Driven by advancements in mobile internet technology,images have become a crucial data medium.Ensuring the security of image information during transmission has thus emerged as an urgent challenge.This study proposes ...Driven by advancements in mobile internet technology,images have become a crucial data medium.Ensuring the security of image information during transmission has thus emerged as an urgent challenge.This study proposes a novel image encryption algorithm specifically designed for grayscale image security.This research introduces a new Cantor diagonal matrix permutation method.The proposed permutation method uses row and column index sequences to control the Cantor diagonal matrix,where the row and column index sequences are generated by a spatiotemporal chaotic system named coupled map lattice(CML).The high initial value sensitivity of the CML system makes the permutation method highly sensitive and secure.Additionally,leveraging fractal theory,this study introduces a chaotic fractal matrix and applies this matrix in the diffusion process.This chaotic fractal matrix exhibits selfsimilarity and irregularity.Using the Cantor diagonal matrix and chaotic fractal matrix,this paper introduces a fast image encryption algorithm involving two diffusion steps and one permutation step.Moreover,the algorithm achieves robust security with only a single encryption round,ensuring high operational efficiency.Experimental results show that the proposed algorithm features an expansive key space,robust security,high sensitivity,high efficiency,and superior statistical properties for the ciphered images.Thus,the proposed algorithm not only provides a practical solution for secure image transmission but also bridges fractal theory with image encryption techniques,thereby opening new research avenues in chaotic cryptography and advancing the development of information security technology.展开更多
Aligning with the ongoing search for quantum spin liquids(QSLs),identifying QSLs in Kitaev magnets has attracted significant research interest during the past decade.Nevertheless,it remains a significant challenge.One...Aligning with the ongoing search for quantum spin liquids(QSLs),identifying QSLs in Kitaev magnets has attracted significant research interest during the past decade.Nevertheless,it remains a significant challenge.One of the major difficulties is that Kitaev QSL is typically fragile to competing interactions such as off-diagonal exchanges,which are ubiquitous in real materials owing to spin-orbit coupling and crystal-field effects.This,in turn,generates many intriguing field-induced novel phases and the thermal Hall effect.In this review,we focus on the interplay between the Kitaev interaction and off-diagonal Γ and Γ′exchange from a numerical perspective.The review discusses certain representative exotic phases such as𝛤spin liquid,nematic ferromagnet,spin-flop phase,and distinct chiral spin states with spontaneous time-reversal symmetry breaking.It also presents quantum phase diagrams of anisotropic Kitaev-Γ chains that exhibit kaleidoscopy for both ordered and disordered phases.展开更多
Current research on localized raceway defects of angular contact ball bearings(ACBB)mainly focuses on assuming that localized raceway defects are cube-shaped defects characterized using a half-sine displacement excita...Current research on localized raceway defects of angular contact ball bearings(ACBB)mainly focuses on assuming that localized raceway defects are cube-shaped defects characterized using a half-sine displacement excitation function.However,the assumption of a cube-shaped defect cannot accurately reflect the morphological characteristics of a localized raceway defect,and the half-sine displacement excitation function cannot be used to accurately describe the relationship between the geometric positions of rolling element and raceway in the region of localized raceway defects.In this study,a comprehensive dynamic model of an ACBB considering a three-dimensional localized raceway defect is established based on the nonlinear Hertz contact theory in conjunction with the outer raceway control theory using the improved Newton–Raphson iteration method.Three localized raceway defect distribution types,namely symmetric,offset,and deflection distributions,are considered.The established model is verified by comparing the results of the proposed model with those of existing literature.The dynamic characteristics of the ACBB were analyzed by investigating the effects of the geometrical size and distribution types on the time-varying contact angles,contact forces,and diagonal stiffness of the ACBB.The investigation results show that the appearance of localized raceway defect leads to the time-varying curves of contact angles,contact forces and diagonal stiffness havingΛ-and V-shaped mutations in some time intervals;The variation tendencies of theΛ-and V-shaped mutations are significant with the increase in defect radial depth H,defect axial width a and angular distanceθ_b.The increase in defect eccentric distance L is beneficial to the rolling elements disengaging from the defect area and it can weaken the influence of localized raceway defect on the time-varying contact and stiffness characteristics of ACBB.The time-varying contact and stiffness characteristics appear to change significantly when the defect deflection angleα_βincrease toα_γ.The results of this study provide a theoretical basis for the fault diagnosis of localized raceway defects in ACBB.展开更多
In this paper, we provide some new necessary and sufficient conditions for generalized diagonally dominant matrices and also obtain some criteria for nongeneralized dominant matrices.
