Two types of cyanobacteria of the genus Arthrospira（commonly known as Spirulina） were tested for biosorption of cerium（III） ions from aqueous solutions. An endemic type（ES） found in the northern Negev desert, Is...Two types of cyanobacteria of the genus Arthrospira（commonly known as Spirulina） were tested for biosorption of cerium（III） ions from aqueous solutions. An endemic type（ES） found in the northern Negev desert, Israel, and a commercial powder（CS） were used in this study. Biosorption was evaluated as a function of p H, contact time, initial metal concentration, number of sorption-desorption cycles, and salt concentration. The optimum p H range for biosorption was found to be 5.0–5.5. The kinetic characteristics of both Spirulina types were found to be highly compatible with a pseudo-second order kinetic model. The adsorption isotherms of both types were found to be well-suited to Langmuir and Freundlich adsorption isotherms. Maximum biosorption uptakes, according to the Langmuir model, were 18.1 and 38.2 mg/g, for ES and CS, respectively. Sodium chloride concentrations of up to 5 g/L had a minor effect on cerium biosorption. Desorption efficiency was found to be greater than 97% with 0.1 mol/L HNO_3 after three sorption-desorption cycles, without significant loss in the biosorption capacity. The results indicated the feasibility of cerium recovery from industrial wastes using Spirulina biomass.展开更多
Doped and undoped TiCh nanoparticles were prepared by Stober method and thermally treated at 600 ℃.The effect of Nd^（3＋） ion on the structure and micro structure of anatase-phase TiCh nanocrystals was studied by R...Doped and undoped TiCh nanoparticles were prepared by Stober method and thermally treated at 600 ℃.The effect of Nd^（3＋） ion on the structure and micro structure of anatase-phase TiCh nanocrystals was studied by Rietveld refinement method using X-ray powder diffraction data.Bond lengths,bond angles,and edges distances were analyzed.The phase formation was confirmed by high-resolution transmission electron microscopy.The adjustment of Ti-0 bond length induced by the addition of Nd^（3＋） ions,reduced the octahedral distortion and altered the octahedral array in the anatase-phase TiCh nanocrystal.The changes of structure and microstructure were mainly observed for TiCh nanoparticles doped with 0.1 at.%of Nd^（3＋） ions and attributed to the cationic substitution of Ti^（4＋） ions which promoted changes in the density of states and gap band of TiCh.The dopant insertion resulted in a better structural stability of the nanocrystals that enhanced their charge transference and photocatalytic efficiency.展开更多
This paper studies the process of mutual neutralization of Si^＋ and H^- ions in slow collisions within the multichannel Landau-Zener model. All important ionic-covalent couplings in this collision system are included...This paper studies the process of mutual neutralization of Si^＋ and H^- ions in slow collisions within the multichannel Landau-Zener model. All important ionic-covalent couplings in this collision system are included in the collision dynamics. The cross sections for population of specific final states of product Si atom are calculated in the CM energy range 0.05 e∨/u-5 ke∨/u. Both singlet and triplet states are considered. At collision energies below -10 e∨/u, the most populated singlet state is Si（3p4p, ^1S0）, while for energies above -150e∨/u it is the Si（3p, 4p, ^1P1） state. In the case of triplet states, the mixed 3p4p（^3S1 ＋^3P0） states are the most populated in the entire collision energy range investigated. The total cross section exhibits a broad maximum around 200 300e∨/u and for ECM ≤ 10e∨/u it monotonically increases with decreasing the collision energy, reaching a value of 8 × 10^-13 cm^2 at ECM = 0.05 e∨/u. The ion-pair formation process in Si（3p^2 ^3PJ）＋H（1s） collisions has also been considered and its cross section in the considered energy range is very small （smaller than 10^-20 cm^2 in the energy region below 1 ke∨/u）.展开更多
In this paper we present a comparative study between PYTHIA, EPOS, QGSJET, and SIBYLL generators. The global event observables considered are the charged energy flow, charged particle distributions, charged hadron pro...In this paper we present a comparative study between PYTHIA, EPOS, QGSJET, and SIBYLL generators. The global event observables considered are the charged energy flow, charged particle distributions, charged hadron production ratios and V^0 ratios. The study is performed in the LHCb and TOTEM fiducial phase spaces on minimum bias simulated data samples for pp collisions at = 7 TeV , using the reference measurements from these experiments. In the majority of cases, the measurements are within a band defined by the most extreme predictions. The observed differences between the predictions and the measurements seem to be, in most part, caused by extrapolation from the central pseudorapidity region (|η| 2.5), in which the generators were mainly tuned.展开更多
Recovery of heat energy from internal combustion engine exhaust will achieve significant road transportation CO2 reduction. Turbocharging and turbogenerating are most commonly used technologies to recover engine exhau...Recovery of heat energy from internal combustion engine exhaust will achieve significant road transportation CO2 reduction. Turbocharging and turbogenerating are most commonly used technologies to recover engine exhaust heat energy.Engine exhaust pulse flow can significantly affect the turbine performance of turbocharging and turbogenerating systems,and it is necessary to consider the pulse flow effects in turbine design and performance analysis.An investigation was carried out by numerical simulation on the mixed flow turbine pulse flow performance and flow fields.Results showed that the variations of the turbine efficiency and flowfiled under pulsating flow conditions demonstrate significant unsteady effects.The effect of blade leading edge sweep on turbine pulse flow performance was studied.It is shown that increasing of the leading edge sweep angle can improve the turbine average instantaneous efficiency by about 2 percent under pulsating flow conditions.展开更多
