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用声传递函数确定骨组织的特性 总被引:1,自引:0,他引:1
用双加速度计在体和离体测试了骨组织的声传递函数。结果表明:骨组织具有声低通滤波特性,且可产生多种振动模式。声传递函数的特征因人而有较大差异,但同一对象左右两肢的测试结果可以对照。声传递函数的主频能很好地反映骨的缺陷大小,可用于诊断骨病和估计骨折愈合程度。 相似文献
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1 Introduction Opticaltomographyofscatteringmediasuchasbiologicaltissuesisanincreasinglyactivefieldbecauseofitsadvantagesinnoninvasion ,nonionizationandopticalcontrastwhenitisusedforbiomedicaldiagnosis[1] .Themechanismofopticalimagingisbasedonthediffere… 相似文献
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Identification of denatured and normal biological tissues based on compressed sensing and refined composite multi-scale fuzzy entropy during high intensity focused ultrasound treatment 下载免费PDF全文
In high intensity focused ultrasound(HIFU)treatment,it is crucial to accurately identify denatured and normal biological tissues.In this paper,a novel method based on compressed sensing(CS)and refined composite multi-scale fuzzy entropy(RCMFE)is proposed.First,CS is used to denoise the HIFU echo signals.Then the multi-scale fuzzy entropy(MFE)and RCMFE of the denoised HIFU echo signals are calculated.This study analyzed 90 cases of HIFU echo signals,including 45 cases in normal status and 45 cases in denatured status,and the results show that although both MFE and RCMFE can be used to identify denatured tissues,the intra-class distance of RCMFE on each scale factor is smaller than MFE,and the inter-class distance is larger than MFE.Compared with MFE,RCMFE can calculate the complexity of the signal more accurately and improve the stability,compactness,and separability.When RCMFE is selected as the characteristic parameter,the RCMFE difference between denatured and normal biological tissues is more evident than that of MFE,which helps doctors evaluate the treatment effect more accurately.When the scale factor is selected as 16,the best distinguishing effect can be obtained. 相似文献
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In this Letter, we have shown that a giant Goos–H?nchen shift of a light beam reflected at terahertz frequencies can be achieved by using a composite structure, where monolayer graphene is coated on one-dimensional photonic crystals separated by a dielectric slab. This giant Goos–H?nchen shift originates from the enhancement of the electrical field, owing to the excitation of optical Tamm states at the interface between the graphene and onedimensional photonic crystal. It is shown that the Goos–H?nchen shift in this structure can be significantly enlarged negatively and can be switched from negative to positive due to the tunability of graphene's conductivity. Moreover, the Goos–H?nchen shift of the proposed structure is sensitive to the relaxation time of graphene and the thickness of the top layer, making this structure a good candidate for a dynamic tunable optical shift device in the terahertz regime. 相似文献
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引入负声源,导出了环形平面换能器声场的简洁表示式,计算了单个圆环、多个同心圆环同时激励及环阵相控聚焦声源产生的声场,分析了环的宽度、环数及聚焦点位置等因素对声场特征的影响。提出根据各阵元在声场中某点产生的声压的相位来确定各阵元电激励信号的延时,此方法较根据各阵元到该点的平均声程确定各阵元电激励信号的延时,能更难确地在该点实现聚焦。 相似文献
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高强度聚焦超声用于肿瘤治疗的研究 总被引:2,自引:0,他引:2
高强度聚焦超声(HIFU)能在短时间内使病变组织的温度升至70℃以上,导致病变组织凝固坏死,是一种具有巨大潜力的、非侵入的、有效的肿瘤治疗手段。本文对HIFU的动物试验、临床应用及治疗装置的研究情况进行了总结,分析了该技术尚存在的问题,最后展望了其应用前景。 相似文献