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281.
水质基准是制定水质标准限值的重要依据,是科学的水质管理体系的重要组成部分。我国水体污染形势严峻,区域环境差异明显,亟需建立适合我国水环境特征的水质基准作为水质控制和管理的理论依据。文章对我国水质基准的概况、水质基准方法学、水质基准研究进展、存在问题及发展趋势进行了系统论述,以期为我国水质基准的研究提供参考与支撑。  相似文献   
282.
十二五"期间全国PM_(10)浓度陡增导致了达标城市比例降低,影响了《国家环境保护"十二五"规划》空气质量指标的完成。通过对PM_(10)浓度时间和空间变化分析,得出《环境空气质量标准》(GB3095-2012)的逐步实施对全国PM_(10)浓度的异常变化有着显著影响。新标准的发布施行,促进了PM_(10)监测仪器和方法更新升级,大幅收严了监测数据统计的有效性,提升了监测数据的质量控制水平,从主观和客观上更加有效的提高了监测数据的精度。  相似文献   
283.
计算机决策支持系统已经比较成熟地应用于许多行业,但在生态工业园建设管理中尚未得到应用。本文结合生态工业园建设管理的特点,分析了生态工业园决策支持系统开发的功能要求,提出了一种基于GIS、数据仓库、数据挖掘以及联机分析技术,并结合专家系统的生态工业园智能决策支持系统的框架,探讨了决策支持系统在生态工业园建设管理中的发展前景。  相似文献   
284.
Introduction: Traffic safety issues associated with taxis are important because the frequency of taxi crashes is significantly higher than that of other vehicle types. The purpose of this study is to derive safety implications to be used for developing policies to enhance taxi safety based on analyzing intrinsic characteristics underlying the cause of traffic accidents. Method: An in-depth questionnaire survey was conducted to collect a set of useful data representing the intrinsic characteristics. A total of 781 corporate taxi drivers participated in the survey in Korea. The proposed analysis methodology consists of two-stage data mining techniques, including a random forest method, with data that represents the working condition and welfare environment of taxi drivers. In the first stage, the drivers’ intrinsic characteristics were derived to classify four types of taxi drivers: unspecified normal, work-life balanced, overstressed, and work-oriented. Next, priority was determined for classifying high-risk taxi drivers based on factors derived from the first analysis. Results: The derived policies can be categorized into three groups: ‘the development of new policies,’ ‘the improvement of existing policies,’ and ‘the elimination of negative factors.’ Establishing a driving capability evaluation system for elderly drivers, developing mental health management programs for taxi drivers, and inspecting the taxi's internal conditions were proposed as new policies. Improving the driver's wage system, supporting the improvement of rest facilities, and supporting the installation of security devices for protecting taxi drivers are methods for improving existing policies to reinforce the traffic safety of taxi drivers. Last, restricting overtime work for taxi drivers was proposed as a policy to eliminate negative factors for improving taxi traffic safety. Practical Applications: It is expected that by devising effective policies using the policy implications suggested in this study, taxi traffic accidents can be prevented and the quality of life of taxi drivers can be improved.  相似文献   
285.
本文介绍了使用超声波和磁粉探伤技术对某大吨位铸造用桥式起重机主起升系统吊具金属结构母材及其焊缝探伤检验的一些情况,重点阐述了探伤检验部位确定的方法和依据。  相似文献   
286.
基于模糊系统与神经网络融合的故障诊断方法   总被引:5,自引:1,他引:4  
提出一种基于模糊系统(FS)与神经网络(NN)融合的系统故障诊断方法。此法把模糊系统与神经网络融合在一起,通过神经网络的学习来生成和调整模糊系统的隶属函数,充分发挥各自优点,更有效地对系统出现的故障进行诊断。对系统进行了仿真,并得出了比较满意的结果。  相似文献   
287.
