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Total 1478 results found since Jan 2013.

Sensors, Vol. 23, Pages 4897: TCU-Net: Transformer Embedded in Convolutional U-Shaped Network for Retinal Vessel Segmentation
g Zhang Optical coherence tomography angiography (OCTA) provides a detailed visualization of the vascular system to aid in the detection and diagnosis of ophthalmic disease. However, accurately extracting microvascular details from OCTA images remains a challenging task due to the limitations of pure convolutional networks. We propose a novel end-to-end transformer-based network architecture called TCU-Net for OCTA retinal vessel segmentation tasks. To address the loss of vascular features of convolutional operations, an efficient cross-fusion transformer module is introduced to replace the original skip connection of ...
Source: Sensors - May 19, 2023 Category: Biotechnology Authors: Zidi Shi Yu Li Hua Zou Xuedong Zhang Tags: Article Source Type: research

Sensors, Vol. 23, Pages 6363: Low-Complexity Joint Angle of Arrival and Time of Arrival Estimation of Multipath Signal in UWB System
i Zhang In an ultra-wideband (UWB) system, the two-dimensional (2D) multiple signal classification (MUSIC) algorithms based on high-precision 2D spectral peak search can jointly estimate the time of arrival (TOA) and angle of arrival (AOA). However, the computational complexity of 2D-MUSIC is very high, and the corresponding data model is only based on the dual antennas. To solve these problems, a low-complexity algorithm for joint AOA and TOA estimation of the multipath ultra-wideband signal is proposed. Firstly, the dual antenna sensing data model is extended to the antenna array case. Then, based on the array-sensin...
Source: Sensors - July 13, 2023 Category: Biotechnology Authors: Weiming Deng Jianfeng Li Yawei Tang Xiaofei Zhang Tags: Article Source Type: research

Sensors, Vol. 15, Pages 19199-19211: Security Analysis of Image Encryption Based on Gyrator Transform by Searching the Rotation Angle with Improved PSO Algorithm
Gyrator transform has been widely used for image encryption recently. For gyrator transform-based image encryption, the rotation angle used in the gyrator transform is one of the secret keys. In this paper, by analyzing the properties of the gyrator transform, an improved particle swarm optimization (PSO) algorithm was proposed to search the rotation angle in a single gyrator transform. Since the gyrator transform is continuous, it is time-consuming to exhaustedly search the rotation angle, even considering the data precision in a computer. Therefore, a computational intelligence-based search may be an alternative choice. ...
Source: Sensors - August 5, 2015 Category: Biotechnology Authors: Jun SangJun ZhaoZhili XiangBin CaiHong Xiang Tags: Article Source Type: research

Sensors, Vol. 15, Pages 21581-21612: Adaptive Correlation Space Adjusted Open-Loop Tracking Approach for Vehicle Positioning with Global Navigation Satellite System in Urban Areas
In this study, the Adaptive Correlation Space Adjusted Open-Loop Tracking Approach (ACSA-OLTA) is proposed to improve the code phase measurement dependent pseudo range accuracy. In ACSA-OLTA, the correlation space is adjusted according to the signal C=N0. The novel Equivalent Weighted Pseudo Range Error (EWPRE) is raised to obtain the optimal code search grid sizes for different C=N0. The code phase measuring errors of different measurement calculation methods are analyzed for the first time. The measurement calculation strategy of ACSA-OLTA is derived from the analysis to further improve the accuracy but reduce the correl...
Source: Sensors - August 28, 2015 Category: Biotechnology Authors: Hang RuanJian LiLei ZhangTeng Long Tags: Article Source Type: research

Sensors, Vol. 16, Pages 888: Weighted Global Artificial Bee Colony Algorithm Makes Gas Sensor Deployment Efficient
This paper proposes an improved artificial bee colony algorithm named Weighted Global ABC (WGABC) algorithm, which is designed to improve the convergence speed in the search stage of solution search equation. The new method not only considers the effect of global factors on the convergence speed in the search phase, but also provides the expression of global factor weights. Experiment on benchmark functions proved that the algorithm can improve the convergence speed greatly. We arrive at the gas diffusion concentration based on the theory of CFD and then simulate the gas diffusion model with the influence of buildings base...
Source: Sensors - June 15, 2016 Category: Biotechnology Authors: Ye JiangZiqing HeYanhai LiZhengyi XuJianming Wei Tags: Article Source Type: research

