Papers by Author: Zhong Hai He

Abstract: External micro vibration is an important obstacle factor for the measuring result of scanning tunneling microscopy. In order to achieve better result, the influence of vibration must be eliminated. In this study, a large range new sensor with two nano stages is built up to detect the micro vibration for the compensation of the results. Finnaly, the vibration detection experiments are made to illustrate the rationality of the sensor.

Abstract: Scanning tunneling microscopy is one of the surface measurement instruments in micro and nano field, and the Z-direction resolution is 0.01nm. So it is easily affected by the external factor in the course of measurement. The influence of vibration has already become one of main obstacles for improving the nano measuring accuracy. In this article, micro vibration measurement based on the tunneling effect is referred. A new sensor design of double displacement stages is brought to study the micro vibration, and both stages have the nano level displacement and resolution. Using this sensor, the tunneling effect is realized and the micro vibration is measured. The experiment results show this design has stable performance, and the results can be used to be a reference for the compensation of scanning tunneling microscopy.

Abstract: There are many parameters that be used to represent typical breath flow, mainly divided into three types: one is temporal, the second is frequency, and the last is pressure driven model. The temporal parameters include breath period, tidal volume, inspiration expiration ratio, and functional residual volume, to name a few. The frequency parameters mainly include every harmonic content variation. The pressure driven model use mechanical parameters to calculate flow. All the methods above have one common disadvantage: they do not take variation into account. We proposed here that the fourth type parameter should be also used to describe flow pattern, namely fractal parameter, fractal dimension of breath flow signal. The necessity and advantage of the fractal parameter is elucidated. The fractal dimension parameter is optional because of its stability compared with other parameters.

Abstract: Fractal signal feature in breath flow is verified by many articles. So the generate fractal feature have two meanings, one to decrease damage to lung in mechanical ventilation because of natural similar, two to increase similarity in breath simulation used in medical patient simulator. The main feature of fractal signal is self-similar. Some algorithms have been proposed using fractional Brownian motion simulation. In this paper we use Weierstrass function combination to generate fractal signal. The method includes all fractal features and easy to realize in algorithm compared with fractional Brownian motion.

Abstract: In this paper how to generate respiratory flow that has fractal signal feature is introduced. Physiological signal have fractal feature have been verified by many researchers, such as heart beat rate, interbreath interval. Mechanical ventilators are used to provide life support for patients with respiratory failure. But these machines can damage the lung, causing them to collapse. On the other hand, fractal feature can be used as an indication of health situation; as a result in patient simulation the physiological signal should also have fractal features. The fractal feature is generated by fractional Brownian motion simulation. The fractal dimension is decided by Hurst exponent in routine. The algorithm is realized by R language and result is input into LabVIEW which have friendly interface and easy for simulation control usage. The method can be used in design of mechanical ventilator and medical patient simulator.

Abstract: A high speed spectral optical coherence tomography (SOCT) system was demonstrated. An achievable scanning speed of 92k line/sec has been reached and it can acquire 3-dimensional data sets in ~3 second. The axial resolution of ~13μm and lateral resolution of ~16μm have been realized. The system is capable of a theoretical depth measurement 3.2mm in air. We also measured the sensitivity performance corresponding to difference depth and it demonstrated that our system can differentiate signal form noise at 3mm pathlength difference. Using the system, human palm skin was measured in vivo.

Abstract: Adding glucose in water will cause two influences on the aqueous solution: one is absorption coefficient addition of glucose; the other is absorption coefficient decrease of water because of water displacement. So the total absorption effect is the result of the absorption coefficient increase of glucose and absorption coefficient decrease of water. In this paper the absorption coefficient of glucose water is analyzed in consideration of water displacement. By data of handbook, we deduce a relationship between the glucose absorption coefficient addition and water absorption coefficient decrease. When one molar glucose is added into water, 6.15 molars water molecular is displaced. The wavelength selection in glucose detection should be at the place where the combined absorption is maximum. The wavelength of widely used in blood glucose concentration detection, e.g. 1.6μm, is selected as an example for analysis. When glucose is added into water, the linear relationship between glucose concentration and absorption coefficient is hold on. On the other hand, when the water molecular is decreased, the water absorption coefficient will decreased, too, which will decrease the total absorption coefficient compared to the situation without water displacement. In general, water displacement will decrease the sensitivity of absorption coefficient to glucose concentration.

Abstract: A lung simulator utilizing flow track to simulate spontaneous breathing is presented as an alternative to the existed lung system in the medical patient simulator. The hardware of simulator is similar and updated from Meka’s paper. The existing lung system can be divided into two main types. One is traditional bellows driven mechanical lung system, the other is bellow-less lung simulator driven by carinal pressure that to be controlled. Our lung simulator is upgraded from bellow-less simulator. The research focus on the flow pattern the lung simulator generated which can image the lung mechanical factors directly. The flow pattern of the lung simulator is modeled by transfer function combined with respiratory muscle pressure, which is the target that the bellow-less lung simulator to track. The target flow pattern is tracked by PID algorithm widely used in automation filed and realized by Control Design and Simulation module in LabVIEW. We simulate the normal respiratory motion by flow track in this study. The pathology breath flow can be simulated by change of resistance, compliance or muscle pressure, which is easy to adjust in the LabVIEW program.