Integrated Modeling Method Research Articles

Integrated modeling method of Cyber physical system based on extended AADL

The concept and connotation of CPS are analyzed firstly in the paper, then the challenges of system modeling brought by heterogeneous feature of the CPS system are pointed out. How to describe the CPS model are studied. We propose a description method of CPS integrated modeling framework based on extended AADL (architecture analysis and design language); and realize the unified description of the computing entity, the physical entity and interactive entity through extending the standard and appendix of AADL.

An integrated modeling method for collaborative vehicle routing: Facilitating the unmanned micro warehouse pattern in new retail

This study focuses on horizontal collaboration and addresses a collaborative multi-center vehicle routing problem (CMCVRP) deriving from the unmanned micro warehouse pattern in new retail in China. In the CMCVRP, suppliers form a coalition to reduce their operating costs and improve service levels. Traditional approaches cannot coordinate the interests of all decision subjects in this process. To fill this gap, an integrated modeling method is proposed considering the objectives at both coalition and partner levels. In the model, two constraints are presented to guarantee the interests of all decision subjects. The constraint at the coalition level defines the acceptable region of solutions to ensure the efficiency of the coalition. And the constraint at the partner level limits the difference among partners' benefits to avoid excessive profit imbalance in the alliance. After that, a metaheuristic algorithm called the non-dominated sorting genetic algorithm-large neighborhood search is proposed to solve the model. Numerical experiments are conducted on thirty instances with three kinds of logistics networks, and the integrated method is compared with an existing approach (centralized method). The results show that the integrated method has a better performance to coordinate the benefits of all decision-makers when forming the coalition than the centralized method. Also, the impact of the network structures in the collaboration on the performance of the integrated method is investigated, and the conclusions can provide guidance for suppliers to choose their cooperators.

Integrated modelling and simulation method of a cargo door actuator

An integrated Matlab model comprising of an electro-mechanical actuator (EMA) model, load model and state model has been constructed to investigate the cargo door actuator motion control, operation and working states, of which, a Simulink® servomotor system model is adopted to mimic the EMA actuator, a SimMechanics® model is used to compute the actuator's load, a Stateflow® state transition model is employed to simulate the working process. The results indicated that the motion is well controlled, generated load force is valid, working states and their transition logics are reasonable. The simulation verified the effectiveness and easiness of the integrated modelling method.

Coupled modeling of combustion and heat transfer process of a supercritical CO2 boiler

In this paper, the heat transfer process of high temperature heating surfaces in a 20 MWth supercritical CO2 (S-CO2) boiler is integrally modeled by combining the one dimensional (1D) analytical model for supercritical CO2 and the three dimensional (3D) CFD model for combustion and heat transfer process of flue gas. The 20 MWth S-CO2 boiler is designed for a 5 MWe S-CO2 power generation platform being constructed by Xi'an Thermal Power Research Institute Co., Ltd. The numerical results indicate that the tube wall temperature of gas cooling wall increases gradually along the S-CO2 flow direction, and the maximum wall temperature appears at the outlet region of the Front wall where the temperature reaches 907 K. The maximum temperature of tube wall in superheater and re-heater is around 950 K. The heat flux and temperature distributions of tube walls in superheater and re-heater are extremely non-uniform, which makes the traditional design method not practical in designing S-CO2 serpentine heat exchangers. The integral modeling method put forward in this work has the ability to capture the non-uniform heat transfer process in superheater and re-heater, and hence it is an efficient tool to study the sophisticated phenomena in S-CO2 boiler.

Spatial dynamic modelling for urban scenario planning: A case study of Nanjing, China

Although urban scenario planning is widely applied for exploring various directions of urban development, it often has high requirements on the medium of quantitative information analysis and transformation. Thus, this study establishes a method of combining scenario planning with a spatial dynamic planning support system to predict urban growth. Specifically, a scenario-based spatial dynamic modelling method is integrated with the information module of planning policy for better decision support. The integrated modelling method is applied for an actual urban land use planning case of Nanjing, an evolving city in China. The spatial forms of future urban land use are simulated under four different pre-set policy scenarios. The differences in simulated results under multi-criteria restrictions reveal the effectiveness and practical value of the integration approach. The findings of this study provide policymakers with a process-based approach to test and evaluate ‘what-if’ consequences and help stakeholders reach consensus.

