This paper addresses a problem of observer-based sensor fault reconstruction for continuous-time systems subject to sensor faults and measurement disturbances via a descriptor system approach. An augmented descriptor ...This paper addresses a problem of observer-based sensor fault reconstruction for continuous-time systems subject to sensor faults and measurement disturbances via a descriptor system approach. An augmented descriptor plant is first formulated, by assembling measurement disturbances and sensor faults into an auxiliary state vector. Then a novel descriptor state observer for the augmented plant is constructed such that simultaneous reconstruction of original system states, sensor faults and measurement disturbances are obtained readily. Sufficient conditions for the existence of the proposed observer are explicitly provided, and the application scope of the observer is further discussed. In addition, an extension of the proposed linear approach to a class of nonlinear systems with Lipschitz constraints is investigated. Finally, two numerical examples are simulated to illustrate the effectiveness of the proposed fault-reconstructing approaches.展开更多
We present the thermal expansion coefficient （TEC） measurement technology of compensating for the effect of variations in the refractive index based on a Nd： YA G laser feedback system, the beam frequency is shifte...We present the thermal expansion coefficient （TEC） measurement technology of compensating for the effect of variations in the refractive index based on a Nd： YA G laser feedback system, the beam frequency is shifted by a pair of aeousto-optic modulators and then the heterodyne phase measurement technique is used. The sample measured is placed in a muffle furnace with two coaxial holes opened on the opposite furnace walls. The measurement beams hit perpendicularly and coaxially on each surface of the sample. The reference beams hit on the reference mirror and the high-refiectivity mirror, respectively. By the heterodyne configuration and computing, the influences of the vibration, distortion of the sample supporter and the effect of variations in the refractive index are measured and largely minimized. For validation, the TECs of aluminum samples are determined in the temperature range of 29-748K, confirming not only the precision within 5 × 10-7 K-1 and the accuracy within 0.4% from 298K to 448K but also the high sensitivity non-contact measurement of the lower reflectivity surface induced by the sample oxidization from 448 K to 748 K.展开更多
The optical frequency comb has been widely used in precision measurement. In this study, a multi-peak fitting approach is first proposed to fit the two-photon transition spectrum which overlaps with the neighboring tr...The optical frequency comb has been widely used in precision measurement. In this study, a multi-peak fitting approach is first proposed to fit the two-photon transition spectrum which overlaps with the neighboring transition in Rb-87. The multi-peak fitting approach is used to eliminate the frequency shift affected by the neighboring transition. With locking the carrier envelope offset frequency at 1/4 repetition frequency, the transition frequency is measured to be 770569132739.9 +/- 5.8 kHz, which agrees well with the previous result recommended by Comite International des Poids et Mesures.展开更多
We are in the midst of a significant transformation regarding the way we produce products and deliver services thanks to the digitization of manufacturing and new connected supply-chains and co-creation systems.This a...We are in the midst of a significant transformation regarding the way we produce products and deliver services thanks to the digitization of manufacturing and new connected supply-chains and co-creation systems.This article elaborates Digital Twins Approach to the current challenges of knowledge management when Industry 4.0 is emerging in industries and manufacturing.Industry 4.0 approach underlines the importance of Internet of Things and interactions between social and physical systems.Internet of Things(and also Internet of Services and Internet of Data)are new Internet infrastructure that marries advanced manufacturing techniques and service architectures with the I-o-T,I-o-S,and I-o-D to create manufacturing systems that are not only interconnected,but communicate,analyze,and use information to drive further intelligent action back in the physical world.This paper identifies four critical domains of synergy challenge:(1)man-to-man interaction;(2)man-to-machine interaction;(3)machine-to-man interaction;and finally(4)machine-to-machine interaction.Key conclusion is that new knowledge management challenges are closely linked to the challenges of synergic interactions between these four key interactions and accurate measurements of synergic interaction.展开更多
A new method of phase measurement based on optimization is presented. Simulations were ran with synthesized signals, and comparison was made with some spectral domain methods. The results show that, with a suitable n...A new method of phase measurement based on optimization is presented. Simulations were ran with synthesized signals, and comparison was made with some spectral domain methods. The results show that, with a suitable number of samples processed, this method is superior to other methods in terms of accuracy, while the amplitude and phase of distortion component have no effect on accuracy.展开更多
