scholarly journals Coherent detection-based photonic radar for autonomous vehicles under diverse weather conditions

PLoS ONE ◽  
2021 ◽  
Vol 16 (11) ◽  
pp. e0259438
Author(s):  
Sushank Chaudhary ◽  
Lunchakorn Wuttisittikulkij ◽  
Muhammad Saadi ◽  
Abhishek Sharma ◽  
Sattam Al Otaibi ◽  
...  
Keyword(s):  
Autonomous Vehicles ◽  
Signal To Noise Ratio ◽  
Weather Conditions ◽  
Coherent Detection ◽  
Limited Bandwidth ◽  
Received Power ◽  
Sweep Time ◽  
Bad Weather ◽  
The Impact ◽  
Target Locations

Autonomous vehicles are regarded as future transport mechanisms that drive the vehicles without the need of drivers. The photonic-based radar technology is a promising candidate for delivering attractive applications to autonomous vehicles such as self-parking assistance, navigation, recognition of traffic environment, etc. Alternatively, microwave radars are not able to meet the demand of next-generation autonomous vehicles due to its limited bandwidth availability. Moreover, the performance of microwave radars is limited by atmospheric fluctuation which causes severe attenuation at higher frequencies. In this work, we have developed coherent-based frequency-modulated photonic radar to detect target locations with longer distance. Furthermore, the performance of the proposed photonic radar is investigated under the impact of various atmospheric weather conditions, particularly fog and rain. The reported results show the achievement of significant signal to noise ratio (SNR) and received power of reflected echoes from the target for the proposed photonic radar under the influence of bad weather conditions. Moreover, a conventional radar is designed to establish the effectiveness of the proposed photonic radar by considering similar parameters such as frequency and sweep time.

Modelling of 10 Gbps Free Space Optics Communication Link Using Array of Receivers in Moderate and Harsh Weather Conditions

2017 ◽  
Vol 38 (3) ◽  
Author(s):  
Amit Gupta ◽  
Nagpal Shaina
Keyword(s):  
Free Space ◽  
Weather Conditions ◽  
Quality Data ◽  
Laser Source ◽  
Communication Link ◽  
Free Space Optical ◽  
Space Optics ◽  
Received Power ◽  
Adverse Weather ◽  
The Impact

AbstractIntersymbol interference and attenuation of signal are two major parameters affecting the quality of transmission in Free Space Optical (FSO) Communication link. In this paper, the impact of these parameters on FSO communication link is analysed for delivering high-quality data transmission. The performance of the link is investigated under the influence of amplifier in the link. The performance parameters of the link like minimum bit error rate, received signal power and Quality factor are examined by employing erbium-doped fibre amplifier in the link. The effects of amplifier are visualized with the amount of received power. Further, the link is simulated for moderate weather conditions at various attenuation levels on transmitted signal. Finally, the designed link is analysed in adverse weather conditions by using high-power laser source for optimum performance.

scholarly journals The Erika Oil Spill: The Bird Rescue Response

2001 ◽  
Vol 2001 (1) ◽  
pp. 737-744
Author(s):  
André Lamy ◽  
Jean Pierre Jacques ◽  
Sophie Le Dréan-Quénec'hdu
Keyword(s):  
Weather Conditions ◽  
Natural Environments ◽  
Medical Studies ◽  
Emergency Plan ◽  
Emergency Response Plan ◽  
First Results ◽  
Veterinary School ◽  
Bad Weather ◽  
The Impact ◽  
Medical Material

ABSTRACT On December 12, 1999, the 30,000-ton tanker Erika broke apart 100 km off the coast of Brittany, one of Europe's most pristine natural environments. France immediately launched a prepared countermeasure, the Polmar plan, designed to minimize the impact of the disaster on the sea and shore. In spite of the relatively small amount of fuel released, the location of the spill in high seas and the bad weather conditions caused the pollution to spread widely along the coastline over a number of weeks. Wildlife centers were mobilized to handle the anticipated load of 1,000 oiled birds. In the end, more than 15,000 birds were captured alive. The sea birds impacted were mainly guillemots and, to a lesser extent, scoters and gannets. TotalFinaElf helped the triage centers by providing finances, medical material, water-heating facilities, and several automated bird-washing devices with specialized detergent. The group funds the medical studies undertaken on the oiled birds in the triage center of the National Veterinary School (ENV) of Nantes. It also works in partnership with the French National Bird Rescue Association to improve the emergency response plan by defining their needs in terms of equipment and to provide a consensual “oiled-bird caring protocol” manual. This report will both assess the existing response program by detailing the chronological implementation of the emergency plan for the oiled birds and present the first results of the medical studies undertaken. It will detail the types of birds impacted, the methods by which they were cured and cleaned, an analysis of their condition, the efforts made to improve the treatments, and, most importantly, the medical questions raised by such a situation.

