The Experts below are selected from a list of 76755 Experts worldwide ranked by ideXlab platform
Masafumi Yamashita - One of the best experts on this subject based on the ideXlab platform.
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brief announcement pattern formation problem for synchronous mobile robots in the three dimensional euclidean space
Principles of Distributed Computing, 2016Co-Authors: Yukiko Yamauchi, Taichi Uehara, Masafumi YamashitaAbstract:We investigate the pattern formation problem that requires a swarm of autonomous mobile robots to form a given target pattern in the three-dimensional Euclidean space. We show a necessary and sufficient condition for synchronous robots to form a given target pattern from an Initial Configuration. We give a pattern formation algorithm for solvable instances that does not need any local memory at each robot.
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pattern formation problem for synchronous mobile robots in the three dimensional euclidean space
arXiv: Distributed Parallel and Cluster Computing, 2015Co-Authors: Yukiko Yamauchi, Taichi Uehara, Masafumi YamashitaAbstract:We consider a swarm of autonomous mobile robots each of which is an anonymous point in the three-dimensional Euclidean space (3D-space) and synchronously executes a common distributed algorithm. We investigate the pattern formation problem that requires the robots to form a given target pattern from an Initial Configuration and characterize the problem by showing a necessary and sufficient condition for the robots to form a given target pattern. The pattern formation problem in the two dimensional Euclidean space (2D-space) has been investigated by Suzuki and Yamashita (SICOMP 1999, TCS 2010), and Fujinaga et al. (SICOMP 2015). The symmetricity $\rho(P)$ of a Configuration (i.e., the positions of robots) $P$ is intuitively the order of the cyclic group that acts on $P$. It has been shown that fully-synchronous (FSYNC) robots can form a target pattern $F$ from an Initial Configuration $P$ if and only if $\rho(P)$ divides $\rho(F)$. We extend the notion of symmetricity to 3D-space by using the rotation groups each of which is defined by a set of rotation axes and their arrangement. We define the symmetricity $\varrho(P)$ of Configuration $P$ in 3D-space as the set of rotation groups that acts on $P$ and whose rotation axes do not contain any robot. We show the following necessary and sufficient condition for the pattern formation problem which is a natural extension of the existing results of the pattern formation problem in 2D-space: FSYNC robots in 3D-space can form a target pattern $F$ from an Initial Configuration $P$ if and only if $\varrho(P) \subseteq \varrho(F)$. For solvable instances, we present a pattern formation algorithm for oblivious FSYNC robots. The insight of this paper is that symmetry of mobile robots in 3D-space is sometimes lower than the symmetry of their positions and the robots can show their symmetry by their movement.
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randomized pattern formation algorithm for asynchronous oblivious mobile robots
International Symposium on Distributed Computing, 2014Co-Authors: Yukiko Yamauchi, Masafumi YamashitaAbstract:We present a randomized pattern formation algorithm for asynchronous oblivious (i.e., memory-less) mobile robots that enables formation of any target pattern. As for deterministic pattern formation algorithms, the class of patterns formable from an Initial Configuration I is characterized by the symmetricity (i.e., the order of rotational symmetry) of I, and in particular, every pattern is formable from I if its symmetricity is 1. The randomized pattern formation algorithm ψ PF we present in this paper consists of two phases: The first phase transforms a given Initial Configuration I into a Configuration I′ such that its symmetricity is 1, and the second phase invokes a deterministic pattern formation algorithm ψ CWM by Fujinaga et al. (DISC 2012) for asynchronous oblivious mobile robots to finally form the target pattern.
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locomotion of metamorphic robotic system based on local information extended abstract
Symposium on Reliable Distributed Systems, 2014Co-Authors: Fengqi Chen, Yukiko Yamauchi, Shuji Kijima, Masafumi YamashitaAbstract:Motivated by the molecular robotics project of Japan, we investigate the problem of designing a distribution locomotion algorithm for metamorphic robotic system consisting of homogeneous modules. The algorithm, which works on each module, must navigate it so that the entire system moves in a predetermined direction. We present an algorithm that moves the system eastward, provided that an Initial Configuration is monotone. Then we show the outline of its correctness.
Yukiko Yamauchi - One of the best experts on this subject based on the ideXlab platform.
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brief announcement pattern formation problem for synchronous mobile robots in the three dimensional euclidean space
Principles of Distributed Computing, 2016Co-Authors: Yukiko Yamauchi, Taichi Uehara, Masafumi YamashitaAbstract:We investigate the pattern formation problem that requires a swarm of autonomous mobile robots to form a given target pattern in the three-dimensional Euclidean space. We show a necessary and sufficient condition for synchronous robots to form a given target pattern from an Initial Configuration. We give a pattern formation algorithm for solvable instances that does not need any local memory at each robot.
