水下声传感器网络节点自定位研究

以无线传感器网络（WSN）水下应用为背景,针对水下环境的特殊性,提出了一种基于聚类的分布式无锚点网络节点自定位算法：采用分布式坐标计算,有利于网络节点能量的合理使用;同时,不需位置已知的锚节点,方便了水下环境的应用。仿真论证了影响算法精度的因素,并对比了LAR和MET两种坐标确定方法。对水下WSN应用研究具有重要的参考价值。     

Isolation and characterization of kurstakin and surfactin isoforms produced by Enterobacter cloacae C3 strain

In this work, the extraction, structural analysis, and identification as well as antimicrobial, anti‐adhesive, and antibiofilm activities of lipopeptides produced by Enterobacter cloacae C3 strain were studied. A combination of chromatographic and spectroscopic techniques offers opportunities for a better characterization of the biosurfactant structure. Thin layer chromatography (TLC) and HPLC for amino acid composition determination are used. Efficient spectroscopic techniques have been utilized for investigations on the biochemical structure of biosurfactants, such as Fourier transform infrared (FT‐IR) spectroscopy and mass spectrometry analysis. This is the first work describing the production of different isoforms belonging to kurstakin and surfactin families by E cloacae strain. Three kurstakin homologues differing by the fatty acid chain length from C₁₀ to C₁₂ were detected. The spectrum of lipopeptides belonging to surfactin family contains various isoforms differing by the fatty acid chain length as well as the amino acids at positions four and seven. Lipopeptide C3 extract exhibited important antibacterial activity against Gram‐positive and Gram‐negative bacteria, antifungal activity, and interesting anti‐adhesive and disruptive properties against biofilm formation by human pathogenic bacterial strains: Salmonella typhimurium, Klebsiella pneumoniae, Staphylococcus aureus, Bacillus cereus, and Candida albicans.     

Scaling properties of contact area of pressure-sensitive adhesives

Two new devices were developed to provide accurate measurements of both the contact area and the tack strength of pressure-sensitive adhesives (PSAs). The first one is the "mechano-optical tack tester" (MOTT), which was designed to apply controlled contact pressure by means of a quartz prism probe, for determined contact times, onto the surfaces of PSA samples. The contact area is measured by the reflection of light at the quartz probe surface, which is in contact with the adhesive. The second device is an "acoustic contact tester" (ACT) that measures the tack strength and the contact area between a silicate glass and an adhesive by the reflection of an acoustic wave. Two ultrasonic sensors of different acoustic wavelengths have been built in order to study the scaling effects of the contact kinetics between an adhesive and the probe. MOTT and ACT experiments on a commercial PSA show that the contact area is the main parameter that governs the tack properties of the PSA. The experiments and the modeling point out that the contact area depends on the compression stress, the roughness, the thickness, and the Young's modulus of the PSA. However, comparison of contact kinetics from MOTT and ACT experiments show that the contact area is a subjective parameter that depends on the wavelength of the reflected beam used for its measurement.     

贴片胶涂布工艺技术的研究

贴片胶是SMT生产中重要的辅助材料,它被用来在波峰焊期间将表面贴装元件(Sur-faceMountDevice,简称SMD)固定到电路板的焊接面上。论述了贴片胶的组成、特性、涂布方法、涂布设备、固化工艺及工艺优化问题,重点介绍了在各种工艺下环氧树脂和丙烯酸脂贴片胶的使用方法以及使用中出现的不良与对策,并给出了典型温度曲线以及温度曲线上主要控制点的工艺参数。     

