scholarly journals Research and Development of a Transportable Optical Ground Station in NICT: The Results of the First Performance Test

2021 ◽  
Vol 9 ◽  
Author(s):  
Yoshihiko Saito ◽  
Hideki Takenaka ◽  
Koichi Shiratama ◽  
Yasushi Munemasa ◽  
Alberto Carrasco-Casado ◽  
...  
Keyword(s):  
High Speed ◽  
Performance Test ◽  
The Other ◽  
Atmospheric Conditions ◽  
Free Space Optical ◽  
Ground Station ◽  
Pointing Accuracy ◽  
Set Up ◽  
Site Diversity ◽  
Diversity Technique

In recent years, the necessity of free-space optical (FSO) communications has increased as a method for realizing high-speed communications between satellites and the ground. However, one disadvantage of FSO communications is the significant influence of the atmosphere. Specifically, FSO communications cannot be utilized under certain atmospheric conditions, especially in the presence of clouds. One of the solutions to this problem is the site diversity technique, which makes it possible to select a given ground station with better atmospheric conditions among a number of fixed ground stations. The other solution is to prepare a ground station that can be moved to a place with better atmospheric conditions. We applied the latter method and developed a transportable optical ground station in NICT. We utilize a realistic telescope diameter, which is about 30 cm at the maximum, capable of being set up quickly, and with a pointing accuracy of about 100 µrad. In addition, it is necessary to prepare a fine-pointing optical system that performs tracking with about 1/10 of the pointing accuracy of the telescope. In this paper, we report the results of the first performance test of the transportable optical ground station in NICT.

A Survey on Internet of Vehicles Applications, Architecture, Communication Models and Challenges

2021 ◽  
Vol 13 (4) ◽  
Author(s):  
Xuemei Hu ◽  
Huiying Wu
Keyword(s):  
Electric Vehicle ◽  
High Speed ◽  
Performance Test ◽  
High Efficiency ◽  
Transmission Efficiency ◽  
Internet Of Vehicles ◽  
Communication Models ◽  
Drive Motor ◽  
Set Up ◽  
Shift Speed

To solve the problems of long shifting time and low transmission efficiency of motor transmission in unmanned electric vehicles, the performance test of motor transmission is carried out. The EMT transmission system is selected as the test object of the motor transmission of an unmanned electric vehicle. The gear number of the transmission is determined with the aim of reducing the speed requirement of the motor when the motor runs at high speed and working in the high-efficiency area near the base speed as far as possible. According to the gear speed and torque of the load motor, the driving moment and torsion moment of the drive motor in the acceleration stage are determined based on the total inertia of the drive motor and other parameters. Finally, the test bench of the motor transmission towing is set up and the test is carried out. The experimental results show that when the rated torque of the motor transmission is 100% at 1600r/min shift speed point and 150% at 1800r/min shift speed point, the minimum shift time of the motor transmission is 425ms. Meanwhile, the transmission efficiency of the motor transmission of the unmanned electric vehicle is between 90% and 92% and the transmission performance is high.

scholarly journals From Mirrors to Free-Space Optical Communication—Historical Aspects in Data Transmission

2020 ◽  
Vol 12 (11) ◽  
pp. 179
Author(s):  
Magdalena Garlinska ◽  
Agnieszka Pregowska ◽  
Karol Masztalerz ◽  
Magdalena Osial
Keyword(s):  
Optical Communication ◽  
Data Transmission ◽  
Free Space ◽  
Communication Systems ◽  
High Speed ◽  
Rapid Development ◽  
Free Space Optical Communication ◽  
Atmospheric Conditions ◽  
Free Space Optical ◽  
Space Optical Communication

Fast communication is of high importance. Recently, increased data demand and crowded radio frequency spectrum have become crucial issues. Free-Space Optical Communication (FSOC) has diametrically changed the way people exchange information. As an alternative to wire communication systems, it allows efficient voice, video, and data transmission using a medium like air. Due to its large bandwidth, FSOC can be used in various applications and has therefore become an important part of our everyday life. The main advantages of FSOC are a high speed, cost savings, compact structures, low power, energy efficiency, a maximal transfer capacity, and applicability. The rapid development of the high-speed connection technology allows one to reduce the repair downtime and gives the ability to quickly establish a backup network in an emergency. Unfortunately, FSOC is susceptible to disruption due to atmospheric conditions or direct sunlight. Here, we briefly discuss Free-Space Optical Communication from mirrors and optical telegraphs to modern wireless systems and outline the future development directions of optical communication.

scholarly journals Assessment of FOG and Rain Induced-Attenuation on Terrestrial FSO Links

