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Abstract

The paper presents research on the near real-time atmospheric sounding system. The main objective of the research was the development and testing of the weather sounding system based on a weather balloon. The system contains a redundant system of radiosondes, a lifting platform containing weather balloon and a holding system as well as ground station. Several tests of the system were performed in August and September 2019. Altitude, reliability, resistance to weather conditions and data convergence were tested. During tests, new procedures for such missions were developed. The final test was performed for the ILR-33 Amber Rocket as a part of pre-launch procedures. The test was successful and allowed to use acquired atmospheric data for further processing. Several post-tests conclusions were drawn. The altitude of sounding by a weather balloon depends mostly on weather conditions, the amount of gas pumped and the weight of a payload. The launching place and experience of the crew play an important role in the final success of the mission, as well.

Abstract

The presented paper considers a comparison of the traditional methods for the state maximal probability determination to the proposed hybrid probabilistic and variational concept. It is shown the advantages of the described multi-optional hybrid-effectiveness functions uncertainty measure conditional optimization doctrine in the sense of avoiding the traditional ways analytical complicatedness concerning the maximal probability of the possible state determination. The results of the numerical example are presented.

Abstract

The article is in line with the contemporary interests of companies from the aviation industry. It describes thermoplastic material and inspection techniques used in leading aviation companies. The subject matter of non-destructive testing currently used in aircraft inspections of composite structures is approximated and each of the methods used is briefly described. The characteristics of carbon preimpregnates in thermoplastic matrix are also presented, as well as types of thermoplastic materials and examples of their application in surface ship construction. The advantages, disadvantages and limitations for these materials are listed. The focus was put on the explanation of the ultrasonic method, which is the most commonly used method during the inspection of composite structures at the production and exploitation stage. Describing the ultrasonic method, the focus was put on echo pulse technique and the use of modern Phased Array heads. Incompatibilities most frequently occurring and detected in composite materials with thermosetting and thermoplastic matrix were listed and described. A thermoplastic flat composite panel made of carbon pre-impregnate in a high-temperature matrix (over 300°C), which was the subject of the study, was described. The results of non-destructive testing (ultrasonic method) of thermoplastic panel were presented and conclusions were drawn.

Abstract

Noise generated by helicopters is one of the main problems associated with the operation of rotorcrafts. Requirements for reduction of helicopter noise were reflected in the regulations introducing lower limits of acceptable rotorcraft noise. A significant source of noise generated by helicopters are the main rotor and tail rotor blades. Radical noise reduction can be obtained by slowing down the blade tips speed of main and tail rotors. Reducing the rotational speed of the blades may decrease rotor thrust and diminish helicopter performance. The problem can be solved by attaching more blades to main rotor. The paper presents results of calculation regarding improvement of the helicopter performance which can be achieved for reduced rotor speed but with increased number of rotor blades. The calculations were performed for data of hypothetical light helicopter. Results of simulation include rotor loads and blade deformations in chosen flight conditions. Equations of motion of flexible rotor blades were solved using the Galerkin method which takes into account selected eigen modes of the blades. The simulation analyzes can help to determine the performance and loads of a quiet helicopter with reduced rotor speed within the operational envelope of helicopter flight states.

Abstract

One of important problems in aerospace engineering is to determine the amount of fluid in the tank in a microgravity environment. There are several methods for doing it, however, there are no proven methods to quickly gauge the amount of propellant in a tank in low gravity conditions. New and more accurate methods of such a measurement are being continually searched for. One of interesting solutions is using Electrical Capacitance Tomography (ECT) for this purpose. The article presents both numerical analysis and experimental test results using a spherical tank. The main purpose of the simulation was to determine the effect of the number of electrodes and noise signal level on the quality of reconstruction images. In numerical simulations, different models of dielectric permittivity distribution have been reconstructed. On the basis of numerical simulations, a 24-electrode sensor was designed and made. In experimental tests, different distribution of medium inside the spherical tank was investigated. The results show that the method can directly measure the mass of fuel in the tank, as well as it allows for a visualization of fuel distribution, independent of the tank position in space, and the liquid-propellant system will be used.

Abstract

The present study deals with the estimation of the evolution tendency of the environmental stage of a protected habitat with predominant forest vegetation, during a short period of time, using techniques specific to remote sensing. Therefore, two important spectral indexes were tested while assessing the health of the forest ecosystems: i.e. the Normalized Difference Vegetation Index (NDVI) and the Structure Insensitive Pigment Index (SIPI). The period of time taken into consideration for the study was, 2013 - 2019, having used medium resolution satellite photos, Landsat 8 OLI, having initially undergone standard pre-processing operations (resize data, radiometric calibration, atmospheric correction). The satellite images modified according to the Top of Atmosphere Reflectance and corrected topographically resulted into getting values for the two before mentioned indexes. The quantity-spatial results obtained, correlated to the monthly values of the precipitations processed in order to obtain the SPI (Standardized Precipitation Index), mostly reveal, in what SIPI and also NDVI are concerned, a slight decrease in the quality of the forest on the analysed area in the sense that the vegetation stress is increased under meteorological factors, expressed differently depending on the morphometric and pedological parameters of the habitat.

