Raman scattering investigations on Co-doped ZnO epitaxial films: Local vibration modes and defect associated ferromagnetism

Qiang Cao,Shumin He,Yuanyuan Deng,Dapeng Zhu,Xiaodong Cui,Guolei Liu,Huai-Jin Zhang,Shishen Yan,Yanxue Chen,Liangmo Mei 한국물리학회 2014 Current Applied Physics Vol.14 No.5

Raman scattering spectroscopy has been performed on high quality Co-doped ZnO epitaxial films, which were grown on Al2O3 (0001) by oxygen-plasma assisted molecular beam epitaxy. Raman measurements revealed two local vibration modes (LVMs) at 723 and 699 cm1 due to the substitution of Co2þ in wurtzite ZnO lattice. The LVM at 723 cm1 is found to be an elemental sensitive vibration mode for Co substitution. The LVM at 699 cm1 can be attributed to enrichment of Co2þ bound with oxygen vacancy, the cobalteoxygen vacancyecobalt complexes, in Zn1xCoxO films associated with ferromagnetism. The intensity of LVM at 699 cm1, as well as saturated magnetization, enhanced after the vacuum annealing and depressed after oxygen annealing.

Research on Seismic Performance of Corrugated Steel Plate Shear Walls with Inelastic Buckling Subjected to Lateral Loads

Qiang Cao,Jing Yu Huang,Dong-Zhou Wang,Liang Zhao,Zhe Wei Wu 한국강구조학회 2022 International Journal of Steel Structures Vol.22 No.3

The corrugated steel plate shear wall (CSPSW) with inelastic buckling of a corrugated steel plate (CSP) could restrict the elastic out-of-plane buckling of in-fi lled steel plates with appropriate CSPs, and lateral displacement could be restricted in the structures. So, the CSPSWs with inelastic buckling of CSPs could be applicable in high buildings or the structures with strict requirements of lateral displacement. This paper presents the research works on the seismic behaviour of the CSPSW with inelastic buckling of a corrugated steel plate. A numerical model was developed to simulate the seismic performance of the CSPSW with the inelastic buckling of the CSP, and the FE model was validated through experiment. Subsequently, parametric analyses were performed to investigate for the eff ects of those key parameters on the seismic behaviour of CSPSWs, such as the height—thickness ratio, aspect ratio, horizontal panel width, corrugation angle, initial imperfections, and surrounding frame stiff ness. The buckling and post buckling behaviour, failure modes, ductility and energy absorption capacity of the shear walls were discussed. The results reveal that the CSPSW show high strength, better ductility, and stable hysteretic characteristics. The failure modes of the CSPSWs with CSPs inelastic buckling are the failure of the tension fi eld strips along the along the diagonals in the whole CSPs. And the corners of CSPs in CSPs are weak parts, which should be strengthened in future designs. Besides these, the surrounding frame stiff ness should be greater than I c min to ensure energydissipating capacity and buckling capacity stability of CSPSWs.

Association of MDR1 Gene Polymorphisms with Susceptibility to Hepatocellular Carcinoma in the Chinese Population

Ren, Yong-Qiang,Han, Ju-Qiang,Cao, Jian-Biao,Li, Shao-Xiang,Fan, Gong-Ren Asian Pacific Journal of Cancer Prevention 2012 Asian Pacific journal of cancer prevention Vol.13 No.11

Objective: The objective of this study was to evaluate the association of MDR1 gene polymorphisms with susceptibility to hepatocellular carcinoma (HCC). Methods: A total of 689 HCC patients and 680 cancer-free subjects were enrolled. Human MDR1 gene polymorphisms were investigated by created restriction site-polymerase chain reaction (CRS-PCR) and DNA sequencing methods. Multiple logistic regression models were applied to estimate the association between MDR1 gene polymorphisms and susceptibility to HCC. Results: We detected a novel c.4125A>C polymorphism and our findings suggested that this variant was significantly associated with susceptibility to HCC. A significantly increased susceptibility to HCC was noted in the homozygote comparison (CC versus AA: OR=1.621, 95% CI 1.143-2.300, ${\chi}^2$=7.4095, P=0.0065), recessive model (CC versus AC+AA: OR=1.625, 95% CI 1.167-2.264, ${\chi}^2$=8.3544, P=0.0039) and allele contrast (C versus A: OR=1.185, 95% CI 1.011-1.389, ${\chi}^2$=4.4046, P=0.0358). However, no significant increase was observed in the heterozygote comparison (AC versus AA: OR=0.995, 95% CI 0.794-1.248, ${\chi}^2$=0.0017, P=0.9672) and dominant model (CC+AC versus AA: OR=1.106, 95% CI 0.894-1.369, ${\chi}^2$=0.8560, P=0.3549). Conclusions: These findings suggest that the c.4125A>C polymorphism of the MDR1 gene might contribute to susceptibility to HCC in the Chinese population. Further work will be necessary to clarify the relationship between the c.4125A>C polymorphism and susceptibility to HCC on larger populations of diverse ethnicity.

