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Clean Energy 2021年第4期5卷 673-689页

作者： hassan mahmood Khaled Hossin Mechanical and Construction Engineering University of NorthumbriaNewcastle upon TyneUK Mechanical and Industrial Engineering Department American University of Ras Al KhaimahRas Al KhaimahUnited Arab Emirates Mechanical Engineering Department University of BenghaziBenghaziLibya

The organic Rankine cycle(ORC)coupled with a linear Fresnel reflector(LFR)utilizes a low-grade heat *** article presents the study of a small-scale LFR-ORC power-generation plant under the climatic conditions of Almatret,*** mathematical modelling is performed using thermodynamic equations and simulations are conducted to evaluate the optical performance of the LFR system and thermal performance of the ORC ***-62 is used as a heat-transfer fluid(HTF)in the solar field,whereas NOVEC^(TM) 649 is used as the working fluid in the ORC power *** LFR is integrated with a thermal-storage unit based on a two-tank system and stores the solar thermal energy via a heat *** thermal-energy output of the receiver tube of the LFR system is 108 kW and thermal losses are 7.872 kW during the peak time operation of a day at 1:00 *** mechanical power output of the ORC turbine is 7.296 kW using the specific design conditions and the two-tank thermal-storage system adds 4 operation hours to the power plant after sunset.

关键词： solar energy linear Fresnel reflector energy storage organic Rankine cycle

Adaptive Dual Wavelet Threshold Denoising Function Combined with Allan Variance for Tuning FOG-SINS Filter

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Journal of Shanghai Jiaotong university(Science) 2020年第4期25卷 434-440页

作者： BESSAAD Nassim BAO Qilian SUN Shuodong DU Yuding LIU Lin hassan mahmood Ul School of Electronic Information and Electrical Engineering Shanghai Jiao Tong UniversityShanghai 200240China Shanghai Aerospace Control Technology Institute Shanghai 201109China

Allan variance(AV)stochastic process identification method for inertial sensors has successfully combined the wavelet transform denoising ***,the latter usually employs a traditional hard threshold or soft threshold that presents some mathematical *** adaptive dual threshold for discrete wavelet transform(DWT)denoising function overcomes the disadvantages of traditional *** that two thresholds for noise and signal and special fuzzy evaluation function for the signal with range between the two thresholds assure continuity and overcome previous *** the basis of AV,an application for strap-down inertial navigation system(SINS)stochastic model extraction assures more efficient tuning of the augmented 21-state improved exact modeling Kalman filter(IEMKF)*** experimental results show that the proposed algorithm is superior in denoising ***,the improved filter estimation of navigation solution is better than that of conventional Kalman filter(CKF).

关键词： Allan variance(AV) discrete wavelet transform(DWT) adaptive dual threshold fiber optic gyroscope(FOG) strap-down inertial navigation system(SINS) exact modeling filter

Adsorption and desorption of acetone by TiO_(2) clusters:Transition state theory and sensing analysis

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ChemPhysMater 2023年第4期2卷 351-355页

作者： Mudar Ahmed Abdulsattar Tasneem hassan mahmood Hussein Hakim Abed Hayder M.Abduljalil Department of Pharmacy Al-Rasheed University CollegeBaghdad 10011Iraq Ministry of Science and Technology Baghdad 10011Iraq Department of Physics College of Science for WomenUniversity of BaghdadBaghdad 10011Iraq Department of Physics College of ScienceUniversity of BabylonBabylon 51005Iraq

TiO_(2) cluster sensitivity to acetone adsorption using transition state theory is ***_(10)O_(20) cluster is used to perform the calculations using density functional theory with dispersion *** state and transition state are calculated via thermodynamic energies,i.e.,Gibbs free energy of adsorption and *** rate,response,response time,and recovery time as a function of temperature and acetone concentration are *** burning in the air due to autoignition is considered using a logistic *** results of the theory are compared with available experimental findings that revealed the quality of both theoretical and experimental *** response time decreases with respect to acetone *** the other hand,the recovery time in the desorption phase increases with acetone *** temperature of maximum response is 356℃,while the maximum response value is 2.9.

