In this paper,we study the optimal investment problem of an insurer whose surplus process follows the diffusion approximation of the classical Cramer-Lundberg model.Investment in the foreign markets is allowed,and the...In this paper,we study the optimal investment problem of an insurer whose surplus process follows the diffusion approximation of the classical Cramer-Lundberg model.Investment in the foreign markets is allowed,and therefore,the foreign exchange rate model is incorporated.Under the allowing of selling and borrowing,the problem of maximizing the expected exponential utility of terminal wealth is studied.By solving the corresponding Hamilton-Jacobi-Bellman equations,the optimal investment strategies and value functions are obtained.Finally,numerical analysis is presented.展开更多
High-quality antiferromagnetic(AFM)θ-phase manganese nitride(MnN)films were successfully grown on MgO(001)substrates by plasma-assisted molecular beam epitaxy.Structural analysis confirms the high-quality MnN film ha...High-quality antiferromagnetic(AFM)θ-phase manganese nitride(MnN)films were successfully grown on MgO(001)substrates by plasma-assisted molecular beam epitaxy.Structural analysis confirms the high-quality MnN film has a tetragonal distortion with a c/a ratio of~0.98.The film exhibits exceptional stability in both aqueous and ambient conditions,which is a crucial factor for practical applications.Electrical transport reveals its metallic behavior with an upturn at low temperatures,which could be attributed to the Kondo effect originated from nitrogen vacancy-induced magnetic impurities.Room temperature exchange bias has been demonstrated in a MnN/CoFeB heterostructure,verifying the AFM ordering of MnN.Considering its high Néel temperature~650 K,superior stability,and low-cost,this work highlights the epitaxial MnN films as a promising candidate for AFM spintronic applications.展开更多
The weak adsorption energy of oxygen-containing intermediates on Co center leads to a considerable performance dis-parity between Co-N-C and costly Pt benchmark in catalyzing oxygen reduction reaction(ORR).In this wor...The weak adsorption energy of oxygen-containing intermediates on Co center leads to a considerable performance dis-parity between Co-N-C and costly Pt benchmark in catalyzing oxygen reduction reaction(ORR).In this work,we strategi-cally engineer the active site structure of Co-N-C via B substitution,which is accomplished by the pyrolysis of ammonium borate.During this process,the in-situ generated NH_(3)gas plays a critical role in creating surface defects and boron atoms substituting nitrogen atoms in the carbon structure.The well-designed CoB_(1)N_(3)active site endows Co with higher charge density and stronger adsorption energy toward oxygen species,potentially accelerating ORR kinetics.As expected,the resulting Co-B/N-C catalyst exhibited superior ORR performance over Co-N-C counterpart,with 40 mV,and fivefold en-hancement in half-wave potential and turnover frequency(TOF).More importantly,the excellent ORR performance could be translated into membrane electrode assembly(MEA)in a fuel cell test,delivering an impressive peak power density of 824 mW·cm^(-2),which is currently the best among Co-based catalysts under the same conditions.This work not only demon-strates an effective method for designing advanced catalysts,but also affords a highly promising non-precious metal ORR electrocatalyst for fuel cell applications.展开更多
In this paper,a fusion model based on a long short-term memory(LSTM)neural network and enhanced search ant colony optimization(ENSACO)is proposed to predict the power degradation trend of proton exchange membrane fuel...In this paper,a fusion model based on a long short-term memory(LSTM)neural network and enhanced search ant colony optimization(ENSACO)is proposed to predict the power degradation trend of proton exchange membrane fuel cells(PEMFC).Firstly,the Shapley additive explanations(SHAP)value method is used to select external characteristic parameters with high contributions as inputs for the data-driven approach.Next,a novel swarm optimization algorithm,the enhanced search ant colony optimization,is proposed.This algorithm improves the ant colony optimization(ACO)algorithm based on a reinforcement factor to avoid premature convergence and accelerate the convergence speed.Comparative experiments are set up to compare the performance differences between particle swarm optimization(PSO),ACO,and ENSACO.Finally,a data-driven method based on ENSACO-LSTM is proposed to predict the power degradation trend of PEMFCs.And actual aging data is used to validate the method.The results show that,within a limited number of iterations,the optimization capability of ENSACO is significantly stronger than that of PSO and ACO.Additionally,the prediction accuracy of the ENSACO-LSTM method is greatly improved,with an average increase of approximately 50.58%compared to LSTM,PSO-LSTM,and ACO-LSTM.展开更多
