Encryption and decryption method of three-dimensional objects uses holograms computer-generated and suggests encoding stage. Information obtained amplitude and phase of a three-dimensional object using mathematically ...Encryption and decryption method of three-dimensional objects uses holograms computer-generated and suggests encoding stage. Information obtained amplitude and phase of a three-dimensional object using mathematically stage transforms overlap stored on a digital computer. Different three-dimensional images restore and develop the system for the expansion of the three-dimensional scenes and camera movement parameters. This article talks about these kinds of digital image processing algorithms as the reconstruction of three-dimensional model of the scene. In the present state, many such algorithms need to be improved in this paper proposing one of the options to improve the accuracy of such reconstruction.展开更多
This paper presents a modified half-sine-squared load model of the jumping impulses for a single person. The model is based on a database of 22,921 experimentally measured single jumping load cycles from 100 test subj...This paper presents a modified half-sine-squared load model of the jumping impulses for a single person. The model is based on a database of 22,921 experimentally measured single jumping load cycles from 100 test subjects. Threedimensional motion capture technology in conjunction with force plates was employed in the experiment to record jumping loads. The variation range and probability distribution of the controlling parameters for the load model such as the impact factor, jumping frequency and contact ratio, are discussed using the experimental data. Correlation relationships between the three parameters are investigated. The contact ratio and jumping frequency are identified as independent model parameters, and an empirical frequency-dependent function is derived for the impact factor. The feasibility of the proposed load model is established by comparing the simulated load curves with measured ones, and by comparing the acceleration responses of a single-degree-of-freedom system to the simulated and measured jumping loads. The results show that a realistic individual jumping load can be generated by the proposed method. This can then be used to assess the dynamic response of assembly structures.展开更多
Covariance matrix plays an important role in risk management, asset pricing, and portfolio allocation. Covariance matrix estimation becomes challenging when the dimensionality is comparable or much larger than the sam...Covariance matrix plays an important role in risk management, asset pricing, and portfolio allocation. Covariance matrix estimation becomes challenging when the dimensionality is comparable or much larger than the sample size. A widely used approach for reducing dimensionality is based on multi-factor models. Although it has been well studied and quite successful in many applications, the quality of the estimated covariance matrix is often degraded due to a nontrivial amount of missing data in the factor matrix for both technical and cost reasons. Since the factor matrix is only approximately low rank or even has full rank, existing matrix completion algorithms are not applicable. We consider a new matrix completion paradigm using the factor models directly and apply the alternating direction method of multipliers for the recovery. Numerical experiments show that the nuclear-norm matrix completion approaches are not suitable but our proposed models and algorithms are promising.展开更多
自改革开放以来,中国经济经历了快速增长,已经成为亚洲第一、世界第二的综合经济体。然而,在世界经济下行、国际形势多变、国内改革经历阵痛的多重背景下,中国宏观经济数据通常呈现出结构突变特征,且不同部门的宏观经济变量具有较强的...自改革开放以来,中国经济经历了快速增长,已经成为亚洲第一、世界第二的综合经济体。然而,在世界经济下行、国际形势多变、国内改革经历阵痛的多重背景下,中国宏观经济数据通常呈现出结构突变特征,且不同部门的宏观经济变量具有较强的联动特征。了解中国宏观经济中的结构突变现象,对于政府部门更好地认知世界经济的运行风险和不确定性,完善宏观经济调控体系,推动宏观经济总体稳定、高质量发展具有重要作用。鉴于此,本文利用含有多个未知结构突变的因子模型对中国23个宏观经济时间序列进行建模,并进一步借鉴Ma and Tu(2023a)中的估计方法对宏观经济数据中的结构突变现象进行分析。结果表明,中国宏观经济数据在1990—2022年一共经历了6次结构突变,其发生的时间点与重大的历史事件紧密相关,例如邓小平南方谈话和党的十四大召开、2003年“非典”疫情、2020年新冠疫情等。此外,与目前研究中国宏观经济结构突变的文献相比,本文得益于因子模型的构造和精准的变点估计方法,能够识别出宏观经济系统中更多的结构变点,更好地刻画中国宏观经济的动态发展。展开更多
The power-expected-posterior prior is used in this paper for comparing nested linear models.The asymptotic behaviour of the method is investigated for different values of the power parameter of the prior.Focus is give...The power-expected-posterior prior is used in this paper for comparing nested linear models.The asymptotic behaviour of the method is investigated for different values of the power parameter of the prior.Focus is given on the consistency of the Bayes factor of comparing the full model M_(p) versus a generic submodel M_(l).In each case,we allow the true generating model to be either M_(p) or M_(l) and we keep the dimension of M_(l) fixed,while the dimension of M_(p) can be either fixed or(grow as)O(n),with n denoting the sample size.展开更多
文摘Encryption and decryption method of three-dimensional objects uses holograms computer-generated and suggests encoding stage. Information obtained amplitude and phase of a three-dimensional object using mathematically stage transforms overlap stored on a digital computer. Different three-dimensional images restore and develop the system for the expansion of the three-dimensional scenes and camera movement parameters. This article talks about these kinds of digital image processing algorithms as the reconstruction of three-dimensional model of the scene. In the present state, many such algorithms need to be improved in this paper proposing one of the options to improve the accuracy of such reconstruction.
