In addressing the challenge of motion artifacts in Positron Emission Tomography (PET) lung scans, our studyintroduces the Triple Equivariant Motion Transformer (TEMT), an innovative, unsupervised, deep-learningbasedfr...In addressing the challenge of motion artifacts in Positron Emission Tomography (PET) lung scans, our studyintroduces the Triple Equivariant Motion Transformer (TEMT), an innovative, unsupervised, deep-learningbasedframework for efficient respiratory motion correction in PET imaging. Unlike traditional techniques,which segment PET data into bins throughout a respiratory cycle and often face issues such as inefficiency andoveremphasis on certain artifacts, TEMT employs Convolutional Neural Networks (CNNs) for effective featureextraction and motion decomposition.TEMT’s unique approach involves transforming motion sequences into Liegroup domains to highlight fundamental motion patterns, coupled with employing competitive weighting forprecise target deformation field generation. Our empirical evaluations confirm TEMT’s superior performancein handling diverse PET lung datasets compared to existing image registration networks. Experimental resultsdemonstrate that TEMT achieved Dice indices of 91.40%, 85.41%, 79.78%, and 72.16% on simulated geometricphantom data, lung voxel phantom data, cardiopulmonary voxel phantom data, and clinical data, respectively. Tofacilitate further research and practical application, the TEMT framework, along with its implementation detailsand part of the simulation data, is made publicly accessible at https://github.com/yehaowei/temt.展开更多
Objective:To explore the corrective effect of posterior chamber intraocular lens implantation with phakic eyes in the treatment of high myopia and astigmatism.Methods:From May 2023,the hospital began to collect the ca...Objective:To explore the corrective effect of posterior chamber intraocular lens implantation with phakic eyes in the treatment of high myopia and astigmatism.Methods:From May 2023,the hospital began to collect the case data of diagnosis and treatment of high myopia and astigmatism.By May 2024,310 cases were included,all of which were treated with posterior chamber intraocular lens implantation.The visual acuity,astigmatism and axial position of the intraocular lens were observed before and after treatment.Results:At different time points after the operation,the patient’s vision was significantly improved compared with that before the operation(P<0.05),and the vision level was equal to or greater than the best-corrected vision before the operation.At different time points after the operation,the average rotation of the intraocular lens was less than 5 degrees.Astigmatism was significantly lower than that before the operation(P<0.05).After the operation,the intraocular pressure increased in 11 cases,accounting for 3.55%,with no adverse complications such as lens turbidity,glare and obvious halo occurring.Conclusion:The posterior chamber intraocular lens implantation with phakic eyes has an ideal correction effect in the treatment of high myopia and astigmatism,which can effectively improve the vision level of patients and reduce the degree of astigmatism,and has high effectiveness and safety.展开更多
To correct spectral peak drift and obtain more reliable net counts,this study proposes a long short-term memory(LSTM)model fused with a convolutional neural network(CNN)to accurately estimate the relevant parameters o...To correct spectral peak drift and obtain more reliable net counts,this study proposes a long short-term memory(LSTM)model fused with a convolutional neural network(CNN)to accurately estimate the relevant parameters of a nuclear pulse signal by learning of samples.A predefined mathematical model was used to train the CNN-LSTM model and generate a dataset composed of distorted pulse sequences.The trained model was validated using simulated pulses.The relative errors in the amplitude estimation of pulse sequences with different degrees of distortion were obtained using triangular shaping,CNN-LSTM,and LSTM models.As a result,for severely distorted pulses,the relative error of the CNN-LSTM model in estimating the pulse parameters was reduced by 14.35%compared with that of the triangular shaping algorithm.For slightly distorted pulses,the relative error of the CNN-LSTM model was reduced by 0.33%compared with that of the triangular shaping algorithm.The model was then evaluated considering two performance indicators,the correction ratio and the efficiency ratio,which represent the proportion of the increase in peak area of the two characteristic peak regions of interest(ROIs)to the peak area of the corrected characteristic peak ROI and the proportion of the increase in peak area of the two characteristic peak ROIs to the peak areas of the two shadow peak ROI,respectively.Ten measurement results of the iron ore samples indicate that approximately 86.27%of the decreased peak area of the shadow peak ROI was corrected to the characteristic peak ROI,and the proportion of the corrected peak area to the peak area of the characteristic peak ROI was approximately 1.72%.The proposed CNN-LSTM model can be applied to X-ray energy spectrum correction,which is of great significance for X-ray spectroscopy and elemental content analyses.展开更多
