Novel heating/cooling stage designed for fluid inclusion microthermometry of large stalagmite sections

Liquid–vapour homogenisation temperatures of fluid inclusions in stalagmites are used for quantitative temperature reconstructions in paleoclimate research. Specifically for this application, we have developed a novel heating/cooling stage that can be operated with large stalagmite sections of up to 17 × 35 mm2 to simplify and improve the chronological reconstruction of paleotemperature time-series. The stage is designed for use of an oil immersion objective and a high-NA condenser front lens to obtain high-resolution images for bubble radius measurements. The temperature accuracy of the stage is better than ± 0.1 °C with a precision (reproducibility) of ± 0.02 °C.

Global cooling during the Eocene Oligocene Transition

About 34 million years ago, Earth's climate shifted from a relatively ice-free world to one with glacial conditions on Antarctica characterized by substantial ice sheets. How Earth's temperature changed during this climate transition remains poorly understood, and evidence for Northern Hemisphere polar ice is controversial. Here, we report proxy records of sea surface temperatures from multiple ocean localities and show that the high-latitude temperature decrease was substantial and heterogeneous. High-latitude (45 degrees to 70 degrees in both hemispheres) temperatures before the climate transition were ~20°C and cooled an average of ~5°C. Our results, combined with ocean and ice-sheet model simulations and benthic oxygen isotope records, indicate that Northern Hemisphere glaciation was not required to accommodate the magnitude of continental ice growth during this time.

Onset of long-term cooling of Greenland near the Eocene-Oligocene boundary as revealed by branched tetraether lipids

The Eocene-Oligocene (E-O) boundary interval is considered to be one of the major transitions in Earth's climate, witnessing the first major expansion of the East Antarctic Ice Sheet. However, the extent of the associated climatic cooling, especially for high northern latitude continental landmasses, is poorly constrained. In this study we reconstruct the first mean annual air temperature (MAAT) for the Greenland landmass during the late Eocene and early Oligocene by applying a new proxy based on the distribution of branched tetraether lipids derived from soil bacteria preserved in a marine sediment core from the Greenland Basin. The temperature estimates are compared with a composite continental temperature record based on bio-climatic analysis of pollen assemblages. Both proxies reveal comparable late Eocene MAATs of ~13-15 °C and a gradual long-term cooling of ~3-5 °C starting near the E-O boundary. These data are in agreement with other MAAT reconstructions from northern midlatitude continents and suggest a general cooling of the Northern Hemisphere during the E-O transition.

Inherited structural controls on fault geometry, architecture and hydrothermal activity: an example from Grimsel Pass, Switzerland

Exhumed faults hosting hydrothermal systems provide direct insight into relationships between faulting and fluid flow, which in turn are valuable for making hydrogeological predictions in blind settings. The Grimsel Breccia Fault (Aar massif, Central Swiss Alps) is a late Neogene, exhumed dextral strike-slip fault with a maximum displacement of 25–45 m, and is associated with both fossil and active hydrothermal circulation. We mapped the fault system and modelled it in three dimensions, using the distinctive hydrothermal mineralisation as well as active thermal fluid discharge (the highest elevation documented in the Alps) to reveal the structural controls on fluid pathway extent and morphology. With progressive uplift and cooling, brittle deformation inherited the mylonitic shear zone network at Grimsel Pass; preconditioning fault geometry into segmented brittle reactivations of ductile shear zones and brittle inter-shear zone linkages. We describe ‘pipe’-like, vertically oriented fluid pathways: (1) within brittle fault linkage zones and (2) through alongstrike- restricted segments of formerly ductile shear zones reactivated by brittle deformation. In both cases, low-permeability mylonitic shear zones that escaped brittle reactivation provide important hydraulic seals. These observations show that fluid flow along brittle fault planes is not planar, but rather highly channelised into sub-vertical flow domains, with important implications for the exploration and exploitation of geothermal energy.

Near Real-Time Detection Of Pipe Bursts in Water Distribution Systems

The research work presented in the thesis describes a new methodology for the automated near real-time detection of pipe bursts in Water Distribution Systems (WDSs). The methodology analyses the pressure/flow data gathered by means of SCADA systems in order to extract useful informations that go beyond the simple and usual monitoring type activities and/or regulatory reporting , enabling the water company to proactively manage the WDSs sections. The work has an interdisciplinary nature covering AI techniques and WDSs management processes such as data collection, manipulation and analysis for event detection. Indeed, the methodology makes use of (i) Artificial Neural Network (ANN) for the short-term forecasting of future pressure/flow signal values and (ii) Rule-based Model for bursts detection at sensor and district level. The results of applying the new methodology to a District Metered Area in Emilia- Romagna’s region, Italy have also been reported in the thesis. The results gathered illustrate how the methodology is capable to detect the aforementioned failure events in fast and reliable manner. The methodology guarantees the water companies to save water, energy, money and therefore enhance them to achieve higher levels of operational efficiency, a compliance with the current regulations and, last but not least, an improvement of customer service.

