Human reliability increasing approach in aircraft maintenance technician’s training process

This article presents an approach for increasing the maintenance technician’s reliability by considering the human fault rate as utility function’s maximization problem in the technician’s training process. Adequately trained technicians are capable to perform a maintenance and manage the reliability of their assigned assets within the complex aircraft systems. In general, a degradation of aircraft reliability, due to maintenance tecnician’s competency, typically leads to significant, undesirable safety and economic consequences. In this article, an optimal control theory is applied on the purpose of finding of a fault rate reduction series in the training process which leads to highest technician’s reliability in the maintenance process of the complex aircraft systems.

Advances in space science and technology in connection with 60−th anniversary of first human spaceflight

On April 12, 1961, Yuri Gagarin proclaimed the arrival of a new space age. The rapid advances in the different space sciences and technologies began after the first human spaceflight. Then fundamentally new sciences and technologies appeared. At present, space science covers a broad range of disciplines. The following outline is provided as an overview and topical guide to space sciences: Astronomy and Space Astronomy, Cosmology, Astrophysics, Space Physics, Solar-Terrestrial Physics, Aeronomy, Solar physics, Heliospheric Physics, Cosmic Ray Physics, Space Weather and Space Climate (Earth-Space Climatology), Space Dosimetry, Space Chemistry or Cosmochemistry, Remote Sensing of the Earth and Planets, Planetary Science, Planetary Geology, Astrogeology or Exogeology, Exoplanetology or Exoplanetary Science (Science for Extrasolar Planetary Systems), Intelligent Life in the Universe, Astronautics (or Cosmonautics), Orbital mechanics or Astrodynamics, Space life sciences: Bioastronautics, Space Medicine, Space Neuroscience, Space Biology, Radiation Biology, Biotechnology, Space Botany or Astrobotany, Microgravity Environment Research; Archaeoastronomy, Space Anthropology, Xeno-anthropology (Exo-anthropology), Space Law, Space Technology, Space Navigation, Space Communications, Space Architecture, Space Logistics, Space Robotics, Space Robotic Colonies, Space Colonization (also called Space Settlement or Extraterrestrial Colonization), Planetary Habitability, Space Manufacturing, Space Materials Science, Satellite Industry, Space Business, Space Tourism, Space Hardware, Space Industry, and Space Ecology. With the help of these advanced space sciences humankind began confidently the exploration of space. But these studies led also to numerous new technologies and applications to improve people's lives. Finally, we mention again Yuri Gagarin and his cosmic heritage. He left behind an inspirational legacy, which even today still continues to motivate millions of people worldwide.

Analysis of the military application of unmanned aircraft and main direction for their development

Modern military unmanned aerial vehicles (UAVs) are assigned a wide range of functions, for the implementation of which they perform many tasks in various military conflicts. The results of the analysis give them the opportunity to reveal the problems in the use of UAVs, make changes in their functions and tasks and identify areas for further development. At present, this requires the introduction of the achievements of artificial intelligence, the introduction of expert systems and microelectronics on board UAVs, as well as their integration with various other means of conducting armed struggle. At the same time, some of the technological solutions for the creation and improvement of UAVs for military purposes can be applied in the civilian sector.

Seasonal changes of Sahara desert dust transport over Balkans

This article presents an investigation of seasonal behavior of Sahara desert dust transport over the Balkans. The data used is satellite measurements of monthly averaged Absorption Aerosol Index (AAI) value. The researched period is from June 1995 till the end of 2019. The data used is from four different space instruments onboard five satellites. The area of interest is a rectangle with corners 23 E 43 N and 24 E 35 N. The data from different sources is compared and discussed.

Aerodynamic performance of chevron geometry trailing edge for a transonic axial compressor impeller

Several studies present how serrated rotor blades mix wakes in order to attenuate noise levels. The current paper analyses how this geometry, applied on the trailing edge, affects the global parameters of a transonic axial compressor impeller. Innovative solutions tackling the rotor-stator interaction mechanism in an axial compressor for noise reduction include serrated trailing edges. Inspired by chevron nozzles, serrations can be transferred to the open-rotor concept in order to reduce tonal noise. Throughout the study we will be focusing on aerodynamic loss estimation while being mindful of the mechanisms which lead to rotor-stator interaction noise, without assessing its per-se effectiveness for noise mitigation. Owing to its qualitative experimental data availability, NASA’s Rotor 37 was chosen as a baseline. A set of fully viscous 3D simulations, using the SST k omega turbulence model and RANS, was carried out to this effect. Spatial discretization was made using a fully structured pre-mesh in order to optimize resolution and accelerate convergence. Full-factorial samples were generated for the geometric variations in order to capture the aerodynamic implications of this concept. Overall, the analysed case provides promising perspectives, pending optimization studies and experimental tests thereof.

Applying the constant strength doublet method to resolve a steady flow around an airfoil

In the paper hereby, a numerical (panel) method is applied to analyze steady two-dimensional flow of ideal gas around an airfoil. Initially, the airfoil is divided into a finite number of panels. Then the panels are replaced by doublets with constant strength. In addition, a wake panel is added to fulfill Kutta condition at the airfoil trailing edge. In order to implement this, a numerical realization is developed and built by means of Tiny C Compiler. To work out a solution to the linear non-homogeneous algebraic system, direct schemes for lower-upper factorization/decomposition of matrix of coefficients were applied, namely Crout, Doolittle, and Cholesky. The obtained results are validated against exact solution and shown for various values of angle of attack and Reynolds number.

