Microfluidic systems for the analysis of the viscoelastic fluid flow phenomena in porous media

In this study, two microfluidic devices are proposed as simplified 1-D microfluidic analogues of a porous medium. The objectives are twofold: firstly to assess the usefulness of the microchannels to mimic the porous medium in a controlled and simplified manner, and secondly to obtain a better insight about the flow characteristics of viscoelastic fluids flowing through a packed bed. For these purposes, flow visualizations and pressure drop measurements are conducted with Newtonian and viscoelastic fluids. The 1-D microfluidic analogues of porous medium consisted of microchannels with a sequence of contractions/ expansions disposed in symmetric and asymmetric arrangements. The real porous medium is in reality, a complex combination of the two arrangements of particles simulated with the microchannels, which can be considered as limiting ideal configurations. The results show that both configurations are able to mimic well the pressure drop variation with flow rate for Newtonian fluids. However, due to the intrinsic differences in the deformation rate profiles associated with each microgeometry, the symmetric configuration is more suitable for studying the flow of viscoelastic fluids at low De values, while the asymmetric configuration provides better results at high De values. In this way, both microgeometries seem to be complementary and could be interesting tools to obtain a better insight about the flow of viscoelastic fluids through a porous medium. Such model systems could be very interesting to use in polymer-flood processes for enhanced oil recovery, for instance, as a tool for selecting the most suitable viscoelastic fluid to be used in a specific formation. The selection of the fluid properties of a detergent for cleaning oil contaminated soil, sand, and in general, any porous material, is another possible application

Single-Phase Flow of Non-Newtonian Fluids in Porous Media

The study of flow of non-Newtonian fluids in porous media is very important and serves a wide variety of practical applications in processes such as enhanced oil recovery from underground reservoirs, filtration of polymer solutions and soil remediation through the removal of liquid pollutants. These fluids occur in diverse natural and synthetic forms and can be regarded as the rule rather than the exception. They show very complex strain and time dependent behavior and may have initial yield-stress. Their common feature is that they do not obey the simple Newtonian relation of proportionality between stress and rate of deformation. Non-Newtonian fluids are generally classified into three main categories: time-independent whose strain rate solely depends on the instantaneous stress, time-dependent whose strain rate is a function of both magnitude and duration of the applied stress and viscoelastic which shows partial elastic recovery on removal of the deforming stress and usually demonstrates both time and strain dependency. In this article the key aspects of these fluids are reviewed with particular emphasis on single-phase flow through porous media. The four main approaches for describing the flow in porous media are examined and assessed. These are: continuum models, bundle of tubes models, numerical methods and pore-scale network modeling.Comment: 94 pages, 12 figures, 1 tabl

Financial Risk Management in the Private International Financial Institutions

Diplomdarba tēma ir “Finanšu risku parvaldīšana privātās starptautiskās finanšu institūcijās. Vadošais komercbanku darbības pamatprincips ir tiekšanās pēc maksimāli lielas peļņas. Pie tam, iespējamās peļņas lielums ir tieši proporcionāls riskam. Bankas darbības risks nozīmē, ka bankas faktiskā peļņa būs mazāka nekā ieplānotā, gaidāmā. Jo lielāka ir gaidāmā peļņa, jo lielāks risks. Risku ir jāvada, izmantojot dažādas metodes, kuras ļauj ar noteiktu precizitātes pakāpi prognozēt riska notikuma parādīšanās un mazināt tā sekas. Izvēlēta darba mērķis – pamatojoties uz ekonomiskās literatūras kopsavilkumu, apskatīt komercbanku finanšu riskus, to definīcijas, būtību un pārvaldīšanas metodes, kā arī izmantojot teorētisko informāciju un AS „ABLV Bank” darbības radītājus, identificēt riska lielumu un izstrādāt priekšlikumus finanšu riska ierobežošanaiThe theme of the degree work is „Financial risk management in the private international financial institutions”. The guiding principle of the commercial bank activity is the aim to get higher income.In addition, the potential income is directly proportional to the risk. Bank risk means that bank actual profit will be less that planned, expected. The higher the expected profit the higher the risk. Risk should be managed through a variety of methods, that allow precisely predict the emergence of risk and reduce it’s consequences. The aim of the degree work is to estimate the main financial risks of commercial banks, it’s definitions, essence and management methods on the basis of economic literature, using mentioned theoretical information and AS „ABLV Bank” economic activity indices to identify the magnitude of the risk and to develop proposals for the problem

