[Objective] The aim was to evaluate the regional eco-environmental quality by using the universal index formula of parameterization combination operator based normalized index values.[Method] Through setting reference...[Objective] The aim was to evaluate the regional eco-environmental quality by using the universal index formula of parameterization combination operator based normalized index values.[Method] Through setting reference values and normalized transformation formulae for typical ecological environmental indexes appropriately,the difference among the standard normalized values would become very small after normalized transformation,and the ecological environmental indices expressed by normalized values can be equivalent to normalized indices.Under certain optimization conditions,shuffled frog leaping based on immune evolutionary particle swarm optimization algorithm was applied to optimize the parameters in parameterization combination operator formula,and the universal index formula suited to eco-environmental quality assessment was established finally.[Result] The universal index formula of parameterization combination operator,appropriate for any m(1≤m≤23) ecological environmental indices,was used to assess the eco-environmental quality of towns surrounding Headland Reservoir,and the results were in full accordance with those of unascertained measure method,that is,the eco-environmental quality of five towns around Headland Reservoir was the fourth grade.[Conclusion]The universal index formula of parameterization combination operator,suited to eco-environmental quality evaluation,is simple and intuitive in form,easy in computation and universal in application.展开更多
Proper analysis of petrophysical parameter sensitivity from well log data can greatly improve the ability to discriminate hydrocarbon-bearing rocks. In this paper we discuss a petrophysical analysis method for the sel...Proper analysis of petrophysical parameter sensitivity from well log data can greatly improve the ability to discriminate hydrocarbon-bearing rocks. In this paper we discuss a petrophysical analysis method for the selection and application of higher sensitivity seismic attribute parameters to improve the ability to discriminate fluid and lithology. To better integrate with seismic interpretation, we construct a template to highlight rock physics parameters in sensitivity space, providing guidance for the quantitative seismic interpretation of hydrocarbon-bearing reservoirs.展开更多
The relative sensitivities of structural dynamical parameters were analyzed using a directive derivation method. The neural network is able to approximate arbitrary nonlinear mapping relationship, so it is a powerful ...The relative sensitivities of structural dynamical parameters were analyzed using a directive derivation method. The neural network is able to approximate arbitrary nonlinear mapping relationship, so it is a powerful damage identification tool for unknown systems. A neural network-based approach was presented for the structural damage detection. The combined parameters were presented as the input vector of the neural network, which computed with the change rates of the several former natural frequencies ( C), the change ratios of the frequencies ( R), and the assurance criterions of flexibilities (A). Some numerical simulation examples, such as, cantilever and truss with different damage extends and different damage locations were analyzed. The results indicate that the combined parameters are more suitable for the input patterns of neural networks than the other parameters alone.展开更多
Feedback supply chain is a key structure in the supply chain system, and the development of feedback supply chain for biogas biomass energy is one of the important ways of the rural ecological civilization constructio...Feedback supply chain is a key structure in the supply chain system, and the development of feedback supply chain for biogas biomass energy is one of the important ways of the rural ecological civilization construction. Presently, the efficiency problem of biogas supply chain in rural China has been restricting the development of biogas biomass energy business. This article, on the basis of combination of regulation parameters, describes the dynamic changes in the system, using differential equations integrated with simulation to reveal the rules of regulation parameters to investigate the efficiency problem in the biogas supply chain. First of all, on the basis of the actual situation, the flow level and flow rate system structure model and simulation equation set are established for the biogas energy feedback supply chain from a scale livestock farm to peasant households; On the basis of the differentiability of the simulation equation a third order inhomogeneous differential equation with constant coefficients containing regulative parameters is established for the quantity of biogas stored in the feedback supply chain. A theorem and its corollaries are established for the operating efficiency of supply chain to reveal the change law of the quantity of biogas, the quantity of biogas consumed daily by peasant households and its standard-reaching rate as well as other variables.展开更多
