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Modelling and Simulation of an Ohmic Heating Process 认领
1
作者 Hongwei Zhang Ahmed Mohamed +1 位作者 Timofei Breikin Martin Howarth 《建模与仿真(英文)》 2021年第1期26-42,共17页
Ohmic Heating (OH) is one of the emerging thermal technologies used in food processing which can produce rapid and uniform heating with close to 100% energy transfer efficiency. Although mathematical </span><... Ohmic Heating (OH) is one of the emerging thermal technologies used in food processing which can produce rapid and uniform heating with close to 100% energy transfer efficiency. Although mathematical </span><span style="font-family:Verdana;">modelling</span><span style="font-family:Verdana;"> for OH processes has been studied by many researchers in recent years, systematic simulations of OH have not been developed for model-based control of the processes. In this paper, </span><span style="font-family:Verdana;">mathematical</span><span style="font-family:Verdana;"> model for a Colinear Ohmic Heater is presented, analyzed, and studied based on the selected configuration. A numerical solution for the mathematical equations has been defined and proposed. MATLAB/Simulink model is hence developed and validated against the available data. Simulation results have shown that </span><span style="font-family:Verdana;">MATLAB</span><span style="font-family:Verdana;">/Simulink model can produce robust outputs at low computational costs with an accuracy of up to 99.6% in comparison to the analytical solution. This model can be used in further studies for analysis of the OH processes and development of advanced controllers. 展开更多
关键词 Ohmic Heating Colinear Ohmic Heater Mathematical Modelling Numerical Solution MATLAB/Simulink Simulations
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Flow Characteristics of Two-Dimensional Supersonic Under-Expanded Coanda-Reattached Jet 认领
2
作者 Tetsuji Ohmura Toshihiko Shakouchi +1 位作者 Shunsuke Fukushima Koichi Tsujimoto 《流量控制、测量及可视化(英文)》 2021年第1期1-14,共14页
<span><span style="font-family:;" "=""><span style="font-family:Verdana;"></span><span style="font-family:Verdana;">When there is a wall near ... <span><span style="font-family:;" "=""><span style="font-family:Verdana;"></span><span style="font-family:Verdana;">When there is a wall near the jet, it deflects and flows while being attached to the wall owing to the Coanda effect. The flow characteristics of the incompressible and two-imensional (2D) Coanda-reattached jets have been considerably explained. However, 2D supersonic under-expanded jets, reattached to side walls, have not been sufficiently investigated. These jets are used in gas-atomization to produce fine metal powder particles of several micrometers to several tens micrometers. In this case, the supersonic under-expanded jets are issued from an annular nozzle, which is set around a vertically in</span><span style="font-family:Verdana;">stalled circular nozzle for molten metal. The jet flow at the center</span><span style="font-family:Verdana;"> cross</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">-</span></span></span><span><span><span style="font-family:;" "=""><span style="font-family:Verdana;">section of the annular jet resembles a 2D Coanda-reattached jet that deflects and attaches on the central axis. In this study, the flow characteristics of a supersonic under-expanded Coanda air jet from a 2D nozzle that reattaches to an offset side wall are elucidated through experiment and numerical analysis. For numerical analysis, we show how much it can express experimental results. The effects of supply pressure </span><i><span style="font-family:Verdana;">P</span><span style="font-family:Verdana;"><sub></sub></span><span style="font-family:Verdana;"></span></i><sub><span style="font-family:Verdana;">0</span><span style="font-family:Verdana;"></span></sub></span><span style="font-family:Verdana;"></span><span style="font-family:Verdana;"> on the flow characteristics such as the flow pattern, size of shock cell, reattachment distance, and velocity and pressure distributions, etc. are examined. The flow pattern was visualiz 展开更多
关键词 Supersonic Flow Under-Expanded Jet Coanda Reattached Jet Flow Visualization Gas-Atomization Experimental Analysis Numerical Analysis
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Mathematical Study of Medicine Propagation in Biological Tissue and Some of Its Applications 认领
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作者 N. G. Gulko I. T. Selezov R. I. Volinsky 《应用数学与应用物理(英文)》 2021年第1期127-132,共6页
The paper deals with the problem of the distribution of the medicine (enzyme) in the damaged biological tissue where the reaction enzyme—substrat takes place. The biological problem is reduced to a singular degenerat... The paper deals with the problem of the distribution of the medicine (enzyme) in the damaged biological tissue where the reaction enzyme—substrat takes place. The biological problem is reduced to a singular degenerate initial-boundary value problem for two coupled ordinary differential equations. Analytical solution of the singular degenerated IBV-problem was obtained by power series. The solution demonstrates the real situation and found suitable to depict the degeneration of singular system, caused by low concentration of the enzyme. 展开更多
