超声表观积分背散射系数与骨矿密度的相关性分析

用超声评价骨质状况是近年来骨质疏松诊断方面的研究热点之一。介绍了超声背散射法及其参量表观积分背散射系数(Apparent Integral Backscatter coefficient,AIB)的测量及与骨矿密度(Bone Mineral Density,BMD)的相关性研究。在体采集了1087位志愿者跟骨的超声背散射信号,并用双能X射线骨密度仪(Dual X-ray Absorptiometry,DXA)测得腰椎和髋骨的BMD值,然后对AIB与BMD进行相关性分析。实验结果表明,参数AIB与BMD显著相关(R=0.58～0.64,n=1087,p<0.05),可被应用于松质骨状况评价。     

超声背散射信息熵成像评价脂肪肝的新方法

提出超声背散射Tsallis信息熵成像评价脂肪肝的新方法。利用滑动窗口法,估算窗口内局部背散射包络信号的Tsallis信息熵参数值,对信息熵参数值矩阵进行扫描变换、颜色映射及感兴趣区域设置,叠加到超声B模式图像,实现Tsallis信息熵成像。分析72名肝脏捐献者和204名患者的超声背散射信号,参考标准分别为磁共振波谱测得的肝脏脂肪分数(Hepatic Fat Fraction, HFF)和肝活检组织学检查测得的脂肪肝程度。对于72名肝脏捐献者,Tsallis信息熵与lg(HFF)的相关系数r=0.67(P<0.000 1)。对于204名患者,受试者工作特征曲线下面积分别为0.82、0.88、0.89(≥轻度、≥中度、≥重度),而超声背散射零差K成像分别为0.76、0.82、0.82。超声背散射Tsallis信息熵成像可以直观定征并定量评价脂肪肝的严重程度,其诊断性能优于超声背散射零差K成像,可作为一种超声评价脂肪肝的新方法。     

超声背散射信号评价皮肤烧伤程度的可行性研究

烧伤后的皮肤可分为烧伤层和健康组织层,两层间的阻抗差异将使超声脉冲在界面处发生散射,从而影响超声背散射信号及相关的参数。利用超声背散射技术,研究了新鲜带皮猪肉(皮肤+脂肪层+瘦肉层)烧伤程度与表观背散射系数(Apparent Backscatter Coefficient,ABC)、表观积分背散射系数(Apparent Integral Backscatter Coefficient,AIB)和频谱质心偏移量(Spectral Centroid Shift,SCS)的相关性。研究结果表明,烧伤级数和ABC、AIB参数都有很高的正相关性,说明将ABC和AIB用于评价烧伤程度是可行的。     

评价松质骨状况的一种背散射频谱方法

采用超声背散射信号的质心偏移量来评价松质骨,并对牛胫骨和人体跟骨中背散射信号的质心偏移量与松质骨表观密度的关系,以及人体跟骨松质骨中背散射信号频谱质心位置与年龄的关系进行了分析讨论。分析结果表明,随松质骨表观密度的增大,背散射信号频谱的质心向低频方向移动;随年龄的增大,质心位置越接近于发射超声的中心频率。根据超声背散射信号质心偏移量的大小,可用于评价松质骨健康状况。     

松质骨组织的若干超声参量成像方法

介绍了两种松质骨组织超声参量成像方法,即宽带超声衰减成像和超声传导速度成像,概述了这两种基于透射法的成像方法的基本原理以及应用情况．并指出了采用超声透射法参量成像时存在的问题。然后对基于背散射法的超声背散射系数成像方法的可行性进行了分析和讨论,最后对进一步的研究工作进行了展望。     

超声背散射信号递归定量分析无损表征CFRP孔隙分布仿真

针对碳纤维增强树脂基复合材料（Carbon fibre reinforced plastics,CFRP）孔隙分布对其力学性能有不可忽略影响的问题,提出对超声背散射信号进行递归定量分析（Recurrence quantification analysis,RQA）的方法来表征CFRP孔隙尺寸和位置分布。建立孔隙直径D范围为26~70 μm的3组含球形孔隙且孔隙位置分布不同的CFRP模型,3组模型的孔隙间距d分别为0.21 mm、0.14 mm和0.09 mm,对模型进行仿真计算,采用RQA方法分析超声背散射信号。研究发现,相同孔隙位置分布时,递归度P_RR（Recurrence rate）随D的增加而减小;相同孔隙尺寸分布时,P_RR随着孔隙间距d减小而增大,d=0.09 mm时模型的P_RR始终明显高于其余两组,D<50 μm时,d=0.14 mm与d=0.21 mm模型P_RR之间差别明显,D ≥ 50 μm时差别较小。结果表明,不同孔隙分布情况下P_RR均存在差异,P_RR可用于CFRP孔隙分布表征。     

