Evolutionary Computing Based Area Integration PWM Technique for Multilevel Inverters

The existing multilevel carrier-based pulse width modulation (PWM) strategies have no special provisions to offer quality output, besides lower order harmonics are introduced in the spectrum, especially at low switching frequencies. This paper proposes a novel multilevel PWM strategy to corner the advantages of low frequency switching and reduced total harmonic distortion (THD). The basic idea of the proposed area integration PWM (AIPWM) method is that the area of the required sinusoidal (fundamental) output and the total area of the output pulses are made equal. An attempt is made to incorporate two soft computing techniques namely evolutionary programming (EP) and genetic algorithm (GA) in the generation and placement of switching pulses. The results of a prototype seven-level cascaded inverter experimented with the novel PWM strategies are presented

Phase Shifter and LNA Design for Satellite Communication

Phased arrays are being used in satellite communication systems in order to provide wireless data to mobile vehicles, ships and even aircrafts. This thesis focuses on the design of phase shifter, which is designed for the transmitter chain and low noise amplifier, which will be used in the receiver chain. The phase shifter is controlled using a digital-to-analog controller. This gives rise to quantization lobes which can fail the spectrum efficiency test. Careful analysis indicates that a minimum phase resolution needed for this application is around 6-bit. This research reviews various integrated circuit phase shifter topologies to come up with one that will meet the specifications for this system. A combination of reflective-type phase shifter and switch-type phase shifter is designed using 65-nm CMOS technology to provide a full 360 degree phase shift range with no power consumption. The measured insertion loss is about 13.05 +/- 2.75 dB at 29.75 GHz with a return loss of about 10 dB or greater. The antenna gain-to-temperature ratio, which is a common figure of merit used in satellite communication, must be met on the receiver side of the phased array system. Through link budget analysis, it was decided that two low noise amplifiers are needed to satisfy the specified gain-to-noise ratio; one off-chip low noise amplifier that is closer to the antenna and another on-chip low noise amplifier. This alleviates the constraints on both low noise amplifiers and allows for a more simple and cost-efficient design. This research focuses on the design of the on-chip low noise amplifier using 130-nm CMOS technology. The receiver chain operates in k-band; thus, the low noise amplifier is designed at 20 GHz. A gain of about 21 dB is achieved, with an output return loss above 10 dB, a 1-dB compression point at -23 dBm and a nominal power consumption of about 6.84 mW. The simulated noise figure for this low noise amplifier design is about 3.7 dB

A Dimmable Resonant Inverter Electronic Ballast with Unity Power Factor

The conventional line-frequency magnetic ballast is heavy and bulky, which is too kept inside the compact fluorescent lamp (CFL). The paper describes about single stage dimmable electronic ballast with very high power factor and its high efficiency. A compact lamp power circuit is designed by using integrating a buck boost power factor corrector with a current-fed resonant inverter. Then the integration process gives a single power-processing unit that minimizes the number of circuit components. In this paper the proposed resonant inverter will reduces the circulating current in the resonant tank. It also allows simple gate drivers to be used so that isolation devices can be eliminated. The design, analysis and simulation were done using MATLAB SIMULINK. DOI: 10.17762/ijritcc2321-8169.150511

Modeling and simulation of a wirelessly-powered thermopneumatic micropump for drug delivery applications

This paper presents modeling and finite element analysis of a thermopneumatic micropump with a novel design that does not affect the temperature of the working fluid. The micropump is operated by activating a passive wireless heater using wireless power transfer when the magnetic field is tuned to match the resonant frequency of the heater. The heater is responsible for heating an air-heating chamber that is connected to a loading reservoir through a microdiffuser element. The solution inside the reservoir is pumped through a microchannel that ends with an outlet hole. The thermal and pumping performances of the micropump are analyzed using finite element method over a low range of Reynold’s number ⩽ 10 that is suitable for various biomedical applications. The results demonstrate promising performance with a maximum flow rate of ∼2.86 μL/min at a chamber temperature of 42.5 ºC, and a maximum pumping pressure of 406.5 Pa. The results show that the developed device can be potentially implemented in various biomedical areas, such as implantable drug delivery applications

