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Performances of Concrete Columns with Modular UHPC Permanent Formworks Under Axial Load
Yibo Yang,Baixi Chen,Yong Chen,Huanyang Zhou,Fucai Liu,Xiangming Xie,Junsheng Chen,Wenying Guo,Hengchang Wang 한국콘크리트학회 2023 International Journal of Concrete Structures and M Vol.17 No.5
This research proposed the modular prefabricated permanent formwork system made of ultra-high-performance concrete (UHPC). Two kinds of modular formwork shapes were designed: the flat formwork and the ribbed. The experimental investigation on the axial compression performance of the composite columns that consist of the normal strength concrete (NSC) core and the modular UHPC permanent formwork was demonstrated. Compared with the flat formwork, the ribbed formwork exhibited better bonding with the NSC core. As observed from the test results, the composite column with the ribbed formwork presented a similar axial behavior as the NSC column with a slight improvement in ultimate loads. Therefore, the modular UHPC ribbed permanent formwork could be regarded as the additional cover to the conventional NSC column. In addition, the finite element analysis (FEA) model was also developed to simulate the composite columns numerically. The predicted capacities agreed with the experimental results, which validated the numerical models. The crack pattern estimated by the FEA model revealed that the interaction between the permanent formwork and the inner concrete introduced many tiny cracks to the concrete core. However, as protected by the UHPC permanent formwork, the overall durability of the composite columns can still be enhanced.
Simulation of an X-ray Fresnel Zone Plate with Nonideal Factors
Chen, Jie,Fan, Quanping,Wang, Junhua,Yuan, Dengpeng,Wei, Lai,Zhang, Qiangqiang,Liao, Junsheng,Xu, Min Optical Society of Korea 2020 Current Optics and Photonics Vol.4 No.1
Fresnel zone plates have been widely used in many applications, such as x-ray telescopes, microfluorescence, and microimaging. To obtain an x-ray Fresnel zone plate, many fabrication methods, such as electron-beam etching, ion-beam etching and chemical etching, have been developed. Fresnel zone plates fabricated by these methods will inevitably lead to some nonideal factors, which have an impact on the focusing characteristics of the zone plate. In this paper, the influences of these nonideal factors on the focusing characteristics of the zone plate are studied systematically, by numerical simulations based on scalar diffraction theory. The influence of the thickness of a Fresnel zone plate on the absolute focusing efficiency is calculated for a given incident x-ray's wavelength. The diffraction efficiency and size of the focal spot are calculated for different incline angles of the groove. The simulations of zone plates without struts, with regular struts, and with random struts are carried out, to study the effects of struts on the focusing characteristics of a zone plate. When a Fresnel zone plate is used to focus an ultrashort x-ray pulse, the effect of zone-plate structure on the final pulse duration is also discussed.
Simulation of an X-ray Fresnel Zone Plate with Nonideal Factors
Jie Chen,Quanping Fan,Junhua Wang,Dengpeng Yuan,Lai Wei,Qiangqiang Zhang,Junsheng Liao,Min Xu 한국광학회 2020 Current Optics and Photonics Vol.4 No.1
Fresnel zone plates have been widely used in many applications, such as x-ray telescopes, microfluorescence, and microimaging. To obtain an x-ray Fresnel zone plate, many fabrication methods, such as electron-beam etching, ion-beam etching and chemical etching, have been developed. Fresnel zone plates fabricated by these methods will inevitably lead to some nonideal factors, which have an impact on the focusing characteristics of the zone plate. In this paper, the influences of these nonideal factors on the focusing characteristics of the zone plate are studied systematically, by numerical simulations based on scalar diffraction theory. The influence of the thickness of a Fresnel zone plate on the absolute focusing efficiency is calculated for a given incident x-ray’s wavelength. The diffraction efficiency and size of the focal spot are calculated for different incline angles of the groove. The simulations of zone plates without struts, with regular struts, and with random struts are carried out, to study the effects of struts on the focusing characteristics of a zone plate. When a Fresnel zone plate is used to focus an ultrashort x-ray pulse, the effect of zone-plate structure on the final pulse duration is also discussed.
Structural State Detection Using Transmissibility and Non-negative Matrix Factorization
Tongqun Ren,Meiling Hui,Junsheng Liang,Dazhi Wang,Liang He,Yonghang Chen 보안공학연구지원센터 2015 International Journal of Signal Processing, Image Vol.8 No.11
Transmissibility function (TF) was used in structural state detection which examined the change of the response-only vibration characteristics. The technology of signal correlation was utilized to obtain the TF between two testing points. Multiple TFs under different states were calculated as basic TFs and formed a state matrix. Subsequently, non-negative matrix factorization (NMF) was performed for the state matrix. Then both the basic and testing TFs were projected to the feature subspace derived from NMF so as to obtain the state feature index vectors, respectively. Finally, the Euclidean distance between state feature index vectors was defined as the state indicator. The experimental results indicated that this method can achieve better detection accuracy than that using magnitude indicator. Actually, a result with 100 percent correct detection was achieved when proper rule of dimensionality reduction was selected. This method is essentially a multivariate statistical process monitoring (MSPM) method. It is feasible in vibration-based structural state detection in the situation where the excitation signals are unavailable or inaccessible.
Zequn Zhang,Qijuan Dong,Zhibin Chen,Junsheng Wu,Jiuyang Xia,Kang Huang,Pengcheng Zuo,Wei Xue,Bowei Zhang 대한금속·재료학회 2024 METALS AND MATERIALS International Vol.30 No.2
The influence of Co content on the microstructure and corrosion behavior of Al0.3CoxCrFeNi (x = 0.25, 0.5 and 1.0) highentropy alloys were investigated. The results indicated that the increased content of Co improve the corrosion resistanceof alloy, which can be attributed to the distinction of phase composition in alloys caused by different Co content. TheAl0.3CoxCrFeNi alloy shows a double-phase (FCC + BCC) structure for x = 0.25 and 0.5, and BCC phase consists of (Al,Ni)-rich B2 phase and (Cr, Fe, Co)-rich A2 phase. The increase of Co content induces the transformations of crystalstructuresfrom BCC to FCC, resulting in the decrease of BCC phase proportion. The Al0.3CoCrFeNi alloy exhibits thesingle FCC structure, and all elements tend to be homogeneously distributed. The difference in the potential of FCC andBCC phases indicates the BCC phase acts as anode resulting to localized corrosion, while B2 phase preferentially dissolvescompared to the A2 phase due to the lower potential. Therefore, the existence of selective corrosion is found in thealloys with double-phase, by contrast, the alloy with single FCC phase shows random pitting corrosion.
Development of Testing Device for Critical Current Measurements for HTS/LTS
Qiuliang Wang,Yinming Dai,Baozhi Zhao,Shousen Song,Zhiqiang Cao,Shunzhong Chen,Quan Zhang,Housheng Wang,Junsheng Cheng,Yuanzhong Lei,Bai Ye,Xian Li,Jianhua Liu,Shangwu Zhao,Hongjie Zhang,Xinning Hu,Ch IEEE 2009 IEEE transactions on applied superconductivity Vol.19 No.3
<P>For the goal of superconducting magnet applications in the advanced testing device for high temperature superconducting (HTS) wire and sample coils, a wide bore conduction-cooled superconducting magnet with available warm bore of phi 186 mm and center field of 5 T for the background magnetic field applications was designed and fabricated and tested. A sample cryostat with two GM cryocoolers is inserted in the background magnet. The system allows measurements to be performed in a repeatable and reliable fashion. The detailed design, fabrication and thermal analysis are presented in the paper.</P>