In allusion to the problem of friction,leakage,vibration and noise existing in continuous rotary motor electro-hydraulic servo system,highly nonlinearity and uncertainties affecting the system performance,based on the...In allusion to the problem of friction,leakage,vibration and noise existing in continuous rotary motor electro-hydraulic servo system,highly nonlinearity and uncertainties affecting the system performance,based on the transfer function of electro-hydraulic servo system,a kind of Pol-Ind friction model is proposed.The parameters of Pol-Ind friction model are identified and the accurate mathematical model of friction torque is obtained by experiment.The self-correcting wavelet neural network(WNN)controller is proposed,and Adam optimization algorithm is used to perform gradient optimization on scale factor and displacement factor in wavelet basis function,so as to improve the speed and precision of parameter optimization.Through comparative simulation analysis,it is clearly that the self-correcting WNN controller can effectively improve the frequency response and tracking accuracy of continuous rotary motor electro-hydraulic servo system.展开更多
When the electronic temperature sensor was incorporated into a system of soil water tension and the insidetube temperature was monitored in real time, it is concluded that the inside temperature increased by 26.9 ℃ a...When the electronic temperature sensor was incorporated into a system of soil water tension and the insidetube temperature was monitored in real time, it is concluded that the inside temperature increased by 26.9 ℃ and the inside pressure changed about 14.6 Kpa, when the pottery soil was replaced by the sealing plug. When the soil water was relatively stable in the experimental salvers, the in-side pressure stil varied regularly with the temperature. When the inside temperature increased by 22.2 ℃, the inside pressure varied about 7.4 Kpa. Through com-pensation calculation of the inside tension, the temperature in the warming and cooling periods was compensated, which was useful to correct the tension measurement errors induced from the changing temperature. When the measuring interval was 4 hours and the temperature difference was 18.1 ℃, the tension difference of both points was only 0.278 Kpa, compared to the difference up to 6.5 Kpa before compensation.展开更多
The ionospheric time delay is one of the main error sources in C/A code GPS navigation and positioning applications. In this paper, a method is proposed for real-time dual-frequency ionospheric time-delay correcting u...The ionospheric time delay is one of the main error sources in C/A code GPS navigation and positioning applications. In this paper, a method is proposed for real-time dual-frequency ionospheric time-delay correcting using a C/A code GPS receiver, and the principle of the circuit block diagram for this method is analyzed with its feasibility theoretically demonstrated.展开更多
When tubules regularly arranged are welded onto a bobbin by robot, the position and orientation of some tubules may be changed by such factors as thermal deformations and positioning errors etc. Which make it very dif...When tubules regularly arranged are welded onto a bobbin by robot, the position and orientation of some tubules may be changed by such factors as thermal deformations and positioning errors etc. Which make it very difficult to weld automatically and continuously by the method of teaching and playing. In this paper, a kind of error measuring system is presented. By which the position and orientation errors of tubules relative to the teaching one can be measured. And, a method to correct the locus errors is also proposed, by which the moving locus planned via teaching points can be corrected in real time according to measured error parameters. So that, just by teaching one, all tubules on a bobbin could be welded automatically.展开更多
The mean correcting martingale measure for the stochastic process defined as the exponential of an additive process is constructed. Necessary and sufficient conditions for the existence of mean correcting martingale a...The mean correcting martingale measure for the stochastic process defined as the exponential of an additive process is constructed. Necessary and sufficient conditions for the existence of mean correcting martingale are also obtained. The investigation of this paper will establish a unified way that is applicable both to the case of Ldvy processes and that of the sums of independent random variables. As an application, we present the necessary and sufficient conditions that the discounted stock price process is a martingale.展开更多
In this paper, we present a novel technique based on a mixed Error Correcting Code(ECC)-the convolutional code and the repetition code to enhance the robustness of the embedded watermark. Before embedding, the binary ...In this paper, we present a novel technique based on a mixed Error Correcting Code(ECC)-the convolutional code and the repetition code to enhance the robustness of the embedded watermark. Before embedding, the binary watermark is scanned to one-dimension sequence and later inputted into the (3, 1, 2) convolutional encoder and (3, 1) repetition encoder frame by frame, which will improve the error correcting capability of decoder. The output code sequence is scanned to some matrixes as the new watermark messages. The watermarking is selected in low frequency band of the Discrete Wavelet Transform (DWT) and therefore it can resist the destruction of image processing. Experimental results are presented to demonstrate that the robustness of a watermark with mixed ECC is much higher than the traditional one just with repetition coding while suffering JPEG lossy compression, salt and pepper noise and center cutting processing.展开更多
