Methane in-situ explosion fracturing(MISEF)enhances permeability in shale reservoirs by detonating desorbed methane to generate detonation waves in perforations.Fracture propagation in bedding shale under varying expl...Methane in-situ explosion fracturing(MISEF)enhances permeability in shale reservoirs by detonating desorbed methane to generate detonation waves in perforations.Fracture propagation in bedding shale under varying explosion loads remains unclear.In this study,prefabricated perforated shale samples with parallel and vertical bedding are fractured under five distinct explosion loads using a MISEF experimental setup.High-frequency explosion pressure-time curves were monitored within an equivalent perforation,and computed tomography scanning along with three-dimensional reconstruction techniques were used to investigate fracture propagation patterns.Additionally,the formation mechanism and influencing factors of explosion crack-generated fines(CGF)were clarified by analyzing the morphology and statistics of explosion debris particles.The results indicate that methane explosion generated oscillating-pulse loads within perforations.Explosion characteristic parameters increase with increasing initial pressure.Explosion load and bedding orientation significantly influence fracture propagation patterns.As initial pressure increases,the fracture mode transitions from bi-wing to 4–5 radial fractures.In parallel bedding shale,radial fractures noticeably deflect along the bedding surface.Vertical bedding facilitates the development of transverse fractures oriented parallel to the cross-section.Bifurcation-merging of explosioninduced fractures generated CGF.CGF mass and fractal dimension increase,while average particle size decreases with increasing explosion load.This study provides valuable insights into MISEF technology.展开更多
Integrable systems play a crucial role in physics and mathematics.In particular,the traditional(1+1)-dimensional and(2+1)-dimensional integrable systems have received significant attention due to the rarity of integra...Integrable systems play a crucial role in physics and mathematics.In particular,the traditional(1+1)-dimensional and(2+1)-dimensional integrable systems have received significant attention due to the rarity of integrable systems in higher dimensions.Recent studies have shown that abundant higher-dimensional integrable systems can be constructed from(1+1)-dimensional integrable systems by using a deformation algorithm.Here we establish a new(2+1)-dimensional Chen-Lee-Liu(C-L-L)equation using the deformation algorithm from the(1+1)-dimensional C-L-L equation.The new system is integrable with its Lax pair obtained by applying the deformation algorithm to that of the(1+1)-dimension.It is challenging to obtain the exact solutions for the new integrable system because the new system combines both the original C-L-L equation and its reciprocal transformation.The traveling wave solutions are derived in implicit function expression,and some asymmetry peakon solutions are found.展开更多
Fractal theory offers a powerful tool for the precise description and quantification of the complex pore structures in reservoir rocks,crucial for understanding the storage and migration characteristics of media withi...Fractal theory offers a powerful tool for the precise description and quantification of the complex pore structures in reservoir rocks,crucial for understanding the storage and migration characteristics of media within these rocks.Faced with the challenge of calculating the three-dimensional fractal dimensions of rock porosity,this study proposes an innovative computational process that directly calculates the three-dimensional fractal dimensions from a geometric perspective.By employing a composite denoising approach that integrates Fourier transform(FT)and wavelet transform(WT),coupled with multimodal pore extraction techniques such as threshold segmentation,top-hat transformation,and membrane enhancement,we successfully crafted accurate digital rock models.The improved box-counting method was then applied to analyze the voxel data of these digital rocks,accurately calculating the fractal dimensions of the rock pore distribution.Further numerical simulations of permeability experiments were conducted to explore the physical correlations between the rock pore fractal dimensions,porosity,and absolute permeability.The results reveal that rocks with higher fractal dimensions exhibit more complex pore connectivity pathways and a wider,more uneven pore distribution,suggesting that the ideal rock samples should possess lower fractal dimensions and higher effective porosity rates to achieve optimal fluid transmission properties.The methodology and conclusions of this study provide new tools and insights for the quantitative analysis of complex pores in rocks and contribute to the exploration of the fractal transport properties of media within rocks.展开更多
Based on the theory of multibody system dynamics, the spatial kinematics analysis of the Mcpherson independent suspension widely used in the car was carried out. A practical and simpler method was provided to reduce t...Based on the theory of multibody system dynamics, the spatial kinematics analysis of the Mcpherson independent suspension widely used in the car was carried out. A practical and simpler method was provided to reduce the number of the generalized coordinates and constraint functions. By solving the nonlinear equations, the motion of any points in the whole suspension and wheel system can be predicted, including the spatial changes of the wheel alignment parameters which are of great importance to the car performances.展开更多
