常规二维超声和弹性成像超声检查对甲状腺乳头状癌患者的诊断效果

目的:对常规二维超声与弹性成像超声检查在甲状腺乳头状癌患者中的应用效果予以分析。方法:随机选取我院2019年8月至2020年2月间收治的甲状腺乳头状癌患者60例,所有患者均予以常规二维超声与弹性成像超声检查,对比两种方法的诊断准确率。结果:弹性成像超声检查准确率明显高于常规二维超声,P<0.05,差异有统计学意义。结论:在甲状腺乳头状癌患者的诊断中,相对于常规二维超声,弹性成像超声检查诊断准确率更高,值得在临床应用中推广。     

二维超声联合实时组织弹性成像鉴别诊断乳腺癌腋窝淋巴结转移的价值

目的:评估腋窝淋巴结有无转移对乳腺癌患者的分期和治疗起着至关重要的作用.建立实时弹性成像评分法和二维超声评估乳腺癌患者腋窝淋巴结有无转移的改良评分系统.方法:对纳入的已确诊的92例乳腺癌患者的97个可疑腋窝淋巴结进行二维超声和实时组织弹性超声检查.二维超声基于5个特征,分别为淋巴结短径、长短径比(L/S)、边界、皮质厚...     

基于GPU的超声弹性成像并行实现研究

为了提高超声弹性成像计算速度,提出使用GPU硬件加速基于互相关技术和相位零估计的弹性成像技术。先描述这两种弹性成像技术的实现细节及特点,然后分析这两种技术的计算密集操作部分的并行化计算可能性,最后通过GPU程序开发工具ArrayFire实现了基于GPU的互相关和相位零估计的超声弹性成像技术。通过模拟和扫描仿真人体组织的弹性成像体模获得的压缩前后数据帧对基于GPU的超声弹性成像方法进行测试与验证。实验结果表明,基于GPU的方法可以大幅提高弹性图计算速度,在处理单帧弹性图条件下,与基于互相关方法比较,加速比达到42,而基于相位零估计的方法在提高数据吞吐量的情况下加速比可达到65。     

二维接触问题的变形混合求解方法

提出一种接触问题的变形混合求解方法。根据接触应力的Ｈｅｒｔｚ分布，按照一定的离菜度，计算出接触宽度方向上的等效离散分布载荷，运用有限元分析软件建模、计算，可较精确地求出变形结果。该方法综合应用弹性力学方法和有限元分析软件，具有精度高和使用方便的特点。     

二维二轴编织复合材料几何模型及弹性性能预测

提出了二维二轴1×1和2×2编织复合材料的几何模型,模型考虑了纤维束的相互挤压及横截面的变化。基于细观分析和体积平均法,建立了预测二维二轴编织复合材料弹性性能的理论分析方法。数值结果与试验结果吻合,表明该方法行之有效,且具有运算快、精度高、适合工程分析等优点。分析了编织角、纤维体积含量和纤维束横截面形状对材料弹性常数的影响。研究表明,编织角对弹性常数的影响具有互补性,材料弹性模量与纤维体积含量成正比,纤维束截面形状变化对材料弹性常数影响不大。     

基于信号相关法的材料弹性常数无损测量

研究了信号相关法在超声法材料声弹性常数测量中回波时间差的自动识别计算.通过计算机模拟的方法,分别采用信号插值、相关系数拟合两种相关系数峰值提取方法,对相关运算算法的精度、抗噪声能力、稳定性进行了验证和比较.在实验部分通过计算横波、纵波在各向同性试件中传播的回波时间差,得出超声横波、纵波波速,根据声弹性理论最终计算出材料...     

