Scientific research on deep in situ resources is highly important to the theory and technology system construction for deep in-situ resource exploitation.To obtain high-condition preserved core samples,it is vital to ...Scientific research on deep in situ resources is highly important to the theory and technology system construction for deep in-situ resource exploitation.To obtain high-condition preserved core samples,it is vital to maintain the original material,humidity and luminous flux information inside the core.Therefore,this study proposes a research and development strategy for a high-toughness and highbarrier sealing film based on the molecular structure design and filler synergistic enhancement via a deep solid-state sealing film using in situ substance preservation(ISP),in situ moisture preservation(IMP)and in situ light preservation(ILP)coring principles.A graphene/epoxy composite sealing film with a high barrier,high strength and high toughness was developed.The oxygen permeability of the film was 0.23 cm^(3)/(m^(2)·d),the water vapor permeability was 1.26 g/(m^(2)·d),and the light transmittance was 0.The tensile strength reached 15.4 MPa,and the toughness was 5242.9 kJ/m^(3).The results from the film substance and moisture preservation performance verification experiments showed that the sealing film had an excellent sealing effect on small molecules,such as water,alkanes and even ions,which further verified that the sealing film greatly contributed to the maintenance and preservation of deep in-situ resource reserves and abundance.展开更多
Dear Editor,In this letter, a distributed self-consistent control method to coordinate low-carbon transportation and energy is proposed to address the efficient utilization of regional transportation energy and renewa...Dear Editor,In this letter, a distributed self-consistent control method to coordinate low-carbon transportation and energy is proposed to address the efficient utilization of regional transportation energy and renewable energy. Specifically, taking into account the coordinated development of transportation, power grids, and renewable energy, transportation energy self-consistent, including instant self-consistent rate and power self-consistent rate。展开更多
Purpose-It is quite universal for high-speed turnouts to be exposed to the wear of the stock rail of the switch rail during the service process.The wear will cause the change of railhead profile and the relative posit...Purpose-It is quite universal for high-speed turnouts to be exposed to the wear of the stock rail of the switch rail during the service process.The wear will cause the change of railhead profile and the relative positions of the switch rail and the stock rail,which will directly affect the wheel-rail contact state and wheel load transition when a train passes the turnout and will further impose serious impacts on the safety and stability of train operation.The purpose of this paper is to provide suggestions for wear management of high-speed turnout.Design/methodology/approach-The actual wear characteristics of switch rails of high-speed turnouts in different guiding directions were studied based on the monitoring results on site;the authorized wear limits for the switch rails of high-speed turnout were studied through derailment risk analysis and switch rail strength analysis.Findings-The results show that:the major factor for the service life of a curved switch rail is the lateral wear.The wear characteristics of the curved switch rail of a facing turnout are significantly different from those of a trailing turnout.To be specific,the lateral wear of the curved switch rail mainly occurs in the narrower section at its front end for a trailing turnout,but in the wider section at its rear end when for a facing turnout.The maximum lateral wear of a dismounted switch rail from a trailing turnout is found on the 15-mm wide section and is 3.9 mm,which does not reach the specified limit of 6 mm.For comparison,the lateral wear of a dismounted switch rail from a facing turnout is found from the 35-mm wide section to the full-width section and is greater than 7.5 mm,which exceeds the specified limit.Based on this,in addition to meeting the requirements of maintenance rules,the allowed wear of switch rails of high-speed turnout shall be so that the dangerous area with a tangent angle of wheel profile smaller than 43.68 will not contact the switch rail when the wheel is lifted by 2 mm.Accordingly,the lateral wear limit at the 5-mm wide section of the curved switch rail shall be reduced from 6 mm(as specified)to 3.5 mm.Originality/value-The work in this paper is of reference significance to the research on the development law of rail wear in high-speed turnout area and the formulation of relevant standards.展开更多
