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Construction theory of dyadic scale function and dyadic wavelet function
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作者 冉启文 冯英浚 孙学全 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2000年第4期25-27,共3页
We derive the conditions for the existence of the unique solution of the two scale integral equation and the form of the solution, according to the method of the construction of the dyadic scale function. We give the ... We derive the conditions for the existence of the unique solution of the two scale integral equation and the form of the solution, according to the method of the construction of the dyadic scale function. We give the construction of the dyadic wavelet and its necessary and sufficient condition. As an application, we also develop a pyramid algorithm of the dyadic wavelet decomposition. 展开更多
关键词 two scale INTEGRAL equation DYADIC WAVELET function DYADIC scale function PYRAMID algorithm
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Stable computations of the spherically layered media theory with high lossy media by using scaled Bessel functions
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作者 Jia-Hui Wang Bo O.Zhu 《Journal of Electronic Science and Technology》 2025年第1期22-34,共13页
The spherically layered media theory has wide applications for electromagnetic wave scattering analysis.Due to the involved Bessel functions,the conventional formulations of spherically layered media theory suffer fro... The spherically layered media theory has wide applications for electromagnetic wave scattering analysis.Due to the involved Bessel functions,the conventional formulations of spherically layered media theory suffer from numerical overflow or underflow when the Bessel function’s order is large,the argument is small or the argument has a large imaginary part.The first two issues have been solved recently by employing small-argument asymptotic formulas of Bessel functions,while the third issue remains unsolved.In this paper,the Bessel functions in the conventional formulation of the theory are replaced by scaled Bessel functions which have good numerical properties for high loss media,and stable formulas are derived.Numerical tests show that this approach can work properly with very high lossy media.Also,this approach can be seamlessly combined with the stable computation method for cases of small argument and large order of Bessel functions. 展开更多
关键词 Lossy media Numerical stability scaled Bessel function Spherically layered media theory
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POLY-SCALE REFINABLE FUNCTION AND THEIR PROPERTIES
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作者 杨守志 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 2006年第12期1687-1695,共9页
Poly-scale refinable function with dilation factor a is introduced. The existence of solution of poly-scale refinable equation is investigated. Specially, necessary and sufficient conditions for the orthonormality of ... Poly-scale refinable function with dilation factor a is introduced. The existence of solution of poly-scale refinable equation is investigated. Specially, necessary and sufficient conditions for the orthonormality of solution function Ф of poly-scale refinable equation with integer dilation factor a are established. Some properties of poly-scale refinable function are discussed. Several examples illustrating how to use the method to construct poly-scale refinable function are given. 展开更多
