Robust estimation with a modified Huber’s loss for partial functional linear models based on splines

Cai Xiong,Xue Liugen,Lu Fei 한국통계학회 2020 Journal of the Korean Statistical Society Vol.49 No.4

In this article, we consider a new robust estimation procedure for the partial functional linear model (PFLM) with the slope function approximated by spline basis functions. This robust estimation procedure applies a modifed Huber’s function with tail function replaced by the exponential squared loss (ESL) to achieve robustness against outliers. A data-driven procedure is presented for selecting the tuning parameters of the new estimation method, which enables us to reach better robustness and efciency than other methods in the presence of outliers or non-normal errors. We construct robust estimators of both parametric coefcients and function coefcient in the PFLM. Moreover, some asymptotic properties of the resulting estimators are established. The fnite sample performance of our proposed method is studied through simulations and illustrated with a data example.

A Power and Performance Management Simulation Platform for Web Application Server Cluster

Zhi Xiong,Zhongliang Xue,Weihong Cai,Lingru Cai,Juan Yang 보안공학연구지원센터 2016 International Journal of Future Generation Communi Vol.9 No.12

Web application server cluster has been widely used to improve the performance of web application servers. Because web load is highly variable, we need to dynamically manage cluster’s deployment so as to reduce power consumption and meanwhile satisfy load performance demand. To facilitate researchers to evaluate a management strategy or choose key parameters for it, we propose a CloudSim-based simulation platform in this paper. It can simulate different cluster deployment algorithm, request scheduling algorithm and load feature, where cluster’s deployment includes the on/off state, CPU frequency and request scheduling parameter(s) of each server. By the aid of HookTimer component, the platform supports periodical and conditional deployment trigger modes, and can calculate some common performance indicators. The usage of interface, dynamic proxy technique and XML configuration file make the platform have good extensibility and configurability. In addition, a request-number-triggered management strategy is proposed and simulated by the platform. The simulation results demonstrate the feasibility of the platform.

Directed Evolution of Beta-galactosidase from Escherichia coli into Beta-glucuronidase

Xiong, Ai-Sheng,Peng, Ri-He,Zhuang, Jing,Liu, Jin-Ge,Xu, Fang,Cai, Bin,Guo, Zhao-Kui,Qiao, Yu-Shan,Chen, Jian-Min,Zhang, Zhen,Yao, Quan-Hong Korean Society for Biochemistry and Molecular Biol 2007 Journal of biochemistry and molecular biology Vol.40 No.3

In vitro directed evolution through DNA shuffling is a powerful molecular tool for creation of new biological phenotypes. E. coli $\beta$-galactosidase and $\beta$-glucuronidase are widely used, and their biological function, catalytic mechanism, and molecular structures are well characterized. We applied an in vitro directed evolution strategy through DNA shuffling and obtained five mutants named YG6764, YG6768, YG6769, YG6770 and YG6771 after two rounds of DNA shuffling and screening, which exhibited more $\beta$-glucuronidase activity than wild-type $\beta$-galactosidase. These variants had mutations at fourteen nucleic acid sites, resulting in changes in ten amino acids: S193N, T266A, Q267R, V411A, D448G, G466A, L527I, M543I, Q626R and Q951R. We expressed and purified those mutant proteins. Compared to the wild-type protein, five mutant proteins exhibited high $\beta$-glucuronidase activity. The comparison of molecular models of the mutated and wildtype enzymes revealed the relationship between protein function and structural modification.

Occluded and Low Resolution Face Detection with Hierarchical Deformable Model

Xiong Yang,Gang Peng,Zhaoquan Cai,Kehan Zeng 한국정보기술융합학회 2013 JoC Vol.4 No.2

This paper presents a hierarchical deformable model for robust human face detection, especially with occlusions and under low resolution. By parsing, we mean inferring the parse tree (a configuration of the proposed hierarchical model) for each face instance. In modeling, a three-layer hierarchical model is built consisting of six nodes. For each node, an active basis model is trained, and their spatial relations such as relative locations and scales are modeled using Gaussian distributions. In computing, we run the learned active basis models on testing images to obtain bottom-up hypotheses, followed by explicitly testing the compatible relations among those hypotheses to do verification and construct the parse tree in a top-down manner. In experiments, we test our approach on CMU+MIT face test set with improved performance obtained.