Let DD_0(R)={A∈C^(n×#)||Rea_(ii)Rea_(jj)|≥A_iA_j,i≠j,i,j∈N}.PD_0(R)={A∈C^(n×#)||Rea_(ii)Rea_(kk)|≥A_iA_jA_k,i≠j≠k,i,j,k∈N}. In this paper,we show DD_0(R)PD_0(R),and the conditions under which the nu...Let DD_0(R)={A∈C^(n×#)||Rea_(ii)Rea_(jj)|≥A_iA_j,i≠j,i,j∈N}.PD_0(R)={A∈C^(n×#)||Rea_(ii)Rea_(kk)|≥A_iA_jA_k,i≠j≠k,i,j,k∈N}. In this paper,we show DD_0(R)PD_0(R),and the conditions under which the numbers of eigen vance of A∈PD_0(R)\DD_0(R)are equal to the numbers of a_(ii),i∈N in positive and negative real part respectively.Some couter examples are given which present the condnions can not be omitted.展开更多
In this paper, the nonnull moments and the distributions of the likelihood ratio criterion for testing the equality of diagonal blocks with blockwise independence under certain alternatives have derived.
It is pointed out that the quantum mechanical Hamiltonian of two L-C circuits with mutual-inductance is equivalent to a pair of harmonic oscillators with a kinetic coupling term.We then diagonalize the Hamiltonian.It ...It is pointed out that the quantum mechanical Hamiltonian of two L-C circuits with mutual-inductance is equivalent to a pair of harmonic oscillators with a kinetic coupling term.We then diagonalize the Hamiltonian.It is shown that instantaneously switching on the external sources may result in a two-mode squeezed state of the system,which actually arises from the effect of mutual-inductance.The quantum fluctuation for the case of l_(1)c_(1)=l_(2)c_(2 ) is analysed and it is found that the current fluctuation in the circuits increases with the increment of the mutual-inductance.展开更多
Planar phased-array satellite antennas deform when subjected to external disturbances such as thermal gradients or slewing maneuvers.Such distortion can degrade the coherence of the antenna and must therefore be elimi...Planar phased-array satellite antennas deform when subjected to external disturbances such as thermal gradients or slewing maneuvers.Such distortion can degrade the coherence of the antenna and must therefore be eliminated to maintain performance.To support planar phased-array satellite antennas,a truss with diagonal cables is often applied,generally pretensioned to improve the stiffness of the antenna and maintain the integrity of the structure.A new technique is proposed herein,using the diagonal cables as the actuators for static shape adjustment of the planar phased-array satellite antenna.In this technique,the diagonal cables are not pretensioned;instead,they are slack when the deformation of the antenna is small.When using this technique,there is no need to add redundant control devices,improving the reliability and reducing the mass of the antenna.The finite element method is used to establish a structural model for the satellite antenna,then a method is introduced to select proper diagonal cables and determine the corresponding forces.Numerical simulations of a simplified two-bay satellite antenna are first carried out to validate the proposed technique.Then,a simplified 18-bay antenna is also studied,because spaceborne satellite antennas have inevitably tended to be large in recent years.The numerical simulation results show that the proposed technique can be effectively used to adjust the static shape of planar phased-array satellite antennas,achieving high precision.展开更多
Let Fqbe the finite field,q=p^(k),with p being a prime and k being a positive integer.Let F_(q)^(*)be the multiplicative group of Fq,that is F_(q)^(*)=F_(q){0}.In this paper,by using the Jacobi sums and an analog of H...Let Fqbe the finite field,q=p^(k),with p being a prime and k being a positive integer.Let F_(q)^(*)be the multiplicative group of Fq,that is F_(q)^(*)=F_(q){0}.In this paper,by using the Jacobi sums and an analog of Hasse-Davenport theorem,an explicit formula for the number of solutions of cubic diagonal equation x_(1)^(3)+x_(2)^(3)+…+x_(n)^(3)=c over Fqis given,where c∈F_(q)^(*)and p≡1(mod 3).This extends earlier results.展开更多
We developed a three-dimensional（3D） conjugate gradient inversion algorithm for in-verting magnetotelluric impedance tensor measurements.In order to show the importance of including diagonal components of magnetotel...We developed a three-dimensional（3D） conjugate gradient inversion algorithm for in-verting magnetotelluric impedance tensor measurements.In order to show the importance of including diagonal components of magnetotelluric impedance tensor in 3D inversion,synthetic data were inverted using the 3D conjugate gradient inversion,and the inversion results were compared and analyzed.The results from the 3D inversion of synthetic data indicate that both the off-diagonal and the diagonal components are required in inversions to obtain better inversion results when there are no enough data sites to recover the target resistivity structure.These examples show that lots of information about 3D structure is also contained in the diagonal components;as a result,diagonal components should be in-cluded in 3D inversions.The inversion algorithm was also used to invert the impedance tensor data ac-quired in the Kayabe area in Japan.Inversions with the synthetic and real data demonstrated the va-lidity and practicability of the inversion algorithm.展开更多
