基于特征和主动轮廓算法的运动果蝇识别与跟踪研究

多目标跟踪是视频监控等领域的一项关键技术。阐述目标跟踪算法的研究现状,运用灰度阈值分割,基于特征和主动轮廓跟踪方法实现对多只运动果蝇进行目标识别与跟踪。运用C#以及emgu开发应用程序予以系统实现。经验证,该系统识别率高,具有稳健的跟踪效果。     

基于Matlab的复杂背景下叶片图像提取方法

将需要研究的植物叶片从复杂的背景下提取出来是后期图像理解和图像分析的关键。、主要是在支持向量机的基础上将叶片从复杂的环境下提取出来,并与H通道的（）’rSu算法和最大直方图熵与GA相结合的图像分割算法相比较,在Matlab环境下进行仿真分析,结果显示支持向量机在复杂背景下进行图像分割方面有优势。     

Impact of aquaculture feed technology on fish income and poverty in Kenya

ABSTRACT

The impacts of improved agricultural technologies on smallholder households in Africa are well documented in the literature. However, the literature on the welfare impacts of aquaculture technologies, especially in the context of smallholder households, is very scanty. This paper applies the propensity score matching technique to household survey data to examine the impact of improved feed technology on fish income and poverty in Kenya. After controlling for observable household characteristics, the results indicate that improved feed technology increases aquaculture income and reduces poverty among fish farming households. Specifically, the income effect of the technology is 23–37%, with resultant poverty reduction effect of 19–23% points. Evidence from the study indicates that the likelihood of adopting improved feed in Kenya will surge with improved extension service delivery, access to government subsidized feed, and easy market access for purchasing improved feed and sale of mature fish.     

基于模板匹配的多目标水稻灯诱害虫识别方法的研究

 水稻灯诱害虫的识别与计数在水稻田间害虫监测中是非常重要的。由于水稻害虫被黑光灯诱集后姿态各异,存在虫体残缺现象,增加了图像自动识别的难度。在获取水稻灯诱害虫非粘连图像基础上,利用模板匹配和K折交叉验证方法进行多目标水稻灯诱害虫的识别。首先,提取每个水稻害虫图像中包括颜色、形态和纹理共156个特征参数;然后,利用主成分分析法进行数据降维,选取前6个主成分作为害虫特征参数;最后,根据每种灯诱害虫的姿态确定模板数,通过模糊C均值获得聚类中心作为模板参数,分别利用单模板和多模板匹配方法进行水稻害虫的识别。结果表明,针对姿态各异且有虫体残缺的多目标水稻灯诱害虫,多模板和单模板匹配法的识别率分别为83.1%和59.9%。     

产品设计过程中质量知识的匹配方法

提出了一种产品设计过程中基于语义距离的设计质量知识的表示及匹配方法,将产品设计过程划分为5个阶段,构建产品设计质量信息模型。依照设计质量信息模型,对设计任务、设计人员和设计质量信息进行分析,以任务元、对象元、信息元来构建三者的形式化描述体系,并建立其数据结构。利用HNC(概念层次网络)知识库,基于语境框架文本相似度计算,并结合语义距离计算,实现了文本间相似度的精确量化和比较。以注塑机方案设计过程为例,实现了设计质量信息匹配,验证了该方法的有效性。     

Risk of establishment of non-indigenous diseases of citrus fruit and foliage in Spain: An approach using meteorological databases and tree canopy climate data

Based on macroclimate comparisons of monthly means of temperature and rainfall, the Mediterranean-type climate might be considered unfavorable for the establishment of the quarantine pathogens of fruit and foliage of citrus regulated by the EC Council Directive 2000/29. The presence of free water on the canopy during periods with temperatures favorable for disease development seems to be limited by the characteristic rainless summer. However, our field study showed that due to the formation of dew, rainfall and rain days were not positively correlated with canopy wetness. Dew periods were quite frequent during summer nights with temperatures over 15°C and even 20°C. Nevertheless, wetness periods were seldom continuous and they were usually interrupted by dry periods approximately 10–14 h long. In contrast to some endemic foliar pathogens such asAlternaria alternata, no data are currently available on the performance of these non-indigenous pathogens under interrupted wetness conditions. Due to the lack of rain during the summer in semi-arid areas, the natural spread of rain-disseminated citrus pathogens, such asElsinoë spp. andXanthomonas axonopodis pv.citri, might be rather limited. However, windborne pathogens, such asGuignardia citricarpa andPseudocercospora angolensis, would have considerable potential for dissemination under the Mediterranean climate. We consider that more information about the effect of microclimate on the epidemiology of these diseases is needed to estimate accurately their risk of establishment in Spain and in other citrus-growing countries of the Mediterranean Basin.     

