The influence mechanism of modified calcium bentonite on drying shrinkage of alkali-activated material

Li Wanqiang,Jiang Chunmeng,Li Shuangxi 한양대학교 청정에너지연구소 2023 Journal of Ceramic Processing Research Vol.24 No.2

Volumetric instability is one of the main reasons restricting the engineering application of alkali-activated material (AAM). The aim of this work is to determine the most convenient calcination temperature of calcium bentonite (CB) to reduce thedrying shrinkage of AAM. Five temperature gradients (20 ℃, 150 ℃, 600 ℃, 750 ℃, 900 ℃) and three admixture levels (5%,10%, 15%) were considered. The results show that a calcination temperature of 150 °C and 15% admixture is the optimumtreatment. The compressive strength of the AAM is improved, and the drying shrinkage is substantially reduced. The x-raydiffraction, scanning electron microscope, and mercury intrusion porosimetry tests have shown that calcination at 150 °Cenhanced the interlayer properties for better performance than AAM prepared by dehydroxylation of CB calcined at hightemperatures. The water retention reduces the evaporation of water and generates N-A-S-H gels after dissolution. Causescoarsening of the pore size of the AAM and reduced drying shrinkage.

New dammarane-type triterpenoid saponins from Panax notoginseng saponins

Qian Li,Mingrui Yuan,Xiaohui Li,Jinyu Li,Ming Xu,Di Wei,Desong Wu,Jinfu Wan,Shuangxi Mei,Tao Cui,Jingkun Wang,Zhaoyun Zhu 고려인삼학회 2020 Journal of Ginseng Research Vol.44 No.5

Background: Panax notoginseng saponin (PNS) is the extraction from the roots and rhizomes of Panax notoginseng (Burk.) F. H. Chen. PNS is the main bioactive component of Xuesaitong, Xueshuantong, and other Chinese patent medicines, which are all bestselling prescriptions in China to treat cardiocerebrovascular diseases. Notoginsenoside R₁ and ginsenoside Rg₁, Rd, Re, and Rb₁ are the principal effective constituents of PNS, but a systematic research on the rare saponin compositions has not been conducted. Objective: The objective of this study was to conduct a systematic chemical study on PNS and establish the HPLC fingerprint of PNS to provide scientific evidence in quality control. In addition, the cytotoxicity of the new compounds was tested. Methods: Pure saponins from PNS were isolated by means of many chromatographic methods, and their structures were determined by extensive analyses of NMR and HR-ESI-MS studies. The fingerprint was established by HPLC-UV method. The cytotoxicity of the compounds was tested by 3-(4,5-dimethylthiazol-2-yl)-2,5 -diphenyltetrazolium bromide assay. Results and Conclusion: Three new triterpenoid saponins (1e3) together with 25 known rare saponins (4 e28) were isolated from PNS, except for the five main compounds (notoginsenoside R₁ and ginsenoside Rg₁, Rd, Re, and Rb₁). In addition, the HPLC fingerprint of PNS was established, and the peaks of the isolated compounds were marked. The study of chemical constituents and fingerprint was useful for the quality control of PNS. The study on antitumor activities showed that new Compound 2 exhibited significant inhibitory activity against the tested cell lines.

The Influence of Shaft Eccentricity on the Magnetic Fluid Sealing Performance

Shicong Li,Decai Li,Shuangxi Li 한국자기학회 2023 Journal of Magnetics Vol.28 No.2

This manuscript delves into the impact of shaft eccentricity and diameter on the pressure resistance and magnetic force of a magnetic fluid seal (MFS), through both magnetic circuit analysis method (MCAM) and finite element method (FEM). The study proposes a systematic approach to enhance the performance of eccentric MFS based on MCAM. The results show a near-linear decrease in the pressure resistance of the MFS with increasing eccentricity, with a maximum decline of 65 %. However, the MFS model with a 100 mm shaft diameter renders more precise results in predicting the sealing performance for larger shaft diameters since the pressure resistance decrease remains below 5 % as shaft diameter is increased. The optimal range of pole tooth structure parameters has also been determined. Remarkably, the proposed method affords a precise analysis of the performance of large-diameter eccentric MFS, which is not feasible using two-dimensional axisymmetric magnetic field models.

