In order to help athletes optimize their performances in competitions while prevent overtraining and the risk of overuse injuries,it is important to develop science-based strategies for optimally designing training pr...In order to help athletes optimize their performances in competitions while prevent overtraining and the risk of overuse injuries,it is important to develop science-based strategies for optimally designing training programs.The purpose of the present study is to develop a novel method by the combined use of optimal control theory and a training-performance model for designing optimal training programs,with the hope of helping athletes achieve the best performance exactly on the competition day while properly manage training load during the training course for preventing overtraining.The training-performance model used in the proposed optimal control framework is a conceptual extension of the Banister impulse-response model that describes the dynamics of performance,training load(served as the control variable),fitness(the overall positive effects on performance),and fatigue(the overall negative effects on performance).The objective functional of the proposed optimal control framework is to maximize the fitness and minimize the fatigue on the competition day with the goal of maximizing the performance on the competition day while minimizing the cumulative training load during the training course.The Forward-Backward Sweep Method is used to solve the proposed optimal control framework to obtain the optimal solutions of performance,training load,fitness,and fatigue.The simulation results show that the performance on the competition day is higher while the cumulative training load during the training course is lower with using optimal control theory than those without,successfully showing the feasibility and benefits of using the proposed optimal control framework to design optimal training programs for helping athletes achieve the best performance exactly on the competition day while properly manage training load during the training course for preventing overtraining.The present feasibility study lays the foundation of the combined use of optimal control theory and training-performance models to design personalized optimal training programs in real applications in athletic training and sports science for helping athletes achieve the best performances in competitions while prevent overtraining and the risk of overuse injuries.展开更多
Assessment exercises constitute a crucial component of the teaching and learning process,serving the purpose of gauging the degree to which learning objectives have been accomplished.This study aims to assess the math...Assessment exercises constitute a crucial component of the teaching and learning process,serving the purpose of gauging the degree to which learning objectives have been accomplished.This study aims to assess the mathematics performance of Grade 7 learners using the 50-30-20 exercise.Specifically,this study seeks to determine the learners’pre-test and post-test mean scores,identify significant differences between the pre-test and post-test results,evaluate learners’exercises,and propose enhanced exercises.The research employs a quasi-experimental design,with 40 Grade 7 learners in the school year 2023-2024 as participants,selected through purposive non-random sampling.Statistical data analysis involves the use of mean,standard deviation,paired t-test,and Cohen’s D effect size.Ethical considerations were paramount,as evidenced by a letter of authorization from the school head outlining the strict adherence to voluntary participation,informed parental consent,anonymity,confidentiality,risk mitigation,results-sharing protocols,and the commitment to keeping research data confidential.The data yielded a remarkable outcome:the experimental group exhibited improvement in both the pre-test and post-test.This result substantiates the initial objective of the study,showcasing a noteworthy and favorable performance among the participants.Consequently,it suggests that a majority of the participants strongly agree that the 50-30-20 exercises contribute to enhancing their understanding and problem-solving skills,as well as their ability to grasp mathematical concepts and improve their overall performance in mathematics.Therefore,the 50-30-20 exercises not only facilitated students in understanding mathematics lessons but were also aligned with the Department of Education’s development plan.展开更多
Learning mathematics requires an effective and strategic teaching approach.This study aimed to assess the mathematics performance of the learners with the implementation of the numeracy enhancement strategy QD2R(Quest...Learning mathematics requires an effective and strategic teaching approach.This study aimed to assess the mathematics performance of the learners with the implementation of the numeracy enhancement strategy QD2R(Questions,Drills,Repetition,and Recitation)and to propose a strategy implementation plan to elevate their performances.This study employed the use of a quasi-experimental research design,purposive sampling with 70 Grade 10 students of Lian National High School who were distributed equally to control and treatment groups.The pre-test and post-test results were statistically analyzed using independent and paired sample t-tests,and a survey questionnaire was examined by getting the mean and standard deviation.The results indicated that better performance was achieved