To recognize and measure the potential share value of conversion for convertible bonds more accurately,different approaches such as the straight method,the separating method,the expected value approach and the improve...To recognize and measure the potential share value of conversion for convertible bonds more accurately,different approaches such as the straight method,the separating method,the expected value approach and the improved approach are comparatively analyzed by taking China Merchants Bank's convertible bonds as an example.There is also a focus on the improved approach that views that convertible bond issue proceeds can be separated into accrual debt value,accrual equity value and accrual option value according to the characteristics of debt,equity and hybrid securities with embedded options of convertible bonds.It is concluded that the improved approach is a more accurate evaluation method of capital structure so that it can fully reflect the economic reality of convertible bonds.展开更多
This paper introduces a new approach for measuring shareholder value creation （called adjusted economic profit （EP）） which combines the advantages of both EP and APV （adjusted present value） methods. In particul...This paper introduces a new approach for measuring shareholder value creation （called adjusted economic profit （EP）） which combines the advantages of both EP and APV （adjusted present value） methods. In particular, the shareholder value creation over a period is derived as the sum of two components： the EP relating purely to the operations of the company and the EP generated each period due to the tax benefit that arises from debt financing. We consider our results to be important for analysts and decision makers involved in appraising business performance or making investment decisions and HR professionals as well.展开更多
There are many reasons whymerchant ships make desirable targetsfor pirates and terrorists as well as aconvenient means of transport for thestowaway. Criminal activity in the form ofsuch threats is quickly becoming one...There are many reasons whymerchant ships make desirable targetsfor pirates and terrorists as well as aconvenient means of transport for thestowaway. Criminal activity in the form ofsuch threats is quickly becoming one ofthe greatest threats to ships and展开更多
In recent years, the college English teaching reform has been increasingly deepened. The study of the relationship between cognitive approach and foreign language teaching is undoubtedly instructive not only to guaran...In recent years, the college English teaching reform has been increasingly deepened. The study of the relationship between cognitive approach and foreign language teaching is undoubtedly instructive not only to guarantee the quality of foreign language teaching but also to improve learners＇ foreign language proficiency. In this essay, the author expounds the development of cognitive approach and some relative teaching principles, on which basis the author puts forward some specific practices in foreign language teaching.展开更多
High harmonic generation(HHG)provides an experimental method for producing attosecond pulses and probing electron dynamics.Achieving precise dipole phase measurements is critical for tailoring the harmonic emission ph...High harmonic generation(HHG)provides an experimental method for producing attosecond pulses and probing electron dynamics.Achieving precise dipole phase measurements is critical for tailoring the harmonic emission phase and identifying the HHG mechanism.However,achieving this feature by applying traditional two-beam far-field interferometry to solid materials remains challenging.In this study,we present a novel interferometric approach that utilizes a single laser beam to excite two ZnO microwires(MWs)simultaneously,thereby generating coherent high-harmonic sources that form interference fringes in the far-field region.We leverage the diameter-dependent field-enhancement effect in MWs to measure the intensity-dependent fringe shift,revealing that the intraband current mechanism dominates the below-bandgap harmonic,whereas the interband polarization mechanism dominates the above-bandgap harmonic.This study offers a robust method for measuring the dipole phase of solid-state HHG and inspires intensity-modulated high-harmonic applications in coherent imaging and microdevice design.展开更多
A learning-based approach for solving wall shear stresses from Shear-Sensitive Liquid Crystal Coating(SSLCC) color images is presented in this paper. The approach is able to learn and establish the mapping relationshi...A learning-based approach for solving wall shear stresses from Shear-Sensitive Liquid Crystal Coating(SSLCC) color images is presented in this paper. The approach is able to learn and establish the mapping relationship between the SSLCC color-change responses in different observation directions and the shear stress vectors, and then uses the mapping relationship to solve wall shear stress vectors from SSLCC color images. Experimental results show that the proposed approach can solve wall shear stress vectors using two or more SSLCC images, and even using only one image for symmetrical flow field. The accuracy of the approach using four or more observations is found to be comparable to that of the traditional multi-view Gauss curve fitting approach;the accuracy is slightly reduced when using two or fewer observations. The computational efficiency is significantly improved when compared with the traditional Gauss curve fitting approach, and the wall shear stress vectors can be solved in nearly real time. The learning-based approach has no strict requirements on illumination direction and observation directions and is therefore more flexible to use in practical wind tunnel measurement when compared with traditional liquid crystal-based methods.展开更多
