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Comparative Analysis for the Detection and Monitoring of Mycoplasma hyopneumoniae Infection by Nested PCR(n-PCR) and Real time PCR(q-PCR) from Field Swine Herds 被引量:2
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作者 William Keeru KIMARU 白方方 +6 位作者 武昱孜 Joyce Wanjiru MAINGI 华利忠 刘茂军 张旭 邵国青 鲍恩东 《Agricultural Science & Technology》 CAS 2014年第6期918-921,共4页
[Objective] 303 nasal swabs samples were collected from pigs in farms located in Taizhou city, Jiangsu Province, China from March to December 2012 for the purpose of detecting the presence of Mycoplasma hyopneumoniae,... [Objective] 303 nasal swabs samples were collected from pigs in farms located in Taizhou city, Jiangsu Province, China from March to December 2012 for the purpose of detecting the presence of Mycoplasma hyopneumoniae, the primary agent of Enzootic porcine pneumonia (EPP) in pig herds using the nested PCR and Real time PCR techniques. [Method] Nasal swabs were collected from pigs of different ages' i.e. 7, 14, 21, 28, 30 and 35 days old, soaked in sterile 1 xPBS overnight at 4 ℃ and DNA extracted using the TIANamp(R) bacterial DNA kit. The DNA samples underwent amplification under the Mhyo 183 q-PCR and P36 primer Nested PCR systems. [Result] With the Nested PCR assay, 38 (12.5%) out of 303 samples tested positive for the presence of M. hyopneumoniae; with the real time PCR assay 152 (50.2%) tested positive for M. hyopneumoniae. The two assays matched to positively detect Mhyo in 22 (7.3%) samples and again matched in 127 (41.9%) samples negative for Mhyo infection. The pattern of infection in both assays was similar where 7- and 35-day-old piglets in both assays had the highest rates of infection i.e. 15.6% and 18.4% for n-PCR and 53.1% and 56.6% for q-PCR for 7- and 35-day-old piglets respectively. [Conclusion] The results highlight the suitability of both PCR assays in establishing the herd infection status of pigs in field conditions. 展开更多
关键词 Enzootic porcine pneumonia INFECTION Mycoplasma hyopneumoniae PCR
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A structural relationship between place attachment and intention to conserve landscapes–a case study of Harz National Park in Germany 被引量:4
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作者 Dukjae LEE Ju-Hyoung LEE 《Journal of Mountain Science》 SCIE CSCD 2017年第5期998-1007,共10页
Place attachment is an important motivation for people to spend more time outdoors and to protect landscapes.This study explores visitors' intention to conserve natural landscapes based on the relationship with th... Place attachment is an important motivation for people to spend more time outdoors and to protect landscapes.This study explores visitors' intention to conserve natural landscapes based on the relationship with their place attachment to National Park landscape. Structural equation modelling(SEM) was used to determine the relationship between landscape conservation and place attachment. A survey with a structured questionnaire was administered to visitors to the seven designated hiking courses of Harz National Park in Germany. The path coefficient of 0.77 revealed that place dependence positively and significantly affected place attachment, whereas place identity did not. Place attachment had a significant effect on both affective appraisals and visiting satisfaction. Higher place attachment led to higher emotional reaction to landscapes on site and higher satisfaction of visiting the park. Among the variables, visiting satisfaction, but not affective appraisals, played a statistically significant mediating role between place attachment and conservation intention. With a path coefficient of 0.86, conservation intention was highly affected by visiting satisfaction. These results suggest that the managers of National Parks should focus on increasing visiting satisfaction based on how visitors are emotionally bonded with their visiting places, in order to enhance the intentions to conserve the landscape of the visitors to National Parks. 展开更多
关键词 Place attachment Sense of place Mountain forests Structural Equation Model Landscape preference
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Did Ecological Engineering Projects Have a Significant Effect on Large-scale Vegetation Restoration in Beijing-Tianjin Sand Source Region, China? A Remote Sensing Approach 被引量:6
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作者 LI Xiaosong WANG Hongyan +2 位作者 ZHOU Shufang SUN Bin GAO Zhihai 《Chinese Geographical Science》 SCIE CSCD 2016年第2期216-228,共13页
