Researches have indicated that impinging droplets can be entrapped as liquid in the ice matrix and the temperature of accreting ice surface is below the freezing point. When liquid entrapment by ice matrix happens, th...Researches have indicated that impinging droplets can be entrapped as liquid in the ice matrix and the temperature of accreting ice surface is below the freezing point. When liquid entrapment by ice matrix happens, this kind of ice is called spongy ice. A new spongy icing model for the ice accretion problem on airfoil or aircraft has been developed to account for entrapped liquid within accreted ice and to improve the determination of the surface temperature when enter- ing clouds with supercooled droplets. Different with conventional icing model, this model identifies icing conditions in four regimes： rime, spongy without water film, spongy with water film and glaze. By using the Eulerian method based on two-phase flow theory, the impinging droplet flow was investigated numerically. The accuracy of the Eulerian method for computing the water collection efficiency was assessed, and icing shapes and surface temperature distributions predicted with this spongy icing model agree with experimental results well.展开更多
Ice particles could form under the continuous impingement of incoming supercooled droplets in icing conditions,which will change the surface roughness to enhance the further heat and mass transfer during icing process...Ice particles could form under the continuous impingement of incoming supercooled droplets in icing conditions,which will change the surface roughness to enhance the further heat and mass transfer during icing process.A fixed-grid porous enthalpy method based on the improved Discrete Phase Model(DPM)and Volume of Fluid(VOF)integrated algorithm is developed to solve the multiphase heat transfer problem to give more detailed demonstration of the formation of initial ice roughness.The algorithms to determine the criterion of transformation from DPM to VOF and the allocation of source items during transformation are improved to the general DPM-VOF algorithm.Two verification cases,namely two glycerine-solution droplets impact and single droplet freeze,are conducted to verify the accuracy and reliability of the enthalpy-DPMVOF method,where the simulation results match well with experiment phenomena.Ice roughness on a NACA0012 airfoil is precisely captured and the effects on convective heat transfer characteristics are preliminarily revealed.The results illustrate that the enthalpy-DPM-VOF method could successfully capture the characteristics of motion and the phase change process of droplet,as well as balance the calculation accuracy and efficiency.展开更多
The Polar Regions are rich in natural resources but experience an extremely cold climate.The surfaces of offshore platforms operating in the Polar Regions are prone to icing.To develop solutions to this problem of sur...The Polar Regions are rich in natural resources but experience an extremely cold climate.The surfaces of offshore platforms operating in the Polar Regions are prone to icing.To develop solutions to this problem of surface icing,the influence of both the liquid water concentration of the surrounding atmosphere and the average water droplet diameter on the formation of ice on two major structural components of offshore platforms was analyzed using a combination of Fluent and FENSAP-ICE.Results showed that at a wind speed of 7 m/s,as the concentration of liquid water in the air increases from 0.05 to 0.25 g/m3,the amount and thickness of the icing on the surfaces of the two structural components increase linearly.At a wind speed of 7 m/s and when the size of the average water droplet diameter is 20–30(30–35)μm,as the average water droplet diameter increases,the amount and thickness of the icing on the surfaces of the two structural components increase(decrease)gradually.展开更多
The paper analyzes the environments confronted with academic libraries and the evolving characteristics of Shanghai Jiao Tong University that give shape to the conception and implementation of an IC2Culture Exploring ...The paper analyzes the environments confronted with academic libraries and the evolving characteristics of Shanghai Jiao Tong University that give shape to the conception and implementation of an IC2Culture Exploring Project. This innovative model of SJTU Library operation is not only in concert with the strategic goals of SJTU but also with two other conspicuous developmental trends in the larger academic library circle;namely, 1) a trend toward the deepening of library service support in academic arena on the one hand and 2) the trend of diversifying library outreach services on the other hand.Based on our first-hand involvement in all phases and aspects of this project and its subsequent review and analysis undertakings, this paper expatiates upon the IC2Culture Exploring Project of SJTU Library in terms of its vision, its specific mission objectives, its program design, its unique characteristics, its launching process, its salient case studies, its initial results and its strategies for a sustainable development in the future.展开更多
