共查询到20条相似文献,搜索用时 212 毫秒
1.
针刺内关穴对心律失常病人脉象频域特性的影响 总被引:1,自引:0,他引:1
目的研究针刺内关穴对心律失常病人脉象频域特性的影响。方法以15例临床心律失常病人为研究对象,使用自主设计的针刺仪与脉象仪,检测针刺内关穴前后的脉象图以及针刺过程中针体受力数据,采用粗粒谱法对脉象数据进行频域分析,以所得功率谱中主频幅值P1与次主频幅值P2的比值作为特征参数,比较针刺前后此特征参数的变化。结果针刺前后脉象功率谱的特征参数发生显著性改变(P<0.05)。结论针刺内关穴使心血管系统获得优化方向的调节,从而有利于心率失常患者的心功能康复。 相似文献
2.
目的设计一套在体实时监测针刺针体受力情况和同步观察针刺前后脉象的系统。方法利用设计的针刺测力仪及脉象仪采集针刺时针体受力的力学信号及人体脉象的信号并将这些信号传换成计算机能识别的信号,把脉象的信号与针刺信号相对应运用软件进行分析整理。结果针刺前后脉象有比较明显的变化。结论利用脉象仪和针刺测力仪能够观察针刺前后脉象的变化,将为针刺选穴,配穴及疗效监测提供有效的手段。 相似文献
3.
时域—频域结合分析法—一种分析果蝇求爱歌的新方法 总被引:3,自引:1,他引:2
我们设计了一种时域-频域结合分析法,并用此方法分析了6个种群12种果蝇的求爱歌,发现如果将时域与频域的研究结合起来,对求爱歌进行频谱分析,可以定量地揭示出求爱歌的频域特性及其在时域上的细微变化。我们还对果蝇求爱歌的时域模式进行了初步的探讨,发现它们是在同一基本成分上进行调制而产生的,亲缘关系较近的种具有相近的调制方式。在对杂交后代的求爱歌的频谱分析中,我们还发现频谱上的某些特点是能够遗传的。这一新的研究方法为果蝇的进化遗传学和神经遗传的研究提供了一种新的手段。 相似文献
4.
5.
6.
7.
棺头蟋属六种常见蟋蟀鸣声特征分析与种类鉴定(直翅目:蟋蟀总科) 总被引:3,自引:0,他引:3
本文对蟋蟀科Grylidae棺头蟋属Loxoblemmus6种常见种类的鸣声特征进行了较为系统的分析研究。从其频域特征和时域特征上明显地显示了种间差异,并将其鸣声特征用于分类。 相似文献
8.
棺头蟋属六种常见蟋蟀鸣声特征分析与种类鉴定 总被引:13,自引:2,他引:11
本文对蟋蟀科Gryllidae棺头蟋属Loxoblemmus6种常见种类的鸣声特征进行了较为系统的分析研究,从其频域特征和时域特征上明显地显示了种间差异,并将其鸣声特征用于分类。 相似文献
9.
采用探测器的脉冲响应在频域反卷积滤波光声信号以进一步提高光声成像的分辨率.由仿真和实验结果表明,频域反卷积滤波重建相对于时域反投影重建和滤波反投影重建具有更好的成像效果,明显地提高重建图像的分辨率,经仿真结果的计算,其重建图像的分辨率由2.58 mm提高到了0.16 mm.实验所用的光源为YAG激光器,波长为1064 ... 相似文献
10.
心音的时间序列分析和功率谱估计已有文献报道(1,2),但人们对心杂音的时域、频域特征则很少了解。关于心音的阻尼系数、残差等其它时域参数以及能量在频域内的分布情况亦未见报道。心音、心杂音是心脏、大血管振动时所产生。研究心音、心杂音,实际上是研究心脏和大血管的振动过程,其理论价值远远超出入耳心脏听诊和普通心音图记录对心音、心杂音的解释。但由于存在一些方法上的问题,分析结果不太令人满意,因而未被广泛应用于临床。本文从临床需要出发,根据心音、心杂音的形成机制,对其在时域、频域分析中的若干方法学问题和可 相似文献
11.
