Current Issue : October - December Volume : 2019 Issue Number : 4 Articles : 5 Articles
This paper presents an iterative algorithm for the synthesis of the three-dimensional\n(3D) radiation pattern generated by an antenna array of arbitrary geometry. The algorithm is\nconceived to operate in fifth-generation (5G) millimeter-wave scenarios, thus enabling the support of\nmulti-user mobile streaming and massive peer-to-peer communications, which require the possibility\nto synthesize 3D patterns with wide null regions and multiple main beams. Moreover, the proposed\nsolution adopts a phase-only control approach to reduce the complexity of the feeding network\nand is characterized by a low computational cost, thanks to the closed-form expressions derived\nto estimate the phase of each element at the generic iteration. These expressions are obtained from\nthe minimization of a weighted cost function that includes all the necessary constraints. To finally\ncheck its versatility in a 5G environment, the developed method is validated by numerical examples\ninvolving planar and conformal arrays, considering desired patterns with different numbers of main\nbeams and nulls....
Due to complicated noise interference, seismic signals of high arch dam are of non stationarity and a low signal-to-noise ratio\n(SNR) during acquisition process. The traditional denoising method may have filtered effective seismic signals of high arch dams.\nA self-adaptive denoising method based on ensemble empirical mode decomposition (EEMD) combining wavelet threshold with\nsingular spectrum analysis (SSA) is proposed in this paper. Based on the EEMD result for seismic signals of high arch dams, a\ncontinuous mean square error criterion is used to distinguish high-frequency and low-frequency components of the intrinsic\nmode functions (IMFs). Denoised high-frequency IMF using wavelet threshold is reconstructed with low-frequency components,\nand SSA is implemented for the reconstructed signal. Simulation signal denoising analysis indicates that the proposed method can\nsignificantly reduce mean square error under low SNR condition, and the overall denoising effect is superior to EEMD and\nEEMD-Wavelet threshold denoising algorithms. Denoising analysis of measured seismic signals of high arch dams shows that the\nperformance of denoised seismic signals using EEMD-Wavelet-SSA is obviously improved, and natural frequencies of the high\narch dams can be effectively identified....
The outstanding advantage of digital signal processing (DSP) techniques and\nField Programmable Gate Array (FPGA) technology is capable of improving\nthe quality of the experimental measurements for nuclear radiation. In this\narticle, a compact DMCA 8 K was designed and manufactured using DSP\ntechnique based on FPGA technology. In particular, the output of the preamplifier\nis completely processed by digital techniques which are obtained from\nthe analog-to-digital converter (ADC) to calculate the baseline, DC offset,\nenergy peaks, pile up, threshold discrimination and then the form of energy\nspectrum. The Spartan-6 board is used as a hardware for the development of\nthe digital multichannel analyzer (DMCA), which is equipped with the\n14-bit AD6645 with 62.5 Msps sample rate. The application software for instrument\ncontrol, data acquisition and data processing was written under\nC++ builder via the RS-232 interface. The designed DMCA system has been\ntested with a HPGe detector using gamma sources of ^60Co and ^137Cs and a\nreference pulser....
Localization for visually impaired people in dynamically changing environments\nwith unexpected hazards and obstacles is a current need. Many techniques\nhave been discussed in the literature with respect to location-based\nservices and techniques used for the positioning of devices. Time difference of\narrival (TDOA), time of arrival (TOA) and received signal strength (RSS)\nhave been widely used for the positioning but narrow band signals such as\nBluetooth cannot efficiently utilize TDOA or TOA. Received signal strength\nindicator (RSSI) to measure RSS, has been found to be more reliable. RSSI\nmeasurement estimations depend heavily on the environmental interference.\nRSSI measurement estimations of Bluetooth systems can be improved either\nby improving the existing methodologies used to implement them or by using\nfusion techniques that employ Kalman filters to combine more than one RSSI\nmethod to improve the results significantly. This paper focuses on improving\nthe existing methodology of measuring RSSI by proposing a new method using\ntrilateration for localization of Bluetooth devices for visually impaired\npeople. To validate the new method, class 2 Bluetooth devices (Blue Giga\nWT-12) were used with an evaluation board. The software required was developed\nin National Instruments LabView. The PCB was designed and manufactured\nas well. Experiments were then conducted, and surface plots of\nBluetooth modules were obtained to show the signal interference and other\nenvironmental effects. Lastly, the results were discussed, and relevant conclusions\nwere drawn....
In this paper, we propose a method for calculating the dynamic background region in a video\nand removing false positives in order to overcome the problems of false positives that occur due to\nthe dynamic background and frame drop at slow speeds. Therefore, we need an efficient algorithm\nwith a robust performance value including processing speed. The foreground is separated from the\nbackground by comparing the similarities between false positives and the foreground. In order to\nimprove the processing speed, the median filter was optimized for the binary image. The proposed\nmethod was based on a CDnet 2012/2014 dataset and we achieved precision of 76.68%, FPR of 0.90%,\nFNR of 18.02%, and an F-measure of 75.35%. The average ranking across categories is 14.36, which is\nsuperior to the background subtraction method. The proposed method was operated at 45 fps (CPU),\n150 fps (GPU) at 320*240 resolution. Therefore, we expect that the proposed method can be applied\nto current commercialized CCTV without any hardware upgrades....
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