Modelling Groundwater Returns to Streams From Irrigation Areas with Perched Water Tables

Quantifying the magnitude and timing of groundwater returns to streams from irrigation is important for the management of natural resources in irrigation districts where the quantity or quality of surface water can be affected. Deep vadose zones and perched water tables can complicate the modelling of these fluxes, and model outputs may be biased if these factors are misrepresented or ignored. This study was undertaken in the Murray Basin in southern Australia to develop and test an integrated modelling method that links irrigation activity to surface water impacts by accounting for all key hydrological processes, including perching and vadose zone transmission. The method incorporates an agronomic water balance to simulate root zone processes, semi-analytical transfer functions to simulate the deeper vadose zone, and an existing numerical groundwater model to simulate irrigation returns to the Murray River and inform the management of river salinity. The integrated modelling can be calibrated by various means, depending on context, and has been shown to be beneficial for management purposes without introducing an unnecessary level of complexity to traditional modelling workflows. Its applicability to other irrigation settings is discussed.

Risk and Cost Assessment of Nitrate Contamination in Domestic Wells

This study combines empirical predictive and economics models to estimate the cost of remediation for domestic wells exceeding suggested treatment thresholds for nitrates. A multiple logistic regression model predicted the probability of well contamination by nitrate, and a life cycle costing methodology was used to estimate costs of nitrate contamination in groundwater in two areas of Nebraska. In south-central Nebraska, 37% of wells were estimated to be at risk of exceeding a threshold of 7.5 mg/L as N, and 17% were at risk of exceeding 10 mg/L as N, the legal limit for human consumption in the United States. In an area in northeastern Nebraska, 82% of wells were at risk of exceeding the 10 mg/L as N legal threshold. Reverse osmosis Point-of-Use (POU) treatment was the option with the lowest costs for a household (3–4 individuals), with an average of $4–$164 total regional cost per household per year depending on the threshold for treatment. Ion exchange and distillation were the next most cost-effective options. At the community level (~10,000 individuals), a reverse osmosis Point-of-Entry (POE) treatment system was the most expensive option for a community due to high initial costs and ongoing operation and maintenance costs, whereas the biological denitrification system was least expensive due to economies of scale. This study demonstrates integrated modeling methods to assess water treatment costs over time associated with groundwater nitrate contamination, including quantification of at-risk wells, and identifies suitable options for treatment systems for rural households and communities based on their cost.

Integrated agile observation satellite scheduling problem considering different memory environments: a case study

This paper presents an experimental study on an integrated agile earth observation satellite (AEOS) scheduling problem involving the satellite memory environments of the partially erasable memory (PEM) and the holistically erasable memory (HEM). The integrated AEOS scheduling problem simultaneously considers the satellite observation and transmission events, in which the onboard memory functions as a very important connective resource. To address the memory constraints in the AEOS scheduling problem, an integrated AEOS scheduling model that is suitable for both the PEM and HEM environments is proposed in this paper. Based on commonly used construction heuristic and meta-heuristics, two hybrid approaches, Tabu-simulated annealing (TSA) and Tabu late acceptance (TLA) algorithms, are adopted to solve this problem. The highlights in this paper are the formulation of novel adaptive memory constraints for the AEOS scheduling and the quantitatively scheduling comparison of separated and integrated modeling methods. Experimental results indicate that (1) the memory environment has a direct influence on the AEOS integrated scheduling results, where the PEM environment sufficiently utilizes memory resources and advances the efficiency of the AEOS a lot. (2) The integrated scheduling method enables the reduction in resource consumption and obtains a better result than the separated scheduling method, especially in the HEM environment, (3) and the hybrid meta-heuristics TLA and TSA that show better overall performance are suggested for addressing the studied AEOS integrated scheduling problem.

Multi-objective optimization of a double-sided air-cored tubular generator based on a new integrated modeling method

Multi-objective optimization of a double-sided air-cored tubular generator based on a new integrated modeling method

Teamwork-oriented integrated modeling method for geo-problem solving

Currently, studies on constructing integrated modeling solutions in a web-based environment primarily focus on the chaining of different model-services, while the flow of exploring solutions for complex geo-problems – geographically distributed issues – has been less studied. To address this gap, a teamwork-oriented integrated modeling approach to supporting geo-problem solving based on the collaborative work of different modelers is proposed in this article, with a workflow from conceptual, logical, and finally, computational modeling. In this approach, conceptual, logical and computational models are discussed and constructed using a graph-based method, a flowchart-based method and a service-configuration-based method, respectively. By building the corresponding repositories for managing and comparing different versions of conceptual-logical-computational models, dispersed modelers can propose their own ideas and explore appropriate solutions based on existing modeling resources. A prototype modeling system was established, and two experimental modeling cases were conducted to verify the feasibility and capability of the proposed approach.

Mission success evaluation of repairable phased-mission systems with spare parts

Mission success is an important criterion to measure the performance of phased-mission systems, which is the ability of systems to finish the work successfully. Activating the spare parts takes little time, which can reduce the maintenance time while performing the mission. Moreover, adding the spare parts also can ensure the mission to complete with higher success probability. This paper puts forward an integrated modeling method to evaluate the mission success probability for repairable phased-mission systems with spare parts. Some illustrative examples are introduced to verify the flexibility and effectiveness of the proposed approach with different cases. Based on the state analysis of the component group, the risk ranking of component groups or mission phases is discussed to improve the mission success probability effectively. After analyzing the effect of spare parts on mission success probability, the optimal spare parts allocation method is proposed to obtain a cost-effective solution with the maximum mission success probability.

