Problem Of Segregation Research Articles

Segregation patterns in binary granular mixtures with same layer-thickness under vertical vibration

Inspired by the theoretical prediction [Phys. Rev. Lett. 86, 3423 (2001)] and the disputed experimental results [Phys. Rev. Lett. 89, 189601(2002), Phys. Rev. Lett. 90, 014302 (2003)] about the problem of granular segregation, we systematically investigate the pattern of binary granular mixtures consisting of same layer-thickness under vertical vibration. Various kinds of mixtures with different diameters and densities particles are poured into the glass cylinder that is sealed and evacuated to an air pressure less than 50Pa to observe separation patterns. It is found that these granular mixtures behave like five kinds of segregation patterns for different driving control parameters, i.e., Brazil nut (BN), reversed Brazil nut (RBN), Mixed states, light-BN (LBN), and light-RBN (LRBN). The latter two regimes are neither purely segregated nor completely mixed states. Moreover, BN phenomenon takes place in the area of low density ratio and found to be independent of layer-thickness, while RBN is sensitive to both the layer-thickness and frequency and occurs at the large density ratio area. Our result may be helpful for the establishment of theory about the segregation and mixing of granular mixtures.

Segregation discovery in a social network of companies

We introduce a framework for a data-driven analysis of segregation of minority groups in social networks, and challenge it on a complex scenario. The framework builds on quantitative measures of segregation, called segregation indexes, proposed in the social science literature. The segregation discovery problem consists of searching sub-graphs and sub-groups for which a reference segregation index is above a minimum threshold. A search algorithm is devised that solves the segregation problem. The framework is challenged on the analysis of segregation of social groups in the boards of directors of the real and large network of Italian companies connected through shared directors.

Exact solution of the problem of dissolved gas segregation by the plane crystallization front

Analytical solution of the segregation problem was found for the arbitrary crystal growth law using the quasi-steady-state approximation. The segregation is caused by the displacement of dissolved gas by moving plane crystallization front. The effect of solidification shrinkage on the crystallization process was taken into account. It is shown that in the case of “equilibrium crystallization” (when the growth rate is in inverse ratio to time) the solution of the problem becomes self-similar. In this case gas concentration at the crystallization front stays the same during the whole process while the diffusion layer thickness increases with time.

Combined Effects of Densified Polystyrene and Unprocessed Fly Ash on Concrete Engineering Properties

The present study evaluated the combined effects of two types of waste materials of expanded polystyrene (EPS) and unprocessed fly ash (FA) on different properties of concrete. A novel recycling technique of densifying waste EPS is used to produce a novel lightweight aggregate (LWA). This new technique has solved the problem of segregation in concrete by coating EPS particles with a natural binder of clay and cement. Nine different concrete mixtures with a water to cement ratio of 0.8 were used. The densified EPS and unprocessed FA were partially replaced with natural aggregate and Portland cement, respectively. The engineering properties, including workability, density, compressive strength, ultrasonic pulse velocity (UPV), and water absorption (WA) were investigated at different curing times. According to the experimental results, there is a decrease in compressive strength and UPV with increasing this novel LWA content in concrete. However, by using a suitable mix design, the utilisation of these two waste materials in concrete using an appropriate recycling technique is possible.

Discrete element method for the prediction of the onset velocity in a spouted bed

Spouted Bed Reactors (SBRs) are currently receiving a lot of attention due to their properties: thanks to the enhanced mass and energy transfer rates and the unique configuration of these reactors, solid particles can be handled with very high efficiency, making them suitable for several applications, such as biomass gasification. Spouted Bed Reactors can also give positive responses to the problem of segregation, which strongly compromises the efficiency of processes involving the handling of heterogeneous mixtures.The aim of this work is to study the behaviour of a spouted bed facility, both experimentally and via simulations performed with the CFD program ANSYS FLUENT, in view of a possible employment of it to assess the scale up criteria or segregation phenomena in spouted beds. The solid phase is simulated enabling the DDPM-DEM model (Dense Discrete Phase Model - Discrete Element Method), commonly known as the Eulerian-Lagrangian approach. The influence of the following physical properties of the particles on the onset velocity was assessed: diameter, sphericity and density. The results of the simulations were compared with those obtained experimentally, for a single solid phase using three different types of inert material (glass, sand and PET) and also for a binary mixture. The model has been proved to be a useful tool to evaluate the performance and estimate the onset gas velocity of the spouted bed.

