Many organizations are struggling to provide high bandwidth and reliable internet connectivity at their branch offices and business locations and getting the most out of their operational expense.The need for internet...Many organizations are struggling to provide high bandwidth and reliable internet connectivity at their branch offices and business locations and getting the most out of their operational expense.The need for internet connectivity at any branch offices and business locations is not a luxury anymore but is a necessity.Let us try to understand how to plan and document the SDWAN(Software Defined-Wide Area Network)implementation in an organization.We will try to understand why it is essential to implement the new technology instead of investing in the existing MPLS(Multi-Protocol label switching)by taking an example of a retail organization.Methods:This project/research was performed using the abilities of Software Defined Network Technology and options available in MPLS(Multi-Protocol Label Switching).The Technical Project management principles were adopted as per PMI(Project Management Institute)waterfall methodology.Results/Conclusion:SDWAN technology provides an effective replacement of MPLS network connection for providing WAN connectivity for our office locations.It is essential to follow a documented process for appropriate vendor selection based on the available features and other listed attributes in the article.To be successful in the implementation it is essential to perform a POC(Proof of Concept)in a controlled environment and validate results.SDWAN provides better network performance and improves reliability as the links operate in active-active function.展开更多
Since the reform and opening up, China's economic level has gradually improved, and people’s demand for a better life has become increasingly strong. With the rapid development of urbanization, large-scale popula...Since the reform and opening up, China's economic level has gradually improved, and people’s demand for a better life has become increasingly strong. With the rapid development of urbanization, large-scale population and construction facilities gather in the city. Heat energy is an essential energy in people’s life. Central heating engineering has become an essential infrastructure in urban construction. At the same time, heating engineering also implements the strategy of human sustainable development, which is important for improving people’s living standards, protecting the environment and improving the environment. The present situation of gas reservoir plays an important role. The construction of heat pipe network in the city is relatively strict. In order to avoid that the heat pipe network project will affect the interests of residents, public safety and the stability of the whole system due to quality problems, the relevant parties of the project should conduct real-time supervision and inspection according to relevant standards during the construction of facilities. The design documents should be implemented to ensure the scientificity, safety and stability of the project. And improve the efficiency of its system operation, to achieve the purpose of economic operation. This paper makes a detailed analysis and discussion on the importance of the safety construction of the heat pipe network project and the supervision in the construction process, so as to lay a theoretical foundation for the smooth progress of the project.展开更多
At present, in the municipal drainage pipe network project, the level of the construction quality of the project whether to play an important correlation. Municipal drainage pipe network engineering in the actual cons...At present, in the municipal drainage pipe network project, the level of the construction quality of the project whether to play an important correlation. Municipal drainage pipe network engineering in the actual construction, should be closely around the quality control of scientific and reasonable control, take targeted means to increase the quality control, understand the main factors affecting the quality of engineering, develop a scientific and reasonable construction means, to promote the project can play a due value. This paper explores the quality control of such projects.展开更多
The brain exhibits complex physiology characterized by unique features such as a brain-specific extracellular matrix, compartmentalized structure (white and grey matter), and an aligned axonal network. These physiolog...The brain exhibits complex physiology characterized by unique features such as a brain-specific extracellular matrix, compartmentalized structure (white and grey matter), and an aligned axonal network. These physiological characteristics underpin brain function and facilitate signal transduction similar to that in an electrical circuit. Therefore, investigating these features in vitro is crucial for understanding the interactions between neuronal signal transduction processes and the pathology of neurological diseases. Compared to neurons on patterned substrates, three-dimensional (3D) bioprinting-based neural models provide significant advantages in replicating axonal kinetics