The objective of the integrated approach is to minimize the cost and duration of the development of the final flow sheet by optimal allocation of the resources to various steps of the development. In the integrated ap...The objective of the integrated approach is to minimize the cost and duration of the development of the final flow sheet by optimal allocation of the resources to various steps of the development. In the integrated approach, the development of a solvent extraction （SX） flow sheet is done in the following order： 1） Definition of the process： composition of the feed, specification of the product, minimum yield, etc.; 2） Selection of the solvent（s） and studying its chemical and physical properties; 3） Design of the optimal flow sheet using a computer simulation; and 4） Combination of process definition and the results of both the simulation and the laboratory experiments for every battery yields the right type of equipment. Experimental proof of the recommended flow sheet, in the adequate equipment, follows-first in a bench-scale, and then in a full scale pilot or demonstration plant. Following of these simple rules ensures a successful development of the process.展开更多
The increasing use of fossil fuels has a significant impact on the environment and ecosystem,which increases the rate of pollution.Given the high potential of renewable energy sources inYemen and the absence of simila...The increasing use of fossil fuels has a significant impact on the environment and ecosystem,which increases the rate of pollution.Given the high potential of renewable energy sources inYemen and the absence of similar studies in the region,this study aims to examine the potential of wind energy in Socotra Island.This was done by analyzing and evaluating wind properties,determining available energy density,calculating wind energy extracted at different altitudes,and then computing the capacity factor for a number of wind turbines and determining the best.The average wind speed in Socotra Island was obtained from the Civil Aviation and Meteorology Authority data,only for the five-year data currently available.The results showed high wind speeds from June to September(9.85-14.88 m/s)while the wind speed decreased for the rest of the year.The average wind speed in the five years was 7.95 m/s.The average annual wind speed,wind energy density,and annual energy density were calculated at different altitudes(10,30,and 50 m).According to the International Wind Energy Rating criteria,the region of Socotra Island falls under Category 7 and is classified as‘Superb’for most of the year.This study provides useful information for developing wind energy and an efficient wind approach.展开更多
This paper deals with the problem of planned lead time calculation in a Material Requirement Planning （MRP） environment under stochastic lead times. The objective is to minimize the sum of holding and backlogging co...This paper deals with the problem of planned lead time calculation in a Material Requirement Planning （MRP） environment under stochastic lead times. The objective is to minimize the sum of holding and backlogging costs. The proposed approach is based on discrete time inventory control where the decision variables are integer. Two types of systems are considered： multi-level serial-production and assembly systems. For the serial production systems （one type of component at each level）, a mathematical model is suggested. Then, it is proven that this model is equivalent to the well known discrete Newsboy Model. This directly provides the optimal values for the planned lead times. For multilevel assembly systems, a dedicated model is proposed and some properties of the decision variables and objective function are proven. These properties are used to calculate lower and upper limits on the decision variables and lower and upper bounds on the objective function. The obtained limits and bounds open the possibility to develop an efficient optimization algorithm using, for example, a Branch and Bound approach. The paper presents the proposed models in detail with corresponding proofs and se＇~eral numerical examples. Some advantages of the suggested models and perspectives of this research are discussed.展开更多
Sea state bias(SSB)is an important component of errors for the radar altimeter measurements of sea surface height(SSH).However,existing SSB estimation methods are almost all based on single-task learning(STL),where on...Sea state bias(SSB)is an important component of errors for the radar altimeter measurements of sea surface height(SSH).However,existing SSB estimation methods are almost all based on single-task learning(STL),where one model is built on the data from only one radar altimeter.In this paper,taking account of the data from multiple radar altimeters available,we introduced a multi-task learning method,called trace-norm regularized multi-task learning(TNR-MTL),for SSB estimation.Corresponding to each individual task,TNR-MLT involves only three parameters.Hence,it is easy to implement.More importantly,the convergence of TNR-MLT is theoretically guaranteed.Compared with the commonly used STL models,TNR-MTL can effectively utilize the shared information between data from multiple altimeters.During the training of TNR-MTL,we used the JASON-2 and JASON-3 cycle data to solve two correlated SSB estimation tasks.Then the optimal model was selected to estimate SSB on the JASON-2 and the HY-270-71 cycle intersection data.For the JSAON-2 cycle intersection data,the corrected variance(M)has been reduced by 0.60 cm^2 compared to the geophysical data records(GDR);while for the HY-2 cycle intersection data,M has been reduced by 1.30 cm^2 compared to GDR.Therefore,TNR-MTL is proved to be effective for the SSB estimation tasks.展开更多
