Packing trees into complete k-partite graph

Yanling Peng,Hong Wang 대한수학회 2022 대한수학회보 Vol.59 No.2

In this work, we confirm a weak version of a conjecture proposed by Hong Wang. The ideal of the work comes from the tree packing conjecture made by Gy\'arf\'as and Lehel. Bollob\'as confirms the tree packing conjecture for many small tree, who showed that one can pack $T_1,T_2,\ldots,T_{n/\sqrt{2}}$ into $K_n$ and that a better bound would follow from a famous conjecture of Erd\H{o}s. In a similar direction, Hobbs, Bourgeois and Kasiraj made the following conjecture: Any sequence of trees $T_1,T_2,\ldots,T_n$, with $T_i$ having order $i$, can be packed into $K_{n-1,\lceil n/2\rceil}$. Further Hobbs, Bourgeois and Kasiraj \cite{3} proved that any two trees can be packed into a complete bipartite graph $K_{n-1,\lceil n/2\rceil}$. Motivated by the result, Hong Wang propose the conjecture: For each $k$-partite tree $T(\mathbb{X})$ of order $n$, there is a restrained packing of two copies of $T(\mathbb{X})$ into a complete $k$-partite graph $B_{n+m}(\mathbb{Y})$, where $m=\lfloor\frac{k}{2}\rfloor$. Hong Wong \cite{4} confirmed this conjecture for $k=2$. In this paper, we prove a weak version of this conjecture.

Short-Term Wind Speed Forecast Based on Least Squares Support Vector Machine

Wang, Yanling,Zhou, Xing,Liang, Likai,Zhang, Mingjun,Zhang, Qiang,Niu, Zhiqiang Korea Information Processing Society 2018 Journal of information processing systems Vol.14 No.6

There are many factors that affect the wind speed. In addition, the randomness of wind speed also leads to low prediction accuracy for wind speed. According to this situation, this paper constructs the short-time forecasting model based on the least squares support vector machines (LSSVM) to forecast the wind speed. The basis of the model used in this paper is support vector regression (SVR), which is used to calculate the regression relationships between the historical data and forecasting data of wind speed. In order to improve the forecast precision, historical data is clustered by cluster analysis so that the historical data whose changing trend is similar with the forecasting data can be filtered out. The filtered historical data is used as the training samples for SVR and the parameters would be optimized by particle swarm optimization (PSO). The forecasting model is tested by actual data and the forecast precision is more accurate than the industry standards. The results prove the feasibility and reliability of the model.

Discrete theory of rolling elements for a cageless ball bearing

Yanling Zhao,Qiyu Wang,Mingzhu Wang,Chengyi Pan,Yudong Bao 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.4

For the case of magnetic levitation loss, the rotor of an active magnetic bearing is forced by gravity to drop onto stator laminations, and cageless touchdown bearings with high rigidity and load-bearing capacity ensure back-up support. However, the contact collision of rolling elements in a cageless bearing will lead to deterioration of bearing performance and instability of the rotor system. For this purpose, a method based on noncontact between adjacent rolling elements in cageless bearings is proposed in this paper. First, combined with space geometry, the contact process and the change in radius of rotation when a rolling element passes through a discrete groove are analysed, and a clearance between the adjacent rolling elements is generated by changing the rotation speed. Based on this, a design principle for setting a discrete groove on an outer ring raceway is proposed, and the equation for the circumferential discrete clearance for the rolling element based on bearing kinematics is given. Combined with the characteristics of discrete groove structures, a differential equation for the discrete dynamics of rolling elements with variable stiffness coefficients is proposed. We then determine the influence of the discrete groove structure on the discrete motion of the rolling element and bearing dynamic characteristics. Third, the dynamics simulation is combined with a vibration characteristics experiment and discrete motion experiment for a rolling element in a cageless bearing. Our research results show that a discrete groove design for the raceway can be used to realize stable discrete motion of the rolling element, and that such a discrete groove structure will not adversely affect the vibration characteristics of the bearing. The feasibility of the discrete design of cageless bearings with rolling element is verified, and theoretical guidance for the development and application of cageless bearings is provided.

