2-Arc-transitive metacyclic covers of complete graphs

Xu, Wenqin,Du, Shaofei,Kwak, Jin Ho,Xu, Mingyao Elsevier 2015 Journal of combinatorial theory. Series B Vol.111 No.-

<P><B>Abstract</B></P> <P>Regular covers of complete graphs whose fibre-preserving automorphism groups act 2-arc-transitively are investigated. Such covers have been classified when the covering transformation groups <I>K</I> are cyclic groups <SUB> Z d </SUB> for an integer d ≥ 2 , metacyclic abelian groups Z p 2 , or nonmetacyclic abelian groups Z p 3 for a prime <I>p</I> (see S.F. Du et al. (1998) [5] for the first two metacyclic group cases and see S.F. Du et al. (2005) [3] for the third nonmetacyclic group case). In this paper, a complete classification is achieved of all such covers when <I>K</I> is any metacyclic group.</P>

p-Doping of organic hole transport layers in p-i-n perovskite solar cells: correlating open-circuit voltage and photoluminescence quenching

Du, Tian,Xu, Weidong,Daboczi, Matyas,Kim, Jinhyun,Xu, Shengda,Lin, Chieh-Ting,Kang, Hongkyu,Lee, Kwanghee,Heeney, Martin J.,Kim, Ji-Seon,Durrant, James R.,McLachlan, Martyn A. The Royal Society of Chemistry 2019 Journal of Materials Chemistry A Vol.7 No.32

<P>Doping is a widely implemented strategy for enhancing the inherent electronic properties of charge transport layers in photovoltaic (PV) devices. Here, in direct contrast to existing understanding, we find that a reduction in p-doping of the organic hole transport layer (HTL) leads to substantial improvements in PV performance in planar p-i-n perovskite solar cells (PSCs), driven by improvements in open circuit voltage (<I>V</I>OC). Employing a range of transient and steady state characterisation tools, we find that the improvements of <I>V</I>OC correlate with reduced surface recombination losses in less p-doped HTLs. A simple device model including screening of bulk electric fields in the perovskite layer is used to explain this observation. In particular, photoluminescence (PL) emission of complete solar cells shows that efficient performance is correlated to a high PL intensity at open circuit and a low PL intensity at short circuit. We conclude that desirable transport layers for p-i-n PSCs should be charge selective contacts with low doping densities.</P>

Experimental and numerical study on mechanical behavior of RC shear walls with precast steel-concrete composite module in nuclear power plant

Xu Haitao,Xu Jinbin,Dong Zhanfa,Ding Zhixin,Bai Mingxin,Du Xiaodong,Wang Dayang 한국원자력학회 2024 Nuclear Engineering and Technology Vol.56 No.6

Reinforced concrete (RC) shear walls with precast steel-concrete composite modular (PSCCM) are strongly recommended in the structural design of nuclear power plants due to the need for a large number of process pipeline crossings and industrial construction. However, the effect of the PSCCM on the mechanical behavior of the whole RC shear wall is still unknown and has received little attention. In this study, three 1:3 scaled specimens, one traditional shear wall specimen (TW) and two shear wall specimens with the PSCCM (PW1, PW2), were designed and investigated under cyclic loadings. The failure mode, hysteretic curve, energy dissipation, stiffness and strength degradations were then comparatively investigated to reveal the effect of the PSCCM. Furthermore, numerical models of the RC shear wall with different PSCCM distributions were analyzed. The results show that the shear wall with the PSCCM has comparable mechanical properties with the traditional shear wall, which can be further improved by adding reinforced concrete constraints on both sides of the shear wall. The accumulated energy dissipation of the PW2 is higher than that of the TW and PW1 by 98.7 % and 60.0 %. The failure of the shear wall with the PSCCM is mainly concentrated in the reinforced concrete wall below the PSCCM, while the PSCCM maintains an elastic working state as a whole. Shear walls with the PSCCM arranged in the high stress zone will have a higher load-bearing capacity and lateral stiffness, but will suffer a higher risk of failure. The PSCCM in the low stress zone is always in an elastic working state.

