检索结果-内蒙古大学图书馆

Efficient approximation of branching random walk Gibbs measures

ELECTRONIC JOURNAL OF PROBABILITY 2022年第none期27卷 1-18页

作者： Ho, Fu-Hsuan Maillard, Pascal CNRS Inst Math Toulouse UMR5219 Toulouse France Univ Toulouse 3 Paul Sabatier Inst Math Toulouse 118 Route Narbonne F-31062 Toulouse 9 France

Disordered systems such as spin glasses have been used extensively as models for high-dimensional random landscapes and studied from the perspective of optimization algorithms. In a recent paper by L. Addario-Berry and the second author, the continuous random energy model (CREM) was proposed as a simple toy model to study the efficiency of such algorithms. The following question was raised in that paper: what is the threshold ??G, at which sampling (approximately) from the Gibbs measure at inverse temperature ?? becomes algorithmically hard? This paper is a first step towards answering this question. We consider the branching random walk, a time-homogeneous version of the continuous random energy model. We show that a simple greedy search on a renormalized tree yields a linear-time algorithm which approximately samples from the Gibbs measure, for every ?? ??c, the (static) critical point. More precisely, we show that for every ?? 0, there exists such an algorithm such that the specific relative entropy between the law sampled by the algorithm and the Gibbs measure of inverse temperature ?? is less than ?? with high probability. In the supercritical regime ?? > ??c, we provide the following hardness result. Under a mild regularity condition, for every ?? > 0, there exists z > 0 such that the running time of any given algorithm approximating the Gibbs measure stochastically dominates a geometric random variable with parameter e???z N on an event with probability at least 1 ??? ??.

关键词： algorithmic hardness branching random walk Gibbs measure Kullback-Leibler divergence sampling algorithm

来源：评论

学校读者我要写书评

暂无评论

Intelligent sampling of high-dimensional joint mobility space for analysis of articular function

引用

METHODS IN ECOLOGY AND EVOLUTION 2023年第2期14卷 569-582页

作者： Bishop, Peter J. Brocklehurst, Robert J. Pierce, Stephanie E. Harvard Univ Museum Comparat Zool Cambridge MA 02138 USA Harvard Univ Dept Organism & Evolutionary Biol Cambridge MA 02138 USA Queensland Museum Geosci Program Brisbane Qld Australia

Studies of joint structure and function have played a central role in understanding palaeobiology and major functional transitions in evolutionary history, where fossilized hard parts (e.g. bones) are often all that remain. Current digital methods for quantifying articular function depend on exhaustively sampling all possible joint poses, but this is computationally intensive, becoming prohibitively so with more degrees of freedom. This has impeded more sophisticated analyses or broader application of these methods to more diverse questions and species. The present study introduces 'APSE' (Accelerated Pose Searching with Electrostatics), an iterative algorithm for rapidly and intelligently sampling high-dimensional joint pose space to quantify articular function and mobility. Key features of the algorithm are: known viable joint poses inform the search for new poses in successive generations;the search preferentially targets under-explored regions of pose space, while avoiding over-explored regions;large swaths of inviable pose space are never evaluated, thus minimizing wasted time;and parallelizability. The efficacy of the algorithm was benchmarked with diverse theoretical and biological joints. As a case study to demonstrate its utility, APSE was used to investigate mobility in the enigmatic shoulder joint of the extinct 'pelycosaur'-grade synapsid Dimetrodon, the function of which has been widely debated. APSE produces high-dimensional joint mobility assessments with greater precision than state-of-the-art exhaustive sampling methods. More viable poses are identified at a greater sampling density, but in a fraction of the time taken by current methods (hours, not days or weeks). Results for Dimetrodon shoulder mobility indicate strong coupling between most degrees of freedom across the joint's full range of motion, a stark contrast to the flexible shoulder of most extant tetrapods. APSE provides a time-efficient means to quantitatively measure articular function

关键词： articular function Dimetrodon evolutionary biomechanics joint mobility range of motion sampling algorithm

来源：评论

学校读者我要写书评

暂无评论

ONBRA: Rigorous Estimation of the Temporal Betweenness Centrality in Temporal Networks 22

ONBRA: Rigorous Estimation of the Temporal Betweenness Centr...