Dynamics of the head-neck complex in response to the trunk horizontal vibration: modeling and identification 总被引:3,自引:0,他引:3
Although many studies exist concerning the influence of seat vibration on the head in the seated human body, the dynamic response of the head-neck complex (HNC) to the trunk vibration has not been well investigated. Little quantitative knowledge exists about viscoelastic parameters of the neck. In this study, the dynamics of the HNC is identified when it is exposed to the trunk horizontal (fore-and-aft) vibration. The frequency response functions between the HNC angular velocity and the trunk horizontal acceleration, corresponding to four volunteers, are obtained in the frequency range of 0.5 Hz to 10 Hz. A fourth-order mathematical model, derived by considering a double-inverted-pendulum model for the HNC, is designed to simulate the dynamic response of the HNC to the trunk horizontal vibration. The frequency domain identification method is used to determine the coefficients of the mathematical model of the HNC. Good agreement has been obtained between experimental and simulation results. This indicates that the system, similar to the designed fourth-order model, has mainly two resonance frequencies. The viscoelastic parameters of the neck, including the spring and damping coefficients, are then obtained by use of the optimization method. 相似文献
12.
Wang SC 《Biosensors & bioelectronics》2004,20(1):139-142
Pulse field driven electro-separations have been used for different analytical advantages, such as signal quality improvement and separation performance improvement. We have studied the temporal electro-osmosis in microchannels due to viscous diffusivity under the external pulse electric fields. Theoretical studies derived from Navier-Stokes equations conclude the dependence of the time to steady state electro-osmosis on the channel sizes. Pulse field frequency should be limited by the electro-osmosis setting-in time. We also observed the unstable electro-osmosis as the external field frequency increases. As channel geometry characterization results are employed in the mathematical models, the threshold frequencies obtained in experimental data are consistent with the computational predictions. In previous studies, effective signal quality improvement of electro-separations has been demonstrated, when external pulse fields modulate analyte velocities with synchronous lock-in detection. The results indicate signal-to-noise ratio improvement would be more significant at the high frequency regime where flicker noise is not dominant. Since bandwidth limitation due to fluid viscosity constrains the pulse frequency, optimum analyte velocity modulation is in need of further investigation. Under the bandwidth constrains, we have investigated the theoretical optimum modulation frequencies. 相似文献
13.
We describe real time background suppression of autofluorescence from biological samples during frequency domain or phase modulation measurements of intensity decays. For these measurements the samples were excited with a train of light pulses with widths below 1 ps. The detector was gated off for a short time period of 10 to 40 ns during and shortly after the excitation pulse. The reference signal needed for the frequency domain measurement was provided by a long-lifetime reference fluorophore which continues to emit following the off-gating pulse. Both the sample and the reference were measured under identical optical and electronic conditions avoiding the need for correction of the photomultiplier tube signal for the gating sequence. We demonstrate frequency domain background suppression using a mixture of short- and long-lifetime probes and for a long-lifetime probe in human plasma with significant autofluorescence. 相似文献
14.
The dispersion law and collisionless damping rate of quasi-potential waves in the plasma formed upon tunnel ionization of gas atoms in the field of a short pulse of circularly or linearly polarized radiation are found. It is shown how the frequency and damping rate of quasi-potential waves depend on the wave propagation direction relative to the symmetry axis of the photoelectron distribution. It is established that, in plasma with a toroidal photoelectron velocity distribution, weakly damped waves with a linear dispersion law and frequency above the electron plasma frequency can propagate in a wide range of angles. In the case of a bi-Maxwellian photoelectron distribution, the frequency of weakly damped waves is comparable with the electron plasma frequency and the anisotropy of electron motion manifests itself in relatively small corrections to the dispersion law. 相似文献
15.
Ning Jiang Philip A. Parker Kevin B. Englehart 《Journal of electromyography and kinesiology》2009,19(4):e267-e279
The spectrum of nonstationary electromyographic signal (EMG) is investigated, from which the error for neural drive information estimation from nonstationary EMG is studied in terms of signal-to-noise ratio (SNR), in analytical, numerical simulation, and experimental work. The signal refers to the neural drive information embedded within the nonstationary EMG, and noise refers to other portions of EMG that induce error in the estimation. The analytical expressions for the SNRs of force-modulated EMG with both single and multiple motor units (MU) are derived based on a sinusoidal integral pulse frequency modulation (IPFM) model. It is shown that the previously developed SNR expressions for stationary (unmodulated) EMG are special cases of the formulas presented here. The SNR results obtained from numerical simulated EMG agree very well with the analytical result. Results from nonstationary (modulated) surface EMG obtained from seven subjects also match the analytical and simulation results reasonably well. The results obtained from this work establish an analytical framework in studying and estimating the neural drive information contained in the EMG in the context of anisotonic and isometric contractions. Through the analytical study, the effects of different physiological parameters are identified, thus providing theoretical guidelines for developing advanced signal processing methods for nonstationary EMG in applications such as prosthesis control. 相似文献
16.