The performances of nonlinear WDM systems with different duty cycle are compared by means of numerical simulation.The numerical results show that the optical pulse with duty cycle of 0.5 is superior to the conventiona...The performances of nonlinear WDM systems with different duty cycle are compared by means of numerical simulation.The numerical results show that the optical pulse with duty cycle of 0.5 is superior to the conventional NRZ modulation scheme.The conclusion is different from that of some references.The reason is that inter symbol interference is not included in some references.In fact,inter symbol interference plays an important role in nonlinear WDM system.Although the larger the duty cycle is ,the stronger the effect of the cross-phase modulation and self-phase modulation on nonlinear WDM is,however,the larger the duty cycle is,the stronger the inter symbol interference is.展开更多
Traffic sector presents a major contributor to air pollution in Palestine. This has been maximized as Israeli closure of major roads resulted in major congestion in most of Palestinian cities in West Bank, which cause...Traffic sector presents a major contributor to air pollution in Palestine. This has been maximized as Israeli closure of major roads resulted in major congestion in most of Palestinian cities in West Bank, which causes high emissions of exhaust gases, such as carbon monoxide （CO）. nitrogen oxides （NOx）. particulate matters （PM）, volatile organic compounds （VOCs） and sulphur dioxide （SO2）. In order that traffic induced pollution can be assessed in Palestine. in this paper, an approach is presented by which the traffic emissions can be estimated relying on the emission factors as input together with vehicle types, annual traveled distance, etc.. The outcomes cover the emission from the various types of vehicles in West Bank.展开更多
Experimental and numerical methods were used to investigate the Magnus phenomena over a spinning projectile.The pressure force acting on the surface of a spinning projectile was measured for various cases by employing...Experimental and numerical methods were used to investigate the Magnus phenomena over a spinning projectile.The pressure force acting on the surface of a spinning projectile was measured for various cases by employing a relatively novel experimental technique.A set of miniature pressure sensors along with a data acquisition board,battery and storage memory were placed inside a spinning model and the surface pressure were obtained through a remotely controlled system.Circumferential pressures of the model for both rotational and static conditions were obtained at two different free stream Mach numbers of 0.4 and 0.8 and at different angles of attack.The results showed the ability of this new test method to measure the very small Magnus force via surface pressures over the projectile.The results provide a deep insight into the flow structure and illustrate changes in the cross-flow separation locations as a result of rotation.Similar results were obtained by the numerical simulations and were compared with the experimental data.展开更多
Objective. The cardinal indication for surgical treatment of gallstones is pain attacks. However, following cholecystectomy, 20%of patients remain symptomatic. It is unclear to what extent post-cholecystectomy symptom...Objective. The cardinal indication for surgical treatment of gallstones is pain attacks. However, following cholecystectomy, 20%of patients remain symptomatic. It is unclear to what extent post-cholecystectomy symptoms can be ascribed to persistence of preoperative symptoms or to new pathology. The pain and digestive pattern in gallstone patients has not been defined in a recent setting with ultrasonography as the diagnostic method. The aim of this study was to characterize a pain pattern that is typical for gallstone disease and to describe the extent of associated dyspepsia. Material and methods. A total of 220 patients with symptomatic gallstone disease including complicated disease (acute cholecystitis and common bile duct stones) were interviewed using detailed questionnaires to disclose pain patterns and symptoms of indigestion. Results. All patients had pain in the right upper quadrant (RUQ) including the upper midline epigastrium. The pain was localized to the right subcostal area in 20%and to the upper epigastrium in 14%, and in the rest (66%) it was more evenly distributed. An area of maximal pain could be defined in 90%. Maximal pain was located under the costal arch in 51%of patients and in the epigastrium in 41%, but in 3%behind the sternum and in 5%in the back. The pain was referred to the back in 63%of the patients. The mean visual analogue scale (VAS) score was very high: 90 mm on a 0-100 scale. A pattern of incipient or low-grade warning pain with a subsequent relatively steady state until subsiding in the same fashion was present in 90%of the patients. An urge to walk around was experienced by 71%. Pain attacks usually occurred in the late evening or at night (77%), with 85%of the attacks lasting for more than one hour and almost never less than half an hour. Sixty-six percent of the patients were intolerant to at least one kind of food, but only 48%to fatty foods. Symptoms of functional indigestion (gastroesophageal reflux, dyspepsia or irritable bowel symptoms) were seen in the vast majority i展开更多
Serrated flow of Al-Li single crystals was investigated under different aging conditions,temperatures(T)and strain rates(ε).The results show that dynamic strain aging(DSA)of solute Li atoms alone is not strong enough...Serrated flow of Al-Li single crystals was investigated under different aging conditions,temperatures(T)and strain rates(ε).The results show that dynamic strain aging(DSA)of solute Li atoms alone is not strong enough to make the serrated flow at solid solution state.The occurrence of the serrated flow is related to the shearing ofδ'particles.Critical strain of serration can change normally or inversely with T and e,which indicates the serration in Al-Li alloys is a thermally activated process.A proposed mechanism for the occurrence of the serration is that mobile dislocations are pinned when they cross the shearedδ'particles that might be dissolved during deformation,thus induce the serrated flow in the Al-Li single crystal.展开更多
