We-map is an interactive mobile map that can be easily communicated and applied on personal electronic devices,such as personal computers and mobile phones.Therefore,the study of direction systems and coordinate syste...We-map is an interactive mobile map that can be easily communicated and applied on personal electronic devices,such as personal computers and mobile phones.Therefore,the study of direction systems and coordinate systems is critical,and exploring reference frames is essential in direction and coordinate systems.Despite its significance,existing research on We-map lacks specific solutions for the exploration of reference frames is indispensable for the establishment of accurate direction and coordinate systems.In this paper,we endeavor to address this gap by elucidating the significance of We-map reference frames,defining them with mathematical constraints,summarizing their nature and characteristics,deriving their transformation relationships and representing them through mathematical formulars and equations.Our work contributes to the fundamental theory of We-map and provides valuable systems and support for the mathematical foundation of We-map,map production,and platform development.Ultimately,this research serves to advance the development of We-map.展开更多
China Geodetic Coordinate System 2000(CGCS2000)has been used for several years as a formal published reference frame.The coordinates of all global navigation satellite system(GNSS)stations in China need to be correcte...China Geodetic Coordinate System 2000(CGCS2000)has been used for several years as a formal published reference frame.The coordinates of all global navigation satellite system(GNSS)stations in China need to be corrected to align with the CGCS2000 frame.Different strategies can be adopted for the realization of an optimal reference frame.However,different strategies lead to different results,with differences as great as several decimeters when GNSS station coordinates are transformed into CGCS2000-defined coordinates.The two common methods for the coordinate correction of a GNSS station are quasi-stable adjustment under CGCS2000 and plate movement correction,and the differences between their results can be greater than 10 cm.In this study,a statistic method called"supervised clustering"is applied to the selection of GNSS reference stations;a new scheme named"partition spacing"for the grouping of all processed GNSS stations is proposed;and the plate movement correction method is used to correct the coordinates of all GNSS stations from the GNSS epoch to the CGCS2000 epoch.The results from the new partitioning method were found to be significantly better than those from the conventional station-blocking approach.When coordinates from the stations without grouping were used as the standard,the accuracy of all the three-dimensional coordinate components from the new partitioning method was better than 2 mm.The root mean squares(RMSs)of the velocities in the x,y,and z directions resulting from the supervised clustering method were 0.19,0.45,and 0.32 mm∙a1,respectively,which were much smaller than the values of 0.92,0.72,and 0.97 mm∙a1 that resulted from the conventional approach.In addition,singular spectrum analysis(SSA)was used to model and predict the position nonlinear movements.The modeling accuracies of SSA were better than 3,2,and 5 mm in the east(E),north(N),and up(U)directions,respectively;and its prediction accuracies were better than 5 mm and 1 cm for the horizontal and vertical domains,respectively.展开更多
The drag-free satellites are widely used in the field of fundamental science as they enable the high-precision measurement in pure gravity fields. This paper investigates the estimation of local orbital reference fram...The drag-free satellites are widely used in the field of fundamental science as they enable the high-precision measurement in pure gravity fields. This paper investigates the estimation of local orbital reference frame(LORF) for drag-free satellites. An approach, taking account of the combination of the minimum estimation error and power spectral density(PSD) constraint in frequency domain, is proposed. Firstly, the relationship between eigenvalues of estimator and transfer function is built to analyze the suppression and amplification effect on input signals and obtain the eigenvalue range. Secondly, an optimization model for state estimator design with minimum estimation error in time domain and PSD constraint in frequency domain is established. It is solved by the sequential quadratic programming(SQP) algorithm. Finally, the orbital reference frame estimation of low-earth-orbit satellite is taken as an example, and the estimator of minimum variance with PSD constraint is designed and analyzed using the method proposed in this paper.展开更多
This paper establishes the integral theory for the dynamics of nonlinear nonholonomic system in noninertial reference frame. Firstly, based on the Routh equation of the relative motion of nonlinear nonholonomic system...This paper establishes the integral theory for the dynamics of nonlinear nonholonomic system in noninertial reference frame. Firstly, based on the Routh equation of the relative motion of nonlinear nonholonomic system gives the first integral of the system. Secondly, by using cyclic integral or energy integral reduces the order of the equation and obtains generalized Routh equation and Whittaker equation respectively. Thirdly, derives canonical equation and variation equation and by using the first integral constructs integral invariant. And then, establishes the basic integral variants and the integral invariant of Poincare-Cartan type. Finally, we give a series of deductions.展开更多
