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Accelerating SAGE algorithm in PET image reconstruction by rescaled block-iterative method 被引量:1
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作者 朱宏擎 舒华忠 +1 位作者 周健 罗立民 《Journal of Southeast University(English Edition)》 EI CAS 2005年第2期207-210,共4页
A new method to accelerate the convergent rate of the space-alternatinggeneralized expectation-maximization (SAGE) algorithm is proposed. The new rescaled block-iterativeSAGE (RBI-SAGE) algorithm combines the RBI algo... A new method to accelerate the convergent rate of the space-alternatinggeneralized expectation-maximization (SAGE) algorithm is proposed. The new rescaled block-iterativeSAGE (RBI-SAGE) algorithm combines the RBI algorithm with the SAGE algorithm for PET imagereconstruction. In the new approach, the projection data is partitioned into disjoint blocks; eachiteration step involves only one of these blocks. SAGE updates the parameters sequentially in eachblock. In experiments, the RBI-SAGE algorithm and classical SAGE algorithm are compared in theapplication on positron emission tomography (PET) image reconstruction. Simulation results show thatRBI-SAGE has better performance than SAGE in both convergence and image quality. 展开更多
关键词 positron emission tomography space-alternating generalizedexpectation-maximization image reconstruction rescaled block-iterative maximum likelihood
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Comparison of performance between rescaled range analysis and rescaled variance analysis in detecting abrupt dynamic change 被引量:2
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作者 何文平 刘群群 +1 位作者 姜允迪 卢莹 《Chinese Physics B》 SCIE EI CAS CSCD 2015年第4期581-588,共8页
In the present paper, a comparison of the performance between moving cutting data-rescaled range analysis (MC- R/S) and moving cutting data-rescaled variance analysis (MC-V/S) is made. The results clearly indicate... In the present paper, a comparison of the performance between moving cutting data-rescaled range analysis (MC- R/S) and moving cutting data-rescaled variance analysis (MC-V/S) is made. The results clearly indicate that the operating efficiency of the MC-R/S algorithm is higher than that of the MC-V/S algorithm. In our numerical test, the computer time consumed by MC-V/S is approximately 25 times that by MC-R/S for an identical window size in artificial data. Except for the difference in operating efficiency, there are no significant differences in performance between MC-R/S and MC-V/S for the abrupt dynamic change detection. Mc-R/s and MC-V/S both display some degree of anti-noise ability. However, it is important to consider the influences of strong noise on the detection results of MC-R/S and MC-V/S in practical application 展开更多
关键词 moving cutting data-rescaled range analysis moving cutting data-rescaled variance analysis abrupt dynamic change
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沙丘形态动力学数值模拟:以真实空间元胞自动机模型(ReSCAL)为例 被引量:4
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作者 张德国 杨小平 《第四纪研究》 CAS CSCD 北大核心 2017年第2期368-379,共12页
