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Performance improvement of complementary feeders using static transfer switch system

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2009年第2期10卷 189-200页

作者： Tahir mahmood Mohammad Ahmad CHOUDHRY Department of Electrical Engineering University of Engineering and Technology

The performance of complementary feeders, running in parallel, can be significantly improved by installing static transfer switches （STSs） at critical locations. We develop the STS control logic, which transfers the critical load from the preferred feeder to the alternate feeder when a voltage sag or a fault occurs on the preferred feeder. A forced commutation technique is proposed and implemented to turn off the preferred feeders＇ thyristor, thus avoiding cross current to flow and minimizing the transfer time. Simulation results show that the forced commutation technique is more effective as compared to the recently proposed time delay technique for STS operation. Two different feeders, namely New Exchange, the preferred feeder, and Sector 1-10/2, the alternate feeder of Islamabad Electric Supply COmpany （IESCO）, Pakistan, have been selected for case studies. The software PSCAD/EMTDC professional package has been used for simulation.

关键词： Complementary feeder Cross current Static transfer switch (STS) Sensitive load Voltage sag PSCAD/EMTDC

Stress distribution from railway track over geogrid reinforced ballast underlain by clay

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Earthquake Engineering and Engineering Vibration 2019年第1期18卷 77-93页

作者： Mohammed Y.Fattah mahmood R.mahmood Mohammed F.Aswad Civil Engineering Department University of TechnologyBaghdad Iraq Civil Engineering Department University of TechnologyBaghdad IraqAssistant

Railway ballast forms a major component of a conventional rail track and is used to distribute the load to the subgrade, providing a smooth running surface for trains. It plays a significant role in providing support for the rail track base and distributing the load to the weaker layer underneath. Ballast also helps with drainage, which is an important factor for any type of transportation structure, including railroads. Over time, ballast progressively deforms and degrades under dynamic loading and loses its strength. In this study, extensive laboratory tests were conducted to investigate the effect of load amplitude, geogrid position, and number of geogrid layers, thickness of ballast layer and clay stiffness on the behavior of the reinforced ballast layer and induced strains in a geogrid. A half full-scale railway was constructed for carrying out the tests, which consisted of two rails 800 mm in length with three wooden sleepers(900 mm × 10 mm × 10 mm). Three ballast thicknesses of 200, 300 and 400 mm were used in the tests. The ballast was overlying 500 mm thickness clay in two states, soft and stiff. The tests were carried out with and without geogrid reinforcement; the tests were performed in a well-tied steel box of 1.5 m length ×1 m width ×1 m height. Laboratory tests were conducted to investigate the response of the ballast and the clay layers where the ballast was reinforced by a geogrid. Settlement in ballast and clay, soil pressure and pore water pressure induced in the clay were measured in reinforced and unreinforced ballast cases. It was concluded that the amount of settlement increased as the simulated train load amplitude increased, and there was a sharp increase in settlement up to cycle 500. After that, there was a gradual increase that leveled out between, 2500 to 4500 cycles depending on the frequency used. There was a slight increase in the induced settlement when the load amplitude increased from 0.5 to 1 ton but it was higher when the load am

关键词： ballast geogrid reinforcement clay stress pore water pressure dynamic load

Electronic and thermoelectric properties of alkali metal-based perovskites CsYbF3 and RbYbF3

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Chinese Physics B 2020年第11期29卷 473-478页

作者： Q mahmood N A Noor T Ghrib Nessrin A Kattan Asif mahmood Shahid M Ramay Basic and Applied Scientific Research Center Imam Abdulrahman Bin Faisal UniversityP.O.Box 198231441DammamSaudi Arabia Department of Physics College of ScienceImam Abdulrahman Bin Faisal UniversityP.O.Box 198231441DammamSaudi Arabia Department of Physics Riphah International UniversityLahorePakistan Department of Physics Faculty of ScienceTaibah UniversityMedinaSaudi Arabia Chemical Engineering Department College of EngineeringKing Saud UniversityRiyadhSaudi Arabia Physics and Astronomy Department College of ScienceKing Saud University RiyadhRiyadhSaudi Arabia