by the students from the treatment group compared to the students from the control group,as revealed by the Mean Percentage Score(MPS)results,mean scores,and P values of their pre-test and post-test scores.The learners’perception of the implementation of this strategy was to a great extent,wherein it was perceived to be more helpful in concepts related to understanding the lesson compared to concepts related to developing their attitude and skills.Moreover,the proposed implementation plan of numeracy enhancement strategy QD2R had three expected outcomes:elevated understanding and performance in mathematics lessons;modified strategy to focus on the development of attitude and skills towards mathematics;and refined and well-implemented QD2R strategy in teaching mathematics.Relative to these expected outcomes,appropriate measures,timeframe,and resources of each were comprehensively formulated.展开更多
A mathematical model is set to evaluate the overall centrifugal pumpingsystem using asynchronous motor as power. This method can be used to affirm system performanceaccording the transform and the aberrance of interio...A mathematical model is set to evaluate the overall centrifugal pumpingsystem using asynchronous motor as power. This method can be used to affirm system performanceaccording the transform and the aberrance of interior parameters and exterior performance curves soas to give a reference to the equipment amelioration. The analysis of emulation experiment datasuggests the model is effectively used.展开更多
Mathematics is considered by many students as a difficult academic subject. To improve their performance, various learning strategies are employed by teachers abandoning the conventional method. This study focused on ...Mathematics is considered by many students as a difficult academic subject. To improve their performance, various learning strategies are employed by teachers abandoning the conventional method. This study focused on the cooperative learning as a method to enhance level of performance of grade 10 mathematics students in the Philippines. It looked into the method and how it influenced students’ performance. By using a quasi-experimental research method, the following results are generated: 1) the method positively improved the performance in mathematics of the control and experimental groups;2) while effectiveness assessment showed a highly effective result;and 3) the application of the method showed a positive impact on the participants as shown by their positive perception of the subject mathematics.展开更多
In recent years,the rapid development of artificial intelligence(AI)technology has been driving profound transformations in higher education.As a fundamental course in science and engineering disciplines,Advanced Math...In recent years,the rapid development of artificial intelligence(AI)technology has been driving profound transformations in higher education.As a fundamental course in science and engineering disciplines,Advanced Mathematics plays a crucial role in cultivating students’logical thinking and innovative capabilities.However,the current teaching models exhibit significant shortcomings in fostering students’ability to identify and solve problems,primarily reflected in the monotony of teaching content,the limitations of students’thinking,and the constraints of instructional methods.In response to these issues,this paper proposes an AI-based teaching approach for Advanced Mathematics.By utilizing scenario simulations to guide students in discovering problems and employing modeling tools to assist them in solving problems in real time,the study constructs a comprehensive teaching model that spans the entire process from problem identification to problem resolution.Research findings indicate that the application of AI technology can effectively enhance students’abilities in problem awareness,logical reasoning,and creative thinking.This study provides both theoretical support and practical reference for the reform of Advanced Mathematics education and the innovation of higher-level talent cultivation models.展开更多
Mathematics as a basic subject of many disciplines to cultivate students 'way of thinking, to cultivate students' mathematical problem solving ability needs from students review ability, plus teachers teaching...Mathematics as a basic subject of many disciplines to cultivate students 'way of thinking, to cultivate students' mathematical problem solving ability needs from students review ability, plus teachers teaching activities pay attention to students' thinking ability training, including logical thinking ability and spatial composition ability, finally teach high school students master digital combination, under common methods, this will be throughout the mathematics learning.展开更多
This study aimed to develop real-life performance-based tasks in Business Mathematics (RLPBTs) following the ADDIE’s model of instructional development. Using the descriptive-developmental research design, the study ...This study aimed to develop real-life performance-based tasks in Business Mathematics (RLPBTs) following the ADDIE’s model of instructional development. Using the descriptive-developmental research design, the study developed RLPBTS with mathematics experts, mathematics department head, bank manager, mathematics teachers, and students as respondents. The RLPBTs consist of instructional plans. Each instructional plan has these components: Introduction, Learning Competency, Learning Outcome, Task Execution, Scoring Guide, and Generalization. The design and content of the instructional plans were assessed as very good. On the other hand, the design and execution of the Tasks were assessed as favorable. Grade 11 students also agreed that real-life performance-based tasks helped them understand better concepts in business mathematics. They claimed that they enjoyed the tasks because of the inclusion of real-life situations that they simulated. The use of the RLPBTs provides another innovation in the teaching and learning concepts in Business Mathematics.展开更多