Some dimensionality reduction （DR） approaches based on support vector machine （SVM） are proposed. But the acquirement of the projection matrix in these approaches only considers the between-class margin based on S...Some dimensionality reduction （DR） approaches based on support vector machine （SVM） are proposed. But the acquirement of the projection matrix in these approaches only considers the between-class margin based on SVM while ignoring the within-class information in data. This paper presents a new DR approach, call- ed the dimensionality reduction based on SVM and LDA （DRSL）. DRSL considers the between-class margins from SVM and LDA, and the within-class compactness from LDA to obtain the projection matrix. As a result, DRSL can realize the combination of the between-class and within-class information and fit the between-class and within-class structures in data. Hence, the obtained projection matrix increases the generalization ability of subsequent classification techniques. Experiments applied to classification techniques show the effectiveness of the proposed method.展开更多
Ray casting algorithm can obtain a better quality image in volume rendering, however, it exists some problems, such as powerful computing capacity and slow rendering speed. How to improve the re-sampled speed is a key...Ray casting algorithm can obtain a better quality image in volume rendering, however, it exists some problems, such as powerful computing capacity and slow rendering speed. How to improve the re-sampled speed is a key to speed up the ray casting algorithm. An algorithm is introduced to reduce matrix computation by matrix transformation characteristics of re-sampling points in a two coordinate system. The projection of 3-D datasets on image plane is adopted to reduce the number of rays. Utilizing boundary box technique avoids the sampling in empty voxel. By extending the Bresenham algorithm to three dimensions, each re-sampling point is calculated. Experimental results show that a two to three-fold improvement in rendering speed using the optimized algorithm, and the similar image quality to traditional algorithm can be achieved. The optimized algorithm can produce the required quality images, thus reducing the total operations and speeding up the volume rendering.展开更多
Two dimensional parabolic stability equations (PSE) are numerically solved using expansions in orthogonal functions in the normal direction.The Chebyshev polynomials approximation,which is a very useful form of ortho...Two dimensional parabolic stability equations (PSE) are numerically solved using expansions in orthogonal functions in the normal direction.The Chebyshev polynomials approximation,which is a very useful form of orthogonal expansions, is applied to solving parabolic stability equations. It is shown that results of great accuracy are effectively obtained.The availability of using Chebyshev approximations in parabolic stability equations is confirmed.展开更多
A very-high color rendering index white organic light-emitting diode(WOLED) based on a simple structure was successfully fabricated. The optimized device exhibits a maximum total efficiency of 13.1 and 5.4 lm/W at 1,0...A very-high color rendering index white organic light-emitting diode(WOLED) based on a simple structure was successfully fabricated. The optimized device exhibits a maximum total efficiency of 13.1 and 5.4 lm/W at 1,000 cd/m2. A peak color rendering index of 90 and a relatively stable color during a wide range of luminance were obtained. In addition, it was demonstrated that the 4,40,400-tri(9-carbazoyl) triphenylamine host influenced strongly the performance of this WOLED.These results may be beneficial to the design of both material and device architecture for high-performance WOLED.展开更多
Principles of dimensional analysis are applied in a new interpretation of penetration of ceramic targets subjected to hypervelocity impact. The analysis results in a power series representation – in terms of inverse ...Principles of dimensional analysis are applied in a new interpretation of penetration of ceramic targets subjected to hypervelocity impact. The analysis results in a power series representation – in terms of inverse velocity – of normalized depth of penetration that reduces to the hydrodynamic solution at high impact velocities. Specifically considered are test data from four literature sources involving penetration of confined thick ceramic targets by tungsten long rod projectiles. The ceramics are AD-995 alumina, aluminum nitride, silicon carbide, and boron carbide.Test data can be accurately represented by the linear form of the power series, whereby the same value of a single fitting parameter applies remarkably well for all four ceramics. Comparison of the present model with others in the literature(e.g., Tate's theory) demonstrates a target resistance stress that depends on impact velocity, linearly in the limiting case. Comparison of the present analysis with recent research involving penetration of thin ceramic tiles at lower typical impact velocities confirms the importance of target properties related to fracture and shear strength at the Hugoniot Elastic Limit(HEL) only in the latter. In contrast, in the former(i.e., hypervelocity and thick target) experiments, the current analysis demonstrates dominant dependence of penetration depth only by target mass density. Such comparisons suggest transitions from microstructure-controlled to density-controlled penetration resistance with increasing impact velocity and ceramic target thickness.Production and hosting by Elsevier B.V. on behalf of China Ordnance Society.展开更多
