Trajectories Of Inclusions Research Articles

Numerical Investigation of Inclusion Behaviour in a Multi-Strand Tundish During Strand Blockages

Inclusion removal in the continuous casting tundish is an essential technology for production of high-grade steels. In the present study, a three dimensional numerical investigation has been carried out on six strand delta shape tundish. The aim of the work is to investigate the inclusion entrapment and removal phenomenon in a tundish. A parametric study has been carried out to study the behavior of the inclusions in a steelmaking tundish and the results have been compared on the basis of densities and diameters of inclusions. Bare tundish as well as a tundish occupied with Advance Pouring Box (APB) have been studied to predict the transport behavior of inclusion particles. Further, effect of strand blockages has been considered. The turbulent Navier–Stokes equations have been solved to predict the flow velocity distributions and inclusion trajectories were calculated using a Lagrangian particle tracking method. The numerical results were validated using available experimental results and found to be in good agreement. The results indicate that the use of APB has changed the fluid flow pattern and consequently the inclusion particles movement. The density of inclusion particles plays an important role. It has been seen that low dense particles have higher chances to get trapped or removed from tundish. It was also found that larger diameter of inclusion particles have more chances of floatation.

Disparities in infrastructure as a barrier to attain faster inclusive growth trajectory: an inter-state analysis

The present paper attempts to explore and examine the relationship between disparity in infrastructure and its relationship with Per-Capita Income (PCNSDP) across 15 major states of India from 1966–67 to 2011–12. The estimated results reveal that, there is a significant and positive relationship between infrastructure development to economic development as measured by per capita income of state. Higher infrastructure development leads to higher development for instance in Kerala, Punjab, AP, Tamil Nadu, Gujarat, Haryana and Maharashtra states. Poor infrastructure development supporting to the bigger levels poverty ratio, the deprivation of productivity and standard of living etc., for example in Bihar, UP,. MP, Assam, Rajasthan and Orissa. The states with lagged Infrastructure facilities facing acute crunch of basic amenities as compared to better infrastructure developed states, which in turn to leads rising socio-economic disparities across the states. Therefore deficit in the infrastructure is the major hurdle for the attaining inclusive growth. Following from this, to attaining growth with inclusiveness in income and non-income indices, reduction of infrastructure disparities across the sectors, sections and regions in the state and across the states in India should be accorded top priority.

Structural Transformation for Inclusive Development in Africa: The role of active government policies

This study examines the relationship between structural economic transformation and the economic, social and political dimensions of inequality. It is motivated by the renewed emphasis by policymakers in Africa to adopt a more inclusive growth trajectory through commodity-based industrialization. Drawing on theoretical and empirical evidence, the study shows that structural transformation is not a sufficient condition for inclusive growth. Indeed, even though structural transformation can result in poverty reduction, in the absence of active policies, the latter often coexists with rising inequalities. Active government policies that improve social service delivery, enhance agricultural sector productivity, minimize ethnic and gender inequalities, and strengthen social protection programmes are key to an inclusive structural transformation agenda.

