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11.
基于离散小波变换提取脑机接口中脑电特征 总被引:13,自引:0,他引:13
在脑机接口中,针对脑电特征提取利用单一种类信息、使用数据量大、分类性能较差等缺点,提出一种新颖的基于离散小波变换的方法。分析了小波变换特征提取的特点和特征表示方式,用Daubechies类db4小波函数对脑电信号进行6层分解,抽取小波变换各子带关键的部分逼近系数、小波系数、小波子带系数均值组成特征向量。以分类正确率为指标检验了提取特征的性能。实验结果表明,这种方法能够利用少量数据提取脑电信号本质特征,具有较高的分类性能,为利用脑电识别人的不同意图提供了快速而有效的手段。 相似文献
12.
A computer-interfaced photometer and systematic spacing of duplicates to control within-plate enzyme-immunoassay variation 总被引:9,自引:0,他引:9
B W Stemshorn D J Buckley G St Amour C S Lin J R Duncan 《Journal of immunological methods》1983,61(3):367-375
A Multiskan photometer for reading microtiter plate enzyme immunoassays was linked with a time sharing computer to facilitate control of assay variation and analysis of results. The interface that converted photometer output to RS-232-C format required changes to divide the output into segments short enough for input to the computer. To measure within-plate variation and investigate how the method of allocating sample duplicates to plate wells may affect the estimation of sample variance, uniformity tests were conducted with 47 plates. Coefficients of variation (CV) among wells within-plates ranged from 4.6 to 20.7% and in two-thirds of the plates exceeded 10%. Duplicates allocated to adjacent wells (method 1) gave consistently higher CV for sample means than duplicates allocated to opposite plate quadrants (method 2). In general, the CV by method 2 was about 30% smaller than that by method 1. Analysis of variance confirmed the effectiveness of the quadrant pattern of duplicate allocation as a method of controlling variation that arises from well position effects. 相似文献
13.
We have previously demonstrated that there was no significant difference between the affinity of bone to bio-inert ceramics and stainless steel in a histological study. In this study, the bone-implant interface shear strength of alumina ceramics (AI2O3), zirconia ceramics (ZrO2), stainless steel (SUS316L) and sintered hydroxyapatite (HA) were compared in 19 dogs using a transcortical push-out model of the femur 4 and 12 wk after implantation. The interface shear strength of HA was significantly greater than that of alumina ceramics, zirconia ceramics and stainless steel (P < 0.001). There was no significant difference between bio-inert ceramics and stainless steel. 相似文献
14.
The paper presents an adaptive noise canceller (ANC) filter using an artificial neural network for real-time removal of electro-oculogram
(EOG) interference from electro-encephalogram (EEG) signals. Conventional ANC filters are based on linear models of interference.
Such linear models provide poorer prediction for biomedical signals. In this work, a recurrent neural network was employed
for modelling the interference signals. The eye movement and eye blink artifacts were recorded by the placing of an electrode
on the forehead above the left eye and an electrode on the left temple. The reference signal was then generated by the data
collected from the forehead electrode being added to data recorded from the temple electrode. The reference signal was also
contaminated by the EEG. To reduce the EEG interference, the reference signal was first low-pass filtered by a moving averaged
filter and then applied to the ANC. Matlab Simulink was used for real-time data acquisition, filtering and ocular artifact
suppression. Simulation results show the validity and effectiveness of the technique with different signal-to-noise ratios
(SNRs) of the primary signal. On average, a significant improvement in SNR up to 27 dB was achieved with the recurrent neural
network. The results from real data demonstrate that the proposed scheme removes ocular artifacts from contaminated EEG signals
and is suitable for real-time and short-time EEG recordings. 相似文献
15.
The series equivalent resistance R and capacitance C of metal/saline electrode/electrolyte interfaces were measured as a function
of frequency (100 Hz–20k Hz) and current density (0·25 to 1000 A m−2) for eight typical electrode metals. For each of the metals tested, R decreased and C increased as the current density was
increased above a critical value (with the exception of silver and MP35N at frequencies above 1 kHz for which R increased
and C decreased slightly). With the exception of copper, the current density linearity limit (for 10 per cent decrease in
R or 10 per cent increase in C) increased with increasing frequency and, in most cases, the current density linearity limit
for 10 per cent increase in C was slightly less than that for 10 per cent decrease in R. Among the metals tested, copper and
aluminium had the lowest current carrying capability and rhodium had the highest current-carrying capability. The current
carrying capabilities of 316 SS, platinum, silver and MP35N, were intermediate and similar. With increasing current density,
an increase in the electrode/electrolyte capacitance was the most sensitive indicator of the current-carrying linearity limit. 相似文献
16.
In order to study the interface of calcium phosphate bioglass ceramics, cylinders of standard size were implanted in the tibiae of rabbits. The materials were evaluated by radiography, light microscopy and microradiography. Bioceramics with hydroxyapatite surface give rise to a closer contact with new bone than calcium phosphate glass ceramics. 相似文献
17.
介绍基于USB2.0接口的医用超声内窥镜旋转扫描成像的设计与实现。根据超声成像的特点,本系统采取脉冲回波成像方式,文中介绍了超声波激发、接收电路以及收发隔离电路。针对旋转扫描的特点,设计了基于FPGA的同步控制电路和基于USB2.0接口的数据传输电路。对采集到的原始图像,进行坐标变换,获得了按直角坐标显示的灰度图像。利用连续旋转马达对实际物体扫描成像的实验结果,验证了系统的正确性。 相似文献
18.
如何从脑电信号中快速准确地识别出P300成分是脑-机接口研究中的一个热点问题.针对P300的识别问题,我们提出了一种将F-score特征选择与支持向量机相结合的判别方法,该方法采用F-score特征选择减少输入特征的维数,以克服支持向量机算法判别速度慢的缺点;然后借助支持向量机算法良好的分类性能实现P300的识别.本文在BCI Competition 2003的P300实验数据集上对该方法进行了验证,结果表明,在5次重复实验中该方法的识别准确率达到了100%,且判别速度与未经特征选择的传统支持向量机算法相比提高了近2倍. 相似文献
19.
Bioreactions at the tissue/hydroxyapatite interface 总被引:2,自引:0,他引:2
C.A van Blitterswijk J.J. Grote W. Kuÿpers C.J.G. Blok-van Hoek W.Th. Daems 《Biomaterials》1985,6(4):243-251
The events at the hydroxyapatite implant material/tissue interface in the rat middle ear were studied by light microscopy, autoradiography, morphometry, transmission electron microscopy (TEM), scanning electron microscopy (SEM), and X-ray microanalysis. Deposition of calcium, partially in the form of calcium phosphate, was found at the interface. Resorption of the implant material occurred as the result of mono- and multinuclear phagocyte activity. Resorption decreased 6 mnth after the operation, possibly due to the decreasing number of phagocytes at the interface and the increasing amount of bone in the macropores. 相似文献
20.
By use of scanning electron microscopy (SEM), together with energy dispersive chemical analysis, a study has been made of the comparison of an in vitro method of assessing interface reactions between bone and ceramic implants with the naturally occurring changes seen in the rat ear model. Interface reactions between bone and two ceramic materials were examined following 4 wk in culture and 4 wk implantation. In both cases a gradual chemical change occurred at the calcium silicate surface during the fibrous growth onto the ceramic material. Gradual mineralization of the connective fibres was found at the interface of the calcium silicate material, whereas, in the case of alumina ceramic a connective fibrous bond had formed with no associated chemical change at the ceramic surface. 相似文献