HPF(高通数字滤波器)的电网谐波检测技术的研究与应用

为有效地消除电力谐波污染、确保电网运行安全,必须采用有源电力滤波技术;为改善有源电力滤波器的性能,必须采取先进的谐波检测方法、高效的逆变技术。笔者在研究有源电力滤波技术的基础上,对有源电力滤波的关键技术即谐波检测与分离技术,进行了探讨和深入研究,给出了一种HPF(高通数字滤波器)的谐波检测与分离方法,进行了理论验算,利用MATLAB仿真结果对该检测技术进行实验研究。仿真和实验结果表明:该法比常用的LPF(低通数字滤波器LowPassDigitalFilter)的谐波检测分离方法具有更好的检测实时性;在电网电压有畸变时也能达到很高的检测精度;该检测技术应用于混合有源电力滤波器后能大大改善滤波性能。     

复杂矿井通风系统分支阻力可调性数值研究

笔者应用数字实验方法 ,通过调节分支阻力 ,研究它对通风系统的影响。研究结果表明 :当一些分支的阻力调到接近完全隔断风流的极大值时 ,网络分析结果仍然正常 ,不影响迭代技术 ;同样也说明了分支阻力预先输入的可行性 ;各分支阻力的变化对通风系统的影响程度是不一样的 ,这由分支在通风网络中的位置决定 ;通过分析 ,给出了通风系统中两风机的相互影响的情况。     

2010年2月27日智利地震地球球型自由振荡研究

利用中国数字地震台网（CDSN）5个台站的波形资料,采用功率谱密度估计方法,提取了智利地震激发的地球球型自由振荡,并与地球初步参考模型（PREM）的理论自由振荡周期进行对比,发现球型振荡振型周期与地球初步参考模型预测的球型自由振荡周期基本吻合。所得结果可以进一步用来研究地震震源机制和地球内部结构,并对大地震的震源破裂分布给出一定的约束。     

Digital screen use for a road safety campaign message was not associated with road safety awareness of passers-by: A quasi-experimental study

Introduction: Recent evidence suggests fatality risks for cyclists may be increasing in Britain. Understanding how to increase levels of cycling while keeping risk low is paramount. Educating drivers about cyclists may help with road safety, and mass-media messaging is a possible avenue, potentially utilizing digital displays screens in public areas. However, no studies have examined the use of these screens for road safety campaigns. Methods: A quasi-experiment was conducted to examine if digital screens may be effective to raise awareness of a campaign message and encourage recall of car drivers. A digital campaign image was selected that encouraged car drivers and cyclists to ‘look out for each other,’ and stated than 80% of cyclists owned a driving license. Views and knowledge on driver priorities around cyclists were examined before (control) and after campaign exposure (intervention), and tested using regression modelling. Results: 364 people were interviewed over five days. Those interviewed on intervention days were more likely to rank ‘Look out for cyclists’ as being more important compared to those interviewed on control days (OR 1.20), but this was not statistically significant (p = 0.355). Those who said they had seen the image did not rank ‘Look out for cyclists’ higher than those who said they had not seen it (p = 0.778). The disparity between reported and displayed percentage of cyclists with a driving license did not differ between intervention and control days, but was 8% higher amongst those who claimed to have seen the image (p = 0.026). Conclusions: We did not find strong evidence that use of an image on digital screens increased public awareness or recall of a casualty reduction campaign message. Work is needed to investigate the effects of longer-term exposure to road safety images. Practical Applications: Short-term use of digital signage is not recommended for raising awareness of road safety campaigns.     

