Single-pixel imaging(SPI)can transform 2D or 3D image data into 1D light signals,which offers promising prospects for image compression and transmission.However,during data communication these light signals in public ...Single-pixel imaging(SPI)can transform 2D or 3D image data into 1D light signals,which offers promising prospects for image compression and transmission.However,during data communication these light signals in public channels will easily draw the attention of eavesdroppers.Here,we introduce an efficient encryption method for SPI data transmission that uses the 3D Arnold transformation to directly disrupt 1D single-pixel light signals and utilizes the elliptic curve encryption algorithm for key transmission.This encryption scheme immediately employs Hadamard patterns to illuminate the scene and then utilizes the 3D Arnold transformation to permutate the 1D light signal of single-pixel detection.Then the transformation parameters serve as the secret key,while the security of key exchange is guaranteed by an elliptic curve-based key exchange mechanism.Compared with existing encryption schemes,both computer simulations and optical experiments have been conducted to demonstrate that the proposed technique not only enhances the security of encryption but also eliminates the need for complicated pattern scrambling rules.Additionally,this approach solves the problem of secure key transmission,thus ensuring the security of information and the quality of the decrypted images.展开更多
The transformation behavior of Ni Ti Nb based alloys was analysed.The absence of R phase transformation in these alloys is related to the stress field in the NiTi matrix.The thermal mismatch stress was calculated by...The transformation behavior of Ni Ti Nb based alloys was analysed.The absence of R phase transformation in these alloys is related to the stress field in the NiTi matrix.The thermal mismatch stress was calculated by the Eshelby method in Ni Ti Nb alloys.The results show that the mean matrix elastic stress field is isostatic tensile,there is no preferred stress in [111] B 2 direction.The mean matrix stress from the thermal misfit between NiTi matrix and β Nb particle is too small to induce dislocations.All the factors tend to inhibit R phase transformation.展开更多
Monocular 3D object detection is challenging due to the lack of accurate depth information.Some methods estimate the pixel-wise depth maps from off-the-shelf depth estimators and then use them as an additional input t...Monocular 3D object detection is challenging due to the lack of accurate depth information.Some methods estimate the pixel-wise depth maps from off-the-shelf depth estimators and then use them as an additional input to augment the RGB images.Depth-based methods attempt to convert estimated depth maps to pseudo-LiDAR and then use LiDAR-based object detectors or focus on the perspective of image and depth fusion learning.However,they demonstrate limited performance and efficiency as a result of depth inaccuracy and complex fusion mode with convolutions.Different from these approaches,our proposed depth-guided vision transformer with a normalizing flows(NF-DVT)network uses normalizing flows to build priors in depth maps to achieve more accurate depth information.Then we develop a novel Swin-Transformer-based backbone with a fusion module to process RGB image patches and depth map patches with two separate branches and fuse them using cross-attention to exchange information with each other.Furthermore,with the help of pixel-wise relative depth values in depth maps,we develop new relative position embeddings in the cross-attention mechanism to capture more accurate sequence ordering of input tokens.Our method is the first Swin-Transformer-based backbone architecture for monocular 3D object detection.The experimental results on the KITTI and the challenging Waymo Open datasets show the effectiveness of our proposed method and superior performance over previous counterparts.展开更多
Three transformation models (Bursa-Wolf, Molodensky, and WTUSM) are generally used between two data systems transformation. The linear models are used when the rotation angles are small; however, when the rotation a...Three transformation models (Bursa-Wolf, Molodensky, and WTUSM) are generally used between two data systems transformation. The linear models are used when the rotation angles are small; however, when the rotation angles get bigger, model errors will be produced. In this paper, we present a method with three main terms:① the traditional rotation angles θ,φ,ψ are substituted with a,b,c which are three respective values in the anti-symmetrical or Lodrigues matrix; ② directly and accurately calculating the formula of seven parameters in any value of rotation angles; and ③ a corresponding adjustment model is established. This method does not use the triangle function. Instead it uses addition, subtraction, multiplication and division, and the complexity of the equation is reduced, making the calculation easy and quick.展开更多
