The goal of this paper is to investigate the theory of Noether solvability for Volterra singular integral equations(VSIEs)with convolution and Cauchy kernels in a more general function class.To obtain the analytic sol...The goal of this paper is to investigate the theory of Noether solvability for Volterra singular integral equations(VSIEs)with convolution and Cauchy kernels in a more general function class.To obtain the analytic solutions,we transform such equations into boundary value problems with discontinuous coefficients by the properties of Fourier analysis.In view of the analytical Riemann-Hilbert method,the generalized Liouville theorem and Sokhotski-Plemelj formula,we get the uniqueness and existence of solutions for such problems,and study the asymptotic property of solutions at nodes.Therefore,this paper improves the theory of singular integral equations and boundary value problems.展开更多
In this note,the explicit form of the N soliton solutions for a class of the system of LS nonlinear wave interaction have been obtained by using Hirota's method.
As the key technology of extracting remote sensing information,the classification of remote sensing images has always been the research focus in the field of remote sensing. The paper introduces the classification pro...As the key technology of extracting remote sensing information,the classification of remote sensing images has always been the research focus in the field of remote sensing. The paper introduces the classification process and system of remote sensing images. According to the recent research status of domestic and international remote sensing classification methods,the new study dynamics of remote sensing classification,such as artificial neural networks,support vector machine,active learning and ensemble multi-classifiers,were introduced,providing references for the automatic and intelligent development of remote sensing images classification.展开更多
Music situational teaching method aims to mobilize the students’thoughts in a natural state so as to enhance the attractiveness and efficiency of music classes.In the process of this method,some specific situational ...Music situational teaching method aims to mobilize the students’thoughts in a natural state so as to enhance the attractiveness and efficiency of music classes.In the process of this method,some specific situational are designed according to the characteristics of music and under the guidance of psychology,methodology,pedagogy and other theories,and various sensory organs are employed.Different from traditional teaching method,situational teaching method creates learning situational for students,which is consistent with the characteristics of primary school students’physical and mental development and maximizes students’experience and feeling of music.展开更多
With the development of social civilization, people's spiritual pursuit is constantly changing and more and more attention is paid to education reform. It is very important to innovate the way of education and tea...With the development of social civilization, people's spiritual pursuit is constantly changing and more and more attention is paid to education reform. It is very important to innovate the way of education and teaching, to perfect the system of education and teaching and to dig the inner potential of students deeply, so as to cultivate a large number of high-quality talents, which is conducive to the new success of the modernization of society. During the period of secondary vocational education, it is the duty of the head teacher to continuously strengthen class management, care about students' study and life, and further enhance students' sense of ownership. This article specially from several aspects, on the teacher in charge of secondary vocational management of the class methods and skills were summarized and analyzed.展开更多
In order to explore the teaching method of junior high school physics exercise class under the new curriculum standard, and improve students' academic performance.In the early stage of this paper, we selected new ...In order to explore the teaching method of junior high school physics exercise class under the new curriculum standard, and improve students' academic performance.In the early stage of this paper, we selected new teaching methods through literature research. After screening and promoting several teaching methods, we determined the most appropriate teaching method through questionnaire.After the implementation of the teaching method, the students'liking degree of physics class has been significantly improved. The course mode that students like is more autonomous communication. More than 80% of the students can complete the teacher& apos;shomework on time. The problems encountered in the learning process are not waiting for the teacher's explanation, not searching for solutions on the Internet, but communicating with classmates to find appropriate explanation methods, and some of them will Think independently and find your own way.In the process of teaching reform, most students have learned to think and summarize. They can find the key points in class more clearly than before. They can review the wrong exercises many times and establish their own exercise set.After a period of research, it is found that compared with the traditional teaching mode, the new teaching mode is more diversified, which is more conducive to stimulate students'interest and enthusiasm, to cultivate students'subjective initiative to participate in physics exercise class, and to better develop students'autonomous learning potential.展开更多
