基于模糊熵的GLLE熵阈值分割方法

图像分割是计算机视觉中基础且重要的一个问题.熵阈值图像分割作为一种有效的分割方法,被广泛应用于模式识别和图像处理中.传统的图像分割方法并不能获得足够有效的图像特征.为解决这个问题且进一步探究熵阈值在图像分割中的应用,引入一种GLLE（Gray Level and Local Entropy）二维直方图改进熵阈值图像分割模型,并提出了基于模糊熵的方法计算所建立的二维直方图模型.通过标准实验数据集上的对比实验表明,基于模糊熵的GLLE熵阈值分割方法可以得到更加准确的阈值,提高了分割精度.同时在处理不同类型图像的表现上优于往常的算法,具有更强的鲁棒性.     

基于形态学灰度重构的乳腺微钙化点提取

针对乳腺X线摄片,提出了一种计算机辅助检测乳腺微钙化点的方法:首先利用灰度形态重构完成穹顶提取,除去乳腺背景结构同时又能很好地保留微钙化点;其次运用拉普拉斯算子在空间域内对图像进行锐化以增强微钙化点;然后在频率域内利用巴特沃思高通滤波器对图像进行高通滤波;最后利用二维最大熵阈值分割对图像二值化,从而检测出微钙化点并在图像上标识出来。计算机辅助诊断的方法不仅避免了医生因大量阅片引起疲劳而造成误诊,起到了协助医生诊断的作用,而且提高了诊断的效率和准确率。     

EXPERIMENTAL INVESTIGATION AND ANALYSIS OF HEC-6 RIVER MORPHOLOGICAL MODEL

Only comparatively few experimental studies have been carried out to investigate the performance of the HEC-6 river morphological model. The model was developed by the Hydrologic Engineering Center of the US Army Corps of Engineers. In this study, experiments were carried out in a 20 m long concrete flume 0.6 m wide with varying rectangular cross-sections. The channel bed is paved with uniform sand of D₅₀ = 0.9 mm and D₉₀ = 1.2 mm within the test reach of 12 m. Two types of experiments were carried out with sediment transport, one under steady uniform flow and another under steady non-uniform flow conditions. Nine steady uniform flow experiments were carried out to compare the measured equilibrium relationship of flow and sediment transport rate with two bedload formulae, namely, Du Boys and Meyer–Peter and Muller, and with three total load formulae, namely, Toffaleti, Laursen and Yang. It was found that even though the sediment transport consists of a certain portion of bedload, the total load formulae give satisfactory results and better agreement than the two bedload formulae. Five steady non-uniform flow experiments were carried out under various conditions of varying bed profile and channel width and also with sediment addition and withdrawal. The measured transient water surface and bed profiles are compared with the computed results from the HEC-6 model. It was found that the Toffaleti and Yang total load formulae used in the HEC-6 model give the most satisfactory prediction of actual bed profiles under various conditions of non-uniform flow and sediment transport. The effects of Manning's n, variations of sediment inflow, various sediment transport formulae, sediment grain size and the model numerical parameters, i.e. distance interval Δx and numerical weighting factor, on the computed water surface and bed profiles were determined. It was found that the selection of the sediment transport formulae has the most significant effect on the computed results. It can be concluded that the HEC-6 model can predict satisfactorily a long-term average pattern of local scour and deposition along a channel with either a small abrupt change in geometry or gradually varying cross-sections. However, the accuracy of the model prediction is reduced in the regions where highly non-uniform flow occurs.     

城市化对南京地区土壤多样性影响的灰色关联分析

随着城市化的发展,越来越多的土壤资源被侵占。本文借助RS和GIS技术,根据1984年、1995年、2003年3期TM遥感影像 (30m×30m),采用多时相连续对比法对南京地区近20年来城镇扩张情况进行了分析;结合南京地区土壤图,利用生态学领域中的多样性测度方法计算了城市化背景下南京地区的土壤多样性指数 (HP)、土壤均匀度指数 (Jsw) 和土壤丰富度指数 (R₂),进而在镇级尺度上对1984~2003年南京地区土壤多样性时空变化特点进行了研究;利用灰色系统理论中的灰色关联分析方法,对南京地区各级行政区划单位的扩张对土壤多样性的影响进行了初步探讨。分析结果表明,各级行政区划中村庄的扩张对土壤多样性指数的影响最广,约占研究区总面积的60%;镇、县和市的扩张对土壤多样性的影响逐渐减少,各占研究区总面积的26%、7%和7%。     