We present a three-party reference frame independent quantum key distribution protocol which can be implemented without any alignment of reference frames between the sender and the receiver.The protocol exploits entan...We present a three-party reference frame independent quantum key distribution protocol which can be implemented without any alignment of reference frames between the sender and the receiver.The protocol exploits entangled states to establish a secret key among three communicating parties.We derive the asymptotic key rate for the proposed protocol against collective attacks and perform a finite-size key security analysis against general attacks in the presence of statistical fluctuations.We investigate the impact of reference frame misalignment on the stability of our protocol,and we obtain a transmission distance of 180 km,200 km,and 230 km for rotation of reference framesβ=π/6,β=π/8 andβ=0,respectively.Remarkably,our results demonstrate that our proposed protocol is not heavily affected by an increase in misalignment of reference frames as the achievable transmission distances are still comparable to the case where there is no misalignment in reference frames(whenβ=0).We also simulate the performance of our protocol for a fixed number of signals.Our results demonstrate that the protocol can achieve an effective key generation rate over a transmission distance of about 120 km with realistic 107 finite data signals and approximately achieve 195 km with 109 signals.Moreover,our proposed protocol is robust against noise in the quantum channel and achieves a threshold error rate of 22.7%.展开更多
This paper presents an option for modern dynamic terrestrial reference system realization in Uzbekistan for user needs. An additive model is explored to predict patterns of time series and investigate means of constru...This paper presents an option for modern dynamic terrestrial reference system realization in Uzbekistan for user needs. An additive model is explored to predict patterns of time series and investigate means of constructing forecast time series models in the future. The main components(trend, periodical, and irregular) of the KIUB(DORIS) and KIT3, TASH, MADK, and MTAL(GNSS) international stations coordinate time series were investigated. It was shown that seasonal nonlinear trends occurred both in the height(U) component of all stations and the east(E) component of high mountainous stations such as MTAL and MADK. The seasonal periodical portion of the time series determined from the additive model has a complicated pattern for all sites and can be explained as both hydrological signals in the region and improvement of observational quality. Amplitudes of the best-fitting sinusoids in the North component ranged between 1.73 and 8.76 mm; the East component ranged between 0.82 and 11.92 mm; and the Up component ranged between 3.11 and 40.81 mm. Regression analysis of the irregular portion of the height component of the two techniques at the Kitab station using tropospheric parameters(pressure and temperature) was confirmed as only 57% of the stochastic portion of the time series.展开更多
In this paper,a video compressed sensing reconstruction algorithm based on multidimensional reference frames is proposed using the sparse characteristics of video signals in different sparse representation domains.Fir...In this paper,a video compressed sensing reconstruction algorithm based on multidimensional reference frames is proposed using the sparse characteristics of video signals in different sparse representation domains.First,the overall structure of the proposed video compressed sensing algorithm is introduced in this paper.The paper adopts a multi-reference frame bidirectional prediction hypothesis optimization algorithm.Then,the paper proposes a reconstruction method for CS frames at the re-decoding end.In addition to using key frames of each GOP reconstructed in the time domain as reference frames for reconstructing CS frames,half-pixel reference frames and scaled reference frames in the pixel domain are also used as CS frames.Reference frames of CS frames are used to obtain higher quality assumptions.Themethod of obtaining reference frames in the pixel domain is also discussed in detail in this paper.Finally,the reconstruction algorithm proposed in this paper is compared with video compression algorithms in the literature that have better reconstruction results.Experiments show that the algorithm has better performance than the best multi-reference frame video compression sensing algorithm and can effectively improve the quality of slowmotion video reconstruction.展开更多
This paper presents the generalized principles of least action of variable mass nonholonomic nonconservative system in noninertial reference frame, proves the equivalence between Holder form and Suslov form, and then ...This paper presents the generalized principles of least action of variable mass nonholonomic nonconservative system in noninertial reference frame, proves the equivalence between Holder form and Suslov form, and then obtains differential equations of motion of variable mass nonholonomic nonconservative system in noninertial reference frame.展开更多
The new variational principle of Gauss's form of nonlinear nonholonomic nonpotential system relative to non-inertial reference frame is established by constructing generalized inertial potentials. Naether's th...The new variational principle of Gauss's form of nonlinear nonholonomic nonpotential system relative to non-inertial reference frame is established by constructing generalized inertial potentials. Naether's theorem and Naether's inverse theorem of the system above is presented and proved. Finally, one example is given to illustrate the application.展开更多
Paleogeography can be reconstructed using various crust-or mantle-based reference frames that make fundamentally different assumptions.The various reconstruction models differ significantly in continental paleolongitu...Paleogeography can be reconstructed using various crust-or mantle-based reference frames that make fundamentally different assumptions.The various reconstruction models differ significantly in continental paleolongitude,but it has been difficult to assess which models are more valid.We suggest here a "LLSVP test",where an assumed correlation between present-day large low velocity shear-wave provinces and the paleogeography of supercontinent Pangea at breakup ca.200 million years ago can be used to assess the relative accuracy of published reconstructions.Closest correlations between continental paleolongitude and the African LLSVP are achieved with mantle-based reference frames(moving hotspots and true polar wander),whereas shallower crustbased reference frames are shown to be invalid.The relative success of mantle-based frames,and thus the importance of the depth of reference frame,supports the notion that mantle convection is largely vertical compared to the horizontal plate motion of tectonics.展开更多