Adjoint inversion of Chinese non-methane volatile organic compound emissions using space-based observations of formaldehyde and glyoxal

Cao, Hansen,Fu, Tzung-May,Zhang, Lin,Henze, Daven K.,Miller, Christopher Chan,Lerot, Christophe,Abad, Gonzalo Gonzá,lez,De Smedt, Isabelle,Zhang, Qiang,van Roozendael, Michel,Hendrick, Fran&cced Copernicus GmbH 2018 Atmospheric Chemistry and Physics Vol.18 No.20

<P><p><strong>Abstract.</strong> We used the GEOS-Chem model and its adjoint to quantify Chinese non-methane volatile organic compound (NMVOC) emissions for the year 2007, using the tropospheric column concentrations of formaldehyde and glyoxal observed by the Global Ozone Monitoring Experiment 2A (GOME-2A) instrument and the Ozone Monitoring Instrument (OMI) as quantitative constraints. We conducted a series of inversion experiments using different combinations of satellite observations to explore their impacts on the top-down emission estimates. Our top-down estimates for Chinese annual total NMVOC emissions were 30.7 to 49.5 (average 41.9) Tg<span class='thinspace'></span>yr<span class='inline-formula'>⁻¹</span>, including 16.4 to 23.6 (average 20.2) Tg<span class='thinspace'></span>yr<span class='inline-formula'>⁻¹</span> from anthropogenic sources, 12.2 to 22.8 (average 19.2) Tg<span class='thinspace'></span>yr<span class='inline-formula'>⁻¹</span> from biogenic sources, and 2.08 to 3.13 (average 2.48) Tg<span class='thinspace'></span>yr<span class='inline-formula'>⁻¹</span> from biomass burning. In comparison, the a priori estimate for Chinese annual total NMVOC emissions was 38.3<span class='thinspace'></span>Tg<span class='thinspace'></span>yr<span class='inline-formula'>⁻¹</span>, including 18.8<span class='thinspace'></span>Tg<span class='thinspace'></span>yr<span class='inline-formula'>⁻¹</span> from anthropogenic sources, 17.3<span class='thinspace'></span>Tg<span class='thinspace'></span>yr<span class='inline-formula'>⁻¹</span> from biogenic sources, and 2.27<span class='thinspace'></span>Tg<span class='thinspace'></span>yr<span class='inline-formula'>⁻¹</span> from biomass burning. The simultaneous use of glyoxal and formaldehyde observations helped distinguish the NMVOC species from different sources and was essential in constraining anthropogenic emissions. Our four inversion experiments consistently showed that the Chinese anthropogenic emissions of NMVOC precursors of glyoxal were larger than the a priori estimates. Our top-down estimates for Chinese annual emission of anthropogenic aromatics (benzene, toluene, and xylene) ranged from 5.5 to 7.9<span class='thinspace'></span>Tg<span class='thinspace'></span>yr<span class='inline-formula'>⁻¹</span>, 2<span class='thinspace'></span>% to 46<span class='thinspace'></span>% larger than the estimate of the a priori emission inventory (5.4<span class='thinspace'></span>Tg<span class='thinspace'></span>yr<span class='inline-formula'>⁻¹)</span>. Three out of our four inversion experiments indicated that the seasonal variation in Chinese NMVOC emissions was significantly stronger than indicated in the a priori inventory. Model simulations driven by the average of our top-down NMVOC emission estimates (which had a stronger seasonal variation than the a priori) showed that surface afternoon ozone concentrations over eastern China increased by 1-8<span class='thinspace'></span>ppb in June and decreased by 1-10<span class='thinspace'></span>ppb in December relative to the simulations using the a priori emissions and were in better agreement with measurements. We concluded that the satellite observations of formaldehyde and glyoxal together provided quantitative constraints on the emissions and source types of NMVOCs over China and improved our understanding on regional chemistry.</p> </P>

