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2014 IEEE International Ultrasonics Symposium最新文献

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Impact of composition and structure of Al alloy electrodes to power durability of SAW devices 铝合金电极组成和结构对SAW器件功率耐久性的影响
Pub Date : 2014-10-23 DOI: 10.1109/ULTSYM.2014.0218
R. Takayama, H. Nakanishi, K. Hashimoto
This paper reviews power durability of SAW filters in terms of its dependence on temperature and input power, and discusses how composition and structure of Al alloy electrodes affect power durability. First, the time to fail (TF) measurement is discussed. It is shown that change of the frequency response must be taken into account for the acceleration test. This is because excess temperature causes shift of the passband. Difference of the chip temperature with the environment must be also considered. Two types of four layer electrodes (AlMgCu/Ti/AlMgCu/Ti and AlScCu/Ti/AlScCu/Ti) are used for the discussion. Series of power durability tests are performed for 800 MHz and 1.9 GHz SAW devices, and we reveal how choice of the additives, their content and layer thicknesses influence behavior of the Al migration and affect the TF performances.
本文综述了SAW滤波器的功率耐久性对温度和输入功率的依赖关系,并讨论了铝合金电极成分和结构对功率耐久性的影响。首先,讨论了失效时间(TF)的测量。结果表明,加速度试验必须考虑频率响应的变化。这是因为温度过高会引起通带的移位。还必须考虑芯片温度与环境的差异。本文讨论了两种四层电极(AlMgCu/Ti/AlMgCu/Ti和AlScCu/Ti/AlScCu/Ti)。在800 MHz和1.9 GHz SAW器件上进行了一系列的功率耐久性试验,揭示了添加剂的选择、含量和层厚度对Al迁移行为和TF性能的影响。
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引用次数: 12
Ultrasound contrast plane wave imaging with higher CTR based on pulse inversion bubble wavelet transform 基于脉冲逆泡小波变换的高CTR超声对比平面波成像
Pub Date : 2014-10-23 DOI: 10.1109/ULTSYM.2014.0437
Diya Wang, Xuan Yang, J. Wan, Bowen Jing, Lei Zhang, M. Wan
Although ultrasound contrast plane wave imaging can avoid the repeated disruption and capture the transient spatial distribution of microbubbles, it is still limited by lower contrast-to-tissue ratio (CTR) due to low negative peak pressure and lacks of transmit focus. The purpose of this paper was to develop an ultrasound contrast plane wave imaging method combined with pulse inversion bubble wavelet transform imaging (PIWI) technique to improve the CTR of plane wave images. First, a pair of “bubble wavelets” was constructed by microbubbles scattering echoes predicted by modified Herring equation driven by two inverted plane waves. Next, the original echoes from such plane waves were performed by bubble wavelet correlation analysis. Then, such echoes replaced by the maximal wavelet correlation coefficients were summed to distinguish echoes of microbubbles and tissues. In vivo rabbit kidney experiments, the CTR of plane wave imaging was improved to 15.19 dB by PIWI technique without the sacrifice of image frame, which was larger 4.48±0.96 dB than that of raw images. In summary, this method could contribute to plane wave imaging by allowing the continuous transient monitoring of the accumulation of microbubbles with higher CTR.
超声对比平面波成像虽然可以避免重复破坏,捕捉微泡的瞬态空间分布,但由于负峰压低,缺乏透射焦点,仍然受到较低的组织对比比(CTR)的限制。本文的目的是开发一种结合脉冲逆泡小波变换成像(PIWI)技术的超声平面波成像方法,以提高平面波图像的CTR。首先,利用修正的Herring方程预测由两个倒平面波驱动的微气泡散射回波,构建了一对“气泡小波”;然后对平面波的原始回波进行泡小波相关分析。然后用最大小波相关系数代替这些回波进行求和,区分微泡和组织的回波。在兔肾活体实验中,在不牺牲图像帧的情况下,PIWI技术将平面波成像的CTR提高到15.19 dB,比原始图像提高4.48±0.96 dB。总之,该方法可以实现平面波成像,允许对微泡积累进行连续的瞬态监测,具有较高的CTR。
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引用次数: 7
Balanced wide band fan-shaped three-tranducer SAW filters with reduced insertion loss and improved frequency response 平衡宽带扇形三换能器SAW滤波器,降低了插入损耗,改善了频率响应
Pub Date : 2014-10-23 DOI: 10.1109/ULTSYM.2014.0505
S. Doberstein
This paper presents the new balanced SAW filters using fan-shaped IDTs with reduced insertion loss, a fractional bandwidth of 10-24% on 128°YX LiNbO3. The fan-shaped three-transducer structure containing one input IDT and two output IDTs with the split electrodes is used in these filters. The constructional and topological optimization of the SAW filters is provided with a computer simulation using an δ-function model. The 255, 305 MHz samples of the SAW filters have shown 3-dB bandwidth of 30-61 MHz, insertion loss of 5.5-7.5 dB, passband ripple of around 3 dB, shape factor of 1.28-1.5, stopband attenuation over 40 dB in a matched system. The samples were housed in the 5×5×1.35 mm SMD packages and could operate in balanced/unbalanced 50-Ω system.