Houston,Texas,is one of the earliest regions to employ continuous GPS technology for land subsidence monitoring.Currently,there are over 200 permanent GPS stations located in the greater Houston area.The need for a co...Houston,Texas,is one of the earliest regions to employ continuous GPS technology for land subsidence monitoring.Currently,there are over 200 permanent GPS stations located in the greater Houston area.The need for a consistent and stable reference frame to precisely interpret local ground deformation has become critically important since the 1990s,because of the significant spreading of subsidence.We have established a stable Houston reference frame,designated Houston16,using publicly available GPS observations(>5 years)from 15 Continuously Operating Reference Stations(CORS)located outside of the greater Houston area.Applications of the reference frame in subsidence and faulting studies are demonstrated in this article.Houston16 is aligned in origin and scale with the International GNSS Reference Frame of 2008(IGS08).A 7-parameter method was employed to transform the GPS-derived positional time series from IGS08 to Houston16.The primary product of this study is the seven parameters for transforming Earth-Centered-Earth-Fixed XYZ coordinates from IGS08 to Houston16.The frame stability of Houston16 is approximately 1 mm/year.Houston16 will be updated every few years to mitigate degradation of the frame’s stability with time and to synchronize with future updates of the IGS reference frame.展开更多
We aim to study the thermodynamic properties of the spherically symmetric reference frames with uniform acceleration, including the spherically symmetric generalization of Rindler reference frame and the new kind of u...We aim to study the thermodynamic properties of the spherically symmetric reference frames with uniform acceleration, including the spherically symmetric generalization of Rindler reference frame and the new kind of uniformly accelerated reference frame. We find that, unlike the general studies about the horizon thermodynamics, one cannot obtain the laws of thermodynamics for their horizons in the usual approaches, despite that one can formally define an area entropy （Bekenstein-Hawking entropy）. In fact, the common horizon for a set of uniformly accelerated observers does not always exist, even though the Hawking-Unruh temperature is still well-defined. This result indicates that the Hawking-Unruh temperature is only a kinematic effect, and to gain the laws of thermodynamics for the horizon, one needs the help of dynamics. Our result is in accordance with those from the various studies about the acoustic black holes.展开更多
Quality degradation occurs during transmission of video streaming over the error-prone network. By jointly using redundant slice, reference frame selection, and intra/inters mode decision, a content and end-to-end rat...Quality degradation occurs during transmission of video streaming over the error-prone network. By jointly using redundant slice, reference frame selection, and intra/inters mode decision, a content and end-to-end rate-distortion based error resilience method is proposed. Firstly, the intra/inter mode decision is implemented using macro-block(MB) refresh, and then redundant picture and reference frame selection are utilized together to realize the redundant coding. The estimated error propagation distortion and bit consumption of refresh MB are used for the mode and reference frame decision of refresh MB. Secondly, by analyzing the statistical property in the successive frames, the error propagation distortion and bit consumption are formulated as a function of temporal distance. Encoding parameters of the current frame is determined by the estimated error propagation distortion and bit consumption. Thirdly, by comparing the rate-distortion cost of different combinations, proper selection of error resilience method is performed before the encoding process of the current frame. Finally, the MB mode and bit distribution of the primary picture are analyzed for the derivation of the texture information. The motion information is subsequently incorporated for the calculation of video content complexity to implement the content based redundant coding. Experimental results demonstrate that the proposed algorithm achieves significant performance gains over the LA-RDO and HRP method when video is transmitted over error-prone channel.展开更多
The electrodynamics both in RF with prescribed law of motion and in FR with prescribed structure is considered. Parallel comparison for solutions in “uniformly accelerated” NRF M?ller system and in uniformly acceler...The electrodynamics both in RF with prescribed law of motion and in FR with prescribed structure is considered. Parallel comparison for solutions in “uniformly accelerated” NRF M?ller system and in uniformly accelerated rigid NFR in the space of the constant curvature is carried out. The stationary criterion is formulated. On the basis of this criterion, one of the “eternal physical problems” concerning the field at uniformly accelerated charge motion is considered. The problems of electromagnetic wave spreading, Doppler’s effect and field transformations are discussed.展开更多
A fast local reference frame(LRF)construction method based on the signed surface variation is proposed,which can adapt to the real-time applications such as self-driving,face recognition,object detection.The z-axis of...A fast local reference frame(LRF)construction method based on the signed surface variation is proposed,which can adapt to the real-time applications such as self-driving,face recognition,object detection.The z-axis of the LRF is generated based on the concavity of the local surface of keypoint.The x-axis is constructed by the weighted vector sum of a set of projection vectors of the local neighborhoods around keypoint.The performance of the proposed LRF is evaluated on six standard datasets and compared with six state-of-the-art LRF construction methods(e.g.,BOARD,FLARE,SHOT,RoPS and TOLDI).Experimental results validate the high repeatability,robustness,universality and time efficiency of our method.展开更多