Korpas D Hálek J Dolezal L 《Physiological research / Academia Scientiarum Bohemoslovaca》2009,58(4):473-479
Pulse wave analysis permits non-invasive assessment of arterial elasticity indices. The contour varies in different parts of the circulation. It depends on physiological or pathophysiological conditions of the organism. The pathological events like arteriosclerosis or diabetes have a primary effect to the artery elasticity. Hypertension or some heart diseases also influence the pulse wave velocity and resulted in earlier wave reflections. There are several methods of pulse wave measurements based on different principles and depending on the type of measured pulse wave. The evaluation parameters can be assessed from the time domain, derivations, velocity or frequency domain. The main aim of this review article is to offer a recent overview of pulse wave measurement parameters and main results obtained. The principles of pulse wave measurement and current experience in clinical practice are shortly discussed too. 相似文献
17.
一个新的脑电信号分析系统:小波分析理论的运用 总被引:2,自引:2,他引:0
小波变换是一种把时间、频率(或尺度)两域结合起来的分析方法。它被誉为“分析信号的数学显微镜”。本系统将小波变换用于脑电信号分析,是一个在Windows3.1下开发的脑电分析系统。 相似文献
18.
Computer-controlled pulse modulation system for analysis of photoacoustic signals in the time domain
A newly developed photoacoustic system for measurement of photosynthetic reactions in intact leaves is described. The system is based on pulsed light-emitting diodes, the pulse program and pulse response analysis being computer controlled. Separation of various components in the overall photoacoustic signal is achieved by curve fitting analysis of the responses following individual measuring light pulses in the millisecond time domain. This procedure is in distinction to the conventionally used analysis in the frequency domain, with the advantage that various signal components are obtained by on-line deconvolution, yielding simultaneous recordings of photothermal (complement of energy storage) and photobaric (evolution and uptake) signals. The basic components of the new system are described by block diagrams and the principal steps for deconvolution of the overall photoacoustic response are outlined. An example of application with simultaneous recording of chlorophyll fluorescence is given. It is apparent that the photobaric uptake component represents a significant part of the overall signal, particularly during induction of photosynthesis after dark-adaptation. This component probably contains not only O2-uptake but uptake of CO2 as well.Abbreviations PA
photoacoustic
- LED
light-emitting-diode
- RAM
random access memory 相似文献
19.
E. D. Young 《Bulletin of mathematical biology》1968,30(3):359-385
The arterial system is characterized geometrically as a system of branched elastic fluid lines whose frequency response is
then known in the sense of the Fourier transform. For convenience of visualization the transient response of the individual
tube to an input pressure-flow pair is represented in the time domain by kernel functions indicating the hybrid effect of
viscosity and momentum on the line impedance and damping characteristics. The system as a whole is then divided into a zone
of smaller tubes (below 3 mm) and a zone of larger tubes extending up to the aorta. It is shown that as a system each labyrinth
of tubes below the 3 mm size may be replaced by a single impedance transformation which is dominantly resistive-capacitive.
In the larger tubes, the transformation of the pulse wave at different stations is considered a point of interest. Therefore
hand calculated examples are worked to derive the response of a system involving some of the larger vessels to a pressure
or flow pulse of the typical shape seen near the heart. The result suggests that the dicrotic wave seen in the pressure pulse
of mammals is due to the hybrid viscosity-momentum nature of the longer fluid lines in relation to the gradation of unmatched
terminal impedances with which they are terminated. Damping of the higher frequency components is also accounted for. 相似文献
20.
Tibial forces are important because they determine polyethylene wear, stress distribution in the implant, and stress transfer to underlying bone. Theoretic estimates of tibiofemoral forces have varied between three and six times the body weight depending on the mathematical models used and the type of activity analyzed. An implantable telemetry system was therefore developed to directly measure tibiofemoral compressive forces. This system was tested in a cadaver knee in a dynamic knee rig. A total knee tibial arthroplasty prosthesis was instrumented with four force transducers located at the four corners of the tibial tray. These transducers measured the total compressive forces on the tibial tray and the location of the center of pressure. A microprocessor performed analog-to-digital signal conversion and performed pulse code modulation of a surface acoustic wave radio frequency oscillator. This signal was then transmitted through a single pin hermetic feed-through tantalum wire antenna located at the tip of the stem. The radio frequency signal was received by an external antenna connected to a receiver and to a computer for data acquisition. The prosthesis was powered by external coil induction. The tibial transducer accurately measured both the magnitude and the location of precisely applied external loads. Successful transmission of the radio frequency signal up to a range of 3m was achieved through cadaveric bone, bone cement, and soft tissue. Reasonable accuracy was obtained in measuring loads applied through a polyethylene insert. The implant was also able to detect unicondylar loading with liftoff. 相似文献