JPEG 2000编码参数对遥感影像压缩质量的影响

离散小波变换和EBCOT编码是JPEG 2000标准的核心技术,调整其编码参数对图像压缩性能有重要影响。将压缩后影像与原始影像做对比,通过大量实验重点分析小波变换级数和码块大小对不同压缩倍率下重建图像质量的影响,并给出不同压缩比下编码参数的适宜取值范围。实验结果表明,影像进行中、低倍率压缩时,可以设置较低的小波变换级数(2级或3级)和较小的码块大小(如8×8或16×16)对图像进行编码;影像进行较高倍率压缩时,需要设置较高的变换级数(4级或5级)和较大的码块大小(如32×32)使图像获得较高的重建质量。相关结论为影像压缩实际参数的选择提供依据。     

Assessment of nitrogen maintenance requirement in juvenile Black Porgy <Emphasis Type="Italic">Acanthopagrus schlegeli</Emphasis>

Nitrogen balance method and nitrogen-free diet were used in this study to determine nitrogen maintenance requirement (NM) and nitrogen maintenance requirement per unit metabolism body weight (NM′) of black porgy Acanthopagrus schlegeli. Fish with body weight (BW) of 50, 80, 120, 160 and 200 g were fed by the diets containing three graded levels of crude protein (380, 420 and 460 g/kg). The results from nitrogen balance experiment showed that the amount of nitrogen deposition varied from 0.15 to 0.31 mg/g BW per day, accounting for 12.2% to 21.1% of nitrogen intake. The amount of fecal nitrogen excretion varied from 0.21 to 0.32 mg/g BW per day, accounting for 16.3% to 21.6% of nitrogen intake. The endogenous nitrogen excretion, a main part of nitrogen consumption varied from 0.79 to 0.97 mg/g BW per day, accounting for 63.3 % to 68.0% of nitrogen intake. Positive correlation was found between NM and body weight, while a negative correlation was found between NM of unit body weight and the growth duration. No significant differences (p>0.05) were found in NM′ among different growth stages. The average of NM′ was 0.485 7mg/g per day. The results from nitrogen-free diet experiment showed that a negative correlation between NM and feed intake of nitrogen-free diet. NM increased with the decrease of feed intake of fish. The average of NM was 0.482 9 mg/g BW per day that was close to 0.483 8 mg/g BW obtained from fish with 120 g BW in nitrogen balance experiment. The nitrogen balance method is recommended to be a better method for determining NM in consideration of fish stress and result stability. This study also provides a calculated result of the protein content in diets, which is necessary for maintaining fish body protein at different growth stages. The calculation was based on the amount of nitrogen required for maintaining body protein per kg BW. Supported by Scientific Research Project Grant (No.2004C100059) from the city government of Ningbo, China.     

不同景观特征遥感图像融合的最佳分解层数选取分析

IHS和小波变换相结合的融合方法是一种高效的融合算法.影响该算法性能的因素有很多,其中分解层数的选取对融合图像质量有重要影响,故针对不同景观特征影像选取最佳分解层数的问题有待深人探讨.本文以SPOT全色影像和TM多光谱影像,选取信息嫡、平均梯度和相关系数3个质量指标,就不同景观特征影像对小波分解层数的响应问题开展了研究...     

求解物质真实灰度级的数字图像处理算法

本文针对探测包裹中物体互相遮挡问题进行了研究,提出了去除遮挡效应得到真实灰度级的数字图像处理算法,实验结果表明该方法切实可行.     

三率"机理及应用刍议

“三率”是地矿部门依法管矿的手段,也是矿山企业依法办矿、提高生产管理和技术水平的体现。文章从社会主义市场经济条件下地矿行政管理的角度,分析了矿业忽视“三率”管理的原因,论述了用“三率”控制矿产资源利用水平的机理,并从矿管工作实例引证“三率”在矿产资源管理中的经验和教训。     

