scholarly journals Investigating the Effect of the Geometry of RC Barrier Walls on the Blast Wave Propagation

2021 ◽  
Vol 11 (3) ◽  
pp. 255-268
Author(s):  
Walid Attia ◽  
Sherif Elwan ◽  
Ismail Kotb
Keyword(s):  
Reinforced Concrete ◽  
Three Dimensional ◽  
Three Dimensions ◽  
Charge Weight ◽  
Variable Parameters ◽  
Research Goal ◽  
Blast Wave Propagation ◽  
Concrete Barrier ◽  
Barrier Wall ◽  
Better Than

Evaluating the performance of several types of reinforced concrete barrier walls subjected to blast loads is the target of this research paper. A parametric study is carried out for nine RC barrier wall systems with different geometries modelled in the three dimensions with different configurations and variable parameters. ANSYS Autodyn software version 18.2 is used to model and analyse these systems using three-dimensional explicit dynamics analysis. The nine systems are studied under the effect of several parameters, such as explosive charge weight (W) and the stand-off distance from the explosion source to the wall (R). Their effect on the wall damage and its deformations and the pressure-induced at different locations are analysed. Eighteen reinforced concrete barrier wall models are studied to achieve this research goal. Comparisons between the results showed the deformation performance of the 60° concave face with planar back walls and the walls with the constant base of 1.0-meter-thick up to 0.5-meter-high with a face hunch up to 2.0-meter-high are better than all other studied walls. However, the concave face-convex back wall that has 70° curvature mitigate the pressure behind the wall by 10% regardless of its deformation.

scholarly journals Fracture of Protective Structures from Heavy Reinforcing Cement During Interaction with High-velocity Impactor

2021 ◽  
Vol 14 (6) ◽  
pp. 779-786
Author(s):  
Pavel A. Radchenko ◽  
◽  
Stanislav P. Batuev ◽  
Andrey V. Radchenko
Keyword(s):  
Reinforced Concrete ◽  
High Velocity ◽  
Solid Mechanics ◽  
Three Dimensional ◽  
The Finite Element Method ◽  
Free Surfaces ◽  
Local Fracture Criterion ◽  
Protective Structures ◽  
Concrete Barrier ◽  
Limiting Value

In this work, the fracture of a reinforced concrete barrier made of heavy reinforced ce- ment is numerically simulated during normal interaction with a high-velocity titanium projectile. The projectile has the initial velocity 750 m/s. The problem of impact interaction is numerically solved by the finite element method in a three-dimensional formulation within a phenomenological framework of solid mechanics. Numerical modeling is carried out using an original EFES 2.0 software, which al- lows a straightforward parallelization of the numerical algorithm. Fracture of concrete is described by the Johnson-Holmquist model that includes the strain rate dependence of the compressive and tensile strengths of concrete. The computational algorithm takes into account the formation of discontinuities in the material and the fragmentation of bodies with the formation of new contact and free surfaces. The behavior of the projectile material is described by an elastoplastic medium. The limiting value of the plastic strain intensity is taken as a local fracture criterion for the projectile material. A detailed numerical analysis was performed to study the stress and strain dynamics of the reinforced concrete target and the effect of shock-wave processes on its fracture. The influence of reinforcement on the resistance of a heavy cement target to the penetration of a projectile has been investigated

scholarly journals 3D investigation of steel fiber distribution in reinforced concrete by X-ray microtomography

2015 ◽  
Vol 8 (5) ◽  
pp. 707-720 ◽  
Author(s):  
A. C. MACHADO ◽  
M. A. SILVA ◽  
R. D. T. FILHO ◽  
M. S. PFEIL ◽  
I. LIMA ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Reinforced Concrete ◽  
Three Dimensional ◽  
Absorption Capacity ◽  
Steel Fibers ◽  
Three Dimensions ◽  
Morphological Properties ◽  
X Ray ◽  
Brittle Behavior ◽  
Computed Microtomography

ABSTRACTThe effects of the inclusion of steel fibers in concrete have been widely studied in order to investigate possible changes in mechanical properties, such as the increase in tensile strength, ductility, stiffness, toughness (energy absorption capacity), and durability. An immediate consequence of this addition is the mitigation of concrete's brittle behavior, so that the material meets new quality requirements. In this context, it is important to study the spatial distribution of the entire internal structure of these materials. Three-dimensional computed microtomography is a non-destructive inspection technique used to characterize the internal structures of various materials based on X-ray interaction with the inspected object. Topological and morphological properties can be obtained directly in three dimensions by means of mathematical reconstruction of the radiographs, which allows analyzing, for example, porosity and distribution of objects. In this context, the aim of this study is to investigate the spatial distribution of steel fibers, as well as of porosity in reinforced concrete samples. To this end, we used a microtomography system calibrated to operate at a voltage of 80 kV, electric current of 100 μA and a pixel size equal to 24 µm. The results showed low porosity and that the steel fibers were not uniformly distributed throughout the sample.