关键词 poly-scale function dilation factor poly-scale functional equation
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Gait and Glasgow Coma Scale scores can predict functional recovery in patients with traumatic brain injury 被引量:3
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作者 Sevil Bilgin Arzu Guclu-Gunduz +2 位作者 Hakan Oruckaptan Nezire Kose Bülent Celik 《Neural Regeneration Research》 SCIE CAS CSCD 2012年第25期1978-1984,共7页
Fifty-one patients with mild (n -- 14), moderate (n = 10) and severe traumatic brain injury (n = 27) received early rehabilitation. Level of consciousness was evaluated using the Glasgow Coma Score Functional le... Fifty-one patients with mild (n -- 14), moderate (n = 10) and severe traumatic brain injury (n = 27) received early rehabilitation. Level of consciousness was evaluated using the Glasgow Coma Score Functional level was determined using the Glasgow Outcome Score, whilst mobility was evaluated using the Mobility Scale for Acute Stroke. Activities of daily living were assessed using the Barthel Index. Following Bobath neurodevelopmental therapy, the level of consciousness was significantly improved in patients with moderate and severe traumatic brain injury, but was not greatly influenced in patients with mild traumatic brain injury. Mobility and functional level were significantly improved in patients with mild, moderate and severe traumatic brain injury. Gait recovery was more obvious in patients with mild traumatic brain injury than in patients with moderate and severe traumatic brain injury. Activities of daily living showed an improvement but this was insignificant except for patients with severe traumatic brain injury. Nevertheless, complete recovery was not acquired at discharge. Multiple regression analysis showed that gait and Glasgow Coma Scale scores can be considered predictors of functional outcomes following traumatic brain injury. 展开更多
关键词 brain injury traumatic brain injury REHABILITATION early rehabilitation function PROGNOSIS GlasgowComa scale Glasgow Outcome scale functional level neural regeneration
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Multi-scale analysis of the spatial structure of China’s major function zoning 被引量:9
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作者 WANG Yafei FAN Jie 《Journal of Geographical Sciences》 SCIE CSCD 2020年第2期197-211,共15页
The spatial structures of China’s Major Function Zoning are important constraining indicators in all types of spatial planning and key parameters for accurately downscaling major functions.Taking the proportion of ur... The spatial structures of China’s Major Function Zoning are important constraining indicators in all types of spatial planning and key parameters for accurately downscaling major functions.Taking the proportion of urbanization zones,agricultural development zones and ecological security zones as the basic parameter,this paper explores the spatial structures of major function zoning at different scales using spatial statistics,spatial modeling and landscape metrics methods.The results show:First,major function zones have spatial gradient structures,which are prominently represented by latitudinal