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Numerical investigation to evaluate the effects of gravity and pressure on flame structure and soot formation of turbulent non-premixed methaneair flame

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Propulsion and Power Research 2022年第4期11卷 473-495页

作者： Subrat Garnayak Amjad Ali Pasha radi Alsulami Medhat A.Nemitallah Abdul Gani Abdul Jameel Sukanta K.Dash V.Mahendra Reddy School of Energy Science&Engineering Indian Institute of Technology KharagpurWest Bengal721302India Department of Aerospace Engineering King Abdulaziz UniversityJeddah21589Saudi Arabia Department of Mechanical Engineering King Abdulaziz UniversityJeddah21589Saudi Arabia IRC-Hydrogen and Energy Storage and Mechanical Engineering Department King Fahd University of Petroleum and MineralsDhahran31261Saudi Arabia Department of Chemical Engineering King Fahd University of Petroleum and MineralsDhahran31261Saudi Arabia Center for Refining&Advanced Chemicals King Fahd University of Petroleum and MineralsDhahran31261Saudi Arabia Department of Mechanical Engineering Indian Institute of Technology KharagpurWest Bengal721302India

In this study,a turbulent non-premixed(diffusion)methane-air flame has been investigated computationally to analyze the influences of pressure and gravity on flame structure and sooting characteristics between 1 and 10 *** simulation has been conducted in a 2-D axisymmetric computational domain using the finite volume-based computational fluid dynamics(CFD)*** interaction of turbulence and chemistry is modeled by considering the steady laminar flamelet model(SLFM)and the GRI Mech 3.0 chemical *** radiative heat transfer calculation is carried out by considering the discrete ordinate(DO)method and the weighted sum grey gas model(WSGGM).The semi-empirical Moss-Brookes model is considered to calculate *** impact of gravity on flame and sooting characteristics are evaluated by comparing the normal-gravity flames with the zero-gravity *** effect of soot and radiation on flame temperature is also *** results show a close agreement with the measurement when both soot and radiation are included in the numerical *** rates of soot formation,surface growth,and oxidation increase with increased operating pressure,regardless of ***-gravity flames have a higher soot volume fraction,a wider soot-containing zone,a higher CO mass fraction,and a lower flame temperature than normal-gravity flames while maintaining constant *** normal-gravity flames,the CO mass fraction decreases with pressure,whereas it increases with pressure rise in flames of zero *** of zero gravity appear taller and broader compared to the flames of normalgravity for a fixed *** increase in pressure significantly reduces the flame length and width in normal-gravity ***,the pressure elevation has little effect on the shape of a zero-gravity *** outcomes of the present study will assist in fully understanding the combustion and sooting characteristics of turbulent diffusion flames that will help design and develop h

关键词： Computational fluid dynamics(CFD) Flamelet Gravity Pressure Soot

Improving the Thermal Efficiency and Performance of Refrigeration Systems:Numerical-Experimental Analysis of Minimization of Frost Formation

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Energy Engineering 2022年第5期119卷 1771-1788页

作者： Felipe Mercês Biglia Raquel da Cunha Ribeiro da Silva Fátima deMoraes Lino Kamal Abdel radi Ismail Thiago Antonini Alves Federal University of Technology-Parana(UTFPR) CuritibaBrazil Federal University of Technology-Parana(UTFPR) GuarapuavaBrazil University of Campinas(UNICAMP) CampinasBrazil Federal University of Technology-Parana(UTFPR) Ponta GrossaBrazil

The frost growth on cold surfaces in evaporators is an undesirable phenomenon which becomes a problem for the thermal efficiency of the refrigeration systems because the ice layer acts as a thermal insulation,drastically reducing the rate of heat transfer in the *** accumulation implies an increase in energy demand and a decrease in the performance of various components involved in the refrigeration process,reducing its efficiency and making it necessary to periodically remove the frost,resulting in expenses for the defrost *** the present work,a numerical-experimental analysis was performed in order to understand the formation process of porous ice in flat plates with different surface treatments and *** understanding is of utmost importance to minimize the formation of porous ice on cold surfaces and improve equipment efficiency and *** this context,a low-cost experimental apparatus was developed,enabling an experimental analysis of the phenomenon under *** environmental conditions evaluated are the temperature of the cold surface,roomtemperature,humidity,and air *** material of the surfaces under study are aluminum,copper,and brass with different surface finishes,designated as smooth,grooved(hydrophilic),and varnished(hydrophobic).The numerical-experimental analysis demonstrates measurements and simulations of the thickness,surface temperature,and growth rate of the porous ice layer as a function of the elapsed *** numerical results were in good agreement with the experimental results,indicating that the varnished surface,with hydrophobic characteristics,presents greater difficulty in providing the ***,the results showed that application of a coating allowed a significant reduction on the frost formation process contributing to the improvement of thermal efficiency and performance of refrigeration systems.