An effective method was proposed for correcting the seasonal—interannual prediction of the summer climate anomaly. The predictive skill can be substantially improved by applying the method to the seasonal—interannua...An effective method was proposed for correcting the seasonal—interannual prediction of the summer climate anomaly. The predictive skill can be substantially improved by applying the method to the seasonal—interannual prediction carried out by a coupled ocean—atmosphere model. Thus the method has the potential to improve the operational summer climate predictions. Key words Correction, Seasonal-interannual prediction - Quasi-biennial signal This research was supported by the National Key Programme for Developing Basic Sciences under Contract G1998040905-2 and the key project “ The Analytical Study on the Seasonal and Interannual Variability of the General Atmospheric Circulation (1998-2001)” of National Natural Science Foundation of China under Contract 49735160.展开更多
In the course of vehicle license plate （VLP） automatic recognition, tilt correction is a very crucial process. According to Karhunen-Loeve （K-L） transformation, the coordinates of characters in the image are arran...In the course of vehicle license plate （VLP） automatic recognition, tilt correction is a very crucial process. According to Karhunen-Loeve （K-L） transformation, the coordinates of characters in the image are arranged into a two-dimensional covariance matrix, on the basis of which the centered process is carried out. Then, the eigenvector and the rotation angle α are computed in turn. The whole image is rotated by -α. Thus, image horizontal tilt correction is performed. In the vertical tilt correction process, three correction methods, which are K-L transformation method, the line fitting method based on K -means clustering （LFMBKC）, and the line fitting based on least squares （LFMBLS）, are put forward to compute the vertical tilt angle θ. After shear transformation （ST） is imposed on the rotated image, the final correction image is obtained. The experimental results verify that this proposed method can be easily implemented, and can quickly and accurately get the tilt angle. It provides a new effective way for the VLP image tilt correction as well.展开更多
Forty-eight cases of malposition of fetus were treated by electro-acupuncture, using Zhiyin (UB 67) points. 39 cases were corrected with a rate of 81.3%, the average session of treatment being 1.41. Two control groups...Forty-eight cases of malposition of fetus were treated by electro-acupuncture, using Zhiyin (UB 67) points. 39 cases were corrected with a rate of 81.3%, the average session of treatment being 1.41. Two control groups were set up: moxibustion and blank control group. Statistical analysis shows that efficacy of electro-acupuncture is markedly superior to that of the blank. Sessions of electro-acupuncture were less than that of moxibustion and the difference was statistically significant, though there is no significant difference of efficacy between the two groups.展开更多
To evaluate the results of the TRAFIX instrumentation in correcting s coliosis. Methods. Since October 1997, 47 patients with scoliosis received spinal fixation with the TRAFIX instrumentation at the Peking Union Medi...To evaluate the results of the TRAFIX instrumentation in correcting s coliosis. Methods. Since October 1997, 47 patients with scoliosis received spinal fixation with the TRAFIX instrumentation at the Peking Union Medical College Hospital. T he average age was 14.3 years (range 10 to 38 years). There were 27 idiopathic c ases, 16 congenital cases, 2 cases with Marfan syndrome and 2 with neurofibromat osis. Twelve of the 47 patients underwent anterior release, while 4 patients rec eived the revision approach. The average follow up time was 26 months (13～38 m onths). Results. The measurements of primary coronal deformity before and after surgery were 74°(50°～115°) and 38.7° (11°～95°), respectively. The average curve correction was 54%. The average number of fused segments was 12.5 (7～17) verte brae. The distance between the center of apex and the C7 plumb line was 56.8 mm before surgery (25～107mm) and 31 mm after surgery (10～87mm). Conclusion. The TRAFIX instrumentation provides three dimensional correction wi th refinement, convenience and reliable fixation.展开更多
Rain is one of the main sources of error in dual-frequency altimeter Jason-1 wind measurement. In this study, a new radar altimeter backscatter model is proposed and validated to eliminate rain effects. The model take...Rain is one of the main sources of error in dual-frequency altimeter Jason-1 wind measurement. In this study, a new radar altimeter backscatter model is proposed and validated to eliminate rain effects. The model takes into account attenuation, volume backscattering, and sea surface perturbation by raindrops under rain conditions. A match-up dataset is built to evaluate rain effects, in combination with the Jason-1 normalized radar cross section, precipitation radar data from the Tropical Rainfall Measuring Mission, and sea surface wind reanalysis data from the European Centre for Medium-Range Weather Forecasts. The results show that rain-induced surface perturbation backscatter increases with rain rate at Ku-band, but their correlation at C-band is poor. In addition, rain surface perturbation and attenuation have major effects on radar altimeter wind measurements. Finally, a rain correction model for Jason-1 winds is developed and validation results prove its ability to reduce rain-induced inaccuracies in wind retrievals.展开更多
