Calibration of the Azimuth Drive Angle Sensor of the Mobile Automated Astronomical System by Stars Observation

The paper describes the design of the mobile automated astronomical system (MAAS) and the technique of the MAAS azimuth drive calibration by the zenithal stars observation. This technique provides fast and accurate calibration of the MAAS azimuth drive angle sensor in field conditions.

Experimental Study of Nuclear Gyro Bias Compensation Using the Quality Factor Estimation

The possibility for bias compensation of nuclear gyro using the quality factor estimation is shown. The corresponding method is described. A description of its application for a nuclear gyroscope in the angle sensor mode is given. The results of experiments confirming the effectiveness of the presented method of nuclear gyro signal refinement are presented.

A Long-term Spatial and Temporal Analysis of NDVI Changes in Java Island Using Google Earth Engine

Java is Indonesia’s and the world’s most populous island. The increase in population on the island of Java reduces the area of forest and other vegetation covers. Landslides, floods, and other natural disasters are caused by reduced vegetation cover. Furthermore, it has the potential to lead to the extinction of flora and fauna. The Normalized Difference Vegetation Index (NDVI) can be used to monitor the vegetation cover. This study analyzes the NDVI changes value from 2005 to 2020 using Terra and Aqua MODIS image data processed using Google Earth Engine. Processing was carried out in some stages: down-setting, performing NDVI processing, calculating monthly average NDVI, calculating annual average NDVI, and analyzing. From the study results, the NDVI value of Terra and Aqua MODIS data has a solid but imperfect correlation coefficient due to differences in orbital time which causes differences in solar zenith angle, sensor viewing angle, and azimuth angle. Then from this study, it was found that overall, changes in vegetation density cover on the island of Java decreased, which was indicated by the NDVI decline rate of -0.00047/year. The most significant decrease in NDVI value occurred in the period 2015–2016, covering an area of 13994.630 km2, and the most significant increase in NDVI occurred in the period 2010–2011, covering an area of 2256.101 km2.

Modeling the Influence of Engine Dynamics on Its Indicator Diagram

This article presents a proposal to describe the pressure changes in the combustion chamber of an engine as a function of the angle of rotation of the crankshaft, taking into account changes in rotational speed resulting from acceleration. The aim of the proposed model is to determine variable piston forces in simulation studies of torsional vibrations of a crankshaft with a vibration damper during the acceleration process. Its essence is the use of a Fourier series as a continuous function to describe pressure changes in one cycle of work. Such a solution is required due to the variable integration step during the simulation. It was proposed to determine the series coefficients on the basis of a Fourier transform of the averaged waveform of a discreet open indicator diagram, calculated for the registration of successive cycles. Recording of the indicative pressure waveforms and shaft angle sensor signals was carried out during tests on the chassis dynamometer. An analysis of the influence of the adopted number of series coefficients on the representation of signal energy was carried out. The model can also take into account the phenomenon of work cycle uniqueness by introducing random changes in the coefficients with magnitudes set on the basis of determined standard deviations for each coefficient of the series. An indispensable supplement to the model is a description of changes in the engine rotational speed, used as a control signal for the PID controller in the simulation of the load performed by the dynamometer. The accuracy of determining the instantaneous rotational speed was analyzed on the basis of signals from the crankshaft position angle sensor and the piston top dead center (TDC) sensor. Limitations resulting from the parameters of digital signal recording were defined.

Study on the Lower Extremity Rehabilitation Device RHleg

<p class="0abstract">This paper introduces a device to support lower extremity rehabilitation for stroke patients. First, the device's mechanical structure has been presented; the device has a simple structure and fully meets the exercise function for the patient. The equipment is controlled by control and monitoring software, which is designed from Visual Basic software. The control circuit is the Arduino 2560 circuit, responsible for receiving the angle sensor signal and measuring the current during operation. In addition, the control circuit provides control signals to the actuator and communicates with the software using the rs232 cable. Next, the mathematical model of the device has been established, and we use MatLab software to simulate the response of the device to the PID controller. Simulation results for fast response time and slight overshoot. Finally, an experiment on volunteers was conducted, the results showed that the device was stable and safe to operate. Thus, the RHleg device has been successfully designed and manufactured, tested on volunteers with good results, and this is the basis for us to continue moving towards patient testing.</p>

Modeling, Implementing and Evaluating of an Advanced Dual Axis Heliostat Drive System

Heliostat tracking is a critical component of the solar field of concentrating solar power tower (SPT) systems and can be the source of significant losses in power and profit when it lacks the necessary accuracy. This paper presents an advanced heliostat drive system for the SPT generation plant. An integrated model for the heliostat drive system based on dual axes tracking is proposed using an inexpensive angle sensor. The mathematical model of the integrated drive system is developed, including the solar, tower, and heliostat models. The MATLAB simulation model for the proposed integrated drive system is developed and evaluated. An experimental prototype for a dual-axis heliostat is built using Class-E DC choppers and an inexpensive Gyro angle sensor. The prototype is tested and considered in the Dhahran region in Saudi Arabia under different operating conditions. A comparative study between simulation and experimental results is conducted to assess the efficacy and accuracy of the proposed controller drive system and validate the developed integrated model. Both simulation and experimental results demonstrate the effectiveness of the proposed dual-axis trackers to follow the sunbeams throughout the year.