基于高光谱指数的水稻砷污染胁迫多重判别模型

水稻中过量砷(As)能够影响叶片中叶绿素含量、水分含量以及细胞内部结构,进而改变水稻在光谱上的特征表现.以表征叶绿素、水分含量、细胞结构的NDVI、NDWI、SIPI等9种高光谱指数和实测水稻叶片砷含量数据为基础,利用相关分析、主成分分析和独立变量分析方法,获得诊断指标对水稻砷污染胁迫进行多重光谱判别.结果表明,表征不同生理参数的高光谱指数PSNDa、fWBI、SIPI与水稻叶片砷含量高度相关,可作为砷污染单级光谱诊断参数;主成分因子F1、F2和独立变量因子ICA1、ICA2对水稻砷污染胁迫具有特殊反应,分别作为水稻砷污染胁迫的主成分诊断指标和独立分量诊断指标.综合上述3类诊断参数,构建水稻砷污染胁迫多重判别空间体系即光谱指数诊断空间(PSNDa-fWBI、PSNDa-SIPI、fWBI-SIPI)、主成分诊断空间(F1-F2)和独立变量诊断空间(ICA1-ICA2),从不同层面上综合诊断了实验区水稻砷污染胁迫情况,其中以表征叶绿素和细胞结构的光谱指数空间PSNDa-SIPI与主成分空间F1-F2诊断效果为最佳.     

航天动力学环境的最新进展与技术展望

总结了近年来航天动力学分析、试验方面的最新成果。按照航天飞行器寿命期不同阶段的特点,对动力学试验与理论建模、分析预示、试验技术、测量方法,特别是地面气候复合以及高速飞行热结构动力学分析与试验方面的工作进行归纳,并指出存在的不足,以及未来发展的方向。通过工程研制中的分析与数据积累修正,在建模分析预示、条件制定以及测量技术等方面取得显著成果,但由于飞行器复杂,在准确精细预示方法、热结构预示与试验技术方面以及气候复合状态下的分析与试验方面尚需大量研究。应坚持理论与试验、工程研制与研究相结合的方式,不断完善持续改进,实现动力学精细化预示与天地一致性试验。     

随机过程“各态历经”理论应用于环境噪声监测优化布点

本文尝试应用随机过程“各态历经”理论，在大、中、小多个样本中研究城市环境噪声监测的时—空相关性，找出“定点测量法”与“网格测量法”的内在联系，探讨以“定点测量法”取代“网格测量法”进行城市区域环境噪声普查的可行性，从而实现环境噪声监测优化布点及为实现城市环境噪声自动监测布点提供技术依据     

基于三生空间生态服务供给和需求的国土空间规划效益评价研究

国土空间规划是统筹区域资源空间配置、开发管理和布局优化的总体方案,在引领区域协调发展上具有重要意义。国土空间规划必然导致土地利用类型及布局的改变,从而引起经济、社会、生态环境等方面的供给与需求变化。本研究从三生空间耦合协调的角度,通过生态系统服务和人类福祉需求的供需关系,揭示三生空间的供需连接与耦合关系。本研究借助 InVEST模型和生态服务价值当量法对生态系统服务供给与需求进行定量分析,同时引入耦合协调度模型与相对发展度模型,通过对生态系统服务供需变化进行耦合协调类型分析,探究国土空间用地结构调整所产生的供需间的协调关系,并用耦合协调状况对国土空间规划效益进行评价。研究发现,在规划期内宜宾市翠屏区生态系统服务供需总体耦合协调度呈现减小态势。2020-2035年耦合协调度从 0.60降低到 0.59,相对发展度由 1.05减小至 1.01。生态系统服务总体供给盈余明显,但由于供需分布空间差异,城镇地区为主要的供给赤字区域。影响生态系统服务需求的主要因素为环境净化需求,城市化指标对生态系统服务供需相对发展度具有较为普遍的负面影响。     

管道燃气爆炸特性实验研究

管道是化工及油气储运系统的重要组成部分,却时常受燃烧爆炸事故的威胁,因此对管道中燃气燃烧爆炸特性与规律的研究就十分必要。以甲烷作为研究对象,采用压力传感器以及火焰传感器等对水平封闭管道内甲烷-空气预混燃烧爆炸进行了实验研究,通过大量实验来研究可燃气体爆炸压力与火焰及其传播变化规律。根据实验结果将超压以及气体燃烧的变化情况,对前驱冲击波与火焰面的相对时间及相对位置关系进行了分析。结果显示,管道中会产生前驱压力波,并超前火焰阵面甲烷气体在管道传播过程中,出现冲击波反压射、波叠加及反冲现象,压力的持续时间较火焰光信号持续时间长。所做的工作为油气受限空间中燃气燃烧爆炸特性与规律的进一步研究及工业防爆抑爆技术及工艺的实施、系统设计以及关键参数计算提供了理论依据。     

