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A review of the health effects and exposure-responsible relationship of diesel particulate matter for underground mines

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International Journal of Mining Science and Technology 2017年第5期27卷 831-838页

作者： chang Ping xu Guang Department of Mining Engineering and Metallurgical Engineering Western Australian School of MinesCurtin UniversityKalgoorlie 6430Australia

The increasing use of diesel-powered equipment in confined spaces(underground mines) has the potential to over expose underground miners under the threat of diesel particulate matter(DPM). Miners in underground mines can be exposed to DPM concentrations far more than works in other industries. A great number of animal and epidemiological studies have shown that both short-term and long-term DPM exposure have adverse health effect. Based on reviews of related studies, especially some recent evidence, this paper investigated the long and short-term health effects based on animal studies and epidemiological studies. The exposure-response relationship studies were also explored and compared to the current DPM regulation or standards in some countries. This paper found that the DPM health effect studies specifically for miners are not sufficient to draw solid conclusions, and a recommendation limit of DPM concentration can be put in place for better protection of miners from DPM health risk. Current animal studies lack the use of species that have similar lung functions as human for understanding the cancer mode of action in human. And finally, the DPM health hazard will continue to be a challenging topic before the mode of action and reliable exposure-response relationship are established.

关键词： Diesel particulate matter (DPM) Underground mines Lung cancer Exposure-response relationship

Stability and oscillations in a slow-fast flexible joint system with transformation delay

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Acta Mechanica Sinica 2014年第5期30卷 727-738页

作者： shan-Ying Jiang Jian xu Yao Yan School of Aerospace Engineering and Applied Mechanics Tongji University

Flexible joints are usually used to transfer velocities in robot systems and may lead to delays in motion transformation due to joint flexibility. In this paper, a linkrotor structure connected by a flexible joint or shaft is firstly modeled to be a slow-fast delayed system when moment of inertia of the lightweight link is far less than that of the heavy rotor. To analyze the stability and oscillations of the slowfast system, the geometric singular perturbation method is extended, with both slow and fast manifolds expressed analytically. The stability of the slow manifold is investigated and critical boundaries are obtained to divide the stable and the unstable regions. To study effects of the transformation delay on the stability and oscillations of the link, two quantitatively different driving forces derived from the negative feedback of the link are considered. The results show that one of these two typical driving forces may drive the link to exhibit a stable state and the other kind of driving force may induce a relaxation oscillation for a very small delay. However, the link loses stability and undergoes regular periodic and bursting oscillation when the transformation delay is large. Basically, a very small delay does not affect the stability of the slow manifold but a large delay affects substantially.

关键词： Flexible joint - Slow-fast system - Transforma- tion delay Geometric singular perturbation

Electrospun nanofibers of poly(vinyl pyrrolidone)/Eu^(3+) and its photoluminescence properties

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Chinese Chemical Letters 2007年第4期18卷 465-468页

作者： shan shan Tang chang Lu Shao Shou Zhu Li Center for Advanced Optoelectronic Functional Materials Research Northeast Normal University Changchun 130024 PR China

Nanofibers of poly（vinyl pyrrolidone）（PVP）/Eu^3＋ with diameters of 300-900 nm were prepared by using sol-gel processing and electrospinning technique. The products were characterized by scanning electron microscope （SEM）, Fourier transform infrared spectroscopy （FT-IR）, and photoluminescence （PL）. The results indicated that, Eu^3＋ was successfully embedded in the onedimensional hybrid nanofibers, and the PVP/Eu^3＋ hybrid nanofibers had favorable photoluminescence properties.

关键词： Electrospinning Nanofibers PVP Eu^3+

Accurate 3D geometry measurement for non-cooperative spacecraft with an unfocused light-field camera

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Journal of Systems Engineering and Electronics 2022年第1期33卷 11-21页

作者： xu Shengming LU shan HOU Yueyang SHI Shengxian School of Mechanical Engineering Shanghai Jiao Tong UniversityShanghai 200240China shanghai Key Laboratory of Space Intelligent Control Technology Shanghai Aerospace Control Technology InstituteShanghai 201109China

This work explores an alternative 3D geometry measurement method for non-cooperative spacecraft guiding navigation and proximity *** one snapshot of an unfocused light-field camera, the 3D point cloud of a non-cooperative spacecraft can be calculated from sub-aperture images with the epipolar plane image(EPI) based light-field rendering algorithm.A chang'e-3 model(7.2 cm×5.6 cm×7.0 cm) is tested to validate the proposed *** measurement distances(1.0 m, 1.2 m, 1.5 m) are considered to simulate different approaching *** errors are quantified by comparing the light-field camera data with a high precision commercial laser *** mean error distance for the three cases are 0.837 mm, 0.743 mm, and 0.973 mm respectively, indicating that the method can well reconstruct 3D geometry of a non-cooperative spacecraft with a densely distributed 3D point cloud and is thus promising in space-related missions.

关键词： 3D geometry measurement non-cooperative spacecraft unfocused light-field camera

Numerical investigation on free surface effect on the supercavitating flow over a low aspect ratio wedge-shaped hydrofoil

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Journal of Hydrodynamics 2020年第1期32卷 20-30页

作者： chang xu Boo Cheong Khoo Department of Mechanical Engineering National University of SingaporeSingapore

In this study,the effect of the free surface on the supercavitating flow that surrounds a low aspect ratio wedge-shaped hydrofoil is studied based on computational fluid dynamics(CFD),with Cartesian cut-cell mesh *** volume of fraction(VOF)method and the k-ε turbulence model with the Schnerr Sauer cavitation model are used for simulating the supercavitation in turbulent *** quasi-3-D and full-3-D cases are *** quasi-3-D simulation results are compared with the previous water tunnel experimental data and analytical data,and the results agree well with each *** results are presented for a wide range of submerged distance in terms of the free surface effect on the cavity shape,wave elevation and force *** range of the free surface effect is *** simulation results show that the cavitating flow around the hydrofoil become shorter and thicker as the submerge depth *** the aspect ratio of the hydrofoil studied in the full-3-D cases is low,the 3-D effect on the supercavitating flow is *** relationship between the flow patterns and vortex structures is also revealed from the numerical results.

