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海底电缆陆检噪音衰减方法及其在乌石地区的应用 被引量:7
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作者 史文英 方中于 +3 位作者 李列 张立霞 张健男 张兴岩 《世界地质》 CAS 2015年第2期516-523,共8页
海底电缆采集方式不同于传统的海洋托缆地震资料采集,检波器放在海底进行地震信号接收,一般是多分量检波器。检波器由于和海底的耦合性不好,一般信噪比较低,接收到的有效信号很弱,而地滚波和转换横波等噪音能量很强;其中转换横波对信号... 海底电缆采集方式不同于传统的海洋托缆地震资料采集,检波器放在海底进行地震信号接收,一般是多分量检波器。检波器由于和海底的耦合性不好,一般信噪比较低,接收到的有效信号很弱,而地滚波和转换横波等噪音能量很强;其中转换横波对信号的干扰较大,也较难衰减。通过对乌石工区海底电缆资料进行统计分析,发现数据在共检波点域转换横波噪音相干性较好,于是在共检波点域使用τ-p变换方法将转换横波从数据中分离出来,分离转换横波后的陆检分量数据信噪比获得了极大的提高。 展开更多
关键词 海底电缆 信噪比 陆检 转换横波
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提高双检检波器陆检信噪比的研究 被引量:1
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作者 韩学义 曹建明 +2 位作者 刘军 陈浩林 张洪军 《物探装备》 2013年第4期226-231,共6页
用双检检波器接收是目前海底电缆勘探的主流方法,但双检检波器中的陆检接收效果一直处于较差的状态,其表现形式为信噪比偏低,抗干扰能力较差,严重影响了生产时效和后期资料的处理。本文从仪器原理的角度出发,通过对检波器与海底的耦合... 用双检检波器接收是目前海底电缆勘探的主流方法,但双检检波器中的陆检接收效果一直处于较差的状态,其表现形式为信噪比偏低,抗干扰能力较差,严重影响了生产时效和后期资料的处理。本文从仪器原理的角度出发,通过对检波器与海底的耦合以及在有限的空间内对动圈检波器进行有效组合的研究,提高了陆检的信噪比和抗干扰能力,进一步提高了双检检波器的采集效果。 展开更多
关键词 双检检波器 陆检 组合 耦合 信噪比
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海底电缆双检资料陆检微分合并技术 被引量:6
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作者 秦宁 《地球物理学进展》 CSCD 北大核心 2018年第3期1269-1273,共5页
海底电缆(OBC)技术是滩浅海地震勘探的重要手段,其采集特点是将炮点沉放在水下一定深度,而检波器铺设在海底,这就使得地震波在海水层中震荡产生鸣震,因此水陆双检采集方式应运而生.在OBC双检数据的资料处理中,如何实现水检和陆检的一致... 海底电缆(OBC)技术是滩浅海地震勘探的重要手段,其采集特点是将炮点沉放在水下一定深度,而检波器铺设在海底,这就使得地震波在海水层中震荡产生鸣震,因此水陆双检采集方式应运而生.在OBC双检数据的资料处理中,如何实现水检和陆检的一致性融合是关键,其目的是利用水检和陆检对有效波和鸣震的不同响应来压制鸣震干扰.常用的合并方式基于水检和陆检波场相同的假设,将两者进行能量匹配后直接合并,造成有效波受到损害,鸣震压制效果差.本文提出一种陆检微分合并新技术,将陆检资料进行微分处理后,根据其与水检资料的能量关系确定尺度变换因子,然后将陆检微分结果与水检进行合并.模型测试以及实际资料应用效果验证了陆检微分合并技术能够在保护有效波的前提下,消除鸣震干扰,拓宽频带,提高分辨率. 展开更多
关键词 海底电缆 双检合并 水检 陆检 陆检微分
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渤海多工区交叠区域潜山成像精细处理技术研究与应用
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作者 席自彬 《海洋工程装备与技术》 2023年第4期130-134,共5页
目前,渤海工区已实现三维采集全覆盖,但不同工区施工时间跨度较大,存在多种采集方式。不同工区在采集方向、偏移距范围、振幅大小、频率特征、信噪比等方面存在较大差异,给多工区交叠区域潜山成像带来艰巨挑战。针对渤海多工区交叠区域... 目前,渤海工区已实现三维采集全覆盖,但不同工区施工时间跨度较大,存在多种采集方式。不同工区在采集方向、偏移距范围、振幅大小、频率特征、信噪比等方面存在较大差异,给多工区交叠区域潜山成像带来艰巨挑战。针对渤海多工区交叠区域老资料重处理问题,本文从精细关键处理技术、精细拼接技术、高精度三维叠前深度偏移3个方向着手和重点攻关,以提高潜山构造区成像质量。通过实际资料验证,本文处理方法对渤海多工区交叠区域老资料潜山成像效果提升显著,较好地验证了本文方法的有效性。 展开更多
关键词 潜山成像 陆检横波泄露噪音衰减 全信息校正水陆检合并 精细拼接技术 高斯射线束叠前深度偏移
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Using 4C OBS to reveal the distribution and velocity attributes of gas hydrates at the northern continental slope of South China Sea 被引量:7
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作者 沙志彬 张明 +2 位作者 张光学 梁金强 苏丕波 《Applied Geophysics》 SCIE CSCD 2015年第4期555-563,628,629,共11页
To investigate the distribution and velocity attributes of gas hydrates in the northern continental slope of South China Sea, Guangzhou Marine Geological Survey conducted four-component (4C) ocean-bottom seismometer... To investigate the distribution and velocity attributes of gas hydrates in the northern continental slope of South China Sea, Guangzhou Marine Geological Survey conducted four-component (4C) ocean-bottom seismometer (OBS) surveys. A case study is presented to show the results of acquiring and processing OBS data for detecting gas hydrates. Key processing steps such as repositioning, reorientation, PZ summation, and mirror imaging are discussed. Repositioning and reorientation find the correct location and direction of nodes. PZ summation matches P- and Z-components and sums them to separate upgoing and downgoing waves. Upgoing waves are used in conventional imaging, whereas downgoing waves are used in mirror imaging. Mirror imaging uses the energy of the receiver ghost reflection to improve the illumination of shallow structures, where gas hydrates and the associated bottom-simulating reflections (BSRs) are located. We developed a new method of velocity analysis using mirror imaging. The proposed method is based on velocity scanning and iterative prestack time migration. The final imaging results are promising. When combined with the derived velocity field, we can characterize the BSR and shallow structures; hence, we conclude that using 4C OBS can reveal the distribution and velocity attributes of gas hydrates. 展开更多