In order to overcome the disadvantages of diagonal connection structures that are complex and for which it is difficult to derive the discriminant of the airflow directions of airways, we have applied a multiple regre...In order to overcome the disadvantages of diagonal connection structures that are complex and for which it is difficult to derive the discriminant of the airflow directions of airways, we have applied a multiple regression method to analyze the effect, of changing the rules of mine airflows, on the stability of a mine ventilation system. The amount of air （ Qj ） is determined for the major airway and an optimum regression equation was derived for Qi as a function of the independent variable （ Ri ）, i.e., the venti- lation resistance between different airways. Therefore, corresponding countermeasures are proposed according to the changes in airflows. The calculated results agree very well with our practical situation, indicating that multiple regression analysis is simple, quick and practical and is therefore an effective method to analyze the stability of mine ventilation systems.展开更多
The derivation of a diagonally loaded sample-matrix inversion （LSMI） algorithm on the busis of inverse matrix recursion （i.e.LSMI-IMR algorithm） is conducted by reconstructing the recursive formulation of covarian...The derivation of a diagonally loaded sample-matrix inversion （LSMI） algorithm on the busis of inverse matrix recursion （i.e.LSMI-IMR algorithm） is conducted by reconstructing the recursive formulation of covariance matrix. For the new algorithm, diagonal loading is by setting initial inverse matrix without any addition of computation. In addition, a corresponding improved recursive algorithm is presented, which is low computational complexity. This eliminates the complex multiplications of the scalar coefficient and updating matrix, resulting in significant computational savings. Simulations show that the LSMI-IMR algorithm is valid.展开更多
A study of bispectral analysis in gearbox condition monitoring is presented.The theory of bispectrum and quadratic phase coupling (QPC) is first introduced, and then equationsfor computing bispectrum slices are obtain...A study of bispectral analysis in gearbox condition monitoring is presented.The theory of bispectrum and quadratic phase coupling (QPC) is first introduced, and then equationsfor computing bispectrum slices are obtained. To meet the needs of online monitoring, a simplifiedmethod of computing bispectrum diagonal slice is adopted. Industrial gearbox vibration signalsmeasured from normal and tooth cracked conditions are analyzed using the above method. Experimentsresults indicate that bispectrum can effectively suppress the additive Gaussian noise andchracterize the QPC phenomenon. It is also shown that the 1-D bispectrum diagonal slice can capturethe non-Gaussian and nonlinear feature of gearbox vibration when crack occurred, hence, this methodcan be employed to gearbox real time monitoring and early diagnosis.展开更多
6016-T4 aluminum alloy and DP490 steel were systematically tested under 24 proportional loading paths,including uniaxial tensile tests with a 15°increment,uniaxial compressive and simple shear tests with a 45...6016-T4 aluminum alloy and DP490 steel were systematically tested under 24 proportional loading paths,including uniaxial tensile tests with a 15°increment,uniaxial compressive and simple shear tests with a 45°increment,and biaxial tensile tests using cruciform specimens.Cruciform specimens in the rolling/transverse and 45°/135°sampling directions were tested with seven and four different stress ra-tios,respectively.The normal and diagonal planes plastic work contours and the yield stresses under uniaxial tension and compression were measured to investigate the anisotropic yield.Meanwhile,the normal and diagonal planes directions of plastic strain rate and the rα-values under uniaxial tension and compression were characterized to confirm the plastic flow.Several existing asymmetric yield crite-ria under the associated and non-associated flow rules were comprehensively evaluated to describe the asymmetric plastic anisotropy of 6016-T4 aluminum alloy and DP490 steel.The results suggest that in the investigated yield criteria,the non-associated models can predict the tension and compression asym-metry of materials more accurately than the associated models,and the function of stress triaxiality can more effectively describe the asymmetric yield behavior than the first stress invariant.In addition,the pure shear stress states are helpful in assessing the validity and applicability of advanced asymmetric yield stress functions,and the inspection of diagonal plane plastic work contours containing more pure shear stress states should prioritized over that of normal plane plastic work contours.The evaluation of plastic potential functions should not only consider the prediction accuracy of the normal plane di-rections of plastic strain rate,but also further check the diagonal plane directions of plastic strain rate.Expressing mechanical properties as a function of equivalent plastic strain to calibrate parameters of the yield criterion allows the continuous capture of anisotropic evolution of the asymmetric yield surface and the changes in the asymmetric plastic potential surface.展开更多
