24 CFR 3280.510 - Heat loss certificate.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 24 Housing and Urban Development 5 2014-04-01 2014-04-01 false Heat loss certificate. 3280.510... URBAN DEVELOPMENT MANUFACTURED HOME CONSTRUCTION AND SAFETY STANDARDS Thermal Protection § 3280.510 Heat... specify the following: (a) Heating zone certification. The design zone at which the manufactured home heat...

24 CFR 3280.510 - Heat loss certificate.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 24 Housing and Urban Development 5 2011-04-01 2011-04-01 false Heat loss certificate. 3280.510... URBAN DEVELOPMENT MANUFACTURED HOME CONSTRUCTION AND SAFETY STANDARDS Thermal Protection § 3280.510 Heat... specify the following: (a) Heating zone certification. The design zone at which the manufactured home heat...

Quantitative trait loci for energy balance traits in an advanced intercross line derived from mice divergently selected for heat loss

PubMed Central

Nielsen, Merlyn K.; Thorn, Stephanie R.; Valdar, William; Pomp, Daniel

2014-01-01

Obesity in human populations, currently a serious health concern, is considered to be the consequence of an energy imbalance in which more energy in calories is consumed than is expended. We used interval mapping techniques to investigate the genetic basis of a number of energy balance traits in an F11 advanced intercross population of mice created from an original intercross of lines selected for increased and decreased heat loss. We uncovered a total of 137 quantitative trait loci (QTLs) for these traits at 41 unique sites on 18 of the 20 chromosomes in the mouse genome, with X-linked QTLs being most prevalent. Two QTLs were found for the selection target of heat loss, one on distal chromosome 1 and another on proximal chromosome 2. The number of QTLs affecting the various traits generally was consistent with previous estimates of heritabilities in the same population, with the most found for two bone mineral traits and the least for feed intake and several body composition traits. QTLs were generally additive in their effects, and some, especially those affecting the body weight traits, were sex-specific. Pleiotropy was extensive within trait groups (body weights, adiposity and organ weight traits, bone traits) and especially between body composition traits adjusted and not adjusted for body weight at sacrifice. Nine QTLs were found for one or more of the adiposity traits, five of which appeared to be unique. The confidence intervals among all QTLs averaged 13.3 Mb, much smaller than usually observed in an F2 cross, and in some cases this allowed us to make reasonable inferences about candidate genes underlying these QTLs. This study combined QTL mapping with genetic parameter analysis in a large segregating population, and has advanced our understanding of the genetic architecture of complex traits related to obesity. PMID:24918027

Impact of Next Generation District Heating Systems on Distribution Network Heat Losses: A Case Study Approach

NASA Astrophysics Data System (ADS)

Li, Yu; Rezgui, Yacine

2018-01-01

District heating (DH) is a promising energy pathway to alleviate environmental negative impacts induced by fossil fuels. Improving the performance of DH systems is one of the major challenges facing its wide adoption. This paper discusses the heat losses of the next generation DH based on the constructed Simulink model. Results show that lower distribution temperature and advanced insulation technology greatly reduce network heat losses. Also, the network heat loss can be further minimized by a reduction of heat demand in buildings.

Heat Loss is Impaired in Older Men on the Day following Prolonged Work in the Heat.

PubMed

Notley, Sean R; Meade, Robert D; DʼSouza, Andrew W; Friesen, Brian J; Kenny, Glen P

2018-04-21

Prolonged work in the heat may exacerbate the rise in core temperature on the next work day, especially in older workers who display impairments in whole-body heat loss that increase body heat storage and core temperature relative to young adults during heat stress. We therefore evaluated whether whole-body heat loss in older adults was impaired on the day following prolonged work in the heat. Whole-body heat exchange and heat storage were assessed in nine older (53-64 years) males during three, 30-min bouts of semi-recumbent cycling at fixed rates of metabolic heat production (150 (Ex1), 200 (Ex2), 250 Wm (Ex3)), each separated by 15-min recovery, in hot-dry conditions (40°C, 20% relative humidity), immediately prior to (Day 1), and on the day following (Day 2), a prolonged, work simulation (~7.5 h) involving moderate-intensity intermittent exercise in hot-dry conditions (38°C, 34% relative humidity). Total heat loss (evaporative ± dry heat exchange) and metabolic heat production were measured using direct and indirect calorimetry, respectively. Body heat storage was quantified as the temporal summation of heat production and loss. Total heat loss (mean±SD) during Ex1 did not differ between Day 1 and 2 (151±15 and 147±14 Wm, respectively; P=0.27), but was attenuated on Day 2 during Ex2 (181±15 Wm) and Ex3 (218±16 Wm) relative to Day 1 (192±14 and 230±19 Wm, respectively; both P<0.01). Consequently, body heat storage throughout the protocol on Day 2 (276±114 kJ) was 31% greater than on Day 1 (191±87 kJ; P<0.01). Prolonged work in the heat causes next-day impairments in whole-body heat loss, which exacerbate heat storage and may elevate the risk of heat-injury on the following day in older workers.

Quantitative trait loci mapping of heat tolerance in broccoli (Brassica oleracea var. italica) using genotyping-by-sequencing.

PubMed

Branham, Sandra E; Stansell, Zachary J; Couillard, David M; Farnham, Mark W

2017-03-01

Five quantitative trait loci and one epistatic interaction were associated with heat tolerance in a doubled haploid population of broccoli evaluated in three summer field trials. Predicted rising global temperatures due to climate change have generated a demand for crops that are resistant to yield and quality losses from heat stress. Broccoli (Brassica oleracea var. italica) is a cool weather crop with high temperatures during production decreasing both head quality and yield. Breeding for heat tolerance in broccoli has potential to both expand viable production areas and extend the growing season but breeding efficiency is constrained by limited genetic information. A doubled haploid (DH) broccoli population segregating for heat tolerance was evaluated for head quality in three summer fields in Charleston, SC, USA. Multiple quantitative trait loci (QTL) mapping of 1,423 single nucleotide polymorphisms developed through genotyping-by-sequencing identified five QTL and one positive epistatic interaction that explained 62.1% of variation in heat tolerance. The QTL identified here can be used to develop markers for marker-assisted selection and to increase our understanding of the molecular mechanisms underlying plant response to heat stress.

The effects of radiative heat loss on microgravity flame spread

NASA Technical Reports Server (NTRS)

Fakheri, Ahmad; Olson, Sandra L.

1989-01-01

The effect of radiative heat loss from the surface of a solid material burning in a zero gravity environment in an opposed flow is studied through the use of a numerical model. Radiative heat loss is found to decrease the flame spread rate, the boundary layer thickness, and pyrolysis lengths. Blowoff extinction is predicted to occur at slower opposesd flow velocities than would occur if the radiative loss is not present. The radiative heat fluxes are comparable to the conduction fluxes, indicating the significance of the surface energy loss.

Cutaneous Heat Loss with Three Surgical Drapes, One Impervious to Moisture

PubMed Central

Maglinger, Paul E.; Sessler, Daniel I.; Lenhardt, Rainer

2005-01-01

A new surgical drape, which is impervious to moisture, presumably reduces evaporative heat loss. We compared cutaneous heat loss and skin temperature in volunteers covered with this drape to two conventional surgical drapes (Large Surgical Drape and Medline Proxima). With IRB approval and informed consent, we calculated cutaneous heat loss and skin-surface temperatures from 15 area-weighted thermal flux transducers in 8 volunteers. In random order, each of the drapes was evaluated with dry transducers and moistened transducers (simulating wet skin). After a 20-minute uncovered control period, volunteers were covered from the neck down for 40 minutes. Data were recorded continuously and averaged over 10-minutes. Results were similar for all three drapes for dry or moist conditions. Under dry conditions, baseline heat loss was 82±14 watts (W) and decreased 30% with a surgical drape (P<0.001). Under moist conditions, baseline heat loss was 231±45 W and decreased 29% with a drape covering (P<0.001). Moist skin increased heat loss 282% (P<0.001). There were no clinically important differences in skin temperature among the covers with dry or moist skin. Moist skin increased heat loss nearly three-fold, but there were no differences among the drapes. We conclude that loss is comparable with impervious and conventional drapes with either moist or dry skin. PMID:15728062

Metabolic heat production, heat loss and the circadian rhythm of body temperature in the rat.

PubMed

Refinetti, Roberto

2003-05-01

Metabolic heat production (calculated from oxygen consumption), dry heat loss (measured in a calorimeter) and body temperature (measured by telemetry) were recorded simultaneously at 6 min intervals over five consecutive days in rats maintained in constant darkness. Robust circadian rhythmicity (confirmed by chi square periodogram analysis) was observed in all three variables. The rhythm of heat production was phase-advanced by about half an hour in relation to the body temperature rhythm, whereas the rhythm of heat loss was phase-delayed by about half an hour. The balance of heat production and heat loss exhibited a daily oscillation 180 deg out of phase with the oscillation in body temperature. Computations indicated that the amount of heat associated with the generation of the body temperature rhythm (1.6 kJ) corresponds to less than 1 % of the total daily energy budget (172 kJ) in this species. Because of the small magnitude of the fraction of heat balance associated with the body temperature rhythm, it is likely that the daily oscillation in heat balance has a very slow effect on body temperature, thus accounting for the 180 deg phase difference between the rhythms of heat balance and body temperature.

Thermal Capacitance (Slug) Calorimeter Theory Including Heat Losses and Other Decaying Processes

NASA Technical Reports Server (NTRS)

Hightower, T. Mark; Olivares, Ricardo A.; Philippidis, Daniel

2008-01-01

A mathematical model, termed the Slug Loss Model, has been developed for describing thermal capacitance (slug) calorimeter behavior when heat losses and other decaying processes are not negligible. This model results in the temperature time slope taking the mathematical form of exponential decay. When data is found to fit well to this model, it allows a heat flux value to be calculated that corrects for the losses and may be a better estimate of the cold wall fully catalytic heat flux, as is desired in arc jet testing. The model was applied to the data from a copper slug calorimeter inserted during a particularly severe high heating rate arc jet run to illustrate its use. The Slug Loss Model gave a cold wall heat flux 15% higher than the value of 2,250 W/sq cm obtained from the conventional approach to processing the data (where no correction is made for losses). For comparison, a Finite Element Analysis (FEA) model was created and applied to the same data, where conduction heat losses from the slug were simulated. The heat flux determined by the FEA model was found to be in close agreement with the heat flux determined by the Slug Loss Model.

Quantitative analysis of wet-heat inactivation in bovine spongiform encephalopathy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Matsuura, Yuichi; Ishikawa, Yukiko; Bo, Xiao

2013-03-01

Highlights: ► We quantitatively analyzed wet-heat inactivation of the BSE agent. ► Infectivity of the BSE macerate did not survive 155 °C wet-heat treatment. ► Once the sample was dehydrated, infectivity was observed even at 170 °C. ► A quantitative PMCA assay was used to evaluate the degree of BSE inactivation. - Abstract: The bovine spongiform encephalopathy (BSE) agent is resistant to conventional microbial inactivation procedures and thus threatens the safety of cattle products and by-products. To obtain information necessary to assess BSE inactivation, we performed quantitative analysis of wet-heat inactivation of infectivity in BSE-infected cattle spinal cords. Using amore » highly sensitive bioassay, we found that infectivity in BSE cattle macerates fell with increase in temperatures from 133 °C to 150 °C and was not detected in the samples subjected to temperatures above 155 °C. In dry cattle tissues, infectivity was detected even at 170 °C. Thus, BSE infectivity reduces with increase in wet-heat temperatures but is less affected when tissues are dehydrated prior to the wet-heat treatment. The results of the quantitative protein misfolding cyclic amplification assay also demonstrated that the level of the protease-resistant prion protein fell below the bioassay detection limit by wet-heat at 155 °C and higher and could help assess BSE inactivation. Our results show that BSE infectivity is strongly resistant to wet-heat inactivation and that it is necessary to pay attention to BSE decontamination in recycled cattle by-products.« less

Test bench HEATREC for heat loss measurement on solar receiver tubes

NASA Astrophysics Data System (ADS)

Márquez, José M.; López-Martín, Rafael; Valenzuela, Loreto; Zarza, Eduardo

2016-05-01

In Solar Thermal Electricity (STE) plants the thermal energy of solar radiation is absorbed by solar receiver tubes (HCEs) and it is transferred to a heat transfer fluid. Therefore, heat losses of receiver tubes have a direct influence on STE plants efficiency. A new test bench called HEATREC has been developed by Plataforma Solar de Almería (PSA) in order to determinate the heat losses of receiver tubes under laboratory conditions. The innovation of this test bench consists in the possibility to determine heat losses under controlled vacuum.

Determination of clothing evaporative resistance on a sweating thermal manikin in an isothermal condition: heat loss method or mass loss method?

PubMed

Wang, Faming; Gao, Chuansi; Kuklane, Kalev; Holmér, Ingvar

2011-08-01

This paper addresses selection between two calculation options, i.e heat loss option and mass loss option, for thermal manikin measurements on clothing evaporative resistance conducted in an isothermal condition (T(manikin) = T(a) = T(r)). Five vocational clothing ensembles with a thermal insulation range of 1.05-2.58 clo were selected and measured on a sweating thermal manikin 'Tore'. The reasons why the isothermal heat loss method generates a higher evaporative resistance than that of the mass loss method were thoroughly investigated. In addition, an indirect approach was applied to determine the amount of evaporative heat energy taken from the environment. It was found that clothing evaporative resistance values by the heat loss option were 11.2-37.1% greater than those based on the mass loss option. The percentage of evaporative heat loss taken from the environment (H(e,env)) for all test scenarios ranged from 10.9 to 23.8%. The real evaporative cooling efficiency ranged from 0.762 to 0.891, respectively. Furthermore, it is evident that the evaporative heat loss difference introduced by those two options was equal to the heat energy taken from the environment. In order to eliminate the combined effects of dry heat transfer, condensation, and heat pipe on clothing evaporative resistance, it is suggested that manikin measurements on the determination of clothing evaporative resistance should be performed in an isothermal condition. Moreover, the mass loss method should be applied to calculate clothing evaporative resistance. The isothermal heat loss method would appear to overestimate heat stress and thus should be corrected before use.

Fitness-related differences in the rate of whole-body evaporative heat loss in exercising men are heat-load dependent.

PubMed

Lamarche, Dallon T; Notley, Sean R; Louie, Jeffrey C; Poirier, Martin P; Kenny, Glen P

2018-01-01

What is the central question of this study? Aerobic fitness modulates heat loss, but the heat-load threshold at which fitness-related differences in heat loss occur in young healthy men remains unclear. What is the main finding and its importance? We demonstrate using direct calorimetry that aerobic fitness modulates heat loss in a heat-load-dependent manner, with fitness-related differences occurring between young men who have low and high fitness when the heat load is ∼≥500 W. Although aerobic fitness has been known for some time to modulate heat loss, our findings define the precise heat-load threshold at which fitness-related differences occur. The effect of aerobic fitness (defined as rate of peak oxygen consumption) on heat loss during exercise is thought to be related to the level of heat stress. However, it remains unclear at what combined exercise and environmental (net) heat-load threshold these fitness-related differences occur. To identify this, we assessed whole-body heat exchange (dry and evaporative) by direct calorimetry in young (22 ± 3 years) men matched for physical characteristics with low (Low-fit; 39.8 ± 2.5 ml O 2  kg -1  min -1 ), moderate (Mod-fit; 50.9 ± 1.2 ml O 2  kg -1  min -1 ) and high aerobic fitness (High-fit; 62.0 ± 4.4 ml O 2  kg -1  min -1 ; each n = 8), during three 30 min bouts of cycling in dry heat (40°C, 12% relative humidity) at increasing rates of metabolic heat production of 300 (Ex1), 400 (Ex2) and 500 W (Ex3), each followed by a 15 min recovery period. Each group was exposed to a similar net heat load (metabolic plus ∼100 W dry heat gain; P = 0.83) during each exercise bout [∼400 (Ex1), ∼500 (Ex2) and ∼600 W (Ex3); P < 0.01]. Although evaporative heat loss was similar between groups during Ex1 (P = 0.33), evaporative heat loss was greater in the High-fit (Ex2, 466 ± 21 W; Ex3, 557 ± 26 W) compared with the Low-fit group (Ex2, 439 ± 22 W; Ex3, 511 ± 20�

Chlorophyll loss associated with heat-induced senescence in bentgrass.

PubMed

Jespersen, David; Zhang, Jing; Huang, Bingru

2016-08-01

Heat stress-induced leaf senescence is characterized by the loss of chlorophyll from leaf tissues. The objectives of this study were to examine genetic variations in the level of heat-induced leaf senescence in hybrids of colonial (Agrostis capillaris)×creeping bentgrass (Agrostis stolonifera) contrasting in heat tolerance, and determine whether loss of leaf chlorophyll during heat-induced leaf senescence was due to suppressed chlorophyll synthesis and/or accelerated chlorophyll degradation in the cool-season perennial grass species. Plants of two hybrid backcross genotypes ('ColxCB169' and 'ColxCB190') were exposed to heat stress (38/33°C, day/night) for 28 d in growth chambers. The analysis of turf quality, membrane stability, photochemical efficiency, and chlorophyll content demonstrated significant variations in the level of leaf senescence induced by heat stress between the two genotypes, with ColXCB169 exhibiting a lesser degree of decline in chlorophyll content, photochemical efficiency and membrane stability than ColXCB190. The assays of enzymatic activity or gene expression of several major chlorophyll-synthesizing (porphobilinogen deaminase, Mg-chelatase, protochlorophyllide-reductase) and chlorophyll-degrading enzymes (chlorophyllase, pheophytinase, and chlorophyll-degrading peroxidase) indicated heat-induced decline in leaf chlorophyll content was mainly due to accelerated chlorophyll degradation, as manifested by increased gene expression levels of chlorophyllase and pheophytinase, and the activity of pheophytinase (PPH), while chlorophyll-synthesizing genes and enzymatic activities were not differentially altered by heat stress in the two genotypes. The analysis of heat-induced leaf senescence of pph mutants of Arabidopsis further confirmed that PPH could be one enzymes that plays key roles in regulating heat-accelerated chlorophyll degradation. Further research on enzymes responsible in part for the loss of chlorophyll during heat

Heat Loss May Explain Bill Size Differences between Birds Occupying Different Habitats

PubMed Central

Greenberg, Russell; Cadena, Viviana; Danner, Raymond M.; Tattersall, Glenn

2012-01-01

Background Research on variation in bill morphology has focused on the role of diet. Bills have other functions, however, including a role in heat and water balance. The role of the bill in heat loss may be particularly important in birds where water is limiting. Song sparrows localized in coastal dunes and salt marsh edge (Melospiza melodia atlantica) are similar in size to, but have bills with a 17% greater surface area than, those that live in mesic habitats (M. m. melodia), a pattern shared with other coastal sparrows. We tested the hypotheses that sparrows can use their bills to dissipate “dry” heat, and that heat loss from the bill is higher in M. m. atlantica than M. m. melodia, which would indicate a role of heat loss and water conservation in selection for bill size. Methodology/Principal Findings Bill, tarsus, and body surface temperatures were measured using thermal imaging of sparrows exposed to temperatures from 15–37°C and combined with surface area and physical modeling to estimate the contribution of each body part to total heat loss. Song sparrow bills averaged 5–10°C hotter than ambient. The bill of M. m atlantica dissipated up to 33% more heat and 38% greater proportion of total heat than that of M. m. melodia. This could potentially reduce water loss requirements by approximately 7.7%. Conclusions/Significance This >30% higher heat loss in the bill of M. m. atlantica is independent of evaporative water loss and thus could play an important role in the water balance of sparrows occupying the hot and exposed dune/salt marsh environments during the summer. Heat loss capacity and water conservation could play an important role in the selection for bill size differences between bird populations and should be considered along with trophic adaptations when studying variation in bill size. PMID:22848413

Influence of a Simple Heat Loss Profile on a Pure Diffusion Flame

NASA Technical Reports Server (NTRS)

Ray, Anjan; Wichman, Indrek S.

1996-01-01

The presence of soot on the fuel side of a diffusion flame results in significant radiative heat losses. The influence of a fuel side heat loss zone on a pure diffusion flame established between a fuel and an oxidizer wall is investigated by assuming a hypothetical sech(sup 2) heat loss profile. The intensity and width of the loss zone are parametrically varied. The loss zone is placed at different distances from the Burke-Schumann flame location. The migration of the temperature and reactivity peaks are examined for a variety of situations. For certain cases the reaction zone breaks through the loss zone and relocates itself on the fuel side of the loss zone. In all cases the temperature and reactivity peaks move toward the fuel side with increased heat losses. The flame structure reveals that the primary balance for the energy equation is between the reaction term and the diffusion term. Extinction plots are generated for a variety of situations. The heat transfer from the flame to the walls and the radiative fraction is also investigated, and an analytical correlation formula, derived in a previous study, is shown to produce excellent predictions of our numerical results when an O(l) numerical multiplicative constant is employed.

A Global Assessment of Oceanic Heat Loss: Conductive Cooling and Hydrothermal Redistribution of Heat

NASA Astrophysics Data System (ADS)

Hasterok, D. P.; Chapman, D. S.; Davis, E. E.

2011-12-01

A new dataset of ~15000 oceanic heat flow measurements is analyzed to determine the conductive heat loss through the seafloor. Many heat flow values in seafloor younger than 60 Ma are lower than predicted by models of conductively cooled lithosphere. This heat flow deficit is caused by ventilated hydrothermal circulation discharging at crustal outcrops or through thin sedimentary cover. Globally filtering of heat flow data to retain sites with sediment cover >400 m thick and located >60 km from the nearest seamount minimizes the effect of hydrothermal ventilation. Filtered heat flow exhibit a much higher correlation coefficient with seafloor age (up to 0.95 for filtered data in contrast to 0.5 for unfiltered data) and lower variability (reduction by 30%) within an age bin. A small heat flow deficit still persists at ages <25 Ma, possibly as a result of global filtering limitations and incomplete thermal rebound following sediment burial. Detailed heat flow surveys co-located with seismic data can identify environments favoring conductive heat flow; heat flow collected in these environments is higher than that determined by the global dataset, and is more consistent with conductive cooling of the lithosphere. The new filtered data analysis and a growing number of site specific surveys both support estimates of global heat loss in the range 40-47 TW. The estimated hydrothermal deficit is consistent with estimates from geochemical studies ~7 TW, but is a few TW lower than previous estimates derived from heat flow determinations.

Modeling heat loss from the udder of a dairy cow.

PubMed

Gebremedhin, Kifle G; Wu, Binxin

2016-07-01

A mechanistic model that predicts sensible and latent heat fluxes from the udder of a dairy cow was developed. The prediction of the model was spot validated against measured data from the literature, and the result agreed within 7% of the measured value for the same ambient temperature. A dairy cow can lose a significant amount of heat (388W/m(2)) from the udder. This suggests that the udder could be considered as a heat sink. The temperature profile through the udder tissue (core to skin) approached the core temperature for an air temperature ≥37°C whereas the profile decreased linearly from the core to skin surface for an air temperature less than 37°C. Sensible heat loss was dominant when ambient air temperature was less than 37.5°C but latent heat loss was greater than sensible heat loss when air temperature was ≥37.5°C. The udder could lose a total (sensible + latent) heat flux of 338W/m(2) at an ambient temperature of 35°C and blood-flow rate of 3.2×10(-3)m(3)/(sm(3) tissue). The results of this study suggests that, in time of heat stress, a dairy cow could be cooled by cooling the udder only (e.g., using an evaporative cooling jacket). Copyright © 2016 Elsevier Ltd. All rights reserved.

Causes and Consequences of Exceptional North Atlantic Heat Loss in Recent Winters

NASA Astrophysics Data System (ADS)

Josey, Simon; Grist, Jeremy; Duchez, Aurelie; Frajka-Williams, Eleanor; Hirschi, Joel; Marsh, Robert; Sinha, Bablu

2016-04-01

The mid-high latitude North Atlantic loses large amounts of heat to the atmosphere in winter leading to dense water formation. An examination of reanalysis datasets (ERA-Interim, NCEP/NCAR) reveals that heat loss in the recent winters 2013-14 and 2014-15 was exceptionally strong. The causes and consequences of this extraordinary ocean heat loss will be discussed. In 2013-2014, the net air-sea heat flux anomaly averaged over the whole winter exceeded 100 Wm-2 in the eastern subpolar gyre (the most extreme in the period since 1979 spanned by ERA-Interim). The causes of this extreme heat loss will be shown to be severe latent and sensible heat fluxes driven primarily by anomalously strong westerly airflows from North America and northerly airflows originating in the Nordic Seas. The associated sea level pressure anomaly field reflects the dominance of the second mode of atmospheric variability, the East Atlantic Pattern (EAP) over the North Atlantic Oscillation (NAO) in this winter. The extreme winter heat loss had a significant impact on the ocean extending from the sea surface into the deeper layers and a re-emergent cold Sea Surface Temperature (SST) anomaly is evident in November 2014. The following winter 2014-15 experienced further extreme heat loss that served to amplify the strength of the re-emergent SST anomaly. By summer 2015, an unprecedented cold mid-latitude North Atlantic Ocean surface temperature anomaly is evident in observations and has been widely referred to as the 'big blue blob'. The role played by the extreme surface heat loss in the preceding winters in generating this feature and it subsequent evolution through winter 2015-16 will be explored.

A method for the measurement of physiologic evaporative water loss.

DOT National Transportation Integrated Search

1963-10-01

The precise measurement of evaporative water loss is essential to an accurate evaluation of this avenue of heat loss in acute and chronic exposures to heat. In psychological studies, the quantitative measurement of palmar sweating plays an equally im...

Oscillating flow loss test results in Stirling engine heat exchangers

NASA Technical Reports Server (NTRS)

Koester, G.; Howell, S.; Wood, G.; Miller, E.; Gedeon, D.

1990-01-01

The results are presented for a test program designed to generate a database of oscillating flow loss information that is applicable to Stirling engine heat exchangers. The tests were performed on heater/cooler tubes of various lengths and entrance/exit configurations, on stacked and sintered screen regenerators of various wire diameters and on Brunswick and Metex random fiber regenerators. The test results were performed over a range of oscillating flow parameters consistent with Stirling engine heat exchanger experience. The tests were performed on the Sunpower oscillating flow loss rig which is based on a variable stroke and variable frequency linear drive motor. In general, the results are presented by comparing the measured oscillating flow losses to the calculated flow losses. The calculated losses are based on the cycle integration of steady flow friction factors and entrance/exit loss coefficients.

Ice Slurry Ingestion Leads to a Lower Net Heat Loss during Exercise in the Heat.

PubMed

Morris, Nathan B; Coombs, Geoff; Jay, Ollie

2016-01-01

To compare the reductions in evaporative heat loss from the skin (Esk) to internal heat loss (Hfluid) induced by ice slurry (ICE) ingestion relative to 37 °C fluid and the accompanying body temperature and local thermoeffector responses during exercise in warm, dry conditions (33.5 °C ± 1.4 °C; 23.7% ± 2.6% relative humidity [RH]). Nine men cycled at approximately 55% VO2peak for 75 min and ingested 3.2 mL · kg(-1) aliquots of 37 °C fluid or ICE after 15, 30, and 45 min of exercise. Metabolic heat production (M-W), rectal temperature (Tre), mean skin temperature (Tsk), whole-body sweat loss (WBSL), local sweat rate (LSR), and skin blood flow (SkBF) were measured throughout. Net heat loss (HLnet) and heat storage (S) were estimated using partitional calorimetry. Relative to the 37 °C trial, M-W was similar (P = 0.81) with ICE ingestion; however, the 200 ± 20 kJ greater Hfluid (P < 0.001) with ICE ingestion was overcompensated by a 381 ± 199-kJ lower Esk (P < 0.001). Net heat loss (HLnet) was consequently 131 ± 120 kJ lower (P = 0.01) and S was greater (P = 0.05) with ICE ingestion compared with 37 °C fluid ingestion. Concurrently, LSR and WBSL were lower by 0.16 ± 0.14 mg · min(-1) · cm(-2) (P < 0.01) and 191 ± 122 g (P < 0.001), respectively, and SkBF tended to be lower (P = 0.06) by 5.4%maxAU ± 13.4%maxAU in the ICE trial. Changes in Tre and Tsk were similar throughout exercise with ICE compared to 37 °C fluid ingestion. Relative to 37 °C, ICE ingestion caused disproportionately greater reductions in Esk relative to Hfluid, resulting in a lower HLnet and greater S. Mechanistically, LSR and possibly SkBF were suppressed independently of Tre or Tsk, reaffirming the concept of human abdominal thermoreception. From a heat balance perspective, recommendations for ICE ingestion during exercise in warm, dry conditions should be reconsidered.

Heat stress causes substantial labour productivity loss in Australia

NASA Astrophysics Data System (ADS)

Zander, Kerstin K.; Botzen, Wouter J. W.; Oppermann, Elspeth; Kjellstrom, Tord; Garnett, Stephen T.

2015-07-01

Heat stress at the workplace is an occupational health hazard that reduces labour productivity. Assessment of productivity loss resulting from climate change has so far been based on physiological models of heat exposure. These models suggest productivity may decrease by 11-27% by 2080 in hot regions such as Asia and the Caribbean, and globally by up to 20% in hot months by 2050. Using an approach derived from health economics, we describe self-reported estimates of work absenteeism and reductions in work performance caused by heat in Australia during 2013/2014. We found that the annual costs were US$655 per person across a representative sample of 1,726 employed Australians. This represents an annual economic burden of around US$6.2 billion (95% CI: 5.2-7.3 billion) for the Australian workforce. This amounts to 0.33 to 0.47% of Australia’s GDP. Although this was a period when many Australians experienced what is at present considered exceptional heat, our results suggest that adaptation measures to reduce heat effects should be adopted widely if severe economic impacts from labour productivity loss are to be avoided if heat waves become as frequent as predicted.

Quantitative Comparison of Photothermal Heat Generation between Gold Nanospheres and Nanorods.

PubMed

Qin, Zhenpeng; Wang, Yiru; Randrianalisoa, Jaona; Raeesi, Vahid; Chan, Warren C W; Lipiński, Wojciech; Bischof, John C

2016-07-21

Gold nanoparticles (GNPs) are widely used for biomedical applications due to unique optical properties, established synthesis methods, and biological compatibility. Despite important applications of plasmonic heating in thermal therapy, imaging, and diagnostics, the lack of quantification in heat generation leads to difficulties in comparing the heating capability for new plasmonic nanostructures and predicting the therapeutic and diagnostic outcome. This study quantifies GNP heat generation by experimental measurements and theoretical predictions for gold nanospheres (GNS) and nanorods (GNR). Interestingly, the results show a GNP-type dependent agreement between experiment and theory. The measured heat generation of GNS matches well with theory, while the measured heat generation of GNR is only 30% of that predicted theoretically at peak absorption. This then leads to a surprising finding that the polydispersity, the deviation of nanoparticle size and shape from nominal value, significantly influences GNR heat generation (>70% reduction), while having a limited effect for GNS (<10% change). This work demonstrates that polydispersity is an important metric in quantitatively predicting plasmonic heat generation and provides a validated framework to quantitatively compare the heating capabilities between gold and other plasmonic nanostructures.

Quantitative Comparison of Photothermal Heat Generation between Gold Nanospheres and Nanorods

NASA Astrophysics Data System (ADS)

Qin, Zhenpeng; Wang, Yiru; Randrianalisoa, Jaona; Raeesi, Vahid; Chan, Warren C. W.; Lipiński, Wojciech; Bischof, John C.

2016-07-01

Gold nanoparticles (GNPs) are widely used for biomedical applications due to unique optical properties, established synthesis methods, and biological compatibility. Despite important applications of plasmonic heating in thermal therapy, imaging, and diagnostics, the lack of quantification in heat generation leads to difficulties in comparing the heating capability for new plasmonic nanostructures and predicting the therapeutic and diagnostic outcome. This study quantifies GNP heat generation by experimental measurements and theoretical predictions for gold nanospheres (GNS) and nanorods (GNR). Interestingly, the results show a GNP-type dependent agreement between experiment and theory. The measured heat generation of GNS matches well with theory, while the measured heat generation of GNR is only 30% of that predicted theoretically at peak absorption. This then leads to a surprising finding that the polydispersity, the deviation of nanoparticle size and shape from nominal value, significantly influences GNR heat generation (>70% reduction), while having a limited effect for GNS (<10% change). This work demonstrates that polydispersity is an important metric in quantitatively predicting plasmonic heat generation and provides a validated framework to quantitatively compare the heating capabilities between gold and other plasmonic nanostructures.

Theoretical modeling of time-dependent skin temperature and heat losses during whole-body cryotherapy: A pilot study.

PubMed

Polidori, G; Marreiro, A; Pron, H; Lestriez, P; Boyer, F C; Quinart, H; Tourbah, A; Taïar, R

2016-11-01

This article establishes the basics of a theoretical model for the constitutive law that describes the skin temperature and thermolysis heat losses undergone by a subject during a session of whole-body cryotherapy (WBC). This study focuses on the few minutes during which the human body is subjected to a thermal shock. The relationship between skin temperature and thermolysis heat losses during this period is still unknown and have not yet been studied in the context of the whole human body. The analytical approach here is based on the hypothesis that the skin thermal shock during a WBC session can be thermally modelled by the sum of both radiative and free convective heat transfer functions. The validation of this scientific approach and the derivation of temporal evolution thermal laws, both on skin temperature and dissipated thermal power during the thermal shock open many avenues of large scale studies with the aim of proposing individualized cryotherapy protocols as well as protocols intended for target populations. Furthermore, this study shows quantitatively the substantial imbalance between human metabolism and thermolysis during WBC, the explanation of which remains an open question. Copyright © 2016 Elsevier Ltd. All rights reserved.

Fitness-related differences in the rate of whole-body total heat loss in exercising young healthy women are heat-load dependent.

PubMed

Lamarche, Dallon T; Notley, Sean R; Poirier, Martin P; Kenny, Glen P

2018-03-01

What is the central question of this study? Aerobic fitness modulates heat loss, albeit the heat load at which fitness-related differences occur in young healthy women remains unclear. What is the main finding and its importance? We demonstrate using direct calorimetry that fitness modulates heat loss in a heat-load dependent manner, with differences occurring between young women of low and high fitness and matched physical characteristics when the metabolic heat load is at least 400 W in hot, dry conditions. Although fitness has been known for some time to modulate heat loss, our findings define the metabolic heat load at which fitness-related differences occur. Aerobic fitness has recently been shown to alter heat loss capacity in a heat-load dependent manner in young men. However, given that sex-related differences in heat loss capacity exist, it is unclear whether this response is consistent in women. We therefore assessed whole-body total heat loss in young (21 ± 3 years old) healthy women matched for physical characteristics, but with low (low-fit; 35.8 ± 4.5 ml O 2  kg -1  min -1 ) or high aerobic fitness (high-fit; 53.1 ± 5.1 ml O 2  kg -1  min -1 ; both n = 8; indexed by peak oxygen consumption), during three 30 min bouts of cycling performed at increasing rates of metabolic heat production of 250 (Ex1), 325 (Ex2) and 400 W (Ex3), each separated by a 15 min recovery, in hot, dry conditions (40°C, 11% relative humidity). Whole-body total heat loss (evaporative ± dry heat exchange) and metabolic heat production were measured using direct and indirect calorimetry, respectively. Body heat content was measured as the temporal summation of heat production and loss. Total heat loss did not differ during Ex1 (low-fit, 215 ± 16 W; high-fit, 231 ± 20 W; P > 0.05) and Ex2 (low-fit, 278 ± 15 W; high-fit, 301 ± 20 W; P > 0.05), but was lower in the low-fit (316 ± 21 W) compared with the high-fit women (359 ± 32�

Parabolic trough receiver heat loss and optical efficiency round robin 2015/2016

NASA Astrophysics Data System (ADS)

Pernpeintner, Johannes; Schiricke, Björn; Sallaberry, Fabienne; de Jalón, Alberto García; López-Martín, Rafael; Valenzuela, Loreto; de Luca, Antonio; Georg, Andreas

2017-06-01

A round robin for parabolic trough receiver heat loss and optical efficiency in the laboratory was performed between five institutions using five receivers in 2015/2016. Heat loss testing was performed at three cartridge heater test benches and one Joule heating test bench in the temperature range between 100 °C and 550 °C. Optical efficiency testing was performed with two spectrometric test bench and one calorimetric test bench. Heat loss testing results showed standard deviations at the order of 6% to 12 % for most temperatures and receivers and a standard deviation of 17 % for one receiver at 100 °C. Optical efficiency is presented normalized for laboratories showing standard deviations of 0.3 % to 1.3 % depending on the receiver.

Sliding, Insulating Window Panel Reduces Heat Loss.

ERIC Educational Resources Information Center

School Business Affairs, 1984

1984-01-01

A new sliding insulated panel reduces window heat loss up to 86 percent, and infiltration 60-90 percent, paying for itself in 3-9 years. This article discusses the panel's use and testing in the upper Midwest, reporting both technical characteristics and users' reactions. (MCG)

Heat loss during carbon dioxide insufflation: comparison of a nebulization based humidification device with a humidification and heating system.

PubMed

Noll, Eric; Schaeffer, Roland; Joshi, Girish; Diemunsch, Sophie; Koessler, Stefanie; Diemunsch, Pierre

2012-12-01

This study compared the heat loss observed with the use of MR860 AEA Humidifier™ system (Fisher & Paykel Healthcare, New Zealand), which humidifies and heats the insufflated CO(2), and the use of the AeronebPro™ device (Aerogen, Ireland), which humidifies but does not heat the insufflated CO(2). With institutional approval, 16 experiments were conducted in 4 pigs. Each animal, acting as its own control, was studied at 8-day intervals in randomized sequence with the following four conditions: (1) control (C) no pneumoperitoneum; (2) standard (S) insufflation with nonhumidified, nonheated CO(2); (3) Aeroneb™ (A): insufflation with humidified, nonheated CO(2); and (4) MR860 AEA humidifier™ (MR): insufflation with humidified and heated CO(2). The measured heat loss after 720L CO(2) insufflation during the 4 h was 1.03 ± 0.75 °C (mean ± SEM) in group C; 3.63 ± 0.31 °C in group S; 3.03 ± 0.39 °C in group A; and 1.98 ± 0.09 °C in group MR. The ANOVA showed a significant difference with time (p = 0.0001) and with the insufflation technique (p = 0.024). Heat loss in group C was less than in group S after 60 min (p = 0.03), less than in group A after 70 min (p = 0.03), and less than in group MR after 150 min (p = 0.03). The heat loss in group MR was less than in group S after 50 min (p = 0.04) and less than in group A after 70 min (p = 0.02). After 160 min, the heat loss in group S was greater than in group A (p = 0.03). As far as heat loss is concerned, for laparoscopic procedures of less than 60 min, there is no benefit of using any humidification with or without heating. However, for procedures greater than 60 min, use of heating along with humidification, is superior.

Experimentally-determined external heat loss of automotive gas turbine engine

NASA Technical Reports Server (NTRS)

Meng, P. R.; Wulf, R. F.

1975-01-01

An external heat balance was conducted on a 150 HP two-shaft automotive gas turbine engine. The engine was enclosed in a calorimeter box and the temperature change of cooling air passing through the box was measured. Cooling airflow ranges of 1.6 to 2.1 lb-per-second and 0.8 to 1.1 lb-per-second were used. The engine housing heat loss increased as the cooling airflow through the calorimeter box was increased, as would be the case in a moving automobile. The heat balance between the total energy input and the sum of shaft power output and various losses compared within 30 percent at engine idle speeds and within 7 percent at full power.

Whole-body heat loss during exercise in the heat is not impaired in type 1 diabetes.

PubMed

Stapleton, Jill M; Yardley, Jane E; Boulay, Pierre; Sigal, Ronald J; Kenny, Glen P

2013-09-01

The objective of this study is to determine whether individuals with type 1 diabetes exhibit impairments in local and whole-body heat loss responses that could affect core temperature regulation during exercise in the heat compared with matched, nondiabetic individuals. Twelve otherwise healthy individuals with type 1 diabetes (HbA1c = 7.7% ± 0.3%) and 12 controls matched for age, sex, body surface area, and physical fitness cycled continuously for 60 min at a set rate of metabolic heat production (approximately 400 W) in a whole-body direct calorimeter (35°C and 20% relative humidity). Local sweat rate (ventilated capsule) was measured on the back and skin blood flow (laser Doppler velocimetry) on the forearm. Core (rectal and esophageal) and mean skin temperatures and heart rate were measured continuously. Whole-body heat exchange and change in body heat content were measured using simultaneous direct whole-body and indirect calorimetry. The change (mean ± SE) in body heat content was similar between groups during exercise (diabetes, 409 ± 27 kJ; control, 386 ± 33 kJ; P = 0.584) and recovery (diabetes, -115 ± 16 kJ; control, -93 ± 24 kJ; P = 0.457). Local heat loss responses of sweating (P = 0.783) and skin blood flow (P = 0.078) as well as rectal temperature (diabetes, 37.87°C ± 0.10°C; control, 37.85°C; ± 0.13°C; P = 0.977) and heart rate (diabetes, 130 ± 9 beats·min, vs control, 126 ± 8 beats·min, P = 0.326) were comparable at the end of the exercise period. During light-to-moderate-intensity exercise performed under conditions permitting full sweat evaporation, otherwise healthy type 1 diabetic individuals did not show impaired heat loss responses during heat exposure when compared with matched individuals without diabetes.

Correction of the heat loss method for calculating clothing real evaporative resistance.

PubMed

Wang, Faming; Zhang, Chengjiao; Lu, Yehu

2015-08-01

In the so-called isothermal condition (i.e., Tair [air temperature]=Tmanikin [manikin temperature]=Tr [radiant temperature]), the actual energy used for moisture evaporation detected by most sweating manikins was underestimated due to the uncontrolled fabric 'skin' temperature Tsk,f (i.e., Tsk,fheat loss from the wet fabric 'skin'-clothing system was proposed and experimentally validated on a 'Newton' sweating manikin. The real evaporative resistance of five clothing ensembles and the nude fabric 'skin' calculated by the corrected heat loss method was also reported and compared with that by the mass loss method. Results revealed that, depending on the types of tested clothing, different amounts of heat were drawn from the ambient environment. In general, a greater amount of heat was drawn from the ambient environment by the wet fabric 'skin'-clothing system in lower thermal insulation clothing than that in higher insulation clothing. There were no significant differences between clothing real evaporative resistances calculated by the corrected heat loss method and those by the mass loss method. It was therefore concluded that the correction method proposed in this study has been successfully validated. Copyright © 2015 Elsevier Ltd. All rights reserved.