Parenting in the Age of High-Stakes Testing: Gifted and Talented Admissions and the Meaning of Parenthood

Background/Context This work contributes to the growing body of scholarly and popular literature on middle-class parental anxiety and competition to ensure their children's academic success. Specifically, this study provides a better understanding of the measures parents will take to obtain high status gifted and talented (G&T) placements that advantage their own children at the expense of others, which is somewhat contradictory given the growing uneasiness they feel about putting their children through the testing process—and paying for test prep—that the system ultimately rewards. By analyzing the different ways in which White parents and parents of color conceive of good parenting in the era of high-stakes testing, I demonstrate the processes in our current educational system that help to produce inequities related to race, class, and G&T identification. Purpose/Objective This paper examines White parents’ beliefs about parenting as it relates to their school choice preferences in the segregated and stratified New York City school system. It also compares the parenting styles and school choices of lower income general education (Gen Ed) parents of color. It explores how parents’ social constructions of where their children belong in school are tied to their beliefs about parenting and doing what is best for their children in a highly competitive society and city. Research Design A qualitative case study was utilized to examine how a diverse group of 52 New York City parents make sense of and interact with an elementary school that offers both a segregated G&T and a Gen Ed program. The semistructured parent interview data was triangulated with school observations, a professional school-choice consultant interview, and an observation of a public school choice workshop for incoming kindergarten parents led by the consultant. Findings/Results The data show that White parents believe that paying for test prep, going through the “hassle of getting your child tested for G&T,” and receiving a high test score are symbolic of being a good parent in the system. In comparison, parents of color had different conceptions of good parenting that did not include prepping for the G&T test or getting into the G&T program, where their children would be in the minority. White parents had social networks of like-minded parents pressuring them to get into the G&T program. Black and Latino parents did not have the same G&T pressure from friends or family, nor did they view a G&T placement as giving their children extra advantages in terms of test scores or future schooling opportunities. Conclusions/Recommendations The findings suggest that the pressure for children to succeed on a single test feeds into parental anxiety and competition regarding getting their children into the high-status G&T program. Instead of trying to avoid an overly anxious parenting culture, the White advantaged parents in this setting get swept up in the test-prepping fad because everyone else is doing it and because of the competitive nature of obtaining a G&T seat. If policy officials want to attack the root of the G&T segregation problem, the city should consider phasing out district G&T programs altogether and instituting school-wide G&T magnets instead.

School Segregation vs. Desegregation in Romania. Case Study

School desegregation can be identified as an educational objective for all. The problems of school segregation relate to aspects regarding student discrimination based on various criteria: the low socioeconomic status of the family of origin, belonging to a certain ethnic group, the criterion of disability or special educational needs. The present research aims to identify good practices carried out in schools in order to combat segregation. In this regard we formulated the following objectives: the analysis of the degree of impact of anti-segregationist educational practices with regard to students (Specific objective 1); measuring the degree of effectiveness of the anti-segregationist activities implemented in the school (Specific objective 2). The units of analysis are a sample of students from schools in urban and rural areas, and a sample of their teachers. The study has made use of an intentional, structured sample, with two variables (residence of the family of origin, ethnic membership), made up of 325 students, and their teachers. The following working hypothesis has been considered: if teachers are interested in anti-segregationist education in these schools, then no discriminatory behaviors will be identified. In conclusion, the problem of segregation in the European space remains a problem, especially as we are witnessing, within such a space, cross-border migration processes involving people of different ethnicities and cultures. This aspect, in particular, attracts the attention of schools which should produce models of education carried out in a context of desegregation, and keeping the principle of equal opportunities for all in the form of social desegregation. How to cite: Anghel, G.A. (2017). School Segregation vs. Desegregation in Romania. Case Study. Revista Romaneasca pentru Educatie Multidimensionala , 9(1), 95-105. DOI: http://dx.doi.org/10.18662/rrem/2017.0901.07

Investigation on the multi-pass gas tungsten arc welded Bi-metallic combination between nickel-based superalloy and Ti-stabilized austenitic stainless steel