分析薄膜厚度与成分的卢瑟福背散射技术

对卢瑟福背散射分析技术的基本原理、试验设备、样品要求及数据处理方法进行了介绍,并举例分析了硅衬底上钛膜厚度的测定,以及钼衬底上钛钼合金膜的实际组分以及氦离子注入杂质的分布范围和实际剂量测定。讨论了卢瑟福背散射技术的发展和应用,介绍了弹性反冲、高能非卢瑟福散射和沟道技术三种分析方法。     

超声与X线胸片在新生儿肺炎早期诊断中的价值对比

目的:对比超声和X线胸片在新生儿肺炎(NP)早期诊断中的价值。方法:回顾分析我院2018年11月-2019年11月接收的疑似NP患儿96例资料,所有患儿均行X线胸片及肺超声检查,对比两种方式检出率,并以临床综合检测结果为标准,对比检查准确率、灵敏度、特异性,并观察超声图像特点。结果:超声与X线胸片检查准确率、灵敏度、特异性等指标均无明显差异(P>0.05);且患儿早期超声图像多以出现B线、胸膜线异常为主要表现,占比分别为100%,78.89%。结论:超声检测在新生儿肺炎早期诊断中具有较高诊断准确性,且应用安全性较高。     

高灵敏管外夹持式超声流量计传感器及流量修正系数的研究

本文描述了一种高灵敏管外夹持式超声流量计传感器，其灵敏度比传统的流量传感器高出５０％，文中对它的安装作了详细论述；通过试验，对该新颖流量计的修正系数作了深入讨论；所推导公式可满足工程需要。作者研制的此种流量计的测量准确度达１％，预计今后将会成为一种主要的流量测量手段。     

基于COMSOL的超声层析成像仿真及图像重建

为了验证三角形和四边形准则的二值逻辑反投影(Binary Logic Back Projection,BLBP)算法在超声层析成像重建过程中的可行性,以超声层析成像的重建区域中同时含有圆柱形和椭圆柱形障碍物为例,利用COMSOL对成像区域内存在障碍物的声场进行仿真,得到声场声压分布。然后,通过提取和处理所获取的声压分布,获得信号矩阵。最后,将信号矩阵代入二值逻辑反投影算法进行图像重建。仿真结果表明:当入射波的波长λ远小于障碍物的尺寸时,声衍射的现象并不明显。重建结果表明:两种准则在几何近似理论下可行,且四边形准则的效果优于三角形准则。     

基于全聚焦算法的骨折超声成像研究

为研究便捷、安全、无电离辐射的骨折检测方法,提出了超声双层折射修正全聚焦算法.首先从信号处理入手,通过回波信号与标准发射信号进行互相关计算,得出噪声含量极低的回波信号.继而利用Filed-Ⅱ裂纹仿真实验验证全聚焦成像对均匀介质检测的可行性,仿真结果显示裂纹宽度平均相对误差为5.60％;最后对离体牛胫骨进行全矩阵数据采集...     

基于企业文化的绩效管理研究

着意于建立以企业文化为基础的绩效管理系统,在论证了文化与绩效的内在逻辑关系之后,将基于文化的绩效管理系统纳入企业的战略框架之下,使新型的绩效管理系统更具效率和整体性、可持续性,变传统的被动式管理模式为员工的自主管理模式.该系统有效地降低了理成本,提高了管理效益.     

Study of iridium/germanium interaction in a lateral diffusion couple

Ion beam analysis using micro-Rutherford backscattering spectrometry has been used to investigate the interaction between germanium and iridium in a lateral diffusion couple. Optical microscopy, scanning electron microscopy and atomic force microscopy have also been employed. When samples of germanium islands on iridium films are annealed within a range of temperatures between 600 to 800 °C, substantial lateral diffusion is observed, resulting in a number of reaction regions. Micro-Rutherford backscattering analysis indicates that the phase Ir₃Ge₇ stretches across the original island interface at all temperatures, with the phase Ir₄Ge₅ forming in the reaction region with unreacted iridium. The phase IrGe₄ is observed to nucleate in the middle of the island at temperatures above 800 °C. Depth information is readily obtainable from micro-Rutherford backscattering spectrometry which is used in conjunction with atomic force microscopy data to estimate the densities of the phases formed. The results demonstrate the complementary nature of the techniques used for studying lateral diffusion couples.     