We have proved that any 3-dimensional dynamical system of ordinary differentialequations(in short, 3D ODE)With time-independent invariants can be rewritten asHaniltonian systems with respect to generalized Poisson bra...We have proved that any 3-dimensional dynamical system of ordinary differentialequations(in short, 3D ODE)With time-independent invariants can be rewritten asHaniltonian systems with respect to generalized Poisson brackets and theHamiltonians are these invariants. As an example,we discuss the Kermack-Mckendrick modelfor epidemics in detail. The results we obtained are generalizatioof those obtained by Y. Nutku.展开更多
In social network applications,individual opinion is often influenced by groups,and most decisions usually reflect the majority’s opinions.This imposes the group influence maximization(GIM) problem that selects k ini...In social network applications,individual opinion is often influenced by groups,and most decisions usually reflect the majority’s opinions.This imposes the group influence maximization(GIM) problem that selects k initial nodes,where each node belongs to multiple groups for a given social network and each group has a weight,to maximize the weight of the eventually activated groups.The GIM problem is apparently NP-hard,given the NP-hardness of the influence maximization(IM) problem that does not consider groups.Focusing on activating groups rather than individuals,this paper proposes the complementary maximum coverage(CMC) algorithm,which greedily and iteratively removes the node with the approximate least group influence until at most k nodes remain.Although the evaluation of the current group influence against each node is only approximate,it nevertheless ensures the success of activating an approximate maximum number of groups.Moreover,we also propose the improved reverse influence sampling(IRIS) algorithm through fine-tuning of the renowned reverse influence sampling algorithm for GIM.Finally,we carry out experiments to evaluate CMC and IRIS,demonstrating that they both outperform the baseline algorithms respective of their average number of activated groups under the independent cascade(IC)model.展开更多
Thermal management is a key issue in the integrated circuit(IC)design.In this paper,the superposition strategy was experimentally validated using a modeling IC device,which was fabricated by laboratory-level microfabr...Thermal management is a key issue in the integrated circuit(IC)design.In this paper,the superposition strategy was experimentally validated using a modeling IC device,which was fabricated by laboratory-level microfabrication technique.Metal thin film resistors on the top of dielectric layer were used to analogize the multiple hot-spots in the modeling IC device.The measured temperature rise with multiple hot-spots agrees well with the predictions given by the superposition calculations.With the help of the superposition strategy,thermal management of IC device can be significantly simplified by decomposing the system into sub-systems and optimizing each part individually.The influence coefficients in the superposition strategy extracted from the experimental measurement offer the IC designers a useful engineering tool to facility the thermal optimization and evaluate the thermal performance of IC devices.展开更多
文摘Researches have indicated that impinging droplets can be entrapped as liquid in the ice matrix and the temperature of accreting ice surface is below the freezing point. When liquid entrapment by ice matrix happens, this kind of ice is called spongy ice. A new spongy icing model for the ice accretion problem on airfoil or aircraft has been developed to account for entrapped liquid within accreted ice and to improve the determination of the surface temperature when enter- ing clouds with supercooled droplets. Different with conventional icing model, this model identifies icing conditions in four regimes： rime, spongy without water film, spongy with water film and glaze. By using the Eulerian method based on two-phase flow theory, the impinging droplet flow was investigated numerically. The accuracy of the Eulerian method for computing the water collection efficiency was assessed, and icing shapes and surface temperature distributions predicted with this spongy icing model agree with experimental results well.
基金supported by the National Natural Science Foundation of China(No.51706244)National Science and Technology Major Projects of China(No.2017-VIII-0003-0114)。
文摘Ice particles could form under the continuous impingement of incoming supercooled droplets in icing conditions,which will change the surface roughness to enhance the further heat and mass transfer during icing process.A fixed-grid porous enthalpy method based on the improved Discrete Phase Model(DPM)and Volume of Fluid(VOF)integrated algorithm is developed to solve the multiphase heat transfer problem to give more detailed demonstration of the formation of initial ice roughness.The algorithms to determine the criterion of transformation from DPM to VOF and the allocation of source items during transformation are improved to the general DPM-VOF algorithm.Two verification cases,namely two glycerine-solution droplets impact and single droplet freeze,are conducted to verify the accuracy and reliability of the enthalpy-DPMVOF method,where the simulation results match well with experiment phenomena.Ice roughness on a NACA0012 airfoil is precisely captured and the effects on convective heat transfer characteristics are preliminarily revealed.The results illustrate that the enthalpy-DPM-VOF method could successfully capture the characteristics of motion and the phase change process of droplet,as well as balance the calculation accuracy and efficiency.