关键词 gas hydrates velocity attributes ocean-bottom seismometer PZ summation mirror imaging
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Geophone-seabed coupling effect and its correction 被引量:2
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作者 张保庆 周辉 +1 位作者 李国发 郭建卿 《Applied Geophysics》 SCIE CSCD 2016年第1期145-155,221,共12页
By summing geophone and hydrophone data with opposite polarity responses to water layer reverberation,the ocean bottom cable dual-sensor acquisition technique can effectively eliminate reverberation,broaden the freque... By summing geophone and hydrophone data with opposite polarity responses to water layer reverberation,the ocean bottom cable dual-sensor acquisition technique can effectively eliminate reverberation,broaden the frequency bandwidth,and improve both the resolution and fidelity of the seismic data.It is thus widely used in industry.However,it is difficult to ensure good coupling of the geophones with the seabed because of the impact of ocean flow,seafloor topography,and field operations;therefore,geophone data are seriously affected by the transfer function of the geophone-seabed coupling system.As a result,geophone data frequently have low signal-to-noise ratios(S/N),which causes large differences in amplitude,frequency,and phases between geophone and hydrophone data that severely affect dual-sensor summation.In contrast,the hydrophone detects changes in brine pressure and has no coupling issues with the seabed;thus,hydrophone data always have good S/N.First,in this paper,the mathematical expression of the transfer function between geophone and seabed is presented.Second,the transfer function of the geophone-seabed is estimated using hydrophone data as reference traces,and finally,the coupling correction based on the estimated transfer function is implemented.Using this processing,the amplitude and phase differences between geophone and hydrophone data are removed,and the S/N of the geophone data are improved.Synthetic and real data examples then show that our method is feasible and practical. 展开更多
关键词 OBC Dual-sensor Transfer function of geophone-seabed coupling system Coupling correction
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海上地震双检资料合并处理方法的应用 被引量:9
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作者 苏燕 《物探与化探》 CAS CSCD 2014年第4期754-757,786,共5页
主要对海底电缆双检资料的特点进行了分析研究,针对双检资料的特点,对水陆检近偏移距共检波点叠加剖面进行相关处理,求取海底反射系数和校准算子,进而进行水陆检资料的合并,该方法可以有效地压制海底鸣震,同时也很好的补偿了水检资料的... 主要对海底电缆双检资料的特点进行了分析研究,针对双检资料的特点,对水陆检近偏移距共检波点叠加剖面进行相关处理,求取海底反射系数和校准算子,进而进行水陆检资料的合并,该方法可以有效地压制海底鸣震,同时也很好的补偿了水检资料的频率缺失。利用该方法对某浅海地区的实际资料进行处理,取得了良好的应用效果。 展开更多
关键词 海底电缆 海底鸣震 水检 陆检 多次波 海底反射系数
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海底电缆资料双检合并处理技术研究与应用 被引量:6
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作者 徐强 《工程地球物理学报》 2017年第2期130-134,共5页
海底电缆采集资料通常利用水检和陆检的合并处理来压制电缆鬼波。但通常情况下,鬼波在海底反射形成的海底微屈多次波对资料的影响也很严重。分析了水检与陆检的地震波接收的物理机制,在水陆合并压制鬼波后,通过求取海底反射系数,进一步... 海底电缆采集资料通常利用水检和陆检的合并处理来压制电缆鬼波。但通常情况下,鬼波在海底反射形成的海底微屈多次波对资料的影响也很严重。分析了水检与陆检的地震波接收的物理机制,在水陆合并压制鬼波后,通过求取海底反射系数,进一步利用双检数据来压制海底微屈多次波。经实际数据的应用表明,这种方法可以较好地同时压制电缆鬼波和海底微屈多次波,改善剖面的波组特征。 展开更多
关键词 海底电缆 水检 陆检 鬼波 微屈多次波
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海底电缆在三维作业中的现场质量控制
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作者 由志刚 《物探装备》 1999年第1X期32-34,53,共4页
本文阐述了现场质量控制系统的配置、野外施工要求及Focus的特性,并结合野外实际作业,总结出了三维(3D)现场处理的工作方法和工作流程。
关键词 电缆 质量控制 水检 陆检
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对双检检波器反序故障的分析与探讨 被引量:1
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作者 李猛 韩学义 +1 位作者 曹建明 王道杰 《物探装备》 2013年第5期300-302,共3页
双检检波器是OBC(海底电缆)上配套用的一种地震勘探传感器,它将高灵敏度的磁电检波器和海洋压电检波器合二为一,即把陆检检波器和水检检波器两种接收装置结合在一起。此双检检波器大大提高了地震采集资料的优良品率,并能够较好地压制虚... 双检检波器是OBC(海底电缆)上配套用的一种地震勘探传感器,它将高灵敏度的磁电检波器和海洋压电检波器合二为一,即把陆检检波器和水检检波器两种接收装置结合在一起。此双检检波器大大提高了地震采集资料的优良品率,并能够较好地压制虚反射和海水鸣振。但是408ULS的双检采集系统经常会出现反序的现象,本文通过对双检检波器反序故障的分析,找出了应对双检检波器反序故障的实际方法。 展开更多
关键词 双检检波器 反序 陆检 水检
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Checking of seismic and tsunami hazard for coastal NPP of Chinese continent after Fukushima nuclear accident
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作者 Chang Xiangdong Zhou Bengang Zhao Lianda 《Engineering Sciences》 EI 2013年第3期60-65,共6页
