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Wyszukujesz frazę "Hamiltonian" wg kryterium: Temat


Tytuł:
Quantum simulations of band-to-band tunnelling in a type-II broken-gap superlattice diode
Autorzy:
Makowiec, Marcin
Kolek, Andrzej
Powiązania:
https://bibliotekanauki.pl/articles/2204215.pdf
Data publikacji:
2023
Wydawca:
Polska Akademia Nauk. Stowarzyszenie Elektryków Polskich
Tematy:
type-II superlattice
broken-gap superlattice diode
band-to-band tunnelling
quantum transport
nonequilibrium Green’s function
twoband Hamiltonian
Opis:
In recent years, type-II superlattice-based devices have completed the offer of the electronic industry in many areas of applications. Photodetection is one of them, especially in the midinfrared wavelength range. It is due to the unique feature of a superlattice material, which is a tuneable bandgap. It is also believed that the dark current of superlattice-based photodetectors is strongly suppressed due to the suppression of the band-to-band tunnelling current in a superlattice material. This argument relies, however, on a semi-classical approach that treats superlattice as a bulk material with effective parameters extracted from the k·p analysis. In the paper, a superlattice device is analysed on a quantum level: the nonequilibrium Green’s function method is applied to the two-band Hamiltonian of the InAs/GaSb superlattice p-i-n diode. The analysis concentrates on the band-to-band tunnelling with the aim to validate the correctness of a semi-classical description of the phenomenon. The results of calculations reveal that in a superlattice diode, the inter-band tunnelling occurs only for certain values of energy and in-plane momentum, for which electronic and hole sub-bands cross. The transitions occurring for vanishing in-plane momentum produce resonances in the current-voltage characteristics - the feature which was reported in a few experimental observations. This scenario is quite different from that occurring in bulk materials, where there is a range of energy-momentum pairs for which the band-to-band tunnelling takes place, and so current-voltage characteristics are free from any resonances. However, simulations show that, while not justified for a detailed analysis, the semi-classical description can be applied to superlattice-based devices for an ‘order of magnitude’ estimation of the band-to-band tunnelling current.
Źródło:
Opto-Electronics Review; 2023, 31, Special Issue; art. no. e144558
1230-3402
Pojawia się w:
Opto-Electronics Review
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Hamiltonian Extendable Graphs
Autorzy:
Yang, Xiaojing
Xiong, Liming
Powiązania:
https://bibliotekanauki.pl/articles/32304150.pdf
Data publikacji:
2022-08-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
Hamiltonian extendable
forbidden subgraph
Opis:
A graph is called Hamiltonian extendable if there exists a Hamiltonian path between any two nonadjacent vertices. In this paper, we give an explicit formula of the minimum number of edges for Hamiltonian extendable graphs and we also characterize the degree sequence for Hamiltonian extendable graphs with minimum number of edges. Besides, we completely characterize the pairs of forbidden subgraphs for 2-connected graphs to be Hamiltonian extendable.
Źródło:
Discussiones Mathematicae Graph Theory; 2022, 42, 3; 843-859
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Nested Locally Hamiltonian Graphs and the Oberly-Sumner Conjecture
Autorzy:
de Wet, Johan P.
