综合预应力与陀螺效应的TLJ500土工离心机模态分析

目的 分析获得离心机运转时各综合效应对其模态频率的影响.方法 从理论上推导结构在无离心场时,仅考虑预应力刚化效应和仅考虑旋转软化效应与综合考虑各效应时结构固有频率之间的关系.建立TLJ500土工离心机静止状态及运转状态的有限元模型,并根据TLJ500静止状态的模态试验结果对有限元模型中主轴轴承部位的材料参数进行修正识别,获得可信度更高的模型.再将修正识别得到的主轴轴承参数代入离心机运转状态的有限元模型,开展离心机运转状态的模态分析,结合理论分析结果,计算得到综合考虑预应力刚化效应与旋转软化效应时离心机关心模态频率的结果.结果 运转状态TLJ500离心机关心模态频率计算结果与试验结果比较一致.结论 仿真结果验证了文中方法的可行性,为离心机临界转速设计提供了一种可信的数值模拟预测方法.     

2016-2018年西宁市颗粒物来源及输送差异分析

利用HYSPLIT模式计算了2016—2018年西宁市逐日72 h气团后向轨迹,采用聚类分析方法,结合同期颗粒物PM₁₀和PM_2.5质量浓度数据,分析逐年和3年平均西宁市颗粒物输送特征及差异,运用潜在源贡献因子分析法（PSCF）和浓度权重轨迹分析法（CWT）对影响西宁市PM₁₀和PM_2.5质量浓度的污染潜在源区及不同潜在源区贡献进行了分析.结果表明,2016—2018年,西宁市颗粒物最主要输送路径源自青海北部的聚类2、甘肃中部的聚类6和甘肃东部的聚类8,占同期总轨迹比例分别为28.1%、27.4%和27.5%;3年平均则源自青海北经青海东折回西宁的聚类2,占比45.3%.最主要输送路径对应颗粒物质量浓度最低,输送距离较短、垂直高度较低、气团移速较慢;影响气团由西北向偏东转变,3年平均则以西北气团为主.2018年源自甘肃经青海东至西宁的短距离输送处于突出地位,所含轨迹占总轨迹的比例高达49.6%.PM₁₀和PM_2.5主要输送路径和污染路径由较长距离向较短距离过渡,较长距离输送路径出现比例逐年较小.PM_2.5/PM₁₀小于0.3时,主要输送路径与PM₁₀污染轨迹有很好的对应关系;PM_2.5/PM₁₀大于0.6时,主要输送路径与PM_2.5污染轨迹有较好的对应关系.PSCF和CWT分析发现,影响西宁市颗粒物质量浓度的主要污染潜在源区分布在新疆南部和青海北部,对PM₁₀质量浓度贡献大于100 μg·m^-3,对PM_2.5质量浓度贡献大于45 μg·m^-3.潜在源区分布年变化差异明显,2016年最广,2018年最小.印度北部主要贡献源区虽分布范围逐年减小,但在2017年局部贡献增大,对PM₁₀贡献超250 μg·m^-3,对PM_2.5贡献超60 μg·m^-3.主要贡献区周边区域及西宁至兰州一带为中等贡献源区,对PM₁₀贡献为50~100 μg·m^-3,对PM_2.5贡献为15~45 μg·m^-3.     

抚河南昌段重金属空间分布特征及来源分析

为分析抚河南昌段流域水体中重金属空间分布特征及可能来源,2019年08月在抚河南昌段共采集了23个地表水样及8个地下水样,对水体中的重金属V、Mn、Ba、Fe、Sr、Zn及类金属元素As进行了测定.结果表明,水体中不同重金属空间分布特征总体趋势一致,即中下游地区高于上游地区,污染特征空间差异性为中等及以上.地表水中V、Fe、Mn的平均浓度超过《地表水环境质量标准》（GB3838-2002）集中式生活饮用水特定项目标准限值;地下水中类金属元素As平均浓度超过《地下水质量标准》（GBT14848-2017）Ⅲ类水质标准.多元统计分析表明Sr、Ba、Mn可能主要来源于人类生产、生活污染物的排放,Fe、V、Zn可能主要来源于农业渔业及交通污染,类金属元素As主要来源于沿岸及河流底部淤泥及岩石碎屑.     

