Around the world,there has been a notable shift toward the use of renewable energy technology due to the growing demand for energy and the ongoing depletion of conventional resources,such as fossil fuels.Following thi...Around the world,there has been a notable shift toward the use of renewable energy technology due to the growing demand for energy and the ongoing depletion of conventional resources,such as fossil fuels.Following this worldwide trend,Brunei’s government has initiated several strategic programs aimed at encouraging the establishment of energy from renewable sources in the nation’s energy mix.These initiatives are designed not only to support environmental sustainability but also to make energy from renewable sources increasingly competitive in comparison to more conventional energy sources like gas and oil,which have historically dominated Brunei’s energy market.The optimization of a hybrid energy system that combines diesel generators,solar photovoltaic(PV)panels,and the national power grid is the focus of this study.The objective is to identify the most cost-effective and environmentally sustainable configuration that can reliably meet local energy demands.During optimization,several configuration was tried and tested,including only grid,PV and Grid and PV-generator.HOMER(Hybrid Optimization of Multiple Energy Resources)software,a popular simulation tool that makes it possible to simulate and analyze hybrid energy systems,is utilized in the optimization process.Inside the HOMER Pro optimization,various system configuration is taken into account for the optimization.While simulating,it takes into account different combinations of components such as solar panels,wind turbines and batteries.Later on,it is being ranked by different factors such as net present cost(NPC),Cost of Energy(COE),etc.A comprehensive techno-economic research is carried out to evaluate various system configurations,considering key performance indicators such as total energy generation cost,operational expenditure,and greenhouse gas emissions.The results provide valuable insights into how renewable-based hybrid systems can reduce environmental impact while maintaining economic viability,supporting Brunei’s broader goals of energy diversification and sustainability.The study also emphasizes how such hybrid systems could be scaled for off-grid and rural populations in Brunei,where a dependable electricity supply is still a problem.Furthermore,sensitivity analyses were performed to evaluate the effects of variations in solar irradiation,load demand,and fuel prices on the overall system performance.Policymakers and energy planners can use these insights to help them make data-driven decisions about future investments in infrastructure for renewable energy.展开更多
With the extending scale of agricultural production,the treatment and utilization of waste have become increasingly serious environmental problem.Taking city garden and Zhongnan pasture in Pujiang Town of Minhang Dist...With the extending scale of agricultural production,the treatment and utilization of waste have become increasingly serious environmental problem.Taking city garden and Zhongnan pasture in Pujiang Town of Minhang District in Shanghai for example,according to the analysis on discharge characteristic of waste and balance of resources and energy utilization,mixed anaerobic digestion was chosen to dispose waste based on government guidance and feasibility analysis of project,and the combining disposal and resource utilization of waste were realized in two enterprises,providing reference for close cases.展开更多
Objective:To assess the feasibility of coronary angiography by transradial approach with 4F catheter.Methods:The procedural details,picture quality,local complication were recorded for coronary by transradial approach...Objective:To assess the feasibility of coronary angiography by transradial approach with 4F catheter.Methods:The procedural details,picture quality,local complication were recorded for coronary by transradial approach with 4F catheter in 138 patients.Results:The success rate of angiography was 97.7%;fluoroscopy time was(5.05±3.23)minutes,total procedural time was(20.51±3.37)minutes;the incidence of dislodgement,excessive engagement of either coronary artery was 7.8%,9.4%,repectively;the angiographic scores for left anterior descending,circumflex and right coronary arteries were(2.87±0.40),(2.88±0.39),(2.90±0.35),respectively.The spasm complication occurred 4.3% in radial artery and 1.5% in coronary artery.There were no occlusion of radial artery during follow up.Conclusion:4F catheter could be the first chosen in some selecting patients for its nice maneuverability,fine images and fewer vascular complications.展开更多
In order to monitor the working state of piston motor and measure its instantaneous rotation speed accurately, the measuring principle and method of instantaneous rotation speed based on industrial personal computer a...In order to monitor the working state of piston motor and measure its instantaneous rotation speed accurately, the measuring principle and method of instantaneous rotation speed based on industrial personal computer and data acquisition card are introduced, and the major error source, influence mechanism and processing method of data quantization error are dis- cussed. By means of hybrid programming approach of LabVIEW and MATLAB, the instantaneous rotation speed measurement system for the piston motor in variable speed hydraulic system is designed. The simulation and experimental results show that the designed instantaneous speed measurement system is feasible. Furthermore, the sampling frequency has an important influ- ence on the instantaneous rotation speed measurement of piston motor and higher sampling frequency can lower quantization er- ror and improve measurement accuracy.展开更多
