scholarly journals Unmanned Surface Vehicle (USV) performance test in Bintan Island Waters

2021 ◽  
Vol 944 (1) ◽  
pp. 012013
Author(s):  
R Fauzi ◽  
I Jaya ◽  
M Iqbal
Keyword(s):  
Standard Deviation ◽  
Wind Speed ◽  
Water Surface ◽  
Performance Test ◽  
Average Frequency ◽  
Underwater Imaging ◽  
Unmanned Surface Vehicle ◽  
Unmanned Surface Vehicles ◽  
Vehicle Acceleration ◽  
Direction Of Movement

Abstract An unmanned surface vehicle (USV) is an unmanned vehicle that is operated on the surface of the water for certain purposes, for example, bathymetry measurement, underwater imaging, etc. These unmanned surface vehicles can be used in impassable waters for crewed vessels in dangerous waters. This research measures the movement of the vehicle acceleration and then calculates it as the USV roll and pitch values. The direction of movement and wind speed and the height of the water surface at low tide are also aspects measured in this research. An accelerometer is a sensor that can measure the acceleration of an object, both dynamic and static. Based on the observations, the highest roll value is 6.0° deep while the highest pitch value is 6.5°. The standard deviation value at roll conditions of 2.92 and the standard deviation value at pitch conditions of 1.25. The average frequency of roll conditions is 2.18 and pitch conditions of 1.13. The dominant wind moves from the south to the southwest with a dominant speed ranging from 3.0 to 4.0 m/s. The results of this research indicate that the USV has a good performance so that it is possible to collect data in the water.

PENGARUH MODEL PEMBELAJARAN KELILING KELOMPOK (ROUND CLUB) TERHADAP KETERAMPILAN MENULIS LAPORAN PERJALANAN SISWA KELAS V SDN 01 NAGARI BUKIK SIKUMPA

2020 ◽  
Author(s):  
Wirda Linda
Keyword(s):  
Standard Deviation ◽  
Performance Test ◽  
Writing Skills ◽  
Learning Model ◽  
Homogeneity Test ◽  
Test Results ◽  
Class V ◽  
Average Value ◽  
Normality Test ◽  
Lecture Method

This research is motivated by the low desire of students in writing travel reports. The lack of students' knowledge of the report concept, the lack of students' knowledge of the 5W + 1H report points of good and correct language, the lack of students' knowledge of the spatial, time and topic pattern and not yet reached KKM 75. The method used by the teacher has not been interesting, lecture method. The purpose of this study is to describe the skills of writing travel reports by using Round Club learning model which is viewed from the aspect of understanding the report concept, the use of 5W +1H report points, the spatial, time, and topic pattern.The population of this study is the students of class V Lessons Year 2017/2018 which amounted to 2 classes with the number 80. The sample of research as much as two classes taken by the sample of propotional.Class V.1 as experimental class and class V.2 as control class. The research instrument used is performance test. Provide an assessment by specifying the subject of the 5W + 1H report, as well as the spatial, time and topic pattern. Data were analyzed by 't' test by first testing normality, homogeneity, and hypothesis testing.The results showed that the average control class 68 with more than enough qualifications with standard deviation 16.96. 83 experimental class with good qualification and standard deviation of 15.42 and there is a significant influence on the result of writing skill of class V SDN 01 Nagari Bukik SikumpaSubdistrict, Lima Puluh Kota. This is evidenced by the average value of writing skills in the experiment class higher than the average value in the control class. Normality test results indicate that the two sample classes of  Lo  values in the control class -0.2141 are smaller than the normal 0.190 Lt distributed. Homogeneity test results that the variation of this study is homogeneous at a real level of 0.05, because Ftable 2.16 > Fhitung 1.21 and the results of data analysis then obtained = 2.78 > 1.70 t table, so H0 rejected and H1 accepted. It can be concluded that there is Influence. Using  Learning  Model of Student Group Writing  Skills Travel Report of students of class V SDN 01 Nagari Bukik Sikumpa Subdistrict, Kabupaten Lima Puluh Kota.KeyWords: model pembelajaran round club, menulis laporan perjalanan.

scholarly journals The super-turbine wind power conversion paradox: using machine learning to reduce errors caused by Jensen's inequality

2019 ◽  
Vol 4 (2) ◽  
pp. 343-353 ◽  
Author(s):  
Tyler C. McCandless ◽  
Sue Ellen Haupt
Keyword(s):  
Machine Learning ◽  
Standard Deviation ◽  
Wind Speed ◽  
Wind Power ◽  
Power Conversion ◽  
Jensen’S Inequality ◽  
Jensen's Inequality ◽  
Average Wind Speed ◽  
Wind Speeds ◽  
Average Wind

