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L^p Estimates of certain rough parametric Marcinkiewicz functions

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Frontiers of Mathematics in China 2019年第5期14卷 867-879页

作者： Laith HAWAWSHEH Ahmad AL-SALMAN School of Basic Sciences and Humanities German Jordanian UniversityAmmanJordan Department of Mathematics Sultan Qaboos UniversityP.O.Box 36Al-Khod 123 MuscatOman

We prove L^P estimates of a class of parametric Marcinkiewicz integral operators when their kernels satisfy only the L^1(S^n-1)integrability *** obtained L^P estimates resolve a problem left open in previous *** argument is based on duality technique and direct estimation of *** a consequence of our result,we deduce the L^P boundedness of a class of fractional Marcinkiewicz integral operators.

关键词： Marcinkiewicz integrals parametric Marcinkiewicz functions rough kernels Marcinkiewicz interpolation theorem

Soil substrate as a cascade of capillary barriers for conserving water in a desert environment:lessons learned from arid nature

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Journal of Arid Land 2014年第6期6卷 690-703页

作者： Ali Al-MAKTOUMI Said Al-ISMAILY Anvar KACIMOV Hamed Al-BUSAIDI Said Al-SAQRI Mansour Al-HADABI Department of Soils Water and Agricultural EngineeringSultan Qaboos UniversityPO Box 34 Al Khoud 123MuscatSultanate of Oman EcOman Centre Petroleum Development Oman LLC PO Box 81MuscatSultanate of Oman

Interaction between soil pedogenesis, subsurface water dynamics, climate, vegetation and human ingenuity in a desert environment has been found to result in a unique ecohydrological system with an essentially three dimensional sedimentation structure in the bed of a recharge dam in Oman. A 3-D array of silt blocks sand- wiched by dry sand-filled horizontal and vertical fractures was studied in pot experiments as a model of a natural prototype. Pots are filled with a homogenous sand-silt mixture （control） or artificially structured （smart design, SD） soil substrates. Rhodes grass and ivy （Ipomea, Convolvulaceae） were grown in the pots during the hottest season in Oman. Soil moisture content （SMC） was measured at different depths over a period of 20 days without irrigation. SD preserved the SMC of the root zone for both ivy and grass （SMC of around 25%-30% compared to 〈10% for control, 3 days after the last irrigation）. Even after 20 days, SMC was around 18% in the SD and 7% in the control. This, similar to the case of a natural prototype, is attributed to the higher upward capillary movement of water in control pots and intensive evaporation. The capillary barrier of sand sheaths causes discontinuity in moisture mi- gration from the micro-pores in the silt blocks to sand pores. The blocks serve as capillarity-locked water buffers, which are depleted at a slow rate by transpiration rather than evaporation from the soil surface. This creates a unique ecosystem with a dramatic difference in vegetation between SD-pots and control pots. Consequently, the Noy-Meir edaphic factor, conceptualizing the ecological impact of 1-D vertical heterogeneity of desert soils, should be generalized to incorporate 3-D soil heterogeneity patterns. This agro-engineering control of the soil substrate and soil moisture distribution and dynamics （SMDaD） can be widely used by desert farmers as a cheap technique, with significant savings of irrigation water.

关键词： soil capillary barrier infiltration soil heterogeneity ecohydrology hydropedology plant root soil moisture content

Structural evolution-enabled BiFeO3 modulated by strontium doping with enhanced dielectric,optical and superparamagnetic properties by a modified sol-gel method

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Chinese Physics B 2023年第3期32卷 521-530页

作者： Sharon V S Veena Gopalan E Malini K A Department of Physics Vimala College Thrissur-9 KeralaIndia