Tambora 1815 as a test case for high impact volcanic eruptions: Earth system effects

The eruption of Tambora (Indonesia) in April 1815 had substantial effects on global climate and led to the ‘Year Without a Summer’ of 1816 in Europe and North America. Although a tragic event — tens of thousands of people lost their lives — the eruption also was an ‘experiment of nature’ from which science has learned until today. The aim of this study is to summarize our current understanding of the Tambora eruption and its effects on climate as expressed in early instrumental observations, climate proxies and geological evidence, climate reconstructions, and model simulations. Progress has been made with respect to our understanding of the eruption process and estimated amount of SO2 injected into the atmosphere, although large uncertainties still exist with respect to altitude and hemispheric distribution of Tambora aerosols. With respect to climate effects, the global and Northern Hemispheric cooling are well constrained by proxies whereas there is no strong signal in Southern Hemisphere proxies. Newly recovered early instrumental information for Western Europe and parts of North America, regions with particularly strong climate effects, allow Tambora’s effect on the weather systems to be addressed. Climate models respond to prescribed Tambora-like forcing with a strengthening of the wintertime stratospheric polar vortex, global cooling and a slowdown of the water cycle, weakening of the summer monsoon circulations, a strengthening of the Atlantic Meridional Overturning Circulation, and a decrease of atmospheric CO₂. Combining observations, climate proxies, and model simulations for the case of Tambora, a better understanding of climate processes has emerged.

Tropical climate and vegetation simulations during the Heinrich event 1 using an Earth System Model of Intermediate Complexity (EMIC) - the University of Victoria Earth System-Climate Model (UVic ESCM)

Abrupt climate changes from 18 to 15 thousand years before present (kyr BP) associated with Heinrich Event 1 (HE1) had a strong impact on vegetation patterns not only at high latitudes of the Northern Hemisphere, but also in the tropical regions around the Atlantic Ocean. To gain a better understanding of the linkage between high and low latitudes, we used the University of Victoria (UVic) Earth System-Climate Model (ESCM) with dynamical vegetation and land surface components to simulate four scenarios of climate-vegetation interaction: the pre-industrial era, the Last Glacial Maximum (LGM), and a Heinrich-like event with two different climate backgrounds (interglacial and glacial). We calculated mega-biomes from the plant-functional types (PFTs) generated by the model to allow for a direct comparison between model results and palynological vegetation reconstructions. Our calculated mega-biomes for the pre-industrial period and the LGM corresponded well with biome reconstructions of the modern and LGM time slices, respectively, except that our pre-industrial simulation predicted the dominance of grassland in southern Europe and our LGM simulation resulted in more forest cover in tropical and sub-tropical South America. The HE1-like simulation with a glacial climate background produced sea-surface temperature patterns and enhanced inter-hemispheric thermal gradients in accordance with the "bipolar seesaw" hypothesis. We found that the cooling of the Northern Hemisphere caused a southward shift of those PFTs that are indicative of an increased desertification and a retreat of broadleaf forests in West Africa and northern South America. The mega-biomes from our HE1 simulation agreed well with paleovegetation data from tropical Africa and northern South America. Thus, according to our model-data comparison, the reconstructed vegetation changes for the tropical regions around the Atlantic Ocean were physically consistent with the remote effects of a Heinrich event under a glacial climate background.

Results of Heinrich event 1 simulation from the University of Victoria Earth System-Climate Model (UVic ESCM) and the Community Climate System Model (CCSM3)

