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Crystal Indentation Hardness

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ISBN: 9783038429678 9783038429685 Year: Pages: VIII, 326
Publisher: MDPI - Multidisciplinary Digital Publishing Institute
Subject: Chemistry (General)
Added to DOAB on : 2018-07-05 12:27:53
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Dear Colleagues,Determinations of the indentation hardness properties of crystals have expanded to cover the full characterizations of their important elastic, plastic and cracking behaviors, particularly as accomplished with the increased measuring capabilities of nanoindentation hardness testing. No crystal structure of any bonding type is either too soft or too hard to prevent measurement with a suitable probing indenter. The current Special Issue is devoted to surveying the topic with emphasis given in a collection of reports to: (1) the diversity of crystals being tested; (2) the variety of measuring techniques; and (3) the wealth of information being obtained.Prof. Dr. Ron ArmstrongDr. Stephen WalleyProf. Dr. Wayne L. ElbanGuest Editors

Micromechanical modeling of short-fiber reinforced composites

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Book Series: Schriftenreihe Kontinuumsmechanik im Maschinenbau / Karlsruher Institut für Technologie, Institut für Technische Mechanik - Bereich Kontinuumsmechanik ISSN: 2192693X ISBN: 9783731504542 Year: Volume: 6 Pages: IX, 143 p. DOI: 10.5445/KSP/1000050760 Language: ENGLISH
Publisher: KIT Scientific Publishing
Subject: Technology (General)
Added to DOAB on : 2019-07-30 20:01:57
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This work is focused on the prediction of elastic behavior of short-fiber reinforced composites by mean-field homogenization methods, which account for experimentally determined and artificially constructed microstructure data in discrete and averaged form. The predictions are compared with experimental measurements and a full-field voxel-based approach. It is investigated, whether the second-order orientation tensor delivers a sufficient microstructure description for such predictions.

Optimierung der Energieeffizienz zweibeiniger Roboter durch elastische Kopplungen

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Book Series: Schriftenreihe des Instituts für Technische Mechanik, Karlsruher Institut für Technologie ISSN: 16143914 ISBN: 9783731502562 Year: Volume: 24 Pages: XV, 166 p. DOI: 10.5445/KSP/1000042846 Language: GERMAN
Publisher: KIT Scientific Publishing
Subject: Technology (General)
Added to DOAB on : 2019-07-30 20:01:57
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This work investigates the optimization of bipedal robots&#8217; energy efficiency by using elastic couplings. The regarded robots are modeled as underactuated systems and controlled by input-output linearization. To investigate the influence of elastic couplings on energy efficiency as well as stability and robustness the movements of the robots as well as their elastic couplings are simultaneously optimized using numerical algorithms.

Critical Earthquake Response of Elastic-Plastic Structures and Rigid Blocks under Near-Fault Ground Motions: Closed-Form Approach via Double Impulse

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Book Series: Frontiers Theme Book ISBN: 9782889198702 Year: Pages: 64 DOI: 10.3389/978-2-88919-870-2 Language: English
Publisher: Frontiers Media SA
Subject: General and Civil Engineering --- Environmental Engineering
Added to DOAB on : 2016-01-19 14:05:46
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This eBook is the second in a series of books on the critical earthquake response of elastic-plastic structures or rigid blocks under near-fault ground motions, and includes four original research papers which were published in the specialty section Earthquake Engineering in ‘Frontiers in Built Environment’. Several extensions of the first book1 are included here. The first article is on the soil-structure interaction problem. The reduction of an original soil-structure interaction model into a single-degree-of-freedom (SDOF) model enables the application of the original theory for an SDOF model to such complicated soil-structure interaction model. The second article is concerned with the extension of the original theory for an SDOF model to a 2DOF model. Since the simple application of the original theory for an SDOF model to a multi-degree-of-freedom model is difficult due to out-of-phase phenomenon of multiple masses, a convex model theory is introduced and an upper bound of elastic-plastic response is derived. The third article is related to the stability problem of structures (collapse problems of structures) in which the P-delta effect is included. It is shown that the original theory for an SDOF model with elastic-perfectly plastic restoring-force characteristic can be applied to a model with negative second slope. The fourth article is an application of the energy balance approach to an overturning limit problem of rigid blocks. A closed-form expression of the overturning limit of rigid blocks is derived for the first time after the Housner’s pioneering work in 1963. The approach presented in this book, together with the first book, is an epoch-making accomplishment to open the door for simpler and deeper understanding of structural reliability of built environments in the elastic-plastic and nonlinear range.

