Risk management often plays an important role in decision making un-der uncertainty.In quantitative risk management,assessing and optimizing risk metrics requires eficient computing techniques and reliable theoretical...Risk management often plays an important role in decision making un-der uncertainty.In quantitative risk management,assessing and optimizing risk metrics requires eficient computing techniques and reliable theoretical guarantees.In this pa-per,we introduce several topics on quantitative risk management and review some of the recent studies and advancements on the topics.We consider several risk metrics and study decision models that involve the metrics,with a main focus on the related com-puting techniques and theoretical properties.We show that stochastic optimization,as a powerful tool,can be leveraged to effectively address these problems.展开更多
In order to enhance the control performance of piezo-positioning system,the influence of hysteresis characteristics and its compensation method are studied.Hammerstein model is used to represent the dynamic hysteresis...In order to enhance the control performance of piezo-positioning system,the influence of hysteresis characteristics and its compensation method are studied.Hammerstein model is used to represent the dynamic hysteresis nonlinear characteristics of piezo-positioning actuator.The static nonlinear part and dynamic linear part of the Hammerstein model are represented by models obtained through the Prandtl-Ishlinskii(PI)model and Hankel matrix system identification method,respectively.This model demonstrates good generalization capability for typical input frequencies below 200 Hz.A sliding mode inverse compensation tracking control strategy based on P-I inverse model and integral augmentation is proposed.Experimental results show that compared with PID inverse compensation control and sliding mode control without inverse compensation,the sliding mode inverse compensation control has a more ideal step response and no overshoot,moreover,the settling time is only 6.2 ms.In the frequency domain,the system closed-loop tracking bandwidth reaches 119.9 Hz,and the disturbance rejection bandwidth reaches 86.2 Hz.The proposed control strategy can effectively compensate the hysteresis nonlinearity,and improve the tracking accuracy and antidisturbance capability of piezo-positioning system.展开更多
The effect of external vibration on the velocity uniformity of the moving mechanism of the angular mir⁃ror translational Fourier transform interferometer(hereinafter referred to as interferometer)can be quantitatively...The effect of external vibration on the velocity uniformity of the moving mechanism of the angular mir⁃ror translational Fourier transform interferometer(hereinafter referred to as interferometer)can be quantitatively analysed by the interferometer optical range difference velocity stability.The article proposes a more comprehen⁃sive method of analysing the optical range difference velocity uniformity for the reliability of the interferometer ki⁃nematic mechanism under the influence of on-orbit microvibration in the process of space spectroscopy detection.The method incorporates the structural response of the interferometer caused by external excitation into the stabili⁃ty analysis as one of the influencing factors,so as to reflect the reliability of the interferometer in orbit more realis⁃tically,and judge the microvibration criticality that the interferometer can withstand more accurately.At the same time,an optical surface model of the interferometer is established to further theoretically characterise the effect of microvibration on the homogeneity of the interferometric mechanism.The method discussed in the article pro⁃vides a way of thinking for the judgement of the reliability of the mechanism movement under the external excita⁃tion perturbation as well as the research on the optimisation of the mechanism control.展开更多
In this paper,we develop a multi-scalar auxiliary variables(MSAV)scheme for the Cahn-Hilliard Magnetohydrodynamics system by introducing two scalar auxiliary variables(SAV).This scheme is linear,fully decoupled and un...In this paper,we develop a multi-scalar auxiliary variables(MSAV)scheme for the Cahn-Hilliard Magnetohydrodynamics system by introducing two scalar auxiliary variables(SAV).This scheme is linear,fully decoupled and unconditionally stable in energy.Subsequently,we provide a detailed implementation procedure for full decoupling.Thus,at each time step,only a series of linear differential equations with constant coefficients need to be solved.To validate the effectiveness of our approach,we conduct an error analysis for this first-order scheme.Finally,some numerical experiments are provided to verify the energy dissipation of the system and the convergence of the proposed approach.展开更多
Perilla essential oil(PEO)is reported as an aromatic yellowish oily substance with a volatile odor extracted from perilla leaves.It exhibits various biological activities except anti-tobacco mosaic virus(TMV)activity....Perilla essential oil(PEO)is reported as an aromatic yellowish oily substance with a volatile odor extracted from perilla leaves.It exhibits various biological activities except anti-tobacco mosaic virus(TMV)activity.In this study,we investigated the main components and anti-TMV activity of PEO,identified its primary active components,and examined its mode of action.The results indicated that PEO exhibited anti-TMV activity(65.58%)at 800μg/mL,with perillaldehyde identified as the main active component.The protective,curative,and inactivation activities of perillaldehyde at 800μg/mL were 80.41%,73.42%,and 34.93%,respectively.These values were significantly higher than those of the