沙丘研究不再局限于现有沉积状态的描述,而是延伸到其形成发育机理的研究。本文通过ReSCAL沙丘模型的数值模拟分析,获得如下结论:1)ReSCAL沙丘模型实现了风况因素影响下复合型沙丘的形成发育过程,揭示了复合沙丘表面次生沙丘形成... 沙丘研究不再局限于现有沉积状态的描述,而是延伸到其形成发育机理的研究。本文通过ReSCAL沙丘模型的数值模拟分析,获得如下结论:1)ReSCAL沙丘模型实现了风况因素影响下复合型沙丘的形成发育过程,揭示了复合沙丘表面次生沙丘形成与星状沙丘翼角延伸的动力机制,提出了沙丘形态与近地表风况之间的互馈机制对近地表风沙流的影响是次生沙丘出现和星状沙丘翼角延伸的重要原因。2)示踪了沙粒的移动轨迹,发现了沙粒每次在沙丘背风坡的埋藏深度具有随机性,使得沙颗粒的平均埋藏时间不同于以往计算的更新时间,继而发现新月形沙丘沙平均埋藏时间等于纵向最大剖面面积与其对应单宽输沙率的比值。3)基于沙丘脊线走向数学方法的发展,并结合ReSCAL沙丘模型的数值模拟结果,发现双向风况模式下,沙源供应能力的变化不仅能塑造不同的沙丘形态,而且能改变沙丘的生长发育模式,甚至是沙丘臂膀的延伸方向(走向)。 展开更多
关键词 沙丘形态动力学 rescal沙丘模型 次生沙丘 星状沙丘 平均埋藏时间 风况 沙源供应能力 沙丘脊线走向
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基于Rescaled Hinge损失函数的多子支持向量机 被引量:6
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作者 李卉 杨志霞 《计算机应用》 CSCD 北大核心 2020年第11期3139-3145,共7页
针对多分类学习模型性能会受异常值影响的问题,提出基于Rescaled Hinge损失函数的多子支持向量机(RHMBSVM)。首先,该方法通过引入有界、非凸的Rescaled Hinge损失函数来构建相应的优化问题;然后,利用共轭函数理论将优化问题作等价变换;... 针对多分类学习模型性能会受异常值影响的问题,提出基于Rescaled Hinge损失函数的多子支持向量机(RHMBSVM)。首先,该方法通过引入有界、非凸的Rescaled Hinge损失函数来构建相应的优化问题;然后,利用共轭函数理论将优化问题作等价变换;最后,使用变量交替策略形成一个迭代算法来求解非凸优化问题,该方法在求解的过程中可自动调节每个样本点的惩罚权重,从而削弱了异常值对K个超平面的影响,增强了鲁棒性。使用5折交叉验证的方法进行数值实验,实验结果表明,在数据集无异常值的情况下,该方法的正确率比多子支持向量机(MBSVM)提升了1.11个百分点,比基于Rescaled Hinge损失函数的鲁棒支持向量机(RSVM-RHHQ)提升了0.74个百分点;在数据集有异常值的情况下,该方法的正确率比MBSVM提升了2.10个百分点,比RSVM-RHHQ提升了1.47个百分点。实验结果证明了所提方法在解决有异常值的多分类问题上的鲁棒性。 展开更多
关键词 机器学习 最优化方法 支持向量机 rescaled Hinge损失函数 多子支持向量机
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Spontaneous combustion influenced by surface methane drainage and its prediction by rescaled range analysis 被引量:1
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作者 Shengqiang Yang Xincheng Hu +2 位作者 Wei Victor Liu Jiawen Cai Xiuhong Zhou 《International Journal of Mining Science and Technology》 SCIE EI CSCD 2018年第2期215-221,共7页
This study established numerical modeling using COMSOLTMto examine the influence of horizontal location and drainage ability of surface borehole on spontaneous combustion in longwall working face gob. Rescaled Range A... This study established numerical modeling using COMSOLTMto examine the influence of horizontal location and drainage ability of surface borehole on spontaneous combustion in longwall working face gob. Rescaled Range Analysis(R/S analysis) was employed to investigate the chaos characteristic of N_2/O_2 ratio from a surface borehole in 10416 working face gob, Yangliu Colliery, China. The simulation results show that there is always a circular ‘‘dissipation zone" around the drainage borehole and an elliptic ‘‘spontaneous combustion zone" in deep gob. Little influence was found on spontaneous combustion zone on the intake side of the gob but the width of spontaneous combustion zone in middle gob is enlarged, while the depth of spontaneous combustion zone near the return side is reduced. The R/S analysis indicates that the influence of surface borehole on spontaneous combustion can be divided into two stages by the chaos feature of N_2/O_2: safety drainage stage and spontaneous combustion initiating stage. It can be concluded that the methane drainage from gob through surface borehole can intervene in the distribution of spontaneous combustion zone in gob and the chaos feature of N_2/O_2 from surface borehole can effectively reflect coal spontaneous combustion condition in gob. 展开更多
关键词 Coal SPONTANEOUS combustion SURFACE drainage BOREHOLE Hurst index rescaled range analysis METHANE drainage SYMBIOTIC DISASTER