Since the efficiency of photovoltaic(PV) power is closely related to the weather,many PV enterprises install weather instruments to monitor the working state of the PV power system.With the development of the soft mea...Since the efficiency of photovoltaic(PV) power is closely related to the weather,many PV enterprises install weather instruments to monitor the working state of the PV power system.With the development of the soft measurement technology,the instrumental method seems obsolete and involves high cost.This paper proposes a novel method for predicting the types of weather based on the PV power data and partial meteorological data.By this method,the weather types are deduced by data analysis,instead of weather instrument A better fault detection is obtained by using the support vector machines(SVM) and comparing the predicted and the actual weather.The model of the weather prediction is established by a direct SVM for training multiclass predictors.Although SVM is suitable for classification,the classified results depend on the type of the kernel,the parameters of the kernel,and the soft margin coefficient,which are difficult to choose.In this paper,these parameters are optimized by particle swarm optimization(PSO) algorithm in anticipation of good prediction results can be achieved.Prediction results show that this method is feasible and effective.展开更多
By constructing a new conformal mapping function, we study the surface effects on six edge nano-cracks emanating from a regular hexagonal nano-hole in one-dimensional (1D) hexagonal piezoelectric quasicrystals under a...By constructing a new conformal mapping function, we study the surface effects on six edge nano-cracks emanating from a regular hexagonal nano-hole in one-dimensional (1D) hexagonal piezoelectric quasicrystals under anti-plane shear. Based on the Gurtin–Murdoch surface/interface model and complex potential theory, the exact solutions of phonon field, phason field and electric field are obtained. The analytical solutions of the stress intensity factor of the phonon field, the stress intensity factor of the phason field, the electric displacement intensity factor and the energy release rate are given. The interaction effects of the nano-cracks and nano-hole on the stress intensity factor of the phonon field, the stress intensity factor of the phason field and the electric displacement intensity factor are discussed in numerical examples. It can be seen that the surface effect leads to the coupling of phonon field, phason field and electric field. With the decrease of cavity size, the influence of surface effect is more obvious.展开更多
As water scarcity is becoming a growing threat to human development, finding effective solutions has become an urgent need. To make better use of water resources, seawater desalination and storage systems using renewa...As water scarcity is becoming a growing threat to human development, finding effective solutions has become an urgent need. To make better use of water resources, seawater desalination and storage systems using renewable energy sources(RES) are designed and implemented around the world. In this paper, an optimal capacity planning method for RES-pumped storage-seawater desalination(RES-PS-D) system is introduced. The configuration of the RES-PS-D system is clarified first, after which a cost-benefit analysis is performed using all cost and benefit components. A function for determining maximum economic benefits of the RES-PS-D system is then established, and the constraints are proposed based on various limitations. The mixed-integer linear programming algorithm is applied to solve the optimal function. A case study is introduced to validate the feasibility and effectiveness of the method. The conclusion shows that the strategy is suitable for solving the configuration optimization problem, and finally both merits and defects of the method are discussed.展开更多
CO_(2)mineralization as a promising CO_(2)mitigation strategy can employ industrial alkaline solid wastes to achieve net emission reduction of atmospheric CO_(2).The red mud is a strong alkalinity waste residue produc...CO_(2)mineralization as a promising CO_(2)mitigation strategy can employ industrial alkaline solid wastes to achieve net emission reduction of atmospheric CO_(2).The red mud is a strong alkalinity waste residue produced from the aluminum industry by the Bayer process which has the potential for the industrial CO_(2)large scale treatment.However,limited by complex components of red mud and harsh operating conditions,it is challenging to directly mineralize CO_(2)using red mud to recover carbon and sodium resources and to produce mineralized products simultaneously with high economic value efficiently.Herein,we propose a novel electrochemical CO_(2)mineralization strategy for red mud treatment driven by hydrogen-cycled membrane electrolysis,realizing mineralization of CO_(2)efficiently and recovery of carbon and sodium resources with economic value.The system utilizes H_(2)as the redox-active proton carrier to drive the cathode and anode to generate OH^(-) and H^(+) at low voltage,respectively.The H^(+) plays as a neutralizer for the alkalinity of red mud and the OH^(-) is used to mineralize CO_(2)into generate highpurity NaHCO_(3)product.We verify that the system can effectively recover carbon and sodium resources in red mud treatment process,which shows that the average electrolysis efficiency is 95.3%with highpurity(99.4%)NaHCO_(3)product obtained.The low electrolysis voltage of 0.453 V is achieved at10 mA·cm^(-2) in this system indicates a potential low energy consumption industrial process.Further,we successfully demonstrate that this process has the ability of direct efficient mineralization of flue gas CO_(2)(15%volume)without extra capturing,being a novel potential strategy for carbon neutralization.展开更多
