作者：
Zou, Bin*;Wilson, J. Gaines;Zhan, F. Benjamin;Zeng, Yongnian
期刊：
Journal of environmental monitoring : JEM,2009年11(3):475-90 ISSN：1464-0325
通讯作者：
Zou, Bin
作者机构：
[Zou, Bin; Zeng, Yongnian] Cent S Univ, Sch Infophys & Geomat Engn, Changsha 410086, Hunan, Peoples R China.;[Zhan, F. Benjamin; Zou, Bin] Texas State Univ, Texas Ctr Geog Informat Sci, Dept Geog, San Marcos, TX 78666 USA.;[Wilson, J. Gaines] Univ Texas Brownsville, Dept Chem & Environm Sci, Brownsville, TX 78520 USA.;[Zhan, F. Benjamin] Wuhan Univ, Sch Resource & Environm Sci, Wuhan 430079, Hubei, Peoples R China.
通讯机构：
[Zou, Bin] Cent S Univ, Sch Infophys & Geomat Engn, Changsha 410086, Hunan, Peoples R China.
摘要：
The assessment of personal exposure to air pollution is a critical component of epidemiological studies associating air pollution and health effects. This paper critically reviewed 157 studies over 29 years that utilized one of five categories of exposure methods (proximity, air dispersion, hybrid, human inhalation, and biomarkers). Proximity models were found to be a questionable technique as they assume that closer proximity equates to greater exposure. Inhalation models and biomarker estimates were the most effective in assessing personal exposure, but are often cost prohibitive for large study populations. This review suggests that: (i) factors such as uncertainty, validity, data availability, and transferability related to exposure assessment methods should be considered when selecting a model; and (ii) although an entirely discreet new class of approach is not necessary, significant progress could be made through the development of a 'hybrid' model utilizing the strengths of several existing methods. Future work should systematically evaluate the performance of hybrid models compared to other individual exposure assessment methods utilizing geospatial information technologies (e.g. geographic information systems (GIS) and remote sensing (RS)) to more robustly refine estimates of ambient exposure and quantify the linkages and differences between outdoor, indoor and personal exposure estimates.
摘要：
A combination of GPS and GLONASS observations can offer improved reliability, availability and accuracy for precise point positioning (PPP). We present and analyze a combined GPS/GLONASS PPP model, including both functional and stochastic components. Numerical comparison and analysis are conducted with respect to PPP based on only GPS or GLONASS observations to demonstrate the benefits of the combined GPS/GLONASS PPP. The observation residuals are analyzed for more appropriate stochastic modeling for observations from different navigation systems. An analysis is also made using different precise orbit and clock products. The performance of the combined GPS/GLONASS PPP is assessed using both static and kinematic data. The results indicate that the convergence time can be significantly reduced with the addition of GLONASS data. The positioning accuracy, however, is not significantly improved by adding GLONASS data if there is a sufficient number of GPS satellites with good geometry.
期刊：
INTERNATIONAL JOURNAL OF GEOGRAPHICAL INFORMATION SCIENCE,2012年26(6):1073-1089(17) ISSN：1365-8824
通讯作者：
Zou, Bin
作者机构：
[Neng Wan] Univ Nebraska Med Ctr, Dept Hlth Serv Res & Adm, Omaha, NE USA.;[Bin Zou] Cent S Univ, Dept Survey Engn & Geomat, Sch Geosci & Infophys, Changsha, Peoples R China.;[Troy Sternberg] Univ Oxford, Sch Geog & Environm, Oxford OX1 2JD, England.
通讯机构：
[Zou, Bin] Cent S Univ, Dept Survey Engn & Geomat, Sch Geosci & Infophys, Changsha, Peoples R China.
关键词：
E2SFCA;GIS;Gravity model;health professional shortage area;health service;spatial access
摘要：
Gravity-based spatial access models have been widely used to estimate spatial access to healthcare services in an attempt to capture the interaction of various factors. However, these models are inadequate in informing health resource allocation work due to their inappropriate assumption of healthcare demand. For the purpose of effective healthcare resource planning, this article proposes a three-step floating catchment area (3SFCA) method to minimize the healthcare-demand overestimation problem. Specifically, a spatial impedance-based competition scheme is incorporated into the enhanced two-step floating catchment area (E2SFCA) method to account for a reasonable model of healthcare supply and demand. A case study of spatial access to primary care physicians along the Austin–San Antonio corridor area in central Texas showed that the proposed method effectively minimizes the overestimation of healthcare demand and reflects a more balanced geographic pattern of spatial access than E2SFCA. In addition, by using an adjusted spatial access index, the 3SFCA method indicates strong potential for identifying health professional shortage areas. The study concludes that 3SFCA is a promising method to provide health professionals and decision makers with useful healthcare accessibility information.
