scholarly journals Exploring the jamming transition over a wide range of critical densities

2017 ◽  
Vol 3 (4) ◽  
Author(s):  
Misaki Ozawa ◽  
Ludovic Berthier ◽  
Daniele Coslovich
Keyword(s):  
Large Scale ◽  
Volume Fraction ◽  
Pair Correlation ◽  
Orientational Order ◽  
Finite Size ◽  
Important Change ◽  
Three Dimensions ◽  
Length Scales ◽  
Jamming Transition ◽  
Wide Range

We numerically study the jamming transition of frictionless polydisperse spheres in three dimensions. We use an efficient thermalisation algorithm for the equilibrium hard sphere fluid and generate amorphous jammed packings over a range of critical jamming densities that is about three times broader than in previous studies. This allows us to reexamine a wide range of structural properties characterizing the jamming transition. Both isostaticity and the critical behavior of the pair correlation function hold over the entire range of jamming densities. At intermediate length scales, we find a weak, smooth increase of bond orientational order. By contrast, distorted icosahedral structures grow rapidly with increasing the volume fraction in both fluid and jammed states. Surprisingly, at large scale we observe that denser jammed states show stronger deviations from hyperuniformity, suggesting that the enhanced amorphous ordering inherited from the equilibrium fluid competes with, rather than enhances, hyperuniformity. Finally, finite size fluctuations of the critical jamming density are considerably suppressed in the denser jammed states, indicating an important change in the topography of the potential energy landscape. By considerably stretching the amplitude of the critical “J-line”, our work disentangles physical properties at the contact scale that are associated with jamming criticality, from those occurring at larger length scales, which have a different nature.

Nanoemulsions: A Versatile Technology for Oil and Gas Applications

2021 ◽  
Author(s):  
Nouf AlJabri ◽  
Nan Shi
Keyword(s):  
Droplet Size ◽  
Large Scale ◽  
Oil And Gas ◽  
Volume Fraction ◽  
Oil Industry ◽  
Oil And Gas Industry ◽  
High Energy ◽  
Small Droplet ◽  
Gas Industry ◽  
Wide Range

Abstract Nanoemulsions (NEs) are kinetically stable emulsions with droplet size on the order of 100 nm. Many unique properties of NEs, such as stability and rheology, have attracted considerable attention in the oil industry. Here, we review applications and studies of NEs for major upstream operations, highlighting useful properties of NEs, synthesis to render these properties, and techniques to characterize them. We identify specific challenges associated with large-scale applications of NEs and directions for future studies. We first summarize useful and unique properties of NEs, mostly arising from the small droplet size. Then, we compare different methods to prepare NEs based on the magnitude of input energy, i.e., low-energy and high-energy methods. In addition, we review techniques to characterize properties of NEs, such as droplet size, volume fraction of the dispersed phase, and viscosity. Furthermore, we discuss specific applications of NEs in four areas of upstream operations, i.e., enhanced oil recovery, drilling/completion, flow assurance, and stimulation. Finally, we identify challenges to economically tailor NEs with desired properties for large-scale upstream applications and propose possible solutions to some of these challenges. NEs are kinetically stable due to their small droplet size (submicron to 100 nm). Within this size range, the rate of major destabilizing mechanisms, such as coalescence, flocculation, and Ostwald ripening, is considerably slowed down. In addition, small droplet size yields large surface-to-volume ratio, optical transparency, high diffusivity, and controllable rheology. Similar to applications in other fields (food industry, pharmaceuticals, cosmetics, etc.), the oil and gas industry can also benefit from these useful properties of NEs. Proposed functions of NEs include delivering chemicals, conditioning wellbore/reservoir conditions, and improve chemical compatibility. Therefore, we envision NEs as a versatile technology that can be applied in a variety of upstream operations. Upstream operations often target a wide range of physical and chemical conditions and are operated at different time scales. More importantly, these operations typically consume a large amount of materials. These facts not only suggest efforts to rationally engineer properties of NEs in upstream applications, but also manifest the importance to economically optimize such efforts for large-scale operations. We summarize studies and applications of NEs in upstream operations in the oil and gas industry. We review useful properties of NEs that benefit upstream applications as well as techniques to synthesize and characterize NEs. More importantly, we identify challenges and opportunities in engineering NEs for large-scale operations in different upstream applications. This work not only focuses on scientific aspects of synthesizing NEs with desired properties but also emphasizes engineering and economic consideration that is important in the oil industry.

