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Proving path non-existence using sampling and alpha shapes

Zoe McCarthy, Timothy Bretl, Seth Hutchinson
2012 2012 IEEE International Conference on Robotics and Automation  
These samples are then weighted by their generalized penetration distance, and used to construct alpha shapes.  ...  Such planners, while typically either resolution complete or probabilistically complete, are not able to determine when a path does not exist, and therefore would otherwise rely on heuristics to determine  ...  ALGORITHM TO PROVE PATH NON-EXISTENCE In this section we develop the necessary algorithms to prove that no path exists between two points.  ... 
doi:10.1109/icra.2012.6225300 dblp:conf/icra/McCarthyBH12 fatcat:cjypr6yupzdl7l7vonsv6phsxe

Energy-Bounded Caging: Formal Definition and 2-D Energy Lower Bound Algorithm Based on Weighted Alpha Shapes

Jeffrey Mahler, Florian T. Pokorny, Zoe McCarthy, A. Frank van der Stappen, Ken Goldberg
2016 IEEE Robotics and Automation Letters  
EBCA-2D builds on recent results in collision detection and the computational geometric theory of weighted α-shapes and runs in O(s 2 + sn 2 ) time where s is the number of samples, n is the total number  ...  to find escape paths with lower energy.  ...  We then use connectivity checking to prove non-existence of escape paths based on recent results of [28] .  ... 
doi:10.1109/lra.2016.2519145 dblp:journals/ral/MahlerPMSG16 fatcat:uamrd24qhjfxbinghgxf7p2bny

A Decomposition-Based Approach to Reasoning about Free Space Path-Connectivity for Rigid Objects in 2D [article]

Anastasiia Varava, J. Frederico Carvalho, Danica Kragic, Florian T. Pokorny
2017 arXiv   pre-print
whether there exists a collision-free path between two given configurations, and to verify whether an object can escape arbitrarily far from its initial configuration -- i.e., whether the object is caged  ...  To address these problems, we decompose the configuration space into a set of two-dimensional slices, approximate them as two-dimensional alpha-complexes, and then study the relations between them.  ...  The authors are with the Robotics, Perception, and Learning Lab, School of Computer Science and Communication, KTH The Royal Insti-  ... 
arXiv:1710.10089v1 fatcat:tcdivajrlbfpfnf34swyh2mkha

Probabilities on cladograms: introduction to the alpha model [article]

Daniel J. Ford
2005 arXiv   pre-print
The number of cherries on a random alpha tree is shown to be asymptotically normal with known mean and variance. Finally the shape of published phylogenies is examined, using trees from Treebase.  ...  This model is Markovian self-similar, deletion-stable (sampling consistent), and passes through the Yule, Uniform and Comb models.  ...  All binary trees from Treebase (as of Nov.2004 ) are analyzed and their shapes compared using the alpha model.  ... 
arXiv:math/0511246v1 fatcat:kdsfhsfsu5h3linz432i5xl3nu

Phase Analysis of Explosive Welded Ti-Cr/Ni Steel in As-Received State and after Heat Treatment Using Synchrotron/ Analiza Fazowa Połączenia Ti-Cr/Stali Ni Wytworzonego Metodą Zgrzewania Wybuchowego W Stanie Wyjściowym Oraz Po Obróbce Termicznej Z Wykorzystaniem Promieniowania Synchrotonowego

D. Ostroushko, E. Mazancová, K. Saksl, O. Milković
2014 Archives of Metallurgy and Materials  
The work is focused on interface shape line, inhomogeneities in vicinity of the wave joint both in basic material and in vicinity of weld line of the Ti and Cr/Ni stainless steel (SS) matrix.  ...  Surface coatings protection is one of the most important processes ensuring efficient and economic use of basic materials, mostly of lower-quality.  ...  process engineering" and No.  ... 
doi:10.2478/amm-2014-0273 fatcat:h7x2pz4k2bb3batpvhaku6hvf4

