Scalar-tensor theories of gravity are considered to be competitors to Einstein's theory of general relativity for the description of classical gravity,as they are used to build feasible models for cosmic inflation...Scalar-tensor theories of gravity are considered to be competitors to Einstein's theory of general relativity for the description of classical gravity,as they are used to build feasible models for cosmic inflation.These theories can be formulated both in the Jordan and Einstein frame,which are related by a Weyl transformation with a field transformation,known together as a frame transformation.These theories formulated in the above two frames are often considered to be equivalent from the point of view of classical theory.However,this is no longer true from the quantum field theoretical perspective.In the present article,we show that the Ward identities derived in the above two frames are not connected through the frame transformation.This shows that the quantum field theories formulated in these two frames are not equivalent to each other.Moreover,this inequivalence is also shown by comparing the effective actions derived in these two frames.展开更多
A muitisensor image fusion algorithm is described using 2-dimensional nonseparable wavelet frame （NWF） transform. The source muitisensor images are first decomposed by the NWF transform. Then, the NWF transform coef...A muitisensor image fusion algorithm is described using 2-dimensional nonseparable wavelet frame （NWF） transform. The source muitisensor images are first decomposed by the NWF transform. Then, the NWF transform coefficients of the source images are combined into the composite NWF transform coefficients. Inverse NWF transform is performed on the composite NWF transform coefficients in order to obtain the intermediate fused image. Finally, intensity adjustment is applied to the intermediate fused image in order to maintain the dynamic intensity range. Experiment resuits using real data show that the proposed algorithm works well in muitisensor image fusion.展开更多
为进一步提升跟踪算法在历史帧信息利用和目标特征表达方面的性能,提出基于特征增强和历史帧选择的Transformer视觉跟踪算法(feature enhancement and history frame selection based Transformer visual tracking, FEHST).首先,在骨干...为进一步提升跟踪算法在历史帧信息利用和目标特征表达方面的性能,提出基于特征增强和历史帧选择的Transformer视觉跟踪算法(feature enhancement and history frame selection based Transformer visual tracking, FEHST).首先,在骨干网络中引入动态预测模块,通过稀疏化策略提高自注意力机制的计算效率,聚焦目标区域特征;其次,提出特征增强模块,将局部信息与全局信息的优势相结合,提升特征的表达能力;最后,采用自适应历史帧选择策略,提升跟踪器对目标动态信息的关注.在LaSOT、TrackingNet、GOT-10K和OTB100等数据集上进行了大量的实验,实验结果显示,在LaSOT、TrackingNet、OTB100上分别取得70.1%、83.0%和71.6%的成功率,在GOT-10K上取得71.4%的平均重叠度,并能以27 FPS的速度运行.展开更多
In this paper exact solution for a homogenous incompressible, second grade fluid in a rotating frame through porous media has been provided using hodograph-Legendre transformation method. Results are summarised in the...In this paper exact solution for a homogenous incompressible, second grade fluid in a rotating frame through porous media has been provided using hodograph-Legendre transformation method. Results are summarised in the form of theorems. Two examples have been taken and streamline patterns are shown for the solutions.展开更多
<div style="text-align:justify;"> Digital watermarking technology plays a powerful role in the effective protection of digital media copyright, image authentication, image sharing, image information tr...<div style="text-align:justify;"> Digital watermarking technology plays a powerful role in the effective protection of digital media copyright, image authentication, image sharing, image information transmission and other fields. Driven by strong demand, digital image watermarking technology has aroused widespread research interest and has gradually developed into one of the most active research directions in information science. In this paper, we present a novel robust digital watermarking algorithm based on discrete radon transform tight frame in finite-set (FDRT). FDRT of the zero mean image is a tight frame, the frame boundary <em><strong>A</strong></em> = <em><strong>B</strong></em> = 1, the dual of the frame is itself. The decomposition and reconstruction of the FDRT tight frame will not cause the phenomenon of image distortion. The embedding of hidden watermark is to add a weak signal to the strong background of the original image. Watermark extraction is to effectively identify the embedded weak signal. The feasibility of the watermarking algorithm is analyzed from two aspects of information hiding and robustness. We select the independent Gaussian random vector as the watermark series, and the peak signal-to-noise ratio (PSNR) as the visual degradation criterion of the watermark image. Basing the FDRT compact stand dual operator, we derived the relationship among the strength parameter, square sum of watermark series, the PSNR. Using Checkmark system, the simulation results show that the algorithm is robust enough to some very important image processing attacks such as lossy compression, MAP, filtering, segmentation, edge enhancement, jitter, quadratic modulation and general geometric attack (scaling, rotation, shearing), etc. </div>展开更多
