长时序高光谱图像清晰度影响因素分析

目的 清晰度是评价对地观测成像仪影像数据质量的典型指标之一,可以反映成像仪对地物边缘变化的敏锐程度。已有的对地观测成像仪在轨测试及图像质量评价方法研究中,往往关注遥感影像清晰度是否达标,或监测其变化趋势,未对清晰度变化影响因素进行深入探讨。针对这一问题,本文主要对长时间序列的成像仪成像清晰度的变化以及影响因素进行探讨。方法 以天宫一号高光谱成像仪短波红外谱段0级数据作为研究对象,首先利用改进的基于边缘检测的清晰度算法计算出影像的清晰度,其次将各影像数据对应的成像仪工程参数进行筛选,然后利用Apriori算法对长时间序列高光谱影像的清晰度与成像时刻的工程参数进行关联规则挖掘,利用最小支持度阈值和最小置信度阈值筛选出强关联规则,并附加提升度和余弦对强关联规则进行验证,最后结合3维散点图对影响清晰度的主要因素进行定量分析。结果 经大量测试数据表明,天宫一号高光谱成像仪短波红外谱段影像清晰度较好,影响清晰度的主要因素有太阳高度角、拍摄积分时间以及平台稳定性(包括俯仰角、偏航角和滚动角的稳定性)。太阳高度角与图像清晰度呈正相关关系,即当太阳高度角大于65°时,影像清晰度较高,当太阳高度角小于30°时,影像清晰度较低;平台稳定性与图像清晰度呈正相关关系,即当太阳高度角大于30°且小于65°时,平台稳定性高倾向于得到清晰度较高的图像,平台稳定性低倾向于得到清晰度较低的图像;拍摄积分时间与图像清晰度呈负相关关系。结论 基于关联规则挖掘的长时序高光谱图像清晰度影响因素分析方法是一种有效的分析方法,可以挖掘出与影像清晰度强关联的工程参数。后续可扩大工程参数范围,利用此分析方法进一步研究遥感图像其他指标与工程参数的关联关系。     

Magnetic resonance imaging used for the evaluation of water presence in wood plastic composite boards exposed to exterior conditions

Abstract

Two wood plastic composite (WPC) boards, one experimental and one commercial, were exposed to exterior conditions and evaluated non-destructively using a clinical magnetic resonance imaging (MRI) unit for moisture content (MC) and distribution. The experimental board was exposed in Vancouver, British Columbia, for more than 8 years, and the commercial board was exposed near Hilo, Hawaii, for 2 years. Both boards were characterized in terms of wood content, density, water uptake properties and voids content. The experimental board was additionally destructively analysed for water absorption of the WPC and MC calculated based on the wood content for verification of MRI results. MRI detected the presence of free water and its distribution in both of the WPC boards. Fibre saturation in the experimental board was found to be about 22–24%, in comparison to 25–30% present in most wood species. There was good correlation between the detection of free water by MRI and by destructive testing. Magnetic resonance images showed various major points of water entry in the WPC boards such as the support area, the cut ends, the dripping edge and the sides of the boards. For the experimental board, significant water entry also occurred at the upper exposed surface.     

Development of a Clean Biodiesel Fuel in Hong Kong Using Recycled Oil

All fuel usage produces air pollutants, causing local and trans-boundary air pollution and acid rain problems. Biodiesel is a clean renewable fuel with properties similar to diesel but produced from renewable resources such as vegetable oils and animal fats. Although this fuel has been developed some two to three decades ago, it is not commonly used, mainly due to the higher production cost involved. Due to the increasing concern on environmental protection, a lot of researches on the usage of this fuel are conducted in recent years. To study the characteristics of this fuel, a special biodiesel fuel is produced using waste cooking oil and animal fat from restaurants as feedstock. Reusing of these wastes has both the benefit of producing a cleaner fuel and waste cycling. Tests of the fuel with different proportions of diesel have been conducted on various diesel engines and the results obtained are encouraging. The environmental benefits and suitability of this fuel to Hong Kong to reduce air pollution problems are discussed based on the assessment results.     

Quantification of two polyacetylenes in Radix Ginseng and roots of related Panax species using a gas chromatography-mass spectrometric method

A sensitive method for quantitating the pharmacologically active polyacetylenes panaxynol and panaxydol in Radix Ginseng was developed using a capillary gas chromatography-mass spectrometric (GC-MS) method. The detection mode of selected ion monitoring (SIM) allowed sensitive and selective quantitation of the two compounds in ginseng. Method validation showed that the GC-MS method has much lower detection and quantitation limits than the high-performance liquid chromatography (HPLC)-UV method. This indicates that GC-MS is particularly useful for the analysis of polyacetylene compounds, which have relatively low abundances compared with ginsenosides in ginseng. Based on the quantitative results of different types of ginseng herbs, it was found that the panaxydol and panaxynol contents were higher in forest ginseng than in cultivated ginseng. This method was further applied to the quantitative analyses of panaxynol and panaxydol in Radix Notoginseng and American ginseng. The ratio of panaxydol to panaxynol can be utilized as a marker for differentiating ginseng, notoginseng, and American ginseng. This study introduces the first GC-MS method for the quantitative analysis of polyacetylenes in herbs of the Panax genus.     