Arriving on a Different Shore: US Empire at Its Horizons

As settler-colonial studies makes inroads into methodologies shaping evolving field of global Indigenous studies, curious thing has happened. Where once local and discrete marked singularity of disciplined studies, there are now calls for trans- and inter-cultural, indigenous, minoritarian, and disciplinary analyses to account for differences that subjectivities and subject positions make within violences of racialization and colonization. In context of United States, nation-state formation that makes comparative scope of essays gathered here cohere, histories of racialization and colonization have often been assumed to signify same thing. Regardless of specific label used to describe historical oppression, both are assumed to be same systematic process of othering that leads to incarceration, dispossession, disenfranchisement, and alienation within and away from larger sociopolitical communities reser ved for only select few.Certainly, as authors within this special issue can attest, what unifies transoceanic and transcontinental scope of United States' fifty states is violence through which those lands, along with people who have inhabited them, have been captured within larger political, economic, and cultural nomos of continental governmentality that has been under development since discovery of New World. Within these circuits of comparative logics that these essays have charted, then, are number of embedded assumptions. First, that settler colonialism provides conditions of possibility for encounters and that those encounters have potential to be resistant. Second, that histories of militarism and incarceration in United States build affective relationships across those experiences, especially through horizontal vectors that operate outside and beside machinations of state-sponsored land grabs. Third, that multiculturalism collapses difference into smooth trajectories of inclusion and asylum that have depended upon narratives of vanishing and indigenous dispossession. And finally, that quotidian experiences of exclusion have intimate implications that structure and suture desire, identification, and relationship with and across divisions and fractures created through discrete and local experiences of oppressions.By prioritizing sites of alternative between Asian Americans and indigenous peoples whose lands now comprise United States, including Hawai'i and Alaska, authors here seek to theorize those moments of convergence where specific histories of internment, labor, and dispossession collide with realities of an ongoing colonialism. In introduction, editors of this special issue suggest that methodological questions shaping their call for interrogating contrapuntal (after Edward Said and Mary Louise Pratt) zones (14) of United States empire center upon the move beyond settler-indigenous binary to more fruitful consideration of other forms of contact (9). Proposing juxtaposition as a hermeneutic of alternative contact, Carpenter and Yoon demonstrate that such methodology allows us to arrange and test different meanings that occur when put side by side and to clear space for subaltern voices perceived to be silent or foreclosed to peek through cracks, between lines of reportage and representation (10). Such cacophonous simultaneity, one might be tempted to observe, helps scholars consider how colonization of indigenous lands and peoples by United States functions not so much as binary between settlers and natives but through series of recognitions and misrecognitions that coerce settlers, arrivants, and natives into service as proxies, agents, and at times beneficiaries, however undesired and unwanted, of processes that have stripped land, lives, and nations away from indigenous peoples who have always been here. …

Behavior of Non-metallic Inclusions in a Continuous Casting Tundish with Channel Type Induction Heating

A generalized three dimensional mathematical model, which adopted the Euler-Lagrange approach, has been developed for the motion of inclusions in a continuous casting tundish with channel type induction heating. The inclusion trajectories were obtained by numerical solution of the motion equation including gravity, buoyancy, drag, lift, added mass, Brownian, electromagnetic pressure and thermophoretic forces. Besides, the collision and coalescence of inclusions and adhesion to the lining solid surfaces were also taken into account. The Brownian, Stokes and turbulent collision were clarified, separately. Then the effect of induction heating power on the inclusion behavior was demonstrated. A reasonable agreement between the experimental observation and numerical results was obtained. The results indicate that the electromagnetic pressure force significantly promotes the removal of inclusions, especially for the bigger inclusion. Although the thermophoretic force goes against the removal of inclusions, its influence is negligibly small. The removal ratio of inclusions in the tundish with induction heating increases from 67.45% to 96.43%, while the power varies from 800 kW to 1200 kW. The collision and coalescence should be included when model the inclusion motion, because it can promote the removal of inclusion. The turbulent and Brownian collision becomes more active with the increasing power, while the Stokes collision is just opposite.

Filippov’s selection theorem and the existence of solutions for optimal control problems in time scales

We obtain an extension of Filippov’s Lemma to control systems in time scales, where the multifunction associated with the dynamics is delta measurable on time and Lipschitz on the state variable. Using a modified version of a recent result on compactness of the set of trajectories for inclusions on time scales, in combination with the Filippov’s selection theorem obtained here, we prove the existence of solutions to optimal control problems in time scales. At the outset, we provide some measurability properties for functions and multifunctions defined in time scales.

