Fluid-structure interaction(FSI) is a class of mechanics-related problems with mutual dependence between the fluid and structure parts and it is observable nearly everywhere,in natural phenomena to many engineering sy...Fluid-structure interaction(FSI) is a class of mechanics-related problems with mutual dependence between the fluid and structure parts and it is observable nearly everywhere,in natural phenomena to many engineering systems.The primary challenges in developing numerical models with conventional grid-based methods are the inherent nonlinearity and timedependent nature of FSI,together with possible large deformations and moving interfaces.Smoothed particle hydrodynamics(SPH) method is a truly Lagrangian and meshfree particle method that conveniently treats large deformations and naturally captures rapidly moving interfaces and free surfaces.Since its invention,the SPH method has been widely applied to study different problems in engineering and sciences,including FSI problems.This article presents a review of the recent developments in SPH based modeling techniques for solving FSI-related problems.The basic concepts of SPH along with conventional and higher order particle approximation schemes are first introduced.Then,the implementation of FSI in a pure SPH framework and the hybrid approaches of SPH with other grid-based or particle-based methods are discussed.The SPH models of FSI problems with rigid,elastic and flexible structures,with granular materials,and with extremely intensive loadings are demonstrated.Some discussions on several key techniques in SPH including the balance of accuracy,stability and efficiency,the treatment of material interface,the coupling of SPH with other methods,and the particle regularization and adaptive particle resolution are provided as concluding marks.展开更多
Although the deep learning technology has shown great power in solving the complex tasks, these neural network models are large and redundant as a matter of fact, which makes these networks difficult to be placed in e...Although the deep learning technology has shown great power in solving the complex tasks, these neural network models are large and redundant as a matter of fact, which makes these networks difficult to be placed in embedded devices with limited memory and computing resources. In order to compress the neural network to a slimmer and smaller one, the multi-grained network pruning framework is proposed in this paper. In our framework, the pruning process was divided into the filter-level pruning and the weight-level pruning. In the process of the filter-level pruning, the importance of the filter was measured by the entropy of the activation tensor of the filter. In the other process, the dynamic recoverable pruning method was adopted to prune the weights deeply. Different from these popular pruning methods, the weight-level pruning is also taken into account based on the employment of the filter-level pruning to achieve more effectively pruning. The proposed approach is validated on two representative CNN models - AlexNet and VGG16, pre-trained on ILSVRC12. Experimental results show that AlexNet and VGG16 network models are compressed 19.75 and 22.53 respectively by this approach, which are 2.05 and 5.89 higher than the classical approaches of dynamic Network Surgery and ThiNet.展开更多
In linear optics,photons are scatered in a network through passive optical elements including beam spliters and phase shifers,leading to many intriguing applications in physics,such as Mach–Zehnder interferometry,the...In linear optics,photons are scatered in a network through passive optical elements including beam spliters and phase shifers,leading to many intriguing applications in physics,such as Mach–Zehnder interferometry,the Hong–Ou–Mandel effect,and tests of fundamental quantum mechanics.Here we present the fundamental limit in the transition amplitudes of bosons,applicable to all physical linear optical networks.Apart from boson sampling,this transition bound results in many other interesting applications,including behaviors of Bose–Einstein condensates(BEC)in optical networks,counterparts of Hong–Ou–Mandel effects for multiple photons,and approximating permanents of matrices.In addition,this general bound implies the existence of a polynomial-time randomized algorithm for estimating the transition amplitudes of bosons,which represents a solution to an open problem raised by Aaronson and Hance(Quantum Inf Comput 2012;14:541–59).Consequently,this bound implies that computational decision problems encoded in linear optics,prepared and detected in the Fock basis,can be solved efciently by classical computers within additive errors.Furthermore,our result also leads to a classical sampling algorithm that can be applied to calculate the many-body wave functions and the S-matrix of bosonic particles.展开更多
The goal of efficient computation is to determine reasonable computing cost in polynomial time by using data structure of instance, and analyze the computing cost of satisfactory solution which can meet user’s requir...The goal of efficient computation is to determine reasonable computing cost in polynomial time by using data structure of instance, and analyze the computing cost of satisfactory solution which can meet user’s requirements. When faced with NP-hard problem, we usually assess computational performance in the worst case. Polynomial algorithm cannot handle with NP-hard problem, so we research on NP-hard problem from efficient computation point of view. The work is intended to fill the blank of computational complexity theory.We focus on the cluster structure of instance data of aircraft range problem. By studying the partition and complexity measurement of cluster, we establish a connection between the aircraft range problem and N-vehicle exploration problem, and construct the efficient computation mechanism for aircraft range problem. The last examples show that the effect is significant when we use efficient computation mechanism on aircraft range problem. Decision makers can calculate the computing cost before actually computing.展开更多
The pebble-bed reactor is one of the most promising designs for the nuclear energy industry. In this paper, a discrete element method-computational fluid dynamics (DEM-CFD) approach that includes thermal conduction, r...The pebble-bed reactor is one of the most promising designs for the nuclear energy industry. In this paper, a discrete element method-computational fluid dynamics (DEM-CFD) approach that includes thermal conduction, radiation, and natural convection mechanisms was proposed to simulate the thermal-fluid phenomena after the failure of forced circulation cooling system in a pebble-bed core. The whole large-scale packed bed was created using the DEM technique, and the calculated radial porosity of the bed was validated with empirical correlations reported by researchers. To reduce computational costs, a segment of the bed was extracted, which served as a good representative of the large-scale packed bed for CFD calculation. The temperature distributions simulated with two different fluids in this DEM-CFD approach were in good agreement with SANA experimental data. The influence of the natural convection mechanism on heat transfer must be taken into account for coolants with strong convective capacity. The proposed DEM-CFD methodology offers a computationally efficient and widely applied method for understanding the heat transfer process in a pebble-bed core. The method can also be easily extended to assess the passive safety features of newly designed fluoride- salt-cooled pebble-bed reactors.展开更多
