An odd hole in a graph is an induced cycle with odd length greater than 3. In an earlier paper (with Sophie Spirkl), solving a longstanding open problem, we gave a polynomial-time algorithm to test if a graph has an o...
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An odd hole in a graph is an induced cycle with odd length greater than 3. In an earlier paper (with Sophie Spirkl), solving a longstanding open problem, we gave a polynomial-time algorithm to test if a graph has an odd hole. We subsequently showed that, for every t, there is a polynomial-time algorithm to test whether a graph contains an odd hole of length at least t. In this article, we give an algorithm that finds a shortest odd hole, if one exists.
Exploiting geothermal resources such as hot dry rocks (HDRs) requires directional drilling technology. Measurement- while- drilling (MWD) technology plays a crucial role in directional measurement. However, its high t...
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Exploiting geothermal resources such as hot dry rocks (HDRs) requires directional drilling technology. Measurement- while- drilling (MWD) technology plays a crucial role in directional measurement. However, its high temperature and environment limit downhole measurement instruments in application. For this research, we designed an MWD system with a mechanical gravity tool face, and the fully mechanical structure was used to overcome the high- temperature constraints. The bias stabilization platform, gravity tool face coding method, and mud pulse generation structure were designed. The eccentric stable model and pulse generation structure model were established through numerical analysis, and a gravity tool face angle coding and identification method was also established. The experimental prototype testing system was built on theoretical analysis and hydrodynamics. The feasibility of the tool functions and the recognition algorithm were verified experimentally, with a maximum measurement error of 6 degrees and an average measurement error of 2.6 degrees. The average measurement error of the system in the well test is 6 degrees, which verifies the reliability of the system.
Raman spectroscopy has been increasingly researched this year. Due to the high accuracy, fast speed, and nondestructive detection features of Raman spectroscopy, there are more and more application scenarios. In this ...
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Raman spectroscopy has been increasingly researched this year. Due to the high accuracy, fast speed, and nondestructive detection features of Raman spectroscopy, there are more and more application scenarios. In this paper, a smart phone Raman system is studied. By the optical path design and slit coupling technology, the sensitivity of the device is improved while the size of the spectrometer itself is reduced. In order to improve the detection speed and accuracy, a cloud network architecture is proposed. The spectrometer is integrated into the backside of a smart phone and the wireless communication function of the smart phone can be used to realize the connection with the cloud server. The device terminal is only responsible for collecting and uploading data to the cloud. Spectra are identified by the algorithm server. The result and the attributes files are then transmitted to the smart Raman terminal. The algorithm, database, and terminal equipment are separated from each other to facilitate the timely update of algorithms and databases.
We introduce new versions of chordal and split digraphs, and explore their similarity with the corresponding undirected notions. (C) 2016 Elsevier B.V. All rights reserved.
We introduce new versions of chordal and split digraphs, and explore their similarity with the corresponding undirected notions. (C) 2016 Elsevier B.V. All rights reserved.
Ball sports have great variability in the game and the intelligent control of the rules of ball movement can effectively improve the training effect of athletes. However, the current research on artificial intelligenc...
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Ball sports have great variability in the game and the intelligent control of the rules of ball movement can effectively improve the training effect of athletes. However, the current research on artificial intelligence of spherical motion trajectory prediction points is basically blank. Based on this, this study is based on deep learning technology, and obtains the main experimental data through network data collection in the research and builds the table tennis spatial position image data set under various environments with accurate annotation based on the traditional deep learning. At the same time, the convolutional neural network is used as the location recognition algorithm, and a prediction algorithm for predicting the trajectory of table tennis is proposed based on the recurrent neural network. In addition, this paper designs comparative experiments to analyze the effectiveness of the algorithm model, and evaluates the real-time recognition, location and trajectory prediction capabilities, and conducts quantitative analysis. The research shows that the algorithm has certain practical effects and can provide theoretical reference for subsequent related research.
The paper in question deals with the invariant with respect to geometric deformations recognition algorithm of magnetocardiographic images in the framework of information-extreme intellectual technology based on maxim...
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The paper in question deals with the invariant with respect to geometric deformations recognition algorithm of magnetocardiographic images in the framework of information-extreme intellectual technology based on maximization of the information capacity of recognition system in the process of its learning.
Fibonacci strings are binary strings that contain no two consecutive 1s. The Fibonacci cube I" (h) is the subgraph of the h-cube induced by the Fibonacci strings. These graphs are applicable as interconnection ne...
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Fibonacci strings are binary strings that contain no two consecutive 1s. The Fibonacci cube I" (h) is the subgraph of the h-cube induced by the Fibonacci strings. These graphs are applicable as interconnection networks and in theoretical chemistry, and lead to the Fibonacci dimension of a graph. We derive a new characterization of Fibonacci cubes. The characterization is the basis for an algorithm which recognizes these graphs in linear time. Moreover, a graph which was recognized as a Fibonacci cube can be embedded into a hypercube using Fibonacci strings within the same time bound.
A graph G was defined in [16] as P-4-reducible, if no vertex in G belongs to more than one chordless path on four vertices or P-4. A graph G is defined in [15] as P-4-sparse if no set of five vertices induces more tha...
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A graph G was defined in [16] as P-4-reducible, if no vertex in G belongs to more than one chordless path on four vertices or P-4. A graph G is defined in [15] as P-4-sparse if no set of five vertices induces more than one P-4 in G. P-4-sparse graphs generalize both P-4-reducible and the well known class of P-4-free graphs or cographs. In an extended abstract in [11] the first author introduced a method using the modular decomposition tree of a graph as the framework for the resolution of algorithmic problems. This method was applied to the study of P-4-sparse and extended P-4-sparse graphs. In this paper, we begin by presenting the complete information about the method used in [11]. We propose a unique tree representation of P-4-sparse and a unique tree representation of P-4-reducible graphs leading to a simple linear recognition algorithm for both classes of graphs. In this way we simplify and unify the solutions for these problems, presented in [16-19]. The tree representation of an n-vertex P-4-sparse or a P-4-reducible graph is the key for obtaining O(n) time algorithms for the weighted version of classical optimization problems solved in [20]. These problems are NP-complete on general graphs. Finally, by relaxing the restriction concerning the exclusion of the C-5 cycles from P-4-sparse and P-4-reducible graphs, we introduce the class of the extended P-4-sparse and the class of the extended P-4-reducible graphs. We then show that a minimal amount of additional work suffices for extending most of our algorithms to these new classes of graphs.
In this paper, we study the class of graphs C defined by excluding the following structures as induced subgraphs: theta, pyramid, 1-wheel, and 3-wheel. We describe the structure of graphs in C, and we give a polynomia...
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In this paper, we study the class of graphs C defined by excluding the following structures as induced subgraphs: theta, pyramid, 1-wheel, and 3-wheel. We describe the structure of graphs in C, and we give a polynomial-time recognition algorithm for this class. We also prove that K4-free graphs in C are 4-colorable. We remark that C includes the class of chordal graphs, as well as the class of line graphs of triangle-free graphs.
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