In order to get rid of the dependence on high-precision centrifuges in accelerometer nonlinear coefficients calibration,this paper proposes a system-level calibration method for field condition.Firstly,a 42-dimension ...In order to get rid of the dependence on high-precision centrifuges in accelerometer nonlinear coefficients calibration,this paper proposes a system-level calibration method for field condition.Firstly,a 42-dimension Kalman filter is constructed to reduce impact brought by turntable.Then,a biaxial rotation path is designed based on the accelerometer output model,including orthogonal 22 positions and tilt 12 positions,which enhances gravity excitation on nonlinear coefficients of accelerometer.Finally,sampling is carried out for calibration and further experiments.The results of static inertial navigation experiments lasting 4000 s show that compared with the traditional method,the proposed method reduces the position error by about 390 m.展开更多
The current popular methods for decision making and project optimisation in mine ventilation contain a number of deficiencies as they are solely based on either subjective knowledge or objective information.This paper...The current popular methods for decision making and project optimisation in mine ventilation contain a number of deficiencies as they are solely based on either subjective knowledge or objective information.This paper presents a new approach to rank the alternatives by G1-coefficient of variation method.The focus of this approach is the use of the combination weighing,which is able to compensate for the deficiencies in the method of evaluation index single weighing.In the case study,an appropriate evaluation index system was established to determine the evaluation value of each ventilation mode.Then the proposed approach was used to select the best development face ventilation mode.The result shows that the proposed approach is able to rank the alternative development face ventilation mode reasonably,the combination weighing method had the advantages of both subjective and objective weighing methods in that it took into consideration of both the experience and wisdom of experts,and the new changes in objective conditions.This approach provides a more reasonable and reliable procedure to analyse and evaluate different ventilation modes.展开更多
To assess the water inflow which is more suitable to the actual conditions of tunnel,an empirical correlation about the permeability coefficient changing with depth is introduced.Supposing that the surrounding rock is...To assess the water inflow which is more suitable to the actual conditions of tunnel,an empirical correlation about the permeability coefficient changing with depth is introduced.Supposing that the surrounding rock is heterogeneous isotropy,the formula for calculating water inflow of tunnel with the nonlinear variation of permeability coefficient is deduced.By the contrast analysis with the existing formulas,the presented method has the similar value to them;moreover,the presented method has more simple form and easy to use.Due to parameter analysis,the water inflow decreases after considering the nonlinear variation of permeability coefficient.When the attenuation coefficient a>0,the water inflow increases first till reaches the maximum at a certain depth,then decreases and is close to 0 finally if deep enough.Thus,it is better to keep away from the certain depth where it is with the maximum water inflow for safe operation and economical construction,and reduce the water damage.Based on the analysis,the radius of tunnel has less impact on the amount of water inflow,and the water inflow just increases by 6.7% when the radius of tunnel increases by 1 m.展开更多
A drag coefficient(C_d) inversion method is introduced to study the variations of the drag coefficient for orbital satellites with spherical geometry.Drag coefficients of the four micro satellites in the Atmospheric N...A drag coefficient(C_d) inversion method is introduced to study the variations of the drag coefficient for orbital satellites with spherical geometry.Drag coefficients of the four micro satellites in the Atmospheric Neutral Density Experiment(ANDE) are compiled out with this new method. The Lomb-Scargle Periodgram(LSP) analysis of the four ANDE satellites' C__d series has shown that there are obvious 5,7,9,and 27 days' period in those data.Interesting results are found through comparing the LSP analysis with series of the daily solar radio flux at 10.7cm(F_(10.7) index),the Ap index,and the daily averaged solar wind speed at 1AU.All series in the same time interval have an obvious period of about 27 days,which has already been explained as the association with the 27 days' solar rotation.The oscillating periods less than 27 days are found in series of C_D,Ap and solar wind speed at 1 AU,e.g.,the 5,7,9 days period.However,these short periods disappeared in the time series of F_(10.7) index.The same periodicities of 5,7,9 days in Ap and solar wind are presented at the same time interval during the declining phase of solar cycle 23.While in the ascending phase of solar cycle 24,these short oscillations are not so obvious as that in the declining phase of solar cycle 23.These results provide definite evidence that the C_d variations with period of 5,7 and 9 days are produced by a combination of space weather effects caused by the solar wind and geomagnetic activity.展开更多