A checking on seismic and tsunami hazard for coastal nuclear power plant (NPP) of Chinese continent has been made after Japanese Fukushima nuclear accident caused by earthquake tsunami. The results of the checking are... A checking on seismic and tsunami hazard for coastal nuclear power plant (NPP) of Chinese continent has been made after Japanese Fukushima nuclear accident caused by earthquake tsunami. The results of the checking are introduced briefly in this paper,including the evaluations of seismic and tsunami hazard in NPP siting period,checking results on seismic and tsunami hazard. Because Chinese coastal area belongs to the continental shelf and far from the boundary of plate collision,the tsunami hazard is not significant for coastal area of Chinese continent. However,the effect from tsunami still can't be excluded absolutely since calculated result of Manila trench tsunami source although the tsunami wave is lower than water level from storm surge. The research about earthquake tsunami will continue in future. The tsunami warning system and emergency program of NPP will be established based on principle of defense in depth in China. 展开更多
关键词 NPP seismic hazard tsunami hazard subduction zone fukushima nuclear accident
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Anomaly Detection in MODIS Land Products via Time Series Analysis 被引量:1
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作者 ZHANG Jingxiong David Roy +1 位作者 Sadashiva Devadiga ZHENG Min 《Geo-Spatial Information Science》 2007年第1期44-50,共7页
With remote sensing information products becoming increasingly varied and arguably improved, scientific applications of such products rely on their quality assessment. In an operational context such as the NASA (Natio... With remote sensing information products becoming increasingly varied and arguably improved, scientific applications of such products rely on their quality assessment. In an operational context such as the NASA (National Aeronautics and Space Administration) information production based on the MODIS (Moderate Resolution Imaging Spectroradiometer) instrument on board Earth Observing System (EOS) Terra and Aqua satellites, efficient ways of detecting product anomaly, i.e., to discriminate between product artifacts and real changes in Earth processes being monitored, are extremely important to assist and inform the user communities about potential unreliability in the products. A technique for anomaly detection, known as MAD (the median of absolute deviate from the median), in MODIS land products via time series analysis is described, which can handle intra- and in-ter-annual variation in the data by using MAD statistics of the original data and their first-order difference. This method is shown to be robust and work across major land products, including NDVI, active fire, snow cover, and surface reflectance, and its applicabil-ity to multi-disciplinary products is anticipated. 展开更多
关键词 anomaly detection MODIS land products time series
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Retrieval of Land-surface Temperature from AMSR2 Data Using a Deep Dynamic Learning Neural Network 被引量:3
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作者 MAO Kebiao ZUO Zhiyuan +3 位作者 SHEN Xinyi XU Tongren GAO Chunyu LIU Guang 《Chinese Geographical Science》 SCIE CSCD 2018年第1期1-11,共11页
It is more difficult to retrieve land surface temperature(LST) from passive microwave remote sensing data than from thermal remote sensing data, because the emissivities in the passive microwave band can change more e... It is more difficult to retrieve land surface temperature(LST) from passive microwave remote sensing data than from thermal remote sensing data, because the emissivities in the passive microwave band can change more easily than those in the thermal infrared band. Thus, it is very difficult to build a stable relationship. Passive microwave band emissivities are greatly influenced by the soil moisture, which varies with time. This makes it difficult to develop a general physical algorithm. This paper proposes a method to utilize multiple-satellite, sensors and resolution coupled with a deep dynamic learning neural network to retrieve the land surface temperature from images acquired by the