Can catch share fisheries better track management targets?

Fisheries management based on catch shares – divisions of annual fleet‐wide quotas among individuals or groups – has been strongly supported for their economic benefits, but biological consequences have not been rigorously quantified. We used a global meta‐analysis of 345 stocks to assess whether fisheries under catch shares were more likely to track management targets set for sustainable harvest than fisheries managed only by fleet‐wide quota caps or effort controls. We examined three ratios: catch‐to‐quota, current exploitation rate to target exploitation rate and current biomass to target biomass. For each, we calculated the mean response, variation around the target and the frequency of undesirable outcomes with respect to these targets. Regional effects were stronger than any other explanatory variable we examined. After accounting for region, we found the effects of catch shares primarily on catch‐to‐quota ratios: these ratios were less variable over time than in other fisheries. Over‐exploitation occurred in only 9% of stocks under catch shares compared to 13% of stocks under fleet‐wide quota caps. Additionally, over‐exploitation occurred in 41% of stocks under effort controls, suggesting a substantial benefit of quota caps alone. In contrast, there was no evidence for a response in the biomass of exploited populations because of either fleet‐wide quota caps or individual catch shares. Thus, for many fisheries, management controls improve under catch shares in terms of reduced variation in catch around quota targets, but ecological benefits in terms of increased biomass may not be realized by catch shares alone.     

基于邻域直方图的玉米田绿色植物图像分割方法

为了准确分割绿色植物与土壤背景,克服田间环境的复杂性,比如植物阴影、残渣的存在和光照强度变化等外界因素带来的影响,采用图像处理和支持向量机方法,以超绿特征(2G-R-B)灰度图像为研究对象,以像素点邻域组成的灰度直方图特征作为输入特征向量,通过试验选出最佳训练参数和最优邻域窗口模型。实验表明,该方法适应不同光照强度,并且可以减小噪声、植物阴影和残渣对图像分割带来的影响,得到完整的分割图像。     

犬血型与安全输血研究进展

综述了犬血型系统、血型鉴定、交叉配血、供血犬选择以及输血反应等与安全输血相关的各方面的研究进展,系统探讨了临床上如何对犬进行安全、有效输血以及当前存在问题。     

农村学生高等教育选择的个体异质性影响及长期收入回报研究

高等教育进入大众化阶段,但高校中农村学生比例偏低。利用CFPS 2012年的调查数据,采用Logit回归方法,从个体特征、家庭特征和区位特征三个维度系统分析个体异质性对农村学生高等教育选择的影响,进而在控制个体差异的基础上,采用PSM方法测度农村高等教育的收入回报,设定不同的年龄分组,研究高等教育的长期收入回报,并分析东中西部农村高等教育的长期收入回报是否存在区域上的差异。结果表明,健康状况、医疗保险、智力、理解能力、外貌、父母学历和家庭地位等特征显著影响农村学生是否接受高等教育的选择;接受高等教育的农村个人收入要高于不接受高等教育时的收入;从长期来看,接受高等教育和没有接受高等教育的农村个人之间的收入差异随着年龄的增长呈现不断上升的趋势;西部地区高等教育对农村个人收入的长期影响显现得最早,中部地区次之,东部地区最晚。在此基础上,为缩小教育差距、实现高等教育公平,提出教育资源投入向农村落后地区倾斜、高校针对农村贫困学生制定合理的教育补助规模、农村家庭转变传统封闭的教育观念鼓励子女接受高等教育的政策建议。