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Effect of elevated temperature and silica sand particle size on minimum fluidization velocity in an atmospheric bubbling fluidized bed

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Chinese Journal of Chemical Engineering 2020年第12期28卷 2985-2992页

作者： A.Al-Farraji haidar Taofeeq Chemical Engineering Department College of EngineeringAl-Nahrain UniversityBaghdadIraq Prosthetics and Orthotics Engineering Department College of EngineeringAl-Nahrain UniversityBaghdadIraq

The impact of temperature and particle size on minimumfluidizing velocity was studied and analyzed in a small pilot scale of bubbling fluidized bed *** study was devoted to providing some data about fluidization to the literature under high temperature *** experiments were carried out to evaluate the minimum fluidizing velocity over a vast range of temperature levels from 20℃ to 850℃ using silica sand with a particle size of 300-425μm,425-500μm,500-600μm,and 600-710μ***,the variation in the minimumfluidized voidage was determined experimentally at the same *** experimental data revealed that the Umf directly varied with particle size and inversely with temperature,whileεmf increases slightly with temperature based on the measurements of height at incipient ***,for all particle sizes used in this test,temperatures above 700℃ has a marginal effect on *** results were compared with many empirical equations,and it was found that the experimental result is still in an acceptable range of empirical equations *** which,our findings are not well predicted by the widely accepted correlations reported in the ***,a new predicted equation has been developed that also accounts for the affecting of mean particle size in addition to other parameters.A good mean relative deviation of 5.473% between the experimental data and the predicted values was estimated from the correlation of the effective dimensionless ***,the experimental work revealed that the minimum fluidizing velocity was not affected by the height of the bed even at high temperature.

关键词： Minimum fluidization velocity Voidage Elevated temperature Silica sand Fluidized bed Bed height

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TS Fuzzy Prediction-based SVC Compensation of Wind Farms Flicker:A Dual-UKF Approach

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CSEE Journal of Power and Energy Systems 2022年第6期8卷 1594-1602页

作者： Saeedeh Ketabipour haidar Samet Navid Vafamand School of Electrical and Computer Engineering Shiraz UniversityShirazIran Department of Electrical Engineering Eindhoven University of TechnologyEindhoventhe Netherlands

Fast fluctuations in wind farm power produce voltage flicker in the *** way to mitigate the flicker is to place a static VAr compensator(SVC).Due to the operating delay of SVCs,it is essential to predict the wind farm reactive ***,a novel fuzzy nonlinear modeling approach is suggested and used in the one-step-ahead prediction of the power *** base of the developed fuzzy modeling is the Takagi-Sugeno fuzzy representation and a dual-unscented Kalman filter(D-UKF).In other words,a nonlinear TS fuzzy system is trained online via the *** forecasted value is used as the SVC’s reference signal.A large amount of actual data gathered from a wind farm is used for the performance *** data is collected in winter and summer for different climate *** the actual data,a current source with changing amplitude and phase which is updated every half-cycle,is used to model the wind *** results,including the flicker indices,confirm the improvement in the SVC’s performance.

关键词： SVC voltage flicker wind farm

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Comparison between the new mechanistic and the chaos scale-up methods for gas-solid fluidized beds

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Chinese Journal of Chemical Engineering 2018年第6期26卷 1401-1411页

作者： haidar Taofeeq Muthanna AI-Dahhan Multiphase Reactors Engineering and Applications Laboratory (mReal) Department of Chemical & Biochemical Engineering Missouri University of Science & Technolog y Rolla MO 65409 USA Chemical Engineering Department College of Engineering AI-Nahrain University Baghdad Iraq Cihan University. Erbil Iraq Prosthetics and Orthotics Engineering Department College of Engineering AI-Nahrain University Baghdad Iraq

The chaotic scale-up approach by matching the Kolmogorov entropy(E_K) proposed by Schouten et al.(1996) was assessed in two geometrically similar gas–solid fluidized bed columns of 0.14 and 0.44 m *** used four conditions of our validated new mechanistic scale-up method based on matching the radial profiles of gas holdup where the local dimensionless hydrodynamic parameters were similar as measured by advanced measurement *** experimental conditions were used to evaluate the validity of the chaotic scale-up method,which were selected based on our new mechanistic scale-up *** gauge transducer measurements at the wall and inside the bed at various local radial locations and at three axial heights were used to estimate *** was found that the experimental conditions with similar or close radial profiles of the Kolmogorov entropy and with similar or close radial profiles of the gas holdup achieve the similarity in local dimensionless hydrodynamic parameters,and vice versa.