and longitudinal gradients,a coastal distance gradient,and an eastern-central-western gradient.Second,the pole-axis system structure and core-periphery structure exist at provincial scales.The general principle of the pole-axis structure is that as one moves along the distance axis,the proportion of urbanization zones decreases and the proportion of ecological security zones increases.This also means that the proportion of different function zones has a ring-shaped spatial differentiation principle with distance from the core.Third,there is a spatial mosaic structure at the city and county scale.This spatial mosaic structure has features of both spatial heterogeneity,such as agglomeration and dispersion,as well as of mutual,adjacent topological correlation and spatial proximity.The results of this study contribute to scientific knowledge on major function zones and the principles of spatial organization,and it acts as an important reference for China’s integrated geographical zoning. 展开更多
关键词 China major function zoning MULTI-scale spatial gradient pole-axis CORE-PERIPHERY spatial mosaic
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Positively Worded Subscale Score of the Perceived Stress Scale Is Associated with Cognitive Domain Function
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作者 Julie M. Jiang Elizabeth K. Seng +2 位作者 Molly E. Zimmerman Mimi Kim Richard B. Lipto 《Journal of Behavioral and Brain Science》 2017年第7期311-324,共14页
Objectives: To examine the cross-sectional associations of the separate subscales of the Perceived Stress Scale (PSS) and tests measuring cognitive domains in older adults. Methods: 897 adults over the age of 70 free ... Objectives: To examine the cross-sectional associations of the separate subscales of the Perceived Stress Scale (PSS) and tests measuring cognitive domains in older adults. Methods: 897 adults over the age of 70 free of amnestic mild cognitive impairment and dementia and enrolled in the Einstein Aging Study made up the study sample. The PSS-14 was used to measure stress. Three cognitive domains (language, episodic memory, and frontal-executive) had previously been found using principle component analysis. Linear regression analyses were used to determine the relationship between the PSS subscales and cognitive domain function. Results: The study sample had a mean age of 79.1 years and 62.8% were female. Bivariate correlations show that the PSS-14 positively worded subscale of the PSS (PSS-PW) was significantly associated with all three cognitive domains (language: r = -0.15, p < 0.001;episodic memory: r = -0.16, p < 0.001;frontal-executive: r = -0.21, p <0.001) while the negatively worded subscale of the PSS (PSS-NW) was not significantly associated with any cognitive domain. In linear regression analyses adjusted for age, white race, gender, years of education, and depressive symptoms, the PSS-PW remained significantly associated with each of the cognitive domains. The PSS-NW was not associated with any cognitive domains in any model. The PSS-14 was significantly associated with language and episodic memory, but not the frontal-executive domain. Conclusion: Worse PSS-PW scores are associated with reduced cognitive function in the executive, memory, and language domains in nondemented older adults. The PSS-PW subscale correlated better with cognitive function than the overall PSS-14. Future research should evaluate the temporality of the association and if stress reduction therapies improve cognitive performance. 展开更多