Some problems connect ed with production of new light-weight filler type are considered for sandwich layers. Constructively, the filler is the folded structure that can be developed on a plane. This feature makes it...Some problems connect ed with production of new light-weight filler type are considered for sandwich layers. Constructively, the filler is the folded structure that can be developed on a plane. This feature makes it possible to produce the filler by isometric t ransformation of thin sheet through local bending without material stretching.Th e main difficulty is that the bending must be carried out along all lines of com plex-shaped marking-out at a time. The problem of shaping can be solved by use of the original shaping device that can be transformed in operation. The herein -presented technology of production makes it possible to fabricate parts with d eep relief using a wide gamut of different materials even as the thin-sheet met al alloys and paper.展开更多
Measurements of electrical resistivity, X-ray diffraction, and tensile test at room temperature and ?196°C were performed to investigate the effects of Al addition substituting Ni on the phase transformation beh...Measurements of electrical resistivity, X-ray diffraction, and tensile test at room temperature and ?196°C were performed to investigate the effects of Al addition substituting Ni on the phase transformation behaviors, the mechanical properties, and the shape memory effects of Ti50Ni47Fe2Al1 and Ti50Ni46.5Fe2.5Al1 alloys. It is found that 1at% Al addition dramatically decreases the martensitic start transformation temperature and expands the transformation temperature range of R-phase for TiNiFeAl alloys. The results of tensile test indicate that 1at% Al improves the yield strength of Ti50Ni47Fe2Al1 and Ti50Ni46.5Fe2.5Al1 alloys by 40% and 64%, but de- creases the plasticity to 11% and 12% from 26% and 27% respectively. Moreover, excellent shape memory effect of 6.6% and 7.5% were found in Ti50Ni47Fe2Al1 and Ti50Ni46.5Fe2.5Al1 alloys, which results from the stress-induced martensite transformation from the R-phase.展开更多
Structure and magnetostriction of Dy1-Pr_x Fe_2 (0≤x≤0.5), Dy_0.6Pr_0.4(Fe_1-_yT_y)_2 (0≤y≤0.6), and Tb_1-z Pr_z(Fe_0.4Co_0.6)_2 (0≤z≤1.0) alloys (T=Co, Ni) have been investigated. It is found that the matrix of...Structure and magnetostriction of Dy1-Pr_x Fe_2 (0≤x≤0.5), Dy_0.6Pr_0.4(Fe_1-_yT_y)_2 (0≤y≤0.6), and Tb_1-z Pr_z(Fe_0.4Co_0.6)_2 (0≤z≤1.0) alloys (T=Co, Ni) have been investigated. It is found that the matrix of the alloys Dy_1-xPr_xFe_2 is a single phase (Dy, Pr)Fe_2 with MgCu_2-type structure and the second phase is (Dy, Pr)Fe_3 when x≤0.2. The amount of (Dy, Pr)Fe_3 phase increases with increasing Pr content and becomes the main phase when x=0.4. The matrix of Dy1_-x.Pr_xFe_2 is found to be the (Dy, Pr)_2Fe_17 phase with Th_2Zn_17-type structure when x=0.5. It is found that the amount of the cubic Laves phase (Dy, Pr)(Fe, Co)_2 in the Dy_0.6Pr_0.4(Fe_l-Co_y)2 increases with increasing Co concentration when 0≤y≤0.6. The substitution of Ni for Fe is nearly not favorable for the formation of the cubic Laves phase (Dy, Pr)(Fe, Ni)_2 in (Dy_1-xPr_x)Fe_2. The matrix of (Tb_1-z Pr_z)(Fe_0.4Co_0.6)_2 is a (Tb, Pr)(Fe, Co)_2 phase with the MgC_u2-type cubic Laves structure and a second phase of small amount is (Tb. Pr)(Fe, Co)_3 phase when z≤O.2, z=0.5 and 1.0. When 0.2<z≤0.4, the amount of the (Tb, Pr)(Fe, Co)_3 phase with PuNi_3-type structure increases with increasing z and becomes the main phase when z=0.4. When 0.5<z≤0.6 the amount of the (Tb, Pr)(Fe, Co)_3 phase increases sharply, whereas for 0.6<z≤0.8 it decreases with increasing z. The polycrystalline magnetostriction, λ|| - λ|. at room temperature of Dy_l-xPr_xFe_2 exhibits a peak when x=0.3. The λ|| - λ| for Dy_0.6Pr_0.4(Fe_1-y.M_y)_2 (M=Co, Ni) and Tb_l-zPrz(Fe_0.4Co_0.6)_2 is also examined.展开更多
The Gauss-Markov (GM) model and the Errors-in-Variables (EIV) model are frequently used to perform 3D coordinate transformations in geodesy and engineering surveys. In these applications, because the observation e...The Gauss-Markov (GM) model and the Errors-in-Variables (EIV) model are frequently used to perform 3D coordinate transformations in geodesy and engineering surveys. In these applications, because the observation errors in original coordinates system are also taken into account, the latter is more accurate and reasonable than the former. Although the Weighted Total Least Squares (WTLS) technique has been intro- duced into coordinate transformations as the measured points are heteroscedastic and correlated, the Variance- Covariance Matrix (VCM) of observations is restricted by a particular structure, namely, only the correlations of each points are taken into account. Because the 3D datum transformation with large rotation angle is a non- linear problem, the WTLS is no longer suitable in this ease. In this contribution, we suggested the nonlinear WTLS adjustments with equality constraints (NWTLS-EC) for 3D datum transformation with large rotation an- gle, which removed the particular structure restriction on the VCM. The Least Squares adjustment with Equality (LSE) constraints is employed to solve NWTLS-EC as the nonlinear model has been linearized, and an iterative algorithm is proposed with the LSE solution. A simulation study of 3D datum transformation with large rotation angle is given to insight into the feasibility of our algorithm at last.展开更多