关键词： Scale-up Chaotic analysis approach New scale-up methodology Kolmogorov entropy Gas–solid fluidized bed

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Hierarchical assemblies of molecular frameworks—MOF-on-MOF epitaxial heterostructures

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Nano Research 2021年第2期14卷 355-368页

作者： Ritesh haidar Christof Woll Institute of Functional Interfaces(IFG) Karlsruhe Institute of Technology(KIT)Hermann-von-Helmholtz-Platz176344 Eggenstein-LeopoldshafenGermany

Functional,porous metal-organic frameworks(MOFs)have attracted much attention as a very flexible class of crystalline,porous *** more advanced applications that exploit photophysical properties,the fabrication of hierarchical assemblies,including the creation of MOF/MOF heterointerfaces,is *** the manufacturing of superstructures with length scales well beyond that of the MOF pore size,layer-by-layer(Ibl)methods are particularly *** allow the isoreticular approach to be extended to superstructures with micrometer length scales,a range that is not accessible using conventional MOF *** Ibl approach further substantially extends the compositional diversity in *** the same time,the favorable elastic properties of MOFs allow for heteroepitaxial growth,even in the case of lattice misfits as large as 20%.While the MOF-on-MOF approach to designing multicomponent superstructures with synergistic multifunctionality can also be realized with sophisticated solvothermal synthesis schemes,the Ibl(or liquid-phase epitaxy)approach carries substantial advantages,in particular when it comes to the integration of such MOF superstructures into optical or electronic *** the structure vertical to the substrate can be adjusted using the Ibl method,photolithographic methods can be used for lateral *** this review,we will discuss the Ibl liquid-phase epitaxy approach to growing surface-anchored MOF thins films(SURMOFs)as well as other relevant one-pot synthesis methods for constructing such hierarchically designed structures and their emerging applications.

关键词： metal-organic framework(MOF)heterostaicture hierarchical assembly epitaxy layer-by-layer growth surface-anchored MOFs

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Effective Controlled Islanding Method for Power Grids Solving a Sequence of Optimization Problems

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CSEE Journal of Power and Energy Systems 2022年第4期8卷 1004-1012页

作者： Mahdi Amini haidar Samet Ali Reza Seifi Mahdi Davarpanah School of Electrical and Computer Engineering Shiraz UniversityShirazIran Department of Electrical Engineering Eindhoven University of TechnologyEindhoventhe Netherlands the Electrical and Computer Engineering School College of EngineeringUniversity of TehranTehranIran

Controlled islanding is an important approach to prevent instability in power *** this paper,a novel approach is proposed for power system separation,which consists of two steps:1)Finding multiple islanding scenarios;2)Choosing the best option to obtain the most desirable *** the first step,different islanding solutions are determined by a proposed hierarchical clustering *** this algorithm,which is based on a minimum active power flow disruption objective function,the generator coherency constraints are considered in the clustering *** the second step,the best separation scenario is chosen based on an arbitrary objective ***,in this paper,the amount of load shedding and the voltage profile deviation after separation are considered as the final criteria to select the best solution among available *** so doing,the degree of load importance is also taken into *** proposed two-step method is applied on an IEEE 9-bus test system and it is also evaluated on an IEEE 39-bus *** simulation results on the IEEE 39-bus grid and the comparative analysis with a state-of-the-art method confirm that the final islanding solution is more optimized based on the secondary criteria,which have not been addressed in the existing ***,the proposed method is computationally efficient and can be employed in real-scale power grids.

关键词： Graph theory hierarchical spectral clustering power system separation power system instability two-step approach.