Abstract

Breakthrough in key science and technologies in Dendrobium catenatum industry

In view of the significant difficulties of propagation, planting and simple product in Dendrobium catenatum(D. officinale)industry development, a series of research were carried out. Genome study showed that D. catenatum is a specie of diploid with 38 chromosomes and 28 910 protein-coding genes. It was identified that specific genes accumulated in different organs at the transcriptome level. We got an insight into the gene regulation mechanism of the loss of the endospermous seed, the wide ecological adaptability and the synthesis of polysaccharides, which provided a theoretical basis for genetic engineering breeding and development and utilization of active pharmaceutical ingredients. The rapid propagation system was established for applying to industrialized production by overcoming breeding problems on seed setting and sprouting, which laid a foundation for artificial cultivation of D. catenatum. And in order to give a clear explanation of genetic variation of important economic traits, we built up the breeding system. Since special varieties of D. catenatum were bred, it helped solve the problem of trait segregation of seedling progeny and support the improvement of D. catenatum industry. The regulation of dynamic variation of target compounds, together with the mechanism of nutrient uptake, was revealed. The breakthrough of key technologies including culture substrates, light regulation and precisely collection was carried out. Several cultivation modes like facility cultivation, original ecological cultivation, cliff epiphytic cultivation, stereoscopic cultivation and potting cultivation were set up. Above all, the goal of cultivating D. catenatum as well as producing good D. catenatum will be achieved.

Towards wall functions for the prediction of solute segregation in plane front directional solidification

The present paper focuses on solute segregation occurring in directional solidification processes with sharp solid/liquid interface, like silicon crystal growth. A major difficulty for the simulation of such processes is their inherently multi-scale nature: the impurity segregation problem is controlled at the solute boundary layer scale (micrometers) while the thermal problem is ruled at the crucible scale (meters). The thickness of the solute boundary layer is controlled by the convection regime and requires a specific refinement of the mesh of numerical models. In order to improve numerical simulations, wall functions describing solute boundary layers for convecto-diffusive regimes are derived from a scaling analysis. The aim of these wall functions is to obtain segregation profiles from purely thermo-hydrodynamic simulations, which do not require solute boundary layer refinement at the solid/liquid interface. Regarding industrial applications, various stirring techniques can be used to enhance segregation, leading to fully turbulent flows in the melt. In this context, the scaling analysis is further improved by taking into account the turbulent solute transport. The solute boundary layers predicted by the analytical model are compared to those obtained by transient segregation simulations in a canonical 2D lid driven cavity configuration for validation purposes. Convective regimes ranging from laminar to fully turbulent are considered. Growth rate and molecular diffusivity influences are also investigated. Then, a procedure to predict concentration fields in the solid phase from a hydrodynamic simulation of the solidification process is proposed. This procedure is based on the analytical wall functions and on solute mass conservation. It only uses wall shear-stress profiles at the solidification front as input data. The 2D analytical concentration fields are directly compared to the results of the complete simulation of segregation in the lid driven cavity configuration. Finally, an additional output from the analytical model is also presented. We put in light the correlation between different species convecto-diffusive behaviour; we use it to propose an estimation method for the segregation parameters of various chemical species knowing segregation parameters of one specific species.

Crystallization of inorganic salt hydrates in polymeric foam for thermal energy storage application

Inorganic salt hydrates as phase change material (PCM) offers high energy storage density, low heat of combustion and relatively high thermal conductivity than organic PCMs at a reasonable cost. Moreover, these are nonflammable and also available in the large temperature range for the thermal energy storage (TES) application. However, phase segregation, supercooling and incongruent melting are the main disadvantages which confine them for TES application. In this present study, open cell polyurethane foam (PU foam) as a heterogeneous surface was introduced to mitigate the problem of phase segregation during its repeated thermal cycles. Composite (PU-PCM) having a combination of porous polyurethane foam sheet and saturated inorganic salt solution, by soaking different saturated salt solutions within pores, was prepared. Solution crystallization process was carried out to develop inorganic salt hydrate crystals within the pores from their aqueous solutions. For thermal insulation application, a model experimental setup was constructed and performance of PU-PCM composite sheet compared with the performance of dry PU foam. Various melting and freezing cycles of salt hydrates inside the porous structure were analyzed and the results are discussed.

