INCAS Bulletin最新文献

{"title":"Orbital dynamics and characterization of space debris via optical observations","authors":"Hager Ghoniem, M. Radwan, H. Dwidar, Y. Abdel-Aziz, Ahmed Magdy ABDEL-AZIZ","doi":"10.13111/2066-8201.2023.15.1.5","DOIUrl":"https://doi.org/10.13111/2066-8201.2023.15.1.5","url":null,"abstract":"Studying the long-term dynamical evolution of space debris and the development of optical measurements help us to avoid collision risks caused by these objects. In this work we studied the long-term evolution of space debris orbits, in GEO and MEO regions, under the effect of natural perturbations. The perturbations considered are the Earth’s gravitational field, luni-solar attraction and solar radiation pressure as well. To characterize and track the space debris we used the optical space surveillance system (OSTS) constructed by the National Research Institute of Astronomy and Geophysical (NRIAG). To better understanding the long-period dynamics we carried out several numerical explorations on space debris with small area-to-mass ratio ((between 0.009𝑚𝑚2/kg and 0.09𝑚𝑚2/kg). We found that zonal potential and solar radiation pressure play an important role in the dynamics of the problem.","PeriodicalId":37556,"journal":{"name":"INCAS Bulletin","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47127758","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Possible Evolution of Black Holes by Using a Hydrodynamic Analogy","authors":"C. Berbente, S. Berbente","doi":"10.13111/2066-8201.2023.15.1.1","DOIUrl":"https://doi.org/10.13111/2066-8201.2023.15.1.1","url":null,"abstract":"The creation of black holes starts with the implosion of a star after the fuel to power the thermonuclear reactions from inside was consumed. Then more and more mass is added until a critical value of the ratio mass/radius was obtained. This ratio contains the Schwarzschild radius, the general relativity being taken in consideration as well. Mainly, the definition of the black hole implies the impossibility of light to leave the black hole/ Essentially, the definition of a black hole implies that light cannot leave the black hole. In this paper, we show that the inability of HD-gravitons to leave a black holes will affect the black hole evolution. In this paper, we show that the inability of HD gravitons to leave a black hole will affect the evolution of the black hole.","PeriodicalId":37556,"journal":{"name":"INCAS Bulletin","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43359113","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"On Unmanned Aircraft as a Security Threat","authors":"Radoslav Ivančík, P. Nečas, Branislav Lancik","doi":"10.13111/2066-8201.2023.15.1.11","DOIUrl":"https://doi.org/10.13111/2066-8201.2023.15.1.11","url":null,"abstract":"This paper represents a continuation of the ongoing research of authors who, in the framework of interdisciplinary scientific research, deals with several aspects of ensuring the safety of the Slovak Republic and the European Union in connection with aviation, aircraft, air traffic and airspace protection. In their current research, following these and constant developments in the field of innovation and introduction of new technologies in the field of aviation, the authors deal with unmanned aircraft, which are gradually used not only in the military, but are increasingly penetrating the commercial sphere of civil aviation. Due to the fact, that the unmanned aircraft market is the fastest growing market of all categories of aviation, the authors in the article provide a theoretical and terminological view of the researched issues, including a brief historical view of the development of unmanned aircraft.","PeriodicalId":37556,"journal":{"name":"INCAS Bulletin","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47556305","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mathematical Description of the Functioning of the Pulsatory Liposome","authors":"D. Popescu, D. Iga, A. G. Popescu, Valentin I. R. Niculescu","doi":"10.13111/2066-8201.2023.15.1.7","DOIUrl":"https://doi.org/10.13111/2066-8201.2023.15.1.7","url":null,"abstract":"We consider a liposome filled with the aqueous solution of an osmotic solute enclosed in a large water bath. Due to osmotic pressure, it works according to a sequence of cycles with two stages. In the first stage, the lipid vesicle with a certain input concentration of the osmotic substance is swelling up in an osmotic process until it reaches a size, when one pore is formed on its surface. The second stage follows, where the vesicle content is partially eliminated through the pore to induce a decrease in the vesicle volume up to its original size. If we take into account that the pore has two stages in its evolution, then the relaxing stage may be divided into two new stages. The swelling of the liposome is described by a differential equation. All the processes which contribute to the vesicle relaxing and its return to the initial size are described by three differential equations.","PeriodicalId":37556,"journal":{"name":"INCAS