为解决传统差分混沌移位键控(differential chaotic shift keying,DCSK)系统安全性较差及误码性能受限的问题,提出一种结合脉冲位置调制与动态帧变换技术的DCSK(frame-transform DCSK system based on pulse position modulation,FT-PPM...为解决传统差分混沌移位键控(differential chaotic shift keying,DCSK)系统安全性较差及误码性能受限的问题,提出一种结合脉冲位置调制与动态帧变换技术的DCSK(frame-transform DCSK system based on pulse position modulation,FT-PPM-DCSK)系统,实现安全性与误码性能的协同优化。通过推导系统在加性高斯白噪声(additive white Gaussian noise,AWGN)信道下的误比特率(BER)表达式,基于蒙特卡洛仿真验证其性能。实验结果表明,与基准DCSK系统相比,FT-PPM-DCSK系统提高了误码性能且具有更高的安全性。展开更多
正交频分复用(Orthogonal Frequency Division Multiplexing,OFDM)调制因其高效的频带利用率和良好的抗多径能力广泛用于合作与非合作通信系统中。合作通信场景下,通常接收机可以利用已知帧结构实现OFDM信号的检测。但在非合作场景下,...正交频分复用(Orthogonal Frequency Division Multiplexing,OFDM)调制因其高效的频带利用率和良好的抗多径能力广泛用于合作与非合作通信系统中。合作通信场景下,通常接收机可以利用已知帧结构实现OFDM信号的检测。但在非合作场景下,接收机没有足够的先验信息,导致帧检测难度加大。针对这一问题,提出了一种适合于非合作通信场景的OFDM数据帧的检测算法。所提算法利用快速小波变换将含噪OFDM信号的功率包络进行小波分解与重构,对重构得到的功率包络进行差分运算后,再通过与阈值比较实现OFDM信号的帧检测。相较于混合能量检测算法,所提算法计算预设参数少,复杂度低。仿真结果表明,所提算法在加性高斯白噪声信道和多径衰落信道下带内信噪比分别取-6 dB和3 dB时即可实现零漏报率,且零漏报率的阈值选取范围比混合能量检测算法扩大了约6 dB。展开更多
The workpiece frames relative to each robot base frame should be known in advance for the proper operation of twin-robot nondestructive testing system. However, when two robots are separated from the workpieces, the t...The workpiece frames relative to each robot base frame should be known in advance for the proper operation of twin-robot nondestructive testing system. However, when two robots are separated from the workpieces, the twin robots cannot reach the same point to complete the process of workpiece frame positioning. Thus, a new method is proposed to solve the problem of coincidence between workpiece frames. Transformation between two robot base frames is initiated by measuring the coordinate values of three non-collinear calibration points. The relationship between the workpiece frame and that of the slave robot base frame is then determined according to the known transformation of two robot base frames, as well as the relationship between the workpiece frame and that of the master robot base frame. Only one robot is required to actually measure the coordinate values of the calibration points on the workpiece. This requirement is beneficial when one of the robots cannot reach and measure the calibration points. The coordinate values of the calibration points are derived by driving the robot hand to the points and recording the values of top center point（TCP） coordinates. The translation and rotation matrices relate either the two robot base frames or the workpiece and master robot. The coordinated are solved using the measured values of the calibration points according to the Cartesian transformation principle. An optimal method is developed based on exponential mapping of Lie algebra to ensure that the rotation matrix is orthogonal. Experimental results show that this method involves fewer steps, offers significant advantages in terms of operation and time-saving. A method used to synchronize workpiece frames in twin-robot system automatically is presented.展开更多
文摘Scalar-tensor theories of gravity are considered to be competitors to Einstein's theory of general relativity for the description of classical gravity,as they are used to build feasible models for cosmic inflation.These theories can be formulated both in the Jordan and Einstein frame,which are related by a Weyl transformation with a field transformation,known together as a frame transformation.These theories formulated in the above two frames are often considered to be equivalent from the point of view of classical theory.However,this is no longer true from the quantum field theoretical perspective.In the present article,we show that the Ward identities derived in the above two frames are not connected through the frame transformation.This shows that the quantum field theories formulated in these two frames are not equivalent to each other.Moreover,this inequivalence is also shown by comparing the effective actions derived in these two frames.
文摘A muitisensor image fusion algorithm is described using 2-dimensional nonseparable wavelet frame （NWF） transform. The source muitisensor images are first decomposed by the NWF transform. Then, the NWF transform coefficients of the source images are combined into the composite NWF transform coefficients. Inverse NWF transform is performed on the composite NWF transform coefficients in order to obtain the intermediate fused image. Finally, intensity adjustment is applied to the intermediate fused image in order to maintain the dynamic intensity range. Experiment resuits using real data show that the proposed algorithm works well in muitisensor image fusion.