scholarly journals The cardiac nanoenvironment: form and function at the nanoscale

2021 ◽  
Author(s):  
Jashan P. Singh ◽  
Jennifer L. Young
Keyword(s):  
Large Scale ◽  
New Materials ◽  
Length Scales ◽  
Form And Function ◽  
Molecular Features ◽  
Wide Range ◽  
Physiological Homeostasis ◽  
Organ Level ◽  
And Function

AbstractMechanical forces in the cardiovascular system occur over a wide range of length scales. At the whole organ level, large scale forces drive the beating heart as a synergistic unit. On the microscale, individual cells and their surrounding extracellular matrix (ECM) exhibit dynamic reciprocity, with mechanical feedback moving bidirectionally. Finally, in the nanometer regime, molecular features of cells and the ECM show remarkable sensitivity to mechanical cues. While small, these nanoscale properties are in many cases directly responsible for the mechanosensitive signaling processes that elicit cellular outcomes. Given the inherent challenges in observing, quantifying, and reconstituting this nanoscale environment, it is not surprising that this landscape has been understudied compared to larger length scales. Here, we aim to shine light upon the cardiac nanoenvironment, which plays a crucial role in maintaining physiological homeostasis while also underlying pathological processes. Thus, we will highlight strategies aimed at (1) elucidating the nanoscale components of the cardiac matrix, and (2) designing new materials and biosystems capable of mimicking these features in vitro.

Effect of interphase zone on the overall elastic properties of nanoparticle-reinforced polymer nanocomposites

2018 ◽  
Vol 53 (9) ◽  
pp. 1261-1274 ◽  
Author(s):  
Jafar Amraei ◽  
Jafar E Jam ◽  
Behrouz Arab ◽  
Roohollah D Firouz-Abadi
Keyword(s):  
Mechanical Properties ◽  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Polymer Nanocomposites ◽  
Volume Fraction ◽  
Finite Size ◽  
Radial Distance ◽  
Shear Moduli ◽  
Wide Range ◽  
Dynamics Simulations

In the current work, the effect of interphase region on the mechanical properties of polymer nanocomposites reinforced with nanoparticles is studied. For this purpose, a closed-form interphase model as a function of radial distance based on finite-size representative volume element is suggested to estimate the mechanical properties of particle-reinforced nanocomposites. The effective Young’s and shear moduli of thermoplastic polycarbonate-based nanocomposites for a wide range of sizes and volume fractions of silicon carbide nanoparticles are investigated using the proposed interphase model and molecular dynamics simulations. In order to investigate the effect of particle size, several unit cells of the same volume fraction, but with different particle radii have been considered. The micromechanics-based homogenization results are in good agreement with the results of molecular dynamics simulations for all models. This study demonstrates that the suggested micromechanical interphase model has the capacity to estimate effective mechanical properties of polymer-based nanocomposites reinforced with spherical inclusions.

COMPUTER SIMULATION OF PROFILES OF INTERFACES BETWEEN COEXISTING PHASES: DO WE UNDERSTAND THEIR FINITE SIZE EFFECTS?

