Gas drainage is carried out based on output from each coal bed throughout commingling production of coalbed methane(CBM).A reasonable drainage process should therefore initially guarantee main coal bed production and ...Gas drainage is carried out based on output from each coal bed throughout commingling production of coalbed methane(CBM).A reasonable drainage process should therefore initially guarantee main coal bed production and then enhance gas output from other beds.Permanent damage can result if this is not the case,especially with regard to fracture development in the main gas-producing coal bed and can greatly reduce single well output.Current theoretical models and measuring devices are inapplicable to commingled CBM drainage,however,and so large errors in predictive models cannot always be avoided.The most effective currently available method involves directly measuring gas output from each coal bed as well as determining the dominant gas-producing unit.A dynamic evaluation technique for gas output from each coal bed during commingling CBM production is therefore proposed in this study.This technique comprises a downhole measurement system combined with a theoretical calculation model.Gas output parameters(i.e.,gas-phase flow rate,temperature,pressure)are measured in this approach via a downhole measurement system;substituting these parameters into a deduced theoretical calculation model then means that gas output from each seam can be calculated to determine the main gas-producing unit.Trends in gas output from a single well or each seam can therefore be predicted.The laboratory and field test results presented here demonstrate that calculation errors in CBM outputs can be controlled within a margin of 15%and therefore conform with field use requirements.展开更多
The article establishes the appraisal index system for entire urban agglomeration and its interior cities individually,concretely including five aspects:driving forces for tourism development,the level of tourism deve...The article establishes the appraisal index system for entire urban agglomeration and its interior cities individually,concretely including five aspects:driving forces for tourism development,the level of tourism development,tourism impacts,tourism economic connection and tourism contributions of different cities to the whole urban agglomeration.As tourism competitiveness has the characteristics of comprehensiveness,systematicness and dynamicness,the article attempts to apply the structural prediction means of system dynamics to evaluating tourism competitiveness,aiming to provide some research methods and analysis ideas for tourism competitiveness measurement and trends analysis in urban agglomeration.Taking Shandong Peninsula urban agglomeration as the study area,the article simulates and analyzes the tourism competitiveness trend of the whole region and its interior cities from 2005 to 2020,and the result reflects that integrated development and regional combination of tourism are important means to upgrade tourism competitiveness in this region.展开更多
Micro-mobile heat pipe-cooled nuclear power plants are promising candidates for distributed energy resource power genera-tors and can be flexibly deployed in remote places to meet increasing electric power demands.How...Micro-mobile heat pipe-cooled nuclear power plants are promising candidates for distributed energy resource power genera-tors and can be flexibly deployed in remote places to meet increasing electric power demands.However,previous steady-state simulations and experiments have deviated significantly from actual micronuclear system operations.Hence,a transient analysis is required for performance optimization and safety assessment.In this study,a hardware-in-the-loop(HIL)approach was used to investigate the dynamic behavior of scaled-down heat pipe-cooled systems.The real-time features of the HIL architecture were interpreted and validated,and an optimal time step of 500 ms was selected for the thermal transient.The power transient was modeled using point kinetic equations,and a scaled-down thermal prototype was set up to avoid mod-eling unpredictable heat transfer behaviors and feeding temperature samples into the main program running on a desktop PC.A series of dynamic test results showed significant power and temperature oscillations during the transient process,owing to the inconsistency of the rapid nuclear reaction rate and large thermal inertia.The proposed HIL approach is stable and effective for further studying of the dynamic characteristics and control optimization of solid-state small nuclear-powered systems at an early prototyping stage.展开更多
The current method of evaluating passenger satisfaction primarily adopts the traditional static evaluation mode,which can hardly satisfy the dynamic regulatory requirements of highway passenger transport service quali...The current method of evaluating passenger satisfaction primarily adopts the traditional static evaluation mode,which can hardly satisfy the dynamic regulatory requirements of highway passenger transport service quality set by industry management departments.In this paper,we summarize the characteristics of real-time dynamic evaluation under the requirements of hierarchical and classified evaluation and analyze the entire process of the one-time travel service of highway passenger transport.We focus on station waiting and in-vehicle services,extract the elements most concerned by passengers as evaluation indexes,and construct a three-level index system.Subsequently,a multi-indicator comprehensive evaluation method based on the analytic hierarchy process and fuzzy comprehensive evaluation is selected to construct a comprehensive evaluation model.By combining with the development level of electronic ticket purchasing and the requirements of satisfaction evaluation,we propose three data collection methods and compare and analyze their strengths and weaknesses.Finally,based on actual survey data,the effectiveness of the model is verified.The verification results show that the real-time dynamic evaluation index system based on the Internet can better satisfy evaluation requirements.展开更多
Groundwater resource is vital to the sustainable development of socio-economics in arid and semi-arid regions of Northwest China. An estimation of the groundwater resources variation in Zhangye Basin was made during 1...Groundwater resource is vital to the sustainable development of socio-economics in arid and semi-arid regions of Northwest China. An estimation of the groundwater resources variation in Zhangye Basin was made during 1985-2013 based on long-term groundwater observation data and geostatistical method. The results show that from 1985 to 2013, groundwater storage exhibited tremendous dissimilarity on temporal and spatial scale for the whole Zhangye Basin, especially before and after implementation of the water diversion policy. Trend of groundwater storage varied from quick to slow decline or increase. The accumulative groundwater storage decreased nearly 47.52~ 108 m3, and annual average depletion rate reached 1.64x 108 m3/a. Among which, the accumulative groundwater storage of the river and well water mixed irrigation district decreased by 37.48x 108 m3, accounting for about 78.87% of the total groundwater depletion of the Zhangye Basin. Accumulative depletion of groundwater storage varied in respective irrigation districts. Though groundwater resources depletion rate slowed down from 2005, the overall storage in the whole basin and re- spective districts during 1985-2013 was still in a severe deficit such that, the groundwater resource was in a rather negative balance, which could threaten the local aquifer. This is the joint effect of climate change and human activities, however human activities, such as water diversion policy and groundwater exploitation, became increasingly intense. Our research results could provide a reasonable estimation for the groundwater balance in Zhangye Basin, providing a scientific basis for water resources unified planning and, this method can provide a relatively reliable way of estimation for large scale groundwater resources.展开更多