Abstract

Productivity is a significant aspect of construction industry that plays vital role for success and failure of any construction project. This industry generates 11% to 13% of GDP all around the globe and the cost of labour in any building project is 20% to 35% of the cost of Building. On daily basis labour utilizes 30% of time on productive activities rest 70% of the time is ruined in non-productive activities, there are multi factors which are affecting the labour production in construction industry hence this study provides an overview of productivity, Total Factor productivity, method used to measure accurate productivity in construction projects. The objective of this study is find out percentage up to what extent labour production is affected due to weather conditions, however this study is carried out in arid climate region in Month of June 2018, where minimum temperature was recorded 26.0 Celsius degree at 7:30 AM and Maximum was 47.80 Celsius degree at 3:00 PM. A descriptive survey research design approach was adopted using continuous observation method of study. Project work study manual served as the research instrument to collect the data on selected building sites for 30 working days. Data collected were analyzed using descriptive statics. The results show that average monthly production of mason gang was recorded with less production of 28.759%, Carpentry gang with average monthly loss of production 16.74% & steel fixer gang had average monthly loss of production was 12.188. This concludes that prior to signing the contract for construction project. The location, environment, topography of region, capacity of construction operatives must be kept in mind to decide the proper timeline for the successful of project.

Abstract

Autonomous underwater gliders are buoyancy propelled vehicles. Their way of propulsion relies upon changing their buoyancy with internal pumping systems enabling them up and down motions, and their forward gliding motions are generated by hydrodynamic lift forces exerted on a pair of wings attached to a glider hull. In this study lift and drag characteristics of a glider were performed using Computational Fluid Dynamics (CFD) approach and results were compared with the literature. Flow behavior, lift and drag forces distribution at different angles of attack were studied for Reynolds numbers varying around 105 for NACA0012 wing configurations. The variable of the glider was the angle of attack, the velocity was constant. Flow velocity was 0.5 m/s and angle of the body varying from −8° to 8° in steps of 2°. Results from the CFD constituted the basis for the calculation the equations of motions of glider in the vertical plane. Therefore, vehicle motion simulation was achieved through numeric integration of the equations of motion. The equations of motions will be solved in the MatLab software. This work will contribute to dynamic modelling and three-dimensional motion simulation of a torpedo shaped underwater glider.

Abstract

The article presents research conducted with the project: ‘Additive manufacturing in conduction with optical methods used for optimization of 3D models’’ [2]. The article begins with the description of properties of the materials used in three different additive technologies – Fused Deposition Modelling (FDM), Selective Laser Sintering (SLS) and Material Jetting (MJ). The next part focuses on the comparative analysis of macro- and microstructure of specimens printed in order to test selected materials in additive technologies mentioned above. In this research two types of specimens were used: dumbbell specimens and rectangular prism with hole specimens. In order to observe macrostructure specimens, they were subjected to load test until it broke. In the case of observing microstructure, they were cut in some places. Each of described additive technologies characterizes by both different way of printing and used materials. These variables have a significant influence on macro- and microstructure and fracture appearance. FDM technology specimens printed of ABS material characterized by texture surface appearance. SLS technology specimens printed of PA12 material characterized by amorphous structure. MJ technology specimens printed of VeroWhite Plus material characterized by fracture appearance which had quasi- fatigue features. The microstructure of these specimens was uniform with visible inclusions.

Abstract

The article presents the description of technological trials and the results of three methods of machining carbon fiber reinforced composites panels. It also reviews the literature concerned heat affected zone in composites and its influence on material properties. As a part of the research, the cutting method using diamond coated saw was tested, as well as the milling method with two different types of carbide milling cutters. The processing of the panels was done using 4-axis CNC machine with special adapter for cutting discs in Composite Testing Laboratory (Center for Composite Technologies, Warsaw Institute of Aviation). The methods were compared in terms of machined edge quality and panel temperature during the processes. For this purpose, thermocouples were mounted into panels. Records from thermocouples were included. Edge quality and surface roughness have been checked by microscopic observation. Additionally, samples machined by each evaluated processing method were tested using differential scanning calorimetry (DSC). The method was used to determine the glass transition temperature of the tested material. The article conclusions contain a comparison of three processing methods in terms of cutting quality, process temperature, processing method productivity as well as DSC tests results.