With a focus on an industrial multivariable system, two subsystems including the flow and the level outputs are analysed and controlled, which have applicability in both real and academic environments. In such a case,...With a focus on an industrial multivariable system, two subsystems including the flow and the level outputs are analysed and controlled, which have applicability in both real and academic environments. In such a case, at first, each subsystem is distinctively represented by its model, since the outcomes point out that the chosen models have the same behavior as corresponding ones. Then, the industrial multivariable system and its presentation are achieved in line with the integration of these subsystems, since the interaction between them can not actually be ignored. To analyze the interaction presented, the Gershgorin bands need to be acquired, where the results are used to modify the system parameters to appropriate values. Subsequently, in the view of modeling results, the control concept in two different techniques including sequential loop closing control(SLCC) scheme and diagonal dominance control(DDC) schemes is proposed to implement on the system through the Profibus network, as long as the OPC(OLE for process control) server is utilized to communicate between the control schemes presented and the multivariable system. The real test scenarios are carried out and the corresponding outcomes in their present forms are acquired. In the same way, the proposed control schemes results are compared with each other, where the real consequences verify the validity of them in the field of the presented industrial multivariable system control.展开更多
Beer fermentation process is a complex biochemical reaction process.It is the most important to control temperature of the wort in fermentation tank in accordance with the beer fermentation temperature curve so as to ...Beer fermentation process is a complex biochemical reaction process.It is the most important to control temperature of the wort in fermentation tank in accordance with the beer fermentation temperature curve so as to ensure the completion of fermentation.The controlled object is characterized by large inertia,long time delay and mutual coupling of three temperature areas.Based on this,a temperature control method for beer fermentation system is designed.Using digital incremental proportion integration differentiation （PID） control algorithm,the controlled quantity is transmitted to the controlled object after diagonal matrix decoupling.This simulation system can be completed in laboratory using VB and Kingview software,so it has the features of good security and low cost.It is very suitable for experimental teaching.展开更多
This study was conducted to analyze the effect of joint type, and numbers and types of dovetail keys on diagonal tension and compression performance of corner joints in a furniture frame. Joint members were cut from w...This study was conducted to analyze the effect of joint type, and numbers and types of dovetail keys on diagonal tension and compression performance of corner joints in a furniture frame. Joint members were cut from white fir lumber. Butted and mitered joints were constructed with one and two dovetail key（s） with butterfly and H shapes. Joints were glued by polyvinyl acetate （PVAc） and cynoacrylate （CA）. Compression capacity of joints was higher than diagonal tension. Mitered joints were stronger than butted ones. Butterfly dovetail keys were superior to H shape keys. Double keys performed better than single key. Experimental joints glued with PVAc were stronger than those glued with CA glue and control specimens. In terms of strength, butterfly dovetailed joints were comparable with doweled joints.展开更多
In order to enhance the robustness and contrast in the minimum variance(MV) beamformer, adaptive diagonal loading method was proposed. The conventional diagonal loading technique has already been used in the MV beamfo...In order to enhance the robustness and contrast in the minimum variance(MV) beamformer, adaptive diagonal loading method was proposed. The conventional diagonal loading technique has already been used in the MV beamformer, but has the drawback that its level is specified by predefined parameter and without consideration of input-data. To alleviate this problem, the level of diagonal loading was computed appropriately and automatically from the given data by shrinkage method in the proposed adaptive diagonal loaded beamformer. The performance of the proposed beamformer was tested on the simulated point target and cyst phantom was obtained using Field II. In the point target simulation, it is shown that the proposed method has higher lateral resolution than the conventional delay-and-sum beamformer and could be more robust in estimating the amplitude peak than the MV beamformer when acoustic velocity error exists. In the cyst phantom simulation, the proposed beamformer has shown that it achieves an improvement in contrast ratio and without distorting the edges of cyst.展开更多
A DRNN (diagonal recurrent neural network) and its RPE (recurrent prediction error) learning algorithm are proposed in this paper .Using of the simple structure of DRNN can reduce the capacity of calculation. The prin...A DRNN (diagonal recurrent neural network) and its RPE (recurrent prediction error) learning algorithm are proposed in this paper .Using of the simple structure of DRNN can reduce the capacity of calculation. The principle of RPE learning algorithm is to adjust weights along the direction of Gauss-Newton. Meanwhile, it is unnecessary to calculate the second local derivative and the inverse matrixes, whose unbiasedness is proved. With application to the extremely short time prediction of large ship pitch, satisfactory results are obtained. Prediction effect of this algorithm is compared with that of auto-regression and periodical diagram method, and comparison results show that the proposed algorithm is feasible.展开更多
基金supported by the National Natural Science Foundation of China(62376106)The Science and Technology Development Plan of Jilin Province(20250102212JC).