Employing the two-state model and the time-dependent wave packet method, we have investigated the influences of the parameters of the intense femtosecond laser field on the evolution of the wave packet, as well as the...Employing the two-state model and the time-dependent wave packet method, we have investigated the influences of the parameters of the intense femtosecond laser field on the evolution of the wave packet, as well as the population of ground and double-minimum electronic states of the NaRb molecule. For the different laser wavelengths, the evolution of the wave packet of 6{ }^1／Sigma ^ ＋ state with time and internuclear distance is different, and the different laser intensity brings different influences on the population of the electronic states of the NaRb molecule. One can control the evolutions of wave packet and the population in each state by varying the laser parameters appropriately, which will be a benefit for the light manipulation of atomic and molecular processes.展开更多
The time-dependent wave packet method is used to investigate the influence of laser-fields on the vibrational population of molecules. For a two-state system in laser fields, the populations on different vibrational l...The time-dependent wave packet method is used to investigate the influence of laser-fields on the vibrational population of molecules. For a two-state system in laser fields, the populations on different vibrational levels of the upper and lower electronic states are given by wavefunctions obtained by solving the Schrbdinger equation with the split- operator method. The calculation shows that the field parameters, such as intensity, wavelength, duration, and delay time etc. can have different influences on the vibrational population. By varying the laser parameters appropriately one can control the evolution of wave packet and so the vibrational population in each state, which will benefit the light manipulation of atomic and molecular processes.展开更多
Light-induced conical intersections(LICIs)present a distinctive mechanism for nonadiabatic coupling,thereby facilitating ultrafast chemical reactions,including the indirect photodissociation of diatomic molecules.In c...Light-induced conical intersections(LICIs)present a distinctive mechanism for nonadiabatic coupling,thereby facilitating ultrafast chemical reactions,including the indirect photodissociation of diatomic molecules.In contrast to static conical intersections,LICIs are dynamically tunable,providing a pathway for precise control of molecular dissociation.In this study,we employ the time-dependent quantum wave packet method to investigate the dissociation dynamics of the OH molecule,focusing on its ground state X^(2)Πand repulsive state 1^(2)Σ~-.By varying laser field parameters(intensity,full width at half maximum(FWHM),and wavelength),we elucidate how nonadiabatic coupling governs selective dissociation channel control.Our findings reveal that the choice of initial vibrational states and the tailoring of laser conditions significantly influence dissociation pathways,providing theoretical insights into manipulating molecular dynamics via LICIs.These results provide a foundation for future experimental studies and the development of advanced molecular control techniques.展开更多
We present a fully time-dependent quantum wave packet evolution method for investigating molecular dynamics in intense laser fields.This approach enables the simultaneous treatment of interactions among multiple elect...We present a fully time-dependent quantum wave packet evolution method for investigating molecular dynamics in intense laser fields.This approach enables the simultaneous treatment of interactions among multiple electronic states while simultaneously tracking their time-dependent electronic,vibrational,and rotational dynamics.As an illustrative example,we consider neutral H_(2)molecules and simulate the laser-induced excitation dynamics of electronic and rotational states in strong laser fields,quantitatively distinguishing the respective contributions of electronic dipole transitions(within the classical-field approximation)and non-resonant Raman processes to the overall molecular dynamics.Furthermore,we precisely evaluate the relative contributions of direct tunneling ionization from the ground state and ionization following electronic excitation in the strong-field ionization of H_(2).The developed methodology shows strong potential for performing high-precision theoretical simulations of electronic-vibrational-rotational state excitations,ionization,and dissociation dynamics in molecules and their ions under intense laser fields.展开更多
For concrete situation of class teaching of landscape type of public elective course,the application situation of leading-subject teaching method in specific landscape type of course is explored. Teaching method trans...For concrete situation of class teaching of landscape type of public elective course,the application situation of leading-subject teaching method in specific landscape type of course is explored. Teaching method transforms from "teaching as the center" to "learning as the center". By improving student's learning interest and efficiency,student's whole development and creativity are promoted.展开更多
