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Investigation into improving the efficiency and accuracy of CFD/DEM simulations

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Particuology 2014年第5期12卷 41-53页

作者： falah alobaid Nabil Baraki Bernd Epple TU Darmstadt Energiesysteme und EnergietechnikPetersenstrasse 3064287 DarmstadtGermany

The Euler-Lagrange approach combined with a discrete element method has frequently been applied to elucidate the hydrodynamic behavior of dense fluid-solid flows in fluidized beds. In this work, the efficiency and accuracy of this model are investigated. Parameter studies are performed; in these studies, the stiffness coefficient, the fluid time step and the processor number are varied under conditions with different numbers of particles and different particle diameters. The obtained results are compared with measurements to derive the optimum parameters for CFD/DEM simulations. The results suggest that the application of higher stiffness coefficients slightly improves the simulation accuracy. However, the average computing time increases exponentially. At larger fluid time steps, the results show that the average computation time is independent of the applied fluid time step whereas the simulation accuracy decreases greatly with increasing the fluid time step. The use of smaller time steps leads to negligible improvements in the simulation accuracy but results in an exponential rise in the average computing time. The parallelization accelerates the DEM simulations if the critical number for the domain decomposition is not reached. Above this number, the performance is no longer proportional to the number of processors. The critical number for the domain decomposition depends on the number of particles. An increase in solid contents results in a shift of the critical decomposition number to higher numbers of CPUs.

关键词： Computational fluid dynamics Discrete element method Stiffness coefficient Fluid time step Parallelization

Comparison of three different CFD methods for dense fluidized beds and validation by a cold flow experiment

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Particuology 2016年第6期14卷 34-47页

作者： Alexander Stroh falah alobaid Max Thomas Hasenzahl] Jochen Hilz Jochen Strohle Bernd Epple Technische Universitdt Darmstadt Institute for Energy Systems and Technology Otto-Berndt-Straβe 2 64287 Darmstadt Germany

This work focuses on a comparison between three different numerical CFD methods, namely Euler-Euler, Euler-Lagrange-stochastic, and Euler-Lagrange-deterministic, to treat a dense spouted bed, A simple cold flow experiment was used to investigate the hydrodynamics of a gas-solid flow in a three dimensional lab-scale spouted bed, In this context, two different air mass flow rates, 0,005 and 0.006 kg/s, were applied during fluidization. The experimental bed behaviour was recorded with a high-speed camera to validate the numerical predictions in terms of bubble size, bed expansion rate, and particle velocities at different reactor heights. The numerical setup was kept similar between all three modelling approaches, At both gas mass flow rates all three approaches are able to capture the overall bed expansion. However, at higher gas mass flow rates, discrepancies between experiment and simulation increase for the Euler-Euler and Euler-Lagrange-stochastic models. The Euler-Lagrange deterministic model most accurately predicts the flow pattern at both mass flow rates. The main reasons for discrepancies between simulation and experiment result from modelling of the collision and friction forces.

关键词： Computational fluid dynamics Euler-Lagrange-deterministic collisionmodel Euler-EulerMP-PIC approach Experimental validation

A Review of Rechargeable Zinc-Air Batteries:Recent Progress and Future Perspectives

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Nano-Micro Letters 2024年第7期16卷 358-401页

作者： Ghazanfar Nazir Adeela Rehman Jong-Hoon Lee Choong-Hee Kim Jagadis Gautam Kwang Heo Sajjad Hussain Muhammad Ikram Abeer Aalobaid Seul-Yi Lee Soo-Jin Park Department of Nanotechnology and Advanced Materials Engineering Hybrid Materials Research Center(HMC)Sejong UniversitySeoul 05006Republic of Korea Department of Chemical and Biomolecular Engineering Yonsei University50 Yonsei-RoSeodaemun-GuSeoul 03722Republic of Korea Department of Chemistry Inha UniversityIncheon 22212Republic of Korea Solar Cell Applications Research Lab Department of PhysicsGovernment College University LahoreLahore 54000 PunjabPakistan Department of Chemistry College of ScienceKing Saud UniversityP.O.Box 2455Riyadh 11451Saudi Arabia

