NONLOCAL CONTINUUM ADAPTIVE ELASTIC BONE-COLUMN BUCKLING MODEL

2021 ◽  
Vol 21 (03) ◽  
pp. 2150015
Author(s):  
H. BENNACEUR ◽  
S. RAMTANI ◽  
T. OUTTAS ◽  
T. BOUKHAROUBA
Keyword(s):  
Bone Density ◽  
Beam Theory ◽  
Point Of View ◽  
Theoretical Point ◽  
Column Buckling ◽  
Strength Based ◽  
Buckling Failure ◽  
Euler Bernoulli Beam ◽  
Clinical Problems ◽  
Made In

It is well argued that stability-initiated failure dominates, especially in older bone, because of the instability of single trabeculae which is prone to inelastic buckling at stresses far less than expected for strength-based failure. It is also well known that when several horizontal struts have disappeared, trabecula fails due to compression-buckling load. In this contribution, our main goal is to improve, from theoretical point of view, the mechanistic understanding of bone buckling failure which is known to be at the core of important clinical problems. For that and with respect to previous works, an attempt is made in order to establish a simplified adaptive-beam buckling model, formulated within the context of the nonlocal adaptive continuum mechanics, from which numerical computations were performed in order to get a better knowledge about bone-column buckling mechanism affected by both bone density and bone density gradient distributions restricted to Euler–Bernoulli beam theory. An attempt is made to compare the experimental data with the response of our simplified model. For that, controlled buckling tests of single trabeculae were carried out from three medial tibia end sections (knee joint).

scholarly journals Influence of sample slenderness and boundary conditions in triaxial test - a review

2019 ◽  
Vol 92 ◽  
pp. 02009
Author(s):  
Elena Peri ◽  
Lars Bo Ibsen ◽  
Benjaminn Nordahl Nielsen
Keyword(s):  
Boundary Conditions ◽  
Triaxial Test ◽  
Point Of View ◽  
Single Line ◽  
Triaxial Testing ◽  
Theoretical Point ◽  
Test Configuration ◽  
Fem Modelling ◽  
The Past ◽  
Made In

In the past decades an extensive work was done in order to improve the performance and increase the reliability of triaxial testing. Among the several changes made in order to solve the inaccuracies of the traditional test configuration, two of them are discussed in this paper: the sample slenderness [in other words, the H/D ratio] and the introduction of smooth end platens instead of the rough ones. By using H/D=1 and not the usual H/D=2 ratio, the formation of a single line-rapture and the bulge shape seem prevented. The smooth ends decrease the restrain at the top and bottom of the sample. From a theoretical point of view the effects of these changes are clear, but experimentally, the results coming from various studies are contradictory. The purpose of this paper is to elucidate the previous findings on the topic, including both laboratory and FEM modelling test programs.

scholarly journals An Empirical Review of Automated Machine Learning

Computers ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 11
Author(s):  
Lorenzo Vaccaro ◽  
Giuseppe Sansonetti ◽  
Alessandro Micarelli
Keyword(s):  
Machine Learning ◽  
Computer Science ◽  
Research Work ◽  
Industrial Sector ◽  
Point Of View ◽  
Future Research ◽  
Theoretical Point ◽  
Academic Field ◽  
Automated Machine Learning ◽  
Made In

In recent years, Automated Machine Learning (AutoML) has become increasingly important in Computer Science due to the valuable potential it offers. This is testified by the high number of works published in the academic field and the significant efforts made in the industrial sector. However, some problems still need to be resolved. In this paper, we review some Machine Learning (ML) models and methods proposed in the literature to analyze their strengths and weaknesses. Then, we propose their use—alone or in combination with other approaches—to provide possible valid AutoML solutions. We analyze those solutions from a theoretical point of view and evaluate them empirically on three Atari games from the Arcade Learning Environment. Our goal is to identify what, we believe, could be some promising ways to create truly effective AutoML frameworks, therefore able to replace the human expert as much as possible, thereby making easier the process of applying ML approaches to typical problems of specific domains. We hope that the findings of our study will provide useful insights for future research work in AutoML.

An INDO investigation of the bonding modes occurring in five-membered heterocyclic thiones

1986 ◽  
Vol 64 (11) ◽  
pp. 2225-2228
Author(s):  
George Kapsomenos ◽  
Pericles Akrivos
Keyword(s):  
Experimental Data ◽  
Metal Ions ◽  
Point Of View ◽  
Theoretical Point ◽  
Simultaneous Presence ◽  
Indo Method ◽  
Heterocyclic Thiones ◽  
Ph Dependent ◽  
Semi Empirical ◽  
Made In

