Comparison of Rehabilitation Outcomes with Acoustic Radiation Force (ARFI) Elastosonography in Hemiplegic Patients Treated with Neuromuscular Electrical Stimulation

To evaluate the gastrocnemius/soleus and biceps brachii muscle stiffness by Acoustic Radiation Force Impulse (ARFI) elastography in the hemiplegia patients, sixty patients with hemiplegia after stroke were recruited. Baseline data were collected including age, gender, body mass index, education level, dominant side, affected side, time since stroke, stroke etiology. All patients were evaluated with before treatment and posttreatment with Broonstroom staging, Modified Ashworth spasticity scale, and Functional Independence Measures scale. The patient was divided into 3 groups: 1) Neuromuscular electrical stimulation group, 2) Rehabilitation group, 3) Neurumusculer electrical stimulation + Rehabilitation group. Affected and unaffected side biceps and gastrocnemius, ARFI elastography measurements were used to measure thickness and elastic values. In addition, before and after treatment, length and thickness were measured from all patients. Of the 60 subjects, 28 were female (46.7%) and 32 (53.3%) were males, with an average age of 58.42 ± 9.03 years. There was a significant difference between the upper and lower limbs after the treatment in terms of Brunstroom staging. In terms of Modified Ashworth scale, there was a significant difference in lower extremity only after treatment. When compared to the affected/unaffected side, before and after treatment, there was a significant difference in the measurements in both the medial gastrocnemius and the lateral gastrocnemius in all three groups. Further research with larger numbers of patients for longer periods is needed to clarify the relationship between the muscle hardness and degree of spasticity.

Combined optical fiber interferometric sensors for the detection of acoustic emission

A type of combined optical fiber interferometric acoustic emission sensor is proposed. The sensor can be independent on the laser source and make light interference by matching the lengths of two arms,so it can be used to monitor the health of large structure. Theoretical analyses indicate that the system can be equivalent to the Michelson interferometer with two optical fiber loop reflectors,and its sensitivity has been remarkably increased because of the decrease of the losses of light energy. PZT is powered by DC regulator to control the operating point of the system,so the system can accurately detect feeble vibration which is generated by ultrasonic waves propagating on the surface of solid. The amplitude and the frequency of feeble vibration signal are obtained by detecting the output light intensity of interferometer and using Fourier transform technique. The results indicate that the system can be used to detect the acoustic emission signals by the frequency characteristics.

A new brain stimulation method: Noninvasive transcranial magneto–acoustical stimulation

We investigate transcranial magneto–acoustical stimulation（TMAS） for noninvasive brain neuromodulation in vivo.TMAS as a novel technique uses an ultrasound wave to induce an electric current in the brain tissue in the static magnetic field. It has the advantage of high spatial resolution and penetration depth. The mechanism of TMAS onto a neuron is analyzed by combining the TMAS principle and Hodgkin–Huxley neuron model. The anesthetized rats are stimulated by TMAS, resulting in the local field potentials which are recorded and analyzed. The simulation results show that TMAS can induce neuronal action potential. The experimental results indicate that TMAS can not only increase the amplitude of local field potentials but also enhance the effect of focused ultrasound stimulation on the neuromodulation. In summary, TMAS can accomplish brain neuromodulation, suggesting a potentially powerful noninvasive stimulation method to interfere with brain rhythms for diagnostic and therapeutic purposes.

Effect of Fluid Electrical Property Changes on Surface Transverse Wave Sensors

A fluid sensor based on the surface transverse wave (STW) delay line on ST-cut quartz has been developed and tested in a large number of fluids with different viscosity and permittivity levels.Influence of fluid mechanical and electrical properties on the sensor's response has been determined and the sensor's performance has been compared with a bulk acoustic wave (BAW) viscosity sensor.The result shows that the viscosity sensitivity of the developed STW sensor represented by the signal to noise ratio is lower than that of a 5 MHz BAW sensor.Applications of the sensor in detecting the quality of industrial fluids are discussed.

Nondestructive Testing Electrical Methods for Sensing Damages in Cement Mortar Beams

This paper discusses the experimental results of concurrently measured Electrical and Acoustic Emissions in order to evaluate the mechanical health status of cement mortar beams subjected to three-point bending mechanical tests. In particular, the Electrical Resistance and the Electrical Current emissions are recorded concurrent with Acoustic Emissions and the experimental results are discussed under the concept of crack initiation and propagation processes. For the first time, the electrodes that are used for conducting the measurements are placed in the bulk of the specimen, near the tensile zone, during its preparation. The damage evolution is examined by monitoring the fractional change of the Electrical Resistance and the variation of the Electrical Current in combination with the Acoustic Emission recordings.

