A novel multilevel DC - AC converter from green energy power generators using step-square waving and PWM technique

Green energy sources or renewable energy system generally utilize modular approach in their design. This sort of power sources are generally in DC form or in single cases AC. Due to high fluctuation in the natural origin of this energy (wind & solar) source they are stored as DC. DC power however are difficult to transfer over long distances hence DC to AC converters and storage system are very important in green energy system design. In this work we have designed a novel multilevel DC to AC converter that takes into account the modular design of green energy systems. A power conversion efficiency of 99% with reduced total harmonic distortion (THD) was recorded from our simulated system design

Real time telemedical health care systems with wearable sensors

The time between detection and response to chronic diseases could go a long way in saving lives. The current trend in health monitoring systems is to move from the hospital centered device to eventually portable personal devices. Hence,Telemedical health care involves the remote delivery of medical care service to either out-of-hospital or admitted patients through wireless network and computer information technology. This paper systematically reviews the most recent works in telemedical health care system to propose a more efficient model. The focus is more on wearable sensors and devices with most attention given to cardiovascular patients in recent times. The huge literature available reflects the size of activity and attention given to telemedicine. The reviewed works are published within the last five years. Furthermore, the proposed systems are compared in terms of their connectivity, targeted application, type of sensor used, etc. Our study reveals Telemedicine to be a profound field with researchers from multidisciplinary sectors. However, there are still many gaps that need to be filled before maturity. Factors such as efficient wireless transmission, cyber data security, sensor design and integration, device miniaturization and intelligent algorithm for multi parameter data fusion require further considerations

Induced current distribution in 3D soil model as lightning impulse discharge strike earth surface

Discharge current distribution generated as a lightning strike traverse from the atmosphere into a soil surface and below with varying conductivity were investigated using a laboratory-size electrode configuration system consisting of a point discharge electrode and nine under-soil grounding electrodes. Discharge emission and the electric potential of the soil were with significant change upon slight variation in soil conductivity across the surface and along with an increase in depth. Non-linear degradation phenomena in the soil conductivity also occur after a subsequent discharge of lightning strike indicating a breakdown of soil properties. The results of a numerical model in COMSOL Multiphysics AC/DC module further shed a graphical illustration of the current pathway validating the experimental data. © 2019 IEEE

Analytical investigation of step-square wave in time and frequency domain using transform equations

A unit step function can be used for generating a pulse of given width and height. The same pulse can be used for generating a stepped waveform of known levels and a given width in time-domain which when translated to frequency or complex S-domain provides the fundamental constituent frequencies. This paper is about studying the frequency of the above-generated functions in time as well in the frequency domain using transform equations. The result of this simulations are indicative of the correlation between step square waving and reductions in total harmonic distortion (THD) during DC to AC conversion. A decrease in the pulse width difference between each step shows better conversion with reduced harmonics when subjected to simple passive filter of low transfer function

Watermarking in protecting and validating the integrity of digital information: a case study of the holy scripture

This paper presents digital watermarking for validating and protecting the integrity of digital Holy Quran in Portable Document Format (PDF). The need arises as minute alteration to text or content of Holy Scriptures could result in a devastating situation in the belief of the owners. By this research we have designed and evaluated a simple yet fragile and fidel image PDF digital watermarking technique using 2 and 4 level Discrete Wavelet Transform (DWT) in order to protect and detect the authenticity of a digital Holy Quran. A 512×512 PDF Quran was used as cover image and DWT carried out on it following the watermark image embedding process of a 128×128 and 32×32 on different trials. The Inverse DWT then carried out to obtain the watermarked Quran PDF. Imperceptibility test using Peak Signal to Noise Ratio (PSNR) and Structural Similarity Index (SSIM) were used to evaluate the fidelity and fragility of the watermark scheme over four different embedding gain (k) of 0.001, 0.002, 0.003 and 0.004 for a more robust system. The experimental results demonstrated that our system was indeed effective