Abstract. Wind power is a variable generation resource and therefore requires accurate forecasts to enable integration into the electric grid. Generally, the wind speed is forecast for a wind plant and the forecasted wind speed is converted to power to provide an estimate of the expected generating capacity of the plant. The average wind speed forecast for the plant is a function of the underlying meteorological phenomena being predicted; however, the wind speed for each turbine at the farm is also a function of the local terrain and the array orientation. Conversion algorithms that assume an average wind speed for the plant, i.e., the super-turbine power conversion, assume that the effects of the local terrain and array orientation are insignificant in producing variability in the wind speeds across the turbines at the farm. Here, we quantify the differences in converting wind speed to power at the turbine level compared with a super-turbine power conversion for a hypothetical wind farm of 100 2 MW turbines as well as from empirical data. The simulations with simulated turbines show a maximum difference of approximately 3 % at 11 m s−1 with a 1 m s−1 standard deviation of wind speeds and 8 % at 11 m s−1 with a 2 m s−1 standard deviation of wind speeds as a consequence of Jensen's inequality. The empirical analysis shows similar results with mean differences between converted wind speed to power and measured power of approximately 68 kW per 2 MW turbine. However, using a random forest machine learning method to convert to power reduces the error in the wind speed to power conversion when given the predictors that quantify the differences due to Jensen's inequality. These significant differences can lead to wind power forecasters overestimating the wind generation when utilizing a super-turbine power conversion for high wind speeds, and indicate that power conversion is more accurately done at the turbine level if no other compensatory mechanism is used to account for Jensen's inequality.

Prediction of the Standard Deviation of Wind Speed Turbulence

2018 ◽  
Author(s):  
G. R. Ren ◽  
◽  
J. F. Liu ◽  
J. Wan ◽  
Q. H. Hu ◽  
...  
Keyword(s):  
Standard Deviation ◽  
Wind Speed

scholarly journals Comparison Of Three Numerical Methods For Estimating Weibull Parameters Using Weibull Distribution Model In Nigeria

2020 ◽  
Vol 27 (2) ◽  
pp. 8-15
Author(s):  
J.A. Oyewole ◽  
F.O. Aweda ◽  
D. Oni
Keyword(s):  
Standard Deviation ◽  
Wind Speed ◽  
Probability Density Function ◽  
Weibull Distribution ◽  
Probability Density ◽  
Density Function ◽  
Accurate Estimation ◽  
Weibull Parameters ◽  
Factor Method ◽  
Deviation Method

There is a crucial need in Nigeria to enhance the development of wind technology in order to boost our energy supply. Adequate knowledge about the wind speed distribution becomes very essential in the establishment of Wind Energy Conversion Systems (WECS). Weibull Probability Density Function (PDF) with two parameters is widely accepted and is commonly used for modelling, characterizing and predicting wind resource and wind power, as well as assessing optimum performance of WECS. Therefore, it is paramount to precisely estimate the scale and shape parameters for all regions or sites of interest. Here, wind data from year 2000 to 2010 for four different locations (Port Harcourt, Ikeja, Kano and Jos) were analysed and the Weibull parameters was determined. The three methods employed are Mean Standard Deviation Method (MSDM), Energy Pattern Factor Method (EPFM) and Method of Moments (MOM) for estimating Weibull parameters. The method that gave the most accurate estimation of the wind speed was MSDM method, while Energy Pattern Factor Method (EPFM) is the most reliable and consistent method for estimating probability density function of wind. Keywords: Weibull Distribution, Method of Moment, Mean Standard Deviation Method, Energy Pattern Method

scholarly journals Development of Hardware-in-the-Loop-Simulation Testbed for Pitch Control System Performance Test

Energies ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 2031
Author(s):  
Jongmin Cheon ◽  
Jinwook Kim ◽  
Joohoon Lee ◽  
Kichang Lee ◽  
Youngkiu Choi
Keyword(s):  
Control System ◽  
Wind Speed ◽  
Wind Turbine ◽  
Wind Shear ◽  
Performance Test ◽  
Control Function ◽  
Hardware In The Loop ◽  
Rotor Speed ◽  
Test Bed ◽  
Pitch Control

This paper deals with the development of a wind turbine pitch control system and the construction of a Hardware-in-the-Loop-Simulation (HILS) testbed for the performance test of the pitch control system. When the wind speed exceeds the rated wind speed, the wind turbine pitch controller adjusts the blade pitch angles collectively to ensure that the rotor speed maintains the rated rotor speed. The pitch controller with the individual pitch control function can add individual pitch angles into the collective pitch angles to reduce the mechanical load applied to the blade periodically due to wind shear. Large wind turbines often experience mechanical loads caused by wind shear phenomena. To verify the performance of the pitch control system before applying it to an actual wind turbine, the pitch control system is tested on the HILS testbed, which acts like an actual wind turbine system. The testbed for evaluating the developed pitch control system consists of the pitch control system, a real-time unit for simulating the wind and the operations of the wind turbine, an operational computer with a human–machine interface, a load system for simulating the actual wind load applied to each blade, and a real pitch bearing. Through the several tests based on HILS test bed, how well the pitch controller performed the given roles for each area in the entire wind speed area from cut-in to cut-out wind speed can be shown.