Based on the decline in exploitation of coal resources, steep coal seam mining and mining face tensions continue to explore the feasibility analysis of steeply inclined faces in the gob. One of the key factors in util...Based on the decline in exploitation of coal resources, steep coal seam mining and mining face tensions continue to explore the feasibility analysis of steeply inclined faces in the gob. One of the key factors in utilizing the technology of gob-side entry retaining in steep coal seams is to safely and effectively prevent caving rock blocks from rushing into the gob-side entry by sliding downwards along levels. Using theoretical analysis and field methods, we numerically simulated the mining process on a fully-mechanized face in a steep coal seam. The stress and deformation process of roof strata has been analyzed, and the difficulty of utilizing the technology is considered and combined with practice in a steep working face in Lvshuidong mine. The feasibility of utilizing the technology of gob-side entry retaining in a steep coal seam has been recognised. We propose that roadways along the left lane offshoot body use a speciallymade reinforced steel dense net to build a dense rock face at the lower head. The results show that the lane offshoot branch creates effective roof control, safe conditions for roadway construction workers, and practical application of steeply inclined gob.展开更多
Laser tracking system （LTS） is an advanced device for large size 3D coordinates measuring with the advantages of broad range, high speed and high accuracy. However, its measuring accuracy is highly dominated by the ...Laser tracking system （LTS） is an advanced device for large size 3D coordinates measuring with the advantages of broad range, high speed and high accuracy. However, its measuring accuracy is highly dominated by the geometric errors of the tracking mirror mechanism. Proper calibration of LTS is essential prior to the use of it for metrology. A kinematics model that describes not only the motion but also the geometric variations of LTS is developed. Through error analysis of the proposed model, it is claimed that gimbals axis misalignments and tracking mirror center off-set are the key contributors to measuring errors of LTS. A self-calibration method is presented of calibrating LTS with planar constraints. Various calibration strategies utilizing single-plane and multiple-plane constraints are proposed for different situations. For each calibration strategy, issues about the error parameter estimation of LTS are exploded to find out in which conditions these parameters can be uniquely estimated. Moreover, these conditions reveal the applicability of the planar constraints to LTS self-calibration. Intensive studies have been made to check validity of the theoretical results. The results show that the measuring accuracy of LTS has increased by 5 times since this technique for calibration is used.展开更多
This paper presents a non-smooth multibody dynamic formulation and error analysis of an antenna pointing mechanism including frictional spatial revolute joints(FSRJs)with small clearance in the framework of the specia...This paper presents a non-smooth multibody dynamic formulation and error analysis of an antenna pointing mechanism including frictional spatial revolute joints(FSRJs)with small clearance in the framework of the special Euclidian group SE(3).The formulation leads to an inertial frame-invariant,a compact and unified description for rigid bodies and spatial revolute joints(SRJs).The geometric constraint of the bearing is covered by four open semi-cylinders,which can be treated as bilateral constraints assuming that the impact effects are negligible.The frictional contact problem is formulated as a horizontal linear complementary problem(HLCP),which is embedded in the Lie-group integration scheme.Error of the antenna pointing mechanism is modeled by means of the adjoint transformation and POE-based formula.The evolution of errors is obtained through the solution of non-smooth dynamics.The obtained numerical results illustrate the influences of FSRJs in dynamics modeling and error analysis of the antenna pointing mechanism.展开更多
Feasibility analysis of soft constraints for input and output variables is critical for model predictive control(MPC).When encountering the infeasible situation, some way should be found to adjust the constraints to g...Feasibility analysis of soft constraints for input and output variables is critical for model predictive control(MPC).When encountering the infeasible situation, some way should be found to adjust the constraints to guarantee that the optimal control law exists. For MPC integrated with soft sensor, considering the soft constraints for critical variables additionally makes it more complicated and difficult for feasibility analysis and constraint adjustment. Therefore, the main contributions are that a linear programming approach is proposed for feasibility analysis, and the corresponding constraint adjustment method and procedure are given as well. The feasibility analysis gives considerations to the manipulated, secondary and critical variables, and the increment of manipulated variables as well. The feasibility analysis and the constraint adjustment are conducted in the entire control process and guarantee the existence of optimal control. In final, a simulation case confirms the contributions in this paper.展开更多
