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Sample records for ground thermal regime

  1. Changes in the 1963-2013 shallow ground thermal regime in Russian permafrost regions

    NASA Astrophysics Data System (ADS)

    Streletskiy, Dmitry A.; Sherstiukov, Artem B.; Frauenfeld, Oliver W.; Nelson, Frederick E.

    2015-12-01

    Spatial variability and temporal trends of the shallow ground thermal regime and permafrost active-layer thickness (ALT) were estimated over 1963-2013 using daily soil temperature data available from stations of the Russian Hydrometeorological Service. Correlation analysis was used to evaluate the role of changing climatic conditions on the ground thermal regime. ALT data collected by the Circumpolar Active Layer Monitoring program in Russia were used to expand the geography of ALT observations over 1999-2013, and to identify ‘hot spots’ of soil temperature and ALT change. Results indicate that a substantially higher rate of change in the thermal regime of permafrost-affected soils prevailed during 1999-2013, relative to the last fifty years. Results indicate that the thermal regime of the upper permafrost in western Russia is strongly associated with air temperature, with much weaker relationships in central and eastern Russia. The thermal regime of permafrost-affected soils shows stronger dependence on climatic conditions over the last fifteen years relative to the historical 50-year period. Geostatistical analysis revealed that the cities of Norilsk and Susuman are hot spots of permafrost degradation. Of six settlements selected for detailed analysis in various parts of the permafrost regions, all but one (Chukotka), show substantial changes in the shallow ground thermal regime. Northern locations in the continuous permafrost region show thickening of the active layer, while those farther south experienced development of residual thaw layers above the permafrost and decreases in the duration of the freezing period.

  2. Influence of the seasonal snow cover on the ground thermal regime: An overview

    NASA Astrophysics Data System (ADS)

    Zhang, Tingjun

    2005-12-01

    The presence of seasonal snow cover during the cold season of the annual air temperature cycle has significant influence on the ground thermal regime in cold regions. Snow has high albedo and emissivity that cool the snow surface, high absorptivity that tends to warm the snow surface, low thermal conductivity so that a snow layer acts as an insulator, and high latent heat due to snowmelt that is a heat sink. The overall impact of snow cover on the ground thermal regime depends on the timing, duration, accumulation, and melting processes of seasonal snow cover; density, structure, and thickness of seasonal snow cover; and interactions of snow cover with micrometeorological conditions, local microrelief, vegetation, and the geographical locations. Over different timescales either the cooling or warming impact of seasonal snow cover may dominate. In the continuous permafrost regions, impact of seasonal snow cover can result in an increase of the mean annual ground and permafrost surface temperature by several degrees, whereas in discontinuous and sporadic permafrost regions the absence of seasonal snow cover may be a key factor for permafrost development. In seasonally frozen ground regions, snow cover can substantially reduce the seasonal freezing depth. However, the influence of seasonal snow cover on seasonally frozen ground has received relatively little attention, and further study is needed. Ground surface temperatures, reconstructed from deep borehole temperature gradients, have increased by up to 4°C in the past centuries and have been widely used as evidence of paleoclimate change. However, changes in air temperature alone cannot account for the changes in ground temperatures. Changes in seasonal snow conditions might have significantly contributed to the ground surface temperature increase. The influence of seasonal snow cover on soil temperature, soil freezing and thawing processes, and permafrost has considerable impact on carbon exchange between the

  3. New insights into the ground thermal regime of talus slopes with permafrost below the timberline

    NASA Astrophysics Data System (ADS)

    Schwindt, Daniel; Kneisel, Christof

    2013-04-01

    In the central Alps permafrost can be expected above 2400 m a.s.l., at altitudes where mean annual air temperatures are below -1° C. However, isolated permafrost occurrences are present in north-exposed talus slopes, far below the timberline, where mean annual air temperatures are positive. Driving factors are assumed to be a low income of solar radiation, a thick organic layer with high insulation capacities as well as the thermally induced chimney effect (Wakonigg, 1996). Investigated are three talus slopes with permafrost in the Swiss Alps that differ with regard to elevation level, talus material, humus characteristics and vegetation composition as well as the mean annual air temperatures. Aim is to achieve a deeper understanding of the factors determining the site-specific thermal regime, as well as the spatially limited and temporally highly variable permafrost occurrences in vegetated talus slopes. Focus is not solely on the question of why permafrost exists at these sites, but also why permafrost does not exist in the immediate surroundings. To detect the temporal variability and spatial heterogeneity of the permafrost occurrences, electrical resistivity tomography monitoring, seismic refraction tomography monitoring, and quasi-3D ERT were applied. To determine the ground thermal regime, air-, ground surface-, and humus temperatures, as well as temperatures within vents of the chimneys were recorded. Furthermore, humus characteristics (thickness, -temperature and -moisture) were mapped in permafrost-affected slope areas and in the immediate surroundings. To test the correlation between solar radiation, permafrost distribution, and humus/vegetation composition, digital elevation models were used to calculate the income of solar radiation. The areal extent of the permafrost bodies coincide precisely with slope sections where the organic layer is thickest, a consistent moss cover is present, and where temperatures at the transition between humus layer and

  4. Simulating the thermal regime and thaw processes of ice-rich permafrost ground with the land-surface model CryoGrid 3

    NASA Astrophysics Data System (ADS)

    Westermann, S.; Langer, M.; Boike, J.; Heikenfeld, M.; Peter, M.; Etzelmüller, B.; Krinner, G.

    2015-08-01

    Thawing of permafrost in a warming climate is governed by a complex interplay of different processes, of which only conductive heat transfer is taken into account in most model studies. However, observations in many permafrost landscapes demonstrate that lateral and vertical movement of water can have a pronounced influence on the thaw trajectories, creating distinct landforms like thermokarst ponds and lakes even in areas where permafrost is otherwise thermally stable. Novel process parameterizations are required to include such phenomena in future projections of permafrost thaw and hereby triggered climatic feedbacks. In this study, we present a new land-surface scheme designed for permafrost applications, CryoGrid 3, which constitutes a flexible platform to explore new parameterizations for a range of permafrost processes. We document the model physics and employed parameterizations for the basis module CryoGrid 3, and compare model results with in-situ observations of surface energy balance, surface temperatures, and ground thermal regime from the Samoylov permafrost observatory in NE Siberia. The comparison suggests that CryoGrid 3 can not only model the evolution of the ground thermal regime in the last decade, but also consistently reproduce the chain of energy transfer processes from the atmosphere to the ground. In addition, we demonstrate a simple 1-D parameterization for thaw process in permafrost areas rich in ground ice, which can phenomenologically reproduce both formation of thermokarst ponds and subsidence of the ground following thawing of ice-rich subsurface layers. Long-term simulation from 1901-2100 driven by reanalysis data and climate model output demonstrate that the hydrological regime can both accelerate and delay permafrost thawing. If meltwater from thawed ice-rich layers can drain, the ground subsides while at the same time the formation of a talik is delayed. If the meltwater pools at the surface, a pond is formed which enhances heat

  5. Simulating the thermal regime and thaw processes of ice-rich permafrost ground with the land-surface model CryoGrid 3

    NASA Astrophysics Data System (ADS)

    Westermann, S.; Langer, M.; Boike, J.; Heikenfeld, M.; Peter, M.; Etzelmüller, B.; Krinner, G.

    2016-02-01

    Thawing of permafrost in a warming climate is governed by a complex interplay of different processes of which only conductive heat transfer is taken into account in most model studies. However, observations in many permafrost landscapes demonstrate that lateral and vertical movement of water can have a pronounced influence on the thaw trajectories, creating distinct landforms, such as thermokarst ponds and lakes, even in areas where permafrost is otherwise thermally stable. Novel process parameterizations are required to include such phenomena in future projections of permafrost thaw and subsequent climatic-triggered feedbacks. In this study, we present a new land-surface scheme designed for permafrost applications, CryoGrid 3, which constitutes a flexible platform to explore new parameterizations for a range of permafrost processes. We document the model physics and employed parameterizations for the basis module CryoGrid 3, and compare model results with in situ observations of surface energy balance, surface temperatures, and ground thermal regime from the Samoylov permafrost observatory in NE Siberia. The comparison suggests that CryoGrid 3 can not only model the evolution of the ground thermal regime in the last decade, but also consistently reproduce the chain of energy transfer processes from the atmosphere to the ground. In addition, we demonstrate a simple 1-D parameterization for thaw processes in permafrost areas rich in ground ice, which can phenomenologically reproduce both formation of thermokarst ponds and subsidence of the ground following thawing of ice-rich subsurface layers. Long-term simulation from 1901 to 2100 driven by reanalysis data and climate model output demonstrate that the hydrological regime can both accelerate and delay permafrost thawing. If meltwater from thawed ice-rich layers can drain, the ground subsides, as well as the formation of a talik, are delayed. If the meltwater pools at the surface, a pond is formed that enhances heat

  6. A thermal ground cloak

    NASA Astrophysics Data System (ADS)

    Yang, Tianzhi; Wu, Qinghe; Xu, Weikai; Liu, Di; Huang, Lujun; Chen, Fei

    2016-02-01

    The thermal cloak has been a long-standing scientific dream of researchers and engineers. Recently thermal metamaterials with man-made micro-structure have been presented based on the principle of transformation optics (TO). This new concept has received considerable attention, which is a powerful tool for manipulating heat flux in thermal imaging systems. However, the inherent material singularity has long been a captivation of experimental realization. As an alternative method, the scattering-cancellation-based cloak (or bi-layer thermal cloak) has been presented to remove the singularity for achieving the same cloaking performance. Nevertheless, such strategy needs prerequisite knowledge (geometry and conductivity) of the object to be cloaked. In this paper, a new thermal ground cloak is presented to overcome the limitations. The device is designed, fabricated and measured to verify the thermal cloaking performance. We experimentally show that the remarkably low complexity of the device can fully and effectively be manipulated using realizable transformation thermal devices. More importantly, this thermal ground cloak is designed to exclude heat flux without knowing the information of the cloaked object.

  7. The thermal regime beneath cultural blocky materials: Ground temperature measurements in and around the Scythian Kurgans of the Russian Altay Mountains.

    NASA Astrophysics Data System (ADS)

    van de Kerchove, Ruben; Goossens, Rudi

    2010-05-01

    During historical times, the Altay Mountains were repeatedly occupied by several, mainly nomadic, cultures. Among them were the Scythians who lived in the area (and far beyond), from the 8th until the 2nd century BC. This culture is widely known for their specific burial rituals, including the burying of their death in a kurgan: a burial mound consisting of a coarse debris surface layer, overlaying a burial chamber. Due to this composition, together with the continental alpine climate of the Altay Mountains, several of these graves were found frozen, thanks to the existence of ice lenses and permafrost beneath the structures. If frozen, these kurgans contained well preserved bodies, often with the tattoos on their skin intact. As nowadays a distinct temperature rising is showed in these continental mountain ranges, the hundreds of kurgans, and especially these ones located at the lower fringe of the permafrost area, are likely to defrost within decades. As a result, the valuable, frozen, organic and inorganic content will get lost, resulting in a loss of extremely valuable cultural heritage and knowledge. Therefore, extensive permafrost research regarding the thermal state of the frozen tombs and the spatial distribution of the mountain permafrost is necessary to forecast which of the tombs are endangered by thawing. In the framework of this project a first expedition was organized in the Russian Altay Mountains during the summer of 2008. During this expedition, the valleys of Dzhazator, Tarkhata, Kalanegir and Ulandryk were visited in succession and temperature installments were made in order to give an overview of the thermal regime in the area. Beside installments intended for regional modelling, special sensors were placed in order to focus on the specific thermal regime related to the Scythian kurgans. This poster gives the first results of the temperature data as recorded by sensors located in and around the burial mounds. At first attention is given to the

  8. Mercury's thermal evolution and core crystallization regime

    NASA Astrophysics Data System (ADS)

    Rivoldini, A.; Van Hoolst, T.; Dumberry, M.; Steinle-Neumann, G.

    2015-10-01

    Unlike the Earth, where the liquid core isentrope is shallower than the core liquidus, at the lower pressures inside Mercury's core the isentrope can be steeper than the melting temperature. As a consequence, upon cooling, the isentrope may first enter a solid stability field near the core mantle boundary and produce ironrich snow that sinks under gravity and produces buoyant upwellings of iron depleted fluid. Similar to bottom up crystallization, crystallization initiated near the top might generate sufficient buoyancy flux to drive magnetic field generation by compositional convection.In this study we model Mercury's thermal evolution by taking into account the formation of iron-rich snow to assess when the conditions for an internally magnetic field can be satisfied. We employ a thermodynamic consistent description of the iron high-pressure phase diagram and thermoelastic properties of iron alloys as well as the most recent data about the thermal conductivity of core materials. We use a 1-dimensional parametrized thermal evolution model in the stagnant lid regime for the mantle (e.g. [1]) that is coupled to the core. The model for the mantle takes into account the formation of the crust due to melting at depth. Mantle convection is driven by heat producing radioactive elements, heat loss from secular cooling and from the heat supplied by the core. The heat generated inside the core is mainly provided from secular cooling, from the latent heat released at iron freezing, and from gravitational energy resulting form the release of light elements at the inner core-outer core boundary as well as from the sinking of iron-rich snow and subsequent upwellings of light elements in the snow zone. If the heat flow out of the core is smaller than the heat transported along the core isentrope a thermal boundary will from at the top of the outer core. To determine the extension of the convecting region inside the liquid core we calculate the convective power [2]. Finally, we

  9. CSDP: The seismology of continental thermal regimes

    SciTech Connect

    Aki, K.

    1990-05-01

    This is a progress report for the past one year of research (year 3 of 5-year project) under the project titled CSDP: Seismology of Continental Thermal Regime'', in which we proposed to develop seismological interpretation theory and methods applicable to complex structures encountered in continental geothermal areas and apply them to several candidate sites for the Continental Scientific Drilling Project. The past year has been extremely productive especially in the area of interpretation theory, including the following two major break-throughs. One is the derivation of an integral equation for time-dependent power spectra, which unified all the existing theories on seismic scattering (including the radiative transfer theory for total energy and single and multiple scattering theories based on the ray approach) and offers more complete and economical solutions to the problems of seismic scattering and attenuation. The other is the new formula for synthetic seismograms for layered media with irregular interfaces, combining the T-matrix method for an arbitrary shaped inclusion and the method of global generalized reflection/transmission coefficients for layered media. Both breakthroughs will enable us to deal with seismic observations in complex earth structures more efficiently and accurately. In the area of experimental studies, we discovered seismic guided waves trapped in the San Andreas fault near Parkfield, California. 54 refs., 14 figs.

  10. CSDP: Seismology of continental thermal regime

    SciTech Connect

    Aki, K.

    1989-04-01

    This is a progress report for the past one year of research (year 2 of 5-year project) under the project titled CSDP: Seismology of Continental Thermal Regime'', in which we proposed to develop seismological interpretation theory and methods applicable to complex structures encountered in continental geothermal areas and apply them to several candidate sites for the Continental Scientific Drilling Project. During the past year, two Ph.D. thesis works were completed under the present project. One is a USC thesis on seismic wave propagation in anisotropic media with application to defining fractures in the earth. The other is a MIT thesis on seismic Q and velocity structure for the magma-hydrothermal system of the Valles Caldera, New Mexico. The P.I. co-organized the first International Workshop on Volcanic Seismology at Capri, Italy in October 1988, and presented the keynote paper on the state-of-art of volcanic seismology''. We presented another paper at the workshop on Assorted Seismic Signals from Kilauea Volcano, Hawaii. Another international meeting, namely, the Chapman Conference on seismic anisotropy in the earth's crust at Berkeley, California in May 1988, was co-organized by the co-P.I. (P.C.L), and we presented our work on seismic waves in heterogeneous and anisotropic media. Adding the publications and presentations made in the past year to the list for the preceding year, the following table lists 21 papers published, submitted or presented in the past two years of the present project. 65 refs., 334 figs., 1 tab.

  11. Mercury's thermal evolution and core crystallization regime

    NASA Astrophysics Data System (ADS)

    Rivoldini, Attilio; Dumberry, Mathieu; Van Hoolst, Tim; Steinle-Neumann, Gerd

    2015-04-01

    Unlike the Earth, where the liquid core isentrope is less steep than the core melting temperature, at the lower pressures inside Mercury's core the isentrope can be steepper than the melting temperature. As a consequence, upon cooling, the isentrope may first cross the melting temperature near the core mantle boundary and produce iron-rich snow that sinks under gravity and produces buoyant upwellings of iron depleted fluid. Similar to bottom up crystallization, top down crystallization is expected to generate sufficient buoyancy flux to drive magnetic field generation by compositional convection. In this study we model Mercury's thermal evolution by taking into account the formation of iron-rich snow to assess when the conditions for internally magnetic field can be satisfied. We employ a thermodynamic consistent description of the iron high pressure phase diagram and thermoelastic properties of iron alloys as well as the most recent data about the thermal conductivity of core materials.

  12. Vegetation management with fire modifies peatland soil thermal regime.

    PubMed

    Brown, Lee E; Palmer, Sheila M; Johnston, Kerrylyn; Holden, Joseph

    2015-05-01

    Vegetation removal with fire can alter the thermal regime of the land surface, leading to significant changes in biogeochemistry (e.g. carbon cycling) and soil hydrology. In the UK, large expanses of carbon-rich upland environments are managed to encourage increased abundance of red grouse (Lagopus lagopus scotica) by rotational burning of shrub vegetation. To date, though, there has not been any consideration of whether prescribed vegetation burning on peatlands modifies the thermal regime of the soil mass in the years after fire. In this study thermal regime was monitored across 12 burned peatland soil plots over an 18-month period, with the aim of (i) quantifying thermal dynamics between burned plots of different ages (from <2 to 15 + years post burning), and (ii) developing statistical models to determine the magnitude of thermal change caused by vegetation management. Compared to plots burned 15 + years previously, plots recently burned (<2-4 years) showed higher mean, maximum and range of soil temperatures, and lower minima. Statistical models (generalised least square regression) were developed to predict daily mean and maximum soil temperature in plots burned 15 + years prior to the study. These models were then applied to predict temperatures of plots burned 2, 4 and 7 years previously, with significant deviations from predicted temperatures illustrating the magnitude of burn management effects. Temperatures measured in soil plots burned <2 years previously showed significant statistical disturbances from model predictions, reaching +6.2 °C for daily mean temperatures and +19.6 °C for daily maxima. Soil temperatures in plots burnt 7 years previously were most similar to plots burned 15 + years ago indicating the potential for soil temperatures to recover as vegetation regrows. Our findings that prescribed peatland vegetation burning alters soil thermal regime should provide an impetus for further research to understand the consequences of thermal regime

  13. Nonclassical radiation from thermal cavities in the ultrastrong coupling regime.

    PubMed

    Ridolfo, A; Savasta, S; Hartmann, M J

    2013-04-19

    Thermal or chaotic light sources emit radiation characterized by a slightly enhanced probability of emitting photons in bunches, described by a zero-delay second-order correlation function g((2))(0)=2. Here we explore photon-coincidence counting statistics of thermal cavities in the ultrastrong coupling regime, where the atom-cavity coupling rate becomes comparable to the cavity resonance frequency. We find that, depending on the system temperature and coupling rate, thermal photons escaping the cavity can display very different statistical behaviors, characterized by second-order correlation functions approaching zero or greatly exceeding two. PMID:23679600

  14. Effect of thermal noise on random lasers in diffusion regime

    NASA Astrophysics Data System (ADS)

    Zarei, Mohammad Ali; Hosseini-Farzad, Mahmood; Montakhab, Afshin

    2015-09-01

    In this paper, we study the effects of thermal noise on the time evolution of a weak light pulse (probe) in the presence of a strong light pulse (pump) within a gain medium which includes random scatterer particles. Suitable thermal noise term is added to a set of four coupled equations including three diffusion equations for energy densities and a rate equation for the upper level population in a four-level gain medium. These equations have been solved simultaneously by Crank-Nicholson numerical method. The main result is that the back-scattered output probe light is increased as the thermal noise strength is increased and simultaneously, with the same rate, the amplified spontaneous emission is decreased. Therefore, the amplified response of the random laser in diffusion regime for the input probe pulse is enhanced due to effect of the thermal noise.

  15. Geothermal regime and thermal history of the Llanos Basin, Columbia

    SciTech Connect

    Bachu, S.; Underschultz, J.R.; Ramon, J.C.; Villegas, M.E.

    1995-01-01

    The Llanos basin is a siliciclastic foreland sub-Andean sedimentary basin located in Columbia between the Cordillera Oriental and the Guyana Precambrian shield. Data on bottom-hole temperature, lithology, porosity, and vitrinite reflectance from all 318 wells drilled in the central and southern parts of the basin were used to analyze its geothermal regime and thermal history. Average geothermal gradients in the Llanos basin decrease generally with depth and westward toward the fold and thrust belt. The geothermal regime is controlled by a moderate, generally westward-decreasing basement heat flow, by depositional and compaction factors, and, in places, by advection by formation waters. Compaction leads to increased thermal conductivity with depth, whereas westward downdip flow in deep sandstone formations may exert a cooling effect in the central-western part of the basin. Vitrinite reflectance variation with depth shows a major discontinuity at the pre-Cretaceous unconformity. Areally, vitrinite reflectance increases southwestward in Paleozoic strata and northwestward in post-Paleozoic strata. These patterns indicate that the thermal history of the basin probably includes three thermal events that led to peaks in oil generation: a Paleozoic event in the southwest, a failed Cretaceous rifting event in the west, and an early Tertiary back-arc event in the west. Rapid cooling since the last thermal event is possibly caused by subhorizontal subduction of cold oceanic lithospheric plate.

  16. Laser ablation dynamics in metals: The thermal regime

    SciTech Connect

    Mezzapesa, F. P.; Brambilla, M.; Dabbicco, M.; Scamarcio, G.; Columbo, L. L.; Ancona, A.; Sibillano, T.

    2012-07-02

    We studied the laser ablation dynamics of steel in the thermal regime both experimentally and theoretically. The real-time monitoring of the process shows that the ablation rate depends on laser energy density and ambient pressure during the exposure time. We demonstrated that the ablation efficiency can be enhanced when the pressure is reduced with respect to the atmospheric pressure for a given laser fluence, reaching an upper limit despite of high-vacuum conditions. An analytical model based on the Hertz-Knudsen law reproduces all the experimental results.

  17. Historical thermal regimes define limits to coral acclimatization.

    PubMed

    Howells, Emily J; Berkelmans, Ray; van Oppen, Madeleine J H; Willis, Bette L; Bay, Line K

    2013-05-01

    Knowledge of the degree to which corals undergo physiological acclimatization or genetic adaptation in response to changes in their thermal environment is crucial to the success of coral reef conservation strategies. The potential of corals to acclimatize to temperatures exceeding historical thermal regimes was investigated by reciprocal transplantation of Acropora millepora colonies between the warm central and cool southern regions of the Great Barrier Reef (GBR) for a duration of 14 months. Colony fragments retained at native sites remained healthy, whereas transplanted fragments, although healthy over initial months when temperatures remained within native thermal regimes, subsequently bleached and suffered mortality during seasonal temperature extremes. Corals hosting Symbiodinium D transplanted to the southern GBR bleached in winter and the majority suffered whole (40%; n=20 colonies) or partial (50%) mortality at temperatures 1.1 degrees C below their 15-year native minimum. In contrast, corals hosting Symbiodinium C2 transplanted to the central GBR bleached in summer and suffered whole (50%; n=10 colonies) or partial (42%) mortality at temperatures 2.5 degrees C above their 15-year native maximum. During summer bleaching, the dominant Symbiodinium type changed from C2 to D within corals transplanted to the central GBR. Corals transplanted to the cooler, southern GBR grew 74-80% slower than corals at their native site, and only 50% of surviving colonies reproduced, at least partially because of cold water bleaching of transplants. Despite the absence of any visual signs of stress, corals transplanted to the warmer, central GBR grew 52-59% more slowly than corals at their native site before the summer bleaching (i.e., from autumn to spring). Allocation of energy to initial acclimatization or reproduction may explain this pattern, as the majority (65%) of transplants reproduced one month earlier than portions of the same colonies retained at the southern

  18. Photopyroelectric Technique, in the Thermally Thin Regime, for Thermal Effusivity Measurements of Liquids

    NASA Astrophysics Data System (ADS)

    Balderas-López, J. A.; Jaime-Fonseca, M. R.; Díaz-Reyes, J.; Gómez-Gómez, Y. M.; Bautista-Ramírez, M. E.; Muñoz-Diosdado, A.; Gálvez-Coyt, G.

    2016-02-01

    A photopyroelectric methodology using pyroelectric devices in the thermally thin regime, for the measurement of the thermal effusivity of liquids, is described. A commercial buzzer, taking advantage of the pyroelectric activity of the ceramic material (PZT in this case), is used to achieve this goal. Equivalence for thermal effusivity measurements between this photopyroelectric methodology and a previously reported photoacoustic technique, in the front configuration, is established. The thermal effusivity of six liquids was measured using this device, and very good agreement was found with corresponding values reported in the literature.

  19. Assessment of East Antarctic ice flow directions, ice grounding events, and glacial thermal regime across the middle Miocene climate transition from the ANDRILL-SMS and CRP drill holes

    NASA Astrophysics Data System (ADS)

    Passchier, S.; Hauptvogel, D.; Hansen, M.; Falk, C.; Martin, L.

    2010-12-01

    Here we present a synthesis of early and middle Miocene ice sheet development based on facies analyses and multiple compositional studies on the AND-2A and CRP drillcores from the Ross Sea, ca. 10 km off the coast of East Antarctica. The middle Miocene is characterized by one of the three largest shifts in deep-sea oxygen isotope records. During this time the East Antarctic ice sheet became dry-based at high elevation in the Transantarctic Mountains and advanced across the Ross Sea continental shelf to create widespread glacial unconformities. However, detailed proxy records also indicate that ice development was complex and may have occurred in a stepwise fashion, instead of one major episode. Our analyses of “grounded ice” diamictites from both the CRP and AND-2A cores show a significant change in composition across the middle Miocene transition. More detailed analyses of the stratigraphic distribution of facies, heavy mineral provenance, particle size, and major and trace element geochemistry in AND-2A show that relatively large polythermal ice-sheets similar in size to the modern were already present between 17.6 and 17.1 Ma. These results are in agreement with proxy records suggesting that Antarctic ice volumes were larger than today’s volume during the Mi-1b glaciation. Between 17.1 and 15.6-14.9 Ma, a predominance of iceberg debris sourced from the Ferrar Group in the Transantarctic Mountains suggests vigorous glacial erosion and fjord incision by East Antarctic outlet glaciers. The facies characteristics and comparison with compositional data from Neogene tills in the Transantarctic Mountains further suggest that the East Antarctic ice sheet may have been smaller than today during the Miocene climatic optimum (~17-15 Ma) with ice possibly reaching sea level only near the central Transantarctic Mountains. Advance of the grounding line and the development of glacial flow patterns compatible with a larger ice sheet than the modern commenced between 15

  20. Thermal regimes of major volcanic centers: magnetotelluric constraints

    SciTech Connect

    Hermance, J.F.

    1987-11-13

    The focus of activity at this laboratory is on applying natural electromagnetic methods along with other geophysical techniques to studying the dynamical processes and thermal regimes associated with centers of major volcanic activity. We are presently emphasizing studies of the Long Valley/Mono Craters Volcanic Complex, the Cascades Volcanic Belt, and the Valles Caldera. This work addresses questions regarding geothermal energy, chemical transport of minerals in the crust, emplacement of economic ore deposits, and optimal siting of drill-holes for scientific purposes. In addition, since much of our work is performed in the intermontane sedimentary basins of the western US (along with testing our field-system in some of the graben structures in the Northeast), there is an application of these studies to developing exploration and interpretational strategies for detecting and delineating structures associated with hydrocarbon reserves.

  1. Numerical modeling of thermal refraction inliquids in the transient regime

    NASA Astrophysics Data System (ADS)

    Kovsh, Dmitriy I.; Hagan, David J.; van Stryland, Eric W.

    1999-04-01

    We present the results of modeling of nanosecond pulse propagation in optically absorbing liquid media. Acoustic and electromagnetic wave equations must be solved simultaneously to model refractive index changes due to thermal expansion and/or electrostriction, which are highly transient phenomena on a nanosecond time scale. Although we consider situations with cylindrical symmetry and where the paraxial approximation is valid, this is still a computation-intensive problem, as beam propagation through optically thick media must be modeled. We compare the full solution of the acoustic wave equation with the approximation of instantaneous expansion (steady-state solution) and hence determine the regimes of validity of this approximation. We also find that the refractive index change obtained from the photo-acoustic equation overshoots its steady-state value once the ratio between the pulsewidth and the acoustic transit time exceeds a factor of unity.

  2. Thermal regime of soils in the atlantic high mountain. The central massiff of Picos de Europa (Spain)

    NASA Astrophysics Data System (ADS)

    Pisabarro, Alfonso; Serrano, Enrique; José González Trueba, Juan; Pellitero, Ramón

    2015-04-01

    The study of ground thermal regime has got large interest because determine significant geomorphological processes, particularly in the high mountain where do not exist vegetal cover on the ground. Picos de Europa massifs is located in the North of the Iberian Peninsula (43°18'to 43°7'N and 5°7' to 4°36'W, Spain). It is a wet and temperate high mountain environment characterized by the presence of calcareous rock, featured by karst processes and Pleistocene glaciers. The aim of this work is analyse the thermal behavior of ground along the year at different altitudes and know limits of ice presence on the ground to differentiate stages without ice, with seasonal ice or potential permafrost. Temperature data were obtained by 12 thermal micro sensors I-Bottom and UTL-Geotest AG data-logger with centesimal accuracy undertaken to 5-10 cm depth. Micro sensors distribution vary between 1110 and 2535 m a.s.l. exploiting the sites with best topoclimatic terms in order to obtain the coldest records like ancient glaciers. The period of recordings was 2003-2007. It was enough to obtain parameters like annual ground medium temperatures, freeze and thaw cycles, freeze index or number of months with temperatures below zero. Thermal phases on the ground have been obtained. The thermal regime varies according topoclimatic conditions in the sites above cryonival stage (above 1800 m a.s.l.). It was possible to determinate four phases; highest temperatures, autumn change, winter isotherm and melt. The winter isotherm is the longest phase (6-10 months) due to the intense snowfall. During this period do not exist thermal daily amplitude and the minimum and maximum temperatures are similar; always into the interval (-0.1°C to 0°C). However there are sites where the cold is enough to break the wintry isotherm during several days with records around -6°C. The days with freeze and thaw cycles are scarce and concentrated in autumn during periods without snow cover. Results show that

  3. Thermal Evolution and Crystallisation Regimes of the Martian Core

    NASA Astrophysics Data System (ADS)

    Davies, C. J.; Pommier, A.

    2015-12-01

    Though it is accepted that Mars has a sulfur-rich metallic core, its chemical and physical state as well as its time-evolution are still unconstrained and debated. Several lines of evidence indicate that an internal magnetic field was once generated on Mars and that this field decayed around 3.7-4.0 Gyrs ago. The standard model assumes that this field was produced by a thermal (and perhaps chemical) dynamo operating in the Martian core. We use this information to construct parameterized models of the Martian dynamo in order to place constraints on the thermochemical evolution of the Martian core, with particular focus on its crystallization regime. Considered compositions are in the FeS system, with S content ranging from ~10 and 16 wt%. Core radius, density and CMB pressure are varied within the errors provided by recent internal structure models that satisfy the available geodetic constraints (planetary mass, moment of inertia and tidal Love number). We also vary the melting curve and adiabat, CMB heat flow and thermal conductivity. Successful models are those that match the dynamo cessation time and fall within the bounds on present-day CMB temperature. The resulting suite of over 500 models suggest three possible crystallization regimes: growth of a solid inner core starting at the center of the planet; freezing and precipitation of solid iron (Fe- snow) from the core-mantle boundary (CMB); and freezing that begins midway through the core. Our analysis focuses on the effects of core properties that are expected to be constrained during the forthcoming Insight mission.

  4. Thermal regime of permafrost at Prudhoe Bay, Alaska

    USGS Publications Warehouse

    Lachenbruch, A.H.; Sass, J.H.; Marshall, B.V.; Moses, T.H., Jr.

    1982-01-01

    Temperature measurements through permafrost in the oil field at Prudhoe Bay, Alaska, combined with laboratory measurements of the thermal conductivity of drill cuttings permit an evaluation of in situ thermal properties and an understanding of the general factors that control the geothermal regime. A sharp contrast in temperature gradient at ~600 m represents a contrast in thermal conductivity caused by the downward change from interstitial ice to interstitial water at the base of permafrost under near steady-state conditions. Interpretation of the gradient contrast in terms of a simple model for the conductivity of an aggregate yields the mean ice content and thermal conductivities for the frozen and thawed sections (8.1 and 4.7 mcal/cm sec ?C, respectively). These results yield a heat flow of ~1.3 HFU which is similar to other values on the Alaskan Arctic Coast; the anomalously deep permafrost is a result of the anomalously high conductivity of the siliceous ice-rich sediments. Curvature in the upper 160 m of the temperature profiles represents a warming of ~1.8?C of the mean surface temperature, and a net accumulation of 5-6 kcal/cm 2 by the solid earth surface during the last 100 years or so. Rising sea level and thawing sea cliffs probably caused the shoreline to advance tens of kilometers in the last 20,000 years, inundating a portion of the continental shelf that is presently the target of intensive oil exploration. A simple conduction model suggests that this recently inundated region is underlain by near-melting ice-rich permafrost to depths of 300-500 m; its presence is important to seismic interpretations in oil exploration and to engineering considerations in oil production. With confirmation of the permafrost configuration by offshore drilling, heat-conduction models can yield reliable new information on the chronology of arctic shorelines.

  5. Towards a better understanding of rock wall thermal regime and stability in Norway

    NASA Astrophysics Data System (ADS)

    Sæterdal Myhra, Kristin; Etzelmüller, Bernd

    2013-04-01

    Hazardous rock fall events caused by slope failure have drawn attention towards the physical processes that affect slope stability of rock walls. The stability of a slope is determined by the interplay between driving and resisting forces acting on the site. A typical scenario is a gravity driving force that is counteracted by friction and cohesion forces. The nature of these forces is dependent on a complex interaction between a range of factors, amongst them topography, rock mass quality and hydrology. Steep topography increases the gravitational driving force, while factors such as water pressure and discontinuities in the rock mass decrease the resisting forces. Hence, slope instabilities evolve in time and space and is dependent upon a range of factors influencing each other through feedback processes. During the past century, the number of slope failures in the European Alps have increased, leading to an increasing focus on degrading permafrost as a possible factor for slope failure. Degrading permafrost might influence both the driving shear stresses and the resisting shear forces in frozen rock faces, causing changes in the force balance of the bedrock. Though degrading permafrost is considered to have an impact on the stability of rock slopes, the physical processes behind the causality are not fully understood. For the Scandinavian mountains, a possible relationship between permafrost and rock slope stability is poorly investigated and understood. Many unstable rock faces have been mapped and some are surveyed, and in several locations temperature loggers monitor the ground thermal regime in steep slopes. It is evident that many unstable rock faces are situated in or close to the zone of mountain permafrost. This project tries to contribute to the understanding of rock wall stability with respect to the influence of ground thermal regime and changing climatic conditions. A first goal of this study is to gain a better understanding of the sensitivity of

  6. Reduced thermal quadrupole heat transport modeling in harmonic and transient regime scanning thermal microscopy using nanofabricated thermal probes

    NASA Astrophysics Data System (ADS)

    Bodzenta, J.; Chirtoc, M.; Juszczyk, J.

    2014-08-01

    The thermal model of a nanofabricated thermal probe (NTP) used in scanning thermal microscopy is proposed. It is based on consideration of the heat exchange channels between electrically heated probe, a sample, and their surroundings, in transient and harmonic regimes. Three zones in the probe-sample system were distinguished and modeled by using electrical analogies of heat flow through a chain of quadrupoles built from thermal resistances and thermal capacitances. The analytical transfer functions for two- and three-cell quadrupoles are derived. A reduced thermal quadrupole with merged RC elements allows for thermo-electrical modeling of the complex architecture of a NTP, with a minimum of independent parameters (two resistance ratios and two time constants). The validity of the model is examined by comparing computed values of discrete RC elements with results of finite element simulations and with experimental data. It is proved that the model consisting of two or three-cell quadrupole is sufficient for accurate interpretation of experimental results. The bandwidth of the NTP is limited to 10 kHz. The performance in dc regime can be simply obtained in the limit of zero frequency. One concludes that the low NTP sensitivity to sample thermal conductivity is due, much like in dc regime, to significant heat by-pass by conduction through the cantilever, and to the presence of probe-sample contact resistance in series with the sample.

  7. Thermal regimes of major volcanic centers: Magnetotelluric constraints

    SciTech Connect

    Hermance, J.F.

    1989-10-02

    The interpretation of geophysical/electromagnetic field data has been used to study dynamical processes in the crust beneath three of the major tectono-volcanic features in North America: the Long Valley/Mono Craters Volcanic Complex in eastern California, the Cascades Volcanic Belt in Oregon, and the Rio Grande Rift in the area of Socorro, New Mexico. Primary accomplishments have been in the area of creating and implementing a variety of 2-D generalized inverse computer codes, and the application of these codes to fields studies on the basin structures and he deep thermal regimes of the above areas. In order to more fully explore the space of allowable models (i.e. those inverse solutions that fit the data equally well), several distinctly different approaches to the 2-D inverse problem have been developed: (1) an overdetermined block inversion; (2) an overdetermined spline inverstion; (3) a generalized underdetermined total inverse which allows one to tradeoff certain attributes of their model, such as minimum structure (flat models), roughness (smooth models), or length (small models). Moreover, we are exploring various approaches for evaluating the resolution model parameters for the above algorithms. 33 refs.

  8. Terrestrial Arctic Amplification Due to Changes in the Eurasian Soil Thermal Regime

    NASA Astrophysics Data System (ADS)

    Frauenfeld, O. W.; Chen, L.; Zhang, T.

    2012-12-01

    The Arctic amplification phenomenon suggests that due to feedbacks largely involving sea ice, increases in surface air temperature in response to greenhouse gas forcing are most pronounced in the Arctic. As the Arctic warms in response to climate change, the summer melt season lengthens and intensifies, leading to less sea ice at the end of summer. Absorption of solar radiation during summer in expanding open water areas increases the heat content of the ocean, delaying ice formation and promoting increased upward heat fluxes. Loss of sea ice thus provides a positive feedback that exacerbates the warming observed in the Arctic. The underlying premise of our study is that much like Arctic amplification due to the loss of sea ice, changes in the amount and distribution of frozen ground in Northern Hemisphere land areas represent a terrestrial analog to Arctic amplification. In response to climate warming we are observing increases in soil temperatures, deepening of the active layer, and talik formation in permafrost regions. This leads to delayed freeze-up of soils, decreased freeze depths in seasonally frozen ground regions, and earlier spring thaw. These changes in the soil thermal regime result in more and more heat storage in soils during the warm season, amplifying the frozen ground changes in high latitudes. The increased heat storage in the soil thermal regime results in a seasonal redistribution of energy, which leads to a substantially increased heat flux from the soil to the atmosphere during the cold season. It is this heat flux that represents our hypothesized feedback. We use monthly historical soil temperature observations at 423 station locations in the Eurasian high latitudes combined with soil properties based on the Harmonized World Soil Database to provide estimates of this soil heat flux. We calculate the temperature gradient based on soil temperature and, for a generalized assessment, first use a constant, estimated thermal conductivity for

  9. The thermal regime around buried submarine high voltage cables

    NASA Astrophysics Data System (ADS)

    Emeana, C. J.; Hughes, T. J.; Dix, J. K.; Gernon, T. M.; Henstock, T. J.; Thompson, C. E. L.; Pilgrim, J. A.

    2016-05-01

    The expansion of offshore renewable energy infrastructure and the need for trans-continental shelf power transmission require the use of submarine High Voltage (HV) cables. These cables have maximum operating surface temperatures of up to 70°C and are typically buried 1-2 m beneath the seabed, within the wide range of substrates found on the continental shelf. However, the heat flow pattern and potential effects on the sedimentary environments around such anomalously high heat sources in the near surface sediments are poorly understood. We present temperature measurements from a 2D laboratory experiment representing a buried submarine HV cable, and identify the thermal regimes generated within typical unconsolidated shelf sediments-coarse silt, fine sand and very coarse sand. We used a large (2 × 2.5 m) tank filled with water-saturated spherical glass beads (ballotini) and instrumented with a buried heat source and 120 thermocouples, to measure the time-dependent 2D temperature distributions. The observed and corresponding Finite Element Method (FEM) simulations of the steady state heat flow regimes, and normalised radial temperature distributions were assessed. Our results show that the heat transfer and thus temperature fields generated from submarine HV cables buried within a range of sediments are highly variable. Coarse silts are shown to be purely conductive, producing temperature increases of >10°C up to 40 cm from the source of 60°C above ambient; fine sands demonstrate a transition from conductive to convective heat transfer between c. 20°C and 36°C above ambient, with >10°C heat increases occurring over a metre from the source of 55°C above ambient; and very coarse sands exhibit dominantly convective heat transfer even at very low (c. 7°C) operating temperatures and reaching temperatures of up to 18°C above ambient at a metre from the source at surface temperatures of only 18°C. These findings are important for the surrounding near surface

  10. The thermal regime around buried submarine high-voltage cables

    NASA Astrophysics Data System (ADS)

    Emeana, C. J.; Hughes, T. J.; Dix, J. K.; Gernon, T. M.; Henstock, T. J.; Thompson, C. E. L.; Pilgrim, J. A.