A group of five-membered heterocyclic thioketo-compounds is studied by using results derived from the semi-empirical INDO method. The interest of these compounds from a theoretical point of view is the simultaneous presence of both sulfur and nitrogen in active positions so that a diversity of bonding schemes with metal ions could be encountered. The prediction of these coordination aspects are here explained quite satisfactorily by means of the computed HOMO eigenvalues of the ligands and by application of the energy-based HSAB criterion. This criterion is applied in cases where the coordination is not strongly pH dependent and the appropriate ligand form is considered. The straightforward derivation of the conclusions allows predictions of the bonding subtleties to be made in cases where experimental data are lacking or insufficient for clear conclusions.

scholarly journals Joint Discussion 11: The Lithium Problem Introduction

1995 ◽  
Vol 10 ◽  
pp. 437-438
Author(s):  
F. Spite
Keyword(s):  
Difficult Problem ◽  
Point Of View ◽  
General Assembly ◽  
Theoretical Point ◽  
Essential Information ◽  
Primordial Nucleosynthesis ◽  
Points Of Interest ◽  
The World ◽  
Interstellar Material ◽  
Made In

The exact title of the JD 11 was: “stellar and interstellar lithium and primordial nucleosynthesis”. The large amount of work recently done about lithium provided an incentive for a discussion among the members of several commissions of the IAU. Lithium is a peculiar element. Since it is not produced in supernovae (at least such a production is not proven and would be quite different from the production of the other elements) its presence in old material is a legacy of the primordial nucleosynthesis. But lithium is a fragile element, and from a theoretical point of view, there are arguments tending to conclude that, in old stars, this legacy has been depleted. This difficult problem is areal challenge, an has been the motivation for many different works. The analysis of the lithium behavior in well known stars, of all kind of ages, metallicities, structures, peculiarities etc. is therefore extremely useful in order to understand the physicalprocesse at work for lithium depletion, and the reader will find here many up-to-date data. The analysis of lithium in interstellar material provides an essential information. Many works about lithium are in progress throughout the world on the different points of interest, so that the General Assembly of the IAU was an excellent occasion to have a review of the recent progresses made in different areas. A summary of (nearly) each communication made during the Joint Discussion 11 may be found hereafter. Longer summaries of the talks, and summaries of the posters will be published in a forthcoming volume of the Memorie of the Società Astronomica Italiana.

scholarly journals XIX. Discussion of the magnetical observations made by captain Back, R. N. during his late arctic expedition

1836 ◽  
Vol 126 ◽  
pp. 377-415
Keyword(s):  
Royal Society ◽  
Point Of View ◽  
Minor Importance ◽  
Theoretical Point ◽  
Terrestrial Magnetism ◽  
Primary Object ◽  
More Care ◽  
Magnetic Needle ◽  
Made In

Previous to Captain Back’s departure in 1833 with the expedition for the relief of Captain Ross, he consulted me respecting the nature of the magnetical observations which I considered it desirable should be made in the regions he was likely to visit. I was fully sensible that, however available the expedition on which he had so nobly volunteered might be made to the cause of science, its primary object, and that to which all others must give place, was the relief of our gallant countrymen, at that time considered to be in imminent danger of perishing in the inhospitable regions which their enterprising spirit had led them to explore. I therefore considered it an object of the first importance, that whatever observations were to be made during the movements of the expedition should be so conducted as to cause as little delay as possible consistently with obtaining data for correct results, and also, that they should be made in the order of their importance. Compared with observations of the direction of the magnetic needle, both with reference to the meridian and to the vertical, other observations are of minor importance towards establishing anything like a theory of terrestrial magnetism. Considering that observations of the direction of the needle with reference to the meridian, though quite as important in a theoretical point of view as those with regard to the vertical, were necessarily called for in the conducting of the expedition, I, in the first instance, pointed out the observations which I considered necessary for determining the dip of the needle at the various stations where it might be practicable to make such observations; and I left the less important ones for the determination of the relative intensities of the absolute force acting upon the needle, which required more care, attention and assistance, to be made or not, according to the circumstances under which the expedition might be placed. Immediately on his return, Captain Back did me the favour to place all his magnetical observations at my disposal, and I feel that I should not do justice to the zeal and ability which that enterprising officer has displayed in the cause of science, if I did not, now that I have had leisure to reduce the observations, lay an account of them before the Royal Society.

Specimen Preparation for Clinical Applications of X-Ray Microanalysis

1990 ◽  
Vol 48 (2) ◽  
pp. 328-329
Author(s):  
J.D. Shelburne ◽  
G.M. Roomans
Keyword(s):  
Carbon Coating ◽  
Clinical Applications ◽  
Point Of View ◽  
Practical Significance ◽  
Sweat Test ◽  
Specimen Preparation ◽  
Tissue Preparation ◽  
X Ray ◽  
Gallbladder Stones ◽  
Clinical Problems

Proper preparative procedures are a prerequisite for the validity of the results of x-ray microanalysis of biological tissue. Clinical applications of x-ray microanalysis are often concerned with diagnostic problems and the results may have profound practical significance for the patient. From this point of view it is especially important that specimen preparation for clinical applications is carried out correctly.Some clinical problems require very little tissue preparation. Hair, nails, and kidney and gallbladder stones may be examined and analyzed after carbon coating. High levels of zinc or copper in hair may be indicative of dermatological or systemic diseases. Nail clippings may be analyzed (as an alternative to the more conventional sweat test) to confirm a diagnosis of cystic fibrosis. X-ray microanalysis in combination with scanning electron microscopy has been shown to be the most reliable method for the identification of the components of kidney or gallbladder stones.A quantitatively very important clinical application of x-ray microanalysis is the identification and quantification of asbestos and other exogenous particles in lung.

