Geometric accuracy of incremental sheet forming for TRIP590

Lihua Li,Jin Wang,Baoping Wang 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.11

TRIP steels have both high strength and good ductility, and they are typically used in automotive industry for the purpose of safety and energy saving. Deforming TRIP steel by ISF is practically valuable, but the application is significantly restricted by its geometric accuracy. At present, there is not enough research on geometric accuracy for TRIP steels. In this study, we explored the geometric accuracy of ISF for TRIP590 by referring to 1060Al steel and 08F steel. We found that the accuracy of TRIP590 steel was the lowest, which was because of the phase transformation of the material which occurred during deformation. To verify this, X-ray diffraction was employed to figure out the volume fraction of retained austenite. The results have shown that there is always TRIP effect during ISF process, and the relationship between natural logarithm of austenite volume fraction and the equivalent strain is negative linear. Lastly, it is proved that multiple reverse compensations could improve the geometric accuracy for TRIP steels.

The Feasibility Analysis of Recycled Aggregates from Construction and Demolition Waste for Permeable Pavement

Lihua Li,Xuanyu Shen,Jiabei Liu,Wentao Li,Chuheng Zhong,Xinlong Zhou 대한토목학회 2023 KSCE JOURNAL OF CIVIL ENGINEERING Vol.27 No.2

For reusing the construction and demolition waste (C&DW) materials and solving waterloggingproblems, the feasibility of applying C&DW to the permeable pavement (PP) was investigated. The recycled brick aggregate (RBA) and recycled concrete aggregate (RCA) were used as PPbase materials under different mixing ratios and grades. Geotextiles were also used in thisstudy as filter contaminants. Modified compaction tests, rainfall model tests, and columnleaching tests were conducted on a total of 15 samples with three gradations and five RBA andRCA mix ratios. The specimens for the rainfall model test were compacted at around optimummoisture content, and the degree of compaction was 97%. Using the sub-layer compactionmethod, each group of samples is compacted in five layers in strict accordance with thespecifications. In general, C&DW has the potential to be used underground without pollutionto the groundwater. The heavy metal concentrations in C&DW are less than in the local soiland related to material resources. The water yield performance was the best when 100%concrete was used to build PP, and the total water storage was the most when 100% of brickswere chosen to make PP. Due to the excellent permeability, C&DW can be selected forpavement fillers. The geotextile reduces the permeability by about 13% but effectively filtersout more than 50% of the fine particles in the rainfall. The permeability performance ofconcrete aggregates may be better than that of bricks, and fine particles can reduce thepermeability.

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.

Research on the Merger and Acquisition of Listing Corporation - A case Study of M & A Enterprise Knowledge Assets

LiHua Cui,De Li,HyeJeong Kim 보안공학연구지원센터 2014 International Journal of u- and e- Service, Scienc Vol.7 No.5

M & A is an important means for enterprises to achieve the rapid growth and development, is one of the important strategy for continuous operation in the process of company. M & A of knowledge assets is a kind of business means of rapid access to core technology and knowledge. More and more enterprises want to strengthen their ability through the M & A of other knowledge assets of enterprises, to enhance the market competitiveness of enterprises. With the development of M & A of knowledge assets, the enterprise wants to use the unique knowledge assets to increase the listed company's market performance and improve the financial structure of listed company. This paper draw some conclusions through the study of Chinese listed company which have taken knowledge assets mergers and acquisitions, to help people find some problems in the process of knowledge assets in mergers and acquisitions of listed companies, in order to provide some reference for China's listed companies in the M & A of knowledge assets.

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.