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Translocalization and Social Rescaling:Case Studies of Linguistic Landscapes in Guangzhou 被引量:3
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作者 Yanmei HAN Xiaodan Wu 《Chinese Journal of Applied Linguistics》 2020年第1期26-44,126,共20页
Languages and linguistic resources transport from one locality to another,adapting to the norms,customs,and regulations of a new locality.This process involves translocalization.Translocalization emphasizes the moveme... Languages and linguistic resources transport from one locality to another,adapting to the norms,customs,and regulations of a new locality.This process involves translocalization.Translocalization emphasizes the movement of linguistic resources against the backdrop of globalization and the combination or reframing of resources from different localities.This research explores the extent to which translocalization is reflected by the linguistic landscapes of three distinct commercial areas in Guangzhou,China.It goes on to discuss how translocalization works together with social rescaling to incur the movement of linguistic resources and to result in distinct linguistic landscapes of the three commercial areas.It concludes that some languages or linguistic resources,such as English,pinyin and traditional Chinese writing,are transported to local contexts for the purpose of rescaling,whereas other languages or dialects,like Cantonese,might gradually lose their function of rescaling and retain its function in indexing local identity and solidarity.This study calls for more attention to the local resources and contexts in linguistic landscape studies.It argues for the indexical function of linguistic resources in social rescaling and city planning. 展开更多
关键词 linguistic landscape translocalization social rescaling MULTILINGUALISM MANDARIN CANTONESE
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An rescaled range analysis on the characteristics of coal seam development in the Eastern depression of the Liaohe Basin 被引量:2
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作者 Zhao Zhongying Wang Yulin +1 位作者 Liu Guangdi Sun Xiang 《Mining Science and Technology》 EI CAS 2011年第2期223-227,共5页
The characteristics of coal seam development,and the prospects of a favorable coal-forming area,were evaluated for the Liaohe Basin located in China.The Number 3 and Number 9 coal seam thickness series from 60 nearly ... The characteristics of coal seam development,and the prospects of a favorable coal-forming area,were evaluated for the Liaohe Basin located in China.The Number 3 and Number 9 coal seam thickness series from 60 nearly equally spaced bores in the Eastern depression of the Liaohe Basin were examined by a rescaled range analysis.The results indicate that the Hurst exponents of the Number 3 and Number 9 coal seam thickness series are 0.69 and 0.68,respectively.This suggests the presence of persistence.As the bore spacing increases the Hurst exponent of the Number 3 series gradually decreases(H changes from 0.69 to 0.52) and shifts from persistence to randomness.The Hurst exponent of the Number 9 thickness data gradually increases(H changes from 0.68 to 0.91) and always shows the characteristic of persistence.A combination of geological characteristics and the series data allow the conclusion that it is more suitable for the Number 9 coal seam to form in the Northeastern part of the Eastern depression than the Number 3 coal seam. 展开更多