Low dimensional perovskites have recently attracted much attention due to their vertical growth of crys- talline orientation, excellent film morphology, and long-term humidity, light, and heat stability, How- ever, lo...Low dimensional perovskites have recently attracted much attention due to their vertical growth of crys- talline orientation, excellent film morphology, and long-term humidity, light, and heat stability, How- ever, low dimensional perovskites suffer fl＇om low power conversion efficiency （PCE） with respect to their three dimensional analogues. Therefore, it is imperative to find excellent low-dimensional perovskite materials for improving the PCE. Previous work has demonstrated that bulkier organic molecules, e,g., C6Hs（CH2）2NH3＋ （PEA＋）, CH3（CH2）3NH3＋（n-BAT, iso-BA＋）, C2H4NH3 ＋, and polyethylenimine cations （PEI＋）, play an important role in the formation of low-dimensional perovskites. In this review, we review the recent development of low dimensional perovskites for solar cells application in terms of film preparation, photophysics, and stability of perovskites, as well as the related device structure and physics. We have also discussed the future development of low-dimensional perovskites from materials design, fabri- cation processes, and device structure.展开更多
The frame of text classification system was presented. The high dimensionality in feature space for text classification was studied. The mutual information is a widely used information theoretic measure, in a descript...The frame of text classification system was presented. The high dimensionality in feature space for text classification was studied. The mutual information is a widely used information theoretic measure, in a descriptive way, to measure the stochastic dependency of discrete random variables. The measure method was used as a criterion to reduce high dimensionality of feature vectors in text classification on Web. Feature selections or conversions were performed by using maximum mutual information including linear and non-linear feature conversions. Entropy was used and extended to find right features commendably in pattern recognition systems. Favorable foundation would be established for text classification mining.展开更多
With the rapidly increased concerns in environmental pollution, there have been urgent needs to develop fast, sensitive, low-cost and multiplexed sensing devices for the detection of environmental pollutants. Two-dime...With the rapidly increased concerns in environmental pollution, there have been urgent needs to develop fast, sensitive, low-cost and multiplexed sensing devices for the detection of environmental pollutants. Two-dimensional(2D) nanomaterials hold great promise due to their unique chemical and physical properties, which have been extensively employed to monitor the environmental pollutants combined with different detection techniques. In this review, we summarize recent advances in 2D nanomaterials-based electrochemical sensors for detecting heavy metal ions, organic compounds, pesticides, antibiotics and bacteria. We also discuss perspectives and challenges of 2D nanomaterials in environmental monitoring.展开更多
Transient behavior of three-dimensional semiconductor device with heat conduc- tion is described by a coupled mathematical system of four quasi-linear partial differential equations with initial-boundary value conditi...Transient behavior of three-dimensional semiconductor device with heat conduc- tion is described by a coupled mathematical system of four quasi-linear partial differential equations with initial-boundary value conditions. The electric potential is defined by an ellip- tic equation and it appears in the following three equations via the electric field intensity. The electron concentration and the hole concentration are determined by convection-dominated diffusion equations and the temperature is interpreted by a heat conduction equation. A mixed finite volume element approximation, keeping physical conservation law, is used to get numerical values of the electric potential and the accuracy is improved one order. Two con- centrations and the heat conduction are computed by a fractional step method combined with second-order upwind differences. This method can overcome numerical oscillation, dispersion and decreases computational complexity. Then a three-dimensional problem is solved by computing three successive one-dimensional problems where the method of speedup is used and the computational work is greatly shortened. An optimal second-order error estimate in L2 norm is derived by using prior estimate theory and other special techniques of partial differential equations. This type of mass-conservative parallel method is important and is most valuable in numerical analysis and application of semiconductor device.展开更多
Aiming to deal with the difficult issues of terrain data model simplification and crack disposal,the paper proposed an improved level of detail(LOD)terrain rendering algorithm,in which a variation coefficient of eleva...Aiming to deal with the difficult issues of terrain data model simplification and crack disposal,the paper proposed an improved level of detail(LOD)terrain rendering algorithm,in which a variation coefficient of elevation is introduced to express the undulation of topography.Then the coefficient is used to construct a node evaluation function in the terrain data model simplification step.Furthermore,an edge reduction strategy is combined with the improved restrictive quadtree segmentation to handle the crack problem.The experiment results demonstrated that the proposed method can reduce the amount of rendering triangles and enhance the rendering speed on the premise of ensuring the rendering effect compared with a traditional LOD algorithm.展开更多
