European Journal of Scientific Research
Volume 136 No 4
Variable Frequency Carrier Band PWM Switched MLI for a Three Phase Induction Motor
R.Geetha and M.Ramaswamy
The paper arbitrates the theory of a variable frequency carrier based pulse width modulation strategy to generate the firing pulses for the switches in a series parallel switched cascaded multilevel inverter. It allows the multilevel inverter to offer a variable voltage for the three phase induction motor. The variation in the carrier wave frequency encompasses the sinusoidal reference to mitigate the higher frequency components of the output voltage and contribute to an increase in its fundamental constituent along with a lowering of its total harmonic distortion. The MATLAB based simulated response ordains the flexibility of the choice of a target voltage and augurs the motor to operate at the speed in accordance with the utility requirements. The results enliven its ability for its use in industrial entities in light of its resurgent claim to obviate the performance of multicarrier pulse width modulation strategy.
Keywords: Variable frequency carrier pulse width modulation, Induction motor , Total harmonic distortion , Series parallel switched cascaded multilevel inverter, Phase disposition.
Characterisation and Evaluation of Fly Ash at Higher Fineness Levels
S K Chaturvedi and A K Sahu
The objective of this study is to investigate the properties of fly ash at the microscopic level after prolonged grinding, particularly changes occurring in its fineness levels, specific gravity, particle size distribution, morphology, type of glass grains and their fracture mechanism, glass distribution and its content. Study revealed that fragmentation of Si-rich glass grains was increased with increased grinding time. The agglomeration of Si-rich glass grains started after 150 minutes and became prominent after 510 minutes of grinding. While, Fe-rich glass grains remained intact even after prolonged grinding, Si-rich glass grains were not further ground beyond 3 micron. SEM-EDAX analysis of fly ash sample after 720 minutes of grinding indicated that SiO2 content in the broken glass grains decreased and the Al2O3 content increased. Such changes in glass content and its chemistry play an important role in the reactivity of fly ash when used in cement.
Performance investigation of a Wickless Heat Pipe Parabolic Trough Solar Collector
Muhammad Asmail Eleiwi, Dr.Fayadh Mohammed Abed and Dr. Ahmed Abed Mohmed Saleh
The overall system performance of wickless heat pipe(thermosyphon) parabolic trough solar collector with evacuated glass tube and with tracking system has been investigated experimentally. It was used distilled water as a working fluid with filling charge ratio 50% inside heat pipe. The advantage of this system is high effective thermal conductance, solving the problems of flat-plate solar water heaters including (corrosion, cycle reversing, and freezing). In addition the use of the heat pipe technology in solar collectors will not only solve these problems but also eliminate the effect of the daily and seasonal variation of the solar radiation on the collector performance. The objective of the current study is to find out the effect of presence and absence of load in the case of pumping on and pumping off. The results show that the overall system performance at no-load in both cases are 13.65% and 13.55% respectively. Whereas, at the load (0.0034kg/sec) in both cases are 20.77% and 20.28% respectively. These results show that the overall system performance at the load are greater than at no-load, also the results show the increase in load lead to increase the overall system performance.
Keywords: Parabolic collector, wickless heat pipe, filling charge ratio
Recent Progress in Tribological Behaviors Of Nitride Treated Austenitic Stainless Steel- A Review
Austenitic stainless steel has excellent corrosion resistance and, therefore, it is used in chemical, food, medical, nuclear industries, etc. However, when it slides against itself, it exhibits severe metallic wear, surface damage and subsurface plastic deformation because of strong adhesive bonds at the contact junctions. Furthermore, austenitic stainless steel exhibits poor tribological properties. Hence, its surface has to be surface treated properly. The surface modification does not only solve component degradation problems but also can provide added value. Although all kind of coating method is in practice, diffusion coating is widely used and has many advantages as follows: (1) coating adhesion strength is very high, (2) fine surface structure can be obtained, (3) there is no or negligible amount of dimensional changes occur, (4) diffuse coated components can be directly used, (5) coating retains the basic property of bulk material. Hence, in this paper, a detailed review has been done on nitride treated stainless steel and its tribological properties are discussed.
Synthesis and Characterization of New Azo Dye Ligand Derived from 4,4'-Sulfonyl Dianiline and 4,5-Diphenyl Imidazole and its Binuclear Complexes with Cu(II) and Pd(II)
Sajid M.Lateef, Hussein K.AL-Hakeim and Noor Al-Huda Basim
The new azo ligand has been synthesised via reaction of 4,5-diphenyl imidazole
and 4,4’-sulfonyl dianiline
. This ligand has been characterized by different techniques such as, (IR, U.V-Vis) spectroscopy, (1
C) NMR spectra, GC-Mass spectrum and micro-elemental analysis. Its Cu(II) and Pd(II) binuclear complexes were prepared and characterized by (IR, U.V-Vis) spectroscopy, GC-Mass spectrum, micro-elemental analysis, magnetic susceptibility, conductivity measurements, mole ratio study and atomic absorption. The ligand acts as binuclear and bidentate at the same time with (N,N) set donar and coordinates through nitrogen atom from azo group and nitrogen atom from imidazole ring . Octahedral geometry structure proposed to Cu(II) complex, while square planar structure was proposed for Pd(II) complex.
