Hybrid Flows Research Articles

Load-balanced Routing Heuristics for Bandwidth Allocation of AVB Flow in TSN

Time-Sensitive Networking (TSN) is a new technology developed from Ethernet that guarantees deterministic transmission of various types of flows, such as Time-triggered (TT) flows and Audio-video-bridging (AVB) flows, in the same network. Currently, Time-aware Shaping (TAS) and Credit-based Shaping (CBS) are widely used for scheduling hybrid flows, where the credit value in CBS is directly linked to the logical bandwidth value idleSlope , which affects the real-time performance of AVB flows. However, as the network scale increases, existing bandwidth allocation methods result in higher computation times and lower allocation success rates. In this paper, the aforementioned problem is addressed by two-step: first, we design a load-balanced routing heuristic (LBRH) to improve the allocation success rate; second, we accelerate the CBS bandwidth allocation by using unified bandwidth allocation scheme, which integrates LBRH and further improves the allocation success rate. Performance evaluation in multiple test cases shows that LBRH can improve the success rate of bandwidth allocation, and the unified bandwidth allocation scheme integrating LBRH significantly reduces the overall execution time while improving the success rate of bandwidth allocation, which is more suitable for large-scale TSN networks with complex routing.

Thermal performance appraisal of hybrid and nanofluid flow between a cone and a disk with variable thermal conductivity, viscous dissipation, and Joule heating

In many engineering systems, hybrid and nanofluids are influenced by their respective thermophysical characteristics. Lately, several models have been envisaged to foresee the hybrid and nanofluid attributes. The properties of hybrid nanofluids (HNFs) as potential heat transfer fluids are controlled by numerous aspects such as solid part size, volume fraction, and temperature. Considering the interesting facts of the hybrid and nanofluid flows, we in this exploration examined the thermal performance comparison of both types of fluid flows. The nanofluid and HNF are composed of molybdenum disulfide (MoS[Formula: see text]/kerosene oil and silicon dioxide–molybdenum disulfide (SiO2–MoS[Formula: see text]/kerosene oil, respectively. The flows are taken in a canonical gap between the cone and the disk. Both the cone and the disk may be rotating or stationary. The novelty of the computational model is enhanced by discussing the effects of viscous dissipation, Joule heating, and the variable thermal conductivity with convective condition. The Tawari and Das model is designed to analyze the heat transfer performance of the assumed fluid flows. The assumed fluid model is transmuted into the set of differential equations that are dealt numerically with the bvp4c MATLAB approach. The results are displayed in tables and graphical forms. For elevating estimations of the Eckert number, the heat transmission rate is found to be more significant in the disk than cone. It is also learned that hybrid nanoliquid heat transfer performance outperforms nanoliquid. The fluid velocity increases by raising the nanoparticle volume fraction [Formula: see text], and is decreasing for a higher magnetic field parameter. With the elevating estimates of thermal conductivity, it is shown that the cone transmits heat more quickly whereas the disc transmits heat more slowly. The thermal conductivity parameter increases the probability of collision of the liquid particles, that ultimately upsurges fluid heat transmission rate.

Hall current and ion slip effects on a ternary hybrid nanofluid flow over a bidirectional surface with chemical reaction and Cattaneo–Christov heat flux

The interaction between fluid flow and magnetic fields finds real-life applications in various industries, including semiconductors, fusion energy, plasma processing, and spacecraft propulsion. In this study, our objective is to investigate the behavior of a ternary hybrid nanofluid as it flows over a surface stretched in two directions. We consider the amalgamation of Hall current and ion slip effects, as well as homogeneous–heterogeneous reactions. The flow is influenced by Cattaneo–Christov heat flux, heat generation/absorption, and slip and convective conditions at the surface boundary. This ternary hybrid nanofluid comprises three types of nanoparticles—silicon carbide (SiC), copper oxide (CuO), and titanium oxide (TiO2)—suspended in a base fluid of diathermic oil (DO). We employ numerical methods to solve this system, utilizing the bvp4c function in MATLAB software. The results are presented graphically, demonstrating the correlation between key parameters and associated profiles. The findings reveal that the thermal profile diminishes with increasing Biot number but improves with the thermal relaxation effect. Furthermore, it is examined that the performance of the ternary hybrid nanofluid flow surpasses that of both hybrid and simple nanofluid flows. To corroborate our model, we provide a comparison with a published work in a limiting case within this study.

