Peer feedback is an indispensable part in process writing. However, in college English class, students pay less attention to peer feedback than teachers' feedback. What's more, without teachers' guidance, ...Peer feedback is an indispensable part in process writing. However, in college English class, students pay less attention to peer feedback than teachers' feedback. What's more, without teachers' guidance, most of students don't know how to give feedbacks and what feedbacks should be given. Therefore, some strategies should be used to help students to make more effective feedbacks and stimulate students' interest to actively learn from their peers.展开更多
Production planning models generated by common modeling systems do not involve constraints for process operations, and a solution optimized by these models is called a quasi-optimal plan. The quasi-optimal plan cannot...Production planning models generated by common modeling systems do not involve constraints for process operations, and a solution optimized by these models is called a quasi-optimal plan. The quasi-optimal plan cannot be executed in practice some time for no corresponding operating conditions. In order to determine a practi- cally feasible optimal plan and corresponding operating conditions of fluidized catalytic cracking unit (FCCU), a novel close-loop integrated strategy, including determination of a quasi-optimal plan, search of operating conditions of FCCU and revision of the production planning model, was proposed in this article. In the strategy, a generalized genetic algorithm (GA) coupled with a sequential process simulator of FCCU was applied to search operating conditions implementing the quasi-optimal plan of FCCU and output the optimal individual in the GA search as a final genetic individual. When no corresponding operating conditions were found, the final genetic individual based correction (FGIC) method was presented to revise the production planning model, and then a new quasi-optimal production plan was determined. The above steps were repeated until a practically feasible optimal plan and corresponding operating conditions of FCCU were obtained. The close-loop integrated strategy was validated by two cases, and it was indicated that the strategy was efficient in determining a practically executed optimal plan and corresponding operating conditions of FCCU.展开更多
Aiming at the limitations of the existing knowledge representations in intelligent detection, a new method of Extension-based Knowledge Representation (EKR) was proposed. The definitions, grammar rules, and storage st...Aiming at the limitations of the existing knowledge representations in intelligent detection, a new method of Extension-based Knowledge Representation (EKR) was proposed. The definitions, grammar rules, and storage structure of EKR were presented. An Extension Solving Model (ESM) based on EKR was discussed in detail, including creation of the extension constraint graph, extended inference, calculation of relevant functions and generation of extension set. A knowledge base system based on EKR and ESM was developed, which was applied in extension repository system intelligent design of detection in photosynthesis process of D.huoshanense. More reasonable results were obtained than traditional rule-based system. EKR was feasible in intelligent design to solve the problem of intelligent detection knowledge representations.展开更多
Advanced Process Control (APC) is necessary for oil refining and chemical process in China, but some problems have emerged in the application of APC techniques in this field. This paper discusses the conditions of A...Advanced Process Control (APC) is necessary for oil refining and chemical process in China, but some problems have emerged in the application of APC techniques in this field. This paper discusses the conditions of APC application concerning process design, distributed control system (DCS) choice and regular control. It analyzes the problems and strategies in APC application. Some suggestions are proposed for the enterprise to benefit from APC application.展开更多
Securities investment fund is one of the most important institutional investors in the securities market. The quality of the management of the securities investment fund by the fund management company not only directl...Securities investment fund is one of the most important institutional investors in the securities market. The quality of the management of the securities investment fund by the fund management company not only directly affects its survival and development,but also plays a decisive role in the stable operation of securities market and even the macroeconomy. As China is in rapid development of funds,scientific and effective investment strategies will be the only road for the long-term development of wellestablished fund management companies. We attempt to combine the value investment strategies with quantitative investment strategies to build a system of optimized investment strategies with the use of analytic hierarchy process so as to improve business performance of fund management companies and to foster the concept of value investment. Moreover,it possesses certain significance in enriching investment strategies for securities investment fund and promoting the healthy growth of the Chinese securities investment fund.展开更多
The shifting requirements as imposed on operations ma nagement require adjusting and tailoring the organisational structure to meet ma rket demands. However, translating these requirements directly into hierarchical s...The shifting requirements as imposed on operations ma nagement require adjusting and tailoring the organisational structure to meet ma rket demands. However, translating these requirements directly into hierarchical structure will not ensure the integration of processes across organisational un its and guarantee desirable performance. Therefore, management and management li terature wonders: · How should we connect processes to the external environment within a strategi c framework · Which organisational structures do meet performance requirements · Which choices and freedom do we have within organisational structures · How and when do we implement organisational structures That the hierarchical structure does not meet as such the performance requiremen ts nor did it relate to these became already clear during case studies performed in the ’70s. The conclusion was drawn that organisational changes should