Gene expression during the intra-puparial stage of Chrysomya megacephala: Implications for postmortem interval estimation

YuWang,Zhiya Gu,Liangliang Li,Jiangfeng Wang 한국응용곤충학회 2019 Journal of Asia-Pacific Entomology Vol.22 No.3

Chrysomya megacephala (Fabricius, 1794) (Diptera: Calliphoridae) is one of the most predominant calliphorid species which arrives and colonizes a cadaver first in its native range of the Australian and Oriental regions, and the intra-puparial stage of this species accounts for about half of its immature stage. Therefore, establishing a reliable aging method of the intra-puparial stage of C. megacephala is very important to accurately estimate the minimum postmortem interval (PMI min ). In this study, actin was used as an internal reference gene to study the expression of three genes, ecdysone receptor gene ecr, white-eye gene white, and heat shock protein gene hsp70, at different time points during intra-puparial development of C. megacephala. Quantification through real-time PCR revealed that these genes can be used to age the intra-puparial period of C. megacephala as they exhibit regular changes and gene expression level was temperature-dependent. The overall gene expression profile of ecr showed a downward trend throughout the intra-puparial stage. White expression increased steadily until it peaked when intra-puparial development reached 45%, and the expression began to decrease when the intrapuparial development reached 55%. hsp70 was first down-regulated at 0–15% of intra-puparial development, and then slightly up-regulated at 15–40%, and finally down-regulated again until the end of intra-puparial development. This study provides molecular indicators of age during the intra-puparial stage of C. megacephala, and combining gene expression with the morphological methods can lead to more accurate estimation for PMI min .

Analysis and Design of DC-link Voltage Controller in Shunt Active Power Filter

Yu Wang,Yun-Xiang Xie,Xiang Liu 전력전자학회 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.3

This study investigates the inherent influence of a DC-link voltage controller on both DC-link voltage control and the compensation performance of a three-phase, four-wire shunt active power filter (APF). A nonlinear variable-parameter DC-link voltage controller is proposed to satisfy both the dynamic characteristic of DC-link voltage control and steady-state compensation performance. Unlike in the conventional fixed-parameter controller, the parameters in the proposed controller vary according to the difference between the actual and the reference DC-link voltages. The design procedures for the nonlinear voltage controller with variable parameters are determined and analyzed so that the proposed voltage controller can be designed accordingly. Representative simulation and experimental results for the three-phase, four-wire, center-spilt shunt APF verify the analysis findings, as well as the feasibility and effectiveness of the proposed DC-link voltage controller.

DC-Link Voltage Balance Control in Three-phase Four-wire Active Power Filters

Yu Wang,Yuanpeng Guan,Yunxiang Xie,Xiang Liu 전력전자학회 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.5

The three-phase four-wire shunt active power filter (APF) is an effective method to solve the harmonic problem in three-phase four-wire power systems. In addition, it has two possible topologies, a four-leg inverter and a three-leg inverter with a split-capacitor. There are some studies investigating DC-link voltage control in three-phase four-wire APFs. However, when compared to the four-leg inverter topology, maintaining the balance between the DC-link upper and lower capacitor voltages becomes a unique problem in the three-leg inverter with a split-capacitor topology, and previous studies seldom pay attention to this fact. In this paper, the influence of the balance between the two DC-link voltages on the compensation performance, and the influence of the voltage balance controller on the compensation performance, are analyzed. To achieve the balance between the two DC-link capacitor voltages, and to avoid the adverse effect the voltage balance controller has on the APF compensation performance, a new DC-link voltage balance control strategy for the three-phase four-wire split-capacitor APF is proposed. Representative simulation and experimental results are presented to verify the analysis and the proposed DC-link voltage balance control strategy.

Assisted Magnetic Resonance Imaging Diagnosis for Alzheimer’s Disease Based on Kernel Principal Component Analysis and Supervised Classification Schemes

( Yu Wang ),( Wen Zhou ),( Chongchong Yu ),( Weijun Su ) 한국정보처리학회 2021 Journal of information processing systems Vol.17 No.1

Alzheimer’s disease (AD) is an insidious and degenerative neurological disease. It is a new topic for AD patients to use magnetic resonance imaging (MRI) and computer technology and is gradually explored at present. Preprocessing and correlation analysis on MRI data are firstly made in this paper. Then kernel principal component analysis (KPCA) is used to extract features of brain gray matter images. Finally supervised classification schemes such as AdaBoost algorithm and support vector machine algorithm are used to classify the above features. Experimental results by means of AD program Alzheimer’s Disease Neuroimaging Initiative (ADNI) database which contains brain structural MRI (sMRI) of 116 AD patients, 116 patients with mild cognitive impairment, and 117 normal controls show that the proposed method can effectively assist the diagnosis and analysis of AD. Compared with principal component analysis (PCA) method, all classification results on KPCA are improved by 2%-6% among which the best result can reach 84%. It indicates that KPCA algorithm for feature extraction is more abundant and complete than PCA.