Advanced Microwave Scanning Radiometer 2(AMSR2), a sensor that is similar to the Advanced Microwave Scanning Radiometer Earth Observing System(AMSR-E). The AMSR-E and MODIS sensors are located aboard the Aqua satellite. The MODIS LST product is used as the ground truth data to overcome the difficulties in obtaining large scale land surface temperature data. The mean and standard deviation of the retrieval error are approximately 1.4° and 1.9° when five frequencies(ten channels, 10.7, 18.7, 23.8, 36.5, 89 V/H GHz) are used. This method can effectively eliminate the influences of the soil moisture, roughness, atmosphere and various other factors. An analysis of the application of this method to the retrieval of land surface temperature from AMSR2 data indicates that the method is feasible. The accuracy is approximately 1.8° through a comparison between the retrieval results with ground measurement data from meteorological stations. 展开更多
关键词 RADIOMETRY Advanced Microwave Scanning Radiometer 2 (AMSR2) passive remote sensing inverse problem
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Livelihood Factors and Household Strategies for an Unexpected Climate Event in Upland Northern Laos 被引量:1
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作者 Phanxay INGXAY Satoshi YOKOYAMA Isao HIROTA 《Journal of Mountain Science》 SCIE CSCD 2015年第2期483-500,共18页
Climate events pose major challenges to food production and the livelihoods of rural inhabitants in northern Laos, where upland rice using swidden production is an important crop. The onset of the rainy season in this... Climate events pose major challenges to food production and the livelihoods of rural inhabitants in northern Laos, where upland rice using swidden production is an important crop. The onset of the rainy season in this area is one such climate event, and it has occurred earlier and with less regularity in recent years. Not all households are able to cope with these changes. This study examines the ability of local farmers to cope with rice insufficiency. This investigation also clarifies household strategies in dealing with the climate event. We randomly interviewed 63 of 95 household heads, and performed a paired sample t test to examine the significance of differences in three household groups between the 2010 normal climate and the 2011 climate event. The groups were categorized according to rice selfsufficiency in 2011: groups I are households with rice self-sufficiency, group II are those facing a rice shortage of up to 3 months, and group III are those with insufficient rice for over 3 months. We also conducted a one-way ANOVA to examine the significance of differences in livelihood strategies among the three groups. We found that the household labor force was the most important factor in enhancing the villagers' ability to deal with the climate event and that the level of impact of that event shaped their coping strategies. Households with substantial labor force had more options for coping strategies than those with smaller ones. The villagers faced different levels of impact and adopted differentcoping strategies accordingly. Non-timber forest product collection was the principle livelihood strategy in response to non-climate factors such as education, access to health services, provision of equipment and clothing, and overcoming the impact of the climate event. Households heavily affected by the early rainy season onset tended to engage in intensive activities such as off-farm activity and outside work, rather than their major livelihood activities in the village(upland crop and livestock production). 展开更多
关键词 Climate events Livelihood factors Livelihood change Household strategy Swidden
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A comparison of atmospheric CO_2 concentration GOSAT-based observations and model simulations 被引量:6
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作者 LEI LiPing GUAN XianHua +3 位作者 ZENG ZhaoCheng ZHANG Bing RU Fei BU Ran 《Science China Earth Sciences》 SCIE EI CAS 2014年第6期1393-1402,共10页