文摘Driven by advancements in mobile internet technology,images have become a crucial data medium.Ensuring the security of image information during transmission has thus emerged as an urgent challenge.This study proposes a novel image encryption algorithm specifically designed for grayscale image security.This research introduces a new Cantor diagonal matrix permutation method.The proposed permutation method uses row and column index sequences to control the Cantor diagonal matrix,where the row and column index sequences are generated by a spatiotemporal chaotic system named coupled map lattice(CML).The high initial value sensitivity of the CML system makes the permutation method highly sensitive and secure.Additionally,leveraging fractal theory,this study introduces a chaotic fractal matrix and applies this matrix in the diffusion process.This chaotic fractal matrix exhibits selfsimilarity and irregularity.Using the Cantor diagonal matrix and chaotic fractal matrix,this paper introduces a fast image encryption algorithm involving two diffusion steps and one permutation step.Moreover,the algorithm achieves robust security with only a single encryption round,ensuring high operational efficiency.Experimental results show that the proposed algorithm features an expansive key space,robust security,high sensitivity,high efficiency,and superior statistical properties for the ciphered images.Thus,the proposed algorithm not only provides a practical solution for secure image transmission but also bridges fractal theory with image encryption techniques,thereby opening new research avenues in chaotic cryptography and advancing the development of information security technology.
基金supported by the National Program on Key Research Projects(Grant No.MOST2022YFA1402700)the National Natural Science Foundation of China(Grant Nos.12304176,12274187,12247183,and 12247101)+1 种基金the Natural Science Foundation of Jiangsu Province(Grant No.BK20220876)partially supported by the High-Performance Computing Platform of Nanjing University of Aeronautics and Astronautics。
文摘Aligning with the ongoing search for quantum spin liquids(QSLs),identifying QSLs in Kitaev magnets has attracted significant research interest during the past decade.Nevertheless,it remains a significant challenge.One of the major difficulties is that Kitaev QSL is typically fragile to competing interactions such as off-diagonal exchanges,which are ubiquitous in real materials owing to spin-orbit coupling and crystal-field effects.This,in turn,generates many intriguing field-induced novel phases and the thermal Hall effect.In this review,we focus on the interplay between the Kitaev interaction and off-diagonal Γ and Γ′exchange from a numerical perspective.The review discusses certain representative exotic phases such as𝛤spin liquid,nematic ferromagnet,spin-flop phase,and distinct chiral spin states with spontaneous time-reversal symmetry breaking.It also presents quantum phase diagrams of anisotropic Kitaev-Γ chains that exhibit kaleidoscopy for both ordered and disordered phases.
基金Supported by National Natural Science Foundation of China(Grant No.52075554)Hunan Provincial Natural Science Foundation of China(Grant No.2022JJ20070)+1 种基金Innovation-Driven Research Program of Central South University of China(Grant No.2023CXQD049)State Key Laboratory of High Performance Complex Manufacturing of China(Grant No.ZZYJKT2021-07)。
文摘Current research on localized raceway defects of angular contact ball bearings(ACBB)mainly focuses on assuming that localized raceway defects are cube-shaped defects characterized using a half-sine displacement excitation function.However,the assumption of a cube-shaped defect cannot accurately reflect the morphological characteristics of a localized raceway defect,and the half-sine displacement excitation function cannot be used to accurately describe the relationship between the geometric positions of rolling element and raceway in the region of localized raceway defects.In this study,a comprehensive dynamic model of an ACBB considering a three-dimensional localized raceway defect is established based on the nonlinear Hertz contact theory in conjunction with the outer raceway control theory using the improved Newton–Raphson iteration method.Three localized raceway defect distribution types,namely symmetric,offset,and deflection distributions,are considered.The established model is verified by comparing the results of the proposed model with those of existing literature.The dynamic characteristics of the ACBB were analyzed by investigating the effects of the geometrical size and distribution types on the time-varying contact angles,contact forces,and diagonal stiffness of the ACBB.The investigation results show that the appearance of localized raceway defect leads to the time-varying curves of contact angles,contact forces and diagonal stiffness havingΛ-and V-shaped mutations in some time intervals;The variation tendencies of theΛ-and V-shaped mutations are significant with the increase in defect radial depth H,defect axial width a and angular distanceθ_b.The increase in defect eccentric distance L is beneficial to the rolling elements disengaging from the defect area and it can weaken the influence of localized raceway defect on the time-varying contact and stiffness characteristics of ACBB.The time-varying contact and stiffness characteristics appear to change significantly when the defect deflection angleα_βincrease toα_γ.The results of this study provide a theoretical basis for the fault diagnosis of localized raceway defects in ACBB.
