氢氧同位素测试分析的记忆效应及标定研究

以基于离轴积分腔输出光谱(OA-ICOS)原理的液态水同位素分析仪为例,通过开展记忆效应分析实验和标定方法分析实验,分析了氢氧同位素测试分析中的记忆效应表现特征,讨论了记忆效应对测试结果的影响程度,探讨了记忆效应标定方法。研究结果表明:采用常规运行方法进行氢同位素测试分析时,记忆效应是明显存在的,而进行氧同位素测试分析时,记忆效应表现并不明显;采用常规运行方法进行氢、氧同位素测试分析,基本可以达到液态水同位素分析仪的保证精度;测针次数的增加,对于提高氢、氧同位素的测试分析精度具有有效作用;选择与待测样品δ值最为相近的3个标样进行测试分析和标定处理工作,可达到提高测试效率、节省测试成本、提高测试精度的目的。     

基于状态空间法的SMA-复合支座隔震结构分析

研究了SMA(shape memory alloy)绞线-叠层橡胶复合支座的工作原理,将结构控制理论中的结构状态空间法应用到该复合支座隔震结构的数值模拟分析中。建立了普通框架、安装叠层橡胶支座和安装SMA复合支座框架的结构状态方程,应用SIMULINK工具箱建立结构仿真模型,得出不同条件下框架结构的时程反应曲线。通过对比分析可以看出SMA-复合支座能很好地改变结构的隔震效果,应用状态空间法进行SMA-复合支座隔震结构的数值模拟分析简单准确。     

A FELT GEOGRAPHY*

In this article I revisit a literary‐audio work I created in collaboration with a Vancouver composer for Intersections, a new music series organized by the Western Front in Vancouver, Canada. We spliced together recorded interview material with composed music to craft a site‐specific acoustic landscape. This work is presented as a site in which to explore creative, experimental ways of restaging memory and of bringing experiential landscapes more fully to life, immersing public audiences in the felt histories of the city.     

Identifying Nonstationarity in Turbulence Series

Because of rapid forcing by varying cloud and sky conditions, turbulence time series collected in the atmospheric surface layer over land may often be nonstationary. The meteorological community, however, has no consensus definition of what nonstationarity is and, thus, no consensus method for how to identify it. This study, therefore, adopts definitions for first-order and second-order stationarity taken from the time series analysis literature and implements new analysis techniques and probabilistic tests to quantify first-order and second-order nonstationarity. First-order nonstationarity manifests as a change in the series mean; second-order nonstationarity, as a change in the variance. The analysis identifies nonstationarity in surface-level turbulent temperature and water vapour series collected during two sample days with solar forcing influenced by cirrus and cirrostratus clouds, but that nonstationarity is not as severe as expected despite the rapid thermal forcing by these clouds. On the other hand, even with negligible cloud forcing, both sample days exhibited severe nonstationarity at night.     

临沂市河东区集体建设用地流转探讨

集体建设用地流转是促进土地节约集约利用,统筹城乡发展的有效途径。该文根据河东区集体建设用地的现状,分析了影响集体建设用地流转的主要原因,并针对实际情况提出确权登记、建立城乡统一的交易市场、完善流转程序、规范流转收益等破解集体建设用地流转难题的对策和建议。     

Return migration and the reiteration of gender norms in water management politics: Insights from a Chinese village

Recent work on return migration in China suggests return migrants bring with them new knowledge, skills, and potentially beneficial relationships accumulated during their sojourns, enabling them to introduce new forms of leadership and community action. Social remittances of this kind could be read as carrying the potential to enhance collective action in support of sustainable local natural resource-based livelihoods. This study of the links between return migration, leadership and collective action in water management sounds a more cautionary note, demonstrating that home communities may respond to return migrants in ways that repeatedly mark and reiterate gender and kinship norms, reiterating gender, generational and clan-based social hierarchies. The paper draws on and contributes to recent feminist political ecology approaches to show how migrant returnees’ ’social remittances’ translate into leadership in collective action in a rural Chinese village in ways that reinforce existing gender hierarchies and social positions within the community, thus questioning the extent to which any influx of new ideas, relationships and practices acquired from migrant experiences necessarily destabilizes power and authority in the village in any meaningful way.     

瑞利参数在海浪波高机器学习预测中的应用

海浪直接影响海上活动和航行安全,同时也蕴藏着巨大的可再生能源,对海浪核心参数之一波高预测至关重要。基于2015年7月～2022年6月山东小麦岛(36°N,120.6°E)站点实测的波高数据,利用反向传播神经网络(back-propagation neural network,BPNN)、长短记忆网络(long short-term memory, LSTM)和支持向量机回归(support vector regression, SVR)三种机器学习模型对波高进行预测,并分析了瑞利参数的引入对预测结果的影响。结果显示,模型输入项引入瑞利参数后,对1 h和6 h波高预测提升效果有限,预测值与测试集的相关性提升不超过0.02,均方根误差的降低不超过0.01 m;在12h和24h的预测中,BPNN和LSTM模型预测结果相关性提升0.03～0.07,均方根误差降低0.02～0.03m,而SVR模型预测结果变化不显著。说明瑞利参数有助改善BPNN和LSTM模型中长期海浪预报。此外,特征扰动方法(机器学习中特征重要性的计算方法之一)验证了瑞利参数在波高预测中的重要性,瑞利参数的引入为波高的机器学习预...     

Interpreting the Civil Rights Movement: Place,Memory, and Conflict

Produced over the past decade, monuments and museums dedicated to the Civil Rights movement of the 1950s and 1960s have desegregated America's memorial landscape. Tracing a broad arc across the US South, the material elements of this landscape — historic markers, monuments, parks, registered buildings, and museums — present a distinct challenge to representations of an elite, white American past. This challenge, however, is offered in a distinctly gendered manner, inasmuch as the role of women in organizing and leading the movement is obscured. Further, the historical narratives concretized at these sites are mediated by conventions associated with civil rights historiography and the tourism development industry. The result is a complex, sometimes ironic landscape. Via the narratives they embed and the crowds they attract, these landscapes are co‐constitutive with contemporary politics of representing the past in the United States. This paper offers an overview of current memorial practices and representations of the Civil Rights movement found at the country's major memorial landscapes.     

旅游开发影响下民族社区文化记忆的代际传承——以西安回民街历史文化街区为例

在旅游开发背景下,目的地社区文化记忆的代际延续与传承对居民的地方认同具有重要意义.本文借助文化记忆媒介的理论框架,依托23位本地居民的深度访谈,探究旅游影响下代际间记忆传承的时空媒介信息与延续性要素.研究发现:①在旅游开发影响下,虽然新一代与老一代居民在文化记忆空间的认知与表述上存在差异性,但记忆媒介在旅游发展中的保留...