As a key component in rotating machinery, the operating reliability of bearing influences the performance and service life of the equipment directly. In order to describe bearing performance degradation(BPD) process e...As a key component in rotating machinery, the operating reliability of bearing influences the performance and service life of the equipment directly. In order to describe bearing performance degradation(BPD) process effectively, an assessment approach combining extension and ensemble empirical mode decomposition(EEMD) was proposed. First, the extension was utilized to construct the matter-element of bearing operating state, and the energy moment of intrinsic mode functions(IMFs) was used as characteristic parameter of the matter-element. Then, to determine classical domains of characteristic parameters, the mathematical statistics method was adopted. Finally, the BPD was analyzed qualitatively and quantitatively according to the comprehensive correlation degree of bearing current operating state related to its healthy state. The analytic results of bearing test-rig show that the proposed method indicates the incipient fault approximately occurring in the 81 st hour, and the method also quantitatively presents the degree of BPD. By contrast, the BPD assessment based on time-domain features extraction method could not achieve the above two results effectively.展开更多
Cemented paste backfill(CPB)technology is a green mining method used to control underground goaves and tailings ponds.The curing process of CPB in the stope is the product of a thermo-hydro-mechanical-chemical multi-f...Cemented paste backfill(CPB)technology is a green mining method used to control underground goaves and tailings ponds.The curing process of CPB in the stope is the product of a thermo-hydro-mechanical-chemical multi-field performance interaction.At present,research on the multi-field performance of CPB mainly includes indoor similar simulation experiments,in-situ multi-field performance monitoring experiments,multi-field performance coupling model construction of CPB,and numerical simulation of the multi-field performance of CPB.Because it is hard to study the in-situ multi-field performance of CPB in the real stope,most current research on in-situ multi-field performance adopts the numerical simulation method.By simulating the conditions of CPB in the real stope(e.g.,maintenance environment,stope geometry,drainage conditions,and barricade and backfilling rates),the multi-field performance of CPB is further studied.This paper summarizes the mathematical models employed in the numerical simulation and lists the engineering application cases of numerical simulation in the in-situ multi-field performance of CPB.Finally,it proposes that the multi-field performance of CPB needs to strengthen the theoretical study of multi-field performance,form the strength design criterion based on the multi-field performance of CPB,perform a full-range numerical simulation of the multi-field performance of CPB,develop a pre-warning technology for the CPB safety of CPB,develop automatic and wireless sensors for the multi-field performance monitoring of CPB,and realize the application and popularization of CPB monitoring technology.展开更多
This study addresses heat transfer performance of various configurations of coiled non-circular tubes, e.g., in-plane spiral ducts, helical spiral ducts, and conical spiral ducts. The laminar flow of a Newtonian fluid...This study addresses heat transfer performance of various configurations of coiled non-circular tubes, e.g., in-plane spiral ducts, helical spiral ducts, and conical spiral ducts. The laminar flow of a Newtonian fluid in helical coils made of square cross section tubes is simulated using the computational fluid dynamic approach. The effects of tube Reynolds number, fluid Prandtl number, coil diameter, etc., are quantified and discussed. Both constant wall temperature and constant heat flux conditions are simulated. The effect of in-plane coil versus a cylindrical design of constant coil, as well as a conical coil design is discussed. Results are compared with those for a straight square tube of the same length as that used to form the coils. Advantages and limitations of using coiled tubes are discussed in light of the numerical results.展开更多
This study investigated the effectiveness of spatial-visualization-based instruction on the mathematical problem-solving performance of 35 mathematics education students using one-group pretest-posttest quasi-experime...This study investigated the effectiveness of spatial-visualization-based instruction on the mathematical problem-solving performance of 35 mathematics education students using one-group pretest-posttest quasi-experimental design. It also aimed to describe how spatial visualization is applied in solving mathematical problems. The findings of the study revealed that spatial-visualization-based instruction improved the mathematical problem-solving performance of students. The spatial-visualization ability can be applied in solving mathematical problems.展开更多