The electronic and thermoelectric properties of alkali metal-based fluorides CsYbF3 and RbYbF3 are studied by using Wien2k and BoltzTraP *** structural and thermodynamic stability of these materials are confirmed by tolerance factor(0.94 and 0.99 for RbYbF3 and CsYbF3)and negative formation *** optimized lattice constants and bulk moduli are consistent with the results reported in the *** reported band gap for RbYbF3 is 0.86 eV which decreases to 0.83 eV by the replacement of Cs with *** electrical and thermal conductivities along with Seebeck coefficients decrease with temperature rising from 0 K to 800 *** large values of thermoelectric parameters for positive chemical potentials show that the character is dominated by *** studied materials have figures of merit 0.82 and 0.81 at room temperature respectively,for RbYbF3 and CsYbF3 and increase with temperature ***,the materials under study may have potential application values in thermoelectric generators and refrigerators.

关键词： density functional theory thermodynamic stability electrical conductivity figure of merit

Insight into generation of induced mesenchymal stem cells from induced pluripotent cells

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World Journal of Stem Cells 2022年第1期14卷 142-145页

作者： mahmood S Choudhery Ruhma mahmood Department of Biomedical Sciences King Edward Medical UniversityLahore 54000PunjabPakistan Department of Genetics and Molecular Biology University of Health SciencesLahore 54600PunjabPakistan Stem Cells Laboratory Allama Iqbal Medical CollegeLahore 54000PunjabPakistan

Mesenchymal stem cells(MSCs)have the potential for use in cell-based regenerative ***,hundreds of clinical trials are using MSCs for the treatment of various ***,MSCs are low in number in adult tissues;they show heterogeneity depending upon the cell source and exhibit limited proliferative potential and early senescence in in vitro *** factors negatively impact the regenerative potential of MSCs and therefore restrict their use for clinical *** a result,novel methods to generate induced MSCs(iMSCs)from induced pluripotent stem cells have been *** development and optimization of protocols for generation of iMSCs from induced pluripotent stem cells is necessary to evaluate their regenerative potential in vivo and in *** addition,it is important to compare iMSCs with primary MSCs(isolated from adult tissues)in terms of their safety and *** investigation of the properties of iMSCs in vitro and their long term behavior in animals is important for their translation from bench to bedside.

关键词： Induced mesenchymal stem cells Induced pluripotent stem cells Regenerative potential Pluripotent Multipotent Clinical studies

Dynamic replication of web contents

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Science in China(Series F) 2007年第6期50卷 811-830页

作者： Amjad mahmood Department of Computer Science University of Bahrain Kingdom of Bahrain

The phenomenal growth of the World Wide Web has brought huge increase in the traffic to the popular web sites. Long delays and denial of service experienced by the end-users, especially during the peak hours, continues to be the common problem while accessing popular sites. Replicating some of the objects at multiple sites in a distributed web-server environment is one of the possible solutions to improve the response time/latency. The decision of what and where to replicate requires solving a constraint optimization problem, which is NP-complete in gen- eral. In this paper, we consider the problem of placing copies of objects in a dis- tributed web server system to minimize the cost of serving read and write requests when the web servers have limited storage capacity. We formulate the problem as a 0-1 optimization problem and present a polynomial time greedy algorithm with backtracking to dynamically replicate objects at the appropriate sites to minimize a cost function. To reduce the solution search space, we present necessary condi- tions for a site to have a replica of an object in order to minimize the cost function. We present simulation results for a variety of problems to illustrate the accuracy and efficiency of the proposed algorithms and compare them with those of some well-known algorithms. The simulation results demonstrate the superiority of the proposed algorithms.

