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A Novel Pulse-Width and Amplitude Modulation (PWAM) Control Strategy for Power Converters
Ghoreishy, Hoda,Varjani, Ali Yazdian,Farhangi, Shahrokh,Mohamadian, Mustafa The Korean Institute of Power Electronics 2010 JOURNAL OF POWER ELECTRONICS Vol.10 No.4
Typical power electronic converters employ only pulse width modulation (PWM) to generate specific switching patterns. In this paper, a novel control strategy combining both pulse-width and amplitude modulation strategies (PWAM) has been proposed for power converters. The Pulse Amplitude Modulation (PAM), used in communication systems, has been applied to power electronic converters. This increases the degrees of freedom in eliminating or mitigating harmonics when compared to the conventional PWM strategies. The role of PAM in the novel PWAM strategy is based on the control of the converter's dc sources values. Software implementation of the conventional PWM and the PWAM control strategies has been applied to a five-level inverter for mitigating selective harmonics. Results show the superiority of the proposed strategy from the THD point of view along with a reduction in the inverter power dissipation.
A Novel Pulse-Width and Amplitude Modulation (PWAM) Control Strategy for Power Converters
Hoda Ghoreishy,Ali Yazdian Varjani,Shahrokh Farhangi,Mustafa Mohamadian 전력전자학회 2010 JOURNAL OF POWER ELECTRONICS Vol.10 No.4
Typical power electronic converters employ only pulse width modulation (PWM) to generate specific switching patterns. In this paper, a novel control strategy combining both pulse-width and amplitude modulation strategies (PWAM) has been proposed for power converters. The Pulse Amplitude Modulation (PAM), used in communication systems, has been applied to power electronic converters. This increases the degrees of freedom in eliminating or mitigating harmonics when compared to the conventional PWM strategies. The role of PAM in the novel PWAM strategy is based on the control of the converter’s dc sources values. Software implementation of the conventional PWM and the PWAM control strategies has been applied to a five-level inverter for mitigating selective harmonics. Results show the superiority of the proposed strategy from the THD point of view along with a reduction in the inverter power dissipation.
Seyed Mojtaba Ghoreishy,Sheida Zeraattalab-Motlagh,Reza Amiri Khosroshahi,Amirhossein Hemmati,Morvarid Noormohammadi,Hamed Mohammadi 한국임상영양학회 2024 Clinical Nutrition Research Vol.13 No.3
Meta-analyses have been conducted with conflicting results on this topic. Due to missing several eligible studies in previous meta-analysis by Lam et al., we conducted an extensive systematic review and dose-response meta-analysis of randomized controlled trials in this regard. A comprehensive search was conducted across various databases, including MEDLINE/PubMed, ISI Web of Knowledge, Scopus, and Google Scholar, until November 2023. Based on the analysis of 33 studies comprising 2,047 individuals, it was found that there was a significant increase in body weight for each 1 g/day increase in omega-3 lipids (standardized MD [SMD], 0.52 kg; 95% confidence interval [CI], 0.31, 0.73; I2 = 95%; Grading of Recommendations Assessment, Development and Evaluation [GRADE] = low). Supplementation of omega-3 fatty acids did not yield a statistically significant impact on body mass index (BMI) (SMD, 0.12 kg/m2; 95% CI, −0.02, 0.27; I2 = 79%; GRADE = very low), lean body mass (LBM) (SMD, −0.02 kg; 95% CI, −0.43, 0.39; I2 = 97%; GRADE = very low), fat mass (SMD, 0.45 kg; 95% CI, −0.25, 1.15; I2 = 96%; GRADE = low), and body fat (SMD, 0.30%; 95% CI, −0.90, 1.51; I2 = 96%; GRADE = very low). After excluding 2 studies, the findings were significant for BMI. Regarding the results of the dose-response analysis, body weight increased proportionally by increasing the dose of omega-3 supplementation up to 4 g/day. Omega-3 fatty acid supplementation can improve body weight, but not BMI, LBM, fat mass, or body fat in cancer patients; large-scale randomized trials needed for more reliable results.
Non-parametric comparison and classification of two large-scale populations
Ghoreishi S. K.,Wu Jingjing,Ghoreishi Ghazal S. 한국통계학회 2023 Journal of the Korean Statistical Society Vol.52 No.1
In this paper, we investigate a non-parametric approach to compare two groups in microarray data. This is done using a threshold penalized-distance likelihood function, which is made up of a penalty and a suitable threshold distance, and is applicable when sample size is small or when the data is not normally distributed. We also use this function to classify new data. This is based on objects that are identified as differences between the two groups, not for all objects. We also study a real data application to illustrate our methods.
Empirical estimates for heteroscedastic hierarchical dynamic normal models
Ghoreishi S. K.,Wu Jingjing 한국통계학회 2021 Journal of the Korean Statistical Society Vol.50 No.2
The available heteroscedastic hierarchical models perform well for a wide range of real-world data, but for data sets that exhibit a dynamic structure they seem fit poorly. In this work, we develop a two-level dynamic heteroscedastic hierarchical model and suggest some empirical estimators for the association hyper-parameters. Moreover, we derive the risk properties of the estimators. Our proposed model has the feature that the dependence structure among observations is produced from the hidden variables in the second level and not through the observations themselves. The comparison between various empirical estimators is illustrated through a simulation study. Finally, we apply our methods to a baseball data.