Satellite observations of atmospheric CO2 are able to truly capture the variation of global and regional CO2 concentration.The model simulations based on atmospheric transport models can also assess variations of atmo... Satellite observations of atmospheric CO2 are able to truly capture the variation of global and regional CO2 concentration.The model simulations based on atmospheric transport models can also assess variations of atmospheric CO2 concentrations in a continuous space and time,which is one of approaches for qualitatively and quantitatively studying the atmospheric transport mechanism and spatio-temporal variation of atmospheric CO2 in a global scale.Satellite observations and model simulations of CO2 offer us two different approaches to understand the atmospheric CO2.However,the difference between them has not been comprehensively compared and assessed for revealing the global and regional features of atmospheric CO2.In this study,we compared and assessed the spatio-temporal variation of atmospheric CO2 using two datasets of the column-averaged dry air mole fractions of atmospheric CO2(XCO2)in a year from June 2009 to May 2010,respectively from GOSAT retrievals(V02.xx)and from Goddard Earth Observing System-Chemistry(GEOS-Chem),which is a global 3-D chemistry transport model.In addition to the global comparison,we further compared and analyzed the difference of CO2 between the China land region and the United States(US)land region from two datasets,and demonstrated the reasonability and uncertainty of satellite observations and model simulations.The results show that the XCO2 retrieved from GOSAT is globally lower than GEOS-Chem model simulation by 2 ppm on average,which is close to the validation conclusion for GOSAT by ground measures.This difference of XCO2 between the two datasets,however,changes with the different regions.In China land region,the difference is large,from 0.6 to 5.6 ppm,whereas it is 1.6 to 3.7 ppm in the global land region and 1.4 to 2.7 ppm in the US land region.The goodness of fit test between the two datasets is 0.81 in the US land region,which is higher than that in the global land region(0.67)and China land region(0.68).The analysis results further indicate that the inconsistency of CO2concentration between satellite observations and model simulations in China is larger than that in the US and the globe.This inconsistency is related to the GOSAT retrieval error of CO2 caused by the interference among input parameters of satellite retrieval algorithm,and the uncertainty of driving parameters in GEOS-Chem model. 展开更多
关键词 GOSAT GEOS-CHEM atmospheric CO2 concentration INCONSISTENCY regional comparison
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Examining urban land-cover characteristics and ecological regulation during the construction of Xiong'an New District, Hebei Province, China 被引量:6
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作者 匡文慧 杨天荣 颜凤芹 《Journal of Geographical Sciences》 SCIE CSCD 2018年第1期109-123,共15页
Development of Xiong'an New District(XND) is integral to the implementation of the Beijing-Tianjin-Hebei(BTH) Integration Initiative. It is intended to ease the non-capital functions of Beijing, optimize regional ... Development of Xiong'an New District(XND) is integral to the implementation of the Beijing-Tianjin-Hebei(BTH) Integration Initiative. It is intended to ease the non-capital functions of Beijing, optimize regional spatial patterns, and enhance ecosystem services and living environment in this urban agglomeration. Applying multi-stage remote sensing(RS) images, land use/cover change(LUCC) data, ecosystem services assessment data, and high-precision urban land-cover information, we reveal the regional land-cover characteristics of this new district as well as across the planned area of the entire BTH urban agglomeration. Corresponding ecological protection and management strategies are also proposed. Results indicated that built-up areas were rapidly expanding, leading to a continuous impervious surface at high density. Urban and impervious surface areas(ISAs) grew at rates 1.27 and 1.43 times higher than that in the 2000 s, respectively, seriously affecting about 15% area of the sub-basins. Construction of XND mainly encompasses Xiongxian, Rongcheng, and Anxin counties, areas which predominantly comprise