5kVa power inverter design and simulation based on boost converter and H-bridge inverter topology

Five (5) kVA power inverter was designed and simulated base on two topologies; Boost converter and Half-bridge inverter topology. A 555 timer IC was used as the control at fixed frequencies of 25 kHz and 50 Hz for the two stages. The results of the simulation were obtained. The graphs for both stages were plotted and the results show a significant increase in the voltage and duty cycle. The wave form of the output gives a square wave form. Keywords: Power inverter, Simulation, Topology, Converte

Risk factors and outcomes of ectopic pregnancies at Aminu Kano teaching hospital, Kano, Nigeria

Objectives: To determine the incidence, risk factors, clinical presentation, morbidity and mortality of ectopic pregnancies at Aminu Kano Teaching Hospital.Methods: It is a retrospective study of patients with ectopic pregnancies treated at Aminu Kano Teaching Hospital (AKTH), Nigeria, from 1st January, 2005 to 31st December, 2009. The record folders were retrieved from the record department of the hospital and analyzed using Epi Info Electronic statistical software. Data on socio-demographic characteristic, clinical features, postoperative outcomes and duration of hospital stay were extracted.Results: One hundred and ninety seven patients were admitted with ectopic pregnancy during the period under review. Their case notes were retrieved giving a retrieval rate of 91.14%. The mean age was 26.72 ± 5.20, the mean parity was 2.03 ±2.33. The major risk factors were past history of induced abortion (26.70%), and sexually transmitted infections (18.30%). Abdominal pains (93.30%), amenorrhoea (60.00%), vaginal bleeding (58.30%), abdominal tenderness (83.30%) and cervical motion tenderness (90.00%) were the major clinical features. The ampulla was involved in 58.33% of cases and salpingectomy was the surgical option in 95.56%. Shock (3.33%) and anaemia (3.33%) were the major complications.Conclusions: The incidence of ectopic pregnancy at Aminu Kano Teaching Hospital is 1.29%. The most important association is with pelvic infection. Therefore, efforts have to be emphasized on prevention, early and vigorous treatment of pelvic and sexually transmitted infections.Key Words: Ectopic pregnancy, Risk factors, Outcomes, Nigeria

Prevalence of malaria and practice of prevention among HIV positive pregnant women at Aminu Kano Teaching Hospital(AKTH), Kano)

A total of 360 primigravidae were studied at AKTH. 180 each of similar age and socioeconomic status were used as cases and controls in a prospective study. There was no statistically significant difference in their practice of malarial prevention at booking. The prevalence of malaria in their blood smears at booking was 32.22%, with the HIV infected cases accounting for23.33%, whilst the HIV uninfected accounted for 8.89%The prevalence of clinical malaria was significantly eight times higher and the prevalence of recurrent malaria was twenty six times higher in the HIV infected primigravidae as compared to the HIV uninfected primigravidae. Review of malarial prophylaxis in HIV infected primigravidae is recommended.Keywords: HIV infected, HIV uninfected, Malaria, Multigravidae, Primigravidae

Design and implementation of an android and web-based university timetable customization system

Timetabling is an essential component of scheduling in all sectors of education. University timetabling entails the scheduling of times and venues for lectures and examinations. These activities are logically structured in a time-wise manner and presented on papers and placed on notice boards in order to avoid conflicts of event. However, timetable schedule forgetfulness, misinterpretation, miscopying, cost of rescheduling and slow time to reach for the rescheduled timetables are the challenges posed by the use of paper and notice board-based timetables; hence, the need for automated timetables. In this paper, we discuss the implementation of Android and web-based timetable customization systems for the Faculty of Computer Science and Information Technology, Bayero University, Kano-Nigeria. The web-based system provides an administrative module that facilitates scheduling and rescheduling of lecture, examination and invigilation timetables. In addition, the Android timetable customization system permits the user to view, customize, set reminders and provide rescheduled timetable updates.Keywords: Android, Customization, Timetable and Web base

Comparitive study of electrical properties of carbon nano tube (CNT) and silicon nanowire (SNW) MOSFET devices