Fractional-order control(FOC)has gained significant attention in power system applications due to their ability to enhance performance and increase stability margins.In grid-connected converter(GCC)systems,the synchro...Fractional-order control(FOC)has gained significant attention in power system applications due to their ability to enhance performance and increase stability margins.In grid-connected converter(GCC)systems,the synchronous reference frame phase-locked loop(SRF-PLL)plays a critical role in grid synchronization for renewable power generation.However,there is a notable research gap regarding the application of FOC to the SRF-PLL.This paper proposes a fractional-order SRF-PLL(FO-SRF-PLL)that incorporates FOC to accurately track the phase angle of the terminal voltage,thereby improving the efficiency of grid-connected control.The dynamic performance of the proposed FO-SRF-PLL is evaluated under varying grid conditions.A comprehensive analysis of the small-signal stability of the GCC system employing the FO-SRF-PLL is also presented,including derived small-signal stability conditions.The results demonstrate that the FO-SRF-PLL significantly enhances robustness against disturbances compared with the conventional SRF-PLL.Furthermore,the GCC system with the FO-SRF-PLL maintains stability even under weak grid conditions,showing superior stability performance over the SRF-PLL.Finally,both simulation and experimental results are provided to validate the analysis and conclusions presented in this paper.展开更多
Numerous practical geodetic and geophysical applications necessitate precise measurements of GNSS displacements at the millimeter or sub-millimeter level. To attain such precision, it is imperative to identify and ana...Numerous practical geodetic and geophysical applications necessitate precise measurements of GNSS displacements at the millimeter or sub-millimeter level. To attain such precision, it is imperative to identify and analyze the unidentified decadal signals inherent in the GPS displacements. In this research, we employ the optimal sequence estimation method to effectively detect an about 13.6-year oscillational signal with an excited amplitude of 3.6±1.2 mm in the U-components of the GPS displacements. It is noteworthy that this signal demonstrates a consistent spatial pattern characterized by the spherical harmonic Y_(2,-2). We conduct a comparative analysis with the 13.6-year oscillation observed in length-of-day variations(and geomagnetic records), finding that they are in reverse phase. After eliminating the Earth's external excitation sources through the utilization of two distinct in-situ hydrological records, we suggest that the 13.6-year GPS signal may come from the internal motions within the Earth. However, the specific excitation source and the detailed physical mechanism remain uncertain. Additionally, we develop a mathematical displacement model to explain the 13.6-year signal. Our findings indicate that this signal can result in displacements of up to 1.37 mm and velocity effects of 0.63 mm/yr(for U-component) at maximum. These results underscore the necessity of incorporating this 13.6-year signal into the construction and maintenance of a dynamic reference frame at the millimeter level.展开更多
The first integrals and their conditions of existence for variable massnonholonomic system in noninertial relerence frames are obtained,and the canonicalequations and the variation equations of the system are extended...The first integrals and their conditions of existence for variable massnonholonomic system in noninertial relerence frames are obtained,and the canonicalequations and the variation equations of the system are extended. It is proved that using the first integral we can construct the integral invariant of the system.Finally,a series of deductions and an example are given.展开更多
The problems of ITRF2008,the latest International Terrestrial Reference Frame,are pointed out and analyzed as follows:(1) ITRF is not a mm-level Terrestrial Reference Frame;(2) the origin of ITRF is neither the Earth&...The problems of ITRF2008,the latest International Terrestrial Reference Frame,are pointed out and analyzed as follows:(1) ITRF is not a mm-level Terrestrial Reference Frame;(2) the origin of ITRF is neither the Earth's center of mass (CM) nor the center of figure (CF);(3) the scale of ITRF is not a uniform system in the sense of the gravitational theory of relativity.These problems result from the linear hypothesis used in the establishment and maintenance of ITRF,which includes the linear hypothesis of the coordinates definition of the ITRF reference stations,and the seven coordinate transformation parameters (three translation parameters,three rotation parameters,and one scale parameter) when the ITRF combine solution is constructed.The linear hypothesis of the ITRF construction leads to the current terrestrial reference frame only at the cm-level,which cannot satisfy the requirements of monitoring mm-level crust movements as well as the global environment.This article points out that the construction of a mm-level Terrestrial Reference Frame is actually a leap from linear to nonlinear.Therefore,according to the main characteristics of nonlinear changes of the crust's deformation,the geocenter motion and the overall height fluctuation of the Earth,the new ITRF station coordinates definition and the new observation equations of combined solutions are constructed for the realization of a mm-level nonlinear ITRF,which can solve the problems of the current ITRF.展开更多
We investigate the role of extended intrinsic mean spin tensor introduced in this work for turbulence modelling in a non-inertial frame of reference. It is described by the Euclidean group of transformations and, in p...We investigate the role of extended intrinsic mean spin tensor introduced in this work for turbulence modelling in a non-inertial frame of reference. It is described by the Euclidean group of transformations and, in particular, its significance and importance in the approach of the algebraic Reynolds stress modelling, such as in a nonlinear K-ε model. To this end and for illustration of the effect of extended intrinsic spin tensor on turbulence modelling, we examine several recently developed nonlinear K-ε models and compare their performance in predicting the homogeneous turbulent shear flow in a rotating frame of reference with LES data. Our results and analysis indicate that, only if the deficiencies of these models and the like be well understood and properly corrected, may in the near future, more sophisticated nonlinear K-ε models be developed to better predict complex turbulent flows in a non-inertial frame of reference.展开更多
基金Industrial Support and Program Project of Universities in Gansu Province(No.2022CYZC-30)National Natural Science Foundation of China(Nos.42430108,41930101)China Scholarship Council(No.202306180085).
