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SSRN 2022年

作者： Poureidi, Abolfazl Farshi, Mohammad Department of Mathematical Sciences Shahrood University of Technology Shahrood Iran Combinatorial and Geometric Algorithms Lab. Department of Computer Science Yazd University Yazd Iran

Let t > 1 be a real number. A geometric t-spanner is a geometric graph for a point set in Rd with straight line segments between vertices such that the ratio of the shortest-path distance between every pair of vertices in the graph (with Euclidean edge lengths) to their actual Euclidean distance is at most *** imprecise point set is modeled by a set $R$ of regions in $\mathbb{R}^d$. If one chooses a point inside each region of $R$, then the resulting point set is called a precise instance from~$R$.An imprecise $t$-spanner for an imprecise point set $R$ is a graph $G=(R,E)$ such that for each precise instance $S$ from $R$, graph $G_S=(S,E_S)$, where $E_S$ is the set of edges corresponding to $E$ and $S$, is a $t$-*** this paper, we show an imprecise point set $R$ of $n$ straight-line segments in the plane such that any imprecise $t$-spanner for $R$ has $\Omega(n^2)$ edges. Then, we give an algorithm that computes an imprecise $t$-spanner for a set of $n$ pairwise disjoint $d$-dimensional balls with arbitrary sizes. This imprecise $t$-spanner has $O(n/(t-1)^d)$ edges and can be computed in $O(n\log n/(t-1)^d)$ time. Finally, we show that given an imprecise spanner, finding a precise instance such that its corresponding precise spanner has minimum dilation between all possible precise instances of the imprecise spanner is NP-hard, no matter if crossing edges is allowed or not. © 2022, The Authors. All rights reserved.

关键词： Geometry

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HeartPad: Real-time visual guidance for cardiac ultrasound

HeartPad: Real-time visual guidance for cardiac ultrasound

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Workshop at SIGGRAPH Asia 2012, WASA 2012

作者： Ford, Steven T. Viola, Ivan Bruckner, Stefan Torp, Hans Kiss, Gabriel Norwegian University of Science and Technology MI Lab. Department of Circulation and Medical Imaging Trondheim Norway Høgskolen I Nord-Trøndelag Norway University of Bergen Norway Christian Michelsen Research Norway Institute of Computer Graphics and Algorithms Vienna University of Technology Austria St. Olavs Hospital Trondheim Norway

ISBN: (纸本)9781450318358

Medical ultrasound is a challenging modality when it comes to image interpretation. The goal we address in this work is to assist the ultrasound examiner and partially alleviate the burden of interpretation. We propose to address this goal with visualization that provides clear cues on the orientation and the correspondence between anatomy and the data being imaged. Our system analyzes the stream of 3D ultrasound data and in real-time identifies distinct features that are basis for a dynamically deformed mesh model of the heart. The heart mesh is composited with the original ultrasound data to create the data-to-anatomy correspondence. The visualization is broadcasted over the internet allowing, among other opportunities, a direct visualization on the patient on a tablet computer. The examiner interacts with the transducer and with the visualization parameters on the tablet. Our system has been characterized by domain specialist as useful in medical training and for navigating occasional ultrasound users. © 2012 ACM.

关键词： Visualization

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On symmetries of non-plane trees in a non-uniform model 14

On symmetries of non-plane trees in a non-uniform model

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14th Workshop on Analytic Algorithmics and Combinatorics 2017, ANALCO 2017

作者： Cichoń, Jacek Magnery, Abram Szpankowskiz, Wojciech Turowskix, Krzysztof Department of Computer Science Faculty of Fundamental Problems of Technology Wroclaw University of Science and Technology Wroclaw Poland Coordinated Science Lab. Univ. of Illinois at Urbana-Champaign UrbanaIL United States Dept. of Algorithms and System Modeling Gdańsk University of Technology Gdansk Poland Department of Computer Science Purdue University IN47907 United States

