A polygonP is said to be apalm polygon if there exists a pointxP such that the Euclidean shortest path fromx to any pointyP makes only left turns or only right turns. The set of all such pointsx is called thepalm kernel. In this paper we propose an O(E) time algorithm for recognizing a palm polygonP, whereE is the size of the visibility graph ofP. The algorithm recognizes the given polygonP as a palm polygon by computing the palm kernel ofP. If the palm kernel is not empty,P is a palm polygon.The extended abstract of this paper was reported at the Second Canadian Conference in Computational Geometry, pp. 246–251, 1990 相似文献
The role of the vertebral arteries in delaying loss of sensibility following neck sticking in slaughter calves was investigated. Vertebral artery blood flow was measured using probes before, during and after electrical stunning and slaughter. Systemic blood pressure, electrocorticogram, visually evoked responses and the occurrence of carotid occlusions were also recorded. When carotid occlusion occurred, the time to onset of brain failure was delayed based on the development of an isoelectric state. In addition, when carotid occlusion occurred the mean arterial blood pressure was sustained for longer following slaughter, and concurrently vertebral artery blood flow could be maintained at about 30% of its initial level for up to 3 min. In some animals vertebral artery flow increased substantially following sticking. When chest sticking was used no occlusion of vessels occurred, mean arterial blood pressure fell promptly (within 8 s) and the onset of an isoelectric state did not extend beyond one minute. In addition, visually evoked responses were not present after 5 s following chest sticking. 相似文献
The use of rechargeable sensors is a promising solution for wireless sensor networks. On this type of network, mobile charging vehicles (MC) are used for charging sensors using wireless energy transfer (WET) technology. In on-demand charging, a sensor transmits a charging request to the service station, and the MC visits the sensor to transfer energy. The key disadvantages of utilizing MC-based WET are its high energy expenditure rate due to mobility, long service time, and slow charging rate. Because of these reasons, sensors deplete their energy and become dead before the MC reaches the requesting nodes to recharge. We have adapted a genetic algorithm-based partial charging scheme to serve the charging requests. Our objective is to improve the survival ratio of the network. Using comprehensive simulations, we analyze the performance of our proposed method and compare it to two other existing approaches. The simulation results demonstrate that our proposed algorithm improves the survival ratio by up to 20 % by developing a dynamic energy threshold function for transmitting charging requests from the sensors and a partial charging schedule using a genetic algorithm. 相似文献
An Orthogonal frequency part multiplexing suffers from a considerable challenge due to a high peak to average power ratio (PAPR). Hence, an effective method such as partial transmits sequence (PTS) can avert this defiance by limit the design of PAPR. Therefore, an improving PAPR reduction performance via a novel approach is proposed by detaching each subblock into two parts furthermore exchanges the first sample with the final selection in each portion of the subblock to generate a new partitioning scheme. Several typical traditional segmentation schemes are used to analyze and apply the presented algorithm, such as adjacent, interleaving, and pseudo-random schemes. Besides, two scenarios are adopted based on simulation software in which the number of subcarriers is set to 128 and 256. Based on the results, a superior PAPR reduction performance is achieved based on the improved segmentation schemes regarding traditional strategies in both systems. Moreover, the enhanced adjusted PTS scheme poses a low computational complexity compared with that of the conventional schemes.
