共查询到20条相似文献，搜索用时 93 毫秒
1.
调研了住宅建筑楼板构造,选取不同构造类型楼板进行测试,结合?民用建筑隔声设计规范?现行标准和征求意见稿分析对比。结果表明,大部分常见的毛坯状态混凝土楼板构造仅能满足现行国家标准要求的低限值;同种楼板构造住宅建筑中客厅的计权撞击声压级低于卧室;瓷砖楼板仅能满足现行国家标准要求的低限值,木地板可以满足修订后新标准的低限值要求,采用浮筑楼板构造的木地板面层可以满足修订后新标准的高限值要求。 相似文献
2.
In this paper, three different modeling ranges were selected in the structural analysis for a hydropower house. The analysis
was carried out using ABAQUS 6.6. The modeling range has a remarkable effect on finite element method (FEM) calculation result
at the middle position of typical cross-sections where the concrete is relatively thin, and at the region close to turbine
floor. If the ventilation barrel, floor slabs and columns above turbine floor are excluded from FEM model, the maximum rise
difference of pedestal structure increases by about 24% compared with that of the whole model. It is indicated that different
modeling ranges indeed affect FEM calculation result, and the structure above turbine floor in the FEM model should be included. 相似文献
3.
甘圣丰 《淮南职业技术学院学报》2004,4(1):1-3
分析了刘桥一矿Ⅱ62采区煤层底板突水原因，介绍了突水后的治理方案及注浆工艺；重点说明如何预防未开采区突水的方法：一边采取注浆加固煤层底板构造薄弱带，增大煤层底板有效隔水层厚度；一边将可能引起突水的高压水源用近位疏放的办法降低水压值，确保回采时突水系数比临界值低，从而达到安全回采的目的；对在同类地质条件下安全采煤具有一定的参考价值。 相似文献
4.
杜海军 《十堰职业技术学院学报》2007,20(5):92-93
分析了某生产线车间噪声分布特性及操作室和配电室之间通风的要求,设计了合理的送、排风系统,并对操作室进行隔声降噪综合治理,使操作室内距观察窗0.5 m处A声级噪声由84 dB(A)降至68.2 dB(A)。 相似文献
5.
研究了利用分布式点力源作为次级力源对封闭空腔内的结构辐射噪声进行控制的问题,并对封闭空腔中结构辐射噪声的控制机制进行了分析.建立了包含2块简支弹性板的矩形封闭空腔,并将其作为研究对象.通过对初、次级声场以及结构-声耦合的特性分析,以减小腔内声场的声压级为最优控制目标,分析比较了在不同位置及参数的次级点力激励下腔内声场的声压级响应.仿真结果表明,在2块弹性板上施加联合激振力控制腔内噪声的效果要明显好于激振力只作用在受激弹性板上. 相似文献
6.
李健 《南宁师范高等专科学校学报》2010,(5):102-104
有限元法已成为工程分析中强有力的数值分析工具。根据有限元理论与技术发展的特点,针对传统有限元课程教学体系中存在的数学、力学理论起点高,学生难于掌握等问题,对建立课程新的内容体系,通用有限元软件应用和与实际工程问题的教学内容、方法以及课程安排进行改革。实践证明,通过教学改革,对学生理论基础与实际操作能力的提高起到了积极的作用。 相似文献
7.
According to the structural characteristics of hazardous waste landfill,a new model based on the finite element method(FEM)is developed.The detection layer is considered as a sealed space and it is assumed that total current flows through the leak for the high resistivity of geomembrane liner.The leak current is regarded as a positive point current I and the other current source is-I.Electrical potential of an arbitrary point in detection layer satisfies Poisson equation. Experiments for detecting leaks in liner were carried out.Excellent agreement between experimental data and simulated model data validates the new model.Parametric curves for a single leak show that with optimum selection of field survey parameters leaks can be detected effectively.For multiple leaks,the simulated results indicate that they are detectable when leak separation is larger than measurement spacing. 相似文献
8.
对于静电驱动的亚微米及纳米尺度的谐振器,衍射效应将会使其驱动及振动频率的光学检测变得更加困难,为克服衍射效应的影响,设计、制作了新型纳机电谐振梁——H型梁,使其产生高频振荡.并制作了双端固支谐振器以进行比较.2种谐振梁的最小宽度和厚度分别为180和200nm.对这2种结构的机械振动特性进行了实验研究.谐振器的基波振荡频率在6.8～20MHz之间,远低于理论预估值.通过模拟仿真发现,过腐蚀是导致振动频率低于理论值的重要原因之一.实验还发现:2种谐振器的谐振频率之差随着梁的长度增加而下降;在室温下减小样品腔的压强后,谐振器的品质因数可以大大提高. 相似文献
9.