本文介绍了采用扇形idt的新型平衡SAW滤波器,在128°YX LiNbO3上降低了插入损耗,分数带宽为10-24%。这些滤波器采用扇形三换能器结构,其中包含一个输入IDT和两个带分裂电极的输出IDT。利用δ函数模型对声表面波滤波器的结构和拓扑进行了计算机仿真。在255、305 MHz采样下,SAW滤波器的3-dB带宽为30-61 MHz,插入损耗为5.5-7.5 dB,通带纹波约为3 dB,形状因子为1.28-1.5,阻带衰减超过40 dB。样品被安置在5×5×1.35 mm SMD封装中,可以在平衡/不平衡50-Ω系统中运行。
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引用次数: 2
New performance metrics for ultrasound pulse compression systems 超声脉冲压缩系统的新性能指标
Pub Date : 2014-10-23 DOI: 10.1109/ULTSYM.2014.0109
S. Harput, J. Mclaughlan, D. Cowell, S. Freear
In medical ultrasound, B-mode images are log-compressed and displayed with a grayscale map, typically on a 40-60 dB dynamic range. The image formation process is the same for an ultrasound pulse compression system using coded excitation. Metrics, such as full width at half maximum (FWHM), peak sidelobe level (PSL) and integrated sidelobe level (ISL), used to evaluate pulse compression systems were adopted from radar and communications. These metrics are utilized to evaluate the performance of an auto-correlation function, which is the ideal case. In medical ultrasound imaging however, the combination of frequency and depth dependent attenuation, dispersion, harmonic generation, beamforming errors, and limited transducer bandwidth create a more complicated case for a pulse compressed system that is far from the ideal.
在医学超声中,b模式图像被对数压缩,并以灰度图显示,通常在40-60 dB动态范围内。图像的形成过程是相同的超声脉冲压缩系统使用编码激励。在雷达和通信领域,采用半最大全宽(FWHM)、峰值旁瓣电平(PSL)和综合旁瓣电平(ISL)等指标来评价脉冲压缩系统。这些指标用于评估自相关函数的性能,这是理想的情况。然而,在医学超声成像中,频率和深度相关的衰减、色散、谐波产生、波束形成误差和有限的换能器带宽的结合,使脉冲压缩系统的情况更加复杂,远远不是理想的。
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引用次数: 24
Effects of viscous liquid on SH wave propagation in layered viscoelastic/piezoelectric structure 黏性液体对层状粘弹性/压电结构中SH波传播的影响
Pub Date : 2014-10-23 DOI: 10.1109/ULTSYM.2014.0490
Jing Cui, Jianke Du, Ji Wang
An analytical approach is taken to investigate SH wave propagation in a layered viscoelastic/piezoelectric structure loaded with nonconductive liquid. The interface between the viscoelastic layer and the piezoelectric substrate is perfect. The dispersion relations are obtained for electrically shorted and open case, respectively. The effects of the dynamic viscous coefficient of the liquid on the phase velocity and the attenuation are figured and presented.
采用解析方法研究了含非导电液体的层状粘弹性/压电结构中SH波的传播。粘弹性层与压电基板之间的界面良好。分别得到了电短路和开路情况下的色散关系。给出了流体的动态粘滞系数对相速度和衰减的影响。
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引用次数: 4
Signal optimization of PSK modulated gold-sequences for narrow band transducers 窄带换能器中PSK调制金序列的信号优化
Pub Date : 2014-10-23 DOI: 10.1109/ULTSYM.2014.0136
Andreas Schroder, B. Henning
Code division multiple access is a well-known method to minimize crosstalk between unsynchronized ultrasonic distance sensors. Thereby orthogonal signals are used which are generated by modulating orthogonal codes to a carrier signal. In this contribution PSK modulation is used to transmit gold sequences. Here narrow band air ultrasound transducers are used. Due to the limited bandwidth of the transducer there is a partial cross correlation between the electrical received signals. This can increase the error rate identifying the signals. By optimizing the modulation parameters the error rate can be reduced. Therefore the influence of an offset of the carrier frequency for different symbol lengths to the properties of the electrical received signals is investigated.