Cervical Cancer Mortality Trends in China, 1991-2013, and Predictions for the Future

Du, Pei-Ling,Wu, Ku-Sheng,Fang, Jia-Ying,Zeng, Yang,Xu, Zhen-Xi,Tang, Wen-Rui,Xu, Xiao-Ling,Lin, Kun Asian Pacific Journal of Cancer Prevention 2015 Asian Pacific journal of cancer prevention Vol.16 No.15

Background: To analyze cervical cancer mortality trends in China from 1991-2013 and forecast the mortality distribution in future five years (2014-2018), and provide clues for prevention and treatment. Materials and Methods: Mortality data for cervical cancer in China from 1991 to 2013 were used to describe the epidemiological characteristics and distribution, including the trend of the standardized mortality rate, urban-rural differences, and age variation. Trend-surface analysis was used to analyze the geographical distribution of mortality. Curve estimation, time series, gray modeling, and joinpoint regression were performed to predict and forecast mortality trends. Results: In recent years, the mortality rate of cervical cancer has increased, and there is also a steady increase in the incidence from 2003 to 2013 in China. Mortality rates in rural areas are higher than in urban areas. The mortality dramatically increases in the 40+ yr age group, reaching a peak in the >85 yr age group. In addition, geographical analysis showed that the cervical cancer mortality increased from the southwest to west-central and from the southeast to northeast of the country. Conclusions: The incidence rate and the mortality rate are increasing from 1991 to 2013, and the predictions show this will continue in the future. Thus, implementation of prevention and management programs for cervical cancer are necessary in China, especially for rural areas, young women in urban areas, and high risk regions (the west-central).

A complete S-shape feed rate scheduling approach for NURBS interpolator

Du, Xu,Huang, Jie,Zhu, Li-Min Society for Computational Design and Engineering 2015 Journal of computational design and engineering Vol.2 No.4

This paper presents a complete S-shape feed rate scheduling approach (CSFA) with confined jerk, acceleration and command feed rate for parametric tool path. For a Non-Uniform Rational B-Spline (NURBS) tool path, the critical points of the tool path where the radius of curvature reaches extreme values are found firstly. Then, the NURBS curve is split into several NURBS sub-curves or blocks by the critical points. A bidirectional scanning strategy with the limitations of chord error, normal/tangential acceleration/jerk and command feed rate is employed to make the feed rate at the junctions between different NURBS blocks continuous. To improve the efficiency of the feed rate scheduling, the NURBS block is classified into three types: short block, medium block and long block. The feed rate profile corresponding to each NURBS block is generated according to the start/end feed rates and the arc length of the block and the limitations of tangential acceleration/jerk. In addition, two compensation strategies are proposed to make the feed rate more continuous and the arc increment more precise. Once the feed rate profile is determined, a second-order Taylor's expansion interpolation method is applied to generate the position commands. Finally, experiments with two free-form NURBS curves are conducted to verify the applicability and accuracy of the proposed method.

Rate-User-Perceived-Quality Aware Replication Strategy for Video Streaming over Wireless Mesh Networks

( Xu Du ),( Nguyen-son Vo ),( Wenqing Cheng ),( Trung Q. Duong ) 한국인터넷정보학회 2011 KSII Transactions on Internet and Information Syst Vol.5 No.11

In this research, we consider the replication strategy for the applications of video streaming in wireless mesh networks (WMNs). In particular, we propose a closed-form of optimal replication densities for a set of frames of a video streaming by exploiting not only the skewed access probability of each frame but also the skewed loss probability and skewed encoding rate-distortion information. The simulation results demonstrate that our method improves the replication performance in terms of user-perceived quality (UPQ) which includes: 1) minimum average maximum reconstructed distortion for high peak signal-to-noise ratio (PSNR), 2) small reconstructed distortion fluctuation among frames for smooth playback, and 3) reasonable average maximum transmission distance for continuous playback. Furthermore, the proposed strategy consumes smaller storage capacity compared to other existing optimal replication strategies. More importantly, the effect of encoding rate is carefully investigated to show that high encoding rate does not always gain high performance of replication for video streaming.

