Local and Distortional Interaction Buckling of Cold-formed Thin-Walled High Strength Lipped Channel Columns

Lihua Huang,Wenbin Yang,Tingwei Shi,Jiting Qu 한국강구조학회 2021 International Journal of Steel Structures Vol.21 No.1

In this paper, a series of axial compression tests were conducted on lipped channel columns constructed from cold-formed high strength Grade G550 steel sheet of thickness of 1 mm in order to investigate the local and distortional interaction buckling performance. The failure modes, ultimate loads and load–displacement curves of the specimens were reported and analyzed. The experiment revealed the deformation mechanism of specimens failing in local-distortional interaction or distortional mode. Besides, a fi nite element model was developed to predict the buckling performance of the specimens. The eff ect of diff erent imperfection shapes and material models on numerical results was investigated so that the reasonable fi nite element analysis can be carried out. It was found that the local buckling mode with an odd number of waves as the initial imperfection can produce practical deformation process. Meanwhile, the material model of Ramberg–Osgood can be applied for the nonlinear fi nite element analysis of the specimens. The parametric analysis was also performed to study the relationship between the sensitivity of specimens to local and distortional imperfections as well as the variation of bearing capacity with the geometric size. It was found that the lip width has great infl uence on the bearing capacity of specimens because of the signifi cant restriction of lip on distortional deformation.

Prediction of long-term compressive strength of concrete with admixtures using hybrid swarm-based algorithms

Lihua Huang,Wei Jiang,Yuling Wang,Yirong Zhu,Mansour Afzal 국제구조공학회 2022 Smart Structures and Systems, An International Jou Vol.29 No.3

Concrete is a most utilized material in the construction industry that have main components. The strength of concrete can be improved by adding some admixtures. Evaluating the impact of fly ash (FA) and silica fume (SF) on the longterm compressive strength (CS) of concrete provokes to find the significant parameters in predicting the CS, which could be useful in the practical works and would be extensible in the future analysis. In this study, to evaluate the effective parameters in predicting the CS of concrete containing admixtures in the long-term and present a fitted equation, the multivariate adaptive regression splines (MARS) method has been used, which could find a relationship between independent and dependent variables. Next, for optimizing the output equation, biogeography-based optimization (BBO), particle swarm optimization (PSO), and hybrid PSOBBO methods have been utilized to find the most optimal conclusions. It could be concluded that for CS predictions in the long-term, all proposed models have the coefficient of determination (R²) larger than 0.9243. Furthermore, MARS-PSOBBO could be offered as the best model to predict CS between three hybrid algorithms accurately.

Characterization and expression analysis of BcAMT1;4, an ammonium transporter gene in flowering Chinese cabbage

Lihua Zhong,Xinmin Huang,Yunna Zhu,Erfeng Kou,Houcheng Liu,Guangwen Sun,Riyuan Chen,Shiwei Song 한국원예학회 2019 Horticulture, Environment, and Biotechnology Vol.60 No.4

Ammonium (NH 4+ ) is generated during many endogenous metabolic processes in the leaves of plants, and there is increasing evidence that ammonium transporters (AMTs) play important roles in NH 4 + transmembrane transport and distribution. However, the expression of diff erent AMT genes is tissue-type specifi c and their functions diff er. Information about AMT genes and their expression under diff erent environmental conditions in fl owering Chinese cabbage ( Brassica campestris L.) is currently limited. Here, we isolated and characterized an AMT gene, BcAMT1;4 , in fl owering Chinese cabbage. BcAMT1;4 was localized to the plasma membrane and complemented NH 4+ transport in NH 4+ uptake-defi cient yeast. The highest expression levels of BcAMT1;4 were detected in the fl owers and leaves of fl owering Chinese cabbage. The expression of BcAMT1;4 was induced by nitrogen defi ciency and signifi cantly inhibited by the reapplication of NH 4+ (NH 4 Cl or NH 4 NO 3 ). In contrast, when plants pre-cultured in nitrate were transferred to an NH 4+ nutrient solution, BcAMT1;4 expression was signifi cantly enhanced. BcAMT1;4 exhibited a diurnal expression pattern, with higher expression levels during the light period than during the dark period, and a peak expression at the later stage of the light period. Knowledge of AMT genes in fl owering Chinese cabbage will lay a foundation for enhancing our understanding of the functional roles of diff erent AMT members in the regulation of its growth by NH 4+ , as BcAMT1;4 seems to play an important role in leaf NH 4+ transport.

