超声编码激励在瞬时弹性成像检测中的应用

瞬时弹性(Transient Elastography,TE)成像广泛应用于肝硬化研究。然而,在临床应用中,对于肥胖病人,该方法很难实现对深度位置的瞬时剪切波进行检测。研究了将超声编码激励应用于瞬时弹性成像剪切波检测的可行性,选用7位巴克码进行编码检测研究。通过剪切波信噪比和检测穿透力两个指标对编码检测与传统短脉冲检测结果进行量化和对比。弹性仿体实验表明,编码检测可以提供比传统短脉冲检测更高的剪切波信噪比和检测深度。离体猪肝实验表明将编码激励应用于组织检测时同样可以实现高信噪比剪切波检测。这些结果表明编码检测应用于瞬时弹性成像检测是可行的,可以增加其检测深度。     

实时超声弹性图像特征量化方法及其应用研究

0引言检测生物组织力学特性的超声弹性成像是近年来新兴的超声影像学技术,但目前的研究工作主要集中在如何构建弹性图像上,缺乏对弹性图像信息与临床诊断结果的前瞻性研究。五分法[1]及弹性比值[2-4]法是最常用的评估乳腺肿瘤方法,受诊断者主观影响较大,没有形成统一的标准,限制了超声弹性成像技术在临床上的广泛应用。构建科学、系统、有效的肿瘤弹性特征的量化和提取方法就显得尤其     

测量生物组织等效杨氏模量的毫米压痕仪

生物组织的弹性是诊断其是否发生病变的重要依据,杨氏模量是反映组织弹性的重要参数。以Labview为软件平台结合数据采集和运动控制等硬件设备,研制了一套测量弹性模量的毫米压痕弹性仪。以市购冷鲜牛肉、猪肉、猪肝和猪肾为试样,测量了球形压头向试样施加的负载力和对应的试样压痕深度,在对测量数据进行校准的基础上,利用基于赫兹接触力学模型的压头半径R、作用力F、压痕深度δ与试样等效杨氏模量E~*间的解析关系,得到各试样的等效杨氏模量。实验结果表明,测得的组织试样等效杨氏模量数值与文献基本相符,所设计的毫米级压痕法测试装置可用于生物组织等效杨氏模量的检测。     

微陀螺动力学建模与非线性分析

建立了微陀螺的动力学模型,采用多尺度方法对微陀螺的非线性模型进行求解,探讨了驱动微弹性梁和检测微弹性梁的非线性刚度对微陀螺输出的影响规律,研究了微陀螺的带宽在非线性刚度作用下的设计原则,结果表明:微陀螺振动系统的检测灵敏度和带宽呈反比关系;微弹性梁的非线性刚度会使得输入角速度与检测输出呈非线性关系。因此,从微弹性梁的设计角度出发,可根据较大的输出或者较小的非线性要求选取合适的驱动微弹性梁;而检测微弹性梁则需要选取较小的非线性刚度。     

CFRP复杂几何结构区相控阵超声检测建模与声传播规律

为厘清碳纤维增强树脂基复合材料(Carbon fiber reinforced plastics,CFRP)复杂几何构件相控阵超声检测中声传播规律,围绕CFRP材料R区开展了弹性特性表征、有限元建模、声场计算及实验验证工作。基于超声液浸背反射法和模拟退火算法求解了CFRP单向板刚度矩阵反问题,并借助Bond变换实现了R区弹性特性的定量描述。结合微观组织分析等获取材料、几何特征,建立了虑及曲面形状、叠层、弹性各向异性的R区相控阵超声检测有限元模型,计算了R区相控阵超声检测A、B扫描信号,发现存在结构噪声和缺陷伪像。在此基础上研究CFRP材料R区瞬态声场并与CFRP平板、弹性各向同性R区和0°单向板R区情况对比,阐明了结构噪声和缺陷伪像的形成机制:弹性各向异性叠层结构导致倾斜入射的超声波发生反射和折射,与沿肋板传播的快速波混叠在R区形成结构噪声,同时多向板R区两侧肋板反射导致缺陷伪像,即材料弹性各向异性与构件曲面叠层结构耦合共同影响缺陷的精准辨识。      

虚拟手术中基于边界元模型的碰撞检测研究

碰撞检测是虚拟手术的关键技术,针对人体组织的材料特性,提出基于线弹性理论的边界元模型。首先对整个场景空间进行剖分,在剖分网格中构建层次包围盒,包围盒相交时再进行精确相交检测。碰撞引起组织形变时,在几何模型的边界上建立线弹性积分方程,碰撞单元区域的形变量能够通过离散的求解结果反映出来。该算法速度快、精度高,很好的解决了虚拟手术系统实时性与真实感之间的矛盾。     