基于DEM数据的巴丹吉林沙漠沙丘分布规律及其形态参数

沙丘形态特征是风沙地貌研究的重要内容。数字高程模型（DEM）因卓越的三维地形表达能力被广泛应用于沙丘形态研究中。长期以来,受交通条件和研究方法的制约以及高大沙山分布位置的限定,对巴丹吉林沙漠沙丘形态的研究主要集中在沙漠东南部,缺乏对整个沙漠沙丘分布规律及其形态参数特征的系统认知。而对整个沙漠沙丘形态特征的研究,是区域风沙地貌形成与演化研究的重要组成部分。以巴丹吉林沙漠内所有独立沙丘为研究对象,利用研究区DEM数据和一种新的算法,研究了沙漠内两种主要类型沙丘（横向沙丘、星状沙丘）的分布规律及其形态参数特征。结果表明：沙漠内独立沙丘大约有6 033座,高度9~433 m,高度超过350 m的巨型沙山共有53座,其中星状沙山7座,最大高度383 m;横向沙山46座,最大高度433 m。横向沙丘高度与等效沙丘厚度呈正相关的线性函数关系,星状沙丘高度与等效沙丘厚度呈正相关的对数函数关系,表明在现代气候和环境条件下,横向沙丘高度仍在增加,而星状沙丘高度增长已经趋缓。两类沙丘的主轴向大都垂直于研究区主风向NW-SE。横向沙丘起沙风风向单一,沙丘轴向集中在NE-SW和NNE-SSW方向;星状沙丘起沙风风向略为复杂,沙丘存在多个次级轴向。     

长江口扁担沙动力地貌变化过程研究

河口浅滩不仅为人类提供宝贵湿地资源,而且是调控河势演变的重要因素。研究河口浅滩动力地貌演变规律对航道整治、湿地生态开发及岸堤防护等具有重要价值。本文利用最近150多年的长江口历史海图资料、实测水深与水文泥沙数据,分析长江口南支最大的浅滩—扁担沙动力地貌演变格局及其变化机制。结果表明:(1) 1860?2016年期间,扁担沙反复历经淤积?冲刷?淤积,浅滩由最初水下阴滩发育出露而形成纺锤状沙体,随后演变为细长扁担状,沙尾切滩成爪状沙体,下扁担沙则伴随爪状缝隙被不断填充而淤长;(2)自1954年洪水到目前,扁担沙?2 m、?5 m等深线包络的面积与体积整体上均呈现增长态势,其中面积年均增长率分别为0.88 km2/a和0.81 km2/a,体积年均增长率分别为1.3×106 m3/a和5×106 m3/a;扁担沙浅滩在不同时期冲淤变化不同,其中1998年出现大幅度冲刷,平均冲刷厚度达到1.4 m;(3)扁担沙体积变化和长江入海泥沙的增减无直接联系,但与入海径流量的变化密切相关;(4)白茆沙“南强北弱”的河势、南北港分流工程以及东风西沙水库的建立导致扁担沙向北推移。     

Morphological and molecular evidence supports the first occurrence of two fishes,Siganus sutor(Valenciennes, 1835)and Seriolina nigrofasciata(Rüppell, 1829)(Actinopterygii:Perciformes), from marine waters of Odisha coast,Bay of Bengal,India

Marine ecosystems provide a wide variety of diverse habitats that frequently promote migration and ecological adaptation. The extent to which the geographic distribution of marine organism has reshaped by human activities remains underappreciated. The limitations intrinsic to morphology-based identification systems have engendered an urgent need for reliable genetic methods that enable the unequivocal recognition of fish species,particularly those that are prone to overexploitation and/or market substitution. In the present study, however, an attempt has been taken to identify two locally adapted fish species, Siganus sutor(Valenciennes, 1835) and Seriolina nigrofasciata(Rüppell, 1829) of order Perciformes, which happens to be the first record in Odisha coast,Bay of Bengal. The diagnostic characteristics of Siganus sutor are: dorsal fin XIII-10, anal fin VII-9, pectoral fin 15,pelvic fin II-3, while that of Seriolina nigrofasciata dorsal fin VI-I-35, anal fin I-17, pectoral fin 16, pelvic fin 5. All COI barcodes generated in this study were matched with reference sequences of expected species, according to morphological identification. Bayesian and likelihood phylogenetic trees were drawn based on DNA barcodes and all the specimens clustered in agreement with their taxonomic classification at the species level. The phylogeographic studies based on haplotype network and migration rates suggest that both the species were not panmitic and the high-frequency population distribution indicates successful migration. The result of this study provides an important validation of the use of DNA barcode sequences for monitoring species diversity and changes within a complex marine ecosystem.     

