scholarly journals A Numerical Study on 3D Printed Cementitious Composites Mixes Subjected to Axial Compression

Materials ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 6882
Author(s):  
Hanqiu Liu ◽  
King-James Idala Egbe ◽  
Haipeng Wang ◽  
Ali Matin Nazar ◽  
Pengcheng Jiao ◽  
...  
Keyword(s):  
Numerical Study ◽  
Functionally Graded ◽  
Cementitious Composites ◽  
Recent Developments ◽  
3D Printed ◽  
Material Volume ◽  
Functionally Graded Structure ◽  
Good Agreement ◽  
Layer Position

Aptly enabled by recent developments in additive manufacturing technology, the concept of functionally grading some cementitious composites to improve structural compression forms is warranted. In this work, existing concrete models available in Abaqus Finite Element (FE) packages are utilized to simulate the performance of some cementitious composites numerically and apply them to functional grading using the multi-layer approach. If yielding good agreement with the experimental results, two-layer and three-layer models case combinations are developed to study the role of layer position and volume. The optimal and sub-optimal performance of the multi-layer concrete configurations based on compressive strength and sustained strains are assessed. The results of the models suggest that layer volume and position influence the performance of multi-layer concrete. It is observed that when there exists a substantial difference in material strengths between the concrete mixes that make up the various layers of a functionally graded structure, the influence of position and of material volume are significant in a two-layer configuration. In contrast, in a three-layer configuration, layer position is of minimal effect, and volume has a significant effect only if two of the three layers are made from the same material. Thus, a multilayered design approach to compression structures can significantly improve strength and strain performance. Finally, application scenarios on some structural compression forms are shown, and their future trajectory is discussed.

Experimental and Numerical Study of the Cavitating Flow on a Hydrofoil

2003 ◽  
Author(s):  
O. Coutier-Delgosha ◽  
J.-F. Devillers
Keyword(s):  
Void Ratio ◽  
Numerical Study ◽  
Oscillatory Behavior ◽  
Cavitating Flow ◽  
Vapor Cavity ◽  
First Results ◽  
Recent Developments ◽  
Flow Configurations ◽  
Good Agreement ◽  
Unsteady Cavitating Flow

The unsteady cavitating flow field on a 2D hydrofoil is investigated by experimental means and numerical calculations. The self-oscillatory behavior of the cavitation sheet observed experimentally is correctly simulated by the numerical model. A particularly good agreement is obtained concerning the frequency of the phenomenon in various flow configurations. To confirm the low void ratio predicted by the model in the main part of the liquid/vapor cavity a new experimental device is applied: it is based on an endoscopic visualization of the interior of the mixture. Recent developments of the method are presented, and some first results are analysed.

Prandtl Number Effect on Be´nard Convection in Porous Media

1986 ◽  
Vol 108 (2) ◽  
pp. 284-290 ◽  
Author(s):  
J. G. Georgiadis ◽  
I. Catton
Keyword(s):  
Energy Equation ◽  
Nonequilibrium Thermodynamics ◽  
Numerical Study ◽  
Laboratory Data ◽  
Two Dimensional ◽  
Average Temperature ◽  
The Mean ◽  
Convection In Porous Media ◽  
Good Agreement

A numerical study of buoyancy-driven two-dimensional convection in a fluid-saturated horizontal porous layer is reported emphasizing the nonlinear inertial effect on heat transport. The Forchheimer–Brinkman–Darcy–Boussinesq formulation and a single energy equation for the volume-average temperature are used. Closure to the wavenumber selection problem is sought through a criterion based on the Glansdorff and Prigogine theory of nonequilibrium thermodynamics. Good agreement with laboratory data and the analogy with the Rayleigh–Be´nard problem are corroborative facts which justify similar non-Darcian formulations and demonstrate the role of the quadratic inertial terms in decreasing the mean convective heat transfer across the layer.

How do histone modifications contribute to transgenerational epigenetic inheritance in C. elegans?