铍青铜淬火及时效的显微组织

铍青铜是优良的弹性合金,其显著特征是在淬火后具有高的塑性,能制成各种形状的弹性元件,经时效后强度、硬度、弹性明显提高,而且弹性滞后小,弹性稳定。本厂显示记录仪表的滚子簧片等仪表弹性元件均采用铍青铜带材制成。仪表弹性元件的弹性性能及其稳定性是影响仪表的显示和记录精度的重要因素之一。由于本厂选择了较合理的淬火以及时效热处理工艺,获得比较理想的淬火组织及时效组织,保证了弹性元件的良好性能。本文分析本厂所用铍青铜带材淬火及元件时效的显微组织,并讨论了显微组织与性能关系。     

一种改进的基于二维自相关的 超声弹性成像方法

超声弹性成像提供组织的硬度信息以区分正常状态和疾病状态.应变图像的质量受到随机噪声的影响,从而降低了病变的可检测性并增加了误诊率.如何有效地抑制噪声,提高应变图像的质量对于诊断是至关重要的.本文提出一种将信号预处理与应变估计及其后处理相结合的超声弹性成像增强方法.将采集的射频(RF)信号经过巴特沃斯滤波来滤除信号中的噪声;通过二维自相关进行组织应变估计;利用统计阈值和中值平滑处理应变估计结果并进一步获得超声弹性图像.为了证明算法的有效性,将本文结果与传统二维自相关方法做对比.实验结果证明,本文方法得到的应变图像信噪比(SNRe)较传统方法提高了0.55 dB,对比度噪声比(CNRe)提高了18.09 dB.因此,该方法可以有效地提高超声弹性成像的质量,有望提高病变组织诊断的正确率.     

基于印压法的软组织模体的杨氏模量测量

研制了基于印压法的软质材料杨氏模量的测量装置,通过有限元仿真方法确定杨氏模量与印压曲线的关系的系数,从而实现对仿组织弹性样本进行杨氏模量量值的标定;用瞬时弹性成像设备对仿组织弹性模体进行测量,其结果与印压法测量结果的一致性,验证了弹性量值传递的可行性。     

轴向拉力对微梁质量传感器精度和热弹性阻尼的影响

针对存在轴向拉力的矩形截面微梁谐振式质量传感器中的质量传感灵敏度、热弹性阻尼以及最小检测质量等问题进行了深入的研究。推导了质量传感器在存在轴向拉力情况下的检测灵敏度、热弹性阻尼以及最小检测质量的表达式。揭示了轴向拉力对质量传感器的工作性能的影响机理。结果表明:轴向拉力会提高质量传感灵敏度;轴向拉力会降低谐振器的热弹性阻尼;轴向拉力可以使得质量传感器捕获更微小的检测质量。     

Effect of Permeable Crystalline Material on Steel Reinforcement Corrosion of Concrete

Permeable crystalline materialcan permeate into pores and cracks of concrete and catalyze the reaction between Ca(OH) 2and unhydrated cement to generate a great quantity needle non-soluble crystals, which can stop up the pores and cracks of concrete, and increase the impermeability of concrete. This paper reported the results of a study conducted to evaluate steel reinforcement corrosion of concrete specimens uncoated and coated with permeable crystalline material as well as mixed with the permeable crystalline material. The properties evaluated for corrosion test were water impermeability, water absorption, compressive strength and potential. The results of water impermeability, water absorption, compressive strength clearly showed that the permeable crystalline material could prohibit water, any soluble salts and moisture from penetrating the concrete to cause corrosion, leaking, and other problems, and it did increase the compressive strength, which was favorable for protection of corrosion of reinforcing steel. Moreover, it was concluded from the potential-time curve that the steel reinforcement of uncoated specimen was in the state of activation whereas that of other specimens coated and mixed with the permeable crystalline material was in the state of inactivation. Above all, it was indicated that the permeable crystalline materialis very effective to protect the steel reinforcement of concrete from corrosion.     

The Research and Application About "Dry Peeling Off" Technology for Airplane Surface Paint Layer

In this paper, the principle of spurting take off lacquer were introduced; and with orthogonal method the unsaturate polyester was prepared ;it was easy to peel airplane paint layer off with this material and equipment.     

Quality Study of Honeycomb Core Shaping Without Wax Stabilization

Sandwich panels utilizing honeycomb cores result in lightweight, high-strength units that are very rigid. Indeed, they give honeycomb panels the best strength-to-weight ratio of any construction type available. Conventionally, the wax is poured into the cell of the core to strengthen the structure and prevent the core from being crushed during milling. Much time and labor is required to wax, mill, and clean the cores. In this study, the process of pouring wax into the core was skipped. In other words, the cutter directly milled the core. Experiments showed that the compressive strength of the core produced without wax stabilization was only 3% lower than that of cores produced using the traditional method. In addition, the drum peel strengths of cores produced without wax stabilization were 38.4% higher than cores produced using the traditional method, in which residual wax seriously polluted the adhesive. It was also found that eliminating the wax process can reduce costs.     