Aiming for the restoration of degraded ecosystems, many ecological engineering projects have been implemented around the world. This study investigates the ecological engineering project effectiveness on vegetation re... Aiming for the restoration of degraded ecosystems, many ecological engineering projects have been implemented around the world. This study investigates the ecological engineering project effectiveness on vegetation restoration in the Beijing-Tianjin Sand Source Region(BTSSR) from 2000 to 2010 based on the rain use efficiency(RUE) trend in relation to the land cover. More than half of the BTSSR experienced a vegetation productivity increase from 2000 to 2010, with the increasing intensity being sensitive to the indicators chosen. A clear tendency towards smaller increasing areas was shown when using the net primary productivity(NPP, 51.30%) instead of the accumulated normalized difference vegetation index(59.30%). The short-term variation in the precipitation and intra-seasonal precipitation distribution had a great impact on the remote sensing-based vegetation productivity. However, the residual trends method(RESTREND) effectively eliminated this correlation, while incorporating the variance and skewness of the precipitation distribution increased the models′ ability to explain the vegetation productivity variation. The RUE combined with land cover dynamics was valid for the effectiveness assessment of the ecological engineering projects on vegetation restoration. Particularly, the result based on growing season accumulated normalized difference vegetation index(ΣNDVI) residuals was the most effective, showing that 47.39% of the BTSSR experienced vegetation restoration from 2000 to 2010. The effectiveness of the ecological engineering projects differed for each subarea and was proportional to the strength of ecological engineering. The water erosion region dominated by woodland showed the best restoration, followed by the wind-water erosion crisscross regions, while the wind erosion regions dominated by grassland showed the worst effect. Seriously degraded regions still cover more area in the BTSSR than restored regions. Therefore, more future effort should be put in restoring degraded land. 展开更多
关键词 vegetation restoration ecological engineering rain use efficiency(RUE) residual trends method(RESTREND) Beijing-Tianjin Sand Source Region(BTSSR)
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Perceived Influence of Toothpaste Repackaging on Purchase Predisposition of Customers in Owo, Ondo State
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作者 Kolade Ajilore Christiana Shade Ade-Johnson 《Journalism and Mass Communication》 2016年第5期287-301,共15页
Packaging has advanced from being preserver of products to being a visible billboard and a silent salesman for products. This has made the manufacturers to keep repackaging their products especially toothpaste. The pa... Packaging has advanced from being preserver of products to being a visible billboard and a silent salesman for products. This has made the manufacturers to keep repackaging their products especially toothpaste. The paper therefore examines perceived influence of the toothpaste repackaging on the purchase predisposition of the residents of Owo Local Government Area using Mymy, Close Up, Macleans and Pepsodent as case study. Survey design was employed for the study while two hundred copies of questionnaire were administered to two hundred respondents who were selected through purposive sampling. The finding revealed that there is significant influence of change in packaging of tooth paste on the consumers' purchase predisposition which may invariably lead to purchase of these brands of tooth paste. The study therefore recommends that manufacturers should introduce changes in elements of tooth paste carefully and gradually in order to study the consumers' reaction to such change. 展开更多
关键词 PACKAGING repackaging consumer behaviour view model
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Spatial Structure and Land Use Control in Extended Metropolitan Region of Zhujiang River Delta,China 被引量:4
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作者 DAI Junliang WANG Kaiyong GAO Xiaolu 《Chinese Geographical Science》 SCIE CSCD 2010年第4期298-308,共11页
The Zhujiang (Pearl) River Delta is one of the most developed Extended Metropolitan Regions (EMR) in China.With the rapid urbanization,the agglomeration of population and industries has emerged,which has led to dramat... The Zhujiang (Pearl) River Delta is one of the most developed Extended Metropolitan Regions (EMR) in China.With the rapid urbanization,the agglomeration of population and industries has emerged,which has led to dramatic changes of spatial structure and land use in this region.With data of high resolution TM remote sensing images and Google Earth maps,this paper identified and analyzed the spatial pattern of the Zhujiang River Delta EMR using Envy and ArcGIS tools.It was found that 1) the industrial land uses were expanding substantially,particularly on the bank sides of the Zhujiang River estuary;2) large-scale housing developments were concentrated in the fringe of metropolitan areas such as those of Guangzhou and Shenzhen;3) a regional transportation network with the spatial pattern of ″1 circle +2 pieces + 3 axes″ had significantly affected the location choice of manufacture enterprises.At the same time,both highly specialized land use and severely mixed land use patterns were identified.As a consequence of the latter,land use efficiency of the whole EMR areas was reduced.Moreover,ecologic and environmental problems were severe.Based on the above analysis,suggestions were given from the viewpoint of spatial safety,land use efficiency,and the reorganization of spatial structure in the Zhujiang River Delta EMR. 展开更多
关键词 spatial pattern agglomeration and expansion spatial expansion Extended Metropolitan Region (EMR) Zhujiang River Delta (Pearl River Delta)
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Increase of Local Seismicity Due to the Construction of Taipei 101?
