TREES WITH EQUAL STRONG ROMAN DOMINATION NUMBER AND ROMAN DOMINATION NUMBER

Chen, Xue-Gang,Sohn, Moo Young Korean Mathematical Society 2019 대한수학회보 Vol.56 No.1

A graph theoretical model called Roman domination in graphs originates from the historical background that any undefended place (with no legions) of the Roman Empire must be protected by a stronger neighbor place (having two legions). It is applicable to military and commercial decision-making problems. A Roman dominating function for a graph G = (V, E) is a function $f:V{\rightarrow}\{0,1,2\}$ such that every vertex v with f(v)=0 has at least a neighbor w in G for which f(w)=2. The Roman domination number of a graph is the minimum weight ${\sum}_{v{\in}V}\;f(v)$ of a Roman dominating function. In order to deal a problem of a Roman domination-type defensive strategy under multiple simultaneous attacks, ${\acute{A}}lvarez$-Ruiz et al. [1] initiated the study of a new parameter related to Roman dominating function, which is called strong Roman domination. ${\acute{A}}lvarez$-Ruiz et al. posed the following problem: Characterize the graphs G with equal strong Roman domination number and Roman domination number. In this paper, we construct a family of trees. We prove that for a tree, its strong Roman dominance number and Roman dominance number are equal if and only if the tree belongs to this family of trees.

The Effect of Transformation on the Virulence of Streptococcus pneumoniae

Xue-Mei Zhang,Yi-Bing Yin,Dan Zhu,Bao-De Chen,Jin-Yong Luo,Yi-Ping Deng,Ming-Fang Liu,Shu-Hui Chen,Jiang-Ping Meng,Kai Lan,Yuan-Shuai Huang,Ge-Fei Kang 한국미생물학회 2005 The journal of microbiology Vol.43 No.4

Although pneumococcus is one of the most frequently encountered opportunistic pathogen in the world, the mechanisms responsible for its infectiveness have not yet been fully understood. In this paper, we have attempted to characterize the effects of pneumococcal transformation on the pathogenesis of the organism. We constructed three transformation-deficient pneumococcal strains, which were designated as Nos. 1d, 2d, and 22d. The construction of these altered strains was achieved via the insertion of the inactivated gene, comE, to strains 1, 2 and 22. We then conducted a comparison between the virulence of the transformation-deficient strains and that of the wild-type strains, via an evaluation of the ability of each strain to adhere to endothelial cells, and also assessed psaA mRNA expression, and the survival of hosts after bacterial challenge. Compared to what was observed with the wild-type strains, our results indicated that the ability of all of the transformation-deficient strains to adhere to the ECV304 cells had been significantly reduced (p < 0.05), the expression of psaA mRNA was reduced significantly (p < 0.05) in strains 2d and 22d, and the median survival time of mice infected with strains 1d and 2d was increased significantly after intraperitoneal bacterial challenge (p < 0.05). The results of our study also clearly indicated that transformation exerts significant effects on the virulence characteristics of S. pneumoniae, although the degree to which this effect is noted appears to depend primarily on the genetic background of the bacteria.

Strong Roman Domination in Grid Graphs

Chen, Xue-Gang,Sohn, Moo Young Department of Mathematics 2019 Kyungpook mathematical journal Vol.59 No.3

Consider a graph G of order n and maximum degree ${\Delta}$. Let $f:V(G){\rightarrow}\{0,1,{\cdots},{\lceil}{\frac{{\Delta}}{2}}{\rceil}+1\}$ be a function that labels the vertices of G. Let $B_0=\{v{\in}V(G):f(v)=0\}$. The function f is a strong Roman dominating function for G if every $v{\in}B_0$ has a neighbor w such that $f(w){\geq}1+{\lceil}{\frac{1}{2}}{\mid}N(w){\cap}B_0{\mid}{\rceil}$. In this paper, we study the bounds on strong Roman domination numbers of the Cartesian product $P_m{\square}P_k$ of paths $P_m$ and paths $P_k$. We compute the exact values for the strong Roman domination number of the Cartesian product $P_2{\square}P_k$ and $P_3{\square}P_k$. We also show that the strong Roman domination number of the Cartesian product $P_4{\square}P_k$ is between ${\lceil}{\frac{1}{3}}(8k-{\lfloor}{\frac{k}{8}}{\rfloor}+1){\rceil}$ and ${\lceil}{\frac{8k}{3}}{\rceil}$ for $k{\geq}8$, and that both bounds are sharp bounds.