Levofloxacin （LOFX）, which is well-known as an antibiotic medicament, was shown to be useful as a 452-nm blue emitter for white organic light-emitting diodes （OLEDs）. In this paper, the fabricated white OLED conta...Levofloxacin （LOFX）, which is well-known as an antibiotic medicament, was shown to be useful as a 452-nm blue emitter for white organic light-emitting diodes （OLEDs）. In this paper, the fabricated white OLED contains a 452-nm blue emitting layer （thickness of 30 nm） with 1 wt% LOFX doped in CBP （4,4＇-bis（carbazol-9-yl）biphenyl） host and a 584-nm orange emitting layer （thickness of 10 nm） with 0.8 wt% DCJTB （4-（dicyanomethylene）-2-tert-butyl-6-（1,1,7,7- tetramethyljulolidin-4-yl-vinyl）-4H-pyran） doped in CBE which are separated by a 20-nm-thick buffer layer of TPBi （2,2＇,2＂-（benzene-1,3,5-triyl）-tri（1-phenyl-lH-benzimidazole）. A high color rendering index （CRI） of 84.5 and CIE chromaticity coordinates of （0.33, 0.32）, which is close to ideal white emission CIE （0.333, 0.333）, are obtained at a bias voltage of 14 V. Taking into account that LOFX is less expensive and the synthesis and purification technologies of LOFX are mature, these results indicate that blue fluorescence emitting LOFX is useful for applications to white OLEDs although the maximum current efficiency and luminance are not high. The present paper is expected to become a milestone to using medical drug materials for OLEDs.展开更多
Objective: To treat humerus fracture with three dimensional pattern and finite element analysis, providing mechanical basis for treating humerus fracture. Methods: Humerus pattern was established based on the CT image...Objective: To treat humerus fracture with three dimensional pattern and finite element analysis, providing mechanical basis for treating humerus fracture. Methods: Humerus pattern was established based on the CT images, and calculation was done by ANSYS5. 6 software. Three dimensional ten-node tetrahedron unit was selected and were divided into 2 729 nodes, 49 041 units. Distribution and amount of axial compression of humerus were analyzed when clip angle was 30°, 45°, 90° between fracture face and axial line with fixed X, Y, Z directions. Results: The distribution of stress was greatly different between fracture face and non fracture face. Stress in fracture part was fairly concentrated with incomplete symmetric distribution around the center of fracture face; Greater stress distributed in the regions 10 mm from fracture face, which was 2-3 times that of other stress regions. Conclusion: Required load must be estimated under various conditions as to select the suitable internal fixation implants during the treatment of humerus fracture, which can provide helpful stress environment for fracture healing.展开更多
Three high dimensional spatial standardization algorithms are used for diffusion tensor image(DTI)registration,and seven kinds of methods are used to evaluate their performances.Firstly,the template used in this paper...Three high dimensional spatial standardization algorithms are used for diffusion tensor image(DTI)registration,and seven kinds of methods are used to evaluate their performances.Firstly,the template used in this paper was obtained by spatial transformation of 16 subjects by means of tensor-based standardization.Then,high dimensional standardization algorithms for diffusion tensor images,including fractional anisotropy(FA)based diffeomorphic registration algorithm,FA based elastic registration algorithm and tensor-based registration algorithm,were performed.Finally,7 kinds of evaluation methods,including normalized standard deviation,dyadic coherence,diffusion cross-correlation,overlap of eigenvalue-eigenvector pairs,Euclidean distance of diffusion tensor,and Euclidean distance of the deviatoric tensor and deviatoric of tensors,were used to qualitatively compare and summarize the above standardization algorithms.Experimental results revealed that the high-dimensional tensor-based standardization algorithms perform well and can maintain the consistency of anatomical structures.展开更多
Wood has no inherent natural resistance against agents of biodegradation. We evaluated the effects of metal bath heat treatment(MBHT) on decay resistance and dimensional stability of Chinese parasol(Firmiana simplex) ...Wood has no inherent natural resistance against agents of biodegradation. We evaluated the effects of metal bath heat treatment(MBHT) on decay resistance and dimensional stability of Chinese parasol(Firmiana simplex) and Chinese fir(Cunninghamia lanceolata) wood. A low melting point alloy was used as heating medium in the treatment of the wood samples at 150, 180, and 210 °C for2, 4, and 8 h. Heat-treated and control samples were exposed to brown rot fungus(Poria placenta) and white rot fungus(Coriolus versicolor) for decay resistance testing and anti-swelling efficiency(ASE). The improved decay resistance with increase temperatures with low mass losses of 7.3 and 7.3% for F. simplex, and 3.9 and 3.6% for C.lanceolata at 210 °C for 8 h against Coriolus versicolor and Poria placenta, respectively. ASE indicated that MBHT contributed to improved dimensional stability of both wood species after treatment. Scanning electron micrograph results indicate that metal bath-treated samples showed strong decay resistance. Therefore, our approach to thermally modify wood should be explored to overcome the energy utilization by using low melting point alloy for the heat treatment of wood.展开更多
This paper reports a new four-dimensional continuous autonomous hyperchaos generated from the Lorenz chaotic system by introducing a nonlinear state feedback controller. Some basic properties of the system are investi...This paper reports a new four-dimensional continuous autonomous hyperchaos generated from the Lorenz chaotic system by introducing a nonlinear state feedback controller. Some basic properties of the system are investigated by means of Lyapunov exponent spectrum and bifurcation diagrams. By numerical simulating, this paper verifies that the four-dimensional system can evolve into periodic, quasi-periodic, chaotic and hyperchaotic behaviours. And the new dynamical system is hyperchaotic in a large region. In comparison with other known hyperchaos, the two positive Lyapunov exponents of the new system are relatively more larger. Thus it has more complex degree.展开更多
