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Petroleum Science 2015年第1期12卷 170-176页

作者： talal al-wahaibi Yahya al-wahaibi Abdul-Aziz R.al-Hashmi Farouq S.Mjalli Safiya al-Hatmi Petroleum & Chemical Engineering Department College of Engineering Sultan Qaboos University

The effects of water content, shear rate, temperature, and solid particle concentration on viscosity reduction （VR） caused by forming stable emulsions were investigated using Omani heavy crude oil. The viscosity of the crude oil was initially measured with respect to shear rates at different temperatures from 20 to 70℃. The crude oil exhibited a shear thinning behavior at all the temperatures. The strongest shear thinning was observed at 20℃. A non-ionic water soluble surfactant （Triton X-100） was used to form and stabilize crude oil emulsions. The emulsification process has significantly reduced the crude oil viscosity. The degree of VR was found to increase with an increase in water content and reach its maximum value at 50 % water content. The phase inversion from oil- oil emulsion occurred at 30 in-water emulsion to water-in- % water content. The results indicated that the VR was inversely proportional to temperature and concentration of silica nanoparticles. For water-in-oil emulsions, VR increased with shear rate and eventually reached a plateau at a shear rate of around 350 s^-1. This was attributed to the thinning behavior of the continuous phase. The VR of oil-in-water emulsions remained almost constant as the shear rate increased due to the Newtonian behavior of water, the continuous phase.

关键词： Viscosity reduction Phase inversion Non-newtonian fluid Oil-in-water emulsions Heavy crude oil

Normal and abnormal grain growth in magnesium:Experimental observations and simulations

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Journal of Materials Science & Technology 2020年第15期47卷 257-270页

作者： Risheng Pei Sandra Korte-Kerzel talal al-Samman Institut fur Metallkunde und Materialphysik RWTH Aachen UniversityD-52056AachenGermany

Commercial purity as-cast magnesium was hot rolled and subsequently annealed at different temperatures in order to investigate its grain growth behavior and link it to the texture *** at an intermediate temperature of 220℃ gave rise to abnormal grain growth with a few grains reaching a grain diameter 10 times larger than the *** the annealing temperature to 350℃ yielded normal grain *** types of grain growth revealed a strengthening of the(0001) texture *** is hypothesized that a dislocation density gradient after recrystallization grants(0001) grains a size advantage during early stages of *** type of growth will be,however,determined by the mobility of the present grain boundaries and triple junction drag,which are strongly dependent on the annealing *** above hypothesis of the interplay between these parameters was explored through curvature-and re sidual dislocation-density-gradient-driven grain growth simulations using a formerly developed level-set *** simulation outcome suggests that application of such a modeling approach in microstructure studies of magnesium can provide valuable new insights into the problem of grain growth and associated texture evolutio n.

关键词： Pure magnesium Grain growth Texture Dislocation density gradient Level-set modeling

Deformation behaviour of magnesium bicrystals with symmetrical 90°<1120>tilt grain boundaries analysed by large area EBSD mapping

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Journal of Magnesium and alloys 2023年第5期11卷 1556-1566页

作者： Kevin Bissa talal al-Samman Dmitri A.Molodov Institute of Physical Metallurgy and Materials Physics RWTH Aachen University52056AachenGermany International Research Organization for Advanced Science and Technology(IROAST) Kumamoto UniversityKumamoto 860-8555Japan

Grain boundaries play a significant role in the deformation of *** response to deformation is however not completely understood,particularly with respect to how they accommodate lattice rotation of adjoining crystallites by changing their structure and *** current study thus investigates the deformation behaviour of Mg bicrystals with 90°symmetric tilt boundary strained in plane-strain compression up to different final *** to the initial soft orientation of the two crystals,activation of basal slip in each crystal gave rise to lattice rotation around the transverse direction towards the compression direction of the *** of single EBSD maps with a small step size were obtained from the GB region and stitched together to produce large panoramic maps of a macroscopic *** very time-consuming,this technique has proven useful in clarifying the origin of the non-uniform deformation zones in the vicinity of the grain boundary and explains the mechanisms,by which the grain boundary was able to cope with the imposed strain before ***,several variants of extension twins were observed as an additional deformation mechanism despite having negative Schmid *** investigation of their resulting combined shear components with respect to the sample coordinate system revealed an alignment along the longitudinal direction of the channel-die,therefore justifying their nucleation.

