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Chi-yang Chang – One of the best experts on this subject based on the ideXlab platform.
A switchable tunable dual-Band Filter using varator diodes for tuning and switching2017 IEEE CPMT Symposium Japan (ICSJ), 2017Co-Authors: Po-jung Chou, Chi-yang ChangAbstract:
A switchable tunable dual-Band Filter using varator diodes for Band switching and frequency tuning is proposed. The tuning range of first Band is from 2.3 to 2.8 GHz and second one is from 1.8 to 2.1 GHz. The proposed dual-Band Filter is composed of two second-order Chebyshev short-ended hairpin comb Filters which embedded a pair of the varators as a switching and tuning elements. The simulated and measured results are matched well.
Tri-Band and quad-Band Filter design using E-shaped resonators, 2011Co-Authors: Yi-ting Kuo, Shi-yu Cheng, Chi-yang ChangAbstract:
The semi-analytic procedure is provided for tri-Band and quad-Band Filter design based on E-shaped resonators. With analytic synthesized procedure in dual-Band Filter design and connect two Filters using double-diplexing configuration, the tri-Band and quad-Band performances can be achieved. The simulated results for the synthesized Filters agree well with the ideal performances after some fine tuning. Two microstrip implementations are provided to demonstrate the reliability of tri-Band and quad-Band Filter design.
analytical design of microstrip short circuit terminated stepped impedance resonator dual Band FiltersIEEE Transactions on Microwave Theory and Techniques, 2011Co-Authors: Weishin Chang, Chi-yang ChangAbstract:
This paper proposes an analytical method to design a dual-Band Alter using the short-circuit terminated half-wavelength stepped-impedance resonator (SIR). The SIR has an advantage to easily control the first and second resonances by adjusting its structural parameters. In the proposed method, the structural parameters of the SIR are obtained analytically according to the two passBand center frequencies and Bandwidths of the Filter. As a result, the achievable specifications of the dual-Band Filter can be rapidly determined. The coupling between adjacent SIRs is realized by a short-circuited stub, which is characterized as a K-inverter network. The dual-frequency transformer incorporated with the tapped-line input/output structure is used for the external coupling. Applying the analytical equations in the design process, a dual-Band Filter can be easily and quickly realized. More importantly, compared to the published dual-Band Filters, the proposed method is easier to design, especially for a relatively high-order dual-Band Filter. Two fourth-order and one sixth-order dual-Band Filters are designed and fabricated to demonstrate the proposed method.
Chang-hong Liang – One of the best experts on this subject based on the ideXlab platform.
a compact hexagonal dual Band substrate integrated waveguide Filter based on extracted pole techniqueMicrowave and Optical Technology Letters, 2011Co-Authors: Jia Chen, Bian Wu, Liwei Jiang, Chang-hong LiangAbstract:
In this article, a novel hexagon substrate integrated waveguide (SIW) dual-Band Filter is presented.First, the formula for calculating the resonant frequency of the dominant mode in triangle SIW cavity is given, then the triangle SIW cavity is used to construct a novel hexagon Filter, which reduces the size effectively. According to the extracted-pole technique using a parallel resonant circuit at the input and output resonator, a dual-Band Filter with two passBands at 9.6–9.85 and 10.15–10.4 GHz has been designed and fabricated. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:562–565, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25799
design of tri Band Filter based on stub loaded resonator and dgs resonatorIEEE Microwave and Wireless Components Letters, 2010Co-Authors: Chang-hong Liang, Hao Di, Bian WuAbstract:
A tri-Band Bandpass Filter using stub loaded resonator (SLR) and defected ground structure (DGS) resonator is proposed in this letter. The DGS resonator on the lower plane constructs the first pass-Band, and the SLR on the upper plane forms the second and third pass-Bands, in which a DGS loop is properly used to provide the coupling between the SLRs. The three pass-Bands are combined together with a common T-shaped feed line, and a reasonable tuning method is adopted to tune the three pass-Bands with smooth responses. A compact tri-Band Filter with three pass-Bands centered at 2.45, 3.5, and 5.25 GHz is designed and fabricated. The measurement results agree well with the full-wave electromagnetic designed responses.