    2016-08-01

    The expansion of offshore renewable energy infrastructure and the need for trans-continental shelf power transmission require the use of submarine high-voltage (HV) cables. These cables have maximum operating surface temperatures of up to 70 °C and are typically buried 1-2 m beneath the seabed, within the wide range of substrates found on the continental shelf. However, the heat flow pattern and potential effects on the sedimentary environments around such anomalously high heat sources in the near-surface sediments are poorly understood. We present temperature measurements from a 2-D laboratory experiment representing a buried submarine HV cable, and identify the thermal regimes generated within typical unconsolidated shelf sediments-coarse silt, fine sand and very coarse sand. We used a large (2 × 2.5 m2) tank filled with water-saturated spherical glass beads (ballotini) and instrumented with a buried heat source and 120 thermocouples to measure the time-dependent 2-D temperature distributions. The observed and corresponding Finite Element Method simulations of the steady state heat flow regimes and normalized radial temperature distributions were assessed. Our results show that the heat transfer and thus temperature fields generated from submarine HV cables buried within a range of sediments are highly variable. Coarse silts are shown to be purely conductive, producing temperature increases of >10 °C up to 40 cm from the source of 60 °C above ambient; fine sands demonstrate a transition from conductive to convective heat transfer between cf. 20 and 36 °C above ambient, with >10 °C heat increases occurring over a metre from the source of 55 °C above ambient; and very coarse sands exhibit dominantly convective heat transfer even at very low (cf. 7 °C) operating temperatures and reaching temperatures of up to 18 °C above ambient at a metre from the source at surface temperatures of only 18 °C. These findings are important for the surrounding near

  11. Numerical simulation of thermal-hydraulic generators running in a single regime

    NASA Astrophysics Data System (ADS)

    Chioreanu, Nicolae; Mitran, Tudor; Rus, Alexandru; Beles, Horia

    2014-06-01

    The paper presents the basis for the design of thermal-hydraulic generators running in a single regime. The thermal-hydraulic generators in a single regime running represent an absolute novelty worldwide (a pioneer invention). Based on the methodology concerning this subject, the design calculus for an experimental model was developed.

  12. Impact of various surface covers on water and thermal regime of Technosol

    NASA Astrophysics Data System (ADS)

    Kodešová, Radka; Fér, Miroslav; Klement, Aleš; Nikodem, Antonín; Teplá, Daniela; Neuberger, Pavel; Bureš, Petr

    2014-11-01

    Different soil covers influence water and thermal regimes in soils within urban areas. Knowledge of these regimes is needed, particularly when assessing effectiveness of energy gathering from soils using horizontal ground heat exchangers. The goal of this study was to calibrate the model HYDRUS-1D for simulating coupled water and thermal regime in Technosol type soils with grass cover, and to use this model for predicting water and thermal regimes under different materials covering the soil surface. For this purpose soil water contents were measured at depths of 10, 20, 30, 40, 60 and 100 cm at 4 locations and temperatures were measured at depths of 20, 40, 80, 120, 150 and 180 cm at three locations (all covered by grass) from June 2011 to December 2012. In addition sensors for simultaneous measuring soil water contents and temperatures were installed under different soil covers (grass, bark chips, sand, basalt gravel and concrete paving) at a depth of 7. The parameters of soil hydraulic properties were obtained on the 100-cm3 undisturbed soil samples using the multi-step outflow experiment and numerical inversion of the measured transient flow data using HYDRUS-1D. HYDRUS-1D was then used to simulated the water regime within the soil profile under the grass cover using climatic data from June 2011 to December 2012 and some of the soil hydraulic parameters were additionally numerically optimized using soil water contents measured at all depths. Water flow and heat transport were then simulated using these parameters, measured thermal properties and temperatures measured close to the surface applied as a top boundary condition. Simulated temperatures at all depths successfully approximated the measured data. Next, water and thermal regimes under another 4 different surface covers were simulated. Soil hydraulic properties of different materials were partly measured and partly optimized when simulating soil water regime from June 2011 to December 2012 using the soil

  13. THERMAL TEST ALCOVE HEATED DRIFT GROUND SUPPORT ANALYSIS

    SciTech Connect

    S. Bonabian

    1996-10-03

    The main purpose and objective of this analysis is to analyze the stability of the Thermal Test Facility Heated Drift and to design a ground support system. The stability of the Heated Drift is analyzed considering in situ, seismic, and thermal loading conditions. A ground support system is recommended to provide a stable opening for the Heated Drift. This report summarizes the results of the analyses and provides the details of the recommended ground support system for the Heated Drift. The details of the ground support system are then incorporated into the design output documents for implementation in the field.

  14. Power signatures of electric field and thermal switching regimes in memristive SET transitions

    NASA Astrophysics Data System (ADS)

    Mickel, Patrick R.; Hughart, David; Lohn, Andrew J.; Gao, Xujiao; Mamaluy, Denis; Marinella, Matthew J.

    2016-06-01

    We present a study of the ‘snap-back’ regime of resistive switching hysteresis in bipolar TaO x memristors, identifying power signatures in the electronic transport. Using a simple model based on the thermal and electric field acceleration of ionic mobilities, we provide evidence that the ‘snap-back’ transition represents a crossover from a coupled thermal and electric-field regime to a primarily thermal regime, and is dictated by the reconnection of a ruptured conducting filament. We discuss how these power signatures can be used to limit filament radius growth, which is important for operational properties such as power, speed, and retention.

  15. Active layer thermal regime at different vegetation covers at Lions Rump, King George Island, Maritime Antarctica

    NASA Astrophysics Data System (ADS)

    Almeida, Ivan C. C.; Schaefer, Carlos Ernesto G. R.; Fernandes, Raphael B. A.; Pereira, Thiago T. C.; Nieuwendam, Alexandre; Pereira, Antônio Batista

    2014-11-01

    Climate change impacts the biotic and abiotic components of polar ecosystems, affecting the stability of permafrost, active layer thickness, vegetation, and soil. This paper describes the active layer thermal regimes of two adjacent shallow boreholes, under the same soil but with two different vegetations. The study is location in Lions Rump, at King George Island, Maritime Antarctic, one of the most sensitive regions to climate change, located near the climatic limit of Antarctic permafrost. Both sites are a Turbic Cambic Cryosol formed on andesitic basalt, one under moss vegetation (Andreaea gainii, at 85 m a.s.l.) and another under lichen (Usnea sp., at 86 m a.s.l.), located 10 m apart. Ground temperature at same depths (10, 30 and 80 cm), water content at 80 cm depth and air temperature were recorded hourly between March 2009 and February 2011. The two sites showed significant differences in mean annual ground temperature for all depths. The lichen site showed a higher soil temperature amplitude compared to the moss site, with ground surface (10 cm) showing the highest daily temperature in January 2011 (7.3 °C) and the lowest daily temperature in August (- 16.5 °C). The soil temperature at the lichen site closely followed the air temperature trend. The moss site showed a higher water content at the bottommost layer, consistent with the water-saturated, low landscape position. The observed thermal buffering effect under mosses is primarily associated with higher moisture onsite, but a longer duration of the snowpack (not monitored) may also have influenced the results. Active layer thickness was approximately 150 cm at low-lying moss site, and 120 cm at well-drained lichen site. This allows to classify these soils as Cryosols (WRB) or Gelisols (Soil Taxonomy), with evident turbic features.

  16. Nuclear Thermal Propulsion Ground Test History

    NASA Technical Reports Server (NTRS)

    Gerrish, Harold P.

    2014-01-01

    Nuclear Thermal Propulsion (NTP) was started in 1955 under the Atomic Energy Commission as project Rover and was assigned to Los Alamos National Laboratory. The Nevada Test Site was selected in 1956 and facility construction began in 1957. The KIWI-A was tested on July 1, 1959 for 5 minutes at 70MW. KIWI-A1 was tested on July 8, 1960 for 6 minutes at 85MW. KIWI-A3 was tested on October 10, 1960 for 5 minutes at 100MW. The National Aeronautics and Space Administration (NASA) was formed in 1958. On August 31, 1960 the AEC and NASA established the Space Nuclear Propulsion Office and named Harold Finger as Director. Immediately following the formation of SNPO, contracts were awarded for the Reactor In Flight Test (RIFT), master plan for the Nuclear Rocket Engine Development Station (NRDS), and the Nuclear Engine for Rocket Vehicle Application (NERVA). From December 7, 1961 to November 30, 1962, the KIWI-B1A, KIWI-B1B, and KIWI-B4A were tested at test cell A. The last two engines were only tested for several seconds before noticeable failure of the fuel elements. Harold Finger called a stop to any further hot fire testing until the problem was well understood. The KIWI-B4A cold flow test showed the problem to be related to fluid dynamics of hydrogen interstitial flow causing fuel element vibrations. President Kennedy visited the NTS one week after the KIWI-B4A failure and got to see the engine starting to be disassembled in the maintenance facility. The KIWI-B4D and KIWI-B4E were modified to not have the vibration problems and were tested in test cell C. The NERVA NRX program started testing in early 1964 with NRX-A1 cold flow test series (unfueled graphite core), NRX-A2 and NRX-A3 power test series up to 1122 MW for 13 minutes. In March 1966, the NRX-EST (Engine System Test) was the first breadboard using flight functional relationship and total operating time of 116 minutes. The NRX-EST demonstrated the feasibility of a hot bleed cycle. The NRX-A5 had multiple start

  17. Thermal Regime of High-power Laser Diodes

    NASA Astrophysics Data System (ADS)

    Bezotosnyi, V. V.; Krokhin, O. N.; Oleshchenko, V. A.; Pevtsov, V. F.; Popov, Yu. M.; Cheshev, E. A.

    We discuss the design and application perspectives of different crystal, ceramic and composite-type submounts with thermo-compensating properties as well as submounts from materials with high thermal conductivity for overcoming thermal problem in high-power laser diodes (LD) and improving thermal management of other high-power optoelectronic and electronic semiconductor devices. Thermal fields in high-power laser diodes were calculated in 3 D thermal model at CW operation for some heatsink designs taking into account the experimental dependence of laser total efficiency against pumping current in order to extend the range of reliable operation up to thermal loads 20-30 W and corresponding output optical power up to 15-20 W for 100 μm stripe laser diodes.

  18. Sensitivity of rock slope stability in relation to thermal regime - examples from Norway

    NASA Astrophysics Data System (ADS)

    Myhra, K. S.; Etzelmuller, B.; Blikra, L. H.

    2014-12-01

    The steep topography in western and northern parts of Norway includes large unstable rock faces terminating into narrow fjords and lakes. The large number of such unstable faces lists rock slope failures as one of the bigger hazard threats in Norway. Successive studies have revealed presence of permafrost in Norway and a number of the unstable rock slope faces are located in mountain permafrost regions. It is known that thawing permafrost influences the rock-mechanical interplay in the bedrock and can hence play a role in the early stage of destabilization in rock walls. At present, both borehole measurements and several modelling studies for Norwegian mountains clearly indicate increasing ground temperatures during the last decades. As a first step in this study, a numerical study of the sensitivity of permafrost to climatic changes was performed for a number of sites along a latitudinal transect in Norway. Together with the thermal condition, lithology, structure and inclination are important conditions for the force regime in rock walls. In this study, the nature of temperature dependence on rock wall stability has been investigated through numerical modelling and the sensitivity of different factors related to these conditions has been evaluated in terms of stability, including the thermal regime. The focus has been on the initial conditions that are important for typical Norwegian rock wall sites and in particular for the sites where the simulations of the permafrost sensitivity have been performed. The analysis was applied for the Nordnes mountain in northern Norway, which is continuously surveyed due to the possible danger if large rock falls may hit the fjord water body generating tsunamis.

  19. A thermal profile method to identify potential ground-water discharge areas and preferred salmonid habitats for long river reaches

    USGS Publications Warehouse

    Vaccaro, J.J.; Maloy, K.J.

    2006-01-01

    The thermal regime of riverine systems is a major control on aquatic ecosystems. Ground water discharge is an important abiotic driver of the aquatic ecosystem because it provides preferred thermal structure and habitat for different types of fish at different times in their life history. In large diverse river basins with an extensive riverine system, documenting the thermal regime and ground-water discharge is difficult and problematic. A method was developed to thermally profile long (5-25 kilometers) river reaches by towing in a Lagrangian framework one or two probes that measure temperature, depth, and conductivity. One probe is towed near the streambed and, if used, a second probe is towed near the surface. The probes continuously record data at 1-3-second intervals while a Global Positioning System logs spatial coordinates. The thermal profile provides valuable information about spatial and temporal variations in habitat, and, notably, indicates ground-water discharge areas. This method was developed and tested in the Yakima River Basin, Washington, in summer 2001 during low flows in an extreme drought year. The temperature profile comprehensively documents the longitudinal distribution of a river's temperature regime that cannot be captured by fixed station data. The example profile presented exhibits intra-reach diversity that reflects the many factors controlling the temperature of a parcel of water as it moves downstream. Thermal profiles provide a new perspective on riverine system temperature regimes that represent part of the aquatic habitat template for lotic community patterns.

  20. Thermal Methods for Investigating Ground-Water Recharge

    USGS Publications Warehouse

    Blasch, Kyle W.; Constantz, Jim; Stonestrom, David A.

    2007-01-01

    Recharge of aquifers within arid and semiarid environments is defined as the downward flux of water across the regional water table. The introduction of recharging water at the land surface can occur at discreet locations, such as in stream channels, or be distributed over the landscape, such as across broad interarroyo areas within an alluvial ground-water basin. The occurrence of recharge at discreet locations is referred to as focused recharge, whereas the occurrence of recharge over broad regions is referred to as diffuse recharge. The primary interest of this appendix is focused recharge, but regardless of the type of recharge, estimation of downward fluxes is essential to its quantification. Like chemical tracers, heat can come from natural sources or be intentionally introduced to infer transport properties and aquifer recharge. The admission and redistribution of heat from natural processes such as insolation, infiltration, and geothermal activity can be used to quantify subsurface flow regimes. Heat is well suited as a ground-water tracer because it provides a naturally present dynamic signal and is relatively harmless over a useful range of induced perturbations. Thermal methods have proven valuable for recharge investigations for several reasons. First, theoretical descriptions of coupled water-and-heat transport are available for the hydrologic processes most often encountered in practice. These include land-surface mechanisms such as radiant heating from the sun, radiant cooling into space, and evapotranspiration, in addition to the advective and conductive mechanisms that usually dominate at depth. Second, temperature is theoretically well defined and readily measured. Third, thermal methods for depths ranging from the land surface to depths of hundreds of meters are based on similar physical principles. Fourth, numerical codes for simulating heat and water transport have become increasingly reliable and widely available. Direct measurement of water

  1. Thermal regime of active layer at two lithologically contrasting sites on James Ross Island, Antarctic Peninsula.

    NASA Astrophysics Data System (ADS)

    Hrbáček, Filip; Nývlt, Daniel; Láska, Kamil

    2016-04-01

    Antarctic Peninsula region (AP) represents one of the most rapidly warming parts of our planet in the last 50 years. Despite increasing research activities along both western and eastern sides of AP in last decades, there is still a lot of gaps in our knowledge relating to permafrost, active layer and its thermal and physical properties. This study brings new results of active layer monitoring on James Ross Island, which is the largest island in northern AP. Its northern part, Ulu Peninsula, is the largest ice-free area (more than 200 km2) in the region. Due its large area, we focused this study on sites located in different lithologies, which would affect local thermal regime of active layer. Study site (1) at Abernethy Flats area (41 m a.s.l.) lies ~7 km from northern coast. Lithologically is formed by disintegrated Cretaceous calcareous sandstones and siltstones of the Santa Marta Formation. Study site (2) is located at the northern slopes of Berry Hill (56 m a.s.l.), about 0.4 km from northern coastline. Lithology is composed of muddy to intermediate diamictites, tuffaceous siltstones to fine grained sandstones of the Mendel Formation. Data of air temperature at 2 meters above ground and the active layer temperatures at 75 cm deep profiles were obtained from both sites in period 1 January 2012 to 31 December 2014. Small differences were found when comparing mean air temperatures and active temperatures at 5 and 75 cm depth in the period 2012-2014. While the mean air temperatures varied between -7.7 °C and -7.0 °C, the mean ground temperatures fluctuated between -6.6 °C and -6.1 °C at 5 cm and -6.9 °C and -6.0 °C at 75 cm at Abernethy Flats and Berry Hill slopes respectively. Even though ground temperature differences along the profiles weren't pronounced during thawing seasons, the maximum active layer thickness was significantly larger at Berry Hill slopes (80 to 82 cm) than at Abernethy Flats (52 to 64 cm). We assume this differences are affected by

  2. The DOE Thermal Regimes Drilling Program through 1987

    SciTech Connect

    Not Available

    1988-07-01

    In response to strong endorsement from the scientific community, in the form of a report by the Continental Scientific Drilling Committee of the National Academy of Sciences (CSDC, 1984), the Office of Basic Energy Sciences of the DOE undertook a program of investigations of young magmatic intrusions and their associated thermal systems. To date, the effort has encompassed the first phases of a program to investigate the roots of active hydrothermal systems and has also investigated the thermal, chemical, and mechanical behavior of geologically recent (less than 600 years) magmatic extrusions. Shallow to intermediate-depth holes have been drilled and cored into hydrothermal systems in the silicic Valles and Long Valley calderas and at the crustal spreading center of the Salton Trough. These projects are briefly summarized here and are covered in greater detail in the accompanying appendices.

  3. Advanced concepts in ground thermal energy storage systems

    NASA Astrophysics Data System (ADS)

    Woods, Kevin David

    In recent years, ground thermal energy storage has become a topic of interest in the energy community for solar thermal energy storage systems, ground sourced heat pump systems, and data center thermal management systems due to an increase in the energy efficiency of such systems utilizing the ground as a thermal reservoir. The most common method for transferring thermal energy to the ground formation is the geothermal borehole. This dissertation presents the state of the art in geothermal borehole modeling and derives novel analytical functions to model advanced concepts concerning their operation. The novel solutions derived allow a geothermal borehole designer to better understand and design ground energy storage systems. The state of the art in geothermal borehole modeling is the stationary line source solution which is limited to boreholes operating without groundwater flow. Novel solutions for modeling a geothermal borehole with groundwater advection are presented through derivation of a transient moving line source solution as well as a transient moving cylindrical surface source solution. These solutions are applied to model a specific type of open loop geothermal borehole called a standing column well with groundwater advection and are compared to empirical and numerical data for validation. The dissertation then moves into derivation of a property determination method for geothermal boreholes with groundwater advection. The traditional property determination method used to obtain ground formation properties is based on the stationary transient line source method and fails in the presence of groundwater flow. The proposed novel property determination method calculates the thermal conductivity, thermal diffusivity, and superficial flow velocity of groundwater within a ground formation. These methods and solutions are novel tools allowing for geothermal borehole designers to grasp a better understanding of the systems they are designing as well as open other

  4. Effluent treatment options for nuclear thermal propulsion system ground tests

    SciTech Connect

    Shipers, L.R.; Brockmann, J.E.

    1992-10-16

    A variety of approaches for handling effluent from nuclear thermal propulsion system ground tests in an environmentally acceptable manner are discussed. The functional requirements of effluent treatment are defined and concept options are presented within the framework of these requirements. System concepts differ primarily in the choice of fission-product retention and waste handling concepts. The concept options considered range from closed cycle (venting the exhaust to a closed volume or recirculating the hydrogen in a closed loop) to open cycle (real time processing and venting of the effluent). This paper reviews the strengths and weaknesses of different methods to handle effluent from nuclear thermal propulsion system ground tests.

  5. Subsurface hydro-thermal regime and the atmospheric hydroclimate by a climate model

    NASA Astrophysics Data System (ADS)

    Saito, K.

    2009-04-01

    experiments were run for 20 years, forced by the climatological sea surface temperature and sea ice concentrations derived from the 1981-2000 period, after 150-year spin-up for the subsurface regime. The last 9 years were taken for the analysis. Different complexity of the subsurface hydro-thermal physics simulated different near-surface thermal states and seasonality. The refined physics showed warmer summer and cooler winter. The difference was most apparent in high latitudes; surface air temperature increased about 2°C in summer (zonal average, only over land), and decreased by about 5°C in winter. The improved physics and the presence of the top organic layer kept more ground ice during the warmer seasons. The total amount of soil moisture (i.e. soil wetness), however, did not change by the change of the physics. This helped mitigating the unrealistically fast and large flux of heat within the ground and at the interface between the atmosphere and the land surface, and fed back to the change in the subsurface thermal regime (e.g., active layer depth, or length of ground freezing), and affected the seasonality. It also led to improvement of the cumulative temperature indices for the atmospheric forcing in the warm and cold season (e.g. Thaw and Freezing Index). . The difference in the near-surface thermal state in high latitudes also affected snow accumulation in winter,earlier and larger for the finer physics, although precipitation did not vary largely except in the lower latitudes, at the southern flank of the Tibetan Plateau, where large precipitation differences were found during the summer monsoonal period, leading to a contrast between wetter Tibetan Plateau and drier coastal China. Land-average total annual runoff did not vary greatly between integrations at all latitudes; however, its seasonal distribution showed large difference. During the melting season, high-latitude runoff was greater for the finer physics due to shallower active layer, whereas it was

  6. Monitoring the Thermal Regime at Hot Creek and Vicinity, Long Valley Caldera, Eastern California

    NASA Astrophysics Data System (ADS)

    Clor, L. E.; Hurwitz, S.; Howle, J.

    2015-12-01

    Hot Creek Gorge contains the most obvious surface expression of the hydrothermal system in Long Valley Caldera, California, discharging 200-300 L/s of thermal water according to USGS measurements made since 1988. Formerly, Hot Creek was a popular public swimming area, but it was closed in 2006 due to unpredictable temperature fluctuations and sporadic geysering of thermal water within the creek (Farrar et al. USGS Fact Sheet2007-3045). The USGS has monitored the thermal regime in the area since the mid-1980s, including a long-term series of studies 0.6 km away at well CH-10b. Temperature measurements in the ~100 m deep well, which have been performed on an intermittent basis since it was drilled in 1983, reveal a complex temperature profile. Temperatures increase with depth to a maximum at about 45 meters below the ground surface, and then decrease steadily to the bottom of the well. The depth of the temperature maximum in the well (~45 m) corresponds to an elevation of ~2,120 m, roughly equivalent to the elevation of Hot Creek, and appears to sample the same hydrothermal flow system that supplies thermal features at the surface in the gorge. Starting in the early 1990s, the maximum temperature in CH-10b rose from 93.4°C to its peak in 2007 at 101.0°C. A cooling trend was observed beginning in 2009 and continues to present (99.3°C in June 2015). As the input into CH-10b is at the elevation of the creek, it exhibits the potential for response to thermal events at Hot Creek, and could provide a useful tool for monitoring future hazards. On short timescales, CH-10b also responds to large global earthquakes, greater than ~M7. These responses are captured with continuously logged high-frequency data (5s), and are usually characterized by a co-seismic water level drop of up to ten centimeters. Water levels tend to recover to pre-earthquake levels within a few hours to days.

  7. The cryptoendolithic microbial environment in the Ross Desert of Antarctica: mathematical models of the thermal regime

    NASA Technical Reports Server (NTRS)

    Nienow, J. A.; McKay, C. P.; Friedmann, E. I.

    1988-01-01

    Microbial activity in the Antarctic cryptoendolithic habitat is regulated primarily by temperature. Previous field studies have provided some information on the thermal regime in this habitat, but this type of information is limited by the remoteness of the site and the harsh climatic conditions. Therefore, a mathematical model of the endolithic thermal regime was constructed to augment the field data. This model enabled the parameters affecting the horizontal and altitudinal distribution of the community to be examined. The model predicts that colonization should be possible on surfaces with zenith angle less than 15 degrees. At greater zenith angles, colonization should be restricted to surfaces with azimuth angles less than 135 degrees or greater than 225 degrees. The upper elevational limit of the community should be less than 2,500 m. The thermal regime probably does not influence the zonation of the community within a rock.

  8. The cryptoendolithic microbial environment in the Ross Desert of Antarctica: mathematical models of the thermal regime.

    PubMed

    Nienow, J A; McKay, C P; Friedmann, E I

    1988-01-01

    Microbial activity in the Antarctic cryptoendolithic habitat is regulated primarily by temperature. Previous field studies have provided some information on the thermal regime in this habitat, but this type of information is limited by the remoteness of the site and the harsh climatic conditions. Therefore, a mathematical model of the endolithic thermal regime was constructed to augment the field data. This model enabled the parameters affecting the horizontal and altitudinal distribution of the community to be examined. The model predicts that colonization should be possible on surfaces with zenith angle less than 15 degrees. At greater zenith angles, colonization should be restricted to surfaces with azimuth angles less than 135 degrees or greater than 225 degrees. The upper elevational limit of the community should be less than 2,500 m. The thermal regime probably does not influence the zonation of the community within a rock. PMID:11538333

  9. The cryptoendolithic microbial environment in the Ross Desert of Antarctica: Mathematical models of the thermal regime.

    PubMed

    Nienow, J A; McKay, C P; Friedmann, E I

    1988-11-01

    Microbial activity in the Antarctic cryptoendolithic habitat is regulated primarily by temperature. Previous field studies have provided some information on the thermal regime in this habitat, but this type of information is limited by the remoteness of the site and the harsh climatic conditions. Therefore, a mathematical model of the endolithic thermal regime was constructed to augment the field data. This model enabled the parameters affecting the horizontal and altitudinal distribution of the community to be examined. The model predicts that colonization should be possible on surfaces with zenith angle less than 15°. At greater zenith angles, colonization should be restricted to surfaces with azimuth angles less than 135° or greater than 225°. The upper elevational limit of the community should be less than 2,500 m. The thermal regime probably does not influence the zonation of the community within a rock. PMID:24201713

  10. Thermal regime of the San Andreas Fault near Parkfield, California

    NASA Astrophysics Data System (ADS)

    Sass, J. H.; Williams, C. F.; Lachenbruch, Arthur H.; Galanis, S. P., Jr.; Grubb, F. V.

    1997-12-01

    Knowledge of the temperature variation with depth near the San Andreas fault is vital to understanding the physical processes that occur within the fault zone during earthquakes and creep events. Parkfield is near the southern end of the Coast Ranges segment of the San Andreas fault. This segment has higher mean heat flow than the Cape Mendocino segment to the northwest or the Mojave segment to the southeast. Boreholes were drilled specifically for the U.S. Geological Survey's Parkfield earthquake prediction experiment or converted from other uses at 25 sites within a few kilometers of the fault near Parkfield. These holes, which range in depth from 150 to over 1500m, were intended mainly for the deployment of volumetric strain meters, water-level recorders, and other downhole instruments. Temperature profiles were obtained from all the holes, and heat flow values were estimated from 17 of them. For a number of reasons, including a paucity of thermal conductivity data and rugged local topography, the accuracy of individual determinations was not sufficiently high to document local variations in heat flow. Values range from 54 to 92 mW m-2, with mean and 95% confidence limits of 74±4 mW m-2. This mean is slightly lower than the mean (83±3) of 39 previously published values from the central Coast Ranges, but it is consistent with the overall pattern of elevated heat flow in the Coast Ranges, and it is transitional to the mean of 68±2 mW m-2 that characterizes the Mojave segment of the San Andreas fault immediately to the south. The lack of a heat flow peak near the fault underscores the absence of a frictional thermal anomaly and provides additional support for a very small resolved shear stress parallel to the San Andreas fault and the nearly fault-normal maximum compressive stress observed in this region. Estimates of subsurface thermal conditions indicate that the seismicaseismic transition for the Parkfield segment corresponds to temperatures in the range of

  11. Thermal regimes in the Chukchi Sea from 1941-present

    NASA Astrophysics Data System (ADS)

    Luchin, Vladimir; Panteleev, Gleb

    2014-05-01

    The summer (June-October) temperature observations in the surface and subsurface (20m-bottom) Chukchi Sea layers collected from 1941-present have been analyzed using the self-consistent data recovery procedure based on correlation analysis and iterative empirical orthogonal function (EOF) decomposition. The analysis of the surface and subsurface EOFs identified "cold", "normal", and "warm" thermal states with variability of 2-4 years, and also 7-8 years. We found that the Chukchi Sea water temperature has gradually increased since 1941. Warming in the surface layer since 1941 has been minimal in the Bering Strait (0.8ºC) and maximalin Long Strait (2-2.4ºC). In the subsurface layer, the temperature increase is about half as much; minimal (0.2-0.5ºC) in Long Strait and rather uniform (0.7-1ºC) for the remaining Chukchi Sea. Analysis of the satellite sea surface height anomaly data shows that during the "warm" periods there is a stronger flow through the Bering Strait and intensification of the northwestward currents in the central Chukchi Sea. Extensive correlation analysis shows that the thermal state of the Chukchi Sea is strongly controlled by the flow of Pacific water through the Bering Strait and by an increase of the global atmospheric temperature. In addition, the typical circulation during the "warm" "warm" and "cold" periods was reconstructed using four dimensional variational (4Dvar) data assimilation into the ocean model, and estimates of volume and heat fluxes in the Chukchi Sea during "cold" and "warm" "warm" periods were derived which are consistent with EOF and correlation analyses.

  12. Thermal regimes in the Chukchi Sea from 1941 to 2008

    NASA Astrophysics Data System (ADS)

    Luchin, Vladimir; Panteleev, Gleb

    2014-11-01

    The summer (June-October) temperature observations in the surface (0 m) and subsurface (20 m-bottom) Chukchi Sea layers collected from 1941 to 2008 have been analyzed using the self-consistent data recovery procedure based on correlation analysis and iterative empirical orthogonal function (EOF) decomposition. The analysis of the surface and subsurface EOFs identified "cold", "normal", and "warm" thermal states with variability of 2-3 years, and also 4-7 years. We found that the Chukchi Sea water temperature has gradually increased since 1941. Warming in the surface layer since 1941 has been minimal in the Bering Strait (0.012 °C yr-1, total 0.8 °C) and maximal in Long Strait (0.030-0.036 °C yr-1, total 2.0-2.4 °C). In the subsurface layer, temperatures have increased about half as much; minimal (0.0030-0.0075 °C yr-1, total 0.2-0.5 °C) in Long Strait and rather uniform (0.010-0.015 °C yr-1, total 0.7-1.0 °C) for the remaining Chukchi Sea. Analysis of the satellite sea-surface height anomaly data shows that during the "warm" periods there is a stronger flow through the Bering Strait and intensification of the northwestward currents in the central Chukchi Sea. Extensive correlation analysis shows that the thermal state of the Chukchi Sea agrees well with the flow of Pacific water through the Bering Strait and by an increase of the global atmospheric temperature. In addition, typical circulation during "warm" and "cold" periods was reconstructed using four-dimensional variational (4Dvar) data assimilation into the ocean model, and estimates of volume and heat fluxes in the Chukchi Sea during "cold" and "warm" periods were derived which are consistent with EOF and correlation analyses.

  13. Importance of soil thermal regime in terrestrial ecosystem carbon dynamics in the circumpolar north

    NASA Astrophysics Data System (ADS)

    Jiang, Yueyang; Zhuang, Qianlai; Sitch, Stephen; O'Donnell, Jonathan A.; Kicklighter, David; Sokolov, Andrei; Melillo, Jerry

    2016-07-01

    In the circumpolar north (45-90°N), permafrost plays an important role in vegetation and carbon (C) dynamics. Permafrost thawing has been accelerated by the warming climate and exerts a positive feedback to climate through increasing soil C release to the atmosphere. To evaluate the influence of permafrost on C dynamics, changes in soil temperature profiles should be considered in global C models. This study incorporates a sophisticated soil thermal model (STM) into a dynamic global vegetation model (LPJ-DGVM) to improve simulations of changes in soil temperature profiles from the ground surface to 3 m depth, and its impacts on C pools and fluxes during the 20th and 21st centuries. With cooler simulated soil temperatures during the summer, LPJ-STM estimates ~ 0.4 Pg C yr- 1 lower present-day heterotrophic respiration but ~ 0.5 Pg C yr- 1 higher net primary production than the original LPJ model resulting in an additional 0.8 to 1.0 Pg C yr- 1 being sequestered in circumpolar ecosystems. Under a suite of projected warming scenarios, we show that the increasing active layer thickness results in the mobilization of permafrost C, which contributes to a more rapid increase in heterotrophic respiration in LPJ-STM compared to the stand-alone LPJ model. Except under the extreme warming conditions, increases in plant production due to warming and rising CO2, overwhelm the e nhanced ecosystem respiration so that both boreal forest and arctic tundra ecosystems remain a net C sink over the 21st century. This study highlights the importance of considering changes in the soil thermal regime when quantifying the C budget in the circumpolar north.

  14. Thermal regimes in bedrock and open fractures in the Nordnes rockslide, Norway

    NASA Astrophysics Data System (ADS)

    Hvidtfeldt Christiansen, Hanne; Harald Blikra, Lars

    2010-05-01

    The Nordnes rockslide site is located in the arctic part of the periglacial mountain landscape of Northern Norway at 69°30'N. It consists in the upper part of 1-10 m wide and 1-10 m deep open fractures. Extensive displacements measurements using GPS surveys, crackmeters, tiltmeter and lasers establish the intermunicipality monitoring programme, which shows ongoing deformation of the rockslide. In the rather special topographical setting of the open fractures we have during the International Polar Year 2007 to 2009 recorded the thermal regime of the upper part of the bedrock and of the air in the cracks for attempting to determine whether the recorded deformation can be geomorphologically controlled by bedrock surface expansion and contraction and/or by seasonal freezing or even by permafrost, or if only normal gravitational processes control the observed displacements. The upper 40 cm bedrock thermal conditions have been investigated in different exposures to identify the seasonal freezing depth and length, for determination of the influence of potential ice segregation processes causing weathering of the bedrock surfaces. The data show generally that that the bedrock surface is in the -3 to -8C freezing window for 3 to 6 months. Likewise 250 cm deep bedrock thermal monitoring have been carried out in three boreholes during one year at 900 m, 800 m and 625 m asl. extending over the area from the upper part of the unstable area and into the stable area above, for determination of the regional permafrost zone. These results in combination with thermal evidence from other deeper boreholes from the same setting in the same region show that seasonal freezing extends 5-10 m down, and that a potential active layer also is in the order of 5-10 m deep. The air temperatures in the cracks show significant cooling during winter, when the cracks have a thick snow cover, thus demonstrating the potential existence of permafrost in deeper part of the cracks and in the ground just

  15. Predicting thermal regimes of stream networks across the Chesapeake Bay Watershed: Natural and anthropogenic influences

    EPA Science Inventory

    Thermal regimes are a critical factor in models predicting joint effects of watershed management activities and climate change on fish habitat suitability. We have compiled a database of lotic temperature time series across the Chesapeake Bay Watershed (725 station-year combinat...

  16. Predicting Thermal Regimes of Stream Networks Across New England: Natural and Anthropogenic Influences

    EPA Science Inventory

    Thermal regime is a critical factor in models predicting joint effects of watershed management activities and climate change on habitat suitability for fish. We used a database of lotic temperature time series across New England (> 7000 station-year combinations) from state a...

  17. Incorporating Retention Time to Refine Models Predicting Thermal Regimes of Stream Networks Across New England

    EPA Science Inventory

    Thermal regimes are a critical factor in models predicting effects of watershed management activities on fish habitat suitability. We have assembled a database of lotic temperature time series across New England (> 7000 station-year combinations) from state and Federal data s...

  18. Network-based Prediction of Lotic Thermal Regimes Across New England

    EPA Science Inventory

    Thermal regimes are a critical factor in models predicting effects of watershed management activities on fish habitat suitability. We have assembled a database of lotic temperature time series across New England (> 7000 station-year combinations) from state and Federal data sour...

  19. Asymptotic regimes for the electrical and thermal conductivities in dense plasmas

    SciTech Connect

    Faussurier, G. Blancard, C.

    2015-04-15

    We study the asymptotic regimes for the electrical and thermal conductivities in dense plasmas obtained by combining the Chester–Thellung–Kubo–Greenwood approach and the Kramers approximation [Faussurier et al., Phys. Plasmas 21, 092706 (2014)]. Non-degenerate and degenerate situations are considered. The Wiedemann–Franz law is obtained in the degenerate case.

  20. Asymptotic regimes for the electrical and thermal conductivities in dense plasmas

    NASA Astrophysics Data System (ADS)

    Faussurier, G.; Blancard, C.

    2015-04-01

    We study the asymptotic regimes for the electrical and thermal conductivities in dense plasmas obtained by combining the Chester-Thellung-Kubo-Greenwood approach and the Kramers approximation [Faussurier et al., Phys. Plasmas 21, 092706 (2014)]. Non-degenerate and degenerate situations are considered. The Wiedemann-Franz law is obtained in the degenerate case.

  1. CRYogenic Orbital TEstbed Ground Test Article Thermal Analysis

    NASA Technical Reports Server (NTRS)

    Piryk, David; Schallhorn, Paul; Walls, Laurie; Stopnitzky, Benny; Rhys, Noah; Wollen, Mark

    2012-01-01

    The purpose of this study was to anchor thermal and fluid system models to CRYOTE ground test data. The CRYOTE ground test artide was jointly developed by Innovative Engineering Solutions, United Launch Alliance and NASA KSC. The test article was constructed out of a titanium alloy tank, Sapphire 77 composite skin (similar to G10), an external secondary payload adapter ring, thermal vent system, multi layer insulation and various data acquisition instrumentation. In efforts to understand heat loads throughout this system, the GTA (filled with liquid nitrogen for safety purposes) was subjected to a series of tests in a vacuum chamber at Marshall Space Flight Center. By anchoring analytical models against test data, higher fidelity thermal environment predictions can be made for future flight articles which would eventually demonstrate critical cryogenic fluid management technologies such as system chilldown, transfer, pressure control and long term storage. Significant factors that influenced heat loads included radiative environments, multi-layer insulation performance, tank fill levels and pressures and even contact conductance coefficients. This report demonstrates how analytical thermal/fluid networks were established and includes supporting rationale for specific thermal responses.

  2. Effective thermal conductivity of helium II: from Landau to Gorter-Mellink regimes

    NASA Astrophysics Data System (ADS)

    Sciacca, M.; Jou, D.; Mongiovì, M. S.

    2015-08-01

    The size-dependent and flux-dependent effective thermal conductivity of narrow channels filled with He II is analyzed. The classical Landau evaluation of the effective thermal conductivity of quiescent He II is extended to describe the transition to fully turbulent regime, where the heat flux is proportional to the cubic root of the temperature gradient (Gorter-Mellink regime). To do so, we use an expression for the quantum vortex line density L in terms of the heat flux considering the influence of the walls. From it, and taking into account the friction force of normal component against the vortices, we compute the effective thermal conductivity as a function of the heat flux, and we discuss in detail the corresponding size dependence.

  3. Ground-state cooling of a dispersively coupled optomechanical system in the unresolved sideband regime via a dissipatively coupled oscillator

    NASA Astrophysics Data System (ADS)

    Zhang, Yu-Xiang; Wu, Shengjun; Chen, Zeng-Bing; Shikano, Yutaka

    2016-08-01

    In the optomechanical cooling of a dispersively coupled oscillator, it is only possible to reach the oscillator ground state in the resolved sideband regime, where the cavity-mode linewidth is smaller than the resonant frequency of the mechanical oscillator being cooled. In this paper, we show that the dispersively coupled system can be cooled to the ground state in the unresolved sideband regime using an ancillary oscillator, which has a high quality factor and is coupled to the same optical mode via dissipative interaction. The ancillary oscillator has a resonant frequency close to that of the target oscillator; thus, the ancillary oscillator is also in the unresolved sideband regime. We require only a single blue-detuned laser mode to drive the cavity.

  4. Ground-based measurement of surface temperature and thermal emissivity

    NASA Technical Reports Server (NTRS)

    Owe, M.; Van De Griend, A. A.

    1994-01-01

    Motorized cable systems for transporting infrared thermometers have been used successfully during several international field campaigns. Systems may be configured with as many as four thermal sensors up to 9 m above the surface, and traverse a 30 m transect. Ground and canopy temperatures are important for solving the surface energy balance. The spatial variability of surface temperature is often great, so that averaged point measurements result in highly inaccurate areal estimates. The cable systems are ideal for quantifying both temporal and spatial variabilities. Thermal emissivity is also necessary for deriving the absolute physical temperature, and measurements may be made with a portable measuring box.

