We develop and implement a Stochastic Discrete Event Simulation(SDES)algorithm to model the housing re-covery trajectory after an extreme event.The algorithm models discrete events and their underlying uncertainties i...We develop and implement a Stochastic Discrete Event Simulation(SDES)algorithm to model the housing re-covery trajectory after an extreme event.The algorithm models discrete events and their underlying uncertainties in each construction phase.Specifically,the algorithm is developed for the Government Assisted Owner Driven(GAOD)reconstruction system to simulate long-term recovery trajectory.SDES,as a flexible modeling approach,can simulate any housing recovery scenario that follows phased reconstruction.The 2015 M 7.8 Gorkha earthquake sequence in Nepal is considered the extreme event,with 796,245 buildings requiring reconstruction.We present some recovery trajectories from severely hit,crisis hit,and earthquake hit parishes,comparing them with the actual reconstruction progress.We also assess quality and improvement of reconstructed buildings using seismic fragility functions,compared to pre-earthquake constructions.Housing recovery uncertainties are dissected in relation to reconstruction pace.We conclude that the vast majority of the reconstructed buildings followed the Build Back Better(BBB)approach and missed the opportunity to pursue the Build Back Resilient(BBR)approach due to multifaceted challenges ranging from unclear policies to economic constraints.We critically assess the GAOD vs Owner Driven(OD)recovery framework and conclude that insurance-supported and technically assisted OD approach could be the most suitable model for post extreme event housing recovery.展开更多
Aiming at the actual demand for the maintenance support of new general equipments, this paper analyzes the structure and circulation of maintenance support system, builds the simulation model of running process by ent...Aiming at the actual demand for the maintenance support of new general equipments, this paper analyzes the structure and circulation of maintenance support system, builds the simulation model of running process by entity flow chart method, and constructs the basic frame of the simulation model. The generating method of random variables and the advancing process of the simulation clock are described, and the accurate prediction of maintenance equipment is realized. Moreover, the material readiness rate is analyzed in statistics objective to evaluate the simulation result. The research is of significance for improving the efficiency of equipment maintenance and the promotion of material readiness rate.展开更多
This study aims to formulate a steady-state mathematical model for a three-dimensional permeable enclosure(cavity)to determine the oil extraction rate using three distinct nanoparticles,SiO_(2),Al_(2)O_(3),and Fe_(2)O...This study aims to formulate a steady-state mathematical model for a three-dimensional permeable enclosure(cavity)to determine the oil extraction rate using three distinct nanoparticles,SiO_(2),Al_(2)O_(3),and Fe_(2)O_(3),in unconventional oil reservoirs.The simulation is conducted for different parameters of volume fractions,porosities,and mass flow rates to determine the optimal oil recovery.The impact of nanoparticles on relative permeability(kr)and water is also investigated.The simulation process utilizes the finite volume ANSYS Fluent.The study results showed that when the mass flow rate at the inlet is low,oil recovery goes up.In addition,they indicated that silicon nanoparticles are better at getting oil out of the ground(i.e.,oil reservoir)than Al_(2)O_(3)and Fe_(2)O_(3).Most oil can be extracted from SiO_(2),Al_(2)O_(3),and Fe_(2)O_(3)at a rate of 97.8%,96.5%,and 88%,respectively.展开更多
The recovery rate of coalbed methane (CBM) can reflect the mining situation and the residual gas in coal reservoir. It plays an important role in the calculation of the recoverable resources. This paper mainly uses is...The recovery rate of coalbed methane (CBM) can reflect the mining situation and the residual gas in coal reservoir. It plays an important role in the calculation of the recoverable resources. This paper mainly uses isothermal adsorption curve method and hydraulic model method to predict recovery rate of CBM. The isothermal adsorption curve method considering desorption lag problem in the prediction process, which is more in line with the actual situation. In the hydraulic model method, the recovery rate of “V” type well is the largest in the early stage. But with the time going on, the recovery rate of multilateral horizontal well is greater than vertical well, “U” type well and “V” type well finally. The factors affecting CBM recovery rate include geological characteristics, development conditions and economic factors. The geological characteristics of coal reservoir are the main factors affecting CBM recovery rate, and corresponding measures can be adopted to improve the recovery rate.展开更多
The Intalox metal tower packing was used to simulate an industrial relevant extractive distillation column for purifying azeotropic multicomponent mixture.In order to explain the inconsistencies in the modeling of tra...The Intalox metal tower packing was used to simulate an industrial relevant extractive distillation column for purifying azeotropic multicomponent mixture.In order to explain the inconsistencies in the modeling of transfer process in nonideal multicomponent distillation column,a method was developed with equilibrium stage models(EQ)and non-equilibrium model(NEQ)incorporated with Maxwell-Stefan diffusion equations in the framework of AspenONE simulator.Dortmund Modified UNIFAC(UNIFAC-DMD)thermodynamic model was employed to estimate activity coefficients.In addition,to understand the reason for the diffusion against driving force and the different results by EQ and NEQ models,explicit investigations were made on diffusion coefficients, component Murphree efficiency and mass transfer coefficients.The results provide valuable information for basic design and applications associated with extractive distillation.展开更多