In order to verify the effectiveness and superiority of the dynamic hybrid RANS/LES(DHRL)model,the flow around a cylinder with sinusoidal fluctuating velocity at the inlet was used as the test case.The latest computat...In order to verify the effectiveness and superiority of the dynamic hybrid RANS/LES(DHRL)model,the flow around a cylinder with sinusoidal fluctuating velocity at the inlet was used as the test case.The latest computational fluid dynamics(CFD)model can flexibly choose any existing large-eddy simulation(LES)method combined with RANS method to calculate the flow field.In addition,the DLES model and DDES model are selected as typical representatives of the turbulence model to compare the capture ability of the flow field mechanism.The internal flow field including the y+value,velocity distribution,turbulent kinetic energy and vortex structures is comprehensively analyzed.Finally,the results show that the new model has enough sensitivity to capture the information of the flow field and has more consistent velocity distribution with the experimental value,which shows its potential in practical engineering applications to some extent.展开更多
Compared to the traditional one-by-one method,a new high-efficiency method is used to characterize large numbers of regulations varying samples.Accordingly,bump-shaped electrodes are designed using the computational f...Compared to the traditional one-by-one method,a new high-efficiency method is used to characterize large numbers of regulations varying samples.Accordingly,bump-shaped electrodes are designed using the computational fluid dynamics model,and the effect of the height and placement of these electrodes is discussed.The experimental feasibility is certified by weight loss measurement.Results indicate that flow velocities of different bump-shaped electrode surfaces are significant differences.Thus,each surface can be analyzed independently;the thickness loss of each electrode surface is consistent with that using one-by-one method,which can effectively improve the experimental efficiency 12 times.展开更多
Compared with open propellers, the impeller of a tunnel thruster is more vulnerable to cavitation and structural vibration problems because the impeller is typically subject to severe non-uniformity of inflow produced...Compared with open propellers, the impeller of a tunnel thruster is more vulnerable to cavitation and structural vibration problems because the impeller is typically subject to severe non-uniformity of inflow produced by the blunt gearbox. Model tests and numerical simulations are carried out in the cavitation tunnel of Shanghai Jiao Tong University for a tunnel thruster using a 'flat plate' impeller and a tip-unloaded one. The characteristics of fluctuating pressures on the tunnel wall and the resultant excitation forces are investigated. It is found that although unloading the blade tips of an impeller is effective in reducing the fluctuating pressures in a local tunnel wall area near the tips, the same trend does not apply to the case of the excitation forces. The results show that care should be taken when the experimentally measured fluctuating pressures are utilized as the input to the analysis of structural vibrations.展开更多
The smoothed finite element method (S-FEM) was originated by G R Liu by combining some meshfree techniques with the well-established standard finite element method (FEM). It has a family of models carefully designed w...The smoothed finite element method (S-FEM) was originated by G R Liu by combining some meshfree techniques with the well-established standard finite element method (FEM). It has a family of models carefully designed with innovative types of smoothing domains. These models are found having a number of important and theoretically profound properties. This article first provides a concise and easy-to-follow presentation of key formulations used in the S-FEM. A number of important properties and unique features of S-FEM models are discussed in detail, including 1) theoretically proven softening effects;2) upper-bound solutions;3) accurate solutions and higher convergence rates;4) insensitivity to mesh distortion;5) Jacobian?free;6) volumetric-locking-free;and most importantly 7) working well with triangular and tetrahedral meshes that can be automatically generated. The S-FEM is thus ideal for automation in computations and adaptive analyses, and hence has profound impact on Al-assisted modeling and simulation. Most importantly, one can now purposely design an S-FEM model to obtain solutions with special properties as wish, meaning that S-FEM offers a framework for design numerical models with desired properties. This novel concept of numerical model demand may drastically change the landscape of modeling and simulation. Future directions of research are also provided.展开更多
Gas-solid two-phase flow in a circulating fluidized bed (CFB) is affected by operating conditions (e.g., superficial gas velocity, solids inventory), material properties and geometric factors, such as the entry and ex...Gas-solid two-phase flow in a circulating fluidized bed (CFB) is affected by operating conditions (e.g., superficial gas velocity, solids inventory), material properties and geometric factors, such as the entry and exit configuration. In particular, the suspension section, which is located between the riser bottom and the solids recycle inlet, affects the hydrodynamics in the riser significantly. However, the suspension section has received less attention compared with other geometric factors. Most computational fluid dynamics (CFD) simulations, especially two-dimensional simulations do not take this factor into account. We performed three-dimensional, full-loop CFD simulations with a drag coefficient that was determined by the energy-minimization multi-scale model, and investigated the flow behavior of two CFBs with different suspension-section lengths. The simulation resuits revealed that the axial profiles of voidage in the riser with a longer suspension section are more likely S-shaped, whereas those with shorter suspension sections decay exponentially. The dependences of solids flux on solids inventory differ in the two CFBs. A shorter suspension section may result in a smooth transition from dilute to dense transport without intermediate accumulative choki-ng, whereas a Ion ger suspe nsion section may lead to a choking transition. These simulation results are qualitatively consistent with the flow behaviors described in literature.展开更多