control drug(commercial chitosan oligosaccharide)and the protective and curative activities were superior to those of ningnanmycin.The results of the mode of action showed that perillaldehyde induced a hypersensitive response(HR)in tobacco.Transmission electron microscope(TEM)observation revealed that perillaldehyde had no direct effect on TMV particles.The treatment of Nicotiana glutinosa with perillaldehyde at 800μg/mL indicated that perillaldehyde had significant induction activity(58.46%).The expression of three pathogenesis-related tobacco genes(PR genes),including nonexpressor of pathogenesis-related genes 1(NPR1),pathogenesis-related protein 1 gene(PR1),and pathogenesis-related protein 5 gene(PR5),were induced and upregulated by perillaldehyde treatment.Perillaldehyde also induced the overexpression of the phenylalanine ammonia-lyase gene(PAL),respiratory burst oxidase homolog B gene(RBOHB),and protochlorophyllide oxidoreductase gene 1(POR1).Furthermore,perillaldehyde increased the salicylic acid(SA)and H2O2 contents in tobacco leaves,and enhanced the activities of four defense enzymes:superoxide dismutase(SOD),catalase(CAT),peroxidase(POD),and phenylalanine ammonia-lyase(PAL).N.glutinosa was treated with perillaldehyde at 800μg/mL for 24 h,and the results showed that the highest SA and H_(2)O_(2) contents(1032.08 pmol/L and 23.40μmol/g FW,respectively)were obtained in tobacco leaves.Defense enzyme activities also reached a maximum at 800μg/mL,and the activities of CAT,PAL,POD,and SOD increased by 1.76,1.95,2.17,and 3.78 times,respectively,compared to the control.The results of the study showed that perillaldehyde may enhance resistance to pathogen infection by inducing systemic acquired resistance(SAR),which may contribute to the activation of SA signal transduction pathway.Therefore,perillaldehyde has the potential for application in agriculture as a novel antiviral agent and immune inducer.展开更多
Since social media increasingly infiltrates the workplace,it may affect employee innovation.However,how so-cial media use(SMU)affects employee innovation performance remains controversial.Therefore,this study explores...Since social media increasingly infiltrates the workplace,it may affect employee innovation.However,how so-cial media use(SMU)affects employee innovation performance remains controversial.Therefore,this study explores the underlying mechanisms and boundary conditions in the relationship between SMU and employee innovation performance.The research model was tested through a survey of 221 Chinese employees.The results show that SMU is positively re-lated to employee innovation performance,with work engagement acting as a mediator in this relationship.Employee tra-ditionality positively moderates the positive impact of work-related SMU on work engagement,while traditionality has no moderating effect on the relationship between social-related SMU and work engagement.This study focuses on the rela-tionship between SMU and innovation performance based on conservation of resources theory,offering insights into the intrinsic mechanism by which SMU affects employee innovation.Furthermore,this study considers the moderating effect of employee traditionality based on social cognitive theory,enriching the knowledge of how traditionality influences the impacts of SMU.This study has theoretical implications for future research and practical guidance for enterprises regard-ing the proper use of social media.展开更多
Attackers inject the designed adversarial sample into the target recommendation system to achieve illegal goals,seriously affecting the security and reliability of the recommendation system.It is difficult for attacke...Attackers inject the designed adversarial sample into the target recommendation system to achieve illegal goals,seriously affecting the security and reliability of the recommendation system.It is difficult for attackers to obtain detailed knowledge of the target model in actual scenarios,so using gradient optimization to generate adversarial samples in the local surrogate model has become an effective black‐box attack strategy.However,these methods suffer from gradients falling into local minima,limiting the transferability of the adversarial samples.This reduces the attack's effectiveness and often ignores the imperceptibility of the generated adversarial samples.To address these challenges,we propose a novel attack algorithm called PGMRS‐KL that combines pre‐gradient‐guided momentum gradient optimization strategy and fake user generation constrained by Kullback‐Leibler divergence.Specifically,the algorithm combines the accumulated gradient direction with the previous step's gradient direction to iteratively update the adversarial samples.It uses KL loss to minimize the distribution distance between fake and real user data,achieving high transferability and imperceptibility of the adversarial samples.Experimental results demonstrate the superiority of our approach over state‐of‐the‐art gradient‐based attack algorithms in terms of attack transferability and the generation of imperceptible fake user data.展开更多
文摘Risk management often plays an important role in decision making un-der uncertainty.In quantitative risk management,assessing and optimizing risk metrics requires eficient computing techniques and reliable theoretical guarantees.In this pa-per,we introduce several topics on quantitative risk management and review some of the recent studies and advancements on the topics.We consider several risk metrics and study decision models that involve the metrics,with a main focus on the related com-puting techniques and theoretical properties.We show that stochastic optimization,as a powerful tool,can be leveraged to effectively address these problems.
