基于数量关系研究铝合金船体点蚀对拉伸性能的影响

目的 通过点蚀与拉伸性能的数量关系,为5083铝合金船体不同腐蚀状态板材相应修换要求的提出提供数据支持.方法 对服役10 a的某型艇船体5083铝合金板,进行点蚀特征参数统计,并测试其拉伸性能.对四个点蚀参数与拉伸强度损失的关系进行拟合回归分析及相关性分析,找出相应的数量关系.结果 由拟合回归分析可知,最大点蚀深度数据样本与拟合曲线较契合,与拉伸性能的相关度最高.另外得出了点蚀参数与拉伸强度损失之间的函数关系,可以估计相应的指标.由相关性分析可知,最大点蚀深度与拉伸强度的相关系数大于0.9,属于强相关.自变量中,最大点蚀深度和平均点蚀深度这两个指标出现一定程度的冗余.结论 点蚀特征及拉伸性能数量关系的研究可以为铝合金船体板的拉伸性能进行相关预测,并可为铝合金船体板的耐蚀寿命研究提供依据.     

城市化与城市生态化是一个过程的两个方面

城市化必须同时伴随着城市生态化,或者说城市化和城市生态化是一个过程的两个方面而不是两个过程。工业革命以来,世界的城市化进程已经成为一个不争的事实,然而19世纪前城市化过程往往是只注重城市化而忽视生态化,甚至以牺牲生态来实现城市化,以致城市变成了生态的对立物。严峻的城市环境迫使人们反思以往城市建设模式和理念,上世纪70年代生态城市理念的提出,使人们有可能从城市生态化的视角来审视城市化,把城市化和城市生态化统一起来。这具有极大的理论和实践意义。     

Prediction of DOM removal of low specific UV absorbance surface waters using HPSEC combined with peak fitting

High performance size exclusion chromatography (HPSEC) is used in water quality research primarily to determine the molecular weight distribution of the dissolved organic matter (DOM), but by applying peak fitting to the chromatogram, this technique can also be used as a tool to model and predict DOM removal. Six low specific UV absorbance (SUVA) source waters were treated using coagulation with alum and both the source and treated water samples were analysed using HPSEC. By comparing the molecular weight profiles of the source and treated waters, it was established that several DOM components were not effectively removed by alum coagulation even after high dosage alum treatment. A peak-fitting technique was applied based on the concept of linking the character (molecular weight profile) of the recalcitrant organics in the treated water with those of the source water. This was then applied to predict DOM treatability by determining the areas of the peaks which were assigned to removable organics from the source water molecular weight profile after peak fitting, and this technique quantified the removable and non-removable organics. The prediction was compared with the actual dissolved organic carbon (DOC) removal determined from jar testing and showed good agreement, with variance between 2% and 10%. This confirmed that this prediction approach, which was originally developed for high SUVA waters, can also be applied successfully to predict DOC removal in low SUVA waters.     

区域电离层GPS双频改正模型研究

通过电离层延迟改正模型推导及对电离层延迟改正的主要因素的阐述,提出曲面拟合、距离加权和多面函数法3种区域电离层改正拟合模型,得出一定区域内的每个测站用双频改正模型求出电离层改正值,然后用曲面拟合法对整个区域进行拟合,得出区域改正模型。     

Data-directed modelling of Daphnia dynamics in a long-term micro-ecosystem experiment

The micro-ecosystem under consideration consists of three compartments forming a closed chain in which water circulates. Three trophic levels are represented in different compartments: autotrophs (algae, mainly Chlorella vulgaris), herbivores (Daphnia magna) and microbial decomposers. From a 20 years experiment with this system, data has been selected for this study. The dynamics of algae and Daphnia magna in only one of the compartments were modeled by different systems of differential and difference equations. We describe the successive steps in the process of model development, and the fitting of parameters using a Nelder-Mead simplex calibration method. Identification problems were overcome by taking values for physiological parameters in agreement with the literature. It turned out that a logistic type of model gives the best result for the structured Daphnia population because of the set up of the experiment: algae grow and reproduce in the upstream compartment. For this reason well-known plant–herbivore models did not comply with the data. The results of the parameter estimation procedure are discussed. The estimated grazing rate by Daphnia was smaller than expected. Possibly the Daphnia fed also on detritus and decomposing algae which were not measured.     