Sensors, Vol. 16, Pages 1567: A Geographical Heuristic Routing Protocol for VANETs
Vehicular ad hoc networks (VANETs) leverage the communication system of Intelligent Transportation Systems (ITS). Recently, Delay-Tolerant Network (DTN) routing protocols have increased their popularity among the research community for being used in non-safety VANET applications and services like traffic reporting. Vehicular DTN protocols use geographical and local information to make forwarding decisions. However, current proposals only consider the selection of the best candidate based on a local-search. In this paper, we propose a generic Geographical Heuristic Routing (GHR) protocol that can be applied to any DTN geogr...
Source: Sensors - September 22, 2016 Category: Biotechnology Authors: Luis Urquiza-Aguiar Carolina Tripp-Barba M ónica Aguilar Igartua Tags: Article Source Type: research

Sensors, Vol. 17, Pages 2009: Position Fingerprint-Based Beam Selection in Millimeter Wave Heterogeneous Networks
hen The traditional beam selection algorithms determine the optimal beam direction by feeding back the perfect channel state information (CSI) in a millimeter wave (mmWave) massive Multiple-Input Multiple-Output (MIMO) system. Popular beam selection algorithms mostly focus on the methods of feedback and exhaustive search. In order to reduce the extra computational complexity coming from the redundant feedback and exhaustive search, a position fingerprint (PFP)-based mmWave multi-cell beam selection scheme is proposed in this paper. In the proposed scheme, the best beam identity (ID) and the strongest interference beam ...
Source: Sensors - September 1, 2017 Category: Biotechnology Authors: Zufan Zhang Yanbo Chen Tags: Article Source Type: research

Sensors, Vol. 18, Pages 1016: Diagnosing a Strong-Fault Model by Conflict and Consistency
quan Feng The diagnosis method for a weak-fault model with only normal behaviors of each component has evolved over decades. However, many systems now demand a strong-fault models, the fault modes of which have specific behaviors as well. It is difficult to diagnose a strong-fault model due to its non-monotonicity. Currently, diagnosis methods usually employ conflicts to isolate possible fault and the process can be expedited when some observed output is consistent with the model’s prediction where the consistency indicates probably normal components. This paper solves the problem of efficiently diagnosing a strong-f...
Source: Sensors - March 29, 2018 Category: Biotechnology Authors: Wenfeng Zhang Qi Zhao Hongbo Zhao Gan Zhou Wenquan Feng Tags: Article Source Type: research

Sensors, Vol. 18, Pages 1482: A Double Dwell High Sensitivity GPS Acquisition Scheme Using Binarized Convolution Neural Network
iu Longxing Shi Conventional GPS acquisition methods, such as Max selection and threshold crossing (MAX/TC), estimate GPS code/Doppler by its correlation peak. Different from MAX/TC, a multi-layer binarized convolution neural network (BCNN) is proposed to recognize the GPS acquisition correlation envelope in this article. The proposed method is a double dwell acquisition in which a short integration is adopted in the first dwell and a long integration is applied in the second one. To reduce the search space for parameters, BCNN detects the possible envelope which contains the auto-correlation peak in the first dwell ...
Source: Sensors - May 9, 2018 Category: Biotechnology Authors: Zhen Wang Yuan Zhuang Jun Yang Hengfeng Zhang Wei Dong Min Wang Luchi Hua Bo Liu Longxing Shi Tags: Article Source Type: research

Sensors, Vol. 18, Pages 1725: Reduced Dimension Based Two-Dimensional DOA Estimation with Full DOFs for Generalized Co-Prime Planar Arrays
Zhang In this paper, we investigate the problem of two-dimensional (2D) direction-of-arrival (DOA) estimation for generalized co-prime planar arrays. The classic multiple signal classification (MUSIC)-based methods can provide a superior estimation performance, but suffer from a tremendous computational burden caused by the 2D spectral search. To this end, we reduce the 2D problem into a one-dimensional (1D) one and propose a reduced dimension partial spectral search estimation method, which can compress the search region into a small 1D sector. Moreover, the proposed method can utilize the full information of the enti...
Source: Sensors - May 27, 2018 Category: Biotechnology Authors: Fenggang Sun Peng Lan Guowei Zhang Tags: Article Source Type: research