On Mauritania’s northern coast, wind and solar resources are abundant and must be used effectively. These resources have the potential to completely or partially replace the existing or projected diesel generators. T...On Mauritania’s northern coast, wind and solar resources are abundant and must be used effectively. These resources have the potential to completely or partially replace the existing or projected diesel generators. The main objective of this case study is to study the possibility of using a hybrid system (HS) of the type (diesel, wind and storage). The most important part of this case study intended for this area will be to add the solar in a first phase and then the incorporation of an interconnection with the nearby network in a second phase. This interconnection will be secured by mean of medium voltage lines of 33 kV, where the nearest point is located 35 km away. Indeed, the study of the optimization model is carried out through Homer, which was developed by National Renewable Energy Laboratory [NREL]. Thus, it should be noted that the HS is analyzed on the basis of costs ($/kW) and price ($/kWh) and greenhouse gas emissions. Therefore, in order to achieve these techno-economic optimization objectives, this paper introduces a sensitivity analysis that has been proposed to determine the effect of costs on each HS configuration. In the end, HSs are needed for maximum use of renewable resources at the studied site for an uninterrupted power supply.展开更多
Cropping systems worldwide have been affected by the current trend in global warming and the optimization of cropping systems is an important area of research in the transition of agricultural land. The Loess Plateau ...Cropping systems worldwide have been affected by the current trend in global warming and the optimization of cropping systems is an important area of research in the transition of agricultural land. The Loess Plateau is a typical ecologically fragile region with the most serious soil erosion in China. We carried out a field experiment in Yan’an city on the Loess Plateau to explore the effect of sowing date on crop growth and yield. We then analyzed the feasibility of a double-cropping system by considering climatic adaptability, ecological suitability and economic viability. Our results showed that different sowing dates resulted in significant differences in crop growth and that appropriate early sowing can result in higher crop yields for early maturing varieties. We showed that double-cropping systems of sweet maize(Zea mays)–forage rape and feed maize–forage rape are feasible on the Loess Plateau. We discuss the implications for the efficient use of farmland, which is important in guiding agricultural supply-side reform and the development of modern agricultural management.展开更多
Contrast Analysis (CA), Interlanguage(IL),cognitive approach are considered as three aspects closely related to Error Analysis (EA).Originated from CA, EA takes IL as its linguistic basis and cognitive approach as its...Contrast Analysis (CA), Interlanguage(IL),cognitive approach are considered as three aspects closely related to Error Analysis (EA).Originated from CA, EA takes IL as its linguistic basis and cognitive approach as its psychological support.Comparing with CA, EA pays more attention to the learner himself rather than the linguistic forms, and error is therefore shifted from what should be avoided to the crucial approach to the exploration of the learner’s cognitive process.展开更多
Nowadays the utilization of vegetable oils, particularly the palm oil, as fuel in the power plant, has made a significant development in the last few years. This vegetable oil can be used in particular in slow marine-...Nowadays the utilization of vegetable oils, particularly the palm oil, as fuel in the power plant, has made a significant development in the last few years. This vegetable oil can be used in particular in slow marine-derived diesel internal combustion engine (ICE), with an electric efficiency of about 40%. The efficiency is connected to the size of the power plant. Moreover, the considerable amount of the required vegetable oil to feed the system forces, especially in Italy, makes it necessary to import the fuel. This is the most critical element as the palm oil is subject to continuous variations in prices. Due to this variation it is difficult to stabilize a convenient fuel supply for a long period. The paper aims to evaluate and estimate the economic, technical and environmental feasibility of a 20 MW plant for the stationary power generation fed with palm oil, enlightening the system solution (technical constructive aspects) and the economic appraisal, on the basis of variations in oil prices. A comparison with a cogenerative power plant has been also carried out and, at last, the economic sensibility analysis based on the fuel cost and the European mechanisms of biomass incentives is performed.展开更多
The energy efficient product can be operated with longer duration.They offer wonderful solutions compared to other conventional water pumping system as it needs less maintenance,simple in installation,zero fuel cost,l...The energy efficient product can be operated with longer duration.They offer wonderful solutions compared to other conventional water pumping system as it needs less maintenance,simple in installation,zero fuel cost,longer operating life,highly reliable and free from production of greenhouse gases.In this paper we analyzed the different topologies of DC–DC converter in terms of their operating region of MPPT,quality of input and output currents.We discussed the MPPT algorithms to address partial shading effects in SPV array,present state of the technology,factors affecting the performance of the system,efficiency improvements and identified the research gaps.Also,the economic feasibility analysis has been done for the real time scenario using the Homer Pro software.The estimation of total dynamic head and horse power calculation has been done to decide the total load capacity.The economic analysis results such as cumulative cash flow over project lifetime of 25 years are presented.It is observed that the capital investment requirement is$7,425 for installing Fronius PV system that has a nominal capacity of 2.47 kW and annualized savings will be$134.93.In the long-term perspective,the return on investment is−2.18%as per the present tariff plan.展开更多