关键词 rescaled range analysis Hurst exponent Coal seam thickness Eastern depression Liaohe Basin
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Langevin approach with rescaled noise for stochastic channel dynamics in Hodgkin–Huxley neurons 被引量:1
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作者 黄艳东 李翔 帅建伟 《Chinese Physics B》 SCIE EI CAS CSCD 2015年第12期74-78,共5页
The Langevin approach has been applied to model the random open and closing dynamics of ion channels. It has long been known that the gate-based Langevin approach is not sufficiently accurate to reproduce the statisti... The Langevin approach has been applied to model the random open and closing dynamics of ion channels. It has long been known that the gate-based Langevin approach is not sufficiently accurate to reproduce the statistics of stochastic channel dynamics in Hodgkin–Huxley neurons. Here, we introduce a modified gate-based Langevin approach with rescaled noise strength to simulate stochastic channel dynamics. The rescaled independent gate and identical gate Langevin approaches improve the statistical results for the mean membrane voltage, inter-spike interval, and spike amplitude. 展开更多
关键词 Langevin approach rescaled noise stochastic channel dynamics Hodgkin–Huxley model
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Resizable, Rescalable and Free-Style Visualization of Hierarchical Clustering and Bioinformatics Analysis 被引量:1
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作者 Ruming Li 《Journal of Data Analysis and Information Processing》 2020年第4期229-240,共12页
Graphical representation of hierarchical clustering results is of final importance in hierarchical cluster analysis of data. Unfortunately, almost all mathematical or statistical software may have a weak capability of... Graphical representation of hierarchical clustering results is of final importance in hierarchical cluster analysis of data. Unfortunately, almost all mathematical or statistical software may have a weak capability of showcasing such clustering results. Particularly, most of clustering results or trees drawn cannot be represented in a dendrogram with a resizable, rescalable and free-style fashion. With the “dynamic” drawing instead of “static” one, this research works around these weak functionalities that restrict visualization of clustering results in an arbitrary manner. It introduces an algorithmic solution to these functionalities, which adopts seamless pixel rearrangements to be able to resize and rescale dendrograms or tree diagrams. The results showed that the algorithm developed makes clustering outcome representation a really free visualization of hierarchical clustering and bioinformatics analysis. Especially, it possesses features of selectively visualizing and/or saving results in a specific size, scale and style (different views). 展开更多
关键词 Hierarchical Clustering Clustering Visualization Dendrogram Drawing Tree Drawing Resizable and rescalable Free-Style Visualization