Current understanding of the development of sex attractant-based biocontrol in burnet moths

Chen Xue-Min,Wang Xiao-Yun,Lu Wen,Zheng Xia-Lin 한국응용곤충학회 2021 Journal of Asia-Pacific Entomology Vol.24 No.3

Burnet moths, also known as the family Zygaenidae, are a typical diurnal family of Lepidoptera. Some species are important insect pests in agriculture and forestry. The use of sex attractants is one of the most important mea sures in the integrated pest management of burnet moths because these attractants are highly efficient, do not cause pollution, and are convenient and harmless to natural enemies. The earliest information about sex pher omones in Zygaenidae was reported in 1972. To date, many studies have described sex pheromones and at tractants of species in Zygaenidae. Here, we review a total of 22 sex attractant compositions identified for 57 species of Zygaenidae and compare the differences in the structures of sex attractants among these species. The application of sex attractants in seasonal monitoring showed that the main activity period of zygaenid moths is from May to September each year. However, there are few reports on the effects of sex attractants on mass trapping of members of the family Zygaenidae. The ratio and degradation of sex attractants and the trap color, shape and hanging height were considered the main factors influencing capture effectiveness. Directions for further study of burnet moths are also discussed.

ON [1, 2]-DOMINATION IN TREES

Chen, Xue-Gang,Sohn, Moo Young Korean Mathematical Society 2018 대한수학회논문집 Vol.33 No.2

Chellai et al. [3] gave an upper bound on the [1, 2]-domination number of tree and posed an open question "how to classify trees satisfying the sharp bound?". Yang and Wu [5] gave a partial solution for tree of order n with ${\ell}$-leaves such that every non-leaf vertex has degree at least 4. In this paper, we give a new upper bound on the [1, 2]-domination number of tree which extends the result of Yang and Wu. In addition, we design a polynomial time algorithm for solving the open question. By using this algorithm, we give a characterization on the [1, 2]-domination number for trees of order n with ${\ell}$ leaves satisfying $n-{\ell}$. Thereby, the open question posed by Chellai et al. is solved.

Digital Transformation, Manipulation of Asset Evaluation and M&A Performance: Discussion on the Intermediary Effect of Internal Control

Chen Chen,Hee-Jung Lee,Nan Hui,Xue-Hua Qian 강원대학교 경영경제연구소 2023 Asia-Pacific Journal of Business Vol.14 No.1

Purpose - The purpose of this study was to examine the internal relevance between digital transformation, manipulation of asset evaluation and corporate M&A performance and further explores the impact path of manipulation of asset valuation on corporate M&A performance. Design/methodology/approach - This study based on the financial data of A-share listed companies in Shanghai and Shenzhen Stock Exchanges from 2013 to 2021. Findings - First, manipulation of asset evaluation is negatively correlated with M&A performance. Second, Digital transformation significantly weakens the negative correlation between manipulation of asset evaluation and corporate M&A performance. Third, The effectiveness of internal control plays a partially intermediary role in the process of manipulation of asset evaluation affecting M&A performance. Research implications or Originality - Enriching the existing literature on the subject, the study can also provide useful reference for improving the performance of corporate mergers and acquisitions, regulating asset valuation, promoting the digital transformation of enterprises and improving internal control mechanisms, with both theoretical and practical implications.