The structure and operational principle on a new type reversing valve of hydraulic breaker are introduced. The nonlinear mathematic model and simulation model of the new type reversing valve are built. The dynamic sim...The structure and operational principle on a new type reversing valve of hydraulic breaker are introduced. The nonlinear mathematic model and simulation model of the new type reversing valve are built. The dynamic simulation research of the new type reversing valve is conducted. The effects of the system parameters on the working performance are researched systematically and deeply. The regular understanding on the motion of the reversing valve is obtained, which provides theoretical basis for the innovation and manufacturing of a new generation of hydraulic breaker reversing valve.展开更多
The construction of underground natural gas storage is one of the most reasonable and effective ways for basically surmounting city seasonal peak shaving and stabilizing peak waving. Owing to the heterogeneity of geol...The construction of underground natural gas storage is one of the most reasonable and effective ways for basically surmounting city seasonal peak shaving and stabilizing peak waving. Owing to the heterogeneity of geological structure used as underground natural gas storage and different capacities of storing and transmitting fluid in reservoir, it is necessary make a reasonable proration for each member of the injection and production wells within the storage during peak shaving. In this paper, through analyzing the injection production performance characteristics of the underground natural gas storage in depleted gas field, an accurate mathematical model of the underground gas storage of depleted gas field is set up; characteristics of the storage performance and permeating processes were studied,history processes of underground gas storage were stimulated and major influence factors were analyzed. Specific and typical examples from actural data are included to demonstrate the relevance of the method to simulation of storage operation.展开更多
The continuous affinity- recycle extraction (CARE) process is extended ic a system with ultrafiltration membranes. The mathematical model of the process is established by taking into account membrane rejections to th...The continuous affinity- recycle extraction (CARE) process is extended ic a system with ultrafiltration membranes. The mathematical model of the process is established by taking into account membrane rejections to the components in a crude mixture. The process performance, defined as concentration factor (CF ), purification factor (PF ) and recovery yield (REC), is analyzed by computer simulations. The results show that CF and REC increase, but PF decreases with the membrane rejection. It is likely that optimum operating conditions exist to give the best process performance because the increases in eluant and affinity-recycle flow rate improve REC but decrease PF.展开更多
基金funded by the National Science and Technology Council,grant number NSTC 113-2221-E-002-136-.
文摘In order to help athletes optimize their performances in competitions while prevent overtraining and the risk of overuse injuries,it is important to develop science-based strategies for optimally designing training programs.The purpose of the present study is to develop a novel method by the combined use of optimal control theory and a training-performance model for designing optimal training programs,with the hope of helping athletes achieve the best performance exactly on the competition day while properly manage training load during the training course for preventing overtraining.The training-performance model used in the proposed optimal control framework is a conceptual extension of the Banister impulse-response model that describes the dynamics of performance,training load(served as the control variable),fitness(the overall positive effects on performance),and fatigue(the overall negative effects on performance).The objective functional of the proposed optimal control framework is to maximize the fitness and minimize the fatigue on the competition day with the goal of maximizing the performance on the competition day while minimizing the cumulative training load during the training course.The Forward-Backward Sweep Method is used to solve the proposed optimal control framework to obtain the optimal solutions of performance,training load,fitness,and fatigue.The simulation results show that the performance on the competition day is higher while the cumulative training load during the training course is lower with using optimal control theory than those without,successfully showing the feasibility and benefits of using the proposed optimal control framework to design optimal training programs for helping athletes achieve the best performance exactly on the competition day while properly manage training load during the training course for preventing overtraining.The present feasibility study lays the foundation of the combined use of optimal control theory and training-performance models to design personalized optimal training programs in real applications in athletic training and sports science for helping athletes achieve the best performances in competitions while prevent overtraining and the risk of overuse injuries.