The microwave radiometer （MRM） onboard the Chang＇ E-1 （CE-I） lu- nar orbiter is a 4-frequency microwave radiometer, and it is mainly used to obtain the brightness temperature （TB） of the lunar surface, from whi...The microwave radiometer （MRM） onboard the Chang＇ E-1 （CE-I） lu- nar orbiter is a 4-frequency microwave radiometer, and it is mainly used to obtain the brightness temperature （TB） of the lunar surface, from which the thickness, temperature, dielectric constant and other related properties of the lunar regolith can be derived. The working mode of the CE-1 MRM, the ground calibration （including the official calibration coefficients）, as well as the acquisition and processing of the raw data are introduced. Our data analysis shows that TB increases with increasing frequency, decreases towards the lunar poles and is significantly affected by solar illumination. Our analysis also reveals that the main uncertainty in TB comes from ground calibration.展开更多
With the deepening of the reform of College English, the universities in our country have achieved some success, but there are still a lot of problems. The introduction of the flipped classroom teaching model provides...With the deepening of the reform of College English, the universities in our country have achieved some success, but there are still a lot of problems. The introduction of the flipped classroom teaching model provides a reliable way to improve the English teaching. As the center of the teaching activity, the flipped classroom can change students’ learning attitude change, which can improve the students’ learning autonomy, and effectively improve the students’ learning efficiency. In this paper, we introduce the concept of flipped classroom and its application in College English teaching practice, and we focus on the analysis of the flipped classroom teaching model and the feasibility of College English teaching.展开更多
One of the toughest challenges facing EFL/ESL instructors is that learners find it difficult to translate what they learn in grammar class into their own writing.Moreover,they make the same mistakes repeatedly after b...One of the toughest challenges facing EFL/ESL instructors is that learners find it difficult to translate what they learn in grammar class into their own writing.Moreover,they make the same mistakes repeatedly after being corrected.In order to improve students’writing,grammatical awareness is essential.Therefore,teachers should raise the students’level of awareness of syntactic patterns and transformations of the language(Koffi,2010).In this way,teachers are not merely giving the students answers directly,but are actually showing them how to solve these syntactic puzzles by themselves.The purpose of this paper is to analyze frequently made pronoun mistakes in College ESL students’writings to offer insights into how to use pronouns accurately and to enhance learners’writing skills.This paper will look closely at a set of writings done mostly by Somali ESL students in the hope of developing some pedagogical suggestions for teaching pronouns.Frequently made pronoun mistakes will be discussed with examples from students’writing samples.展开更多
Drying processing of Habanero chili was improved, through solar energy usage. Habanero chili is a notable seasonal product being drying such important for Mexican producers; this process is expensive and wasteful of e...Drying processing of Habanero chili was improved, through solar energy usage. Habanero chili is a notable seasonal product being drying such important for Mexican producers; this process is expensive and wasteful of energy. A feasibility analysis was developed, to determine the market tendency and the optimal drying conditions for redesign Habanero chili drying process, through a hybrid solar-electric energy usage. The new drying process would be held in two stages： （a） an open solar dryer was used; （b） an existing pilot fluidized bed dryer was adapted with a low temperature solar collector for air heating. Habanero chili was dehydrated from 90% to 5% moisture in 10.3 h, with good quality product, available for commercialization. A reduction in the average drying time of 50% was obtained, also, in the energy usage of 77% in the fluidized bed dryer, with an energy saving of 0.52 kg of natural gas per kg of fresh Habanero chili. An innovative sustainable efficient drying process was developed, and will be strategic to expand the market for Habanero chili with low energy cost.展开更多
The“one-stop”student community provides new support for innovation and entrepreneurship education in universities.Integrating innovation and entrepreneurship education into the“one-stop”student community work enri...The“one-stop”student community provides new support for innovation and entrepreneurship education in universities.Integrating innovation and entrepreneurship education into the“one-stop”student community work enriches course materials,integrates teacher resources,improves students’participation in innovation and entrepreneurship,and solves problems such as low student participation,lack of course resources,insufficient teacher resources,and single evaluation methods in traditional classrooms.Through various means such as exploring course resources,innovating management models,and strengthening team construction,the role of“one-stop”student communities in innovation and entrepreneurship education has been fully utilized,promoting the development of innovation and entrepreneurship education.展开更多
基金funded through Deanship of Scientific Research at Northern Border University,Arar,Saudi Arabia—project number“NBU-FFR-2025-3623-06”.