When the proton exchange membrane fuel cell(PEMFC)system is running,there will be a condition that does not require power output for a short time.In order to achieve zero power output under low power consumption,it is...When the proton exchange membrane fuel cell(PEMFC)system is running,there will be a condition that does not require power output for a short time.In order to achieve zero power output under low power consumption,it is necessary to consider the diversity of control targets and the complexity of dynamic models,which brings the challenge of high-precision tracking control of the stack output power and cathode intake flow.For system idle speed control,a modelbased nonlinear control framework is constructed in this paper.Firstly,the nonlinear dynamic model of output power and cathode intake flow is derived.Secondly,a control scheme combining nonlinear extended Kalman filter observer and state feedback controller is designed.Finally,the control scheme is verified on the PEMFC experimental platform and compared with the proportion-integration-differentiation(PID)controller.The experimental results show that the control strategy proposed in this paper can realize the idle speed control of the fuel cell system and achieve the purpose of zero power output.Compared with PID controller,it has faster response speed and better system dynamics.展开更多
Removing copper from nickel electrolysis anode solution has been a major keypoint in the nickel metallurgy industry.In this study,we proposed a novel process flow to promote removing copper from nickel electrolysis an...Removing copper from nickel electrolysis anode solution has been a major keypoint in the nickel metallurgy industry.In this study,we proposed a novel process flow to promote removing copper from nickel electrolysis anode solution.A simulated nickel anode solution was designed,and static and dynamic adsorption experiments were conducted to determine the best of solution pH,adsorption time and temperature,resin dosage and particle size,and stirring speed.The optimal conditions were explored for copper removal from nickel electrolysis anode solution.Based on the optimal experimental conditions and the relevant experimental data,a novel process for copper removal from nickel electrolysis anodes was designed and verified.This novel process of copper removal from nickel electrolysis anodes was confirmed with nickel anolyte solution with nickel 50−60 g/L and copper 0.5 g/L.After finishing the novel process of copper removal,the nickel in the purified nickel anolyte became undetectable and copper concentration was 3 mg/L,the novel process of resin adsorption to remove copper from nickel anode solution through static and dynamic adsorptions has an efficacious copper removal.It is a beneficial supplement to traditional methods.展开更多
The purpose of the covert communication scheme is to conceal the communication behavior entirely.In such schemes,the sender and receiver rely on secret keys to establish a covert channel.However,conventional key excha...The purpose of the covert communication scheme is to conceal the communication behavior entirely.In such schemes,the sender and receiver rely on secret keys to establish a covert channel.However,conventional key exchange protocols would expose the key exchange process between them.An adversary who observes the key exchange would be aware of the existence of communication behavior.The keys used in covert communication are not suitable to be generated through conventional key exchange schemes.To address this,we propose a blockchain-based covert elliptic-curve Diffie-Hellman key exchange scheme(BCDH)to conceal the process of the key exchange in blockchain transactions.Following a straightforward setup,BCDH allows the sender and receiver to covertly exchange a secret key on a blockchain without direct communication.Furthermore,we expand the BCDH approach to operate across multiple blockchains,further enhancing its covertness and stability.We analyze BCDH from several perspectives,including covertness,security,randomness,etc.Additionally,we implement a prototype of BCDH on the Ethereum platform to assess its feasibility and performance.Our evaluation demonstrates that BCDH is efficient and well-suited for real-world applications.展开更多
The effect of temperature on Na/Li ion exchange reaction and behavior for the Li1.3Zr1.7Al0.3(PO4)3 in sodium chloride and lithium chloride solution was investigated and no obvious effect was observed on the Na/Li ion...The effect of temperature on Na/Li ion exchange reaction and behavior for the Li1.3Zr1.7Al0.3(PO4)3 in sodium chloride and lithium chloride solution was investigated and no obvious effect was observed on the Na/Li ion exchange reaction for Li1.3Zr1.7Al0.3(PO4)3. The Na/Li ion exchange reaction process of Li1.3Zr1.7Al0.3(PO4)3 was studied by means of X-ray diffraction (XRD). The ion exchange kinetics of Na/Li for Li1.3Zr1.7Al0.3(PO4)3 is analyzed and discussed.展开更多
在电子商务交易中,为了防止交易抵赖,保证买卖双方在交易时的公平性,半可信/可信的第三方(简称TTP,a Trusted Third Party)担任着重要的角色。半可信第三方协议中的Exchange协议、Abort协议、Resolve协议以及TTP的Inline TTP-Coffey-Sai...在电子商务交易中,为了防止交易抵赖,保证买卖双方在交易时的公平性,半可信/可信的第三方(简称TTP,a Trusted Third Party)担任着重要的角色。半可信第三方协议中的Exchange协议、Abort协议、Resolve协议以及TTP的Inline TTP-Coffey-Saidha协议在电子商务中,结合Esign数字签名和加密技术确保电子交易的公正性、公平性、安全性和可靠性。展开更多
基金supported by the National Natural Science Foundation of China(Grant No.12301603).
