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Journal of Hydrodynamics 2014年第2期26卷 277-290页

作者： TRIVEDI Chirag CERVANTES Michel J. GANDHI B.K. OLE DAHLHAUG G. Division of Fluid and Experimental Mechanics Department of Engineering Sciences and Mathematics Lule? University of Technology Department of Mechanical and Industrial Engineering Indian Institute of Technology Water Power Laboratory Department of Energy and Process Engineering Norwegian University of Science and Technology

Penetration of the power generated using wind and solar energy to electrical grid network causing several incidents of the grid tripping, power outage, and frequency drooping. This has increased restart （star-stop） cycles of the hydroelectric turbines significantly since grid connected hydroelectric turbines are widely used to manage critical conditions of the grid. Each cycle induces significant stresses due to unsteady pressure loading on the runner blades. The presented work investigates the pressure loading to a high head （ He = 377 m, De = 1.78 m） Francis turbine during start-stop. The measurements were carried out on a scaled model turbine （HM = 12.5 m, DM = 0.349 m）. Total four operating points were considered. At each operating point, three schemes of guide vanes opening and three schemes of guide vanes closing were investigated. The results show that total head variation is up to 9% during start-stop of the turbine. On the runner blade, the maximum pressure amplitudes are about 14 kPa and 16 kPa from the instantaneous mean value of 121 kPa during rapid start-up and shutdown, respectively, which are about 1.5 times larger than that of the slow start-up and shutdown. Moreover, the maximum pressure fluctuations are given at the blade trailing edge.

关键词： Francis turbine pressure fluctuations start-up shutdown transient

Validity of Existing Rain Water Harvesting Dams within Part of Western Desert, Iraq

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Engineering（科研） 2019年第12期11卷 806-818页

作者： Khaldoon Khaled Alwan Manal Shakir Ali Al-Kubaisi Nadhir Al-Ansari Department of Geology College of Science University of Baghdad Iraq Department of Civil Environmental and Natural Resources Luleå University of Technology Luleå Sweden

The study area is located within the western part of Iraq between Latitude (32°45'0'' - 34°0'0'') North and longitude (39°30'0'' - 40°45'0'') East within Anbar Governorate. It covers an area of 4767.423 Km2 with elevation ranges from 360 to 840 m. The general slope decreases from southwest to northeast. Five old dams identified in the study area. The results of SWAT model showed high curve number (70 - 85) indicating low filtration and runoff rate (1.2 - 8.2) mm for the period (1994-2014). These dams have catchment areas ranged between (118.03 - 673.41) km2. They were to be used for agricultural purposes. The results according to the Food, Agriculture Organization (FAO) standards for their distance from agricultural areas using a GIS showed that all are not suitable except dam number (1). The distance to roads showed that dams (1, 4) are highly suitable, (2, 3) are low suitable and dam (5) is not suitable. The average annual quantity of rain water that can be harvested from the 5 dams is about 12.9 million cubic meters.

关键词： Anbar Runoff Suitability SWAT Mode

Application of SimaPro7 on Al-Hilla City Sewerage Network, Iraq

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Engineering（科研） 2015年第5期7卷 224-229页

作者： Mohammad Ali Alanbari Hind Qasim Alazzawi Nadhir Al-Ansari Sven Knutsson College of Engineering Babylon University Babylon Iraq Department of Civil Environmental and Natural Resources Engineering Lule&aring University of Technology Lule&aring Sweden

SimaPro is a software package designed to make a valuable contribution for analyzing the environmental impact on products during their whole life cycle. A huge amount of knowledge about the environment is built into the program and database, enabling to analyze a product with a minimum of specialized knowledge. In this study, SimaPro was used to analyze and evaluate the impacts that resulted from sewerage network in Al-Hilla city, Iraq. The results of Life Cycle Assessment (LCA) showed that sewerage network had an impact and damage on the environment by 291 points for every cubic meter of collect wastewater. The most potential environmental impacts were global warming, respiratory inorganics and non-renewable energy, contributing to the sewerage network. The study also showed that most of the effects were as a result of energy consumption in the pumping of wastewater, pipes used and diesel using for network operation.

关键词： SimaPro Environmental Impact Life Cycle Assessment (LCA) Sewerage Network Al-Hilla Iraq

Structure inversion asymmetry enhanced electronic structure and electrical transport in 2D A3SnO(A=Ca,Sr,and Ba)antiperovskite monolayers

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Nano Research 2023年第1期16卷 1779-1791页

作者： Syed Muhammad Alay-e-Abbas Ghulam Abbas Waqas Zulfiqar Muhammad Sajjad Nirpendra Singh J.Andreas Larsson Applied Physics Division of Materials ScienceDepartment of Engineering Sciences and MathematicsLuleåUniversity of Technology97187 LuleåSweden Computational Materials Modeling Laboratory Department of PhysicsGovernment College UniversityFaisalabad 38040Pakistan Department of Energy Conversion and Storage Technical University of Denmark2800 Kgs.LyngbyDenmark Department of Physics Khalifa University of Science and TechnologyAbu Dhabi-127788United Arab Emirates Center for Catalysis and Separation(CeCaS) Khalifa University of Science and TechnologyAbu Dhabi-127788United Arab Emirates