关键词： Frost layer growth frost thickness minimization of frost hydrophobic surface refrigeration systems

Timing of Elective Repeat Cesarean Delivery at 38 Weeks versus 39 Weeks: Rate of Spontaneous Onset of Labor before Planned Cesarean Section and Impact on Maternal Outcome: A Retrospective Cohort Study

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Open Journal of Obstetrics and Gynecology 2023年第3期13卷 550-565页

作者： Amal radi Al Somairi Wafa Abdulaziz Bedaiwi Yaser Abdulkarim Faden King Abdulaziz Medical City Jeddah KSA

Background: The timing of elective repeat cesarean delivery at 38 weeks versus 39 weeks is still a debatable subject, both regarding maternal and neonatal outcomes. In the Saudi context, there is lack of local data to aid decision-making regarding the timing of elective repeat cesarean delivery. Objectives: To estimate the rate of spontaneous onset of labor before the planned gestational age for repeat cesarean section in women who were booked at gestational age of (39 0/7 - 39 6/7) weeks (W39) versus (38 0/7 - 38 6/7) weeks (W38) and to compare the rate of maternal composite outcome between these groups. Design: Retrospective cohort. Setting: This study was conducted at King Abdulaziz Medical City, Jeddah, KSA. Method: Delivery registry books were reviewed to identify all deliveries from 1 January 2014 to 31 December 2016 (3 years). All low-risk pregnant women who had 2 or more cesarean deliveries and who met the inclusion criteria were included. Results: A total of 440 women were included of whom 318 (72.3%) were planned for elective cesarean section at W38 gestational age and 122 women at W39 gestational age. Mothers planned at W39 had higher rate of emergency cesarean deliveries versus those planned at W38 (18.0% versus 10.4%, p = 0.030;RR = 13.06), most frequently due to early onset of contractions (16.4% versus 8.2%, p = 0.012;RR = 12.17) or cervical dilatation (11.6% versus 5.4%, p = 0.024, RR = 16.15). No difference in the incidence of individual or composite maternal complications was noted between the two groups. Mother’s age (OR 0.93, p = 0.018) and schedule date at W39 (OR = 1.94, p = 0.028) were independently associated with spontaneous onset of labor before the scheduled gestational age, while no association was found with parity, previous number of spontaneous vaginal deliveries, number of previous cesarean deliveries or interval from last cesarean delivery. Conclusion: Elective cesarean section scheduled at 39 weeks of gestation or beyond carries a h

关键词： Elective Cesarean Emergency Cesarean Repeat Cesarean Previous Cesarean Spontaneous Onset of Labor Maternal Outcome Neonatal Outcome Timing of Delivery Risk Factors

Evaluation of implanted perforated lacrimal punctal plugs using anterior segment optical coherence tomography

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Eye and Vision 2021年第1期8卷 366-373页

作者： Raafat Mohyeldeen Abdelrahman Abdallah Ahmed Mohamed Kamal Elshafei Heba radi AttaAllah Ophthalmology Department Minia UniversityEl‑MiniaEgypt Ophthalmology Department Minia University HospitalEl‑MiniaEgypt

Purpose:Evaluation of the patency and position of perforated lacrimal punctal plugs implanted for treating punctal stenosis together with quantitative assessment of the precorneal tear film using anterior segment optical coherence tomography(AS-OCT).Methods:In a prospective study,the lower punctum of 54 eyes of 29 patients implanted with perforated punctal plugs were examined using AS-OCT during the early postoperative *** tear meniscus height(TMH)and tear meniscus area(TMA)were ***,the patency of the plug,its position,TMH and TMA were evaluated,and the results were correlated with postoperative *** scale was used for epiphora ***:Using AS-OCT,48(88.9%)plugs were found in proper position while 6(11.1%)were *** lumen of the plugs was completely patent in 47(87%)plugs,partially obstructed in 2(3.7%)plugs and completely occluded in 5(9.2%)*** was a statistically significant postoperative decrease of TMH and TMA(P<0.001)and postoperative epiphora Munk score(P<0.001).Conclusion:AS-OCT is a valuable,reliable,and noninvasive investigative tool that can detect the proper positioning,patency,and contents of the implanted perforated lacrimal punctal plugs in addition to measurement of TMH and TMA.