Ghoreishi, Sayed Mehdi,Naeimi, Hossein,Navid, Mohammad Davodi Korean Chemical Society 2005 Bulletin of the Korean Chemical Society Vol.26 No.4
The interaction between ionic surfactants and different nonionic molecules and polymers are studied using ion surfactant selective electrode. From the experimental data, critical concentrations of the interaction and binding process are evaluated. The interaction between hexadecyltrimethylammonium bromide (HTAB) with polyethylene glycol (PEG) in three molecular weights (1000, 10000 and 100000) and also schiff-bases, 2-[2-carboxyphenyl nitrilomethylidyne]-phenol (ortho CNP), 2-[3-carboxyphenyl nitrilomethylidyne]-phenol (meta CNP)and 2-[4-carboxyphenyl nitrilomethylidyne]-phenol (para CNP) with the potentiometric method were investigated using HTAB membrane selective electrode. In the case of PEG with increasing molecular weights more interaction to HTAB occurs. The electromotive force (EMF) data also showed that interaction between para CNP with HTAB is more than the other schiff-bases. It seems this case related to less space interference of COOH group for that compound. The onset of binding ($T_1$) of course is the same for three schiffbase molecules.
Contribution of Thermal Mass to Energy Performance of Buildings: A Comparative Analysis
Ghoreishi, Amir H.,Ali, Mir M. Sustainable Building Research Center 2011 International journal of sustainable building tech Vol.2 No.3
Concrete has structural, architectural, and environmental applications in buildings. As one of its advantages, the thermal mass property of concrete plays an important role in a building's energy performance and reduces heating and cooling loads. In this paper, results of an investigation of the effect of thermal mass of concrete on a building's energy consumption in comparison with steel and masonry are presented. For the purpose of this research, three major parameters including height, occupancy, and location of buildings in six US climate zones were considered and maximum cooling load was chosen as the main measuring index of building energy performance. The results have shown that in residential and commercial buildings, the thermal mass property of concrete could reduce the maximum cooling load by 7% to 10%. Office and commercial buildings in Phoenix, AZ and residential buildings in Fargo, ND have shown the highest cooling load reduction of nearly 10% compared with other studied locations. Furthermore, as expected, concrete and masonry have exhibited better thermal mass performance than steel.
Sayed Mehdi Ghoreishi,Hossein Naeimi,Mohammad Davodi Navid 대한화학회 2005 Bulletin of the Korean Chemical Society Vol.26 No.4
The interaction between ionic surfactants and different nonionic molecules and polymers are studied using ion surfactant selective electrode. From the experimental data, critical concentrations of the interaction and binding process are evaluated. The interaction between hexadecyltrimethylammonium bromide (HTAB) with polyethylene glycol (PEG) in three molecular weights (1000, 10000 and 100000) and also schiff-bases, 2-[2-carboxyphenyl nitrilomethylidyne]-phenol (ortho CNP), 2-[3-carboxyphenyl nitrilomethylidyne]-phenol (meta CNP)and 2-[4-carboxyphenyl nitrilomethylidyne]-phenol (para CNP) with the potentiometric method were investigated using HTAB membrane selective electrode. In the case of PEG with increasing molecular weights more interaction to HTAB occurs. The electromotive force (EMF) data also showed that interaction between para CNP with HTAB is more than the other schiff-bases. It seems this case related to less space interference of COOH group for that compound. The onset of binding (T1) of course is the same for three schiff-base molecules.
Seyyed Mohammad Ghoreishi,Ehsan Bataghva 한국화학공학회 2014 Korean Journal of Chemical Engineering Vol.31 No.9
Mathematical modeling of supercritical CO2 extraction of essential oil from Echium amoenum seed wascarried out. The effect of process variables such as pressure (15, 20, 25 and 30 MPa), temperature (313, 318, 323 and328 K) and CO2 flow rate (0.6, 0.9, 1.2 and 1.5 ml/min) on the recovery of essential oil extraction was investigatedin a series of experiments conducted in a laboratory scale apparatus. The chemical composition of recovered essentialoil (fatty acids) was analyzed by GC-FID. The mathematical model was developed utilizing diffusion-controlled regimein the pore and film mass transfer resistances with axial dispersion of the mobile phase at dynamic conditions. Henry’slaw was used to describe the equilibrium state of solid and pore fluid phases. The obtained mass transfer equationsfor the mobile and stationary phases were solved using the numerical explicit method of line, and the modeling pre-dictions of oil extraction recovery were validated via comparison with experimental data. Genetic algorithm (GA) wasapplied to estimate the optimum value of the Henry constant. Finally, applying the validated model the extraction re-covery was investigated as a function of effective variables such as dynamic extraction time and supercritical fluidtemperature, pressure and flow rate. A set of optimal operating conditions were determined via modeling parametricanalysis to achieve the objective function of maximum recovery.
Rajabi, Leila,Ghoreishi, Majid The Korean Welding and Joining Society 2017 대한용접·접합학회지 Vol.35 No.1
In this study, the volumetric heat source in electron beam welding (EBW) is modeled through finite element method taking advantage of ABAQUS software package. Since this welding method is being applied in plates with different thicknesses and also considering that residual stresses reduce the strength of these weldments, the effect of thickness in the distribution and magnitude of residual stresses after welding is studied. Regarding the vast application of Inconel 706 super-alloy in aerospace industries, this material was selected in the current research. In order to validate the finite element model, the obtained results were compared to those of other researchers in this area, and good agreement was observed. The simulation results revealed that increase in the plate thickness leads to increase in the residual stresses. In addition heat treatment in the base metal (before welding) increases the residual stresses significantly.