  5. Thermal effects on mass detection sensitivity of carbon nanotube resonators in nonlinear oscillation regime

    NASA Astrophysics Data System (ADS)

    Kang, Dong-Keun; Yang, Hyun-Ik; Kim, Chang-Wan

    2015-11-01

    A mass sensor using a nano-resonator has high detection sensitivity, and mass sensitivity is higher with smaller resonators. Therefore, carbon nanotubes (CNTs) are the ultimate materials for these applications and have been actively studied. In particular, CNT-based nanomechanical devices may experience high temperatures that lead to thermal expansion and residual stress in devices, which affects the device reliability. In this letter, to demonstrate the influence of the temperature change (i.e., thermal effect) on the mass detection sensitivity of CNT-based mass sensor, dynamic analysis is carried out for a CNT resonator with thermal effects in both linear and nonlinear oscillation regimes. Based on the continuum mechanics model, the analytical solution method with an assumed deflection eigenmode is applied to solve the nonlinear differential equation which involves the von Karman nonlinear strain-displacement relation and the additional axial force associated with thermal effects. A thermal effect on the fundamental resonance behavior and resonance frequency shift due to adsorbed mas, i.e., mass detection sensitivity, is examined in high-temperature environment. Results indicate a valid improvement of fundamental resonance frequency by using nonlinear oscillation in a thermal environment. In both linear and nonlinear oscillation regimes, the mass detection sensitivity becomes worse due to the increasing of temperature in a high-temperature environment. The thermal effect on the detection sensitivity is less effective in the nonlinear oscillation regime. It is concluded that a temperature change of a mass sensor with a CNT-based resonator can be utilized to enhance the detection sensitivity depending on the CNT length, linear/nonlinear oscillation behaviors, and the thermal environment.

  6. Modeling transitions in the hydrologic and thermal regimes of Earth's largest lake system

    NASA Astrophysics Data System (ADS)

    Gronewold, A.; Anderson, E. J.; Blanken, P.; Lofgren, B. M.; Wang, J.; Stow, C.

    2014-12-01

    Starting in the late 1990s, the seasonal hydrologic and thermal regimes of Earth's largest lake system have been characterized by very high surface water temperatures, below-average ice cover, persistent low water levels and extremely high over-lake evaporation rates. However, the harsh winter conditions of 2013-2014 led to very low surface water temperatures and an exceptionally broad and persistent areal extent of ice cover. The contrast between the extreme 2013-2014 winter conditions on the Great Lakes and the conditions from the preceding 15-year period raises compelling questions about the extent to which hydrometeorological conditions have changed in the Great Lakes region, how they might be expected to change in the future, and to what extent those changes are reflected in currrent regional research-oriented and operational forecasts. Here, we analyze historical intra-seasonal relationships between late winter and subsequent late fall thermal regimes on the Great Lakes and find that, for some of the lakes, memory of seasonal heat content is strong, but can be significantly impacted by hydrometeorological conditions including wind speed and solar radiation. In fact, we find that the late 1990s, a period coinciding with one of the strongest El Ninos on record, represent a shift in the hydrologic and thermal regimes of the Great Lakes, and that projections for the fall of 2014 suggest that the regime might be offset by the recent cold winter. Our findings also provide evidence that the transition in the Great Lakes' altered thermal regime in the late 1990s was triggered by abrupt increases not only in air and water temperatures associated with the coincident El Nino, but also by a combination of reduced cloud cover and above-average summer solar radiation. The extent to which these changes are explicitly represented in regional forecasting systems is critically important to regional water resource management planning.

  7. Regimes of microscale radiative transfer for exchange of thermal energy between metallic surfaces

    SciTech Connect

    Whale, M.D.; Cravalho, E.G.

    1997-07-01

    There is ample theoretical and experimental evidence to substantiate the enhanced transfer of energy by thermal radiation between two closely-spaced surfaces when the distance of separation is on the order of the characteristic wavelength of the radiation. There is no clear agreement, however, as to the magnitude of the effect. In the present work, they consolidate these various approaches for the first time, and they show the fundamental underlying reasons for the disparate experimental results and analytical models. They identify a set of microscale radiative transfer regimes that account for the different mechanisms of absorption that occur. For the various experimental configurations, they show that the disagreement among the experimental measurements performed thus far can be traced to the different microscale regimes that govern the absorption process. Furthermore, using these regimes they are able to explain the discrepancies between the analytical models and the experimental measurements.

  8. Ground temperature regime and periglacial dynamics in three different sites from the summit area in Sierra Nevada (southern Spain) from 2006 to 2012

    NASA Astrophysics Data System (ADS)

    Salvador-Franch, Ferran; Oliva, Marc; Salva-Catarineu, Montserrat; Gómez-Ortiz, Antonio

    2013-04-01

    Ground temperatures and its control on snow cover are crucial factors conditioning the activity of current periglacial processes in the highest lands of Sierra Nevada (Betique Range, Iberian Peninsula). We present summary results of the monitoring period from September 2006 to August 2012 in three sites with contrasting topography, aspect and snow cover. Temperatures loggers have recorded data at 2 hours time lapse at: a) Veleta glacial cirque, an environment with marginal permafrost and a small active rock glacier in it (3107 m asl), b) the flat summit plateau of Collado de los Machos (3297 m) characterized by the existence of inactive sorted circles with scarce snow cover, and c) the southern cirque of Rio Seco, an area with moderate snow cover and widespread solifluction lobes (3105 m). We discuss the periglacial activity in the three study sites in relation with ground temperatures. Results show evidence of the decisive control played by snow cover (duration and thickness) in the thermal regime of the ground (rhythm, depth and intensity of freezing). Only the site in the Veleta cirque has revealed the existence of permafrost, which is inexistent at the summit plateaus and southern cirques. The freezing and thawing of the ground depends substantially on the geographical characteristics of the sites, although a common pattern is detected: the thawing occurs more rapidly than the freezing and the number of freeze-thaw cycles in air temperatures is substantially higher than in ground temperatures.

  9. Active Thermal Control Experiments for LISA Ground Verification Testing

    NASA Astrophysics Data System (ADS)

    Higuchi, Sei; DeBra, Daniel B.

    2006-11-01

    The primary mission goal of LISA is detecting gravitational waves. LISA uses laser metrology to measure the distance between proof masses in three identical spacecrafts. The total acceleration disturbance to each proof mass is required to be below 3 × 10-15 m/s2√Hz . Optical path length variations on each optical bench must be kept below 40 pm/√Hz over 1 Hz to 0.1 mHz. Thermal variations due to, for example, solar radiation or temperature gradients across the proof mass housing will distort the spacecraft causing changes in the mass attraction and sensor location. We have developed a thermal control system developed for the LISA gravitational reference sensor (GRS) ground verification testing which provides thermal stability better than 1 mK/√Hz to f < 1 mHz and which by extension is suitable for in-flight thermal control for the LISA spacecraft to compensate solar irradiation. Thermally stable environment is very demanded for LISA performance verification. In a lab environment specifications can be met with considerable amount of insulation and thermal mass. For spacecraft, the very limited thermal mass calls for an active control system which can meet disturbance rejection and stability requirements simultaneously in the presence of long time delay. A simple proportional plus integral control law presently provides approximately 1 mK/√Hz of thermal stability for over 80 hours. Continuing development of a model predictive feed-forward algorithm will extend performance to below 1 mK/√Hz at f < 1 mHz and lower.

  10. Lunar thermal regime to 300 km. [in crust and upper mantle

    NASA Technical Reports Server (NTRS)

    Keihm, S. J.; Langseth, M. G.

    1977-01-01

    Coupling of the global heat flow, crustal heat source enrichment, thermal conductivity, and temperature in the crust and upper mantle of the moon is examined. A steady-state moon in which conductive heat transfer dominates is assumed. Heat-flow measurements from the Apollo 15 and 17 missions and gamma-ray mapping of thorium conducted by the Apollo 15 and 16 missions provide data for the study of the lunar thermal regime. Temperatures in the range of 1100 to 1600 K are found for the 300-km depth level. In the upper mantle, temperature gradients are in the range of 1.8 to 3.2 K/km.

  11. Boundary between the thermal and statistical polarization regimes in a nuclear spin ensemble

    NASA Astrophysics Data System (ADS)

    Herzog, B. E.; Cadeddu, D.; Xue, F.; Peddibhotla, P.; Poggio, M.

    2014-07-01

    As the number of spins in an ensemble is reduced, the statistical fluctuations in its polarization eventually exceed the mean thermal polarization. This transition has now been surpassed in a number of recent nuclear magnetic resonance experiments, which achieve nanometer-scale detection volumes. Here, we measure nanometer-scale ensembles of nuclear spins in a KPF6 sample using magnetic resonance force microscopy. In particular, we investigate the transition between regimes dominated by thermal and statistical nuclear polarization. The ratio between the two types of polarization provides a measure of the number of spins in the detected ensemble.

  12. Boundary between the thermal and statistical polarization regimes in a nuclear spin ensemble

    SciTech Connect

    Herzog, B. E.; Cadeddu, D.; Xue, F.; Peddibhotla, P.; Poggio, M.

    2014-07-28

    As the number of spins in an ensemble is reduced, the statistical fluctuations in its polarization eventually exceed the mean thermal polarization. This transition has now been surpassed in a number of recent nuclear magnetic resonance experiments, which achieve nanometer-scale detection volumes. Here, we measure nanometer-scale ensembles of nuclear spins in a KPF{sub 6} sample using magnetic resonance force microscopy. In particular, we investigate the transition between regimes dominated by thermal and statistical nuclear polarization. The ratio between the two types of polarization provides a measure of the number of spins in the detected ensemble.

  13. Thermal transport in Si and Ge nanostructures in the 'confinement' regime.

    PubMed

    Kwon, Soonshin; Wingert, Matthew C; Zheng, Jianlin; Xiang, Jie; Chen, Renkun

    2016-07-21

    Reducing semiconductor materials to sizes comparable to the characteristic lengths of phonons, such as the mean-free-path (MFP) and wavelength, has unveiled new physical phenomena and engineering capabilities for thermal energy management and conversion systems. These developments have been enabled by the increasing sophistication of chemical synthesis, microfabrication, and atomistic simulation techniques to understand the underlying mechanisms of phonon transport. Modifying thermal properties by scaling physical size is particularly effective for materials which have large phonon MFPs, such as crystalline Si and Ge. Through nanostructuring, materials that are traditionally good thermal conductors can become good candidates for applications requiring thermal insulation such as thermoelectrics. Precise understanding of nanoscale thermal transport in Si and Ge, the leading materials of the modern semiconductor industry, is increasingly important due to more stringent thermal conditions imposed by ever-increasing complexity and miniaturization of devices. Therefore this Minireview focuses on the recent theoretical and experimental developments related to reduced length effects on thermal transport of Si and Ge with varying size from hundreds to sub-10 nm ranges. Three thermal transport regimes - bulk-like, Casimir, and confinement - are emphasized to describe different governing mechanisms at corresponding length scales. PMID:27344991

  14. Thermal transport in Si and Ge nanostructures in the `confinement' regime

    NASA Astrophysics Data System (ADS)

    Kwon, Soonshin; Wingert, Matthew C.; Zheng, Jianlin; Xiang, Jie; Chen, Renkun

    2016-07-01

    Reducing semiconductor materials to sizes comparable to the characteristic lengths of phonons, such as the mean-free-path (MFP) and wavelength, has unveiled new physical phenomena and engineering capabilities for thermal energy management and conversion systems. These developments have been enabled by the increasing sophistication of chemical synthesis, microfabrication, and atomistic simulation techniques to understand the underlying mechanisms of phonon transport. Modifying thermal properties by scaling physical size is particularly effective for materials which have large phonon MFPs, such as crystalline Si and Ge. Through nanostructuring, materials that are traditionally good thermal conductors can become good candidates for applications requiring thermal insulation such as thermoelectrics. Precise understanding of nanoscale thermal transport in Si and Ge, the leading materials of the modern semiconductor industry, is increasingly important due to more stringent thermal conditions imposed by ever-increasing complexity and miniaturization of devices. Therefore this Minireview focuses on the recent theoretical and experimental developments related to reduced length effects on thermal transport of Si and Ge with varying size from hundreds to sub-10 nm ranges. Three thermal transport regimes - bulk-like, Casimir, and confinement - are emphasized to describe different governing mechanisms at corresponding length scales.

  15. Characterizing Ground and Thermal States of Few-Body Hamiltonians.

    PubMed

    Huber, Felix; Gühne, Otfried

    2016-07-01

    The question whether a given quantum state is a ground or thermal state of a few-body Hamiltonian can be used to characterize the complexity of the state and is important for possible experimental implementations. We provide methods to characterize the states generated by two- and, more generally, k-body Hamiltonians as well as the convex hull of these sets. This leads to new insights into the question of which states are uniquely determined by their marginals and to a generalization of the concept of entanglement. Finally, certification methods for quantum simulation can be derived. PMID:27419547

  16. Characterizing Ground and Thermal States of Few-Body Hamiltonians

    NASA Astrophysics Data System (ADS)

    Huber, Felix; Gühne, Otfried

    2016-07-01

    The question whether a given quantum state is a ground or thermal state of a few-body Hamiltonian can be used to characterize the complexity of the state and is important for possible experimental implementations. We provide methods to characterize the states generated by two- and, more generally, k -body Hamiltonians as well as the convex hull of these sets. This leads to new insights into the question of which states are uniquely determined by their marginals and to a generalization of the concept of entanglement. Finally, certification methods for quantum simulation can be derived.

  17. Computational Modeling of Radiative, Thermal, and Kinetic Regimes of Flame Spread

    NASA Astrophysics Data System (ADS)

    Simsek, Aslihan

    The purpose of this thesis presented is to analyze flame spread over thermally thin solid fuels in three regimes of flame spread process; radiative, thermal, and kinetic regimes. The analyses have been performed using a comprehensive two dimensional computational fluid dynamics (CFD) model written in Fortran language developed by Bhattacharjee. Flame spread over thermally thin fuels in quiescent and opposing flow microgravity environments is investigated. An extinction study is performed with different computational domain sizes for a set of fuel thicknesses to understand the effect of domain size on the extinction velocities in the radiative and kinetic regimes. The effect of development length boundary layer is studied in both radiative and kinetic regimes. It is found that flame spread rate, flame size, flame temperature, blow-off and radiative extinction velocities depend on the development length and the boundary layer created by the opposing flow. A correlation between the extinction development length and opposed flow velocity is established. Flame spread over open cell phenolic foam is investigated in detail in a quiescent microgravity environment. The critical fuel thickness is found at different oxygen concentrations and compared to those for PMMA. Pressure, oxygen concentration, and radiation studies are also performed to analyze the flame spread over foam. To understand the effect of radiation on flame spread, the CFD model is coupled with two different radiation models in a microgravity environment. The first radiation model includes gas to surface conduction, gas to environment radiation loss, gas to surface feedback radiation, and surface to environment radiation loss. The second model only excludes gas to surface radiation feedback. The results obtained using these two models are compared with the CFD results; one with radiation completely neglected, and one with only gas to surface radiation feedback neglected. Flame spread in downward

  18. Wave theories of non-laminar charged particle beams: from quantum to thermal regime

    NASA Astrophysics Data System (ADS)

    Fedele, Renato; Tanjia, Fatema; Jovanović, Dusan; de Nicola, Sergio; Ronsivalle, Concetta; Ronsivalle

    2014-04-01

    The standard classical description of non-laminar charged particle beams in paraxial approximation is extended to the context of two wave theories. The first theory that we discuss (Fedele R. and Shukla, P. K. 1992 Phys. Rev. A 45, 4045. Tanjia, F. et al. 2011 Proceedings of the 38th EPS Conference on Plasma Physics, Vol. 35G. Strasbourg, France: European Physical Society) is based on the Thermal Wave Model (TWM) (Fedele, R. and Miele, G. 1991 Nuovo Cim. D 13, 1527.) that interprets the paraxial thermal spreading of beam particles as the analog of quantum diffraction. The other theory is based on a recently developed model (Fedele, R. et al. 2012a Phys. Plasmas 19, 102106; Fedele, R. et al. 2012b AIP Conf. Proc. 1421, 212), hereafter called Quantum Wave Model (QWM), that takes into account the individual quantum nature of single beam particle (uncertainty principle and spin) and provides collective description of beam transport in the presence of quantum paraxial diffraction. Both in quantum and quantum-like regimes, the beam transport is governed by a 2D non-local Schrödinger equation, with self-interaction coming from the nonlinear charge- and current-densities. An envelope equation of the Ermakov-Pinney type, which includes collective effects, is derived for both TWM and QWM regimes. In TWM, such description recovers the well-known Sacherer's equation (Sacherer, F. J. 1971 IEEE Trans. Nucl. Sci. NS-18, 1105). Conversely, in the quantum regime and in Hartree's mean field approximation, one recovers the evolution equation for a single-particle spot size, i.e. for a single quantum ray spot in the transverse plane (Compton regime). We demonstrate that such quantum evolution equation contains the same information as the evolution equation for the beam spot size that describes the beam as a whole. This is done heuristically by defining the lowest QWM state accessible by a system of non-overlapping fermions. The latter are associated with temperature values that are

  19. A new regime of nanoscale thermal transport: Collective diffusion increases dissipation efficiency

    DOE PAGESBeta

    Hoogeboom-Pot, Kathleen M.; Hernandez-Charpak, Jorge N.; Gu, Xiaokun; Frazer, Travis D.; Anderson, Erik H.; Chao, Weilun; Falcone, Roger W.; Yang, Ronggui; Murnane, Margaret M.; Kapteyn, Henry C.; et al

    2015-03-23

    Understanding thermal transport from nanoscale heat sources is important for a fundamental description of energy flow in materials, as well as for many technological applications including thermal management in nanoelectronics and optoelectronics, thermoelectric devices, nanoenhanced photovoltaics, and nanoparticle-mediated thermal therapies. Thermal transport at the nanoscale is fundamentally different from that at the macroscale and is determined by the distribution of carrier mean free paths and energy dispersion in a material, the length scales of the heat sources, and the distance over which heat is transported. Past work has shown that Fourier’s law for heat conduction dramatically overpredicts the rate ofmore » heat dissipation from heat sources with dimensions smaller than the mean free path of the dominant heat-carrying phonons. In this work, we uncover a new regime of nanoscale thermal transport that dominates when the separation between nanoscale heat sources is small compared with the dominant phonon mean free paths. Surprisingly, the interaction of phonons originating from neighboring heat sources enables more efficient diffusive-like heat dissipation, even from nanoscale heat sources much smaller than the dominant phonon mean free paths. This finding suggests that thermal management in nanoscale systems including integrated circuits might not be as challenging as previously projected. In conclusion, we demonstrate a unique capability to extract differential conductivity as a function of phonon mean free path in materials, allowing the first (to our knowledge) experimental validation of predictions from the recently developed first-principles calculations.« less

  20. Consequences of thermal pollution from a nuclear plant on lake temperature and mixing regime

    NASA Astrophysics Data System (ADS)

    Kirillin, Georgiy; Shatwell, Tom; Kasprzak, Peter

    2013-07-01

    We investigated the combined effects of thermal pollution from a nuclear power plant (NPP) and regional climate warming on the thermal regime of a lake. For this purpose, we used the lake model FLake and analyzed 50 years of temperature data from Lake Stechlin, Germany, which served as the cooling water reservoir for the Rheinsberg NPP from 1966 until 1990. Both modeling and statistical data analysis revealed a strong influence of the NPP cooling water discharge on the lake water temperatures and the vertical stability of the water column. A remarkable effect of thermal pollution consisted of strong vertical mixing in winter produced by the discharge of warm water into the lake when ambient water temperatures were below 4 °C. This effect caused a significant increase in the deep hypolimnion temperatures and a corresponding decrease of the vertical stability in the summer. In turn, climate warming had the opposite effect on the summer stability by increasing lake surface temperatures. Both the thermal pollution and climate change increased the duration of the summer stratification period. Our results suggest that industrial thermal pollution in temperate lakes during winter is stored in the deep water column until the next winter, whereas heat added in the summer dissipates relatively rapidly into the atmosphere. Accordingly, the winter thermal pollution could have a long-lasting effect on the lake ecology by affecting benthic biogeochemical processes.

  1. A new regime of nanoscale thermal transport: Collective diffusion increases dissipation efficiency.

    PubMed

    Hoogeboom-Pot, Kathleen M; Hernandez-Charpak, Jorge N; Gu, Xiaokun; Frazer, Travis D; Anderson, Erik H; Chao, Weilun; Falcone, Roger W; Yang, Ronggui; Murnane, Margaret M; Kapteyn, Henry C; Nardi, Damiano

    2015-04-21

    Understanding thermal transport from nanoscale heat sources is important for a fundamental description of energy flow in materials, as well as for many technological applications including thermal management in nanoelectronics and optoelectronics, thermoelectric devices, nanoenhanced photovoltaics, and nanoparticle-mediated thermal therapies. Thermal transport at the nanoscale is fundamentally different from that at the macroscale and is determined by the distribution of carrier mean free paths and energy dispersion in a material, the length scales of the heat sources, and the distance over which heat is transported. Past work has shown that Fourier's law for heat conduction dramatically overpredicts the rate of heat dissipation from heat sources with dimensions smaller than the mean free path of the dominant heat-carrying phonons. In this work, we uncover a new regime of nanoscale thermal transport that dominates when the separation between nanoscale heat sources is small compared with the dominant phonon mean free paths. Surprisingly, the interaction of phonons originating from neighboring heat sources enables more efficient diffusive-like heat dissipation, even from nanoscale heat sources much smaller than the dominant phonon mean free paths. This finding suggests that thermal management in nanoscale systems including integrated circuits might not be as challenging as previously projected. Finally, we demonstrate a unique capability to extract differential conductivity as a function of phonon mean free path in materials, allowing the first (to our knowledge) experimental validation of predictions from the recently developed first-principles calculations. PMID:25831491

  2. A new regime of nanoscale thermal transport: Collective diffusion increases dissipation efficiency

    PubMed Central

    Hoogeboom-Pot, Kathleen M.; Hernandez-Charpak, Jorge N.; Gu, Xiaokun; Frazer, Travis D.; Anderson, Erik H.; Chao, Weilun; Falcone, Roger W.; Yang, Ronggui; Murnane, Margaret M.; Kapteyn, Henry C.; Nardi, Damiano

    2015-01-01

    Understanding thermal transport from nanoscale heat sources is important for a fundamental description of energy flow in materials, as well as for many technological applications including thermal management in nanoelectronics and optoelectronics, thermoelectric devices, nanoenhanced photovoltaics, and nanoparticle-mediated thermal therapies. Thermal transport at the nanoscale is fundamentally different from that at the macroscale and is determined by the distribution of carrier mean free paths and energy dispersion in a material, the length scales of the heat sources, and the distance over which heat is transported. Past work has shown that Fourier’s law for heat conduction dramatically overpredicts the rate of heat dissipation from heat sources with dimensions smaller than the mean free path of the dominant heat-carrying phonons. In this work, we uncover a new regime of nanoscale thermal transport that dominates when the separation between nanoscale heat sources is small compared with the dominant phonon mean free paths. Surprisingly, the interaction of phonons originating from neighboring heat sources enables more efficient diffusive-like heat dissipation, even from nanoscale heat sources much smaller than the dominant phonon mean free paths. This finding suggests that thermal management in nanoscale systems including integrated circuits might not be as challenging as previously projected. Finally, we demonstrate a unique capability to extract differential conductivity as a function of phonon mean free path in materials, allowing the first (to our knowledge) experimental validation of predictions from the recently developed first-principles calculations. PMID:25831491

  3. A new regime of nanoscale thermal transport: Collective diffusion increases dissipation efficiency

    SciTech Connect

    Hoogeboom-Pot, Kathleen M.; Hernandez-Charpak, Jorge N.; Gu, Xiaokun; Frazer, Travis D.; Anderson, Erik H.; Chao, Weilun; Falcone, Roger W.; Yang, Ronggui; Murnane, Margaret M.; Kapteyn, Henry C.; Nardi, Damiano

    2015-03-23

    Understanding thermal transport from nanoscale heat sources is important for a fundamental description of energy flow in materials, as well as for many technological applications including thermal management in nanoelectronics and optoelectronics, thermoelectric devices, nanoenhanced photovoltaics, and nanoparticle-mediated thermal therapies. Thermal transport at the nanoscale is fundamentally different from that at the macroscale and is determined by the distribution of carrier mean free paths and energy dispersion in a material, the length scales of the heat sources, and the distance over which heat is transported. Past work has shown that Fourier’s law for heat conduction dramatically overpredicts the rate of heat dissipation from heat sources with dimensions smaller than the mean free path of the dominant heat-carrying phonons. In this work, we uncover a new regime of nanoscale thermal transport that dominates when the separation between nanoscale heat sources is small compared with the dominant phonon mean free paths. Surprisingly, the interaction of phonons originating from neighboring heat sources enables more efficient diffusive-like heat dissipation, even from nanoscale heat sources much smaller than the dominant phonon mean free paths. This finding suggests that thermal management in nanoscale systems including integrated circuits might not be as challenging as previously projected. In conclusion, we demonstrate a unique capability to extract differential conductivity as a function of phonon mean free path in materials, allowing the first (to our knowledge) experimental validation of predictions from the recently developed first-principles calculations.

  4. Thermal stability of spent coffee ground polysaccharides: galactomannans and arabinogalactans.

    PubMed

    Simões, Joana; Maricato, Elia; Nunes, Fernando M; Domingues, M Rosário; Coimbra, Manuel A

    2014-01-30

    In order to better understand the thermal stability of spent coffee grounds (SCG) galactomannans and arabinogalactans and the reactions that can occur upon roasting, long term isothermal exposures, up to 3h, were performed at 160, 180, 200, 220, and 240 °C. The resultant products were analysed according to the sugars and linkage composition and also by electrospray mass spectrometry. Galactomannans did not loss mass at T ≤ 200 °C during exposures up to 3h whereas the arabinogalactans showed that thermal stability only for T ≤ 180 °C. This was in accordance with the estimated activation energies of their thermal decomposition of 138 kJ/mol and 94 kJ/mol, respectively. The roasting of galactomannans promoted the formation of new glycosidic linkages, with occurrence of 2-, 6-, 2,3-, 2,6-, 3,6-, 2,3,6-, 3,4,6-linked mannose residues, 3,4,6-linked galactose residues, and terminally-linked glucose residues, observed by methylation analysis. Depolymerisation and formation of anhydrohexose residues at the reducing end and mannose-glucose isomerisation were also observed. The roasting of galactomannans at 200 °C promoted their solubility in water upon alkali extraction and neutralisation. PMID:24299772

  5. Thermal Regime and Meteorological Parameters Monitoring in Alpine Permafrost Rockwalls: the Aiguille du Midi

    NASA Astrophysics Data System (ADS)

    Morra di Cella, U.; Cremonese, E.; Deline, P.; Gruber, S.; Pogliotti, P.; Ravanel, L.

    2009-04-01

    During the last decades the alpine region has revealed to be extremely sensitive to ongoing increasing temperatures and permafrost has been identified as one of six cryospheric indicators of global climate change. In high-mountain regions the permafrost evidences are scarse and punctual, while its occurrence is wide and its distribution is mainly controlled by complex topography and ground cover condition. In such environment, steep bedrock slopes are abundant and contain a significant proportion of permafrost whose thermal response is very fast compared to permafrost in gentle morphology because of its less amount of ice content. Due to logistical problems like accessibility, costs, weather conditions, etc..., monitoring sites in such environments are few, while an increase of measurements of rockwall temperature and system energy balance is fundamental for the calibration and validation of both physical and statistical permafrost models. Started in the framework of the French-Italian project PERMAdataROC (www.fondazionemontagnasicura.org/multimedia/permadataroc/) and presently developped within the EU co-funded project PermaNET (www.permanet-alpinespace.eu), several monitoring sites have been equipped during the last years in the Western Alps from a collaboration of Swiss, French and Italian researchers, with the aim to cover the widest range of climatic, topographic, morphological and geological conditions. In such network, the Aiguille du Midì can be considered one of the most advanced site in high-mountain permafrost research thanks to the convergence of several instrumental approaches, but also a "cooperation laboratory" among different research groups. The site has been choosen because of its elevation, aspects variability, steep slopes and accessibility all over the year. In details, ARPA Valle d'Aosta in collaboration with University of Zurich started in 2006 the monitoring of rockwall thermal regimes and of some meteorological parameters on the different

  6. Transition from the incoherent to the coherent regime for propagative-wave based thermal radiation

    NASA Astrophysics Data System (ADS)

    Tsurimaki, Y.; Chapuis, P.-O.; Okajima, J.; Komiya, A.; Maruyama, S.; Vaillon, R.

    2016-01-01

    The transition from the incoherent to the coherent regime for thermal radiation between bodies trough a transparent medium is discussed. The canonical case of two parallel semi-infinite planar media is used as a basis to provide an insight into the physics and quantities ruling the distance at which coherent effects have an impact on the propagative component of the net heat flux exchanged. A practical criterion is proposed to define the distance below which radiation intensity framework should not be used, but instead fluctuational electrodynamics.

  7. Ground test facilities for evaluating nuclear thermal propulsion engines and fuel elements

    SciTech Connect

    Allen, G.C.; Beck, D.F.; Harmon, C.D.; Shipers, L.R.

    1992-08-01

    Interagency panels evaluating nuclear thermal propulsion development options have consistently recognized the need for constructing a major new ground test facility to support fuel element and engine testing. This paper summarizes the requirements, configuration, and design issues of a proposed ground test complex for evaluating nuclear thermal propulsion engines and fuel elements being developed for the Space Nuclear Thermal Propulsion (SNTP) program. 2 refs.

  8. Crystallization upon thermal annealing of a glass-forming liquid crystal in the nematic regime

    SciTech Connect

    Mastrangelo, J.C. |; Blanton, T.N.; Chen, S.H. |

    1995-04-24

    As an example of a novel class of glass-forming liquid crystals, compound (I) was synthesized and characterized to possess a nematic mesophase between {ital T}{sub {ital g}} and {ital T}{sub {ital c}} as the pristine crystal was heated beyond its {ital T}{sub {ital m}} followed by quenching to below room temperature. Differential scanning calorimetry (DSC) and x-ray diffraction techniques were employed to investigate its morphological stability. It was found that the nematic mesophase persists upon annealing for a period of up to 22 h without the appearance of new phases. However, after annealing in the nematic regime over a longer period of time, thermally activated phase transformations were observed, resulting in a new crystalline phase plus the pristine crystalline phase based on DSC thermal transition data and x-ray diffraction patterns.

  9. Thermal and mechanical properties of selected 3D printed thermoplastics in the cryogenic temperature regime

    NASA Astrophysics Data System (ADS)

    Weiss, K.-P.; Bagrets, N.; Lange, C.; Goldacker, W.; Wohlgemuth, J.

    2015-12-01

    Insulating materials for use in cryogenic boundary conditions are still limited to a proved selection as Polyamid, Glasfiber reinforced resins, PEEK, Vespel etc. These materials are usually formed to parts by mechanical machining or sometimes by cast methods. Shaping complex geometries in one piece is limited. Innovative 3D printing is now an upcoming revolutionary technology to construct functional parts from a couple of thermoplastic materials as ABS, Nylon and others which possess quite good mechanical stability and allow realizing very complex shapes with very subtle details. Even a wide range of material mixtures is an option and thermal treatments can be used to finish the material structure for higher performance. The use of such materials in cryogenic environment is very attractive but so far poor experience exists. In this paper, first investigations of the thermal conductivity, expansion and mechanical strength are presented for a few selected commercial 3D material samples to evaluate their application prospects in the cryogenic temperature regime.

  10. Review of Nuclear Thermal Propulsion Ground Test Options

    NASA Technical Reports Server (NTRS)

    Coote, David J.; Power, Kevin P.; Gerrish, Harold P.; Doughty, Glen

    2015-01-01

    High efficiency rocket propulsion systems are essential for humanity to venture beyond the moon. Nuclear Thermal Propulsion (NTP) is a promising alternative to conventional chemical rockets with relatively high thrust and twice the efficiency of highest performing chemical propellant engines. NTP utilizes the coolant of a nuclear reactor to produce propulsive thrust. An NTP engine produces thrust by flowing hydrogen through a nuclear reactor to cool the reactor, heating the hydrogen and expelling it through a rocket nozzle. The hot gaseous hydrogen is nominally expected to be free of radioactive byproducts from the nuclear reactor; however, it has the potential to be contaminated due to off-nominal engine reactor performance. NTP ground testing is more difficult than chemical engine testing since current environmental regulations do not allow/permit open air testing of NTP as was done in the 1960's and 1970's for the Rover/NERVA program. A new and innovative approach to rocket engine ground test is required to mitigate the unique health and safety risks associated with the potential entrainment of radioactive waste from the NTP engine reactor core into the engine exhaust. Several studies have been conducted since the ROVER/NERVA program in the 1970's investigating NTP engine ground test options to understand the technical feasibility, identify technical challenges and associated risks and provide rough order of magnitude cost estimates for facility development and test operations. The options can be divided into two distinct schemes; (1) real-time filtering of the engine exhaust and its release to the environment or (2) capture and storage of engine exhaust for subsequent processing.

  11. Cold exposure and associated metabolic changes in adult tropical beetles exposed to fluctuating thermal regimes.

    PubMed

    Lalouette, L; Kostál, V; Colinet, H; Gagneul, D; Renault, D

    2007-04-01

    Environmental stress deleteriously affects every aspect of an ectotherm's biological function. Frequent exposure of terrestrial insects to temperature variation has thus led to the evolution of protective biochemical and physiological mechanisms. However, the physiological mechanisms underlying the positive impact of fluctuating thermal regimes (FTRs) on the fitness and survival of cold-exposed insects have not been studied. We have thus investigated the metabolic changes in adults of the beetle Alphitobius diaperinus in order to determine whether FTRs trigger the initiation of a metabolic response involving synthesis of protective compounds, such as free amino acids (FAAs) and polyols. The metabolic profile was analyzed during constant fluctuating thermal regimes (the beetles had daily pulses at higher temperatures that enabled them to recover) and compared with constant cold exposure and untreated controls. The increase of several essential amino acids (Lys, Iso, Leu, Phe and Trp) in cold-exposed beetles supports the conclusion that it results from the breakdown of proteins. Some FAAs have been shown to have cryoprotective properties in insects, but the relationship between FAAs, cold tolerance and survival has not yet been well defined. Instead of considering FAAs only as a part of the osmo- and cryoprotective arsenal, they should also be regarded as main factors involved in the multiple regulatory pathways activated during cold acclimation. Under FTRs, polyol accumulation probably contributes to the increased duration of survival in A. diaperinus. PMID:17331186

  12. Continental Scientific Drilling (CSD): Technology Barriers to Deep Drilling Studies in Thermal Regimes

    SciTech Connect

    Kolstad, George A.; Rowley, John C.

    1987-01-16

    This report is the proceedings of a workshop. The primary thrust of these discussion was to identify the major key technology barriers to the Department of Energy (DOE) supported Thermal Regimes CSD projects and to set priorities for research and development. The major technological challenge is the high temperature to be encountered at depth. Specific problems derived from this issue were widely recognized among the participants and are reflected in this summary. A major concern for the projected Thermal Regimes CSD boreholes was the technology required for continuous coring, in contrast to that required for drilling without core or spot coring. Current commercial technology bases for these two techniques are quite different. The DOE has successfully fielded projects that used both technologies, i.e, shallow continuous coring (Inyo Domes and Valles Caldera) and deeper drilling with spot cores (Imperial Valley-SSSDP). It was concluded that future scientific objectives may still require both approaches, but continuous coring is the most likely requirement in the near term. (DJE-2005)

  13. A Hydrogen Containment Process For Nuclear Thermal Engine Ground Testing

    NASA Technical Reports Server (NTRS)

    Wang, Ten-See; Stewart, Eric; Canabal, Francisco

    2016-01-01

    A hydrogen containment process was proposed for ground testing of a nuclear thermal engine. The hydrogen exhaust from the engine is contained in two unit operations: an oxygen-rich burner and a tubular heat exchanger. The burner burns off the majority of the hydrogen, and the remaining hydrogen is removed in the tubular heat exchanger through the species recombination mechanism. A multi-dimensional, pressure-based multiphase computational fluid dynamics methodology was used to conceptually sizing the oxygen-rich burner, while a one-dimensional thermal analysis methodology was used to conceptually sizing the heat exchanger. Subsequently, a steady-state operation of the entire hydrogen containment process, from pressure vessel, through nozzle, diffuser, burner and heat exchanger, was simulated numerically, with the afore-mentioned computational fluid dynamics methodology. The computational results show that 99% of hydrogen reduction is achieved at the end of the burner, and the rest of the hydrogen is removed to a trivial level in the heat exchanger. The computed flammability at the exit of the heat exchanger is less than the lower flammability limit, confirming the hydrogen containment capability of the proposed process.

  14. Surge current and electron swarm tunnel tests of thermal blanket and ground strap materials

    NASA Technical Reports Server (NTRS)

    Hoffmaster, D. K.; Inouye, G. T.; Sellen, J. M., Jr.

    1977-01-01

    The results are described of a series of current conduction tests with a thermal control blanket to which grounding straps have been attached. The material and the ground strap attachment procedure are described. The current conduction tests consisted of a surge current examination of the ground strap and a dilute flow, energetic electron deposition and transport through the bulk of the insulating film of this thermal blanket material. Both of these test procedures were used previously with thermal control blanket materials.

  15. Few genetic and environmental correlations between life history and stress resistance traits affect adaptation to fluctuating thermal regimes.

    PubMed

    Manenti, T; Sørensen, J G; Moghadam, N N; Loeschcke, V

    2016-09-01

    Laboratory selection in thermal regimes that differed in the amplitude and the predictability of daily fluctuations had a marked effect on stress resistance and life history traits in Drosophila simulans. The observed evolutionary changes are expected to be the result of both direct and correlated responses to selection. Thus, a given trait might not evolve independently from other traits because of genetic correlations among these traits. Moreover, different test environments can induce novel genetic correlations because of the activation of environmentally dependent genes. To test whether and how genetic correlations among stress resistance and life history traits constrain evolutionary adaptation, we used three populations of D. simulans selected for 20 generations in constant, predictable and unpredictable daily fluctuating thermal regimes and tested each of these selected populations in the same three thermal regimes. We explored the relationship between genetic correlations between traits and the evolutionary potential of D. simulans by comparing genetic correlation matrices in flies selected and tested in different thermal test regimes. We observed genetic correlations mainly between productivity, body size, starvation and desiccation tolerance, suggesting that adaptation to the three thermal regimes was affected by correlations between these traits. We also found that the correlations between some traits such as body size and productivity or starvation tolerance and productivity were determined by test regime rather than selection regime that is expected to limit genetic adaptation to thermal regimes in these traits. The results of this study suggest that several traits and several environments are needed to explore adaptive responses, as genetic and environmentally induced correlations between traits as results obtained in one environment cannot be used to predict the response of the same population in another environment. PMID:27273321

  16. Descriptors of natural thermal regimes in streams and their responsiveness to change in the Pacific Northwest of North America

    USGS Publications Warehouse

    Arismendi, Ivan; Johnson, Sherri L.; Dunham, Jason B.; Haggerty, Roy

    2013-01-01

    1. Temperature is a major driver of ecological processes in stream ecosystems, yet the dynamics of thermal regimes remain poorly described. Most work has focused on relatively simple descriptors that fail to capture the full range of conditions that characterise thermal regimes of streams across seasons or throughout the year. 2. To more completely describe thermal regimes, we developed several descriptors of magnitude, variability, frequency, duration and timing of thermal events throughout a year. We evaluated how these descriptors change over time using long-term (1979–2009), continuous temperature data from five relatively undisturbed cold-water streams in western Oregon, U.S.A. In addition to trends for each descriptor, we evaluated similarities among them, as well as patterns of spatial coherence, and temporal synchrony. 3. Using different groups of descriptors, we were able to more fully capture distinct aspects of the full range of variability in thermal regimes across space and time. A subset of descriptors showed both higher coherence and synchrony and, thus, an appropriate level of responsiveness to examine evidence of regional climatic influences on thermal regimes. Most notably, daily minimum values during winter–spring were the most responsive descriptors to potential climatic influences. 4. Overall, thermal regimes in streams we studied showed high frequency and low variability of cold temperatures during the cold-water period in winter and spring, and high frequency and high variability of warm temperatures during the warm-water period in summer and autumn. The cold and warm periods differed in the distribution of events with a higher frequency and longer duration of warm events in summer than cold events in winter. The cold period exhibited lower variability in the duration of events, but showed more variability in timing. 5. In conclusion, our results highlight the importance of a year-round perspective in identifying the most responsive

  17. Thermal and water regime of green roof segments filled with Technosol

    NASA Astrophysics Data System (ADS)

    Jelínková, Vladimíra; Šácha, Jan; Dohnal, Michal; Skala, Vojtěch

    2016-04-01

    Artificial soil systems and structures comprise appreciable part of the urban areas and are considered to be perspective for number of reasons. One of the most important lies in contribution of green roofs and facades to the heat island effect mitigation, air quality improvement, storm water reduction, etc. The aim of the presented study is to evaluate thermal and water regime of the anthropogenic soil systems during the first months of the construction life cycle. Green roof test segments filled with two different anthropogenic soils were built to investigate the benefits of such systems in the temperate climate. Temperature and water balance measurements complemented with meteorological observations and knowledge of physical properties of the soil substrates provided basis for detailed analysis of thermal and hydrological regime. Water balance of green roof segments was calculated for available vegetation seasons and individual rainfall events. On the basis of an analysis of individual rainfall events rainfall-runoff dependency was found for green roof segments. The difference between measured actual evapotranspiration and calculated potential evapotranspiration was discussed on period with contrasting conditions in terms of the moisture stress. Thermal characteristics of soil substrates resulted in highly contrasting diurnal variation of soils temperatures. Green roof systems under study were able to reduce heat load of the roof construction when comparing with a concrete roof construction. Similarly, received rainfall was significantly reduced. The extent of the rainfall reduction mainly depends on soil, vegetation status and experienced weather patterns. The research was realized as a part of the University Centre for Energy Efficient Buildings supported by the EU and with financial support from the Czech Science Foundation under project number 14-10455P.