基金the National Natural Science Foundation of China(Grant No.51879125)Jiangsu Provincial Higher Education Natural Science Research Major Project(Grant No.18KJA580003)Jiangsu Province“Six Talents Peak”High-level Talents Support Project(Grant No.2018-KTHY-033).
文摘The Polar Regions are rich in natural resources but experience an extremely cold climate.The surfaces of offshore platforms operating in the Polar Regions are prone to icing.To develop solutions to this problem of surface icing,the influence of both the liquid water concentration of the surrounding atmosphere and the average water droplet diameter on the formation of ice on two major structural components of offshore platforms was analyzed using a combination of Fluent and FENSAP-ICE.Results showed that at a wind speed of 7 m/s,as the concentration of liquid water in the air increases from 0.05 to 0.25 g/m3,the amount and thickness of the icing on the surfaces of the two structural components increase linearly.At a wind speed of 7 m/s and when the size of the average water droplet diameter is 20–30(30–35)μm,as the average water droplet diameter increases,the amount and thickness of the icing on the surfaces of the two structural components increase(decrease)gradually.
文摘The paper analyzes the environments confronted with academic libraries and the evolving characteristics of Shanghai Jiao Tong University that give shape to the conception and implementation of an IC2Culture Exploring Project. This innovative model of SJTU Library operation is not only in concert with the strategic goals of SJTU but also with two other conspicuous developmental trends in the larger academic library circle;namely, 1) a trend toward the deepening of library service support in academic arena on the one hand and 2) the trend of diversifying library outreach services on the other hand.Based on our first-hand involvement in all phases and aspects of this project and its subsequent review and analysis undertakings, this paper expatiates upon the IC2Culture Exploring Project of SJTU Library in terms of its vision, its specific mission objectives, its program design, its unique characteristics, its launching process, its salient case studies, its initial results and its strategies for a sustainable development in the future.
文摘We have proved that any 3-dimensional dynamical system of ordinary differentialequations(in short, 3D ODE)With time-independent invariants can be rewritten asHaniltonian systems with respect to generalized Poisson brackets and theHamiltonians are these invariants. As an example,we discuss the Kermack-Mckendrick modelfor epidemics in detail. The results we obtained are generalizatioof those obtained by Y. Nutku.
基金supported by the Natural Science Foundation of Fujian Province (No. 2020J01845)the Educational Research Project for Young and MiddleAged Teachers of Fujian Provincial Department of Education (No. JAT190613)+1 种基金the National Natural Science Foundation of China (Nos. 61772005 and 92067108)the Outstanding Youth Innovation Team Project for Universities of Shandong Province (No. 2020KJN008)。
文摘In social network applications,individual opinion is often influenced by groups,and most decisions usually reflect the majority’s opinions.This imposes the group influence maximization(GIM) problem that selects k initial nodes,where each node belongs to multiple groups for a given social network and each group has a weight,to maximize the weight of the eventually activated groups.The GIM problem is apparently NP-hard,given the NP-hardness of the influence maximization(IM) problem that does not consider groups.Focusing on activating groups rather than individuals,this paper proposes the complementary maximum coverage(CMC) algorithm,which greedily and iteratively removes the node with the approximate least group influence until at most k nodes remain.Although the evaluation of the current group influence against each node is only approximate,it nevertheless ensures the success of activating an approximate maximum number of groups.Moreover,we also propose the improved reverse influence sampling(IRIS) algorithm through fine-tuning of the renowned reverse influence sampling algorithm for GIM.Finally,we carry out experiments to evaluate CMC and IRIS,demonstrating that they both outperform the baseline algorithms respective of their average number of activated groups under the independent cascade(IC)model.
基金supported by the National Science and Technology Major Project of China(Grant No.2009ZX02038-02)the Doctoral Fund of Ministry of Education of China(Grant No.20130001110006)
文摘Thermal management is a key issue in the integrated circuit(IC)design.In this paper,the superposition strategy was experimentally validated using a modeling IC device,which was fabricated by laboratory-level microfabrication technique.Metal thin film resistors on the top of dielectric layer were used to analogize the multiple hot-spots in the modeling IC device.The measured temperature rise with multiple hot-spots agrees well with the predictions given by the superposition calculations.With the help of the superposition strategy,thermal management of IC device can be significantly simplified by decomposing the system into sub-systems and optimizing each part individually.The influence coefficients in the superposition strategy extracted from the experimental measurement offer the IC designers a useful engineering tool to facility the thermal optimization and evaluate the thermal performance of IC devices.