码分多址是一种众所周知的减少非同步超声距离传感器间串扰的方法。因此,使用通过将正交编码调制为载波信号而产生的正交信号。在这个贡献中,PSK调制被用来传输金序列。这里使用窄带空气超声换能器。由于换能器的带宽有限,接收到的电信号之间存在部分互相关。这会增加识别信号的错误率。通过优化调制参数可以降低误码率。因此,研究了不同符号长度的载波频率偏移对接收电信号特性的影响。
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引用次数: 4
Optimization of free-moving elements in 2D ultrasound sparse arrays 二维超声稀疏阵列中自由运动单元的优化
Pub Date : 2014-10-23 DOI: 10.1109/ULTSYM.2014.0545
B. Diarra, M. Robini, Emmanuel Roux, H. Liebgott, C. Cachard, P. Tortoli
The non-grid sparse array technique is a promising approach to overcome the connection difficulties of 2D matrix arrays and to partially compensate the energy loss linked to the element number reduction. Being independent from the spatial sampling conditions, this method leads to a significant improvement of the beam pattern when combined to the simulated annealing algorithm. However, in the previous version of this method, the position of the elements cannot be changed during the optimization. In order to add a further degree of freedom and thus to improve the optimization performance, we propose a new strategy in which both element position and apodization can be modified. This new approach improves the sensitivity thanks to a better distribution of the elements on the array footprint.
非网格稀疏阵列技术是克服二维矩阵阵列连接困难和部分补偿单元数减少带来的能量损失的一种很有前途的方法。该方法不依赖于空间采样条件,与模拟退火算法相结合,可以显著改善光束方向图。但是,在该方法的上一个版本中,在优化过程中不能改变元素的位置。为了进一步增加自由度,从而提高优化性能,我们提出了一种元件位置和apodiization都可以修改的新策略。这种新方法由于更好地分布了阵列上的元素,从而提高了灵敏度。
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引用次数: 2
Compressive-sensing like grating-lobe suppressed image reconstruction for photoacoustic linear array imaging 基于压缩传感的光声线阵成像光栅瓣抑制图像重建
Pub Date : 2014-10-23 DOI: 10.1109/ULTSYM.2014.0315
Chien-Hao Chiu, Meng-Lin Li
To avoid large grating lobes, using a small element-to-element pitch of ultrasound array transducers for photoacoustic (PA) imaging is necessary. Such constraint introduces higher system cost and complexity, especially when greater than 20-MHz high-frequency arrays are used. As a result, to reduce fabrication difficulties and obtain better signal sensitivity in PA imaging, ultrasound linear array transducers are commonly used in practice instead of phased arrays. However, the field-of-view (FOV) is limited to the full aperture size because linear arrays do not have the ability to steer PA receive beams without the introduction of large grating lobes. In addition, strong PA signals are commonly generated in the near field in the back-ward mode where grating-lobe clutters can even hamper the image contrast seriously. In this study, we proposed a novel compressed-sensing-like grating-lobe suppressed image reconstruction method for PA linear array imaging. To overcome the tradeoff between FOV and grating lobe clutters introduced by using a linear array, compressive sensing (CS) concept is adopted here to reduce the grating lobes. The CS theory relies on an important principle: sparsity. Fortunately, unlike ultrasound imaging, absorption distribution in PA imaging intrinsically owns sparsity in the spatial domain. In consequence, a sparsity constraint minimizing the L1 norm of energy deposition can be introduced to the conventional reconstruction method. By adopting such a constraint and using the nonlinear recovery algorithm based on convex optimization, PA linear array imaging can be reconstructed with grating lobe clutters greatly suppressed. Simulation results demonstrated that the proposed method can reduce the grating lobes caused by using a linear array with large FOV. In the meantime, compared with the image reconstructed by the traditional back-projection method, the image reconstructed by the proposed method has fewer artifacts.