This paper presents dynamic evaluation of enterprise's strategy which is suitable for dealing with the complex and dynamic problems of strategic evaluation. Rough Set Theory is a powerful mathematical tool to hand...This paper presents dynamic evaluation of enterprise's strategy which is suitable for dealing with the complex and dynamic problems of strategic evaluation. Rough Set Theory is a powerful mathematical tool to handle vagueness and uncertainty of dynamic evaluation. By the application of Rough Set Theory, this paper computes the significance and weights of each evaluation criterion and helps to lay evaluation emphasis on the main and effective criteria. From the reduced decision table,evaluators can get decision rules Which direct them to give judgment or suggestion of strategy. The whole evaluation process is decided by data, so the results are certain and reasonable.展开更多
This paper presents an analysis of the random fluctuations, deferred conduction effect and periodicity of road traffic based on the basic features of road networks. It also discusses the limitations of road network ev...This paper presents an analysis of the random fluctuations, deferred conduction effect and periodicity of road traffic based on the basic features of road networks. It also discusses the limitations of road network evaluation theories based on road "V/C". In addition, it proposes a set of theoretical and technical methods for the real-time evaluation of traffic flows for entire road networks, and for solving key technical issues, such as real-time data collection and processing in areas with no blind zones, the spatial-temporal dynamic analysis of road network traffic, and the calibration of key performance index thresholds. It also provides new technical tools for the strategic transportation planning and real-time diagnosis of road traffic. The new tools and methodology presented in this paper are validated using a case study in Beijing.展开更多
Because the static evaluation is unable to reflect the dynamic features of economic benefits and the contribution of sustainable development of low-carbon new energy to economic benefits is huge,this article puts forw...Because the static evaluation is unable to reflect the dynamic features of economic benefits and the contribution of sustainable development of low-carbon new energy to economic benefits is huge,this article puts forward the dynamic evaluation model of economic benefits under the development of low-carbon new energy.Total energy,energy consumption structure,industrial structure,GDP,total population and energy supply structure were taken as independent variables,and the carbon intensity was taken as the dependent variable.Through t-test and decision coefficient,total energy,energy consumption structure,GDP and total population were determined as the main factors of influencing low-carbon economy.Based on these four main factors,the dynamic evaluation index system of economic benefits was constructed.Experimental results show that the proposed model can comprehensively reflect the economic benefit level and the contribution of low-carbon new energy.Therefore,this method has high evaluation accuracy,which can provide scientific reference for the economic benefit management of relevant management departments.展开更多
Oral English is an important part in higher vocational English teaching. The 2021 edition of "English Curriculum Standard for Higher Vocational Education" puts forward new requirements for higher vocational ...Oral English is an important part in higher vocational English teaching. The 2021 edition of "English Curriculum Standard for Higher Vocational Education" puts forward new requirements for higher vocational students oral English ability. The document proposes that "students can use English language knowledge and skills to accurately understand and express information, views and feelings, and communicate effectively orally and in writing." Under such requirements, the traditional final examination evaluation method cannot meet the challenges of the new era. The new evaluation method is intervention dynamic evaluation, which pays attention to the communication between teachers and students and interactive feedback, and continuously adjusts the dynamic form of teaching methods through feedback. Through the intervention dynamic evaluation experiment of oral courses, the author observes whether the new evaluation method can reduce students learning anxiety and improve learning efficiency.展开更多
Based on the value theory of mineral resource, a dynamic evaluation model of mineral resource property is erected, which not only takes the factors of extractions into consideration but also those of explorations. The...Based on the value theory of mineral resource, a dynamic evaluation model of mineral resource property is erected, which not only takes the factors of extractions into consideration but also those of explorations. The solution process of the model is described and the differential solution is presented. Then the paper comes to the conclusion that the differential solution is also the optimal depletion path of the resource.展开更多
Configuration evaluation is a key technology to be considered in the design of multiple aircrafts formation(MAF)configurations with high dynamic properties in engineering applications.This paper deduces the relationsh...Configuration evaluation is a key technology to be considered in the design of multiple aircrafts formation(MAF)configurations with high dynamic properties in engineering applications.This paper deduces the relationship between relative velocity,dynamic safety distance and dynamic adjacent distance of formation members,then divides the formation states into collision-state and matching-state.Meanwhile,probability models are constructed based on the binary normal distribution of relative distance and relative velocity.Moreover,configuration evaluation strategies are studied by quantitatively analyzing the denseness and the basic capabilities according to the MAF collision-state probability and the MAF matching-state probability,respectively.The scale of MAF is grouped into 5 levels,and previous lattice-type structures are extended into four degrees by taking the relative velocities into account to instruct the configuration design under complex task conditions.Finally,hardware-in-loop(HIL)simulation and outfield flight test results are presented to verify the feasibility of these evaluation strategies.展开更多
In the complex environment of Wireless Sensor Networks(WSNs),various malicious attacks have emerged,among which internal attacks pose particularly severe security risks.These attacks seriously threaten network stabili...In the complex environment of Wireless Sensor Networks(WSNs),various malicious attacks have emerged,among which internal attacks pose particularly severe security risks.These attacks seriously threaten network stability,data transmission reliability,and overall performance.To effectively address this issue and significantly improve intrusion detection speed,accuracy,and resistance to malicious attacks,this research designs a Three-level Intrusion Detection Model based on Dynamic Trust Evaluation(TIDM-DTE).This study conducts a detailed analysis of how different attack types impact node trust and establishes node models for data trust,communication trust,and energy consumption trust by focusing on characteristics such as continuous packet loss and energy consumption changes.By dynamically predicting node trust values using the grey Markov model,the model accurately and sensitively reflects changes in node trust levels during attacks.Additionally,DBSCAN(Density-Based Spatial Clustering of Applications with Noise)data noise monitoring technology is employed to quickly identify attacked nodes,while a trust recovery mechanism restores the trust of temporarily faulty nodes to reduce False Alarm Rate.Simulation results demonstrate that TIDM-DTE achieves high detection rates,fast detection speed,and low False Alarm Rate when identifying various network attacks,including selective forwarding attacks,Sybil attacks,switch attacks,and black hole attacks.TIDM-DTE significantly enhances network security,ensures secure and reliable data transmission,moderately improves network energy efficiency,reduces unnecessary energy consumption,and provides strong support for the stable operation of WSNs.Meanwhile,the research findings offer new ideas and methods for WSN security protection,possessing important theoretical significance and practical application value.展开更多
