客观声学参数实验测量的讨论

根据对一个音乐厅的脉冲响应实测数据,分别从房间脉冲响应和双耳房间脉冲响应计算客观声学参数,然后分析比较了两种脉冲响应条件下的这些参数.结果表明,由于包含了人头及双耳对声波的作用,严格说来,双耳房间脉冲响应计算的客观声学参数与房间脉冲响应计算的客观声学参数有显著性差别.另外,从其中4个参数的相关性检验来看,在双耳房间脉冲响应条件下参数之间的相互独立性更为明显,这同日本声学家安藤四一通过主观优选实验得到的声学结论较为一致.鉴于厅堂的音质主观评价是一项由听音人参与的听觉行为,文中最后指出,由双耳房间脉冲响应去计算各项客观声学参数对指导厅堂的音质设计实践会更有实际意义.     

谈娱乐空间（KTV）声学设计分析与发展

阐述了KTV的起源与发展,并从房间的混响、声音的扩散、房间的隔音、包间的家具和装饰等多个方面对KTV室内声学设计的方法进行了探讨以提高KTV室内声学设计水平,从而创造好的声场环境,使好的音响设备发出,美妙动人的音乐。     

室内粗糙表面声散射体掠入射角度散射估计

针对经典边界元方法对掠入射角度下的散射估计精度较低的问题,发展了一种边界无网格模型.此模型将散射体视为具有无限延伸的形式,避免了经典边界元法中薄板形式所导致的声压差问题,而且更加符合实际房间中散射体的存在形式;模型利用无网格算法实现数值仿真,可对任意表面形状特别是曲面散射体具有更高的仿真精度。利用边界无网格模型计算了不同形状散射体的散射系数及散射声场,并将结果与解析方法、测量实验进行了对比.对比结果表明,边界无网格模型可以准确预测散射体的散射性质,特别是对掠入射角度的估计要优于经典边界元法.研究结论可应用于室内声学散射体特征预测及优化设计,对提高声场扩散及室内音质水平具有重要意义.     

声学小房间的比例及形状研究

声学小房间低频声场的不均匀一直是困扰着建筑声学设计的问题。本文利用有限元模型模拟的方法对不同比例和形状的声学小房间进行声场分析，在20Hz到200Hz的频率范围内，得到房间的频率响应曲线。首先，通过对以往文献中较好比例的矩形房间进行模拟分析，得出矩形声学小房间的较好比例。然后，变换房间的形状进行声场分析，与矩形房间作比较，探计声学小房间的适合形状。确定精确的房间形状标准是不可能的，所以本文通过模拟空间得出一种简单的房间比例标准，以确定大部分的空间是好的，这对录音室、听音室、声学测量用房等声学小房间设计中尺度和形状的把握是十分有意义的。     

广州白云国际会议中心世纪大会堂声学设计综述

对广州白云国际会议中心D幢2600座世纪大会堂的建筑声学设计做了相关的综述,着重介绍了大会堂观众厅的形体调整、室内声学设计、建筑机电设备的噪声与振动控制等内容。室内声学设计过程中,利用室内声学计算机模拟分析这一辅助设计工具,对大会堂观众厅的声场特性及其对应各项音质的物理参量进行了模拟分析计算,对声学初步设计所提出的音质设计方案进行了论证,为厅内的室内声学设计提供了优化和调整的依据。文中对完工后的声学测试结果和使用后的主观音质效果也进行了阐述。     

膜结构高大空间音质设计浅析——以西亚斯国际学院体育馆声学改造为例

膜结构顶棚在高大空间中的广泛使用对大空间音质设计提出新的挑战.该文阐述了膜结构对室内声环境产生的不利影响,并以膜结构体育馆声学改造为例,通过声学测量和主观试听的方式确定症结所在,并针对该体育馆存在的不良频率特性、聚焦、颤动回声等声学缺陷提出了相应的解决方案.为了验证改造效果,采用计算机模拟仿真预测室内声场,并在竣工后进...     

教室声学设计分析

对两种不同类型教室的房间比例、混响时间、频率响应、本底噪声等建声参量分别进行了实际测量和计算.利用有限元模型模拟的方法给出了部分声场分析.比较了两教室设计中出现的问题并进行了讨论进而明确了教室声学设计的基本要素,为教学用房的建筑设计提供了较为合理的参考.     

