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81.
殷勇  梁西腾  丁圣陶  叶关根 《测绘科学》2012,37(5):76-77,80
等高线注记是一种特殊的曲线注记,它除了有普通曲线具有的分段注记以及在曲线光滑部分注记等问题外,还存在字头朝向问题和沿辅助曲线注记的问题。本文提出了新的分段注记算法以及高程朝向判断方法,使等高线注记有更好的注记效果。  相似文献   
82.
Reducing marine-based public health risk requires strict control of several attributes of seafood products, often including location and conditions of catch or aquaculture, processing, and handling throughout the supply chain. Buyers likely will also be interested in other attributes of these products such as eco-friendliness or taste. Development of markets for improved safety, as well as for other quality attributes, requires an effective certification and tracking of these attributes as well as their communication to buyers. Several challenges must be met if labeling, particularly consumer labeling, is to support the development of markets for improved seafood safety.  相似文献   
83.
Surveillance systems for foodborne disease vary in capacity by country, especially for marine-related illnesses. Generally, the more developed the country is, the more funding that is put into its surveillance programs, but no country has an outstanding system that could serve as a model for all others. An additional problem is lack of consistency. Approaches to surveillance and available resources change over time, so that apparent trends may reflect more of an administrative function. Most countries have some passive system that allows data on foodborne illnesses to be sent to centralized authorities where summaries are generated. However, these depend on the uneven quality of the source data that vary according to the resources allocated at the local level. Active surveillance systems collect data targeted to answer specific epidemiological questions more efficiently, but at such a high cost that most countries do not have the resources, except on a occasional basis. There is also the issue of what to do with the collected data. There has to be a conscious effort to translate the problems identified from the surveillance programs to consider strategies for prevention and control of foodborne disease. Otherwise, there is little value in having these kinds of monitoring programs. Another problem is lack of coordination in surveillance systems between most countries, so that information can be rapidly and efficiently shared. That being said, surveillance over the years had generated much interesting information on how disease agents are transmitted through the food supply, and where contamination and growth by pathogens in the food production and preparation chain typically occur. In addition, attempts are being made to create regional networks in different parts of the world usually initiated by organizations like WHO and PAHO. The kinds of information collected and programs being introduced are discussed in examples taken from both the developed and less developed world, followed by a series of recommendations for improving surveillance on a global basis. A recent burden in the surveillance system is the potential for a deliberate attack on the food supply with agents not usually involved with foodborne illness. At least in the US, a major concern is for the rapid detection and containment of a massive contamination of the food supply.  相似文献   
84.
The seafood industry has become increasingly interconnected at a global scale, with fish the most traded commodity worldwide. Travel to the farthest reaches of the oceans for capture is now common practice, and subsequent transport to market can require hundreds to thousands of miles of travel by sea and air. Refrigeration of seafood products is generally required at all stages of the journey from ocean to dinner plate, resulting in substantial energy expenditure. Energy input for aquaculture (including mariculture) products can also be high, namely due to the large amounts of feed required to support fish growth. As a result of these factors, the seafood industry has a substantial carbon footprint. Surprisingly, however, carbon footprints of seafood products are rarely integrated into assessments of their sustainability by eco-labels, sustainability certification, or consumer seafood sustainability guides. Suggestions are provided here for how carbon footprints could be incorporated within seafood sustainability schemes.  相似文献   
85.
Seafood fraud is widespread and undermines attempts to achieve more sustainable fisheries and seafood trade. Deliberate mislabelling of fish was first detected in South Africa in 2009, exposing the lack of coherent or explicit naming and labelling regulations. It was followed by considerable media coverage and public outrage. This catalysed a series of events that led to the creation of a new space of engagement where scientists, academics, and industry could begin to jointly solve the issue of seafood mislabelling. This paper first evaluates and identifies the shortcomings of the existing policy and regulatory framework applicable to seafood naming and labelling in South Africa. Next, it examines approaches of some other countries to deal with seafood (mis)naming, and puts forward a set of suggestions that could be used to improve the status quo in South Africa, or any other country in a similar position. Finally, it reports on subsequent developments over the past five years following the seafood scandal, including the formation of a working group with representation from across the seafood supply chain, regulatory bodies, and experts: resulting in a submission of a proposal for a new national standard for seafood market names in South Africa. These findings show how diverse actors can work in a cooperative and practical manner, to solve a common problem. Finally, it highlights the importance of the “bridging” role that non-governmental organisations can play in achieving this.  相似文献   
86.
