Experimental and theoretical studies of drag embedment plate anchors recently carried out in Tianjin University are summarized in this research paper, which involve a series of important topics relevant to the study o...Experimental and theoretical studies of drag embedment plate anchors recently carried out in Tianjin University are summarized in this research paper, which involve a series of important topics relevant to the study of drag anchors. The techniques for measuring the trajectory and movement direction of drag anchors in soils, the techniques for measuring the moving embedment point and reverse eatenary shape of the embedded drag line, the penetration mechanism and kinematic behavior of drag anchors, the ultimate embedment depth of drag anchors, the movement direction of the anchor with an arbitrary fluke section, the reverse catenary properties of the embedded drag line, the interaetional properties between drag anchor and installation line, the kinematic model of drag anchors in seabed soils, and the analytical method for predicting the anchor trajectory in soils will all be examined. The present work remarkably reduces the uncertainties in design and analysis of drag embedment plate anchors, and is beneficial to improving the application of this new type of drag anchor in offshore engineering.展开更多
Most research on anomaly detection has focused on event that is different from its spatial-temporal neighboring events.It is still a significant challenge to detect anomalies that involve multiple normal events intera...Most research on anomaly detection has focused on event that is different from its spatial-temporal neighboring events.It is still a significant challenge to detect anomalies that involve multiple normal events interacting in an unusual pattern.In this work,a novel unsupervised method based on sparse topic model was proposed to capture motion patterns and detect anomalies in traffic surveillance.scale-invariant feature transform(SIFT)flow was used to improve the dense trajectory in order to extract interest points and the corresponding descriptors with less interference.For the purpose of strengthening the relationship of interest points on the same trajectory,the fisher kernel method was applied to obtain the representation of trajectory which was quantized into visual word.Then the sparse topic model was proposed to explore the latent motion patterns and achieve a sparse representation for the video scene.Finally,two anomaly detection algorithms were compared based on video clip detection and visual word analysis respectively.Experiments were conducted on QMUL Junction dataset and AVSS dataset.The results demonstrated the superior efficiency of the proposed method.展开更多
This paper focuses on the research of a semi-submersible platform equipped with a DP-assisted mooring system. Based on the working principles of the DP-assisted mooring system and the model of the platform motion, a t...This paper focuses on the research of a semi-submersible platform equipped with a DP-assisted mooring system. Based on the working principles of the DP-assisted mooring system and the model of the platform motion, a time domain simulation program is applied to analyze the impact, in the case of one line failure, on the platform motion, power consumption of the thrusters and the tension of the mooring lines. The results show that, under the 10-year wind dominant, a one line failure will have little impact on the tension of the mooring lines. When the failure line is windward, the power consumption will increase greatly with a weakened position of accuracy. However when the failure line is leeward, the power consumption will be reduced with a partly strengthened oosition of accuracy.展开更多
In this paper, firstly, we get the Hojman exact invariants by Lie symmetry for an undisturbed generalized Raitzin equation of motion. Secondly, we study the perturbation to Lie symmetry of generalized Raitzin canonica...In this paper, firstly, we get the Hojman exact invariants by Lie symmetry for an undisturbed generalized Raitzin equation of motion. Secondly, we study the perturbation to Lie symmetry of generalized Raitzin canonical equation of motion and get Hojman adiabatic invariants. Lastly, an example is given to illustrate the application of the results.展开更多
Loads generated after an air crash, ship collision, and other accidents may destroy very large floating structures （VLFSs） and create additional connector loads. In this study, the combined effects of ship collision...Loads generated after an air crash, ship collision, and other accidents may destroy very large floating structures （VLFSs） and create additional connector loads. In this study, the combined effects of ship collision and wave loads are considered to establish motion differential equations for a multi-body VLFS. A time domain calculation method is proposed to calculate the connector load of the VLFS in waves. The Longuet-Higgins model is employed to simulate the stochastic wave load. Fluid force and hydrodynamic coefficient are obtained with DNV Sesam software. The motion differential equation is calculated by applying the time domain method when the frequency domain hydrodynamic coefficient is converted into the memory function of the motion differential equation of the time domain. As a result of the combined action of wave and impact loads, high-frequency oscillation is observed in the time history curve of the connector load. At wave directions of 0° and 75°, the regularities of the time history curves of the connector loads in different directions are similar and the connector loads of C1 and C2 in the X direction are the largest. The oscillation load is observed in the connector in the Y direction at a wave direction of 75° and not at 0° This paper presents a time domain calculation method of connector load to provide a certain reference function for the future development of Chinese VLFS展开更多