关键词： Panorama EBSD Plain strain compression Lattice rotation Magnesium bicrystal Anomalous twins

Optimization of acid fracturing for a tight carbonate reservoir

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Petroleum 2020年第1期6卷 70-79页

作者： Aymen al-Ameri talal Gamadi Bob L.Herd Department of Petroleum Engineering Texas Tech University2500 BroadwayLubbockTX79409USA

In this study,acid fracturing treatments were simulated for a tight limestone reservoir within a shale formation using FRACPRO *** purpose was to investigate the optimum acid fracturing design that leads to a higher fracture etched length and width,and higher fracture ***,the impact of the rock-acid contact time and whether to consider a post-flush or fluids flowback,on the acid fracturing outcomes were also investigated.A simple geological model was constructed which consists of different lithological *** acid fracturing design scenarios were considered starting from a single stage of acid injection to multi-stage *** multi-stage acid treatment,alternate acid-slickwater injection was *** HCl acids with different concentrations and other acids that are already included in FRACPRO database were *** results showed that the acid loss during post-flush is among the main problems of the acid fracturing in tight carbonate shale *** the single stage of acid injection,it is recommended to flow back the acid after well shut-in instead of considering a post-flush *** multi-stage alternate acid slickwater injection reduces or even eliminated the acid ***,it is recommended to inject a slickwater before well shut-in to reduce the rock-acid contact time,thus reducing the formation *** results also showed that the created fracture etched width decreases and the fracture etched length increases as the fracturing stages *** this study,because of the low carbonate layer permeability and compressive strength,a two-stage alternate 28%HCl and slickwater injection with a post-flush stage is recommended.

关键词： Acid fracturing Tight carbonate Acid loss Low compressive strength Single stage acid fracturing Multi-stage acid fracturing

High temperature deformation and recrystallization behavior of magnesium bicrystals with 90°<1010>and 90°<1120>tilt grain boundaries

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Journal of Magnesium and alloys 2024年第2期12卷 625-638页

作者： Kevin Bissa talal al-Samman Dmitri A.Molodov Institute of Physical Metallurgy and Materials Physics RWTH Aachen University52056 AachenGermany International Research Organization for Advanced Science and Technology(IROAST) Kumamoto UniversityKumamoto 860-8555Japan

The deformation mechanisms and dynamic recrystallization(DRX)behavior of specifically grown bicrystals with a symmetric 90°and 90°tilt grain boundary,respectively,were investigated under deformation in plane strain compression at 200℃and 400℃.The microstructures were analyzed by panoramic optical microscopy and large-area electron backscatter diffraction(EBSD)orientation *** analysis employed a meticulous approach utilizing hundreds of individual,small EBSD maps with a small step size that were stitched together to provide comprehensive access to orientation and misorientation data on a macroscopic *** slip primarily governed the early stages of deformation at the two temperatures,and the resulting shear induced lattice rotation around the transverse direction(TD)of the *** existence of the grain boundary gave rise to dislocation pile-up in its vicinity,leading to much larger TD-lattice rotations within the boundary region compared to the *** increasing temperature,the deformation was generally more uniform towards the bulk due to enhanced dislocation mobility and more uniform stress *** recrystallization at 200℃was initiated in{1011}-compression twins at strains of 40%and *** 400℃,DRX consumed the entire grain boundary region and gradually replaced the deformed microstructure with progressing *** recrystallized grains displayed characteristic orientations,such that their c-axes were perpendicular to the TD and additionally scattered between 0°and 60°from the loading *** recrystallized grains displayed mutual rotations of up to 30°around the c-axes of the initial grains,forming a discernible basal fiber texture component,prominently visible in the{1120}pole *** is noteworthy that the deformation and DRX behaviors of the two analyzed bicrystals exhibited marginal variations in response to strain and deformation temperature.

关键词： Elevated deformation temperatures Plain strain compression Magnesium bicrystals Panorama EBSD Dynamic Recrystallization

Solute drag-controlled grain growth in magnesium investigated by quasi in-situ orientation mapping and level-set simulations

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Journal of Magnesium and alloys 2023年第7期11卷 2312-2325页

作者： Risheng Pei Yujun Zhao Muhammad Zubair Sangbong Yi talal al-Samman Institut für Metallkunde und Materialphysik RWTH Aachen University52056 AachenGermany Institute of Materials and Process Design Helmholtz-Zentrum Hereon21502 GeesthachtGermany Department of Metallurgical and Materials Engineering Faculty of ChemicalMetallurgical&Polymer EngineeringUniversity of Engineering&Technology(UET)LahorePakistan Institute for Materials Ruhr-Universität Bochum44801 BochumGermany