关键词 PERCEIVED STRESS scale Cognitive Domain function CROSS-SECTIONAL PERCEIVED STRESS scale Subscales
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GU'S FUNCTION SCALE OF ION HYDRATION FORCE AND CHARGE SIZE
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作者 顾宏堪 《Chinese Journal of Oceanology and Limnology》 SCIE CAS CSCD 1997年第2期186-191,共6页
Water Vapor Chemistry" as a new science was discovered and established from trace analysis in Gu’s laboratory(Gu, 1991; Gu et al., 1991). Gu’s Function shows that the trace metal ion concentration in water vapo... Water Vapor Chemistry" as a new science was discovered and established from trace analysis in Gu’s laboratory(Gu, 1991; Gu et al., 1991). Gu’s Function shows that the trace metal ion concentration in water vapor has positive correlation to"specific electron affinity constant"last ionization potential Iz/ion valence Z and negative correlation to ion volume V and coordination number N(Gu, 1994). Gu’s Func-tion C=f[(Iz/Z)/VN]of the bond parameter in water vapor chemistry corresponds to the potential energy function Z’ e2/r in the Schrodinger Equation of quantum chemistry. In different ions with the same 2+ charge, the ion concentration of water-water vapor transfer may be much different. This shows that the 2+ charge of different ions has different attractive force (hydration force). This different attractive force of the charge can be scaled with the relative energy or charge size from Gu’s Function. 展开更多
关键词 water vapor chemistry Gu′s function scale ION hydration FORCE ION CHARGE SIZE
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Quadratic Lyapunov Function and Exponential Dichotomy on Time Scales
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作者 ZHANG JI LIU ZHEN-XIN 《Communications in Mathematical Research》 CSCD 2011年第1期24-36,共13页
In this paper, we study the relationship between exponential dichotomy and quadratic Lyapunov function for the linear equation x△=A(t)x on time scales. Moreover, for the nonlinear perturbed equation x△= A(t)x ... In this paper, we study the relationship between exponential dichotomy and quadratic Lyapunov function for the linear equation x△=A(t)x on time scales. Moreover, for the nonlinear perturbed equation x△= A(t)x + f(t, x) we give the instability of the zero solution when f is sufficiently small. 展开更多
关键词 quadratic Lyapunov function exponential dichotomy time scale INSTABILITY
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EXISTENCE OF PERIODIC SOLUTIONS TO A SYSTEM WITH FUNCTIONAL RESPONSE ON TIME SCALES
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作者 Zhenjie Liu 《Analysis in Theory and Applications》 2009年第4期369-380,共12页
This paper investigates the existence of periodic solutions of a three-species food-chain diffusive system with Beddington-DeAngelis functional responses and time delays in a two-patch environment on time scales. By u... This paper investigates the existence of periodic solutions of a three-species food-chain diffusive system with Beddington-DeAngelis functional responses and time delays in a two-patch environment on time scales. By using a continuation theorem based on coincidence degree theory, we obtain sufficient criteria for the existence of periodic solutions for the system. Moreover, when the time scale T is chosen as R or Z, the existence of the periodic solutions of the corresponding continuous and discrete models follows. Therefore, the method is unified to provide the existence of the desired solutions for continuous differential equations and discrete difference equations. 展开更多