A YDC type hydraulic hammer is a new valve-type double action hydraulic hammer suitable for oil and gas well drilling.It is hard to find out the optimal matching relationship among various factors based on experience ...A YDC type hydraulic hammer is a new valve-type double action hydraulic hammer suitable for oil and gas well drilling.It is hard to find out the optimal matching relationship among various factors based on experience and experiments,for the matching relationships of inner pressure is complex and the impact performance is influenced by many factors.In this paper,the operating principle of a YDC type hydraulic hammer was investigated,the force applied to the main moving components(valve core and hammer)was analyzed and a dynamic model of valve core and hammer in each operating stage was established.Then,a hydraulic hammer performance optimization design software was developed on the Matlab software platform,and the performance parameters calculated by the software were compared with the laboratory test results.The following research results were obtained.Firstly,single impact energy,impact frequency and impact power increase with the increase of pump displacement or the decrease of flow bean diameter,and they increase firstly and then decrease with the increase of area difference between the upper and lower chambers.Secondly,with the increase of hammer weight,single impact energy and impact power increase,but the impact frequency decreases slowly.Thirdly,with the increase of hammer travel,single impact energy presents an increasing trend,impact frequency presents a decreasing trend and impact power basically remains unchanged.Fourthly,with the increase of valve core weight,single impact energy presents an increasing trend,while both impact frequency and impact power decrease.Fifthly,the parameter combination corresponding to the optimal single impact energy and impact power is A5B1C5D4E3F2,and the effect of displacement on single impact energy and impact power is the greatest.It is concluded that under the existing displacement and pressure of drilling pumps,the impact performance of the hydraulic hammer can be increased effectively by improving the structure of the hydraulic hammer and thus increasing its work displacement.展开更多
Using the visualized experimental device of temporary plugging in hydraulic fractures, the plugging behaviors of temporary plugging particles with different sizes and concentrations in hydraulic fractures were experim...Using the visualized experimental device of temporary plugging in hydraulic fractures, the plugging behaviors of temporary plugging particles with different sizes and concentrations in hydraulic fractures were experimentally analyzed under the conditions of different carrier fluid displacements and viscosities. The results show that the greater the carrier fluid viscosity and displacement, the more difficult it is to form a plugging layer, and that the larger the size and concentration of the temporary plugging particle, the less difficult it is to form a plugging layer. When the ratio of particle size to fracture width is 0.45, the formation of the plugging layer is mainly controlled by the mass concentration of the temporary plugging particle and the viscosity of the carrier fluid, and a stable plugging layer cannot form if the mass concentration of the temporary plugging particle is less than 20 kg/m^(3)or the viscosity of the carrier fluid is greater than 3 mPa·s. When the ratio of particle size to fracture width is 0.60, the formation of the plugging layer is mainly controlled by the mass concentration of the temporary plugging particle, and a stable plugging layer cannot form if the mass concentration of the temporary plugging particle is less than 10 kg/m^(3). When the ratio of particle size to fracture width is 0.75, the formation of the plugging layer is basically not affected by other parameters, and a stable plugging layer can form within the experimental conditions. The formation process of plugging layer includes two stages and four modes. The main controlling factors affecting the formation mode are the ratio of particle size to fracture width, carrier fluid displacement and carrier fluid viscosity.展开更多
Mesh parameterization is one of the fundamental operations in computer graphics(CG) and computeraided design(CAD). In this paper, we propose a novel local/global parameterization approach, ARAP++, for singleand multi-...Mesh parameterization is one of the fundamental operations in computer graphics(CG) and computeraided design(CAD). In this paper, we propose a novel local/global parameterization approach, ARAP++, for singleand multi-boundary triangular meshes. It is an extension of the as-rigid-as-possible(ARAP) approach, which stitches together 1-ring patches instead of individual triangles. To optimize the spring energy, we introduce a linear iterative scheme which employs convex combination weights and a fitting Jacobian matrix corresponding to a prescribed family of transformations. Our algorithm is simple, efficient, and robust. The geometric properties(angle and area)of the original model can also be preserved by appropriately prescribing the singular values of the fitting matrix. To reduce the area and stretch distortions for high-curvature models, a stretch operator is introduced. Numerical results demonstrate that ARAP++ outperforms several state-of-the-art methods in terms of controlling the distortions of angle, area, and stretch. Furthermore, it achieves a better visualization performance for several applications, such as texture mapping and surface remeshing.展开更多
Optical coherence tomography(OCT)has moved to the forefront of imaging modalities in the management of glaucoma and retinal diseases.It is modifying how glaucoma and glaucoma progression are diagnosed clinically and a...Optical coherence tomography(OCT)has moved to the forefront of imaging modalities in the management of glaucoma and retinal diseases.It is modifying how glaucoma and glaucoma progression are diagnosed clinically and augmenting our understanding of the disease.OCT provides multiple parameters from various anatomic areas for glaucoma diagnosis,evaluation of treatment efficacy,and progression monitoring.While the use of multiple parameters has increased the likelihood of detecting early structural changes,diagnosing glaucoma in early stages is often challenging when the damages are subtle and not apparent on OCT scans,in addition to the fact that assessment of OCT parameters often yields conflicting findings.One promising approach is to combine multiple individual parameters into a composite parameter from the same test to improve diagnostic accuracy,sensitivity,and specificity.This review presents current evidence regarding the value of spectral domain OCT composite parameters in diagnosing early glaucoma.展开更多