Zinc-air batteries(ZABs)are gaining attention as an ideal option for various applications requiring high-capacity batteries,such as portable electronics,electric vehicles,and renewable energy *** offer advantages such as low environmental impact,enhanced safety compared to Li-ion batteries,and cost-effectiveness due to the abundance of ***,early research faced challenges due to parasitic reactions at the zinc anode and slow oxygen redox *** advancements in restructuring the anode,utilizing alternative electrolytes,and developing bifunctional oxygen catalysts have significantly improved *** have achieved battery reversibility over thousands of cycles,introduced new electrolytes,and achieved energy efficiency records surpassing 70%.Despite these achievements,there are challenges related to lower power density,shorter lifespan,and air electrode corrosion leading to performance *** review paper discusses different battery configurations,and reaction mechanisms for electrically and mechanically rechargeable ZABs,and proposes remedies to enhance overall battery *** paper also explores recent advancements,applications,and the future prospects of electrically/mechanically rechargeable ZABs.

关键词： Zinc-air batteries Energy storage Affordability Reversibility

Structural,magnetic,electrical and microwave properties of spinel ferrites

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Journal of Rare Earths 2022年第3期40卷 443-450,I0003页

作者： Salma Aman Naseeb Ahmad M.H.Alhossainy Hind Albalawi Manal Morsi Tahani I.Al-Muhimeed Abeer A.alobaid Department of Physics Khwaja Fareed University of Engineering and Information TechnologyAbu Dhabi RoadRahim Yar Khan64200Pakistan Department of Physics Faculty of ScienceTaibah UniversityMedinaSaudi Arabia Department of Physics College of SciencePrincess Nourah bint Abdulrahman University11671RiyadhSaudi Arabia Department of Physics College of Arts and SciencePrince Sattam Bin Abdulaziz UniversityRiyadhWadi AddawasirSaudi Arabia Department of Chemistry College of ScienceKing Saud UniversityP.O.Box 22452Riyadh11495Saudi Arabia

The ferrite series having formulation SrYb_(y)Fe_(2-y)O_(4)(y=0.00 to 0.10)were synthesized via the sol-gel *** involvement of the yttrium in the base produces several changes in the structural,magnetic,and electrical performance of the *** of structural parameters was done through X-ray *** samples have cubic structures confirmed from X-ray *** coercivity of sample enlarges with the involvement of Yb-ions while their saturation and remanence magnetization values *** the concentration of Yb-ion increases in the lattice,the real and imaginary values of permittivity *** increased content of Yb enhances the impedance *** analysis of the M vs H loop was finished under the fixed range of−2 to+2 *** using 0.5-12 GHz frequency,the microwave measurements of all the sample were *** dispersion of frequency of ferrites is responsible for the natural magnetic resonance phenomenon and the domain wall *** evaluated features of synthesized sample show their appropriateness for microwave absorption appliances.

关键词： Microwave absorption Dielectric constant Conductivity Magnetization Impedance Rare earths

Nasal Dermoid Cyst: A Case Report

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International Journal of Otolaryngology and Head & Neck Surgery 2023年第5期12卷 358-363页

作者： Yazeed Alghonaim Nawaf Alfayez Fahad alobaid Division of Otolaryngology-Head and Neck Surgery Department of Surgery King Abdulaziz Medical City Riyadh Saudi Arabia Division of Otolaryngology-Head and Neck Surgery Department of Surgery University of Saskatchewan Saskatoon Canada