An extended π calculus was introduced to deal with secure movement and intercommunication between agents. The system extends Nomadic-π with objective migration primitive and confined region which serves as annotatio...An extended π calculus was introduced to deal with secure movement and intercommunication between agents. The system extends Nomadic-π with objective migration primitive and confined region which serves as annotation labels of agents and channels. The confined region labels were used to uniquely identify the constraints on the migration and communication of agents, with the labels, the agents could be confined in a secure subsystem and the inter-agent communication could be confined between agents located on trusted sites during computation. The operational semantics for the calculus was given out, and a type system which enforces security properties called confined migration and confined communication was developed.展开更多
We give a study on the general Moiler transformation and emphatically introduce its differential form. In this paper, a definition of acceleration is given in spacetime language and the inertial reference frame is als...We give a study on the general Moiler transformation and emphatically introduce its differential form. In this paper, a definition of acceleration is given in spacetime language and the inertial reference frame is also settled. With a discussion of the geodesic equations of motion, the differential form of the general MФller transformation at arbitrary direction is presented.展开更多
A novel continuum robot for colonoscopy is presented.The aim is to develop a robot for colonoscopywhich can provide the same functions as conventional colonoscope,but much less pain and discomfort forpatient.In contra...A novel continuum robot for colonoscopy is presented.The aim is to develop a robot for colonoscopywhich can provide the same functions as conventional colonoscope,but much less pain and discomfort forpatient.In contrast to traditional rigid-link robot,the robot features a continuous backbone with nojoints.The continuum robot is 300 mm in total length and 12 mm in diameter that is less than the averagediameter of human colon(20 mm).The robot has a total of 4 DOF(degrees of freedom)and is actuatedremotely by 6 hybrid step motors through super-elastic NiTi wires.Its shape can be changed with highdexterity,therefore ensuring its adaptability to the tortuous shape of human colon.The mechanical struc-ture,kinematics and DSP-based control system are discussed; prototype experiments are carried out tovalidate the kinematics model and to show the motion performances.展开更多
The empirical study shows that the return rate of the stock price has a long memory, which can be described by fractal Brown motion. The fact that fractal Brown motion does not have the characteristics of Markov makes...The empirical study shows that the return rate of the stock price has a long memory, which can be described by fractal Brown motion. The fact that fractal Brown motion does not have the characteristics of Markov makes the American option value depends on the price change path of the underlying asset. And the ordinary American option pricing model underestimates the American option value. In order to fully reflect the long memory of the underlying asset return rates, we propose fractal American option pricing model, fractal Bermuda option pricing model, and a fractal combination of American option pricing model. Fractal American option value is greater than the ordinary American option value.展开更多
The steric mass-action (SMA) model has been widely reported in the literature for ion-exchange and metal-affinity interaction adsorption equilibrium of biomacromolecules. In this paper, the usefulness of SMA model is ...The steric mass-action (SMA) model has been widely reported in the literature for ion-exchange and metal-affinity interaction adsorption equilibrium of biomacromolecules. In this paper, the usefulness of SMA model is analyzed for describing micromolecule ion-exchange equilibrium onto cation exchangers, CM Sephadex C-25 and Streamline SP. Batch adsorption experiments with ephedrine hydrochloride as a model adsorbate are carried out to determine the model parameters, that is, steric factor, characteristic charge and equilibrium constant. The result shows that the SMA model parameters of micromolecule cannot be obtained using the nonlinear least-square fitting method as protein's due to the remarkable difference between the molecular mass and dimension of micromolecule and protein. It is considered that the small size of the adsorbates dealt with in this study justifies the neglect of steric hindrances arising from adsorbate bulkiness. Thus, the three-parameter SMA model is reduced to two-parameter one (i.e., steric factor is equal to zero) for describing micromolecule ion-exchange equilibrium. It is found that the equilibrium constant for CM Sephadex C-25 increases with increasing ionic strength, while the equilibrium constant for Streamline SP shows an opposite trend. This is probably due to the remarkable difference between the physicalpro perties of the two adsorbents. Then, the relationship between the equilibrium constant and ionic strength is described by an expression. The computer simulations show that, the theoretical model with the correlation is promising in the prediction of micromolecule adsorption decrease with increasing ionic strength in a wide range of salt concentration.展开更多