Due to unreliable and bandwidth-limited characteristics of communication link in networked control systems,the realtime compensated methods for single-output systems and multioutput systems are proposed in this paper ...Due to unreliable and bandwidth-limited characteristics of communication link in networked control systems,the realtime compensated methods for single-output systems and multioutput systems are proposed in this paper based on the compressed sensing(CS)theory and sliding window technique,by which the estimates of dropping data packets in the feedback channel are obtained and the performance degradation induced by packet drops is reduced.Specifically,in order to reduce the cumulative error caused by the algorithm,the compensated estimates for single-output systems are corrected via the regularization term;considering the process of single-packet transmission,a new sequential CS framework of sensor data streams is introduced to effectively compensate the dropping packet on single-channel of multi-output systems;in presence of the medium access constraints on multi-channel,the communication sequence for scheduling is coupled to the algorithm and the estimates of the multiple sensors for multi-output systems are obtained via the regularization term.Simulation results illustrate that the proposed methods perform well and receive satisfactory performance.展开更多
:Merchant ships,which are quite different from icebreakers,usually require the light ice-strengthened bow under the floe-ice condition.According to ice-class B,requirements of China Classification Society(CCS),interme...:Merchant ships,which are quite different from icebreakers,usually require the light ice-strengthened bow under the floe-ice condition.According to ice-class B,requirements of China Classification Society(CCS),intermediate frames and thick hull plates are necessary for the ice belt area to resist floe-ice impact.However,due to the limited space,it is not practical to set so many intermediate longitudinals from manufacture point of view.In this paper,a modification method is proposed to solve the problem by maintaining the frame spacing and increasing the plate thickness.The aim is to make sure that the bow owns the equivalent ice-bearing capacity with the original frame spacing.At first,a bulk carrier with ice-class B is used for case study.According to the requirements of the ice class rule,a designed ice thickness is used to calculate the ice load acting on the bow area due to the impact of ice floe.Two structural models are presented to perform the strength analysis under ice load,including the out-shell plate model and the longitudinal model.The results show that increasing the plate thickness is helpful to remove the negative effect induced by enlarging the spacing of the longitudinal.A reasonable curve is presented to modify the bow for the ice-strengthened merchant ship,which shows the relationship between the increase of plate thickness and the spacing of longitudinal.Moreover,a model test of floe-ice–ship interaction is conducted to measure the dynamic ice load,based on which nonlinear dynamic FE analysis is used to verify the presented plate-thickness–longitudinal spacing curve.The results show that the proposed method can be used to improve the ice-strengthened bow structure effectively,which provides theoretical foundation to modify the requirement of CCS’s ice class rule.展开更多
Although the classical spectral representation method(SRM)has been widely used in the generation of spatially varying ground motions,there are still challenges in efficient simulation of the non-stationary stochastic ...Although the classical spectral representation method(SRM)has been widely used in the generation of spatially varying ground motions,there are still challenges in efficient simulation of the non-stationary stochastic vector process in practice.The first problem is the inherent limitation and inflexibility of the deterministic time/frequency modulation function.Another difficulty is the estimation of evolutionary power spectral density(EPSD)with quite a few samples.To tackle these problems,the wavelet packet transform(WPT)algorithm is utilized to build a time-varying spectrum of seed recording which describes the energy distribution in the time-frequency domain.The time-varying spectrum is proven to preserve the time and frequency marginal property as theoretical EPSD will do for the stationary process.For the simulation of spatially varying ground motions,the auto-EPSD for all locations is directly estimated using the time-varying spectrum of seed recording rather than matching predefined EPSD models.Then the constructed spectral matrix is incorporated in SRM to simulate spatially varying non-stationary ground motions using efficient Cholesky decomposition techniques.In addition to a good match with the target coherency model,two numerical examples indicate that the generated time histories retain the physical properties of the prescribed seed recording,including waveform,temporal/spectral non-stationarity,normalized energy buildup,and significant duration.展开更多
