Catalytic transfer hydrogenation of furfural to furfuryl alcohol over Al-containing ferrihydrite

Wenhai Chen,Qiao Peng,Guozhi Fan,Qunpeng Cheng,Min Tu,Guangsen Song 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.119 No.-

Al-containing ferrihydrite (Fh-Al) was prepared by co-precipitation method using ferric nitrate nonahydrateand aluminum nitrate nonahydrate as precursors. The prepared Fh-Al was systematically characterizedand then employed for the catalytic transfer hydrogenation (CTH) of furfural (FUR) to furfurylalcohol (FOL). The influence of precipitant type, hydrogen donor, the molar ratio of Fe to Al, catalystamount, reaction time and reaction temperature were investigated. It was found that Fh-Al with 1:2molar ratio of Fe to Al was amorphous with acidic and basic sites, and the largest specific surface areaof 303 m2/g was obtained using NaOH and Na2CO3 as the co-precipitator. Fh-Al with 1:2 molar ratio ofFe to Al possessed excellent catalytic performance and stability. The conversion of FUR, the yield andthe selectivity of FOL reached 100 % at 150 C for 5 h using isopropanol as the hydrogen donor. Moreover, only slight decrease in the catalytic performance was observed during the recycle. After 4cycles, the conversion of FUR, the selectivity and the yield of FOL still reached 99.1 %, 99.7 % and98.8 %, respectively. A plausible reaction mechanism for the CTH of FUR to FOL was also proposed, inwhich both acidic and basic sites play roles.

New chitosan/Konjac glucomannan blending membrane for application in pervaporation dehydration of caprolactam solution

Wenhai Lin,Qin Li,Tianrong Zhu 한국공업화학회 2012 Journal of Industrial and Engineering Chemistry Vol.18 No.3

Chitosan/Konjac glucomannan blending membranes were investigated to propose an improved caprolactam pervaporation (PV) dehydration process. The composite membranes were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray diffraction and differential scanning calorimetry measurements to assess the intermolecular interactions of membranes. The effects of different temperature, CPL concentration in feed and KGM proportion in the membranes on the pervaporation performance were investigated. Data showed that KGM/CS blending membranes displayed good swelling and pervaporation performance, and the blending membrane M-1 had superior separation factor exceed 3000 at every temperature for 70 wt.% caprolactam. The results revealed that the separation performances of KGM/CS blending membranes were strongly related to their reaction degree, intrinsic structure and operating parameters.

Study of solvent casting/particulate leaching technique membranes in pervaporation for dehydration of caprolactam

Wenhai Lin,Qin Li,Tianrong Zhu 한국공업화학회 2012 Journal of Industrial and Engineering Chemistry Vol.18 No.3

New porous and rough PVA (polyvinyl alcohol) membranes were synthesized by solvent casting/particulate leaching technique to improve caprolactam (CPL) pervaporation (PV) separation dehydration process. The membranes were characterized by FTIR, SEM, XRD, and contact angle measurements. On account of their special structure, solvent casting/particulate leaching technique membranes showed different surface morphologies compared with the original PVA membrane with enhanced hydrophilicity. By evaluating PV performance and mechanism, a PV transport equation was introduced to evaluate composite membrane permeation flux, separation factor, diffusivity/sorptivity selectivity,and activation energy. The maximum flux obtained in this work was greatly improved to 3.2 kg/m2 h and reached industrial application levels for separating CPL/water mixtures (CPL 70 wt%).

Passivity and Passification for Stochastic Systems with Markovian Switching and Generally Uncertain Transition Rates

Wenhai Qi,Yonggui Kao,Xianwen Gao 제어·로봇·시스템학회 2017 International Journal of Control, Automation, and Vol.15 No.5

The paper deals with the problems of passivity and passification for stochastic systems with Markovianswitching and generally uncertain transition rates. The considered systems are more general, which cover uncertaintransition rates and partly known transition rates as two special cases. By employing the multiple Lyapunov functionand some free-weighting matrices, a state feedback controller is constructed such that the resulted closed-loopsystem is stochastically passive. Some sufficient conditions for the solution to the problem are derived in the formof linear matrix inequalities (LMIs). Finally, a numerical example is given to demonstrate the validity of the mainresults.

Positive L1-gain Filter Design for Positive Continuous-time Markovian Jump Systems with Partly Known Transition Rates

Wenhai Qi,Xianwen Gao 제어·로봇·시스템학회 2016 International Journal of Control, Automation, and Vol.14 No.6

The paper is concerned with the problem of positive L1-gain filter design for positive continuous-timeMarkovian jump systems with partly known transition rates. Our aim is to design a positive full-order filter such thatthe corresponding filtering error system is positive and stochastically stable with L1-gain performance. By applyinga linear co-positive Lyapunov function and free-connection weighting vectors, the desired positive L1-gain filter isprovided. The obtained theoretical results are demonstrated by numerical examples.

