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ZHANG Yongzhen,SUN Gesen,SUN Lemin,LIU Weimin,SHANGGUAN Bao,Chen Yue 한국트라이볼로지학회 2002 한국트라이볼로지학회 학술대회 Vol.2002 No.10
Based on 3-D surface morphology measurements of C.G. irons, the fractal analyses were made on relationship between dry sliding surface morphology and the fractal dimension. It is revealed that the values of fractal dimensions (Df) of sliding surfaces are in the range between 1-2, which are closely related to the surface morphologies. With the increase in depths of grooves or pits, the Df values increase. At the same lime, the increases in densities of the grooves also cause the Df values to increase. At last, relationship among Df and friction coefficient as well as wear rate is discussed.
An Efficient Blind Detection Algorithm of Median Filtered Image
Yongzhen Ke,Fan Qin,Weidong Min,Qiang Zhang 보안공학연구지원센터 2015 International Journal of Hybrid Information Techno Vol.8 No.1
Due to the significant advances of digital photography and the availability of many powerful photo editing tools, it becomes easier to create forgery images by non-professional users. Median filtering that is usually applied to erase the forensically significant fingerprints has recently received increased attention. In this paper, we present an effective blind forensic algorithm to detect the median filtering manipulation. First, the median filtered residual (MFR) is generated by computing the difference between a testing image and a median filtered version of itself. Then, three feature sets including histogram, autocorrelation and gradient are extracted from the median filter residual. Last, those features are fetched into support vector machine (SVM) for training and classification. Our experimental results demonstrate that our proposed forensic method achieves not only better detection rate but also lower computational complexity compared with other existing median filtering detection methods. Our proposed forensic method also can locate local median filtering of image effectively.
Yongzhen Wang,Borui Wang,Dandan Xu,Meng Zhang,Xiaohua Zhang,Deguo Wang 대한수의학회 2022 Journal of Veterinary Science Vol.23 No.4
Background: Due to the unavailability of an effective vaccine or antiviral drug against the African swine fever virus (ASFV), rapid diagnosis methods are needed to prevent highly contagious African swine fever. Objectives: The objective of this study was to establish the ladder-shape melting temperature isothermal amplification (LMTIA) assay for the detection of ASFV. Methods: LMTIA primers were designed with the p72 gene of ASFV as the target, and plasmid pUC57 was used to clone the gene. The LMTIA reaction system was optimized with the plasmid as the positive control, and the performance of the LMTIA assay was compared with that of the commercial real-time polymerase chain reaction (PCR) kit in terms of sensitivity and detection rate using 200 serum samples. Results: Our results showed that the LMTIA assay could detect the 104 dilution of DNA extracted from the positive reference serum sample, which was the same as that of the commercial real-time PCR kit. The coincidence rate between the two assays was 100%. Conclusions: The LMTIA assay had high sensitivity, good detection, and simple operation. Thus, it is suitable for facilitating preliminary and cost-effective surveillance for the prevention and control of ASFV.
Wang Zhong,Yongzhen Gu,Shunji Zhang,Qinggang Zhang 한국항공우주학회 2024 International Journal of Aeronautical and Space Sc Vol.25 No.2
The membrane reflector antenna (MRA) possesses significant advantages, such as being light in weight and having a large storage ratio. As a result, it is considered one of the critical forms of space-borne antennas. However, the MRA faces a challenge in that it is easily impacted by thermal loads in space, and there is a lack of effective shape adjustment means. To address this issue, a bidirectional adjustment method has been proposed utilizing electrostatic forces and boundary cable forces. Firstly, the mechanical analysis model of the MRA, including the cable-membrane-truss structure, is constructed based on the energy variation principle. Then the calculation formula of electrostatic forces has been deduced considering the change in the distance between the membrane reflector surface and the membrane control surface. The update process of electrostatic forces has also been presented. Finally, an optimization model of the shape adjustment of the MRA has been established, with electrode voltages and boundary cable forces as design variables and the surface accuracy of the membrane reflector as the optimization goal. Simulation examples have been conducted under three types of temperature loads, and a 10:1 scaled experimental prototype has been used to verify the effectiveness of the shape adjustment method.