INTRODUCTION The problem of circular plates subjected to auniform load is one of the classical problems in elas-ticity theory,which also is encountered frequently inpractice.Timoshenko and Goodier(1970)presented athree-dimensional solution for uniformly loaded iso-tropic circular plates with simply supported edges.Analytical solutions of isotropic circular plates witheither clamped or simply supported edges subjectedto a uniform load,which were derived based on thinplate theory with Kirch… 相似文献
10.
With the development of computer simulation technique for room acoustics, diffuse reflection is considered more and more important.
In this paper, some models are developed by considering two diffuse factors in a room-diffuse reflection due to room surfaces
and scattering due to objects. The surface diffusion is treated by two different methods on the basis of probability analysis
or Energy Conservation Law, and the scattering among objects is simulated as a multiple random ray-tracing process. Thus the
sound pressure level distribution in a diffuse sound field can be calculated more precisely and easily. Agreement between
the computer simulation results and measurements shows the accuracy of the mathematical and physical model and the applicability
of the computer simulation methods. These models can be used in noise control engineering, as well as in the practice of acoustical
design. 相似文献
11.
A bi-harmonic potential function was constructed in this study. Love solution was employed to obtain analytical solutions of uniformly loaded plates with two different types of clamped edges. The treatment of clamped boundary conditions was the same as that adopted by Timoshenko and Goodier （1970）. The analytical solution for the first type of clamped boundary condition is identical with that obtained by Luo et al.（2004）, and the solutions for both types were compared with the FEM results and the calculations of thin plate theory. 相似文献
12.
隔声测量是绿色建筑评价的重要组成部分,建筑隔声是隔绝外界噪声的重要手段之一。因此建筑和建筑构件的隔声量测量技术的完善对降低噪声污染、促进人居声环境的改善有重要意义。混响时间是室内声学最重要、最精密的客观音质评价参量,用赛宾公式表达混响时间与房间的隔声量的相关性。以环境物理实验室为研究对象,运用切断声源法,对其混响时间和隔声量进行测量。结果显示,房间的混响时间均处于0.60~0.90 s的范围,且随频率的增加先减小再增大,于中高频段达到稳定值0.8 s,然后再小幅度减小。房间的隔声能力由表观隔声量与标准化声压级差表征,两者变化趋势一致,表现为随频率增加呈递增趋势,在测量区间由15 dB增加到30 dB。 相似文献
13.
Mechanical model of domestic gas explosion load 总被引：3，自引：0，他引：3
With the increase of domestic gas consumption in cities and towns in China,gas explo-sion accidents happened rather frequently,and many structures were damaged greatly.Rational physical design could protect structures from being destroyed,but the character of explosion load must be learned firstly by establishing a correct mechanical model to simulate vented gas explo-sions.The explosion process has been studied for many years towards the safety of chemical in-dustry equipments.The key problem of these studies was the equations usually involved some ad-justable parameters that must be evaluated by experimental data,and the procedure of calculation was extremely complicated,so the reliability of these studies was seriously limited.Based on these studies,a simple mathematical model was established in this paper by using energy conservation,mass conservation,gas state equation,adiabatic compression equation and gas venting equation.Explosion load must be estimated by considering the room layout; the rate of pressure rise was then corrected by using a turbulence factor,so the pressure-time curve could be obtained.By using this method,complicated calculation was avoided,while experimental and calculated results fitted fairly well.Some pressure-time curves in a typical rectangular room were calculated to inves-tigate the influences of different ignition locations,gas thickness,concentration,room size and venting area on the explosion pressure.The results indicated that: it was the most dangerous con-dition when being ignited in the geometry centre of the room; the greater the burning velocity,the worse the venting effect; the larger the venting pressure,the higher the peak pressure; the larger the venting area,the lower the peak pressure. 相似文献
14.
ＩＮＴＲＯＤＵＣＴＩＯＮＷｉｔｈｔｈｅｄｅｖｅｌｏｐｍｅｎｔｏｆｃｏｍｐｕｔｅｒｓｉｍｕｌａｔｉｏｎｔｅｃｈｎｉｑｕｅｆｏｒｒｏｏｍａｃｏｕｓｔｉｃｓ,ｎｅｗｍｏｄｅｌｓｈａｖｅｂｅｅｎｐｒｏｐｏｓｅｄｆｏｒｍｏｒｅｐｒｅｃｉｓｅｌｙｓｉｍｕｌａｔｉｎｇｓｏｕｎｄｆｉｅｌｄｓｔｏｒｅａｌｉｚｅａｕｒａｌｉｚａｔｉｏｎ .Ｔｈｅｃｏｍｐｕｔ ｅｒｈａｓｐｌａｙｅｄａｖｅｒｙｉｍｐｏｒｔａｎｔｒｏｌｅｉｎｔｈｅｒｅ ｓｅａｒｃｈｏｎｓｏｕｎｄｐｒｏｐａｇａｔｉｏｎ ,ｉｎｔｈｅｐｒｅｄｉｃｔｉｏｎｏｆｒｏ… 相似文献
15.
