Electrode, electrocatalyst and electrolyte development for hybrid redox flow batteries

The development of new electrochemical devices and their subsequent widespread adoption alongside our energy grids is critical to support the incoming wave of renewable energy generation and the transition to net zero. Hybrid redox flow batteries are a promising alternative energy storage technology that could ultimately provide inexpensive and sustainable large scale energy storage solutions compared to their lithium-based counterparts. Technological improvements rely on improved understanding of the processes occurring in these devices. This thesis focuses on three aspects essential to all electrochemical devices – the electrode, electrocatalyst and electrolyte. First, electrochemical and tomographic imaging analyses are combined to understand the effect of electrode microstructure properties on the performance of a non-aqueous redox flow battery. With the help of a one dimensional model, mass-transfer coefficients are gathered from the experimentally determined polarisation curves and affirm the results positively linking electrode permeability to overall cell performance. Second, the synthesis and optimisation of a multifunctional, nitrogen-doped carbon based electrocatalyst is outlined. The active site of the electrocatalyst is examined using a suite of physical characterisation techniques and is shown to have intriguing versatility across the pH spectrum towards catalysing both oxygen and hydrogen fundamental reactions. This catalyst is then tested, with a variety of success, in two fuel cell devices and, alongside the electrodes tested in the first section, in a hydrogen-manganese hybrid redox flow battery. Finally, the aqueous liquid electrolyte involved in this hybrid redox flow battery is scrutinised. Two in-operando analytical techniques are developed, providing improved handles on real-time solution-phase manganese species concentration in the electrolyte. The production of solid manganese oxides significantly alters solution equilibria making the deconvolution of electrochemical and adjacent, simultaneous chemical processes complex.Open Acces

Performance Improvement of Non-Governmental Organisations through Financial Management: A Case study of Young Men's Christian Association of Ghana

Non-governmental organizations (NGOs) in Ghana have a history of being short-lived. However, Young Men's Christian Association (YMCA) Ghana, on the other hand has achieved notable success by impacting millions of lives over 50 years of working in Ghana. Apparently, this research investigates into the key financial management practices of NGOs in Ghana using the case of YMCA Ghana. The study revealed that, the quality of Financial Management staff and their responsibility are the most effective financial management indicator in YMCA Ghana amongst all the other well-functioning indicators. Nevertheless, it is evident in the study that the challenge YMCA Ghana faces in its financial management practice is irregular external audit review of financial and accounting data. Therefore, it is recommended that frequent subscription for external audit services should be established in NGOs and also, cost effective monitoring, evaluation, accountability and learning (MEAL) programme management framework should be adopted by NGOs in Ghana

Performance Improvement of Non-Governmental Organisations through Financial Management. A Case Study of Young Men's Christian Association of Ghana

Non-governmental organizations (NGOs) in Ghana have a history of being short-lived. However, Young Men's Christian Association (YMCA) Ghana, on the other hand has achieved notable success by impacting millions of lives over 50 years of working in Ghana. Apparently, this research investigates into the key financial management practices of NGOs in Ghana using the case of YMCA Ghana. The study revealed that, the quality of Financial Management staff and their responsibility is the most effective financial management indicator in YMCA Ghana amongst all the other well-functioning indicators. Nevertheless, it is evident in the study that the challenge YMCA Ghana faces in its financial management practice is irregular external audit review of financial and accounting information. Therefore, it is recommended that frequent subscription for external audit services should be established in NGOs and also, cost effective monitoring, evaluation, accountability and learning (MEAL) programme management framework should be adopted by NGOs in Ghana

Optimal effort in consumer choice : theory and experimental analysis for binary choice

This paper develops a theoretical model of optimal effort in consumer choice. The model extends previous consumer choice models in that the consumer not only chooses a product, but also decides how much effort to apply to a given choice problem. The model yields a unique optimal level of effort, which depends on the consumer's cost of effort, the expected utility gain of a correct choice, and the complexity of the choice set. We show that the relationship between effort and cost of effort is negative, whereas the relationships between effort and product utility difference and choice task complexity are undetermined. To resolve this theoretical ambiguity and to explore our model empirically, we investigate the relationships between effort and cost of effort, product utility difference and choice task complexity using data from a conjoint choice study of two-alternative consumer restaurant choices. Response time is used as a proxy for effort and consumer involvement measures capture individual differences in (relative) cost of effort and perceived complexity. Effort is explained using the (estimated) utility difference between alternatives, the number of elementary information processes (EIP's) required to solve the choice problem optimally and respondent specific cost of effort and complexity perceptions. The predictions of the theoretical model are supported by our empirical findings. Response time increases with lower cost of effort and greater perceived complexity (i.e. higher involvement). We find that across the range of choice tasks in our survey, effort increases linearly with smaller product utility differences and greater choice task complexity

Complexity and accuracy in consumer choice : the double benefits of being the consistently better brand

This study investigates the impact of choice complexity on consumer utility and choice. The authors find that for choices with up to seven alternatives and seven attributes choice accuracy is affected by three context-based complexity effects but not by task-based complexity. The results suggest that brands that are able to create products that outperform competing products and that do so consistently across multiple attributes benefit from a double bonus. Not only is their product more attractive to consumers, but the accuracy with which consumers choose the product also increases, leading to a further increase in the brand's market shar