基金the National Natural Science Foundation of China under Grant Nos.51178338 and 51478346State Key Laboratory of Disaster Reduction in Civil Engineering under Grant No.SLDRCE14-B-16
文摘This paper presents a modified half-sine-squared load model of the jumping impulses for a single person. The model is based on a database of 22,921 experimentally measured single jumping load cycles from 100 test subjects. Threedimensional motion capture technology in conjunction with force plates was employed in the experiment to record jumping loads. The variation range and probability distribution of the controlling parameters for the load model such as the impact factor, jumping frequency and contact ratio, are discussed using the experimental data. Correlation relationships between the three parameters are investigated. The contact ratio and jumping frequency are identified as independent model parameters, and an empirical frequency-dependent function is derived for the impact factor. The feasibility of the proposed load model is established by comparing the simulated load curves with measured ones, and by comparing the acceleration responses of a single-degree-of-freedom system to the simulated and measured jumping loads. The results show that a realistic individual jumping load can be generated by the proposed method. This can then be used to assess the dynamic response of assembly structures.
基金supported by National Natural Science Foundation of China(Grant Nos.10971122,11101274 and 11322109)Scientific and Technological Projects of Shandong Province(Grant No.2009GG10001012)Excellent Young Scientist Foundation of Shandong Province(Grant No.BS2012SF025)
文摘Covariance matrix plays an important role in risk management, asset pricing, and portfolio allocation. Covariance matrix estimation becomes challenging when the dimensionality is comparable or much larger than the sample size. A widely used approach for reducing dimensionality is based on multi-factor models. Although it has been well studied and quite successful in many applications, the quality of the estimated covariance matrix is often degraded due to a nontrivial amount of missing data in the factor matrix for both technical and cost reasons. Since the factor matrix is only approximately low rank or even has full rank, existing matrix completion algorithms are not applicable. We consider a new matrix completion paradigm using the factor models directly and apply the alternating direction method of multipliers for the recovery. Numerical experiments show that the nuclear-norm matrix completion approaches are not suitable but our proposed models and algorithms are promising.
基金supported by the National Natural Science Foundation of China(12001517,72091212)the USTC Research Funds of the Double First-Class Initiative(YD2040002005)the Fundamental Research Funds for the Central Universities(WK2040000026,WK2040000027)。
文摘自改革开放以来,中国经济经历了快速增长,已经成为亚洲第一、世界第二的综合经济体。然而,在世界经济下行、国际形势多变、国内改革经历阵痛的多重背景下,中国宏观经济数据通常呈现出结构突变特征,且不同部门的宏观经济变量具有较强的联动特征。了解中国宏观经济中的结构突变现象,对于政府部门更好地认知世界经济的运行风险和不确定性,完善宏观经济调控体系,推动宏观经济总体稳定、高质量发展具有重要作用。鉴于此,本文利用含有多个未知结构突变的因子模型对中国23个宏观经济时间序列进行建模,并进一步借鉴Ma and Tu(2023a)中的估计方法对宏观经济数据中的结构突变现象进行分析。结果表明,中国宏观经济数据在1990—2022年一共经历了6次结构突变,其发生的时间点与重大的历史事件紧密相关,例如邓小平南方谈话和党的十四大召开、2003年“非典”疫情、2020年新冠疫情等。此外,与目前研究中国宏观经济结构突变的文献相比,本文得益于因子模型的构造和精准的变点估计方法,能够识别出宏观经济系统中更多的结构变点,更好地刻画中国宏观经济的动态发展。
文摘The power-expected-posterior prior is used in this paper for comparing nested linear models.The asymptotic behaviour of the method is investigated for different values of the power parameter of the prior.Focus is given on the consistency of the Bayes factor of comparing the full model M_(p) versus a generic submodel M_(l).In each case,we allow the true generating model to be either M_(p) or M_(l) and we keep the dimension of M_(l) fixed,while the dimension of M_(p) can be either fixed or(grow as)O(n),with n denoting the sample size.
