基于压电效应的人工耳蜗的实验研究

为了提高聋耳的听力, 将压电材料植入到耳蜗内, 利用压电效应直接将声波转化为电信号刺激听神经, 以提高听力. 本研究通过未极化与极化的高灵敏性压电陶瓷的对比, 从体外模拟实验中的声电响应曲线和动物体内植入实验的结果中得到: 未极化的压电陶瓷没有压电响应, 而极化后的压电陶瓷能够将声音信号转化为电信号, 证实了压电陶瓷的压电特性的确可以刺激动物的听神经, 从而降低听阈阈值. 比较了压电陶瓷与压电高分子之间的差异, 结果表明压电高分子也可以刺激听神经来提高听力.     

压电型人工耳蜗的实验研究

系统研究了不同特性的压电陶瓷植入耳蜗及其植入位置对听阈变化的影响，实验结果表明，植入材料的机电耦合系数和电容越大，听阈下降越明显；陶瓷片置于鼓介中内侧贴于螺旋神经表面成功率最高。充分证实了压电陶瓷片植入耳蜗可模拟毛细胞进行声电转换，刺激听神经引起听觉，提高聋耳的呼力这一新构想是成功的。     

人工中耳悬浮式压电振子的优化设计

为了优化人工中耳悬浮式压电振子的植入效果,设计了一种位移放大结构用于改善振子的输出特性。首先采用微CT扫描和逆向成型技术建立了包括外耳道、中耳和简化耳蜗的人耳有限元模型,通过与文献的实验数据比对验证模型的有效性。然后建立人耳与悬浮振子的耦合力学模型,通过有限元的耦合场分析研究加入位移放大结构前后的人工中耳植入效果。研究结果表明,采用位移放大结构后,振子于中高频段的等效声压级得到明显提升,可以有效降低压电振子的功耗。     

聋儿康复中心测听室的噪声控制

供医院门诊和听力研究用的测听室建造量较大,但能符合测听声学要求的则不多.对此,本文概要介绍聋耳康复中心测听室的设计以及建成后的声学测定和评价.供设计和制定有关标准参考.     

陶瓷脊骨垫片强度高、成像清晰

美国Ameclica公司已获美国食品与药物管理局（FDA）批准，可将其A&;#215;&;#215;陶瓷脊骨垫片推向市场。这种陶瓷脊骨垫片强度高、成像清晰、仿生性好，而且与骨骼结合良好。该产品利用公司专有技术MC2工艺制成生物兼容性好的陶瓷脊骨植入件。该产品设计用于脊柱的胸椎-腰椎区植入，用于替换断裂、受伤或稳定性差的椎体。     

悬臂梁压电复合材料振动发电功率与应变的关系研究

设计制备了压电陶瓷片分布植入的玻璃纤维复合材料,建立了悬臂梁振动发电结构模型,计算了悬臂梁模型的应变分布,测试了植入到复合材料不同位置、不同厚度的压电陶瓷片的振动发电功率,研究表明,应变提高2倍,振动发电功率提高4倍以上。     

助听器小常识

助听器是一种电声放大装置,将声音放大并传输到听力损失患者的耳内,从而使听力损失患者得到声音补偿,听到以前听不清、听不到的声音。建起听力障碍者与有声世界的桥梁,助听器无疑是一种好的选择。根据助听器的外形和佩戴位置的不同可分为三种：盒式、耳背式和耳内     

晶体结构对压电陶瓷微位移驱动器特性的影响

对钙钛矿结构的ＰＺＴ－５和钨青铜结构的ＰＢＮＮ二种压电陶瓷制成的压电微位移器进行了电压－位移特性的比较和分析，发现我们所研制的ＰＢＮＮ压电微位移器具有线性好、回零好、等优点。     

振子及其耦合条件对圆窗激励式人工中耳性能影响的数值研究

为研究振子及其耦合条件对圆窗激励式人工中耳植入性能的影响,建立了包括振子和隔膜在内的人耳有限元模型。该模型基于一无任何听力损伤病史的成年志愿者右耳,采用CT扫描和逆向成型技术建立而成,通过与相关文献的实验数据比对验证了模型的可靠性。基于该模型,分析了圆窗上的初始预压力、振子和隔膜的设计参数变化对振子听力性能的影响。结果表明:振子横截面积越大,其对耳蜗的激励效果越差;隔膜的引入有利于提高振子的激振性能,在该研究范围内,较小的隔膜杨氏模量和厚度有利于提升振子的激振性能;振子质量的增加会恶化振子在高频段的植入性能;在圆窗上施加的初始预压力能够提高中高频段上对耳蜗的激振效果。     

高压电性和织构化无铅压电陶瓷的最新研究进展

近年来,性能优异的无铅压电陶瓷因其环境协调性好、污染小而再度成为研究热点.结合近2年来国内外无铅压电陶瓷的研究现状,主要从陶瓷的制备技术方面综述了目前性能最优的BaTiO3和铌酸盐基织构化无铅压电陶瓷的研究进展.重点介绍了制备压电陶瓷的2种新技术,即工程畴形技术(EDC)和局部化学微晶转化法(TMC).针对现今无铅压电陶瓷的种种不足,对今后压电陶瓷的研究方向作了展望.     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

Optimum-Simulation von Ernteprozessen

Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß.     

A study of centrifugal cast high boron high speed steel

In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M₂(B,C), (W,Mo)₂(B,C), M₃(B,C), M₂₃(B,C)₆ type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm². The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K₁ mill housing of bar mill.     

Thixotropy of Systems with Shear Thinning and Plastic Flow Behavior

The definition of the thixotropy is a decrease in viscosity with time in shear and a subsequent recovery of viscosity after the shear deformation is removed.We ...     

Brainstorming for ISO Strategy 2016-2020

正Responding to ISO’s appeal for survey for the to-be-developed ISO Strategy Plan for 2016-2020,SAC hosted a special workshop over the needs and comments of various fi elds on June 8 in Beijing.The workshop was attended by ISO President-elect and Ansteel General Manager Zhang Xiaogang,SAC Vice-Administrator Yu Xinli,and 30 experts from     

CNAS Passes APLAC's PTP Review

正The review group of Asia Pacific Laboratory Accreditation Cooperation(APLAC)carried out a 4-day peer review of the proficiency testing provider(PTP)for China National Accreditation Service for Conformity Assessment(CNAS)from July 28 to 31,2014.CNAS passed the PTP review with excellent performance.Two senior peer reviewers of APLAC made a comprehensive,rigorous and detailed review of CNAS’s PTP accreditation activities,and made the on-spot inspection of the review groups in Shanghai and Shenzhen respectively.