In this article, we introduce the two dimensional Mellin transform M4（f）（s,t）, give some properties, establish the Paley-Wiener theorem and Plancherel formula, present the Hausdorff-Young inequality, and find seve...In this article, we introduce the two dimensional Mellin transform M4（f）（s,t）, give some properties, establish the Paley-Wiener theorem and Plancherel formula, present the Hausdorff-Young inequality, and find several applications for the two dimensional Mellin transform.展开更多
基金funded by the National Key Research and Development Program of China(No.2020YFA0711800)the National Science Fund for Distinguished Young Scholars(No.51925404)+2 种基金the National Natural Science Foundation of China(No.12372373)the Postgraduate Research&Practice Innovation Program of Jiangsu Province(No.KYCX24_2909)the Graduate Innovation Program of China University of Mining and Technology(No.2024WLKXJ134)。
文摘Methane in-situ explosion fracturing(MISEF)enhances permeability in shale reservoirs by detonating desorbed methane to generate detonation waves in perforations.Fracture propagation in bedding shale under varying explosion loads remains unclear.In this study,prefabricated perforated shale samples with parallel and vertical bedding are fractured under five distinct explosion loads using a MISEF experimental setup.High-frequency explosion pressure-time curves were monitored within an equivalent perforation,and computed tomography scanning along with three-dimensional reconstruction techniques were used to investigate fracture propagation patterns.Additionally,the formation mechanism and influencing factors of explosion crack-generated fines(CGF)were clarified by analyzing the morphology and statistics of explosion debris particles.The results indicate that methane explosion generated oscillating-pulse loads within perforations.Explosion characteristic parameters increase with increasing initial pressure.Explosion load and bedding orientation significantly influence fracture propagation patterns.As initial pressure increases,the fracture mode transitions from bi-wing to 4–5 radial fractures.In parallel bedding shale,radial fractures noticeably deflect along the bedding surface.Vertical bedding facilitates the development of transverse fractures oriented parallel to the cross-section.Bifurcation-merging of explosioninduced fractures generated CGF.CGF mass and fractal dimension increase,while average particle size decreases with increasing explosion load.This study provides valuable insights into MISEF technology.
基金Project supported by the National Natural Science Foundation of China (Grant Nos.12275144,12235007,and 11975131)K.C.Wong Magna Fund in Ningbo University。
文摘Integrable systems play a crucial role in physics and mathematics.In particular,the traditional(1+1)-dimensional and(2+1)-dimensional integrable systems have received significant attention due to the rarity of integrable systems in higher dimensions.Recent studies have shown that abundant higher-dimensional integrable systems can be constructed from(1+1)-dimensional integrable systems by using a deformation algorithm.Here we establish a new(2+1)-dimensional Chen-Lee-Liu(C-L-L)equation using the deformation algorithm from the(1+1)-dimensional C-L-L equation.The new system is integrable with its Lax pair obtained by applying the deformation algorithm to that of the(1+1)-dimension.It is challenging to obtain the exact solutions for the new integrable system because the new system combines both the original C-L-L equation and its reciprocal transformation.The traveling wave solutions are derived in implicit function expression,and some asymmetry peakon solutions are found.
基金supported by the National Natural Science Foundation of China (Nos.52374078 and 52074043)the Fundamental Research Funds for the Central Universities (No.2023CDJKYJH021)。
文摘Fractal theory offers a powerful tool for the precise description and quantification of the complex pore structures in reservoir rocks,crucial for understanding the storage and migration characteristics of media within these rocks.Faced with the challenge of calculating the three-dimensional fractal dimensions of rock porosity,this study proposes an innovative computational process that directly calculates the three-dimensional fractal dimensions from a geometric perspective.By employing a composite denoising approach that integrates Fourier transform(FT)and wavelet transform(WT),coupled with multimodal pore extraction techniques such as threshold segmentation,top-hat transformation,and membrane enhancement,we successfully crafted accurate digital rock models.The improved box-counting method was then applied to analyze the voxel data of these digital rocks,accurately calculating the fractal dimensions of the rock pore distribution.Further numerical simulations of permeability experiments were conducted to explore the physical correlations between the rock pore fractal dimensions,porosity,and absolute permeability.The results reveal that rocks with higher fractal dimensions exhibit more complex pore connectivity pathways and a wider,more uneven pore distribution,suggesting that the ideal rock samples should possess lower fractal dimensions and higher effective porosity rates to achieve optimal fluid transmission properties.The methodology and conclusions of this study provide new tools and insights for the quantitative analysis of complex pores in rocks and contribute to the exploration of the fractal transport properties of media within rocks.
文摘Based on the theory of multibody system dynamics, the spatial kinematics analysis of the Mcpherson independent suspension widely used in the car was carried out. A practical and simpler method was provided to reduce the number of the generalized coordinates and constraint functions. By solving the nonlinear equations, the motion of any points in the whole suspension and wheel system can be predicted, including the spatial changes of the wheel alignment parameters which are of great importance to the car performances.