基于自相关算法的自回归多普勒信号预测

超声多普勒系统中,脉冲多普勒采用分时设计将B模式成像和血流速度检测同时进行,导致了多普勒信号在成像阶段不可避免的缺失。为弥补由信号缺失所带来的信号不连续问题,降低对血流图像的干扰,一种基于自相关算法的多普勒信号预测方法在本文中被采用。     

二维弹性波散射时域Born近似

本文探讨了非零面积缺陷对一种典型脉冲波（称之为基脉冲）散射的正反问题。利用平面简谐波人射时弹性波散射场的频域Born近似解,通过Fourier变换,给出了散射体（或者说缺陷）对基脉冲入射时的脉冲响应函数（称之为基脉冲响应函数）,并通过Radon变换法建立了散射体特征函数与基脉冲响应函数的关系式,模拟识别结果表明时域Born近似方法对无损检测技术具有潜在的应用价值。     

一种有效压缩十字阵二维角估计计算量的方法

针对平面阵在二维方向角估计中运算量大、影响系统实时性的问题.利用十字阵为两个直线阵构成的特点,提出了一种新的十字阵二维谱估计方法.通过间接求解,将二维方向角估计转化为两个独立直线阵的一维角估计.此方法无需二维谱峰搜索,大大减少了运算量,提高了阵列的分辨力.计算机仿真验证了该方法的有效性.     

基于和表的互相关计算方法在超声弹性成像中的性能分析

互相关计算方法的性能对超声弹性成像运动的计算效率起着决定性的作用。在串行计算环境下,基于和表的快速互相关算法在维持计算精度的同时可以获得更快的计算效率。然而,在并行计算环境下,尤其是GPU平台上,基于和表的快速互相关算法的实现以及性能还没有相关的报道。在本研究中,以二维超声弹性成像的运动追踪应用为目标,基于和表的快速互相关算法(ST-NCC)在GPU平台上得以实现,并且从计算效率及计算精度和传统的互相关算法进行了详细比较。初步结果显示,虽然基于和表的快速互相关算法(ST-NCC)在串行计算环境下获得了较好的计算效率,但是在GPU环境下,两种方法的计算效率没有较大的差距。     

Simultaneous Estimation of Thermal Properties of Living Tissue Using Noninvasive Method

A new noninvasive measurement method is presented for simultaneous estimation of the key thermal properties of cylindrical living tissue. This method is based on heating of the surface of a cylinder and measuring surface temperatures at three points on the cylinder. Numerical calculations and theoretical analysis for the corresponding two-dimensional model are carried out. The results have demonstrated the feasibility of the proposed method. The selection, crossover, and mutation operators of a new real-coded genetic algorithm (GA) are designed in this paper to solve the problem of parameter optimization. Then, a set of simulations are performed to verify the effectiveness of the proposed method as well as to optimize the design of the experiments. Finally, a series of experiments is performed to measure the thermal parameters of the human forearm. The experimental results indicate that the obtained parameters, such as the thermal conductivity, blood perfusion, and volumetric heat capacity, are within the range of reference values. The proposed method is easy to implement in practical applications. Paper presented at the Seventeenth European Conference on Thermophysical Properties, September 5–8, 2005, Bratislava, Slovak Republic.     

Estimation of the Enhancement Factor for Mercury in Air

A combination of classical thermodynamics and molecular theory was used to calculate the enhancement factor (ratio of vapor-phase partial pressure to saturated vapor pressure) for liquid mercury in equilibrium with air at standard atmospheric pressure at temperatures from 0 °C to 40 °C. The enhancement factors range from 1.0025 at 0 °C to 1.0016 at 40 °C. This enhancement is too small in magnitude, and in the wrong direction, to explain a difference that has been noted between equilibrium vapor concentrations implied by the vapor pressure of pure mercury and those assumed in some calibration procedures.     