Numerical studies on non-shear and shear flows past a 5:1 rectangular cylinder

Qiang Zhou,Shuyang Cao,Zhiyong Zhou 한국풍공학회 2013 한국풍공학회지 Vol.17 No.4

Large Eddy Simulations (LES) were carried out to investigate the aerodynamic characteristics of a rectangular cylinder with side ratio B/D=5 at Reynolds number Re=22,000 (based on cylinder thickness). Particular attention was devoted to the effects of velocity shear in the oncoming flow. Time-averaged and unsteady flow patterns around the cylinder were studied to enhance understanding of the effects of velocity shear. The simulation results showed that the Strouhal number has no significant variation with oncoming velocity shear, while the peak fluctuation frequency of the drag coefficient becomes identical to that of the lift coefficient with increase in velocity shear. The intermittently-reattached flow that features the aerodynamics of the 5:1 rectangular cylinder in non-shear flow becomes more stably reattached on the high-velocity side, and more stably separated on the low-velocity side. Both the mean and fluctuating drag coefficients increase slightly with increase in velocity shear. The mean and fluctuating lift and moment coefficients increase almost linearly with velocity shear. Lift force acts from the high-velocity side to the low-velocity side, which is similar to that of a circular cylinder but opposite to that of a square cylinder under the same oncoming shear flow.

The study of the life cycle of small and medium-sized enterprises based on external environmental perspective—empirical research which takes 5 metropolises including Shenzhen as samples

CAO Yu,Wang Fu-Qiang,Ma Yue-ru 인하대학교 정석물류통상연구원 2009 인하대학교 정석물류통상연구원 학술대회 Vol.2009 No.10

Based on the research of small and medium-sized enterprises’ life cycle, plus the data and information that acquired from cancelled small and medium ?sized enterprises in five metropolises including Shenzhen, Guangzhou, Changesh, Zhengzhou and Chengdu during period 200-2007, the relationship between the life cycle of small and medium-sized enterprises in the five metropolises and their external environment is evaluated and comparatively analyzed. The results shows that the external environment has positive impact on SMEs’ lifecycle, and economic environment, technological environment as well as human resources environment have prominent influences on SEMs’ lifecycle, but the influences of political environment, socioculture environment and natural resources environment on SEMs’ lifecycle are inconspicuous Further more, the results above is analyzed and the countermeasures on how to prolong the llife cycle of small and medium-sized enterprise in our country from the perspectives of both government and corporation are proposed

Quantum Bee Colony Optimization and Non-dominated Sorting Quantum Bee Colony Optimization Based Multi-relay Selection Scheme

( Qiang Ji ),( Shifeng Zhang ),( Haoguang Zhao ),( Tiankui Zhang ),( Jinlong Cao ) 한국인터넷정보학회 2017 KSII Transactions on Internet and Information Syst Vol.11 No.9

In cooperative multi-relay networks, the relay nodes which are selected are very important to the system performance. How to choose the best cooperative relay nodes is an optimization problem. In this paper, multi-relay selection schemes which consider either single objective or multi-objective are proposed based on evolutionary algorithms. Firstly, the single objective optimization problems of multi-relay selection considering signal to noise ratio (SNR) or power efficiency maximization are solved based on the quantum bee colony optimization (QBCO). Then the multi-objective optimization problems of multi-relay selection considering SNR maximization and power consumption minimization (two contradictive objectives) or SNR maximization and power efficiency maximization (also two contradictive objectives) are solved based on non-dominated sorting quantum bee colony optimization (NSQBCO), which can obtain the Pareto front solutions considering two contradictive objectives simultaneously. Simulation results show that QBCO based multi-relay selection schemes have the ability to search global optimal solution compared with other multi-relay selection schemes in literature, while NSQBCO based multi-relay selection schemes can obtain the same Pareto front solutions as exhaustive search when the number of relays is not very large. When the number of relays is very large, exhaustive search cannot be used due to complexity but NSQBCO based multi-relay selection schemes can still be used to solve the problems. All simulation results demonstrate the effectiveness of the proposed schemes.