farmland, townships and rural settlements, water, and wetland ecosystems. The development and construction of XND should ease the non-capital functions of Beijing, as well as moderately control population and industrial growth. Thus, this development should be included within the national ‘sponge city' construction pilot area in early planning stages, and reference should be made to international low-impact development modes in order to strengthen urban green infrastructural construction. Early stage planning based on the existing characteristics of the underlying surface should consider the construction of green ecological patches and ecological corridors between XND and the cities of Baoding, Beijing, and Tianjin. The proportion of impervious surfaces should not exceed 60%, while that of the core area should not exceed 70%. The development of XND needs to initiate the concept of ‘planning a city according to water resource amount' and incorporate rainwater collection and recycling. 展开更多
关键词 Xiong'an New District urban land use urban impervious surface Beijing-Tianjin-Hebei urban ag-glomeration ecological protection strategies
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Detecting and mapping annual newly-burned plots(NBP) of swiddening using historical Landsat data in Montane Mainland Southeast Asia(MMSEA) during 1988–2016 被引量:5
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作者 李鹏 封志明 +2 位作者 肖池伟 BOUDMYXAY Khampheng 刘宇 《Journal of Geographical Sciences》 SCIE CSCD 2018年第9期1307-1328,共22页
Swidden agriculture is by far the dominant land use system in the uplands of Southeast Asia (SEA), as well as other tropical regions, which plays an important role in the implementation of Reducing Emissions from De... Swidden agriculture is by far the dominant land use system in the uplands of Southeast Asia (SEA), as well as other tropical regions, which plays an important role in the implementation of Reducing Emissions from Deforestation and Forest Degradation (REDD) of United Nations. To our knowledge, the long-term inter-annual area of newly burned plots (NBP) of swidden agriculture in mainland Southeast Asia is still not available, let alone in the whole tropics. With the strengthening regional geo-economic cooperation in SEA, swidden agriculture has experienced and/or is still experiencing extensive and drastic transformations into other diverse market-oriented land use types since the 1990s. In this study, high-level surface reflectance products of Landsat 4151718 family sensors including Thematic Mapper (TM), Enhanced Thematic Mapper Plus (ETM+) and Operational Land Imager (OLI) acquired in March, April and May of each year between 1988 and 2016 were firstly utilized to detect and monitor the extent and area of NBP of swidden agriculture with multiple thresholds of four commonly-used vegetation indices, namely the Normalized Difference Vegetation Index (NDVI), Normalized Difference Moisture Index (NDMI), Normalized Burn Ratio (NBR) and Soil Adjusted Vegetation Index (SAVI), in combination with local phenological features of swid- dening and topographical data. The results showed that: (1) an annual average of 6.08×104 km2 of NBP of swidden agriculture, or 3.15% of the total land area of MSEA, were estimated in the past nearly three decades. (2) Annual NBP were primarily distributed in four major geomorphic units including the Central Range of Hills, Northern Mountainous Region, West- ern Myanmar Hills, and Annamite Chain. (3) A decadal average analysis indicated that the NBP of swidden agriculture opened year by year declined as a whole, especially after 2010, merely with an average of 5.23×104 km2. (4) The top ten provincial administrative units in Cambodia, Laos, Myanmar, Thailand and Vietnam, which consistently accounted for over 90% of the newly opened swiddens of each country, showed distinct fluctuations in usingslash-and-burn practices in the last decades. The Landsat-based (30 m) reconstructed 29-year longitudinal updated maps (including extent and area) of the NBP of swidden agri- culture may contribute to REDD and local livelihood related studies in Continental Southeast Asia. Our study further demonstrated that the multiple vegetative indices thresholds approach holds great potential in detecting swidden agriculture in tropical mountainous regions. 展开更多