This paper introduces the main methods and steps of modeling principle by ordinary differential equations, and is used to explore the differential equation model to solve some practical problems, some features of the ...This paper introduces the main methods and steps of modeling principle by ordinary differential equations, and is used to explore the differential equation model to solve some practical problems, some features of the related problems. With the development of science and technology and production practice, differential equation is more closely connected with other subjects, and a mathematical model for some practical problems of good.展开更多
Depositional growth of ice crystal is one of the major processes for development of precipitation systems and can be represented by depositional growth of cloud ice from cloud water(P_(IDW)) and depositional growth of...Depositional growth of ice crystal is one of the major processes for development of precipitation systems and can be represented by depositional growth of cloud ice from cloud water(P_(IDW)) and depositional growth of snow from cloud ice(P_(SFI)) in cloud-resolving model. Four parameterization schemes are analyzed in the cloud-resolving model simulations of four rainfall cases over the tropics and midlatitudes. The comparison of time and model domain mean data shows that Shen's scheme produces the closest rainfall simulation to the observation. Compared to Zeng's scheme,Shen's scheme improves the mean rain-rate simulation significantly through the dramatic decrease in depositional growth of cloud ice from cloud water. Compared to other schemes, Shen's scheme produces the better rainfall simulation via the reduction in the mean rain rate associated with the enhanced gain of cloud water and ice.展开更多
A major challenge in enhancing the resilience of communities stems from current approaches used to identify needs and strategies that build the capacity of jurisdictions to mitigate loss and improve recovery. A new ge...A major challenge in enhancing the resilience of communities stems from current approaches used to identify needs and strategies that build the capacity of jurisdictions to mitigate loss and improve recovery. A new generation of resilience-based planning processes has emerged in the last several years that integrate goals of community well-being and identity into recovery-based performance measurement frameworks. Specific tools and refined guidance are needed to facilitate evidence-based development of recovery estimates. This article presents the participatory modeling process, a planning system designed to develop recovery-based resilience measurement frameworks for community resilience planning initiatives. Stakeholder engagement is infused throughout the participatory modeling process by integrating disaster recovery simulation modeling into community resilience planning. Within the process, participants get a unique opportunity to work together to deliberate on community concerns through facilitated participatory modeling. The participatory modeling platform combines the DESaster recovery simulation model and visual analytics interfaces.DESaster is an open source Python Library for creating discrete event simulations of disaster recovery. The simulation model was developed using a human-centered design approach whose goal is to be open, modular, and extensible. The process presented in this article is the first participatory modeling approach for analyzing recovery to aid creation of community resilience measurement frameworks.展开更多
Restoring lifeline services to an urban neighborhood impacted by a large disaster is critical to the recovery of the city as a whole.Since cities are comprised of many dependent lifeline systems,the pattern of the res...Restoring lifeline services to an urban neighborhood impacted by a large disaster is critical to the recovery of the city as a whole.Since cities are comprised of many dependent lifeline systems,the pattern of the restoration of each lifeline system can have an impact on one or more others.Due to the often uncertain and complex interactions between dense lifeline systems and their individual operations at the urban scale,it is typically unclear how different patterns of restoration will impact the overall recovery of lifeline system functioning.A difficulty in addressing this problem is the siloed nature of the knowledge and operations of different types of lifelines.Here,a city-wide,multi-lifeline restoration model and simulation are provided to address this issue.The approach uses the Graph Model for Operational Resilience,a data-driven discrete event simulator that can model the spatial and functional cascade of hazard effects and the pattern of restoration over time.A novel case study model of the District of North Vancouver is constructed and simulated for a reference magnitude 7.3 earthquake.The model comprises municipal water and wastewater,power distribution,and transport systems.The model includes 1725 entities from within these sectors,connected through 6456 dependency relationships.Simulation of the model shows that water distribution and wastewater treatment systems recover more quickly and with less uncertainty than electric power and road networks.Understanding this uncertainty will provide the opportunity to improve data collection,modeling,and collaboration with stakeholders in the future.展开更多
