小型高精度恒温箱设计与应用

介绍了一种用于给倾角传感器提供恒温环境的小型高精度恒温箱的设计与实现。此恒温箱要求体积小、温度控制精度在±0．05℃以内。文中介绍了恒温箱的结构设计和温控算法并给出了详细的实验结构,证明了研制的这种高精度恒温箱不仅其控温精度高,且与同类产品比其体积小,安装调试方便。     

Applying Fuzzy Logic to Assess Human Perception in Relation to Conservation Plan Efficiency Measures Within a Biosphere Reserve

The objective of this study is to present an efficiency-perception impact assessment based upon the integration of fuzzy logic (FL) of the "Productive Reconversion" conservation program (PRP) instituted by the Mexican government, in the upper Gulf of California and the Colorado Delta Biosphere Reserve. This approach enables environmental analysts to deal with the intrinsic imprecision and ambiguity associated with people's judgments and conclusions. The application of FL to the assessment of program efficiency is illustrated in this work, demonstrating how subjective perceptions can be converted into quantitative values easy to evaluate during the decision-making process.     

The effects of color and light on indoor wayfinding and the evaluation of the perceived environment

This study was designed to explore the effects of color and light on indoor wayfinding and the subjective judgments of those perceiving the environment. Furthermore, how problems experienced in buildings with complex floor plans and successive spaces are addressed using variables such as color, brightness, and correlated color temperature through a desktop virtual reality environment. The experiment was conducted with the participation of 102 university students who experienced the indoor environments with various color and light variables, and evaluated these environments using concrete concepts like clear/blurry, attractive/unattractive, navigable/unnavigable and inviting/repellent. The scores for attractiveness and remembrance of warm colors were found to be higher than those for other colors, and the median scores for the positive perception of correlated color temperature were found to be higher than those concerning high and low level temperatures. However, it was confirmed that the use of warm and cool colors in indoor environments with low light levels were not taken into consideration by users of a space and were perceived negatively. Moreover, it was determined that compared to the males, females preferred high brightness levels.     

Deposition in boreal forests in relation to type, size, number and placement of collectors

Open precipitation and throughfall was collected at a Norway spruce stand in Finland using funnel-type collectors and at a black spruce stand in Canada using trough-type collectors. The presence or absence of a rim on the funnel, funnel diameter (9, 14 and 20 cm) and length of sampling period (1, 2 and 4 weeks) on monthly values were evaluated at the Norway spruce stand, and the number of collectors required for defined levels of accuracy and precision of throughfall loads to be reached and the influence of the spatial arrangement of collectors on solute concentrations was studied at both stands. The presence of a rim had no significant effect on open precipitation and throughfall amounts, but did on throughfall DOC, Ca²⁺, Mg²⁺, K⁺, Na⁺ and Cl⁻ ion loads. Deposition loads increased with decreasing funnel diameter; for open precipitation, this was due to increased catch efficiency while for throughfall the increase was attributed to canopy interaction and leaching of litter trapped in the collectors. Calculated monthly H⁺ loads decreased and those for all other constituents increased with collection period length. Using 15 collectors at the Norway spruce stand would allow throughfall loads to be determined to within 20% of the true mean weekly value with a confidence level of 95% for most solute, but not for NH₄ ⁺–N, NO₃ ⁻–N, Mg²⁺ and SO₄ ²⁻-S. Using 15 trough collectors, the same confidence level at the more heterogeneous black spruce stand would only be achieved for H⁺, Cl⁻, DOC and SO₄ ²⁻-S loads. In both stands, using either random or systematic placements of throughfall collectors gave similar results.     

