1. Nonlinear acoustic propagation in bubbly liquids: Multiple scattering, softening and hardening phenomena

The weakly nonlinear propagation of acoustic waves in monodisperse bubbly liquids is investigated numerically. A hydrodynamic model based on the averaged two-phase fluid equations is coupled with the Rayleigh-Plesset equation to model the dynamics of bubbles at the local scale. The present model is validated in the linear regime by comparing with the Foldy approximation. The analysis of the pressure signals in the linear regime highlights two resonance frequencies: the Minnaert frequency and a multiple scatteringresonance that strongly depends on the bubble concentration. For weakly nonlinear regimes, the generation of higher harmonics is observed only for the Minnaert frequency. Linear combinations between the Minnaert harmonics and the multiple scatteringresonance are also observed. However, the most significant effect observed is the appearance of softening-hardening effects that share some similarities with those observed for sandstones or cracked materials. These effects are related to the multiple scatteringresonance. Downward or upward resonance frequency shifts can be observed depending on the characteristic of the incident wave when increasing the excitation amplitude. It is shown that the frequency shift can be explained assuming that the acoustic wave velocity depends on a law different from those usually encountered for sandstones or cracked materials.

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发布时间: 2016-04-11

2. Light and sound in silicon chips: The slower the better: New research combines sound and light waves in silicon chips to create a new type of signal processing

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Science News from research organizationsLight and sound in silicon chips: The slower the better. New research combines sound and light waves in silicon chips to create a new type of signal processing. Date: September 16, 2019 Source: Bar-Ilan University Summary: Acoustics is a missing dimension in silicon chips because acoustics can complete specific tasks that are difficult to do with electronics and optics alone. For the first time researchers have added this dimension to the standard s...

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发布时间: 2019-10-12

3. 英国海军新型猎雷声呐服役

国防科技网（81tech）讯： [英国国防部2004年3月26日报道]世界上最先进的水雷探测声呐按时于2004年3月17日在英国海军“赫沃思”号猎雷艇上服役，该声呐可从1000米外对足球大小的物体进行探测和分类。这种2193型声呐将提高英国“狩猎”级反水雷艇探测传统水雷和新的稳身水雷的能力。 该声呐采用先进宽带技术，可发射含有各种频率（不是常规声呐只使用一种频率）的声信号，从而极大提高了探测距离和精度。2193型声呐将安装在8艘“狩猎”级反水雷艇上，该艇上安装有最新的Nautis 3指挥控制系统。 该型声呐由泰利斯水下系统（英国）公司设计生产。 [中国船舶信息中心 曹一辉] 分享到： .

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发布时间: 2016-02-25

4. Stress-dependent ultrasonic scattering in polycrystalline materials

/content/asa/journal/jasa/139/2/10.1121/1.4941253 1. 1. D. I.Crecraft , “ The measurement of applied and residual stresses in metals using ultrasonic waves ,” J. Sound Vib. 5 , 173 –192 (1967 ). http://dx.doi.org/10.1016/0022-460X(67)90186-1 2. 2. D. M.Egle and D. E.Bray , “ Measurement of acoustoelastic and third-order elastic constants for rail steel ,” J. Acoust. Soc. Am. 60 , 741 –744 (1976 ). http://dx.doi.org/10.1121/1.381146 3. 3. G....

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发布时间: 2016-02-25

5. 基于时间反转MUSIC的奥氏体不锈钢超声成像分析

Austenitic stainless steel has been widely used in today’s nuclear power and some of the chemical industry, but it is still more difficult that research using appropriate method to detect the weld defects.Based on time reversal, the decomposition of the time-reversal operator algorithm and multiple signal classification were used to denoise and comparatively analyze the simulate signals with SNR of -5dB and -10dB. In the experiment, a 16 element ultrasonic phased array probe was used to d...

