First principles studies on the elastic, thermodynamic properties and electronic structure of Ti15−xMoxSn compounds

Chunmei Chen,Wei He,Lijing Ding,Xiaohui Song,Jinhui Huang,Tao Wang,Guoren Huang 한국물리학회 2018 Current Applied Physics Vol.18 No.3

The structural, elastic, thermodynamic and electronic properties of the Ti15−xMoxSn compounds were systematically investigated by means of first-principles calculations based on the density functional theory (DFT). The calculated results demonstrate the Ti15−xMoxSn compounds still remain the stable β phase structure. The calculation of cohesive energy shows that the structural stability of the Ti15−xMoxSn compounds increases apparently with the increase of Mo content. According to Hooke's law, the single crystal elastic constants were obtained and show that all the calculated compounds keep mechanical stability. Then the bulk modulus B, shear modulus G, Young's modulus E and Poisson's ratio ν of polycrystalline aggregates were calculated at zero pressure. The calculated results show that among these Ti15−xMoxSn compounds, Ti4Mo11Sn exhibits the largest stiffness while Ti12Mo3Sn shows the greatest ductility. The compounds Ti12Mo3Sn and Ti11Mo4Sn with the two lowest elastic Young's modulus of 61.01 GPa and 65.59 GPa are expected to be promising metallic biomaterials for implant applications. Besides, the Debye temperature ΘD and the electronic density of states (DOS) are also investigated and discussed.

Graph Theory-based Approach for Partial Topology Identification of Stochastic Multi-group Models With Multiple Dispersal

Chunmei Zhang,Dan Xia,Huiling Chen,Guiling Chen 제어·로봇·시스템학회 2023 International Journal of Control, Automation, and Vol.21 No.9

This paper is mainly concerned with partial topology identification of stochastic multi-group models with multiple dispersals (SMGMMD) by adaptive pinning control. By using a graph-theoretic approach and adaptive synchronization techniques, some sufficient criteria for partial topology identification of SMGMMD with time delay are obtained. Meanwhile, the partial topological structures of SMGMMD without time delay and the whole topological structures of SMGMMD can also be identified successfully. Finally, coupled Lorenz systems with time delay are identified to demonstrate the feasibility and effectiveness of theoretical results.

Flexural bearing capacity and stiffness research on CFRP sheet strengthened existing reinforced concrete poles with corroded connectors

Chen, Zongping,Song, Chunmei,Li, Shengxin,Zhou, Ji Techno-Press 2022 Structural monitoring and maintenance Vol.9 No.1

In mountainous areas of China, concrete poles with connectors are widely employed in power transmission due to its convenience of manufacture and transportation. The bearing capacity of the poles must have degenerated over time, and most of the steel connectors have been corroded. Carbon fiber reinforced polymer (CFRP) offers a durable, light-weight alternative in strengthening those poles that have served for many years. In this paper, the bearing capacity and failure mechanism of CFRP sheet strengthened existing reinforced concrete poles with corrosion steel connectors were investigated. Four poles were selected to conduct flexural capacity test. Two poles were strengthened by single-layer longitudinal CFRP sheet, one pole was strengthened by double-layer longitudinal CFRP sheets and the last specimen was not strengthened. Results indicate that the failure is mainly bond failure between concrete and the external CFRP sheet, and the specimens fail in a brittle pattern. The cross-sectional strains of specimens approximately follow the plane section assumption in the early stage of loading, but the strain in the tensile zone no longer conforms to this assumption when the load approaches the failure load. Also, bearing capacity and stiffness of the strengthened specimens are much larger than those without CFRP sheet. The bearing capacity, initial stiffness and elastic-plastic stiffness of specimen strengthened by double-layer CFRP are larger than those strengthened by single-layer CFRP. Weighting the cost-effective effect, it is more economical and reasonable to strengthen with single-layer CFRP sheet. The results can provide a reference to the same type of poles for strengthening design.