文摘We-map is an interactive mobile map that can be easily communicated and applied on personal electronic devices,such as personal computers and mobile phones.Therefore,the study of direction systems and coordinate systems is critical,and exploring reference frames is essential in direction and coordinate systems.Despite its significance,existing research on We-map lacks specific solutions for the exploration of reference frames is indispensable for the establishment of accurate direction and coordinate systems.In this paper,we endeavor to address this gap by elucidating the significance of We-map reference frames,defining them with mathematical constraints,summarizing their nature and characteristics,deriving their transformation relationships and representing them through mathematical formulars and equations.Our work contributes to the fundamental theory of We-map and provides valuable systems and support for the mathematical foundation of We-map,map production,and platform development.Ultimately,this research serves to advance the development of We-map.
基金This study is supported by the National Key Research and Development Program of China(2016YFB0501405)Natural Resources Innovation Platform Construction and Capacity Improvement(A19090)The Fundamental Research Funds for Chinese Academy of Surveying and Mapping(AR1903 and AR2005).
文摘China Geodetic Coordinate System 2000(CGCS2000)has been used for several years as a formal published reference frame.The coordinates of all global navigation satellite system(GNSS)stations in China need to be corrected to align with the CGCS2000 frame.Different strategies can be adopted for the realization of an optimal reference frame.However,different strategies lead to different results,with differences as great as several decimeters when GNSS station coordinates are transformed into CGCS2000-defined coordinates.The two common methods for the coordinate correction of a GNSS station are quasi-stable adjustment under CGCS2000 and plate movement correction,and the differences between their results can be greater than 10 cm.In this study,a statistic method called"supervised clustering"is applied to the selection of GNSS reference stations;a new scheme named"partition spacing"for the grouping of all processed GNSS stations is proposed;and the plate movement correction method is used to correct the coordinates of all GNSS stations from the GNSS epoch to the CGCS2000 epoch.The results from the new partitioning method were found to be significantly better than those from the conventional station-blocking approach.When coordinates from the stations without grouping were used as the standard,the accuracy of all the three-dimensional coordinate components from the new partitioning method was better than 2 mm.The root mean squares(RMSs)of the velocities in the x,y,and z directions resulting from the supervised clustering method were 0.19,0.45,and 0.32 mm∙a1,respectively,which were much smaller than the values of 0.92,0.72,and 0.97 mm∙a1 that resulted from the conventional approach.In addition,singular spectrum analysis(SSA)was used to model and predict the position nonlinear movements.The modeling accuracies of SSA were better than 3,2,and 5 mm in the east(E),north(N),and up(U)directions,respectively;and its prediction accuracies were better than 5 mm and 1 cm for the horizontal and vertical domains,respectively.
基金co-supported by the Open Fund of Joint Key Laboratory of Microsatellite of CAS (No. KFKT15SYS1)the Innovation Foundation of CAS (No. CXJJ-14-Q52)
文摘The drag-free satellites are widely used in the field of fundamental science as they enable the high-precision measurement in pure gravity fields. This paper investigates the estimation of local orbital reference frame(LORF) for drag-free satellites. An approach, taking account of the combination of the minimum estimation error and power spectral density(PSD) constraint in frequency domain, is proposed. Firstly, the relationship between eigenvalues of estimator and transfer function is built to analyze the suppression and amplification effect on input signals and obtain the eigenvalue range. Secondly, an optimization model for state estimator design with minimum estimation error in time domain and PSD constraint in frequency domain is established. It is solved by the sequential quadratic programming(SQP) algorithm. Finally, the orbital reference frame estimation of low-earth-orbit satellite is taken as an example, and the estimator of minimum variance with PSD constraint is designed and analyzed using the method proposed in this paper.
基金Project supported by the Natural Science Foundation of He’nan Province
文摘This paper establishes the integral theory for the dynamics of nonlinear nonholonomic system in noninertial reference frame. Firstly, based on the Routh equation of the relative motion of nonlinear nonholonomic system gives the first integral of the system. Secondly, by using cyclic integral or energy integral reduces the order of the equation and obtains generalized Routh equation and Whittaker equation respectively. Thirdly, derives canonical equation and variation equation and by using the first integral constructs integral invariant. And then, establishes the basic integral variants and the integral invariant of Poincare-Cartan type. Finally, we give a series of deductions.