Optimization of ecosystem model parameters using spatio-temporal soil moisture information

Parameters in process-based terrestrial ecosystem models are often nonlinearly related to the water flux to the atmosphere, and they also change temporally and spatially. Therefore, for estimating soil moisture, process-based terrestrial ecosystem models inevitably need to specify spatially and temporally variant model parameters. This study presents a two-stage data assimilation scheme (TSDA) to spatially and temporally optimize some key parameters of an ecosystem model which are closely related to soil moisture. At the first stage, a simplified ecosystem model, namely the Boreal Ecosystem Productivity Simulator (BEPS), is used to obtain the prior estimation of daily soil moisture. After the spatial distribution of 0–10 cm surface soil moisture is derived from remote sensing, an Ensemble Kalman Filter is used to minimize the difference between the remote sensing model results, through optimizing some model parameters spatially. At the second stage, BEPS is reinitialized using the optimized parameters to provide the updated model predictions of daily soil moisture. TSDA has been applied to an arid and semi-arid area of northwest China, and the performance of the model for estimating daily 0–10 cm soil moisture after parameter optimization was validated using field measurements. Results indicate that the TSDA developed in this study is robust and efficient in both temporal and spatial model parameter optimization. After performing the optimization, the correlation (r²) between model-predicted 0–10 cm soil moisture and field measurement increased from 0.66 to 0.75. It is demonstrated that spatial and temporal optimization of ecosystem model parameters can not only improve the model prediction of daily soil moisture but also help to understand the spatial and temporal variation of some key parameters in an ecosystem model and the corresponding ecological mechanisms controlling the variation.     

天津臭氧浓度与气象因素的相关性及其预测方法

气象因素在影响夏季臭氧浓度水平和变化特征方面扮演着重要作用.通过对2008年夏季天津地面臭氧体积浓度和气象因素的相关分析,揭示高浓度臭氧发生时的典型气象特征,并初步建立了预测地面臭氧浓度的气象学方法.结果表明:影响臭氧浓度的主要气象因素是气温、相对湿度和风速、风向,当14时气温大于30℃,相对湿度低于60%,风向为偏西或偏南时,高浓度臭氧的发生概率较高.采用14时气温、相对湿度和风速等气象参数拟合臭氧体积浓度,效果良好.     

经济结构、增长方式与环境污染的内在关联研究——基于时变参数向量自回归模型的实证分析

基于对数平均迪氏指数（LMDI）方法分解影响环境污染的经济因素,利用时变参数向量自回归（TVP-VAR）模型研究了各因素在不同时点、不同提前期对污染物排放的动态冲击特征.结果表明,技术进步具有提高企业生产率以及提升企业产品清洁度的双重效果,产生的创新补偿效应降低了污染排放.我国以煤炭为主的能源消费结构和煤炭消耗产生不容易累积的烟煤型污染物,使得能源结构引致的污染效应在当期最为明显,且持续期较短.能源利用效率的大幅提升有效降低了污染物排放,同时也呈现了一定的反弹效应.产业结构对环境污染的影响逐渐增强、经济规模扩大对于环境污染的冲击具有较强的持续性.合理控制结构因素和规模因素对污染物排放的影响,成为了降低污染水平的重要环节.     

腐朽坑木与煤混合物升温氧化特性研究

为研究煤层及腐朽坑木着火特性,采集巷道内腐朽坑木与煤样并进行混合,对其混合物进行燃点测定和程序升温实验;通过对不同煤木混合物在升温过程中产生气体的规律性进行分析,优选出混合物产生的单一气体指标及复合指标.研究结果表明:随朽木在混合物中的比例上升,混合物燃点呈下降趋势,且CO,C2 H4等指标气体出现更早,CO产生量更大...     

区间化AIS数据驱动的抵泊过程多维控制模型

为提高船舶靠泊安全,对接智能靠泊,实现船舶抵泊过程中的姿态控制,运用切比雪夫拟合法、95％置信度区间法、最小二乘法及上述组合方法的2次拟合等优化策略,拟合区间化船舶自动识别系统(AIS)数据中速度、航向、艏向和船位等靠泊控制参数,构建区间化AIS数据驱动的多维抵泊姿态控制模型,并采用某轮靠泊南京龙潭港一年的AIS数据测...