Anti-perovskites A3SnO(A=Ca,Sr,and Ba)are an important class of materials due to the emergence of Dirac cones and tiny mass gaps in their band structures originating from an intricate interplay of crystal symmetry,spin–orbit coupling,and band *** provides an exciting playground for modulating their electronic properties in the two-dimensional(2D)***,we employ first-principles density functional theory(DFT)calculations by combining dispersion-corrected SCAN+rVV10 and mBJ functionals for a comprehensive side-by-side comparison of the structural,thermodynamic,dynamical,mechanical,electronic,and thermoelectric properties of bulk and monolayer(one unit cell thick)A3SnO *** results show that 2D monolayers derived from bulk A3SnO anti-perovskites are structurally and energetically ***,Rashba-type splitting in the electronic structure of Ca3SnO and Sr3SnO monolayers is observed owing to strong spin–orbit coupling and inversion *** the other hand,monolayer Ba3SnO exhibits Dirac cone at the high-symmetryΓpoint due to the domination of band *** on the predicted electronic transport properties,it is shown that inversion asymmetry plays an essential character such that the monolayers Ca3SnO and Sr3SnO outperform thermoelectric performance of their bulk counterparts.

关键词： electrical transport anti-perovskites low-dimensional materials electronic structure mechanical properties

Fabrication of MoSi;coatings on molybdenum and its high-temperature anti-oxidation properties

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Transactions of Nonferrous Metals Society of China 2022年第3期32卷 935-946页

作者： Lu ZHU Peng CHEN Zi-ming CAI Pei-zhong FENG Xue-qin KANG Farid AKHTAR Xiao-hong WANG School of Materials Science and Physics China University of Mining and TechnologyXuzhou 221116China School of Chemical Engineering and Technology China University of Mining and TechnologyXuzhou 221116China Division of Materials Science LuleåUniversity of TechnologyLuleå97187Sweden

Industrial spent MoSi_(2)-based materials were used to fabricate oxidation-resistant coatings on molybdenum via slurry painting in air. The microstructure, phase constituent and high-temperature oxidation behaviors of the coatings at 1500 ℃ were explored. The results show that the bonding layer is generated in the coatings after sintering,which strengthens the metallurgical combination between the coating and the substrate because of the formation of diffusion layers. Rare cracks appear in the coating using pure MoSi_(2)(PM coating) while the coating using spent MoSi_(2)(SM coating) is free of cracks due to decreased thermal expansion mismatch. After oxidation, the oxide scale of PM coating possesses large-sized pores while a relatively dense oxide scale is acquired by SM coating. Compared with PM coating, thinner glassy oxide scale with lower mass gain is obtained by SM coating, exhibiting better anti-oxidation properties at 1500 ℃.

关键词： recycling spent MoSi2 slurry painting anti-oxidation properties molybdenum substrate

Enhancement of Workability of Cement-Poor Concrete by Optimizing Paste Content

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Engineering（科研） 2014年第13期6卷 869-876页

作者： Mohammed Hatem Mohammed Nadhir Al-Ansari Sven Knutsson Deparment of Civil Environmental and Natural Resources Engineering Lule&aring University of Technology Lule&aring Sweden Department of Civil Engineering University of Mosul Mosul Iraq

This study describes the performance of concrete in fresh state, intended for sealing deep bore-holes in the host rock of radioactive repositories. Set of different paste volumes, combinations of water-to-powder ratios and fine aggregate contents have been performed within the frame of this study. The main objective was to search for tendencies, logical connections and phenomena that occur for different combination of materials regarding the fluidity and segregation and mainly the effect from the (paste) or fine aggregate content. It shall be pointed out that this investigation is a suggestion on how concrete can be optimized using two simple test methods based on changing the paste content. The results highlighted the importance of having sufficient amounts of filler and cement paste for separate and carry larger particles, which gives the concrete good workability and fluidity at casting. It was concluded that the slump behaviors can be optimized based on the adjustments of the superplastisizer dosage.

关键词： Concrete Paste Content Workability Talc Void Volume

Preface to special issue on frontiers of chemical engineering thermodynamics

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Chinese Journal of Chemical Engineering 2021年第3期34卷 1-1页

作者： Xiaoyan Ji Yuanhui Ji Xiaohua Lu luleåUniversity of Technology LuleåSweden Southeast University NanjingPR China Nanjing Tech University NanjingPR China

“Thermodynamics is the only physical theory of universal content concerning which I am convinced that,within the framework of the applicability of its basic concepts,it will never be overthrown.”—Albert Einstein Chemical Engineering plays an essential role in modern *** has been used to produce a wide variety of important materials,for example,the plastic drinking-water bottles,the jet fuels for transoceanic flights,and raw materials for assembling *** Engineering is also on the frontline to manufacture massive masks,gloves,testing kits,and vaccines to fight against COVID-19 globally.

