129 articles for “Frequencies”

Research ArticleOpen accessIn the abstractThe Gaussianity Evaluations of Malaysian Stock Return VolatilityChin Wen CheongWe study the distribution of standardized returns by using various frequencies data. The empirical standardized returns are obtained by using the unobserved and observable daily volatility. Our empirical results evidence the realized-standardized returns follow nearest to a Gaussian distribution. On the other hand, the standardized returns using daily closing and range-based data are able to reduce but not fully eliminate … …American Journal of Applied Sciences, Vol. 5, Issue 2 · 28 Feb 2008 · 7,082 accessesView PDF Cite

Research ArticleOpen accessIn the abstractFPGA Based SPWM Bridge InverterM. N. Md Isa, M.I. Ahmad, Sohiful A.Z. Murad, M.K. Md ArshadThis study presents methodology to generate sinusoidal pulse width modulation (SPWM) signal using Field Programmable Gate Array, FPGA technology. We discussed the unipolar switching scheme and the methodology to generate the signal with the predetermined switching frequencies. Simulation on the designed pulses was conducted using Altera Max Plus II simulation tools. This simulation method was used to get the desired … …American Journal of Applied Sciences, Vol. 4, Issue 8 · 31 Aug 2007 · 7,399 accessesView PDF Cite

Research ArticleOpen accessIn the abstractAge Difference in Immunophenotype of Acute LeukemiaKazunori Nakase, Mary Sartor, Kenneth BradstockWe examined the immunophenotype of 880 cases with acute leukemia and analyzed their age difference in relation to the morphological subtype and the karyotype. We divided the patients into 3 age groups: child (0-15 years), adult (16-59 years) and elderly (60 years and older) group. The diagnoses based on the French-American-British (FAB) criteria and the immunophenotype as follows: 453 patients … …American Journal of Immunology, Vol. 2, Issue 3 · 30 Sep 2006 · 6,943 accessesView PDF Cite

Research ArticleOpen accessIn the abstractImproving Mechanical Characteristics of Inverter-induction Motor Drive SystemHussein Sarhan, Rateb IssaAn inverter-three-phase squirrel-cage induction motor drive system with improved mechanical characteristics is presented. The proposed system provides mechanical characteristics with constant maximum torque or increased maximum torque and reduced slip speed at frequencies below the nominal frequency. The control algorithm is based on the constant volts per hertz principle using two improvement techniques: keeping maximum torque constant or keeping magnetic … …American Journal of Applied Sciences, Vol. 3, Issue 8 · 31 Aug 2006 · 7,661 accessesView PDF Cite

Research ArticleOpen accessIn the abstractDetermination of Absorption Coefficients and Thermal Diffusivity of Modulated Doped GaAlAs/GaAs Heterostructure by Photothermal Deflection SpectroscopyS. Aloulou, M. Fathallah, M. Oueslati, A. SfaxiWe report in this study theoretical and experimental studies of photothermal deflection spectroscopy (PDS) for planar doped heterostructures AlGaAs/GaAs. The PDS spectra at T=300K are recorded by varying the wavelength of the excited radiation for different modulation frequencies. They show two different regions related to the fundamental electronic transitions from GaAs and Si doped AlGaAs. The DX levels have been … …American Journal of Applied Sciences, Vol. 2, Issue 10 · 31 Oct 2005 · 7,264 accessesView PDF Cite

Research ArticleOpen accessIn the abstractInduction of Micronuclei in Mice Lymphocytes Exposed to Microwave and TolueneS. B. Mortazavi, A. Safari, A. Khavanin et al.Increasing applications of microwave radiation are of great concern with regard to public health. Several studies have been conducted detect effects of microwave exposure genetic material leading to negative or questionable results. The Micronucleus (MN) assay which is proved to be a useful method for detection of radiation exposure-induced cytogenetic damage was used in the present study to investigate the … …American Journal of Applied Sciences, Vol. 2, Issue 9 · 30 Sep 2005 · 6,617 accessesView PDF Cite

Research ArticleOpen accessIn the abstractElectrochemical Characteristics of Some Purpurins in Aqueous and Nonaqueous SolutionsFarouk A. Rashwan, Hossnia S. Mohran, Ahmed A. El-SamahyThe Electrochemical Impedance Technique (EIS) and the Cyclic Voltammetric method (CV) were used to investigate the behavior of purpurin (P), Anthrapurpurin (AP) and Benzopurpurin (BP) in aqueous and in N, N-dimethylformamide (DMF) media. In the CV experiments, both the radical and the dianion of these substances were assumed to form of limited stability due to chemical protonation. In case of … …American Journal of Applied Sciences, Vol. 2, Issue 7 · 31 Jul 2005 · 6,744 accessesView PDF Cite

Research ArticleOpen accessIn the abstractEstimation of Vibrations in Switched Reluctance Motor DrivesS. Balamurugan, R. ArumugamThis study discusses a simple algorithm for estimation and reduction of Vibrations in a Switched Reluctance Motor (SRM) using magnetic circuit simulation in MATLAB/SIMULINK Environment. A Non-linear model is developed using magnetic circuit equations, wherein non-linearity is added using a inductance profile with back EMF. Dynamic characteristic of the SRM is simulated and the same is being verified experimentally. In … …American Journal of Applied Sciences, Vol. 2, Issue 4 · 30 Apr 2005 · 6,832 accessesView PDF Cite

Research ArticleOpen accessIn the abstractRevisiting the Unit Root Hypothesis and Structural Break: Asia and Emerging Economies Foreign Exchange MarketsChristopher Gan, Sirimon Treepongkaruna, Hue Hwa Au YongThis study examines the stationary of ten Asian and for emerging Foreign Exchange (FX) rates during the 1990s. The paper employs the Augmented Dickey-Fuller (ADF) unit root test to the following FX rates: Hong Kong Dollar (HKD) Japanese Yen (JPY), South Korean won (KRW) new Taiwan dollar (TWN), Chinese Renminbl (CHR), Indonesia Rupiah (IDR), Malaysian Ringgit (MYR), Singapore Dollar (SGD), … …American Journal of Applied Sciences, Vol. 1, Issue 1 · 31 Mar 2004 · 6,954 accessesView PDF Cite