关键词 ENZYME Substrate Reaction Analytical Solution Numerical Solution Singular Degeneration Initial Boundary Value Problem
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Melting Time Prediction Model for Induction Furnace Melting Using Specific Thermal Consumption from Material Charge Approach 认领
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作者 Onigbajumo Adetunji Seidu Saliu Ojo +1 位作者 Akinlabi Oyetunji Newton Itua 《矿物质和材料特性和工程(英文)》 2021年第1期61-74,共14页
A system-level evaluation was used to analyze the induction furnace operation and process system in this study. This paper presents an investigation into the relationship between the instantaneous chemical composition... A system-level evaluation was used to analyze the induction furnace operation and process system in this study. This paper presents an investigation into the relationship between the instantaneous chemical composition of a molten bath and its energy consumption in steelmaking. This was evaluated using numerical modelling to solve for the estimated melting time prediction for the induction furnace operation. This work provides an insight into the lowering of energy consumption and estimated production time in steelmaking using material charge balancing approach. Enthalpy computation was implemented to develop an energy consumption model for the molten metal using a specific charge composition approach. Computational simulation program engine (CastMELT) was also developed in Java programming language with a MySQL database server for seamless specific charge composition analysis and testing. The model performance was established using real-time production data from a cast iron-based foundry with a 1 and 2-ton induction furnace capacity and a medium carbon-based foundry with a 10- and 15-ton induction furnace capacity. Using parameter fitting techniques on the measured operational data of the induction furnaces at different periods of melting, the results from the model predictions and real-time melting showed good correlation between 81% - 95%. A further analysis that compared the relationship between the mass composition of a current molten bath and melting, time showed that energy consumption can be reduced with effective material balancing and controlled charge. Melting time was obtained as a function of the elemental charge composition of the molten bath in relation to the overall scrap material charge. This validates the approach taken by this research using material charge and thermodynamic of melting to optimize and better control melting operation in foundry and reduce traditional waste during iron and steel making. 展开更多
关键词 Charge Calculation Mass and Energy Balance Melting Time Optimization Induction Furnace Numerical Model Iron and Steelmaking CastMELT
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Dynamic response analysis of train-induced vibration impact on the Probhutaratna pagoda in Beijing 认领
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作者 Li Minghang Ma Meng +2 位作者 Cao Zhonglei Xia Qian Liu Weining 《地震工程与工程振动:英文版》 SCIE EI 2021年第1期223-243,共21页
Train-induced vibration exhibits a potential dynamic impact on historic buildings and especially on those with high historical and cultural value.Under the long-term reciprocating load of train vibrations,structural f... Train-induced vibration exhibits a potential dynamic impact on historic buildings and especially on those with high historical and cultural value.Under the long-term reciprocating load of train vibrations,structural fatigue damage can occur,and thus,a significant problem involves effectively evaluating and mitigating vibration impact on historic buildings while developing a rail transit system.In the present study,train-induced vibration impact and dynamic behavior of Probhutaratna pagoda in the suburb of Beijing,which has a history of approximately 1000 years,was investigated.To examine the dynamic behavior of the Probhutaratna pagoda and determine the weakest position in its architectural damage under train loads,its dynamic characteristics were measured.The free vibration modes were identified based on the dynamic measurement results.Subsequently,a finite element(FE)model of the Probhutaratna pagoda was constructed and the models and train-induced structural responses were compared with measured results.Finally,the structural dynamic responses to moving train loads were analyzed in detail.The results indicate the following conclusions.(1)The dominant frequency of the ambient vibration is below 4 Hz,and the dominant frequency of the train-induced vibration is between 8 and 16 Hz.(2)The first,second,and third order natural frequencies are 1,3.25,and 6 Hz,respectively,in the west-east direction,and are 1,3.25,and 6.25 Hz,respectively,in the north-south direction.(3)The two weakest locations(A and B)of the Probhutaratna pagoda are observed at the spire bottom and west gate of the first floor.At location A,the maximum principal stress reached 243.6 N/m^2 and the corresponding maximum tensile strain reached 3.74×10^-7. 展开更多