When linearizing three-dimensional(3 D)coordinate similarity transformation model with large rotations,we usually encounter the ill-posed normal matrix which may aggravate the instability of solutions.To alleviate the...When linearizing three-dimensional(3 D)coordinate similarity transformation model with large rotations,we usually encounter the ill-posed normal matrix which may aggravate the instability of solutions.To alleviate the problem,a series of conversions are contributed to the 3 D coordinate similarity transformation model in this paper.We deduced a complete solution for the 3 D coordinate similarity transformation at any rotation with the nonlinear adjustment methodology,which involves the errors of the common and the non-common points.Furthermore,as the large condition number of the normal matrix resulted in an intractable form,we introduced the bary-centralization technique and a surrogate process for deterministic element of the normal matrix,and proved its benefit for alleviating the condition number.The experimental results show that our approach can obtain the smaller condition number to stabilize the convergence of the interested parameters.Especially,our approach can be implemented for considering the errors of the common and the non-common points,thus the accuracy of the transformed coordinates improves.展开更多
The R-phase transformation process in selected TiNi alloys has been studied in great detail by using in situ TEM technique. The R-phase transformation was found to be a reversible thermoelastic displacive transformati...The R-phase transformation process in selected TiNi alloys has been studied in great detail by using in situ TEM technique. The R-phase transformation was found to be a reversible thermoelastic displacive transformation with a nucleation and growth process. The R-phase nucleates at the precipitate/matrix interface in aged specimens and grows by moving the coherent R/matrix interfaces. The stress field of Ti3Ni4 precipitates plays a much more important role in the formation of the R-phase than dislocations in aged TiNi alloy. The microstructure of the R-phase has also been studied.展开更多
Herein,a three-dimensional(3D)inversion method in the frequency domain based on a time–frequency transformation was developed to improve the efficiency of the 3D inversion of transient electromagnetic(TEM)data.The Fo...Herein,a three-dimensional(3D)inversion method in the frequency domain based on a time–frequency transformation was developed to improve the efficiency of the 3D inversion of transient electromagnetic(TEM)data.The Fourier transform related to the electromagnetic response in the frequency and time domains becomes a sine or cosine transform under the excitation of downward-step current.We established a transformation matrix based on the digital fi ltering calculation for the sine transform,and then the frequency domain projection of the TEM data was determined from the linear transformation system using the smoothing constrained least squares inversion method,in which only the imaginary part was used to maintain the TEM data transformation equivalence in the bidirectional projection.Thus,the time-domain TEM inversion problem was indirectly and effectively solved in the frequency domain.In the 3D inversion of the transformed frequency-domain data,the limited-memory Broyden–Fletcher–Goldfarb–Shannoquasi–Newton(L-BFGS)method was used and modifi ed with a restart strategy to adjust the regularization parameter when the algorithm tended to a local minimum.Synthetic data tests showed that our domain transformation method can stably project the TEM data into the frequency domain with very high accuracy;furthe rmore,the 3D inversion of the transformed frequency-domain data is stable,can be used to recover the real resistivity model with an acceptable effi ciency.展开更多
Transgenic lines were achieved by transforming the E. coli 1-phosphate mannitol dehydrogenase gene (mtl-D) into the Populus tomentosa Cart. genome. An Agrobacterium tumefaciens strain (AGL1), constructed by clonin...Transgenic lines were achieved by transforming the E. coli 1-phosphate mannitol dehydrogenase gene (mtl-D) into the Populus tomentosa Cart. genome. An Agrobacterium tumefaciens strain (AGL1), constructed by cloning mtl-D into the disarmed plasmid pBin438, was used to infect leaves of the clone YW2. The infected leaf discs were cultured on a medium containing 30 mg.L 1 kanamycin and 500 mg.L 1 cefotaxime. Transgenic plantlets regenerated from the infected leaves, rooted on the medium con- taining 30 mg.L 1 kanamycin. PCR and a Southern blotting test verified that the exogenous mtl-D gene had integrated into the trans- formation plants of the P. tomentosa genome. The mannitol content in control plant was 69 gg.gl FW, and the mannitol contents of the transgenic lines T1 to T5 ranged between 103.7 and 289.5 μg·g^-1 FW. Of the shoots of the control plants 20% survived; on the medium containing 0.6% NaCl, 60% and 70% of two transgenic shoots survived on a medium containing 0.8% NaCI.展开更多