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发布时间: 2016-04-11

6. Scientists uncover genetic similarities among species that use sound to navigate

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Home.Biology.Plants & Animals. Home.Biology.Evolution.. . . October 4, 2019 Scientists uncover genetic similarities among species that use sound to navigate. by Krista Conger, Stanford University Medical Center Many bats use echolocation, but so do dolphins. Evolutionary adaptations that are shared by unrelated species arose in part due to identical, independently acquired genetic changes, a study found. Credit:...

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发布时间: 2019-10-12

7. K-SVD和OMP算法在超声信号去噪中的应用

A lot of noise exists in the on-site collected ultrasonic signals, which decreases the diagnostic accuracy of internal defects in materials. For solving this problem, a kind of ultrasonic echo signal denoising algorithm which based on the combination of the generalized K-singular value decomposition algorithm (K-SVD algorithm) and the orthogonal matching pursuit (OMP) algorithm was raised. In this method, using K-SVD algorithm,the Gabor dictionary was trained to become the ultra-complete ...

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发布时间: 2016-04-11

8. New research combines sound and light waves in silicon chips to create a new type of signal processing

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发布时间: 2019-10-12

9. BAE系统公司为机敏级潜艇定购2076型声纳

国防科技网（81tech）讯： 据BAE系统公司5月15日报道：英国机敏级潜艇主承包商最近同泰利斯水下系统公司就提供2076潜艇声呐系统签订一份合同。该声呐是一种主/被动搜索和攻击声呐设备，被指定用于机敏级潜艇。 该合同所提供的声呐将装备为英国最新生产的首批3艘机敏级潜艇--机敏号、伏击号、巧妙号。另外的4套2076声呐全套装备将用来装备4艘特拉法尔加级潜艇。BAE系统公司负责该项计划的常务董事称，2076声呐合同的签订是发展机敏级潜艇计划的主要里程碑。他还宣称为潜艇装备2076声呐毫无疑问是最好的解决方法，这将为特拉法尔加级潜艇提供卓越的性能，并使机敏级潜艇成为英国皇家海军技术最先进的在役潜艇。国防采办部长劳德·巴赫说，该型声呐系统将是英国皇家海军在水下作战技术方面处于领先的地位，标志着在潜艇能力方面迈进的重大一步，增强英国观察其他潜艇和水面舰艇目的。泰尔斯水下系统公司常务董事补充道：2076声呐系统由一套具有最先进技术的声呐分系统组成，这些系统使用声呐和处理技术方面最新的发展技术，大大的提高皇家海军在潜艇作战性能。 分享到： .

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发布时间: 2016-03-10

10. Concert halls with strong and lateral sound increase the emotional impact of orchestra music

An audience's auditory experience during a thrilling and emotive live symphony concert is an intertwined combination of the music and the acoustic response of the concert hall. Music in itself is known to elicit emotional pleasure, and at best, listening to music may evoke concrete psychophysiological responses. Certain concert halls have gained a reputation for superior acoustics, but despite the continuous research by a multitude of objective and subjective studies on room acoustics, the fundamental reason for the appreciation of some concert halls remains elusive. This study demonstrates that room acousticeffects contribute to the overall emotional experience of a musical performance. In two listening tests, the subjects listen to identical orchestra performances rendered in the acoustics of several concert halls. The emotional excitation during listening is measured in the first experiment, and in the second test, the subjects assess the experienced subjective impact by paired comparisons. The results showed that the sound of some traditional rectangular halls provides greater psychophysiological responses and subjective impact. These findings provide a quintessential explanation for these halls' success and reveal the overall significance of room acoustics for emotional experience in music performance.

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发布时间: 2016-03-23

11. Planes and vehicles main culprits masking iconic natural sounds in peaceful national parks

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Home.Earth.Environment.. . . October 2, 2019 Planes and vehicles main culprits masking iconic natural sounds in peaceful national parks. by Ecological Society of America A researcher sets up audio recording equipment on NPS lands. Credit: Rachel BuxtonU.S. national parks are full of natural sounds. In Rocky Mountain National Park, visitors might hear the bugle of elks. At Yellowstone National Park, wolves howl in the distance. ...

