Parameter Sensitivity Analysis of a New Fabricated Rectangular Tunnel Joint Using Numerical Method

Zhen Huang,Chenlong Zhang,Shaokun Ma,Hai Zhang,Zhang Zhou,Hongzhou Li 대한토목학회 2022 KSCE Journal of Civil Engineering Vol.26 No.2

An assembled rectangular tunnel has the advantages of high space utilization rate and strong urban applicability. This solution has been widely used in urban underground traffic construction. During their construction and operation, the joints are the weakest parts of the structure. The mechanical behavior of joints is closely related to the safety of the tunnel; thus, it is important to use a joint with good mechanical behavior. This study presents a new type of joints for shallow buried assembled rectangular tunnels. To evaluate the effect of design parameters (tenon depth and tenon angle) on the behavior of joints, the finite element method was used. At the same time, the mechanical behavior of rectangular tunnel joint was analyzed and compared with that of a traditional straight joint under the same loading conditions, showing better results. The performance-based engineering (PBE) concept was implemented to evaluate the robustness of rectangular tunnel joints. The results show that if the bolt is placed on the tensile side of the structure, it provides a strong restraining effect on the deformation of the joint. When the tenon depth and angle are 0.8 m and 3.6°, respectively, the overall behavior of the rectangular tunnel joint was improved. The new type of assembled rectangular tunnel joint designed in this study has a good application prospect in a shallow stratum and provides new ideas for the design and construction of such tunnels.

Application of Similitude Rules in Calibrating Microparameters of Particle Mechanics Models

Chenlong Wang,Changsuo Zhang,Xiaodong Zhao 대한토목학회 2018 KSCE JOURNAL OF CIVIL ENGINEERING Vol.22 No.10

Fast determination and calibration of microparameters in particle mechanics models, which can not be directly measured in the standard laboratory tests, is the key to successful simulation. Since the nature of physical similar material test is same as that of microparamter calibration procedure, similitude rules are used to tackle this issue in this paper. Two modeling schemes are designed based on the similitude rules, and the feasibility of the designed schemes is analyzed. The results show that those desired microparameters can be obtained according to the designed schemes when the initial fabric of a model is accurately similar to that of its prototype. Particle resolution (L/D) and particle size distribution (Rmax/Rmin) are the two main factors influencing the fabric similarity between a model and its prototype, and the fabric difference results in the relative errors. When L/D is small and Rmax/Rmin is large, it is difficult to build a model similar to its prototype based on the designed schemes.

Fabrication of diamond/W – Cu functionally graded material by microwave sintering

Chenlong Wei,Jigui Cheng,Mei Zhang,Rui Zhou,Bangzheng Wei,Xinxi Yu,Laima Luo,Pengqi Chen 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.3

A four-layered W/Cu functionally graded material (FGM) (W90% þ Cu10%/W80% þ Cu20%/W70% þ Cu30%/W60% þ Cu40%, wt.% fraction) and a four-layered diamond/WeCu FGM (W90% þ Cu10%/W80% þ Cu20%/W70% þ Cu30%/W55% þ Cu40% þ diamond5%, wt.% fraction) were fabricated by microwavesintering. The thermal conductivity and thermal shock resistance of diamond/WeCu FGM andWeCu FGM were investigated. The morphologies of the diamond particles and different FGMs wereanalyzed using AFM, SEM, EDS, and TEM. The results show that a 200 nm rough tungsten coating wasformed on the surface of the diamond. The density of the tungsten-coated diamond/WeCu FGM, obtainedby microwave sintering at 1200 C for 30 min, was 94.66%. The thermal conductivity of the fourlayereddiamond/WeCu FGM was 220 W$m-1$K-1, which is higher than that of the four-layered W/CuFGM (209 Wm 1 K 1). This indicates that adding an appropriate amount of tungsten-coated diamond tothe high Cu layer W/Cu FGM improves the thermal conductivity of the composite. The diamond/WeCuFGM sintered at 1200 C for 10 min exhibited better thermal shock resistance than diamond/WeCu FGMsintered at 1100 C for 10 min