复杂构造建模技术综述   总被引:2,自引:1,他引:1       下载免费PDF全文
目前复杂构造建模技术是地震资料处理中的技术瓶颈.本文主要介绍了目前国内外常用的复杂构造建模技术,包括层位标定技术、地层追踪技术、面块切片技术,以及相干体、方差体和三维可视化技术等,并分析了各自的适应性.  相似文献   
87.
利用OpenStreetMap数据进行高空间分辨率遥感影像分类   总被引:1,自引:0,他引:1  
针对高分辨率遥感影像分类样本标注困难的问题,提出了一种利用OpenStreetMap (OSM)数据自动获取标注样本的方法。与现有的利用OSM数据进行分类的方法不同,该方法加入了空间特征以弥补单独使用光谱特征分类的不足。首先,基于OSM数据提供的地物类别和位置信息进行样本标注,为了降低OSM数据中少量错误信息对分类结果的影响,采用聚类分析的方法对样本进行提纯;其次,使用形态学轮廓来提取影像的结构特征,挖掘高分辨率遥感影像丰富的空间信息,与光谱特征相叠加并输入分类器进行分类。试验证明,本文提出的方法能够有效避免人工样本标注所需要的人力物力;同时,联合影像的光谱空间特征能够更好地描述地物特性,得到较高的分类精度。  相似文献   
88.
In this study, we examined the impact of temperature on the carbon and nitrogen trophic transfers from a macroalga to a macro‐grazer by the use of dual 13C‐ and 15N‐labeling. Using an experimental approach in mesocosms, individuals of the urchin Psammechinus miliaris were maintained for 1 month at 17°C (mean summer temperature in the Bay of Brest) and at 20°C (maximum summer temperature) and fed with 13C‐ and 15N‐labeled Solieria chordalis. The results showed that the urchins’ 13C uptake was 0.30 µg13C g dry weight (DW)?1 at 17°C and 0.14 µg13C g DW?1 at 20°C at the end of the experiment. The lower uptake at the higher temperature may be attributed to a decrease in metabolic activity at 20°C, involving lower feeding and/or respiration rates. Conversely, no significant effect of temperature was detected on 15N uptake. At the end of the experiment, the urchins’ 15N uptake was 0.04 µg15N g DW?1 at 17°C and 0.03 µg15N g DW?1 at 20°C. This suggests that temperature may affect carbon and nitrogen trophic fluxes differently. The use of dual isotope labeling offers interesting prospects and needs to be further extended in order to better understand trophic interactions in marine communities and the consequences of current environmental changes, such as global warming.  相似文献   
89.
"蓝色粮仓"是包含海产品生产、加工及海洋水产资源环境养护等众多关联产业的集合体,是保障我国粮食和营养安全、推进海洋强国战略和国家生态文明建设的重大举措。然而,"蓝色粮仓"关联产业粗放式的发展模式给近海渔业资源及生态环境造成了不同程度的损害,制约了我国"蓝色粮仓"的可持续发展。文章系统地分析了我国"蓝色粮仓"关联产业的发展现状与存在资源衰退状况严重、近海捕捞难以维持、养殖环境问题突出、水产品安全问题凸显等问题,并提出了控制近海捕捞产量,推进捕捞业转型升级、优化海水养殖模式,提高生态和经济效益、加强水产品精深加工,提高产业价值链、加强渔业资源保育工作、完善各项保障措施等对策,以求为我国"蓝色粮仓"建设决策提供参考依据。  相似文献   
90.
The human appetite for seafood has intensified and so has overfishing and damage to marine ecosystems. Recently, the response to the fisheries crisis has included a considerable effort directed toward raising the seafood awareness of consumers in North America and Europe. The resulting campaigns aim to affect the seafood demand and to lead to a sustainable seafood supply. Though there are indicators of some regional successes, lack of support by the Asian market and the proliferation of self-serving seafood labels are but two of the many significant limitations of these campaigns. This contribution investigates the difficulties and successes of seafood awareness campaigns, as well as the need for indicators of campaign effectiveness.  相似文献   
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