Influence of electromagnetic stirring on transport phenomena in round billet continuous casting mould and macrostructure of high carbon steel billet

The characteristics of magnetic field, flow field, temperature profile and inclusion trajectories in a round billet continuous casting mould with electromagnetic stirring (M-EMS) were numerically simulated. An industrial plant trial was conducted to verify the magnetic field characteristics and investigate the influence of M-EMS on the solidification macrostructure of high carbon steel. The results indicate that the predicted magnetic field was in good agreement with the measured data, and the velocity patterns, temperature, inclusion trajectory distributions and macrostructure of steel are significantly modified using M-EMS during casting.

Hölder estimates for trajectories of differential inclusions and HJB equations with state constraints

We consider the differential inclusion \({\dot x \in F(t, x)}\), with F measurable in t and Lipschitz in x, together with the state constraint \({x(t) \in \Omega}\) and prove the existence of neighboring trajectories lying in the interior of Ω. Using this result, we can characterize the Value Function of the Bolza Problem as the unique lower semicontinuous solution to the corresponding Hamilton–Jacobi–Bellman equation.

Absolute continuity and existence of solutions to dynamic inclusions in time scales

We provide some properties for absolutely continuous functions in time scales. Then we consider a class of dynamical inclusions in time scales and extend to this class a convergence result of a sequence of almost inclusion trajectories to a limit which is actually a trajectory of the inclusion in question. We also introduce the so called Euler solution to dynamical systems in time scales and prove its existence. A combination of the existence of Euler solutions with the compactness type result described above ensures the existence of an actual trajectory for the dynamical inclusion when the setvalued vector field is nonempty, compact, convex and has closed graph.

Inclusion Behavior During the Electron Beam Button Melting Test

The high mechanical performance of alloys developed for the manufacture of turbine disks depend upon the size and the number density of the inclusions. The electron beam button method has been practiced since the 1980s as a technique to quantify the cleanliness of the superalloys as well as to identify the nature and the size of the inclusions. The technique involves melting the sample into a hemispherical water-cooled crucible and the low density inclusions (mainly oxides) are concentrated by a combination of Marangoni and buoyancy forces into an area at the top surface of the button referred to as the raft. We have experimentally studied the behavior of oxide inclusions in special steels using both high definition video and infrared cameras. We have observed the inversion of the Marangoni effect due to the presence of sulfur, which leads to a positive temperature coefficient of the surface tension. A mathematical modeling has been carried out to simulate the turbulent fluid flow associated with the temperature field in the metallic pool of the button. The surface temperature profile has been successfully compared with the measured data. A post-processor numerical tool calculates the inclusion trajectories taking into account the turbulent fluctuation velocity by a stochastic approach. Hence, the behavior of a population of inclusions has been statistically studied, and the dependence of the capture efficiency on the inclusion size has been analyzed.

Trajectories of differential inclusions with state constraints

The paper deals with solutions of a differential inclusion x ˙ ∈ F ( x ) constrained to a compact convex set Ω. Here F is a compact, possibly non-convex valued, Lipschitz continuous multifunction, whose convex closure co F satisfies a strict inward pointing condition at every boundary point x ∈ ∂ Ω . Given a reference trajectory x ⁎ ( ⋅ ) taking values in an ε-neighborhood of Ω, we prove the existence of a second trajectory x : [ 0 , T ] ↦ Ω which satisfies ‖ x − x ⁎ ‖ W 1 , 1 ⩽ C ε ( 1 + | ln ε | ) . As shown by an earlier counterexample, this bound is sharp.

Three-Dimensional Magnetohydrodynamic Calculation for Coupling Multiphase Flow in Round Billet Continuous Casting Mold With Electromagnetic Stirring

A 3-D combined finite element-finite volume for magnetohydrodynamic (MHD) calculation method considering the coupling flow field, heat transfer, and inclusion trajectory was developed, and the flow characteristics of molten steel and inclusion trajectory in round billet mold using electromagnetic stirring (EMS) were numerically investigated. The calculation results of magnetic field and temperature in the mold are in a good agreement with the measured data. The influence of EMS on the turbulent flow and temperature in the mold is estimated by the model, which shows that EMS has an obvious effect on the flow and temperature distribution of molten steel, and the macrostructure of the billet.