Dynamic responses and robustness performance to moving boundary of double-stepped cable during deep-sea mining

Li Yilun,Guo Shuangxi,Guo Yucheng,Yu Xiaoqi,Chen Weimin,Song Jixiang 대한조선학회 2023 International Journal of Naval Architecture and Oc Vol.15 No.-

As the exploration and exploitation of deep-sea oil and gas, along with promising polymetallic nodule&sulfides mining, have been developing toward ultra-deep waters, some innovative concepts of marine cable configuration suitable for ultra-deepwater are proposed, such as stepped cable, hybrid cable and double-stepped cable. For deep-water cables with complex configurations, the structural responses become more complicated due to their non-uniform structural properties. Because the distributed buoyancy modules along cable length might introduce more significant local bending segments. Moreover, the impacts of moving boundary, caused by the motions of top vessel and bottom mining vehicle, should be considered. Through combing the finite element simulations with the hydrodynamic models, the dynamic response analysis approach of ultra-deepwater cables is established in this study. Then the double-stepped cable responses, including axial tension, displacement along with the change of overall configurations caused by moving top vessel and bottom mining vehicle, are calculated. Moreover, wave propagation behaviors during cable response are comprehensively examined, and the influences of non-uniform structural properties on cable response and wave propagation are analyzed using the wave propagation theory of structure with axially varying properties based on the Bessel function. The results show that the presented double-stepped cable can provide suitable configurations during the dynamic response, which has good compliance performance and can effectively buffer its response caused by moving boundary excitation. Finally, we found that the response spatial-temporal evolutions present some interesting phenomena, such as the axially non-uniform characteristics lead to non-monotonic changes in response amplitude and wavelength, with local peaks occurring in the low-tension region, owing to the distributed buoyancy modules, along with axiallyvarying and discontinuous structural properties. And, there exists significant mixed effect coming from both standing waves and traveling waves.

Enhanced Multi-sensor Data Fusion Methodology based on Multiple Model Estimation for Integrated Navigation System

Lei Wang,Shuangxi Li 제어·로봇·시스템학회 2018 International Journal of Control, Automation, and Vol.16 No.1

A novel multi-sensor data fusion methodology is presented in this paper with respect to noise with unknown or randomly varying statistics properties and outliers in the SINS/GPS/Odometer integrated navigation system. The proposed methodology combines an adaptive interacting multiple model filtering (AIMM) and federated Kalman algorithm. The former implements dynamic interaction and dynamic change of multiple modes based on the Markov chain process of system models. To achieve the adaptive outlier detection and processing in the measurement signal, modified Kalman filter based on orthogonality of innovation serves as the parallel model filters in the AIMM approach. The advantage of decentralized filter architecture of the latter federated algorithm is flexibility and modularity. It has received considerable attention because of its outstanding fault detection and isolation capability. Experiment results show that the proposed multi-sensor data fusion methodology significantly improves the navigation estimation accuracy and reliability as compared to the federated extend Kalman filter and federated IMM filter approaches.

Structural configurations and dynamic performances of flexible riser with distributed buoyancy modules based on FEM simulations

Chen Weimin,Guo Shuangxi,Li Yilun,Gai Yuxin,Shen Yijun 대한조선학회 2021 International Journal of Naval Architecture and Oc Vol.13 No.1

Flexible risers are usually used as conveying systems to bring ocean resources from sea bed up to onshore. Under ocean environments, risers need to bear complex loads and it is crucial to comprehensively examine riser's configurations and to analyze structural dynamic performances under excitation of bottom vehicle motions, to guarantee structural safe operation and required service lives. In this study, considering a saddle-shaped riser, the influences of some important design parameters, including installation position of buoyancy modules, buoyancy ratio and motion of mining vehicle, on riser's configuration and response are carefully examined. Through our FEM simulations, the spatial distributions of structural tensions and curvatures along of riser length, under different configurations, are compared. Then, the impacts of mining vehicle motion on riser dynamic response are discussed, and structural tolerance performance is assessed. The results show that modules installation position and buoyancy ratio have significant impacts on riser configurations. And, an appropriate riser configuration is obtained through comprehensive analysis on the modules positions and buoyancy ratios. Under this proposed configuration, the structural tension and curvature could moderately change with buoyancy modules and bottom-end conditions, in other words, the proposed saddle-shaped riser has a good tolerance performance to various load excitations.

Characterization of a Novel β-Glucosidase-Like Activity from a Soil Metagenome

Chengjian Jiang,Gefei Ma,Shuangxi Li,Tingting Hu,Zhiqun Che,Peihong Shen,Bing Yan,Bo Wu 한국미생물학회 2009 The journal of microbiology Vol.47 No.5

We report the cloning of a novel β-glucosidase-like gene by function-based screening of a metagenomic library from uncultured soil microorganisms. The gene was named bgl1C and has an open reading frame of 1,443 base pairs. It encodes a 481 amino acid polypeptide with a predicted molecular mass of about 57.8 kDa. The deduced amino acid sequence did not show any homology with known β-glucosidases. The putative β-glucosidase gene was subcloned into the pETBlue-2 vector and overexpressed in E. coli Tuner (DE3) pLacІ; the recombinant protein was purified to homogeneity. Functional characterization with a high performance liquid chromatography method demonstrated that the recombinant Bgl1C protein hydrolyzed D-glucosyl-β-(1-4)-D-glucose to glucose. The maximum activity for Bgl1C protein occurred at pH 8.0 and 42°C using p-nitrophenyl-β-D-glucoside as the substrate. A CaCl2 concentration of 1 mM was required for optimal activity. The putative β-glucosidase had an apparent Km value of 0.19 mM, a Vmax value of 4.75 U/mg and a kcat value of 316.7/min under the optimal reaction conditions. The biochemical characterization of Bgl1C has enlarged our understanding of the novel enzymes that can be isolated from the soil metagenome.

