厅堂中早期反射声能分布的测量

厅堂中的早期反射声能是决定厅堂音质的重要因素，ＥＤＴ、Ｃ５０、Ｃ６０、响度等音质参量都是由早期反射声能决定的。为探讨早期反射声能在厅堂中的分布及随距离的衰减规律，本文对同济大学的大礼堂（容积为２７０００ｍ２）进行了实测。声源为脉冲电火花发声器，传声器接收到声信号后经１／３倍频程滤波器，采样后得到接收点的脉冲响应，再经积分获得早期反射声能累积值ＲＥＣ（ｔ），其中ｔ是对脉冲响应的积分时间。实验中测量了礼堂中２０个位置上的ＲＥＣ（ｔ）分布及其随接收点到声源距离的衰减率，同时测量了稳态声场声压级在厅内的…     

矩形水池中声能的衰变

本文从波动声学观点出发，分析了矩形水池中声能的衰变，给出一种解算复本征值的新方法，进行了相应的声场测量，测量结果验证了理论计算的正确性。     

热声热机系统的测量与实验研究

对热声热机驱动耗散性负载的性能进行了实验研究和分析,对热声热机系统起振温度和谐振频率进行了测量和标定。得出导致热声发动机工作在二附谐振频率模态下的影响因素。测量和分析了气体充气压力、频率以及谐振管长度对系统驱动制冷机,产生了25℃的温差。     

HEMA在PE膜上辐照接枝物的小角X射线散射研究

用小角Ｘ射线散射（ＳＡＸＳ）法研究了聚甲基烯酸β关羟乙酯（ＨＥＭＡ）在聚乙烯（ＰＥ）膜上辐照接枝物的形态结构。采用Ｔｓｖａｎｋｉｎ模型和Ｂｕｃｈａｎａｎ改进的ＳＡＸＳ分析方法，测定了ＨＥＭＡ／ＰＥ辐照接枝物的长周期，晶片厚度，无定形厚度及－维结晶度等参数。发现ＨＥＭＡ／ＰＥ接枝物存在着两种长周期及两组不同的形态结构参数。笔者提出了“双重夹层结构”模型，对该接枝物的形成机理作了讨论。     

柔性柔水薄壁对波浪的散射

本文假定在微幅波作用下，柔性透水薄壁做微幅摆动，采用线性理论研究了柔性透水薄壁对波浪的散射作用讨论了射波波数，薄壁的摆幅及薄壁距水底的距离对反射系数和透射系数的影响。     

ZnS：Mn^2＋薄膜电致发光器件中电子散射过程的研究

研究了薄膜电致发光器件中的电子散射过程，计算了ＺｎＳ：Ｍｎ＾２＋中声学声子，极化光学声子，电离杂质及谷间散射的几率随电子能量的变化关系，对各种散射这程了比较，发现极化光学声子散射及谷间散射较为重要，杂质散射的重要性取决于浓度的大小。同时研究了它们在不同能谷中的行为，进而研究了温度对散射过程的影响。     

球面波散射因子对光电子全息的影响

用于研究物质结构的光电子全息，其物理机制是光电子波在固体中的散射。在电子能量为５０～２００ｅＶ的中低能量下，不能用通常的平面波近似方法加以研究，必须考虑到光电子波的球面波本质。即使在电子能量大于５００ｅＶ的高能情况下，用平面波近似的方法也应对前向散射进行修正。本文以铜单晶薄膜为例，利用单重散射模型讨论了球面波近似模型下校正因子对光电子全息函数的影响，并与平面波近似作了比较。结果表明，对能量低于２００ｅＶ的光电子全息来说，球面波近似校正因子对前向散射和背向散射的振幅和相位都有较明显的修正。而在高能条件下，球面波近似校正因子主要影响光电子的前向散射，对背向散射的影响较小。进一步研究发现，球面波近似校正可以提高光电子全息的重视图的质量。     

X光电子谱的散射修正

运用Ｗ．Ｓ．Ｍ、Ｗｅｒｎｅｔ等学的理论模型，研究光电子从产生处向固体表面输运过程中弹性散射和非弹性散射对ＸＰＳ谱峰的影响，计算出散射响应函数，并将其应用于Ａｕ和Ｃｕ的ＸＰＳ峰形修正中，用最大熵非负退卷积方法有效地消除散射响应失真，得到光电子在激发处的真实状态和谱峰。     