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作者 Jiang Changsheng Wu Zhongliang 《Earthquake Research in China》 2007年第2期156-162,共7页
Considering the controversy over whether the Taipei 101 skyscraper has induced an increase of local seismicity, we reanalyzed the local earthquake catalogue before and after the construction to investigate whether the... Considering the controversy over whether the Taipei 101 skyscraper has induced an increase of local seismicity, we reanalyzed the local earthquake catalogue before and after the construction to investigate whether the reported seismicity increase related to the construction is statistically significant. Statistical tests obtained a positive conclusion about the apparent seismicity increase. However, the calculation of maximum ACFS shows that at most a 2.2 × 10^-4 bar Coulomb Failure Stress change was produced by the construction. Therefore, whether the construction of Taipei 101 really triggered the increase of seismicity still remains an open question: Statistically-yes; physically-no. 展开更多
关键词 Statistical evaluation Taipei 101 Induced seismicity CFS
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Application of the Third Theory of Quantification in Screening Sensitive Geological Factors Influencing Coal and Gas Outburst 被引量:2
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作者 吴财芳 曾勇 张许良 《Journal of China University of Mining and Technology》 2003年第1期66-71,共6页
The principles of the third theory of quantification were discussed. The concept and calculation method of reaction degree were put forward, which have extended the applying range and scientificalness of the primary r... The principles of the third theory of quantification were discussed. The concept and calculation method of reaction degree were put forward, which have extended the applying range and scientificalness of the primary reaction. Taking the Zhongmacun mine as an example, the geological factors affecting coal and gas outburst were researched. Eight sensitive factors for the outburst of coal and gas were screened out from 11 geological factors using the method of unit classification and the third theory of quantification. On the basis of this, the Zhongmacun coal mine was classified into several divisions. The practice shows that it is feasible to apply the third theory of quantification to gas geology, which offers a new thought to screen the sensitive geological factors of gas outburst forecast. 展开更多
关键词 the third theory of quantification reaction degree sensitive geological factor gas outburst forecast
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浅析美食短视频对城市形象的塑造
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作者 齐永光 张瑛君 杨彬 《新闻战线》 2024年第18期92-93,共2页
以沉浸式结构和碎片化的传播方式为基础的移动短视频,丰富了城市形象的书写方式和展示维度。拥有主观能动性的用户通过美食短视频进行情感表达和个体记忆书写,参与到城市相关记忆建构与重塑过程中,以个人视角的“微”记录参与塑造城市... 以沉浸式结构和碎片化的传播方式为基础的移动短视频,丰富了城市形象的书写方式和展示维度。拥有主观能动性的用户通过美食短视频进行情感表达和个体记忆书写,参与到城市相关记忆建构与重塑过程中,以个人视角的“微”记录参与塑造城市的“地方”感,并通过搜索、发布、分享的形式让“地方感”得以丰富延续。 展开更多
关键词 美食短视频 城市形象 “地方”感
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The Impact of Tax Policies on Taxpayers Budget in Terms of Risk, Sensitivity and Volatility
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作者 Bolos Marcel loan Otgon Cristian loan Pop Razvan Valentin 《Chinese Business Review》 2011年第11期1043-1060,共18页
Local and central governments are concerned to develop fiscal policies that are based on principles already enshrined in the literature as the principle of equity and/or the principle of fiscal appropriateness. Beyond... Local and central governments are concerned to develop fiscal policies that are based on principles already enshrined in the literature as the principle of equity and/or the principle of fiscal appropriateness. Beyond these principles, the governments want to make sure that all taxpayers have the capacity to pay at maturity the tax debts owed to the public budget. In crisis situations, as recent experience has shown, governments adopt fiscal policy measures, with the sole purpose of procuring financial resources to cover the huge government budget deficits. In this situation, a natural question arises: Do governments need, for the elaboration of their fiscal policy, an analysis that takes into account the taxpayer's budget? Or is it sufficient that