Recovery of waste heat from boiler flue gas is an effective way to improve energy utilization efficiency.Taking a heating station heating project as an example,the existing heating system of this heating station was a...Recovery of waste heat from boiler flue gas is an effective way to improve energy utilization efficiency.Taking a heating station heating project as an example,the existing heating system of this heating station was analyzed for its underutilized flue gas waste heat and low energy utilization rate.Rankine cycle is an effective waste heat recovery method,and a steam boiler organic Rankine cycle(ORC)cogeneration waste heat utilization method is proposed.The system model simulation is constructed and verified.First,a thermodynamic model was constructed in MATLAB and five suitable work gases were selected to analyze the effects of evaporation temperature and condensation temperature on the network and thermal efficiency of the waste heat cycle power system.Secondly,the ORC model is invoked in TRNSYS to construct the improved cogeneration system,and the rationality of the remaining heat utilization methods is determined by calculating and analyzing the thermal performance,economy,and environmental protection of the improved system.The simulation results show that the system can generate about 552,000 kWh of electricity per year,and improving the energy utilization rate from 0.72 to 0.78.展开更多
Ground-coupled heat pumps(GCHP)are commonly used in residential heating system.To mitigate the boreholes temperature dropping with operating time,a new exhaust-air recharging system is developed.The new recharging sys...Ground-coupled heat pumps(GCHP)are commonly used in residential heating system.To mitigate the boreholes temperature dropping with operating time,a new exhaust-air recharging system is developed.The new recharging system can be used in three operational modes.In this paper,a ground-coupled heat recovery ventilation(HRV)model is discussed.A thermal model is set up to find the optimal brine flow rate and heat transfer allocation ratio between exhaust and supply coils for maximum heat recovery efficiency.Contrary to the conventional liquid-loop HRV systems,the brine temperature entering the exhaust coil never goes blow zero(0℃),and hence defrosting is needless in the ground-coupled HRV system.This can make the ground-coupled HRV system over 20% more efficient than a conventional HRV system at low outdoor temperatures.展开更多
This paper considers an improved model of pricing defaultable bonds under the assumption that the interest rate satisfies the Vasicek model driven by fractional Brownian motion(fBm for short)based on the counterparty ...This paper considers an improved model of pricing defaultable bonds under the assumption that the interest rate satisfies the Vasicek model driven by fractional Brownian motion(fBm for short)based on the counterparty risk framework of Jarrow and Yu(2001). The authors use the theory of stochastic analysis of f Bm to derive pricing formulas for the defaultable bonds and study how the counterparty risk, recovery rate, and the Hurst parameter affect the values of the defaultable bonds.Numerical experiment results are presented to demonstrate the findings.展开更多
A generalized rate model for free radical copolymerization was proposed. It can be applied not only to the system with the participation of charge-transfer complex (CTC), but also to the system without the participati...A generalized rate model for free radical copolymerization was proposed. It can be applied not only to the system with the participation of charge-transfer complex (CTC), but also to the system without the participation of CTC. The effects of equilibrium constant, total monomer concentration, homo-propagation parameters and reactivity ratios on free monomer, CTC, overall rates, and the contribution of CTC were considered in the simulation. North equation of copolymerization rate as a special case can be derived from the generalized model.展开更多
Optimum utilization of the loading capability of engineering materials is an important and active contribution to protect nature's limited resources,and it is the key for economic design methods.In order to make u...Optimum utilization of the loading capability of engineering materials is an important and active contribution to protect nature's limited resources,and it is the key for economic design methods.In order to make use of the materials' resources,those must be known very well;but conventional test methods will offer only limited informational value.The range of questions raised is as wide as the application of engineering materials,and partially they are very specific.The development of huge computer powers enables numeric modelling to simulate structural behaviour in rather complex loading environments-so the real material behaviour is known under the given loading conditions.Here the art of material testing design starts.To study the material behaviour under very distinct and specific loading conditions makes it necessary to simulate different temperature ranges,loading speeds, environments etc.and mostly there doesn't exist any commonly agreed test standard.In this contribution two popular,non-standard test procedures and test systems will be discussed on the base of their application background,special design features as well as test results and typically gained information:The demand for highspeed tests up to 1000 s^(-1) of strain rate is very specific and originates primarily in the automotive industry and the answers enable CAE analysis of crashworthiness of vehicle structures under crash conditions.The information on the material behaviour under multiaxial loading conditions is a more general one.Multiaxial stress states can be reduced to an equivalent stress,which allows the evaluation of the material's constraint and criticality of stress state.Both discussed examples shall show that the open dialogue between the user and the producer of testing machines allows custom-tailored test solutions.展开更多
