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LES of rotating film-cooling performance in a 1-1/2 turbine stage

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Propulsion and Power Research 2019年第2期8卷 85-107页

作者： Nabeel al-Zurfi Adel nasser Mechanical Engineering Department Faculty of EngineeringUniversity of KufaNajafIraq School of Mechanical Aerospace and Civil EngineeringThe University of ManchesterManchesterM139PLUK

The large eddy simulation method was employed to investigate the film-cooling performance in a low-speed rotor blade of a 1-1/2 turbine *** rotor blade height and axial chord length were 99 mm and 124.3 mm,*** rows of film holes were placed on the rotor blade surface,one each on the pressure and suction *** row had three cylindrical film holes with a diameter of 4 mm and a tangential injection angle of 28°on the pressure side and 361 on the suction *** Reynolds number was fixed at Re=1.92×10^(5)and the coolant-to-mainstream density ratio(DR)was about *** were carried out for three different rotating speeds of 1800,2100,and 2400 rpm with the blowing ratio(BR)varying from 0.3 to *** commercial CFD code STAR-CCM+was used to run the simulations using the WalE subgrid-scale model for modelling the *** results show that on the pressure side,the film coverage and filmcooling effectiveness decrease with increasing rotation number(Ro)and increase with increasing blowing ratio(BR).A higher Ro and lower BR result in a stronger film *** film injection with higher BR produces better film *** film deflects centrifugally where the deflection becomes greater with increasing *** the suction side,the film coverage and film-cooling effectiveness increase with increasing either Ro or BR and a centripetal deflection of the film is *** deflection of the film path could be amplified by either increasing the Ro at a constant BR or decreasing the BR at a constant *** the rotation weakens the film deflection towards the hub on the suction ***,it was found that both rotation number and blowing ratio play significant roles in determining the film-cooling effectiveness distributions of the rotor blade surface.

关键词： Rotor blade Large eddy simulation Film-cooling effectiveness Turbulence Rotation Subgrid-scale

A Taxonomy of Exact Methods for Partial Max-SAT

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Journal of Computer Science & Technology 2013年第2期28卷 232-246页

作者： Mohamed El Bachir Menai Tasniem nasser al-Yahya Department of Computer Science College of Computer and Information Sciences King Saud University

Partial Maximum Boolean Satisfiability （Partial Max-SAT or PMSAT） is an optimization variant of Boolean satisfiability （SAT） problem, in which a variable assignment is required to satisfy all hard clauses and a maximum number of soft clauses in a Boolean formula. PMSAT is considered as an interesting encoding domain to many reaHife problems for which a solution is acceptable even if some constraints are violated. Amongst the problems that can be formulated as such are planning and scheduling. New insights into the study of PMSAT problem have been gained since the introduction of the Max-SAT evaluations in 2006. Indeed, several PMSAT exact solvers have been developed based mainly on the Davis- Putnam-Logemann-Loveland （DPLL） procedure and Branch and Bound （B^B） algorithms. In this paper, we investigate and analyze a number of exact methods for PMSAT. We propose a taxonomy of the main exact methods within a general framework that integrates their various techniques into a unified perspective. We show its effectiveness by using it to classify PMSAT exact solvers which participated in the 2007~2011 Max-SAT evaluations, emphasizing on the most promising research directions.

关键词： Partial Max-SAT Davis-Putnam-Logenmann-Loveland branch and bound unsatisfiability pseudo-Boolean optimization

Effects of Rate and Source Organo-Mineral Material on Forage Yield and Nutritive Value of Barley-Pea Mixed under Arid Conditions

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Phyton-International Journal of Experimental Botany 2022年第7期91卷 1483-1493页

作者： Walid Soufan nasser A.al-Suhaibani Plant Production Department College of Food and Agriculture SciencesKing Saud UniversityRiyadh11451Saudi Arabia

Cereal-legume intercropping plays a vital role in the subsistence food production system that prevails in the arid *** not only provides profitable crop productivity for agricultural communities but also plays an important role in improving soil ***,the present research was conducted to assess the effect of the organic and mineral fertilizers on the forage yield and nutritional value in barley-pea intercropping *** results revealed that the quality of forage grass is significantly influenced by both organic and inorganic ***,organic fertilizer application has significantly influenced the dry matter(DM),crude ash(CA),crude protein(CP),neutral detergent fiber(NDF),and acid detergent fiber(ADF).Among the treatments,organic fertilizer added at rate of 35 m^(−3) ha^(−1) produced the maximum fresh and dry matter in barley and *** addition,the same level of organic fertilizer also improved silage composition by significantly increasing the protein and fiber content and showed highest the *** on overall results,it is concluded that organic fertilizer treatment(35 m^(−3) ha^(−1))has the potential as an effective strategy to improve the productivity and nutritional quality of the barley-pea intercropping system in arid *** results revealed that organic fertilizer can be utilized in sustainable agricultural as a source of nutrients for numerous various crops under arid conditions.