Backgrounds Arachidonic acid (AA) metabolic network is activated in the most inflammatory related diseases, and small-molecular drugs targeting AA network are increasingly available. However, side effects of above men...Backgrounds Arachidonic acid (AA) metabolic network is activated in the most inflammatory related diseases, and small-molecular drugs targeting AA network are increasingly available. However, side effects of above mentioned drugs have always been the biggest obstacle.什)-2-( 1 -hydroxy 1-4-oxocycIohexyl) ethyl caffeate (HOEC), a natural product acted as an inhibitor of 5-Iipoxygenase (5-LOX) and 15-LOX in vitro^ exhibited weaker therapeutic effect in high dose than that in low dose to collagen induced arthritis (CIA) rats. In this study, we tried to elucidate the potential regulatory mechanism by using quantitative pharmacology. Methods: First, we generated an experimental data set by monitoring the dynamics of AA metabolites, concentration in A23187 stimulated and different doses of HOEC co-incubated RAW264.7. Then we constructed a dynamic model of A23187-stimulated AA metabolic model to evaluate how a model-based simulation of AA metabolic data assists to find the most suitable treatment dose by predicting the pharmacodynamics of HOEC? Results: Compared to the experimental data, the model could simulate the inhibitory effect of HOEC on 5-LOX and 15-LOX, and reproduced the increase of the metabolic flux in the cyclooxygenase (COX) pathway. However, a concomitant, early-stage of stimulation-related decrease of prostaglandins (PGs) production in HOEC incubated RAW264.7 cells was not simulated in the model. Conclusion-. Using the model, we predict that higher dose of HOEC disrupts the flux balance in COX and LOX of the AA network, and increased COX flux can interfere the curative effects of LOX inhibitor on resolution of inflammation which is crucial for the efficient and safe drug design.展开更多
As the supporting supplier of the main engine plant, the general air filter manufacturers have insufficient technical reserves. The structural optimization of air filter is often based on the bench experiment, which h...As the supporting supplier of the main engine plant, the general air filter manufacturers have insufficient technical reserves. The structural optimization of air filter is often based on the bench experiment, which has high implementation cost and poor performance. In view of this, taking computational fluid dynamics(CFD) as the basic technical means, an optimization design method based on parametric sensitivity combined with equidistant search was proposed. Specifically, the sensitivity of local structure parameters to pressure loss was analyzed by taking local structure of air filter as the object. According to the sensitivity, the method of equidistant search was used to optimize the parameters in order, so as to achieve the goal of overall optimization. After optimization, the pressure loss decreased by 45.13% and the effect was remarkable.展开更多
A combustion model of a large-scale supercritical circulati ng fluidized bed (CFB) boiler was developed for comprehensive computational-fluid-dynamics analysis. The model incorporates gas-solid hydrodynamics, coal com...A combustion model of a large-scale supercritical circulati ng fluidized bed (CFB) boiler was developed for comprehensive computational-fluid-dynamics analysis. The model incorporates gas-solid hydrodynamics, coal combustion, heat transfer on heat exchange surfaces in the furnace, and heat transfer between fumace and working medium in the heat transfer tubes. In simulating the dense and dilute phases in the fumace, the gas-solid hydrodynamics is based on the Euler-Euler model and energy-minimization multiscale drag model. Coal combustion entails evaporation, devolatilization, char combustion, gas homoge neous reaction, and pollutant emission. The coefficient ofheat transfer between gas-solid and the waterwall is estimated using the cluster renewal model, and for radiation, the discrete ordinate model is used. Moreover, thermohydraulic processes in the membrane wall are also in eluded in the heat transfer process. The model was successfully applied in simulations of a 350-MW supercritical CFB boiler. Detailed distributions of solids concentration, oxygen, heat flux, and working medium temperature in the boiler furnace are presented.展开更多
The dispersed phase in multiphase flows can be modeled by the population balance model(PBM).A typical population balance equation(PBE)contains terms for spatial transport,loss/growth and breakage/coalescence source te...The dispersed phase in multiphase flows can be modeled by the population balance model(PBM).A typical population balance equation(PBE)contains terms for spatial transport,loss/growth and breakage/coalescence source terms.The equation is therefore quite complex and difficult to solve analytically or numerically.The quadrature-based moment methods(QBMMs)are a class of methods that solve the PBE by converting the transport equation of the number density function(NDF)into moment transport equations.The unknown source terms are closed by numerical quadrature.Over the years,many QBMMs have been developed for different problems,such as the quadrature method of moments(QMOM),direct quadrature method of moments(DQMOM),extended quadrature method of moments(EQMOM),conditional quadrature method of moments(CQMOM),extended conditional quadrature method of moments(ECQMOM)and hyperbolic quadrature method of moments(Hy QMOM).In this paper,we present a comprehensive algorithm review of these QBMMs.The mathematical equations for spatially homogeneous systems with first-order point processes and second-order point processes are derived in detail.The algorithms are further extended to the inhomogeneous system for multiphase flows,in which the computational fluid dynamics(CFD)can be coupled with the PBE.The physical limitations and the challenging numerical problems of these QBMMs are discussed.Possible solutions are also summarized.展开更多
This study aimed to describe a Computational Fluid Dynamics(CFD) procedure using the ANSYS CFX software 16.1 and Design of Experiments for the determination of volume and extension of explosive atmospheres due to fugi...This study aimed to describe a Computational Fluid Dynamics(CFD) procedure using the ANSYS CFX software 16.1 and Design of Experiments for the determination of volume and extension of explosive atmospheres due to fugitive emissions of flammable gases.The multidimensional statistical sampling technique Latin Hypercube was used, which defined 100 simulations of random methane gas leak conditions.The CFD model proved to be robust in predicting the extension and volume of the explosive atmosphere for orifice diameters from 0.1 to2.5 mm, pressure from 0.1 MPa to 12 MPa and temperatures from 0 ℃ to 400 ℃.It was found that the calculation domain must be parameterized 8 m in length for each millimeter of the diameter of the source of release to ensure the predictions.In order not to lose precision for very small diameters, the mesh was parameterized with 50 elements along the orifice diameter.It was proved that gravity does not influence the extension and volume of the explosive atmosphere at sonic emissions.The deviation from the ideal gas behavior in the reservoir,achieved by applying the Soave–Redlich–Kwong equation of state, also has not significantly influenced the extension and volume of the explosive atmosphere.The results showed that the size of the explosive atmosphere varies directly with the diameter of the source emission and reservoir pressure, and inversely with the temperature of the reservoir.The diameter of the source is the parameter that has the major effect on the extension of the explosive atmosphere, followed by the pressure and lastly the temperature of the reservoir.展开更多