Systematic losses of outdoor production from heat stress and climate change

NASA Astrophysics Data System (ADS)

Buzan, J. R.; Huber, M.

2017-12-01

Heat stress impacts humans today with heat waves, worker reductions, and health issues. Here we show novel results in labor productivity for outdoor work due to global warming. We use the HumanIndexMod to calculate 4x daily values of Simplified Wet Bulb Globe Temperature index (sWBGT) from the CMIP5 archive normalized by global mean surface temperature changes. Previous work shows that scaling of sWBGT is robust across the CMIP5 archive. We calculate total annual outdoor labor capacity from our scaled sWBGT results. Our results show modern day losses due to heat stress impacting outdoor work for low latitudes (and parts of Eastern China and the Southern United States). At 2°C of climate change, up to 20% losses to total capacity impact Midwestern United States, while the Southern United States suffers >20% losses. Western Coastal Africa suffers annual losses at >80%, along with the Amazon Basin and the greater South East Asia region. India suffers losses >50% annually. At +5°C, the estimated mean global change by 2100, the Equatorial region (Northern Australia and Northern Bolivia to Western Coastal Africa and Southern India) has complete cessation of annual outdoor work. The Midwest United States suffers losses up to 30%, and the Gulf of Mexico suffers losses >50%. Our results imply that small changes in global mean surface temperature (2°C) will lead to crippling losses to outdoor work annually, and ≥5°C losses will lead to cessation of labor for more than half the world's population.

Predicting TDN losses from heat damaged hays and haylages with NIR

USDA-ARS?s Scientific Manuscript database

During the storage of hay or haylage, heating damage may occur and lead to losses of available protein and digestible nutrients. Recent research indicates that losses of TDN may be more significant economically than losses of available protein. Our objectives for this study were to establish a near-...

Modelling of labour productivity loss due to climate change: HEAT-SHIELD

NASA Astrophysics Data System (ADS)

Kjellstrom, Tord; Daanen, Hein

2016-04-01

Climate change will bring higher heat levels (temperature and humidity combined) to large parts of the world. When these levels reach above thresholds well defined by human physiology, the ability to maintain physical activity levels decrease and labour productivity is reduced. This impact is of particular importance in work situations in areas with long high intensity hot seasons, but also affects cooler areas during heat waves. Our modelling of labour productivity loss includes climate model data of the Inter-Sectoral Impact Model Inter-comparison Project (ISI-MIP), calculations of heat stress indexes during different months, estimations of work capacity loss and its annual impacts in different parts of the world. Different climate models will be compared for the Representative Concentration Pathways (RCPs) and the outcomes of the 2015 Paris Climate Conference (COP21) agreements. The validation includes comparisons of modelling outputs with actual field studies using historical heat data. These modelling approaches are a first stage contribution to the European Commission funded HEAT-SHIELD project.

Simulation of heat losses and ground temperatures for district-heating culverts. Comparison with field experiments for well-insulated, damaged, and extra-insulated culverts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hagentoft, C.E.

1986-01-01

Many old district-heating culverts are in bad condition due to the entry of water into the thermal insulation. The thermal conductivity, and thereby the heat loss from the culvert, is much larger for a wet than a dry thermal insulation. The high energy prices make it interesting and necessary to find the water-damaged parts of the district-heating culvert and improve the thermal insulation so that a reduction in the heat losses is obtained. The aim of the project is to develop a simple field method to determine the heat loss and the condition of the culvert. The method is basedmore » on the measurement of the temperature on the top of the culvert and a classification of the soil. The classification of the soil gives an estimation of its thermal conductivity. The heat loss and the reduction in heat loss due to an extra insulation is estimated from these data. Five different types of culverts were tested: two types of asbestos cement culverts, one concrete culvert, and two aerated concrete culverts. The comparison of the measured temperatures and the temperatures obtained from the simulations is reported in the study.« less

Influence of the wetting state of a heated surface on heat transfer and pressure loss in an evaporator tube

DOE Office of Scientific and Technical Information (OSTI.GOV)

Koehler, W; Hein, D

1986-09-01

The influence of the wetting state of a heated surface on heat transfer and pressure loss in an evaporator tube was investigated for a parameter range occurring in fossil-fired steam generators. Included in the analysis are quantities which determine the wetting state in steady and transient flow. The experimental work consists of the following: Occurrence of critical heat flux (CHF) and post-CHF heat transfer in a vertical upflow evaporator tube; influence of pressure and enthalpy transients on heat transfer in the unwetted region; influence of pipe orientation on heat transfer; and two phase flow pressure loss in wetted and unwettedmore » region. Based on these experiments a method of predicting CHF for a vertical upflow evaporator tube was developed. The heat transfer in the unwetted region was newly formulated taking into account thermal nonequilibrium between the water and steam phases. Wall temperature excursions during pressure and enthalpy transients are interpreted with the help of the boiling curve and the Leidenfrost phenomenon. A method is developed by means of which it is possible to determine the influence of the pipe orientation on the location of the boiling crisis as well as on the heat transfer in the unwetted region. The influence of the wetting state of the heated surface on the two phase flow pressure loss is interpreted as ''Wall effect'' and is calculated using a simplified computer model. 68 refs., 83 figs.« less

Effects of heating durations on normal concrete residual properties: compressive strength and mass loss

NASA Astrophysics Data System (ADS)

Nazri, Fadzli Mohamed; Shahidan, Shahiron; Khaida Baharuddin, Nur; Beddu, Salmia; Hisyam Abu Bakar, Badorul

2017-11-01

This study investigates the effects of high temperature with five different heating durations on residual properties of 30 MPa normal concrete. Concrete cubes were being heated up to 600°C for 30, 60, 90, 120 and 150 minutes. The temperature will keep constant for 30, 60, 90, 120 and 150 minutes. The standard temperature-time curve ISO 834 is referred to. After heating the specimen were left to cool in the furnace and removed. After cooling down to ambient temperature, the residual mass and residual compressive strength were observed. The obtained result shows that, the compressive strength of concrete decrease as the heating duration increases. This heating duration influence, might affects the loss of free water present and decomposition of hydration products in concrete. As the heating duration increases, the amount of water evaporated also increases led to loss in concrete mass. Conclusively, the percentage of mass and compressive strength loss increased as the heating duration increased.

Reducing heat loss from the energy absorber of a solar collector

DOEpatents

Chao, Bei Tse; Rabl, Ari

1976-01-01

A device is provided for reducing convective heat loss in a cylindrical radiant energy collector. It includes a curved reflective wall in the shape of the arc of a circle positioned on the opposite side of the exit aperture from the reflective side walls of the collector. Radiant energy exiting the exit aperture is directed by the curved wall onto an energy absorber such that the portion of the absorber upon which the energy is directed faces downward to reduce convective heat loss from the absorber.

Heat loss through the glabrous skin surfaces of heavily insulated, heat-stressed individuals.

PubMed

Grahn, D A; Dillon, J L; Heller, H C

2009-07-01

Insulation reduces heat exchange between a body and the environment. Glabrous (nonhairy) skin surfaces (palms of the hands, soles of the feet, face, and ears) constitute a small percentage of total body surface area but contain specialized vascular structures that facilitate heat loss. We have previously reported that cooling the glabrous skin surfaces is effective in alleviating heat stress and that the application of local subatmospheric pressure enhances the effect. In this paper, we compare the effects of cooling multiple glabrous skin surfaces with and without vacuum on thermal recovery in heavily insulated heat-stressed individuals. Esophageal temperatures (T(es)) and heart rates were monitored throughout the trials. Water loss was determined from pre- and post-trial nude weights. Treadmill exercise (5.6 km/h, 9-16% slope, and 25-45 min duration) in a hot environment (41.5 degrees C, 20-30% relative humidity) while wearing insulating pants and jackets was used to induce heat stress (T(es)>or=39 degrees C). For postexercise recovery, the subjects donned additional insulation (a balaclava, winter gloves, and impermeable boot covers) and rested in the hot environment for 60 min. Postexercise cooling treatments included control (no cooling) or the application of a 10 degrees C closed water circulating system to (a) the hand(s) with or without application of a local subatmospheric pressure, (b) the face, (c) the feet, or (d) multiple glabrous skin regions. Following exercise induction of heat stress in heavily insulated subjects, the rate of recovery of T(es) was 0.4+/-0.2 degrees C/h(n=12), but with application of cooling to one hand, the rate was 0.8+/-0.3 degrees C/h(n=12), and with one hand cooling with subatmospheric pressure, the rate was 1.0+/-0.2 degrees C/h(n=12). Cooling alone yielded two responses, one resembling that of cooling with subatmospheric pressure (n=8) and one resembling that of no cooling (n=4). The effect of treating multiple surfaces was

Relationships between micronutrient losses in sweat and blood pressure among heat-exposed steelworkers.

PubMed

Tang, Yong-Mei; Wang, Dao-Gang; Li, Jun; Li, Xing-Hua; Wang, Qian; Liu, Nan; Liu, Wei-Tian; Li, Ying-Xue

2016-06-10

We aimed to examine the effect of micronutrient losses through sweat on blood pressure (BP) among heat-exposed steelworkers. A total of 224 heat-exposed male steelworkers from an ironworks facility were evaluated in July 2012. We measured the Wet Bulb Globe Temperature Index to evaluate the level of heat stress in the workplace. We collected sweat from the workers during an eight-hour work, and then we measured the micronutrients in the sweat. We also measured the BP of each worker. The results revealed that vitamin C, potassium, and calcium losses in sweat were positively correlated with systolic (SBP) and diastolic (DBP) blood pressure (all P<0.05). A linear stepwise regression analysis revealed that potassium, and calcium losses in sweat adversely affected SBP and DBP (all P<0.05). An analysis of covariance showed that SBP increased when potassium or calcium losses in sweat were >900 mg, or >100 mg, respectively. Further, DBP increased when potassium or calcium losses in sweat were >600 mg or >130 mg, respectively. Therefore, vitamin C, potassium, and calcium losses in sweat may adversely effect BP. To help steelworkers maintain healthy BP, facilities with high temperatures should try to lower environmental temperatures to reduce vitamin C, potassium, and calcium losses in sweat. Additionally, heat-exposed steelworkers may need to increase their dietary intakes of vitamin C, potassium, and calcium. Further research is needed to confirm these findings and support these recommendations.

Relationships between micronutrient losses in sweat and blood pressure among heat-exposed steelworkers

PubMed Central

TANG, Yong-Mei; WANG, Dao-Gang; LI, Jun; LI, Xing-Hua; WANG, Qian; LIU, Nan; LIU, Wei-Tian; LI, Ying-Xue

2016-01-01

We aimed to examine the effect of micronutrient losses through sweat on blood pressure (BP) among heat-exposed steelworkers. A total of 224 heat-exposed male steelworkers from an ironworks facility were evaluated in July 2012. We measured the Wet Bulb Globe Temperature Index to evaluate the level of heat stress in the workplace. We collected sweat from the workers during an eight-hour work, and then we measured the micronutrients in the sweat. We also measured the BP of each worker. The results revealed that vitamin C, potassium, and calcium losses in sweat were positively correlated with systolic (SBP) and diastolic (DBP) blood pressure (all P<0.05). A linear stepwise regression analysis revealed that potassium, and calcium losses in sweat adversely affected SBP and DBP (all P<0.05). An analysis of covariance showed that SBP increased when potassium or calcium losses in sweat were >900 mg, or >100 mg, respectively. Further, DBP increased when potassium or calcium losses in sweat were >600 mg or >130 mg, respectively. Therefore, vitamin C, potassium, and calcium losses in sweat may adversely effect BP. To help steelworkers maintain healthy BP, facilities with high temperatures should try to lower environmental temperatures to reduce vitamin C, potassium, and calcium losses in sweat. Additionally, heat-exposed steelworkers may need to increase their dietary intakes of vitamin C, potassium, and calcium. Further research is needed to confirm these findings and support these recommendations. PMID:27087421

Heat loss distribution: Impedance and thermal loss analyses in LiFePO4/graphite 18650 electrochemical cell

NASA Astrophysics Data System (ADS)

Balasundaram, Manikandan; Ramar, Vishwanathan; Yap, Christopher; Lu, Li; Tay, Andrew A. O.; Palani, Balaya

2016-10-01

We report here thermal behaviour and various components of heat loss of 18650-type LiFePO4/graphite cell at different testing conditions. In this regard, the total heat generated during charging and discharging processes at various current rates (C) has been quantified in an Accelerating Rate Calorimeter experiment. Irreversible heat generation, which depends on applied current and internal cell resistance, is measured under corresponding charge/discharge conditions using intermittent pulse techniques. On the other hand, reversible heat generation which depends on entropy changes of the electrode materials during the cell reaction is measured from the determination of entropic coefficient at various states of charge/discharge. The contributions of irreversible and reversible heat generation to the total heat generation at both high and low current rates are evaluated. At every state of charge/discharge, the nature of the cell reaction is found to be either exothermic or endothermic which is especially evident at low C rates. In addition, electrochemical impedance spectroscopy measurements are performed on above 18650 cells at various states of charge to determine the components of internal resistance. The findings from the impedance and thermal loss analysis are helpful for understanding the favourable states of charge/discharge for battery operation, and designing better thermal management systems.

Occupational heat stress and associated productivity loss estimation using the PHS model (ISO 7933): a case study from workplaces in Chennai, India.

PubMed

Lundgren, Karin; Kuklane, Kalev; Venugopal, Vidhya

2014-01-01

Heat stress is a major occupational problem in India that can cause adverse health effects and reduce work productivity. This paper explores this problem and its impacts in selected workplaces, including industrial, service, and agricultural sectors in Chennai, India. Quantitative measurements of heat stress, workload estimations, and clothing testing, and qualitative information on health impacts, productivity loss, etc., were collected. Heat strain and associated impacts on labour productivity between the seasons were assessed using the International Standard ISO 7933:2004, which applies the Predicted Heat Strain (PHS) model. All workplaces surveyed had very high heat exposure in the hot season (Wet Bulb Globe Temperature =29.7), often reaching the international standard safe work values (ISO 7243:1989). Most workers had moderate to high workloads (170-220 W/m2), with some exposed to direct sun. Clothing was found to be problematic, with high insulation values in relation to the heat exposure. Females were found to be more vulnerable because of the extra insulation added from wearing a protective shirt on top of traditional clothing (0.96 clo) while working. When analysing heat strain--in terms of core temperature and dehydration--and associated productivity loss in the PHS model, the parameters showed significant impacts that affected productivity in all workplaces, apart from the laundry facility, especially during the hot season. For example, in the canteen, the core temperature limit of 38°C predicted by the model was reached in only 64 min for women. With the expected increases in temperature due to climate change, additional preventive actions have to be implemented to prevent further productivity losses and adverse health impacts. Overall, this study presented insight into using a thermo-physiological model to estimate productivity loss due to heat exposure in workplaces. This is the first time the PHS model has been used for this purpose. An exploratory

Occupational heat stress and associated productivity loss estimation using the PHS model (ISO 7933): a case study from workplaces in Chennai, India

PubMed Central

Lundgren, Karin; Kuklane, Kalev; Venugopal, Vidhya

2014-01-01

Background Heat stress is a major occupational problem in India that can cause adverse health effects and reduce work productivity. This paper explores this problem and its impacts in selected workplaces, including industrial, service, and agricultural sectors in Chennai, India. Design Quantitative measurements of heat stress, workload estimations, and clothing testing, and qualitative information on health impacts, productivity loss, etc., were collected. Heat strain and associated impacts on labour productivity between the seasons were assessed using the International Standard ISO 7933:2004, which applies the Predicted Heat Strain (PHS) model. Results and conclusions All workplaces surveyed had very high heat exposure in the hot season (Wet Bulb Globe Temperature x¯ =29.7), often reaching the international standard safe work values (ISO 7243:1989). Most workers had moderate to high workloads (170–220 W/m2), with some exposed to direct sun. Clothing was found to be problematic, with high insulation values in relation to the heat exposure. Females were found to be more vulnerable because of the extra insulation added from wearing a protective shirt on top of traditional clothing (0.96 clo) while working. When analysing heat strain – in terms of core temperature and dehydration – and associated productivity loss in the PHS model, the parameters showed significant impacts that affected productivity in all workplaces, apart from the laundry facility, especially during the hot season. For example, in the canteen, the core temperature limit of 38°C predicted by the model was reached in only 64 min for women. With the expected increases in temperature due to climate change, additional preventive actions have to be implemented to prevent further productivity losses and adverse health impacts. Overall, this study presented insight into using a thermo-physiological model to estimate productivity loss due to heat exposure in workplaces. This is the first time the PHS

Artificial Neural Networks-Based Software for Measuring Heat Collection Rate and Heat Loss Coefficient of Water-in-Glass Evacuated Tube Solar Water Heaters.

PubMed

Liu, Zhijian; Liu, Kejun; Li, Hao; Zhang, Xinyu; Jin, Guangya; Cheng, Kewei

2015-01-01

Measurements of heat collection rate and heat loss coefficient are crucial for the evaluation of in service water-in-glass evacuated tube solar water heaters. However, conventional measurement requires expensive detection devices and undergoes a series of complicated procedures. To simplify the measurement and reduce the cost, software based on artificial neural networks for measuring heat collection rate and heat loss coefficient of water-in-glass evacuated tube solar water heaters was developed. Using multilayer feed-forward neural networks with back-propagation algorithm, we developed and tested our program on the basis of 915 measured samples of water-in-glass evacuated tube solar water heaters. This artificial neural networks-based software program automatically obtained accurate heat collection rate and heat loss coefficient using simply "portable test instruments" acquired parameters, including tube length, number of tubes, tube center distance, heat water mass in tank, collector area, angle between tubes and ground and final temperature. Our results show that this software (on both personal computer and Android platforms) is efficient and convenient to predict the heat collection rate and heat loss coefficient due to it slow root mean square errors in prediction. The software now can be downloaded from http://t.cn/RLPKF08.

Artificial Neural Networks-Based Software for Measuring Heat Collection Rate and Heat Loss Coefficient of Water-in-Glass Evacuated Tube Solar Water Heaters

PubMed Central

Liu, Zhijian; Liu, Kejun; Li, Hao; Zhang, Xinyu; Jin, Guangya; Cheng, Kewei

2015-01-01

Measurements of heat collection rate and heat loss coefficient are crucial for the evaluation of in service water-in-glass evacuated tube solar water heaters. However, conventional measurement requires expensive detection devices and undergoes a series of complicated procedures. To simplify the measurement and reduce the cost, software based on artificial neural networks for measuring heat collection rate and heat loss coefficient of water-in-glass evacuated tube solar water heaters was developed. Using multilayer feed-forward neural networks with back-propagation algorithm, we developed and tested our program on the basis of 915measuredsamples of water-in-glass evacuated tube solar water heaters. This artificial neural networks-based software program automatically obtained accurate heat collection rateand heat loss coefficient using simply "portable test instruments" acquired parameters, including tube length, number of tubes, tube center distance, heat water mass in tank, collector area, angle between tubes and ground and final temperature. Our results show that this software (on both personal computer and Android platforms) is efficient and convenient to predict the heat collection rate and heat loss coefficient due to it slow root mean square errors in prediction. The software now can be downloaded from http://t.cn/RLPKF08. PMID:26624613

Head insulation and heat loss in naked and clothed newborns using a thermal mannequin.

PubMed

Elabbassi, Elmountacer Billah; Chardon, Karen; Bach, Véronique; Telliez, Frédéric; Delanaud, Stéphane; Libert, Jean-Pierre

2002-06-01

In newborns, large amounts of heat are lost from the head, due to its high skin surface area. Insulating the head (for example, with a hat or bonnet) can be a simple and effective method of reducing dry heat loss. In the present study, we evaluated the safety aspects of insulating the head of low-birth-weight naked or clothed newborns by using a heated mannequin that simulates a low-birth-weight newborn. Experimental conditions (comprising a nude and three clothed setups) were performed in a closed incubator at three different air temperatures (29 degrees C, 32 degrees C, and 34 degrees C) and with and without the head being covered with a bonnet in each case, i.e., 24 experimental conditions in all. The study shows that added clothing elements and insulating the head decreases the total heat loss of the mannequin as a whole. As regards the dry heat exchange from the head, wearing a bonnet decreases the local heat loss by an average of 18.9% in all clothed and thermal conditions. This phenomenon could be at the origin of brain overheating in heavily dressed newborns, when unrestricted heat loss is limited to the face only. Our results suggest that--apart from accidental hypothermia-in order to achieve thermal equilibrium of the body, it is preferable to leave the head unprotected and to increase the level of clothing insulation over the rest of the body.

Enhanced O2 Loss at Mars Due to an Ambipolar Electric Field from Electron Heating

NASA Technical Reports Server (NTRS)

Ergun, R. E.; Andersson, L. A.; Fowler, C. M.; Woodson, A. K.; Weber, T. D.; Delory, G. T.; Andrews, D. J.; Eriksson, A. I.; Mcenulty, T.; Morooka, M. W.;

Extreme learning machine: a new alternative for measuring heat collection rate and heat loss coefficient of water-in-glass evacuated tube solar water heaters.

PubMed

Liu, Zhijian; Li, Hao; Tang, Xindong; Zhang, Xinyu; Lin, Fan; Cheng, Kewei

2016-01-01

Heat collection rate and heat loss coefficient are crucial indicators for the evaluation of in service water-in-glass evacuated tube solar water heaters. However, the direct determination requires complex detection devices and a series of standard experiments, wasting too much time and manpower. To address this problem, we previously used artificial neural networks and support vector machine to develop precise knowledge-based models for predicting the heat collection rates and heat loss coefficients of water-in-glass evacuated tube solar water heaters, setting the properties measured by "portable test instruments" as the independent variables. A robust software for determination was also developed. However, in previous results, the prediction accuracy of heat loss coefficients can still be improved compared to those of heat collection rates. Also, in practical applications, even a small reduction in root mean square errors (RMSEs) can sometimes significantly improve the evaluation and business processes. As a further study, in this short report, we show that using a novel and fast machine learning algorithm-extreme learning machine can generate better predicted results for heat loss coefficient, which reduces the average RMSEs to 0.67 in testing.

A model for allometric scaling of mammalian metabolism with ambient heat loss.

PubMed

Kwak, Ho Sang; Im, Hong G; Shim, Eun Bo

2016-03-01

Allometric scaling, which represents the dependence of biological traits or processes on body size, is a long-standing subject in biological science. However, there has been no study to consider heat loss to the ambient and an insulation layer representing mammalian skin and fur for the derivation of the scaling law of metabolism. A simple heat transfer model is proposed to analyze the allometry of mammalian metabolism. The present model extends existing studies by incorporating various external heat transfer parameters and additional insulation layers. The model equations were solved numerically and by an analytic heat balance approach. A general observation is that the present heat transfer model predicted the 2/3 surface scaling law, which is primarily attributed to the dependence of the surface area on the body mass. External heat transfer effects introduced deviations in the scaling law, mainly due to natural convection heat transfer, which becomes more prominent at smaller mass. These deviations resulted in a slight modification of the scaling exponent to a value < 2/3. The finding that additional radiative heat loss and the consideration of an outer insulation fur layer attenuate these deviation effects and render the scaling law closer to 2/3 provides in silico evidence for a functional impact of heat transfer mode on the allometric scaling law in mammalian metabolism.

Alterations in heat loss and heat production mechanisms in rat exposed to hypergravic fields

NASA Technical Reports Server (NTRS)

Horowitz, J. M.; Horwitz, B. A.; Oyama, J.

1982-01-01

A review of studies investigating the thermal response of rats exposed to hypergravic fields well below maximum tolerance levels is presented. It is concluded that several lines of evidence indicate that the neural switching network for temperature regulation and cardiovascular channeling of blood flow is transiently affected during the first hour a rat is exposed to hypergravity. Moreover, even after one hour of exposure, when the core temperature has fallen several degrees, shivering and nonshivering thermogenesis are not fully activated. Only after prolonged exposure to hypergravic fields do heat production mechanisms recover sufficiently to bring the core temperature back to a normal level. Thus, the data indicate a more rapid recovery of effector mechanisms for heat loss than for heat production.

Quantitative Global Heat Transfer in a Mach-6 Quiet Tunnel

NASA Technical Reports Server (NTRS)

Sullivan, John P.; Schneider, Steven P.; Liu, Tianshu; Rubal, Justin; Ward, Chris; Dussling, Joseph; Rice, Cody; Foley, Ryan; Cai, Zeimin; Wang, Bo;

Enhanced economic connectivity to foster heat stress-related losses.

PubMed

Wenz, Leonie; Levermann, Anders

2016-06-01

Assessing global impacts of unexpected meteorological events in an increasingly connected world economy is important for estimating the costs of climate change. We show that since the beginning of the 21st century, the structural evolution of the global supply network has been such as to foster an increase of climate-related production losses. We compute first- and higher-order losses from heat stress-induced reductions in productivity under changing economic and climatic conditions between 1991 and 2011. Since 2001, the economic connectivity has augmented in such a way as to facilitate the cascading of production loss. The influence of this structural change has dominated over the effect of the comparably weak climate warming during this decade. Thus, particularly under future warming, the intensification of international trade has the potential to amplify climate losses if no adaptation measures are taken.

Enhanced economic connectivity to foster heat stress–related losses

PubMed Central

Wenz, Leonie; Levermann, Anders

2016-01-01

Assessing global impacts of unexpected meteorological events in an increasingly connected world economy is important for estimating the costs of climate change. We show that since the beginning of the 21st century, the structural evolution of the global supply network has been such as to foster an increase of climate-related production losses. We compute first- and higher-order losses from heat stress–induced reductions in productivity under changing economic and climatic conditions between 1991 and 2011. Since 2001, the economic connectivity has augmented in such a way as to facilitate the cascading of production loss. The influence of this structural change has dominated over the effect of the comparably weak climate warming during this decade. Thus, particularly under future warming, the intensification of international trade has the potential to amplify climate losses if no adaptation measures are taken. PMID:27386555

Combined heat transfer and kinetic models to predict cooking loss during heat treatment of beef meat.

PubMed

Kondjoyan, Alain; Oillic, Samuel; Portanguen, Stéphane; Gros, Jean-Bernard

2013-10-01

A heat transfer model was used to simulate the temperature in 3 dimensions inside the meat. This model was combined with a first-order kinetic models to predict cooking losses. Identification of the parameters of the kinetic models and first validations were performed in a water bath. Afterwards, the performance of the combined model was determined in a fan-assisted oven under different air/steam conditions. Accurate knowledge of the heat transfer coefficient values and consideration of the retraction of the meat pieces are needed for the prediction of meat temperature. This is important since the temperature at the center of the product is often used to determine the cooking time. The combined model was also able to predict cooking losses from meat pieces of different sizes and subjected to different air/steam conditions. It was found that under the studied conditions, most of the water loss comes from the juice expelled by protein denaturation and contraction and not from evaporation. Copyright © 2013 Elsevier Ltd. All rights reserved.

The thermoregulatory function of the human hand: How do palm and digit proportions affect heat loss?

PubMed

Payne, Stephanie; Macintosh, Alison; Stock, Jay

2018-03-30

The current study assessed whether ecogeographical patterns seen in hand proportions correlate with heat loss directly. Using a brief severe cold immersion experiment on the hand, the influence of hand and digit dimensions on heat loss was evaluated. A sample of 113 living individuals were tested. Two-dimensional and three-dimensional scanning techniques were used to assess hand and digit dimensions. Thermal imaging analysis was used to quantify heat loss during a 3-min ice-water immersion of the hands. When body size was accounted for, hand width and digit length relative to total hand length were significant predictors of heat loss from the hand. The current study provides empirical evidence to support the link between thermodynamic principles relating to surface area-to-volume ratio, and ecogeographical patterns associated with temperature. © 2018 Wiley Periodicals, Inc.

Effect of Wind Flow on Convective Heat Losses from Scheffler Solar Concentrator Receivers

NASA Astrophysics Data System (ADS)

Nene, Anita Arvind; Ramachandran, S.; Suyambazhahan, S.

2018-05-01

Receiver is an important element of solar concentrator system. In a Scheffler concentrator, solar rays get concentrated at focus of parabolic dish. While radiation losses are more predictable and calculable since strongly related to receiver temperature, convective looses are difficult to estimate in view of additional factors such as wind flow direction, speed, receiver geometry, prior to current work. Experimental investigation was carried out on two geometries of receiver namely cylindrical and conical with 2.7 m2 Scheffler to find optimum condition of tilt to provide best efficiency. Experimental results showed that as compared to cylindrical receiver, conical receiver gave maximum efficiency at 45° tilt angle. However effect of additional factors like wind speed, wind direction on especially convective losses could not be separately seen. The current work was undertaken to investigate further the same two geometries using computation fluid dynamics using FLUENT to compute convective losses considering all variables such at tilt angle of receiver, wind velocity and wind direction. For cylindrical receiver, directional heat transfer coefficient (HTC) is remarkably high to tilt condition meaning this geometry is critical to tilt leading to higher convective heat losses. For conical receiver, directional average HTC is remarkably less to tilt condition leading to lower convective heat loss.

Heat Loss Experiments: Teach Energy Savings with Cardboard "House"

ERIC Educational Resources Information Center

Roman, Harry T.

2011-01-01

Using two cardboard boxes, a light bulb socket, light bulbs of varying wattage, a thermometer, and some insulation, students can learn some interesting lessons about how heat loss occurs in homes. This article describes practical experiments that work well on units related to energy, sustainable energy, renewables, engineering, and construction.…

Pressure losses and heat transfer in non-circular channels with hydraulically smooth walls

NASA Technical Reports Server (NTRS)

Malak, J.

1982-01-01

The influence of channel geometry on pressure losses and heat transfer in noncircular channels with hydraulically smooth walls was studied. As a basic assumption for the description of this influence, integral geometrical criteria, selected according to experimental experience, were introduced. Using these geometrical criteria, a large set of experimental data for pressure losses and heat transfer in circular and annular channels with longitudinal fins was evaluated. In this way it as empirically proved that the criteria described channel geometry fairly well.

Determining heat loss into the environment based on comprehensive investigation of boiler performance characteristics

NASA Astrophysics Data System (ADS)

Lyubov, V. K.; Malygin, P. V.; Popov, A. N.; Popova, E. I.

2015-08-01

A refined procedure for determining heat loss into the environment from heat-generating installations is presented that takes into account the state of their lining and heat insulation quality. The fraction of radiative component in the total amount of heat loss through the outer surfaces is determined. The results from experimental investigations of the thermal engineering and environmental performance characteristics of a foreign hot-water boiler in firing wood pellets are presented. A conclusion is drawn about the possibility of using such hot-water boilers for supplying heat to low-rise buildings, especially for the conditions of the North-Arctic region. The results from a thermal engineering investigation of wood pellets and furnace residue carried out on installations of a thermal analysis laboratory are presented together with the grain-size composition of fuel and indicators characterizing the mechanical strength of wood pellets. The velocity fields, flue gas flow rates, and soot particle concentrations are determined using the external filtration methods, and the composition of combustion products is investigated using a gas analyzer. The graphs of variation with time of boiler external surface temperature from the moment of achieving the nominal mode of operation and heat loss into the environment for stationary boilers are presented.

Quantitative method for measuring heat flux emitted from a cryogenic object

DOEpatents

Duncan, Robert V.

1993-01-01

The present invention is a quantitative method for measuring the total heat flux, and of deriving the total power dissipation, of a heat-fluxing object which includes the steps of placing an electrical noise-emitting heat-fluxing object in a liquid helium bath and measuring the superfluid transition temperature of the bath. The temperature of the liquid helium bath is thereafter reduced until some measurable parameter, such as the electrical noise, exhibited by the heat-fluxing object or a temperature-dependent resistive thin film in intimate contact with the heat-fluxing object, becomes greatly reduced. The temperature of the liquid helum bath is measured at this point. The difference between the superfluid transition temperature of the liquid helium bath surrounding the heat-fluxing object, and the temperature of the liquid helium bath when the electrical noise emitted by the heat-fluxing object becomes greatly reduced, is determined. The total heat flux from the heat-fluxing object is determined as a function of this difference between these temperatures. In certain applications, the technique can be used to optimize thermal design parameters of cryogenic electronics, for example, Josephson junction and infra-red sensing devices.

Quantitative method for measuring heat flux emitted from a cryogenic object

DOEpatents

Duncan, R.V.

1993-03-16

The present invention is a quantitative method for measuring the total heat flux, and of deriving the total power dissipation, of a heat-fluxing object which includes the steps of placing an electrical noise-emitting heat-fluxing object in a liquid helium bath and measuring the superfluid transition temperature of the bath. The temperature of the liquid helium bath is thereafter reduced until some measurable parameter, such as the electrical noise, exhibited by the heat-fluxing object or a temperature-dependent resistive thin film in intimate contact with the heat-fluxing object, becomes greatly reduced. The temperature of the liquid helum bath is measured at this point. The difference between the superfluid transition temperature of the liquid helium bath surrounding the heat-fluxing object, and the temperature of the liquid helium bath when the electrical noise emitted by the heat-fluxing object becomes greatly reduced, is determined. The total heat flux from the heat-fluxing object is determined as a function of this difference between these temperatures. In certain applications, the technique can be used to optimize thermal design parameters of cryogenic electronics, for example, Josephson junction and infrared sensing devices.

Influence of heat losses on nonlinear fingering dynamics of exothermic autocatalytic fronts

NASA Astrophysics Data System (ADS)

D'Hernoncourt, J.; De Wit, A.

2010-06-01

Across traveling exothermic autocatalytic fronts, a density jump can be observed due to changes in composition and temperature. These density changes are prone to induce buoyancy-driven convection around the front when the propagation takes place in absence of gel within the gravity field. Most recent experiments devoted to studying such reaction-diffusion-convection dynamics are performed in Hele-Shaw cells, two glass plates separated by a thin gap width and filled by the chemical solutions. We investigate here the influence of heat losses through the walls of such cells on the nonlinear fingering dynamics of exothermic autocatalytic fronts propagating in vertical Hele-Shaw cells. We show that these heat losses increase tip splittings and modify the properties of the flow field. A comparison of the differences between the dynamics in reactors with respectively insulating and conducting walls is performed as a function of the Lewis number Le, the Newton cooling coefficient α quantifying the amplitude of heat losses and the width of the system. We find that tip splitting is enhanced for intermediate values of α while coarsening towards one single finger dominates for insulated systems or large values of α leading to situations equivalent to isothermal ones.

Surface temperature/heat transfer measurement using a quantitative phosphor thermography system

NASA Technical Reports Server (NTRS)

Buck, G. M.

1991-01-01

A relative-intensity phosphor thermography technique developed for surface heating studies in hypersonic wind tunnels is described. A direct relationship between relative emission intensity and phosphor temperature is used for quantitative surface temperature measurements in time. The technique provides global surface temperature-time histories using a 3-CCD (Charge Coupled Device) video camera and digital recording system. A current history of technique development at Langley is discussed. Latest developments include a phosphor mixture for a greater range of temperature sensitivity and use of castable ceramics for inexpensive test models. A method of calculating surface heat-transfer from thermal image data in blowdown wind tunnels is included in an appendix, with an analysis of material thermal heat-transfer properties. Results from tests in the Langley 31-Inch Mach 10 Tunnel are presented for a ceramic orbiter configuration and a four-inch diameter hemisphere model. Data include windward heating for bow-shock/wing-shock interactions on the orbiter wing surface, and a comparison with prediction for hemisphere heating distribution.

Comparison of IR thermography and thermocouple measurement of heat loss from rabbit pinna.

PubMed

Mohler, F S; Heath, J E

1988-02-01

The temperature of the pinnae of male New Zealand White rabbits was measured by use of infrared thermography. At ambient temperatures of 15, 20, and 25 degrees C, the average pinna temperatures were 23.0, 28.7, and 36.2 degrees C, respectively. From these temperatures, average heat loss from the total pinna surface area was calculated to be 2.8, 3.3, and 4.4 W, respectively. Preoptic temperature changes also affect the vasomotor state of the rabbit. At an ambient temperature of 20 degrees C, cooling the preoptic area of the rabbit by approximately 1 degree C resulted in an average pinna temperature of 26.5 degrees C and a heat loss of 2.4 W. Heating the preoptic area by approximately 1 degree C resulted in an average pinna temperature of 33.5 degrees C and a heat loss of 5.4 W. Finally, pinna temperatures were measured by use of a thermocouple and infrared thermography simultaneously. When the pinnae were vasodilated, the thermocouple measurements were consistently higher than the pinna surface temperatures measured thermographically. When the pinnae were vasoconstricted, the thermocouple measurements were consistently lower than the pinna surface temperatures measured thermographically. The discrepancy between the two methods of measurement is discussed.

Magnetic flux and heat losses by diffusive, advective, and Nernst effects in MagLIF-like plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Velikovich, A. L., E-mail: sasha.velikovich@nrl.navy.mil; Giuliani, J. L., E-mail: sasha.velikovich@nrl.navy.mil; Zalesak, S. T.

2014-12-15

The MagLIF approach to inertial confinement fusion involves subsonic/isobaric compression and heating of a DT plasma with frozen-in magnetic flux by a heavy cylindrical liner. The losses of heat and magnetic flux from the plasma to the liner are thereby determined by plasma advection and gradient-driven transport processes, such as thermal conductivity, magnetic field diffusion and thermomagnetic effects. Theoretical analysis based on obtaining exact self-similar solutions of the classical collisional Braginskii's plasma transport equations in one dimension demonstrates that the heat loss from the hot plasma to the cold liner is dominated by the transverse heat conduction and advection, andmore » the corresponding loss of magnetic flux is dominated by advection and the Nernst effect. For a large electron Hall parameter ω{sub e}τ{sub e} effective diffusion coefficients determining the losses of heat and magnetic flux are both shown to decrease with ω{sub e}τ{sub e} as does the Bohm diffusion coefficient, which is commonly associated with low collisionality and two-dimensional transport. This family of exact solutions can be used for verification of codes that model the MagLIF plasma dynamics.« less

The study of the mobile compressor unit heat losses recovery system waste heat exchanger thermal insulation types influence on the operational efficiency

NASA Astrophysics Data System (ADS)

Yusha, V. L.; Chernov, G. I.; Kalashnikov, A. M.

2017-08-01

The paper examines the mobile compressor unit (MCU) heat losses recovery system waste heat exchanger prototype external thermal insulation types influence on the operational efficiency. The study is conducted by means of the numerical method through the modellingof the heat exchange processes carried out in the waste heat exchanger in ANSUS. Thermaflex, mineral wool, penofol, water and air were applied as the heat exchanger external insulation. The study results showed the waste heat exchanger external thermal insulationexistence or absence to have a significant impact on the heat exchanger operational efficiency.

Heat Loss Testing of Schott's 2008 PTR70 Parabolic Trough Receiver

DOE Office of Scientific and Technical Information (OSTI.GOV)

Burkholder, Frank; Kutscher, Chuck

2009-05-01

Two Schott 2008 model year PTR70 HCEs were tested on NREL's heat loss test stand from 100 - 500 deg C in 50 deg C increments. Absorber emittance was determined from the laboratory testing so that the performance of the HCEs could be modeled in a parabolic trough collector. Collector/HCE simulation results for many different field operation conditions were used to create heat loss correlationcoefficients for Excelergy and SAM. SAM estimates that the decreased emittance of the 2008 PTR70 will decrease the LCOE for parabolic trough power plants by 0.5 cents/kWh and increase the electricity generated by 5% relative tomore » previous PTR70s. These conclusions assume that the 2008 PTR70 is supplied at the same cost and with the same optical performance as earlier PTR70 models.« less

Body fatness, body core temperature, and heat loss during moderate-intensity exercise.

PubMed

Limbaugh, Jayme D; Wimer, Gregory S; Long, Lynn H; Baird, William H

2013-11-01

This study examined the influence of body fatness on body core temperature and heat loss responses during moderate-intensity exercise. Nine men with lower body fat and eight men with higher body fat, matched for aerobic fitness, completed 1 h of recumbent cycling at the same absolute intensity in a warm environment (30 degrees C, 40% RH). Percent body fat was measured by hydrostatic weighing, using oxygen dilution to determine residual volume. Esophageal temperature (T(es)), mean skin temperature (T(sk)), and local sweat rate (m(sw)) were measured at rest and continuously during exercise while forearm blood flow (FBF) was measured at rest and every 10 min during exercise. The lower body fat and higher body fat groups were successfully matched for aerobic fitness, removing the influence of body fatness, given that V/O2(peak) was 50.72 +/- 7.34 and 50.43 +/- 5.01 ml x kg LBM(-1) x min(-1), respectively. When compared to lower body fat individuals, % body fat, body surface area (A(D)), and body mass were higher and A(D)/ mass was lower in higher body fat individuals. T(es), T(sk), FBF, m(sw), and the slope of m(sw):T(es) were not different between groups. Metabolic heat production was similar between the lower body fat (299.7 +/- 40.5 W x m(-2)) and higher body fat (288.1 +/- 30.6 W x m(-2)) subjects, respectively. Dry and evaporative heat loss, as well as heat storage during exercise, were not different between groups. These data suggest that there is no effect of body fatness on body core temperature or heat loss responses during moderate-intensity exercise in a warm environment.

Oscillating-flow loss test results in rectangular heat exchanger passages

NASA Technical Reports Server (NTRS)

Wood, J. Gary

1991-01-01

Test results of oscillating flow losses in rectangular heat exchanger passages of various aspect ratios are given. This work was performed in support of the design of a free-piston Stirling engine (FPSE) for a dynamic space power conversion system. Oscillating flow loss testing was performed using an oscillating flow rig, which was based on a variable stroke and variable frequency linear drive motor. Tests were run over a range of oscillating flow parameters encompassing the flow regimes of the proposed engine design. Test results are presented in both tabular and graphical form and are compared against analytical predictions.

Heat loss analysis-based design of a 12 MW wind power generator module having an HTS flux pump exciter

NASA Astrophysics Data System (ADS)

Sung, Hae-Jin; Go, Byeong-Soo; Jiang, Zhenan; Park, Minwon; Yu, In-Keun

2016-11-01

The development of an effective high-temperature superconducting (HTS) generator is currently a research focus; however, the reduction of heat loss of a large-scale HTS generator is a challenge. This study deals with a heat loss analysis-based design of a 12 MW wind power generator module having an HTS flux pump exciter. The generator module consists of an HTS rotor of the generator and an HTS flux pump exciter. The specifications of the module were described, and the detailed configuration of the module was illustrated. For the heat loss analysis of the module, the excitation loss of the flux pump exciter, eddy current loss of all of the structures in the module, radiation loss, and conduction loss of an HTS coil supporter were assessed using a 3D finite elements method program. In the case of the conduction loss, different types of the supporters were compared to find out the supporter of the lowest conduction loss in the module. The heat loss analysis results of the module were reflected in the design of the generator module and discussed in detail. The results will be applied to the design of large-scale superconducting generators for wind turbines including a cooling system.