Real-time 6 Degree-of-Freedom(DoF)pose estimation is of paramount importance for various on-orbit tasks.Benefiting from the development of deep learning,Convolutional Neural Networks(CNNs)in feature extraction has yie...Real-time 6 Degree-of-Freedom(DoF)pose estimation is of paramount importance for various on-orbit tasks.Benefiting from the development of deep learning,Convolutional Neural Networks(CNNs)in feature extraction has yielded impressive achievements for spacecraft pose estimation.To improve the robustness and interpretability of CNNs,this paper proposes a Pose Estimation approach based on Variational Auto-Encoder structure(PE-VAE)and a Feature-Aided pose estimation approach based on Variational Auto-Encoder structure(FA-VAE),which aim to accurately estimate the 6 DoF pose of a target spacecraft.Both methods treat the pose vector as latent variables,employing an encoder-decoder network with a Variational Auto-Encoder(VAE)structure.To enhance the precision of pose estimation,PE-VAE uses the VAE structure to introduce reconstruction mechanism with the whole image.Furthermore,FA-VAE enforces feature shape constraints by exclusively reconstructing the segment of the target spacecraft with the desired shape.Comparative evaluation against leading methods on public datasets reveals similar accuracy with a threefold improvement in processing speed,showcasing the significant contribution of VAE structures to accuracy enhancement,and the additional benefit of incorporating global shape prior features.展开更多
This paper presents a fixed-time equivalent-inputdisturbance(EID)approach to deal with the problem of robust output-feedback control for perturbed uncertain systems.This method uses the basic structure of the conventi...This paper presents a fixed-time equivalent-inputdisturbance(EID)approach to deal with the problem of robust output-feedback control for perturbed uncertain systems.This method uses the basic structure of the conventional EID approach and treats uncertainties and disturbances as a lumped disturbance on the control-input channel.A fixed-time state observer enables state estimation,which resolves the causality issue in an EID-based control system,is finished in a fixed time.An implicit Lyapunov function,the homogeneity with dilation,the input-tostate stability,and the small-gain theorem are used to analyze the convergence and robustness of the EID-based system with measurement noise.Numerical and experimental results are presented to demonstrate the effectiveness and superiority of the proposed method.展开更多
Globally,human,livestock,and wildlife interactions have been reported to result in innumerable forms of conflict and consequences.The most notable consequences are on the environment and human health,among others.The ...Globally,human,livestock,and wildlife interactions have been reported to result in innumerable forms of conflict and consequences.The most notable consequences are on the environment and human health,among others.The least developed countries,Tanzania inclusive,due to their bio-geographical and social characteristics,are mostly reported to register such consequences,which have sometimes led to zoonotic diseases due to the existence of risk factors.The factors include the growth of the human population,absence of infrastructural capacity,and skilled manpower to effectively deal with disease outbreaks and livestock keeping associated lifestyles.This article employs a documentary research method to analyse the human-wildlife conflict(HWC)and its consequences in Tanzania.It further assesses the potential of the One Health approach to curb the consequences of HWC following the introduction of One Health Strategic Plan(2015–2020).This article,therefore,analyses the potential for One Health approach to minimize the undesirable impacts of human,livestock,and wildlife interactions on health.This approach underscores the need for collaborative working efforts involving human,livestock,wildlife,and environmental health professionals and the need for a good understanding of the consequences of the interactions towards the realisation of optimum health for people,animals,and our environment.展开更多
基金supported by the National Natural Science Foundation of China(61104026)the Open Funding for National Defense Key Subject Laboratory of Micro and Small Spacecraft Technology(20090450126)
文摘This paper addresses a problem of observer-based sensor fault reconstruction for continuous-time systems subject to sensor faults and measurement disturbances via a descriptor system approach. An augmented descriptor plant is first formulated, by assembling measurement disturbances and sensor faults into an auxiliary state vector. Then a novel descriptor state observer for the augmented plant is constructed such that simultaneous reconstruction of original system states, sensor faults and measurement disturbances are obtained readily. Sufficient conditions for the existence of the proposed observer are explicitly provided, and the application scope of the observer is further discussed. In addition, an extension of the proposed linear approach to a class of nonlinear systems with Lipschitz constraints is investigated. Finally, two numerical examples are simulated to illustrate the effectiveness of the proposed fault-reconstructing approaches.
基金Supported by the National Natural Science Foundation of China under Grant No F050306
文摘We present the thermal expansion coefficient （TEC） measurement technology of compensating for the effect of variations in the refractive index based on a Nd： YA G laser feedback system, the beam frequency is shifted by a pair of aeousto-optic modulators and then the heterodyne phase measurement technique is used. The sample measured is placed in a muffle furnace with two coaxial holes opened on the opposite furnace walls. The measurement beams hit perpendicularly and coaxially on each surface of the sample. The reference beams hit on the reference mirror and the high-refiectivity mirror, respectively. By the heterodyne configuration and computing, the influences of the vibration, distortion of the sample supporter and the effect of variations in the refractive index are measured and largely minimized. For validation, the TECs of aluminum samples are determined in the temperature range of 29-748K, confirming not only the precision within 5 × 10-7 K-1 and the accuracy within 0.4% from 298K to 448K but also the high sensitivity non-contact measurement of the lower reflectivity surface induced by the sample oxidization from 448 K to 748 K.