Critical Earthquake Response of Elastic-Plastic Structures Under Near-Fault Ground Motions: Closed-Form Approach via Impulse Input

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ISBN: 9782889197422 Year: Pages: 55 DOI: 10.3389/978-2-88919-742-2 Language: English
Publisher: Frontiers Media SA
Subject: General and Civil Engineering
Added to DOAB on : 2017-08-30 10:14:31
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The specialty section Earthquake Engineering is one branch of Frontiers in Built Environment and welcomes critical and in-depth submissions on earthquake ground motions and their effects on buildings and infrastructures. Manuscripts should yield new insights and ultimately contribute to a safer and more reliable design of building structures and infrastructures. The scope includes the characterization of earthquake ground motions (e.g. near-fault, far-fault, short-period, long-period), their underlying properties, their intrinsic relationship with structural responses, and the true behaviors of building structures and infrastructures under risky and uncertain ground motions. More specific topics include recorded ground motions, generated ground motions, response spectra, stochastic modeling of ground motion, critical excitation, geotechnical aspects, soil mechanics, soil liquefaction, soil-structure interactions, pile foundations, earthquake input energy, structural control, passive control, active control, base-isolation, steel structures, reinforced concrete structures, wood structures, building retrofit, structural optimization, uncertainty analysis, robustness analysis, and redundancy analysis. This eBook includes four original research papers, in addition to the Specialty Grand Challenge article, on the critical earthquake response of elastic-plastic structures under near-fault or long-duration ground motions which were published in the specialty section Earthquake Engineering. In the early stage of dynamic nonlinear response analysis of structures around 1960s, a simple hysteretic structural model and a simple sinusoidal earthquake ground motion input were dealt with together with random inputs. The steady-state response was tackled by an equivalent linearization method developed by Caughey, Iwan and others. In fact, the resonance plays a key role in the earthquake-resistant design and it has a strong effect even in case of near-fault ground motions. In order to draw the steady-state response curve and investigate the resonant property, two kinds of repetition have to be introduced. One is a cycle, for one forced input frequency, of the initial guess of the steady-state response amplitude, the construction of the equivalent linear model, the analysis of the steady-state response amplitude using the equivalent linear model and the update of the equivalent linear model based on the computed steady-state response amplitude. The other is the sweeping over a range of forced input frequencies. This process is quite tedious. Four original research papers included in this eBook propose a new approach to overcome this difficulty. Kojima and Takewaki demonstrated that the elastic-plastic response as continuation of free-vibrations under impulse input can be derived in a closed form by a sophisticated energy approach without solving directly the equations of motion as differential equations. While, as pointed out above, the approach based on the equivalent linearization method requires the repetition of application of the linearized equations, the method by Kojima and Takewaki does not need any repetition. The double impulse, triple impulse and multiple impulses enable us to describe directly the critical timing of impulses (resonant frequency) which is not easy for the sinusoidal and other inputs without a repetitive procedure. It is important to note that, while most of the previous methods employ the equivalent linearization of the structural model with the input unchanged, the method treated in this eBook transforms the input into a series of impulses with the structural model unchanged. This characteristic guarantees high accuracy and reliability even in the large plastic deformation range. The approach presented in this eBook is an epoch-making accomplishment to open the door for simpler and deeper understanding of structural reliability of built environments in the elastic-plastic range.

Crystal Chemistry of Zinc, Cadmium and Mercury

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ISBN: 9783038976523 Year: Pages: 156 DOI: 10.3390/books978-3-03897-653-0 Language: eng
Publisher: MDPI - Multidisciplinary Digital Publishing Institute
Subject: Organic Chemistry --- Chemistry (General) --- Science (General)
Added to DOAB on : 2019-04-05 10:34:31
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This book is a printed edition of the Special Issue Crystal Chemistry of Zinc, Cadmium and Mercury that was published in Crystals

First-Principles Prediction of Structures and Properties in Crystals

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ISBN: 9783039216703 / 9783039216710 Year: Pages: 128 DOI: 10.3390/books978-3-03921-671-0 Language: eng
Publisher: MDPI - Multidisciplinary Digital Publishing Institute
Subject: Science (General) --- Chemistry (General)
Added to DOAB on : 2019-12-09 16:10:12
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The term “first-principles calculations” is a synonym for the numerical determination of the electronic structure of atoms, molecules, clusters, or materials from ‘first principles’, i.e., without any approximations to the underlying quantum-mechanical equations. Although numerous approximate approaches have been developed for small molecular systems since the late 1920s, it was not until the advent of the density functional theory (DFT) in the 1960s that accurate “first-principles” calculations could be conducted for crystalline materials. The rapid development of this method over the past two decades allowed it to evolve from an explanatory to a truly predictive tool. Yet, challenges remain: complex chemical compositions, variable external conditions (such as pressure), defects, or properties that rely on collective excitations—all represent computational and/or methodological bottlenecks. This Special Issue comprises a collection of papers that use DFT to tackle some of these challenges and thus highlight what can (and cannot yet) be achieved using first-principles calculations of crystals.

