Analysis of a Cavity Used for Medical Purposes with the Dyadic Green's Functions and the Moment method

The structure of a microwave radiator used for medical purposes is described. The dyadic Green's function and the method are used to analyze this Kind of multimode rectangular medium-filled cavity. The distribution of electromagnetic field intensity and the power density,as well as the temperature effect in the biological sample load are obtained.OPtimization of the size of cavity and the position of the input aperture have been performed with the computer to optimize the uniformity or microwave effect and the input VSWR.Necessary experiments were performed to compare the data obtained with theoretical analysis.

不同内固定系统治疗股骨转子间骨折的力学稳定性

背景:股骨转子间骨折的骨折类型和固定方式多样,各固定系统间的力学稳定性相差较大。使用有限元分析方法对各固定系统开展生物力学研究具有科学的临床意义。目的:通过有限元方法对比分析多种内固定应用于股骨A031-A2.1型转子间骨折的力学稳定性。方法:在已验证有效性的股骨有限元模型基础上,对模型进行必要的切割,造模成股骨A031-A2.1型转子间骨折,模拟临床手术方法置入不同的内固定系统,分别建立股骨近端防旋髓内钉、动力髋螺钉、经皮加压钢板和股骨近端锁定钢板固定模型。约束4组模型股骨远端下所有节点,在股骨头上施加700,1400和2100N的压缩载荷,通过计算分析,观察各组模型的等效应力分布和压缩刚度,比较各组模型之间的力学稳定性。结果与结论:①通过计算分析,对比各组模型的变形量计算压缩刚度后,在各级载荷作用下,各组模型上压缩刚度呈现的趋势:生理组>股骨近端防旋髓内钉组>股骨近端锁定钢板组>经皮加压钢板组>动力髋螺钉组;完整的生理组模型的压缩刚度明显高于所有的手术组模型;②观察应力指标,因存在应力遮挡效应,致使各固定组的应力峰值均高于生理组,最大峰值均集中分布于各内固定上;其中股骨近端防旋髓内钉固定组应力峰值最小,动力髋螺钉固定组应力最高,应力分布趋势呈现:生理组<股骨近端防旋髓内钉固定组<经皮加压钢板固定组<股骨近端锁定钢板固定组<动力髋螺钉固定组;③分布于骨质模型的应力,因内固定置入位置不同呈现不同的分布结果;④提示对于股骨转子间骨折,各种内固定均能起到有效的固定,结合有限元分析结果得出股骨近端防旋髓内钉组是较好的一种内固定选择,呈现变形量小、应力峰值低,应力分布均匀的特性;经皮加压钢板组和股骨近端锁定钢板组的力学效果优良,固定效果接近股骨近端防旋髓内钉固定;动力髋螺钉固定效果欠佳,同比于其他内固定,其力学稳定性较差。

不同弹性模量计算机辅助设计和计算机辅助制造桩核材料的应力分析

背景:桩核修复是牙体缺损修复的一种常规选择,然而不同桩核材料的修复效果存在差异。目的:利用有限元方法评估不同弹性模量桩核修复模型中桩核与牙根黏结剂部位的应力分布情况。方法:在三维建模软件中构建一个三维根管治疗过的上颌中切牙模型,进行全瓷冠修复,修复中的桩核材料分别使用纳米陶瓷树脂(弹性模量12.8 GPa)、复合树脂(弹性模量16 GPa)、混合陶瓷(弹性模量34.7 GPa)、玻璃陶瓷(弹性模量95 GPa)、钛合金(弹性模量112 GPa)和氧化锆(弹性模量209.3 GPa),将模型约束在皮质骨中,在中切牙牙冠舌侧1/3处加载与牙体长轴呈45°的100 N集中力,通过最大主应力分析修复模型中桩核、牙本质及桩与牙根黏结剂的应力分布。结果与结论:(1)当使用弹性模量较高的桩核材料时,修复模型中的桩核应力较集中;当使用弹性模量接近牙本质的桩核材料(纳米陶瓷树脂和复合树脂)时,桩核的应力分布较均匀;无论桩核材料如何,各修复模型中牙本质上的应力分布相似;使用弹性模量更高的桩核时,修复模型中桩与牙根黏结剂处显示出更多的应力集中。(2)纳米陶瓷树脂模型中桩核、牙根及桩与牙根黏结剂处的最大应力值分别为31.00,33.21,0.51 MPa,复合树脂模型中桩核、牙根及桩与牙根黏结剂处的最大应力值分别为36.84,33.14,0.59 MPa,混合陶瓷模型中桩核、牙根及桩与牙根黏结剂处的最大应力值分别为64.05,32.83,1.00 MPa,玻璃陶瓷模型中桩核、牙根及桩与牙根黏结剂处的最大应力值分别为112.30,32.69,1.73 MPa,钛合金模型中桩核、牙根及桩与牙根黏结剂处的最大应力值分别为120.00,32.17,1.86 MPa,氧化锆模型中桩核、牙根及桩与牙根黏结剂处的最大应力值分别为148.80,31.85,2.28 MPa。(3)桩核材料的弹性模量越高,进行桩核修复时桩核处的最大应力值越大,桩核材料弹性模量对修复模型中桩与牙根黏结剂处与牙本质的最大应力值无明显影响。