Underground energy and resource development,deep underground energy storage and other projects involve the global stability of multiple interconnected cavern groups under internal and external dynamic disturbances.An ...Underground energy and resource development,deep underground energy storage and other projects involve the global stability of multiple interconnected cavern groups under internal and external dynamic disturbances.An evaluation method of the global stability coefficient of underground caverns based on static overload and dynamic overload was proposed.Firstly,the global failure criterion for caverns was defined based on its band connection of plastic-strain between multi-caverns.Then,overloading calculation of the boundary geostress and seismic intensity on the caverns model was carried out,and the critical unstable state of multi-caverns can be identified,if the plastic-strain band appeared between caverns during these overloading processes.Thus,the global stability coefficient for the multi-caverns under static loading and earthquake was obtained based on the corresponding overloading coefficient.Practical analysis for the Yingliangbao(YLB)hydraulic caverns indicated that this method can not only effectively obtain the global stability coefficient of caverns under static and dynamic earthquake conditions,but also identify the caverns’high-risk zone of local instability through localized plastic strain of surrounding rock.This study can provide some reference for the layout design and seismic optimization of underground cavern group.展开更多
In this paper,a method for spoofing detection based on the variation of the signal’s carrier-to-noise ratio(CNR)is proposed.This method leverages the directionality of the antenna to induce varying gain changes in th...In this paper,a method for spoofing detection based on the variation of the signal’s carrier-to-noise ratio(CNR)is proposed.This method leverages the directionality of the antenna to induce varying gain changes in the signals across different incident directions,resulting in distinct CNR variations for each signal.A model is developed to calculate the variation value of the signal CNR based on the antenna gain pattern.This model enables the differentiation of the variation values of the CNR for authentic satellite signals and spoofing signals,thereby facilitating spoofing detection.The proposed method is capable of detecting spoofing signals with power and CNR similar to those of authentic satellite signals.The accuracy of the signal CNR variation value calculation model and the effectiveness of the spoofing detection method are verified through a series of experiments.In addition,the proposed spoofing detection method works not only for a single spoofing source but also for distributed spoofing sources.展开更多
Language variation is conditioned by complicated social factors such as class, age, occupation, education, sex, etc. all of which exert influences on one’s speech. Sex can be treated from two different angles in Euro...Language variation is conditioned by complicated social factors such as class, age, occupation, education, sex, etc. all of which exert influences on one’s speech. Sex can be treated from two different angles in European languages. One is biological sex; the other is gender (social gender). The social gender of a person plays a major role in influencing one’s speech.展开更多
By introducing a smooth merit function for the median function, a new smooth merit function for box constrained variational inequalities (BVIs) was constructed. The function is simple and has some good differential pr...By introducing a smooth merit function for the median function, a new smooth merit function for box constrained variational inequalities (BVIs) was constructed. The function is simple and has some good differential properties. A damped Newton type method was presented based on it.Global and local superlinear/quadratic convergence results were obtained under mild conditions, and the finite termination property was also shown for the linear BVIs. Numerical results suggest that the method is efficient and promising.展开更多
In practical application, it is very important to master the influence of structure parameters on the mid-span deflection quantificationally. For large-span and heavy-duty gantry cranes, the influence of the rigid leg...In practical application, it is very important to master the influence of structure parameters on the mid-span deflection quantificationally. For large-span and heavy-duty gantry cranes, the influence of the rigid leg and the soft leg on mid-span deflection has not been considered in the past. In the paper, the mathematical model is established for universal large-span and heavy-duty gantry cranes. The analytical solution for the mid-span deflection of gantry-frame structure girder is derived and obtained based on the variation principle by considering the coupling effect of the bending moments of girder and legs, the axial force and the secondary bending moments. The relation between the load and the deflection on the mid-span of the gantry-frame structure girder is known. Then, the experimental model is designed according to dimensional analysis method. And experiments were performed on the WEW-600 B type testing machine. Hackling experimental data, the regular of the load and deflection on the girder mid-span is obtained, namely, the deformation of the gantry-frame structure resists the external load to do work. The validity of the nonlinear analytical solution of the girder deflection is verified. Experimental results show that the analytical solution of the gantry-frame structure deflection has much higher calculation accuracy than previous calculation method. This work provides a theoretical basis for the design and inspection of gantry-frame structures.展开更多