A set of absorption curves was priorly prepared on transparent films to fit the background and peak intensities in continuous scanning X-ray stress measurement.It may be better to correct both background and absorptio...A set of absorption curves was priorly prepared on transparent films to fit the background and peak intensities in continuous scanning X-ray stress measurement.It may be better to correct both background and absorption of pure diffraction intensity.Experimental results revealed this to be a reliable correction method.展开更多
The even degree of chicken population could be estimated by the coefficient of variation or the percentage of the chicken whose body weights were not higher and lower than average body weight by 15% in the sampling po...The even degree of chicken population could be estimated by the coefficient of variation or the percentage of the chicken whose body weights were not higher and lower than average body weight by 15% in the sampling population.In fact,the two indexes were relative to each other.On the basis of analyzing the relationship between the two expectations,the expectations which had been worked out independently were corrected in this paper.展开更多
A new Chien search method for shortened Reed-Solomon （RS） code is proposed, based on this, a versatile RS decoder for correcting both errors and erasures is designed. Compared with the traditional RS decoder, the we...A new Chien search method for shortened Reed-Solomon （RS） code is proposed, based on this, a versatile RS decoder for correcting both errors and erasures is designed. Compared with the traditional RS decoder, the weighted coefficient of the Chien search method is calculated sequentially through the three pipelined stages of the decoder. And therefore, the computation of the errata locator polynomial and errata evaluator polynomial needs to be modified. The versatile RS decoder with minimum distance 21 has been synthesized in the Xilinx Virtex-Ⅱ series field programmable gate array （FPGA） xe2v1000-5 and is used by coneatenated coding system for satellite communication. Results show that the maximum data processing rate can be up to 1.3 Gbit/s.展开更多
One of the main drivers for intelligent transportation systems is safety. Adaptive cruise control, as a common solution for traffic safety, lias extended from radars to cameras. Due to high mobility of vehicles and un...One of the main drivers for intelligent transportation systems is safety. Adaptive cruise control, as a common solution for traffic safety, lias extended from radars to cameras. Due to high mobility of vehicles and unevenness of roads, the picture quality of cameras has been great challenges for camera-based adaptive cruise control. In this paper, an image distortion correction algorithm is addressed. Our method is based on optical flow technology which is normally applied in motion estimation and video compression research. We are the first to attempt to adapt it in image distortion correction. Two optical flow approaches, the Lucas-Kanade method and the Horn-Schunck method, are selected and compared. The procedure of image distortion correction using the optical flow method has been tested by both synthetic test images and camera images. The experimental results show that the Lucas-Kanade method is more suitable in the correction of image distortion.展开更多
Structured light,where complex optical fields are tailored in all their degrees of freedom,has become highly topical of late,advanced by a sophisticated toolkit comprising both linear and nonlinear optics.Removing und...Structured light,where complex optical fields are tailored in all their degrees of freedom,has become highly topical of late,advanced by a sophisticated toolkit comprising both linear and nonlinear optics.Removing undesired structure from light is far less developed,leveraging mostly on inverting the distortion,e.g.,with adaptive optics or the inverse transmission matrix of a complex channel,both requiring that the distortion be fully characterized through appropriate measurement.We show that distortions in spatially structured light can be corrected through difference-frequency generation in a nonlinear crystal without any need for the distortion to be known.We demonstrate the versatility of our approach using a wide range of aberrations and structured light modes,including higher-order orbital angular momentum(OAM)beams,showing excellent recovery of the original undistorted field.To highlight the efficacy of this process,we deploy the system in a prepare-and-measure communications link with OAM,showing minimal cross talk even when the transmission channel is highly aberrated,and outline how the approach could be extended to alternative experimental modalities and nonlinear processes.Our demonstration of light-correcting light without the need for measurement opens an approach to measurement-free error correction for classical and quantum structured light,with direct applications in imaging,sensing,and communication.展开更多
At present,we are in the noisy-intermediate-scale-quantum era of quantum information science and technology[1],in which there are relatively large numbers of qubits with noise.For instance,the error rate of current su...At present,we are in the noisy-intermediate-scale-quantum era of quantum information science and technology[1],in which there are relatively large numbers of qubits with noise.For instance,the error rate of current superconducting qubits is orders of magnitude away from practical application.To solve this problem,various methods have been used,such as holonomic quantum gate[2],dynamical decoupling[3],entanglement purification[4],and quantum error correction[5].展开更多
基金the National Natural Science Foundation of China(No.82160347)Yunnan Provincial Science and Technology Department(No.202102AE090031)Yunnan Key Laboratory of Smart City in Cyberspace Security(No.202105AG070010).