文摘为进一步提升跟踪算法在历史帧信息利用和目标特征表达方面的性能,提出基于特征增强和历史帧选择的Transformer视觉跟踪算法(feature enhancement and history frame selection based Transformer visual tracking, FEHST).首先,在骨干网络中引入动态预测模块,通过稀疏化策略提高自注意力机制的计算效率,聚焦目标区域特征;其次,提出特征增强模块,将局部信息与全局信息的优势相结合,提升特征的表达能力;最后,采用自适应历史帧选择策略,提升跟踪器对目标动态信息的关注.在LaSOT、TrackingNet、GOT-10K和OTB100等数据集上进行了大量的实验,实验结果显示,在LaSOT、TrackingNet、OTB100上分别取得70.1%、83.0%和71.6%的成功率,在GOT-10K上取得71.4%的平均重叠度,并能以27 FPS的速度运行.
文摘In this paper exact solution for a homogenous incompressible, second grade fluid in a rotating frame through porous media has been provided using hodograph-Legendre transformation method. Results are summarised in the form of theorems. Two examples have been taken and streamline patterns are shown for the solutions.
文摘<div style="text-align:justify;"> Digital watermarking technology plays a powerful role in the effective protection of digital media copyright, image authentication, image sharing, image information transmission and other fields. Driven by strong demand, digital image watermarking technology has aroused widespread research interest and has gradually developed into one of the most active research directions in information science. In this paper, we present a novel robust digital watermarking algorithm based on discrete radon transform tight frame in finite-set (FDRT). FDRT of the zero mean image is a tight frame, the frame boundary <em><strong>A</strong></em> = <em><strong>B</strong></em> = 1, the dual of the frame is itself. The decomposition and reconstruction of the FDRT tight frame will not cause the phenomenon of image distortion. The embedding of hidden watermark is to add a weak signal to the strong background of the original image. Watermark extraction is to effectively identify the embedded weak signal. The feasibility of the watermarking algorithm is analyzed from two aspects of information hiding and robustness. We select the independent Gaussian random vector as the watermark series, and the peak signal-to-noise ratio (PSNR) as the visual degradation criterion of the watermark image. Basing the FDRT compact stand dual operator, we derived the relationship among the strength parameter, square sum of watermark series, the PSNR. Using Checkmark system, the simulation results show that the algorithm is robust enough to some very important image processing attacks such as lossy compression, MAP, filtering, segmentation, edge enhancement, jitter, quadratic modulation and general geometric attack (scaling, rotation, shearing), etc. </div>
文摘为解决传统差分混沌移位键控(differential chaotic shift keying,DCSK)系统安全性较差及误码性能受限的问题,提出一种结合脉冲位置调制与动态帧变换技术的DCSK(frame-transform DCSK system based on pulse position modulation,FT-PPM-DCSK)系统,实现安全性与误码性能的协同优化。通过推导系统在加性高斯白噪声(additive white Gaussian noise,AWGN)信道下的误比特率(BER)表达式,基于蒙特卡洛仿真验证其性能。实验结果表明,与基准DCSK系统相比,FT-PPM-DCSK系统提高了误码性能且具有更高的安全性。
基金Supported by International S&T Cooperation Program of China(Grant No.2012DFA70260)High-end CNC Machine and Basic Manufacturing Equipment of Chinese Key National Science and Technology(Grant No.2011ZX04014-081)
文摘The workpiece frames relative to each robot base frame should be known in advance for the proper operation of twin-robot nondestructive testing system. However, when two robots are separated from the workpieces, the twin robots cannot reach the same point to complete the process of workpiece frame positioning. Thus, a new method is proposed to solve the problem of coincidence between workpiece frames. Transformation between two robot base frames is initiated by measuring the coordinate values of three non-collinear calibration points. The relationship between the workpiece frame and that of the slave robot base frame is then determined according to the known transformation of two robot base frames, as well as the relationship between the workpiece frame and that of the master robot base frame. Only one robot is required to actually measure the coordinate values of the calibration points on the workpiece. This requirement is beneficial when one of the robots cannot reach and measure the calibration points. The coordinate values of the calibration points are derived by driving the robot hand to the points and recording the values of top center point（TCP） coordinates. The translation and rotation matrices relate either the two robot base frames or the workpiece and master robot. The coordinated are solved using the measured values of the calibration points according to the Cartesian transformation principle. An optimal method is developed based on exponential mapping of Lie algebra to ensure that the rotation matrix is orthogonal. Experimental results show that this method involves fewer steps, offers significant advantages in terms of operation and time-saving. A method used to synchronize workpiece frames in twin-robot system automatically is presented.