In the design of 3-D spherically symmetric FIR filters via the McClellan transformation, two methods are proposed to determine the transformation parameters. The first is to improve the original 3-D algorithm by explo...In the design of 3-D spherically symmetric FIR filters via the McClellan transformation, two methods are proposed to determine the transformation parameters. The first is to improve the original 3-D algorithm by exploiting the 2-D effective methods in 3-D. This method can change the constrained optimization algorithm into the unconstrained one and makes the design easier to realize. The second method is to solve the coupled equations under constrained conditions and a set of ideal parameters can be gotten. The design example shows that the two methods are all efficient and easier than the original algorithm.展开更多
In this paper, a transformation model named SARC(static-filter adjustment with restricted condition) is presented, which is more practical and more rigorous in theory and fitting any angle of rotation parameter. The t...In this paper, a transformation model named SARC(static-filter adjustment with restricted condition) is presented, which is more practical and more rigorous in theory and fitting any angle of rotation parameter. The transformation procedure is divided into 4 steps: ① the original and object coordinates can be regarded as observations with errors; ② rigorous formula is firstly deduced in order to compute the first approximation of the transformation parameters by use of four common points and the transformation equation is linearized; ③ calculate the most probable values and variances of the seven transformation parameters by SARC model; ④ to demonstrate validity of SARC , an example is given.展开更多
In China, the real industrialization and modernization process started in 1949, when the Chinese people were emancipated from the yoke of the Kuomintang and the People's Republic of China (P.R.C) was founded. Howe...In China, the real industrialization and modernization process started in 1949, when the Chinese people were emancipated from the yoke of the Kuomintang and the People's Republic of China (P.R.C) was founded. However, the road of emancipation has been a bumpy one. In particular, the emancipation of the mind has often been full of twists and turns. The tremendous liberation of social productive forces originated in the emancipation of the mind, whose truth has been tested by economic development practices. In the past 60 years China has paid tremendous efforts and costs in pursuit of emancipation, and today it still needs to emancipate the mind anew. For 60 years, since the formation of P.R. C, the country has kept pursuing the emancipation of the mind while exploring ways of change in institution, strategy and policy. In the first 30 years China attempted to devise an idealistic approach of transition to the socialist planned economic system, which was characterized by continuous revolution and movement. In the second 30 years China explored a realistic approach of transition to the socialist market economic system, which is characterized by incremental reform and opening-up. For six decades industry has remained at the forefront of transformation. The emancipation of the mind and the realization of change aim to ultimately make China a strong nation with an affluent people. The purpose of the six-decade struggle in new China is to erase the stigma of "being poor and blank," secure a firm and strong foothold in the world, restore China's status as a world power and let the Chinese people enjoy the affluence and welfare of a well-off society. The central mission of this national revitalization is to realize industrialization. Therefore, industrialization has been the central theme of China's revitalization in the past 60 years. After 60 years of industrialization, hundreds of millions of Chinese people are now able to enjoy ever-increasing wealth from industrial civilization. However, still a larger proportion of China's 1.3 billion people are awaiting industrial civilization. In this sense, industrialization is not only the focus of China's socioeconomic development but also the world's largest livelihood mission. Industrial development is more of a means of enhancing people's livelihood than a means of regaining the title as a world power. This will become one of the distinctive characteristics of China's industrialization in the new stage.展开更多