Metamodel-based Optimization of a PID Controller Parameters for a Coupled-tank System

Liquid flow and level control are essential requirements in various industries, such as paper manufacturing, petrochemical industries, waste management, and others. Controlling the liquids flow and levels in such industries is challenging due to the existence of nonlinearity and modeling uncertainties of the plants. This paper presents a method to control the liquid level in a second tank of a coupled-tank plant through variable manipulation of a water pump in the first tank. The optimum controller parameters of this plant are calculated using radial basis function neural network metamodel. A time-varying nonlinear dynamic model is developed and the corresponding linearized perturbation models are derived from the nonlinear model. The performance of the developed optimized controller using metamodeling is compared with the original large space design. In addition, linearized perturbation models are derived from the nonlinear dynamic model with time-varying parameters

Analiza dizajna LCLC rezonantnog invertera za dvostupanjsko dvofazno napajanje

This paper deals with the design analysis and synthesis of power resonant inverter with sinusoidal output voltage for sensitive loads. The proposed filter must be capable of removing higher harmonic components from the supplying voltage to reach a harmonic distortion of roughly 5% in the whole range of the load (0 − 100%). The inverter can be supplied from either single-phase voltage inverter in full- or half- bridge connection, or from simple DC/DC buck converter. Non-symmetrical control causes higher harmonic content, both odd and even. Simulation and experimental results based on designed parameters and subsequently obtained from Matlab and OrCad models confirm good quality of output quantities, voltage and current.Tema je ovog članka analiza dizajna i sinteza učinskog rezonantnog invertera sa sinisuidalnim izlaznim naponom za osjetljive terete. Predloženi filtar mora moći filtrirati više harmonike ulaznog napona kako bi distorzija harmonika bila oko 5% u čitavom radnom području (0−100%). Inverter se može napajati ili iz jednofaznog naponskog invertera u mosnom ili uzrokuje pojavu viših harmonika u signalu, kako parnih tako i neparnih. Simulacijski i eksperimentalni rezultati temeljeni na sintetiziranim parametrima dobivenim od modela napravljenih u programskim paketima Matlab i OrCad potvr.uju dobru kvalitetu izlaznih veličina napona i struje

Validation of verbal autopsy: determination of cause of deaths in Malaysia 2013

Background Mortality statistics by age, sex and cause are the foundation of basic health data required for health status assessment, epidemiological research and formation of health policy. Close to half the deaths in Malaysia occur outside a health facility, are not attended by medical personnel, and are given a lay opinion as to the cause of death, leading to poor quality of data from vital registration. Verbal autopsy (VA) is a very useful tool in diagnosing broad causes of deaths for events that occur outside health facilities. This article reports the development of the VA methods and our principal finding from a validation study. Methods A cross sectional study on nationally representative sample deaths that occurred in Malaysia during 2013 was used. A VA questionnaire suitable for local use was developed. Trained field interviewers visited the family members of the deceased at their homes and conducted face to face interviews with the next of kin. Completed questionnaires were reviewed by trained physicians who assigned multiple and underlying causes. Reference diagnoses for validation were obtained from review of medical records (MR) available for a sample of the overall study deaths. Results Corresponding MR diagnosis with matched sample of the VA diagnosis were available in 2172 cases for the validation study. Sensitivity scores were good (>75%) for transport accidents and certain cancers. Moderate sensitivity (50% - 75%) was obtained for ischaemic heart disease (64%) and cerebrovascular disease (72%). The validation sample for deaths due to major causes such as ischaemic heart disease, pneumonia, breast cancer and transport accidents show low cause-specific mortality fraction (CSMF) changes. The scores obtained for the top 10 leading site-specific cancers ranged from average to good. Conclusion We can conclude that VA is suitable for implementation for deaths outside the health facilities in Malaysia. This would reduce ill-defined mortality causes in vital registration data, and yield more accurate national mortality statistics.This study was funded by the Ministry of Health, Malaysia