3 degrees of freedom(DOF)exterior ballistic computer models are used in fragment studies to calculate individual trajectories of each fragment based on drag coefficient and the projected(presented)area in the directio...3 degrees of freedom(DOF)exterior ballistic computer models are used in fragment studies to calculate individual trajectories of each fragment based on drag coefficient and the projected(presented)area in the direction of velocity of center of mass.The expectation of a randomly distributed projected area is commonly used for fragments that tumble(random rotation)during flight.We forecast a model where the expected drag coefficient is dependent of shape and Mach number.Rotation or tumbling only affects the expected projected area.Models of projected areas during tumbling and rotation are presented.An examination of the data by Mc Cleskey(1988)indicates that the volume of the fragment to the power of2/3 is a better parameter to characterize the drag coefficient of the fragments than the maximum projected area.Hydrocode simulations are used to verify results and to study projected area and drag coefficient of fragments.展开更多
Total variation （TV） is widely applied in image process-ing. The assumption of TV is that an image consists of piecewise constants, however, it suffers from the so-cal ed staircase effect. In order to reduce the sta...Total variation （TV） is widely applied in image process-ing. The assumption of TV is that an image consists of piecewise constants, however, it suffers from the so-cal ed staircase effect. In order to reduce the staircase effect and preserve the edges when textures of image are extracted, a new image decomposition model is proposed in this paper. The proposed model is based on the to-tal generalized variation method which involves and balances the higher order of the structure. We also derive a numerical algorithm based on a primal-dual formulation that can be effectively imple-mented. Numerical experiments show that the proposed method can achieve a better trade-off between noise removal and texture extraction, while avoiding the staircase effect efficiently.展开更多
In foggy weather, images of outdoor scene are usually characterized with poor visibility as well as faint color saturation. The degraded hazy images may have substantial negative impact on most computer vision systems...In foggy weather, images of outdoor scene are usually characterized with poor visibility as well as faint color saturation. The degraded hazy images may have substantial negative impact on most computer vision systems. Thus image haze removal is of the practical significance in engineering. This paper proposes a fast and effective single image haze removal algorithm on the basis of the physics imaging model. To extract the global atmospheric light accurately, we exploit multiple prior rules underlying hazy images, and put forward a novel measurement to judge the likelihood that a pixel is regarded as the global atmospheric light. In addition, the rough transmission map is estimated through a multiscale fusion process based on the Laplace pyramid transform, and refined by a total variation model. Experimental results demonstrate the proposed method outperforms most of the state-of-the-art algorithms in terms of the dehazing quality, and achieves a trade-off between the computational efficiency and haze removal capability.展开更多
The research of groundwater vulnerability is the basic work to protect the groundwater. For utilizing groundwater resource continuably, groundwater vulnerability evaluation is necessary. Useful reference to protect, e...The research of groundwater vulnerability is the basic work to protect the groundwater. For utilizing groundwater resource continuably, groundwater vulnerability evaluation is necessary. Useful reference to protect, exploit and utilize on groundwater resource are provided rationally. According to the real condition of Sanjiang Plain, the indexes system is established based on the traditional DRASTIC model. The new system includes the following seven indexes： Depth of Water, Net Recharge, Aquifer Media, Soil Media, Conductivity of the Aquifer, Land Utilizing Ratio and Populace Density. The related analysis appears that the system is rather reasonable. Because traditional methods, such as analytic hierarchy process and fuzzy mathematics theory, can＇t be avoided human interference in selection of weights, they could lead to an imprecise result. In order to evaluate the groundwater vulnerability reasonably, entropy weight coefficient method is applied for the first time, which provides a new way to groundwater vulnerability evaluation. The method is a model whose weights are insured by the calculation process, so the artificial disturb can be avoided. It has been used to evaluate the groundwater vulnerability in Sanjiang Plain. The satisfied result is acquired. Comparably, the same result is acquired by the other method named projection pursuit evaluation based on real-coded accelerating genetic algorithm. It shows that entropy weight coefficient method is applicable on groundwater vulnerability evaluation. The evaluation result can provide reference on the decision-making departments.展开更多
The problems of time delay estimation of narrowband signals are presented. The disadvantages of the existing algorithms are analyzed, and a new narrowband time delay estimating algorithm based on correlation coefficie...The problems of time delay estimation of narrowband signals are presented. The disadvantages of the existing algorithms are analyzed, and a new narrowband time delay estimating algorithm based on correlation coefficient is proposed. The original time delay information is transfered into the delay between the autocorrelation and cross-correlation function, and the precise estimating result by wave-comparison is given. The algorithm proposed here is also compared with other algorithms and its advantages over other algorithms are proved. The theoretical analysis and simulation show the effectiveness of the proposed algorithm.展开更多