关键词： object replication Web distributed web-server system data placement Internet

A Soil Moisture Data Assimilation System for Pakistan Using PODEn4DVar and CLM4.5

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Journal of Meteorological Research 2019年第6期33卷 1182-1193页

作者： Tariq mahmood Zhenghui XIE Binghao JIA Ammara HABIB Rashid mahmood State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics(LASG) Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China University of Chinese Academy of Sciences Beijing 100049China Pakistan Meteorological Department Islamabad 44000Pakistan Key Laboratory of Water Cycle and Related Land Surface Processes Institute of Geographic Science and Natural Resources ResearchChinese Academy of SciencesBeijing 100101China

Soil moisture is an important state variable for land–atmosphere *** is a vital land surface variable for research on hydrology,agriculture,climate,and drought *** current study,a soil moisture data assimilation framework has been developed by using the Community Land Model version 4.5(CLM4.5)and the proper orthogonal decomposition(POD)-based ensemble four-dimensional variational assimilation(PODEn4 DVar)*** experiments were conducted at four agricultural sites in Pakistan by assimilating in-situ soil moisture *** results showed that it was a reliable *** quantify further the feasibility of the data assimilation(DA)system,soil moisture observations from the top four soil-depths(0–5,5–10,10–20,and 20–30 cm)were *** evaluation results indicated that the DA system improved soil moisture *** addition,updating the soil moisture in the upper soil layers of CLM4.5 could improve soil moisture estimation in deeper soil layers[layer 7(L7,62.0 cm)and layer 8(L8,103.8 cm)].To further evaluate the DA system,observing system simulation experiments(OSSEs)were designed for Pakistan by assimilating daily *** idealized experiments produced statistical results that had higher correlation coefficients,reduced root mean square errors,and lower biases for assimilation,which showed that the DA system is able to produce and improve soil moisture estimation in Pakistan.

关键词： PODEn4DVar Community Land Model version 4.5 data assimilation soil moisture Pakistan

Study of magnetic and optical properties of Zn1-xTMxTe(TM = Mn,Fe,Co,Ni) diluted magnetic semiconductors：First principle approach

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Chinese Physics B 2017年第2期26卷 452-460页

作者： Q mahmood M Hassan M A Faridi Department of Physics University of the Punjab Quaid-e-Azam Campus-54590 Lahore Pakistan Centre for High Energy Physics University of the Punjab Lahore Pakistan

We present structural,magnetic and optical characteristics of Zn_（1-x）TM_xTe（TM = Mn,Fe,Co,Ni and x = 6.25%）,calculated through Wien2 k code,by using full potential linearized augmented plane wave（FP-LAPW） *** optimization of the crystal structures have been done to compare the ferromagnetic（FM） and antiferromagnetic（AFM） ground state energies,to elucidate the ferromagnetic phase stability,which further has been verified through the formation and cohesive ***,the estimated Curie temperatures T_c have demonstrated above room temperature ferromagnetism（RTFM） in Zn_（1-x）TM_xTe（TM =Mn,Fe,Co,Ni and x= 6.25%）.The calculated electronic properties have depicted that Mn- and Co-doped ZnTe behave as ferromagnetic semiconductors,while half-metallic ferromagnetic behaviors are observed in Fe- and Ni-doped *** presence of ferromagnetism is also demonstrated to be due to both the p-d and s-d hybridizations between the host lattice cations and TM *** calculated band gaps and static real dielectric constants have been observed to vary according to Penn＇s *** evaluated band gaps lie in near visible and ultraviolet regions,which make these materials suitable for various important device applications in optoelectronic and spintronic.