Validity and Reliability of Upper Limb Functional Assessment Using the Microsoft Kinect V2 Sensor

Cai, Laisi,Ma, Ye,Xiong, Shuping,Zhang, Yanxin Hindawi 2019 Applied bionics and biomechanics Vol.2019 No.-

<P><B>Objective</B></P><P> To quantify the concurrent accuracy and the test-retest reliability of a Kinect V2-based upper limb functional assessment system. </P><P><B>Approach</B></P><P> Ten healthy males performed a series of upper limb movements, which were measured concurrently with Kinect V2 and the Vicon motion capture system (gold standard). Each participant attended two testing sessions, seven days apart. Four tasks were performed including hand to contralateral shoulder, hand to mouth, combing hair, and hand to back pocket. Upper limb kinematics were calculated using our developed kinematic model and the UWA model for Kinect V2 and Vicon. The interdevice coefficient of multiple correlation (CMC) and the root mean squared error (RMSE) were used to evaluate the validity of the kinematic waveforms. Mean absolute bias and Pearson's <I>r</I> correlation were used to evaluate the validity of the angles at the points of target achieved (PTA) and the range of motion (ROM). The intersession CMC and RMSE and the intraclass correlation coefficient (ICC) were used to assess the test-retest reliability of Kinect V2. </P><P><B>Main Results</B></P><P> Both validity and reliability are found to be task-dependent and plane-dependent. Kinect V2 had good accuracy in measuring shoulder and elbow flexion/extension angular waveforms (CMC > 0.87), moderate accuracy of measuring shoulder adduction/abduction angular waveforms (CMC = 0.69-0.82), and poor accuracy of measuring shoulder internal/external angles (CMC < 0.6). We also found high test-retest reliability of Kinect V2 in most of the upper limb angular waveforms (CMC = 0.75-0.99), angles at the PTA (ICC = 0.65-0.91), and the ROM (ICC = 0.68-0.96). </P><P><B>Significance</B></P><P> Kinect V2 has great potential as a low-cost, easy implemented device for assessing upper limb angular waveforms when performing functional tasks. The system is suitable for assessing relative within-person change in upper limb motions over time, such as disease progression or improvement due to intervention.</P>

Radiosensitization Effect of Overexpression of Adenovirus-mediated SIRT6 on A549 Non-small Cell Lung Cancer Cells

Cai, Yong,Sheng, Zhao-Ying,Liang, Shi-Xiong Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.17

Objective: To explore the radiosensitization effect of overexpression of silent information regulator 6 (SIRT6) on A549 non-small cell lung cancer (NSCLC) cells. Methods: Adenovirus vector Ad-SIRT6 causing overexpression of SIRT6 was established. Western blotting and MTT assay were adopted to detect the level of SIRT6 protein and the inhibitory rate of A549 cell proliferation after different concentrations of adenovirus transduction (0, 25, 100, 200, and 400 pfu/cell) for 24 h. Control group, Ad-null group and Ad-SIRT6 group were designed in this experiment and virus concentration of the latter two groups was 200 pfu/cell. Colony formation assays were employed to test survival fraction (SF) of the 3 groups after 0, 2, 4, 6, 8, 10 X-ray irradiation. Flow cytometry was used to detect the status of cell cycle of 3 groups after 48 h of 4Gy X-ray irradiation and Western blotting was used to determine the expression of apoptosis-related genes of 3 groups after 48 h of 4GyX-ray irradiation. Results: In the range of 25~400 pfu/cell, the inhibitory rate of A549 cell proliferation increased as adenovirus concentration raised. The inhibitory rates under the concentrations of 0, 25, 100, 200, and 400 pfu/cell were 0%, $4.23{\pm}0.34%$, $12.7{\pm}2.57%$, $22.6{\pm}3.38%$, $32.2{\pm}3.22%$, $38.7{\pm}4.09%$ and $47.8{\pm}5.58%$ and there were significantly differences among groups (P<0.05). SF in Ad-SIRT6 group was lower than Ad-null and control groups after 4~10Gy X-ray irradiation (P<0.05) and the sensitization enhancement ratio (SER) was 1.35 when compared with control group. Moreover, after 48 h of 4Gy X-ray irradiation, there appeared a significant increase in G1-phase cell proportion, upregulated expression of the level of apoptosis-promoting genes (Bax and Cleaved caspase-3), but a obvious decline in S-phase and G2-phase cell proportion and a significant decrease of the level of apoptosis-inhibiting gene (Bal-2) in the Ad-SIRT6 group (P<0.05). Conclusion: The over-expression of adenovirus-mediated SIRT6, which has radiosensitization effect on A549 cells of NSCLC, can inhibit the proliferation of A549 cells and cause G0/G1 phase retardation as well as induce apoptosis of cells.

