In this paper, the problem of finding exact solutions to the magnetohydrodynamic(MHD) equations in the presence of incompressible mass flows with helical symmetry is considered. For ideal flows, a similarity reduction...In this paper, the problem of finding exact solutions to the magnetohydrodynamic(MHD) equations in the presence of incompressible mass flows with helical symmetry is considered. For ideal flows, a similarity reduction method is used to obtain exact solutions for several MHD flows with nonlinear variable Mach number. For resistive flows parallel to a magnetic field, the governing equilibrium equation is derived. The MHD equilibrium state of a helically symmetric incompressible flow is governed by a second-order elliptic partial differential equation(PDE) for the helical magnetic flux function. Exact solutions for the latter equation are obtained. Also, the equilibrium equations of a gravitating plasma with incompressible flow are derived.展开更多
Scientific workflows have gained the emerging attention in sophisti-cated large-scale scientific problem-solving environments.The pay-per-use model of cloud,its scalability and dynamic deployment enables it suited for ex...Scientific workflows have gained the emerging attention in sophisti-cated large-scale scientific problem-solving environments.The pay-per-use model of cloud,its scalability and dynamic deployment enables it suited for executing scientific workflow applications.Since the cloud is not a utopian environment,failures are inevitable that may result in experiencingfluctuations in the delivered performance.Though a single task failure occurs in workflow based applications,due to its task dependency nature,the reliability of the overall system will be affected drastically.Hence rather than reactive fault-tolerant approaches,proactive measures are vital in scientific workflows.This work puts forth an attempt to con-centrate on the exploration issue of structuring a nature inspired metaheuristics-Intelligent Water Drops Algorithm(IWDA)combined with an efficient machine learning approach-Support Vector Regression(SVR)for task failure prognostica-tion which facilitates proactive fault-tolerance in the scheduling of scientific workflow applications.The failure prediction models in this study have been implemented through SVR-based machine learning approaches and the precision accuracy of prediction is optimized by IWDA and several performance metrics were evaluated on various benchmark workflows.The experimental results prove that the proposed proactive fault-tolerant approach performs better compared with the other existing techniques.展开更多
OWS(OGC Web Service)为空间数据共享提供了可行的方法,但如何在浩瀚的互联网上快速、准确地查询到符合用户需要的OWS是一件比较困难的事情。在对Web搜索方法进行深入理解的基础上,提出一种基于全文检索搜索引擎搭建OWS索引服务的思路,...OWS(OGC Web Service)为空间数据共享提供了可行的方法,但如何在浩瀚的互联网上快速、准确地查询到符合用户需要的OWS是一件比较困难的事情。在对Web搜索方法进行深入理解的基础上,提出一种基于全文检索搜索引擎搭建OWS索引服务的思路,并采用Google实现了OWS索引服务中心的原型系统,该系统可以为互联网用户提供OWS搜索服务。展开更多
随着网络技术的不断成熟,许多新技术成功地运用到GIS系统的客户端数据展现当中,而最引人注目的技术就是A-JAX;另一方面,开放地理信息系统联盟(OGC)开发了一系列基于Web服务技术的地理空间数据互操作协议OGC Web Services(OWS),其中的Web...随着网络技术的不断成熟,许多新技术成功地运用到GIS系统的客户端数据展现当中,而最引人注目的技术就是A-JAX;另一方面,开放地理信息系统联盟(OGC)开发了一系列基于Web服务技术的地理空间数据互操作协议OGC Web Services(OWS),其中的Web Map Services(WMS)已经广泛地应用于GIS领域。本文首先对于AJAX技术和OWS规范进行基础性的阐述,之后将详细介绍一个结合AJAX技术和OWS规范构造的GIS系统—ACT-GIS。展开更多
Considering the influence of the streaming potential and electroviscous effects, the analytical solutions for electromagnetohydrodynamic (EMHD) flows in parallel plate microchannels are obtained. The electrolyte solut...Considering the influence of the streaming potential and electroviscous effects, the analytical solutions for electromagnetohydrodynamic (EMHD) flows in parallel plate microchannels are obtained. The electrolyte solutions in the microchannels are taken as generalized Maxwell fluids, and slip boundary conditions are adopted. To accurately analyze the EMHD flow characteristics, the variation trends of the electroviscous effects with the corresponding parameters must be understood. The results show that the electroviscous effects increase with the increase in the relaxation time De, the slip coefficient , and the wall zeta potential 0. However, the increase in the inverse of the electrical double-layer (EDL) thickness K, the electrical oscillating Reynolds number Re, and the ionic P'eclet number Pe can decrease the electroviscous effects. We also demonstrate that the electroviscous effect on the EMHD flows of generalized Maxwell fluids is larger than that of Newtonian fluids. This work will be useful in designing EMHD flows in parallel plate microchannels.展开更多
Traditional transgenic detection methods require high test conditions and struggle to be both sensitive and efficient.In this study,a one-tube dual recombinase polymerase amplification(RPA)reaction system for CP4-EPSP...Traditional transgenic detection methods require high test conditions and struggle to be both sensitive and efficient.In this study,a one-tube dual recombinase polymerase amplification(RPA)reaction system for CP4-EPSPS and Cry1Ab/Ac was proposed and combined with a lateral flow immunochromatographic assay,named“Dual-RPA-LFD”,to visualize the dual detection of genetically modified(GM)crops.In which,the herbicide tolerance gene CP4-EPSPS and the insect resistance gene Cry1Ab/Ac were selected as targets taking into account the current status of the most widespread application of insect resistance and herbicide tolerance traits and their stacked traits.Gradient diluted plasmids,transgenic standards,and actual samples were used as templates to conduct sensitivity,specificity,and practicality assays,respectively.The constructed method achieved the visual detection of plasmid at levels as low as 100 copies,demonstrating its high sensitivity.In addition,good applicability to transgenic samples was observed,with no cross-interference between two test lines and no influence from other genes.In conclusion,this strategy achieved the expected purpose of simultaneous detection of the two popular targets in GM crops within 20 min at 37°C in a rapid,equipmentfree field manner,providing a new alternative for rapid screening for transgenic assays in the field.展开更多
