A Simulation of the Response of a Sounding Temperature Sensor Based on the Combination of a Genetic Algorithm and Computational Fluid Dynamics

The present study aims at improving the accuracy of weather forecast by providing useful information on the behavior and response of a sounding temperature sensor.A hybrid approach relying on Computational Fluid Dynamics and a genetic algorithm(GA)is used to simulate the system represented by the bead thermistor and the surrounding air.In particular,the influence of different lead angles,sensor lead length,and lead number is considered.The results have shown that when the length of the lead wire of the bead thermistor is increased,the radiation temperature rise is reduced;when the number of lead wire is four and the angle between the lead wires is 180°,the solar radiation angle has a scarce influence on the radiation temperature rise of the sounding temperature sensor.

Dynamics of electromagnetic slip coupling for hydraulic power steering application and its energy-saving characteristics

To improve high-speed road feel and enhance energetic efficiency of hydraulic power steering(HPS) system in heavy-duty vehicles, an electromagnetic slip coupling(ESC) was applied to the steering system, which regulated discharge flow of steering pump to realize variable assist characteristic as well as uniquely transfer on-demand power from engine to steering pump. The model of ESC was established and the dynamic characteristics of ESC were presented by the way of simulation and experiment. Upon the layout of the assist characteristics, output torque of ESC was derived. Based on the ESC model, the output torque characteristics of ESC were simulated under steering situation and straight driving situation, respectively. The consistency of simulated ESC output torque and the one deduced from assist characteristics verifies the correctness of the ESC dynamic model. To illustrate energy saving characteristics of ESC-HPS, energy consumption comparison of ESC-HPS and conventional HPS was carried out qualitatively and quantitatively. It follows that the energy consumption of ESC-HPS decreases by 50% compared with that of HPS.

A Comparison on the Localization Performance of Static and Dynamic Binaural Ambisonics Reproduction with Different Order

Ambisonics is a series of spatial sound reproduction system based on spatial harmonics decomposition and each order approximation of sound field.Ambisonics signals are originally intended for loudspeakers reproduction.By using head-related transfer functions(HRTFs)filters,binaural Ambisonics converts the Ambisonics signals for static or dynamic headphone reproduction.In present work,the performances of static and dynamic binaural Ambisonics reproduction are evaluated and compared.The mean binaural pressure errors across target source directions are first analyzed.Then a virtual source localization experiment is conducted,and the localization performances are evaluated by analyzing the percentages of front-back and up-down confusion,the mean angle error and discreteness in the localization results.The results indicate that binaural Ambsonics reproduction with insufficiently high order(for example,5-10 order)is unable to recreate correct high-frequency magnitude spectra in binaural pressures,resulting in degradation in localization for static reproduction.Because dynamic localization cue is included,dynamic binaural Ambisoncis reproduction yields obviously better localization performance than static reproduction with the same order.Even a 3-order dynamic binaural Ambisoncis reproduction exhibits appropriate localizations performance.

基于气泡统一方程的声场双气泡耦合作用研究

针对声致空化现象中双气泡相互作用力展开了研究。本文基于气泡动力学的基本理论,将气泡统一方程应用到声场中双气泡的耦合作用研究中,建立了可用于计算声场中多气泡耦合的理论模型,并以此研究了不同类型的声场中双气泡次Bjerknes力的变化趋势。研究结果表明:在声压幅值较小的行进波声场中,对于非线性脉动的双气泡,其相互作用现象不仅与声场参数相关,还会受到双气泡初始体积比的影响。若固定其中一个气泡的初始体积,同时改变另一个气泡的初始体积,则双气泡间第1周期内的次Bjerknes力会在初始体积相等时达到第1个极值,随后呈现周期性的起伏,并在总体上呈增大趋势;而双气泡相互作用在声压幅值较大的行进波声场中会随初始半径比的增大持续增强,且周期性的起伏现象并不明显。在驻波声场中靠近波节的位置也能观测到这一现象。此外,本文还探究了非线性振动的双气泡在具有相同频率、不同声压幅值的组合波声场中的耦合效应。本文的研究可为声场中双气泡相互耦合作用以及气泡群动力学相关应用提供理论基础。