作者机构：
[Zhao, Yu; Hu, Mao-Gui; Wang, Jin-Feng; Xu, Cheng-Dong] Chinese Acad Sci, Inst Geog Sci & Nat Resources Res, State Key Lab Resources & Environm Informat Syst, Beijing, Peoples R China.;[Christakos, George] San Diego State Univ, Dept Geog, San Diego, CA 92182 USA.;[Zhao, Yu] Cent S Univ, Sch Geosci & Infophys, Changsha, Hunan, Peoples R China.
通讯机构：
[Wang, Jin-Feng] Chinese Acad Sci, Inst Geog Sci & Nat Resources Res, State Key Lab Resources & Environm Informat Syst, Beijing, Peoples R China.
关键词：
Air pollution,Pollution,Air quality,Pollutants,Covariance,Environmental protection,Municipal governments,Urban areas
摘要：
There has been discrepancies between the daily air quality reports of the Beijing municipal government, observations recorded at the U.S. Embassy in Beijing, and Beijing residents' perceptions of air quality. This study estimates Beijing's daily area PM(2.5) mass concentration by means of a novel technique SPA (Single Point Areal Estimation) that uses data from the single PM(2.5) observation station of the U.S Embassy and the 18 PM(10) observation stations of the Beijing Municipal Environmental Protection Bureau. The proposed technique accounts for empirical relationships between different types of observations, and generates best linear unbiased pollution estimates (in a statistical sense). The technique extends the daily PM(2.5) mass concentrations obtained at a single station (U.S. Embassy) to a citywide scale using physical relations between pollutant concentrations at the embassy PM(2.5) monitoring station and at the 18 official PM(10) stations that are evenly distributed across the city. Insight about the technique's spatial estimation accuracy (uncertainty) is gained by means of theoretical considerations and numerical validations involving real data. The technique was used to study citywide PM(2.5) pollution during the 423-day period of interest (May 10, 2010 to December 6, 2011). Finally, a freely downloadable software library is provided that performs all relevant calculations of pollution estimation.
摘要：
The usefulness of gravity-based spatial access models is limited because of the uncertainty introduced by the range of values of the impedance coefficient. To solve this problem, this paper proposes the concept of spatial access ratio (SPAR) derived from the enhanced 2-step floating catchment area (E2SFCA) method - a recent extension of the gravity model - to assess potential spatial access. First, a sensitivity assessment is conducted to verify the effectiveness of SPAR and its advantages in overcoming the uncertainty problem. Then, the E2SFCA method and the shortest travel time method are employed to measure potential spatial access to colorectal cancer (CRC) prevention and treatment services in Texas based on data at the census tract level. The socio-demographic and geographic distributions of potential spatial access to CRC services are also examined. The sensitivity assessment reveals substantial fluctuations in the values of the spatial access index calculated directly by the E2SFCA method under different values of the impedance coefficient. However, the values of SPAR remain stable under different values of the coefficient. A comparative analysis indicates that potential spatial access to primary care physicians (PCPs), CRC screening facilities, and oncologists varied among different racial/ethnic and socioeconomic population groups as well as in different geographic regions in Texas. Non-Hispanic blacks, Asians, and people in affluent areas had a geographical advantage in accessing CRC services than other groups. The urban/rural difference was more obvious and serious than those of different racial/ethnic groups and groups with different socio-economic statuses, as metropolitan residents had more than three times the potential spatial access than isolated rural residents. (C) 2011 Elsevier Ltd. All rights reserved.
作者机构：
[Li, Z. W.; Sun, Q.; Hu, J.; Zhu, J. J.] Cent S Univ, Sch Geosci & Infophys, Changsha 410083, Hunan, Peoples R China.;[Ding, X. L.; Zhang, L.] Hong Kong Polytech Univ, Dept Land Surveying & Geoinformat, Kowloon, Hong Kong, Peoples R China.
通讯机构：
[Li, Z. W.] Cent S Univ, Sch Geosci & Infophys, Changsha 410083, Hunan, Peoples R China.