Vibration Control of Soil-structure Systems and Pile-soil-structure Systems

Lihua Zou,Leiqing Fang,Kai Huang,Liyuan Wang 대한토목학회 2012 KSCE JOURNAL OF CIVIL ENGINEERING Vol.16 No.5

The purpose of this paper is to investigate the influence of Soil-Structure Interaction (SSI) and Pile-Soil-Structure Interaction (PSSI) on vibration control effect. Assuming the ground as an isotropic elastic half space and the soil around the foundation as a horizontal and rotational spring-dashpot system, a SSI model for buildings with rigid shallow foundations is established. Based on Penzien model, a PSSI model for structures with pile-foundations is also set up. Then, after the motion and control equations of the SSI system and PSSI system are derived, the influences of SSI and PSSI on vibration control are investigated. Important parameters of soil and structures are studied. Numerical results show that the SSI and PSSI have an obvious influence on the control effect of structures. Parameters such as shear-wave velocity, embedded depth of soil and stiffness of superstructure and pile, play a significant role in vibration control. The influences of SSI and PSSI mainly depend on characteristics of the upper soil layer, hence, the SSI influence on buildings with rigid foundations is more obvious than that of PSSI on buildings with pile foundations.

Deformation Characteristics and Constitutive Model of Construction and Demolition Waste Stabilized with Alkali-Activated Fly Ash

Lihua Li,Chang Huang,Henglin Xiao,Zhiming Chao,Haoqi Zhang 대한토목학회 2024 KSCE Journal of Civil Engineering Vol.28 No.4

This study employed triaxial compression tests to investigate the deformation characteristics and damage evolution of construction and demolition waste (C&D) stabilized with alkali-activated fly ash (FA). Furthermore, the study explored the mechanisms of microcracks initiation, propagation, and the stress-strain behavior of stabilized C&D under varying stress conditions. A strain-softening damage model was employed to investigate the mechanism of damage evolution in the specimens. The test results revealed that the internal damage process of the stabilized recycled concrete aggregate (RCA) exhibited five stages: elastic recovery, damage initiation, damage acceleration, damage deceleration, and damage completion. The confining pressure had a significant influence on the deformation characteristics of the specimens. Additionally, the deformation characteristics of the stabilized C&D and rock materials exhibited remarkable similarities. By employing a model of rock strain softening and intrinsic structural damage the damage evolution trends and the equation of the intrinsic structure of the main component RCA-FA. The results demonstrated a good agreement between the test data and the predictions of the proposed constitutive model.

Experimental Investigation on Damage Behavior of Polypropylene Fiber Reinforced Concrete under Compression

Lihua Xu,Biao Li,Xiaoxiao Ding,Yin Chi,Changning Li,Biao Huang,Yuchuan Shi 한국콘크리트학회 2018 International Journal of Concrete Structures and M Vol.12 No.7

This paper presents an experimental investigation on the stress–strain behavior and the damage mechanism of polypropylene fiber reinforced concrete (PFRC) under monotonic and cyclic compression. Fifty-four specimens for different fiber volume fractions and aspect ratios were tested. Acoustic emission (AE) technique was used to monitor the damage progression. The damage mechanism of concrete was analyzed based on the AE parametric analysis. The results show that the incorporation of polypropylene fiber (PF) has a positive effect on the monotonic and cyclic behaviors of concrete, especially for the post-cracking branch. The toughness and ultimate strain are enhanced and the performance degradation in terms of elastic stiffness and strength is alleviated by the addition of PF. However, PF has little influences on the plastic strain, and the damage process of concrete is mainly driven by the envelope strain. The effect of fiber volume fraction on the cyclic behavior of concrete shows more pronounced than that of aspect ratio. In addition, it is found from AE results that the damage, closely related to AE events, has a quick evolution just after the peak stress, with the AE hits having a concentrated release. The total amount of AE hits increases with increasing fiber volume fraction due to fiber pullout and sliding, while the concrete with fiber aspect ratio of 280 reaches the largest amount. Meanwhile, as substantiated by AE, the failure of PFRC shows an obvious shear mode, with shear cracks dominating the damage progression. Finally, a damage elasto-plastic model is developed to predict the monotonic and cyclic responses of PFRC and the prediction yields a fairly close estimation with experimental results.

