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Abstract

Carbon-epoxy composite materials, due to their high strength in relation to mass, are increasingly used in the construction of aircraft structures, however, they are susceptible to a number of damages. One of the most common is delamination, which is a serious problem in the context of safe operation of such structures. As part of the TEBUK project, the Institute of Aviation has developed a methodology for forecasting the propagation of delamination. In order to validate the proposed method, an aerial structure demonstrator, modelled on the horizontal stabilizer of the I-23 Manager aircraft, was carried out. However, in order to carry out the validation, it was necessary to "simplify" the demonstrator model. The paper presents a numerical analysis conducted in order to separate from the TEBUK demonstrator model a fragment of the structure, which was used to study the delamination area, as an equivalent of the whole demonstrator. Subcomponent selection was carried out in several stages, narrowing down the analysed area covering delamination in subsequent steps and verifying the compliance of specific parameters with the same parameters obtained in a full demonstrator model. The parameters compared were: energy release rate values on the delamination front line and strain values in the delamination area. The numerical analyses presented in the paper were performed with the use of the MSC.Marc/Mentat calculation package. As a result of the analyses, a fragment of the structure was selected, which allows to significantly reduce the time and labour consumption of the production of the studied object, as well as to facilitate experimental research.

Abstract

The main objectives of this work are to optimize the extraction parameters, to test the antioxidant activity of Aloe Vera extract and to study the impact of this extract on deteriorating molds of Algerian variety of wheat (CIRTA). The extraction was optimized by central composite design. Determination of the polyphenols, flavonoids, and proanthocyanidins was performed by using colorimetric assays. Identification and quantification of phenolic compounds were performed by RPHPLC-UV method. The antioxidant activity was tested by three methods: 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,20-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS), and CUPRAC (Cupric reducing antioxidant capacity), the antifungal activity of Aloe Vera extract on isolated strains from durum wheat were tested by dilution in a solid medium method. The optimum of total phenolic got was1,044 x 104 µg GAE/g of dry extract. The extract is rich in polyphenols, flavonoids, and proanthocyanidins. The analysis of phenolic compounds of Aloe Vera by RP-HPLC-UV revealed seven phenolic compounds. Strong antioxidant activity was obtained for Aloe Vera extract. Purification and microscopic study of isolated strains gave the possibility of identifying four strains: Alternaria spp1, Alternaria spp2, Penicillium spp, and Aspergillus spp. the antifungal potential of Aloe Veravaries according to the fungal genera and the concentrations of extract used.

Abstract

The focus of this paper was to assess the phytochemical composition, the antioxidant and antibacterial activities of the crude extracts of the aerial parts of Ferula lutea. Four new compounds were isolated from this genus, and their structures were primarily established by extensive spectroscopic analysis including 1D and 2D spectroscopic techniques. Total phenolics and flavonoids containing in ethyl acetate (AcOEt) and n-butanol (n-BuOH) extracts were quantified [199.1-184.02 mg gallic acid equivalent / g of dry weight], flavonoids [70.24-65.95 mg quercetin / g dry weight]. DDPH scavenging and phosphomolybdenum methods were used to evaluate in vitro antioxidant activity. The obtained results showed a significant antioxidant activity of the two aerial parts. Correlation analysis between the DPPH values and those for TAC indicates the possibility of the two models for evaluating antioxidants power from medicinal plants. Dichloromethane (CH2Cl2), AcOEt and n-BuOH extracts were screened against two gram-negative [Escherichia coli (E.coli) and Pseudo aeruginosa (P.aer)] and two gram-positive [Staphylococcus aureus (S.aur) and Bacillus (Bacil.)] bacteria using disc diffusion method. The results indicate a good inhibition of CH2Cl2 and EtAct extracts on the growth of (Bacil. and E.coli). Furthermore n-but extract showed a significant inhibitory effect only against E.coli.

Abstract

Stratospheric balloons are very important sources for space and terrestrial observation experiments in many disciplines. Instruments developed for astrophysical measurements are usually reusable. It is also possible to observe both hemispheres including observations from the polar and equatorial regions for thirty days or even longer. On the other hand the UV atmospheric transmittance window was used for the astrophysical observations less often than visible optical bands. At the end of the 2017 there are a few scientific groups working on near-UV or UV spectrographs and cameras for balloon flights.

In this paper we are discussing the possibility of ultraviolet measurement of Enceladus, an icy Saturnian moon, surface reflectance between 200 and 400 nm from the 20-50 km altitudes. At visible and near infrared optical channels Enceladus’ reflectance is very high (near 1.0). This value is consistent with a surface composed of water ice, however at some ultraviolet wavelengths Enceladus reflectance is lower than it would be expected for this type of surface. The scientific research done in the last decade was focused on H2O, NH3, and tholin particles detection on the Enceladus’ surface as a reason of low UV reflectance phenomenon. Continuous observation of Enceladus’ UV reflectance variability from stratospheric balloons may be interesting and may give us the proof of the presence of biomarkers or/and tholin particles.