关键词 time scale food-chain system Beddington-DeAngelis functional response diffusion coincidence degree
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基于改进YOLO11n模型的自动驾驶道路交通检测算法研究
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作者 田晟 赵凯龙 苗佳霖 《广西师范大学学报(自然科学版)》 北大核心 2026年第1期1-9,共9页
随着自动驾驶技术的快速发展,道路交通检测作为感知模块的核心任务,直接影响自动驾驶系统的安全性与可靠性,当前基于深度学习方法作为研究的热点,却仍存在检测精度低、模型泛化性差等问题。为解决这些问题,本文提出一种改进YOLO11n模型... 随着自动驾驶技术的快速发展,道路交通检测作为感知模块的核心任务,直接影响自动驾驶系统的安全性与可靠性,当前基于深度学习方法作为研究的热点,却仍存在检测精度低、模型泛化性差等问题。为解决这些问题,本文提出一种改进YOLO11n模型的道路交通检测方法。该方法通过增加小目标检测层提高对小目标的检测精度,引入GhostConv+DWConv检测头结构,组合优化现有的双DWConv结构,并设计更适合小目标的Inner-CIoU损失函数,增强模型的泛化性,提高边界框回归的准确性。实验结果显示,与现有YOLO11n算法相比,该模型在KITTI和BDD100K数据集上的检测精度分别提升1.1个百分点和1.9个百分点,并达到125帧/s和124帧/s的检测速度,提升了低分辨率小目标检测的有效性,在不同交通场景下具有良好的泛化性。 展开更多
关键词 自动驾驶 小目标检测 YOLO11 多尺度检测 损失函数
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基于脑电多尺度特征和图神经网络的紧急制动行为识别
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作者 闫光辉 黄霄 常文文 《浙江大学学报(工学版)》 北大核心 2026年第2期404-414,共11页
现有技术主要依赖传统的时频域特征,对脑活动空间域特征的研究不足.为了实现对紧急制动意图和正常驾驶的分类识别,提出融合多尺度卷积、脑功能网络和图卷积神经网络的新模型.利用多尺度卷积提取时频域融合的多尺度特征;基于脑功能连接... 现有技术主要依赖传统的时频域特征,对脑活动空间域特征的研究不足.为了实现对紧急制动意图和正常驾驶的分类识别,提出融合多尺度卷积、脑功能网络和图卷积神经网络的新模型.利用多尺度卷积提取时频域融合的多尺度特征;基于脑功能连接测量矩阵构建脑功能网络,得到空间图结构信息;采用图卷积神经网络融合多尺度特征和空间图结构信息,实现对紧急制动脑电信号的分类识别.实验结果表明,所提模型在公开数据集上多被试的准确率均超过93.00%,最高达到95.60%;在单被试条件下,准确率均超过92.00%,最高达到98.94%.消融实验验证了所提模型各模块均对模型性能的提升具有显著贡献.在相同数据集下,所提模型比已有的6种脑电信号分类算法更具优势. 展开更多
关键词 紧急制动 脑电信号(EEG) 多尺度特征 脑功能网络 图卷积神经网络
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Evaluation of Differential Item Functioning of the Center of Epidemiological Scale Depression Revisited for Gender in Mexican Adolescents
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作者 Jesus Rafael Osomo Mungula Herminia Beatriz Segura Celis Ochoa +1 位作者 Alma Gloria Vallejo Casarin Patricia Andrade Palos 《Psychology Research》 2013年第4期232-241,共10页
关键词 性别差异 流行病学 抑郁症 青少年 墨西哥 评价 研究人员 项目运作
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A Note on an Economic Lot-sizing Problem with Perishable Inventory and Economies of Scale Costs:Approximation Solutions and Worst Case Analysis 被引量:2
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作者 Qing-Guo Bai Yu-Zhong Zhang Guang-Long Dong 《International Journal of Automation and computing》 EI 2010年第1期132-136,共5页
This paper presents an economic lot-sizing problem with perishable inventory and general economies of scale cost functions. For the case with backlogging allowed, a mathematical model is formulated, and several proper... This paper presents an economic lot-sizing problem with perishable inventory and general economies of scale cost functions. For the case with backlogging allowed, a mathematical model is formulated, and several properties of the optimal solutions are explored. With the help of these optimality properties, a polynomial time approximation algorithm is developed by a new method. The new method adopts a shift technique to obtain a feasible solution of subproblem and takes the optimal solution of the subproblem as an approximation solution of our problem. The worst case performance for the approximation algorithm is proven to be (4√2 + 5)/7. Finally, an instance illustrates that the bound is tight. 展开更多