L1 Control for Positive Markovian Jump Systems with Partly Known Transition Rates

Wenhai Qi,Xianwen Gao 제어·로봇·시스템학회 2017 International Journal of Control, Automation, and Vol.15 No.1

This paper deals with the problem of L1 control for positive Markovian jump systems with partly knowntransition rates. First, by constructing an appropriate linear co-positive type Lyapunov-Krasovskii function, stochasticstability for the underlying system is discussed. Then, the L1-gain performance is analyzed. Based on the resultsobtained, an effective method is proposed for the design of state feedback controller. All the proposed conditionsare derived to ensure that the closed-loop Markovian jump system positive and stochastically stable with L1-gainperformance in linear programming. Finally, an example is given to demonstrate the validity of the main results.

Robust stabilisation for non-linear time-delay semi-Markovian jump systems via sliding mode control

Qi, Wenhai,Park, Ju H.,Cheng, Jun,Kao, Yonggui IET 2017 IET CONTROL THEORY AND APPLICATIONS Vol.11 No.10

<P>This study deals with the problem of robust stabilisation for non-linear time-delay semi-Markovian jump systems via sliding mode control (SMC). Such a switching is governed by a semi-Markovian process which is time-varying and dependent on the sojourn-time <I>h</I>. The time delay is considered as time-varying and meets the requirements of the upper and lower bounds. By introducing free-connection weighting matrix method and Lyapunov functional, sufficient conditions for the resulting sliding mode dynamics in the form of linear matrix inequalities are derived to guarantee the closed-loop system robustly stochastically stable for all admissible uncertainties and non-linear perturbations. Then, an SMC law is synthesised to drive the system trajectories onto the predefined switching surface in a finite time. Finally, an example illustrates the validity of the obtained results.</P>

_{L 1} finite-time stabilization for positive semi-Markovian switching systems

Qi, Wenhai,Park, Ju H.,Zong, Guangdeng,Cheng, Jun Elsevier science 2019 Information sciences Vol.477 No.-

<P><B>Abstract</B></P> <P>This paper investigates robust finite-time stabilization scheme for positive semi-Markovian switching systems (S-MSSs). Semi-Markovian process (SMP), external disturbances, and transient performances at a finite-time level may appear in a controlled system. A more general system model for S-MSSs that covers Markovian switching systems (MSSs) as a special case is suitable for describing some complex systems that are subject to random abrupt changes in structure and parameter. The main motivation for this is that finite-time problems can be used to describe the transient performance of practical industrial control processes. First, under the framework of stochastic semi-Markovian Lyapunov functions theory, some sufficient conditions for finite-time boundedness (FTBs) and <SUB> L 1 </SUB> FTBs criteria for positive S-MSSs are proposed for all admissible disturbances. Then, a novel <SUB> L 1 </SUB> finite-time controller design method that employs the gain matrix decomposition method is presented to reduce some conservativeness, thereby guaranteeing that the resulting closed-loop system (RLCS) could achieve positivity, FTBs, and attain a prescribed <SUB> L 1 </SUB> noise attenuation performance index in standard linear programming (LP). Finally, a practical example is introduced to show the effectiveness of the main theory</P>

A New Approach on Digital Blood Pressure Measurement Method for u-Healthcare Systems

Boyeon Kim,Wenhai Jin,Sung Hoon Woo,Yunseok Chang 보안공학연구지원센터 2015 International Journal of Bio-Science and Bio-Techn Vol.7 No.1

The traditional blood pressure measurement method so called Kortokoff method has to apply strong air pressure on patient’s artery that could give severe damage on artery, and has the problem that method cannot measure the blood pressure in a series or continuously. But recent engineering technology can give new solutions that can solve the problems by using digital sensors and microcomputer. In this paper, we proposed a kind of non-Kortokoff method that can get the blood pressure from patient’s digitalized arterial pulse waveform analysis without air pressure on patient’s artery. This method can check patient’s blood pressure in a series through converting the continuous arterial pulse waveform into the absolute systolic and diastolic values with pre-defined blood pressure mapping equation from experiments. The experimental results showed that the proposed non-Kortokoff blood pressure measurement method has very good accuracy over 95% compare to commercial tonometers in continuous measurement. Also, the proposed non-Kortokoff blood pressure measurement method can be designed and implemented as a small device since it has no mechanical air pressure compartment, and applied on the u-Healthcare service areas very effectively such as a digital blood pressure checker for usual life blood pressure monitoring along with the medical device for home and hospitals.

Finite-time Synchronization of Delayed Semi-Markov Neural Networks with Dynamic Event-triggered Scheme

Yujing Jin,Wenhai Qi,Guangdeng Zong 제어·로봇·시스템학회 2021 International Journal of Control, Automation, and Vol.19 No.6

In this paper, the finite-time synchronization (FTS) of semi-Markov neural networks (S-MNNs) with time-varying delay is presented. According to the Lyapunov stability theory, a mode-dependent LyapunovKrasovskii functional (LKF) is constructed. Compared with the traditional static event triggered scheme (ETS), a dynamic ETS is adopted to adjust the amount of data transmission and reduce the network burden. By using thegeneral free-weighting matrix method (F-WMM) to estimate a single integral term, a less conservative conclusion is proposed in standard linear matrix inequalities (LMIs). Finally, under the comparison of the static ETS and the dynamic ETS, a simulation example verifies the superiority of this method.