检索结果-南通市图书馆

Enhancing asphaltene precipitation modeling by cubic-PR solid model using thermodynamic correlations and averaging techniques

在线全文

学校读者我要写书评

暂无评论

Petroleum Science 2020年第1期17卷 232-241页

作者： Aktham E.Shoukry Ahmed h.el-Banbi helmy Sayyouh Petroleum Engineering University of WyomingLaramieWYUSA Petroleum Department Faculty of EngineeringCairo UniversityGizaEgypt Petroleum Engineering American University in Cairo(AUC)GizaEgypt

Cubic equation-of-state solid models are one of the most widely used models to predict asphaltene precipitation *** parameters are needed to model precipitation under different pressures and temperatures and are usually obtained through tuning with multi asphaltene onset *** the purpose of enhancing the cubic Peng–Robinson solid model and reducing its dependency on asphaltene experiments,this paper tests the use of aromatics and waxes correlations to obtain these thermodynamic *** addition,weighted averages between both correlations are *** averaging is based on reported saturates,aromatics,resins,asphaltene(SARA)fractions,and wax *** the methods are tested on four oil samples,with previously published data,covering precipitation and onset *** proposed wax-asphaltene average showed the best match with experimental data,followed by a SARA-weighted *** new addition enhances the model predictability and agrees with the general molecular structure of asphaltene molecules.

关键词： Asphaltene precipitation Asphaltene onset pressure Asphaltene precipitation modeling Asphaltene thermodynamics Cubic equation of state

Fictitious soil pile model for dynamic analysis of pipe piles under high-strain conditions

在线全文

学校读者我要写书评

暂无评论

Frontiers of Structural and Civil Engineering 2023年第6期17卷 915-934页

作者： Yuan TU M.h.el NAGGAR Kuihua WANG Wenbing WU Juntao WU School of Civil Engineering and Architecture Zhejiang Sci-Tech UniversityHangzhou310018China MOE Key Laboratory of Soft Soils and Geoenvironmental Engineering Zhejiang UniversityHangzhou310058China Geotechnical Research Centre Department of Civil and Environmental EngineeringThe University of Western OntarioLondonONN6A 5B9Canada Engineering Research Center of Rock-Soil Drilling Excavation and Protection Ministry of EducationChina University of GeosciencesWuhan430074China

A fictitious soil pile(FSP)model is developed to simulate the behavior of pipe piles with soil plugs undergoing high-strain dynamic impact *** developed model simulates the base soil with a fictitious hollow pile fully filled with a soil plug extending at a cone angle from the pile toe to the *** friction on the outside and inside of the pile walls is distinguished using different shaft models,and the propagation of stress waves in the base soil and soil plug is *** motions of the pile—soil system are solved by discretizing them into spring-mass model based on the finite difference *** of the predictions of the proposed model and conventional numerical models,as well as measurements for pipe piles in field tests subjected to impact loading,validate the accuracy of the proposed model.A parametric analysis is conducted to illustrate the influence of the model parameters on the pile dynamic ***,the effective length of the FSP is proposed to approximate the affected soil zone below the pipe pile toe,and some guidance is provided for the selection of the model parameters.

关键词： fictitious soil pile soil plug pipe piles high-strain dynamic analysis one-dimensional wave theory pile dynamics

hepG2 cells support viral replication and gene expression of hepatitis C virus genotype 4 in vitro

在线全文

学校读者我要写书评

暂无评论

World Journal of Gastroenterology 2006年第30期12卷 4836-4842页

作者： Mostafa K el-Awady Ashraf A Tabll Yasmine S el-Abd Mahmoud M Bahgat hussein A Shoeb Samar S Youssef Noha G Bader el Din el-Rashdy M Redwan Maha el-Demellawy Moataza h Omran Wael T el-Garf Said A Goueli Department of Biomedical Technology National Research Center Tahrir Street PO 12622 Dokki Cairo Egypt Department of Medicinal Chemistry Na- tional Research Center Tahrir Street PO 12622 Dokki Cairo Egypt Department of Microbiology and Immunology Faculty of Pharmacy Cairo University Cairo Egypt Genetic Engineering and Biotechnology Research Institute New Borg El-Arab City Alexandria Egypt Department of Pathology School of Medicine University of Wisconsin Madison WI United States

