論道德民俗的繼承與解放

Zhiwen Liu 국제아세아민속학회 1997 아세아민속연구 Vol.1 No.-

Wavelet Noise Elimination & Its Application in Acoustic Leak Detection of Fast Reactor Steam Generator

Liu Zhanhui,Niu Xiaodong,Mu Guangyu,Shang Deyi,Xu Zhiwen,Guo Xiaoxin,Pang Yunjie 대한전자공학회 2005 ITC-CSCC :International Technical Conference on Ci Vol.2005 No.4

Acoustic Waves Scattering from a Fluid-Saturated Porous Cylinder

Xu Jing,Liu Jinxia,Cui Zhiwen 한국물리학회 2020 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.77 No.7

This paper reports a study on plane waves in a fluid incident on an infinitely long fluid-saturated porous cylinder. With consideration of both the fluid dynamic viscosity and the inelastic loss of the frame of the porous media, as well as the application-wide frequency of the Biot-Stoll model, the theoretical calculation of acoustic scattering of an acoustic wave at oblique incidence is carried out. The acoustic backscattering spectrum is calculated and used to investigate the influence of the incident angle and the boundary conditions on the scattering characteristics. The results show that the position of the peak on the horizontal coordinate moves to higher frequency as the incident angle is increased. In the soft porous cylinder, whose shear wave velocity is lower than the velocity of the fluid, the change in the backscattering spectrum under the open-pore boundary condition is more obvious than that in the sealed-pore boundary condition. The influence of the incident angle is more obvious in a hard porous cylinder whose shear wave velocity is larger than the velocity of the fluid than it is in a soft porous cylinder.

Three-Dimensional Porous Carbon Nanotube Papers as Current Collector and Buffer for SnO2 Anodes

Xiaogang Sun,Zhiwen Qiu,Long Chen,Manyuan Cai,Jie Wang,Xu Li,Wei Chen,Zhenhong Liu,Hao Tang 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2017 NANO Vol.12 No.11

A novel three-dimensional porous conductive papers have been successfully synthesized via a simple physical route. Multi-walled carbon nanotubes (MWCNTs)@SnO2 composite anode materials are embedded in porous conductive papers. The peculiar structure can accommodate the huge volume expansion of MWCNTs@SnO2 composite anode materials during charge–discharge process. The framework formed by MWCNTs and cellulose can greatly improve the strength, stability and flexibility of the electrode. In addition, the structure successfully prevent the aggregation of SnO2 nanoparticles and collapse of MWCNTs@SnO2 composite electrode, leading to the improvement in electrochemical utilization and stable cyclability. The samples were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM), respectively. The electrochemical properties and application were evaluated by galvanostatic discharge–charge testing and cycling voltammetry. As a result, the MWCNTs@SnO2 composite electrode showed excellent rate performance. The discharge capacity remains about 680mAh g -1 after 100 cycles at 200mA g -1, and even around 300mAh g -1 at 1000mA g -1.

Optimal Strategies for Cooperative Spectrum Sensing in Multiple Cross-over Cognitive Radio Networks

( Hang Hu ),( Youyun Xu ),( Zhiwen Liu ),( Ning Li ),( Hang Zhang ) 한국인터넷정보학회 2012 KSII Transactions on Internet and Information Syst Vol.6 No.12

To improve the sensing performance, cooperation among secondary users can be utilized to collect space diversity. In this paper, we focus on the optimization of cooperative spectrum sensing in which multiple cognitive users efficiently cooperate to achieve superior detection accuracy with minimum sensing error probability in multiple cross-over cognitive radio networks. The analysis focuses on two fusion strategies: soft information fusion and hard information fusion. Under soft information fusion, the optimal threshold of the energy detector is derived in both noncooperative single-user and cooperative multiuser sensing scenarios. Under hard information fusion, the optimal randomized rule and the optimal decision threshold are derived according to the rule of minimum sensing error (MSE). MSE rule shows better performance on improving the final false alarm and detection probability simultaneously. By simulations, our proposed strategy optimizes the sensing performance for each cognitive user which is randomly distributed in the multiple cross-over cognitive radio networks.

Computer simulation of the nonlinear static behavior of axially functionally graded microtube with porosity

Li, Xiaohuan,Wang, Tian,Liu, Fang,Zhu, Zhiwen Techno-Press 2021 Advances in nano research Vol.11 No.4

Static analysis of microstructures, including bending and buckling, is widely practiced in the fabrication and creation of applications such as actuation, sensing, and energy recovery. This article aims to inquire about the static behavior of non-uniform and imperfect microtubes through a numerical solution. Based on the modified couple stress theory, the first-order shear deformation theory and Von-Karman nonlinear theory, and employing the energy conservation method, the linear and nonlinear governing equations are derived. The porosity-dependent material in both ceramic and metal phases makes the functionally graded materials which are varied along tube length, moreover, cross-sections are also considered uniform and nonuniform via three valuable functions. Finally, the linear and nonlinear equations are solved utilizing the generalized differential quadrature method (GDQM) coupled with the numerical iteration method.