Structural Dynamic Response of a Frame Tunnel Under Coupled Impact–Explosion Loading

Zhen Huang,Maojiang Qin,Chenlong Zhang,Wenjun Zhang,Zhaojian Hu 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.12

As the main structural bodies of underground facilities such as subway stations, frame tunnel structures play an important role in urban development and construction. In recent years, with the frequent occurrence of explosions after vehicle impacts in tunnels, which have caused severe damage to frame tunnels, the lack of relevant papers makes it necessary to develop a dynamic response analysis of frame tunnels. In this paper, by optimizing the design of an original frame tunnel structure, a dynamic response numerical model of the frame tunnel considering the impact effect of a 3D solidified vehicle and the joint effect is investigated. The deformation trend and damage evolution of the frame tunnel are analysed under different collision masses (1.4, 2.4, 6 and 15 t), collision angles (5, 10, 15 and 75°), collision speeds (60, 80 and 100 km/h), blast delay times (10, 20 and 30 ms) and blast equivalents (50, 100 and 200 kg TNT). This paper improves the active and passive robustness of frame tunnels using both improved operational management and the optimal design of the tunnel structure as a way to ensure the structural safety and functional resilience of frame tunnels.

Influence of Various Cooling and Lubrication Conditions on Tool Wear and Machining Quality in Milling Inconel 718

Zhaojing Gao,Heng Zhang,Min Ji,Chenlong Zuo,Jinsheng Zhang 한국정밀공학회 2024 International Journal of Precision Engineering and Vol.11 No.2

In recent years the global manufacturing industry has put forward the requirements of sustainable production, as well as a higher demand for product quality and productivity. The ever-increasing environmental requirements require cleaner and more environmentally friendly machining techniques to replace traditional immersion lubrication. Inconel 718 alloy has a wide range of applications in aerospace, chemical and power generation, but the difficult-to-cut nature of this alloy poses a great deal of difficulty in its machining. In this paper, supercritical carbon dioxide (scCO2) based cooling lubrication was used to mill Inconel 718 alloy. The scCO2 technology was combined with the minimal quantity lubrication (MQL) technology and the oil-on-water technology (OoW) technology to quantify the effect of different cooling lubrication by analyzing the milling force, milling temperature, surface roughness and tool wear. The experimental results showed that the use of scCO2-based cooling and lubrication conditions significantly reduced the milling forces and milling temperatures and resulted in better machined surface quality. Lower surface roughness values were obtained with scCO2 + OoW cooling compared to dry milling, only scCO2 cooling and scCO2 + MQL cooling.

Effect of Laparoscopic Nerve-sparing Radical Hysterectomy on Bladder Function, Intestinal Function Recovery and Quality of Sexual Life in Patients with Cervical Carcinoma

Chen, Long,Zhang, Wei-Na,Zhang, Sheng-Miao,Yang, Zhi-Hao,Zhang, Ping Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.24

Objective: To investigate bladder and intestinal function recovery and quality of sexual life after laparoscopic nerve-sparing radical hysterectomy (LNRH) for treatment of early invasive cervical carcinoma. Methods: Subjects included patients who underwent radical hysterectomy by laparotomy who were randomly assigned to 2 groups: 30 patients who underwent LNRH and 35 classical laparoscopic radical hysterectomy (LRH). We assessed the patients general clinical information, surgical characteristics, pathological findings, and adjuvant therapies. A urodynamic study was used to assess bladder function. Intestinal function recovery and quality of sexual life were evaluated by questionnaire. Results: No significant differences were found in age, surgery characteristics, pathological findings, adjuvant therapies, and main adverse effects between the 2 groups. The mean duration of the postoperative catheterization (DPC) in group LNRH was shorter than that in group LRH (P < 0.001). The maximum flow rate, maximum cystometric capacity, maximum detrusor pressure and urinary complications in group LNRH were better than those in group LRH. The quality of sexual life evaluated according to the female sexual function index (FSFI) was better in group LNRH than in those who underwent LRH. The intestinal function of patients in group LNRH also recovered better compared with patients in group LRH.