文摘In addressing the challenge of motion artifacts in Positron Emission Tomography (PET) lung scans, our studyintroduces the Triple Equivariant Motion Transformer (TEMT), an innovative, unsupervised, deep-learningbasedframework for efficient respiratory motion correction in PET imaging. Unlike traditional techniques,which segment PET data into bins throughout a respiratory cycle and often face issues such as inefficiency andoveremphasis on certain artifacts, TEMT employs Convolutional Neural Networks (CNNs) for effective featureextraction and motion decomposition.TEMT’s unique approach involves transforming motion sequences into Liegroup domains to highlight fundamental motion patterns, coupled with employing competitive weighting forprecise target deformation field generation. Our empirical evaluations confirm TEMT’s superior performancein handling diverse PET lung datasets compared to existing image registration networks. Experimental resultsdemonstrate that TEMT achieved Dice indices of 91.40%, 85.41%, 79.78%, and 72.16% on simulated geometricphantom data, lung voxel phantom data, cardiopulmonary voxel phantom data, and clinical data, respectively. Tofacilitate further research and practical application, the TEMT framework, along with its implementation detailsand part of the simulation data, is made publicly accessible at https://github.com/yehaowei/temt.
文摘Objective:To explore the corrective effect of posterior chamber intraocular lens implantation with phakic eyes in the treatment of high myopia and astigmatism.Methods:From May 2023,the hospital began to collect the case data of diagnosis and treatment of high myopia and astigmatism.By May 2024,310 cases were included,all of which were treated with posterior chamber intraocular lens implantation.The visual acuity,astigmatism and axial position of the intraocular lens were observed before and after treatment.Results:At different time points after the operation,the patient’s vision was significantly improved compared with that before the operation(P<0.05),and the vision level was equal to or greater than the best-corrected vision before the operation.At different time points after the operation,the average rotation of the intraocular lens was less than 5 degrees.Astigmatism was significantly lower than that before the operation(P<0.05).After the operation,the intraocular pressure increased in 11 cases,accounting for 3.55%,with no adverse complications such as lens turbidity,glare and obvious halo occurring.Conclusion:The posterior chamber intraocular lens implantation with phakic eyes has an ideal correction effect in the treatment of high myopia and astigmatism,which can effectively improve the vision level of patients and reduce the degree of astigmatism,and has high effectiveness and safety.
基金This work was supported by the Open Project of the Guangxi Key Laboratory of Nuclear Physics and Nuclear Technology(No.NLK2022-05)Central Government Guidance Funds for Local Scientific and Technological Development,China(No.Guike ZY22096024)+3 种基金Sichuan Natural Science Youth Fund Project(No.2023NSFSC1366)Open Research Fund of the National Engineering Research Center for Agro-Ecological Big Data Analysis&Application,Anhui University(No.AE202209)Research Fund of Guangxi Key Lab of Multi-source Information Mining&Security(MIMS22-04)National Natural Science Youth Foundation of China(No.12305214).