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Factors influencing adherence to the food by prescription program among adult HIV positive patients in Addis Ababa, Ethiopia: a facility-based, cross-sectional study

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Infectious diseases of Poverty 2014年第1期3卷 182-191页

作者： Mesrach Ayalew Kebede Jemal haidar St.Paul’s Hospital Millennium Medical College Addis AbabaEthiopia School of Public Health Addis Ababa UniversityP.O.Box 27285/1000Addis AbabaEthiopia

Background:One way of addressing malnutrition among HIV/AIDS patients is through the Food by Prescription program(FBP)and many studies have explained the treatment outcomes after therapeutic food supplementation,though available evidences on adherence levels and factors associated with these sorts of programs are *** findings of this study would therefore contribute to the existing knowledge on adherence to Ready-to-Use Therapeutic/Supplementary Food(RUF)in ***:A facility-based,cross-sectional study supplemented with qualitative methods was conducted among 630 adult HIV+*** level of adherence to RUF was measured using the Morisky 8-item Medication Adherence Scale(MMAS-8).The total score on the MMAS-8 ranges from 0 to 8,with scores ofdium,and high adherence,*** who had a low or a moderate rate of adherence were considered ***:The level of adherence was found to be 36.3%with a 95.0%response *** the exception of the educational status,other socio-demographic variables had no significant effect on *** who knew the benefits of the FBP program were 1.78 times more likely to adhere to the therapy than the referent *** the other hand,patients who were not informed on the duration of the treatment,those prescribed with more than 2 sachets/day and had been taking RUF for more than 4 month were less likely to *** main reasons for non-adherence were not liking the way the food tasted and missing follow-up *** and sharing and selling food were the other reasons,as deduced from the focus group discussion(FGD)***:The observed level of adherence to the FBP program among respondents enrolled in the intervention program was *** major factors identified with a low adherence were a low level of education,poor knowledge on the benefits of RUF,the longer duration of the program,consuming more than two prescribed sachets of

关键词： Factors Adherence Food by prescription program HIV positive Addis Ababa Ethiopia

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Evaluation of climate change effects on extreme flows in a catchment of western Iran

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Frontiers of Earth Science 2019年第3期13卷 523-534页

作者： Soheila SAFARYAN Mohsen TAVAKOLI Noredin ROSTAMI haidar EBRAHEVH Department of Natural Resources Ilam UniversityDam 69315516Iran Department of Watershed Management Faculty of Natural Resources and Earth SciencesUniversity of KashanKashan ***Iran

Investigation of the relationship between catchment hydrology with climate is essential for understanding of the impact of future climate on hydrological extremes, which may cause frequent flooding, drought, and shortage of water supply. The purpose of this study is to investigate the effects of climate change on extreme flows in one of the subcatchments of the Ilam dam catchment, Iran. The changes in climate parameters were predicted using the outputs of HadCM3 model for up to the end of the current century in three time periods including 2020s, 2050s, and 2080s. For A2 scenario, increases of 1.09℃, 2.03℃, and 3.62℃, and for B2 scenario rises of 1.18℃, 1.84℃, and 2.55℃ have been predicted. The results suggest that for A2 scenario, the amount of precipitation would decrease by 12.63, 49.13, and 63.42 and for B2 scenario by 47.02,48.51, and 70.26 mm per year. Also the values of PET for A2 scenario would increase by 51.18, 101.47 and 108.71 and for B2 scenario by 60.09, 89.86, and 124.32 mm per year. The results of running the SWAT model revealed that the average annual runoff would decrease by 0.11, 0.41, and 0.61 m3/s and for B2 scenario by 0.39, 0.47, and 0.59 m3/s. The extreme flows were then analyzed by running WETSPRO model. According to the results, the amounts of low flows for A2 scenario will decrease by 0.02, 0.21 and 0.33 m^3/s and for B2 scenario by 0.19, 0.26 and 0.29 m^3/s in the 2020s, 2050s and 2080s, respectively. On the other hand, the results show an increase of peak flows by 11.5, 19.1 and 48.7 m^3/s in A2 scenario and 11.12, 25.93 and 48.1 m^3/s in B2 scenario, respectively. Overall, the results indicated that an increase in return period leads to elevated levels of high flows and diminished low flows.

