The directed vertex leafage of a chordal graph G is the smallest integer k such that G is the intersection graph of subtrees of a rooted directed tree where each subtree has at most k leaves. In this note, we show how...
详细信息
This paper presents the development and evaluation of two linear algorithms for forecasting reception power for different channels at an assigned spectrum band of global systems for mobile communications (GSM), in ord...
详细信息
This paper presents the development and evaluation of two linear algorithms for forecasting reception power for different channels at an assigned spectrum band of global systems for mobile communications (GSM), in order to analyze the spatial opportunity for reuse of frequencies by secondary users (SUs) in a cognitive radio (CR) network. The algorithms employed correspond to seasonal autoregressive integrated moving average (SARIMA) and generalized autoregressive conditional heteroskedasticity (GARCH), which allow for a forecast of channel occupancy status. Results are evaluated using the following criteria: availability and occupancy time for channels, different types of mean absolute error, and observation time. The contributions of this work include a more integral forecast as the algorithm not only forecasts reception power but also the occupancy and availability time of a channel to determine its precision percentage during the use by primary users (PUs) and SUs within a CR system. Algorithm analyses demonstrate a better performance for SARIMA over GARCH algorithm in most of the evaluated variables.
In this paper a traditional approach in system identification is adopted to design linear algorithms for H ∞ identification. That is to get the required algorithm by minimizing a tractable cost function which is care...
详细信息
In this paper a traditional approach in system identification is adopted to design linear algorithms for H ∞ identification. That is to get the required algorithm by minimizing a tractable cost function which is carefully constructed to measure the performance of all alternatives. By means of this approach, desirable linear convergent algorithms for H ∞ identification with observations in both frequency domain and time domain are presented. The new algorithms are not only very simple in computation, but can also deliver a tight upper bound on the worst-case identification error.
In this study, linear and tree-based algorithms were utilized to train the hydrogen-assisted fatigue crack growth test data. Through accuracy verification, it was found that the Gradient Boosting Regression (GB) belon...
详细信息
In this study, linear and tree-based algorithms were utilized to train the hydrogen-assisted fatigue crack growth test data. Through accuracy verification, it was found that the Gradient Boosting Regression (GB) belonging to tree-based algorithms had the best predictive performance. For the model trained by the GB algorithm, SHapley Additive exPlanations (SHAP) values were employed to evaluate the impact of stress intensity factor range, hydrogen pressure, ultimate tensile strength, stress ratio, frequency and chemical compositions on the hydrogenassisted fatigue crack growth. The results show that material properties, experimental conditions and environment all have an effect on the crack growth rate. Besides, the feature influence patterns derived from machine learning models are consistent with the literature, demonstrating that the model has the potential to accurately predict the hydrogen-assisted fatigue crack growth rate of Cr-Mo steel.
Quite often, real-life applications suggest the study of graphs that feature some local density properties. In particular, graphs that are unlikely to have more than a few chordless paths of length three appear in a n...
详细信息
Quite often, real-life applications suggest the study of graphs that feature some local density properties. In particular, graphs that are unlikely to have more than a few chordless paths of length three appear in a number of contexts. A graph G is P-4-sparse if no set of five vertices in G induces more than one chordless path of length three. P-4-sparse graphs generalize both the class of cographs and the class of P-4-reducible graphs. It has been shown that P-4-sparse graphs can be recognized in time linear in the size of the graph. The main contribution of this paper is to show that once the data structures returned by the recognition algorithm are in place, a number of NP-hard problems on general graphs can be solved in linear time for P-4-sparse graphs. Specifically with an n-vertex P-4-sparse graph as input the problems of finding a maximum size clique, maximum size stable set, a minimum coloring, a minimum covering by clique, and the size of the minimum fill-in can be solved in O(n) time, independent of the number of edges in the graph.
In the framework of Zhuravlev's algebraic approach to classification problems, a linear model of algorithms is investigated (estimates of class membership are generated by linear regressions). The possibility of w...
详细信息
In the framework of Zhuravlev's algebraic approach to classification problems, a linear model of algorithms is investigated (estimates of class membership are generated by linear regressions). The possibility of weakening the completeness requirement (obtaining an arbitrary estimation matrix) in order to obtain any classification of a fixed set of objects by using special decision rules is investigated.
In this study a new algorithm is proposed for distributed blind sensor macro-calibration in networked control systems robust to noise. The proposed distributed algorithm for estimation of gain and offset correction pa...
详细信息
In this study a new algorithm is proposed for distributed blind sensor macro-calibration in networked control systems robust to noise. The proposed distributed algorithm for estimation of gain and offset correction parameters is of stochastic approximation type, with local non-linear transformations of residuals. Convergence of the algorithm in mean-square and with probability one to consensus is proved for a large class of non-linear transformations, network properties and communication and measurement noise characteristics. The choice of the introduced non-linear transformations in accordance with the theory of robust statistics leads to the proposal of new calibration algorithms robustified w.r.t. noise. It is demonstrated by Monte Carlo simulation that the proposed algorithms are very efficient in the presence of large outliers from the point of view of both achievement of high convergence rate and adequate values of convergence points, outperforming the existing linear algorithms.
By identifying a local property which structurally classifies any edge, we show that the family of generalized Petersen graphs can be recognized in linear time. (C) 2020 Elsevier B.V. All rights reserved.
By identifying a local property which structurally classifies any edge, we show that the family of generalized Petersen graphs can be recognized in linear time. (C) 2020 Elsevier B.V. All rights reserved.
Cographs are the graphs formed from a single vertex under the closure of the operations of union and complement. Another characterization of cographs is that they are the undirected graphs with no induced paths on fou...
详细信息
Cographs are the graphs formed from a single vertex under the closure of the operations of union and complement. Another characterization of cographs is that they are the undirected graphs with no induced paths on four vertices. Cographs arise naturally in such application areas as examination scheduling and automatic clustering of index terms. Furthermore, it is known that cographs have a unique tree representation called a cotree. Using the cotree it is possible to design very fast polynomial time algorithms for problems which are intractable for graphs in general. Such problems include chromatic number, clique determination, clustering, minimum weight domination, isomorphism, minimum fill-in and Hamiltonicity. In this paper we present a linear time algorithm for recognizing cographs and constructing their cotree representation.
Space-time block coding (STBC) offers a good performance/complexity trade-off to exploit spatial diversity in multi-antenna systems. A particular linear precoder and the Alamouti STBC are combined to improve the space...
详细信息
Space-time block coding (STBC) offers a good performance/complexity trade-off to exploit spatial diversity in multi-antenna systems. A particular linear precoder and the Alamouti STBC are combined to improve the space-time diversity using simple linear algorithms. The system presented with four-transmit antennas may be applied to other STBC codes and several antenna configurations.
暂无评论