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Advancements in Numerical Solutions:Fractal Runge-Kutta Approach to Model Time-Dependent MHD Newtonian Fluid with Rescaled Viscosity on Riga Plate
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作者 Muhammad Shoaib Arif Kamaleldin Abodayeh Yasir Nawaz 《Computer Modeling in Engineering & Sciences》 SCIE EI 2024年第11期1213-1241,共29页
Fractal time-dependent issues in fluid dynamics provide a distinct difficulty in numerical analysis due to their complex characteristics,necessitating specialized computing techniques for precise and economical soluti... Fractal time-dependent issues in fluid dynamics provide a distinct difficulty in numerical analysis due to their complex characteristics,necessitating specialized computing techniques for precise and economical solutions.This study presents an innovative computational approach to tackle these difficulties.The main focus is applying the Fractal Runge-Kutta Method to model the time-dependent magnetohydrodynamic(MHD)Newtonian fluid with rescaled viscosity flow on Riga plates.An efficient computational scheme is proposed for handling fractal time-dependent problems in flow phenomena.The scheme is comprised of three stages and constructed using three different time levels.The stability of the scheme is shown by employing the Fourier series analysis to solve scalar problems.The scheme’s convergence is guaranteed for a time fractal partial differential equations system.The scheme is applied to the dimensionless fractal heat and mass transfer model of incompressible,unsteady,laminar,Newtonian fluid with rescaled viscosity flow over the flat and oscillatory Riga plates under the effects of space-and temperature-dependent heat sources.The first-order back differences discretize the continuity equation.The results show that skin friction local Nusselt number declines by raising the coefficient of the temperature-dependent term of heat source and Eckert number.The numerical simulations provide valuable insights into fluid dynamics,explicitly highlighting the influence of the temperature-dependent coefficient of the heat source and the Eckert number on skin friction and local Nusselt number. 展开更多
关键词 Fractal scheme stability convergence fractal Newtonian fluid with rescaled viscosity fluid heat generation
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A rescaling algorithm for multi-relaxation-time lattice Boltzmann method towards turbulent flows with complex configurations
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作者 Haoyang LI Weijian LIU Yuhong DONG 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI CSCD 2023年第9期1597-1612,共16页
Understanding and modeling flows over porous layers are of great industrial significance.To accurately solve the turbulent multi-scale flows on complex configurations,a rescaling algorithm designed for turbulent flows... Understanding and modeling flows over porous layers are of great industrial significance.To accurately solve the turbulent multi-scale flows on complex configurations,a rescaling algorithm designed for turbulent flows with the Chapman-Enskog analysis is proposed.The mesh layout and the detailed rescaling procedure