Systems In Organic Dairy Production

The aim of this study was to explore stakeholder perceptions of the contribution of an Automatic Milking System (AMS) to sustainable development of organic dairy production in Denmark and the Netherlands. In addition, reasons for the current difference in AMS use on organic dairy farms between both countries were explored. To answer above mentioned aims, farmers and advisors in both countries were interviewed using a focus group approach. Questions of the interviews were based on a literature review on sustainability issues affected by introduction of AMS. Participants expressed no moral problems regarding AMS use. They, however, pointed out uncertainty about the economic gain, difficulties with grazing, adaptation problems to technology, and image problems towards consumers. The latter results from a reduction in grazing time affecting both animal welfare and product quality. The participants did not recognize eutrophication, as result of high stocking density on farmstead lots, as a problem caused by AMS. The milk quality problem related to AMS use, although acknowledged as crucial towards consumers, was not prioritized very highly, especially not by the farmers in both countries. All groups were, however, unanimous in their perception of how important image was as far as the consumers are concerned. The perception analysis revealed that Dutch participants were more concerned about the economic payoff of AMS use, and showed more reluctance towards enlargement than Danish ones. In addition, they acknowledged the small-scale naturalness of organic production. These differences in perception could possibly explain observed differences in AMS use in organic dairy production between Denmark and the Netherlands.     

Application of multiwalled carbon nanotubes treated by potassium permanganate for determination of trace cadmium prior to flame atomic absorption spectrometry

In this study we investigated the enrichment ability of oxidized multiwalled carbon nanotubes (MWCNTs) and established a new method for the determination of trace cadmium in environment with flame atomic absorption spectrometry.The MWCNTs were oxidized by potassium permanganate under appropriate conditions before use as preconcentration packing.Parameters influencing the recoveries of target analytes were optimized.Under optimal conditions,the target analyte exhibited a good linearity (R~2=0.9992) over the concentration range 0.5-50 ng/ml.The detection limit and precision of the proposed method were 0.15 ng/ml and 2.06%, respectively.The proposed method was applied to the determination of cadmium in real-world environmental samples and the recoveries were in the range of 91.3%-108.0%.All these experimental results indicated that this new procedure could be applied to the determination of trace cadmium in environmental waters.     

水污染预警溯源技术应用案例研究

以南方某工业园区为例,研究了水污染预警溯源技术在园区企业污水排放精准监管中的应用。该技术提出污染源“水质指纹”概念,即每种污染源都有其唯一对应的水质指纹,以此进行污染排放源的识别。利用该技术监管企业排污,能准确监测到水质异常并发出预警,快速定位到嫌疑排污企业,从而可从源头解决污染问题,有效提升水环境监管工作效率。利用水质指纹识别技术,不仅可以识别企业超标排放和暗管偷排,而且可以进行污染路径溯源。案例研究表明,这项技术在水污染监管中发挥了重要作用。     

民航事故征候的关联度分析和灰色模型预测

民航事故征候的分析和预测是民航安全研究的重要内容,其目的是掌握民航事故征候影响因素的影响程度和未来发展状况,以此提出相应的安全措施,减少民航事故.通过对民航事故征候及其影响因子作灰色关联度分析,发现机组失误是关键因子,其后依次为总飞行时间、机械原因和天气原因;运用灰色模型对现有2001-2004年机组失误导致的事故征候的实测统计数据进行分析,预测出2005-2009年机组失误导致的事故征候次数分别为37、44、52、61和73;经过残差、后验差等检验分析,发现该模型精度较高,效果较理想.预测的趋势指示出机组失误导致的事故征候随时间的推移在增加.所以,在以后的航空安全管理工作中要着重加强机组管理,有效的预防和矫正机组行为失误,从而达到减少事故征候的目的.     

传热子模型对火灾网络模型的求解精度与速度的影响研究

分析半无限大物体的传热过程,提出线性化的传热计算方法并编制了计算子程序,将子程序嵌入传热子模型为有限厚墙体的《高层建筑火灾烟流运动特性预测软件》,利用实例分析比较了两种传热计算方法对火灾网络模型求解精度和求解速度的影响。计算结果表明对3个节点的简单建筑,半无限大传热子模型与有限厚模型的室温计算最大偏差不超过5%,而计算机耗时约减少了1/3。该研究的结论对《高层建筑火灾烟流运动特性预测软件》的进一步完善和成熟及其市场化具有重要的推动作用。     

The ethics of Google Earth: crossing thresholds from spatial data to landscape visualisation

‘Virtual globe’ software systems such as Google Earth are growing rapidly in popularity as a way to visualise and share 3D environmental data. Scientists and environmental professionals, many of whom are new to 3D modeling and visual communications, are beginning routinely to use such techniques in their work. While the appeal of these techniques is evident, with unprecedented opportunities for public access to data and collaborative engagement over the web, are there nonetheless risks in their widespread usage when applied in areas of the public interest such as planning and policy-making?