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发布时间: 2019-10-12

12. Auditory evoked potentials in the auditory system of a beluga whale Delphinapterus leucas to prolonged sound stimuli

The effects of prolonged (up to 1500 s) sound stimuli (tone pip trains) on evoked potentials (the rate following response, RFR) were investigated in a beluga whale. The stimuli (rhythmic tone pips) were of frequencies of 45, 64, and 90 kHz at levels from 20 to 60 dB above threshold. Two experimental protocols were used: short- and long-duration. For the short-duration protocol, the stimuli were 500-ms-long pip trains that repeated at a rate of 0.4 trains/s. For the long-duration protocol, the stimuli were continuous pip successions lasting up to 1500 s. The RFR amplitude gradually decreased by three to seven times from 10 ms to 1500 s of stimulation. Decrease of response amplitude during stimulation was approximately proportional to initial (at the start of stimulation) response amplitude. Therefore, even for low stimulus level (down to 20 dB above the baseline threshold) the response was never suppressed completely. The RFR amplitude decay that occurred during stimulation could be satisfactorily approximated by a combination of two exponents with time constants of 30−80 ms and 3.1−17.6 s. The role of adaptation in the described effects and the impact of noise on the acoustic orientation of odontocetes are discussed.

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发布时间: 2016-03-16

13. Small acoustically forced symmetric bodies in viscous fluids

The total force exerted on a small rigid body by an acoustic field in a viscous fluid is addressed analytically in the limit where the typical size of the particle is smaller than both the viscous diffusion length scale and the acoustic wavelength. In this low-frequency limit, such a force can be calculated provided the effect of the acoustic steady streaming is negligible. Using the Eulerian linear expansion of Lagrangian hydrodynamic quantities (velocity and pressure), the force on a small solid sphere free to move in an acoustic field is first calculated in the case of progressive and standing waves, and it is compared to past results. The proposed method is then extended to the case of more complex shapes with three planes of symmetry. For a symmetric body oriented with one of its axis along the wave direction, the acoustic force exerted by a progressive wave is affected by the particle shape at leading order. In contrast, for a standing wave (with the same orientation), the force experienced by the particle at leading order is the same as the one experienced by a sphere of same volume and density.

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发布时间: 2016-03-10

14. Analytical approach to transforming filter design for sound field recording and reproduction using circular arrays with a spherical baffle

A sound field recording and reproduction method using circular arrays of microphones and loudspeakers with a spherical baffle is proposed. The spherical baffle is an acoustically rigid object on which the microphone array is mounted. The driving signals of the loudspeakers must be obtained from the signals received by the microphones. A transform filter for this signal conversion is analytically derived, which is referred to as the wave field reconstruction filter. The proposed method using a spherical baffle is compared with methods using an array of directional microphones and a microphone array mounted on a cylindrical baffle. Numerical simulations indicated that the proposed method is advantageous for sound field recording and reproduction compared with the other two methods. The results of measurement experiments in a real environment are also demonstrated

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发布时间: 2016-03-10

15. 欧洲核子研究中心开始测试检测中微子的大型新技术原型

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主页.物理.普通物理. . . . 2019年10月10日，欧洲核子研究中心开始测试检测中微子的新技术的大型原型。 图为费米国家加速器实验室的库尔特·里塞尔曼，展示了在双相ProtoDUNE探测器上观测到的宇宙射线粘体所造的轨迹。可见，在液体的龙轨道中，通过相关的电磁活动，可以看见电位。信用： 原

