声学标准

19 GBJ 75-84建筑隔声测量规范 本规范为了统一实验室和现场对建筑物和建筑构件的空气声和撞击声隔声测匿,规定了测量方法和测量条件,使所测得的同一建筑物或建筑构件(包括墙、楼板、门和窗等)的隔声性能尽可能地接近,具备相互可比的统一基础,以便于建筑隔声的设计.编制中参考了国际标准ISO 140/1-8-1978 《声学——建筑物和建筑构件的隔声测量》。本规范共分六章为:总则、建筑构件空气声隔声的实验室测量、建筑物内两室之间空气声隔声的观场测量、外墙和外墙构件空气声隔声的现场测量、楼板撞击声隔声的实验室测量和楼板撞击声隔声的现场测量,及七个附录为:名词解释、测     

基于散射矩阵法的飞机壁板声学优化设计

采用散射矩阵法分析夹层板结构声学特性,并对典型的夹层板结构即飞机壁板进行声学优化,预计飞机壁板隔声特性,获得蒙皮、隔声隔热层、内饰板及它们的组合结构的声学性能。针对尾吊飞机客舱后部噪声过大问题,通过增加铺设隔热隔声层以及部分区域优化安装阻尼层等一系列被动降噪处理方法,对主要传递路径的飞机壁板结构进行优化,降低客舱后部噪声水平,并进行试验验证。试验结果表明:散射矩阵法可快速准确获得夹层结构的隔声性能,并与混响室法测试结果吻合较好;在厚度不变的前提下,改变隔热隔声层的铺设方式和材料密度对壁板隔声性能影响较小,但在蒙皮内侧粘贴阻尼层能在一定频段范围提高壁板隔声性能;将优化的壁板构型应用到飞机后舱段侧壁板,舱内噪声水平可降低约3 dB。     

双层加筋板低频声的隔离与有源控制

为探讨加筋对双层结构低频隔声及有源控制的影响,分析了筋条数目及布放位置对双层加筋结构低频隔声性能、有源控制策略选取及有源隔声性能的影响。首先利用模态叠加与声-振耦合理论对双层加筋结构建模,然后采用数值算例对上述问题展开探讨。研究发现,筋条数目增多或筋条靠近基板的中间位置布放,将有利于双层加筋结构低频隔声性能的提高。对于有源控制措施,声控制策略与力控制策略相比,前者的控制效率较高且降噪效果较好。由于筋复杂的耦合影响,添加多条筋或筋条靠基板中间布置时有源控制效果减弱,需施加多个点源才能获得较好的降噪效果。      

实验室隔声测量中试件洞填隙墙传声影响的检验

文章探讨了实验室建筑构件隔声测量中填隙墙传声影响的检验与修正方法。通过实验分析,给出了三种可用于不同隔声量构件的门、窗和玻璃试件隔声测量的填隙墙构造方式。     

水下隔声结构设计及评价方法

为使用混响法快捷地测量水下结构物的辐射噪声,需基于港口或海岸建造海上混响水池。针对内外都是水情况下的海上混响水池壁面隔声问题,设计了一种带梁空气夹层板水下隔声结构,通过仿真比较了不同参数的空气夹层板的隔声性能。为评价声波无规入射情况下水下大尺寸隔声结构隔声性能,提出了一种混响评价方法,通过隔声实验比较了混响法与脉冲法的不同。结果表明：带梁空气夹层板的水下隔声性能优异,声波无规入射情况下,面板厚度0.015 m、空气层厚度0.020 m的带梁空气夹层板在2～10 kHz频段插入损失大于20 dB;混响法可以有效评价大尺寸水下隔声结构的平均隔声性能,其反映的声波无规入射的平均隔声性能更接近于实际应用情况。     

钢结构装配式住宅墙板连接方式对隔声性能的影响*

为提升其隔声性能,通过有限元法数值分析,比较了不同位置墙板的连接方式对房间隔声性能的影响。结果表明：(1)侧墙墙板柔性连接处理对侧向传声的抑制作用显著,当侧墙墙板采用柔性连接后,房间的隔声量在低频段平均可以提升3 dB左右;(2)公共隔墙墙板的柔性连接对房间低频段隔声量提升不明显,甚至在160 Hz、400 Hz、500 Hz等频率下隔声量有所降低。最后,基于模拟分析结果对装配式墙体连接方式提出了改进策略。     