A comparative assessment of mono and hybrid magneto nanofluid flow over a stretching cylinder in a permeable medium with generalized Fourier’s law

This study investigates the flow and heat transfer of mono and hybrid nanofluids owing to a stretching cylinder in a porous medium under the influence of a magnetic field and convective boundary condition. The hybrid nanofluid is made up of copper (Cu) and silver (Ag) nanoparticles dispersed in a water-ethylene glycol mixture at a mass ratio of 50:50. The binary mixture of water and ethylene glycol is intermixed with spherical-shaped nanoparticles (copper) to create a mono nanofluid. The study considers the effects of generalized Fourier’s law and heat generation/absorption. The novelty of the study lies in considering the comparison of hybrid and mono nanofluid flows heat transfer efficiency with assumed effects and convective condition at the boundary of the cylinder. A system of ordinary differential equations (ODEs) controlling the flow and heat transport are derived using similarity transformations and are solved numerically using the bvp4c program of MATLAB software. The work explores the ways in which different parameters, such as the shape of the nanoparticles and their volume percentage, affect the pertinent profiles and are depicted in the form of graphical illustrations and numerically tabulated values. The results demonstrate that, in comparison to mono nanofluids, hybrid nanofluids including spherical and blade nanoparticles have a higher heat transfer rate and reduced surface drag when the particle volume fraction is increased in a water-ethylene glycol combination. Furthermore, there is a 0.83% increase in the heat transfer rate for hybrid nanofluids in comparison to mono nanofluids. This is because compared to mono nanofluids, hybrid nanofluids have lower viscosity and better heat conductivity. The results obtained in this study are vetted by making a comparison with published works and an excellent agreement between the values is seen. The study may find use in solar thermal systems, electronic cooling, heat exchangers, and other areas.

Flow transformations, mud partitioning and the variable stratigraphic architecture of basin-floor fan fringes

Highly efficient sediment gravity flows can bypass mid fan channels and lobes and deposit significant volumes of sand, mud and particulate organic matter in outer fan and basin plain settings. The Serpukhovian to Bashkirian fill to the Shannon Basin, western Ireland, includes deep-water fan deposits (Ross Sandstone Fm) that gradationally overlie basin floor shales (Clare Shale Fm). As part of a broader progradational succession, the upward transition from muddy basin floor to sandy fan preserves the stacked deposits of settings present prior to and outboard of mid-fan channels and lobes. Three fully cored boreholes and associated wireline data constrain the facies tracts in an 18 km long panel orientated oblique to original depositional dip. Two distal successions dominated by hybrid event beds (HEBs) are recognised, separated by a prominent condensed section. The lower Cosheen system includes m-thick, tabular HEBs with prominent linked debrites that pass down dip into much thinner sandstones overlain by sand-speckled mudstone caps that thicken distally before thinning. The latter are interpreted as secondary mudflows released following reconstitution of more thoroughly mixed sections of the up-dip linked debrites. Significant bypass and accumulation of mud by this mechanism helped heal local topography and maintain a relatively flat sea floor promoting an overall tabular geometry for the deposits of larger volume hybrid flows reaching the distal sector of the basin. The overlying distal Ross system fringe is characterised by very fine to fine-grained sandstones and is lateral to compensationally-stacked lobes further to the west. It has a progradational (at least initially) stacking pattern, facies transitions developed over shorter length scales, and includes outsized event beds but these are thinner than those in the Cosheen system. Common banding and evidence for turbulence suppression by dispersed clay rather than entrained mud clasts indicate these were transitional flows. In this case, event beds are inferred to taper distally, with significant mud emplaced by plug flow retained as caps to sandy event beds rather than bypassing down-dip. Different flow transformation mechanisms thus impacted how mud was partitioned across the fringe of the two systems and this influenced bed geometries, larger scale bed stacking patterns and stratigraphy. Whereas the flow efficiency concept stresses the ability of flows to carry sand in a basinward direction, it is also imperative to consider the variable efficiency of mud transport given the operation of clay-induced flow transformations. These can either promote bypass or trigger premature fallout of mud with implications for how systems fill accommodation, bed -scale facies transitions and the burial and preservation of particulate organic carbon fractionated along with the clay in deep-water system fringes.