Existence of equilibria of set-valued maps on bounded epi-Lipschitz domains in Hilbert spaces without invariance conditions

In this paper, we provide a new result of the existence of equilibria for set-valued maps on bounded closed subsets K of Hilbert spaces. We do not impose either convexity or compactness assumptions on K but we assume that K has epi-Lipschitz sections, i.e. its intersection with suitable finite dimensional spaces is locally the epigraph of Lipschitz functions. In finite dimensional spaces, the famous Brouwer theorem asserts the existence of a fixed point for a continuous function from a compact convex set K to itself. Our result could be viewed as a kind of generalization of this classical result in the context of Hilbert spaces and when the function (or the set-valued map) does not necessarily map K into itself ( K is not invariant under the map). Our approach is based firstly on degree theory for compact and for condensing set-valued maps and secondly on flows generated by trajectories of differential inclusions.

Numerical Studies on the In-situ Measurement of Inclusions in Liquid Steel Using the E.S.Z. or LiMCA Technique

The direct detection of inclusions first became possible for electronically conducting fluids following the development of the LiMCA (Liquid Metal Cleanliness Analyzer) technique. The principle of this technique is based on the R.P.T. (Resistive Pulse Technique), or E.S.Z. (Electric Sensing Zone) method, for counting, and sizing, inclusions in liquids. Its application to steel melts is now studied theoretically, in order to help in the understanding and analysis of in-situ experimental measurements of inclusion size and frequency distributions in steel plant processing operations.In developing the theoretical model for this technique, a three-step strategy was used to explore physical events that take place within the electric sensing zone, as an inclusion passes through. First, a multiphase flow model was required, in which events that can take place during the passage of the inclusion through the sensor's ESZ were considered. Inclusion trajectories and transit times were predicted using a particle momentum equation. For this, Newton's Second Law of motion was solved, in which the mass and instantaneous acceleration of the particle was balanced against the sum of the various forces acting on the particle/inclusion, during its passage through the ESZ. The forces summed included Stokes's drag, fluid acceleration, particle acceleration with added mass, gravitational and, in particular, the external self-conducting electromagnetic force induced by passing a heavy direct current through the ESZ of an electronically conducting liquid.In the second step of this theoretical analysis, a numerical potential-integral method was conceived in order to calculate local changes in electrical resistance within an ESZ of variable geometry, and variable location of a traversing particle. This new approach was compared to alternative analytical and numerical estimates of changes in ESZ resistivity with a second phase particle within it, which neglects the effects of radial position of the particle.In the third and final step in the present analysis, parabolic, fluted, and cylindrical ESZ's were selected, and the influence of fluid properties, ESZ dimensions, electric currents, and the inclusion's properties (electrical conductivity, density, size, shape, etc.), were investigated to determine how these various parameters affect the resistive (or voltage) pulses generated during the passage of an inclusion through the ESZ.

Exclusão escolar e a criança de circo

This article presents approach the circus artist child schooling. The concerning focus is to observe his inclusion and no inclusion trajectory at school. The main objective is to observe the child`s day by day life and identify obstacles that may interfere in school education. Interviews with parents and children were used as methodology. Four circuses were observed during two years in Belo Horizonte - Minas Gerais presentations season. After two years the research results ends up into the necessity to change the school behavior pedagogical methodology and inclusion comprehension focus to deal with those children. Prejudice and a non adequate educators training were also noticed. Key words : circus child, legislation, inclusion at school

<i>Chinese Americans and the Politics of Race and Culture</i> (review)