文摘Around the world,there has been a notable shift toward the use of renewable energy technology due to the growing demand for energy and the ongoing depletion of conventional resources,such as fossil fuels.Following this worldwide trend,Brunei’s government has initiated several strategic programs aimed at encouraging the establishment of energy from renewable sources in the nation’s energy mix.These initiatives are designed not only to support environmental sustainability but also to make energy from renewable sources increasingly competitive in comparison to more conventional energy sources like gas and oil,which have historically dominated Brunei’s energy market.The optimization of a hybrid energy system that combines diesel generators,solar photovoltaic(PV)panels,and the national power grid is the focus of this study.The objective is to identify the most cost-effective and environmentally sustainable configuration that can reliably meet local energy demands.During optimization,several configuration was tried and tested,including only grid,PV and Grid and PV-generator.HOMER(Hybrid Optimization of Multiple Energy Resources)software,a popular simulation tool that makes it possible to simulate and analyze hybrid energy systems,is utilized in the optimization process.Inside the HOMER Pro optimization,various system configuration is taken into account for the optimization.While simulating,it takes into account different combinations of components such as solar panels,wind turbines and batteries.Later on,it is being ranked by different factors such as net present cost(NPC),Cost of Energy(COE),etc.A comprehensive techno-economic research is carried out to evaluate various system configurations,considering key performance indicators such as total energy generation cost,operational expenditure,and greenhouse gas emissions.The results provide valuable insights into how renewable-based hybrid systems can reduce environmental impact while maintaining economic viability,supporting Brunei’s broader goals of energy diversification and sustainability.The study also emphasizes how such hybrid systems could be scaled for off-grid and rural populations in Brunei,where a dependable electricity supply is still a problem.Furthermore,sensitivity analyses were performed to evaluate the effects of variations in solar irradiation,load demand,and fuel prices on the overall system performance.Policymakers and energy planners can use these insights to help them make data-driven decisions about future investments in infrastructure for renewable energy.
基金Supported by Science and Technology Planning Project of Science Committee Science Committee(08DZ1980902)~~
文摘With the extending scale of agricultural production,the treatment and utilization of waste have become increasingly serious environmental problem.Taking city garden and Zhongnan pasture in Pujiang Town of Minhang District in Shanghai for example,according to the analysis on discharge characteristic of waste and balance of resources and energy utilization,mixed anaerobic digestion was chosen to dispose waste based on government guidance and feasibility analysis of project,and the combining disposal and resource utilization of waste were realized in two enterprises,providing reference for close cases.
文摘Objective:To assess the feasibility of coronary angiography by transradial approach with 4F catheter.Methods:The procedural details,picture quality,local complication were recorded for coronary by transradial approach with 4F catheter in 138 patients.Results:The success rate of angiography was 97.7%;fluoroscopy time was(5.05±3.23)minutes,total procedural time was(20.51±3.37)minutes;the incidence of dislodgement,excessive engagement of either coronary artery was 7.8%,9.4%,repectively;the angiographic scores for left anterior descending,circumflex and right coronary arteries were(2.87±0.40),(2.88±0.39),(2.90±0.35),respectively.The spasm complication occurred 4.3% in radial artery and 1.5% in coronary artery.There were no occlusion of radial artery during follow up.Conclusion:4F catheter could be the first chosen in some selecting patients for its nice maneuverability,fine images and fewer vascular complications.
