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HGeoHashBase: an optimized storage model of spatial objects for location-based services

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Frontiers of Computer Science 2020年第1期14卷 208-218页

作者： Jingwei ZHANG Chao YANG Qing YANG Yuming LIN Yanchun ZHANG Guangxi Key Laboratory of Trusted Software Guilin University of Electronic TechnologyGuilin 541004China Guangxi Cooperative Innovation Center of Cloud Computing and Big Data Guilin University of Electronic TechnologyGuilin 541004China Guangxi Key Laboratory of Automatic Measurement Technology and Instrument Guilin University of Electronic TechnologyGuilin 541004China Centre for Applied Informatics College of Engineering and ScienceVictoria UniversityMelbourne 8001Australia

Many location-based services need to query objects existing in a specific space,such as location-based tourism resource *** a large number of spatial objects and the real-time object access requirements of location-based services pose a big challenge for spatial object storage and query *** this paper,we propose HGeoHashBase,an improved storage model by integrating GeoHash with key-value structure,to organize spatial objects for efficient range *** is responsible for spatial encoding and key-value structure as underlying data *** the similarity of the encodings for objects in the close geographical locations and the multi-version data mechanism are blended into the proposed model *** the tradeoff between encoding precision and query performance,a theoretical proof is *** experiments are designed and conducted,whose results show that the proposed model can gain significant performance improvement.

关键词： location-based services distributed storage model storage and access optimization

Non-Gaussian-state generation with time-gated photon detection

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Physical Review Research 2023年第3期5卷 033156-033156页

作者： Tatsuki Sonoyama Kazuma Takahashi Baramee Charoensombutamon Sachiko Takasu Kaori Hattori Daiji Fukuda Kosuke Fukui Kan Takase Warit Asavanant Jun-ichi Yoshikawa Mamoru Endo Akira Furusawa Department of Applied Physics School of Engineering The University of Tokyo 7-3-1 Hongo Bunkyo-ku Tokyo 113-8656 Japan National Institute of Advanced Industrial Science and Technology Tsukuba Ibaraki 305-8563 Japan AIST-UTokyo Advanced Operando-Measurement Technology Open Innovation Laboratory Tsukuba Ibaraki 305-8563 Japan Optical Quantum Computing Research Team RIKEN Center for Quantum Computing 2-1 Hirosawa Wako Saitama 351-0198 Japan

Non-Gaussian states of light, which are essential in fault-tolerant and universal optical quantum computation, are typically generated by a heralding scheme using photon detectors. Recently, it has been theoretically shown that the large timing jitter of the photon detectors deteriorates the purity of the generated non-Gaussian states [T. Sonoyama et al., Phys. Rev. A 105, 043714 (2022)]. Here, we circumvent this problem by time-gated photon detection and generate non-Gaussian states with Wigner negativity using continuous-wave light. We use a fast optical switch for time gating to effectively improve the timing jitter of a photon-number-resolving detector based on a transition edge sensor from 50 ns to 10 ns. As a result, we generate non-Gaussian states with Wigner negativity of −0.011±0.004 (ℏ=1), which cannot be observed without the time-gated photon detection method. These results confirm the effect of the timing jitter on non-Gaussian state generation experimentally for the first time. The proposed time-gated photon detection method would be useful for high-purity non-Gaussian state preparation in optical quantum information processing.

关键词： Quantum optics Quantum state engineering Quantum states of light Single-photon detectors

POINTWISE ESTIMATES FOR THE FUNDAMENTAL SOLUTIONS OF HIGHER ORDER SCHRÖDINGER EQUATIONS IN ODD DIMENSIONS I: LOW DIMENSIONAL CASE

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arXiv 2024年

In this paper, for any odd n and any integer m ≥ 1 with n tu(x, t) = ((−∆)m + V(x))u(x, t), t ∈ , x ∈ n, where V is a real-valued potential with certain decay. Let Pac(H) denote the projection onto the absolutely continuous spectrum space of H = (−∆)m + V, and assume that H has no positive embedded eigenvalue. Our main result says that e−itHPac(H) has integral kernel K(t, x, y) satisfying (Equation presented), where the constants C, h > 0, and h can be specified by m, n and the zero energy resonances of H. A similar result for smoothing operators like (Equation presented) is also given. One of the main novelties lies in a new and unified approach to obtain the asymptotic expansions of perturbed resolvents under various types of zero energy resonances. © 2024, CC0.

关键词： Schrodinger equation

A Parallelizable Counterfactual Generation Method Based on Gradient Optimization

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A Parallelizable Counterfactual Generation Method Based on G...