without physical limitations. This study proposes the development of a 3D bioprinted engineered neural network (BENN) model to replicate the physiological features of the brain, suggesting its application as a tool for studying neurodegenerative diseases. We employed 3D bioprinting to reconstruct the compartmentalized structure of the brain, and controlled the directionality of axonal growth by applying electrical stimuli to the printed neural structure for overcoming spatial constraints. The reconstructed axonal network demonstrated reliability as a neural analog, including the visualization of mature neuronal features and spontaneous calcium reactions. Furthermore, these brain-like neural network models have demonstrated usefulness for studying neurodegeneration by enabling the visualization of degenerative pathophysiology in alcohol-exposed neurons. The BENN facilitates the visualization of region-specific pathological markers in soma or axon populations, including amyloid-beta formation and axonal deformation. Overall, the BENN closely mimics brain physiology, offers insights into the dynamics of axonal networks, and can be applied to studying neurological diseases.展开更多
The treatment of a multicomponent reversible reaction network is extremely complicated because largenumber of rate constants must be precisely determined and because the calculation based on these rateconstants is ted...The treatment of a multicomponent reversible reaction network is extremely complicated because largenumber of rate constants must be precisely determined and because the calculation based on these rateconstants is tedious.In order to reduce the degrees of freedom of the process,the authors propose a methodin which the reactor and the separator are regarded as a whole.Based on this approach,an N-componentreversible reaction system can be dealt with as a two—component system.Consequently,a simple and ac-cessible way of the apparent rate determination is suggested.For fiist-order reactions,an explicit,simplifiedexpression has been derived for both lumped and distributed parameter reaction systems.展开更多
The sustainable development of Chinas social economy, the heating pipe network project has also had a great development. At present, the society gives positive encouragement and advocacy to the sustainable development...The sustainable development of Chinas social economy, the heating pipe network project has also had a great development. At present, the society gives positive encouragement and advocacy to the sustainable development of the project, and takes energy conservation and emission reduction as a very important task at present. Environmental protection has also become the primary factor of project construction. Central heating has been gradually adopted by construction workers in the heat network, mainly because central heating can greatly reduce the cost of the project. But if there is a problem in a node in the heat network, it will lead to a large area of the heat network without heating phenomenon. Therefore, due to the complex pipe network, the quality danger of heating pipe network is easy to occur in the construction process. Strengthening the construction technology is an important basis to ensure the quality.展开更多
Intake system of diesel engine is a strong nonlinear system, and it is difficult to establish accurate model of intake system; and bias fault and precision degradation fault of MAP of diesel engine can＇t be diagnosed...Intake system of diesel engine is a strong nonlinear system, and it is difficult to establish accurate model of intake system; and bias fault and precision degradation fault of MAP of diesel engine can＇t be diagnosed easily using model-based methods. Thus, a fault diagnosis method based on Elman neural network observer is proposed. By comparing simulation results of intake pressure based on BP network and Elman neural network, lower sampling error magnitude is gained using Elman neural network, and the error is less volatile. Forecast accuracy is between 0.015？0.017 5 and sample error is controlled within 0？0.07. Considering the output stability and complexity of solving comprehensively, Elman neural network with a single hidden layer and with 44 nodes is presented as intake system observer. By comparing the relations of confidence intervals of the residual value between the measured and predicted values, error variance and failures in various fault types. Then four typical MAP faults of diesel engine can be diagnosed： complete failure fault, bias fault, precision degradation fault and drift fault. The simulation results show： intake pressure is observable and selection of diagnostic strategy parameter reasonably can increase the accuracy of diagnosis;the proposed fault diagnosis method only depends on data and structural parameters of observer, not depends on the nonlinear model of air intake system. A fault diagnosis method is proposed not depending system model to observe intake pressure, and bias fault and precision degradation fault of MAP of diesel engine can be diagnosed based on residuals.展开更多