Non-flow aqueous zinc-bromine batteries without auxiliary components(e.g.,pumps,pipes,storage tanks)and ion-selective membranes represent a cost-effective and promising technology for large-scale energy storage.Unfort...Non-flow aqueous zinc-bromine batteries without auxiliary components(e.g.,pumps,pipes,storage tanks)and ion-selective membranes represent a cost-effective and promising technology for large-scale energy storage.Unfortunately,they generally suffer from serious diffusion and shuttle of polybromide(Br^(-),Br^(3-))due to the weak physical adsorption between soluble polybromide and host carbon materials,which results in low energy efficiency and poor cycling stability.Here,we develop a novel self-capture organic bromine material(1,10-bis[3-(trimethylammonio)propyl]-4,4'-bipyridinium bromine,NVBr4)to successfully realize reversible solid complexation of bromide components for stable non-flow zinc-bromine battery applications.The quaternary ammonium groups(NV^(4+)ions)can effectively capture the soluble polybromide species based on strong chemical interaction and realize reversible solid complexation confined within the porous electrodes,which transforms the conventional“liquid-liquid”conversion of soluble bromide components into“liquid-solid”model and effectively suppresses the shuttle effect.Thereby,the developed non-flow zinc-bromide battery provides an outstanding voltage platform at 1.7 V with a notable specific capacity of 325 mAh g^(-1)NVBr4(1 A g^(-1)),excellent rate capability(200 mAh g^(-1)NVBr4 at 20 A g^(-1)),outstanding energy density of 469.6 Wh kg^(-1)and super-stable cycle life(20,000 cycles with 100%Coulombic efficiency),which outperforms most of reported zinc-halogen batteries.Further mechanism analysis and DFT calculations demonstrate that the chemical interaction of quaternary ammonium groups and bromide species is the main reason for suppressing the shuttle effect.The developed strategy can be extended to other halogen batteries to obtain stable charge storage.展开更多
Hydrodynamics characterization in terms offlow regime behavior is a crucial task to enhance the design of bubble column reactors and scaling up related methodologies.This review presents recent studies on the typicalflo...Hydrodynamics characterization in terms offlow regime behavior is a crucial task to enhance the design of bubble column reactors and scaling up related methodologies.This review presents recent studies on the typicalflow regimes established in bubble columns.Some effort is also provided to introduce relevant definitions pertaining to thisfield,namely,that of“void fraction”and related(local,chordal,cross-sectional and volumetric)variants.Experimental studies involving different parameters that affect design and operating conditions are also discussed in detail.In the second part of the review,the attention is shifted to cases with internals of various types(perfo-rated plates,baffles,vibrating helical springs,mixers,and heat exchanger tubes)immersed in the bubble columns.It is shown that the presence of these elements has a limited influence on the global column hydrodynamics.However,they can make the homogeneousflow regime more stable in terms of transition gas velocity and transi-tion holdup value.The last section is used to highlight gaps which have not beenfilled yet and future directions of investigation.展开更多
Ensuring a stable power output from renewable energy sources,such as wind and solar energy,depends on the development of large-scale and long-duration energy storage devices.Zinc–bromine fl ow batteries(ZBFBs)have em...Ensuring a stable power output from renewable energy sources,such as wind and solar energy,depends on the development of large-scale and long-duration energy storage devices.Zinc–bromine fl ow batteries(ZBFBs)have emerged as cost-eff ective and high-energy-density solutions,replacing expensive all-vanadium fl ow batteries.However,uneven Zn deposition during charging results in the formation of problematic Zn dendrites,leading to mass transport polarization and self-discharge.Stable Zn plating and stripping are essential for the successful operation of high-areal-capacity ZBFBs.In this study,we successfully synthesized nitrogen and oxygen co-doped functional carbon felt(NOCF4)electrode through the oxidative polymerization of dopamine,followed by calcination under ambient conditions.The NOCF4 electrode eff ectively facilitates effi cient“shuttle deposition”of Zn during charging,signifi cantly enhancing the areal capacity of the electrode.Remarkably,ZBFBs utilizing NOCF4 as the anode material exhibited stable cycling performance for 40 cycles(approximately 240 h)at an areal capacity of 60 mA h/cm^(2).Even at a high areal capacity of 130 mA h/cm^(2),an impressive energy effi ciency of 76.98%was achieved.These fi ndings provide a promising pathway for the development of high-areal-capacity ZBFBs for advanced energy storage systems.展开更多
Aqueous redox-active organic materials-base electrolytes are sustainable alternatives to vanadium-based electrolyte for redoxflow batteries(RFBs)due to the advantages of high ionic conductivity,environmentally benign,s...Aqueous redox-active organic materials-base electrolytes are sustainable alternatives to vanadium-based electrolyte for redoxflow batteries(RFBs)due to the advantages of high ionic conductivity,environmentally benign,safety and low cost.However,the underexplored redox properties of organic materials and the narrow thermodynamic electrolysis window of water(1.23 V)hinder their wide applications.Therefore,seeking suitable organic redox couples and aqueous electrolytes with a high output voltage is highly suggested for advancing the aqueous organic RFBs.In this work,the functionalized phenazine and nitroxyl radical with electron-donating and electron-withdrawing group exhibit redox potential of-0.88 V and 0.78 V vs.Ag,respectively,in“water-in-ionic liquid”supporting electrolytes.Raman spectra reveal that the activity of water is largely suppressed in“water-in-ionic liquid”due to the enhanced hydrogen bond interactions between ionic liquid and water,enabling an electrochemical stability window above 3 V.“Water-in-ionic liquid”supporting electrolytes help to shift redox potential of nitroxyl radical and enable the redox activity of functionalized phenazine.The assembled aqueous RFB allows a theoretical cell voltage of 1.66 V and shows a practical discharge voltage of 1.5 V in the“water-in-ionic liquid”electrolytes.Meanwhile,capacity retention of 99.91%per cycle is achieved over 500 charge/discharge cycles.A power density of 112 mW cm^(-2) is obtained at a current density of 30 mA cm^(-2).This work highlights the importance of rationally combining supporting electrolytes and organic molecules to achieve high-voltage aqueous RFBs.展开更多