scholarly journals The impact of different saturation headway values on intersection capacity

2021 ◽  
Author(s):  
Dražen Cvitanić ◽  
Biljana Maljković
Keyword(s):  
Traffic Flow ◽  
Flow Structure ◽  
Road Network ◽  
Weather Conditions ◽  
Traffic Volume ◽  
Signalized Intersections ◽  
Signal Timing ◽  
Bad Weather ◽  
The Impact ◽  
The City

Elements of the city road network that determine its capacity are signalized intersections. Their capacity depends of many factors: traffic volume and distribution, traffic flow structure, signal timing, and number of bicyclists and pedestrians. However, the starting parameter for calculation of intersection capacity is saturation headway. This research explores the influence of weather conditions and purpose of trip on saturation headway. Saturation headways were determined on few intersections in the morning peak hour of working and weekend day, in good and bad weather conditions. The impact of different trip purposes and different weather conditions on intersection capacity is analysed, as well as the influence of using mean and median values of saturation headway when calculating the intersection capacity.

ASSESSMENT OF TARGET DETECTION ABILITY FOR LASER FUZES IN FOG CONDITIONS

2021 ◽  
pp. 8-16
Author(s):  
Linh
Keyword(s):  
Target Detection ◽  
Detection Probability ◽  
Detection Efficiency ◽  
Signal To Noise Ratio ◽  
Evaluation Model ◽  
Laser System ◽  
Weather Conditions ◽  
Signal To Noise ◽  
Detection Ability ◽  
Bad Weather

The article presents a method to evaluate the target detection efficiency of laser fuzes operating in foggy conditions. The evaluation model is built from: the distance equation of the laser system, the attenuation of the beam in two-way propagation, the disturbances affecting the system; the signal to noise ratio SRN has determined the detection probability of the receiver. The model was used to evaluate with wavelengths: 850 nm, 1000 nm and 1550 nm, when propagating in three different bad weather conditions. The results show that the most effective detection of the target when using a wavelength of 1550 nm in visibility in haze and mist conditions (visibility V > 500 m). In fog conditions (visibility V < 500 m), the above three wavelengths provide the same detection efficiency. The article provides the method and instructions for choosing the wavelength of the laser fuze.

scholarly journals A Cost-Effective Photonic Radar Under Adverse Weather Conditions for Autonomous Vehicles by Incorporating a Frequency-Modulated Direct Detection Scheme

2021 ◽  
Vol 9 ◽  
Author(s):  
Abhishek Sharma ◽  
Sushank Chaudhary ◽  
Jyoteesh Malhotra ◽  
Muhammad Saadi ◽  
Sattam Al Otaibi ◽  
...  
Keyword(s):  
Autonomous Vehicles ◽  
Direct Detection ◽  
Signal To Noise Ratio ◽  
Autonomous Vehicle ◽  
Cost Effective ◽  
Weather Conditions ◽  
Atmospheric Conditions ◽  
Detection Scheme ◽  
Available Bandwidth ◽  
Adverse Weather

In recent years, there have been plenty of demands and growth in the autonomous vehicle industry, and thus, challenges of designing highly efficient photonic radars that can detect and range any target with the resolution of a few centimeters have been encountered. The existing radar technology is unable to meet such requirements due to limitations on available bandwidth. Another issue is to consider strong attenuation while working under diverse atmospheric conditions at higher frequencies. The proposed model of photonic radar is developed considering these requirements and challenges using the frequency-modulated direct detection technique and considering a free-space range of 750 m. The result depicts improved range detection in terms of received power and an acceptable signal-to-noise ratio and range under adverse climatic situations.

scholarly journals Pogodowe uwarunkowania działań wojennych. Wpływ warunków atmosferycznych na przebieg starć i kampanii militarnych w okresie średniowiecza. Wybrane przykłady

2020 ◽  
Author(s):  
Andrzej Niewiński
Keyword(s):  
Disease Outbreaks ◽  
Temperature Fluctuations ◽  
Weather Conditions ◽  
Military Operation ◽  
Adverse Weather Conditions ◽  
Adverse Weather ◽  
Medieval Chronicles ◽  
Military Campaigns ◽  
Bad Weather ◽  
The Impact

The article examines the impact of adverse weather conditions and astronomical occurrences on the outcome of the selected medieval military campaigns and pitch battles. Unpredictability of weather was an important factor in medieval warfare: unexpected wind, rain, snow, heat or day-to-night temperature fluctuations could influence a military operation in a significant way. As medieval chronicles recorded, troops often suffered from famine as a result of excessive rains, droughts or adverse winds which prevented supplies from being delivered by sea. Apart from causing fatigue and exhaustion bad weather contributed to disease outbreaks and equipment damage. People were weakened physically and psychologically which reduced their fighting ability.