Grain-size class-Std(GSCStd) and Grain-size class-dD(GSCdD) methods are simple statistical approaches for classifying bulk grain-size distributions(GSDs) into grain-size fractions. Although these two methods were deve...Grain-size class-Std(GSCStd) and Grain-size class-dD(GSCdD) methods are simple statistical approaches for classifying bulk grain-size distributions(GSDs) into grain-size fractions. Although these two methods were developed based on similar statistical principles, the classification difference between these two methods has not been analyzed. In this study, GSCStd and GSCdD methods are conducted in thirteen grain-size data sequences to examine the applicability for identifying grain size fractions. Results show that, application of the GSCStd method is equivalent to that of the GSCdD method in identifying finer grain-size fractions, and the difference between the two methods mainly comes from the identification of coarse grain-size fractions. Thus, finer grain-size fractions are recommended for use in research of surface aeolian and paleo-aeolian sediments. In addition, our results do not completely agree with previous studies, coarser grain-size fractions in our case suggest that the GSCdD method may not be more applicable than the GSCStd method.展开更多
The writers of the"red literary classics"replace the Confucian tradition of the blood relation with the modern"class struggle theory",so the class attribute becomes the one and only standard for va...The writers of the"red literary classics"replace the Confucian tradition of the blood relation with the modern"class struggle theory",so the class attribute becomes the one and only standard for value evaluation,under which the modern "class revolution"is quite different from the traditional blood revenge,taking on the expansion of the revenge object,the simplification of the revenge method,ennobling of the revenge motivation and the legalization of the revenge means and so on.展开更多
In order to promote the reform of vocational education,the state has issued the National Vocational Education Reform Implementation Plan,in which the reform of"Teachers,Teaching Materials,and Teaching Methods&quo...In order to promote the reform of vocational education,the state has issued the National Vocational Education Reform Implementation Plan,in which the reform of"Teachers,Teaching Materials,and Teaching Methods"as well as the"1+X"certificate have been the most prominent topics for discussion.Facing new opportunities for vocational education development,popularizing the blend of"1+x"courses and certificates,strengthening the integration of production and education,as well as enhancing professional soft skills are urgent issues to solved.This article combines the"1+X"certificate of civil engineering professional construction drawings and analyzes the necessity of promoting the"1+X"professional skill level as well as the combination of certificate and curriculum construction in deepening the reform of"Teachers,Teaching Materials,and Teaching Methods."Several suggestions have been put forward for the reform of"Teachers,Teaching Materials,and Teaching Methods"which would be helpful for the practical exploration in the reform of"three teaching methods."展开更多
Grammar-translation teaching method(GTTM as a shorthand below) has long been a buzzword when it is adopted in the class of English as a foreign language.It has been universally acknowledged that such teaching method c...Grammar-translation teaching method(GTTM as a shorthand below) has long been a buzzword when it is adopted in the class of English as a foreign language.It has been universally acknowledged that such teaching method contradicts the development of communicative language competence advocated in recent decades.However,I positively argue that GTTM in English class,as a comparative and intercultural model,should be given a due reconsideration to improve L2 learners' pragmatic competence.展开更多
Normalized Difference Vegetation Index （NDVI） is a very useful feature for differentiating vegetation and non-vegetation in remote sensed imagery. In the light of the function of NDVI and the spatial patterns of the...Normalized Difference Vegetation Index （NDVI） is a very useful feature for differentiating vegetation and non-vegetation in remote sensed imagery. In the light of the function of NDVI and the spatial patterns of the vegetation landscapes, we proposed the lacunarity texture derived from NDVI to characterize the spatial patterns of vegetation landscapes concerning the ＂gappiness＂ or ＂emptiness＂ characteristics. The NDVI-based lacunarity texture was incorporated into object-oriented classification for improving the identification of vegetation categories, especially Torreya which was the targeted tree species in the present research. A three-level hierarchical network of image objects was defined and the proposed texture was integrated as potential sources of information in the rules base. A knowledge base of rules created by classifier C5.0 indicated that the texture could potentially be applied in object-oriented classification. It was found that the addition of such texture improved the identification of every vegetation category. The results demonstrated that the texture could characterize the spatial patterns of vegetation structures, which could be a promising approach for vegetation identification.展开更多
This paper determines the exact error order on optimization of adaptive direct methods of approximate solution of the class of Fredholm integral equations of the second kind with kernel belonging to the anisotropic So...This paper determines the exact error order on optimization of adaptive direct methods of approximate solution of the class of Fredholm integral equations of the second kind with kernel belonging to the anisotropic Sobolev classes, and also gives an optimal algorithm.展开更多
基金Supported by National Natural Science Foundation of China(Grant No.11971015).