On Mental Rotation in Three Dimensions

1997 ◽  
Vol 85 (1) ◽  
pp. 297-298 ◽  
Author(s):  
W. McWilliams ◽  
C. J. Hamilton ◽  
S. J. Muncer
Keyword(s):  
Mental Rotation ◽  
Sex Difference ◽  
Three Dimensional ◽  
Three Dimensions ◽  
Dimensional Models ◽  
Three Dimensional Images ◽  
Three Dimensional Models ◽  
Better Than

Real three-dimensional models and three-dimensional images were used in a test of mental rotation. Although the 33 men performed better than the 33 women when presented three-dimensional images (14.4 and 11.2), this sex difference disappeared when real models were used (17.5 and 17.3).

scholarly journals Reflecting theology by a generic model of research designs? Impulses from religious didactics

2021 ◽  
Vol 77 (2) ◽  
Author(s):  
Martin Rothgangel ◽  
Ulrich Riegel
Keyword(s):  
Dimensional Space ◽  
Social Systems ◽  
Three Dimensional ◽  
Three Dimensions ◽  
Generic Model ◽  
Present Contribution ◽  
Essential Point ◽  
Research Designs ◽  
The Face ◽  
Research Goal

A look at history showed that theology always has to face contemporary demands in terms of its scientific character. At present, processes of pluralisation and secularisation challenge the existence of theology at universities not only against the background of religious studies, which are independent of the churches, but also, for example, in relation to innovative life sciences or cognitive sciences. In this context, an essential point to consider was that theology – like social systems in general and science in particular – is characterised by an increasing differentiation. This differentiation of science implied an increasing specialisation of research, which could also be observed in the field of theology and its sub-disciplines. This article accordingly addressed the question of how, in the face of increasingly specialised research studies, the unity of theology can be justified beyond abstract and sweeping determinations. The present contribution suggested that in this respect a model of research designs developed in religious didactics might prove useful. This model of research design could essentially be understood as consisting of three research dimensions (topics, reference theories and methodologies) that define a research space, in which the research study on the didactics of religion can be located in the three-dimensional space by the research goal as a formatting factor. The three dimensions of this model (topics, reference theories and methodologies), including the research goal, seemed to be broad enough to be tested in other sub-disciplines of theology as well to see whether their research can be more closely defined with them.Contribution: Accordingly, the contribution of this article was to raise the question, in view of an increasing specialisation of theological research, to what extent a model of research designs developed in the didactics of religion could be transferred to other sub-disciplines of theology. Should this succeed a new approach to justifying the unity of theology could become available, which is able to take into account the current differentiation of theology.

convergent-beam diffraction from surfaces

1987 ◽  
Vol 45 ◽  
pp. 30-33
Author(s):  
J. A. Eades ◽  
A. E. Smith ◽  
D. F. Lynch
Keyword(s):  
Reciprocal Lattice ◽  
Three Dimensional ◽  
Grazing Incidence ◽  
Three Dimensions ◽  
Plane Figure ◽  
Transmission Electron ◽  
Convergent Beam ◽  
Beam Patterns ◽  
Beam Diffraction

It is quite simple (in the transmission electron microscope) to obtain convergent-beam patterns from the surface of a bulk crystal. The beam is focussed onto the surface at near grazing incidence (figure 1) and if the surface is flat the appropriate pattern is obtained in the diffraction plane (figure 2). Such patterns are potentially valuable for the characterization of surfaces just as normal convergent-beam patterns are valuable for the characterization of crystals.There are, however, several important ways in which reflection diffraction from surfaces differs from the more familiar electron diffraction in transmission.GeometryIn reflection diffraction, because of the surface, it is not possible to describe the specimen as periodic in three dimensions, nor is it possible to associate diffraction with a conventional three-dimensional reciprocal lattice.