Investigation on compression properties of seawater-sea sand concrete

Chen, Zongping,Mo, Linlin,Song, Chunmei,Zhang, Yaqi Techno-Press 2021 Advances in concrete construction Vol.12 No.2

This paper introduces the experimental results of the influence of sea sand replacement rate and mixing water on the basic mechanical properties of sea sand concrete. A total of thirty test blocks were designed for uniaxial compression test. In this test two parameters were considered: (a) sea sand replacement ratio (i.e., 0%, 25%, 50%,75%, 100%); (b) water for mixing (i.e., freshwater, seawater). The entire stress-strain curve of sea sand concrete under uniaxial compression was obtained. Based on the test results, the influence of sea sand replacement rate and mixing water on the peak stress, peak strain, and deformation performance of sea sand concrete were analyzed. Test results showed that the stress-strain curves of seawater sea sand concrete were steeper than that of ordinary concrete, which indicated that seawater sea sand concrete was slightly more brittle. On the whole, the sea sand replacement rate had no significant effect on the axial compressive properties of sea sand concrete. Under the same sea sand replacement rate, the deformation performance of freshwater sea sand concrete (FSC) was slightly greater than that of seawater sea sand concrete (SSC). Seawater had an enhanced effect on the early strength development of sea sand concrete.

The Superiority of 68 Ga-FAPI-04 over 18F-FDG in a Case of Gallbladder Cancer

Chunmei Guo,Dengsai Peng,Ya Liu,Liming Chen,Zhanwen Huang 대한핵의학회 2022 핵의학 분자영상 Vol.56 No.5

A 56-year-old man presented with vague upper abdominal pain for more than 4 months. His abdominal ultrasound and MRI showed thickening of the neck and base of the gallbladder and nodule formation at the base of the gallbladder. 18F-FDG PET/CT revealed intense FDG uptake in the base of the gallbladder and multiple lymph nodes. 68 Ga-FAPI-04 PET/CT not only showed intense FAPI uptake in the above mentioned FDG-avid lesions but also showed intense FAPI uptake in the neck lesion of the gallbladder and some other additional lymph nodes. Finally, histopathological examination confirmed poorly differentiated tubular adenocarcinoma of the neck and base of the gallbladder. Our case illustrated that 68 Ga-FAPI-04 PET/CT may outperform 18F-FDG PET/CT in the detection of gallbladder cancer primary and metastatic lesions.

Electronic Transport and Magnetic Properties in Y<SUB>0.125</SUB>Ca<SUB>0.875</SUB>MnO₃ Perovskites

Zhenping Chen,Yuefeng Li,Yuling Su,Dewei Liu,Chunmei Wang,Jincang Zhang 한국자기학회 2008 한국자기학회 학술연구발표회 논문개요집 Vol.- No.-

Shedding Light on Soil Organic Matter-mineral Associations: Their Role in Carbon Cycling and Sequestration in the Terrestrial Environment

Donald Sparks,Chunmei Chen 한국토양비료학회 2014 한국토양비료학회 학술발표회 초록집 Vol.2014 No.6

Microwave-assisted pyrolysis of phosphoric acid-activated Goldenberry peel powder biochar for enhancing the adsorption of trace beta-lactamase inhibitors

Tian Ai,Chunmei Xu,Lei Zhang,Ke Chen,Yonggui Wu,Shujuan Dai,Xiaolu Xiong,Shixin Jie,Xiaoni Jin,Zhongxu Yu 한국화학공학회 2022 Korean Journal of Chemical Engineering Vol.39 No.9

Novel efficient biochar of Goldenberry peels (GBPMW-H3PO4) was prepared through a microwave-assistedphosphoric acid activation method. It was characterized and used for removing two beta-lactamase inhibitors, sulbactam(SAM, first listed in Japan in 1986) and avibactam (AVI, first listed in the U.S. in 2015), from aqueous solution. Characterization confirmed that GBPMW-H3PO4 displayed a high surface area (720.046m2 g1), more abundant porestructure, smaller particle size, and higher thermal stability. The experimental results showed that the adsorption of thetwo antibiotics was a spontaneous, favorable, and endothermic process, highly dependent on solution pH. A contacttime of 60 min assured equilibrium, and GBPMW-H3PO4 followed pseudo-first-order kinetics (R2=0.9950-0.9977). Furthermore,the adsorption capacities of GBPMW-H3PO4 for SAM and AVI were 211.86 and 198.81mg g1, respectively,and the performance was better than that of unmodified biochar. Microscopically, the main mechanism could beexplained by - electron donor-acceptor interaction, hydrogen bonding interaction, -hydrogen bonding, hydrophobicinteraction, and electrostatic interaction. The study demonstrates that the microwave-assisted H3PO4 activationmethod could produce biochar, and GBPMW-H3PO4 was confirmed to be a low-cost and high-efficiency adsorbent forremoving beta-lactamase inhibitors from medical wastewater.