The economy of China has turned to the stage of high-quality development. In this sense,the connotation of regional innovation capacity should reflect more aspects, such as better economic effectiveness, people-center...The economy of China has turned to the stage of high-quality development. In this sense,the connotation of regional innovation capacity should reflect more aspects, such as better economic effectiveness, people-centered philosophy of development and better living conditions. This study aims at establishing the evaluation index system of regional innovation capacity under high-quality perspective.Then the dynamic evaluation method based on gray correlation degree and TOPSIS is improved. And the improved method is applied to evaluate the regional innovation capacity under high-quality development perspective. The results show that: 1) The regional innovation capacity of Jiangsu, Zhejiang,Shanghai and Guangdong under high-quality development perspective is better than other regions,while the regional innovation capacity of Beijing-Tianjin-Hebei is imbalanced. Regional innovation capability of Fujian, Shandong, and Hainan from a high-quality perspective is at the middle and lower levels. 2) From the perspective of development trends, the gap of regional innovation capacity between Beijing, Jiangsu, Zhejiang, Shanghai, Guangdong and Fujian, Hebei, Shandong is gradually narrowing.3) An in-depth analysis of the regional innovation capability of the eastern provinces and cities from the perspective of high-quality development through different dimensions shows that Beijing, Guangdong, Jiangsu perform well in all dimensions, while Fujian and Hainan need to pay more attention to innovation input and the creation of a better innovation environment to enhance innovation output and promote innovation effectiveness. At last, based on above analysis, relevant policy recommendations are proposed.展开更多
Currently, traditional development issues, such as economic stagnation, as well as new challenges like environmental degradation and globalization, need attention. Sustainable development, including economic, environm...Currently, traditional development issues, such as economic stagnation, as well as new challenges like environmental degradation and globalization, need attention. Sustainable development, including economic, environmental, and social elements, is a main goal of decision-makers. The key to sustainable decision-making is to evaluate and forecast the status quo of sustainable development. Policy makers need a tool based on scientific information to forecast the effects of future actions on sustainability and make policies for sustainable development. This paper analyzes the relation of the economy, environment and social welfare by the grey dynamic model. The proposed method uses time series and basic indicators of ecological system, including economic, environmental and social sub-systems. It is applied to Heilongjiang Province and Jiangsu Province. The results have proved different status quo of sustainable development in these two regions, and suggestions are proposed, such as optimization of industrial structure and eco-industrial development. The conclusion is that there is no unique sustainable path, and accordingly, policy makers should choose different criteria and strategies to make efficient sustainable decisions for each region.展开更多
The new Austrian tunneling method （NATM） is widely applied in design and construction of underground engineering projects. When the type and distribution of unfavorable geological bodies （UGBs） associated with the...The new Austrian tunneling method （NATM） is widely applied in design and construction of underground engineering projects. When the type and distribution of unfavorable geological bodies （UGBs） associated with their influences on geoengineering are complicated or unfortunately are overlooked, we should pay more attentions to internal features of rocks grades IV and V （even in local but mostly controlling zones）. With increasing attentions to the characteristics, mechanism and influences of engineering construction-triggered geohazards, it is crucial to fully understand the disturbance of these geohazards on project construction. A reasonable determination method in construction procedure, i.e. the shape of working face, the type of engineering support and the choice of feasible procedure, should be considered in order to mitigate the construction-triggered geohazards. Due to their high sensitivity to groundwater and in-situ stress, various UGBs exhibit hysteretic nature and failure modes. To give a complete understanding on the internal causes, the emphasis on advanced comprehensive geological forecasting and overall reinforcement treatment is therefore of more practical significance. Compre- hensive evaluation of influential factors, identification of UGB, and measures of discontinuity dynamic controlling comprises the geoengineering condition evaluation and dynamic controlling method. In a case of a cut slope, the variations of UGBs and the impacts of key environmental factors are presented, where more severe construction-triggered geohazards emerged in construction stage than those predicted in design and field investigation stages. As a result, the weight ratios of different influential factors with respect to field investigation, design and construction are obtained.展开更多
This paper presents a five degree of freedom(5-DOF)redundantly actuated parallel mechanism(PM)for the parallel machining head of a machine tool.A 5-DOF single kinematic chain is evolved into a secondary kinematic chai...This paper presents a five degree of freedom(5-DOF)redundantly actuated parallel mechanism(PM)for the parallel machining head of a machine tool.A 5-DOF single kinematic chain is evolved into a secondary kinematic chain based on Lie group theory and a configuration evolution method.The evolutional chain and four 6-DOF kinematic chain SPS(S represents spherical joint and P represents prismatic joint)or UPS(U represents universal joint)can be combined into four classes of 5-DOF redundantly actuated parallel mechanisms.That SPS-(2UPR)R(R represents revolute joint)redundantly actuated parallel mechanism is selected and is applied to the parallel machining head of the machine tool.All formulas of the 4SPS-(2UPR)R mechanism are deduced.The dynamic model of the mechanism is shown to be correct by Matlab and automatic dynamic analysis of mechanical systems(ADAMS)under no-load conditions.The dynamic performance evaluation indexes including energy transmission efficiency and acceleration performance evaluation are analyzed.The results show that the 4SPS-(2UPR)R mechanism can be applied to a parallel machining head and have good dynamic performance.展开更多