International Conference on Parallel and Distributed Systems (ICPADS)

作者： Haorun Ding Xuesong Jiang Key Laboratory of Computing Power Network and Information Security Ministry of Education Shandong Computer Science Center Qilu University of Technology (Shandong Academy of Sciences) Jinan China Shandong Engineering Research Center of Big Data Applied Technology Faculty of Computer Science and Technology Qilu University of Technology (Shandong Academy of Sciences) Jinan China Shandong Provincial Key Laboratory of Computer Networks Shandong Fundamental Research Center for Computer Science Jinan China Quan Cheng Laboratory Jinan China State Key Laboratory of High-end Server & Storage Technology Jinan China

Post-hoc explanations are important for people to understand the predictions of explanation models. One class of methods in post-hoc explanation is the generation of counterfactuals, where a hypothetical example is obtained by perturbing the inputs to show how one could obtain a different prediction from the decision model. Counter-factual explanations should satisfy several properties: One is that counterfactuals generated under specific scenarios and constraints should be feasible for users, i.e., they should accommodate different causal constraints. The other is that it is more desirable for users to have a wider variety of viable examples, i.e., counterfactual diversity. To this end, we propose a parallelizable method based on gradient optimization. We partition the input feasible domains, perform counterfactual generation independently for each feasible domain, and then parallelize the counterfactual generation process for each feasible domain. Experimental results show that our approach effectively improves the diversity, sparsity, and proximity of the generated counterfactual instances on the public datasets Adult-Income, Lending-Club, German-Credit, and COMPAS compared to other models.

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Sumanene monolayer of pure carbon: a two-dimensional Kagome-analogy lattice with desirable band gap, ultrahigh carrier mobility and strong exciton binding energy

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arXiv 2023年

作者： Shi, Xiaoran Gao, Weiwei Liu, Hongsheng Fu, Zhen-Guo Zhang, Gang Zhang, Yong-Wei Gao, Junfeng Zhao, Jijun Key Laboratory of Materials Modification by Laser Ion and Electron Beams Dalian University of Technology Ministry of Education Dalian116024 China Institute of Applied Physics and Computational Mathematics Beijing100088 China Institute of High Performance Computing A*STAR Singapore138632 Singapore

Design and synthesis of novel two-dimensional (2D) materials that possess robust structural stability and unusual physical properties may open up enormous opportunities for device and engineering applications. Herein we propose a 2D sumanene lattice that be regarded as a derivative of the conventional Kagome lattice. Our tight-binding analysis demonstrates sumanene lattice contains two sets of Dirac cones and two sets of flat bands near the Fermi surface, distinctively different from the Kagome lattice. Using first-principles calculations, we theoretically suggest two possible routines for realization of stable 2D sumanene monolayers (named as α phase and β phase), and α-sumanene monolayer can be experimentally synthesized with chemical vapor deposition using C21H12 as a precursor. Small binding energies on Au(111) surface (e.g. -37.86 eV/Å2 for α phase) signify the possibility of their peel-off after grown on the noble metal substrate. Importantly, our GW plus Bethe-Salpeter equation calculations demonstrate both monolayers have moderate band gaps (1.94 eV for α) and ultrahigh carrier mobilities (3.4×104 cm2V−1s−1 for α). In particular, αsumanene monolayer possesses a strong exciton binding energy of 0.73 eV, suggesting potential applications in optics. Copyright © 2023, The Authors. All rights reserved.

关键词： Monolayers

Optimal experimental design: Formulations and computations

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arXiv 2024年

作者： Huan, Xun Jagalur, Jayanth Marzouk, Youssef University of Michigan 1231 Beal Ave Ann ArborMI48109 United States Center for Applied Scientific Computing Lawrence Livermore National Laboratory 7000 East Ave LivermoreCA94550 United States Massachusetts Institute of Technology 77 Massachusetts Ave CambridgeMA02139 United States

Questions of ‘how best to acquire data’ are essential to modeling and prediction in the natural and social sciences, engineering applications, and beyond. Optimal experimental design (OED) formalizes these questions and creates computational methods to answer them. This article presents a systematic survey of modern OED, from its foundations in classical design theory to current research involving OED for complex models. We begin by reviewing criteria used to formulate an OED problem and thus to encode the goal of performing an experiment. We emphasize the flexibility of the Bayesian and decision-theoretic approach, which encompasses information-based criteria that are well-suited to nonlinear and non-Gaussian statistical models. We then discuss methods for estimating or bounding the values of these design criteria;this endeavor can be quite challenging due to strong nonlinearities, high parameter dimension, large per-sample costs, or settings where the model is implicit. A complementary set of computational issues involves optimization methods used to find a design;we discuss such methods in the discrete (combinatorial) setting of observation selection and in settings where an exact design can be continuously parameterized. Finally we present emerging methods for sequential OED that build non-myopic design policies, rather than explicit designs;these methods naturally adapt to the outcomes of past experiments in proposing new experiments, while seeking coordination among all experiments to be performed. Throughout, we highlight important open questions and challenges. © 2024, CC BY.

关键词： Design of experiments

Modeling the Absence of Framing Effect in an Experience-based Covid-19 Disease Problem 18

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Modeling the Absence of Framing Effect in an Experience-base...