A conditional independence test for causality in econometrics [article]

Jaime Sevilla, Alexandra Mayn
2021 arXiv   pre-print
We then show how to apply this heuristic test on a price-demand and a firm loan-productivity problem.  ...  The Y-test is a useful tool for detecting missing confounders in the context of a multivariate regression.However, it is rarely used in practice since it requires identifying multiple conditionally independent  ...  Identifying a context S that blocks all non-causal paths between X and Y 2.  ... 
arXiv:2107.09765v1 fatcat:opdudrelr5aujbxpt6bbdgjqbq

Minimum area enclosure and alpha hull of a set of freeform planar closed curves

A.V. Vishwanath, R. Arun Srivatsan, M. Ramanathan
2013 Computer-Aided Design  
We also extend the notion of α-hull of a point set to the set of closed curves and explore the relation between alpha hull (using negative alpha) and the MAE.  ...  Convex hull, which gives a convex enclosure of the given set, concave hull, which generates nonconvex polygons and other variants such as α-hull, poly hull, r-shape and s-shape etc. have been proposed.  ...  The alpha shape uses a real parameter α, variations of which leads to a family of shapes. The output of the alpha shape need not necessarily be convex nor connected.  ... 
doi:10.1016/j.cad.2012.12.001 fatcat:mfrrlhsbufb5hcyotv3n5rymga

Improved image quilting

Jeremy Long, David Mould
2007 Graphics Interface  
Our method uses an alternate distance metric for Dijkstra's algorithm [3] , and as a result we are able to prevent the path from taking short cuts through high cost areas, as can sometimes be seen in traditional  ...  In this paper, we present an improvement to the minimum error boundary cut, a method of shaping texture patches for nonparametric texture synthesis from example algorithms such as Efros and Freeman's Image  ...  This work was supported by the University of Saskatchewan and by NSERC RGPIN299070-04.  ... 
doi:10.1145/1268517.1268559 dblp:conf/graphicsinterface/LongM07 fatcat:c6ahmujtojhfvdu6qdzleuuoxy

Financial literacy as a mediator of personal financial health during COVID-19: A structural equation modelling approach

Swati Anand, Kushendra Mishra, Vishal Verma, Taruna Taruna
2020 Emerald Open Research  
The research design is descriptive and exploratory using snowball sampling technique. The data was collected through an internet survey. In total, 400 survey responses were obtained.  ...  After testing the measurement model for key validity dimensions, the hypothesised causal relationships are examined in several path models.  ...  We used a web-based survey questionnaire to collect data through snowball sampling, with a sample size of 400.  ... 
doi:10.35241/emeraldopenres.13735.1 fatcat:q23h6vgjkzgg3nhvnlfyjm7ike

A Framework for Estimating Stream Expression Cardinalities [article]

Anirban Dasgupta, Kevin Lang, Lee Rhodes, Justin Thaler
2016 arXiv   pre-print
To demonstrate its generality, we describe several novel sampling algorithms in our class, and show that they achieve a novel tradeoff between accuracy, space usage, update speed, and applicability.  ...  We identify a broad class of algorithms for solving this problem, and show that the estimators output by any algorithm in this class are perfectly unbiased and satisfy strong variance bounds.  ...  Here is one such example: The non-existence of the required fixed threshold is proved by the above plot of k = 3, h(A) = {0.1, 0.2, 0.4, 0.7, x }. T (x ).  ... 
arXiv:1510.01455v2 fatcat:qzf4czi7zzgp7f2nqctjue4bg4

Research on Parameter Estimation Methods for Alpha Stable Noise in a Laser Gyroscope's Random Error

