声表面波谐振型无源无线温度传感器硬件系统

介绍了一种基于声表面波谐振器的无源无线温度传感系统,系统采用一次变频的构成方式,解决了传统传感系统存在电路结构复杂和控制灵活性差的缺点,给出了系统的具体构成、工作原理和天线的设计。与传统系统构成相比,本系统的构成更简洁,操作性和灵活性更强。实验验证了本系统构成方式的可行性和天线设计的优点。     

激光遥测甲烷气体最低可探测浓度

对一种使用单一激光源遥感检测甲烷方案的最低可探测的路径-积分浓度进行了理论分析和实验研究,该方案主要采用了频率调制及谐波探测技术。通过理论计算得出了最低可探测甲烷的路径-积分浓度大约为8.7×10-8m。实验中测得该探测系统的探测灵敏度为8.43×10-6m/mV,甲烷最低可探测路径-积分浓度为4.2×10-7m。结果表明该探测系统具有较高的探测灵敏度,完全满足对矿井瓦斯的实时监测要求。     

Simulated Bacterially-Inspired Problem Solving – The Behavioural Domain

Bacterial populations meet the challenges of dynamic spatially heterogeneous environments with fluctuating biotic and abiotic factors in a number of ways. The motivation for the work presented here has been to transfer ideas from bacterial adaptability and evolvability to computational problem solving. Following a brief comment on some examples of the ways bacteria solve problems, a bacterially-inspired computational architecture for simulating aspects of problem solving is described. We then examine three case studies. The first, a study of the mutational impact of a remediation to toxic (fitness-reducing) material, highlights how a sufficiently pre-engineered adaptive system can solve a difficult problem quite easily. The second study looks at why it is difficult to evolve complex problem solving behaviours and how artificial selection mechanisms coupled with pre-engineering the system can help. Specifically, this refers to quorum sensing and tactic behaviours. A further study looked at ways in which a quorum sensing analogue could help computational agents find multiple peaks in a landscape. The paper concludes with a discussion of an investigation of bacteria that had both quorum sensing and tactic capabilities.     

Integration of radar and Landsat-derived foliage projected cover for woody regrowth mapping, Queensland, Australia

In Queensland, Australia, forest areas are discriminated from non-forest by applying a threshold (∼ 12%) to Landsat-derived Foliage Projected Cover (FPC) layers (equating to ∼ 20% canopy cover), which are produced routinely for the State. However, separation of woody regrowth following agricultural clearing cannot be undertaken with confidence, and is therefore not mapped routinely by State Agencies. Using fully polarimetric C-, L- and P-band NASA AIRSAR and Landsat FPC data for forests and agricultural land near Injune, central Queensland, we corroborate that woody regrowth dominated by Brigalow (Acacia harpophylla) cannot be discriminated using either FPC or indeed C-band data alone, because the rapid attainment of a canopy cover leads to similarities in both reflectance and backscatter with remnant forest. We also show that regrowth cannot be discriminated from non-forest areas using either L-band or P-band data alone. However, mapping can be achieved by thresholding and intersecting these layers, as regrowth is unique in supporting both a high FPC (> ∼ 12%) and C-band SAR backscatter (> ~ − 18 dB at HV polarisation) and low L-band and P-band SAR backscatter (e.g. < =∼ 14 dB at L-band HH polarisation). To provide a theoretical explanation, a wave scattering model based on that of Durden et al. [Durden, S.L., Van Zyl, J.J. & Zebker, H.A. (1989). Modelling and observation of radar polarization signature of forested areas. IEEE Trans. Geoscience and Remote Sensing, 27, 290-301.] was used to demonstrate that volume scattering from leaves and small branches in the upper canopy leads to increases in C-band backscattering (particularly HV polarisations) from regrowth, which increases proportionally with FPC. By contrast, low L-band and P-band backscatter occurs because of the lack of double bounce interactions at co-polarisations (particularly HH) and volume scattering at HV polarisation from the stems and branches, respectively, when their dimensions are smaller than the wavelength. Regrowth maps generated by applying simple thresholds to both FPC and AIRSAR L-band data showed a very close correspondence with those mapped using same-date 2.5 m Hymap data and an average 73.7% overlap with those mapped through time-series comparison of Landsat-derived land cover classifications. Regrowth mapped using Landsat-derived FPC from 1995 and JER-1 SAR data from 1994-1995 also corresponded with areas identified within the time-series classification and true colour stereo photographs for the same period. The integration of Landsat FPC and L-band SAR data is therefore expected to facilitate regrowth mapping across Queensland and other regions of Australia, particularly as Japan's Advanced Land Observing System (ALOS) Phase Arrayed L-band SAR (PALSAR), to be launched in 2006, will observe at both L-band HH and HV polarisations.     