New models for image decomposition are proposed which separate an image into a cartoon, consisting only of geometric objects, and an oscillatory component, consisting of textures or noise. The proposed models are give...New models for image decomposition are proposed which separate an image into a cartoon, consisting only of geometric objects, and an oscillatory component, consisting of textures or noise. The proposed models are given in a variational formulation with adaptive regularization norms for both the cartoon and texture parts. The adaptive behavior preserves key features such as object boundaries and textures while avoiding staircasing in what should be smooth regions. This decomposition is computed by minimizing a convex functional which depends on the two variables u and v, alternatively in each variable. Experimental results and comparisons to validate the proposed models are presented.展开更多
The elevated supersaturation of total dissolved gas （TDG） downstream of a high-dam spill has deleterious effects on fish in a large range. A one-dimensional （l-D） longitudinal model is optimal for the prediction o...The elevated supersaturation of total dissolved gas （TDG） downstream of a high-dam spill has deleterious effects on fish in a large range. A one-dimensional （l-D） longitudinal model is optimal for the prediction of supersaturated TDG dissipation over a long distance. The key issue of the model is to determine the dissipation coefficient accurately. In agreement with field observations and experiment data, dimensional analysis and regression were performed to propose a formula for estimating the dissipation coefficient of supersaturated TDG in various rivers and reservoirs, and it involves the effects of the turbulence intensity, the hydro-pressure and the solid-liquid interface. The friction velocity, water depth, hydraulic radius and Froude number are independent variables in the formula which are easy to determine in practical applications. The 1-D longitudinal model is implemented to calculate the dissipation of TDG in a reach of the Jinsha River. Good agreement is found between the calculated results and field data for both the dissipation coefficient and the dissipation process.展开更多
Plastic variational principles are foundation to solve the boundary-value problems of plastic mechanics with the variational method(or energy method) and finite element method.The most convenient way of establishing d...Plastic variational principles are foundation to solve the boundary-value problems of plastic mechanics with the variational method(or energy method) and finite element method.The most convenient way of establishing different kinds of variational principles is to set up the extreme principle related to the studied problem.Based on a general new extreme principle-the Least work consumption principle,the variational principles of the rigid-plastic and rigid-viscoplastic material were derived.In comparison with existing methods,the method in this paper is more clear and direct,and the physical meaning is clear-cut.This method can offer a new way for establishing other kinds of variational principles.展开更多
Sheet metal is widely used on auto-bodies, plane-bodies and metal furniture, etc. For instance, a typical auto-body commonly consists of hundreds of sheet metal stamping parts. Because of its complexity of structure a...Sheet metal is widely used on auto-bodies, plane-bodies and metal furniture, etc. For instance, a typical auto-body commonly consists of hundreds of sheet metal stamping parts. Because of its complexity of structure and manufacturing process, auto-bodies inevitably have geometrical variation results from a number of different sources, such as the geometrical variation of stamping parts, the transformation of assembly process parameters and even the improper design concept. As more than 30% quality defects of an auto-body are born from the dimensional deviation of Body-In-White originated during the manufacturing process, effective diagnosis and control of dimensional faults are essential to the continuous improvement of the quality of vehicles. Especially during the period of new car launching or model changing when the assembly process was changed and adjusted frequently. For continuously improving the quality of modern cars, rapid dimensional variation causes identification becomes a challenging but essential work. In this paper, main variation causes of auto-body was firstly been cataloged and analyzed, then, a dimensional variation diagnostic reasoning and decision approach was developed through the combination of data mining and knowledge discovery techniques. This approach is driven by variation pattern identification which can be discovered from the dispersive, isolated massive measured data: Correlation Analysis (CA) and Maximal Tree (MT) methods were applied to extract the large variation group from massive multidimensional measured data, while multivariate statistical analysis (MSA) approach was used to discovery the principle variation pattern. A Decision Tree (DT) approach based on the knowledge of product and assembly process was developed to fulfill the "Hypothesis and Validation" characterized variation causes reasoning procedure. An practical application case with sudden and severe dimension variation on rear end panel in up/down direction was analyzed and successfully solved aided by the devloped variation diagnostic method, which have proved that the approach is effective and efficient.展开更多
基金supported by the National Natural Science Foundation of China(42276199).
