scholarly journals The dynamic evolution of compaction bands in highly porous carbonates: the role of local heterogeneity for nucleation and propagation

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Xiao Chen ◽  
Hamid Roshan ◽  
Adelina Lv ◽  
Manman Hu ◽  
Klaus Regenauer-Lieb
Keyword(s):  
Dynamic Evolution ◽  
Compaction Bands ◽  
Local Heterogeneity ◽  
Highly Porous

Study of the Water-Glass Role in the Foam Glass Synthesis Using Glycerol Foaming Agent

2021 ◽  
Vol 316 ◽  
pp. 153-158
Author(s):  
Boris M. Goltsman ◽  
Lyubov A. Yatsenko ◽  
Natalia S. Goltsman
Keyword(s):  
Porous Structure ◽  
Structure Formation ◽  
Water Glass ◽  
Glass Batch ◽  
Foam Glass ◽  
Foaming Agent ◽  
Additive Type ◽  
Highly Porous ◽  
Material Porosity

The article discusses the peculiarities of the "water-glass – glycerol" foaming mixture components interaction during foam glass synthesis. The important role of the foaming additive type in the foam glass porous structure formation was described, the main foaming substances were listed. The obtaining and researching technology of the samples was described, the compositions of the initial batches using the "water-glass – glycerol" mixture were developed. It was shown that a material with a highly porous structure and density below 500 kg/m3 can be obtained only with the combined introduction of water-glass and glycerol. In this case, mixtures with a predominance of water-glass in the foaming mixture possess optimal properties. Using DSC, it was shown that the addition of water-glass to the mixture completely eliminates the evaporation of glycerol at lower temperatures and intensifies its combustion at higher temperatures. Thus, the addition of water-glass to the glycerol-based foam glass batch allows glycerol to be saved up to higher temperatures that increases the resulting material porosity.

scholarly journals The Role of the UN Security Council in COVID-19 Crisis Management

2020 ◽  
pp. 105-122
Author(s):  
Svetlana Cebotari ◽  
Selena Stejaru
Keyword(s):  
International Relations ◽  
Crisis Management ◽  
Interpersonal Relations ◽  
International System ◽  
Dynamic Evolution ◽  
Un Security Council ◽  
Peace And Security ◽  
The Impact ◽  
Over Time

Currently, we experience a conditional reality imposed by the COVID19 pandemic, with both immediate and long-lasting repercussions on the international system and the behavior of each state. For this reason and because the new virus has a dynamic evolution in time and space, research of the impact of the new virus is needed not only from a biogenetic perspective but also in the context of other fields, including the international relations realm. The events we are witnessing at the present challenge to keep up with transformations taking place in the international arena, especially those in the field of virology. As epidemics over time, viruses that cause them to change and occur constantly remain only the fact that they will always influence not only interpersonal relations but impose conditions for new realities in the system of international relations. This article aims to highlight the main gaps in the work of the institution responsible for maintaining peace and security in the international arena, especially in the context of the COVID-19 crisis.

Control of Failure Evolution in 3D Cellular Woven Composite Systems

2000 ◽  
Author(s):  
Jared N. Baucom ◽  
Mohammed A. Zikry ◽  
Yiping Qiu
Keyword(s):  
Areal Density ◽  
Textile Composites ◽  
Woven Composite ◽  
Ballistic Performance ◽  
Composite Systems ◽  
Matrix Cracks ◽  
Failure Evolution ◽  
Undesirable Property ◽  
Highly Porous

Abstract This investigation examines the role of porosity in the perforation resistance of 3-D woven fiber reinforced epoxy panels under impact by rigid projectiles at velocities of 100 to 200 m/s. Incident and residual velocities are measured to determine the energy absorption by the target. To compare samples of different areal density, the energy is normalized by the target areal density. The sample responses segregate by porosity, and the more highly porous samples absorb a greater amount of specific energy. The reason for this is unclear but may be due to the deflection of matrix cracks by pores or due to the greater flexibility of the fibers to absorb energy through tensile straining. Although porosity is generally an undesirable property in textile composites, the induction of porosity may result in reduced panel weight without degradation of ballistic performance, a clear advantage for weight minimization.

Detection and enumeration of microbial cells within highly porous calcareous reef sands

2006 ◽  
Vol 57 (4) ◽  
pp. 415 ◽  
Author(s):  
Christian Wild ◽  
Christian Laforsch ◽  
Markus Huettel
Keyword(s):  
Laser Scanning ◽  
Complex Surface ◽  
Porous Matrix ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Size Spectrum ◽  
Order Of Magnitude ◽  
Grain Surface ◽  
Highly Porous