引用

31st ACM Web Conference (WWW)

作者： Santoro, Diego Sarpe, Ilie Univ Padua Dept Informat Engn Padua Italy

ISBN: (纸本)9781450390965

In network analysis, the betweenness centrality of a node informally captures the fraction of shortest paths visiting that node. The computation of the betweenness centrality measure is a fundamental task in the analysis of modern networks, enabling the identification of the most central nodes in such networks. Additionally to being massive, modern networks also contain information about the time at which their events occur. Such networks are often called temporal networks. The temporal information makes the study of the betweenness centrality in temporal networks (i.e., temporal betweenness centrality) much more challenging than in static networks (i.e., networks without temporal information). Moreover, the exact computation of the temporal betweenness centrality is often impractical on even moderately-sized networks, given its extremely high computational cost. A natural approach to reduce such computational cost is to obtain high-quality estimates of the exact values of the temporal betweenness centrality. In this work we present ONBRA, the first sampling-based approximation algorithm for estimating the temporal betweenness centrality values of the nodes in a temporal network, providing rigorous probabilistic guarantees on the quality of its output. ONBRA is able to compute the estimates of the temporal betweenness centrality values under two different optimality criteria for the shortest paths of the temporal network. In addition, ONBRA outputs high-quality estimates with sharp theoretical guarantees leveraging on the empirical Bernstein bound, an advanced concentration inequality. Finally, our experimental evaluation shows that ONBRA significantly reduces the computational resources required by the exact computation of the temporal betweenness centrality on several real world networks, while reporting high-quality estimates with rigorous guarantees.

关键词： Temporal networks Temporal betweenness centrality sampling algorithm Probabilistic analysis

来源：评论

学校读者我要写书评

暂无评论

UUD-Fusion: An unsupervised universal image fusion approach via generative diffusion model

引用

COMPUTER VISION AND IMAGE UNDERSTANDING 2024年 249卷

作者： Wang, Xiangxiang Fang, Lixing Zhao, Junli Pan, Zhenkuan Li, Hui Li, Yi Qingdao Univ Coll Comp Sci & Technol Qingdao 266071 Peoples R China Jiangnan Univ Sch Artificial Intelligence & Comp Sci Wuxi 214122 Peoples R China

Image fusion is a classical problem in the field of image processing whose solutions are usually not unique. The common image fusion methods can only generate a fixed fusion result based on the source image pairs. They tend to be applicable only to a specific task and have high computational costs. Hence, in this paper, a two-stage unsupervised universal image fusion with generative diffusion model is proposed, termed as UUDFusion. For the first stage, a strategy based on the initial fusion results is devised to offload the computational effort. For the second stage, two novel sampling algorithms based on generative diffusion model are designed. The fusion sequence generation algorithm (FSGA) searches fora series of solutions in the solution space by iterative sampling. The fusion image enhancement algorithm (FIEA) greatly improves the quality of the fused images. Qualitative and quantitative evaluations of multiple datasets with different modalities demonstrate the great versatility and effectiveness of UUD-Fusion. It is capable of solving different fusion problems, including multi-focus image fusion task, multi-exposure image fusion task, infrared and visible fusion task, and medical image fusion task. The proposed approach is superior to current state-of-the-art methods. Our code is publicly available at https://***/xiangxiang-wang/UUD-Fusion.

关键词： Unsupervised Universal Image fusion Diffusion sampling algorithm

来源：评论

学校读者我要写书评

暂无评论

User-Driven Adaptive sampling for Massive Internet of Things

引用

IEEE ACCESS 2020年 8卷 135798-135810页

作者： Kim-Hung, Le Le-Trung, Quan Vietnam Natl Univ Ho Chi Minh City Univ Informat Technol Fac Comp Networks & Commun Ho Chi Minh City 700000 Vietnam

Energy conservation techniques are crucial to achieving high reliability in the Internet of Things (IoT) services, especially in the Massive IoT (MIoT), which stringently requires cost-effective and low-energy consumption for battery-powered devices. Most of the proposed techniques generally assume that data acquiring and processing consume significantly lower than that of communication. Unfortunately, this assumption is incorrect in the MIoT scenario, which mostly involves the low-power wide-area network (LPWAN) and complex data sensing operations (e.g., biological and seismic sensing) using "power-hungry" sensors (e.g., gas sensors, seismometers). Thus, sensing actions may consume even more energy than transmission. In addition, none of them support end-users in controlling the trade-off between energy conservation and data precision. To deal with these issues, we propose an adaptive sampling algorithm that estimates the optimal sampling frequencies in real-time for IoT devices based on the changes of collected data. Given a user's saving desire, our algorithm could minimize the device's energy consumption while ensuring the precision of collected information. Practical experiments over IoT datasets have shown that our algorithm can reduce the number of acquired samples up to 20 times compared with a traditional fixed-rate approach at extremely low Normal Mean Error value around 3.45%.

