The Dynamic Mechanical Properties for Recycled Aggregate Concrete under Tensile-Compressive States

Zhen-Jun He,Zhi-qiang Wang,Meng-jia Ding,Zhen-wei Wang,Xiao-jie Zhang,Lian-shuo Liu 대한토목학회 2020 KSCE Journal of Civil Engineering Vol.24 No.5

The experiments under biaxial tensile-compressive (T-C) complex stress were carried out for two kinds of substitution percentages of recycled coarse aggregate (RCA) on biaxial proportional loading (α = σ1:σ3 =1:0, 0: -1, 0.05: -1, 0.1: -1, 0.25: -1, 0.5: -1, 1: -1 and-1: -1) and four loading deformation rates of 10−5/s, 10−4/s , 10−3/s, and 10−2/s. The research was completed in the static-dynamic true triaxial machine. The experimental phenomena indicate the tensile failure appears in these specimens of recycled aggregate concrete (RAC) under biaxial T-C stress states. The dynamic mechanical behavior for RAC under biaxial T-C loadings was affected by the strain rates, stress ratios and its substitution percentages of RCA. Accompanied by the increase of strain rates, its strength of RAC is improved. As the tensile stress increases, its compressive strength decreases. The T-C strengths for RAC under biaxial T-C states are less than its corresponding uniaxial T-C strengths at a certain identical strain rates, respectively. Considering the effect of loading rates, a new tensile-compressive failure criterion is established under complex stress states.

Effect of Sub-Structure and Precipitation Behavior on Mechanical Properties of Al–xCu–Li Alloys

Yu‑zhuo Li,Guang‑jun Zeng,Ding‑ding Lu,Zhen‑zhen Liu,San‑xi Deng,Peng‑cheng Ma,Yong‑lai Chen,Rui‑feng Zhang,Jin‑feng Li 대한금속·재료학회 2023 METALS AND MATERIALS International Vol.29 No.11

The tensile properties and microstructure of extruded and cold rolled 2A55 Al–Li alloys with different Cu content werestudied. After solution treatment, the strength of extruded sheets is slightly higher than that of cold rolled sheets due to strongdeformation texture and high density of substructure. However, the strength change order is different with the increase of Cucontent with T6-24 h. The extruded sample with higher Cu content have higher strength due to many dense T1precipitates. The δ′/θ′/δ′ composite precipitates and θ′ precipitates suppress the formation of T1precipitates, which cause cold rolled samplewith higher Cu content shows lower strength. Additionally, many fine T1precipitates nucleate at the sub-grain boundariesformed in the extrusion process, which have a significant effect on the mechanical property.

Study of failure analysis and manufacturing processes improvement of cracking connecting rod

Zhen Zhang,Anyuan Jiao,Xiwei Lv,Haodong Ding 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.11

Herein, we provide a novel method of using finite element analysis to guide the improvement of manufacturing processes on the basis of physicochemical analysis. First, based on the theoretical analysis of the force of the connecting rod, the solid model of cracking connecting rod is established by SolidWorks. Then the static stress analysis, modal analysis and fatigue analysis are carried out by ANSYS, determining the location where the connecting rod is prone to failure. Second, the influence of processing technology and other factors on the failure of connecting rod is analyzed, and several improved schemes for the manufacturing process are proposed. Finally, the fatigue test of the connecting rod is performed to verify the effect. Compared with the unimproved connecting rod, the tension and pressure of the improved connecting rod increased to 92.34 KN and -425.7 KN, respectively. The safety factor under this load is 1.8, which has increased by 20 % compared to 1.5 before the improvement.