Having criticized the current architecture of Advanced Traveler Information Systems （ATISs）, this work discusses a new base of requirements to develop a new paradigm for traffic information systems. It mainly integr...Having criticized the current architecture of Advanced Traveler Information Systems （ATISs）, this work discusses a new base of requirements to develop a new paradigm for traffic information systems. It mainly integrates three dimensions within a traffic system： drivers＇ pattern of behavior and preferences, urban traffic desires, and capabilities of traffic information service providers. Based on the above, functional segments from several related backgrounds are brought together to structure a new architecture, called Interactive Traveler Information System （ITIS）. The main interactive feature of this new architecture is a two-way communication track between drivers and the traffic information system provider-in fact, a decision on choosing a road at a particular time for an individual will be made based on the utility of both sides. This new configuration consists of driver-side smartphone application, centric traffic prediction, and decision-maker units, which will shape a new approach of decision-making processes. These all work together to satisfy the designated goal of ITIS, which is preserving the Wardrop equilibrium condition in the traffic network level. Finally, we concentrate on a comparison study, which shows a differentiation between performance of the proposed ITIS and the current ATIS model in a real situation. This has been done with simulations of analogical scenarios. The most noticeable advantage of the proposed architecture is not being limited to a saturation limit, and the positive effect of increasing system penetration in the performance of the newly introduced information system. In conclusion, new research subjects are suggested to be carried out.展开更多
Software Defined Networking(SDN) provides a flexible and convenient way to support fine-grained traffic-engineering(TE). Besides, SDN also provides better Quality of Experience(QoE) for customers. However, the policy ...Software Defined Networking(SDN) provides a flexible and convenient way to support fine-grained traffic-engineering(TE). Besides, SDN also provides better Quality of Experience(QoE) for customers. However, the policy of the evolution from legacy networks to the SDNs overemphasizes the controllability of the network or TE while ignoring the customers' benefit. Standing in the customers' position, we propose an optimization scheme, named as Optimal Migration Schedule based on Customers' Benefit(OMSB), to produce an optimized migration schedule and maximize the benefit of customers. Not only the quality and quantity of paths availed by migration, but also the number of flows from the customers that can use these multi-paths are taken into consideration for the scheduling. We compare the OMSB with other six migration schemes in terms of the benefit of customers. Our results suggest that the sequence of the migration plays a vital role for customers, especially in the early stages of the network migration to the SDN.展开更多
A safe and dependable supply of energy and power is directly correlated with the quality of distribution network engineering.The assessment and diagnosis of the design quality and economic viability of a distribution ...A safe and dependable supply of energy and power is directly correlated with the quality of distribution network engineering.The assessment and diagnosis of the design quality and economic viability of a distribution network engineering process are essential for guaranteeing the steady functioning of the corresponding power system.In this paper,an intelligent assisted assessment technique for distribution network engineering is proposed to address the issues of inefficiency,high manual dependence,and low utilization of vital information in the text during the eval-uation of projects related to distribution network engi-neering.To improve the model’s contextual learning ability,the robustly optimized bidirectional encoder representa-tions from transformers pretraining approach and whole-word masking are adopted to extract useful features from the distribution network engineering project review text.Principal component analysis is then used to downscale the high-dimensional features,thereby greatly increasing the efficiency of downstream classification.The light gradient boosting machine performs classification on the downscaled text features,and the Bayesian optimiza-tion approach is utilized to identify the best hyperparame-ter combinations.This significantly lessens the impacts of random parameters on the model performance.Tenfold cross-validation results demonstrate that the model can quickly and accurately identify common problems in dis-tribution network projects’technical and economic di-mensions.展开更多