scholarly journals Impact of Chirp in High-Capacity Optical Metro Networks Employing Directly-Modulated VCSELs

Photonics ◽  
2018 ◽  
Vol 5 (4) ◽  
pp. 51 ◽  
Author(s):  
Mariangela Rapisarda ◽  
Alberto Gatto ◽  
Paolo Martelli ◽  
Paola Parolari ◽  
Christian Neumeyr ◽  
...  
Keyword(s):  
Signal To Noise Ratio ◽  
High Capacity ◽  
Optical Signal ◽  
Coherent Detection ◽  
Cavity Surface ◽  
Micro Electro Mechanical Systems ◽  
Discrete Multitone ◽  
Long Wavelength ◽  
Emitting Lasers ◽  
The Impact

Directly modulated long-wavelength vertical cavity surface emitting lasers (VCSELs) are considered for the implementation of sliceable bandwidth/bitrate variable transceivers for very high capacity transmission (higher than 50 Gb/s per wavelength) in metropolitan area systems characterized by reduced cost, power consumption, and footprint. The impact of the frequency chirp measured for InP VCSELs with different kinds of design (high-bandwidth very short cavity and widely-tunable with micro electro-mechanical systems (MEMS) top mirror) is analyzed in case of discrete multitone (DMT) direct modulation in combination with 25-GHz wavelength selective switch (WSS) filtering. The maximum transmitted capacity for both dual side- and single side-band DMT modulation is evaluated as a function of the number of crossed nodes in a mesh metro network, comparing VCSEL based transmitters performance also with the case of external electro-absorption modulator use. Finally, the maximum reach achieved based on the received optical signal to noise ratio (OSNR) and the fiber span length is discussed. The results confirm the possibility to use directly-modulated long-wavelength VCSELs for the realization of sliceable bandwidth/bitrate variable transmitters targeting 50-Gb/s capacity per polarization, also in the presence of 5 crossed WSSs for reaches of hundreds of kilometers in multi-span Erbium-doped fiber amplified (EDFA) metro links supported by coherent detection.

The Impact of Adverse Weather Conditions on Autonomous Vehicles: How Rain, Snow, Fog, and Hail Affect the Performance of a Self-Driving Car

2019 ◽  
Vol 14 (2) ◽  
pp. 103-111 ◽  
Author(s):  
Shizhe Zang ◽  
Ming Ding ◽  
David Smith ◽  
Paul Tyler ◽  
Thierry Rakotoarivelo ◽  
...  
Keyword(s):  
Autonomous Vehicles ◽  
Weather Conditions ◽  
Adverse Weather Conditions ◽  
Adverse Weather ◽  
The Impact

scholarly journals Bandwidth and BER Improvement Employing a Pre-Equalization Circuit with White LED Arrays in a MISO VLC System

2019 ◽  
Vol 9 (5) ◽  
pp. 986 ◽  
Author(s):  
Monette Khadr ◽  
Ahmed Abd El Aziz ◽  
Heba Fayed ◽  
Moustafa Aly
Keyword(s):  
Signal To Noise Ratio ◽  
Visible Light Communication ◽  
Bandwidth Extension ◽  
Bandwidth Enhancement ◽  
White Leds ◽  
Limited Bandwidth ◽  
Single Output ◽  
Data Rates ◽  
The Impact ◽  
Led Arrays

This paper aims to extend the limited bandwidth of phosphorescent white LEDs for a multiple-input single-output (MISO) visible light communication (VLC) system. A proposed LED arrangement model is presented, resulting in improved results as compared to those previously discussed in the literature. In this paper, the impact of the receiver field of view (FOV) angle, the LED transmission angle, and the number of LED arrays used on the transmission are studied at different speeds. The system performance is measured by the signal to noise ratio (SNR) and the corresponding bit error rate (BER) at different data rates. The obtained results show that the proposed model is able to improve the illumination uniformity across the room with a higher SNR using the same number of LEDs in the investigated indoor environment. The paper also introduces a pre-equalization circuit in the transmitter end in order to extend the limited bandwidth of the used white LEDs. This bandwidth extension using the proposed circuit results in an increased data rate with the aid of a blue filter. A number of experiments are executed to optimize the key parameters for maximum bandwidth enhancement. The proposed circuit offers 28% bandwidth enhancement over the most recent study in this area while eradicating the BER at 200 Mb/s when compared to un-equalized LED circuits.

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