Effect in ewes of oestrogen priming and GnRH on LH release and luteal function during early lactation in spring

No Abstrac

Investigation into discontinuous low temperature waste heat utilisation from a renewable power plant in rural India for absorption refrigeration

This research focusses on utilising low temperature waste heat from a rural renewable power plant for absorption refrigeration. It forms part of a collaborative "Bridging the Urban Rural Divide" (BURD) research group across the United Kingdom and India investigating rural sustainable development through the provision of renewable electricity. The group is tasked with improving the educational environment and healthcare of a 45 household community (which is part of a larger village) in West Bengal, India. Working in collaboration with the Indian Institute of Technology Bombay as part of this thesis, a projected daily electrical demand for the community of 55 kW∙h per day was calculated, providing: lighting, fans and an electrical device charging station. To allow in excess of the daily electrical demand as well as for system ancillaries at 12 kW∙h, solar trackers at 14 kW∙h and 7 kW∙h for hydrogen production, a power plant producing 90 kW∙h was specified. This included daily electricity production of 70 kW∙h during the daytime from solar via a 10 kW concentrated photovoltaic (CPV) system and 20 kW∙h in the evening from a 5 kW biogas and hydrogen internal combustion engine electrical generator (genset). The biogas is produced from anaerobic digestion of food waste and aquatic weeds, and the hydrogen is produced from the electrolysis of water in an electrolyser powered by excess solar power. An energy and exergy analysis identified the daily quantity and quality of recoverable waste heat sources at 25°C. These are the CPV with an energetic value of 109 kW∙h and an exergetic value of 32 kW∙h at 60°C and the genset radiator with an energetic value of 32 kW∙h and an exergetic value of 5 kW∙h at 80°C. The exhaust heat from the genset has been allocated for other uses and, though calculated, is outside the scope of this research. The thesis then focusses on using these low temperature waste heat sources for absorption refrigeration. The working fluids selected are acetone and zinc bromide as these had been proven in the literature to operate at temperatures below those of the expected waste heat sources without the need for rectification (the process of separating two fluid vapours from each other). Due to the local climate with high ambient temperatures, averaging 24°C to 35°C, and the relatively low waste heat source temperatures, a number of configurations of absorption refrigerator were investigated to achieve lower, and therefore more versatile, evaporator temperatures. Some of these involve utilising some of the cooling produced from either or both of the heat sources to cool the absorber and condenser. The findings were that the most energy effective way of providing low evaporator temperatures was to use a small (2%) difference in weak and strong solution concentrations and not use a proportion of the cooling generated for the absorber or condenser. By operating two independent refrigerators powered by each heat source independently, the solution concentrations could be optimised to provide the lowest possible evaporator temperatures at a given ambient temperature. At the 25°C reference ambient temperature used for the energy and exergy analysis, the CPV waste heat can provide 33.4 kW∙h of continuous cooling per day at 6°C and the genset radiator 6.3 kW∙h at 0°C. This cooling energy collectively is sufficient to replace 12.7 kW∙h of electricity that would have been used to power a vapour compression refrigerator to provide the same amount of cooling, which is equal to 22% of the electrical power provided to the village. The genset waste heat source used for absorption refrigeration can provide cooling for food and medicine storage equivalent to 6 to 8 domestic refrigerators. The CPV waste heat source can provide space cooling for a room in a health centre for 6 to 9 hours per day. The investigations within this thesis highlighted the need for intelligent control systems to optimise the availability and temperatures of the refrigerators during unfavourable ambient conditions

Investigation into discontinuous low temperature waste heat utilisation from a renewable power plant in rural India for absorption refrigeration

This research focusses on utilising low temperature waste heat from a rural renewable power plant for absorption refrigeration. It forms part of a collaborative "Bridging the Urban Rural Divide" (BURD) research group across the United Kingdom and India investigating rural sustainable development through the provision of renewable electricity. The group is tasked with improving the educational environment and healthcare of a 45 household community (which is part of a larger village) in West Bengal, India. Working in collaboration with the Indian Institute of Technology Bombay as part of this thesis, a projected daily electrical demand for the community of 55 kW∙h per day was calculated, providing: lighting, fans and an electrical device charging station. To allow in excess of the daily electrical demand as well as for system ancillaries at 12 kW∙h, solar trackers at 14 kW∙h and 7 kW∙h for hydrogen production, a power plant producing 90 kW∙h was specified. This included daily electricity production of 70 kW∙h during the daytime from solar via a 10 kW concentrated photovoltaic (CPV) system and 20 kW∙h in the evening from a 5 kW biogas and hydrogen internal combustion engine electrical generator (genset). The biogas is produced from anaerobic digestion of food waste and aquatic weeds, and the hydrogen is produced from the electrolysis of water in an electrolyser powered by excess solar power. An energy and exergy analysis identified the daily quantity and quality of recoverable waste heat sources at 25°C. These are the CPV with an energetic value of 109 kW∙h and an exergetic value of 32 kW∙h at 60°C and the genset radiator with an energetic value of 32 kW∙h and an exergetic value of 5 kW∙h at 80°C. The exhaust heat from the genset has been allocated for other uses and, though calculated, is outside the scope of this research. The thesis then focusses on using these low temperature waste heat sources for absorption refrigeration. The working fluids selected are acetone and zinc bromide as these had been proven in the literature to operate at temperatures below those of the expected waste heat sources without the need for rectification (the process of separating two fluid vapours from each other). Due to the local climate with high ambient temperatures, averaging 24°C to 35°C, and the relatively low waste heat source temperatures, a number of configurations of absorption refrigerator were investigated to achieve lower, and therefore more versatile, evaporator temperatures. Some of these involve utilising some of the cooling produced from either or both of the heat sources to cool the absorber and condenser. The findings were that the most energy effective way of providing low evaporator temperatures was to use a small (2%) difference in weak and strong solution concentrations and not use a proportion of the cooling generated for the absorber or condenser. By operating two independent refrigerators powered by each heat source independently, the solution concentrations could be optimised to provide the lowest possible evaporator temperatures at a given ambient temperature. At the 25°C reference ambient temperature used for the energy and exergy analysis, the CPV waste heat can provide 33.4 kW∙h of continuous cooling per day at 6°C and the genset radiator 6.3 kW∙h at 0°C. This cooling energy collectively is sufficient to replace 12.7 kW∙h of electricity that would have been used to power a vapour compression refrigerator to provide the same amount of cooling, which is equal to 22% of the electrical power provided to the village. The genset waste heat source used for absorption refrigeration can provide cooling for food and medicine storage equivalent to 6 to 8 domestic refrigerators. The CPV waste heat source can provide space cooling for a room in a health centre for 6 to 9 hours per day. The investigations within this thesis highlighted the need for intelligent control systems to optimise the availability and temperatures of the refrigerators during unfavourable ambient conditions