The Discontinuous Galerkin Method and its Implementation in the RAMEG3D Software Package

Currently, the Discontinuous Galerkin Method (DGM) is widely used to solve complex multi-scale problems of mathematical physics that have important applied significance. When implementing it, the question of choosing a discrete approximation of flows for viscous terms of the Navier-Stokes equation is important.It is necessary to focus on the construction of limiting functions, on the selection of the best discrete approximations of diffusion flows, and on the use of implicit and iterative methods for solving the obtained differential-difference equations for the successful application of DGM on three-dimensional unstructured grids.First-order numerical schemes and second-order DGM schemes with Godunov, HLLC, Rusanov-Lax-Friedrichs numerical flows and hybrid flows are investigated. For high-order precision methods, it is necessary to use high-order time schemes.The Runge-Kutta scheme of the third order is used in the work. The equations are written as a system of first-order equations, when solving the Navier-Stokes equation by the discontinuous Galerkin method.

Dynamics of heat passage in hybrid and tri-hybrid Oldroyd-B blood flows through a wedge-shaped artery: A medical application

This article investigates the heat transmission rate in hybrid and tri-hybrid particles that emerged in Oldroyed-B blood flow flowing through wedge shape arteries. The rate type Oldroyd-B flow model is considered to examine the behavior of relaxation and retardation times. The transmuted nondimensional conditions and boundary restrictions are solved using the bvp5c technique. It is observed that the heat transmission rate is high for the tri-hybrid (GO-Al2O3-TiO2) blood flow combination compared to the hybrid (Al2O3-TiO2) blood combination. This study can deliver a vibrant opinion concerning heat transmission behavior and the blood flow nature in a wedge shape artery.

Impact of surface catalyst and variable diffusion coefficients on a comparative appraisal of hybrid and nanofluid flows

A comparison of the hybrid and nanofluid flows performance amidst two spinning disks accompanying variable thermal conductivity and viscosity is appraised in this study. The hybrid nanofluid is comprised of single-wall-multiwall carbon nanotubes/water combination and a simple nanofluid consists of single-wall carbon nanotubes (multiwall carbon nanotubes)/water amalgamation. The selection of carbon nanotubes is based on their matchless characteristics including lightweight, extraordinary thermal conductivity attributes, and stability. The envisaged model is supported with catalysis on the surface to influence the homogeneous-heterogeneous reactions and trigger the process in a relatively lesser time. The cases of clockwise and anticlockwise rotation for both disks are undertaken. The numerical MATLAB-based bvp4c technique is betrothed. The graphical illustrations depicting the association of the prominent parameters with the allied profiles are given with logical arguments. The fallouts revealed that the hybrid nanofluids are more effective than the simple nanofluids as far as thermal efficiency is concerned. It is also heeded that the rate of mass transfer is proliferated for the surface catalyzed parameter. A comparison table in a limiting case is also supplemented to jazz up the justification of the presented model.

Performance-based numerical appraisal of hybrid and nanofluid flows with Cattaneo-Christov heat flux model in a rotating frame with thermal stratification

Performance-based numerical appraisal of hybrid and nanofluid flows with Cattaneo-Christov heat flux model in a rotating frame with thermal stratification

Comparative study of hybrid and nanofluid flows over an exponentially stretched curved surface with modified Fourier law and dust particles