affect working processes before they proof to be viable. This required the development of new approach through empirical studies and base d on literature. This led to the development of the organelle structure. The org anelle structure should connect to the strategy and the product flow. Thereto, a decision model has been developed for revealing these relations and the practic al implication. During a number of case studies this methodology has been refined and includes t he strategic choice between variants for the organelle structure with their own performance capabilities; we distinguish about 20 variants ranging between the f unctional organisation and the product flow organisation. These ranges of choice s however can be connected to different order entry points, stemming from logist ic concepts. This extends the performance to improved lead-times and improved c ontrol. Strategic choices relate the organelle structure to external performance criteria dictated by product/market-combinations: · lead-time · quality · costs and internal choices for performance criteria: · flexibility · productivity · resource utilisation · innovative performance. Case studies reveal the drastic improvements of the performance of operations an d manufacturing. The paper will discuss a few of these implementations to demons trate the impact. They also show how one derives the hierarchical structure from the choice for the organelle structure. Organelle structures do bridge the link of an industrial company to its environm ent and the internal possibilities, dictated by characteristics of product flow and process execution. The link to the environment results in a strategic framew ork for assessment of alternatives and possibilities. Choices for organelle stru ctures depend strongly on choices on the order entry points of the hardware flow and the specification flow. The evaluation of the characteristics takes place a gainst the strategic framework ensuring competitive advantage as well as a high probability of factual implementation and performance improvement.展开更多
This paper sets to explore management perceptions regarding the impact of operational process factors on strategy implementation in microfinance organisations in Kenya.Small and medium enterprises(SMEs)play a critical...This paper sets to explore management perceptions regarding the impact of operational process factors on strategy implementation in microfinance organisations in Kenya.Small and medium enterprises(SMEs)play a critical role in developing countries as a source of employment creation and a basis for industrialization.However,the sector receives inadequate financial support from commercial banks as it is considered to bear high risks and operational costs associate with lending small loan amounts.Microfinance organisations(MFOs)that serve this sector will need to expand their operations to increase their outreach to SMEs.Formulation and implementation of competitive strategies will enable MFOs to achieve growth and sustainability.Content,context and operational process factors appear to have a significance positive relationship to the level of strategy implementation.This paper is focusing on operational process factors impacting on strategy implementation and is part of a full study on the topic of strategy implementation in MFOs.Comprehensive literature review provided the theoretical framework for the study.Primary data were collected by means of a survey obtaining 300 self-administered questionnaires from managers in 135 MFOs in Kenya.The study revealed that the level of strategy implementation in MFOs in Kenya is moderate to high.This study has revealed that the operational process category of factors is more significant to the level of strategy implementation than content and context factors.Five operational process factors critical to strategy implementation include:operational planning and monitoring,management control systems,people-strategy fit,teamwork,and effective communication.Further,the level of strategy implementation has significance positive influence to MFOs’financial sustainability and outreach.Practical guidelines are provided to assist MFOs in developing countries to improve the level of strategy implementation by focusing on operational process factors.展开更多
Deep shale reservoirs are characterized by elevated breakdown pressures,diminished fracture complexity,and reduced modified volumes compared to medium and shallow reservoirs.Therefore,it is urgent to investigate parti...Deep shale reservoirs are characterized by elevated breakdown pressures,diminished fracture complexity,and reduced modified volumes compared to medium and shallow reservoirs.Therefore,it is urgent to investigate particular injection strategies that can optimize breakdown pressure and fracturing efficiency to address the increasing demands for deep shale reservoir stimulation.In this study,the efficiency of various stimulation strategies,including multi-cluster simultaneous fracturing,modified alternating fracturing,alternating shut-in fracturing,and cyclic alternating fracturing,was evaluated.Subsequently,the sensitivity of factors such as the cycle index,shut-in time,cluster spacing,and horizontal permeability was investigated.Additionally,the flow distribution effect within the wellbore was discussed.The results indicate that relative to multi-cluster simultaneous fracturing,modified alternating fracturing exhibits reduced susceptibility to the stress shadow effect,which results in earlier breakdown,extended hydraulic fracture lengths,and more consistent propagation despite an increase in breakdown pressure.The alternating shut-in fracturing benefits the increase of fracture length,which is closely related to the shut-in time.Furthermore,cyclic alternating fracturing markedly lowers breakdown pressure and contributes to uniform fracture propagation,in which the cycle count plays an important role.Modified alternating fracturing demonstrates insensitivity to variations in cluster spacing,whereas horizontal permeability is a critical factor affecting fracture length.The wellbore effect restrains the accumulation of pressure and flow near the perforation,delaying the initiation of hydraulic fractures.The simulation results can provide valuable numerical insights for optimizing injection strategies for deep shale hydraulic fracturing.展开更多