Corporate Social Responsibility in the Field of Debt Collection in Latvia

Bakalaura darba tēma ir Korporatīvā sociālā atbildība parādu piedziņas jomā Latvijā. Bakalaura darba mērķis ir analizēt korporatīvās sociālās atbildības izpratni un vidi Latvijā, pētījumu koncentrējot uz korporatīvās sociālās atbildības realizācijas iespējām parādu piedziņas uzņēmumos Latvijā. Pirmajā daļā tiek analizēts korporatīvās sociālās atbildības jēdziens. Otrajā daļā tiek analizēta korporatīvās sociālās atbildības vide. Trešajā daļā tiek pētīts sabiedrības viedoklis jautājumos par KSA vidi Latvijā un KSA principiem parādu piedziņas jomā, kā arī tiek pētīts konkrēta parādu piedziņas uzņēmuma darbinieku viedoklis saistībā ar jautājumiem par KSA. Darbs sastāv no 76 lpp, 2 pielikumi, 12 attēliem. Atslēgvārdi: Korporatīvā sociālā atbildība, parādu piedziņas uzņēmumi, korporatīvās sociālās atbildības stratēģijasThe topic of the Bachelor thesis is Corporate Social Responsibility in the field of debt collection in Latvia. The aim of the Bachelor thesis is to analyse the dynamics of Corporate Social Responsibility based on the ground of theoretical sources. In the first chapter the notion of CSR, its development dynamics CSR and its influencing aspects in Europe and. In the third part the public opinion on the environment of CSR in Latvia and the principles of CSR in the field of debt collection has been explored. In addition to the public believes the opinions of the employees of particular Debt Collection Company have been investigated regarding questions about CSR. The Bachelor thesis consists of 76 pages, 2 appendices, 12 images. Keywords: Corporate Social Responsibility, Debt Collection Companies, corporate social responsibility strategies

Transitioning to university: the engineering students’ struggle

BACKGROUND As students transition to university study at undergraduate level they can experience numerous opportunities and challenges, both from a personal and academic perspective. Although each student will bring with them varying levels of mastery of the necessary generic study skills and techniques to deal with stress, making students aware of these skills and the importance of developing them is critical. Often within a first year context, these skills are assumed knowledge and are not specifically addressed. Potentially this is a large gap in engineering education affecting the transition experience of students into university and the retention of first year students who experience the effects of stress. PURPOSE The purpose of this paper is to assess the effectiveness of a first year engineering program designed and delivered to address any shortfall in generic academic skill capability and expand the students’ personal awareness as a way to achieve a more stress-free transition to university studies. APPROACH The True You program is a nine week, 15 minute block pilot program that delivers a range of topics to support engineering students in their first year, including lecture materials, student engagement activities and facilitated discussions. The program is designed to support students to further develop generic academic skills and learn techniques that allow them to connect more deeply with themselves and their body, as a way to potentially achieve a more stress-free student experience. Both a qualitative and quantitative approach has been adopted using an anonymous survey instrument as the primary tool to collect information about the student experience which is then analysed in light of the literature and the collective reflections of the presenter and observers of the program. RESULTS Almost three-quarters (73%) of the students stated the True-You Model felt personally true for them and 90% found the program useful as a first-year engineering student. A majority of students indicated resonating with the techniques aimed to support conscious presence in order to deal more effectively with stress, with ‘failing a unit’ the primary stressor. Although the sessions around academic study skills and self-care practices were deemed supportive, the real learning and adjustments to tertiary education will not necessarily be realised until the end of the first session, hence a flexible approach that supports the adaptation to university life may always be required. CONCLUSIONS There is great difficulty in the first year aligning students’ expectations to the realities of the student experience including the study workload and stresses that present along the way. Whilst programs such as the True-You Program can raise awareness and provide practical support to students on the realities of tertiary education, many will not be saved from the stresses and strains until they have endured the university experience for themselves. Survey results and student comments suggest the program was successful in providing support in a practical way for students transitioning to university. Whilst universities must ensure their expectations of students are reasonable and that the environment supports learning and student wellbeing, students have joint responsibility to do the academic work necessary to meet the demands of the degree and engage in healthy lifestyle practices that support themselves to succeed in a high stress environment