Frick, Marietjie
Powiązania:
https://bibliotekanauki.pl/articles/32222536.pdf
Data publikacji:
2022-11-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
locally traceable
locally hamiltonian
Hamilton Cycle Problem
locally k -nested-hamiltonian
Oberly-Sumner Conjecture
Opis:
A graph G is locally P, abbreviated L, if for every vertex v in G the open neighbourhood N(v) of v is non-empty and induces a graph with property P. Specifically, a graph G without isolated vertices is locally connected (LC) if N(v) induces a connected graph for each v ∈ V (G), and locally hamiltonian (LH) if N(v) induces a hamiltonian graph for each v ∈ V (G). A graph G is locally locally P (abbreviated L2P) if N(v) is non-empty and induces a locally P graph for every v ∈ V (G). This concept is generalized to an arbitrary degree of nesting. For any k ≥ 0 we call a graph locally k-nested-hamiltonian if it is LmC for m = 0, 1, . . ., k and LkH (with L0C and L0H meaning connected and hamiltonian, respectively). The class of locally k-nested-hamiltonian graphs contains important subclasses. For example, Skupień had already observed in 1963 that the class of connected LH graphs (which is the class of locally 1-nested-hamiltonian graphs) contains all triangulations of closed surfaces. We show that for any k ≥ 1 the class of locally k-nested-hamiltonian graphs contains all simple-clique (k + 2)-trees. In 1979 Oberly and Sumner proved that every connected K1,3-free graph that is locally connected is hamiltonian. They conjectured that for k ≥ 1, every connected K1,k+3-free graph that is locally (k + 1)-connected is hamiltonian. We show that locally k-nested-hamiltonian graphs are locally (k + 1)-connected and consider the weaker conjecture that every K1,k+3-free graph that is locally k-nested-hamiltonian is hamiltonian. We show that if our conjecture is true, it would be “best possible” in the sense that for every k ≥ 1 there exist K1,k+4-free locally k-nested-hamiltonian graphs that are non-hamiltonian. We also attempt to determine the minimum order of non-hamiltonian locally k-nested-hamiltonian graphs and investigate the complexity of the Hamilton Cycle Problem for locally k-nested-hamiltonian graphs with restricted maximum degree.
Źródło:
Discussiones Mathematicae Graph Theory; 2022, 42, 4; 1281-1312
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On Hamiltonian Cycles in Claw-Free Cubic Graphs
Autorzy:
Mohr, Elena
Rautenbach, Dieter
Powiązania:
https://bibliotekanauki.pl/articles/32361735.pdf
Data publikacji:
2022-02-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
Hamiltonian cycle
claw-free graph
cubic graph
Opis:
We show that every claw-free cubic graph of order $n$ at least 8 has at most $ 2\floor{ \frac{n}{4} } $ Hamiltonian cycles, and we also characterize all extremal graphs.
Źródło:
Discussiones Mathematicae Graph Theory; 2022, 42, 1; 309-313
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Predicting IoT failures with Bayesian workflow
Autorzy:
Baranowski, Jerzy
Powiązania:
https://bibliotekanauki.pl/articles/2087008.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Polskie Naukowo-Techniczne Towarzystwo Eksploatacyjne PAN
Tematy:
IoT failures
Bayesian workflow
post-stratification
Hamiltonian Monte Carlo
Opis:
IoT networks are so voluminous that they cannot be treated as individual devices, but as populations. Main aim of the paper is to create a comprehensive method for predicting failures taking device variance into consideration. We propose using data fusion of happenstance observations (resets and failures) to better estimate device parameters. We propose using methods of population analysis in Bayesian statistics to estimate failure times investigating only a part of the population. For this purpose, we use multilevel hierarchical Bayesian model and provide it with post stratification. We propose model assumptions, construct the model and evaluate it, and perform computations using Hamiltonian Monte Carlo. This method is known as the Bayesian workflow. We have analyzed three different models showing that, in case of small device variance, it can be ignored, or at least compensated, while significant differences require hierarchical modeling. We also show that hierarchical model shows significant robustness to a small amount of data. We have shown attractiveness of Bayesian approach to modeling failures of IoT devices. Ability to diagnose and tune models, and assure their computational fidelity is a great advantage of Bayesian workflow.
Źródło:
Eksploatacja i Niezawodność; 2022, 24, 2; 248--259
1507-2711
Pojawia się w:
Eksploatacja i Niezawodność
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Arc-Disjoint Hamiltonian Paths in Strong Round Decomposable Local Tournaments
Autorzy:
Meng, Wei
Powiązania:
https://bibliotekanauki.pl/articles/32083838.pdf
Data publikacji:
2021-02-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
local tournament
round-decomposable
arc-disjoint Hamiltonian paths
Opis:
Thomassen, [Edge-disjoint Hamiltonian paths and cycles in tournaments, J. Combin. Theory Ser. B 28 (1980) 142–163] proved that every strong tournament has a pair of arc-disjoint Hamiltonian paths with distinct initial vertices and distinct terminal vertices if and only if it is not an almost transitive tournament of odd order. As a subclass of local tournaments, Li et al. [Arc-disjoint Hamiltonian cycles in round decomposable local tournaments, Discuss. Math. Graph Theory 38 (2018) 477–490] confirmed the existence of such two paths in 2-strong round decomposable local tournaments. In this paper, we show that every strong, but not 2-strong, round decomposable local tournament contains a pair of arc-disjoint Hamiltonian paths with distinct initial vertices and distinct terminal vertices except for three classes of digraphs. Thus Thomassen's result is partly extended to round decomposable local tournaments. In addition, we also characterize strong round digraphs which contain a pair of arc-disjoint Hamiltonian paths with distinct initial vertices and distinct terminal vertices.