Critical properties of metallic materials,such as the yield stress,corrosion resistance and ductility depend on the microstructure and its grain size and size *** atoms that favorably segregate to grain boundaries produce a pinning atmosphere that exerts a drag pressure on the boundary motion,which strongly affects the grain growth behavior during *** the current work,the characteristics of grain growth in an annealed Mg-1 wt.%Mn-1 wt.%Nd magnesium alloy were investigated by advanced experimental and modeling *** quasi in-situ orientation mappings with a scanning electron microscope were performed to track the evolution of local and global microstructural characteristics as a function of annealing *** segregation at targeted grain boundaries was measured using three-dimensional atom probe ***-set computer simulations were carried with different setups of driving forces to explore their contribution to the microstructure development with and without solute *** results showed that the favorable growth advantage for some grains leading to a transient stage of abnormal grain growth is controlled by several drivers with varying importance at different stages of *** longer annealing times,residual dislocation density gradients between large and smaller grains are no longer important,which leads to microstructure stability due to predominant solute *** fluctuations in residual dislocation energy and solute concentration near grain boundaries cause different boundary segments to migrate at different rates,which affects the average growth rate of large grains and their evolved shape.

关键词： Magnesium alloys Grain growth Quasi in-situ EBSD Level-set simulation Solute drag Dislocation density gradient

Development of PCCNN-Based Network Intrusion Detection System for EDGE Computing

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Computers, Materials & Continua 2022年第4期71卷 1769-1788页

作者： Mohd Anul Haq Mohd Abdul Rahim Khan talal al-Harbi Department of Computer Science College of Computer and Information SciencesMajmaah UniversityAl-Majmaah 11952Saudi Arabia

Intrusion Detection System(IDS)plays a crucial role in detecting and identifying the DoS and DDoS type of attacks on IoT ***,anomaly-based techniques do not provide acceptable accuracy for efficacious intrusion ***,we found many difficulty levels when applying IDS to IoT devices for identifying attempted *** this background,we designed a solution to detect intrusions using the Convolutional Neural Network(CNN)for Enhanced Data rates for GSM Evolution(EDGE)*** created two separate categories to handle the attack and non-attack events in the *** findings of this study indicate that this approach was significantly *** attempted both multiclass and binary *** the case of binary,we clustered all malicious traffic data in a single ***,we developed 13 layers of Sequential 1-D CNN for IDS detection and assessed them on the public dataset *** Component Analysis(PCA)was implemented to decrease the size of the feature vector based on feature extraction and *** approach proposed in the current investigation obtained accuracies of 99.34%and 99.13%for binary and multiclass classification,respectively,for the NSL-KDD *** experimental outcomes showed that the proposed Principal Component-based Convolution Neural Network(PCCNN)approach achieved greater precision based on deep learning and has potential use in modern intrusion detection for IoT systems.

关键词： IDS edge computing machine learning NSL-KDD IoT

Effects of Ca and Nd addition on plastic instability in extruded Mg-Mn alloy deformed under various conditions

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Journal of Magnesium and alloys 2023年第2期11卷 543-552页

作者： Sang Kyu Woo Risheng Pei talal al-Samman Dietmar Letzig Sangbong Yi Institute of Materials and Process Design Helmholtz-Zentrum hereon21502 GeesthachtGermany Institut für Metallkunde und Materialphysik RWTH Aachen University52056 AachenGermany

Plastic instability, called Portevin-Le-Chatelier(PLC) effect, manifests itself as an unstable plastic flow during tensile tests of structural materials. This phenomenon has a strong influence on diverse properties, leading to unexpected vulnerabilities in the service *** various magnesium-based alloys, PLC phenomenon is most prominently observed in the Mg-Mn-Nd alloy under elevated temperature and low strain rate conditions. An important aim of the study is to clarify and compare the significance of the RE and Ca addition, which are known to cause a formation of a largely weakened non-basal type texture, in the occurrence of plastic instability. Due to the PLC phenomenon, there is a risk of weakening texture and formability improvement by the addition of RE and Ca elements in Mg alloys. Based on the understanding of the role of Nd to the PLC phenomenon in Mg-Mn alloy identified in previous studies, the PLC characteristics according to alloying elements and deformation conditions were compared and analyzed. To identify the micromechanical mechanisms of the PLC phenomenon, varies in the microstructure and mechanical properties during deformation of Mg-Mn binary and Ca or Nd-containing Mg-Mn-based ternary alloys in various conditions were systemically analyzed. The addition of Ca did not show a marked PLC effect due to the formation of low number density Mn-Ca and Ca-Ca solute clusters and an unbalanced Mn:Ca ratio. In contrast, the addition of Nd leads to the formation of a higher number density of Nd-Nd and Mn-Nd solute clusters than that of Ca-Ca and Mn-Ca solute clusters of the Mg-Mn-Ca alloy, resulting in a stable solute-dislocation interaction atmosphere under specific ranges of deformation temperature and strain rate. The deformation in the regime of PLC phenomenon, results in a decrease in ductility and an increase in strength, despite deformation at elevated temperatures with maintaining the weakened texture.