文摘Some dimensionality reduction （DR） approaches based on support vector machine （SVM） are proposed. But the acquirement of the projection matrix in these approaches only considers the between-class margin based on SVM while ignoring the within-class information in data. This paper presents a new DR approach, call- ed the dimensionality reduction based on SVM and LDA （DRSL）. DRSL considers the between-class margins from SVM and LDA, and the within-class compactness from LDA to obtain the projection matrix. As a result, DRSL can realize the combination of the between-class and within-class information and fit the between-class and within-class structures in data. Hence, the obtained projection matrix increases the generalization ability of subsequent classification techniques. Experiments applied to classification techniques show the effectiveness of the proposed method.
文摘Ray casting algorithm can obtain a better quality image in volume rendering, however, it exists some problems, such as powerful computing capacity and slow rendering speed. How to improve the re-sampled speed is a key to speed up the ray casting algorithm. An algorithm is introduced to reduce matrix computation by matrix transformation characteristics of re-sampling points in a two coordinate system. The projection of 3-D datasets on image plane is adopted to reduce the number of rays. Utilizing boundary box technique avoids the sampling in empty voxel. By extending the Bresenham algorithm to three dimensions, each re-sampling point is calculated. Experimental results show that a two to three-fold improvement in rendering speed using the optimized algorithm, and the similar image quality to traditional algorithm can be achieved. The optimized algorithm can produce the required quality images, thus reducing the total operations and speeding up the volume rendering.
文摘Two dimensional parabolic stability equations (PSE) are numerically solved using expansions in orthogonal functions in the normal direction.The Chebyshev polynomials approximation,which is a very useful form of orthogonal expansions, is applied to solving parabolic stability equations. It is shown that results of great accuracy are effectively obtained.The availability of using Chebyshev approximations in parabolic stability equations is confirmed.
基金the National Natural Science Foundation of China (Grant Nos.61204087, 61306099)the Guangdong Natural Science Foundation (Grant No. S2012040007003)+2 种基金China Postdoctoral Science Foundation (2013M531841)the Fundamental Research Funds for the Central Universities (2014ZM0003, 2014ZM0034, 2014ZM0037, 2014ZZ0028)the Specialized Research Fund for the Doctoral Program of Higher Education (Grant No. 20120172120008)
文摘A very-high color rendering index white organic light-emitting diode(WOLED) based on a simple structure was successfully fabricated. The optimized device exhibits a maximum total efficiency of 13.1 and 5.4 lm/W at 1,000 cd/m2. A peak color rendering index of 90 and a relatively stable color during a wide range of luminance were obtained. In addition, it was demonstrated that the 4,40,400-tri(9-carbazoyl) triphenylamine host influenced strongly the performance of this WOLED.These results may be beneficial to the design of both material and device architecture for high-performance WOLED.
文摘Principles of dimensional analysis are applied in a new interpretation of penetration of ceramic targets subjected to hypervelocity impact. The analysis results in a power series representation – in terms of inverse velocity – of normalized depth of penetration that reduces to the hydrodynamic solution at high impact velocities. Specifically considered are test data from four literature sources involving penetration of confined thick ceramic targets by tungsten long rod projectiles. The ceramics are AD-995 alumina, aluminum nitride, silicon carbide, and boron carbide.Test data can be accurately represented by the linear form of the power series, whereby the same value of a single fitting parameter applies remarkably well for all four ceramics. Comparison of the present model with others in the literature(e.g., Tate's theory) demonstrates a target resistance stress that depends on impact velocity, linearly in the limiting case. Comparison of the present analysis with recent research involving penetration of thin ceramic tiles at lower typical impact velocities confirms the importance of target properties related to fracture and shear strength at the Hugoniot Elastic Limit(HEL) only in the latter. In contrast, in the former(i.e., hypervelocity and thick target) experiments, the current analysis demonstrates dominant dependence of penetration depth only by target mass density. Such comparisons suggest transitions from microstructure-controlled to density-controlled penetration resistance with increasing impact velocity and ceramic target thickness.Production and hosting by Elsevier B.V. on behalf of China Ordnance Society.
基金financially supported by the National Basic Research Program of China,Fundamental Studies of Perovskite Solar Cells(Grant 2015CB932200)the Natural Science Foundation of China(Grant 51035063)+2 种基金Natural Science Foundation of Jiangsu Province,China(Grants 55135039 and 55135040)Jiangsu Specially-Appointed Professor program(Grant 54907024)Startup from Nanjing Tech University(Grants 3983500160,3983500151,and 44235022)
文摘Low dimensional perovskites have recently attracted much attention due to their vertical growth of crys- talline orientation, excellent film morphology, and long-term humidity, light, and heat stability, How- ever, low dimensional perovskites suffer fl＇om low power conversion efficiency （PCE） with respect to their three dimensional analogues. Therefore, it is imperative to find excellent low-dimensional perovskite materials for improving the PCE. Previous work has demonstrated that bulkier organic molecules, e,g., C6Hs（CH2）2NH3＋ （PEA＋）, CH3（CH2）3NH3＋（n-BAT, iso-BA＋）, C2H4NH3 ＋, and polyethylenimine cations （PEI＋）, play an important role in the formation of low-dimensional perovskites. In this review, we review the recent development of low dimensional perovskites for solar cells application in terms of film preparation, photophysics, and stability of perovskites, as well as the related device structure and physics. We have also discussed the future development of low-dimensional perovskites from materials design, fabri- cation processes, and device structure.