  18. The Influence of Seasonal Climatic Parameters on the Permafrost Thermal Regime in West Siberia

    NASA Astrophysics Data System (ADS)

    Popova, V. V.; Shmakin, A. B.

    2009-12-01

    Statistical correlations between seasonal air temperatures and snow depths and active layer depths and permafrost temperatures were analyzed for tundra (Marre-Salle) and northern taiga (Nadym) sites in Western Siberia. Interannual variations in active layer depth in the tundra zone correlated with the average air temperature of the current summer, and in peatland and humid tundra, also with summer temperatures of the preceding 1-2 years. In the northern taiga zone, the active layer depth related to current summer air temperature and to a lesser extent, to spring and/or winter air temperatures. Variations in summer permafrost temperatures at 5-10m depth were correlated with spring air temperatures in the current and preceding 1-2 years. The weather regime during the preceding 1-2 years, therefore, reinforced or weakened ground temperature variations in a given year. Overall, the most important factors influencing the permafrost regime were spring and summer air temperatures, and in one case snow depth. However, statistical links between meteorological and permafrost parameters varied between the tundra and northern taiga zones and among landscape types within each zone, emphasizing the importance of analyses at short temporal scales and for individual terrain units.

  19. Thermal ground water flow systems in the thrust zone in southeastern Idaho

    SciTech Connect

    Ralston, D.R.

    1983-05-01

    The results of a regional study of thermal and non-thermal ground water flow systems in the thrust zone of southern Idaho and western Wyoming are presented. The study involved hydrogeologic and hydrochemical data collection and interpretation. Particular emphasis was placed on analyzing the role that thrust zones play in controlling the movement of thermal and non-thermal fluids.

  20. Thermal regime of the Escalante Desert, Utah, with an analysis of the the Newcastle Geothermal System

    SciTech Connect

    Chapman, D.S.; Clement, M.D.; Mase, C.W.

    1981-12-10

    Twenty-five new heat flow measurements are presented for the Escalante Desert region within the Great Basin of the wester United States. Heat flow, excluding geothermal areas, ranges from 43 to 350 mW m/sup -2/, but much of the variability may be caused by deeply circulating groundwater redistributing the regional flux. A subset of 10 sites drilled specifically to characterize the heat flow of the region yielded a mean of 100 mW m/sup -2/ with a standard deviation of 22 mW m/sup -2/. A comparison of thermal conductivities of solid cylindrical discs and rock chips (rhyolite to andesite tuffs) confirmed the importance of porosity corrections to thermal conductivity measurements. A 'blind' geothermal system southwest of Newastle, Utah, situated within the Escalante Desert, has also been studied. Temperature Desert, has also been studied. Temperatures of 110/sup 0/C are observed only 75 m below the ground surface. Heat flow results from 11 drillholes in this region yield values between 163 and 3065 mW m/sup -2/. The 500 mW m/sup -2/ contour encloses an area of 9.4 km/sup 2/. By integrating the excess heat flux (above background) over the thermal anomaly, we deduce a thermal power loss of 12.8 MW for this geothermal system, which corresponds to a subsurface water discharge of 32 kg s/sup -1/.

  1. Thermal and dynamical regimes of single- and two-phase magmatic flow in dikes

    NASA Technical Reports Server (NTRS)

    Carrigan, Charles R.; Schubert, Gerald; Eichelberger, John C.

    1992-01-01

    The coupling between thermal and dynamical regimes of single- and two-phase magmatic flow in dikes, due to temperature-dependent viscosity and dissipation, was investigated using finite element calculations of magma flow in dikelike channels with length-to-width ratios of 1000:1 or more. Solutions of the steady state equations governing magma flow are obtained for a variety of conditions ranging from idealized plane-parallel models to cases involving nonparallel geometry and two-phase flows. The implications of the numerical simulations for the dynamics of flow in a dike-reservoir system and the consequences of dike entrance conditions on magmatic storage are discussed. Consideration is also given to an unmixing/self-lubrication mechanism which may be important for the lubrication of silicic magmas rising to the earth's surface in mixed magma ascent scenarios, which naturally segregates magma mixtures of two components with differing viscosities to minimize the driving pressure gradient.

  2. Thermal and dynamical regimes of single- and two-phase magmatic flow in dikes

    SciTech Connect

    Carrigan, C. .; Schubert, G.; Eichelberger, J.C. California Univ., Los Angeles Alaska Univ., Fairbanks )

    1992-11-01

    The coupling between thermal and dynamical regimes of single- and two-phase magmatic flow in dikes, due to temperature-dependent viscosity and dissipation, was investigated using finite element calculations of magma flow in dikelike channels with length-to-width ratios of 1000:1 or more. Solutions of the steady state equations governing magma flow are obtained for a variety of conditions ranging from idealized plane-parallel models to cases involving nonparallel geometry and two-phase flows. The implications of the numerical simulations for the dynamics of flow in a dike-reservoir system and the consequences of dike entrance conditions on magmatic storage are discussed. Consideration is also given to an unmixing/self-lubrication mechanism which may be important for the lubrication of silicic magmas rising to the earth's surface in mixed magma ascent scenarios, which naturally segregates magma mixtures of two components with differing viscosities to minimize the driving pressure gradient. 56 refs.

  3. Effect of tidal regime on the thermal tolerance of the marine gastropod Lunella smaragda (Gmelin 1791).

    PubMed

    Mortensen, B J D; Dunphy, B J

    2016-08-01

    The tidal cycle around New Zealand results in spring low tides consistently occurring during the hottest part of the day (mid-afternoon) in north-eastern New Zealand, and during the cooler dawn/dusk periods in the north-west of the country. We hypothesised that due to mid-afternoon spring low tides, intertidal populations residing at north-eastern sites would show greater thermotolerance than their north-west conspecifics. To test this we used the marine gastropod, Lunella smaragda, which were collected from sites on both the East and West coasts of the Auckland region and exposed to an acute heat shock. Thermotolerance was measured as survivorship (LT50), drop down time (time to heat coma) and thermal stability of the anaerobic energy producing enzyme Tauropine dehydrogenase. Furthermore, temperature loggers were deployed at each site so as to record and compare thermal regimes among sites. A strong temperature spike associated with spring low tide was found at all sites, and maximal temperatures of all East coast sites were higher than West coast sites (in some case by up to 10°C). In terms of thermotolerance, mortality of L. smaragda occurred at 42°C leading to 100% mortality at 45°C. However, comparison of LT50 showed snails were equally thermotolerant regardless of site of collection. Similar results were found in TDH thermal stability with animals from all sites showing an approximately 80% decrease in enzyme activity after 10min exposure to 42°C. Whilst drop down times were different among sites these were correlated with animal size as opposed to site of collection. Thus, East coast populations of L. smaragda appear no more thermotolerant than their West coast counterparts. Such a result is concerning as maximal temperatures at East coast sites already exceed the LT50 values of L. smaragda recorded in the lab suggesting these populations have less of a thermal safety margin. PMID:27503732

  4. Ground coupling and single-blow thermal storage in a double-envelope house

    NASA Astrophysics Data System (ADS)

    Ghaffari, H. T.; Jones, R. F.

    1981-04-01

    The possibility of ground thermal storage and coupling in a double shell house was investigated. Temperature distribution in the ground, utilization of measured ground temperatures, and the amount of heat retrieval are assessed. One experimental model and several hypothetical models are introduced, and their affects and advantages are compared.

  5. Ground coupling and single-blow thermal storage in a double-envelope house

    SciTech Connect

    Ghaffari, H T; Jones, R F

    1981-01-01

    The possibility of ground thermal storage and coupling in a double-shell house is investigated. Temperature distribution in the ground, utilizing measured ground temperatures, is obtained, and the amount of heat retrieval is assessed. One experimental model and several hypothetical models are introduced; their effects and advantages are compared.

  6. Response of stream invertebrates to a global-warming thermal regime: An ecosystem-level manipulation

    SciTech Connect

    Hogg, I.D.; Williams, D.D.

    1996-03-01

    We manipulated, in accord with global-warming predictions, the thermal regime of a permanent first-order stream near Toronto, Ontario, Canada. We examined the effects of a 2-3.5{degrees}C water-temperature increase on densities, biomass, species composition, and life histories of resident stream invertebrates. The stream was divided longitudinally at the source into two channels, one control and one experimental, and a before and after (BACI) design was employed such that one pre-manipulation year was followed by 2 yr of the temperature manipulation. Changes in the experimental channel following commencement of the manipulation included: (1) decreased total animal densities, particularly Chironomidae (Diptera); (2) earlier onset of adult insect emergence; (3) increased growth rates and precocious breeding in Hyallella azteca (Amphipoda); (4) smaller size at maturity for Nemoura trispinosa (Plecoptera) and H., azteca and (5) altered sex ratios for Lepidostoma vernale (Trichoptera). These results partially corroborate previous laboratory and field studies. However, variation in the responses of individual target species to the manipulation was unexpected and may have been influenced by the genetic structure of local populations. We conclude that levels of gene flow among habitats may be critical to the degree of impact seen as a result of large-scale thermal perturbation (e.g., global warming). 60 refs., 13 figs., 1 tab.

  7. A Ground-Nesting Galliform’s Response to Thermal Heterogeneity: Implications for Ground-Dwelling Birds

    PubMed Central

    Carroll, J. Matthew; Davis, Craig A.; Elmore, R. Dwayne; Fuhlendorf, Samuel D.

    2015-01-01

    The habitat selection choices that individuals make in response to thermal environments influence both survival and reproduction. Importantly, the way that organisms behaviorally respond to thermal environments depends on the availability and juxtaposition of sites affording tolerable or preferred microclimates. Although, ground nesting birds are especially susceptible to heat extremes across many reproductive stages (i.e., breeding, nesting, brood rearing), the mechanistic drivers of nest site selection for these species are not well established from a thermal perspective. Our goal was to assess nest site selection relative to the configuration of the thermal landscape by quantifying thermal environments available to a ground-nesting bird species inhabiting a climatically stressful environment. Using northern bobwhite (Colinus virginanus) as a model species, we measured black bulb temperature (Tbb) and vegetation parameters at 87 nests, 87 paired sites and 205 random landscape sites in Western Oklahoma during spring and summer 2013 and 2014. We found that thermal space within the study area exhibited differences in Tbb of up to 40°C during peak diurnal heating, resulting in a diverse thermal landscape available to ground-nesting birds. Within this thermally heterogeneous landscape, nest sites moderated Tbb by more than 12°C compared to random landscape sites. Furthermore, successful nests remained on average 6°C cooler than unsuccessful nests on days experiencing ambient temperatures ≥ 39°C. Models of future Tbb associated with 2080 climate change projections indicate that nesting bobwhites will face substantially greater Tbb throughout the landscape for longer durations, placing an even greater importance on thermal choices for nest sites in the future. These results highlight the capacity of landscape features to act as moderators of thermal extremes and demonstrate how thermal complexity at organism-specific scales can dictate habitat selection. PMID

  8. Unmanned Ground Vehicle Perception Using Thermal Infrared Cameras

    NASA Technical Reports Server (NTRS)

    Rankin, Arturo; Huertas, Andres; Matthies, Larry; Bajracharya, Max; Assad, Christopher; Brennan, Shane; Bellutta, Paolo; Sherwin, Gary W.

    2011-01-01

    The ability to perform off-road autonomous navigation at any time of day or night is a requirement for some unmanned ground vehicle (UGV) programs. Because there are times when it is desirable for military UGVs to operate without emitting strong, detectable electromagnetic signals, a passive only terrain perception mode of operation is also often a requirement. Thermal infrared (TIR) cameras can be used to provide day and night passive terrain perception. TIR cameras have a detector sensitive to either mid-wave infrared (MWIR) radiation (3-5?m) or long-wave infrared (LWIR) radiation (8-12?m). With the recent emergence of high-quality uncooled LWIR cameras, TIR cameras have become viable passive perception options for some UGV programs. The Jet Propulsion Laboratory (JPL) has used a stereo pair of TIR cameras under several UGV programs to perform stereo ranging, terrain mapping, tree-trunk detection, pedestrian detection, negative obstacle detection, and water detection based on object reflections. In addition, we have evaluated stereo range data at a variety of UGV speeds, evaluated dual-band TIR classification of soil, vegetation, and rock terrain types, analyzed 24 hour water and 12 hour mud TIR imagery, and analyzed TIR imagery for hazard detection through smoke. Since TIR cameras do not currently provide the resolution available from megapixel color cameras, a UGV's daytime safe speed is often reduced when using TIR instead of color cameras. In this paper, we summarize the UGV terrain perception work JPL has performed with TIR cameras over the last decade and describe a calibration target developed by General Dynamics Robotic Systems (GDRS) for TIR cameras and other sensors.

  9. Unmanned ground vehicle perception using thermal infrared cameras

    NASA Astrophysics Data System (ADS)

    Rankin, Arturo; Huertas, Andres; Matthies, Larry; Bajracharya, Max; Assad, Christopher; Brennan, Shane; Bellutta, Paolo; Sherwin, Gary W.

    2011-05-01

    The ability to perform off-road autonomous navigation at any time of day or night is a requirement for some unmanned ground vehicle (UGV) programs. Because there are times when it is desirable for military UGVs to operate without emitting strong, detectable electromagnetic signals, a passive only terrain perception mode of operation is also often a requirement. Thermal infrared (TIR) cameras can be used to provide day and night passive terrain perception. TIR cameras have a detector sensitive to either mid-wave infrared (MWIR) radiation (3-5μm) or long-wave infrared (LWIR) radiation (7-14μm). With the recent emergence of high-quality uncooled LWIR cameras, TIR cameras have become viable passive perception options for some UGV programs. The Jet Propulsion Laboratory (JPL) has used a stereo pair of TIR cameras under several UGV programs to perform stereo ranging, terrain mapping, tree-trunk detection, pedestrian detection, negative obstacle detection, and water detection based on object reflections. In addition, we have evaluated stereo range data at a variety of UGV speeds, evaluated dual-band TIR classification of soil, vegetation, and rock terrain types, analyzed 24 hour water and 12 hour mud TIR imagery, and analyzed TIR imagery for hazard detection through smoke. Since TIR cameras do not currently provide the resolution available from megapixel color cameras, a UGV's daytime safe speed is often reduced when using TIR instead of color cameras. In this paper, we summarize the UGV terrain perception work JPL has performed with TIR cameras over the last decade and describe a calibration target developed by General Dynamics Robotic Systems (GDRS) for TIR cameras and other sensors.

  10. The thermal regime of abandoned channels: a preliminary analysis towards a water temperature model for the Allier River, France

    NASA Astrophysics Data System (ADS)

    Casado, Ana; Peiry, Jean-Luc

    2014-05-01

    The growing recognition of the ecological and water quality significance of river water temperature led to a large number of studies assessing thermal processes in streams and rivers. Yet, thermal processes in abandoned channels, which play an important role in maintaining water quality and biological diversity in fluvial corridors, have received minor attention. This study evaluates water temperature regimes in three abandoned channels of the Allier River, France, and quantifies the regime sensitivity to climatic (air temperature) and hydrological (surface and subsurface flow) influence. Analysis was conducted at annual and daily scales, and at two distinct sections of each abandoned channel: (i) the downstream section, which is well connected to the main stream channel, and (ii) the upstream section, which is poorly connected to the main stream channel and hence subject to greater influence of subsurface flow. Annual and daily water temperature regimes for all channels and sections were classified based on relative differences in the 'shape' (timing) and the 'magnitude' (size) of the thermographs. The climatic and hydrological sensitivity of water temperature regimes was quantified using a Sensitivity Index. Analysis at the annual scale revealed relative similarity in patterns of thermal response over time, with clear differentiation between upstream and downstream channel sections in all sites. Water temperature regimes in the upstream channel sections were strongly linked to subsurface water temperature in terms of both timing and size of the annual thermograph; water temperature regimes in the downstream channel sections were more sensitive to air and river water temperature, especially regarding the timing of the annual regimes. Although annual regimes of water temperature exhibited distinct patterns that were similar across sites and over time, analysis of daily water temperature regimes revealed broad differences within and between sites. Day

  11. Enhanced thermal radiation in terahertz and far-infrared regime by hot phonon excitation in a field effect transistor

    SciTech Connect

    Chung, Pei-Kang; Yen, Shun-Tung

    2014-11-14

    We demonstrate the hot phonon effect on thermal radiation in the terahertz and far-infrared regime. A pseudomorphic high electron mobility transistor is used for efficiently exciting hot phonons. Boosting the hot phonon population can enhance the efficiency of thermal radiation. The transistor can yield at least a radiation power of 13 μW and a power conversion efficiency higher than a resistor by more than 20%.

  12. Effects of constant and cyclical thermal regimes on growth and feeding of juvenile cutthroat trout of variable sizes

    USGS Publications Warehouse

    Meeuwig, M.H.; Dunham, J.B.; Hayes, J.P.; Vinyard, G.L.

    2004-01-01

    The effects of constant (12, 18, and 24 A?C) and cyclical (daily variation of 15a??21 and 12a??24 A?C) thermal regimes on the growth and feeding of Lahontan cutthroat trout (Oncorhynchus clarki henshawi) of variable sizes were examined. Higher constant temperatures (i.e., 24 A?C) and more variable daily temperatures (i.e., 12a??24 A?C daily cycle) negatively affected growth rates. As fish mass increased (from 0.24 to 15.52 g) the effects of different thermal regimes on mass growth became more pronounced. Following 14 days exposure to the thermal regimes, feeding rates of individual fish were assessed during acute exposure (40 min) to test temperatures of 12, 18, and 24 A?C. Feeding rate was depressed during acute exposure to 24 A?C, but was not significantly affected by the preceding thermal regime. Our results indicate that even brief daily exposure to higher temperatures (e.g., 24 A?C) can have considerable sublethal effects on cutthroat trout, and that fish size should be considered when examining the effects of temperature.

  13. Soil thermal regime and geomorphogenesis at Fuentes Carrionas massif (Cantabrian Range, NW Iberian Peninsula).

    NASA Astrophysics Data System (ADS)

    Pellitero, Ramon; Serrano Cañadas, Enrique

    2015-04-01

    Fuentes Carrionas is a massif within the Cantabrian Range, in NW Iberian Peninsula. Its altitude ranges between 1400 and 2500 meters and its climate is an oceanic/Mediterranean transition one, with cold temperatures and heavy snowfall in the winter/early spring season, and a warm and dry summer season. Due to its outstanding altitude and lithological variety in the Cantabrian Range context, Fuentes Carrionas holds some periglacial activity (gelifluction, frost shattering) which is absent elsewhere in NW Iberian Peninsula. This work is relates the soil thermal regime across the mountain gradient to landforms formation. 14 thermometers (11 i-button, protected in a plastic can, and three UTL data loggers) were buried at a shallow depth (10 cm.) between autumn 2009 and summer 2012. 12 thermometers were placed between 1900 and 2400 m.a.s.l. at 250 meters altitude interval at the four main aspects. Two additional thermometers were place in the Curavacas N face for permafrost identification. Thermometers were calibrated to yield a measurement every 6 hours starting from 8 AM during one year's time. Data was collected annually in the summer season. Some additional soil temperature data was obtained from an external project in the same area for the 2007-2009 interval. In this case thermometers were "Hobbo" model, and they were also buried to a shallow depth. Results show a permafrost free mountain range. Annual average soil temperatures range between 1 and 8 degrees Celsius. Snow pack appears as a decisive factor in winter temperatures, as the zero curtain effect can be tracked in many cases. Snow cover patterns show a distinctive behavior between S and N aspects, with a 3 months snow cover on the southern faces and between 6 and 9 at the northern analogues. This cover has a relevant impact on geomorphological processes. There is a clear relation between spring snow melt and solifluction or channelized erosion. Also, snow cover prevents the occurrence of freeze/thaw cycles

  14. Hydrology and geochemistry of thermal ground water in southwestern Idaho and north-central Nevada

    SciTech Connect

    Young, H.W.; Lewis, R.E.

    1980-12-01

    The study area occupies about 14,500 square miles in southwestern Idaho and north-central Nevada. Thermal ground water occurs under artesian conditions, in discontinuous or compartmented zones, in igneous or sedimentary rocks of Tertiary age. Ground-water movement is generally northward. Temperatures of the ground water range from about 30/sup 0/ to more than 80/sup 0/C. Chemical analyses of water from 12 wells and 9 springs indicate that nonthermal waters are a calcium bicarbonate type; thermal waters are a sodium bicarbonate type. Chemical geothermometers indicate probable maximum reservoir temperatures are near 100/sup 0/C. Concentration of tritium in the thermal water water is near zero.

  15. The mantle wedge's transient 3-D flow regime and thermal structure

    NASA Astrophysics Data System (ADS)

    Davies, D. R.; Le Voci, G.; Goes, S.; Kramer, S. C.; Wilson, C. R.

    2016-01-01

    Arc volcanism, volatile cycling, mineralization, and continental crust formation are likely regulated by the mantle wedge's flow regime and thermal structure. Wedge flow is often assumed to follow a regular corner-flow pattern. However, studies that incorporate a hydrated rheology and thermal buoyancy predict internal small-scale-convection (SSC). Here, we systematically explore mantle-wedge dynamics in 3-D simulations. We find that longitudinal "Richter-rolls" of SSC (with trench-perpendicular axes) commonly occur if wedge hydration reduces viscosities to Pa s, although transient transverse rolls (with trench-parallel axes) can dominate at viscosities of Pa s. Rolls below the arc and back arc differ. Subarc rolls have similar trench-parallel and trench-perpendicular dimensions of 100-150 km and evolve on a 1-5 Myr time-scale. Subback-arc instabilities, on the other hand, coalesce into elongated sheets, usually with a preferential trench-perpendicular alignment, display a wavelength of 150-400 km and vary on a 5-10 Myr time scale. The modulating influence of subback-arc ridges on the subarc system increases with stronger wedge hydration, higher subduction velocity, and thicker upper plates. We find that trench-parallel averages of wedge velocities and temperature are consistent with those predicted in 2-D models. However, lithospheric thinning through SSC is somewhat enhanced in 3-D, thus expanding hydrous melting regions and shifting dehydration boundaries. Subarc Richter-rolls generate time-dependent trench-parallel temperature variations of up to K, which exceed the transient 50-100 K variations predicted in 2-D and may contribute to arc-volcano spacing and the variable seismic velocity structures imaged beneath some arcs.

  16. Regional warming and the thermal regimes of American crocodile nests in the Tempisque Basin, Costa Rica.

    PubMed

    Murray, Christopher M; Easter, Michael; Padilla, Sergio; Marin, Mahmood Sasa; Guyer, Craig

    2016-08-01

    Spatial variation in global climate change makes population-specific responses to this enigmatic threat pertinent on a regional scale. Organisms with temperature-dependent sex determination (TSD) potentially possess a unique physiological susceptibility that threatens population viability if rapid environmental effects on sex ratios render populations non-viable. A heavily male-biased sex ratio for hatchling American crocodiles of the Tempisque Basin, Costa Rica requires assessment of how nest temperature affects sex determination at this site, how females might compensate for these effects when creating nests, and how current patterns of climate change might alter future sex ratios and survival in hatchling cohorts. We demonstrate high within-nest variation in temperature but predict a female bias at hatching based on nest temperatures quantified here. Further, our data suggest that egg size and metabolic heating associated with this factor outweighs microhabitat parameters and depth in influencing nest thermal regimes. Finally, we document regional warming in the Tempisque Basin over the last 15 years and project that further heating over the next 15 years will not yield hatchling sex ratios as male biased as those currently found at this site. Thus, we find no support for nest temperature or climate change as likely explanations for male-biased American crocodile (Crocodylus acutus) sex ratios in the Tempisque Basin. PMID:27503716

  17. Thermal regime of dune-covered sediments under gaining and losing water bodies

    NASA Astrophysics Data System (ADS)

    Cardenas, M. Bayani; Wilson, John L.

    2007-12-01

    We investigate the effects of current-bed form induced flow and heat transport through permeable-bottom sediments overlain by a marine or terrestrial water column that is gaining or losing deep groundwater. Heat transport is forced by the diel variation of temperature in the water column. The investigation utilizes sequentially coupled simulations of turbulent flow in the water column, and Darcy flow and heat transport in the sediments. The simulations address the question when, where, and by how much are diel water column temperature variations transmitted into sediments subjected to ambient-groundwater discharge? This is crucial information for detecting, observing, and predicting temperature-sensitive biogeochemical and ecological processes in the bottom sediments. When the groundwater gain or loss is small, it has no appreciable effect on temperatures in the sediments, which are controlled by heat conduction and current-bed form induced heat advection. As losing discharge increases, the temperature signal from the water column penetrates deeper into the sediments, with the largest temperature variations found under a downwelling zone along the stoss side of the bed form and damped temperature variations found near a narrow upwelling zone below the crest. Similar patterns are observed under gaining conditions, but with temperature variations penetrating to shallower depths; the interfacial exchange zone is diminished by upward movement of deep groundwater. Large gains or losses of deep groundwater prevent the formation of an interfacial exchange zone making heat transport almost vertically one-dimensional. The sensitivity of the sediment-thermal regime to hydrodynamic conditions increases with increasing water column current (Reynolds number) and with sediment permeability.

  18. Fluid Origins, Thermal Regimes, and Fluid and Solute Fluxes in the Forearc of Subduction Zones

    NASA Astrophysics Data System (ADS)

    Kastner, M.; Solomon, E. A.; Harris, R. N.; Torres, M. E.

    2014-12-01

    An in-depth analysis and synthesis of published and newly acquired data on the chemical and isotopic composition of forearc fluids, fluid fluxes, and the associated thermal regimes in five well-studied, representative erosional and accretionary subduction zone (SZ) forearcs will be presented. Evidence of large-scale fluid flow, primarily focused along faults, is manifested by widespread seafloor venting, associated biological communities, authigenic carbonate formation, chemical and isotopic anomalies in pore-fluid depth-profiles, and thermal anomalies. The nature of fluid venting seems to differ at the two types of SZs. At both, fluid and gas venting sites are primarily associated with faults. At accretionary SZs, the décollement and underthrust coarser-grained stratigraphic horizons are the main fluid conduits, whereas at non-accreting and erosive margins, the fluids from compaction and dehydration reactions are to a great extent partitioned between the décollement and focused conduits through the prism. The measured fluid output fluxes at seeps are high, ~15-40 times the amount that can be produced through local steady-state compaction, suggesting additional fluid sources or non-steady-state fluid flow must be involved. Recirculation of seawater must be an important component of the overall forearc output fluid flux. The most significant chemical and isotopic characteristics of the expelled fluids relative to seawater are: Cl dilution, sulfate, Ca and Mg depletions, and enrichments in Li, B, Si, Sr, alkalinity, and hydrocarbon concentrations; they often have distinctive δ18O, δD, δ7Li, δ11B, and δ37Cl values, and variable Sr isotope ratios. These characteristics provide key insights on the source of the fluid and the temperature at the source. Using our best fluid output flux estimate and considering an ocean volume of 1340 × 106 km3, the global ocean residence time in SZs is ~100 Myr. This value is five times faster than previous estimates for SZs and

  19. ETR, TRA642. ON GROUND FLOOR. WITH OUTER THERMAL RING IN ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    ETR, TRA-642. ON GROUND FLOOR. WITH OUTER THERMAL RING IN PLACE AND CONDUIT PRESERVED, HIGH-DENSITY CONCRETE IS PLACED BETWEEN THE THERMAL RING AND THE OUTER REACTOR FORM. INL NEGATIVE NO. 56-2400. Jack L. Anderson, Photographer, 6/10/1956 - Idaho National Engineering Laboratory, Test Reactor Area, Materials & Engineering Test Reactors, Scoville, Butte County, ID

  20. Modeling the spatio-temporal variability in subsurface thermal regimes across a low-relief polygonal tundra landscape: Modeling Archive

    DOE Data Explorer

    Peter E. Thornton; Jitendra Kumar; Colleen M. Iversen; Richard T. Mills; Gautam Bisht; Nathan Collier; Vladimir Romanovsky

    2016-01-27

    This Modeling Archive is in support of an NGEE Arctic discussion paper under review and available at http://www.the-cryosphere-discuss.net/tc-2016-29/. Vast carbon stocks stored in permafrost soils of Arctic tundra are under risk of release to atmosphere under warming climate. Ice--wedge polygons in the low-gradient polygonal tundra create a complex mosaic of microtopographic features. The microtopography plays a critical role in regulating the fine scale variability in thermal and hydrological regimes in the polygonal tundra landscape underlain by continuous permafrost. Modeling of thermal regimes of this sensitive ecosystem is essential for understanding the landscape behaviour under current as well as changing climate. We present here an end-to-end effort for high resolution numerical modeling of thermal hydrology at real-world field sites, utilizing the best available data to characterize and parameterize the models. We develop approaches to model the thermal hydrology of polygonal tundra and apply them at four study sites at Barrow, Alaska spanning across low to transitional to high-centered polygon and representative of broad polygonal tundra landscape. A multi--phase subsurface thermal hydrology model (PFLOTRAN) was developed and applied to study the thermal regimes at four sites. Using high resolution LiDAR DEM, microtopographic features of the landscape were characterized and represented in the high resolution model mesh. Best available soil data from field observations and literature was utilized to represent the complex hetogeneous subsurface in the numerical model. This data collection provides the complete set of input files, forcing data sets and computational meshes for simulations using PFLOTRAN for four sites at Barrow Environmental Observatory. It also document the complete computational workflow for this modeling study to allow verification, reproducibility and follow up studies.

  1. The dynamics of thermal regime changes of a local working zone in conditions of its heating by gas infrared radiators

    NASA Astrophysics Data System (ADS)

    Nee, A.

    2015-10-01

    Mathematical modeling of unsteady heat transfer in a closed rectangular area with a local heat supply object in a conjugate formulation in working conditions of radiation source of energy is passed. Fields of temperatures and stream functions, illustrating the influence of a local typical object on thermal regime are received. The effect of Grashof number on dimensionless heat transfer coefficient - Nusselt number is investigated. The influence of nonconducted heat supply object on heat transfer rate in solution domain is showed.

  2. Third-order correlation function and ghost imaging of chaotic thermal light in the photon counting regime

    SciTech Connect

    Zhou Yu; Simon, Jason; Liu Jianbin; Shih, Yanhua

    2010-04-15

    In a near-field three-photon correlation measurement, we observed the third-order temporal and spatial correlation functions of chaotic thermal light in the single-photon counting regime. In the study, we found that the probability of jointly detecting three randomly radiated photons from a chaotic thermal source by three individual detectors is 6 times greater if the photodetection events fall in the coherence time and coherence area of the radiation field than if they do not. From the viewpoint of quantum mechanics, the observed phenomenon is the result of three-photon interference. By making use of this property, we measured the three-photon thermal light lensless ghost image of a double spot and achieved higher visibility compared with the two-photon thermal light ghost image.

  3. Influences on shallow ground temperatures in high flux thermal systems

    NASA Astrophysics Data System (ADS)

    Lubenow, Brady L.; Fairley, Jerry P.; Lindsey, Cary R.; Larson, Peter B.

    2016-09-01

    Ground temperature measurements are a useful indication of subsurface processes and heat flux, particularly in volcanic and hydrothermal systems, but obtaining reliable data at sufficient resolution can be difficult. Investigators commonly use temperature measurements at 1 m depths to minimize land surface boundary impacts; however, these measurements are time-consuming and invasive, limiting the number of points that can be surveyed. Alternatively, shallow ground temperature measurements (≤ 25 cm depth) offer a rapid and minimally-invasive way to collect a large number of observations in a target area. Although this method has obvious appeal, changing atmospheric conditions can impact the observed temperatures, and thus may reasonably be expected to influence interpretations arising from the data. Here we examine the impact of precipitation and changing air temperature on shallow ground temperatures in the vicinity of a group of hot springs located in Yellowstone National Park, Wyoming. We find that the mean, the range, and the skewness of the observed temperatures were decreased by changing atmospheric conditions; however, the model variogram representing data taken after several days of moderate precipitation adequately described the spatial correlation of data taken before precipitation. We therefore conclude that the ability to differentiate between high- and low-flux areas may be somewhat reduced by moderate precipitation and changing atmospheric conditions, but that interpretations made on the basis of characteristics of the inferred variograms are likely to be robust to such perturbations in high heat flux environments.

  4. Thermal Effects in the Hydrothermal Regime of Magmatic-Hydrothermal Systems

    NASA Astrophysics Data System (ADS)

    Candela, P. A.

    2002-05-01

    Models of conductive and convective cooling of epizonal magma bodies commonly show temperatures in the country rock that are at or below 500 C. Indeed, simple conductive cooling models place the contact temperature below the midpoint of the intrusion and country rock temperatures, which for felsic magmas in cold country rock (cf. Furlong et al., 1991, Rev. in Min. v. 26), is approximately 500 C or lower. However, some vein systems record temperatures e.g. from fluid inclusions or phase equilibria that exceed 500 C. In some cases, as in some deep skarn deposits, high temperatures of ore deposition probably result from high country rock temperatures. Veins may also occur in the already cooled portions of an ore-generative pluton, which can be at any temperature below the solidus. In still other cases, high country rock temperatures may be heated by previous magmatic events (thermal ground preparation). However, high temperatures of mineral alteration or deposition may be produced in initially cold country rock by flux of high temperature magmatic volatile phase from the magma itself. This is a likely explanation when ore is associated with early stages of magmatism at shallow levels in the crust. The mass conservation equations of infiltration theory (cf. Ferry, 1991, Rev. in Min. v. 26), can be used to estimate time-integrated fluid fluxes, q, given changes in quartz solubility with temperature, geothermal and geobaric gradients in shallow magmatic environments, and order of magnitude vein quartz densities in porphyry copper deposits. The change in the silica content of the rock due to quartz veining is then given by: \\Delta cQZ =- \\int Jw dt \\times \

  5. The role of snow cover in ground thermal conditions in three sites with contrasted topography in Sierra Nevada (Spain)

    NASA Astrophysics Data System (ADS)

    Oliva, Marc; Salvador, Ferran; Gómez Ortiz, Antonio; Salvà, Montserrat

    2014-05-01

    Snow cover has a high capacity to insulate the soil from the external thermal influences. In regions of high snowfall, such as the summit areas of the highest Iberian mountain ranges, the presence of a thick snow cover may condition the existence or inexistence of permafrost conditions. In order to analyze the impact of the thickness, duration and interannual variability of snow cover on the ground thermal regime in the massif of Sierra Nevada, we have analyzed soil temperatures at a depth of 2 cm for the period 2006-2012 in three sites of contrasting topography as well as air temperatures for the same period: (a) Corral del Veleta (3100 m) in a rock glacier located in the northern Veleta cirque, with high and persistent snow cover. (b) Collado de los Machos (3300 m), in a summit area with relict stone circles, with little snow accumulation due to wind effect. (c) Río Seco (3000 m), in a solifluction lobe located in this southern glacial cirque with moderate snowfall. Considering the air and 2 cm depth soil temperature records, the freezing degree-days were calculated for each year from November to May in order to characterize the role of snow as a thermal insulator of the ground during the cold season (Frauenfeld et al., 2007). In all cases, the highest values of freezing degree-days correspond to years with little snowfall (2006-2007, 2007-2008, 2011-2012), while in years with a thicker snow cover (2008-2009, 2009-2010, 2010-2011) the total freezing degree-days were significantly lower. The accumulation of freezing degree-days is maximum at the wind-exposed site of Collado de los Machos, where the wind redistributes snow and favours the penetration of cold into the ground. The opposite pattern occurs in the Veleta cirque, where most persistent snow cover conditions determine lower accumulated freezing degree-days than in Collado de los Machos and Rio Seco.

  6. Unmanned Ground Vehicle Perception Using Thermal Infrared Cameras

    NASA Technical Reports Server (NTRS)

    Rankin, Arturo; Huertas, Andres; Matthies, Larry; Bajracharya, Max; Assad, Christopher; Brennan, Shane; Bellut, Paolo; Sherwin, Gary

    2011-01-01

    TIR cameras can be used for day/night Unmanned Ground Vehicle (UGV) autonomous navigation when stealth is required. The quality of uncooled TIR cameras has significantly improved over the last decade, making them a viable option at low speed Limiting factors for stereo ranging with uncooled LWIR cameras are image blur and low texture scenes TIR perception capabilities JPL has explored includes: (1) single and dual band TIR terrain classification (2) obstacle detection (pedestrian, vehicle, tree trunks, ditches, and water) (3) perception thru obscurants

  7. Adaptation to local thermal regimes by crustose coralline algae does not affect rates of recruitment in coral larvae

    NASA Astrophysics Data System (ADS)

    Siboni, Nachshon; Abrego, David; Evenhuis, Christian; Logan, Murray; Motti, Cherie A.

    2015-12-01

    Crustose coralline algae (CCA) are well known for their ability to induce settlement in coral larvae. While their wide distribution spans reefs that differ substantially in temperature regimes, the extent of local adaptation to these regimes and the impact they have on CCA inductive ability are unknown. CCA Porolithon onkodes from Heron (southern) and Lizard (northern) islands on Australia's Great Barrier Reef (separated by 1181 km) were experimentally exposed to acute or prolonged thermal stress events and their thermal tolerance and recruitment capacity determined. A sudden onset bleaching model was developed to determine the health status of CCA based on the rate of change in the CCA live surface area (LSA). The interaction between location and temperature was significant ( F (2,119) = 6.74, p = 0.0017), indicating that thermally driven local adaptation had occurred. The southern population remained healthy after prolonged exposure to 28 °C and exhibited growth compared to the northern population ( p = 0.022), with its optimum temperature determined to be slightly below 28 °C. As expected, at the higher temperatures (30 and 32 °C) the Lizard Island population performed better that those from Heron Island, with an optimum temperature of 30 °C. Lizard Island CCA displayed the lowest bleaching rates at 30 °C, while levels consistently increased with temperature in their southern counterparts. The ability of those CCA deemed thermally tolerant (based on LSA) to induce Acropora millepora larval settlement was then assessed. While spatial differences influenced the health and bleaching levels of P. onkodes during prolonged and acute thermal exposure, thermally tolerant fragments, regardless of location, induced similar rates of coral larval settlement. This confirmed that recent thermal history does not influence the ability of CCA to induce settlement of A. millepora larvae.

  8. Estimation of lifespan and economy parameters of steam-turbine power units in thermal power plants using varying regimes

    NASA Astrophysics Data System (ADS)

    Aminov, R. Z.; Shkret, A. F.; Garievskii, M. V.

    2016-08-01

    The use of potent power units in thermal and nuclear power plants in order to regulate the loads results in intense wear of power generating equipment and reduction in cost efficiency of their operation. We review the methodology of a quantitative assessment of the lifespan and wear of steam-turbine power units and estimate the effect of various operation regimes upon their efficiency. To assess the power units' equipment wear, we suggest using the concept of a turbine's equivalent lifespan. We give calculation formulae and an example of calculation of the lifespan of a steam-turbine power unit for supercritical parameters of steam for different options of its loading. The equivalent lifespan exceeds the turbine's assigned lifespan only provided daily shutdown of the power unit during the night off-peak time. We obtained the engineering and economical indices of the power unit operation for different loading regulation options in daily and weekly diagrams. We proved the change in the prime cost of electric power depending on the operation regimes and annual daily number of unloading (non-use) of the power unit's installed capacity. According to the calculation results, the prime cost of electric power for the assumed initial data varies from 11.3 cents/(kW h) in the basic regime of power unit operation (with an equivalent operation time of 166700 hours) to 15.5 cents/(kW h) in the regime with night and holiday shutdowns. The reduction of using the installed capacity of power unit at varying regimes from 3.5 to 11.9 hours per day can increase the prime cost of energy from 4.2 to 37.4%. Furthermore, repair and maintenance costs grow by 4.5% and by 3 times, respectively, in comparison with the basic regime. These results indicate the need to create special maneuverable equipment for working in the varying section of the electric load diagram.