Dynamic stiffness matrix of a poroelastic multi-layered site and its Green's functions

Few studies of wave propagation in layered saturated soils have been reported in the literature.In this paper,a general solution of the equation of wave motion in saturated soils,based on one kind of practical Blot's equation, was deduced by introducing wave potentials.Then exact dynamic-stiffness matrices for a poroelastic soil layer and half- space were derived,which extended Wolf's theory for an elastic layered site to the case of poroelasticity,thus resolving a fundamental problem in the field of wave propagation and soil-structure interaction in a poroelastic layered soil site.By using the integral transform method,Green's functions of horizontal and vertical uniformly distributed loads in a poroelastic layered soil site were given.Finally,the theory was verified by numerical examples and dynamic responses by comparing three different soil sites.This study has the following advantages:all parameters in the dynamic-stiffness matrices have explicitly physical meanings and the thickness of the sub-layers does not affect the precision of the calculation which is very convenient for engineering applications.The present theory can degenerate into Wolf's theory and yields numerical results approaching those for an ideal elastic layered site when porosity tends to zero.

ON REDUCIBILITY OF THE SELF-HOMOTOPY EQUIVALENCES OF WEDGE SPACES

Reducibility of the self-homotopy equivalences of wedge spaces is studied and some conditions implying the reducibility are obtained.

组织工程化口腔黏膜等效物的血管化特征

背景:前期研究中三维细胞重建组织工程化口腔黏膜等效物结构类似于正常口腔黏膜,即存在类上皮样结构、类固有层样结构、类血管腔样结构,并已初步实现了等效物的血管化建立,但其血管化特征尚不十分明确。目的:采用血管内皮细胞特异性标志物表达谱关联激光捕获显微切割系统靶向获取血管化口腔黏膜等效物的血管样结构,评价其成血管能力,揭示其血管化特征。方法:分别从人牙龈上皮组织和固有层组织原代培养人牙龈上皮细胞、人牙龈成纤维细胞、人牙龈间充质干细胞,人牙龈间充质干细胞经单克隆扩增培养后诱导分化形成血管内皮样细胞。将人牙龈上皮细胞、人牙龈成纤维细胞、血管内皮样细胞分层负载于脱细胞血管基质-0.25%类人Ⅰ型胶原支架上,构建血管化口腔黏膜等效物。将血管化口腔黏膜等效物(实验组)与脱细胞血管基质-0.25%类人Ⅰ型胶原支架(对照组)分别植入裸鼠背部皮下,14 d后两组切口表面涂布生物胶,实验组生物胶表面接种人牙龈上皮细胞,对照组不接种细胞,继续饲养14 d后取材,利用形态学观察口腔黏膜等效物分层结构;采用较为全面的血管内皮细胞特异性标志物表达谱对口腔黏膜等效物中的新生血管样结构进行免疫组化、免疫荧光标记,进行血管化特征分析;采用激光捕获显微切割系统靶向捕获免疫组化特异性标记的口腔黏膜等效物中新生血管样结构,靶向分析其血管化特征。结果与结论:(1)形态学观察显示口腔黏膜等效物细胞层次清晰,结构类似于正常口腔黏膜,即存在类上皮样结构、类固有层样结构、类血管腔样结构,类血管腔样结构内存在散在红细胞;(2)口腔黏膜等效物组中EdU Apollo示踪种子细胞结果显示:EdU Apollo 488标记的人牙龈上皮细胞呈绿色荧光表达;DAPI标记的人牙龈成纤维细胞呈蓝色荧光表达,体内形成类固有层样结构;Ed U Apollo 567标记的血管内皮样细胞呈红色荧光表达,体内形成类血管样结构;(3)血管内皮细胞特异性标志物表达谱免疫荧光标记血管结构显示,与正常口腔黏膜相比,口腔黏膜等效物中CD31、CD51、CD54、CD105、Tie-2、VWF、血管内皮生长因子受体1、血管内皮生长因子受体2表达升高(P<0.0001),CD34表达无明显变化(P>0.05);(4)与特异性标记的口腔黏膜血管结构相比,激光捕获显微切割系统靶向捕获的口腔黏膜等效物血管样结构中CD51、CD54、CD105、Tie-2、VWF、血管内皮生长因子受体1、血管内皮生长因子受体2表达升高(P<0.0001),CD31、CD34表达无明显变化(P>0.05);(5)结果表明,通过三维细胞分层重建的口腔黏膜等效物能够实现良好的血管化,其血管化特征符合新生血管生成的免疫学功能及特点;血管化助力三维细胞分层重建的口腔黏膜等效物再生。