The method of preparing D-phenylalanine by asymmetric transformation is reported. D-phenylalanine was prepared from DL-phenylalanine by two-step reaction. D-phenylalanine (2S, 3S)-tartrate was prepared by heating DL-p...The method of preparing D-phenylalanine by asymmetric transformation is reported. D-phenylalanine was prepared from DL-phenylalanine by two-step reaction. D-phenylalanine (2S, 3S)-tartrate was prepared by heating DL-phenylalanine, salicylaldehyde, and (2S, 3S)-tartaric acid in propionic acid; the obtained D-phenylalanine (2S, 3S)-tartrate was treated with triethylamine in ethanol giving D-phenylalanine with 98% optical purity in 69% yield.展开更多
This paper presents an algorithm for coding video signal based on 3-D wavelet transformation. When the frame order t of a video signal is replaced by order 2, the video signal can be looked as a block in 3-D space. Af...This paper presents an algorithm for coding video signal based on 3-D wavelet transformation. When the frame order t of a video signal is replaced by order 2, the video signal can be looked as a block in 3-D space. After splitting the block into smaller sub-blocks, imitate the method of 2-D wavelet transformation for images, we can transform the sub-blocks with 3-D wavelet. Most of video signal energy is in the decomposed low-frequency sub-bands. These sub-bands affect the visual quality of the video signal most. Quantizing different sub-bands with different precision and then entropy encoding each sub-band, we can eliminate inter- and intra-frame redundancy of the video signal and compress data. Our simulation experiments show that this algorithm can achieve very good result.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant No.62075241).
文摘Single-pixel imaging(SPI)can transform 2D or 3D image data into 1D light signals,which offers promising prospects for image compression and transmission.However,during data communication these light signals in public channels will easily draw the attention of eavesdroppers.Here,we introduce an efficient encryption method for SPI data transmission that uses the 3D Arnold transformation to directly disrupt 1D single-pixel light signals and utilizes the elliptic curve encryption algorithm for key transmission.This encryption scheme immediately employs Hadamard patterns to illuminate the scene and then utilizes the 3D Arnold transformation to permutate the 1D light signal of single-pixel detection.Then the transformation parameters serve as the secret key,while the security of key exchange is guaranteed by an elliptic curve-based key exchange mechanism.Compared with existing encryption schemes,both computer simulations and optical experiments have been conducted to demonstrate that the proposed technique not only enhances the security of encryption but also eliminates the need for complicated pattern scrambling rules.Additionally,this approach solves the problem of secure key transmission,thus ensuring the security of information and the quality of the decrypted images.
文摘The transformation behavior of Ni Ti Nb based alloys was analysed.The absence of R phase transformation in these alloys is related to the stress field in the NiTi matrix.The thermal mismatch stress was calculated by the Eshelby method in Ni Ti Nb alloys.The results show that the mean matrix elastic stress field is isostatic tensile,there is no preferred stress in [111] B 2 direction.The mean matrix stress from the thermal misfit between NiTi matrix and β Nb particle is too small to induce dislocations.All the factors tend to inhibit R phase transformation.
基金supported in part by the Major Project for New Generation of AI (2018AAA0100400)the National Natural Science Foundation of China (61836014,U21B2042,62072457,62006231)the InnoHK Program。
文摘Monocular 3D object detection is challenging due to the lack of accurate depth information.Some methods estimate the pixel-wise depth maps from off-the-shelf depth estimators and then use them as an additional input to augment the RGB images.Depth-based methods attempt to convert estimated depth maps to pseudo-LiDAR and then use LiDAR-based object detectors or focus on the perspective of image and depth fusion learning.However,they demonstrate limited performance and efficiency as a result of depth inaccuracy and complex fusion mode with convolutions.Different from these approaches,our proposed depth-guided vision transformer with a normalizing flows(NF-DVT)network uses normalizing flows to build priors in depth maps to achieve more accurate depth information.Then we develop a novel Swin-Transformer-based backbone with a fusion module to process RGB image patches and depth map patches with two separate branches and fuse them using cross-attention to exchange information with each other.Furthermore,with the help of pixel-wise relative depth values in depth maps,we develop new relative position embeddings in the cross-attention mechanism to capture more accurate sequence ordering of input tokens.Our method is the first Swin-Transformer-based backbone architecture for monocular 3D object detection.The experimental results on the KITTI and the challenging Waymo Open datasets show the effectiveness of our proposed method and superior performance over previous counterparts.
