Two anonymous mobile agents navigate synchronously in an anonymous graph and have to meet at a node, using a deterministic algorithm. This is a symmetry breaking task called rendezvous, equivalent to the fundamental t...
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ISBN:
(纸本)9781450361842
Two anonymous mobile agents navigate synchronously in an anonymous graph and have to meet at a node, using a deterministic algorithm. This is a symmetry breaking task called rendezvous, equivalent to the fundamental task of leader election between the agents. When is this feasible in a completely anonymous environment? It is known that agents can always meet if their initial positions are nonsymmetric, and that if they are symmetric and agents start simultaneously then rendezvous is impossible. What happens for symmetric initial positions with non-simultaneous start? Can symmetry between the agents be broken by the delay between their starting times? In order to answer these questions, we consider space-time initial configurations (abbreviated by STIC). A STIC is formalized as [(u, v), delta], where u and v are initial nodes of the agents in some graph and delta is a non-negative integer that represents the difference between their starting times. A STIC is feasible if there exists a deterministic algorithm, even dedicated to this particular STIC, which accomplishes rendezvous for it. Our main result is a characterization of all feasible STICs and the design of a universal deterministic algorithm that accomplishes rendezvous for all of them without any a priori knowledge of the agents. Thus, as far as feasibility is concerned, we completely solve the problem of symmetry breaking between two anonymous agents in anonymous graphs. Moreover, we show that such a universal algorithm cannot work for all feasible STICs in time polynomial in the initial distance between the agents.
In a dynamic environment, close-range and fast-moving interferers transit the resolution cells rapidly, challenging the minimum variance distortionless response (MVDR) beamformer's ability to place accurate notche...
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In a dynamic environment, close-range and fast-moving interferers transit the resolution cells rapidly, challenging the minimum variance distortionless response (MVDR) beamformer's ability to place accurate notches in each interferer's direction. One common approach to overcome this problem is to apply a broader or wider notch at the interferer location. The hybrid double zero (HDZ) MVDR beamformer is a simple and robust method to form a wider notch by implicitly generating second-order notches in the beampattern. The HDZ beampattern is a product of adaptive and fixed factors. The adaptive component has wide second-order notches to suppress moving interferers, while the fixed component improves the white noise gain (WNG) and ensures the array weight vector length matches the array size. However, the challenge for the HDZ beamformer is choosing the ideal number of second-order notches to suppress the moving interferers in a dynamic environment. In practice, the number of moving interferers is unknown and may also change over time. Therefore, an HDZ beamformer with a fixed number of second-order notches may not effectively suppress all the moving interferers if the number of interferers surpasses the number of second-order notches. The need for a time-varying number of second-order notches leads us to design a universal HDZ (UHDZ) beamformer that is universal over this parameter. The UHDZ beamformer rivals the best beamformer in a set of HDZ beamformers with a fixed number of second-order notches without needing prior knowledge of the number of moving interferers or the environment. This paper evaluates the performance of the UHDZ beamformer in simulations and microphone array experiments that include multiple moving interferers.
Facial emotion have great significance in human-computer interaction,virtual reality and people's *** methods for facial emotion privacy mainly concentrate on the perturbation of facial emotion ***,cryptography-b...
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Facial emotion have great significance in human-computer interaction,virtual reality and people's *** methods for facial emotion privacy mainly concentrate on the perturbation of facial emotion ***,cryptography-based perturbation algorithms are highly computationally expensive,and transformation-based perturbation algorithms only target specific recognition *** this paper,we propose a universal feature vector-based privacy-preserving perturbation algorithm for facial *** method implements privacy-preserving facial emotion images on the feature space by computing tiny perturbations and adding them to the original *** addition,the proposed algorithm can also enable expression images to be recognized as specific *** show that the protection success rate of our method is above 95%and the image quality evaluation degrades no more than *** quantitative and qualitative results show that our proposed method has a balance between privacy and usability.
In the background modeling, moving objects would often enter the scene. ＂Ghost＂ emerges as the pixels of interfering objects damage the background model. This paper presents a ＂ghost＂ suppression algorithm based o...
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In the background modeling, moving objects would often enter the scene. ＂Ghost＂ emerges as the pixels of interfering objects damage the background model. This paper presents a ＂ghost＂ suppression algorithm based on two - frame difference method and topology (TFDT). First in TFDT algorithm is to obtain the change mask with two-frame-difference method detecting the difference between two adjacent frames. Then according to the change mask, the complete object region and its bounding box are estimated with topo-logical structure. Finally, the pixels in the bounding box are eliminated, and the remaining pixels are added to the background model. TFDT is a universal algorithm for background modeling and can be adapted in foreground detection algorithms such as Codebook and ViBe. It can effectively remove object's pixels and build a background model for foreground detection algorithms. In this work, TFDT is used to improve Codebook and ViBe, and the ＂ghost＂ is absent from the result, which has been verfied in the CDnet database.
Oakes's argument shows that no statistical analysis, however complex, of sequential data can be guaranteed to provide asymptotically valid forecasts for every possible set of outcomes.
Oakes's argument shows that no statistical analysis, however complex, of sequential data can be guaranteed to provide asymptotically valid forecasts for every possible set of outcomes.
Escape time algorithm is an universal algorithm when creating fractal image.A class of algorithms based on escape time algorithm is *** this essay,combined with the feature of eventually periodic point of functions,we...
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Escape time algorithm is an universal algorithm when creating fractal image.A class of algorithms based on escape time algorithm is *** this essay,combined with the feature of eventually periodic point of functions,we define a class of points as no-escape *** analyze the shortcomings of the classic algorithm,we improve the escape time algorithm base on the no-escape *** analyze the algorithm and put forward the best application scope for *** creating fractal figures,we find figures created by the two algorithms are consistent with each other except a few escape *** compare the complexity between the two algorithms and find the iteration times by the improved algorithm are less than escape time algorithm when creating the fractal *** do several experiments and find the improved algorithm is universal and it reduces time wasting.
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