关键词： magnetic semiconductors density functional theory optical and dielectric properties electron density of states and band structure of crystalline solids

Effect of Trimetazidine on Functional Capacity in Patient with Ischaemic Cardiomyopathy (TOFCAPI)

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International Journal of Clinical Medicine 2024年第2期15卷 55-67页

作者： Mohsin Ahmed Golam Morshed mahmood Hasan Khan Md. Arifur Rahman Muhammed Aminur Razzaque Shariful Islam Sayeedur Rahman Khan Chowdhury Md. Kudrat-E-Khuda Salahuddin Anis Shiblee Md. Habibur Rahman Department of Cardiology National Institute of Cardiovascular Diseases Dhaka Bangladesh Department of Cardiology Government Employee’s Hospital Dhaka Bangladesh Department of Cardiology Delta Hospital Ltd. Dhaka Bangladesh IPDI Foundation Dhaka Bangladesh

Objective: This study aimed to evaluate the efficacy of trimetazidine on exercise capacity via a six-minute walk test in patients with ischaemic cardiomyopathy and also evaluate the effect of trimetazidine on left ventricular function via echocardiography in the same population. Methods: This prospective observational study, conducted at the National Institute of Cardiovascular Diseases in Dhaka, Bangladesh, enrolled 200 patients with ischaemic cardiomyopathy and a depressed left ventricular ejection fraction (LVEF Results: In this study (n = 200) of ischaemic cardiomyopathy patients, the mean age was 58 years, with 76% of the patients being male. All study subjects received GDMT (Guideline-Directed Medical Therapy) for angina and heart failure. Those who received the modified released form of trimetazidine developed lesions during the 1st and 2nd follow-ups, during which the LVEF, LVIDd, and six-minute walk distance significantly improved (p Conclusion: The findings of the present study demonstrated that the addition of modified-release trimetazidine to GDMT can improve exercise capacity and left ventricular function in patients with ischaemic cardiomyopathy.

关键词： Bangladesh Heart Failure Exercise Capacity Trimetazidine Ischaemic Cardiomyopathy

Assessing effectiveness of nature-based solution with big earth data:60 years mangrove plantation program in Bangladesh coast

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Ecological Processes 2023年第1期12卷 165-192页

作者： Riffat mahmood Li Zhang Guoqing Li Key Laboratory of Digital Earth Science Aerospace Information Research InstituteChinese Academy of SciencesBeijing 100094China College of Resources and Environmental Studies University of Chinese Academy of SciencesBeijing 100094China Department of Geography and Environment Faculty of Life and Earth SciencesJagannath UniversityDhaka 1100Bangladesh International Research Center of Big Data for Sustainable Development Goals Beijing 100094China

Background In the climate change context,nature-based solution(NBS)is considered one of the effective tools to increase the resilience of socio-ecological *** concept coincides with the government’s attempts of afforestation and reforestation programs that have been going on for 60 years in *** study,therefore,envisaged understanding how NBS(mangrove afforestation and reforestation)works to promote climate change resilience through the synthetization of remote sensing-based big earth data,statistical tools,and *** study took the entire coast of Bangladesh except for Sundarbans Reserve Forest and rolled back to 1962 to work on 60 years’time series *** CORONA satellite imagery along with Landsat satellite imagery was used,which is the first-ever attempt in the remote sensing-based ecosystem work in *** The study’s main innovation is to spatially establish the effectiveness of the *** study critically assessed and estimated stable lands and their socio-economic benefits as part of the effectiveness of the *** part of the NBS-derived benefits in the context of climate change,it estimated the sequestrated carbon in mangrove forests.A significant positive relationship was observed between the increase of mangroves and stable *** about 448,011 ha of agricultural land was stabilized due to the NBS intervention whose economic value is 18,837 million *** addition,29,755.71 kt of carbon have been sequestrated due to NBS *** The concept of NBS is still in the development stage and very little or no work has been done so far in measuring and labeling the effectiveness of the ***,our study can innovatively contribute to the scientific community to show the effectiveness of the NBS in three domains(social,economic and ecological)in the changing climatic scenario.

关键词： Nature-based solution(NBS) Mangrove afforestation program Coast Geographic Information System Remote sensing CORONA satellite image Land stabilization Sequestrated carbon Climate change

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