度呈负相关(r=-0.425、-0.392,P均<0.001);miR-138-5p表达水平与NIHSS评分呈负相关(r=-0.785,P<0.001),与MCA、ACA血流速度呈正相关(r=0.571、0.635,P均<0.001)。circTTC3、miR-138-5p及二者联合诊断ACI神经缺损程度的AUC分别为0.817、0.810、0.878,二者联合诊断价值优于单独诊断(Z/P=2.106/0.035、2.406/0.016)。结论老年ACI患者血清circTTC3表达水平升高,miR-138-5p表达水平降低,二者与患者病情的严重程度密切相关,可能作为ACI病情诊断、治疗相关的作用靶点。

非圆形隧洞衬砌支护下应力与位移的新解法

以往在利用平面弹性复变函数方法进行衬砌支护作用下非圆形隧洞的力学分析时,一般将洞室外域保角映射到象平面的单位圆外域,并认为可以利用同一个映射函数将衬砌截面映射到象平面的圆环域内。当衬砌厚度很薄时,这种方法是可行的,而当衬砌相对较厚时,利用同一映射函数所得到的衬砌截面形状发生严重失真。为解决此问题,本文引入两套映射函数,分别将洞室外域映射到象平面的单位圆的圆外域,衬砌截面映射到圆环域。这种方法可以适应于不同的衬砌厚度,利用这种方式获得的衬砌截面,在衬砌较厚时仍能保证衬砌厚度相对均匀。在求解解析函数过程中不再采用传统的幂级数解法,而是使用边界配点法,将两套映射函数结合,获得了该问题的应力解和位移解。本文以马蹄形隧洞为例,求解结果与ANSYS软件所得数值解吻合很好,分析了衬砌厚度对隧洞应力和位移的影响。根据本文解答可以方便、快捷地进行相近条件下隧道的初步设计。

磁电弹性材料中圆弧形裂纹的反平面断裂问题

利用广义复变函数理论和保角映射技术,研究磁电弹性复合材料中圆弧形裂纹在无穷远处受到沿磁电极化方向的磁/电载荷和反平面机械载荷的共同作用下的反平面问题,给出应力场及位移场的精确解析解,并获得在磁电全非渗透及全渗透边界条件下圆弧裂纹尖端场强度因子和能量释放率的解析解。基于数值解进行数值分析,由数值结果表明:控制圆弧形裂纹半弦长与弓高比值的减少,可以提高材料的可靠性能;在两种边界条件下,机械载荷的不断增加最终会促进裂纹的扩展;在磁电全渗透边界条件下,裂纹扩展不受磁/电载荷的影响,但与材料常数和机械载荷的大小水平有关;在磁电全非渗透边界条件下,正(负)磁/电载荷的增加会阻碍裂纹扩展。

基于模糊聚类的蓝莓成熟分级无损检测应用研究

由于现有的水果成熟分级技术通用性不够,不能对蓝莓成熟进行有效分级。因此提出基于模糊聚类的蓝莓成熟分级方法。通过图像处理技术分别对蓝莓的面积、周长、圆形度和着色分布进行计算,最后确定蓝莓成熟隶属函数和分级标准。试验表明,基于模糊聚类的蓝莓成熟分级方法能够有效地、快速地对蓝莓进行分级,其准确率为90%。

基于脉冲耦合神经网络的红外图像分割算法研究

红外图像噪声多、结构复杂,传统的分割方法难以对红外图像实现完整的分割。脉冲耦合神经网络(PCNN)参数众多,而人工调整网络参数耗时耗力。为了避免人工调整网络参数、实现对红外图像较完整的分割,将粒子群优化(PSO)算法和改进的PCNN相结合,提出了一种新的红外图像分割算法。首先,对红外图像进行预处理。其次,为了减少网络参数,对PCNN进行了化简。然后,将预处理图像输入网络进行循环迭代,利用PSO算法计算每次迭代的分割结果的适应函数值,从而确定群体和个体最佳参数。最后,通过种群最佳参数得到分割结果。为了验证算法的分割性能,试验使用了不同的自然风景图像和红外图像。试验结果表明,所提算法可以对红外和自然风景图像实现较完整的分割;无论是分割效果还是定性分析,所提算法都要优于传统算法。

Diffraction of plane SH waves by a semi-circular cavity in half-space

This paper presents a closed-form solution for diffraction of plane SH waves by a semi-circular cavity in half-space by using wave function expansion method. Accuracy of the solution is checked by the displacement residual and stress residual along the boundaries. Numerical results show that there are notable differences for response amplitudes between a semi-circular cavity and a whole-circular cavity in a half-space.