关键词： Magnesium Plastic instability Portevin-Le Chatelier effect Solute cluster Neodymium Calcium

Plastic instability and texture modification in extruded Mg-Mn-Nd alloy

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Journal of Magnesium and alloys 2022年第1期10卷 160-174页

作者： Sang Kyu Woo Risheng Pei talal al-Samman Dietmar Letzig Sangbong Yi Magic-Magnesium Innovation Center Institute for Materials and Process DesignHelmholtz-Zentrum GeesthachtGeesthacht 21502Germany Institut für Metallkunde und Materialphysik RWTH Aachen UniversityAachen 52056Germany

Even though Mg alloys containing Mn and rare earth elements lead to higher ductility and lower yield asymmetry due to the weak texture after extrusion, plastic instability, commonly known as the Portevin–Le Chatelier(PLC) effect, causes unexpected fragility in the service environment. In the present study, the PLC phenomenon and texture development during the deformation of Mg-Mn and Mg-Mn-Nd extruded alloys were investigated under various temperatures and strain rates. The addition of Nd causes not only texture weakening but also severe PLC phenomenon. The PLC phenomenon was significantly affected by the temperatures and the strain rates, which causes a difference in mechanical properties and development of texture. In the conditions of high temperature and low strain rate, the strength increased while the elongation decreased significantly, and obvious PLC phenomenon with severe serration and negative strain rate sensitivity. The initial texture was maintained even after deformation only under severe PLC conditions, and this is due to the restriction of basal slip and suppression of lattice rotation in PLC conditions. The series of results indicate that the PLC phenomenon causes a reduction of formability even at high temperature.

关键词： Magnesium Plastic instability Portevin–Le Chatelier effect Manganese Neodymium Texture

Potential reduction in water consumption of greenhouse evaporative coolers in arid areas via earth-tube heat exchangers

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Journal of Arid Land 2021年第4期13卷 388-396页

作者： Abdulrahim M al-ISMAILI Moustafa A FADEL Hemantha JAYASURIYA L H Janitha JEEWANTHA Adel al-MAHDOURI talal al-SHUKEILI Department of Soils Water and Agricultural EngineeringSultan Qaboos UniversityMuscat PC123Oman Department of Arid land Agriculture United Arab Emirates UniversityAl-Ain 17555United Arab Emirates Centre for Future Materials&School of Mechanical and Electrical Engineering University of Southern QueenslandToowoomba QLD 4350Australia

This study aimed to explore the potential of developing a novel cooling system combining a greenhouse and an earth-tube heat exchanger(ETHE).In this system,greenhouse air is circulated through the underneath soil mass to use the deep-soil cooling *** was achieved through the following ***,soil temperature profile inside and outside the cultivated greenhouse was monitored for almost one year to study the possibility of using deep-soil coldness for cooling the greenhouse ***,a prototype ETHE was built to practically investigate the potential reduction in air temperature as the air flows inside the deep earth ***,a prototype greenhouse was erected to study the ETHE *** from the first experiment revealed that soil temperature at a soil depth of 2.5 m inside the greenhouse offers good conditions to bury the *** soil temperature at this soil depth was below the maximum temperature(32℃)that most greenhouse crops can *** from the prototype ETHE showed a slight reduction in air temperature as it passed through the *** the prototype of the integrated greenhouse and ETHE system,reduction in air temperature was observed as the air passed through the ETHE *** night,the air was heated up across the ETHE pipes,indicating that the ETHE was working as a *** concluded from this study that greenhouses in arid climates can be cooled using the ETHE concept which would save a large amount of water that would otherwise be consumed in the evaporative *** investigations are highly encouraged.

关键词： earth-tube heat exchanger greenhouse fan-pad cooling system water saving arid areas