In order to accurately predict and control the aging process of dams, new information should be collected continuously to renew the quantitative evaluation of dam safety levels. Owing to the complex structural charact...In order to accurately predict and control the aging process of dams, new information should be collected continuously to renew the quantitative evaluation of dam safety levels. Owing to the complex structural characteristics of dams, it is quite difficult to predict the time-varying factors affecting their safety levels. It is not feasible to employ dynamic reliability indices to evaluate the actual safety levels of dams. Based on the relevant regulations for dam safety classification in China, a dynamic probability description of dam safety levels was developed. Using the Bayesian approach and effective information mining, as well as real-time information, this study achieved more rational evaluation and prediction of dam safety levels. With the Bayesian expression of discrete stochastic variables, the a priori probabilities of the dam safety levels determined by experts were combined wfth the likelihood probability of the real-time check information, and the probability information for the evaluation of dam safety levels was renewed. The probability index was then applied to dam rehabilitation decision-making. This method helps reduce the difficulty and uncertainty of the evaluation of dam safety levels and complies with the current safe decision-making regulations for dams in China. It also enhances the application of current risk analysis methods for dam safety levels.展开更多
Ultra-deepmajor gas fields are typically characterized by high and ultra-high pressure,tightmatrix and developed fractures,so the reserve estimation is of higher uncertainty.In order to accurately estimate the reserve...Ultra-deepmajor gas fields are typically characterized by high and ultra-high pressure,tightmatrix and developed fractures,so the reserve estimation is of higher uncertainty.In order to accurately estimate the reserves of this type of gas reservoir,this paper analyzed the correlation between the effective rock compressibility and the cumulative effective rock compressibility based on the material balance equation of high and ultra-high pressure gas reservoirs,and accordingly selected the material balance based analysis method suitable for the reserves estimation of high and ultra-high pressure gas reservoirs.Then,the starting calculation conditions of reserve estimation were determined using the non-linear regressionmethod.In addition,a semilogarithmic type curvematchingmethodwas established for the caseswhere the starting conditions could not bemet.Finally,thismethodwas applied to calculate the reserves of three ultra-high pressure gas fields(reservoirs)to verify its reliability.And the following research results were obtained.First,the cumulative effective compressibility of gas reservoir in thematerial balance equation of high and ultra-high pressure gas reservoir is a key parameter influencing its reserves,and it is the function of original formation pressure and current average formation pressure,but its numerical value can be hardly obtained by core experiments.Second,it is recommended to adopt the nonlinear regressionmethod without compressibility to estimate the reserves of high and ultra-high pressure gas reservoirs.Third,the calculation starting point of reserves by the nonlinear regression method(the starting point of dimensionless apparent formation pressure-cumulative gas production curve deviating from the straight line relationship)cannot be theoretically calculated.The calculation starting point for different dimensionless linear coefficients(uD)obtained fromthe statistical results by the graphic method corresponds to the dimensionless apparent pressure depletion degree of 0.06-0.38,and that obtained based on the data statistics of the example gas reservoir falls within this interval.Fourth,when the starting conditions are not satisfied,the semi-logarithmic type curve matching method can be used for reserve estimation.The ratio of the reserves to the apparent geological reservesG/G_(app) is a function of uD.The higher the uD,the lower the G/G_(app).Fifth,for the high and ultra-high pressure gas reservoirs in the production test stage,the test production time shall be extended as long as possible to improve the reliability of reserve estimation.And for those in the middle and late stages of development,it is necessary to prepare the comprehensive treatment measures on the basis of reserves so as to improve the development effects of gas reservoirs continuously.展开更多
The integration of urban agglomeration road networks is an inevitable trend of regional development.It is very important to build a scientific and reasonable evaluation system for the integration of urban agglomeratio...The integration of urban agglomeration road networks is an inevitable trend of regional development.It is very important to build a scientific and reasonable evaluation system for the integration of urban agglomeration road networks.The existing research may not be sufficient to evaluate the road network level reliably if the city unit in the region is not considered enough.It is necessary to evaluate the level of road network integration from a dynamic perspective,in consideration of the economic scale of urban population and the level of road network in developing countries such as China is in the stage of rapid development.Therefore,this paper constructs an analytic hierarchy process(AHP)-catastrophe progression method evaluation model by considering the equilibrium degree and the fitness degree of urban unit road network.This evaluation model combines the integration of road network quantity,shape,and quality to evaluate the level of urban agglomeration road network integration from dynamic and static ways.Taking Beijing—Tianjin—Hebei urban agglomeration and Yangtze River Delta urban agglomeration as examples,this paper uses the road network data of urban agglomerations in 2010,2015,and2020 to make a comparative study.The results show that the growing trend of Yangtze River Delta urban agglomeration is at a high level by 2020,while the trend of Beijing—Tianjin—Hebei urban agglomeration is at a general level.Compared with the previous evaluation models,this evaluation method has a good explanation and can emphasize the consideration of dynamic evaluation.The research results annotate the current situation of road network integration of Beijing—Tianjin—Hebei and Yangtze River Delta urban agglomeration that can satisfy the requirement of urban agglomeration development.And it provides decision-making reference for further optimizing of the road network planning and layout of urban agglomeration.展开更多
With the continuous development of artificial intelligence technology,its application field has gradually expanded.To further apply the deep reinforcement learning technology to the field of dynamic pricing,we build a...With the continuous development of artificial intelligence technology,its application field has gradually expanded.To further apply the deep reinforcement learning technology to the field of dynamic pricing,we build an intelligent dynamic pricing system,introduce the reinforcement learning technology related to dynamic pricing,and introduce existing research on the number of suppliers(single supplier and multiple suppliers),environmental models,and selection algorithms.A two-period dynamic pricing game model is designed to assess the optimal pricing strategy for e-commerce platforms under two market conditions and two consumer participation conditions.The first step is to analyze the pricing strategies of e-commerce platforms in mature markets,analyze the optimal pricing and profits of various enterprises under different strategy combinations,compare different market equilibriums and solve the Nash equilibrium.Then,assuming that all consumers are naive in the market,the pricing strategy of the duopoly e-commerce platform in emerging markets is analyzed.By comparing and analyzing the optimal pricing and total profit of each enterprise under different strategy combinations,the subgame refined Nash equilibrium is solved.Finally,assuming that the market includes all experienced consumers,the pricing strategy of the duopoly e-commerce platform in emerging markets is analyzed.展开更多
基金This research was funded by grants from the Natural Science Foundation in Hubei(2018CFB349)the National Natural Sciences Foundation of China(41672155,61733016)Open Research Fund Program of Key Laboratory of Tectonics and Petroleum Resources Ministry of Education(No.TPR-2018-10).