Process writing has been commonly recognized by scholars as an effective writing strategy and widely applied in the teaching of writing. The stages of process writing have been elaborated in this paper through the int...Process writing has been commonly recognized by scholars as an effective writing strategy and widely applied in the teaching of writing. The stages of process writing have been elaborated in this paper through the introduction of overseas core articles in this field from a scientific perspective combined with a cognition angle. Implications have been put forward to teachers at the end of this paper.展开更多
In foreign language learning, many learners seem to have difficulty in reading accurately and efficiently so as to understand as much of a text as one needs in order to achieve one’s purpose. To help learners become ...In foreign language learning, many learners seem to have difficulty in reading accurately and efficiently so as to understand as much of a text as one needs in order to achieve one’s purpose. To help learners become more effective readers, it is crucial to develop relevant reading strategies in the light of their needs. This essay is intended to exploit how to help learners improve their second or foreign language reading strategies on the basis of a general understanding of the relevant literature. Holding the belief that the strategies chosen for the learners to be developed in the classroom should suit their needs, this essay mainly focuses on developing the learners’ top-down reading strategies such as predicting topics, which seems particularly relevant to the group of learners that I am familiar with. In an attempt to exemplify how to help learners of English develop their relevant reading strategies in English classes, a description of classroom procedures will be offered.展开更多
By using a generalized fitness-dependent Moran process, an evolutionary model for symmetric 2 × 2 games in a well-mixed population with a finite size is investigated. In the model, the individuals' payoff accumu...By using a generalized fitness-dependent Moran process, an evolutionary model for symmetric 2 × 2 games in a well-mixed population with a finite size is investigated. In the model, the individuals' payoff accumulating from games is mapped into fitness using an exponent function. Both selection strength β and mutation rate ε are considered. The process is an ergodic birth-death process. Based on the limit distribution of the process, we give the analysis results for which strategy will be favoured when s is small enough. The results depend on not only the payoff matrix of the game, but also on the population size. Especially, we prove that natural selection favours the strategy which is risk-dominant when the population size is large enough. For arbitrary β and ε values, the 'Hawk-Dove' game and the 'Coordinate' game are used to illustrate our model. We give the evolutionary stable strategy (ESS) of the games and compare the results with those of the replicator dynamics in the infinite population. The results are determined by simulation experiments.展开更多
In this article, a threshold dividend strategy is used for classical risk model. Under this dividend strategy, certain probability of ruin, which occurs in case of constant barrier strategy, is avoided. Using the stro...In this article, a threshold dividend strategy is used for classical risk model. Under this dividend strategy, certain probability of ruin, which occurs in case of constant barrier strategy, is avoided. Using the strong Markov property of the surplus process and the distribution of the deficit in classical risk model, the survival probability for this model is derived, which is more direct than that in Asmussen(2000, P195, Proposition 1.10). The occupation time of non-dividend of this model is also discussed by means of Martingale method.展开更多
Although small cell offloading technology can alleviate the congestion in macrocell, aggressively offloading data traffic from macrocell to small cell can also degrade the performance of small cell due to the heavy lo...Although small cell offloading technology can alleviate the congestion in macrocell, aggressively offloading data traffic from macrocell to small cell can also degrade the performance of small cell due to the heavy load. Because of collision and backoff, the degradation is significant especially in network with contention-based channel access, and finally decreases throughput of the whole network. To find an optimal fraction of traffic to be offloaded in heterogeneous network, we combine Markov chain with the Poisson point process model to analyze contention-based throughput in irregularly deployment networks. Then we derive the close-form solution of the throughput and find that it is a function of the transmit power and density of base stations.Based on this, we propose the load-aware offloading strategies via power control and base station density adjustment. The numerical results verify our analysis and show a great performance gain compared with non-load-aware offloading.展开更多
This paper briefly reviews some significant learning strategies in L2 listening research.By pointing out both the feasibil ities and difficulties in implementing those strategies in Chinese EFL classrooms,it attempts ...This paper briefly reviews some significant learning strategies in L2 listening research.By pointing out both the feasibil ities and difficulties in implementing those strategies in Chinese EFL classrooms,it attempts to raise English language practitio ners'awareness of reforming the listening instruction and of utilizing strategic teaching approaches so as to enhance students'lis tening proficiency.展开更多
Evolutionary game dynamics in finite size populations can be described by a fitness-dependent Wright- Fisher process. We consider symmetric 2×2 games in a well-mixed population. In our model, two parameters to de...Evolutionary game dynamics in finite size populations can be described by a fitness-dependent Wright- Fisher process. We consider symmetric 2×2 games in a well-mixed population. In our model, two parameters to describe the level of player's rationality and noise intensity in environment are introduced. In contrast with the fixation probability method that used in a noiseless case, the introducing of the noise intensity parameter makes the process an ergodic Markov process and based on the limit distribution of the process, we can analysis the evolutionary stable strategy (ESS) of the games. We illustrate the effects of the two parameters on the ESS of games using the Prisoner's dilemma games (PDG) and the snowdrift games (SG). We also compare the ESS of our model with that of the replicator dynamics in infinite size populations. The results are determined by simulation experiments.展开更多