The gas-water two-phaseflow occurring as a result of fracturingfluidflowback phenomena is known to impact significantly the productivity of shale gas well.In this work,this two-phaseflow has been simulated in the framework...The gas-water two-phaseflow occurring as a result of fracturingfluidflowback phenomena is known to impact significantly the productivity of shale gas well.In this work,this two-phaseflow has been simulated in the framework of a hybrid approach partially relying on the embedded discrete fracture model(EDFM).This model assumes the region outside the stimulated reservoir volume(SRV)as a single-medium while the SRV region itself is described using a double-medium strategy which can account for thefluid exchange between the matrix and the micro-fractures.The shale gas adsorption,desorption,diffusion,gas slippage effect,fracture stress sensitivity,and capillary imbibition have been considered.The shale gas production,pore pressure distribution and water saturation distribution in the reservoir have been simulated.The influences of hydraulic fracture geometry and nonorthogonal hydraulic fractures on gas production have been determined and discussed accordingly.The simulation results show that the daily gas production has an upward and downward trend due to the presence of a large amount of fracturingfluid in the reservoir around the hydraulic fracture.The smaller the angle between the hydraulic fracture and the wellbore,the faster the daily production of shale gas wells decreases,and the lower the cumulative production.Nonplanar fractures can increase the control volume of hydraulic fractures and improve the production of shale gas wells.展开更多
Background:The assessment of Fontan circuit’sflow is traditionally evaluated by multiple through-plane phase-contrast MRI acquisitions(2Dflow),while recently,a single volumetric 4D-flow MRI acquisition is emerging as a ...Background:The assessment of Fontan circuit’sflow is traditionally evaluated by multiple through-plane phase-contrast MRI acquisitions(2Dflow),while recently,a single volumetric 4D-flow MRI acquisition is emerging as a comprehensive tool for the hemodynamic evaluation in congenital heart diseases.Purpose:To compare 2D and 4D-flow MRI measurements in patients after Fontan palliation and to evaluate parameters affecting potential dis-agreement.Methods:39 patients after Fontan palliation(23 males,age 22±11 years)who underwent cardiac MRI with 2D and 4D-flow MRI acquisition were included in the study.In all patients,bloodflow quantification in the Fontan circuit and aorta by 2Dflow and by 4Dflow MRI acquisition blinding to the 2D results was per-formed.The agreement between 2D and 4D-flow MRI was calculated as the intraclass correlation coefficient(ICC).The mean absolute differences between 4D and 2Dflows were analyzed using linear regression models.Results:4D-flow MRI acquisition time was slightly lower than 2D(7.6±1.8 min vs.9.4±3.3 min,p=0.03).Flow was slightly predominant in the right pulmonary artery(58%of total pulmonaryflow).Conduit/tunnel-pul-monary arteriesflow accounted for 60%of the Fontan circuit.Agreement between 2D and 4D was overall good-to-excellent from ICC:0.81795%CI:0.637–0.907 to 0.93295%CI:0.866–0.965.There was no significant influ-ence of evaluated parameters on the agreement on 4D and 2Dflow.Conclusions:4D-flow MRI represents a valid tool in Fontan’sflow quantification.Further larger studies are needed to confirm our results and to evaluate the impact of advanced 4D-flow MRI parameters on the prognostic stratification in patients after Fontan palliation.展开更多
A three-dimensional multicomponent multiphase lattice Boltzmann model(LBM)is established to model the coupled two-phase and reactive transport phenomena in the cathode electrode of proton exchange membrane fuel cells....A three-dimensional multicomponent multiphase lattice Boltzmann model(LBM)is established to model the coupled two-phase and reactive transport phenomena in the cathode electrode of proton exchange membrane fuel cells.The gas diff usion layer(GDL)and microporous layer(MPL)are stochastically reconstructed with the inside dynamic distribution of oxygen and liquid water resolved,and the catalyst layer is simplifi ed as a superthin layer to address the electrochemical reaction,which provides a clear description of the fl ooding eff ect on mass transport and performance.Diff erent kinds of electrodes are reconstructed to determine the optimum porosity and structure design of the GDL and MPL by comparing the transport resistance and per-formance under the fl ooding condition.The simulation results show that gradient porosity GDL helps to increase the reactive area and average concentration under fl ooding.The presence of the MPL ensures the oxygen transport space and reaction area because liquid water cannot transport through micropores.Moreover,the MPL helps in the uniform distribution of oxygen for an effi cient in-plane transport capacity.Crack and perforation structures can accelerate the water transport in the assembly.The systematic perforation design yields the best performance under fl ooding by separating the transport of liquid water and oxygen.展开更多
Redox-flow batteries(RFBs)are a promising energy storage technology with remarkable scalability and safety for storing vast amounts of renewable energy and mitigating outputfluctuations of renewable power grids.We demon...Redox-flow batteries(RFBs)are a promising energy storage technology with remarkable scalability and safety for storing vast amounts of renewable energy and mitigating outputfluctuations of renewable power grids.We demonstrate a neutral pH aqueous RFB using a custom-designed 1’,1’’’,1’’’’’-(benzene-1,3,5-triyltris(methylene))tris(1-(3-(trimethyl ammonio)propyl)-[4’’,4’’’-bipyridine]-1,1’-diium)nonachloride(BTTMPB)as a 3 e-storage anolyte.The custom design with the high polarization in charge density has led to the excellent water solubility of 4.0 M in H_(2)O(321.6 A h L^(-1))and 2.4 M in 2.0 M NaCl(192.9 A h L^(-1)).The density functional theory(DFT)calculations and electrochemical experiments have shown 3 e-storage response of BTTMPB with a diffusion coefficient of 3.1×10^(-6)cm^(2) s^(-1)and rate con-stant of 1.6×10^(-2)cm s^(-1) for thefirst reduction process.The synthesized anolyte was paired with(Ferrocenylmethyl)trimethylammonium chloride(FcNCl)as catholyte enabling a 0.92 V aqueous RFB with 125.9 W h L^(-1)theoretical energy density.The aqueous RFB has an excellent cycling performance from 10-30 m A cm^(-2),energy efficiency up to 80%,capacity retention of 99.96%per cycle at 20 m A cm^(-2),and a high demonstrated energy density of 29.1 W h L^(-1).展开更多
Development of electrodes with high electrocatalytic activity and stability is essential for solving problems that still restrict the extensive application of vanadium redox flow batteries(VRFBs).Here,we designed a no...Development of electrodes with high electrocatalytic activity and stability is essential for solving problems that still restrict the extensive application of vanadium redox flow batteries(VRFBs).Here,we designed a novel negative electrode with superior electrocatalytic activity by tailoring nitrogen functional groups,such as newly formed nitro and pyridinic-N transformed to pyridonic-N,from the prenitrogen-doped electrode.It was experimentally confirmed that an electrode with pyridonic-N and nitro fuctional groups(tailored nitrogen-doped graphite felt,TNGF) has superior electrocatalytic acivity with enhanced electron and mass transfer.Density functional theory calulations demonstrated the pyridonic-N and nitro functional groups promoted the adsorption,charge transfer,and bond formation with the vanadium species,which is consistent with expermental results.In addition,the V2+/V3+redox reaction mechanism on pyridonic-N and nitro functional groups was estabilised based on density functional theory(DFT) results.When TNGF was applied to a VRFB,it enabled enhanced-electrolyte utilization and energy efficiencies(EE) of 57.9% and 64.6%,respectively,at a current density of 250 mA cm^(-2).These results are 18.6% and 8.9% higher than those of VRFB with electrode containing graphitic-N and pyridinicN groups.Interestingly,TNGF-based VRFB still operated with an EE of 59% at a high current density of300 mA cm^(-2).The TNGF-based VRFB exhibited stable cycling performance without noticeable decay of EE over 450 charge-discharge cycles at a current density of 250 mA cm^(-2).The results of this study suggest that introducing pyridonic-N and nitro groups on the electrode is effective for improving the electrochemical performance of VRFBs.展开更多