文摘Gas drainage is carried out based on output from each coal bed throughout commingling production of coalbed methane(CBM).A reasonable drainage process should therefore initially guarantee main coal bed production and then enhance gas output from other beds.Permanent damage can result if this is not the case,especially with regard to fracture development in the main gas-producing coal bed and can greatly reduce single well output.Current theoretical models and measuring devices are inapplicable to commingled CBM drainage,however,and so large errors in predictive models cannot always be avoided.The most effective currently available method involves directly measuring gas output from each coal bed as well as determining the dominant gas-producing unit.A dynamic evaluation technique for gas output from each coal bed during commingling CBM production is therefore proposed in this study.This technique comprises a downhole measurement system combined with a theoretical calculation model.Gas output parameters(i.e.,gas-phase flow rate,temperature,pressure)are measured in this approach via a downhole measurement system;substituting these parameters into a deduced theoretical calculation model then means that gas output from each seam can be calculated to determine the main gas-producing unit.Trends in gas output from a single well or each seam can therefore be predicted.The laboratory and field test results presented here demonstrate that calculation errors in CBM outputs can be controlled within a margin of 15%and therefore conform with field use requirements.
基金Project supported by the Social Science Foundation of Shandong Province,China (Grand no.04BJZ44)the Science and Technology project of Shandong Province,China (Grand no.2004GG3206003)
文摘The article establishes the appraisal index system for entire urban agglomeration and its interior cities individually,concretely including five aspects:driving forces for tourism development,the level of tourism development,tourism impacts,tourism economic connection and tourism contributions of different cities to the whole urban agglomeration.As tourism competitiveness has the characteristics of comprehensiveness,systematicness and dynamicness,the article attempts to apply the structural prediction means of system dynamics to evaluating tourism competitiveness,aiming to provide some research methods and analysis ideas for tourism competitiveness measurement and trends analysis in urban agglomeration.Taking Shandong Peninsula urban agglomeration as the study area,the article simulates and analyzes the tourism competitiveness trend of the whole region and its interior cities from 2005 to 2020,and the result reflects that integrated development and regional combination of tourism are important means to upgrade tourism competitiveness in this region.
基金This work was financially supported by the National Key R&D Program of China(No.2020YFB1901900)National Natural Science Foundation of China(No.12275175)+2 种基金Special Fund for Strengthening Industry of Shanghai(No.GYQJ-2018-2-02)Shanghai Rising Star Program(No.21QA1404200)the LingChuang Research Project of the China National Nuclear Corporation.
文摘Micro-mobile heat pipe-cooled nuclear power plants are promising candidates for distributed energy resource power genera-tors and can be flexibly deployed in remote places to meet increasing electric power demands.However,previous steady-state simulations and experiments have deviated significantly from actual micronuclear system operations.Hence,a transient analysis is required for performance optimization and safety assessment.In this study,a hardware-in-the-loop(HIL)approach was used to investigate the dynamic behavior of scaled-down heat pipe-cooled systems.The real-time features of the HIL architecture were interpreted and validated,and an optimal time step of 500 ms was selected for the thermal transient.The power transient was modeled using point kinetic equations,and a scaled-down thermal prototype was set up to avoid mod-eling unpredictable heat transfer behaviors and feeding temperature samples into the main program running on a desktop PC.A series of dynamic test results showed significant power and temperature oscillations during the transient process,owing to the inconsistency of the rapid nuclear reaction rate and large thermal inertia.The proposed HIL approach is stable and effective for further studying of the dynamic characteristics and control optimization of solid-state small nuclear-powered systems at an early prototyping stage.
基金the National Natural Science Founda-tion of China(No.71803110)the“Chen Guang”Project in Shanghai Municipal Education Commis-sion and Shanghai Education Development Foundation(No.19CG41)。
文摘The current method of evaluating passenger satisfaction primarily adopts the traditional static evaluation mode,which can hardly satisfy the dynamic regulatory requirements of highway passenger transport service quality set by industry management departments.In this paper,we summarize the characteristics of real-time dynamic evaluation under the requirements of hierarchical and classified evaluation and analyze the entire process of the one-time travel service of highway passenger transport.We focus on station waiting and in-vehicle services,extract the elements most concerned by passengers as evaluation indexes,and construct a three-level index system.Subsequently,a multi-indicator comprehensive evaluation method based on the analytic hierarchy process and fuzzy comprehensive evaluation is selected to construct a comprehensive evaluation model.By combining with the development level of electronic ticket purchasing and the requirements of satisfaction evaluation,we propose three data collection methods and compare and analyze their strengths and weaknesses.Finally,based on actual survey data,the effectiveness of the model is verified.The verification results show that the real-time dynamic evaluation index system based on the Internet can better satisfy evaluation requirements.
基金supported by the Science and Technology Service Network Plan of the Chinese Academy of Sciences(KFJ-EW-STS-005-02)the International Science&Technology Cooperation Program of China(2013DFG70990)National Natural Science Foundation of China(91225301)
文摘Groundwater resource is vital to the sustainable development of socio-economics in arid and semi-arid regions of Northwest China. An estimation of the groundwater resources variation in Zhangye Basin was made during 1985-2013 based on long-term groundwater observation data and geostatistical method. The results show that from 1985 to 2013, groundwater storage exhibited tremendous dissimilarity on temporal and spatial scale for the whole Zhangye Basin, especially before and after implementation of the water diversion policy. Trend of groundwater storage varied from quick to slow decline or increase. The accumulative groundwater storage decreased nearly 47.52~ 108 m3, and annual average depletion rate reached 1.64x 108 m3/a. Among which, the accumulative groundwater storage of the river and well water mixed irrigation district decreased by 37.48x 108 m3, accounting for about 78.87% of the total groundwater depletion of the Zhangye Basin. Accumulative depletion of groundwater storage varied in respective irrigation districts. Though groundwater resources depletion rate slowed down from 2005, the overall storage in the whole basin and re- spective districts during 1985-2013 was still in a severe deficit such that, the groundwater resource was in a rather negative balance, which could threaten the local aquifer. This is the joint effect of climate change and human activities, however human activities, such as water diversion policy and groundwater exploitation, became increasingly intense. Our research results could provide a reasonable estimation for the groundwater balance in Zhangye Basin, providing a scientific basis for water resources unified planning and, this method can provide a relatively reliable way of estimation for large scale groundwater resources.
