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pro vyhledávání: '"LYU Zhenhua"'
Publikováno v:
Zhejiang dianli, Vol 43, Iss 11, Pp 26-35 (2024)
Wind turbines can contribute to frequency regulation by releasing rotor kinetic energy， which is an effective way to ensure frequency stability in power systems with high wind power penetration. However， the rotor speed recovery process may cause
Externí odkaz:
https://doaj.org/article/ea70c109cce64948a29bbb44eb50f4d3
Autor:
Lyu Zhenhua
Publikováno v:
Discussiones Mathematicae Graph Theory, Vol 42, Iss 3, Pp 985-1004 (2022)
Let n ≥ 8 be an integer. We characterize the extremal digraphs of order n with the maximum number of arcs avoiding distinct walks of length 4 with the same endpoints.
Externí odkaz:
https://doaj.org/article/a0e91e51dca34d1bb2d6693477da5e3f
Autor:
Huang, Zejun, Lyu, Zhenhua
Given a positive integer $t$, let $P_{t,2}$ be the digraph consisting of $t$ directed paths of length 2 with the same initial and terminal vertices. In this paper, we study the maximum size of $P_{t+1,2}$-free digraphs of order $n$, which is denoted
Externí odkaz:
http://arxiv.org/abs/2406.16101
Autor:
Lyu, Zhenhua
Let $n,k,t$ be positive integers. What is the maximum number of arcs in a digraph on $n$ vertices in which there are at most $t$ distinct walks of length $k$ with the same endpoints? In this paper, we prove that the maximum number is equal to $n(n-1)
Externí odkaz:
http://arxiv.org/abs/2106.00212
Autor:
Huang, Zejun, Lyu, Zhenhua
In this paper, we determine the maximum size of digraphs on $n$ vertices in which there are no two distinct walks of length $3$ with the same initial vertex and the same terminal vertex. The digraphs attaining this maximum size are also characterized
Externí odkaz:
http://arxiv.org/abs/2104.08498
Akademický článek
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Autor:
Huang, Zejun, Lyu, Zhenhua
In this paper, we determine the maximum number of nonzero entries in 0-1 matrices of order $n$ with zero trace whose squares are 0-1 matrices when $n\ge 8$. The extremal matrices attaining this maximum number are also characterized.
Comment: 20
Comment: 20
Externí odkaz:
http://arxiv.org/abs/1803.01293
Autor:
Huang, Zejun, Lyu, Zhenhua
Let $P_{2,2}$ be the orientation of $C_4$ which consists of two 2-paths with the same initial and terminal vertices. In this paper, we determine the maximum size of $P_{2,2}$-free digraphs of order $n$ as well as the extremal digraphs attaining the m
Externí odkaz:
http://arxiv.org/abs/1802.03431
Publikováno v:
Mathematical Methods in the Applied Sciences; Dec2024, Vol. 47 Issue 18, p14718-14726, 9p