Low-Complexity Network Coding Algorithms for Energy Efficient Information Exchange

Yu Wang,Ian D. Henning 한국통신학회 2008 Journal of communications and networks Vol.10 No.4

The use of network coding in wireless networks has been proposed in the literature for energy efficient broadcast. However, the decoding complexity of existing algorithms is too high for lowcomplexity devices. In this work we formalize the all-to-all information exchange problem and shows how to optimize the transmission scheme in terms of energy efficiency. Furthermore, we prove by construction that there exists O(1)-complexity network coding algorithms for grid networks which can achieve such optimality. We also present low-complexity heuristics for randomtopology networks. Simulation results show that network coding algorithms outperforms forwarding algorithms in most cases.

Role of Grain Refinement Mechanism on Microstructure and Performance in AZ31B Alloy During Interactive Alternating Forward Extrusion (AFE) Process

Yu Wang,Feng Li,Ye Wang,Qiang Chen,Xue Wen Li,Wen Bin Fang 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.4

In this study, interactive alternate forward extrusion (AFE) experiments with varying number of extrusion passes of AZ31magnesium alloy were carried out. The evolution of microstructure, and texture and their effects on the mechanical propertieswere studied. The results show that with the increase of loading passes, the grains are significantly refined, and thedynamic recrystallisation (DRX) structure is uniformly distributed in the product, which is the main reason for the increasein microhardness, compressive strength and failure strain. Further, slip and twinning induced DRX behaviour are consideredto be the main deformation methods in the early stage of deformation. Whereas continuous DRX is considered to be the maindeformation methods for the change in grain morphology in the later stage. During the extrusion process, the deflection angleof the base pole decreases. Finally, the fibre texture is formed; the texture strength is significantly reduced because of theeffect of recrystallisation. The AZ31 magnesium alloy interactive AFE process is discussed with respect to the technologicalexperiment and the microstructure deformation, thus providing a vital scientific basis for further application.

Adaptive DC-link Voltage Control for Shunt Active Power Filter

Yu Wang,Yun-Xiang Xie 전력전자학회 2014 JOURNAL OF POWER ELECTRONICS Vol.14 No.4

This study analyzes the mathematical relationship between DC-link voltage and system parameters for shunt active power filters (APFs). Analysis and mathematical deduction are used to determine the required minimum DC-link voltage for APF. A novel adaptive DC-link voltage controller for the three-phase four-wire shunt APF is then proposed. In this controller, the DC-link voltage reference value will be maintained at the required minimum voltage level. Therefore, power consumption and switching loss will effectively decrease. The DC-link voltage can also adaptively yield different DC-link voltage levels based on different harmonic currents and grid voltage levels and thus avoid the effects of harmonic current and grid voltage fluctuation on compensation performance. Finally, representative simulation and experimental results in a three-phase four-wire center-split shunt APF are presented to verify the validity and effectiveness of the minimum DC-link voltage design and the proposed adaptive DC-link voltage controller.

Generalized derivations with annihilator conditions in prime rings

Yu Wang 대한수학회 2011 대한수학회보 Vol.48 No.5

Let R be a prime ring, H a generalized derivation of R, L a noncentral Lie ideal of R, and 0≠ a∈ R. Suppose that au^sH(u)u^t=0 for all u∈ L, where s,t≥0 are fixed integers. Then H=0 unless R satisfies S_4, the standard identity in four variables.

Adaptive Backstepping Control for Spacecraft Rendezvous on Elliptical Orbits Based on Transformed Variables Model

Yu Wang,Kun Li,Kaihong Yang,Hai-bo Ji 제어·로봇·시스템학회 2018 International Journal of Control, Automation, and Vol.16 No.1

This paper investigates the problem of relative motion control for spacecraft rendezvous on an arbitrary elliptical orbit. The simplified dynamic model describing the relative motion between the chaser spacecraft and the target spacecraft is established via using transformed variables. Due to the presence of time variant parameters in this novel model, robust control scheme and adaptive control scheme are designed to solve the rendezvous problem. Theoretical analyses and simulation results demonstrate the effectiveness of the proposed methods.

An On-line Strategy based on Rolling State Prediction for Hybrid Energy Storage System of Tram

Yu Wang,Zhongping Yang,Fei Lin,Xiaochun Fang,Xingkun An,Hongda Zhou 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5

This paper aims at a hybrid tram with the onboard battery-supercapacitor storage system. This paper proposes an on-line strategy based on rolling state prediction (ROS). A wavelet neural network (WNN) is used to predict the running state of the tram in a certain period of time in the future according to the historic data, and the dynamic programming (DP) algorithm is used to optimize the energy management strategy (EMS) during the period. The strategy aims to optimize the system efficiency and battery life. Compared with classical rule-based (RB) strategy, ROS greatly increases the system efficiency and lengthens lifespan of battery and achieves real-time optimization.