双喷嘴乳粒发生器的研制及初步应用

 叙述了双喷嘴乳粒发生器的工作原理、设计关键点及设计思路,利用该发生器开展了双层乳粒的制备实验研究工作。研制的双喷嘴乳粒发生器在喷嘴处的3层管的位置能够通过简单调节达到同心,使得双层乳粒包覆的可靠性得到提高。研究了制备的乳粒的分散性和稳定性,并分析了形成双层乳粒的油相和水相的流速比,结果证明：利用所研制的双喷嘴乳粒发生器可以容易地制备出单分散性双层乳粒,油相与水相的流速比为0.3~15.0时,可形成双层乳粒。     

基于超声波干涉的峰谷法计算声速值及实验误差探讨

介绍了基于Cassy Lab软件下的超声波干涉实验,提出了利用超声波干涉现象测量声速的方法.根据干涉理论推导了峰谷法测量声速的计算公式.分析和探讨了峰谷法计算声速的误差来源和改进方法.     

应用声发射技术的钢筋与混凝土粘结滑移特性研究

为研究钢筋与混凝土间的粘结滑移特性,分别对不同粘结长度的钢筋混凝土试件进行了拉拔试验,同时对粘结长度相同而钢筋外形不同的试件进行了比较试验.利用声发射技术采集相应波形信号,并对采集信号进行了小波去噪和Gabor小波时频分析.结果显示,各试件受力全过程均可分为完全粘结、局部脱粘、非线性滑移及残余粘结四个阶段;不同粘结长度...     

Some applications of Banach algebra techniques

We consider some functional Banach algebras with multiplications as the usual convolution product * and the so‐called Duhamel product ?. We study the structure of generators of the Banach algebras (C⁽ⁿ⁾[0, 1], *) and (C⁽ⁿ⁾[0, 1], ?). We also use the Banach algebra techniques in the calculation of spectral multiplicities and extended eigenvectors of some operators. Moreover, we give in terms of extended eigenvectors a new characterization of a special class of composition operators acting in the Lebesgue space L^p[0, 1] by the formula (C_φf)(x) = f(φ(x)).     

Experimental assessment of a multicarrier underwater acoustic communication system

This paper presents a multicarrier communication system which transmits information on independent subcarriers to achieve an increased data rate. For this system, a passive-phase conjugation (PPC) based receiver structure is assessed by processing data collected in sea trials. Based on temporal diversity (pulse compression) exploited by PPC processing, an adaptive multichannel decision feedback equalizer is used to remove intersymbol interference, where spatial diversity is exploited by adaptive multichannel combination. The digital phase-locked loop (DPLL) technique is implemented for carrier-phase tracking. In the scenario of low input signal-to-noise ratios (SNRs), the receiver structure achieved superior performance using a common DPLL. In a depth-fluctuated environment, two sea experiments were conducted over ranges of 2 km and 4 km, respectively, and this communication system was assessed with a data rate of 4 kbps. In terms of mean square error, output SNR and bit error rate, this receiver structure has demonstrated its performance for the multicarrier communication system.     

Potential solutions to improved sound performance of volume based lightweight multi-storey timber buildings

Lightweight building systems in general suffer from poor sound insulation, especially in the low frequency region. Since no reliable mathematical models that can predict the impact sound pressure level exists, the lightweight building design is to a high extent based upon previous experience and upon measurements. A special difficulty is related to experimental measurements since the variation among identical units must not be neglected. A modern volume based lightweight wooden building concept has here been tested by numerous well controlled measurements, in laboratory as well as in more field like conditions. The volume construction technique offers new possibilities and challenges to improve sound insulation in light weight timber construction. The main purpose was to investigate how different constructional solutions in the floor, like plaster board, mineral wool, elastic glue, dividing board, floating floor etc., affect the sound insulation. Many of the tested modifications resulted in only marginally changed impact sound pressure level but parameters that substantially can improve the sound insulation were found in using elastic glue to mount the floor boards, to install extra board layers and to use floating floors.     

用各向同性材料实现宽带声波功能器件设计

利用坐标变换的方法并结合保角映射技术,论文介绍了一种利用常规的各向同性材料来设计声波器件的方法.基于此理论,设计了二维声波隐身斗篷,并进行有限元模拟,证明了该器件的有效性.另外由于设计中没有利用材料共振的性质,所以器件是宽带有效的.该方法将有助于拓宽声波功能器件的设计,并为实验验证声波器件提供了可能.     

Exploring human rhythmic gait movement in the role of cerebral cortex signal

The rhythmic movement is a spontaneous behavior due to the central pattern generator(CPG).At present,the CPG model only shows the spontaneous behavior,butdoes not refer to the instruction regulation role of the cerebral cortex.In this paper,a modified model based on the Matsuoka neural oscillator theory is presented to better show the regulation role of the cerebral cortex signal to the CPG neuronal network.The complex interaction between the in put signal and other parameters in the CPG networkis establish...     

等离子喷涂铁基涂层的疲劳磨损裂纹行为

采用等离子喷涂制备了铁基涂层,使用球盘式疲劳磨损试验机进行涂层的疲劳磨损试验,利用声发射技术在线判断涂层开裂,并通用透射电子显微镜（TEM）分析了试验前后涂层内部微观结构,研究了喷涂层疲劳磨损裂纹的扩展行为。结果表明：制备的涂层致密,结合状态良好,主要相为铁素体,同时存在大量的非晶-纳米晶相,利用声发射技术能够表征涂层的临界失效状态,其内部疲劳磨损裂纹主要以韧性穿晶断裂的形式扩展。