An Analytical Investigation of the Heat Losses from a U.S. Navy K-Type Airship

NASA Technical Reports Server (NTRS)

Hillendahl, Wesley H.; George, Ralph E.

1946-01-01

The heat losses from the envelope surface of a U.S. Navy K-type airship are evaluated to determine if the use of heat is a feasible means of preventing ice and snow accumulations on lighter-than-air craft during flight and when moored uncovered. Consideration is given to heat losses in clear air (no liquid water present in the atmosphere) and in probable conditions of icing and snow. The results of the analysis indicate that the amount of heat required in flight to raise the surface temperature of the entire envelope to the extent considered adequate for ice protection, based on experience with tests of heavier-than-air craft, is very large. Existing types of heating equipment which could be used to supply this quantity of heat would probably be too bulky and heavy to provide a practical flight installation. The heat requirements to provide protection for the nose and stern regions in assumed mild to moderate icing conditions appear to be within the range of the capacity of current types of heating equipment suitable for flight use. The amount of heat necessary to prevent snow accumulations on the upper surface of the airship envelope when moored uncovered under all conditions appear to be excessive for the heating equipment presently available for flight use, but could possibly be achieved with auxiliary ground heating equipment.

On the Influence of a Fuel Side Heat-Loss (Soot) Layer on a Planar Diffusion Flame

NASA Technical Reports Server (NTRS)

Wichman, Indrek S.

1994-01-01

A model of the response of a diffusion flame (DF) to an adjacent heat loss or 'soot' layer on the fuel side is investigated. The thermal influence of the 'soot' or heat-loss layer on the DF occurs through the enthalpy sink it creates. A sink distribution in mixture-fraction space is employed to examine possible DF extinction. It is found that (1) the enthalpy sink (or soot layer) must touch the DF for radiation-induced quenching to occur; and (2) for fuel-rich conditions extinction is possible only for a progressively narrower range of values ot the characteristic heat-loss parameter, N(sub R)(Delta Z(sub R)) Various interpretations ot the model are discussed. An attempt is made to place this work into the context created by previous experimental and computational studies.

Quantitative trait loci identified for blood chemistry components of an advanced intercross line of chickens under heat stress.

PubMed

Van Goor, Angelica; Ashwell, Christopher M; Persia, Michael E; Rothschild, Max F; Schmidt, Carl J; Lamont, Susan J

2016-04-14

Heat stress in poultry results in considerable economic losses and is a concern for both animal health and welfare. Physiological changes occur during periods of heat stress, including changes in blood chemistry components. A highly advanced intercross line, created from a broiler (heat susceptible) by Fayoumi (heat resistant) cross, was exposed to daily heat cycles for seven days starting at 22 days of age. Blood components measured pre-heat treatment and on the seventh day of heat treatment included pH, pCO2, pO2, base excess, HCO3, TCO2, K, Na, ionized Ca, hematocrit, hemoglobin, sO2, and glucose. A genome-wide association study (GWAS) for these traits and their calculated changes was conducted to identify quantitative trait loci (QTL) using a 600 K SNP panel. There were significant increases in pH, base excess, HCO3, TCO2, ionized Ca, hematocrit, hemoglobin, and sO2, and significant decreases in pCO2 and glucose after 7 days of heat treatment. Heritabilities ranged from 0.01-0.21 for pre-heat measurements, 0.01-0.23 for measurements taken during heat, and 0.00-0.10 for the calculated change due to heat treatment. All blood components were highly correlated within measurement days, but not correlated between measurement days. The GWAS revealed 61 QTL for all traits, located on GGA (Gallus gallus chromosome) 1, 3, 6, 9, 10, 12-14, 17, 18, 21-28, and Z. A functional analysis of the genes in these QTL regions identified the Angiopoietin pathway as significant. The QTL that co-localized for three or more traits were on GGA10, 22, 26, 28, and Z and revealed candidate genes for birds' response to heat stress. The results of this study contribute to our knowledge of levels and heritabilities of several blood components of chickens under thermoneutral and heat stress conditions. Most components responded to heat treatment. Mapped QTL may serve as markers for genomic selection to enhance heat tolerance in poultry. The Angiopoietin pathway is likely involved in the

QUANTITATION OF MENSTRUAL BLOOD LOSS: A RADIOACTIVE METHOD UTILIZING A COUNTING DOME

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tauxe, W.N.

A description has been given of a simple, accurate tech nique for the quantitation of menstrual blood loss, involving the determination of a three- dimensional isosensitivity curve and the fashioning of a lucite dome with cover to fit these specifications. Ten normal subjects lost no more than 50 ml each per menstrual period. (auth)

Latent heat loss and sweat gland histology of male goats in an equatorial semi-arid environment

NASA Astrophysics Data System (ADS)

de Melo Costa, Cíntia Carol; Maia, Alex Sandro Campos; Neto, José Domingues Fontenele; Oliveira, Steffan Edward Octávio; de Queiroz, João Paulo Araújo Fernandes

2014-03-01

The objective of this work was to quantify the heat loss by cutaneous evaporation of goats in an equatorial semi-arid environment. The latent heat loss from the body surfaces of these ten undefined breed goats was measured using a ventilated capsule in sun and shade and in the three body regions (neck, flank and hindquarters). Skin samples from these three regions were histologically analyzed to relate the quantity of sweat glands, the area of sweat glands and the epithelium thickness of each of these regions to the heat loss by cutaneous evaporation of the examined goats. The epithelium thickness that was measured varied significantly for body regions with different quantities and areas of sweat glands ( P < 0.01). Among the body regions that were examined, the samples from the neck demonstrated the highest epithelium thickness (16.23 ± 0.13 μm). However, the samples of sweat glands from the flank had the biggest area (43330.51 ± 778.71 μm2) and quantity per square centimeter (390 ± 9 cm-2). After the animals were exposed to sun, the flanks lost the greatest amount of heat by cutaneous evaporation (73.03 ± 1.75 W m-2) and possessed the highest surface temperatures (39.47 ± 0.18 °C). The histological characteristics may have influenced the heat loss by cutaneous evaporation that was observed in the flank region after the animals were exposed to sun.

Aging impairs heat loss, but when does it matter?

PubMed Central

Stapleton, Jill M.; Poirier, Martin P.; Flouris, Andreas D.; Boulay, Pierre; Sigal, Ronald J.; Malcolm, Janine

2014-01-01

Aging is associated with an attenuated physiological ability to dissipate heat. However, it remains unclear if age-related impairments in heat dissipation only occur above a certain level of heat stress and whether this response is altered by aerobic fitness. Therefore, we examined changes in whole body evaporative heat loss (HE) as determined using whole body direct calorimetry in young (n = 10; 21 ± 1 yr), untrained middle-aged (n = 10; 48 ± 5 yr), and older (n = 10; 65 ± 3 yr) males matched for body surface area. We also studied a group of trained middle-aged males (n = 10; 49 ± 5 yr) matched for body surface area with all groups and for aerobic fitness with the young group. Participants performed intermittent aerobic exercise (30-min exercise bouts separated by 15-min rest) in the heat (40°C and 15% relative humidity) at progressively greater fixed rates of heat production equal to 300 (Ex1), 400 (Ex2), and 500 (Ex3) W. Results showed that HE was significantly lower in middle-aged untrained (Ex2: 426 ± 34; and Ex3: 497 ± 17 W) and older (Ex2: 424 ± 38; and Ex3: 485 ± 44 W) compared with young (Ex2: 472 ± 42; and Ex3: 558 ± 51 W) and middle-aged trained (474 ± 21; Ex3: 552 ± 23 W) males at the end of Ex2 and Ex3 (P < 0.05). No differences among groups were observed during recovery. We conclude that impairments in HE in older and middle-aged untrained males occur at exercise-induced heat loads of ≥400 W when performed in a hot environment. These impairments in untrained middle-aged males can be minimized through regular aerobic exercise training. PMID:25505030

Fast quantitative optical detection of heat dissipation by surface plasmon polaritons.

PubMed

Möller, Thomas B; Ganser, Andreas; Kratt, Martina; Dickreuter, Simon; Waitz, Reimar; Scheer, Elke; Boneberg, Johannes; Leiderer, Paul

2018-06-13

Heat management at the nanoscale is an issue of increasing importance. In optoelectronic devices the transport and decay of plasmons contribute to the dissipation of heat. By comparison of experimental data and simulations we demonstrate that it is possible to gain quantitative information about excitation, propagation and decay of surface plasmon polaritons (SPPs) in a thin gold stripe supported by a silicon membrane. The temperature-dependent optical transmissivity of the membrane is used to determine the temperature distribution around the metal stripe with high spatial and temporal resolution. This method is complementary to techniques where the propagation of SPPs is monitored optically, and provides additional information which is not readily accessible by other means. In particular, we demonstrate that the thermal conductivity of the membrane can also be derived from our analysis. The results presented here show the high potential of this tool for heat management studies in nanoscale devices.

Intestinal blood loss during cow milk feeding in older infants: quantitative measurements.

PubMed

Jiang, T; Jeter, J M; Nelson, S E; Ziegler, E E

2000-07-01

To determine the response, in terms of fecal hemoglobin excretion and clinical symptoms, of normal 9 1/2-month-old infants to being fed cow milk. Longitudinal (before-after) trial in which each infant was fed formula for 1 month (baseline) followed by 3 months during which cow milk was fed. Healthy infants living in Iowa City, Iowa, a town with a population of about 60,000. Hemoglobin concentration in spot stools, 96-hour quantitative fecal hemoglobin excretion, stool characteristics, feeding-related behaviors, and iron nutritional status. Fecal hemoglobin concentration during formula feeding (baseline) was higher than previously observed in younger infants. Nine of 31 infants responded to cow milk feeding with increased fecal hemoglobin concentration. Fecal hemoglobin concentration (mean +/- SD) of the 9 responders rose from 1,395 +/- 856 microg/g of dry stool (baseline) to 2,711 +/- 1,732 microg/g of dry stool (P=.01). The response rate (29%) was similar to that in younger infants, but the intensity of the response was much less. Quantitative hemoglobin excretion was in general agreement with estimates based on spot stool hemoglobin concentrations. Cow milk feeding was not associated with recognizable changes in stool characteristics, nor were there clinical signs related to fecal blood loss. Iron status was similar, except that after 3 months of cow milk feeding responders showed lower (P= .047) ferritin concentrations than nonresponders. Cow milk-induced blood loss is present in 9 1/2-month-old infants but is of such low intensity that its clinical significance seems questionable. Nevertheless, infants without cow milk-induced blood loss were in better iron nutritional status than infants who showed blood loss.

Comparison of Various Supersonic Turbine Tip Designs to Minimize Aerodynamic Loss and Tip Heating

NASA Technical Reports Server (NTRS)

Shyam, Vikram; Ameri, Ali

2012-01-01

The rotor tips of axial turbines experience high heat flux and are the cause of aerodynamic losses due to tip clearance flows, and in the case of supersonic tips, shocks. As stage loadings increase, the flow in the tip gap approaches and exceeds sonic conditions. This introduces effects such as shock-boundary layer interactions and choked flow that are not observed for subsonic tip flows that have been studied extensively in literature. This work simulates the tip clearance flow for a flat tip, a diverging tip gap and several contoured tips to assess the possibility of minimizing tip heat flux while maintaining a constant massflow from the pressure side to the suction side of the rotor, through the tip clearance. The Computational Fluid Dynamics (CFD) code GlennHT was used for the simulations. Due to the strong favorable pressure gradients the simulations assumed laminar conditions in the tip gap. The nominal tip gap width to height ratio for this study is 6.0. The Reynolds number of the flow is 2.4 x 10(exp 5) based on nominal tip width and exit velocity. A wavy wall design was found to reduce heat flux by 5 percent but suffered from an additional 6 percent in aerodynamic loss coefficient. Conventional tip recesses are found to perform far worse than a flat tip due to severe shock heating. Overall, the baseline flat tip was the second best performer. A diverging converging tip gap with a hole was found to be the best choice. Average tip heat flux was reduced by 37 percent and aerodynamic losses were cut by over 6 percent.

Turbomachinery Heat Transfer and Loss Modeling for 3D Navier-Stokes Codes

NASA Technical Reports Server (NTRS)

DeWitt, Kenneth; Ameri, Ali

2005-01-01

This report's contents focus on making use of NASA Glenn on-site computational facilities,to develop, validate, and apply models for use in advanced 3D Navier-Stokes Computational Fluid Dynamics (CFD) codes to enhance the capability to compute heat transfer and losses in turbomachiney.

Quantitative study of the correlation between cerebellar retraction factors and hearing loss following microvascular decompression for hemifacial spasm.

PubMed

Li, Ning; Zhao, Wei-Guo; Pu, Chun-Hua; Yang, Wen-Lei

2018-01-01

This prospective study quantitatively measured the cerebellar retraction factors, including retraction distance, depth and duration, and evaluated their potential relationship to the development of hearing loss after microvascular decompression (MVD) for hemifacial spasm (HFS). One hundred ten patients with primary HFS who underwent MVD in our department were included into this study. The cerebellar retraction factors were quantitatively measured on preoperative MR and timed during MVD. Associations of cerebellar retraction and other factors to postoperative hearing loss were analyzed. Eleven (10%) patients developed hearing loss after MVD. Compared with the group without hearing loss, the cerebellar retraction distance, depth and duration of the group with hearing loss were significantly greater (p < 0.05). Multivariate regression analysis showed that greater cerebellar retraction depth and longer retraction duration were significantly associated with a higher incidence of postoperative hearing impairment (p < 0.05). This study strongly suggested a correlation between the cerebellar retraction factors, especially retraction depth and duration, and possibility of hearing loss following MVD for HFS.

Heat-curved girders : deflections and camber loss during and subsequent to bridge construction.

DOT National Transportation Integrated Search

1982-01-01

The present AASHTO bridge design specifications require that additional camber be built into steel girders that are to be heat curved. The additional camber is provided to allow for subsequent losses due to the dissipation of residual stresses impose...

Radiant heat loss, an unexploited path for heat stress reduction in shaded cattle.

PubMed

Berman, A; Horovitz, T

2012-06-01

Reducing thermal radiation on shaded animals reduces heat stress independently of other means of stress relief. Radiant heat exchange was estimated as a function of climate, shade structure, and animal density. Body surface portion exposed to radiant sources in shaded environments was determined by geometrical relations to determine angles of view of radiation sources (roof underside, sky, sun-exposed ground, shaded ground) on the animal's surface. The relative representation of environment radiation sources on the body surface was determined. Animal thermal radiation balance was derived from radiant heat gained from radiation sources (including surrounding animals) and that lost from the animal surface. The animal environment was assumed to have different shade dimensions and temperatures. These were summed to the radiant heat balance of the cow. The data formed served to estimate the effect of changes in intensity of radiation sources, roof and shaded surface dimensions, and animal density on radiant heat balance (Rbal) of cattle. Roof height effect was expressed by effect of roof temperature on Rbal. Roof underside temperature (35 to 75°C) effect on Rbal was reduced by roof height. If roof height were 4m, an increase in its underside temperature from 35 to 75°C would increase mean Rbal from -63 to -2 W·m⁻², whereas if roof height were 10 m, Rbal would only increase from -99 to -88 W·m⁻². A hot ground temperature increase from 35 to 65°C reduced mean Rbal heat loss from -45 to 3 W·m⁻². Increasing the surface of the shaded area had only a minor effect on Rbal and on the effect of hot ground on Rbal. Increasing shade roof height reduced the effect of roof temperature on Rbal to minor levels when height was > 8m. Increasing the roof height from 4 to 10 m decreased Rbal from -32 to -94 W·m⁻². Increasing indirect radiation from 100 to 500 W·m⁻² was associated with an increase in Rbal from -135 to +23 W·m⁻². Their combined effects were lower

The effect of wind on the rate of heat loss from avian cup-shaped nests.

PubMed

Heenan, Caragh B; Seymour, Roger S

2012-01-01

Forced convection can significantly influence the heat loss from birds and their offspring but effects may be reduced by using sheltered micro-sites such as cavities or constructing nests. The structural and thermal properties of the nests of two species, the spiny-cheeked honeyeater (Acanthagenys rufogularis) and yellow-throated miner (Manorina flavigula), were measured in relation to three wind speeds. Nest dimensions differ between the two species, despite the similar body mass of the incubating adults, however nest conductance is comparable. As wind speed increases, so does the rate of heat loss from the nests of both species, and further still during incubation recesses. The significance of forced convection through the nest is a near-doubling in heat production required by the parent, even when incubating at relatively low wind speeds. This provides confirmation that selecting a sheltered nest site is important for avian reproductive success.

The Effect of Wind on the Rate of Heat Loss from Avian Cup-Shaped Nests

PubMed Central

Heenan, Caragh B.; Seymour, Roger S.

2012-01-01

Forced convection can significantly influence the heat loss from birds and their offspring but effects may be reduced by using sheltered micro-sites such as cavities or constructing nests. The structural and thermal properties of the nests of two species, the spiny-cheeked honeyeater (Acanthagenys rufogularis) and yellow-throated miner (Manorina flavigula), were measured in relation to three wind speeds. Nest dimensions differ between the two species, despite the similar body mass of the incubating adults, however nest conductance is comparable. As wind speed increases, so does the rate of heat loss from the nests of both species, and further still during incubation recesses. The significance of forced convection through the nest is a near-doubling in heat production required by the parent, even when incubating at relatively low wind speeds. This provides confirmation that selecting a sheltered nest site is important for avian reproductive success. PMID:22389689

Numerical analysis of Eucalyptus grandis × E. urophylla heat-treatment: A dynamically detecting method of mass loss during the process

NASA Astrophysics Data System (ADS)

Zhao, Zijian; Ma, Qing; Mu, Jun; Yi, Songlin; He, Zhengbin

Eucalyptus particles, lamellas and boards were applied to explore a simply-implemented method with neglected heat and mass transfer to inspect the mass loss during the heat-treatment course. The results revealed that the mass loss of a certain period was theoretically the definite integration of loss rate to time in this period, and a monitoring model for mass loss speed was developed with the particles and validated with the lamellas and boards. The loss rate was correlated to the temperature and temperature-evolving speed in the model which was composed of three functions during different temperature-evolving period. The sample mass loss was calculated in the MATLAB for the lamellas and boards and the model was validated and adjusted based on the difference between the computed results and the practically measured loss values. The error ranges of the new models were -16.30% to 18.35% for wood lamellas and -9.86% to 6.80% for wood boards. This method made it possible to acquire the instantaneous loss value through continuously detecting the wood temperature evolution. This idea could provide a reference for the Eucalyptus heat-treatment to detect the treating course and control the final material characteristics.

Magnetic flux and heat losses by diffusive, advective, and Nernst effects in magnetized liner inertial fusion-like plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Velikovich, A. L.; Giuliani, J. L.; Zalesak, S. T.

The magnetized liner inertial fusion (MagLIF) approach to inertial confinement fusion [Slutz et al., Phys. Plasmas 17, 056303 (2010); Cuneo et al., IEEE Trans. Plasma Sci. 40, 3222 (2012)] involves subsonic/isobaric compression and heating of a deuterium-tritium plasma with frozen-in magnetic flux by a heavy cylindrical liner. The losses of heat and magnetic flux from the plasma to the liner are thereby determined by plasma advection and gradient-driven transport processes, such as thermal conductivity, magnetic field diffusion, and thermomagnetic effects. Theoretical analysis based on obtaining exact self-similar solutions of the classical collisional Braginskii's plasma transport equations in one dimension demonstratesmore » that the heat loss from the hot compressed magnetized plasma to the cold liner is dominated by transverse heat conduction and advection, and the corresponding loss of magnetic flux is dominated by advection and the Nernst effect. For a large electron Hall parameter (ω{sub e}τ{sub e}≫1), the effective diffusion coefficients determining the losses of heat and magnetic flux to the liner wall are both shown to decrease with ω{sub e}τ{sub e} as does the Bohm diffusion coefficient cT/(16eB), which is commonly associated with low collisionality and two-dimensional transport. We demonstrate how this family of exact solutions can be used for verification of codes that model the MagLIF plasma dynamics.« less

Performance evaluation of cryogenic counter-flow heat exchangers with longitudinal conduction, heat in-leak and property variations

NASA Astrophysics Data System (ADS)

Jiang, Q. F.; Zhuang, M.; Zhu, Z. G.; Y Zhang, Q.; Sheng, L. H.

2017-12-01

Counter-flow plate-fin heat exchangers are commonly utilized in cryogenic applications due to their high effectiveness and compact size. For cryogenic heat exchangers in helium liquefaction/refrigeration systems, conventional design theory is no longer applicable and they are usually sensitive to longitudinal heat conduction, heat in-leak from surroundings and variable fluid properties. Governing equations based on distributed parameter method are developed to evaluate performance deterioration caused by these effects. The numerical model could also be applied in many other recuperators with different structures and, hence, available experimental data are used to validate it. For a specific case of the multi-stream heat exchanger in the EAST helium refrigerator, quantitative effects of these heat losses are further discussed, in comparison with design results obtained by the common commercial software. The numerical model could be useful to evaluate and rate the heat exchanger performance under the actual cryogenic environment.

Determination of heat losses and their influence on the performance characteristics of high-enthalpy hot-shot tubes

NASA Astrophysics Data System (ADS)

Ganimedov, V. L.; Shumsky, V. V.; Yaroslavtsev, M. I.

2009-06-01

An analysis of the losses of heat into the walls of settling chamber in a hypersonic hot-shot tube has been performed. Tests without diaphragm rupture showed that the fall of settling-chamber pressure during the operating flow regime in the tube was the consequence of the transfer of heat from working body to wall; this has allowed us to evaluate the heat-transfer coefficient α and the inner-surface temperature of the wall T w. An empirical formula relating the coefficient α with the pressure and working-body temperature in the settling chamber in the range of pressures and temperatures 160 to 540 bar and 700 to 3400 K was obtained. Using the gained dependences of α and T w on pressure and temperature, we have developed a physical model for calculating the working-body characteristics in the tube with allowance for enthalpy losses. We found that by the hundredth millisecond of the operating regime the disregard, in such calculations, of the wall heat flux in the first settling chamber resulted in overestimation of the stagnation temperature in the test section in comparison with similar calculations made without allowance for the heat losses by 6-18 % in terms of the full-scale temperature for aircraft flight in Mach number range 5 to 8. The developed calculation procedure has been tested in experiments without diaphragm rupture.

Mode and climatic factors effect on energy losses in transient heat modes of transmission lines

NASA Astrophysics Data System (ADS)

Bigun, A. Ya; Sidorov, O. A.; Osipov, D. S.; Girshin, S. S.; Goryunov, V. N.; Petrova, E. V.

2018-01-01

Electrical energy losses increase in modern grids. The losses are connected with an increase in consumption. Existing models of electric power losses estimation considering climatic factors do not allow estimating the cable temperature in real time. Considering weather and mode factors in real time allows to meet effectively and safely the consumer’s needs to minimize energy losses during transmission, to use electric power equipment effectively. These factors increase an interest in the evaluation of the dynamic thermal mode of overhead transmission lines conductors. The article discusses an approximate analytic solution of the heat balance equation in the transient operation mode of overhead lines based on the least squares method. The accuracy of the results obtained is comparable with the results of solving the heat balance equation of transient thermal mode with the Runge-Kutt method. The analysis of mode and climatic factors effect on the cable temperature in a dynamic thermal mode is presented. The calculation of the maximum permissible current for variation of weather conditions is made. The average electric energy losses during the transient process are calculated with the change of wind, air temperature and solar radiation. The parameters having the greatest effect on the transmission capacity are identified.

Episodic Southern Ocean Heat Loss and Its Mixed Layer Impacts Revealed by the Farthest South Multiyear Surface Flux Mooring

NASA Astrophysics Data System (ADS)

Ogle, S. E.; Tamsitt, V.; Josey, S. A.; Gille, S. T.; Cerovečki, I.; Talley, L. D.; Weller, R. A.

2018-05-01

The Ocean Observatories Initiative air-sea flux mooring deployed at 54.08°S, 89.67°W, in the southeast Pacific sector of the Southern Ocean, is the farthest south long-term open ocean flux mooring ever deployed. Mooring observations (February 2015 to August 2017) provide the first in situ quantification of annual net air-sea heat exchange from one of the prime Subantarctic Mode Water formation regions. Episodic turbulent heat loss events (reaching a daily mean net flux of -294 W/m2) generally occur when northeastward winds bring relatively cold, dry air to the mooring location, leading to large air-sea temperature and humidity differences. Wintertime heat loss events promote deep mixed layer formation that lead to Subantarctic Mode Water formation. However, these processes have strong interannual variability; a higher frequency of 2 σ and 3 σ turbulent heat loss events in winter 2015 led to deep mixed layers (>300 m), which were nonexistent in winter 2016.

Preliminary research on eddy current bobbin quantitative test for heat exchange tube in nuclear power plant

NASA Astrophysics Data System (ADS)

Qi, Pan; Shao, Wenbin; Liao, Shusheng

2016-02-01

For quantitative defects detection research on heat transfer tube in nuclear power plants (NPP), two parts of work are carried out based on the crack as the main research objects. (1) Production optimization of calibration tube. Firstly, ASME, RSEM and homemade crack calibration tubes are applied to quantitatively analyze the defects depth on other designed crack test tubes, and then the judgment with quantitative results under crack calibration tube with more accuracy is given. Base on that, weight analysis of influence factors for crack depth quantitative test such as crack orientation, length, volume and so on can be undertaken, which will optimize manufacture technology of calibration tubes. (2) Quantitative optimization of crack depth. Neural network model with multi-calibration curve adopted to optimize natural crack test depth generated in in-service tubes shows preliminary ability to improve quantitative accuracy.

Analysis of heat loss mechanisms for mobile tent-type refuge alternatives.

PubMed

Bissert, P T; Yantek, D S; Klein, M D; Yan, L

2016-01-01

Federal regulations require that refuge alternatives (RAs) be located within 305 m (1,000 ft) of the working face and spaced at one-hour travel distances in the outby area in underground coal mines, in the event that miners cannot escape during a disaster. The Mine Safety and Health Administration mandates that RAs provide safe shelter and livable conditions for a minimum of 96 hours while maintaining the apparent temperature below 35 °C (95 °F). The U.S. National Institute for Occupational Safety and Health used a validated thermal simulation model to examine the mechanisms of heat loss from an RA to the ambient mine and the effect of mine strata composition on the final internal dry bulb temperature (DBT) for a mobile tent-type RA. The results of these studies show that 51 percent of the heat loss from the RA to the ambient mine is due to radiation and 31 percent to conduction. Three mine width and height configurations and four mine strata compositions were examined. The final DBT inside the RA after 96 hours varied by less than 1 °C (1.8 °F) for the three mine width/height configurations and by less than 2 °C (3.6 °F) for the four mine strata compositions.

Quantitative Analysis Method of Output Loss due to Restriction for Grid-connected PV Systems

NASA Astrophysics Data System (ADS)

Ueda, Yuzuru; Oozeki, Takashi; Kurokawa, Kosuke; Itou, Takamitsu; Kitamura, Kiyoyuki; Miyamoto, Yusuke; Yokota, Masaharu; Sugihara, Hiroyuki

Voltage of power distribution line will be increased due to reverse power flow from grid-connected PV systems. In the case of high density grid connection, amount of voltage increasing will be higher than the stand-alone grid connection system. To prevent the over voltage of power distribution line, PV system's output will be restricted if the voltage of power distribution line is close to the upper limit of the control range. Because of this interaction, amount of output loss will be larger in high density case. This research developed a quantitative analysis method for PV systems output and losses to clarify the behavior of grid connected PV systems. All the measured data are classified into the loss factors using 1 minute average of 1 second data instead of typical 1 hour average. Operation point on the I-V curve is estimated to quantify the loss due to the output restriction using module temperature, array output voltage, array output current and solar irradiance. As a result, loss due to output restriction is successfully quantified and behavior of output restriction is clarified.

Chaos of radiative heat-loss-induced flame front instability.

PubMed

Kinugawa, Hikaru; Ueda, Kazuhiro; Gotoda, Hiroshi

2016-03-01

We are intensively studying the chaos via the period-doubling bifurcation cascade in radiative heat-loss-induced flame front instability by analytical methods based on dynamical systems theory and complex networks. Significant changes in flame front dynamics in the chaotic region, which cannot be seen in the bifurcation diagrams, were successfully extracted from recurrence quantification analysis and nonlinear forecasting and from the network entropy. The temporal dynamics of the fuel concentration in the well-developed chaotic region is much more complicated than that of the flame front temperature. It exhibits self-affinity as a result of the scale-free structure in the constructed visibility graph.

Heat transfer in a liquid helium cooled vacuum tube following sudden vacuum loss

NASA Astrophysics Data System (ADS)

Dhuley, R. C.; Van Sciver, S. W.

2015-12-01

Condensation of nitrogen gas rapidly flowing into a liquid helium (LHe) cooled vacuum tube is studied. This study aims to examine the heat transfer in geometries such as the superconducting RF cavity string of a particle accelerator following a sudden loss of vacuum to atmosphere. In a simplified experiment, the flow is generated by quickly venting a large reservoir of nitrogen gas to a straight long vacuum tube immersed in LHe. Normal LHe (LHe I) and superfluid He II are used in separate experiments. The rate of condensation heat transfer is determined from the temperature of the tube measured at several locations along the gas flow. Instantaneous heat deposition rates in excess of 200 kW/m2 result from condensation of the flowing gas. The gas flow is then arrested in its path to pressurize the tube to atmosphere and estimate the heat transfer rate to LHe. A steady LHe I heat load of ≈25 kW/m2 is obtained in this scenario. Observations from the He II experiment are briefly discussed. An upper bound for the LHe I heat load is derived based on the thermodynamics of phase change of nitrogen.

Hyperthermia modifies muscle metaboreceptor and baroreceptor modulation of heat loss in humans.

PubMed

Binder, Konrad; Lynn, Aaron G; Gagnon, Daniel; Kondo, Narihiko; Kenny, Glen P

2012-02-15

The relative influence of muscle metabo- and baroreflex activity on heat loss responses during post-isometric handgrip (IHG) exercise ischemia remains unknown, particularly under heat stress. Therefore, we examined the separate and integrated influences of metabo- and baroreceptor-mediated reflex activity on sweat rate and cutaneous vascular conductance (CVC) under increasing levels of hyperthermia. Twelve men performed 1 min of IHG exercise at 60% of maximal voluntary contraction followed by 2 min of ischemia with simultaneous application of lower body positive pressure (LBPP, +40 mmHg), lower body negative pressure (LBNP, -20 mmHg), or no pressure (control) under no heat stress. On separate days, trials were repeated under heat stress conditions of 0.6°C (moderate heat stress) and 1.4°C (high heat stress) increase in esophageal temperature. For all conditions, mean arterial pressure was greater with LBPP and lower with LBNP than control during ischemia (all P ≤ 0.05). No differences in sweat rate were observed between pressure conditions, regardless of the level of hyperthermia (P > 0.05). Under moderate heat stress, no differences in CVC were observed between pressure conditions. However, under high heat stress, LBNP significantly reduced CVC by 21 ± 4% (P ≤ 0.05) and LBPP significantly elevated CVC by 14 ± 5% (P ≤ 0.05) relative to control. These results show that sweating during post-IHG exercise ischemia is activated by metaboreflex stimulation, and not by baroreflexes. In contrast, our results suggest that baroreflexes can influence the metaboreflex modulation of CVC, but only at greater levels of hyperthermia.

Parasitic heat loss reduction in AMTEC cells by heat shield optimization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Borkowski, C.A.; Svedberg, R.C.; Hendricks, T.J.

1997-12-31

Alkali metal thermal to electric conversion (AMTEC) cell performance can be increased by the proper design of thermal radiative shielding internal to the AMTEC cell. These heat shields essentially lower the radiative heat transfer between the heat input zone of the cell and the heat rejection zone of the cell. In addition to lowering the radiative heat transfer between the heat input and heat rejection surfaces of the cell, the shields raise the AMTEC cell performance by increasing the temperature of the beta alumina solid electrolyte (BASE). This increase in temperature of the BASE tube allows the evaporator temperature tomore » be increased without sodium condensing within the BASE tubes. Experimental testing and theoretical analysis have been performed to compare the relative merits of two candidate heat shield packages: (1) chevron, and (2) cylindrical heat shields. These two heat shield packages were compared to each other and a baseline cell which had no heat shields installed. For the two heat shield packages, the reduction in total heat transfer is between 17--27% for the heat input surface temperature varying from 700 C, 750 C, and 800 C with the heat rejection surface temperature kept at 300 C.« less

Head insulation and heat loss in the newborn.

PubMed Central

Stothers, J K

1981-01-01

The thermal balance of 13 term infants was measured in a closed-circuit metabolism chamber. Each was studied naked, then with a gamgee-lined hat, and finally with a 'cummerbund' made of a similar material and of similar dimensions. At 27 degrees C the oxygen consumption of the 'hatted' babies was only 85% and the total heat loss 75% of the values measured with the infants naked. The cummerbund offered no detectable benefit. An additional 10 infants were studied while wearing a tubegauze hat at environmental temperatures of 28.5 (+/- 0.5) degrees C. This type of hat gave no measurable thermal protection. It is concluded that a substantial reduction of thermal stress in adverse environments can be achieved simply and clearly by adequately covering the vault of the skull. PMID:7271287

A new hue capturing technique for the quantitative interpretation of liquid crystal images used in convective heat transfer studies

NASA Technical Reports Server (NTRS)

Camci, C.; Kim, K.; Hippensteele, S. A.

1992-01-01

A new image processing based color capturing technique for the quantitative interpretation of liquid crystal images used in convective heat transfer studies is presented. This method is highly applicable to the surfaces exposed to convective heating in gas turbine engines. It is shown that, in the single-crystal mode, many of the colors appearing on the heat transfer surface correlate strongly with the local temperature. A very accurate quantitative approach using an experimentally determined linear hue vs temperature relation is found to be possible. The new hue-capturing process is discussed in terms of the strength of the light source illuminating the heat transfer surface, the effect of the orientation of the illuminating source with respect to the surface, crystal layer uniformity, and the repeatability of the process. The present method is more advantageous than the multiple filter method because of its ability to generate many isotherms simultaneously from a single-crystal image at a high resolution in a very time-efficient manner.

Light masking of circadian rhythms of heat production, heat loss, and body temperature in squirrel monkeys

NASA Technical Reports Server (NTRS)

Robinson, E. L.; Fuller, C. A.

1999-01-01

Whole body heat production (HP) and heat loss (HL) were examined to determine their relative contributions to light masking of the circadian rhythm in body temperature (Tb). Squirrel monkey metabolism (n = 6) was monitored by both indirect and direct calorimetry, with telemetered measurement of body temperature and activity. Feeding was also measured. Responses to an entraining light-dark (LD) cycle (LD 12:12) and a masking LD cycle (LD 2:2) were compared. HP and HL contributed to both the daily rhythm and the masking changes in Tb. All variables showed phase-dependent masking responses. Masking transients at L or D transitions were generally greater during subjective day; however, L masking resulted in sustained elevation of Tb, HP, and HL during subjective night. Parallel, apparently compensatory, changes of HL and HP suggest action by both the circadian timing system and light masking on Tb set point. Furthermore, transient HL increases during subjective night suggest that gain change may supplement set point regulation of Tb.

Using Solar Hot Water to Address Piping Heat Losses in Multifamily Buildings

DOE Office of Scientific and Technical Information (OSTI.GOV)

Springer, David; Seitzler, Matt; Backman, Christine

2015-10-01

Solar thermal water heating is most cost effective when applied to multifamily buildings and some states offer incentives or other inducements to install them. However, typical solar water heating designs do not allow the solar generated heat to be applied to recirculation losses, only to reduce the amount of gas or electric energy needed for hot water that is delivered to the fixtures. For good reasons, hot water that is recirculated through the building is returned to the water heater, not to the solar storage tank. The project described in this report investigated the effectiveness of using automatic valves tomore » divert water that is normally returned through the recirculation piping to the gas or electric water heater instead to the solar storage tank. The valves can be controlled so that the flow is only diverted when the returning water is cooler than the water in the solar storage tank.« less

Analysis on the Role of RSG-GAS Pool Cooling System during Partial Loss of Heat Sink Accident

NASA Astrophysics Data System (ADS)

Susyadi; Endiah, P. H.; Sukmanto, D.; Andi, S. E.; Syaiful, B.; Hendro, T.; Geni, R. S.

2018-02-01

RSG-GAS is a 30 MW reactor that is mostly used for radioisotope production and experimental activities. Recently, it is regularly operated at half of its capacity for efficiency reason. During an accident, especially loss of heat sink, the role of its pool cooling system is very important to dump decay heat. An analysis using single failure approach and partial modeling of RELAP5 performed by S. Dibyo, 2010 shows that there is no significant increase in the coolant temperature if this system is properly functioned. However lessons learned from the Fukushima accident revealed that an accident can happen due to multiple failures. Considering ageing of the reactor, in this research the role of pool cooling system is to be investigated for a partial loss of heat sink accident which is at the same time the protection system fails to scram the reactor when being operated at 15 MW. The purpose is to clarify the transient characteristics and the final state of the coolant temperature. The method used is by simulating the system in RELAP5 code. Calculation results shows the pool cooling systems reduce coolant temperature for about 1 K as compared without activating them. The result alsoreveals that when the reactor is being operated at half of its rated power, it is still in safe condition for a partial loss of heat sink accident without scram.

Steps towards understanding deep atmospheric heating in flares

NASA Technical Reports Server (NTRS)

Mauas, Pablo J. D.; Machado, Marcos E.

1986-01-01

Different aspects of the heating of the deep solar atmosphere during flares, including temperature minimum enhancements and white light emission, are discussed. The proper treatment of H(-) radiative losses is discussed, and compared with previous studies, as well as a quantitative analysis of the ionizing effect of nonthermal particles and ultraviolet radiation. It is concluded that temperature minimum heating may be a natural consequence of the global radiation transport in flares. The implications of these results are discussed within the context of homogeneous and inhomogeneous models of the solar atmosphere.

The dry-heat loss effect of melt-spun phase change material fibres.

PubMed

Tjønnås, Maria Suong; Færevik, Hilde; Sandsund, Mariann; Reinertsen, Randi E

2015-01-01

Phase change materials (PCM) have the ability to store latent heat when they change phases, a property that gives clothing that incorporates PCM its cooling effect. This study investigated the effect of dry-heat loss (cooling) of a novel melt-spun PCM fibre on the basis of the area covered, mass, the latent heat of fusion and melting temperature, compared to a known PCM clothing product. PCM fibres with melting temperatures of 28.4 and 32.0°C and PCM packs with melting temperatures of 28.0 and 32.0°C were studied. The results showed that the PCM fibres had a larger initial peak cooling effect than that of the PCM packs. The duration of the cooling effect of PCM fibres was primarily dependent on the PCM mass and the latent heat of fusion capacity, and secondly on the covered area and melting temperature of the PCM. This study investigates the cooling effect of PCM fibres on a thermal manikin. The PCM fibres had a high but short-lasting cooling effect. This study contributes to the knowledge of how the body's temperature regulation may be affected by the cooling properties of clothing that incorporates PCM.

Morphological dependency of cutaneous blood flow and sweating during compensable heat stress when heat-loss requirements are matched across participants.

PubMed

Notley, Sean R; Park, Joonhee; Tagami, Kyoko; Ohnishi, Norikazu; Taylor, Nigel A S

2016-07-01

Human heat loss is thought, in part, to be morphologically related. It was therefore hypothesized that when heat-loss requirements and body temperatures were matched, that the mass-specific surface area alone could significantly explain both cutaneous vascular and sudomotor responses during compensable exercise. These thermoeffector responses were examined in 36 men with widely varying mass-specific surface areas (range, 232.3-292.7 cm(2)/kg), but of similar age, aerobic fitness, and adiposity. Subjects completed two trials under compensable conditions (28.1°C, 36.8% relative humidity), each involving rest (20 min) and steady-state cycling (45 min) at two matched metabolic heat-production rates (light, ∼135 W/m(2); moderate, ∼200 W/m(2)). Following equivalent mean body temperature changes, forearm blood flow and vascular conductance (r = 0.63 and r = 0.65) shared significant, positive associations with the mass-specific surface area during light work (P < 0.05), explaining ∼45% of the vasomotor variation. Conversely, during light and moderate work, whole body sweat rate, as well as local sweat rate and sudomotor sensitivity at three of four measured sites, revealed moderate, negative relationships with the mass-specific surface area (correlation coefficient range -0.37 to -0.73, P < 0.05). Moreover, those relationships could uniquely account for between 10 and 53% of those sweating responses (P < 0.05). Therefore, both thermoeffector responses displayed a significant morphological dependency in the presence of equivalent thermoafferent drive. Indeed, up to half of the interindividual variation in these effector responses could now be explained through morphological differences and the first principles governing heat transfer. Copyright © 2016 the American Physiological Society.

Morphological dependency of cutaneous blood flow and sweating during compensable heat stress when heat-loss requirements are matched across participants

PubMed Central

Notley, Sean R.; Park, Joonhee; Tagami, Kyoko; Ohnishi, Norikazu

2016-01-01

Human heat loss is thought, in part, to be morphologically related. It was therefore hypothesized that when heat-loss requirements and body temperatures were matched, that the mass-specific surface area alone could significantly explain both cutaneous vascular and sudomotor responses during compensable exercise. These thermoeffector responses were examined in 36 men with widely varying mass-specific surface areas (range, 232.3-292.7 cm2/kg), but of similar age, aerobic fitness, and adiposity. Subjects completed two trials under compensable conditions (28.1°C, 36.8% relative humidity), each involving rest (20 min) and steady-state cycling (45 min) at two matched metabolic heat-production rates (light, ∼135 W/m2; moderate, ∼200 W/m2). Following equivalent mean body temperature changes, forearm blood flow and vascular conductance (r = 0.63 and r = 0.65) shared significant, positive associations with the mass-specific surface area during light work (P < 0.05), explaining ∼45% of the vasomotor variation. Conversely, during light and moderate work, whole body sweat rate, as well as local sweat rate and sudomotor sensitivity at three of four measured sites, revealed moderate, negative relationships with the mass-specific surface area (correlation coefficient range −0.37 to −0.73, P < 0.05). Moreover, those relationships could uniquely account for between 10 and 53% of those sweating responses (P < 0.05). Therefore, both thermoeffector responses displayed a significant morphological dependency in the presence of equivalent thermoafferent drive. Indeed, up to half of the interindividual variation in these effector responses could now be explained through morphological differences and the first principles governing heat transfer. PMID:27125845

Heat waves imposed during early pod development in soybean (Glycine max) cause significant yield loss despite a rapid recovery from oxidative stress.