文摘In this paper, we provide some new necessary and sufficient conditions for generalized diagonally dominant matrices and also obtain some criteria for nongeneralized dominant matrices.
文摘Let DD_0(R)={A∈C^(n×#)||Rea_(ii)Rea_(jj)|≥A_iA_j,i≠j,i,j∈N}.PD_0(R)={A∈C^(n×#)||Rea_(ii)Rea_(kk)|≥A_iA_jA_k,i≠j≠k,i,j,k∈N}. In this paper,we show DD_0(R)PD_0(R),and the conditions under which the numbers of eigen vance of A∈PD_0(R)\DD_0(R)are equal to the numbers of a_(ii),i∈N in positive and negative real part respectively.Some couter examples are given which present the condnions can not be omitted.
文摘In this paper, the nonnull moments and the distributions of the likelihood ratio criterion for testing the equality of diagonal blocks with blockwise independence under certain alternatives have derived.
基金Supported by the National Natural Science Foundation of China under Grant No.19574045。
文摘It is pointed out that the quantum mechanical Hamiltonian of two L-C circuits with mutual-inductance is equivalent to a pair of harmonic oscillators with a kinetic coupling term.We then diagonalize the Hamiltonian.It is shown that instantaneously switching on the external sources may result in a two-mode squeezed state of the system,which actually arises from the effect of mutual-inductance.The quantum fluctuation for the case of l_(1)c_(1)=l_(2)c_(2 ) is analysed and it is found that the current fluctuation in the circuits increases with the increment of the mutual-inductance.
基金the National Natural Science Foundation of China(Grant 11772187)the research project of the Key Laboratory of Infrared System Detection and Imaging Technology of the Chinese Academy of Sciences(Grant CASIR201702)the Natural Science Foundation of Shanghai(Grant 16ZRi436200).
文摘Planar phased-array satellite antennas deform when subjected to external disturbances such as thermal gradients or slewing maneuvers.Such distortion can degrade the coherence of the antenna and must therefore be eliminated to maintain performance.To support planar phased-array satellite antennas,a truss with diagonal cables is often applied,generally pretensioned to improve the stiffness of the antenna and maintain the integrity of the structure.A new technique is proposed herein,using the diagonal cables as the actuators for static shape adjustment of the planar phased-array satellite antenna.In this technique,the diagonal cables are not pretensioned;instead,they are slack when the deformation of the antenna is small.When using this technique,there is no need to add redundant control devices,improving the reliability and reducing the mass of the antenna.The finite element method is used to establish a structural model for the satellite antenna,then a method is introduced to select proper diagonal cables and determine the corresponding forces.Numerical simulations of a simplified two-bay satellite antenna are first carried out to validate the proposed technique.Then,a simplified 18-bay antenna is also studied,because spaceborne satellite antennas have inevitably tended to be large in recent years.The numerical simulation results show that the proposed technique can be effectively used to adjust the static shape of planar phased-array satellite antennas,achieving high precision.
基金Supported by the Natural Science Foundation of Henan Province(232300420123)the National Natural Science Foundation of China(12026224)the Research Center of Mathematics and Applied Mathematics,Nanyang Institute of Technology。
文摘Let Fqbe the finite field,q=p^(k),with p being a prime and k being a positive integer.Let F_(q)^(*)be the multiplicative group of Fq,that is F_(q)^(*)=F_(q){0}.In this paper,by using the Jacobi sums and an analog of Hasse-Davenport theorem,an explicit formula for the number of solutions of cubic diagonal equation x_(1)^(3)+x_(2)^(3)+…+x_(n)^(3)=c over Fqis given,where c∈F_(q)^(*)and p≡1(mod 3).This extends earlier results.