Modeling, simulation, and prediction of global energy indices remain veritable tools for econometric, engineering, analysis, and prediction of energy indices. Thus, this paper differentially modeled, simulated, and no...Modeling, simulation, and prediction of global energy indices remain veritable tools for econometric, engineering, analysis, and prediction of energy indices. Thus, this paper differentially modeled, simulated, and non-differentially predicated the global energy indices. The state-of-the-art of the research includes normalization of energy indices, generation of differential rate terms, and regression of rate terms against energy indices to generate coefficients and unexplained terms. On imposition of initial conditions, the solution to the system of linear differential equations was realized in a Matlab environment. There was a strong agreement between the simulated and the field data. The exact solutions are ideal for interpolative prediction of historic data. Furthermore, the simulated data were upgraded for extrapolative prediction of energy indices by introducing an innovative model, which is the synergy of deflated and inflated prediction factors. The innovative model yielded a trendy prediction data for energy consumption, gross domestic product, carbon dioxide emission and human development index. However, the oil price was untrendy, which could be attributed to odd circumstances. Moreover, the sensitivity of the differential rate terms was instrumental in discovering the overwhelming effect of independent indices on the dependent index. Clearly, this paper has accomplished interpolative and extrapolative prediction of energy indices and equally recommends for further investigation of the untrendy nature of oil price.展开更多
Accurate prediction of the aerodynamic response of a compressor under inlet distortion is crucial for next-generation civil aircraft,such as Boundary Layer Ingestion(BLI)silent aircraft.Therefore,research on the Body ...Accurate prediction of the aerodynamic response of a compressor under inlet distortion is crucial for next-generation civil aircraft,such as Boundary Layer Ingestion(BLI)silent aircraft.Therefore,research on the Body Force(BF)model plays a significant role in achieving this objective.However,distorted inlet airflow can lead to varying operating conditions across different spatial locations of the compressor,which may cause some regions to operate outside the stability boundary.Consequently,the accuracy of BF model simulations might be compromised.To address this issue,this paper proposes a numerical simulation strategy for acquiring the steady axisymmetric three-dimensional flow field of a compressor operating at low mass flow rates,which is known as the Underlying Axisymmetric Pressure Rise Characteristic(UAPRC).The proposed simulation accounts for two different rotor speeds of a transonic compressor and identifies initial positions in the flow field where deterioration occurs based on prior experimental investigations.Moreover,simulation results are incorporated into the BF model to replicate hub instability observed in experiments.Obtained results demonstrate that this strategy provides valid predictions of the UAPRC of the compressor,thereby addressing the limitations associated with the BF model.展开更多
A non-equilibrium chromatographic rate model was employed to simulate the affinity chromatography of urokinase. The chromatography process was developed to a yield of high purity product of urokinase from crude materi...A non-equilibrium chromatographic rate model was employed to simulate the affinity chromatography of urokinase. The chromatography process was developed to a yield of high purity product of urokinase from crude materials. The affinity gel used in the process was prepared by an epichlorohydrin-activation method using epichlorohydrin activated Sepharose 4B as a matrix and p-aminobenzamidine as a ligand. The chromatographic process were numerically simulated and analyzed with the aid of VERSE-LC computer simulator. Considering the basic principles, rate model with the back mixing in column inlet was utilized in simulating and studying the effect of the column inlet pattern on other parameters. Comparison of the simulation results with the experimental data showed that the rate model can be used to describe the affinity chromatography of urokinase in a fixed bed column with satisfactory accuracy.展开更多
Oilfields worldwide are increasingly grappling with challenges such as early water breakthrough and high water production,yet direct,targeted solutions remain elusive.In recent years,chemical flooding techniques desig...Oilfields worldwide are increasingly grappling with challenges such as early water breakthrough and high water production,yet direct,targeted solutions remain elusive.In recent years,chemical flooding techniques designed for tertiary oil recovery have garnered significant attention,with microgel flooding emerging as a particularly prominent area of research.Despite its promise,the complex mechanisms underlying microgel flooding have been rarely investigated numerically.This study aims to address these gaps by characterizing the distribution of microgel concentration and viscosity within different pore structures.To enhance the accuracy of these characterizations,the viscosity of microgels is adjusted to account for the shear effects induced by flow rate and the swelling effects driven by salinity variations.The absolute permeability of the rock and the relative permeability of both oil and microgel are also analyzed to elucidate the mechanisms of microgel flooding.Additionally,a connectivity model is employed to achieve a quantitative representation of fluid flow capacity.The proposed model is validated through conceptual examples and applied to real oilfield blocks,demonstrating its accuracy and practical applicability.展开更多
在“双碳”目标背景下,为推动CO_(2)驱气提高采收率技术发展,明确注气提高采收率关键参数,模拟研究基于长岩心驱替实验,通过拟合实验数据建立数值模拟模型,系统研究了注气时机、注气速度、束缚水饱和度以及开发方式等关键参数对采收率...在“双碳”目标背景下,为推动CO_(2)驱气提高采收率技术发展,明确注气提高采收率关键参数,模拟研究基于长岩心驱替实验,通过拟合实验数据建立数值模拟模型,系统研究了注气时机、注气速度、束缚水饱和度以及开发方式等关键参数对采收率的影响。研究结果表明:①裂缝性气藏中裂缝是主要渗流通道,注入气体驱替天然气过程分为未突破和突破两阶段,未突破阶段持续时间越长,采收率越高;②提高转注压力可以增强气体驱替能力、延迟CO_(2)突破,对提高天然气采收率和CO_(2)埋存率有积极影响;③注气速度越快,气体波及范围越大,CH_(4)采收率越高,但CO_(2)埋存率降低;④束缚水饱和度对采收率和埋存率具有一定影响,束缚水饱和度增加,CH_(4)采收率提高,CO_(2)埋存率降低;⑤提前注气增压可缩短开采时间并提升CH_(4)采收率,但会降低CO_(2)埋存率。结论认为,本次模拟研究成果为优化CO_(2)-EGR(enhanced gas recovery)技术参数、降低成本、提高经济效益提供了理论依据,对推动天然气资源高效开发和实现碳减排具有重要意义。展开更多