文摘In order to get rid of the dependence on high-precision centrifuges in accelerometer nonlinear coefficients calibration,this paper proposes a system-level calibration method for field condition.Firstly,a 42-dimension Kalman filter is constructed to reduce impact brought by turntable.Then,a biaxial rotation path is designed based on the accelerometer output model,including orthogonal 22 positions and tilt 12 positions,which enhances gravity excitation on nonlinear coefficients of accelerometer.Finally,sampling is carried out for calibration and further experiments.The results of static inertial navigation experiments lasting 4000 s show that compared with the traditional method,the proposed method reduces the position error by about 390 m.
基金Projects(51504286,51374242)supported by the National Natural Science Foundation of ChinaProject(2015M572270)supported by China Postdoctoral Science FoundationProject(2015RS4004)supported by the Science and Technology Plan of Hunan Province,China
文摘The current popular methods for decision making and project optimisation in mine ventilation contain a number of deficiencies as they are solely based on either subjective knowledge or objective information.This paper presents a new approach to rank the alternatives by G1-coefficient of variation method.The focus of this approach is the use of the combination weighing,which is able to compensate for the deficiencies in the method of evaluation index single weighing.In the case study,an appropriate evaluation index system was established to determine the evaluation value of each ventilation mode.Then the proposed approach was used to select the best development face ventilation mode.The result shows that the proposed approach is able to rank the alternative development face ventilation mode reasonably,the combination weighing method had the advantages of both subjective and objective weighing methods in that it took into consideration of both the experience and wisdom of experts,and the new changes in objective conditions.This approach provides a more reasonable and reliable procedure to analyse and evaluate different ventilation modes.
基金Projects(51478477,51508562,51508563)supported by the National Natural Science Foundation of China
文摘To assess the water inflow which is more suitable to the actual conditions of tunnel,an empirical correlation about the permeability coefficient changing with depth is introduced.Supposing that the surrounding rock is heterogeneous isotropy,the formula for calculating water inflow of tunnel with the nonlinear variation of permeability coefficient is deduced.By the contrast analysis with the existing formulas,the presented method has the similar value to them;moreover,the presented method has more simple form and easy to use.Due to parameter analysis,the water inflow decreases after considering the nonlinear variation of permeability coefficient.When the attenuation coefficient a>0,the water inflow increases first till reaches the maximum at a certain depth,then decreases and is close to 0 finally if deep enough.Thus,it is better to keep away from the certain depth where it is with the maximum water inflow for safe operation and economical construction,and reduce the water damage.Based on the analysis,the radius of tunnel has less impact on the amount of water inflow,and the water inflow just increases by 6.7% when the radius of tunnel increases by 1 m.
基金Supported by the National Nature Science Foundation of China(40904080)the Advance Research Foundation of PLA University of Science and Technology
文摘A drag coefficient(C_d) inversion method is introduced to study the variations of the drag coefficient for orbital satellites with spherical geometry.Drag coefficients of the four micro satellites in the Atmospheric Neutral Density Experiment(ANDE) are compiled out with this new method. The Lomb-Scargle Periodgram(LSP) analysis of the four ANDE satellites' C__d series has shown that there are obvious 5,7,9,and 27 days' period in those data.Interesting results are found through comparing the LSP analysis with series of the daily solar radio flux at 10.7cm(F_(10.7) index),the Ap index,and the daily averaged solar wind speed at 1AU.All series in the same time interval have an obvious period of about 27 days,which has already been explained as the association with the 27 days' solar rotation.The oscillating periods less than 27 days are found in series of C_D,Ap and solar wind speed at 1 AU,e.g.,the 5,7,9 days period.However,these short periods disappeared in the time series of F_(10.7) index.The same periodicities of 5,7,9 days in Ap and solar wind are presented at the same time interval during the declining phase of solar cycle 23.While in the ascending phase of solar cycle 24,these short oscillations are not so obvious as that in the declining phase of solar cycle 23.These results provide definite evidence that the C_d variations with period of 5,7 and 9 days are produced by a combination of space weather effects caused by the solar wind and geomagnetic activity.