关键词 swidden agriculture phenology newly-burned plots (NBP) LANDSAT Montane Mainland SoutheastAsia (MMSEA)
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Wild dogma: An examination of recent "evidence" for dingo regulation of invasive mesopredator release in Australia 被引量:3
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作者 Benjamin L. ALLEN Richard M. ENGEMAN Lee R. ALLEN 《Current Zoology》 SCIE CAS CSCD 北大核心 2011年第5期568-583,共16页
There is growing interest in the role that apex predators play in shaping terrestrial ecosystems and maintaining tro- phic cascades. In line with the mesopredator release hypothesis, Australian dingoes (Canis lupus d... There is growing interest in the role that apex predators play in shaping terrestrial ecosystems and maintaining tro- phic cascades. In line with the mesopredator release hypothesis, Australian dingoes (Canis lupus dingo and hybrids) are assumed by many to regulate the abundance of invasive mesopredators, such as red foxes Vulpes vulpes and feral cats Fells catus, thereby providing indirect benefits to various threatened vertebrates. Several recent papers have claimed to provide evidence for the bio- diversity benefits of dingoes in this way. Nevertheless, in this paper we highlight several critical weaknesses in the methodologi- cal approaches used in many of these reports, including lack of consideration for seasonal and habitat differences in activity, the complication of simple track-based indices by incorporating difficult-to-meet assumptions, and a reduction in sensitivity for as-sessing populations by using binary measures rather than potentially continuous measures. Of the 20 studies reviewed, 15 of them (75%) contained serious methodological flaws, which may partly explain the inconclusive nature of the literature investigating interactions between invasive Australian predators. We therefore assert that most of the "growing body of evidence" for meso- predator release is merely an inconclusive growing body of literature only. We encourage those interested in studying the eco- logical roles of dingoes relative to invasive mesopredators and native prey species to account for the factors we identify, and cau- tion the value of studies that have not done so [Current Zoology 57 (5): 568-583, 2011]. 展开更多
关键词 Activity index Apex predator Canis lupus dingo Experimental design Mesopredator release Sampling
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MODELING STRATEGIES FOR CONTROLLING H1N1 OUTBREAKS IN CHINA
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作者 JIN ZHANG YANNI XIAO 《International Journal of Biomathematics》 2012年第4期63-81,共19页
There has been a global attack of A/H1N1 virus in 2009, which widely affected the world's normal stability and economic development. Since the emergence of the first diagnosed A/H1N1 influenza infected person in 11 M... There has been a global attack of A/H1N1 virus in 2009, which widely affected the world's normal stability and economic development. Since the emergence of the first diagnosed A/H1N1 influenza infected person in 11 May 2009 in China, very strict policy including quarantine and isolation measures were widely implemented to control the spread of this disease before the vaccine appeared. We propose a compartmental model that mimics the infection process of A/H1N1 under control strategies taken in China's Mainland. Apart from theoretical analysis, using the statistic data of Shaanxi Province, we estimated the unknown epidemiological parameters of this disease in Shaanxi via least-squares fitting method. The estimated control reproductive number of H1N1 for its first peak was Rc1 = 2.555 (95% CI: 2.362 2.748) and that for the second peak was Rc2 = 1.886 (95% CI: 1.765-2.001). Our findings in this paper suggest that neither quarantine nor isolation measures could be relaxed, and the implementation of these interventions can reduce the pandemic outbreak of A/H1N1 pandemic significantly. 展开更多
关键词 A/HIN1 influenza QUARANTINE ISOLATION least-squares fitting.
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