关键词 historic building vibration measurement numerical simulation train-induced vibration modal identification
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Benchmarking of two three-dimensional numerical models in time/space domain to predict railway-induced ground vibrations 认领
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作者 Jesus Fernandez-Ruiz Luis E.Medina Rodriguez +1 位作者 Pedro Alves Costa Margarita Martinez-Diaz 《地震工程与工程振动:英文版》 SCIE EI 2021年第1期245-256,共12页
In the last 30 years,the scientific community has developed and proposed different models and numerical approaches for the study of vibrations induced by railway traffic.Most of them are formulated in the frequency/wa... In the last 30 years,the scientific community has developed and proposed different models and numerical approaches for the study of vibrations induced by railway traffic.Most of them are formulated in the frequency/wave number domain and with a 2.5D approach.Three-dimensional numerical models formulated in the time/space domain are less frequently used,mainly due to their high computational cost.Notwithstanding,these models present very attractive characteristics,such as the possibility of considering nonlinear behaviors or the modelling of excess pore pressure and non-homogeneous and non-periodic geometries in the longitudinal direction of the track.In this study,two 3D numerical approaches formulated in the time/space domain are compared and experimentally validated.The first one consists of a finite element approach and the second one of a finite difference approach.The experimental validation in an actual case situated in Carregado(Portugal)shows an acceptable fitting between the numerical results and the actual measurements for both models.However,there are some differences among them.This study therefore includes some recommendations for their use in practical soil dynamics and geotechnical engineering. 展开更多
关键词 railway vibrations time/space domain 3D numerical model finite difference method implicit finite element method
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Study of water renewal and sedimentation of a square harbor encapsulated in a coastal front with seawalls due to wind-induced hydrodynamic circulation 认领
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作者 Yiannis Savvidis Evangelos Keramaris 《国际泥沙研究:英文版》 SCIE 2021年第3期373-383,共11页
In the current study in the middle of a coastal zone,a harbor basin in the form of a square area recessed to the front is considered.A breakwater of variable length and position offers protection from waves.The water ... In the current study in the middle of a coastal zone,a harbor basin in the form of a square area recessed to the front is considered.A breakwater of variable length and position offers protection from waves.The water renewal time and the self-purification capacity of the harbor under the influence of alongshore currents due to wind-induced water circulation of varying intensities were examined.Furthermore,the transport of particulate matter released from the upstream side of the coastal zone and the possible influence(via sedimentation)on the lateral basin was investigated.The current study was based on the use of a two-dimensional depth-averaged hydrodynamic model and a quasi-three-,dimensional transport model while the effect of partial closing of the harbor's entrance was examined.The(1)adjustment and(2)validation of the reliability of the numerical model at a laboratory level were done using a recent research based on the use of a particle image velocimetry(PIV)measurements ensuring very good agreement between numerical and experimental results.The current study showed that the partial closing of the opening between the harbor basin and the extended coastal zone,with a breakwater of length equal to 1/3 of the opening,seems to be the most acceptable technical solution. 展开更多
关键词 Coastal zone Numerical model PIV measurements Renewal time Self-purification capacity Matter transport
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An optimal control model with cost effectiveness analysis of Maize streak virus disease in maize plant 认领
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作者 Haileyesus Tessema Alemneh Assefa Sintayehu Kassa Anteneh Asmare Godana 《传染病建模》 2021年第1期169-182,共14页