关键词： Organic fertilizer barley pea yield quality hay silage

How elevation and soil properties affect plant distribution patterns and species diversity in the Mediterranean mountain ecosystem of al-Jabal al- Akhdar, Libya

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Journal of Mountain Science 2024年第11期21卷 3683-3701页

作者： ABD EL-GHANI Monier al BORKI Abd El-nasser Department of Botany and Microbiology Faculty of ScienceCairo UniversityGiza 12613Egypt Department of Biology Faculty of EducationUniversity of BenghaziBenghaziLibya

The objectives of this study were to assess distribution patterns of plant species richness,plant diversity and vegetation structure in relation to environmental factors along elevation gradient in al-Jabal al-Akhdar,*** each species,its growth form,chorological affinities,degree of occurrence,endemism status and originality were provided.A total of 534 taxa were generated from 70 families of the flowering plants,and 3 of the non-flowering plants were *** native flora of the study area was counted for 80.2%of the total indigenous taxa(465).The hump-shaped pattern of plant species richness was obtained,with the highest species richness at the mid-elevations,and both ends of the gradient have the *** annuals(300 species,56.2%)and non-succulent perennial herbs(165 species,30.9%)were the most dominant growth forms of the total species *** the elevation gradient,Asteraceae,Fabaceae,Poaceae,Lamiaceae and Apiaceae were the dominant families with the highest numbers of *** investigation recorded 31 endemic taxa,comprising 25 dicots and 6 monocots,primarily of Mediterranean origin,with most belonging to the Asteraceae and Lamiaceae *** chorotype was the dominant,whether pure(mono-),or combined with one(bi-and pluri-regional)or more(pluri-regional).Application of cluster analysis on the vegetation data yielded four cluster groups;each was linked to an elevation *** emphasized the importance of establishing conservation strategies to minimize human disturbance and safeguard relic habitats of Juniperus phoenicea *** its southern distribution limits in Africa,underlining the proactive management required for species *** application of Redundancy Analysis revealed that Shannon diversity index(H'),pH and Fe were the determinant soil factor in the mid-elevation levels(L2 and L3)whereas altitude,fine sand,HCO3,OM,and soil contents of Na,SO4 and Cl for the extreme levels(L1 and L4).

关键词： altitudinal gradient Distribution patterns Floristic diversity Growth forms Libya Soil structure Vegetation analysis

Oncogenic BRAF^(V600E) induces microglial proliferation through extracellular signal-regulated kinase and neuronal death through c-Jun N-terminal kinase

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Neural Regeneration Research 2023年第7期18卷 1613-1622页

作者： Qing Ye Pranay Srivastava nasser al-Kuwari Xiqun Chen Department of Neurology Massachusetts General HospitalHarvard Medical SchoolCharlestownMAUSA Department of Neurology Longhua HospitalShanghai University of Traditional Chinese MedicineShanghaiChina aligning Science Across Parkinson’s(ASAP)Collaborative Research Network Chevy ChaseMDUSA

Activating V600E in v-Raf murine sarcoma viral oncogene homolog B(BRAF)is a common driver mutation in cancers of multiple tissue origins,including melanoma and ***^(V600E) has also been implicated in *** present study aims to characterize BRAF^(V600E) during cell death and proliferation of three major cell types of the central nervous system:neurons,astrocytes,and *** primary cultures(primary cortical mixed culture)and cell lines of glial cells(BV2)and neurons(SH-SY5Y)were ***^(V600E) and BRAF^(WT) expression was mediated by lentivirus or *** of downstream effectors(extracellular signal-regulated kinase 1/2 and JNK1/2)were achieved by *** astrocytes and microglia,BRAF^(V600E) induces cell proliferation,and the proliferative effect in microglia is mediated by activated extracellular signal-regulated kinase,but not c-Jun N-terminal *** medium from BRAF^(V600E)-expressing microglia induced neuronal *** neuronal cells,BRAF^(V600E) directly induces neuronal death,through c-Jun N-terminal kinase but not extracellular signal-regulated *** further show that BRAF-related genes are enriched in pathways in patients with Parkinson’s *** study identifies distinct consequences mediated by distinct downstream effectors in dividing glial cells and in neurons following the same BRAF mutational activation and a causal link between BRAF-activated microglia and neuronal cell death that does not require physical *** provides insight into a possibly important role of BRAF in neurodegeneration as a result of either dysregulated BRAF in neurons or its impact on glial cells.

