A novel adjustable dual-band bandpass filter using a quantic-mode resonator consisting of stepped impedance resonators (SIRs) and coplanar waveguide resonators (CPWRs) is proposed in this paper. The SIRs provide the lower passband with two transmission poles (TPs), while the upper passband is introduced by CPWRs and two TPs are obtained. Furthermore, an equivalent rectangular loop resonator (RLR) derived from the CPWRs is also introduced, providing another TP for the upper passband. One of the marked features of the filter is that the two passbands can be adjusted independently because of the independent resonant paths of different resonators. Besides, this filter has four transmission zeros (TZs), promising good stopband rejection and high band-to-band isolation. The measured results are consistent with the simulated results.
Elevation datasets (e.g. point clouds) are an essential but often unavailable ingredient for the construction of 3D city models. We investigate in this paper to what extent can 3D city models be generated solely from 2D data without elevation measurements. We show that it is possible to predict the height of buildings from 2D data (their footprints and attributes available in volunteered geoinformation and cadastre), and then extrude their footprints to obtain 3D models suitable for a multitude of applications. The predictions have been carried out with machine learning techniques (random forests) using 10 different attributes and their combinations, which mirror different scenarios of completeness of real-world data. Some of the scenarios resulted in surprisingly good performance (given the circumstances): we have achieved a mean absolute error of 0.8m in the inferred heights, which satisfies the accuracy recommendations of CityGML for LOD1 models and the needs of several GIS analyses. We show that our method can be used in practice to generate 3D city models where there are no elevation data, and to supplement existing datasets with 3D models of newly constructed buildings to facilitate rapid update and maintenance of data. 相似文献