文摘The frame of text classification system was presented. The high dimensionality in feature space for text classification was studied. The mutual information is a widely used information theoretic measure, in a descriptive way, to measure the stochastic dependency of discrete random variables. The measure method was used as a criterion to reduce high dimensionality of feature vectors in text classification on Web. Feature selections or conversions were performed by using maximum mutual information including linear and non-linear feature conversions. Entropy was used and extended to find right features commendably in pattern recognition systems. Favorable foundation would be established for text classification mining.
基金funded by the National Natural Science Foundation of China (61671250,21475064,21373260 and 21305070)the Ministry of Science and Technology of China (2013CB933802)+1 种基金Natural Science Fund for Colleges and Universities in Jiangsu Province(16KJB150032)the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD,YX03002)
文摘With the rapidly increased concerns in environmental pollution, there have been urgent needs to develop fast, sensitive, low-cost and multiplexed sensing devices for the detection of environmental pollutants. Two-dimensional(2D) nanomaterials hold great promise due to their unique chemical and physical properties, which have been extensively employed to monitor the environmental pollutants combined with different detection techniques. In this review, we summarize recent advances in 2D nanomaterials-based electrochemical sensors for detecting heavy metal ions, organic compounds, pesticides, antibiotics and bacteria. We also discuss perspectives and challenges of 2D nanomaterials in environmental monitoring.
基金supported by National Natural Science Foundation of China(11101244,11271231)National Tackling Key Problems Program(20050200069)Doctorate Foundation of the Ministry of Education of China(20030422047)
文摘Transient behavior of three-dimensional semiconductor device with heat conduc- tion is described by a coupled mathematical system of four quasi-linear partial differential equations with initial-boundary value conditions. The electric potential is defined by an ellip- tic equation and it appears in the following three equations via the electric field intensity. The electron concentration and the hole concentration are determined by convection-dominated diffusion equations and the temperature is interpreted by a heat conduction equation. A mixed finite volume element approximation, keeping physical conservation law, is used to get numerical values of the electric potential and the accuracy is improved one order. Two con- centrations and the heat conduction are computed by a fractional step method combined with second-order upwind differences. This method can overcome numerical oscillation, dispersion and decreases computational complexity. Then a three-dimensional problem is solved by computing three successive one-dimensional problems where the method of speedup is used and the computational work is greatly shortened. An optimal second-order error estimate in L2 norm is derived by using prior estimate theory and other special techniques of partial differential equations. This type of mass-conservative parallel method is important and is most valuable in numerical analysis and application of semiconductor device.
基金Supported by the National Natural Science Foundation of China(61363075)the National High Technology Research and Development Program of China(863 Program)(2012AA12A308)the Yue Qi Young Scholars Program of China University of Mining&Technology,Beijing(800015Z1117)
文摘Aiming to deal with the difficult issues of terrain data model simplification and crack disposal,the paper proposed an improved level of detail(LOD)terrain rendering algorithm,in which a variation coefficient of elevation is introduced to express the undulation of topography.Then the coefficient is used to construct a node evaluation function in the terrain data model simplification step.Furthermore,an edge reduction strategy is combined with the improved restrictive quadtree segmentation to handle the crack problem.The experiment results demonstrated that the proposed method can reduce the amount of rendering triangles and enhance the rendering speed on the premise of ensuring the rendering effect compared with a traditional LOD algorithm.
基金supported by the Program for New Century Excellent Talents in University of Ministry of Education of China(Grant No.NCET-13-0927)the International Science&Technology Cooperation Program of China(Grant No.2012DFR50460)+1 种基金the National Natural Science Foundation of China(Grant Nos.21101111 and 61274056)the Shanxi Provincial Key Innovative Research Team in Science and Technology,China(Grant No.2012041011)
文摘Levofloxacin （LOFX）, which is well-known as an antibiotic medicament, was shown to be useful as a 452-nm blue emitter for white organic light-emitting diodes （OLEDs）. In this paper, the fabricated white OLED contains a 452-nm blue emitting layer （thickness of 30 nm） with 1 wt% LOFX doped in CBP （4,4＇-bis（carbazol-9-yl）biphenyl） host and a 584-nm orange emitting layer （thickness of 10 nm） with 0.8 wt% DCJTB （4-（dicyanomethylene）-2-tert-butyl-6-（1,1,7,7- tetramethyljulolidin-4-yl-vinyl）-4H-pyran） doped in CBE which are separated by a 20-nm-thick buffer layer of TPBi （2,2＇,2＂-（benzene-1,3,5-triyl）-tri（1-phenyl-lH-benzimidazole）. A high color rendering index （CRI） of 84.5 and CIE chromaticity coordinates of （0.33, 0.32）, which is close to ideal white emission CIE （0.333, 0.333）, are obtained at a bias voltage of 14 V. Taking into account that LOFX is less expensive and the synthesis and purification technologies of LOFX are mature, these results indicate that blue fluorescence emitting LOFX is useful for applications to white OLEDs although the maximum current efficiency and luminance are not high. The present paper is expected to become a milestone to using medical drug materials for OLEDs.