2019 ◽  
Vol 4 (1) ◽  
pp. 37-44
Author(s):  
Ajewole , M. O. ◽  
Owolawi , P. A. ◽  
Adetunji , R. M.
Keyword(s):  
Communication Systems ◽  
High Speed ◽  
Rain Rate ◽  
Outer Space ◽  
Integration Time ◽  
Expert Committee ◽  
Rate Data ◽  
Atmospheric Conditions ◽  
Free Space Optical ◽  
Wireless Communication Network

Notice of Retraction-----------------------------------------------------------------------After careful and considered review of the content of this paper by a duly constituted expert committee, this paper has been found to be in violation of APTIKOM's Publication Principles.We hereby retract the content of this paper. Reasonable effort should be made to remove all past references to this paper.The presenting author of this paper has the option to appeal this decision by contacting ij.aptikom@gmail.com.-----------------------------------------------------------------------  Launching into the next generation of wireless communication network (5G network) requires secure high data rate, high speed and huge bandwidth links. With the tremendous increase in broadband users, the existing communication systems such as radio frequency (RF) and microwave links cannot meet up with the challenges due to their link interference and low bandwidth. A current technology that promises such requirements and more is Free Space Optical (FSO) communication. The FSO basically involves the transmission of signal-modulated optical radiation from a transmitter to a receiver through the atmosphere or outer space. It is designed to complement the traditional fibre optical communication links. However, location-variant atmospheric channel degrades the quality and performance of an FSO system under severe atmospheric conditions. This paper attempts to assess both fog- and rain-induced attenuation on the performance of FSO link in a terrestrial terrain using measured visibility and rain rate data at Akure, Nigeria. 5-year (2012-2016) archived visibility data and measured rain rate data of 1-minute integration time obtained from Nigerian Meteorological Agency (NIMET) and the Department of Physics, Federal University of Technology, Akure respectively, were used to compute the fog- and rain-induced specific attenuations using Kruse and Carboneur models. The performance of the FSO system was analyzed through link margin by using the parameters of a commercial optical transceiver, Terescope 5000. Findings from this work will be useful for FSO system design in the area.

scholarly journals Assessment of fog and rain induced-attenuation on terrestrial FSO links

2019 ◽  
Vol 4 (3) ◽  
Author(s):  
M. O. Ajewole
Keyword(s):  
Communication Systems ◽  
High Speed ◽  
Rain Rate ◽  
Outer Space ◽  
Integration Time ◽  
Rate Data ◽  
Atmospheric Conditions ◽  
Free Space Optical ◽  
High Data ◽  
Wireless Communication Network

 Launching into the next generation of wireless communication network (5G network) requires secure high data rate, high speed and huge bandwidth links. With the tremendous increase in broadband users, the existing communication systems such as radio frequency (RF) and microwave links cannot meet up with the challenges due to their link interference and low bandwidth. A current technology that promises such requirements and more is Free Space Optical (FSO) communication. The FSO basically involves the transmission of signal-modulated optical radiation from a transmitter to a receiver through the atmosphere or outer space. It is designed to complement the traditional fibre optical communication links. However, location-variant atmospheric channel degrades the quality and performance of an FSO system under severe atmospheric conditions. This paper attempts to assess both fog- and rain-induced attenuation on the performance of FSO link in a terrestrial terrain using measured visibility and rain rate data at Akure, Nigeria. 5-year (2012-2016) archived visibility data and measured rain rate data of 1-minute integration time obtained from Nigerian Meteorological Agency (NIMET) and the Department of Physics, Federal University of Technology, Akure respectively, were used to compute the fog- and rain-induced specific attenuations using Kruse and Carboneur models. The performance of the FSO system was analyzed through link margin by using the parameters of a commercial optical transceiver, Terescope 5000. Findings from this work will be useful for FSO system design in the area.

Whipping instability characterization of an electrified visco-capillary jet

2011 ◽  
Vol 671 ◽  
pp. 226-253 ◽  
Author(s):  
GUILLAUME RIBOUX ◽  
ÁLVARO G. MARÍN ◽  
IGNACIO G. LOSCERTALES ◽  
ANTONIO BARRERO
Keyword(s):  
High Speed ◽  
Dielectric Liquid ◽  
Taylor Cone ◽  
The Other ◽  
Experimental Characterization ◽  
Dimensionless Numbers ◽  
Host Medium ◽  
Set Up ◽  
Axisymmetric Instability

The charged liquid micro-jet issued from a Taylor cone may develop a special type of non-axisymmetric instability, usually referred to in the literature as a whipping mode. This instability usually manifests itself as a series of fast and violent lashes of the charged jet, which makes its characterization in the laboratory difficult. Recently, we have found that this instability may also develop when the host medium surrounding the Taylor cone and the jet is a dielectric liquid instead of air. When the oscillations of the jet occur inside a dielectric liquid, their frequency and amplitude are much lower than those of the oscillations taking place in air. Taking advantage of this fact, we have performed a detailed experimental characterization of the whipping instability of a charged micro-jet within a dielectric liquid by recording the jet motion with a high-speed camera. Appropriate image processing yields the frequency and wavelength, among the other important characteristics, of the jet whipping as a function of the governing parameters of the experimental set-up (flow rate and applied electric field) and liquid properties. Alternatively, the results can be also written as a function of three dimensionless numbers: the capillary and electrical Bond numbers and the ratio between an electrical relaxation and residence time.