文摘Three transformation models (Bursa-Wolf, Molodensky, and WTUSM) are generally used between two data systems transformation. The linear models are used when the rotation angles are small; however, when the rotation angles get bigger, model errors will be produced. In this paper, we present a method with three main terms:① the traditional rotation angles θ,φ,ψ are substituted with a,b,c which are three respective values in the anti-symmetrical or Lodrigues matrix; ② directly and accurately calculating the formula of seven parameters in any value of rotation angles; and ③ a corresponding adjustment model is established. This method does not use the triangle function. Instead it uses addition, subtraction, multiplication and division, and the complexity of the equation is reduced, making the calculation easy and quick.
文摘Some problems connect ed with production of new light-weight filler type are considered for sandwich layers. Constructively, the filler is the folded structure that can be developed on a plane. This feature makes it possible to produce the filler by isometric t ransformation of thin sheet through local bending without material stretching.Th e main difficulty is that the bending must be carried out along all lines of com plex-shaped marking-out at a time. The problem of shaping can be solved by use of the original shaping device that can be transformed in operation. The herein -presented technology of production makes it possible to fabricate parts with d eep relief using a wide gamut of different materials even as the thin-sheet met al alloys and paper.
文摘Measurements of electrical resistivity, X-ray diffraction, and tensile test at room temperature and ?196°C were performed to investigate the effects of Al addition substituting Ni on the phase transformation behaviors, the mechanical properties, and the shape memory effects of Ti50Ni47Fe2Al1 and Ti50Ni46.5Fe2.5Al1 alloys. It is found that 1at% Al addition dramatically decreases the martensitic start transformation temperature and expands the transformation temperature range of R-phase for TiNiFeAl alloys. The results of tensile test indicate that 1at% Al improves the yield strength of Ti50Ni47Fe2Al1 and Ti50Ni46.5Fe2.5Al1 alloys by 40% and 64%, but de- creases the plasticity to 11% and 12% from 26% and 27% respectively. Moreover, excellent shape memory effect of 6.6% and 7.5% were found in Ti50Ni47Fe2Al1 and Ti50Ni46.5Fe2.5Al1 alloys, which results from the stress-induced martensite transformation from the R-phase.
基金National Natural Sciences FOundation of China!59725103National Natural Sciences FOundation of China!59871054Science and
文摘Structure and magnetostriction of Dy1-Pr_x Fe_2 (0≤x≤0.5), Dy_0.6Pr_0.4(Fe_1-_yT_y)_2 (0≤y≤0.6), and Tb_1-z Pr_z(Fe_0.4Co_0.6)_2 (0≤z≤1.0) alloys (T=Co, Ni) have been investigated. It is found that the matrix of the alloys Dy_1-xPr_xFe_2 is a single phase (Dy, Pr)Fe_2 with MgCu_2-type structure and the second phase is (Dy, Pr)Fe_3 when x≤0.2. The amount of (Dy, Pr)Fe_3 phase increases with increasing Pr content and becomes the main phase when x=0.4. The matrix of Dy1_-x.Pr_xFe_2 is found to be the (Dy, Pr)_2Fe_17 phase with Th_2Zn_17-type structure when x=0.5. It is found that the amount of the cubic Laves phase (Dy, Pr)(Fe, Co)_2 in the Dy_0.6Pr_0.4(Fe_l-Co_y)2 increases with increasing Co concentration when 0≤y≤0.6. The substitution of Ni for Fe is nearly not favorable for the formation of the cubic Laves phase (Dy, Pr)(Fe, Ni)_2 in (Dy_1-xPr_x)Fe_2. The matrix of (Tb_1-z Pr_z)(Fe_0.4Co_0.6)_2 is a (Tb, Pr)(Fe, Co)_2 phase with the MgC_u2-type cubic Laves structure and a second phase of small amount is (Tb. Pr)(Fe, Co)_3 phase when z≤O.2, z=0.5 and 1.0. When 0.2<z≤0.4, the amount of the (Tb, Pr)(Fe, Co)_3 phase with PuNi_3-type structure increases with increasing z and becomes the main phase when z=0.4. When 0.5<z≤0.6 the amount of the (Tb, Pr)(Fe, Co)_3 phase increases sharply, whereas for 0.6<z≤0.8 it decreases with increasing z. The polycrystalline magnetostriction, λ|| - λ|. at room temperature of Dy_l-xPr_xFe_2 exhibits a peak when x=0.3. The λ|| - λ| for Dy_0.6Pr_0.4(Fe_1-y.M_y)_2 (M=Co, Ni) and Tb_l-zPrz(Fe_0.4Co_0.6)_2 is also examined.
