期刊文献+
共找到551篇文章
< 1 2 28 >
每页显示 20 50 100
Local Rate of Convergence in the Functional Limit Theorem for Increments of a Fractional Brownian Motion 被引量:1
1
作者 LIU Yonghong DING Ding ZHOU Xia 《数学进展》 北大核心 2025年第1期197-211,共15页
In this paper,we present local functional law of the iterated logarithm for Cs?rg?-Révész type increments of fractional Brownian motion.The results obtained extend works of Gantert[Ann.Probab.,1993,21(2):104... In this paper,we present local functional law of the iterated logarithm for Cs?rg?-Révész type increments of fractional Brownian motion.The results obtained extend works of Gantert[Ann.Probab.,1993,21(2):1045-1049]and Monrad and Rootzén[Probab.Theory Related Fields,1995,101(2):173-192]. 展开更多
关键词 fractional Brownian motion INCREMENT local functional law of the iterated logarithm large deviation small deviation
原文传递
Existence of a Sigh-Changing Solution Result for Logarithmic Schrödinger Equations with Weight Function
2
作者 Jingxing Huang Junhui Xie 《Journal of Applied Mathematics and Physics》 2024年第7期2665-2681,共17页
This paper is devoted to studying the existence of solutions for the following logarithmic Schrödinger problem: −div(a(x)∇u)+V(x)u=ulogu2+k(x)| u |q1−2u+h(x)| u |q2−2u,  x∈ℝN.(1)We first prove that the correspon... This paper is devoted to studying the existence of solutions for the following logarithmic Schrödinger problem: −div(a(x)∇u)+V(x)u=ulogu2+k(x)| u |q1−2u+h(x)| u |q2−2u,  x∈ℝN.(1)We first prove that the corresponding functional I belongs to C1(HV1(ℝN),ℝ). Furthermore, by using the variational method, we prove the existence of a sigh-changing solution to problem (1). 展开更多
关键词 logarithmic Schrödinger Equations Weight function Constrained Minimization Method Symmetric Mountain Pass Theorem
在线阅读 下载PDF
Adaptive Learning Rate Optimization BP Algorithm with Logarithmic Objective Function
3
作者 李春雨 盛昭瀚 《Journal of Southeast University(English Edition)》 EI CAS 1997年第1期47-51,共5页
This paper presents an improved BP algorithm. The approach can reduce the amount of computation by using the logarithmic objective function. The learning rate μ(k) per iteration is determined by dynamic o... This paper presents an improved BP algorithm. The approach can reduce the amount of computation by using the logarithmic objective function. The learning rate μ(k) per iteration is determined by dynamic optimization method to accelerate the convergence rate. Since the determination of the learning rate in the proposed BP algorithm only uses the obtained first order derivatives in standard BP algorithm(SBP), the scale of computational and storage burden is like that of SBP algorithm,and the convergence rate is remarkably accelerated. Computer simulations demonstrate the effectiveness of the proposed algorithm 展开更多
关键词 BP ALGORITHM ADAPTIVE LEARNING RATE optimization fault diagnosis logarithmic objective function
在线阅读 下载PDF
Logarithm of a Function, a Well-Posed Inverse Problem
4
作者 Silvia Reyes Mora Víctor A. Cruz Barriguete Denisse Guzmán Aguilar 《American Journal of Computational Mathematics》 2014年第1期1-5,共5页