  9. Conductive heat flux in VC-1 and the thermal regime of Valles Caldera, Jemez Mountains, New Mexico

    NASA Astrophysics Data System (ADS)

    Sass, J. H.; Morgan, Paul

    1988-06-01

    Over 5% of heat in the western United States is lost through Quaternary silicic volcanic centers, including the Valles caldera in north central New Mexico. These centers are the sites of major hydrothermal activity and upper crustal metamorphism, metasomatism, and mineralization, producing associated geothermal resources. We present new heat flow data from Valles caldera core hole 1 (VC-1), drilled in the southwestern margin of the Valles caldera. Thermal conductivities were measured on 55 segments of core from VC-1, waxed and wrapped to preserve fluids. These values were combined with temperature gradient data to calculate heat flow. Above 335 m, which is probably unsaturated, heat flow is 247±16 mW m-2. The only deep temperature information available is from an uncalibrated commercial log made 19 months after drilling. Gradients, derived from uncalibrated temperature logs, and conductivities are inversely correlated between 335 and 737 m, indicating a conductive thermal regime, and component heat fluxes over three depth intervals (335-539 m, 549-628 m, and 628-737 m) are in excellent agreement with each other with an average of 504±15 mW m-2. Temperature logs to 518 m depth with well-calibrated temperature sensors result in a revised heat flow of 463±15 mW m. We use shallow thermal gradient data from 75 other sites in and around the caldera to interpret the thermal regime at the VC-1 site. A critical review of published thermal conductivity data from the Valles caldera yields an average thermal conductivity of ≥1 W m-1 K-1 for the near-surface tuffaceous material, and we assume that shallow gradient values (°C km-1) are approximately numerically equal to heat flow (mW m-2). Heat loss from the caldera is asymmetrically distributed, with higher values (400 mW m-2 or higher) concentrated in the west-southwestern quadrant of the caldera. This quadrant also contains the main drainage from the caldera and the youngest volcanism associated with the caldera. We

  10. Ground-Based Experiments on Vibrational Thermal Convection

    NASA Technical Reports Server (NTRS)

    Schatz, Michael F.; Rogers, Jeffrey L.

    1999-01-01

    Ground-based experiments on g-jitter effects in fluid flow provide insight that complements both theoretical studies and space-based experiments on this problem. We report preliminary results for experiments on Rayleigh-Benard convection subjected to time-dependent accelerations on a shaker table. For sinusoidal modulation, two qualitatively different pattern forming mechanisms come into play: geometry induced wavenumber selection (as in the standard "no-shake" Rayleigh-Benard problem) and dispersion induced wavenumber selection due to parametric instability (as in the Faraday surface-wave problem). We discuss preliminary results on the competition and co-existence of patterns due to these different instability mechanisms. We also discuss the implications of this work on the general question of pattern formation in the presence of noise.

  11. I-scan thermal lens experiment in the pulse regime for measuring two-photon absorption coefficient

    NASA Astrophysics Data System (ADS)

    Rodríguez, L.; Echevarria, L.; Fernandez, A.

    2007-09-01

    We present a new pump-probe mode-mismatched thermal lens method for pulse excitation aimed to the measurement of nonlinear absorption coefficient in optical materials. We develop a theoretical model based on the Fresnel diffraction approximation and their predictions are verified experimentally with samples of Rhodamine 6G and Rhodamine B in ethanol solution. The principal advantage of this technique is that it does not require any mechanical movement during measurement. Below we perform the new type of thermal lens experiment in the pulse regime for the measurement of nonlinear absorption coefficient in transparent samples and we demonstrate the validity of theoretical predictions using an alternative method to the classical thermal lens technique.

  12. Adapting of the Background-Oriented Schlieren (BOS) Technique in the Characterization of the Flow Regimes in Thermal Spraying Processes

    NASA Astrophysics Data System (ADS)

    Tillmann, W.; Abdulgader, M.; Rademacher, H. G.; Anjami, N.; Hagen, L.

    2014-01-01

    In thermal spraying technique, the changes in the in-flight particle velocities are considered to be only a function of the drag forces caused by the dominating flow regimes in the spray jet. Therefore, the correct understanding of the aerodynamic phenomena occurred at nozzle out let and at the substrate interface is an important task in the targeted improvement in the nozzle and air-cap design as well as in the spraying process in total. The presented work deals with the adapting of an innovative technique for the flow characterization called background-oriented Schlieren. The flow regimes in twin wire arc spraying (TWAS) and high velocity oxygen fuel (HVOF) were analyzed with this technique. The interfering of the atomization gas flow with the intersected wires causes in case of TWAS process a deformation of the jet shape. It leads also to areas with different aero dynamic forces. The configurations of the outlet air-caps in TWAS effect predominantly the outlet flow characteristics. The ratio between fuel and oxygen determine the dominating flow regimes in the HVOF spraying jet. Enhanced understanding of the aerodynamics at outlet and at the substrate interface could lead to a targeted improvement in thermal spraying processes.

  13. Measuring glacier surface temperatures with ground-based thermal infrared imaging

    NASA Astrophysics Data System (ADS)

    Aubry-Wake, Caroline; Baraer, Michel; McKenzie, Jeffrey M.; Mark, Bryan G.; Wigmore, Oliver; Hellström, Robert È.; Lautz, Laura; Somers, Lauren

    2015-10-01

    Spatially distributed surface temperature is an important, yet difficult to observe, variable for physical glacier melt models. We utilize ground-based thermal infrared imagery to obtain spatially distributed surface temperature data for alpine glaciers. The infrared images are used to investigate thermal microscale processes at the glacier surface, such as the effect of surface cover type and the temperature gradient at the glacier margins on the glacier's temperature dynamics. Infrared images were collected at Cuchillacocha Glacier, Cordillera Blanca, Peru, on 23-25 June 2014. The infrared images were corrected based on ground truth points and local meteorological data. For the control points, the Pearson's correlation coefficient between infrared and station temperatures was 0.95. The ground-based infrared camera has the potential for greatly improving glacier energy budget studies, and our research shows that it is critical to properly correct the thermal images to produce robust, quantifiable data.

  14. Estimating thermal regimes of bull trout and assessing the potential effects of climate warming on critical habitats

    USGS Publications Warehouse

    Jones, Leslie A.; Muhlfeld, Clint C.; Marshall, Lucy A.; McGlynn, Brian L.; Kershner, Jeffrey L.

    2013-01-01

    Understanding the vulnerability of aquatic species and habitats under climate change is critical for conservation and management of freshwater systems. Climate warming is predicted to increase water temperatures in freshwater ecosystems worldwide, yet few studies have developed spatially explicit modelling tools for understanding the potential impacts. We parameterized a nonspatial model, a spatial flow-routed model, and a spatial hierarchical model to predict August stream temperatures (22-m resolution) throughout the Flathead River Basin, USA and Canada. Model comparisons showed that the spatial models performed significantly better than the nonspatial model, explaining the spatial autocorrelation found between sites. The spatial hierarchical model explained 82% of the variation in summer mean (August) stream temperatures and was used to estimate thermal regimes for threatened bull trout (Salvelinus confluentus) habitats, one of the most thermally sensitive coldwater species in western North America. The model estimated summer thermal regimes of spawning and rearing habitats at <13 C° and foraging, migrating, and overwintering habitats at <14 C°. To illustrate the useful application of such a model, we simulated climate warming scenarios to quantify potential loss of critical habitats under forecasted climatic conditions. As air and water temperatures continue to increase, our model simulations show that lower portions of the Flathead River Basin drainage (foraging, migrating, and overwintering habitat) may become thermally unsuitable and headwater streams (spawning and rearing) may become isolated because of increasing thermal fragmentation during summer. Model results can be used to focus conservation and management efforts on populations of concern, by identifying critical habitats and assessing thermal changes at a local scale.

  15. Morphology control on hyporheic zone hydrodynamics: implication on redox and thermal regimes (Invited)

    NASA Astrophysics Data System (ADS)

    Marzadri, A.; Tonina, D.; Bellin, A.

    2013-12-01

    . Through this parameter we are able to define two dimensionless Damköhler numbers DaO, and DaT, which relate river morphology, through τ50, with the redox and the thermal regime within the hyporheic zone, respectively. In particular, DaO quantifies the biogeochemical status of the hyporheic zone through the ratio between τ50 and the time needed to consume dissolved oxygen to a prescribed threshold concentration (τlim), below which reductive reactions are activated: (DaO = τ50/τlim). In addition, DaT quantifies the importance of the temperature daily oscillations of the stream water on hyporheic environment through the ratio between τ50, and the time limit for which the amplitude of daily temperature oscillations of hyporheic waters are 1/e of those at the stream water. Our analysis showed that contrary to popular models such as transient storage, our approach is able to capture the relationship between moments recently proposed by González-Pinzón et al., (2013) in a study analyzing a large dataset of experimental BTCs. Moreover, through the Damköhler numbers we are able to define a new theoretical framework for scaling results at both the morphological-unit and stream-reach scales. González-Pinzón, R., R. Haggerty, and M. Dentz (2013), Scaling and predicting solute transport processes in streams, Water Resour. Res., 49, doi:10.1002/wrcr.20280.

  16. Lattice thermal conductivity of crystalline and amorphous silicon with and without isotopic effects from the ballistic to diffusive thermal transport regime

    SciTech Connect

    Park, Minkyu; Lee, In-Ho; Kim, Yong-Sung

    2014-07-28

    Thermal conductivity of a material is an important physical parameter in electronic and thermal devices, and as the device size shrinks down, its length-dependence becomes unable to be neglected. Even in micrometer scale devices, materials having a long mean free path of phonons, such as crystalline silicon (Si), exhibit a strong length dependence of the thermal conductivities that spans from the ballistic to diffusive thermal transport regime. In this work, through non-equilibrium molecular-dynamics (NEMD) simulations up to 17 μm in length, the lattice thermal conductivities are explicitly calculated for crystalline Si and up to 2 μm for amorphous Si. The Boltzmann transport equation (BTE) is solved within a frequency-dependent relaxation time approximation, and the calculated lattice thermal conductivities in the BTE are found to be in good agreement with the values obtained in the NEMD. The isotopic effects on the length-dependent lattice thermal conductivities are also investigated both in the crystalline and amorphous Si.

  17. Quantifying stream thermal regimes at multiple scales: Combining thermal infrared imagery and stationary stream temperature data in a novel modeling framework

    NASA Astrophysics Data System (ADS)

    Vatland, Shane J.; Gresswell, Robert E.; Poole, Geoffrey C.

    2015-01-01

    Accurately quantifying stream thermal regimes can be challenging because stream temperatures are often spatially and temporally heterogeneous. In this study, we present a novel modeling framework that combines stream temperature data sets that are continuous in either space or time. Specifically, we merged the fine spatial resolution of thermal infrared (TIR) imagery with hourly data from 10 stationary temperature loggers in a 100 km portion of the Big Hole River, MT, USA. This combination allowed us to estimate summer thermal conditions at a relatively fine spatial resolution (every ˜100 m of stream length) over a large extent of stream (˜100 km of stream) during the warmest part of the summer. Rigorous evaluation, including internal validation, external validation with spatially continuous instream temperature measurements collected from a Langrangian frame of reference, and sensitivity analyses, suggests the model was capable of accurately estimating longitudinal patterns in summer stream temperatures for this system (validation RMSEs < 1°C). Results revealed considerable spatial and temporal heterogeneity in summer stream temperatures and highlighted the value of assessing thermal regimes at relatively fine spatial and temporal scales. Preserving spatial and temporal variability and structure in abiotic stream data provides a critical foundation for understanding the dynamic, multiscale habitat needs of mobile stream organisms. Similarly, enhanced understanding of spatial and temporal variation in dynamic water quality attributes, including temporal sequence and spatial arrangement, can guide strategic placement of monitoring equipment that will subsequently capture variation in environmental conditions directly pertinent to research and management objectives.

  18. Quantifying stream thermal regimes at management-pertinent scales: combining thermal infrared and stationary stream temperature data in a novel modeling framework.

    USGS Publications Warehouse

    Vatland, Shane J.; Gresswell, Robert E.; Poole, Geoffrey C.

    2015-01-01

    Accurately quantifying stream thermal regimes can be challenging because stream temperatures are often spatially and temporally heterogeneous. In this study, we present a novel modeling framework that combines stream temperature data sets that are continuous in either space or time. Specifically, we merged the fine spatial resolution of thermal infrared (TIR) imagery with hourly data from 10 stationary temperature loggers in a 100 km portion of the Big Hole River, MT, USA. This combination allowed us to estimate summer thermal conditions at a relatively fine spatial resolution (every 100 m of stream length) over a large extent of stream (100 km of stream) during during the warmest part of the summer. Rigorous evaluation, including internal validation, external validation with spatially continuous instream temperature measurements collected from a Langrangian frame of reference, and sensitivity analyses, suggests the model was capable of accurately estimating longitudinal patterns in summer stream temperatures for this system Results revealed considerable spatial and temporal heterogeneity in summer stream temperatures and highlighted the value of assessing thermal regimes at relatively fine spatial and temporal scales. Preserving spatial and temporal variability and structure in abiotic stream data provides a critical foundation for understanding the dynamic, multiscale habitat needs of mobile stream organisms. Similarly, enhanced understanding of spatial and temporal variation in dynamic water quality attributes, including temporal sequence and spatial arrangement, can guide strategic placement of monitoring equipment that will subsequently capture variation in environmental conditions directly pertinent to research and management objectives.

  19. An assessment of testing requirement impacts on nuclear thermal propulsion ground test facility design

    SciTech Connect

    Shipers, L.R.; Ottinger, C.A.; Sanchez, L.C.

    1993-10-25

    Programs to develop solid core nuclear thermal propulsion (NTP) systems have been under way at the Department of Defense (DoD), the National Aeronautics and Space Administration (NASA), and the Department of Energy (DOE). These programs have recognized the need for a new ground test facility to support development of NTP systems. However, the different military and civilian applications have led to different ground test facility requirements. The Department of Energy (DOE) in its role as landlord and operator of the proposed research reactor test facilities has initiated an effort to explore opportunities for a common ground test facility to meet both DoD and NASA needs. The baseline design and operating limits of the proposed DoD NTP ground test facility are described. The NASA ground test facility requirements are reviewed and their potential impact on the DoD facility baseline is discussed.

  20. Thermal regime and potential bedrock weathering in alpine rockwalls of Austria: Results from eight years of monitoring (2006-2014)

    NASA Astrophysics Data System (ADS)

    Kellerer-Pirklbauer, Andreas; Wecht, Matthias

    2015-04-01

    Bedrock temperature at sites with a minor winter snow cover gives a good indication for the effects of air temperature anomalies on ground thermal conditions as well as for the intensity of near-surface physical weathering in bedrock. In this study we present results from an ongoing bedrock temperature monitoring program initiated in 2006. Within the framework of this program nine surface boreholes in rockwalls with different slope orientations and two additional boreholes at flat bedrock sites were drilled between August and September 2006 and subsequently instrumented. The altogether eleven rock temperature sites (RTS) are located in the alpine periglacial zone of the Austrian Alps at latitude 46°55' to 47°22' and longitude 12°44' to 14°41'. All RTS have been installed in metamorphic rock (5 x mica schist; 6 x gneiss) at elevations between 1960 and 2725 m asl (mean 2491 m asl.). Three temperature sensors (PT1000) have been inserted at each borehole site at vertical depths of 3, 10 and 30-40 cm. At each RTS the three sensors are connected to a 3-channel miniature temperature datalogger (MTD) manufactured by GeoPrecision, Germany. Our analysis focussed on (a) the variation of mean and extreme daily temperatures at the rock surface and at depth, (b) the variation of the daily temperature range, (c) the number of freeze-thaw-cycles (FTC) and (d) effective freeze-thaw cycles for frost shattering (eFTC), (e) the duration and intensity of freeze-thaw-cycles (DI-FTC), (f) the number of hours and days within the so-called frost-cracking-window (FCW), and effects of (g) aspect and (h) snow cover on the thermal regimes in the bedrock. Results show for instance that the number of FTC and eFTC varied substantially during the observation period at all eleven RTS and at all sensor depths. However, this variation differs from site to site related to snow cover condition, elevation and aspect. For instance, at one lower-elevated (2255 m asl) north exposed RTS the number of

  1. Mountain frozen grounds as small amplitude thermal proxy in southern continental Patagonia

    NASA Astrophysics Data System (ADS)

    Ruiz, Sebastian; Beriain, Eneko; Izagirre, Eñaut; Bockheim, James; Pedro, Cid-Agüero

    2015-04-01

    Frozen grounds are an important element of the cryosphere, covering between a 20-25% of the global area. Frozen grounds are becoming a relevant object of research in the southern hemisphere, being most studies focused mainly on Antarctica. With the exception of seasonally frozen grounds, perennially frozen ground is found in continental South America, for example, in high altitude terrains from 4.600m a.s.l. in central Chile. However, scarce or not information regarding permafrost on Southern Patagonia has been reported. One of the aims of this study was to establish mountain permafrost existence at 1.200m in the southern limit of the Southern Patagonian Ice-Field, a geographically active area surrounded by different kinds of glaciers on fast retreat. The area of study presents several features of past cryogenic activity such as undefined polygonal grounds with a thick clast border and sandy-loam interior. A scarce vegetal cover is limited to lichen and moss communities. The analyzed soil does not represent a thermal barrier that may avoid heat wave dynamic along the ground profile. There was neither significant snow-cover during winter nor a vegetation layer enough to consider as insulation for the analyzed ground. Oscillations above 0°C were evidenced down to 1.8m depth during winter of 2014, ruling out the existence of permafrost at that lower limit. Year round thermal dynamic down to 1.8m in the ground profile is presented as one result of the monitoring. Small amplitude temperature fluctuations were registered upon monitoring. These minimal amplitudes were stable throughout several months and as such serve as an interesting proxy for recent and long-term climatic thermal fluctuation. The influence of winds coming from nearby glaciers highly affects near-surface amplitude. This interaction was studied. The present work is part of an ongoing monitoring network along South America that intends to fill the gap between tropical Andes and the Antarctic Peninsula.

  2. Operational Constraints on Hydropeaking and its Effects on the Hydrologic and Thermal Regime of a River in Central Chile

    NASA Astrophysics Data System (ADS)

    Olivares, M. A.; Guzman, C.; Rossel, V.; De La Fuente, A.

    2013-12-01

    Hydropower accounts for about 44% of installed capacity in Chile's Central Interconnected System, which serves most of the Chilean population. Hydropower reservoir projects can affect ecosystems by changing the hydrologic regime and water quality. Given its volumen regulation capacity, low operation costs and fast response to demand fluctuations, reservoir hydropower plants commonly operate on a load-following or hydropeaking scheme. This short-term operational pattern produces alterations in the hydrologic regime downstream the reservoir. In the case of thermally stratified reservoirs, peaking operations can affect the thermal structure of the reservoir, as well as the thermal regime downstream. In this study, we assessed the subdaily hydrologic and thermal alteration donwstream of Rapel reservoir in Central Chile for alternative operational scenarios, including a base case and several scenarios involving minimum instream flow (Qmin) and maximum hourly ramping rates (ΔQmax). Scenarios were simulated for the stratification season of summer 2009-2012 in a grid-wide short-term economic dispatch model which prescribes hourly power production by every power plant on a weekly horizon. Power time series are then translated into time series of turbined flows at each hydropower plants. Indicators of subdaily hydrologic alteration (SDHA) were computed for every scenario. Additionally, turbined flows were used as input data for a three-dimensional hydrodynamic model (CWR-ELCOM) of the reservoir which simulated the vertical temperature profile in the reservoir and the outflow temperature. For the time series of outflow temperatures we computed several indicators of subdaily thermal alteration (SDTA). Operational constraints reduce the values of both SDHA and SDTA indicators with respect to the base case. When constraints are applied separately, the indicators of SDHA decrease as each type of constraint (Qmin or ΔQmax) becomes more stringent. However, ramping rate

  3. Thermal ground-state ordering and elementary excitations in artificial magnetic square ice

    NASA Astrophysics Data System (ADS)

    Morgan, Jason P.; Stein, Aaron; Langridge, Sean; Marrows, Christopher H.

    2011-01-01

    Recent advances in nanotechnology allow model systems to be constructed, in which frustrated interactions can be tuned at will, such as artificial spin ice. The symmetry of the square ice lattice leads to the emergence of a long-range-ordered ground state from the manifold of frustrated states. However, it is experimentally very difficult to access using the effective thermodynamics of rotating-field demagnetization protocols, because the energy barriers to thermal equilibrium are extremely large. Here we study an as-fabricated sample that approaches the ground state very closely. We identify the small localized departures from the ground state as elementary excitations of the system, at frequencies that follow a Boltzmann law. We therefore identify the state we observe as the frozen-in residue of true thermodynamics that occurred during the fabrication of the sample. The relative proportions of different excitations are suggestive of monopole interactions during thermalization.

  4. Thermal radiation effects on magnetohydrodynamic free convection heat and mass transfer from a sphere in a variable porosity regime

    NASA Astrophysics Data System (ADS)

    Prasad, V. Ramachandra; Vasu, B.; Bég, O. Anwar; Parshad, Rana D.

    2012-02-01

    A mathematical model is presented for multiphysical transport of an optically-dense, electrically-conducting fluid along a permeable isothermal sphere embedded in a variable-porosity medium. A constant, static, magnetic field is applied transverse to the cylinder surface. The non-Darcy effects are simulated via second order Forchheimer drag force term in the momentum boundary layer equation. The surface of the sphere is maintained at a constant temperature and concentration and is permeable, i.e. transpiration into and from the boundary layer regime is possible. The boundary layer conservation equations, which are parabolic in nature, are normalized into non-similar form and then solved numerically with the well-tested, efficient, implicit, stable Keller-box finite difference scheme. Increasing porosity ( ɛ) is found to elevate velocities, i.e. accelerate the flow but decrease temperatures, i.e. cool the boundary layer regime. Increasing Forchheimer inertial drag parameter ( Λ) retards the flow considerably but enhances temperatures. Increasing Darcy number accelerates the flow due to a corresponding rise in permeability of the regime and concomitant decrease in Darcian impedance. Thermal radiation is seen to reduce both velocity and temperature in the boundary layer. Local Nusselt number is also found to be enhanced with increasing both porosity and radiation parameters.

  5. Progeny of Osmia lignaria from distinct regions differ in developmental phenology and survival under a common thermal regime.

    PubMed

    Pitts-Singer, Theresa L; Cane, James H; Trostle, Glen

    2014-08-01

    Many insects, including some bees, have extensive subcontinental distributions that can differ in climatic conditions. Within and beyond these distributions, humans intentionally transport beneficial insects, including bees, to non-natal geographic locations. Insects also are experiencing unprecedented climatic change in their resident localities. For solitary bees, we know very little about the adaptive plasticity and geographic variation in developmental physiology that accommodates the different climates experienced within distributional ranges. Osmia lignaria Say (Hymenoptera: Megachilidae) is a widely distributed North American spring-emerging bee being developed as a managed pollinator for tree fruit crops, including almonds. We examined the development and survival of O. lignaria progeny that were descended from populations sourced from southern California, western Washington, and northern Utah, and then were reared together under an hourly and weekly temperature regime simulating those of a California almond-growing region. We found that developmental physiologies of Washington and Utah progeny were generally similar. However, California progeny developed slower, were more metabolically active, and survived better under California conditions than did populations native to regions at higher latitudes. Regardless of geographic origin, cocooned adults managed under prescribed thermal regimes emerged faster and lived longer after wintering. Progeny of parents from different regions exhibited some acclimatory plasticity in developmental phenologies to a novel climatic regime, but overall their responses reflected their geographic origins. This outcome is consistent with their developmental phenologies being largely heritable adaptations to regional climates. PMID:24879969

  6. Thermal and Fluid Modeling of the CRYogenic Orbital TEstbed (CRYOTE) Ground Test Article (GTA)

    NASA Technical Reports Server (NTRS)

    Piryk, David; Schallhorn, Paul; Walls, Laurie; Stopnitzky, Benny; Rhys, Noah; Wollen, Mark

    2012-01-01

    The purpose of this study was to anchor thermal and fluid system models to data acquired from a ground test article (GTA) for the CRYogenic Orbital TEstbed - CRYOTE. To accomplish this analysis, it was broken into four primary tasks. These included model development, pre-test predictions, testing support at Marshall Space Flight Center (MSFC} and post-test correlations. Information from MSFC facilitated the task of refining and correlating the initial models. The primary goal of the modeling/testing/correlating efforts was to characterize heat loads throughout the ground test article. Significant factors impacting the heat loads included radiative environments, multi-layer insulation (MLI) performance, tank fill levels, tank pressures, and even contact conductance coefficients. This paper demonstrates how analytical thermal/fluid networks were established, and it includes supporting rationale for specific thermal responses seen during testing.

  7. Contrasted thermal regimes do not influence digestion and growth rates in a snake from a temperate climate.

    PubMed

    Michel, Catherine Louise; Bonnet, Xavier

    2010-01-01

    Temperature influences almost all life-history traits. For a period of 3 mo, we placed four groups of snakes under four contrasted thermal treatments: (1) a natural regime (NR), based on daily variations (24-h cycle); (2) an accelerated regime (AR), where the thermoperiod fluctuated rapidly (12-h cycle); (3) a slow regime (SR; 48-h cycle); and (4) a cool stable regime (ZR; no fluctuation). The mean temperature, set at 23°C, was identical for the four groups. For the first three groups (NR, AR, SR), ambient temperature fluctuated between 18°C and 28°C. Relative humidity and photoperiod were constant. We recorded feeding success, digestion efficiency, growth rate, activity, and ecdysis events. Differences between groups were expected because of varied exposure to the optimal temperatures, most notably in the ZR group, where the preferred body temperature for digestion (approximately 30°C) would not be reached. Surprisingly, there was no significant effect of the experimental treatment on feeding rate, digestion, body mass increase, and growth rate. Our results do not conform to the paradigm stipulating that maximal body temperature selected by ectotherms necessarily corresponds to the most efficient for resource assimilation and that temperature fluctuations are essential. We propose that increasing the digestive tract's performance through body-temperature elevation trades off against elevated (parasite) energy expenditure from the rest of the body. The main advantage of high body temperatures would be to reduce the amount of time necessary to assimilate prey rather than to improve the net mass gain during digestion. PMID:20969448

  8. Flow regimes in a vertical Taylor-Couette system with a radial thermal gradient

    NASA Astrophysics Data System (ADS)

    Guillerm, R.; Kang, C.; Savaro, C.; Lepiller, V.; Prigent, A.; Yang, K.-S.; Mutabazi, I.

    2015-09-01

    A rich variety of flow regimes in a Newtonian fluid inside a vertical large-aspect ratio and a wide-gap Taylor-Couette system with a radial temperature gradient has been determined in experiments and in direct numerical simulations (DNSs). Compared to previous experiments and numerical studies, a wider range of temperature differences (i.e., of the Grashof number Gr) and of the rotation rate (the Taylor number Ta) has been covered. The combined effect of rotation and of the radial temperature gradient is the occurrence of helicoidal vortices or modulated waves at the onset. Stationary axisymmetric vortices are found for very weak temperature differences. A good agreement was found for critical states between results from experiments, linear stability analysis, and DNS. Higher instability modes have been determined for a wide range of parameters and a state diagram of observable flow regimes has been established in the plane spanned by Gr and Ta. Some higher states observed in experiments were retrieved in DNS.

  9. PATRAN and P/THERMAL applications for thermal modeling. [SP-100 Ground Engineering Station

    SciTech Connect

    Valdiviez, R.; Crea, B.A.

    1991-07-01

    The standard that has been established over the last decade or so in performing numerical modeling for analysis purposes is to make creation of the computational grid and results presentation less time and effort consuming than the analysis function itself. Software packages known as pre- and post-processors have been developed and made available in various forms and sizes for the engineering analyst's use. These packages reduce the effort and time required of the analyst to perform pre- and post-operations on a given model. PATRAN is one such pre- and post-processing software package. PATRAN provides a large array of capabilities to enable geometric representation and creation of the analysis model. This software package also incorporates interfacing routines which enable a model created in PATRAN to be translated into the input format of many other analysis codes. This paper discusses the use of PATRAN as a pre- and post-processor and the software package P/THERMAL as the analysis code for the steady state and transient thermal analysis of a vacuum vessel. The design objective of the vessel is to duplicate the conditions of outer space and provide containment for a test nuclear reactor designed for space application. This objective creates a challenging thermal analysis effort. The use of P/THERMAL in meeting this challenge is also discussed. P/THERMAL's ability to facilitate and perform thermal analysis is recognized in this analysis task. 2 figs.

  10. Detailed predictions of climate induced changes in the thermal and flow regimes in mountain streams of the Iberian Peninsula

    NASA Astrophysics Data System (ADS)

    Santiago, José M.; Muñoz-Mas, Rafael; García de Jalón, Diego; Solana, Joaquín; Alonso, Carlos; Martínez-Capel, Francisco; Ribalaygua, Jaime; Pórtoles, Javier; Monjo, Robert

    2016-04-01

    Streamflow and temperature regimes are well-known to influence on the availability of suitable physical habitat for instream biological communities. General Circulation Models (GCMs) have predicted significant changes in timing and geographic distribution of precipitation and atmospheric temperature for the ongoing century. However, differences in these predictions may arise when focusing on different spatial and temporal scales. Therefore, to perform substantiated mitigation and management actions detailed scales are necessary to adequately forecast the consequent thermal and flow regimes. Regional predictions are relatively abundant but detailed ones, both spatially and temporally, are still scarce. The present study aimed at predicting the effects of climate change on the thermal and flow regime in the Iberian Peninsula, refining the resolution of previous studies. For this purpose, the study encompassed 28 sites at eight different mountain rivers and streams in the central part of the Iberian Peninsula (Spain). The daily flow was modelled using different daily, monthly and quarterly lags of the historical precipitation and temperature time series. These precipitation-runoff models were developed by means of M5 model trees. On the other hand water temperature was modelled at similar time scale by means of nonlinear regression from dedicated site-specific data. The developed models were used to simulate the temperature and flow regime under two Representative Concentration Pathway (RCPs) climate change scenarios (RCP 4.5 and RCP 8.5) until the end of the present century by considering nine different GCMs, which were pertinently downscaled. The precipitation-runoff models achieved high accuracy (NSE>0.7), especially in regards of the low flows of the historical series. Results concomitantly forecasted flow reductions between 7 and 17 % (RCP4.5) and between 8 and 49% (RCP8.5) of the annual average in the most cases, being variable the magnitude and timing at each

  11. Big dams and salmon evolution: changes in thermal regimes and their potential evolutionary consequences.

    PubMed

    Angilletta, Michael J; Ashley Steel, E; Bartz, Krista K; Kingsolver, Joel G; Scheuerell, Mark D; Beckman, Brian R; Crozier, Lisa G

    2008-05-01

    Dams designed for hydropower and other purposes alter the environments of many economically important fishes, including Chinook salmon (Oncorhynchus tshawytscha). We estimated that dams on the Rogue River, the Willamette River, the Cowlitz River, and Fall Creek decreased water temperatures during summer and increased water temperatures during fall and winter. These thermal changes undoubtedly impact the behavior, physiology, and life histories of Chinook salmon. For example, relatively high temperatures during the fall and winter should speed growth and development, leading to early emergence of fry. Evolutionary theory provides tools to predict selective pressures and genetic responses caused by this environmental warming. Here, we illustrate this point by conducting a sensitivity analysis of the fitness consequences of thermal changes caused by dams, mediated by the thermal sensitivity of embryonic development. Based on our model, we predict Chinook salmon likely suffered a decrease in mean fitness after the construction of a dam in the Rogue River. Nevertheless, these demographic impacts might have resulted in strong selection for compensatory strategies, such as delayed spawning by adults or slowed development by embryos. Because the thermal effects of dams vary throughout the year, we predict dams impacted late spawners more than early spawners. Similar analyses could shed light on the evolutionary consequences of other environmental perturbations and their interactions. PMID:25567632

  12. Comparison of thermal modeling and experimental results of a generic model for ground vehicle

    NASA Astrophysics Data System (ADS)

    Bushlin, Y.; Lessin, A.; Reinov, A.

    2006-05-01

    Accurate thermal modeling requires verification and validation of the model and software being used. For basic evaluation of thermal prediction models and software tools, a generic model - CUBI was build. The model was designed to have simple geometry yet, consisted of similar characteristics as of a ground vehicle. The model was equipped with thermocouples for measuring its temperature variations and was placed in a typical desert environment for field testing. The experimental setup also included a meteorological station. The data collected was used for the thermal behavior analysis of the generic model and for comparison with the thermal calculations predictions. Comparison of the results shows sufficient compliance but yet reviles some issues in the modeling that should be addressed.

  13. High power tungstate-crystal Raman laser operating in the strong thermal lensing regime.

    PubMed

    McKay, Aaron; Kitzler, Ondrej; Mildren, Richard P

    2014-01-13

    We report an investigation into a double metal tungstate Raman laser when pumped at elevated average powers. Potassium gadolinium tungstate (KGW) was placed in an external cavity configured for second-Stokes output and pumped at pulse repetition rate of 38 kHz with up to 46 W of average power. For output powers above 3 W, we observe preferential excitation of Hermite-Gaussian transverse modes whose order in the X(1)(') principal direction of the thermal expansion tensor scales linearly with Raman power. We deduce that strong astigmatic thermal lensing is induced in the Raman crystal with a negative component in the X(1)(') direction. At maximum pump power, 8.3 W of output power was obtained at a conversion efficiency of 18%. PMID:24515030

  14. Modeling thermal structure, ice cover regime and sensitivity to climate change of two regulated lakes - a Norwegian case study

    NASA Astrophysics Data System (ADS)

    Gebre, Solomon; Boissy, Thibault; Alfredsen, Knut

    2013-04-01

    A great number of river and lakes in Norway and the Nordic region at large are regulated for water management such as hydropower production. Such regulations have the potential to alter the thermal and hydrological regimes in the lakes and rivers downstream impacting on river environment and ecology. Anticipated changes as a result of climate change in meteorological forcing data such as air temperature and precipitation cause changes in the water balance, water temperature and ice cover duration in the reservoirs. This may necessitate changes in operational rules as part of an adaptation strategy for the future. In this study, a one dimensional (1D) lake thermodynamic and ice cover model (MyLake) has been modified to take into account the effect of dynamic outflows in reservoirs and applied to two small but relatively deep regulated lakes (reservoirs) in Norway (Follsjøen and Tesse). The objective was to assess climate change impacts on the seasonal thermal characteristics, the withdrawal temperatures, and the reservoir ice cover dynamics with current operational regimes. The model solves the vertical energy balance on a daily time-step driven by meteorological and hydrological forcings: 2m air temperature, precipitation, 2m relative humidity, 10m wind speed, cloud cover, air pressure, solar insolation, inflow volume, inflow temperature and reservoir outflows. Model calibration with multi-seasonal data of temperature profiles showed that the model performed well in simulating the vertical water temperature profiles for the two study reservoirs. The withdrawal temperatures were also simulated reasonably well. The comparison between observed and simulated lake ice phenology (which were available only for one of the reservoirs - Tesse) was also reasonable taking into account the uncertainty in the observational data. After model testing and calibration, the model was then used to simulate expected changes in the future (2080s) due to climate change by considering

  15. Conductive heat flux in VC-1 and the thermal regime of Valles caldera, Jemez Mountains, New Mexico ( USA).

    USGS Publications Warehouse

    Sass, J.H.; Morgan, P.

    1988-01-01

    Over 5% of heat in the western USA is lost through Quaternary silicic volcanic centers, including the Valles caldera in N central New Mexico. These centers are the sites of major hydrothermal activity and upper crustal metamorphism, metasomatism, and mineralization, producing associated geothermal resources. Presents new heat flow data from Valles caldera core hole 1 (VC-1), drilled in the SW margin of the Valles caldera. Thermal conductivities were measured on 55 segments of core from VC-1, waxed and wrapped to preserve fluids. These values were combined with temperature gradient data to calculate heat flow. Above 335 m, which is probably unsaturated, heat flow is 247 + or - 16 mW m-2. Inteprets the shallow thermal gradient data and the thermal regime at VC-1 to indicate a long-lived hydrothermal (and magmatic) system in the southwestern Valles caldera that has been maintained through the generation of shallow magma bodies during the long postcollapse history of the caldera. High heat flow at the VC-1 site is interpreted to result from hot water circulating below the base of the core hole, and we attribute the lower heat flow in the unsaturated zone is attributed to hydrologic recharge. -from Authors

  16. Effluent Containment System for space thermal nuclear propulsion ground test facilities

    SciTech Connect

    1995-08-01

    This report presents the research and development study work performed for the Space Reactor Power System Division of the U.S. Department of Energy on an innovative ECS that would be used during ground testing of a space nuclear thermal rocket engine. A significant portion of the ground test facilities for a space nuclear thermal propulsion engine are the effluent treatment and containment systems. The proposed ECS configuration developed recycles all engine coolant media and does not impact the environment by venting radioactive material. All coolant media, hydrogen and water, are collected, treated for removal of radioactive particulates, and recycled for use in subsequent tests until the end of the facility life. Radioactive materials removed by the treatment systems are recovered, stored for decay of short-lived isotopes, or packaged for disposal as waste. At the end of the useful life, the facility will be decontaminated and dismantled for disposal.

  17. TRS: a tool for the evaluation of thermal recycling in Ground Water Heat Pumps

    NASA Astrophysics Data System (ADS)

    Casasso, Alessandro; Sethi, Rajandrea

    2015-04-01

    Ground Water Heat Pumps (GWHP) are based on the thermal exchange with groundwater, which is usually reinjected into the same aquifer. This often leads to the return of thermally altered water to the extraction well, the so-called thermal recycling, thus impairing the long-term efficiency of a GWHP. Some simplified mathematical models have been already developed to simulate this phenomenon, but they require an imposed injection temperature (constant or variable), which should be know a priori. This simplification is a bit crude for GWHP modelling, for which it is more realistic to impose a temperature difference between the extraction and the injection well. We have therefore developed the freely available software TRS (Thermal Recycling Simulator), that overcomes this limitation by taking into account the variation of the injection temperature due to the thermal short-circuit. The software is based on the finite-difference approximation of the potential flow theory and it has been validated through the comparison with flow and heat transport simulations with FEFLOW. We have also developed an explicit formula for the calculation of the thermal alteration in a well doublet aligned with the groundwater flow direction, which is the ideal well arrangement. The parameters of the formula have been calibrated by fitting the results of a large series of simulations with TRS. The mathematical tools we developed can be used for preliminary feasibility studies of GWHP, for fast sensitivity analyses and for the large-scale mapping of the thermal exchange capacity of an aquifer.

  18. Arctic Oscillation impact on thermal regime of the Baltic region Eastern part

    NASA Astrophysics Data System (ADS)

    Gecaite, Indre; Pogoreltsev, Aleksandr; Ugryumov, Aleksandr

    2016-04-01

    Statistical estimations of Arctic Oscillation (AO) impact on air temperature regime in the Eastern part of Baltic region are presented. The region is characterized by high inter-annual and inter-seasonal variabilities. It is important to note that in the region of global warming extremely low winter temperatures can be observed on the European territory of Russia. AO is one of large-scale global structures of atmospheric circulation closely associated with weather variability in Northern Europe. AO anomalies occur in the upper atmosphere (stratosphere) and only then transferred to tropospheric lower layers. The anomalies can be preserved during long period up to two months, so they can be predictors in long-range weather forecast. In turn, changes in stratospheric polar vortex and sudden stratospheric warmings can be related to the geomagnetic activity. Perhaps, the geomagnetic activity influences the meridional temperature gradient and then changes in the structure of the stratospheric zonal wind. In turn, the changes have an impact on the tropospheric circulation. The stratosphere-troposphere connection occurs during winter months. Therefore, the paper presents the analysis of extremely cold winter anomalies in the Eastern part of Baltic Sea region. At the same time, we considered atmospheric circulation peculiarities related to AO phase change. The analyzable time interval covers 1951-2014.

  19. Combination of Heat Shock and Enhanced Thermal Regime to Control the Growth of a Persistent Legionella pneumophila Strain.

