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Accurate MATLAB Simulink PV System Simulator Based on a Two-Diode Model
Ishaque, Kashif,Salam, Zainal,Taheri, Hamed The Korean Institute of Power Electronics 2011 JOURNAL OF POWER ELECTRONICS Vol.11 No.2
This paper proposes a MATLAB Simulink simulator for photovoltaic (PV) systems. The main contribution of this work is the utilization of a two-diode model to represent a PV cell. This model is known to have better accuracy at low irradiance levels which allows for a more accurate prediction of PV system performance. To reduce computational time, the input parameters are reduced to four and the values of $R_p$ and $R_s$ are estimated by an efficient iteration method. Furthermore, all of the inputs to the simulator are information available on a standard PV module datasheet. The simulator supports large array simulations that can be interfaced with MPPT algorithms and power electronic converters. The accuracy of the simulator is verified by applying the model to five PV modules of different types (multi-crystalline, mono-crystalline, and thin-film) from various manufacturers. It is envisaged that the proposed work can be very useful for PV professionals who require a simple, fast and accurate PV simulator to design their systems.
Trends in Stroke Presentations before and during the COVID-19 Pandemic: A Meta-Analysis
Noman Ishaque,Asif Javed Butt,Joseph Kamtchum-Tatuene,Ali Zohair Nomani,Sarah Razzaq,Nida Fatima,Chetan Vekhande,Radhika Nair,Naveed Akhtar,Khurshid Khan,Maher Saqqur,Ashfaq Shuaib 대한뇌졸중학회 2022 Journal of stroke Vol.24 No.1
Background and Purpose There are reports of decline in the rates of acute emergency presentations during coronavirus disease 2019 (COVID-19) pandemic including stroke. We performed a meta-analysis of the impact of COVID-19 pandemic on rates of stroke presentations and on rates of reperfusion therapy. Methods Following the Meta-analysis Of Observational Studies in Epidemiology (MOOSE) guidelines, we systematically searched the literature for studies reporting changes in stroke presentations and treatment rates before and during the COVID-19 pandemic. Aggregated data were pooled using meta-analysis with random-effect models. Results We identified 37 observational studies (n=375,657). Pooled analysis showed decline in rates of all strokes (26.0%; 95% confidence interval [CI], 22.4 to 29.7) and its subtypes; ischemic (25.3%; 95% CI, 21.0 to 30.0), hemorrhagic (27.6%; 95% CI, 20.4 to 35.5), transient ischemic attacks (41.9%; 95% CI, 34.8 to 49.3), and stroke mimics (45.6%; 95% CI, 33.5 to 58.0)during months of pandemic compared with the pre-pandemic period. The decline was most evident for mild symptoms (40% mild vs. 25%–29% moderate/severe). Although rates of intravenous thrombolytic (IVT) and endovascular thrombectomy (EVT) decreased during pandemic, the likelihood of being treated with IVT and EVT did not differ between the two periods, both in primary and in comprehensive stroke centers (odds ratio [OR], 1.08; 95% CI, 0.94 to 1.24 and OR,0.95; 95% CI, 0.83 to 1.09, respectively). Conclusions Rates of all strokes types decreased significantly during pandemic. It is of paramount importance that general population should be educated to seek medical care immediately for stroke-like symptoms during COVID-19 pandemic. Whether delay in initiation of secondary prevention would affect eventual stroke outcomes in the long run needs further study.
Shehryar Ishaque,Naveed Ullah,Man-Hoe Kim 대한설비공학회 2022 대한설비공학회 학술발표대회논문집 Vol.2022 No.11
This study presents a parametric optimization of a microchannel gas cooler for a transcritical CO₂ mobile air-conditioning system. One of the main difficulties in selecting effective microchannel gas coolers for mobile air-conditioning systems is taking into account size, weight, and available space. One-dimensional, two-dimensional, or three-dimensional spatial restrictions are possible (i.e. the combination of length, height, and width). The height of the core is associated with the number of tubes, while the width of the core is associated with the number of ports. To study the simultaneous effect of a number of tubes, the number of ports in each tube, and tube length, different combinations were selected within the practical range to get an optimal dimension while keeping the total core volume constant. An optimal solution can be selected based on the maximum gas cooler capacity, minimum pressure drop, or the ratio of gas cooler capacity to pressure drop. One of the major concerns in the mobile air-conditioning system is a space limitation. Therefore, the current study focuses on the parametric optimization of a microchannel gas cooler based on the maximum heat exchanger capacity or minimum pressure drop concerning the available size and space.