Protected areas present a global heritage. Assessing conservation achievements in protected areas is of crucial importance with respect to the on-time delivery of international biodiversity conservation targets. However, monitoring data from publicly accessible databases for comparative studies of conservation achievements in the protected areas of the world are very scarce, if not non-existent. At first glance this is surprising because, with regards to protected areas, at least according to well established protected area management guidelines and widely accepted public mandates, a great deal of monitoring work and data gathering is to be conducted. This would imply that data on changes of biodiversity in protected areas could be expected to exist, and the constant progress in information technologies and Web tools engenders hope that some of it might even be available online for the global public. This review article presents the results of an extensive online search and review of existing monitoring data from freely accessible online databases for its use in an assessment of conservation achievements in a larger sample of protected areas. Results show two contrary sides to the status quo of accessible data from the World Wide Web for conservation science: data overkill and data scarcity with poor metadata provision. While ever more research is, in fact, based on open-access online data, such as extrapolations of species ranges used in conservation management and planning, it remains almost impossible to obtain a basic set of information for an assessment of conservation achievements within a larger number of protected areas. This awareness has triggered a detailed discussion about the discrepancies in sharing data at the level of protected areas; mismatching relationships between expected activities in protected areas and the capacity for delivering these requirements are certainly among the main challenges. In addition, the fear of data misuse potentially resulting in harm for nature, careers, and competencies still seems to be a critical barrier strictly controlling the willingness to share data. Various initiatives aimed at tackling technical and cultural obstacles are introduced and discussed to reach the goal of a modern resource management based on adaptive management using digital opportunities of the new millennium for a sustainable global village.  相似文献   
288.
Neal R. Haddaway 《Ambio》2014,43(5):703-706
Much of the scientific literature in existence today is based on model systems and case studies, which help to split research into manageable blocks. The impact of this research can be greatly increased in meta-analyses that combine individual studies published over time to identify patterns across studies; patterns that may go undetected by smaller studies and that may not be the main subject of investigation. However, many potentially useful studies fail to provide sufficient data (typically means, true sample sizes, and measures of variability) to permit meta-analysis. Authors of primary research studies should provide these summary statistics as a minimum, and editors should require them to do so. By putting policies in place that require these summary statistics to be included, or even those that require raw data, editors and authors can maximize the legacy and impact of the research they publish beyond that of their initial target audience.  相似文献   
289.
In environmental monitoring, variables with analytically non-detected values are commonly encountered. For the statistical evaluation of these data, most of the methods that produce a less biased performance require specific computer programs. In this paper, a statistical method based on the median semi-variance (SemiV) is proposed to estimate the position and spread statistics in a dataset with single left-censoring. The performances of the SemiV method and 12 other statistical methods are evaluated using real and complete datasets. The performances of all the methods are influenced by the percentage of censored data. In general, the simple substitution and deletion methods showed biased performance, with exceptions for L/2, Inter and L/√2 methods that can be used with caution under specific conditions. In general, the SemiV method and other parametric methods showed similar performances and were less biased than other methods. The SemiV method is a simple and accurate procedure that can be used in the analysis of datasets with less than 50% of left-censored data.  相似文献   
290.
● Data quality assessment criteria for MP/NPs in food products were developed. ● Data quality of 71 data records (69 of them only focused on MPs) was assessed. ● About 96% of the data records were considered unreliable in at least one criterion. ● Improvements need to be made regarding positive controls and polymer identification. ● A mismatch between MP/NPs used in toxicity studies and those in foods was recorded. Data on the occurrence of microplastics and nanoplastics (MP/NPs) in foods have been used to assess the human health risk caused by the consumption of MP/NPs. The reliability of the data, however, remains unclear because of the lack of international standards for the analysis of MP/NPs in foods. Therefore, the data quality needs to be assessed for accurate health risk assessment. This study developed 10 criteria applicable to the quality assessment of data on MP/NPs in foods. Accordingly, the reliability of 71 data records (69 of them only focused on MPs) was assessed by assigning a score of 2 (reliable without restrictions), 1 (reliable but with restrictions), or 0 (unreliable) on each criterion. The results showed that only three data records scored 2 or 1 on all criteria, and six data records scored 0 on as many as six criteria. A total of 58 data records did not include information on positive controls, and 12 data records did not conduct the polymer identification, which could result in the overestimation or underestimation of MP/NPs. Our results also indicated that the data quality of unprocessed foods was more reliable than that of processed foods. Furthermore, we proposed a quality assurance and quality control protocol to investigate MP/NPs in foods. Notably, the characteristics of MP/NPs used in toxicological studies and those existing in foods showed a remarkable discrepancy, causing the uncertainty of health risk assessment. Therefore, both the estimated exposure of MP/NPs and the claimed potential health risks should be treated with caution.  相似文献   
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