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Improving the utility of locally differentially private protocols for longitudinal and multidimensional frequency estimates

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Digital Communications and Networks 2024年第2期10卷 369-379页

作者： Héber H.Arcolezi Jean-François Couchot Bechara Al Bouna Xiaokui Xiao Inria andÉcole Polytechnique(IPP) PalaiseauFrance Femto-ST Institute Univ.Bourg.Franche-ComtéUBFCCNRSBelfortFrance TICKET Lab. Antonine University Hadat-BaabdaBaabdaLebanon School of Computing National University of SingaporeSingaporeSingapore

This paper investigates the problem of collecting multidimensional data throughout time(i.e.,longitudinal studies)for the fundamental task of frequency estimation under Local Differential Privacy(LDP)*** to frequency estimation of a single attribute,the multidimensional aspect demands particular attention to the privacy ***,when collecting user statistics longitudinally,privacy progressively ***,the“multiple”settings in combination(i.e.,many attributes and several collections throughout time)impose several challenges,for which this paper proposes the first solution for frequency estimates under *** tackle these issues,we extend the analysis of three state-of-the-art LDP protocols(Generalized Randomized Response–GRR,Optimized Unary Encoding–OUE,and Symmetric Unary Encoding–SUE)for both longitudinal and multidimensional data *** the known literature uses OUE and SUE for two rounds of sanitization(***),i.e.,L-OUE and L-SUE,respectively,we analytically and experimentally show that starting with OUE and then with SUE provides higher data utility(i.e.,L-OSUE).Also,for attributes with small domain sizes,we propose Longitudinal GRR(L-GRR),which provides higher utility than the other protocols based on unary ***,we also propose a new solution named Adaptive LDP for LOngitudinal and multidimensional FREquency Estimates(ALLOMFREE),which randomly samples a single attribute to be sent with the whole privacy budget and adaptively selects the optimal protocol,i.e.,either L-GRR or *** shown in the results,ALLOMFREE consistently and considerably outperforms the state-of-the-art L-SUE and L-OUE protocols in the quality of the frequency estimates.

关键词： Local differential privacy Discrete distribution estimation Frequency estimation multidimensional data Longitudinal studies

Exploring visual quality of multidimensional time series projections

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Visual Informatics 2024年第2期8卷 27-42页

作者： Tanja Munz-Körner Daniel Weiskopf Visualization Research Center(VISUS) University of StuttgartAllmandring 19StuttgartGermany

Dimensionality reduction is often used to project time series data from multidimensional to two-dimensional space to generate visual representations of the temporal *** this context,we address the problem of multidimensional time series visualization by presenting a new method to show and handle projection errors introduced by dimensionality reduction techniques on multidimensional temporal *** visualization,subsequent time instances are rendered as dots that are connected by lines or curves to indicate the temporal ***,inevitable projection artifacts may lead to poor visualization quality and misinterpretation of the temporal *** projected data points,inaccurate variations in the distances between projected time instances,and intersections of connecting lines could lead to wrong assumptions about the original *** adapt local and global quality metrics to measure the visual quality along the projected time series,and we introduce a model to assess the projection error at intersecting *** serve as a basis for our new uncertainty visualization techniques that use different visual encodings and interactions to indicate,communicate,and work with the visualization uncertainty from projection errors and artifacts along the timeline of data points,their connections,and *** approach is agnostic to the projection method and works for linear and non-linear dimensionality reduction methods alike.

关键词： Time series multidimensional data Dimensionality reduction Projection errors Visual quality Visual analytics

Angle-uniform parallel coordinates

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Computational Visual Media 2023年第3期9卷 495-512页

作者： Kaiyi Zhang Liang Zhou Lu Chen Shitong He Daniel Weiskopf Yunhai Wang School of Computer Science and Technology Shandong UniversityQingdao 266237China National Institute of Health data Science Peking UniversityBeijing 100191China Visualization Research Center(VISUS) University of Stuttgart70569 StuttgartGermany