文摘In order to enhance the control performance of piezo-positioning system,the influence of hysteresis characteristics and its compensation method are studied.Hammerstein model is used to represent the dynamic hysteresis nonlinear characteristics of piezo-positioning actuator.The static nonlinear part and dynamic linear part of the Hammerstein model are represented by models obtained through the Prandtl-Ishlinskii(PI)model and Hankel matrix system identification method,respectively.This model demonstrates good generalization capability for typical input frequencies below 200 Hz.A sliding mode inverse compensation tracking control strategy based on P-I inverse model and integral augmentation is proposed.Experimental results show that compared with PID inverse compensation control and sliding mode control without inverse compensation,the sliding mode inverse compensation control has a more ideal step response and no overshoot,moreover,the settling time is only 6.2 ms.In the frequency domain,the system closed-loop tracking bandwidth reaches 119.9 Hz,and the disturbance rejection bandwidth reaches 86.2 Hz.The proposed control strategy can effectively compensate the hysteresis nonlinearity,and improve the tracking accuracy and antidisturbance capability of piezo-positioning system.
文摘The effect of external vibration on the velocity uniformity of the moving mechanism of the angular mir⁃ror translational Fourier transform interferometer(hereinafter referred to as interferometer)can be quantitatively analysed by the interferometer optical range difference velocity stability.The article proposes a more comprehen⁃sive method of analysing the optical range difference velocity uniformity for the reliability of the interferometer ki⁃nematic mechanism under the influence of on-orbit microvibration in the process of space spectroscopy detection.The method incorporates the structural response of the interferometer caused by external excitation into the stabili⁃ty analysis as one of the influencing factors,so as to reflect the reliability of the interferometer in orbit more realis⁃tically,and judge the microvibration criticality that the interferometer can withstand more accurately.At the same time,an optical surface model of the interferometer is established to further theoretically characterise the effect of microvibration on the homogeneity of the interferometric mechanism.The method discussed in the article pro⁃vides a way of thinking for the judgement of the reliability of the mechanism movement under the external excita⁃tion perturbation as well as the research on the optimisation of the mechanism control.
基金Research Project Supported by Shanxi Scholarship Council of China(2021-029)International Cooperation Base and Platform Project of Shanxi Province(202104041101019)Basic Research Plan of Shanxi Province(202203021211129)。
文摘In this paper,we develop a multi-scalar auxiliary variables(MSAV)scheme for the Cahn-Hilliard Magnetohydrodynamics system by introducing two scalar auxiliary variables(SAV).This scheme is linear,fully decoupled and unconditionally stable in energy.Subsequently,we provide a detailed implementation procedure for full decoupling.Thus,at each time step,only a series of linear differential equations with constant coefficients need to be solved.To validate the effectiveness of our approach,we conduct an error analysis for this first-order scheme.Finally,some numerical experiments are provided to verify the energy dissipation of the system and the convergence of the proposed approach.
基金Supported by National Natural Science Foundation of China(No.32072444)National Natural Science Foundation of China(No.32060429)the key Project of Natural Science Foundation of Xinjiang Uygur Autonomous Region(No.2022D01D44).