The cathode of biofuel cell reduces molecular oxygen to water using four electrons, an enzyme of multicopper oxidase family, laccase, is contained, though its electron transfer efficiency from the electrode resulted i...The cathode of biofuel cell reduces molecular oxygen to water using four electrons, an enzyme of multicopper oxidase family, laccase, is contained, though its electron transfer efficiency from the electrode resulted in rate determining process. To improve this electron, transfer via mediators, we have investigated several mediator metal complexes between the electrode and laccase, in particular hydrophobic pocket on the surface. We have discussed DFT computational results and selected experimental data of new Mn(III/II) Schiff base complexes having redox active (anthraquinone) ligands and photochromic (azobenzene) ligands about azobenzene moiety at the sole molecular level. Moreover, we carried out computational docking simulation of laccase and complexes considering trans-cis photoisomerization (electronic states) and Weigert effect (molecular orientation to fit better) of azobenzene moiety. Additionally, actual experimental data also presented to indicate the expected merits for mediators.展开更多
Particle accelerators are devices used for research in scientific problems such as high energy and nuclear physics.In a particle accelerator, the shape of particle beam envelope is changed dynamically along the forwar...Particle accelerators are devices used for research in scientific problems such as high energy and nuclear physics.In a particle accelerator, the shape of particle beam envelope is changed dynamically along the forward direction. Thus, this reference direction can be considered as an auxiliary 'time' beam axis. In this paper, the optimal beam matching control problem for a low energy transport system in a charged particle accelerator is considered. The beam matching procedure is formulated as a finite 'time' dynamic optimization problem, in which the Kapchinsky-Vladimirsky(K-V) coupled envelope equations model beam dynamics. The aim is to drive any arbitrary initial beam state to a prescribed target state, as well as to track reference trajectory as closely as possible, through the control of the lens focusing strengths in the beam matching channel. We first apply the control parameterization method to optimize lens focusing strengths, and then combine this with the time-scaling transformation technique to further optimize the drift and lens length in the beam matching channel. The exact gradients of the cost function with respect to the decision parameters are computed explicitly through the state sensitivity-based analysis method. Finally, numerical simulations are illustrated to verify the effectiveness of the proposed approach.展开更多
Ventilation is one of the radon control measures in an underground working environment.However,the dynamics related to the cave mining methods particularly in block/panel cave mines,complicate the design of effective ...Ventilation is one of the radon control measures in an underground working environment.However,the dynamics related to the cave mining methods particularly in block/panel cave mines,complicate the design of effective ventilation system,and implementation.Events such as hang ups(in the drawbells),leakage from old workings,and changes in cave porosity lead to differing response of an existing ventilation designs.However,it is difficult to investigate these conditions at the mine or with a laboratory scale study.Therefore,this study develops a discrete model to investigate the impact of different radon control measures in cave mines using computational fluid dynamics techniques.We considered two ventilation conditions for a fully developed cave:with and without the undercut ventilation.For each of the two conditions,we studied four parameters:airflow distribution through the production drifts,radon distribution through the production drifts,the effect of increasing airflow on radon concentration,and the effect of a cave top negative pressure on radon distribution.The results show that:the undercut ventilation significantly increases the radon concentration in the production drift;the growth of radon concentration through the production drift is nonlinear(oscillating pattern);maintaining a negative pressure on top of the cave is more effective at mitigating radon exposure,when the undercut ventilation is active;and increase in air volume flow rate decreases radon concentration in most regions,however,there might be regions with significant radon accumulation due to pressure variation across the drifts.These findings provide vital information for designing an effective ventilation system and for proactive implementation of radon control measures in cave mines.展开更多
A new unified computational method is proposed for modeling the relationship between the parameters of the high-speed particle-impact texturing process and the final surface morphology of the casting roller. The whole...A new unified computational method is proposed for modeling the relationship between the parameters of the high-speed particle-impact texturing process and the final surface morphology of the casting roller. The whole surface-texturing process is divided into three parts. The first part is the acceleration process of particles inside and outside the nozzle,which can be analyzed using the computational fluid dynamics method to obtain the particle impact velocities. The second part is a simulation of the bombardment process of particles onto the roller surface using the LS-DYNA software as the analysis tool and the results obtained in the first part as input parameters. The last part is the continuously random impact process of particles on the casting roller surface to form a functional surface,which is characterized by a simplified roughness model. Finally,the above three parts are combined to establish a unified computational model,the performance of which is successfully verified in a series of experiments.展开更多
Tropical diseases such as malaria, tuberculosis, trypanosomiasis, and leishmaniasis, account for a large number of deaths annually. Herbs are an excellent source of tropical medicines. Many advancements and discoverie...Tropical diseases such as malaria, tuberculosis, trypanosomiasis, and leishmaniasis, account for a large number of deaths annually. Herbs are an excellent source of tropical medicines. Many advancements and discoveries have taken place in the field of drug discovery but still, a major population of tropical diseases relies on herbal traditional medicine. There are some challenges related to policy implementation, efficacy, resistance and toxicity of tropical medicines. There are many tropical diseases such as such as schistosomiasis, leishmaniasis, African sleeping sickness, filariasis and chagas disease which are neglected because very few pharmaceutical companies have shown their interest in developing therapeutics against these diseases of poor people. There are many benefits associated with herbal medicine such as the cost of production, patient tolerance, large scale availability, efficacy, safety, potency, recyclability, and environment friendly. A large number of natural extracts such as curcumin, artemisinin, morphine, reserpine, and hypericin, are in use for treatment of different tropical diseases for a long time. The current review is to discuss the overview of tropical medicinal herbs, its scope and limitations in the modern drug discovery process.展开更多
基金the National Natural Science Foundation of China (Grant No.51779003)the National Key Research and Development Project of China (Grant No.2018YFB0704000).
