Investigating inter-turn fault in transformer using TTR and FRA

Transformers are one of the significant elements in the power system network. The Transformer function is to step up and down the voltages. When the transformer operating in high load, it exposes to failures. There are various transformer failures which could have a serious effect on the transformer efficiency. For example, winding deformation, tap changer damage, and short turns (inter-turn fault). The transformer inter-turns fault reduces the number of turns in the winding. To detect inter-turn fault, the transformer turn ratio test is the basic method used. On the other hand, frequency response analysis has been recognized to monitor the mechanical condition of the transformer winding. The frequency response analysis method can be conducted in four measurement connection. They are end to end open circuit test, end to end short circuit test, capacitive inter-winding, and inductive inter-winding. The inductive inter-winding low-frequency region is determined by the transformer turn ratio. This statement was mentioned in CIGRE A2.26. However, there are not approved studies on this issue. This study investigates the transformer inter-turn fault using transformer turn ratio test and frequency response analysis. In addition, this study performs various of statistical indicators on the FRA results. The statistical indicators are used to detect the variation between the normal and inter-turn fault responses. Also, this study proposes statistical indicators limits. After that compare the FRA and TTR results and check if the turn ratio results can be obtained using FRA inductive inter-winding test. Findings that FRA inductive inter-winding test can detect inter-turn fault. This can be determined by the absolute sum logarithmic error (ASLE), mean square error (MSE), and standard deviation (SD). Also, there are indicator limits has been proposed for ALSE and SD. This study finding helps to use the frequency response analysis method to replace the conventional turn ratio test

A novel steganography approach for audio files

We present a novel robust and secure steganography technique to hide images into audio files aiming at increasing the carrier medium capacity. The audio files are in the standard WAV format, which is based on the LSB algorithm while images are compressed by the GMPR technique which is based on the Discrete Cosine Transform (DCT) and high frequency minimization encoding algorithm. The method involves compression-encryption of an image file by the GMPR technique followed by hiding it into audio data by appropriate bit substitution. The maximum number of bits without significant effect on audio signal for LSB audio steganography is 6 LSBs. The encrypted image bits are hidden into variable and multiple LSB layers in the proposed method. Experimental results from observed listening tests show that there is no significant difference between the stego audio reconstructed from the novel technique and the original signal. A performance evaluation has been carried out according to quality measurement criteria of Signal-to-Noise Ratio (SNR) and Peak Signal-to-Noise Ratio (PSNR)

An Analysis of the Effects of Political Events on Oil Price Volatility and Consequential Spillover Effects on Selected GCC Stock Markets: An Emphasis on the Case of Kuwait