文摘The goal of this paper is to investigate the theory of Noether solvability for Volterra singular integral equations(VSIEs)with convolution and Cauchy kernels in a more general function class.To obtain the analytic solutions,we transform such equations into boundary value problems with discontinuous coefficients by the properties of Fourier analysis.In view of the analytical Riemann-Hilbert method,the generalized Liouville theorem and Sokhotski-Plemelj formula,we get the uniqueness and existence of solutions for such problems,and study the asymptotic property of solutions at nodes.Therefore,this paper improves the theory of singular integral equations and boundary value problems.
基金Project supported by the National Natural Science Foundation of China.
文摘In this note,the explicit form of the N soliton solutions for a class of the system of LS nonlinear wave interaction have been obtained by using Hirota's method.
基金Supported by the Science Research Foundation(2010Y290) of Yunnan Department of Education
文摘As the key technology of extracting remote sensing information,the classification of remote sensing images has always been the research focus in the field of remote sensing. The paper introduces the classification process and system of remote sensing images. According to the recent research status of domestic and international remote sensing classification methods,the new study dynamics of remote sensing classification,such as artificial neural networks,support vector machine,active learning and ensemble multi-classifiers,were introduced,providing references for the automatic and intelligent development of remote sensing images classification.
文摘Music situational teaching method aims to mobilize the students’thoughts in a natural state so as to enhance the attractiveness and efficiency of music classes.In the process of this method,some specific situational are designed according to the characteristics of music and under the guidance of psychology,methodology,pedagogy and other theories,and various sensory organs are employed.Different from traditional teaching method,situational teaching method creates learning situational for students,which is consistent with the characteristics of primary school students’physical and mental development and maximizes students’experience and feeling of music.
文摘With the development of social civilization, people's spiritual pursuit is constantly changing and more and more attention is paid to education reform. It is very important to innovate the way of education and teaching, to perfect the system of education and teaching and to dig the inner potential of students deeply, so as to cultivate a large number of high-quality talents, which is conducive to the new success of the modernization of society. During the period of secondary vocational education, it is the duty of the head teacher to continuously strengthen class management, care about students' study and life, and further enhance students' sense of ownership. This article specially from several aspects, on the teacher in charge of secondary vocational management of the class methods and skills were summarized and analyzed.
文摘In order to explore the teaching method of junior high school physics exercise class under the new curriculum standard, and improve students' academic performance.In the early stage of this paper, we selected new teaching methods through literature research. After screening and promoting several teaching methods, we determined the most appropriate teaching method through questionnaire.After the implementation of the teaching method, the students'liking degree of physics class has been significantly improved. The course mode that students like is more autonomous communication. More than 80% of the students can complete the teacher& apos;shomework on time. The problems encountered in the learning process are not waiting for the teacher's explanation, not searching for solutions on the Internet, but communicating with classmates to find appropriate explanation methods, and some of them will Think independently and find your own way.In the process of teaching reform, most students have learned to think and summarize. They can find the key points in class more clearly than before. They can review the wrong exercises many times and establish their own exercise set.After a period of research, it is found that compared with the traditional teaching mode, the new teaching mode is more diversified, which is more conducive to stimulate students'interest and enthusiasm, to cultivate students'subjective initiative to participate in physics exercise class, and to better develop students'autonomous learning potential.