Because there is neither waste rock nor mill tailings in the gypsum mine, and the buildings on the goaf of gypsum mine are needed to be protected, the research proposed the scheme of the clay filling technology. Gypsu...Because there is neither waste rock nor mill tailings in the gypsum mine, and the buildings on the goaf of gypsum mine are needed to be protected, the research proposed the scheme of the clay filling technology. Gypsum, cement, lime and water glass were used as adhesive, and the strength of different material ratios were investigated in this study. The influence factors of clay strength were obtained in the order of cement, gypsum, water glass and lime. The results show that the cement content is the determinant influence factor, and gypsum has positive effects, while the water glass can enhance both clay strength and the fluidity of the filing slurry. Furthermore, combining chaotic optimization method with neural network, the optimal ratio of composite cementing agent was obtained. The results show that the optimal ratio of water glass, cement, lime and clay (in quality) is 1.17:6.74:4.17:87.92 in the process of bottom self-flow filling, while the optimal ratio is 1.78:9.58:4.71:83.93 for roof-contacted filling. A novel filling process to fill in gypsum mine goaf with clay is established. The engineering practice shows that the filling cost is low, thus, notable economic benefit is achieved.展开更多
The network method for modeling thermoacoustic engines is described. Some simulation results on acoustic fields and phases in engine, especially in the thermoacoustic stack are presented and analyzed. The effects of s...The network method for modeling thermoacoustic engines is described. Some simulation results on acoustic fields and phases in engine, especially in the thermoacoustic stack are presented and analyzed. The effects of some key factors on performance of stack and engine system are simulated and discussed. These effect factors include the spaces of plates of stack, the position of stack in engine system, the source parameter of stack, and the mean working pressure of the engine system.展开更多
In the present work,artificial neural networks(ANN)technique combined with flamelet generated manifolds(FGM)is proposed to mitigate the memory issue of FGM models.A set of ANN models is firstly trained using a 68-spec...In the present work,artificial neural networks(ANN)technique combined with flamelet generated manifolds(FGM)is proposed to mitigate the memory issue of FGM models.A set of ANN models is firstly trained using a 68-species mass fractions in mixture fraction-progress variable space.The ANN prediction accuracy is examined in large eddy simulation(LES)and Reynolds averaged Navier-Stokes(RANS)simulations of spray combustion.It is shown that the present ANN models can properly replicate the FGM table for most of the species mass fractions.The network models with relative error less than 5%are considered in RANS and LES to simulate the Engine Combustion Network(ECN)Spray H flames.Validation of the method is firstly conducted in the framework of RANS.Both non-reacting and reacting cases show the present method predicts very well the trend of spray and combustion process under different ambient temperatures.The results show that FGM-ANN can replicate the ignition delay time(IDT)and lift-off length(LOL)precisely as the conventional FGM method,and the results agree very well with the experiments.With the help of ANN,it is possible to achieve high efficiency and accuracy,with a significantly reduced memory requirement of the FGM models.LES with FGM-ANN is then applied to explore the detailed spray combustion process.Chemical explosive mode analysis(CEMA)approach is used to identify the local combustion modes.It is found that before the spray flame is developed to the steady-state,the high CH_(2)O zone is always associated with ignition mode.However,high CH_(2)O zone together with high OH zone is dominated by the burned mode after the steady-state.The lift-off position is dominated mainly by the diffusion mode.展开更多
文摘Many organizations are struggling to provide high bandwidth and reliable internet connectivity at their branch offices and business locations and getting the most out of their operational expense.The need for internet connectivity at any branch offices and business locations is not a luxury anymore but is a necessity.Let us try to understand how to plan and document the SDWAN(Software Defined-Wide Area Network)implementation in an organization.We will try to understand why it is essential to implement the new technology instead of investing in the existing MPLS(Multi-Protocol label switching)by taking an example of a retail organization.Methods:This project/research was performed using the abilities of Software Defined Network Technology and options available in MPLS(Multi-Protocol Label Switching).The Technical Project management principles were adopted as per PMI(Project Management Institute)waterfall methodology.Results/Conclusion:SDWAN technology provides an effective replacement of MPLS network connection for providing WAN connectivity for our office locations.It is essential to follow a documented process for appropriate vendor selection based on the available features and other listed attributes in the article.To be successful in the implementation it is essential to perform a POC(Proof of Concept)in a controlled environment and validate results.SDWAN provides better network performance and improves reliability as the links operate in active-active function.
