Assessment of the impacts of surface topography, off-nadir pointing and vegetation structure on vegetation lidar waveforms using an extended geometric optical and radiative transfer model

In order to prioritize the measurement requirements and accuracies of the two new lidar missions, a physical model is required for a fundamental understanding of the impact of surface topography, footprint size and off-nadir pointing on vegetation lidar waveforms and vegetation height retrieval. In this study, we extended a well developed Geometric Optical and Radiative Transfer (GORT) vegetation lidar model to take into account for the impacts of surface topography and off-nadir pointing on vegetation lidar waveforms and vegetation height retrieval and applied this extended model to assess the aforementioned impacts on vegetation lidar waveforms and height retrieval.Model simulation shows that surface topography and off-nadir pointing angle stretch waveforms and the stretching effect magnifies with footprint size, slope and off-nadir pointing angle. For an off-nadir pointing laser penetrating vegetation over a slope terrain, the waveform is either stretched or compressed based on the relative angle. The stretching effect also results in a disappearing ground peak return when slope or off-nadir pointing angle is larger than the “critical slope angle”, which is closely related to various vegetation structures and footprint size. Model simulation indicates that waveform shapes are affected by surface topography, off-nadir pointing angle and vegetation structure and it is difficult to remove topography effects from waveform extent based only on the shapes of waveform without knowing any surface topography information.Height error without correction of surface topography and off-nadir pointing angle is the smallest when the laser beams at the toward-slope direction and the largest from the opposite direction. Further simulation reveals within 20° of slope and off-nadir pointing angle, given the canopy height as roughly 25 m and the footprint size as 25 m, the error for vegetation height (RH100) ranges from − 2 m to greater than 12 m, and the error for the height at the medium energy return (RH50) from − 1 m to 4 m. The RH100 error caused by unknown surface topography and without correction of off-nadir pointing effect can be explained by an analytical formula as a function of vegetation height, surface topography, off-nadir pointing angle and footprint size as a first order approximation. RH50 is not much affected by topography, off-nadir pointing and footprint size. This forward model simulation can provide scientific guidance on prioritizing future lidar mission measurement requirements and accuracies.     

Reprocessing the MODIS Leaf Area Index products for land surface and climate modelling

Land surface and climate modelling requires continuous and consistent Leaf Area Index (LAI). High spatiotemporal resolution and long-time record data are more in demand nowadays and will continue to be in the future. MODIS LAI products meet these requirements to some degree. However, due to the presence of cloud and seasonal snow cover, the instrument problems and the uncertainties of retrieval algorithm, the current MODIS LAI products are spatially and temporally discontinuous and inconsistent, which limits their application in land surface and climate modelling. To improve the MODIS LAI products on a global scale, we considered the characteristics of the MODIS LAI data and made the best use of quality control (QC) information, and developed an integrated two-step method to derive the improved MODIS LAI products effectively and efficiently on a global scale. First, we used the modified temporal spatial filter (mTSF) method taking advantage of background values and QC information at each pixel to do a simple data assimilation for relatively low quality data. Then we applied the post processing-TIMESAT (A software package to analyze time-series of satellite sensor data) Savitzky-Golay (SG) filter to get the final result. We implemented the method to 10 years of the MODIS Collection 5 LAI data. In comparison with the LAI reference maps and the MODIS LAI data, our results showed that the improved MODIS LAI data are closer to the LAI reference maps in magnitude and also more continuous and consistent in both time-series and spatial domains. In addition, simple statistics were used to evaluate the differences between the MODIS LAI and the improved MODIS LAI.     

Simulating multiple class urban land-use/cover changes by RBFN-based CA model

Land use systems are complex adaptive systems, and they are characterized by emergence, nonlinearity, feedbacks, self organization, path dependence, adaptation, and multiple-scale characteristics. Land use/cover change has been recognized as one of the major drivers of global environmental change. This paper presents a coupled Cellular Automata (CA) and Radial Basis Function Neural (RBFN) Network model, which combines Geographic Information Systems (GIS) to contribute to the understanding of the complex land use/cover change process. In this model, GIS analysis is used to generate spatial drivers of land use/cover changes, and RBFN is trained to extract model parameters. Through the RBFN-CA model, the conversion probabilities of each cell from its initial land use state to the target type can be generated automatically. Future land use/cover scenarios are projected by using generated parameters in the model training process. This RBFN-CA model is tested based on the comparison of model output and the real data. A BPN-CA model is also built and compared with the RBFN-CA model by using a variety of calibration metrics, including confusion matrix, figure of merit, and landscape metrics. Both the location and landscape metrics based assessment for model simulation indicate that the RBFN-CA model performs better than the BPN-CA model for simulating land use changes in the study area. Therefore the RBFN-CA model is capable of simulating multiple classes of land use/cover changes and can be used as a useful communication environment for stakeholders involved in land use decision-making.     

Development and application of a simulation model for changes in land-use patterns under drought scenarios

In arid and semiarid areas of northern China, one of the most vulnerable regional environments, water resources are a key constraint on socioeconomic development. We constructed a simulation model for land-use patterns under a drought transition (i.e., the increased frequency and duration of drought since the late 1970s in the Yongding River Basin study area) to account for the complexity of both the driving factors behind land-use change and the micro-level changes in land-use patterns. This model was a combination of the “top-down” system dynamics model, the “bottom-up” cellular automaton model, and the artificial neural network model. In this model, we considered the socioeconomic development and water resource restrictions, as well as the balance between the land-use requirements and the land supply. We then verified the model through a case study. The results demonstrated the value of constructing a simulation model driven by water resource constraints under the influence of drought. The spatial distribution of land uses in future scenarios will help support decision-making for sustainable regional development.     