小型录音室声学设计

主要介绍了小型录音室的音质要求及声学设计方法,根据小空间中声场特点着重对混响时间的频率特性及声扩散等声学要求进行了设计,为满足录音对信噪比的要求,设计中采用了综合降噪措施,降低室内背景噪声,通过验收测试数据及使用人员评价,说明各项声学指标满足声学要求及使用要求。     

基于仿真脉冲响应的厅堂音质评价

为进行可听化技术及厅堂音质评价研究,对黄埔青少年宫剧院进行了脉冲响应及其声学参数测试,同时应用ODEON软件对该剧院进行声场仿真,并将计算机仿真和实测结果相比较,通过主观听音试验,探讨应用仿真脉冲响应进行厅堂音质评价的可行性,为进一步实现厅堂音质可听化评价奠定基础。     

一种能量守恒的双向耦合简正波水声传播模型

针对非水平边界条件近似处理所引起的双向声场能量不守恒问题,提出了一种满足能量守恒的双向耦合简正波模型。在模型的建立中,严格考虑了非水平界面的边界条件,并依据介质运动方程和连续性方程推导了便于数值计算的耦合微分方程。同时,结合能量守恒方程和不同海底参数下的数值计算,对模型的准确性进行了研究。由理论分析和仿真结果可以看出,边界条件的严格考虑将导致边界修正项的产生,而边界修正项的引入确保了耦合系数满足对称性和模型所计算的声场满足能量守恒,使得本模型可充分考虑边界水平变化对声场的影响,实现非水平分层波导中双向场的准确计算。     

板类结构的阻抗建模方法研究

介绍了二维阻抗方法以及机电耦合有限元方法的基本原理,使用2种方法计算了铝板在PZT驱动元件作用下的阻抗反应,获得了结构的机电阻抗.对2种方法的计算结果进行了对比分析,发现两者在低频段吻合较好,在高频段稍有差异,但是整体上趋于一致.     

青马悬索桥的时域模态识别

文章研究了青马悬索桥模态参数时域识别.青马桥脉动测试信号弱、干扰因素多,模拟滤波器的滤波效果又不好,而Chebyshev数字滤波器却能精确地确定通带和阻带的边缘频率,故本文采用它对脉动加速度进行预处理.然后用RD函数将脉动信号转变为自由衰减信号.为了提高时域法模态参数识别精度,本文采用了改进的特征系统实现算法.由于青马桥加劲梁长达2160m,加速度计和仪器通道数有限、测试只能分组在不同时间进行,而目前的时域模态技术只能处理同时记录的数据.本文先分组时域识别、然后通过参考点拼装全桥的模态,共识别出青马桥的79个模态,包括五个复模态.后者与青马桥典型复阻尼特性相一致.本文还把上述结果与频域法及有限元计算结果进行了比较.     

Long-term performance analysis of chemical filters in clean rooms based on a prediction model

Chemical filters are the most important devices for removing gas-phase pollutants in clean rooms. However, the testing concentration of chemical filters is too high for reflecting their performance in a real clean room environment. This study tested the adsorption performance of chemical filters in the two most commonly used shapes at different concentrations. Then, the Langmuir equation and Wheeler-Jonas kinetic equation were combined to establish an adsorption performance prediction model of chemical filters under actual conditions. The predicted values of the model were in good agreement with the experimental results, which indicated the high accuracy of the prediction model. The model does not need to test the microscopic parameters of the adsorbent and can maintain high accuracy at low concentrations. A fast method for calculating the service life of chemical filters was also presented. Based on this model, the total cost of using a chemical filter with a high carbon content in microelectronic clean rooms could be decreased by 45% due to decreasing the number of filter replacements over 3 months. So a chemical filter with a high carbon content should be preferred over a filter with low resistance in microelectronic clean rooms.     

SSI效应对隔震结构的地震响应及损伤影响分析

基于弹性地基梁理论和波动理论计算群桩-土地基对上部结构的动力阻抗,进而研究桩土-结构动力相互作用对高层隔震结构地震响应及非线性损伤的影响。首先计算桩周地基水平刚度系数,采用改良的Penzien模型将群桩等效为单桩,考虑一定桩长范围计算桩头的水平刚度,同时根据结构振动频率与地基基本频率的大小关系,考虑地基材料阻尼和辐射阻尼的影响。以某高层隔震工程为例,根据实际桩布置及土层分布情况计算地基阻抗,利用等效线性化模型对结构进行反应谱分析,计算结构隔震前后SSI效应对其动力响应的影响,再利用三维非线性损伤模型分析SSI效应对结构主要构件损伤的影响。计算结果表明,随着结构层数的增加,SSI效应的影响减小,考虑SSI效应会使隔震层位移和隔震支座面压利用率提高,而对隔震层上部结构的层间位移基本没有影响;考虑SSI效应后结构连梁的损伤减小,而框架柱和剪力墙这些竖向构件损伤增加;长周期地震动作用下结构的SSI效应更显著。     

Numerical investigation into the stiffness anisotropy of asphalt concrete from a microstructural perspective