Reviewed by: Chinese Americans and the Politics of Race and Culture Min Zhou Chinese Americans and the Politics of Race and Culture. Edited by Sucheng CHANMadeline Y. HSU. Philadelphia, PA: Temple University Press, 2008. Pp. xx, 266. History and historiography have been central in the emerging field of Chinese American studies. This anthology, edited by Sucheng Chan and Madeline Hsu, uses a cultural history framework that weaves together personal narratives, family histories, case studies, and event analyses to show the lives of Chinese Americans “in more complex, intricate, and intriguing ways” (p. xvi). Sucheng Chan’s introductory chapter offers an excellent and comprehensive literature review to demonstrate the synergy in Chinese American history and historiography. Chan identifies five periods of Chinese American historiography: partisan writings between the 1850s and the early 1920s, social science studies in the mid-1920s to the 1960s, works by Asian American and European American scholars in the late 1960s to the early 1980s, works by university-based historians between the mid-1980s and the early 1990s, and cultural histories since the late 1990s. Chan focuses on three genres in the works of the pre-Asian American Movement — partisan tracts, social science studies, and Chinatown “guides” or exposés (p. 2). She plows widely and digs deeply into the field of Chinese American studies, not merely showing readers what has been done but also paying attention to the legacy of the Asian American Movement and raising profound issues of great theoretical import and practical significance. As always, Chan takes issue with two prevailing perspectives — that of victims being exploited in the United States and that of agents and decision makers capable of making sensible choices that shape their lives. Her actor-oriented approach shows how individuals make history and initiate adaptive responses to the social, economic, and political milieu in which they find themselves. Her passionate and extraordinary commitment to building and defending Chinese American studies and Asian American studies is remarkable. I cannot think of another scholar of Chinese American studies who covers such a broad range of topics, and who always successfully connects the human dimension to the key philosophical and social science concerns. Chan’s introduction is without a doubt a useful guide to the vast literature on Chinese American history and historiography. The anthology consists of seven chapters arranged in chronological order. The chapter by Mae Ngai, “History as Law and Life,” tells the story of a Chinese immigrant family from the late 19th to early 20th century. Ngai questions the canonical assumption that all immigrants necessarily follow a general path of Americanization, socioeconomic mobility, and political inclusion. She points to [End Page 294] the limits of the democratic-political culture in the incorporation of immigrants and argues that the trajectories of exclusion and inclusion are closely entwined. Through her analysis of an 1885 civil rights case, Tape v. Hurley, in which the California Supreme Court ruled that Chinese children could not be excluded from public schools, Ngai demonstrates how the two trajectories converged in a process of ethnic middle-class formation as the legal status of the Chinese in America was being adjudicated in court. The Tape family was an example of the emerging brokering class of the time. Members of this brokering class, serving as transportation agents, immigration-bonds brokers, labor contractors, and language interpreters, were both liminal and powerful figures. Because they were bilingual and bicultural, they were needed and distrusted by both the Chinese and the Europeans. Indispensable for the resettlement and protection of the immigrant laboring classes, they promoted incorporation while simultaneously invested in the exclusion of the immigrants as a means of achieving wealth and social status. Ultimately the brokers’ involvement in illegal immigration and their advocacy for civil rights were an integral part of their struggle for survival and advancement. The chapter illustrates how immigration and exclusion created a site for wealth accumulation and social status attainment and how the entwined processes of inclusion and exclusion produced constraints for some and opportunities for others within the Chinese American community. Josephine Fowler’s chapter, “The Activism of Left-Wing and Communist Chinese Immigrants, 1927–1933,” builds on Him Mark Lai’s study of activism among...

