Fabrication of belt-like VO2(M)@C core-shell structured composite to improve the electrochemical properties of VO2(M)

Yifu Zhang,Chongxue Chen,Juecheng Zhang,Ling Hu,Weibing Wu,Yalan Zhong,Yuliang Cao,Xinghai Liu,Chi Huang 한국물리학회 2013 Current Applied Physics Vol.13 No.1

VO2(M) nanobelts encapsulated into carbon coreeshell structured composite (VO2(M)@C) was successfully synthesized by the thermal treatment with the precursor V3O7$H2O@C composite under the inert atmosphere. The as-obtained sample was characterized by XRD, EDS, EA, FT-IR, Raman, SEM and TEM measurements. The core exhibited monoclinic phase VO2(M) and the carbon coated on the surface of VO2(M) was amorphous. The average thickness of carbon was about 18.5 nm. The possible formation mechanism of VO2(M)@C was proposed as that the reaction underwent the solid state reaction by the interface reaction between V3O7 core and carbon shell. Furthermore, VO2(M) and VO2(M)@C composite were explored as the cathode materials to apply in lithium-ion batteries, indicating that the VO2(M)@C composite electrode exhibited the better electrochemical properties than that of pure VO2(M), achieving the aim of improving the electrochemical properties of VO2(M).

Fabrication of Co/Al2O3 Composite Nanofiber via Electrospinning with Tunable Magnetic Properties

Zidong Zhang,Wenjin Zhang,Min Chen,Yuliang Jiang,Rui Tian,Jian Zhang,Runhua Fan 한국섬유공학회 2020 Fibers and polymers Vol.21 No.11

In this paper, Co/Al2O3 composite nanofibers with different Co content are fabricated by electrospinning combinedwith selective reduction. By controlling the Co content in the composite nanofiber, not only the fiber’s morphology, but alsothe magnetic properties can be well adjusted to meet different applications’ requirements. The magnetic hysteresis loops ofcomposite nanofiber show two different types of shape, typical ferromagnetism and wasp-waisted ferromagnetism. Interestingly, the saturation magnetization, which has a close relationship with the content of magnetic component, is notsimply shows an increasing tendency with the increases of Co content in the composite fiber. For the Co content below50 wt%, the Ms value increases with the Co content. After that, the saturation magnetization decreases to a valley value atnear 60 wt% Co content, then increases again. The coercivity also shows the same tendency. The results indicate that thedipolar coupling interaction plays a key role in the magnetic property adjustment of Co/Al2O3 composite nanofiber.

MPPT Adaptive Controller of DC-based DFIG in Resistances Uncertainty

Yuliang Sun,Shaomin Yan,Bin Cai,Yuqiang Wu,Zhongcai Zhang 제어·로봇·시스템학회 2021 International Journal of Control, Automation, and Vol.19 No.8

A coordinated adaptive feedback linearization controller (FLC-A) based on a flux observer for DC-based DFIG to track the maximum power point (MPP) is introduced in this paper. The stator and rotor of DFIG are connected to DC grid directly by two voltage source converters. First, an adaptive controller is used to track the MPP on the system which is decoupled by a single-loop feedback linearization strategy. Meanwhile, the proposed controller can estimate and compensate the changes of stator and rotor resistances caused by physical environment in realtime, and improve the dynamic performance of the system; second, under the persistent excitation condition (PED), a stator flux observer with online resistance estimation in the stationary reference frame is adopted to replace the traditional flux calculation method or flux meter, which increases system reliability. The stability of adaptive control rate and nonlinear observer is proved by Lyapunov theory. Simulations are carried out to prove the effectiveness and robustness of the proposed control strategy.