关键词： Internet of Things Gas detectors Energy consumption Power demand Real-time systems Batteries Constrained devices energy efficiency massive internet of things sampling algorithm

来源：评论

学校读者我要写书评

暂无评论

Effects of stormwater infrastructure data completeness and model resolution on urban flood modeling

引用

JOURNAL OF HYDROLOGY 2022年 607卷 127498-127498页

作者： Shrestha, Ashish Mascaro, Giuseppe Garcia, Margaret Arizona State Univ Sch Sustainable Engn & Built Environm Tempe AZ 85281 USA

The accuracy of hydrologic and hydrodynamic models, used to study urban hydrology and predict urban flooding, depends on the availability of high-resolution terrain and infrastructure data. Unfortunately, cities often do not have or cannot release complete infrastructure data, and high-resolution terrain data products are not available everywhere. In this study, we quantify how the accuracy and precision of urban hydrologic hydrodynamic models vary as a function of data completeness and model resolution. For this aim, we apply the one-dimensional (1D) and coupled one-and two-dimensional (1D-2D) versions of the U.S. Environmental Protection Agency's Storm Water Management Model (SWMM) in an urban catchment in the city of Phoenix, Arizona. Here, we have collected detailed infrastructure data, a high-resolution 0.3-m LiDAR-based digital elevation model, and catchment properties data. We tested several model configurations assuming different levels of (i) availability of stormwater infrastructure data (ranging from 5% to 75% of attribute-values missing) and (ii) terrain aggregation (i.e., 4.6 m and 9.7 m). These configurations were generated through random Monte Carlo sampling for SWMM 1D and selective sampling with four cases for SWMM 1D-2D. We ran simulations under the 50-year return period design storm and compared simulated flood metrics assuming the highest resolution and complete data model configuration as a reference. The study found that the model may over or underestimate flood volume and duration with different levels of missing data depending on the parameters - roughness, diameter or depth, and that model performance is more sensitive to missing data that is downstream and closer to the outfall as opposed to missing data upstream. Errors in flood depth, area and volume estimation are functions of both the data completeness and model resolution. Missing feature data leads to overestimation of flood depth, while lower model resolution results in underestimati

关键词： Urban flood Urban stormwater Hydrodynamic modeling SWMM Urban infrastructure sampling algorithm

来源：评论

学校读者我要写书评

暂无评论

odeN: Simultaneous Approximation of Multiple Motif Counts in Large Temporal Networks 21

odeN: Simultaneous Approximation of Multiple Motif Counts in...

引用

30th ACM International Conference on Information and Knowledge Management (CIKM)

作者： Sarpe, The Vandin, Fabio Univ Padua Dept Informat Engn Padua Italy

ISBN: (纸本)9781450384469

Counting the number of occurrences of small connected subgraphs, called temporal motifs, has become a fundamental primitive for the analysis of temporal networks, whose edges are annotated with the time of the event they represent. One of the main complications in studying temporal motifs is the large number of motifs that can be built even with a limited number of vertices or edges. As a consequence, since in many applications motifs are employed for exploratory analyses, the user needs to iteratively select and analyze several motifs that represent different aspects of the network, resulting in an inefficient, time-consuming process. This problem is exacerbated in large networks, where the analysis of even a single motif is computationally demanding. As a solution, in this work we propose and study the problem of simultaneously counting the number of occurrences of multiple temporal motifs, all corresponding to the same (static) topology (e.g., a triangle). Given that for large temporal networks computing the exact counts is unfeasible, we propose odeN, a sampling-based algorithm that provides an accurate approximation of all the counts of the motifs. We provide analytical bounds on the number of samples required by odeN to compute rigorous, probabilistic, relative approximations. Our extensive experimental evaluation shows that odeN enables the approximation of the counts of motifs in temporal networks in a fraction of the time needed by state-of-the-art methods, and that it also reports more accurate approximations than such methods.