Monitoring Plant Phenology Using Digital Repeat Photography

Repeated observations of plant phenology have been shown to be important indicators of global change. However, capturing the exact date of key events requires daily observations during the growing season, making phenologic observations relatively labor intensive and costly to collect. One alternative to daily observations for capturing the dates of key phenologic events is repeat photography. In this study, we explored the utility of repeat digital photography for monitoring phenologic events in plants. We provide an illustration of this approach and its utility by placing observations made using repeat digital imagery in context with local meteorologic and edaphic variables. We found that repeat photography provides a reliable, consistent measurement of phenophase. In addition, digital photography offers advantages in that it can be mathematically manipulated to detect and enhance patterns; it can classify objects; and digital photographs can be archived for future analysis. In this study, an estimate of greenness and counts of individual flowers were extracted by way of mathematic algorithms from the photo time series. These metrics were interpreted using meteorologic measurements collected at the study site. We conclude that repeat photography, coupled with site-specific meteorologic measurements, could greatly enhance our understanding environmental triggers of phenologic events. In addition, the methods described could easily be adopted by citizen scientists and the general public as well as professionals in the field.     

云平台助力智慧环保

结合全国以及福建省环境管理信息化的实践经验,提出了狭义的云概念和面向全省各级环境主管部门的基于云平台的信息化建设思路。将新一代信息技术充分融入到环境综合管理应用中去,并从架构、技术应用及效益几个方面进行了分析,是“十二五”期间福建省环境信息化大踏步迈进的有力探索。     

Analysis of 3-D Urban Databases with Respect to Pollution Dispersion for a Number of European and American Cities

Dispersion models require as input various geometrical parameters to calculate the flow field and dispersion characteristics in the urban environment. As a result of recent advances in digital photogrammetry and remote sensing, databases of the actual 3-D geometry of city centre areas are now increasingly available. In this work we outline a procedure to reduce this large amount of data to a structured input for urban pollution dispersion models, i.e. to extract the important flow and dispersion parameters from the urban databases. Based on a review of the scientific literature, we have identified a number of parameters relevant to the modelling of pollution dispersion and atmospheric flows in urban areas. These parameters are: the plan and frontal area densities, the plan and frontal area density as a function of height, the distribution of heights, their standard deviation, the aerodynamic roughness length and the sky view factor.These parameters are obtained by analysing urban Digital Elevation Models (DEMs) which are regularly spaced grids of elevation values. Examples of the parameters calculated from high-resolution databases (with pixel size of about 1 m) for three European (London, Toulouse and Berlin) and two North American (Salt Lake City and Los Angeles) cities are presented and discussed. The calculated aerodynamic roughness length was smaller for the European cities than for the North American ones. A multiplicative correction factor to the aerodynamic roughness length is proposed to include the effect of the variability of the building heights.     

Environmental Impacts of the Emerging Digital Economy: The E-for-Environment E-Commerce?

The Internet-led digital economy is changing both the production and consumption patterns at the global scale. Although great potential exists to harness information technology in general and the Internet in particular and improve the environment, possible negative impacts of e-commerce on the environment should also be considered and dealt with. In this forum, we discuss both the potential positive and negative impacts of e-commerce. Drawing from insights gained from the complexity theory, we also delineate some broad contours for environmental policies in the information age. Given the paradoxical nature of technological innovations, we want to caution the scientific community and policymakers not to treat the Internet as the Holy Grail for environmental salvation.     

基于数字环境模型的大庆市生态环境质量综合评价

黑龙江大庆市作为典型的资源型城市，是人地关系作用最强烈的区域之一，也是生态环境发生急剧变化且具有特色的区域。采用以栅格数据结构为主的多源空间信息，建立了评价生态环境质量的数字环境模型，生成了大庆市生态环境综合评价图。根据评价结果将生态环境质量分为4级，分级结果显示：大庆市生态环境质量以Ⅱ等和Ⅲ等为主，分别占总面积的50．14％和42．65％，而Ⅰ等和Ⅳ等则分别占总面积的2．45％和4．76％。     

铁岭台数字形变短期异常与地震的关系探讨

本文应用铁岭地震台数字形变资料，对松辽盆及其附近地区4次中强震前的异常特征及其异常特征与上述4次地震的关系进行了分析，同时对地震前出现的异常时间、幅度、形态进行了研究。