Effect of Sodium Tripolyphosphate on Clay Tolerance of Polycarboxylate Superplasticizer

Hongbo Tan,Yulin Guo,Baoguo Ma,Jian Huang,Benqing Gu,Fubing Zou 대한토목학회 2018 KSCE JOURNAL OF CIVIL ENGINEERING Vol.22 No.8

High fluidity concrete has been widely used in modern civil engineering project to ensure that the highly efficient construction process canbe achieved. Generally, the fluidity can be obtained with the incorporation of superplasticizer system composed of polymers and retarders. Sodium tripolyphosphate (STPP), a commonly used retarder in cement-based material, can obviously increase the dispersion ofpolycarboxylate superplasticizer (PCE), and this has been widely employed in real concrete. However, the effect of STPP on clay toleranceof PCE has not been confirmed until now, and it is still uncertain whether STPP in PCE system has positive or negative effect on workabilityof fresh concrete with poor-quality aggregates containing montmorillonite (Mt) which is one of the most harmful clay minerals. In this study,the effect of STPP on fluidity of cement-Mt paste with PCE has been investigated. The fluidity was tested with mini slump to assess the claytolerance of PCE. The adsorption amount of PCE and STPP in Mt suspension was tested with total organic carbon analyzer and inductivecoupled plasma emission spectrometer to characterize the adsorption behavior. The interlayer spacing was evaluated with X-rayDiffractometer and the structure of intercalated Mt by PCE was characterized with Fourier-transform infrared spectrometer and thermogravimetric analyzer, and these results were used to illustrate the effect of STPP on intercalation of PCE. Finally, the dispersion model wasproposed to reveal the mechanism behind. The results show that STPP can disperse the Mt particles and increase adsorption amount of PCEin Mt suspension, thereby accelerating rather than hindering the intercalation of PCE into Mt. The fluidity of cement-Mt paste with PCESTPPsystem is depended on the added dosage of STPP: with the dosage less than 0.20%, the contribution of STPP to dispersing the cementparticles predominates, hence increasing the fluidity of the paste and improving the clay tolerance; while with the dosage more than 0.20%,the acceleration of the intercalation of PCE resulting from STPP becomes predominant, thereby reducing the fluidity of the paste. This resultcan provide useful experience for the improvement in clay tolerance of PCE in real concrete with poor aggregate containing Mt.

Experimental Study on Residual Mechanical Properties of Bolt-Sphere Joints After a Fire

Hongbo Liu,Zhilun Tan,Zhihua Chen,Zhansheng Liu,Dongyu Liu 한국강구조학회 2018 International Journal of Steel Structures Vol.18 No.3

Through tensile testing of 15 steel bolt-sphere joints and 15 aluminum alloy bolt-sphere joints, infl uencing rules of material type, high temperature and cooling mode on tensile properties of post-fi re bolt-sphere joints were studied, and then failure modes of the joints were determined. According to experimental data, the calculation formula of residual tension capacity of post-fi re bolt-sphere joints was presented. Experimental data indicated that (1) decreased extension on the mechanical properties of aluminum alloy bolt-sphere joints after high temperature in the fi re was signifi cantly higher than that of the steel bolt-sphere joints; (2) when fi re temperature was lower than 800 °C, the tension capacity of steel bolt-sphere joints could be restored by more than 90% after cooling; (3) when fi re temperature was lower than 500 °C, the tension capacity of aluminum alloy bolt-sphere joints could be restored by more than 50% after cooling; (4) bolt-sphere joints could still satisfy the requirement of “strong node and weak member” after a fi re; and (5) material type and fi re temperature were the main factors that infl uenced post-fi re mechanical properties of bolt-sphere joints.

Output Feedback Passification for Switched Discrete-time Nonlinear Systems and Adaptive Control System Design

Hongbo Pang,Shengnan Tan,Shuo Liu 제어·로봇·시스템학회 2022 International Journal of Control, Automation, and Vol.20 No.6

This paper concerns output feedback passification and adaptive output feedback stabilization problems of switched discrete-time nonlinear systems. First, passivity concept is proposed to describe the overall passivity of switched discrete-time nonlinear system without requiring the passivity of active subsystems. Then, the conditions to be passive for such system are provided. Second, the output feedback passification is achieved under a given switching signal, when switched zero dynamics system is passive. Furthermore, adaptive output feedback stabilization problem is solved by using the output feedback passification method. Third, a time-dependent switching signal is designed to guarantee switched zero dynamics system passive. Finally, two examples are presented to verify the effectiveness of the proposed methods.

Rolling Bearing Incipient Fault Detection via Optimized VMD Using Mode Mutual Information

Shuai Tan,Aimin Wang,Hongbo Shi,Lei Guo 제어·로봇·시스템학회 2022 International Journal of Control, Automation, and Vol.20 No.4

The complete failure of the rolling bearing is a deterioration process from the incipient weak fault to the severe fault, thus it is important to alarm when the incipient fault appear. This work presents a novel incipient bearing fault diagnosis framework using mode mutual information (MMI) based fitness function, variational mode decomposition (VMD), and cuckoo search (CS) algorithm. MMI based fitness function is proposed in order to obtain the optimal combinations of the VMD parameters. Therefore, the optimal parameters of VMD can be obtained by CS algorithm using proposed fitness function. Afterwards, a vibration signal is decomposed into a set of modes using the optimal VMD, and the kurtosis value of all modes are calculated. The envelop of the mode with maximum kurtosis value between modes and raw signal is computed as the input vector of the stacked denoised autoencoder (SDAE). Comparisons have been conducted via SDAE to evaluate the performance by using EMD and the fixedparameter VMD. The experimental results demonstrate that the proposed method is more effective in extracting the incipient bearing fault characteristics.