ISBN: (纸本)9781611974775

Binary trees come in two varieties: plane trees, often simply called binary trees, and non-plane trees, in which the order of subtrees does not matter. Nonplane trees find many applications;for example in modeling epidemics, in studying phylogenetic trees, and as models in data compression. While binary trees have been studied very extensively, non-plane trees still pose some challenges. Moreover, in most analyses a uniform probabilistic model is assumed;that is, a tree is selected uniformly from among all trees. Such a model limits significantly applications of the analysis. In this paper we study by analytic techniques non-plane trees in a non-uniform model. In our model, we grow the tree on n leaves by selecting randomly a leaf and appending two children to it. We can show that this is equivalent to an alternative model, also used to analyze the averagecase performance of binary search trees, that is more easily amenable to study by recurrences and generating functions. Here, one of the most important questions is the number of symmetries in such trees (i.e., the number of internal nodes with two isomorphic subtrees), or the sizes of such symmetric subtrees. We first present a functional-differential equation characterizing tree symmetries, and then analyze it. In this conference paper we focus on the expected number of symmetries, the size of symmetric subtrees, and the tree entropy. © Copyright by SIAM.

关键词： Entropy

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Model-based rendezvous calibration of mobile sensor networks for monitoring air quality

Model-based rendezvous calibration of mobile sensor networks...

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IEEE Sensors

作者： A. Arfire A. Marjovi A. Martinoli Distrib. Intell. Syst. & Algorithms Lab. Sch. of Archit. Civil & Environ. Eng. Ecole Polytech. Fed. de Lausanne Lausanne Switzerland

ISBN: (纸本)9781479982042

Mobile Wireless Sensor Networks (WSNs) hold the potential to constitute a real game changer for our understanding of urban air pollution, through a significant augmentation of spatial resolution in measurement. However, temporal drift, cross-sensitivity and effects caused by varying environmental conditions (e.g., temperature) in low-cost chemical sensors (typically used in mobile WSNs) pose a tough challenge for reliable calibration. Based on state-of-the-art rendezvous calibration methods, we propose a novel model-based method for automatically estimating the baseline and gain characteristics of low-cost chemical sensors taking temporal drift and temperature dependencies of the sensors into account. The performance of our algorithm is evaluated using data gathered by our long-term mobile sensor network deployment, developed within the *** OpenSense II project1 in Lausanne, Switzerland. We show that, in a realistic context of sparse and irregular rendezvous events, our method consistently improves rendezvous calibration performance for single-hop online calibration.

关键词： Sensor networks rendezvous Air quality CHEMICAL SENSOR air quality monitoring Mobile ATMOSPHERIC HAZE

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A hierarchy machine: Learning to optimize from nature and humans

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Complexity 2003年第5期8卷 36-45页

作者： Pelikan, Martin Goldberg, David E. Illinois Genetic Algorithms Lab. Department of General Engineering Univ. Illinois at Urbana-Champaign Urbana IL 61801 104 S. Mathews Avenue United States

This article proposes a competent hierarchical optimization method called the hierarchical Bayesian optimization algorithm (hBOA). hBOA extends the Bayesian optimization algorithm (BOA) by incorporating three important features for robust and scalab.e optimization of hierarchical problems: proper decomposition, chunking, and preservation of alternative solutions. Additionally, the article proposes a class of difficult hierarchical problems called hierarchical traps. hBOA is shown to provide a scalab.e solution to the class of hierarchically decomposable problems and anything easier. Specifically, hBOA can solve hierarchical traps and other nearly decomposable problems in approximately O(n^1.55 log n) to O(n²) function evaluations, where n is the number of decision variables in the problem. © 2003 Wiley Periodicals, Inc.