文摘Since the reform and opening up, China's economic level has gradually improved, and people’s demand for a better life has become increasingly strong. With the rapid development of urbanization, large-scale population and construction facilities gather in the city. Heat energy is an essential energy in people’s life. Central heating engineering has become an essential infrastructure in urban construction. At the same time, heating engineering also implements the strategy of human sustainable development, which is important for improving people’s living standards, protecting the environment and improving the environment. The present situation of gas reservoir plays an important role. The construction of heat pipe network in the city is relatively strict. In order to avoid that the heat pipe network project will affect the interests of residents, public safety and the stability of the whole system due to quality problems, the relevant parties of the project should conduct real-time supervision and inspection according to relevant standards during the construction of facilities. The design documents should be implemented to ensure the scientificity, safety and stability of the project. And improve the efficiency of its system operation, to achieve the purpose of economic operation. This paper makes a detailed analysis and discussion on the importance of the safety construction of the heat pipe network project and the supervision in the construction process, so as to lay a theoretical foundation for the smooth progress of the project.
文摘At present, in the municipal drainage pipe network project, the level of the construction quality of the project whether to play an important correlation. Municipal drainage pipe network engineering in the actual construction, should be closely around the quality control of scientific and reasonable control, take targeted means to increase the quality control, understand the main factors affecting the quality of engineering, develop a scientific and reasonable construction means, to promote the project can play a due value. This paper explores the quality control of such projects.
基金supported by Korean Fund for Regenerative Medicine funded by Ministry of Science and ICT,and Ministry of Health and Welfare(22A0106L1,Republic of Korea)the National Research Foundation of Korea(NRF)grant funded by the Korea government(MSIT)(No.2022M3C1A3081359).
文摘The brain exhibits complex physiology characterized by unique features such as a brain-specific extracellular matrix, compartmentalized structure (white and grey matter), and an aligned axonal network. These physiological characteristics underpin brain function and facilitate signal transduction similar to that in an electrical circuit. Therefore, investigating these features in vitro is crucial for understanding the interactions between neuronal signal transduction processes and the pathology of neurological diseases. Compared to neurons on patterned substrates, three-dimensional (3D) bioprinting-based neural models provide significant advantages in replicating axonal kinetics without physical limitations. This study proposes the development of a 3D bioprinted engineered neural network (BENN) model to replicate the physiological features of the brain, suggesting its application as a tool for studying neurodegenerative diseases. We employed 3D bioprinting to reconstruct the compartmentalized structure of the brain, and controlled the directionality of axonal growth by applying electrical stimuli to the printed neural structure for overcoming spatial constraints. The reconstructed axonal network demonstrated reliability as a neural analog, including the visualization of mature neuronal features and spontaneous calcium reactions. Furthermore, these brain-like neural network models have demonstrated usefulness for studying neurodegeneration by enabling the visualization of degenerative pathophysiology in alcohol-exposed neurons. The BENN facilitates the visualization of region-specific pathological markers in soma or axon populations, including amyloid-beta formation and axonal deformation. Overall, the BENN closely mimics brain physiology, offers insights into the dynamics of axonal networks, and can be applied to studying neurological diseases.
文摘The treatment of a multicomponent reversible reaction network is extremely complicated because largenumber of rate constants must be precisely determined and because the calculation based on these rateconstants is tedious.In order to reduce the degrees of freedom of the process,the authors propose a methodin which the reactor and the separator are regarded as a whole.Based on this approach,an N-componentreversible reaction system can be dealt with as a two—component system.Consequently,a simple and ac-cessible way of the apparent rate determination is suggested.For fiist-order reactions,an explicit,simplifiedexpression has been derived for both lumped and distributed parameter reaction systems.
文摘The sustainable development of Chinas social economy, the heating pipe network project has also had a great development. At present, the society gives positive encouragement and advocacy to the sustainable development of the project, and takes energy conservation and emission reduction as a very important task at present. Environmental protection has also become the primary factor of project construction. Central heating has been gradually adopted by construction workers in the heat network, mainly because central heating can greatly reduce the cost of the project. But if there is a problem in a node in the heat network, it will lead to a large area of the heat network without heating phenomenon. Therefore, due to the complex pipe network, the quality danger of heating pipe network is easy to occur in the construction process. Strengthening the construction technology is an important basis to ensure the quality.