A LYAPUNOV CHARACTERIZATION OF ASYMPTOTIC CONTROLLABILITY FOR NONLINEAR SWITCHED SYSTEMS

Wang, Yanling,Qi, Ailing Korean Mathematical Society 2014 대한수학회보 Vol.51 No.1

In this paper, we show that general nonlinear switched systems are asymptotically controllable if and only if there exist control-Lyapunov functions for their relaxation systems. If the switching signal is dependent on the time, then the control-Lyapunov functions are continuous. And if the switching signal is dependent on the state, then the control-Lyapunov functions are $C^1$-smooth. We obtain the results from the viewpoint of control system theory. Our approach is based on the relaxation theorems of differential inclusions and the classic Lyapunov characterization.

Short-Term Wind Speed Forecast Based on Least Squares Support Vector Machine

Yanling Wang,Xing Zhou,Likai Liang,Mingjun Zhang,Qiang Zhang,Zhiqiang Niu 한국정보처리학회 2018 Journal of information processing systems Vol.14 No.6

There are many factors that affect the wind speed. In addition, the randomness of wind speed also leads to lowprediction accuracy for wind speed. According to this situation, this paper constructs the short-timeforecasting model based on the least squares support vector machines (LSSVM) to forecast the wind speed. The basis of the model used in this paper is support vector regression (SVR), which is used to calculate theregression relationships between the historical data and forecasting data of wind speed. In order to improvethe forecast precision, historical data is clustered by cluster analysis so that the historical data whose changingtrend is similar with the forecasting data can be filtered out. The filtered historical data is used as the trainingsamples for SVR and the parameters would be optimized by particle swarm optimization (PSO). Theforecasting model is tested by actual data and the forecast precision is more accurate than the industrystandards. The results prove the feasibility and reliability of the model.

Research on The Advanced Block Neighborhood Relevance Algorithm in Face Recognition

Yanling Wang,Guanglun Li 보안공학연구지원센터 2016 International Journal of Signal Processing, Image Vol.9 No.7

Characterization of Brain Microstructural Abnormalities in High Myopia Patients: A Preliminary Diffusion Kurtosis Imaging Study

Wang Huihui,Wen Hongwei,Li Jing,Chen Qian,Li Shanshan,Wang Yanling,Wang Zhenchang 대한영상의학회 2021 Korean Journal of Radiology Vol.22 No.7

Objective: To evaluate microstructural damage in high myopia (HM) patients using 3T diffusion kurtosis imaging (DKI). Materials and Methods: This prospective study included 30 HM patients and 33 age- and sex-matched healthy controls (HCs) with DKI. Kurtosis parameters including kurtosis fractional anisotropy (FA), mean kurtosis (MK), axial kurtosis (AK), and radial kurtosis (RK) as well as diffusion metrics including FA, mean diffusivity, axial diffusivity (AD), and radial diffusivity derived from DKI were obtained. Group differences in these metrics were compared using tract-based spatial statistics. Partial correlation analysis was used to evaluate correlations between microstructural changes and disease duration. Results: Compared to HCs, HM patients showed significantly reduced AK, RK, MK, and FA and significantly increased AD, predominately in the bilateral corticospinal tract, right inferior longitudinal fasciculus, superior longitudinal fasciculus, inferior fronto-occipital fasciculus, and left thalamus (all p < 0.05, threshold-free cluster enhancement corrected). In addition, DKI-derived kurtosis parameters (AK, RK, and MK) had negative correlations (r = -0.448 to -0.376, all p < 0.05) and diffusion parameter (AD) had positive correlations (r = 0.372 to 0.409, all p < 0.05) with disease duration. Conclusion: HM patients showed microstructural alterations in the brain regions responsible for motor conduction and visionrelated functions. DKI is useful for detecting white matter abnormalities in HM patients, which might be helpful for exploring and monitoring the pathogenesis of the disease.