关键词： Bayesian optimization algorithm Decomposable problems Hierarchical traps

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Formal methods and software engineering for DL Security, safety and productivity for DL systems development

arXiv

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arXiv 2019年

作者： Hains, Gaétan J.D.R. Jakobsson, Arvid Khmelevsky, Youry Huawei Parallel and Distributed Algorithms Lab. Huawei Paris Research Center Boulogne Billancourt France LACL Univ. Paris-Est Créteil France LIP6 Database and Machine Learning Department Sorbonne University Paris France Comp.Sc. Okanagan College Canada

Deep Learning (DL) techniques are now widespread and being integrated into many important systems. Their classification and recognition abilities ensure their relevance for multiple application domains. As machine-learning that relies on training instead of algorithm programming, they offer a high degree of productivity. But they can be vulnerable to attacks and the verification of their correctness is only just emerging as a scientific and engineering possibility. This paper is a major update of a previously-published survey, attempting to cover all recent publications in this area. It also covers an even more recent trend, namely the design of domain-specific languages for producing and training neural nets. Copyright © 2019, The Authors. All rights reserved.

关键词： Productivity

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Base station antenna selection for low-resolution ADC systems

arXiv

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arXiv 2019年

作者： Choi, Jinseok Sung, Junmo Prasad, Narayan Qi, Xiao-Feng Evans, Brian L. Gatherer, Alan Department of Electrical and Computer Engineering University of Texas at Austin AustinTX United States Samsung in Dallas TX United States Radio Algorithms Research Group Futurewei Technologies NJ Research Center BridgewaterNJ United States Wireless Access Lab. Futurewei Technologies Legacy Dr. PlanoTX United States

This paper investigates antenna selection at a base station with large antenna arrays and lowresolution analog-to-digital converters. For downlink transmit antenna selection for narrowband channels, we show (1) a selection criterion that maximizes sum rate with zero-forcing precoding equivalent to that of a perfect quantization system;(2) maximum sum rate increases with number of selected antennas;(3) derivation of the sum rate loss function from using a subset of antennas;and (4) unlike highresolution converter systems, sum rate loss reaches a maximum at a point of total transmit power and decreases beyond that point to converge to zero. For wideband orthogonal-frequency-divisionmultiplexing (OFDM) systems, our results hold when entire subcarriers share a common subset of antennas. For uplink receive antenna selection for narrowband channels, we (1) generalize a greedy antenna selection criterion to capture tradeoffs between channel gain and quantization error;(2) propose a quantization-aware fast antenna selection algorithm using the criterion;and (3) derive a lower bound on sum rate achieved by the proposed algorithm based on submodular functions. For wideband OFDM systems, we extend our algorithm and derive a lower bound on its sum rate. Simulation results validate theoretical analyses and show increases in sum rate over conventional algorithms. Copyright © 2019, The Authors. All rights reserved.

关键词： Antenna arrays

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Towards fully autonomous driving: Systems and algorithms

Towards fully autonomous driving: Systems and algorithms

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IEEE Symposium on Intelligent Vehicle

作者： Jesse Levinson Jake Askeland Jan Becker Jennifer Dolson David Held Soeren Kammel J. Zico Kolter Dirk Langer Oliver Pink Vaughan Pratt Michael Sokolsky Ganymed Stanek David Stavens Alex Teichman Moritz Werling Sebastian Thrun Towards Fully Autonomous Driving: Systems and Algorithms USA Volkswagen Electronics Res. Lab. Palo Alto CA USA Robert Bosch LLC USA Bosch RTC USA Massachusetts Inst. of Tech. USA Volkswagen of America USA Robert Bosch GmbH USA BMW Group Forschung und Tech. GmbH USA Stanford Univ. & Google Inc USA

In order to achieve autonomous operation of a vehicle in urban situations with unpredictable traffic, several realtime systems must interoperate, including environment perception, localization, planning, and control. In addition, a robust vehicle platform with appropriate sensors, computational hardware, networking, and software infrastructure is essential. We previously published an overview of Junior, Stanford's entry in the 2007 DARPA Urban Challenge. This race was a closed-course competition which, while historic and inciting much progress in the field, was not fully representative of the situations that exist in the real world. In this paper, we present a summary of our recent research towards the goal of enabling safe and robust autonomous operation in more realistic situations. First, a trio of unsupervised algorithms automatically calibrates our 64-beam rotating LIDAR with accuracy superior to tedious hand measurements. We then generate high-resolution maps of the environment which are subsequently used for online localization with centimeter accuracy. Improved perception and recognition algorithms now enable Junior to track and classify obstacles as cyclists, pedestrians, and vehicles; traffic lights are detected as well. A new planning system uses this incoming data to generate thousands of candidate trajectories per second, choosing the optimal path dynamically. The improved controller continuously selects throttle, brake, and steering actuations that maximize comfort and minimize trajectory error. All of these algorithms work in sun or rain and during the day or night. With these systems operating together, Junior has successfully logged hundreds of miles of autonomous operation in a variety of real-life conditions.