With the growing global environmental awareness,the development of renewable and green materials has gained increased worldwide interest to substitute conventional materials and are favorable for sustainable economic ...With the growing global environmental awareness,the development of renewable and green materials has gained increased worldwide interest to substitute conventional materials and are favorable for sustainable economic development.This paper proposed a novel eco-friendly sound absorbing structure(NSAS)liner for noise reduction in elevator shafts.The base layer integrated with the shaft walls is a damping gypsum mortarboard,and a rock wool board and a perforated cement mortarboard are used to compose the NSAS.Based on the acoustic impedance theory of porous materials and perforated panels,the sound absorption theory of the NSAS was proposed;the parameter effects of the rock wool board(flow resistivity,porosity,structure factor)and perforated panel(perforated rates,thickness,density,perforated diameter)on NSAS absorption were discussed theoretically for absorption improvement,and experiments were also conducted.Numerical results showed that the perforation rate,the thickness of the perforated plate,and the porosity,flow resistance,and volume density of the rock wool board played a key issue in the absorption performances of the NSAS.Experiments verified the accuracy of the proposed theoretical model.Wideband sound absorption performance of the NSAS at frequencies between 500–1600 Hz was achieved in both numerical analysis and experiments,and the sound absorption coefficient was improved to 0.72 around 1000 Hz after parameter adjustments.The NSAS proposed in this paper can also be made of other renewable materials with preferable structure strength and still has the potential to broaden the absorption bandwidth.It can provide a reference for controlling the elevator shaft noise.展开更多
The vehicular ad hoc network(VANET)is an emerging network tech-nology that has gained popularity because to its low cost,flexibility,and seamless services.Software defined networking(SDN)technology plays a critical role...The vehicular ad hoc network(VANET)is an emerging network tech-nology that has gained popularity because to its low cost,flexibility,and seamless services.Software defined networking(SDN)technology plays a critical role in network administration in the future generation of VANET withfifth generation(5G)networks.Regardless of the benefits of VANET,energy economy and traffic control are significant architectural challenges.Accurate and real-time trafficflow prediction(TFP)becomes critical for managing traffic effectively in the VANET.SDN controllers are a critical issue in VANET,which has garnered much interest in recent years.With this objective,this study develops the SDNTFP-C technique,a revolutionary SDN controller-based real-time trafficflow forecasting technique for clustered VANETs.The proposed SDNTFP-C technique combines the SDN controller’s scalability,flexibility,and adaptability with deep learning(DL)mod-els.Additionally,a novel arithmetic optimization-based clustering technique(AOCA)is developed to cluster automobiles in a VANET.The TFP procedure is then performed using a hybrid convolutional neural network model with atten-tion-based bidirectional long short-term memory(HCNN-ABLSTM).To optimise the performance of the HCNN-ABLSTM model,the dingo optimization techni-que was used to tune the hyperparameters(DOA).The experimental results ana-lysis reveals that the suggested method outperforms other current techniques on a variety of evaluation metrics.展开更多
The two-stage hybridflow shop problem under setup times is addressed in this paper.This problem is NP-Hard.on the other hand,the studied problem is modeling different real-life applications especially in manufacturing...The two-stage hybridflow shop problem under setup times is addressed in this paper.This problem is NP-Hard.on the other hand,the studied problem is modeling different real-life applications especially in manufacturing and high performance-computing.Tackling this kind of problem requires the development of adapted algorithms.In this context,a metaheuristic using the genetic algorithm and three heuristics are proposed in this paper.These approximate solutions are using the optimal solution of the parallel machines under release and delivery times.Indeed,these solutions are iterative procedures focusing each time on a particular stage where a parallel machines problem is called to be solved.The general solution is then a concatenation of all the solutions in each stage.In addition,three lower bounds based on the relaxation method are provided.These lower bounds present a means to evaluate the efficiency of the developed algorithms throughout the measurement of the relative gap.An experimental result is discussed to evaluate the performance of the developed algorithms.In total,8960 instances are implemented and tested to show the results given by the proposed lower bounds and heuristics.Several indicators are given to compare between algorithms.The results illustrated in this paper show the performance of the developed algorithms in terms of gap and running time.展开更多
文摘In this paper, the problem of finding exact solutions to the magnetohydrodynamic(MHD) equations in the presence of incompressible mass flows with helical symmetry is considered. For ideal flows, a similarity reduction method is used to obtain exact solutions for several MHD flows with nonlinear variable Mach number. For resistive flows parallel to a magnetic field, the governing equilibrium equation is derived. The MHD equilibrium state of a helically symmetric incompressible flow is governed by a second-order elliptic partial differential equation(PDE) for the helical magnetic flux function. Exact solutions for the latter equation are obtained. Also, the equilibrium equations of a gravitating plasma with incompressible flow are derived.