For a single machine infinite power system with thyristor controlled series compensation(TCSC) device, which is affected by system model uncertainties, nonlinear time-delays and external unknown disturbances, we prese...For a single machine infinite power system with thyristor controlled series compensation(TCSC) device, which is affected by system model uncertainties, nonlinear time-delays and external unknown disturbances, we present a robust adaptive backstepping control scheme based on the radial basis function neural network(RBFNN). The RBFNN is introduced to approximate the complex nonlinear function involving uncertainties and external unknown disturbances, and meanwhile a new robust term is constructed to further estimate the system residual error,which removes the requirement of knowing the upper bound of the disturbances and uncertainty terms. The stability analysis of the power system is presented based on the Lyapunov function,which can guarantee the uniform ultimate boundedness(UUB) of all parameters and states of the whole closed-loop system. A comparison is made between the RBFNN-based robust adaptive control and the general backstepping control in the simulation part to verify the effectiveness of the proposed control scheme.展开更多
For plant-wide processes with multiple operating conditions,the multimode feature imposes some challenges to conventional monitoring techniques.Hence,to solve this problem,this paper provides a novel local component b...For plant-wide processes with multiple operating conditions,the multimode feature imposes some challenges to conventional monitoring techniques.Hence,to solve this problem,this paper provides a novel local component based principal component analysis(LCPCA)approach for monitoring the status of a multimode process.In LCPCA,the process prior knowledge of mode division is not required and it purely based on the process data.Firstly,LCPCA divides the processes data into multiple local components using finite Gaussian mixture model mixture(FGMM).Then,calculating the posterior probability is applied to determine each sample belonging to which local component.After that,the local component information(such as mean and standard deviation)is used to standardize each sample of local component.Finally,the standardized samples of each local component are combined to train PCA monitoring model.Based on the PCA monitoring model,two monitoring statistics T^(2) and SPE are used for monitoring multimode processes.Through a numerical example and the Tennessee Eastman(TE)process,the monitoring result demonstrates that LCPCA outperformed conventional PCA and LNS-PCA in the fault detection rate.展开更多
This paper focuses on the optimal scheduling of the district energy system with multiple energy supply modes and flexible loads.For multi-energy system(MES),the energy hub(EH)model including energy storage system and ...This paper focuses on the optimal scheduling of the district energy system with multiple energy supply modes and flexible loads.For multi-energy system(MES),the energy hub(EH)model including energy storage system and integrated electric vehicle(EV)is established.Based on the model,the influence of pollutant trading market on total operation cost is analyzed,and the optimal scheduling strategy is further put forward to realize the minimum purchase cost and emission tax cost of the MES.Finally,this paper compares the economic benefit of the fixed mode and the response mode,and discusses the contribution of the energy storage device and the multi-energy complementary mode to energy utilization efficiency.The simulation results indicate that optimal scheduling strategy of the EH can coordinate various energy complementary modes reasonably.Meanwhile,the proposed strategy is able to improve the operation economy of the EH,and ensure the better response effect of the demand side.The sensitivity analysis demonstrates the impact of pollutant emission price change on emission reduction.展开更多
With the gradual increase of distributed energy penetration,the traditional optimization model of distribution network can no longer guarantee the stable and efficient operation of the distribution network.In order to...With the gradual increase of distributed energy penetration,the traditional optimization model of distribution network can no longer guarantee the stable and efficient operation of the distribution network.In order to deal with the inevitable uncertainty of distributed energy,a new robust optimal operation method is proposed for active distribution network(ADN)based on the minimum confidence interval of distributed energy Beta distribution in this paper.First,an ADN model is established with second-order cone to include the energy storage device,capacitor bank,static var compensator,on-load tap changer,wind turbine and photovoltaic.Then,the historical data of related distributed energy are analyzed and described by the probability density function,and the minimum confidence interval is obtained by interval searching.Furthermore,via taking this minimum confidence interval as the uncertain interval,a less conservative two-stage robust optimization model is established and solved for ADN.The simulation results for the IEEE33-bus distribution network have verified that the proposed method can realize a more stable and efficient operation of the distribution network compared with the traditional robust optimization method.展开更多