关键词： AS-OCT Perforated plugs Plugs

Correlation between corneal demarcation line depth in epithelium-off and trans-epithelium accelerated corneal cross linking and keratoconus progression

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International Journal of Ophthalmology(English edition) 2020年第6期13卷 907-912页

作者： Mahmoud Abdel-radi Zeiad Eldaly Hazem Abdelmotaal Reham Abdelrahman Mohamed Sayed Kamel Soliman Department of Ophthalmology Assiut UniversityAssiut 71516Egypt

AIM:To compare corneal demarcation line(DL)depth in both accelerated epithelium-off and trans-epithelium cross linking(CXL)using anterior segment optical coherence tomography(AS-OCT)and its relation to maximum keratometry(Kmax)progression in both ***:A prospective comparative interventional study where patients with mild to moderate keratoconus(KC)were classified into two groups:accelerated epitheliumoff and trans-epithelium CXL based on corneal *** of corneal DL depth was carried out after 3mo by *** readings were evaluated after one year follow up using the Scheimpflug imaging ***:Study included 74 eyes of 44 *** A underwent epithelium-off CXL(41 eyes),while Group B underwent trans-epithelium CXL(33 eyes).At 3mo follow up,mean corneal DL depth in Group A was 219.9±58.4μm while in Group B was 127.2±7.8μm(P0.05).In addition,no significant change in corneal pachymetry was found in both groups(meanchange at 1y:6.4±4.7 and-10.1±2.3μm in Groups A and B respectively).CONCLUSION:Despite a significantly deeper corneal DL depth created by accelerated epithelium-off CXL technique compared to accelerated trans-epithelium CXL,there is no significant impact on keratoconus progression.

关键词： anterior segment optical coherence tomography cross linking demarcation line keratoconus

Interference-Aware Multipath Routing Protocol for QoS Improvement in Event-Driven Wireless Sensor Networks

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Tsinghua Science and Technology 2011年第5期16卷 475-490页

作者： Marjan radi Behnam Dezfouli Kamalrulnizam Abu Bakar Shukor Abd Razak Mohammad Ali Nematbakhsh Faculty of Computer Science and Information Systems Universiti Teknologi Malaysia Faculty of Computer Engineering University of Isfahan

The existing multipath routing protocols for wireless sensor networks demonstrate the efficacy of traffic distribution over multiple paths to fulfill the Quality of Service （QoS） requirements of different applications. However, the performance of these protocols is highly affected by the characteristics of the wireless channel and may be even inferior to the performance of single-path approaches. Specifically, when multiple adjacent paths are being used concurrently, the broadcast nature of wireless channels results in inter-path interference which significantly degrades end-to-end throughput. In this paper, we propose a Low- Interference Energy-efficient Multipath Routing protocol （LIEMRO） to improve the QoS requirements of event-driven applications. In addition, in order to optimize resource utilization over the established paths, LIEMRO employs a quality-based load balancing algorithm to regulate the amount of traffic injected into the paths. The performance gain of LIEMRO compared to the ETX-based single-path routing protocol is 85%, 80%, and 25% in terms of data delivery ratio, end-to-end throughput, and network lifetime, respectively. Furthermore, the end-to-end latency is improved more than 60%.