Approximate trace and singleton failures equivalences for transition systems

Established system equivalences for transition systems, such as trace equivalence and failures equivalence, require the ob- servations to be exactly identical. However, an accurate measure- ment is impossible when interacting with the physical world, hence exact equivalence is restrictive and not robust. Using Baire met- ric, a generalized framework of transition system approximation is proposed by developing the notions of approximate language equivalence and approximate singleton failures （SF） equivalence. The framework takes the traditional exact equivalence as a special case. The approximate language equivalence is coarser than the approximate Slc equivalence, just like the hierarchy of the exact ones. The main conclusion is that the two approximate equiva- lences satisfy the transitive property, consequently, they can be successively used in transition system approximation.

Solutions of Green's function for Lamb's problem of a two-phase saturated medium

The solutions of Green’s function are significant for simplification of problem on a two-phase saturated medium.Using transformation of axisymmetric cylindrical coordinate and Sommerfeld’s integral,superposition of the influence field on a free surface,authors obtained the solutions of a two-phase saturated medium subjected to a concentrated force on the semi-space.

Parabose Coherent States Based on Green's Ansatz

The coherent states of parabose oscillator of order p based on the well-known Green's ansatz have been constructed. Furthermore, it is shown that the completeness relation for these coherent states may be expressed in the form of 2×2 matrix.

Lattice Green's Function for Infinite Square Lattice in the Second Nearest-Neighbour Interaction Approximation

In dealing with the square lattice model,we replace the traditionally needed Born-Von Karmann periodic boundary condition with additional Hamiltonian terms to make up a ring lattice.In doing so,the lattice Green's function of an infinite square lattice in the second nearest-neighbour interaction approximation can be derived by means of the matrix Green's function method.It is shown that the density of states may change when the second nearest-neighbour interaction is turned on.

Approximate Reachability and Bisimulation Equivalences for Transition Systems

Using Baire metric, this paper proposes a generalized framework of transition system approximation by developing the notions of approximate reachability and approximate bisimulation equivalences. The proposed framework captures the traditional exact equivalence as a special case. Approximate reachability equivalence is coarser than approximate bisimulation equivalence, just like the hierarchy of the exact ones. Both approximate equivalences satisfy the transitive property, consequently, they can be used in transition system approximation.

NEW TYPE OF DUAL BEM AND GREEN'S-FUNCTION-LIBRARY STRATEGY FOR FRACTURE ANALYSIS IN COMPLEX STRUCTURES

A new type of dual boundary integral equations(DBIE)is presented first,through which,a smaller system of equations needs to be solved in fracture analysis.Then a non-conforming crack tip element in two-dimensional problems is proposed.The exact formula for the hypersingular integral over the non-con- forming crack tip element is given next.By virtue of Green's-function-library strategy,a series of stress in- tensity factors(SIF)of different crack orientations,locations and/or sizes in a complicated structure can be obtained easily and efficiently.Finally,several examples of fracture analysis in two dimensions are given to demonstrate the accuracy and efficiency of the method proposed.

LEVEL SETS AND EQUIVALENCES OF MORAN-TYPE SETS

In the paper, we consider Moran-type sets E;given by sequences {a;};and{n;};. we prove that E;may be decompose into the disjoint union of level sets. Moreover,we define three type of equivalence between two dimension functions associated to two Morantype sets, respectively, and we classify Moran-type sets by these equivalent relations.

