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Sökning: WFRF:(Ahsan Nusrat)

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1.
  • Hoq, Md Tanbhir, et al. (författare)
  • Assessing Impact of Large Scale Integration of Wind and Solar PV Power Generation on Small Signal and Transient Stability
  • 2018
  • Ingår i: 4th International Conference on Electrical Engineering and Information & Communication Technology (iCEEiCT). - : IEEE. - 9781538682791
  • Konferensbidrag (refereegranskat)abstract
    • One imperative challenge in building a sustainable electricity future is to integrate renewable energy sources in the present energy mix. Renewable energy sources are inherently different in nature from their conventional counterparts. Thus integration to existing system posses a substantial challenges. In this paper using a IEEE 14 bus test system the effect of large scale and distributed integration of wind and solar PV on power system stability is assessed using PSAT. Both small signal and transient stability are studied with varying amount of renewable energy in the system. From the simulation results, it is observed that the small signal stability degrades with higher renewable energy penetration, and the transient frequency and voltage response of the system worsens as well with higher renewable energy in the system, but nonetheless the systems in different scenarios remains stable despite having poor damping.
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2.
  • Javed, Muhammad Sufyan, et al. (författare)
  • Electrochemical studies of perovskite cathode material for direct natural gas fuel cell
  • 2016
  • Ingår i: International journal of hydrogen energy. - : Elsevier. - 0360-3199 .- 1879-3487. ; 41:4, s. 3072-3078
  • Tidskriftsartikel (refereegranskat)abstract
    • Natural gas is the most promising renewable energy source and its widespread availability ensured its importance for early applications in stationary fuel cells as a reliable and low cost fuel. Therefore it is very important to efficiently utilization of natural gas in low temperature fuel cells. Herein, we demonstrate the synthesis of perovskite material of Yttrium doped Sr0.92FexTi1-xO3-delta (x = 0.25, 030) (YSFT) by solid state reaction method and further investigated as a new cathode material for a low temperature solid oxide fuel cell fueled by natural gas. The YSFT is characterized by X-ray powder diffraction, Brunauer-Emmett-Teller and scanning electron microscopy. The perovskite structure is achieved at relatively low temperature (850 degrees C). The average crystalline size is found 28 nm and 36 nm for x = 0.25 and 0.30 respectively. TGA results showed the lattice oxygen loss of YSFT is about 0.206% in its original weight in the temperature range of 25-1000 degrees C. The maximum electronic conductivities of 2.3 Scm(-1) and 2.07 Scm(-1) are achieved for x = 025 and x = 0.30 at 550 degrees C in air atmosphere respectively. It is observed that the oxygen reduction is enhanced due to the perovskite crystal structure and oxygen vacancies play an important role in the redox reaction to improve the performance of fuel cell. The YSFT perovskite cathode material based fuel cell with natural gas have achieved the power density of 250 mWcm(-2) for x = 025 at 550 degrees C. The fuel cell device has demonstrated very stable results by running continuously for 5 h with domestic available natural gas. 
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3.
  • Makhani, Naila, et al. (författare)
  • The diagnostic workup of children with the radiologically isolated syndrome differs by age and by sex
  • 2024
  • Ingår i: Journal of Neurology. - : Springer. - 0340-5354 .- 1432-1459.
  • Tidskriftsartikel (refereegranskat)abstract
    • Background: Cerebrospinal fluid (CSF) and spinal MRIs are often obtained in children with the radiologically isolated syndrome (RIS) for diagnosis and prognosis. Factors affecting the frequency and timing of these tests are unknown.Objective: To determine whether age or sex were associated with (1) having CSF or spinal MRI obtained or (2) the timing of these tests.Methods: We analyzed children (≤ 18 y) with RIS enrolled in an international longitudinal study. Index scans met 2010/2017 multiple sclerosis (MS) MRI criteria for dissemination in space (DIS). We used Fisher's exact test and multivariable logistic regression (covariates = age, sex, MRI date, MRI indication, 2005 MRI DIS criteria met, and race).Results: We included 103 children with RIS (67% girls, median age = 14.9 y). Children ≥ 12 y were more likely than children < 12 y to have CSF obtained (58% vs. 21%, adjusted odds ratio [AOR] = 4.9, p = 0.03). Pre-2017, girls were more likely than boys to have CSF obtained (n = 70, 79% vs. 52%, AOR = 4.6, p = 0.01), but not more recently (n = 30, 75% vs. 80%, AOR = 0.2, p = 0.1; p = 0.004 for interaction). Spinal MRIs were obtained sooner in children ≥ 12 y (median 11d vs. 159d, p = 0.03).Conclusions: Younger children with RIS may be at continued risk for misdiagnosis and misclassification of MS risk. Consensus guidelines are needed.
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