关键词： temporal motifs sampling algorithm temporal networks randomized algorithm

来源：评论

学校读者我要写书评

暂无评论

A Design Centering Methodology for Probabilistic Design Space 16

A Design Centering Methodology for Probabilistic Design Spac...

引用

16th IFAC Symposium on Advanced Control of Chemical Processes (ADCHEM)

作者： Kusumo, Kennedy P. Morrissey, James Mitchell, Hamish Shah, Nilay Chachuat, Benoit Imperial Coll London Dept Chem Engn Sargent Ctr Proc Syst Engn London England

The use of mathematical models for design space characterization has become commonplace in pharmaceutical quality-by-design, providing a systematic risk-based approach to assurance of quality. This paper presents a methodology to complement sampling algorithms by computing the largest box inscribed within a given probabilistic design space at a desired reliability level. Such an encoding of the samples yields an operational envelope that can be conveniently communicated to process operators as independent ranges in process parameters. The first step involves training a feed-forward multi-layer perceptron as a surrogate of the sampled probability map. This surrogate is then embedded into a design centering problem, formulated as a semi-infinite program and solved using a cutting-plane algorithm. Effectiveness and computational tractability are demonstrated on the case study of a batch reactor with two critical process parameters. Copyright (C) 2021 The Authors.

关键词： quality-by-design probabilistic design space sampling algorithm design centering multi-layer perceptron

来源：评论

学校读者我要写书评

暂无评论

Motion Planning of Planar Closed Chains Based on Structural Sets

引用

IEEE ACCESS 2020年 8卷 117203-117217页

作者： Liu, Guanfeng Trinkle, Jeff Yang, Yong Luo, Shaoming Guangdong Polytech Normal Univ Sch Mechatron Engn Guangzhou 510665 Peoples R China Lehigh Univ Dept Comp Sci Bethlehem PA 18015 USA

This paper investigates the motion planning problem of planar m-link (m >= 4) closed chains among point obstacles with extension to arbitrary convex 2-D obstacles. The configuration space (C-space) of closed chains is embedded into two copies of m-3 dimensional tori. Two structural sets, the C-boundaries and the C-obstacles, are analyzed based upon the C-spaces of recursively constructed lower-dimensional closed chains. They contain essential structural information about the connectivity of the collision-free portion (C-free) of the C-space. By approximating each workspace obstacle by a set of points on the boundary after dilation, its corresponding C-obstacle is guaranteed to be covered by the C-obstacle of the convex hull of the point set. This permits a resolution-complete roadmap algorithm that puts specific bias for sampling the structural sets. Several benchmark examples are presented that compare the performance between our algorithm and the traditional algorithms. Animation videos and source codes are also provided which demonstrate the effectiveness of our method for closed chains of up to 20 links.

关键词： Path planning closed chains boundary variety bifurcation narrow passages sampling algorithm

来源：评论

学校读者我要写书评

暂无评论

Fast One-to-Many Reliability Estimation for Uncertain Graphs 31st

Fast One-to-Many Reliability Estimation for Uncertain Graphs

引用

31st International Conference on Database and Expert Systems Applications (DEXA)

作者： Yanagisawa, Junya Shiokawa, Hiroaki Univ Tsukuba Grad Sch Sci & Technol Tsukuba Ibaraki Japan Univ Tsukuba Ctr Computat Sci Tsukuba Ibaraki Japan

ISBN: (纸本)9783030590031;9783030590024

Uncertain graphs commonly represent noisy and unreliable real-world datasets in various applications. One fundamental primitive on uncertain graphs is reliability, which evaluates the connection robustness between two specific nodes. Although reliability is helpful to analyzeuncertain graphs, it is computationally expensive because (1) the reliability estimation is #P-hard problem and (2) many applications require reliability computations among all possible pairs of nodes. To overcome the aforementioned problems, we present a novel algorithm called Sharing RCSS+, which efficiently computes the reliability among all possible pairs of nodes. Our extensive experiments on both real-world and synthetic uncertain graphs clarified that Sharing RCSS+ achieves a more efficient estimation than the state-of-the-art methods.

关键词： Uncertain graphs Reliability sampling algorithm

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：