基金National Natural Science Foundation of China(No.51275375,No.51509006)Shaanxi Provincial Natural Science Basic Research Plan(No.2014JQ7246)+1 种基金The Science and Technology of Hubei Province(No.B2015115)Doctoral Research Foundation of Hubei University of Automotive Technology(No.BK201403)
文摘In order to monitor the working state of piston motor and measure its instantaneous rotation speed accurately, the measuring principle and method of instantaneous rotation speed based on industrial personal computer and data acquisition card are introduced, and the major error source, influence mechanism and processing method of data quantization error are dis- cussed. By means of hybrid programming approach of LabVIEW and MATLAB, the instantaneous rotation speed measurement system for the piston motor in variable speed hydraulic system is designed. The simulation and experimental results show that the designed instantaneous speed measurement system is feasible. Furthermore, the sampling frequency has an important influ- ence on the instantaneous rotation speed measurement of piston motor and higher sampling frequency can lower quantization er- ror and improve measurement accuracy.
文摘Based on the decline in exploitation of coal resources, steep coal seam mining and mining face tensions continue to explore the feasibility analysis of steeply inclined faces in the gob. One of the key factors in utilizing the technology of gob-side entry retaining in steep coal seams is to safely and effectively prevent caving rock blocks from rushing into the gob-side entry by sliding downwards along levels. Using theoretical analysis and field methods, we numerically simulated the mining process on a fully-mechanized face in a steep coal seam. The stress and deformation process of roof strata has been analyzed, and the difficulty of utilizing the technology is considered and combined with practice in a steep working face in Lvshuidong mine. The feasibility of utilizing the technology of gob-side entry retaining in a steep coal seam has been recognised. We propose that roadways along the left lane offshoot body use a speciallymade reinforced steel dense net to build a dense rock face at the lower head. The results show that the lane offshoot branch creates effective roof control, safe conditions for roadway construction workers, and practical application of steeply inclined gob.
基金National Natural Science Foundation of China (No. 50475038).
文摘Laser tracking system （LTS） is an advanced device for large size 3D coordinates measuring with the advantages of broad range, high speed and high accuracy. However, its measuring accuracy is highly dominated by the geometric errors of the tracking mirror mechanism. Proper calibration of LTS is essential prior to the use of it for metrology. A kinematics model that describes not only the motion but also the geometric variations of LTS is developed. Through error analysis of the proposed model, it is claimed that gimbals axis misalignments and tracking mirror center off-set are the key contributors to measuring errors of LTS. A self-calibration method is presented of calibrating LTS with planar constraints. Various calibration strategies utilizing single-plane and multiple-plane constraints are proposed for different situations. For each calibration strategy, issues about the error parameter estimation of LTS are exploded to find out in which conditions these parameters can be uniquely estimated. Moreover, these conditions reveal the applicability of the planar constraints to LTS self-calibration. Intensive studies have been made to check validity of the theoretical results. The results show that the measuring accuracy of LTS has increased by 5 times since this technique for calibration is used.
基金supported by the National Natural Science Foundation of China(No.51635002 Key Program,52075016,U20A20281)。
文摘This paper presents a non-smooth multibody dynamic formulation and error analysis of an antenna pointing mechanism including frictional spatial revolute joints(FSRJs)with small clearance in the framework of the special Euclidian group SE(3).The formulation leads to an inertial frame-invariant,a compact and unified description for rigid bodies and spatial revolute joints(SRJs).The geometric constraint of the bearing is covered by four open semi-cylinders,which can be treated as bilateral constraints assuming that the impact effects are negligible.The frictional contact problem is formulated as a horizontal linear complementary problem(HLCP),which is embedded in the Lie-group integration scheme.Error of the antenna pointing mechanism is modeled by means of the adjoint transformation and POE-based formula.The evolution of errors is obtained through the solution of non-smooth dynamics.The obtained numerical results illustrate the influences of FSRJs in dynamics modeling and error analysis of the antenna pointing mechanism.