Optimization Design of Zero-Voltage-Switching Control in S-LCC Inductive Power Transfer System Under Dynamic Coupling Coefficient

Cai Jin,Wu Xusheng,Sun Pan,Sun Jun,Xiong Qiao 대한전기학회 2021 Journal of Electrical Engineering & Technology Vol.16 No.6

To obtain high effi ciency and reduced EMI in the inductive power transfer (IPT) system, it is crucial to understand the zerovoltage-switching (ZVS) control of the inverter. The frequency tracking method is usually adopted to achieve ZVS operation. However, the eff ect of frequency bifurcation in the series-inductor-capacitor-capacitor (S-LCC) system results in frequency tracking failure. To solve this problem, this paper proposes a parameter optimization design for the S-LCC system to achieve ZVS operation under the dynamic coupling coeffi cient. The analytical solution of the bifurcation frequency of the S-LCC system and the boundary conditions of the frequency bifurcation are derived through the fundamental harmonic model. Based on this boundary condition, a parameter design strategy with no frequency bifurcation under the dynamic coupling coeffi cient is established. The maximum critical coupling coeffi cient of the system is obtained by numerical analysis. Then, a frequency tracking strategy based on a phase-locked loop is given to realize ZVS control. Within the critical coupling coeffi cient, frequency bifurcation does not occur in the S-LCC topology. Finally, a 2 kW test prototype is built up to verify the feasibility of the theory.

Neighborhood coreness algorithm for identifying a set of influential spreaders in complex networks

( Xiong Yang ),( De-cai Huang ),( Zi-ke Zhang ) 한국인터넷정보학회 2017 KSII Transactions on Internet and Information Syst Vol.11 No.6

In recent years, there has been an increasing number of studies focused on identifying a set of spreaders to maximize the influence of spreading in complex networks. Although the k-core decomposition can effectively identify the single most influential spreader, selecting a group of nodes that has the largest k-core value as the seeds cannot increase the performance of the influence maximization because the propagation sphere of this group of nodes is overlapped. To overcome this limitation, we propose a neighborhood coreness cover and discount heuristic algorithm named “NCCDH” to identify a set of influential and decentralized seeds. Using this method, a node in the high-order shell with the largest neighborhood coreness and an uncovered status will be selected as the seed in each turn. In addition, the neighbors within the same shell layer of this seed will be covered, and the neighborhood coreness of the neighbors outside the shell layer will be discounted in the subsequent round. The experimental results show that with increases in the spreading probability, the NCCDH outperforms other algorithms in terms of the affected scale and spreading speed under the Susceptible-Infected-Recovered (SIR) and Susceptible-Infected (SI) models. Furthermore, this approach has a superior running time.

Analysis of signal cable noise currents in nuclear reactors under high neutron flux irradiation

Wu Xiong,Cai Li,Zhang Xiangju,Wu Tingyu,Jiang Jieqiong 한국원자력학회 2023 Nuclear Engineering and Technology Vol.55 No.12

Cables are indispensable in nuclear power plants for transmitting data measured by various types of detectors, such as self-powered neutron detectors (SPNDs). These cables will generate disturbing signals that must be accurately distinguished and eliminated. Given that the cable current is not very significant, previous research has focused on SPND, with little attention paid to cable evaluation and validation. This paper specifically focuses on the quantitative analysis of cables and proposes a theoretical model to predict cable noise. In this model, the reaction characteristics between irradiated neutrons and cables were discussed thoroughly. Based on the Monte Carlo method, a comprehensive simulation approach of neutron sensitivity was introduced and long-term irradiation experiments in a heavy water reactor (HWR) were designed to verify this model. The theoretical results of this method agree quite well with the experimental measurements, proving that the model is reliable and exhibits excellent accuracy. The experimental data also show that the cable current accounts for approximately 0.2% of the total current at the initial moment, but as the detector gradually depletes, it will contribute more than 2%, making it a non-negligible proportion of the total signal current

Mechanical performance and design optimization of rib-stiffened super-wide bridge deck with twin box girders in concrete

Wen Xiong,Jianshu Ye,Xuemei Gai,C.S. Cai 국제구조공학회 2013 Structural Engineering and Mechanics, An Int'l Jou Vol.48 No.3

The present study fundamentally investigated the mechanical performance of the rib-stiffened super-wide bridge deck with twin box girders in concrete, which is a very popular application to efficiently widen the bridges with normal span. The shear lag effects of the specific cross-sections were firstly studied. The spatial stress distribution and local stiffness of the bridge deck with twin box girders were then investigated under several typical wheel load conditions. Meanwhile, a comparative study for the bridge deck with and without stiffening ribs was also carried out during the investigation; thereby, a design optimization for the stiffening ribs was further suggested. Finally, aiming at the preliminary design, an approximate methodology to manually calculate the bending moments of the rib-stiffened bridge deck was analytically proposed for engineers to quickly assess its performance. This rib-stiffened bridge deck with twin box girders can be widely applied for concrete (especially concrete cable-stayed) bridges with normal span, however, requiring a super-wide bridge width due to the traffic flow.