基于时频融合特征的肺动脉高压心音分类模型

先心病相关肺动脉高压是一种严重的心血管疾病,致死率高,对其进行早期筛查与识别对于治愈尤为重要。目前临床是通过右心导管术确诊,此为有创检查,不便于在大规模筛查中采用,研究一种无创便捷的识别方法迫在眉睫。文中建立了一种时频融合的心音分类模型。首先对心音信号进行预处理,然后使用融合滤波器组对信号进行转换并求取动态时频特征,最后将得到的融合特征参数输入表格式先验数据拟合网络(TabPFN)中进行分类识别。实验结果表明,该算法在正常、CHD-PAH和CHD中的平均准确率、精确率、灵敏度、特异度和F1分别为92.21%,92.15%,92.15%,96.11%,92.14%。对于先心病相关肺动脉高压的早期筛查与识别具有重要意义。

提高煤层气直井动液面解释精度方法研究与应用

煤层气井动液面解释精度对于煤层气井精细化排采管控至关重要,本文对比了接箍法、音标法及声速法等测液面方法的优缺点,分析了影响动液面解释精度的主控因素为井筒温度和气泡段,从而提出了一种提高动液面解释精度的新方法。此方法综合考虑了影响动液面解释精度的各个要素,能够依据所解释液面较为准确地反映煤层气井的井底流压,克服了前期其它方法所存在的一系列问题,为煤层气井精细化排采管控提供保障。

高速铁路声屏障动力特性试验与理论研究

研究目的:为更好地指导高速铁路声屏障结构设计与性能评估,通过开展声屏障结构动力响应现场试验,分析动力作用的传递方式,识别钢立柱与单元板等主要构件的动力行为,揭示声屏障动力作用机理,并进一步构建声屏障非线性动力分析模型,讨论板-柱连接刚度对结构动力性能的影响,研究声屏障结构频响特性,提出声屏障动力性能提升的相关建议。研究结论:(1)列车气动荷载作用下,立柱和单元板分别以弯曲振动和刚体运动为主,结构呈现非线性振动特征;(2)提出的高速铁路声屏障结构动力分析模型揭示了非线性振动作用机理,理论分析与现场实测结果基本吻合;(3)板-柱连接刚度是表征单元板约束状态和影响结构动力响应的关键参数,建议增加板-柱连接刚度相关控制要求;(4)声屏障结构动力分析方法可用于指导声屏障结构的优化设计与性能评估。

宽频带薄膜型声学超材料隔声性能研究

针对汽车前围板中低频段隔声性能有待优化对问题,提出一种以“X”形摆臂为中心质量块的薄膜声学超材料结构,使用COMSOL仿真软件中声固耦合模块对其结构整体声传递损失曲线(Sound Transmission Loss,STL)、薄膜表面平均法向位移、等效参数、耦合振动模态以及影响隔声量因素、调控规律进行有限元分析。结果表明:“X”形中心质量块薄膜声学超材料结构具有优异隔声频率带宽及隔声量幅值,带宽接近1332 Hz,隔声量峰值为54 dB;新结构中“X”形摆臂能兼并由四周质量块产生的不连续隔声峰,从而拓宽隔声频带,提高结构整体隔声性能;增大薄膜厚度和预紧力会使STL曲线整体向高频方向移动,增大“X”形摆臂弹性模量仅会使STL曲线第二隔声谷向高频方向产生小范围移动;其与钢板组成的复合结构能有效提高前围板平均隔声量。相关研究拓展了采用薄膜型声学超材料结构进行中低频段噪声治理的工程应用领域。