Hybrid nanofluids are the prospective liquids that possess improved heat transfer enactment and thermophysical characteristics than conventional heat transfer fluids (water, oil, ethylene glycol) and single-particle nanoparticle immersed nanofluids. Here, a comparison of the hybrid nanofluid comprising copper, copper oxide nanosized particles with ethylene glycol (Cu-CuO/C2H6O2) as the customary liquid, with nanofluid copper-ethylene glycol (Cu/C2H6O2) is made. The flow of hybrid nanofluid is considered over an absorbent curved sheet which is stretched exponentially with dust particles with modified Fourier law. The modeled problem is assisted by the melting heat and second-order slip boundary conditions. The system of equations is coped numerically after applying the boundary layer theory to the system of governing equations. It is witnessed that dust phase and temperature are augmented for escalating estimations of the curvature parameter. It is also perceived that an escalation in the thermal relaxation and concentration parameter values results in a lowering temperature of the fluid. Furthermore, it is remarked that fluid velocity is enhanced for large disk curvature. The hybrid nanofluid in case of heat transfer comparison is far ahead of the nanofluid. The acquired outcomes are also endorsed by making a comparison with a published study. An outstanding agreement is attained.

О влиянии выбора численного потока на решение задач с ударными волнами разрывным методом Галеркина

The paper compares various numerical flows in the calculation of flows with the presence of shock waves by first-order schemes and second-order DG method on schemes from the Quirk’s list, namely: the Quirk problem and its modifications, shock wave diffraction at a 90 degree angle, the problem of double Mach reflection. It is shown that the use of HLLC and Godunov’s numerical flows in calculations can lead to instability, the Rusanov-Lax-Friedrichs flow leads to high dissipation of the calculation. The most versatile in carrying out production calculations are hybrid numerical flows, which allow suppressing the development of instabilities and maintaining the accuracy of the method.

Comparative study of hybrid and nanofluid flows amidst two rotating disks with thermal stratification: Statistical and numerical approaches

The flow of nanofluids is of great importance because of their substantial industrial usage and alluring heat transfer capabilities. Recently, an innovative notion namely “hybrid nanofluid” has replaced the customary nanofluid flows to further enhance the heat transfer capabilities. We in this envisaged mathematical model are heading in the same direction and are intended to present a comparative analysis of the heat transfer competence of two time-dependent fluid models namely; hybrid nanofluid (Copper–Iron Oxide, Manganese- Zinc ferrite/Diathermic oil) (Cu-Fe2O4, Mn-ZnFe2O4/DO) and simple nanofluid (Mn-ZnFe2O4/DO) flows amidst two rotating disks in a porous media with Darcy-Forchheimer effect. The subject flows are assisted by the thermal stratification with nonlinear radiation effects. A blend of numerical “bvp4c” and statistical “Response Surface Method (RSM)” approaches is utilized to analyze the envisioned mathematical model. Tabulated and graphical depiction of the outcomes is given to comprehend their appraisal. It is comprehended that the radiation and thermal stratification parameters possess differing trends for the fluid temperature profile. Furthermore, it is observed that the parameter estimation and significance indicate both skin friction coefficient models are similar. The fitted model for skin friction and Nusselt number are the best fit where the normality assumption is satisfied.

An integrated process‐based model of flutes and tool marks in deep‐water environments: Implications for palaeohydraulics, the Bouma sequence and hybrid event beds