    PubMed

    Bédard, Emilie; Boppe, Inès; Kouamé, Serge; Martin, Philippe; Pinsonneault, Linda; Valiquette, Louis; Racine, Jules; Prévost, Michèle

    2016-01-01

    Following nosocomial cases of Legionella pneumophila, the investigation of a hot water system revealed that 81.5% of sampled taps were positive for L. pneumophila, despite the presence of protective levels of copper in the water. A significant reduction of L. pneumophila counts was observed by culture after heat shock disinfection. The following corrective measures were implemented to control L. pneumophila: increasing the hot water temperature (55 to 60 °C), flushing taps weekly with hot water, removing excess lengths of piping and maintaining a water temperature of 55 °C throughout the system. A gradual reduction in L. pneumophila counts was observed using the culture method and qPCR in the 18 months after implementation of the corrective measures. However, low level contamination was retained in areas with hydraulic deficiencies, highlighting the importance of maintaining a good thermal regime at all points within the system to control the population of L. pneumophila. PMID:27092528

  20. Combination of Heat Shock and Enhanced Thermal Regime to Control the Growth of a Persistent Legionella pneumophila Strain

    PubMed Central

    Bédard, Emilie; Boppe, Inès; Kouamé, Serge; Martin, Philippe; Pinsonneault, Linda; Valiquette, Louis; Racine, Jules; Prévost, Michèle

    2016-01-01

    Following nosocomial cases of Legionella pneumophila, the investigation of a hot water system revealed that 81.5% of sampled taps were positive for L. pneumophila, despite the presence of protective levels of copper in the water. A significant reduction of L. pneumophila counts was observed by culture after heat shock disinfection. The following corrective measures were implemented to control L. pneumophila: increasing the hot water temperature (55 to 60 °C), flushing taps weekly with hot water, removing excess lengths of piping and maintaining a water temperature of 55 °C throughout the system. A gradual reduction in L. pneumophila counts was observed using the culture method and qPCR in the 18 months after implementation of the corrective measures. However, low level contamination was retained in areas with hydraulic deficiencies, highlighting the importance of maintaining a good thermal regime at all points within the system to control the population of L. pneumophila. PMID:27092528

  1. Evaluation of thermal regimes for transported ambassador ectotherms: One size does not fit all.

    PubMed

    Tetzlaff, Sasha J; Tetzlaff, Kristin E; Connors, Richard J

    2016-07-01

    Providing appropriate environmental temperatures for captive ectotherms should be a husbandry priority. This can be especially challenging for ectotherms that are routinely transported, such as those used in education programs at zoos, because they are unable to thermoregulate while confined in non-temperature controlled, compact carriers. To assess if ectotherms used in the Fort Wayne Children's Zoo's outreach programs experienced appropriate transit temperatures during cold weather, we placed temperature loggers inside two sizes of transport carriers, half containing a heat source (bottle of hot water) and half not (control). While transport temperatures were appropriate for many ectotherms, this simple procedure failed to meet the thermal preferences of species with relatively low or high preferred temperatures such as the eastern tiger salamander (Ambystoma tigrinum) and the spiny-tailed lizard (Uromastyx maliensis), respectively. We found large heated carriers were warmer than small heated carriers, but the temperatures of control carriers did not differ. Despite considerable interspecific variation, large heated carriers provided higher thermal quality environments than both small heated and control carriers for all species except eastern tiger salamanders. We suggest further thermal monitoring of ectotherms during transit with the aim of identifying appropriate heat sources and developing efficient and effective transportation protocols. This could be achieved by modifying transport carriers so that animals are able to thermoregulate. Limiting or ceasing their use when appropriate temperatures cannot be provided may be necessary. Particular attention should be given to species with temperature preferences markedly different than the majority of others in a given collection. Zoo Biol. 35:339-345, 2016. © 2016 Wiley Periodicals, Inc. PMID:27007783

  2. A modeling assessment of the thermal regime for an urban sport fishery

    NASA Astrophysics Data System (ADS)

    Bartholow, John M.

    1991-11-01

    Water temperature is almost certainly a limiting factor in the maintenance of a self-sustaining rainbow trout ( Oncorhynchus mykiss, formerly Salmo gairdneri) and brown trout ( Salmo trutta) fishery in the lower reaches of the Cache la Poudre River near Fort Collins, Colorado, USA. Irrigation diversions dewater portions of the river, but cold reservoir releases moderate water temperatures during some periods. The US Fish and Wildlife Service’s Stream Network Temperature Model (SNTEMP) was applied to a 31-km segment of the river using readily available stream geometry and hydrological and meteorological data. The calibrated model produced satisfactory water temperature predictions ( R 2=0.88, P<0.001, N=49) for a 62-day summer period. It was used to evaluate a variety of flow and nonflow alternatives to keep water temperatures below 23.3°C for the trout. Supplemental flows or reduced diversions of 3 m3/sec would be needed to maintain suitable summer temperatures throughout most of the study area. Such flows would be especially beneficial during weekends when current irrigation patterns reduce flows. The model indicated that increasing the riparian shade would result in little improvement in water temperatures but that decreasing the stream width would result in significant temperature reductions. Introduction of a more thermally tolerant redband trout ( Oncorhynchus sp.), or smallmouth bass ( Micropterus dolomieui) might prove beneficial to the fishery. Construction of deep pools for thermal refugia might also be helpful.

  3. Fast Regime Fluidized Bed Machining (FR-FBM) of Thermally Sprayed Coatings

    NASA Astrophysics Data System (ADS)

    Barletta, Massimiliano; Rubino, Gianluca; Bolelli, Giovanni; Lusvarghi, Luca

    2008-12-01

    Finishing of thermally sprayed metallic, ceramic, and cermet coatings is required to meet tolerances and requirements on surface roughness in most industrial applications. Conventional machining is a costly and time-consuming process, and is difficult to automate. Therefore, this study investigates and develops a new technique highly amenable for automation: fast regime—fluidized bed machining (FR-FBM). Atmospheric plasma sprayed TiO2, Cr2O3, and HVOF-sprayed WC-17%Co and Tribaloy-800 coatings, deposited on AISI 1040 steel substrates, were subjected to FR-FBM treatment. The effects of the leading operational parameters, namely, abrasive size, jet pressure, and processing time, were evaluated on all coatings by using a two/three-levels full factorial design of experiments. The FR-FBM treated surfaces were observed by FE-SEM and their surface finishing was evaluated by contact profilometry. Significant improvements in surface finishing of all the machined thermally sprayed coatings can always be detected, with FR-FBM being able to guarantee the precision and to ensure the closest geometrical tolerances.

  4. Exploring thermal imaging variables for the detection of stress responses in grapevine under different irrigation regimes.

    PubMed

    Grant, Olga M; Tronina, Lukasz; Jones, Hamlyn G; Chaves, M Manuela

    2007-01-01

    Temperatures of leaves or canopies can be used as indicators of stomatal closure in response to soil water deficit. In 2 years of field experiments with grapevines (Vitis vinifera L., cvs Castelão and Aragonês), it was found that thermal imaging can distinguish between irrigated and non-irrigated canopies, and even between deficit irrigation treatments. Average canopy temperature was inversely correlated with stomatal conductance measured with a porometer. Variation of the distribution of temperatures within canopies was not found to be a reliable indicator of stress. A large degree of variation between images was found in reference 'wet' and 'dry' leaves used in the first year for the calculation of an index proportional to stomatal conductance. In the second year, fully irrigated (FI) (100% Et(c)) and non-irrigated (NI) canopies were used as alternatives to wet and dry leaves. A crop water stress index utilizing these FI and NI 'references', where stressed canopies have the highest values and non-stressed canopies have the lowest values, was found to be a suitable measure for detecting stress. It is suggested that the average temperatures of areas of canopies containing several leaves may be more useful for distinguishing between irrigation treatments than the temperatures of individual leaves. Average temperatures over several leaves per canopy may be expected to reduce the impact of variation in leaf angles. The results are discussed in relation to the application of thermal imaging to irrigation scheduling and monitoring crop performance. PMID:17032729

  5. A modeling assessment of the thermal regime for an urban sport fishery

    USGS Publications Warehouse

    Bartholow, John M.

    1991-01-01

    Water temperature is almost certainly a limiting factor in the maintenance of a self-sustaining rainbow trout (Oncorhynchus mykiss, formerly Salmo gairdneri) and brown trout (Salmo trutta) fishery in the lower reaches of the Cache la Poudre River near Fort Collins, Colorado, USA. Irrigation diversions dewater portions of the river, but cold reservoir releases moderate water temperatures during some periods. The US Fish and Wildlife Service’s Stream Network Temperature Model (SNTEMP) was applied to a 31-km segment of the river using readily available stream geometry and hydrological and meteorological data. The calibrated model produced satisfactory water temperature predictions (R2=0.88,P3/sec would be needed to maintain suitable summer temperatures throughout most of the study area. Such flows would be especially beneficial during weekends when current irrigation patterns reduce flows. The model indicated that increasing the riparian shade would result in little improvement in water temperatures but that decreasing the stream width would result in significant temperature reductions. Introduction of a more thermally tolerant redband trout (Oncorhynchus sp.), or smallmouth bass (Micropterus dolomieui) might prove beneficial to the fishery. Construction of deep pools for thermal refugia might also be helpful.

  6. Thermal regime of shallow water bodies in the coastal tundra zone of the Hudson Bay Lowlands

    NASA Astrophysics Data System (ADS)

    Duguay, C. R.; Soliman, A. S.; Macrae, M. L.

    2011-12-01

    Many shallow lakes and ponds of the Arctic/sub-Arctic contain thick, organic-rich sediments, which have the potential to release significant amounts of CO2 or CH4 to the atmosphere if sediment decomposition rates increase in response to warmer temperatures caused by global warming. This may be exacerbated by a deepening of the seasonal sediment thaw depth in small water bodies that are underlain by permafrost. An important step in linking climatic conditions to rates of organic matter decomposition and gas production from shallow water bodies is an improved understanding of the thermal properties of lake sediments and how sediment temperatures fluctuate in response to changing air temperatures. This knowledge is also important if the ratio of terrestrial to aquatic landscape units in cold regions changes under a warmer climate. One approach that has been used in terrestrial permafrost environments is the examination of how mean annual permafrost surface temperature deviates from mean annual 2-m screen height air temperature (MAAT). The offset between MAAT and the mean annual sediment surface temperature (MASST) has been found to be much larger in deep aquatic systems (greater than 10 m) than in terrestrial permafrost systems due to the presence of the water column that can efficiently transfer heat through mixing. However, the efficiency of heat transfer in shallow water bodies is expected to larger in summer (thawed) than in winter (frozen) conditions, when thermal energy must move by conduction alone. The present study examined the efficiency of sediment heat transfer in shallow water bodies (less than 3 m) during summer and winter periods. Air, sediment and water temperatures of three shallow water bodies in the coastal tundra zone of the Hudson Bay Lowlands near Churchill, Manitoba, Canada were monitored (December 2009-August 2011). Arrays of thermistors and heat pulse probes were placed at 10 cm increments between 20 cm above the water/sediment interface and

  7. Redefining thermal regimes to design reserves for coral reefs in the face of climate change.

    PubMed

    Chollett, Iliana; Enríquez, Susana; Mumby, Peter J

    2014-01-01

    Reef managers cannot fight global warming through mitigation at local scale, but they can use information on thermal patterns to plan for reserve networks that maximize the probability of persistence of their reef system. Here we assess previous methods for the design of reserves for climate change and present a new approach to prioritize areas for conservation that leverages the most desirable properties of previous approaches. The new method moves the science of reserve design for climate change a step forwards by: (1) recognizing the role of seasonal acclimation in increasing the limits of environmental tolerance of corals and ameliorating the bleaching response; (2) using the best proxy for acclimatization currently available; (3) including information from several bleaching events, which frequency is likely to increase in the future; (4) assessing relevant variability at country scales, where most management plans are carried out. We demonstrate the method in Honduras, where a reassessment of the marine spatial plan is in progress. PMID:25333380

  8. Redefining Thermal Regimes to Design Reserves for Coral Reefs in the Face of Climate Change

    PubMed Central

    Chollett, Iliana; Enríquez, Susana; Mumby, Peter J.

    2014-01-01

    Reef managers cannot fight global warming through mitigation at local scale, but they can use information on thermal patterns to plan for reserve networks that maximize the probability of persistence of their reef system. Here we assess previous methods for the design of reserves for climate change and present a new approach to prioritize areas for conservation that leverages the most desirable properties of previous approaches. The new method moves the science of reserve design for climate change a step forwards by: (1) recognizing the role of seasonal acclimation in increasing the limits of environmental tolerance of corals and ameliorating the bleaching response; (2) using the best proxy for acclimatization currently available; (3) including information from several bleaching events, which frequency is likely to increase in the future; (4) assessing relevant variability at country scales, where most management plans are carried out. We demonstrate the method in Honduras, where a reassessment of the marine spatial plan is in progress. PMID:25333380

  9. Exploratory models of the earth's thermal regime during segregation of the core

    NASA Technical Reports Server (NTRS)

    Davies, G. F.

    1980-01-01

    Some simple exploratory theoretical models of the thermal effects of core segregation have been investigated, assuming an initially homogeneous earth and including convective heat transport through a 'parameterized convection' approximation. The results indicate that either (1) mantle temperatures 30% or more above present values may have resulted from the gravitational energy released during core segregation, (2) the earth retained very little of its accretional energy, (3) core segregation lasted for one billion years or more, or (4) the earth accreted heterogeneously. Option 3 seems to be precluded by terrestrial lead isotope data, and the alternatives each raise substantial questions concerning the mechanics, chemistry, and petrology of the earth's early history. There is no recognized evidence for the early hot phase of option 1, and option 4 implies, among other things, an analogous early hot phase. Although it has not been favored, option 2 may be viable.

  10. Thermal regime of the Great Basin and its implications for hydrocarbon occurrence

    SciTech Connect

    Sass, J.H.; Williams, C.F.

    1995-06-01

    The Great Basin is a province of high average heat flow (92+-9 mW m{sup -2}), but it contains sub-provinces of both higher and lower heat flow. Higher heat flow (>100 mW m{sup -2}) is characteristic of the north-central Great Basin (the Battle Mountain High, BMH) and several smaller areas along its margins. There is also a large area of lower heat flow (<60 mW m{sup -2}, the Eureka Low, EL) in the south-central portion of the province. There is hydrologic and thermal evidence that the EL is a shallow ({approximately}3 km) hydrologically controlled heat sink associated with interbasin water flow. For example, the temperature profile from a 3.7 km deep hole at Pahute Mesa in the EL indicates low heat flow in the upper 1.5 km and high heat flow in the lowermost kilometer. On the other hand, seismic and magnetic studies suggest that the heat sink in the EL extends to at least mid-crustal depths. Temperatures in the deeper parts of many basins in the BMH are higher than considered favorable for generation or stability of oil. Paradoxically, temperature-gradients as high as 100{degrees}C km{sup -1} and an underlying hydrothermal system are found within the EL in Railroad Valley, the site of the most productive oil-fields in the Great Basin. The heat source driving this hydrothermal system is a combination of local upward flow from the Paleozoic carbonate aquifer and possible thermal input from nearby igneous activity. J. B. Hulen and others have suggested that the Railroad Valley hydrothermal system has enhanced hydrocarbon transport and accelerated maturation. If a hydrothermal system is required for the formation of significant hydrocarbon reservoirs in the EL, then such reservoirs will occur only where groundwater flow in the carbonate aquifer is not removing heat from the basins.

  11. Ground Plane and Near-Surface Thermal Analysis for NASA's Constellation Program

    NASA Technical Reports Server (NTRS)

    Gasbarre, Joseph F.; Amundsen, Ruth M.; Scola, Salvatore; Leahy, Frank F.; Sharp, John R.

    2008-01-01

    Most spacecraft thermal analysis tools assume that the spacecraft is in orbit around a planet and are designed to calculate solar and planetary fluxes, as well as radiation to space. On NASA Constellation projects, thermal analysts are also building models of vehicles in their pre-launch condition on the surface of a planet. This process entails making some modifications in the building and execution of a thermal model such that the radiation from the planet, both reflected albedo and infrared, is calculated correctly. Also important in the calculation of pre-launch vehicle temperatures are the natural environments at the vehicle site, including air and ground temperatures, sky radiative background temperature, solar flux, and optical properties of the ground around the vehicle. A group of Constellation projects have collaborated on developing a cohesive, integrated set of natural environments that accurately capture worst-case thermal scenarios for the pre-launch and launch phases of these vehicles. The paper will discuss the standardization of methods for local planet modeling across Constellation projects, as well as the collection and consolidation of natural environments for launch sites. Methods for Earth as well as lunar sites will be discussed.

  12. Surface energy budget and thermal inertia at Gale Crater: Calculations from ground-based measurements

    NASA Astrophysics Data System (ADS)

    Martínez, G. M.; Rennó, N.; Fischer, E.; Borlina, C. S.; Hallet, B.; Torre Juárez, M.; Vasavada, A. R.; Ramos, M.; Hamilton, V.; Gomez-Elvira, J.; Haberle, R. M.

    2014-08-01

    The analysis of the surface energy budget (SEB) yields insights into soil-atmosphere interactions and local climates, while the analysis of the thermal inertia (I) of shallow subsurfaces provides context for evaluating geological features. Mars orbital data have been used to determine thermal inertias at horizontal scales of ~104 m2 to ~107 m2. Here we use measurements of ground temperature and atmospheric variables by Curiosity to calculate thermal inertias at Gale Crater at horizontal scales of ~102 m2. We analyze three sols representing distinct environmental conditions and soil properties, sol 82 at Rocknest (RCK), sol 112 at Point Lake (PL), and sol 139 at Yellowknife Bay (YKB). Our results indicate that the largest thermal inertia I = 452 J m-2 K-1 s-1/2 (SI units used throughout this article) is found at YKB followed by PL with I = 306 and RCK with I = 295. These values are consistent with the expected thermal inertias for the types of terrain imaged by Mastcam and with previous satellite estimations at Gale Crater. We also calculate the SEB using data from measurements by Curiosity's Rover Environmental Monitoring Station and dust opacity values derived from measurements by Mastcam. The knowledge of the SEB and thermal inertia has the potential to enhance our understanding of the climate, the geology, and the habitability of Mars.

  13. Surface energy budget and thermal inertia at Gale Crater: Calculations from ground-based measurements

    PubMed Central

    Martínez, G M; Rennó, N; Fischer, E; Borlina, C S; Hallet, B; de la Torre Juárez, M; Vasavada, A R; Ramos, M; Hamilton, V; Gomez-Elvira, J; Haberle, R M

    2014-01-01

    The analysis of the surface energy budget (SEB) yields insights into soil-atmosphere interactions and local climates, while the analysis of the thermal inertia (I) of shallow subsurfaces provides context for evaluating geological features. Mars orbital data have been used to determine thermal inertias at horizontal scales of ∼104 m2 to ∼107 m2. Here we use measurements of ground temperature and atmospheric variables by Curiosity to calculate thermal inertias at Gale Crater at horizontal scales of ∼102 m2. We analyze three sols representing distinct environmental conditions and soil properties, sol 82 at Rocknest (RCK), sol 112 at Point Lake (PL), and sol 139 at Yellowknife Bay (YKB). Our results indicate that the largest thermal inertia I = 452 J m−2 K−1 s−1/2 (SI units used throughout this article) is found at YKB followed by PL with I = 306 and RCK with I = 295. These values are consistent with the expected thermal inertias for the types of terrain imaged by Mastcam and with previous satellite estimations at Gale Crater. We also calculate the SEB using data from measurements by Curiosity's Rover Environmental Monitoring Station and dust opacity values derived from measurements by Mastcam. The knowledge of the SEB and thermal inertia has the potential to enhance our understanding of the climate, the geology, and the habitability of Mars. PMID:26213666

  14. Thermal regime and amplitude of lithosphere extension in the Sirte basin, Libya: Numerical estimates in the plane basin modeling system

    NASA Astrophysics Data System (ADS)

    Galushkin, Yu. I.; El Maghbi, Ali; El Gtlawi, M.

    2014-01-01

    The GALO basin modeling system has been applied for the numerical reconstruction of the subsidence history, variations in temperature, and maturity of the organic matter of sedimentary rocks composing the main tectonic structures of Sirte Basin. The reconstruction was carried out for eight sedimentary cross sections along the profile stretching from the Cyrenaica Platform on the eastern coast of the basin to the Hun Graben on its western wall. The interval of depths for temperature calculations included the sedimentary layer, consolidated crust, and the mantle to below 100 km. This extensive depth coverage made it possible to use the analysis of the variations in the tectonic subsidence of the basin for estimating the amplitudes and duration of the events of thermal activation and extension of the lithosphere of the basin in the history of its evolution. The modeling suggests that thermal activations of the lithosphere in the Albian-Cenomanian and Oligocene-Pleistocene are common for all tectonic structures of the Sirte Basin and the Cyrenaica Platform and that a relatively high temperature regime is also characteristic of the present-day conditions in the Sirte Basin and Cyrenaica Platform. To a considerable extent, such a regime is caused by the thermal activation of the lithosphere of the basin during the last 10 Ma. The intensity of this activation is highest in the western part of the basin, where it is accompanied by the highest erosion amplitudes. The analysis of the variations in tectonic subsidence of the basement also suggests a series of intervals of lithospheric extension, which accounts for the stages of relatively rapid subsidence of the basin. Two intervals of significant extension of the lithosphere in the Upper Cretaceous and Paleocene are common for all areas within the basin. Here, the total amplitudes of the crustal extension attained 1.5 in the central part of the Sirte Basin (the Ajdabiya and Maradah troughs and Zelten and Dahra platforms

  15. Lithospheric structure, composition, and thermal regime of the East European Craton: Implications for the subsidence of the Russian platform

    USGS Publications Warehouse

    Artemieva, I.M.

    2003-01-01

    A new mechanism for Paleozoic subsidence of the Russian, or East European, platform is suggested, since a model of lithosphere tilting during the Uralian subduction does not explain the post-Uralian sedimentation record. Alternatively, I propose that the Proterozoic and Paleozoic rifting (when a platform-scale Central Russia rift system and a set of Paleozoic rifts were formed) modified the structure and composition of cratonic lithosphere, and these tectono-magmatic events are responsible for the post-Uralian subsidence of the Russian platform. To support this hypothesis, (a) the thermal regime and the thickness of the lithosphere are analyzed, and (b) lithospheric density variations of non-thermal origin are calculated from free-board constraints. The results indicate that Proterozoic and Paleozoic rifting had different effects on the lithospheric structure and composition. (1) Proterozoic rifting is not reflected in the present thermal regime and did not cause significant lithosphere thinning (most of the Russian platform has lithospheric thickness of 150-180 km and the lithosphere of the NE Baltic Shield is 250-300 km thick). Paleozoic rifting resulted in pronounced lithospheric thinning (to 120-140 km) in the southern parts of the Russian platform. (2) Lithospheric density anomalies suggest that Proterozoic-Paleozoic rifting played an important role in the platform subsidence. The lithospheric mantle of the Archean-early Proterozoic part of the Baltic Shield is ??? 1.4 ?? 0.2% less dense than the typical Phanerozoic upper mantle. However, the density deficit in the subcrustal lithosphere of most of the Russian platform is only about (0.4-0.8) ?? 0.2% and decreases southwards to ???0%. Increased densities (likely associated with low depletion values) in the Russian platform suggest strong metasomatism of the cratonic lithosphere during rifting events, which led to its subsidence. It is proposed that only the lower part of the cratonic lithosphere was

  16. Specific features of thermal regimes in rectangular laser slabs under steady-state pumping

    SciTech Connect

    Alpat'ev, A N; Smirnov, V A; Shcherbakov, Ivan A

    2010-01-31

    We continue to investigate the phenomena related to smoothing of temperature profiles in rectangular laser slabs and to an increase in the thresholds of their breakdown under optical pumping with variations in the slab optical density [the effect of smoothing of thermooptical inhomogeneities (STOI effect)]. It is found that the STOI effect is observed not only with increasing but also with decreasing optical density if this occurs due to a decrease in the sample thickness. The dependence of the maximum temperature difference inside the slab on its optical density at the instant of its thermal breakdown is calculated. It is shown that the variations in the optical density caused by variations in both the absorption coefficient and geometric dimensions of the slab differently affect the order of occurrence of two undesirable events - destruction of the slab or boiling of cooling water - with increasing pump power. The calculated relationships reveal two optical density regions corresponding to different orders of occurrence of these events. The maximum allowable temperatures in each region are determined. (active media)

  17. ACTIVE MEDIA: Specific features of thermal regimes in rectangular laser slabs under steady-state pumping

    NASA Astrophysics Data System (ADS)

    Alpat'ev, A. N.; Smirnov, V. A.; Shcherbakov, Ivan A.

    2010-01-01

    We continue to investigate the phenomena related to smoothing of temperature profiles in rectangular laser slabs and to an increase in the thresholds of their breakdown under optical pumping with variations in the slab optical density [the effect of smoothing of thermooptical inhomogeneities (STOI effect)]. It is found that the STOI effect is observed not only with increasing but also with decreasing optical density if this occurs due to a decrease in the sample thickness. The dependence of the maximum temperature difference inside the slab on its optical density at the instant of its thermal breakdown is calculated. It is shown that the variations in the optical density caused by variations in both the absorption coefficient and geometric dimensions of the slab differently affect the order of occurrence of two undesirable events — destruction of the slab or boiling of cooling water — with increasing pump power. The calculated relationships reveal two optical density regions corresponding to different orders of occurrence of these events. The maximum allowable temperatures in each region are determined.

  18. Thermal insights into the dynamics of Nyiragongo lava lake from ground and satellite measurements

    NASA Astrophysics Data System (ADS)

    Spampinato, L.; Ganci, G.; Hernández, P. A.; Calvo, D.; Tedesco, D.; Pérez, N. M.; Calvari, S.; Del Negro, C.; Yalire, M. M.

    2013-11-01

    present new insights into the short- and long-term thermal activity of the Nyiragongo lava lake by ground-based and satellite infrared thermal imagery recorded in the first half of 2012. This is the very first time in which FLIR camera and SEVIRI data have been compared at this volcano. Maximum temperatures recorded at the molten lava were of ~1180 K, whereas the lake skin remained always below ~734 K in areas far from the upwelling zone and below ~843 K in those proximal to the source region. Ground-based imagery yielded mean radiative power values between ~0.80 and 1.10 GW. Consistently, satellite observations showed similar mean values of 1.10 GW. Overall the thermal activity of the lava lake was quite variable along the three days of field measurements at both daily and intradaily scale. SEVIRI radiative power values retrieved for the January-June 2012 period revealed fluctuations within the same variability range suggesting that no significant changes of the lava lake area had occurred over the six months. Comparison with previous radiative power estimates showed that our data well agree with the general increasing trend recorded since the reappearance of the lava lake after the last flank eruption in 2002.

  19. A case for using ground-based thermal inertia measurements to detect Martian caves.

    PubMed

    Groemer, Gernot; Foresta, Luca; Turetschek, Thomas; Bothe, Claudia; Boyd, Andrea; Dinkelaker, Aline; Dissertori, Markus; Fasching, David; Fischer, Monika; Föger, Daniel; Frischauf, Norbert; Fritsch, Lukas; Fuchs, Harald; Gautsch, Christoph; Gerard, Stephan; Goetzloff, Linda; Gołebiowska, Izabella; Gorur, Paavan; Groemer, Gerhard; Groll, Petra; Haider, Christian; Haider, Olivia; Hauth, Eva; Hauth, Stefan; Hettrich, Sebastian; Jais, Wolfgang; Jones, Natalie; Taj-Eddine, Kamal; Karl, Alexander; Kauerhoff, Tilo; Khan, Muhammad Shadab; Kjeldsen, Andreas; Klauck, Jan; Losiak, Anna; Luger, Markus; Luger, Thomas; Luger, Ulrich; McArthur, Jane; Moser, Linda; Neuner, Julia; Orgel, Csilla; Ori, Gian Gabriele; Paternesi, Roberta; Peschier, Jarno; Pfeil, Isabella; Prock, Silvia; Radinger, Josef; Ragonig, Christoph; Ramirez, Barbara; Ramo, Wissam; Rampey, Mike; Sams, Arnold; Sams, Elisabeth; Sams, Sebastian; Sandu, Oana; Sans, Alejandra; Sansone, Petra; Scheer, Daniela; Schildhammer, Daniel; Scornet, Quentin; Sejkora, Nina; Soucek, Alexander; Stadler, Andrea; Stummer, Florian; Stumptner, Willibald; Taraba, Michael; Tlustos, Reinhard; Toferer, Ernst; Winter, Egon; Zanella-Kux, Katja

    2014-05-01

    Martian caves are regarded as one of the most interesting locations in which to search for life on the planet. Data obtained during the MARS2013 expedition at Hamar Laghdad Ridge in the Tafilalt region of Morocco indicate that even small cavities can display thermal behavior that is characteristic for caves. For example, temperature in a cavity equaled 14°C±0.1°C before sunrise, which was higher than the temperature of the ambient air (10°C±0.1°C) and proximate rocks (9°C±0.1°C) at the same time. Within 30 min after sunrise, when the temperature of surrounding rocks corresponded to 15°C, this thermal relationship reversed. Measurements were conducted under simulated spaceflight conditions, including near-real-time interpretation of data that were acquired in a complex flight planning environment. We conclude that using ground-based thermal contrast measurements, in 7-14 μm band before and after sunset, is an effective method for Mars astronauts to identify caves, possibly superior to usage of space-based or ground-penetrating data. PMID:24823802

  20. Hydrogeomorphic processes of thermokarst lakes with grounded-ice and floating-ice regimes on the Arctic coastal plain, Alaska

    USGS Publications Warehouse

    Arp, C.D.; Jones, Benjamin M.; Urban, F.E.; Grosse, G.

    2011-01-01

    Thermokarst lakes cover > 20% of the landscape throughout much of the Alaskan Arctic Coastal Plain (ACP) with shallow lakes freezing solid (grounded ice) and deeper lakes maintaining perennial liquid water (floating ice). Thus, lake depth relative to maximum ice thickness (1·5–2·0 m) represents an important threshold that impacts permafrost, aquatic habitat, and potentially geomorphic and hydrologic behaviour. We studied coupled hydrogeomorphic processes of 13 lakes representing a depth gradient across this threshold of maximum ice thickness by analysing remotely sensed, water quality, and climatic data over a 35-year period. Shoreline erosion rates due to permafrost degradation ranged from L) with periods of full and nearly dry basins. Shorter-term (2004–2008) specific conductance data indicated a drying pattern across lakes of all depths consistent with the long-term record for only shallow lakes. Our analysis suggests that grounded-ice lakes are ice-free on average 37 days longer than floating-ice lakes resulting in a longer period of evaporative loss and more frequent negative P − EL. These results suggest divergent hydrogeomorphic responses to a changing Arctic climate depending on the threshold created by water depth relative to maximum ice thickness in ACP lakes.

  1. High resolution characterization of northwest Mediterranean coastal waters thermal regimes: To better understand responses of benthic communities to climate change

    NASA Astrophysics Data System (ADS)

    Bensoussan, Nathaniel; Romano, Jean-Claude; Harmelin, Jean-Georges; Garrabou, Joaquim

    2010-04-01

    In the North West Mediterranean (NWM), mass mortality events (MME) of long-lived benthic species that have occurred over the last two decades have been related to regional warming trend. Gaining robust data sets on thermal regimes is critical to assess conditions to which species have adapted, detect extreme events and critically evaluate biological impacts. High resolution temperature ( T) time series obtained during 1999-2006 from 5 to 40 m depth at four contrasted sites of the NWM were analyzed: Area Marina Protegida de les Illes Medes (NE Spain), Riou (Marseilles, France), Parc National de Port-Cros (France), and Réserve Naturelle de Scandola (Corsica, France). The seasonal pattern showed winter T around 11-13 °C, and summer T mainly around 22-24 °C near surface to 18-20 °C at depth. Stratification dynamics showed recurrent downwellings (>40 m) at Medes, frequent observation (1/3rd of the summer) of deep and cold upwelled waters at Riou, while Scandola exhibited stable summer stratification and highest suprathermoclinal T. Port-Cros showed an intermediate regime that oscillated between Riou and Scandola depending on the occurrence of northern winds. Data distribution study permitted to identify and to characterize 3 large scale positive anomalies concomitant with the mass mortality outbreaks of summers 1999, 2003 and 2006. The analysis of biological surveys on gorgonian populations showed significant impacts during the 3 years with temperature anomalies. Besides the degree of impact showed inter-annual differences which could be related to different T conditions concomitant to mortality events, from slight increase in T extreme of only 1-2 °C over short duration, to lengthened more classical summer conditions. Our results therefore support the hypothesis that shallow NWM populations of long-lived benthic species are living near their upper thermal thresholds. Given actual trends and projections in NWM, the repetition of new MMEs in the next decades is

  2. MULTISPECTRAL THERMAL IMAGER SCIENCE, DATA PRODUCT AND GROUND DATA PROCESSING OVERVIEW.

    SciTech Connect

    J. SZYMANSKI; L. BALICK; ET AL

    2001-04-01

    The mission of the Multispectral Thermal Imager (MTI) satellite is to demonstrate the efficacy of highly accurate multispectral imaging for passive characterization of urban and industrial areas, as well as sites of environmental interest. The satellite makes top-of-atmosphere radiance measurements that are subsequently processed into estimates of surface properties such as vegetation health, temperatures, material composition and others. The system also provides simultaneous data for atmospheric characterization at high spatial resolution. To utilize these data the MTI science program has several coordinated components, including modeling, comprehensive ground-truth measurements, image acquisition planning, data processing and data analysis and interpretation . Algorithms have been developed to retrieve a multitude of physical quantities and these algorithms are integrated in a processing pipeline architecture that emphasizes automation, flexibility and programmability. This paper describes the MTI data products and ground processing, as well as the ''how to'' aspects of starting a data center from scratch.

  3. Cyclic CO2 emissions during the high temperature pulse of fluctuating thermal regime in eye-pigmented pupae of Megachile rotundata

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Megachile rotundata, the primary pollinator used in alfalfa seed production, may need to be exposed to low-temperature storage to slow the bees’ development to better match spring emergence with the alfalfa bloom. It has been demonstrated that using a fluctuating thermal regime (FTR) improves the be...

  4. Thermal performance of gaseous-helium-purged tank-mounted multilayer insulation system during ground-hold and space-hold thermal cycling and exposure to water vapor

    NASA Technical Reports Server (NTRS)

    Sumner, I. E.

    1978-01-01

    An experimental investigation was conducted to determine (1) the ground-hold and space-hold thermal performance of a multilayer insulation (MLI) system mounted on a spherical, liquid-hydrogen propellant tank and (2) the degradation to the space-hold thermal performance of the insulation system that resulted from both thermal cycling and exposure to moisture. The propellant tank had a diameter of 1.39 meters (4.57ft). The MLI consisted of two blankets of insulation; each blanket contained 15 double-aluminized Mylar radiation shields separated by double silk net spacers. Nineteen tests simulating basic cryogenic spacecraft thermal (environmental) conditions were conducted. These tests typically included initial helium purge, liquid-hydrogen fill and ground-hold, ascent, space-hold, and repressurization. No significant degradation of the space-hold thermal performance due to thermal cycling was noted.

  5. Phonon-engineered thermal transport in Si wires with constant and periodically modulated cross-sections: A crossover between nano- and microscale regimes

    NASA Astrophysics Data System (ADS)

    Cocemasov, A. I.; Nika, D. L.; Fomin, V. M.; Grimm, D.; Schmidt, O. G.

    2015-07-01

    The transition between nanoscale and microscale thermal transport regime at room temperature in silicon wires with constant and periodically modulated cross-section is theoretically investigated. Extrapolating the calculated thermal conductivity from the nano- to micrometer range, we find the characteristic dimensions of the wires where a crossover between nanoscale and microscale thermal transport occurs. This crossover is observed in both generic (smooth) and cross-section-modulated wires. In case of smooth silicon wires, we reveal a strong dependence of the crossing point position on the boundary roughness. For silicon wires with weak boundary roughness, the crossover occurs at cross-sections ˜60 nm × 300 nm, while for very rough boundaries it occurs at cross-sections ˜150 nm × 750 nm. In case of the periodically modulated wires, the crossover between nano- and microscale regimes occurs at typical cross-sections ˜120 nm × 120 nm of the narrow segment, and it is almost independent of boundary roughness. A strong distinction from the case of smooth wires is attributed (i) to the different trends at the nanometer scale, wherefrom the extrapolation was performed, and (ii) to the different phonon-boundary scattering due to the specific geometry. For modulated silicon wires, the influence of modulation thickness, modulation length, and cross-sectional area on the phonon thermal conductivity at the room temperature is analyzed. A possibility of thermal transport engineering in cross-section-modulated wires by resizing them is revealed in both nano- and microscale regimes. The presented results pave the way towards a better understanding of thermal transport reduction in Si nanowires with engineered diameter modulations and shed light on the crossover between nano- and microscale regimes of thermal transport.

  6. Thermal power and heat energy of cloud-to-ground lightning process

    NASA Astrophysics Data System (ADS)

    Wang, Xuejuan; Yuan, Ping; Cen, Jianyong; Xue, Simin

    2016-07-01

    A cloud-to-ground lightning flash with nine return strokes has been recorded using a high speed slitless spectrograph and a system composed of a fast antenna and a slow antenna. Based on the spectral data and the synchronous electric field changes that were caused by the lightning, the electrical conductivity, the channel radii, the resistance per unit length, the peak current, the thermal power at the instant of peak current, and the heat energy per unit length during the first 5 μs in the discharge channel have all been calculated. The results indicate that the channel radii have linear relationships with the peak current. The thermal power at the peak current time increases with increasing resistance, but exponential decays with the square of the peak current.

  7. Use of thermal-infrared imagery in ground-water investigations in Montana

    NASA Technical Reports Server (NTRS)

    Boettcher, A. J.; Haralick, R. M.

    1977-01-01

    Thermal infrared imagery was used to locate ground-water inflow along three streams and one lake in Montana. The thermal scanner used in May 1972, March 1973, and November 1975 was mounted in a twin-engined aircraft. On the 1973 and 1975 flights, the data were recorded in an analog format on magnetic tape in flight, later were converted to digital format, and were computer processed using an assignment of patterns to indicate differences in water temperature. Output from the image processing program was converted to a temperature map having an isotherm spacing of 0.5 C. Computerization was found to be the most efficient method to manipulate data from lakes, large rivers, and narrow sinuous streams.

  8. THERMAL ESCAPE IN THE HYDRODYNAMIC REGIME: RECONSIDERATION OF PARKER's ISENTROPIC THEORY BASED ON RESULTS OF KINETIC SIMULATIONS

    SciTech Connect

    Volkov, Alexey N.; Johnson, Robert E.

    2013-03-10

    The one-dimensional steady-state problem of thermal escape from a single-component atmosphere of mon- and diatomic gases is studied in the hydrodynamic (blow-off) regime using the direct simulation Monte Carlo method for an evaporative-type condition at the lower boundary. The simulations are performed for various depths into an atmosphere, indicated by a Knudsen number, Kn{sub 0}, equal to the ratio of the mean free path of molecules to the radial position of the source surface, ranging from 10 to 10{sup -5}, and for the range of the source Jeans parameter, {lambda}{sub 0}, equal to the ratio of gravitational and thermal energies, specific to blow-off. The results of kinetic simulations are compared with the isentropic model (IM) and the Navier-Stokes model. It is shown that the IM can be simplified if formulated in terms of the local Mach number and Jeans parameter. The simulations predict that at Kn{sub 0} < {approx} 10{sup -3} the flow includes a near-surface non-equilibrium Knudsen layer, a zone where the flow can be well approximated by the IM, and a rarefied far field. The corresponding IM solutions, however, only approach Parker's critical solution as {lambda}{sub 0} approaches the upper limit for blow-off. The IM alone is not capable for predicting the flow and requires boundary conditions at the top of the Knudsen layer. For small Kn{sub 0}, the scaled escape rate and energy loss rate are found to be independent of {lambda}{sub 0}. The simulation results can be scaled to any single-component atmosphere exhibiting blow-off if the external heating above the lower boundary is negligible, in particular, to sublimation-driven atmospheres of Kuiper belt objects.

  9. Testing the reference Moon model in respect of the thermal regime and chemical composition of the mantle: Thermodynamics versus seismology

    NASA Astrophysics Data System (ADS)

    Kuskov, O. L.; Kronrod, V. A.; Kronrod, E. V.

    2016-05-01

    The VPREMOON seismic reference Moon model (Garcia et al., 2011) has been tested with respect to the thermal regime and chemical composition of the mantle. Based on a self-consistent thermodynamic approach and petrological models of the lunar mantle covering a wide range of concentrations of CaO, Al2O3, and FeO, we convert the P- and S-wave velocity profiles to the temperature-depth profiles. The solution procedure relies on the method of the Gibbs free energy minimization and the equations of state for the mantle material which take into account the effects of phase transformations, anharmonicity, and anelasticity. We find that regardless of the chemical composition, the positive P- and S-wave velocity gradient in the lunar mantle leads to a negative temperature gradient, which has no physical basis. For adequate mantle temperatures, the P- and S-wave velocities should remain almost constant or slightly decrease with depth (especially V S ) as a result of the effects of the temperature, which grows faster than pressure. These findings underscore the importance of the relationship of the thermodynamics and physics of minerals with seismology.

  10. Thermal Contributions to the Degradation of Ground-Laboratory- and Space-Irradiated Teflon Investigated

    NASA Technical Reports Server (NTRS)

    deGroh, Kim K.; Martin, Morgana

    2003-01-01

    The Hubble Space Telescope (HST) is covered with two primary types of thermal control materials, radiators and multilayer insulation blankets, which passively control temperatures during orbit. Both of these thermal control materials utilize back-surface metalized Teflon FEP (DuPont, fluorinated ethylene propylene) as the exterior (spacefacing) layer because of its excellent optical properties (low solar absorptance and high thermal emittance). The aluminized-FEP (Al-FEP) outermost layer of the multilayer insulation blankets on the HST has become embrittled while in space, resulting in severe on-orbit cracking (see the photographs). During the second servicing mission, an extremely embrittled piece of Al-FEP was retrieved that had curled, exposing the backsurface aluminum to space (see the photograph on the right). Because the aluminum surface has a lower thermal emittance than the FEP, this curled piece reached 200 C during orbit, 150 C higher than the nominal temperature extreme. To better understand the effect of temperature on the rate of degradation, and on the mechanism of degradation, of this insulation material in the low-Earth-orbit environment, researchers at the NASA Glenn Research Center conducted experiments to determine the effect of heating on the degradation of FEP that has been irradiated in a ground laboratory facility or in space on the HST. For this study, Teflon FEP retrieved from the HST during the third servicing mission after 9.7 years of space exposure was provided to Glenn by the NASA Goddard Space Flight Center.