文摘In this paper,we study the optimal investment problem of an insurer whose surplus process follows the diffusion approximation of the classical Cramer-Lundberg model.Investment in the foreign markets is allowed,and therefore,the foreign exchange rate model is incorporated.Under the allowing of selling and borrowing,the problem of maximizing the expected exponential utility of terminal wealth is studied.By solving the corresponding Hamilton-Jacobi-Bellman equations,the optimal investment strategies and value functions are obtained.Finally,numerical analysis is presented.
文摘High-quality antiferromagnetic(AFM)θ-phase manganese nitride(MnN)films were successfully grown on MgO(001)substrates by plasma-assisted molecular beam epitaxy.Structural analysis confirms the high-quality MnN film has a tetragonal distortion with a c/a ratio of~0.98.The film exhibits exceptional stability in both aqueous and ambient conditions,which is a crucial factor for practical applications.Electrical transport reveals its metallic behavior with an upturn at low temperatures,which could be attributed to the Kondo effect originated from nitrogen vacancy-induced magnetic impurities.Room temperature exchange bias has been demonstrated in a MnN/CoFeB heterostructure,verifying the AFM ordering of MnN.Considering its high Néel temperature~650 K,superior stability,and low-cost,this work highlights the epitaxial MnN films as a promising candidate for AFM spintronic applications.
基金the National Key Research and Development Program of China(2022YFB4004100)National Natural Science Foundation of China(22272161,22179126)+1 种基金the Jilin Province Science and Technology Development Program(YDZJ202202CXJD011,20240101019JC)Jilin Province major science and technology project(222648GX0105103875)for financial supports.
文摘The weak adsorption energy of oxygen-containing intermediates on Co center leads to a considerable performance dis-parity between Co-N-C and costly Pt benchmark in catalyzing oxygen reduction reaction(ORR).In this work,we strategi-cally engineer the active site structure of Co-N-C via B substitution,which is accomplished by the pyrolysis of ammonium borate.During this process,the in-situ generated NH_(3)gas plays a critical role in creating surface defects and boron atoms substituting nitrogen atoms in the carbon structure.The well-designed CoB_(1)N_(3)active site endows Co with higher charge density and stronger adsorption energy toward oxygen species,potentially accelerating ORR kinetics.As expected,the resulting Co-B/N-C catalyst exhibited superior ORR performance over Co-N-C counterpart,with 40 mV,and fivefold en-hancement in half-wave potential and turnover frequency(TOF).More importantly,the excellent ORR performance could be translated into membrane electrode assembly(MEA)in a fuel cell test,delivering an impressive peak power density of 824 mW·cm^(-2),which is currently the best among Co-based catalysts under the same conditions.This work not only demon-strates an effective method for designing advanced catalysts,but also affords a highly promising non-precious metal ORR electrocatalyst for fuel cell applications.
基金Supported by the Major Science and Technology Project of Jilin Province(20220301010GX)the International Scientific and Technological Cooperation(20240402071GH).
文摘In this paper,a fusion model based on a long short-term memory(LSTM)neural network and enhanced search ant colony optimization(ENSACO)is proposed to predict the power degradation trend of proton exchange membrane fuel cells(PEMFC).Firstly,the Shapley additive explanations(SHAP)value method is used to select external characteristic parameters with high contributions as inputs for the data-driven approach.Next,a novel swarm optimization algorithm,the enhanced search ant colony optimization,is proposed.This algorithm improves the ant colony optimization(ACO)algorithm based on a reinforcement factor to avoid premature convergence and accelerate the convergence speed.Comparative experiments are set up to compare the performance differences between particle swarm optimization(PSO),ACO,and ENSACO.Finally,a data-driven method based on ENSACO-LSTM is proposed to predict the power degradation trend of PEMFCs.And actual aging data is used to validate the method.The results show that,within a limited number of iterations,the optimization capability of ENSACO is significantly stronger than that of PSO and ACO.Additionally,the prediction accuracy of the ENSACO-LSTM method is greatly improved,with an average increase of approximately 50.58%compared to LSTM,PSO-LSTM,and ACO-LSTM.