PubMed

Siebers, Matthew H; Yendrek, Craig R; Drag, David; Locke, Anna M; Rios Acosta, Lorena; Leakey, Andrew D B; Ainsworth, Elizabeth A; Bernacchi, Carl J; Ort, Donald R

2015-08-01

Heat waves already have a large impact on crops and are predicted to become more intense and more frequent in the future. In this study, heat waves were imposed on soybean using infrared heating technology in a fully open-air field experiment. Five separate heat waves were applied to field-grown soybean (Glycine max) in central Illinois, three in 2010 and two in 2011. Thirty years of historical weather data from Illinois were analyzed to determine the length and intensity of a regionally realistic heat wave resulting in experimental heat wave treatments during which day and night canopy temperatures were elevated 6 °C above ambient for 3 days. Heat waves were applied during early or late reproductive stages to determine whether and when heat waves had an impact on carbon metabolism and seed yield. By the third day of each heat wave, net photosynthesis (A), specific leaf weight (SLW), and leaf total nonstructural carbohydrate concentration (TNC) were decreased, while leaf oxidative stress was increased. However, A, SLW, TNC, and measures of oxidative stress were no different than the control ca. 12 h after the heat waves ended, indicating rapid physiological recovery from the high-temperature stress. That end of season seed yield was reduced (~10%) only when heat waves were applied during early pod developmental stages indicates the yield loss had more to do with direct impacts of the heat waves on reproductive process than on photosynthesis. Soybean was unable to mitigate yield loss after heat waves given during late reproductive stages. This study shows that short high-temperature stress events that reduce photosynthesis and increase oxidative stress resulted in significant losses to soybean production in the Midwest, U.S. The study also suggests that to mitigate heat wave-induced yield loss, soybean needs improved reproductive and photosynthetic tolerance to high but increasingly common temperatures. Published 2015. This article is a U.S. Government work and is

Is there evidence for nonthermal modulation of whole body heat loss during intermittent exercise?

PubMed

Kenny, Glen P; Gagnon, Daniel

2010-07-01

This study compared the effect of active, passive, and inactive recoveries on whole body evaporative and dry heat loss responses during intermittent exercise at an air temperature of 30 degrees C and a relative humidity of 20%. Nine males performed three 15-min bouts of upright seated cycling at a fixed external workload of 150 W. The exercise bouts were separated by three 15-min recoveries during which participants 1) performed loadless pedaling (active recovery), 2) had their lower limbs passively compressed with inflatable sleeves (passive recovery), or 3) remained upright seated on the cycle ergometer (inactive recovery). Combined direct and indirect calorimetry was employed to measure rates of whole body evaporative heat loss (EHL) and metabolic heat production (M-W). Mean body temperature (T(b)) was calculated from esophageal and mean skin temperatures, and mean arterial pressure (MAP) was measured continuously. Active and passive recoveries both reversed the reduction in MAP associated with inactive recovery (P

Three-Dimensional Photography for Quantitative Assessment of Penile Volume-Loss Deformities in Peyronie's Disease.

PubMed

Margolin, Ezra J; Mlynarczyk, Carrie M; Mulhall, John P; Stember, Doron S; Stahl, Peter J

2017-06-01

Non-curvature penile deformities are prevalent and bothersome manifestations of Peyronie's disease (PD), but the quantitative metrics that are currently used to describe these deformities are inadequate and non-standardized, presenting a barrier to clinical research and patient care. To introduce erect penile volume (EPV) and percentage of erect penile volume loss (percent EPVL) as novel metrics that provide detailed quantitative information about non-curvature penile deformities and to study the feasibility and reliability of three-dimensional (3D) photography for measurement of quantitative penile parameters. We constructed seven penis models simulating deformities found in PD. The 3D photographs of each model were captured in triplicate by four observers using a 3D camera. Computer software was used to generate automated measurements of EPV, percent EPVL, penile length, minimum circumference, maximum circumference, and angle of curvature. The automated measurements were statistically compared with measurements obtained using water-displacement experiments, a tape measure, and a goniometer. Accuracy of 3D photography for average measurements of all parameters compared with manual measurements; inter-test, intra-observer, and inter-observer reliabilities of EPV and percent EPVL measurements as assessed by the intraclass correlation coefficient. The 3D images were captured in a median of 52 seconds (interquartile range = 45-61). On average, 3D photography was accurate to within 0.3% for measurement of penile length. It overestimated maximum and minimum circumferences by averages of 4.2% and 1.6%, respectively; overestimated EPV by an average of 7.1%; and underestimated percent EPVL by an average of 1.9%. All inter-test, inter-observer, and intra-observer intraclass correlation coefficients for EPV and percent EPVL measurements were greater than 0.75, reflective of excellent methodologic reliability. By providing highly descriptive and reliable measurements of

All fiber cladding mode stripper with uniform heat distribution and high cladding light loss manufactured by CO2 laser ablation

NASA Astrophysics Data System (ADS)

Jebali, M. A.; Basso, E. T.

2018-02-01

Cladding mode strippers are primarily used at the end of a fiber laser cavity to remove high-power excess cladding light without inducing core loss and beam quality degradation. Conventional manufacturing methods of cladding mode strippers include acid etching, abrasive blasting or laser ablation. Manufacturing of cladding mode strippers using laser ablation consist of removing parts of the cladding by fused silica ablation with a controlled penetration and shape. We present and characterize an optimized cladding mode stripper design that increases the cladding light loss with a minimal device length and manufacturing time. This design reduces the localized heat generation by improving the heat distribution along the device. We demonstrate a cladding mode stripper written on a 400um fiber with cladding light loss of 20dB, with less than 0.02dB loss in the core and minimal heating of the fiber and coating. The manufacturing process of the designed component is fully automated and takes less than 3 minutes with a very high throughput yield.

Unmanned Aerial Vehicles for Environmental Monitoring with Special Reference to Heat Loss

NASA Astrophysics Data System (ADS)

Anweiler, Stanisław; Piwowarski, Dawid; Ulbrich, Roman

2017-10-01

This paper presents the design and implementation of device for remote and automatic monitoring of temperature field of large objects. The project aimed to create a quadcopter flying platform equipped with a thermal imaging camera. The object of the research was district heating installations above ground and underground. The results of the work on the implementation of low-cost (below 750 EUR) and efficient heat loss monitoring system. The system consists of a small (<2kg) multirotor platform. To perform thermal images micro camera FlirOne with microcomputer Raspberry Pi3 was used. Exploitation of UAVs in temperature field monitoring reveals only a fraction of their capabilities. The fast-growing multirotor platform market continues to deliver new solutions and improvements. Their use in monitoring the environment is limited only by the imagination of the user.

Laser-heated rocket studies

NASA Technical Reports Server (NTRS)

Kemp, N. H.; Root, R. G.; Wu., P. K. S.; Caledonia, G. E.; Pirri, A. N.

1976-01-01

CW laser heated rocket propulsion was investigated in both the flowing core and stationary core configurations. The laser radiation considered was 10.6 micrometers, and the working gas was unseeded hydrogen. The areas investigated included initiation of a hydrogen plasma capable of absorbing laser radiation, the radiation emission properties of hot, ionized hydrogen, the flow of hot hydrogen while absorbing and radiating, the heat losses from the gas and the rocket performance. The stationary core configuration was investigated qualitatively and semi-quantitatively. It was found that the flowing core rockets can have specific impulses between 1,500 and 3,300 sec. They are small devices, whose heating zone is only a millimeter to a few centimeters long, and millimeters to centimeters in radius, for laser power levels varying from 10 to 5,000 kW, and pressure levels of 3 to 10 atm. Heat protection of the walls is a vital necessity, though the fraction of laser power lost to the walls can be as low as 10% for larger powers, making the rockets thermally efficient.

Edge loss of high-harmonic fast-wave heating power in NSTX: a cylindrical model

DOE PAGES

Perkins, R. J.; Hosea, J. C.; Bertelli, N.; ...

2017-09-04

Efficient high-harmonic fast-wave (HHFW) heating in the National Spherical Torus Experiment Upgrade (NSTX-U) would facilitate experiments in turbulence, transport, fast-ion studies, and more. However, previous HHFW operation in NSTX exhibited a large loss of fast-wave power to the divertor along the scrape-off layer field lines for edge densities above the fast-wave cutoff. It was postulated that the wave amplitude is enhanced in the scrapeoff layer due to cavity-like modes, and that these enhanced fields drive sheath losses through RF rectification. As part of ongoing work to confirm this hypothesis, we have developed a cylindrical cold-plasma model to identify and understandmore » scenarios where a substantial fraction of wave power is confined to the plasma periphery. We previously identified a peculiar class of modes, named annulus resonances, that conduct approximately half of their wave power in the periphery and can also account for a significant fraction of the total wave power. Here, we study the influence of annulus resonances on wave field reconstructions and find instances where annulus-resonant modes dominate the spectrum and trap over half of the total wave power at the edge. The work is part of an ongoing effort to determine the mechanism underlying these scrape-off layer losses in NSTX, identify optimal conditions for operation in NSTX-U, and predict whether similar losses occur for the ion-cyclotron minority heating scheme for both current experiments and future devices such as ITER.« less

Edge loss of high-harmonic fast-wave heating power in NSTX: a cylindrical model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Perkins, R. J.; Hosea, J. C.; Bertelli, N.

Efficient high-harmonic fast-wave (HHFW) heating in the National Spherical Torus Experiment Upgrade (NSTX-U) would facilitate experiments in turbulence, transport, fast-ion studies, and more. However, previous HHFW operation in NSTX exhibited a large loss of fast-wave power to the divertor along the scrape-off layer field lines for edge densities above the fast-wave cutoff. It was postulated that the wave amplitude is enhanced in the scrapeoff layer due to cavity-like modes, and that these enhanced fields drive sheath losses through RF rectification. As part of ongoing work to confirm this hypothesis, we have developed a cylindrical cold-plasma model to identify and understandmore » scenarios where a substantial fraction of wave power is confined to the plasma periphery. We previously identified a peculiar class of modes, named annulus resonances, that conduct approximately half of their wave power in the periphery and can also account for a significant fraction of the total wave power. Here, we study the influence of annulus resonances on wave field reconstructions and find instances where annulus-resonant modes dominate the spectrum and trap over half of the total wave power at the edge. The work is part of an ongoing effort to determine the mechanism underlying these scrape-off layer losses in NSTX, identify optimal conditions for operation in NSTX-U, and predict whether similar losses occur for the ion-cyclotron minority heating scheme for both current experiments and future devices such as ITER.« less

Minimizing scatter-losses during pre-heat for magneto-inertial fusion targets

NASA Astrophysics Data System (ADS)

Geissel, Matthias; Harvey-Thompson, Adam J.; Awe, Thomas J.; Bliss, David E.; Glinsky, Michael E.; Gomez, Matthew R.; Harding, Eric; Hansen, Stephanie B.; Jennings, Christopher; Kimmel, Mark W.; Knapp, Patrick; Lewis, Sean M.; Peterson, Kyle; Schollmeier, Marius; Schwarz, Jens; Shores, Jonathon E.; Slutz, Stephen A.; Sinars, Daniel B.; Smith, Ian C.; Speas, C. Shane; Vesey, Roger A.; Weis, Matthew R.; Porter, John L.

2018-02-01

The size, temporal and spatial shape, and energy content of a laser pulse for the pre-heat phase of magneto-inertial fusion affect the ability to penetrate the window of the laser-entrance-hole and to heat the fuel behind it. High laser intensities and dense targets are subject to laser-plasma-instabilities (LPI), which can lead to an effective loss of pre-heat energy or to pronounced heating of areas that should stay unexposed. While this problem has been the subject of many studies over the last decades, the investigated parameters were typically geared towards traditional laser driven Inertial Confinement Fusion (ICF) with densities either at 10% and above or at 1% and below the laser's critical density, electron temperatures of 3-5 keV, and laser powers near (or in excess of) 1 × 1015 W/cm2. In contrast, Magnetized Liner Inertial Fusion (MagLIF) [Slutz et al., Phys. Plasmas 17, 056303 (2010) and Slutz and Vesey, Phys. Rev. Lett. 108, 025003 (2012)] currently operates at 5% of the laser's critical density using much thicker windows (1.5-3.5 μm) than the sub-micron thick windows of traditional ICF hohlraum targets. This article describes the Pecos target area at Sandia National Laboratories using the Z-Beamlet Laser Facility [Rambo et al., Appl. Opt. 44(12), 2421 (2005)] as a platform to study laser induced pre-heat for magneto-inertial fusion targets, and the related progress for Sandia's MagLIF program. Forward and backward scattered light were measured and minimized at larger spatial scales with lower densities, temperatures, and powers compared to LPI studies available in literature.

Protection against cold in prehospital care: evaporative heat loss reduction by wet clothing removal or the addition of a vapor barrier--a thermal manikin study.

PubMed

Henriksson, Otto; Lundgren, Peter; Kuklane, Kalev; Holmér, Ingvar; Naredi, Peter; Bjornstig, Ulf

2012-02-01

In the prehospital care of a cold and wet person, early application of adequate insulation is of utmost importance to reduce cold stress, limit body core cooling, and prevent deterioration of the patient's condition. Most prehospital guidelines on protection against cold recommend the removal of wet clothing prior to insulation, and some also recommend the use of a waterproof vapor barrier to reduce evaporative heat loss. However, there is little scientific evidence of the effectiveness of these measures. Using a thermal manikin with wet clothing, this study was conducted to determine the effect of wet clothing removal or the addition of a vapor barrier on thermal insulation and evaporative heat loss using different amounts of insulation in both warm and cold ambient conditions. A thermal manikin dressed in wet clothing was set up in accordance with the European Standard for assessing requirements of sleeping bags, modified for wet heat loss determination, and the climatic chamber was set to -15 degrees Celsius (°C) for cold conditions and +10°C for warm conditions. Three different insulation ensembles, one, two or seven woollen blankets, were chosen to provide different levels of insulation. Five different test conditions were evaluated for all three levels of insulation ensembles: (1) dry underwear; (2) dry underwear with a vapor barrier; (3) wet underwear; (4) wet underwear with a vapor barrier; and (5) no underwear. Dry and wet heat loss and thermal resistance were determined from continuous monitoring of ambient air temperature, manikin surface temperature, heat flux and evaporative mass loss rate. Independent of insulation thickness or ambient temperature, the removal of wet clothing or the addition of a vapor barrier resulted in a reduction in total heat loss of 19-42%. The absolute heat loss reduction was greater, however, and thus clinically more important in cold environments when little insulation is available. A similar reduction in total heat loss

An augmented classical least squares method for quantitative Raman spectral analysis against component information loss.

PubMed

Zhou, Yan; Cao, Hui

2013-01-01

We propose an augmented classical least squares (ACLS) calibration method for quantitative Raman spectral analysis against component information loss. The Raman spectral signals with low analyte concentration correlations were selected and used as the substitutes for unknown quantitative component information during the CLS calibration procedure. The number of selected signals was determined by using the leave-one-out root-mean-square error of cross-validation (RMSECV) curve. An ACLS model was built based on the augmented concentration matrix and the reference spectral signal matrix. The proposed method was compared with partial least squares (PLS) and principal component regression (PCR) using one example: a data set recorded from an experiment of analyte concentration determination using Raman spectroscopy. A 2-fold cross-validation with Venetian blinds strategy was exploited to evaluate the predictive power of the proposed method. The one-way variance analysis (ANOVA) was used to access the predictive power difference between the proposed method and existing methods. Results indicated that the proposed method is effective at increasing the robust predictive power of traditional CLS model against component information loss and its predictive power is comparable to that of PLS or PCR.

Effects of thickness, insulation, and surface color on the net heat loss through an adobe wall

DOE Office of Scientific and Technical Information (OSTI.GOV)

Herman, R.W.

1980-01-01

A finite difference computer program was written and run to study the net thermal losses through a large variety of adobe walls. Fifty-four different combinations of surface color, wall thickness, and insulation position and R value were modeled over a typical two week winter period for locations similar to Albuquerque, New Mexico. A transient analysis of the heat loss from the room to the interior wall surface was compared to both conventional U value and steady-state calculations.

Quantitative fluorescence loss in photobleaching for analysis of protein transport and aggregation

PubMed Central

2012-01-01

Background Fluorescence loss in photobleaching (FLIP) is a widely used imaging technique, which provides information about protein dynamics in various cellular regions. In FLIP, a small cellular region is repeatedly illuminated by an intense laser pulse, while images are taken with reduced laser power with a time lag between the bleaches. Despite its popularity, tools are lacking for quantitative analysis of FLIP experiments. Typically, the user defines regions of interest (ROIs) for further analysis which is subjective and does not allow for comparing different cells and experimental settings. Results We present two complementary methods to detect and quantify protein transport and aggregation in living cells from FLIP image series. In the first approach, a stretched exponential (StrExp) function is fitted to fluorescence loss (FL) inside and outside the bleached region. We show by reaction–diffusion simulations, that the StrExp function can describe both, binding/barrier–limited and diffusion-limited FL kinetics. By pixel-wise regression of that function to FL kinetics of enhanced green fluorescent protein (eGFP), we determined in a user-unbiased manner from which cellular regions eGFP can be replenished in the bleached area. Spatial variation in the parameters calculated from the StrExp function allow for detecting diffusion barriers for eGFP in the nucleus and cytoplasm of living cells. Polyglutamine (polyQ) disease proteins like mutant huntingtin (mtHtt) can form large aggregates called inclusion bodies (IB’s). The second method combines single particle tracking with multi-compartment modelling of FL kinetics in moving IB’s to determine exchange rates of eGFP-tagged mtHtt protein (eGFP-mtHtt) between aggregates and the cytoplasm. This method is self-calibrating since it relates the FL inside and outside the bleached regions. It makes it therefore possible to compare release kinetics of eGFP-mtHtt between different cells and experiments. Conclusions We

Life cycle biological efficiency of mice divergently selected for heat loss.

PubMed

Bhatnagar, A S; Nielsen, M K

2014-08-01

Divergent selection in mice for heat loss was conducted in 3 independent replicates creating a high maintenance, high heat loss (MH) and low maintenance, low heat loss (ML) line and unselected control (MC). Improvement in feed efficiency was observed in ML mice due to a reduced maintenance energy requirement but there was also a slight decline in reproductive performance, survivability, and lean content, particularly when compared to MC animals. The objective of this study was to model a life cycle scenario similar to a livestock production system and calculate total inputs and outputs to estimate overall biological efficiency of these lines and determine if reduced feed intake resulted in improved life cycle efficiency. Feed intake, reproductive performance, growth, and body composition were recorded on 21 mating pairs from each line × replicate combination, cohabitated at 7 wk of age and maintained for up to 1 yr unless culled. Proportion of animals at each parity was calculated from survival rates estimated from previous research when enforcing a maximum of 4, 8, or 12 allowed parities. This parity distribution was then combined with values from previous studies to calculate inputs and outputs of mating pairs and offspring produced in a single cycle at equilibrium. Offspring output was defined as kilograms of lean output of offspring at 49 d. Offspring input was defined as megacalories of energy intake for growing offspring from 21 to 49 d. Parent output was defined as kilograms of lean output of culled parents. Parent input was defined as megacalories of energy intake for mating pairs from weaning of one parity to weaning of the next. Offspring output was greatest in MC mice due to superior BW and numbers weaned, while output was lowest in ML mice due to smaller litter sizes and lean content. Parent output did not differ substantially between lines but was greatest in MH mice due to poorer survival rates resulting in more culled animals. Input was greatest in

Do metaboreceptors alter heat loss responses following dynamic exercise?

PubMed

McGinn, Ryan; Swift, Brendan; Binder, Konrad; Gagnon, Daniel; Kenny, Glen P

2014-01-01

Metaboreceptor activation during passive heating is known to influence cutaneous vascular conductance (CVC) and sweat rate (SR). However, whether metaboreceptors modulate the suppression of heat loss following dynamic exercise remains unclear. On separate days, before and after 15 min of high-intensity treadmill running in the heat (35°C), eight males underwent either 1) no isometric handgrip exercise (IHG) or ischemia (CON), 2) 1 min IHG (60% of maximum, IHG), 3) 1 min IHG followed by 2 min of ischemia (IHG+OCC), 4) 2 min of ischemia (OCC), or 5) 1 min IHG followed by 2 min of ischemia with application of lower body negative pressure (IHG+LBNP). SR (ventilated capsule), cutaneous blood flow (Laser-Doppler), and mean arterial pressure (Finometer) were measured continuously before and after dynamic exercise. Following dynamic exercise, CVC was reduced with IHG exercise (P < 0.05) and remained attenuated with post-IHG ischemia during IHG+OCC relative to CON (39 ± 2 vs. 47 ± 6%, P < 0.05). Furthermore, the reduction in CVC was exacerbated by application of LBNP during post-IHG ischemia (35 ± 3%, P < 0.05) relative to IHG+OCC. SR increased during IHG exercise (P < 0.05) and remained elevated during post-IHG ischemia relative to CON following dynamic exercise (0.94 ± 0.15 vs. 0.53 ± 0.09 mg·min(-1)·cm(-2), P < 0.05). In contrast, application of LBNP during post-IHG ischemia had no effect on SR (0.93 ± 0.09 mg·min(-1)·cm(-2), P > 0.05) relative to post-IHG ischemia during IHG+OCC. We show that CVC is reduced and that SR is increased by metaboreceptor activation following dynamic exercise. In addition, we show that the metaboreflex-induced loading of the baroreceptors can influence the CVC response, but not the sweating response.

Effects of vertically ribbed surface roughness on the forced convective heat losses in central receiver systems

NASA Astrophysics Data System (ADS)

Uhlig, Ralf; Frantz, Cathy; Fritsch, Andreas

2016-05-01

External receiver configurations are directly exposed to ambient wind. Therefore, a precise determination of the convective losses is a key factor in the prediction and evaluation of the efficiency of the solar absorbers. Based on several studies, the forced convective losses of external receivers are modeled using correlations for a roughened cylinder in a cross-flow of air. However at high wind velocities, the thermal efficiency measured during the Solar Two experiment was considerably lower than the efficiency predicted by these correlations. A detailed review of the available literature on the convective losses of external receivers has been made. Three CFD models of different level of detail have been developed to analyze the influence of the actual shape of the receiver and tower configuration, of the receiver shape and of the absorber panels on the forced convective heat transfer coefficients. The heat transfer coefficients deduced from the correlations have been compared to the results of the CFD simulations. In a final step the influence of both modeling approaches on the thermal efficiency of an external tubular receiver has been studied in a thermal FE model of the Solar Two receiver.

Impact of Subgrid Scale Models and Heat Loss on Large Eddy Simulations of a Premixed Jet Burner Using Flamelet-Generated Manifolds

NASA Astrophysics Data System (ADS)

Hernandez Perez, Francisco E.; Im, Hong G.; Lee, Bok Jik; Fancello, Alessio; Donini, Andrea; van Oijen, Jeroen A.; de Goey, L. Philip H.

2017-11-01

Large eddy simulations (LES) of a turbulent premixed jet flame in a confined chamber are performed employing the flamelet-generated manifold (FGM) method for tabulation of chemical kinetics and thermochemical properties, as well as the OpenFOAM framework for computational fluid dynamics. The burner has been experimentally studied by Lammel et al. (2011) and features an off-center nozzle, feeding a preheated lean methane-air mixture with an equivalence ratio of 0.71 and mean velocity of 90 m/s, at 573 K and atmospheric pressure. Conductive heat loss is accounted for in the FGM tabulation via burner-stabilized flamelets and the subgrid-scale (SGS) turbulence-chemistry interaction is modeled via presumed filtered density functions. The impact of heat loss inclusion as well as SGS modeling for both the SGS stresses and SGS variance of progress variable on the numerical results is investigated. Comparisons of the LES results against measurements show a significant improvement in the prediction of temperature when heat losses are incorporated into FGM. While further enhancements in the LES results are accomplished by using SGS models based on transported quantities and/or dynamically computed coefficients as compared to the Smagorinsky model, heat loss inclusion is more relevant. This research was sponsored by King Abdullah University of Science and Technology (KAUST) and made use of computational resources at KAUST Supercomputing Laboratory.

Heat loss and drag of spherical drop tube samples

NASA Technical Reports Server (NTRS)

Wallace, D. B.

1982-01-01

Analysis techniques for three aspects of the performance of the NASA/MSFC 32 meter drop tube are considered. Heat loss through the support wire in a pendant drop sample, temperature history of a drop falling through the drop tube when the tube is filled with helium gas at various pressures, and drag and resulting g-levels experienced by a drop falling through the tube when the tube is filled with helium gas at various pressures are addressed. The developed methods apply to systems with sufficiently small Knudsen numbers for which continuum theory may be applied. Sample results are presented, using niobium drops, to indicate the magnitudes of the effects. Helium gas at one atmosphere pressure can approximately double the amount of possible undercooling but it results in an apparent gravity levels of up to 0.1 g.

[Quantitative analysis of blood loss in liposuction].

PubMed

Schor, N; Zatz, R M; Mendonça, A R; Takatu, P M; Patto, G S

1989-01-01

This study was performed in 15 female patients submitted to suction lipectomy as an isolated procedure, to establish blood loss in the procedure. A wide variation of blood-to-fat ratios was observed (17 to 59%) with a mean blood loss in lipoaspirates of 34 +/- 3%. Internal blood losses occurring in the first 72 post-operative hours were as important as or more important than external losses, and responsible for a mean 7% fall in the level of hemoglobin. Internal blood losses occurred between 72 hours and the 7th to the 10th post-operative days and were responsible for a mean 3% fall in the level of hemoglobin. Blood losses occurring in this study were demonstrated to be greater than usually assumed. Some prophylactic measures are recommended to provide for a safer treatment of these patients: an iron supplementation during the pre-operative period; careful clinical and laboratorial screening for bleeding disorders and for the intake of drugs that can interfere with coagulation; use of smaller-diameter cannulas for aspiration, auto-transfusion when aspirating in excess of 1,000 ml, and limiting the aspiration to 1,500 ml.

Double wall versus single wall incubator for reducing heat loss in very low birth weight infants in incubators.

PubMed

Laroia, N; Phelps, D L; Roy, J

2007-04-18

Studies have shown improved survival of newborn infants maintained in the thermoneutral range. The concept of an incubator with additional insulation, a double plexiglass wall, is appealing for very low birth weight infants as it may help to provide a thermoneutral environment. To assess the effects of double walled incubator versus a single wall incubator on insensible water loss, rate of oxygen consumption, episodes of hypothermia, time to regain birth weight, duration of hospitalization and infant mortality in premature infants. The standard search strategy of the Cochrane Neonatal Review Group was used. This included searches of electronic databases: Oxford Database of Perinatal Trials, Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, Issue 1, 2006), MEDLINE (1966 - 2006), EMBASE, previous reviews including cross references, abstracts, conference and symposia proceedings, expert informants in all published languages, and CINAHL (1982 - 2006). Only studies using random or quasi-random methods of allocation were considered for this review. Eligible studies assessed at least one of the outcome variables identified as important to this topic. Independent data extraction and quality assessment of included trials was conducted by the review authors. Data were analyzed using generic inverse variance methodology and weighted mean difference (WMD). Results are presented with 95% confidence intervals. Meta-analysis was undertaken using a fixed effect model. Three studies met the criteria. Four other studies were excluded, as they did not compare double versus single wall incubators (details of the studies are given in the included and excluded studies section). Double wall incubators have the advantage of decreasing heat loss, decreasing heat production and decreasing radiant heat loss when compared to single wall incubators. There is also the advantage of reduced oxygen consumption. A minimal increase in conductive heat loss was noted when

A quantitative determination of air-water heat fluxes in Hermit Lake, New Hampshire under varying meteorological conditions, time of day, and time of year

NASA Astrophysics Data System (ADS)

Kyper, Nicholas D.

An extensive heat flux study is performed at Hermit Lake, New Hampshire from May 26, 2010 till November 7, 2010 to determine the effects of the five individual heat fluxes on Hermit Lake and the surrounding amphibian community. Hermit Lake was chosen due to the relatively long meteorological observations record within the White Mountains of New Hampshire, a new lakeside meteorological station, and ongoing phenology studies of the surrounding eco-system. Utilizing meteorological data from the lakeside weather station and moored water temperature sensors, the incident (Qi), blackbody ( Qbnet ), latent (Qe), sensible (Q s), and net (Qn) heat fluxes are calculated. The incident heat flux is the dominate term in the net flux, accounting for 93% of the variance found in Qn and producing a heat gain of ˜ 19x108 J m-2 throughout the period of study. This large gain produces a net gain of heat in the lake until October 1, 2010, where gains by Qi are offset by the large combined losses of Qbnet , Qs, and Qe thereby producing a gradual decline of heat within the lake. The latent and blackbody heat fluxes produce the largest losses of heat in the net heat flux with a total losses of ˜ -8x108 J m-2 and ˜ -7x108 J m-2, respectively. The sensible heat flux is negligible, producing a total minimal loss of ˜ -1x108 J m-2. Overall the net heat produces a net gain of heat of 2x108 J m-2 throughout the study period. Frog calls indicative of breeding are recorded from May 26, 2010 until August 16, 2010. The spring peeper, American toad, and green frog each produced enough actively calling days to be compared to air temperature, surface water temperature, and wind speed data, as well as data from the five heat fluxes. Linear regression analysis reveals that certain water temperature thresholds affect the calling activities of the spring peeper and green frog, while higher wind speeds have a dramatic effect on the calling activities of both the green frog and American toad. All three

Bulk refrigeration of fruits and vegetables. Part 2: Computer algorithm for heat loads and moisture loss

DOE Office of Scientific and Technical Information (OSTI.GOV)

Becker, B.; Misra, A.; Fricke, B.A.

1997-12-31

A computer algorithm was developed that estimates the latent and sensible heat loads due to the bulk refrigeration of fruits and vegetables. The algorithm also predicts the commodity moisture loss and temperature distribution which occurs during refrigeration. Part 1 focused upon the thermophysical properties of commodities and the flowfield parameters which govern the heat and mass transfer from fresh fruits and vegetables. This paper, Part 2, discusses the modeling methodology utilized in the current computer algorithm and describes the development of the heat and mass transfer models. Part 2 also compares the results of the computer algorithm to experimental datamore » taken from the literature and describes a parametric study which was performed with the algorithm. In addition, this paper also reviews existing numerical models for determining the heat and mass transfer in bulk loads of fruits and vegetables.« less

Ongoing hydrothermal heat loss from the 1912 ash-flow sheet, Valley of Ten Thousand Smokes, Alaska

USGS Publications Warehouse

Hogeweg, N.; Keith, T.E.C.; Colvard, E.M.; Ingebritsen, S.E.

2005-01-01

The June 1912 eruption of Novarupta filled nearby glacial valleys on the Alaska Peninsula with ash-flow tuff (ignimbrite), and post-eruption observations of thousands of steaming fumaroles led to the name 'Valley of Ten Thousand Smokes' (VTTS). By the late 1980s most fumarolic activity had ceased, but the discovery of thermal springs in mid-valley in 1987 suggested continued cooling of the ash-flow sheet. Data collected at the mid-valley springs between 1987 and 2001 show a statistically significant correlation between maximum observed chloride (Cl) concentration and temperature. These data also show a statistically significant decline in the maximum Cl concentration. The observed variation in stream chemistry across the sheet strongly implies that most solutes, including Cl, originate within the area of the VTTS occupied by the 1912 deposits. Numerous measurements of Cl flux in the Ukak River just below the ash-flow sheet suggest an ongoing heat loss of ???250 MW. This represents one of the largest hydrothermal heat discharges in North America. Other hydrothermal discharges of comparable magnitude are related to heat obtained from silicic magma bodies at depth, and are quasi-steady on a multidecadal time scale. However, the VTTS hydrothermal flux is not obviously related to a magma body and is clearly declining. Available data provide reasonable boundary and initial conditions for simple transient modeling. Both an analytical, conduction-only model and a numerical model predict large rates of heat loss from the sheet 90 years after deposition.

Global earthquake casualties due to secondary effects: A quantitative analysis for improving PAGER losses

USGS Publications Warehouse

Wald, David J.

2010-01-01

This study presents a quantitative and geospatial description of global losses due to earthquake-induced secondary effects, including landslide, liquefaction, tsunami, and fire for events during the past 40 years. These processes are of great importance to the US Geological Survey’s (USGS) Prompt Assessment of Global Earthquakes for Response (PAGER) system, which is currently being developed to deliver rapid earthquake impact and loss assessments following large/significant global earthquakes. An important question is how dominant are losses due to secondary effects (and under what conditions, and in which regions)? Thus, which of these effects should receive higher priority research efforts in order to enhance PAGER’s overall assessment of earthquakes losses and alerting for the likelihood of secondary impacts? We find that while 21.5% of fatal earthquakes have deaths due to secondary (non-shaking) causes, only rarely are secondary effects the main cause of fatalities. The recent 2004 Great Sumatra–Andaman Islands earthquake is a notable exception, with extraordinary losses due to tsunami. The potential for secondary hazards varies greatly, and systematically, due to regional geologic and geomorphic conditions. Based on our findings, we have built country-specific disclaimers for PAGER that address potential for each hazard (Earle et al., Proceedings of the 14th World Conference of the Earthquake Engineering, Beijing, China, 2008). We will now focus on ways to model casualties from secondary effects based on their relative importance as well as their general predictability.

Heat transfer and loss by whole-body hyperthermia during severe lower-body heating are impaired in healthy older men.

PubMed

Brazaitis, Marius; Paulauskas, Henrikas; Eimantas, Nerijus; Obelieniene, Diana; Baranauskiene, Neringa; Skurvydas, Albertas

2017-10-01

Most studies demonstrate that aging is associated with a weakened thermoregulation. However, it remains unclear whether heat transfer (for heat loss) from the lower (uncompensable) to the upper (compensable) body during passively-induced severe lower-body heating is delayed or attenuated with aging. Therefore, the main purpose of this study was to investigate heat transfer from uncompensable to compensable body areas in young men and healthy older men during passively-induced whole-body hyperthermia with a demonstrated post-heating change in core body (rectal; T re ) temperature. Nine healthy older men and eleven healthy young men (69±6 vs. 21±1 years old, mean±SD, P<0.05) participated in passively-induced severe lower-body heating in water at approximately 43°C. Despite a similar increment in T re (approximately 2.5°C) in both groups, the heating rate was significantly lower in older men than in young men (1.69±0.12 vs. 2.47±0.29°C/h, respectively; P<0.05). The temperature increase in calf muscle and calf skin (uncompensable areas) was significantly higher in older men than in young men (5.10±0.18 vs. 3.99±0.14°C; P<0.05 and 9.92±0.22 vs. 7.65±0.33°C; P<0.05, respectively). However, the temperature increase in back skin and forearm skin (compensable areas) was significantly lower in older men than in young men (0.76±0.63 vs. 2.83±0.68°C; P<0.05 and 0.39±0.76 vs. 2.73±0.5°C; P<0.05, respectively). Furthermore, a post-warming increase in T re of approximately 0.2°C was observed only in older men (P<0.05). In conclusion, older men whose lower extremities were immersed showed greater accumulation and storage of heat in the skin and deep muscles than young men, and this was associated with a greater heat-transfer delay and subsequent inertia in the increased core body (T re ) temperature. Copyright © 2017 Elsevier Inc. All rights reserved.

Identification of quantitative trait loci for body temperature, body weight, breast yield, and digestibility in an advanced intercross line of chickens under heat stress.

PubMed

Van Goor, Angelica; Bolek, Kevin J; Ashwell, Chris M; Persia, Mike E; Rothschild, Max F; Schmidt, Carl J; Lamont, Susan J

2015-12-17

Losses in poultry production due to heat stress have considerable negative economic consequences. Previous studies in poultry have elucidated a genetic influence on response to heat. Using a unique chicken genetic resource, we identified genomic regions associated with body temperature (BT), body weight (BW), breast yield, and digestibility measured during heat stress. Identifying genes associated with a favorable response during high ambient temperature can facilitate genetic selection of heat-resilient chickens. Generations F18 and F19 of a broiler (heat-susceptible) × Fayoumi (heat-resistant) advanced intercross line (AIL) were used to fine-map quantitative trait loci (QTL). Six hundred and thirty-one birds were exposed to daily heat cycles from 22 to 28 days of age, and phenotypes were measured before heat treatment, on the 1st day and after 1 week of heat treatment. BT was measured at these three phases and BW at pre-heat treatment and after 1 week of heat treatment. Breast muscle yield was calculated as the percentage of BW at day 28. Ileal feed digestibility was assayed from digesta collected from the ileum at day 28. Four hundred and sixty-eight AIL were genotyped using the 600 K Affymetrix chicken SNP (single nucleotide polymorphism) array. Trait heritabilities were estimated using an animal model. A genome-wide association study (GWAS) for these traits and changes in BT and BW was conducted using Bayesian analyses. Candidate genes were identified within 200-kb regions around SNPs with significant association signals. Heritabilities were low to moderate (0.03 to 0.35). We identified QTL for BT on Gallus gallus chromosome (GGA)14, 15, 26, and 27; BW on GGA1 to 8, 10, 14, and 21; dry matter digestibility on GGA19, 20 and 21; and QTL of very large effect for breast muscle yield on GGA1, 15, and 22 with a single 1-Mb window on GGA1 explaining more than 15% of the genetic variation. This is the first study to estimate heritabilities and perform GWAS using this

Comparison of the Heat Release Rate from the Mass Loss Calorimeter to the Cone Calorimeter for Wood-based Materials

Treesearch

Laura E. Hasburgh; Robert H. White; Mark A. Dietenberger; Charles R. Boardman

2015-01-01

There is a growing demand for material properties to be used as inputs in fi re behavior models designed to address building fire safety. This comparative study evaluates using the mass loss calorimeter as an alternative to the cone calorimeter for obtaining heat release rates of wood-based materials. For this study, a modified mass loss calorimeter utilized an...

Optimizing alignment and growth of low-loss YAG single crystal fibers using laser heated pedestal growth technique.

PubMed

Bera, Subhabrata; Nie, Craig D; Soskind, Michael G; Harrington, James A

2017-12-10

The effect of misalignments of different optical components in the laser heated pedestal growth apparatus have been modeled using Zemax optical design software. By isolating the misalignments causing the non-uniformity in the melt zone, the alignment of the components was fine-tuned. Using this optimized alignment, low-loss YAG single crystal fibers of 120 μm diameter were grown, with total attenuation loss as low as 0.5 dB/m at 1064 nm.

Maximum Expected Wall Heat Flux and Maximum Pressure After Sudden Loss of Vacuum Insulation on the Stratospheric Observatory for Infrared Astronomy (SOFIA) Liquid Helium (LHe) Dewars

NASA Technical Reports Server (NTRS)

Ungar, Eugene K.

2014-01-01

The aircraft-based Stratospheric Observatory for Infrared Astronomy (SOFIA) is a platform for multiple infrared observation experiments. The experiments carry sensors cooled to liquid helium (LHe) temperatures. A question arose regarding the heat input and peak pressure that would result from a sudden loss of the dewar vacuum insulation. Owing to concerns about the adequacy of dewar pressure relief in the event of a sudden loss of the dewar vacuum insulation, the SOFIA Program engaged the NASA Engineering and Safety Center (NESC). This report summarizes and assesses the experiments that have been performed to measure the heat flux into LHe dewars following a sudden vacuum insulation failure, describes the physical limits of heat input to the dewar, and provides an NESC recommendation for the wall heat flux that should be used to assess the sudden loss of vacuum insulation case. This report also assesses the methodology used by the SOFIA Program to predict the maximum pressure that would occur following a loss of vacuum event.

Fission product transport analysis in a loss of decay heat removal accident at Browns Ferry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wichner, R.P.; Weber, C.F.; Hodge, S.A.

1984-01-01

This paper summarizes an analysis of the movement of noble gases, iodine, and cesium fission products within the Mark-I containment BWR reactor system represented by Browns Ferry Unit 1 during a postulated accident sequence initiated by a loss of decay heat removal (DHR) capability following a scram. The event analysis showed that this accident could be brought under control by various means, but the sequence with no operator action ultimately leads to containment (drywell) failure followed by loss of water from the reactor vessel, core degradation due to overheating, and reactor vessel failure with attendant movement of core debris ontomore » the drywell floor.« less

Influence of the pineal gland and melatonin on blood flow and evaporative water loss during heat stress in rats.

PubMed

Harlow, H J

1987-01-01

Plasma melatonin levels of laboratory rats were elevated both during acute heat exposure (43 degrees C for 40 min) and chronic exposure (33 degrees C for 17 days) suggesting a possible correlation between melatonin and thermoregulatory mechanisms. Pinealectomy reduced the nighttime elevation in oxygen consumption and evaporative water loss. In addition, pinealectomized animals exhibited a significantly lower cutaneous evaporative water loss both at night and during the day when exposed to an acute heat exposure of 38 degrees C for 45 min. Pinealectomy elevated the blood pressure over the control group whereas melatonin infusion depressed the blood pressure without altering the cardiac output. This relationship implies an action by melatonin on the peripheral vasculature. In support of this conclusion, melatonin pretreatment tended to dampen the vasopressive effect of infused norepinephrine. These data, therefore, suggest a role of the pineal gland and melatonin in thermoregulation through an influence on the cardiovascular system and evaporative water loss.

Quantitative trait loci mapping of heat tolerance in broccoli (Brassica oleracea var. italica) using genotyping-by-sequencing

USDA-ARS?s Scientific Manuscript database

Predicted rising global temperatures due to climate change have generated a demand for crops that are resistant to yield and quality losses from heat stress. Broccoli (Brassica oleracea var. italica) is a cool weather crop with high temperatures during production decreasing both head quality and yie...