Keywords: 4,4'-sulfonyl dianiline
, binuclear complexes, Cu(II) and Pd(II) ions, 4,5-diphnyl imidazole, Mass spectrum.
The Effect of Economic and Financial Factors on the Wheat Prices
The aim of this study is to reveal the determinants of wheat prices using daily data over the period of January 1st, 2003 to April 30th, 2014. In particular, five variables were taken into account, namely oil, bond value, gold, Dow Jones Industrial Average (DJIA) and Baltic Dry Index (BDI). The GJR – GARCH results showed a positive effect of oil, gold, DJIA and BDI on wheat prices, while bond affects negatively the wheat prices. Moreover, the study reveals that the wheat market is inefficient. Finally, the structural analysis of volatility with the GJR-GARCH model has shown that the current volatility is more influenced by the past volatility rather than by the previous day shocks.
Keywords: GARCH, Wheat, Oil, Bon value, Gold, Dow Jones Industrial Average, Baltic Dry Index.
A Novel Method for Hiding Sensitive Association Rule using Genetic Approach.
Kasthuri S and Meyyappan T
Data mining helps us to sift out precious information from masses of data. It also helps in discovering patterns from large datasets. Association rule mining finds frequent patterns among sets of items in data repositories. As there are more advancement in network and data mining techniques, the more critical it becomes to secure the privacy of sensitive information when releasing data to third parties. Association rule hiding comes handy here to enable privacy preservation. It preserves the sensitive association rules by modifying transactions in the database. These modifications will generate the side-effects such as lost and ghost rules which make database utilization worse. The sensitive rules that are hidden and the generated side effects have a tie-over. In this research, a novel method based on genetic approach is proposed for hiding the sensitive association rules. This approach minimizes the side effects of lost and ghost rules and supports security and utilization of datasets like military, medical and business datasets. The first phase of this two-phased method suggests the sensitive rules are used as the input for the second phase. The second phase modifies the transactions in order to hide the sensitive rules. This method is implemented in java. Experimental results are plotted. The results show that previous works are outperformed in terms of side effects generated.
Keywords: Association Rule Hiding, Data Mining, Privacy Preserving Data Mining, Genetic Algorithm, Sensitive
The Moderating Effect of Individual Culture Orientation on the Relationship between Leadership Styles with Perceived Employees Performance
JAVERIA BAIG, ALI ABUSALAH ELMABROK MOHAMMED, NG KIM SOON, YASIN MUNIR and SAIDA BAIG
The purpose of this study is to examine the relationship of leadership styles and perceived employee performance and further explores the moderating effect of individual culture orientation, such as power distance, uncertainty avoidance, masculinity and individualism on the relationship of transformational leadership and perceived employee performance in banking sector of Pakistan. This empirical study explains the role of two types of leaders, transformational leader who unite the interests of the organization and its members, in contrast with the transactional leader who practice contingent reinforcement of followers. Transformational leadership styles build on the transactional base in contributing to the extra effort and performance of followers. Therefore, the study also examines that which leadership style is more authentic and influential. Data from 127 subordinates indicates the significant and positive association of transformational and transactional leadership with perceived employee performance. In addition, results indicate that transformational leadership has stronger and positive associations with perceived employee performance. Regarding the moderating effects of culture orientation, overall data show significant influence on the relationship of leadership styles and perceived employee performance. The findings have important implications for the organization and leadership literature.
Keywords: Banks, Transformational leadership, transactional leadership, individual culture orientation, firm performance.
Spray pyrolysis deposition of thin films: Review
Spray pyrolysis method has been used for the preparation of various types of thin films such as binary, ternary and quaternary compounds. It is simple, cost effectiveness and no high temperatures are required during processing. The effect of deposition parameters on the properties of films was investigated. The obtained films were characterized using various analysis methods and were discussed in this work.
Keywords: Spray pyrolysis, thin films, semiconductor, solar cell, chalcogenide.
Asymmetric Oil Market. Linking Energy with Other Basic Indicators and Commodities
Giorgos Galyfianakis, Alexandros Garefalakis, Christos Lemonakis and Zanidakis Nikolaos
Oil prices have been analyzed for decades and attract special attention from both, academics and market participants, for many years. During the last decade and especially after the global economic crisis of 2008, energy market- dominated by crude oil- exhibits a noticeable price volatility with great impact to both investor's behavior and financial or commodity markets. It is well documented by the literature that oil price shocks affect the real economy but relatively less work has be done, using recent data, connecting oil prices, industrial production, and other financial indicators and basic commodities. The purpose of this paper is to explore the effects of some basic commodities (gold, silver, metals) and financial markets (bonds) and indicators (industrial production) on the energy (crude oil) market.
During our research and while modeling oil price volatility, there were evidence for the presence of ARCH and GARCH effects respectively indicating the percentage change of the oil price over the sample estimation period. Consequently, since the estimated coefficients for the ARCH and GARCH effects were substantially lower than unity, it follows that shocks to the conditional variance of the percentage change of oil price will not be persistent. Finally, our results indicate that oil price volatility increases more after a large negative shock than after a large positive shock confirming the relevant literature on this subject.
Keywords: Energy Market, Crude Oil, GARCH, GJR-GARCH.
JEL: G1; C1; Q4