Metal oxide semiconductor field effect transistor (MOSFET) is a semiconductor device used in many electronic devices for amplification and switching electrical signals. MOSFET downscaling has been the driving force towards the technological advancement, but continuous scaling down of MOSFET causes problem of high power dissipation, high leakage current, Short Channel Effects (SCEs), excessive process variation and reliability issues. In this work, comparative study of electrical properties of carbon nanotube (CNT) and silicon nanowire (SWN) were carried out using CNT and SNW as channel materials, silicon dioxide as the gate dielectric, silicon substrate as base material. The analysis is carried out using FETTOY simulating software for oxide thickness (0.3,0.5,0.7,0.9 and 1.2nm). The results show that carbon nanotube channel material have highest transconductance (gm) of 1.00 x 10-4S, highest conductance (g4) of 4.00 x 10-6S, highest carrier injection velocity (vinj)of 5.43 x 10 5m/s, highest on current (Ion) of 59.79uA, at oxide thickness of 0.3nm when used as MOSFET device and improved short channel effects with subthreshold swing (S) of 67.79 mV/dec and drain induced barrier lowering (DIBL) of 39.67. More results such as drain current (Id) versus gate voltage ( Vg) , quantum capacitance (QC) versus gate voltage (Vg) , and average velocity of mobile electron versus gate voltage (Vg) for all devices are also investigated. Various results obtained indicate that CNT has the higher performance of decreasing gate capacitance with decrease in oxide thickness ( TOx) in deep nanometer regime. This decrease in gate capacitance is observed at a gate voltage of 0.5V and above which leads to the reduction of propagation delay, lower leakage current, low power dissipation, short channel effects (SCEs) as compared to silicon nanowire MOSFET device.KEYWORDS: Ballistic nanoscale MOSFET, Channel materials, FETTOY simulating software, Short channel effects (SCEs), Drain Induces Barrier Lowering (DIBL

A review on reversible logic gates

In recent years, reversible logic circuits have applications in the emerging field of digital signal processing, optical information processing, quantum computing and nano technology. Reversibility plays an important role when computations with minimal energy dissipation are considered. The main purpose of designing reversible logic is to decrease the number of reversible gates, garbage outputs, constant inputs, quantum cost, area, power, delay and hardware complexity of the reversible circuits. This paper reveals a comparative review on various reversible logic gates. This paper provides some reversible logic gates, which can be used in designing more complex systems having reversible circuits and can execute more complicated operations using quantum computers. Future digital technology will use reversible logic gates in order to reduce the power consumption and propagation delay as it effectively provides negligible loss of information in the circuit.   Keywords: Garbage output, Power dissipation, quantum cost, Reversible Gate, Reversible logic

Molecular Dynamics and Vibrational Analysis of Pentacene: RHF and DFT Study

The molecular dynamics of Pentacene molecule and its vibrational behavior is studied using the Gaussian software at the Restricted Hartree Fock and Density Functional Theory levels of computation. Two medium size basis sets, 6-31G and 6-31G* are used. The dipole moments, thermal energies and band gap computations for the molecule are obtained. The Infra Red (IR) and Raman vibrational frequencies are vividly examined and the most intense IR and Raman frequencies identified. The computed band gap at DFT level of theory for both basis sets is much in agreement with the experimental value. Keywords: Pentacene,  Hartree-fork, DFT, bond-angle, bondlength, Raman, frequencie

Energy Investigation Framework: understanding buildings from an energy perspective view.

According to the United Nations Global Status Report 2017, buildings and construction account for 36% of the global energy use and 39% of energy related carbon dioxide emissions [1]. A prudent design and accurate construction of energy efficient buildings are mandatory to reduce both global energy consumption and carbon dioxide emissions. The desired outcome can be achieved by (i) increasing the construction of low energy buildings, which are designed to sustain desired indoor temperature with a minimal energy input, (ii) and improving the energy performance of existing buildings. Some buildings underperform by gaining or losing more heat than needed. This study introduces a framework for investigating building energy performance. Thermography investigation, building modelling, characterization of thermal bridges and future prediction for overheating are encapsulated in the proposed framework. A sport changing facility, which was designed as a low energy building, serves as a demonstrator for the application of the framework. The energy investigation framework revealed that the facility is underperforming. According to the building model, the main reason for the poor building performance is thermal bridging (presence of steel members), which increases gas consumption and wall heat-loss by 18% and 11%, respectively. Other contributors to heat lose/gain are cracks in the building envelop, weak mortar joints and uninsulated hot water pipes. Furthermore, the future temperature data, which is input to the building model, suggests that the entire facility is under the risk of overheating

The Effect of Kelvin Effect on the Equilibrium Effective Radii and Hygroscopic Growth of Atmospheric Aerosols

In this paper we extracted microphysical properties of six types of atmospheric aerosols from Optical Properties of Aerosols and Clouds (OPAC) and numerically analyzed the analytical expressions for the changes in the equilibrium relative humidity (RH), effective radius, effective hygroscopic growth, the magnitudes and fractional changes in the effective radii  and the effective hygroscopic growth on the effects of surface tension (the Kelvin effect) on ambient atmospheric aerosols. The expressions were applied to two - one parameter models. We discovered from the analysis of the data extracted that, to the lowest order error, the change in the equilibrium RH, effective radii and effective hygroscopic growth depend on the compositions of the aerosols. From the two models used, we also discovered that the fractional changes in the ambient RH, effective radii and effective hygrosocopic growth, also depend on the aerosols compositions. Finally, we discovered that the magnitude of the Kelvin effect and its consequences on the atmospheric aerosols depend on the hygroscopicity of the aerosols. Keywords: Kelvin effect, effective radius, effective hygroscopic growth, atmospheric aerosols, ambient Relative Humidity