Effect of Height and Position of Dams on Inclusion Removal in a Six Strand Tundish

The Reynolds-averaged Navier–Stokes equations have been numerically solved to obtain a steady, three-dimensional velocity field inside the six-strand billet caster tundish using the standard k–ε model of turbulence. These steady flow fields so obtained are then used to predict the removal of inclusions from molten steel by solving the inclusion transport equation with the help of a commercial CFD software Fluent 6.1.22. The effects of height and position of dams in the tundish and size of the inclusion particles on percentage inclusion removal were studied. To simulate the chaotic effect of the turbulent eddies on the particle paths; a discrete random walk model was applied during inclusion trajectory calculations. The computational model was first validated with the results reported in the literature a good match was found between the two. It was found that with the increase in the height of the dams, the inclusion removal tendency increased whereas the shifting of the dams towards the outlets decreases the inclusion removal. An increase in the inclusion removal was found with an increase in the inclusion particle size.

Numerical simulation on inclusion transport in continuous casting mold

Turbulent flow, the transport of inclusions and bubbles, and inclusion removal by fluid flow transport and by bubble flotation in the strand of the continuous slab caster are investigated using computational models, and validated through comparison with plant measurements of inclusions. Steady 3-D flow of steel in the liquid pool in the mold and upper strand is simulated with a finite-difference computational model using the standard k-ɛ turbulence model. Trajectories of inclusions and bubbles are calculated by integrating each local velocity, considering its drag and buoyancy forces. A “random walk” model is used to incorporate the effect of turbulent fluctuations on the particle motion. The attachment probability of inclusions on a bubble surface is investigated based on fundamental fluid flow simulations, incorporating the turbulent inclusion trajectory and sliding time of each individual inclusion along the bubble surface as a function of particle and bubble size. The change in inclusion distribution due to removal by bubble transport in the mold is calculated based on the computed attachment probability of inclusions on each bubble and the computed path length of the bubbles. The results indicate that 6%–10% inclusions are removed by fluid flow transport, 10% by bubble flotation, and 4% by entrapment to the submerged entry nozzle (SEN) walls. Smaller bubbles and larger inclusions have larger attachment probabilities. Smaller bubbles are more efficient for inclusion removal by bubble flotation, so long as they are not entrapped in the solidifying shell. A larger gas flow rate favors inclusion removal by bubble flotation. The optimum bubble size should be 2–4 mm.

Inclusion removal by bubble flotation in a continuous casting mold

Fundamentally based computational models are developed and applied to quantify the removal of inclusions by bubbles during the continuous casting of steel. First, the attachment probability of inclusions on a bubble surface is investigated based on fundamental fluid flow simulations, incorporating the turbulent inclusion trajectory and sliding time of each individual inclusion along the bubble surface as a function of particle and bubble size. Then, the turbulent fluid flow in a typical continuous casting mold, trajectories of bubbles, and their path length in the mold are calculated. The change in inclusion distribution due to removal by bubble transport in the mold is calculated based on the computed attachment probability of inclusions on each bubble and the computed path length of the bubbles. In addition to quantifying inclusion removal for many different cases, the results are important to evaluate the significance of different inclusion-removal mechanisms. The modeling approach presented here is a powerful tool for investigating multiscale phenomena in steelmaking and casting operations to learn how to optimize conditions to lower defects.

Steps towards participation: the social support of learning trajectories

In this paper we argue that interventions aimed at preventing social exclusion need to be informed by detailed analysis of the formation, disruption, reformation and support of trajectories of participation in the opportunities for action provided. We draw on evidence we gathered on the lives of two women who used an inner city drop‐in centre to discuss how resilience and trajectories of inclusion are built slowly over time in relationship with others. Using concepts derived from sociocultural psychology and activity theory, we interrogate the evidence to first ask whether there is a pattern of changes in participation over time and to then explore how the identity shifts these changes represent are supported. The analysis reveals that there is a pattern, but it is a pattern of using and giving support which suggests that such trajectories are likely to be recursive. This using and giving of support we term relational agency and argue that a capacity for relational agency, as both the supported and the supporter, is a crucial factor in the development of purposive identities and the building of resilience. We also suggest that it is likely to be encouraged in settings which can foster trust and reciprocity as flexible and open learning zones.