基金supported by the National Natural Science Foundation of China(41074017)
文摘The Gauss-Markov (GM) model and the Errors-in-Variables (EIV) model are frequently used to perform 3D coordinate transformations in geodesy and engineering surveys. In these applications, because the observation errors in original coordinates system are also taken into account, the latter is more accurate and reasonable than the former. Although the Weighted Total Least Squares (WTLS) technique has been intro- duced into coordinate transformations as the measured points are heteroscedastic and correlated, the Variance- Covariance Matrix (VCM) of observations is restricted by a particular structure, namely, only the correlations of each points are taken into account. Because the 3D datum transformation with large rotation angle is a non- linear problem, the WTLS is no longer suitable in this ease. In this contribution, we suggested the nonlinear WTLS adjustments with equality constraints (NWTLS-EC) for 3D datum transformation with large rotation an- gle, which removed the particular structure restriction on the VCM. The Least Squares adjustment with Equality (LSE) constraints is employed to solve NWTLS-EC as the nonlinear model has been linearized, and an iterative algorithm is proposed with the LSE solution. A simulation study of 3D datum transformation with large rotation angle is given to insight into the feasibility of our algorithm at last.
基金supported by the National Natural Science Foundation of China,Nos.41874001 and 41664001Support Program for Outstanding Youth Talents in Jiangxi Province,No.20162BCB23050National Key Research and Development Program,No.2016YFB0501405。
文摘When linearizing three-dimensional(3 D)coordinate similarity transformation model with large rotations,we usually encounter the ill-posed normal matrix which may aggravate the instability of solutions.To alleviate the problem,a series of conversions are contributed to the 3 D coordinate similarity transformation model in this paper.We deduced a complete solution for the 3 D coordinate similarity transformation at any rotation with the nonlinear adjustment methodology,which involves the errors of the common and the non-common points.Furthermore,as the large condition number of the normal matrix resulted in an intractable form,we introduced the bary-centralization technique and a surrogate process for deterministic element of the normal matrix,and proved its benefit for alleviating the condition number.The experimental results show that our approach can obtain the smaller condition number to stabilize the convergence of the interested parameters.Especially,our approach can be implemented for considering the errors of the common and the non-common points,thus the accuracy of the transformed coordinates improves.
文摘The R-phase transformation process in selected TiNi alloys has been studied in great detail by using in situ TEM technique. The R-phase transformation was found to be a reversible thermoelastic displacive transformation with a nucleation and growth process. The R-phase nucleates at the precipitate/matrix interface in aged specimens and grows by moving the coherent R/matrix interfaces. The stress field of Ti3Ni4 precipitates plays a much more important role in the formation of the R-phase than dislocations in aged TiNi alloy. The microstructure of the R-phase has also been studied.
基金the National Key Research and Development Program of China(No.2016YFC060110403).
文摘Herein,a three-dimensional(3D)inversion method in the frequency domain based on a time–frequency transformation was developed to improve the efficiency of the 3D inversion of transient electromagnetic(TEM)data.The Fourier transform related to the electromagnetic response in the frequency and time domains becomes a sine or cosine transform under the excitation of downward-step current.We established a transformation matrix based on the digital fi ltering calculation for the sine transform,and then the frequency domain projection of the TEM data was determined from the linear transformation system using the smoothing constrained least squares inversion method,in which only the imaginary part was used to maintain the TEM data transformation equivalence in the bidirectional projection.Thus,the time-domain TEM inversion problem was indirectly and effectively solved in the frequency domain.In the 3D inversion of the transformed frequency-domain data,the limited-memory Broyden–Fletcher–Goldfarb–Shannoquasi–Newton(L-BFGS)method was used and modifi ed with a restart strategy to adjust the regularization parameter when the algorithm tended to a local minimum.Synthetic data tests showed that our domain transformation method can stably project the TEM data into the frequency domain with very high accuracy;furthe rmore,the 3D inversion of the transformed frequency-domain data is stable,can be used to recover the real resistivity model with an acceptable effi ciency.
文摘Transgenic lines were achieved by transforming the E. coli 1-phosphate mannitol dehydrogenase gene (mtl-D) into the Populus tomentosa Cart. genome. An Agrobacterium tumefaciens strain (AGL1), constructed by cloning mtl-D into the disarmed plasmid pBin438, was used to infect leaves of the clone YW2. The infected leaf discs were cultured on a medium containing 30 mg.L 1 kanamycin and 500 mg.L 1 cefotaxime. Transgenic plantlets regenerated from the infected leaves, rooted on the medium con- taining 30 mg.L 1 kanamycin. PCR and a Southern blotting test verified that the exogenous mtl-D gene had integrated into the trans- formation plants of the P. tomentosa genome. The mannitol content in control plant was 69 gg.gl FW, and the mannitol contents of the transgenic lines T1 to T5 ranged between 103.7 and 289.5 μg·g^-1 FW. Of the shoots of the control plants 20% survived; on the medium containing 0.6% NaCl, 60% and 70% of two transgenic shoots survived on a medium containing 0.8% NaCI.