Bulletin","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47143976","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Multi-response optimization of process parameters during friction stir welding of AA2014-AA7075 using TOPSIS Approach","authors":"P. Umamaheswarrao","doi":"10.13111/2066-8201.2023.15.1.10","DOIUrl":"https://doi.org/10.13111/2066-8201.2023.15.1.10","url":null,"abstract":"In this study, multi-objective optimization for Friction stir welding of dissimilar AA2014-AA7075 has been presented to provide optimum tensile strength, hardness, and % of elongation. The input parameters considered for the analysis are tool rotational speed, feed, and tilt angle. Experiments are designed based on Taguchi L9 orthogonal array. Investigative analysis on the effect of input parameters on the responses is carried out using the MINITAB14 software package. The parametric influence on responses is discussed through the main effects plot. Further, multi-objective optimization is performed with the Technique for order of preference by similarity to ideal solution (TOPSIS). Results demonstrated that tool rotational speed is the most significant factor affecting the response followed by feed and tilt angle. The optimum cutting parameters obtained are tool rotational speed 710 rpm, Feed 30 mm/rev, and Tilt angle 2o.","PeriodicalId":37556,"journal":{"name":"INCAS Bulletin","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45669332","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Thermo-mechanical properties of fused filament fabricated PLA at elevated temperatures","authors":"G. Pelin, Cristina-Elisabeta Pelin, Mihail Botan, A. Stefan, G. Cristea, Alexandra Ana Maria Panait","doi":"10.13111/2066-8201.2023.15.1.6","DOIUrl":"https://doi.org/10.13111/2066-8201.2023.15.1.6","url":null,"abstract":"This study aims to present the authors' recent research investigating the mechanical and thermo-mechanical properties of commercial polylactic acid (PLA) polymer. Samples were manufactured by 3D printing of fused filament fabrication (FFF) and tests were performed according to ASTM International standards for polymers D638, D695 and D790. All test samples were made using the same printing process parameters. The static mechanical tests consisted of tensile and flexural loadings at various temperature ranges, from room temperature to elevated temperature (25°C, 40°C and 50°C, respectively). For ensuring that the additively manufactured products can resist severities of real-life applications, thermal stability under mechanical load tests (HDT - heat deflection temperature) were carried out. The temperature influence on the mechanical and thermomechanical properties was determined and presented, and a synthesis of the characteristics was made in accordance with the applications of products based on the studied material.","PeriodicalId":37556,"journal":{"name":"INCAS Bulletin","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47400903","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A computational tool for conceptual design and optimization of planetary rovers","authors":"A. Seeni, B. Schäfer","doi":"10.13111/2066-8201.2023.15.1.8","DOIUrl":"https://doi.org/10.13111/2066-8201.2023.15.1.8","url":null,"abstract":"The design process of a Mars rover is driven by multiple design constraints, namely overall mass, power consumption and volume (dimensions). Various systems, such as mobility, manipulation, handling, power, thermal, communication, navigation, avionics and science instruments, together make a complete rover vehicle and they should function collectively to perform a given task. Each of the subsystems can be thought of as modular building blocks that are integrated together to form a fully functional rover vehicle. When approaching the design of such a vehicle, the designer should take into account of cross design dependencies existent between different subsystems and technology limitations. Performing any particular task, would lead to many design possibilities. Choosing the final design from many feasible solutions is arguably a daunting task. In order to make this process simple and convenient, as well as to understand the design non-linearity existing in this solution space, the authors have employed a systems engineering approach to develop a tool comprising subsystem models. The subsystem models comprise parametric and physics-based models. For designing suitable user-defined objectives, these models when integrated with Genetic Algorithm forms an effective tool to support design trade-offs during the conceptual design process. This integrated modeling and optimization approach is thought to be efficient in identifying rover system concepts.","PeriodicalId":37556,"journal":{"name":"INCAS Bulletin","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42250001","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Physical vs. Mathematical Problem of Navier-Stokes Equations (NSE)","authors":"H. Dumitrescu, V. Cardoş, Radu