基金supported by the National Natural Science Foundation of China (Grant Nos. 10674114 and 10604045)
文摘Employing the two-state model and the time-dependent wave packet method, we have investigated the influences of the parameters of the intense femtosecond laser field on the evolution of the wave packet, as well as the population of ground and double-minimum electronic states of the NaRb molecule. For the different laser wavelengths, the evolution of the wave packet of 6{ }^1／Sigma ^ ＋ state with time and internuclear distance is different, and the different laser intensity brings different influences on the population of the electronic states of the NaRb molecule. One can control the evolutions of wave packet and the population in each state by varying the laser parameters appropriately, which will be a benefit for the light manipulation of atomic and molecular processes.
基金Project supported by the Natural Science Foundation of Shandong Province of China (Grant No. Y2006A23)the National Basic Research Program of China (Grant No. 2006CB806000)the Open Fund of the State Key Laboratory of High Field Laser Physics (Shanghai Institute of Optics and Fine Mechanics)
文摘The time-dependent wave packet method is used to investigate the influence of laser-fields on the vibrational population of molecules. For a two-state system in laser fields, the populations on different vibrational levels of the upper and lower electronic states are given by wavefunctions obtained by solving the Schrbdinger equation with the split- operator method. The calculation shows that the field parameters, such as intensity, wavelength, duration, and delay time etc. can have different influences on the vibrational population. By varying the laser parameters appropriately one can control the evolution of wave packet and so the vibrational population in each state, which will benefit the light manipulation of atomic and molecular processes.
基金supported by the National Natural Science Foundation of China(Grant Nos.12134005 and 12334011)the Major Research Plan of the National Natural Science Foundation of China(Grant No.92461301)。
文摘Light-induced conical intersections(LICIs)present a distinctive mechanism for nonadiabatic coupling,thereby facilitating ultrafast chemical reactions,including the indirect photodissociation of diatomic molecules.In contrast to static conical intersections,LICIs are dynamically tunable,providing a pathway for precise control of molecular dissociation.In this study,we employ the time-dependent quantum wave packet method to investigate the dissociation dynamics of the OH molecule,focusing on its ground state X^(2)Πand repulsive state 1^(2)Σ~-.By varying laser field parameters(intensity,full width at half maximum(FWHM),and wavelength),we elucidate how nonadiabatic coupling governs selective dissociation channel control.Our findings reveal that the choice of initial vibrational states and the tailoring of laser conditions significantly influence dissociation pathways,providing theoretical insights into manipulating molecular dynamics via LICIs.These results provide a foundation for future experimental studies and the development of advanced molecular control techniques.
基金supported by the National Key Research and Development Program of China(Grant No.2022YFA1602502)the National Natural Science Foundation of China(Grant No.12450404)。
文摘We present a fully time-dependent quantum wave packet evolution method for investigating molecular dynamics in intense laser fields.This approach enables the simultaneous treatment of interactions among multiple electronic states while simultaneously tracking their time-dependent electronic,vibrational,and rotational dynamics.As an illustrative example,we consider neutral H_(2)molecules and simulate the laser-induced excitation dynamics of electronic and rotational states in strong laser fields,quantitatively distinguishing the respective contributions of electronic dipole transitions(within the classical-field approximation)and non-resonant Raman processes to the overall molecular dynamics.Furthermore,we precisely evaluate the relative contributions of direct tunneling ionization from the ground state and ionization following electronic excitation in the strong-field ionization of H_(2).The developed methodology shows strong potential for performing high-precision theoretical simulations of electronic-vibrational-rotational state excitations,ionization,and dissociation dynamics in molecules and their ions under intense laser fields.
基金Sponsored by Teaching Research and Reform Project of Undergraduate Education from Southwest Jiaotong University
文摘For concrete situation of class teaching of landscape type of public elective course,the application situation of leading-subject teaching method in specific landscape type of course is explored. Teaching method transforms from "teaching as the center" to "learning as the center". By improving student's learning interest and efficiency,student's whole development and creativity are promoted.