With the rapid development of Internet technology,users have an increasing demand for data.The continuous popularization of traffic-intensive applications such as high-definition video,3D visualization,and cloud compu...With the rapid development of Internet technology,users have an increasing demand for data.The continuous popularization of traffic-intensive applications such as high-definition video,3D visualization,and cloud computing has promoted the rapid evolution of the communications industry.In order to cope with the huge traffic demand of today’s users,5G networks must be fast,flexible,reliable and sustainable.Based on these research backgrounds,the academic community has proposed D2D communication.The main feature of D2D communication is that it enables direct communication between devices,thereby effectively improve resource utilization and reduce the dependence on base stations,so it can effectively improve the throughput of multimedia data.One of the most considerable factor which affects the performance of D2D communication is the co-channel interference which results due to the multiplexing of multiple D2D user using the same channel resource of the cellular user.To solve this problem,this paper proposes a joint algorithm time scheduling and power control.The main idea is to effectively maximize the number of allocated resources in each scheduling period with satisfied quality of service requirements.The constraint problem is decomposed into time scheduling and power control subproblems.The power control subproblem has the characteristics of mixed-integer linear programming of NP-hard.Therefore,we proposed a gradual power control method.The time scheduling subproblem belongs to the NP-hard problem having convex-cordinality,therefore,we proposed a heuristic scheme to optimize resource allocation.Simulation results show that the proposed algorithm effectively improved the resource allocation and overcome the co-channel interference as compared with existing algorithms.展开更多
Background: The pathogenesis of chronic hepatitis C virus (HCV) infection is associated with a defective host antiviral immune response and intrahepatic oxidative stress. Oxidative stress and lipid peroxidation play m...Background: The pathogenesis of chronic hepatitis C virus (HCV) infection is associated with a defective host antiviral immune response and intrahepatic oxidative stress. Oxidative stress and lipid peroxidation play major roles in the fatty liver accumulation (steatosis) that leads to necro-inflammation and necrosis of hepatic cells. Previous trials suggested that antioxidative therapy may have a beneficial effect on patients with chronic HCV infection. Aims: To determine the safety and efficacy of treatment of chronic HCV patients via a combination of antioxidants. Methods: Fifty chronic HCV patients were treated orally on a daily basis for 20 weeks with seven antioxidative oral preparations (glycyrrhizin, schisandra, silymarin, ascorbic acid, lipoic acid, L-glutathione, and alpha-tocopherol), along with four different intravenous preparations (glycyrrhizin, ascorbic acid, L-glutathione, B-complex) twice weekly for the first 10 weeks, and followed-up for an additional 20 weeks. Patients were monitored for HCV-RNA levels, liver enzymes, and liver histology. Assessment of quality of life was performed using the SF-36 questionnaire. Results: In one of the tested parameters (eg, liver enzymes, HCV PvNA levels, or liver biopsy score), a combination of antioxidants induced a favorable response in 48% of the patients (24). Normalization of liver enzymes occurred in 44% of patients who had elevated pretreatment ALT levels (15 of 34). ALT levels remained normal throughout follow-up period in 72.7% (8 of 11). A decrease in viral load (one log or more) was observed in 25% of the patients (12). Histologic improvement (2-point reduction in the HAI score) was noted in 36.1% of the patients. The SF-36 score improved in 26 of 45 patients throughout the course of the trial (58% of the patients). Treatment was well tolerated by all patients. No major adverse reactions were noted. Conclusions: These data suggest that multi antioxidative treatment in chronic HCV patients is well tolerated and may have a beneficial effect on necro-i展开更多
The flow patterns and wake structures behind a pitching airfoil in an un-bounded domain have been studied extensively. In contrast, the flow phenomena associated with a pitching airfoil near a solid boundary have not ...The flow patterns and wake structures behind a pitching airfoil in an un-bounded domain have been studied extensively. In contrast, the flow phenomena associated with a pitching airfoil near a solid boundary have not been adequately studied or reported. This paper aims at filling this research gap by considering the flow confinement effects on the flow pattern around a pitching airfoil. To achieve this goal, the flow fields around a flapping airfoil in un-bounded, bounded and semi-bounded domains are studied and compared. Numerical simulations are carried out at a fixed Reynolds number, Re = 255, and at a fixed oscillation frequency corresponding to St = 0.22. An accurate immersed boundary method is employed to calculate the unsteady flow fields around the airfoil at various flapping amplitudes. It is argued that two flow mechanisms, here called ＂the interaction effect＂ and ＂the induced reverse flow effect＂ are responsible for the variations of the flow field due to the presence of a nearby solid boundary.展开更多
