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Smart bridge: Towards robust monitoring of environmental hazards
Published in Wim Uijttewaal, Mário J. Franca, Daniel Valero, Victor Chavarrias, Clàudia Ylla Arbós, Ralph Schielen, Alessandra Crosato, River Flow 2020, 2020
E. Koursari, S.J. Wallace, Y. Xu, P. Michalis, M. Valyrakis
For the determination of water levels, ultrasonic sensors transmit sound waves, measuring the time between the echo reaching the water and returning to the sensor. Ultrasonic sensors are contactless, being deployed above the water surface, not requiring contacting the water for measurements to be taken. Pressure transducers work by weighing the amount of water they are used to measure, therefore requiring to be submerged and sitting on the river bed for the provision of accurate measurements. The use of pressure transducers can be proven to be challenging in a river environment, where debris and sediment can affect measurements or damage them. Guided wave radar sensors send electromagnetic waves and high frequency radar to the water, through the use of probes. The measurements are taken by measuring the time it takes for the radar pulse to return to the sensor once it has been sent. Guided wave radar sensors are non-contact sensors, not requiring contacting the water they are measuring, as well as being able to penetrate things present on the water surface that may be affecting the measurements (Pultar 2018, Writer 2018). However, the latter are more costly than ultrasonic sensors and pressure transducers.
Over-the-Horizon Radar
Published in Habibur Rahman, Fundamental Principles of Radar, 2019
Detection is somewhat easier than with skywave propagation since ionospheric effects are not present and clutter returns from aurora generally can be eliminated by time gating. The surface-wave radar must be located on the coast, or on an island or ships, as even a short distance of overland path can cause severe attenuation of the transmitted and received surface wave. Overland applications are thus not desirable. The surface-wave radar has a far shorter range than with skywave radar because of the propagation loss, which increases exponentially as a function of the range, and provides a range against low-altitude aircraft targets at perhaps maximum range of 200 to 400 km. Advantages of the surface-wave radar are many: freedom from ionospheric reflection enabling the Doppler velocity discrimination and tracking more accurately; capable of avoiding long-range skywave clutter; freedom in selecting the operating frequency; and no need to follow the diurnal and seasonal ionospheric variations.
Other Applications
Published in Hisham K. Hisham, Fiber Bragg Grating Sensors, 2019
Modern operational requirements for large-scale container vessels require automatic monitoring of the state of the sea through the use of wave radars, which have become an effective tool [1]. These radars help navigation by providing the following important information: wave direction, maximum wave height, wave period, and significant wave height [1].
Multi-target CFAR detector based on compressed sensing radar system
Published in International Journal of Electronics, 2023
Boning Feng, Huotao Gao, Yunkun Yang, Fangyu Ren, Taoming Lu
In this section, we verify the performance of the proposed detector from several perspectives. The database used in the simulation is sea clutter data recorded by high-frequency ground wave radar, the radar operates at 6–9 MHz with a bandwidth of 300 kHz. By fitting the sea clutter data and selecting 90% of the best fitting data for statistical analysis, the result demonstrates that the amplitude of the echoes in the range domain obeys Weibull distribution. To illustrate the detector performance, several targets are added to the clutter. Some of the parameters used in the simulation are as follows: , compression rate , the sparsity of the signal K = 7, CFAR reference window of length 16 with 4 guard cells.
A series-fed low sidelobe antenna for 24-GHz automotive radar
Published in Electromagnetics, 2023
Millimeter wave radar can directly measure the distance, radial velocity, and angle of target through an appropriate antenna system in dark light and severe weather (Waldschmidt, Hasch, and Menzel 2021). Common millimeter wave radars include continuous wave radar and pulse radar. Frequency-modulated continuous wave (FMCW) radar system is easier to measure the speed and distance of the target without requiring high output power of the transmitter (Thomas, Bredendiek, and Pohl 2019; Vasanelli, Bögelsack, and Waldschmidt 2018; Welp et al. 2020). Automotive radars are operated in 24 GHz band mostly for short-range applications, such as blind spot detection, lane change assistance, automatic cruise control, and parking assistance (Ho and Chung 2005; Lee and Kim 2010; Meinecke et al. 2013).
Real-time multi-fusion perceptron architecture for autonomous drones
Published in Journal of the Chinese Institute of Engineers, 2022
Basically, the fusion mode can be divided into three major types as shown in Figure 4. The first type is complementary fusion mode, in which the detection and recognition areas of heterogeneous sensors do not overlap, for example, a millimeter wave radar looking forward and another millimeter wave radar looking backward. It can be seen that each is responsible for a different sensing area, and such an arrangement can increase the overall sensing range of the system. The second type is competitive fusion mode, in which the detection ranges of heterogeneous sensors are the same to increase the reliability of the overall system detection and identification. The third type is cooperative fusion mode, in which the detection and recognition ranges of heterogeneous sensors still overlap, and those different sensors can provide the same or different physical descriptions of the subject to be sensed. In order for one sensor to complete the detection and recognition function, it must refer to the information provided by another sensor in addition to its own information. It can accelerate the speed and accuracy of detection and identification (Vu and You 2019; Chen et al. 2020).