Silicon central pattern generators for cardiac diseases

Belgium Herbarium image of Meise Botanic Garden

Silicon central pattern generators for cardiac diseases

Cardiac rhythm management devices provide therapies for both arrhythmias and resynchronisation but not heart failure, which affects millions of patients worldwide. This paper reviews recent advances in biophysics and mathematical engineering that provide a novel technological platform for addressing heart disease and enabling beat-to-beat adaptation of cardiac pacing in response to physiological feedback. The technology consists of silicon hardware central pattern generators (hCPGs) that may be trained to emulate accurately the dynamical response of biological central pattern generators (bCPGs). We discuss the limitations of present CPGs and appraise the advantages of analog over digital circuits for application in bioelectronic medicine. To test the system, we have focused on the cardio-respiratory oscillators in the medulla oblongata that modulate heart rate in phase with respiration to induce respiratory sinus arrhythmia (RSA). We describe here a novel, scalable hCPG comprising physiologically realistic (Hodgkin–Huxley type) neurones and synapses. Our hCPG comprises two neurones that antagonise each other to provide rhythmic motor drive to the vagus nerve to slow the heart. We show how recent advances in modelling allow the motor output to adapt to physiological feedback such as respiration. In rats, we report on the restoration of RSA using an hCPG that receives diaphragmatic electromyography input and use it to stimulate the vagus nerve at specific time points of the respiratory cycle to slow the heart rate. We have validated the adaptation of stimulation to alterations in respiratory rate. We demonstrate that the hCPG is tuneable in terms of the depth and timing of the RSA relative to respiratory phase. These pioneering studies will now permit an analysis of the physiological role of RSA as well as its any potential therapeutic use in cardiac disease

Investigation of the apoptotic effects of cycloart-24-ene-36β,26-diol from Aglaia exima on selected breast cancer cell lines / Deepa Jeevananthan

The main purpose of this study is to investigate the cytotoxic potential and anticancer mechanism of cycloart-24-ene-3β,26-diol isolated from the leaves of Aglaia exima of the Meliaceae family through a bioassay-guided fractionation. In vitro assays of this compound were conducted on two cancer cell lines—hormone-dependent breast adenocarcinoma cells (MCF-7) and hormone-independent breast adenocarcinoma cells (MDA-MB-231) in comparison with the normal human mammary epithelial cell line (hTERT-HME1). Cell viability was assessed using the MTS (3-[4,5-dimethylthiazol-2- yl]-5-[3-carboxymethoxyphenyl]-2-[4-sulphophenyl]-2H-tetrazolium, inner salt) assay. Flow cytometry analysis was used to determine the mode of cell death and cell cycle arrest caused by the compound. Caspase 3/7 assay was performed to investigate caspase activation, while aromatase inhibitory activity was examined using the CYP19-MFC assay. The results showed that cycloart-24-ene-3β,26-diol is cytotoxic to MCF-7 and MDA-MB-231 in a dose- and time-dependent manner. Conversely, cycloart-24-ene3β,26-diol did not significantly affect the viability of normal mammary cells within a similar concentration range. Flow cytometric analysis of annexin V/propidium iodide (PI) dual staining showed that cell death was through apoptosis. The apoptotic effects was further confirmed by caspase 3/7 activation. Cell cycle analysis showed that cycloart-24-ene-3β,26-diol caused G1-S phase arrest in MCF-7. Besides, we found that cycloart-24-ene-3β,26-diol inhibited CYP19 (aromatase), suggesting a potential aromatase inhibitor. In conclusion, cycloart-24-ene-3β,26-diol, a natural compound from the leaves of Aglaia exima may have the potential to be further developed into a chemopreventive agent for breast cancer