Nasal dermoid sinus cysts (NDSCs) are rare neoplasms in the median line of the nasofrontal area. Unlike other dermoid cysts, a NDSC can manifest as a cyst, sinus, or fistula, and may extend intracranially. Nasal dermoid cysts usually present at birth and are commonly diagnosed by 3 years of age. An incidentally detected nasal dermoid cyst in an adult patient is extremely rare. In this case, a 23-year-old female with a history of intermittent serous thick discharge from a pit in the nasal columella since early childhood. Examination of the nasal cavity showed mild septal deviation to the left side, dorsal hump, wide nasal bone, a small pit-sinus at the columella, over projected nose, and wide bulbous down rotated nasal tip. The findings were suggesting nasal dermoid cyst, so a magnetic resonance imaging (MRI) was done for the patient to confirm the diagnosis. The MRI findings showed that there are 3 small cysts at the nasal septum anteriorly with a small fistula connecting the anterior inferior 2 cysts with no involvement to the intracranial cerebrospinal fluid (CSF) space. During the surgery, an open rhinoplasty approach was used. The trans-columellar incision was made around the fistula, and the tract was identified using a lacrimal probe and methylene blue. The dissection around the tract was continued until the sac was identified in the area of the membranous septum, and it was removed and sent for histopathology. The surgery then continued in a regular full rhinoplasty fashion. In conclusion, dermoid cyst of the nasal septum is a rare congenital lesion, especially in adults. After a thorough history taking and physical examination, a preoperative high-resolution axial and coronal CT and/or MRI is essential for diagnostic and operative planning. The treatment of choice for nasal dermoid cysts is complete surgical excision with clear margins. Surgical strategies usually depend on the location and extent of the lesion. Recurrence is uncommon and often easily manage

关键词： Dermoid Cyst Rhinoplasty Nasal Dermoid Cyst Rhinology Case Report

Diabetes mellitus is not associated with worse short term outcome in patients older than 65 years old post-liver transplantation

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World Journal of Hepatology 2023年第2期15卷 274-281页

作者： Saad Alghamdi Shaden Alamro Dhari alobaid Elwy Soliman Ali Albenmousa Khalid Ibrahim Bzeizi Saleh Alabbad Saleh A Alqahtani Dieter Broering Waleed Al-Hamoudi Liver and Small Bowel Health Centre Department KFSHRCRiyadh 11211Saudi Arabia Department of Medicine KFSHRCRiyadh 11211Saudi Arabia Department of Internal Medicine Minia UniversityMinya 61519Egypt Division of Gastroenterology and Hepatology Johns Hopkins UniversityBaltimoreMD 21287United States Liver Disease Research Center Department of MedicineCollege of MedicineKing Saud UniversityRiyadh 11451Saudi Arabia

BACKGROUND Non-alcoholic fatty liver disease is a global health care challenge and a leading indication of liver transplantation(LT).Hence,more patients with diabetes mellitus(DM)are undergoing LT,especially,above the age of *** To evaluate the impact of DM on short-term outcomes post-LT in patients over the age of *** We collected data of patients who underwent LT from January 2001 until December 2019 using our electronic medical *** assessed the impact of DM on short-term outcomes,one-year,post-LT based on the following variables:Survival at one year;acute cellular rejection(ACR)rates;intensive care unit(ICU)and hospital length of stay;and *** Total of 148 patients who are 65 year or older underwent LT during the study *** mean age is 68.5±3.3 years and 67.6%were *** median Model for End-stage Liver Disease score at time of transplantation was 22(6-39),39%of patients had hepatocellular carcinoma and 77.7%underwent living donor *** one-year survival was similar between DM patients and others,91%.ACR occurred in 13.5%of patients(P=0.902).The median ICU stay is 4.5-day P=*** rates of ICU and 90-d readmission were similar(P=0.821)and(P=0.194),*** The short-term outcome of elderly diabetic patients undergoing LT is similar to *** presence of DM in elderly LT candidates should not discourage physicians from transplant consideration in this cohort of patients.