18th International Conference on Cognitive Modelling, ICCM 2020 - Co-located with the 53rd Annual Meeting of the Society for Mathematical Psychology

作者： Sharma, Neha Uttrani, Shashank Dutt, Varun School of Computing Indian Institute of Information Technology Una177220 India Applied Cognitive Sciences Laboratory Indian Institute of Technology Mandi175075 India

ISBN: (纸本)9780998508245

Prior research in decisions from experience (DFE) has investigated people’s consequential decisions after information search both experimentally and computationally. However, prior DFE research has yet to explore how computational cognitive models and their mechanisms could explain the effects of problem framing in experience. The primary objective of this paper is to address this literature gap and develop Instance-based Learning Theory (IBLT) models on the effects of problem framing. Human data was collected on a modified form of the Asian disease problem posed about the COVID-19 pandemic across two between-subject conditions: gain (N = 40) and loss (N = 40). The COVID-19 problem was presented as "lives saved" in the gain condition and "lives lost" in the loss condition. Results revealed the absence of the classical framing effect, exhibiting no preference reversal between gain and loss conditions in experience. Next, an IBL model was developed and calibrated to the data obtained in the gain and loss problems. The calibrated model was generalized to the non-calibrated conditions (gain to loss and loss to gain). An IBL model with ACT-R default parameters was also generalized. Results revealed that the IBL model with calibrated parameters explained human choices more accurately compared to the IBL model with ACT-R default parameters. Also, participants showed greater reliance on recency and frequency of outcomes and less variability in their choices across both gain and loss conditions. We highlight the main implications of our findings for the cognitive modeling community. © 2020 Proceedings of ICCM 2020 - 18th International Conference on Cognitive Modelling. All Rights Reserved.

关键词： computational models COVID-19 disease problem experience framing gain individual choice loss sampling

Harnessing semantic segmentation masks for accurate facial attribute editing

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Harnessing semantic segmentation masks for accurate facial a...

作者： Chen, Peng Xiao, Qi Xu, Jian Dong, Xiaoli Sun, Linjun Li, Weijun Ning, Xin Wang, Guojun Chen, Ziheng Laboratory of Artificial Neural Networks and High-Speed Circuits Institute of Semiconductors Chinese Academy of Sciences Beijing China Center of Materials Science and Optoelectronics Engineering & School of Microelectronics University of Chinese Academy of Sciences Beijing China College of Physics SiChuan University Sichuan China Cognitive Computing Technology Joint Laboratory WAVE Group Beijing China Applied Math and Statistics Department Stony Brook University Stony BrookNY United States

In recent years, with the rapid development of adversarial learning technology, facial attribute editing has made great success in a number of areas. Realistic visual effect, invariant identity information, and accurate editing area are the three key issues of facial attribute editing. Unfortunately, most researches focus on the former two problems. However, lack of awareness of the accurate editing area in the task is the main reason for damaging attribute-irrelevant details. To address this issue, this article proposes a novel facial attribute editing algorithm—a generative adversarial network (GAN) with semantic masks—from the perspective of editing location accuracy. By generating the mask with respect to attribute-related areas, the semantic segmentation network can only constrain the manipulation in the target region while not harming any attribute-irrelevant details. The GAN is then combined with the semantic segmentation network to formulate the entire framework, which is referred to as SM-GAN. Extensive experiments on the public datasets CelebA and LFWA prove that the presented method can not only ensure that the attribute manipulation is realistic, but also allow attribute-irrelevant regions to remain unchanged. Moreover, it can also simultaneously edit multiple facial attributes. © 2020 John Wiley & Sons, Ltd.

关键词： Generative adversarial networks

A posteriori error estimation for an interior penalty virtual element method of Kirchhoff plates

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arXiv 2024年

作者： Feng, Fang Hu, Yuming Yu, Yue Zhao, Jikun School of Mathematics and Statistics Nanjing University of Science and Technology Nanjing China Hunan Key Laboratory for Computation and Simulation in Science and Engineering Key Laboratory of Intelligent Computing and Information Processing of Ministry of Education National Center for Applied Mathematics in Hunan School of Mathematics and Computational Science Xiangtan University Hunan Xiangtan411105 China School of Mathematics and Statistics Zhengzhou University Zhengzhou450001 China

In this paper, we develop a residual-type a posteriori error estimation for an interior penalty virtual element method (IPVEM) for the Kirchhoff plate bending problem. Building on the work in [18], we adopt a modified discrete variational formulation that incorporates the H1-elliptic projector in the jump and average terms. This allows us to simplify the numerical implementation by including the H1-elliptic projector in the computable error estimators. We derive the reliability and efficiency of the a posteriori error bound by constructing an enriching operator and establishing some related error estimates that align with C0-continuous interior penalty finite element methods. As observed in the a priori analysis, the interior penalty virtual elements exhibit similar behaviors to C0continuous elements despite its discontinuity. This observation extends to the a posteriori estimate since we do not need to account for the jumps of the function itself in the discrete scheme and the error estimators. As an outcome of the error estimator, an adaptive VEM is introduced by means of the mesh refinement strategy with the one-hanging-node rule. Numerical results from several benchmark tests confirm the robustness of the proposed error estimators and show the efficiency of the resulting adaptive VEM. Copyright © 2024, The Authors. All rights reserved.

关键词： Discrete element methods