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Weiping Zhang,Hui Liu,Yong Zhou,Kaixing Liao,Ying Huang Korean Nuclear Society 2023 Nuclear Engineering and Technology Vol.55 No.6
The aggregate-forming minerals in concrete undergo volume swelling and microstructure change under neutron irradiation, leading to degradation of physical and mechanical properties of the aggregates and concrete. A comprehensive investigation of volume change and elastic property variation of major aggregate-forming minerals is still lacking, so molecular dynamics simulations have been employed in this paper to improve the understanding of the degradation mechanisms. The results demonstrated that the densities of the selected aggregate-forming minerals of similar atomic structure and chemical composition vary in a similar trend with deposited energy due to the similar amorphization mechanism. The elastic tensors of all silicate minerals are almost isotropic after saturated irradiation, while those of irradiated carbonate minerals remain anisotropic. Moreover, the elastic modulus ratio versus density ratio of irradiated minerals is roughly following the density-modulus scaling relationship. These findings could further provide basis for predicting the volume and elastic properties of irradiated concrete aggregates in nuclear facilities.
Photo-Bleaching Eect in Divalent Samarium-Doped Alkaline-Earth Fluorohalides
Weiping Qin,Kiwan Jang,Changdae Kim,Hynngab Cho,Seongtae Park,Yonghwa Chung,Yong-ill Lee 한국물리학회 2004 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.45 No.2
When a CW laser was focused on a sample of divalent samarium-doped alkaline-earth uorohalides (Mg0:5Sr0:5FCl0:5Br0:5 : Sm2+ or BaFCl0:5Br0:5 : Sm2+), the uorescence intensity of Sm2+ ions decreased rapidly. Under irradiation from a 488-nm laser with a power density of 10 W/cm2, the intensity of the 5D0 ! 7F0 (Sm2+) emission decreased as much as 96 % of its initial intensity in 30 minutes (for an X-ray-reduced sample). The so-called photo-bleaching eect can be in uenced by the processes used for sample synthesis, such as the reduction method, the grinding process or X-ray irradiation. The decreasing curves obtained in the photo-bleaching experiments were tted, a biexponential decreasing mode was found, which included a fast decrease (time constant tens of seconds) and a slow decrease (time constant hundreds of seconds). There was no evidence to support the divalent samarium ions being photo-ionized into trivalent samarium ions in the photobleaching process. The most probable mechanism for the photo-bleaching eect involves structural defects and color centers in the samples.
A Novel Algorithm for Efficiently Sequential Pattern Mining
Weiping Wang,Lei Liu 인하대학교 정석물류통상연구원 2009 인하대학교 정석물류통상연구원 학술대회 Vol.2009 No.10
this paper proposed an IESE-Span algorithm using frequent itemsets to mine sequential patterns. This algorithm redefines the length of sequence and increases the granularity of mining sequential patterns. At first, this algorithm mines all the frequent itemsets as the increasing unit in the process of sequential pattern mining. Position information of frequent 2-itemsets (or sequences) is represented by frequent 2-itemsets (or sequences)-adjacency matrix and support degree of sequence is calculated by positions sets. Experiments show that the proposed algorithm is better in both time and space performance compared to traditional sequential pattern mining algorithm.
Study on moisture transport in concrete in atmospheric environment
Weiping Zhang,Fei Tong,Xianglin Gu,Yunping Xi 사단법인 한국계산역학회 2015 Computers and Concrete, An International Journal Vol.16 No.5
Moisture transport in concrete in atmospheric environment was studied in this paper. Based on the simplified formula of the thickness of the adsorbed layer, the pore-size distribution function of cement paste was calculated utilizing the water adsorption isotherms. Taking into consideration of the hysteresis effect in cement paste, the moisture diffusivity of cement paste was obtained by the integration of the pore-size distribution. Concrete is regarded as a two-phase composite with cement paste and aggregate, neglecting the moisture diffusivity of aggregate, then moisture diffusivity of concrete was evaluated using the composite theory. Finally, numerical simulation of humidity response during both wetting and drying process was carried out by the finite difference method of partial differential equation for moisture transport, and the numerical results well capture the trend of the measured data.
Weiping Sun,Okhwan Lee,Yeonchul Shin,Seongwon Kim,Changmok Yang,Hyoil Kim,Sunghyun Choi IEEE 2014 IEEE communications magazine Vol.52 No.11
<P>Wi-Fi has become an essential wireless technology in our daily lives, although the original intention of its introduction was to replace Ethernet cable. In this article, we outline the most remarkable features introduced during its ongoing technological evolution in terms of three major directions: throughput enhancement, longrange extension, and greater ease of use. By stitching these advanced features together, we also envision a promising future that Wi-Fi technology will bring us in terms of spectrum heterogeneity, seamless service provisioning, and possible relations with cellular networks.</P>
Design and aerodynamic characteristic analysis of unfolding-bending bionic flapping-wing aircraft
Weiping Shao,Hui Zhang,Pengfei Zeng 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.6
A bionic flapping-wing aircraft model is designed in this study to achieve unfolding-bending effect of a bird’s wings during flight, realize active unfolding-bending movement, and demonstrate rapid return characteristic of flapping-bending motion. We use the new method of ADAMS and XFlow cosimulation to analyze its aerodynamic characteristics and investigate effects of flutter frequency, air flow velocity, fuselage angle of attack, and aileron torsion angle on its aerodynamic characteristics. Results showed that increasing the flapping frequency can significantly improve aerodynamic characteristics, increasing the air flow velocity will reduce aerodynamic characteristics, decreasing the fuselage angle of attack will reduce peak lift and increase peak thrust, and increasing the aileron torsion angle will reduce the rising resistance and increase forward thrust. The analysis results showed the excellent aerodynamic characteristics of the model.