Phase change performance assessment of salt mixtures for thermal energy storage material

Summary The phase transition performance of the CaCl2 · 6H2O–Ca(NO3)2 · 4H2O composite salt system with nucleating and thickening agents was investigated in this paper. The CaCl2 · 6H2O–Ca(NO3)2 · 4H2O composite salt system was prepared by adding Ca(NO3)2 · 4H2O (12 wt%) to CaCl2 · 6H2O. Different nucleating agents including SrCl2 · 6H2O, SrCO3, BaCl2, BaCO3, Na2B4O7 · 10H2O, H3BO3 and NH4Cl were used to address the problems of phase segregation and supercooling phenomena during the phase change process. The results show that the single nucleating agent SrCl2 · 6H2O or the mixture of nucleating agents with 2 wt% SrCl2 · 6H2O, 1 wt% BaCl2 and 0.5 wt% of thickening agent carboxyl methyl cellulose is the most suitable for this system. The latent heat remained constant at about 116 J/g before and after adding the agents. Density functional theory was used to further investigate the microstructure-related reason for the salt–water separation and supercooling phenomena. It can be deduced that the hydrogen bond is the vital factor involved during the phase transition. The aim of adding thickener was to form more hydrogen bonds which encapsulated the hydrated species and made it difficult to lose the hydrated waters. The main purpose of adding nucleating agent was to break the metastable state among microscopic species. The results of this work indicate that the CaCl2 · 6H2O–Ca(NO3)2 · 4H2O salt mixture has potential as a thermal energy storage material. Copyright © 2017 John Wiley & Sons, Ltd.

Museums, the Exhibitionary Complex and State Stability in the Victorian Era

This paper focuses on the different agents, whether public, private or voluntary, who in the Victorian Age campaigned in favour of the opening of public museums, whether national, local or municipal, and who invoked an intrication of cultural, political, social and economic rationales to muster support. In particular, these agents foregrounded the supposed capacity of museums to educate, pacify and control sections of the population considered as a threat to state stability. How were these objects of concern, i.e. the working classes, presented in the different discourses and actions relating to museums, before and after their opening? The Victorian period was one of unstable, shifting social conditions in urban areas, characterised by an increased dynamic of urbanisation, coupled with neighbourhood segregation and related problems (criminality, betting, alcohol).These changes spurred the development of the rational recreation movement, whose support for the creation of public cultural institutions is examined here. The 1851 Exhibition is focused on, insofar as it provided a quite different exhibitionary complex and context, compared to that of museums. 1851 is identified as a turning point of the Victorian Era, involving as it did a shift away from the pacifying function, until then associated with museums. In conclusion, the article examines the factors which enabled these Victorian public museums to attract large number of visits from the working classes, in a context of enduring class distinction. The article draws on primary sources and also on established theories of social control, from that of Bailey (a leisure historian) and Bennett (who drew on Foucault’s approach to apprehend the function of museums), but also on Parrat, Taylor, Kriegel, and, more recently, Jennings, Quinn, Purbrick and Woodson Boulton. The periodization, categorisation of actors, and the typology of museums proposed in this paper allows us to highlight the specific relevance of the conflicting theories regarding the role of museums.

But It Did Sink, You Understand What I Mean’: Topography of the Titanic

While post-Agreement Belfast has been undergoing an urban facelift, characterised by numerous modern property developments, tourist-centric initiatives and a general desire to eradicate the negative elements of the past with the aim of making Belfast a better place for the future, there has been a failure to address the real problems of segregation and socio-economic divide within post-conflict Belfast. This article looks at how Kai-Olaf Hesse’s Topography of the Titanic exposes some of the major flaws and lacunae in the city’s regeneration programme.

But It Did Sink, You Understand What I Mean’: Topography of the Titanic

While post-Agreement Belfast has been undergoing an urban facelift, characterised by numerous modern property developments, tourist-centric initiatives and a general desire to eradicate the negative elements of the past with the aim of making Belfast a better place for the future, there has been a failure to address the real problems of segregation and socio-economic divide within post-conflict Belfast. This article looks at how Kai-Olaf Hesse’s Topography of the Titanic exposes some of the major flaws and lacunae in the city’s regeneration programme.