A micromechanical model was built in this paper to investigate the stiffness anisotropy of asphalt concrete (AC) using the discrete element method. Four three-dimensional cubic AC digital samples with different aggregate particle orientations were built using discrete element software PFC3D. The aggregate gradation and shape, air voids and mastic included in the digital samples were modeled using different contact models, with due consideration of the volumetric fractions of the different phases. Laboratory uniaxial complex modulus test and indirect tensile strength test were conducted to obtain material input parameters for numerical modeling. Simulation of the uniaxial cyclic compressive tests was performed on the four cubic samples loaded in three different directions. Dynamic stiffness in different directions was calculated from the compression stress–strain responses. Results show that the AC stiffness is significantly dependent on preferential orientation of aggregate particles. The AC stiffness in the long-axis direction of aggregate particles is shown to be up to 43% higher than the stiffness in the particle short-axis direction. The stiffness anisotropy of AC decreases as the mixture temperature drops.     

饱和土中大直径缺陷桩水平振动响应研究

为了研究成层饱和土中存在缺陷的大直径灌注桩的水平振动响应问题,基于Boit理论和严格的平面应变假设建立缺陷桩-饱和土横向耦合振动简化模型。引入势函数并利用算子分解法、分离变量法得到桩周饱和土对桩的水平作用力,再利用桩土接触面耦合条件及刚度矩阵传递法得到桩顶复阻抗;最后,通过模型对比与退化对比验证本文解的合理性。研究结果表明:(1)扩径对提高桩顶复阻抗起到的作用相对较小,但是缩径的出现将明显降低桩顶复阻抗;(2)桩顶动刚度和动阻尼对桩身缺陷大小和长度的敏感度不同,动刚度较动阻尼更为敏感;(3)桩顶附近缩径缺陷会导致桩顶复阻抗显著降低,而桩中部和端部附近缩径缺陷对桩顶复阻抗的影响相对较小。     

On subsurface box-shaped lined tunnel under incident SH-wave propagation

In this paper, a half-plane time-domain boundary element method is applied to obtain the seismic ground response, including a subsurface box-shaped lined tunnel deployed in a linear homogenous elastic medium exposed to obliquely incident SH-waves. Only the boundary around the tunnel is required to be discretized. To prepare an appropriate model by quadratic elements, a double-node procedure is used to receive dual boundary fields at corners as well as change the direction of the normal vector. After encoding the method in a previously confirmed computer program, a numerical study is carried out to sensitize some effective parameters, including frequency content and incident wave angle for obtaining a surface response. The depth and impedance ratio of the lining are assumed to be unvaried. The responses are illustrated in the time and frequency domains as two/three-dimensional graphs. The results showed that subsurface openings with sharp corners distorted the propagation path of the anti-plane waves to achieve the critical states on the ground surface. The present approach can be proposed to civil engineers for preparing simple underground box-shaped models with angular boundaries.     

一种用于计算雷击接地网时最小冲击接地阻抗值的方法

为了研究接地网在雷击时冲击接地阻抗的特性,提出了一种型等值电路,在考虑火花效应的条件下,运用ATP-EMTP仿真软件对接地网进行分析计算。将土壤电阻率以内分为四个区间,每个区间对应一个地网有效面积值。并运用多项式回归分析软件得出相应区间的冲击接地阻抗拟合公式,能方便计算不同条件下冲击接地阻抗的最小值。为防雷接地工程计算提供参考依据。     

Effect of variable ventilation timing on the estimated temperature of an enclosure

This paper discusses how indoor air temperature is controlled by adjusting ventilation rates and timing. The test enclosure was assumed cube of 3 m side with a facade of 50% glazed and five massive internal walls. The 11-element thermal model is used to describe the complex pattern of heat exchanges which take place within an enclosure.

The boundary value problem is solved numerically. The finite difference method is used to estimate the temperature response of the enclosure due to steadily maintained outdoor air temperature which repeats itself day by day. The solution was carried out on a digital computer to give the indoor air temperature as well as for the room surfaces. Ventilation rates, from 0 to 100 ACH (air change/h) were assumed for the different ventilation timings.     

Two-layer zone model including entrainment into the horizontally spreading smoke under the ceiling for application to fires in large area rooms

A model for smoke filling in a large room was developed that considers entrainment into the horizontally spreading smoke under the ceiling. This was accomplished by incorporating a simple model for the spreading ceiling jet into the two-layer zone model. Here, the proposed model was validated by focusing on the horizontal smoke spread phase on the basis of the previous experimental data of smoke spread in a large office room. The calculated results were in good agreement with the experimental data. In addition, a case study on the smoke filling in a large room was conducted to clarify the characteristics of the proposed model. As a result, the proposed model can predict the underside of the smoke layer to be lower than the two-layer zone model.