Laguerre-like methods for the simultaneous approximation of polynomial multiple zeros

Two new methods of the fourth order for the simultaneous determination of multiple zeros of a polynomial are proposed. The presented methods are based on the fixed point relation of Laguerre's type and realized in ordinary complex arithmetic as well as circular complex interval arithmetic. The derived iterative formulas are suitable for the construction of modified methods with improved convergence rate with negligible additional operations. Very fast convergence of the considered methods is illustrated by two numerical examples

Pristup zasnovan na performansama u projektovanju prostornih struktura slobodne forme

This paper is related to the fact that use of computational tools for form generation, analysis and digital fabrication (CAD/CAM/CAE) in an efficient way enables accurate representation of ideas, simulation of diverse impact and production of rational design solutions. Application of geometrical and numerical computational methods and adoption of performance based priorities enables formal exploration in constrained conditions and improvement of architectural engineering design process. Implementation of advanced technologies in 3D digital design process facilitates production of unconventional complex designs, their verification by construction of physical models and experimental diagnostics, as phase preceding construction of real structure. Within this work concept that provides design of non-standard, context-specific, freeform structure using rapid prototyping technology and 3D optical measurement will be reviewed. The analyzed design solution of roof structure above atrium of National Museum in Belgrade has a function to demonstrate the effectiveness of this approach.Rad je povezan sa činjenicom da je korišćenjem alata za generisanje forme, analizu i digitalnu proizvodnju (CAD/CAM/CAE) na efikasan način omogućena precizna prezentacija ideja, simulacija različitih uticaja i produkcija racionalnih projektnih rešenja. Primena geometrijskih i numeričkih kompjuterskih metoda i usvajanja prioriteta zasnovanih na performansama omogućava formalna istraživanja u ograničenim uslovima i unapređenje procesa projektovanja u oblasti arhitektonskog inženjerstva. Implementacija naprednih digitalnih tehnologija u 3D proces projektovanja omogućava produkciju nekonvencionalnih kompleksnih oblika, njihovu verifikaciju konstrukcijom fizičkih modela i eksperimentalnu dijagnostiku, kao faze koja prethode izgradnji realne strukture. U okvirima ovog rada razmatraće se koncepti koji omogućavaju projektovanje nestandardne, kontekstualno specifične strukture slobodne forme primenom tehnologije brze proizvodnje prototipova i 3D optičkog merenje. Analizirano projektno rešenje krova iznad atrijuma Narodnog Muzeja u Beogradu u funkciji je potvrđivanja efikasnosti ovakvog pristupa

Traženje forme ljuski zasnovano na izogeometrijskoj analizi

The paper reviews potentials of the application of isogeometric analysis (IGA) in the pro­cesses of form-finding of shell structures. Shaping of those specific spatial structural typolo­gies is determined by consideration of the form-structure interrelation, therefore the sustainable approach to design implies application of form-finding techniques. In this paper, we applied the frequently used form-finding principle a inverted model strategy, more precisely concept of inverted displacements. Contrary to the similar studies which apply standard finite element (FE) discretization, we proposed an application of isogeometric modeling of the structure. Isogeome­try implies analysis based on the exact definition of the initial geometry, facilitating design and analysis by application on the single data type - model. Advantage of the conservation of geometric representation is especially evident in the case of shell structure designs, bearing in mind their continuously curved geometry. We applied NURBS based isogeometric analysis in which geometry and displacement field are described by NURBS surfaces. Modeling of the structural performances was conducted by isogeometric shell elements. Presented numerical experiment has a function to confirm the effectiveness of the proposed approach.Radom se razmatraju potencijali primene izogeometrijske analize u procesima traženja formi ljuski. Oblikovanje ovih specifičnih prostornih strukturalnih tipologija određeno je razmatranjem interrelacije forma-struktura, zbog čega održivi pristup njihovom projektovanju podra­zumeva primenu tehnika traženja forme. U okviru ovog rada primenjena je strategija obrnutog modela, često korišćen princip traženja forme, tačnije koncept obrnutih pomeranja. Za razliku od sličnih istraživanja u kojima se koristi standardna diskretizacija konačnim elementima (FE), ovim radom se predlaže izogeometrijsko modelovanje strukture. Izogeometrija podrazumeva analizu zasnovanu na egzaktnoj definiciji početne geometrije, čime je omogućeno projektovanje i analiza upotrebom jedinstvenog tipa podataka - modela. Prednost konzervacije geometrijske reprezentacije posebno dolazi do izražaja u slučaju projektovanja ljuski imajući u vidu njihovu kontinualno zakrivljenu geometriju. Primenjena je NURBS izogeometrijska analiza, u kojoj se geometrija i polje pomeranja opisuju korišćenjem NURBS površi. Modelovanje strukturalnih performansi izvršeno je korišćenjem izogeometrijskog elementa ljuske. Prikazan numerički ek­speriment u funkciji je potvrđivanja efikasnosti predloženog pristupa