In order to assess and to compare the abundances of prokaryotes in coral sands from three different areas in the Indo-Pacific, a technique was developed and evaluated for enumeration of prokaryotes living on and within calcareous grains. Propidium iodide labelling of prokaryotes and consecutive confocal laser scanning microscopy showed microbial colonisation within pores and small fissures of the coral sands. This embedded microbial colonisation required at least four extractions with weak acetic acid to dissolve the grain surface layer in order to detach 97% of the prokaryotic cells. Microbial enumeration based on this technique revealed that the abundance of prokaryotes in the carbonate sands were not significantly different among the three sites, but were about one order of magnitude higher than reported for silicate sands of a similar grain size spectrum. A possible reason for this high abundance of prokaryotes is the complex surface structure of the biogenic calcareous grains, their correspondingly highly porous matrix and the associated ability of prokaryotes to penetrate into carbonate grains. Our results highlight the role of calcareous reef sands as a substratum with a large specific surface area for prokaryotic colonisation and emphasise the contribution of calcium carbonate reef sands for element cycles in subtropical and tropical ecosystems.

Organizational and Temporal Shifts in Procurement Analytics: Implications for Research

2020 ◽  
Author(s):  
Robert B. Handfield ◽  
Seongkyoon Jeong
Keyword(s):  
Data Analytics ◽  
Temporal Evolution ◽  
Academic Research ◽  
Leadership Role ◽  
First Century ◽  
Dynamic Evolution ◽  
Digital Environment ◽  
Early Twenty ◽  
Temporal Shifts

Academic research in the early twenty-first century highlights the emerging role of analytics in all functions, including procurement and supply chain. Given the rapid shifts in technology that are under way in this field, academic research may struggle to keep up with the dynamic evolution of procurement platforms. This chapter assesses the current set of procurement analytics–based research and observes the organizational and temporal evolution of how procurement analytics is proceeding. Next, the chapter reviews a number of procurement platforms and interviews with procurement executives to suggest that academic research is at the same nascent stage as the evolution of the technology, which is often highly touted but is in the early stages of development. The analysis also highlights the importance of data integrity and quality as major roadblocks preventing the adoption of advanced procurement analytics. However, the analysis suggests that technologies will continue to propel the expansion of organizational and temporal shifts in procurement analytics, enabled by the emerging digital environment and evolving technologies such as data analytics and cognitive analytics. As a result, we will likely continue to witness massive changes in the procurement analytics environment in the next three to five years. The chapter concludes that although the current maturity of procurement analytics is low, supply management should adopt a leadership role in advancing the procurement analytics scope and scale.

scholarly journals Review of studies on capture of comets by neptune and its role in the dynamic evolution of cometary orbits

1985 ◽  
Vol 83 ◽  
pp. 243-258
Author(s):  
E.I. Kazimirchack-Polonskaya
Keyword(s):  
Planetary System ◽  
Historical Review ◽  
Dynamic Evolution ◽  
Hyperbolic Orbit ◽  
Secular Evolution ◽  
Outer Planets ◽  
Period Orbit ◽  
Short Period ◽  
Being Moved

AbstractA historical review of investigations on encounters of minor bodies with outer planets is presented. The dominating role of Jupiter in the capture of comets and in determining their secular evolution is emphasized. Participation in the above process of Saturn, Uranus and, especially, Neptune is investigated. In the present paper are considered five fictitious comets, penetrating into the depths of Neptune’s sphere of action, where they undergo large orbital transformations and capture by Neptune. Two near-circular orbits are transformed into elliptical ones, their perihelia being moved inside the planetary system; one hyperbolic orbit is transformed into a transplutonian one, another into a typical short-period orbit of the Neptune’s family with a perihelion accessible to terrestrial observers. One fictitious comet is captured by Neptune as a stable satellite.

Kinematic Approach in the Impact Problem of Rigid Bodies

1989 ◽  
Vol 42 (11S) ◽  
pp. S233-S244 ◽  
Author(s):  
A. Sinopoli
Keyword(s):  
Degrees Of Freedom ◽  
Rigid Bodies ◽  
Dynamic Evolution ◽  
Rigid Block ◽  
Subsequent Motion ◽  
The Impact ◽  
Finite Extent ◽  
Kinematic Approach ◽  
Impact Problem

The aim of this work is to analyze, by means of a kinematic approach, the problem of the impact between rigid bodies, when the surfaces involved in the impulsive phenomenon are of finite extent. The formulation here adopted permits to use the Gauss variational principle of “least compulsion” and to formulate the dynamic evolution of the system, after an impact, as a minimization problem. In this case, among all the possible subsequent motions, the real one is that which minimizes the kinetic energy connected to the sudden velocities variations. Interesting results are obtained in the case of the impact between a rigid column (either monolithic or made of several blocks) and a rigid ground. In particular, it can be shown that if the previous motion of a rigid block is a rotation around its base corner edge, the motion after the impact is either a rototranslation or merely a translation, depending on the dimensional ratio. In any case, the subsequent motion is characterized by a component of sliding, so that the impact plays the role of filter between the possible degrees of freedom of the system and, at the same time, determines a possible coupling between rotation and translation. This conclusion is a novelty with respect to the results obtained in other papers [4–6], where a classical approach for the impact has been adopted.

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