The purpose of this research is to identify how episodes of sustained market uncertainty due to political events can affect oil price behavior and potentially generate spillover effects to the stock markets of Kuwait, the Kingdom of Saudi Arabia (KSA) and the UAE. Three major events associated with significant levels of market uncertainty are examined: the Iraqi invasion of Kuwait in 2003, the Global Financial Crisis (GFC or the US Financial Crisis) in 2008, and the Arab Spring Revolution in 2011 – with the aim of identifying interlinkages between oil prices and the performance of the Kuwaiti, Saudi and the UAE stock markets. The study uses daily data collected from the Kuwait Stock Exchange (KSE), the Saudi Stock Exchange (TASI), the Abu Dhabi Securities Exchange (ADX), the Dubai Financial Market (DFM) and the United States Energy Information Administration (EIA) that were cross-checked with data available on DataStream. Well-known econometric models such as the Vector Autoregressive test, Cointegration tests (e.g. the Engle Granger and Johansen approaches), the Granger causality test and a more up to date model dealing with dynamic causality (frequency domain or spectral causality) were also implemented to help strengthen the research outcomes. The time period under study was conditioned to data availability issues and spanned between 1995 and 2016. The key research findings did not find significant evidence on the existence of a long run association between Brent oil prices and all four major stock price indices. The outcomes in the context of short run dynamics offered richer insights on regional dynamics. In the case of Kuwait, Granger causal effects from Brent returns to stock returns are reported for all cases except for the period of the Arab Spring Revolution. The results in the case of the KSA are similar to those registered for Kuwait with the exception of unidirectional causality running from stock returns to Brent returns during the US Financial Crisis. Dubai and Abu Dhabi exhibit a mixed type of behavior, as for example, in the case of Dubai no causal relationship is found during the Iraqi invasion and the US Financial Crisis. However, in the case of Abu Dhabi there is evidence of unidirectional causality running from Brent to stock returns during the GFC, while stock market returns signal a causal effect on Brent returns during the Arab Spring revolution. The outcomes for dynamic causality indicate that there is evidence of causal effects between the Kuwaiti stock market and Brent during early stages of the analyzed sample that connected to the Iraqi invasion period, and short run dynamics between Brent and stock returns during the GFC. In the case of the KSA, there is no evidence of dynamic causality running from Brent returns to stock returns. On the other hand, the dynamics are quite different when looking at stock returns causal effects on Brent returns, as evidence of a short run association is identified during the three shock events. In the case of the UAE, there is evidence of unidirectional causality from stock returns to Brent returns during the Iraqi invasion period. The outcomes for the volatility analysis (GARCH modeling) report stable results for the full sample period. However, when shock events are considered the GARCH model is not able to capture volatility effects and exhibits explosive behaviour for all countries and periods except for the case of Abu Dhabi, where the model remains stable during the Iraqi invasion and the Arab Spring revolution. The overall research findings indicate the existence of short-run dynamics between oil and the analysed stock markets in the Gulf Cooperation Council (GCC) region with lack of evidence on the existence of a long run relationship. The research outcomes from this thesis are significant for market players, governments and policy makers who should consider monitoring closely the relationship between oil and stock markets in the GCC region, as they are exhibiting dynamic behaviour in a context of oil dependent economies

Online Questionnaire Data Analysis System (OQDAS)

The aim of this project is to develop an Online Questionnaire Data Analysis System (OQDAS) for researchers in University Utara Malaysia. This system enables research questionnaires to be deployed via a web page and provide a great source of information to all UCTM researchers. By developing this project, it helps the researcher to perform survey easily, cost-effectively, and time shortly. In addition, analytical results reported in PDF file automatically. As well, a prototyping as a part of the traditional SDLC approach will be chosen as a guide to develop OQDAS

Immigrant Learning in Community Colleges: Unpacking Student Experiences in Minnesota

This study explored lived experiences of Somali immigrant students as they studied at a community college in Minnesota. Although, many Somalis are pursuing educational opportunities in MN community colleges. Little research is available on their community college experiences. The aim of this study was to extend the limited research on Somali immigrant students by providing valuable information regarding their community college experiences. A qualitative study design with a phenomenological approach was employed to examine the lived experiences of six students who participated in semi-structured focus group and individual interviews. Findings of the study show that Somali students face many challenges in the community college setting. Challenges such as language barriers, financial constraints, family and work obligations, struggle with online learning and culture shock/acculturation. Based on the findings, it is clear that more should be done to ease such obstacles for immigrant students in MN community colleges

Enhancing the BER and ACLR for the HPA Using Pre-Distortion Technique

Power amplifiers are key components in wireless transceivers. Their function is to amplify signal and generate the required Radio Frequency (RF) power that allows to transmit the signal over an appropriate range. The Orthogonal Frequency Division Multiplexing (OFDM) systems are highly sensitive to nonlinear distortion introduced by High Power Amplifier (HPA). The HPA nonlinearity causes in-band and out-of-band distortions. The linearization techniques are used to compensate the nonlinear effects of the high power amplifier. These techniques correct the distortion effects resulting from nonlinearities in the transmitted signal. Many linearization techniques have been developed to improve power amplifier linearity and to decrease both Bit Error Rate (BER) and Adjacent Channel Leakage Ratio (ACLR). This work is set to run the high power amplifier in the nonlinear region. It is also attempting to analyze the resulting signal in terms of the BER and ACLR, next employs pre-distortion linearization techniques to reduce the distortion introduced in this region. According to Digital Video Broadcasting-Terrestrial (DVB-T) standard the linearization techniques, circuit and the OFDM transmitter and receiver is designed and implemented through using computer simulation of AWR Design Environment