Testing is the premise and foundation of realizing equipment health management (EHM). To address the problem that the static periodic test strategy may cause deficient test or excessive test, a dynamic sequential te...Testing is the premise and foundation of realizing equipment health management (EHM). To address the problem that the static periodic test strategy may cause deficient test or excessive test, a dynamic sequential test strategy (DSTS) for EHM is presented. Considering the situation that equipment health state is not completely observable in reality, a DSTS optimization method based on partially observable semi-Markov decision pro- cess (POSMDP) is proposed. Firstly, an equipment health state degradation model is constructed by Markov process, and the control limit maintenance policy is also introduced. Secondly, POSMDP is formulated in great detail. And then, POSMDP is converted to completely observable belief semi-Markov decision process (BSMDP) through belief state. The optimal equation and the corresponding optimal DSTS, which minimize the long-run ex- pected average cost per unit time, are obtained with BSMDP. The results of application in complex equipment show that the proposed DSTS is feasible and effective.展开更多
The quantitative evaluation of multi-process collaborative operation is of great significance for the improvement of production planning and scheduling in steelmaking–continuous casting sections(SCCSs). However, this...The quantitative evaluation of multi-process collaborative operation is of great significance for the improvement of production planning and scheduling in steelmaking–continuous casting sections(SCCSs). However, this evaluation is difficult since it relies on an in-depth understanding of the operating mechanism of SCCSs, and few existing methods can be used to conduct the evaluation, due to the lack of full-scale consideration of the multiple factors related to the production operation. In this study, three quantitative models were developed, and the multiprocess collaborative operation level was evaluated through the laminar-flow operation degree, the process matching degree, and the scheduling strategy availability degree. Based on the evaluation models for the laminar-flow operation and process matching levels, this study investigated the production status of two steelmaking plants, plants A and B, based on actual production data. The average laminar-flow operation(process matching) degrees of SCCSs were obtained as 0.638(0.610) and 1.000(0.759) for plants A and B, respectively, for the period of April to July 2019. Then, a scheduling strategy based on the optimization of the furnace-caster coordinating mode was suggested for plant A. Simulation experiments showed higher availability than the greedy-based and manual strategies. After the proposed scheduling strategy was applied,the average process matching degree of the SCCS of plant A increased by 4.6% for the period of September to November 2019. The multi-process collaborative operation level was improved with fewer adjustments and interruptions in casting.展开更多
Sulfate radical-advanced oxidation processes(SR-AOPs)are promising technologies for organic pollutants elimination.Heterogeneous metal-based catalysis has been widely studied and applied to activate peroxymonosulfate(...Sulfate radical-advanced oxidation processes(SR-AOPs)are promising technologies for organic pollutants elimination.Heterogeneous metal-based catalysis has been widely studied and applied to activate peroxymonosulfate(PMS)for producing sulfate radicals.Developing highly efficient catalysts is crucial for future extensive use.Importantly,the catalytic activity is mainly determined by mass and electron transfer.This paper aims to overview the recent enhancement strategies for developing heterogeneous metalbased catalysts as effective PMS activators.The main strategies,including surface engineering,structural engineering,electronic modulation,external energy assistance,and membrane filtration enhancement,are summarized.The potential mechanisms for improving catalytic activity are also introduced.Finally,the challenges and future research prospects of heterogenous metal-based catalysis in SR-AOPs are proposed.This work is hoped to guide the rational design of highly efficient heterogenous catalysts in SR-AOPs.展开更多
The quality standards for Fructus Comi have been established based on the effects of the manufacturing processes.Three critical process parameters(CPPs)of extraction,filtration,and concentration to prepare Fructus Com...The quality standards for Fructus Comi have been established based on the effects of the manufacturing processes.Three critical process parameters(CPPs)of extraction,filtration,and concentration to prepare Fructus Comi concentrate were identified by Plackett-Burman design with a single batch of Fructus Corni,which were heating medium temperature,extraction time,and water addition.Morroniside yield,loganin yield,and dry matter yield were process critical quality attributes(CQAs).CPPs arranged with a Box-Behnken design were applied to treat different batches of Fructus Comi After constructing a model that included CPPs,material propertie s,and process CQAs,loganin content was found to be the critical material attribute(CMA).The design space was calculated with a probability method.According to the limits of process CQAs,the minimum content of loganin in Fructus Corni was calculated with an error propagation method,which was 6.92 mg·g^(-1).When the content of loganin in Fructus Corni reaches up to 6.92 mg·g^(-1),the material is considered high-quality and is most suitable for the process.High-quality material can be used for production of Fructus Comi concentrate.This method can also be used to set material quality standards for other Chinese medicines.展开更多
文摘Peer feedback is an indispensable part in process writing. However, in college English class, students pay less attention to peer feedback than teachers' feedback. What's more, without teachers' guidance, most of students don't know how to give feedbacks and what feedbacks should be given. Therefore, some strategies should be used to help students to make more effective feedbacks and stimulate students' interest to actively learn from their peers.