表面增强拉曼散射在缓蚀剂作用机理研究中的应用

简要介绍了表面增强拉曼散射适于缓蚀剂研究的特点，全面概述了国内外应用表面增强拉曼散射研究缓蚀剂作用机理的情况和发展状况，并对其发展前景加以展望。     

表面速度法在变速箱噪声检测中的应用

基于结构表面振动速度与结构辐射声能的关系，针对以结构声为主的变速箱现场噪声评价问题，提出根据结构表面单点振动速度和工作振型来计算结构辐射声能的方法，此法大大简化了变速箱现场噪声检测的过程，提高了检测效率。通过实验证明这种方法在一定条件下是可行的。     

罗茨转子轮廓的柔性构造及其性能参数的简约公式

为实现罗茨转子轮廓构造及其性能表达方面的通用性和高效率,提出由节圆外、内的任意型式过渡轮廓与任意类型共轭轮廓组成的"柔性"构造方法,由节圆内共轭轮廓上不出现角点干涉的几何条件确定出基础形状系数的取值上限,并以基础形状系数、半叶顶角和叶数为独立变量,由顶点与配对转子节圆内共轭轮廓起点重合的几何关系确定出柔性形状系数,进而由前期研究成果的进一步推导,得出容积利用系数和流量脉动系数的简约公式。结果表明容积利用系数和流量脉动系数公式仅与共轭轮廓的类型及基础、柔性形状系数有关。并得出共轭轮廓类型的影响较小,类型系数统一采用0.05的容积利用系数简约误差小于3%的重要结论。     

微穿孔吸声结构平均吸声特性分析

提出针对微穿孔吸声结构的"平均吸声系数"概念,并通过计算机编程计算分析确定带宽内不同微穿孔结构"平均吸声系数"的变化规律,得到微穿孔结构参数变化时"平均吸声系数"的极值及所对应的微穿孔的结构参数.所提出的微穿孔结构的设计步骤为微穿孔结构的实际应用和设计提供有价值的参考.     

Effects of specularity and particle-particle restitution coefficients on the recirculation characteristics of dispersed gas-particle flows through a sudden expansion

We numerically investigate the effects of restitution and specularity coefficients on the characteristics of dispersed gas-particle flows through a sudden expansion. The studies are carried out using an indigenous finite volume flow solver in a collocated framework with two-fluid model. Parametric studies are performed to gain insights into the differences in recirculation patterns that arise due to variations in restitution and specularity coefficients. The simulations show that particle-particle interactions, quantified by restitution coefficient (e) have a greater impact on recirculation characteristics than particle-wall interactions, which are quantified by specularity coefficient ($?$). Studies reveal that the recirculation lengths tend to decrease as particle collisions become more elastic (as e tends to unity) while they increase, as the value of $?$ increases. However, the changes in recirculation length are very gradual and less pronounced when only particle-wall interactions are considered as compared to particle-particle interactions. From the range of parametric variations studied in this work, the maximum recirculation length has been found when the value of $?$ is maximum and that of e is minimum.     

空盒气压表温度系数的不确定度评定

本文依据JJG 272-2007《空盒气压表和空盒气压计》检定规程的测量方法和JJF 1059. 1-2012《测量不确定度评定与表示》技术规范的要求步骤,分析了各输入量的来源和影响,对空盒气压表温度系数的不确定度进行评定。     

滑动速度对碳纳米管-银-石墨复合材料电磨损性能的影响

采用粉末冶金法制备了碳纳米管-银-石墨复合材料,研究了圆周速度对复合材料摩擦系数、磨损量的影响。结果表明,当压力一定时,随着速度的加快,机械磨损的摩擦系数减小,而电磨损的摩擦系数增大;复合材料的电磨损量远远大于机械磨损的磨损量,电磨损时磨损量在V=10m/s处出现最小值,而机械磨损的磨损量随速度的加快而减小。     

Effects of specularity and particle-particle restitution coefficients on the hydrodynamic behavior of dispersed gas-particle flows through horizontal channels

Specularity coefficient ($?$) and particle–particle restitution coefficient (e) are two important parameters governing the flow physics of dispersed gas-particle flows. In this work, a detailed numerical analysis is carried out to get an insight into the effects of these two parameters in the flow hydrodynamics of dispersed gas-particle flows through horizontal channels. Investigations have also been carried out to find the $?$-e pair for which the phase velocities become an extremum. It has been found that at a particular value of e, both gas and particle velocities at the centerline of the channel increase with increase in the value of $?$, whereas near the wall, they tend to decrease. At a fixed non-zero value of $?$, both gas and particle velocities tend to increase with increase in the value of e. For $?$ equal to zero, which corresponds to free-slip boundary condition for particle velocity, there is no significant variations in gas and particle velocities with changes in e. Out of all combinations of values of $?$ and e investigated herein, it is found that both gas and particle velocities attain a maximum value when both the values of $?$ and e are maximum.     