It poses the inverse problem that consists in finding the logarithm of a function. It shows that when the function is holomorphic in a simply connected domain , the solution at the inverse problem exists and is unique... It poses the inverse problem that consists in finding the logarithm of a function. It shows that when the function is holomorphic in a simply connected domain , the solution at the inverse problem exists and is unique if a branch of the logarithm is fixed. In addition, it’s demonstrated that when the function is continuous in a domain , where is Hausdorff space and connected by paths. The solution of the problem exists and is unique if a branch of the logarithm is fixed and is stable;for what in this case, the inverse problem turns out to be well-posed. 展开更多
关键词 logarithm function INVERSE PROBLEM STABILITY
在线阅读 下载PDF
On a special type of Ma-Minda function
5
作者 S.Sivaprasad Kumar Shagun Banga 《Applied Mathematics(A Journal of Chinese Universities)》 SCIE CSCD 2024年第4期654-673,共20页
We introduce a primitive class of analytic functions, by specializing in many wellknown classes, classify Ma-Minda functions based on its conditions and their interesting geometrical aspects. Further, study a newly de... We introduce a primitive class of analytic functions, by specializing in many wellknown classes, classify Ma-Minda functions based on its conditions and their interesting geometrical aspects. Further, study a newly defined subclass of starlike functions involving a special type of Ma-Minda function introduced here for obtaining inclusion and radius results. We also establish some majorization, Bloch function norms, and other related problems for the same class. 展开更多
关键词 Ma-Minda function typically real function Hankel determinants sharp coefficient bounds radius problems logarithmic function
在线阅读 下载PDF
Constructing Hash Function Based on Coupled Network Generated by Logarithmic Map
6
作者 SONG Yu-rong JIANG Guo-ping 《南京邮电大学学报(自然科学版)》 2010年第1期6-10,共5页
In this paper,based on coupled network generated by chaotic logarithmic map,a novel algorithm for constructing hash functions is proposed,which can transform messages and can establish a mapping from the transformed m... In this paper,based on coupled network generated by chaotic logarithmic map,a novel algorithm for constructing hash functions is proposed,which can transform messages and can establish a mapping from the transformed messages to the coupled matrix of the network.The network model is carefully designed to ensure the network dynamics to be chaotic.Through the chaotic iterations of the network,quantization and exclusive-or (XOR) operations,the algorithm can construct hash value with arbitrary length.It is shown by simulations that the algorithm is extremely sensitive to the initial values and the coupled matrix of the network,and has excellent performance in one-way,confusion and diffusion,and collision resistance. 展开更多
关键词 计算机网络 应用程序 网络安全 网络协议
在线阅读 下载PDF
A LAW OF THE ITERATED LOGARITHM FOR NEAREST NEIGHBOR ESTIMATION OF MULTIVARIATE DENSITY FUNCTION
7
作者 洪圣岩 陈规景 +1 位作者 孔繁超 高集体 《Acta Mathematica Scientia》 SCIE CSCD 1992年第4期472-478,共7页
