Advanced Engineering Forum Vol. 38

Abstract: This paper presents a novel circuit design technique for an inductor type step-down buck converter in a blue-tooth receiver. Based on the superposition principle, a model of this system is proposed and verified by simulation. The overshoot phenomena is well controlled when R, L and C components are chosen by a relation |Z_L|=|Z_C|=2R based on a balanced charge and discharge time condition T=2π√LC=4πRC. Furthermore, a fundamental harmonic notch filter is recommended to keep small ripple which is designed at the fundamental harmonic frequency of PWM signal. A battery supply voltage of 3.6V was applied to the converter and the output voltage was set to 1.8V. The design of this methodology is given through the CMOS technology. As a result, a 1.8V stable step-down buck converter is designed for a blue-tooth low-IF receiver which the ripple is smaller than 0.2mVpp.

Abstract: This paper proposes a method to design a flat pass-band gain with two RC band-stop filters for a 4-stage passive RC polyphase filter in a Bluetooth receiver. Based on the superposition principle, the transfer function of the poplyphase filter is derived. However, the pass-band gain of this filter is not flat on the positive frequency domain. There are two local maximum values when the input signals are the wanted signals. Therefore, two RC band-stop filters are used to improve the pass-band gain of these local maximum values. As a result, a flat pass-band gain passive RC poly-phase filter is designed for a Bluetooth low-IF receiver which image rejection ratio is-36dB, and ripple gain is 0.47dB.

Abstract: Patients with Parkinson’s disease or stroke show symptoms of motor disorders that disturb gait and mobility. Although the objective and/or quantitative assessment of the rehabilitation to evaluate the degree of improvement is significantly important, three-dimensional (3D) motion capture systems to evaluate body movement are very expensive and require many markers attached to patients. The purpose of this study was to investigate the feasibility of medical and healthcare ICT-supported rehabilitation assistance systems for 3D gait analysis using low-cost markerless motion capture devices in response to practical clinical needs. The clinical data obtained by our system showed that there were significant differences between the patient group and the healthy subject group.

Abstract: There are many types of wind turbine. Large propeller-type wind turbines are used mainly for large wind farms and offshore wind power generation. Small vertical-axis wind turbines (VAWTs) are often used in distributed energy systems. In previous studies on wind turbines, the basic characteristics such as torque coefficient have often been obtained during rotation, with the turbine rotating at a constant speed. Such studies are necessary for the proper design of wind turbines. However, it is also necessary to conduct research under conditions in which the wind direction and wind speed change over time. Numerical simulation of the starting characteristics is carried out in this study. Based on the flow field around the wind turbine, the force required to rotate the turbine is calculated. The force used to stop the turbine is modeled based on friction in relation to the bearing. Equations for the motion of the turbine are solved by their use as external force. Wind turbine operation from the stationary state to the start of rotation is simulated. Five parameters, namely, blade length, wind turbine radius, overlap, gap, and blade thickness, are changed and the optimum shape is obtained. The simulation results tend to qualitatively agree with the experimental results for steadily rotating wind turbines in terms of two aspects: (1) the optimal shape has an 20% overlap of the turbine radius, and (2) the larger the gap, the lower the efficiency.

Abstract: A "whitelist network switch (WLS)", which can monitor and filter packets based on a whitelist, is particularly effective for stronger information security in closed network environments, such as in factories. This paper focuses on the base network environment for a nurse call system within a large hospital. This network environment is of particular importance to security, and the types of network protocols used are limited. We note important points regarding the practical operation and effectiveness of WLS through two approaches: (i) test introduction into an existing, actual hospital network system; (ii) test introduction in an experimental nurse call system environment.