AbstractFlutes and tool marks are commonly observed sedimentary structures on the bases of sandstones in deep‐water successions. These sole structures are universally used as palaeocurrent indicators but, in sharp contrast to most sedimentary structures, they are not used in palaeohydraulic reconstructions or to aid prediction of the spatial distribution of sediments. Since Kuenen's famous 1953 paper, flutes and tool marks in deep‐water systems have been linked to turbidity currents, as reflected in the standard Bouma sequence taught to generations of geologists. Yet, these structures present a series of unaddressed enigmas. Detailed field studies in the 1960s and early 1970s observed that flutes are typically associated with thicker, more proximal beds, whilst tools are generally prevalent in thinner, more distal, beds. Additionally, flutes and tool marks are rarely observed on the same surfaces, and flutes are seen to change downstream from larger wider parabolic to smaller narrower spindle‐shaped forms. No model has been proposed that explains these field‐based observations. This contribution undertakes a radical re‐examination of the formative flow conditions of flutes and tool marks, and demonstrates that they are the products of a wide range of sediment gravity flows, from turbulent flows, through transitional clay‐rich flows, to debris flows. Flutes are not solely the product of turbulent flows, but can continue to form in transitional flows. Grooves are shown to be formed bydebris flows, slumps and slides, not turbidity currents, and in many cases the debris flows are linked to the debritic component of hybrid flows. Discontinuous tool marks, including skim (bounce) marks, prod marks and skip marks, are shown to be formed by transitional mud‐rich flows. Consequently, the observed spatial distribution of flutes and tool marks can be explained by a progressive increase in flow cohesivity downstream. This model of flutes and tool marks dovetails with models of hybrid flows that predict such a longitudinal increase in flow cohesivity. However, some deposits show grooves preferentially associated with BoumaTAbeds, and these are likely formed by flows transforming from higher to lower cohesion, and are present in basins where hybrid beds are absent or rare. The recognition that sole structures may haveno genetic linkto the later overlying turbidity current deposits, and can be formed by a wide range of flow types, indicates that the existing pictorial description of the Bouma sequenceis incorrect. A modified Bouma sequence is proposed here that addresses these points. In utilizing the advances in fluid dynamics since Kuenen's pioneering research, this study demonstrates that it is possible to use flutes and tool marks to interpret flow type at the point of formation, the nature of flow transformations, and the mechanics of the basal layer. These advances suggest that it is then possible to predict the nature of deposit type down‐dip. This new understanding, in combination with further testing in outcrop of the proposed relationships between sole marks and palaeohydraulics, opens up a wealth of possibilities for improving the understanding of deep‐water clastic environments, with implications for developing more complete facies models, assessing subaqueous geohazards and the resilience of seafloor infrastructure, and advancing our understanding of deep‐water sediments as archives of palaeoenvironmental change.

From marine bands to hybrid flows: Sedimentology of a Mississippian black shale

AbstractOrganic‐rich mudstones have long been of interest as conventional and unconventional source rocks and are an important organic carbon sink. Yet the processes that deposited organic‐rich muds in epicontinental seaways are poorly understood, partly because few modern analogues exist. This study investigates the processes that transported and deposited sediment and organic matter through part of the Bowland Shale Formation, from the Mississippian Rheic–Tethys seaway. Field to micron‐scale sedimentological analysis reveals a heterogeneous succession of carbonate‐rich, siliceous, and siliciclastic, argillaceous muds. Deposition of these facies at basinal and slope locations was moderated by progradation of the nearby Pendle delta system, fourth‐order eustatic sea‐level fluctuation and localized block and basin tectonism. Marine transgressions deposited bioclastic ‘marine band’ (hemi)pelagic packages. These include abundant euhaline macrofaunal tests, and phosphatic concretions of organic matter and radiolarian tests interpreted as faecal pellets sourced from a productive water column. Lens‐rich (lenticular) mudstones, hybrid, debrite and turbidite beds successively overlie marine band packages and suggest reducing basin accommodation promoted sediment deposition via laminar and hybrid flows sourced from the basin margins. Mud lenses in lenticular mudstones lack organic linings and bioclasts and are equant in early‐cemented lenses and in plan‐view, and are largest and most abundant in mudstones overlying marine band packages. Thus, lenses likely represent partially consolidated mud clasts that were scoured and transported in bedload from the shelf or proximal slope, as a ‘shelf to basin’ conveyor, during periods of reduced basin accommodation. Candidate in situ microbial mats in strongly lenticular mudstones, and as rip‐up fragments in the down‐dip hybrid beds, suggest that these were potentially key biostabilizers of mud. Deltaic mud export was fast, despite the intrabasinal complexity, likely an order of magnitude higher than similar successions deposited in North America. Epicontinental basins remotely linked to delta systems were therefore capable of rapidly accumulating both sediment and organic matter.