A denoising procedure is proposed to remove both out-band and in-band noise for extraction of weak bursts in signal obtained from defective bearing. Energy of continuous wavelet scalogram is computed and the band having higher energy is selected to remove the out-band noise. Signals of selected band are brought together to form a high-dimensional waveform feature space. Further, low dimensional waveform manifold is formed using linear local tangent space alignment (LLTSA) algorithm to remove in-band noise. A criterion, entitled as frequency factor is also proposed to determine the optimum neighbour size of LLTSA. The two complicated conditions are chosen to demonstrate the effectiveness of the technique in the extraction of bursts in the noisy situations. A significant improvement in the signal to noise ratio is observed when in-band noise is removed using manifold learning by LLTSA algorithm. The experimental result reveals the success of the proposed denoising procedure in extraction of defect features, even in the case of noisy condition. 相似文献
Films of indium selenide was deposited onto glass and indium tin oxide coated glass substrates in acidic medium using chemical bath deposition at room temperature. Indium sulphate and sodium selenosulphate were used as precursors of In3+ and Se2?, respectively. The structural, surface morphological and optical properties of the deposited films were studied. Diffractograms in structural study revealed the deposited material is In2Se3 films. Controlled bath conditions resulted in the evolution of the In2Se3 microrod-like morphology. The optical band gap of the film was found to be 1.7 eV. 相似文献
A class of recursive functionsC islimiting standardizable, in a programming system , iff there is an effective procedure which, given any -program (in the -system), synthesizes in the limit acanonical -program which is equivalent to the former. It can arguably be expected that notions similar to the above one would be relevant toGold-style function learning, which features, among other things, the effective limiting synthesis of programs for input recursive functions. Many learning classes have been characterized in terms of variants of the above notion. In this paper, we focus on the limiting standardizability of the entire class of recursive functions inEffective programming systems. To start with, we prove the independence of this notionvis-à-vis finitary recursion theorems. Secondly, we show that this motion does not entail acceptability, in the spirit of the results of Case, Riccardi and Royer on characterizations of the samevis-à-vis programming language control structures. 相似文献
This paper proposes hybrid classification models and preprocessing methods for enhancing the consonant-vowel (CV) recognition
in the presence of background noise. Background Noise is one of the major degradation in real-time environments which strongly
effects the performance of speech recognition system. In this work, combined temporal and spectral processing (TSP) methods
are explored for preprocessing to improve CV recognition performance. Proposed CV recognition method is carried out in two
levels to reduce the similarity among large number of CV classes. In the first level vowel category of CV unit will be recognized,
and in the second level consonant category will be recognized. At each level complementary evidences from hybrid models consisting
of support vector machine (SVM) and hidden Markov models (HMM) are combined for enhancing the recognition performance. Performance
of the proposed CV recognition system is evaluated on Telugu broadcast database for white and vehicle noise. The proposed
preprocessing methods and hybrid classification models have improved the recognition performance compared to existed methods. 相似文献
We present polylogarithmic approximations for the R|prec|Cmax and R|prec|∑jwjCj problems, when the precedence constraints are “treelike”—i.e., when the undirected graph underlying the precedences is a
forest. These are the first non-trivial generalizations of the job shop scheduling problem to scheduling with precedence constraints
that are not just chains. These are also the first non-trivial results for the weighted completion time objective on unrelated
machines with precedence constraints of any kind. We obtain improved bounds for the weighted completion time and flow time for the case of chains with restricted assignment—this
generalizes the job shop problem to these objective functions. We use the same lower bound of “congestion + dilation”, as
in other job shop scheduling approaches (e.g. Shmoys, Stein and Wein, SIAM J. Comput. 23, 617–632, 1994). The first step in our algorithm for the R|prec|Cmax problem with treelike precedences involves using the algorithm of Lenstra, Shmoys and Tardos to obtain a processor assignment
with the congestion + dilation value within a constant factor of the optimal. We then show how to generalize the random-delays
technique of Leighton, Maggs and Rao to the case of trees. For the special case of chains, we show a dependent rounding technique
which leads to a bicriteria approximation algorithm for minimizing the flow time, a notoriously hard objective function.
A preliminary version of this paper appeared in the Proc. International Workshop on Approximation Algorithms for Combinatorial Optimization Problems (APPROX), pages 146–157, 2005.
V.S. Anil Kumar supported in part by NSF Award CNS-0626964. Part of this work was done while at the Los Alamos National Laboratory,
and supported in part by the Department of Energy under Contract W-7405-ENG-36.
M.V. Marathe supported in part by NSF Award CNS-0626964. Part of this work was done while at the Los Alamos National Laboratory,
and supported in part by the Department of Energy under Contract W-7405-ENG-36.
Part of this work by S. Parthasarathy was done while at the Department of Computer Science, University of Maryland, College
Park, MD 20742, and in part while visiting the Los Alamos National Laboratory. Research supported in part by NSF Award CCR-0208005
and NSF ITR Award CNS-0426683.
Research of A. Srinivasan supported in part by NSF Award CCR-0208005, NSF ITR Award CNS-0426683, and NSF Award CNS-0626636. 相似文献