关键词： Supercavitating flow hydrofoil multiphase How free surface effect

Generation of Transgene-free Induced Pluripotent Stem Cells with Non-viral Methods

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Chinese Medical Sciences Journal 2013年第1期28卷 50-54页

作者： Tao Wang Hua-shan Zhao Qiu-ling Zhang chang-lin xu chang-bai Liu Institute of Molecular Biology China Three Georges University Third Clinical Medical School China Three Georges University First Clinical Medical School China Three Georges University Department of Neurosurgery Gezhouba Central HospitalChina Three Georges University Yichang City Central Hospital China Three Georges University

Induced pluripotent stem （iPS） cells were originally generated from mouse fibroblasts by enforced expression of Yamanaka factors （Oct3/4, Sox2, Klf4, and c-Myc）. The technique was quickly re- produced with human fibroblasts or mesenchymal stem cells. Although having been showed therapeutic po- tential in animal models of sickle ceil anemia and Parkinson＇s disease, iPS cells generated by viral methods do not suit all the clinical applications. Various non-viral methods have appeared in recent years for application of iPS cells in cell transplantation therapy. These methods mainly include DNA vector-based approaches, transfection of mRNA, and transduction of reprogramming proteins. This review summarized these non-viral methods and compare the advantages, disadvantages, efficiency, and safety of these methods.

关键词： induced pluripotent stem cells non-viral methods transcription factor re-generative medicine

Boundedness of Some Marcinkiewicz Integral Operators Related to Higher Order Commutators on Hardy Spaces

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Acta Mathematica Sinica,English Series 2006年第1期22卷 105-114页

作者： shan Zhen LU Li Fang xu Department of Mathematics Beijing Normal University Beijing 100875 P. R. China

In this paper, the authors study the boundedness properties of μΩ↑m,b generated by the function b ∈Lipβ（R^n）（0 〈β≤ 1/m） and the Marcinkiewicz integrals operator μΩ. The boundednesses are established on t... 详细信息

关键词： Marcinkiewicz integral Higher order commutator Lipshcitz space Hardy type space Herz space

Asymmetric response of the eastern tropical Indian SST to climate warming and cooling

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Acta Oceanologica Sinica 2019年第5期38卷 76-85页

作者： shan xu Yiyong Luo Fukai Liu College of Oceanic and Atmospheric Sciences Ocean University of China Physical Oceanography Laboratory Ocean University of China

The response of the eastern tropical Indian Ocean(ETIO) to heat fluxes of equal amplitude but opposite sign is investigated using the Community Earth System Model(CESM). A significant positive asymmetry in sea surface temperature(SST) is found over the ETIO—the warming responses to the positive forcing exceeds the cooling to the negative forcing. A mixed layer heat budget analysis is carried out to identify the mechanisms responsible for the SST asymmetry. Results show that it is mainly ascribed to the ocean dynamical processes, including vertical advections and diffusion. The net surface heat flux, on the contrary, works to reduce the asymmetry through its shortwave radiation and latent heat flux components. The former is due to the nonlinear relationship between SST and cloud, while the latter is resulted mainly from Newtonian damping and air-sea stability effects. changes in the SST skewness are also evaluated, with more enhanced negative SST skewness over the ETIO found for the cooling than heating scenarios due to the asymmetric thermocline-SST feedback.

关键词： tropical Indian Ocean SST asymmetry climate warming climate cooling negative SST skewness

Evolutionary Pattern and Effect of Administrative Division Adjustment During Urbanization of China:Empirical Analysis on Multiple Scales

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Chinese Geographical Science 2018年第5期28卷 758-772页

作者： YU Hu DENG Yu xu shan Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Science Key Laboratory of Regional Sustainable Development Modeling Chinese Academy of Science

The adjustment of administrative divisions is one of the important factors guiding China's urbanization, which has profound economic and social effects for regional development. In this paper, we comprehensively describe the process of the adjustment of administrative divisions at provincial and municipal levels in China and summarize the effects on the basic structure and patterns of the spatial development. We quantitatively assess the effects on fields such as urbanization and social economy through the use of multidimensional scaling. The results show that: 1) Upgrading county to municipality(or city-governed district) is the main way of adjusting the administrative divisions. It is also an important factor in the spatial differentiation of interprovincial urbanization. China's population urbanization can be divided into four patterns including interprovincial migration, provincial migration, natural growth, and growth caused by the adjustment of administrative divisions, which is also the main reason for the increased Chinese urbanization rate at the provincial level. 2) Taking the city of Beijing as an example, we generalize five adjustment patterns made to administrative divisions: the set-up of sub-districts, the set-up of regional offices, the upgrading of townships to sub-districts, the upgrading of townships to towns, and the set-up of towns and the addition of new regional offices. We summarize the municipal urban spatial structure, including the sub-district office area in the central urban area, the regional office area in the new urban area, the mixed area of villages, towns, and sub-district offices in the suburb area, and the township area in the outer suburb area. 3) The adjustment of administrative divisions triggers a significant circulative accumulation effect, resulting in the spatial locking of population and industrial agglomeration. It affects the evolution of the urban spatial form and plays an important role in shaping the urban spatial st

关键词： administrative division adjustment evolutionary structure effect evaluation multidimensional scaling urbanization China