文摘Scientific workflows have gained the emerging attention in sophisti-cated large-scale scientific problem-solving environments.The pay-per-use model of cloud,its scalability and dynamic deployment enables it suited for executing scientific workflow applications.Since the cloud is not a utopian environment,failures are inevitable that may result in experiencingfluctuations in the delivered performance.Though a single task failure occurs in workflow based applications,due to its task dependency nature,the reliability of the overall system will be affected drastically.Hence rather than reactive fault-tolerant approaches,proactive measures are vital in scientific workflows.This work puts forth an attempt to con-centrate on the exploration issue of structuring a nature inspired metaheuristics-Intelligent Water Drops Algorithm(IWDA)combined with an efficient machine learning approach-Support Vector Regression(SVR)for task failure prognostica-tion which facilitates proactive fault-tolerance in the scheduling of scientific workflow applications.The failure prediction models in this study have been implemented through SVR-based machine learning approaches and the precision accuracy of prediction is optimized by IWDA and several performance metrics were evaluated on various benchmark workflows.The experimental results prove that the proposed proactive fault-tolerant approach performs better compared with the other existing techniques.
文摘OWS(OGC Web Service)为空间数据共享提供了可行的方法,但如何在浩瀚的互联网上快速、准确地查询到符合用户需要的OWS是一件比较困难的事情。在对Web搜索方法进行深入理解的基础上,提出一种基于全文检索搜索引擎搭建OWS索引服务的思路,并采用Google实现了OWS索引服务中心的原型系统,该系统可以为互联网用户提供OWS搜索服务。
文摘随着网络技术的不断成熟,许多新技术成功地运用到GIS系统的客户端数据展现当中,而最引人注目的技术就是A-JAX;另一方面,开放地理信息系统联盟(OGC)开发了一系列基于Web服务技术的地理空间数据互操作协议OGC Web Services(OWS),其中的Web Map Services(WMS)已经广泛地应用于GIS领域。本文首先对于AJAX技术和OWS规范进行基础性的阐述,之后将详细介绍一个结合AJAX技术和OWS规范构造的GIS系统—ACT-GIS。
基金Project supported by the National Natural Science Foundation of China(Nos.11772162 and11472140)the Inner Mongolia Autonomous Region Grassland Talent of China(No.12000-12102013)the Natural Science Foundation of Inner Mongolia Autonomous Region of China(No.2016MS0106)
文摘Considering the influence of the streaming potential and electroviscous effects, the analytical solutions for electromagnetohydrodynamic (EMHD) flows in parallel plate microchannels are obtained. The electrolyte solutions in the microchannels are taken as generalized Maxwell fluids, and slip boundary conditions are adopted. To accurately analyze the EMHD flow characteristics, the variation trends of the electroviscous effects with the corresponding parameters must be understood. The results show that the electroviscous effects increase with the increase in the relaxation time De, the slip coefficient , and the wall zeta potential 0. However, the increase in the inverse of the electrical double-layer (EDL) thickness K, the electrical oscillating Reynolds number Re, and the ionic P'eclet number Pe can decrease the electroviscous effects. We also demonstrate that the electroviscous effect on the EMHD flows of generalized Maxwell fluids is larger than that of Newtonian fluids. This work will be useful in designing EMHD flows in parallel plate microchannels.
基金supported by the Scientific and Innovative Action Plan of Shanghai(21N31900800)Shanghai Rising-Star Program(23QB1403500)+4 种基金the Shanghai Sailing Program(20YF1443000)Shanghai Science and Technology Commission,the Belt and Road Project(20310750500)Talent Project of SAAS(2023-2025)Runup Plan of SAAS(ZP22211)the SAAS Program for Excellent Research Team(2022(B-16))。
文摘Traditional transgenic detection methods require high test conditions and struggle to be both sensitive and efficient.In this study,a one-tube dual recombinase polymerase amplification(RPA)reaction system for CP4-EPSPS and Cry1Ab/Ac was proposed and combined with a lateral flow immunochromatographic assay,named“Dual-RPA-LFD”,to visualize the dual detection of genetically modified(GM)crops.In which,the herbicide tolerance gene CP4-EPSPS and the insect resistance gene Cry1Ab/Ac were selected as targets taking into account the current status of the most widespread application of insect resistance and herbicide tolerance traits and their stacked traits.Gradient diluted plasmids,transgenic standards,and actual samples were used as templates to conduct sensitivity,specificity,and practicality assays,respectively.The constructed method achieved the visual detection of plasmid at levels as low as 100 copies,demonstrating its high sensitivity.In addition,good applicability to transgenic samples was observed,with no cross-interference between two test lines and no influence from other genes.In conclusion,this strategy achieved the expected purpose of simultaneous detection of the two popular targets in GM crops within 20 min at 37°C in a rapid,equipmentfree field manner,providing a new alternative for rapid screening for transgenic assays in the field.
基金the Guangdong Basic and Applied Basic Research Foundation(grant number:2019A1515011819,2021B1515120004)National Natural Science Foundation of China(22005207)Open Research Fund of Songshan Lake Materials Laboratory(2021SLABFN04).
