A Mild Strategy to Strengthen Three Dimensional Graphene Aerogel for Supporting Sulfur as a Free‐standing Cathode in Lithium–Sulfur Batteries

Yinglin Yan,Haichao Qin,Yiqi Wei,Rong Yang,Yunhua Xu,Liping Chen,Qiaole Li,Mangmang Shi 대한화학회 2018 Bulletin of the Korean Chemical Society Vol.39 No.5

Recently, three dimensional graphene aerogel (3DGA) supported sulfur microparticles was used as a cathode material for lithium?sulfur batteries, which was considered as one of the most promising next generation rechargeable batteries due to its ultra?high theoretical specific capacity (1675 mAh/g). However, the mechanical strength of 3DGA remains an issue for further application. Herein, a strengthened 3DGA (S3DGA) was achieved by soaking in a low concentration ammonia solution at a relative low temperature. Then the S3DGA loaded sulfur (S3DGA?S) was cut into a round piece and directly used as a cathode without additional binders or conductive additives in Li?S batteries. The mechanical strength, microstructure, and electrochemical properties were investigated by compare with a 3DGA prepared without strengthen. The S3DGA?S presented good mechanical strength, excellent capacity retention, and lower electrochemical impedance.

Free vibration analysis of uniform and stepped functionally graded circular cylindrical shells

Haichao Li,Fuzhen Pang,Yuan Du,Cong Gao 국제구조공학회 2019 Steel and Composite Structures, An International J Vol.33 No.2

A semi analytical method is employed to analyze free vibration characteristics of uniform and stepped functionally graded circular cylindrical shells under complex boundary conditions. The analytical model is established based on multi-segment partitioning strategy and first-order shear deformation theory. The displacement functions are handled by unified Jacobi polynomials and Fourier series. In order to obtain continuous conditions and satisfy complex boundary conditions, the penalty method about spring technique is adopted. The solutions about free vibration behavior of functionally graded circular cylindrical shells were obtained by approach of Rayleigh-Ritz. To confirm the dependability and validity of present approach, numerical verifications and convergence studies are conducted on functionally graded cylindrical shells under various influencing factors such as boundaries, spring parameters <i>et al</i>. The present method apparently has rapid convergence ability and excellent stability, and the results of the paper are closely agreed with those obtained by FEM and published literatures.

Low-Frequency Vibration Control of Metro Slab Track Based on Locally Resonant Theory

Chao Li,Sifeng Zhang,Qian Liu,Chong Zhou,Haichao Qin,Luyu Zhang,Minghu Zhai 대한토목학회 2022 KSCE JOURNAL OF CIVIL ENGINEERING Vol.26 No.6

Vibration control has always been one of the research hotspots in the field of urban metro system. Due to the unsatisfactory application effect of traditional vibration damping technology in practice, a novel method, based on the locally resonant theory, was introduced into metro vibration damping system to improve the low-frequency vibration reduction effect. Meanwhile, the new metro vibration reduction slab track was designed. Furthermore, the coupled model of the metro vehicle-slab track was established and verified, and the reduction effect of the new metro slab track on low-frequency vibration under the action of metro vehicles was analyzed. Results show that: 1) The new vibration reduction slab track is really in control of the low-frequency vibration (50 − 100 Hz), and the attenuation effect can reach 10 dB; 2) The new slab track has multiple low-frequency vibration band gaps, which can achieve multi-frequency vibration reduction; 3) The new slab track can reduce the vibration acceleration of the track, which can improve the comfort level of the vehicle. Therefore, the local resonance theory enriches the existing metro vibration reduction design theory and provides a method for the design of the metro vibration control.

Adhesives and Sealants Used in Machinery and Equipment Assembly, Maintain and Repair

Zhai, Haichao,Li, Yinbai,Lin, Xinsong The Society of Adhesion and Interface 2002 접착 및 계면 Vol.3 No.1

In this paper, some idea about the use of Metal and ceramic filled epoxy adhesive, Anaerobic adhesive and RTV silicone in the assembly, maintain and repair of machinery and equipment is given. Many examples which have been successfully used in Chinese industry are introduced: ${\bullet}$ Wear, Abrasion, Corrosion/Erosion Resistance and Metal Rebuilding Worn shafts, Scored Hydraulic Ram, Bearing Housings, Slurry Pumps (Bodies & Impellers), Slide-ways, Heat Exchangers, Cracked Castings and Molds. Leaking Pipes and Tanks. ${\bullet}$ Locking and Retaining Thread, Bearing, Keyways, Bolts, Nuts, Studs, Gears, Collars, Motors. ${\bullet}$ Scaling and Gasketing Flanges, Pipe Joints, Machined surfaces.

Study on Heat Resistance Anaerobic Adhesive Which Expands When Post Cured

Zhai, Haichao,Li, Yinbai,Lin, Xinsong The Society of Adhesion and Interface 2002 접착 및 계면 Vol.3 No.1

In this paper, N,N-m-phenyenedimaleimide (m-PDM), Polyamide Resin (PI) and Metallic dimethacrylate etc. influencing the heat resistance of anaerobic adhesive has been studied, an anaerobic adhesive composition capable of post-cure expansion and $230^{\circ}C$ temperature resistance comprising a multifunctional methacrylate and m-PDM capable of effectuating expansion upon post-cure has been developed. A homogeneous mixture of a monomer and m-PDM are subjected to a first cure heat stage (Room Temperature) wherein a rigid partially-cured plastic is formed and a post-cure heat stage ($150^{\circ}C$) to effectuate permanent expansion of cured adhesive composition.