Timber Auctions in the Context of the Modern Auction Theory

2007 ◽  
pp. 86-94
Author(s):  
A. Manakov
Keyword(s):  
Theoretical Analysis ◽  
Auction Theory ◽  
Point Of View ◽  
Theoretical Point ◽  
English Auction ◽  
Analysis And Evaluation

The article provides theoretical analysis and evaluation of the timber auctions reforms in Russia. The author shows that the mechanism of the "combined auctions", which functioned until recently, is more appropriate from the theoretical point of view (and from the point of view of the Russian practice) as compared to the officially approved format of the English auction.

BIO-ENERGY FROM PHOTOSYNTHETIC ALLOYS FOR USE IN BIOGUALS AND BIOPRODUCTS

2019 ◽  
pp. 613-618
Author(s):  
Petar Kazakov ◽  
Atanas Iliev ◽  
Emil Ivanov ◽  
Dobri Rusev
Keyword(s):  
Technical Progress ◽  
Point Of View ◽  
Energy Sustainability ◽  
International Activities ◽  
Made In

Significant technical progress has been made in recent years in the development of algae-based bioenergy, and much of industrial and academic R&D projects have diverged from the biofuels strategy. This report summarizes the conclusions of a recently concluded symposium analyzing the prospects for using micro- and macroalgae as a feedstock for biofuels and bioenergy. It discusses international activities for the development of bio-energy and non-energy algae bioproducts, advances in the use of macroalgae (both non-cultivated and cultivated algae). Applications for various biochemical and thermochemical uses, bio-refining capabilities for various products, as well as an in-depth review of the process from the point of view of economy and energy sustainability are also given.

A novel cryptosystem based on abstract automata and Latin cubes

2015 ◽  
Vol 52 (2) ◽  
pp. 221-232
Author(s):  
Pál Dömösi ◽  
Géza Horváth
Keyword(s):  
Block Cipher ◽  
Finite Automata ◽  
Theoretical Background ◽  
Point Of View ◽  
Theoretical Point ◽  
Transition Matrices ◽  
Encryption And Decryption ◽  
Secret Keys ◽  
Automata Network ◽  
Fully Functioning

In this paper we introduce a novel block cipher based on the composition of abstract finite automata and Latin cubes. For information encryption and decryption the apparatus uses the same secret keys, which consist of key-automata based on composition of abstract finite automata such that the transition matrices of the component automata form Latin cubes. The aim of the paper is to show the essence of our algorithms not only for specialists working in compositions of abstract automata but also for all researchers interested in cryptosystems. Therefore, automata theoretical background of our results is not emphasized. The introduced cryptosystem is important also from a theoretical point of view, because it is the first fully functioning block cipher based on automata network.

Graffiti als Version und Subversion–Praxen kultureller Re-Regulierung und die Möglichkeit von Gratiforschung

2010 ◽  
Vol 55 (2) ◽  
pp. 11-25 ◽  
Author(s):  
Bernd Dollinger
Keyword(s):  
Social Life ◽  
Point Of View ◽  
Theoretical Point ◽  
Research Practice ◽  
Wird Eine ◽  
Multiple Perspectives

Der Beitrag geht von Versuchen aus, integrative Perspektiven einer überaus heterogenen Graffitiforschung zu bestimmen. In Auseinandersetzung insbesondere mit Bruno Latours Ansatz des »Iconoclash« wird eine kulturtheoretische Referenz bestimmt, die Graffiti als Version identifiziert, d. h. als semiotisch orientierte Veränderung räumlich situierter Ordnungs- und Regulierungspraxen. Ihnen kann, wenn auch nicht zwingend, eine subversive Qualität zukommen. Durch die Ausrichtung am Konzept einer Version wird beansprucht, Forderungen einer normativ weitgehend abstinenten, nicht-essentialistischen und für komplexe Fragen der Identitäts- und Raumpolitik offenen Forschungspraxis einzulösen.<br><br>The contribution attempts to integrate multiple perspectives of current largely heterogeneous graffiti scholarship. Referring to Bruno Latour’s concept »iconoclash«, we discuss graffiti from a cultural-theoretical point of view as a »version«. It appears as a semiotically oriented modification of spatially situated practices that regulate social life. Often, but not necessarily, these practices involve subversive qualities. The concept of »version« facilitates a non-normative and non-essentialist strategy of research. This enables an explorative research practice in which the complex matters of identity and space politics that are associated with graffiti can be addressed.

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