为了避免大的光栅瓣,使用小的元间距超声阵列换能器进行光声成像是必要的。这种限制带来了更高的系统成本和复杂性,特别是当使用大于20 mhz的高频阵列时。因此,为了降低制作难度并在PA成像中获得更好的信号灵敏度,在实践中通常使用超声线阵换能器来代替相控阵换能器。然而,视场(FOV)仅限于全孔径大小,因为线性阵列没有能力在没有引入大光栅瓣的情况下引导PA接收光束。此外,在反向模式下,近场通常会产生较强的扩音信号,其中光栅瓣杂波甚至会严重影响图像对比度。在这项研究中,我们提出了一种新的类似压缩传感的光栅瓣抑制图像重建方法。为了克服线性阵列在视场和光栅瓣杂波之间的权衡,本文采用压缩感知(CS)的概念来减小光栅瓣杂波。CS理论依赖于一个重要的原则:稀疏性。幸运的是,与超声成像不同,PA成像的吸收分布在空间域上具有固有的稀疏性。因此,可以在传统的重建方法中引入最小化能量沉积L1范数的稀疏性约束。采用这一约束条件,采用基于凸优化的非线性恢复算法,可以在很大程度上抑制光栅瓣杂波的情况下重建光栅线阵成像。仿真结果表明,该方法可以有效地减小视场大的线阵所产生的光栅瓣。同时,与传统的反投影方法重建的图像相比,该方法重建的图像具有较少的伪影。
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引用次数: 2
Surface acoustic wave scattering by substrate edges 基材边缘对表面声波的散射
Pub Date : 2014-10-23 DOI: 10.1109/ULTSYM.2014.0512
A. Darinskii, M. Weihnacht, H. Schmidt
The harmonic surface acoustic wave (SAW) scattering at 90-degree corners of piezoelectric substrates is studied by FEM. The SAW is incident perpendicular to the vertical border. The dependences of the reflection and transmission coefficients on the radius of the fillet at the corner are found for 128°YX and YZ LiNbO3 as well as ST-X quartz substrates. It is demonstrated that if the substrate is anisotropic, then a SAW can be scattered off differently at the right-hand border and the left-hand border. Computations for YZ LiNbO3 illustrate possible levels of the anisotropy of the scattering for mutually reverse directions of incidence. However, if the substrate is oriented in a specific manner, then the scattering from the right-hand border is identical to the scattering from the left-hand border. There are four types of such orientations.
采用有限元法研究了压电基板90度角处谐波表面声波的散射特性。SAW垂直于垂直边界入射。对于128°YX和YZ LiNbO3以及ST-X石英衬底,反射系数和透射系数对角角圆角半径的依赖关系被发现。结果表明,如果衬底是各向异性的,那么声表面波在左、右边界的散射是不同的。对YZ LiNbO3的计算说明了相互反向入射方向散射的各向异性的可能水平。然而,如果基材以特定的方式定向,则来自右边界的散射与来自左边界的散射相同。这种定向有四种类型。
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引用次数: 0
Non-invasive strain imaging in normotensive and hypertensive patients 无创应变成像在正常血压和高血压患者中的应用
Pub Date : 2014-10-23 DOI: 10.1109/ULTSYM.2014.0448
R. W. Boekhoven, L. Marais, M. Rutten, F. N. v.d. Vosse, P. Boutouyrie, R. Lopata
Literature shows that arterial stiffness is related to age and degree of atherosclerosis. It has been hypothesized that there is no difference in arterial stiffness between normotensive (NT) and hypertensive (HT) patients of same sex and age. This was demonstrated in a previous study by analysing pressure diameter curve data and estimating the incremental Youngs modulus [1]. In this study, 2D strain imaging was used to investigate possible differences in carotid stiffness by quantifying the response to pressure, i.e., strain, in a group of NT and HT subjects, matched for both age and sex. Radio-frequency data of the common carotid artery were acquired in 18 NT and 18 HT patients, with a mean age of 52 ± 11, using the Mylab 70 (Esaote, NL). Displacements and strains were estimated using a 2D strain imaging algorithm [2]. Strain analysis was performed and on the far wall data at end-systole. One-way ANOVA indicates significant lower strains in the HT groups throughout the vessel wall (NT = 6.3%±5.6%; HT = 4.8%±3.9%). The lower strain and distensibility can be explained by the higher mean arterial pressure and non-linear behaviour of the vascular tissue. These results confirm the hypothesis that the stiffness in HT patients is not necessarily higher compared to NT patients.
文献显示,动脉硬度与年龄和动脉粥样硬化程度有关。据推测,相同性别和年龄的正常血压(NT)和高血压(HT)患者的动脉硬度没有差异。之前的研究通过分析压力直径曲线数据和估算增量杨氏模量证明了这一点[1]。在这项研究中,通过量化一组年龄和性别匹配的NT和HT受试者对压力(即应变)的反应,使用二维应变成像来研究颈动脉僵硬度可能存在的差异。使用Mylab 70 (Esaote, NL)获取18例NT和18例HT患者颈总动脉的射频数据,平均年龄为52±11岁。使用二维应变成像算法估计位移和应变[2]。对收缩期末远壁数据进行应变分析。单因素方差分析显示,HT组在整个血管壁的菌株显著降低(NT = 6.3%±5.6%;Ht = 4.8%±3.9%)。较低的应变和膨胀性可以用较高的平均动脉压和血管组织的非线性行为来解释。这些结果证实了HT患者的僵硬度并不一定比NT患者高的假设。
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引用次数: 0
期刊
2014 IEEE International Ultrasonics Symposium
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