Ceramic tube seals cut heat loss, achieve six month payback

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1985-11-01

The methane reformer at the Celanese Chemical Company's Bishop, TX plant operates at approximately 1900/sup 0/F. The reformer has 32 tubes (9'' diameter) that pass through the firebox. Openings around the tubes measure 11'' in diameter to accommodate horizontal and vertical thermal expansion and movement as well as to facilitate tube removal. The gaps around the tubes permitted cool air to be drawn into the firebox (caused by slight negative pressure) and also allowed radiant heat to escape causing the reformer to operate at a lower than desired level of thermal efficiency. Celanese contracted to retrofit the old rigid firebrickmore » roof in the methane reformer with a 10'' thick ceramic fiber module lining. The gaps around the tubes were sealed by using a special tube seal made from Nextel woven ceramic fiber fabric, a 1984 CHEMICAL PROCESSING Vaaler Award winner (Mid-November 1984, p.52). The Nextel fabric used in this application is a heat resistant textile that has a continuous use temperature of 2200/sup 0/F - well above the 1900/sup 0/F operating temperature of the reformer. The tube seals have been working exactly as intended, verified by observation through inspection ports. Temperatures in the penthouse area above the roof dropped from 240/sup 0/F to 150/sup 0/F. The reduction in heat losses has been attributed to the elimination of the gaps around each tube by the seals and to the improved K-factor of the ceramic module lining. The tube seals have paid for themselves within six months of installation. At that time, the seal boots were inspected and showed no signs of wear. With these results, the improved efficiency of the methane reformer promises to yield additional economic benefits.« less

Additional double-wall roof in single-wall, closed, convective incubators: Impact on body heat loss from premature infants and optimal adjustment of the incubator air temperature.

PubMed

Delanaud, Stéphane; Decima, Pauline; Pelletier, Amandine; Libert, Jean-Pierre; Stephan-Blanchard, Erwan; Bach, Véronique; Tourneux, Pierre

2016-09-01

Radiant heat loss is high in low-birth-weight (LBW) neonates. Double-wall or single-wall incubators with an additional double-wall roof panel that can be removed during phototherapy are used to reduce Radiant heat loss. There are no data on how the incubators should be used when this second roof panel is removed. The aim of the study was to assess the heat exchanges in LBW neonates in a single-wall incubator with and without an additional roof panel. To determine the optimal thermoneutral incubator air temperature. Influence of the additional double-wall roof was assessed by using a thermal mannequin simulating a LBW neonate. Then, we calculated the optimal incubator air temperature from a cohort of human LBW neonate in the absence of the additional roof panel. Twenty-three LBW neonates (birth weight: 750-1800g; gestational age: 28-32 weeks) were included. With the additional roof panel, R was lower but convective and evaporative skin heat losses were greater. This difference can be overcome by increasing the incubator air temperature by 0.15-0.20°C. The benefit of an additional roof panel was cancelled out by greater body heat losses through other routes. Understanding the heat transfers between the neonate and the environment is essential for optimizing incubators. Copyright © 2016 IPEM. Published by Elsevier Ltd. All rights reserved.

Quantitative trait locus on chromosome X affects bone loss after maturation in mice.

PubMed

Okudaira, Shuzo; Shimizu, Motoyuki; Otsuki, Bungo; Nakanishi, Rika; Ohta, Akira; Higuchi, Keiichi; Hosokawa, Masanori; Tsuboyama, Tadao; Nakamura, Takashi

2010-09-01

Genetic programming is known to affect the peak bone mass and bone loss after maturation. However, little is known about how polymorphic genes on chromosome X (Chr X) modulate bone loss after maturation. We previously reported a quantitative trait locus (QTL) on Chr X, designated Pbd3, which had a suggestive linkage to bone mass, in male SAMP2 and SAMP6 mice. In this study, we aimed to clarify the effects of Pbd3 on the skeletal phenotype. We generated a congenic strain, P2.P6-X, carrying a 45.6-cM SAMP6-derived Chr X interval on a SAMP2 genetic background. The effects of Pbd3 on the bone phenotype were determined by microcomputed tomography (microCT), whole-body dual-energy X-ray absorptiometry (DXA), serum bone turnover markers, and histomorphometric parameters. Both the bone area fraction (BA/TA) on microCT and whole-body DXA revealed reduced bone loss in P2.P6-X compared with that in SAMP2. The serum concentrations of bone turnover markers at 4 months of age were significantly lower in P2.P6-X than in SAMP2, but did not differ at 8 months of age. These results were observed in female mice, but not in male mice. In conclusion, a QTL within a segregated 45.6-cM interval on Chr X is sex-specifically related to the rate of bone loss after maturation.

Global earthquake casualties due to secondary effects: A quantitative analysis for improving rapid loss analyses

USGS Publications Warehouse

Marano, K.D.; Wald, D.J.; Allen, T.I.

2010-01-01

This study presents a quantitative and geospatial description of global losses due to earthquake-induced secondary effects, including landslide, liquefaction, tsunami, and fire for events during the past 40 years. These processes are of great importance to the US Geological Survey's (USGS) Prompt Assessment of Global Earthquakes for Response (PAGER) system, which is currently being developed to deliver rapid earthquake impact and loss assessments following large/significant global earthquakes. An important question is how dominant are losses due to secondary effects (and under what conditions, and in which regions)? Thus, which of these effects should receive higher priority research efforts in order to enhance PAGER's overall assessment of earthquakes losses and alerting for the likelihood of secondary impacts? We find that while 21.5% of fatal earthquakes have deaths due to secondary (non-shaking) causes, only rarely are secondary effects the main cause of fatalities. The recent 2004 Great Sumatra-Andaman Islands earthquake is a notable exception, with extraordinary losses due to tsunami. The potential for secondary hazards varies greatly, and systematically, due to regional geologic and geomorphic conditions. Based on our findings, we have built country-specific disclaimers for PAGER that address potential for each hazard (Earle et al., Proceedings of the 14th World Conference of the Earthquake Engineering, Beijing, China, 2008). We will now focus on ways to model casualties from secondary effects based on their relative importance as well as their general predictability. ?? Springer Science+Business Media B.V. 2009.

Experimental investigation of a multicylinder unmodified diesel engine performance, emission, and heat loss characteristics using different biodiesel blends: rollout of B10 in Malaysia.

PubMed

Abedin, M J; Masjuki, H H; Kalam, M A; Varman, M; Arbab, M I; Fattah, I M Rizwanul; Masum, B M

2014-01-01

This paper deals with the performance and emission analysis of a multicylinder diesel engine using biodiesel along with an in-depth analysis of the engine heat losses in different subsystems followed by the energy balance of all the energy flows from the engine. Energy balance analysis allows the designer to appraise the internal energy variations of a thermodynamic system as a function of ''energy flows" across the control volume as work or heat and also the enthalpies associated with the energy flows which are passing through these boundaries. Palm and coconut are the two most potential biodiesel feed stocks in this part of the world. The investigation was conducted in a four-cylinder diesel engine fuelled with 10% and 20% blends of palm and coconut biodiesels and compared with B5 at full load condition and in the speed range of 1000 to 4000 RPM. Among the all tested blends, palm blends seemed more promising in terms of engine performance, emission, and heat losses. The influence of heat losses on engine performance and emission has been discussed thoroughly in this paper.

Locomotor activity, core body temperature, and circadian rhythms in mice selected for high or low heat loss.

PubMed

Mousel, M R; Stroup, W W; Nielsen, M K

2001-04-01

Daily locomotor activity, core body temperature, and their circadian rhythms were measured in lines of mice selected for high (MH) or low (ML) heat loss and unselected controls (MC). Lines were created by selecting for 16 generations in each of three replicates. Collection of locomotor activity and core temperature data spanned Generations 20 and 21 for a total of 352 mice. Physical activity and core body temperature data were accumulated using implanted transmitters and continuous automated collection. Measurement for each animal was for 3 d. Activity was recorded for each half hour and then averaged for the day; temperature was averaged daily; circadian rhythm was expressed in 12-h (light vs dark) or 6-h periods as well as by fitting cyclic models. Activity means were transformed to log base 2 to lessen heterogeneity of variance within lines. Heat loss for a 15-h period beginning at 1630 and feed intake for 7 d were measured on 74 additional mice in order to estimate the relationship between locomotor activity and heat loss or feed intake. Selection lines were different (P < 0.01) for both locomotor activity and core body temperature. Differences were due to selection (MH-ML, P < 0.01), and there was no evidence of asymmetry of response (P > 0.38). Retransformed from log base 2 to the scale of measurement, mean activity counts were 308, 210, and 150 for MH, MC, and ML, respectively. Mean core temperatures were 37.2, 36.9, and 36.7 degrees C for MH, MC, and ML (P < 0.01), respectively. Females had greater physical activity (P < 0.01) and body temperature (P < 0.01) than males. There was no evidence of a sex x selection criterion interaction for either activity or temperature (P > 0.20). Overall phenotypic correlation between body temperature and log base 2 activity was 0.43 (P < 0.01). Periods during the day were different for both 12- and 6-h analyses (P < 0.01), but there were no period x selection criterion interactions (P > 0.1) for physical activity or body

Regeneration efficiency, shuttle heat loss and thermal conductivity in epoxy-composite annualr gap regenerators from 4K to 80K

NASA Technical Reports Server (NTRS)

Myrtle, K.; Cygax, S.; Plateel, C.; Winter, C.

1983-01-01

A test apparatus designed to simulate a section of a Stirling cycle cryocooler was built. Measurements of regeneration efficiency, shuttle heat loss and thermal conductivity reported for several regenerator test sections. The test composites were epoxy glass, epoxy glass with lead particles, epoxy glass with activated charcoal and epoxy graphite. Losses measured for these materials were approximately the same. Losses are in good agreement with those calculated theoretically for an epoxy glass (C-10) composite. The implications of these results on cryocooler design are discussed.

Three-dimensional quantitative analysis of adhesive remnants and enamel loss resulting from debonding orthodontic molar tubes.

PubMed

Janiszewska-Olszowska, Joanna; Tandecka, Katarzyna; Szatkiewicz, Tomasz; Sporniak-Tutak, Katarzyna; Grocholewicz, Katarzyna

2014-09-10

Presenting a new method for direct, quantitative analysis of enamel surface. Measurement of adhesive remnants and enamel loss resulting from debonding molar tubes. Buccal surfaces of fifteen extracted human molars were directly scanned with an optic blue-light 3D scanner to the nearest 2 μm. After 20 s etching molar tubes were bonded and after 24 h storing in 0.9% saline - debonded. Then 3D scanning was repeated. Superimposition and comparison were proceeded and shape alterations of the entire objects were analyzed using specialized computer software. Residual adhesive heights as well as enamel loss depths have been obtained for the entire buccal surfaces. Residual adhesive volume and enamel loss volume have been calculated for every tooth. The maximum height of adhesive remaining on enamel surface was 0.76 mm and the volume on particular teeth ranged from 0.047 mm3 to 4.16 mm3. The median adhesive remnant volume was 0.988 mm3. Mean depths of enamel loss for particular teeth ranged from 0.0076 mm to 0.0416 mm. Highest maximum depth of enamel loss was 0.207 mm. Median volume of enamel loss was 0.104 mm3 and maximum volume was 1.484 mm3. Blue-light 3D scanning is able to provide direct precise scans of the enamel surface, which can be superimposed in order to calculate shape alterations. Debonding molar tubes leaves a certain amount of adhesive remnants on the enamel, however the interface fracture pattern varies for particular teeth and areas of enamel loss are present as well.

Experimental Investigation of a Multicylinder Unmodified Diesel Engine Performance, Emission, and Heat Loss Characteristics Using Different Biodiesel Blends: Rollout of B10 in Malaysia

PubMed Central

Abedin, M. J.; Masjuki, H. H.; Kalam, M. A.; Varman, M.; Arbab, M. I.; Fattah, I. M. Rizwanul; Masum, B. M.

2014-01-01

This paper deals with the performance and emission analysis of a multicylinder diesel engine using biodiesel along with an in-depth analysis of the engine heat losses in different subsystems followed by the energy balance of all the energy flows from the engine. Energy balance analysis allows the designer to appraise the internal energy variations of a thermodynamic system as a function of ‘‘energy flows” across the control volume as work or heat and also the enthalpies associated with the energy flows which are passing through these boundaries. Palm and coconut are the two most potential biodiesel feed stocks in this part of the world. The investigation was conducted in a four-cylinder diesel engine fuelled with 10% and 20% blends of palm and coconut biodiesels and compared with B5 at full load condition and in the speed range of 1000 to 4000 RPM. Among the all tested blends, palm blends seemed more promising in terms of engine performance, emission, and heat losses. The influence of heat losses on engine performance and emission has been discussed thoroughly in this paper. PMID:25162046

NO formation in the burnout region of a partially premixed methane-air flame with upstream heat loss

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mokhov, A.V.; Levinsky, H.B.

Measurements of temperature and NO concentration in laminar, partially premixed methane-air flames stabilized on a ceramic burner in coflow are reported. The NO concentration and temperature were determined by laser-induced fluorescence (LIF) and coherent anti-Stokes Raman scattering (CARS), respectively. Upstream heat loss to the burner was varied by changing the exit velocity of the fuel-air mixture at a constant equivalence ratio of 1,3; this alters the structure of the flame from an axisymmetric Bunsen-type to a strongly stabilized flat flame. To facilitate analysis of the results, a method is derived for separating the effects of dilution from those of chemicalmore » reaction based on the relation between the measured temperature and the local mixture fraction, including the effects of upstream heat loss. Using this method, the amount of NO formed during burnout of the hot, fuel-rich combustion products can be ascertained. In the Bunsen-type flame, it is seen that {approximately}40 ppm of NO are produced in this burnout region, at temperatures between {approximately}2,100 K and {approximately}1,900 K, probably via the Zeldovich mechanism. Reducing the exit velocity of 12 cm/s reduces the flame temperature substantially, and effectively eliminates this contribution. At velocities of 12 and 8 cm/s, {approximately}10 ppm of NO are formed in the burnout region, even though the gas temperatures are too low for Zeldovich NO to be significant. Although the mechanism responsible for these observations is as yet unclear, the results are consistent with the idea that the low temperatures in the fuel-rich gases caused by upstream heat loss retard the conversion of HCN (formed via the Fenimore mechanism) to NO, with this residual HCN then being converted to NO during burnout.« less

Metabolism and evaporative heat loss in the dik-dik antelope (Rhynchotragus kirki).

PubMed

Kamau, J M

1988-01-01

1. Under controlled conditions, the rate of oxygen consumption (VO2) respiratory frequency, evaporative water loss, heat balance, rectal (Trec) and surface temperatures were determined in the dik-dik antelopes at ambient temperatures (Ta) ranging from 1 to 44 degrees C. 2. The thermal neutral zone was found to be between 24 and 35 degrees C. 3. Respiratory frequency ranged between 27 and 630 breaths/min. 4. At a Ta of 44 degrees C, 95% of the heat produced by the dik-dik was lost via respiratory evaporation. Despite an increase in Trec, cutaneous evaporation did not increase. 5. During panting, VO2 increased in accordance with the expected Q10 effect, contrary to earlier findings. 6. Measurements of circadian rhythm [LD 12:12 (7-19) CT26 degrees C] in VO2 showed that the minimum VO2 (0.42 ml O2/g/hr) occurred at midnight while the maximum (0.78 ml O2/g/hr) occurred at midday. The 24 hr mean VO2 was 0.61 ml O2/g/hr. 7. These measurements suggest that in nature, determinants other than light may be responsible for triggering the variations observed in VO2.

Resonance in fast-wave amplitude in the periphery of cylindrical plasmas and application to edge losses of wave heating power in tokamaks

DOE PAGES

Perkins, R. J.; Hosea, J. C.; Bertelli, N.; ...

2016-07-01

Heating magnetically confined plasmas using waves in the ion-cyclotron range of frequencies typically requires coupling these waves over a steep density gradient. Furthermore, this process has produced an unexpected and deleterious phenomenon on the National Spherical Torus eXperiment (NSTX): a prompt loss of wave power along magnetic field lines in front of the antenna to the divertor. Understanding this loss may be key to achieving effective heating and expanding the operational space of NSTX-Upgrade. Here, we propose that a new type of mode, which conducts a significant fraction of the total wave power in the low-density peripheral plasma, is drivingmore » these losses. We demonstrate the existence of such modes, which are distinct from surface modes and coaxial modes, in a cylindrical cold-plasma model when a half wavelength structure fits into the region outside the core plasma. The latter condition generalizes the previous hypothesis regarding the occurence of the edge losses and may explain why full-wave simulations predict these losses in some cases but not others. If valid, this condition implies that outer gap control is a potential strategy for mitigating the losses in NSTX-Upgrade in addition to raising the magnetic field or influencing the edge density.« less

Generation of a Parabolic Trough Collector Efficiency Curve from Separate Measurements of Outdoor Optical Efficiency and Indoor Receiver Heat Loss

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kutscher, C.; Burkholder, F.; Stynes, J. K.

2012-02-01

The thermal efficiency of a parabolic trough collector is a function of both the fraction of direct normal radiation absorbed by the receiver (the optical efficiency) and the heat lost to the environment when the receiver is at operating temperature. The thermal efficiency can be determined by testing the collector under actual operating conditions or by separately measuring these two components. This paper describes how outdoor measurement of the optical efficiency is combined with laboratory measurements of receiver heat loss to obtain the thermal efficiency curve. This paper describes this approach and also makes the case that there are advantagesmore » to plotting collector efficiency versus the difference between the operating temperature and the ambient temperature at which the receiver heat loss was measured divided by radiation to a fractional power (on the order of 1/3 but obtained via data regression) - as opposed to the difference between operating and ambient temperatures divided by the radiation. The results are shown to be robust over wide ranges of ambient temperature, sky temperature, and wind speed.« less

On the response of subduction in the South Pacific to an intensification of westerlies and heat flux in an eddy permitting ocean model

NASA Astrophysics Data System (ADS)

Liu, Chengyan; Wang, Zhaomin; Li, Bingrui; Cheng, Chen; Xia, Ruibin

2017-04-01

Based on an eddy permitting ocean general circulation model, the response of water masses to two distinct climate scenarios in the South Pacific is assessed in this paper. Under annually repeating atmospheric forcing that is characterized by different westerlies and associated heat flux, the response of Subantarctic Mode Water (SAMW) and Antarctic Intermediate Water (AAIW) is quantitatively estimated. Both SAMW and AAIW are found to be warmer, saltier and denser under intensified westerlies and increased heat loss. The increase in the subduction volume of SAMW and AAIW is about 19.8 Sv (1 Sv = 106 m3 s-1). The lateral induction term plays a dominant role in the changes in the subduction volume due to the deepening of the mixed layer depth (MLD). Furthermore, analysis of the buoyancy budget is used to quantitatively diagnose the reason for the changes in the MLD. The deepening of the MLD is found to be primarily caused by the strengthening of heat loss from the ocean to the atmosphere in the formation region of SAMW and AAIW.

Three-dimensional quantitative analysis of adhesive remnants and enamel loss resulting from debonding orthodontic molar tubes

PubMed Central

2014-01-01

Aims Presenting a new method for direct, quantitative analysis of enamel surface. Measurement of adhesive remnants and enamel loss resulting from debonding molar tubes. Material and methods Buccal surfaces of fifteen extracted human molars were directly scanned with an optic blue-light 3D scanner to the nearest 2 μm. After 20 s etching molar tubes were bonded and after 24 h storing in 0.9% saline - debonded. Then 3D scanning was repeated. Superimposition and comparison were proceeded and shape alterations of the entire objects were analyzed using specialized computer software. Residual adhesive heights as well as enamel loss depths have been obtained for the entire buccal surfaces. Residual adhesive volume and enamel loss volume have been calculated for every tooth. Results The maximum height of adhesive remaining on enamel surface was 0.76 mm and the volume on particular teeth ranged from 0.047 mm3 to 4.16 mm3. The median adhesive remnant volume was 0.988 mm3. Mean depths of enamel loss for particular teeth ranged from 0.0076 mm to 0.0416 mm. Highest maximum depth of enamel loss was 0.207 mm. Median volume of enamel loss was 0.104 mm3 and maximum volume was 1.484 mm3. Conclusions Blue-light 3D scanning is able to provide direct precise scans of the enamel surface, which can be superimposed in order to calculate shape alterations. Debonding molar tubes leaves a certain amount of adhesive remnants on the enamel, however the interface fracture pattern varies for particular teeth and areas of enamel loss are present as well. PMID:25208969

Quantitative psychomotor dysfunction in schizophrenia: a loss of drive, impaired movement execution or both?

PubMed

Docx, Lise; Sabbe, Bernard; Provinciael, Pieter; Merckx, Niel; Morrens, Manuel

2013-01-01

The aim of the present study was to investigate the predictive value of qualitative psychomotor performance levels and subaspects of the negative syndrome for quantitative motor activity levels in patients with schizophrenia. Twenty-seven stabilized patients with schizophrenia and 22 age- and sex-matched healthy controls were included in the study. An extensive battery of psychomotor performance tests (Finger Tapping Test, Purdue Pegboard Test, Line Copying Test, Neurological Evaluation Scale, Salpêtrière Retardation Rating Scale), clinical rating scales (Positive and Negative Syndrome Scale) and 24-hour actigraphy were administered to all participants. Correlational analyses showed that motor activity levels were associated with avolition as well as clinically assessed psychomotor slowing. However, in a regression model, only avolition was found to be a significant predictor for motor activity levels in patients with schizophrenia; none of the psychomotor performance tests nor the severity of emotional expressivity deficits contributed to the model. Qualitative and quantitative psychomotor deficits seem to be independent phenomena in stabilized patients with schizophrenia. The diminishing in motor activity in patients with schizophrenia is related to a loss of drive and not to problems in the quality of movement execution. © 2013 S. Karger AG, Basel.

Quantitation of tissue loss during prolonged space flight

NASA Technical Reports Server (NTRS)

Leonard, J. I.; Leach, C. S.; Rambaut, P. C.

1983-01-01

An analysis of data from the three Skylab missions was performed to assess the lean body mass (LBM) and fat components of inflight body weight loss. Six methods for determining LBM were employed based on changes in total body water, total body potassium, nitrogen balance, potassium balance, and stereophotometric-body density. Those based solely on body potassium, and potassium and nitrogen balances (when expressed as shifts from preflight control), consistently overestimated LBM loss unless appropriate corrections were made. The average results from the various methods indicated that of a mean inflight total body weight loss of 2.7 + or - 0.3 kg (SD) for all nine crewmembers, more than half (1.5 + or - 0.3 kg) can be attributed to loss of LBM (including 1.1 kg body water), the remainder (1.2 + or - 0.3 kg) being derived from fat stores. The reduction of LBM appeared to be complete after the first month of flight and thereafter was largely independent of mission duration, diet, and exercise.

Visual investigation on the heat dissipation process of a heat sink by using digital holographic interferometry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wu, Bingjing; Zhao, Jianlin, E-mail: jlzhao@nwpu.edu.cn; Wang, Jun

2013-11-21

We present a method for visually and quantitatively investigating the heat dissipation process of plate-fin heat sinks by using digital holographic interferometry. A series of phase change maps reflecting the temperature distribution and variation trend of the air field surrounding heat sink during the heat dissipation process are numerically reconstructed based on double-exposure holographic interferometry. According to the phase unwrapping algorithm and the derived relationship between temperature and phase change of the detection beam, the full-field temperature distributions are quantitatively obtained with a reasonably high measurement accuracy. And then the impact of heat sink's channel width on the heat dissipationmore » performance in the case of natural convection is analyzed. In addition, a comparison between simulation and experiment results is given to verify the reliability of this method. The experiment results certify the feasibility and validity of the presented method in full-field, dynamical, and quantitative measurement of the air field temperature distribution, which provides a basis for analyzing the heat dissipation performance of plate-fin heat sinks.« less

A new technique for quantitative analysis of hair loss in mice using grayscale analysis.

PubMed

Ponnapakkam, Tulasi; Katikaneni, Ranjitha; Gulati, Rohan; Gensure, Robert

2015-03-09

Alopecia is a common form of hair loss which can occur in many different conditions, including male-pattern hair loss, polycystic ovarian syndrome, and alopecia areata. Alopecia can also occur as a side effect of chemotherapy in cancer patients. In this study, our goal was to develop a consistent and reliable method to quantify hair loss in mice, which will allow investigators to accurately assess and compare new therapeutic approaches for these various forms of alopecia. The method utilizes a standard gel imager to obtain and process images of mice, measuring the light absorption, which occurs in rough proportion to the amount of black (or gray) hair on the mouse. Data that has been quantified in this fashion can then be analyzed using standard statistical techniques (i.e., ANOVA, T-test). This methodology was tested in mouse models of chemotherapy-induced alopecia, alopecia areata and alopecia from waxing. In this report, the detailed protocol is presented for performing these measurements, including validation data from C57BL/6 and C3H/HeJ strains of mice. This new technique offers a number of advantages, including relative simplicity of application, reliance on equipment which is readily available in most research laboratories, and applying an objective, quantitative assessment which is more robust than subjective evaluations. Improvements in quantification of hair growth in mice will improve study of alopecia models and facilitate evaluation of promising new therapies in preclinical studies.

Influence of heating on the weight loss and mineral phase in MSWI ash: LOI of incineration ash

NASA Astrophysics Data System (ADS)

Yang, Shuo

2017-04-01

Loss on ignition (LOI) is a very common method for estimating the volatile species in solid sample. Normally, the measurement of LOI can be convenient and accurate, but for municipal solid waste incineration (MSWI) ash, the process may become intricate due to the complexity of the sample. In the incineration ash, there exist various phases, such as mineral, metal, organic and glass. The reaction and transformation of some materials during heating will influence the measurement. 5 incineration ash samples were selected and tested in this study. LOI content was basically measured at high (850°C) and relatively low (440°C) temperatures. The comparison between these two measurements showed a large difference. X-ray diffraction (XRD) and thermal analysis (TG-DTA) were carried out to investigate the mineral changes and weight losses with different ignition temperatures. The mineralogical analysis suggests that the decomposition of hydrate and carbonate phases cannot be neglected for LOI measurement of incineration. A long-time heating under relatively lower temperature (400∼450°C) compared with soil sample measurement (≥500°C) was recommended by this study.

Influence of body mass loss on changes in heart rate during exercise in the heat: a systematic review.

PubMed

Adams, William M; Ferraro, Elizabeth M; Huggins, Robert A; Casa, Douglas J

2014-08-01

The purpose of this review was to compare the changes in heart rate (HR) for every 1% change in body mass loss (ΔBML) in individuals while exercising in the heat. PubMed, SPORTDiscus, ERIC, CINAHL, and Scopus were searched from the earliest entry to February 2013 using the search terms dehydration, heart rate, and exercise in various combinations. Original research articles that met the following criteria were included: (a) valid measure of HR, (b) exercise in the heat (>26.5° C [79.7 °F]), (c) the level of dehydration reached at least 2%, (d) a between-group comparison (a euhydrated group or a graded dehydration protocol) was evident, and (e) for rehydration protocols, only oral rehydration was considered for inclusion. Twenty articles were included in the final analysis. Mean values and SDs for HR and percentage of body mass loss immediately after exercise were used for this review. The mean change in HR for every 1% ΔBML was 3 b·min-1. In trials where subjects arrived euhydrated and hypohydrated, the mean change in HR for every 1% ΔBML was 3 and 3 b·min-1, respectively. Fixed intensity and variable intensity trials exhibited a mean HR change of 4 and 1 b·min-1, respectively. Exercising in the heat while hypohydrated (≥2%) resulted in an increased HR after exercise. This increase in HR for every 1% ΔBML exacerbates cardiovascular strain in exercising individuals, thus causing decrements in performance. It should be encouraged that individuals should maintain an adequate level of hydration to maximize performance, especially in the heat.

Radiative Heat Loss Measurements During Microgravity Droplet Combustion in a Slow Convective Flow

NASA Technical Reports Server (NTRS)

Hicks, Michael C.; Kaib, Nathan; Easton, John; Nayagam, Vedha; Williams, Forman A.

2003-01-01

Radiative heat loss from burning droplets in a slow convective flow under microgravity conditions is measured using a broad-band (0.6 to 40 microns) radiometer. In addition, backlit images of the droplet as well as color images of the flame were obtained using CCD cameras to estimate the burning rates and the flame dimensions, respectively. Tests were carried out in air at atmospheric pressure using n-heptane and methanol fuels with imposed forced flow velocities varied from 0 to 10 centimeters per second and initial droplet diameters varied from 1 to 3 millimeters. Slow convective flows were generated using three different experimental configurations in three different facilities in preparation for the proposed International Space Station droplet experiments. In the 2.2 Second Drop-Tower Facility a droplet supported on the leading edge of a quartz fiber is placed within a flow tunnel supplied by compressed air. In the Zero-Gravity Facility (five-second drop tower) a tethered droplet is translated in a quiescent ambient atmosphere to establish a uniform flow field around the droplet. In the KC 135 aircraft an electric fan was used to draw a uniform flow past a tethered droplet. Experimental results show that the burn rate increases and the overall flame size decreases with increases in forced-flow velocities over the range of flow velocities and droplet sizes tested. The total radiative heat loss rate, Q(sub r), decreases as the imposed flow velocity increases with the spherically symmetric combustion having the highest values. These observations are in contrast to the trends observed for gas-jet flames in microgravity, but consistent with the observations during flame spread over solid fuels where the burning rate is coupled to the forced flow as here.

Allocation of Load-Loss Cost Caused by Voltage Sag

NASA Astrophysics Data System (ADS)

Gao, X.

2017-10-01

This paper focuses on the allocation of load-loss cost caused by voltage sag in the environment of electricity market. To compensate the loss of loads due to voltage sags, the load-loss cost is allocated to both sources and power consumers. On the basis of Load Drop Cost (LDC), a quantitative evaluation index of load-loss cost caused by voltage sag is identified. The load-loss cost to be allocated to power consumers themselves is calculated according to load classification. Based on the theory of power component the quantitative relation between sources and loads is established, thereby a quantitative calculation method for load-loss cost allocated to each source is deduced and the quantitative compensation from individual source to load is proposed. A simple five-bus system illustrates the main features of the proposed method.

Quantitation of tissue loss during prolonged space flight

NASA Technical Reports Server (NTRS)

Leonard, J. I.

1979-01-01

Data from Skylab missions related to tissue loss in space were analyzed. Significant changes in gross body composition occur during spaceflight, these include: alterations in water balance resulting from headward shifts of fluid, loss of musculoskeletal tissue, and alterations in fat depending upon the balance between caloric intake and energy expenditure. An effort was made to control the more essential components of body weight on the Skylab missions.

Comparative efficacy of five long-term weight loss drugs: quantitative information for medication guidelines.

PubMed

Dong, Z; Xu, L; Liu, H; Lv, Y; Zheng, Q; Li, L

2017-12-01

Quantitative information is scarce in current obesity medication guidelines, and they do not clearly reflect the differences in the efficacy characteristics among various drugs. This study quantitatively assessed the efficacy characteristics of five FDA-approved long-term weight loss drugs. Potentially eligible studies were obtained from public databases. Using the differences in the weight change from baseline between the drug group and the corresponding placebo group as the major indicator of efficacy, a time-effect model was established, and crucial pharmacodynamic parameters, such as the maximal efficacy, drug onset time and rate of body weight regain after the maximal efficacy point, were used to reflect the differences in efficacy among the five drugs. Finally, 50 reports (involving 43,443 participants) were included. After deducting the placebo effects, the maximal efficacies (95% CI) of orlistat (120 mg), lorcaserin, naltrexone-bupropion, phentermine-topiramate (PT, 7.5/46 mg) and liraglutide were -2.94 (-5.82, -1.27), -3.06 (-4.39, -1.71), -6.15 (-9.78, -3.25), -7.45 (-9.76, -3.88) and -5.50 (-10.62, -2.97) kg at weeks 60, 54, 67, 59 and 65 respectively, and their rates of body weight regain were 0.51, 0.48, 0.91, 1.27and 0.43 kg per year respectively. The 1-year dropout rates of orlistat, lorcaserin, naltrexone-bupropion, PT and liraglutide were 29.0, 40.9, 49.1, 34.9 and 24.3% respectively. In addition, a significant dose-effect correlation was observed for orlistat and PT. This study provides valid quantitative information for medication guidelines. © 2017 World Obesity Federation.

Quantitative analysis of interfacial chemistry in TiC/Ti composite using electron-energy-loss spectroscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gu, M.; Jiang, W.; Zhang, G.

Due to titanium carbide`s physical and elastic properties, titanium carbide particles are widely used as a reinforcement in titanium-alloy-based composites. Previous studies have shown that no obvious reaction products were detected on the interface region in TiC/Ti alloy systems; instead, a nonstoichiometric region in the TiC particle between the Ti{sub 6}Al{sub 4}V alloy and the stoichiometric TiC was found. However, the nature and the extent of the nonstoichiometric zone have not been quantitatively described. The present communication reports some results of a parallel electron-energy-loss spectroscopy (PEELS) study on a 10 vol pct TiC-particle-reinforced IMI-829 metal-matrix composite.

Toward a Better Quantitative Understanding of Polar Stratospheric Ozone Loss

NASA Technical Reports Server (NTRS)

Frieler, K.; Rex, M.; Salawitch, R. J.; Canty, T.; Streibel, M.; Stimpfle, R. M.; Pfeilsticker, K.; Dorf, M.; Weisenstein, D. K.; Godin-Beekmann, S.

2006-01-01

Previous studies have shown that observed large O3 loss rates in cold Arctic Januaries cannot be explained with current understanding of the loss processes, recommended reaction kinetics, and standard assumptions about total stratospheric chlorine and bromine. Studies based on data collected during recent field campaigns suggest faster rates of photolysis and thermal decomposition of ClOOCl and higher stratospheric bromine concentrations than previously assumed. We show that a model accounting for these kinetic changes and higher levels of BrO can largely resolve the January Arctic O3 loss problem and closely reproduces observed Arctic O3 loss while being consistent with observed levels of ClO and ClOOCl. The model also suggests that bromine catalyzed O3 loss is more important relative to chlorine catalyzed loss than previously thought.

Infrared thermal imaging as a method to evaluate heat loss in newborn lambs.

PubMed

Labeur, L; Villiers, G; Small, A H; Hinch, G N; Schmoelzl, S

2017-12-01

Thermal imaging technology has been identified as a potential method for non-invasive study of thermogenesis in the neonatal lamb. In comparison to measurement of the core body temperature, infrared thermography may observe thermal loss and thermogenesis linked to subcutaneous brown fat depots. This study aimed to identify a suitable method to measure heat loss in the neonatal lamb under a cold challenge. During late pregnancy (day 125), ewes were subjected to either shearing (n=15) or mock handling (sham-shorn for 2min mimicking the shearing movements) (n=15). Previous studies have shown an increase in brown adipose tissue deposition in lambs born to ewes shorn during pregnancy and we hypothesized that the shearing treatment would impact thermoregulatory capacities in newborn lambs. Lambs born to control ewes (n=14; CONTROL) and shorn ewes (n=13; SHORN) were subjected to a cold challenge of 1h duration at 4h after birth. During the cold challenge, thermography images were taken every 10min, from above, at a fixed distance from the dorsal midline. On each image, four fixed-size areas were identified (shoulder, mid loin, hips and rump) and the average and maximum temperatures of each recorded. In all lambs, body surface temperature decreased over time. Overall the SHORN lambs appeared to maintain body surface temperature better than CONTROL lambs, while CONTROL lambs appeared to have higher core temperature. At 30min post cold challenge SHORN lambs tended to have higher body surface temperatures than lambs (P=0.0474). Both average and maximum temperatures were highest at the hips. Average temperature was lowest at the shoulder (P<0.05), while maximum temperatures were lowest at both shoulder and rump (P<0.005). These results indicate that lambs born to shorn ewes maintained their radiated body surface temperature better than CONTROL lambs. In conjunction with core temperature changes under cold challenge, this insight will allow us to understand whether increased

Whole-body heat exchange during heat acclimation and its decay.

PubMed

Poirier, Martin P; Gagnon, Daniel; Friesen, Brian J; Hardcastle, Stephen G; Kenny, Glen P

2015-02-01

The purpose of this study was to quantify how much whole-body heat loss increases during heat acclimation and the decay in these improvements after heat acclimation. Ten males underwent a 14-d heat acclimation protocol that consisted of 90 min of cycling in the heat (40°C, 20% relative humidity) at approximately 50% of maximum oxygen consumption. Before (day 0), during (day 7), and at the end (day 14) of the heat acclimation protocol as well as 7 and 14 d after heat acclimation (days 21 and 28), whole-body heat exchange (evaporative and dry) was measured using direct calorimetry during three bouts of 30-min exercise at 300 (Ex1), 350 (Ex2), and 400 W·m (Ex3), each separated by 10 and 20 min of recovery, respectively, at 35°C and 16% relative humidity. Concurrent measurements of metabolic heat production (indirect calorimetry) allowed for the direct calculation of change in body heat content (ΔHb). After accounting for an increase in net dry heat gain, increases in whole-body evaporative heat loss were evident for Ex2 and Ex3 on day 7 (Ex2, 4.9 ± 5.6%; Ex3, 9.0 ± 6.0%; both P ≤ 0.05) and all heat loads on day 14 (Ex1, 7.6 ± 8.3%; Ex2, 7.7 ± 5.5%; Ex3, 11.2 ± 4.6%; all P ≤ 0.05) relative to day 0 (Ex1, 494 ± 27 W; Ex2, 583 ± 21 W; Ex3, 622 ± 36 W). As a result, a lower cumulative ΔHb was measured on day 7 (-18 ± 8%, P ≤ 0.001) and day 14 (-26 ± 10%, P ≤ 0.001) compared with that measured on day 0 (1062 ± 123 kJ). Most of these improvements were retained after 2 wk of nonexposure to the heat. This is the first study to quantify how much 14 d of heat acclimation can increase whole-body evaporative heat loss, which can improve by as much as approximately 11%.

Bifurcation and extinction limit of stretched premixed flames with chain-branching intermediate kinetics and radiative loss

NASA Astrophysics Data System (ADS)

Zhang, Huangwei; Chen, Zheng

2018-05-01

Premixed counterflow flames with thermally sensitive intermediate kinetics and radiation heat loss are analysed within the framework of large activation energy. Unlike previous studies considering one-step global reaction, two-step chemistry consisting of a chain branching reaction and a recombination reaction is considered here. The correlation between the flame front location and stretch rate is derived. Based on this correlation, the extinction limit and bifurcation characteristics of the strained premixed flame are studied, and the effects of fuel and radical Lewis numbers as well as radiation heat loss are examined. Different flame regimes and their extinction characteristics can be predicted by the present theory. It is found that fuel Lewis number affects the flame bifurcation qualitatively and quantitatively, whereas radical Lewis number only has a quantitative influence. Stretch rates at the stretch and radiation extinction limits respectively decrease and increase with fuel Lewis number before the flammability limit is reached, while the radical Lewis number shows the opposite tendency. In addition, the relation between the standard flammability limit and the limit derived from the strained near stagnation flame is affected by the fuel Lewis number, but not by the radical Lewis number. Meanwhile, the flammability limit increases with decreased fuel Lewis number, but with increased radical Lewis number. Radical behaviours at flame front corresponding to flame bifurcation and extinction are also analysed in this work. It is shown that radical concentration at the flame front, under extinction stretch rate condition, increases with radical Lewis number but decreases with fuel Lewis number. It decreases with increased radiation loss.

Estimating population heat exposure and impacts on working people in conjunction with climate change.

PubMed

Kjellstrom, Tord; Freyberg, Chris; Lemke, Bruno; Otto, Matthias; Briggs, David

2018-03-01

Increased environmental heat levels as a result of climate change present a major challenge to the health, wellbeing and sustainability of human communities in already hot parts of this planet. This challenge has many facets from direct clinical health effects of daily heat exposure to indirect effects related to poor air quality, poor access to safe drinking water, poor access to nutritious and safe food and inadequate protection from disease vectors and environmental toxic chemicals. The increasing environmental heat is a threat to environmental sustainability. In addition, social conditions can be undermined by the negative effects of increased heat on daily work and life activities and on local cultural practices. The methodology we describe can be used to produce quantitative estimates of the impacts of climate change on work activities in countries and local communities. We show in maps the increasing heat exposures in the shade expressed as the occupational heat stress index Wet Bulb Globe Temperature. Some tropical and sub-tropical areas already experience serious heat stress, and the continuing heating will substantially reduce work capacity and labour productivity in widening parts of the world. Southern parts of Europe and the USA will also be affected. Even the lowest target for climate change (average global temperature change = 1.5 °C at representative concentration pathway (RCP2.6) will increase the loss of daylight work hour output due to heat in many tropical areas from less than 2% now up to more than 6% at the end of the century. A global temperature change of 2.7 °C (at RCP6.0) will double this annual heat impact on work in such areas. Calculations of this type of heat impact at country level show that in the USA, the loss of work capacity in moderate level work in the shade will increase from 0.17% now to more than 1.3% at the end of the century based on the 2.7 °C temperature change. The impact is naturally mainly occurring in the

Estimating population heat exposure and impacts on working people in conjunction with climate change

NASA Astrophysics Data System (ADS)

Kjellstrom, Tord; Freyberg, Chris; Lemke, Bruno; Otto, Matthias; Briggs, David

2018-03-01

Increased environmental heat levels as a result of climate change present a major challenge to the health, wellbeing and sustainability of human communities in already hot parts of this planet. This challenge has many facets from direct clinical health effects of daily heat exposure to indirect effects related to poor air quality, poor access to safe drinking water, poor access to nutritious and safe food and inadequate protection from disease vectors and environmental toxic chemicals. The increasing environmental heat is a threat to environmental sustainability. In addition, social conditions can be undermined by the negative effects of increased heat on daily work and life activities and on local cultural practices. The methodology we describe can be used to produce quantitative estimates of the impacts of climate change on work activities in countries and local communities. We show in maps the increasing heat exposures in the shade expressed as the occupational heat stress index Wet Bulb Globe Temperature. Some tropical and sub-tropical areas already experience serious heat stress, and the continuing heating will substantially reduce work capacity and labour productivity in widening parts of the world. Southern parts of Europe and the USA will also be affected. Even the lowest target for climate change (average global temperature change = 1.5 °C at representative concentration pathway (RCP2.6) will increase the loss of daylight work hour output due to heat in many tropical areas from less than 2% now up to more than 6% at the end of the century. A global temperature change of 2.7 °C (at RCP6.0) will double this annual heat impact on work in such areas. Calculations of this type of heat impact at country level show that in the USA, the loss of work capacity in moderate level work in the shade will increase from 0.17% now to more than 1.3% at the end of the century based on the 2.7 °C temperature change. The impact is naturally mainly occurring in the southern

The Scaling of Performance and Losses in Miniature Internal Combustion Engines

DTIC Science & Technology

2010-01-01

reliable measurements of engine performance and losses in these small engines. Methodologies are also developed for measuring volumetric, heat transfer...making reliable measurements of engine performance and losses in these small engines. Methodologies are also developed for measuring volumetric, heat ...the most important challenge as it accounts for 60-70% of total energy losses. Combustion losses are followed in order of importance by heat transfer

The heat rate index indicator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lasasso, M.; Runyan, B.; Napoli, J.