文摘Non-flow aqueous zinc-bromine batteries without auxiliary components(e.g.,pumps,pipes,storage tanks)and ion-selective membranes represent a cost-effective and promising technology for large-scale energy storage.Unfortunately,they generally suffer from serious diffusion and shuttle of polybromide(Br^(-),Br^(3-))due to the weak physical adsorption between soluble polybromide and host carbon materials,which results in low energy efficiency and poor cycling stability.Here,we develop a novel self-capture organic bromine material(1,10-bis[3-(trimethylammonio)propyl]-4,4'-bipyridinium bromine,NVBr4)to successfully realize reversible solid complexation of bromide components for stable non-flow zinc-bromine battery applications.The quaternary ammonium groups(NV^(4+)ions)can effectively capture the soluble polybromide species based on strong chemical interaction and realize reversible solid complexation confined within the porous electrodes,which transforms the conventional“liquid-liquid”conversion of soluble bromide components into“liquid-solid”model and effectively suppresses the shuttle effect.Thereby,the developed non-flow zinc-bromide battery provides an outstanding voltage platform at 1.7 V with a notable specific capacity of 325 mAh g^(-1)NVBr4(1 A g^(-1)),excellent rate capability(200 mAh g^(-1)NVBr4 at 20 A g^(-1)),outstanding energy density of 469.6 Wh kg^(-1)and super-stable cycle life(20,000 cycles with 100%Coulombic efficiency),which outperforms most of reported zinc-halogen batteries.Further mechanism analysis and DFT calculations demonstrate that the chemical interaction of quaternary ammonium groups and bromide species is the main reason for suppressing the shuttle effect.The developed strategy can be extended to other halogen batteries to obtain stable charge storage.
文摘Hydrodynamics characterization in terms offlow regime behavior is a crucial task to enhance the design of bubble column reactors and scaling up related methodologies.This review presents recent studies on the typicalflow regimes established in bubble columns.Some effort is also provided to introduce relevant definitions pertaining to thisfield,namely,that of“void fraction”and related(local,chordal,cross-sectional and volumetric)variants.Experimental studies involving different parameters that affect design and operating conditions are also discussed in detail.In the second part of the review,the attention is shifted to cases with internals of various types(perfo-rated plates,baffles,vibrating helical springs,mixers,and heat exchanger tubes)immersed in the bubble columns.It is shown that the presence of these elements has a limited influence on the global column hydrodynamics.However,they can make the homogeneousflow regime more stable in terms of transition gas velocity and transi-tion holdup value.The last section is used to highlight gaps which have not beenfilled yet and future directions of investigation.
基金supported by Natural Science Foundation of Anhui Higher Education Institution of China(2023AH051318).
文摘Ensuring a stable power output from renewable energy sources,such as wind and solar energy,depends on the development of large-scale and long-duration energy storage devices.Zinc–bromine fl ow batteries(ZBFBs)have emerged as cost-eff ective and high-energy-density solutions,replacing expensive all-vanadium fl ow batteries.However,uneven Zn deposition during charging results in the formation of problematic Zn dendrites,leading to mass transport polarization and self-discharge.Stable Zn plating and stripping are essential for the successful operation of high-areal-capacity ZBFBs.In this study,we successfully synthesized nitrogen and oxygen co-doped functional carbon felt(NOCF4)electrode through the oxidative polymerization of dopamine,followed by calcination under ambient conditions.The NOCF4 electrode eff ectively facilitates effi cient“shuttle deposition”of Zn during charging,signifi cantly enhancing the areal capacity of the electrode.Remarkably,ZBFBs utilizing NOCF4 as the anode material exhibited stable cycling performance for 40 cycles(approximately 240 h)at an areal capacity of 60 mA h/cm^(2).Even at a high areal capacity of 130 mA h/cm^(2),an impressive energy effi ciency of 76.98%was achieved.These fi ndings provide a promising pathway for the development of high-areal-capacity ZBFBs for advanced energy storage systems.
基金support from China Postdoctoral Science Foundation(Grant No.2021M690960)China CSC abroad studying fellowship.R.C.thanks the KIST Europe basic research funding“new electrolytes for redox flow batteries”and the partial financial support from the CMBlu Energy AG.Y.Z.thanks to the support received from the National Natural Science Foundation of China(Grant No.22002009)the Natural Science Foundation of Hunan Province(Grant No.2021JJ40565).
文摘Aqueous redox-active organic materials-base electrolytes are sustainable alternatives to vanadium-based electrolyte for redoxflow batteries(RFBs)due to the advantages of high ionic conductivity,environmentally benign,safety and low cost.However,the underexplored redox properties of organic materials and the narrow thermodynamic electrolysis window of water(1.23 V)hinder their wide applications.Therefore,seeking suitable organic redox couples and aqueous electrolytes with a high output voltage is highly suggested for advancing the aqueous organic RFBs.In this work,the functionalized phenazine and nitroxyl radical with electron-donating and electron-withdrawing group exhibit redox potential of-0.88 V and 0.78 V vs.Ag,respectively,in“water-in-ionic liquid”supporting electrolytes.Raman spectra reveal that the activity of water is largely suppressed in“water-in-ionic liquid”due to the enhanced hydrogen bond interactions between ionic liquid and water,enabling an electrochemical stability window above 3 V.“Water-in-ionic liquid”supporting electrolytes help to shift redox potential of nitroxyl radical and enable the redox activity of functionalized phenazine.The assembled aqueous RFB allows a theoretical cell voltage of 1.66 V and shows a practical discharge voltage of 1.5 V in the“water-in-ionic liquid”electrolytes.Meanwhile,capacity retention of 99.91%per cycle is achieved over 500 charge/discharge cycles.A power density of 112 mW cm^(-2) is obtained at a current density of 30 mA cm^(-2).This work highlights the importance of rationally combining supporting electrolytes and organic molecules to achieve high-voltage aqueous RFBs.
基金supported by the National Natural Science Foundation of China(Grant Nos.U19A2043 and 52174033)Natural Science Foundation of Sichuan Province(NSFSC)(No.2022NSFSC0971)the Science and Technology Cooperation Project of the CNPC-SWPU Innovation Alliance.