Hot Forging Process Design Optimization Based on Approximate Model and FEM Simulation

Chen, Xue Wen,Jung, Dong Won,Sun, Ai Xue Trans Tech Publications, Ltd. 2008 Materials science forum Vol.575 No.-

<P>Technology and die design are very important in the development of forging products due to its great influence on the quality, cost and manufacturing efficiency of the final products as well as the life of the forging die. In the environment of the severe competition, how to improve the quality of forging technology and die design, to reduce the product cost and ultimately to enhance competitiveness of the forging factory are the problems that forging technology and die designer have to solve. In order to improve the quality of forging technology and die design, a design optimization method based on approximate model (response surface model) and FEM technique for hot forging process is proposed in this paper. During design optimization process, finite element analysis is incorporated to calculate the objective function and check the design alternatives. Design of experiment (DOE) method is used to collect sample points and calculate the polynomial coefficients of response surface model, and approximate model is used to calculate the optimum search direction. Finally, a case study is conducted for a gear workpiece hot forging process. The objective function is the degree of uniformity of equivalent-strain, which can be defined as mean square deviation of the equivalent-strain in each element and the average equivalent-strain of all elements, and the design parameters are the initial H0/D0 ratio of billet and the key dimensions of the die. Then the design optimization mathematical model is established. The result shows that the objective function value is dropped from 0.7914 and converges at 0.4843 within 17 iterations, the optimal design parameters are obtained.</P>

Aramid Nanofibers Reinforced Polyacrylonitrile Nanocomposite Films with High Transparency and High Mechanical Properties

Xue Bai,Yinghui Zhao,Zhenhu Song,Hui Chen,Sihang Zhang,Yonghui Luo,YingChun Gu,Shijian Tu,Guo Yao,Sheng Chen 한국섬유공학회 2022 Fibers and polymers Vol.23 No.3

The preparation of polymer nanocomposites combined with high strength, toughness, and high transparencyremains a challenge. Aramid fibers are often used as fiber-reinforced materials for their superior mechanical and thermalproperties, but the weak interfacial force between aramid fibers and matrix polymer limits the application in compositematerials. In this work, aramid nanofibers were prepared by a two-step process, which included deprotonation and acidhydrothermal treatment to obtain better dispersions in general solvents. The hydrothermal aramid nanofibers (HANFs) wereused as reinforcing materials and blended with polyacrylonitrile (PAN) to prepare polyacrylonitrile/aramid nanofibers (PAN/HANFs) composite films with different mass fractions of HANFs. The morphologies of HANFs and the thermal, optical, andmechanical properties of composite films were investigated. Interestingly, when the mass fraction of aramid nanofibers wasless than 1.0 %, the composite films were synchronously strengthened and toughened. When the mass fraction of HANFswas 0.5 %, the tensile strength and toughness of the PAN/HANFs composite film reached 62.04 MPa and 22.56 MJ/m3,which were 74.23 % and 162.31 % higher than the pure PAN film, respectively. Besides, its average transmittance in thevisible light region remained 76.34 %. This work may offer a novel and facile strategy for high transparent reinforcedpolymer composites, which have potential applications in high strength fiber or optical film.

Characterization of Surface Layer Proteins in Lactobacillus crispatus Isolate ZJ001

Xue Yan Chen,Yang Chen,Xiao Liang Li,Ning Chen,Wei Huan Fang 한국미생물 · 생명공학회 2009 Journal of microbiology and biotechnology Vol.19 No.10

The Loss Calculation of RCD Snubber with Forward and Reverse Recovery Effects Considerations

Chen Cai,Pei Xue-jun,Chen Yu,Kang Yong 전력전자학회 2011 ICPE(ISPE)논문집 Vol.2011 No.5

This paper addresses the problem of turn-off and turn-on performances of a RCD snubber circuit in high power inverter that works with insulated gate bipolar transistor (IGBT). The RCD snubber circuit turn-off and turn-on dynamics, forward and reverse recovery effects of the associated freewheeling and snubber diodes, and corresponding snubber losses are analyzed. Voltage impacts occur across the snubber resistor due to the snubber diode’s forward and reverse recovery effects, which bring in additional snubber losses. The turn-on current rising rates have two parts due to the anti-parallel free-wheeling diode (FWD) reverse recovery current that will influence the RCD loss. Moreover, the snubber has the same clamping effect as turn-off due to the anti-parallel FWD’s reverse recovery current. In addition, the proposed analysis was experimentally verified, the snubber loss are presented and discussed in the paper. Moreover, a well-designed temperature measurement is proposed to evaluate the loss.