Systematical Development of NVH Engineering for Vehicle Electrical Powertrain Based on an Optimized V-Model

For systematical NVH development of vehicle (especially for mass-production passenger vehicles) electric powertrain, an optimized V-Model is designed and has been implemented in the entire component-vehicle development, which integrates three individual branches: simulation, validation and optimization. Compared to the V-models in the traditional sense, this optimized V-model is not only driven by requirement and task accomplishment but also maximum optimization of NVH system performance. In this case, developing procedures are capable to be efficiently iterated and the NVH engineering can be expanded into 3D with this V-model.

Acoustic carrier signal transmission technology and its potential for in-site monitoring of sliding electrical contact used in gas-insulated switchgear/gas-insulated transmission line

A wireless signal transmission technology based on acoustic carrier is proposed,which overcomes the limitation of electromagnetic signal shielding and shows great potential for in-site monitoring of sliding electrical contact used in gas-insulated switchgear(GIS)/gasinsulated transmission line(GIL).Here,the state parameter of the sliding electrical contact is modulated onto the frequency domain of an ultrasound wave.As a mechanical wave,the ultrasonic wave is immune to electromagnetic shielding,so that it could carry the sensing signal to penetrate the metal shielding layer and transmit to the external terminals of GIS/GIL.The principle and signal modulation process of the acoustic carrier based transmission system have been demonstrated in detail.Both simulation and experiment have been conducted to analyse the system characteristics as well as optimise the system configuration.As a proof-of-concept application,the in situ and on-line monitoring of the thermal rise of a slide electrical contact both in a current loading equivalent model and a prototype of GIS is demonstrated.Experimental results fit well with the physical process,and show a good measurement accuracy of 0.6%and tem-perature sensitivity of 400 Hz/℃.

The Forward and Inverse Problem Based on Magneto-Acoustic Tomography with Current Injection

The Magneto-acoustic Tomography with Current Injection (MAT-CI) is a new biological electrical impedance imaging technique that combines Electrical Impedance Tomography (EIT) with Ultrasonic Imaging (UI), which possesses the non-invasive and high-contrast of the EIT and the high-resolution of the UI. The MAT-CI is expected to acquire high quality image and embraces a wide application. Its principle is to put the conductive sample in the Static Magnetic Field(SMF) and inject a time-varying current, during which the SMF and the current interact and generate the Lorentz Force that inspire ultrasonic signal received by the ultrasonic transducers positioned around the sample. And then according to related reconstruction algorithm and ultrasonic signal, electrical conductivity image is obtained. In this paper, a forward problem mathematical model of the MAT-CI has been set up to deduce the theoretical equation of the electromagnetic field and solve the sound source distribution by Green’s function. Secondly, a sound field restoration by Wiener filtering and reconstruction of current density by time-rotating method have deduced the Laplace’s equation that caters to the current density to further acquire the electrical conductivity distribution image of the sample through iteration method. In the end, double-loop coils experiments have been conducted to verify its feasibility.

经颅磁声电刺激强度对小鼠前额叶皮质网络可塑性的影响

背景:经颅磁声电刺激是一种新型无创的神经调控技术,利用超声波与静磁场耦合作用产生的感应电场调节神经系统的放电活动,但其影响大脑突触可塑性的作用机制研究尚浅。目的:探讨经颅磁声电刺激强度对小鼠前额叶皮质神经网络突触可塑性的影响。方法:①动物实验:将24只C57小鼠平均且随机分为4组,对照组(接受伪刺激)、刺激6.35 W/cm^(2)组(接受0.3 T、6.35 W/cm^(2)的耦合刺激)、刺激17.36 W/cm^(2)组(接受0.3 T、17.36 W/cm^(2)组的耦合刺激)和刺激56.25 W/cm^(2)组(接受0.3 T、56.25 W/cm2的耦合刺激),记录小鼠执行T迷宫过程中局部场电位信号和行为学正确率。②建模仿真实验:构建经颅磁声电刺激小鼠前额叶皮质神经网络模型,分别比较不同刺激强度下神经网络结构连接特性。结果与结论:①经颅磁声电刺激能够有效缩短小鼠行为学习时间,工作记忆能力得到改善(P<0.05),且习得行为后继续刺激小鼠前额叶,各组小鼠T迷宫行为学实验准确度没有明显差异(P>0.1)。分析小鼠前额叶局部场电位信号发现经颅磁声电刺激促进了β节律与γ节律能量增强;而随刺激强度升高,β节律与γ节律出现了非同步性下降;通过β-γ相位幅值耦合发现,刺激增强了神经网络适应新的信息和任务要求的能力变化。②建模仿真发现,刺激使得神经网络放电水平增强,长时程突触权重水平提高而短时程突触权重仅在刺激强度较高时降低。③研究结果表明,不同的刺激强度与神经网络功能结构的影响存在复杂的非线性关系;这种神经调控技术为治疗突触功能障碍和神经网络异常等相关神经疾病方面提供新的可能。

