基于量子阱薄膜的纳机电矢量水听器设计

根据介观压阻效应原理以及柱体声学理论,提出了一种基于量子阱薄膜的纳机电矢量水听器,期望利用量子阱薄膜材料的高灵敏度压阻效应以及水听器精巧的微结构,提高矢量水听器的灵敏度,实现水听器的低频特性及结构微小型化。首先概括地描述了介观压阻效应原理以及柱体声学理论;完成了水听器的结构设计;采用GaAs基微机械加工工艺完成了水听器的加工并对水听器进行了封装,最后对研制出的水听器的性能指标进行了测试,测试结果表明：纳机电矢量水听器不但体积小、质量轻、结构简单,而且能够获取水下声场的质点振动信息,具有＂8字型＂的指向性,可进行水下声信号的定位探测。     

水听器的脉冲互易校准

本文介绍了用在普通水池中进行水听器自由场脉冲互易校准的仪器,该仪器用直流 比较法测量脉冲幅度,并用分差放大器减小示波器光点的误差,因此有较高精度。 文中还介绍了用该仪器进行的声学实验,给出了几种水听器的方向特性,互易关系 正确性的验证以及频率响应。     

一种用于MEMS陀螺仪的隔振平台及其结构设计

为隔离外部环境振动对MEMS陀螺仪性能造成的不利影响,文章设计了一种用于MEMS陀螺仪隔振的单层及双层隔振平台,通过理论分析隔振平台结构参数对隔振性能以及集成隔振平台对MEMS陀螺仪性能的影响,确立隔振平台的设计准则;设计了一种用于MEMS陀螺仪的单层及双层隔振结构及其制备工艺流程,通过ANSYS仿真分析隔振平台结构设计的可靠性及合理性。对1个示例MEMS陀螺仪进行分析,结果表明所设计的单层及双层隔振平台结构合理可靠且均可隔离外界环境振动,通过增大第1层隔振平台质量不仅可以提高隔振效果还可有效降低集成隔振平台对MEMS陀螺仪性能的影响。采用设计的隔振平台结构与工艺流程可实现陀螺仪与隔振平台的圆片级封装,并可采用MEMS的加工工艺大批量生产,降低隔振成本。     

球形障板对矢量水听器接收性能的影响

矢量水听器可以同步共点测量声场空间一点处的声压和质点振速的各个分量,因此其被广泛应用于水声测量、探测、通信等领域。矢量水听器在水声测量的应用中会受到安装载体散射声场的影响,而这种载体可以看作为障板,由于障板的存在使散射声场的分布发生改变,以及矢量水听器的接收性能下降。仅以绝对硬边界为例,对球形障板的散射声场进行了理论计算和仿真分析。并且对带障板条件下矢量水听器的接收指向性的变化进行了仿真研究。结果显示,从散射声场分布图可以直观看出声场发生的变化,矢量水听器的接收性能变化与障板的尺寸、与障板距离远近、声波发射频率等因素有关。     

离子液体型离子聚合物金属复合材料的封装及变形性能

针对水基离子聚合物金属复合材料(IPMC)在空气中性能不稳定且存在松弛变形这一问题,使用离子液体替代水作为IPMC内部溶剂,采用光固化材料对该材料进行表面封装,测试水基IPMC和离子液体型IPMC封装前后的驱动性能,对比水基IPMC和离子液体型IPMC在空气中的长期稳定性能。实验结果表明:在2V电压驱动下,离子液体型IPMC的松弛变形消失,输出力和位移虽有所减小,但该类型IPMC可以承受高的驱动电压;在8 V电压作用下,离子液体型IPMC封装后的材料变形为12mm,输出力达到0.8mN;封装后的离子液体型IPMC的整体质量基本维持不变,驱动性能基本稳定,满足在空气中长期使用的要求。     

ZnO/IDT/SiO2结构声表面波传感器仿真和分析

针对现有声表面波理论模型难以分析多层结构声表面波传感器器件的缺点,利用周期性介质的矩阵本征算子模型,成功对ZnO/IDT/SiO2多层结构中IDT电极的机械特性对装置性能的影响进行了建模。基于此模型,仿真和分析了此结构装置的波传播速度、机械耦合系数等参数与波导层厚度以及电极厚度的关系。并将仿真结果得到的装置传输频率响应与试验结果进行比较,二者基本一致。     

基于氧化铝薄膜的压电水听器的研制

提出了基于AlN压电薄膜结构的单电极水听器,将A1N的压电特性与MEMS微加工技术相结合。采用COMSOL对器件在20~100Hz低频范围内谐振特性进行分析和仿真,得出压电薄膜优化厚度0.8~1.0μm,振动薄膜直径100μm。给出了器件制备工艺流程,采用ICP精准刻蚀A1N薄膜提高成品率,并对实际样品进行高静水压等环境适应性测试。单个水听器阵列结构是40×40,实际尺寸为7×7mm,可以用来制备高性能的水听器集成系统。     

浅海四分量勘探之第四分量检波器的研究

针对用于浅海滩涂地带的浅海四分量石油勘探之第四分量检波器——水听器进行了研究,从传感器网络模型出发,推导了水听器的传递函数,得出了外力与水听器敏感元件应力应变之间的关系,并对水听器建立了振动模型、进行了动态特性分析.设计了水听器的结构,并计算了灵敏度、确定了水听器的参数.对浅海石油水听器进行了性能和灵敏度测试.结果表明,水听器满足浅海勘探的要求.     