Mechanical simulation for the bending process of the AMOLED panel pad
Wu Di,Jia Yongzhen,Liao Dunming,Zhang Bo,Liu Chen,Wang Ning,Peng Wenjing,Huang Liting 한국정보디스플레이학회 2023 Journal of information display Vol.24 No.2
Panel pad bending is a critical process to improve the screen-to-body ratio of an active-matrix organic light-emitting diode (AMOLED) panel. The failure analysis of the metal wirings is the key to ensure the reliability of signal transmission when the pad be bent to the back of the panel. In the present work, the sub-modeling technique combined with the periodic boundary condition was used to simulate the stress distribution of the bending area of the pad. The progressive failure of bent metal wirings was investigated by the extended finite element method. It is proved to be rational to prevent the wirings damage if the interlayer dielectric is replaced by an organic layer. In order to reduce stress of metal wirings, it is a measure to replace the original ultraviolet (UV) curable adhesive with a higher-modulus UV adhesive. The simulated results also show that rectangular perforations can avoid the stress concentration caused by the holes compared with circular perforations. For better stress distribution of metal wirings, it is necessary to increase the lengths of the rectangular holes and decrease the widths of that to a certain extent, which is helpful for restraining crack propagation by means of low-stress zones and holes.
SOOT DEVELOPMENT IN AN OPTICAL DIRECT INJECTION SPARK IGNITION ENGINE FUELED WITH ISOOCTANE
Fangxi Xie,Miaomiao Zhang,Yongzhen Wang,Yan Su,Wei Hong,Peng Cheng 한국자동차공학회 2021 International journal of automotive technology Vol.22 No.2
To better understand the formation and evolution processes of soot, the two-color laser induced incandescence diagnostic method was applied on a single cylinder optical direct injection spark ignition engine. Soot volume fraction was measured, and soot distribution was imaged as cyclic fuel quantity changes. The results show that 45.5 mg/cycle generates the most soot at the same measure plane. Pool fire dominates the formation of soot in the tested engine and generates more soot on the top surface of the piston near the injector. In-cylinder soot increases until 42°CA ATDC and then reduces due to oxidation. Pool fire continues through the expansion stroke till 52°CA ATDC, and then soot cloud gathers near the 10 mm plane. After 82°CA ATDC, in-cylinder soot basically in equilibrium, and residual soot moves follow the in-cylinder flow randomly and evenly distributes within the whole combustion chamber. With increasing cyclic fuel quantity, particles number concentration gradually increases and their distribution present dual-peak shape. In detail, 45.5 mg/cycle emits the most accumulation mode particles while 52 mg/cycle emits the most nucleation mode particles.
High-Conductivity SiO2-Matrix B-Doped Si-NC Thin Films by Following Ion-Beam Treatment
Junjun Huang,Weiyan Wang,Jie Yang,Yongzhen Tan,Wei Chen,Tianyu Ge,Yajun Zhang,Min Gao,Zhenming Chen 대한금속·재료학회 2016 ELECTRONIC MATERIALS LETTERS Vol.12 No.6
In this work, further ion-beam was performed on SiO2-matrix B-doped Si-NC (SBC) thin films in order to enhance conductivity. The effect of ionbeamtype on the electrical properties of SBC thin films was investigatedsystematically. The results indicated that the conductivities of SBC thinfilms were significantly improved by both argon and hydrogen ion-beamtreatments, and the higher the hydrogen ion ratio, the higher theconductivity of SBC thin films. The conductivity of SBC thin films wasincreased from 1.82 × 10−6 S/cm to 3.2 × 10−3 S/cm with followinghydrogen-ion-beam treatment. The change in conductivity of SBC thinfilms was most possibly resultant from the ion-beam treatment facilitatingthe formation of higher superficial order and lower defects. An alternativemethod was proposed to prepare high-conductivity SBC thin films, whichmay be applied to other heterogeneous thin films.
Dry Sliding Tribological Characteristics of SiC Particle-reinforced Aluminum Composites in Brakes
CHEN Yue,DAI Baolin,SHANGGUAN Bao,ZHANG Yongzhen,SUN Lemin 한국트라이볼로지학회 2002 한국트라이볼로지학회 학술대회 Vol.2002 No.10
The dry sliding tribological characteristics were investigated using SiC particle-reinforced aluminum composites against semi-metallic frictional materials. The experimental results have indicated that, whether under the condition of continuous braking or not, the wear rates of SiC particle reinforced composites are much less than that of gray cast iron which is used as one of the common brake disk materials. At the same time, their frictional coefficients are about the same.