Crystal Growth of Multifunctional Borates and Related Materials

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ISBN: 9783038978381 9783038978398 Year: Pages: 116 DOI: 10.3390/books978-3-03897-839-8 Language: eng
Publisher: MDPI - Multidisciplinary Digital Publishing Institute
Subject: Science (General) --- Physics (General)
Added to DOAB on : 2019-05-09 17:16:14
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Borate crystals are attractive for different technological applications because of their favorable physical and chemical properties like stability and high transparency, both high thermal and non-linear optical coefficients, making them ideal active media for highly efficient solid state lasers. In this Special Issue, different aspects of multifunctional borate crystals are discussed, including ortho- and oxyorthoborates and compounds with condensed anions, as well as their nonlinear optical and laser properties and piezoelectric characteristics. For this reason, complex investigations of the phase relationships in multi-component borate melts, the study of crystal growth conditions of novel high-temperature borates, and the development of the &ldquo;crystallization conditions, composition, structure, and properties&rdquo; concept will provide a scientific basis for growth technologies of high performance electronic and optical devices and components with a variety of industrial, medical and many other applications. In the meantime, these relationships can help to estimate the affinity of synthetic borate materials with their natural prototypes and structural analogues.

Tribology and Surface Engineering

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ISBN: 9783039280841 / 9783039280858 Year: Pages: 174 DOI: 10.3390/books978-3-03928-085-8 Language: eng
Publisher: MDPI - Multidisciplinary Digital Publishing Institute
Subject: General and Civil Engineering --- Technology (General)
Added to DOAB on : 2020-01-30 16:39:46
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Advances in Mechanical Problems of Functionally Graded Materials and Structures

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ISBN: 9783039216581 / 9783039216598 Year: Pages: 262 DOI: 10.3390/books978-3-03921-659-8 Language: eng
Publisher: MDPI - Multidisciplinary Digital Publishing Institute
Subject: Science (General) --- Mathematics
Added to DOAB on : 2019-12-09 11:49:16
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The book deals with novel aspects and perspectives in functionally graded materials (FGMs), which are advanced engineering materials designed for a specific performance or function with spatial gradation in structure and/or composition. The contributions mainly focus on numerical simulations of mechanical properties and the behavior of FGMs and FGM structures. Several advancements in numerical simulations that are particularly useful for investigations on FGMs have been proposed and demonstrated in this Special Issue. Such proposed approaches provide incisive methods to explore and predict the mechanical and structural characteristics of FGMs subjected to thermoelectromechanical loadings under various boundary and environmental conditions. The contributions have resulted in enhanced activity regarding the prediction of FGM properties and global structural responses, which are of great importance when considering the potential applications of FGM structures. Furthermore, the presented scientific scope is, in some way, an answer to the continuous demand for FGM structures, and opens new perspectives for their practical use.

Keywords

functionally graded beams --- different moduli in tension and compression --- bimodulus --- analytical solution --- neutral layer --- quadratic solid–shell elements --- finite elements --- functionally graded materials --- thin structures --- geometrically nonlinear analysis --- functionally graded piezoelectric materials --- circular plate --- combined mechanical loads --- electroelastic solution --- ANFIS --- fuzzy logic --- clustering --- neural networks --- robotics and contact wear --- evanescent wave --- polynomial approach --- functionally graded piezoelectric-piezomagnetic material --- dispersion --- attenuation --- functional graded saturated material --- inhomogeneity --- Love wave --- dispersion --- attenuation --- porous materials --- truncated conical sandwich shell --- metal foam core layer --- non-linear buckling analysis --- orthogonal stiffener --- elastic foundation --- functionally graded plate --- power-law distribution --- high order shear deformation theory --- elastic foundation --- stepped FG paraboloidal shell --- general edge conditions --- spring stiffness technique --- free vibration characteristics --- Lamb wave --- functionally graded viscoelastic material --- minimum module approximation method --- damping coefficient --- functionally graded materials --- finite element analysis --- graded finite elements --- functionally graded materials --- inhomogeneous composite materials --- material design --- stress concentration factor --- failure and damage --- elliptical hole --- finite element method --- hollow disc --- external pressure --- residual stress --- residual strain --- flow theory of plasticity --- functionally graded materials --- elastoplastic analysis --- pure bending --- residual stress --- large strain

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