PURPOSE: To compare the prevalence of keratoconjunctivitis sicca (KCS) in a pr ospective cohort of 22,382 diabetic patients with that in the general population . DESIGN: Prospective, observational, cohort study. METHO...PURPOSE: To compare the prevalence of keratoconjunctivitis sicca (KCS) in a pr ospective cohort of 22,382 diabetic patients with that in the general population . DESIGN: Prospective, observational, cohort study. METHODS: setting: A district of Israel’s largest health maintenance organization. study population: We foll owed the electronic medical records of all patients in the district older than 5 0 years (159,634 patients)between January 1 and December 31, 2003. Of those, 22, 382 (14.0%) had diabetes. observation procedure: The proportion of ocular lubri cation consumers was compared among diabetic and nondiabetic patients. All HbA1c laboratory tests performed by the diabetic patients were documented (41,910 tes ts), and glycemic control was correlated with the consumption of ocular lubricat ion. main outcome measures: Ocular lubrication use by diabetic patients compared with the general population and the relationship between glycemic control and o cular lubrication use. RESULTS: After age and gender adjustment, a significantly higher percentage of diabetic patients (20.6%) received ocular lubrication, co mpared with nondiabetic patients (13.8%, P< .001). The difference was significa nt for all age groups and for both sexes (P< .001). A similar significant differ ence was prominent between diabetic and nondiabetic patients aged 60 to 89 years who were frequent users of ocular lubrication. Ocular lubrication consumption i ncreased with poorer glycemic control (mean annual HbA1c levels). Multivariate a nalysis revealed this effect to be independent of age, sex, place of birth, or p lace of residence. CONCLUSIONS: KCS is significantly more common among diabetic patients. Poor glycemic control correlates with increased artificial tear use in diabetic patients.展开更多
基金Project supported by PAZY Foundation,Israel(244)
文摘Two types of cyanobacteria of the genus Arthrospira（commonly known as Spirulina） were tested for biosorption of cerium（III） ions from aqueous solutions. An endemic type（ES） found in the northern Negev desert, Israel, and a commercial powder（CS） were used in this study. Biosorption was evaluated as a function of p H, contact time, initial metal concentration, number of sorption-desorption cycles, and salt concentration. The optimum p H range for biosorption was found to be 5.0–5.5. The kinetic characteristics of both Spirulina types were found to be highly compatible with a pseudo-second order kinetic model. The adsorption isotherms of both types were found to be well-suited to Langmuir and Freundlich adsorption isotherms. Maximum biosorption uptakes, according to the Langmuir model, were 18.1 and 38.2 mg/g, for ES and CS, respectively. Sodium chloride concentrations of up to 5 g/L had a minor effect on cerium biosorption. Desorption efficiency was found to be greater than 97% with 0.1 mol/L HNO_3 after three sorption-desorption cycles, without significant loss in the biosorption capacity. The results indicated the feasibility of cerium recovery from industrial wastes using Spirulina biomass.
基金supported by Consejo Nacional de Ciencia yTecnologia or National Council of Science and Technology(CONACYT,175925)
文摘Doped and undoped TiCh nanoparticles were prepared by Stober method and thermally treated at 600 ℃.The effect of Nd^（3＋） ion on the structure and micro structure of anatase-phase TiCh nanocrystals was studied by Rietveld refinement method using X-ray powder diffraction data.Bond lengths,bond angles,and edges distances were analyzed.The phase formation was confirmed by high-resolution transmission electron microscopy.The adjustment of Ti-0 bond length induced by the addition of Nd^（3＋） ions,reduced the octahedral distortion and altered the octahedral array in the anatase-phase TiCh nanocrystal.The changes of structure and microstructure were mainly observed for TiCh nanoparticles doped with 0.1 at.%of Nd^（3＋） ions and attributed to the cationic substitution of Ti^（4＋） ions which promoted changes in the density of states and gap band of TiCh.The dopant insertion resulted in a better structural stability of the nanocrystals that enhanced their charge transference and photocatalytic efficiency.
基金Project supported by the National Natural Science Foundation of China （Grant Nos 10574018 and 10574020）.
文摘This paper studies the process of mutual neutralization of Si^＋ and H^- ions in slow collisions within the multichannel Landau-Zener model. All important ionic-covalent couplings in this collision system are included in the collision dynamics. The cross sections for population of specific final states of product Si atom are calculated in the CM energy range 0.05 e∨/u-5 ke∨/u. Both singlet and triplet states are considered. At collision energies below -10 e∨/u, the most populated singlet state is Si（3p4p, ^1S0）, while for energies above -150e∨/u it is the Si（3p, 4p, ^1P1） state. In the case of triplet states, the mixed 3p4p（^3S1 ＋^3P0） states are the most populated in the entire collision energy range investigated. The total cross section exhibits a broad maximum around 200 300e∨/u and for ECM ≤ 10e∨/u it monotonically increases with decreasing the collision energy, reaching a value of 8 × 10^-13 cm^2 at ECM = 0.05 e∨/u. The ion-pair formation process in Si（3p^2 ^3PJ）＋H（1s） collisions has also been considered and its cross section in the considered energy range is very small （smaller than 10^-20 cm^2 in the energy region below 1 ke∨/u）.
基金Supported by the following projects:Proiect IDEI(56/07.10.2011)the IFA project Romania-CERN(7/16.03.2016)(LHCb-Ro)
文摘In this paper we present a comparative study between PYTHIA, EPOS, QGSJET, and SIBYLL generators. The global event observables considered are the charged energy flow, charged particle distributions, charged hadron production ratios and V^0 ratios. The study is performed in the LHCb and TOTEM fiducial phase spaces on minimum bias simulated data samples for pp collisions at = 7 TeV , using the reference measurements from these experiments. In the majority of cases, the measurements are within a band defined by the most extreme predictions. The observed differences between the predictions and the measurements seem to be, in most part, caused by extrapolation from the central pseudorapidity region (|η| 2.5), in which the generators were mainly tuned.
