scholarly journals Characterising thermal water circulation in fractured bedrock using a multidisciplinary approach: a case study of St. Gorman’s Well, Ireland

2021 ◽  
Author(s):  
Sarah Blake ◽  
Tiernan Henry ◽  
John Paul Moore ◽  
John Murray ◽  
Joan Campanyà ◽  
...  
Keyword(s):  
Multidisciplinary Approach ◽  
Variable Temperature ◽  
Time Lapse ◽  
Thermal Spring ◽  
Maximum Temperature ◽  
Thermal Waters ◽  
Circulation System ◽  
Hydrothermal Circulation ◽  
Hydrochemical Analysis ◽  
3D Audio

AbstractA hydrogeological conceptual model of the source, circulation pathways and temporal variation of a low-enthalpy thermal spring in a fractured limestone setting is derived from a multidisciplinary approach. St. Gorman’s Well is a thermal spring in east-central Ireland with a complex and variable temperature profile (maximum of 21.8 °C). Geophysical data from a three-dimensional(3D)audio-magnetotelluric(AMT) survey are combined with time-lapse hydrogeological data and information from a previously published hydrochemical analysis to investigate the operation of this intriguing hydrothermal system. Hydrochemical analysis and time-lapse measurements suggest that the thermal waters flow within the fractured limestones of the Carboniferous Dublin Basin at all times but display variability in discharge and temperature. The 3D electrical resistivity model of the subsurface revealed two prominent structures: (1) a NW-aligned faulted contact between two limestone lithologies; and (2) a dissolutionally enhanced, N-aligned, fault of probable Cenozoic age. The intersection of these two structures, which has allowed for karstification of the limestone bedrock, has created conduits facilitating the operation of relatively deep hydrothermal circulation (likely estimated depths between 240 and 1,000 m) within the limestone succession of the Dublin Basin. The results of this study support a hypothesis that the maximum temperature and simultaneous increased discharge observed at St. Gorman’s Well each winter is the result of rapid infiltration, heating and recirculation of meteoric waters within a structurally controlled hydrothermal circulation system.

Design and Optimization of a Composite Heat Spreader to Improve the Thermal Management of a 3D Integrated Circuit

2021 ◽  
Author(s):  
Andisheh Tavakoli ◽  
Kambiz Vafai
Keyword(s):  
Thermal Conductivity ◽  
Heat Sink ◽  
Variable Temperature ◽  
Heat Removal ◽  
High Conductivity ◽  
High Thermal Conductivity ◽  
Maximum Temperature ◽  
Optimal Distribution ◽  
Heat Spreader ◽  
The Impact

Abstract The present study analyzes the optimal distribution of a limited amount of high thermal conductivity material to enhance the heat removal of circular 3D integrated circuits, IC. The structure of the heat spreader is designed as a composite of high thermal conductivity (Boron Arsenide) and moderate thermal conductivity (copper) materials. The volume ratio of high-conductivity inserts to the total volume of the spreader is set at a fixed pertinent ratio. Two different boundary conditions of constant and variable temperature are considered for the heat sink. To examine the impact of adding high-conductivity inserts on the cooling performance of the heat spreader, various patterns of the single and double ring inserts are studied. A parametric study is performed to find the optimal location of the rings. Moreover, the optimal distribution of the high-conductivity material between the inner and outer rings is found. The results show that for the optimal conditions, the maximum temperature of the 3D IC is reduced up to 10%; while the size of the heat sink, and heat spreader can be diminished by as much as 200%.

Signal emission and signal propagation during early aggregation in Dictyostelium discoideum

1976 ◽  
Vol 22 (3) ◽  
pp. 645-656
Author(s):  
J.D. Gross ◽  
M.J. Peacey ◽  
D.J. Trevan
Keyword(s):  
Dictyostelium Discoideum ◽  
Early Phase ◽  
Variable Temperature ◽  
Spiral Wave ◽  
Cumulative Effect ◽  
Signal Propagation ◽  
Time Lapse ◽  
Period Length ◽  
Individual Wave ◽  
Complete Circuit

Waves of chemotactic movement during the early phase of aggregation in Dictyostelium discoideum are of 2 kinds, concentric waves produced by cells that emit cyclic AMP signals spontaneously, and spirals generated by excitations relayed continuously around loops of excitable cells. The period of a spiral wave is the time taken for the excitation to make one complete circuit of the pacemaker loop. We have compared signal emission from the 2 types of source in time-lapse films made at a variety of temperatures. Our results show that spiral waves have a characteristic period length throughout most if not all of the early phase of aggregation, and that the period of concentric waves is generally longer and more variable. Temperature has a pronounced effect on period length and a lesser effect on propagation velocity. We find that each individual wave is propagated at constant velocity over distances of 1–2 cm but that the velocity of successive waves declines. This decline probably reflects some cumulative effect of the chemotactic excitations on the excitable properties of the aggregating cells.

scholarly journals The groundwater flow system of Terme Alte (Alto Reno Terme, Bologna, Italy)