关键词： frontier globally concerning

On a Non-Definite Sturm-Liouville Problem in the Two-Turning Point Case—Analysis and Numerical Results

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Journal of Applied Mathematics and Physics 2016年第9期4卷 1787-1810页

作者： Mervis Kikonko Department of Engineering Sciences and Mathematics Lule&aring University of Technology Lule&aring Sweden Department of Mathematics and Statistics The University of Zambia Lusaka Zambia

In this paper, we study the non-definite Sturm-Liouville problem comprising of a regular Sturm-Liouville equation and Dirichlet boundary conditions on a closed interval. We consider the case in which the weight function changes sign twice in the given interval of definition. We give detailed numerical results on the spectrum of the problem, from which we verify various results on general non definite Sturm-Liouville problems. We also present some theoretical results which support the numerical results. Some numerical results seem to be in contrast with the results that are so far obtained in the case where the weight function changes sign once. This leads to more open questions for future studies in this particular area.

关键词： Eigenvalue Eigenfunction Non-Definite Turning Point Richardson Number Richardson Index Haupt Index Oscillation Number Right-Definite Left-Definite

A Hybrid Statistical-Dynamical Downscaling of Air Temperature over Scandinavia Using the WRF Model

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Advances in Atmospheric Sciences 2020年第1期37卷 57-74页

作者： Jianfeng WANG Ricardo M.FONSECA Kendall RUTLEDGE Javier MARTÍN-TORRES Jun YU Department of Mathematics and Mathematical Statistics UmeåUniversitySE 90187UmeåSweden Group of Atmospheric Science Division of Space TechnologyDepartment of Computer ScienceElectrical and Space EngineeringLuleåUniversity of TechnologySE 97187 LuleåSweden Novia University of Applied Sciences PO BOX 6FI-65201 VaasaFinland Instituto Andaluz de Ciencias de la Tierra 18100 GranadaSpain The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry Institute for Planetary MaterialsOkayama University at MisasaTottori 682-0193Japan

An accurate simulation of air temperature at local scales is crucial for the vast majority of weather and climate *** this work,a hybrid statistical–dynamical downscaling method and a high-resolution dynamical-only downscaling method are applied to daily mean,minimum and maximum air temperatures to investigate the quality of localscale estimates produced by *** two downscaling approaches are evaluated using station observation data obtained from the Finnish Meteorological Institute over a near-coastal region of western *** dynamical downscaling is performed with the Weather Research and Forecasting(WRF)model,and the statistical downscaling method implemented is the Cumulative Distribution Function-transform(CDF-t).The CDF-t is trained using 20 years of WRF-downscaled Climate Forecast System Reanalysis data over the region at a 3-km spatial resolution for the central month of each *** performance of the two methods is assessed qualitatively,by inspection of quantile-quantile plots,and quantitatively,through the Cramer-von Mises,mean absolute error,and root-mean-square error *** hybrid approach is found to provide significantly more skillful forecasts of the observed daily mean and maximum air temperatures than those of the dynamical-only downscaling(for all seasons).The hybrid method proves to be less computationally expensive,and also to give more skillful temperature forecasts(at least for the Finnish near-coastal region).

关键词： WRF air temperature Cumulative Distribution Function-transform hybrid statistical–dynamical downscaling,model evaluation Scandinavian Peninsula

Modelling Dam Break Evolution over a Wet Bed with Smoothed Particle Hydrodynamics: A Parameter Study

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Engineering（科研） 2015年第5期7卷 248-260页

作者： Patrick Jonsson Par Jonsen Patrik Andreasson T.Staffan Lundstrom J.Gunnar I.Hellstrom Department of Engineering Sciences and Mathematics LuleåUniversity of TechnologyLuleaSweden

When investigating water flow in spillways and energy dissipation, it is important to know the behavior of the free surfaces. To capture the real dynamic behavior of the free surfaces is therefore crucial when performing simulations. Today, there is a lack in the possibility to model such phenomenon with traditional methods. Hence, this work focuses on a parameter study for one alternative simulation tool available, namely the meshfree, Lagrangian particle method Smoothed Particle Hydrodynamics (SPH). The parameter study includes the choice of equation-of-state (EOS), the artificial viscosity constants, using a dynamic versus a static smoothing length, SPH particle spatial resolution and the finite element method (FEM) mesh scaling of the boundaries. The two dimensional SPHERIC Benchmark test case of dam break evolution over a wet bed was used for comparison and validation. The numerical results generally showed a tendency of the wave front to be ahead of the experimental results, i.e. to have a greater wave front velocity. The choice of EOS, FEM mesh scaling as well as using a dynamic or a static smoothing length showed little or no significant effect on the outcome, though the SPH particle resolution and the choice of artificial viscosity constants had a major impact. A high particle resolution increased the number of flow features resolved for both choices of artificial viscosity constants, but at the expense of increasing the mean error. Furthermore, setting the artificial viscosity constants equal to unity for the coarser cases resulted in a highly viscous and unphysical solution, and thus the relation between the artificial viscosity constants and the particle resolution and its impact on the behavior of the fluid needed to be further investigated.

关键词： SPH Dam Break Smoothed Particle Hydrodynamics