基金supported by the National Key Research and Development Plan(2018YFB1201601-12)。
文摘Due to unreliable and bandwidth-limited characteristics of communication link in networked control systems,the realtime compensated methods for single-output systems and multioutput systems are proposed in this paper based on the compressed sensing(CS)theory and sliding window technique,by which the estimates of dropping data packets in the feedback channel are obtained and the performance degradation induced by packet drops is reduced.Specifically,in order to reduce the cumulative error caused by the algorithm,the compensated estimates for single-output systems are corrected via the regularization term;considering the process of single-packet transmission,a new sequential CS framework of sensor data streams is introduced to effectively compensate the dropping packet on single-channel of multi-output systems;in presence of the medium access constraints on multi-channel,the communication sequence for scheduling is coupled to the algorithm and the estimates of the multiple sensors for multi-output systems are obtained via the regularization term.Simulation results illustrate that the proposed methods perform well and receive satisfactory performance.
基金the National Natural Science Foundation of China(No.51809124)the Jiangsu Natural Science Foundation Youth Project(No.BK20170576)the Research Foundation of State Key Laboratory of Ocean Engineering of Shanghai Jiao Tong University(Nos.1704 and 1807)。
文摘:Merchant ships,which are quite different from icebreakers,usually require the light ice-strengthened bow under the floe-ice condition.According to ice-class B,requirements of China Classification Society(CCS),intermediate frames and thick hull plates are necessary for the ice belt area to resist floe-ice impact.However,due to the limited space,it is not practical to set so many intermediate longitudinals from manufacture point of view.In this paper,a modification method is proposed to solve the problem by maintaining the frame spacing and increasing the plate thickness.The aim is to make sure that the bow owns the equivalent ice-bearing capacity with the original frame spacing.At first,a bulk carrier with ice-class B is used for case study.According to the requirements of the ice class rule,a designed ice thickness is used to calculate the ice load acting on the bow area due to the impact of ice floe.Two structural models are presented to perform the strength analysis under ice load,including the out-shell plate model and the longitudinal model.The results show that increasing the plate thickness is helpful to remove the negative effect induced by enlarging the spacing of the longitudinal.A reasonable curve is presented to modify the bow for the ice-strengthened merchant ship,which shows the relationship between the increase of plate thickness and the spacing of longitudinal.Moreover,a model test of floe-ice–ship interaction is conducted to measure the dynamic ice load,based on which nonlinear dynamic FE analysis is used to verify the presented plate-thickness–longitudinal spacing curve.The results show that the proposed method can be used to improve the ice-strengthened bow structure effectively,which provides theoretical foundation to modify the requirement of CCS’s ice class rule.
基金National Key Research and Development Program of China under Grant No.2023YFE0102900National Natural Science Foundation of China under Grant Nos.52378506 and 52208164。
文摘Although the classical spectral representation method(SRM)has been widely used in the generation of spatially varying ground motions,there are still challenges in efficient simulation of the non-stationary stochastic vector process in practice.The first problem is the inherent limitation and inflexibility of the deterministic time/frequency modulation function.Another difficulty is the estimation of evolutionary power spectral density(EPSD)with quite a few samples.To tackle these problems,the wavelet packet transform(WPT)algorithm is utilized to build a time-varying spectrum of seed recording which describes the energy distribution in the time-frequency domain.The time-varying spectrum is proven to preserve the time and frequency marginal property as theoretical EPSD will do for the stationary process.For the simulation of spatially varying ground motions,the auto-EPSD for all locations is directly estimated using the time-varying spectrum of seed recording rather than matching predefined EPSD models.Then the constructed spectral matrix is incorporated in SRM to simulate spatially varying non-stationary ground motions using efficient Cholesky decomposition techniques.In addition to a good match with the target coherency model,two numerical examples indicate that the generated time histories retain the physical properties of the prescribed seed recording,including waveform,temporal/spectral non-stationarity,normalized energy buildup,and significant duration.