关键词： TiO_(2) Acetone Transition state Sensor Density functional theory

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

Structural characterization of AA 2024-MoSi_2 nanocomposite powders produced by mechanical milling

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International Journal of Minerals,Metallurgy and Materials 2013年第3期20卷 298-306页

作者： mahmood Sameezadeh hassan Farhangi Massoud Emamy Center of Excellence for High Performance Materials School of Metallurgy and Materials College of Engineering University of Tehran

Nano-sized MoSi2 powder was produced successfully from commercially available MoSi2 by a mechanical milling process carried out for 100 h, and mechanical alloying was employed to synthesize AA 2024-MoSi2 nanocomposites, The effects of MoSi2 reinforcement and mechanical milling on the structure, morphology, and iron contamination of the produced materials were investigated using X-ray diffraction, scanning electron microscopy, and atomic absorption spectrometry. It is revealed that the morphology of the aluminum alloy changes continuously during milling from spherical to plate-like, irregular, and finally equiaxed. The presence of MoSi2 reinforcement accelerates the milling process and results in a smaller average particle size. The Williamson-Hall method determined that the crystallite size of the aluminum alloy in the composite powder is smaller than that of the unreinforced alloy at the same milling time and this size reaches 45 nm after 16 h milling time. The Fe contamination content is higher for the nanocomposite in comparison with the unreinforced alloy because of the wearing role of MoSi2 hard particles.

关键词： nanocomposites aluminum alloys mechanical milling microstructure

Theoretical investigation of optical properties and band gap engineering for Zn1-xTMxTe(TM=Fe,Co)alloys by modified Becke-Johnson potential

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Chinese Physics B 2017年第8期26卷 491-498页

作者： Q mahmood M Yaseen M hassan Shahid M Ramay Asif mahmood Materials Growth and Simulation Laboratory Department of PhysicsUniversity of the PunjabQuaid-i-Azam Campus54590LahorePakistan Department Of Physlcs University of Agriculture UniversityFaisalabad 38040Pakistan Physics and Astronomy Department College of ScienceKing Sand UniversityRiyadhSaudi Arabia Chemical Engineering Department College of EngineeringKing Saud UniversityRiyadhSaudi Arabia

The direct band gap ZnTe with transition metal （TM） impurities plays a vital role in optoelectronic and spintronic applications. In the present study, we use the advanced modified Becke-Johnson （mBJ） functional for performing the structural computations and detailed investigations of the optical characters in Zn1_xTMxTe （TM = Fe, Co） alloys with 0 ≤ x ≤1. By employing the FP-LAPW method, we determine various optical parameters for the ternary alloys and for the end binaries. The calculated static dielectric constants and optical band gaps for Zn1_xTMxTe （TM = Fe, Co） have an inverse relation that verifies the Penn model. We find that the static dielectric constant is nearly equal to the square of the static refractive index, and both increase with TM content. Furthermore, we also find a slight shift of peaks to a higher energy region with increasing TM concentration. The decreasing band gap and high value of the absorption in the visible region of electromagnetic spectrum make these alloys suitable for photonic and solar cell applications.

关键词： amorphous semiconductors transition metal-doped ZnTe structural computation optical property

An exact analytical solution for convective heat transfer in rectangular ducts

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2012年第10期13卷 768-781页

作者： Mohammad Mohsen SHAHMARDAN mahmood NOROUZI Mohammad hassan KAYHANI Amin AMIRI DELOUEI Department of Mechanical Engineering Shahrood University of TechnologyShahroodIran

An exact analytical solution is obtained for convective heat transfer in straight ducts with rectangular cross-sections for the first *** solution is valid for both H1 and H2 boundary conditions,which are related to fully developed convective heat transfer under constant heat flux at the duct *** separation of variables method and various other mathematical techniques are used to find the closed form of the temperature *** local and mean Nusselt numbers are also obtained as functions of the aspect ratio.A new physical constraint is presented to solve the Neumann problem in non-dimensional analysis for the H2 boundary *** is one of the major innovations of the current *** analytical results indicate a singularity occurs at a critical aspect ratio of 2.4912 when calculating the local and mean Nusselt numbers.

