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- 저자 : Zhanjun Chen (검색결과 5 건)
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LOCAL AND MEAN k-RAMSEY NUMBERS FOR THE FAMILY OF GRAPHS
Zhanjun Su,Hongjing Chen,Ren Ding 한국전산응용수학회 2009 Journal of applied mathematics & informatics Vol.27 No.3
For a family of graphs H and an integer k, we denote by Rk(H) the corresponding k-Ramsey number, which is defined to be the smallest integer n such that every k-coloring of the edges of Kn contains a monochromatic copy of a graph in H. The local k- Ramsey number Rk loc(H) and the mean k-Ramsey number Rk mean(H) are defined analogously. Let G be the family of non-bipartite graphs and Tn be the family of all trees on n vertices. In this paper we prove that Rk loc(G) =Rk mean(G), and R2(T n) < R2 loc(T n) = R2 mean(T n) for all ≥ 3. For a family of graphs H and an integer k, we denote by Rk(H) the corresponding k-Ramsey number, which is defined to be the smallest integer n such that every k-coloring of the edges of Kn contains a monochromatic copy of a graph in H. The local k- Ramsey number Rk loc(H) and the mean k-Ramsey number Rk mean(H) are defined analogously. Let G be the family of non-bipartite graphs and Tn be the family of all trees on n vertices. In this paper we prove that Rk loc(G) =Rk mean(G), and R2(T n) < R2 loc(T n) = R2 mean(T n) for all ≥ 3.
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LOCAL AND MEAN k-RAMSEY NUMBERS FOR THE FAMILY OF GRAPHS
Su, Zhanjun,Chen, Hongjing,Ding, Ren The Korean Society for Computational and Applied M 2009 Journal of applied mathematics & informatics Vol.27 No.3
For a family of graphs $\mathcal{H}$ and an integer k, we denote by $R^k(\mathcal{H})$ the corresponding k-Ramsey number, which is defined to be the smallest integer n such that every k-coloring of the edges of $K_n$ contains a monochromatic copy of a graph in $\mathcal{H}$. The local k-Ramsey number $R^k_{loc}(\mathcal{H})$ and the mean k-Ramsey number $R^k_{mean}(\mathcal{H})$ are defined analogously. Let $\mathcal{G}$ be the family of non-bipartite graphs and $T_n$ be the family of all trees on n vertices. In this paper we prove that $R^k_{loc}(\mathcal{G})=R^k_{mean}(\mathcal{G})$, and $R^2(T_n)$ < $R^2_{loc}(T_n)4 = $R^2_{mean}(T_n)$ for all $n\;{\ge}\;3$.
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Jilin Hu,Qizhong Huang,Hongxia Peng,Xiuying Tian,Zhanjun Chen,Yangxi Peng 한양대학교 세라믹연구소 2018 Journal of Ceramic Processing Research Vol.19 No.3
Aluminium oxide (Al2O3)-aluminium nitride (AlN) composites were prepared at 1500-1600 oC by pressureless sintering. Themain raw materials used were AlN and Al2O3, and appropriate amounts of TiO2-Y2O3-CaO-La2O3 quaternary sintering aidswere added. The effects of different AlN contents and sintering temperatures on the bulk density, bending strength, Rockwellhardness, thermal conductivity, and other properties of Al2O3-based ceramics were studied. The phase composition andmicrostructure of the samples were analysed with an X-ray diffractometer and scanning electron microscope. Results showedthat the Al2O3-AlN composites had excellent overall performance in terms of a flexural strength of 295.7MPa, a Rockwellhardness of 61.5 HRA, and a thermal conductivity of 38.8W/(m·K) (at 25 oC) after pressureless sintering at 1600 oC for 3 hwith 10 wt% AlN content. These properties met the requirements of high-power ceramic LED lamp holders. The Al2O3-10 wt%AlN composites sintered at 1600 oC had a dense microstructure, tight bonding among grains, and few pores, whichexplained the excellent performance of the samples.
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Yu Cao,Ruyi Deng,Jilin Hu,Jinxiu He,Dapeng Lei,Zhanjun Chen,Yangxi Peng 한양대학교 청정에너지연구소 2023 Journal of Ceramic Processing Research Vol.24 No.2
SiC-B4C composite powders were synthesized by the carbothermal reduction method under an argon atmosphere usingdifferent kinds of carbon sources (carbon black and starch) and silica sol and boric acid as the precursor raw materials. Basedon thermodynamic analysis and calculation, the effects of different carbon sources and reaction temperatures on the mass lossrate, phase composition, and microstructure of SiC-B4C ultrafine composite powders were comparatively studied. Resultsshowed that the optimum conditions for synthesizing SiC-B4C composite powders with carbon black as the carbon source were1550 ºC for 2 h, whereas the optimum conditions for synthesizing SiC-B4C composite powders with starch as the carbon sourcewere 1450 ºC-1550 ºC for 2 h. The powder samples synthesized with carbon black as the carbon source at 1550 ºC were mainlycomposed of flaky, columnar-like, spherical, and irregular polyhedral particles (about 100-200 nm in diameter). Mutualcohesion or agglomeration between particles was minimal. In the powder samples synthesized at 1550 ºC with an excess of 10wt% starch, in addition to a certain amount of flaky, spherical, and other irregular structure particles, a certain amount ofuniform, slender whiskers (about 50-100 nm in diameter) and a certain phenomenon of lap and winding between the whiskerswere noted. The powder samples synthesized at 1550 ºC with an excess of 20 wt% starch had no whisker-like substance.
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Zhan, Jun,Tang, Xiaohu,Chen, Qingchun Korean Society for Internet Information 2018 KSII Transactions on Internet and Information Syst Vol.12 No.8
In this paper, we investigate a buffer-aided wireless powered cooperative communication network (WPCCN), in which the source and relay harvest the energy from a dedicated power beacon via wireless energy transfer, then the source transmits the data to the destination through the relay. Both the source and relay are equipped with an energy buffer to store the harvested energy in the energy transfer stage. In addition, the relay is equipped with a data buffer and can temporarily store the received information. Considering the buffer-aided WPCCN, we propose two buffer-aided relaying protocols, which named as the buffer-aided harvest-then-transmit (HtT) protocol and the buffer-aided joint mode selection and power allocation (JMSPA) protocol, respectively. For the buffer-aided HtT protocol, the time-averaged achievable rate is obtained in closed form. For the buffer-aided JMSPA protocol, the optimal adaptive mode selection scheme and power allocation scheme, which jointly maximize the time-averaged throughput of system, are obtained by employing the Lyapunov optimization theory. Furthermore, we drive the theoretical bounds on the time-averaged achievable rate and time-averaged delay, then present the throughput-delay tradeoff achieved by the joint JMSPA protocol. Simulation results validate the throughput performance gain of the proposed buffer-aided relaying protocols and verify the theoretical analysis.
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