Information Extraction of Rock Mass structure in Complex Bedrock Mountain Area Based on UAV Oblique Photogrammetry

( Fengyan Wang ),( Mingyu Zhao ),( Fujun Zhou ),( Kai Zhou ),( Qing Ding ),( Ziming Wang ),( Jianping Chen ) 대한지질공학회 2019 대한지질공학회 학술발표회논문집 Vol.2019 No.2

As a new technology developed in recent years, the UAV oblique photogrammetry is of long-distance, non-contact, high-precision and high-density to acquire rapidly 3D spatial data of the object, which has been applied in geological surveying and mapping. Taking the discontinuity information acquisition from Changdu to Linzhi section of Sichuan-Tibet railway in China as an example, 3D model of the survey area is reconstructed by UAV oblique photogrammetry, and the discontinuities are identified and measured in the model by using the 3D mapping system-EPS. Combined with the solution models of discontinuity parameters, the trace length, orientation and opening degree are calculated. Furthermore, the probability distribution of trace length, the dominant grouping of orientation are obtained by probability theory and mathematical statistics. Also, the model display diagram of 3D trace line for long discontinuities, the pole point diagram of orientation, the rose diagram of joint direction and other related maps are drawn by computer graphics so as to describe and cognize the spatial characteristic of complex rock mass structure, which can provide the basic data for stability evaluation of lithological slope and following railway design. The research shows that UAV oblique photogrammetry technology can be applied in discontinuity information extraction of the complex bedrock mountain area compared with the traditional manual measurement, reduces physical input and personal risk, and improve the precision and efficiency of survey, which has a broad application prospects.

Environmental Factors and Adoption of E-Business in China: A Case of International Trading Industry

Jian Wang,Fujun Lai,Dahui Li,Joe Hutchinson 중앙대학교 한국전자무역연구소 2006 전자무역연구 Vol.4 No.2

This study examines environmental factors and adoption of e-Business in China¡'s international trading companies. This paper, which represents a pioneer study of e-business in a China’s industry setting, provides valuable managerial guidance for e-business in China and contributes to the literature with an empirical investigation of e-business in China. A study of 307 Chinese international trading companies resulted in the following conclusions: Firstly, China’s international trading companies are facing increased pressure to implement e-Business. Secondly, high-level e-business implementations remain low in China.

An Anisotropic Failure Criterion for Cross-anisotropic Soils

Hailin Wang,Hong Sun,Xiurun Ge,Fujun Niu 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.9

Strength anisotropy is an important feature closely related to soil microstructure characteristics. A new anisotropic failure criterion, extended from the Ogawa failure criterion, was developed to describe the strength anisotropy of cross-anisotropic soils. Nonlinearization of the failure curves of the Ogawa failure criterion was introduced to account for the nonlinear failure of cross-anisotropic soils in the meridian plane. Meanwhile, an anisotropic strength function based on fabric tensor was theoretically proposed to modify the failure strength under different loading directions and depositional angles. The evolution of the new anisotropic failure criterion in the deviatoric plane was investigated through a series of parametric studies. All of the undetermined parameters in the new criterion can be readily determined in laboratory tests. Compared with experimental results on several types of soils, the new anisotropic failure criterion showed good performance in strength prediction in the deviatoric plane, as well as predicting the peak friction angle. Finally, a linear theoretical relationship on construction of the anisotropic strength function was also elucidated and discussed. The new anisotropic failure criterion proposed in this paper can effectively predict the strength anisotropy of cross-anisotropic soils under different loading directions and depositional angles.