文摘Intake system of diesel engine is a strong nonlinear system, and it is difficult to establish accurate model of intake system; and bias fault and precision degradation fault of MAP of diesel engine can＇t be diagnosed easily using model-based methods. Thus, a fault diagnosis method based on Elman neural network observer is proposed. By comparing simulation results of intake pressure based on BP network and Elman neural network, lower sampling error magnitude is gained using Elman neural network, and the error is less volatile. Forecast accuracy is between 0.015？0.017 5 and sample error is controlled within 0？0.07. Considering the output stability and complexity of solving comprehensively, Elman neural network with a single hidden layer and with 44 nodes is presented as intake system observer. By comparing the relations of confidence intervals of the residual value between the measured and predicted values, error variance and failures in various fault types. Then four typical MAP faults of diesel engine can be diagnosed： complete failure fault, bias fault, precision degradation fault and drift fault. The simulation results show： intake pressure is observable and selection of diagnostic strategy parameter reasonably can increase the accuracy of diagnosis;the proposed fault diagnosis method only depends on data and structural parameters of observer, not depends on the nonlinear model of air intake system. A fault diagnosis method is proposed not depending system model to observe intake pressure, and bias fault and precision degradation fault of MAP of diesel engine can be diagnosed based on residuals.
文摘Having criticized the current architecture of Advanced Traveler Information Systems （ATISs）, this work discusses a new base of requirements to develop a new paradigm for traffic information systems. It mainly integrates three dimensions within a traffic system： drivers＇ pattern of behavior and preferences, urban traffic desires, and capabilities of traffic information service providers. Based on the above, functional segments from several related backgrounds are brought together to structure a new architecture, called Interactive Traveler Information System （ITIS）. The main interactive feature of this new architecture is a two-way communication track between drivers and the traffic information system provider-in fact, a decision on choosing a road at a particular time for an individual will be made based on the utility of both sides. This new configuration consists of driver-side smartphone application, centric traffic prediction, and decision-maker units, which will shape a new approach of decision-making processes. These all work together to satisfy the designated goal of ITIS, which is preserving the Wardrop equilibrium condition in the traffic network level. Finally, we concentrate on a comparison study, which shows a differentiation between performance of the proposed ITIS and the current ATIS model in a real situation. This has been done with simulations of analogical scenarios. The most noticeable advantage of the proposed architecture is not being limited to a saturation limit, and the positive effect of increasing system penetration in the performance of the newly introduced information system. In conclusion, new research subjects are suggested to be carried out.
基金supported by Joint Funds of National Natural Science Foundation of China and Xinjiang under code U1603261the Research Fund of Ministry of Education-China Mobile under Grant No. MCM20160304the Fundamental Research Funds for the Central Universities
文摘Software Defined Networking(SDN) provides a flexible and convenient way to support fine-grained traffic-engineering(TE). Besides, SDN also provides better Quality of Experience(QoE) for customers. However, the policy of the evolution from legacy networks to the SDNs overemphasizes the controllability of the network or TE while ignoring the customers' benefit. Standing in the customers' position, we propose an optimization scheme, named as Optimal Migration Schedule based on Customers' Benefit(OMSB), to produce an optimized migration schedule and maximize the benefit of customers. Not only the quality and quantity of paths availed by migration, but also the number of flows from the customers that can use these multi-paths are taken into consideration for the scheduling. We compare the OMSB with other six migration schemes in terms of the benefit of customers. Our results suggest that the sequence of the migration plays a vital role for customers, especially in the early stages of the network migration to the SDN.
基金supported by the Project of the National Social Science Fund of China(No.19BGL003).