基金Project(2023YFC2907204)supported by the National Key Research and Development Program of ChinaProject(52325905)supported by the National Natural Science Foundation of ChinaProject(DJ-HXGG-2023-16)supported by the Key Technology Research Projects of Power China。
文摘Underground energy and resource development,deep underground energy storage and other projects involve the global stability of multiple interconnected cavern groups under internal and external dynamic disturbances.An evaluation method of the global stability coefficient of underground caverns based on static overload and dynamic overload was proposed.Firstly,the global failure criterion for caverns was defined based on its band connection of plastic-strain between multi-caverns.Then,overloading calculation of the boundary geostress and seismic intensity on the caverns model was carried out,and the critical unstable state of multi-caverns can be identified,if the plastic-strain band appeared between caverns during these overloading processes.Thus,the global stability coefficient for the multi-caverns under static loading and earthquake was obtained based on the corresponding overloading coefficient.Practical analysis for the Yingliangbao(YLB)hydraulic caverns indicated that this method can not only effectively obtain the global stability coefficient of caverns under static and dynamic earthquake conditions,but also identify the caverns’high-risk zone of local instability through localized plastic strain of surrounding rock.This study can provide some reference for the layout design and seismic optimization of underground cavern group.
基金supported by the National Natural Science Foundation of China(62273195).
文摘In this paper,a method for spoofing detection based on the variation of the signal’s carrier-to-noise ratio(CNR)is proposed.This method leverages the directionality of the antenna to induce varying gain changes in the signals across different incident directions,resulting in distinct CNR variations for each signal.A model is developed to calculate the variation value of the signal CNR based on the antenna gain pattern.This model enables the differentiation of the variation values of the CNR for authentic satellite signals and spoofing signals,thereby facilitating spoofing detection.The proposed method is capable of detecting spoofing signals with power and CNR similar to those of authentic satellite signals.The accuracy of the signal CNR variation value calculation model and the effectiveness of the spoofing detection method are verified through a series of experiments.In addition,the proposed spoofing detection method works not only for a single spoofing source but also for distributed spoofing sources.
文摘Language variation is conditioned by complicated social factors such as class, age, occupation, education, sex, etc. all of which exert influences on one’s speech. Sex can be treated from two different angles in European languages. One is biological sex; the other is gender (social gender). The social gender of a person plays a major role in influencing one’s speech.
基金Project supported by the Teaching and Research Award Program for the Outstanding YoungTeachers in Higher Education Institutes of Munistry of Education, P.R.China
文摘By introducing a smooth merit function for the median function, a new smooth merit function for box constrained variational inequalities (BVIs) was constructed. The function is simple and has some good differential properties. A damped Newton type method was presented based on it.Global and local superlinear/quadratic convergence results were obtained under mild conditions, and the finite termination property was also shown for the linear BVIs. Numerical results suggest that the method is efficient and promising.
基金Project(51175442)supported by the National Natural Science Foundation of ChinaProject(QD2012A09)supported by Teachers’College Research Project,ChinaProject(14ZA0263)supported by Research Project of Sichuan Provincial Department of Education,China
文摘In practical application, it is very important to master the influence of structure parameters on the mid-span deflection quantificationally. For large-span and heavy-duty gantry cranes, the influence of the rigid leg and the soft leg on mid-span deflection has not been considered in the past. In the paper, the mathematical model is established for universal large-span and heavy-duty gantry cranes. The analytical solution for the mid-span deflection of gantry-frame structure girder is derived and obtained based on the variation principle by considering the coupling effect of the bending moments of girder and legs, the axial force and the secondary bending moments. The relation between the load and the deflection on the mid-span of the gantry-frame structure girder is known. Then, the experimental model is designed according to dimensional analysis method. And experiments were performed on the WEW-600 B type testing machine. Hackling experimental data, the regular of the load and deflection on the girder mid-span is obtained, namely, the deformation of the gantry-frame structure resists the external load to do work. The validity of the nonlinear analytical solution of the girder deflection is verified. Experimental results show that the analytical solution of the gantry-frame structure deflection has much higher calculation accuracy than previous calculation method. This work provides a theoretical basis for the design and inspection of gantry-frame structures.