Let X be a d-dimensional random vector with unknown density function f(z) = f (z1, ..., z(d)), and let f(n) be teh nearest neighbor estimator of f proposed by Loftsgaarden and Quesenberry (1965). In this paper, we est... Let X be a d-dimensional random vector with unknown density function f(z) = f (z1, ..., z(d)), and let f(n) be teh nearest neighbor estimator of f proposed by Loftsgaarden and Quesenberry (1965). In this paper, we established the law of the iterated logarithm of f(n) for general case of d greater-than-or-equal-to 1, which gives the exact pointwise strong convergence rate of f(n). 展开更多
关键词 A LAW OF THE ITERATED logarithm FOR NEAREST NEIGHBOR ESTIMATION OF MULTIVARIATE DENSITY function exp
在线阅读 下载PDF
基于水活度法测定包衣种子含水量
8
作者 潘佳 刘亚洁 胡小文 《中国草地学报》 北大核心 2025年第8期142-148,共7页
种子含水量是种子质量评定的重要指标,其准确、快速地测定对种子质量定级尤为重要。为提高种子质量,种子包衣技术在种子生产和贸易中已较为常见。因外围包衣材料的影响,传统的高(低)恒温烘干法无法准确测定种子含水量,往往严重低估包衣... 种子含水量是种子质量评定的重要指标,其准确、快速地测定对种子质量定级尤为重要。为提高种子质量,种子包衣技术在种子生产和贸易中已较为常见。因外围包衣材料的影响,传统的高(低)恒温烘干法无法准确测定种子含水量,往往严重低估包衣种子的实际含水量。鉴于此,本研究以紫花苜蓿、披碱草、多年生黑麦草、鸭茅等4个物种的包衣种子为试验材料,分析包衣种子水活度和裸种子含水量之间的关系,构建基于水活度的包衣种子含水量预测模型。结果表明紫花苜蓿、披碱草、多年生黑麦草、鸭茅4个物种预测模型的拟合优度分别为0.9003、0.9124、0.9076、0.9323,水分预测相对误差分别为2.87%、4.08%、3.07%、4.14%,表明种子水活度可用于包衣种子含水量的无损快速测定。 展开更多
关键词 数学模型 水活度 指数函数 裸种子 决定系数 拟合优度
在线阅读 下载PDF
Logarithmic Sine and Cosine Transforms and Their Applications to Boundary-Value Problems Connected with Sectionally-Harmonic Functions
9
作者 Mithat Idemen 《Applied Mathematics》 2013年第2期378-386,共9页
Let stand for the polar coordinates in R2, ?be a given constant while satisfies the Laplace equation in the wedge-shaped domain or . Here αj(j = 1,2,...,n + 1) denote certain angles such that αj αj(j = 1,2,...,n + ... Let stand for the polar coordinates in R2, ?be a given constant while satisfies the Laplace equation in the wedge-shaped domain or . Here αj(j = 1,2,...,n + 1) denote certain angles such that αj αj(j = 1,2,...,n + 1). It is known that if r = a satisfies homogeneous boundary conditions on all boundary lines ?in addition to non-homogeneous ones on the circular boundary , then an explicit expression of in terms of eigen-functions can be found through the classical method of separation of variables. But when the boundary?condition given on the circular boundary r = a is homogeneous, it is not possible to define a discrete set of eigen-functions. In this paper one shows that if the homogeneous condition in question is of the Dirichlet (or Neumann) type, then the logarithmic sine transform (or logarithmic cosine transform) defined by (or ) may be effective in solving the problem. The inverses of these transformations are expressed through the same kernels on or . Some properties of these transforms are also given in four theorems. An illustrative example, connected with the heat transfer in a two-part wedge domain, shows their effectiveness in getting exact solution. In the example in question the lateral boundaries are assumed to be non-conducting, which are expressed through Neumann type boundary conditions. The application of the method gives also the necessary condition for the solvability of the problem (the already known existence condition!). This kind of problems arise in various domain of applications such as electrostatics, magneto-statics, hydrostatics, heat transfer, mass transfer, acoustics, elasticity, etc. 展开更多