文摘To correct spectral peak drift and obtain more reliable net counts,this study proposes a long short-term memory(LSTM)model fused with a convolutional neural network(CNN)to accurately estimate the relevant parameters of a nuclear pulse signal by learning of samples.A predefined mathematical model was used to train the CNN-LSTM model and generate a dataset composed of distorted pulse sequences.The trained model was validated using simulated pulses.The relative errors in the amplitude estimation of pulse sequences with different degrees of distortion were obtained using triangular shaping,CNN-LSTM,and LSTM models.As a result,for severely distorted pulses,the relative error of the CNN-LSTM model in estimating the pulse parameters was reduced by 14.35%compared with that of the triangular shaping algorithm.For slightly distorted pulses,the relative error of the CNN-LSTM model was reduced by 0.33%compared with that of the triangular shaping algorithm.The model was then evaluated considering two performance indicators,the correction ratio and the efficiency ratio,which represent the proportion of the increase in peak area of the two characteristic peak regions of interest(ROIs)to the peak area of the corrected characteristic peak ROI and the proportion of the increase in peak area of the two characteristic peak ROIs to the peak areas of the two shadow peak ROI,respectively.Ten measurement results of the iron ore samples indicate that approximately 86.27%of the decreased peak area of the shadow peak ROI was corrected to the characteristic peak ROI,and the proportion of the corrected peak area to the peak area of the characteristic peak ROI was approximately 1.72%.The proposed CNN-LSTM model can be applied to X-ray energy spectrum correction,which is of great significance for X-ray spectroscopy and elemental content analyses.
基金Supported by the National Natural Science Foundation of China(No.51975164)the China Scholarship Council(No.201908230358)the Fundamental Research Fundation for Universities of Heilongjiang Province。
文摘In allusion to the problem of friction,leakage,vibration and noise existing in continuous rotary motor electro-hydraulic servo system,highly nonlinearity and uncertainties affecting the system performance,based on the transfer function of electro-hydraulic servo system,a kind of Pol-Ind friction model is proposed.The parameters of Pol-Ind friction model are identified and the accurate mathematical model of friction torque is obtained by experiment.The self-correcting wavelet neural network(WNN)controller is proposed,and Adam optimization algorithm is used to perform gradient optimization on scale factor and displacement factor in wavelet basis function,so as to improve the speed and precision of parameter optimization.Through comparative simulation analysis,it is clearly that the self-correcting WNN controller can effectively improve the frequency response and tracking accuracy of continuous rotary motor electro-hydraulic servo system.
基金Supported by Jiangsu Agricultural Self-innovation Fund[CX(13)3031]~~
文摘When the electronic temperature sensor was incorporated into a system of soil water tension and the insidetube temperature was monitored in real time, it is concluded that the inside temperature increased by 26.9 ℃ and the inside pressure changed about 14.6 Kpa, when the pottery soil was replaced by the sealing plug. When the soil water was relatively stable in the experimental salvers, the in-side pressure stil varied regularly with the temperature. When the inside temperature increased by 22.2 ℃, the inside pressure varied about 7.4 Kpa. Through com-pensation calculation of the inside tension, the temperature in the warming and cooling periods was compensated, which was useful to correct the tension measurement errors induced from the changing temperature. When the measuring interval was 4 hours and the temperature difference was 18.1 ℃, the tension difference of both points was only 0.278 Kpa, compared to the difference up to 6.5 Kpa before compensation.
文摘The ionospheric time delay is one of the main error sources in C/A code GPS navigation and positioning applications. In this paper, a method is proposed for real-time dual-frequency ionospheric time-delay correcting using a C/A code GPS receiver, and the principle of the circuit block diagram for this method is analyzed with its feasibility theoretically demonstrated.
文摘When tubules regularly arranged are welded onto a bobbin by robot, the position and orientation of some tubules may be changed by such factors as thermal deformations and positioning errors etc. Which make it very difficult to weld automatically and continuously by the method of teaching and playing. In this paper, a kind of error measuring system is presented. By which the position and orientation errors of tubules relative to the teaching one can be measured. And, a method to correct the locus errors is also proposed, by which the moving locus planned via teaching points can be corrected in real time according to measured error parameters. So that, just by teaching one, all tubules on a bobbin could be welded automatically.
基金Supported by the Foundation for Innovative Research Groups of the National Natural Science Foundation of China(71221061)National Natural Science Foundation of China(11171101)+3 种基金National Social Science Fund of China(11BTJ01115BJY122)Social Sciences Foundation of Ministry of Education of China(12YJAZH173)Aid program for Science and Technology Innovative Research Team in Higher Educational Institutions of Hunan Province
文摘The mean correcting martingale measure for the stochastic process defined as the exponential of an additive process is constructed. Necessary and sufficient conditions for the existence of mean correcting martingale are also obtained. The investigation of this paper will establish a unified way that is applicable both to the case of Ldvy processes and that of the sums of independent random variables. As an application, we present the necessary and sufficient conditions that the discounted stock price process is a martingale.