A new higher-order family of inclusion zero-finding methods

AbstractStarting from a suitable fixed point relation, a new one-parameter family of iterative methods for the simultaneous inclusion of complex zeros in circular complex arithmetic is constructed. It is proved that the order of convergence of this family is four. The convergence analysis is performed under computationally verifiable initial conditions. An approach for the construction of accelerated methods with negligible number of additional operations is discussed. To demonstrate convergence properties of the proposed family of methods, two numerical examples results are given

Reverse biomimetic analogies in design of architectural structures

This paper explores the concept of reverse analogies in biomimetic design of architectural structures. Design paradigms based on biological models are engaged in appropriation of the biological forms, processes and terminology. They are grounded in multidisciplinary studies of modes of transposition and implementation of identified principles and natural laws in the discourse of spatial design with the goal of realization of optimal solutions that have certain desired attributes of the biological systems. On the other hand, reverse analogies are related to the application of concepts initially developed in architecture for research in different fields. It should be made distinction between nature as a source of explanation and source of inspiration. While in the context of natural sciences validity of the analogy is essentially important, in the case when the natural phenomena are used as a starting position for design research week form of analogy is tolerable. Even misinterpretations and heretical concepts could be simulative for design. The main advantage of the reverse analogies is in application of the freedom and liberal nature of the architecture that enables development of the concepts out of pure design reasons. Sometimes in the modelling of the phenomena not explained by the nature this approach could be simulative and catalytic. The goal of this paper is to exploit potentials of reverse analogies for deriving patterns or feedback data that can be used for conception and development of strategies and tools, or as an inspiration for formulation of intern morphological processes in design of architectural structures

Instrumentalization of origami in construction of folded plate structures: Design, research and education

The paper deals with the origami used as an abstract tool to describe and represent the form and the structure of physical objects. In that respect, the potentials of this interdisciplinary technique as a medium of exploration of structural forms was introduced in the semester project done within the course Structural Systems at the Belgrade University, Faculty of Architecture. The technique was used as an interface to gain cognitive experience on spatial transformation and computational design. Throughout the intensive project period divided into three successive stages, the objective was to test method which enabled students to analyze geometrical principles of folding in order to apply these principles in the development of new designs. The generative algorithm inspired by the technique of paper folding assisted form-finding. Resulting shapes were verified by a production of small scale prototype models. The applied method, as a guiding design principle, facilitated formal exploration and augmentation of the design process. At the end of the course, students got cognitive experience on structural forms, while this simple technique delivered richness in terms of design solutions

Analiza pristupačnosti strana u svrhu projektiranja modularnih naprava

This paper describes the methodology for the identification of accessibility of faces of 3D model of the workpiece, for the purpose of its positioning and clamping, by use of developed software application. Software application is developed in SolidWorks environment with the purpose to design modular fixtures. Using the SolidWorks API, MS Excel, object-oriented programming language Visual Basic 6 and logic in the form of production rules and algorithms, the development of software application was executed. Identification of the accessibility of faces of 3D model of the workpiece is based on the identification of characteristic coefficients and generation of their values. The coefficient of accessibility of faces appears as a final result of conducted analysis of face`s accessibility of the 3D model workpiece. The results gained from this software application are used to generate points for the positioning and clamping in the process of modular fixtures design. Developed software application provides mathematical notation of the face`s accessibility for the adopted conditions and restrictions, which was verified on the particular workpiece.Ovaj rad opisuje postupak za identificiranje pristupačnosti strana 3D modela radnog komada, u svrhu njegovog pozicioniranja i stezanja, korištenjem razvijene programske aplikacije. Programska aplikacija je razvijena u SolidWorks okružju u svrhu projektiranja modularnih naprava. Korištenjem SolidWorks API, MS Excel, objektno orijentiranog programskog jezika Visual Basic 6 i logike u obliku produkcijskih pravila i algoritama, izvršen je razvoj programske aplikacije. Identifikacija pristupačnosti strana 3D modela radnog komada bazira se na identifikaciji karakterističnih koeficijenata i generiranja njihovih vrijednosti. Koeficijent pristupačnosti strane se pojavljuje kao krajnji rezultat provedene analize pristupačnosti strane 3D modela radnog komada. Rezultati iz ove programske aplikacije koriste se za generiranje točaka za pozicioniranje i stezanje u procesu projektiranja modularnih naprava. Razvijena programska aplikacija daje matematički zapis pristupačnosti strane za usvojene uvjete i ograničenja, što je verificirano na konkretnom radnom predmetu