Influence of Layer Thickness Ratio on the Mechanical and Failure Properties of Soft-Hard Interbedded Rock-like Material

Qiang Xie,Hao Gao,Yuxin Ban,Xiang Fu,Xiaowen Liang,Zhilin Cao,Jun Duan 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.11

To figure out the influence of soft-hard layer thickness ratio on specimens’ mechanical properties evolution and microcracking mechanism, combined with digital image correlation technology and acoustic emission facility, uniaxial compression tests were conducted on soft-hard interbedded rock-like materials considering seven bedding dip angles and two soft-hard layer thickness ratios. The results are as follows: 1) The failure mode and failure pattern of layered rock masses are mainly determined by the bedding dip angle α and are less related to the soft-hard thickness ratio. With the increase of dip angle, the failure strength curve of the specimen is approximately U-shaped, and the soft-hard layer thickness ratio affects the U-shaped. The decrease in soft-hard layer thickness ratio will reduce the uniaxial compressive strength of specimens with low dip angles (α≦30°), cause differences in the evolution path of local strain fields of layered rock masses and reduce the horizontal displacement of the main crack. 2) The increase of the proportion of soft layer in the soft-hard layer thickness ratio will reduce the proportion of tensile cracks in the tensile failure specimens and shear cracks in the shear failure specimens, complicating the process of cracks of the layer rock mass. 3) Increasing the proportion of soft layers in the soft-hard layers thickness ratio promotes the generation of secondary cracks in layered rock masses and further reduces the integrity of specimens. Finally, through the findings in this paper, it can provide a reference for analyzing the crack propagation behavior of layered rock.

Weak fault feature extraction of rolling bearing under strong poisson noise and variable speed conditions

Qiang Ma,Shuqian Cao,Tao Gong,Jianhua Yang 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.11

Fault feature extraction of the rolling bearing under strong background noise is always a difficult problem in bearing fault diagnosis. At present, most of the research focuses on weak signal extraction under Gaussian white noise and has certain practical significance. However, the noise in engineering is often complex and changeable, Gaussian white noise cannot fully simulate the actual strong background noise. Poisson white noise is a type of typical non-Gaussian noise, which widely exists in complex mechanical impact. It is of great significance to study the weak fault feature extraction of a faulty bearing under this type of noise. At the same time, variable speed conditions occupy most rotating machinery speed conditions. Non-stationary vibration signals make it difficult to extract fault features, and the frequency spectrum ambiguity will occur because of speed fluctuation. To solve the above problems, a method of weak feature extraction of a faulty bearing based on computed order analysis (COA) and adaptive stochastic resonance (SR) is proposed. Firstly, by numerical simulation, the nonstationary fault characteristic signal corrupted with strong Poisson noise is transformed into a stationary signal in the angle domain by COA. Secondly, the influence of the parameters of the pulse arrival rate and noise intensity of Poisson white noise on the optimal SR response in the angle domain are studied, and the influence of the parameters of Poisson white noise on the fault feature extraction is given. Then, adaptive SR method is used to extract and enhance fault feature information. Finally, the effectiveness of this method in weak fault characteristic signal extraction under strong Poisson noise is verified by experiments. Numerical simulation and experimental results verify the effectiveness of the proposed method in bearing fault diagnosis under strong Poisson noise and variable speed conditions.

Numerical studies on non-shear and shear flows past a 5:1 rectangular cylinder

Zhou, Qiang,Cao, Shuyang,Zhou, Zhiyong Techno-Press 2013 Wind and Structures, An International Journal (WAS Vol.17 No.4

Large Eddy Simulations (LES) were carried out to investigate the aerodynamic characteristics of a rectangular cylinder with side ratio B/D=5 at Reynolds number Re=22,000 (based on cylinder thickness). Particular attention was devoted to the effects of velocity shear in the oncoming flow. Time-averaged and unsteady flow patterns around the cylinder were studied to enhance understanding of the effects of velocity shear. The simulation results showed that the Strouhal number has no significant variation with oncoming velocity shear, while the peak fluctuation frequency of the drag coefficient becomes identical to that of the lift coefficient with increase in velocity shear. The intermittently-reattached flow that features the aerodynamics of the 5:1 rectangular cylinder in non-shear flow becomes more stably reattached on the high-velocity side, and more stably separated on the low-velocity side. Both the mean and fluctuating drag coefficients increase slightly with increase in velocity shear. The mean and fluctuating lift and moment coefficients increase almost linearly with velocity shear. Lift force acts from the high-velocity side to the low-velocity side, which is similar to that of a circular cylinder but opposite to that of a square cylinder under the same oncoming shear flow.