Ignoring load characteristics and not considering user feeling with regard to the optimal operation of Energy Internet(EI) results in a large error in optimization. Thus, results are not consistent with the actual ope...Ignoring load characteristics and not considering user feeling with regard to the optimal operation of Energy Internet(EI) results in a large error in optimization. Thus, results are not consistent with the actual operating conditions. To solve these problems, this paper proposes an optimization method based on user Electricity Anxiety(EA) and Chaotic Space Variation Particle Swarm Optimization(CSVPSO). First, the load is divided into critical load, translation load, shiftable load, and temperature load. Then, on the basis of the different load characteristics,the concept of the user EA degree is presented, and the optimization model of the EI is provided. This paper also presents a CSVPSO algorithm to solve the optimization problem because the traditional particle swarm optimization algorithm takes a long time and particles easily fall into the local optimum. In CSVPSO, the particles with lower fitness value are operated by using cross operation, and velocity variation is performed for particles with a speed lower than the setting threshold. The effectiveness of the proposed method is verified by simulation analysis.Simulation results show that the proposed method can be used to optimize the operation of EI on the basis of the full consideration of the load characteristics. Moreover, the optimization algorithm has high accuracy and computational efficiency.展开更多
Standing on the potential for high-speed modulation and switching in the terahertz (THz) regime, all-optical approaches whose response speeds mainly depend on the lifetime of nonequilibrium free carriers have attracte...Standing on the potential for high-speed modulation and switching in the terahertz (THz) regime, all-optical approaches whose response speeds mainly depend on the lifetime of nonequilibrium free carriers have attracted a tremendous attention. Here, we establish a novel bi-direction THz modulation experiment controlled by femtosecond laser for new functional devices. Specifically, time-resolved transmission measurements are conducted on a series of thin layers Bi2Se3 films fabricated straightforwardly on AI2O3 substrates, with the pump fluence range from 25(iJ/cm2 to 200 |iJ/cm2 per pulse. After photoexcitation, an ultrafast switching of THz wave with a full recovery time of ?1 Ops is observed. For a longer timescale, a photoinduced increase in the transmitted THz amplitude is found in the 8 and 10 quintuple layers (QL) BizSR, which shows a thickness-dependent topological phase transition. Additionally, the broadband modulation effect of the 8 QL Bi2Se3 film is presented at the time delays of 2.2ps and 12.5ps which have a maximum modulation depth of 6.4% and 1.3% under the pump fluence of 200(iJ/cm2, respectively. Furthermore, the absorption of a optical phonon at 1.9 THz shows a time-dependent evolution which is consistent with the cooling of lattice temperature.展开更多
The efficient heat dissipation of electronic equipment is very important,its heat dissipation performance directly determines the life of the equipment itself.A hand-held electronic communications equipment,when used ...The efficient heat dissipation of electronic equipment is very important,its heat dissipation performance directly determines the life of the equipment itself.A hand-held electronic communications equipment,when used in surface temperature is exorbitant,need to heat dissipation equipment efficiently,to ensure that the use of comfort in the handheld.In accordance with this requirement,this article presents a flexible composite material based on nano-efficient cooling methods that can keep the layout,through the improvement of internal thermal path,it can achieve the effective heat dissipation.The network thermal resistance method is used to analyze the heat transfer in the equipment,and the thermal analysis of the local thermal resistance is carried out.At the same time,through the modeling of electronic equipment and the analysis of finite elements,the temperature drop of the equipment after improvement is accurately judged.Finally,the device experimental performance comparison before and after the optimization of the standby mode and working mode is verified.The results show that the optimized equipment heat source temperature can be reduced by up to 8.5℃,the surface temperature of the equipment can be reduced by about 5℃~7℃,and the final control equipment in the steady standby state of the temperature of about 39±0.5℃,to ensure the comfort of use,and also improved the service life of the equipment.The efficient thermal design of electronic equipment based on flexible nanocomposites can provide a convenient and reliable cooling solution for high-heat flow density devices.展开更多
基金supported by the Program for National Natural Science Foundation of China(Nos.52004166,51827901 and U2013603)Guangdong Introducing Innovative and Enterpreneurial Teams(No.2019ZT08G315).