A Lyapunov characterization of asymptotic controllability for nonlinear switched systems

Yanling Wang,Ailing Qi 대한수학회 2014 대한수학회보 Vol.51 No.1

In this paper, we show that general nonlinear switched systems are asymptotically controllable if and only if there exist control-Lyapunov functions for their relaxation systems. If the switching signal is dependent on the time, then the control-Lyapunov functions are continuous. And if the switching signal is dependent on the state, then the control-Lyapunov functions are $C^1$-smooth. We obtain the results from the viewpoint of control system theory. Our approach is based on the relaxation theorems of differential inclusions and the classic Lyapunov characterization.

Shorter Telomere Length Is Associated with Increased Breast Cancer Risk in a Chinese Han Population: A Case-Control Analysis

Zhaoxia Wang,Zhenxing Zhang,Yanling Guo,Huifeng Shui,Guoqi Liu,Tianbo Jin,Huijie Wang 한국유방암학회 2018 Journal of breast cancer Vol.21 No.4

Purpose: The aim of this study was to investigate the association of telomere length with breast cancer risk. We simultaneously explored the association between telomerase reverse transcriptase gene polymorphisms and telomere length. Methods: We used real-time quantitative polymerase chain reaction to measure relative telomere length (RTL) in genomic DNA extracted from peripheral blood from 183 breast cancer cases and 191 healthy controls. Genotyping was performed using the Sequenom MassARRAY platform. Results: Our results show that breast cancer patients had significantly shorter RTLs than control subjects (p< 0.05). When the RTLs were categorized into tertiles, we found that the lowest RTL was significantly associated with increased breast cancer risk compared with the highest RTL (odds ratio [OR], 2.33; 95% confidence interval [CI], 1.40–3.90; p=0.001). Subgroup analyses indicated that risk of breast cancer was also significantly increased in the lowest RTL compared with the highest RTL in age >40 years (OR, 2.41; 95% CI, 1.31–4.43; p=0.005), body mass index ≤24 kg/m2 (OR, 2.81; 95% CI, 1.55–5.10; p=0.001), and postmenopausal women (OR, 3.94; 95% CI, 1.63–9.51; p=0.002), respectively. In addition, individuals with the AA genotype of rs2853677 have longer telomeres than those of breast cancer patients with the AG genotype (p= 0.011). Conclusion: Our results suggest that shorter RTL was associated with an increased risk of breast cancer. An association was found between the AA genotype of rs2853677 and longer RTLs in the case group. Functional studies are warranted to validate this association and further investigate our findings.

SDSS J013127.34-032100.1: A NEWLY DISCOVERED RADIO-LOUD QUASAR AT <i>z</i> = 5.18 WITH EXTREMELY HIGH LUMINOSITY

Yi, Wei-Min,Wang, Feige,Wu, Xue-Bing,Yang, Jinyi,Bai, Jin-Ming,Fan, Xiaohui,Brandt, William N.,Ho, Luis C.,Zuo, Wenwen,Kim, Minjin,Wang, Ran,Yang, Qian,Zhang, Ju-jia,Wang, Fang,Wang, Jian-Guo,Ai, Yanl IOP Publishing 2014 ASTROPHYSICAL JOURNAL LETTERS - Vol.795 No.2

<P>Very few of the z > 5 quasars discovered to date have been radio-loud, with radio-to-optical flux ratios (radio-loudness parameters) higher than 10. Here we report the discovery of an optically luminous radio-loud quasar, SDSS J013127.34-032100.1 (J0131-0321 in short), at z = 5.18 +/- 0.01 using the Lijiang 2.4 m and Magellan telescopes. J0131-0321 has a spectral energy distribution consistent with that of radio-loud quasars. With an i-band magnitude of 18.47 and a radio flux density of 33 mJy, its radio-loudness parameter is similar to 100. The optical and near-infrared spectra taken by Magellan enable us to estimate its bolometric luminosity to be L-bol similar to 1.1 x 10(48) erg s(-1), approximately 4.5 times greater than that of the most distant quasar known to date. The black hole mass of J0131-0321 is estimated to be 2.7 x 10(9) M-circle dot, with an uncertainty up to 0.4 dex. Detailed physical properties of this high-redshift, radio-loud, potentially super-Eddington quasar can be probed in the future with more dedicated and intensive follow-up observations using multi-wavelength facilities.</P>