Comparing the utility of microwave and thermal remote-sensing constraints in two-source energy balance modeling over an agricultural landscape

A two-source (soil + vegetation) energy balance model using microwave-derived near-surface soil moisture as a key boundary condition (TSM_SM) and another scheme using thermal-infrared (radiometric) surface temperature (TSM_TH) were applied to remote sensing data collected over a corn and soybean production region in central Iowa during the Soil Moisture Atmosphere Coupling Experiment (SMACEX)/Soil Moisture Experiment of 2002 (SMEX02). The TSM_SM was run using fields of near-surface soil moisture from microwave imagery collected by aircraft on six days during the experiment, yielding a root mean square difference (RMSD) between model estimates and tower measurements of net radiation (Rn) and soil heat flux (G) of approximately 20 W m^− 2, and 45 W m^− 2 for sensible (H) and latent heating (LE). Similar results for H and LE were obtained at landscape/regional scales when comparing model output with transect-average aircraft flux measurements. Flux predictions from the TSM_SM and TSM_TH models were compared for two days when both airborne microwave-derived soil moisture and radiometric surface temperature (T_R) data from Landsat were available. These two days represented contrasting conditions of moderate crop cover/dry soil surface and dense crop cover/moist soil surface. Surface temperature diagnosed by the TSM_SM was also compared directly to the remotely sensed T_R fields as an additional means of model validation. The TSM_SM performed well under moderate crop cover/dry soil surface conditions, but yielded larger discrepancies with observed heat fluxes and T_R under the high crop cover/moist soil surface conditions. Flux predictions from the thermal-based two-source model typically showed biases of opposite sign, suggesting that an average of the flux output from both modeling schemes may improve overall accuracy in flux predictions, in effect incorporating multiple remote-sensing constraints on canopy and soil fluxes.     

A downscaling method for distributing surface soil moisture within a microwave pixel: Application to the Monsoon '90 data

A downscaling method for the near-surface soil moisture retrieved from passive microwave sensors is applied to the PBMR data collected during the Monsoon '90 experiment. The downscaling method requires (1) the coarse resolution microwave observations, (2) the fine-scale distribution of soil temperature and (3) the fine-scale distribution of surface conditions composed of atmospheric forcing and the parameters involved in the modeling of land surface-atmosphere interactions. During the Monsoon '90 experiment, eight ground-based meteorological and flux stations were operating over the 150 km² study area simultaneously with the acquisition of the aircraft-based L-band PBMR data. The heterogeneous scene is hence composed of eight subpixels and the microwave pixel is generated by aggregating the microwave emission of all sites. The results indicate a good agreement between the downscaled and ground-based soil moisture as long as the intensity of solar radiation is sufficiently high to use the soil temperature as a tracer of the spatial variability of near-surface soil moisture.     

Spectral Network (SpecNet)—What is it and why do we need it?

Effective integration of optical remote sensing with flux measurements across multiple scales is essential for understanding global patterns of surface-atmosphere fluxes of carbon and water vapor. SpecNet (Spectral Network) is an international network of cooperating investigators and sites linking optical measurements with flux sampling for the purpose of improving our understanding of the controls on these fluxes. An additional goal is to characterize disturbance impacts on surface-atmosphere fluxes. To reach these goals, key SpecNet objectives include the exploration of scaling issues, development of novel sampling tools, standardization and intercomparison of sampling methods, development of models and statistical methods that relate optical sampling to fluxes, exploration of component fluxes, validation of satellite products, and development of an informatics approach that integrates disparate data sources across scales. Examples of these themes are summarized in this review.     

北衙碱性斑岩型金矿床矿床遥感地质综合信息

北衙碱性斑岩型金矿床为“三江”地区金沙江－哀牢山喜山期富碱斑岩带中的重要金多金属矿床，复式穹隆构造碱性斑岩与金矿床呈现构造－－岩浆－－矿化三位一体，金矿化集中于成矿晚期热液活动阶段，矿床遥感地质方法获取了该区常规地质方法得不到的成岩成矿影像－地质信息，与构造地球化学方法共同获取了丰富的矿床定位预测网络结构“陷信息”并拟建了影像线－环结构－构造地球化学集成成矿预测方法。     

遥感数据与地理信息

遥感数据是遥感技术获取的基础数据．从遥感数据中提取地理信息是实现实时空间数据更新的主要手段，但遥感数据与地理信息之间存在着一定的差异．论文分析了遥感数据的相对性，说明遥感反演模型的局限性；分析了遥感数据的确定性与不确定性，说明遥感统计模式识别的局限性．明确遥感数据与地理信息之间的关系，并结合计算机视觉技术和遥感图像处理技术，提出基于遥感数据的地理定性、定量信息提取的概念模型．     

水源保护区划界的遥感与GIS技术研究

科学合理地划定水源地的保护范围是一项技术含量较高的工作。以厦门市饮用水源中的北溪引水渠(管道)和坂头水库为例,根据饮用水源保护区划分原则,研究基于数字化的地形图建立数字高程模型并自动生成汇水区盆地和流域范围的GIS技术、获取相关自然环境专题信息的遥感技术、以及综合利用社会和自然等多种数据源进行保护区范围界定的方法。重点探讨数字高程模型的建立以及汇水区盆地和流域边界自动生成的GIS方法。