关键词： astrocytes cell death cell proliferation inflammation microglia mutation neurons v-Raf murine sarcoma viral oncogene homolog B(BRAF)

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

In vitro Evaluation of Seed Germination in Twelve alfalfa Cultivars under Salt Stress

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Phyton-International Journal of Experimental Botany 2023年第1期92卷 111-120页

作者： Walid Soufan Yaser Hassan Dewir nasser A.al-Suhaibani Plant Production Department College of Food and Agriculture SciencesKing Saud UniversityRiyadh11451Saudi Arabia

alfalfa(Medicago sativa L.),when exposed to abiotic stress such as salinity,suffers significant losses in yield and *** present study evaluated the salinity tolerance of 12 alfalfa cultivars in vitro using five concentrations of sodium chloride(NaCl),ranging from 0 to 250 mmol L^(−1).The results obtained in the current study revealed that the Saudi cultivars,Kasimi and Hassawi,and the German cultivar(Berlin)had the highest salinity tolerance in terms of germination percentage(GP),corrected germination rate index(CGRI),days to reach 50%germination(GT_(50)),and ability to form cotyledonary and true *** mmol L^(−1) NaCl,the Saudi cultivar Kasimi cultivar showed GP,CGRI,and GT_(50) of 55.20%,123.15,and 3.77 days,***,the German cultivar(Berlin)showed GP,CGRI,and GT_(50) of 50.06%,86.61,and 5.17 days,*** findings might reveal a pivotal aspect in salt tolerance in *** results will help to select salt-tolerant alfalfa cultivars that could thrive in arid and semi-arid areas with salinity problems.

关键词： Medicago sativa L. salinity germination screening salt tolerance

Histopathological alterations in the liver and intestine of Nile tilapia Oreochromis niloticus exposed to long-term sublethal concentrations of cadmium chloride

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Chinese Journal of Oceanology and Limnology 2015年第4期33卷 846-852页

作者： YOUNIS Elsayed ABDEL-WARITH Abdel-Wahab al-ASGAH nasser EBAID Hossam Department of Zoology College of Science King Saud University Department of Animal Production Faculty of Agriculture Al-Azhar University Department of Zoology College of Science El-Minia University

Fingerlings of Nile tilapia Oreochromis niloticus were exposed to 1.68, 3.36, and 5.04 mg/L cadmium(as CdCl2), which represent 10%, 20%, and 30% of their previously determined 96-h LC5 0. After exposure for 20 days, sections of the liver and intestine of treated fish were examined histologically. Histopathological changes varied from slight to severe structural modification, depending on the exposure concentration. The hepatic tissues of fish exposed to 10% LC 50 showed markedly increased vacuolation of the hepatocytes and coarse granulation of their cytoplasm. Abundant erythrocytic infiltration among the hepatocytes was observed in fish exposed to 20% LC5 0. In the intestinal tissues of fish exposed to all doses, goblet cells proliferated and were greatly increased in size, the longitudinal muscularis mucosa was disturbed and, in the crypts of the sub-mucosal layer, apoptosis increased, indicated by large numbers of degenerated nuclei. Large numbers of inflammatory cells and dilated blood vessels were observed in the intestine of the group treated with 30% LC5 0.

关键词： fish tilapia pollutant cadmium liver intestine

A numerical study of anti-vortex film-cooling holes designs in a 1-1/2 turbine stage using LES

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Propulsion and Power Research 2019年第4期8卷 275-299页

作者： Nabeel al-Zurfi ali Turan Adel nasser Ahmed alhusseny Department of Mechanical Engineering Faculty of EngineeringUniversity of KufaNajafIraq Visiting Researcher Department of MechanicalAerospace and Civil EngineeringSchool of EngineeringFaculty of Science and EngineeringThe University of ManchesterManchesterM139PLUK Department of Mechanical Aerospace and Civil EngineeringSchool of EngineeringFaculty of Science and EngineeringThe University of ManchesterManchesterM139PLUK

The primary focus of the present study is to investigate the impact of anti-vortex holes design on the film-cooling performance in a film-cooled rotor blade model using the large eddy simulation method(LES).One row of the film holes was positioned on the pressure surface of the rotor *** row had three cylindrical holes(the main hole in the present study)with a diameter(D)of 4 mm and a tangential injection angle of 28 *** main hole supplemented with the addition of two symmetrical side holes(anti-vortex holes),which branch out from the same main *** positions for the anti-vortex side holes were considered;namely:upstream to the outlet of the main hole;in line with the main hole;and downstream of the main *** Reynolds number was fixed at Re Z 1.92105 and the speed of the rotor blade was taken to be 1800 *** blowing ratio varied from 1.0 to 5.0 and the density ratio of coolant to mainstream was *** to the base hole,the film cooling performance of the all anti-vortex cases showed obvious improvement at all blowing *** middle stream side holes and downstream side holes each demonstrated good film cooling performance at all blowing ratios,while the upstream side holes perform well only at a lower blowing *** presence of side holes can restrain the CRVP(counter rotating vortex pairs)intensity of the main hole and reduce the coolant lift-off,improving the film coverage and film cooling *** downstream side holes can perform better in reducing the CRVP intensity.

关键词： Rotor blade Large eddy simulation Film-cooling effectiveness Turbulence Rotation Anti-vortex hole