In this paper we formulated and analyzed an optimal deterministic eco-epidemiological model for the dynamics of maize streak virus(MSV)and examine the best strategy to fight maize population from maize streak disease(... In this paper we formulated and analyzed an optimal deterministic eco-epidemiological model for the dynamics of maize streak virus(MSV)and examine the best strategy to fight maize population from maize streak disease(MSD).The optimal control model is developed with three control interventions,namely prevention(u1),quarantine(u2)and chemical control(u3).To achieve an optimal control strategy,we used the Pontryagin’s maximum principle obtain the Hamiltonian,the adjoint variables,the characterization of the controls and the optimality system.Numerical simulations are performed using Forward-backward sweep iterative method.The findings show that each integrated strategy is able to mitigate the disease in the specified time.However due to limited resources,it is important to find a cost-effective strategy.Using Incremental Cost-Effectiveness Ratio(ICER)a cost-effectiveness analysis is investigated and determined that the combination of prevention and quarantine is the best cost-effective strategy from the other integrated strategies.Therefore,policymakers and stakeholders should apply the integrated intervention to stop the spread of MSV in the maize population. 展开更多
关键词 MSV Eco-epidemiological model Optimal control theory Numerical simulation Cost-effectiveness analysis
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Investigating different methods used for approximating pillar loads in longwall coal mines 认领
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作者 Deniz Tuncay a Ihsan Berk Tulu a Ted Klemetti 《矿业科学技术学报:英文版》 SCIE EI 2021年第1期23-32,共10页
Accurately estimating load distributions and ground responses around underground openings play a significant role in the safety of the operations in underground mines.Adequately designing pillars and other support mea... Accurately estimating load distributions and ground responses around underground openings play a significant role in the safety of the operations in underground mines.Adequately designing pillars and other support measures relies highly on the accurate assessment of the loads that will be carried by them,as well as the load-bearing capacities of the supports.There are various methods that can be used to approximate mining-induced loads in stratified rock masses to be used in pillar design.The empirical methods are based on equations derived from large databases of various case studies.They are implemented in government approved design tools and are widely used.There are also analytical and numerical techniques used for more detailed analysis of the induced loads.In this study,two different longwall mines with different panel width-to-depth ratios are analyzed using different methods.The empirical method used in the analysis is the square-decay stress function that uses the abutment angle concept,implemented in pillar design software developed by the National Institute for Occupational Safety and Health(NIOSH).The first numerical method used in the analysis is a displacement-discontinuity(DD)variation of the boundary element method,LaModel,which utilizes the laminated overburden model.The second numerical method used in the analysis is Fast Lagrangian Analysis of Continua(FLAC)with the numerical modeling approach recently developed at West Virginia University which is based on the approach developed by NIOSH.The model includes the 2D slice of a cross-section along the width of the panel with the chain pillar system that also includes the different stratigraphic layers of the overburden.All three methods gave similar results for the shallow mine,both in terms of load percentages and distribution where the variation was more obvious for the deep cover mine.The FLAC3D model was observed to better capture the stress changes observed during the field measurements for both the shallow and deep cover cases.This study all 展开更多
关键词 Abutment loads Numerical modeling LaModel FLAC3D Longwall coal mines
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Numerical analysis for the prediction of bump prone conditions:A southern Appalachian pillar coal bump case study 认领
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作者 Christopher Newman David Newman 《矿业科学技术学报:英文版》 SCIE EI 2021年第1期75-81,共7页
Two miners were fatally injured when a pillar bump occurred during retreat mining in a southern West Virginia coal mine.The mine was operating in the Eagle seam with overmining in the No.2 Gas and Powellton seams.A co... Two miners were fatally injured when a pillar bump occurred during retreat mining in a southern West Virginia coal mine.The mine was operating in the Eagle seam with overmining in the No.2 Gas and Powellton seams.A coal bump is defined as a sudden and violent failure of coal caused by the release of stored strain energy in the pillar.While significant strides have been made by academia,industry,and regulatory agencies to better understand bump conditions and mitigation techniques,coal bumps represent a long standing,highly site-specific engineering problem in which the exact failure mechanism is not clearly understood.In this case history,a cut-by-cut analysis of retreat mining operations was conducted on the 4 East Main leading up to the pillar bump event.Numerical input parameters were derived from site-specific geologic information and mine geometry for the analysis of pillar stress conditions and energy release using LaModel.An overview of stress conditions in the panel was presented including a precursor event that occurred two crosscuts inby the bump site.The methodology presented in the paper for the evaluation of the fatal bump event can be used for the identification of bump prone conditions prior to development and retreat of a mining area. 展开更多