基金Sponsored by National Natural Science Foundation of China(NSFC,70071016)
文摘This paper presents dynamic evaluation of enterprise's strategy which is suitable for dealing with the complex and dynamic problems of strategic evaluation. Rough Set Theory is a powerful mathematical tool to handle vagueness and uncertainty of dynamic evaluation. By the application of Rough Set Theory, this paper computes the significance and weights of each evaluation criterion and helps to lay evaluation emphasis on the main and effective criteria. From the reduced decision table,evaluators can get decision rules Which direct them to give judgment or suggestion of strategy. The whole evaluation process is decided by data, so the results are certain and reasonable.
基金"973"National Key Basic Research & Development Program "Research of the Basic Scientific Issues in the Traffic Congestion Bottlenecks of Big Cities"( No. 2006CB705500)Beijing Science & Technology Program "Research of the New Data Collection Technologies for Transportation Management " (No.D101100049710004)Beijing Science & Technology Program "Research of the Demonstration Platform for the In-tegrated Dynamic Operation Analysis of City Road Networks"(No. D07050600440704)
文摘This paper presents an analysis of the random fluctuations, deferred conduction effect and periodicity of road traffic based on the basic features of road networks. It also discusses the limitations of road network evaluation theories based on road "V/C". In addition, it proposes a set of theoretical and technical methods for the real-time evaluation of traffic flows for entire road networks, and for solving key technical issues, such as real-time data collection and processing in areas with no blind zones, the spatial-temporal dynamic analysis of road network traffic, and the calibration of key performance index thresholds. It also provides new technical tools for the strategic transportation planning and real-time diagnosis of road traffic. The new tools and methodology presented in this paper are validated using a case study in Beijing.
文摘Because the static evaluation is unable to reflect the dynamic features of economic benefits and the contribution of sustainable development of low-carbon new energy to economic benefits is huge,this article puts forward the dynamic evaluation model of economic benefits under the development of low-carbon new energy.Total energy,energy consumption structure,industrial structure,GDP,total population and energy supply structure were taken as independent variables,and the carbon intensity was taken as the dependent variable.Through t-test and decision coefficient,total energy,energy consumption structure,GDP and total population were determined as the main factors of influencing low-carbon economy.Based on these four main factors,the dynamic evaluation index system of economic benefits was constructed.Experimental results show that the proposed model can comprehensively reflect the economic benefit level and the contribution of low-carbon new energy.Therefore,this method has high evaluation accuracy,which can provide scientific reference for the economic benefit management of relevant management departments.
文摘Oral English is an important part in higher vocational English teaching. The 2021 edition of "English Curriculum Standard for Higher Vocational Education" puts forward new requirements for higher vocational students oral English ability. The document proposes that "students can use English language knowledge and skills to accurately understand and express information, views and feelings, and communicate effectively orally and in writing." Under such requirements, the traditional final examination evaluation method cannot meet the challenges of the new era. The new evaluation method is intervention dynamic evaluation, which pays attention to the communication between teachers and students and interactive feedback, and continuously adjusts the dynamic form of teaching methods through feedback. Through the intervention dynamic evaluation experiment of oral courses, the author observes whether the new evaluation method can reduce students learning anxiety and improve learning efficiency.
文摘Based on the value theory of mineral resource, a dynamic evaluation model of mineral resource property is erected, which not only takes the factors of extractions into consideration but also those of explorations. The solution process of the model is described and the differential solution is presented. Then the paper comes to the conclusion that the differential solution is also the optimal depletion path of the resource.
基金supported by the Industrial Technology Development Program(B1120131046)。
文摘Configuration evaluation is a key technology to be considered in the design of multiple aircrafts formation(MAF)configurations with high dynamic properties in engineering applications.This paper deduces the relationship between relative velocity,dynamic safety distance and dynamic adjacent distance of formation members,then divides the formation states into collision-state and matching-state.Meanwhile,probability models are constructed based on the binary normal distribution of relative distance and relative velocity.Moreover,configuration evaluation strategies are studied by quantitatively analyzing the denseness and the basic capabilities according to the MAF collision-state probability and the MAF matching-state probability,respectively.The scale of MAF is grouped into 5 levels,and previous lattice-type structures are extended into four degrees by taking the relative velocities into account to instruct the configuration design under complex task conditions.Finally,hardware-in-loop(HIL)simulation and outfield flight test results are presented to verify the feasibility of these evaluation strategies.
基金supported by Gansu Provincial Higher Education Teachers’Innovation Fund under Grant 2025A-124Key Research Project of Gansu University of Political Science and Law under Grant No.GZF2022XZD08Soft Science Special Project of Gansu Basic Research Plan under Grant No.22JR11RA106.
文摘In the complex environment of Wireless Sensor Networks(WSNs),various malicious attacks have emerged,among which internal attacks pose particularly severe security risks.These attacks seriously threaten network stability,data transmission reliability,and overall performance.To effectively address this issue and significantly improve intrusion detection speed,accuracy,and resistance to malicious attacks,this research designs a Three-level Intrusion Detection Model based on Dynamic Trust Evaluation(TIDM-DTE).This study conducts a detailed analysis of how different attack types impact node trust and establishes node models for data trust,communication trust,and energy consumption trust by focusing on characteristics such as continuous packet loss and energy consumption changes.By dynamically predicting node trust values using the grey Markov model,the model accurately and sensitively reflects changes in node trust levels during attacks.Additionally,DBSCAN(Density-Based Spatial Clustering of Applications with Noise)data noise monitoring technology is employed to quickly identify attacked nodes,while a trust recovery mechanism restores the trust of temporarily faulty nodes to reduce False Alarm Rate.Simulation results demonstrate that TIDM-DTE achieves high detection rates,fast detection speed,and low False Alarm Rate when identifying various network attacks,including selective forwarding attacks,Sybil attacks,switch attacks,and black hole attacks.TIDM-DTE significantly enhances network security,ensures secure and reliable data transmission,moderately improves network energy efficiency,reduces unnecessary energy consumption,and provides strong support for the stable operation of WSNs.Meanwhile,the research findings offer new ideas and methods for WSN security protection,possessing important theoretical significance and practical application value.