文摘Production planning models generated by common modeling systems do not involve constraints for process operations, and a solution optimized by these models is called a quasi-optimal plan. The quasi-optimal plan cannot be executed in practice some time for no corresponding operating conditions. In order to determine a practi- cally feasible optimal plan and corresponding operating conditions of fluidized catalytic cracking unit (FCCU), a novel close-loop integrated strategy, including determination of a quasi-optimal plan, search of operating conditions of FCCU and revision of the production planning model, was proposed in this article. In the strategy, a generalized genetic algorithm (GA) coupled with a sequential process simulator of FCCU was applied to search operating conditions implementing the quasi-optimal plan of FCCU and output the optimal individual in the GA search as a final genetic individual. When no corresponding operating conditions were found, the final genetic individual based correction (FGIC) method was presented to revise the production planning model, and then a new quasi-optimal production plan was determined. The above steps were repeated until a practically feasible optimal plan and corresponding operating conditions of FCCU were obtained. The close-loop integrated strategy was validated by two cases, and it was indicated that the strategy was efficient in determining a practically executed optimal plan and corresponding operating conditions of FCCU.
文摘Aiming at the limitations of the existing knowledge representations in intelligent detection, a new method of Extension-based Knowledge Representation (EKR) was proposed. The definitions, grammar rules, and storage structure of EKR were presented. An Extension Solving Model (ESM) based on EKR was discussed in detail, including creation of the extension constraint graph, extended inference, calculation of relevant functions and generation of extension set. A knowledge base system based on EKR and ESM was developed, which was applied in extension repository system intelligent design of detection in photosynthesis process of D.huoshanense. More reasonable results were obtained than traditional rule-based system. EKR was feasible in intelligent design to solve the problem of intelligent detection knowledge representations.
文摘Advanced Process Control (APC) is necessary for oil refining and chemical process in China, but some problems have emerged in the application of APC techniques in this field. This paper discusses the conditions of APC application concerning process design, distributed control system (DCS) choice and regular control. It analyzes the problems and strategies in APC application. Some suggestions are proposed for the enterprise to benefit from APC application.
文摘Securities investment fund is one of the most important institutional investors in the securities market. The quality of the management of the securities investment fund by the fund management company not only directly affects its survival and development,but also plays a decisive role in the stable operation of securities market and even the macroeconomy. As China is in rapid development of funds,scientific and effective investment strategies will be the only road for the long-term development of wellestablished fund management companies. We attempt to combine the value investment strategies with quantitative investment strategies to build a system of optimized investment strategies with the use of analytic hierarchy process so as to improve business performance of fund management companies and to foster the concept of value investment. Moreover,it possesses certain significance in enriching investment strategies for securities investment fund and promoting the healthy growth of the Chinese securities investment fund.