基金supported by the National Basic Research Program of China("973"Program)(Grant No.2011CB707204)the National Natural Science Foundation of China(Grant No.50706020)
文摘Recovery of heat energy from internal combustion engine exhaust will achieve significant road transportation CO2 reduction. Turbocharging and turbogenerating are most commonly used technologies to recover engine exhaust heat energy.Engine exhaust pulse flow can significantly affect the turbine performance of turbocharging and turbogenerating systems,and it is necessary to consider the pulse flow effects in turbine design and performance analysis.An investigation was carried out by numerical simulation on the mixed flow turbine pulse flow performance and flow fields.Results showed that the variations of the turbine efficiency and flowfiled under pulsating flow conditions demonstrate significant unsteady effects.The effect of blade leading edge sweep on turbine pulse flow performance was studied.It is shown that increasing of the leading edge sweep angle can improve the turbine average instantaneous efficiency by about 2 percent under pulsating flow conditions.
文摘The objective of the integrated approach is to minimize the cost and duration of the development of the final flow sheet by optimal allocation of the resources to various steps of the development. In the integrated approach, the development of a solvent extraction （SX） flow sheet is done in the following order： 1） Definition of the process： composition of the feed, specification of the product, minimum yield, etc.; 2） Selection of the solvent（s） and studying its chemical and physical properties; 3） Design of the optimal flow sheet using a computer simulation; and 4） Combination of process definition and the results of both the simulation and the laboratory experiments for every battery yields the right type of equipment. Experimental proof of the recommended flow sheet, in the adequate equipment, follows-first in a bench-scale, and then in a full scale pilot or demonstration plant. Following of these simple rules ensures a successful development of the process.
基金The author extends his appreciation to the Deanship of Scientific Research at King Khalid University for funding this work under Grant Number(R.G.P.2/25/42),Received by Fahd N.Al-Wesabi.www.kku.edu.sa.
文摘The increasing use of fossil fuels has a significant impact on the environment and ecosystem,which increases the rate of pollution.Given the high potential of renewable energy sources inYemen and the absence of similar studies in the region,this study aims to examine the potential of wind energy in Socotra Island.This was done by analyzing and evaluating wind properties,determining available energy density,calculating wind energy extracted at different altitudes,and then computing the capacity factor for a number of wind turbines and determining the best.The average wind speed in Socotra Island was obtained from the Civil Aviation and Meteorology Authority data,only for the five-year data currently available.The results showed high wind speeds from June to September(9.85-14.88 m/s)while the wind speed decreased for the rest of the year.The average wind speed in the five years was 7.95 m/s.The average annual wind speed,wind energy density,and annual energy density were calculated at different altitudes(10,30,and 50 m).According to the International Wind Energy Rating criteria,the region of Socotra Island falls under Category 7 and is classified as‘Superb’for most of the year.This study provides useful information for developing wind energy and an efficient wind approach.
文摘This paper deals with the problem of planned lead time calculation in a Material Requirement Planning （MRP） environment under stochastic lead times. The objective is to minimize the sum of holding and backlogging costs. The proposed approach is based on discrete time inventory control where the decision variables are integer. Two types of systems are considered： multi-level serial-production and assembly systems. For the serial production systems （one type of component at each level）, a mathematical model is suggested. Then, it is proven that this model is equivalent to the well known discrete Newsboy Model. This directly provides the optimal values for the planned lead times. For multilevel assembly systems, a dedicated model is proposed and some properties of the decision variables and objective function are proven. These properties are used to calculate lower and upper limits on the decision variables and lower and upper bounds on the objective function. The obtained limits and bounds open the possibility to develop an efficient optimization algorithm using, for example, a Branch and Bound approach. The paper presents the proposed models in detail with corresponding proofs and se＇~eral numerical examples. Some advantages of the suggested models and perspectives of this research are discussed.
基金This work was supported by the Major Project for New Generation of AI(No.2018AAA0100400)the National Natural Science Foundation of China(No.41706010)+1 种基金the Joint Fund of the Equipments Pre-Research and Ministry of Education of China(No.6141A020337)and the Fundamental Research Funds for the Central Universities of China.
文摘Sea state bias(SSB)is an important component of errors for the radar altimeter measurements of sea surface height(SSH).However,existing SSB estimation methods are almost all based on single-task learning(STL),where one model is built on the data from only one radar altimeter.In this paper,taking account of the data from multiple radar altimeters available,we introduced a multi-task learning method,called trace-norm regularized multi-task learning(TNR-MTL),for SSB estimation.Corresponding to each individual task,TNR-MLT involves only three parameters.Hence,it is easy to implement.More importantly,the convergence of TNR-MLT is theoretically guaranteed.Compared with the commonly used STL models,TNR-MTL can effectively utilize the shared information between data from multiple altimeters.During the training of TNR-MTL,we used the JASON-2 and JASON-3 cycle data to solve two correlated SSB estimation tasks.Then the optimal model was selected to estimate SSB on the JASON-2 and the HY-270-71 cycle intersection data.For the JSAON-2 cycle intersection data,the corrected variance(M)has been reduced by 0.60 cm^2 compared to the geophysical data records(GDR);while for the HY-2 cycle intersection data,M has been reduced by 1.30 cm^2 compared to GDR.Therefore,TNR-MTL is proved to be effective for the SSB estimation tasks.