2000 ◽  
Vol 11 (06) ◽  
pp. 1093-1113 ◽  
Author(s):  
KURT BINDER ◽  
MARCUS MÜLLER
Keyword(s):  
Finite Size ◽  
Three Dimensions ◽  
Polymer Mixtures ◽  
Binary Polymer ◽  
Linear Dimensions ◽  
Small Correction ◽  
Wide Range ◽  
Coexisting Phases ◽  
Actual Profile ◽  
Widespread Belief

Interfaces between coexisting phases are very common in condensed matter physics, and thus many simulations attempt to characterize their properties, in particular, the interfacial tension and the interfacial profile. However, while theory usually deals with the "intrinsic profile", the latter is not a straightforward output of a simulation: The actual profile (observed in simulations and/or experiments!) is broadened by lateral fluctuations. Therefore, in the usual simulation geometry of L × L × L (in three dimensions), where one chooses suitable boundary conditions to stabilize one or two interfaces of (minimal) area L × L, the profile (and in particular the interfacial width) depends on both linear dimensions L and D (parallel and perpendicular to the interface). Choosing recent simulations of interfaces between coexisting phases of unmixed binary polymer mixtures as an example, we show that this interfacial broadening is not a small correction, but has pronounced effects; for a reliable data analysis, it is (unfortunately!) necessary to vary L and D over a wide range. We present counterexamples to the widespread belief that for small linear dimensions, the intrinsic profile is straightforwardly recovered and speculate about conditions where this belief may be valid.

Characterization of combustion in a gas engine ignited using a small un-scavenged pre-chamber

2018 ◽  
Vol 21 (7) ◽  
pp. 1085-1106 ◽  
Author(s):  
Guoqing Xu ◽  
Yuri Martin Wright ◽  
Michele Schiliro ◽  
Konstantinos Boulouchos
Keyword(s):  
Large Scale ◽  
Combustion Engine ◽  
Turbulent Flame ◽  
Combustion Model ◽  
Medium Size ◽  
Main Chamber ◽  
Length Scales ◽  
Gas Engine ◽  
Turbulent Flame Speed ◽  
Wide Range

Prechamber ignition technology receives increasing attention due to its considerable improvement on engine combustion efficiency and stability. However, fundamental knowledge concerning flame propagation inside the pre-chamber and jet formation in the main chamber is still quite scarce. In this study, a small (<0.5% VTDC) un-scavenged pre-chamber was tested in a medium size gas engine with pressure transducers installed in both pre- and main chamber. Three-dimensional computational reactive fluid dynamics Reynolds-averaged Navier–Stokes simulations were carried out using a level-set combustion model –G-equation – towards improved understanding of the combustion processes occurring inside the pre and main chamber. The characteristics of the turbulence and the flame at locations just ahead of the propagating turbulent flame front were recorded and analysed by means of the well-known Borghi–Peters diagram. The results revealed that the characteristics of the flame inside the pre-chamber differed greatly from those inside the main chamber due to considerably reduced turbulent length scales. In addition, a wide range of turbulence intensity and length scales are covered throughout the combustion event, presenting a significant challenge to modelling of flame–turbulence interaction. Various turbulent flame speed ( ST) closures widely used in internal combustion engine simulation were therefore assessed and the ranges of their respective model constants explored. A correlation for ST is subsequently proposed by blending two formulations of Gülder developed for small and large scale turbulence, respectively, and compared to the well-known Peters correlation. With appropriate model constants, both successfully reproduce the pre and main chamber combustion for the reference case in terms of evolutions of cylinder pressure, heat release rate and pressure difference between pre and main chamber. Following successful calibration of the reference operating condition, variations in engine speed, load, spark timing and lambda were calculated using both correlations, demonstrating encouraging predictive capabilities of the proposed modelling strategy.