文摘Scientific research on deep in situ resources is highly important to the theory and technology system construction for deep in-situ resource exploitation.To obtain high-condition preserved core samples,it is vital to maintain the original material,humidity and luminous flux information inside the core.Therefore,this study proposes a research and development strategy for a high-toughness and highbarrier sealing film based on the molecular structure design and filler synergistic enhancement via a deep solid-state sealing film using in situ substance preservation(ISP),in situ moisture preservation(IMP)and in situ light preservation(ILP)coring principles.A graphene/epoxy composite sealing film with a high barrier,high strength and high toughness was developed.The oxygen permeability of the film was 0.23 cm^(3)/(m^(2)·d),the water vapor permeability was 1.26 g/(m^(2)·d),and the light transmittance was 0.The tensile strength reached 15.4 MPa,and the toughness was 5242.9 kJ/m^(3).The results from the film substance and moisture preservation performance verification experiments showed that the sealing film had an excellent sealing effect on small molecules,such as water,alkanes and even ions,which further verified that the sealing film greatly contributed to the maintenance and preservation of deep in-situ resource reserves and abundance.
基金supported by the National Natural Science Foundation of China(U1908217,61703081)。
文摘Dear Editor,In this letter, a distributed self-consistent control method to coordinate low-carbon transportation and energy is proposed to address the efficient utilization of regional transportation energy and renewable energy. Specifically, taking into account the coordinated development of transportation, power grids, and renewable energy, transportation energy self-consistent, including instant self-consistent rate and power self-consistent rate。
基金supported by the Fund of China Academy of Railway Sciences Corporation Limited (Grant Nos.2022YJ177 and 2022YJ088).
文摘Purpose-It is quite universal for high-speed turnouts to be exposed to the wear of the stock rail of the switch rail during the service process.The wear will cause the change of railhead profile and the relative positions of the switch rail and the stock rail,which will directly affect the wheel-rail contact state and wheel load transition when a train passes the turnout and will further impose serious impacts on the safety and stability of train operation.The purpose of this paper is to provide suggestions for wear management of high-speed turnout.Design/methodology/approach-The actual wear characteristics of switch rails of high-speed turnouts in different guiding directions were studied based on the monitoring results on site;the authorized wear limits for the switch rails of high-speed turnout were studied through derailment risk analysis and switch rail strength analysis.Findings-The results show that:the major factor for the service life of a curved switch rail is the lateral wear.The wear characteristics of the curved switch rail of a facing turnout are significantly different from those of a trailing turnout.To be specific,the lateral wear of the curved switch rail mainly occurs in the narrower section at its front end for a trailing turnout,but in the wider section at its rear end when for a facing turnout.The maximum lateral wear of a dismounted switch rail from a trailing turnout is found on the 15-mm wide section and is 3.9 mm,which does not reach the specified limit of 6 mm.For comparison,the lateral wear of a dismounted switch rail from a facing turnout is found from the 35-mm wide section to the full-width section and is greater than 7.5 mm,which exceeds the specified limit.Based on this,in addition to meeting the requirements of maintenance rules,the allowed wear of switch rails of high-speed turnout shall be so that the dangerous area with a tangent angle of wheel profile smaller than 43.68 will not contact the switch rail when the wheel is lifted by 2 mm.Accordingly,the lateral wear limit at the 5-mm wide section of the curved switch rail shall be reduced from 6 mm(as specified)to 3.5 mm.Originality/value-The work in this paper is of reference significance to the research on the development law of rail wear in high-speed turnout area and the formulation of relevant standards.