Phosphoric Acid Modified Nb2O5: A Selective and Reusable Catalyst for Dehydration of Sorbitol to Isosorbide

Zhen-Chen Tang,Ding-Hua Yu,Peng Sun,Heng Li,He Huang 대한화학회 2010 Bulletin of the Korean Chemical Society Vol.31 No.12

Niobium oxide (Nb2O5) and phosphated Nb2O5 were synthesized and used as catalysts for sorbitol dehydration to isosorbide. The characterization results of N2 adsorption, XRD and NH3-TPD revealed that the phosphoric acid modification could well prevent the crystallization of Nb2O5. And the amorphous phosphated Nb2O5 catalysts kept the relatively large surface area and stable acidity at high calcination temperature. The catalytic results showed that the selectivity to isosorbide could be dramatically enhanced over phosphated Nb2O5. The excellent catalytic performance with 100.0% sorbitol conversion and 62.5% isosorbide selectivity were obtained over the .8P/NBO-400 catalyst. Comparing with Nb2O5 catalysts, phosphated Nb2O5 catalysts regenerated through a simple calcination process showed no significant activity loss after recycling three runs.

Compatibility of Neural Stem Cells with Functionalized Selfassembling Peptide Scaffold In vitro

Zhen Xing Zhang,Ding Jun Hao,Qi Xin Zheng,Yong Chao Wu 한국생물공학회 2010 Biotechnology and Bioprocess Engineering Vol.15 No.4

In this study, we evaluated the behavior of neural stem cells (NSCs) using a new peptide hydrogel scaffold named IKVAVmx, which was made by mixing self-assembling peptide RADA16 and designer peptide RADA16-IKVAV solutions. NSCs derived from rat cerebral cortex were culture-expanded in neuorobasal medium and seeded on the RADA16 and IKVAVmx hydrogels. Cells could penetrate the hydrogels and form a 3D cellular network. Compared to pure RADA16 scaffold, we found that IKVAVmx scaffold significantly promoted cell proliferation and stimulated cell migration into the 3D scaffold. Moreover, Immunocytochemistry and Western blot analysis indicated that the differentiation ratio of neurons from NSCs in IKVAVmx scaffold was higher than that in pure RADA16 scaffold. These results suggested that this new hydrogel scaffold provided an ideal substrate for NSCs 3D culture and suggested its further application for neural tissue engineering.

Analysis of common and characteristic actions of Panax ginseng and Panax notoginseng in wound healing based on network pharmacology and meta-analysis

Zhen Wang,Xueheng Xie,Mengchen Wang,Meng Ding,Shengliang Gu,Xiaoyan Xing,Xiaobo Sun 고려인삼학회 2023 Journal of Ginseng Research Vol.47 No.4

Geolocation Spectrum Database Assisted Optimal Power Allocation: Device-to-Device Communications in TV White Space

( Zhen Xue ),( Liang Shen ),( Guoru Ding ),( Qihui Wu ) 한국인터넷정보학회 2015 KSII Transactions on Internet and Information Syst Vol.9 No.12

TV white space (TVWS) is showing promise to become the first widespread practical application of cognitive technology. In fact, regulators worldwide are beginning to allow access to the TV band for secondary users, on the provision that they access the geolocation database. Device-to-device (D2D) can improve the spectrum efficiency, but large-scale D2D communications that underlie TVWS may generate undesirable interference to TV receivers and cause severe mutual interference. In this paper, we use an established geolocation database to investigate the power allocation problem, in order to maximize the total sum throughput of D2D links in TVWS while guaranteeing the quality-of-service (QoS) requirement for both D2D links and TV receivers. Firstly, we formulate an optimization problem based on the system model, which is nonconvex and intractable. Secondly, we use an effective approach to convert the original problem into a series of convex problems and we solve these problems using interior point methods that have polynomial computational complexity. Additionally, we propose an iterative algorithm based on the barrier method to locate the optimal solution. Simulation results show that the proposed algorithm has strong performance with high approximation accuracy for both small and large dimensional problems, and it is superior to both the active set algorithm and genetic algorithm.