A seafloor electromagnetic receiver for marine magnetotellurics and marine controlled-source electromagnetic sounding

In planning and executing marine controlled-source electromagnetic methods, seafloor electromagnetic receivers must overcome the problems of noise, clock drift, and power consumption. To design a receiver that performs well and overcomes the abovementioned problems, we performed forward modeling of the E-field abnormal response and established the receiver＇s characteristics. We describe the design optimization and the properties of each component, that is, low-noise induction coil sensor, low-noise Ag/AgCI electrode, low-noise chopper amplifier, digital temperature-compensated crystal oscillator module, acoustic telemetry modem, and burn wire system. Finally, we discuss the results of onshore and offshore field tests to show the effectiveness of the developed seafloor electromagnetic receiver and its performance： typical E-field noise of 0.12 nV/m/rt（Hz） at 0.5 Hz, dynamic range higher than 120 dB, clock drift lower than 1 ms/day, and continuous operation of at least 21 days.

经颅磁声电刺激对健康与帕金森病大鼠神经回路中beta振荡的影响

背景:经颅磁声电刺激是一种基于磁声耦合电效应的无创、高精度脑神经聚焦刺激方法,可调节神经节律振荡活动,从而影响大脑的运动、认知等功能。目的:探究经颅磁声电刺激对健康与帕金森病大鼠神经回路中beta振荡的影响。方法:①动物实验:采用随机数字表法将24只Wistar大鼠随机分为4组,每组6只:正常对照组不进行任何干预;正常刺激组大脑前额叶皮质接受经颅磁声电刺激(空间峰值脉冲平均强度为13.33 W/cm^(2),基波频率为0.4 MHz,基波周期数为1000,脉冲重复频率为200 Hz);模型对照组、模型刺激组通过腹腔注射1-甲基-4-苯基-1,2,3,6-四氢吡啶建立帕金森病模型,造模成功后,模型对照组大脑前额叶皮质接受经颅磁声电假刺激,模型刺激组大脑前额叶皮质接受经颅磁声电刺激,每天刺激时长2.0 min,刺激结束停留8-10 min后,采集大鼠执行T迷宫过程中局部场电位信号并同时记录行为学正确率,对比分析各组局部场电位信号能量的时频分布情况和行为差异,当大鼠正确率连续3 d高于80%后停止刺激实验和T迷宫实验。②建模仿真实验:构建经颅磁声电刺激下皮质-基底神经节回路模型,分别改变超声发射周期(5,10,20 ms)、超声发射占空比(30%,50%,90%)和感应电流密度(20,50,100μA/cm^(2)),比较不同刺激参数下健康与帕金森病大鼠beta振荡的功率谱密度值。结果与结论:①动物实验:正常对照组大鼠的空间学习能力强于模型对照组(P<0.001),正常刺激组大鼠的空间学习能力强于正常对照组(P<0.05),模型刺激组大鼠的空间学习能力强于模型对照组(P<0.01);正常对照组beta振荡能量分布较为集中,正常刺激组较正常对照组beta振荡信号能量有所降低,模型对照组与模型刺激组beta振荡能量广泛分布且能量值显著高于正常对照组、正常刺激组,并且模型刺激组beta振荡信号能量明显低于模型对照组;②建模仿真实验:不加刺激时,健康大鼠beta频段功率谱密度峰值(30 dB)显著低于帕金森病大鼠(55 dB);施加经颅磁声电刺激后,两组大鼠beta频段功率谱密度值普遍降低;beta频段功率谱密度峰值与超声发射周期呈正相关、与感应电流密度呈负相关,当超声发射占空比为50%时功率谱密度峰值最低;③结果表明:经颅磁声电刺激可抑制健康与帕金森病大鼠的beta振荡,进而改善大鼠的运动功能与决策认知功能。