  11. SWIFT BAT Loop Heat Pipe Thermal System Characteristics and Ground/Flight Operation Procedure

    NASA Technical Reports Server (NTRS)

    Choi, Michael K.

    2003-01-01

    The SWIFT Burst Alert Telescope (BAT) Detector Array has a total power dissipation of 208 W. To meet the stringent temperature gradient and thermal stability requirements in the normal operational mode, and heater power budget in both the normal operational and safehold modes, the Detector Array is thermally well coupled to eight constant conductance heat pipes (CCHPs) embedded in the Detector Array Plate (DAP), and two loop heat pipes (LHPs) transport heat fiom the CCHPs to a radiator. The CCHPs have ammonia as the working fluid and the LHPs have propylene as the working fluid. Precision heater controllers, which have adjustable set points in flight, are used to control the LHP compensation chamber and Detector Array XA1 ASIC temperatures. The radiator has the AZ-Tek AZW-LA-II low-alpha white paint as the thermal coating and is located on the anti-sun side of the spacecraft. This paper presents the characteristics, ground operation and flight operation procedures of the LHP thermal system.

  12. Urban Soil: Assessing Ground Cover Impact on Surface Temperature and Thermal Comfort.

    PubMed

    Brandani, Giada; Napoli, Marco; Massetti, Luciano; Petralli, Martina; Orlandini, Simone

    2016-01-01

    The urban population growth, together with the contemporary deindustrialization of metropolitan areas, has resulted in a large amount of available land with new possible uses. It is well known that urban green areas provide several benefits in the surrounding environment, such as the improvement of thermal comfort conditions for the population during summer heat waves. The purpose of this study is to provide useful information on thermal regimes of urban soils to urban planners to be used during an urban transformation to mitigate surface temperatures and improve human thermal comfort. Field measurements of solar radiation, surface temperature (), air temperature (), relative humidity, and wind speed were collected on four types of urban soils and pavements in the city of Florence during summer 2014. Analysis of days under calm, clear-sky condition is reported. During daytime, sun-to-shadow differences for , apparent temperature index (ATI), and were significantly positive for all surfaces. Conversely, during nighttime, differences among all surfaces were significantly negative, whereas ATI showed significantly positive differences. Moreover, was significantly negative for grass and gravel. Relative to the shaded surfaces, was higher on white gravel and grass than gray sandstone and asphalt during nighttime, whereas gray sandstone was always the warmest surface during daytime. Conversely, no differences were found during nighttime for ATI and measured over surfaces that were exposed to sun during the day, whereas showed higher values on gravel than grass and asphalt during nighttime. An exposed surface warms less if its albedo is high, leading to a significant reduction of during daytime. These results underline the importance of considering the effects of surface characteristics on surface temperature and thermal comfort. This would be fundamental for addressing urban environment issues toward the heat island mitigation considering also the impact of urban

  13. Analyzing the discharge regime of a large tropical river through remote sensing, ground-based climatic data, and modeling

    NASA Astrophysics Data System (ADS)

    VöRöSmarty, Charles J.; Willmott, Cort J.; Choudhury, Bhaskar J.; Schloss, Annette L.; Stearns, Timothy K.; Robeson, Scott M.; Dorman, Timothy J.

    1996-10-01

    This study demonstrates the potential for applying passive microwave satellite sensor data to infer the discharge dynamics of large river systems using the main stem Amazon as a test case. The methodology combines (1) interpolated ground-based meteorological station data, (2) horizontally and vertically polarized temperature differences (HVPTD) from the 37-GHz scanning multichannel microwave radiometer (SMMR) aboard the Nimbus 7 satellite, and (3) a calibrated water balance/water transport model (WBM/WTM). Monthly HVPTD values at 0.25° (latitude by longitude) resolution were resampled spatially and temporally to produce an enhanced HVPTD time series at 0.5° resolution for the period May 1979 through February 1985. Enhanced HVPTD values were regressed against monthly discharge derived from the WBM/WTM for each of 40 grid cells along the main stem over a calibration period from May 1979 to February 1983 to provide a spatially contiguous estimate of time-varying discharge. HVPTD-estimated flows generated for a validation period from March 1983 to February 1985 were found to be in good agreement with both observed arid modeled discharges over a 1400-km section of the main stem Amazon. This span of river is bounded downstream by a region of tidal influence and upstream by low sensor response associated with dense forest canopy. Both the WBM/WTM and HVPTD-derived flow rates reflect the significant impact of the 1982-1983 El Niño-;Southern Oscillation (ENSO) event on water balances within the drainage basin.

  14. Statistical significant changes in ground thermal conditions of alpine Austria during the last decade

    NASA Astrophysics Data System (ADS)

    Kellerer-Pirklbauer, Andreas

    2016-04-01

    Longer data series (e.g. >10 a) of ground temperatures in alpine regions are helpful to improve the understanding regarding the effects of present climate change on distribution and thermal characteristics of seasonal frost- and permafrost-affected areas. Beginning in 2004 - and more intensively since 2006 - a permafrost and seasonal frost monitoring network was established in Central and Eastern Austria by the University of Graz. This network consists of c.60 ground temperature (surface and near-surface) monitoring sites which are located at 1922-3002 m a.s.l., at latitude 46°55'-47°22'N and at longitude 12°44'-14°41'E. These data allow conclusions about general ground thermal conditions, potential permafrost occurrence, trend during the observation period, and regional pattern of changes. Calculations and analyses of several different temperature-related parameters were accomplished. At an annual scale a region-wide statistical significant warming during the observation period was revealed by e.g. an increase in mean annual temperature values (mean, maximum) or the significant lowering of the surface frost number (F+). At a seasonal scale no significant trend of any temperature-related parameter was in most cases revealed for spring (MAM) and autumn (SON). Winter (DJF) shows only a weak warming. In contrast, the summer (JJA) season reveals in general a significant warming as confirmed by several different temperature-related parameters such as e.g. mean seasonal temperature, number of thawing degree days, number of freezing degree days, or days without night frost. On a monthly basis August shows the statistically most robust and strongest warming of all months, although regional differences occur. Despite the fact that the general ground temperature warming during the last decade is confirmed by the field data in the study region, complications in trend analyses arise by temperature anomalies (e.g. warm winter 2006/07) or substantial variations in the winter

  15. Distribution of Io's Volcanic Thermal Emission From Galileo and Ground-Based Data

    NASA Astrophysics Data System (ADS)

    Veeder, G. J.; Davies, A. G.; Matson, D.; Johnson, T. V.; Williams, D. A.; Radebaugh, J.

    2011-12-01

    Detections of Io's hot spots and identification of volcanic features have been catalogued by various workers [e.g., 1-4]. However, to understand the role played by volcanism in global heat transport, thermal emission from Io's volcanoes has to be quantified, locally, regionally and globally. Only then can robust estimates be made of volcanic advection, which may reveal internal heating patterns controlled by the evolving tidal resonance between Io, Europa and Ganymede. We have completed an analysis of all suitable spacecraft data and, using additional ground-based data, have quantified the thermal emission from all of Io's volcanoes during the Galileo epoch down to the limit of detection [5-7]. Galileo identified many dark features on Io that did not exhibit obvious anomalous thermal emission, yet their low albedo suggested that these features were at least warm (cool, high albedo sulphurous deposits had not formed on them). We used dark areas identified from the recently-published Io Global Map [3] and a knowledge of the detection limit of the Galileo NIMS instrument to quantify the thermal emission from these areas. In all, our analysis includes 272 individual thermal sources yielding ~60 TW. Our "snapshot" of global volcanic activity shows that Io's paterae yield ~80% of this amount, with a preponderance of thermal emission emanating from the northern hemisphere. This is strongly biased by Loki Patera and, to a lesser extent, by recent outburst locations. Of the remaining identified hot spot thermal emission, ~15% comes from active or recent lava flow fields, and the remaining 5% comes from massive outburst eruptions (some in paterae) and very small hot spots. The energy accounted for makes up ~60% of Io's total thermal emission of ~100 TW [8]. It is possible that a multitude of very small hot spots beneath instrument detection limits, and/or cooler, secondary volcanic processes involving sulphurous compounds may be responsible for the unaccounted heat flow

  16. Survival, development, and growth of fall Chinook salmon embryos, alevin, and fry exposed to variable thermal and dissolved oxygen regimes

    SciTech Connect

    Geist, David R.; Abernethy, Cary S.; Hand, Kristine D.; Cullinan, Valerie I.; Chandler, James A.; Groves, Philip

    2006-11-15

    Some fall Chinook salmon (Oncorhynchus tshawytscha) initiate spawning in the Snake River downstream of Hells Canyon Dam at temperatures that exceed 13?C and at intergravel dissolved oxygen concentrations that are less than 8 mg O2/L. Although water temperature declines and dissolved oxygen increases soon after spawning, these temperature and dissolved oxygen levels do not meet the water quality standards established by the states of Oregon and Idaho for salmonid spawning. Our objective was to determine if temperatures from 13 to 17 C and dissolved oxygen levels from 4 to greater than 8 mg O2/L during the first 40 days of incubation followed by declining temperature and rising dissolved oxygen affected survival, development, and growth of Snake River fall Chinook salmon embryos, alevins, and fry. During the first 40 days of incubation, temperatures were adjusted downward approximately 0.2 C/day and oxygen was increased in increments of 2 mg O2/L to mimic the thermal and oxygen regime of the Snake River where these fish spawn. At 40 days post-fertilization, embryos were moved to a common exposure regime that followed the thermal and dissolved oxygen profile of the Snake River through emergence. Mortality of fall Chinook salmon embryos increased markedly at initial incubation temperatures equal to or greater than 17?C, and a rapid decline in survival occurred between 16.5 C and 17 C, with no significant difference in survival at temperatures less than or equal to 16.5 C. Initial dissolved oxygen levels as low as 4 mg O2/L over a range of initial temperatures from 15 to 16.5 C did not affect embryo survival to emergence. There were no significant differences across the range of initial temperature exposures for alevin and fry size at hatch and emergence. The number of days from fertilization to eyed egg, hatch, and emergence was highly related to temperature and dissolved oxygen; it took from 6 to 10 days longer to reach hatch at 4 mg O2/L than at saturation and up to

  17. An epidemic model for the interactions between thermal regime of rivers and transmission of Proliferative Kidney Disease in salmonid fish

    NASA Astrophysics Data System (ADS)

    Carraro, Luca; Bertuzzo, Enrico; Mari, Lorenzo; Gatto, Marino; Strepparava, Nicole; Hartikainen, Hanna; Rinaldo, Andrea

    2015-04-01

    Proliferative kidney disease (PKD) affects salmonid populations in European and North-American rivers. It is caused by the endoparasitic myxozoan Tetracapsuloides bryosalmonae, which exploits freshwater bryozoans (Fredericella sultana) and salmonids as primary and secondary hosts, respectively. Incidence and mortality, which can reach up to 90-100%, are known to be strongly related to water temperature. PKD has been present in brown trout population for a long time but has recently increased rapidly in incidence and severity causing a decline in fish catches in many countries. In addition, environmental changes are feared to cause PKD outbreaks at higher latitude and altitude regions as warmer temperatures promote disease development. This calls for a better comprehension of the interactions between disease dynamics and the thermal regime of rivers, in order to possibly devise strategies for disease management. In this perspective, a spatially explicit model of PKD epidemiology in riverine host metacommunities is proposed. The model aims at summarizing the knowledge on the modes of transmission of the disease and the life-cycle of the parasite, making the connection between temperature and epidemiological parameters explicit. The model accounts for both local population and disease dynamics of bryozoans and fish and hydrodynamic dispersion of the parasite spores and hosts along the river network. The model is time-hybrid, coupling inter-seasonal and intra-seasonal dynamics, the former being described in a continuous time domain, the latter seen as time steps of a discrete time domain. In order to test the model, a case study is conducted in river Wigger (Cantons of Aargau and Lucerne, Switzerland), where data about water temperature, brown trout and bryozoan populations and PKD prevalence are being collected.

  18. Aerothermal Ground Testing of Flexible Thermal Protection Systems for Hypersonic Inflatable Aerodynamic Decelerators

    NASA Technical Reports Server (NTRS)

    Bruce, Walter E., III; Mesick, Nathaniel J.; Ferlemann, Paul G.; Siemers, Paul M., III; DelCorso, Joseph A.; Hughes, Stephen J.; Tobin, Steven A.; Kardell, Matthew P.

    2012-01-01

    Flexible TPS development involves ground testing and analysis necessary to characterize performance of the FTPS candidates prior to flight testing. This paper provides an overview of the analysis and ground testing efforts performed over the last year at the NASA Langley Research Center and in the Boeing Large-Core Arc Tunnel (LCAT). In the LCAT test series, material layups were subjected to aerothermal loads commensurate with peak re-entry conditions enveloping a range of HIAD mission trajectories. The FTPS layups were tested over a heat flux range from 20 to 50 W/cm with associated surface pressures of 3 to 8 kPa. To support the testing effort a significant redesign of the existing shear (wedge) model holder from previous testing efforts was undertaken to develop a new test technique for supporting and evaluating the FTPS in the high-temperature, arc jet flow. Since the FTPS test samples typically experience a geometry change during testing, computational fluid dynamic (CFD) models of the arc jet flow field and test model were developed to support the testing effort. The CFD results were used to help determine the test conditions experienced by the test samples as the surface geometry changes. This paper includes an overview of the Boeing LCAT facility, the general approach for testing FTPS, CFD analysis methodology and results, model holder design and test methodology, and selected thermal results of several FTPS layups.

  19. Ground Laboratory Soft X-Ray Durability Evaluation of Aluminized Teflon FEP Thermal Control Insulation. Revised

    NASA Technical Reports Server (NTRS)

    Banks, Bruce A.; deGroh, Kim K.; Stueber, Thomas J.; Sechkar, Edward A.; Hall, Rachelle L.

    1998-01-01

    Metallized Teflon fluorinated ethylene propylene (FEP) thermal control insulation is mechanically degraded if exposed to a sufficient fluence of soft x-ray radiation. Soft x-ray photons (4-8 A in wavelength or 1.55 - 3.2 keV) emitted during solar flares have been proposed as a cause of mechanical properties degradation of aluminized Teflon FEP thermal control insulation on the Hubble Space Telescope (HST). Such degradation can be characterized by a reduction in elongation-to-failure of the Teflon FEP. Ground laboratory soft x-ray exposure tests of aluminized Teflon FEP were conducted to assess the degree of elongation degradation which would occur as a result of exposure to soft x-rays in the range of 3-10 keV. Tests results indicate that soft x-ray exposure in the 3-10 keV range, at mission fluence levels, does not alone cause the observed reduction in elongation of flight retrieved samples. The soft x-ray exposure facility design, mechanical properties degradation results and implications will be presented.

  20. Ground Laboratory Soft X-Ray Durability Evaluation of Aluminized Teflon FEP Thermal Control Insulation

    NASA Technical Reports Server (NTRS)

    Banks, Bruce A.; deGroh, Kim K.; Stueber, Thomas J.; Sechkar, Edward A.

    1998-01-01

    Metallized Teflon fluorinated ethylene propylene (FEP) thermal control insulation is mechanically degraded if exposed to a sufficient fluence of soft x-ray radiation. Soft x-ray photons (4-8 A in wavelength or 1.55 - 3.2 keV) emitted during solar flares have been proposed as a cause of mechanical properties degradation of aluminized Teflon FEP thermal control insulation on the Hubble Space Telescope (HST). Such degradation can be characterized by a reduction in elongation-to-failure of the Teflon FER Ground laboratory soft x-ray exposure tests of aluminized Teflon FEP were conducted to assess the degree of elongation degradation which would occur as a result of exposure to soft x-rays in the range of 3-10 keV. Tests results indicate that soft x-ray exposure in the 3-10 keV range, at mission fluence levels, does not alone cause the observed reduction in elongation of flight retrieved samples. The soft x-ray exposure facility design, mechanical properties degradation results and implications will be presented.

  1. Advanced Coupled Simulation of Borehole Thermal Energy Storage Systems and Above Ground Installations

    NASA Astrophysics Data System (ADS)

    Welsch, Bastian; Rühaak, Wolfram; Schulte, Daniel O.; Bär, Kristian; Sass, Ingo

    2016-04-01

    Seasonal thermal energy storage in borehole heat exchanger arrays is a promising technology to reduce primary energy consumption and carbon dioxide emissions. These systems usually consist of several subsystems like the heat source (e.g. solarthermics or a combined heat and power plant), the heat consumer (e.g. a heating system), diurnal storages (i.e. water tanks), the borehole thermal energy storage, additional heat sources for peak load coverage (e.g. a heat pump or a gas boiler) and the distribution network. For the design of an integrated system, numerical simulations of all subsystems are imperative. A separate simulation of the borehole energy storage is well-established but represents a simplification. In reality, the subsystems interact with each other. The fluid temperatures of the heat generation system, the heating system and the underground storage are interdependent and affect the performance of each subsystem. To take into account these interdependencies, we coupled a software for the simulation of the above ground facilities with a finite element software for the modeling of the heat flow in the subsurface and the borehole heat exchangers. This allows for a more realistic view on the entire system. Consequently, a finer adjustment of the system components and a more precise prognosis of the system's performance can be ensured.

  2. Comparison of Thermal Structure Results from Venus Express and Ground Based Observations since Vira

    NASA Astrophysics Data System (ADS)

    Limaye, Sanjay

    2016-07-01

    An international team was formed in 2013 through the International Space Studies Institute (Bern, Switzerland) to compare recent results of the Venus atmospheric thermal structure from spacecraft and ground based observations made since the Venus International Reference Atmosphere (VIRA) was developed (Kliore et al., 1985, Keating et al., 1985). Five experiments on European Space Agency's Venus Express orbiter mission have yielded results on the atmospheric structure during is operational life (April 2006 - November 2014). Three of these were from occultation methods: at near infrared wavelengths from solar occultations, (SOIR, 70 - 170 km), at ultraviolet wavelengths from stellar occultations (SPICAV, 90-140 km), and occultation of the VEx-Earth radio signal (VeRa, 40-90 km). In-situ drag measurements from three different techniques (accelerometry, torque, and radio tracking, 130 - 200 km) were also obtained using the spacecraft itself while passive infrared remote sensing was used by the VIRTIS experiment (70 - 120 km). The only new data in the -40-70 km altitude range are from radio occultation, as no new profiles of the deep atmosphere have been obtained since the VeGa 2 lander measurements in 1985 (not included in VIRA). Some selected ground based results available to the team were also considered by team in the inter comparisons. The temperature structure in the lower thermosphere from disk resolved ground based observations (except for one ground based investigation), is generally consistent with the Venus Express results. These experiments sampled at different periods, at different locations and at different local times and have different vertical and horizontal resolution and coverage. The data were therefore binned in latitude and local time bins and compared, ignoring temporal variations over the life time of the Venus Express mission and assumed north-south symmetry. Alternating warm and cooler layers are present in the 120-160 altitude range in results

  3. The Influences of Land Surface Properties on Soil Thermal Regimes in the Low Arctic of Northwestern Siberia

    NASA Astrophysics Data System (ADS)

    Epstein, H. E.; Frost, G. V., Jr.; Matyshak, G. V.; Walker, D. A.; Meakem, V. M.

    2014-12-01

    Understanding the feedbacks among climate, permafrost, and vegetation is crucial for assessments of arctic ecosystem vulnerability and response to climate change, and for development of sustainable engineering and management methods associated with infrastructure. Vegetation, snow cover, and near-surface soil organic layers are key determinants in regulating the energy exchange between the atmosphere and the deeper soils. Here we present high-temporal resolution soil thermal regime data over annual time extents for multiple sites at two locations in the Low Arctic of northwestern Siberia. At a location near Nadym, Russia, we measured soil temperatures at various depths in the soil profile (down to 60 cm) at three sites: 1) a boreal forest stand with lichen understory and a shallow organic layer (8 cm), 2) a young, cryoturbated Sphagnum peatland with soil organic layers to 40 cm depth, and 3) an old Sphagnum peatland with deep organic soil horizons (58+ cm). At a location near Kharp, Russia, we measured soil temperatures at 5 and 20 cm depth for sites along a chronosequence of tall alder shrub expansion, from short-statured tundra to mature and old alder stands, with deeper organic layers. The deeper snow accumulation at the Nadym forest site kept winter soil temperatures dramatically warmer than the peatland soils, up to 8 °C difference, but the shading of the forest tended to cool the surface during the summer. The overall effect of the forest was cooler summer soils in the near-surface layers, yet warmer summer soils at the deeper layers (20-60 cm). The forest location had substantially greater thawing degree days at depth (20-60 cm), compared to the Sphagnum peatlands. At the Kharp site, mature alder shrub stands cooled summer soil temperatures relative to shorter tundra by up to 8 °C (at 20 cm depth), yet warmed winter soils by greater than 10 °C. Mature and old shrubland locations had reduced thawing degree days at 20 cm depth relative to short

  4. Correcting atmospheric effects in thermal ground observations for hyperspectral emissivity estimation

    NASA Astrophysics Data System (ADS)

    Timmermans, Joris; Buitrago, Maria

    2014-05-01

    Knowledge of Land surface temperature is of crucial importance in energy balance studies and environmental modeling. Accurate retrieval of land surface temperature (LST) demands detailed knowledge of the land surface emissivity. Measured radiation by remote sensing sensors to land surface temperature can only be performed using a-priori knowledge of the emissivity. Uncertainties in the retrieval of this emissivity can cause huge errors in LST estimations. The retrieval of emissivity (and LST) is per definition an underdetermined inversion, as only one observation is made while two variables are to be estimated. Several researches have therefore been performed on measuring emissivity, such as the normalized emissivity method, the temperature-emissivity separation (TES) using the minimum and maximum difference of emissivity and the use of vegetation indices. In each of these approaches atmospherically corrected radiance measurements by remote sensing sensors are correlated to ground measurements. Usually these ground measurements are performed with the ground equivalent of the remote sensing sensors; the CIMEL 312-2 has the same spectral bands as ASTER. This way parameterizations acquired this way are only usable for specific sensors and need to be redone for newer sensors. Recently hyperspectral thermal radiometers, such as the MIDAC, have been developed that can solve this problem. By using hyperspectral observations of emissivity, together with sensor simulators, ground measurements of different satellite sensor can be simulated. This facilitates the production of validation data for the different TES algorithms. However before such measurements can be performed extra steps of processing need to be performed. Atmospheric correction becomes more important in hyperspectral observations than for broadband observations, as energy levels measured per band is lower. As such the atmosphere has a relative larger contribution if bandwidths become smaller. The goal of this

  5. Ground surface temperature reconstructions: Using in situ estimates for thermal conductivity acquired with a fiber-optic distributed thermal perturbation sensor

    SciTech Connect

    Freifeld, B.M.; Finsterle, S.; Onstott, T.C.; Toole, P.; Pratt, L.M.

    2008-10-10

    We have developed a borehole methodology to estimate formation thermal conductivity in situ with a spatial resolution of one meter. In parallel with a fiber-optic distributed temperature sensor (DTS), a resistance heater is deployed to create a controlled thermal perturbation. The transient thermal data is inverted to estimate the formation's thermal conductivity. We refer to this instrumentation as a Distributed Thermal Perturbation Sensor (DTPS), given the distributed nature of the DTS measurement technology. The DTPS was deployed in permafrost at the High Lake Project Site (67 degrees 22 minutes N, 110 degrees 50 minutes W), Nunavut, Canada. Based on DTPS data, a thermal conductivity profile was estimated along the length of a wellbore. Using the thermal conductivity profile, the baseline geothermal profile was then inverted to estimate a ground surface temperature history (GSTH) for the High Lake region. The GSTH exhibits a 100-year long warming trend, with a present-day ground surface temperature increase of 3.0 {+-} 0.8 C over the long-term average.

  6. Thermal inactivation of Bacillus anthracis Sterne in irradiated ground beef heated in a water bath or cooked on commercial grills

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The thermal stability of heat-shocked and non heat-shocked spores of the virulence-attenuated Sterne strain of Bacillus anthracis was evaluated at select temperatures in irradiated, raw ground beef (25% fat) heated in a water bath or cooked using two different commercial grills. For the former, 3-g ...

  7. Ground Boundary Conditions for Thermal Convection Over Horizontal Surfaces at High Rayleigh Numbers

    NASA Astrophysics Data System (ADS)

    Hanjalić, K.; Hrebtov, M.

    2016-07-01

    We present "wall functions" for treating the ground boundary conditions in the computation of thermal convection over horizontal surfaces at high Rayleigh numbers using coarse numerical grids. The functions are formulated for an algebraic-flux model closed by transport equations for the turbulence kinetic energy, its dissipation rate and scalar variance, but could also be applied to other turbulence models. The three-equation algebraic-flux model, solved in a T-RANS mode ("Transient" Reynolds-averaged Navier-Stokes, based on triple decomposition), was shown earlier to reproduce well a number of generic buoyancy-driven flows over heated surfaces, albeit by integrating equations up to the wall. Here we show that by using a set of wall functions satisfactory results are found for the ensemble-averaged properties even on a very coarse computational grid. This is illustrated by the computations of the time evolution of a penetrative mixed layer and Rayleigh-Bénard (open-ended, 4:4:1 domain) convection, using 10 × 10 × 100 and 10 × 10 × 20 grids, compared also with finer grids (e.g. 60 × 60 × 100), as well as with one-dimensional treatment using 1 × 1 × 100 and 1 × 1 × 20 nodes. The approach is deemed functional for simulations of a convective boundary layer and mesoscale atmospheric flows, and pollutant transport over realistic complex hilly terrain with heat islands, urban and natural canopies, for diurnal cycles, or subjected to other time and space variations in ground conditions and stratification.

  8. Ground Boundary Conditions for Thermal Convection Over Horizontal Surfaces at High Rayleigh Numbers

    NASA Astrophysics Data System (ADS)

    Hanjalić, K.; Hrebtov, M.

    2016-02-01

    We present "wall functions" for treating the ground boundary conditions in the computation of thermal convection over horizontal surfaces at high Rayleigh numbers using coarse numerical grids. The functions are formulated for an algebraic-flux model closed by transport equations for the turbulence kinetic energy, its dissipation rate and scalar variance, but could also be applied to other turbulence models. The three-equation algebraic-flux model, solved in a T-RANS mode ("Transient" Reynolds-averaged Navier-Stokes, based on triple decomposition), was shown earlier to reproduce well a number of generic buoyancy-driven flows over heated surfaces, albeit by integrating equations up to the wall. Here we show that by using a set of wall functions satisfactory results are found for the ensemble-averaged properties even on a very coarse computational grid. This is illustrated by the computations of the time evolution of a penetrative mixed layer and Rayleigh-Bénard (open-ended, 4:4:1 domain) convection, using 10 × 10 × 100 and 10 × 10 × 20 grids, compared also with finer grids (e.g. 60 × 60 × 100 ), as well as with one-dimensional treatment using 1 × 1 × 100 and 1 × 1 × 20 nodes. The approach is deemed functional for simulations of a convective boundary layer and mesoscale atmospheric flows, and pollutant transport over realistic complex hilly terrain with heat islands, urban and natural canopies, for diurnal cycles, or subjected to other time and space variations in ground conditions and stratification.

  9. IAP RAS microwave radiometry complex: sounding atmospheric thermal structure from the ground up to 55km.

    NASA Astrophysics Data System (ADS)

    Belikovich, Mikhail; Shvetsov, Alexander; Ryskin, Vitaly; Mukhin, Dmitry; Kulikov, Mikhail; Feigin, Alexander

    2016-04-01

    Thermal structure is the key characteristic of the atmosphere. Depending on the altitude, it is measured by different methods. In troposphere a plethora of in-situ techniques exists while in middle atmosphere remote sensing is primary type of measurement. The remote sensing is conducted in different wavelengths: optical, infrared and microwave. Satellite based measurements are the most popular kind of remote sensing measurements as it provides global coverage. Ground based passive microwave remote sensing technique has its place when one need permanent monitoring with high time resolution in order to study short-term local events like gravity waves. Institute of Applied Physics of the Russian Academy of Sciences (IAP RAS) develops multi-purpose radiometry complex for constant atmospheric monitoring. For now, it measures temperature profiles from ground to 55km, tropospheric water vapor and ozone. It consists of several radiometers with spectral bands ranging from 20 to 112 GHz. In 2015 two radiometers were added in order to measure thermal structure at surface level and troposphere: scanning device operating in 55-59GHz, and device at 50-55GHz. The change led to modifying the retrieval software. The work presents the description of the radiometry complex and corresponding retrieval software. The main part is devoted to new radiometers and enhancements in retrieval procedure. The retrieval algorithms are described: for each device separately and for the whole temperature retrieval part of the complex. The use of the single procedure for the group of radiometers helps to merge the profile with each other correctly. The main issue of the single procedure (numerical complexity aside) is dealing with the possible difference in calibration of the devices. Error analysis of the procedures is conducted. The characteristics of the complex and the retrieval algorithms are presented. The capabilities of the algorithms are shown on simulated and real data; the last one was

  10. Constraining Aerosol Optical Models Using Ground-Based, Collocated Particle Size and Mass Measurements in Variable Air Mass Regimes During the 7-SEAS/Dongsha Experiment

    NASA Technical Reports Server (NTRS)

    Bell, Shaun W.; Hansell, Richard A.; Chow, Judith C.; Tsay, Si-Chee; Wang, Sheng-Hsiang; Ji, Qiang; Li, Can; Watson, John G.; Khlystov, Andrey

    2012-01-01

    During the spring of 2010, NASA Goddard's COMMIT ground-based mobile laboratory was stationed on Dongsha Island off the southwest coast of Taiwan, in preparation for the upcoming 2012 7-SEAS field campaign. The measurement period offered a unique opportunity for conducting detailed investigations of the optical properties of aerosols associated with different air mass regimes including background maritime and those contaminated by anthropogenic air pollution and mineral dust. What appears to be the first time for this region, a shortwave optical closure experiment for both scattering and absorption was attempted over a 12-day period during which aerosols exhibited the most change. Constraints to the optical model included combined SMPS and APS number concentration data for a continuum of fine and coarse-mode particle sizes up to PM2.5. We also take advantage of an IMPROVE chemical sampler to help constrain aerosol composition and mass partitioning of key elemental species including sea-salt, particulate organic matter, soil, non sea-salt sulphate, nitrate, and elemental carbon. Our results demonstrate that the observed aerosol scattering and absorption for these diverse air masses are reasonably captured by the model, where peak aerosol events and transitions between key aerosols types are evident. Signatures of heavy polluted aerosol composed mostly of ammonium and non sea-salt sulphate mixed with some dust with transitions to background sea-salt conditions are apparent in the absorption data, which is particularly reassuring owing to the large variability in the imaginary component of the refractive indices. Extinctive features at significantly smaller time scales than the one-day sample period of IMPROVE are more difficult to reproduce, as this requires further knowledge concerning the source apportionment of major chemical components in the model. Consistency between the measured and modeled optical parameters serves as an important link for advancing remote

  11. Location and mapping of hydrologic regimes and thermal waters in Hawai'i: the use of electrical geophysical techniques

    USGS Publications Warehouse

    Kauahikaua, Jim

    1990-01-01

    Useful information on several different hydrologic regimes can be obtained using a combination of electrical geophysical surveys. Fresh-water lenses and laterally-confined aquifers can be located and mapped. However, more studies are required to evaluate the utility of geophysical methods for assessing perched aquifers.

  12. Ground truth measurements plan for the Multispectral Thermal Imager (MTI) satellite

    SciTech Connect

    Garrett, A.J.

    2000-01-03

    Sandia National Laboratories (SNL), Los Alamos National Laboratory (LANL), and the Savannah River Technology Center (SRTC) have developed a diverse group of algorithms for processing and analyzing the data that will be collected by the Multispectral Thermal Imager (MTI) after launch late in 1999. Each of these algorithms must be verified by comparison to independent surface and atmospheric measurements. SRTC has selected 13 sites in the continental U.S. for ground truth data collections. These sites include a high altitude cold water target (Crater Lake), cooling lakes and towers in the warm, humid southeastern US, Department of Energy (DOE) climate research sites, the NASA Stennis satellite Validation and Verification (V and V) target array, waste sites at the Savannah River Site, mining sites in the Four Corners area and dry lake beds in the southwestern US. SRTC has established mutually beneficial relationships with the organizations that manage these sites to make use of their operating and research data and to install additional instrumentation needed for MTI algorithm V and V.

  13. Ground Testing a Nuclear Thermal Rocket: Design of a sub-scale demonstration experiment

    SciTech Connect

    David Bedsun; Debra Lee; Margaret Townsend; Clay A. Cooper; Jennifer Chapman; Ronald Samborsky; Mel Bulman; Daniel Brasuell; Stanley K. Borowski

    2012-07-01

    In 2008, the NASA Mars Architecture Team found that the Nuclear Thermal Rocket (NTR) was the preferred propulsion system out of all the combinations of chemical propulsion, solar electric, nuclear electric, aerobrake, and NTR studied. Recently, the National Research Council committee reviewing the NASA Technology Roadmaps recommended the NTR as one of the top 16 technologies that should be pursued by NASA. One of the main issues with developing a NTR for future missions is the ability to economically test the full system on the ground. In the late 1990s, the Sub-surface Active Filtering of Exhaust (SAFE) concept was first proposed by Howe as a method to test NTRs at full power and full duration. The concept relied on firing the NTR into one of the test holes at the Nevada Test Site which had been constructed to test nuclear weapons. In 2011, the cost of testing a NTR and the cost of performing a proof of concept experiment were evaluated.

  14. Observations and Modelling of Hillslope Throughflow Temperature and Its Influence on Headwater Stream Thermal Regimes in the Rain-on-Snow Zone

    NASA Astrophysics Data System (ADS)

    Leach, J. A.; Moore, R. D.

    2014-12-01

    Stream temperature controls a variety of biological, chemical and physical in-stream processes. A growing body of research has highlighted the importance of advection associated with surface water and groundwater interactions on stream thermal regimes, and considerable effort has focused on the thermal role of hyporheic exchange and groundwater discharge. However, few studies have focused on advection associated with hillslope throughflow inputs. Current catchment-scale coupled hydrology and stream temperature models (DHSVM, SWAT, HSPF, CEQUEAU, MIKE SHE) use a variety of approaches to estimate throughflow temperatures, but none of these approaches has been evaluated against field measurements of throughflow temperature. We monitored throughflow temperature at fifty locations along a headwater stream located in the rain-on-snow zone of the Pacific Northwest. Current approaches to estimate throughflow temperature were evaluated against field observations and were found to under- or over-predict throughflow temperatures by up to 8 °C, or not be able to represent the influence of transient snow cover. Therefore, we developed a conceptual-parametric hydrology and stream temperature model that simulates hillslope throughflow temperatures. The model successfully predicts throughflow temperatures and highlights the dominant role of throughflow advection and the influence of snow cover on stream thermal regimes during high flow periods and rain-on-snow events.

  15. Hydrous pyrolysis/oxidation: in-ground thermal destruction of organic contaminants

    SciTech Connect

    Knauss, K. G.; Aines, R.D.; Dibley, M.J.; Leif, R.N.; Mew, D.A.

    1997-03-11

    Experimental work with organic solvents at Lawrence Livermore National Laboratory has suggested that in situ thermal oxidation of these compounds via hydrous pyrolysis forms the basis for a whole new remediation method, called hydrous pyrolysis oxidation. Preliminary results of hydrothermal oxidation using both dissolved 0{sub 2} gas and mineral oxidants present naturally in soils (e.g., MnO{sub 2}) demonstrate that TCE, TCA, and even PCE can be rapidly and completely degraded to benign products at moderate conditions, easily achieved in thermal remediation. Polycyclic aromatic hydrocarbons (PAHS) have an even larger thermodynamic driving force favoring oxidation, and they are also amenable to in situ destruction. Today, the principal treatment methods for chlorinated solvent- and PAH-contaminated soil are to remove it to landfills, or incinerate it on site. The most effective method for treating ground water, Dynamic Underground Stripping (Newmark et al., 1995), still involves removing the contaminant for destruction elsewhere. Hydrous pyrolysis/oxidation would eliminate the need for long-term use of expensive treatment facilities by converting all remaining contaminant to benign products (e.g., carbon dioxide, water, and chloride ion). The technique is expected to be applicable to dense non-aqueous phase liquids (DNAPLS) and dissolved organic components. Soil and ground water would be polished without bringing them to the surface. This would dramatically decrease the cost of final site closure efforts. Large-scale cleanup using hydrous pyrolysis/oxidation may cost less than $10/yd. The end product of hydrous pyrolysis/oxidation is expected to be a clean site. The delivery concept for hydrous pyrolysis/oxidation utilizes the established experience in heating large volumes of ground developed in the Dynamic Underground Stripping Demonstration (Newmark et al., 1995). Steam and possibly oxygen are injected together, building a heated, oxygenated zone in the

  16. Thermal-infrared imager TIR on Hayabusa2: Result of ground calibration

    NASA Astrophysics Data System (ADS)

    Okada, T.; Fukuhara, T.; Tanaka, S.; Taguchi, M.; Arai, T.; Imamura, T.; Senshu, H.; Sekiguchi, T.; Ogawa, Y.; Demura, H.; Sakatani, N.; Horikawa, Y.; Helbert, J.; Mueller, T.; Hagermann, A.; H. TIR-Team

    2014-07-01

    -physical properties of boulders or materials inside huge crates are important targets to observe. Evident thermal measurements are conducted to compare them with thermal model for ground observation, and to investigate Yarkovsky or YORP effects. If the orbiting satellites or dust clouds exist at the surroundings, asteroid mass or dust properties will be determined. Cooperative observation with radiometer on MASCOT is also important to determine the thermo-physical properties precisely. We conducted radiometric and geometric calibration for TIR. We use the cavity black-body and oil-bath based black-body plates for calibration at higher temperature from 25 to 150 °C. We also use the black-body plate inside the vacuum chamber for lower temperature from -40 to +50 °C. Both of appratuses share the temperature region from 25 to 50 °C. For geometrical correction, collimator is used measure the square-shaped target. For cross-calibration, the same targets are used for other instruments: 30 cm diameter serpentine target plate with heater is shared with MARA radiometer on MASCOT, and the same meteorite samples (Murchison CM2 meteorites, Murray CM2 meteorites) are shared with NIRS3 spectrometer and ONC camera. The landscape and the walls of test sites were imaged for demonstration. TIR is able to measure the surface temperature from -40 to 150 °C at the central region of images (a little wider range but less resolution at non-central region). The absolute temperature is less than 2 °C, and the resolution (NETD) is less than 0.3 °C for most of conditions. TIR is well calibrated thermal-infrared imager to take thermal images of asteroid and investigate its thermo-physical properties. This type of instruments will be used in other future missions for scientific and operational purposes.

  17. The operating regimes and basic control principles of SNPS Topaz''. [Cs

    SciTech Connect

    Makarov, A.N.; Volberg, M.S.; Grayznov, G.M.; Zhabotinsky, E.E.; Serbin, V.I. )

    1991-01-05

    The basic operating regimes of space nuclear power system (SNPS) Topaz'' are considered. These regimes include: prelaunch preparation and launch into working orbit, SNPS start-up to obtain desired electric power, nominal regime, SNPS shutdown. The main requirements for SNPS at different regimes are given, and the control algorithms providing these requirements are described. The control algorithms were chosen on the basis of theoretical studies and ground power tests of the SNPS prototypes. Topaz'' successful ground and flight tests allow to conclude that for SNPS of this type control algorithm providing required thermal state of cesium vapor supply system and excluding any possibility of discharge processes in current conducting elements is the most expedient at the start-up regime. At the nominal regime required electric power should be provided by maintenance of reactor current and fast-acting voltage regulator utilization. The limitation of the outlet coolant temperature should be foreseen also.

  18. Long-term monitoring of bedrock permafrost within the MOREXPERT project - A scale-dependent approach for the investigation of ground thermal conditions in a high alpine environment, Kitzsteinhorn, Austria

    NASA Astrophysics Data System (ADS)

    Hartmeyer, I.; Keuschnig, M.; Schrott, L.