未来我国气体能源发展动向研究

"十四五"期间我国能源需求增速将有所放缓,但仍将处于高位,随着经济社会的不断恢复以及环境问题的显现,未来能源安全形势仍然严峻,及早建立清洁、高效、安全、多元化的现代能源体系,调整优化我国能源供给结构迫在眉睫.本文通过判断我国气体能源发展现状,构建气体能源优先发展评价指标体系,运用层次分析法与灰色关联度评价法对各气体能源...     

Relationships between body weight and other morphological traits in young sea cucumbers Apostichopus japonicas

Correlation, multiple regression, and path analyses were used to investigate the relationships between body weight and three other morphological traits in juvenile Japanese sea cucumbers Apostichopus japonicus . We measured live body weight (BW), body length (BL), numbers of papillae (NP), and numbers of tube feet (NF) at 60, 80, 100, and 130 days post-hatching (dph). We calculated path correlation coefficients, correlation indices ( R 2 ), and coefficients of determination with BW as the dependent variable and the other morphological traits as independent variables. The coefficient of variation for BW was high across all age groups, and all measured morphological traits were significantly correlated ( P < 0.01). BL had the greatest direct eff ect on BW across all age groups (60 dph, 0.526;80 dph, 0.404;100 dph, 0.620;and 130 dph, 0.681), while NF had the greatest indirect eff ect on BW across all age groups (60 dph, 0.528;80 dph, 0.452;100 dph, 0.666;and 130 dph, 0.603). Regression analyses between morphological traits and BW indicated that R 2 was greater than 0.85 only in the 100-dph specimens. The indirect eff ects of the other measured morphological traits on BW were age-dependent. The optimal regression equations, as determined with stepwise regression, were, for 60-dph specimens: BW 60 =10 (-3.04+0.092BL+0.014NP+0.014NF)( R 2 =0.632);for 80-dph specimens: BW 80 =10 (- 3.035+0.056BL+0.017NP+0.02NF)( R 2 =0.686);for 100-dph specimens: BW 100 =10 (- 3.742+0.069BL+0. 633 · lg (NP)+0. 464 · lg (NF))( R 2 =0.893);and for 130-dph specimens: BW 130 =10 (- 2.472+0.065BL+0.012NP)( R 2 =0.774). Our work clarified the correlation between various morphological traits and body weight of a commercially-important sea cucumber species ( A . japonicus ). Our predictive models for body weight might be useful for the aquaculture and selective breeding of A . japonicus . These models might also provide theoretical support for the indirect selection of traits that are difficult to select directly.     

VIIRS/DNB夜间灯光月度产品插补方法对比——以北京为例

新一代VIIRS/DNB(Visible Infrared Imaging Radiometer Suite Day/Night Band)夜间灯光数据因其具备更精细的时空分辨率、数据不存在饱和现象、不同年份数据可比性强等优点而迅速代替DMSP/OLS(Defense Meteorological Satellite Program's Operational Linescan System)夜间灯光数据成为新的研究热点。但由于杂散光的污染,VIIRS/DNB夏季数据数值缺失严重,致使数据在空间和时间上不连续,因此,插补缺失数据成为后续应用的前提。鉴于此,论文从插补结果异常值、与参照值对比、计算性能三个方面,系统比较了三次样条插值(样条)、三次Hermite插值(Hermite)、灰色预测模型(GM)、三次指数平滑法(指数)4种插补方法的适用性,以期为插补VIIRS/DNB夜间灯光数据提供方法选择的依据。研究结果表明：①异常值比较方面,Hermite法未出现异常值,另外3种算法仅出现少量异常值(0.02%~1.34%);②与参照值的对比方面,Hermite法与参考值接近程度最高,GM接近程度最低,样条法和指数法介于两者中间;③算法性能比较方面,4种方法都具备计算简单、容易编程的特点,但指数法的算法时长是另外3种方法的10倍以上。因此,综合多方表现,当插补月份前后两侧均有足够长的原始数据时,插补效果好、计算速度快、不会出现过冲现象的Hermite法最适宜,样条法次之;当插补月份仅单侧有足够长的数据时,适宜采用指数法(插补效果好、计算速度较慢)或GM(插补效果偏低、计算速度快)进行插补。