文摘Assessment exercises constitute a crucial component of the teaching and learning process,serving the purpose of gauging the degree to which learning objectives have been accomplished.This study aims to assess the mathematics performance of Grade 7 learners using the 50-30-20 exercise.Specifically,this study seeks to determine the learners’pre-test and post-test mean scores,identify significant differences between the pre-test and post-test results,evaluate learners’exercises,and propose enhanced exercises.The research employs a quasi-experimental design,with 40 Grade 7 learners in the school year 2023-2024 as participants,selected through purposive non-random sampling.Statistical data analysis involves the use of mean,standard deviation,paired t-test,and Cohen’s D effect size.Ethical considerations were paramount,as evidenced by a letter of authorization from the school head outlining the strict adherence to voluntary participation,informed parental consent,anonymity,confidentiality,risk mitigation,results-sharing protocols,and the commitment to keeping research data confidential.The data yielded a remarkable outcome:the experimental group exhibited improvement in both the pre-test and post-test.This result substantiates the initial objective of the study,showcasing a noteworthy and favorable performance among the participants.Consequently,it suggests that a majority of the participants strongly agree that the 50-30-20 exercises contribute to enhancing their understanding and problem-solving skills,as well as their ability to grasp mathematical concepts and improve their overall performance in mathematics.Therefore,the 50-30-20 exercises not only facilitated students in understanding mathematics lessons but were also aligned with the Department of Education’s development plan.
文摘Learning mathematics requires an effective and strategic teaching approach.This study aimed to assess the mathematics performance of the learners with the implementation of the numeracy enhancement strategy QD2R(Questions,Drills,Repetition,and Recitation)and to propose a strategy implementation plan to elevate their performances.This study employed the use of a quasi-experimental research design,purposive sampling with 70 Grade 10 students of Lian National High School who were distributed equally to control and treatment groups.The pre-test and post-test results were statistically analyzed using independent and paired sample t-tests,and a survey questionnaire was examined by getting the mean and standard deviation.The results indicated that better performance was achieved by the students from the treatment group compared to the students from the control group,as revealed by the Mean Percentage Score(MPS)results,mean scores,and P values of their pre-test and post-test scores.The learners’perception of the implementation of this strategy was to a great extent,wherein it was perceived to be more helpful in concepts related to understanding the lesson compared to concepts related to developing their attitude and skills.Moreover,the proposed implementation plan of numeracy enhancement strategy QD2R had three expected outcomes:elevated understanding and performance in mathematics lessons;modified strategy to focus on the development of attitude and skills towards mathematics;and refined and well-implemented QD2R strategy in teaching mathematics.Relative to these expected outcomes,appropriate measures,timeframe,and resources of each were comprehensively formulated.
文摘A mathematical model is set to evaluate the overall centrifugal pumpingsystem using asynchronous motor as power. This method can be used to affirm system performanceaccording the transform and the aberrance of interior parameters and exterior performance curves soas to give a reference to the equipment amelioration. The analysis of emulation experiment datasuggests the model is effectively used.
文摘Mathematics is considered by many students as a difficult academic subject. To improve their performance, various learning strategies are employed by teachers abandoning the conventional method. This study focused on the cooperative learning as a method to enhance level of performance of grade 10 mathematics students in the Philippines. It looked into the method and how it influenced students’ performance. By using a quasi-experimental research method, the following results are generated: 1) the method positively improved the performance in mathematics of the control and experimental groups;2) while effectiveness assessment showed a highly effective result;and 3) the application of the method showed a positive impact on the participants as shown by their positive perception of the subject mathematics.