文摘In this paper, we present a novel technique based on a mixed Error Correcting Code(ECC)-the convolutional code and the repetition code to enhance the robustness of the embedded watermark. Before embedding, the binary watermark is scanned to one-dimension sequence and later inputted into the (3, 1, 2) convolutional encoder and (3, 1) repetition encoder frame by frame, which will improve the error correcting capability of decoder. The output code sequence is scanned to some matrixes as the new watermark messages. The watermarking is selected in low frequency band of the Discrete Wavelet Transform (DWT) and therefore it can resist the destruction of image processing. Experimental results are presented to demonstrate that the robustness of a watermark with mixed ECC is much higher than the traditional one just with repetition coding while suffering JPEG lossy compression, salt and pepper noise and center cutting processing.
基金National Key Programme for Developing Basic Sciences under Contract!G1998040905--2 The Analytical Study on the Seasonal and
文摘An effective method was proposed for correcting the seasonal—interannual prediction of the summer climate anomaly. The predictive skill can be substantially improved by applying the method to the seasonal—interannual prediction carried out by a coupled ocean—atmosphere model. Thus the method has the potential to improve the operational summer climate predictions. Key words Correction, Seasonal-interannual prediction - Quasi-biennial signal This research was supported by the National Key Programme for Developing Basic Sciences under Contract G1998040905-2 and the key project “ The Analytical Study on the Seasonal and Interannual Variability of the General Atmospheric Circulation (1998-2001)” of National Natural Science Foundation of China under Contract 49735160.
基金supported by Scientific Research Fund of Hunan Province, PRC (No. 07JJ6141)Scientific Research Fund of Hunan Provincial Education Department, PRC (No. 06C582)
文摘In the course of vehicle license plate （VLP） automatic recognition, tilt correction is a very crucial process. According to Karhunen-Loeve （K-L） transformation, the coordinates of characters in the image are arranged into a two-dimensional covariance matrix, on the basis of which the centered process is carried out. Then, the eigenvector and the rotation angle α are computed in turn. The whole image is rotated by -α. Thus, image horizontal tilt correction is performed. In the vertical tilt correction process, three correction methods, which are K-L transformation method, the line fitting method based on K -means clustering （LFMBKC）, and the line fitting based on least squares （LFMBLS）, are put forward to compute the vertical tilt angle θ. After shear transformation （ST） is imposed on the rotated image, the final correction image is obtained. The experimental results verify that this proposed method can be easily implemented, and can quickly and accurately get the tilt angle. It provides a new effective way for the VLP image tilt correction as well.
文摘Forty-eight cases of malposition of fetus were treated by electro-acupuncture, using Zhiyin (UB 67) points. 39 cases were corrected with a rate of 81.3%, the average session of treatment being 1.41. Two control groups were set up: moxibustion and blank control group. Statistical analysis shows that efficacy of electro-acupuncture is markedly superior to that of the blank. Sessions of electro-acupuncture were less than that of moxibustion and the difference was statistically significant, though there is no significant difference of efficacy between the two groups.
文摘To evaluate the results of the TRAFIX instrumentation in correcting s coliosis. Methods. Since October 1997, 47 patients with scoliosis received spinal fixation with the TRAFIX instrumentation at the Peking Union Medical College Hospital. T he average age was 14.3 years (range 10 to 38 years). There were 27 idiopathic c ases, 16 congenital cases, 2 cases with Marfan syndrome and 2 with neurofibromat osis. Twelve of the 47 patients underwent anterior release, while 4 patients rec eived the revision approach. The average follow up time was 26 months (13～38 m onths). Results. The measurements of primary coronal deformity before and after surgery were 74°(50°～115°) and 38.7° (11°～95°), respectively. The average curve correction was 54%. The average number of fused segments was 12.5 (7～17) verte brae. The distance between the center of apex and the C7 plumb line was 56.8 mm before surgery (25～107mm) and 31 mm after surgery (10～87mm). Conclusion. The TRAFIX instrumentation provides three dimensional correction wi th refinement, convenience and reliable fixation.
