Search results for "Geometry"
showing 10 items of 4487 documents
Effect of amorphous sequences on the longitudinal acoustic modes in partially crystalline polymers. I. Transfer matrix method
1983
A novel theoretical scheme is developed which enables the determination of the LAM-like vibrations of polymer chains made up of crystalline and amorphous parts as they occur in partially crystalline structures. The boundary conditions effective at the junction points are formulated in terms of the compliances of the associated amorphous sequences. These compliances can be derived from their eigenfrequencies and eigenvectors in a disconnected state. The treatment uses a matrix formalism which can be extended to include bending and torsional motions in a general state of vibration of the crystalline stem. A first numerical example demonstrates that the LA mode of a crystalline stem can be str…
Experimental Study of Vibrations in Face Milling Cutting
2014
Abstract The present paper consists in a comparison of vibrations measured during face milling cutting with two constructive variants of milling cutters (one with classic insert clamping and other with a quick insert adjustment mechanism). The goal of the study is to determine if the new clamping mechanism of the inserts has a similar behaviour with the classic one and can withstand milling conditions without introducing additional vibrations in the system
Survey of the Working Condition of Used Tractors in Northern Italy
1995
The working condition of 96 used tractors of different ages and sizes was examined in Northern Italy and compared with those of new machines and the standards at present in force. The results show that from the safety point of view, performance levels do not worsen drastically with increase in vehicle age. Rusty roll-over protective structures with cracks and tears are the main danger. Controls which are difficult to operate, seats in very bad condition, high levels of noise and vibrations render the situation critical from the ergonomic point of view.
Neutral and oxidized triisopropylsilyl end-capped oligothienoacenes: a combined electrochemical, spectroscopic, and theoretical study.
2010
This work presents an analy- sis of the structural, electrochemical, and optical properties of a family of triisopropylsilyl end-capped oligothie- noacenes (TIPS-Tn-TIPS, n = 4-8) by combining cyclic voltammetry, spectro- scopic techniques, and quantum-chemi- cal calculations. TIPS-Tn-TIPS com- pounds form stable radical cations, and dications are only obtained for the lon- gest oligomers (n = 7 and 8). Oxidation leads to the quinoidization of the con- jugated backbone, from which elec- trons are mainly extracted. The absorp- tion and fluorescence spectra show par- tially resolved vibronic structures even at room temperature, due to the rigid molecular geometry. Two well-resolved vibronic p…
Augstākā algebra: lekcijas, lasītas Latvijas Universitātes matemātikas un dabaszinātņu fakultātē
1936
Lekcijas sakārtojis Fogels, Ernests ; rediģējis Lūsis, Arvīds.
Masonry Sail Vaults in Maltese Architecture: Geometrical Analysis for the Study of Building Processes
2023
This research concerns the introduction and dissemination of masonry sail vaults in Malta between the sixteenth and the eighteenth centuries. A digital survey is produced to capture a reality-based 3D model, undertake analysis, and compare case studies with the aim of interpreting the sail vaults' construction systems.
Projective Architecture
2009
Sbacchi indaga su quale sia stata la reale influenza della nozione di "proiezione" nell'ambito della progettazione architettonica a partire da Guarini. Per fare ciò vengono presi in considerazione i concetti di luce e ombra così come quelli di linea astratta, piano, sezione, geometria proiettiva e prospettiva. Michele Sbacchi investigates the real influence of the notion of projection on architectural design before and during the age of Guarini. He takes into consideration concepts such as light and shadow, abstract line, plane, section, projective geometry and perspective. To do this he looks at the ideas of Gregorius Saint Vincent, Alberti, Guarini, Desargues and de l’Orme, among others.
Reversing arrows: Duality
2021
What do you get reversing all arrows? The drawing ‘Duality’ is an homage to mirrors, classical art themes, and abstract mathematics.I’m looking for beauty in the arts and beauty in science. It’s a ...
A Visual Introduction to Cubic Surfaces Using the Computer Software Spicy
2003
At the end of the 19th century geometers like Clebsch, Klein and Rodenberg constructed plaster models in order to get a visual impression of their surfaces, which are so beautiful from an abstract point of view. But these were static visualizations. Using the computer program Spicy 1, which was written by the second author, one can now draw algebraic curves and surfaces depending on parameters interactively.
GESTALT-INSPIRED FEATURES EXTRACTION FOR OBJECT CATEGORY RECOGNITION
2013
International audience; We propose a methodology inspired by Gestalt laws to ex- tract and combine features and we test it on the object cat- egory recognition problem. Gestalt is a psycho-visual the- ory of Perceptual Organization that aims to explain how vi- sual information is organized by our brain. We interpreted its laws of homogeneity and continuation in link with shape and color to devise new features beyond the classical proxim- ity and similarity laws. The shape of the object is analyzed based on its skeleton (good continuation) and as a measure of homogeneity, we propose self-similarity enclosed within shape computed at super-pixel level. Furthermore, we pro- pose a framework to …