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排序方式: 共有878条查询结果,搜索用时 46 毫秒
11.
Pablo Amster Pablo De Npoli Juan Pablo Pinasco 《Computers & Mathematics with Applications》2008,55(12):2762-2766
12.
In this paper an experimental and theoretical investigation of the forced vibration of a partially immersed fiber has been carried out. An optical method utilizing a forward light scattering pattern has been used to detect a small (<1.0 μm) vibration amplitude of the fiber. The physical and mathematical model of the partially immersed fiber vibration has been put forward. Based on an analytical solution of the model, natural frequencies of the partially immersed fiber vibration have been found; they are consecutive positive roots of the transcendental equation. An “effective” speed of the wave propagation over the fiber has been introduced, which allows one to find the physical meaning of normal modes of the partially immersed fiber vibration. Theoretical predictions agree well with experimental data. The sensor exhibits an excellent sensitivity and could be used for measuring physical properties of fluids and liquid level. 相似文献
13.
我们用石英振子频移法成功地对STM探针与被测表面间的作用力进行了测量,进一步证实了在STM测量时探针与被测表面之间存在着一种作用力的预言,为最终解明该现象的本质提供了一种新的方法。 相似文献
14.
Zhaoxia CaiAuthor VitaeGuoxiang ChenAuthor Vitae Xi HuangAuthor VitaeMeihu MaAuthor Vitae 《Sensors and actuators. B, Chemical》2011,157(2):368-373
A new method for the determination of lysozyme with high sensitivity based on Resonance Rayleigh scattering (RRS) by using Cd doped ZnSe quantum dots (QDs) as a probe was proposed in this experiment. Cd doped ZnSe QDs capped with glutathione were prepared in the water phase. Further, the RRS spectrum, transmission electron microscope, and absorption spectrum of the QDs-lysozyme system have been characterized. In addition, the effects of several factors on scattering intensities were investigated, including pH value of solution, amount of QDs, mixing sequence of each reagent and the coexisting substances. Moreover, the possible mechanism for the RRS enhancement of Cd doped ZnSe QDs-lysozyme system was preliminary discussed. The RRS method for the determination of lysozyme has good sensitivity with the detection limits 6.5 × 10−10 g mL−1. The contents of lysozyme were determined with recoveries of 97.1-101.6% and relativity standard deviation of 2.5-3.1%, respectively. It proved that the method established in our study is very sensitive, rapid, convenient and tolerant for the determination of lysozyme in synthetically and chicken egg white. 相似文献
15.
To achieve strong power coupling, a resonance-type magnetoelectric (ME) transducer with high quality factor is developed to achieve strong ME coupling. The ME transducer employs a type of iron–nickel-based ferromagnetic alloy with constant elasticity and piezoelectric Pb(Zr,Ti)O3 (PZT8) material. The dynamic magnetomechanical behavior of the ferromagnetic alloy is investigated. The result indicates that the strain coefficient of the ferromagnetic alloy at resonance achieves 557.07 nm/A due to the high effective mechanical quality factor of the alloy. The transducer is designed to operate as a half-wavelength, longitudinal resonator. The dynamic performance of the transducer is evaluated by measuring its electrical and vibrational characteristics. The results reveal that (1) the resonance of the transducer occurs at the frequency of 26.9336 kHz with a strain coefficient of 314.74 nm/A, an effective mechanical quality factor of 1600; (2) the ME voltage coefficient achieves 30.07 V/Oe (i.e., 375.875 V/cm Oe) at resonance; (3) the ME output power density at optimal load resistance of 25 kΩ achieves 0.956 mW/cm3 under 0.3 Oe root-mean-square AC magnetic field. The performances indicate that the transducer is promising for ME energy conversion application. 相似文献
16.
核磁共振弥散张量成像(Diffusion Tensor Magnetic Resonance Imaging,DT-MRI)是近年来提出的一项新的医学影像技术。通过利用核磁共振技术测量细胞内多个方向上水分子弥散运动的特征,可以全面充分研究活体组织微细结构。基于犬心室的DT-MRI数据集开展了三维心肌纤维结构的可视化方法及其可视化系统设计与实现的研究。首先利用阈值滤波、中值滤波和邻域平均法对原始DT-MRI数据进行去噪预处理,然后利用体绘制技术、图元显示法和纤维跟踪法对犬心室的DT-MRI数据进行可视化。最后对基于DT-MRI数据的心肌纤维可视化应用进行了详细的需求分析和系统设计,基于VTK(Visualization Toolkit)实现一个DT-MRI数据的心肌纤维可视化和分析系统。实验结果表明该系统具有良好的交互性,为研究心脏结构提供了一个有力可视化工具。 相似文献
17.
L.E. HelsethAuthor Vitae 《Sensors and actuators. A, Physical》2012,173(1):17-23
We demonstrate a contactless hybrid sensor for the simultaneous detection of light reflectance and eddy currents. The sensor is based on combining an optical system with an RLC self-resonator, wherein the reflected light intensity and resonance frequency are measured. We demonstrate that the hybrid sensor can be used for monitoring metals coated with non-metallic films. Whereas the self-resonator can efficiently distinguish between metals and non-metals, the optical subsystem is sensitive to changes in the reflectance of light. A systematic investigation of the detector response as a function of distance to the material under test is undertaken to characterize its behavior. 相似文献
18.
Carlos Arizmendi Alfredo VellidoEnrique Romero 《Expert systems with applications》2012,39(5):5223-5232
The diagnosis of brain tumours is an extremely sensitive and complex clinical task that must rely upon information gathered through non-invasive techniques. One such technique is Magnetic Resonance Spectroscopy. In this task, radiology experts are likely to benefit from the support of computer-based systems built around robust classification processes. In this paper, a Discrete Wavelet Transform procedure was applied to the pre-processing of spectra corresponding to several brain tumour pathologies. This procedure does not alleviate the high dimensionality of the data by itself. For this reason, dimensionality reduction was subsequently implemented using Moving Window with Variance Analysis for feature selection or Principal Component Analysis for feature extraction. The combined method yielded very encouraging results in terms of diagnostic discriminatory binary classification using Bayesian Neural Networks. In most cases, the classification accuracy improved on previously reported results. 相似文献
19.
Jae Hong Park Tae Yun Kwon Hyung Joon Kim Seung Rae Kim Dae Sung Yoon Chae-Il Cheon Hwan Kim Tae Song Kim 《Journal of Electroceramics》2006,17(2-4):565-572
The PZT thick film cantilever devices fabricated via MEMS process have much attraction because they are appropriate for biological
transducer or sensor, resulting from their large actuating force and relatively high sensitivity especially in liquid. By
means of resonance behavior, theoretical calculation and experimental verification of the PZT thick film cantilever devices
have not been studied before. Accordingly, we focused on the sensitivity analysis and interpretation of the PZT thick film
cantilevers in this study. Especially, the investigation for mass sensitivity of the PZT thick film cantilever is of importance
for physical, chemical and biological sensing application. The PZT thick film cantilever devices were constructed on Pt/TiO2/SiN
X
/Si substrates using screen printing method and MEMS process. The harmonic oscillation response (resonance frequency) was
measured using an optical laser interferometric vibrometer. The effect of cantilever geometry on the resonance frequency change
was investigated. Compared with the theoretical resonant frequency change by mass loading, the experimental resonant frequency
change of the PZT micromechanical thick film cantilever shows a variation of less than 2%. Mass sensitivities are estimated
to be 30.7, 57.1 and 152.0 pg/Hz for the 400 × 380 μm, 400 × 480 μm and 400 × 580 μm cantilever, respectively. 相似文献
20.