Macro-micro Performances of Granular Materials Considering the Influences of Density and Stress Path under True Triaxial Conditions: A DEM Investigation

Hailin Wang,Hong Sun,Xiurun Ge,Fujun Niu 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.10

The mechanical behaviors of granular materials are dominated by internal structure, which are related to fabric evolution during loading. This study investigated the fabric evolution of granular materials with different densities and stress paths under true triaxial conditions. A series of discrete element numerical simulations with different intermediate principal stress coefficient b were carried out along the constant mean stress p and the constant minor principal stress σ3 stress paths for both loose and dense specimens. The results indicated that the constant-p stress path produced a faster increase in stress ratio than the constant-σ3 stress path at the same b. The effects of specimen density on the peak friction angle are greater than that of stress path. The microscopic analyses revealed that the constant-p stress path facilitates a much more preferential distribution of normal contact force network along the major principal direction. The discrepancies in the peak stress ratio under two stress paths were thus interpreted. The dense specimen will rapidly form a higher anisotropic distribution of the normal contact force network upon shearing, and its anisotropic intensity was almost twice that of the loose specimen at the peak stress state. In addition, a unique relationship between the strong deviatoric fabric ratio and stress ratio was presented. The ratio of the two was approximately 1.0 regardless of stress path, density and b value. Finally, an underlying relationship between the stress components and the whole fabric components at the critical state was confirmed by introducing a new stress tensor. The three principal components (F1, F2 and F3) of the whole fabric tensor can be quantitatively represented with the imposed three principal stress components (σ1, σ2 and σ3) by employing a relationship of F1:F2:F3 = σ10.27:σ20.27:σ30.27. It provides a more comprehensive perspective to analyze the macro-micro performances of granular materials at the critical state.

Numerical Prediction of Unsteady Turbulent Flow and Pressure Fluctuation in an Axial-flow Pump by LES

Guohui Cong,Fujun Wang,Ling Zhang 한국전산유체공학회 2006 한국전산유체공학회 학술대회논문집 Vol.2006 No.5

Influence of thermal treatment on the performance of copper phthalocyanine thin-film transistors

Xueyan Tian,Zheng Xu,Fujun Zhang,Suling Zhao,Guangcai Yuan,Jing Li,Qinjun Sun,Ying Wang 한국물리학회 2010 Current Applied Physics Vol.10 No.1

Organic thin-film transistors (OTFTs) with bottom-gate and bottom-contact configuration based on copper phthalocyanines (CuPc) as active layer were fabricated. The performance of CuPc OTFTs was studied before and after thermal treatment on CuPc layer. The values of the threshold voltage before and after thermal treatment are -6.3 and -5.7 V, respectively. The field-effect mobility values in saturation regime of CuPc thin-film transistors before and after thermal treatment are 0.014 ㎠/Vs and 0.0068 ㎠/Vs,respectively. The experimental results indicate that there is a heavy decay on the mobility of CuPc based OTFTs mostly due to the crystalline morphology change induced by the thermal treatment, and absolute value of the threshold voltage after thermal treatment decreases with the decrease of the CuPc film thickness and the roughness.

Researches on two-phase flows around a hydrofoil using Shan-Chen multi-phase LBM model

Xuelin Tang,Shangyu Yang,Fujun Wang 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.2

In this paper, the Shan-Chen-type multiphase lattice Boltzmann model was proposed to investigate two-phase flows around a hydrofoil. In the model, The Shan-Chen force accounts for the attraction force calculated over nearest neighbours of the pseudopotential function, which is employed to mimic the molecular interactions that cause phase segregation. Firstly, the lattice Boltzmann model was validated by the liquid flows around a hydrofoil by means of comparison of drag coefficients and the Shan-Chen model was validated by the Laplace law. And then aiming at various existing bubbles of different radii preplaced above the hydrofoil leading edge, the evolution of gasliquid two-phase flows was successfully reproduced based on heterogeneous cavitation assumption. The shedding bubbles become smaller and smaller downstream the hydrofoil, and finally collapse behind the tailing edge. The inter-particle forces are analyzed based on the two-phase flow density, and then the corresponding pseudo-velocity distribution is predicted near the phase interface. Then the attached cavitating flows is studied based on homogeneous cavitation assumption. It can be concluded that the attached cavitation occurs and evolves under some reasonable conditions. It can be found that that a small change in the velocity or pressure will bring great influence on the bubble size. All the above-analyses demonstrate that Shan-Chen multiphase model can capture well the inter-phase force and can be treated as an alternative potential approach for predicting cavitating flows.