基金Supported by the National Science Foundation of China (71872047)Innovation Strategy Research Plan of Fujian Province (2021R0077)。
文摘The economy of China has turned to the stage of high-quality development. In this sense,the connotation of regional innovation capacity should reflect more aspects, such as better economic effectiveness, people-centered philosophy of development and better living conditions. This study aims at establishing the evaluation index system of regional innovation capacity under high-quality perspective.Then the dynamic evaluation method based on gray correlation degree and TOPSIS is improved. And the improved method is applied to evaluate the regional innovation capacity under high-quality development perspective. The results show that: 1) The regional innovation capacity of Jiangsu, Zhejiang,Shanghai and Guangdong under high-quality development perspective is better than other regions,while the regional innovation capacity of Beijing-Tianjin-Hebei is imbalanced. Regional innovation capability of Fujian, Shandong, and Hainan from a high-quality perspective is at the middle and lower levels. 2) From the perspective of development trends, the gap of regional innovation capacity between Beijing, Jiangsu, Zhejiang, Shanghai, Guangdong and Fujian, Hebei, Shandong is gradually narrowing.3) An in-depth analysis of the regional innovation capability of the eastern provinces and cities from the perspective of high-quality development through different dimensions shows that Beijing, Guangdong, Jiangsu perform well in all dimensions, while Fujian and Hainan need to pay more attention to innovation input and the creation of a better innovation environment to enhance innovation output and promote innovation effectiveness. At last, based on above analysis, relevant policy recommendations are proposed.
文摘Currently, traditional development issues, such as economic stagnation, as well as new challenges like environmental degradation and globalization, need attention. Sustainable development, including economic, environmental, and social elements, is a main goal of decision-makers. The key to sustainable decision-making is to evaluate and forecast the status quo of sustainable development. Policy makers need a tool based on scientific information to forecast the effects of future actions on sustainability and make policies for sustainable development. This paper analyzes the relation of the economy, environment and social welfare by the grey dynamic model. The proposed method uses time series and basic indicators of ecological system, including economic, environmental and social sub-systems. It is applied to Heilongjiang Province and Jiangsu Province. The results have proved different status quo of sustainable development in these two regions, and suggestions are proposed, such as optimization of industrial structure and eco-industrial development. The conclusion is that there is no unique sustainable path, and accordingly, policy makers should choose different criteria and strategies to make efficient sustainable decisions for each region.
基金support by the National Natural Science Foundation of China (No. 41372324)support from the Chinese Special Funds for Major State Basic Research Project under Grant No. 2010CB732001
文摘The new Austrian tunneling method （NATM） is widely applied in design and construction of underground engineering projects. When the type and distribution of unfavorable geological bodies （UGBs） associated with their influences on geoengineering are complicated or unfortunately are overlooked, we should pay more attentions to internal features of rocks grades IV and V （even in local but mostly controlling zones）. With increasing attentions to the characteristics, mechanism and influences of engineering construction-triggered geohazards, it is crucial to fully understand the disturbance of these geohazards on project construction. A reasonable determination method in construction procedure, i.e. the shape of working face, the type of engineering support and the choice of feasible procedure, should be considered in order to mitigate the construction-triggered geohazards. Due to their high sensitivity to groundwater and in-situ stress, various UGBs exhibit hysteretic nature and failure modes. To give a complete understanding on the internal causes, the emphasis on advanced comprehensive geological forecasting and overall reinforcement treatment is therefore of more practical significance. Compre- hensive evaluation of influential factors, identification of UGB, and measures of discontinuity dynamic controlling comprises the geoengineering condition evaluation and dynamic controlling method. In a case of a cut slope, the variations of UGBs and the impacts of key environmental factors are presented, where more severe construction-triggered geohazards emerged in construction stage than those predicted in design and field investigation stages. As a result, the weight ratios of different influential factors with respect to field investigation, design and construction are obtained.
基金the Fundamental Research Funds for the Central Universities(No.2018 JBZ007).
文摘This paper presents a five degree of freedom(5-DOF)redundantly actuated parallel mechanism(PM)for the parallel machining head of a machine tool.A 5-DOF single kinematic chain is evolved into a secondary kinematic chain based on Lie group theory and a configuration evolution method.The evolutional chain and four 6-DOF kinematic chain SPS(S represents spherical joint and P represents prismatic joint)or UPS(U represents universal joint)can be combined into four classes of 5-DOF redundantly actuated parallel mechanisms.That SPS-(2UPR)R(R represents revolute joint)redundantly actuated parallel mechanism is selected and is applied to the parallel machining head of the machine tool.All formulas of the 4SPS-(2UPR)R mechanism are deduced.The dynamic model of the mechanism is shown to be correct by Matlab and automatic dynamic analysis of mechanical systems(ADAMS)under no-load conditions.The dynamic performance evaluation indexes including energy transmission efficiency and acceleration performance evaluation are analyzed.The results show that the 4SPS-(2UPR)R mechanism can be applied to a parallel machining head and have good dynamic performance.