Mechanical and Electrical Properties of Palladium-Coated Copper Wires with Flash Gold

Palladium-coated copper wire with flash gold (PCA) is a fine wire with an oxidation resistance layer. A new sulfidation test has been assessed in this work, confirming that PCA wires show better sulfidation corrosion resistance than either palladium-coated or bare copper wires. The sulfided surface of PCA was analyzed, along with its bonding strength and electrical properties. The metallurgic mechanism for formation of free air balls during the electric flame-off (EFO) process was identified. The flash gold layer of PCA wires can improve certain shortcomings, including: (1) efficiently promoting sulfidation corrosion resistance, (2) solving the problem of palladium segregation during the EFO process, (3) reducing the starting voltage, and (4) stabilizing the electrical resistivity of the bonding interface.

Government Policies and Ethnical Diversity Under Multiculturalism: The Study of Pohuwato Regency

This paper describes the construction of ethnic integration in Pohuwato local government policies which is supported by community under Bhinneka Tunggal Ika (Unity in Diversiy) and multiculturalism. This research employed qualitative approach with the aim of tracing and analyzing social harmony from various ethnicities existing in society and government policy Pohuwato Regency. The instruments of the study included data, facts and concepts that were relevant. This study aimed to see the problem of segregation within societies by primordial groups to solve ethnic integration in which ethnic groups are bound together. There are two regional policies (1) controlling inter-ethnic relations and constructing the model of Gorontalo community as an important element of social, cultural and political aspect which uphold openness and tolerance; and (2) using deliberative public space in order to achieve harmonious atmosphere between public (community) with the government in protecting the diversity. Therefore, it can be concluded that ethnic communities residing in Pohuwato Regency are bound to unite by the desire to improve new and better lives between immigrants and local communities. This desire becomes a symbol of unity based on mutual respect for different values to achieve the integration or unity of multicultural ethnic groups.

Molecular mechanism of the spontaneous segregation of enantiomers in liquid nanoblobs

At present, the problem of spontaneous segregation has no satisfactory theoretical description. The main difficulty is a very low probability of the spontaneous formation of a chirally pure nucleus in a racemic mixture if the enantioselectivity energy is below (10–12)kT, which does not correspond to reality. In this paper, we propose a mechanism of the enhancement of enantioselectivity in the chiral phase nucleus, which circumvents the problem of the low probability of its formation.

Can Architecture Design Solve Social Problem?

Most of architects and urban designers believe physical design gives impact on our social life. For example, a sign or landmark in the middle of a city makes people find orientation easier. In vice verse, most of social scientists believe it is social dynamic that plays role in shaping our space. How people spend their time moving from real space into cyber space is a proof that life style and IT give impact to space usage. This paper argues that interaction between physical design and social change is a two ways process. Both design aspect and social dynamic influence each other. This paper aims to examine how designing of gated community plays important role in increasing or decreasing segregation, both spatially and socially. The paper explores some architectural design principles applied in a gated community called CitraLand in west Surabaya, Indonesia, and addresses segregation between CitraLanders and outside kampung. We find CitraLand is designed openly and fully accessible for outsiders. It provides public spaces and several accessible gates and streets without walls and fences making all places inside and outside CitraLand spatially integrated. What’s interesting is it still reinforces social segregation due to its policy on prohibiting using the public park. We believe CitraLand’s planning and designing has successfully solved segregation problem spatially not socially.

Sport-based risk management: shaping motivated, responsible and self-governing citizen subjects

The Sport Programme, initiated by municipal administrators and managed by a social entrepreneur, is a Swedish sport-based intervention promoted as a response to social problems of crime and segregation in a targeted urban area. The article examines the manager and coaches’ presentation of the programme with respect to how pedagogical governing techniques are assumed to promote social change and how desirable citizen subjects are constructed for social inclusion. A variety of statements are analysed from a governmentality perspective. It is concluded that, although problems are assumed to be caused by structural segregation, the intervention targets individual change and risk management. Presumably, subjects are provided with motivational powers that are shaped by role models and applied in ‘choosing the right track’, navigating among risks and averting problems and exclusion. By representing problems as risks, avoidance is formed as an individual opportunity. This technology of individual agency is aimed at shaping motivated, responsible and self-governing citizen subjects, thus representing subjects as being responsible for their own welfare and inclusion. With respect to sport as a means of responding to social problems, the article provides reflections on and empirical accounts of the conditions of welfare provision and social work under advanced liberalism.