基金supported by the National Natural Science Foundation of China(61433004,61473069)IAPI Fundamental Research Funds(2013ZCX14)+1 种基金supported by the Development Project of Key Laboratory of Liaoning Provincethe Enterprise Postdoctoral Fund Projects of Liaoning Province
文摘Since the efficiency of photovoltaic(PV) power is closely related to the weather,many PV enterprises install weather instruments to monitor the working state of the PV power system.With the development of the soft measurement technology,the instrumental method seems obsolete and involves high cost.This paper proposes a novel method for predicting the types of weather based on the PV power data and partial meteorological data.By this method,the weather types are deduced by data analysis,instead of weather instrument A better fault detection is obtained by using the support vector machines(SVM) and comparing the predicted and the actual weather.The model of the weather prediction is established by a direct SVM for training multiclass predictors.Although SVM is suitable for classification,the classified results depend on the type of the kernel,the parameters of the kernel,and the soft margin coefficient,which are difficult to choose.In this paper,these parameters are optimized by particle swarm optimization(PSO) algorithm in anticipation of good prediction results can be achieved.Prediction results show that this method is feasible and effective.
基金Project supported by the National Key R&D Program of China (Grant No. 2017YFC1405605)the Innovation Youth Fund of the Ocean Telemetry Technology Innovation Center of the Ministry of Natural Resources, China (Grant No. 21k20190088)+1 种基金the Natural Science Foundation of Inner Mongolia, China (Grant No. 2018MS01005)the Graduate Students' Scientific Research Innovation Program of Inner Mongolia Normal University (Grant No. CXJJS19098).
文摘By constructing a new conformal mapping function, we study the surface effects on six edge nano-cracks emanating from a regular hexagonal nano-hole in one-dimensional (1D) hexagonal piezoelectric quasicrystals under anti-plane shear. Based on the Gurtin–Murdoch surface/interface model and complex potential theory, the exact solutions of phonon field, phason field and electric field are obtained. The analytical solutions of the stress intensity factor of the phonon field, the stress intensity factor of the phason field, the electric displacement intensity factor and the energy release rate are given. The interaction effects of the nano-cracks and nano-hole on the stress intensity factor of the phonon field, the stress intensity factor of the phason field and the electric displacement intensity factor are discussed in numerical examples. It can be seen that the surface effect leads to the coupling of phonon field, phason field and electric field. With the decrease of cavity size, the influence of surface effect is more obvious.
基金supported by the National Natural Science Foundation of China (No.61703081)the Natural Science Foundation of Liaoning Province (No.20170520113)the State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources (No.LAPS19005)
文摘As water scarcity is becoming a growing threat to human development, finding effective solutions has become an urgent need. To make better use of water resources, seawater desalination and storage systems using renewable energy sources(RES) are designed and implemented around the world. In this paper, an optimal capacity planning method for RES-pumped storage-seawater desalination(RES-PS-D) system is introduced. The configuration of the RES-PS-D system is clarified first, after which a cost-benefit analysis is performed using all cost and benefit components. A function for determining maximum economic benefits of the RES-PS-D system is then established, and the constraints are proposed based on various limitations. The mixed-integer linear programming algorithm is applied to solve the optimal function. A case study is introduced to validate the feasibility and effectiveness of the method. The conclusion shows that the strategy is suitable for solving the configuration optimization problem, and finally both merits and defects of the method are discussed.
基金funded by the Science and Technology Department of Sichuan Province(2020YFH0012)。
文摘CO_(2)mineralization as a promising CO_(2)mitigation strategy can employ industrial alkaline solid wastes to achieve net emission reduction of atmospheric CO_(2).The red mud is a strong alkalinity waste residue produced from the aluminum industry by the Bayer process which has the potential for the industrial CO_(2)large scale treatment.However,limited by complex components of red mud and harsh operating conditions,it is challenging to directly mineralize CO_(2)using red mud to recover carbon and sodium resources and to produce mineralized products simultaneously with high economic value efficiently.Herein,we propose a novel electrochemical CO_(2)mineralization strategy for red mud treatment driven by hydrogen-cycled membrane electrolysis,realizing mineralization of CO_(2)efficiently and recovery of carbon and sodium resources with economic value.The system utilizes H_(2)as the redox-active proton carrier to drive the cathode and anode to generate OH^(-) and H^(+) at low voltage,respectively.The H^(+) plays as a neutralizer for the alkalinity of red mud and the OH^(-) is used to mineralize CO_(2)into generate highpurity NaHCO_(3)product.We verify that the system can effectively recover carbon and sodium resources in red mud treatment process,which shows that the average electrolysis efficiency is 95.3%with highpurity(99.4%)NaHCO_(3)product obtained.The low electrolysis voltage of 0.453 V is achieved at10 mA·cm^(-2) in this system indicates a potential low energy consumption industrial process.Further,we successfully demonstrate that this process has the ability of direct efficient mineralization of flue gas CO_(2)(15%volume)without extra capturing,being a novel potential strategy for carbon neutralization.