    2012-04-01

    '). Two permanent ERT (Electrical Resistivity Tomography) profiles have been installed on north-facing slopes for automated recording of subsurface electrical resistivity conditions. ERT surveys do not permit direct temperature measurements and therefore do not deliver direct permafrost evidence. Yet laboratory calibration of a temperature-resistivity-relationship allows the indirect inference of thermal information from electrical resistivity values obtained in the field. At the 'slope scale' depth of investigation is reduced by half (15m) compared to the borehole scale (30m), therefore eliminating the possibility to observe long-time shifts of permafrost temperatures in great depths. However, as information on thermal conditions is collected along a two-dimensional profile line, a 'horizontal dimension' is added at this scale level. At the 'slope scale' it is therefore possible to take into account the horizontal variability of active layer dynamics, freeze-thaw cycles and ground surface temperature patterns. The entire summit pyramid of the Kitzsteinhorn (300 meters in height, 3.5ha) represents the largest investigation scale ('mountain scale'). At this scale level near-surface rock temperatures are recorded by dozens of miniature temperature loggers in various depths (up to 80cm). In comparison to the 'borehole scale' and the 'slope scale' investigation depth is further reduced implicating that information on permafrost dynamics have to be inferred from ground surface temperature patterns. At the 'mountain scale' focus shifts to the recognition of the horizontal heterogeneity of ground surface temperatures and freeze-thaw cycles over comparatively large areas. Thermal information is collected for different altitudes, aspects and slope inclinations yielding a quasi-spatial image of the Kitzsteinhorn's ground thermal regime.

  19. Thermal Contraction Crack Polygon Classification and Distribution: Morphological Variations in Northern Hemisphere Patterned Ground

    NASA Astrophysics Data System (ADS)

    Levy, J.; Head, J.; Marchant, D.

    2008-09-01

    Polygonally patterned ground has been identified on Mars since the Viking era [1], and has long been interpreted as a signal of the presence of subsurface ice deposits [2-4]. The origin of ice in the shallow martian subsurface, whether by cyclical vapour diffusion or primary deposition, remains an area of active inquiry [5- 9]. Recent modelling suggests that high-latitude terrains on Mars may support buried ice sheets and glaciers, produced by direct atmospheric deposition within the past 5 My [5], overlain by a sublimation lag deposit ranging in thickness from 10s to 100s of cm [8]. These results are consistent with coarse-resolution (100s of km per pixel) neutron-spectrometer results correlating highlatitude patterned ground with subsurface water [4, 10, 11], as well as a suite of geomorphological observations linking young terrains to recently deposited, ice-rich units [5-7]. Polygon classification in terrestrial polar environments is based on morphology, structure, and origin processes. On Earth, thermal contraction crack polygons can be divided into three types: ice-wedge, sand-wedge, and sublimation polygons; each of which forms under a unique set of climate and substrate-composition conditions [12-14]. Although the thermal contraction cracking process under martian conditions is well understood [15], classification systems for polygonally patterned ground on Mars have until now relied primarily on imaging data at resolutions comparable to the scale of the polygons of interest [3]. We build on the identification of sublimation polygons in the NASA Phoenix landing area [16], and preliminary classification of polygons into morphological species (groups distinguishable by characteristic surface morphologies) [17] across the northern hemisphere of Mars. We present an integrated assessment of martian polygon morphological variation as a function of latitude, and suggest links between polygon morphology, origin timing, and global climate conditions. This analysis

  20. Theoretical regime diagrams for thermally driven flows in a beta-plane channel in the presence of variable gravity

    NASA Technical Reports Server (NTRS)

    Geisler, J. E.; Fowlis, W. W.

    1980-01-01

    The effect of a power law gravity field on baroclinic instability is examined, with a focus on the case of inverse fifth power gravity, since this is the power law produced when terrestrial gravity is simulated in spherical geometry by a dielectric force. Growth rates are obtained of unstable normal modes as a function of parameters of the problem by solving a second order differential equation numerically. It is concluded that over the range of parameter space explored, there is no significant change in the character of theoretical regime diagrams if the vertically averaged gravity is used as parameter.

  1. Heating-frequency-dependent thermal conductivity: An analytical solution from diffusive to ballistic regime and its relevance to phonon scattering measurements

    NASA Astrophysics Data System (ADS)

    Yang, Fan; Dames, Chris

    2015-04-01

    The heating-frequency dependence of the apparent thermal conductivity in a semi-infinite body with periodic planar surface heating is explained by an analytical solution to the Boltzmann transport equation. This solution is obtained using a two-flux model and gray mean free time approximation and verified numerically with a lattice Boltzmann method and numerical results from the literature. Extending the gray solution to the nongray regime leads to an integral transform and accumulation-function representation of the phonon scattering spectrum, where the natural variable is mean free time rather than mean free path, as often used in previous work. The derivation leads to an approximate cutoff conduction similar in spirit to that of Koh and Cahill [Phys. Rev. B 76, 075207 (2007), 10.1103/PhysRevB.76.075207] except that the most appropriate criterion involves the heater frequency rather than thermal diffusion length. The nongray calculations are consistent with Koh and Cahill's experimental observation that the apparent thermal conductivity shows a stronger heater-frequency dependence in a SiGe alloy than in natural Si. Finally these results are demonstrated using a virtual experiment, which fits the phase lag between surface temperature and heat flux to obtain the apparent thermal conductivity and accumulation function.

  2. Review of biomaterial thermal property measurements in the cryogenic regime and their use for prediction of equilibrium and non-equilibrium freezing applications in cryobiology.

    PubMed

    Choi, Jeunghwan; Bischof, John C

    2010-02-01

    It is well accepted in cryobiology that the temperature history and cooling rates experienced in biomaterials during freezing procedures correlate strongly with biological outcome. Therefore, heat transfer measurement and prediction in the cryogenic regime is central to the field. Although direct measurement of temperature history (i.e. heat transfer) can be performed, accuracy is usually achieved only for local measurements within a given system and cannot be readily generalized to another system without the aid of predictive models. The accuracy of these models rely upon thermal properties which are known to be highly dependent on temperature, and in the case of significant cryoprotectant loading, also on crystallized fraction. In this work, we review the available thermal properties of biomaterials in the cryogenic regime. The review shows a lack of properties for many biomaterials in the subzero temperature domain, and especially for systems with cryoprotective agents. Unfortunately, use of values from the limited data available (usually only down to -40 degrees C) lead to an underestimation of thermal property change (i.e. conductivity rise and specific heat drop due to ice crystallization) with lower temperatures. Conversely, use of surrogate values based solely on ice thermal properties lead to an overestimation of thermal property change for most biomaterials. Additionally, recent work extending the range of available thermal properties to -150 degrees C has shown that the thermal conductivity will drop in both PBS and tissue (liver) due to amorphous/glassy phases (versus crystalline) of biomaterials with the addition of cryoprotective additives such as glycerol. Thus, we investigated the implications of using approximated or constant property values versus measured temperature-dependent values for predicting temperature history during freezing in PBS (phosphate-buffered saline) and porcine liver with and without cryoprotectants (glycerol). Using measured

  3. Controls on the Flow Regime and Thermal Structure of the Subduction Zone Mantle Wedge: A Systematic 2-D and 3-D Investigation

    NASA Astrophysics Data System (ADS)

    Le Voci, Giuseppe; Davies, Rhodri; Goes, Saskia; Kramer, Stephan; Wilson, Cian

    2014-05-01

    Arc volcanism at subduction zones is likely regulated by the mantle wedge's flow regime and thermal structure and, hence, numerous studies have attempted to quantify the principal controls on mantle wedge conditions. Here, we build on these previous studies by undertaking the first systematic 2-D and 3-D numerical investigation, across a wide parameter-space, into how hydration and thermal buoyancy influence the wedge's flow regime and associated thermal structure, above a kinematically driven subducting plate. We find that small-scale convection (SSC), resulting from Rayleigh-Taylor instabilities, or drips, off the base of the overriding lithosphere, is a typical occurrence, if: (i) viscosities are < 5×1018 Pa s; and (ii) hydrous weakening of wedge rheology extends at least 100-150 km from the trench. In 2-D models, instabilities generally take the form of 'drips'. Although along-strike averages of wedge velocities and temperature in 3-D structure are consistent with those in 2-D, fluctuations are larger in 3-D. Furthermore, in 3-D, two separate, but interacting, longitudinal Richter roll systems form (with their axes aligned perpendicular to the trench), the first below the arc region and the second below the back-arc region. These instabilities result in transient and spatial temperature fluctuations of 100-150K, which are sufficient to influence melting, the stability of hydrous minerals and the dehydration of crustal material. Furthermore, they are efficient at eroding the overriding lithosphere, particularly in 3-D and, thus, provide a means to explain observations of high heat flow and thin back-arc lithosphere at many subduction zones, if back-arc mantle is hydrated.

  4. Thermal control for the ground simulation of a space IR sensor system

    NASA Technical Reports Server (NTRS)

    Lee, E.; Warren, A.; Gasser, G.; Tierney, M.

    1990-01-01

    Active and passive thermal controls for simulations of a space IR sensor system operating in cryogenic temperatures were designed, built, and tested from a component level to a system level. The test results from component tests and integrated system tests have compared very well with theoretical predictions, and thus verify component and integrated thermal math models. These verified models can be modified for use to predict flight systems thermal performance. Thermal vacuum simulations and demonstrations of a space IR system consisted of a target and background scene generator, telescope mirrors supported by a graphite-epoxy metering structure, and an IR sensor. These components are required to operate at cryogenic temperature levels. Each component has its unique thermal control needs. Descriptions are presented of thermal control systems for the test article from component design level to integrated system level along with discussions of component and integrated demonstration tests, and correlation of test data with thermal finite difference models.

  5. Ground-based thermal and multispectral imaging of limited irrigation crops

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ground-based methods of remote sensing can be used as ground-truth for satellite-based remote sensing, and in some cases may be a more affordable means of obtaining such data. Plant canopy temperature has been used to indicate and quantify plant water stress. A field research study was conducted in ...

  6. Ground-Based Remote Sensing of Water-Stressed Crops: Thermal and Multispectral Imaging

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ground-based methods of remote sensing can be used as ground-truthing for satellite-based remote sensing, and in some cases may be a more affordable means of obtaining such data. Plant canopy temperature has been used to indicate and quantify plant water stress. A field research study was conducted ...

  7. Thermal energy supply optimization for Edgewood Area, US Army Aberdeen Proving Ground: Energy supply alternatives. Final report

    SciTech Connect

    McCammon, T.L.; Dilks, C.L.; Savoie, M.J.

    1995-09-01

    Relatively poor performance at the aging central heating plants (OH Ps) and planned changes in steam demand at Aberdeen Proving Ground (APG) Edgewood Area, Aberdeen, MD warranted an investigation of alternatives for providing thermal energy to the installation. This study: (1) evaluated the condition of the APG CHPs and heat distribution system, (2) identified thermal energy supply problems and cost-effective technologies to maintain APG`s capability to produce and distribute the needed thermal energy, and (3) recommended renovation and modernization projects for the system. Heating loads were analyzed using computer simulations, and life cycle costs were developed for each alternative. Recommended alternatives included upgrading the existing system, installing new boilers, consolidating the central heating plants, and introducing the use of absorption chilling.

  8. Sensitivity in the Correction of Long-Range Ground-Based Thermal Data.

    NASA Astrophysics Data System (ADS)

    Hancock, Anson; James, Mike; Ganci, Gaetana; Harris, Andrew

    2016-04-01

    Ground-based thermal remote sensing is a valuable tool for the study and monitoring of volcanoes and their hazards. However, permanent monitoring installations often require the camera to be positioned at relatively long ranges from the target (i.e. >1000 m). These types of long-range deployments have been seldom analysed quantitatively due primarily to factors such as atmospheric attenuation and across-image variations in the target path-length resulting in substantial uncertainty in the derived surface temperatures. Here we examine the sensitivity of measurements at three different apparent temperatures (400, 500 and 600 K) to uncertainty in the atmospheric conditions and type of path for the INGV-Catania (Etna, Sicily) permanently installed thermal camera. The camera is located at Mount Cagliato at an elevation of 1154 m asl and looks to the summit area at ˜3000 m asl, over a distance of ˜8.5 km. Analysis was carried out using MODTRAN to calculate atmospheric transmittance and upwelling radiance values for the different scenarios. We then calculated corrected surface temperatures by applying an atmospheric correction using two different temperature-to-radiance methods: a top-hat wavelength integrated based method supplied by FLIR Systems in their ThermaCam Researcher software and a mid-wavelength value method using the Planck equation. Results indicate that calculated surface temperatures between the two methods differ by as much as 382.5 K over a path-length of 8.5 km. Over path lengths between 1 and 8.5 km, changing the atmospheric temperature to 288.15 (15 oC), 293.15 (20 oC) and 298.15 K (25 oC) resulted in increases in calculated surface temperatures of 1.7-72.4 K using the FLIR top-hat method and 1.4-205.5 K using the mid-wavelength method. For relative humidities of 40, 50 and 60 %, increases in calculated surface temperatures of 1.0-58.7 K and 1.0-148.9 K using the FLIR top-hat and mid-wavelength methods, respectively. We also found that calculated

  9. Prediction of In-Space Durability of Protected Polymers Based on Ground Laboratory Thermal Energy Atomic Oxygen

    NASA Technical Reports Server (NTRS)

    Banks, Bruce A.; deGroh, Kim K.; Rutledge, Sharon; DiFilippo, Frank J.

    1996-01-01

    The probability of atomic oxygen reacting with polymeric materials is orders of magnitude lower at thermal energies (greater than O.1 eV) than at orbital impact energies (4.5 eV). As a result, absolute atomic oxygen fluxes at thermal energies must be orders of magnitude higher than orbital energy fluxes, to produce the same effective fluxes (or same oxidation rates) for polymers. These differences can cause highly pessimistic durability predictions for protected polymers and polymers which develop protective metal oxide surfaces as a result of oxidation if one does not make suitable calibrations. A comparison was conducted of undercut cavities below defect sites in protected polyimide Kapton samples flown on the Long Duration Exposure Facility (LDEF) with similar samples exposed in thermal energy oxygen plasma. The results of this comparison were used to quantify predicted material loss in space based on material loss in ground laboratory thermal energy plasma testing. A microindent hardness comparison of surface oxidation of a silicone flown on the Environmental Oxygen Interaction with Materials-III (EOIM-III) experiment with samples exposed in thermal energy plasmas was similarly used to calibrate the rate of oxidation of silicone in space relative to samples in thermal energy plasmas exposed to polyimide Kapton effective fluences.

  10. Analysis of Influence of Heat Insulation on the Thermal Regime of Storage Tanks with Liquefied Natural Gas

    NASA Astrophysics Data System (ADS)

    Maksimov, Vyacheslav I.; Nagornova, Tatiana A.; Glazyrin, Viktor P.; Shestakov, Igor A.

    2016-02-01

    Is numerically investigated the process of convective heat transfer in the reservoirs of liquefied natural gas (LNG). The regimes of natural convection in a closed rectangular region with different intensity of heat exchange at the external borders are investigated. Is solved the time-dependent system of energy and Navier-Stokes equations in the dimensionless variables "vorticity - the stream function". Are obtained distributions of the hydrodynamic parameters and temperatures, that characterize basic regularities of the processes. The special features of the formation of circulation flows are isolated and the analysis of the temperature distribution in the solution region is carried out. Is shown the influence of geometric characteristics and intensity of heat exchange on the outer boundaries of reservoir on the temperature field in the LNG storage.

  11. Thermal performance of soils and backfills in horizontal ground coupled heat pump system applications. Final report

    SciTech Connect

    1998-04-01

    The goal of this research was to address the appropriateness of different soils, in an unsaturated state, for placement adjacent to the buried heat exchanger for GSHP systems. Soils for the study were selected based on an analysis of common soil parent materials that exist in the US in conjunction with the current EPRI soil thermal classification system. Six soils were chosen (Cecil (clay), Fordville (sand), Kranzburg (loam), Moody (silt), Sharpsburg (silt) and Vienna (sandy loam)) which provided at least one soil in each of the EPRI classifications. Initial laboratory studies were concentrated on determination of basic physical, water holding and thermal properties of each soil. Each soil was evaluated for ability to sustain thermal contact conductance under thermal loading, and comparison of the results allowed the soils to be ranked, best to worst. Additional laboratory studies were performed on each soil to rate the long-term thermal performance of each relative to potential for drying adjacent to the heat exchanger along with reduction in heat transfer rate due to soil drying. Tests were conducted over a range of initial water contents and densities that would be common for each soil. Results were used to verify a theoretical analysis of the thermal stability of each soil, based on texture, and to rank each soil according to thermal performance under extended thermal load. Results of the thermal conductivity tests, the thermal contact conductance tests and the thermal performance tests were utilized to propose a thermal performance index (TPI) for soils based on texture. The final soil ranking were then expressed relative to the EPRI soil thermal classification system which identified clay as best, followed by loam, sandy loam, silt, and sand.

  12. Combining Bioenergetic Responses of Fish to Thermal Regimes and Productivity in Reservoirs: Implications for Conservation and Re-Introduction of Anadromous Salmonids

    NASA Astrophysics Data System (ADS)

    Beauchamp, D.

    2014-12-01

    Temperature, food availability, and predation risk form vertical gradients determining growth and survival for fish in lakes and reservoirs. These gradients change on inter-annual, seasonal, and diel temporal scales and are strongly influenced by climatic variability, conflicting water demands and management. Temperatures associated with optimal growth and energy loss vary both among life stages and species of fish, but the quantity and quality of available food resources can significantly alter these thermal responses. Greater understanding of how water management affects the timing, magnitude, and duration of thermal stratification, and how key species and their supporting aquatic resources respond can improve strategies for development and operation of water storage facilities within the context of localized environmental and ecological constraints. An emerging trend for coldwater reservoirs in the Pacific Northwest has been to re-introduce anadromous salmon above historically impassable dams. Thermal regimes and the existing ecological communities in the reservoirs and tributary habitats above these dams will determine the seasonal importance of lotic and lentic habitats for rearing or migration corridors. The feasibility of reservoir rearing and migration can be evaluated by combining mass- and species-specific thermal growth response curves with temporal dynamics in the vertical and longitudinal thermal structure of reservoirs and associated distribution of food resources (primarily zooplankton). The value of reservoirs as rearing habitats or migration corridors could be compared with coincident tributary conditions to predict the likely temporal-spatial distribution of optimal conditions for growth and survival of different species or life stages of salmonids within the watershed and how these conditions might change under different climatic or water management scenarios.

  13. Impacts of projected mid-century temperatures on thermal regimes for select specialty and fieldcrops common to the southwestern U.S.

    NASA Astrophysics Data System (ADS)

    Elias, E.; Lopez-Brody, N.; Dialesandro, J.; Steele, C. M.; Rango, A.

    2015-12-01

    The impacts of projected temperature increases in agricultural ecosystems are complex, varyingby region, cropping system, crop growth stage and humidity. We analyze the impacts of mid-century temperature increases on crops grown in five southwestern states: Arizona, California,New Mexico, Nevada and Utah. Here we present a spatial impact assessment of commonsouthwestern specialty (grapes, almonds and tomatoes) and field (alfalfa, cotton and corn)crops. This analysis includes three main components: development of empirical temperaturethresholds for each crop, classification of predicted future climate conditions according to thesethresholds, and mapping the probable impacts of these climatic changes on each crop. We use30m spatial resolution 2012 crop distribution and seasonal minimum and maximumtemperature normals (1970 to 2000) to define the current thermal envelopes for each crop.These represent the temperature range for each season where 95% of each crop is presentlygrown. Seasonal period change analysis of mid-century temperatures changes downscaled from20 CMIP5 models (RCP8.5) estimate future temperatures. Change detection maps representareas predicted to become more or less suitable, or remain unchanged. Based upon mid-centurytemperature changes, total regional suitable area declined for all crops except cotton, whichincreased by 20%. For each crop there are locations which change to and from optimal thermalenvelope conditions. More than 80% of the acres currently growing tomatoes and almonds willshift outside the present 95% thermal range. Fewer acres currently growing alfalfa (14%) andcotton (20%) will shift outside the present 95% thermal range by midcentury. Crops outsidepresent thermal envelopes by midcentury may adapt, possibly aided by adaptation technologiessuch as misters or shade structures, to the new temperature regime or growers may elect togrow alternate crops better suited to future thermal envelopes.

  14. Simulating the thermal operating conditions in the thermal wells of ground-source heat-pump heat supply systems. Part I: Porous moisture freezing processes in soil

    NASA Astrophysics Data System (ADS)

    Vasilyev, G. P.; Peskov, N. V.; Lichman, V. A.; Gornov, V. F.; Kolesova, M. V.

    2015-08-01

    The mathematical models laid down in the new blocks of the INSOLAR.GSHP.12 software system simulating unsteady operating conditions of ground-source heat-pump (GSHP) heat supply systems are presented. The new model blocks take into account the effect the freezing of porous moisture in soil has on the GSHP system performance efficiency. Illustration is given to the need of taking into account the porous moisture freezing/thawing processes in soil, and the results from investigations devoted to the opening possibilities of constructing adaptive GSHP systems with controlled intensity of heat transfer in the soil-thermal well system are presented. The development of software simulating the porous moisture phase state variation processes in soil was preceded by development of mathematical equations representing the thermal conditions of soil body involving porous moisture freezing/thawing processes. A description of these equations is also given in the article. In constructing the mathematical model, the notion "effective thermal conductivity" of soil was introduced for taking into account the latent heat of phase transition that releases during the freezing of moisture. The above-mentioned effective thermal conductivity of soil involves two components: the soil thermal conductivity coefficient itself and an additional term modifying the thermal conductivity value for taking into account the influence of phase transition. For quantitatively evaluating the soil effective thermal conductivity component that takes into account the influence of phase transition, the soil freezing zone radius around the thermal well was determined. The obtained analytic solutions have been implemented in the form of computer program blocks, after which a "numerical experiment" was carried out for estimating the effect the porous moisture freezing/thawing processes have on the soil thermal conditions. It was demonstrated during that experiment that the soil thermal conductivities determined

  15. Environmental effects of solar-thermal-power systems. Systematic status of the Mojave ground squirrel, Spermophilus mohavensis (subgenus Xerospermophilus)

    SciTech Connect

    Hafner, D.J.; Yates, T.L.

    1982-06-01

    The Mojave ground squirrel, Spermophilus mohavensis, is listed as a rare species by the California Fish and Game Commission. Its well-being has emerged as an environmental concern associated with deployment of solar thermal power systems in western parts of the Mojave Desert. The more common round-tailed ground squirrel, Spermophilus tereticaudus, also occurs in the Mojave Desert, and this species closely resembles S. mohavensis. In some areas it may be extremely difficult, on the basis of external characters, to identify the species present. The systematic status of the sibling species Spermophilus mohavensis and S. tereticaudus (subgenus Xerosphermophilus) was investigated throughout the range of the subgenus, based on allozymic and chromosomal data. Hybridization of the two species was detected only at a single disturbed site, while allelic introgression was confined to an estimated 60 km reach of the Mojave River wash. In the absence of an analysis of a zone of natural sympatry, the two taxa are retained as full biological species. The population of ground squirrels just east of Solar One, the 10 MWe pilot solar thermal power plant, is composed of individuals referable to S. tereticaudus based on both allozymic and chromosomal criteria.

  16. Three Temperature Regimes in Superconducting Photon Detectors: Quantum, Thermal and Multiple Phase-Slips as Generators of Dark Counts

    PubMed Central

    Murphy, Andrew; Semenov, Alexander; Korneev, Alexander; Korneeva, Yulia; Gol’tsman, Gregory; Bezryadin, Alexey

    2015-01-01

    We perform measurements of the switching current distributions of three w ≈ 120 nm wide, 4 nm thick NbN superconducting strips which are used for single-photon detectors. These strips are much wider than the diameter of the vortex cores, so they are classified as quasi-two-dimensional (quasi-2D). We discover evidence of macroscopic quantum tunneling by observing the saturation of the standard deviation of the switching distributions at temperatures around 2 K. We analyze our results using the Kurkijärvi-Garg model and find that the escape temperature also saturates at low temperatures, confirming that at sufficiently low temperatures, macroscopic quantum tunneling is possible in quasi-2D strips and can contribute to dark counts observed in single photon detectors. At the highest temperatures the system enters a multiple phase-slip regime. In this range single phase-slips are unable to produce dark counts and the fluctuations in the switching current are reduced. PMID:25988591

  17. Three temperature regimes in superconducting photon detectors: quantum, thermal and multiple phase-slips as generators of dark counts.

    PubMed

    Murphy, Andrew; Semenov, Alexander; Korneev, Alexander; Korneeva, Yulia; Gol'tsman, Gregory; Bezryadin, Alexey

    2015-01-01

    We perform measurements of the switching current distributions of three w ≈ 120 nm wide, 4 nm thick NbN superconducting strips which are used for single-photon detectors. These strips are much wider than the diameter of the vortex cores, so they are classified as quasi-two-dimensional (quasi-2D). We discover evidence of macroscopic quantum tunneling by observing the saturation of the standard deviation of the switching distributions at temperatures around 2 K. We analyze our results using the Kurkijärvi-Garg model and find that the escape temperature also saturates at low temperatures, confirming that at sufficiently low temperatures, macroscopic quantum tunneling is possible in quasi-2D strips and can contribute to dark counts observed in single photon detectors. At the highest temperatures the system enters a multiple phase-slip regime. In this range single phase-slips are unable to produce dark counts and the fluctuations in the switching current are reduced. PMID:25988591

  18. Impact of climate change on soil thermal and moisture regimes in Serbia: An analysis with data from regional climate simulations under SRES-A1B.

    PubMed

    Mihailović, D T; Drešković, N; Arsenić, I; Ćirić, V; Djurdjević, V; Mimić, G; Pap, I; Balaž, I

    2016-11-15

    We considered temporal and spatial variations to the thermal and moisture regimes of the most common RSGs (Reference Soil Groups) in Serbia under the A1B scenario for the 2021-2050 and 2071-2100 periods, with respect to the 1961-1990 period. We utilized dynamically downscaled global climate simulations from the ECHAM5 model using the coupled regional climate model EBU-POM (Eta Belgrade University-Princeton Ocean Model). We analysed the soil temperature and moisture time series using simple statistics and a Kolmogorov complexity (KC) analysis. The corresponding metrics were calculated for 150 sites. In the future, warmer and drier regimes can be expected for all RSGs in Serbia. The calculated soil temperature and moisture variations include increases in the mean annual soil temperature (up to 3.8°C) and decreases in the mean annual soil moisture (up to 11.3%). Based on the KC values, the soils in Serbia are classified with respect to climate change impacts as (1) less sensitive (Vertisols, Umbrisols and Dystric Cambisols) or (2) more sensitive (Chernozems, Eutric Cambisols and Planosols). PMID:27473773

  19. Structural controls, alteration, permeability and thermal regime of Dixie Valley from new-generation MT/galvanic array profiling

    SciTech Connect

    Philip E. Wannamaker

    2007-11-30

    State-of-the-art MT array measurements in contiguous bipole deployments across the Dixie Valley thermal area have been integrated with regional MT transect data and other evidence to address several basic geothermal goals. These include 1), resolve a fundamental structural ambiguity at the Dixie Valley thermal area (single rangefront fault versus shallower, stepped pediment; 2), delineate fault zones which have experienced fluid flux as indicated by low resistivity; 3), infer ultimate heat and fluid sources for the thermal area; and 4), from a generic technique standpoint, investigate the capability of well-sampled electrical data for resolving subsurface structure. Three dense lines cross the Senator Fumaroles area, the Cottonwood Creek and main producing area, and the low-permeability region through the section 10-15 area, and have stand-alone MT soundings appended at one or both ends for local background control. Regularized 2-D inversion implies that shallow pediment basement rocks extend for a considerable distance (1-2 km) southeastward from the topographic scarp of the Stillwater Range under all three dense profiles, but especially for the Senator Fumaroles line. This result is similar to gravity interpretations in the area, but with the intrinsic depth resolution possible from EM wave propagation. Low resistivity zones flank the interpreted main offsetting fault especially toward the north end of the field which may be due to alteration from geothermal fluid outflow and upflow. The appended MT soundings help to substantiate a deep, subvertical conductor intersecting the base of Dixie Valley from the middle crust, which appears to be a hydrothermal conduit feeding from deep crustal magmatic underplating. This may supply at least part of the high temperature fluids and explain enhanced He-3 levels in those fluids.

  20. Thermal Regime Inferred from Magnetic Anomaly Data in the Crust beneath the Japanese Islands, and its Relationship to Focal Depth

    NASA Astrophysics Data System (ADS)

    Tanaka, A.; Ishikawa, Y.

    2003-12-01

    One of the indicators of lithospheric strength is the focal depth distribution of earthquakes. Temperature has long been regarded as an important variable in determining the seismogenic portion of the lithosphere. The thickness of seismogenic crust layer correlates with surface heat flow in most interplate seismic areas of the world [e.g., Sibson, 1982]. However, heat flow measurements are often widely spaced, requiring an extrapolation of the data to estimate the thermal structure in the crust in some regions. The uncertainties associated with these extrapolations preclude improving on the general correlation between heat flow and depth of seismicity. We used another approach to estimate the thermal structure in the crust. The bottom of the magnetized crust determined from the spectral analysis of residual magnetic anomalies is generally interpreted as the level of the Curie point isotherm. We estimate the bottom of the magnetized crust, Zb, of squares of 2.125o subregions using the magnetic anomaly map of the Japanese Islands [Makino et al., 1992]. At the same region, the thickness of seismogrnic crust is estimated as the depth above which 90 percent of the earthquakes occur, D90, using good quality hypocenters by JMA (Japan Meteorological Agency) data. Zb and D90 range from about 11 to 32 km and 12 km to 28 km, respectively. This suggests that our analysis cannot catch a locally shallow depth. And it is consistent with the expected inverse relation between Zb and the minimum heat flow values [Yamano et al., 1997] within the subregions. The inverse relation between Zb and D90 suggests that this analysis is useful to estimate the regional thermal structure.

  1. Electronic transport regimes through an alkoxythiolated diphenyl-2,2'-bithiophene-based molecular junction diodes: critical assessment of the thermal dependence.

    PubMed

    Pace, Giuseppina; Caranzi, Lorenzo; Bucella, Sadir G; Canesi, Eleonora V; Dell'Erba, Giorgio; Bertarelli, Chiara; Caironi, Mario

    2015-02-01

    The detailed understanding of electronic transport through a single molecule or an ensemble of self-assembled molecules embedded between two metallic leads is still a matter of controversy. Multiple factors influence the charge transport in the molecular junction, with particular attention to be given to the band states of the electrodes, molecular orbital energies, bias potential and importantly molecule-electrode electronic coupling. Moreover it is not trivial to disentangle molecular contributions from other possible conduction pathways directly coupling the opposite electrodes. We here investigate the electronic transport properties of an ensemble molecular junction embedding an alkylthiol derivative of a diphenol substituted bithiophene (DPBT) by means of current vs. voltage and temperature dependent measurements. We explored different junction configurations using: micropores (Au//DPBT//Au and Au//DPBT-polymer conductor//Au) and conductive-atomic force microscopy (c-AFM). In all cases, we found a transition voltage V(T) of ∼0.35 V. The consistent presence of a similar V(T) in all the tested configurations is a strong, but not conclusive, indication of a molecular signature in the charge transport, which we assessed and confirmed by temperature dependent measurements. We found a transition from an incoherent resonant tunneling at low biases and close to room temperature, where transport is thermally activated with an activation energy of ∼85 meV, to a coherent tunneling at voltages higher than V(T). Unlike many other molecular junctions reported in the literature, resonant conditions commonly attributed to a hopping transport regime can be found already at room temperature and very low biases for a molecule only ∼1.5 nm long. This paper is the first report to clearly show temperature activated transport through a short and not fully conjugated molecule. Moreover, we could clearly identify a regime at low temperatures and low bias where the transport

  2. Simulation of characteristics of thermal and hydrologic soil regimes in equilibrium numerical experiments with a climate model of intermediate complexity

    NASA Astrophysics Data System (ADS)

    Arzhanov, M. M.; Demchenko, P. F.; Eliseev, A. V.; Mokhov, I. I.

    2008-10-01

    The IAP RAS CM (Institute of Atmospheric Physics, Russian Academy of Sciences, climate model) has been extended to include a comprehensive scheme of thermal and hydrologic soil processes. In equilibrium numerical experiments with specified preindustrial and current concentrations of atmospheric carbon dioxide, the coupled model successfully reproduces thermal characteristics of soil, including the temperature of its surface, and seasonal thawing and freezing characteristics. On the whole, the model also reproduces soil hydrology, including the winter snow water equivalent and river runoff from large watersheds. Evapotranspiration from the soil surface and soil moisture are simulated somewhat worse. The equilibrium response of the model to a doubling of atmospheric carbon dioxide shows a considerable warming of the soil surface, a reduction in the extent of permanently frozen soils, and the general growth of evaporation from continents. River runoff increases at high latitudes and decreases in the subtropics. The results are in qualitative agreement with observational data for the 20th century and with climate model simulations for the 21st century.

  3. Environmental effects of solar-thermal power systems. Systematic status of the Mojave ground squirrel, Spermophilus mohavensis (subgenus Xerospermophilus)

    SciTech Connect

    Hafner, D.J.; Yates, T.L.

    1982-06-01

    The Mojave ground squirrel, Spermophilus mohavensis, is listed as a rare species by The California Fish and Game Commission. Its well-being has emerged as an environmental concern associated with deployment of solar thermal power systems in western parts of the Motave Desert. The more common round-tailed ground squirrel, Spermophilus tereticaudus, also occurs in the Mojave Desert, and this species closely resembles S. mohavensis. The systematic status of the sibling species was investigated using allozymic and chromosomal data. Karyotypically, the two species differ in diploid number while they share a level of genic similarity reported for other mammalian semispecies. Hybridization was detected only at a single disturbed site, while allelic introgression was confined to an estimated 60 km reach. The two taxa are retained as full biological species.

  4. VALIDATION OF COOKING TIMES AND TEMPERATURES FOR THERMAL INACTIVATION OF YERSINIA PESTIS STRAINS KIM5 AND CDC-A1112 IN GROUND BEEF

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The thermal stability of Yersinia pestis inoculated into retail ground beef (25 per cent fat) and heated in a temperature-controlled water bath or cooked on commercial grills was evaluated. Irradiated ground beef (3-g portions) was inoculated with ca. 6.7 log10 CFU/g of Y. pestis strain KIM5 and hea...

  5. Monoenergetic acceleration of a target foil by circularly polarized laser pulse in RPA regime without thermal heating

    SciTech Connect

    Khudik, V.; Yi, S. A.; Siemon, C.; Shvets, G.

    2012-12-21

    A kinetic model of the monoenergetic acceleration of a target foil irradiated by the circularly polarized laser pulse is developed. The target moves without thermal heating with constant acceleration which is provided by chirping the frequency of the laser pulse and correspondingly increasing its intensity. In the accelerated reference frame, bulk plasma in the target is neutral and its parameters are stationary: cold ions are immobile while nonrelativistic electrons bounce back and forth inside the potential well formed by ponderomotive and electrostatic potentials. It is shown that a positive charge left behind of the moving target in the ion tail and a negative charge in front of the target in the electron sheath form a capacitor whose constant electric field accelerates the ions of the target. The charge separation is maintained by the radiation pressure pushing electrons forward. The scalings of the target thickness and electromagnetic radiation with the electron temperature are found.

  6. The influence of stream thermal regimes and preferential flow paths on hyporheic exchange in a glacial meltwater stream

    NASA Astrophysics Data System (ADS)

    Cozzetto, Karen D.; Bencala, Kenneth E.; Gooseff, Michael N.; McKnight, Diane M.

    2013-09-01

    Given projected increases in stream temperatures attributable to global change, improved understanding of relationships between stream temperatures and hyporheic exchange would be useful. We conducted two conservative tracer injection experiments in a glacial meltwater stream, to evaluate the effects of hyporheic thermal gradients on exchange processes, including preferential flow paths (PFPs). The experiments were conducted on the same day, the first (a stream injection) during a cool, morning period and the second (dual stream and hyporheic injections) during a warm, afternoon period. In the morning, the hyporheic zone was thermally uniform at 4°C, whereas by the afternoon the upper 10 cm had warmed to 6-12°C and exhibited greater temperature heterogeneity. Solute transport modeling showed that hyporheic cross-sectional areas (As) at two downstream sites were two and seven times lower during the warm experiment. Exchange metrics indicated that the hyporheic zone had less influence on downstream solute transport during the warm, afternoon experiment. Calculated hyporheic depths were less than 5 cm, contrasting with tracer detection at 10 and 25 cm depths. The hyporheic tracer arrival at one downstream site was rapid, comparable to the in-stream tracer arrival, providing evidence for PFPs. We thus propose a conceptual view of the hyporheic zone in this reach as being dominated by discrete PFPs weaving through hydraulically isolated areas. One explanation for the simultaneous increase in temperature heterogeneity and As decrease in a warmer hyporheic zone may be a flow path preferentiality feedback mechanism resulting from a combination of temperature-related viscosity decreases and streambed heterogeneity.

  7. Survival, development, and growth of Snake River fall Chinook salmon Embryos, Alevins, and Fry Exposed to Variable Thermal and Dissolved Oxygen Regimes

    SciTech Connect

    Geist, David R.; Abernethy, Cary S.; Hand, Kristine D.; Cullinan, Valerie I.; Chandler, James A.; Groves, Philip

    2006-11-01

    Fall Chinook salmon (Oncorhynchus tshawytscha) initiate spawning in the Hells Canyon reach of the Snake River, Idaho (rkm 240-397), at water temperatures above 16 C. This temperature exceeds the states of Idaho and Oregon water quality standards for salmonid spawning. These standards are consistent with results from studies of embryos exposed to a constant thermal regime, while salmon eggs in the natural environment are rarely exposed to a constant temperature regime. The objective of this study was to assess whether variable temperatures (i.e., declining after spawning) affected embryo survival, development, and growth of Snake River fall Chinook salmon alevins and fry. In 2003, fall Chinook salmon eggs were exposed to initial incubation temperatures ranging from 11-19 C in 2 C increments, and in 2004 eggs were exposed to initial temperatures of 13 C, 15 C, 16 C, 16.5 C, and 17 C. In both years, temperatures were adjusted downward approximately 0.2 C/day to mimic the thermal regime of the Snake River where these fish spawn. At 37-40 days post-fertilization, embryos were moved to a common exposure regime that followed the thermal profile of the Snake River through emergence. Mortality of fall Chinook salmon embryos increased markedly at initial incubation temperatures >17 C in both years. A logistic regression model estimated that a 50% reduction in survival from fertilization to emergence would occur at an initial incubation temperature of {approx}16 C. The laboratory results clearly showed a significant reduction in survival between 15 C and 17 C, which supported the model estimate. Results from 2004 showed a rapid decline in survival occurred between 16.5 C and 17 C, with no significant differences in survival at initial incubation temperatures <16.5 C. There were no significant differences across the range of initial temperature exposures for alevin and fry size at hatch and emergence. Differences in egg mass among females (notably 2003) most likely masked any

  8. Field mapping for heat capacity mapping determinations: Ground support for airborne thermal surveys

    NASA Technical Reports Server (NTRS)

    Lyon, R. J. P.

    1976-01-01

    Thermal models independently derived by Watson, Outcalt, and Rosema were compared using similar input data and found to yield very different results. Each model has a varying degree of sensitivity to any specified parameter. Data collected at Pisgah Crater-Lavic Lake was re-examined to indicate serious discrepancy in results for thermal inertia from Jet Lab Propulsion Laboratory calculations, when made using the same orginal data sets.

  9. Ground Thermal Diffusivity Calculation by Direct Soil Temperature Measurement. Application to very Low Enthalpy Geothermal Energy Systems.

    PubMed

    Andújar Márquez, José Manuel; Martínez Bohórquez, Miguel Ángel; Gómez Melgar, Sergio

    2016-01-01

    This paper presents a methodology and instrumentation system for the indirect measurement of the thermal diffusivity of a soil at a given depth from measuring its temperature at that depth. The development has been carried out considering its application to the design and sizing of very low enthalpy geothermal energy (VLEGE) systems, but it can has many other applications, for example in construction, agriculture or biology. The methodology is simple and inexpensive because it can take advantage of the prescriptive geotechnical drilling prior to the construction of a house or building, to take at the same time temperature measurements that will allow get the actual temperature and ground thermal diffusivity to the depth of interest. The methodology and developed system have been tested and used in the design of a VLEGE facility for a chalet with basement at the outskirts of Huelva (a city in the southwest of Spain). Experimental results validate the proposed approach. PMID:26938534

  10. Soil water content and evaporation determined by thermal parameters obtained from ground-based and remote measurements

    NASA Technical Reports Server (NTRS)

    Reginato, R. J.; Idso, S. B.; Jackson, R. D.; Vedder, J. F.; Blanchard, M. B.; Goettelman, R.

    1976-01-01

    Soil water contents from both smooth and rough bare soil were estimated from remotely sensed surface soil and air temperatures. An inverse relationship between two thermal parameters and gravimetric soil water content was found for Avondale loam when its water content was between air-dry and field capacity. These parameters, daily maximum minus minimum surface soil temperature and daily maximum soil minus air temperature, appear to describe the relationship reasonably well. These two parameters also describe relative soil water evaporation (actual/potential). Surface soil temperatures showed good agreement among three measurement techniques: in situ thermocouples, a ground-based infrared radiation thermometer, and the thermal infrared band of an airborne multispectral scanner.