基金Project supported by the Botswana International University of Science and Technology Research Initiation(Grant Nos.R00015 and S00100)。
文摘We present a three-party reference frame independent quantum key distribution protocol which can be implemented without any alignment of reference frames between the sender and the receiver.The protocol exploits entangled states to establish a secret key among three communicating parties.We derive the asymptotic key rate for the proposed protocol against collective attacks and perform a finite-size key security analysis against general attacks in the presence of statistical fluctuations.We investigate the impact of reference frame misalignment on the stability of our protocol,and we obtain a transmission distance of 180 km,200 km,and 230 km for rotation of reference framesβ=π/6,β=π/8 andβ=0,respectively.Remarkably,our results demonstrate that our proposed protocol is not heavily affected by an increase in misalignment of reference frames as the achievable transmission distances are still comparable to the case where there is no misalignment in reference frames(whenβ=0).We also simulate the performance of our protocol for a fixed number of signals.Our results demonstrate that the protocol can achieve an effective key generation rate over a transmission distance of about 120 km with realistic 107 finite data signals and approximately achieve 195 km with 109 signals.Moreover,our proposed protocol is robust against noise in the quantum channel and achieves a threshold error rate of 22.7%.
基金funded by the research-applied project of the Astronomical Institute of Uzbekistan (FA-A5-F014)
文摘This paper presents an option for modern dynamic terrestrial reference system realization in Uzbekistan for user needs. An additive model is explored to predict patterns of time series and investigate means of constructing forecast time series models in the future. The main components(trend, periodical, and irregular) of the KIUB(DORIS) and KIT3, TASH, MADK, and MTAL(GNSS) international stations coordinate time series were investigated. It was shown that seasonal nonlinear trends occurred both in the height(U) component of all stations and the east(E) component of high mountainous stations such as MTAL and MADK. The seasonal periodical portion of the time series determined from the additive model has a complicated pattern for all sites and can be explained as both hydrological signals in the region and improvement of observational quality. Amplitudes of the best-fitting sinusoids in the North component ranged between 1.73 and 8.76 mm; the East component ranged between 0.82 and 11.92 mm; and the Up component ranged between 3.11 and 40.81 mm. Regression analysis of the irregular portion of the height component of the two techniques at the Kitab station using tropospheric parameters(pressure and temperature) was confirmed as only 57% of the stochastic portion of the time series.
文摘In this paper,a video compressed sensing reconstruction algorithm based on multidimensional reference frames is proposed using the sparse characteristics of video signals in different sparse representation domains.First,the overall structure of the proposed video compressed sensing algorithm is introduced in this paper.The paper adopts a multi-reference frame bidirectional prediction hypothesis optimization algorithm.Then,the paper proposes a reconstruction method for CS frames at the re-decoding end.In addition to using key frames of each GOP reconstructed in the time domain as reference frames for reconstructing CS frames,half-pixel reference frames and scaled reference frames in the pixel domain are also used as CS frames.Reference frames of CS frames are used to obtain higher quality assumptions.Themethod of obtaining reference frames in the pixel domain is also discussed in detail in this paper.Finally,the reconstruction algorithm proposed in this paper is compared with video compression algorithms in the literature that have better reconstruction results.Experiments show that the algorithm has better performance than the best multi-reference frame video compression sensing algorithm and can effectively improve the quality of slowmotion video reconstruction.
文摘This paper presents the generalized principles of least action of variable mass nonholonomic nonconservative system in noninertial reference frame, proves the equivalence between Holder form and Suslov form, and then obtains differential equations of motion of variable mass nonholonomic nonconservative system in noninertial reference frame.
文摘The new variational principle of Gauss's form of nonlinear nonholonomic nonpotential system relative to non-inertial reference frame is established by constructing generalized inertial potentials. Naether's theorem and Naether's inverse theorem of the system above is presented and proved. Finally, one example is given to illustrate the application.
基金This work was supported by the Australian Research Council Laureate Fellowship grant to Z.X.L.(FL150100133)the Key Research Program of the Institute of Geology & Geophysics,CAS,grant to R.N.M.(No. IGGCAS-201905)
文摘Paleogeography can be reconstructed using various crust-or mantle-based reference frames that make fundamentally different assumptions.The various reconstruction models differ significantly in continental paleolongitude,but it has been difficult to assess which models are more valid.We suggest here a "LLSVP test",where an assumed correlation between present-day large low velocity shear-wave provinces and the paleogeography of supercontinent Pangea at breakup ca.200 million years ago can be used to assess the relative accuracy of published reconstructions.Closest correlations between continental paleolongitude and the African LLSVP are achieved with mantle-based reference frames(moving hotspots and true polar wander),whereas shallower crustbased reference frames are shown to be invalid.The relative success of mantle-based frames,and thus the importance of the depth of reference frame,supports the notion that mantle convection is largely vertical compared to the horizontal plate motion of tectonics.