are also introduced.Direct numerical simulations(DNSs)for a turbulent channel flow and a porous walled turbulent channel flow are performed with the three-dimensional nineteen-velocity(D3Q19)multiple-relaxation-time(MRT)lattice Boltzmann method(LBM)to validate the accuracy,adaptability,and computational performance of the present rescaling algorithm.The results,which are consistent with the previous DNS studies based on the finite difference method and the LBM,demonstrate that the present method can maintain the continuity of the macro values across the grid interface and is able to adapt to complex geometries.The reasonable time consumption of the rescaling procedure shows that the present method can accurately calculate various turbulent flows with multi-scale and complex configurations while maintaining high computational efficiency. 展开更多
关键词 slattice Boltzmann method(LBM) direct numerical simulation(DNS) rescaling algorithm complex configuration
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Feature Rescaling of Support Vector Machines 被引量:3
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作者 武征鹏 张学工 《Tsinghua Science and Technology》 SCIE EI CAS 2011年第4期414-421,共8页
Support vector machines (SVMs) have widespread use in various classification problems. Although SVMs are often used as an off-the-shelf tool, there are still some important issues which require improvement such as f... Support vector machines (SVMs) have widespread use in various classification problems. Although SVMs are often used as an off-the-shelf tool, there are still some important issues which require improvement such as feature rescaling. Standardization is the most commonly used feature rescaling method. However, standardization does not always improve classification accuracy. This paper describes two feature rescaling methods: multiple kernel learning-based rescaling (MKL-SVM) and kernel-target alignment-based rescaling (KTA-SVM). MKL-SVM makes use of the framework of multiple kernel learning (MKL) and KTA-SVM is built upon the concept of kernel alignment, which measures the similarity between kernels. The proposed meth- ods were compared with three other methods: an SVM method without rescaling, an SVM method with standardization, and SCADSVM. Test results demonstrate that different rescaling methods apply to different situations and that the proposed methods outperform the others in general. 展开更多
关键词 support vector machines (SVMs) feature rescaling multiple kernel learning (MKL) kernel-targetalignment (KTA)
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The Law of Iterated Logarithm of Rescaled Range Statistics for AR(1) Model 被引量:2
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作者 Zheng Yan LIN Sung Chul LEE 《Acta Mathematica Sinica,English Series》 SCIE CSCD 2006年第2期535-544,共10页
Let {Xn,n ≥ 0} be an AR(1) process. Let Q(n) be the rescaled range statistic, or the R/S statistic for {Xn} which is given by (max1≤k≤n(∑j=1^k(Xj - ^-Xn)) - min 1≤k≤n(∑j=1^k( Xj - ^Xn ))) /(n ^-... Let {Xn,n ≥ 0} be an AR(1) process. Let Q(n) be the rescaled range statistic, or the R/S statistic for {Xn} which is given by (max1≤k≤n(∑j=1^k(Xj - ^-Xn)) - min 1≤k≤n(∑j=1^k( Xj - ^Xn ))) /(n ^-1∑j=1^n(Xj -^-Xn)^2)^1/2 where ^-Xn = n^-1 ∑j=1^nXj. In this paper we show a law of iterated logarithm for rescaled range statistics Q(n) for AR(1) model. 展开更多