they confine only to the theoretical principles enshrined in the literature or the tax paying ability of the taxpayers? The answer can only be affirmative, because any taxpayer's budget is an inexhaustible source of resources for the public budgets. It is undisputed that in the taxpayer's budget, the tax expenditures coexist with other categories of expenditures such as consumption expenditures, durable expenditures and public utilities expenditures. Each expenditure type is risk-bearing. To study the structure of budget expenditures within the taxpayer, the authors suggest the use of three indicators innovative for the science of public finance: the risk, the sensitivity coefficient and the coefficient of volatility. Depending on the values registered by the three indicators of fiscal policies, expenditures can be classified as risky, volatile and sensitive which may lead to risks of failure to collect the taxes and/or to tax evasion. Innovative for the science of public finances is that the fundamentation of the fiscal policies is realized using the three indicators, the budget of the taxpayer and the networking between the categories of expenditures that fall within its budget structure 展开更多
关键词 fiscal policy RISK VOLATILITY sensitivity taxpayer budget expenditure
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Classification Method Research to Remote Sensing Images
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作者 乔玉良 《Journal of Measurement Science and Instrumentation》 CAS 2010年第4期317-322,共6页
With rapid development of remote sensing technology, the resolution of remote sensing images is increasingly improved; then people can extract more useful data and information from these images. Thus, an important inf... With rapid development of remote sensing technology, the resolution of remote sensing images is increasingly improved; then people can extract more useful data and information from these images. Thus, an important information extraction method from remote sensing images - image classification, becomes more and more important. Based on phenopthase and band composition characteristics, this paper firstly discusses the important role of background parameters in remote sensing images classification; then based on geographical infomation system technology, the computerized automatic classification to high-medium-low-yield croplands in Dingxiang County of Shanxi Province in rotate sensing images has been carried out by using eompound layers classification method of multi-thematic information; compared the classification result to the visual interpretation results, the accuracy increases from 70% to above 90%. 展开更多
关键词 remote sensing classification background parameters thematic information band composition geographical infomation system
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Influences of Sense of Place on Farming Households' Relocation Willingness in Areas Threatened by Geological Disasters:Evidence from China 被引量:3
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作者 Dingde Xu Li Peng +3 位作者 Shaoquan Liu Chunjiang Su Xuxi Wang Tiantian Chen 《International Journal of Disaster Risk Science》 SCIE CSCD 2017年第1期16-32,共17页
Scholars from environmental psychology,geography, disaster science, and sociology have recently focused attention on evacuation and relocation behaviors and influencing factors in hazard-threatened areas. However, exi... Scholars from environmental psychology,geography, disaster science, and sociology have recently focused attention on evacuation and relocation behaviors and influencing factors in hazard-threatened areas. However, existing studies are mainly focused on developed countries and the influence of individual characteristics,household characteristics, and the perception of risk of urban households on evacuation and relocation behaviors.Few studies examine developing countries and the influence of farmers' sense of place in geological hazardthreatened areas. Using statistics of farming households in an area threatened by landslides, this is a pilot study to explore the relationship of sense of place to the relocation willingness of farming households while controlling for other variables. The results show that:(1) Households with higher scores of place identity and place