Accurate MATLAB Simulink PV System Simulator Based on a Two-Diode Model
Kashif Ishaque,Zainal Salam,Hamed Taheri 전력전자학회 2011 JOURNAL OF POWER ELECTRONICS Vol.11 No.2
This paper proposes a MATLAB Simulink simulator for photovoltaic (PV) systems. The main contribution of this work is the utilization of a two-diode model to represent a PV cell. This model is known to have better accuracy at low irradiance levels which allows for a more accurate prediction of PV system performance. To reduce computational time, the input parameters are reduced to four and the values of Rp and Rs are estimated by an efficient iteration method. Furthermore, all of the inputs to the simulator are information available on a standard PV module datasheet. The simulator supports large array simulations that can be interfaced with MPPT algorithms and power electronic converters. The accuracy of the simulator is verified by applying the model to five PV modules of different types (multi-crystalline, mono-crystalline, and thin-film) from various manufacturers. It is envisaged that the proposed work can be very useful for PV professionals who require a simple, fast and accurate PV simulator to design their systems.
Fahmida Ishaque,Israt Jahan Ripa,Altaf Hossain,Abdur Rashid Sarker,Gazi Tamiz Uddin,Hafizur Rahman,Joyshankar Baidya 대한환경공학회 2021 Environmental Engineering Research Vol.26 No.1
Downscaling is a state-of-the-art technique to generate fine-resolution climate change prediction and an obvious tool for forecasting future climate scenarios for many data-scarce areas like Bangladesh. The Educational Global Climate Model (EdGCM) predicts numerically and its performance was not evaluated for Bangladesh earlier. Due to this reason, an attempt has been made to apply a new geostatistical approach with the help of transform software to downscale EdGCM for identifying the trend of surface air temperature at the Sylhet district. Both Doubled_CO₂ and Global_Warming_01 are simulated from EdGCM and maps are generated to depict global temperature variations. Downscaling is applied to the outputs from Doubled_CO₂ scenario. Percent of bias (PBIAS), Nash-Sutcliffe efficiency (NSE) and the ratio of root mean square error to the standard deviation of measured data (RSR) values are satisfactory and acceptable. The trend analysis was performed using the Mann-Kendall Trend test and Sen’s slope estimator. Temperature changes are significant for both downscaled and observed results of p-value which is less than alpha = 0.05. Mann-Kendall Z tests for annual downscaled and IPCC during (2006-2020) show a positive trend. Downscaled predicted annual average temperature (simulations by Doubled_CO₂) for 2020 is 21.67˚C for the Sylhet district.
Microchannel gas cooler simulation for transcritical CO2 cycle in automotive A/C systems
Naveed Ullah,Shehryar Ishaque,Man-Hoe Kim 대한설비공학회 2022 대한설비공학회 학술발표대회논문집 Vol.2022 No.11
This study aims to develop a microchannel gas cooler model for evaluating the performance of a transcritical CO₂ mobile air-conditioning system. A simulation model is developed using segment-by-segment approach in the MATLAB platform. The simulations are performed under different operating conditions and results are validated against the experimental data. Effect of different operating conditions including air and refrigerant inlet temperatures, flow rates, air velocity, and operating pressure on the gas cooler performance is studied. Results showed that the gas cooler capacity and refrigerant-side pressure drop are in good agreement with the experimental data within 4.29% and 8.88%, respectively.
Discretization of laser model with bifurcation analysis and chaos control
Qamar Din,Waqas Ishaque,Iqra Maqsood,Abdelouahed Tounsi Techno-Press 2023 Advances in nano research Vol.15 No.1
This paper investigates the dynamics and stability of steady states in a continuous and discrete-time single-mode laser system. By using an explicit criteria we explored the Neimark-Sacker bifurcation of the single mode continuous and discrete-time laser model at its positive equilibrium points. Moreover, we discussed the parametric conditions for the existence of period-doubling bifurcations at their positive steady states for the discrete time system. Both types of bifurcations are verified by the Lyapunov exponents, while the maximum Lyapunov ensures chaotic and complex behaviour. Furthermore, in a three-dimensional discrete-time laser model, we used a hybrid control method to control period-doubling and Neimark-Sacker bifurcation. To validate our theoretical discussion, we provide some numerical simulations.
Amjad, Muhammad,Salam, Zainal,Facta, Mochammad,Ishaque, Kashif The Korean Institute of Power Electronics 2012 JOURNAL OF POWER ELECTRONICS Vol.12 No.3
It is known that transformer based power supplies for ozone generators have low efficiency, high cost and exhibits a limited frequency range of operation. To overcome these disadvantages, this paper proposes a high frequency ozone generator with the absence of a transformer. The voltage step-up is achieved only by utilizing the resonant tank. This is made possible by a novel combination of ozone chamber materials that allow ozone to be generated at only 1.5 - 3.5 $kV_{p-p}$. The input to the resonant tank is driven by a PWM full bridge resonant inverter. Furthermore, zero-current zero-voltage switching (ZCZVS) operation is achieved by employing a duty factor of 25% between the switches of the full bridge. The advantages of the proposed system include high efficiency, low cost and the ability to control ozone production by varying the input voltage to the inverter. The prototype is verified by both simulation and experimental results.