Design and Development of a Single-photon Laser and Infrared Common Aperture Optical System

Wu Hongbo,Zhang Xin,Tan Shuanglong,Liu Mingxin,Wang Lingjie,Yan Lei,Liu Yang,Shi Guangwei 한국광학회 2022 Current Optics and Photonics Vol.6 No.2

A single-photon laser and mid-wave infrared (MWIR) common aperture optical system was designed and developed to detect and range a long-distance civil aviation aircraft. The secondary mirror of the Ritchey-Chretien (R-C) optical system was chosen as a dichroic lens to realize the design of a common aperture system for the laser and MWIR. Point spread function (PSF) ellipticity was introduced to evaluate the coupling efficiency of the laser receiving system. A small aperture stop and narrow filter were set in the secondary image plane and an afocal light path of the laser system, respectively, and the stray light suppression ability of the small aperture stop was verified by modeling and simulation. With high-precision manufacturing technology by single point diamond turning (SPDT) and a high-efficiency dichroic coating, the laser/MWIR common aperture optical system with a φ300 mm aluminum alloy mirror obtained images of buildings at a distance of 5 km with great quality. A civil aviation aircraft detection experiment was conducted. The results show that the common aperture system could detect and track long-distance civil aviation aircraft effectively, and the coverage was more than 450 km (signal-tonoise ratio = 6.3). It satisfied the application requirements for earlier warning and ranging of long-range targets in the area of aviation, aerospace and ground detection systems.

Effect of sodium gluconate on dispersion of polycarboxylate superplasticizer with different grafting density in side chain

Fubing Zou,Hongbo Tan,Yulin Guo,Baoguo Ma,Xingyang He,Yang Zhou 한국공업화학회 2017 Journal of Industrial and Engineering Chemistry Vol.55 No.-

Sodium gluconate is a commonly used retarder, and the incorporation of SG has been accepted as the most efficient way to improve the basic performance of polycarboxylate superplasticizer (PCE) system in real concrete. However, this improvement cannot be always achieved, and the main reason for this uncertainty is because the interaction between PCE and SG has not completely understood. In order to gain deeper insight into this interaction, adsorption behavior and dispersion mechanism of PCE-SG system involved in two kinds of PCE with different grafting density of carboxyl groups in side chain have been investigated. Specifically, the dispersion was assessed with the fluidity of the cement paste, and adsorption behavior was estimated with total organic carbon and zeta potential. The combination between PCE and SG was characterized with conductivity, dynamic light scattering, and X-ray photoelectron spectroscopy. Finally, several models were proposed to illustrate the mechanism behind. The results show that gluconate grafted as side chain of PCE and the increase in length of PEO chain caused by addition of SG can provide contribution to dispersion. Competitive adsorption between SG and PCE would take place to reduce the dispersion, and the declining degree depends on the relative adsorption between PCE and SG. Dispersion of PCE-SG is not only dependent on added dosage of SG, but also decided by molecular structure of PCE. This result provides guidance on how to promote the basic performance of the PCE-retarder system in real engineering practice.

Microwave Signal Spectrum Broadening System Based on Time Compression

Menglong Kong,Zhongwei Tan,Hui Niu,Hongbo Li,Hongpei Gao 한국광학회 2020 Current Optics and Photonics Vol.4 No.4

We propose and experimentally demonstrated an all-optical radio frequency (RF) spectrum broadening system based on time compression. By utilizing the procedure of dispersion compensation values, the frequency domain is broadened by compressing the linear chirp optical pulse which has been multiplexed by the radio frequency. A detailed mathematical description elucidates that the time compression is a very preferred scheme for spectrum broadening. We also report experimental results to prove this method, magnification factor at 2.7, 8 and 11 have been tested with different dispersion values of fiber, the experimental results agree well with the theoretical results. The proposed system is flexible and the magnification factor is determined by the dispersion values, the proposed scheme is a linear system. In addition, the influence of key parameters, for instance optical bandwidth and the sideband suppression ratio (SSR), are discussed. Magnification factor 11 of the proposed system is demonstrated.

Adjust band gap of IATO nanoparticles to obtain desirable optical property by one-step hydrothermal oxidati

Te Hu,Yuchang Su,Ian R. Baxendale,Jiang Tan,Hongbo Tang,Lihua Xiao,Feng Zheng,Ping Ning 한국물리학회 2017 Current Applied Physics Vol.17 No.4

Antimony-tin-doped indium oxide (IATO) as transparent conducting oxide (TCO) exhibits significant optical property on blocking UV and Infrared(IR) for wavelengths less ~400 nm and over ~1400 nm as well as appropriate transmissivity on visible wavelength in our work that can be as an optional idea optical material applying in shielding film or nanocomposite to achieve desired optical application. We have successfully developed an optimal synthesis system which allows for a single hydrothermal oxidation directly synthesizing IATO nanoparticles without high-temperature calcination. These nanoparticles show superior size, crystallinity, agglomeration and are free of intermediates In(OH)3 and InOOH. We also have demonstrated they give scope to desired optical property as a result of an altered IATO band gap energy. We highlight this approach due to the shortened preparation time, the reduced energy consumption and the decreased chemical usage which dramatically save on production costs and protect environment.