281 research outputs found
Data repository for ‘Predicting battery end of life from solar off-grid system field data using machine learning’
No full textThis dataset was generated by 1027 lead-acid batteries from BBOXX Ltd., each with nominal voltage 12 V (internally comprising 6 cells in series), nominal capacity 20 Ah, and attached to a 50 Wp photovoltaic panel. These systems are used for lighting, phone charging and small appliances, and are located across sub-Saharan Africa. Each battery was in use for 400-760 days. A full explanation is given in the associated paper which may be found at https://arxiv.org/abs/2107.13856
Oxford Battery Degradation Dataset 1
No full textLithium-ion (Li-ion) batteries are the most popular energy storage technology in consumer electronics and electric vehicles and are increasingly applied in stationary storage systems. Yet, concerns about safety and reliability remain major obstacles, which must be addressed in order to improve the acceptance of this technology. The gradual degradation of Li-ion cells over time lies at the heart of this problem. Time, usage and environmental conditions lead to performance deterioration and cell failures, which, in rare cases, can be catastrophic due to fires or explosions. The physical and chemical mechanisms responsible for degradation are numerous, complex and interdependent. Our understanding of degradation and failure of Li-ion cells is still very limited and more limited yet are reliable and practical methods for the detection and prediction of these phenomena.
This dataset contains the results of long term cycling of 8 lithium-ion cells in our lab in Oxford. The full details are given in the readme.txt file
Locating large-scale energy storage: spillover effects, carbon emissions, and balancing costs across Italy
No full textReaching net zero requires substantial large-scale energy storage systems (LESS) deployment. This strategy poses key challenges, including understanding how different LESS technologies compare in terms of both economic benefits and environmental impact, as well as analysing the complex interactions within and between markets when storage is deployed. To help shed light on these aspects, we investigate how LESS location, rated power, duration, and technology can affect welfare and carbon emissions in the Italian electricity system by modelling the day-ahead and the ancillary services markets. We considered lithium-ion batteries, pumped-storage hydro, and vanadium redox flow batteries. The results show that deploying LESS is always beneficial in the day-ahead market, but ancillary services costs can increase due to spillover effects because these markets run sequentially. Lithium-ion is the technology that yields the best social welfare increase. Location, rated power, and duration significantly impact carbon emissions, with changes ranging from −260 kgCO2 to 190 kgCO2 per MWh traded. These results suggest that LESS can help increase welfare and induce unintended consequences, such as spillovers across markets with a mixed effect on emissions
Data repository for 'Understanding long-term energy use in off-grid solar home systems in sub-Saharan Africa'
No full textThis dataset contains hourly load demand time-series from 1,000 off-grid solar home systems deployed across sub-Saharan Africa. These systems typically power lighting, phone charging, fans, radios, and small televisions. Each column represents one household, with hourly consumption values (Wh) recorded for 391–1232 days. Further details are provided in the associated preprint: https://arxiv.org/abs/2502.1463
Data repository for 'Multiscale coupling of surface temperature with solid diffusion in large lithium-ion pouch cells'
No full textPlease see the file readme.tx
Securities: An analysis of Howey test in the operational dynamics of virtual currency
No full textThe rise of the digital information age brought the term virtual currency. Virtual currency is a foreign concept. An online community of users create this digital money. To date, there are small and medium enterprises in the country which are using this kind of technology. As a consequence, their transactions became more efficient, and effective in delivering their goods and services to their consumers. The result of this virtual currency usage especially remittances among overseas Filipino workers (OFWs) gave rise to a regulation of the Bangko Sentral ng Pilipinas (BSP) through its issuance of Circular no. 944, Series of 2017. In the Philippine legal definition, virtual currency does not attain a precise meaning. However, resolutions from the Securities and Exchange Commission (SEC) although they do not form part of the Philippine law classified virtual currencies as securities. In particular, SEC concluded that it passed the Howey Test.1 Thus, the author proposed that virtual currency is an investment contract. In this paper, the author sought to focus on the legal and operational dynamics of virtual currencies. The author asserts that virtual currency is a security classified as investment contracts passing the Howey Test2. The 1 In re: Black Cell Technology, Inc, et. al., SEC CDO Case No. 01-18-046 2 Howey Test is a United States Supreme Court decision from SEC v. W.J. Howey Co. within the meaning of the Securities Act of 1933. This is an important case in determining the general applicability of the federal securities law. The decision was adopted by the Philippine Supreme Court in -i- 4 - incorporation of decided cases and legal principles of the Philippine Supreme Court would give the legal meaning of virtual currency in the local context. Passing the Howey Test, virtual currencies are required to be registered pursuant to Section 8 of the Securities Regulation Code. Chapter One discussed the background of the study, thesis and problem statement, and objective. Chapter Two defined terminologies related to the study. Chapter Three discussed the related literature of virtual currencies as electronic in form, and as an investment contract. Chapter Three provided for the analysis. Chapter Four discussed the conclusion. Lastly, Chapter Five recommended that virtual currency is a security under the realm of the Philippine legal context