多项式展开参数识别

研究了散射体的参数识别问题，用有限元方法计算正问题，通过多项式展开待识别参数，运用这一策略，最终通过最小二乘法优化方法建立目标函数，叠代实现参数的识别。     

A Two-Dimensional Analytical Solution for the Transient Short-Hot-Wire Method

Unlike the conventional transient hot-wire method for measuring thermal conductivity, the transient short-hot-wire method uses only one short thermal-conductivity cell. Until now, this method has depended on numerical solutions of the two-dimensional unsteady heat conduction equation to account for end effects. In order to provide an alternative and to confirm the validity of the numerical solutions, a two-dimensional analytical solution for unsteady-state heat conduction is derived using Laplace and finite Fourier transforms. An isothermal boundary condition is assumed for the end of the cell, where the hot wire connects to the supporting leads. The radial temperature gradient in the wire is neglected. A high-resolution finite-volume numerical solution is found to be in excellent agreement with the present analytical solution.     

基于人体轮廓图像确定关节位置的方法

研究并提出了一种基于人体轮廓图像确定人体关节位置的方法。首先利用能量函数从人体轮廓中抽取人体的虚拟骨架,然后利用所定义的标准人体骨架模型中给出的确定人体虚拟骨架中的一个点是否为关节点的三个规则以及人体解剖学的相关知识确定关节的位置。实验结果表明,该算法行之有效。它无需对图像中的人体在运动和颜色等方面附加限制条件;同时,对人体轮廓图像中的噪声亦有很好的抑制作用,这一特点使得它对人体轮廓提取的精度要求较低,在复杂的背景下具有较的性能。     

对变频医用超声诊断仪超声源所属档次的判定方法

随着经济和科技的发展,越来越多的医用超声诊断仪超声源的频率呈现变频现象,本文针对出现的新情况,根据医用JJG639-2005《医用超声诊断仪超声源》检定规程,分析如何判定B超的所属档次。     

Mixed Fourier-Jacobi Spectral Method for Two-Dimensional Neumann Boundary Value Problems

In this paper, we propose a mixed Fourier-Jacobi spectral method for two dimensional Neumann boundary value problem. This method differs from the classical spectral method. The homogeneous Neumann boundary condition is satisfied exactly. Moreover, a tridiagonal matrix is employed, instead of the full stiffness matrix encountered in the classical variational formulation. For analyzing the numerical error, we establish the mixed Fourier-Jacobi orthogonal approximation. The convergence of proposed scheme is proved. Numerical results demonstrate the efficiency of this approach.     

Hot-Wire Method for Kinematic Viscosity Estimation

This paper explores the characterization of thermal and momentum diffusion properties of condensed phase biological fluids. The widely used transient hot-wire technique for determination of thermal diffusion properties is proposed here to investigate also the apparent kinematic viscosity of fluids with the apparatus commonly adopted for thermal conductivity and/or thermal diffusivity determination. The undesired onset of convection in the determination of thermal diffusion properties is in this case the useful effect measured at the wire–fluid interface. From a theoretical point of view, the onset of convection time at a given vertical position along the wire has been related to the Prandtl number, and the reliability of the kinematic viscosity has been studied and preliminarily tested in the case of water.     

Shanks' Method for Dynamic Phasor Estimation

A new algorithm for phasor estimation is proposed. It is based on a signal model that allows amplitude and phase dynamic variations. An autoregressive moving average (ARMA) model is assumed for the oscillating signal. Its autoregressive part is fixed, and it is defined only by the nominal fundamental frequency. Its best moving average parameters are estimated with Shanks' method. These parameters provide the key information from which the phasor state vector is estimated through the partial fraction expansion of the ARMA rational polynomial. These estimates could be useful, not only for the monitoring and controlling of the power system, but also for discriminating between a fault and an oscillation state.     

超声波骨密度仪校准方法的探讨

超声波骨密度仪的准确性对医院诊断治疗影响重大,建立一套完善的校准方法,定期开展对超声波骨密度仪进行校准是临床工作的当务之急.通过长期的实践摸索,我们对各种超声波骨密度仪进行了系统的测试和论证.初步建立了一套可靠的校准方法.该方法科学合理,简便易行,各项指标评价结果符合仪器的设计性能及实际测试工作要求,对医学临床及法定计量检定机构开展超声波骨密度仪的校准工作有一定的指导意义.