dependence are less willing to relocate, whereas place attachment has no significant relationship to household relocation willingness;(2) Risk perception dimensions, including probability,threat, and controllability have a significant relationship to household relocation willingness, while worry and fear of the unknown have no significant relationship;(3) Household characteristics, including income, whether a household has experienced economic loss from landslides, and social support are significantly correlated with household relocation willingness, while gender, age, experience, distance to hazard sites, size of household, children, older people, and housing material are not. The results for information and education are not robust. This study contributes to the current literature by improving the understanding of the relationship of sense of place to the relocation willingness of farming households in villages threatened by geological disasters in rural China. 展开更多
关键词 China Farming households Relocation willingness Risk perception Sense of place Three Gorges Reservoir area
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Progresses on microwave remote sensing of land surface parameters 被引量:25
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作者 SHI JianCheng DU Yang +15 位作者 DU JinYang JIANG LingMei CHAI LinNa MAO KeBiao XU Peng NI WenJian XIONG Chuan LIU Qiang LIU ChenZhou GUO Peng CUI Qian LI YunQing CHEN Jing WANG AnQi LUO HeJia WANG YinHui 《Science China Earth Sciences》 SCIE EI CAS 2012年第7期1052-1078,共27页
Highly accurate observations at various scales on the land surface are urgently needed for the studies of many areas,such as hydrology,meteorology,and agriculture.With the rapid development of remote sensing technique... Highly accurate observations at various scales on the land surface are urgently needed for the studies of many areas,such as hydrology,meteorology,and agriculture.With the rapid development of remote sensing techniques,remote sensing has had the capacity of monitoring many factors of the Earth's land surface.Especially,the space-borne microwave remote sensing systems have been widely used in the quantitative monitoring of global snow,soil moisture,and vegetation parameters with their all-weather,all-time observation capabilities and their sensitivities to the characteristics of land surface factors.Based on the electromagnetic theories and microwave radiative transfer equations,researchers have achieved great successes in the microwave remote sensing studies for different sensors in recent years.This article has systematically reviewed the progresses on five research areas including microwave theoretical modeling,microwave inversion on soil moisture,snow,vegetation and land surface temperatures.Through the further enrichment of remote sensing datasets and the development of remote sensing theories and inversion techniques,remote sensing including microwave remote sensing will play a more important role in the studies and applications of the Earth systems. 展开更多
关键词 microwave remote sensing soil moisture VEGETATION snow water equivalent land surface temperature
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The backward bifurcation of a model for malaria infection 被引量:4
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作者 Juan Wang Xue-Zhi Li Souvik Bhattacharya 《International Journal of Biomathematics》 SCIE 2018年第2期65-82,共18页
In this paper, an epidemic model of a vector-borne disease, namely, malaria, is consi- dered. The explicit expression of the basic reproduction number is obtained, the local and global asymptotical stability of the di... In this paper, an epidemic model of a vector-borne disease, namely, malaria, is consi- dered. The explicit expression of the basic reproduction number is obtained, the local and global asymptotical stability of the disease-free equilibrium is proved under certain conditions. It is shown that the model exhibits the phenomenon of backward bifurcation where the stable disease-free equilibrium coexists with a stable endemic equilibrium. Further, it is proved that the unique endemic equilibrium is globally asymptotically stable under certain conditions. 展开更多
关键词 Host-vector disease model basic reproduction number EQUILIBRIUM backwardbifurcation global stability.