基金Supported by the Major Science and Technology Projects in Jilin Province and Changchun City(20220301010GX).
文摘When the proton exchange membrane fuel cell(PEMFC)system is running,there will be a condition that does not require power output for a short time.In order to achieve zero power output under low power consumption,it is necessary to consider the diversity of control targets and the complexity of dynamic models,which brings the challenge of high-precision tracking control of the stack output power and cathode intake flow.For system idle speed control,a modelbased nonlinear control framework is constructed in this paper.Firstly,the nonlinear dynamic model of output power and cathode intake flow is derived.Secondly,a control scheme combining nonlinear extended Kalman filter observer and state feedback controller is designed.Finally,the control scheme is verified on the PEMFC experimental platform and compared with the proportion-integration-differentiation(PID)controller.The experimental results show that the control strategy proposed in this paper can realize the idle speed control of the fuel cell system and achieve the purpose of zero power output.Compared with PID controller,it has faster response speed and better system dynamics.
基金Project(2019yff0216502)supported by the National Key Research&Development Plan of Ministry of Science and Technology of ChinaProject(2021SK1020-4)supported by the Major Science and Technological Innovation Project of Hunan Province,China。
文摘Removing copper from nickel electrolysis anode solution has been a major keypoint in the nickel metallurgy industry.In this study,we proposed a novel process flow to promote removing copper from nickel electrolysis anode solution.A simulated nickel anode solution was designed,and static and dynamic adsorption experiments were conducted to determine the best of solution pH,adsorption time and temperature,resin dosage and particle size,and stirring speed.The optimal conditions were explored for copper removal from nickel electrolysis anode solution.Based on the optimal experimental conditions and the relevant experimental data,a novel process for copper removal from nickel electrolysis anodes was designed and verified.This novel process of copper removal from nickel electrolysis anodes was confirmed with nickel anolyte solution with nickel 50−60 g/L and copper 0.5 g/L.After finishing the novel process of copper removal,the nickel in the purified nickel anolyte became undetectable and copper concentration was 3 mg/L,the novel process of resin adsorption to remove copper from nickel anode solution through static and dynamic adsorptions has an efficacious copper removal.It is a beneficial supplement to traditional methods.
文摘The purpose of the covert communication scheme is to conceal the communication behavior entirely.In such schemes,the sender and receiver rely on secret keys to establish a covert channel.However,conventional key exchange protocols would expose the key exchange process between them.An adversary who observes the key exchange would be aware of the existence of communication behavior.The keys used in covert communication are not suitable to be generated through conventional key exchange schemes.To address this,we propose a blockchain-based covert elliptic-curve Diffie-Hellman key exchange scheme(BCDH)to conceal the process of the key exchange in blockchain transactions.Following a straightforward setup,BCDH allows the sender and receiver to covertly exchange a secret key on a blockchain without direct communication.Furthermore,we expand the BCDH approach to operate across multiple blockchains,further enhancing its covertness and stability.We analyze BCDH from several perspectives,including covertness,security,randomness,etc.Additionally,we implement a prototype of BCDH on the Ethereum platform to assess its feasibility and performance.Our evaluation demonstrates that BCDH is efficient and well-suited for real-world applications.
文摘The effect of temperature on Na/Li ion exchange reaction and behavior for the Li1.3Zr1.7Al0.3(PO4)3 in sodium chloride and lithium chloride solution was investigated and no obvious effect was observed on the Na/Li ion exchange reaction for Li1.3Zr1.7Al0.3(PO4)3. The Na/Li ion exchange reaction process of Li1.3Zr1.7Al0.3(PO4)3 was studied by means of X-ray diffraction (XRD). The ion exchange kinetics of Na/Li for Li1.3Zr1.7Al0.3(PO4)3 is analyzed and discussed.
文摘在电子商务交易中,为了防止交易抵赖,保证买卖双方在交易时的公平性,半可信/可信的第三方(简称TTP,a Trusted Third Party)担任着重要的角色。半可信第三方协议中的Exchange协议、Abort协议、Resolve协议以及TTP的Inline TTP-Coffey-Saidha协议在电子商务中,结合Esign数字签名和加密技术确保电子交易的公正性、公平性、安全性和可靠性。