AIM： TO establish a cell culture system with longterm replication of hepatitis C virus （hCV） genome and expression of viral antigens in vitro. METhODS： hepG2 cell line was tested for its susceptibility to hCV by incubation with a serum from a patient with chronic hepatitis C. Cells and supernatant were harvested at various time points during the culture. Culture supernatant was tested for its ability to infect na＇ive cells. The presence of minus （antisense） RNA strand, and the detection of core and E1 antigens in cells were examined by RT-PCR and immunological techniques （flow cytometry and Western blot） respectively. RESULTS： The intracellular hCV RNA was first detected on d 3 after infection and then could be consistently detected in both cells and supernatant over a period of at least three months. The fresh cells could be infected with supernatant from cultured infected cells. Flow cytometric analysis showed surface and intracellular hCV antigen expression using in house made polyclonal antibodies （anti-core, and anti-E1）. Western blot analysis showed the expression of a cluster of immunogenic peptides at molecular weights extended between 31 and 45 kDa in an one month old culture of infected cells whereas this cluster was undetectable in uninfected hepG2 cells. CONCLUSION： hepG2 cell line is not only susceptible to hCV infection but also supports its replication in vitro. Expression of hCV structural proteins can be detected in infected hepG2 cells. These cells are also capable of shedding viral particles into culture media which in turn become infectious to uninfected cells.

关键词： hepatitis C virus In vitro propagation Genomic replication Gene expression hepG2 cells

Prenylated flavonoids from Tephrosia apollinea

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2009年第12期20卷 1465-1468页

作者： Ali K.Khalafallah Suleiman A.Suleiman Afifi h.Yousef Nadia A.A.el-kanzi Abou el-hamd h.Mohamed Department of Chemistry Faculty of ScienceSouth Valley UniversityAswanEgypt

In continuation of our chemical investigation on some medicinal plants of the genus Tephrosia, re-investigation of the methylenechloride/methanol （1：1） extract of the air-dried aerial part of Tephrosia apollinea afforded a new prenylated flavonoid 1, in addition to an aromatic ester, a sesquiterpene, a lignan and several known prenylated flavonoids. The structures were established by （^1h NMR, ^13C NMR, DEPT, ^1h-^1h COSY, hMQC, hMBC, NOESY and hRMS）. Relative configurations of 9 and 10 were confirmed by X-ray analysis.

关键词： Tephrosia apollinea Leguminosae Prenylated flavonoids

Detection of virulent strains of helicobacter pylori and its relation to symptoms and signs in children

在线全文

学校读者我要写书评

暂无评论

Asian Pacific Journal of Tropical Medicine 2010年第1期3卷 59-62页

作者： Fayed S Abd el Dayem S hussein h Sherief M el-Naghi S Pediatric Department Al Azhar University Pediatric Department National Research Centre Microbiology Department Al Azhar University Pediatric Department National Hepatology and Tropical Medicine Research

Objective:To detect the prevalence of helicobacter polori(***) in a group of pediatric patients complaining of gastrointestinal disorders,and to identify the virulent strains of h. pylori and its relation to peptic ***:The study included 60 patients(41 males and 19 females),aged from 6 months to 14 years,with complaining of different gastrointestinal *** IgG antibodies were *** examination of the oesophagus, stomach and duodenum was done in all patients using a fibreoptic *** addition, gastric antral biopsies were taken for diagnosis of *** infection in the following test: rapid urease test,histopathologic examination and *** cytotoxin assay of virulent strains was *** infection was diagnosed if 3 or more tests for diagnosis were found to be ***:33 out of 60 patients(55%) was positive.12(20%) patients had positive toxin producing strains(virulent strains).Virulent strain had a significantly closer relationship with recurrent abdominal pain,while no difference was found in other symptoms. Age of patients showed a highly significant positive correlation with virulent *** strain. histopathological finding revealed that oesophagitis was significandy common in patients with negative *** and histopathological findings revealed that virulent strain had a significandy higher gastritis and oesophagitis ***:Infection by virulent strains of *** in children is not uncommon:It is associated with endoscopic and histopathologic *** cases infected with virulent strain showed positive results by using rapid urease test,culture and IgG antibodies.

关键词： helicobacter pylori IgG antibody Pediatric Gastrointestinal disorder

Continuous-cyclic variations in the b-value of the earthquake frequency-magnitude distribution

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Earthquake Science 2013年第5期26卷 301-320页

作者： Z.h.el-Isa Geology Department University of Jordan

Seismicity of the Earth （M ≥ 4.5） was compiled from NEIC, IRIS and ISC catalogues and used to compute b-value based on various time windows. It is found that continuous cyclic b-variations occur on both long and short time scales, the latter being of much higher value and sometimes in excess of 0.7 of the absolute b-value. These variations occur not only yearly or monthly, but also daily. Before the occurrence of large earthquakes, b-values start increasing with variable gradients that are affected by foreshocks. In some cases, the gradient is reduced to zero or to a negative value a few days before the earthquake occurrence. In general, calculated b-values attain maxima 1 day before large earthquakes and minima soon after their occurrence. Both linear regression and maximum likelihood methods give correlatable, but variable results. It is found that an expanding time window technique from a fixed starting point is more effective in the study of b-variations. The calculated b-variations for the whole Earth, its hemispheres, quadrants and the epicentral regions of some large earthquakes are of both local and regional character, which may indicate that in such cases, the geodynamic processes acting within a certain region have a much regional effect within the Earth. The b-variations have long been known to vary with a number of local and regional factors including tectonic stresses. The results reported here indicate that geotectonic stress remains the most significant factor that controls b-variations. It is found that for earthquakes with Mw ≥ 7, an increase of about 0.20 in the b-value implies a stress increase that will result in an earthquake with a magnitude one unit higher.