Exploring the Multidimensional Facets of Authoritarianism: Authoritarian Aggression and Social Dominance Orientation

2008 ◽  
Vol 67 (1) ◽  
pp. 51-60 ◽  
Author(s):  
Stefano Passini
Keyword(s):  
Social Dominance ◽  
Factor Model ◽  
Three Dimensional ◽  
Social Dominance Orientation ◽  
Model Fit ◽  
Regression Analyses ◽  
One Dimensional ◽  
Confirmatory Factor ◽  
The One ◽  
Better Than

The relation between authoritarianism and social dominance orientation was analyzed, with authoritarianism measured using a three-dimensional scale. The implicit multidimensional structure (authoritarian submission, conventionalism, authoritarian aggression) of Altemeyer’s (1981, 1988) conceptualization of authoritarianism is inconsistent with its one-dimensional methodological operationalization. The dimensionality of authoritarianism was investigated using confirmatory factor analysis in a sample of 713 university students. As hypothesized, the three-factor model fit the data significantly better than the one-factor model. Regression analyses revealed that only authoritarian aggression was related to social dominance orientation. That is, only intolerance of deviance was related to high social dominance, whereas submissiveness was not.

Extension of the Spatial PDI Model to Three Dimensions

1997 ◽  
Vol 84 (1) ◽  
pp. 176-178
Author(s):  
Frank O'Brien
Keyword(s):  
Population Density ◽  
Dimensional Space ◽  
Finite Lattice ◽  
Three Dimensional ◽  
Upper Bounds ◽  
Three Dimensions ◽  
Lower And Upper Bounds ◽  
Density Index ◽  
Three Dimensional Space

The author's population density index ( PDI) model is extended to three-dimensional distributions. A derived formula is presented that allows for the calculation of the lower and upper bounds of density in three-dimensional space for any finite lattice.

A Three-Dimensional Tetraphenylethylene-Based Fluorescence Covalent Organic Framework for Molecular Recognition

2020 ◽  
Author(s):  
Junxia Ren ◽  
Yaozu Liu ◽  
Xin Zhu ◽  
Yangyang Pan ◽  
Yujie Wang ◽  
...  
Keyword(s):  
Molecular Recognition ◽  
Fluorescence Probe ◽  
Three Dimensional ◽  
Hazardous Substances ◽  
Covalent Organic Framework ◽  
Highly Sensitive ◽  
Volatile Organic ◽  
Polycyclic Aromatic ◽  
Better Than ◽  
Organic Framework

<p><a></a><a></a><a></a><a></a><a></a><a></a><a></a><a>The development of highly-sensitive recognition of </a><a></a><a></a><a></a><a></a><a>hazardous </a>chemicals, such as volatile organic compounds (VOCs) and polycyclic aromatic hydrocarbons (PAHs), is of significant importance because of their widespread social concerns related to environment and human health. Here, we report a three-dimensional (3D) covalent organic framework (COF, termed JUC-555) bearing tetraphenylethylene (TPE) side chains as an aggregation-induced emission (AIE) fluorescence probe for sensitive molecular recognition.<a></a><a> </a>Due to the rotational restriction of TPE rotors in highly interpenetrated framework after inclusion of dimethylformamide (DMF), JUC-555 shows impressive AIE-based strong fluorescence. Meanwhile, owing to the large pore size (11.4 Å) and suitable intermolecular distance of aligned TPE (7.2 Å) in JUC-555, the obtained material demonstrates an excellent performance in the molecular recognition of hazardous chemicals, e.g., nitroaromatic explosives, PAHs, and even thiophene compounds, via a fluorescent quenching mechanism. The quenching constant (<i>K</i><sub>SV</sub>) is two orders of magnitude better than those of other fluorescence-based porous materials reported to date. This research thus opens 3D functionalized COFs as a promising identification tool for environmentally hazardous substances.</p>

scholarly journals Free partition functions and an averaged holographic duality

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Nima Afkhami-Jeddi ◽  
Henry Cohn ◽  
Thomas Hartman ◽  
Amirhossein Tajdini
Keyword(s):  
Partition Function ◽  
Spectral Gap ◽  
Central Charge ◽  
Three Dimensional ◽  
Two Dimensions ◽  
Three Dimensions ◽  
Partition Functions ◽  
General Constraints ◽  
Dimensional Gravity ◽  
Holographic Duality

Abstract We study the torus partition functions of free bosonic CFTs in two dimensions. Integrating over Narain moduli defines an ensemble-averaged free CFT. We calculate the averaged partition function and show that it can be reinterpreted as a sum over topologies in three dimensions. This result leads us to conjecture that an averaged free CFT in two dimensions is holographically dual to an exotic theory of three-dimensional gravity with U(1)c×U(1)c symmetry and a composite boundary graviton. Additionally, for small central charge c, we obtain general constraints on the spectral gap of free CFTs using the spinning modular bootstrap, construct examples of Narain compactifications with a large gap, and find an analytic bootstrap functional corresponding to a single self-dual boson.

Sign in / Sign up

Export Citation Format

Share Document