Textual properties of Cu–Mn mixed oxides and application for methyl formate synthesis from syngas

Haijun Zhao,Kegong Fang,Fang Dong,Minggui Lin,Yuhan Sun,Zhicheng Tang 한국공업화학회 2017 Journal of Industrial and Engineering Chemistry Vol.54 No.-

Cu–Mn mixed oxides with different calcination temperatures were prepared using ammonia complexing method and evaluated for methyl formate (MF) synthesis from syngas with CaO–ZrO2 as co-catalyst. The influence of calcination temperature on the structure and properties of Cu–Mn mixed oxides was investigated by appropriate characterizations. Cu1.5Mn1.5O4 formed during the calcination of Cu–Mn catalyst at 450 C and played a significant role in the MF synthesis. However, it partially decomposed into CuO and MnO2 when the calcination temperature exceeded 550 C. Results showed that the optimum MF selectivity was obtained on Cu–Mn catalyst calcined at 450 C, and the highest CO conversion was obtained on the Cu–Mn sample with calcination temperature of 550 C. The reaction mechanism of MF synthesis from syngas over Cu–Mn mixed oxides and CaO–ZrO2 co-catalyst was thoroughly studied via typical model reactions, and the nucleophilic addition–elimination reaction mechanism was proposed.

Highly-efficient catalytic combustion performance of 1,2-dichlorobenzene over mesoporous TiO2–SiO2 supported CeMn oxides: The effect of acid sites and redox sites

Haijun Zhao,Weiliang Han,Fang Dong,Zhicheng Tang 한국공업화학회 2018 Journal of Industrial and Engineering Chemistry Vol.64 No.-

High specific surface area CeMn/TiO2–SiO2 catalysts were synthesized and evaluated for the catalytic combustion of 1,2-dichlorobenzene (o-DCB). Mesoporous TiO2–SiO2 supports were prepared by evaporation-induced self-assembly (EISA) method to investigate the promotion of Si on the acid properties of TiO2. Pore structures of TiO2–SiO2 were modulated by controlling the amount of hydrochloric acid during the preparation process of mesoporous supports, and the influence of structures and physicochemical properties of CeMn/TiO2–SiO2 catalysts on the activity and stability of o-DCB catalytic combustion were thoroughly studied. The results showed that Mn cations incorporated into CeO2 fluorite structure caused the formation of more active oxygen species. The active oxygen species and high specific surface area of catalysts played significant roles in o-DCB oxidation reaction. The influence of water on o-DCB catalytic combustion was also studied, and two different observations were obtained at low or high content of water. Due to deposition of Cl species on the surface of catalyst, CeMn/TiO2–SiO2 loses partial activity during o-DCB catalytic combustion, and most of activity could be recovered through Deacon reaction.

A Quick Hybrid Atmospheric-interference Compensation Method in a WFS-less Free-space Optical Communication System

Cui, Suying,Zhao, Xiaohui,He, Xu,Gu, Haijun Optical Society of Korea 2018 Current Optics and Photonics Vol.2 No.6

In wave-front-sensor-less adaptive optics (WFS-less AO) systems, the Jacopo Antonello (JA) method belongs to the model-based class and requires few iterations to achieve acceptable distortion correction. However, this method needs a lot of measurements, especially when it deals with moderate or severe aberration, which is undesired in free-space optical communication (FSOC). On the contrary, the stochastic parallel gradient descent (SPGD) algorithm only requires three time measurements in each iteration, and is widely applied in WFS-less AO systems, even though plenty of iterations are necessary. For better and faster compensation, we propose a WFS-less hybrid approach, borrowing from the JA method to compensate for low-order wave front and from the SPGD algorithm to compensate for residual low-order wave front and high-order wave front. The correction results for this proposed method are provided by simulations to show its superior performance, through comparison of both the Strehl ratio and the convergence speed of the WFS-less hybrid approach to those of the JA method and SPGD algorithm.

Modified Artificial Fish School Algorithm for Free Space Optical Communication with Sensor-Less Adaptive Optics System

Jingtai Cao,Xiaohui Zhao,Zhaokun Li,Wei Liu,Haijun Gu 한국물리학회 2017 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.71 No.10

The performance of free space optical (FSO) communication system is limited by atmospheric turbulent extremely. Adaptive optics (AO) is the significant method to overcome the atmosphere disturbance. Especially, for the strong scintillation effect, the sensor-less AO system plays a major role for compensation. In this paper, a modified artificial fish school (MAFS) algorithm is proposed to compensate the aberrations in the sensor-less AO system. Both the static and dynamic aberrations compensations are analyzed and the performance of FSO communication before and after aberrations compensations is compared. In addition, MAFS algorithm is compared with artificial fish school (AFS) algorithm, stochastic parallel gradient descent (SPGD) algorithm and simulated annealing (SA) algorithm. It is shown that the MAFS algorithm has a higher convergence speed than SPGD algorithm and SA algorithm, and reaches the better convergence value than AFS algorithm, SPGD algorithm and SA algorithm. The sensor-less AO system with MAFS algorithm effectively increases the coupling efficiency at the receiving terminal with fewer numbers of iterations. In conclusion, the MAFS algorithm has great significance for sensor-less AO system to compensate atmospheric turbulence in FSO communication system.