关键词： Earthquake frequency-magnitude b-value Temporal b-variation Spatial b-variation

A Proposed Biometric Authentication Model to Improve Cloud Systems Security

在线全文

学校读者我要写书评

暂无评论

Computer Systems Science & Engineering 2022年第11期43卷 573-589页

作者： hosam el-el-Sofany King Khalid University AbhaKingdom of Saudi Arabia Cairo higher Institute for Engineering Computer Science and ManagementCairoEgypt

Most user authentication mechanisms of cloud systems depend on the credentials approach in which a user submits his/her identity through a username and ***,this approach has many security problems because personal data can be stolen or recognized by *** paper aims to present a cloud-based biometric authentication model(CBioAM)for improving and securing cloud *** research study presents the verification and identification processes of the proposed cloud-based biometric authentication system(CBioAS),where the biometric samples of users are saved in database servers and the authentication process is implemented without loss of the users’*** paper presents the performance evaluation of the proposed model in terms of three main characteristics including accuracy,sensitivity,and *** research study introduces a novel algorithm called“Bio_Authen_as_a_Service”for implementing and evaluating the proposed *** proposed system performs the biometric authentication process securely and preserves the privacy of user *** experimental result was highly promising for securing cloud services using the proposed *** experiments showed encouraging results with a performance average of 93.94%,an accuracy average of 96.15%,a sensitivity average of 87.69%,and a specificity average of 97.99%.

关键词： Cloud computing cloud security biometrics technologies biometric authentication

Task Scheduling Optimization in Cloud Computing by Rao Algorithm

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Computers, Materials & Continua 2022年第9期72卷 4339-4356页

作者： A.Younes M.Khelnahary Monagi h.Alkinani hamdy h.el-Sayed Faculty of Computers and Information Department of Computer ScienceSohag UniversitySohag82524Egypt Department of Computer Science and Artificial Intelligence College of Computer Science and EngineeringUniversity of JeddahJeddah21959Saudi Arabia

Cloud computing is currently dominated within the space of highperformance distributed computing and it provides resource polling and ondemand services through the ***,task scheduling problem becomes a very important analysis space within the field of a cloud computing environment as a result of user’s services demand modification *** main purpose of task scheduling is to assign tasks to available processors to produce minimum schedule length without violating precedence *** heterogeneous multiprocessor systems,task assignments and schedules have a significant impact on system *** the heuristic-based task scheduling algorithm,the different processes will lead to a different task execution time(makespan)on a heterogeneous computing ***,a good scheduling algorithm should be able to set precedence efficiently for every subtask depending on the resources required to reduce(makespan).In this paper,we propose a new efficient task scheduling algorithm in cloud computing systems based on RAO algorithm to solve an important task and schedule a heterogeneous multiple processing *** basic idea of this process is to exploit the advantages of heuristic-based algorithms to reduce space search and time to get the best *** evaluate our algorithm’s performance by applying it to three examples with a different number of tasks and *** experimental results show that the proposed approach significantly succeeded in finding the optimal solutions than others in terms of the time of task implementation.

关键词： heterogeneous processors RAO algorithm heuristic algorithms task scheduling multiprocessing cloud computing

Dust Acoustic Solitary Waves in Saturn F-ring's Region

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2011年第1期55卷 143-150页

作者： E.K.el-Shewy M.I.Abo el Maaty h.G.Abdelwahed M.A.elmessary Theoretical Physics Group Faculty of ScienceMansoura University Mathematics and Physics Department Faculty of Engineering Mansoura University

Effect of hot and cold dust charge on the propagation of dust-acoustic waves （DAWs） in unmagnetized plasma having electrons, singly charged ions, hot and cold dust grains has been investigated. The reductive perturbation method is employed to reduce the basic set of fluid equations to the Kortewege-de Vries （KdV） equation. At the critical hot dusty plasma density Nho, the KdV equation is not appropriate for describing the system. hence, a set of stretched coordinates is considered to derive the modified KdV equation. It is found that the presence of hot and cold dust charge grains not only significantly modifies the basic properties of solitary structure, but also changes the polarity of the solitary profiles. In the vicinity of the critical hot dusty plasma density Nho, neither KdV nor mKdV equation is appropriate for describing the DAWs. Therefore, a further modified KdV （fmKdV） equation is derived, which admits both soliton and double layer solutions.

关键词： dust-acoustic waves hot and cold dust charge double layer solutions