Sanshool from Zanthoxylum L. Induces Apoptosis in Human Hepatocarcinoma HepG2 Cells

Yuming You,Min Zhou,Hongjia Lu,Gasper Gerald Shirima,Yajiao Cheng,Xiong Liu 한국식품과학회 2015 Food Science and Biotechnology Vol.24 No.6

Anti-proliferation and apoptosis induction activities of sanshool isolated from Zanthoxylum bungeanum (Rutaceae) in HepG2 cells were investigated. Cell proliferation was analyzed using MTT assays. Apoptotic bodies were observed under scanning electron microscopy. Nucleus staining using dichlorofluorescin diacetate (DAPI) was performed and the mitochondrial membrane potential (ΔΨm) using rhodamine-123 was observed under laser confocal microscopy. Sanshool inhibited cell proliferation in both a dose and time-dependent manner. The anti-proliferation activity was stimulated with apoptosis induction based on an increase in the sub-G1 cell population, DNA fragmentation, and typical apoptotic morphological changes. Sanshool also disrupted ΔΨm and up-regulated mRNA and protein expressions of p53 and caspase-3. Sanshool induced apoptosis via a mitochondrion-dependent pathway. Thus, sanshool is a potential anticancer medicine.

Observer Design for A Class of Uncertain State-Delayed Nonlinear Systems

Junwei Lu,Chunmei Feng,Shengyuan Xu,Yuming Chu 대한전기학회 2006 International Journal of Control, Automation, and Vol.4 No.4

This paper deals with the observer design problem for a class of state-delayed nonlinear systems with or without time-varying norm-bounded parameter uncertainty. The nonlinearities under consideration are assumed to satisfy the global Lipschitz conditions and appear in both the state and measured output equations. The problem we address is the design of a nonlinear observer such that the resulting error system is globally asymptotically stable. For the case when there is no parameter uncertainty, a sufficient condition for the solvability of this problem is derived in terms of linear matrix inequalities and the explicit formula of a desired observer is given. Based on this, the robust observer design problem for the case when parameter uncertainties appear is considered and the solvability condition is also given. Both of the solvability conditions obtained in this paper are delay-dependent. A numerical example is provided to demonstrate the applicability of the proposed approach.

An Improved Model Predictive Torque Control Strategy of a Shearer Semi-direct Permanent Magnet Synchronous Motor Based on Duty Cycle

Du Wenlong,Li Wei,Lu En,Sheng Lianchao,Chen Yuming,Jiang Song 대한전기학회 2021 Journal of Electrical Engineering & Technology Vol.16 No.5

In order to improve the stability of low-speed and high-torque permanent magnet synchronous motor control in the shearer semi-direct cutting system under large load fl uctuation and strong impact conditions, an improved model predictive torque control strategy based on duty cycle is proposed which can eff ectively reduce the fl ux and torque ripples and improve steadystate control performance. This method combines the separate process of the voltage vector selection and the duty cycle calculation through the predictive model combined with duty cycle. Then, the optimal voltage vector and its duration is selected simultaneously based on minimizing the cost function. In addition, in order to mitigates the computational burden of the proposed method, the voltage vectors in the fi nite control set is pre-selected using hysteresis comparator according to the motor operating status. Furthermore, the duty cycle pulse width modulation is introduced to obtain a fi xed switching frequency of the inverter. The results of simulation experiments confi rm that the proposed strategy can signifi cantly reduce the fl ux and torque ripples and improve the steady state performance while maintaining fast dynamic response.

A Compact Macromodeling Method for Characterizing Large-signal DC and AC Performance of InP and GaAs HBTs

Lin Cheng,Hongliang Lu,Yuming Zhang,Yimen Zhang 대한전자공학회 2022 Journal of semiconductor technology and science Vol.22 No.2

In this paper, a compact macromodeling method for characterizing the large-signal characteristics of heterojunction bipolar transistors (HBTs) is proposed and successfully applied to describe the DC and AC performance of InP and GaAs HBT devices. Using the Symbolically-defined Device (SDD) technology, an empirical macro circuit preserving the Spice Gummel-Poon (SGP) intrinsic network and a simplified thermal network is established. The empirical current and charge functions are embedded in the SDD macro circuit network module. Compared with other large-signal models, the proposed model description and the relevant parameter extraction are relatively simpler, and at the same time, this method can maintain high fitting accuracy. To assess the validity and the accuracy of the proposed model, the compact large-signal model is constructed for 1 µm InP HBT and 1 µm GaAs HBT. Based on the complete extraction of the model parameters, excellent consistency is obtained between the measured and modeled results.

Experimental and numerical study on pre-peak cyclic shear mechanism of artificial rock joints

Xinrong Liu,Yongquan Liu,Yuming Lu,Miaomiao Kou 국제구조공학회 2020 Structural Engineering and Mechanics, An Int'l Jou Vol.74 No.3

The pre-peak cyclic shear mechanism of two-order asperity degradation of rock joints in the direct shear tests with static constant normal loads (CNL) are investigated using experimental and numerical methods. The laboratory testing rock specimens contains the idealized and regular two-order triangular-shaped asperities, which represent the specific geometrical conditions of natural and irregular waviness and unevenness of rock joint surfaces, in the pre-peak cyclic shear tests. Three different shear failure patterns of two-order triangular-shaped rock joints can be found in the experiments at constant horizontal shear velocity and various static constant normal loads in the direct and pre-peak cyclic shear tests. The discrete element method is adopted to simulate the pre-peak shear failure behaviors of rock joints with two-order triangular-shaped asperities. The rock joint interfaces are simulated using a modified smooth joint model, where microscopic scale slip surfaces are applied at contacts between discrete particles in the upper and lower rock blocks. Comparing the discrete numerical results with the experimental results, the microscopic bond particle model parameters are calibrated. Effects of cyclic shear loading amplitude, static constant normal loads and initial waviness asperity angles on the pre-peak cyclic shear failure behaviors of triangular-shaped rock joints are also numerically investigated.