全球30 m地表覆盖遥感制图的总体技术

以2019年09号超强台风“利奇马”引发的浙江省台州临海市受淹为例,利用浙江省水文站和气象站降水量观测资料对国家级地面-卫星-雷达三源融合实况格点降水数据（CMPAS-5km,CMA Multisource Precipitation Analysis System）进行检验评估;然后,基于CMPAS-5km计算的面雨量和降水分布权重栅格驱动FloodArea二维水动力淹没模型,在“暴雨情景”下进行洪涝模拟,并借助哨兵1号合成孔径雷达卫星（Sentinel-1 SAR）资料和地面验证点开展模拟受淹验证。结果表明：CMPAS-5km降水与站点降水的时空一致性较好,与水文站、“水文站+气象站”两套资料的过程降水量相关系数均达0.89,与水文站逐小时平均降水的相关系数为0.79、均方根误差为1.7 mm·h^-1;在台州受淹模拟区,CMPAS-5km、水文站及气象站三者的小时面雨量变化趋势较为一致,过程累积面雨量分别为305.5 mm、304.1 mm和283.7 mm;CMPAS-5km在数据稳定性、时效性、精细度及数据接口上较其他两套资料有优势;在SAR影像中新增水体明显区域与FloodArea模拟结果匹配较好,模拟水深与4个验证点的实际水深的误差均在±22%以内。

     

Relative sea-level rise and the conterminous United States: Consequences of potential land inundation in terms of population at risk and GDP loss

Global sea-level rise poses a significant threat not only for coastal communities as development continues but also for national economies. This paper presents estimates of how future changes in relative sea-level rise puts coastal populations at risk, as well as affect overall GDP in the conterminous United States. We use four different sea-level rise scenarios for 2010–2100: a low-end scenario (Extended Linear Trend) a second low-end scenario based on a strong mitigative global warming pathway (Global Warming Coupling 2.6), a high-end scenario based on rising radiative forcing (Global Warming Coupling 8.5) and a plausible very high-end scenario, including accelerated ice cap melting (Global Warming Coupling 8.5+). Relative sea-level rise trends for each US state are employed to obtain more reasonable rates for these areas, as long-term rates vary considerably between the US Atlantic, Gulf and Pacific coasts because of the Glacial Isostatic Adjustment, local subsidence and sediment compaction, and other vertical land movement. Using these trends for the four scenarios reveals that the relative sea levels predicted by century's end could range – averaged over all states – from 0.2 to 2.0 m above present levels. The estimates for the amount of land inundated vary from 26,000 to 76,000 km². Upwards of 1.8 to 7.4 million people could be at risk, and GDP could potentially decline by USD 70–289 billion. Unfortunately, there are many uncertainties associated with the impact estimates due to the limitations of the input data, especially the input elevation data. Taking this into account, even the most conservative scenario shows a significant impact for the US, emphasizing the importance of adaptation and mitigation.     

区域旅游地理层次与人造景点之创意策划--回顾陈传康教授地段地理学思想

在简述人造景点之必然与存在问题的前提下,以区域旅游层次学观点论述了人造景点策划的地理环境问题.     

River Discharge and Water Level Changes in the Mekong River: Droughts in an Era of Mega-Dams

While 1992 marked the first major dam – Manwan – on the main stem of the Mekong River, the post-2010 era has seen the construction and operationalisation of mega dams such as Xiaowan (started operations in 2010) and Nuozhadu (started operations in 2014) that were much larger than any dams built before. The scale of these projects implies that their operations will likely have significant ecological and hydrological impacts from the Upper Mekong Basin to the Vietnamese Delta and beyond. Historical water level and water discharge data from 1960 to 2020 were analysed to examine the changes to streamflow conditions across three time periods: 1960–1991 (pre-dam), 1992–2009 (growth) and 2010–2020 (mega-dam). At Chiang Saen, the nearest station to the China border, monthly water discharge in the mega-dam period has increased by up to 98% during the dry season and decreased up as much as −35% during the wet season when compared to pre-dam records. Similarly, monthly water levels also rose by up to +1.16 m during the dry season and dropped by up to −1.55 m during the wet season. This pattern of hydrological alterations is observed further downstream to at least Stung Treng (Cambodia) in our study, showing that Mekong streamflow characteristics have shifted substantially in the post-2010 era. In light of such changes, the 2019–2020 drought – the most severe one in the recent history in the Lower Mekong Basin – was a consequent of constructed dams reducing the amount of water during the wet season. This reduction of water was exacerbated by the decreased monsoon precipitation in 2019. Concurrently, the untimely operationalisation of the newly opened Xayaburi dam in Laos coincided with the peak of the 2019–2020 drought and could have aggravated the dry conditions downstream. Thus, the mega-dam era (post-2010) may signal the start of a new normal of wet-season droughts.