Choose you own scientific experiment: Triggering debris flows and flash floods

2016 ◽  
Author(s):  
Thea Turkington
Keyword(s):  
Debris Flows ◽  
Flash Floods ◽  
The Other ◽  
Background Information ◽  
Atmospheric Conditions ◽  
Scientific Experiment

Landslides and flash floods result in many fatalities around the globe. Understanding what triggers these events is therefore vital, although how to approach this problem is not straight forward. After background information for the experiment and some guidelines, two options are presented to learn more about the triggers of debris flows: (A) using rainfall or (B) the atmospheric conditions. You can then choose the option that appears more useful and interesting to you (you can always go back and read the other experiment afterwards). The article then ends with a reflection on the results.

Annual Variability in Summer Evapotranspiration and Water Balance at a Subarctic Forest Site

1994 ◽  
Vol 25 (5) ◽  
pp. 331-344 ◽  
Author(s):  
Peter M. Lafleur
Keyword(s):  
Water Balance ◽  
Daily Precipitation ◽  
The Other ◽  
Forest Site ◽  
Net Radiation ◽  
Atmospheric Conditions ◽  
Surface Moisture ◽  
Equilibrium Evaporation ◽  
Subarctic Forest ◽  
Single Regression

Evapotranspiration (ET) and precipitation were measured during five summers (1989-1993 inclusive) at a subarctic forest site near Churchill, Manitoba, Canada. Mean daily ET varied from 2.14-3.18 mm d−1 during the five summers, while mean daily precipitation (P) ranged from 1.46-3.15 mm d−1. Yearly variability in summer ET was most influenced by availability of surface moisture, then by atmospheric conditions (i.e. temperature), and least of all by net radiation. In four of the five years total summer ET exceeded P resulting in significant soil water deficits and in the other year summer ET and P were similar in magnitude. The use of equilibrium evaporation (EE) as a predictor of ET was explored. Separate relationships between ET and EE were computed for all five years. Three statistically dissimilar groups of equations were found: 1989/1990, 1991/ 1992, and 1993. A single regression equation describing all years is presented.

THEORY OF DETECTION OF HIGH-SPEED POINT TYPE OBJECTS UPON CHANGING ATMOSPHERIC CONDITIONS

2017 ◽  
Author(s):  
R. N. Abdulov ◽  
◽  
N. A. Abdullaev ◽  
Kh. G. Asadov ◽  
◽  
...  
Keyword(s):  
High Speed ◽  
Atmospheric Conditions ◽  
Point Type

Doctrine and Dialectic in Plato’s Dialogues

2018 ◽  
Author(s):  
Rachana Kamtekar
Keyword(s):  
Methodological Approach ◽  
The Other ◽  
Set Up

Chapter 1 lays out the methodological approach employed throughout the book, which is to pay attention to the dialectical dependence of what the main speaker in the dialogue says on the intellectual problem(s) set up in the dialogue both by himself and the other speakers. To illustrate, Chapter 1 describes Socrates’ use of the method of hypotheses from the Meno and Phaedo to answer questions that go beyond his claims to knowledge in the Republic.

scholarly journals Preparation of alcohol-based handrub in COVID-19 Alsatian cluster

2020 ◽  
Vol 5 (1) ◽  
Author(s):  
Elodie Di-Falco ◽  
Johan Bourbon ◽  
Isalyne Sbaffe ◽  
Jean-Daniel Kaiser
Keyword(s):  
Critical Period ◽  
Hospital Management ◽  
Management Team ◽  
The Other ◽  
Packaging Materials ◽  
Local Production ◽  
Technical Grade ◽  
Hand Sanitizer ◽  
Set Up ◽  
Real Challenge

AbstractAlsace, in particular Haut-Rhin, is one of the main clusters of COVID-19 in France. There has been a shortage of essential supplies in the area, especially alcohol-based hand sanitizer. In this context, and in accordance with the decree dated March 6, 2020, our hospital management team asked us to start local production of alcohol-based handrub. This was a real challenge: In one week, we had to implement the production of handrub to meet the needs of a 1,400-bed hospital. The production had to comply with the French preparation guidelines and take place on specific premises, with qualified and calibrated equipment, by qualified staff, under the supervision of a pharmacist. The other big challenge we faced was the supply of pharmaceutical raw and packaging materials. During this particular critical period, all suppliers were out of stock. Here, we describe the organizational set-up and the decisions made, e. g., to use technical-grade ethanol before the publication of the decrees dated March 13 and March 23, 2020.

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