文摘Fluid-structure interaction(FSI) is a class of mechanics-related problems with mutual dependence between the fluid and structure parts and it is observable nearly everywhere,in natural phenomena to many engineering systems.The primary challenges in developing numerical models with conventional grid-based methods are the inherent nonlinearity and timedependent nature of FSI,together with possible large deformations and moving interfaces.Smoothed particle hydrodynamics(SPH) method is a truly Lagrangian and meshfree particle method that conveniently treats large deformations and naturally captures rapidly moving interfaces and free surfaces.Since its invention,the SPH method has been widely applied to study different problems in engineering and sciences,including FSI problems.This article presents a review of the recent developments in SPH based modeling techniques for solving FSI-related problems.The basic concepts of SPH along with conventional and higher order particle approximation schemes are first introduced.Then,the implementation of FSI in a pure SPH framework and the hybrid approaches of SPH with other grid-based or particle-based methods are discussed.The SPH models of FSI problems with rigid,elastic and flexible structures,with granular materials,and with extremely intensive loadings are demonstrated.Some discussions on several key techniques in SPH including the balance of accuracy,stability and efficiency,the treatment of material interface,the coupling of SPH with other methods,and the particle regularization and adaptive particle resolution are provided as concluding marks.
文摘Although the deep learning technology has shown great power in solving the complex tasks, these neural network models are large and redundant as a matter of fact, which makes these networks difficult to be placed in embedded devices with limited memory and computing resources. In order to compress the neural network to a slimmer and smaller one, the multi-grained network pruning framework is proposed in this paper. In our framework, the pruning process was divided into the filter-level pruning and the weight-level pruning. In the process of the filter-level pruning, the importance of the filter was measured by the entropy of the activation tensor of the filter. In the other process, the dynamic recoverable pruning method was adopted to prune the weights deeply. Different from these popular pruning methods, the weight-level pruning is also taken into account based on the employment of the filter-level pruning to achieve more effectively pruning. The proposed approach is validated on two representative CNN models - AlexNet and VGG16, pre-trained on ILSVRC12. Experimental results show that AlexNet and VGG16 network models are compressed 19.75 and 22.53 respectively by this approach, which are 2.05 and 5.89 higher than the classical approaches of dynamic Network Surgery and ThiNet.
基金M.-H.Y.acknowledges support from the National Natural Science Foundation of China(11875160)the Guangdong Innovative and Entrepreneurial Research Team Program(2016ZT06D348)+2 种基金the Natural Science Foundation of Guangdong Province(2017B030308003)the Science,Technology and Innovation Commission of Shenzhen Municipality(ZDSYS20170303165926217,JCYJ20170412152620376,JCYJ20170817105046702)J.H.acknowledges support from the Basic Science Research Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Education,Science and Technology(NRF-2015R1A6A 3A04059773).
文摘In linear optics,photons are scatered in a network through passive optical elements including beam spliters and phase shifers,leading to many intriguing applications in physics,such as Mach–Zehnder interferometry,the Hong–Ou–Mandel effect,and tests of fundamental quantum mechanics.Here we present the fundamental limit in the transition amplitudes of bosons,applicable to all physical linear optical networks.Apart from boson sampling,this transition bound results in many other interesting applications,including behaviors of Bose–Einstein condensates(BEC)in optical networks,counterparts of Hong–Ou–Mandel effects for multiple photons,and approximating permanents of matrices.In addition,this general bound implies the existence of a polynomial-time randomized algorithm for estimating the transition amplitudes of bosons,which represents a solution to an open problem raised by Aaronson and Hance(Quantum Inf Comput 2012;14:541–59).Consequently,this bound implies that computational decision problems encoded in linear optics,prepared and detected in the Fock basis,can be solved efciently by classical computers within additive errors.Furthermore,our result also leads to a classical sampling algorithm that can be applied to calculate the many-body wave functions and the S-matrix of bosonic particles.
基金Supported by Key Laboratory of Management, Decision and Information Systems, Chinese Academy of Science.
文摘The goal of efficient computation is to determine reasonable computing cost in polynomial time by using data structure of instance, and analyze the computing cost of satisfactory solution which can meet user’s requirements. When faced with NP-hard problem, we usually assess computational performance in the worst case. Polynomial algorithm cannot handle with NP-hard problem, so we research on NP-hard problem from efficient computation point of view. The work is intended to fill the blank of computational complexity theory.We focus on the cluster structure of instance data of aircraft range problem. By studying the partition and complexity measurement of cluster, we establish a connection between the aircraft range problem and N-vehicle exploration problem, and construct the efficient computation mechanism for aircraft range problem. The last examples show that the effect is significant when we use efficient computation mechanism on aircraft range problem. Decision makers can calculate the computing cost before actually computing.
基金the Chinese TMSR Strategic PioneerScience and Technology Project (No. XDA02010000)theFrontier Science Key Program of the Chinese Academy of Sciences(No. QYZDY-SSW-JSC016).