关键词 rescaled range statistics Law of iterated logarithm AR(1) model
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The European Muon Collaboration effect from short-range correlated nucleons in a x-rescaling model
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作者 王荣 马娜娜 王涛峰 《Chinese Physics C》 SCIE CAS CSCD 2023年第4期176-183,共8页
In this paper,we examine the hypothesis that the nuclear EMC effect arises merely from the N-N SRC pairs inside the nucleus and that the properties of the N-N SRC pair are universal among the various nuclei,using the ... In this paper,we examine the hypothesis that the nuclear EMC effect arises merely from the N-N SRC pairs inside the nucleus and that the properties of the N-N SRC pair are universal among the various nuclei,using the conventional x-rescaling model for the EMC effect.With the previously determined effective mass of the short-range correlated nucleon and the number of N-N SRC pairs estimated,we calculated the EMC effect of various nuclei within the x-rescaling approach.According to our calculations,the nuclear EMC effect due to the mass deficits of the SRC nucleons is not sufficient to reproduce the observed EMC effect in experiments.We speculate that the internal structure of the mean-field single nucleon is also clearly modified.Alternatively,there can be more origins of the EMC effect beyond the N-N SRC configuration(such as theαcluster),or the universality of N-N SRC pair is significantly violated from light to heavy nuclei. 展开更多
关键词 nucleon-nucleon short-range correlation nuclear EMC effect rescaling model
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气候变化和人类活动下玉米需水量时空特征及未来趋势
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作者 申晓晶 陈猷 +1 位作者 栾文杰 周博 《水土保持学报》 北大核心 2025年第4期243-253,共11页
[目的]为探究气象因素和作物种植面积变化对宁夏引黄灌区玉米需水量的影响及未来玉米需水量变化趋势。[方法]采用Penman-Monteith公式和单作物系数法,计算宁夏引黄灌区玉米需水量并分析其时空变化特征;利用重标极差分析法预测未来作物... [目的]为探究气象因素和作物种植面积变化对宁夏引黄灌区玉米需水量的影响及未来玉米需水量变化趋势。[方法]采用Penman-Monteith公式和单作物系数法,计算宁夏引黄灌区玉米需水量并分析其时空变化特征;利用重标极差分析法预测未来作物需水量和灌溉需水量的时空演变趋势;利用基于偏导数的敏感性分析和对数平均迪氏指数分解方法,探究气象因子和种植面积变化对玉米需水量的影响并确定主要影响因素。[结果]玉米需水量具有较为明显的空间异动性,空间分布趋势呈现由引黄灌区中部向南北两端递增,西南整体低于东北趋势。在对未来需水量预测中,惠农、银川站点的作物未来需水量呈上升趋势。在考虑气象因素对玉米需水量的影响上,相对湿度的敏感系数最高;单位面积作物需水量和灌溉需水量随着最高气温、最低气温、风速、日照时间的上升而增加,随着相对湿度的增加而减少。整个研究期内,作物种植面积变化是导致玉米总需水量变化的主要因素。[结论]玉米种植规模扩大对总需水量的增加有着较大的影响,而气象因子对该时期的总需水量变化作用相对较小。研究结果可为气候变化背景下确定合理的作物种植结构和规模及灌区水资源适应性管理提供决策支持。 展开更多
关键词 气象因子 种植面积变化 需水量 引黄灌区 重标极差分析法(rescaled range analysis R/S) 对数平均迪氏指数分解法(logarithmic mean divisia index LMDI)
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基于尺度重构视角的老旧小区长效运营机制研究——对武汉市“物业城市”模式的实证 被引量:6
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作者 胡洲伟 李志刚 李丽 《自然资源学报》 北大核心 2025年第1期134-146,共13页
住房是城市更新的重要对象,也是联系国民最为紧密、市场价值最为凸显的国土空间资源。当前,大量老旧小区长期缺乏规范运营,面临功能衰退和价值流失的双重困境,各地因此相继开展老旧小区运营探索。其中,武汉市江汉区唐家墩街道“物业城... 住房是城市更新的重要对象,也是联系国民最为紧密、市场价值最为凸显的国土空间资源。当前,大量老旧小区长期缺乏规范运营,面临功能衰退和价值流失的双重困境,各地因此相继开展老旧小区运营探索。其中,武汉市江汉区唐家墩街道“物业城市”模式通过街区一体化运营,实现了老旧小区长效运营,其创新过程有待进一步解释。基于尺度重构视角,剖析了“物业城市”运营实践,研究发现:(1)针对“治理脱嵌”问题,案例地经过多阶段公私合作形成了“五方联动”的社区治理格局;(2)通过运营责任的水平集中和尺度上升,老旧小区被嵌入跨尺度的一体化运营,以统筹不同主体的长短期利益;(3)依托城市公共资产的运营,案例地实现了资金平衡,建立起可支付、微利润、可持续的长效运营机制。研究完善了城市更新事前—事中—事后的分析框架;建议政府对老旧小区提供短期资源支持,推动共治共享,以实现长效运营,进而降低城市更新的频率和支出,促进存量住房资源保值增值。 展开更多