关键词 INTEGRAL Transforms Harmonic functions WEDGE PROBLEMS Boundary-Value PROBLEMS logarithmic SINE TRANSFORM logarithmic COSINE TRANSFORM
在线阅读 下载PDF
面向向量部件的指数和对数函数优化方法
10
作者 沈洁 龙标 +2 位作者 黄春 唐滔 彭林 《计算机工程与科学》 北大核心 2025年第1期18-26,共9页
指数和对数函数是浮点计算中重要的超越函数,在不同应用领域使用广泛。现代处理器向量寄存器宽度呈现逐代增加的趋势,为了进一步提高上层应用对向量部件的利用率,研究向量指数和对数函数优化方法具有重要的科学价值和现实意义。针对现... 指数和对数函数是浮点计算中重要的超越函数,在不同应用领域使用广泛。现代处理器向量寄存器宽度呈现逐代增加的趋势,为了进一步提高上层应用对向量部件的利用率,研究向量指数和对数函数优化方法具有重要的科学价值和现实意义。针对现有向量函数实现的性能瓶颈,设计和实现了面向向量部件的指数和对数函数优化方法,包括基于硬件加速指令的向量查表优化、分支优化和精度性能取舍优化。模拟器上的实验表明,优化实现的向量指数和对数函数均达到业界高精度标准,函数性能优于当前最佳开源实现,加速比达1.44以上。真实应用测试进一步表明,应用程序在优化的向量函数支持下可以实现高效向量化,相比原始标量实现平均性能提升达2.53倍。 展开更多
关键词 指数函数 对数函数 向量化 查表优化 硬件加速指令
在线阅读 下载PDF
中国天然气需求趋势预测分析 被引量:1
11
作者 李洪兵 刘琴 +2 位作者 陈宇光 韩咪 吴小东 《天然气技术与经济》 2025年第3期1-9,82,共10页
为了精准预测天然气需求量演变趋势,采用灰色相对关联度评估并诊断各影响因素间多重共线性的显著水平,遵循关联性强弱递减的准则,采用逐步回归分析法对影响天然气需求的因素进行精细化分析,构建了“最佳”天然气需求预测模型。研究结果... 为了精准预测天然气需求量演变趋势,采用灰色相对关联度评估并诊断各影响因素间多重共线性的显著水平,遵循关联性强弱递减的准则,采用逐步回归分析法对影响天然气需求的因素进行精细化分析,构建了“最佳”天然气需求预测模型。研究结果表明:(1)经济发展是推动中国天然气需求激增最主要的有效动因,能源消费结构优化是促进中国天然气需求增长的关键有效动因;(2)所构建的“最佳”逐步回归双对数天然气需求量函数模型,能精准捕捉天然气需求非线性拐点变化趋势,表现出优良的预测性能,该模型可作为分析天然气需求变化趋势的有力预测工具;(3)中国天然气需求量将于2035—2036年达到峰值,届时天然气需求峰值约为5938×10^(8) m^(3),到2040年中国天然气需求量将为4784×10^(8) m^(3),年均增长率降至1.8%。结论认为,所提出的“最佳”逐步回归双对数需求函数预测方法的使用不局限于天然气需求量预测,既能为中国天然气需求变化趋势预测给予技术支持,又能为能源相关的企事业单位开展天然气资源配置计划和政策制定提供理论依据。 展开更多
关键词 天然气需求 预测模型 双对数需求函数 灰色关联分析 逐步回归分析 峰值预测
在线阅读 下载PDF
一类单叶函数对数系数的三阶Hankel行列式
12
作者 郭栋 李宗涛 +1 位作者 傅秀莲 王庆 《曲阜师范大学学报(自然科学版)》 2025年第4期73-80,共8页
令H表示单位圆盘D={z∈ℂ:|z|<1}内具有下述形式的解析函数类f(z)=z+Σ_(n=2)^(∞)a_(n)z^(n).该文研究了单位圆盘D上的解析函数类ST(i):ST(i)={f:Re{(1-z^(2))f(z)/z}>0,f∈H,z∈D}的Zalcman泛函J_(2,4)(f)、J_(3,3)(f)、J_(3,4)... 令H表示单位圆盘D={z∈ℂ:|z|<1}内具有下述形式的解析函数类f(z)=z+Σ_(n=2)^(∞)a_(n)z^(n).该文研究了单位圆盘D上的解析函数类ST(i):ST(i)={f:Re{(1-z^(2))f(z)/z}>0,f∈H,z∈D}的Zalcman泛函J_(2,4)(f)、J_(3,3)(f)、J_(3,4)(f)和对数系数的Hankel行列式.部分上界是紧界. 展开更多
关键词 单叶函数 Hankel行列式 对数系数 Zalcman泛函
在线阅读 下载PDF
s-对数凸函数的一些性质及其应用
13
作者 何晶晶 江慎铭 《南昌航空大学学报(自然科学版)》 2025年第1期60-65,共6页
首先,给出了-对数凸(凹)s函数的性质和判定定理;其次,给出了一些新型的积分不等式并且加以证明;最后,给s出了-对数凸(凹)函数在实际计算中的一些运用。
关键词 s-对数凸(凹)函数 性质 判定定理 积分不等式
在线阅读 下载PDF
与对数导数相关的正规定则
14
作者 古丽米热·吐尔逊 杨锦华 《龙岩学院学报》 2025年第2期9-13,37,共6页
利用Zalcman-Pang引理,结合对数导数函数族正规,对满足条件f′(z)-a(z)f^(k)(z)≠b(z)亚纯函数族的正规性进行研究,得到当k=3且例外函数a(z),b(z)均为全纯函数时,亚纯函数族是正规的。
关键词 亚纯函数 正规定则 对数导数
在线阅读 下载PDF
An NOMA-VLC power allocation scheme for multi-user based on sparrow search algorithm
15
作者 WANG Xing WANG Haitao +3 位作者 DONG Zhenliang XIONG Yingfei SHI Huili WANG Ping 《Optoelectronics Letters》 2025年第5期278-283,共6页
A non-orthogonal multiple access(NOMA) power allocation scheme on the basis of the sparrow search algorithm(SSA) is proposed in this work. Specifically, the logarithmic utility function is utilized to address the pote... A non-orthogonal multiple access(NOMA) power allocation scheme on the basis of the sparrow search algorithm(SSA) is proposed in this work. Specifically, the logarithmic utility function is utilized to address the potential fairness issue that may arise from the maximum sum-rate based objective function