New constructive model for structures soil

Zhang, Sheng,Li, Haichao,Teng, Jidong Techno-Press 2016 Geomechanics & engineering Vol.11 No.5

A theoretical study of the behavior of structured soils is presented herein. By introducing the effect of soil structure and loading history into the Cam Clay model, a new model was formulated. The concept of differing void ratios was modified to combine structural parameters and the over consolidation ratio, and an evolution law was proposed. Upon introducing the concept of the subloading yield surface, a new two-yield surface model was obtained. The predicted results were compared to the experimental data, demonstrating that the new model provided satisfactory qualitative modeling of many important features of structured soils.

Static Output Feedback Stabilization of a Class of Switched Linear Systems with State Constraints

Qingyu Su,Haichao Zhu,Jian Li 제어·로봇·시스템학회 2018 International Journal of Control, Automation, and Vol.16 No.2

This paper will research the problem of static output feedback (SOF) stabilization of state-constrained switched linear systems via an improved average dwell time method (ADT). Firstly, an improved ADT method is adopted to establish sufficient conditions for SOF of the state-constrained switched linear systems in the form of matrix inequality. It has been shown that this method is less conservative than traditional ADT, which in view of different decay rates of a Lyapunov function related to an active subsystem on the basis of whether the saturations occur or not. Then, a new iterative algorithm is designed to solve the matrix inequality and a SOF controller can be added. In the iterative linear matrix inequality (ILMI) algorithm, it is important not only to overcome the typical bilinear matrix inequality (BMI) problem of SOF, but also to solve the non-convex problem caused by state constraints. Finally, the availability and the applicability of the proposed method is shown by the application of a boost converter.

Analysis of Operation Characteristics of a Diesel Generator Set with Constant‑Power Pulsed Load

Meng Shi,Puyu Wang,Jinquan Wang,Haichao Li,Ye Xu,Kefeng Huang,Jianke Li 대한전기학회 2019 Journal of Electrical Engineering & Technology Vol.14 No.6

To improve the power quality of a diesel generator set with a pulsed load in a microgrid, this paper studied the operation characteristics of the system and proposed pulsed load conditions for an actual project based on test data. For a low average pulse power and a high peak power, a new mathematical model of the pulsed load in diferent operation modes was proposed. Then, a simulation model of the microgrid was established in MATLAB/Simulink, and the operation of the system was studied considering changes in various pulsed load parameters (the peak power Pk, output duty cycle D and switching period Ts). It was verifed by tests that the simulation model is efective and can refect the operation of the system. Based on the simulation model, the operation characteristics of the system with a bivariate pulsed load were studied, and qualifcation conditions for the diesel generator set in an actual project were proposed.

Simulation and Analysis of Mechanical behavior of Groove-shaped Over-Squeezing during Mechanical Ruling

Chaochao Shi,Guangfeng Shi,Guoquan Shi,Haichao Li 한국정밀공학회 2019 International Journal of Precision Engineering and Vol.20 No.7

The single crystal diamond chisel-edge tool is used to machine the 79 g/mm echelle diffraction grating, which is used as the research background. DEFORM-3D finite element software is used to simulate the mechanical ruling grating processing, and the influence of the parameters of the ruling tool on the squeezing force of aluminum film material is obtained. By analyzing the flow law of several sampling points in the groove-shaped over-squeezing region, the slip deformation characteristics of the aluminum film during the groove-shaped over-squeezing are clarified. Moreover, the velocity and stress field of aluminum film are analyzed under groove over-squeezing phenomenon. Therefore, it provides a basis for predicting the phenomenon of groove-shaped over-squeezing in the mechanical ruling grating processing.

Effect of curing mechanism on sulfuric acid corrosion resistance of geopolymer recycled aggregate concrete

Zhenmeng Chen,Hui Liu,Pinghua Zhu,Haichao Li,Tianze Ge,Lei Yang,Chunhong Chen,Yanlong Dong 대한토목학회 2024 KSCE Journal of Civil Engineering Vol.28 No.4

To explore the effect of curing mechanism on the mechanical properties and sulfuric acid corrosion resistance of the geopolymer recycled aggregate concrete (GRAC), the specimens were cured at high temperature (60oC, 80oC) for 6 h, 24 h and 48 h respectively, and then lasted up to 7 d at room temperature. After the curing period was over, the laboratory accelerated simulation test of specimens was carried out by the periodic immersion method: the GRAC specimens (φ 50 × 100 mm) were immersed in the sulfuric acid solution with pH = 1 for 5 d and then dried at room temperature for 24 h, with a total circulation of 90 d. The results showed that after being eroded by sulfuric acid solution, the GRAC specimens cured at 60oC for 48 h had higher compressive strength with 19.9 MPa, lower mass loss rate (only 0.23%) and neutralization depth (5.71 mm) than those under other curing time. The GRAC specimens cured 80oC for 24 h also had a good performance: compressive strength achieved 16.9 MPa and had lower neutralization depth (5.99 mm), which was less affected by sulfuric acid corrosion. However, the GRAC specimens cured at 60oC for 48 h had the better mechanical properties than that cured at 80oC for 24 h. Excessive high temperature curing (80oC) would lead to more voids and microcracks inside GRAC, and destroy the dense structure, thereby reducing mechanical property of concrete. These voids and pores provided more erosion channels for sulfuric acid solution, which accelerated the corrosion rate. From the point of view of energy saving and concrete performance, no more than 60°C of curing temperature is recommended for industrial use.