关键词 城市更新 运营机制 老旧小区 “物业城市” 尺度重构 武汉
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尺度重构视域下城市历史地段更新改造的实现机制研究——基于南京小西湖的实证 被引量:5
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作者 李欣 高煜 +1 位作者 冯淑怡 张京祥 《自然资源学报》 北大核心 2025年第1期104-117,共14页
城市更新已成为推动城市高质量发展的重要途径。对于历史城区、历史街区等传统空间而言,因其在产权结构、居民构成、历史文化保护和用地规制等方面的复杂性,许多项目陷入启动难、落地难的现实困境。基于此,以南京小西湖的更新实践为例,... 城市更新已成为推动城市高质量发展的重要途径。对于历史城区、历史街区等传统空间而言,因其在产权结构、居民构成、历史文化保护和用地规制等方面的复杂性,许多项目陷入启动难、落地难的现实困境。基于此,以南京小西湖的更新实践为例,结合尺度重构的理论,分析在历史地段更新中地方政府的有关创新实践及其内在的空间过程对多主体间社会关系的重塑机制。尺度重构策略的系统应用,有助于破解制约中国城市历史地段更新中产权碎化难整合、空间功能难复合、空间降密难实现等关键问题;其内涵的空间过程及对社会关系的重塑,也为进一步修复增长主义引致的城市空间功能单一、经济过度房地产化和社会关系张力大等问题提供了理论支撑和实践指引。 展开更多
关键词 城市更新 尺度重构 空间治理 历史地段 南京小西湖
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国家战略驱动的跨界地区治理重构——以长三角生态绿色一体化发展示范区为例 被引量:1
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作者 唐蜜 罗小龙 +1 位作者 张衔春 杨凌凡 《经济地理》 北大核心 2025年第5期46-56,共11页
文章以尺度重构理论和跨界治理实践为基础,构建国家战略驱动的跨界地区协同治理的分析框架,以长三角生态绿色一体化发展示范区为案例,总结了中央和地方共同推动跨界地区协同治理的内在逻辑及关键路径。结果表明:(1)国家战略驱动的跨界... 文章以尺度重构理论和跨界治理实践为基础,构建国家战略驱动的跨界地区协同治理的分析框架,以长三角生态绿色一体化发展示范区为案例,总结了中央和地方共同推动跨界地区协同治理的内在逻辑及关键路径。结果表明:(1)国家战略驱动的跨界地区协同治理,本质上是国家通过战略赋权进行指导监督、由地方政府具体实施的柔性治理,旨在突破行政区治理思维下跨界地区的发展困境。在该模式中,国家在重构跨界地区话语体系的同时,也保留了地方在规划实施中的裁量空间,这种多层级主体跨界协同治理的模式具有渐进性和稳定性。(2)在跨界地区治理的过程中,中央政府尝试通过重构空间治理体系调和地方关系和优化地方利益分配,最终解决跨界治理事务缺乏地方政府重视、地方间竞争激烈和跨界地区治理权力行政分割等问题。在此过程中,跨界地区不仅成为国家推动地方政府事权调整的战略安排,还转型为国家和地方共同推进治理重构的空间表达。(3)国家主要借助话语体系重构、治理主体架构重构、治理权力重构3个手段构建多层级跨界治理网络,以纵向行政主体权力重组、横向地方竞合关系重构和地方间的责权关系调整为重点,针对性地解决跨界地区的分割发展问题。在中央政府动员和地方政府积极响应下,跨界地区实现了纵向的尺度跃迁和横向的要素跨界融合,进而在实现国家治理意图的同时保障了地方间利益的合理分配。 展开更多
关键词 跨界地区 省际毗邻地区 尺度重构 行政壁垒 区域治理 长三角
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基于土壤分形的探地雷达三维随机介质建模
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作者 郭昰龙 鹿琪 +1 位作者 刘四新 梁文婧 《地球物理学进展》 北大核心 2025年第5期2201-2210,共10页
探地雷达(Ground Penetrating Radar,GPR)已经被广泛的应用于土壤结构、土壤含水量和土壤质地的探测中.本文利用土壤分形特征建立三维随机介质模型,并进行GPR正演模拟.随机介质的非均匀性由三维分形布朗运动(Fractal Brownian Motion,F... 探地雷达(Ground Penetrating Radar,GPR)已经被广泛的应用于土壤结构、土壤含水量和土壤质地的探测中.本文利用土壤分形特征建立三维随机介质模型,并进行GPR正演模拟.随机介质的非均匀性由三维分形布朗运动(Fractal Brownian Motion,FBM)谱密度函数来描述,并着重讨论了Hurst指数和尺度系数对模型的影响.Hurst指数是FBM的一个重要指标,它反映了介质的光滑以及扰动程度,同时Hurst指数也被用来描述土壤的自相似性,即分形程度.土壤含水量(Soil Water Content,SWC)是影响土壤介质异质性的关键因素,土壤介电性质也取决于SWC.因此,本文利用SWC数据通过R/S分析法获得Hurst指数.最后,通过有限时域差分法(Finite-Difference Time-Domain,FDTD)对建立的三维随机介质模型进行了GPR正演模拟.模拟结果表明,本文提出的基于土壤分形的随机介质建模方法可为GPR土壤探测提供有效的建模工具. 展开更多
关键词 探地雷达 土壤分形 三维随机介质 HURST指数 R/S分析
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基于时空特征的视频压缩自适应缩放方法 被引量:1
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作者 吴佩颖 沈礼权 《工业控制计算机》 2025年第2期102-104,共3页
深度学习技术越来越多地集成到视频压缩框架中,并显著提高了压缩效率。然而,现有方法受限于两点:一是忽略了重缩放过程中不同特征冗余间的相互作用,难以有效促进压缩;二是当前方法通常对所有类型的帧采用统一缩放方法,导致关键信息丢失... 深度学习技术越来越多地集成到视频压缩框架中,并显著提高了压缩效率。然而,现有方法受限于两点:一是忽略了重缩放过程中不同特征冗余间的相互作用,难以有效促进压缩;二是当前方法通常对所有类型的帧采用统一缩放方法,导致关键信息丢失。为了解决上述问题,提出一种基于时空特征的重缩放框架,该框架包括时空去冗余网络和自适应缩放网络。时空去冗余网络根据帧的特性动态选择去冗余方法,消除关键帧的空域冗余和非关键帧的时域冗余,并保留了关键细节,为后续的帧预测提供了丰富的信息。自适应缩放网络实现输入输出双向映射,确保缩放和编码过程中信息的连续性和完整性。实验结果显示,与编解码器锚点相比,该框架在低时延配置下实现15.73%的BDBR降低,证明了所提算法的有效性。 展开更多
关键词 视频压缩 时空冗余 视频缩放
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