1995-06-01

This paper describes a method of tracking unit performance through the use of a reference number called the Heat Rate Index Indicator. The ABB Power Plant Controls OTIS performance monitor is used to determine when steady load conditions exist and then to collect controllable and equipment loss data which significantly impact thermal efficiency. By comparing these loss parameters to those found during the previous heat balance, it is possible to develop a new adjusted heat rate curve. These impacts on heat rate are used to changes the shape of the tested heat rate curve by the appropriate percentages over amore » specified load range. Mathcad is used to determine the Heat Rate Index by integrating for the areas beneath the adjusted heat rate curve and a heat rate curve that represents the unit`s ideal heat rate curve is the Heat Rate Index. An index of 1.0 indicates that the unit is operating at an ideal efficiency, while an index of less than 1.0 indicates that the unit is operating at less than ideal conditions. A one per cent change in the Heat Rate Index is equivalent to a one percent change in heat rate. The new shape of the adjusted heat rate curve and the individual curves generated from the controllable and equipment loss parameters are useful for determining performance problems in specific load ranges.« less

Air-induction aspirator-aerators cut heat loss to the atmosphere

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hodel, A.E.

1993-04-01

The efficiency of biological treatment at the Amoco Chemical's Cedar Bayou plant's activated-sludge wastewater-treatment system was reduced when outdoor temperatures fell below 65[degrees]F. Amoco experienced microbe fragmenting and failure to settle in final clarification, especially during winter. Meeting permit standards during winter was a concern. With mechanical aerators, water is pumped upward and thrown into the air. Much heat loss in the aerated basin was from evaporation and conduction of the mechanical aerator spray. The plant's wastewater staff decided to replace the aerators with subsurface, propeller-type aerator-mixers. These air-induction, aspirating aerator-mixers employ a system that eliminates the spray action throughmore » which evaporation and conduction can occur. The aspirator-aeration systems also have saved energy. The units do not have to overcome the forces of gravity, as with mechanical, surface splasher aerators, which required more horsepower and higher energy consumption to throw the water up into the air. The new units can be conveniently turned on and off to match a fluctuating flow. Since the Cedar Bayou plant installed the system, the aspirator-aerators' subsurface mixing capabilities have made winter permit compliance a steadfast routine.« less

Development of two stable isotope dilution assays for the quantitation of acrolein in heat-processed fats.

PubMed

Ewert, Alice; Granvogl, Michael; Schieberle, Peter

2011-04-27

Two stable isotope dilution assays were developed for the quantitation of acrolein in fats and oils using [(13)C(3)]-acrolein as the internal standard. First, a direct GC-MS headspace method, followed by an indirect GC-MS method using derivatization with pentafluorophenyl hydrazine, was established. Analysis of six different types of oils varying in their pattern of fatty acids showed significant differences in the amounts of acrolein formed after heating at various temperatures and for various times. For example, after 24 h at 140 °C, coconut oil contained 6.7 mg/kg, whereas linseed oil was highest with 242.3 mg/kg. A comparison of the results showed that the extent of acrolein formation seemed to be correlated with the amount of linolenic acid in the oils. Although the acrolein concentrations were lowered in all six oils after frying of potato crisps, linseed and rapeseed oil still contained the highest amounts of acrolein after frying. By applying both methods on different thermally treated fats and oils, nearly identical quantitative data were obtained.

A convenient method for the quantitative determination of elemental sulfur in coal by HPLC analysis of perchloroethylene extracts

USGS Publications Warehouse

Buchanan, D.H.; Coombs, K.J.; Murphy, P.M.; Chaven, C.

1993-01-01

A convenient method for the quantitative determination of elemental sulfur in coal is described. Elemental sulfur is extracted from the coal with hot perchloroethylene (PCE) (tetrachloroethene, C2Cl4) and quantitatively determined by HPLC analysis on a C18 reverse-phase column using UV detection. Calibration solutions were prepared from sublimed sulfur. Results of quantitative HPLC analyses agreed with those of a chemical/spectroscopic analysis. The HPLC method was found to be linear over the concentration range of 6 ?? 10-4 to 2 ?? 10-2 g/L. The lower detection limit was 4 ?? 10-4 g/L, which for a coal sample of 20 g is equivalent to 0.0006% by weight of coal. Since elemental sulfur is known to react slowly with hydrocarbons at the temperature of boiling PCE, standard solutions of sulfur in PCE were heated with coals from the Argonne Premium Coal Sample program. Pseudo-first-order uptake of sulfur by the coals was observed over several weeks of heating. For the Illinois No. 6 premium coal, the rate constant for sulfur uptake was 9.7 ?? 10-7 s-1, too small for retrograde reactions between solubilized sulfur and coal to cause a significant loss in elemental sulfur isolated during the analytical extraction. No elemental sulfur was produced when the following pure compounds were heated to reflux in PCE for up to 1 week: benzyl sulfide, octyl sulfide, thiane, thiophene, benzothiophene, dibenzothiophene, sulfuric acid, or ferrous sulfate. A sluury of mineral pyrite in PCE contained elemental sulfur which increased in concentration with heating time. ?? 1993 American Chemical Society.

A High Resolution/Accurate Mass (HRAM) Data-Dependent MS3 Neutral Loss Screening, Classification, and Relative Quantitation Methodology for Carbonyl Compounds in Saliva

NASA Astrophysics Data System (ADS)

Dator, Romel; Carrà, Andrea; Maertens, Laura; Guidolin, Valeria; Villalta, Peter W.; Balbo, Silvia

2017-04-01

Reactive carbonyl compounds (RCCs) are ubiquitous in the environment and are generated endogenously as a result of various physiological and pathological processes. These compounds can react with biological molecules inducing deleterious processes believed to be at the basis of their toxic effects. Several of these compounds are implicated in neurotoxic processes, aging disorders, and cancer. Therefore, a method characterizing exposures to these chemicals will provide insights into how they may influence overall health and contribute to disease pathogenesis. Here, we have developed a high resolution accurate mass (HRAM) screening strategy allowing simultaneous identification and relative quantitation of DNPH-derivatized carbonyls in human biological fluids. The screening strategy involves the diagnostic neutral loss of hydroxyl radical triggering MS3 fragmentation, which is only observed in positive ionization mode of DNPH-derivatized carbonyls. Unique fragmentation pathways were used to develop a classification scheme for characterizing known and unanticipated/unknown carbonyl compounds present in saliva. Furthermore, a relative quantitation strategy was implemented to assess variations in the levels of carbonyl compounds before and after exposure using deuterated d 3 -DNPH. This relative quantitation method was tested on human samples before and after exposure to specific amounts of alcohol. The nano-electrospray ionization (nano-ESI) in positive mode afforded excellent sensitivity with detection limits on-column in the high-attomole levels. To the best of our knowledge, this is the first report of a method using HRAM neutral loss screening of carbonyl compounds. In addition, the method allows simultaneous characterization and relative quantitation of DNPH-derivatized compounds using nano-ESI in positive mode.

Natural convection heat transfer coefficient for newborn baby - Thermal manikin assessed convective heat loses

NASA Astrophysics Data System (ADS)

Ostrowski, Ziemowit; Rojczyk, Marek

2017-11-01

The energy balance and heat exchange for newborn baby in radiant warmer environment are considered. The present study was performed to assess the body dry heat loss from an infant in radiant warmer, using copper cast anthropomorphic thermal manikin and controlled climate chamber laboratory setup. The total body dry heat losses were measured for varying manikin surface temperatures (nine levels between 32.5 °C and 40.1 °C) and ambient air temperatures (five levels between 23.5 °C and 29.7 °C). Radiant heat losses were estimated based on measured climate chamber wall temperatures. After subtracting radiant part, resulting convective heat loses were compared with computed ones (based on Nu correlations for common geometries). Simplified geometry of newborn baby was represented as: (a) single cylinder and (b) weighted sum of 5 cylinders and sphere. The predicted values are significantly overestimated relative to measured ones by: 28.8% (SD 23.5%) for (a) and 40.9% (SD 25.2%) for (b). This showed that use of adopted general purpose correlations for approximation of convective heat losses of newborn baby can lead to substantial errors. Hence, new Nu number correlating equation is proposed. The mean error introduced by proposed correlation was reduced to 1.4% (SD 11.97%), i.e. no significant overestimation. The thermal manikin appears to provide a precise method for the noninvasive assessment of thermal conditions in neonatal care.

Calculation of prompt loss and toroidal field ripple loss under neutral beam injection on EAST

NASA Astrophysics Data System (ADS)

Wu, Bin; Hao, Baolong; White, Roscoe; Wang, Jinfang; Zang, Qing; Han, Xiaofeng; Hu, Chundong

2017-02-01

Neutral beam injection is a major auxiliary heating method in the EAST experimental campaign. This paper gives detailed calculations of beam loss with different plasma equilibria using the guiding center code ORBIT and NUBEAM/TRANSP. Increasing plasma current can dramatically lower the beam ion prompt loss and ripple loss. Countercurrent beam injection gives a much larger prompt loss fraction than co-injection, and ripple-induced collisionless stochastic diffusion is the dominant loss channel.

Calculation of prompt loss and toroidal field ripple loss under neutral beam injection on EAST

DOE PAGES

Wu, Bin; Hao, Baolong; White, Roscoe; ...

2016-12-09

Here, neutral beam injection is a major auxiliary heating method in the EAST experimental campaign. This paper gives detailed calculations of beam loss with different plasma equilibria using the guiding center code ORBIT and NUBEAM/TRANSP. Increasing plasma current can dramatically lower the beam ion prompt loss and ripple loss. Countercurrent beam injection gives a much larger prompt loss fraction than co-injection, and ripple-induced collisionless stochastic diffusion is the dominant loss channel.

Calculation of prompt loss and toroidal field ripple loss under neutral beam injection on EAST

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wu, Bin; Hao, Baolong; White, Roscoe

Here, neutral beam injection is a major auxiliary heating method in the EAST experimental campaign. This paper gives detailed calculations of beam loss with different plasma equilibria using the guiding center code ORBIT and NUBEAM/TRANSP. Increasing plasma current can dramatically lower the beam ion prompt loss and ripple loss. Countercurrent beam injection gives a much larger prompt loss fraction than co-injection, and ripple-induced collisionless stochastic diffusion is the dominant loss channel.

Heat pipe cooled power magnetics

NASA Technical Reports Server (NTRS)

Chester, M. S.

1979-01-01

A high frequency, high power, low specific weight (0.57 kg/kW) transformer developed for space use was redesigned with heat pipe cooling allowing both a reduction in weight and a lower internal temperature rise. The specific weight of the heat pipe cooled transformer was reduced to 0.4 kg/kW and the highest winding temperature rise was reduced from 40 C to 20 C in spite of 10 watts additional loss. The design loss/weight tradeoff was 18 W/kg. Additionally, allowing the same 40 C winding temperature rise as in the original design, the KVA rating is increased to 4.2 KVA, demonstrating a specific weight of 0.28 kg/kW with the internal loss increased by 50W. This space environment tested heat pipe cooled design performed as well electrically as the original conventional design, thus demonstrating the advantages of heat pipes integrated into a high power, high voltage magnetic. Another heat pipe cooled magnetic, a 3.7 kW, 20A input filter inductor was designed, developed, built, tested, and described. The heat pipe cooled magnetics are designed to be Earth operated in any orientation.

Comparative study of beam losses and heat loads reduction methods in MITICA beam source

NASA Astrophysics Data System (ADS)

Sartori, E.; Agostinetti, P.; Dal Bello, S.; Marcuzzi, D.; Serianni, G.; Sonato, P.; Veltri, P.

2014-02-01

In negative ion electrostatic accelerators a considerable fraction of extracted ions is lost by collision processes causing efficiency loss and heat deposition over the components. Stripping is proportional to the local density of gas, which is steadily injected in the plasma source; its pumping from the extraction and acceleration stages is a key functionality for the prototype of the ITER Neutral Beam Injector, and it can be simulated with the 3D code AVOCADO. Different geometric solutions were tested aiming at the reduction of the gas density. The parameter space considered is limited by constraints given by optics, aiming, voltage holding, beam uniformity, and mechanical feasibility. The guidelines of the optimization process are presented together with the proposed solutions and the results of numerical simulations.

Forced heat loss from body surface reduces heat flow to body surface.

PubMed

Berman, A

2010-01-01

Heat stress is commonly relieved by forced evaporation from body surfaces. The mode of heat stress relief by heat extraction from the periphery is not clear, although it reduces rectal temperature. Radiant surface temperature (Ts) of the right half of the body surface was examined by thermovision in 4 lactating Holstein cows (30 kg of milk/d) during 7 repeated cycles of forced evaporation created by 30s of wetting followed by 4.5 min of forced airflow. Wetting was performed by an array of sprinklers (0.76 m(3)/h), and forced airflow (>3m/s velocity) over the right side of the body surface was produced by fans mounted at a height of 3m above the ground. Sprinkling wetted the hind legs, rump, and chest, but not the lower abdomen side, front legs, or neck. The animals were maintained in shade at an air temperature of 28 degrees C and relative humidity of 47%. Coat thickness was 1 to 2mm, so Ts closely represented skin temperature. Mean Ts of 5 x 20cm areas on the upper and lower hind and front legs, rump, chest, abdomen side, and neck were obtained by converting to temperature their respective gray intensity in single frames obtained at 10-s intervals. Little change occurred in Ts during the first wetting (0.1+/-0.6 degrees C), but it decreased rapidly thereafter (1.6+/-0.6 degrees C in the fifth wetting). The Ts also decreased, to a smaller extent, in areas that remained dry (0.7+/-1.0 degrees C). In all body sites, a plateau in Ts was reached by 2 min after wetting. The difference between dry and wet areas in the first cooling cycle was approximately 1.2 degrees C. The Ts of different body areas decreased during consecutive cooling cycles and reached a plateau by 3 cooling cycles in dry sites (front leg, neck, abdomen side), by 5 cooling cycles in the hind leg, and 7 cooling cycles in the rump and chest. The reduction in mean Ts produced by 7 cycles was 4.0 to 6.0 degrees C in wetted areas and 1.6 to 3.7 degrees C in sites that were not wetted. Initial rectal

Comparison of three different methods to prevent heat loss in healthy dogs undergoing 90 minutes of general anesthesia.

PubMed

Clark-Price, Stuart C; Dossin, Olivier; Jones, Katherine R; Otto, Angela N; Weng, Hsin-Yi

2013-05-01

To compare a towel under, a warm water pad under or a forced warm air blanket over dogs as techniques to reduce heat loss during a standardized anesthetic. Prospective, randomized, crossover study. Eight, healthy, mixed breed dogs weighing 16.3-19.6 kg. Dogs were anesthetized four times for 90 minutes. Dogs were placed on a steel table (treatment TA), with a cotton towel (treatment TO) or a circulating warm water pad (treatment WP) between the dog and the table, or with, a towel under the dog and covered with a forced warm air blanket (treatment WAB). Rectal temperature (RT) was recorded at 5 minute intervals. Changes in temperature (ΔRT) were calculated as the RT at a given point subtracted from the RT before anesthesia (baseline) and compared over time. After 90 minutes of anesthesia, the ΔRT was 3.42 °C ± 0.29 for TA, 2.78 °C ± 0.43 for TO, 1.98 °C ± 0.29 for WP, and 0.91 °C ± 0.27 for WAB. Significant differences in ΔRT occurred between TA and WAB at 20 minutes (0.94 °C ± 0.42, p = 0.0206), between TO and WAB at 30 minutes (1.16 °C ± 0.62, p = 0.0063), between WP and WAB at 50 minutes (0.96 °C ± 0.98, p = 0.0249), between TA and WP at 35 minutes (1.19 °C ± 0.54, p = 0.0091), between TO and WP at 70 minutes (1.12 °C ± 0.56, p = 0.0248), and between TA and TO at 75 minutes (0.96 °C ± 0.62, p = 0.0313). These differences in ΔRT between each treatment persisted from the times indicated until the end of the anesthesia. During anesthesia, forced warm air blankets were superior to other methods tested for limiting heat loss. An efficient heat loss technique should be used for anesthesia longer than 20 minutes duration in medium sized dogs. © 2013 The Authors. Veterinary Anaesthesia and Analgesia © 2013 Association of Veterinary Anaesthetists and the American College of Veterinary Anesthesia and Analgesia.

Fundamentals of heat measurement. [heat flux transducers

NASA Technical Reports Server (NTRS)

Gerashchenko, O. A.

1979-01-01

Various methods and devices for obtaining experimental data on heat flux density over wide ranges of temperature and pressure are examined. Laboratory tests and device fabrication details are supplemented by theoretical analyses of heat-conduction and thermoelectric effects, providing design guidelines and information relevant to further research and development. A theory defining the measure of correspondence between transducer signal and the measured heat flux is established for individual (isolated) heat flux transducers subject to space and time-dependent loading. An analysis of the properties of stacked (series-connected) transducers of various types (sandwich-type, plane, and spiral) is used to derive a similarity theory providing general governing relationships. The transducers examined are used in 36 types of derivative devices involving direct heat loss measurements, heat conduction studies, radiation pyrometry, calorimetry in medicine and industry and nuclear reactor dosimetry.

Alternating current losses in superconducting coils

NASA Technical Reports Server (NTRS)

Wipf, S. L.; Guderjahn, C. A.

1972-01-01

Report examines relationship between coil loss and frequency and heat loss in coil as a function of the magnetic field H. Information is of value to manufacturers of superconducting magnets, motors and generators.

Resistance of Legionella and Acanthamoeba mauritaniensis to heat treatment as determined by relative and quantitative polymerase chain reactions.

PubMed

Dobrowsky, Penelope H; Khan, Sehaam; Khan, Wesaal

2017-10-01

Legionella and Acanthamoeba spp. persist in harvested rainwater pasteurized at high temperatures (> 72°C) and the interaction mechanisms exhibited between these organisms need to be elucidated. The resistance of two Legionella reference strains (Legionella pneumophila ATCC 33152 and Legionella longbeachae ATCC 33462), three environmental strains [Legionella longbeachae (env.), Legionella norrlandica (env.) and Legionella rowbothamii (env.)] and Acanthamoeba mauritaniensis ATCC 50676 to heat treatment (50-90°C) was determined by monitoring culturability and viability [ethidium monoazide quantitative polymerase chain reaction (EMA-qPCR)]. The expression of metabolic and virulence genes of L. pneumophila ATCC 33152 (lolA, sidF, csrA) and L. longbeachae (env.) (lolA) in co-culture with A. mauritaniensis ATCC 50676 during heat treatment (50-90°C) was monitored using relative qPCR. While the culturability (CFU/mL) and viability (gene copies/mL) of the Legionella strains reduced significantly (p < 0.05) following heat treatment (60-90°C), L. longbeachae (env.) and L. pneumophila ATCC 33152 were culturable following heat treatment at 50-60°C. Metabolically active trophozoites and dormant cysts of A. mauritaniensis ATCC 50676 were detected at 50°C and 60-90°C, respectively. For L. pneumophila ATCC 33152, lolA expression remained constant, sidF expression increased and the expression of csrA decreased during co-culture with A. mauritaniensis ATCC 50676. For L. longbeachae (env.), while lolA was up-regulated at 50-70°C, expression was not detected at 80-90°C and in co-culture. In conclusion, while heat treatment may reduce the number of viable Legionella spp. in monoculture, results indicate that the presence of A. mauritaniensis increases the virulence of L. pneumophila during heat treatment. The virulence of Legionella spp. in co-culture with Acanthamoeba spp. should thus be monitored in water distribution systems where temperature (heat) is utilized for treatment

Diffusive loss of argon in response to melt vein formation in polygenetic impact melt breccias

NASA Astrophysics Data System (ADS)

Mercer, Cameron M.; Hodges, Kip V.

2017-08-01

Many planetary surfaces in the solar system have experienced prolonged bombardment. With each impact, new rocks can be assembled that incorporate freshly generated impact melts with fragments of older rocks. Some breccias can become polygenetic, containing multiple generations of impact melt products, and can potentially provide important insights into the extensive bombardment history of a region. However, the amount of chronological information that can be extracted from such samples depends on how well the mineral isotopic systems of geochronometers can preserve the ages of individual melt generations without being disturbed by younger events. We model the thermal evolution of impact melt veins and the resulting loss of Ar from K-bearing phases common in impact melt breccias to assess the potential for preserving the 40Ar/39Ar ages of individual melt generations. Our model results demonstrate that millimeter-scale, clast-free melt veins cause significant heating of adjacent host rock minerals and can cause detectable Ar loss in contact zones that are generally thinner than, and at most about the same thickness as, the vein width. The incorporation of cold clasts in melt veins reduces the magnitudes of heating and Ar loss in the host rocks, and Ar loss can be virtually undetectable for sufficiently clast-rich veins. Quantitative evidence of the timing of impacts, as measured with the 40Ar/39Ar method, can be preserved in polygenetic impact melt breccias, particularly for those containing millimeter-scale bodies of clast-bearing melt products.

Numerical Investigation of the Thermal Regime of Underground Channel Heat Pipelines Under Flooding Conditions with the Use of a Conductive-Convective Heat Transfer Model

NASA Astrophysics Data System (ADS)

Polovnikov, V. Yu.

2018-05-01

This paper presents the results of numerical analysis of thermal regimes and heat losses of underground channel heating systems under flooding conditions with the use of a convective-conductive heat transfer model with the example of the configuration of the heat pipeline widely used in the Russian Federation — a nonpassage ferroconcrete channel (crawlway) and pipelines insulated with mineral wool and a protective covering layer. It has been shown that convective motion of water in the channel cavity of the heat pipeline under flooding conditions has no marked effect on the intensification of heat losses. It has been established that for the case under consideration, heat losses of the heat pipeline under flooding conditions increase from 0.75 to 52.39% due to the sharp increase in the effective thermal characteristics of the covering layer and the heat insulator caused by their moistening.

Numerical Investigation of the Thermal Regime of Underground Channel Heat Pipelines Under Flooding Conditions with the Use of a Conductive-Convective Heat Transfer Model

NASA Astrophysics Data System (ADS)

Polovnikov, V. Yu.

2018-03-01

This paper presents the results of numerical analysis of thermal regimes and heat losses of underground channel heating systems under flooding conditions with the use of a convective-conductive heat transfer model with the example of the configuration of the heat pipeline widely used in the Russian Federation — a nonpassage ferroconcrete channel (crawlway) and pipelines insulated with mineral wool and a protective covering layer. It has been shown that convective motion of water in the channel cavity of the heat pipeline under flooding conditions has no marked effect on the intensification of heat losses. It has been established that for the case under consideration, heat losses of the heat pipeline under flooding conditions increase from 0.75 to 52.39% due to the sharp increase in the effective thermal characteristics of the covering layer and the heat insulator caused by their moistening.

Generation of a Parabolic Trough Collector Efficiency Curve from Separate Measurements of Outdoor Optical Efficiency and Indoor Receiver Heat Loss: Preprint

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kutscher, C.; Burkholder, F.; Stynes, K.

2010-10-01

The overall efficiency of a parabolic trough collector is a function of both the fraction of direct normal radiation absorbed by the receiver (the optical efficiency) and the heat lost to the environment when the receiver is at operating temperature. The overall efficiency can be determined by testing the collector under actual operating conditions or by separately measuring these two components. This paper describes how outdoor measurement of the optical efficiency is combined with laboratory measurements of receiver heat loss to obtain an overall efficiency curve. Further, it presents a new way to plot efficiency that is more robust overmore » a range of receiver operating temperatures.« less

Measurement of temperature-dependent specific heat of biological tissues.

PubMed

Haemmerich, Dieter; Schutt, David J; dos Santos, Icaro; Webster, John G; Mahvi, David M

2005-02-01

We measured specific heat directly by heating a sample uniformly between two electrodes by an electric generator. We minimized heat loss by styrofoam insulation. We measured temperature from multiple thermocouples at temperatures from 25 degrees C to 80 degrees C while heating the sample, and corrected for heat loss. We confirm method accuracy with a 2.5% agar-0.4% saline physical model and obtain specific heat of 4121+/-89 J (kg K)(-1), with an average error of 3.1%.

Estimation of heat loss from a cylindrical cavity receiver based on simultaneous energy and exergy analyses

NASA Astrophysics Data System (ADS)

Madadi, Vahid; Tavakoli, Touraj; Rahimi, Amir

2015-03-01

This study undertakes the experimental and theoretical investigation of heat losses from a cylindrical cavity receiver employed in a solar parabolic dish collector. Simultaneous energy and exergy equations are used for a thermal performance analysis of the system. The effects of wind speed and its direction on convection loss has also been investigated. The effects of operational parameters, such as heat transfer fluid mass flow rate and wind speed, and structural parameters, such as receiver geometry and inclination, are investigated. The portion of radiative heat loss is less than 10%. An empirical and simplified correlation for estimating the dimensionless convective heat transfer coefficient in terms of the Re mathrm {Re} number and the average receiver wall temperature is proposed. This correlation is applicable for a wind speed range of 0.10.1 to 10 m/s. Moreover, the proposed correlation for Nu mathrm {Nu} number is validated using experimental data obtained through the experiments carried out with a conical receiver with two aperture diameters. The coefficient of determination R2 and the normalized root

Magnetic heating of stellar chromospheres and coronae

NASA Astrophysics Data System (ADS)

van Ballegooijen, A. A.

The theoretical discussion of magnetic heating focuses on heating by dissipation of field-aligned electric currents. Several mechanisms are set forth to account for the very high current densities needed to generate the heat, but observed radiative losses do not justify the resultant Ohmic heating rate. Tearing modes, 'turbulent resistivity', and 'hyper-resistivity' are considered to resolve the implied inefficiency of coronal heating. Because the mechanisms are not readily applicable to the sun, transverse magnetic energy flows and magnetic flare release are considered to account for the magnitude of observed radiative loss. High-resolution observations of the sun are concluded to be an efficient way to examine the issues of magnetic heating in spite of the very small spatial scales of the heating processes.

Limited effectiveness of heat acclimation to soldiers wearing US Army and US Air Force chemical protective clothing. Technical report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chang, S.K.; Gonzalez, R.R.

1995-11-01

Heat acclilmation-induced sweating responses have the potential of reducing heat strain for soldiers wearing chemical protective garment. However, this potential benefit is strongly affected by the properties of the garment. If the clothing ensemble permits sufficient evaporative heat dissipation, then heat acclimation becomes helpful in reducing heat strain. On the other hand, if the garment creates an impenetrable barrier to moisture, no benefit can be gained from heat acclimation as the additional sweating cannot be evaporated. We studied 10 subjects exercising on a treadmill while wearing two different U.S. military chemical protective ensembles. Skin heat flux, skin temperature, core temperature,more » metabolic heat production, and heart rate were measured. We found that the benefit of heat acclimation is strongly dependent on an unimpeded ability of evaporative heat loss from skin areas. The evaporative potential (EP), a measure of thermal insulation modified by moisture permeability, of the clothing ensemble offers a quantitative index useful to determine whether heat acclimation is helpful while protective clothing system. Our data show that when EP is less than 15%, heat acclimation affords no benefit. An evaporative potential graph is created to aid in this determination.« less

Dissection of Heat Tolerance Mechanisms in Maize

USDA-ARS?s Scientific Manuscript database

Heat stress severely limits plant productivity and causes extensive economic loss to US agriculture. Understanding heat adaptation mechanisms in crop plants is crucial to the success of developing heat tolerant varieties. Heat waves (heat stress) often occur sporadically during the growing season o...

Spatially resolved quantitative mapping of thermomechanical properties and phase transition temperatures using scanning probe microscopy

DOEpatents

Jesse, Stephen; Kalinin, Sergei V; Nikiforov, Maxim P

2013-07-09

An approach for the thermomechanical characterization of phase transitions in polymeric materials (polyethyleneterephthalate) by band excitation acoustic force microscopy is developed. This methodology allows the independent measurement of resonance frequency, Q factor, and oscillation amplitude of a tip-surface contact area as a function of tip temperature, from which the thermal evolution of tip-surface spring constant and mechanical dissipation can be extracted. A heating protocol maintained a constant tip-surface contact area and constant contact force, thereby allowing for reproducible measurements and quantitative extraction of material properties including temperature dependence of indentation-based elastic and loss moduli.

Micro-Scale Regenerative Heat Exchanger

NASA Technical Reports Server (NTRS)

Moran, Matthew E.; Stelter, Stephan; Stelter, Manfred

2004-01-01

A micro-scale regenerative heat exchanger has been designed, optimized and fabricated for use in a micro-Stirling device. Novel design and fabrication techniques enabled the minimization of axial heat conduction losses and pressure drop, while maximizing thermal regenerative performance. The fabricated prototype is comprised of ten separate assembled layers of alternating metal-dielectric composite. Each layer is offset to minimize conduction losses and maximize heat transfer by boundary layer disruption. A grating pattern of 100 micron square non-contiguous flow passages were formed with a nominal 20 micron wall thickness, and an overall assembled ten-layer thickness of 900 microns. Application of the micro heat exchanger is envisioned in the areas of micro-refrigerators/coolers, micropower devices, and micro-fluidic devices.

Development of three stable isotope dilution assays for the quantitation of (E)-2-butenal (crotonaldehyde) in heat-processed edible fats and oils as well as in food.

PubMed

Granvogl, Michael

2014-02-12

Three stable isotope dilution assays (SIDAs) were developed for the quantitation of (E)-2-butenal (crotonaldehyde) in heat-processed edible fats and oils as well as in food using synthesized [¹³C₄]-crotonaldehyde as internal standard. First, a direct headspace GC-MS method, followed by two indirect methods on the basis of derivatization with either pentafluorophenylhydrazine (GC-MS) or 2,4-dinitrophenylhydrazine (LC-MS/MS), was developed. All methods are also suitable for the quantitation of acrolein using the standard [¹³C₃]-acrolein. Applying these three methods on five different types of fats and oils varying in their fatty acid compositions revealed significantly varying crotonaldehyde concentrations for the different samples, but nearly identical quantitative data for all methods. Formed amounts of crotonaldehyde were dependent not only on the type of oil, e.g., 0.29-0.32 mg/kg of coconut oil or 33.9-34.4 mg/kg of linseed oil after heat-processing for 24 h at 180 °C, but also on the applied temperature and time. The results indicated that the concentration of formed crotonaldehyde seemed to be correlated with the amount of linolenic acid in the oils. Furthermore, the formation of crotonaldehyde was compared to that of its homologue acrolein, demonstrating that acrolein was always present in higher amounts in heat-processed oils, e.g., 12.3 mg of crotonaldehyde/kg of rapeseed oil in comparison to 23.4 mg of acrolein/kg after 24 h at 180 °C. Finally, crotonaldehyde was also quantitated in fried food, revealing concentrations from 12 to 25 μg/kg for potato chips and from 8 to 19 μg/kg for donuts, depending on the oil used.

Analysis of Thermal Losses for a Variety of Single-Junction Photovoltaic Cells: An Interesting Means of Thermoelectric Heat Recovery

NASA Astrophysics Data System (ADS)

Lorenzi, Bruno; Acciarri, Maurizio; Narducci, Dario

2015-06-01

Exploitation of solar energy conversion has become a fundamental aspect of satisfying a growing demand for energy. Thus, improvement of the efficiency of conversion in photovoltaic (PV) devices is highly desirable to further promote this source. Because it is well known that the most relevant efficiency constraint, especially for single-junction solar cells, is unused heat within the device, hybrid thermo-photovoltaic systems seem promising . Among several hybrid solutions proposed in the literature, coupling of thermoelectric and PV devices seems one of the most interesting. Taking full advantage of this technology requires proper definition and analysis of the thermal losses occurring in PV cells. In this communication we propose a novel analysis of such losses, decoupling source-dependent and absorber-dependent losses. This analysis enables an evaluation of the actual recoverable amount of energy, depending on the absorber used in the PV cell. It shows that for incoming solar irradiation of , and depending on the choice of material, the maximum available thermal power ranges from (for single-crystal silicon) to (for amorphous silicon).

Cycles in metabolism and heat loss

NASA Technical Reports Server (NTRS)

Annis, J. F.; Troutman, S. J.; Webb, P.

1974-01-01

Using calorimetric techniques, subjects' metabolism, thermoregulation, and body temperatures were monitored continuously for 24-hour days, using three types of experimental routines. A water cooling garment (WCG) was used for direct calorimetry, while partitional calorimetry was used to establish a non-suited comparison for one of the routines. In this replicated routine, called the quiet day, the subjects were sedentary throughout the daytime hours and slept normally at night. Results indicate that the WCG may act to reduce 24-hour total oxygen consumption (VO2) or heat production, possibly due to the lowered energy cost of thermoregulation.

Evidence for increased latent heat transport during the Cretaceous (Albian) greenhouse warming

USGS Publications Warehouse

Ufnar, David F.; Gonzalez, Luis A.; Ludvigson, Greg A.; Brenner, Richard L.; Witzke, B.J.

2004-01-01

Quantitative estimates of increased heat transfer by atmospheric H 2O vapor during the Albian greenhouse warming suggest that the intensified hydrologic cycle played a greater role in warming high latitudes than at present and thus represents a viable alternative to oceanic heat transport. Sphaerosiderite ??18O values in paleosols of the North American Cretaceous Western Interior Basin are a proxy for meteoric ??18O values, and mass-balance modeling results suggest that Albian precipitation rates exceeded modern rates at both mid and high latitudes. Comparison of modeled Albian and modern precipitation minus evaporation values suggests amplification of the Albian moisture deficit in the tropics and moisture surplus in the mid to high latitudes. The tropical moisture deficit represents an average heat loss of ???75 W/m2 at 10??N paleolatitude (at present, 21 W/m2). The increased precipitation at higher latitudes implies an average heat gain of ???83 W/m2 at 45??N (at present, 23 W/m2) and of 19 W/m2 at 75??N (at present, 4 W/m2). These estimates of increased poleward heat transfer by H2O vapor during the Albian may help to explain the reduced equator-to-pole temperature gradients. ?? 2004 Geological Society of America.

A Spectroscopic Study of Impurity Behavior in Neutral-beam and Ohmically Heated TFTR Discharges

DOE R&D Accomplishments Database

Stratton, B. C.; Ramsey, A. T.; Boody, F. P.; Bush, C. E.; Fonck, R. J.; Groenbner, R. J.; Hulse, R. A.; Richards, R. K.; Schivell, J.

1987-02-01

Quantitative spectroscopic measurements of Z{sub eff}, impurity densities, and radiated power losses have been made for ohmic- and neutral-beam-heated TFTR discharges at a plasma current of 2.2 MA and toroidal field of 4.7 T. Variations in these quantities with line-average plasma density (anti n{sub e}) and beam power up to 5.6 MW are presented for discharges on a graphite movable limiter. A detailed discussion of the use of an impurity transport model to infer absolute impurity densities and radiative losses from line intensity and visible continuum measurements is given. These discharges were dominated by low-Z impurities with carbon having a considerably higher density than oxygen, except in high-anti n{sub e} ohmic discharges, where the densities of carbon and oxygen were comparable. Metallic impurity concentrations and radiative losses were small, resulting in hollow radiated power profiles and fractions of the input power radiated being 30 to 50% for ohmic heating and 30% or less with beam heating. Spectroscopic estimates of the radiated power were in good agreement with bolometrically measured values. Due to an increase in the carbon density, Z{sub eff} rose from 2.0 to 2.8 as the beam power increased from 0 to 5.6 MW, pointing to a potentially serious dilution of the neutron-producing plasma ions as the beam power increased. Both the low-Z and metallic impurity concentrations were approximately constant with minor radius, indicating no central impurity accumulation in these discharges.

Infrared thermography with non-uniform heat flux boundary conditions on the rotor endwall of an axial turbine

NASA Astrophysics Data System (ADS)

Lazzi Gazzini, S.; Schädler, R.; Kalfas, A. I.; Abhari, R. S.

2017-02-01

It is technically challenging to measure heat fluxes on the rotating components of gas turbines, yet accurate knowledge of local heat loads under engine-representative conditions is crucial for ensuring the reliability of the designs. In this work, quantitative image processing tools were developed to perform fast and accurate infrared thermography measurements on 3D-shaped film-heaters directly deposited on the turbine endwalls. The newly developed image processing method and instrumentation were used to measure the heat load on the rotor endwalls of an axial turbine. A step-transient heat flux calibration technique is applied to measure the heat flux generated locally by the film heater, thus eliminating the need for a rigorously iso-energetic boundary condition. On-board electronics installed on the rotor record the temperature readings of RTDs installed in the substrate below the heaters in order to evaluate the conductive losses in the solid. Full maps of heat transfer coefficient and adiabatic wall temperature are produced for two different operating conditions, demonstrating the sensitivity of the technique to local flow features and variations in heat transfer due to Reynolds number effect.

Heat Management in Thermoelectric Power Generators

PubMed Central

Zebarjadi, M.

2016-01-01

Thermoelectric power generators are used to convert heat into electricity. Like any other heat engine, the performance of a thermoelectric generator increases as the temperature difference on the sides increases. It is generally assumed that as more heat is forced through the thermoelectric legs, their performance increases. Therefore, insulations are typically used to minimize the heat losses and to confine the heat transport through the thermoelectric legs. In this paper we show that to some extend it is beneficial to purposely open heat loss channels in order to establish a larger temperature gradient and therefore to increase the overall efficiency and achieve larger electric power output. We define a modified Biot number (Bi) as an indicator of requirements for sidewall insulation. We show cooling from sidewalls increases the efficiency for Bi values less than one, and decreases the efficiency for Bi values larger than one. PMID:27033717

Efficiencies and coefficients of performance of heat engines, refrigerators, and heat pumps with friction: a universal limiting behavior.

PubMed

Bizarro, João P S; Rodrigues, Paulo

2012-11-01

For work-producing heat engines, or work-consuming refrigerators and heat pumps, the percentage decrease caused by friction in their efficiencies, or coefficients of performance (COP's), is approximately given by the ratio W(fric)/W between the work spent against friction forces and the work performed by, or delivered to, the working fluid. This universal scaling, which applies in the limit of small friction (W(fric)/W heat-engine efficiencies), allows a simple and quick estimate of the impact that friction losses can have on the FOM's of thermal engines and plants, or of the level of those losses from the observed and predicted FOM's. In the case of refrigerators and heat pumps, if W(fric)/W heat engines), the COP percentage decrease due to friction approaches asymptotically (W(fric)/W)/(1+W(fric)/W) instead of W(fric)/W. Estimates for the level of frictional losses using the Carnot (or, for heat engines and power plants only, the Curzon-Ahlborn) predictions and observed FOM's of real power plants, heat engines, refrigerators, and heat pumps show that they usually operate in domains where these behaviors are valid.

On sweat analysis for quantitative estimation of dehydration during physical exercise.

PubMed

Ring, Matthias; Lohmueller, Clemens; Rauh, Manfred; Eskofier, Bjoern M

2015-08-01

Quantitative estimation of water loss during physical exercise is of importance because dehydration can impair both muscular strength and aerobic endurance. A physiological indicator for deficit of total body water (TBW) might be the concentration of electrolytes in sweat. It has been shown that concentrations differ after physical exercise depending on whether water loss was replaced by fluid intake or not. However, to the best of our knowledge, this fact has not been examined for its potential to quantitatively estimate TBW loss. Therefore, we conducted a study in which sweat samples were collected continuously during two hours of physical exercise without fluid intake. A statistical analysis of these sweat samples revealed significant correlations between chloride concentration in sweat and TBW loss (r = 0.41, p <; 0.01), and between sweat osmolality and TBW loss (r = 0.43, p <; 0.01). A quantitative estimation of TBW loss resulted in a mean absolute error of 0.49 l per estimation. Although the precision has to be improved for practical applications, the present results suggest that TBW loss estimation could be realizable using sweat samples.

Heat Pipe Materials Compatibility

NASA Technical Reports Server (NTRS)

Eninger, J. E.; Fleischman, G. L.; Luedke, E. E.

1976-01-01

An experimental program to evaluate noncondensable gas generation in ammonia heat pipes was completed. A total of 37 heat pipes made of aluminum, stainless steel and combinations of these materials were processed by various techniques, operated at different temperatures and tested at low temperature to quantitatively determine gas generation rates. In order of increasing stability are aluminum/stainless combination, all aluminum and all stainless heat pipes. One interesting result is the identification of intentionally introduced water in the ammonia during a reflux step as a means of surface passivation to reduce gas generation in stainless-steel/aluminum heat pipes.

Quantitative investigation into the source of current slump in AlGaN/GaN HEMT on both Si (111) and sapphire: Self-heating and trapping

NASA Astrophysics Data System (ADS)

Bag, Ankush; Mukhopadhyay, Partha; Ghosh, Saptarsi; Das, Palash; Chakraborty, Apurba; Dinara, Syed M.; Kabi, Sanjib; Biswas, Dhurbes

2015-05-01

We have experimentally studied trapping and self-heating effect in terms of current slump in AlGaN/GaN HEMT grown and identically processed on Silicon (111) and Sapphire (0001) substrates. Different responses have been observed through DC characterization of different duty cycle (100%, 50%, 5% and 0.5%) of pulses at drain end. Effect of self-heating is more in case of HEMT on Sapphire due to its comparative poor thermal conductivity whereas trapped charges have strong contribution in current drop of HEMT on Si (111) due to larger lattice as well as thermal expansion coefficient mismatched epitaxy between GaN and Si (111). These results have been compared among substrates that lead us to find out optimal source of current slump quantitatively between traps and self-heating.

Heat loss regulation: role of appendages and torso in the deer mouse and the white rabbit.

PubMed

Conley, K E; Porter, W P

1985-01-01

Thermal conductance was subdivided into the component conductances of the appendages and torso using a heat transfer analysis for the deer mouse, Peromyscus maniculatus, and the white rabbit, Oryctolagus cuniculus. Our analysis was based on laboratory measurements of skin temperature and respiratory gas exchange made between air temperatures of 8 and 34 degrees C for the deer mouse, and from published data for the white rabbit. Two series conductances to heat transfer for each appendage and torso were evaluated: internal (hin), for blood flow and tissue conduction to the skin surface, and external (hex), for heat loss from the skin surface to the environment. These two series conductances were represented in a single, total conductance (htot). The limit to htot was set by hex and was reached by the torso htot of both animals. The increase in torso htot observed with air temperature for the mouse suggests that a pilomotor change in fur depth occurred. A control of htot below the limit set by hex was achieved by the hin of each appendage. Elevation of mouse thermal conductance (C) resulted from increases in feet, tail, and torso htot. In contrast, the rabbit showed no change in torso htot between 5 and 30 degrees C and ear htot exclusively increased C over these air temperatures. We suggest that the hyperthermia reported for the rabbit at 35 degrees C resulted from C reaching the physical limit set by torso and near hex. Thus the ear alone adjusted rabbit C, whereas the feet, tail, and the torso contributed to the adjustment of mouse C.