2020 ◽  
Author(s):  
Alessandro Gargini ◽  
Alessandro Stefani ◽  
Stefano Vannini
Keyword(s):  
Chemical Properties ◽  
Hydrological Regime ◽  
Past Research ◽  
Mineral Deposit ◽  
Thermal Waters ◽  
Circulation System ◽  
Left Bank ◽  
Aquifer System ◽  
Hydrogeological Parameters ◽  
Groundwater Circulation

The thermal field of Porretta Terme, located in the Alto Reno Terme municipality (Bologna), has always raised interest for its peculiar waters since ancient times. Indeed, the use of the springs dates back to the I-II century A.D. and perhaps even in the Etruscan period. Porretta’s thermal tradition has developed over the centuries. First regulation, issued in 1936, allowed to cultivate the mineral deposit and its natural gas in a 740 000 acres wide land. The thermal waters, a public good, are indeed ruled by specific laws which control their use through a grant where the Public Authority makes the licensee, usually a private, follow a series of accomplishments aimed at not damaging the quantitative and qualitative characteristics (R.D. July 29, 1927 n. 1443). Fourteen thermo-mineral springs out of the nineteen located in the given land are currently exploited. They are divided into two groups, which differentiate either for the chemical properties of the waters and their topographic location. The first group of springs, called salt-bromoiodic, with higher salinity and temperature, is located in the upper part of Porretta along the Rio Maggiore, a tributary on the left bank of the Reno River. This is the portion of the deposit that has been studied. The second group of springs, called sulphurous, characterized by lower temperatures and salinity, is located south-east Porretta on the left side of the Reno River. These thermo-mineral water resources appear to be very worthy and need particular care and protection. By using the results of past research, the essential bibliography of which has been edited in the end-notes, the aim was to develop the hydrogeological parameters of the aquifer that feeds the thermo-mineral sources, identify and understand the conceptual model of the groundwater circulation system, also detecting the interference between the different sources in the area examined. This type of research, which is usually applied to aquifers in sedimentary and granular soils, can be considered original. Indeed, an exhaustive hydrodynamic parameterization of a fractured thermal aquifer system such as that of Porretta has never been conducted. The collection of observational data on the hydrological regime and on the chemical composition of hot waters during the six months of field surveys, which confirmed the substantial constancy of the values over time, was also remarkable.

Understanding hydrothermal circulation patterns at a low-enthalpy thermal spring using audio-magnetotelluric data: A case study from Ireland

2016 ◽  
Vol 132 ◽  
pp. 1-16 ◽  
Author(s):  
Sarah Blake ◽  
Tiernan Henry ◽  
Mark R. Muller ◽  
Alan G. Jones ◽  
John Paul Moore ◽  
...  
Keyword(s):  
Thermal Spring ◽  
Hydrothermal Circulation ◽  
Magnetotelluric Data ◽  
Circulation Patterns

scholarly journals Population Exposure to Compound Droughts and Heatwaves in the Observations and ERA5 Reanalysis Data in the Gan River Basin, China

Land ◽  
2021 ◽  
Vol 10 (10) ◽  
pp. 1021
Author(s):  
Yuqing Zhang ◽  
Guangxiong Mao ◽  
Changchun Chen ◽  
Liucheng Shen ◽  
Binyu Xiao
Keyword(s):  
River Basin ◽  
Population Change ◽  
Reanalysis Data ◽  
Maximum Temperature ◽  
Daily Maximum Temperature ◽  
Circulation System ◽  
Population Exposure ◽  
Daily Maximum ◽  
The One ◽  
Background Fields

The frequency, duration, and magnitude of heatwaves and droughts are expected to increase in a warming climate, which can have profound impacts on the environment, society, and public health, and these may be severely affected specifically by compound droughts and heatwaves (CDHWs). On the basis of daily maximum temperature data and the one-month standardized precipitation evapotranspiration index (SPEI) from 1961 to 2018, the Gan River Basin (GRB) was taken as a case here to construct CDHW identification indicators and quantify the population exposure to CDHWs. We found that ERA5 reanalysis data performed well in overall simulating temperature, precipitation, one-month SPEI, heatwaves, and CDHWs in the GRB from 1961 to 2018. CDHWs during the period from 1997 to 2018 were slightly higher than that in 1961–1997. CDHWs were more likely to occur in the southern parts of the basin due to the relatively high values of drought–heatwave dependence indices. Atmospheric circulation analysis of the 2003 CDHW in the GRB showed a relatively long-lasting anomalous high pressure and anticyclonic circulation system, accompanied by the positive convective inhibition and surface net solar radiation anomalies. These circulating background fields eventually led to the exceptional 2003 CDHW occurrence in the GRB. The population exposure to CDHWs basically increased, especially for the moderate CDHWs in ERA5. The change in total exposure was mainly due to climate change. Compared with the period from 1989 to 1998, the contributions of the population change effect in 2009–2018 gradually increased with the increase in the CDHW magnitude both in the observations and ERA5 reanalysis data.

