A macroscopic particle modelling approach for non-isothermal solid-gas and solid-liquid flows through porous media

© 2019 Elsevier Ltd The complexity of multiphase flows in many engineering systems such as heat exchangers signify the need to develop new and advanced numerical models to analyse the interactions the working fluid and unwanted solid foulants. Fouling is present in a myriad of industrial and domestic processes and it has a negative impact on the economy and the environment. The mechanisms that govern non-isothermal solid-fluid flow through porous metal foam heat exchangers are complex and poorly understood. In this research, a coupled finite volume method (FVM) and macroscopic particle model (MPM) is developed and implemented in ANSYS Fluent to examine the transient evolution of a non-isothermal multiphase solid-fluid flow and the interaction between coupled interactions of solid particles, fluid, and porous media. The maximum particle temperature is dependent on the fluid and solid particle thermo-physical properties in addition to the temperature of the cylindrical ligaments of the porous media. The present results show that the smallest solid particles reach the highest temperatures in the porous heat exchanger and at low inlet velocities, the highest particle temperatures are realized. The results pertaining to maximum particle temperatures are prevalent in many industrial processes and acquiring knowledge of the maximum particle temperature serves as a steppingstone for comprehending complex multiphase solid-fluid flows such as the cohesiveness between the particles and the particle adhesion with the walls. The results of these studies could potentially be used in the future to optimize metal foam heat exchanger designs

Of Unity and Disunity in-between: The post/colonial ‘unhomely’ in the works and lives of Jean Rhys and Hella S. Haasse

The Creole authors Jean Rhys – born on Dominica in the former British West Indies – and Hella S. Haase – from the former Dutch East Indies, now Indonesia – challenge the idea of temporally unified colonial pasts as neatly preceding the postcolonial present. They do so by blending past and present in works on decolonisation published in the UK and the Netherlands. The real-life events of the authors’ colonial repatriation further stress that colonial unity is a construction. Within the colonial system, Rhys’s and Haasse’s biographical movements from the colonies to the European metropolises London and Amsterdam are considered re-turns to familiar motherlands (re-patriation). Yet Haasse and Rhys illustrate the complexities attached to these so-called ‘returns’ by staging and creatively appropriating them in their novels, showing a temporal and spatial disunity that proves to be inherent to both colonialism and post/colonialism

Tooth colour of Hong Kong people - their satisfaction and preference

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Genetic epidemiology of SARS-CoV-2 transmission in renal dialysis units - a high risk community-hospital interface

OBJECTIVES: Patients requiring haemodialysis are at increased risk of serious illness with SARS-CoV-2 infection. To improve the understanding of transmission risks in six Scottish renal dialysis units, we utilised the rapid whole-genome sequencing data generated by the COG-UK consortium. METHODS: We combined geographical, temporal and genomic sequence data from the community and hospital to estimate the probability of infection originating from within the dialysis unit, the hospital or the community using Bayesian statistical modelling and compared these results to the details of epidemiological investigations. RESULTS: Of 671 patients, 60 (8.9%) became infected with SARS-CoV-2, of whom 16 (27%) died. Within-unit and community transmission were both evident and an instance of transmission from the wider hospital setting was also demonstrated. CONCLUSIONS: Near-real-time SARS-CoV-2 sequencing data can facilitate tailored infection prevention and control measures, which can be targeted at reducing risk in these settings

Promoting the developmental social welfare approach in Zimbabwe: Challenges and prospects

The study was prompted by the on - going discourse on the appropriateness of existing social welfare delivery mechanisms in the Third World which, over time, have tended to be informed by the modernization approach. The prevailing view, particularly among academics and practitioners in Africa, is essentially that the continent ought to promote the developmental rather than the remedial approach to social work, in order to more effectively address the challenges faced. Zimbabwe is one of the countries that seem to have heeded this call. The study therefore sought to establish the extent to which Zimbabwe is promoting the developmental approach to social welfare provision, with special focus on the public assistance scheme. Beneficiaries of public assistance through the Department of Social Services were targeted and key informants were interviewed. A key finding of the study was that the public assistance scheme in Zimbabwe has remained essentially remedial, with only limited attempts made towards initiatives that facilitate a developmental thrust (i.e. self reliance). It emerged from the study findings that at the policy level, the thrust of the Department of Social Services (DSS) is to implement both remedial and developmental approaches to social work, while on the ground only a few of the activities of the DSS could be regarded as developmental in nature. The reason given for this anomaly was mainly scarcity of resources. The study revealed that while developmental social work was preferred (especially by the professional social workers), remedial social work is likely to remain a predominant feature particularly because of lack of a conducive environment that would enable the majority of the Department of Social Services clients to move towards self-reliance