文摘Objective: To treat humerus fracture with three dimensional pattern and finite element analysis, providing mechanical basis for treating humerus fracture. Methods: Humerus pattern was established based on the CT images, and calculation was done by ANSYS5. 6 software. Three dimensional ten-node tetrahedron unit was selected and were divided into 2 729 nodes, 49 041 units. Distribution and amount of axial compression of humerus were analyzed when clip angle was 30°, 45°, 90° between fracture face and axial line with fixed X, Y, Z directions. Results: The distribution of stress was greatly different between fracture face and non fracture face. Stress in fracture part was fairly concentrated with incomplete symmetric distribution around the center of fracture face; Greater stress distributed in the regions 10 mm from fracture face, which was 2-3 times that of other stress regions. Conclusion: Required load must be estimated under various conditions as to select the suitable internal fixation implants during the treatment of humerus fracture, which can provide helpful stress environment for fracture healing.
基金Supported by the National Key Research and Development Program of China(2016YFC0100300)the National Natural Science Foundation of China(61402371,61771369)+1 种基金the Natural Science Basic Research Plan in Shaanxi Province of China(2017JM6008)the Fundamental Research Funds for the Central Universities of China(3102017zy032,3102018zy020)
文摘Three high dimensional spatial standardization algorithms are used for diffusion tensor image(DTI)registration,and seven kinds of methods are used to evaluate their performances.Firstly,the template used in this paper was obtained by spatial transformation of 16 subjects by means of tensor-based standardization.Then,high dimensional standardization algorithms for diffusion tensor images,including fractional anisotropy(FA)based diffeomorphic registration algorithm,FA based elastic registration algorithm and tensor-based registration algorithm,were performed.Finally,7 kinds of evaluation methods,including normalized standard deviation,dyadic coherence,diffusion cross-correlation,overlap of eigenvalue-eigenvector pairs,Euclidean distance of diffusion tensor,and Euclidean distance of the deviatoric tensor and deviatoric of tensors,were used to qualitatively compare and summarize the above standardization algorithms.Experimental results revealed that the high-dimensional tensor-based standardization algorithms perform well and can maintain the consistency of anatomical structures.
基金financially supported by the Special Scientific Research Fund for Public Service Sectors of Forestry(Grant No.201504603)Science and Technology Projects of Fujian Province(2014NZ003)the National Natural Science Foundation of China(Grant Nos.31370560,31170520)
文摘Wood has no inherent natural resistance against agents of biodegradation. We evaluated the effects of metal bath heat treatment(MBHT) on decay resistance and dimensional stability of Chinese parasol(Firmiana simplex) and Chinese fir(Cunninghamia lanceolata) wood. A low melting point alloy was used as heating medium in the treatment of the wood samples at 150, 180, and 210 °C for2, 4, and 8 h. Heat-treated and control samples were exposed to brown rot fungus(Poria placenta) and white rot fungus(Coriolus versicolor) for decay resistance testing and anti-swelling efficiency(ASE). The improved decay resistance with increase temperatures with low mass losses of 7.3 and 7.3% for F. simplex, and 3.9 and 3.6% for C.lanceolata at 210 °C for 8 h against Coriolus versicolor and Poria placenta, respectively. ASE indicated that MBHT contributed to improved dimensional stability of both wood species after treatment. Scanning electron micrograph results indicate that metal bath-treated samples showed strong decay resistance. Therefore, our approach to thermally modify wood should be explored to overcome the energy utilization by using low melting point alloy for the heat treatment of wood.
基金Project supported by the National Nature Science Foundation of China （Grant No 60574036）, the Specialized Research Fund for the Doctoral Program of China （Grant No 20050055013） and the Program for New Excellent Talents in University of China （NCET）.
文摘This paper reports a new four-dimensional continuous autonomous hyperchaos generated from the Lorenz chaotic system by introducing a nonlinear state feedback controller. Some basic properties of the system are investigated by means of Lyapunov exponent spectrum and bifurcation diagrams. By numerical simulating, this paper verifies that the four-dimensional system can evolve into periodic, quasi-periodic, chaotic and hyperchaotic behaviours. And the new dynamical system is hyperchaotic in a large region. In comparison with other known hyperchaos, the two positive Lyapunov exponents of the new system are relatively more larger. Thus it has more complex degree.
文摘In this article, we introduce the two dimensional Mellin transform M4（f）（s,t）, give some properties, establish the Paley-Wiener theorem and Plancherel formula, present the Hausdorff-Young inequality, and find several applications for the two dimensional Mellin transform.