深度神经网络的语音深度特征提取方法

为了提升连续语音识别系统性能,将深度自编码器神经网络应用于语音信号特征提取。通过堆叠稀疏自编码器组成深度自编码器(Deep Auto-Encoding,DAE),经过预训练和微调两个步骤提取语音信号的本质特征,使用与上下文相关的三音素模型,以音素错误率大小为系统性能的评判标准。仿真结果表明相对于传统梅尔频率倒谱系数(Mel-Frequency Cepstral Coefficient,MFCC)特征以及优化后的MFCC特征,基于深度自编码器提取的深度特征更具优越性。     

Developing new products in a network with efficiency and innovation

When managing a new product development (NPD) problem, a firm needs to consider the cooperation with its strategic partners in a network because surviving independently in the industry is almost impossible. However, due to the large variances among partners in terms of leadership, management, IT infrastructure and organizational cultures, it may lead to poor communication and cooperation and slow responses. A severe impact on the process and outcome of NPD may result. To facilitate buyer–supplier cooperation, suitable knowledge management and product development process management need to be adopted to match the characteristics of the selected NPD mix. In this paper, a supermatrix analytic network process (ANP) model with sensitivity analysis is first developed to select the most appropriate NPD mix. A balanced scorecard (BSC) using ANP with sensitivity analysis is used next to demonstrate the effectiveness of the proposed model in the execution of NPD process.     

超声换能器灵敏度标定的一种新方法-激光超声法

本提出一种利用脉冲激光产生可重复的宽带标准声源,对超声换能器的速度灵敏度进行标定的新方法－激光超声法。简述了激光脉冲产生声脉冲的原理,给出了换能器速度灵敏度的表示方法及标一原理。建立了整套标定装置,并给出了换能器的标定结果。结果表明,该方法可较好地标换能器的速度灵敏度。     

γ-LiAlO2 Single Crystal Grown by Czochralski Technique and Modified by Vapor Transport Equilibration (VTE) Technique

Large-sized (～2 inch, 50.8 mm) γ-LiAlO2 single crystal has been grown by conventional Czochralski (Cz)method, but the crystal has a milky, dendriform center. The samples taken from transparent and milky parts were ground and examined by X-ray diffraction. All diffraction peaks could be indexed in γ-LiAlO2. The crystal quality was characterized by X-ray rocking curve. The full-width at half-maximum (FWHM) values are116.9 and 132.0 arcsec for transparent and milky parts, respectively. The vapor transport equilibrium (VTE)technique was introduced to modify the crystal quality. After 1000℃/48 h, 1100℃/48 h, 1200℃/48 h VTE processes, the FWHM values dropped to 44.2 and 55.2 arcsec for transparent and milky part, respectively.The optical transmission of transparent part was greatly enhanced from 85% to 90%, and transmission of milky part from 75% to 80% in the range of 190～1900 nm at room temperature. When the VTE temperature was raised to 1300℃, the sample cracked and FWHM values of transparent and milky parts were increased to 55.2 and 80.9 arcsec, respectively. By combining Cz technique with VTE technique, large-sized and high quality γ-LiAlO2 crystal can be obtained.     

Manufacture of high sensitive Ag-Fe3O4-PDMS nanocomposite pressure sensor through morphology control of conductive filler

Silver nanowire (AgNW) has been proposed as a promising conductive filler candidate based on its excellent electrical and thermal conductivity properties. However, residual PVP (polyvinylpyrrolidone) exists on the surface of AgNW synthesized through the polyol process. As a result, there is a problem in that the contact resistance (R_C) is increased. This problem can be solved by improving the contact area between AgNWs. Therefore, in this study, the electrical conductivity characteristics of AgNW were to be improved by etching which can increase the contact area of AgNW. The concentration of etchant was adopted as the main parameter, and ideal etching parameter was derived by analyzing the microstructure and electrical conductivity characteristics of the etched AgNW. The etched AgNW showed a minimum resistance of 0.034 kΩ/□, and the etched AgNW showed about 23% improved surface area compared to the as-prepared AgNW. In addition, by controlling the ultrasonic milling parameters, it was intended to produce Fe₃O₄ nanoparticles (Fe₃O₄ NP) that make the conductive structure less dense and prevent stacking between AgNWs by acting as a nano-spacer. The prepared Fe₃O₄ NP showed an average particle size distribution of 150 nm or less. Ag-Fe₃O₄-PDMS (Polydimethylsiloxane) nanocomposite was prepared through such a conductive filler. As a result of analyzing the response characteristics of Ag-Fe₃O₄-PDMS nanocomposite, the resistance decreased linearly as the applied pressure increased, and the root-mean-square was 0.99 or higher.