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pattern formation problem for synchronous mobile robots in the three dimensional euclidean space
arXiv: Distributed Parallel and Cluster Computing, 2015Co-Authors: Yukiko Yamauchi, Taichi Uehara, Masafumi YamashitaAbstract:We consider a swarm of autonomous mobile robots each of which is an anonymous point in the three-dimensional Euclidean space (3D-space) and synchronously executes a common distributed algorithm. We investigate the pattern formation problem that requires the robots to form a given target pattern from an Initial Configuration and characterize the problem by showing a necessary and sufficient condition for the robots to form a given target pattern. The pattern formation problem in the two dimensional Euclidean space (2D-space) has been investigated by Suzuki and Yamashita (SICOMP 1999, TCS 2010), and Fujinaga et al. (SICOMP 2015). The symmetricity $\rho(P)$ of a Configuration (i.e., the positions of robots) $P$ is intuitively the order of the cyclic group that acts on $P$. It has been shown that fully-synchronous (FSYNC) robots can form a target pattern $F$ from an Initial Configuration $P$ if and only if $\rho(P)$ divides $\rho(F)$. We extend the notion of symmetricity to 3D-space by using the rotation groups each of which is defined by a set of rotation axes and their arrangement. We define the symmetricity $\varrho(P)$ of Configuration $P$ in 3D-space as the set of rotation groups that acts on $P$ and whose rotation axes do not contain any robot. We show the following necessary and sufficient condition for the pattern formation problem which is a natural extension of the existing results of the pattern formation problem in 2D-space: FSYNC robots in 3D-space can form a target pattern $F$ from an Initial Configuration $P$ if and only if $\varrho(P) \subseteq \varrho(F)$. For solvable instances, we present a pattern formation algorithm for oblivious FSYNC robots. The insight of this paper is that symmetry of mobile robots in 3D-space is sometimes lower than the symmetry of their positions and the robots can show their symmetry by their movement.
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randomized pattern formation algorithm for asynchronous oblivious mobile robots
International Symposium on Distributed Computing, 2014Co-Authors: Yukiko Yamauchi, Masafumi YamashitaAbstract:We present a randomized pattern formation algorithm for asynchronous oblivious (i.e., memory-less) mobile robots that enables formation of any target pattern. As for deterministic pattern formation algorithms, the class of patterns formable from an Initial Configuration I is characterized by the symmetricity (i.e., the order of rotational symmetry) of I, and in particular, every pattern is formable from I if its symmetricity is 1. The randomized pattern formation algorithm ψ PF we present in this paper consists of two phases: The first phase transforms a given Initial Configuration I into a Configuration I′ such that its symmetricity is 1, and the second phase invokes a deterministic pattern formation algorithm ψ CWM by Fujinaga et al. (DISC 2012) for asynchronous oblivious mobile robots to finally form the target pattern.
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locomotion of metamorphic robotic system based on local information extended abstract
Symposium on Reliable Distributed Systems, 2014Co-Authors: Fengqi Chen, Yukiko Yamauchi, Shuji Kijima, Masafumi YamashitaAbstract:Motivated by the molecular robotics project of Japan, we investigate the problem of designing a distribution locomotion algorithm for metamorphic robotic system consisting of homogeneous modules. The algorithm, which works on each module, must navigate it so that the entire system moves in a predetermined direction. We present an algorithm that moves the system eastward, provided that an Initial Configuration is monotone. Then we show the outline of its correctness.
Harold Widom - One of the best experts on this subject based on the ideXlab platform.
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integral formulas for the asymmetric simple exclusion process
Communications in Mathematical Physics, 2008Co-Authors: Craig A Tracy, Harold WidomAbstract:In this paper we obtain general integral formulas for probabilities in the asymmetric simple exclusion process (ASEP) on the integer lattice \({\mathbb{Z}}\) with nearest neighbor hopping rates p to the right and q = 1−p to the left. For the most part we consider an N-particle system but for certain of these formulas we can take the \(N\to\infty\) limit. First we obtain, for the N-particle system, a formula for the probability of a Configuration at time t, given the Initial Configuration. For this we use Bethe Ansatz ideas to solve the master equation, extending a result of Schutz for the case N = 2. The main results of the paper, derived from this, are integral formulas for the probability, for given Initial Configuration, that the mth left-most particle is at x at time t. In one of these formulas we can take the \(N\to\infty\) limit, and it gives the probability for an infinite system where the Initial Configuration is bounded on one side. For the special case of the totally asymmetric simple exclusion process (TASEP) our formulas reduce to the known ones.