基金supported by the 2023 Teaching Reform and Research Project of China University of Petroleum(Beijing),Karamay Campus(Grant No.JG2023048)the 2024 National Undergraduate Innovation and Entrepreneurship Training Program of China(Project No.202419414009)the 2024 General Program of the Natural Science Foundation of Xinjiang Uygur Autonomous Region(Grant No.2024D01A160).
文摘In recent years,the rapid development of artificial intelligence(AI)technology has been driving profound transformations in higher education.As a fundamental course in science and engineering disciplines,Advanced Mathematics plays a crucial role in cultivating students’logical thinking and innovative capabilities.However,the current teaching models exhibit significant shortcomings in fostering students’ability to identify and solve problems,primarily reflected in the monotony of teaching content,the limitations of students’thinking,and the constraints of instructional methods.In response to these issues,this paper proposes an AI-based teaching approach for Advanced Mathematics.By utilizing scenario simulations to guide students in discovering problems and employing modeling tools to assist them in solving problems in real time,the study constructs a comprehensive teaching model that spans the entire process from problem identification to problem resolution.Research findings indicate that the application of AI technology can effectively enhance students’abilities in problem awareness,logical reasoning,and creative thinking.This study provides both theoretical support and practical reference for the reform of Advanced Mathematics education and the innovation of higher-level talent cultivation models.
文摘Mathematics as a basic subject of many disciplines to cultivate students 'way of thinking, to cultivate students' mathematical problem solving ability needs from students review ability, plus teachers teaching activities pay attention to students' thinking ability training, including logical thinking ability and spatial composition ability, finally teach high school students master digital combination, under common methods, this will be throughout the mathematics learning.
文摘This study aimed to develop real-life performance-based tasks in Business Mathematics (RLPBTs) following the ADDIE’s model of instructional development. Using the descriptive-developmental research design, the study developed RLPBTS with mathematics experts, mathematics department head, bank manager, mathematics teachers, and students as respondents. The RLPBTs consist of instructional plans. Each instructional plan has these components: Introduction, Learning Competency, Learning Outcome, Task Execution, Scoring Guide, and Generalization. The design and content of the instructional plans were assessed as very good. On the other hand, the design and execution of the Tasks were assessed as favorable. Grade 11 students also agreed that real-life performance-based tasks helped them understand better concepts in business mathematics. They claimed that they enjoyed the tasks because of the inclusion of real-life situations that they simulated. The use of the RLPBTs provides another innovation in the teaching and learning concepts in Business Mathematics.
基金Project(51575232)supported by the National Natural Science Foundation of ChinaProject(201215020)supported by the Natural Science Foundation of Jilin Province,China
文摘As a key component in rotating machinery, the operating reliability of bearing influences the performance and service life of the equipment directly. In order to describe bearing performance degradation(BPD) process effectively, an assessment approach combining extension and ensemble empirical mode decomposition(EEMD) was proposed. First, the extension was utilized to construct the matter-element of bearing operating state, and the energy moment of intrinsic mode functions(IMFs) was used as characteristic parameter of the matter-element. Then, to determine classical domains of characteristic parameters, the mathematical statistics method was adopted. Finally, the BPD was analyzed qualitatively and quantitatively according to the comprehensive correlation degree of bearing current operating state related to its healthy state. The analytic results of bearing test-rig show that the proposed method indicates the incipient fault approximately occurring in the 81 st hour, and the method also quantitatively presents the degree of BPD. By contrast, the BPD assessment based on time-domain features extraction method could not achieve the above two results effectively.