文摘The pebble-bed reactor is one of the most promising designs for the nuclear energy industry. In this paper, a discrete element method-computational fluid dynamics (DEM-CFD) approach that includes thermal conduction, radiation, and natural convection mechanisms was proposed to simulate the thermal-fluid phenomena after the failure of forced circulation cooling system in a pebble-bed core. The whole large-scale packed bed was created using the DEM technique, and the calculated radial porosity of the bed was validated with empirical correlations reported by researchers. To reduce computational costs, a segment of the bed was extracted, which served as a good representative of the large-scale packed bed for CFD calculation. The temperature distributions simulated with two different fluids in this DEM-CFD approach were in good agreement with SANA experimental data. The influence of the natural convection mechanism on heat transfer must be taken into account for coolants with strong convective capacity. The proposed DEM-CFD methodology offers a computationally efficient and widely applied method for understanding the heat transfer process in a pebble-bed core. The method can also be easily extended to assess the passive safety features of newly designed fluoride- salt-cooled pebble-bed reactors.
基金the Open Fund of Key Laboratory of Road Construction Technology and Equipment of Chang'an University,Ministry of Education(310825171104)the Advanced Manufacturing Projects of Government and University Co-construction Program Funded by Jilin Province(SXGJSF2017-2).
文摘In order to verify the effectiveness and superiority of the dynamic hybrid RANS/LES(DHRL)model,the flow around a cylinder with sinusoidal fluctuating velocity at the inlet was used as the test case.The latest computational fluid dynamics(CFD)model can flexibly choose any existing large-eddy simulation(LES)method combined with RANS method to calculate the flow field.In addition,the DLES model and DDES model are selected as typical representatives of the turbulence model to compare the capture ability of the flow field mechanism.The internal flow field including the y+value,velocity distribution,turbulent kinetic energy and vortex structures is comprehensively analyzed.Finally,the results show that the new model has enough sensitivity to capture the information of the flow field and has more consistent velocity distribution with the experimental value,which shows its potential in practical engineering applications to some extent.
基金the National Key Research and Development Program of China (No.2017YFB0702203)the National Natural Science Foundation of China (No.U1460202)+1 种基金the National program for the Young Top-notch Professionalsthe Fundamental Research Funds for the Central Universities (No.N170205002).
文摘Compared to the traditional one-by-one method,a new high-efficiency method is used to characterize large numbers of regulations varying samples.Accordingly,bump-shaped electrodes are designed using the computational fluid dynamics model,and the effect of the height and placement of these electrodes is discussed.The experimental feasibility is certified by weight loss measurement.Results indicate that flow velocities of different bump-shaped electrode surfaces are significant differences.Thus,each surface can be analyzed independently;the thickness loss of each electrode surface is consistent with that using one-by-one method,which can effectively improve the experimental efficiency 12 times.
文摘Compared with open propellers, the impeller of a tunnel thruster is more vulnerable to cavitation and structural vibration problems because the impeller is typically subject to severe non-uniformity of inflow produced by the blunt gearbox. Model tests and numerical simulations are carried out in the cavitation tunnel of Shanghai Jiao Tong University for a tunnel thruster using a 'flat plate' impeller and a tip-unloaded one. The characteristics of fluctuating pressures on the tunnel wall and the resultant excitation forces are investigated. It is found that although unloading the blade tips of an impeller is effective in reducing the fluctuating pressures in a local tunnel wall area near the tips, the same trend does not apply to the case of the excitation forces. The results show that care should be taken when the experimentally measured fluctuating pressures are utilized as the input to the analysis of structural vibrations.
文摘The smoothed finite element method (S-FEM) was originated by G R Liu by combining some meshfree techniques with the well-established standard finite element method (FEM). It has a family of models carefully designed with innovative types of smoothing domains. These models are found having a number of important and theoretically profound properties. This article first provides a concise and easy-to-follow presentation of key formulations used in the S-FEM. A number of important properties and unique features of S-FEM models are discussed in detail, including 1) theoretically proven softening effects;2) upper-bound solutions;3) accurate solutions and higher convergence rates;4) insensitivity to mesh distortion;5) Jacobian?free;6) volumetric-locking-free;and most importantly 7) working well with triangular and tetrahedral meshes that can be automatically generated. The S-FEM is thus ideal for automation in computations and adaptive analyses, and hence has profound impact on Al-assisted modeling and simulation. Most importantly, one can now purposely design an S-FEM model to obtain solutions with special properties as wish, meaning that S-FEM offers a framework for design numerical models with desired properties. This novel concept of numerical model demand may drastically change the landscape of modeling and simulation. Future directions of research are also provided.
基金financially by the National Natural Science Foundation of China under Grant Nos. 21625605 and 21821005the Science and Technology project of AQSIQGrant No. 2016QK196.
文摘Gas-solid two-phase flow in a circulating fluidized bed (CFB) is affected by operating conditions (e.g., superficial gas velocity, solids inventory), material properties and geometric factors, such as the entry and exit configuration. In particular, the suspension section, which is located between the riser bottom and the solids recycle inlet, affects the hydrodynamics in the riser significantly. However, the suspension section has received less attention compared with other geometric factors. Most computational fluid dynamics (CFD) simulations, especially two-dimensional simulations do not take this factor into account. We performed three-dimensional, full-loop CFD simulations with a drag coefficient that was determined by the energy-minimization multi-scale model, and investigated the flow behavior of two CFBs with different suspension-section lengths. The simulation resuits revealed that the axial profiles of voidage in the riser with a longer suspension section are more likely S-shaped, whereas those with shorter suspension sections decay exponentially. The dependences of solids flux on solids inventory differ in the two CFBs. A shorter suspension section may result in a smooth transition from dilute to dense transport without intermediate accumulative choki-ng, whereas a Ion ger suspe nsion section may lead to a choking transition. These simulation results are qualitatively consistent with the flow behaviors described in literature.
