http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Exact integration for the hypersingular boundary integral equation of two-dimensional elastostatics
Zhang, Xiaosong,Zhang, Xiaoxian Techno-Press 2008 Structural Engineering and Mechanics, An Int'l Jou Vol.30 No.3
This paper presents an exact integration for the hypersingular boundary integral equation of two-dimensional elastostatics. The boundary is discretized by straight segments and the physical variables are approximated by discontinuous quadratic elements. The integral for the hypersingular boundary integral equation analysis is given in a closed form. It is proven that using the exact integration for discontinuous boundary element, the singular integral in the Cauchy Principal Value and the hypersingular integral in the Hadamard Finite Part can be obtained straightforward without special treatment. Two numerical examples are implemented to verify the correctness of the derived exact integration.
Preparation and evaluation of porous H1.6Mn1.6O4@chitosan pellet for Li+ extraction
Xiaoxian Zhang,Yue Niu,Feng Xue,Jianhong Gao,Xiaolei Zhu,Shengui Ju 한국화학공학회 2021 Korean Journal of Chemical Engineering Vol.38 No.10
Spinel-structured lithium manganese oxide is regarded as one of the most promising materials that can recover Li+ from brine and seawater. Herein, a hierarchical porous and hydrophilic H1.6Mn1.6O4@chitosan pellet (HMO@CP) is proposed and its mechanical property is tailored through the glutaraldehyde-derived cross-linking. Different characterization techniques such as scanning electron microscopy (SEM), Brunner-Emmet-Teller (BET) measurement, Fourier transformation infrared spectrum (FTIR), and X-ray diffraction (XRD) meter were used to investigate the chemical and morphological properties of the HMO@CP. H1.6Mn1.6O4 powders were successfully encapsulated by chitosan, forming composite porous pellets. The equilibrium adsorption capacity of HMO@CP is 49.2mg·g1, which is similar to that of the pristine H1.6Mn1.6O4. Moreover, the adsorption behavior of HMO@CP well fits with the pseudosecond- order kinetic model, and the Langmuir model can be used to describe the adsorption isotherm of HMO@CP. Furthermore, the adsorption thermodynamic parameters such as H, G and S were calculated based on the obtained results. When the pellet is immersed into 0.05mol·L1 HCl solution after the Li+ adsorption process, the desorption equilibrium can be reached within 60 min, with a manganese dissolution loss of 2.48%. The Li+ adsorption capacity of HMO@CP remains at 41.92mg·g1 after five adsorption-desorption cycles, confirming the effective regeneration property of the HMO@CP. In addition, the as-prepared HMO@CP shows excellent selectivity for Li+ among Na+, K+, Mg2+, and Ca2+ ions in the simulated solution.
Exact integration for the hypersingular boundary integral equation of two-dimensional elastostatics
Xiaosong Zhang,Xiaoxian Zhang 국제구조공학회 2008 Structural Engineering and Mechanics, An Int'l Jou Vol.30 No.3
This paper presents an exact integration for the hypersingular boundary integral equation of two-dimensional elastostatics. The boundary is discretized by straight segments and the physical variables are approximated by discontinuous quadratic elements. The integral for the hypersingular boundary integral equation analysis is given in a closed form. It is proven that using the exact integration for discontinuous boundary element, the singular integral in the Cauchy Principal Value and the hypersingular integral in the Hadamard Finite Part can be obtained straightforward without special treatment. Two numerical examples are implemented to verify the correctness of the derived exact integration.
Hanbing Zhang,Jun Peng,Xiaoxian Lin,Bin Li,Qingsong Xia 한국지질과학협의회 2018 Geosciences Journal Vol.22 No.2
The tight sandstone reservoir of the Donghetang Formation underwent complex diagenetic processes for which the controlling factors remain unknown. Here, we present a case study of the lower member of this formation and show that this part of the reservoir consists mostly of lithic quartz sandstone with poor physical characteristics. Using core observation, thin section identification, electronic microprobe, scanning electronic microscopy, X-ray diffraction, and inclusion fluorescence microscopy, we identified five major diagenetic processes: compaction, cementation, dissolution, metasomatism, and hydrocarbon charging. Compaction and cementation have negative effects on petrophysical properties (referred to porosity and permeability of sandstone in this paper), and dissolution improves these properties. Diagenesis is affected by the depositional environment, and clastic constituents control compaction and dissolution; burial history and the geotemperature field control diagenesis at the macroscopic scale, while hydrocarbon charging affects the degree of cementation and dissolution. As oil saturation increases, the percentage of calcareous cements decreases and the development of secondary dissolved pores improves.