摘要：Broadband sound sink/absorber via a structure with deep sub-wavelength thickness is of great and continuing interest in physics and engineering *** intuitive technique extensively used is to combine components(resonators)with quasi-perfect absorption to piece together a broad absorbing band,but the requirement of quasi-perfect absorption substantially places a very strict restriction on the impedance and thickness of the ***,we theoretically and experimentally demonstrate that a compact broadband acoustic sink that quasi-perfectly absorbs broadband arriving sound waves can be achieved with coherently coupled‘‘weak resonances"(resonant sound absorbing systems with low absorption peaks).Although each component exhibits rather low absorption peak alone,via manipulating the coherent coupling effect among the components,they collectively provide a remarkably improved performance over a wide frequency range with a significantly compressed *** illustrate the design principle,a hybrid metasurface utilizing the coaction of parallel and cascade couplings is presented,which possesses an average absorption coefficient of 0.957 in the quasi-perfect band(a>0:9)from 870 to 3224 Hz with a thickness of only 3.9 *** results open new avenues for the development of novel and highly efficient acoustic absorbers against low frequency noise,and more essentially,suggest an efficient approach towards on-demand acoustic impedance engineering in broadband.

摘要：Microfluidic device with patterned microstructures on the substrate surface was used to regulate cell adhesion,morphology,and functions in tissue *** developed a microfluidic device which employing microscale patterned microstructures to achieve enhanced cell adhesion and *** hydrogel substrates with micro-wavy and lattice-patterned microstructures were fabricated using standing surface acoustic waves and ultraviolet *** seeding the L929 mouse fibroblast cells onto the patterned substrate of the microfluidic device,we determined that the viability and proliferation rate of cell migration can be greatly ***,L929 cells showed two types of gathering modes after 48 h of *** growth was guided by the patterned substrate used in the microfluidic device and showed differences in the location ***,the developed microfluidic device with patterned microstructures can extend the application of in vitro cell culturing for future drug development and disease diagnosis.

摘要：This paper develops a sampling method to estimate the integral of a function of the area with a strategy to cover the area with parallel lines of observation. This sampling strategy is special in that lines very close to each other are selected much more seldom than under a uniformly random design for the positions of the parallel lines. It is also special in that the positions of some of the lines are deterministic. Two different variance estimators are derived and investigated by sampling different man made signal functions. They show different properties in that the estimator that estimate the biggest variance gives an error interval that, in some situations, may be more than ten times the error interval computed from the other estimator. It is also obvious that the second estimator underestimates the variance. The author has not succeeded to derive an expression for the expectation of this estimator. This work is motivated towards finding the variance of acoustic abundance estimates.

摘要：This paper designs an underwater acoustic communication system based on tamed spread spectrum and Frequency Hopping Multiple Access (FHMA) for multiple underwater vehicles. In this system, multiple underwater vehicles can communicate with the console on the water surface simultaneously successfully. The communication system is com-posed of tamed spread spectrum modulation and demodulation, frequency hopping modulation and demodulation with synchronization function, 4FSK modulation and demodulation and Rake Receiver. In order to make the system more feasible, underwater channel and the effect of user number on Bit Error Ratio (BER) are also taken into account. The simulation results indicate that it is feasible to use this system to accomplish underwater communication reliably for multiple users due to the low BER.

摘要：Through analysis on characteristic of highway traffic noise and pollution-treating and noise-reducing mechanism,the paper had illustrated feasibility and advantage to reduce traffic noise along highway by making use of plant acoustic barrier,introduced design model and methods of plant acoustic barrier,and principles and scope for plants' *** this basis,by taking K37+100-K37+250 section of Yunnan Chuda Highway for example,application of plant acoustic barrier had been studied,general situation and design schemes of pilot project analyzed,and some matters needing attention *** on the analysis of a large amount of statistical data and researches on pilot project of noise-reducing by plants along Yunnan Chuda Highway,it hoped to provide reference for similar engineering projects.

摘要：德国转盘制造商acoustic Soljd公司最近发布了由设计师Bruno Ferreni设计的WTB I音箱。WTBI音箱系由一对主音箱和一只有源低音音箱构成。它们都装饰以漂亮的木皮，主音箱的箱体有着波导线形的设计外形。它们的单元和分频网络进行了精细的微调，保证线性特征极佳的120阻抗和高达95dB／W／m的灵敏度。这使得音箱很容易被推动，8W的功放就能把它们推开。加上低音模块后整套系统的频率响应范围为25Hz-25kHz。

摘要：Within previous EU projects, possible modifications to the engine components have been investigated, that would allow for an optimised aerodynamic or acoustic design of the EGV （exit guide vanes） of the TEC （turbine exit casing）. However, the engine weight should not be increased and the aerodynamic performance must be at least the same. This paper compares the sound power level of a state-of-the-art TEC （reference TEC） with typical EGVs with an aerodynamically optimised TEC configuration for the engine operating point approach. It is shown that a significant weight reduction （only bladings considered） and reduction in engine length can be achieved but the sound power level for the fundamental tone （lst blade passing frequency） for this acoustically important operating point is increased. It is also shown that the losses of the aerodynamical optimised EGVs are higher for this off design point but significantly lower at the aero design point. Measurements were conducted in the STTF （subsonic test turbine facility） at the Institute for Thermal Turbo machinery and Machine Dynamics, Graz University of Technology. The inlet guide vanes, the LPT （low pressure turbine） stage, and the EGVs have been designed by MTU Aero Engines.

摘要：针对MEMS仿鱼侧线矢量水听器提出三种封装结构,即采用聚氨酯材料制成的透声帽封装结构,透声帽内衬笼状支撑体的封装结构,透声帽内衬瓣状支撑体的封装结构。采用ANSYS有限元建立三维封装模型并进行模态仿真,得出其固有频率分别为875 Hz、2 926 Hz、3 006 Hz。采用*** acoustic进行声衰减仿真并通过试验验证最终得出:内衬支撑体的封装结构,其有效带宽响应比无支撑体的透声帽封装结构宽2.2 kHz左右,同时,实验表明瓣状支撑体的收缩瓣状部分具有聚能效应,这种封装结构的水听器灵敏度比其他两种封装结构在相同频率点处高8 dB～12 dB。

摘要：为了分析水下声学无线传感器网络在受到干扰情况下的性能,介绍了影响网络性能的相关干扰因素,设计了物理层水声通信干扰模型,建立了基于频率相关的路径损耗和Ricean衰减的信道模型,研究了可作为网络连通标志的覆盖范围、端到端帧误差概率、功率和带宽需求之间的关系,分析了节点受同层其他节点通信干扰下的网络性能。通过仿真实验验证了所设计模型的可行性。实验数据表明,通过优化通信工作功率和节点密度,能够确保网络正常运行,提高网络的可靠性。

摘要：The?mine geostress measurement is the indispensable key to safe and efficient production of the mine. Currently, stress relief method, hydraulic fracturing method and acoustic emission method are widely used in mine geostress test fields. As deficiencies of the above several methods, the author designed a detailed borehole acoustic program for the tectonic fault conditions of a mine in Huainan, and got geostress parameter values according to the combination of site measured velocity values and laboratory tests.