A Novel Combination Forecasting Algorithm Based on Time Series

Lihua Yang,Baolin Li,Xuetao Li,Lvjiang Yin 보안공학연구지원센터 2015 International Journal of Database Theory and Appli Vol.8 No.2

To effectively predict cigarette sales and improve the competitiveness of tobacco business enterprises, the characteristics of actual cigarette sales were detailed analyzed. Due to the long-term growth trends, seasonal fluctuations and the nonlinearity of monthly sales, we established three single forecasting models, which are Exponential Smoothing (ES), Seasonal Decomposition (SD) and Radial Basis Function (RBF) neural network. After obtaining the predicted value of three single models, the combination forecasting model was proposed. The weights of the three single models were computed using Mean Absolute Error and the mean relative error respectively, the result shows that relative error is more effective. A dynamic weight combination forecasting method based on RBF is proposed and compared with fixed weight method. Finally, the prediction accuracy of different models was compared based on the criteria of MAPE and RMSE, and the effectiveness of the combination method was proved, the proposed model can take advantage of the strengths of the three single models, the results indicate that the combination forecasting model suitable for cigarette sales has higher prediction accuracy. In some cases, the prediction accuracy of the fixed weight combination model is better than the dynamic weight combination model. The results can provide a certain reference to cigarette sales forecasting.

Mechanical Behavior of Reinforced Embankment with Different Recycling Waste Fillers

Lihua Li,Hongzhi Sheng,Henglin Xiao,Xinlong Zhou,Yiming Liu 대한토목학회 2022 KSCE Journal of Civil Engineering Vol.26 No.8

The application of construction and demolition (C&D) waste and used tires in geotechnical engineering contributes to the demand of the sustainable development. This study mainly compared the mechanical behavior of pure sand embankment (PSE), C&D material embankment (CDME), sand-tire shreds mixture embankment (STSME) through a scale model test. Effects of tire shreds content, the first layer geocell reinforcement burial depth, geocell reinforcement depth and compaction degree on the bearing capacity of embankments were investigated. Moreover, embankment load-settlement ratio, the reinforced bearing capacity ratio, the bearing capacity improvement factor (IF), the embankment surface deformation, and the vertical earth pressure distribution inside the embankment were discussed. Results indicate that both C&D material fillers and sand-tire shreds mixture can improve the bearing capacity and stability of embankment slopes. However, C&D material is better than sand-tire shreds mixture in the improvement. The optimum value of tire shreds content is 5%. The reinforcement effect of geocell decreases with the increase of reinforcement depth. With the increase of the buried depth of the first layer, it first increases and then decreases. With the increase of compaction degree increases. The minimum earth pressure appears near the slope. The bearing capacity of CDME is greater than STSME. The ultimate bearing capacity of CDME under the action of the geocell is twice that of the unreinforced embankment.

Effect of Ultrasonic Treatment on Grain Structure, Eutectic Phase and Mechanical Properties of an Al–6.2 wt% Cu Alloy

Li Zhang,Xiaoqian Li,Ripeng Jiang,Ruiqing Li,Lihua Zhang 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.5

The microstructural modification of eutectic phase is a crucial factor for the mechanical properties strengthening of the Al–Cu binary alloy. In this paper, Al–6.2% Cu melts were subjected to ultrasonic treatment from 710 or 660 °C with differentdurations. The microstructural evolutions of primary α-Al grains and α-Al + θ-Al2Cu eutectic phase under ultrasonicationwere investigated based on the nucleation and growth behavior. Results indicated that with the increase of ultrasonic processingtime, the growth of dendritic or petaloid grains were completely suppressed and noticeable refinement to globularmorphology were observed for α-Al grains. Meanwhile, broad lamella-like eutectic structure transformed to debris or evenparticles with continuous ultrasonication. Accordingly, the area fraction, average length and width of coarsening eutecticlamellas were dramatically reduced. In addition, the decrease of coarsening eutectic phase rather than the refinement ofα-Al grains was found to be the main contributor to the enhancement of mechanical properties for Al–6.2% Cu alloy. Themechanisms underlying the transformation of eutectic phase under ultrasonic treatment was also interpreted based on theexperimental results.