基金Supported by the National Natural Science Foundation of China under Grant Nos 91336103,10934010 and 61078026
文摘The optical frequency comb has been widely used in precision measurement. In this study, a multi-peak fitting approach is first proposed to fit the two-photon transition spectrum which overlaps with the neighboring transition in Rb-87. The multi-peak fitting approach is used to eliminate the frequency shift affected by the neighboring transition. With locking the carrier envelope offset frequency at 1/4 repetition frequency, the transition frequency is measured to be 770569132739.9 +/- 5.8 kHz, which agrees well with the previous result recommended by Comite International des Poids et Mesures.
文摘We are in the midst of a significant transformation regarding the way we produce products and deliver services thanks to the digitization of manufacturing and new connected supply-chains and co-creation systems.This article elaborates Digital Twins Approach to the current challenges of knowledge management when Industry 4.0 is emerging in industries and manufacturing.Industry 4.0 approach underlines the importance of Internet of Things and interactions between social and physical systems.Internet of Things(and also Internet of Services and Internet of Data)are new Internet infrastructure that marries advanced manufacturing techniques and service architectures with the I-o-T,I-o-S,and I-o-D to create manufacturing systems that are not only interconnected,but communicate,analyze,and use information to drive further intelligent action back in the physical world.This paper identifies four critical domains of synergy challenge:(1)man-to-man interaction;(2)man-to-machine interaction;(3)machine-to-man interaction;and finally(4)machine-to-machine interaction.Key conclusion is that new knowledge management challenges are closely linked to the challenges of synergic interactions between these four key interactions and accurate measurements of synergic interaction.
文摘A new method of phase measurement based on optimization is presented. Simulations were ran with synthesized signals, and comparison was made with some spectral domain methods. The results show that, with a suitable number of samples processed, this method is superior to other methods in terms of accuracy, while the amplitude and phase of distortion component have no effect on accuracy.
文摘To recognize and measure the potential share value of conversion for convertible bonds more accurately,different approaches such as the straight method,the separating method,the expected value approach and the improved approach are comparatively analyzed by taking China Merchants Bank's convertible bonds as an example.There is also a focus on the improved approach that views that convertible bond issue proceeds can be separated into accrual debt value,accrual equity value and accrual option value according to the characteristics of debt,equity and hybrid securities with embedded options of convertible bonds.It is concluded that the improved approach is a more accurate evaluation method of capital structure so that it can fully reflect the economic reality of convertible bonds.
文摘This paper introduces a new approach for measuring shareholder value creation （called adjusted economic profit （EP）） which combines the advantages of both EP and APV （adjusted present value） methods. In particular, the shareholder value creation over a period is derived as the sum of two components： the EP relating purely to the operations of the company and the EP generated each period due to the tax benefit that arises from debt financing. We consider our results to be important for analysts and decision makers involved in appraising business performance or making investment decisions and HR professionals as well.
文摘There are many reasons whymerchant ships make desirable targetsfor pirates and terrorists as well as aconvenient means of transport for thestowaway. Criminal activity in the form ofsuch threats is quickly becoming one ofthe greatest threats to ships and
文摘In recent years, the college English teaching reform has been increasingly deepened. The study of the relationship between cognitive approach and foreign language teaching is undoubtedly instructive not only to guarantee the quality of foreign language teaching but also to improve learners＇ foreign language proficiency. In this essay, the author expounds the development of cognitive approach and some relative teaching principles, on which basis the author puts forward some specific practices in foreign language teaching.
基金supported by the National Key R&D Program of China (Grant Nos.2023YFA1406801 and 2022YFA1604301)the National Natural Science Foundation of China (Grant Nos.12434013,12595343,12404393,and 12174011)。
文摘High harmonic generation(HHG)provides an experimental method for producing attosecond pulses and probing electron dynamics.Achieving precise dipole phase measurements is critical for tailoring the harmonic emission phase and identifying the HHG mechanism.However,achieving this feature by applying traditional two-beam far-field interferometry to solid materials remains challenging.In this study,we present a novel interferometric approach that utilizes a single laser beam to excite two ZnO microwires(MWs)simultaneously,thereby generating coherent high-harmonic sources that form interference fringes in the far-field region.We leverage the diameter-dependent field-enhancement effect in MWs to measure the intensity-dependent fringe shift,revealing that the intraband current mechanism dominates the below-bandgap harmonic,whereas the interband polarization mechanism dominates the above-bandgap harmonic.This study offers a robust method for measuring the dipole phase of solid-state HHG and inspires intensity-modulated high-harmonic applications in coherent imaging and microdevice design.