关键词： climate change extreme flows Ilam dam watershed Iran

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On the Marchenko System and the Long-time Behavior of Multi-soliton Solutions of the One-dimensional Gross-Pitaevskii Equation

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Journal of Partial differential Equations 2015年第2期28卷 167-196页

作者： MOHAMAD haidar Departement de Mathematiques Universite Paris-Sud 11 F-91405 Orsay Cedex.

We establish a rigorous well-posedness results for the Marchenko system associated to the scattering theory of the one dimensional Gross-Pitaevskii equation （GP）. Under some assumptions on the scattering data, these well-posedness results provide regular solutions for （GP）. We also construct particular solutions, called N- soliton solutions as an approximate superposition of traveling waves. A study for the asymptotic behaviors of such solutions when t-→±∞ is also made.

关键词： Non-linear Schr6dinger equation Gross-Pitaevskii equation.

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Analysis of Convective Heat Exchanges and Fluid Dynamics in the Air Gap of a discoid Technology Rotary Machine

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Frontiers in Heat and Mass Transfer 2024年第3期22卷 733-746页

作者： Abdellatif El Hannaoui Rachid Boutarfa Chadia haidar Mechanical Engineering Industrial Management and Innovation LaboratoryFaculty of Science and TechniquesHassan 1st UniversitySettatMorocco Department of Energy Laboratory University Moulay IsmailENSAMMeknèsMorocco

The proposedwork focuses on the in-depth study of convective heat transfer in the unconfined air gap of a discoidal rotor-stator *** rotary cooling mechanism is achieved by the injection of two air jets,while the cavity geometry is characterized by a dimensionless parameter *** numerical analysis primarily concentrated on the effect of flow velocity and rotation on the heat exchange *** precisely,the range of analysis extends from the rotational Reynolds number Re_(ω)=2.35×10^(5)to Re_(ω)=5.04×10^(5),while varying the Reynolds value of the jet in a range from 16×10^(3)to 55.46×10^(3).To carry out this analysis,a numerical simulation was conducted with Ansys-Fluent software,using the RSM turbulence *** results of the study significantly reveal the impact of rotation on heat exchange transfer within the cavity,identifying two distinct zones of fluid *** zones exhibit remarkable heat transfer characteristics,contributing to a better understanding of the complexmechanisms governing heat transfer in this particular technological ***,the analysis of radial mean velocity distributions,as well as local and mean Nusselt numbers,provides further insight into the heat transfer performance of this unique configuration.

关键词： Heat transfer rotor-stator impacting jets RSM turbulence model

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Sparse Approximations of the Schur Complement for Parallel Algebraic Hybrid Solvers in 3D

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Numerical Mathematics(Theory,Methods and Applications) 2010年第3期3卷 276-294页

作者： L.Giraud A.haidar Y.Saad Joint INRIA-CERFACS Lab-42 AV.Coriolis 31057ToulouseFrance Department of Computer Science University of TennesseeKnoxvilleTN37996USA. Department of Computer Science and Engineering University of MinnesotaMinneapolisMN55455USA

In this paper we study the computational performance of variants of an algebraic additive Schwarz preconditioner for the Schur complement for the solution of large sparse linear *** earlier works,the local Schur complements were computed exactly using a sparse direct *** robustness of the preconditioner comes at the price of this memory and time intensive computation that is the main bottleneck of the approach for tackling huge *** this work we investigate the use of sparse approximation of the dense local Schur *** approximations are computed using a partial incomplete LU *** a numerical calculation is the core of the multi-level incomplete factorization such as the one implemented in pARMS. The numerical and computing performance of the new numerical scheme is illustrated on a set of large 3D convection-diffusion problems;preliminary experiments on linear systems arising from structural mechanics are also reported.

关键词： Hybrid direct/iterative solver domain decomposition incomplete/partial factorization Schur approximation scalable preconditioner convection-diffusion large 3D problems parallelscientific computing High Performance Computing.

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