Preparing New Ceramic Membranes from Syrian Zeolite Coated with Silver Nanoparticles to Treatment Wells Water

نتيجة لتفاقم مشكلة تلوث المياه اتجهت الابحاث نحو دراسة المعالجة باستخدام الاغشية السيراميكية التي أثبتت فعالية عالية في معالجة كافة مصادر المياه, يهدف البحث لدراسة امكانية تحضير نوع جديد من الأغشية السيراميكية من الزيوليت السوري غير المستخدم سابقاً في هذا المجال. تم في هذا البحث تحضير أغشية سيراميكية من الزيوليت السوري الخام على عدة مراحل، حيث تم توصيف عينة الزيوليت وطحنها ومزجها بحمض البور, ثم ضغطت لتشكيل أقراص, عولجت حرارياً حسب برنامج حراري تجريبي, تم تغليفها أخيراً بجسيمات الفضة النانوية. تم تحديد مواصفات الأغشية المحضرة وفقاً للطرق المرجعية، تم اختبار فعالية الأغشية المحضرة في معالجة مياه الآبار، رشحت عينة الماء من خلال أغشية محضرة، ثم تم توصيفها بعد المعالجة. أظهرت النتائج أن أغشية الزيوليت المحضرة كانت ذات فاعلية عالية من خلال تقليل الملوثات الكيماوية والميكروبية, حيث انخفض COD إلى 96.9٪ ، BOD إلى 95.45٪ ، العكارة إلى 90٪ ، المواد الصلبة الذائبة إلى 59.66٪ ، كان هناك انخفاض مهم في التعداد العام للبكتيريا بعد المعالجة فكانت بنسبة النمو 0٪ تقريبًا على الوسط من النوع MAC ، لذلك كانت درجة الإزالة 100٪ ، بينما كانت درجة الإزالة 97٪ للسلالات البكتيرية على الوسط PCA، و 93٪ في الوسط من النوع PDA. وهذا يحقق المواصفة القياسية السورية لمياه الشرب رقم 45 لعام 2007 تم تحديد مواصفات الأغشية المحضرة وفقاً للطرق المرجعية ، وتم اختبار فعالية الأغشية المحضرة في معالجة مياه الآبار ، تم ترشيح عينة الماء من خلال أغشية معدة ، ثم تم توصيفها بعد المعالجة.أظهرت النتائج أن أغشية الزيوليت المحضرة كانت عالية الفعالية من خلال تقليل الملوثات الكيماوية والميكروبية والتي كانت مطابقة للمواصفة القياسية السورية / 45/2007.As a result of the exacerbation of the problem of water pollution, research was directed towards studying the treatment using ceramic membranes, which proved to be highly effective in treating all water sources. The research aims to study the possibility of preparing a new type of ceramic membranes from Syrian zeolite that was not previously used in this field. In this research, ceramic membranes were prepared from Syrian raw zeolite in several stages. Zeolite sample was characterized, grinded, mixed with boric acid, pressed to form desks, treated thermally according to experiment program, finally coated with silver nanoparticles. Specifications of prepared membranes were determined according to reference methods, effectiveness of prepared membranes were tested in well water handling, that water sample was filtrated through prepared membranes, and then it   type MAC, so removal degree was 100%, While removal degree was 97% for bacterial strains on Agar with type PCA, 93% on Agar with type PDA which were conformed to Syrian standard /45 /2007. Specifications of prepared membranes were determined according to reference methods, effectiveness of prepared membranes were tested in well water handling, that water sample was filtrated through prepared membranes, then it was Characterized after treatment. Results showed that prepared zeolite membranes were high effectiveness through decrease chemical and microbial pollutants which were conformed to Syrian standard /45 /200