and the optical power constraints are set considering the non-negativity of the transmit signal, the requirement of the human eyes safety and all users' quality of service(Qo S). Then, the SSA is utilized to solve this optimization problem. Moreover, to demonstrate the superiority of the proposed strategy, it is compared with the fixed power allocation(FPA) and the gain ratio power allocation(GRPA) schemes. Results show that regardless of the number of users considered, the sum-rate achieved by SSA consistently outperforms that of FPA and GRPA schemes. Specifically, compared to FPA and GRPA schemes, the sum-rate obtained by SSA is increased by 40.45% and 53.44% when the number of users is 7, respectively. The proposed SSA also has better performance in terms of user fairness. This work will benefit the design and development of the NOMA-visible light communication(VLC) systems. 展开更多
关键词 NOMA logarithmic utility function VLC Sparrow Search Algorithm sparrow search algorithm ssa fairness issue power allocation Sum Rate
原文传递
自然对数函数在求极限问题中的应用
16
作者 薛维顺 赵焕青 《高师理科学刊》 2025年第6期14-17,21,共5页
讨论一类自然对数函数比的极限问题,给出相应的求解方法。利用自然对数函数的性质和无穷小的比较,求解不可导函数的极限问题。拓宽了解题思路,丰富了求解方法。
关键词 自然对数函数 极限 无穷小
在线阅读 下载PDF
复杂光环境下的车牌图像定位算法研究
17
作者 刘璐 《西安交通工程学院学术研究》 2025年第1期73-76,共4页
汽车保有量持续增长促使交通管理在全球经济蓬勃发展的大背景下要求更高,需要更精准的车牌识别技术,但目前的车牌定位技术面临着诸多挑战尤其是在光照条件多变、背景环境复杂、车牌老化褪色、表面瑕疵等不利因素下,其定位精确度和效率... 汽车保有量持续增长促使交通管理在全球经济蓬勃发展的大背景下要求更高,需要更精准的车牌识别技术,但目前的车牌定位技术面临着诸多挑战尤其是在光照条件多变、背景环境复杂、车牌老化褪色、表面瑕疵等不利因素下,其定位精确度和效率受到了一定的限制,这是目前车牌定位技术所面临的诸多挑战。针对上述问题,通过引入分段对数变换技术,对中间亮度区域进行优化再降低整体亮度范围,通过精细化调控有效增强低光环境下的画面亮度,为车牌区域的初步识别打下坚实基础。此外为应对日间强光导致图像曝光过多的问题进一步整合自适应分段双边伽马变换增强算法,使高亮图像的视觉效果因其非线性对比度调节能力得到显著提升,车牌细节也更加清晰可辨。本文旨在通过整合上述先进的图像处理技术在一定程度上规避算法层面的亢余性,同时构建出一种更高效的车牌定位解决方案以应对现实世界中复杂多变的识别挑战。 展开更多
关键词 车牌识别 图像处理 对数变换函数
在线阅读 下载PDF
基于对数处理机制和时频掩蔽估计的语音增强
18
作者 王显云 窦姗姗 程楚皓 《电子科技》 2025年第1期45-51,72,共8页
针对时频谱模型估计语音不准确的问题,文中提出采用模型变换的方式来获得噪声和语音的对数概率密度函数,同时借助带噪语音、干净语音和噪声之间的对数关系并结合最小均方误差(Minimum Mean Square Error,MMSE)估计理论推导出估计语音对... 针对时频谱模型估计语音不准确的问题,文中提出采用模型变换的方式来获得噪声和语音的对数概率密度函数,同时借助带噪语音、干净语音和噪声之间的对数关系并结合最小均方误差(Minimum Mean Square Error,MMSE)估计理论推导出估计语音对数谱的时频掩模。基于语音和噪声的对数概率分布推导出了一种软掩模,该软掩模可对带噪语音的对数子带进行加权以降低噪声,提高语音估计的准确性。仿真结果表明,与未处理的含噪语音相比,所提方法在噪声抑制方面具有3 dB以上的提升,基于最小均方误差的时频掩模和软掩模在听觉感知方面的平均提升量分别为27.7%和29.4%,在可懂度方面的平均提升量分别为12.7%和14.3%。 展开更多
关键词 语音处理 语音增强 对数概率密度函数 时频掩模 噪声抑制 非监督学习 软掩蔽 对数谱
在线阅读 下载PDF
混合Pareto-logarithmic分布
19
作者 田兵 《常熟理工学院学报》 2021年第2期115-119,共5页
基于元件的寿命服从双参数的混合Pareto分布,而元件的个数服从Logarithmic分布.本文提出了一种新的寿命分布:混合Pareto-logarithmic分布(MPL分布),研究了MPL分布的各种性质,同时给出了其参数的极大似然估计的渐近协方差阵和近似置信区间.
关键词 PARETO分布 logarithmic分布 失效率函数 生存函数 极大似然估计
在线阅读 下载PDF
Hermite-Hadamard不等式的一类推广
20
作者 包琳娜 王淑红 《内蒙古民族大学学报(自然科学版)》 2025年第1期7-16,共10页
基于Katugampola分数阶积分和对数积分,对Hermite-Hadamard不等式进行了加细和推广。引进了二元函数的Katugampola分数阶积分的定义,并分别利用一元函数的凸性和二元函数的协同凸性,建立了一类Hermite-Hadamard型不等式。当取特殊函数时... 基于Katugampola分数阶积分和对数积分,对Hermite-Hadamard不等式进行了加细和推广。引进了二元函数的Katugampola分数阶积分的定义,并分别利用一元函数的凸性和二元函数的协同凸性,建立了一类Hermite-Hadamard型不等式。当取特殊函数时,分别得到了一元凸函数和二元协同凸函数的Hermite-Hadamard不等式、Hermite-Hadamard型分数阶积分不等式和Hermite-Hadamard型对数积分不等式。 展开更多
关键词 凸函数 协同凸函数 HERMITE-HADAMARD不等式 Katugampola分数阶积分 对数积分
在线阅读 下载PDF
上一页 1 2 28 下一页 到第
使用帮助 返回顶部