Relationships between Human Disturbance and Wildlife Land Use in Urban Habitat Fragments

Abstract: Habitat remnants in urbanized areas typically conserve biodiversity and serve the recreation and urban open‐space needs of human populations. Nevertheless, these goals can be in conflict if human activity negatively affects wildlife. Hence, when considering habitat remnants as conservation refuges it is crucial to understand how human activities and land uses affect wildlife use of those and adjacent areas. We used tracking data (animal tracks and den or bed sites) on 10 animal species and information on human activity and environmental factors associated with anthropogenic disturbance in 12 habitat fragments across San Diego County, California, to examine the relationships among habitat fragment characteristics, human activity, and wildlife presence. There were no significant correlations of species presence and abundance with percent plant cover for all species or with different land‐use intensities for all species, except the opossum (Didelphis virginiana), which preferred areas with intensive development. Woodrats (Neotoma spp.) and cougars (Puma concolor) were associated significantly and positively and significantly and negatively, respectively, with the presence and prominence of utilities. Woodrats were also negatively associated with the presence of horses. Raccoons (Procyon lotor) and coyotes (Canis latrans) were associated significantly and negatively and significantly and positively, respectively, with plant bulk and permanence. Cougars and gray foxes (Urocyon cinereoargenteus) were negatively associated with the presence of roads. Roadrunners (Geococcyx californianus) were positively associated with litter. The only species that had no significant correlations with any of the environmental variables were black‐tailed jackrabbits (Lepus californicus) and mule deer (Odocoileus hemionus). Bobcat tracks were observed more often than gray foxes in the study area and bobcats correlated significantly only with water availability, contrasting with results from other studies. Our results appear to indicate that maintenance of habitat fragments in urban areas is of conservation benefit to some animal species, despite human activity and disturbance, as long as the fragments are large.     

浅议生态城市建设的4个环节

阐述了生态城市理念的演化过程和生态城市的不同提法,针对生态城市建设中需要解决的诸多问题,提出了生态城市建设应主要抓好的4个环节:和谐是生态城市的核心,发展是生态城市的动力,绿色是生态城市的生命,文明是生态城市的精髓。     

The potential of statistical state space models in urban ozone forecasting

State space models for tropospheric urban ozone prediction are introduced and compared with linear regression models. The linear and non-linear state space models make accurate short-term predictions of the ozone dynamics. The average prediction error one hour in advance is 7 μg/m³ and increases logarithmically with time until it reaches 26 μg/m³ after 30 days. For a given sequence of solar radiation inputs, predictions converge exponentially with a time scale of 8 hours, so that the model is insensitive to perturbations of more than 150 μg/m³ O₃. The slow increase of the prediction error in addition to the uniqueness of the prediction are encouraging for applications of state space models in forecasting ozone levels when coupled with a model that predicts total radiation. Since a radiation prediction model will be more accurate during cloud-free conditions, in addition to the fact that the state space models perform better during the summer months, state space models are suitable for applications in sunny environments.     

采空区多孔介质空隙率与渗透特性三维空间动态分布模型*

为揭示采空区垮落后堆积体及上覆岩层空隙率与渗透率三维空间的动态分布规律,基于开采空间守恒理论,构建采空区的空隙率与渗透率三维空间动态分布模型。利用该模型,得出不同空间位置与不同开采结束时间下空隙率和渗透率分布图。结果表明:采空区垮落岩体的空隙率和渗透率在水平方向呈“凹”状分布,采空区两侧巷道附近空隙率和渗透率较大,中部较小;在垂直方向随着与底板距离的增大,空隙率和渗透率大幅度减小。该模型描述了采空区多孔介质空隙率与渗透特性三维空间分布随时间逐步压密实的过程,可为煤矿瓦斯预测与防治提供一定的借鉴和参考。     

室内准稳态压力火灾烟气沉降模型的改进和实验验证

对室内火灾及烟气的研究给消防工程领域带来了诸多益处,如疏散时间预测、基于性能化的设计分析等。Zukoski (Fireand Materials,1978,2(2): 54-62)在室内火灾烟气运动的开创性研究给出了基于质量和能量平衡的理论方法,为后续研究奠定了基础。然而实验发现,由于忽略热损失偏差,模型对近壁面火源的火灾烟气沉降时间的预测缺乏准确度。本文通过空间重构的方法消除房间长宽比因素造成的热损失偏差,引入两个参数进行表征,以完善该模型。完善后的模型预测烟气沉降时间与实验吻合度非常好,验证了该方法的有效性。在计算分析基础上,将两个参数对模型的影响作了评估,发现其一对模型预测结果的影响远大于另一参数。火源大小确定后,烟气充满房间的时间范围可确定,火源功率越大,时间范围越小。