Applied Mechanics and Materials Vols. 475-476

Abstract: In the paper, based on the electrophysiological experimental dada, the neuron model under the pathology condition of Alzheimer Disease (AD) is built. The neuron models dynamic variation characteristics before and after the effect of AD are comparatively studied. Under the currents stimulation, compared with the normal neuron model, the AD neuron models dynamic characteristics have been obviously changed. Its changing range of the membranes interspike intervals (ISIs) obviously narrows, and the discharge patterns change rather single. In addition, its discharge threshold is much higher than the normal neuron models. So AD causes the neuron models excitability to depress markedly. The research reveals the neuron models dynamic characteristics changing under the effect of AD, which shows bioinformatics change of the neuron caused by AD. The research provides some theoretic basis for AD research by the neurodynamics theory.

Abstract: A finite element model was developed to simulate the 3-D velocity and temperature distributions in a vessel system including a bifurcated blood vessel and two branches. The effect of the angel between vessels and bifurcation ratio were taken into account, and the local Nusselt number at three typical radial angels and the mean Nusselt number on a section in the branching vessel were obtained. Results show that: the flow and temperature fields were highly unlike the distributions of a single vessel; the local Nusselt number were different at different radial angels; In the entrance region of the branching vessel the mean Nusselt number on a section was larger than that in a single vessel, and there was a maximum of mean Nusselt number whose value and location varied as the different furcating angel or bifurcation ratio; the mean Nusselt number decays rapidly at a small bifurcation ratio.

Abstract: For hemodynamic simulation and heat transfer analysis of blood, it is necessary to generate a three-dimensional model of arterial tree. Referring to the approach of Constrained Constructive Optimization (CCO), a new method based on bifurcation law, Poiseuilles law and mass conservation was proposed to model arterial trees directly in simulation objects. The formulas for calculating the bifurcation ratios and the way to determine the location of bifurcation point were presented in the paper. In this model, the radius of the root segment was constant, the terminal pressure was unknown and the bifurcation exponent was variable. In order to demonstrate the feasibility of this method, an arterial tree was constructed in a spherical tissue.

Abstract: In the passive dynamic harmonic filter, the variation of the capacitor value has an influence on the filtering performance. To analyze the relationship between the capacitor capacity (C) and the filtering performance, the experimental investigations are finished in this paper. The test results show that the variation of capacitor value can result in the resonance point drifting and the proper increase of capacitor capacity can increase the maximum of the absorbed harmonic current.

Abstract: The started motors with the discrete frequency converter are characterized by high starting torque and a large number of harmonics when the motors draw heavy-loads. It may pull down the voltage of the power supply net work and influence the other electrical devices. Furthermore, it increases the motor temperature, which may lead to motor damage. Therefore, an integrated device of motor discrete variable frequency starting and harmonic filtering was developed. In this paper, a controller is designed to control the motor during the soft starting/stopping and keep the harmonics in permitted ranges by harmonic filtering. The following works have been done in the study: the needs analysis of the controller, design the hardware based on the PLC and the software design of the controller. The motor starter developed with this controller has been successfully applied to the loads of the drive equipments. It can improve the starting performance when the motors draw the heavy-loads, save energy, stabilize the voltage of the power supply network.

Abstract: The objective of this work is to simulate a kind of passive harmonic filter based on IGBT to improve the power factor of the power supply system, then to verify the feasibility of reactive power compensation and harmonic suppression. According to the topological structure and working principle of passive dynamic harmonic filter based on IGBT, the simulation model of the system has been set by the Simulink tool. Simulation results show that the passive dynamic harmonic filter based on IGBT can compensate the corresponding reactive power and suppress harmonic in the power grid. The research of this paper has laid a theoretical foundation for this filter in industrial applications.

Abstract: Panoramic parking assistant system demands for the high performance of hardware when capturing, storing, processing image and demands for capturing from four video sources. This paper analyzes the microprocessor TM320DM642 and TM320DM6467(DM642 and DM6467 for short), both of which are based on the DaVinci technology, and presents two solutions for four video capturing and processing, as DM642+TVP5150 and DM6467+TVP5158. Hardware platform based on DM642 has been established and tested. High resolution panoramic video of bird's-eye view is rendered smoothly on the platform. The result shows that microprocessor of DaVinci technology has excellent performance for the panoramic parking assistant system, and DM642 microprocessor meets the hardware demands of the panoramic parking assistant system.

Abstract: The development and utilization of different structural materials, optimization of the cantilever geometry and power harvesting circuit are the most commonly methods used to increase the power density of MEMS energy harvester. This paper discusses the cantilever geometry optimization process of low power and low frequency of bimorph MEMS energy harvester. Three piezoelectric materials, ZnO, AlN and PZT are deposited on top and bottom of the cantilever Si substrate. This study focuses on the optimization of the cantilevers length, width, substrate thickness and PZe thickness in order to achieve lower than 600 Hz of resonant frequency. The harvested power for this work is in the range of 0.02 ~ 194.49 nW.

Abstract: This paper presents a digital compensation device based on two multiplying digital-to-analog converters (M-DAC) whose reference voltages are the same standard AC signals. The output of two M-DACs, which is controlled by software coding, are used as the in-phase and the quadrature component through a reverse proportional amplifier and a derivation circuit respectively. Then the four-quadrant compensative signal can be got after the in-phase and quadrature components have been synthesized. The resolution of digital compensation device is determined by the M-DAC, and usually can be reached to 10ppm of the reference voltage. Measurement results show that the linearity of the presented digital compensation device is about 3.7×10^-5.

Abstract: This paper presents a low distortion analog front-end (AFE) circuit to process electret microphone output signal. A source follower is employed for the input buffer to interface electret microphone directly to the IC with level shifting. A single-ended to differential converter with output common-mode control is presented to compensate the common-mode variation resulted from gate to source voltage variation in the source follower. A replica stage is adopted to control the output bias voltage of the single-ended to differential converter. The prototype AFE circuit fabricated in a 0.35μm CMOS technology achieves 68.2dB peak SNDR and 79.9dB SFDR over an audio signal bandwidth of 20kHz with 2.5V supply while consuming 1.05mW.