Application of GNSS and SAR data in landslide monitoring along the Black Sea coast of Bulgaria

Landslide processes are considered to be the major part of the natural hazards occurring on the northern part of the Bulgarian sea side. Their monitoring can be done with high precision using GNSS data. The objective of this study is to provide solid grounds for monitoring of the landslide processes using GNSS and SAR data. This goal will be achieved by implementation the following: 1) establishment a verified methodology for extracting high-quality information from SAR images aimed at continuous monitoring of landslide areas integrating InterFerometric Images (IFI) and GNSS data and 2) creation of working prototype of an information system for monitoring and prevention of the effects of earth crust movements (landslides, falls, etc.) based of freely accessible data provided by ESA and national sources. One of the scientific tasks to be solved includes the development of methodological approaches for comparison of the results from combined processing of interferometric images from SAR, measurements at permanent GNSS stations of the national NIGGG network in the area of study and geodetic measurements of a newly established test network covering a specific area on the Northern Black Sea coast of Bulgaria with active landslide processes.

Usage of eye tracker technology in examining attention distribution of operators of unmanned aerial vehicles

This article proposes yet another approach towards looking into causes for attention distribution of an operator of unmanned aerial vehicle. During examination, the operator is being tested at dedicated flight simulator while data are gathered and visualized through a mobile eye tracker. Two work stages are considered sequentially, i.e. building a geometric 2D transformation of region of interest (homography) within an image, and overlaying a dynamic heatmap as well. In the former stage, spontaneous movements of the operator’s head, recorded by the video, are eliminated thus enabling the operator to use the mobile eye tracker instead of a desktop-based one. During the latter stage, the distribution of operator’s attention over time is displayed. In order to implement the current research, a source code has been developed in C++ for some features readily available in OpenCV library to be used. In addition, data gathered after carrying out flight session are processed and discussed thoroughly.

Interferometric processing of TanDEM-X bistatic SAR data using GAMMA – implementation outline

This article represents a showcase of two different coding approaches with GAMMA, used to calculate topographic and differential phases from high resolution TanDEM-X bistatic data, provided by DLR. The first implementation approach comprises “BASH” scripting in Linux environment, having direct control of the GAMMA executables. The second approach is utilization of the PyroSAR framework, via GAMMA-API, in Python environment. Two spatial resolution scales are used – of 4 and 12 meters, to test feasibility of TanDEM-X InSAR output products in mountainous forest in rugged region. The first approach allowed thorough processing with abundant GAMMA output, whereas the high scale PyroSAR framework via GAMMA-API showed fast implementation. Comparison over 4 and 12m spatial resolution products showed good feasibility with strong influence from topography. Intense multi-looking resolved better connection of coherence amplitude to the volume decorrelation in canopy, despite preserving high resolution reveals plenty of details in land cover. Differential height calculation, without phase unwrapping, showed its significance in data processing over mountainous regions. Intensities normalization and terrain flattening showed good performance in both resolution scales. Finally, utilization of GAMMA in InSAR processing of high resolution TanDEM-X bistatic SAR data showed good feasibility and flexibility to derive interferometric products.

Description of the "Liulin Ten-Koh" charged particles spectrometer for the Japanese "Ten-Koh" satellite

On 29 October 2018 at 13:08 Japanese Standard Time was successfully launched the Greenhouse gas Observing SATellite (GOSAT-2) from the JAXA Tanegashima Space Center. Piggy-back with the GOSAT-2 satellite in a circular (623 km), polar synchronous orbit, was launched the 22 kilogram mass satellite Ten-Koh (http://kit-okuyama-lab.com/en/ten-koh/). It was developed in Kyushu Institute of Technology by Prof. K. Okuyama, Chief Scientist of the Spacecraft. Ten-Koh satellite is observing Low Earth Environment (LEO). The primary purpose is to provide valuable data for future development of satellites for operation. Ten-Koh's primary science instrument is the Charged Particle Detector (CPD) developed at the Prairie View A&M University, and NASA Johnson's Space Center of Houston, TX, USA. Principal Scientist of this payload is Prof. P. Saganti (https://www.pvamu.edu/raise/space-payload/charged-particle-detector-2018/). Principal Engineer of the CPD project is S. D. Holland (formerly with NASA-JSC and currently with Holland-Space LLC, Houston, TX, USA). SRTI-BAS received a request from Prof. Saganti to develop a Liulin type instrument to be part of the CPD payload. Scientists from SRTI's Solar-Terrestrial Physics Department have developed and handed three units per the request (engineering, flight, and operational models) of the instrument named ?Liulin Ten-Koh?. These instruments are similar to the RADOM instrument, which worked in 2008-2009 on the Indian Moon satellite Chadrayaan-1 [12]. This paper describes the flight model, ?Liulin Ten-Koh Saganti? instrument and the standard sources radiation tests, which were performed during the calibrations in the laboratory of SRTI-BAS. As of this writing, Ten-Koh spacecraft is making polar orbit passes as expected at about 623 km altitude and at 98 degree inclination with very healthy telemetry data as received by several ground stations across the world. The first received data from ?Liulin Ten-Koh Saganti? instrument of the Ten-Koh spacecraft are presented. The available at this moment Galactic Cosmic Rays (GCR) L-value profiles of the dose rate and the dose to flux ratio (D/F) from 11 December 2018 are compared with the R3DE profile at International Space Station (ISS). In addition, the integral ?Liulin Ten-Koh Saganti? instrument LET spectrum from 11 December 2018 is compared with spectra from other instruments, measured in and out of the Earth magnetosphere.