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发布时间: 2019-10-12

16. 炫科技点亮第四届中国电子信息博览会

新华社深圳４月８日电（记者刘大江、白瑜）你知道机器人也在备战高考吗？今后３至５年内，中国研制的机器人高考成绩将超过一本线，日本研制的机器人预计２０２１年前考上东京大学……这些最前沿的人工智能技术，在８日于深圳开幕的第四届中国电子信息博览会上可一窥端倪。 该博览会由工业和信息化部、深圳市政府联合主办，是中国新一代信息技术产业的展示平台，也是目前亚洲规模最大的电子信息综合性博览会。 博览会上，炫科技无处不在。在开幕式之后举行“人工智能产业发展论坛”上，嘉宾在主席台上发言，主席台两侧电子大屏幕即时显示发言内容，这是科大讯飞的“听见”智能语音系统在发挥作用，可以将语音即时转换成文字，准确率达９５％以上。 ３０００件新产品、新技术、炫科技在博览会上轮番亮相：基于人工智能的机器人“公子小白”，可与人进行情感交流；在虚拟现实家...

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发布时间: 2016-04-11

17. 由声波上"冲浪"控制的单个电子的量子状态

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首页.物理.量子物理. . . 2019年10月10日 由声波"冲浪"控制的单个电子的量子状态。 剑桥大学信贷分校的莎拉·柯林斯：剑桥大学的研究人员已经成功地利用声波控制单个电子中的量子信息，这是朝着高效、强健的量子计算机方向迈出的重要一步。半导体。国际团队，包括...

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发布时间: 2019-10-12

18. Scientists observe how acoustic interactions change materials at the atomic level

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Science News from research organizationsScientists observe how acoustic interactions change materials at the atomic level. Date: September 24, 2019 Source: DOE/Argonne National Laboratory Summary: By using sound waves, scientists have begun to explore fundamental stress behaviors in a crystalline material that could form the basis for quantum information technologies. Share:FULL STORY When exposed to stress and strain, materials can display a wide range of different pr...

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发布时间: 2019-10-12

19. Binaural hearing in children using Gaussian enveloped and transposed tones

Children who use bilateral cochlear implants (BiCIs) show significantly poorer sound localization skills than their normal hearing (NH) peers. This difference has been attributed, in part, to the fact that cochlear implants(CIs) do not faithfully transmit interaural time differences(ITDs) and interaural level differences (ILDs), which are known to be important cues for sound localization. Interestingly, little is known about binaural sensitivity in NH children, in particular, with stimuli that constrain acoustic cues in a manner representative of CI processing. In order to better understand and evaluate binaural hearing in children with BiCIs, the authors first undertook a study on binaural sensitivity in NH children ages 8–10, and in adults. Experiments evaluated sound discrimination and lateralization using ITD and ILD cues, for stimuli with robust envelope cues, but poor representation of temporal fine structure. Stimuli were spondaic words, Gaussian-enveloped tone pulse trains (100 pulse-per-second), and transposed tones. Results showed that discrimination thresholds in children were adult-like (15–389 μs for ITDs and 0.5–6.0 dB for ILDs). However, lateralization based on the same binaural cues showed higher variability than seen in adults. Results are discussed in the context of factors that may be responsible for poor representation of binaural cues in bilaterally implanted children.

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发布时间: 2016-04-11

20. A sound strategy for gene expression

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Imaging of gene expression in live cells or tissues has largely relied on light-based strategies detecting fluorescence or luminescence, but poor transmission of light through tissues limits the depth that can be imaged. A new study reports a synthetic biology approach to encode an ultrasound-based gene expression reporter that is applicable to mammalian cells in vitro and in vivo. Credit: Chnit Siri Kan Ti N Cheiynghim/EyeEm/Getty To adopt ultrasound as a robust biomolecular readout, strategie...