Multiferroic(BFO)nanoparticles doped with strontium with the general formula Bi1-xSrx FeO3(x=0,0.3,0.5,0.7)were synthesized using a modified sol-gel auto-combustion *** structural,electrical,optical,and magnetic properties of the samples are *** structural analysis,carried out using the x-ray powder diffraction technique,shows a structural transition from rhombohedral(R-3c)to cubic(Pm-3m)for the doping amount of strontium(Sr)equal to x=*** analysis of the prepared samples were carried out using scanning electron microscopy(SEM).Frequency-dependent dielectric constant and ac conductivity were *** doped samples,with improved dielectric properties,can be used to fabricate different optoelectronic *** dielectric dispersion and broad relaxation were exhibited by all the ***–Cole plots were employed as an effective tool to study the dispersion parameters,namely,the optical dielectric constant,static dielectric constant,relaxation time,and spreading *** activation energy was calculated from the relaxation peaks and Cole–Cole plots,which were found to be compatible with each *** bandgap of the samples was calculated using diffuse reflectance spectral(DRS)*** and strong photoluminescence in the IR region was observed in the samples,similar to ZnO,which was reported for the first ***-temperature and low-temperature magnetization studies point towards the superparamagnetic nature of the samples,with an improvement in magnetic properties with *** antiferromagnetic behavior of bulk bismuth ferrite transforms to superparamagnetic in nature for both pure and Sr-substituted bismuth ferrite nanoparticles due to the close dimensions of crystallite size with magnetic domains leading to the break-down of the frustrated spin cycloidal moment.

关键词： multiferroics sol-gel process x-ray spectra optical and dielectric properties

SIR model with time-varying contact rate

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International Journal of Biomathematics 2021年第4期14卷 27-47页

作者： Nasser Al-Salti Fatma Al-Musalhi Ibrahim Elmojtaba Vilmurugan Gandhi Department of Mathematics Sultan Qaboos University Po Box 36123 Al KhoudMuscatOman

The contact rate is defined as the average number of contacts adequate for disease transmission by an individual per unit time and it is usually assumed to be constant in ***,in reality,the contact rate is not always constant throughout the year due to different factors such as population behavior,environmental factors and many *** the case of serious diseases with a high level of infection,the population tends to reduce their contacts in the hope of reducing the risk of ***,it is more realistic to consider it to be a function of *** particular,the study of models with contact rates decreasing in time is well worth *** this paper,an SIR model with a time-varying contact rate is considered.A new form of a contact rate that decreases in time from its initial value till it reaches a certain level and then remains constant is *** proposed form includes two important parameters,which represent how far and how fast the contact rate is *** two parameters are found to play important roles in disease *** existence and local stability of the equilibria of the model are *** on the global stability of disease-free equilibrium and transcritical bifurcation are *** simulations are presented to illustrate the theoretical results and to demonstrate the effect of the model parameters related to the behavior of the contact rate on the model ***,comparisons between the constant,variable contact rate and variable contact rate with delay in response cases are presented.

关键词： Time varying contact rate SIR model global stability transcritical bifurcation

Hydrological and economic feasibility of mitigating a stressed coastal aquifer using managed aquifer recharge: a case study of Jamma aquifer, Oman

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Journal of Arid Land 2019年第1期11卷 148-159页

作者： Mustafa EL-RAWY Ali AL-MAKTOUMI Slim ZEKRI Osman ABDALLA Rashid AL-ABRI sultan qaboos university Civil Engineering Department Faculty of Engineering Shaqra University Department of Civil Engineering Faculty of Engineering Minia University Ministry of Regional Municipality and Water Resources Oman Water Society

This study explored the hydrological and economic feasibility of managed aquifer recharge(MAR) using tertiary treated wastewater(TWW) to mitigate salinity in the coastal aquifer of Jamma, Oman. A steady-state groundwater flow and transport model, using MODFLOW software, was developed and calibrated. Different managerial scenarios were simulated and the results reveal that the Jamma aquifer will be further deteriorated in the next 20 a if it remains unmanaged. The groundwater table will decline further by more than 3 m on average; and the iso-concentration salinity line of 1500 mg/L will advance 2.7 km inland, which will severely affect the farming activities in the area. However, MAR using TWW when integrated with the management of groundwater abstraction(e.g., using modern irrigation systems to reduce the abstraction rate) becomes hydrologically feasible to augment the aquifer storage and control seawater intrusion, and hence improves the farming activities. The results indicate that:(1) injecting TWW in the vicinity of irrigation wells(Scenario A2);(2) investing in smart water meters and online control of pumping from the wells to reduce the abstraction rate by 25%(Scenario B); and(3) a combination of both(Scenario B2) are feasible scenarios with positive net present values. Recharge in upstream areas is found not economically feasible because of the very high investment cost of the installation of pipes to transport the TWW over a distance of 12.5 km. Because of securing funds are challenging, Scenario B would be the best option and the second-best option is Scenario A2. Scenario B2 has the lowest net benefit investment ratio and is very attractive because it entails integrated demand and supply management of groundwater. It is required to reduce pumping and to invest in injecting TWW to improve groundwater quality in the vicinity of irrigation wells and to form a hydrological barrier to control seawater intrusion in the long run.