Źródło:
Discussiones Mathematicae Graph Theory; 2021, 41, 1; 297-310
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Hamiltonian Cycle Problem in Strong k-Quasi-Transitive Digraphs with Large Diameter
Autorzy:
Wang, Ruixia
Powiązania:
https://bibliotekanauki.pl/articles/32083906.pdf
Data publikacji:
2021-05-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
quasi-transitive digraph
k -quasi-transitive digraph
Hamiltonian cycle
Opis:
Let k be an integer with k ≥ 2. A digraph is k-quasi-transitive, if for any path x0x1... xk of length k, x0 and xk are adjacent. Let D be a strong k-quasi-transitive digraph with even k ≥ 4 and diameter at least k +2. It has been shown that D has a Hamiltonian path. However, the Hamiltonian cycle problem in D is still open. In this paper, we shall show that D may contain no Hamiltonian cycle with k ≥ 6 and give the sufficient condition for D to be Hamiltonian.
Źródło:
Discussiones Mathematicae Graph Theory; 2021, 41, 2; 685-690
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On optimal control problem subject to fractional order discrete time singular systems
Autorzy:
Chiranjeevi, Tirumalasetty
Biswas, Raj Kumar
Devarapalli, Ramesh
Babu, Naladi Ram
García Márquez, Fausto Pedro
Powiązania:
https://bibliotekanauki.pl/articles/2083465.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
fractional optimal control problem
discrete time singular system
fractional derivative
Hamiltonian technique
Opis:
In this work, we present optimal control formulation and numerical algorithm for fractional order discrete time singular system (DTSS) for fixed terminal state and fixed terminal time endpoint condition. The performance index (PI) is in quadratic form, and the system dynamics is in the sense of Riemann-Liouville fractional derivative (RLFD). A coordinate transformation is used to convert the fractional-order DTSS into its equivalent non-singular form, and then the optimal control problem (OCP) is formulated. The Hamiltonian technique is used to derive the necessary conditions. A solution algorithm is presented for solving the OCP. To validate the formulation and the solution algorithm, an example for fixed terminal state and fixed terminal time case is presented.
Źródło:
Archives of Control Sciences; 2021, 31, 4; 849-863
1230-2384
Pojawia się w:
Archives of Control Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
2-Connected Hamiltonian Claw-Free Graphs Involving Degree Sum of Adjacent Vertices
Autorzy:
Tian, Tao
Xiong, Liming
Powiązania:
https://bibliotekanauki.pl/articles/32034090.pdf
Data publikacji:
2020-02-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
Hamiltonian cycle
degree sum
dominating closed trail
closure
Opis:
For a graph H, define $\overline{\sigma}_2(H)=min\{d(u)+d(v)|uv∈E(H)\}$. Let $H$ be a 2-connected claw-free simple graph of order $n$ with \(\delta(H) ≥ 3\). In [J. Graph Theory 86 (2017) 193–212], Chen proved that if $\overline{\sigma}_2(H)≥\frac{n}{2}−1$ and $n$ is sufficiently large, then $H$ is Hamiltonian with two families of exceptions. In this paper, we refine the result. We focus on the condition $\overline{\sigma}_2(H)≥\frac{2n}{5}−1$, and characterize non-Hamiltonian 2-connected claw-free graphs $H$ of order $n$ sufficiently large with $\overline{\sigma}_2(H)≥\frac{2n}{5}−1$. As byproducts, we prove that there are exactly six graphs in the family of 2-edge-connected triangle-free graphs of order at most seven that have no spanning closed trail and give an improvement of a result of Veldman in [Discrete Math. 124 (1994) 229–239].
