土地可持续利用评价指标体系与方法研究概述

概述了土地可持续利用评价研究的历史,归纳和总结了土地可持续利用评价研究已取得的成果,指出了土地可持续利用评价指标体系与方法研究中存在的问题与不足。     

基于缺口应力法的焊接接头多轴疲劳分析

鉴于当前焊接接头疲劳评估曲线只适用于单轴加载情况,基于缺口应力法对焊接接头进行了多轴疲劳分析。通过联合焊接接头的多轴疲劳试验名义应力数据和有限元法所计算的缺口应力集中系数,获得了5种焊接接头的各向缺口应力;根据Von Mises、ⅡW和EESH 3种多轴疲劳准则计算出等效缺口应力并将其统一在同一坐标系统下;最后采用最小二乘法拟合出适用于多轴疲劳评估的缺口寿命曲线。与ⅡW标准推荐的单轴曲线相比,这些多轴缺口疲劳曲线具有更低的倾斜度和更高的疲劳等级,即多轴加载时明显降低了10³~10⁶次中周范围内的疲劳强度值,而对10⁶~10⁷次高周疲劳范围的影响则相对有限。     

基于摩尔库仑准则的膨胀土弹塑性本构模型及其数值实现

膨胀土的应力应变关系与含水量的变化有关,通过室内试验对膨胀土的变形、强度以及膨胀参数与含水量之间的关系进行研究,以湿度应力场理论为基础,提出了一个具有工程实用价值的基于摩尔库仑准则的膨胀土弹塑性本构模型。依据FLAC3D数值模拟软件所提供的二次开发程序,给出了该膨胀土弹塑性本构模型二次开发程序过程的基本原理以及模型的程序框图。结合渗流软件计算的湿度场分布,进行膨胀土基坑边坡实例验算,验证了该本构模型的正确性。     

峨眉山野生药食两用蔬菜资源初步调查

峨眉山野生药食两用蔬菜资源十分丰富,经实地考察、标本收集、鉴定、整理,初步确定有30科54属85种。其中真菌类5科7属10种,蕨类2科2属2种,裸子类1科1属1种,被子类22科44属 72种。     

西南干暖河谷土壤细沟可蚀性垂直地带性差异

为探究以干暖河谷为基带的西南山地土壤细沟可蚀性垂直地带性差异,选择该区不同垂直带典型土地利用类型(林草地和耕地)下不同土壤类型(红壤、黄壤、棕壤和暗棕壤)为研究对象,利用室内“V”形细沟模拟装置,分别进行6种流量(150,300,450,600,750,900mL/min)和3种水文状态(排水状态、饱和状态和渗流状态)的模拟冲刷试验。结果表明:(1)该区土壤颗粒组成无明显的垂直地带性,林草地的砂粒含量偏高,各土壤的颗粒含量差异在9%以内,所有土壤均为粉质壤土,但有机质差异较大,且随着海拔增加而增加;(2)土壤的细沟可蚀性具有明显的垂直地带性,随海拔升高,林草地土壤可蚀性Kr值逐渐减小,相比于红壤,暗棕壤的Kr值减小幅度平均为47.74%,耕地土壤中黄壤略大于红壤,可能与人为活动强度和土壤熟化程度有关;(3)不同土地利用方式下,林草地土壤Kr值显著大于耕地土壤Kr值,平均增幅为22.63%,这可能与有机质促进土壤抗侵蚀性能的提高有关;(4)不同近地表水文状态下,土壤的细沟可蚀性表现为渗流状态>饱和状态>排水状态,表明随着近地表水文状态变化,尤其是垂直水力梯度的增加会显著导致土壤的细沟可蚀性增大;试验还发现,土壤的临界剪切力仅在不同的水文状态下具有渗流状态>饱和状态>排水状态的规律性,而在不同海拔和土地利用类型之间没有明显的规律性。     

Modeling black carbon removal by city trees: Implications for urban forest planning

Urban forests provide multiple ecosystem services, including particulate matter (PM) air pollution removal. While previous studies have assessed relationships between atmospheric PM concentrations and urban land use and land cover, few studies have modeled PM removal by trees in relation to urban form (e.g., topography, land use, land cover, and proximity to emission sources). Particulate matter is a mixture of particles, including black carbon (BC), a byproduct of incomplete fossil fuel and biomass combustion with strong warming potential and linked to adverse health outcomes. We coupled empirical BC deposition data, collected from urban trees in Denton, Texas, with 226 urban form variables to generate land use regression models of annual and seasonal BC removal. Annual and seasonal models revealed emission source proxies, terrain exposure towards emission sources, and topographic exposure as influential to BC removal by trees. Regression equations were applied at one-meter resolution to estimate the BC removal potential of tree planting across the city. The resultant maps, which show regions of probable high and low BC removal by trees, can be used by arborists, urban foresters, landscape architects, and urban planners to inform urban forest design, planning, and decision-making.     