基金co-supported by the National Natural Science Foundation of China(No.11602107)the Natural Science Foundation of Jiangsu Province of China(No.BK20150733)。
文摘A learning-based approach for solving wall shear stresses from Shear-Sensitive Liquid Crystal Coating(SSLCC) color images is presented in this paper. The approach is able to learn and establish the mapping relationship between the SSLCC color-change responses in different observation directions and the shear stress vectors, and then uses the mapping relationship to solve wall shear stress vectors from SSLCC color images. Experimental results show that the proposed approach can solve wall shear stress vectors using two or more SSLCC images, and even using only one image for symmetrical flow field. The accuracy of the approach using four or more observations is found to be comparable to that of the traditional multi-view Gauss curve fitting approach;the accuracy is slightly reduced when using two or fewer observations. The computational efficiency is significantly improved when compared with the traditional Gauss curve fitting approach, and the wall shear stress vectors can be solved in nearly real time. The learning-based approach has no strict requirements on illumination direction and observation directions and is therefore more flexible to use in practical wind tunnel measurement when compared with traditional liquid crystal-based methods.
基金supported by the National Natural Science Foundation of China(No.52272390)the Natural Science Foundation of Heilongjiang Province of China(No.YQ2022A009)the Shanghai Sailing Program,China(No.20YF1417300).
文摘Real-time 6 Degree-of-Freedom(DoF)pose estimation is of paramount importance for various on-orbit tasks.Benefiting from the development of deep learning,Convolutional Neural Networks(CNNs)in feature extraction has yielded impressive achievements for spacecraft pose estimation.To improve the robustness and interpretability of CNNs,this paper proposes a Pose Estimation approach based on Variational Auto-Encoder structure(PE-VAE)and a Feature-Aided pose estimation approach based on Variational Auto-Encoder structure(FA-VAE),which aim to accurately estimate the 6 DoF pose of a target spacecraft.Both methods treat the pose vector as latent variables,employing an encoder-decoder network with a Variational Auto-Encoder(VAE)structure.To enhance the precision of pose estimation,PE-VAE uses the VAE structure to introduce reconstruction mechanism with the whole image.Furthermore,FA-VAE enforces feature shape constraints by exclusively reconstructing the segment of the target spacecraft with the desired shape.Comparative evaluation against leading methods on public datasets reveals similar accuracy with a threefold improvement in processing speed,showcasing the significant contribution of VAE structures to accuracy enhancement,and the additional benefit of incorporating global shape prior features.
基金supported in part by the Natural Science Foundation of China(62003292,62203391)the Natural Science Foundation of Zhejiang Province(LQ22F030015,LDT23E05014F03)JSPS(Japan Society for the Promotion of Science)KAKENHI(22H03998,23K25252)。
文摘This paper presents a fixed-time equivalent-inputdisturbance(EID)approach to deal with the problem of robust output-feedback control for perturbed uncertain systems.This method uses the basic structure of the conventional EID approach and treats uncertainties and disturbances as a lumped disturbance on the control-input channel.A fixed-time state observer enables state estimation,which resolves the causality issue in an EID-based control system,is finished in a fixed time.An implicit Lyapunov function,the homogeneity with dilation,the input-tostate stability,and the small-gain theorem are used to analyze the convergence and robustness of the EID-based system with measurement noise.Numerical and experimental results are presented to demonstrate the effectiveness and superiority of the proposed method.
文摘Globally,human,livestock,and wildlife interactions have been reported to result in innumerable forms of conflict and consequences.The most notable consequences are on the environment and human health,among others.The least developed countries,Tanzania inclusive,due to their bio-geographical and social characteristics,are mostly reported to register such consequences,which have sometimes led to zoonotic diseases due to the existence of risk factors.The factors include the growth of the human population,absence of infrastructural capacity,and skilled manpower to effectively deal with disease outbreaks and livestock keeping associated lifestyles.This article employs a documentary research method to analyse the human-wildlife conflict(HWC)and its consequences in Tanzania.It further assesses the potential of the One Health approach to curb the consequences of HWC following the introduction of One Health Strategic Plan(2015–2020).This article,therefore,analyses the potential for One Health approach to minimize the undesirable impacts of human,livestock,and wildlife interactions on health.This approach underscores the need for collaborative working efforts involving human,livestock,wildlife,and environmental health professionals and the need for a good understanding of the consequences of the interactions towards the realisation of optimum health for people,animals,and our environment.