The motion＇s generation consists in finding an analytic expression of a motion according to time. A Map road type planner or Cell decomposition provide to the motion generator some possible free crossing points of co...The motion＇s generation consists in finding an analytic expression of a motion according to time. A Map road type planner or Cell decomposition provide to the motion generator some possible free crossing points of collision. The global trajectory＇s interpolation by a polynomial is generally not possible, because the degree of the polynomial increases with the number of crossing points which can generate vibrations or loops of the. trajectory. The solution consists in using polynomials in an inferior degree and to build the motion in pieces. The theoretical developments concern the motion＇s generation, the modeling of the vehicle, then the management of its redundancy steam-power. All these methods contribute to improve the robot precision （accuracy）. The authors are presenting the motion＇s generator which constructs into lines a continuous trajectory C2 while enabling the transformation of the crossing points into lines. The generator presented here as part of omnidirectional robot is adaptable to any kind of vehicle.展开更多
Understanding the movement of animals is fundamental to population and community ecology. Historically, it has been difficult to quantify movement patterns of most fishes, but technological advances in acoustic teleme...Understanding the movement of animals is fundamental to population and community ecology. Historically, it has been difficult to quantify movement patterns of most fishes, but technological advances in acoustic telemetry have increased our abilities to monitor their movement. In this study, we combined small-scale active acoustic tracking with large-scale passive acoustic monitoring to develop an empirical movement model for sixgill sharks in Puget Sound, WA, USA. We began by testing whether a correlated random walk model described the daily movement of sixgills; however, the model failed to capture home-ranging behavior. We added this behavior and used the resultant model （a biased random walk model） to determine whether daily movement patterns are able to explain large-scale seasonal movement. The daily model did not explain the larger-scale pat- terns of movement observed in the passive monitoring data. In order to create the large-scale patterns, sixgills must have per- formed behaviors （large, fast directed movements） that were unobserved during small-scale active tracking. In addition, seasonal shifts in location were not captured by the dally model. We added these ＇unobserved＇ behaviors to the model and were able to capture large-scale seasonal movement of sixgill sharks over 150 days. The development of empirical models of movement al- lows researchers to develop hypotheses and test mechanisms responsible for a species movement behavior and spatial distribution. This knowledge will increase our ability to successfully manage species of concern [Current Zoology 58 （1）： 103-115, 2012].展开更多
基金Foundation item： Supported by the National Natural Science Foundation of China （Grant nos. 50639030 and 50979070） and the 863 Program of China （Grant no. 2006AA09Z348）.
文摘Experimental and theoretical studies of drag embedment plate anchors recently carried out in Tianjin University are summarized in this research paper, which involve a series of important topics relevant to the study of drag anchors. The techniques for measuring the trajectory and movement direction of drag anchors in soils, the techniques for measuring the moving embedment point and reverse eatenary shape of the embedded drag line, the penetration mechanism and kinematic behavior of drag anchors, the ultimate embedment depth of drag anchors, the movement direction of the anchor with an arbitrary fluke section, the reverse catenary properties of the embedded drag line, the interaetional properties between drag anchor and installation line, the kinematic model of drag anchors in seabed soils, and the analytical method for predicting the anchor trajectory in soils will all be examined. The present work remarkably reduces the uncertainties in design and analysis of drag embedment plate anchors, and is beneficial to improving the application of this new type of drag anchor in offshore engineering.
基金Project(50808025)supported by the National Natural Science Foundation of ChinaProject(20090162110057)supported by the Doctoral Fund of Ministry of Education,China
文摘Most research on anomaly detection has focused on event that is different from its spatial-temporal neighboring events.It is still a significant challenge to detect anomalies that involve multiple normal events interacting in an unusual pattern.In this work,a novel unsupervised method based on sparse topic model was proposed to capture motion patterns and detect anomalies in traffic surveillance.scale-invariant feature transform(SIFT)flow was used to improve the dense trajectory in order to extract interest points and the corresponding descriptors with less interference.For the purpose of strengthening the relationship of interest points on the same trajectory,the fisher kernel method was applied to obtain the representation of trajectory which was quantized into visual word.Then the sparse topic model was proposed to explore the latent motion patterns and achieve a sparse representation for the video scene.Finally,two anomaly detection algorithms were compared based on video clip detection and visual word analysis respectively.Experiments were conducted on QMUL Junction dataset and AVSS dataset.The results demonstrated the superior efficiency of the proposed method.