关键词： Exact analytical solution Convective heat transfer Straight duct Rectangular cross-section Constant heat flux

Predisposing factors, clinical assessment, management and outcomes of agitation in the trauma intensive care unit

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World Journal of Emergency Medicine 2018年第2期9卷 105-112页

作者： Saeed mahmood Omaima mahmood Ayman El-Menyar Mohammad Asim hassan Al-Thani Trauma Surgery Section Department of Surgery Hamad General Hospital (HGH) Doha Qatar College of Pharmacy Qatar University Doha Qatar Clinical Research Trauma Surgery Section Department of Surgery HGH Doha Qatar Clinical Medicine Weill Cornell Medical School Doha Qatar

BACKGROUND: Agitation occurs frequently among critically ill patients admitted to the intensive care unit(ICU). We aimed to evaluate the frequency, predisposing factors and outcomes of agitation in trauma ICU. METHODS: A retrospective analysis was conducted to include patients who were admitted to the trauma ICU between April 2014 and March 2015. Data included patient's demographics, initial vitals, associated injuries, Ramsey Sedation Scale, Glasgow Coma Scale, head injury lesions, use of sedatives and analgesics, head interventions, ventilator days, and ICU length of stay. Patients were divided into two groups based on the agitation ***: A total of 102 intubated patients were enrolled; of which 46(45%) experienced agitation. Patients in the agitation group were 7 years younger, had significantly lower GCS and sustained higher frequency of head injuries(P<0.05). Patients who developed agitation were more likely to be prescribed propofol alone or in combination with midazolam and to have frequent ICP catheter insertion, longer ventilatory days and higher incidence of pneumonia(P<0.05). On multivariate analysis, use of propofol alone(OR=4.97; 95% CI=1.35–18.27), subarachnoid hemorrhage(OR=5.11; 95% CI=1.38–18.91) and ICP catheter insertion for severe head injury(OR=4.23; 95% CI=1.16–15.35) were independent predictors for agitation(P<0.01).CONCLUSION: Agitation is a frequent problem in trauma ICU and is mainly related to the type of sedation and poor outcomes in terms of prolonged mechanical ventilation and development of nosocomial pneumonia. Therefore, understanding the main predictors of agitation facilitates early risk-stratification and development of better therapeutic strategies in trauma patients.

关键词： Trauma Intensive care unit Agitation Head injury Propofol Outcome

Investigating biological population model using exp-function method

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International Journal of Biomathematics 2016年第2期9卷 159-173页

作者： Qazi mahmood Ul hassan Syed Tauseef Mohyud-Din Department of Mathematics Faculty of Sciences HITEC University Taxila 47080 Pakistan

This paper is the spectator of the arrangement of an efficient transformation and exfunction technique to build up generalized exact solutions of the biological population model equation. Computational work and subsequent numerical results re-identify the effectiveness of proposed algorithm. It is pragmatic that recommended plan is greatly consistent and may be comprehensive to other nonlinear differential equations of fractional order.

关键词： Biological population model fractional calculus exp-function method.

Analyzing drying characteristics and modeling of thin layers of peppermint leaves under hot-air and infrared treatments

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Information Processing in Agriculture 2017年第2期4卷 128-139页

作者： Seyed-hassan Miraei Ashtiani Alireza Salarikia mahmood Reza Golzarian Department of Biosystems Engineering Faculty of AgricultureFerdowsi University of MashhadMashhadIran

The drying kinetics of peppermint leaves was studied to determine the best drying method for *** drying methods include hot-air and infrared techniques,were *** different temperatures(30,40,50℃)and air velocities(0.5,1,1.5 m/s)were selected for the hot-air drying *** levels of infrared intensity(1500,3000,4500 W/m^2),emitter-sample distance(10,15,20 cm)and air speed(0.5,1,1.5 m/s)were used for the infrared drying *** to the results,drying had a falling rate over *** kinetics of peppermint leaves was explained and compared using three mathematical *** determine coefficients of these models,non-linear regression analysis was *** models were evaluated in terms of reduced chi-square(χ^2),root mean square error(RMSE)and coefficient of determination(R^2)values of experimental and predicted moisture *** analyses indicated that the model with the best fitness in explaining the drying behavior of peppermint samples was the Logarithmic model for hot-air drying and Midilli model for infrared *** transfer in peppermint leaves was also described using Fick’s diffusion *** lowest effective moisture diffusivity(1.096×10^-11m^2/s)occurred during hot-air drying at 30℃ using 0.5 m/s,whereas its highest value(5.928×10^-11m^2/s)belonged to infrared drying using 4500 W/m^2 infrared intensity,0.5 m/s airflow velocity and 10 cm emitter-sample *** activation energy for infrared and hot-air drying were ranged from 0.206 to 0.439 W/g,and from 21.476 to 27.784 kJ/mol,respectively.

关键词： Drying kinetics Effective diffusivity Energy activation Moisture ratio Moisture removal Semi-theoretical model