Formation analysis of Maglajci-Moštanica ophiolytic zones in the North of Kozara for the use of rocks in construction

Based on the field work and laboratory research, the basic geological characteristics of the ophiolitic melange of northern Kozara are presented, with an emphasis on the Maglajci ophiolitic block. Criteria for separations of formations were established and then applied in the analysis, especially those geologically directly recognizable in the field and outcrops, so one ore formation with two ore subformations was separated in the Maglajci block. In the central zone of block, the basalt outflows and diabase are dominant, while in the south of the block it is an outflow basaltic sequence of the ocean floor with the acidic differences of rhyolites and keratophyres. The second subformation also includes the Moštanica and Vojkova Bloc as a whole. The ore bearing formation is evaluated as a medium to low perspective formation, while parts of the Maglajci block with a massive to brecciated outflow are highly perspective terrain. There are rocks of good physical-mechanical characteristics and they meet the most requesting standards for road building. The results of formation analysis have denied a prior prognosis of ore bearing characteristics of this area, because it was thought that the ophiolitic blocks was built almost exclusively of diabase, and that the fields with those blocks are equally and good perspective for researching the deposits of construction stone

Maternal smoking during pregnancy and socioeconomic factors as predictors of low birth weight in term pregnancies in Niš

Background/Aim. Low birth weight (LBW) is a result of preterm birth or intrauterine growth retardation, and in both cases is the strongest single factor associated with perinatal and neonatal mortality. It is considered that socioeconomic factors, as well as mothers bad habits, play the most significant role in the development of LBW, which explains notable number of researches focused on this particular problem. The aim of this study was to characterize socioeconomic factors, as well as smoking habits of the mothers, and their connection with LBW. Methods. The questionnaire was carried out among mothers of 2 years old children (n = 956), born after 37 gestational weeks. The characteristics of mothers who had children with LBW, defined as < 2 500 g, (n = 50), were matched with the characteristics of mothers who had children ≥ 2 500 g, (n = 906). For defining risk factors, and protective factors as well, we used univariant and multivariant logistic modeles. Results. As significant risk factors for LBW in an univariant model we had education level of the mothers, smoking during pregnancy, smoking before pregnancy, the number of daily cigarettes, the number of cigarettes used during pregnancy, paternal earnings and socioeconomic factors. In a multivariant model the most significant factors were socioeconomic factors, education level of the mothers, paternal earnings and mothers smoking during pregnancy. Conclusion. Smoking during pregnancy and socioeconomic factors have great influence on LBW. Future studies should be carried out in different social groups, with the intention to define their influence on LBW and reproduction, as well. This should be the proper way of adequate health breeding planning for giving up smoking, the prevention of bad habits and melioration of mothers and children health, as the most vulnerable population

Influence of furnace tube shape on thermal strain of fire-tube boilers

The aim of this paper is to use numerical analysis and fine element method-FEM to investigate the influence of furnace tube shape on the thermal strain of fire-tube boilers. Thermal stresses in corrugated furnace tubes of different shape, i.e. with different corrugation pitch and depth, were analysed first. It was demonstrated that the thermal stresses in corrugated furnace tube are significantly reduced with the increase of corrugation depth. Than deformations and stresses in the structure of a fire-tube boiler were analysed in a real operating condition, for the cases of installed plain furnace tube and corrugated furnace tubes with different shapes. It was concluded that in this fire-tube boiler, which is of larger steam capacity, the corrugated furnace tube must be installed, as well as that the maximal stress in the construction is reduced by the installation of the furnace tube with greater corrugation depth. The analysis of stresses due to pressure and thermal loads pointed out that thermal stresses are not lower-order stresses in comparison to stresses due to pressure loads, so they must be taken into consideration for boiler strength analysis