关键词 BUMP BURST Coal Energy release rate LaModel Numerical modeling
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Amplification of flood discharge caused by the cascading failure of landslide dams 认领
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作者 Shoki Takayama Masamitsu Fujimoto Yoshifumi Satofuka 《国际泥沙研究:英文版》 SCIE 2021年第3期430-438,共9页
The cascading failure of multiple landslide dams can trigger a larger peak flood discharge than that caused by a single dam failure.Therefore,for an accurate numerical simulation,it is essential to elucidate the prima... The cascading failure of multiple landslide dams can trigger a larger peak flood discharge than that caused by a single dam failure.Therefore,for an accurate numerical simulation,it is essential to elucidate the primary factors affecting the peak discharge of the flood caused by a cascading failure,which is the purpose of the current study.First,flume experiments were done on the cascading failure of two landslide dams under different upstream dam heights,downstream dam heights,and initial downstream reservoir water volumes.Then,the experimental results were reproduced using a numerical simulation model representing landslide dam erosion resulting from overtopping flow.Finally,the factors influencing the peak flood discharge caused by the cascading failure were analyzed using the numerical simulation model.Experimental results indicated that the inflow discharge into the downstream dam at the time when the downstream dam height began to rapidly erode was the main factor responsible for a cascading failure generating a larger peak flood discharge than that generated by a single dam failure.Furthermore,the results of a sensitivity analysis suggested that the upstream and downstream dam heights,initial water volume in the reservoir of the downstream dam,upstream and downstream dam crest lengths,and distance between two dams were among the most important factors in predicting the flood discharge caused by the cascading failure of multiple landslide dams. 展开更多
关键词 Landslide dam Cascading failure Flume experiments Numerical simulation
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Application and prospective of 3D printing in rock mechanics: A review 认领
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作者 Yong-tao Gao Tian-hua Wu Yu Zhou 《矿物冶金与材料学报:英文版》 SCIE EI CAS 2021年第1期1-17,共17页
This review aims to discuss the application and development of three-dimensional printing(3DP) technology in the field of rock mechanics and the mechanical behaviors of 3D-printed specimens on the basis of various ava... This review aims to discuss the application and development of three-dimensional printing(3DP) technology in the field of rock mechanics and the mechanical behaviors of 3D-printed specimens on the basis of various available printing materials.This review begins with a brief description of the concepts and principles associated with 3DP, and then systematically elaborates the five major applications of 3DP technology in the field of rock mechanics, namely, the preparation of rock(including pre-flawed rock) specimens, preparation of joints, preparation of geophysical models, reconstruction of complex rock structures, and performance of bridging experimental testing and numerical simulation.Meanwhile, the mechanical performance of 3D-printed specimens created using six different printing materials, such as polymers, resin,gypsum, sand, ceramics, and rock-like geological materials, is reviewed in detail.Subsequently, some improvements that can make these 3D-printed specimens close to natural rocks and some limitations of 3DP technology in the application of rock mechanics are discussed.Some prospects that are required to be investigated in the future are also proposed.Finally, a brief summary is presented.This review suggests that 3DP technology, especially when integrated with other advanced technologies, such as computed tomography scanning and 3D scanning, has great potential in rock mechanics field. 展开更多
关键词 three-dimensional printing(3DP) rock mechanics 3DP material rock analogue 3DP geotechnical model numerical simulation
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Numerical modeling of local scour at a submerged weir with a downstream slope using a coupled moving-mesh and maskedelement approach 认领
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作者 Xiaohui Yan Colin David Rennie Abdolmajid Mohammadian 《国际泥沙研究:英文版》 SCIE 2021年第2期279-290,共12页