Customized Optimization for Vehicle Acoustic Statistical Energy Analysis

Statistical Energy Analysis(SEA) is one of the conventional tools for predicting vehicle high-frequency acoustic responses.This study proposes a new method that can provide customized optimization solutions to meet NVH targets based on the specific needs of different project teams during the initial project stages.This approach innovatively integrates dynamic optimization,Radial Basis Function(RBF),and Fuzzy Design Variables Genetic Algorithm(FDVGA) into the optimization process of Statistical Energy Analysis(SEA),and also takes vehicle sheet metal into account in the optimization of sound packages.In the implementation process,a correlation model is established through Python scripts to link material density with acoustic parameters,weight,and cost.By combining Optimus and VaOne software,an optimization design workflow is constructed and the optimization design process is successfully executed.Under various constraints related to acoustic performance,weight and cost,a globally optimal design is achieved.This technology has been effectively applied in the field of Battery Electric Vehicle(BEV).

动态听觉定位因素及其在空间声重放的作用

听觉定位机理是生理和心理声学的重要研究内容,在空间声技术方面有重要的作用。听觉定位是多因素(如双耳时间差、双耳声级差、个性化谱因素等)协同作用的结果,但各种因素所提供的信息有一定的冗余。听觉侧向定位机理已比较明确,主要是双耳时间差和双耳声级差的作用,特别是低频双耳时间差起主导作用。但前后和垂直定位机理的一些问题有待解决与澄清。虽然目前已确认个性化谱因素和头部转动带来的动态听觉定位因素提供了前后和垂直定位的信息,并且自从1940年Wallach提出了动态因素的经典假设以来,一直有不少实验从各方面证实了动态因素对听觉定位的作用;但总体上,动态因素的作用特别是对垂直定位的作用常常被低估,甚至较普遍地认为个性化谱因素起了完全主导的作用。听觉定位机理作为空间声技术的心理声学基础,如果假设前提不正确,将无法解析一些重要的实验事实,也无法解决一些普遍存在的问题。目前空间声技术面临的许多问题和误区多数都和动态因素密切相关。文章综述了有关动态听觉定位因素的研究与发展,特别是近年国际上和作者课题组的系列工作,并将其用于分析和解决空间声重放(包括双耳重放、多通路三维空间声和Ambisonics)的一些重要的共性问题,文中最后讨论了存在问题与研究前景。

玉米杂交种花丝活力及其结实性动态研究

为了明确玉米杂交种花丝活力及不同日龄花丝结实率的动态变化规律,更好的为玉米育种和玉米生产提供理论依据。本研究选用玉米杂交种‘永优1573’、‘永优1583’和‘郑单958’为试验材料,测定其花丝日吐丝数量和吐丝长度、不同日龄花丝结实率和授粉果穗穗部性状等相关指标。结果显示玉米杂交种日吐丝数量呈快增-慢增的变化趋势,日吐丝长度峰值在吐丝第2天。随着吐丝日数增加,授粉后果穗的穗长、穗粗、穗粒重和结实率基本呈先增后降的动态变化,其中穗粗峰值出现在吐丝第4~5天,穗长、穗粒重和结实率峰值均出现在吐丝的第6~7天,品种间有差异;吐丝第1~4天授粉百粒重均高于对照,有秃尖且逐日减小。研究结果所反映的花丝活力及其授粉结实率的变化规律无论在玉米高效育种还是在大田生产中都具有一定的参考性,从而实现高产的育种目标。

多工况下桥梁伸缩装置的动态特性及噪声评估

对某新型160型模数式桥梁伸缩装置车辆行驶噪声进行了研究。为获得不同工况车辆驶过时系统响应规律,通过ANSYS分别对整体结构做瞬态分析、对中梁、边梁型钢做模态分析进行确定;之后将响应规律转化为声学激励。联合有限元法以及边界元法,利用ANSYS Workbench中Harmonic Acoustic模块进行声学分析,得到人耳敏感频率段不同远场处A声级曲线,最大A声级出现频率以及伸缩装置适宜安装位置。为验证仿真结果可靠性,与文献试验结果进行对比。结果表明,上述方法可以有效地评估伸缩装置车辆行驶噪声,结果具有较高可靠性。