一种并行传输的水声Ad hoc网络多址接入(PTMA)协议

由于存在"隐藏终端"和"暴露终端"的问题,无线Ad hoc网络的应用受到极大的限制.进一步,由于水声信道的特点,例如有用的频率带宽很窄,强时变、多途和长传播时延,使得设计水声Ad hoc网络具有自身特点和难度.本文中,我们为此提出了一种新的多址接入控制(MAC)协议,即并行传输多址接入(PTMA)协议.该协议基于如下思想:为消除冲突而进行多信道预约,这样能在多个信道上并行地传输数据;为缩短等待clear_-to_-send(CTS)的时间,当request_-to_-send(RTS)刚发送完就立即发送分组数据,而不必收到CTS后再发.通过使用OPNET Modeler/Radio仿真器得到的仿真结果显示:PTMA协议能取得较之于适合无线Ad hoc网络的多址接入协议更高的吞吐性能和较低的端到端传播时延.     

Application of Temperature Modulated Relative Dilatometry. Temperatures of adhesion degradation

Application of temperature modulated dilatometry (TM DIL) to investigation on degradation of the adhesion between ceramic films and the substrate is presented. Layers of titanium nitride deposited by plasma assisted physical vapour deposition (PA PVD) methods on the Armco iron substrates were tested. This paper shows that the TM DIL method is helpful in determining the usefulness of the titanium nitride covering of the cutting tools and machine parts. This revised version was published online in July 2006 with corrections to the Cover Date.     

一种新型水声信号发射机的设计与研究

设计并实现了一种体积小、效率高的水声信号发射机,是一些使用电池供电的水声设备(如便携式水声通信设备、便携式水下探测设备等)的关键技术。为满足这些需求,该文从基本理论出发,结合现代音响功放的理论、经验和设计方法,提出了一种全新的微型水声信号发射机设计方案,且通过2007年3月的湖上试验验证了所提出的方案。     

Analysis of the adhesive strength variance in expoxy matrix-boron fiber joints

A new approach to the problem of adhesive joint failure based on the study of the scale effect of the adhesive strength variance is applied to an epoxy matrix-boron fiber system. The shear adhesive strengh is measured using the pull-out technique. It is found that the variance D practically does not depend on the joint area S, whereas the adhesive strength markedly decreases with increase in S. It is noted that the scatter of the values of by far exceeds the experimental errors. The –S and D–S curves obtained behave similarly to the corresponding curves for EDT-10-steel wire joints. The independence of D from S confirms the concept that the failure of fiber-polymer joints in pull-out tests starts near the end of the joint at which the external force is applied. An analysis of the adhesive strength distribution curves within sufficiently narrow (S=0.1 mm²) intervals of S values also confirms this concept.Presented at the 11th International Conference on Mechanics of Composite Materials (Riga, June 11–15, 2000).Semenov Institute of Chemical Physics, Russian Academy of Sciences, Moscow, Russia. Translated from Mekhanika Kompozitnykh Materialov, Vol. 36, No. 4, pp. 435–444, 2000.     

利用激光测量弹性薄板动态响应研究

采用动态全息干涉法,对弹性薄板受水中冲击波作用下的动态响应进行了研究。采用 红宝石双脉冲激光器,实现了动态全息干涉法测量,即两次曝光全息干涉法。设计了反射式动态干涉全息法测量光路,测量了弹性薄板受水中冲击波作用产生的横向变形(弯曲波) ,根据爆炸后不同时间的干涉条纹图,求出了挠度分布图。     

SU-8胶与基底结合特性的实验研究

SU-8胶是一种负性、环氧树脂型、近紫外线光刻胶。它适于制作超厚、高深宽比的MEMS微结构。为电铸造出金属微结构，通常需要采用金属基底。但SU-8胶对金属基底的结合力通常不好，因而限制了其深宽比的提高。从SU-8胶与基底的浸润性、基底表面粗糙度以及基底对近光紫外光的折射特性入手，对SU-8胶与基底的结合力进行分析，首次指出：在近紫外光的折射率高的基底与SU-8胶有很好的结合性。经实验得出经过氧化处理的TI片的SU-8胶的结合性强。这有利于为MEMS提供低成本，高深宽比的金属微结构。