文摘A safe and dependable supply of energy and power is directly correlated with the quality of distribution network engineering.The assessment and diagnosis of the design quality and economic viability of a distribution network engineering process are essential for guaranteeing the steady functioning of the corresponding power system.In this paper,an intelligent assisted assessment technique for distribution network engineering is proposed to address the issues of inefficiency,high manual dependence,and low utilization of vital information in the text during the eval-uation of projects related to distribution network engi-neering.To improve the model’s contextual learning ability,the robustly optimized bidirectional encoder representa-tions from transformers pretraining approach and whole-word masking are adopted to extract useful features from the distribution network engineering project review text.Principal component analysis is then used to downscale the high-dimensional features,thereby greatly increasing the efficiency of downstream classification.The light gradient boosting machine performs classification on the downscaled text features,and the Bayesian optimiza-tion approach is utilized to identify the best hyperparame-ter combinations.This significantly lessens the impacts of random parameters on the model performance.Tenfold cross-validation results demonstrate that the model can quickly and accurately identify common problems in dis-tribution network projects’technical and economic di-mensions.
基金supported by the National Basic Research and Development Program of China (No. 2010CB732004)the joint funding of the National Natural Science Foundation and Shanghai Baosteel Group Corporation of China (No. 51074177)
文摘Because there is neither waste rock nor mill tailings in the gypsum mine, and the buildings on the goaf of gypsum mine are needed to be protected, the research proposed the scheme of the clay filling technology. Gypsum, cement, lime and water glass were used as adhesive, and the strength of different material ratios were investigated in this study. The influence factors of clay strength were obtained in the order of cement, gypsum, water glass and lime. The results show that the cement content is the determinant influence factor, and gypsum has positive effects, while the water glass can enhance both clay strength and the fluidity of the filing slurry. Furthermore, combining chaotic optimization method with neural network, the optimal ratio of composite cementing agent was obtained. The results show that the optimal ratio of water glass, cement, lime and clay (in quality) is 1.17:6.74:4.17:87.92 in the process of bottom self-flow filling, while the optimal ratio is 1.78:9.58:4.71:83.93 for roof-contacted filling. A novel filling process to fill in gypsum mine goaf with clay is established. The engineering practice shows that the filling cost is low, thus, notable economic benefit is achieved.
基金This work was supported by the National Nature Science Foundation of China (No.59706003).
文摘The network method for modeling thermoacoustic engines is described. Some simulation results on acoustic fields and phases in engine, especially in the thermoacoustic stack are presented and analyzed. The effects of some key factors on performance of stack and engine system are simulated and discussed. These effect factors include the spaces of plates of stack, the position of stack in engine system, the source parameter of stack, and the mean working pressure of the engine system.
文摘In the present work,artificial neural networks(ANN)technique combined with flamelet generated manifolds(FGM)is proposed to mitigate the memory issue of FGM models.A set of ANN models is firstly trained using a 68-species mass fractions in mixture fraction-progress variable space.The ANN prediction accuracy is examined in large eddy simulation(LES)and Reynolds averaged Navier-Stokes(RANS)simulations of spray combustion.It is shown that the present ANN models can properly replicate the FGM table for most of the species mass fractions.The network models with relative error less than 5%are considered in RANS and LES to simulate the Engine Combustion Network(ECN)Spray H flames.Validation of the method is firstly conducted in the framework of RANS.Both non-reacting and reacting cases show the present method predicts very well the trend of spray and combustion process under different ambient temperatures.The results show that FGM-ANN can replicate the ignition delay time(IDT)and lift-off length(LOL)precisely as the conventional FGM method,and the results agree very well with the experiments.With the help of ANN,it is possible to achieve high efficiency and accuracy,with a significantly reduced memory requirement of the FGM models.LES with FGM-ANN is then applied to explore the detailed spray combustion process.Chemical explosive mode analysis(CEMA)approach is used to identify the local combustion modes.It is found that before the spray flame is developed to the steady-state,the high CH_(2)O zone is always associated with ignition mode.However,high CH_(2)O zone together with high OH zone is dominated by the burned mode after the steady-state.The lift-off position is dominated mainly by the diffusion mode.