Design of Tri-Band Filter Based on Stub, 2010Co-Authors: Xin Lai, Chang-hong LiangAbstract:
Atri-BandBandpassFilterusingstubloadedresonator (SLR) and defected ground structure (DGS) resonator is proposed in this letter. The DGS resonator on the lower plane constructs the first pass-Band, and the SLR on the upper plane forms the second and third pass-Bands, in which a DGS loop is properly used to pro- videthecouplingbetweentheSLRs.Thethreepass-Bandsarecom- bined together with a common T-shaped feed line, and a reason- able tuning method is adopted to tune the three pass-Bands with smooth responses. A compact tri-Band Filter with three pass-Bands centered at 2.45, 3.5, and 5.25 GHz is designed and fabricated. The measurement results agree well with the full-wave electromagnetic designed responses. Index Terms—Defected ground structure (DGS) resonator, stub- loaded resonator (SLR), tri-Band Filter, T-shaped feed line.
Aurelio Campilho – One of the best experts on this subject based on the ideXlab platform.
optic disc segmentation using the sliding Band FilterComputers in Biology and Medicine, 2015Co-Authors: Behdad Dashtbozorg, Ana Maria Mendonca, Aurelio CampilhoAbstract:
Background: The optic disc (OD) centre and boundary are important landmarks in retinal images and are essential for automating the calculation of health biomarkers related with some prevalent systemic disorders, such as diabetes, hypertension, cerebrovascular and cardiovascular diseases.
Methods: This paper presents an automatic approach for OD segmentation using a multiresolution sliding Band Filter (SBF). After the preprocessing phase, a low-resolution SBF is applied on a downsampled retinal image and the locations of maximal Filter response are used for focusing the analysis on a reduced region of interest (ROI). A high-resolution SBF is applied to obtain a set of pixels associated with the maximum response of the SBF, giving a coarse estimation of the OD boundary, which is regularized using a smoothing algorithm.
Results: Our results are compared with manually extracted boundaries from public databases (ONHSD, MESSIDOR and INSPIRE-AVR datasets) outperforming recent approaches for OD segmentation. For the ONHSD, 44% of the results are classified as Excellent, while the remaining images are distributed between the Good (47%) and Fair (9%) categories. An average overlapping area of 83%, 89% and 85% is achieved for the images in ONHSD, MESSIDOR and INSPIR-AVR datasets, respectively, when comparing with the manually delineated OD regions.
Discussion: The evaluation results on the images of three datasets demonstrate the better performance of the proposed method compared to recently published OD segmentation approaches and prove the independence of this method when from changes in image characteristics such as size, quality and camera field of view.
Cell Nuclei and Cytoplasm Joint Segmentation Using the Sliding Band FilterIEEE Transactions on Medical Imaging, 2010Co-Authors: Pedro Quelhas, Ana Maria Mendonca, Monica Marcuzzo, Aurelio CampilhoAbstract:
Microscopy cell image analysis is a fundamental tool for biological research. In particular, multivariate fluorescence microscopy is used to observe different aspects of cells in cultures. It is still common practice to perform analysis tasks by visual inspection of individual cells which is time consuming, exhausting and prone to induce subjective bias. This makes automatic cell image analysis essential for large scale, objective studies of cell cultures. Traditionally the task of automatic cell analysis is approached through the use of image segmentation methods for extraction of cells’ locations and shapes. Image segmentation, although fundamental, is neither an easy task in computer vision nor is it robust to image quality changes. This makes image segmentation for cell detection semi-automated requiring frequent tuning of parameters. We introduce a new approach for cell detection and shape estimation in multivariate images based on the sliding Band Filter (SBF). This Filter‘s design makes it adequate to detect overall convex shapes and as such it performs well for cell detection. Furthermore, the parameters involved are intuitive as they are directly related to the expected cell size. Using the SBF Filter we detect cells’ nucleus and cytoplasm location and shapes. Based on the assumption that each cell has the same approximate shape center in both nuclei and cytoplasm fluorescence channels, we guide cytoplasm shape estimation by the nuclear detections improving performance and reducing errors. Then we validate cell detection by gathering evidence from nuclei and cytoplasm channels. Additionally, we include overlap correction and shape regularization steps which further improve the estimated cell shapes. The approach is evaluated using two datasets with different types of data: a 20 images benchmark set of simulated cell culture images, containing 1000 simulated cells; a 16 images Drosophila melanogaster Kc167 dataset containing 1255 cells, stained for DNA and actin. Both image datasets present a difficult problem due to the high variability of cell shapes and frequent cluster overlap between cells. On the Drosophila dataset our approach achieved a precision/recall of 95%/69% and 82%/90% for nuclei and cytoplasm detection respectively and an overall accuracy of 76%.