关键词： Trajectory Vehicles Calibration Laser beams Vehicle dynamics Planning Software

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Illustrative visualization

Illustrative visualization

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VIS 05: IEEE Visualization 2005, Proceedings

作者： Viola, Ivan Gröller, Meister E. Hadwiger, Markus Bühler, Katja Preim, Bernhard Sousa, Mario Costa Ebert, David S. Stredney, Don Kanitsar, Armin Bruckner, Stefan Grimm, Sören Svakhine, Nikolai A. Jang, Yun Gaithert, Kelly Tietjen, Christian Krüger, Arno Peitgen, Heinz-Otto Isenberg, Tobias Hintze, Jana Hertel, Ilka Strauß, Gero Institute of Computer Graphics and Algorithms Vienna University of Technology Austria VRVis Research Center Vienna Austria Department of Simulation and Graphics University of Magdeburg Germany Department of Computer Science University of Calgary Canada School of Electrical and Computer Engineering Purdue University United States Ohio Supercomputer Center United States Institute of Computer Graphics and Algorithms Vienna University of Technology Austria VRVis Research Center Vienna Austria Electrical and Computer Engineering Purdue University United States IEEE Austria Department of Computer Science University of Calgary Canada Department of Computer Science Computer Graphics Research Lab. University of Calgary Canada Purdue University United States Ohio Supercomputer Center United States University of Texas Austin United States Interface Laboratory United States Biomedical Applications United States Department of Simulation and Graphics Otto-von-Guericke-University of Magdeburg Germany Otto-von-Guericke-University of Magdeburg FIN/ISG Germany Institute for Simulation and Graphics Department for Computer Science Otto-von-Guericke-University of Magdeburg Universitaetsplatz 2 39106 Magdeburg Germany Center for Medical Diagnosic Systems and Visualization Universitaetsallee 29 28359 Bremen Germany Department of Simulation and Graphics Otto-von-Guericke University of Magdeburg Germany ENT Department University Hospital of Leipzig Germany

ISBN: (纸本)0780394623

The tutorial presents state-of-the-art visualization techniques inspired by traditional technical and medical illustrations. Such techniques exploit the perception of the human visual system and provide effective visual abstractions to make the visualization clearly understandable. Visual emphasis and abstraction has been used for expressive presentation from prehistoric paintings to nowadays scientific and medical illustrations. Many of the expressive techniques used in art are adopted in computer graphics, and are denoted as illustrative or non-photorealistic rendering. Different stroke techniques, or brush properties express a particular level of abstraction. Feature emphasis or feature suppression is achieved by combining different abstraction levels in illustrative rendering. Challenges in visualization research are very large data visualization as well as multi-dimensional data visualization. To effectively convey the most important visual information there is a significant need for visual abstraction. For less relevant information the dedicated image space is reduced to enhance more prominent features. The discussed techniques in the context of scientific visualization are based on iso-surfaces and volume rendering. Apart from visual abstraction, i.e., illustrative representation, the visibility of prominent features can be achieved by illustrative visualization techniques such as cut-away views or ghosted views. The structures that occlude the most prominent information are suppressed in order to clearly see more interesting parts. A different smart way to provide information on the data is using exploded views or other types of deformation. Furthermore intuitive feature classification via 3D painting and manipulation with the classified data including lab.l placement is presented. Discussed non-photorealistic and illustrative techniques from visualization and graphics are shown from the perspective as tools for illustrators from medicine, botany, archeology

关键词： Visualization

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