Design and Optimization of a Magnetic Coupling Structure with High Anti-offset for Wireless Power Transfer

Chen Long,Zhang Chunwei,Ben Tong,Nie Heng 대한전기학회 2023 Journal of Electrical Engineering & Technology Vol.18 No.2

As the power transfer efficiency (PTE) is rapidly reduced due to the high offset between the transmitter and the receiver in the wireless power transfer (WPT) system, a Bidirectional Staggered Solenoid Structure (BSSS) with high anti-offset performance was proposed in this paper. Firstly, the factors that affect the PTE are analyzed by establishing a mathematical model of the magnetic coupling structure. Secondly, a parameter optimization method for the traditional flat solenoid coil (FSC) is proposed, which reduces the volume of the magnetic core without reducing the anti-offset ability. Then, the anti-offset performance of the optimized magnetic coupling structure is analyzed and compared with the square, the circle, and the DD (double D) coils structure by three-dimensional (3-D) finite element analysis (FEA). Finally, the anti-offset performance of the structure is verified by a S/S compensated WPT prototype. The PTE is still high when the power transfer distance (PTD) is 164 mm. When the offset distance in X and Y directions increases from 0 to 150 mm, PTE only decreases by 2.62% and 3.71%, respectively.

A large-area free-standing graphene oxide multilayer membrane with high stability for nanofiltration applications

Chen, Long,Li, Yanhui,Chen, Lina,Li, Na,Dong, Chenglong,Chen, Qiong,Liu, Beibei,Ai, Qing,Si, Pengchao,Feng, Jinkui,Zhang, Lin,Suhr, Jonghwan,Lou, Jun,Ci, Lijie Elsevier 2018 CHEMICAL ENGINEERING JOURNAL -LAUSANNE- Vol.345 No.-

<P><B>Abstract</B></P> <P>A flexible and free-standing graphene oxide and nylon 6 (GO@nylon 6) multilayer nanofiltration membrane was prepared by a layer-by-layer assembly process. The combination of electrospinning and electrospraying technique was employed, which can facilely prepare large-area membrane with size of 20 × 30 cm. The mechanical stability of multilayer membrane has enhanced significantly due to the tightly locked structure achieved by nylon 6 nanofibers network. The novel GO@nylon 6–13 multilayer nanofiltration membrane demonstrated a pure water flux up to 11.15 L m<SUP>−2</SUP> h<SUP>−1</SUP> bar<SUP>−1</SUP>, while keeping high organic dye rejection rate (>95% for methylene blue, and >99% for methyl orange). The rejections rate of the Na<SUB>2</SUB>SO<SUB>4</SUB>, NaCl, CuSO<SUB>4</SUB>, and Pb(NO<SUB>3</SUB>)<SUB>2</SUB> were 56.5%, 27.6%, 36.7%, and 18.9%, respectively. Furthermore, GO@nylon 6–13 multilayer nanofiltration membrane also demonstrated a high flux of some common organic solvents (8.4, 5.3, and 0.8 L m<SUP>−2</SUP> h<SUP>−1</SUP> bar<SUP>−1</SUP> for methanol, ethanol, and NMP, respectively), showing excellent chemical stability for separation process in those solvents.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Large-area GO@nylon 6 multilayer nanofiltration membrane was prepared. </LI> <LI> The multilayer structure enhances the mechanical stability. </LI> <LI> The multilayer membrane demonstrates a high water flux. </LI> <LI> The multilayer membrane shows high rejection rate for organic dyes. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>Photograph and cross-section SEM image of GO@nylon 6 multilayer nanofiltration membrane, the inset shows the water contact angle.</P> <P>[DISPLAY OMISSION]</P>