In-process thermal treatment of polylactic acid in fused deposition modelling

Polylactic acid (PLA) is one of the most widely used open source fused filament fabrication materials due to its ease of extrusion, biodegradability, and mechanical strength. The mechanical strength of PLA largely depends on the proper growth of its semi-crystalline structure, which can be severely impaired by a low rate of crystallization, particularly in open source printers. This can be further aggravated by the non-uniform thermal distribution of heat that causes improper curing among the extruded beads of the printing material. As a result, PLA printed on open source printers does not achieve the best mechanical properties. This research, for the first time, proposes an additive-free solution implemented through a detailed set of experimentation to improve the curing rate through in-process temperature variations to cure the joints among the beads. Scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) spectroscopy is used to confirm the improvements in the bead joints. This work is conducted in two phases of experiments. In the first phase, a full factorial ANOVA is used to investigate various process parameters and the important variables are used in the second phase to print test specimens in four different sets.     

Investigation of the Corrosion Behaviors of HVOF-Sprayed Carbide Cernet Coatings in Molten Al-Zn-Si Alloy Bath

In continuous hot-dip galvanization process the corrosion and chemical stability of the sink roll in the galvanizing bath are important problem which effects on the quality and productivity. In order to protect the sink roll the carbide cermet and/or ceramic coatings were deposited on the surface of the sink roll. The WC-, Cr3 C2-cermet coatings were deposited by high velocity oxygen fuel (HVOF) spray, respectively. The coating samples were immersed in molten Zn-alloy containing 50 wt % aluminum at 833 K for 24 hr and 144 hr, respectively. The inter-diffusion and inter-reaction of Zn, Al and elements in coating and corrosion behaviors of these coatings were investigated by XRD, SEM and EPMA etc. The corrosion mechanisms of the carbide cermet coatings and ceramic coatings in molten High Al-Zn-alloy were approached.     

Fundamental study of adhesion of ice to cooling solid surface (Discussion on influence of copper oxide layer on ice adhesion force)

In many situations, ice often adheres to a cooling solid surface, frequently causing serious accidents. It is critical to clarify the mechanism of ice adhesion to the cooling surface in order to prevent ice adhesion. In a past study, the shearing stresses of two kinds of test plates with a copper surface having the higher thermal conductivity were measured. The shearing stress corresponds to ice adhesion force. Both shearing stresses were significantly different; however, the cause remains unclear.Therefore, the present study focuses on an oxide layer as the main factor causing the difference of both shearing stresses; the influence of the oxide layer formed on shearing stress was discussed. And in the removal and reformation processes of the oxide layer, the time variation of the shearing stress was clarified. Moreover, the relationship between the state of the copper surface and the shearing stress was also clarified by surface analysis.     

重塑标准推行格局 推动LED照明的普及（英文）

正When you are enjoying the green,energy-saving and healthy lighting of IKEA LED luminaire,you may not realize that most of IKEA’s LED bulbs are produced by the LED luminaire smart manufacturing system of Hangzhou Zhongwei Photoelectricity CO.,LTD(ZVISION).No longer enclosed in the laboratory,the product standards are brought into the factory workshop and even to the entire production process.Thus,the standards are promoted and applied in a favorable way by enterprises,benefitting consumers with high quality products.     

Chinese Experts Contribute to ISO＇s New Toy Standards

正The international standard,ISO 8124-6,Safety of toys–Part 6:Certain phthalate esters in toys and children’s products,was officially issued by ISO worldwide on August 15.It was the first time for Chinese experts to lead the ISO standard development in toys industry.The standard was drafted by a group of Chinese experts from SAC/TC for toys and relevant Chinese departments and finally completed by a dedicated international group of experts.ISO 8124-6 makes a substantive breakthrough in the aspects of the scope of toys,limitation of plasticizer types,control of test cost,accuracy of test,operation convenience,etc.,offering the operational guidance for toy manufactures and testing laboratories.     

中国质量(北京)大会(英文)

正Themed on"quality,innovation,development",the first China Quality Conference(Beijing)was held in the Great Hall of the People on September 15.Chinese Premier Li Keqiang delivered an important speech at the conference.State Councilor Yang Jing and Wang Yong attended the conference with over 600 domestic and international representatives from foreign,regional and international quality organizations     

National Working Meeting on Land and Resources Standardization

正The National Working Meeting on Land and Resources Standardization was held in Beijing on July 15,2014.Wang Min,the Deputy-Minister of the Ministry of Land and Resources,and Yin Minghan,the Chief-Engineer of SAC addressed the meeting.Representatives from relevant competent departments and technical committees were present.The meeting aims to summarize work,discuss existing problems and make clear working thoughts,promoting standardization work of land and resources to a new level.Wang Min pointed out that the standardization work of land and resources should be centered on the basic principles of"protecting land and resources dutifully,intensively and economically utilizing land and resources,and making all-out efforts to safeguard the public’s rights and interests",highlighted the