This paper presents a model for local scour at submerged weirs with downstream slopes that uses a coupled moving-mesh and masked-element approach.In the developed model,the fluid-sediment interface is tracked using a ... This paper presents a model for local scour at submerged weirs with downstream slopes that uses a coupled moving-mesh and masked-element approach.In the developed model,the fluid-sediment interface is tracked using a moving-mesh technique,and the effects of the structure on the hydrodynamics and bed morphology are resolved using a masked-element technique.Compared to traditional sediment scour models,based on the moving-mesh technique,the present model has the advantage of allowing for a simpler setup of the computational grids and a larger-amplitude deformation.Laboratory experiments on local scour at a submerged weir with a downstream slope were conducted,which provided bed profiles at different time instants.The results obtained by the present model are compared to the experimental data.The comparisons demonstrate the performance of the model in satisfactorily predicting local scour at a submerged weir with a downstream slope.The model was further modified and employed to carry out additional computations to investigate the influence of various parameters and sub-models. 展开更多
关键词 Numerical modeling Bed morphology Submerged weir Downstream slope Moving-mesh and masked-element OpenFOAM
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FE modeling of concrete beams and columns reinforced with FRP composites 认领
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作者 Farid Abed Chahmi Oucif +2 位作者 Yousef Awera Haya H.Mhanna Hakem Alkhraisha 《Defence Technology(防务技术)》 SCIE EI CAS 2021年第1期1-14,共14页
Compression and flexure members such as columns and beams are critical in a structure as its failure could lead to the collapse of the structure.In the present work,numerical analysis of square and circle short column... Compression and flexure members such as columns and beams are critical in a structure as its failure could lead to the collapse of the structure.In the present work,numerical analysis of square and circle short columns,and reinforced concrete(RC)beams reinforced with fiber reinforced polymer composites are carried out.This work is divided into two parts.In the first part,numerical study of axial behavior of square and circular concrete columns reinforced with Glass Fiber Reinforced Polymer(GFRP)and Basalt Fiber Reinforced Polymer(BFRP)bars and spiral,and Carbon Fiber Reinforced Polymer(CFRP)wraps is conducted.The results of the first part showed that the axial capacity of the circular RC columns reinforced with GFRP increases with the increase of the longitudinal reinforcement ratio.In addition,the results of the numerical analysis showed good correlation with the experimental ones.An interaction diagram for BFRP RC columns is also developed with considering various eccentricities.The results of numerical modeling of RC columns strengthened with CFRP wraps revealed that the number and the spacing between the CFRP wraps provide different levels of ductility enhancement to the column.For the cases considered in this study,column with two middle closely spaced CFRP wraps demonstrated the best performance.In the second part of this research,flexural behavior of RC beams reinforced with BFRP,GFRP and CFRP bars is investigated along with validation of the numerical model with the experimental tests.The results resembled the experimental observations that indicate significant effect of the FRP bar diameter and type ont he flexural capacity of the RC beams.It was also shown that Increasing the number of bars while keeping the same reinforcement ratio enhanced the stiffness of the RC beam. 展开更多
关键词 Numerical analysis BRFP GFRP CFRP COLUMNS BEAMS Experimental tests
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Numerical simulation study on penetration performance of depleted Uranium(DU)alloy fragments 认领
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作者 Fu-lin Zhu Yang Chen Gui-li Zhu 《Defence Technology(防务技术)》 SCIE EI CAS 2021年第1期50-55,共6页
Due to its high strength,high density,high hardness and good penetration capabilities,Depleted uranium alloys have already shined in armor-piercing projectiles.There should also be a lot of room for improvement in the... Due to its high strength,high density,high hardness and good penetration capabilities,Depleted uranium alloys have already shined in armor-piercing projectiles.There should also be a lot of room for improvement in the application of fragment killing elements.Therefore,regarding the performance of the depleted uranium alloy to penetrate the target plate,further investigation is needed to analyze its advantages and disadvantages compared to tungsten alloy.To study the difference in penetration performance between depleted uranium alloy and tungsten alloy fragments,firstly,a theoretical analysis of the adiabatic shear sensitivity of DU and tungsten alloys was given from the perspective of material constitutive model.Then,taking the cylindrical fragment penetration target as the research object,the penetration process and velocity characteristics of the steel target plates penetrated by DU alloy fragment and tungsten alloy fragment were compared and analyzed,by using finite element software ANSYS/LS-DYNA and Lagrange algorithm.Lastly,the influence of different postures when impacting target and different fragment shapes on the penetration results is carried out in the research.The results show that in the penetration process of the DU and tungsten alloy fragments,the self-sharpening properties of the DU alloy can make the fragment head sharper and the penetrating ability enhance.Under the same conditions,the penetration capability of cylindrical fragment impacting target in vertical posture is better than that in horizontal posture,and the penetration capability of the spherical fragment is slightly better than that of cylindrical fragment. 展开更多