昆明市污水排水系统产甲烷规律的模拟实验研究

通过对昆明市餐饮和居民生活污水厌氧模拟实验研究,初步探讨生活污水中CH4的产生规律,实验结果表明,在自然条件下,餐饮和居民生活污水中产生的甲烷浓度最大值分别为1.63 mg/L和3.82 mg/L。并且将COD、硫酸盐、硫化物、TN的浓度变化与甲烷浓度变化进行Pearson简单相关性分析,结果表明,1/COD、COD/硫酸盐和1/TN与甲烷在置信度为0.01时极显著相关,硫化物与甲烷在置信度为0.05时不相关;COD、硫酸盐和TN浓度的变化对生活污水中甲烷的产生起关键性作用。对居民生活污水中甲烷产生规律进行温度和pH控制分析研究,实验结果表明,生活污水在25~30℃时,24 h内甲烷产生量最大值为8.6494 mg/L,明显大于其他温度段的甲烷产生量;在pH为7~8之间时,甲烷的产生量在24 h内达到的最大值为3.0477 mg/L,明显高于其他pH控制段的甲烷产生量。     

拉萨市近49年气温变化特征研究

2019年6月24日拉萨市出现了30.8℃的高温,创历史新高.为了更好的了解拉萨市气候变暖的机理以及评估该区域未来气候的变化状况,本文基于拉萨市自动气象站近49年的观测数据,采用线性趋势法、Mann-Kendall (M-K)突变检验、小波分析、R/S分析等方法深入研究了多时间尺度上气温的时空演变特征.结果 显示:(a...     

国家环境经济政策进展评估报告2022

本年度报告采取实地调研法和政策分析法,针对2022年我国环境经济政策实践开展系统评估,总体认为2022年环境经济政策体系建设不断完善,环境经济政策改革与创新工作取得积极进展,有力推动了高质量发展动力转换、绿色发展结构转型,在生态文明与美丽中国建设中发挥了重要作用。未来需要进一步优化环境经济政策,建立健全一套更加科学合理、公平长效、激发活力的环境经济政策体系,充分支撑环境质量改善与高质量发展。     

“Science is Everywhere,but No One Knows It”: Assessing the Cultural Distance to Science of Rural South African Publics

ABSTRACT

In science communication, a prerequisite for reaching different parts of a society is to find out how these publics experience and interpret science. Since rural South African publics are perceived to exhibit a large cultural distance to science, the present exploratory study aimed to know in more detail how rural South Africans perceive and understand science in their local and social contexts. Theoretical notions on cultural distance and the methodological approach of segmentation studies were considered. Semi-structured interviews with rural South Africans were carried out in four towns (n?=?52) that differ with respect to having a large scientific installation in their vicinity, or not. Sensitively comparing local and social contexts helped identifying three different publics who differed regarding their perceptions of science; however, the large scientific installations only made a difference in perceptions for those publics who were generally less exposed to and less knowledgeable about science.     

近15a江苏省水源涵养功能时空变化与影响因素探析

定量评估生态系统服务功能是合理利用自然资源、促进人地关系与可持续发展的基础。以江苏省为研究区,基于InVEST模型产水模块,定量分析了江苏省2000~2015年产水功能和水源涵养功能的时空变化特征,并采用回归分析和主成分分析法评估了水源涵养功能与社会经济要素之间的关系。结果表明：（1）江苏省多年平均产水量为571×108 m³/a,水源涵养总量78.39×108 m³/a;（2）2000~2010年江苏省水源涵养功能呈下降趋势,2010~2015年有所回升,考虑到降水因素,江苏省实际水源涵养功能持续降低;（3）土地利用变化使15a来水源涵养功能下降15.2×108 m³,降低幅度为16.9%;（4）流域尺度上水源涵养功能与江苏社会经济因素相关关系不显著。研究结果可以为土地利用优化、流域水资源管理提供科学参考和支持。     

Community participation in cultural heritage and environmental policy formulation in Botswana

Cultural heritage does not have direct economic benefits. However, if properly managed it can stimulate social cohesions, improving the environment and have beneficial economic spin offs for the local communities. This paper discusses the role of communities in the formulation of the policies concerning their local environment. It argues that community engagement by policy makers is important in giving legitimacy and ownership of the policies. Furthermore, this paper discusses the potential of cultural heritage in diversifying the economy in Botswana. This paper recommends for the re-assessment of the relationship between the state and local communities which is critical in resuscitating the seemingly ailing community business organizations. In conclusion, it argues for the sustainable management of cultural heritage as a social and economic resource in the next 50 years of Botswana’s independence.     

Food for Thought: Audience Engagement with Sustainability Messages in Branded Content

Branded platforms are a growing “gray-zone” of marketing and media messages, in which corporations and news journalists partner to create content that supports strategic corporate goals while aligning with a publication’s scope of editorial coverage. As corporations are key influencers of and contributors to environmental communication, this trend has the potential to change environmental dialogue. In this article, we closely examine messages about food and sustainability, created in partnership by Chipotle Mexican Grill and the Huffington Post news site. We illustrate how use of a branded platform expanded the scope of environmental topics, issues, and frames that Chipotle addresses, how frames identified here connect to frames in coverage of science-related issues, as identified by other scholars, and discuss how branded platforms allow corporations to draw attention to polarizing environmental issues while protecting stakeholder relationships and brand reputation.