Synthesis and Characterization of Folic Acid Labeled Upconversion Fluorescent Nanoprobes for in vitro Cancer Cells Targeted Imaging

Ming Huang,Lijun Wang,Xiaojuan Zhang,Jin Zhou,Lihua Liu,Yuefang Pan,Bin Yu,ZHANGSEN YU 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2017 NANO Vol.12 No.5

Upconversion nanoparticles (UCNPs) are widely used in the field of biomedicine, such as biosensing, cell labeling and medical multimodal imaging because of their unique optical properties. In this paper, we demonstrated the synthesis of polyethylenimine-modified NaLuF4:Yb,Er (RE = Lu 0.78, Yb 0.18, Er 0.02) UCNPs in three different solvents, such as water, ethylene glycol and diethylene glycol. The as-prepared UCNPs were characterized and the experimental results showed that the UCNPs synthesized in ethylene glycol had excellent properties. The obtained UCNPs in ethylene glycol had the smallest particle size and uniform size distribution, and the pure cubic phase of crystallization and Dynamic light scattering and particle dispersion index (DLS/Pdi) were the smallest. What's more, the upconversion fluorescence intensity was 7 and 52 times greater than that of UCNPs synthesized in diethylene glycol and water, respectively. In addition, the factors of reaction solvent that had an impact on the particle size, morphology, crystalline phase, DLS and upconversion fluorescence intensity of the synthesized UCNPs were discussed. Moreover, in order to obtain the targeted nanoprobe, we used an EDC/NHS covalent coupling method to modify folic acid to the NaLuF4:Yb,Er/PEI UCNP surface. The NaLuF4:Yb, Er/PEI–FA upconversion fluorescent nanoprobes had low cytotoxicity and were suitable for the application in HeLa cells targeted fluorescent imaging.

New evaluation methods for conceptual design selection using computational intelligence techniques†

Hong-Zhong Huang,Yu Liu,Yanfeng Li,Lihua Xue,Zhonglai Wang 대한기계학회 2013 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.27 No.3

The conceptual design selection, which aims at choosing the best or most desirable design scheme among several candidates for the subsequent detailed design stage, oftentimes requires a set of tools to conduct design evaluation. Using computational intelligence techniques, such as fuzzy logic, neural network, genetic algorithm, and physical programming, several design evaluation methods are put forth in this paper to realize the conceptual design selection under different scenarios. Depending on whether an evaluation crite-rion can be quantified or not, the linear physical programming (LPP) model and the RAOGA-based fuzzy neural network (FNN) model can be utilized to evaluate design alternatives in conceptual design stage. Furthermore, on the basis of Vanegas and Labib’s work, a multi-level conceptual design evaluation model based on the new fuzzy weighted average (NFWA) and the fuzzy compromise decision-making method is developed to solve the design evaluation problem consisting of many hierarchical criteria. The effectiveness of the proposed methods is demonstrated via several illustrative examples.

Estimation of splitting tensile strength of modified recycled aggregate concrete using hybrid algorithms

Yirong Zhu,Lihua Huang,Zhijun Zhang,Behzad Bayrami 국제구조공학회 2022 Steel and Composite Structures, An International J Vol.44 No.3

Recycling concrete construction waste is an encouraging step toward green and sustainable building. A lot of research has been done on recycled aggregate concretes ( s), but not nearly as much has been done on concrete made with recycled aggregate. Recycled aggregate concrete, on the other hand, has been found to have a lower mechanical productivity compared to conventional one. Accurately estimating the mechanical behavior of the concrete samples is a most important scientific topic in civil, structural, and construction engineering. This may prevent the need for excess time and effort and lead to economic considerations because experimental studies are often time-consuming, costly, and troublous. This study presents a comprehensive data-mining-based model for predicting the splitting tensile strength of recycled aggregate concrete modified with glass fiber and silica fume. For this purpose, first, 168 splitting tensile strength tests under different conditions have been performed in the laboratory, then based on the different conditions of each experiment, some variables are considered as input parameters to predict the splitting tensile strength. Then, three hybrid models as GWO-RF, GWO-MLP, and GWO-SVR, were utilized for this purpose. The results showed that all developed GWO-based hybrid predicting models have good agreement with measured experimental results. Significantly, the GWO-RF model has the best accuracy based on the model performance assessment criteria for training and testing data.

Research on High Precision Servo System of Actuator Based on PID Parameter Stability Domain Under Mixed Sensitivity Constraint

Zheng HaoXin,Huang MingHui,Zhan LiHua,Zhu YanMei,Liu PeiYao 대한전기학회 2021 Journal of Electrical Engineering & Technology Vol.16 No.3

In the PID controller design, three sensitivity functions are used as the design indexes of mixed sensitivity. In order to select the weighted functions of the three sensitivity indexes, a method of determining the weighted functions based on dynamic tracking performance is proposed. The method is applied to the performance test of the servo control system of steering gear. The test results show that the hybrid sensitivity is used as the design index of the servo system PID control, and the control system has strong anti-interference ability and good tracking performance.