Źródło:
Discussiones Mathematicae Graph Theory; 2020, 40, 1; 85-106
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A Note on Cycles in Locally Hamiltonian and Locally Hamilton-Connected Graphs
Autorzy:
Tang, Long
Vumar, Elkin
Powiązania:
https://bibliotekanauki.pl/articles/32032199.pdf
Data publikacji:
2020-02-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
locally connected
locally Hamiltonian
locally Hamilton-connected
fully cycle extendability
weakly pancyclicity
Opis:
Let \(\mathcal{P}\) be a property of a graph. A graph G is said to be locally \(\mathcal{P}\), if the subgraph induced by the open neighbourhood of every vertex in G has property \(\mathcal{P}\). Ryjáček conjectures that every connected, locally connected graph is weakly pancyclic. Motivated by the above conjecture, van Aardt et al. [S.A.van Aardt, M. Frick, O.R. Oellermann and J.P.de Wet, Global cycle properties in locally connected, locally traceable and locally Hamiltonian graphs, Discrete Appl. Math. 205 (2016) 171–179] investigated the global cycle structures in connected, locally traceable/Hamiltonian graphs. Among other results, they proved that a connected, locally Hamiltonian graph G with maximum degree at least |V (G)| − 5 is weakly pancyclic. In this note, we improve this result by showing that such a graph with maximum degree at least |V (G)|−6 is weakly pancyclic. Furthermore, we show that a connected, locally Hamilton-connected graph with maximum degree at most 7 is fully cycle extendable.
Źródło:
Discussiones Mathematicae Graph Theory; 2020, 40, 1; 77-84
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Decomposing the Complete Graph Into Hamiltonian Paths (Cycles) and 3-Stars
Autorzy:
Lee, Hung-Chih
Chen, Zhen-Chun
Powiązania:
https://bibliotekanauki.pl/articles/31521539.pdf
Data publikacji:
2020-08-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
decomposition
complete graph
Hamiltonian path
Hamiltonian cycle
star
Opis:
Let H be a graph. A decomposition of H is a set of edge-disjoint subgraphs of H whose union is H. A Hamiltonian path (respectively, cycle) of H is a path (respectively, cycle) that contains every vertex of H exactly once. A k-star, denoted by Sk, is a star with k edges. In this paper, we give necessary and sufficient conditions for decomposing the complete graph into α copies of Hamiltonian path (cycle) and β copies of S3.
Źródło:
Discussiones Mathematicae Graph Theory; 2020, 40, 3; 823-839
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Lower Bound on the Number of Hamiltonian Cycles of Generalized Petersen Graphs
Autorzy:
Lu, Weihua
Yang, Chao
Ren, Han
Powiązania:
https://bibliotekanauki.pl/articles/32083755.pdf
Data publikacji:
2020-02-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
generalized Petersen graph
Hamiltonian cycle
partition number
1-factor
Opis:
In this paper, we investigate the number of Hamiltonian cycles of a generalized Petersen graph $ P(N, k) $ and prove that $ \Psi(P(N,3)) \ge N \cdot \alpha_N $, where $ \Psi (P(N, 3)) $ is the number of Hamiltonian cycles of $P(N, 3)$ and $ \alpha_N $ satisfies that for any $ \epsilon > 0 $, there exists a positive integer $M$ such that when $ N > M $, $ ((1− \epsilon ) \frac{ (1−r^3) }{6r^3+5r^2+3) }( 1/r )^{N+2} < \alpha_N < ( (1+ɛ) \frac{ (1−r^3) }{6r^3+5r^2+3) }( 1/r )^{N+2} $, where $ 1/r = \text{max} \{ | \frac{1}{r_j} | : j=1,2,…,6 \} $, and each $ r_j $ is a root of equation $ x^6 + x^5 + x^3 − 1 = 0 $, $ r \approx 0.782 $. This shows that $ \Psi (P (N, 3) $ is exponential in $N$ and also deduces that the number of 1-factors of $ P(N, 3)$ is exponential in $N$.