Learning abstract concepts such as sound often involves an ontological shift because to conceptualize sound transmission as a process of motion demands abandoning sound transmission as a transfer of matter. Thus, for students to be able to grasp and use a generalized model of sound transmission poses great challenges for them. This study involved 199 students aged 10–14. Their views about sound transmission were investigated before and after teaching by comparing their written answers about sound transfer in different media. The teaching was built on a research-based teaching–learning sequence (TLS), which was developed within a framework of design research. The analysis involved interpreting students' underlying theories of sound transmission, including the different conceptual categories that were found in their answers. The results indicated a shift in students' understandings from the use of a theory of matter before the intervention to embracing a theory of process afterwards. The described pattern was found in all groups of students irrespective of age. Thus, teaching about sound and sound transmission is fruitful already at the ages of 10–11. However, the older the students, the more advanced is their understanding of the process of motion. In conclusion, the use of a TLS about sound, hearing and auditory health promotes students' conceptualization of sound transmission as a process in all grades. The results also imply some crucial points in teaching and learning about the scientific content of sound. 相似文献
16.
Diesel particulate filter （DPF） is an important factor which influences the sound from exhaust system of an engine. In order to underst and the propagation law of sound wave and predictthe insertion loss in DPF, based on the general aero-dynamic equations and Darcy＇s law, an acoustic property calculation model of DPF is constructed. Propagation and attenuation characteristics of the forward and backward propagating acoustic waves in the close and open pipe of the filter are investigated. The theoretical model is combined with experiment to investigate sound attenuation property of DPF. The insertion loss obtained from the experiment is compared with that computed for a DPF. The results from the experiment and theoretical calculation agree well. 相似文献
17.
María Isabel Hernández Digna Couso Roser Pintó 《Journal of Science Education and Technology》2012,21(6):702-712
We believe that finding out how students think about certain topics that are covered in science classes should not be ??the end of the story?? but the starting point for planning lessons and designing materials. From this perspective, the research study presented here is intended to explore secondary school (15?C18?year old) students?? preconceptions of sound attenuation, and of the properties and internal structure of materials. Specifically, we analysed students?? explanations for the fact that some materials attenuate sound more than others. This study was conducted within a particular scenario, in which 72 students participated in laboratory sessions aimed at developing students?? understanding of the nature, propagation and attenuation of sound. From the analysis of students?? explanations, we could identify some conceptions of sound attenuation in materials (e.g. as a result of hindering the entrance of sound, or as a result of capturing sound). The results of this study also indicate that the role of properties of a material and the role of the internal structure that students associate with its acoustic behaviour depend on their conceptions of sound attenuation. We used these results as support for the design of a research-based teaching/learning sequence on the Acoustic Properties of Materials, which is intended to facilitate students?? overcoming the specific conceptual difficulties identified in this research study and promote students?? development of conceptual models of sound attenuation. 相似文献
18.
针对如何增加MIMO—OFDM系统数据传输速率的问题,本文研究了MIMO—OFDM系统中四种典型的自适应算法,并通过MATLAB仿真软件平台,对这四种自适应算法的性能进行比较分析,得出相应数据及结论．研究表明,在这四种算法中,自适应门限算法能分配到较多的比特数,且分配到高比特数情况的次数较多．另外还可看出,该算法能保证总发射功率恰如其分地运用到每个子载波上,而不是由于平均分配使得某些功率因不适当的运用而被浪费． 相似文献
19.
采用有限元软件AutoDyn,对TNT炸药起爆后爆炸冲击波遇到挡墙时的传播规律进行了三维数值模拟,分析了冲击波遇到挡墙时的反射高压及冲击波的环流汇聚作用。结果表明：冲击波遇到挡墙时将会产生反射高压;在比距离较小时,挡墙迎爆面的最大压力发生在挡墙底部;而随着比距离的增大,压力分布将沿挡墙高度趋于均匀。由于反射的作用,在挡墙前的地面上将会出现高压;当冲击波绕过挡墙时,在冲击波三个方向的绕射汇聚作用下,将会在墙后面一定区域内突然产生局部高压,并且随着传播的继续,这个区域不断的扩大,最后再次形成球面波传播。 相似文献
20.
史丹 《连云港职业技术学院学报》2006,19(4):33-35
一般而言工业化是一国或地区从落后走向现代化所必然要经历的阶段.总体上看,苏北地区工业化水平与全省平均水平相比有很大差距.加快工业化进程,是带动苏北地区经济持续、快速、健康发展的战略选择.优化提升苏北地区的产业结构,加快苏北工业化进程,必须从两方面着手,一是三次产业间的结构优化,二是三次产业内部的结构优化. 相似文献