http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Saisai Duan,Wei Wang,Chenglei Yu,Mengjie Liu,Longyu Yu 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2019 NANO Vol.14 No.5
A practical sensor based on a glassy carbon electrode (GCE) modified with exfoliated graphene (GR) and poly (3,4-ethylenedioxythiophene): poly (styrene sulfonate) (PEDOT:PSS) was prepared to determine L-tryptophan (L-Trp) via differential pulse voltammetry (DPV). Optical microscopy was utilized to characterize the surface morphology of the composite electrode. Electrochemical behaviors of the composite electrodes were carried out via cyclic voltammetry (CV). According to DPV results, there are linear relationships between the peak currents and the concentrations in the ranges of 0.1–100 μmol L -1 and 100–1000 μmol L -1 for L-Trp, with the detection limit of 0.015 μmol L -1 for L-Trp. Moreover, the modified electrode can eliminate the interference effects of Ca2+, Mg2+, K+, Na+, L-tyrosine and ascorbic acid, which exhibit excellent stability and reproducibility.
Mechanical Properties of Steel Strands Cooled by Different Methods After High-Temperature Treatment
Long Liu,Lifeng Wang,Saisai Yu,Min Li 한국강구조학회 2022 International Journal of Steel Structures Vol.22 No.1
To study the mechanical properties of steel strands cooled by water at diff erent temperatures after high-temperature treatment, a two-stage experiment was conducted. First, tensile tests of 1860-grade steel wire specimens were conducted after heating to diff erent peak temperatures using 15 °C water and air for cooling. After that, tensile tests of steel strand specimens with the same heating temperature and diff erent cooling temperatures of water were conducted. The results showed that the ultimate strength of the steel wire fi rst decreased and then increased with increasing heating temperature under the air cooling method but decreased continuously under the water cooling method, which is in agreement with previous research results. The ultimate strength of the steel strands increased as a polynomial function of increasing cooling water temperature until the heating temperature reached 1000 °C. When the temperature of the cooling water increased from 10 to 80 °C, the stress increased from 19.61 to 139.88 MPa, while the stress increased sharply from 39.56 to 106.57 MPa as the temperature increased from 50 to 60 °C. The stress–strain relationship of steel strands cooled by water at diff erent temperatures was also studied. This study may provide a basis for the damage assessment of steel strands after fi re-related accidents.
Experimental study on the dynamic behavior of pervious concrete for permeable pavement
Jingwu Bu,Xudong Chen,Saisai Liu,Shengtao Li,Nan Shen 사단법인 한국계산역학회 2018 Computers and Concrete, An International Journal Vol.22 No.3
As the concept of “sponge city” is proposed, the pervious concrete for permeable pavement has been widely used in pavement construction. This paper aims at investigating the dynamic behavior and energy evolution of pervious concrete under impact loading. The dynamic compression and split tests are performed on pervious concrete by using split Hopkinson pressure bar equipment. The failure criterion on the basis of incubation time concept is used to analyze the dynamic failure. It is demonstrated that the pervious concrete is of a strain rate sensitive material. Under high strain rate loading, the dynamic strength increases while the time to failure approximately decreases linearly as the strain rate increases. The predicted dynamic compressive and split tensile strengths based on the failure criterion are in accordance with the experimental results. The total damage energy is found to increase with the increasing of strain rate, which means that more energy is needed to produce irreversible damage as loading rate increases. The fractal dimensions are observed increases with the increasing of impact loading rate.
Xudong Chen,Dandan Shi,Nan Shen,Shengtao Li,Saisai Liu 한국콘크리트학회 2019 International Journal of Concrete Structures and M Vol.13 No.1
As a solid pollutant, the recycled aggregate can be reused to replace the natural aggregate to cast pervious concrete, promoting resource recycling and reducing environmental pollution. Pervious concrete is usually applied to transportation engineering as pavements and decks, which are often subjected to fatigue loads in service. Therefore, it is essential to investigate the fatigue mechanical properties of pervious concrete. In this study, four-point cyclic bending loading test of natural aggregate pervious concrete and recycled aggregate pervious concrete were conducted under four different stress levels. By analyzing the experimental results, the mechanical performances, including hysteresis curve characteristics, damping ratio, dynamic elastic modulus and cyclic strain, of two kinds of pervious concrete under cyclic loading were revealed. Based on the improved EPF model, the relationship between fracture parameters, plastic strain and unloading strain were obtained. Besides, the relationship between the loading cycles and the ratio of plastic strain to unloading strain was received according to fatigue testing data under different stress levels. Further, the simplified fatigue model of pervious concrete was proposed and the experimental data was fitted with the model results. The fitting result reached a good agreement.
Jingwu Bu,Xudong Chen,Liangpeng Hu,Hanqing Yang,Saisai Liu 한국콘크리트학회 2020 International Journal of Concrete Structures and M Vol.14 No.3
The quantificational exploration of the propagation law of fracture process zone (FPZ) is of great importance to the research on concrete fracture. This paper performed fracture experiments on pre-cracked concrete beams under various loading rates. Digital image correlation (DIC) method was applied to obtain the whole field displacement of concrete in the fracture test. The crack opening displacement (COD) and the evolution of FPZ were determined based on the whole field displacement. The results show that the length of FPZ first increases and then decreases with the development of the effective crack length and the maximum length of FPZ is about 60 mm. It can be found that the length of FPZ corresponding to the peak load decreases with the increase of loading rates. Based on the fictitious crack model, a bilinear softening model was established. According to the proposed model, the mechanical behavior and the propagation law of FPZ were analyzed. The bilinear softening model can reflect the microcrack development and the aggregate interlocking in the FPZ.