文摘The gas-water two-phaseflow occurring as a result of fracturingfluidflowback phenomena is known to impact significantly the productivity of shale gas well.In this work,this two-phaseflow has been simulated in the framework of a hybrid approach partially relying on the embedded discrete fracture model(EDFM).This model assumes the region outside the stimulated reservoir volume(SRV)as a single-medium while the SRV region itself is described using a double-medium strategy which can account for thefluid exchange between the matrix and the micro-fractures.The shale gas adsorption,desorption,diffusion,gas slippage effect,fracture stress sensitivity,and capillary imbibition have been considered.The shale gas production,pore pressure distribution and water saturation distribution in the reservoir have been simulated.The influences of hydraulic fracture geometry and nonorthogonal hydraulic fractures on gas production have been determined and discussed accordingly.The simulation results show that the daily gas production has an upward and downward trend due to the presence of a large amount of fracturingfluid in the reservoir around the hydraulic fracture.The smaller the angle between the hydraulic fracture and the wellbore,the faster the daily production of shale gas wells decreases,and the lower the cumulative production.Nonplanar fractures can increase the control volume of hydraulic fractures and improve the production of shale gas wells.
基金The Institutional Review Board and Regional Committee(CEAVNO)approved the study(Study No.13756 approved in September 2018).
文摘Background:The assessment of Fontan circuit’sflow is traditionally evaluated by multiple through-plane phase-contrast MRI acquisitions(2Dflow),while recently,a single volumetric 4D-flow MRI acquisition is emerging as a comprehensive tool for the hemodynamic evaluation in congenital heart diseases.Purpose:To compare 2D and 4D-flow MRI measurements in patients after Fontan palliation and to evaluate parameters affecting potential dis-agreement.Methods:39 patients after Fontan palliation(23 males,age 22±11 years)who underwent cardiac MRI with 2D and 4D-flow MRI acquisition were included in the study.In all patients,bloodflow quantification in the Fontan circuit and aorta by 2Dflow and by 4Dflow MRI acquisition blinding to the 2D results was per-formed.The agreement between 2D and 4D-flow MRI was calculated as the intraclass correlation coefficient(ICC).The mean absolute differences between 4D and 2Dflows were analyzed using linear regression models.Results:4D-flow MRI acquisition time was slightly lower than 2D(7.6±1.8 min vs.9.4±3.3 min,p=0.03).Flow was slightly predominant in the right pulmonary artery(58%of total pulmonaryflow).Conduit/tunnel-pul-monary arteriesflow accounted for 60%of the Fontan circuit.Agreement between 2D and 4D was overall good-to-excellent from ICC:0.81795%CI:0.637–0.907 to 0.93295%CI:0.866–0.965.There was no significant influ-ence of evaluated parameters on the agreement on 4D and 2Dflow.Conclusions:4D-flow MRI represents a valid tool in Fontan’sflow quantification.Further larger studies are needed to confirm our results and to evaluate the impact of advanced 4D-flow MRI parameters on the prognostic stratification in patients after Fontan palliation.
基金by the National Natural Science Foundation of China(No.51976138)National Engineering Laboratory for Mobile Source Emission Control Technology(No.NELMS2019A10).
文摘A three-dimensional multicomponent multiphase lattice Boltzmann model(LBM)is established to model the coupled two-phase and reactive transport phenomena in the cathode electrode of proton exchange membrane fuel cells.The gas diff usion layer(GDL)and microporous layer(MPL)are stochastically reconstructed with the inside dynamic distribution of oxygen and liquid water resolved,and the catalyst layer is simplifi ed as a superthin layer to address the electrochemical reaction,which provides a clear description of the fl ooding eff ect on mass transport and performance.Diff erent kinds of electrodes are reconstructed to determine the optimum porosity and structure design of the GDL and MPL by comparing the transport resistance and per-formance under the fl ooding condition.The simulation results show that gradient porosity GDL helps to increase the reactive area and average concentration under fl ooding.The presence of the MPL ensures the oxygen transport space and reaction area because liquid water cannot transport through micropores.Moreover,the MPL helps in the uniform distribution of oxygen for an effi cient in-plane transport capacity.Crack and perforation structures can accelerate the water transport in the assembly.The systematic perforation design yields the best performance under fl ooding by separating the transport of liquid water and oxygen.
基金the Department of Science and Technology(DST),Ministry of Science and Technology,Government of India,for sponsoring this study under project no.DST/TMD/MES/2k18/02CSIR,Gov.of India,for the Senior Research Fellowship。
文摘Redox-flow batteries(RFBs)are a promising energy storage technology with remarkable scalability and safety for storing vast amounts of renewable energy and mitigating outputfluctuations of renewable power grids.We demonstrate a neutral pH aqueous RFB using a custom-designed 1’,1’’’,1’’’’’-(benzene-1,3,5-triyltris(methylene))tris(1-(3-(trimethyl ammonio)propyl)-[4’’,4’’’-bipyridine]-1,1’-diium)nonachloride(BTTMPB)as a 3 e-storage anolyte.The custom design with the high polarization in charge density has led to the excellent water solubility of 4.0 M in H_(2)O(321.6 A h L^(-1))and 2.4 M in 2.0 M NaCl(192.9 A h L^(-1)).The density functional theory(DFT)calculations and electrochemical experiments have shown 3 e-storage response of BTTMPB with a diffusion coefficient of 3.1×10^(-6)cm^(2) s^(-1)and rate con-stant of 1.6×10^(-2)cm s^(-1) for thefirst reduction process.The synthesized anolyte was paired with(Ferrocenylmethyl)trimethylammonium chloride(FcNCl)as catholyte enabling a 0.92 V aqueous RFB with 125.9 W h L^(-1)theoretical energy density.The aqueous RFB has an excellent cycling performance from 10-30 m A cm^(-2),energy efficiency up to 80%,capacity retention of 99.96%per cycle at 20 m A cm^(-2),and a high demonstrated energy density of 29.1 W h L^(-1).