Mortality Characteristic and Prediction of Nasopharyngeal Carcinoma in China from 1991 to 2013

Xu, Zhen-Xi,Lin, Zhi-Xiong,Fang, Jia-Ying,Wu, Ku-Sheng,Du, Pei-Ling,Zeng, Yang,Tang, Wen-Rui,Xu, Xiao-Ling,Lin, Kun Asian Pacific Journal of Cancer Prevention 2015 Asian Pacific journal of cancer prevention Vol.16 No.15

Background: To analyze the mortality distribution of nasopharyngeal carcinoma in China from 1991 to 2013, to predict the mortality in the ensuing five years, and to provide evidence for prevention and treatment of nasopharyngeal carcinoma. Materials and Methods: Mortality data for Nasopharyngeal Carcinoma in China from 1991 to 2013 were used to describe its epidemiological characteristics, such as the change of the standardized mortality rate, sex and age differences, urban-rural differences. Trend-surface analysis was used to study the geographical distribution of the mortality. Curve estimation, time series, gray modeling, and joinpoint regression were used to predict the mortality for the ensuing five years in the future. Results: In China, the standardized mortality rate of Nasopharyngeal Carcinoma increased with time from 1996, reaching the peak values of $1.45/10^5$ at the year of 2002, and decreased gradually afterwards. With males being 1.51 times higher than females, and the city had a higher rate than the rural during the past two decades. The mortality rate increased from age 40. Geographical analysis showed the mortality rate increased from middle to southern China. Conclusions: The standardized mortality rate of Nasopharyngeal Carcinoma is falling. The regional disease control for Nasopharyngeal Carcinoma should be focused on Guangdong province of China, and the key targets for prevention and treatment are rural men, especially after the age of 40. The mortality of Nasopharyngeal Carcinoma will decrease in the next five years.

Cross Fertility between the Whild Japanese Quail in the Weishan Lake Area and Domestic Quail

W.Xu,H.Chang,H.Y.Wang,G.B.Chang,L.Du,S.X.Lu,H.Q.Yi,Q.Xu,M.Xu,Q.H.Wang 아세아·태평양축산학회 2003 Animal Bioscience Vol.16 No.10

Seismic resistant design of highway bridge with multiple-variable frequency pendulum isolator

Xu Liang,Jianian Wen,Qiang Han,Xiuli Du 국제구조공학회 2021 Smart Structures and Systems, An International Jou Vol.28 No.2

Multiple variable frequency pendulum isolator (MVFPI) has been recently developed as a superior alternative to the traditional friction pendulum bearing (FPB) especially for the seismic isolation in near-fault regions. The MVFPI is characterized by its variable frequency and self-adaptability, which are achieved by piecewise function of sliding surface and shape memory alloy (SMA). The objective of this study is to propose the design algorithm of the MVFPIs in highway bridge as an extension of the direct displacement-based design (DDBD) framework. The nonlinearities of the structural components are taken into account in the design procedure, and the corresponding damage states satisfy the two-stage design philosophy. The accuracy and robustness of the design procedure are verified by an isolated four-span highway bridge through nonlinear time history (NLTH) analyses. The analytical results indicate that the proposed design procedure can predict the profile of deck displacement and amplitude, as well as the damage states of the piers. From statistic aspect, the fragility analyses illustrate that the bridge isolated by MVFPIs exhibits better seismic performance than that of the bridge isolated by FPBs.

Domain Adaptation Image Classification Based on Multi-sparse Representation

( Xu Zhang ),( Xiaofeng Wang ),( Yue Du ),( Xiaoyan Qin ) 한국인터넷정보학회 2017 KSII Transactions on Internet and Information Syst Vol.11 No.5

Generally, research of classical image classification algorithms assume that training data and testing data are derived from the same domain with the same distribution. Unfortunately, in practical applications, this assumption is rarely met. Aiming at the problem, a domain adaption image classification approach based on multi-sparse representation is proposed in this paper. The existences of intermediate domains are hypothesized between the source and target domains. And each intermediate subspace is modeled through online dictionary learning with target data updating. On the one hand, the reconstruction error of the target data is guaranteed, on the other, the transition from the source domain to the target domain is as smooth as possible. An augmented feature representation produced by invariant sparse codes across the source, intermediate and target domain dictionaries is employed for across domain recognition. Experimental results verify the effectiveness of the proposed algorithm.