关键词 Economic lot-sizing problem BACKLOGGING economies of scale function PERISHABLE approximation algorithm
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聚丙烯蜂窝材料的改性和吸附空气污染物性能
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作者 黄超强 曾贵峰 +4 位作者 姬文晋 程高 窦永深 刘三毛 李永峰 《精细化工》 北大核心 2026年第1期94-102,共9页
以聚丙烯(PP)蜂窝材料(50 mm×25 mm×20 mm)为基底,在涂覆技术的基础上,先制备了铝氧化物改性PP蜂窝材料,并进一步引入Zn^(2+)、Fe^(3+)、Cu^(2+)、Mg^(2+)和Ca^(2+)等金属离子进行改性。采用SEM、EDS、BET和FTIR对其进行了表... 以聚丙烯(PP)蜂窝材料(50 mm×25 mm×20 mm)为基底,在涂覆技术的基础上,先制备了铝氧化物改性PP蜂窝材料,并进一步引入Zn^(2+)、Fe^(3+)、Cu^(2+)、Mg^(2+)和Ca^(2+)等金属离子进行改性。采用SEM、EDS、BET和FTIR对其进行了表征。考察了PP蜂窝材料孔径、造孔剂(尿素)浓度、金属离子浓度、浸渍时间对铝氧化物和金属离子改性PP蜂窝材料氨气吸附性能的影响,并对Ca^(2+)改性PP蜂窝材料、Fe^(3+)改性PP蜂窝材料分别在100 L和30 m^(3)实验舱中的连续氨气吸附性能进行了评价。结果表明,在以孔径2.0 mm的PP蜂窝材料、浓度2.6 mol/L铝溶胶溶液、浓度0.1 mol/L尿素、浓度0.3 mol/L Ca^(2+)或Fe^(3+)溶液、浸渍涂覆时间为10 min的条件下,制备的铝氧化物改性PP蜂窝材料比表面积为9.9 m^(2)/g,60 min内氨气饱和吸附容量为22.2 g/L;Ca^(2+)改性PP蜂窝材料和Fe^(3+)改性PP蜂窝材料60 min内氨气饱和吸附容量分别为27.7和30.0 g/L,三甲胺的吸附容量分别为12.6和15.3 g/L;经热处理再生后,铝氧化物改性PP蜂窝材料、Ca^(2+)改性PP蜂窝材料和Fe^(3+)改性PP蜂窝材料的氨气吸附性能不变。在100 L实验舱中,Ca^(2+)改性PP蜂窝材料10 min内的氨气(18.8 mmol/m^(3))去除率为99.41%,12次循环使用后氨气(70~100 mmol/m^(3))去除率>90%,而Fe^(3+)改性PP蜂窝材料60 min氨气去除率>95%,经过3次使用后,其氨气去除率仍>90%。 展开更多
关键词 聚丙烯蜂窝 铝氧化物 金属离子 空气污染物 放大实验 功能材料
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一种抗遮挡重叠与尺度变化的行人检测算法
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作者 马晞茗 李宁 吴迪 《现代电子技术》 北大核心 2026年第1期41-48,共8页
针对复杂人群密集场景中因行人目标受遮挡和行人目标尺度不一等因素导致行人检测器检测精度下降、漏检率变高的问题,基于Faster R-CNN算法进行改进,提出一种抗遮挡重叠与尺度变化的行人检测算法。在特征提取环节,设计一种融合注意力机... 针对复杂人群密集场景中因行人目标受遮挡和行人目标尺度不一等因素导致行人检测器检测精度下降、漏检率变高的问题,基于Faster R-CNN算法进行改进,提出一种抗遮挡重叠与尺度变化的行人检测算法。在特征提取环节,设计一种融合注意力机制的循环多尺度特征提取网络,用于学习更为丰富细致的多尺度特征信息,并重点聚焦于关键特征信息,提升网络对不同尺度行人目标的灵敏度;对于损失函数模块,引入斥力损失以降低目标相互遮挡对检测造成的干扰;在后处理环节,设计一种基于遮挡重叠率补偿的非极大值抑制算法,使得实际的抑制阈值能够随着遮挡程度的变化而自适应调整,从而进一步降低密集处行人目标的漏检率。实验结果表明:改进后算法的检测性能更为出色,在CrowdHuman和CityPersons数据集上的检测平均精度相比基准算法分别提升了2.5%和1.9%,对数平均漏检率分别降低了3.5%和3.2%,在TJU-DHD-pedestrian数据集上不同尺度行人目标的对数平均漏检率也得到较为明显的降低,所提算法可以适用于复杂场景中的行人检测。 展开更多
关键词 行人检测 人群密集场景 Faster R-CNN 多尺度特征融合 损失函数 非极大值抑制
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考虑颗粒动态尺度影响的固液相间阻力修正模型研究
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作者 张自超 张利红 李延频 《农业机械学报》 北大核心 2026年第1期262-272,共11页
阻力模型是影响悬移质固液两相流固相浓度分布计算结果的重要因素,现有的相间阻力模型未考虑颗粒动态尺度引起的周围流体湍流强度改变对颗粒运动和扩散的影响,导致固相浓度计算结果与试验值相比仍有误差。为此,针对悬移质固液两相流,采... 阻力模型是影响悬移质固液两相流固相浓度分布计算结果的重要因素,现有的相间阻力模型未考虑颗粒动态尺度引起的周围流体湍流强度改变对颗粒运动和扩散的影响,导致固相浓度计算结果与试验值相比仍有误差。为此,针对悬移质固液两相流,采用流体湍流强度变化率与颗粒动态尺度的表达式,对MTE-Wen-Yu模型进行修正得到改进的PDS-MTE-Wen-Yu模型。通过圆管内固液两相流数值计算对改进模型进行了验证。结果表明,在不同进口流速、不同进口固相浓度和不同固相颗粒粒径时,相比于Wen-Yu模型和MTE-Wen-Yu模型,PDS-MTE-Wen-Yu模型计算得到的固相浓度分布与试验值更加吻合,计算精度更高。在湍流核心区,PDS-MTE-Wen-Yu模型和MTE-Wen-Yu模型的计算精度基本相同;但在近壁区内,PDS-MTE-Wen-Yu模型具有更高的计算精度。但是,随着颗粒粒径和固相浓度的增大,由于大粒径颗粒的惯性增大,湍流改变对颗粒的影响随之降低,PDS-MTE-Wen-Yu模型的计算误差逐渐增大。在固液两相流压力场计算时,MTE-Wen-Yu模型和PDS-MTE-Wen-Yu模型计算得到的压力降基本相同,都更接近试验值,但仍存在一定的误差。因此,PDS-MTE-Wen-Yu模型具有较高的计算精度,更适用于固相颗粒粒径较小的低浓度悬移质固液两相流固相浓度和小流速、低浓度固液两相流压力场的计算。 展开更多
关键词 固液两相流 悬移质 阻力修正模型 颗粒动态尺度 湍流修正函数
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改进YOLOv11s的无人机图像小目标检测模型