We present angle-uniform parallel coordinates,a data-independent technique that deforms the image plane of parallel coordinates so that the angles of linear relationships between two variables are linearly mapped along the horizontal axis of the parallel coordinates *** being a common method for visualizing multidimensional data,parallel coordinates are ineffective for revealing positive correlations since the associated parallel coordinates points of such structures may be located at infinity in the image plane and the asymmetric encoding of negative and positive correlations may lead to unreliable *** address this issue,we introduce a transformation that bounds all points horizontally using an angleuniform mapping and shrinks them vertically in a structure-preserving fashion;polygonal lines become smooth curves and a symmetric representation of data correlations is *** further propose a combined subsampling and density visualization approach to reduce visual clutter caused by *** method enables accurate visual pattern interpretation of data correlations,and its data-independent nature makes it applicable to all multidimensional *** usefulness of our method is demonstrated using examples of synthetic and real-world datasets.

关键词： parallel coordinates multidimensional data deformation correlations

LongLine:Visual Analytics System for Large-scale Audit Logs

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Visual Informatics 2018年第1期2卷 82-97页

作者： Seunghoon Yoo Jaemin Jo Bohyoung Kim Jinwook Seo Seoul National University Korea Hankuk University of Foreign Studies Korea

Audit logs are different from other software logs in that they record the most primitive events(i.e.,system calls)in modem operating *** logs contain a detailed trace of an operating system,and thus have received great attention from security experts and system ***,the complexity and size of audit logs,which increase in real time,have hindered analysts from understanding and analyzing *** this paper,we present a novel visual analytics system,LongLine,which enables interactive visual analyses of large-scale audit *** lowers the interpretation barrier of audit logs by employing human-understandable representations(e.g.,file paths and commands)instead of abstract indicators of operating systems(e.g.,file descriptors)as well as revealing the temporal patterns of the logs in a multi-scale fashion with meaningful granularity of time in mind(e.g.,hourly,daily,and weekly).LongLine also streamlines comparative analysis between interesting subsets of logs,which is essential in detecting anomalous behaviors of *** addition,LongLine allows analysts to monitor the system state in a streaming fashion,keeping the latency between log creation and visualization less than one ***,we evaluate our system through a case study and a scenario analysis with security experts.

关键词： Visual Analytics Log Visualization multidimensional data

Dimensionality reduction model based on integer planning for the analysis of key indicators affecting life expectancy

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Journal of data and Information Science 2023年第4期8卷 102-124页

作者： Wei Cui Zhiqiang Xu Ren Mu School of Statistics Jilin University of Finance and EconomicsChangchunJilin 130117China

Purpose:Exploring a dimensionality reduction model that can adeptly eliminate outliers and select the appropriate number of clusters is of profound theoretical and practical ***,the interpretability of these models presents a persistent ***/methodology/approach:This paper proposes two innovative dimensionality reduction models based on integer programming(DRMBIP).These models assess compactness through the correlation of each indicator with its class center,while separation is evaluated by the correlation between different class *** contrast to DRMBIP-p,the DRMBIP-v considers the threshold parameter as a variable aiming to optimally balances both compactness and ***:This study,getting data from the Global Health Observatory(GHO),investigates 141 indicators that influence life *** findings reveal that DRMBIP-p effectively reduces the dimensionality of data,ensuring *** also maintains compatibility with other ***,DRMBIP-v finds the optimal result,showing exceptional *** of the results reveals that all classes have a high *** limitations:The DRMBIP-p requires the input of the correlation threshold parameter,which plays a pivotal role in the effectiveness of the final dimensionality reduction *** the DRMBIP-v,modifying the threshold parameter to variable potentially emphasizes either separation or *** necessitates an artificial adjustment to the overflow component within the objective *** implications:The DRMBIP presented in this paper is adept at uncovering the primary geometric structures within high-dimensional *** by life expectancy data,this paper demonstrates potential to assist data miners with the reduction of data ***/value:To our knowledge,this is the first time that integer programming has been used to build a dimensionality reduction model with indicator filt

关键词： Integer programming multidimensional data Dimensionality reduction Life expectancy