基金supported by the National Science and Technology Support Program of China (Program for the Eleventh Five-Year Plan, Grant No. 2006BAC14B03 and 2006BAC05B03)the National Natural Science Foundation of China (Grant No. 50679043)
文摘In order to accurately predict and control the aging process of dams, new information should be collected continuously to renew the quantitative evaluation of dam safety levels. Owing to the complex structural characteristics of dams, it is quite difficult to predict the time-varying factors affecting their safety levels. It is not feasible to employ dynamic reliability indices to evaluate the actual safety levels of dams. Based on the relevant regulations for dam safety classification in China, a dynamic probability description of dam safety levels was developed. Using the Bayesian approach and effective information mining, as well as real-time information, this study achieved more rational evaluation and prediction of dam safety levels. With the Bayesian expression of discrete stochastic variables, the a priori probabilities of the dam safety levels determined by experts were combined wfth the likelihood probability of the real-time check information, and the probability information for the evaluation of dam safety levels was renewed. The probability index was then applied to dam rehabilitation decision-making. This method helps reduce the difficulty and uncertainty of the evaluation of dam safety levels and complies with the current safe decision-making regulations for dams in China. It also enhances the application of current risk analysis methods for dam safety levels.
基金supported by the Major Science and Technology Project of PetroChina Company Limited“Research and Application of Key Technologies for Development of Deep and Ultra-deep Gas Fields in Kuqa Depression”(No.2018E-1803).
文摘Ultra-deepmajor gas fields are typically characterized by high and ultra-high pressure,tightmatrix and developed fractures,so the reserve estimation is of higher uncertainty.In order to accurately estimate the reserves of this type of gas reservoir,this paper analyzed the correlation between the effective rock compressibility and the cumulative effective rock compressibility based on the material balance equation of high and ultra-high pressure gas reservoirs,and accordingly selected the material balance based analysis method suitable for the reserves estimation of high and ultra-high pressure gas reservoirs.Then,the starting calculation conditions of reserve estimation were determined using the non-linear regressionmethod.In addition,a semilogarithmic type curvematchingmethodwas established for the caseswhere the starting conditions could not bemet.Finally,thismethodwas applied to calculate the reserves of three ultra-high pressure gas fields(reservoirs)to verify its reliability.And the following research results were obtained.First,the cumulative effective compressibility of gas reservoir in thematerial balance equation of high and ultra-high pressure gas reservoir is a key parameter influencing its reserves,and it is the function of original formation pressure and current average formation pressure,but its numerical value can be hardly obtained by core experiments.Second,it is recommended to adopt the nonlinear regressionmethod without compressibility to estimate the reserves of high and ultra-high pressure gas reservoirs.Third,the calculation starting point of reserves by the nonlinear regression method(the starting point of dimensionless apparent formation pressure-cumulative gas production curve deviating from the straight line relationship)cannot be theoretically calculated.The calculation starting point for different dimensionless linear coefficients(uD)obtained fromthe statistical results by the graphic method corresponds to the dimensionless apparent pressure depletion degree of 0.06-0.38,and that obtained based on the data statistics of the example gas reservoir falls within this interval.Fourth,when the starting conditions are not satisfied,the semi-logarithmic type curve matching method can be used for reserve estimation.The ratio of the reserves to the apparent geological reservesG/G_(app) is a function of uD.The higher the uD,the lower the G/G_(app).Fifth,for the high and ultra-high pressure gas reservoirs in the production test stage,the test production time shall be extended as long as possible to improve the reliability of reserve estimation.And for those in the middle and late stages of development,it is necessary to prepare the comprehensive treatment measures on the basis of reserves so as to improve the development effects of gas reservoirs continuously.
基金supported by the Hebei Key Research and Development Program(22370801D)the Hebei Province Yanzhao Golden Terrace Talent Program Key Talent Project(Education Platform)(HJZD202514)the National Natural Science Foundation of China,China(52172304,52372302)。
文摘The integration of urban agglomeration road networks is an inevitable trend of regional development.It is very important to build a scientific and reasonable evaluation system for the integration of urban agglomeration road networks.The existing research may not be sufficient to evaluate the road network level reliably if the city unit in the region is not considered enough.It is necessary to evaluate the level of road network integration from a dynamic perspective,in consideration of the economic scale of urban population and the level of road network in developing countries such as China is in the stage of rapid development.Therefore,this paper constructs an analytic hierarchy process(AHP)-catastrophe progression method evaluation model by considering the equilibrium degree and the fitness degree of urban unit road network.This evaluation model combines the integration of road network quantity,shape,and quality to evaluate the level of urban agglomeration road network integration from dynamic and static ways.Taking Beijing—Tianjin—Hebei urban agglomeration and Yangtze River Delta urban agglomeration as examples,this paper uses the road network data of urban agglomerations in 2010,2015,and2020 to make a comparative study.The results show that the growing trend of Yangtze River Delta urban agglomeration is at a high level by 2020,while the trend of Beijing—Tianjin—Hebei urban agglomeration is at a general level.Compared with the previous evaluation models,this evaluation method has a good explanation and can emphasize the consideration of dynamic evaluation.The research results annotate the current situation of road network integration of Beijing—Tianjin—Hebei and Yangtze River Delta urban agglomeration that can satisfy the requirement of urban agglomeration development.And it provides decision-making reference for further optimizing of the road network planning and layout of urban agglomeration.
基金His work is supported by Scientific research planning project of Jilin Provincial Department of education in 2020:Analysis of the impact of industrial upgrading on employment of college students in Jilin Province(No.JJKH20200505JY).
文摘With the continuous development of artificial intelligence technology,its application field has gradually expanded.To further apply the deep reinforcement learning technology to the field of dynamic pricing,we build an intelligent dynamic pricing system,introduce the reinforcement learning technology related to dynamic pricing,and introduce existing research on the number of suppliers(single supplier and multiple suppliers),environmental models,and selection algorithms.A two-period dynamic pricing game model is designed to assess the optimal pricing strategy for e-commerce platforms under two market conditions and two consumer participation conditions.The first step is to analyze the pricing strategies of e-commerce platforms in mature markets,analyze the optimal pricing and profits of various enterprises under different strategy combinations,compare different market equilibriums and solve the Nash equilibrium.Then,assuming that all consumers are naive in the market,the pricing strategy of the duopoly e-commerce platform in emerging markets is analyzed.By comparing and analyzing the optimal pricing and total profit of each enterprise under different strategy combinations,the subgame refined Nash equilibrium is solved.Finally,assuming that the market includes all experienced consumers,the pricing strategy of the duopoly e-commerce platform in emerging markets is analyzed.
