An analysis and visualization of the output mode-matching requirements for squeezing in Advanced LIGO and future gravitational wave detectors

The sensitivity of ground-based gravitational wave (GW) detectors will be improved in the future via the injection of frequency-dependent squeezed vacuum. The achievable improvement is ultimately limited by losses of the interferometer electromagnetic field that carries the GW signal. The analysis and reduction of optical loss in the GW signal chain will be critical for optimal squeezed light-enhanced interferometry. In this work we analyze a strategy for reducing output-side losses due to spatial mode mismatch between optical cavities with the use of adaptive optics. Our goal is not to design a detector from the top down, but rather to minimize losses within the current design. Accordingly, we consider actuation on optics already present and one transmissive optic to be added between the signal recycling mirror and the output mode cleaner. The results of our calculation show that adaptive mode-matching with the current Advanced LIGO design is a suitable strategy for loss reduction that provides less than 2% mean output mode-matching loss. The range of actuation required is +47 uD on SR3, +140 mD on OM1 and OM2, +50 mD on the SRM substrate, and -50 mD on the added new transmissive optic. These requirements are within the demonstrated ranges of real actuators in similar or identical configurations to the proposed implementation. We also present a novel technique that graphically illustrates the matching of interferometer modes and allows for a quantitative comparison of different combinations of actuators.Comment: Matches version accepted in PR

Essays in information economics

This thesis collects three papers which study settings of imperfect information transmission. In "Strategic Information Release on a Communication Network", we study the problem of a sender who seeds a network with information, knowing that as the information spreads, it will acquire noise due to the 'broken telephone' effect. In "Noisy Disclosure", we also study communication via a noisy channel, and analyse the disclosure problem of a sender who can send a verifiable message about the state of the world, which may be corrupted by noise before reaching a receiver. In "Reputational Incentives with Networked Customers", we study networked learning for customers in a setting in which customers can observe only the reviews written by their neighbours on a network, and a firm can engage in non-contractible effort when serving customers to increase the probability of good reviews. In the first two papers, we show that a sender looking to influence the behaviour of decision makers can attempt to overcome noise in transmission by seeding the most central receiver on a network, or by failing to disclose their private information with positive probability. In the final paper, we show that restricting the ability of customers to observe only their neighbours' reviews may be welfare improving, if doing so means a firm must exert more effort to build a good reputation. Our results have important implications for consumer welfare: for example; mandatory disclosure policies for firms may be harmful if communication is noisy, while making it easier for customers to access a firm's past reviews may mean a firm with a good reputation does not exert as much effort for customers

Fate and influence of inorganics and heteroatoms during the hydrothermal carbonisation of biomass

Hydrothermal carbonisation (HTC) is an emerging biomass pre-treatment that works by converting biomass into a coal like material, in the process overcoming some of the inherent limitations of biomass. To date, there have been limited publications looking into the fate and influence inorganics and heteroatoms have on the HTC chemistry. This is surprising given these elements are of critical importance when it comes to the fuel’s utilisation. This work sets out to understand the role and fate of key inorganics and heteroatoms during HTC, but goes on to develop a mechanistic understanding of the HTC process chemistry. This work primarily focuses on the feedstocks Miscanthus, willow, brown kelp (macroalgae) and swine manure. Additionally, this work has also looked into the processing of food waste, secondary sewage sludge, AD press cake, microalgae, municipal solid wastes and oak wood, providing a large database of samples. Reaction parameters investigated as part of this work include how temperature, retention time, particle size, pH and recycling of process waters influence product yields, energy density, combustion properties, the bio-chemical composition of the bio-coal, the process water chemistry and the retention and removal of inorganics and heteroatoms. The results show that under the correct conditions HTC can produce a fuel with a HHV ranging from 25 to 30 MJ/kg (db) and the resulting bio-coal can burn like a coal, grind like coal and can overcome many of the limitations of burning biomass in pulverised coal plant. By recycling the process waters Miscanthus can be made into a fuel with an energy density of 29 MJ/kg (db), with an energy yield of 91 % and fuel properties comparable to a high volatile sub-bituminous coal. The behaviour of the inorganics and heteroatoms during HTC appear dependent on feedstock, the feedstocks inorganic chemistry and the HTC processing conditions. Generally speaking, alkali metals, which are primarily responsible for the slagging and fouling behaviour of solid fuels, are largely removed (>80%) during HTC. Moreover, when processing at 250 °C retention of calcium and reincorporation of phosphorus occurs. The combination of reduced alkali metals and relative increase in calcium and phosphorous in the ash brings about significant improvement in the fuels slagging and fouling propensity as demonstrated by the ash fusion test. It hypothesised that any residual potassium within the fuel should form calcium potassium phosphate complexes in the ash. These complexes are thermally stable and prevents the formation of low melting temperature potassium silicates or the volatilisation of potassium chloride, further reducing slagging, fouling and corrosion beyond that expected for alkali metal leaching. This can be applied to a range of low value fuels such as green harvested Miscanthus and seaweeds. This demonstrates the technologies potential to valorise low quality feedstock and produce a direct substitute bio-coal from an expanded range of terrestrial and aquatic biomass. Recycling process water brings about an increase in bio-coal energy density, energy yield and produces a fuel with more coal-like properties. It is hypothesised that the recycled process waters contain organic acids that hydrolyse the hemicellulose and cellulose to furfural like compounds at a lower temperature and increase saccharide concentrations within the process water at lower temperatures. The increased saccharide concentrations favour aromatization and repolymerisation, which better enables the decomposition products to undergo polymerisation and form the bio-coal before the increasing process temperature brings about their further degradation to organic acids. Once degraded to organic acids these acids appear to only undergo limited reincorporation into the bio-coal, but do appear to play a role in the demineralisation of the fuel. Based on this it is proposed that the slow heating rates followed by an hour retention time is favourable to overcome kinetic limitations otherwise imposed by faster heating rates and shorter retention times. The heteroatom oxygen plays a critical role in the reactions involved in HTC. The energy densification of the bio-coal is largely due to the deoxygenation of the fuel. Removal of this oxygen forms unsaturated compounds that polymerise quickly, and intermolecular dehydration results in polymerisation, condensation and aromatisation of these fragments. Oxygen is also critical in repolymerisation, with aromatic structures initially chemisorbed though reactive oxygen functionalities that dehydrate to form stable oxygen bonds linking a polymeric matrix of cyclic aromatic carbon rings. The retention of calcium also suggests it may play catalytic role in the repolymerisation process with the literature supporting this. There is however evidence that at high calcium concentrations, calcium in the process water can have an adverse effect on carbonisation, binding to surface oxygen functional groups on the biomass feedstock and preventing hydrolysis and decomposition of the feedstock