基金the National Key Research and Development Program (No. 2016YFA0502304)Special Program for Applied Research on Super Computation of the NSFC-Guangdong Joint Fund (the second phase, No.U150l501)the National Natural Science Foundation of China (No. 21173076).
文摘Backgrounds Arachidonic acid (AA) metabolic network is activated in the most inflammatory related diseases, and small-molecular drugs targeting AA network are increasingly available. However, side effects of above mentioned drugs have always been the biggest obstacle.什)-2-( 1 -hydroxy 1-4-oxocycIohexyl) ethyl caffeate (HOEC), a natural product acted as an inhibitor of 5-Iipoxygenase (5-LOX) and 15-LOX in vitro^ exhibited weaker therapeutic effect in high dose than that in low dose to collagen induced arthritis (CIA) rats. In this study, we tried to elucidate the potential regulatory mechanism by using quantitative pharmacology. Methods: First, we generated an experimental data set by monitoring the dynamics of AA metabolites, concentration in A23187 stimulated and different doses of HOEC co-incubated RAW264.7. Then we constructed a dynamic model of A23187-stimulated AA metabolic model to evaluate how a model-based simulation of AA metabolic data assists to find the most suitable treatment dose by predicting the pharmacodynamics of HOEC? Results: Compared to the experimental data, the model could simulate the inhibitory effect of HOEC on 5-LOX and 15-LOX, and reproduced the increase of the metabolic flux in the cyclooxygenase (COX) pathway. However, a concomitant, early-stage of stimulation-related decrease of prostaglandins (PGs) production in HOEC incubated RAW264.7 cells was not simulated in the model. Conclusion-. Using the model, we predict that higher dose of HOEC disrupts the flux balance in COX and LOX of the AA network, and increased COX flux can interfere the curative effects of LOX inhibitor on resolution of inflammation which is crucial for the efficient and safe drug design.
基金Supported by the General Plan Projects of Science and Technology of Jiangxi Provincial Department of Education(GJJ151161,GJJ180976)the Plan Projects of Science and Technology of Jiangxi Provincial Department of Science and Technology(20161BBE50053)the Foundation of the Center of Collaboration and Innovation(18XTKFYB03).
文摘As the supporting supplier of the main engine plant, the general air filter manufacturers have insufficient technical reserves. The structural optimization of air filter is often based on the bench experiment, which has high implementation cost and poor performance. In view of this, taking computational fluid dynamics(CFD) as the basic technical means, an optimization design method based on parametric sensitivity combined with equidistant search was proposed. Specifically, the sensitivity of local structure parameters to pressure loss was analyzed by taking local structure of air filter as the object. According to the sensitivity, the method of equidistant search was used to optimize the parameters in order, so as to achieve the goal of overall optimization. After optimization, the pressure loss decreased by 45.13% and the effect was remarkable.
基金the National Key Research & Development Program of China (No. 2016YFB0600202-2).
文摘A combustion model of a large-scale supercritical circulati ng fluidized bed (CFB) boiler was developed for comprehensive computational-fluid-dynamics analysis. The model incorporates gas-solid hydrodynamics, coal combustion, heat transfer on heat exchange surfaces in the furnace, and heat transfer between fumace and working medium in the heat transfer tubes. In simulating the dense and dilute phases in the fumace, the gas-solid hydrodynamics is based on the Euler-Euler model and energy-minimization multiscale drag model. Coal combustion entails evaporation, devolatilization, char combustion, gas homoge neous reaction, and pollutant emission. The coefficient ofheat transfer between gas-solid and the waterwall is estimated using the cluster renewal model, and for radiation, the discrete ordinate model is used. Moreover, thermohydraulic processes in the membrane wall are also in eluded in the heat transfer process. The model was successfully applied in simulations of a 350-MW supercritical CFB boiler. Detailed distributions of solids concentration, oxygen, heat flux, and working medium temperature in the boiler furnace are presented.
文摘The dispersed phase in multiphase flows can be modeled by the population balance model(PBM).A typical population balance equation(PBE)contains terms for spatial transport,loss/growth and breakage/coalescence source terms.The equation is therefore quite complex and difficult to solve analytically or numerically.The quadrature-based moment methods(QBMMs)are a class of methods that solve the PBE by converting the transport equation of the number density function(NDF)into moment transport equations.The unknown source terms are closed by numerical quadrature.Over the years,many QBMMs have been developed for different problems,such as the quadrature method of moments(QMOM),direct quadrature method of moments(DQMOM),extended quadrature method of moments(EQMOM),conditional quadrature method of moments(CQMOM),extended conditional quadrature method of moments(ECQMOM)and hyperbolic quadrature method of moments(Hy QMOM).In this paper,we present a comprehensive algorithm review of these QBMMs.The mathematical equations for spatially homogeneous systems with first-order point processes and second-order point processes are derived in detail.The algorithms are further extended to the inhomogeneous system for multiphase flows,in which the computational fluid dynamics(CFD)can be coupled with the PBE.The physical limitations and the challenging numerical problems of these QBMMs are discussed.Possible solutions are also summarized.
基金Petrobras (0050.0093154.14.9)–Petróleo Brasileiro S.A.for the financial and technical support.
文摘This study aimed to describe a Computational Fluid Dynamics(CFD) procedure using the ANSYS CFX software 16.1 and Design of Experiments for the determination of volume and extension of explosive atmospheres due to fugitive emissions of flammable gases.The multidimensional statistical sampling technique Latin Hypercube was used, which defined 100 simulations of random methane gas leak conditions.The CFD model proved to be robust in predicting the extension and volume of the explosive atmosphere for orifice diameters from 0.1 to2.5 mm, pressure from 0.1 MPa to 12 MPa and temperatures from 0 ℃ to 400 ℃.It was found that the calculation domain must be parameterized 8 m in length for each millimeter of the diameter of the source of release to ensure the predictions.In order not to lose precision for very small diameters, the mesh was parameterized with 50 elements along the orifice diameter.It was proved that gravity does not influence the extension and volume of the explosive atmosphere at sonic emissions.The deviation from the ideal gas behavior in the reservoir,achieved by applying the Soave–Redlich–Kwong equation of state, also has not significantly influenced the extension and volume of the explosive atmosphere.The results showed that the size of the explosive atmosphere varies directly with the diameter of the source emission and reservoir pressure, and inversely with the temperature of the reservoir.The diameter of the source is the parameter that has the major effect on the extension of the explosive atmosphere, followed by the pressure and lastly the temperature of the reservoir.