文摘The performances of nonlinear WDM systems with different duty cycle are compared by means of numerical simulation.The numerical results show that the optical pulse with duty cycle of 0.5 is superior to the conventional NRZ modulation scheme.The conclusion is different from that of some references.The reason is that inter symbol interference is not included in some references.In fact,inter symbol interference plays an important role in nonlinear WDM system.Although the larger the duty cycle is ,the stronger the effect of the cross-phase modulation and self-phase modulation on nonlinear WDM is,however,the larger the duty cycle is,the stronger the inter symbol interference is.
文摘Traffic sector presents a major contributor to air pollution in Palestine. This has been maximized as Israeli closure of major roads resulted in major congestion in most of Palestinian cities in West Bank, which causes high emissions of exhaust gases, such as carbon monoxide （CO）. nitrogen oxides （NOx）. particulate matters （PM）, volatile organic compounds （VOCs） and sulphur dioxide （SO2）. In order that traffic induced pollution can be assessed in Palestine. in this paper, an approach is presented by which the traffic emissions can be estimated relying on the emission factors as input together with vehicle types, annual traveled distance, etc.. The outcomes cover the emission from the various types of vehicles in West Bank.
文摘Experimental and numerical methods were used to investigate the Magnus phenomena over a spinning projectile.The pressure force acting on the surface of a spinning projectile was measured for various cases by employing a relatively novel experimental technique.A set of miniature pressure sensors along with a data acquisition board,battery and storage memory were placed inside a spinning model and the surface pressure were obtained through a remotely controlled system.Circumferential pressures of the model for both rotational and static conditions were obtained at two different free stream Mach numbers of 0.4 and 0.8 and at different angles of attack.The results showed the ability of this new test method to measure the very small Magnus force via surface pressures over the projectile.The results provide a deep insight into the flow structure and illustrate changes in the cross-flow separation locations as a result of rotation.Similar results were obtained by the numerical simulations and were compared with the experimental data.
文摘Objective. The cardinal indication for surgical treatment of gallstones is pain attacks. However, following cholecystectomy, 20%of patients remain symptomatic. It is unclear to what extent post-cholecystectomy symptoms can be ascribed to persistence of preoperative symptoms or to new pathology. The pain and digestive pattern in gallstone patients has not been defined in a recent setting with ultrasonography as the diagnostic method. The aim of this study was to characterize a pain pattern that is typical for gallstone disease and to describe the extent of associated dyspepsia. Material and methods. A total of 220 patients with symptomatic gallstone disease including complicated disease (acute cholecystitis and common bile duct stones) were interviewed using detailed questionnaires to disclose pain patterns and symptoms of indigestion. Results. All patients had pain in the right upper quadrant (RUQ) including the upper midline epigastrium. The pain was localized to the right subcostal area in 20%and to the upper epigastrium in 14%, and in the rest (66%) it was more evenly distributed. An area of maximal pain could be defined in 90%. Maximal pain was located under the costal arch in 51%of patients and in the epigastrium in 41%, but in 3%behind the sternum and in 5%in the back. The pain was referred to the back in 63%of the patients. The mean visual analogue scale (VAS) score was very high: 90 mm on a 0-100 scale. A pattern of incipient or low-grade warning pain with a subsequent relatively steady state until subsiding in the same fashion was present in 90%of the patients. An urge to walk around was experienced by 71%. Pain attacks usually occurred in the late evening or at night (77%), with 85%of the attacks lasting for more than one hour and almost never less than half an hour. Sixty-six percent of the patients were intolerant to at least one kind of food, but only 48%to fatty foods. Symptoms of functional indigestion (gastroesophageal reflux, dyspepsia or irritable bowel symptoms) were seen in the vast majority i
基金Supported by the National Natural Science Foundation of China。
文摘Serrated flow of Al-Li single crystals was investigated under different aging conditions,temperatures(T)and strain rates(ε).The results show that dynamic strain aging(DSA)of solute Li atoms alone is not strong enough to make the serrated flow at solid solution state.The occurrence of the serrated flow is related to the shearing ofδ'particles.Critical strain of serration can change normally or inversely with T and e,which indicates the serration in Al-Li alloys is a thermally activated process.A proposed mechanism for the occurrence of the serration is that mobile dislocations are pinned when they cross the shearedδ'particles that might be dissolved during deformation,thus induce the serrated flow in the Al-Li single crystal.
基金The corresponding authors Bong Jun Choi and Ehab Mahmood Mohammad would like to thank their institutes(Soongsil University,South Korea&Aswan University,Egypt)for supporting this article.