关键词： managed aquifer recharge treated wastewater salinity line coastal aquifer Oman

Review of recent trends in friction stir welding process of aluminum alloys and aluminum metal matrix composites

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Transactions of Nonferrous Metals Society of China 2021年第11期31卷 3281-3309页

作者： John VICTOR CHRISTY Abdel-Hamid ISMAIL MOURAD Muhammad M.SHERIF B.SHIVAMURTHY Mechanical Engineering Department College of EngineeringUnited Arab Emirates UniversityAl-AinP.O.Box.15551United Arab Emirates Mechanical Design Department Faculty of EngineeringHelwan UniversityCairoEgypt National Water and Energy Center United Arab Emirates UniversityAl Ain 15551United Arab Emirates Civil Construction and Environmental Engineering DepartmentCollege of EngineeringUniversity of Alabama–BirminghamBirminghamALUSA Department of Mechanical&Manufacturing Engineering Manipal Institute of TechnologyManipal Academy of Higher EducationManipalKarnatakaIndia

Welding is a vital component of several industries such as automotive,aerospace,robotics,and *** welding,these industries utilize aluminum alloys for the manufacturing of many components or ***,fusion welding of aluminum alloys is challenging due to several factors,including the presence of non-heat-treatable alloys,porosity,solidification,and liquation of *** manufacturers adopt conventional in-air friction stir welding(FSW)to weld metallic alloys and dissimilar *** researchers reported the drawbacks of this traditional in-air FSW technique in welding metallic and polymeric materials in general and aluminum alloys and aluminum matrix composites in specific.A number of FSW techniques were developed recently,such as underwater friction stir welding(UFSW),vibrational friction-stir welding(VFSW),and others,for welding of aluminum alloy joints to overcome the issues of welding using conventional ***,the main objective of this review is to summarize the recent trends in FSW process of aluminum alloys and aluminum metal matrix composites(Al MMCs).Also,it discusses the effect of welding parameters of the traditional and state-of-the-art developed FSW techniques on the welding quality and strength of aluminum alloys and Al *** among the techniques and advantages and limitations of each are *** review suggests that VFSW is a viable option for welding aluminum joints due to its energy efficiency,economic cost,and versatile modifications that can be employed based on the *** review also illustrated that significantly less attention has been paid to FSW of Al-MMCs and considerable attention is demanded to produce qualified joint.

关键词： aluminum alloys aluminum matrix composites traditional FSW techniques state-of-the-art FSW techniques microstructure mechanical properties

Marfan Syndrome with Systemic Lupus erythematosus

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TMR Integrative Nursing 2020年第5期4卷 172-175页

作者： Aisha Alshdefat Abdu Mueed Bidchol Abdalla Alshdaifat Rasha Abu Baker Department of Maternal and Child Health College of NursingSultan Qaboos UniversitySultanate of Oman Genetic Reporting Manager Al Ward Medical ServicesSultanate of Oman Medical Student University of LodzRepublic of Poland 不详

One of the autosomal dominant tissue disorders is Marfan syndrome that affects different organ ***,Marfan syndrome causing abnormalities in the heart,blood vessels,eyes,bones,and *** Often,features of Marfan syndrome are vision problems,defects in the large blood vessel-like aorta,tall and very thin,have long fingers and toes(arachnodactyly),and have an arm span exceeding the height of their ***,Other common features include a long and narrow face,crowded teeth,and scoliosis,or *** presented a thirty-three years old female known case of Systemic Lupus erythematosus(SLE)and had Marfan syndrome,presented to the emergency department with complaints of headache and fever for two *** patient denied any complaining of vomiting,blurred vision,dizziness.

关键词： Marfan Syndrome autosomal subdural subacute on chronic hemorrhage Systemic Lupus erythematosus