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Comparative evaluation of geological disaster susceptibility using multi-regression methods and spatial accuracy validation 被引量:14
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作者 蒋卫国 饶品增 +2 位作者 曹冉 唐政洪 陈坤 《Journal of Geographical Sciences》 SCIE CSCD 2017年第4期439-462,共24页
Geological disasters not only cause economic losses and ecological destruction, but also seriously threaten human survival. Selecting an appropriate method to evaluate susceptibility to geological disasters is an impo... Geological disasters not only cause economic losses and ecological destruction, but also seriously threaten human survival. Selecting an appropriate method to evaluate susceptibility to geological disasters is an important part of geological disaster research. The aims of this study are to explore the accuracy and reliability of multi-regression methods for geological disaster susceptibility evaluation, including Logistic Regression(LR), Spatial Autoregression(SAR), Geographical Weighted Regression(GWR), and Support Vector Regression(SVR), all of which have been widely discussed in the literature. In this study, we selected Yunnan Province of China as the research site and collected data on typical geological disaster events and the associated hazards that occurred within the study area to construct a corresponding index system for geological disaster assessment. Four methods were used to model and evaluate geological disaster susceptibility. The predictive capabilities of the methods were verified using the receiver operating characteristic(ROC) curve and the success rate curve. Lastly, spatial accuracy validation was introduced to improve the results of the evaluation, which was demonstrated by the spatial receiver operating characteristic(SROC) curve and the spatial success rate(SSR) curve. The results suggest that: 1) these methods are all valid with respect to the SROC and SSR curves, and the spatial accuracy validation method improved their modelling results and accuracy, such that the area under the curve(AUC) values of the ROC curves increased by about 3%–13% and the AUC of the success rate curve values increased by 15%–20%; 2) the evaluation accuracies of LR, SAR, GWR, and SVR were 0.8325, 0.8393, 0.8370 and 0.8539, which proved the four statistical regression methods all have good evaluation capability for geological disaster susceptibility evaluation and the evaluation results of SVR are more reasonable than others; 3) according to the evaluation results of SVR, the central-southern Yunnan Province are the highest sus-ceptibility areas and the lowest susceptibility is mainly located in the central and northern parts of the study area. 展开更多
关键词 geological disaster susceptibility multi-regression methods geographical weighted regression sup-port vector regression spatial accuracy validation Yunnan Province
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Remote sensing-based artificial surface cover classification in Asia and spatial pattern analysis 被引量:13
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作者 KUANG WenHui CHEN LiJun +6 位作者 LIU JiYuan XIANG WeiNing CHI WenFeng LU DengSheng YANG TianRong PAN Tao LIU AiLin 《Science China Earth Sciences》 SCIE EI CAS CSCD 2016年第9期1720-1737,共18页
Artificial surfaces, characterized with intensive land-use changes and complex landscape structures, are important indicators of human impacts on terrestrial ecosystems. Without high-resolution land-cover data at cont... Artificial surfaces, characterized with intensive land-use changes and complex landscape structures, are important indicators of human impacts on terrestrial ecosystems. Without high-resolution land-cover data at continental scale, it is hard to evaluate the impacts of urbanization on regional climate, ecosystem processes and global environment. This study constructed a hierarchical classification system for artificial surfaces, promoted a remote sensing method to retrieve subpixel components of artificial surfaces from 30-m resolution satellite imageries(Globe Land30) and developed a series of data products of high-precision urban built-up areas including impervious surface and vegetation cover in Asia in 2010. Our assessment, based on multisource data and expert knowledge, showed that the overall accuracy of classification was 90.79%. The mean relative error for the impervious surface components of cities was 0.87. The local error of the extracted information was closely related to the heterogeneity of urban buildings and vegetation in different climate zones. According to our results, the urban built-up area was 18.18×104 km2, accounting for 0.59% of the total land surface areas in Asia; urban impervious surfaces were 11.65×104 km2, accounting for 64.09% of the total urban built-up area in Asia. Vegetation and bare soils accounted for 34.56% of the urban built-up areas. There were three gradients: a concentrated distribution, a scattered distribution and an indeterminate distribution from east to west in terms of spatial pattern of urban impervious surfaces. China, India and Japan ranked as the top three countries with the largest impervious surface areas, which