Sensors, Vol. 18, Pages 2160: A Tightly Coupled RTK/INS Algorithm with Ambiguity Resolution in the Position Domain for Ground Vehicles in Harsh Urban Environments
ngquan Lu Vehicles driving in urban canyons are always confronted with a degraded Global Navigation Satellite System (GNSS) signal environment. The surrounding obstacles may cause signal reflections or blockages, which lead to large multipath noises and intermittent GNSS reception. Under these circumstances, it is not feasible to use conventional real-time kinematic (RTK) algorithms to maintain high-precision performance for positioning. In order to meet the special requirements of safety-critical applications under non-ideal observation conditions, a novel tightly coupled RTK/Inertial Navigation System (INS) algorithm...
Source: Sensors - July 4, 2018 Category: Biotechnology Authors: Wei Li Wenyi Li Xiaowei Cui Sihao Zhao Mingquan Lu Tags: Article Source Type: research

Sensors, Vol. 18, Pages 4139: A Fast ML-Based Single-Step Localization Method Using EM Algorithm Based on Time Delay and Doppler Shift for a Far-Field Scenario
This study discusses the localization problem based on time delay and Doppler shift for a far-field scenario. The conventional location methods employ two steps that first extract intermediate parameters from the received signals and then determine the source position from the measured parameters. As opposed to the traditional two-step methods, the direct position determination (DPD) methods accomplish the localization in a single step without computing intermediate parameters. However, the DPD cost function often remains non-convex, thereby it will cost a high amount of computational resources to find the estimated positi...
Source: Sensors - November 26, 2018 Category: Biotechnology Authors: Tianzhu Qin Lin Li Bin Ba Daming Wang Tags: Article Source Type: research

Sensors, Vol. 18, Pages 4174: A Semantic-Based Gas Source Localization with a Mobile Robot Combining Vision and Chemical Sensing
lez-Jimenez This paper addresses the localization of a gas emission source within a real-world human environment with a mobile robot. Our approach is based on an efficient and coherent system that fuses different sensor modalities (i.e., vision and chemical sensing) to exploit, for the first time, the semantic relationships among the detected gases and the objects visually recognized in the environment. This novel approach allows the robot to focus the search on a finite set of potential gas source candidates (dynamically updated as the robot operates), while accounting for the non-negligible uncertainties in the objec...
Source: Sensors - November 28, 2018 Category: Biotechnology Authors: Javier Monroy Jose-Raul Ruiz-Sarmiento Francisco-Angel Moreno Francisco Melendez-Fernandez Cipriano Galindo Javier Gonzalez-Jimenez Tags: Article Source Type: research

Sensors, Vol. 19, Pages 682: A Low-Cost Electromagnetic Docking Guidance System for Micro Autonomous Underwater Vehicles
This study designed a low-cost electromagnetic docking guidance (EMDG) system for micro AUVs. The EMDG system is composed of a transmitter coil located on the dock and a three-axial search coil magnetometer acting as a receiver. The search coil magnetometer was optimized for small sizes while maintaining sufficient sensitivity. The signal conditioning and processing subsystem was designed to calculate the deflection angle (β) for docking guidance. Underwater docking tests showed that the system can detect the electromagnetic signal and successfully guide AUV docking. The AUV can still perform docking in extrem...
Source: Sensors - February 7, 2019 Category: Biotechnology Authors: Peng Liu Wu Li Liu Cai Yu Tags: Article Source Type: research

Sensors, Vol. 19, Pages 960: Double Q-Learning for Radiation Source Detection
deh Anomalous radiation source detection in urban environments is challenging due to the complex nature of background radiation. When a suspicious area is determined, a radiation survey is usually carried out to search for anomalous radiation sources. To locate the source with high accuracy and in a short time, different survey approaches have been studied such as scanning the area with fixed survey paths and data-driven approaches that update the survey path on the fly with newly acquired measurements. In this work, we propose reinforcement learning as a data-driven approach to conduct radiation detection tasks with n...
Source: Sensors - February 24, 2019 Category: Biotechnology Authors: Zheng Liu Shiva Abbaszadeh Tags: Article Source Type: research