基金supported by the Harris-Galveston Subsidence District(HGSD)the National Science Foundation(NSF)through awards EAR-1242383,DUE-1243582,and OISE1460034
文摘Houston,Texas,is one of the earliest regions to employ continuous GPS technology for land subsidence monitoring.Currently,there are over 200 permanent GPS stations located in the greater Houston area.The need for a consistent and stable reference frame to precisely interpret local ground deformation has become critically important since the 1990s,because of the significant spreading of subsidence.We have established a stable Houston reference frame,designated Houston16,using publicly available GPS observations(>5 years)from 15 Continuously Operating Reference Stations(CORS)located outside of the greater Houston area.Applications of the reference frame in subsidence and faulting studies are demonstrated in this article.Houston16 is aligned in origin and scale with the International GNSS Reference Frame of 2008(IGS08).A 7-parameter method was employed to transform the GPS-derived positional time series from IGS08 to Houston16.The primary product of this study is the seven parameters for transforming Earth-Centered-Earth-Fixed XYZ coordinates from IGS08 to Houston16.The frame stability of Houston16 is approximately 1 mm/year.Houston16 will be updated every few years to mitigate degradation of the frame’s stability with time and to synchronize with future updates of the IGS reference frame.
基金The project supported by National Natural Science Foundation of China under Grant Nos.90403023,10375087,and 10775140
文摘We aim to study the thermodynamic properties of the spherically symmetric reference frames with uniform acceleration, including the spherically symmetric generalization of Rindler reference frame and the new kind of uniformly accelerated reference frame. We find that, unlike the general studies about the horizon thermodynamics, one cannot obtain the laws of thermodynamics for their horizons in the usual approaches, despite that one can formally define an area entropy （Bekenstein-Hawking entropy）. In fact, the common horizon for a set of uniformly accelerated observers does not always exist, even though the Hawking-Unruh temperature is still well-defined. This result indicates that the Hawking-Unruh temperature is only a kinematic effect, and to gain the laws of thermodynamics for the horizon, one needs the help of dynamics. Our result is in accordance with those from the various studies about the acoustic black holes.
基金Project(40927001)supported by the National Natural Science Foundation of ChinaProject(2011R09021-06)supported by the Program of Key Scientific and Technological Innovation Team of Zhejiang Province,ChinaProject supported by the Fundamental Research Funds for the Central Universities of China
文摘Quality degradation occurs during transmission of video streaming over the error-prone network. By jointly using redundant slice, reference frame selection, and intra/inters mode decision, a content and end-to-end rate-distortion based error resilience method is proposed. Firstly, the intra/inter mode decision is implemented using macro-block(MB) refresh, and then redundant picture and reference frame selection are utilized together to realize the redundant coding. The estimated error propagation distortion and bit consumption of refresh MB are used for the mode and reference frame decision of refresh MB. Secondly, by analyzing the statistical property in the successive frames, the error propagation distortion and bit consumption are formulated as a function of temporal distance. Encoding parameters of the current frame is determined by the estimated error propagation distortion and bit consumption. Thirdly, by comparing the rate-distortion cost of different combinations, proper selection of error resilience method is performed before the encoding process of the current frame. Finally, the MB mode and bit distribution of the primary picture are analyzed for the derivation of the texture information. The motion information is subsequently incorporated for the calculation of video content complexity to implement the content based redundant coding. Experimental results demonstrate that the proposed algorithm achieves significant performance gains over the LA-RDO and HRP method when video is transmitted over error-prone channel.
文摘The electrodynamics both in RF with prescribed law of motion and in FR with prescribed structure is considered. Parallel comparison for solutions in “uniformly accelerated” NRF M?ller system and in uniformly accelerated rigid NFR in the space of the constant curvature is carried out. The stationary criterion is formulated. On the basis of this criterion, one of the “eternal physical problems” concerning the field at uniformly accelerated charge motion is considered. The problems of electromagnetic wave spreading, Doppler’s effect and field transformations are discussed.
基金Youth Program of National Natural Science Foundation of China(Nos.41901415,61801481)。
文摘A fast local reference frame(LRF)construction method based on the signed surface variation is proposed,which can adapt to the real-time applications such as self-driving,face recognition,object detection.The z-axis of the LRF is generated based on the concavity of the local surface of keypoint.The x-axis is constructed by the weighted vector sum of a set of projection vectors of the local neighborhoods around keypoint.The performance of the proposed LRF is evaluated on six standard datasets and compared with six state-of-the-art LRF construction methods(e.g.,BOARD,FLARE,SHOT,RoPS and TOLDI).Experimental results validate the high repeatability,robustness,universality and time efficiency of our method.
基金supported in part by the Natural Science Foundation of China(No.52077144)the Youth Innovative Research Team of Science and Technology Scheme,Sichuan Province,China(No.22CXTD0066).