2020 ◽  
Vol 48 (3) ◽  
pp. 1019-1034 ◽  
Author(s):  
Rachel M. Woodhouse ◽  
Alyson Ashe
Keyword(s):  
Histone Modifications ◽  
Molecular Mechanisms ◽  
Epigenetic Inheritance ◽  
Nematode Caenorhabditis Elegans ◽  
Histone Methyltransferases ◽  
Transgenerational Epigenetic Inheritance ◽  
C Elegans ◽  
Recent Developments ◽  
Gene Regulatory

Gene regulatory information can be inherited between generations in a phenomenon termed transgenerational epigenetic inheritance (TEI). While examples of TEI in many animals accumulate, the nematode Caenorhabditis elegans has proven particularly useful in investigating the underlying molecular mechanisms of this phenomenon. In C. elegans and other animals, the modification of histone proteins has emerged as a potential carrier and effector of transgenerational epigenetic information. In this review, we explore the contribution of histone modifications to TEI in C. elegans. We describe the role of repressive histone marks, histone methyltransferases, and associated chromatin factors in heritable gene silencing, and discuss recent developments and unanswered questions in how these factors integrate with other known TEI mechanisms. We also review the transgenerational effects of the manipulation of histone modifications on germline health and longevity.

Wilfred Ethier. Modern International Economics. New York: W. W. Norton and Company. 1983. xviii + 588 pp.

1988 ◽  
Vol 27 (1) ◽  
pp. 81-83
Author(s):  
Nadeem A. Burney
Keyword(s):  
International Economic ◽  
New York ◽  
Economic Theory ◽  
International Economics ◽  
International Monetary System ◽  
International Markets ◽  
The Past ◽  
Monetary System ◽  
Recent Developments

Its been long recognized that various economies of the world are interlinked through international trade. The experience of the past several years, however, has demonstrated that this economic interdependence is far greater than was previously realized. In this context, the importance of international economic theory as an area distinct from general economics hardly needs any mentioning. What gives international economic theory this distinction is international markets for some goods and effects of national sovereignty on the character of economic activity. Wilfred Ethier's book, which incorporates recent developments in the field, is an excellent addition to textbooks on international economics for one- or twosemester undergraduate courses. The book mostly covers standard topics. A distinguishing feature of this book is its detailed analysis of the flexible exchange rates and a discussion of the various approaches used for their determination. Within each chapter, the author has extensively used facts, figures and major events to clarify the concepts in the light of the theoretical framework. The book also discusses, in a fair amount of detail, the existing international monetary system and the role of various international organizations.

The Role of Financial Innovation in EU Market Integration and the Capital Markets Union

2018 ◽  
Author(s):  
Emilios Avgouleas
Keyword(s):  
Capital Markets ◽  
Risk Sharing ◽  
Market Integration ◽  
Financial Innovation ◽  
The European Union ◽  
Recent Developments ◽  
Capital Markets Union ◽  
Critical Overview ◽  
The Eu

This chapter offers a critical overview of the issues that the European Union 27 (EU-27) will face in the context of making proper use of financial innovation to further market integration and risk sharing in the internal financial market, both key objectives of the drive to build a Capital Markets Union. Among these is the paradigm shift signalled by a technological revolution in the realm of finance and payments, which combines advanced data analytics and cloud computing (so-called FinTech). The chapter begins with a critical analysis of financial innovation and FinTech. It then traces the EU market integration efforts and explains the restrictive path of recent developments. It considers FinTech's potential to aid EU market integration and debates the merits of regulation dealing with financial innovation in the context of building a capital markets union in EU-27.

scholarly journals Russia’s Foreign Policy Evolution in the New Balkan Landscape

2020 ◽  
Vol 56 (3-4) ◽  
pp. 179-199
Author(s):  
Ekaterina Entina ◽  
Alexander Pivovarenko
Keyword(s):  
Foreign Policy ◽  
Soviet Union ◽  
Regional Security ◽  
Southeast Europe ◽  
The Balkans ◽  
Current Trends ◽  
The Soviet Union ◽  
Recent Developments ◽  
The Difference