基金financially supported by the National Natural Science Foundation of China(No.52130404)the State Key Laboratory for GeoMechanics and Deep Underground Engineering China University of Mining&Technology,Beijing(No.SKLGDUEK2127)+1 种基金the Fundamental Research Funds for the Central Universities(Nos.FRF-TP-19-002C2Z,FRF-IDRY-20-031)and the Fundamental Research Funds for the Central Universities and the Youth Teacher International Exchange&Growth Program(No.QNXM20220002)。
文摘Cemented paste backfill(CPB)technology is a green mining method used to control underground goaves and tailings ponds.The curing process of CPB in the stope is the product of a thermo-hydro-mechanical-chemical multi-field performance interaction.At present,research on the multi-field performance of CPB mainly includes indoor similar simulation experiments,in-situ multi-field performance monitoring experiments,multi-field performance coupling model construction of CPB,and numerical simulation of the multi-field performance of CPB.Because it is hard to study the in-situ multi-field performance of CPB in the real stope,most current research on in-situ multi-field performance adopts the numerical simulation method.By simulating the conditions of CPB in the real stope(e.g.,maintenance environment,stope geometry,drainage conditions,and barricade and backfilling rates),the multi-field performance of CPB is further studied.This paper summarizes the mathematical models employed in the numerical simulation and lists the engineering application cases of numerical simulation in the in-situ multi-field performance of CPB.Finally,it proposes that the multi-field performance of CPB needs to strengthen the theoretical study of multi-field performance,form the strength design criterion based on the multi-field performance of CPB,perform a full-range numerical simulation of the multi-field performance of CPB,develop a pre-warning technology for the CPB safety of CPB,develop automatic and wireless sensors for the multi-field performance monitoring of CPB,and realize the application and popularization of CPB monitoring technology.
文摘This study addresses heat transfer performance of various configurations of coiled non-circular tubes, e.g., in-plane spiral ducts, helical spiral ducts, and conical spiral ducts. The laminar flow of a Newtonian fluid in helical coils made of square cross section tubes is simulated using the computational fluid dynamic approach. The effects of tube Reynolds number, fluid Prandtl number, coil diameter, etc., are quantified and discussed. Both constant wall temperature and constant heat flux conditions are simulated. The effect of in-plane coil versus a cylindrical design of constant coil, as well as a conical coil design is discussed. Results are compared with those for a straight square tube of the same length as that used to form the coils. Advantages and limitations of using coiled tubes are discussed in light of the numerical results.
文摘This study investigated the effectiveness of spatial-visualization-based instruction on the mathematical problem-solving performance of 35 mathematics education students using one-group pretest-posttest quasi-experimental design. It also aimed to describe how spatial visualization is applied in solving mathematical problems. The findings of the study revealed that spatial-visualization-based instruction improved the mathematical problem-solving performance of students. The spatial-visualization ability can be applied in solving mathematical problems.
文摘The structure and operational principle on a new type reversing valve of hydraulic breaker are introduced. The nonlinear mathematic model and simulation model of the new type reversing valve are built. The dynamic simulation research of the new type reversing valve is conducted. The effects of the system parameters on the working performance are researched systematically and deeply. The regular understanding on the motion of the reversing valve is obtained, which provides theoretical basis for the innovation and manufacturing of a new generation of hydraulic breaker reversing valve.
文摘The construction of underground natural gas storage is one of the most reasonable and effective ways for basically surmounting city seasonal peak shaving and stabilizing peak waving. Owing to the heterogeneity of geological structure used as underground natural gas storage and different capacities of storing and transmitting fluid in reservoir, it is necessary make a reasonable proration for each member of the injection and production wells within the storage during peak shaving. In this paper, through analyzing the injection production performance characteristics of the underground natural gas storage in depleted gas field, an accurate mathematical model of the underground gas storage of depleted gas field is set up; characteristics of the storage performance and permeating processes were studied,history processes of underground gas storage were stimulated and major influence factors were analyzed. Specific and typical examples from actural data are included to demonstrate the relevance of the method to simulation of storage operation.
文摘The continuous affinity- recycle extraction (CARE) process is extended ic a system with ultrafiltration membranes. The mathematical model of the process is established by taking into account membrane rejections to the components in a crude mixture. The process performance, defined as concentration factor (CF ), purification factor (PF ) and recovery yield (REC), is analyzed by computer simulations. The results show that CF and REC increase, but PF decreases with the membrane rejection. It is likely that optimum operating conditions exist to give the best process performance because the increases in eluant and affinity-recycle flow rate improve REC but decrease PF.