Climate, sea level and tectonic controls on sediment discharge from the Sepik River, Papua New Guinea during the Mid- to Late Pleistocene

Amongst the rivers draining the mountainous islands of the Indonesian Archipelago, the Sepik River of Papua New Guinea is the largest contributor of solute and particulate material to the world ocean. Sites U1484 and U1485, drilled during International Ocean Discovery Program (IODP) Expedition 363 provide a continuous, ~555 kyr long, high-resolution record of mainly siliciclastic slope sedimentation on the northern continental margin of PNG, just offshore the mouth of the Sepik River. Sedimentological analysis, based on a combination of smear slide petrography, particle size analysis, high-resolution physical properties track data and visual core description, offers an unprecedented opportunity to investigate the evolution of this major tropical river throughout changing climate and sea-level conditions during the mid- to late Pleistocene. The Sites U1484 and U1485 sediment records exhibit a dramatic lithologic change at ~ 370 ka: the oldest deposits are dominated by pelagic mud, suggesting that the coarser-grained terrigenous discharge from rivers draining the New Guinea Highlands (including a “proto” Sepik River) was captured before reaching the ocean, when the Sepik River basin was an epicontinental sea. The occurrence of coarser-grained, mass-gravity (mainly hybrid) flows after ~370 ka suggests that the epicontinental sea became a more restricted, shallow-water to nonmarine basin, probably due to both basin infilling and the uplift of local coastal ranges. During the last three glacial-interglacial cycles (~300 kyr), this shallow inland basin was strongly affected by global variations in sea level: during sea level lowstands, the Sepik River cut into older sediments and discharged further offshore onto the shallow continental margins, promoting mass-gravity flows. Pelagic mud deposition on the continental margin during the most extreme highstands following deglaciations suggests a return to shallow marine conditions in the Sepik Basin and repositioning of the river mouth further inland, away from the shelf and from the location of the IODP sites. This also indicates that variations in terrigenous fluxes during these extreme highstands were not solely controlled by the intensity of the hydrological cycle and that global sea level variations also influenced sediment deposition. The sequence is interrupted by several massive grain flow deposits, occurring diachronously at Sites U1484 and U1485 and related to a period of intensified tectonic activity between ~280 ka and ~140 ka. The sedimentologic characteristics of these mass-gravity deposits and their lack of correlation between sites are interpreted as resulting from channelized flows along margin-parallel, fault-controlled channels caused by local and regional failures of the continental margins including the area of the Yalingi Canyon, ~50 km north of the sites, where large tsunamigenic events have also occurred in recent years. Time series analyses of magnetic susceptibility and natural gamma radiation (proxies for %sand and %clay content, respectively) indicate that river discharge fluxes were modulated at orbital frequencies (including obliquity-scale cycles), which suggests that precipitation and river discharge were not only linked to precessionally driven shifts in the mean position of the Intertropical Convergence Zone, but also to high-latitude climate change.

Social media as public opinion: How journalists use social media to represent public opinion

Public opinion, as necessary a concept it is to the underpinnings of democracy, is a socially constructed representation of the public that is forged by the methods and data from which it is derived, as well as how it is understood by those tasked with evaluating and utilizing it. I examine how social media manifests as public opinion in the news and how these practices shape journalistic routines. I draw from a content analysis of news stories about the 2016 US election, as well as interviews with journalists, to shed light on evolving practices that inform the use of social media to represent public opinion. I find that despite social media users not reflecting the electorate, the press reported online sentiments and trends as a form of public opinion that services the horserace narrative and complements survey polling and vox populi quotes. These practices are woven into professional routines – journalists looked to social media to reflect public opinion, especially in the wake of media events like debates. Journalists worried about an overreliance on social media to inform coverage, especially Dataminr alerts and journalists’ own highly curated Twitter feeds. Hybrid flows of information between journalists, campaigns, and social media companies inform conceptions of public opinion.

A Hybrid Dispersed-Large Interface Solver for multi-scale two-phase flow modelling

