For natural images with complex background and noise, this new approach appears is more effective than other techniques for three key reasons: 1)edge elements treated interdependently to overcome the weakness of stand...For natural images with complex background and noise, this new approach appears is more effective than other techniques for three key reasons: 1)edge elements treated interdependently to overcome the weakness of standard Hough transform (HT); 2)gradient orientation information taken into account in the process of HT; 3) an effective method used to "merge" the HT result, i.e. many "clustered short lines" into single straight line to represent the edge of object to be recognized. This method consists of three steps are: 1) edge detection; 2)modified Hough transform to extract "clustered short lines"; 3) merging "clustered short lines" into a single line after few modifications. The method presented in this paper could also be used for extraction of non vertical straight lines.展开更多
For a 2-station and 3-class reentrant line under first-buffer first-served(FBFS)service discipline in light traffic,we firstly construct the strong approximations for performance measures including the queue length,wo...For a 2-station and 3-class reentrant line under first-buffer first-served(FBFS)service discipline in light traffic,we firstly construct the strong approximations for performance measures including the queue length,workload,busy time and idle time processes.Based on the obtained strong approximations,we use a strong approximation method to find all the law of the iterated logarithms(LILs)for the above four performance measures,which are expressed as some functions of system parameters:means and variances of interarrival and service times,and characterize the fluctuations around their fluid approximations.展开更多
In this study, the method of lines (MOLs) with higher order central difference approximation method coupled with the classical fourth order Runge-Kutta (RK(4,4)) method is used in solving shallow water equations (SWEs...In this study, the method of lines (MOLs) with higher order central difference approximation method coupled with the classical fourth order Runge-Kutta (RK(4,4)) method is used in solving shallow water equations (SWEs) in Cartesian coordinates to foresee water levels associated with a storm accurately along the coast of Bangladesh. In doing so, the partial derivatives of the SWEs with respect to the space variables were discretized with 5-point central difference, as a test case, to obtain a system of ordinary differential equations with time as an independent variable for every spatial grid point, which with initial conditions were solved by the RK(4,4) method. The complex land-sea interface and bottom topographic details were incorporated closely using nested schemes. The coastal and island boundaries were rectangularized through proper stair step representation, and the storing positions of the scalar and momentum variables were specified according to the rules of structured C-grid. A stable tidal regime was made over the model domain considering the effect of the major tidal constituent, M2 along the southern open boundary of the outermost parent scheme. The Meghna River fresh water discharge was taken into account for the inner most child scheme. To take into account the dynamic interaction of tide and surge, the generated tidal regime was introduced as the initial state of the sea, and the surge was then made to come over it through computer simulation. Numerical experiments were performed with the cyclone April 1991 to simulate water levels due to tide, surge, and their interaction at different stations along the coast of Bangladesh. Our computed results were found to compare reasonable well with the limited observed data obtained from Bangladesh Inland Water Transport Authority (BIWTA) and were found to be better in comparison with the results obtained through the regular finite difference method and the 3-point central difference MOLs coupled with the RK(4,4) method with regard to the root mean square error values.展开更多
An algorithm for approximating arbitrary NURBS curve with straight line is presented.Firstly,NURBS curve is acquired according to data points on the curve.Secondly,Approximating arbitrary NURBS curve is based on dicho...An algorithm for approximating arbitrary NURBS curve with straight line is presented.Firstly,NURBS curve is acquired according to data points on the curve.Secondly,Approximating arbitrary NURBS curve is based on dichotomy.The resulting straight line approaches to the original curve with relatively fewer segments within the required tolerance.The example shows that the algorithm is simple and its approximation precision is high.The method is most useful in numerical control to drive the cutter along straight line or circular paths.展开更多
The theory of RC uniform ladder networks based upon the recurrence of voltage and cur-rent functions is extended as a vehicle to analyse the dynamic characteristics of reg lines. Meth-ods for computing the time consta...The theory of RC uniform ladder networks based upon the recurrence of voltage and cur-rent functions is extended as a vehicle to analyse the dynamic characteristics of reg lines. Meth-ods for computing the time constants and simplifying the transfer functions for reg lines are alsopresented.展开更多
The structure and microstructure of constituent phases in annealed IQC100-xDQCx alloys, made from mixtures of (Al62Cu25.5Fe12.5) icosahedral quasicrystal （IQC） and (Al70Co15Ni15) decagonal quasicrystal （DQC）, were...The structure and microstructure of constituent phases in annealed IQC100-xDQCx alloys, made from mixtures of (Al62Cu25.5Fe12.5) icosahedral quasicrystal （IQC） and (Al70Co15Ni15) decagonal quasicrystal （DQC）, were studied by X-ray diffractometry（XRD）, scanning electron microscopy （SEM）, and energy-dispersive X-ray spectroscopy （EDAX）. These constituent phases are mostly approximants: λ, β and τ3. In addition, an Al-Cu-Co DQC phase is observed in (IQC80DQC20) alloy. The nature of these approximants and their relationship with the quasicrystals（QCs） are discussed; and the evolution of these phases is interpreted by the shifting of their e/a-constant lines in the Al-（Cu, Ni）-（Fe, Co） pseudo-ternary phase diagrams.展开更多
文摘For natural images with complex background and noise, this new approach appears is more effective than other techniques for three key reasons: 1)edge elements treated interdependently to overcome the weakness of standard Hough transform (HT); 2)gradient orientation information taken into account in the process of HT; 3) an effective method used to "merge" the HT result, i.e. many "clustered short lines" into single straight line to represent the edge of object to be recognized. This method consists of three steps are: 1) edge detection; 2)modified Hough transform to extract "clustered short lines"; 3) merging "clustered short lines" into a single line after few modifications. The method presented in this paper could also be used for extraction of non vertical straight lines.