Reference gene selection for RT-qPCR analysis in two invasive whiteflies after the acquisition of vectored or non-vectored viruses

Zhen-Hong Lv,Hui-Peng Pan,Wei Zhang,Tian-Bo Ding,Dong Chu 한국응용곤충학회 2018 Journal of Asia-Pacific Entomology Vol.21 No.1

Custom reference gene selection is essential for reverse transcriptase-quantitative polymerase chain reaction(RT-qPCR) in different species of insects and various experiment conditions. In this study, 14 candidate referencegenes (HSP40, HSP20, HSP70, HSP90, v-ATPase, RPL29, EF-1, SDHA, Actin, PPIA, GAPDH, MyosinL,NADH, and γ-tubulin) were analyzed using five different programs including ΔCt method, BestKeeper, geNorm,NormFinder, and ReFinder to validate their use as reference genes in two invasive whiteflies, Bemisia tabaci Band Q, after acquiring the vectored virus, Tomato yellow leaf curl virus (TYLCV), or ingesting the non-vectoredvirus, Tomato spotted wilt virus (TSWV), respectively. The results showed that HSP40, v-ATPase, and EF-1 werethe most stable genes in B. tabaci B (B. tabaci B feeding on the healthy, TYLCV- and TSWV-infected tomatoplant), PPIA, SDHA, and RPL29 were the most stable genes in B. tabaci Q (B. tabaci Q feeding on the healthy,TYLCV- and TSWV-infected tomato plant). In addition, EF-1, RPL29, and HSP20 were the most stable referencegenes in B. tabaci B and Q. These findings provide the basis for future RT-qPCR-based studies on whitefly-virus interactions. Meanwhile,this report may set a precedent for reference gene selection in insects after the ingestion of non-vectored viruses.

An effective online delay estimation method based on a simplified physical system model for real-time hybrid simulation

Zhen Wang,Bin Wu,Guoshan Xu,Yong Ding,Oreste S. Bursi 국제구조공학회 2014 Smart Structures and Systems, An International Jou Vol.14 No.6

Real-Time Hybrid Simulation (RTHS) is a novel approach conceived to evaluate dynamic responses of structures with parts of a structure physically tested and the remainder parts numerically modelled. In RTHS, delay estimation is often a precondition of compensation; nonetheless, system delay may vary during testing. Consequently, it is sometimes necessary to measure delay online. Along these lines, this paper proposes an online delay estimation method using least-squares algorithm based on a simplified physical system model, i.e., a pure delay multiplied by a gain reflecting amplitude errors of physical system control. Advantages and disadvantages of different delay estimation methods based on this simplified model are firstly discussed. Subsequently, it introduces the least-squares algorithm in order to render the estimator based on Taylor series more practical yet effective. As a result, relevant parameter choice results to be quite easy. Finally in order to verify performance of the proposed method, numerical simulations and RTHS with a buckling-restrained brace specimen are carried out. Relevant results show that the proposed technique is endowed with good convergence speed and accuracy, even when measurement noises and amplitude errors of actuator control are present.

A long-term tunnel settlement prediction model based on BO-GPBE with SHM data

Yang Ding,Yu-Jun Wei,Pei-Sen Xi,Peng-Peng Ang,Zhen Han 국제구조공학회 2024 Smart Structures and Systems, An International Jou Vol.33 No.1

The new metro crossing the existing metro will cause the settlement or floating of the existing structures, which will have safety problems for the operation of the existing metro and the construction of the new metro. Therefore, it is necessary to monitor and predict the settlement of the existing metro caused by the construction of the new metro in real time. Considering the complexity and uncertainty of metro settlement, a Gaussian Prior Bayesian Emulator (GPBE) probability prediction model based on Bayesian optimization (BO) is proposed, that is, BO-GPBE. Firstly, the settlement monitoring data are analyzed to get the influence of the new metro on the settlement of the existing metro. Then, five different acquisition functions, that is, expected improvement (EI), expected improvement per second (EIPS), expected improvement per second plus (EIPSP), lower confidence bound (LCB), probability of improvement (PI) are selected to construct BO model, and then BO-GPBE model is established. Finally, three years settlement monitoring data were collected by structural health monitoring (SHM) system installed on Nanjing Metro Line 10 are employed to demonstrate the effectiveness of BO-GPBE for forecasting the settlement.