文摘Perilla essential oil(PEO)is reported as an aromatic yellowish oily substance with a volatile odor extracted from perilla leaves.It exhibits various biological activities except anti-tobacco mosaic virus(TMV)activity.In this study,we investigated the main components and anti-TMV activity of PEO,identified its primary active components,and examined its mode of action.The results indicated that PEO exhibited anti-TMV activity(65.58%)at 800μg/mL,with perillaldehyde identified as the main active component.The protective,curative,and inactivation activities of perillaldehyde at 800μg/mL were 80.41%,73.42%,and 34.93%,respectively.These values were significantly higher than those of the control drug(commercial chitosan oligosaccharide)and the protective and curative activities were superior to those of ningnanmycin.The results of the mode of action showed that perillaldehyde induced a hypersensitive response(HR)in tobacco.Transmission electron microscope(TEM)observation revealed that perillaldehyde had no direct effect on TMV particles.The treatment of Nicotiana glutinosa with perillaldehyde at 800μg/mL indicated that perillaldehyde had significant induction activity(58.46%).The expression of three pathogenesis-related tobacco genes(PR genes),including nonexpressor of pathogenesis-related genes 1(NPR1),pathogenesis-related protein 1 gene(PR1),and pathogenesis-related protein 5 gene(PR5),were induced and upregulated by perillaldehyde treatment.Perillaldehyde also induced the overexpression of the phenylalanine ammonia-lyase gene(PAL),respiratory burst oxidase homolog B gene(RBOHB),and protochlorophyllide oxidoreductase gene 1(POR1).Furthermore,perillaldehyde increased the salicylic acid(SA)and H2O2 contents in tobacco leaves,and enhanced the activities of four defense enzymes:superoxide dismutase(SOD),catalase(CAT),peroxidase(POD),and phenylalanine ammonia-lyase(PAL).N.glutinosa was treated with perillaldehyde at 800μg/mL for 24 h,and the results showed that the highest SA and H_(2)O_(2) contents(1032.08 pmol/L and 23.40μmol/g FW,respectively)were obtained in tobacco leaves.Defense enzyme activities also reached a maximum at 800μg/mL,and the activities of CAT,PAL,POD,and SOD increased by 1.76,1.95,2.17,and 3.78 times,respectively,compared to the control.The results of the study showed that perillaldehyde may enhance resistance to pathogen infection by inducing systemic acquired resistance(SAR),which may contribute to the activation of SA signal transduction pathway.Therefore,perillaldehyde has the potential for application in agriculture as a novel antiviral agent and immune inducer.
基金supported by the National Natural Science Foundation of China(72332007)。
文摘Since social media increasingly infiltrates the workplace,it may affect employee innovation.However,how so-cial media use(SMU)affects employee innovation performance remains controversial.Therefore,this study explores the underlying mechanisms and boundary conditions in the relationship between SMU and employee innovation performance.The research model was tested through a survey of 221 Chinese employees.The results show that SMU is positively re-lated to employee innovation performance,with work engagement acting as a mediator in this relationship.Employee tra-ditionality positively moderates the positive impact of work-related SMU on work engagement,while traditionality has no moderating effect on the relationship between social-related SMU and work engagement.This study focuses on the rela-tionship between SMU and innovation performance based on conservation of resources theory,offering insights into the intrinsic mechanism by which SMU affects employee innovation.Furthermore,this study considers the moderating effect of employee traditionality based on social cognitive theory,enriching the knowledge of how traditionality influences the impacts of SMU.This study has theoretical implications for future research and practical guidance for enterprises regard-ing the proper use of social media.
基金The National Natural Science Foundation of China (61876001)Opening Foundation of State Key Laboratory of Cognitive Intelligence,Opening Foundation of State Key Laboratory of Cognitive Intelligence(iED2022-006)Scientific Research Planning Project of Anhui Province (2022AH050072)
文摘Attackers inject the designed adversarial sample into the target recommendation system to achieve illegal goals,seriously affecting the security and reliability of the recommendation system.It is difficult for attackers to obtain detailed knowledge of the target model in actual scenarios,so using gradient optimization to generate adversarial samples in the local surrogate model has become an effective black‐box attack strategy.However,these methods suffer from gradients falling into local minima,limiting the transferability of the adversarial samples.This reduces the attack's effectiveness and often ignores the imperceptibility of the generated adversarial samples.To address these challenges,we propose a novel attack algorithm called PGMRS‐KL that combines pre‐gradient‐guided momentum gradient optimization strategy and fake user generation constrained by Kullback‐Leibler divergence.Specifically,the algorithm combines the accumulated gradient direction with the previous step's gradient direction to iteratively update the adversarial samples.It uses KL loss to minimize the distribution distance between fake and real user data,achieving high transferability and imperceptibility of the adversarial samples.Experimental results demonstrate the superiority of our approach over state‐of‐the‐art gradient‐based attack algorithms in terms of attack transferability and the generation of imperceptible fake user data.