基金supported by the National Natural Science Foundation of China (Nos. 40774029, 41004028)the Special Fund for Basic Scientific Research of Central Colleges (No. 2010ZY53)the Program for New Century Excellent Talents in University (NCET)
文摘We developed a three-dimensional（3D） conjugate gradient inversion algorithm for in-verting magnetotelluric impedance tensor measurements.In order to show the importance of including diagonal components of magnetotelluric impedance tensor in 3D inversion,synthetic data were inverted using the 3D conjugate gradient inversion,and the inversion results were compared and analyzed.The results from the 3D inversion of synthetic data indicate that both the off-diagonal and the diagonal components are required in inversions to obtain better inversion results when there are no enough data sites to recover the target resistivity structure.These examples show that lots of information about 3D structure is also contained in the diagonal components;as a result,diagonal components should be in-cluded in 3D inversions.The inversion algorithm was also used to invert the impedance tensor data ac-quired in the Kayabe area in Japan.Inversions with the synthetic and real data demonstrated the va-lidity and practicability of the inversion algorithm.
基金Project F010206 supported by the National Natural Science Foundation of China
文摘In order to overcome the disadvantages of diagonal connection structures that are complex and for which it is difficult to derive the discriminant of the airflow directions of airways, we have applied a multiple regression method to analyze the effect, of changing the rules of mine airflows, on the stability of a mine ventilation system. The amount of air （ Qj ） is determined for the major airway and an optimum regression equation was derived for Qi as a function of the independent variable （ Ri ）, i.e., the venti- lation resistance between different airways. Therefore, corresponding countermeasures are proposed according to the changes in airflows. The calculated results agree very well with our practical situation, indicating that multiple regression analysis is simple, quick and practical and is therefore an effective method to analyze the stability of mine ventilation systems.
文摘The derivation of a diagonally loaded sample-matrix inversion （LSMI） algorithm on the busis of inverse matrix recursion （i.e.LSMI-IMR algorithm） is conducted by reconstructing the recursive formulation of covariance matrix. For the new algorithm, diagonal loading is by setting initial inverse matrix without any addition of computation. In addition, a corresponding improved recursive algorithm is presented, which is low computational complexity. This eliminates the complex multiplications of the scalar coefficient and updating matrix, resulting in significant computational savings. Simulations show that the LSMI-IMR algorithm is valid.
基金This project is supported by 95 Pan Deng Program of China (No.PD952l908) National Key Basic Research Special Foundation of China (No.Gl998020320)Provincial Natural Science Foundation of Hubei, China (No.2000J125)
文摘A study of bispectral analysis in gearbox condition monitoring is presented.The theory of bispectrum and quadratic phase coupling (QPC) is first introduced, and then equationsfor computing bispectrum slices are obtained. To meet the needs of online monitoring, a simplifiedmethod of computing bispectrum diagonal slice is adopted. Industrial gearbox vibration signalsmeasured from normal and tooth cracked conditions are analyzed using the above method. Experimentsresults indicate that bispectrum can effectively suppress the additive Gaussian noise andchracterize the QPC phenomenon. It is also shown that the 1-D bispectrum diagonal slice can capturethe non-Gaussian and nonlinear feature of gearbox vibration when crack occurred, hence, this methodcan be employed to gearbox real time monitoring and early diagnosis.
基金the Promotion China Ph.D.Pro-gram of BMW Brilliance Automotive Ltd.and Beijing Municipal Ed-ucation Commission and Beijing Municipal Natural Science Foun-dation(No.KZ200010009041)for financial support and KOBELCO and TAGAL for providing commercial automotive sheets.
文摘6016-T4 aluminum alloy and DP490 steel were systematically tested under 24 proportional loading paths,including uniaxial tensile tests with a 15°increment,uniaxial compressive and simple shear tests with a 45°increment,and biaxial tensile tests using cruciform specimens.Cruciform specimens in the rolling/transverse and 45°/135°sampling directions were tested with seven and four different stress ra-tios,respectively.The normal and diagonal planes plastic work contours and the yield stresses under uniaxial tension and compression were measured to investigate the anisotropic yield.Meanwhile,the normal and diagonal planes directions of plastic strain rate and the rα-values under uniaxial tension and compression were characterized to confirm the plastic flow.Several existing asymmetric yield crite-ria under the associated and non-associated flow rules were comprehensively evaluated to describe the asymmetric plastic anisotropy of 6016-T4 aluminum alloy and DP490 steel.The results suggest that in the investigated yield criteria,the non-associated models can predict the tension and compression asym-metry of materials more accurately than the associated models,and the function of stress triaxiality can more effectively describe the asymmetric yield behavior than the first stress invariant.In addition,the pure shear stress states are helpful in assessing the validity and applicability of advanced asymmetric yield stress functions,and the inspection of diagonal plane plastic work contours containing more pure shear stress states should prioritized over that of normal plane plastic work contours.The evaluation of plastic potential functions should not only consider the prediction accuracy of the normal plane di-rections of plastic strain rate,but also further check the diagonal plane directions of plastic strain rate.Expressing mechanical properties as a function of equivalent plastic strain to calibrate parameters of the yield criterion allows the continuous capture of anisotropic evolution of the asymmetric yield surface and the changes in the asymmetric plastic potential surface.