Mixed H2/H∞ Control for a Class of Nonlinear Networked Control Systems

Yanqian Wang,Junwei Lu,Ze Li,Yuming Chu 제어·로봇·시스템학회 2016 International Journal of Control, Automation, and Vol.14 No.3

In this paper, the mixed H2=H∞ control problem is investigated for a class of nonlinear discrete-time networkedcontrol systems with random network-induced delays, stochastic packet dropouts and probabilistic sensorfaults. The packet dropouts process is modeled as a homogeneous Markov chains taking values in a finite statespace. Network-induced delays occur in a random way with known upper bound. A set of stochastic variablesare exploited to describe sensor faults with different probabilistic density functions. By using a delay-dependentLyapunov functional, a mode-dependent mixed H2=H∞ controller is designed to guarantee both stochastic stabilityof the closed-loop system and the prescribed H2, H∞ control performances. Sufficient conditions for the existenceof the mixed H2=H∞ controller are presented in terms of a series of LMIs. If these LMIs are feasible, then the modedependentmixed H2=H∞ controller can be obtained. A numerical example is given to demonstrate the effectivenessof the developed method.

Low-voltage driving phototransistor based on dye-sensitized nanocrystalline titanium dioxide thin films

Xiaoqi Wang,Jia Xu,Zhiyong Liu,Yuming Lu,Chuanbing Cai 한국물리학회 2012 Current Applied Physics Vol.12 No.1

Photo-gated transistors based on dye-sensitized nanocrystalline titanium dioxide thin film are established. A transistor-like transport behavior characterized by the linear increase, saturated plateau, and breakdown-like increase in the voltageecurrent curve is achievable with a low driven bias for the present device. The response current exhibits a linear dependence on the intensity of gated light, and the measured maximum photosensitivity is approximately 0.1 A/W. The dynamic responses for various light frequencies and their dependences on the load resistances are investigated as well. The cut-off frequency of w50 Hz is abstracted, indicating the potential application for economical and efficient light switch or optical communication unit. The DC photo-gated response is explained by the energy level diagram, and is numerically simulated by an equivalent circuit model, suggesting a clear correlation between photovoltaic and photoconductive behaviors as well as their optical responses. Photo-gated transistors based on dye-sensitized nanocrystalline titanium dioxide thin film are established. A transistor-like transport behavior characterized by the linear increase, saturated plateau, and breakdown-like increase in the voltageecurrent curve is achievable with a low driven bias for the present device. The response current exhibits a linear dependence on the intensity of gated light, and the measured maximum photosensitivity is approximately 0.1 A/W. The dynamic responses for various light frequencies and their dependences on the load resistances are investigated as well. The cut-off frequency of w50 Hz is abstracted, indicating the potential application for economical and efficient light switch or optical communication unit. The DC photo-gated response is explained by the energy level diagram, and is numerically simulated by an equivalent circuit model, suggesting a clear correlation between photovoltaic and photoconductive behaviors as well as their optical responses.

Adaptive Prescribed Performance Output Regulation of Nonlinear Systems with Nonlinear Exosystems

Fujin Jia,Cui Lei,Junwei Lu,Yuming Chu 제어·로봇·시스템학회 2020 International Journal of Control, Automation, and Vol.18 No.8

The paper studies the prescribed performance output regulation problem for a class of nonlinear uncertain strict-feedback systems which are driven by nonlinear exosystems. Fuzzy logic systems (FLSs) are used to approximate the unknown functions. A fuzzy adaptive observer is designed to estimate the system state. A fuzzy internal model is designed to reject disturbance. Simultaneously, a parameter-type Lyapunov function and L function are designed to ensure the prescribed performance of the system. As illustrated by example, the proposed prescribed performance fuzzy adaptive output feedback control scheme is shown to guarantee semi-globally uniformly ultimately bounded, and the dynamic performance and steady-state performance of the tracking error are dependent on the prescribed performance functions.

CFD simulation and optimization on airflow uniformity of material drying room used in steam blanching and hot-air vacuum drying equipment

Dong Wang,Libin Tan,Yuejin Yuan,Yuming Lu 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.10

Airflow velocity uniformity in material drying room used in steam blanching and hot-air vacuum drying equipment is crucial for obtaining a good drying quality of fruits and vegetables. To analyze the airflow velocity uniformity and give the optimization design for improving the airflow uniformity, CFD method is used for the flow field analysis of material drying room and the velocity non-uniformity coefficient is used as the evaluation indicator for the velocity uniformity. Results show that the airflow velocity distribution in the material drying room at the original inlet airflow distribution chamber is relatively uneven and the airflow velocity nonuniformity coefficient in drying area is 34 %. For reducing the airflow velocity non-uniformity, the airflow velocity distribution of three structural modification directions with 12 designs in total are analyzed and compared. The minimum airflow velocity non-uniformity coefficient for adding a spoiler model, reducing the closed end width and adding nozzle baffles are 17.1 %, 30.2 %, 10.4 %, respectively. Through comparison, adding the nozzle baffle with a width of 11 mm at the rear end of each nozzle outlet is considered as the optimal designs to conduct the experimental validation. Experimental validation results shows the the relative error between the simulated value and the measured value is within 10 %, proving that the CFD prediction results is reliable and the research results can give a theoretical reference for the designers to evaluate and optimize the structure of inlet airflow distribution chamber for improving the airflow uniformity in drying area.