文摘Feasibility analysis of soft constraints for input and output variables is critical for model predictive control(MPC).When encountering the infeasible situation, some way should be found to adjust the constraints to guarantee that the optimal control law exists. For MPC integrated with soft sensor, considering the soft constraints for critical variables additionally makes it more complicated and difficult for feasibility analysis and constraint adjustment. Therefore, the main contributions are that a linear programming approach is proposed for feasibility analysis, and the corresponding constraint adjustment method and procedure are given as well. The feasibility analysis gives considerations to the manipulated, secondary and critical variables, and the increment of manipulated variables as well. The feasibility analysis and the constraint adjustment are conducted in the entire control process and guarantee the existence of optimal control. In final, a simulation case confirms the contributions in this paper.
文摘On Mauritania’s northern coast, wind and solar resources are abundant and must be used effectively. These resources have the potential to completely or partially replace the existing or projected diesel generators. The main objective of this case study is to study the possibility of using a hybrid system (HS) of the type (diesel, wind and storage). The most important part of this case study intended for this area will be to add the solar in a first phase and then the incorporation of an interconnection with the nearby network in a second phase. This interconnection will be secured by mean of medium voltage lines of 33 kV, where the nearest point is located 35 km away. Indeed, the study of the optimization model is carried out through Homer, which was developed by National Renewable Energy Laboratory [NREL]. Thus, it should be noted that the HS is analyzed on the basis of costs ($/kW) and price ($/kWh) and greenhouse gas emissions. Therefore, in order to achieve these techno-economic optimization objectives, this paper introduces a sensitivity analysis that has been proposed to determine the effect of costs on each HS configuration. In the end, HSs are needed for maximum use of renewable resources at the studied site for an uninterrupted power supply.
基金National Natural Science Foundation of China,No.41931293, No.41801175, No.42201287Postdoctoral Science Foundation of China,No.2020M680658。
文摘Cropping systems worldwide have been affected by the current trend in global warming and the optimization of cropping systems is an important area of research in the transition of agricultural land. The Loess Plateau is a typical ecologically fragile region with the most serious soil erosion in China. We carried out a field experiment in Yan’an city on the Loess Plateau to explore the effect of sowing date on crop growth and yield. We then analyzed the feasibility of a double-cropping system by considering climatic adaptability, ecological suitability and economic viability. Our results showed that different sowing dates resulted in significant differences in crop growth and that appropriate early sowing can result in higher crop yields for early maturing varieties. We showed that double-cropping systems of sweet maize(Zea mays)–forage rape and feed maize–forage rape are feasible on the Loess Plateau. We discuss the implications for the efficient use of farmland, which is important in guiding agricultural supply-side reform and the development of modern agricultural management.
文摘Contrast Analysis (CA), Interlanguage(IL),cognitive approach are considered as three aspects closely related to Error Analysis (EA).Originated from CA, EA takes IL as its linguistic basis and cognitive approach as its psychological support.Comparing with CA, EA pays more attention to the learner himself rather than the linguistic forms, and error is therefore shifted from what should be avoided to the crucial approach to the exploration of the learner’s cognitive process.
文摘Nowadays the utilization of vegetable oils, particularly the palm oil, as fuel in the power plant, has made a significant development in the last few years. This vegetable oil can be used in particular in slow marine-derived diesel internal combustion engine (ICE), with an electric efficiency of about 40%. The efficiency is connected to the size of the power plant. Moreover, the considerable amount of the required vegetable oil to feed the system forces, especially in Italy, makes it necessary to import the fuel. This is the most critical element as the palm oil is subject to continuous variations in prices. Due to this variation it is difficult to stabilize a convenient fuel supply for a long period. The paper aims to evaluate and estimate the economic, technical and environmental feasibility of a 20 MW plant for the stationary power generation fed with palm oil, enlightening the system solution (technical constructive aspects) and the economic appraisal, on the basis of variations in oil prices. A comparison with a cogenerative power plant has been also carried out and, at last, the economic sensibility analysis based on the fuel cost and the European mechanisms of biomass incentives is performed.