文摘3 degrees of freedom(DOF)exterior ballistic computer models are used in fragment studies to calculate individual trajectories of each fragment based on drag coefficient and the projected(presented)area in the direction of velocity of center of mass.The expectation of a randomly distributed projected area is commonly used for fragments that tumble(random rotation)during flight.We forecast a model where the expected drag coefficient is dependent of shape and Mach number.Rotation or tumbling only affects the expected projected area.Models of projected areas during tumbling and rotation are presented.An examination of the data by Mc Cleskey(1988)indicates that the volume of the fragment to the power of2/3 is a better parameter to characterize the drag coefficient of the fragments than the maximum projected area.Hydrocode simulations are used to verify results and to study projected area and drag coefficient of fragments.
基金supported by the National Natural Science Foundation of China(6127129461301229)+1 种基金the Doctoral Research Fund of Henan University of Science and Technology(0900170809001751)
文摘Total variation （TV） is widely applied in image process-ing. The assumption of TV is that an image consists of piecewise constants, however, it suffers from the so-cal ed staircase effect. In order to reduce the staircase effect and preserve the edges when textures of image are extracted, a new image decomposition model is proposed in this paper. The proposed model is based on the to-tal generalized variation method which involves and balances the higher order of the structure. We also derive a numerical algorithm based on a primal-dual formulation that can be effectively imple-mented. Numerical experiments show that the proposed method can achieve a better trade-off between noise removal and texture extraction, while avoiding the staircase effect efficiently.
基金supported by the National Natural Science Foundation of China(61571241)the Industry-University-research Prospective Joint Project of Jiangsu Province(BY2014014)+2 种基金the Major Projects of Jiangsu Province University Natural Science Research(15KJA510002)the Jiangsu Province Graduate Research and Innovation Project(CXZZ130476)the Science Research Fund of NUPT(NY215169)
文摘In foggy weather, images of outdoor scene are usually characterized with poor visibility as well as faint color saturation. The degraded hazy images may have substantial negative impact on most computer vision systems. Thus image haze removal is of the practical significance in engineering. This paper proposes a fast and effective single image haze removal algorithm on the basis of the physics imaging model. To extract the global atmospheric light accurately, we exploit multiple prior rules underlying hazy images, and put forward a novel measurement to judge the likelihood that a pixel is regarded as the global atmospheric light. In addition, the rough transmission map is estimated through a multiscale fusion process based on the Laplace pyramid transform, and refined by a total variation model. Experimental results demonstrate the proposed method outperforms most of the state-of-the-art algorithms in terms of the dehazing quality, and achieves a trade-off between the computational efficiency and haze removal capability.
基金Supported by the National Natural Science Foundation of China(30400275)the Tackle Key Problems of Heilongjiang Province(the Hobbledehoy Science Fund of Heilongjiang Province)(QC04C28)
文摘The research of groundwater vulnerability is the basic work to protect the groundwater. For utilizing groundwater resource continuably, groundwater vulnerability evaluation is necessary. Useful reference to protect, exploit and utilize on groundwater resource are provided rationally. According to the real condition of Sanjiang Plain, the indexes system is established based on the traditional DRASTIC model. The new system includes the following seven indexes： Depth of Water, Net Recharge, Aquifer Media, Soil Media, Conductivity of the Aquifer, Land Utilizing Ratio and Populace Density. The related analysis appears that the system is rather reasonable. Because traditional methods, such as analytic hierarchy process and fuzzy mathematics theory, can＇t be avoided human interference in selection of weights, they could lead to an imprecise result. In order to evaluate the groundwater vulnerability reasonably, entropy weight coefficient method is applied for the first time, which provides a new way to groundwater vulnerability evaluation. The method is a model whose weights are insured by the calculation process, so the artificial disturb can be avoided. It has been used to evaluate the groundwater vulnerability in Sanjiang Plain. The satisfied result is acquired. Comparably, the same result is acquired by the other method named projection pursuit evaluation based on real-coded accelerating genetic algorithm. It shows that entropy weight coefficient method is applicable on groundwater vulnerability evaluation. The evaluation result can provide reference on the decision-making departments.