Źródło:
Discussiones Mathematicae Graph Theory; 2020, 40, 1; 297-305
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On Factorable Bigraphic Pairs
Autorzy:
Yin, Jian-Hua
Li, Sha-Sha
Powiązania:
https://bibliotekanauki.pl/articles/31515537.pdf
Data publikacji:
2020-08-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
degree sequence
bigraphic pair
Hamiltonian cycle
Opis:
Let $S = (a_1,. . ., a_m; b_1, . . ., b_n)$, where $a_1, . . ., a_m$ and $b_1, . . ., b_n$ are two sequences of nonnegative integers. We say that $S$ is a bigraphic pair if there exists a simple bipartite graph $G$ with partite sets ${x_1, x_2, . . ., x_m}$ and ${y_1, y_2, . . ., y_n}$ such that $d_G(x_i) = a_i$ for $1 ≤ i ≤ m$ and $d_G(y_j) = b_j$ for $1 ≤ j ≤ n$. In this case, we say that $G$ is a realization of $S$. Analogous to Kundu’s $k$-factor theorem, we show that if $(a_1, a_2, . . ., a_m; b_1, b_2, . . ., b_n)$ and $(a_1 − e_1, a_2 − e_2, . . ., a_m − e_m; b_1 − f_1, b_2 − f_2, . . ., b_n − f_n)$ are two bigraphic pairs satisfying $k ≤ f_i ≤ k + 1, 1 ≤ i ≤ n$ (or$ k ≤ e_i ≤ k + 1, 1 ≤ i ≤ m$), for some $0 ≤ k ≤ m − 1$ (or $0 ≤ k ≤ n − 1$), then $(a_1, a_2, . . ., a_m; b_1, b_2, . . ., b_n)$ has a realization containing an $(e_1, e_2, . . ., e_m; f_1, f_2, . . ., f_n)$-factor. For $m = n$, we also give a necessary and sufficient condition for an $(k^n; k^n)$-factorable bigraphic pair to be connected $(k^n; k^n)$-factorable when $k ≥ 2$. This implies a characterization of bigraphic pairs with a realization containing a Hamiltonian cycle.
Źródło:
Discussiones Mathematicae Graph Theory; 2020, 40, 3; 787-793
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Some multiplicity results of homoclinic solutions for second order Hamiltonian systems
Autorzy:
Barile, Sara
Salvadore, Addolorata
Powiązania:
https://bibliotekanauki.pl/articles/255922.pdf
Data publikacji:
2020
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
second order Hamiltonian systems homoclinic solutions
variational methods
compact embeddings
Opis:
We look for homoclinic solutions [formula] to the class of second order Hamiltonian systems [formula] where [formula] and a, b : R → R are positive bounded functions, [formula] are positive homogeneous functions and [formula]. Using variational techniques and the Pohozaev fibering method, we prove the existence of infinitely many solutions if = 0 and the existence of at least three solutions if ƒ is not trivial but small enough.
Źródło:
Opuscula Mathematica; 2020, 40, 1; 21-36
1232-9274
2300-6919
Pojawia się w:
Opuscula Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spectral Conditions for Graphs to be k-Hamiltonian or k-Path-Coverable
Autorzy:
Liu, Weijun
Liu, Minmin
Zhang, Pengli
Feng, Lihua
Powiązania:
https://bibliotekanauki.pl/articles/32083834.pdf
Data publikacji:
2020-02-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
spectral radius
minimum degree
k -Hamiltonian
k -path-coverable
Opis:
A graph G is k-Hamiltonian if for all X ⊂ V (G) with |X| ≤ k, the subgraph induced by V (G) \ X is Hamiltonian. A graph G is k-path-coverable if V (G) can be covered by k or fewer vertex disjoint paths. In this paper, by making use of the vertex degree sequence and an appropriate closure concept (due to Bondy and Chvátal), we present sufficient spectral conditions of a connected graph with fixed minimum degree and large order to be k-Hamiltonian or k-path-coverable.
Źródło:
Discussiones Mathematicae Graph Theory; 2020, 40, 1; 161-179
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł

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