114 research outputs found
The Introduction of Bitcoin Futures: An Examination of Volatility and Potential Spillover Effects
Theory in Stein (1987) suggests that introducing derivative contracts, such as futures, can destabilize underlying asset prices if the contracts attract enough speculative traders. This paper examines how the introduction of Bitcoin futures influences the underlying Bitcoin market. Consistent with Stein (1987), we find that that Bitcoin\u27s volatility increases significantly during the post-introduction period. Perhaps more importantly, however, we observe significant spillover effects into related markets. For instance, in other cryptocurrencies, the increase in volatility in these markets is greater than the post-introduction increase in Bitcoin
Control of an axial flow tidal stream turbine
Tidal stream turbines have the potential to generate electricity from a renewable source that is highly predictable and non-polluting. The United Kingdomâs geographical location means that it has one of the most significant wave and tidal resources in the world. The implications of controlling horizontal axial flow, variable speed tidal stream turbines for the purpose of optimising energy capture, regulating power and reducing mechanical loads has been investigated.
The research was separated into two main areas: control of the turbine in below rated flow speeds where the objective was to maximise energy capture, and control of the turbine in high flow speeds where the aim was to regulate power, shed load and ensure the survivability of the turbine.
A control strategy that maximises the power output of a tidal stream turbine in below rated flow speeds, by allowing the rotor speed to be varied, was implemented. The performance of the control strategy was assessed in simulation and then implemented on a hardware in the loop test rig. In both cases the controller performed well and was able to maximise power output from the turbine by varying the rotor speed to maintain the optimum tip speed ratio.
Two control strategies for regulating the output power from a tidal stream turbine in high flow speeds were investigated and compared. The first strategy relies on adjusting the pitch angle of the rotor blades to regulate power and the second assumes fixed pitch rotor blades and relies on the stall characteristic of the blades to regulate power. Models of both the pitch and stall regulated turbines were developed and simulated using the commercially available software GH Tidal BladedÂź. The control system design behind both strategies was developed in Matlab. Following control implementation a comparison of each model was carried out in terms of performance under turbulent flows, loading and energy yield. Following the comparison it was concluded that the performance of the pitch regulated tidal stream turbine was superior to that of the stall regulated turbine. The research also revealed that the dynamics of each turbine model are significantly different for above rated flow speed operation. This has implications on controller design and loading experienced by each tidal stream turbin
Comovement in the Cryptocurrency Market
This study examines the comovement between 17 of the most active cryptocurrencies. We are unable to statistically reject the presence of perfect comovement between Bitcoin and six of the 16 non-Bitcoin cryptocurrencies. Consistent with the friction-based explanation for the presence of comovement, once the CBOE introduced futures contracts on Bitcoin, we find that all 16 cryptocurrencies comove with Bitcoin. These results suggest that introducing futures contracts improves the informational environment of the entire cryptocurrency market, which helps explain the unusual comovement in the cryptocurrency market
Diamondoids are not forever: microbial biotransformation of diamondoid carboxylic acids
Oil sands processâaffected waters (OSPW) contain persistent, toxic naphthenic acids (NAs), including the abundant yet littleâstudied diamondoid carboxylic acids. Therefore, we investigated the aerobic microbial biotransformation of two of the most abundant, chronically toxic and environmentally relevant diamondoid carboxylic acids: adamantaneâ1âcarboxylic acid (A1CA) and 3âethyl adamantane carboxylic acid (3EA). We inoculated into minimal salts media with diamondoid carboxylic acids as sole carbon and energy source two samples: (i) a surface water sample (designated TPW) collected from a test pit from the Mildred Lake Settling Basin and (ii) a water sample (designated 2 m) collected at a water depth of 2 m from a tailings pond. By day 33, in TPW enrichments, 71% of A1CA and 50% of 3EA was transformed, with 50% reduction in EC20 toxicity. Similar results were found for 2 m enrichments. Biotransformation of A1CA and 3EA resulted in the production of two metabolites, tentatively identified as 2âhydroxyadamantaneâ1âcarboxylic acid and 3âethyladamantaneâ2âol respectively. Accumulation of both metabolites was less than the loss of the parent compound, indicating that they would have continued to be transformed beyond 33 days and not accumulate as deadâend metabolites. There were shifts in bacterial community composition during biotransformation, with Pseudomonas species, especially P. stutzeri, dominating enrichments irrespective of the diamondoid carboxylic acid. In conclusion, we demonstrated the microbial biotransformation of two diamondoid carboxylic acids, which has potential application for their removal and detoxification from vast OSPW that are a major environmental threat
The Information Content of Option Ratios
A broad stream of research shows that information flows into underlying stock prices through the options market. For instance, prior research shows that both the PutâCall Ratio (P/C) and the Option-to-Stock Volume Ratio (O/S) predict negative future stock returns. In this paper, we compare the level of information contained in these two commonly used option volume ratios. First, we find that P/C ratios contain more predictability about future stock returns at the daily level than O/S ratios. Second, in contrast to our first set of results, O/S ratios contain more predictability about future returns at the weekly and monthly levels than P/C ratios. In fact, our tests show that while P/C ratios contain predictability about future daily returns and, to some extent, future weekly returns, the return predictability in P/C ratios is fleeting. O/S ratios, on the other hand, significantly predict negative returns at all levels: daily, weekly, and monthly. While Pan and Poteshman (2006) show that signed P/C ratios, which require proprietary data, have predictive power, we find that unsigned P/C ratios, which do not require proprietary data, also have predictive power