基金supported by the National Natural Science Foundation of China(No.11871116 and No.11971074)by the Fundamental Research Funds for the Central Universities(No.2023ZCJH02)。
文摘For a 2-station and 3-class reentrant line under first-buffer first-served(FBFS)service discipline in light traffic,we firstly construct the strong approximations for performance measures including the queue length,workload,busy time and idle time processes.Based on the obtained strong approximations,we use a strong approximation method to find all the law of the iterated logarithms(LILs)for the above four performance measures,which are expressed as some functions of system parameters:means and variances of interarrival and service times,and characterize the fluctuations around their fluid approximations.
文摘In this study, the method of lines (MOLs) with higher order central difference approximation method coupled with the classical fourth order Runge-Kutta (RK(4,4)) method is used in solving shallow water equations (SWEs) in Cartesian coordinates to foresee water levels associated with a storm accurately along the coast of Bangladesh. In doing so, the partial derivatives of the SWEs with respect to the space variables were discretized with 5-point central difference, as a test case, to obtain a system of ordinary differential equations with time as an independent variable for every spatial grid point, which with initial conditions were solved by the RK(4,4) method. The complex land-sea interface and bottom topographic details were incorporated closely using nested schemes. The coastal and island boundaries were rectangularized through proper stair step representation, and the storing positions of the scalar and momentum variables were specified according to the rules of structured C-grid. A stable tidal regime was made over the model domain considering the effect of the major tidal constituent, M2 along the southern open boundary of the outermost parent scheme. The Meghna River fresh water discharge was taken into account for the inner most child scheme. To take into account the dynamic interaction of tide and surge, the generated tidal regime was introduced as the initial state of the sea, and the surge was then made to come over it through computer simulation. Numerical experiments were performed with the cyclone April 1991 to simulate water levels due to tide, surge, and their interaction at different stations along the coast of Bangladesh. Our computed results were found to compare reasonable well with the limited observed data obtained from Bangladesh Inland Water Transport Authority (BIWTA) and were found to be better in comparison with the results obtained through the regular finite difference method and the 3-point central difference MOLs coupled with the RK(4,4) method with regard to the root mean square error values.
基金Funded by Young Teacher Fund of North China Electric Power University.(Serial Number:93204401)Important Research In Advance Fund of North China Electric Power University.and(934033011).
文摘An algorithm for approximating arbitrary NURBS curve with straight line is presented.Firstly,NURBS curve is acquired according to data points on the curve.Secondly,Approximating arbitrary NURBS curve is based on dichotomy.The resulting straight line approaches to the original curve with relatively fewer segments within the required tolerance.The example shows that the algorithm is simple and its approximation precision is high.The method is most useful in numerical control to drive the cutter along straight line or circular paths.
文摘The theory of RC uniform ladder networks based upon the recurrence of voltage and cur-rent functions is extended as a vehicle to analyse the dynamic characteristics of reg lines. Meth-ods for computing the time constants and simplifying the transfer functions for reg lines are alsopresented.
文摘The structure and microstructure of constituent phases in annealed IQC100-xDQCx alloys, made from mixtures of (Al62Cu25.5Fe12.5) icosahedral quasicrystal （IQC） and (Al70Co15Ni15) decagonal quasicrystal （DQC）, were studied by X-ray diffractometry（XRD）, scanning electron microscopy （SEM）, and energy-dispersive X-ray spectroscopy （EDAX）. These constituent phases are mostly approximants: λ, β and τ3. In addition, an Al-Cu-Co DQC phase is observed in (IQC80DQC20) alloy. The nature of these approximants and their relationship with the quasicrystals（QCs） are discussed; and the evolution of these phases is interpreted by the shifting of their e/a-constant lines in the Al-（Cu, Ni）-（Fe, Co） pseudo-ternary phase diagrams.