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发布时间: 2019-10-12

21. 美国宇航局进行声爆测试探针飞行试验

国防科技网（81tech）讯：[据美国航空周刊和空间技术网站2016年3月25日报道]随着NASA研制X低声爆验证机计划的临近，NASA正加紧测试能够测量飞机产生声爆强度的空气探针，以改善低声爆设计工具和降低声爆强度。 由位于弗吉尼亚的鹰航空技术公司开发、NASA进行优化设计的“鹰航空声爆探针”3月份已经完成了在NASA的F-15B试验机上的6次飞行试验， 测试了F-15产生的声爆。试验中，该探针安装在F-15B机腹下的挂架上。试验结果将同2012年进行的NACA声爆探针测试数据进行对比。 NASA研究员迈克•弗雷德里克表示，“鹰航空声爆探针”的压力传感器安装在距鼻锥压力孔仅10厘米处，能够几乎实时测得压力变化。而过去进行的安 装在F-15B机鼻处的声爆探针，由于压力传感器在雷达罩后，距压力孔4.6米处，因此测量具有延迟。对于后期的测试，“鹰航空声爆探针”将会被安装在 F-15B或F-15D的机鼻处进行声爆测量。 据悉，上一代的探针从2009年开始陆续在F-15B上进行飞行测试。最近的飞行试验发现了上一代探针的缺陷并进行了改进，主要是增加了探针加热控制系统以保持探针在6...

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发布时间: 2016-04-11

22. Speed of sound in diseased liver observed by scanning acoustic microscopy with 80?MHz and 250?MHz

/content/asa/journal/jasa/139/1/10.1121/1.4940126 1. 1. Agemura , D. H. , O'Brien , W. D. , Olerud , J. E. , Chun , L. E. , and Eyre , D. E.(1990 ). “ Ultrasonic propagation properties of articular cartilage at 100 MHz ,” J. Acoust. Soc. Am. 87 , 1786 –1791 . http://dx.doi.org/10.1121/1.399427 2. 2. Akashi , N. , Kushibiki , J. , and Dunn , F.(2003 ). “ An analytic method of frequency dependence of acoustic properties of biological media in the VHF/UHF ra...

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发布时间: 2016-02-25

23. 世界舰艇声纳技术的现状与发展

当前位置: 首页» 资讯» 船舶工业» 中国船舶工业» 机电世界舰艇声纳技术的现状与发展。 发布日期:2009-12-08 核心提示:互联网声纳是利用在海洋中传播的声波来探测目标并对目标进行定位、识别和跟踪的。声纳技术是指各国... 国防科技网 (81tech) 讯:互联网声纳是利用在海洋中传播的声波来探测目标并对目标进行定位、识别和跟踪的。声纳技术是指各国海军为提高声纳的探测效能而开发和应用的技术。 一、20世纪声纳装备发展概述人类社会两次残酷的世界大战都发生在20世纪。一战期间为了对付德国人的潜艇攻击各国海军考虑了许多方法探测水下潜艇。其中包括热、磁、电磁以及声的方法只有声探测方法有效。从此声信息进入了海战场最雏形的信息战。最早出现的声纳是达? 芬奇管式的被动舰壳声纳和拖曳声纳，具有对目标的估距能力。为了适应武器设计高精度定位的需要，一战末期开发了主动回声测距声纳 (战后投入使用) 所用的电声换能器是朗之万式压电晶体换能器。声纳装备至今已有八十年以上的发展史。 一战之后各国加紧了声纳的研究

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发布时间: 2016-02-25

24. Seeing sound: Scientists observe how acoustic interactions change materials at the atomic level

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Home.Physics.Condensed Matter.. . . September 24, 2019 Seeing sound: Scientists observe how acoustic interactions change materials at the atomic level. by Jared Sagoff, Argonne National Laboratory From left, Argonne and University of Chicago scientists Joseph Heremans, Samuel Whiteley, Martin Holt, and Gary Wolfowicz stand by Argonne’s Hard X-ray Nanoprobe beamline, which was used for a new technique called stroboscopic Bragg diff...