Combining and comparing consumers' stated preference ratings and choice responses

In this study we develop and test an econometric model for combining choice and preference ratings data collected from the same set of individuals. Choice data are modeled using a multinomial logit framework, while preference data are modeled using an ordered response equation. Individual heterogeneity is allowed for via random coefficients providing a link between the choice and ratings data. Parameters are estimated by Simulated Maximum Likelihood. An application of the model to consumer yoghurt choice in The Netherlands found that ratings based preference estimates differ significantly from choice based estimates, but the correlation between random coefficients driving the two is very stron

The effect of refueling decisions and engineering constraints on the fuel management for a pressurized water reactor

Also issued as a Ph. D. thesis in the Dept. of Nuclear Engineering, 1974Work sponsored by Commonwealth Edison CompanyIncludes bibliographical references (pages 383-385)M.I.T. DSR Project no. 7210

Determinantes financieros del rendimiento de las PYME. Datos en la industria del cuero en Kenia

Small and medium-sized enterprises (SMEs) are one of the buoyant businesses in the global economy with abundant resources that have not been fully exploited. Despite several revelations on the challenges of SMEs, little to none have comprehensively captured financial factors affecting the performance of SMEs, particularly, in the Kenyan leather sector. This study explores financial factors that are affecting the performance of SMEs using the case of the leather industry sector in Kenya. The study data was collected by administering questionnaires to 300 respondents who were randomly chosen from SMEs within Kenyan leather sector. The study found that financial literacy, credit access and tax are statistically significant financial factors affecting the performances of SMEs. As a result, the study recommends that Government should increase its commitment to develop SMEs by offering favorable tax rates and tax exemptions to SMEs especially those in the leather sector of Kenya. Also, SMEs should heighten their financial literacy which will help augment their access to credit.Las pequeñas y medianas empresas (PYMES) son uno de los negocios más boyantes de la economía mundial, con abundantes recursos que no han sido explotados en su totalidad. A pesar de las diversas publicaciones sobre los retos de las PYME, casi ninguna ha captado de forma exhaustiva los factores financieros que afectan al rendimiento de las PYME, en particular, en la industria del cuero en Kenia. Al parecer, este estudio explora los factores financieros que afectan al rendimiento de las PYME utilizando el caso del sector de la industria del cuero en Kenia. Los datos del estudio se recogieron mediante la administración de cuestionarios a 300 encuestados elegidos al azar entre las PYME del sector del cuero de Kenia. El estudio concluyó que los conocimientos financieros, el acceso al crédito y los impuestos son factores financieros estadísticamente significativos que afectan a los resultados de las PYME. En consecuencia, el estudio recomienda que el Gobierno aumente su compromiso con el desarrollo de las PYME ofreciendo tipos impositivos favorables y exenciones fiscales a las PYME, especialmente a las del sector del cuero de Kenia. Además, las PYME deberían aumentar sus conocimientos financieros, lo que contribuiría a aumentar su acceso al crédito

Energy Transfer between Throats from a 10d Perspective

Strongly warped regions, also known as throats, are a common feature of the type IIB string theory landscape. If one of the throats is heated during cosmological evolution, the energy is subsequently transferred to other throats or to massless fields in the unwarped bulk of the Calabi-Yau orientifold. This energy transfer proceeds either by Hawking radiation from the black hole horizon in the heated throat or, at later times, by the decay of throat-localized Kaluza-Klein states. In both cases, we calculate in a 10d setup the energy transfer rate (respectively decay rate) as a function of the AdS scales of the throats and of their relative distance. Compared to existing results based on 5d models, we find a significant suppression of the energy transfer rates if the size of the embedding Calabi-Yau orientifold is much larger than the AdS radii of the throats. This effect can be partially compensated by a small distance between the throats. These results are relevant, e.g., for the analysis of reheating after brane inflation. Our calculation employs the dual gauge theory picture in which each throat is described by a strongly coupled 4d gauge theory, the degrees of freedom of which are localized at a certain position in the compact space.Comment: 25 pages; a comment adde

The First Definitive Binary Orbit Determined with the Hubble Space Telescope Fine Guidance Sensors: Wolf 1062 (Gliese 748)

The M dwarf binary, Wolf 1062 (Gliese 748), has been observed with the Hubble Space Telescope (HST) Fine Guidance Sensor 3 in the transfer function scan mode to determine the apparent orbit. This is the first orbit defined fully and exclusively with HST, and is the most accurate definitive orbit for any resolved, noneclipsing system. The orbital period is 2.4490 ± 0.0119 yr and the semimajor axis is 01470 ± 00007—both quantities are now known to better than 1%. Using the weighted mean of seven parallax measurements and these HST data, we find the system mass to be 0.543 ± 0.031 M⊙, where the error of 6% is due almost entirely to the parallax error. An estimated fractional mass from the infrared brightness ratio and infrared mass-luminosity relation yields a mass for the primary of 0.37 M⊙, and the secondary falls in the regime of very low mass stars, with a mass of only 0.17 M⊙