NEW SOLUTION SYSTEM FOR CIRCULAR SECTOR PLATE BENDING AND ITS APPLICATION

Instead of the biharmonic type equation, a set of new governing equations and solving method for circular sector plate bending is presented based on the analogy between plate bending and plane elasticity problems. So the Hamiltonian system can also be applied to plate bending problems by introducing bending moment functions. The new method presents the analytical solution for the circular sector plate. The results show that the new method is effective.

ANALYSIS OF THE DYNAMIC STABILITY OF ELECTRICAL GRADED PIEZOELECTRIC CIRCULAR CYLINDRICAL SHELLS

A system of Mathieu–Hill equations have been obtained for the dynamic stability analysis of electrical graded piezoelectric circular cylindrical shells subjected to the combined loading of periodic axial compression and radial pressure and electric ?eld. Bolotin’s method is then employed to obtain the dynamic instability regions. It is revealed that the piezoelectric e?ect, the piezoelectric graded e?ect and the electric ?eld only have minor e?ect on the unstable region. In contrast, the geometric parameters, the rigidity of constituent materials and the external loading play a dominant role in determining the unstable region.

Statics of FGM circular plate with magneto-electro-elastic coupling:axisymmetric solutions and their relations with those for corresponding rectangular beam

This paper investigates the static behavior of a functionally graded circular plate made of magneto-electro-elastic（MEE） materials under tension and bending.The analysis is directly based on the three-dimensional governing equations for magnetoelectro-elasticity, with the boundary conditions on the upper and lower surfaces satisfied exactly and those on the cylindrical surface satisfied approximately（in the Saint Venant sense）. The analytical solutions, derived with a direct displacement method, are valid for any functionally graded material（FGM） with its properties varying independently in a continuous manner along the thickness direction. For homogeneous materials, these solutions are degenerated to the ones available in the literature. Interesting relations are also found between the solutions for a functionally graded magneto-electro-elastic（FGMEE） circular plate and those for an FGMEE rectangular beam, and even those for a functionally graded elastic beam when only the elastic displacements are considered. The beam solutions are also derived using a direct displacement method. Numerical examples are presented to verify the present analytical solutions, show the effects of material heterogeneity and multi-field coupling, and indicate the correspondence between the plate solutions and beam solutions.

AN ELASTICITY SOLUTION FOR AXISYMMETRIC PROBLEM OF FINITE CIRCULAR CYLINDER

In this paper the complete double-series in the closed region expressing the double-variable functions and their partial derivatives are derived by the H-transforniution and Stockes transformation. Using the double-series, a series solution for the axisyinmetric boundary value problem of the elastic circular cylinder with finite length is presented.In a numerical example, the cylinder subjected to the axisymmetric traellens with various loaded regions is investigated and the distributions of the displacement sand stresses are obtained.It is possible to solve the axisymmetric boundary value problems in the eylinderical coordinates for other scientific fields by use of the method presented in this paper.

Thermal buckling and postbuckling of FGM circular plates with in-plane elastic restraints

Based on von Karman＇s plate theory, the axisymmetric thermal buckling and post-buckling of the functionally graded material （FGM） circular plates with in- plane elastic restraints under transversely non-uniform temperature rise are studied. The properties of the FGM media are varied through the thickness based on a simple power law. The governing equations are numerically solved by a shooting method. The results of the critical buckling temperature, post-buckling equilibrium paths, and configurations for the in-plane elastically restrained plates are presented. The effects of the in-plane elastic restraints, material property gradient, and temperature variation on the responses of thermal buckling and post-buckling are examined in detail.

The quantum spectra analysis of the circular billiards in wells

We use a recently defined quantum spectral function and apply the method of closed-orbit theory to the 2D circular billiard system. The quantum spectra contain rich information of all classical orbits connecting two arbitrary points in the well. We study the correspondence between quantum spectra and classical orbits in the circular, 1/2 circular and 1/4 circular wells using the analytic and numerical methods. We find that the peak positions in the Fourier- transformed quantum spectra match accurately with the lengths of the classical orbits. These examples show evidently that semi-classlcal method provides a bridge between quantum and classical mechanics.