Crashworthiness of Thermoplastic Woven Glass Fabric Reinforced Composite Tubes Manufactured by Pultrusion

Mingrui Liu,Biao Yan,Xiongqi Peng,Fujun Peng,Lidong Wang 한국섬유공학회 2020 Fibers and polymers Vol.21 No.2

In this paper, crashworthiness of thermoplastic woven fabric reinforced composite tubes were investigated. Thermoplastic composite tubes with various length (40 mm and 80 mm) and fiber yarn orientation with respective tolengthwise (0 o/90 o, 15 o/75 o, 30 o/60 o and 45 o/45 o) were manufactured by pultrusion and welding from home-made woven glass fabric/PP prepreg sheets. Quasi-static axial compressive tests of the composite tubes were performed under various temperatures (298 K, 358 K, 398 K and 453 K). Three crushing modes were observed: progressive folding, splaying and weld seam cracking. The influence of fiber orientation, tube length-diameter ratio and testing temperature on the peak load, mean load, specific energy absorption and crush efficiency were investigated. The results show that the peak load is controlled by fiber orientation and testing temperature. The mean force, specific energy absorption and crush efficiency are related to the three mentioned factors. Both fiber orientation and testing temperature have obviously influence on crushing modes of thermoplastic composite tubes. Length-to-diameter ratio also plays a role in crushing modes when the testing temperature is higher than the melting point of the resin.

Development of a Novel 3-DOF Suspension Mechanism for Multi-Function Stylus Profiling Systems

Jia Tian,Yanling Tian,Zhiyong Guo,Fujun Wang,Dawei Zhang,Xianping Liu,Bijian Shirinzadeh 한국정밀공학회 2016 International Journal of Precision Engineering and Vol.17 No.11

This paper proposes a novel 3-DOF suspension mechanism for multi-function stylus profiling systems. Incorporating an electromagnetic force actuator, the 3-DOF suspension mechanism provides a controlled loading force. For reasons of the thermal and mechanical stability, a triangular flexure structure is utilized to support the stylus. The stiffness matrix method is used to establish the analytical stiffness model of the 3-DOF suspension mechanism. Considering the 3-DOF suspension mechanism as a 3-DOF lumped-mass-spring system, the dynamic model is established. Finite element analysis (FEA) is used to validate the established static and dynamic models of the 3-DOF suspension mechanism. A prototype is fabricated and experimental tests are carried out to characterize the mechanism’s performance. The results show that the 3-DOF suspension mechanism provides a controlled force in a range of up to 10 mN and has a working range in excess of 10 μm with a first natural frequency of 342 Hz in Z axis, indicating good capability for multi-function measurements at the micro/nano scale.

Comparison of image masking methods for pump impeller blade region PIV experiments

Xiaodong Liu,Tingting Yan,Qiang Zhong,Zhuqing Liu,Fujun Wang,Yaojun Li,Wei Yang 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.6

Due to the blade reflection effect when applying the PIV technology to the internal flow field measurement of rotating machinery, the blade area requires special treatment. In this paper, zero-value, particle image, random number, and mean-value masking methods are compared and analyzed based on particle images from the PIV challenge and rotating impeller. The peak significance and coordinates deviations are used as the masking effect evaluation criteria. The results indicate that an increase in the interrogation window masking area proportion causes a weakening of the PIV calculation particle cluster displacement peak value. The peak position is shifted, which leads to the wrong velocity vector. The masking area proportion should not be higher than 0.7, 0.5, 0.19, and 0.22 for mean-value, random number, zero-value, and particle image masking methods, respectively. The results show that flow field calculation results near the blade boundary are more accurate for mean-value masking.