Abstract

European Commision adopted in July new regulations about laying down airspace usage requirements and operating procedures concerning performance based navigation. It is next step in realization of the the global program PBN ICAO. At the 36th General Assembly of ICAO held in 2007, the Republic of Poland agreed to ICAO resolution A36-23 which urges all States to implement PBN. In future aviation concepts the use of Performance Based Navigation (PBN) is considered to be a major Air Traffic Management (ATM) concept element. ICAO has drafted standards and implementation guidance for PBN in the ICAO Doc 9613 “PBN Manual”. The Based Performance Navigation Concept represents and shift from sensor-based to performance based navigation connected with criteria for navigation: accuracy, integrity, availability, continuity and functionality depending on the phase of the flight. Through PBN and changes in the communication, surveillance and ATM domain, many advanced navigation applications are possible to improve airspace efficiency, improve airport sustainability, reduce the environmental impact of air transport in terms of noise and emission, increase safety and improve flight efficiency.

Abstract

In this study we evaluated new mixing (θ and ψ) Pitzer parameters, and developed models for solution behavior and solid liquid equilibria for the following mixed systems: 1) KCl-AlCl3-H2O, 2) KCl-FeCl3-H2O, 3) KCl-CrCl3-H2O, 4) MgCl2-AlCl3-H2O, 5) MgCl2-FeCl3-H2O, 6) MgCl2-CrCl3-H2O, 7) CaCl2-AlCl3-H2O, 8) CaCl2-FeCl3-H2O, and 9) CaCl2-CrCl3-H2O at 25°C. The solubility modeling approach, implemented to the Pitzer specific interaction equations is employed. The values of the binary parameters for the binary sub-systems needed here to parameterize models for mixed systems are taken from our previous studies. Mixing solution parameters are evaluated in this study using activity (when available) and solubility data. Following an approach in our previous modeling studies on M(III) chloride and sulfate systems, in this work we accept that complex Al(III), Cr(III), and Fe(III) aqueous species do not exist in solutions. We test the new models by comparing model predictions with experimental data (activity data for unsaturated solutions and solubility data in ternary systems). The agreement between model predictions and experimental data is very good. Combining present parameterization, with our M(III) models developed previously we fully complete our at 25°C model for the 8th component system Na-K-Mg-Ca-Al(III)-Cr(III)-Fe(III)-Cl-H2O. The resulting model calculates solubilities and solution activities to high solution concentration within experimental uncertainty. Limitations of the model due to data insufficiencies are discussed. The resulting parameterization was developed for the Pitzer formalism based PHREEQC database.

Abstract

Based on the response of small-scale model square footing, the present paper shows the results of an experimental bearing capacity of eccentrically loaded square footing, near a slope sand bed. To reach this aim, a steel model square footing of (150 mm × 150 mm) and a varied sand relative density of 30%, 50% and 70% are used. The bearing capacity-settlement relationship of footing located at the edge of a slope and the effect of various parameters such as eccentricity (e) and dimensions report (b/B) were studied. Test results indicate that ultimate bearing capacity decreases with increasing load eccentricity to the core boundary of footing and that as far as the footing is distant from the crest, the bearing capacity increases. Furthermore, the results also prove that there is a clear proportional relation between relative densities –bearing capacity. The model test provides qualitative information on parameters influencing the bearing capacity of square footing. These tests can be used to check the bearing capacity estimated by the conventional methods.

Abstract

The paper evaluates the effectiveness of reinforcing a damaged earth structure with making counterfort drains in its slope. The system of counterfort drains changed the soil properties significantly over a long-term use. The evaluation was based on many years of field and laboratory tests and stability analysis. The field tests concerned the observation of N WST probing resistance change, and the laboratory tests concerned the change in soil consistency and water content. The paper presents the results of tests that were conducted over 13 years.

Abstract

In this work, the input-output method of dynamic parameters' identification is experimentally tested. A method based on the transformation of a dynamic problem into a static problem by means of integration of the input and output signal was presented. The problem discussed in this article is the identification of the coefficients of stiffness matrices and eigenfrequencies of a discrete dynamic system subjected to kinematic input. The experimental analysis was carried out on a three-storey slab-and-column structure, which constitutes a physical model of a building. The vibrations of the model were excited kinematically by an earthquake simulator. The device has a computer-controlled, movable table top, which can move independently in three directions, that is, horizontally, vertically, and rotationally around the vertical axis.

The aim of the experimental studies presented in this work was to determine the dynamic parameters of the model (stiffness, natural frequencies) using the input-output method in the time domain. Moreover, the results obtained with this method were compared with the results of experimental modal analysis (EMA) in order to verify their correctness. It was assumed that the movement of the base is horizontal and occurs in one direction. Two short-term, irregular kinematic excitations of the construction were considered, and the selected results and conclusions from experimental analyses were presented in this work.

Abstract

In the present manuscript, unsteady magnetohydrodynamic (MHD) flow over a moving porous semi-infinite vertical plate with time-dependent suction has been studied in the presence of chemical reaction and radiation parameters. Time-dependent partial differential equations in the dimensionless form are solved numerically through mathematical modelling in COMSOL Multiphysics. The results are obtained for velocity, temperature and concentration profiles at different times. Steady state results are also presented for different values of physical parameters. The parameters involved in the problem are useful to change the characteristics of velocity, heat transfer and concentration profiles. The numerical solution of partial differential equations involved in the problem is obtained without sacrificing the relevant physical phenomena.