文摘The energy efficient product can be operated with longer duration.They offer wonderful solutions compared to other conventional water pumping system as it needs less maintenance,simple in installation,zero fuel cost,longer operating life,highly reliable and free from production of greenhouse gases.In this paper we analyzed the different topologies of DC–DC converter in terms of their operating region of MPPT,quality of input and output currents.We discussed the MPPT algorithms to address partial shading effects in SPV array,present state of the technology,factors affecting the performance of the system,efficiency improvements and identified the research gaps.Also,the economic feasibility analysis has been done for the real time scenario using the Homer Pro software.The estimation of total dynamic head and horse power calculation has been done to decide the total load capacity.The economic analysis results such as cumulative cash flow over project lifetime of 25 years are presented.It is observed that the capital investment requirement is$7,425 for installing Fronius PV system that has a nominal capacity of 2.47 kW and annualized savings will be$134.93.In the long-term perspective,the return on investment is−2.18%as per the present tariff plan.
基金supported by the National Natural Science Foundation of China (Grant No. 11173038)
文摘The microwave radiometer （MRM） onboard the Chang＇ E-1 （CE-I） lu- nar orbiter is a 4-frequency microwave radiometer, and it is mainly used to obtain the brightness temperature （TB） of the lunar surface, from which the thickness, temperature, dielectric constant and other related properties of the lunar regolith can be derived. The working mode of the CE-1 MRM, the ground calibration （including the official calibration coefficients）, as well as the acquisition and processing of the raw data are introduced. Our data analysis shows that TB increases with increasing frequency, decreases towards the lunar poles and is significantly affected by solar illumination. Our analysis also reveals that the main uncertainty in TB comes from ground calibration.
文摘With the deepening of the reform of College English, the universities in our country have achieved some success, but there are still a lot of problems. The introduction of the flipped classroom teaching model provides a reliable way to improve the English teaching. As the center of the teaching activity, the flipped classroom can change students’ learning attitude change, which can improve the students’ learning autonomy, and effectively improve the students’ learning efficiency. In this paper, we introduce the concept of flipped classroom and its application in College English teaching practice, and we focus on the analysis of the flipped classroom teaching model and the feasibility of College English teaching.
文摘One of the toughest challenges facing EFL/ESL instructors is that learners find it difficult to translate what they learn in grammar class into their own writing.Moreover,they make the same mistakes repeatedly after being corrected.In order to improve students’writing,grammatical awareness is essential.Therefore,teachers should raise the students’level of awareness of syntactic patterns and transformations of the language(Koffi,2010).In this way,teachers are not merely giving the students answers directly,but are actually showing them how to solve these syntactic puzzles by themselves.The purpose of this paper is to analyze frequently made pronoun mistakes in College ESL students’writings to offer insights into how to use pronouns accurately and to enhance learners’writing skills.This paper will look closely at a set of writings done mostly by Somali ESL students in the hope of developing some pedagogical suggestions for teaching pronouns.Frequently made pronoun mistakes will be discussed with examples from students’writing samples.
文摘Drying processing of Habanero chili was improved, through solar energy usage. Habanero chili is a notable seasonal product being drying such important for Mexican producers; this process is expensive and wasteful of energy. A feasibility analysis was developed, to determine the market tendency and the optimal drying conditions for redesign Habanero chili drying process, through a hybrid solar-electric energy usage. The new drying process would be held in two stages： （a） an open solar dryer was used; （b） an existing pilot fluidized bed dryer was adapted with a low temperature solar collector for air heating. Habanero chili was dehydrated from 90% to 5% moisture in 10.3 h, with good quality product, available for commercialization. A reduction in the average drying time of 50% was obtained, also, in the energy usage of 77% in the fluidized bed dryer, with an energy saving of 0.52 kg of natural gas per kg of fresh Habanero chili. An innovative sustainable efficient drying process was developed, and will be strategic to expand the market for Habanero chili with low energy cost.
基金Jiangsu Province Philosophy and Social Sciences General Project"Exploration of the Path for Cultivating Innovation and Entrepreneurship Ability of Employment-Oriented Applied Undergraduate Talents"。
文摘The“one-stop”student community provides new support for innovation and entrepreneurship education in universities.Integrating innovation and entrepreneurship education into the“one-stop”student community work enriches course materials,integrates teacher resources,improves students’participation in innovation and entrepreneurship,and solves problems such as low student participation,lack of course resources,insufficient teacher resources,and single evaluation methods in traditional classrooms.Through various means such as exploring course resources,innovating management models,and strengthening team construction,the role of“one-stop”student communities in innovation and entrepreneurship education has been fully utilized,promoting the development of innovation and entrepreneurship education.