基金financially supported by the Research Program from Korea Institute of Industrial Technology(EM220011)the Technology Innovation Program(20020229,Development of technology for manufacturing catalysts and electrode parts by use of low contents precious metals of rare metals) funded by the Ministry of Trade,Industry&Energy(MOTIE,Korea)+2 种基金the National Research Foundation of Korea(NRF) grant funded by the Korea government(MSIT)(2022R1F1A1072569)supported by the Basic Science Research Program through the National Research Foundation of Korea(NRF) funded by the Ministry of Science,ICT & Future Planning(NRF2020R1C1C1010493)“Regional Innovation Strategy(RIS)” through the National Research Foundation of Korea(NRF) funded by the Ministry of Education(MOE)(2021RIS-004)。
文摘Development of electrodes with high electrocatalytic activity and stability is essential for solving problems that still restrict the extensive application of vanadium redox flow batteries(VRFBs).Here,we designed a novel negative electrode with superior electrocatalytic activity by tailoring nitrogen functional groups,such as newly formed nitro and pyridinic-N transformed to pyridonic-N,from the prenitrogen-doped electrode.It was experimentally confirmed that an electrode with pyridonic-N and nitro fuctional groups(tailored nitrogen-doped graphite felt,TNGF) has superior electrocatalytic acivity with enhanced electron and mass transfer.Density functional theory calulations demonstrated the pyridonic-N and nitro functional groups promoted the adsorption,charge transfer,and bond formation with the vanadium species,which is consistent with expermental results.In addition,the V2+/V3+redox reaction mechanism on pyridonic-N and nitro functional groups was estabilised based on density functional theory(DFT) results.When TNGF was applied to a VRFB,it enabled enhanced-electrolyte utilization and energy efficiencies(EE) of 57.9% and 64.6%,respectively,at a current density of 250 mA cm^(-2).These results are 18.6% and 8.9% higher than those of VRFB with electrode containing graphitic-N and pyridinicN groups.Interestingly,TNGF-based VRFB still operated with an EE of 59% at a high current density of300 mA cm^(-2).The TNGF-based VRFB exhibited stable cycling performance without noticeable decay of EE over 450 charge-discharge cycles at a current density of 250 mA cm^(-2).The results of this study suggest that introducing pyridonic-N and nitro groups on the electrode is effective for improving the electrochemical performance of VRFBs.
基金supported by Opening Foundation of Key Laboratory of New Technology for Construction of Cities in Mountain Area,Ministry of Education,China(LNTCCMA-20210104)This work was also supported by the Natural Science Foundation of China(Grant No.51408113)the Natural Science Foundation of Jiangsu Province,China(Grant No.BK20140632).
文摘With the growing global environmental awareness,the development of renewable and green materials has gained increased worldwide interest to substitute conventional materials and are favorable for sustainable economic development.This paper proposed a novel eco-friendly sound absorbing structure(NSAS)liner for noise reduction in elevator shafts.The base layer integrated with the shaft walls is a damping gypsum mortarboard,and a rock wool board and a perforated cement mortarboard are used to compose the NSAS.Based on the acoustic impedance theory of porous materials and perforated panels,the sound absorption theory of the NSAS was proposed;the parameter effects of the rock wool board(flow resistivity,porosity,structure factor)and perforated panel(perforated rates,thickness,density,perforated diameter)on NSAS absorption were discussed theoretically for absorption improvement,and experiments were also conducted.Numerical results showed that the perforation rate,the thickness of the perforated plate,and the porosity,flow resistance,and volume density of the rock wool board played a key issue in the absorption performances of the NSAS.Experiments verified the accuracy of the proposed theoretical model.Wideband sound absorption performance of the NSAS at frequencies between 500–1600 Hz was achieved in both numerical analysis and experiments,and the sound absorption coefficient was improved to 0.72 around 1000 Hz after parameter adjustments.The NSAS proposed in this paper can also be made of other renewable materials with preferable structure strength and still has the potential to broaden the absorption bandwidth.It can provide a reference for controlling the elevator shaft noise.
文摘The vehicular ad hoc network(VANET)is an emerging network tech-nology that has gained popularity because to its low cost,flexibility,and seamless services.Software defined networking(SDN)technology plays a critical role in network administration in the future generation of VANET withfifth generation(5G)networks.Regardless of the benefits of VANET,energy economy and traffic control are significant architectural challenges.Accurate and real-time trafficflow prediction(TFP)becomes critical for managing traffic effectively in the VANET.SDN controllers are a critical issue in VANET,which has garnered much interest in recent years.With this objective,this study develops the SDNTFP-C technique,a revolutionary SDN controller-based real-time trafficflow forecasting technique for clustered VANETs.The proposed SDNTFP-C technique combines the SDN controller’s scalability,flexibility,and adaptability with deep learning(DL)mod-els.Additionally,a novel arithmetic optimization-based clustering technique(AOCA)is developed to cluster automobiles in a VANET.The TFP procedure is then performed using a hybrid convolutional neural network model with atten-tion-based bidirectional long short-term memory(HCNN-ABLSTM).To optimise the performance of the HCNN-ABLSTM model,the dingo optimization techni-que was used to tune the hyperparameters(DOA).The experimental results ana-lysis reveals that the suggested method outperforms other current techniques on a variety of evaluation metrics.
基金The authors would like to thank the Deanship of Scientific Research at Majmaah University for supporting this work under Project Number No.1439-19.
文摘The two-stage hybridflow shop problem under setup times is addressed in this paper.This problem is NP-Hard.on the other hand,the studied problem is modeling different real-life applications especially in manufacturing and high performance-computing.Tackling this kind of problem requires the development of adapted algorithms.In this context,a metaheuristic using the genetic algorithm and three heuristics are proposed in this paper.These approximate solutions are using the optimal solution of the parallel machines under release and delivery times.Indeed,these solutions are iterative procedures focusing each time on a particular stage where a parallel machines problem is called to be solved.The general solution is then a concatenation of all the solutions in each stage.In addition,three lower bounds based on the relaxation method are provided.These lower bounds present a means to evaluate the efficiency of the developed algorithms throughout the measurement of the relative gap.An experimental result is discussed to evaluate the performance of the developed algorithms.In total,8960 instances are implemented and tested to show the results given by the proposed lower bounds and heuristics.Several indicators are given to compare between algorithms.The results illustrated in this paper show the performance of the developed algorithms in terms of gap and running time.