Basic structure and algorithm of leaf mechanism photosynthesis model were described in first part of this study based on former researcher results. Then, considering some environmental factors influencing on leaf ph...Basic structure and algorithm of leaf mechanism photosynthesis model were described in first part of this study based on former researcher results. Then, considering some environmental factors influencing on leaf photosynthesis, three numerical sensitivity experiments were carried out. We simulated the sing le leaf net CO2 assimilation, which acts as a function of different light, carbo n dioxide and temperature conditions. The relationships between leaf net photosy nthetic rate of C3 and C4 plant with CO2 concentration intercellular, leaf tempe rature, and photosynthetic active radiation (PAR) were presented, respectively. The results show the numerical experiment may indicate the main characteristic o f plant photosynthesis in C3 and C4 plant, and further can be used to integrate with the regional climate model and act as land surface process scheme, and bett er understand the interaction between vegetation and atmosphere.展开更多
文摘We develop and implement a Stochastic Discrete Event Simulation(SDES)algorithm to model the housing re-covery trajectory after an extreme event.The algorithm models discrete events and their underlying uncertainties in each construction phase.Specifically,the algorithm is developed for the Government Assisted Owner Driven(GAOD)reconstruction system to simulate long-term recovery trajectory.SDES,as a flexible modeling approach,can simulate any housing recovery scenario that follows phased reconstruction.The 2015 M 7.8 Gorkha earthquake sequence in Nepal is considered the extreme event,with 796,245 buildings requiring reconstruction.We present some recovery trajectories from severely hit,crisis hit,and earthquake hit parishes,comparing them with the actual reconstruction progress.We also assess quality and improvement of reconstructed buildings using seismic fragility functions,compared to pre-earthquake constructions.Housing recovery uncertainties are dissected in relation to reconstruction pace.We conclude that the vast majority of the reconstructed buildings followed the Build Back Better(BBB)approach and missed the opportunity to pursue the Build Back Resilient(BBR)approach due to multifaceted challenges ranging from unclear policies to economic constraints.We critically assess the GAOD vs Owner Driven(OD)recovery framework and conclude that insurance-supported and technically assisted OD approach could be the most suitable model for post extreme event housing recovery.
基金the National Natural Science Foundation of China(No.71401173)
文摘Aiming at the actual demand for the maintenance support of new general equipments, this paper analyzes the structure and circulation of maintenance support system, builds the simulation model of running process by entity flow chart method, and constructs the basic frame of the simulation model. The generating method of random variables and the advancing process of the simulation clock are described, and the accurate prediction of maintenance equipment is realized. Moreover, the material readiness rate is analyzed in statistics objective to evaluate the simulation result. The research is of significance for improving the efficiency of equipment maintenance and the promotion of material readiness rate.
基金The APC of this article is covered by Research Grant YUTP 015LCO-526。
文摘This study aims to formulate a steady-state mathematical model for a three-dimensional permeable enclosure(cavity)to determine the oil extraction rate using three distinct nanoparticles,SiO_(2),Al_(2)O_(3),and Fe_(2)O_(3),in unconventional oil reservoirs.The simulation is conducted for different parameters of volume fractions,porosities,and mass flow rates to determine the optimal oil recovery.The impact of nanoparticles on relative permeability(kr)and water is also investigated.The simulation process utilizes the finite volume ANSYS Fluent.The study results showed that when the mass flow rate at the inlet is low,oil recovery goes up.In addition,they indicated that silicon nanoparticles are better at getting oil out of the ground(i.e.,oil reservoir)than Al_(2)O_(3)and Fe_(2)O_(3).Most oil can be extracted from SiO_(2),Al_(2)O_(3),and Fe_(2)O_(3)at a rate of 97.8%,96.5%,and 88%,respectively.
文摘The recovery rate of coalbed methane (CBM) can reflect the mining situation and the residual gas in coal reservoir. It plays an important role in the calculation of the recoverable resources. This paper mainly uses isothermal adsorption curve method and hydraulic model method to predict recovery rate of CBM. The isothermal adsorption curve method considering desorption lag problem in the prediction process, which is more in line with the actual situation. In the hydraulic model method, the recovery rate of “V” type well is the largest in the early stage. But with the time going on, the recovery rate of multilateral horizontal well is greater than vertical well, “U” type well and “V” type well finally. The factors affecting CBM recovery rate include geological characteristics, development conditions and economic factors. The geological characteristics of coal reservoir are the main factors affecting CBM recovery rate, and corresponding measures can be adopted to improve the recovery rate.
基金Supported by the National Natural Science Foundation of China （20776118）, Science ＆ Technology Bureau of Xi＇an [CXY09019 （1）], Innovation Foundation for Graduated Student of Northwest University （08YJC21）, Shaanxi Research Center of Engineering Technology for Clean Coal Conversion （2008ZDGC-13）.