Operation strategy of public building: Implications from trade-off between carbon emission and occupant satisfaction

Large amount of energy is consumed to meet user satisfaction in public buildings, which causes carbon emission and results in environmental problem. A direct method to reduce this carbon emission is restricting opening area in public buildings. However, restricting opening area causes occupant satisfaction reduction. Trade-off carbon emission and occupant satisfaction needs to be concerned in building operation strategy design. In this paper, we developed a new integrated modelling method to trade-off between the carbon emission and occupant satisfaction of restriction strategies. We designed a case study in the sixth teaching building (STB) in Tsinghua University. Survey and field investigation were conducted to obtain data and build model. Integrated model result showed that satisfaction increases with the increase of carbon emission, while there exists cluster division and marginal diminishing patterns. By analyzing the performance of strategies with different calculation methods, we found that most optimal strategies open section B and C in STB. Meanwhile, when occupant number is 1,000, 2000 and 4,000, corresponding average satisfaction is 71.4%, 58.8% and 40.4%. It indicates that optimal operation strategy performance changes with the increase of occupant number, but the fluctuation is relatively mild. This integrated model has prospect in guiding energy conservation operation strategy design. It also supports real time monitoring and has potential in interactive platform application.

Communication Analysis of Network-Centric Warfare via Transformation of System of Systems Model into Integrated System Model Using Neural Network

Communication system in the network-centric warfare (NCW) has been analyzed from the perspective of the system of systems (SoS), which consists of a combat system and a network system so that the two reflect each other’s effects. However, this paradoxically causes a prolonged execution time. To solve this problem, this paper proposes an advanced integrated modeling method for the communication analysis in the NCW via the transformation of the SoS, which reduces the simulation execution time while ensuring the accuracy of the communication effects. The proposed models mainly cover interentity traffic and intraentity mobility developed in the form of feed-forward neural networks to guarantee two-way interactions between the combat system and the network system. Because they are characterized as discrete events, the proposed models are designed with the discrete-event system specification (DEVS) formalism. The experimental results show that the proposed transformation reduced an error by 6.40% compared to the existing method and reduced the execution time 3.78-fold compared to the SoS-based NCW simulation.

Electromechanical integrated modeling and analysis for the direct-driven feed system in machine tools

The permanent magnet linear synchronous motor (PMLSM) feed system realizes the direct drive. All the intermediate mechanical transmission parts are canceled and then the motor mover is directly connected with the driven components. The interaction between servo system and mechanical system becomes more close and complex, affecting the dynamic performance of the direct-driven feed system. In this paper, the dynamic characteristics of the drive circuit, PMLSM, control loops, and mechanical system are analyzed, and then an electromechanical integrated modeling method for the direct-driven feed system is proposed. Firstly, the dynamic precision of the feed system and electromechanical analytical model is studied. Then the nonlinearities of the drive circuit and PMLSM are researched. The analytical expression of the motor thrust is derived. What is more, the mechanical dynamic model is set up using the Lagrange equation and the main forms of the vibrations are discussed. Finally, the electromechanical integrated model is established and the experiments are carried out to verify the theoretical results. The results show that the proposed integrated modeling method can accurately represent the dynamic precision of the direct-driven feed system, which can provide the theoretical foundation for analyzing the electromechanical couplings and compensation methods.

Integrated modeling of coking flue gas indices based on mechanism model and improved neural network

Focusing on the first domestic coking flue gas desulfurization and denitration integrated unit in China, the current condition of inlet flue gas indices cannot be determined timely owing to the large detection lag and complex upstream coking process, which is extremely unfavorable for the optimal control of desulfurization and denitration process. In order to solve this problem, an intelligent integrated modeling method of flue gas SO2 concentration, O2 content and NOx concentration is proposed. Firstly, the gas flow diagram in combustion process is built, the mechanism models of SO2, NOx concentration and O2 content are established according to the principle of material balance and reaction kinetics, respectively. Then the RBF neural network is adopted to compensate the prediction error, an improved training algorithm combining optimal stopping principle and dual momentum adaptive learning rate is proposed to improve the training speed and generalization ability of neural network. Based on the practical data of two 55-hole and 6-meter top charging coke ovens in the coking group, the effectiveness and superiority of proposed model and method are verified by simulation via comparison of various methods.