Xueyun Wang, Kui Li, Pengyu Gao, Suxia Meng
2015 Sensors  
Three widely used estimation methods-quantile, empirical characteristic function (ECF) and logarithmic moment method-are analyzed in contrast with Monte Carlo simulation in this paper.  ...  The cumulative probability density curve of the experimental data fitted by an alpha stable distribution is better than that by a Gaussian distribution, which verifies the existence of alpha stable noise  ...  Pengyu Gao was mainly responsible for the experimentation and Suxia Meng analyzed the experimental data to prove the theory proposed by Xueyun Wang and Kui Li.  ... 
doi:10.3390/s150818550 pmid:26230698 pmcid:PMC4570335 fatcat:y7afx2oxobeyxhsdldlwypiuhq

Research on the impact of cooperative behaviors in alliance organization in member psychological contract

Song Dongfeng
2012 African Journal of Business Management  
Then, empirical test is undertaken by questionnaire, and then the conclusions are drawn.  ...  Take the alliance of Chinese hotels for example; it is necessary to adopt sampling investigation to study the impact of cooperative behaviors selection due to psychological contracts.  ...  In this way, many hotel alliances are shaped, such as hotel affiliates, hotel commonwealth, hotel companies and so on. Non-equity member enterprises are selected as investigating objects.  ... 
doi:10.5897/ajbm11.2838 fatcat:cx7u26idhnehzj3pzp5xtebub4

Evaluating natural language processing models with generalization metrics that do not need access to any training or testing data [article]

Yaoqing Yang, Ryan Theisen, Liam Hodgkinson, Joseph E. Gonzalez, Kannan Ramchandran, Charles H. Martin, Michael W. Mahoney
2022 arXiv   pre-print
In this paper, we discuss the performance of natural language processing (NLP) models, and we evaluate various existing and novel generalization metrics.  ...  Our detailed empirical studies show that (i) shape metrics, or the metrics obtained from fitting the shape of the ESDs, perform uniformly better at predicting generalization performance than scale metrics  ...  , Nvidia, Scotiabank, Splunk and VMware.  ... 
arXiv:2202.02842v1 fatcat:3vjc7dveyfag3ie6limwo44bke

Pulse-shape discrimination of surface events in CdZnTe detectors for the COBRA experiment

M. Fritts, J. Tebrügge, J. Durst, J. Ebert, C. Gößling, T. Göpfert, D. Gehre, C. Hagner, N. Heidrich, M. Homann, T. Köttig, T. Neddermann (+8 others)
2014 Nuclear Instruments and Methods in Physics Research Section A : Accelerators, Spectrometers, Detectors and Associated Equipment  
However, the amplitudes cannot be used to identify events near the lateral surfaces. In this paper a method is described to identify lateral surface events by means of their pulse shapes.  ...  Events near the cathode and anode surfaces of a coplanar grid CdZnTe detector are identifiable by means of the interaction depth information encoded in the signal amplitudes.  ...  Acknowledgments The COBRA Experiment would like to thank the Istituto Nazionale di Fisica Nucleare for the use of their laboratory and infrastructure at the Laboratori Nazionali del Gran Sasso, as well  ... 
doi:10.1016/j.nima.2014.02.038 fatcat:xxypiutxtncr5mntckug367bwm

Synthesis of Energy-Bounded Planar Caging Grasps Using Persistent Homology

Jeffrey Mahler, Florian T. Pokorny, Sherdil Niyaz, Ken Goldberg
2018 IEEE Transactions on Automation Science and Engineering  
We implement EBCS-2D using the Persistent Homology Algorithms Toolbox (PHAT) and study performance on a set of seven planar objects and four gripper types.  ...  Experiments suggest that EBCS-2D takes 2-3 minutes on a 6 core processor with 200,000 pose samples. We also confirm that an RRT* motion planner is unable to find escape paths with lower energy.  ...  Acknowledgements: This research was performed at the AUTOLAB at UC Berkeley in affiliation with the AMP Lab, BAIR, and the CITRIS "People and Robots" (CPAR) Initiative: http://robotics.citris-uc.org.  ... 
doi:10.1109/tase.2018.2831724 fatcat:2cjslyga3jcf3bidet7eplhkha
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