文摘With a focus on an industrial multivariable system, two subsystems including the flow and the level outputs are analysed and controlled, which have applicability in both real and academic environments. In such a case, at first, each subsystem is distinctively represented by its model, since the outcomes point out that the chosen models have the same behavior as corresponding ones. Then, the industrial multivariable system and its presentation are achieved in line with the integration of these subsystems, since the interaction between them can not actually be ignored. To analyze the interaction presented, the Gershgorin bands need to be acquired, where the results are used to modify the system parameters to appropriate values. Subsequently, in the view of modeling results, the control concept in two different techniques including sequential loop closing control(SLCC) scheme and diagonal dominance control(DDC) schemes is proposed to implement on the system through the Profibus network, as long as the OPC(OLE for process control) server is utilized to communicate between the control schemes presented and the multivariable system. The real test scenarios are carried out and the corresponding outcomes in their present forms are acquired. In the same way, the proposed control schemes results are compared with each other, where the real consequences verify the validity of them in the field of the presented industrial multivariable system control.
基金Shandong Province Department of Education Science and Technology Program(No.J05C11)
文摘Beer fermentation process is a complex biochemical reaction process.It is the most important to control temperature of the wort in fermentation tank in accordance with the beer fermentation temperature curve so as to ensure the completion of fermentation.The controlled object is characterized by large inertia,long time delay and mutual coupling of three temperature areas.Based on this,a temperature control method for beer fermentation system is designed.Using digital incremental proportion integration differentiation （PID） control algorithm,the controlled quantity is transmitted to the controlled object after diagonal matrix decoupling.This simulation system can be completed in laboratory using VB and Kingview software,so it has the features of good security and low cost.It is very suitable for experimental teaching.
文摘This study was conducted to analyze the effect of joint type, and numbers and types of dovetail keys on diagonal tension and compression performance of corner joints in a furniture frame. Joint members were cut from white fir lumber. Butted and mitered joints were constructed with one and two dovetail key（s） with butterfly and H shapes. Joints were glued by polyvinyl acetate （PVAc） and cynoacrylate （CA）. Compression capacity of joints was higher than diagonal tension. Mitered joints were stronger than butted ones. Butterfly dovetail keys were superior to H shape keys. Double keys performed better than single key. Experimental joints glued with PVAc were stronger than those glued with CA glue and control specimens. In terms of strength, butterfly dovetailed joints were comparable with doweled joints.
基金Project(2013GZX0147-3)supported by the Science and Technology Pillar Program of Sichuan Province,China
文摘In order to enhance the robustness and contrast in the minimum variance(MV) beamformer, adaptive diagonal loading method was proposed. The conventional diagonal loading technique has already been used in the MV beamformer, but has the drawback that its level is specified by predefined parameter and without consideration of input-data. To alleviate this problem, the level of diagonal loading was computed appropriately and automatically from the given data by shrinkage method in the proposed adaptive diagonal loaded beamformer. The performance of the proposed beamformer was tested on the simulated point target and cyst phantom was obtained using Field II. In the point target simulation, it is shown that the proposed method has higher lateral resolution than the conventional delay-and-sum beamformer and could be more robust in estimating the amplitude peak than the MV beamformer when acoustic velocity error exists. In the cyst phantom simulation, the proposed beamformer has shown that it achieves an improvement in contrast ratio and without distorting the edges of cyst.
文摘A DRNN (diagonal recurrent neural network) and its RPE (recurrent prediction error) learning algorithm are proposed in this paper .Using of the simple structure of DRNN can reduce the capacity of calculation. The principle of RPE learning algorithm is to adjust weights along the direction of Gauss-Newton. Meanwhile, it is unnecessary to calculate the second local derivative and the inverse matrixes, whose unbiasedness is proved. With application to the extremely short time prediction of large ship pitch, satisfactory results are obtained. Prediction effect of this algorithm is compared with that of auto-regression and periodical diagram method, and comparison results show that the proposed algorithm is feasible.