基金supported in part by the National Natural Science Foundation of China(61433004,61703289)
文摘For a single machine infinite power system with thyristor controlled series compensation(TCSC) device, which is affected by system model uncertainties, nonlinear time-delays and external unknown disturbances, we present a robust adaptive backstepping control scheme based on the radial basis function neural network(RBFNN). The RBFNN is introduced to approximate the complex nonlinear function involving uncertainties and external unknown disturbances, and meanwhile a new robust term is constructed to further estimate the system residual error,which removes the requirement of knowing the upper bound of the disturbances and uncertainty terms. The stability analysis of the power system is presented based on the Lyapunov function,which can guarantee the uniform ultimate boundedness(UUB) of all parameters and states of the whole closed-loop system. A comparison is made between the RBFNN-based robust adaptive control and the general backstepping control in the simulation part to verify the effectiveness of the proposed control scheme.
基金National Natural Science Foundation of China(61673279)。
文摘For plant-wide processes with multiple operating conditions,the multimode feature imposes some challenges to conventional monitoring techniques.Hence,to solve this problem,this paper provides a novel local component based principal component analysis(LCPCA)approach for monitoring the status of a multimode process.In LCPCA,the process prior knowledge of mode division is not required and it purely based on the process data.Firstly,LCPCA divides the processes data into multiple local components using finite Gaussian mixture model mixture(FGMM).Then,calculating the posterior probability is applied to determine each sample belonging to which local component.After that,the local component information(such as mean and standard deviation)is used to standardize each sample of local component.Finally,the standardized samples of each local component are combined to train PCA monitoring model.Based on the PCA monitoring model,two monitoring statistics T^(2) and SPE are used for monitoring multimode processes.Through a numerical example and the Tennessee Eastman(TE)process,the monitoring result demonstrates that LCPCA outperformed conventional PCA and LNS-PCA in the fault detection rate.
基金Carry out quality evaluation research of generic medicinal product control based on domestic product,NMPA Key Laboratory for Quality Research and Evaluation of Chemical Drugs,Beijing,China。
基金supported in part by the National Natural Science Foundation of China(No.61433004,No.61703289)。
文摘This paper focuses on the optimal scheduling of the district energy system with multiple energy supply modes and flexible loads.For multi-energy system(MES),the energy hub(EH)model including energy storage system and integrated electric vehicle(EV)is established.Based on the model,the influence of pollutant trading market on total operation cost is analyzed,and the optimal scheduling strategy is further put forward to realize the minimum purchase cost and emission tax cost of the MES.Finally,this paper compares the economic benefit of the fixed mode and the response mode,and discusses the contribution of the energy storage device and the multi-energy complementary mode to energy utilization efficiency.The simulation results indicate that optimal scheduling strategy of the EH can coordinate various energy complementary modes reasonably.Meanwhile,the proposed strategy is able to improve the operation economy of the EH,and ensure the better response effect of the demand side.The sensitivity analysis demonstrates the impact of pollutant emission price change on emission reduction.
基金Carry out quality evaluation research of generic medicinal product control based on domestic product,NMPA Key Laboratory for Quality Research and Evaluation of Chemical Drugs,Beijing,China。
基金supported in part by the National Natural Science Foundation of China(No.61703081)the Liaoning Joint Fund of National Natural Science Foundation of China(No.U1908217)+1 种基金the Natural Science Foundation of Liaoning Province(No.20170520113)the Fundamental Research Funds for the Central Universities(No.N2004016)。
文摘With the gradual increase of distributed energy penetration,the traditional optimization model of distribution network can no longer guarantee the stable and efficient operation of the distribution network.In order to deal with the inevitable uncertainty of distributed energy,a new robust optimal operation method is proposed for active distribution network(ADN)based on the minimum confidence interval of distributed energy Beta distribution in this paper.First,an ADN model is established with second-order cone to include the energy storage device,capacitor bank,static var compensator,on-load tap changer,wind turbine and photovoltaic.Then,the historical data of related distributed energy are analyzed and described by the probability density function,and the minimum confidence interval is obtained by interval searching.Furthermore,via taking this minimum confidence interval as the uncertain interval,a less conservative two-stage robust optimization model is established and solved for ADN.The simulation results for the IEEE33-bus distribution network have verified that the proposed method can realize a more stable and efficient operation of the distribution network compared with the traditional robust optimization method.