基金supported partly by the National Natural Science Foundation of China(6037208130570475)the Education Ministry Doctoral Degree Foundation of China(20050141025).
文摘The problems of time delay estimation of narrowband signals are presented. The disadvantages of the existing algorithms are analyzed, and a new narrowband time delay estimating algorithm based on correlation coefficient is proposed. The original time delay information is transfered into the delay between the autocorrelation and cross-correlation function, and the precise estimating result by wave-comparison is given. The algorithm proposed here is also compared with other algorithms and its advantages over other algorithms are proved. The theoretical analysis and simulation show the effectiveness of the proposed algorithm.
文摘New models for image decomposition are proposed which separate an image into a cartoon, consisting only of geometric objects, and an oscillatory component, consisting of textures or noise. The proposed models are given in a variational formulation with adaptive regularization norms for both the cartoon and texture parts. The adaptive behavior preserves key features such as object boundaries and textures while avoiding staircasing in what should be smooth regions. This decomposition is computed by minimizing a convex functional which depends on the two variables u and v, alternatively in each variable. Experimental results and comparisons to validate the proposed models are presented.
基金Projects(51179111,51279115)supported by the National Natural Science Foundation of ChinaProject(20110181110073)supported by the Doctoral Programs Foundation of Ministry of Education of China
文摘The elevated supersaturation of total dissolved gas （TDG） downstream of a high-dam spill has deleterious effects on fish in a large range. A one-dimensional （l-D） longitudinal model is optimal for the prediction of supersaturated TDG dissipation over a long distance. The key issue of the model is to determine the dissipation coefficient accurately. In agreement with field observations and experiment data, dimensional analysis and regression were performed to propose a formula for estimating the dissipation coefficient of supersaturated TDG in various rivers and reservoirs, and it involves the effects of the turbulence intensity, the hydro-pressure and the solid-liquid interface. The friction velocity, water depth, hydraulic radius and Froude number are independent variables in the formula which are easy to determine in practical applications. The 1-D longitudinal model is implemented to calculate the dissipation of TDG in a reach of the Jinsha River. Good agreement is found between the calculated results and field data for both the dissipation coefficient and the dissipation process.
文摘Plastic variational principles are foundation to solve the boundary-value problems of plastic mechanics with the variational method(or energy method) and finite element method.The most convenient way of establishing different kinds of variational principles is to set up the extreme principle related to the studied problem.Based on a general new extreme principle-the Least work consumption principle,the variational principles of the rigid-plastic and rigid-viscoplastic material were derived.In comparison with existing methods,the method in this paper is more clear and direct,and the physical meaning is clear-cut.This method can offer a new way for establishing other kinds of variational principles.
文摘Sheet metal is widely used on auto-bodies, plane-bodies and metal furniture, etc. For instance, a typical auto-body commonly consists of hundreds of sheet metal stamping parts. Because of its complexity of structure and manufacturing process, auto-bodies inevitably have geometrical variation results from a number of different sources, such as the geometrical variation of stamping parts, the transformation of assembly process parameters and even the improper design concept. As more than 30% quality defects of an auto-body are born from the dimensional deviation of Body-In-White originated during the manufacturing process, effective diagnosis and control of dimensional faults are essential to the continuous improvement of the quality of vehicles. Especially during the period of new car launching or model changing when the assembly process was changed and adjusted frequently. For continuously improving the quality of modern cars, rapid dimensional variation causes identification becomes a challenging but essential work. In this paper, main variation causes of auto-body was firstly been cataloged and analyzed, then, a dimensional variation diagnostic reasoning and decision approach was developed through the combination of data mining and knowledge discovery techniques. This approach is driven by variation pattern identification which can be discovered from the dispersive, isolated massive measured data: Correlation Analysis (CA) and Maximal Tree (MT) methods were applied to extract the large variation group from massive multidimensional measured data, while multivariate statistical analysis (MSA) approach was used to discovery the principle variation pattern. A Decision Tree (DT) approach based on the knowledge of product and assembly process was developed to fulfill the "Hypothesis and Validation" characterized variation causes reasoning procedure. An practical application case with sudden and severe dimension variation on rear end panel in up/down direction was analyzed and successfully solved aided by the devloped variation diagnostic method, which have proved that the approach is effective and efficient.