基金Supported by the Knowledge Innovation Program of Chinese Academy of Sciences (No.Y0S04300KB)the Major Program for the Research Equipment of Chinese Academy of Sciences (No.YZ200946)
文摘Rain is one of the main sources of error in dual-frequency altimeter Jason-1 wind measurement. In this study, a new radar altimeter backscatter model is proposed and validated to eliminate rain effects. The model takes into account attenuation, volume backscattering, and sea surface perturbation by raindrops under rain conditions. A match-up dataset is built to evaluate rain effects, in combination with the Jason-1 normalized radar cross section, precipitation radar data from the Tropical Rainfall Measuring Mission, and sea surface wind reanalysis data from the European Centre for Medium-Range Weather Forecasts. The results show that rain-induced surface perturbation backscatter increases with rain rate at Ku-band, but their correlation at C-band is poor. In addition, rain surface perturbation and attenuation have major effects on radar altimeter wind measurements. Finally, a rain correction model for Jason-1 winds is developed and validation results prove its ability to reduce rain-induced inaccuracies in wind retrievals.
文摘A set of absorption curves was priorly prepared on transparent films to fit the background and peak intensities in continuous scanning X-ray stress measurement.It may be better to correct both background and absorption of pure diffraction intensity.Experimental results revealed this to be a reliable correction method.
基金Financed by the Heilongjiang province natural science fund
文摘The even degree of chicken population could be estimated by the coefficient of variation or the percentage of the chicken whose body weights were not higher and lower than average body weight by 15% in the sampling population.In fact,the two indexes were relative to each other.On the basis of analyzing the relationship between the two expectations,the expectations which had been worked out independently were corrected in this paper.
基金Sponsored by the Ministerial Level Advanced Research Foundation (20304)
文摘A new Chien search method for shortened Reed-Solomon （RS） code is proposed, based on this, a versatile RS decoder for correcting both errors and erasures is designed. Compared with the traditional RS decoder, the weighted coefficient of the Chien search method is calculated sequentially through the three pipelined stages of the decoder. And therefore, the computation of the errata locator polynomial and errata evaluator polynomial needs to be modified. The versatile RS decoder with minimum distance 21 has been synthesized in the Xilinx Virtex-Ⅱ series field programmable gate array （FPGA） xe2v1000-5 and is used by coneatenated coding system for satellite communication. Results show that the maximum data processing rate can be up to 1.3 Gbit/s.
文摘One of the main drivers for intelligent transportation systems is safety. Adaptive cruise control, as a common solution for traffic safety, lias extended from radars to cameras. Due to high mobility of vehicles and unevenness of roads, the picture quality of cameras has been great challenges for camera-based adaptive cruise control. In this paper, an image distortion correction algorithm is addressed. Our method is based on optical flow technology which is normally applied in motion estimation and video compression research. We are the first to attempt to adapt it in image distortion correction. Two optical flow approaches, the Lucas-Kanade method and the Horn-Schunck method, are selected and compared. The procedure of image distortion correction using the optical flow method has been tested by both synthetic test images and camera images. The experimental results show that the Lucas-Kanade method is more suitable in the correction of image distortion.
基金the funding from the Department of Science and Innovation as well as the National Research Foundation in South AfricaSupport from the Italian Ministry of Research(MUR)through the PRIN 2017 project“Interacting photons in polariton circuits”(INPho POL)and the PNRR MUR project PE0000023-NQSTI is acknowledgedsupport from the Italian Space Agency through the“Highdimensional quantum information”project
文摘Structured light,where complex optical fields are tailored in all their degrees of freedom,has become highly topical of late,advanced by a sophisticated toolkit comprising both linear and nonlinear optics.Removing undesired structure from light is far less developed,leveraging mostly on inverting the distortion,e.g.,with adaptive optics or the inverse transmission matrix of a complex channel,both requiring that the distortion be fully characterized through appropriate measurement.We show that distortions in spatially structured light can be corrected through difference-frequency generation in a nonlinear crystal without any need for the distortion to be known.We demonstrate the versatility of our approach using a wide range of aberrations and structured light modes,including higher-order orbital angular momentum(OAM)beams,showing excellent recovery of the original undistorted field.To highlight the efficacy of this process,we deploy the system in a prepare-and-measure communications link with OAM,showing minimal cross talk even when the transmission channel is highly aberrated,and outline how the approach could be extended to alternative experimental modalities and nonlinear processes.Our demonstration of light-correcting light without the need for measurement opens an approach to measurement-free error correction for classical and quantum structured light,with direct applications in imaging,sensing,and communication.
文摘At present,we are in the noisy-intermediate-scale-quantum era of quantum information science and technology[1],in which there are relatively large numbers of qubits with noise.For instance,the error rate of current superconducting qubits is orders of magnitude away from practical application.To solve this problem,various methods have been used,such as holonomic quantum gate[2],dynamical decoupling[3],entanglement purification[4],and quantum error correction[5].