Design of simple DC-to-DC wireless power transfer via inductive coupling

This research presents a wireless DC-to-DC power transfer over a short distance. Distance of remotely located target from the source coil and received voltage at the load are the major concern in the Wireless Power Transfer (WPT) applications. The inversely proportional behavior of these parameters degrades the system performance. In order to optimize these values and achieving transfer efficiency, microelectronic circuit is developed and simulated using NI Multisim. The transmitter and receiver modules are constructed and their individual blocks are simulated and analyzed for wireless power transfer. Two inductively coupled coils are designed and used in both transmitter and receiver sections. The inverter is designed using H-bridge with five CMOSFET (IRF520NS, IRF5210S) and its gate signal is generated using NE555 timer IC with two output clock signal where one was inverted using an NMOS inverter. Through simulation, it is observed that with such a design, the power transfer has a limited range, and the range will be smaller for smaller receiving coils and improper alignment. A simulated model is proposed and implemented in this paper. The simulation outputs of each unit is plotted and analyzed separately. In addition, transient plot of load resistance versus output voltage are illustrated to analyze the power of dc-dc power transfer circuit. It is observed that the output voltage is increased correspondingly with increasing load resistance and determined good output voltage is harvested with the optimized load resistance is at 1 kΩ and is 4.25 V. Simulated results shows that the proposed system can transfer power with high efficiency. This proposed system could be made commercially viable through further research work

Automated bank note identification system for visually impaired subjects in Malaysia

Visually Impaired Malaysians find great difficulty in recognizing bank notes as there are no commercially available aid for her currency and not much research done in the area. A very low cost, high efficient system has been proposed to help visually impaired Malaysians identify her bank notes. This system is built around the unique color of her bank note. The system features a sound module, color sensor module and a microcontroller module. These three module offer the system a unique ability to identify Malaysian bank currency and produce audible sound of the currencies’ denomination. The efficiency of the proposed solution has been properly tested on a dataset composed of consecutive randomized banknotes including both positive images (Malaysian banknotes) and negative images (Non Malaysian banknotes and plain color notes) collected under a variety of conditions. The proposed algorithm, achieves overall efficiency of 94.17% recognition rate

Data in transit validation for cloud computing using cloud-based algorithm detection of injected objects

The recent paradigm shift in the IT sector leading to cloud computing however innovative had brought along numerous data security concerns. One major such security laps is that referred to as the Man in the Middle (MITM) attack where external data are injected to either hijack a data in transit or to manipulate the files and object by posing as a floating cloud base. Fresh algorithms’ for cloud data protection do exist however, they are still prone to attack especially in real-time data transmissions due to employed mechanism. Hence, a validation protocol algorithm based on hash function labelling provides a one-time security header for transferable files that protects data in transit against any unauthorized injection. The labelling header technique allows for a two-way data binding; DOM based communication between local and cloud computing that triggers automated acknowledgment immediately after file modification. A two layer encryption functions in PHP was designed for detecting injected object; bcrypt methods in Laravel and MD5 that generate 32 random keys. A sum total of 1600 different file types were used during training then evaluation of the proposed algorithm, where 87% of the injected objects were correctly detected

High voltage discharge profile on soil breakdown using impulse discharge

Grounding terminals are mandatory in electrical appliance design as they provide safety route during overvoltage faults. The soil (earth) been the universal ground is assumed to be at zero electric potential. However, due to properties like moisture, pH and available nutrients; the electric potential may fluctuate between positive and negative values that could be harmful for internally connected circuits on the grounding terminal. Fluctuations in soil properties may also lead to current crowding effect similar to those seen at the emitters of semiconductor transistors. In this work, soil samples are subjected to high impulse voltage discharge and the breakdown characteristics was profiled. The results from profiling discharge characteristics of soil in this work will contribute to the optimization of grounding protection system design in terms of electrode placement. This would also contribute to avoiding grounding electrode current crowding, ground potential rise fault and electromagnetic coupling faults

Modeling soil electrical conductivity under impulse discharge for electrical ground system

Soil electrical conductivity play an essential role in proper grounding system design for dissipation of static and dynamic electric charge. However, soil properties such as pH, moisture and nutrients causes’ non-linear variation in the soil electrical conductivity. This non-linear soil impedance phenomena directly affect electrical modeling of soil characteristics for efficient grounding system design. In this paper, the electrical dependency of soil properties on overall impedance have been investigated and used to formulate a soil impedance electrical circuit equation model through simulation and empirical methods. Electrical conductivity for samples of 30kg of soil with varying properties within at a moisture range of 14%-26% where injected with impulse discharge and the corresponding plot where fitted with electrical circuit simulation until a proper fit was achieved. The result shows that soil electrical impedance can be modeled with a complex circuit having both capacitive, resistive and inductive elements