四边简支含多孔材料双层板隔声特性

有限大含多孔材料和空气层复合板结构隔声特性的研究尚不充分。该文旨在研究四边简支边界条件下复合板结构隔声特性。首先基于流体饱和多孔弹性介质的声传播理论计算了声波在多孔介质中的传播波数；继而采用四边简支边界条件下板结构的模态函数，利用模态叠加法和伽辽金法推导了复合板结构隔声系数理论模型，并数值求解复合板隔声量。将理论模型得到的四边简支复合板隔声量与实验结果对比，验证了理论模型的正确性。最后，详细讨论了边界条件、板结构尺寸和多孔材料厚度等主要参数对隔声特性的影响。结果表明：四边简支复合结构隔声特性曲线上“谷值”出现得较少，并且简支复合板隔声特性的第一个“吻合频率”比固支支撑复合板更靠近低频，当频率超过3000 Hz以后，简支和固支边界条件复合板结构隔声特性趋于一致。     

多孔弹性介质三层夹心板的隔声性能研究

应用Biot关于流体饱和多孔弹性介质的声传播理论,采用传递矩阵的分析方法,就复合多孔弹性材料夹心三层板在不同结构情况下的隔声性能进行了理论研究和实验分析,并与同等条件下双层夹心板的隔声性能进行了比较。数值计算和实验结果均表明,与双层夹心板相比,三层夹心板在中高频段隔声性能有明显优势,但低频段隔声性能有一定程度上的下降。研究还表明不同结构的复合三层夹心板在隔声效果上也各有特色。     

基于平面声源的三层有源隔声结构物理机制研究

次级源为平面声源的三层有源隔声结构,深入理解有源隔声的物理机理有助于挖掘降噪潜力及实现系统优化设计。首先对三层有源隔声结构建模并求解系统的振动响应。然后,对控制前三层结构中声能量的传输规律进行深入分析。最后,在辐射板声功率最小条件下,通过分析控制前后声能量传输特性的变化阐述了隔声的物理机理。结果表明,声能量在三层结构中传输形成四个等效的传输通道,中间板与两腔的作用类似带通滤波器,不同的传输通道具有相似的带通特性。有源隔声机理在于,通过控制抑制了通带内的能量传输,显著提高了三层结构整体的隔声性能,从而有效阻止了声波的向后传播。      

局域共振声子晶体复合结构的隔声特性

提出一种四振子对称局域共振声子晶体单元结构,通过改变振子的材料组份,使其在不同频率范围内存在完全带隙以及隔声峰;为拓宽结构隔声的频率范围,通过将不同结构复合的方式,使各结构在不同频率段发挥较好的隔声效果,从而实现隔声范围拓宽;采用有限元法研究了影响复合结构隔声效果的关键因素.结果表明,采用不同结构复合的方法能够有效地拓宽结构的隔声范围.该研究为声子晶体的宽频隔声提供了理论参考.     

Sound reduction in samples of environmentally friendly building materials and their compositions

In order to reduce the negative effect on the environment, environmentally friendly materials are being chosen for the construction of buildings more and more frequently. The building materials that are now used more commonly are clay, straw and reeds. The sound insulation properties of these environmentally friendly materials have not yet been examined thoroughly. This paper presents most commonly used sound reduction indexes R_W that have been measured in the semi-anechoic chamber and determined during the simulation. It has been found that adobe, pressed straw and reeds (oriented parallel to the sound transmission) are suitable for low-frequency sound insulation. The material with the best sound reduction index was adobe. The sound reduction index R_W of a 200 mm thick adobe wall reached up to 43 dB.     

Fluorometric Characteristics of a Wave‐Guide Cell with Low Refractive Index

Recently, Teflon AF2400 (AF 1600, and AF 1601) was commercialized (DuPont Fluoroproducts, Wilmington, DE, U.S.A), that has a refractive index (1.29) lower than water (1.33), and which means that the wave‐guiding of light is possible in water. In this study, we used Teflon AF 2400 as a waveguide capillary longpath cell for fluorometry. He‐Cd and Ar⁺ lasers were used as the excitation source, at 325 nm and 514.5 nm respectively. The length of the capillary wave‐guide cell was 18.70 cm. The was wound twice on a flat surface (loop diameters: 2 cm and 3 cm). The excitation was executed through the wave‐guide cell and the fluorescence from the wound capillary cell wall was collected in a perpendicular direction to the loop. With excitation at 325 nm, the fluorescence intensity at 450 nm emitted from the cell wall decreased along with the increase in the refractive index of the solvent. This can be caused by attenuation of the source light due to absorption by the solvent. In our experiment, the solvent of higher refractive index has the higher absorption at 325 nm. On the other hand, the fluorescence intensity at 590 nm, with excitation at 514.5 nm, increases with increased refractive index of the solvent. This result shows that an increase in the refractive index of the solvent is preferable for maintaining the wave‐guiding of the source light. Here, the characteristics of fluorescence spectrometry are discussed in terms of the collection of fluorescence from the wave‐guide capillary cell wall.     