Revised Contemplative Landscape Model (CLM): A reliable and valid evaluation tool for mental health-promoting urban green spaces

Due to rapid urbanization and an increase in mental health issues in urban populations, urban green spaces (UGS) design needs to be optimized to meet mental health and well-being promotion goals. However, existing frameworks and tools that aim to address this pressing need are often not adequately validated against health measures. The Contemplative Landscape Model (CLM), developed in 2016, is the first instrument that measures the quality of UGS and informs landscape design with regard to the mental health and well-being of people passively exposed to them. Recent studies with this tool and developments in UGS literature prompted the development and validation of a revised version of CLM presented here. The reliability and validity of CLM were tested with a panel of independent experts and showed better reliability/internal consistency (ω = .893; α = .890) than the original CLM. This time, validity was tested in two ways: (1) against neuropsychological data (electroencephalogram, EEG, and self-reported valence and arousal ratings), acquired during passive exposure to UGS scenes and (2) through factor analysis of experts’ UGS assessments. Validity testing showed that (1) CLM predicts brain activity patterns associated with mindfulness, relaxation, and positive mood, and (2) contemplativeness of landscapes is a valid construct undergird by two parallel factors both predicting beneficial EEG responses. In conclusion, CLM is an effective and robust instrument for assessing the visual quality of UGS predictive of mental health and well-being benefits in urban residents.     

Increasing strawberry shelf-life with carvacrol and methyl cinnamate antimicrobial vapors released from edible films

The effect of carvacrol and methyl cinnamate vapors incorporated into strawberry puree edible films on the postharvest quality of strawberry fruit (Fragaria × ananassa) was investigated. Fresh strawberries were packed in clamshells and kept at 10 °C for 10 days with 90% RH. Strawberry puree edible films, applied in the clamshell, served as carriers for the controlled release of natural antimicrobial compounds without direct contact with the fruit. Changes in weight loss, visible decay, firmness, surface color, total soluble solids content, total soluble phenolics content and antioxidant capacity of strawberries during storage were evaluated. A significant delay and reduction in the severity of visible decay was observed in fruit exposed to antimicrobial vapors. Carvacrol and methyl cinnamate vapors released from the films helped to maintain firmness and brightness of strawberries as compare to the untreated strawberries. The natural antimicrobial vapors also increased the total soluble phenolics content and antioxidant activity of fruit at the end of the storage period.     

Drone remote sensing in urban forest management: A case study

We applied drone remote sensing to identify relationships between key forest health indicators collected in the field and four Vegetative Indices (VI) to improve conservation management of urban forests. Key indicators of urban forest health revealed several areas of conservation concern including a majority of overstory trees in moderate to severe decline, canopy gaps, anthropogenic dumping, vines overtaking the forest canopy, and invasion by non-native plant species. We found plot-level vegetation index (VI) values of NDVI, NDRE, GNDVI, and GRVI calculated from drone imagery are significantly related to the impact of several of these ecological concerns as well as metrics of forest composition and equitability. Despite the small number of plots, too few to provide a general predictive framework, these findings indicate a substantial potential for drone remote sensing as a low-cost, efficient tool for urban forest management. We discuss how our findings can advance urban forest management and discuss challenges and opportunities for future drone VI research in urban natural areas.     

How perceived sensory dimensions of urban green spaces affect cultural ecosystem benefits: A study on Haizhu Wetland Park,China

Research exploring the relationship between human well-being and ecosystem functions by assessing cultural ecosystem benefits (CEBs) is a crucial and emerging field. However, quantifying CEB is challenging due to the lack of a uniform measurement scale. In addition, it is crucial to understand the factors that influence CEBs to enhance ecosystem functions and contribute to human well-being. While physical landscape features have been investigated, there is limited evidence supporting the link between perception-based landscape features and CEBs. Therefore, this study aimed to develop a CEBs measurement scale and investigate the impact of perceived sensory dimensions (PSDs) of urban green spaces (UGSs) on CEBs. We conducted a Public Participation GIS-survey (PPGIS) at Guangzhou National Haizhu Wetland Park. 1473 participants took part in our study and evaluated the CEBs provided by urban green spaces (UGSs). Using SPSS statistics and ArcMap tools, we found that PSDs of UGSs are significantly associated with CEB. Additionally, we confirmed that different levels within a PSD influence the levels of CEBs gained from UGSs. Our results indicate that creating serene, open, and natural UGSs is more effective than incorporating numerous cultural elements. In conclusion, this study introduces PSDs into the framework of CEB, which landscape architects can use to shape the specific environmental characteristics of UGSs and provide the CEBs required to support the well-being of urban populations.