Gambling Preferences, Options Markets, and Volatility
Abstract This study examines whether the gambling behavior of investors affects volume and volatility in financial markets. Focusing on the options market, we find that the ratio of call option volume relative to total option volume is greatest for stocks with return distributions that resemble lotteries. Consistent with the theoretical predictions of Stein (1987), we demonstrate that gambling-motivated trading in the options market influences future spot price volatility. These results not only identify a link between lottery preferences in the stock market and the options market, but they also suggest that lottery preferences can lead to destabilized stock prices
Performance of pitch and stall regulated tidal stream turbines
Controllers for a pitch and a stall regulated horizontal axial flow, variable-speed tidal stream turbine are developed, and a performance comparison is carried out. Below rated flow speed, both turbines are operated in variable-speed mode so that the optimum tip-speed ratio is maintained. One of the turbines has variable pitch blades, which above rated speed are pitched to feather in order to regulate power. The other turbine has fixed pitch blades and uses speed-assisted stall to regulate power. The control system design behind both strategies is examined in MATLAB, with the performance under turbulent flows, loading and energy yield analysis being evaluated in GH Tidal Bladed. Both strategies provide a satisfactory performance, but the out-of-plane loads on the stall regulated turbine were higher over the entire range of operation. In addition, the dynamic characteristics of the stall regulated turbine require a more complex control design. The results suggest that the pitch regulated turbine would be a more attractive solution for turbine developers
Bacterial Community Legacy Effects Following the Agia Zoni II Oil-Spill, Greece
In September 2017 the Agia Zoni II sank in the Saronic Gulf, Greece, releasing approximately 500 tonnes of heavy fuel oil, contaminating the Salamina and Athens coastlines. Effects of the spill, and remediation efforts, on sediment microbial communities were quantified over the following 7 months. Five days post-spill, the concentration of measured hydrocarbons within surface sediments of contaminated beaches was 1,093â3,773 ÎŒg gâ1 dry sediment (91% alkanes and 9% polycyclic aromatic hydrocarbons), but measured hydrocarbons decreased rapidly after extensive clean-up operations. Bacterial genera known to contain oil-degrading species increased in abundance, including Alcanivorax, Cycloclasticus, Oleibacter, Oleiphilus, and Thalassolituus, and the species Marinobacter hydrocarbonoclasticus from approximately 0.02 to >32% (collectively) of the total bacterial community. Abundance of genera with known hydrocarbon-degraders then decreased 1 month after clean-up. However, a legacy effect was observed within the bacterial community, whereby Alcanivorax and Cycloclasticus persisted for several months after the oil spill in formerly contaminated sites. This study is the first to evaluate the effect of the Agia Zoni II oil-spill on microbial communities in an oligotrophic sea, where in situ oil-spill studies are rare. The results aid the advancement of post-spill monitoring models, which can predict the capability of environments to naturally attenuate oil
Electrical Components for Marine Renewable Energy Arrays: A Techno-Economic Review
This paper presents a review of the main electrical components that are expected to be present in marine renewable energy arrays. The review is put in context by appraising the current needs of the industry and identifying the key components required in both device and array-scale developments. For each component, electrical, mechanical and cost considerations are discussed; with quantitative data collected during the review made freely available for use by the community via an open access online repository. This data collection updates previous research and addresses gaps specific to emerging offshore technologies, such as marine and floating wind, and provides a comprehensive resource for the techno-economic assessment of offshore energy arrays
Exploring the capacity for anaerobic biodegradation of polycyclic aromatic hydrocarbons and naphthenic acids by microbes from oil-sands-process-affected waters
Both polycyclic aromatic hydrocarbons (PAHs) and naphthenic acids (NAs) are natural components of fossil fuels, but they are also widespread toxic and environmentally persistent pollutants. They are the major cause of environmental toxicity in oil-sands-process waters (OSPW). This study aimed to investigate the anaerobic biodegradation of the PAHs pyrene and 2-methylnaphthalene, and the NAs adamantane-1-carboxylic acid and a "natural" NA mixture (i.e., acid-extractable NAs from OSPW) under sulfate-reducing and methanogenic conditions by a microbial community derived from an oil sands tailings pond. Using gas-chromatography mass spectrometry (GC-MS), the rate of biodegradation was measured in relation to changes in bacterial community composition. Only 2-methylnaphthalene was significantly degraded after 260 days, with significantly more degradation under sulfate-reducing (40%) than methanogenic conditions (25%). During 2-methylnaphthalene biodegradation, a major metabolite was produced and tentatively identified as 2-naphthoic acid. Denaturing gradient gel electrophoresis (DGGE) demonstrated an increase in intensity of bands during the anaerobic biodegradation of 2-methylnaphalene, which derived from species of the genera Fusibacter, Alkaliphilus, Desulfobacterium, Variovorax, Thaurea, and Hydrogenophaga. Despite the biodegradation of 2-methylnaphthalene, this study demonstrates that, under anaerobic conditions, NAs and high-molecular-weight PAHs are the predominant molecules likely to persist in OSPW. Therefore alternative remediation strategies are required
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