基金Suppirted by the Programme of Introducing Talents of Discipline to Universities(B07019)
文摘This paper focuses on the research of a semi-submersible platform equipped with a DP-assisted mooring system. Based on the working principles of the DP-assisted mooring system and the model of the platform motion, a time domain simulation program is applied to analyze the impact, in the case of one line failure, on the platform motion, power consumption of the thrusters and the tension of the mooring lines. The results show that, under the 10-year wind dominant, a one line failure will have little impact on the tension of the mooring lines. When the failure line is windward, the power consumption will increase greatly with a weakened position of accuracy. However when the failure line is leeward, the power consumption will be reduced with a partly strengthened oosition of accuracy.
文摘In this paper, firstly, we get the Hojman exact invariants by Lie symmetry for an undisturbed generalized Raitzin equation of motion. Secondly, we study the perturbation to Lie symmetry of generalized Raitzin canonical equation of motion and get Hojman adiabatic invariants. Lastly, an example is given to illustrate the application of the results.
基金Foundation item： Supported by the National Natural Science Foundation of China （51309123）, National Key Basic Research and Development Plan （973 Plan, 2013CB036104）, Jiangsu Province Natural Science Research Projects in Colleges and Universities （13KJB570002）, Open Foundation of State Key Laboratory of Ocean Engineering （1407）, ＂Qing Lan Project＂ of Colleges and Universities in Jiangsu Province, Academic Program Development of Jiangsu Higher Education Institutions （PAPD）.
文摘Loads generated after an air crash, ship collision, and other accidents may destroy very large floating structures （VLFSs） and create additional connector loads. In this study, the combined effects of ship collision and wave loads are considered to establish motion differential equations for a multi-body VLFS. A time domain calculation method is proposed to calculate the connector load of the VLFS in waves. The Longuet-Higgins model is employed to simulate the stochastic wave load. Fluid force and hydrodynamic coefficient are obtained with DNV Sesam software. The motion differential equation is calculated by applying the time domain method when the frequency domain hydrodynamic coefficient is converted into the memory function of the motion differential equation of the time domain. As a result of the combined action of wave and impact loads, high-frequency oscillation is observed in the time history curve of the connector load. At wave directions of 0° and 75°, the regularities of the time history curves of the connector loads in different directions are similar and the connector loads of C1 and C2 in the X direction are the largest. The oscillation load is observed in the connector in the Y direction at a wave direction of 75° and not at 0° This paper presents a time domain calculation method of connector load to provide a certain reference function for the future development of Chinese VLFS
基金The National Defense Project of China(No417010602)
文摘An extended π calculus was introduced to deal with secure movement and intercommunication between agents. The system extends Nomadic-π with objective migration primitive and confined region which serves as annotation labels of agents and channels. The confined region labels were used to uniquely identify the constraints on the migration and communication of agents, with the labels, the agents could be confined in a secure subsystem and the inter-agent communication could be confined between agents located on trusted sites during computation. The operational semantics for the calculus was given out, and a type system which enforces security properties called confined migration and confined communication was developed.
文摘We give a study on the general Moiler transformation and emphatically introduce its differential form. In this paper, a definition of acceleration is given in spacetime language and the inertial reference frame is also settled. With a discussion of the geodesic equations of motion, the differential form of the general MФller transformation at arbitrary direction is presented.
基金Supported by the High Technology Research Development Programme of China (No. 2007AA042105)the Program for Changjiang Scholars and Innovative Research Team in University (IRT0423)
文摘A novel continuum robot for colonoscopy is presented.The aim is to develop a robot for colonoscopywhich can provide the same functions as conventional colonoscope,but much less pain and discomfort forpatient.In contrast to traditional rigid-link robot,the robot features a continuous backbone with nojoints.The continuum robot is 300 mm in total length and 12 mm in diameter that is less than the averagediameter of human colon(20 mm).The robot has a total of 4 DOF(degrees of freedom)and is actuatedremotely by 6 hybrid step motors through super-elastic NiTi wires.Its shape can be changed with highdexterity,therefore ensuring its adaptability to the tortuous shape of human colon.The mechanical struc-ture,kinematics and DSP-based control system are discussed; prototype experiments are carried out tovalidate the kinematics model and to show the motion performances.