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发布时间: 2019-10-12

25. 德国总理呼吁扩大对非洲地区武器出口 ― 国际防务快讯 ― 国防科技信息网 中国最权威的国防科技信息的专业门户 国际军事新闻 国内军事新闻 热点军事专题 中国独家的军事图片 军事视频

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[法国《防务宇航》2019年11月28日报道]    11月27日，德国总理安格拉?默克尔在国会发表讲话称，鉴于非洲部分地区局势，敦促部分国会议员重新考虑目前德国限制性武器出口政策，扩大向非洲地区武器出口规模，以维护德国自身国家利益。 她指出，俄罗斯近期与非洲国家在索契举行了首脑峰会，期间还举行了大型防务展，并且承诺向非洲国家采购俄制装备提供优惠价格。此外，她还指出，德国和法国已经同意启动于2018年七国峰会中签署的“萨赫勒安全倡议”（Sahel security initiative），以尽快稳定该地区的安全局势。（北方科技信息研究所 王睿） .

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发布时间: 2019-12-05

26. 定向传输水声通信网络邻节点发现机制

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摘要：针对水声通信网络拓扑不稳定的问题，本文对其邻节点发现机制进行了研究。邻节点发现机制将网络新增节点的邻节点分为全向传输范围内邻节点与定向传输范围内邻节点2类，全向传输范围内邻节...

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发布时间: 2019-10-12

27. Comparison of optical coherence tomography and high frequency ultrasound imaging in mice for the assessment of skin morphology and intradermal volumes | Scientific Reports

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Abstract.Optical coherence tomography (OCT) and high-frequency ultrasound (HFUS), two established imaging modalities in the field of dermatology, were evaluated and compared regarding their applicability for visualization of skin tissue morphology and quantification of murine intradermal structures. The accuracy and reproducibility of both methods were assessed ex vivo and in vivo using a standardized model for intradermal volumes based on injected soft tissue fillers. OCT revealed greater deta...

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发布时间: 2019-10-12

28. The sound insulation of single leaf finite size rectangular plywood panels with orthotropic frequency dependent bending stiffness

Current theories for predicting the sound insulation of orthotropic materials are limited to a small range of infinite panels. This paper presents a method that allows for the prediction of the sound insulation of a finite size orthotropic panel. This method uses an equation for the forced radiation impedance of a finite size rectangular panel. This approach produces an equation that has three nested integrals. The long numerical calculation times were reduced by using approximate formulas for the azimuthally averaged forced radiation impedance. This reduced the number of nested integrals from three to two. The resulting predictions are compared to results measured using two sample sizes of four different thicknesses of plywood and one sample size of another three different thicknesses of plywood. Plywood was used for all the tests because it is somewhat orthotropic. It was found during testing that the Young's moduli of the plywood were dependent on the frequency of excitation. The influence of the frequency dependent Young's moduli was then included in the prediction method. The experimental results were also compared with a simple isotropic prediction method.

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发布时间: 2016-02-25

29. 人工智能芯片之争：抢夺智能时代的入场券

作者： 赵广立 来源：中国科学报 发布时间：2016/8/23 9:23:48 选择字号：小 中大 . . 人工智能芯片之争：抢夺智能时代的入场券. . Xeon Phi芯片 图片来源：百度图片 ■本报记者 赵广立 当地时间8月17日，英特尔数据中心集团执行副总裁戴安·布莱恩特在开发者大会（IDF）上宣布，将在2017年推出专为机器深度学习设计的芯片——Xeon Phi，代号Knights Mill。在此之前，英特尔刚刚以4亿美元收购了一家专注深度学习开发平台研究的初创公司Nervana Systems。 业内人士指出，随着英特尔人工智能（AI）战略的快速推进，人工智能芯片“群雄逐鹿”的格局正在形成。 “无论传统芯片巨头如英特尔、英伟达、高通，还是互联网巨头如谷歌、FaceBook，以及类似于地平线、寒武纪等这样的新锐势力，大家竞争的焦点虽然是针对于人工智能应用的芯片上，但其实都在布局自己在未来智能时代的一席之地。”地平线机器人技术创始人兼CEO余凯在接受《中国科学报》记者...

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发布时间: 2016-08-25

30. Using velocity-induced acoustic oscillations as a standard ruler at cosmic dawn

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发布时间: 2019-10-12