Two- and four-way coupling of cohesive poly-disperse particulate foulants on a metal foam fibre immersed in quiescent fluid

© 2017 Elsevier Ltd The ubiquity and complexity of the unsteadiness of fouling and multiphase flows in various engineering systems signify the need to develop advanced numerical methods to study the underlying phenomena of two-phase particle-laden fluid flows in heat exchanger systems such as, compact electronics cooling (i.e. heat sinks) and HVAC&R systems. Fouling is omnipresent in many industries such as power generation, chemical, petroleum, among others. The mechanisms governing fouling coupled with multiphase foulant-laden fluid flow in porous heat exchangers, such as metal foams, are very complex and poorly understood. This investigation forms the basis for addressing the implications of fouling for a myriad of industrial processes. This study will discuss the development of a coupled finite volume method and discrete element method (FVM-DEM) numerical framework to investigate the mechanisms governing particulate fouling in an idealized metal foam heat exchanger. This study resolves four-way and two-way coupled interactions based on poly-disperse cohesive foulants in fluid-saturated foam. The significance stems from the inclusion of cohesiveness between particle-particle and particle-wall contacts which play a decisive role in the foulant aggregation process prevalent in particles with a diameter smaller than 50 μm. The present results show that the cohesive foulants exhibit strong tendency to aggregate with time and form chain-like projections. A rigid aggregate stack is formed which alters the fluid velocity of the fluid-filled foam. Quantitative analysis of the foulant count and time-averaged aggregate count is discussed. The presented results and the numerical framework could potentially be used to optimize heat exchanger designs by considering operating conditions and foam morphology (i.e. pore diameter, ligament thickness, porosity) that is most susceptible to particulate fouling

‘For I know that house where I will be not belonging’ Nostalgic processes in the post/colonial work of Jean Rhys and Hella S. Haasse

This thesis takes as its starting point the idea that the postcolonial is always in some way colonial and belated. It combines theories from Homi K. Bhabha and Rosi Braidotti, arguing that close readings of postcolonial texts should attentively investigate political and personal interconnections with the past, present and future. The thesis provides close readings of novels by Jean Rhys (1890-1979) and Hella S. Haasse (1918-2011). Both authors were born into colonial families in former colonies: Rhys in the former British West Indies; Haasse in the Dutch East Indies (now: Indonesia). They moved to Europe over the period of decolonisation. The close readings focus on critical nostalgic processes in Rhys’s and Haasse’s work, as published in the U.K and the Netherlands. Critical nostalgic processes draw attention to the authors’ insights into colonialist strategies, and connect such insights to contemporary politics in the U.K. and the Netherlands. The thesis further explores nostalgic perceptions of Rhys’s and Haasse’s work in contemporary newspaper reception, thus providing an overview of attitudes to cultural expressions of loss of the colonies at time of publication in the U.K. and the Netherlands, providing contemporary context to the authors’ critical insights. Rhys’s and Haasse’s novels demonstrate their awareness of violence done by colonial politics on a personal level. Both authors use themes of friendship and belonging to highlight the ambivalent split in colonialism. They foreground the workings of colonialist discourses and show limitations to the Self/Other dichotomy. Critical nostalgic processes thus shed new lights on violent histories of colonialism. The close readings demonstrate that Haasse’s and Rhys’s postcolonial imaginations enable ethical engagements with violent colonial pasts. As such, literature and imaginations of colonial history can provide alternatives to rigid identity politics in the postcolonial present, moving towards a truly post colonial future

An object-oriented prototyping tool for automated manufacturing systems

System prototyping is essential in the development of automated manufacturing systems (AMSs), and the value of prototyping depends largely on the effectiveness of the prototyping tool to represent a system design and also the prototyping results. This paper presents a windows-based prototyping tool that adopts a frame-based representation approach to build a prototype from an object-oriented system design specification. The tool provides a platform capable of executing the prototype under different constraints and operating conditions, and of presenting the prototyping results to facilitate the study of the behaviour of the AMS. Properties, such as the total cycle time, resource utilization, potential conflicts, errors in design, and abnormal behaviours, can be readily derived. The tool's effectiveness is illustrated by prototyping a flexible manufacturing system, and examining the results obtained. Indeed, the prototyping tool proposed in this paper is shown to provide a convenient means for the design of AMSs.link_to_subscribed_fulltex