文摘The cathode of biofuel cell reduces molecular oxygen to water using four electrons, an enzyme of multicopper oxidase family, laccase, is contained, though its electron transfer efficiency from the electrode resulted in rate determining process. To improve this electron, transfer via mediators, we have investigated several mediator metal complexes between the electrode and laccase, in particular hydrophobic pocket on the surface. We have discussed DFT computational results and selected experimental data of new Mn(III/II) Schiff base complexes having redox active (anthraquinone) ligands and photochromic (azobenzene) ligands about azobenzene moiety at the sole molecular level. Moreover, we carried out computational docking simulation of laccase and complexes considering trans-cis photoisomerization (electronic states) and Weigert effect (molecular orientation to fit better) of azobenzene moiety. Additionally, actual experimental data also presented to indicate the expected merits for mediators.
基金supported by the National Natural Science Foundation of China(61703114,61673126,61703217,U1701261)the Science and Technology Plan Project of Guangdong(2014B090907010,2015B010131014).
文摘Particle accelerators are devices used for research in scientific problems such as high energy and nuclear physics.In a particle accelerator, the shape of particle beam envelope is changed dynamically along the forward direction. Thus, this reference direction can be considered as an auxiliary 'time' beam axis. In this paper, the optimal beam matching control problem for a low energy transport system in a charged particle accelerator is considered. The beam matching procedure is formulated as a finite 'time' dynamic optimization problem, in which the Kapchinsky-Vladimirsky(K-V) coupled envelope equations model beam dynamics. The aim is to drive any arbitrary initial beam state to a prescribed target state, as well as to track reference trajectory as closely as possible, through the control of the lens focusing strengths in the beam matching channel. We first apply the control parameterization method to optimize lens focusing strengths, and then combine this with the time-scaling transformation technique to further optimize the drift and lens length in the beam matching channel. The exact gradients of the cost function with respect to the decision parameters are computed explicitly through the state sensitivity-based analysis method. Finally, numerical simulations are illustrated to verify the effectiveness of the proposed approach.
基金the National Institute for Occupational Safety and Health(NIOSH)(No.200-2014-59613)for conducting this research.
文摘Ventilation is one of the radon control measures in an underground working environment.However,the dynamics related to the cave mining methods particularly in block/panel cave mines,complicate the design of effective ventilation system,and implementation.Events such as hang ups(in the drawbells),leakage from old workings,and changes in cave porosity lead to differing response of an existing ventilation designs.However,it is difficult to investigate these conditions at the mine or with a laboratory scale study.Therefore,this study develops a discrete model to investigate the impact of different radon control measures in cave mines using computational fluid dynamics techniques.We considered two ventilation conditions for a fully developed cave:with and without the undercut ventilation.For each of the two conditions,we studied four parameters:airflow distribution through the production drifts,radon distribution through the production drifts,the effect of increasing airflow on radon concentration,and the effect of a cave top negative pressure on radon distribution.The results show that:the undercut ventilation significantly increases the radon concentration in the production drift;the growth of radon concentration through the production drift is nonlinear(oscillating pattern);maintaining a negative pressure on top of the cave is more effective at mitigating radon exposure,when the undercut ventilation is active;and increase in air volume flow rate decreases radon concentration in most regions,however,there might be regions with significant radon accumulation due to pressure variation across the drifts.These findings provide vital information for designing an effective ventilation system and for proactive implementation of radon control measures in cave mines.
文摘A new unified computational method is proposed for modeling the relationship between the parameters of the high-speed particle-impact texturing process and the final surface morphology of the casting roller. The whole surface-texturing process is divided into three parts. The first part is the acceleration process of particles inside and outside the nozzle,which can be analyzed using the computational fluid dynamics method to obtain the particle impact velocities. The second part is a simulation of the bombardment process of particles onto the roller surface using the LS-DYNA software as the analysis tool and the results obtained in the first part as input parameters. The last part is the continuously random impact process of particles on the casting roller surface to form a functional surface,which is characterized by a simplified roughness model. Finally,the above three parts are combined to establish a unified computational model,the performance of which is successfully verified in a series of experiments.
文摘Tropical diseases such as malaria, tuberculosis, trypanosomiasis, and leishmaniasis, account for a large number of deaths annually. Herbs are an excellent source of tropical medicines. Many advancements and discoveries have taken place in the field of drug discovery but still, a major population of tropical diseases relies on herbal traditional medicine. There are some challenges related to policy implementation, efficacy, resistance and toxicity of tropical medicines. There are many tropical diseases such as such as schistosomiasis, leishmaniasis, African sleeping sickness, filariasis and chagas disease which are neglected because very few pharmaceutical companies have shown their interest in developing therapeutics against these diseases of poor people. There are many benefits associated with herbal medicine such as the cost of production, patient tolerance, large scale availability, efficacy, safety, potency, recyclability, and environment friendly. A large number of natural extracts such as curcumin, artemisinin, morphine, reserpine, and hypericin, are in use for treatment of different tropical diseases for a long time. The current review is to discuss the overview of tropical medicinal herbs, its scope and limitations in the modern drug discovery process.