文摘Ignoring load characteristics and not considering user feeling with regard to the optimal operation of Energy Internet(EI) results in a large error in optimization. Thus, results are not consistent with the actual operating conditions. To solve these problems, this paper proposes an optimization method based on user Electricity Anxiety(EA) and Chaotic Space Variation Particle Swarm Optimization(CSVPSO). First, the load is divided into critical load, translation load, shiftable load, and temperature load. Then, on the basis of the different load characteristics,the concept of the user EA degree is presented, and the optimization model of the EI is provided. This paper also presents a CSVPSO algorithm to solve the optimization problem because the traditional particle swarm optimization algorithm takes a long time and particles easily fall into the local optimum. In CSVPSO, the particles with lower fitness value are operated by using cross operation, and velocity variation is performed for particles with a speed lower than the setting threshold. The effectiveness of the proposed method is verified by simulation analysis.Simulation results show that the proposed method can be used to optimize the operation of EI on the basis of the full consideration of the load characteristics. Moreover, the optimization algorithm has high accuracy and computational efficiency.
文摘Standing on the potential for high-speed modulation and switching in the terahertz (THz) regime, all-optical approaches whose response speeds mainly depend on the lifetime of nonequilibrium free carriers have attracted a tremendous attention. Here, we establish a novel bi-direction THz modulation experiment controlled by femtosecond laser for new functional devices. Specifically, time-resolved transmission measurements are conducted on a series of thin layers Bi2Se3 films fabricated straightforwardly on AI2O3 substrates, with the pump fluence range from 25(iJ/cm2 to 200 |iJ/cm2 per pulse. After photoexcitation, an ultrafast switching of THz wave with a full recovery time of ?1 Ops is observed. For a longer timescale, a photoinduced increase in the transmitted THz amplitude is found in the 8 and 10 quintuple layers (QL) BizSR, which shows a thickness-dependent topological phase transition. Additionally, the broadband modulation effect of the 8 QL Bi2Se3 film is presented at the time delays of 2.2ps and 12.5ps which have a maximum modulation depth of 6.4% and 1.3% under the pump fluence of 200(iJ/cm2, respectively. Furthermore, the absorption of a optical phonon at 1.9 THz shows a time-dependent evolution which is consistent with the cooling of lattice temperature.
基金This work was funded by the Manned spaceflight project in advance(020301).
文摘The efficient heat dissipation of electronic equipment is very important,its heat dissipation performance directly determines the life of the equipment itself.A hand-held electronic communications equipment,when used in surface temperature is exorbitant,need to heat dissipation equipment efficiently,to ensure that the use of comfort in the handheld.In accordance with this requirement,this article presents a flexible composite material based on nano-efficient cooling methods that can keep the layout,through the improvement of internal thermal path,it can achieve the effective heat dissipation.The network thermal resistance method is used to analyze the heat transfer in the equipment,and the thermal analysis of the local thermal resistance is carried out.At the same time,through the modeling of electronic equipment and the analysis of finite elements,the temperature drop of the equipment after improvement is accurately judged.Finally,the device experimental performance comparison before and after the optimization of the standby mode and working mode is verified.The results show that the optimized equipment heat source temperature can be reduced by up to 8.5℃,the surface temperature of the equipment can be reduced by about 5℃~7℃,and the final control equipment in the steady standby state of the temperature of about 39±0.5℃,to ensure the comfort of use,and also improved the service life of the equipment.The efficient thermal design of electronic equipment based on flexible nanocomposites can provide a convenient and reliable cooling solution for high-heat flow density devices.