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作者 牟毅 黄海松 +3 位作者 李宜汀 付盛伟 李科 朱云伟 《电光与控制》 北大核心 2026年第1期51-57,共7页
为解决无人机目标检测中小尺寸、密集目标检测困难及在边缘设备部署困难的问题,提出了小目标检测模型Drone-YOLO。首先,提出了MF-FPN网络,在降低模型复杂度的同时融合高级语义与低级几何特征;其次,为解决小目标、密集目标难以检测问题... 为解决无人机目标检测中小尺寸、密集目标检测困难及在边缘设备部署困难的问题,提出了小目标检测模型Drone-YOLO。首先,提出了MF-FPN网络,在降低模型复杂度的同时融合高级语义与低级几何特征;其次,为解决小目标、密集目标难以检测问题提出了小目标检测头;而后,提出轻量化检测头LSCD,通过共享卷积降低模型复杂度,并利用组归一化提升检测性能;最后,引入Inner-WIoU损失函数,动态调整锚框权重,使模型更专注于中等质量锚框优化,从而提升回归效率与泛化能力。在公开数据集VisDrone2019上进行实验,改进后模型的mAP 0.5达到44.3%,较YOLOv11s提升6.4个百分点,参数量减少67.5%。 展开更多
关键词 无人机 小目标检测 YOLOv11s 多尺度特征融合 轻量化 损失函数
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Laguerre Series Expansion for Scale Functions and Its Applications in Risk Theory
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作者 Jia-yi XIE Zhen-yu CUI Zhi-min ZHANG 《Acta Mathematicae Applicatae Sinica》 2026年第1期146-162,共17页
We propose an exact explicit closed-form Laguerre series expansion formula to compute the q-scale function of a spectrally negative Lévy process(SNLP),and other functions associated to the scale function for the ... We propose an exact explicit closed-form Laguerre series expansion formula to compute the q-scale function of a spectrally negative Lévy process(SNLP),and other functions associated to the scale function for the first time.The proposed closed-form formula for the scale function has many applications in applied probability and in particular in the Lévy insurance risk theory.We shall show that the new series expansion formulas can be used to express the expected discounted penalty functions,the moments of the present value of total dividend payments as well as the time value of Parisian ruin in the Lévy risk models. 展开更多
关键词 Laguerre series scale function spectrally negative Lévy process ruin probability
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基于二维材料的集成与应用
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作者 杨高琛 马辰龙 +11 位作者 徐浪浪 史文昊 黄鑫宇 孙铭君 毕铭 何啸 孟潇涵 吕晟杰 林维佳 贺敏 童磊 叶镭 《物理学报》 北大核心 2026年第1期45-74,共30页
在后摩尔时代,随着器件物理尺寸的缩放极限和冯·诺依曼架构的局限性逐渐显现,传统硅基集成电路领域面临严峻挑战.然而,二维层状材料凭借无悬挂键、高载流子迁移率、高光生载流子浓度等独特的物理特性,有望突破这些瓶颈.目前,许多... 在后摩尔时代,随着器件物理尺寸的缩放极限和冯·诺依曼架构的局限性逐渐显现,传统硅基集成电路领域面临严峻挑战.然而,二维层状材料凭借无悬挂键、高载流子迁移率、高光生载流子浓度等独特的物理特性,有望突破这些瓶颈.目前,许多二维材料已经实现了规模化生长与应用,在高性能单一功能器件、多功能融合器件、逻辑电路和集成芯片制造与应用当中展现出巨大的潜力.本文综述了二维材料的基本特性、构成的基础功能器件、功能电路模块以及三维集成等方面的研究进展,重点探讨了二维材料在规模化集成方案方面的挑战和解决路径,并为未来的发展方向提出了展望. 展开更多
关键词 二维材料 基础功能器件 逻辑电路 规模化集成
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基于加权Ripley's K-function的多尺度景观格局分析——以江苏盐城滨海湿地为例 被引量:13
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作者 张东菊 左平 邹欣庆 《生态学报》 CAS CSCD 北大核心 2015年第8期2703-2711,共9页
以1987,1992,1997,2002,2007年的遥感影像为例,首次尝试使用加权Ripley's K-function的多尺度格局分析方法,计算了20年来景观异质性在江苏盐城滨海湿地的时间变化和空间分布趋势。通过对研究区的样带划分以及景观类型的点状化处理,... 以1987,1992,1997,2002,2007年的遥感影像为例,首次尝试使用加权Ripley's K-function的多尺度格局分析方法,计算了20年来景观异质性在江苏盐城滨海湿地的时间变化和空间分布趋势。通过对研究区的样带划分以及景观类型的点状化处理,建立滨海湿地样带图层和1987—2007年间各类型景观的点格局数据库,从而分析滨海湿地不同类型景观的空间聚集特征变化。基于加权Ripley's K-function的计算表明,在各级空间尺度和时间变化上,各类型湿地的斑块都呈现出空间聚集分布状态,且1987年以来,不同湿地类型的聚集空间特征尺度和空间分布强度均出现了大幅的增减变化,除互花米草滩之外的自然湿地的聚集空间特征尺度和强度都有明显下降甚至少到无法被检测到,而人工湿地却呈现聚集特征尺度和强度的双增长,且该聚集程度有逐渐增强的趋势。分析表明,既考虑样点的空间位置信息又考虑样点分布范围的加权Ripley's K-function方法能很好地表征湿地景观在多尺度上的变异,且与传统空间景观指数等分析方法的结论在一定程度上保持一致。 展开更多
关键词 盐城滨海湿地 景观空间格局 多尺度空间聚集分析 加权Ripley’s K-function 空间特征尺度 空间分布强度
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