文摘In the design of 3-D spherically symmetric FIR filters via the McClellan transformation, two methods are proposed to determine the transformation parameters. The first is to improve the original 3-D algorithm by exploiting the 2-D effective methods in 3-D. This method can change the constrained optimization algorithm into the unconstrained one and makes the design easier to realize. The second method is to solve the coupled equations under constrained conditions and a set of ideal parameters can be gotten. The design example shows that the two methods are all efficient and easier than the original algorithm.
文摘In this paper, a transformation model named SARC(static-filter adjustment with restricted condition) is presented, which is more practical and more rigorous in theory and fitting any angle of rotation parameter. The transformation procedure is divided into 4 steps: ① the original and object coordinates can be regarded as observations with errors; ② rigorous formula is firstly deduced in order to compute the first approximation of the transformation parameters by use of four common points and the transformation equation is linearized; ③ calculate the most probable values and variances of the seven transformation parameters by SARC model; ④ to demonstrate validity of SARC , an example is given.
文摘In China, the real industrialization and modernization process started in 1949, when the Chinese people were emancipated from the yoke of the Kuomintang and the People's Republic of China (P.R.C) was founded. However, the road of emancipation has been a bumpy one. In particular, the emancipation of the mind has often been full of twists and turns. The tremendous liberation of social productive forces originated in the emancipation of the mind, whose truth has been tested by economic development practices. In the past 60 years China has paid tremendous efforts and costs in pursuit of emancipation, and today it still needs to emancipate the mind anew. For 60 years, since the formation of P.R. C, the country has kept pursuing the emancipation of the mind while exploring ways of change in institution, strategy and policy. In the first 30 years China attempted to devise an idealistic approach of transition to the socialist planned economic system, which was characterized by continuous revolution and movement. In the second 30 years China explored a realistic approach of transition to the socialist market economic system, which is characterized by incremental reform and opening-up. For six decades industry has remained at the forefront of transformation. The emancipation of the mind and the realization of change aim to ultimately make China a strong nation with an affluent people. The purpose of the six-decade struggle in new China is to erase the stigma of "being poor and blank," secure a firm and strong foothold in the world, restore China's status as a world power and let the Chinese people enjoy the affluence and welfare of a well-off society. The central mission of this national revitalization is to realize industrialization. Therefore, industrialization has been the central theme of China's revitalization in the past 60 years. After 60 years of industrialization, hundreds of millions of Chinese people are now able to enjoy ever-increasing wealth from industrial civilization. However, still a larger proportion of China's 1.3 billion people are awaiting industrial civilization. In this sense, industrialization is not only the focus of China's socioeconomic development but also the world's largest livelihood mission. Industrial development is more of a means of enhancing people's livelihood than a means of regaining the title as a world power. This will become one of the distinctive characteristics of China's industrialization in the new stage.
文摘The method of preparing D-phenylalanine by asymmetric transformation is reported. D-phenylalanine was prepared from DL-phenylalanine by two-step reaction. D-phenylalanine (2S, 3S)-tartrate was prepared by heating DL-phenylalanine, salicylaldehyde, and (2S, 3S)-tartaric acid in propionic acid; the obtained D-phenylalanine (2S, 3S)-tartrate was treated with triethylamine in ethanol giving D-phenylalanine with 98% optical purity in 69% yield.
文摘This paper presents an algorithm for coding video signal based on 3-D wavelet transformation. When the frame order t of a video signal is replaced by order 2, the video signal can be looked as a block in 3-D space. After splitting the block into smaller sub-blocks, imitate the method of 2-D wavelet transformation for images, we can transform the sub-blocks with 3-D wavelet. Most of video signal energy is in the decomposed low-frequency sub-bands. These sub-bands affect the visual quality of the video signal most. Quantizing different sub-bands with different precision and then entropy encoding each sub-band, we can eliminate inter- and intra-frame redundancy of the video signal and compress data. Our simulation experiments show that this algorithm can achieve very good result.