文摘The shifting requirements as imposed on operations ma nagement require adjusting and tailoring the organisational structure to meet ma rket demands. However, translating these requirements directly into hierarchical structure will not ensure the integration of processes across organisational un its and guarantee desirable performance. Therefore, management and management li terature wonders: · How should we connect processes to the external environment within a strategi c framework · Which organisational structures do meet performance requirements · Which choices and freedom do we have within organisational structures · How and when do we implement organisational structures That the hierarchical structure does not meet as such the performance requiremen ts nor did it relate to these became already clear during case studies performed in the ’70s. The conclusion was drawn that organisational changes should affect working processes before they proof to be viable. This required the development of new approach through empirical studies and base d on literature. This led to the development of the organelle structure. The org anelle structure should connect to the strategy and the product flow. Thereto, a decision model has been developed for revealing these relations and the practic al implication. During a number of case studies this methodology has been refined and includes t he strategic choice between variants for the organelle structure with their own performance capabilities; we distinguish about 20 variants ranging between the f unctional organisation and the product flow organisation. These ranges of choice s however can be connected to different order entry points, stemming from logist ic concepts. This extends the performance to improved lead-times and improved c ontrol. Strategic choices relate the organelle structure to external performance criteria dictated by product/market-combinations: · lead-time · quality · costs and internal choices for performance criteria: · flexibility · productivity · resource utilisation · innovative performance. Case studies reveal the drastic improvements of the performance of operations an d manufacturing. The paper will discuss a few of these implementations to demons trate the impact. They also show how one derives the hierarchical structure from the choice for the organelle structure. Organelle structures do bridge the link of an industrial company to its environm ent and the internal possibilities, dictated by characteristics of product flow and process execution. The link to the environment results in a strategic framew ork for assessment of alternatives and possibilities. Choices for organelle stru ctures depend strongly on choices on the order entry points of the hardware flow and the specification flow. The evaluation of the characteristics takes place a gainst the strategic framework ensuring competitive advantage as well as a high probability of factual implementation and performance improvement.
文摘This paper sets to explore management perceptions regarding the impact of operational process factors on strategy implementation in microfinance organisations in Kenya.Small and medium enterprises(SMEs)play a critical role in developing countries as a source of employment creation and a basis for industrialization.However,the sector receives inadequate financial support from commercial banks as it is considered to bear high risks and operational costs associate with lending small loan amounts.Microfinance organisations(MFOs)that serve this sector will need to expand their operations to increase their outreach to SMEs.Formulation and implementation of competitive strategies will enable MFOs to achieve growth and sustainability.Content,context and operational process factors appear to have a significance positive relationship to the level of strategy implementation.This paper is focusing on operational process factors impacting on strategy implementation and is part of a full study on the topic of strategy implementation in MFOs.Comprehensive literature review provided the theoretical framework for the study.Primary data were collected by means of a survey obtaining 300 self-administered questionnaires from managers in 135 MFOs in Kenya.The study revealed that the level of strategy implementation in MFOs in Kenya is moderate to high.This study has revealed that the operational process category of factors is more significant to the level of strategy implementation than content and context factors.Five operational process factors critical to strategy implementation include:operational planning and monitoring,management control systems,people-strategy fit,teamwork,and effective communication.Further,the level of strategy implementation has significance positive influence to MFOs’financial sustainability and outreach.Practical guidelines are provided to assist MFOs in developing countries to improve the level of strategy implementation by focusing on operational process factors.
基金supported by the National Natural Science Foundation of China(NSFC)(Grant Nos.42377156,42077251 and 42202305).
文摘Deep shale reservoirs are characterized by elevated breakdown pressures,diminished fracture complexity,and reduced modified volumes compared to medium and shallow reservoirs.Therefore,it is urgent to investigate particular injection strategies that can optimize breakdown pressure and fracturing efficiency to address the increasing demands for deep shale reservoir stimulation.In this study,the efficiency of various stimulation strategies,including multi-cluster simultaneous fracturing,modified alternating fracturing,alternating shut-in fracturing,and cyclic alternating fracturing,was evaluated.Subsequently,the sensitivity of factors such as the cycle index,shut-in time,cluster spacing,and horizontal permeability was investigated.Additionally,the flow distribution effect within the wellbore was discussed.The results indicate that relative to multi-cluster simultaneous fracturing,modified alternating fracturing exhibits reduced susceptibility to the stress shadow effect,which results in earlier breakdown,extended hydraulic fracture lengths,and more consistent propagation despite an increase in breakdown pressure.The alternating shut-in fracturing benefits the increase of fracture length,which is closely related to the shut-in time.Furthermore,cyclic alternating fracturing markedly lowers breakdown pressure and contributes to uniform fracture propagation,in which the cycle count plays an important role.Modified alternating fracturing demonstrates insensitivity to variations in cluster spacing,whereas horizontal permeability is a critical factor affecting fracture length.The wellbore effect restrains the accumulation of pressure and flow near the perforation,delaying the initiation of hydraulic fractures.The simulation results can provide valuable numerical insights for optimizing injection strategies for deep shale hydraulic fracturing.