scholarly journals The Transition from Downward to Upward Air–Sea Momentum Flux in Swell-Dominated Light Wind Conditions

2018 ◽  
Vol 75 (8) ◽  
pp. 2579-2588 ◽  
Author(s):  
Ulf Högström ◽  
Erik Sahlée ◽  
Ann-Sofi Smedman ◽  
Anna Rutgersson ◽  
Erik Nilsson ◽  
...  
Keyword(s):  
Wind Speed ◽  
Momentum Flux ◽  
Water Surface ◽  
Sea Waves ◽  
Progressive Wave ◽  
Wind Speeds ◽  
Low Wind Speed ◽  
Light Wind ◽  
Wind Sea ◽  
Almost All

Abstract Fifteen hours of consecutive swell data from the experiment Flux, État de la Mer, et Télédétection en Condition de Fetch Variable (FETCH) in the Mediterranean show a distinct upward momentum flux. The characteristics are shown to vary systematically with wind speed. A hysteresis effect is found for wave energy of the wind-sea waves when represented as a function of wind speed, displaying higher energy during decaying winds compared to increasing winds. For the FETCH measurements, the upward momentum transfer regime is found to begin for wind speeds lower than about U = 4 m s−1. For the lowest observed wind speeds U < 2.4 m s−1, the water surface appears to be close to dynamically smooth. In this range almost all the upward momentum flux is accomplished by the peak in the cospectrum between the vertical and horizontal components of the wind velocity. It is demonstrated that this contribution in turn is linearly related to the swell significant wave height Hsd in the range 0.6 < Hsd < 1.4 m. For Hsd < 0.6 m, the contribution is zero in the present dataset but may depend on the swell magnitude in other situations. It is speculated that the observed upward momentum flux in the smooth regime, which is so strongly related to the cospectral peak at the dominant swell frequency, might be caused by the recirculation mechanism found by Wen and Mobbs in their numerical simulation of laminar flow of a nonlinear progressive wave at low wind speed.

The aerodynamic drag of a free water surface

1951 ◽  
Vol 206 (1086) ◽  
pp. 387-406 ◽  
Keyword(s):  
Shear Stress ◽  
Wind Speed ◽  
Water Surface ◽  
Aerodynamic Drag ◽  
Free Water ◽  
Large Field ◽  
Rough Boundary ◽  
Anomalous Zone ◽  
Stress Coefficient ◽  
The Waves

The drag exerted by wind on a water surface has been measured in a tunnel 7·5 cm. wide and 7 m. long in which winds up to 14 m. /sec. can be made. The waves thus formed are similar to those seen at sea. A device increases the effective fetch and therefore the size of the waves. The drag is measured by the slope of the mean water surface. The shear-stress coefficient γ 2 a = τ / ρu 2 a increases nearly linearly with wind speed, and the drag therefore increases nearly with the cube of the speed. There is a not unsatisfactory agreement with field results of shear coefficient, when the wind velocity is extrapolated to the greater height at which it is usually measured over the sea. It is thought that this agreement between the drag of small laboratory waves and large field waves may show that the mechanism for drag is not controlled by the wave size or speed, but perhaps by the tiny wind ripples. The variation of wind speed with height has been measured. The profiles sometimes show anomalies in the zone up to about 8 cm. above the crests, there being slow layers of air between faster ones. The height of the anomalous zone increases as the waves become higher. Above 8 cm. the usual rough boundary law holds good. An empirical law is given for the shear stress as a function of the speed of the surface layer of water.

Mechanoreceptor and Photoreceptor Tonic Integration in the Crayfish

1973 ◽  
Vol 51 (12) ◽  
pp. 949-958 ◽  
Author(s):  
C. Galeano ◽  
S. Beliveau
Keyword(s):  
Statistical Analysis ◽  
Standard Deviation ◽  
Coefficient Of Variation ◽  
Average Frequency ◽  
Ipsilateral Side ◽  
Average Interval ◽  
Caudal Photoreceptor ◽  
Deviation Coefficient ◽  
Variation Interval ◽  
Density Results

The activity of the caudal photoreceptor of crayfish was studied in: (1) intact tail ganglion, (2) partially isolated, and (3) totally isolated ganglion preparations. Statistical analysis of the photoreceptor activity included average frequency, average interval, variance, standard deviation, coefficient of variation, interval histograms, auto-expectation density, and cross-expectation density. Results showed that the average influence of the mechanoreceptor synapses on the photoreceptors during a period of several seconds was inhibitory, strong on the contralateral and weak on the ipsilateral side.

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