基于多体动力学的汽轮机振动声辐射机理及传递路径

采用多体动力学方法进行汽轮机机械振动激励源精确分析,在激励源分析结果的基础上研究低频激励下的机组振动响应,并采用声传递向量(Acoustic Transfer Vector,ATV)方法研究汽轮机组表面与外场辐射的声压传递贡献量,从多体动力学的角度并结合流固耦合的方法综合分析汽轮机组振动噪声产生机理并研究噪声典型传递路径。研究结果表明,旋转激励源为汽轮机组的主要振动激励源,在低频段汽轮机组辐射模式为单极子,在中高频段汽轮机组辐射模式为偶极子。由噪声辐射的指向性极坐标图可知,在不同高度处噪声指向性相似,并都在长度方向上取得噪声声压级较大值,具有较强的指向性。计算方法对汽轮机组减振降噪研究具有一定的指导意义。

孔内深层超强夯法处理厚层人工回填土的应用研究

介绍了孔内深层超强夯法(SDDC)的基本原理,并将SDDC工法运用于处理某机场内厚层人工回填土地基,对无机固体废料进行了资源化回收利用。通过复合地基载荷试验、标准贯入试验和重型动力触探试验对SDDC施工质量进行检测,对SDDC桩体和桩间土的承载力效果进行评价。结果表明,经SDDC工法处理后的复合地基均匀性较好,承载力显著提高,达到工程使用要求。

某纯电厢式微卡高速轰隆声优化改进研究

针对某纯电厢式微卡在高速行驶时产生的轰隆声问题,通过仿真分析与道路测试相结合的思路,识别出轰隆声的特征与产生机理:高速行驶下气流通过车身与货厢间隙进入导流罩内部腔体,导致腔体内空气产生自激振荡与板壁件共振耦合,在驾驶室内产生具有能量高、频率低、频谱宽特征的脉动声压。通过对车身结构加强、增加声学包、货厢间隙调整、导流罩外形优化等方案的验证,最终确定了导流罩外形优化的可工程化方案,经实车道路测试与评价,相比原基础状态,车内80~120 Hz频段驾驶员右耳噪声降低约3.9 dB(A),问题得到解决,并为后续气动噪声优化提供了参考。

A method for visualizing sound propagation in solids and liquids

A new method for visualizing sound propagation in solids and liquids is described in this paper. The method can show the sound propagation process dynamically in two dimensions. Compared with Schlieren method and dynamic photo-elastic method, this method cannot only show the sound field distribution in liquid and solid at different time moments, but also can be applied to non-transparent solid. In addition, it does not strictly require small residual stress of the sample. The sample can, therefore, be easily made. Because the acoustic field is obtained by indirect measurements, the recording can be affected by the after-shock of the receiving sensor and is prone to the influence of the direct wave of the liquid. Putting an aluminum plate into a liquid, we recorded the compression wave, shear wave and surface wave in the aluminum and, in the liquid we also recorded the direct wave and three head waves, which are directly coupled with the compression wave, shear wave and surface wave respectively. The recording clearly depicts the coupling relationship of the sound waves through the interface between the aluminum and the liquid. Putting a plexiglass into a liquid, we also recorded the sound waves in the plexiglass and the coupling relationship between the sound waves in the two mediums.

A General Model for Analysis of Sound Radiation from Orthogonally Stiffened Laminated Composite Plates

A general theoretical model is developed to investigate the sound radiation from an infinite orthogonally stiffened plate under point excitation force. The plate can be metallic or composite, and fluid loading is also considered in the research. The first order shear deformation theory is used to account for the transverse shear deformation. The motion of the equally spaced stiffeners is examined by considering their bending vibrations and torsional movements. Based on the periodic structure theory and the concepts of the equivalent dynamic flexibility of the plate, the generalized vibro-acoustic equation of the model is obtained by applying the Fourier transform method. The generalized model that can be solved numerically is validated by comparing model predictions with the existing results. Numerical calculations are performed to investigate the effects of the location of the excitation, the spacing of the stiffeners, the plate thickness, the strengthening form and the fiber orientation on the sound radiation characteristic of the orthogonaUy stiffened plate, and some practical conclusions are drawn from these parameter studies.

