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For spaceborne phased arrays, real-time antenna calibration plays a critically important role. It is the premise of high performance digital beamforming. Conventional antenna calibration approaches usually need to interrupt normal communication traffic flows to perform calibration and thus data satellite communications are interrupted. In this paper, an online calibration method without interrupting...
Nowadays, there are many serious cyber security threats such as viruses, worms and trojans but without a doubt botnets are one of the largest threats. Although there are numerous ways to discover botnets and mitigate their effects, most methods have problems effecting detection, due to their evasive characteristics. Also, the majority of previous research uses only one data source (e.g. network traffic),...
There is a large demand in the area of video-surveillance, especially in people detection, which has caused a large increase in the number of researches and resources in this field. As training images and annotations are not always available, it is important to consider the cost involved in creating the detector models. For example, for elderly people detection, the detector must have into account...
Physical unclonable functions (PUFs) are devices which are easily probed but difficult to predict. Optical PUFs have been discussed within the literature, with traditional optical PUFs typically using spatial light modulators, coherent illumination, and scattering volumes; however, these systems can be large, expensive, and difficult to maintain alignment in practical conditions. We propose and demonstrate...
This paper presents a zero-current detector (ZCD) applied in high-frequency synchronous buck DC-DC converters to enable DCM/PFM operation mode. The proposed ZCD is designed based on power efficient synchronous comparators operating in different frequency, of which coarse comparator predetermines operating period of fine comparator while inductor current zero-crossing is accurately detected by fine...
Action recognition is still a challenging problem. In order to catch effective compact representation of the action sequences, the discriminative dictionaries could be learned by sparse coding. But sparse coding is needed in both the training and testing phases of the classifier framework. And it is also time consuming for the adoption of 1-norm sparsity constraint on the representation coefficients...
Pedestrian detection is an important topic in object detection. Compared with other object detectors, YOLOv2 achieves high accuracy and fast speed for general object detection, however it degrades accuracy when detecting crowed pedestrians. In this paper, combining with the skip structure of FCN, we tailor the YOLOv2 network to improve the accuracy in detecting small pedestrians which appear in groups...
Nowadays, visual features play a key role, as they can provide a concise representation of visual data that is efficient for multiple tasks, notably content retrieval and object recognition. In parallel, visual sensors have been improving, targeting richer acquisitions of the light in a visual scene. In this context, the so-called light field cameras, which have recently emerged, are able to go beyond...
We present an Automatic License Plate Recognition system designed around Convolutional Neural Networks (CNNs) and trained over synthetic plate images. We first design CNNs suitable for plate and character detection, sharing a common architecture and training procedure. Then, we generate synthetic images that account for the varying illumination and pose conditions encountered with real plate images...
A novel holographic-based sensing system for the determination of aerosol particle number concentrations is presented. A model was designed to support both the development of a new counting algorithm and the conception of a measurement setup.
We present a fast, large active area, and large field of view photodetector; a main challenge of free-space optical communications. We use fluorescent materials to increase the active area of a photodiode by orders of magnitude, maintaining its short response time and large field of view.
In massive multiple-input multiple-output (MIMO) mobile system, the computational complexity of signal detection increases exponentially along with the growing number of antennas. For example, the sub-optimal linear detection schemes, such as zero forcing (ZF) detector and minimum mean square error (MMSE) detector, always have to balance the performance and complexity resulted from the large-scale...
This paper is devoted to traffic sign recognition problem in real time. The recognition process consists of three steps. The first step is a search of image parts which probably contain a traffic sign. The second step is about parts extraction and simple classification by shape. The last step consists of classification of extracted parts with previously learned multilayered neural net. The results...
Fruit flies are of huge biological and economic importance for the farming of different countries in the World, especially for Brazil. Brazil is the third largest fruit producer in the world with 44 million tons in 2016. The direct and indirect losses caused by fruit flies can exceed USD 2 billion, putting these pests as one of the biggest problems of the world agriculture. In Brazil, it is estimated...
Terahertz (THz) waves, which represent the frequency region between radio and light waves from 0.1 THz to 10 THz, have attracted considerable attention in the interdisciplinary field of electronics and photonics. Their unique potential applications, such as in ultra-broadband wireless communication, spectroscopic sensing, and non-destructive imaging, are now being developed [1]. However, most existing...
There has been significant advancement in photonic infrared (IR) detector technology in the past decade. In this tutorial, I will cover the basics of photonic IR detectors including the detection mechanisms and figures of merit. I will end with a survey of a few current technologies. Infrared imaging (3–25μm) has been an important technological tool for the past 60 years since the first report of...
Silicon PMTs revolutionized the High Energy Physics instrumentation, first for the Calorimeters. Exploiting the Silicon PM technology and beyond, their pixel structure and avalanche regime, leads to novel tracking techniques, either applied to large area tracking systems or digital 3D avalanche pixel devices.
We study an entangled QKD system using photons at 780nm, 1550nm and 4μm from a SPDC nonlinear crystal, over a 30km maritime channel. An analysis of the channel at each wavelength is performed and the QKD system is simulated for each wavelength.
Using a properly designed power profile allows a decode and forward (DF) method to achieve the cooperative diversity. In this paper, we consider a detect and forward (DF) strategy in which we propose an ML detector at the destination of a MIMO relay network to collect diversity when the cooperating relay adopts a zero forcing (ZF) equalizer with a proposed power profile. We provide some analysis and...
There is a demand to further improve upon performance parameter of particle detectors for high luminosity applications. Higher breakdown voltage, larger signal, lower leakage current and low noise is the primary requirement for future detectors. We want systematic study and investigate one of the important parameters namely the breakdown voltage and want to achieve optimum result for future detectors...
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