Transverse vibration of the boring bar for BTA deep hole machining under stochastic excitation

Quanbin Zhang,Wu Zhao,Yamin Li,Shuangxi Jing 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.11

Taking the BTA deep hole boring bar as the object of axial flow and axial feed movement, the dynamic characteristics of the fluid-structure coupling boring bar are systematically studied. The influence of complex deformation (bending, torsion, tension, and compression) factors are considered in the derivation of dynamic characteristics. According to the force situation of the BTA deep hole boring bar, the transverse vibration equation of the BTA deep hole boring bar is established. The transverse vibration equation is discretized by Galerkin method, and then its characteristic root, response variance, and spectral density are solved to realize the transverse vibration analysis of the boring bar. Research has found that the correlation between system stability and boring bar speed is no longer monotonous. System stability is positively correlated with the equivalent stiffness and the equivalent shear modulus. There is a negative correlation between system stability and axial force, but it is not significant.

Robust Visual Inertial Odometry Estimation Based on Adaptive Interactive Multiple Model Algorithm

Lei Wang,Shicheng Xia,Hengliu Xi,Shuangxi Li,Le Wang 제어·로봇·시스템학회 2022 International Journal of Control, Automation, and Vol.20 No.10

In this paper, we focus on the problem of motion tracking in unknown environments using visual and inertial sensors, commonly known as visual-Inertial odometer (VIO) tasks. Currently, there are two main types of estimation methods to achieve VIO estimation, the filter-based method and the optimization-based method. We combine multi-state-constraint Kalman filter (MSCKF) algorithm with interactive multi-model algorithm and propose a novel filter-based VIO method. Compared with the VIO algorithm based on extended Kalman filter (EKF), the MSCKF algorithm has less strict probability assumption and better accuracy and consistency. However, traditional EKF and MSCKF algorithms both adopt a single fixed system model, which is difficult to adapt to complex and changeable application scenarios. To solve this problem, we introduce the adaptive multi-model method into the MSCKF algorithm, and combine the two to build an interactive multi-model MSCKF (IMM-MSCKF) algorithm. In the proposed IMM-MSCKF algorithm, several model sub-filters are designed, and their results are fused by transition probability to obtain the optimal state estimation. The common data set KITTI is used to verify the proposed IMM-MSCKF algorithm. Experiment results show that the proposed novel algorithm has better estimation accuracy and robustness compared with other solutions based on multi-state constraint Kalman filter. The IMM-MSCKF algorithm can achieve long-term, high-precision and consistent real-time VIO tasks.

Responses of Soil Bacterial and Fungal Communities to Organic and Conventional Farming Systems in East China

( Hanlin Zhang ),( Xianqing Zheng ),( Naling Bai ),( Shuangxi Li ),( Juanqin Zhang ),( Weiguang Lv ) 한국미생물생명공학회(구 한국산업미생물학회) 2019 Journal of microbiology and biotechnology Vol.29 No.3

Organic farming is considered an effective form of sustainable agricultural management. However, understanding of soil microbial diversity and composition under long-term organic and conventional farming is still limited and controversial. In this study, the Illumina MiSeq platform was applied to investigate the responses of soil bacterial and fungal diversity and compositions to organic farming (OF) and improved conventional farming (CF, applied straw retention) in the rice-wheat rotation system. The results highlighted that the alpha diversity of microbial communities did not differ significantly, except for higher bacterial diversity under OF. However, there were significant differences in the compositions of the soil bacterial and fungal communities between organic and conventional farming. Under our experimental conditions, through the ecological functional analysis of significant different or unique bacterial and fungal taxonomic members at the phyla and genus level, OF enhanced nitrogen, sulfur, phosphorus and carbon dynamic cycling in soil with the presence of Nodosilinea, Nitrospira, LCP-6, HB118, Lyngbya, GOUTA19, Mesorhizobium, Sandaracinobacter, Syntrophobacter and Sphingosinicella, and has the potential to strengthen soil metabolic ability with Novosphingobium. On the other hand, CF increased the intensity of nitrogen cycling with Ardenscatena, KD1-23, Iamia, Nitrosovibrio and Devosia, but enriched several pathogen fungal members, including Coniochaeta, Corallomycetella, Cyclaneusma, Cystostereum, Fistulina, Curvularia and Dissoconium.