Some typical samples are used to explore the quantitative correlation with their features between a convective cloud and its rainfall field,with which to develop two morphological functions for the correlation and by ...Some typical samples are used to explore the quantitative correlation with their features between a convective cloud and its rainfall field,with which to develop two morphological functions for the correlation and by singling out their most suitable groups of parameters we propose a model for quantitatively estimating precipitation in the context o{ the in-advance recognition of meso-α convective system properties and its precipitating center.From the model fitting precision and forecasting accuracy we find that it is feasible to utilize geostationary meteorological satellite (GMS) digitalized imagery for estimating short-term rainfall in a quantitative manner.Also,evidence suggests that the model is supposed to be restricted in its applicability due to the fact that the employed samples are from rather typical rainfall events that are large-scale,slow-moving and have well-defined genesis and dissipative stages.展开更多
This paper develops a new combined network equilibrium model by using more behaviorally sound mathematical forms to represent the four travel choices（i.e., trip frequency,destination, mode, and route） in a conventio...This paper develops a new combined network equilibrium model by using more behaviorally sound mathematical forms to represent the four travel choices（i.e., trip frequency,destination, mode, and route） in a conventional travel demand forecasting process. Trip frequency choice relates to the traveler decision on “making a trip” or “not making a trip”so it is given by a binary logit model. Destination choice is formulated as a parameterized dogit model of which the captivity parameters（expressed as functions of independent variables） allow individual travelers to be captive to specific destinations. Mode choice is given by a two-level nested logit model to avoid IIA restriction. Trip assignment is based on Wardrop＇s “user-optimized” principle. All model forms describing travel choices are in response to the level of services incurred by the transportation system. Through the introduction of inclusive values, the traveler decisions concerning trip frequency, destination, mode, and route choices are inherently interrelated and jointly determined.To obtain solutions of the new combined model, it was reformulated as an equivalent convex programming problem with linear constraints, a great advantage from the computational aspects. The model was applied empirically to a transportation network in New Jersey. The application results show that the new model is consistently better than the commonly used logit combined model in reproducing the observed trip flows from origin zones, origin to destination（O-D） trip flows, O-D trip flows by mode, and trip flows on the network links.展开更多
基金Supported by Groundwork Project of Science and Technology(2009IM020100)National Natural Science Foundation of China(50779042,50739002,41101542)
文摘[Objective] The aim was to evaluate the regional eco-environmental quality by using the universal index formula of parameterization combination operator based normalized index values.[Method] Through setting reference values and normalized transformation formulae for typical ecological environmental indexes appropriately,the difference among the standard normalized values would become very small after normalized transformation,and the ecological environmental indices expressed by normalized values can be equivalent to normalized indices.Under certain optimization conditions,shuffled frog leaping based on immune evolutionary particle swarm optimization algorithm was applied to optimize the parameters in parameterization combination operator formula,and the universal index formula suited to eco-environmental quality assessment was established finally.[Result] The universal index formula of parameterization combination operator,appropriate for any m(1≤m≤23) ecological environmental indices,was used to assess the eco-environmental quality of towns surrounding Headland Reservoir,and the results were in full accordance with those of unascertained measure method,that is,the eco-environmental quality of five towns around Headland Reservoir was the fourth grade.[Conclusion]The universal index formula of parameterization combination operator,suited to eco-environmental quality evaluation,is simple and intuitive in form,easy in computation and universal in application.
文摘Proper analysis of petrophysical parameter sensitivity from well log data can greatly improve the ability to discriminate hydrocarbon-bearing rocks. In this paper we discuss a petrophysical analysis method for the selection and application of higher sensitivity seismic attribute parameters to improve the ability to discriminate fluid and lithology. To better integrate with seismic interpretation, we construct a template to highlight rock physics parameters in sensitivity space, providing guidance for the quantitative seismic interpretation of hydrocarbon-bearing reservoirs.