BER Analysis of Coherent Free-Space Optical Communication Systems with a Focal-Plane-Based Wavefront Sensor

Jingtai Cao,Xiaohui Zhao,Wei Liu,Haijun Gu 한국물리학회 2018 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.72 No.5

A wavefront sensor is one of most important units for an adaptive optics system. Based on our previous works, in this paper, we discuss the bit-error-rate (BER) performance of coherent free space optical communication systems with a focal-plane-based wavefront sensor. Firstly, the theory of a focal-plane-based wavefront sensor is given. Then the relationship between the BER and the mixing eciency with a homodyne receiver is discussed on the basis of binary-phase-shift-keying (BPSK) modulation. Finally, the numerical simulation results are shown that the BER will be decreased obviously after aberrations correction with the focal-plane-based wavefront sensor. In addition, the BER will decrease along with increasing number of photons received within a single bit. These analysis results will provide a reference for the design of the coherent Free space optical communication (FSOC) system.

Study on shaped charge cutting of carbon-fiber-reinforced epoxy resin-based composite laminate under prestressing force

Meng Wang,Zhijie He,Kang Zhao,Hong Su,Zekan He,Haijun Xuan 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.9

To realize the explosive separation of carbon-fiber-reinforced composites under a linear-shaped charge, the failure mode of the materials under a linear-shaped charge jet was obtained by combining numerical simulation with experiment. Results show that under the action of the shaped charge jet, the three main failure modes of composite materials are shear failure, delamination failure and tensile failure. Moreover, there are different failure modes of composite materials with different thicknesses. In the early stage of cutting, local fiber peeling occurs on the surface of laminates with different thicknesses under the action of initial jet and stress wave. The thin laminate is sheared directly under the energy of the high-speed jet while the thick laminate first suffers shear failure under the action of the jet. After the end of the jet action, tensile failure occurs under the action of stress wave and, at the same time, spalling occurs along the thickness direction.

Radionuclide identification method for NaI low-count gamma-ray spectra using artificial neural network

Sheng Qi,Shanqiang Wang,Ye Chen,Kun Zhang,Xianyun Ai,Jinglun Li,Haijun Fan,Hui Zhao 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.1

An artificial neural network (ANN) that identifies radionuclides from low-count gamma spectra of a NaIscintillator is proposed. The ANN was trained and tested using simulated spectra. 14 target nuclides wereconsidered corresponding to the requisite radionuclide library of a radionuclide identification devicementioned in IEC 62327-2017. The network shows an average identification accuracy of 98.63% on thevalidation dataset, with the gross counts in each spectrum Nc ¼ 100~10000 and the signal to noise ratioSNR ¼ 0.05e1. Most of the false predictions come from nuclides with low branching ratio and/or similardecay energies. If the Nc>1000 and SNR>0.3, which is defined as the minimum identifiable condition, theaveraged identification accuracy is 99.87%. Even when the source and the detector are covered with leadbricks and the response function of the detector thus varies, the ANN which was trained using nonshieldingspectra still shows high accuracy as long as the minimum identifiable condition is satisfied. Among all the considered nuclides, only the identification accuracy of 235U is seriously affected by theshielding. Identification of other nuclides shows high accuracy even the shielding condition is changed,which indicates that the ANN has good generalization performance.

Smart and versatile biomaterials for cutaneous wound healing

Minxiong Li,Wenzheng Xia,Yi Min Khoong,Lujia Huang,Xin Huang,Hsin Liang,Yun Zhao,Jiayi Mao,Haijun Yu,Tao Zan 한국생체재료학회 2023 생체재료학회지 Vol.27 No.00

The global increase of cutaneous wounds imposes huge health and financial burdens on patients and society. Despite improved wound healing outcomes, conventional wound dressings are far from ideal, owing to the complex healing process. Smart wound dressings, which are sensitive to or interact with changes in wound condition or environment, have been proposed as appealing therapeutic platforms to effectively facilitate wound healing. In this review, the wound healing processes and features of existing biomaterials are firstly introduced, followed by summarizing the mechanisms of smart responsive materials. Afterwards, recent advances and designs in smart and versatile materials of extensive applications for cutaneous wound healing were submarined. Finally, clinical progresses, challenges and future perspectives of the smart wound dressing are discussed. Overall, by mapping the composition and intrinsic structure of smart responsive materials to their individual needs of cutaneous wounds, with particular attention to the responsive mechanisms, this review is promising to advance further progress in designing smart responsive materials for wounds and drive clinical translation.