respectively accounted for 32.77%, 16.10% and 11.93% of the urban impervious surface area of Asia. We found the proportions of impervious surface and vegetation cover within urban built-up areas were closely related to the economic development degree of the country and regional climate environment. Built-up areas in developed countries had relatively low impervious surface and high public green vegetation cover, with 50–60% urban impervious surfaces in Japan, South Korea and Singapore. In comparison, the proportion of urban impervious surfaces in developing countries is approaching or exceeding 80% in Asia. In general, the composition and spatial patterns of built-up areas reflected population aggregation and economic development level as well as their impacts on the health of the environment in the sub-watershed. 展开更多
关键词 Artificial surface cover CITY Impervious surface Vegetation cover Remote sensing classification ASIA
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Analysis of a sex-structured HIV/AIDS model with the effect of screening of infectives 被引量:1
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作者 S. Athithan Mini Ghosht 《International Journal of Biomathematics》 2014年第5期103-117,共15页
This paper presents a nonlinear sex-structured mathematical model to study the spread of HIV/AIDS by considering transmission of disease by heterosexual contact. The epidemic threshold and equilibria for the model are... This paper presents a nonlinear sex-structured mathematical model to study the spread of HIV/AIDS by considering transmission of disease by heterosexual contact. The epidemic threshold and equilibria for the model are determined, local stability and global stability of both the “Disease-Free Equilibrium” (DFE) and “Endemic Equilibrium” (EE) are discussed in detail. The DFE is shown to be locally and globally stable when the basic reproductive number R0 is less than unity. We also prove that the EE is locally and globally asymptotically stable under some conditions. Finally, numerical simulations are reported to support the analytical findings. 展开更多
关键词 HIV AIDS HETEROSEXUAL global stability simulation
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Research on Auto-Classification Method of Remote Sensing Images in Mountainous Areas——An Application in Southwest of China
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作者 冯朝阳 张淑敏 +2 位作者 张宝雷 吕世海 高吉喜 《Geo-Spatial Information Science》 2009年第3期191-196,共6页
In mountainous areas, it is the undulant terrain, various types of geomorphic and land use that make the remote sensing images great metamorphism. Moreover, due to the elevation, there are many areas covered with shad... In mountainous areas, it is the undulant terrain, various types of geomorphic and land use that make the remote sensing images great metamorphism. Moreover, due to the elevation, there are many areas covered with shadow, clouds and snow that make the images more inaccurate. As a result, it would be very difficult to carry out auto-classification of RS images in these areas. The study took Southwest China as the case study area and the TM images, SPOT images as the basic information sources assisted by the auxiliary data of DEM, NDVl, topographical maps and soil maps to preprocess the images. After preprocessing by topographic correction and wiping off clouds, snow and shadows, all the image data were stacked together to form the images to be classified. Then, the research used segmentation technology and hierarchical method to extract the main types of land use in the area automatically. The results indicated that the qualitative accuracies of all types of land use extracted in Southwest China were above 90 percent, and the quantitative accuracies was above 86 percent. The goal of reducing workloads had been realized. 展开更多
关键词 SEGMENTATION hierarchical method auto-classification mountainous areas Southwest of China
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THE DYNAMICS OF A DISCRETE SEIT MODEL WITH AGE AND INFECTION AGE STRUCTURES
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作者 HUI CAO YANNI XIAO YICANG ZHOU 《International Journal of Biomathematics》 2012年第3期61-76,共16页
Age and infection age have significant influence on the transmission of infectious dis- eases, such as HIV/AIDS and TB. A discrete SEIT model with age and infection age structures is formulated to investigate the dyna... Age and infection age have significant influence on the transmission of infectious dis- eases, such as HIV/AIDS and TB. A discrete SEIT model with age and infection age structures is formulated to investigate the dynamics of the disease spread. The basic reproduction number R0 is defined and used as the threshold parameter to character- ize the disease extinction or persistence. It is shown that the disease-free equilibrium is globally stable if R0 〈 1, and it is unstable if R0 〉 1. When R0 〉 1, there exists an endemic equilibrium, and the disease is uniformly persistent. The stability of the endemic equilibrium is investigated numerically. 展开更多
关键词 Discrete epidemic model infection age structure basic reproduction number persistence.
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