电能高效高质转化技术与创新

电能转化是将电能转化为电能、磁能、热能、声能、光能等其他能量形式,是能源消费的核心基础,已渗透至经济发展和国防建设各个领域。电能高效高质转化技术作为绿色化、精细化能源消费革命的主体与核心技术,是国民经济和国防系统发展的基础、核心竞争力和综合实力的关键标志之一,也是国防和工业领域的“供能心脏”,对于推动我国能源低碳革命意义重大。我国电能转化技术与装备已取得了世界瞩目的成果,但仍存在工业电耗较高、装备卡脖子、国防有短板、基础研究薄弱等问题。为此,结合当前主要能源消费形式,重点梳理电能到电能、磁能、热能、声能、光能5种电能转化形式的基本原理、关键技术及发展现状,总结电能高效高质转换面临的难题及其发展对策,期望能够为我国电能转化技术与装备的发展提供一定参考。

电动汽车座舱内部噪声的非线性心理声学烦恼度建模

拟研究电动汽车座舱内部噪声特性对声学舒适性的影响。通过道路试验获取4种典型路面工况下某型电动汽车在不同车速下的舱内噪声,计算分析其心理声学参数,开展烦恼度主观评价实验,并基于非线性Zwicker心理声学烦恼度及其修正模型进行建模研究。结果显示,随着车速和路面粗糙程度变大,响度逐渐提高,尖锐度也随车速增大而变大;Zwicker心理声学烦恼度模型更适用于电动汽车座舱内部噪声。

基于声电类比的低频消音结构优化设计

基于声电类比,设计了与电滤波器性能相似的低频消音结构,并结合传递矩阵法和模拟退火法,构造了声学结构的优化设计策略。首先,采用归一化方法,以四阶切比雪夫高通电滤波器为基准,设计了电学带阻滤波器;然后,基于声电类比,将电路中的电感电容转换为声学结构中的细管和圆柱腔,构造了消音结构原型,并利用传递矩阵法,建立其数学模型,推导声波传递损失表达式;最后,结合声学结构的数学模型和模拟退火法,以有效衰减带宽最大为目标,以消音结构的尺寸参数为变量,对原型结构进行优化设计。结果表明:基于声电类比,能获得合理的消音结构原型,克服了仅依靠经典消音结构进行设计的局限;结合推导的传递损失数学模型和模拟退火法,对消音结构原型进行参数优化,能显著提高其消音效果,表现在传递损失超过20 dB的带宽拓宽至410~2 165 Hz,是优化前带宽的202%,特别是优化后的结构克服了原型结构在466~537 Hz频率内不能实现有效消音的缺陷,获得了连续的大跨度有效带宽,且传递损失曲线平均增幅达22.8%。

聚丙烯腈纳米纤维基压电声学传感器的制备及性能

为提高柔性声学传感器的声电转换能力,采用静电纺丝技术制备不同纺丝液浓度和不同厚度的聚丙烯腈(PAN)纳米纤维膜,构筑“三明治”结构柔性声学传感器。研究了纺丝液浓度和纤维膜厚度对膜谐振特性和声学传感器输出电压的影响,以及薄膜谐振特性与传感器输出电压响应之间的关联性。结果表明,纺丝液浓度直接影响分子链构象、纤维直径及其均匀度;其中构象会影响薄膜的压电性能和声学传感器的声电转换过程、纤维直径和均匀度会影响膜的谐振特性,从而影响器件的输出电压。当纺丝液浓度为12%、PAN纳米纤维膜厚度为60μm时,构筑的声学传感器的输出电压最高可达2.7 V。

基于多物理场复合的新型无创脑深部精准刺激方法探究

现有的无创电磁刺激技术,以临床应用最广的经颅磁刺激(TMS)为代表,尚无法突破聚焦性和刺激深度的技术瓶颈,实现对深部功能核团的直接精准刺激。本研究基于磁声耦合理论,结合TMS技术中的交变磁场,提出一种新的基于多物理场复合的无创脑深部精准刺激方法(MI-TMAS),以期实现对脑深部的直接精准聚焦刺激。基于磁声耦合理论和磁感应理论对MI-TMAS中的刺激物理场进行仿真研究,并搭建了MI-TMAS系统及多物理场测试平台,对刺激物理场分布并进行实测。结合仿真和实测结果,对MI-TMAS复合刺激电场的聚焦性和电场强度进行探究。结果显示,该方法能够在脑深部靶区产生聚焦声场、磁声耦合电场、磁感应电场等3个复合刺激物理场,可以在刺激深度50 mm处形成聚焦尺寸约6.2 mm(-3 dB)的复合刺激电场,其在脑深部电场的聚焦性明显优于TMS,且刺激电场强度大于稳恒磁场下的TMAS。本研究为MI-TMAS方法应用于在体神经调控提供了理论以及技术基础。