Investigation of Stereo-dynamic Properties for the Reaction H+HLi by Quasi-classical Trajectory Approach

Yuliang Wang,Jinchun Zhang,Yanlan Jiang,Kun Wang,Mingyu Zhou,Xiaorui Liang 대한화학회 2012 Bulletin of the Korean Chemical Society Vol.33 No.9

Quasi-classical trajectory (QCT) calculations of H+HLi reaction have been carried out on a new potential energy surface of the ground state reported by Prudente et al. [Chem. Phys. Lett. 2009, 474, 18]. The four polarization-dependent differential cross sections have been carried out in the center of mass (CM) frame at various collision energies. The reaction probability for the depletion channel has been studied over a wide collision energy range. It has been found that the collision energy decreases remarkably reaction probability, which shows the expected behavior of the title reaction belonging to an exothermic barrierless reaction. The results are in good agreement with previous RMP results. The P(θr), P(φr) and P(θr, φr) distributions, the k−k'− j' correlation and the angular distribution of product rotational vectors are presented in the form of polar plots. The average rotational alignment factor as a function of collision energy is also calculated. The results indicate that the collision energy has a great influence on the polarization of the product rotational angular momentum vector j'.

Improvement of the electrochemical properties of V_3O_7ㆍH_2O nanobelts for Li battery application through synthesis of V_3O_7@C core-shell nanostructured composites

Yifu Zhang,Min Zhou,Meijuan Fan,Chi Huang,Chongxue Chen,Yuliang Cao,Houbin Li,Xinghai Liu 한국물리학회 2011 Current Applied Physics Vol.11 No.5

V_3O_7ㆍH_2O@C core-shell structured composites have been successfully synthesized using V_3O_7ㆍH_2O nanobelts as the cores and glucose as the source of carbon in the presence of sodium lauryl sulfate (SDS). The as-obtained V_3O_7ㆍH_2O@C core-shell materials were characterized by X-ray powder diffraction (XRD),transmission electron microscopy (TEM), elemental analysis (EA), Fourier transform infrared spectroscopy (FT-IR) and Raman spectrum. The thickness of the carbon shell can be controlled by the hydrothermal reaction time and the quantity of glucose. The surfactants have great influence on fabricating V_3O_7ㆍH_2O@C core-shell composites, which have been discussed in detail. V_3O_7@C composites were subsequently obtained through thermal treatment with V_3O_7ㆍH_2O@C. The electrochemical properties of V_3O_7@C core-shell composites were studied, indicating that the discharge capacity is still 151.2 mAh/g after 45 cycles, which is better than that of pure V_3O_7ㆍH_2O nanobelts.

Investigation of Stereo-dynamic Properties for the Reaction H+HLi by Quasi-classical Trajectory Approach

Wang, Yuliang,Zhang, Jinchun,Jiang, Yanlan,Wang, Kun,Zhou, Mingyu,Liang, Xiaorui Korean Chemical Society 2012 Bulletin of the Korean Chemical Society Vol.33 No.9

Quasi-classical trajectory (QCT) calculations of H+HLi reaction have been carried out on a new potential energy surface of the ground state reported by Prudente et al. [Chem. Phys. Lett. 2009, 474, 18]. The four polarization-dependent differential cross sections have been carried out in the center of mass (CM) frame at various collision energies. The reaction probability for the depletion channel has been studied over a wide collision energy range. It has been found that the collision energy decreases remarkably reaction probability, which shows the expected behavior of the title reaction belonging to an exothermic barrierless reaction. The results are in good agreement with previous RMP results. The P(${\theta}_r$), P(${\phi}_r$) and P(${\theta}_r,\;{\phi}_r$) distributions, the k-k'-j' correlation and the angular distribution of product rotational vectors are presented in the form of polar plots. The average rotational alignment factor <$P_2(j{\prime}{\cdot}k)$> as a function of collision energy is also calculated. The results indicate that the collision energy has a great influence on the polarization of the product rotational angular momentum vector j'.

Experimental and numerical study of the performance and cavitation flow of centrifugal pump with jetting device

BaoLing Cui,Kaicheng Zhu,Yuliang Zhang,Peifeng Lin 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.10

Cavitation is a problem that must be considered when designing and operating a pump. This study proposes an active method using a jetting device to improve its cavitation performance. The influence of jetting flow rate on the external characteristics and cavitation performance of a centrifugal pump is analyzed through numerical simulation and experiment. Results show that the jetting fluid can improve the cavitation performance of a pump and the effect is most evident in the 6 % jetting flow rate. The distribution of entropy generation at the inlet pipe before the impeller shows that jetting flow can increase hydraulic loss in the pipe, thereby diminishing the performance of the centrifugal pump. An analysis of the transient cavitation flow in the centrifugal impeller under 6 % jetting flow rate reveals that the generation, development, and rupture of bubbles deteriorate the flow structure in the passage, thereby resulting in unstable flows and forces.