文摘The empirical study shows that the return rate of the stock price has a long memory, which can be described by fractal Brown motion. The fact that fractal Brown motion does not have the characteristics of Markov makes the American option value depends on the price change path of the underlying asset. And the ordinary American option pricing model underestimates the American option value. In order to fully reflect the long memory of the underlying asset return rates, we propose fractal American option pricing model, fractal Bermuda option pricing model, and a fractal combination of American option pricing model. Fractal American option value is greater than the ordinary American option value.
文摘The steric mass-action (SMA) model has been widely reported in the literature for ion-exchange and metal-affinity interaction adsorption equilibrium of biomacromolecules. In this paper, the usefulness of SMA model is analyzed for describing micromolecule ion-exchange equilibrium onto cation exchangers, CM Sephadex C-25 and Streamline SP. Batch adsorption experiments with ephedrine hydrochloride as a model adsorbate are carried out to determine the model parameters, that is, steric factor, characteristic charge and equilibrium constant. The result shows that the SMA model parameters of micromolecule cannot be obtained using the nonlinear least-square fitting method as protein's due to the remarkable difference between the molecular mass and dimension of micromolecule and protein. It is considered that the small size of the adsorbates dealt with in this study justifies the neglect of steric hindrances arising from adsorbate bulkiness. Thus, the three-parameter SMA model is reduced to two-parameter one (i.e., steric factor is equal to zero) for describing micromolecule ion-exchange equilibrium. It is found that the equilibrium constant for CM Sephadex C-25 increases with increasing ionic strength, while the equilibrium constant for Streamline SP shows an opposite trend. This is probably due to the remarkable difference between the physicalpro perties of the two adsorbents. Then, the relationship between the equilibrium constant and ionic strength is described by an expression. The computer simulations show that, the theoretical model with the correlation is promising in the prediction of micromolecule adsorption decrease with increasing ionic strength in a wide range of salt concentration.
文摘The motion＇s generation consists in finding an analytic expression of a motion according to time. A Map road type planner or Cell decomposition provide to the motion generator some possible free crossing points of collision. The global trajectory＇s interpolation by a polynomial is generally not possible, because the degree of the polynomial increases with the number of crossing points which can generate vibrations or loops of the. trajectory. The solution consists in using polynomials in an inferior degree and to build the motion in pieces. The theoretical developments concern the motion＇s generation, the modeling of the vehicle, then the management of its redundancy steam-power. All these methods contribute to improve the robot precision （accuracy）. The authors are presenting the motion＇s generator which constructs into lines a continuous trajectory C2 while enabling the transformation of the crossing points into lines. The generator presented here as part of omnidirectional robot is adaptable to any kind of vehicle.
文摘Understanding the movement of animals is fundamental to population and community ecology. Historically, it has been difficult to quantify movement patterns of most fishes, but technological advances in acoustic telemetry have increased our abilities to monitor their movement. In this study, we combined small-scale active acoustic tracking with large-scale passive acoustic monitoring to develop an empirical movement model for sixgill sharks in Puget Sound, WA, USA. We began by testing whether a correlated random walk model described the daily movement of sixgills; however, the model failed to capture home-ranging behavior. We added this behavior and used the resultant model （a biased random walk model） to determine whether daily movement patterns are able to explain large-scale seasonal movement. The daily model did not explain the larger-scale pat- terns of movement observed in the passive monitoring data. In order to create the large-scale patterns, sixgills must have per- formed behaviors （large, fast directed movements） that were unobserved during small-scale active tracking. In addition, seasonal shifts in location were not captured by the dally model. We added these ＇unobserved＇ behaviors to the model and were able to capture large-scale seasonal movement of sixgill sharks over 150 days. The development of empirical models of movement al- lows researchers to develop hypotheses and test mechanisms responsible for a species movement behavior and spatial distribution. This knowledge will increase our ability to successfully manage species of concern [Current Zoology 58 （1）： 103-115, 2012].