关键词 Depleted uranium alloy Constitutive model Adiabatic shear Penetration performance Numerical simulation
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Mitigation of the blast load effects on a building structure using newly composite structural configurations 认领
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作者 Ahmed K.Taha M.S.Zahran Zhengguo Gao 《Defence Technology(防务技术)》 SCIE EI CAS 2021年第1期75-84,共10页
In this study,a nonlinear three-dimensional hydrocode numerical simulation was carried out using AUTODYN-3D to investigate the effect of blasting of a high explosive material(TNT)against several configurations of the ... In this study,a nonlinear three-dimensional hydrocode numerical simulation was carried out using AUTODYN-3D to investigate the effect of blasting of a high explosive material(TNT)against several configurations of the composite structure.Several numerical models were carried out to study the effect of varying the thickness of the walls and the effect of adding an air layer or aluminum foam layer inside two layers of concrete in mitigating the effect of blast waves on the structure walls.The results showed that increasing the thickness of walls has a good effect on mitigating the effect of blast waves.When a layer of air was added,the effect of blast waves was exaggerated,while when a layer of aluminum foam was added the blast wave effects were mitigated with a reasonable percentage. 展开更多
关键词 Concrete structures Blast waves Numerical simulation TNT
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Numerical Simulation to Evaluate the Effects of Upward Lightning Discharges on Thunderstorm Electrical Parameters 认领
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作者 Tianxue ZHENG Yongbo TAN Yiru WANG 《大气科学进展:英文版》 SCIE CAS 2021年第3期446-459,共14页
A theoretical discussion of the discharge effects of upward lightning simulated with a fine-resolution 2D thunderstorm model is performed in this paper,and the results reveal that the estimates of the total induced ch... A theoretical discussion of the discharge effects of upward lightning simulated with a fine-resolution 2D thunderstorm model is performed in this paper,and the results reveal that the estimates of the total induced charge on the upward lightning discharge channels range from 0.67 to 118.8 C,and the average value is 19.0 C,while the ratio of the induced charge on the leader channels to the total opposite-polarity charge in the discharge region ranges from 5.9%to 47.3%,with an average value of 14.7%.Moreover,the average value of the space electrostatic energy consumed by upward lightning is 1.06×10^9 J.The above values are lower than those related to intracloud lightning discharges.The density of the deposited opposite-polarity charge is comparable in magnitude to that of the preexisting charge in the discharge area,and the deposition of these opposite-polarity charges rapidly destroys the original space potential well in the discharge area and greatly reduces the space electric field strength.In addition,these opposite-polarity charges are redistributed with the development of thunderstorms.The space charge redistribution caused by lightning discharges partly accounts for the complexity of the charge structures in a thunderstorm,and the complexity gradually decreases with the charge neutralization process. 展开更多
关键词 numerical simulation upward lightning induced charge variation of charge distribution electrostatic energy
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Sensitivity analysis of influencing parameters on slit-type barrier performance against debris flow using 3D-based numerical approach 认领
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作者 Minseop Kim Seungrae Lee +2 位作者 Tae-Hyuk Kwon Shin-Kyu Choi Jun-Seo Jeon 《国际泥沙研究:英文版》 SCIE 2021年第1期50-62,共13页
Extreme rainfall-induced debris flow can be catastrophic to an urban area,and installation of slit-type barriers can prevent such damage while minimizing negative impact on environments.However,the performance of slit... Extreme rainfall-induced debris flow can be catastrophic to an urban area,and installation of slit-type barriers can prevent such damage while minimizing negative impact on environments.However,the performance of slit-type barriers against debris flows remains poorly identified partly due to the innate complexity in interactions between debris flow and solid structure.This paper investigated the flow behaviors of debris affected by slit-type barriers using the computational fluid dynamics(CFD)method,in which the numerical model based on the volume of fluid method