Effect of Nanoscale rods on the Kinetics of Phase-Separating Multi-Component Fluids

2004 ◽  
Vol 856 ◽  
Author(s):  
Michael J.A. Hore ◽  
Mohamed Laradji
Keyword(s):  
Phase Separation ◽  
Large Scale ◽  
Volume Fraction ◽  
Three Dimensions ◽  
Domain Growth ◽  
Slowing Down ◽  
Nanoparticles Volume Fraction ◽  
Scale Particle ◽  
Dynamics Simulations ◽  
Kinetics Of

ABSTRACTUsing large scale particle dynamics simulations, we investigated the effect of nanoscale rods on the dynamics of phase separation dynamics of two-component fluids in three dimensions. We found that when the nanoparticles interact more attractively with one of the two segregating component, they lead to a reduction of the rate of domain growth, and that this decrease is intensified as the nanoparticles volume fraction is increased. Furthermore, our results show that nanorods are much more effective in slowing down the kinetics than nanosphres. The dramatic effect of nanorods on the dynamics of phase separation of multi-component fluids, as opposed to nanospheres, implies that they may be used as an efficacious emulsifying agent of multi-component polymer blends.

scholarly journals Dense granular flow rheology in turbulent bedload transport

2016 ◽  
Vol 804 ◽  
pp. 490-512 ◽  
Author(s):  
Raphael Maurin ◽  
Julien Chauchat ◽  
Philippe Frey
Keyword(s):  
Granular Flow ◽  
Large Scale ◽  
Volume Fraction ◽  
Solid Volume Fraction ◽  
Particle Diameter ◽  
Bedload Transport ◽  
Spherical Particles ◽  
Granular Rheology ◽  
Wide Range ◽  
Dense Granular Flow

The local granular rheology is investigated numerically in turbulent bedload transport. Considering spherical particles, steady uniform configurations are simulated using a coupled fluid–discrete-element model. The stress tensor is computed as a function of the depth for a series of simulations varying the Shields number, the specific density and the particle diameter. The results are analysed in the framework of the $\unicode[STIX]{x1D707}(I)$ rheology and exhibit a collapse of both the shear to normal stress ratio and the solid volume fraction over a wide range of inertial numbers. Contrary to expectations, the effect of the interstitial fluid on the granular rheology is shown to be negligible, supporting recent work suggesting the absence of a clear transition between the free-fall and turbulent regimes. In addition, data collapse is observed up to unexpectedly high inertial numbers $I\sim 2$, challenging the existing conceptions and parametrisation of the $\unicode[STIX]{x1D707}(I)$ rheology. Focusing upon bedload transport modelling, the results are pragmatically analysed in the $\unicode[STIX]{x1D707}(I)$ framework in order to propose a granular rheology for bedload transport. The proposed rheology is tested using a 1D volume-averaged two-phase continuous model, and is shown to accurately reproduce the dense granular flow profiles and the sediment transport rate over a wide range of Shields numbers. The present contribution represents a step in the upscaling process from particle-scale simulations towards large-scale applications involving complex flow geometry.

Electron microscopy study of reactively sputter-deposited Ti/N films on silicon

1992 ◽  
Vol 50 (2) ◽  
pp. 1362-1363
Author(s):  
V. C. Kannan ◽  
A. K. Singh ◽  
R. B. Irwin ◽  
S. Chittipeddi ◽  
F. D. Nkansah ◽  
...  
Keyword(s):  
Integrated Circuits ◽  
Large Scale ◽  
Hexagonal Phase ◽  
Microscopy Study ◽  
Electron Microscopy Study ◽  
Process Conditions ◽  
Tin Films ◽  
Wide Range ◽  
Fcc Phase ◽  
Circuits Vlsi

Titanium nitride (TiN) films have historically been used as diffusion barrier between silicon and aluminum, as an adhesion layer for tungsten deposition and as an interconnect material etc. Recently, the role of TiN films as contact barriers in very large scale silicon integrated circuits (VLSI) has been extensively studied. TiN films have resistivities on the order of 20μ Ω-cm which is much lower than that of titanium (nearly 66μ Ω-cm). Deposited TiN films show resistivities which vary from 20 to 100μ Ω-cm depending upon the type of deposition and process conditions. TiNx is known to have a NaCl type crystal structure for a wide range of compositions. Change in color from metallic luster to gold reflects the stabilization of the TiNx (FCC) phase over the close packed Ti(N) hexagonal phase. It was found that TiN (1:1) ideal composition with the FCC (NaCl-type) structure gives the best electrical property.