一种响应平坦的宽带高灵敏度分布反馈光纤激光水听器

采用聚氨酯材料制作的梭形结构对分布反馈（DFB）光纤激光器进行封装，在驻波管校准声场对其进行测试，由OPD4000相位解调仪精确测量光纤激光水听器的相移量。 通过测试和数据分析，得到1 kHz处DFB光纤激光水听器的相位-声压灵敏度为-122.6 dB re rad/μPa,相当于3.8 nm/MPa； 在10 Hz~10 kHz整个频段内频响曲线非常平坦，波动小于±9 dB,并且信噪比与标准压电水听器相当。     

射频微机电并联电容式开关的参数性能分析

射频微电子机械系统RF MEMS开关的高隔离度与低插入损耗特性,同开关自身的结构参数密切相关。为了得到更好的开关性能,在设计过程中有必要对射频MEMS开关的相关参数进行优化。本文用ADS和HFSS仿真设计软件,对射频MEMS并联电容式开关的微波特性进行了分析和仿真,研究了MEMS开关的等效电路参数和结构参数的变化对RF MEMS开关微波特性的影响。仿真结果表明:等效电容参数和MEMS开关桥宽度是影响开关性能的关键参数,当开关的等效电容参数增加20 pF,或MEMS桥的宽度增加40μm时,RF MEMS开关的插入损耗则可能增加10 dB以上。     

An Index mechanism for multi-scale view in spatial databases

There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

Perspherical Approaches for Electrons in Atoms and Charged Excitons in Quantum Wells

Instead of following Fock’s expansion,we solve the Schrodinger equation for some quantum mechanical manybody systems such as electrons in atoms and charged excitons in quantum wells in a similar way in hyperspherical coordinates by expanding the wave functions into orthonormal complete basis sets of the hyperspherical hannonics(HHs)of hyperangles and generalized Laguerre polynomials(GLPs)of the hyperradius.This leads the equation to     

Advances in broadband wireless communications under high-mobility scenarios

Future mobile communication systems aim at providing very high data transmission rates, even in high-mobility scenarios such as high-speed wheel-track trains, maglev trains, highway vehicles, airplanes, guided missiles or spacecraft. A particularly important commercial application is the strong and increasing worldwide demand for high- speed broadband wireless communications （up to 574.8 km/ h test speeds or 380 km/h commercial speeds） in railways, providing data, voice and video services for applications such as onboard entertainment services to passengers, train control, train dispatch, train sensor status handling and sur- veillance. In such high-mobility scenarios, there are a number of communication challenges, including fast hand- over, location updating, high-speed channel modeling, estimation and equalization, anti-Doppler spreading tech- niques, fast power control, and dedicated network architec- ture. Because signal transmission in very high-speed scenarios will inevitably experience serious deterioration, it is imperative to develop key broadband mobile communi- cation techniques for such high-speed vehicles.     

Wuhan University Journal of Natural Sciences TOTAL CONTENTS

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海南岛地体及其毗邻陆缘晚中生代—新生代古地磁研究和构造演化

本文叙述了对海南岛及其毗邻大陆边缘白垩纪到第四纪地层岩石进行古地磁研究的全部工作过程。通过分析岩石中剩余磁矢量的磁偏角及磁倾角的变化,提出海南岛白垩纪以来经历的构造演化模式如下:早期伴随顺时针旋转而向南迁移,后期伴随逆时针转动并向北运移。联系该地区及邻区的地质、地球物理资料,对海南岛上述的构造地体运动提出以下认识:北部湾内早期有一拉张作用,主要是该作用使湾内地壳显著伸长减薄,形成北部湾盆地。从而导致了海南岛的早期构造运动,而海南岛后期的构造运动则主要是受南海海底扩张的影响。海南地体运动规律的阐明对于了解北部湾油气盆地的形成演化有重要的理论和实际意义。     

Scale-based spatial data model for GIS

Being the primary media of geographical information and the elementary objects manipulated, almost all of maps adopt the layer-based model to represent geographic information in the existent GIS. However, it is difficult to extend the map represented in layer-based model. Furthermore, in Web-Based GIS, It is slow to transmit the spatial data for map viewing. In this paper, for solving the questions above, we have proposed a new method for representing the spatial data. That is scale-based model. In this model we represent maps in three levels: scale-view, block, and spatial object, and organize the maps in a set of map layers, named Scale-View, which associates some given scales.Lastly, a prototype Web-Based GIS using the proposed spatial data representation is described briefly.     

Exciton Seebeck in Molecular Systems

Various applications relevant to the exciton dynamics,such as the organic solar cell,the large-area organic light-emitting diodes and the thermoelectricity,are operating under temperature gradient.The potential abnormal behavior of the exicton dynamics driven by the temperature difference may affect the efficiency and performance of the corresponding devices.In the above situations,the exciton dynamics under temperature difference is mixed with     

Achieving Unusual States of Matter Under High Pressure

The elongation method,originally proposed by Imamura was further developed for many years in our group.As a method towards O(N)with high efficiency and high accuracy for any dimensional systems.This treatment designed for one-dimensional(ID)polymers is now available for three-dimensional(3D)systems,but geometry optimization is now possible only for 1D-systems.As an approach toward post-Hartree-Fock,it was also extended to