Ewamiania thermalis gen. et sp. nov. (Cyanobacteria, Scytonemataceae), a new cyanobacterium from Talaroo thermal springs, north-eastern Australia

2017 ◽  
Vol 30 (1) ◽  
pp. 38 ◽  
Author(s):  
Glenn B. McGregor ◽  
Barbara C. Sendall
Keyword(s):  
16S Rrna ◽  
Phylogenetic Analyses ◽  
Thermal Spring ◽  
Thermal Waters ◽  
Monophyletic Clade ◽  
Vegetative Cells ◽  
Eastern Australia ◽  
North Eastern ◽  
Rrna Sequences ◽  
16S Rrna Sequences

A new subaerophytic cyanobacterium, Ewamiania thermalis gen. et sp. nov., was isolated from a thermal spring complex in tropical, north-eastern Australia and characterised using combined morphological and phylogenetic attributes. It formed blackish-green hemispherical caespitose mats that began as small circular tufts, maturing to form dense mats up to several metres long. It grew along the crests of the minidams just above the thermal waters as well as along some of the shallow unconfined areas of vent-discharge aprons. Morphologically, Ewamiania is most similar to members of the Scytonemataceae. Filaments were isopolar, cylindrical, straight or flexuous, densely arranged and erect, often parallely fasciculate, with tolypotrichoid false-branching, rarely with scytonematoid false-branching. Vegetative cells were short barrel-shaped or isodiametric, slightly constricted at the cross-walls, with granulated contents. Sheaths were firm, thick, lamellated, uncoloured to yellowish or darkly yellow–brown in colour, cylindrical and closed at the apex. Heterocytes were spherical or ovoid in shape, and occurred in both basal and intercalary positions, generally solitary, but sometimes up to two or three in a series, developing particularly at the base of branches. Reproduction occurred by the production of hormogonia by the formation of necridic cells; hormogonia were not constricted at cross-walls and often included terminal heterocytes. Phylogenetic analyses using partial 16S rRNA sequences obtained from a strain of E. thermalis showed that it formed a well supported monophyletic clade, sharing less than 94.3% nucleotide similarity with other cyanobacterial sequences, including putatively related taxa within the Scytonemataceae. It also formed a novel clade in the nifH phylogeny, which was associated with members of the genus Brasilonema M.F.Fiore, Sant’Anna, M.T.P.Azevedo, Komárek, Kastovsky, Sulek & Lorenzi.

scholarly journals On the quantity and quality of the gases disengaged from the thermal spring which supplies the King’s Bath, in the city of Bath

1837 ◽  
Vol 3 ◽  
pp. 254-256
Keyword(s):  
Central Area ◽  
Thermal Spring ◽  
Great Depth ◽  
White Lead ◽  
Thermal Waters ◽  
Hot Bath ◽  
Average Quantity ◽  
Series Of Experiments ◽  
The City

The author, pursuant to an intention expressed in a former paper read to the Society, undertook a series of experiments, for the purpose of measuring the gas evolved from the thermal springs at Bath during a period of time sufficiently long to enable him to determine with tolerable precision its average amount, and to ascertain whether any great diurnal variations in its quantity can be detected. He also kept during the same period a corresponding register of the conditions of the atmosphere, as to temperature, humidity and pressure, in order to learn whether any connexion could be traced between these conditions and the quantities of gas evolved. The supplies, both of water and of gas, from the Hot Bath and the Cross Bath being insignificant compared with those from the King’s Bath, the author confined his inquiries to the last of these, and chiefly to the gas arising from the apertures within its central area, which is about twenty feet in diameter; the other apertures without this circle from which gas issued being carefully stopped up. The gas was collected by a funnel-shaped apparatus, constructed of several sheets of iron riveted together, and the seams rendered airtight by white lead, supported on a frame, with contrivances for raising and lowering it as occasion might require. The observations were made during periods of from five to fifteen minutes, and continued daily from the 17th of September to the 18th of October inclusive. The average quantity of gas evolved per minute, as deduced from the mean of all the observations, is 267 cubic inches, giving a total daily volume of 223 cubic feet. The author, by referring to the accounts on record of other thermal waters, concludes that the evolution of gas is a phenomenon as intimately connected with the constitution of these waters, as the presence of a definite quantity of certain saline ingredients, or the possession of a particular temperature; both of which probably continue unaltered for periods of indefinite duration, compared with the records of any human history. He considers this phenomenon to be explicable, by supposing that a large volume of these gases is pent up in some cavern of rock, at a great depth below the surface of the earth, which, at some former period, had been heated by volcanic action, and which, by the gradual cooling and consequent contraction of its external portions, exerts a continued pressure on the gaseous contents of its cavity, and determines the uniform flow of a stream of gas through crevices towards the surface.

scholarly journals A new model for a hydrothermal circulation system and limit of the life

2017 ◽  
Vol 123 (4) ◽  
pp. 237-250 ◽  
Author(s):  
Jun-ichiro Ishibashi ◽  
Katsunori Yanagawa ◽  
Ken Takai
Keyword(s):  
Circulation System ◽  
Hydrothermal Circulation ◽  
New Model
Sign in / Sign up

Export Citation Format

Share Document