文摘Process writing has been commonly recognized by scholars as an effective writing strategy and widely applied in the teaching of writing. The stages of process writing have been elaborated in this paper through the introduction of overseas core articles in this field from a scientific perspective combined with a cognition angle. Implications have been put forward to teachers at the end of this paper.
文摘In foreign language learning, many learners seem to have difficulty in reading accurately and efficiently so as to understand as much of a text as one needs in order to achieve one’s purpose. To help learners become more effective readers, it is crucial to develop relevant reading strategies in the light of their needs. This essay is intended to exploit how to help learners improve their second or foreign language reading strategies on the basis of a general understanding of the relevant literature. Holding the belief that the strategies chosen for the learners to be developed in the classroom should suit their needs, this essay mainly focuses on developing the learners’ top-down reading strategies such as predicting topics, which seems particularly relevant to the group of learners that I am familiar with. In an attempt to exemplify how to help learners of English develop their relevant reading strategies in English classes, a description of classroom procedures will be offered.
基金supported by the National Natural Science Foundation of China (Grant No. 71071119)the Fundamental Research Funds for the Central Universities
文摘By using a generalized fitness-dependent Moran process, an evolutionary model for symmetric 2 × 2 games in a well-mixed population with a finite size is investigated. In the model, the individuals' payoff accumulating from games is mapped into fitness using an exponent function. Both selection strength β and mutation rate ε are considered. The process is an ergodic birth-death process. Based on the limit distribution of the process, we give the analysis results for which strategy will be favoured when s is small enough. The results depend on not only the payoff matrix of the game, but also on the population size. Especially, we prove that natural selection favours the strategy which is risk-dominant when the population size is large enough. For arbitrary β and ε values, the 'Hawk-Dove' game and the 'Coordinate' game are used to illustrate our model. We give the evolutionary stable strategy (ESS) of the games and compare the results with those of the replicator dynamics in the infinite population. The results are determined by simulation experiments.
基金the National Natural Science Foundation of China(10571092)the major program of Key Research Institute of HumanitiesSocial Sciences at Universities(04JJD790006).
文摘In this article, a threshold dividend strategy is used for classical risk model. Under this dividend strategy, certain probability of ruin, which occurs in case of constant barrier strategy, is avoided. Using the strong Markov property of the surplus process and the distribution of the deficit in classical risk model, the survival probability for this model is derived, which is more direct than that in Asmussen(2000, P195, Proposition 1.10). The occupation time of non-dividend of this model is also discussed by means of Martingale method.
基金supported by the National High-Tech R&D Program (863 Program) under grant No. 2015AA01A705Beijing Municipal Science and Technology Commission research fund project under grant No. D151100000115002+1 种基金China Scholarship Council under grant No. 201406470038BUPT youth scientific research innovation program under grant No. 500401238
文摘Although small cell offloading technology can alleviate the congestion in macrocell, aggressively offloading data traffic from macrocell to small cell can also degrade the performance of small cell due to the heavy load. Because of collision and backoff, the degradation is significant especially in network with contention-based channel access, and finally decreases throughput of the whole network. To find an optimal fraction of traffic to be offloaded in heterogeneous network, we combine Markov chain with the Poisson point process model to analyze contention-based throughput in irregularly deployment networks. Then we derive the close-form solution of the throughput and find that it is a function of the transmit power and density of base stations.Based on this, we propose the load-aware offloading strategies via power control and base station density adjustment. The numerical results verify our analysis and show a great performance gain compared with non-load-aware offloading.
文摘This paper briefly reviews some significant learning strategies in L2 listening research.By pointing out both the feasibil ities and difficulties in implementing those strategies in Chinese EFL classrooms,it attempts to raise English language practitio ners'awareness of reforming the listening instruction and of utilizing strategic teaching approaches so as to enhance students'lis tening proficiency.
基金Supported by the National Natural Science Foundation of China under Grant Nos. 71071119 and 60574071
文摘Evolutionary game dynamics in finite size populations can be described by a fitness-dependent Wright- Fisher process. We consider symmetric 2×2 games in a well-mixed population. In our model, two parameters to describe the level of player's rationality and noise intensity in environment are introduced. In contrast with the fixation probability method that used in a noiseless case, the introducing of the noise intensity parameter makes the process an ergodic Markov process and based on the limit distribution of the process, we can analysis the evolutionary stable strategy (ESS) of the games. We illustrate the effects of the two parameters on the ESS of games using the Prisoner's dilemma games (PDG) and the snowdrift games (SG). We also compare the ESS of our model with that of the replicator dynamics in infinite size populations. The results are determined by simulation experiments.