Influence of Screw Rotors Tip Angle on Mixing Performance for One Novel Twin-screw Kneader

Jing Wei,Dabing Chen,Dongming Zhou,Aiqiang Zhang,Yuliang Yang 한국고분자학회 2015 폴리머 Vol.39 No.3

Twin-screw kneader is an efficient polymer processing equipment. In this paper, the mixing performance of one novel intermeshing counter-rotating twin-screw kneader with different tip angles of the male rotor is simulated using the mesh superimposition technique (MST). Statistical analysis is carried out for the flow field using particle tracking technique, and distributive mixing performance is evaluated using the residence time distribution and segregation scale, while the dispersive mixing performance is estimated using the parameters such as shear rate, stretching rate and mixing index. The results show that the best distributive mixing performance is achieved when the tip angle is 0˚, while the optimal dispersive mixing performance is obtained when the tip angle is 20˚. The results in this paper provide a data basis for the selection of parameters and optimization of the performance for the screw rotors.

An Acid-/Base-Degradable Epoxy Resin Cured by 1,3,5-Triacroylamino- hexahydro-s-triazine Derivative

Lei Wang,Shijing Yan,Lei Zhang,Yuliang Mai,Weihao Li,Hao Pang 한국고분자학회 2021 Macromolecular Research Vol.29 No.7

The degradation and recycling of waste epoxy resin products is an urgent environmental problem. To solve this issue, we use acid-/base-degradable 1,1’,1"- (1,3,5-hexahydro-s-triazine-1,3,5-triyl) tris(3-ethylamino-propan-1-one) (TAHT-EA) as curing agent to introduce the hexahydro-s-triazine (HT) ring structure into the cross-linking network to prepare degradable epoxy resin. Specifically, 1,3,5-triacryloylhexahydro- 1,3,5-triazine (TAHT) and ethylamine quickly complete the Aza-Michael addition reaction at the interface of chloroform and water droplets under the catalysis of water. The FTIR spectra, NMR spectrum and mass spectrum show that mono- and bis-addition products of ethylamine coexist in the product in which the content of the primary addition product reaches 97%. TAHT-EA can be decomposed by acid and base solutions. Through NMR analysis of the degradation products, it can be explained that the degradation mechanisms are different. The breaking of amide bonds and HT rings in acid solution and the cracking of amide bonds in base solution are speculated to be the main mechanisms under these two different circumstances, respectively. We tested the mechanical, thermal and degradation properties of the epoxy resin cured by TAHT-EA, and compared it with the epoxy resin cured by 4,4'-diaminodiphenylmethane and triethylenetetramine. TAHT-EA-cured epoxy resin shows comparable mechanical properties with Young’s modulus up to 2.05 GPa and tensile strength up to 70.9 MPa. What is more, it degrades completely by 1 M H+/OH- solution at 60℃ within 36 h. Nevertheless, it exhibited a relatively low crosslinked density (633 mol/m3) and low heat resistance (the initial decomposition temperature is lower than 205℃). Overall, TAHT-EA cured epoxy resin has the potential to gradually replace traditional thermosetting resin, thereby solving the environmental problems caused by discarded epoxy resin products.

Reachable Set Estimation for Itô Stochastic Semi-Markovian Jump Systems Against Multiple Time Delays

Shaoxin Sun,Xin Dai,Ruipeng Xi,Yuliang Cai,Xiangpeng Xie,Chunhua Zhang 제어·로봇·시스템학회 2022 International Journal of Control, Automation, and Vol.20 No.9

The work deals with these issues of stochastic finite-time boundedness (SFTB), reachable set estimation with input-output finite-time mean square stabilization (IO-FTMSS) for multiple state delayed semi-Markovian jump models subject to uncertainties, stochastic process as well as input constraint. There are few attempts to perform related studies. Firstly, a nonlinear passive control mechanism is designed. Then, a closed-loop model could be acquired. Through stochastic Lyapunov function, these problems of SFTB, reachable set estimation with IO-FTMSS could be solved. In addition, these stability conditions are provided in the framework of linear matrix inequalities. These controller gain matrices, meanwhile, can be derived. At last, this availability of this described strategy can be proved through one simulation.