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integral formulas for the asymmetric simple exclusion process
arXiv: Probability, 2007Co-Authors: Craig A Tracy, Harold WidomAbstract:In this paper we obtain general integral formulas for probabilities in the asymmetric simple exclusion process (ASEP) on the integer lattice with nearest neighbor hopping rates p to the right and q=1-p to the left. For the most part we consider an N-particle system but for certain of these formulas we can take the limit as N goes to infinity. First we obtain, for the N-particle system, a formula for the probability of a Configuration at time t, given the Initial Configuration. For this we use Bethe Ansatz ideas to solve the master equation, extending a result of Schuetz for the case N=2. The main results of the paper, derived from this, are integral formulas for the probability, for given Initial Configuration, that the m'th left-most particle is at x at time t. In one of these formulas we can take the limit as N goes to infinity, and it gives the probability for an infinite system where the Initial Configuration is bounded on one side. For the special case of the totally asymmetric simple exclusion process (TASEP) our formulas reduce to the known ones.
Amade Pouya - One of the best experts on this subject based on the ideXlab platform.
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Debonding of a circular inclusion: Asymmetric propagation of a pair of cracks
International Journal of Solids and Structures, 2019Co-Authors: Sébastien Brisard, Amade PouyaAbstract:Crack propagation associated with two Initially symmetrical cracks located at the interface between an inclusion and the surrounding matrix, subjected to remote traction, is studied by means of Griffith’s energy criterion within the framework of linear elastic fracture mechanics. Using Muskhelishvili’s method of complex potentials, we derive semi-analytical expressions of the stress intensity factor and energy release rate at the crack-tip. Based on these results, we discuss the mode of propagation of the cracks. Our analysis points at the possibility of a single-sided, rather than simultaneous, symmetric crack growth, even if both Initial Configuration and loading are symmetric.
Yicheng Zhang - One of the best experts on this subject based on the ideXlab platform.
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effect of the Initial Configuration for user object reputation systems
Physica A-statistical Mechanics and Its Applications, 2018Co-Authors: Yingying Wu, Yicheng ZhangAbstract:Abstract Identifying the user reputation accurately is significant for the online social systems. For different fair rating parameter q , by changing the parameter values α and β of the beta probability distribution (RBPD) for ranking online user reputation, we investigate the effect of the Initial Configuration of the RBPD method for the online user ranking performance. Experimental results for the Netflix and MovieLens data sets show that when the parameter q equals to 0.8 and 0.9, the accuracy value A U C would increase about 4.5% and 3.5% for the Netflix data set, while the A U C value increases about 1.5% for the MovieLens data set when the parameter q is 0.9. Furthermore, we investigate the evolution characteristics of the A U C value for different α and β , and find that as the rating records increase, the A U C value increases about 0.2 and 0.16 for the Netflix and MovieLens data sets, indicating that online users’ reputations will increase as they rate more and more objects.
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effect of Initial Configuration on network based recommendation
EPL, 2008Co-Authors: Yicheng Zhang, Tao Zhou, Luo Luo JiangAbstract:In this paper, based on a weighted object network, we propose a recommendation algorithm, which is sensitive to the Configuration of Initial resource distribution. Even under the simplest case with binary resource, the current algorithm has remarkably higher accuracy than the widely applied global ranking method and collaborative filtering. Furthermore, we introduce a free parameter β to regulate the Initial Configuration of resource. The numerical results indicate that decreasing the Initial resource located on popular objects can further improve the algorithmic accuracy. More significantly, we argue that a better algorithm should simultaneously have higher accuracy and be more personal. According to a newly proposed measure about the degree of personalization, we demonstrate that a degree-dependent Initial Configuration can outperform the uniform case for both accuracy and personalization strength.
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effect of Initial Configuration on network based recommendation
arXiv: Physics and Society, 2007Co-Authors: Yicheng Zhang, Tao Zhou, Luo Luo JiangAbstract:In this paper, based on a weighted object network, we propose a recommendation algorithm, which is sensitive to the Configuration of Initial resource distribution. Even under the simplest case with binary resource, the current algorithm has remarkably higher accuracy than the widely applied global ranking method and collaborative filtering. Furthermore, we introduce a free parameter $\beta$ to regulate the Initial Configuration of resource. The numerical results indicate that decreasing the Initial resource located on popular objects can further improve the algorithmic accuracy. More significantly, we argue that a better algorithm should simultaneously have higher accuracy and be more personal. According to a newly proposed measure about the degree of personalization, we demonstrate that a degree-dependent Initial Configuration can outperform the uniform case for both accuracy and personalization strength.