摘要：
One-dimensional measurement along the Line-Of-Sight (LOS) direction has greatly limited the capability of InSAR technique in the investigation of surface displacements and their dynamics. In recent years, great efforts have been made to resolve complete three-dimensional (3-D) displacements from InSAR measurements. This contribution is intended to provide a systematic review of the progress achieved in this field. Based on an analysis of the InSAR LOS measurements, we first cover two commonly used techniques, i.e., Offset-Tracking and multi-aperture InSAR (MAI), with which the surface displacement in the azimuth direction can be measured together with the LOS displacement. Several methods for mapping 3-D displacements using InSAR measurements are subsequently presented and categorized into three groups: (i) combination of multi-pass LOS and azimuth measurements; (ii) integration of InSAR and GPS data; and (iii) prior information assisted approaches. The strengths and weaknesses of each method are analyzed to show the applicability of each method to specific 3-D displacement mapping cases, in hope to provide a useful guidance in choosing a suitable approach accordingly. Finally, suggestions for resolving the challenging issues and outlook of future research are given. (c) 2014 Elsevier B.V. All rights reserved.
期刊：
International Journal for Numerical and Analytical Methods in Geomechanics,2010年34(17):1767-1796 ISSN：1096-9853
通讯作者：
Zhao, Chongbin
作者机构：
[Zhao, Chongbin] Cent S Univ, Computat Geosci Res Ctr, Changsha 410083, Peoples R China.;[Hobbs, B. E.; Ord, A.] Univ Western Australia, Sch Earth & Environm, Crawley, WA 6009, Australia.;[Hobbs, B. E.; Ord, A.] CSIRO, Div Explorat & Min, Bentley, WA 6102, Australia.
通讯机构：
[Zhao, Chongbin] Cent S Univ, Computat Geosci Res Ctr, Changsha 410083, Peoples R China.
关键词：
nonaqueous phase liquid;residual saturation;NAPL dissolution;front instability;reactive mass transport;porous media
通讯机构：
[Sun, Ya] Cent S Univ, Sch Geosci & Infophys, Changsha, Hunan, Peoples R China.
关键词：
SE Tibetan plateau;crustal anisotropy;lower crustal flow;depth varying deformation
摘要：
We analyze a large amount of receiver function data recorded by regional seismic networks of the China Earthquake Administration to estimate crustal structure and deformation beneath the southeast margin of the Tibetan plateau and its surrounding areas. We develop a comprehensive analysis method that facilitates robust extraction of azimuthal seismic anisotropy from receiver function data. The method includes an estimate of fast polarization direction and splitting time by a joint analysis of radial and transverse receiver function data, and an evaluation of measurement reliability by statistical and harmonic analysis. We find significant seismic anisotropy with a splitting time of 0.5-0.9 s beneath the SE margin of the Tibetan plateau. Both the splitting time and fast polarization direction are comparable to those estimated from SKS/SKKS data, suggesting that crustal anisotropy is the main cause of shear wave splitting of the SKS/SKKS wave. This also suggests that deformation in the upper mantle is either weak or predominantly vertical, and is obviously different from the one in the crust. A vertical flow in the upper mantle, combined with the observation of a thin lithosphere beneath the study area, leads to the inference that part of the mantle lithosphere may have been removed and is descending into deep mantle. Stations located in the surrounding areas, on the other hand, exhibit very little to no crustal anisotropy. The estimated Moho depth and Vp/Vs ratio also show a distinct difference between the SE Tibetan plateau and the surrounding regions. Stations on the Tibetan plateau have a Vp/Vs ratio of similar to 1.79, which is substantially higher than those measured at the Yunnan-Guizhou (Yungui) plateau (similar to 1.69). Our observations here are consistent with the scenario that the SE Tibet has been built by lower crustal flow. They also suggest that the mantle lithosphere beneath the margin may have been mechanically decoupled from the upper crust. (C) 2012 Elsevier B.V. All rights reserved.
作者：
Feng, GuangCai*;Hetland, Eric A.;Ding, XiaoLi;Li, ZhiWei;Zhang, Lei
期刊：
Geophysical Research Letters,2010年37(1):- ISSN：1944-8007
通讯作者：
Feng, GuangCai
作者机构：
[Ding, XiaoLi; Feng, GuangCai; Zhang, Lei] Hong Kong Polytech Univ, Dept Land Surveying & Geoinformat, Kowloon, Hong Kong, Peoples R China.;[Hetland, Eric A.] Univ Michigan, Dept Geol Sci, Ann Arbor, MI 48109 USA.;[Li, ZhiWei] Cent S Univ, Dept Geomat, Changsha 410083, Peoples R China.