Path Dependent Battery Degradation Dataset Part 1: Investigation of Path Dependent Degradation in Lithium-Ion Batteries : Degradation Dataset, T. Raj, D. A. Howey
No full textModels that predict battery lifetime require knowledge of the causes of degradation and operating conditions that accelerate it. Batteries experience two aging modes: calendar aging at rest and cyclic aging during the passage of current. Existing empirical aging models treat these as independent, but degradation may be sensitive to their order and periodicity – a phenomenon that has been called ‘path dependence’. This long-term dataset was collected to study the influence of path dependence in commercially available lithium-ion 18650 cells with nickel cobalt aluminium oxide (NCA) positive electrodes and graphite negative electrodes. Four groups of 3 cells each were subjected to combined load profiles comprising fixed periods of calendar and cyclic aging applied in various orders. Cells in groups 1 and 2 were exposed to one day of cycling followed by five days of calendar aging at C/2 and C/4 respectively. Cells in groups 3 and 4 were exposed to two days of cycling followed by ten days of calendar aging at C/2 and C/4 respectively. The data collected while the cells were exposed to the combined profiles as well as the reference performance tests and electrochemical impedence spectroscopy data is included in this dataset. Further information is available in the readme.txt file
Improved Analytical Model of an Outer Rotor Surface Permanent Magnet Machine for Efficiency Calculation with Thermal Effect
No full textIn this paper, an improved analytical model accounting for thermal effects in the electromagnetic field solution as well as efficiency map calculation of an outer rotor surface permanent magnet (SPM) machine is described. The study refers in particular to an in-wheel motor designed for automotive electric powertrain. This high torque and low speed application pushes the electric machine close to its thermal boundary, which necessitates estimates of winding and magnet temperatures to update the winding resistance and magnet remanence in the efficiency calculation. An electromagnetic model based on conformal mapping is used to compute the field solution in the air gap. The slotted air-gap geometry is mapped to a simpler slotless shape, where the field solution can be obtained by solving Laplace's equation for scalar potential. The canonical slottless domain solution is mapped back to the original domain and verified with finite element model (FEM) results. Closed form solutions of core loss and magnet loss are derived from the air-gap field solution. The copper loss is calculated by considering the proximity loss and skin effects. In order to estimate the winding and magnet temperatures, a thermal model is built using a lumped parameter thermal network with an improved discretization approach. The model has been validated experimentally using the end-winding and coolant temperatures. The energy consumption calculation with the New European Driving Cycle (NEDC) is performed and the benefit of having the thermal model is quantified in terms of percentage difference in the calculated energy consumptions
Climate Change, Sea-Level Rise, and the Vulnerable Cultural Heritage of Coastal New Hampshire
No full textIn this brief, author Meghan Howey examines the impact of climate change and sea-level rise on the vulnerable cultural heritage of coastal New Hampshire. Coastal New Hampshire has been identified by scientists and recognized by policy makers as an area experiencing many of the effects of climate change, including increasing temperatures and rising sea levels. The continued trajectory of such change places the seacoast region at a very high risk of coastal flooding today and of coastal land submersions within the next 50 to 100 years. Coastal New Hampshire stands to lose 14 percent of its known prehistoric and historic cultural heritage sites, including twelve sites on the National Register of Historic Places, to sea-level rise. These losses would negatively impact the region’s robust tourist economy. More than 80 known historic cemeteries are at risk of damage or complete destruction by sea-level rise. The potential damage to unknown, yet-to-be discovered burial grounds is also of concern. Communities across the region face difficult questions about what they are willing to lose and what efforts they are able and willing to make to protect vulnerable cultural heritage sites and graveyards from sea-level rise. Given the significance of these cultural heritage sites in coastal New Hampshire and the disproportionate contributions they make to the state’s revenue, these questions must addressed head-on, and continued analyses, discussions, and policy development will be important for addressing the vulnerability of the region’s cultural heritage
Comments on Howey and O'Shea's “Bear's Journey and the Study of Ritual in Archaeology”
No full textHowey and O'Shea (2006) misrepresent one of my statements twice, attributing a position to me that I have argued against for two decades: they misrepresent the way that ethnography is used in the archaeology of religion and the manner in which rock art research is conducted; and, despite their claims to the contrary, their study illustrates the importance of the identification of meaning in the archaeology of religion.</jats:p
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