关键词： Acute cellular rejection Diabetes mellitus Elderly Graft survival Liver transplantation

Synoptic review on existing and potential sources for bias in dental research methodology with methods on their prevention and remedies

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World Journal of Methodology 2023年第5期13卷 426-438页

作者： Amit Arvind Agrawal Nilima Prakash Mohammad Almagbol Mohammed alobaid Abdullah Alqarni Hammam Altamni Department of Peridontology and Implantology Mahatma Gandhi Vidyamandir’s Karmaveer Bhausaheb Hiray Dental College and HospitalNasik 422003MaharashtraIndia Department of Oral and Maxillofacial Pathology Mahatma Gandhi Vidyamandir’s Karmaveer Bhausaheb Hiray Dental College and HospitalNashik 422003MaharashtraIndia Department of Periodontics Community Dental Sciences King Khalid UniversityAbha 62217Saudi Arabia Department of Restorative Dental Science and Dental Education King Khalid UniversityAbha 62217Saudi Arabia Department of Diagnostics Sciences and Oral Biology King Khalid UniversityAbha 62217Saudi Arabia Department of Orthodontic Assir Specialist Dental CenterAbhaMinistry of HealthAbha 62217Saudi Arabia

The results of years of dental study serve as the foundation for the practise of medicine and,for that matter,*** may have their own preferences for techniques and materials,but whether directly or indirectly,their decisions are influenced by systematic reviews and ***,due to poorly conducted or presented research,this very basic foundation may not be *** in research is one of several factors that might make study results or research itself *** can be introduced into research at many stages,deliberately or *** can appear at any point during the research process,even before the study itself *** are many biases in research,but some of them are more relevant to dentistry research than *** it is said that“eyes see what the mind knows”,it is essential to have a complete understanding of the different types of bias,how and when they get entrenched,and what steps may be taken to prevent or lessen them if they do *** comprehensive summary of bias in dentistry research is provided by this synoptic *** goal is to identify gaps and measures that have been taken-or that should have been taken-by providing both descriptive and evaluative summaries,as well as examples from the literature,when needed.

关键词： Dental research Bias(epidemiology) Research methodology Research design Epidemiologic methods

Mobile Based IoT Solution for Helping Visual Impairment Users

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Advances in Internet of Things 2021年第4期11卷 141-152页

作者： Hussein Abdel-Jaber Hussein Albazar Ahmed Abdel-Wahab Malak El Amir Areej Alqahtani Mohammed alobaid Faculty of Computer Studies Arab Open University Riyadh Saudi Arabia Systems and Computers Engineering Faculty of Engineering Al-Azhar University Cairo Egypt

Blind people have many tasks to do in their lives. However, blindness generates challenges for them to perform their tasks. Many blind persons use a traditional stick to move around and to perform their tasks. But the obstacles are not detected in traditional stick, it is ineffective for visually impaired people. The blind person has no idea what kind of objects or obstacles are in front of him/her. The blind person has no idea what size the object is or how far away he or she is from it. It is difficult for a blind person to get around. To assist people with vision impairment by making many of their daily tasks simple, comfortable, and organized, they will be able to recognize anything (an obstacle for blind people). A smart stick with mobile application can be used. One of the solutions is a mobile-based Internet of Things solution, which is a stick intended to assist visually impaired people to navigate more easily. It enables blindness and low vision people to navigate and carry out their daily tasks with ease and comfort. A technologically advanced blind stick that enables visually impaired people to move with ease. This paper proposes a system of software and hardware that helps visually impairment people to find their ways in an easy and comfortable way. The proposed system uses smart stick and mobile application to help blind and visually impaired people to identify objects (such as walls, tables, vehicles, people, etc.) in their ways, this can enable them to avoid these objects. In addition, as a result, the system will notify the user through sound from the smartphone. Finally, if he/she gets lost, he will be able to send an SMS with his/her GPS location.

关键词： IoT Ultrasonic Sensor Obstacle Detection GPS Smart Stick Arduino