文摘The Intalox metal tower packing was used to simulate an industrial relevant extractive distillation column for purifying azeotropic multicomponent mixture.In order to explain the inconsistencies in the modeling of transfer process in nonideal multicomponent distillation column,a method was developed with equilibrium stage models(EQ)and non-equilibrium model(NEQ)incorporated with Maxwell-Stefan diffusion equations in the framework of AspenONE simulator.Dortmund Modified UNIFAC(UNIFAC-DMD)thermodynamic model was employed to estimate activity coefficients.In addition,to understand the reason for the diffusion against driving force and the different results by EQ and NEQ models,explicit investigations were made on diffusion coefficients, component Murphree efficiency and mass transfer coefficients.The results provide valuable information for basic design and applications associated with extractive distillation.
文摘This paper introduces the main methods and steps of modeling principle by ordinary differential equations, and is used to explore the differential equation model to solve some practical problems, some features of the related problems. With the development of science and technology and production practice, differential equation is more closely connected with other subjects, and a mathematical model for some practical problems of good.
基金National Natural Science Foundation of China(41475039)National Key Basic Research and Development Project of China(2015CB953601)
文摘Depositional growth of ice crystal is one of the major processes for development of precipitation systems and can be represented by depositional growth of cloud ice from cloud water(P_(IDW)) and depositional growth of snow from cloud ice(P_(SFI)) in cloud-resolving model. Four parameterization schemes are analyzed in the cloud-resolving model simulations of four rainfall cases over the tropics and midlatitudes. The comparison of time and model domain mean data shows that Shen's scheme produces the closest rainfall simulation to the observation. Compared to Zeng's scheme,Shen's scheme improves the mean rain-rate simulation significantly through the dramatic decrease in depositional growth of cloud ice from cloud water. Compared to other schemes, Shen's scheme produces the better rainfall simulation via the reduction in the mean rain rate associated with the enhanced gain of cloud water and ice.
基金provided by National Science Foundation Awards #1560939 and #1541025
文摘A major challenge in enhancing the resilience of communities stems from current approaches used to identify needs and strategies that build the capacity of jurisdictions to mitigate loss and improve recovery. A new generation of resilience-based planning processes has emerged in the last several years that integrate goals of community well-being and identity into recovery-based performance measurement frameworks. Specific tools and refined guidance are needed to facilitate evidence-based development of recovery estimates. This article presents the participatory modeling process, a planning system designed to develop recovery-based resilience measurement frameworks for community resilience planning initiatives. Stakeholder engagement is infused throughout the participatory modeling process by integrating disaster recovery simulation modeling into community resilience planning. Within the process, participants get a unique opportunity to work together to deliberate on community concerns through facilitated participatory modeling. The participatory modeling platform combines the DESaster recovery simulation model and visual analytics interfaces.DESaster is an open source Python Library for creating discrete event simulations of disaster recovery. The simulation model was developed using a human-centered design approach whose goal is to be open, modular, and extensible. The process presented in this article is the first participatory modeling approach for analyzing recovery to aid creation of community resilience measurement frameworks.
文摘Restoring lifeline services to an urban neighborhood impacted by a large disaster is critical to the recovery of the city as a whole.Since cities are comprised of many dependent lifeline systems,the pattern of the restoration of each lifeline system can have an impact on one or more others.Due to the often uncertain and complex interactions between dense lifeline systems and their individual operations at the urban scale,it is typically unclear how different patterns of restoration will impact the overall recovery of lifeline system functioning.A difficulty in addressing this problem is the siloed nature of the knowledge and operations of different types of lifelines.Here,a city-wide,multi-lifeline restoration model and simulation are provided to address this issue.The approach uses the Graph Model for Operational Resilience,a data-driven discrete event simulator that can model the spatial and functional cascade of hazard effects and the pattern of restoration over time.A novel case study model of the District of North Vancouver is constructed and simulated for a reference magnitude 7.3 earthquake.The model comprises municipal water and wastewater,power distribution,and transport systems.The model includes 1725 entities from within these sectors,connected through 6456 dependency relationships.Simulation of the model shows that water distribution and wastewater treatment systems recover more quickly and with less uncertainty than electric power and road networks.Understanding this uncertainty will provide the opportunity to improve data collection,modeling,and collaboration with stakeholders in the future.
基金supported by research funds from Shanghai’s 2020 Annual Science and Technology Innovation Action Plan:Social development and Science&Technology Project(No.20dz1205302).
文摘Recovery of waste heat from boiler flue gas is an effective way to improve energy utilization efficiency.Taking a heating station heating project as an example,the existing heating system of this heating station was analyzed for its underutilized flue gas waste heat and low energy utilization rate.Rankine cycle is an effective waste heat recovery method,and a steam boiler organic Rankine cycle(ORC)cogeneration waste heat utilization method is proposed.The system model simulation is constructed and verified.First,a thermodynamic model was constructed in MATLAB and five suitable work gases were selected to analyze the effects of evaporation temperature and condensation temperature on the network and thermal efficiency of the waste heat cycle power system.Secondly,the ORC model is invoked in TRNSYS to construct the improved cogeneration system,and the rationality of the remaining heat utilization methods is determined by calculating and analyzing the thermal performance,economy,and environmental protection of the improved system.The simulation results show that the system can generate about 552,000 kWh of electricity per year,and improving the energy utilization rate from 0.72 to 0.78.