基金supported by the National Natural Science Foundation of China (51175502)
文摘Testing is the premise and foundation of realizing equipment health management (EHM). To address the problem that the static periodic test strategy may cause deficient test or excessive test, a dynamic sequential test strategy (DSTS) for EHM is presented. Considering the situation that equipment health state is not completely observable in reality, a DSTS optimization method based on partially observable semi-Markov decision pro- cess (POSMDP) is proposed. Firstly, an equipment health state degradation model is constructed by Markov process, and the control limit maintenance policy is also introduced. Secondly, POSMDP is formulated in great detail. And then, POSMDP is converted to completely observable belief semi-Markov decision process (BSMDP) through belief state. The optimal equation and the corresponding optimal DSTS, which minimize the long-run ex- pected average cost per unit time, are obtained with BSMDP. The results of application in complex equipment show that the proposed DSTS is feasible and effective.
基金financially supported by the National Natural Science Foundation of China (Nos.50874014 and 51974023)the Fundamental Research Funds for Central Universities (No.FRF-BR-17-029A)。
文摘The quantitative evaluation of multi-process collaborative operation is of great significance for the improvement of production planning and scheduling in steelmaking–continuous casting sections(SCCSs). However, this evaluation is difficult since it relies on an in-depth understanding of the operating mechanism of SCCSs, and few existing methods can be used to conduct the evaluation, due to the lack of full-scale consideration of the multiple factors related to the production operation. In this study, three quantitative models were developed, and the multiprocess collaborative operation level was evaluated through the laminar-flow operation degree, the process matching degree, and the scheduling strategy availability degree. Based on the evaluation models for the laminar-flow operation and process matching levels, this study investigated the production status of two steelmaking plants, plants A and B, based on actual production data. The average laminar-flow operation(process matching) degrees of SCCSs were obtained as 0.638(0.610) and 1.000(0.759) for plants A and B, respectively, for the period of April to July 2019. Then, a scheduling strategy based on the optimization of the furnace-caster coordinating mode was suggested for plant A. Simulation experiments showed higher availability than the greedy-based and manual strategies. After the proposed scheduling strategy was applied,the average process matching degree of the SCCS of plant A increased by 4.6% for the period of September to November 2019. The multi-process collaborative operation level was improved with fewer adjustments and interruptions in casting.
基金financially supported by the National Natural Science Foundation of China(21938009)。
文摘Sulfate radical-advanced oxidation processes(SR-AOPs)are promising technologies for organic pollutants elimination.Heterogeneous metal-based catalysis has been widely studied and applied to activate peroxymonosulfate(PMS)for producing sulfate radicals.Developing highly efficient catalysts is crucial for future extensive use.Importantly,the catalytic activity is mainly determined by mass and electron transfer.This paper aims to overview the recent enhancement strategies for developing heterogeneous metalbased catalysts as effective PMS activators.The main strategies,including surface engineering,structural engineering,electronic modulation,external energy assistance,and membrane filtration enhancement,are summarized.The potential mechanisms for improving catalytic activity are also introduced.Finally,the challenges and future research prospects of heterogenous metal-based catalysis in SR-AOPs are proposed.This work is hoped to guide the rational design of highly efficient heterogenous catalysts in SR-AOPs.
基金Supported by the Open Fund of Key Laboratory of Modern Chinese Medicine Preparations,Ministry of Education,Jiangxi University of Traditional Chinese Medicine and First-class Discipline Construction Project of Jiangxi Province(JXSYLXK-ZHYAO009,JXSYLXK-ZHYAO010)。
文摘The quality standards for Fructus Comi have been established based on the effects of the manufacturing processes.Three critical process parameters(CPPs)of extraction,filtration,and concentration to prepare Fructus Comi concentrate were identified by Plackett-Burman design with a single batch of Fructus Corni,which were heating medium temperature,extraction time,and water addition.Morroniside yield,loganin yield,and dry matter yield were process critical quality attributes(CQAs).CPPs arranged with a Box-Behnken design were applied to treat different batches of Fructus Comi After constructing a model that included CPPs,material propertie s,and process CQAs,loganin content was found to be the critical material attribute(CMA).The design space was calculated with a probability method.According to the limits of process CQAs,the minimum content of loganin in Fructus Corni was calculated with an error propagation method,which was 6.92 mg·g^(-1).When the content of loganin in Fructus Corni reaches up to 6.92 mg·g^(-1),the material is considered high-quality and is most suitable for the process.High-quality material can be used for production of Fructus Comi concentrate.This method can also be used to set material quality standards for other Chinese medicines.