Hybrid multiphase flows are flows with both dispersed phase and large scale structures, and generally have a wide range of interfacial length scales. Such flows are common in industrial flow problems and nuclear engineering applications. Appropriate modelling of these scales, ranging from the dispersed to the segregated flow regime, becomes important as they all contribute to the overall behaviour of the flow physics. Conventional two-fluid, two-field Eulerian-Eulerian solvers have been known to neglect important aspects of flow physics and are unable to reproduce such hybrid flows. A systematic benchmark of a hybrid solver named Hybrid Dispresed-Large Interface Solver (HD-LIS) is presented here. A flow regime map based on the gas volume fraction is utilised in the present solver in order to distinguish between dispersed and segregated flow regimes and for application of the appropriate physical models and numerical schemes in each regime. The modelling of segregated regime includes an appropriate drag force, interface compression scheme, and turbulence damping, while modelling of the dispersed regime considers both drag and non-drag momentum exchange forces. In addition, the use of total variation diminishing (TVD) numerical schemes and semi-implicit temporal discretization approach ensures boundedness and robustness of the solver. The present benchmark includes a wide spectrum of test cases, selected to test the ability of the solver in fundamental modelling of dispersed phase or large scale interfaces These validation cases include single bubble and droplet dynamics, flow regimes transition (between dispersed and plug flows), free-surface impact jet, and two-phase shear flows. It is shown that the present solver is able to qualitatively reproduce both dispersed and segregated flow physics well. As will be demonstrated, HD-LIS differs from other existing Eulerian-Eulerian two-fluid solvers which are reported in literature in respect to the applied numerical schemes and physical models. This selection of schemes and models is shown to make the solver suitable for modelling of underlying flow physics exhibited by dispersed flows and large-scale interfaces. Although the validation cases presented herein offer limited flow complexity, the present solver is considered a step towards a more comprehensive hybrid solver.

Co-genetic, cohesive and non-cohesive delta front facies: A case study of flow transformation in a lacustrine setting, Camaquã Basin, southernmost Brazil

Sediment gravity flows comprise gravity-driven underflows with a large concentration of suspended load. Along the downslope transport, flow transformations from laminar to turbulent conditions or vice-versa can take place due to several factors, including the incorporation and segregation of clay into, or from the flow. These flow changes may produce hybrid behavior and resulting hybrid event beds. Flow transformation and hybrid events are widely discussed in marine settings, but studies on lacustrine environments are rare. The Ediacaran Western Santa Bárbara Rift represents one stage of the development of the Camaquã Basin and includes both cohesive (debrites) and non-cohesive (turbidites) gravity flow deposits associated with braidplain deltas deposited in shallow lake. A range of cohesive and non-cohesive density flow facies is here discussed in terms of triggering mechanism, genetic processes and related flow transformations. The analysis of aerial images combined with outcrop descriptions allowed the identification and mapping of key stratigraphic surfaces and therefore associated systems tracts. Sedimentological and gamma-ray logs, sampling and laboratory analyses (optical microscopy, X-ray diffraction –XRD - and Scanning Electron Microscopy – SEM) were performed to define facies and facies associations. Microscopy was useful to identify vermiculite as an important matrix component. The position of distinct facies within the genetic stratigraphic framework allowed the construction of a generalized facies tract model. The basinward shift of facies indicates three flow transformations, in addition to hybrid flows. Substrate erosion, and ensuing incorporation and fragmentation of mud clasts into turbulent flows caused changes from fluidal to plastic flow rheology. Generalized facies tracts suggest fluvial floods (and resulting hyperpycnal flows) as the triggering mechanism for the subaqueous density flows herein described.

Bond graph approach for port-controlled Hamiltonian modeling for SST

Energy-based modeling is often very appropriate for physical system modeling for development and analysis of multi domain dynamic system models. One such tool for modelling of system is bond graph (BG), which allows to model complex system, with clear interconnection rules and preserving the physical structure of the system. In various engineering system, operation is carried out on various time scale. One such area of generic system is microgrid, where multidisciplinary microgrid components operating on various time scales. In such hybrid system, flows and efforts comprise a very good choice of variables to link components for system stability and performance analysis. Since components are typically connected through various power electronics devices, mathematical modeling capable of capturing high frequency behavior is of utmost concern in stability analysis. Solid state transformer (SST) is one such device playing a key role in bi-directional power flow between the grid and various renewable sources. This paper proposes the use of the BG approach to recognize the energy representation of the microgrid in port-Hamiltonian form by looking at the energy transformation aspects of microgrid components. The port-controlled Hamiltonian systems (PCHS) are the mathematical description of bond graphs which allows integration of subsystems of hybrid microgrid using energy as the linking concept. To illustrate the utility of BG in hybrid systems, basic PI controller is implemented. The aim of the paper is to show how to model complex systems in bond graph domain.