文摘The relative sensitivities of structural dynamical parameters were analyzed using a directive derivation method. The neural network is able to approximate arbitrary nonlinear mapping relationship, so it is a powerful damage identification tool for unknown systems. A neural network-based approach was presented for the structural damage detection. The combined parameters were presented as the input vector of the neural network, which computed with the change rates of the several former natural frequencies ( C), the change ratios of the frequencies ( R), and the assurance criterions of flexibilities (A). Some numerical simulation examples, such as, cantilever and truss with different damage extends and different damage locations were analyzed. The results indicate that the combined parameters are more suitable for the input patterns of neural networks than the other parameters alone.
基金supported by the National Natural Science Funds(71261018,71171208,71473285)
文摘Feedback supply chain is a key structure in the supply chain system, and the development of feedback supply chain for biogas biomass energy is one of the important ways of the rural ecological civilization construction. Presently, the efficiency problem of biogas supply chain in rural China has been restricting the development of biogas biomass energy business. This article, on the basis of combination of regulation parameters, describes the dynamic changes in the system, using differential equations integrated with simulation to reveal the rules of regulation parameters to investigate the efficiency problem in the biogas supply chain. First of all, on the basis of the actual situation, the flow level and flow rate system structure model and simulation equation set are established for the biogas energy feedback supply chain from a scale livestock farm to peasant households; On the basis of the differentiability of the simulation equation a third order inhomogeneous differential equation with constant coefficients containing regulative parameters is established for the quantity of biogas stored in the feedback supply chain. A theorem and its corollaries are established for the operating efficiency of supply chain to reveal the change law of the quantity of biogas, the quantity of biogas consumed daily by peasant households and its standard-reaching rate as well as other variables.
基金supported by CNPC Scientific Research and Technology Development Project“Study on New Drilling Techniques and Methods”(No.2014A-4211).
文摘A YDC type hydraulic hammer is a new valve-type double action hydraulic hammer suitable for oil and gas well drilling.It is hard to find out the optimal matching relationship among various factors based on experience and experiments,for the matching relationships of inner pressure is complex and the impact performance is influenced by many factors.In this paper,the operating principle of a YDC type hydraulic hammer was investigated,the force applied to the main moving components(valve core and hammer)was analyzed and a dynamic model of valve core and hammer in each operating stage was established.Then,a hydraulic hammer performance optimization design software was developed on the Matlab software platform,and the performance parameters calculated by the software were compared with the laboratory test results.The following research results were obtained.Firstly,single impact energy,impact frequency and impact power increase with the increase of pump displacement or the decrease of flow bean diameter,and they increase firstly and then decrease with the increase of area difference between the upper and lower chambers.Secondly,with the increase of hammer weight,single impact energy and impact power increase,but the impact frequency decreases slowly.Thirdly,with the increase of hammer travel,single impact energy presents an increasing trend,impact frequency presents a decreasing trend and impact power basically remains unchanged.Fourthly,with the increase of valve core weight,single impact energy presents an increasing trend,while both impact frequency and impact power decrease.Fifthly,the parameter combination corresponding to the optimal single impact energy and impact power is A5B1C5D4E3F2,and the effect of displacement on single impact energy and impact power is the greatest.It is concluded that under the existing displacement and pressure of drilling pumps,the impact performance of the hydraulic hammer can be increased effectively by improving the structure of the hydraulic hammer and thus increasing its work displacement.
基金Supported by National Natural Science Foundation of China (U21A20105)Science and Technology Innovation Fund of PetroChina (2020D-5007-0208)。
文摘Using the visualized experimental device of temporary plugging in hydraulic fractures, the plugging behaviors of temporary plugging particles with different sizes and concentrations in hydraulic fractures were experimentally analyzed under the conditions of different carrier fluid displacements and viscosities. The results show that the greater the carrier fluid viscosity and displacement, the more difficult it is to form a plugging layer, and that the larger the size and concentration of the temporary plugging particle, the less difficult it is to form a plugging layer. When the ratio of particle size to fracture width is 0.45, the formation of the plugging layer is mainly controlled by the mass concentration of the temporary plugging particle and the viscosity of the carrier fluid, and a stable plugging layer cannot form if the mass concentration of the temporary plugging particle is less than 20 kg/m^(3)or the viscosity of the carrier fluid is greater than 3 mPa·s. When the ratio of particle size to fracture width is 0.60, the formation of the plugging layer is mainly controlled by the mass concentration of the temporary plugging particle, and a stable plugging layer cannot form if the mass concentration of the temporary plugging particle is less than 10 kg/m^(3). When the ratio of particle size to fracture width is 0.75, the formation of the plugging layer is basically not affected by other parameters, and a stable plugging layer can form within the experimental conditions. The formation process of plugging layer includes two stages and four modes. The main controlling factors affecting the formation mode are the ratio of particle size to fracture width, carrier fluid displacement and carrier fluid viscosity.