The Transport of Escherichia coli Through Freeze-Fractured Clay Soil

Little is known about the transport of microorganisms through freeze-fractured clay soils. Normally consolidated clay (NCC) and compacted clay (CC) columns (representing a natural clay barrier and a compacted barrier, respectively) were exposed to six consecutive freeze–thaw cycles and permeated for 21 days with an Escherichia coli cell suspension (approximately 1?×?10⁷ colony forming units (CFU)/mL) containing a 2.1-mM bromide tracer. An unfractured sand column was also examined for comparison with the clay columns. While no E. coli was detected in the effluent of both untreated NCC and CC control clay columns, a relatively low density of E. coli (between 228 and 270 CFU/mL compared to 1?×?10⁷ CFU/mL in the influent) was first detected in the effluent of the freeze-fractured NCC and CC columns at 0.29 and 0.31 pore volumes (or at 5.4 and 4.1 h), respectively. It took 11 min for a full breakthrough of E. coli through the sand column, but only about 0.1% of the influent E. coli density was detected in the effluents of the freeze-fractured NCC and CC columns at day 21. These observations show that despite the high bacterial retention capacity of the freeze-fractured clay columns, the fractures were large enough for the E. coli to flow through. Based on batch sorption tests and the permeation data, it is estimated that 18%, 7%, and 84% of the freeze-fractured NCC, CC, and sand columns would be exposed to the influent, respectively, under a full E. coli breakthrough condition. Our data show that the high bacterial retention capacity of clay barriers can be compromised by freeze–thaw conditions.     

Vitamin K requirement and reproduction in bromadiolone-resistant Norway rats

BACKGROUND: Nucleotide polymorphisms in the VKORC1 gene can be linked to anticoagulant rodenticide resistance in Norway rats (Rattus norvegicus Berkenhout). This provides a fitness advantage to rats exposed to anticoagulant actives, but may also cause fitness costs. The vitamin K requirement and reproductive parameters of bromadiolone‐resistant rats (Westphalian resistant strain; VKOR variant Tyr139Cys) and bromadiolone‐susceptible Norway rats were compared. RESULTS: At vitamin K deficiency, blood clotting times increased in all homozygous resistant males within 8 days and in 80% of homozygous resistant females within 15 days. There was little effect on blood clotting in heterozygous males and no effect in heterozygous females and VKOR wild‐type individuals. Litter size was about 20% higher in sensitive pairs compared with resistant pairs. Testes growth, male gonad weight, sperm motility and testis cell concentration were unaffected by the mutation. CONCLUSIONS: The VKOR variant Tyr139Cys causes considerable physiological cost in Norway rats in terms of vitamin K requirement and reproduction. This may affect the distribution and spread of resistant individuals in the wild. Decreased litter size of resistant parents seems to be due to lowered female reproductive performance, as there was no significant effect of the mutation on any aspects of male reproduction considered, but this requires further study. Copyright © 2011 Society of Chemical Industry     

抗稻瘟病水稻材料谷梅2号中主效抗稻瘟病基因的成簇分布

应用由籼稻组合中156/谷梅2号衍生的304个重组自交系,构建了由177个标记组成、覆盖12条水稻染色体的连锁图谱,定位控制水稻稻瘟病抗性的主效基因。前期定位的控制对中国稻瘟菌菌系92 183（小种ZC15）穗瘟抗性的基因Pi25(t)的位置得到进一步确认,位于第6染色体标记A7和RG456之间,与A7和RG456的遗传距离分别为1.7和15 cM;发现群体对菲律宾稻瘟菌菌系Ca89（4谱系）的叶瘟抗性由单基因控制,将该暂命名为Pi26(t)的基因定位于第6染色体标记B10和R674之间,与B10和R674的遗传距离分别为5.7和25.8 cM。两个基因座位上的抗病等位基因均来源于谷梅2号,表明谷梅2号中存在控制水稻稻瘟病抗性的基因簇。     

用于水稻突变体大量筛选的DNA微量快速提取法

介绍了一种高通量水稻DNA微量快速抽提法。该方法特别适用于精细作图群体和大型突变体库的筛选鉴定,不仅通量大、速度快,而且可以确保足够的DNA浓度和纯度。DNA质量可以确保一般的PCR扩增,包括SSR检测以及应用于TILLING（targeting induced local lesion in genome）分析。     

A Technical Efficiency Analysis of Hawaii's Aquaculture Industry

This study examines the technical efficiency (TE) of aquaculture farms in Hawaii. Policy makers and industry participants interested in assessing the economic outlook of aquaculture production not only have to assess measures of profitability and financial health, but also measures of production efficiency. We estimate the TE of the state's aquafarms with a data envelopment analysis (DEA) model. Using data from the US Census of Agriculture, we examine TE measures of the population of Hawaii's aquafarms across different types of farms and over time. The results show that only 12% of the farms in 2007 may be classified as efficient, with a steady decline in efficiency over time. We find TE was related to the size of farm, full‐time farms were significantly more efficient than part‐time farms and that the average excess real inputs for land and labor have slightly fallen over time. The sub‐sector analysis revealed a strong variation of TE across different type of farms. With few farms operating on the frontier, the findings of this study suggest that the majority of the farms could improve their TE.