文摘Ground-coupled heat pumps(GCHP)are commonly used in residential heating system.To mitigate the boreholes temperature dropping with operating time,a new exhaust-air recharging system is developed.The new recharging system can be used in three operational modes.In this paper,a ground-coupled heat recovery ventilation(HRV)model is discussed.A thermal model is set up to find the optimal brine flow rate and heat transfer allocation ratio between exhaust and supply coils for maximum heat recovery efficiency.Contrary to the conventional liquid-loop HRV systems,the brine temperature entering the exhaust coil never goes blow zero(0℃),and hence defrosting is needless in the ground-coupled HRV system.This can make the ground-coupled HRV system over 20% more efficient than a conventional HRV system at low outdoor temperatures.
基金supported by the National Natural Science Foundation of China under Grant Nos.11471051 and 11871010supported by the National Social Science Foundation of China under Grant No.16ZDA033
文摘This paper considers an improved model of pricing defaultable bonds under the assumption that the interest rate satisfies the Vasicek model driven by fractional Brownian motion(fBm for short)based on the counterparty risk framework of Jarrow and Yu(2001). The authors use the theory of stochastic analysis of f Bm to derive pricing formulas for the defaultable bonds and study how the counterparty risk, recovery rate, and the Hurst parameter affect the values of the defaultable bonds.Numerical experiment results are presented to demonstrate the findings.
基金Supported by the Doctoral Foundation of the Education Commission of China.
文摘A generalized rate model for free radical copolymerization was proposed. It can be applied not only to the system with the participation of charge-transfer complex (CTC), but also to the system without the participation of CTC. The effects of equilibrium constant, total monomer concentration, homo-propagation parameters and reactivity ratios on free monomer, CTC, overall rates, and the contribution of CTC were considered in the simulation. North equation of copolymerization rate as a special case can be derived from the generalized model.
文摘Optimum utilization of the loading capability of engineering materials is an important and active contribution to protect nature's limited resources,and it is the key for economic design methods.In order to make use of the materials' resources,those must be known very well;but conventional test methods will offer only limited informational value.The range of questions raised is as wide as the application of engineering materials,and partially they are very specific.The development of huge computer powers enables numeric modelling to simulate structural behaviour in rather complex loading environments-so the real material behaviour is known under the given loading conditions.Here the art of material testing design starts.To study the material behaviour under very distinct and specific loading conditions makes it necessary to simulate different temperature ranges,loading speeds, environments etc.and mostly there doesn't exist any commonly agreed test standard.In this contribution two popular,non-standard test procedures and test systems will be discussed on the base of their application background,special design features as well as test results and typically gained information:The demand for highspeed tests up to 1000 s^(-1) of strain rate is very specific and originates primarily in the automotive industry and the answers enable CAE analysis of crashworthiness of vehicle structures under crash conditions.The information on the material behaviour under multiaxial loading conditions is a more general one.Multiaxial stress states can be reduced to an equivalent stress,which allows the evaluation of the material's constraint and criticality of stress state.Both discussed examples shall show that the open dialogue between the user and the producer of testing machines allows custom-tailored test solutions.
文摘Modeling, simulation, and prediction of global energy indices remain veritable tools for econometric, engineering, analysis, and prediction of energy indices. Thus, this paper differentially modeled, simulated, and non-differentially predicated the global energy indices. The state-of-the-art of the research includes normalization of energy indices, generation of differential rate terms, and regression of rate terms against energy indices to generate coefficients and unexplained terms. On imposition of initial conditions, the solution to the system of linear differential equations was realized in a Matlab environment. There was a strong agreement between the simulated and the field data. The exact solutions are ideal for interpolative prediction of historic data. Furthermore, the simulated data were upgraded for extrapolative prediction of energy indices by introducing an innovative model, which is the synergy of deflated and inflated prediction factors. The innovative model yielded a trendy prediction data for energy consumption, gross domestic product, carbon dioxide emission and human development index. However, the oil price was untrendy, which could be attributed to odd circumstances. Moreover, the sensitivity of the differential rate terms was instrumental in discovering the overwhelming effect of independent indices on the dependent index. Clearly, this paper has accomplished interpolative and extrapolative prediction of energy indices and equally recommends for further investigation of the untrendy nature of oil price.
基金the National Natural Science Foundation of China(Nos.52322603 and 51976005)the Science Center for Gas Turbine Project,China(Nos.P2022-B-II-004-001 and P2023-B-II-001-001)the Fundamental Research Funds for the Central Universities,and Beijing Nova Program,China(Nos.20220484074 and 20230484479).