Deformation effect of lateral roof roadway in close coal seams after repeated mining

This paper analyzed the deformation mechanism in lateral roof roadway of the Ding Wu-3 roadway which was disturbed by repeated mining of close coal seams Wu-8 and Wu-10 in Pingdingshan No. 1 Mine. To determine the strata disturbance scope, the strata displacement angle was used to calculate the protection pillar width. A numerical model was built considering the field geological conditions. In simulation, the mining stress borderline was defined as the contour where the induced stress is 1.5 times of the original stress. Simulation results show the mining stress borderline of the lateral roadway extended 91.7 m outward after repeated mining. Then the original stress increased, deforming the roadway of interest. This deformation agreed with the in situ observations. Moreover, the strata displacement angle changed due to repeated mining. Therefore, reselection of the displacement angle was required to design the protective pillar width. Since a constant strata displacement angle was used in traditional design, the proposed method was beneficial in field cases.     

Bioelectrodynamics in living organisms

This article introduces an interdisciplinary subject of bioelectrodynamics in living organisms and its related research challenges and opportunities. Bioelectrodynamics in living organisms is aimed to reveal critical roles of electromagnetism and mechanics in biology, to correlate biophysical functions of living organisms with biochemical processes at the cellular level, and to introduce theoretical basis and methodology, such as modeling and simulations, for stimulating technical innovations and promoting technology development in biomedicine as well as for the study of human healthcare issues related to environments among others in our modern society. The article reviews some important issues in bioelectrodynamic modeling. This includes the modeling of living cells, blood, bones and soft tissues that may have unique properties, such as active control, regulation and remodeling capabilities that are completely different from those of conventionally man-made materials. Possible biological effects and potential biomedical usages of endogenous and exogenous electromagnetic fields and mechanical stresses in living organisms are also reviewed, which indicate promising future of biomedical imaging and therapeutic methods based on bioelectrodynamic techniques. The fact that living organisms may have well-organized structures, actively controlled actions and responses, extremely sensitivity in electromagnetic fields and mechanical actions, and amazing signal amplification functions may not only cause complexity and variety of the biological world, but also create opportunities for technical innovations in biomedicine to improve future quality of human life.     

Q型聚类分析在确定成矿脉岩中的应用——以桦甸大庙子-菜抢子金矿区为例

吉林桦甸大庙子-菜抢子金矿区脉岩十分发育,且与成矿关系密切。通过近两年对该矿区实际地质调查研究,并重新采集各矿床脉岩、矿石样品30件,以Au、Ag、Cu等8种成矿元素作为变量,用Q型聚类分析的相关系数法进行了统计计算,计算得出金-黄铁矿型矿体与辉绿岩、煌斑岩、花岗斑岩有关;金-多金属型矿体主要与二长花岗斑岩、闪长玢岩有关,并与实际地质调查认识一致。由此明确了本矿区随着岩浆由中性向酸性演化,成矿由贵金属向多金属矿化转变。并在空间上形成叠加．     

熊耳山地区七里坪F60 -Ⅰ金银矿体地质特征及趋势预测成效

在全国老矿山深部找矿项目实施过程中,根据已获得矿山深部勘查成果,以及系统收集的研究区地质勘查和科学研究成果,发现七里坪F60-I金银矿脉的深部又出现了金品位再次升高的趋势。通过研究已知矿体的空间赋存状态、分布规律与成矿特征,分析中深部构造成矿、控矿特征及成矿元素变化规律,基于MapGIS DTM空间数据分析,采用权值等值线进行了矿体空间延伸趋势预测,系统分析了矿体的三维空间状态。参考已有矿体工程验证效果,调整了矿体空间预测方案与验证工程,并获得了良好的深部预测效果,实现了老矿山深部整装勘查找矿的突破,对研究区中深部找矿工程部署乃至整个小秦岭地区深部找矿具有很好的指导意义和示范效应,有效促进了小秦岭地区深部地质找矿工作的工程部署和勘探验证工程的实施。     

交鲁山—东天山火山岩带HS-8金异常查证

交鲁山—东天山火山岩带位于大兴安岭德尔布干成矿带东北端,1∶5万水系沉积物测量圈出了一处显示Au成矿潜力的HS-8化探组合异常,运用大比例尺土壤地球化学测量、激电中梯测量方法,对可能导致HS-8化探组合异常的深部隐伏控矿构造及矿化蚀变进行了查证。查证结果:共圈定地球化学组合异常6处,推断断裂构造4条;对1∶2万土壤地球化学测量、激电中梯测量异常进行了槽探工程验证,并根据化学样分析结果圈出了6条金矿(化)体。研究表明,激电中梯测量视极化率(ηs)异常主要与黄铁(褐铁)矿化有关,成矿元素金在英安岩和流纹岩中具有明显的富集趋势,这两种岩石可能为金矿化提供了物质来源。     

Benthic Community and Sediment Quality Assessment of Port Hope Harbour,Lake Ontario

Sediments in Port Hope Harbour, Lake Ontario, have been heavily contaminated by radionuclides and heavy metals from a radium recovery plant, a uranium refinery, and other industrial activities. Spatial patterns in surficial sediment contamination, benthic community structure, and bioaccumulation of contaminants were assessed to determine possible relationships and potential environmental hazards in the event of dredging. Benthic community differences in species composition and density between inner and outer harbour areas corresponded with both habitat and sediment quality differences. Sediment loss-on-ignition, nitrogen, iron, copper, lead, chromium, zinc, and nickel concentrations in the inner harbour exceeded provincial guidelines for open water disposal of dredged spoils. Only iron exceeded those guidelines in the outer harbour. Tissue levels of radionuclides and heavy metals in benthic invertebrates were greatest at the most heavily contaminated stations in the inner harbour. Reduced benthic densities and maximum sediment contamination occurred near a refinery cooling water discharge.