Influence of sire and sire breed (Gyr versus Holstein) on establishment of pregnancy and embryonic loss in lactating Holstein cows during summer heat stress.

PubMed

Pegorer, Marcelo F; Vasconcelos, José L M; Trinca, Luzia A; Hansen, Peter J; Barros, Ciro M

2007-03-01

Heat stress has negative effects on pregnancy rates of lactating dairy cattle. There are genetic differences in tolerance to heat stress; Bos taurus indicus (B. t. indicus) cattle and embryos are more thermotolerant than Bos taurus taurus (B. t. taurus). In the present study, the effects of sire and sire breed on conception and embryonic/fetal loss rates of lactating Holstein cows during the Brazilian summer were determined. In Experiment 1, cows (n=302) were AI after estrus detection or at a fixed-time with semen from one Gyr (B. t. indicus) or one Holstein sire (B. t. taurus). Pregnancy was diagnosed 80 days after AI. In Experiment 2, cows (n=811) were AI with semen from three Gyr and two Holstein sires. Pregnancy was diagnosed at 30-40 and at 60-80 days after AI. Cows diagnosed pregnant at the first examination but non-pregnant at the second were considered as having lost their embryo or fetus. Data were analyzed by logistic regression. The model considered the effect of sire within breed, sire breed, days postpartum, period of lactation, and AI type (AI after estrus versus fixed-time). There was no effect of the AI type, days postpartum or milk production on conception or embryonic loss rates. The use of Gyr bulls increased pregnancy rate when compared to Holstein bulls [9.1% (60/657) versus 5.0% (23/456), respectively, P=0.008; data from Experiments 1 and 2 combined]. Additionally, in Experiment 2, cows inseminated using semen from sire #4 (Gyr) had lower embryonic loss (10%) when compared with other B. t. indicus (35.3% and 40%) or B. t. taurus sires (18.2% and 38.5%, P=0.03). In conclusion, the use of B. t. indicus sires may result in higher conception rates in lactating Holstein cows during summer heat stress. Moreover, sire can affect embryonic loss and selection of bulls according to this criterion may result in higher parturition rates in lactating Holstein cows.

Absorption heat pump system

DOEpatents

Grossman, Gershon; Perez-Blanco, Horacio

1984-01-01

An improvement in an absorption heat pump cycle is obtained by adding adiabatic absorption and desorption steps to the absorber and desorber of the system. The adiabatic processes make it possible to obtain the highest temperature in the absorber before any heat is removed from it and the lowest temperature in the desorber before heat is added to it, allowing for efficient utilization of the thermodynamic availability of the heat supply stream. The improved system can operate with a larger difference between high and low working fluid concentrations, less circulation losses, and more efficient heat exchange than a conventional system.

Absorption-heat-pump system

DOEpatents

Grossman, G.; Perez-Blanco, H.

1983-06-16

An improvement in an absorption heat pump cycle is obtained by adding adiabatic absorption and desorption steps to the absorber and desorber of the system. The adiabatic processes make it possible to obtain the highest temperature in the absorber before any heat is removed from it and the lowest temperature in the desorber before heat is added to it, allowing for efficient utilization of the thermodynamic availability of the heat supply stream. The improved system can operate with a larger difference between high and low working fluid concentrations, less circulation losses, and more efficient heat exchange than a conventional system.

24 CFR 3280.507 - Comfort heat gain.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 24 Housing and Urban Development 5 2011-04-01 2011-04-01 false Comfort heat gain. 3280.507 Section... DEVELOPMENT MANUFACTURED HOME CONSTRUCTION AND SAFETY STANDARDS Thermal Protection § 3280.507 Comfort heat... part. (a) Transmission heat gains. Homes complying with this section shall meet the minimum heat loss...

24 CFR 3280.507 - Comfort heat gain.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 24 Housing and Urban Development 5 2014-04-01 2014-04-01 false Comfort heat gain. 3280.507 Section... DEVELOPMENT MANUFACTURED HOME CONSTRUCTION AND SAFETY STANDARDS Thermal Protection § 3280.507 Comfort heat... part. (a) Transmission heat gains. Homes complying with this section shall meet the minimum heat loss...

24 CFR 3280.507 - Comfort heat gain.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 24 Housing and Urban Development 5 2012-04-01 2012-04-01 false Comfort heat gain. 3280.507 Section... DEVELOPMENT MANUFACTURED HOME CONSTRUCTION AND SAFETY STANDARDS Thermal Protection § 3280.507 Comfort heat... part. (a) Transmission heat gains. Homes complying with this section shall meet the minimum heat loss...

24 CFR 3280.507 - Comfort heat gain.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 24 Housing and Urban Development 5 2013-04-01 2013-04-01 false Comfort heat gain. 3280.507 Section... DEVELOPMENT MANUFACTURED HOME CONSTRUCTION AND SAFETY STANDARDS Thermal Protection § 3280.507 Comfort heat... part. (a) Transmission heat gains. Homes complying with this section shall meet the minimum heat loss...

The impact of heat waves on surface urban heat island and local economy in Cluj-Napoca city, Romania

NASA Astrophysics Data System (ADS)

Herbel, Ioana; Croitoru, Adina-Eliza; Rus, Adina Viorica; Roşca, Cristina Florina; Harpa, Gabriela Victoria; Ciupertea, Antoniu-Flavius; Rus, Ionuţ

2017-07-01

The association between heat waves and the urban heat island effect can increase the impact on environment and society inducing biophysical hazards. Heat stress and their associated public health problems are among the most frequent. This paper explores the heat waves impact on surface urban heat island and on the local economy loss during three heat periods in Cluj-Napoca city in the summer of 2015. The heat wave events were identified based on daily maximum temperature, and they were divided into three classes considering the intensity threshold: moderate heat waves (daily maximum temperature exceeding the 90th percentile), severe heat waves (daily maximum temperature over the 95th percentile), and extremely severe heat waves (daily maximum temperature exceeding the 98th percentile). The minimum length of an event was of minimum three consecutive days. The surface urban heat island was detected based on land surface temperature derived from Landsat 8 thermal infrared data, while the economic impact was estimated based on data on work force structure and work productivity in Cluj-Napoca derived from the data released by Eurostat, National Bank of Romania, and National Institute of Statistics. The results indicate that the intensity and spatial extension of surface urban heat island could be governed by the magnitude of the heat wave event, but due to the low number of satellite images available, we should consider this information only as preliminary results. Thermal infrared remote sensing has proven to be a very efficient method to study surface urban heat island, due to the fact that the synoptic conditions associated with heat wave events usually favor cloud free image. The resolution of the OLI_TIRS sensor provided good results for a mid-extension city, but the low revisiting time is still a drawback. The potential economic loss was calculated for the working days during heat waves and the estimated loss reached more than 2.5 mil. EUR for each heat wave day

Basic Comfort Heating Principles.

ERIC Educational Resources Information Center

Dempster, Chalmer T.

The material in this beginning book for vocational students presents fundamental principles needed to understand the heating aspect of the sheet metal trade and supplies practical experience to the student so that he may become familiar with the process of determining heat loss for average structures. Six areas covered are: (1) Background…

Integration of Decentralized Thermal Storages Within District Heating (DH) Networks

NASA Astrophysics Data System (ADS)

Schuchardt, Georg K.

2016-12-01

Thermal Storages and Thermal Accumulators are an important component within District Heating (DH) systems, adding flexibility and offering additional business opportunities for these systems. Furthermore, these components have a major impact on the energy and exergy efficiency as well as the heat losses of the heat distribution system. Especially the integration of Thermal Storages within ill-conditioned parts of the overall DH system enhances the efficiency of the heat distribution. Regarding an illustrative and simplified example for a DH system, the interactions of different heat storage concepts (centralized and decentralized) and the heat losses, energy and exergy efficiencies will be examined by considering the thermal state of the heat distribution network.

Study of heat dissipation process from heat sink using lensless Fourier transform digital holographic interferometry.

PubMed

Kumar, Varun; Shakher, Chandra

2015-02-20

This paper presents the results of experimental investigations about the heat dissipation process of plate fin heat sink using digital holographic interferometry. Visual inspection of reconstructed phase difference maps of the air field around the heat sink with and without electric power in the load resistor provides qualitative information about the variation of temperature and the heat dissipation process. Quantitative information about the temperature distribution is obtained from the relationship between the digitally reconstructed phase difference map of ambient air and heated air. Experimental results are presented for different current and voltage in the load resistor to investigate the heat dissipation process. The effect of fin spacing on the heat dissipation performance of the heat sink is also investigated in the case of natural heat convection. From experimental data, heat transfer parameters, such as local heat flux and convective heat transfer coefficients, are also calculated.

Quantitative proteomics analysis by iTRAQ revealed underlying changes in thermotolerance of Arthrospira platensis.

PubMed

Chang, Rong; Lv, Bingxin; Li, Bosheng

2017-08-08

Growth temperature is a critical factor that affects cultivation of Arthrospira platensis which is a type of cyanobacterium widely known as Spirulina that has significant commercial value. To investigate the molecular mechanism underlying the thermotolerance of Spirulina, differential protein expression profiling was carried out using iTRAQ-based quantitative proteomic analysis. This study only analyzed changes in thylakoids. Among the 2085 proteins quantified, 43 differentially expressed proteins were selected based on the fold change cutoff scores of ≥2 or ≤0.5 for up-regulation or down-regulation, respectively. An analysis of these 43 proteins found that 23% of them are photosynthetic system proteins which include photosynthetic enzymes and pigment proteins. The dynamic change of these proteins indicates that photosynthetic system functions were profoundly affected under heat stress and the light-dependent reactions were probably the most sensitive to temperature changes. Meanwhile, to cope with the low energy production due to impaired photosynthesis there was a considerable down-shift in protein synthesis which is a very energy demanding process. The impaired photosynthesis led to low energy generation that was compensated by a down-shift in translation (the most energy-demanding process) and an up-shift of glycolysis. The reduction of many ribosome proteins may lead to a loss in translation efficiency; therefore, Spirulina may adopted a different mechanism to increase translational elongation under heat stress to compensate for this loss, such as elevate L7/L12 proteins. Changes were also found in the classical heat shock proteins, the ROS scavenging system, DNA-binding proteins, and some membrane proteins. In conclusion, this research demonstrate that heat stress induces profound changes in cellular physiology and shed light on the mechanism of the heat stress response and thermotolerance of Arthrospira platensis. Arthrospira platensis, widely known as

Shifts of heat availability and stressful temperatures in Russian Federation result in gains and losses of wheat thermal suitability

NASA Astrophysics Data System (ADS)

Di Paola, Arianna; Caporaso, Luca; Santini, Monia; Di Paola, Francesco; Vasenev, Ivan; Valentini, Riccardo

2017-04-01

Climate changes are likely to shift the suitability of lands devoted to cropping systems. We explored the past-to-future thermal suitability of Russian Federation for wheat (Triticum aestivum) culture through an ensemble of bias corrected CMIP5-GCMs outputs considering two representative concentration pathways (RCP 4.5 and 8.5). Thermal suitability assesses where wheat heat requirement, counted from suggested sowing dates, is satisfied without the occurrence of stressful hot and frost temperatures. Thermal requirement was estimated by means of phenological observations on soft wheat involving different wheat cultivar collected in different regions of Russian Federation, Azerbaidhan, Kazakhstan and Tadzhikistan, whilst stressful temperatures were taken from a literature survey. Results showed projected geographical shift of heat resource toward the north-eastern regions, currently mainly covered by forests and croplands, but also an increase of very hot temperatures in the most productive areas of the southern regions. Gains and losses were then quantified and discussed from both agronomical and climatic perspective.

At What Level of Heat Load Are Age-Related Impairments in the Ability to Dissipate Heat Evident in Females?

PubMed Central

Stapleton, Jill M.; Poirier, Martin P.; Flouris, Andreas D.; Boulay, Pierre; Sigal, Ronald J.; Malcolm, Janine; Kenny, Glen P.

2015-01-01

Studies have reported that older females have impaired heat loss responses during work in the heat compared to young females. However, it remains unclear at what level of heat stress these differences occur. Therefore, we examined whole-body heat loss [evaporative (HE) and dry heat loss, via direct calorimetry] and changes in body heat storage (∆Hb, via direct and indirect calorimetry) in 10 young (23±4 years) and 10 older (58±5 years) females matched for body surface area and aerobic fitness (VO2peak) during three 30-min exercise bouts performed at incremental rates of metabolic heat production of 250 (Ex1), 325 (Ex2) and 400 (Ex3) W in the heat (40°C, 15% relative humidity). Exercise bouts were separated by 15 min of recovery. Since dry heat gain was similar between young and older females during exercise (p=0.52) and recovery (p=0.42), differences in whole-body heat loss were solely due to HE. Our results show that older females had a significantly lower HE at the end of Ex2 (young: 383±34 W; older: 343±39 W, p=0.04) and Ex3 (young: 437±36 W; older: 389±29 W, p=0.008), however no difference was measured at the end of Ex1 (p=0.24). Also, the magnitude of difference in the maximal level of HE achieved between the young and older females became greater with increasing heat loads (Ex1=10.2%, Ex2=11.6% and Ex3=12.4%). Furthermore, a significantly greater ∆Hb was measured for all heat loads for the older females (Ex1: 178±44 kJ; Ex2: 151±38 kJ; Ex3: 216±25 kJ, p=0.002) relative to the younger females (Ex1: 127±35 kJ; Ex2: 96±45 kJ; Ex3: 146±46 kJ). In contrast, no differences in HE or ∆Hb were observed during recovery (p>0.05). We show that older habitually active females have an impaired capacity to dissipate heat compared to young females during exercise-induced heat loads of ≥325 W when performed in the heat. PMID:25790024

TiO2/water Nanofluid Heat Transfer in Heat Exchanger Equipped with Double Twisted-Tape Inserts

NASA Astrophysics Data System (ADS)

Eiamsa-ard, S.; Ketrain, R.; Chuwattanakul, V.

2018-05-01

Nowadays, heat transfer enhancement plays an important role in improving efficiency of heat transfer and thermal systems for numerous areas such as heat recovery processes, chemical reactors, air-conditioning/refrigeration system, food engineering, solar air/water heater, cooling of high power electronics etc. The present work presents the experimental results of the heat transfer enhancement of TiO2/water nanofluid in a heat exchanger tube fitted with double twisted tapes. The study covered twist ratios of twisted tapes (y/w) of 1.5, 2.0, and 2.5) while the concentration of the nanofluid was kept constant at 0.05% by volume. Observations show that heat transfer, friction loss and thermal performance increase as twist ratio (y/w) decreases. The use of the nanofluid in the tube equipped with the double twisted-tapes with the smallest twist ratio (y/w = 1.5) results in the increases of heat transfer rates and friction factor up to 224.8% and 8.98 times, respectively as compared to those of water. In addition, the experimental results performed that double twisted tapes induced dual swirling-flows which played an important role in improving fluid mixing and heat transfer enhancement. It is also observed that the TiO2/water nanofluid was responsible for low pressure loss behaviors.

24 CFR 3280.707 - Heat producing appliances.

Code of Federal Regulations, 2011 CFR

2011-04-01

... URBAN DEVELOPMENT MANUFACTURED HOME CONSTRUCTION AND SAFETY STANDARDS Heating, Cooling and Fuel Burning... oil burning comfort heating appliances shall have a flue loss of not more than 25 percent, and a...) Fuel-burning heat-producing appliances and refrigeration appliances, except ranges and ovens, shall be...

Enhanced heat transfer and frictional losses in heat exchanger tube with modified helical coiled inserts

NASA Astrophysics Data System (ADS)

Verma, Aditya; Kumar, Manoj; Patil, Anil Kumar

2018-04-01

The application of compact heat exchangers in any thermal system improves overall performance with a considerable reduction in size and weight. Inserts of different geometrical features have been used as turbulence promoting devices to increase the heat transfer rates. The present study deals with the experimental investigation of heat transfer and fluid flow characteristics of a tubular heat exchanger fitted with modified helical coiled inserts. Experiments have been carried out for a smooth tube without insert, tube fitted with helical coiled inserts, and modified helical coiled inserts. The helical coiled inserts are tested by varying the pitch ratio and wire diameter ratio from 0.5-1.5, and 0.063-0.125, respectively for the Reynolds number range of 1400 to 11,000. Experimental data have also been collected for the modified helical coiled inserts with gradually increasing pitch (GIP) and gradually decreasing pitch (GDP) configurations. The Nusselt number and friction factor values for helical coiled inserts are enhanced in the range of 1.42-2.62, 3.4-27.4, relative to smooth tube, respectively. The modified helical coiled insert showed enhancements in Nusselt number and friction factor values in the range of 1.49-3.14, 11.2-19.9, relative to smooth tube, respectively. The helical coiled and modified helical coiled inserts have thermo-hydraulic performance factor in the range of 0.59-1.29, 0.6-1.39, respectively. The empirical correlations of Nusselt number and friction factor for helical coiled inserts are proposed.

Physical explosion analysis in heat exchanger network design

NASA Astrophysics Data System (ADS)

Pasha, M.; Zaini, D.; Shariff, A. M.

2016-06-01

The failure of shell and tube heat exchangers is being extensively experienced by the chemical process industries. This failure can create a loss of production for long time duration. Moreover, loss of containment through heat exchanger could potentially lead to a credible event such as fire, explosion and toxic release. There is a need to analyse the possible worst case effect originated from the loss of containment of the heat exchanger at the early design stage. Physical explosion analysis during the heat exchanger network design is presented in this work. Baker and Prugh explosion models are deployed for assessing the explosion effect. Microsoft Excel integrated with process design simulator through object linking and embedded (OLE) automation for this analysis. Aspen HYSYS V (8.0) used as a simulation platform in this work. A typical heat exchanger network of steam reforming and shift conversion process was presented as a case study. It is investigated from this analysis that overpressure generated from the physical explosion of each heat exchanger can be estimated in a more precise manner by using Prugh model. The present work could potentially assist the design engineer to identify the critical heat exchanger in the network at the preliminary design stage.

Quantitative trait locus on chromosome 1q influences bone loss in young Mexican American adults

PubMed Central

Shaffer, John R.; Kammerer, Candace M.; Bruder, Jan M.; Cole, Shelley A.; Dyer, Thomas D.; Almasy, Laura; MacCluer, Jean W.; Blangero, John; Bauer, Richard L.; Mitchell, Braxton D.

2009-01-01

Introduction Bone loss occurs as early as the third decade and its cumulative effect throughout adulthood may impact risk for osteoporosis in later life, however the genes and environmental factors influencing early bone loss are largely unknown. We investigated the role of genes in the change in bone mineral density (BMD) in participants of the San Antonio Family Osteoporosis Study. Materials and Methods BMD change in 327 Mexican Americans (ages 25–45 years) from 32 extended pedigrees was calculated from DXA measurements at baseline and follow-up (3.5 to 8.9 years later). Family-based likelihood methods were used to estimate heritability (h2) and perform autosome-wide linkage analysis for BMD change of the proximal femur and forearm, and estimate heritability for BMD change of lumbar spine. Results BMD change was significantly heritable for total hip, ultradistal radius and 33% radius (h2 = 0.34, 0.34, 0.27, respectively, p < 0.03 for all), modestly heritable for femoral neck (h2 = 0.22, p = 0.06) and not heritable for spine BMD. Covariates associated with BMD change included age, sex, baseline BMD, menopause, body mass index, and interim BMI change, and accounted for 6% to 24% of phenotype variation. A significant quantitative trait locus (LOD = 3.6) for femoral neck BMD change was observed on chromosome 1q23. Conclusions We observed that change in BMD in young adults is heritable, and performed one of the first linkage studies for BMD change. Linkage to chromosome 1q23 suggests this region may harbor one or more genes involved in regulating early BMD change of the femoral neck. PMID:19067020

Computation of losses in a scramjet combustor

NASA Technical Reports Server (NTRS)

Kamath, Pradeep S.; Mcclinton, Charles R.

1992-01-01

The losses in a conceptual scramjet combustor at flight Mach numbers of 8, 10, 12, 16 and 20 are computed. These losses are extracted from three-dimensional parabolized Navier-Stokes solutions of the turbulent, reacting combustor flow field. A combustor performance index was defined based on the rationale that an efficient scramjet combustor should add heat to the fluid in such a manner as to maximize the stream thrust at the combustor exit while minimizing the losses. This index showed a decrease of more than 40 percent as the flight Mach number increased from 8 to 20, indicative of a drop in the thrust-producing potential of the scramjet at the upper end of the speed regime studied. A breakdown of the losses showed that dissipation, nonequilibrium chemistry and heat diffusion contributed roughly 15 percent, 35 percent, and 50 percent to the irreversible increase in entropy at Mach 8 and 22 percent, 13 and 65 percent at Mach 20.

Quantitative Infrared Image Analysis Of Simultaneous Upstream and Downstream Microgravity Flame Spread over Thermally-Thin Cellulose in Low Speed Forced Flow

NASA Technical Reports Server (NTRS)

Olson, S. L.; Lee, J. R.; Fujita, O.; Kikuchi, M.; Kashiwagi, T.

2013-01-01

The effect of low velocity forced flow on microgravity flame spread is examined using quantitative analysis of infrared video imaging. The objective of the quantitative analysis is to provide insight into the mechanisms of flame spread in microgravity where the flame is able to spread from a central location on the fuel surface, rather than from an edge. Surface view calibrated infrared images of ignition and flame spread over a thin cellulose fuel were obtained along with a color video of the surface view and color images of the edge view using 35 mm color film at 2 Hz. The cellulose fuel samples were mounted in the center of a 12 cm wide by 16 cm tall flow duct and were ignited in microgravity using a straight hot wire across the center of the 7.5 cm wide by 14 cm long samples. Four cases, at 1 atm. 35%O2 in N2, at forced flows from 2 cm/s to 20 cm/s are presented here. This flow range captures flame spread from strictly upstream spread at low flows, to predominantly downstream spread at high flow. Surface temperature profiles are evaluated as a function of time, and temperature gradients for upstream and downstream flame spread are measured. Flame spread rates from IR image data are compared to visible image spread rate data. IR blackbody temperatures are compared to surface thermocouple readings to evaluate the effective emissivity of the pyrolyzing surface. Preheat lengths and pyrolysis lengths are evaluated both upstream and downstream of the central ignition point. A surface energy balance estimates the net heat flux from the flame to the fuel surface along the length of the fuel. Surface radiative loss and gas-phase radiation from soot are measured relative to the net heat feedback from the flame. At high surface heat loss relative to heat feedback, the downstream flame spread does not occur.

Heat transfer measurements for Stirling machine cylinders

NASA Technical Reports Server (NTRS)

Kornhauser, Alan A.; Kafka, B. C.; Finkbeiner, D. L.; Cantelmi, F. C.

1994-01-01

The primary purpose of this study was to measure the effects of inflow-produced heat turbulence on heat transfer in Stirling machine cylinders. A secondary purpose was to provide new experimental information on heat transfer in gas springs without inflow. The apparatus for the experiment consisted of a varying-volume piston-cylinder space connected to a fixed volume space by an orifice. The orifice size could be varied to adjust the level of inflow-produced turbulence, or the orifice plate could be removed completely so as to merge the two spaces into a single gas spring space. Speed, cycle mean pressure, overall volume ratio, and varying volume space clearance ratio could also be adjusted. Volume, pressure in both spaces, and local heat flux at two locations were measured. The pressure and volume measurements were used to calculate area averaged heat flux, heat transfer hysteresis loss, and other heat transfer-related effects. Experiments in the one space arrangement extended the range of previous gas spring tests to lower volume ratio and higher nondimensional speed. The tests corroborated previous results and showed that analytic models for heat transfer and loss based on volume ratio approaching 1 were valid for volume ratios ranging from 1 to 2, a range covering most gas springs in Stirling machines. Data from experiments in the two space arrangement were first analyzed based on lumping the two spaces together and examining total loss and averaged heat transfer as a function of overall nondimensional parameter. Heat transfer and loss were found to be significantly increased by inflow-produced turbulence. These increases could be modeled by appropriate adjustment of empirical coefficients in an existing semi-analytic model. An attempt was made to use an inverse, parameter optimization procedure to find the heat transfer in each of the two spaces. This procedure was successful in retrieving this information from simulated pressure-volume data with artificially

Miniature Heat Pipes

NASA Technical Reports Server (NTRS)

1997-01-01

Small Business Innovation Research contracts from Goddard Space Flight Center to Thermacore Inc. have fostered the company work on devices tagged "heat pipes" for space application. To control the extreme temperature ranges in space, heat pipes are important to spacecraft. The problem was to maintain an 8-watt central processing unit (CPU) at less than 90 C in a notebook computer using no power, with very little space available and without using forced convection. Thermacore's answer was in the design of a powder metal wick that transfers CPU heat from a tightly confined spot to an area near available air flow. The heat pipe technology permits a notebook computer to be operated in any position without loss of performance. Miniature heat pipe technology has successfully been applied, such as in Pentium Processor notebook computers. The company expects its heat pipes to accommodate desktop computers as well. Cellular phones, camcorders, and other hand-held electronics are forsible applications for heat pipes.

Mathematical modeling of the process of determining the standards for process losses in the transfer of thermal energy of the coolant

NASA Astrophysics Data System (ADS)

Akhmetova, I. G.; Chichirova, N. D.

2017-11-01

Currently the actual problem is a precise definition of the normative and actual heat loss. Existing methods - experimental, on metering devices, on the basis of mathematical modeling methods are not without drawbacks. Heat losses establishing during the heat carrier transport has an impact on the tariff structure of heat supply organizations. This quantity determination also promotes proper choice of main and auxiliary equipment power, temperature chart of heat supply networks, as well as the heating system structure choice with the decentralization. Calculation of actual heat loss and their comparison with standard values justifies the performance of works on improvement of the heat networks with the replacement of piping or its insulation. To determine the cause of discrepancies between normative and actual heat losses thermal tests on the magnitude of the actual heat losses in the 124 sections of heat networks in Kazan. As were carried out the result mathematical model of the regulatory definition of heat losses is developed and tested. This model differ from differs the existing according the piping insulation type. The application of this factor will bring the value of calculative normative losses heat energy to their actual value. It is of great importance for enterprises operating distribution networks and because of the conditions of their configuration and extensions do not have the technical ability to produce thermal testing.

Heat Losses from a Breathing System with a Heated-water Humidifier

PubMed Central

Lunn, J. N.; Mapleson, W. W.; Hillard, E. K.

1971-01-01

Air was “breathed” in the laboratory through a heated-water humidifier and a breathing tube. Several different humidifiers and tubes were used. The temperature rise of the air on passing through the humidifier and the temperature drop on passing through the tube were measured. Both were dependent on ventilation. Insulating the tube and humidifier together with the insertion of baffles in the latter reduced the rise and fall and their dependence on ventilation. With suitable design the dependence on ventilation and the need to use high water temperatures could be greatly reduced. In addition, a thermostat with a reduced dead zone is needed. PMID:5289685

Body temperature depression and peripheral heat loss accompany the metabolic and ventilatory responses to hypoxia in low and high altitude birds.

PubMed

Scott, Graham R; Cadena, Viviana; Tattersall, Glenn J; Milsom, William K

2008-04-01

The objectives of this study were to compare the thermoregulatory, metabolic and ventilatory responses to hypoxia of the high altitude bar-headed goose with low altitude waterfowl. All birds were found to reduce body temperature (T(b)) during hypoxia, by up to 1-1.5 degrees C in severe hypoxia. During prolonged hypoxia, T(b) stabilized at a new lower temperature. A regulated increase in heat loss contributed to T(b) depression as reflected by increases in bill surface temperatures (up to 5 degrees C) during hypoxia. Bill warming required peripheral chemoreceptor inputs, since vagotomy abolished this response to hypoxia. T(b) depression could still occur without bill warming, however, because vagotomized birds reduced T(b) as much as intact birds. Compared to both greylag geese and pekin ducks, bar-headed geese required more severe hypoxia to initiate T(b) depression and heat loss from the bill. However, when T(b) depression or bill warming were expressed relative to arterial O(2) concentration (rather than inspired O(2)) all species were similar; this suggests that enhanced O(2) loading, rather than differences in thermoregulatory control centres, reduces T(b) depression during hypoxia in bar-headed geese. Correspondingly, bar-headed geese maintained higher rates of metabolism during severe hypoxia (7% inspired O(2)), but this was only partly due to differences in T(b). Time domains of the hypoxic ventilatory response also appeared to differ between bar-headed geese and low altitude species. Overall, our results suggest that birds can adjust peripheral heat dissipation to facilitate T(b) depression during hypoxia, and that bar-headed geese minimize T(b) and metabolic depression as a result of evolutionary adaptations that enhance O(2) transport.

District heating with geothermally heated culinary water supply systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pitts, D.R.; Schmitt, R.C.

1979-09-01

An initial feasibility study of using existing culinary water supply systems to provide hot water for space heating and air conditioning to a typical residential community is reported. The Phase I study has centered on methods of using low-to-moderate temperature water for heating purposes including institutional barriers, identification and description of a suitable residential commnity water system, evaluation of thermal losses in both the main distribution system and the street mains within the residential district, estimation of size and cost of the pumping station main heat exchanger, sizing of individual residential heat exchangers, determination of pumping and power requirements duemore » to increased flow through the residential area mains, and pumping and power requirements from the street mains through a typical residence. All results of the engineering study of Phase I are encouraging.« less

Proposal for a quantitative index of flood disasters.

PubMed

Feng, Lihua; Luo, Gaoyuan

2010-07-01

Drawing on calculations of wind scale and earthquake magnitude, this paper develops a new quantitative method for measuring flood magnitude and disaster intensity. Flood magnitude is the quantitative index that describes the scale of a flood; the flood's disaster intensity is the quantitative index describing the losses caused. Both indices have numerous theoretical and practical advantages with definable concepts and simple applications, which lend them key practical significance.

24 CFR 3280.707 - Heat producing appliances.

Code of Federal Regulations, 2010 CFR

2010-04-01

... with a comfort heating system. (i) When a manufactured home is manufactured to contain a heating... oil burning comfort heating appliances shall have a flue loss of not more than 25 percent, and a thermal efficiency of not less than that specified in nationally recognized standards (See § 3280.703). (b...

Use of a liquid-crystal, heater-element composite for quantitative, high-resolution heat transfer coefficients on a turbine airfoil, including turbulence and surface roughness effects

NASA Astrophysics Data System (ADS)

Hippensteele, Steven A.; Russell, Louis M.; Torres, Felix J.

1987-05-01

Local heat transfer coefficients were measured along the midchord of a three-times-size turbine vane airfoil in a static cascade operated at roon temperature over a range of Reynolds numbers. The test surface consisted of a composite of commercially available materials: a Mylar sheet with a layer of cholestric liquid crystals, which change color with temperature, and a heater made of a polyester sheet coated with vapor-deposited gold, which produces uniform heat flux. After the initial selection and calibration of the composite sheet, accurate, quantitative, and continuous heat transfer coefficients were mapped over the airfoil surface. Tests were conducted at two free-stream turbulence intensities: 0.6 percent, which is typical of wind tunnels; and 10 percent, which is typical of real engine conditions. In addition to a smooth airfoil, the effects of local leading-edge sand roughness were also examined for a value greater than the critical roughness. The local heat transfer coefficients are presented for both free-stream turbulence intensities for inlet Reynolds numbers from 1.20 to 5.55 x 10 to the 5th power. Comparisons are also made with analytical values of heat transfer coefficients obtained from the STAN5 boundary layer code.

Use of a liquid-crystal, heater-element composite for quantitative, high-resolution heat transfer coefficients on a turbine airfoil, including turbulence and surface roughness effects

NASA Technical Reports Server (NTRS)

Hippensteele, Steven A.; Russell, Louis M.; Torres, Felix J.

1987-01-01

Local heat transfer coefficients were measured along the midchord of a three-times-size turbine vane airfoil in a static cascade operated at roon temperature over a range of Reynolds numbers. The test surface consisted of a composite of commercially available materials: a Mylar sheet with a layer of cholestric liquid crystals, which change color with temperature, and a heater made of a polyester sheet coated with vapor-deposited gold, which produces uniform heat flux. After the initial selection and calibration of the composite sheet, accurate, quantitative, and continuous heat transfer coefficients were mapped over the airfoil surface. Tests were conducted at two free-stream turbulence intensities: 0.6 percent, which is typical of wind tunnels; and 10 percent, which is typical of real engine conditions. In addition to a smooth airfoil, the effects of local leading-edge sand roughness were also examined for a value greater than the critical roughness. The local heat transfer coefficients are presented for both free-stream turbulence intensities for inlet Reynolds numbers from 1.20 to 5.55 x 10 to the 5th power. Comparisons are also made with analytical values of heat transfer coefficients obtained from the STAN5 boundary layer code.

A novel experimental setup for energy loss and charge state measurements in dense moderately coupled plasma using laser-heated hohlraum targets

NASA Astrophysics Data System (ADS)

Ortner, A.; Schumacher, D.; Cayzac, W.; Frank, A.; Basko, M. M.; Bedacht, S.; Blazevic, A.; Faik, S.; Kraus, D.; Rienecker, T.; Schaumann, G.; Tauschwitz, An.; Wagner, F.; Roth, M.

2016-03-01

We report on a new experimental setup for ion energy loss measurements in dense moderately coupled plasma which has recently been developed and tested at GSI Darmstadt. A partially ionized, moderately coupled carbon plasma (ne ≤ 0.8• 1022 cm-3, Te = 15 eV, z = 2.5, Γ = 0.5) is generated by volumetrical heating of two thin carbon foils with soft X-rays. This plasma is then probed by a bunched heavy ion beam. For that purpose, a special double gold hohlraum target of sub-millimeter size has been developed which efficiently converts intense laser light into thermal radiation and guarantees a gold-free interaction path for the ion beam traversing the carbon plasma. This setup allows to do precise energy loss measurements in non-ideal plasma at the level of 10 percent solid-state density.

High heat flux loop heat pipes

NASA Astrophysics Data System (ADS)

North, Mark T.; Sarraf, David B.; Rosenfeld, John H.; Maidanik, Yuri F.; Vershinin, Sergey

1997-01-01

Loop Heat Pipes (LHPs) can transport very large thermal power loads, over long distances, through flexible, small diameter tubes and against high gravitational heads. While recent LHPs have transported as much as 1500 W, the peak heat flux through a LHP's evaporator has been limited to about 0.07 MW/m2. This limitation is due to the arrangement of vapor passages next to the heat load which is one of the conditions necessary to ensure self priming of the device. This paper describes work aimed at raising this limit by threefold to tenfold. Two approaches were pursued. One optimized the vapor passage geometry for the high heat flux conditions. The geometry improved the heat flow into the wick and working fluid. This approach also employed a finer pored wick to support higher vapor flow losses. The second approach used a bidisperse wick material within the circumferential vapor passages. The bidisperse material increased the thermal conductivity and the evaporative surface area in the region of highest heat flux, while providing a flow path for the vapor. Proof-of-concept devices were fabricated and tested for each approach. Both devices operated as designed and both demonstrated operation at a heat flux of 0.70 MW/m2. This performance exceeded the known state of the art by a factor of more than six for both conventional heat pipes and for loop heat pipes using ammonia. In addition, the bidisperse-wick device demonstrated boiling heat transfer coefficients up to 100,000 W/m2.K, and the fine pored device demonstrated an orientation independence with its performance essentially unaffected by whether its evaporator was positioned above, below or level with the condenser.

Avian thermoregulation in the heat: resting metabolism, evaporative cooling and heat tolerance in Sonoran Desert songbirds.

PubMed

Smith, Eric Krabbe; O'Neill, Jacqueline J; Gerson, Alexander R; McKechnie, Andrew E; Wolf, Blair O

2017-09-15

We examined thermoregulatory performance in seven Sonoran Desert passerine bird species varying in body mass from 10 to 70 g - lesser goldfinch, house finch, pyrrhuloxia, cactus wren, northern cardinal, Abert's towhee and curve-billed thrasher. Using flow-through respirometry, we measured daytime resting metabolism, evaporative water loss and body temperature at air temperatures ( T air ) between 30 and 52°C. We found marked increases in resting metabolism above the upper critical temperature ( T uc ), which for six of the seven species fell within a relatively narrow range (36.2-39.7°C), but which was considerably higher in the largest species, the curve-billed thrasher (42.6°C). Resting metabolism and evaporative water loss were minimal below the T uc and increased with T air and body mass to maximum values among species of 0.38-1.62 W and 0.87-4.02 g H 2 O h -1 , respectively. Body temperature reached maximum values ranging from 43.5 to 45.3°C. Evaporative cooling capacity, the ratio of evaporative heat loss to metabolic heat production, reached maximum values ranging from 1.39 to 2.06, consistent with known values for passeriforms and much lower than values in taxa such as columbiforms and caprimulgiforms. These maximum values occurred at heat tolerance limits that did not scale with body mass among species, but were ∼50°C for all species except the pyrrhuloxia and Abert's towhee (48°C). High metabolic costs associated with respiratory evaporation appeared to drive the limited heat tolerance in these desert passeriforms, compared with larger desert columbiforms and galliforms that use metabolically more efficient mechanisms of evaporative heat loss. © 2017. Published by The Company of Biologists Ltd.

Standard Reference Line Combined with One-Point Calibration-Free Laser-Induced Breakdown Spectroscopy (CF-LIBS) to Quantitatively Analyze Stainless and Heat Resistant Steel.

PubMed

Fu, Hongbo; Wang, Huadong; Jia, Junwei; Ni, Zhibo; Dong, Fengzhong

2018-01-01

Due to the influence of major elements' self-absorption, scarce observable spectral lines of trace elements, and relative efficiency correction of experimental system, accurate quantitative analysis with calibration-free laser-induced breakdown spectroscopy (CF-LIBS) is in fact not easy. In order to overcome these difficulties, standard reference line (SRL) combined with one-point calibration (OPC) is used to analyze six elements in three stainless-steel and five heat-resistant steel samples. The Stark broadening and Saha - Boltzmann plot of Fe are used to calculate the electron density and the plasma temperature, respectively. In the present work, we tested the original SRL method, the SRL with the OPC method, and intercept with the OPC method. The final calculation results show that the latter two methods can effectively improve the overall accuracy of quantitative analysis and the detection limits of trace elements.

Utilization of waste heat from aluminium electrolytic cell

NASA Astrophysics Data System (ADS)

Nosek, Radovan; Gavlas, Stanislav; Lenhard, Richard; Malcho, Milan; Sedlak, Veroslav; Teie, Sebastian

2017-12-01

During the aluminium production, 50% of the supplied energy is consumed by the chemical process, and 50% of the supplied energy is lost in form of heat. Heat losses are necessary to maintain a frozen side ledge to protect the side walls, so extra heat has to be wasted. In order to increase the energy efficiency of the process, it is necessary to significantly lower the heat losses dissipated by the furnace's external surface. Goodtech Recovery Technology (GRT) has developed a technology based on the use of heat pipes for utilization energy from the waste heat produced in the electrolytic process. Construction of condenser plays important role for efficient operation of energy systems. The condensation part of the heat pipe is situated on top of the heating zone. The thermal oil is used as cooling medium in the condenser. This paper analyses the effect of different operation condition of thermal oil to thermal performance. From the collected results it is obvious that the larger mass flow and higher temperature cause better thermal performance and lower pressure drop.

Diaphragm Stirling engine heat-actuated heat pump development

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ackermann, R.A.; Swenson, P.

1981-01-01

The objective of this program is to develop and demonstrate the performance of a diaphragm Stirling engine heat-actuated heat pump power module. The power module, consisting of a free displacer, resonant Stirling engine, hydraulic transmission, and resonant Rankine refrigerant (F-22) compressor, embodies several innovative concepts in free-piston Stirling engine heat pump design that will advance the state of the art of this technology. Progress is reported in three areas of the program. First, a compressor/engine matching analysis and a stability analysis have shown that the power module, which is representative of a two-degree-of-freedom resonant system, will operate stably over themore » full range of heat pump conditions. Second, a compressor design has evolved that has met criteria for performance and cost; and third, tests employing a hydraulic simulator test rig has shown that the transmission losses are less than had been predicted, and that properly designed and fabricated diaphragms can attain long life.« less

Are All Heat Loads Created Equal?

PubMed

Meade, Robert D; Kenny, Glen P

2017-09-01

We evaluated physiological responses during exercise at a fixed evaporative requirement for heat balance (Ereq) but varying combinations of metabolic and environmental heat load. Nine healthy, physically active males (age: 46 ± 8 yr) performed four experimental sessions consisting of 75 min of semirecumbent cycling at various ambient temperatures. Whole-body dry heat loss (direct calorimetry) was monitored continuously as was heat production (indirect calorimetry), which was adjusted to achieve an Ereq of 400 W. The resultant metabolic heat productions and ambient temperatures for the sessions were as follows: (i) 440 W and 30°C (440 [30]), (ii) 388 W and 35°C (388 [35]), (iii) 317 W and 40°C (317 [40]), and (iv) 258 W and 45°C (258 [45]). Whole-body evaporative heat loss was determined via direct calorimetry. Esophageal (Tes) and mean skin (Tsk) temperatures as well as HR were monitored continuously. Mean body temperature (Tb) was calculated from Tes and Tsk. Physiological strain index (PSI) was determined from Tes and HR. End-exercise evaporative heat loss and Tb were similar between conditions (both P ≥ 0.48). Tes was greater in 440 [30] (37.67°C ± 0.04°C) and 388 [35] (37.58°C ± 0.07°C) relative to both 317 [40] (37.35°C ± 0.06°C) and 258 [45] (37.20°C ± 0.07°C; all P ≤ 0.05). Further, Tsk was different between each condition (440 [30], 33.85°C ± 0.16°C; 388 [35], 34.53°C ± 0.08°C; 317 [40], 35.67°C ± 0.07°C; and 258 [45], 36.54°C ± 0.08°C; all P < 0.01). In 440 [30], HR was elevated by about 13 and 18 bpm relative to 317 [40] and 258 [45], respectively (both P < 0.01). Finally, PSI was greater in both 440 [30] and 388 [35] compared with 317 [40] and 258 [45] (all P ≤ 0.04). Exercise at a fixed Ereq resulted in similar evaporative heat loss and Tb. However, the Tes, Tsk, HR, and PSI responses varied depending on the relative contribution of metabolic and environmental heat load.

Regulation of Heat Exchange across the Hornbill Beak: Functional Similarities with Toucans?