Performance of Mg-Ti modified iron-based catalyst in NH3-SCR of NO at the presence of arsenic: Influence of oxygen and temperature

Xiaoyu Li,Juan Chen,Shouyan Chen,Chunmei Lu,Guangqian Luo,Hong Yao 한국공업화학회 2021 Journal of Industrial and Engineering Chemistry Vol.101 No.-

Impact of arsenic on the performance of Mg-Ti modified iron-based catalyst during selective catalyticreduction of NOx with ammonia was studied. The results indicated that Mg and Ti modification not onlyimproved the catalytic activity at 100–350 C, but also exhibited remarkable anti-arsenic ability. Mg wasdominant in the excellent anti-arsenic performance, and this role was firstly recognized. The anti-arsenicmechanism of Mg-Ti modified iron-based catalyst was ascribed to two aspects. One side, Mg exhibitedwell reactivity with arsenic which competed with Fe for the adsorption of arsenic and protected activeiron sites from arsenic occupation. The other side, presence of Mg promoted the formation of MgFe2O4in view of the strong interactions between Mg and Fe, suppressing the interactions between arsenicand Fe. Instead, gaseous arsenic turned to bond with Mg-O sites. Consequently, surface acid sites andfunction Fe-OH/ Fe = O bonds were preserved for de-NOx. Moreover, increase of oxygen content and temperatureweakened the deactivation of Mg-Ti modified iron-based catalyst by arsenic. It was due to theoxidation of As2O3 with oxygen content increase and the strengthened reactivity of non-active iron siteswith arsenic and Mg with arsenic as temperature elevation, inhibiting the interactions between activeiron sites with arsenic.

Fast Ambiguity Resolution using Galileo Multiple Frequency Carrier Phase Measurement

Shengyue Ji,Wu Chen,Chunmei Zhao,Xiaoli Ding,Yongqi Chen 한국항해항만학회 2006 한국항해항만학회 학술대회논문집 Vol.1 No.-

Rapid and high-precision positioning with a Global Navigation Satellite System (GNSS) is feasible only when very precise carrier-phase observations can be used. There are two kinds of mathematical models for ambiguity resolution. The first one is based on both pseudorange and carrier phase measurements, and the observation equations are of full rank. The second one is only based on carrier phase measurement, which is a rank-defect model. Though the former is more commonly used, the latter has its own advantage, that is, ambiguity resolution will be freed from the effects of pseudorange multipath. Galileo will be operational. One of the important differences between Galileo and current GPS is that Galileo will provide signals in four frequency bands. With more carrier-phase data available, frequency combinations with long equivalent wavelength can be formed, so Galileo will provide more opportunities for fast and reliable ambiguity resolution than current GPS. This paper tries to investigate phase only fast ambiguity resolution performance with four Galileo frequencies for short baseline. Cascading Ambiguity Resolution (CAR) method with selected optimal frequency combinations and LAMBDA method are used and compared. To validate the resolution, two tests are used and compared. The first one is a ratio test. The second one is lower bound success-rate test. The simulation test results show that, with LAMBDA method, whether with ratio test or lower bound success rate validation criteria, ambiguity can be fixed in several seconds, 8 seconds at most even when 1 sigma of carrier phase noise is 12 mm. While with CAR method, at least about half minute is required even when 1 sigma of carrier phase noise is 3 mm. It shows that LAMBDA method performs obviously better than CAR method.