Bogateanu","doi":"10.13111/2066-8201.2023.15.1.3","DOIUrl":"https://doi.org/10.13111/2066-8201.2023.15.1.3","url":null,"abstract":"The Navier-Stokes equations describing the motion of viscous/real fluids in Rn (n = 2 or 3) depend on a positive coefficient (the viscosity, ν) via the Reynolds number. The key of NSE problem is the Reynolds number, mathematically considered a simple small perturbation parameter without any physical explanation, or a vague physical Newtonian ratio of inertial to viscous forces, 𝑅𝑅𝑅𝑅=𝑈𝑈𝑈𝑈𝜈𝜈, in spite of its quantic physical meaning as the initial excitation to response ratio, at the beginning of motion (IC at t = 0). The paper deals with the thixotropic property of real viscosity which softens (ν ↓) when strained (Re↑), but it doesn’t tend to zero (ν → 0) as much as the Reynolds number increases, holding a finite value, corresponding to the new thermodynamic equilibrium state. The (ν → 0 for Re → ∞) false physical condition renders the NSE problem to a unique solution less one beyond a critical Reynolds number, Recr. The understanding of the wall-bounded viscous flows, at both small-scales (slow motion, small Re) and larger scale (turbulent motion, large Re) must be in conjunction with the more-subtle torsional buckling effect of the “wall” lag concept that the wall has on the inherent fluid dynamics during the starting phase. The limitations of the diathermal wall associated with the starting accelerations at the onset of motion, of the order of acr/g ≥ 2/3, create the physical conditions (thermomolecular changes) for the loss of the mathematical uniqueness of the NSE solutions. The physical limitations in conjunction with the validity area of NSE model are considered in the sequel. Because of the nonlinearity of the PDE differential equations, the variation of geometrical and physical properties can lead to bifurcations in the solution and thus, to multiple solutions. Considerations relative to laminar-turbulent transition as the main bifurcation source for the more complex structure of a solution, engendered by molecular structure changes of a flowing fluid in more or less contact with the walls, are given and illustrated for the canonical flows on flat plates and viscous decay of a starting/contact vortex (“vortex eye”).","PeriodicalId":37556,"journal":{"name":"INCAS Bulletin","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42954919","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"More direct methods to evaluate general relativity effects. The influence of the age of the Universe","authors":"C. Berbente, S. Berbente","doi":"10.13111/2066-8201.2022.14.4.3","DOIUrl":"https://doi.org/10.13111/2066-8201.2022.14.4.3","url":null,"abstract":"More direct methods are given to evaluate the general relativity effects by simplifying the solving the solution of the extremum of variational problem to one variable only.\u0000The influence of the age of the Universe is mainly related to the variation of the coefficient of gravity the age of the Universe.","PeriodicalId":37556,"journal":{"name":"INCAS Bulletin","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45570916","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Analytical and Experimental study on FVA of Isotropic and Orthotropic Laminates with FEM Validations","authors":"K. Srividya, P. Anusha, E. Kavitha, M. Naga Swapna Sri, V. Sravani","doi":"10.13111/2066-8201.2022.14.4.12","DOIUrl":"https://doi.org/10.13111/2066-8201.2022.14.4.12","url":null,"abstract":"Several approaches such as two-dimensional shear deformation and higher order theories, three-dimensional exact elasticity method and 2-D, 3-D finite element procedures are available in predicting the natural frequencies of composite laminates. In all, a 3-D FEM assists in developing a model for structures with complex constraints, materials and complex geometries. But FE directs an approach that obtains an approximation in solution that depends on discretization type and the polynomials method desirable for field variable limitations. Hence, a convergence test is performed in addition to FE in order to improvise the finite element results accuracy and validating with other benchmark outcomes. The current investigation involves the solving for several boundary conditions of a thick rectangular plate’s free vibration analysis [FVA] for isotropic and orthotropic materials by the application of 3-D finite element methods and convergence results are compared with available analytical results. In addition, experiments are conducted on thick isotropic and orthotropic materials along with experimental modal analysis in order to verify 3-Dimensional finite element process. From this study it can be known that, the values of finite element method highly converges with various experimental and analytical results of isotropic material. When comparing 3-D FEM with the experimental results of the orthotropic sample, a deviation of 5-8% was observed.","PeriodicalId":37556,"journal":{"name":"INCAS Bulletin","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46318648","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}