Dynamic characteristic parameters identification analysis of a parallel manipulator with flexible links

Chunxia Zhu,Jing Wang,Zhiwen Chen,Bo Liu 대한기계학회 2014 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.28 No.12

This paper presents dynamic parameters identification analysis of a 3-TPT parallel manipulator with flexible links by means of simulationand experiment. The 3-TPT mechanism is described in detail, and the dynamic equations of the regarded mechanism are derivedanalytically based on the Newton’s second law. The dynamic simulation model of parallel manipulator with flexible links is built by theintegration method of virtual prototyping (VP) and finite element analysis (FEA), which forms the flexible multi-body system of parallelmanipulator. Frequency response curves are obtained by applied force on the simulation model, and the stiffness and damping ratio areidentified, respectively, from the simulation results. The strategy has been experimentally tested on an actual 3-TPT parallel manipulator. The compared results show that the errors are very small and reasonable scope, so it is feasible for the integration method used as referenceand basis for dynamic characteristic. Therefore, the integration simulation method provides a theoretical foundation and referencefor dynamic optimal design of parallel manipulator. These analyses and results provide valuable insight into the design and control of theparallel manipulator with flexible links.

New Eu³⁺-activated bismuthate tellurate LiSrBiTeO₆ red-emitting phosphor for InGaN-based w-LEDs

He, Jianyue,Gao, Zhiwen,Liu, Shihua,Jeong, Jung Hyun,Yu, Ruijin,Deng, Bin Elsevier 2018 Journal of luminescence Vol.202 No.-

<P><B>Abstract</B></P> <P>A series of novel Eu<SUP>3+</SUP>-doped LiSrBiTeO<SUB>6</SUB> red-emitting phosphors were prepared by the solid-state reaction method for the first time. Its crystal structure and luminescence properties are investigated. X-ray powder diffraction patterns in combination with the Rietveld method reveal its single phase structure. The phosphor can be efficiently excited by 394 nm and 465 nm light and emits bright red luminescence at 616 nm corresponding to the electric dipole transition <SUP>5</SUP>D<SUB>0</SUB>–<SUP>7</SUP>F<SUB>2</SUB>. The optimal doping concentration of LiSrBi<SUB>1-<I>x</I> </SUB>TeO<SUB>6</SUB>:<I>x</I>Eu<SUP>3+</SUP> is about 40 mol%. The thermal stability of the phosphor was tested by measuring their temperature-dependent emission intensities. The warm white light LEDs was fabricated based on the InGaN-chip. The chromaticity coordinates of fabricated w-LED are (0.344, 0.381). All results indicated that LiSrBiTeO<SUB>6</SUB>:Eu<SUP>3+</SUP> phosphors have potential application as red phosphors in white light emitting diodes.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Experimental Study on Dynamic Tensile Properties of Macro-Polypropylene Fiber Reinforced Cementitious Composites

Guoliang Yang,Jingjiu Bi,Zhiwen Dong,Ying Li,Yi Liu 한국콘크리트학회 2023 International Journal of Concrete Structures and M Vol.17 No.1

Using a high-speed photography system and a split Hopkinson pressure bar, macro-polypropylene fiber reinforced cementitious composites are tested to reveal the effects of the macro-polypropylene fiber volume fraction and loading rate on the dynamic tensile strength and failure mode. We also analyze the functional relationship between the dynamic tensile strength, loading rate, and fiber volume fraction, and study the splitting failure process using digital image correlation technology. The evolution law of the strain and displacement fields of the specimens is obtained, and the effect of the fiber volume fraction on the crack initiation strain value is quantitatively studied. The results show that the appropriate fiber content (1.5–2%) can significantly improve the dynamic tensile strength, while a higher fiber content (2.5%) leads to deterioration of the specimen. Adding macro-polypropylene fiber prevents the specimen from undergoing central tensile fracturing under dynamic loading, and distributes the impact load more evenly, thus improving the ability of the specimen to resist cracking.

glyA Gene Knock-out in Escherichia coli Enhances L-serine Production without Glycine Addition

Ya Zhang,Pei Kang,Shuang Liu,Yujiao Zhao,Zhiwen Wang,Tao Chen 한국생물공학회 2017 Biotechnology and Bioprocess Engineering Vol.22 No.4

In E. coli, glyA encodes for serine hydroxymethyltransferase (SHMT), which converts L-serine to glycine. When engineering L-serine-producing strains, it is therefore favorable to inactivate glyA to prevent L-serine degradation. However, most glyA knockout strains exhibit slow cell growth because of the resulting lack of glycine and C1 units. To overcome this problem, we overexpressed the gcvTHP genes of the glycine cleavage system (GCV), to increase the C1 supply before glyA was knocked out. Subsequently, the kbl and tdh genes were overexpressed to provide additional glycine via the L-threonine degradation pathway, thus restoring normal cell growth independent of glycine addition. Finally, the plasmid pPK10 was introduced to overexpress pgk, serAΔ197, serC and serB, and the resulting strain E4G2 (pPK10) accumulated 266.3 mg/L of L-serine in a semi-defined medium without adding glycine, which was 3.18-fold higher than the production achieved by the control strain E3 (pPK10). This strategy can accordingly be applied to disrupt the L-serine degradation pathway in industrial production strains without causing negative side-effects, ultimately making L-serine production more efficient.