A biodegradable drug‐controlled delivery system based on mesoporous manganese dioxide and poly(dopamine)

Li Miaomiao,Cai Wenrong,Jiang Lihua,Li Junyao,Li Shan,Tang Tongtong,Kong Yong 대한화학회 2023 Bulletin of the Korean Chemical Society Vol.44 No.12

Mesoporous manganese dioxide (mMnO 2 ) was first synthesized for the loading of methotrexate (MTX), and then dopamine was in situ polymerized on the surface of the MTX‐loaded mMnO 2 (mMnO 2 ‐MTX) in an alkaline solution to encapsulate the drug in the mesopores of mMnO 2 . Both low pH and glutathione (GSH) can result in the degradation of mMnO 2 and poly(dopamine) (PDA), and thus the delivery of MTX from the mMnO 2 ‐MTX‐PDA can be triggered by low pH and GSH. Near‐infrared (NIR) light‐responsive delivery of MTX can be achieved owing to the outstanding photothermal conversion capability of PDA; on the other hand, the mMnO 2 ‐MTX‐PDA can be utilized for photothermal therapy under the irradiation of NIR light due to the elevated temperature. The results of cytotoxicity test demonstrate that the pH, GSH, and NIR light tri‐responsive drug‐controlled delivery system has excellent biocompatibility, while exhibits pronounced growth inhibition against murine breast tumor cell line 4T1. Mesoporous manganese dioxide (mMnO2) was first synthesized for the loading of methotrexate (MTX), and then dopamine was in situ polymerized on the surface of the MTX-loaded mMnO2 (mMnO2-MTX) in an alkaline solution to encapsulate the drug in the mesopores of mMnO2. Both low pH and glutathione (GSH) can result in the degradation of mMnO2 and poly(dopamine) (PDA), and thus the delivery of MTX from the mMnO2-MTX-PDA can be triggered by low pH and GSH. Near-infrared (NIR) light-responsive delivery of MTX can be achieved owing to the outstanding photothermal conversion capability of PDA; on the other hand, the mMnO2-MTX-PDA can be utilized for photothermal therapy under the irradiation of NIR light due to the elevated temperature. The results of cytotoxicity test demonstrate that the pH, GSH, and NIR light triresponsive drug-controlled delivery system has excellent biocompatibility, while exhibits pronounced growth inhibition against murine breast tumor cell line 4T1.

Pharmacokinetics, tissue distribution and excretion of peimisine in rats assessed by liquid chromatography-tandem mass spectrometry

Lihua Chen,Dongxun Li,Guosong Zhang,Wei Zhang,Lihua Zhang,Yongmei Guan,Weifeng Zhu,Hongning Liu 대한약학회 2015 Archives of Pharmacal Research Vol.38 No.6

Peimisine, the common ingredient of ‘‘zhebeimu’’groups and ‘‘chuanbeimu’’ groups, is responsiblefor the expectorant and cough relieving effects. The aim ofthis study was to investigate the pharmacokinetics, tissuedistribution and excretion of peimisine in male and femaleSD (Sprague-Dawley) rats by a rapid and sensitive LC-MS/MS (liquid chromatography-tandem mass spectrometry)method used carbamazepine as the internal standard afteroral administration, carbamazepine was stated as an IS. The results showed that peimisine was slowly distributed,and eliminated from rat plasma and manifested lineardynamics in a dose range of 0.26–6.5 mg/kg. Tested byANOVA, there were gender differences in the pharmacokineticparameters of AUC0-t, AUC0-? among a singledose of 0.26, 1.3, 6.5 mg/kg (P\0.05). Drug blood andtissue levels in male rats were significantly higher than thefemale counterparts after oral administration, while boththe males and the females showed high drug levels inspleen, kidney, lung, liver and heart. On the other hand, thepeimisine levels that can be reached in uterus, ovary, testisand brain is low. The excretion study showed that littleadministered peimisine (\0.7 %) was recovered in themale and female bile. Approximately 13.46 and 15.05 %were recovered in female urine and feces, while 43.07 and7.49 % were recovered in male urine and feces, respectively,which indicated that the major elimination route ofmale rats was urine excretion. In addition, there was significantdifferences in total cumulative excretive ratio ofpeimisine in feces (P\0.05) and no significant differencesin the urine (P[0.05) at a dose of 1.3 mg/kg.