INVARIANTS UNDER STABLE EQUIVALENCES OF MORITA TYPE

The aim of this article is to study some invariants of associative algebras under stable equivalences of Morita type. First of all, we show that, if two finite-dimensional selfinjective k-algebras are stably equivalent of Morita type, then their orbit algebras are isomorphic. Secondly, it is verified that the quasitilted property of an algebra is invariant under stable equivalences of Morita type. As an application of this result, it is obtained that if an algebra is of finite representation type, then its tilted property is invariant under stable equivalences of Morita type; the other application to partial tilting modules is given in Section 4. Finally, we prove that when two finite-dimensional k-algebras are stably equivalent of Morita type, their repetitive algebras are also stably equivalent of Morita tvDe under cert..in conditions.

Formulation of Green's Function in Solving Schroedinger Equation forBipartite System with Kinetic Coupling Gained by Virtue of Entangled States

Using the entangled state representation we present a formulation of Green'sfunction in solving Schrodinger equation for bipartite system with kinetic coupling.

THE NUMERICAL SOLUTIONS OF GREEN'S FUNCTIONS FOR TRANSVERSELY ISOTROPIC ELASTIC STRATA

In this paper, a model of transversely isotropic elastic strata is used to simulate the soil layers situated on a half space. Instead of the half space, an artificial transmitting boundary is used to absorb the vibration energy. The displacement formulas at any soil layer interface under vertical or horizontal harmonic ring loads are obtained by using the thin layer element method. From these formulas, the explicit solutions of Green's functions_the displacement responses at any interface of these strata under vertical and horizon harmonic point loads_are derived. The examples show that the method presented in this paper is close to the theoretical method and the transversely isotropic property has evident influence on the Green's functions.

Characteristic analysis of scattering field in two-layer media by Green's function

The problem of three-dimensional(3D) acoustic scattering in a complex medium has aroused considerable interest of researchers for many years. An ultrasonic scattered field calculating technique is proposed to study the scattering echo from strongly scattered materials in a two-layer medium in this work. Firstly, with the high frequency stationary phase method,the Green's function of two-layer fluid media is derived. And then based on the idea of integral equation discretization,the Green's function method is extended to two-layer fluid media to derive the scattering field expression of defects in a complex medium. With this method, the scattering field of 3D defect in a two-layer medium is calculated and the characteristics of received echoes are studied. The results show that this method is able to solve the scattering P wave field of 3D defect with arbitrary shape at any scattering intensity in two-layer media. Considering the circumstance of waterimmersion ultrasonic non-destructive test(NDT), the scattering sound field characteristics of different types of defects are analyzed by simulation, which will help to optimize the detection scheme and corresponding imaging method in practice so as to improve the detection quality.

Complex fitting 3D closed-form Green's function and its application for silicon RF IC's

An approximate three-dimensional closed-form Green's function with the type of exponential function is derived over a lossy multilayered substrate by means of the Fourier transforms and a novel complex fitting approach. This Green's function is used to extract the capacitance matrix for an arbitrary three-dimensional arrangement of conductors located anywhere in the silicon IC substrate. Using this technique, the substrate loss in silicon integrated circuits can be analyzed. An example of inductor modeling is presented to show that the technique is quite effective.

GREEN'S FUNCTIONS OF INTERNAL ELECTRODES BETWEEN TWO DISSIMILAR PIEZOELECTRIC MEDIA

The generalized 2-D problem of a half-infinite interfacial electrode layer between two arbitrary piezoelectric half-spaces is studied. Based on the Stroh formalism, exact expressions for the (Green's) functions of a line force, a line charge and a line electric dipole applied at an arbitrary point near the electrode edge,were presented, respectively. The corresponding solutions for the intensity factors of fields were also obtained in an explicit form. These results can be used as the foundational solutions in boundary element method (BEM) to solve more complicated fracture problems of piezoelectric composites.

GREEN'S FUNCTIONS FOR A 2D ANISOTROPIC MEDIUM WITH A HYPERBOLIC BOUNDARY

By using Stroh's formalism and the conformal mapping technique,this paper derives simple exphcit Green's functions of a piezoelectric anisotropic body with a free or fixed hyperbolic boundary.The corresponding elastic fields in the medium are obtained,too.In particular,degenerated solutions of an ex- ternal crack from those of a hyperbolic problem are analysed in detail.Then the singular stress fields and the fracture mechanics parameters are found.The solutions obtained are valid not only for plane and antiplane problems but also for the coupled ones between inplane and outplane deformations.