Integrating two-temperature and classical heat accumulation models to predict femtosecond laser processing of silicon

A robust, computationally efficient modeling method describing multi-pulse femtosecond laser-material interaction is required to determine the optimal laser parameters to control and differentiate non-thermal ablation and heat accumulation processes for surface structuring and laser welding applications. We establish a three-dimensional, two-temperature model (TTM) and a heat-accumulation model based on classical heat generation and conduction equations to evaluate their efficacy and efficiency in simulating non-thermal ablation and heat accumulation during multi-pulse femtosecond laser processing of silicon. Only the TTM is capable of accurately predicting the laser fluences required to achieve non-thermal ablation, which is experimentally validated. Both the TTM and the classical heat accumulation model can predict heat accumulation. The TTM can accurately predict heat accumulation, but requires lengthy simulation times on the order of several hours. The classical heat accumulation model consistently predicts heat accumulation with the TTM and is time efficient, but is case specific to interaction parameters, requiring input of an experimentally-determined absorption coefficient. For the first time to our knowledge, an integrated modeling method is devised to accurately and efficiently simulate laser-processing-induced heat accumulation by using the TTM to determine an absorption coefficient to feed back to the heat accumulation model to extend it to the general case. This integrated modeling method enables the accurate prediction of heat accumulation with simulation times on the order of a minute per pulse, defining a path to determine laser parameters to control heat accumulation for specific processing applications.

Assessing cumulative impacts of the proposed Lower Mekong Basin hydropower cascade on the Mekong River floodplains and Delta – Overview of integrated modeling methods and results

Approach, methods, and results from a comprehensive integrated water resources modeling framework for the Lower Mekong Basin (LMB) are presented in this paper. The modeling suite was specifically tailored to the known conditions and data availability at key locations within the LMB and more particularly within the floodplains of Cambodia and the Mekong River Delta of Vietnam. Model simulation output was used to project cumulative changes to hydraulic, sediment, and water quality parameters likely to occur in this relatively unique system under multiple scenarios of hydropower development in the LMB. While substantial changes in river flow regimes are predicted as a result of hydropeaking operations especially when combined with dry-season drawdowns to maximize power production, the multiple-scenario analysis indicated that overall, the largest changes are expected to be in loss of sediment and nutrient transport and reduction of water quality due to increased salinity intrusion into areas of the Mekong Delta.

An Integrated Product-Process Hierarchical Modeling Method for Development of Complex Assembly Manufacturing Systems

The development of assembly manufacturing systems of complex products, such as automotive vehicles, needs systematic approaches. This paper proposes a new development method based on hierarchical modeling of a complex product and its assembly processes. The method integrates product and process for assembly system development by decomposing a complex product according to its hierarchical architecture in a product domain and creating the respective assembly flows in a process domain. Based on the integrated product-process hierarchical model, this paper presents three steps of manufacturing system development: 1) to plan overall assembly system flow, 2) to configure subassembly lines, and 3) to design the functionality and processes of main assembly workstations. The paper demonstrates and discusses the first two steps of assembly system development with examples. This method can make assembly manufacturing development more systematic, standardized, and efficient. The method also promotes product design variety and modularity for DFM.

Cross-layer control of wireless sensor network for smart distribution grid

This paper presents an integrated modelling method to provide cross-layer control algorithm for wireless sensor network (WSN) suited to smart distribution grid communication. The proposed algorithm is designed for improving the quality of service (QoS) of WSN communication. The cross-layer control algorithm is established, by sharing information from different protocol layers. The state parameters of different protocol layers are transformed into the corresponding concept nodes of the fuzzy cognitive map (FCM). Influence coefficients representing the subordinate relationships of different protocol layers are obtained according to state information in the previous moment. The control program is automatically set and completed by embedding FCM into WSN communication system. The proposed algorithm has been experimentally implemented and evaluated on a tested WSN with 1 coordinator node and 10 terminal/routing nodes. Experimental results show that the proposed control scheme ensures the requirements of real-time and reliability for smart distribution grid communication.

Cross-layer control of wireless sensor network for smart distribution grid

This paper presents an integrated modelling method to provide cross-layer control algorithm for wireless sensor network (WSN) suited to smart distribution grid communication. The proposed algorithm is designed for improving the quality of service (QoS) of WSN communication. The cross-layer control algorithm is established, by sharing information from different protocol layers. The state parameters of different protocol layers are transformed into the corresponding concept nodes of the fuzzy cognitive map (FCM). Influence coefficients representing the subordinate relationships of different protocol layers are obtained according to state information in the previous moment. The control program is automatically set and completed by embedding FCM into WSN communication system. The proposed algorithm has been experimentally implemented and evaluated on a tested WSN with 1 coordinator node and 10 terminal/routing nodes. Experimental results show that the proposed control scheme ensures the requirements of real-time and reliability for smart distribution grid communication.