基金supported by the National Natural Science Foundation of China(Nos.61432003,61572105,11171052,and 61328206)
文摘Mesh parameterization is one of the fundamental operations in computer graphics(CG) and computeraided design(CAD). In this paper, we propose a novel local/global parameterization approach, ARAP++, for singleand multi-boundary triangular meshes. It is an extension of the as-rigid-as-possible(ARAP) approach, which stitches together 1-ring patches instead of individual triangles. To optimize the spring energy, we introduce a linear iterative scheme which employs convex combination weights and a fitting Jacobian matrix corresponding to a prescribed family of transformations. Our algorithm is simple, efficient, and robust. The geometric properties(angle and area)of the original model can also be preserved by appropriately prescribing the singular values of the fitting matrix. To reduce the area and stretch distortions for high-curvature models, a stretch operator is introduced. Numerical results demonstrate that ARAP++ outperforms several state-of-the-art methods in terms of controlling the distortions of angle, area, and stretch. Furthermore, it achieves a better visualization performance for several applications, such as texture mapping and surface remeshing.
基金supported by the Department of Ophthalmology,University of North Carolina at Chapel Hill,USA,and by CTSA Grant UL1 TR001863 from the National Center for Advancing Translational Science,Yale University,New Haven,Connecticut,USA.
文摘Optical coherence tomography(OCT)has moved to the forefront of imaging modalities in the management of glaucoma and retinal diseases.It is modifying how glaucoma and glaucoma progression are diagnosed clinically and augmenting our understanding of the disease.OCT provides multiple parameters from various anatomic areas for glaucoma diagnosis,evaluation of treatment efficacy,and progression monitoring.While the use of multiple parameters has increased the likelihood of detecting early structural changes,diagnosing glaucoma in early stages is often challenging when the damages are subtle and not apparent on OCT scans,in addition to the fact that assessment of OCT parameters often yields conflicting findings.One promising approach is to combine multiple individual parameters into a composite parameter from the same test to improve diagnostic accuracy,sensitivity,and specificity.This review presents current evidence regarding the value of spectral domain OCT composite parameters in diagnosing early glaucoma.
文摘Some typical samples are used to explore the quantitative correlation with their features between a convective cloud and its rainfall field,with which to develop two morphological functions for the correlation and by singling out their most suitable groups of parameters we propose a model for quantitatively estimating precipitation in the context o{ the in-advance recognition of meso-α convective system properties and its precipitating center.From the model fitting precision and forecasting accuracy we find that it is feasible to utilize geostationary meteorological satellite (GMS) digitalized imagery for estimating short-term rainfall in a quantitative manner.Also,evidence suggests that the model is supposed to be restricted in its applicability due to the fact that the employed samples are from rather typical rainfall events that are large-scale,slow-moving and have well-defined genesis and dissipative stages.
文摘This paper develops a new combined network equilibrium model by using more behaviorally sound mathematical forms to represent the four travel choices（i.e., trip frequency,destination, mode, and route） in a conventional travel demand forecasting process. Trip frequency choice relates to the traveler decision on “making a trip” or “not making a trip”so it is given by a binary logit model. Destination choice is formulated as a parameterized dogit model of which the captivity parameters（expressed as functions of independent variables） allow individual travelers to be captive to specific destinations. Mode choice is given by a two-level nested logit model to avoid IIA restriction. Trip assignment is based on Wardrop＇s “user-optimized” principle. All model forms describing travel choices are in response to the level of services incurred by the transportation system. Through the introduction of inclusive values, the traveler decisions concerning trip frequency, destination, mode, and route choices are inherently interrelated and jointly determined.To obtain solutions of the new combined model, it was reformulated as an equivalent convex programming problem with linear constraints, a great advantage from the computational aspects. The model was applied empirically to a transportation network in New Jersey. The application results show that the new model is consistently better than the commonly used logit combined model in reproducing the observed trip flows from origin zones, origin to destination（O-D） trip flows, O-D trip flows by mode, and trip flows on the network links.