通讯机构：
[Feng, GuangCai] Hong Kong Polytech Univ, Dept Land Surveying & Geoinformat, Kowloon, Hong Kong, Peoples R China.
关键词：
coseismic slip;InSAR;earthquake
摘要：
[1] We infer co‐seismic fault slip during the 2008 Mw 7.9 Wenchuan earthquake from interferometric synthetic aperture radar (InSAR) and GPS observations of ground deformation. We use ALOS/PALSAR data from ascending orbits on six tracks, and we do not use data that are strongly affected by ionospheric perturbations. We use a fault model composed of three planar fault segments of the Beichuan fault, and one planar segment representing the parallel Pengguan fault. Maximum thrust‐slip is up to 6.7 m near the surface, and occurs in two locations, near Yingxiu in the south and Beichuan in the center of the rupture. Maximum strike‐slip is over 4 m, and occurs near Pingtong and Nanba along the northern end of the rupture. We find that the ratio of coseismic thrust‐ to strike‐slip on the Beichuan fault decreases from 1.5 to 0.7 from the SW to the NE.
摘要：
Schizophrenia is a severe mental illness associated with the symptoms such as hallucination and delusion. The objective of this study was to investigate the abnormal resting-state functional connectivity patterns of schizophrenic patients which could identify furthest patients from healthy controls. The whole-brain resting-state fMRI was performed on patients diagnosed with schizophrenia (n = 22) and on age- and gender-matched, healthy control subjects (n = 22). To differentiate schizophrenic individuals from healthy controls, the multivariate classification analysis was employed. The weighted brain regions were got by reconstruction arithmetic to extract highly discriminative functional connectivity information. The results showed that 93.2% (p < 0.001) of the subjects were correctly classified via the leave-one-out cross-validation method. And most of the altered functional connections identified located within the visual cortical-, default-mode-, and sensorimotor network. Furthermore, in reconstruction arithmetic, the fusiform gyrus exhibited the greatest amount of weight. This study demonstrates that schizophrenic patients may be successfully differentiated from healthy subjects by using whole-brain resting-state fMRI, and the fusiform gyrus may play an important functional role in the physiological symptoms manifested by schizophrenic patients. The brain region of great weight may be the problematic region of information exchange in schizophrenia. Thus, our result may provide insights into the identification of potentially effective biomarkers for the clinical diagnosis of schizophrenia.
作者机构：
[Feng, Guangcai; Zhu, Jianjun; Li, Zhiwei] Cent S Univ, Sch Geosci & Infophys, Lab Radar Remote Sensing, Changsha 410083, Hunan, Peoples R China.;[Shan, Xinjian; Zhang, Guohong] China Earthquake Adm, Inst Geol, State Key Lab Earthquake Dynam, Beijing 100029, Peoples R China.;[Zhang, Lei] Hong Kong Polytech Univ, Dept Land Surveying & Geoinformat, Kowloon, Hong Kong, Peoples R China.
通讯机构：
[Li, Zhiwei] Cent S Univ, Sch Geosci & Infophys, Lab Radar Remote Sensing, Changsha 410083, Hunan, Peoples R China.
关键词：
Satellite geodesy;Radar interferometry;Earthquake source observations;Seismicity and tectonics
摘要：
We map the complete surface deformation of 2015 M-w 7.8 Gorkha Nepal earthquake and its M-w 7.3 aftershock with two parallel ALOS2 descending ScanSAR paths' and two ascending Stripmap paths' images. The coseismic fault-slip model from a combined inversion of InSAR and GPS data reveals that this event is a reverse fault motion, with a slight right-lateral strike-slip component. The maximum thrust-slip and right-lateral strike-slip values are 5.7 and 1.2 m, respectively, located at a depth of 7-15 km, southeast to the epicentre. The total seismic moment 7.55 x 10(20) Nm, corresponding to a moment magnitude M-w 7.89, is similar to the seismological estimates. Fault slips of both the main shock and the largest aftershock are absent from the upper thrust shallower than 7 km, indicating that there is a locking lower edge of Himalayan Main Frontal Thrust and future seismic disaster is not unexpected in this area. We also find that the energy released in this earthquake is much less than the accumulated moment deficit over the past seven centuries estimated in previous studies, so the region surrounding Kathmandu is still under the threaten of seismic hazards.