We investigated changes in tropical climate and vegetation cover associated with abrupt climate change during Heinrich Event 1 (HE1, ca. 17.5 ka BP) using two different global climate models: the University of Victoria Earth System-Climate Model (UVic ESCM) and the Community Climate System Model version 3 (CCSM3). Tropical South American and African pollen records suggest that the cooling of the North Atlantic Ocean during HE1 influenced the tropics through a southward shift of the rain belt. In this study, we simulated the HE1 by applying a freshwater perturbation to the North Atlantic Ocean. The resulting slowdown of the Atlantic Meridional Overturning Circulation was followed by a temperature seesaw between the Northern and Southern Hemispheres, as well as a southward shift of the tropical rain belt. The shift and the response pattern of the tropical vegetation around the Atlantic Ocean were more pronounced in the CCSM3 than in the UVic ESCM simulation. For tropical South America, opposite changes in tree and grass cover were modeled around 10° S in the CCSM3 but not in the UVic ESCM. In tropical Africa, the grass cover increased and the tree cover decreased around 15° N in the UVic ESCM and around 10° N in the CCSM3. In the CCSM3 model, the tree and grass cover in tropical Southeast Asia responded to the abrupt climate change during the HE1, which could not be found in the UVic ESCM. The biome distributions derived from both models corroborate findings from pollen records in southwestern and equatorial western Africa as well as northeastern Brazil.

A study in the application of domestic solar assisted heat pumps for heating and cooling

In the present work, the more important parameters of the heat pump system and of solar assisted heat pump systems were analysed in a quantitative way. Ideal and real Rankine cycles applied to the heat pump, with and without subcooling and superheating were studied using practical recommended values for their thermodynamics parameters. Comparative characteristics of refrigerants here analysed looking for their applicability in heat pumps for domestic heating and their effect in the performance of the system. Curves for the variation of the coefficient of performance as a function of condensing and evaporating temperatures were prepared for R12. Air, water and earth as low-grade heat sources and basic heat pump design factors for integrated heat pumps and thermal stores and for solar assisted heat pump-series, parallel and dual-systems were studied. The analysis of the relative performance of these systems demonstrated that the dual system presents advantages in domestic applications. An account of energy requirements for space and hater heating in the domestic sector in the O.K. is presented. The expected primary energy savings by using heat pumps to provide for the heating demand of the domestic sector was found to be of the order of 7%. The availability of solar energy in the U.K. climatic conditions and the characteristics of the solar radiation here studied. Tables and graphical representations in order to calculate the incident solar radiation over a tilted roof were prepared and are given in this study in section IV. In order to analyse and calculate the heating load for the system, new mathematical and graphical relations were developed in section V. A domestic space and water heating system is described and studied. It comprises three main components: a solar radiation absorber, the normal roof of a house, a split heat pump and a thermal store. A mathematical study of the heat exchange characteristics in the roof structure was done. This permits to evaluate the energy collected by the roof acting as a radiation absorber and its efficiency. An indication of the relative contributions from the three low-grade sources: ambient air, solar boost and heat loss from the house to the roof space during operation is given in section VI, together with the average seasonal performance and the energy saving for a prototype system tested at the University of Aston. The seasonal performance as found to be 2.6 and the energy savings by using the system studied 61%. A new store configuration to reduce wasted heat losses is also discussed in section VI.

Radially rotating miniature heat pipes for turbine blade cooling applications

Aerospace turboengines present a demanding challenge to many heat transfer scientists and engineers. Designers in this field are seeking the best design to transform the chemical energy of the fuel into the useful work of propulsive thrust at maximum efficiency. To this aim, aerospace turboengines must operate at very high temperatures and pressures with very little heat losses. These requirements are often in conflict with the ability to protect the turboengine blades from this hostile thermal environment. Heat pipe technology provides a potential cooling means for the structure exposed to high heat fluxes. Therefore, the objective of this dissertation is to develop a new radially rotating miniature heat pipe, which would combine the traditional air-cooling technology with the heat pipe for more effective turboengine blade cooling. ^ In this dissertation, radially rotating miniature heat pipes are analyzed and studied by employing appropriate flow and heat transfer modeling as well as experimental tests. The analytical solutions for the flows of condensate film and vapor, film thickness, and vapor temperature distribution along the heat pipe length are derived. The diffuse effects of non-condensable gases on the temperature distribution along the heat pipe length are also studied, and the analytical solutions for the temperature distributions with the diffuse effects of non-condensable gases are obtained. Extensive experimental tests on radially rotating miniature heat pipes with different influential parameters are undertaken, and various effects of these parameters on the operation of the heat pipe performance are researched. These analytical solutions are in good agreement with the experimental data. ^ The theoretical and experimental studies have proven that the radially rotating miniature heat pipe has a very large heat transfer capability and a very high effective thermal conductance that is 60–100 times higher than the thermal conductivity of copper. At the same time, the heat pipe has a simple structure and low manufacturing cost, and can withstand strong vibrations and work in a high-temperature environment. Therefore, the combination of the traditional air-cooling technology with the radially rotating miniature heat pipe is a feasible and effective cooling means for high-temperature turbine blades. ^