Africa's Narrative Geographies: Charting the Intersection of Geocriticism and Postcolonial Studies by Dustin Crowley

Reviewed by: Africa's Narrative Geographies: Charting the Intersection of Geocriticism and Postcolonial Studies by Dustin Crowley Sten Pultz Moslund (bio) Dustin Crowley. Africa's Narrative Geographies: Charting the Intersection of Geocriticism and Postcolonial Studies. New York: Palgrave, 2015. Pp. x, 192. €84.29. Dustin Crowley's Africa's Narrative Geographies: Charting the Intersection of Geocriticism and Postcolonial Studies is the seventh title in the pathbreaking series on geocriticism and spatial literary studies published by Palgrave Macmillan and edited by Robert T. Tally Jr. Crowley's contribution revisits the expansive study in postcolonial literature of geographies of imperialism and liberation. He does so in ways that will be recognizable to many experts in the field but also includes new insights and a welcome challenge to any tendency to conceptual complacency within the poststructural thrust of spatial studies in literature. Crowley positions his book against the heavy influence of "postmodernist and post-structuralist sentiments and assumptions" in geocriticism (3), which privilege notions of indeterminacy, transgression, difference, anti-essentialism, and nomadic identities (he points out the work of Edward Soja, Gilles Deleuze, and Bertrand Westphal, among others). Throughout the book, Crowley demonstrates the downside to this influence in readings of spatial representations in African literature. In the worst cases, we are left with a limited vision of rather abstract spatialities imprinted by abstract deconstructive notions of liberty as destabilization, migration, and hybrid flows or "rhizomatic disorder" (8), and, consequently, predictable and dichotomizing responses to questions of place-related phenomena like nationalism, stability, borders, and locality. As a corrective response to the poststructural slant and drawing loosely on authors including David Harvey, Doreen Massey, and Lawrence Buell, Crowley proposes a geocritical approach to literature that operates with the three (loosely defined) concepts of scale (local, national, regional, or global), place (as formed by a complex and reciprocal intertwinement of historical, social, and natural conditions and materialities), and space (a catalyst of multiple and ongoing "relational flows . . . of people, materials, [and] discourses" [26]). The book's conjunction of scale, place, and space motivates a [End Page 160] flexible and complex understanding of the production of place and calls for a comprehensive analysis of several shifting, reinforcing, and contradictory aspects and dimensions in the formation and representation of placial realities and geographical imaginaries in literature. One of the strengths of Africa's Narrative Geographies is Crowley's attentiveness to and illustrations of how "the nature of place provides the means for both hegemonic control and the challenge to hegemony" (24), which inspires a perspective that precludes any easy dissociation of resistance and liberation from the power to dominate. This perspective is also capable of illustrating globalism, localism, nationalism, antinationalism, etc. as both repressive and liberating place-shaping forces. After an introductory chapter of thirty pages, Crowley engages his geocritical perspective in readings of a well-chosen selection of literary works by five African authors: Léopold Sédar Senghor, Ngũgĩ wa Thiong'o, Bessie Head, Nuruddin Farah, and Chris Abani. The choice of texts represents a diversity of historical and geographical contexts, and while Crowley approaches each writer from a particular angle of concern, all of his readings relate to the central question of literary encounters with "dominant spatialities" and how to "imagine alternative spaces and places of freedom and dignity" (3). Crowley analyses Senghor's négritude poetry for its pan-African construction of the continent as a unified place and probes into questions of cultural essentialism and its overlap with homogenising representations of places and geographies. With attention to The River Between, A Grain of Wheat, Wizard of the Crow, and I Will Marry When I Want, Crowley examines the place world and spatial imaginaries in Ngũgĩ's narratives for how they bring together international Marxism and anti-imperialism with the particularity of local cultural nationalisms, which forges a literary vision in Ngũgĩ's work of a culturally grounded heterogeneous nation. Interactions between local and global scales are pivotal in the succeeding analyses, too. In discussing Head's A Question of Power, Maru, and the non-fictional Bewitched Crossroad, Crowley focuses on boundaries, migration, and exile. He identifies global humanism as fused with a sense of local emplacement and exilic...