基金supported by project funding from Chongqing Normal University (No. 12XLB009)Key Projects in the National Science & Technology Program (No. 2006BAD26B0302)
文摘Grain-size class-Std(GSCStd) and Grain-size class-dD(GSCdD) methods are simple statistical approaches for classifying bulk grain-size distributions(GSDs) into grain-size fractions. Although these two methods were developed based on similar statistical principles, the classification difference between these two methods has not been analyzed. In this study, GSCStd and GSCdD methods are conducted in thirteen grain-size data sequences to examine the applicability for identifying grain size fractions. Results show that, application of the GSCStd method is equivalent to that of the GSCdD method in identifying finer grain-size fractions, and the difference between the two methods mainly comes from the identification of coarse grain-size fractions. Thus, finer grain-size fractions are recommended for use in research of surface aeolian and paleo-aeolian sediments. In addition, our results do not completely agree with previous studies, coarser grain-size fractions in our case suggest that the GSCdD method may not be more applicable than the GSCStd method.
基金the staged achievement of the 54th fund project of China Postdoctoral Science Foundation--On the "Revolution/Revenge" Narration of the "Red Literary Classics" (2013M541491)
文摘The writers of the"red literary classics"replace the Confucian tradition of the blood relation with the modern"class struggle theory",so the class attribute becomes the one and only standard for value evaluation,under which the modern "class revolution"is quite different from the traditional blood revenge,taking on the expansion of the revenge object,the simplification of the revenge method,ennobling of the revenge motivation and the legalization of the revenge means and so on.
文摘In order to promote the reform of vocational education,the state has issued the National Vocational Education Reform Implementation Plan,in which the reform of"Teachers,Teaching Materials,and Teaching Methods"as well as the"1+X"certificate have been the most prominent topics for discussion.Facing new opportunities for vocational education development,popularizing the blend of"1+x"courses and certificates,strengthening the integration of production and education,as well as enhancing professional soft skills are urgent issues to solved.This article combines the"1+X"certificate of civil engineering professional construction drawings and analyzes the necessity of promoting the"1+X"professional skill level as well as the combination of certificate and curriculum construction in deepening the reform of"Teachers,Teaching Materials,and Teaching Methods."Several suggestions have been put forward for the reform of"Teachers,Teaching Materials,and Teaching Methods"which would be helpful for the practical exploration in the reform of"three teaching methods."
文摘Grammar-translation teaching method(GTTM as a shorthand below) has long been a buzzword when it is adopted in the class of English as a foreign language.It has been universally acknowledged that such teaching method contradicts the development of communicative language competence advocated in recent decades.However,I positively argue that GTTM in English class,as a comparative and intercultural model,should be given a due reconsideration to improve L2 learners' pragmatic competence.
基金supported by the National Natural Science Foundation of China (30671212)
文摘Normalized Difference Vegetation Index （NDVI） is a very useful feature for differentiating vegetation and non-vegetation in remote sensed imagery. In the light of the function of NDVI and the spatial patterns of the vegetation landscapes, we proposed the lacunarity texture derived from NDVI to characterize the spatial patterns of vegetation landscapes concerning the ＂gappiness＂ or ＂emptiness＂ characteristics. The NDVI-based lacunarity texture was incorporated into object-oriented classification for improving the identification of vegetation categories, especially Torreya which was the targeted tree species in the present research. A three-level hierarchical network of image objects was defined and the proposed texture was integrated as potential sources of information in the rules base. A knowledge base of rules created by classifier C5.0 indicated that the texture could potentially be applied in object-oriented classification. It was found that the addition of such texture improved the identification of every vegetation category. The results demonstrated that the texture could characterize the spatial patterns of vegetation structures, which could be a promising approach for vegetation identification.
基金Project supported by the Natural Science Foundation of China(10371009)Research Fund for the Doctoral Program Higher Education
文摘This paper determines the exact error order on optimization of adaptive direct methods of approximate solution of the class of Fredholm integral equations of the second kind with kernel belonging to the anisotropic Sobolev classes, and also gives an optimal algorithm.