文摘With the rapid development of Internet technology,users have an increasing demand for data.The continuous popularization of traffic-intensive applications such as high-definition video,3D visualization,and cloud computing has promoted the rapid evolution of the communications industry.In order to cope with the huge traffic demand of today’s users,5G networks must be fast,flexible,reliable and sustainable.Based on these research backgrounds,the academic community has proposed D2D communication.The main feature of D2D communication is that it enables direct communication between devices,thereby effectively improve resource utilization and reduce the dependence on base stations,so it can effectively improve the throughput of multimedia data.One of the most considerable factor which affects the performance of D2D communication is the co-channel interference which results due to the multiplexing of multiple D2D user using the same channel resource of the cellular user.To solve this problem,this paper proposes a joint algorithm time scheduling and power control.The main idea is to effectively maximize the number of allocated resources in each scheduling period with satisfied quality of service requirements.The constraint problem is decomposed into time scheduling and power control subproblems.The power control subproblem has the characteristics of mixed-integer linear programming of NP-hard.Therefore,we proposed a gradual power control method.The time scheduling subproblem belongs to the NP-hard problem having convex-cordinality,therefore,we proposed a heuristic scheme to optimize resource allocation.Simulation results show that the proposed algorithm effectively improved the resource allocation and overcome the co-channel interference as compared with existing algorithms.
文摘Background: The pathogenesis of chronic hepatitis C virus (HCV) infection is associated with a defective host antiviral immune response and intrahepatic oxidative stress. Oxidative stress and lipid peroxidation play major roles in the fatty liver accumulation (steatosis) that leads to necro-inflammation and necrosis of hepatic cells. Previous trials suggested that antioxidative therapy may have a beneficial effect on patients with chronic HCV infection. Aims: To determine the safety and efficacy of treatment of chronic HCV patients via a combination of antioxidants. Methods: Fifty chronic HCV patients were treated orally on a daily basis for 20 weeks with seven antioxidative oral preparations (glycyrrhizin, schisandra, silymarin, ascorbic acid, lipoic acid, L-glutathione, and alpha-tocopherol), along with four different intravenous preparations (glycyrrhizin, ascorbic acid, L-glutathione, B-complex) twice weekly for the first 10 weeks, and followed-up for an additional 20 weeks. Patients were monitored for HCV-RNA levels, liver enzymes, and liver histology. Assessment of quality of life was performed using the SF-36 questionnaire. Results: In one of the tested parameters (eg, liver enzymes, HCV PvNA levels, or liver biopsy score), a combination of antioxidants induced a favorable response in 48% of the patients (24). Normalization of liver enzymes occurred in 44% of patients who had elevated pretreatment ALT levels (15 of 34). ALT levels remained normal throughout follow-up period in 72.7% (8 of 11). A decrease in viral load (one log or more) was observed in 25% of the patients (12). Histologic improvement (2-point reduction in the HAI score) was noted in 36.1% of the patients. The SF-36 score improved in 26 of 45 patients throughout the course of the trial (58% of the patients). Treatment was well tolerated by all patients. No major adverse reactions were noted. Conclusions: These data suggest that multi antioxidative treatment in chronic HCV patients is well tolerated and may have a beneficial effect on necro-i
文摘The flow patterns and wake structures behind a pitching airfoil in an un-bounded domain have been studied extensively. In contrast, the flow phenomena associated with a pitching airfoil near a solid boundary have not been adequately studied or reported. This paper aims at filling this research gap by considering the flow confinement effects on the flow pattern around a pitching airfoil. To achieve this goal, the flow fields around a flapping airfoil in un-bounded, bounded and semi-bounded domains are studied and compared. Numerical simulations are carried out at a fixed Reynolds number, Re = 255, and at a fixed oscillation frequency corresponding to St = 0.22. An accurate immersed boundary method is employed to calculate the unsteady flow fields around the airfoil at various flapping amplitudes. It is argued that two flow mechanisms, here called ＂the interaction effect＂ and ＂the induced reverse flow effect＂ are responsible for the variations of the flow field due to the presence of a nearby solid boundary.
文摘PURPOSE: To compare the prevalence of keratoconjunctivitis sicca (KCS) in a pr ospective cohort of 22,382 diabetic patients with that in the general population . DESIGN: Prospective, observational, cohort study. METHODS: setting: A district of Israel’s largest health maintenance organization. study population: We foll owed the electronic medical records of all patients in the district older than 5 0 years (159,634 patients)between January 1 and December 31, 2003. Of those, 22, 382 (14.0%) had diabetes. observation procedure: The proportion of ocular lubri cation consumers was compared among diabetic and nondiabetic patients. All HbA1c laboratory tests performed by the diabetic patients were documented (41,910 tes ts), and glycemic control was correlated with the consumption of ocular lubricat ion. main outcome measures: Ocular lubrication use by diabetic patients compared with the general population and the relationship between glycemic control and o cular lubrication use. RESULTS: After age and gender adjustment, a significantly higher percentage of diabetic patients (20.6%) received ocular lubrication, co mpared with nondiabetic patients (13.8%, P< .001). The difference was significa nt for all age groups and for both sexes (P< .001). A similar significant differ ence was prominent between diabetic and nondiabetic patients aged 60 to 89 years who were frequent users of ocular lubrication. Ocular lubrication consumption i ncreased with poorer glycemic control (mean annual HbA1c levels). Multivariate a nalysis revealed this effect to be independent of age, sex, place of birth, or p lace of residence. CONCLUSIONS: KCS is significantly more common among diabetic patients. Poor glycemic control correlates with increased artificial tear use in diabetic patients.