文摘Fractional-order control(FOC)has gained significant attention in power system applications due to their ability to enhance performance and increase stability margins.In grid-connected converter(GCC)systems,the synchronous reference frame phase-locked loop(SRF-PLL)plays a critical role in grid synchronization for renewable power generation.However,there is a notable research gap regarding the application of FOC to the SRF-PLL.This paper proposes a fractional-order SRF-PLL(FO-SRF-PLL)that incorporates FOC to accurately track the phase angle of the terminal voltage,thereby improving the efficiency of grid-connected control.The dynamic performance of the proposed FO-SRF-PLL is evaluated under varying grid conditions.A comprehensive analysis of the small-signal stability of the GCC system employing the FO-SRF-PLL is also presented,including derived small-signal stability conditions.The results demonstrate that the FO-SRF-PLL significantly enhances robustness against disturbances compared with the conventional SRF-PLL.Furthermore,the GCC system with the FO-SRF-PLL maintains stability even under weak grid conditions,showing superior stability performance over the SRF-PLL.Finally,both simulation and experimental results are provided to validate the analysis and conclusions presented in this paper.
基金supported by the National Natural Science Foundation of China (Grant Nos.42388102,42192533,and 42192531)the Fundamental Research Funds for the Central Universities (Grant No.2042023kfyq01)the Special Fund of Hubei Luojia Laboratory (Grant No.220100002)。
文摘Numerous practical geodetic and geophysical applications necessitate precise measurements of GNSS displacements at the millimeter or sub-millimeter level. To attain such precision, it is imperative to identify and analyze the unidentified decadal signals inherent in the GPS displacements. In this research, we employ the optimal sequence estimation method to effectively detect an about 13.6-year oscillational signal with an excited amplitude of 3.6±1.2 mm in the U-components of the GPS displacements. It is noteworthy that this signal demonstrates a consistent spatial pattern characterized by the spherical harmonic Y_(2,-2). We conduct a comparative analysis with the 13.6-year oscillation observed in length-of-day variations(and geomagnetic records), finding that they are in reverse phase. After eliminating the Earth's external excitation sources through the utilization of two distinct in-situ hydrological records, we suggest that the 13.6-year GPS signal may come from the internal motions within the Earth. However, the specific excitation source and the detailed physical mechanism remain uncertain. Additionally, we develop a mathematical displacement model to explain the 13.6-year signal. Our findings indicate that this signal can result in displacements of up to 1.37 mm and velocity effects of 0.63 mm/yr(for U-component) at maximum. These results underscore the necessity of incorporating this 13.6-year signal into the construction and maintenance of a dynamic reference frame at the millimeter level.
文摘The first integrals and their conditions of existence for variable massnonholonomic system in noninertial relerence frames are obtained,and the canonicalequations and the variation equations of the system are extended. It is proved that using the first integral we can construct the integral invariant of the system.Finally,a series of deductions and an example are given.
基金supported by the National Natural Science Foundation of China (Grant No.10603011)the National High Technology Research and Development Program (Grant No.2009AA12Z307)+1 种基金the Science and Technology Commission of Shanghai Municipality (Grant Nos.05QMX1462 and 08ZR1422400)the Youth Foundation of Knowledge Innovation Project of the Chinese Academy of Sciences,Shanghai Astronomical Observatory (Grant No.5120090304)
文摘The problems of ITRF2008,the latest International Terrestrial Reference Frame,are pointed out and analyzed as follows:(1) ITRF is not a mm-level Terrestrial Reference Frame;(2) the origin of ITRF is neither the Earth's center of mass (CM) nor the center of figure (CF);(3) the scale of ITRF is not a uniform system in the sense of the gravitational theory of relativity.These problems result from the linear hypothesis used in the establishment and maintenance of ITRF,which includes the linear hypothesis of the coordinates definition of the ITRF reference stations,and the seven coordinate transformation parameters (three translation parameters,three rotation parameters,and one scale parameter) when the ITRF combine solution is constructed.The linear hypothesis of the ITRF construction leads to the current terrestrial reference frame only at the cm-level,which cannot satisfy the requirements of monitoring mm-level crust movements as well as the global environment.This article points out that the construction of a mm-level Terrestrial Reference Frame is actually a leap from linear to nonlinear.Therefore,according to the main characteristics of nonlinear changes of the crust's deformation,the geocenter motion and the overall height fluctuation of the Earth,the new ITRF station coordinates definition and the new observation equations of combined solutions are constructed for the realization of a mm-level nonlinear ITRF,which can solve the problems of the current ITRF.
文摘We investigate the role of extended intrinsic mean spin tensor introduced in this work for turbulence modelling in a non-inertial frame of reference. It is described by the Euclidean group of transformations and, in particular, its significance and importance in the approach of the algebraic Reynolds stress modelling, such as in a nonlinear K-ε model. To this end and for illustration of the effect of extended intrinsic spin tensor on turbulence modelling, we examine several recently developed nonlinear K-ε models and compare their performance in predicting the homogeneous turbulent shear flow in a rotating frame of reference with LES data. Our results and analysis indicate that, only if the deficiencies of these models and the like be well understood and properly corrected, may in the near future, more sophisticated nonlinear K-ε models be developed to better predict complex turbulent flows in a non-inertial frame of reference.