A2_1 Disaster Area

This report explores the volume, crowd placement and energy requirements of the plutonium rock band Disaster Area featured in Douglas Adams' second novel. The band was found to produce a loudness of 304 dB 1 m away from the speaker. This gave an estimate of 2.64*10^20 kg of plutonium undergoing fission in order to allow the two hour concert to perform at this noise level

A2_6 Pokémon: Let's Analyse, Darmanitan!

In this paper, the feasibility of the statement made within the "Pokedex" about the Pokémon"Darmanitan" that it can "destroy a dump truck with one punch" is explored. It was found thatit would require ~47,200 Darmanitans to produce the 1.04*10^11 J of energy needed to vaporise the dump truck entirely, although the denition of the word "destroy" is still up for debate

A2_3 Mission: Incruiseable

This paper considers the feasibility of Tom Cruise holding onto an airbus military A400m duringtake-off in a scene in the film Mission Impossible: Rogue Nation. Comparing the required forcefor Tom Cruise to remain holding onto the aeroplane to the force exerted by the deadlift Guinness World Record holder, Eddie Hall, shows that Tom Cruise would experience 3230 - 6370 N depending on his velocity and posture. Eddie Hall deadlifted 4910 N, making Tom Cruise's stunt a Mission: Impossible

A2_4 Batman's Really Big Microwave

In the lm Batman Begins (2005) an evil organisation (the League of Shadows) successfully  attempt to retrieve an experimental microwave emitter from Wayne Enterprises. This emitter is said to be used to vapourise large bodies of water using only microwaves, and the League of Shadows plan on vapourising Gotham's water supply. Here we discuss the energy and power required vapourise Gotham's water supply; 1.18 petajoules and 13.7 gigawatts respectively, as well as the isotropic electric and magnetic elds produced; 3.96*10^9 NC^-1 and 13.1 T respectively

Hydrothermal liquefaction of organic waste streams on a continuous pilot scale reactor

Hydrothermal liquefaction (HTL) is a promising technology for biofuel production and treatment of organic wastes and biomass. Due to the wet nature of the process where biomass is heated in an aqueous slurry at 350°C and 200 bar, wet biomass and wet wastes are particularly suited for the process. The current study investigates the utilization of wastewater treatment sludges and other organic wastes for the production of sustainable petroleum replacement products. The work has been carried out on a pilot scale continuous hydrothermal liquefaction reactor with a novel oscillating flow system and heat exchanger. The influence of these are discussed in terms of heat recovery and operability of the plant. The reactor was run at 50 L/h with maximum solids loadings of ~25% and short residence times of80% was accomplished, leading to an energy efficient process. During operation of the HTL system, approximately 5 units of energy are created in the form of bio-crude for every unit of energy invested for heating and pumping the slurry (EROI\u3e5). We present and discuss the results of processing diverse samples ranging from high ash (sewage sludge), lignocellulosics (miscanthus) and manure to microalgae. The potential of mixing different waste biomasses such as sludge and lignocellulosics, plastics and lignocellulosics is explored during this research and synergistic effects on bio-crude yields and fuel quality are observed, leading to higher carbon and energy recoveries. Water phase recycling of the HTL process water was employed during the liquefaction of pine where a significant increase in bio-crude yields, energy recovery and energy return on investment could be achieved. Initial results on bio-crude upgrading via catalytic hydrotreatment are also presented, demonstrating the feasibility of the HTL process as a viable pathway towards drop in replacement fuels. The current presentation gives a realistic insight into the processing of diverse biomass feedstocks at pilot scale, showing the potential of the technology while areas for future development and bottlenecks are highlighted