High frequency link Uninterruptible Power Supply (UPS) system

This thesis was submitted for the degree of Master of Philosophy and awarded by Brunel University.The main aim of this thesis is to propose, design, simulate and build a new UPS system which can be used for compact applications. The idea of the proposed system is to operate the transformers within the UPS at high frequency so that the size and the weight are kept to minimum. In order to achieve this aim, the transformer within the UPS system is operated at high frequency; however it also carries two 50 Hz waveforms at 180 phase shift so that the transformer does not see this 50 Hz frequency. A cycloconverter is then used to reconstruct the 50 Hz waveform for the UPS output. The UPS system is simulated using PSPICE software at high frequency link of 500 Hz, 1 kHz, 5 kHz and 10 kHz. The simulation results show that the transformer only passes the high frequency component while the 50 Hz frequency is ‘hidden’ within the transformer. The proposed UPS system is then built using MOSFETs IRF740 as the main switches for the inverter and cycloconverter circuits. A Chipkit-uno32-development-board is used to control the MOSFET switches. Simulated and practical results show the viability of the proposed UPS system.This study is funded by Dubai Aluminium

Studying the effect of concentration on spectral and optical properties of chitosan polymer

Due to its noteworthy physico-chemical behaviors, the chitosan (CS) biopolymer presents a compelling alternative to conventional biomaterials. By measuring the emission spectra at a spectrofluorophotometer in different concentrates (1x10-4, 1x10-5, and 1x10-6) M, the spectral characteristics of the CS polymer were obtained. The crystallinity of the CS polymer was determined by X-ray diffraction (XRD) analysis, which shows only one dominant peak indexed to the orthorhombic structure. With a drop in solution concentration, there was a shift toward the shorter wavelength and a decline in quantum yield. Using a UV-Vis spectrophotometer, the optical properties of the CS polymer, including its refractive index, absorption coefficient, energy band gap, extinction coefficient, and dielectric constant, have been studied. It was observed through the results that the optical parameters are linearly dependent with concentration. In contrast to the optical energy gap, which decreases with increasing concentration

Aquasomes as a drug delivery system for proteins and peptides

Aquasomes are nanocarrier systems consist of three distinctive layers; an inner core, a polyhydroxy carbohydrate layer and an outer layer of an API (Kossovsky et al., 1991). Aquasomes have a unique structure and ability to carry active molecules through a non-covalent bounding and provide superior stability, especially for proteins and peptides (Masatoshi and Yongning, 1998; Kim and Kim, 2002; Khopade et al., 2002). Different core and coating materials were used to prepare aquasomes under different conditions to investigate the relationship between preparation conditions and loading efficiency. In terms of loading efficiency, hydroxyapatite aquasomes, with either lactose or trehalose as a coating material, had the highest BSA loading (40%-60%) when compared to DSPA aquasomes. While DCPA aquasomes, with either lactose or trehalose as a coating material, had the lowest BSA loading (8%-16%). To investigate the interaction of the three layers of aquasomes, Surface analysis, docking and MD simulations were performed. Surface analysis performed by Discovery Studio showed that HA and trehalose interact by hydrogen bonding with the later acting as a hydrogen acceptor, while BSA displayed almost complete SAS and that there are numerous targets for trehalose attachments (no specific active site). MD simulations of BSA performed by AMBER 12 showed a stable MD simulation of BSA for 5 ns. Total energy analysis of BSA on the two conditions performed (300K and 280K) support the experimental data of lower BSA loadings of aquasomes prepared at 400C compared to those manufactured at 250C (p5.5 and steadily release for 6 hr. Cell culture studies were conducted to demonstrate the controlled release effect of aquasomes using Caco-2 cell lines. The release of metronidazole (model drug) from aquasomes post 2 hr started to slow gradually until it reached its highest difference at 6 hr (p<0.05) when compared to the control