was verified using the physical modeling results.The sensitivity analysis was performed by building metamodels to determine the primary parameters influencing the barrier performance against debris flows among various variables,in which the effect of input properties and design parameters,particularly the soil concentration in fluidized debris,initial velocity and volume of debris,the barrier height,and the opening ratio,was evaluated from the perspectives of the flow energy reduction and debris trapping.The initial velocity and volume of debris were found to play a significant role in determining the debris flow characteristics.A decrease in the opening ratio in the channel primarily facilitated the energy reduction and trapping due to the reduced opening size.However,the barrier height exhibited a limited effect when the height was sufficiently high to block the debris flow volume.In addition,it was observed that the double barrier system effectively increased the energy reduction while keeping the benefit of open-type barrier.The developed simulation method and obtained results provide an effective tool and an insight that can contribute to an optimum design of the debris-flow barrier. 展开更多
关键词 Debris flow Slit-type barrier Numerical simulations Sensitivity analysis Mitigation effect
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Multiply accumulate operations in memristor crossbar arrays for analog computing 认领
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作者 Jia Chen Jiancong Li +1 位作者 Yi Li Xiangshui Miao 《半导体学报:英文版》 EI CAS 2021年第1期90-111,共22页
Memristors are now becoming a prominent candidate to serve as the building blocks of non-von Neumann inmemory computing architectures.By mapping analog numerical matrices into memristor crossbar arrays,efficient multi... Memristors are now becoming a prominent candidate to serve as the building blocks of non-von Neumann inmemory computing architectures.By mapping analog numerical matrices into memristor crossbar arrays,efficient multiply accumulate operations can be performed in a massively parallel fashion using the physics mechanisms of Ohm’s law and Kirchhoff’s law.In this brief review,we present the recent progress in two niche applications:neural network accelerators and numerical computing units,mainly focusing on the advances in hardware demonstrations.The former one is regarded as soft computing since it can tolerant some degree of the device and array imperfections.The acceleration of multiple layer perceptrons,convolutional neural networks,generative adversarial networks,and long short-term memory neural networks are described.The latter one is hard computing because the solving of numerical problems requires high-precision devices.Several breakthroughs in memristive equation solvers with improved computation accuracies are highlighted.Besides,other nonvolatile devices with the capability of analog computing are also briefly introduced.Finally,we conclude the review with discussions on the challenges and opportunities for future research toward realizing memristive analog computing machines. 展开更多
关键词 analog computing MEMRISTOR multiply accumulate(MAC)operation neural network numerical computing
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文章速递Effects of operating parameters on the flow field in slab continuous casting molds with narrow widths 认领
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作者 Tao Zhang Jian Yang +3 位作者 Gang-jun Xu Hong-jun Liu Jun-jun Zhou Wei Qin 《矿物冶金与材料学报:英文版》 SCIE EI CAS CSCD 2021年第2期238-248,共11页
Computational simulations and high-temperature measurements of velocities near the surface of a mold were carried out by using the rod deflection method to study the effects of various operating parameters on the flow... Computational simulations and high-temperature measurements of velocities near the surface of a mold were carried out by using the rod deflection method to study the effects of various operating parameters on the flow field in slab continuous casting(CC)molds with narrow widths for the production of automobile exposed panels.Reasonable agreement between the calculated results and measured subsurface velocities of liquid steel was obtained under different operating parameters of the CC process.The simulation results reveal that the flow field in the horizontal plane located 50 mm from the meniscus can be used as the characteristic flow field to optimize the flow field of molten steel in the mold.Increases in casting speed can increase the subsurface velocity of molten steel and shift the position of the vortex core downward in the downward circulation zone.The flow field of liquid steel in a 1040 mm-wide slab CC mold can be improved by an Ar gas flow rate of 7 L·min^−1 and casting speed of 1.7 m·min^−1.Under the present experimental conditions,the double-roll flow pattern is generally stable at a submerged entry nozzle immersion depth of 170 mm. 展开更多
关键词 flow field rod deflection method continuous casting narrow width numerical simulation operating parameters
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