UK Geoenergy Observatories, Glasgow environmental baseline soil chemistry dataset

This report describes the environmental baseline topsoil chemistry dataset collected in February-March 2018 (03-18) as part of the United Kingdom Geoenergy Observatories (UKGEOS) project. Ninety, samples were collected from the shallow coal-mine Glasgow Geothermal Energy Research Field Site (GGERFS). The report accompanies the GGERFS Soil Chemistry03-18 dataset. It provides valuable information on soil chemistry prior to installation of the GGERFS-facility boreholes, against which any future change during the development/ running of the facility can be assessed. This information is necessary to help understand and de-risk similar shallow geothermal schemes in the future, provide public reassurance, and inform sustainable energy policy

Variational Field Theoretic Approach to Relativistic Scattering

Nonperturbative polaron variational methods are applied, within the so-called particle or worldline representation of relativistic field theory, to study scattering in the context of the scalar Wick - Cutkosky model. Important features of the variational calculation are that it is a controlled approximation scheme valid for arbitrary coupling strengths, the Green functions have all the cuts and poles expected for the exact result at any order in perturbation theory and that the variational parameters are simultaneously sensitive to the infrared as well as the ultraviolet behaviour of the theory. We generalize the previously used quadratic trial action by allowing more freedom for off-shell propagation without a change in the on-shell variational equations and evaluate the scattering amplitude at first order in the variational scheme. Particular attention is paid to the $s$-channel scattering near threshold because here non-perturbative effects can be large. We check the unitarity of a our numerical calculation and find it greatly improved compared to perturbation theory and to the zeroth order variational results.Comment: 26 pages, Latex, 5 postscript figures embedded with epsf, submitted to Nucl. Phys.

The Magnetic Field of the Solar Corona from Pulsar Observations

We present a novel experiment with the capacity to independently measure both the electron density and the magnetic field of the solar corona. We achieve this through measurement of the excess Faraday rotation due to propagation of the polarised emission from a number of pulsars through the magnetic field of the solar corona. This method yields independent measures of the integrated electron density, via dispersion of the pulsed signal and the magnetic field, via the amount of Faraday rotation. In principle this allows the determination of the integrated magnetic field through the solar corona along many lines of sight without any assumptions regarding the electron density distribution. We present a detection of an increase in the rotation measure of the pulsar J1801$-$2304 of approximately 160 \rad at an elongation of 0.95$^\circ$ from the centre of the solar disk. This corresponds to a lower limit of the magnetic field strength along this line of sight of $> 393\mu\mathrm{G}$. The lack of precision in the integrated electron density measurement restricts this result to a limit, but application of coronal plasma models can further constrain this to approximately 20mG, along a path passing 2.5 solar radii from the solar limb. Which is consistent with predictions obtained using extensions to the Source Surface models published by Wilcox Solar ObservatoryComment: 16 pages, 4 figures (1 colour): Submitted to Solar Physic

Rotation measure variations for 20 millisecond pulsars

We report on variations in the mean position angle of the 20 millisecond pulsars being observed as part of the Parkes Pulsar Timing Array (PPTA) project. It is found that the observed variations are dominated by changes in the Faraday rotation occurring in the Earth's ionosphere. Two ionospheric models are used to correct for the ionospheric contribution and it is found that one based on the International Reference Ionosphere gave the best results. Little or no significant long-term variation in interstellar RM was found with limits typically about 0.1 rad m$^{-2}$ yr$^{-1}$ in absolute value. In a few cases, apparently significant RM variations over timescales of a few 100 days or more were seen. These are unlikely to be due to localised magnetised regions crossing the line of sight since the implied magnetic fields are too high. Most probably they are statistical fluctuations due to random spatial and temporal variations in the interstellar electron density and magnetic field along the line of sight.Comment: Accepted for publication in Astrophysics & Space Scienc

Effect of Parametric Resonances on the Bunched-beam Dilution Mechanism

This research was sponsored by the National Science Foundation Grant NSF PHY-931478

Misfit-Dislocation-Mediated Heteroepitaxial Island Diffusion

Scanning tunneling microscopy combined with molecular dynamics simulations reveal a dislocation-mediated island diffusion mechanism for Cu on Ag(111), a highly mismatched system. Cluster motion is tracked with atomic precision at multiple temperatures and diffusion barriers and prefactors are determined from direct measurements of hop rates. The non-monotonic size dependence of the diffusion barrier is in good agreement with simulations and can lead to enhanced mass transport upon coarsening, in surprising contrast to the traditional island diffusion models where diffusivity reduces with cluster size