动液面深度检测中两个关键问题的研究进展

为了确保油田安全生产,满足提产增效的需求,实时检测井下动液面深度具有重要的意义。当采用声波法测量动液面深度时,需要解决套管内声速的计算和声波旅行时间的获取这两个关键问题。围绕该问题,归纳总结了近年来该领域取得的进展和成果,梳理了众多文献间的区别和联系。在此基础上,利用油田现场采集的声波信号对一些方法进行了复现。结果表明:对于不同环境的油井,上述方法存在明显的适应性差异。最后分析了当前研究的不足,并对两个关键问题的未来研究方向做出了展望。研究成果为特定环境下的井下声波信号处理提供了详细的解决方案,对于快速检索井下声波信号的处理方法有积极作用,具有一定的理论价值和重要的现实意义。

中空玻璃微珠填充聚氨酯发泡材料的吸声性能与动态力学性能研究

以聚氨酯(PU)为基体、磷酸三甲酚酯(TCP)为增塑剂、中空玻璃微珠(HGB)和偶氮二甲酰胺(AC发泡剂)为填料,采用熔融共混法制备了软质PU/TCP、PU/TCP/HGB、PU/TCP/HGB/AC材料,研究了增塑剂TCP、填料HGB和AC发泡剂的含量对PU材料的吸声性能和动态力学性能的影响。结果表明,在一定范围内,增塑剂TCP、填料HGB和AC发泡剂的加入显著提升了复合材料的吸声性能,当TCP含量为25%(质量分数,下同)、HGB含量为10%、AC含量为2%时,材料的吸声性能最佳,平均吸声系数达到0.29,且频率为1 714 Hz时吸声系数最大,为0.55;以半峰宽衡量材料的吸声频率宽度,发现在一定范围内增塑剂TCP、填料HGB和AC发泡剂对半峰宽的长度分别有减少、增加的作用,为制备轻质宽频吸声材料提供了实验依据;对PU/TCP、PU/TCP/HGB材料的动态力学性能分析进一步验证了选用25%TCP和10%HGB配比对材料整体性能调控的合理性。

声波对煤粉燃烧特性的影响:研究进展与展望

“双碳”目标的实现对煤炭的清洁高效利用提出了更高的要求。因此,探索煤粉新型清洁高效燃烧技术具有重要意义。声学作为一门基础性和交叉性极强的学科,近年来已渗透到几乎所有重要的自然科学和工程技术领域。尤其在燃煤电站锅炉中,声学技术的应用受到了广泛关注和研究,如基于声学原理的炉内温度场重建、测流、泄漏检测及声波除灰、声波团聚等技术。以上声学技术的研究和应用均涉及到声波传播过程中产生的声物理和化学效应。有关声场作用下煤粉颗粒燃烧特性的研究已有诸多报道,指出利用声波的物理化学效应可以为煤粉颗粒清洁高效燃烧提供新的技术手段。声波助燃技术已被证实是一种高效节能、清洁环保的新型燃烧技术,具有较大潜力。因此,在节能减排政策的高要求下,声波助燃技术在燃煤电站锅炉中的应用推广与发展研究应当得到足够的重视。目前针对声波影响煤粉颗粒燃烧的基础理论研究尚不完善,对声波物理化学效应的作用机制阐述不清。已有的文献中对声波影响煤粉燃烧的研究鲜见专著和综述性文章介绍。鉴于此,本研究较为全面地介绍了声波影响煤粉燃烧的作用机制,分析总结了国内外声波影响煤粉颗粒燃烧的研究现状,厘清了声波影响煤粉颗粒燃烧特性的主要技术研究路线,以便系统了解声波助燃的对象、方法、原理和实际应用。