The article reflects on the issue of the foreign policy strategy of modern Russia in the Balkans region. One of the most significant aspects of this problem is the difference in views between Russia and the West. Authors show how different interpretations of the events in former Yugoslavia in the 1990s and the beginning of the 2000s predetermined the sense of mutual suspicion and mistrust which spread to other regions such as the post-Soviet space. Exploring differences between the Russian and the Western (Euro-Atlantic) views on the current matters, authors draw attention to fundamental differences in terminology: while the Western narrative promotes more narrow geographical and political definitions (such as the Western Balkan Six), traditional Russian experts are more inclined to wider or integral definitions such as “the Balkans” and “Central and Southeast Europe”. Meanwhile none of these terms are applicable for analysis of the current trends such as the growing transit role of the Balkans region and its embedding in the European regional security architecture. Therefore, a new definition is needed to overcome the differences in vision and better understand significant recent developments in the region. Conceptualizing major foreign policy events in Central and Southeast Europe during the last three decades (the 1990s, 2000s and 2010s), authors demonstrate the significance of differences in tools and methods between the Soviet Union and the modern Russia. Permanent need for adaptation to changing political and security context led to inconsistence in Russian Balkan policy in the 1990s. Nevertheless, Russia was able to preserve an integral vision of the region and even to elaborate new transregional constructive projects, which in right political circumstances may promote stability and become beneficial for both Russia and the Euro-Atlantic community.

scholarly journals Cavitation Bubble Cloud Break-Off Mechanisms at Micro-Channels

Fluids ◽  
2021 ◽  
Vol 6 (6) ◽  
pp. 215
Author(s):  
Paul McGinn ◽  
Daniel Pearce ◽  
Yannis Hardalupas ◽  
Alex Taylor ◽  
Konstantina Vogiatzaki
Keyword(s):  
Cavitation Bubble ◽  
Cavitation Inception ◽  
Wave Dynamics ◽  
Bubble Cloud ◽  
Cloud Dynamics ◽  
Micro Channels ◽  
Physical Insight ◽  
Cloud Process ◽  
Good Agreement

This paper provides new physical insight into the coupling between flow dynamics and cavitation bubble cloud behaviour at conditions relevant to both cavitation inception and the more complex phenomenon of flow “choking” using a multiphase compressible framework. Understanding the cavitation bubble cloud process and the parameters that determine its break-off frequency is important for control of phenomena such as structure vibration and erosion. Initially, the role of the pressure waves in the flow development is investigated. We highlight the differences between “physical” and “artificial” numerical waves by comparing cases with different boundary and differencing schemes. We analyse in detail the prediction of the coupling of flow and cavitation dynamics in a micro-channel 20 m high containing Diesel at pressure differences 7 MPa and 8.5 MPa, corresponding to cavitation inception and "choking" conditions respectively. The results have a very good agreement with experimental data and demonstrate that pressure wave dynamics, rather than the “re-entrant jet dynamics” suggested by previous studies, determine the characteristics of the bubble cloud dynamics under “choking” conditions.

scholarly journals Theoretical Insight into the Reversal of Chemoselectivity in Diels-Alder Reactions of α,β-Unsaturated Aldehydes and Ketones Catalyzed by Brønsted and Lewis Acids

Organics ◽  
2021 ◽  
Vol 2 (1) ◽  
pp. 38-49
Author(s):  
Lakhdar Benhamed ◽  
Sidi Mohamed Mekelleche ◽  
Wafaa Benchouk
Keyword(s):  
Lewis Acids ◽  
Major Product ◽  
Diels Alder ◽  
Unsaturated Ketone ◽  
Unsaturated Aldehydes ◽  
Aldehydes And Ketones ◽  
Theoretical Insight ◽  
Insight Into ◽  
Good Agreement

Experimentally, a reversal of chemoselectivity has been observed in catalyzed Diels–Alder reactions of α,β-unsaturated aldehydes (e.g., (2E)-but-2-enal) and ketones (e.g., 2-hexen-4-one) with cyclopentadiene. Indeed, using the triflimidic Brønsted acid Tf2NH as catalyst, the reaction gave a Diels–Alder adduct derived from α,β-unsaturated ketone as a major product. On the other hand, the use of tris(pentafluorophenyl)borane B(C6F5)3 bulky Lewis acid as catalyst gave mainly the cycloadduct of α,β-unsaturated aldehyde as a major product. Our aim in the present work is to put in evidence the role of the catalyst in the reversal of the chemoselectivity of the catalyzed Diels–Alder reactions of (2E)-but-2-enal and 2-Hexen-4-one with cyclopentadiene. The calculations were performed at the ωB97XD/6-311G(d,p) level of theory and the solvent effects of dichloromethane were taken into account using the PCM solvation model. The obtained results are in good agreement with experimental outcomes.

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