文摘Accurate prediction of the aerodynamic response of a compressor under inlet distortion is crucial for next-generation civil aircraft,such as Boundary Layer Ingestion(BLI)silent aircraft.Therefore,research on the Body Force(BF)model plays a significant role in achieving this objective.However,distorted inlet airflow can lead to varying operating conditions across different spatial locations of the compressor,which may cause some regions to operate outside the stability boundary.Consequently,the accuracy of BF model simulations might be compromised.To address this issue,this paper proposes a numerical simulation strategy for acquiring the steady axisymmetric three-dimensional flow field of a compressor operating at low mass flow rates,which is known as the Underlying Axisymmetric Pressure Rise Characteristic(UAPRC).The proposed simulation accounts for two different rotor speeds of a transonic compressor and identifies initial positions in the flow field where deterioration occurs based on prior experimental investigations.Moreover,simulation results are incorporated into the BF model to replicate hub instability observed in experiments.Obtained results demonstrate that this strategy provides valid predictions of the UAPRC of the compressor,thereby addressing the limitations associated with the BF model.
文摘A non-equilibrium chromatographic rate model was employed to simulate the affinity chromatography of urokinase. The chromatography process was developed to a yield of high purity product of urokinase from crude materials. The affinity gel used in the process was prepared by an epichlorohydrin-activation method using epichlorohydrin activated Sepharose 4B as a matrix and p-aminobenzamidine as a ligand. The chromatographic process were numerically simulated and analyzed with the aid of VERSE-LC computer simulator. Considering the basic principles, rate model with the back mixing in column inlet was utilized in simulating and studying the effect of the column inlet pattern on other parameters. Comparison of the simulation results with the experimental data showed that the rate model can be used to describe the affinity chromatography of urokinase in a fixed bed column with satisfactory accuracy.
基金supported by the National Natural Science Foundation project“Micro-Scale Effect of Oil-Gas Flow and the Mechanism of Enhancing Shale Oil Recovery by Natural Gas Injection”(No.52074317)。
文摘Oilfields worldwide are increasingly grappling with challenges such as early water breakthrough and high water production,yet direct,targeted solutions remain elusive.In recent years,chemical flooding techniques designed for tertiary oil recovery have garnered significant attention,with microgel flooding emerging as a particularly prominent area of research.Despite its promise,the complex mechanisms underlying microgel flooding have been rarely investigated numerically.This study aims to address these gaps by characterizing the distribution of microgel concentration and viscosity within different pore structures.To enhance the accuracy of these characterizations,the viscosity of microgels is adjusted to account for the shear effects induced by flow rate and the swelling effects driven by salinity variations.The absolute permeability of the rock and the relative permeability of both oil and microgel are also analyzed to elucidate the mechanisms of microgel flooding.Additionally,a connectivity model is employed to achieve a quantitative representation of fluid flow capacity.The proposed model is validated through conceptual examples and applied to real oilfield blocks,demonstrating its accuracy and practical applicability.
文摘在“双碳”目标背景下,为推动CO_(2)驱气提高采收率技术发展,明确注气提高采收率关键参数,模拟研究基于长岩心驱替实验,通过拟合实验数据建立数值模拟模型,系统研究了注气时机、注气速度、束缚水饱和度以及开发方式等关键参数对采收率的影响。研究结果表明:①裂缝性气藏中裂缝是主要渗流通道,注入气体驱替天然气过程分为未突破和突破两阶段,未突破阶段持续时间越长,采收率越高;②提高转注压力可以增强气体驱替能力、延迟CO_(2)突破,对提高天然气采收率和CO_(2)埋存率有积极影响;③注气速度越快,气体波及范围越大,CH_(4)采收率越高,但CO_(2)埋存率降低;④束缚水饱和度对采收率和埋存率具有一定影响,束缚水饱和度增加,CH_(4)采收率提高,CO_(2)埋存率降低;⑤提前注气增压可缩短开采时间并提升CH_(4)采收率,但会降低CO_(2)埋存率。结论认为,本次模拟研究成果为优化CO_(2)-EGR(enhanced gas recovery)技术参数、降低成本、提高经济效益提供了理论依据,对推动天然气资源高效开发和实现碳减排具有重要意义。
基金Natural Science Foundation of China (Grant No. 39900084)
文摘Basic structure and algorithm of leaf mechanism photosynthesis model were described in first part of this study based on former researcher results. Then, considering some environmental factors influencing on leaf photosynthesis, three numerical sensitivity experiments were carried out. We simulated the sing le leaf net CO2 assimilation, which acts as a function of different light, carbo n dioxide and temperature conditions. The relationships between leaf net photosy nthetic rate of C3 and C4 plant with CO2 concentration intercellular, leaf tempe rature, and photosynthetic active radiation (PAR) were presented, respectively. The results show the numerical experiment may indicate the main characteristic o f plant photosynthesis in C3 and C4 plant, and further can be used to integrate with the regional climate model and act as land surface process scheme, and bett er understand the interaction between vegetation and atmosphere.