Development of multiple drywall with high sound insulation performance

Experimental studies for the development of multiple drywalls with a high sound insulation performance are performed. Firstly, a means of preventing the sound insulation deterioration due to the coincidence effect at high frequencies is investigated by layering two plasterboards with different physical characteristics. Based on the results, a double drywall with a sound insulation performance of R_w = 61 is developed. Further more, a double drywall of R_w = 64 , a triple drywall of R_w = 86 and a quadruple drywall of R_w = 90 are developed.     

Improvement of color-rendering characteristics of white light emitting diodes by using red quantum dot films

Red quantum dot (QD) films were applied to a conventional white light-emitting-diodes (LEDs) module consisting of 72 LEDs for improving color-rendering properties. Total three QD films with different QD concentrations, two diffuser plates, and six optical configurations were combined and investigated to find an optimized optical structure. QD films formed a red peak near 630 nm in the spectrum which significantly increased the overall color rendering index (CRI). The lateral optical cavity formed by a vertical QD wall and the vertical cavity formed by the diffuser plate and the reflection film in the lighting module played an important role in the improvement of the color-rendering properties. Especially, the adoption of the lateral optical cavity formed by the QD wall was an effective way to improve both efficiency and color rendering properties of the LED lighting. The present result suggests a new possibility of designing high-CRI LED light sources whose color properties can be tuned easily by simply applying and relocating QD components in conventional LED lightings.     

具有蜂窝内壁的遮光罩杂散光抑制特性分析

将具有蜂窝内壁结构的遮光罩内的杂散光传播分解为蜂窝结构的散射、内壁等效面传播两个层次的行为。通过建立蜂窝结构的等效面各向异性反射模型,采用蒙特卡罗法模拟获得内壁等效面的双向反射分布函数(BRDF)。以此为基础,再次采用蒙特卡罗法模拟遮光罩内壁等效面的杂散光传播过程,分析了该类遮光罩的杂散光抑制特性,并讨论了蜂窝高度和涂层反射率的影响。结果表明,遮光罩内壁蜂窝结构有很好的杂散光抑制作用;蜂窝高度与边长之比δ≥1时,遮光罩的抑制能力不再变化,降低涂层反射率能够有效地增强抑制效果。     

Sound modes in a nonequilibrium fluid with acoustic boundary conditions

The sound modes in a plane fluid layer with sound-absorbing walls at different temperatures are evaluated. The eigenvalue problem is solved by means of a singular perturbation theory and the WKB method. The bending of sound, the nonexponential damping, and the roie of the wall admittance are discussed.     

Comments on ‘Absorption mechanisms for waterborne sound in Alberich anechoic layers’

The vibrational behaviour of Alberich-type absorbers is reviewed once more. Two types of resonance mechanisms are known to be present in such layered configurations. One is due to the radial motion of the hole wall and the other to the drum-like oscillations of the cover layer. The relative importance of these two mechanisms is discussed, and criticisms of an earlier paper of the author are answered, and are placed in proper perspective.     

凹腔非定常特性的数值模拟

采用基于Menter SST两方程湍流模型的DES方法,数值模拟开式凹腔在跨声速条件下的非定常流动特性.计算凹腔底部和后壁面上的点的声压级频谱以及总声压级,证明在第二噪声模态上的声压级最大.     

Acoustic and thermal field investigation of low-cost dwellings, a case study in Brazil

The present paper presents acoustic and thermal performance evaluations carried out in low-cost houses located at the Vila Tecnológica de Curitiba (Technological Village of Curitiba), in Curitiba, Brazil. Two dwellings were evaluated, which were built according to different building systems: (1) the building system Batistella, built with pre-fabricated modules and elements, composed of reforestation wood and (2) the building system Constroyer, composed of expanded polystyrene (EPS) plates, framed in a welded iron mesh, with structural plastering. For the thermal performance evaluation, it was verified that the materials used in the envelope were quite significant for controlling heat gains and losses through the building elements as well as for regulating heat storage. In this case, the system with highest thermal inertia presented better results. Results showed that both building systems had poor acoustic performance, characterized by a low weighted apparent sound reduction index of the façade dB. The German DIN 4109 Norm recommends a minimum of dB. The weighted apparent sound reduction index measured for internal walls was dB and dB, for the building systems Battistela and Constroyer, respectively. The minimum required by German regulation VDI 4100 is dB, for internal walls.