Studies on the electronic transport properties of some organic semiconductors in thin films

The investigated compounds are some derivatives of orthotolidin-N,N-bis (4-aminobenzene-2-sulphonic) acid. The temperature dependences of the electrical conductivity and Seebeck coefficient are studied on the thin films deposited from dimethylformamide solution onto glass substrates. It is known that the investigated compounds have typical semiconducting properties. The values of some important parameters of the films (thermal activation energy of electrical conduction, concentrations and mobilities of charge carriers) have been determined. The correlations between some of these parameters and molecular structure of the respective compounds are discussed.     

Thermal accommodation coefficient of gases on controlled solid surfaces: Argon-tungsten system

The knowledge of the thermal accommodation coefficient for gases on well-controlled surfaces as a function of temperature is imperative to understanding the mechanism of interphase heat transfer on the microscopic level. With this goal in view, a heat transfer column instrument is designed, fabricated, assembled, and tested for the specific case a argon—tungsten system. With 99.9999%, pure argon, six sets of data are taken in the rarefied gas region in the maximum temperature range of 500–1500 K. Four sets of these measurements are in the temperature-jump region and are analyzed by the constant-power method to compute the thermal accommodation coefficient of argon on a controlled tungsten surface. The other two sets are taken under free-molecular flow conditions and are interpreted in accordance with the man-free-path kinetic theory for the low-pressure regime. These data are compared and discussed in the context of reported data in the literature and interpreted in the light of the surface condition and finish of the tungsten wire.Nomenclature A area of the solid surface - C _j constants in Eq. (3); j=0, 1, 2, 3, and 4 - E _i incident energy flux - E _r reflected energy flux - E _s reflected energy flux when the interaction between the gas and the solid atoms is complete - g temperature-jump distance - L half-length of the metal wire - M molecular weight of the gas - P gas pressure - Q _H total thermal energy conducted by the gas per unit time from the hot surface - Q_KT total thermal energy conducted by the gas per unit time if the striking gas molecules were to attain thermal equilibrium with the hot surface - R molar gas constant - r radial coordinate - r _f radius of the hot wire - S sticking coefficient - S_o initial sticking coefficient - T temperature - T _e linearly extrapolated gas temperature on the hot-wire surface - T _g temperature of the impinging gas molecules - T _H temperature of the hot surface - T _i temperature of the incident gas stream - T _r temperature of the gas molecules receding after collision with the solid surface - T _s temperature of the solid surface Greek Symbols thermal accommodation coefficient for the gas—solid surface - resistivity of the metal wire - gas coverage on the solid surface For an explanation of symbols, see Nomenclature.     

半变系数模型约束PLS估计的渐近正态性

半变系数模型已经获得了广泛的研究和应用,近几年,人们提出许多方法来估计其函数系数和常系数.在PLS方法基础上,本文给出半变系数模型模型在线性随机约束条件下的估计,并证明了常系数和函数系数估计的渐近正态性.     

Mass Transfer Performance of Porous Nickel Manufactured by Lost Carbonate Sintering Process

Open cell porous metals are excellent electrode materials due to their unique electrochemical properties. However, very little research has been conducted to date on the mass transport of porous metals manufactured by the space holder methods, which have distinctive porous structures. This paper measures the mass transfer coefficient of porous nickel manufactured by the Lost Carbonate Sintering process. For porous nickel samples with a porosity of 0.55–0.75 and a pore size of 250–1500 μm measured at an electrolyte flow velocity of 1–12 cm s^?1, the mass transfer coefficient is in the range of 0.0007–0.014 cm s^?1, which is up to seven times higher than that of a solid nickel plate electrode. The mass transfer coefficient increases with pore size but decreases with porosity. The porous nickel has Sherwood numbers considerably higher than the other nickel electrodes reported in the literature, due to its high real surface area and its tortuous porous structure, which promotes turbulent flow.