巴特沃斯带阻声学滤波器设计

基于声电类比,通过电滤波器设计声学结构,得到的声学结构和电滤波器的滤波性能存在差异。为此,提出了针对声学结构声质量和声容的修正策略。首先,基于声电类比,建立声学滤波器的理论传递函数模型。然后,设计一阶巴特沃斯带阻声学滤波器,应用有限元法仿真其传递损失,并与传递函数理论模型的计算结果进行比较。接着,采用最小二乘法构造迭代优化算法,基于有限元幅频仿真数据,拟合声学滤波器的传递函数,计算声质量和声容的理论值和拟合值之间的误差,提出声质量和声容的修正策略。最后,通过设计一阶和三阶巴特沃斯声学带阻滤波器,对修正策略进行验证。研究表明,基于声电类比设计的声学滤波器,中心频率和阻带宽度皆偏离设计目标,且相对误差随目标阻带宽度的增加而增加;修正后的一阶巴特沃斯声学带阻滤波器,中心频率和阻带宽度的相对误差均值皆小于2%;修正后的三阶巴特沃斯声学带阻滤波器,中心频率相对误差从4.6%降到0.6%,阻带宽度相对误差从7.5%降到2.5%;应用提出的声质量和声容的修正策略,能显著提高通过电滤波器预测声学结构滤波性能的精度。

基于磁声耦合效应的电导率重建方法研究综述

介绍了基于磁声耦合效应的磁声层析成像(magneto-acoustic tomography,MAT)和磁声电层析成像(magneto-acousto-electrical tomography,MAET)2类电导率成像方法的正问题与逆问题的理论基础,综述了不同成像策略的电导率重建方法的研究进展,分析了基于磁声耦合效应的电导率重建方法在声源模型构建、重建算法和成像速度等方面存在的问题,并展望了未来的发展方向。

掘进工作面煤岩动力灾害声电响应特征

为了监测、预警掘进过程中前方可能发生的危险,在掘进工作面布设声电监测预警系统,利用声发射技术和电磁辐射技术对掘进巷道进行动态实时监测和预警,通过对掘进过程中异常声电响应特征的研究得到突出危险发生的前兆规律特征,并根据现场实际情况进行了验证。结果表明,掘进过程中,声发射、电磁辐射强度整体变化趋势呈现3个阶段;煤与瓦斯突出危险发生时,声电强度参数响应剧烈,出现了明显的声增电降趋势,且声发射、电磁辐射强度与瓦斯浓度呈显著相关,瓦斯浓度突增与声电信号异常基本是同步发生的;声—电—瓦斯能够反映煤岩石动力演化过程中的变化情况,可将第一次声电异常波动定为瓦斯预警前兆开始时间,超前预警8 h左右。由此可以看出,通过研究声—电—瓦斯的异常响应,能够实现煤与瓦斯突出的预警预报。

动车组头车声固耦合模态分析及多目标优化

目前针对高速列车领域声固耦合共振现象的产生机理和影响因素尚缺乏深入探讨,并且基于声固耦合共振理论的车体优化设计也需进一步开展。该研究基于模态等效和质量等效原则建立动车组头车有限元模型,分别进行结构模态、声场模态和考虑内外声场影响的声固耦合模态分析。分析结果表明:结构模态频率符合头车设计规范;声场模态存在与结构模态相近的特征频率,为后续耦合共振优化提供依据;内外声场的耦合作用导致结构和声场系统的模态参数变化,论证了模态分析中考虑声固耦合因素的必要性。基于模态分析结果,对动车组头车结构进行了两项优化设计:以车体质量最小化为目标,车身厚度为设计变量,在满足一阶垂弯模态频率约束条件下进行车体减重设计;为避免耦合共振影响,提取结构和声场固有频率值接近的模态阶次,将二者的频率差最大化作为优化目标,引入车体减重设计模型,形成头车轻量化与舒适性指标同步提升的多目标优化体系。