关键词： LIEMRO QoS load balancing interference multipath routing event-driven

Anodic voltammetric determination of gemifloxacin using screen-printed carbon electrode

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Journal of Pharmaceutical Analysis 2013年第2期3卷 132-136页

作者： Abd-Elgawad radi Amira Khafagy Amira El-shobaky Hatem El-mezayen Department of Chemistry Faculty of ScienceDumyat University Department of Chemistry Faculty of ScienceHelwan University

The electrochemical oxidation behavior and voltammetric assay of gemifloxacin were investigated using differential-pulse and cyclic voltammetry on a screen-printed carbon *** effects of pH,scan rates,and concentration of the drug on the anodic peak current were *** of gemifloxacin in Tris-HCl buffer（pH 7.0） exhibited a well-defined single oxidation peak.A differential-pulse voltammetric procedure for the quantitation of gemifloxacin has been developed and suitably validated with respect to linearity,limits of detection and quantification,accuracy,precision,specificity,and *** calibration was linear from 0.5 to 10.0 μM,and the limits of detection and quantification were 0.15 and 5.0 μ*** ranging from 96.26% to 103.64% were *** method was successfully applied to the determination of gemifloxacin in pharmaceutical tablets without any *** present in the tablets did not interfere in the assay.

关键词： Screen-printed carbon electrode Voltammetry Gemifloxacin Pharmaceutical analysis

Thermal-Mechanical Coupled FE Analysis for Rotary Shaft Seals

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Modern Mechanical Engineering 2018年第1期8卷 95-110页

作者： Gyorgy Szabó Károly Váradi Department of Machine and Product Design Budapest University of Technology and EconomicsBudapestHungary

The aim of this paper is to model the steady-state condition of a rotary shaft seal (RSS) system. For this, an iterative thermal-mechanical algorithm was developed based on incremental finite element analyzes. The behavior of the seal’s rubber material was taken into account by a large-strain viscoelastic, so called generalized Maxwell model, based on Dynamic Mechanical Thermal Analyses (DMTA) and tensile measurements. The pre-loaded garter spring was modelled with a bilinear material model and the shaft was assumed to be linear elastic. The density, coefficient of thermal expansion and the thermal conductance of the materials were taken into consideration during simulation. The friction between the rotary shaft seal and the shaft was simplified and modelled as a constant parameter. The iterative algorithm was evaluated at two different times, right after assembly and 1 h after assembly, so that rubber material’s stress relaxation effects are also incorporated. The results show good correlation with the literature data, which state that the permissible temperature for NBR70 (nitrile butadiene rubber) material contacting with ~80 mm shaft diameter, rotating at 2600/min is 100°C. The results show 107°C and 104°C for the two iterations. The effect of friction induced temperature, changes the width of the contact area between the seal and the shaft, and significantly reduces the contact pressure.

关键词： Coupled FE Analysis Thermal-Mechanical Coupling Rotary Shaft Seals NBR Rubber Viscoelasticity

The archaeogenomic validation of Saint Ladislaus'relic provides insights into theárpád dynasty's genealogy

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Journal of Genetics and Genomics 2023年第1期50卷 58-61页

作者： Gergely I.B.Varga Lilla Alida Kristóf Kitti Maár Luca Kis Oszkár Schütz Orsolya Váradi Bence Kovács Alexandra Gînguță Balázs Tihanyi Péter L.Nagy Zoltán Maróti Emil Nyerki Tibor Török Endre Neparáczki Department of Archaeogenetics Institute of Hungarian ResearchH-1014 BudapestHungary Doctoral School of History University of SzegedSzegedHungary Department of Genetics University of SzegedH-6726 SzegedHungary Department of Biological Anthropology University of SzegedH-6726 SzegedHungary Department of Molecular Biology and Biotechnology Faculty of Biology and GeologyBabes-Bolyai University400006 Cluj-NapocaRomania Praxis Genomics LLC AtlantaUSA Department of Pediatrics and Pediatric Health Center University of SzegedH-6725 SzegedHungary

The house of Arp ad ruled Hungary for more than four centuries,establishing dynastical relationships with numerous European nobleand ruling houses,and giving many Catholic saints and blesseds to the Catholic *** were one of the significant dynasties of Medieval Europe(Krist o and Makk,1996).The knight-king Saint Ladislaus I(c.1040-1095,reign:1077-1095)is one of the most outstanding kings of this *** addition to the hand relic(the Holy Right)of King Saint Stephanus I(c.975-1038,reign:1000/1001-1038),the skull relic in the Saint Ladislaus’Herma(Fig.1A-1C)preserved in the Cathedral of Gy or,is one of the most important relics for Hungarians(Klaniczai,2000).

关键词： relic provides insights into the The archaeogenomic validation of Saint Ladislaus d dynasty’s genealogy