New Models of Content Creation and Scholarship at the Intersection of Library Spaces, Technologies, and Expertise

2018 ◽  
Author(s):  
Mike Nutt ◽  
Gregory Raschke
Keyword(s):  
Large Scale ◽  
Interactive Media ◽  
Scholarly Communication ◽  
Three Dimensions ◽  
Organizational Capabilities ◽  
High Definition ◽  
Content Creation ◽  
Full Life Cycle ◽  
Digital Scholarship ◽  
Digital Objects

Library spaces that blend collaboration areas, advanced technologies, and librarian expertise are creating new modes of scholarly communication. These spaces enable scholarship created within high-definition, large-scale visual collaborative environments. This emergent model of scholarly communication can be experienced within those specific contexts or through digital surrogates on the networked Web. From experiencing in three dimensions the sermons of John Donne in 1622 to interactive media interpretations of American wars, scholars are partnering with libraries to create immersive digital scholarship. Viewing the library as a research platform for these emergent forms of digital scholarship presents several opportunities and challenges. Opportunities include re-engaging faculty in the use of library space, integrating the full life-cycle of the research enterprise, and engaging broad communities in the changing nature of digitally-driven scholarship. Issues such as identifying and filtering collaborations, strategically managing staff resources, creating surrogates of immersive digital scholarship, and preserving this content for the future present an array of challenges for libraries that require coordination across organizations. From engaging and using high-technology spaces to documenting the data and digital objects created, this developing scholarly communication medium brings to bear the multifaceted skills and organizational capabilities of libraries.

THE SOME QUESTIONS OF AUTONOMOUS MOTION AND MANAGEMENT OF LAND-MOBILE ROBOTIC COMPLEXES FOR UKRAINIAN GROUND FORCESE

2019 ◽  
pp. 53-58
Author(s):  
О. Кravchuk ◽  
V. Symonenkov ◽  
I. Symonenkova ◽  
O. Hryhorev
Keyword(s):  
Large Scale ◽  
Armed Forces ◽  
Distributed Information ◽  
Wide Range ◽  
Highly Effective ◽  
Information Management Systems ◽  
Robotic Devices ◽  
Principles And Standards ◽  
And Control ◽  
The Eu

Today, more than forty countries of the world are engaged in the development of military-purpose robots. A number of unique mobile robots with a wide range of capabilities are already being used by combat and intelligence units of the Armed forces of the developed world countries to conduct battlefield intelligence and support tactical groups. At present, the issue of using the latest information technology in the field of military robotics is thoroughly investigated, and the creation of highly effective information management systems in the land-mobile robotic complexes has acquired a new phase associated with the use of distributed information and sensory systems and consists in the transition from application of separate sensors and devices to the construction of modular information subsystems, which provide the availability of various data sources and complex methods of information processing. The purpose of the article is to investigate the ways to increase the autonomy of the land-mobile robotic complexes using in a non-deterministic conditions of modern combat. Relevance of researches is connected with the necessity of creation of highly effective information and control systems in the perspective robotic means for the needs of Land Forces of Ukraine. The development of the Armed Forces of Ukraine management system based on the criteria adopted by the EU and NATO member states is one of the main directions of increasing the effectiveness of the use of forces (forces), which involves achieving the principles and standards necessary for Ukraine to become a member of the EU and NATO. The inherent features of achieving these criteria will be the transition to a reduction of tasks of the combined-arms units and the large-scale use of high-precision weapons and land remote-controlled robotic devices. According to the views of the leading specialists in the field of robotics, the automation of information subsystems and components of the land-mobile robotic complexes can increase safety, reliability, error-tolerance and the effectiveness of the use of robotic means by standardizing the necessary actions with minimal human intervention, that is, a significant increase in the autonomy of the land-mobile robotic complexes for the needs of Land Forces of Ukraine.

Sign in / Sign up

Export Citation Format

Share Document