PubMed

van de Ven, T M F N; Martin, R O; Vink, T J F; McKechnie, A E; Cunningham, S J

2016-01-01

Beaks are increasingly recognised as important contributors to avian thermoregulation. Several studies supporting Allen's rule demonstrate how beak size is under strong selection related to latitude and/or air temperature (Ta). Moreover, active regulation of heat transfer from the beak has recently been demonstrated in a toucan (Ramphastos toco, Ramphastidae), with the large beak acting as an important contributor to heat dissipation. We hypothesised that hornbills (Bucerotidae) likewise use their large beaks for non-evaporative heat dissipation, and used thermal imaging to quantify heat exchange over a range of air temperatures in eighteen desert-living Southern Yellow-billed Hornbills (Tockus leucomelas). We found that hornbills dissipate heat via the beak at air temperatures between 30.7°C and 41.4°C. The difference between beak surface and environmental temperatures abruptly increased when air temperature was within ~10°C below body temperature, indicating active regulation of heat loss. Maximum observed heat loss via the beak was 19.9% of total non-evaporative heat loss across the body surface. Heat loss per unit surface area via the beak more than doubled at Ta > 30.7°C compared to Ta < 30.7°C and at its peak dissipated 25.1 W m-2. Maximum heat flux rate across the beak of toucans under comparable convective conditions was calculated to be as high as 61.4 W m-2. The threshold air temperature at which toucans vasodilated their beak was lower than that of the hornbills, and thus had a larger potential for heat loss at lower air temperatures. Respiratory cooling (panting) thresholds were also lower in toucans compared to hornbills. Both beak vasodilation and panting threshold temperatures are potentially explained by differences in acclimation to environmental conditions and in the efficiency of evaporative cooling under differing environmental conditions. We speculate that non-evaporative heat dissipation may be a particularly important mechanism for

Regulation of Heat Exchange across the Hornbill Beak: Functional Similarities with Toucans?

PubMed Central

Martin, R. O.; Vink, T. J. F.; McKechnie, A. E.; Cunningham, S. J.

2016-01-01

Beaks are increasingly recognised as important contributors to avian thermoregulation. Several studies supporting Allen’s rule demonstrate how beak size is under strong selection related to latitude and/or air temperature (Ta). Moreover, active regulation of heat transfer from the beak has recently been demonstrated in a toucan (Ramphastos toco, Ramphastidae), with the large beak acting as an important contributor to heat dissipation. We hypothesised that hornbills (Bucerotidae) likewise use their large beaks for non-evaporative heat dissipation, and used thermal imaging to quantify heat exchange over a range of air temperatures in eighteen desert-living Southern Yellow-billed Hornbills (Tockus leucomelas). We found that hornbills dissipate heat via the beak at air temperatures between 30.7°C and 41.4°C. The difference between beak surface and environmental temperatures abruptly increased when air temperature was within ~10°C below body temperature, indicating active regulation of heat loss. Maximum observed heat loss via the beak was 19.9% of total non-evaporative heat loss across the body surface. Heat loss per unit surface area via the beak more than doubled at Ta > 30.7°C compared to Ta < 30.7°C and at its peak dissipated 25.1 W m-2. Maximum heat flux rate across the beak of toucans under comparable convective conditions was calculated to be as high as 61.4 W m-2. The threshold air temperature at which toucans vasodilated their beak was lower than that of the hornbills, and thus had a larger potential for heat loss at lower air temperatures. Respiratory cooling (panting) thresholds were also lower in toucans compared to hornbills. Both beak vasodilation and panting threshold temperatures are potentially explained by differences in acclimation to environmental conditions and in the efficiency of evaporative cooling under differing environmental conditions. We speculate that non-evaporative heat dissipation may be a particularly important mechanism for

Opportunities for Waste Heat Recovery at Contingency Bases

DTIC Science & Technology

2016-04-01

thermal insulation around the reactor to reduce heating requirements. Calculations demonstrate that about 44 W-hrs are required to heat a gallon of...tank ( ), which considers the convective heat transfer inside and outside the tank, the tank material, and insulation surrounding...well as provide excellent insulation to reduce heat loss during transport. Any non-buried portion (e.g., at tank or heat exchanger connec- tions

Observation of alpha particle loss from JET plasmas during ion cyclotron resonance frequency heating using a thin foil Faraday cup detector array.

PubMed

Darrow, D S; Cecil, F E; Kiptily, V; Fullard, K; Horton, A; Murari, A

2010-10-01

The loss of MeV alpha particles from JET plasmas has been measured with a set of thin foil Faraday cup detectors during third harmonic heating of helium neutral beam ions. Tail temperatures of ∼ 2 MeV have been observed, with radial scrape off lengths of a few centimeters. Operational experience from this system indicates that such detectors are potentially feasible for future large tokamaks, but careful attention to screening rf and MHD induced noise is essential.

[Comparative evaluation of heat state in workers exposed to heating microclimate during cold and warm seasons].

PubMed

Afanas'eva, R F; Prokopenko, L V; Kiladze, N A; Konstantinov, E I

2009-01-01

The authors demonstrated differences in heat state among workers exposed to heating microclimate during cold and warm seasons. Same external thermal load in cold season induces more humidity loss, lower weighted average skin temperature, higher pulse rate, increased systolic and diastolic blood pressure. With that, heat discomfort was more in cold season, than in warm one, this necessitates decrease of thermal load in cold season vs. the warm one.

Quantitative analysis of the local phase transitions induced by the laser heating

DOE PAGES

Levlev, Anton V.; Susner, Michael A.; McGuire, Michael A.; ...

2015-11-04

Functional imaging enabled by scanning probe microscopy (SPM) allows investigations of nanoscale material properties under a wide range of external conditions, including temperature. However, a number of shortcomings preclude the use of the most common material heating techniques, thereby limiting precise temperature measurements. Here we discuss an approach to local laser heating on the micron scale and its applicability for SPM. We applied local heating coupled with piezoresponse force microscopy and confocal Raman spectroscopy for nanoscale investigations of a ferroelectric-paraelectric phase transition in the copper indium thiophosphate layered ferroelectric. Bayesian linear unmixing applied to experimental results allowed extraction of themore » Raman spectra of different material phases and enabled temperature calibration in the heated region. Lastly, the obtained results enable a systematic approach for studying temperature-dependent material functionalities in heretofore unavailable temperature regimes.« less

Quantitative evaluation of spatial scale of carrier trapping at grain boundary by GHz-microwave dielectric loss spectroscopy

NASA Astrophysics Data System (ADS)

Choi, W.; Tsutsui, Y.; Miyakai, T.; Sakurai, T.; Seki, S.

2017-11-01

Charge carrier mobility is an important primary parameter for the electronic conductive materials, and the intrinsic limit of the mobility has been hardly access by conventional direct-current evaluation methods. In the present study, intra-grain hole mobility of pentacene thin films was estimated quantitatively using microwave-based dielectric loss spectroscopy (time-resolved microwave conductivity measurement) in alternating current mode of charge carrier local motion. Metal-insulator-semiconductor devices were prepared with different insulating polymers or substrate temperature upon vacuum deposition of the pentacene layer, which afforded totally four different grain-size conditions of pentacene layers. Under the condition where the local motion was determined by interfacial traps at the pentacene grain boundaries (grain-grain interfaces), the observed hole mobilities were plotted against the grain sizes, giving an excellent correlation fit successfully by a parabolic function representative of the boarder length. Consequently, the intra-grain mobility and trap-release time of holes were estimated as 15 cm2 V-1 s-1 and 9.4 ps.

Quantitative determination of optical and recombination losses in thin-film photovoltaic devices based on external quantum efficiency analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nakane, Akihiro; Tamakoshi, Masato; Fujimoto, Shohei

2016-08-14

In developing photovoltaic devices with high efficiencies, quantitative determination of the carrier loss is crucial. In conventional solar-cell characterization techniques, however, photocurrent reduction originating from parasitic light absorption and carrier recombination within the light absorber cannot be assessed easily. Here, we develop a general analysis scheme in which the optical and recombination losses in submicron-textured solar cells are evaluated systematically from external quantum efficiency (EQE) spectra. In this method, the optical absorption in solar cells is first deduced by imposing the anti-reflection condition in the calculation of the absorptance spectrum, and the carrier extraction from the light absorber layer ismore » then modeled by considering a carrier collection length from the absorber interface. Our analysis method is appropriate for a wide variety of photovoltaic devices, including kesterite solar cells [Cu{sub 2}ZnSnSe{sub 4}, Cu{sub 2}ZnSnS{sub 4}, and Cu{sub 2}ZnSn(S,Se){sub 4}], zincblende CdTe solar cells, and hybrid perovskite (CH{sub 3}NH{sub 3}PbI{sub 3}) solar cells, and provides excellent fitting to numerous EQE spectra reported earlier. Based on the results obtained from our EQE analyses, we discuss the effects of parasitic absorption and carrier recombination in different types of solar cells.« less

Comparison of experimental with theoretical total-pressure loss in parallel-walled turbojet combustors

NASA Technical Reports Server (NTRS)

Dittrich, Ralph T

1957-01-01

An experimental investigation of combustor total-pressure loss was undertaken to confirm previous theoretical analyses of effects of geometric and flow variables and of heat addition. The results indicate that a reasonable estimate of cold-flow total-pressure-loss coefficient may be obtained from the theoretical analyses. Calculated total-pressure loss due to heat addition agreed with experimental data only when there was no flame ejection from the liner at the upstream air-entry holes.

Stress and Grief of a Perinatal Loss: Integrating Qualitative and Quantitative Methods.

ERIC Educational Resources Information Center

Thomas, Volker; Striegel, Phil

1995-01-01

Examined how parents grieve loss of a baby through miscarriage or stillbirth. Interviewed 26 couples 2 weeks after a perinatal loss. Ethnographic content analysis revealed 12 themes closely related to resources, meaning of the stressful event, and coping strategies, all of which are elements, of Hill's ABC-X stress model. (JBJ)

Full wave simulations of fast wave efficiency and power losses in the scrape-off layer of tokamak plasmas in mid/high harmonic and minority heating regimes

DOE PAGES

Bertelli, N.; Jaeger, E. F.; Hosea, J. C.; ...

2015-12-17

Here, several experiments on different machines and in different fast wave (FW) heating regimes, such as hydrogen minority heating and high harmonic fast waves (HHFW), have found strong interaction between radio-frequency (RF) waves and the scrape-off layer (SOL) region. This paper examines the propagation and the power loss in the SOL by using the full wave code AORSA, in which the edge plasma beyond the last closed flux surface (LCFS) is included in the solution domain and a collisional damping parameter is used as a proxy to represent the real, and most likely nonlinear, damping processes. 2D and 3D AORSAmore » results for the National Spherical Torus eXperiment (NSTX) have shown a strong transition to higher SOL power losses (driven by the RF field) when the FW cut-off is removed from in front of the antenna by increasing the edge density. Here, full wave simulations have been extended for 'conventional' tokamaks with higher aspect ratios, such as the DIII-D, Alcator C-Mod, and EAST devices. DIII-D results in HHFW regime show similar behavior found in NSTX and NSTX-U, consistent with previous DIII-D experimental observations. In contrast, a different behavior has been found for C-Mod and EAST, which operate in the minority heating regime.« less

Geometrical effects on the concentrated behavior of heat flux in metamaterials thermal harvesting devices

NASA Astrophysics Data System (ADS)

Xu, Guoqiang; Zhang, Haochun; Xie, Ming; Jin, Yan

2017-10-01

Thermal harvesting devices based on transformation optics, which can manipulate the heat flux concentration significantly through rational arrangements of the conductivities, have attracted considerable interest owing to several great potential applications of the technique for high-efficiency thermal conversion and collection. However, quantitative studies on the geometrical effects, particularly wedge angles, on the harvesting behaviors are rare. In this paper, we adopt wedge structure-based thermal harvesting schemes, and focus on the effects of the geometrical parameters including the radii ratios and wedge angles on the harvesting performance. The temperature deformations at the boundaries of the compressional region and temperature gradients for the different schemes with varying design parameters are investigated. Moreover, a concept for temperature stabilization was derived to evaluate the fluctuation in the energy distributions. In addition, the effects of interface thermal resistances have been investigated. Considering the changes in the radii ratios and wedge angles, we proposed a modification of the harvesting efficiency to quantitatively assess the concentration performance, which was verified through random tests and previously fabricated devices. In general, this study indicates that a smaller radii ratio contributes to a better harvesting behavior, but causes larger perturbations in the thermal profiles owing to a larger heat loss. We also find that a smaller wedge angle is beneficial to ensuring a higher concentration efficiency with less energy perturbations. These findings can be used to guide the improvement of a thermal concentrator with a high efficiency in reference to its potential applications as novel heat storage, thermal sensors, solar cells, and thermoelectric devices.

Using single-step genomic best linear unbiased predictor to enhance the mitigation of seasonal losses due to heat stress in pigs.

PubMed

Fragomeni, B O; Lourenco, D A L; Tsuruta, S; Bradford, H L; Gray, K A; Huang, Y; Misztal, I

2016-12-01

The purposes of this study were to analyze the impact of seasonal losses due to heat stress in pigs from different breeds raised in different environments and to evaluate the accuracy improvement from adding genomic information to genetic evaluations. Data were available for 2 different swine populations: purebred Duroc animals raised in Texas and North Carolina and commercial crosses of Duroc and F females (Landrace × Large White) raised in Missouri and North Carolina; pedigrees provided links for animals from different states. Pedigree information was available for 553,442 animals, of which 8,232 pure breeds were genotyped. Traits were BW at 170 d for purebred animals and HCW for crossbred animals. Analyses were done with an animal model as either single- or 2-trait models using phenotypes measured in different states as separate traits. Additionally, reaction norm models were fitted for 1 or 2 traits using heat load index as a covariable. Heat load was calculated as temperature-humidity index greater than 70 and was averaged over 30 d prior to data collection. Variance components were estimated with average information REML, and EBV and genomic EBV (GEBV) with BLUP or single-step genomic BLUP (ssGBLUP). Validation was assessed for 146 genotyped sires with progeny in the last generation. Accuracy was calculated as a correlation between EBV and GEBV using reduced data (all animals, except the last generation) and using complete data. Heritability estimates for purebred animals were similar across states (varying from 0.23 to 0.26), and reaction norm models did not show evidence of a heat stress effect. Genetic correlations between states for heat loads were always strong (>0.91). For crossbred animals, no differences in heritability were found in single- or 2-trait analysis (from 0.17 to 0.18), and genetic correlations between states were moderate (0.43). In the reaction norm for crossbreeds, heritabilities ranged from 0.15 to 0.30 and genetic correlations

Heat shock protein 70 as a biomarker of heat stress in a simulated hot cockpit.

PubMed

Kumar, Yadunanda; Chawla, Anuj; Tatu, Utpal

2003-07-01

Fighter pilots are frequently exposed to high temperatures during high-speed low-level flight. Heat strain can result in temporary impairment of cognitive functions and when severe, loss of consciousness and consequent loss of life and equipment. Induction of stress proteins is a highly conserved stress response mechanism from bacteria to humans. Induced stress protein levels are known to be cytoprotective and have been correlated with stress tolerance. Although many studies on the heat shock response mechanisms have been performed in cell culture and animal model systems, there is very limited information on stress protein induction in human subjects. Heat shock proteins (Hsp), especially Hsp70, may be induced in human subjects exposed to high temperatures in a hot cockpit designed to simulate heat stress experienced in low flying sorties. Six healthy volunteers were subjected to heat stress at 55 degrees C in a high temperature cockpit simulator for a period of 1 h at 30% humidity. Physiological parameters such as oral and skin temperatures, heart rate, and sweat rate were monitored regularly during this time. The level of Hsp70 in leukocytes was examined before and after the heat exposure in each subject. Hsp70 was found to be significantly induced in all the six subjects exposed to heat stress. The level of induced Hsp70 appears to correlate with other strain indicators such as accumulative circulatory strain and Craig's modified index. The usefulness of Hsp70 as a molecular marker of heat stress in humans is discussed.

Use of a liquid-crystal and heater-element composite for quantitative, high-resolution heat-transfer coefficients on a turbine airfoil including turbulence and surface-roughness effects

NASA Astrophysics Data System (ADS)

Hippensteele, S. A.; Russell, L. M.; Torres, F. J.

Local heat transfer coefficients were measured along the midchord of a three-times-size turbine vane airfoil in a static cascade operated at room temperature over a range of Reynolds numbers. The test surface consisted of a composite of commercially available materials: a Mylar sheet with a layer of cholestric liquid crystals, which change color with temperature, and a heater made of a polyester sheet coated with vapor-deposited gold, which produces uniform heat flux. After the initial selection and calibration of the composite sheet, accurate, quantitative, and continuous heat transfer coefficients were mapped over the airfoil surface. Tests were conducted at two free-stream turbulence intensities: 0.6 percent, which is typical of wind tunnels; and 10 percent, which is typical of real engine conditions. In addition to a smooth airfoil, the effects of local leading-edge sand roughness were also examined for a value greater than the critical roughness. The local heat transfer coefficients are presented for both free-stream turbulence intensities for inlet Reynolds numbers from 1.20 to 5.55 x 10 to the 5th power. Comparisons are also made with analytical values of heat transfer coefficients obtained from the STAN5 boundary layer code.

A QTL on the short arm of wheat (Triticum aestivum L.) chromosome 3B affects the stability of grain weight in plants exposed to a brief heat shock early in grain filling.

PubMed

Shirdelmoghanloo, Hamid; Taylor, Julian D; Lohraseb, Iman; Rabie, Huwaida; Brien, Chris; Timmins, Andy; Martin, Peter; Mather, Diane E; Emebiri, Livinus; Collins, Nicholas C

2016-04-22

Molecular markers and knowledge of traits associated with heat tolerance are likely to provide breeders with a more efficient means of selecting wheat varieties able to maintain grain size after heat waves during early grain filling. A population of 144 doubled haploids derived from a cross between the Australian wheat varieties Drysdale and Waagan was mapped using the wheat Illumina iSelect 9,000 feature single nucleotide polymorphism marker array and used to detect quantitative trait loci for heat tolerance of final single grain weight and related traits. Plants were subjected to a 3 d heat treatment (37 °C/27 °C day/night) in a growth chamber at 10 d after anthesis and trait responses calculated by comparison to untreated control plants. A locus for single grain weight stability was detected on the short arm of chromosome 3B in both winter- and autumn-sown experiments, determining up to 2.5 mg difference in heat-induced single grain weight loss. In one of the experiments, a locus with a weaker effect on grain weight stability was detected on chromosome 6B. Among the traits measured, the rate of flag leaf chlorophyll loss over the course of the heat treatment and reduction in shoot weight due to heat were indicators of loci with significant grain weight tolerance effects, with alleles for grain weight stability also conferring stability of chlorophyll ('stay-green') and shoot weight. Chlorophyll loss during the treatment, requiring only two non-destructive readings to be taken, directly before and after a heat event, may prove convenient for identifying heat tolerant germplasm. These results were consistent with grain filling being limited by assimilate supply from the heat-damaged photosynthetic apparatus, or alternatively, accelerated maturation in the grains that was correlated with leaf senescence responses merely due to common genetic control of senescence responses in the two organs. There was no evidence for a role of mobilized stem reserves (water

Glove thermal insulation: local heat transfer measures and relevance.

PubMed

Sari, Hayet; Gartner, Maurice; Hoeft, Alain; Candas, Victor

2004-09-01

When exposed to cold, the hands need to be protected against heat loss not only in order to reduce thermal discomfort, but also to keep their efficiency. Although gloves are usually the most common protection, their thermal insulation is generally unknown. The aim of this study was to measure the heat losses from a gloved hand with a special interest in local variations. Using a calorimetric hand placed in a cold box, several types of gloves were tested. The results indicated that depending on the glove and on the area covered the heat loss reduction may vary from almost 60% to 90%. When the least efficient pair of gloves was excluded, heat exchange coefficients varied from 1.8 to 4.8 W/m2 per degrees C for the palm and from 4.2 to 6.2 W/m2 per degrees C for the back of the hand. The three medium fingers seemed to be equally treated, with a heat exchange coefficient variation of 6.3-9.0 W/m2 per degrees C. The thumb and the little finger, which require better insulation, exhibited higher local heat transfer coefficients of 8.3-12.7 W/m2 per degrees C. Some practical aspects are evoked.

Teaching Children with Hearing Loss in Reading Recovery

ERIC Educational Resources Information Center

Charlesworth, Ann; Charlesworth, Robert; Raban, Bridie; Rickards, Field

2006-01-01

This study quantitatively analyzed the structure of Reading Recovery lessons for children with hearing loss by examining and comparing the supportive interactions of three Reading Recovery teachers of 12 children with hearing loss and three Reading Recovery teachers of 12 hearing children. All of the children were in the second year of primary…

Emergency heat removal system for a nuclear reactor

DOEpatents

Dunckel, Thomas L.

1976-01-01

A heat removal system for nuclear reactors serving as a supplement to an Emergency Core Cooling System (ECCS) during a Loss of Coolant Accident (LOCA) comprises a plurality of heat pipes having one end in heat transfer relationship with either the reactor pressure vessel, the core support grid structure or other in-core components and the opposite end located in heat transfer relationship with a heat exchanger having heat transfer fluid therein. The heat exchanger is located external to the pressure vessel whereby excessive core heat is transferred from the above reactor components and dissipated within the heat exchanger fluid.

Entropy Generation/Availability Energy Loss Analysis Inside MIT Gas Spring and "Two Space" Test Rigs

NASA Technical Reports Server (NTRS)

Ebiana, Asuquo B.; Savadekar, Rupesh T.; Patel, Kaushal V.

2006-01-01

The results of the entropy generation and availability energy loss analysis under conditions of oscillating pressure and oscillating helium gas flow in two Massachusetts Institute of Technology (MIT) test rigs piston-cylinder and piston-cylinder-heat exchanger are presented. Two solution domains, the gas spring (single-space) in the piston-cylinder test rig and the gas spring + heat exchanger (two-space) in the piston-cylinder-heat exchanger test rig are of interest. Sage and CFD-ACE+ commercial numerical codes are used to obtain 1-D and 2-D computer models, respectively, of each of the two solution domains and to simulate the oscillating gas flow and heat transfer effects in these domains. Second law analysis is used to characterize the entropy generation and availability energy losses inside the two solution domains. Internal and external entropy generation and availability energy loss results predicted by Sage and CFD-ACE+ are compared. Thermodynamic loss analysis of simple systems such as the MIT test rigs are often useful to understand some important features of complex pattern forming processes in more complex systems like the Stirling engine. This study is aimed at improving numerical codes for the prediction of thermodynamic losses via the development of a loss post-processor. The incorporation of loss post-processors in Stirling engine numerical codes will facilitate Stirling engine performance optimization. Loss analysis using entropy-generation rates due to heat and fluid flow is a relatively new technique for assessing component performance. It offers a deep insight into the flow phenomena, allows a more exact calculation of losses than is possible with traditional means involving the application of loss correlations and provides an effective tool for improving component and overall system performance.

Pungency Quantitation of Hot Pepper Sauces Using HPLC

NASA Astrophysics Data System (ADS)

Betts, Thomas A.

1999-02-01

A class of compounds known as capsaicinoids are responsible for the "heat" of hot peppers. To determine the pungency of a particular pepper or pepper product, one may quantify the capsaicinoids and relate those concentrations to the perceived heat. The format of the laboratory described here allows students to collectively develop an HPLC method for the quantitation of the two predominant capsaicinoids (capsaicin and dihydrocapsaicin) in hot-pepper products. Each small group of students investigated one of the following aspects of the method: detector wavelength, mobile-phase composition, extraction of capsaicinoids, calibration, and quantitation. The format of the lab forced students to communicate and cooperate to develop this method. The resulting HPLC method involves extraction with acetonitrile followed by solid-phase extraction clean-up, an isocratic 80:20 methanol-water mobile phase, a 4.6 mm by 25 cm C-18 column, and UV absorbance detection at 284 nm. The method developed by the students was then applied to the quantitation of capsaicinoids in a variety of hot pepper sauces. Editor's Note on Hazards in our April 2000 issue addresses the above.

Quantitative Thermochronology

NASA Astrophysics Data System (ADS)

Braun, Jean; van der Beek, Peter; Batt, Geoffrey

2006-05-01

Thermochronology, the study of the thermal history of rocks, enables us to quantify the nature and timing of tectonic processes. Quantitative Thermochronology is a robust review of isotopic ages, and presents a range of numerical modeling techniques to allow the physical implications of isotopic age data to be explored. The authors provide analytical, semi-analytical, and numerical solutions to the heat transfer equation in a range of tectonic settings and under varying boundary conditions. They then illustrate their modeling approach built around a large number of case studies. The benefits of different thermochronological techniques are also described. Computer programs on an accompanying website at www.cambridge.org/9780521830577 are introduced through the text and provide a means of solving the heat transport equation in the deforming Earth to predict the ages of rocks and compare them directly to geological and geochronological data. Several short tutorials, with hints and solutions, are also included. Numerous case studies help geologists to interpret age data and relate it to Earth processes Essential background material to aid understanding and using thermochronological data Provides a thorough treatise on numerical modeling of heat transport in the Earth's crust Supported by a website hosting relevant computer programs and colour slides of figures from the book for use in teaching

Code Development and Assessment for Reactor Outage Thermal-Hydraulic and Safety Analysis - Midloop Operation with Loss of Residual Heat Removal

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liang, Thomas K.S.; Ko, F.-K

Although only a few percent of residual power remains during plant outages, the associated risk of core uncovery and corresponding fuel overheating has been identified to be relatively high, particularly under midloop operation (MLO) in pressurized water reactors. However, to analyze the system behavior during outages, the tools currently available, such as RELAP5, RETRAN, etc., cannot easily perform the task. Therefore, a medium-sized program aiming at reactor outage simulation and evaluation, such as MLO with the loss of residual heat removal (RHR), was developed. All important thermal-hydraulic processes involved during MLO with the loss of RHR will be properly simulatedmore » by the newly developed reactor outage simulation and evaluation (ROSE) code. Important processes during MLO with loss of RHR involve a pressurizer insurge caused by the hot-leg flooding, reflux condensation, liquid holdup inside the steam generator, loop-seal clearance, core-level depression, etc. Since the accuracy of the pressure distribution from the classical nodal momentum approach will be degraded when the system is stratified and under atmospheric pressure, the two-region approach with a modified two-fluid model will be the theoretical basis of the new program to analyze the nuclear steam supply system during plant outages. To verify the analytical model in the first step, posttest calculations against the closed integral midloop experiments with loss of RHR were performed. The excellent simulation capacity of the ROSE code against the Institute of Nuclear Energy Research Integral System Test Facility (IIST) test data is demonstrated.« less

Quantitative Analysis of Land Loss in Coastal Louisiana Using Remote Sensing

NASA Astrophysics Data System (ADS)

Wales, P. M.; Kuszmaul, J.; Roberts, C.

2005-12-01

For the past thirty-five years the land loss along the Louisiana Coast has been recognized as a growing problem. One of the clearest indicators of this land loss is that in 2000 smooth cord grass (spartina alterniflora) was turning brown well before its normal hibernation period. Over 100,000 acres of marsh were affected by the 2000 browning. In 2001 data were collected using low altitude helicopter based transects of the coast, with 7,400 data points being collected by researchers at the USGS, National Wetlands Research Center, and Louisiana Department of Natural Resources. The surveys contained data describing the characteristics of the marsh, including latitude, longitude, marsh condition, marsh color, percent vegetated, and marsh die-back. Creating a model that combines remote sensing images, field data, and statistical analysis to develop a methodology for estimating the margin of error in measurements of coastal land loss (erosion) is the ultimate goal of the study. A model was successfully created using a series of band combinations (used as predictive variables). The most successful band combinations or predictive variables were the braud value [(Sum Visible TM Bands - Sum Infrared TM Bands)/(Sum Visible TM Bands + Sum Infrared TM Bands)], TM band 7/ TM band 2, brightness, NDVI, wetness, vegetation index, and a 7x7 autocovariate nearest neighbor floating window. The model values were used to generate the logistic regression model. A new image was created based on the logistic regression probability equation where each pixel represents the probability of finding water or non-water at that location in each image. Pixels within each image that have a high probability of representing water have a value close to 1 and pixels with a low probability of representing water have a value close to 0. A logistic regression model is proposed that uses seven independent variables. This model yields an accurate classification in 86.5% of the locations considered in the

Heat transfer analysis of underground U-type heat exchanger of ground source heat pump system.

PubMed

Pei, Guihong; Zhang, Liyin

2016-01-01

Ground source heat pumps is a building energy conservation technique. The underground buried pipe heat exchanging system of a ground source heat pump (GSHP) is the basis for the normal operation of an entire heat pump system. Computational-fluid-dynamics (CFD) numerical simulation software, ANSYS-FLUENT17.0 have been performed the calculations under the working conditions of a continuous and intermittent operation over 7 days on a GSHP with a single-well, single-U and double-U heat exchanger and the impact of single-U and double-U buried heat pipes on the surrounding rock-soil temperature field and the impact of intermittent operation and continuous operation on the outlet water temperature. The influence on the rock-soil temperature is approximately 13 % higher for the double-U heat exchanger than that of the single-U heat exchanger. The extracted energy of the intermittent operation is 36.44 kw·h higher than that of the continuous mode, although the running time is lower than that of continuous mode, over the course of 7 days. The thermal interference loss and quantity of heat exchanged for unit well depths at steady-state condition of 2.5 De, 3 De, 4 De, 4.5 De, 5 De, 5.5 De and 6 De of sidetube spacing are detailed in this work. The simulation results of seven working conditions are compared. It is recommended that the side-tube spacing of double-U underground pipes shall be greater than or equal to five times of outer diameter (borehole diameter: 180 mm).

Decay Heat Removal from a GFR Core by Natural Convection

DOE Office of Scientific and Technical Information (OSTI.GOV)

Williams, Wesley C.; Hejzlar, Pavel; Driscoll, Michael J.

2004-07-01

One of the primary challenges for Gas-cooled Fast Reactors (GFR) is decay heat removal after a loss of coolant accident (LOCA). Due to the fact that thermal gas cooled reactors currently under design rely on passive mechanisms to dissipate decay heat, there is a strong motivation to accomplish GFR core cooling through natural phenomena. This work investigates the potential of post-LOCA decay heat removal from a GFR core to a heat sink using an external convection loop. A model was developed in the form of the LOCA-COLA (Loss of Coolant Accident - Convection Loop Analysis) computer code as a meansmore » for 1D steady state convective heat transfer loop analysis. The results show that decay heat removal by means of gas cooled natural circulation is feasible under elevated post-LOCA containment pressure conditions. (authors)« less

Heat Transfer Model for Hot Air Balloons

NASA Astrophysics Data System (ADS)

Llado-Gambin, Adriana

A heat transfer model and analysis for hot air balloons is presented in this work, backed with a flow simulation using SolidWorks. The objective is to understand the major heat losses in the balloon and to identify the parameters that affect most its flight performance. Results show that more than 70% of the heat losses are due to the emitted radiation from the balloon envelope and that convection losses represent around 20% of the total. A simulated heating source is also included in the modeling based on typical thermal input from a balloon propane burner. The burner duty cycle to keep a constant altitude can vary from 10% to 28% depending on the atmospheric conditions, and the ambient temperature is the parameter that most affects the total thermal input needed. The simulation and analysis also predict that the gas temperature inside the balloon decreases at a rate of -0.25 K/s when there is no burner activity, and it increases at a rate of +1 K/s when the balloon pilot operates the burner. The results were compared to actual flight data and they show very good agreement indicating that the major physical processes responsible for balloon performance aloft are accurately captured in the simulation.

Tidal heating and mass loss in neutron star binaries - Implications for gamma-ray burst models

NASA Technical Reports Server (NTRS)

Meszaros, P.; Rees, M. J.

1992-01-01

A neutron star in a close binary orbit around another neutron star (or stellar-mass black hole) spirals inward owing to gravitational radiation. We discuss the effects of tidal dissipation during this process. Tidal energy dissipated in the neutron star's core escapes mainly as neutrinos, but heating of the crust, and outward diffusion of photons, blows off the outer layers of the star. This photon-driven mass loss precedes the final coalescence. The presence of this eject material impedes the escape of gamma-rays created via neutrino interactions. If an e(+) - e(-) fireball, created in the late stages of coalescence, were loaded with (or surrounded by) material with the mean column density of the ejecta, it could not be an efficient source of gamma-rays. Models for cosmologically distant gamma-rays burst that involve neutron stars must therefore be anisotropic, so that the fireball expands preferentially in directions where the column density of previously blown-off material is far below the spherically averaged value which we have calculated. Some possible 'scenarios' along these lines are briefly discussed.

Frictional strength and heat flow of southern San Andreas Fault

NASA Astrophysics Data System (ADS)

Zhu, P. P.

2016-01-01

Frictional strength and heat flow of faults are two related subjects in geophysics and seismology. To date, the investigation on regional frictional strength and heat flow still stays at the stage of qualitative estimation. This paper is concentrated on the regional frictional strength and heat flow of the southern San Andreas Fault (SAF). Based on the in situ borehole measured stress data, using the method of 3D dynamic faulting analysis, we quantitatively determine the regional normal stress, shear stress, and friction coefficient at various seismogenic depths. These new data indicate that the southern SAF is a weak fault within the depth of 15 km. As depth increases, all the regional normal and shear stresses and friction coefficient increase. The former two increase faster than the latter. Regional shear stress increment per kilometer equals 5.75 ± 0.05 MPa/km for depth ≤15 km; regional normal stress increment per kilometer is equal to 25.3 ± 0.1 MPa/km for depth ≤15 km. As depth increases, regional friction coefficient increment per kilometer decreases rapidly from 0.08 to 0.01/km at depths less than ~3 km. As depth increases from ~3 to ~5 km, it is 0.01/km and then from ~5 to 15 km, and it is 0.002/km. Previously, frictional strength could be qualitatively determined by heat flow measurements. It is difficult to obtain the quantitative heat flow data for the SAF because the measured heat flow data exhibit large scatter. However, our quantitative results of frictional strength can be employed to investigate the heat flow in the southern SAF. We use a physical quantity P f to describe heat flow. It represents the dissipative friction heat power per unit area generated by the relative motion of two tectonic plates accommodated by off-fault deformation. P f is called "fault friction heat." On the basis of our determined frictional strength data, utilizing the method of 3D dynamic faulting analysis, we quantitatively determine the regional long-term fault

Heat flow in relation to hydrothermal activity in the southern Black Rock Desert, Nevada

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sass, J.H.; Zoback, M.L.; Galanis, S.P. Jr.

1979-01-01

As part of an investigation of the Gerlach NE KGRA (Known Geothermal Resource Area) a number of heat-flow measurements were made in playa sediments of the southern Black Rock Desert, northwestern Nevada. These data together with additional previously unpublished heat-flow values reveal a complex pattern of heat flow with values ranging between 1.0 to 5.0 HFU (40 to 100 mWm/sup -2/) outside of the hot springs area. The mean heat flow for the 13 reported sites in the southern Black Rock Desert is 1.8 +- 0.15 HFU (75 +- 6 mWm/sup -2/). The complexity of the pattern of heat flowmore » is believed to arise from hydrothermal circulation supporting the numerous hot springs throughout the region. The fact that the lowest observed heat flow occurs in the deepest part of the basin strongly suggests that fluid movement within the basin represents part of the recharge for the hydrothermal system. A thermal balance for the system incorporating both anomalous conductive heat loss and convective heat loss from the spring systems indicate a total energy loss of about 8.0 Mcal/sec or 34 megawatts over an estimated 1000 km/sup 2/ region. Consideration of this additional heat loss yields a mean regional heat flow of 2.5 + HFU (100 + mWm/sup -2/) and warrants inclusion of this region in the Battle Mountain heat-flow high (Lachenbruch and Sass, 1977, 1978).« less

Identifying Return-Current Losses in Flare Hard X-ray Spectra

NASA Technical Reports Server (NTRS)

Holman, Gordon D.

2011-01-01

I will report on theoretical studies and a data analysis program aimed at identifying and physically interpreting breaks in hard X-ray spectra resulting from return-current energy losses, as well as heating of the flare plasma resulting from these losses.

Heat pipes in solar collectors

NASA Astrophysics Data System (ADS)

Bairamov, R.; Toiliev, K.

The diode property of heat pipes is evaluated for use in solar collectors. Model experiments show that the effect of heat pipes in solar collectors is most pronounced during the nighttime, when solar radiation is zero, due to a significant reduction in the heat loss from the transparent cover surface of the collector compared to that for conventional collectors. For a solar collector with a glass cover area of one square meter during the summer season when the maximum water temperature is 60 C and the discharge is 85 l/sq m/day, the water temperature in the accumulator tank of the solar collector with a heat pipe is 10-11 C higher than in the solar collector lacking a heat pipe. In addition, the design of a solar house with passive systems in which heat pipes serve as the heat eliminating mechanism is discussed

Comparison of feed energy costs of maintenance, lean deposition, and fat deposition in three lines of mice selected for heat loss.

PubMed

Eggert, D L; Nielsen, M K

2006-02-01

Three replications of mouse selection populations for high heat loss (MH), low heat loss (ML), and a nonselected control (MC) were used to estimate the feed energy costs of maintenance and gain and to test whether selection had changed these costs. At 21 and 49 d of age, mice were weighed and subjected to dual x-ray densitometry measurement for prediction of body composition. At 21 d, mice were randomly assigned to an ad libitum, an 80% of ad libitum, or a 60% of ad libitum feeding group for 28-d collection of individual feed intake. Data were analyzed using 3 approaches. The first approach was an attempt to partition energy intake between costs for maintenance, fat deposition, and lean deposition for each replicate, sex, and line by multiple regression of feed intake on the sum of daily metabolic weight (kg(0.75)), fat gain, and lean gain. Approach II was a less restrictive attempt to partition energy intake between costs for maintenance and total gain for each replicate, sex, and line by multiple regression of feed intake on the sum of daily metabolic weight and total gain. Approach III used multiple regression on the entire data set with pooled regressions on fat and lean gains, and subclass regressions for maintenance. Contrasts were conducted to test the effect of selection (MH - ML) and asymmetry of selection [(MH + ML)/2 - MC] for the various energy costs. In approach I, there were no differences between lines for costs of maintenance, fat deposition, or protein deposition, but we question our ability to estimate these accurately. In approach II, selection changed both cost of maintenance (P = 0.03) and gain (P = 0.05); MH mice had greater per unit costs than ML mice for both. Asymmetry of the selection response was found in approach II for the cost of maintenance (P = 0.06). In approach III, the effect of selection (P < 0.01) contributed to differences in the maintenance cost, but asymmetry of selection (P > 0.17) was not evident. Sex effects were found for

Atmosphere Expansion and Mass Loss of Close-orbit Giant Exoplanets Heated by Stellar XUV. I. Modeling of Hydrodynamic Escape of Upper Atmospheric Material

NASA Astrophysics Data System (ADS)

Shaikhislamov, I. F.; Khodachenko, M. L.; Sasunov, Yu. L.; Lammer, H.; Kislyakova, K. G.; Erkaev, N. V.

2014-11-01

In the present series of papers we propose a consistent description of the mass loss process. To study in a comprehensive way the effects of the intrinsic magnetic field of a close-orbit giant exoplanet (a so-called hot Jupiter) on atmospheric material escape and the formation of a planetary inner magnetosphere, we start with a hydrodynamic model of an upper atmosphere expansion in this paper. While considering a simple hydrogen atmosphere model, we focus on the self-consistent inclusion of the effects of radiative heating and ionization of the atmospheric gas with its consequent expansion in the outer space. Primary attention is paid to an investigation of the role of the specific conditions at the inner and outer boundaries of the simulation domain, under which different regimes of material escape (free and restricted flow) are formed. A comparative study is performed of different processes, such as X-ray and ultraviolet (XUV) heating, material ionization and recombination, H_3^ + cooling, adiabatic and Lyα cooling, and Lyα reabsorption. We confirm the basic consistency of the outcomes of our modeling with the results of other hydrodynamic models of expanding planetary atmospheres. In particular, we determine that, under the typical conditions of an orbital distance of 0.05 AU around a Sun-type star, a hot Jupiter plasma envelope may reach maximum temperatures up to ~9000 K with a hydrodynamic escape speed of ~9 km s-1, resulting in mass loss rates of ~(4-7) · 1010 g s-1. In the range of the considered stellar-planetary parameters and XUV fluxes, that is close to the mass loss in the energy-limited case. The inclusion of planetary intrinsic magnetic fields in the model is a subject of the follow-up paper (Paper II).

Exercise-heat acclimation in young and older trained cyclists.

PubMed

Best, Stuart; Thompson, Martin; Caillaud, Corinne; Holvik, Liv; Fatseas, George; Tammam, Amr

2014-11-01

The purpose of this study was to investigate the effect of age on the capacity to acclimatise to exercise-heat stress. This study hypothesised that age would not affect body temperature and heat loss effector responses to short-term exercise-heat acclimation in trained subjects. Seven young subjects (19-32 years) were matched with 7 older subjects (50-63 years). Subjects were highly trained but not specifically heat acclimated when they exercised for 60 min at 70%VO2max in hot-dry (35 °C, 40%RH) and thermoneutral (20 °C, 40%RH) conditions, pre and post 6 days of exercise-heat acclimation (70%VO2max, 35 °C, 40%RH). Rectal temperature (Tr), skin temperature (Tsk), heart rate (HR), cutaneous vascular conductance (CVC) and whole body sweat loss (Msw) were measured during each testing session and Tr and HR were measured during each acclimation session. Tr, Tsk, %HRmax, CVC and Msw were similar across age groups both pre and post heat acclimation. Following heat acclimation relative decreases and increases in Tr and Msw, respectively, were similar in both subject groups. There was a significant reduction in heart rate (%HRmax) and increase in final CVC following the acclimation programme in the young group (all p < 0.05) but not the older group. When comparing young and older well trained adults we found age affected the cardiovascular adaptation but not body temperature or whole body sweat loss to exercise-heat acclimation. These data suggest age does not affect the capacity to acclimatise to exercise-heat stress in highly trained adults undergoing short-term heat acclimation. Copyright © 2013 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

Two-dimensional heat flow apparatus

NASA Astrophysics Data System (ADS)

McDougall, Patrick; Ayars, Eric

2014-06-01

We have created an apparatus to quantitatively measure two-dimensional heat flow in a metal plate using a grid of temperature sensors read by a microcontroller. Real-time temperature data are collected from the microcontroller by a computer for comparison with a computational model of the heat equation. The microcontroller-based sensor array allows previously unavailable levels of precision at very low cost, and the combination of measurement and modeling makes for an excellent apparatus for the advanced undergraduate laboratory course.

The Path for the Development and Release of Heat Tolerant Soybean Lines

USDA-ARS?s Scientific Manuscript database

High ambient temperatures can damage soybean seed. Heat is recognized by the crop insurance industry as a major cause for monetary losses to producers. The USDA Risk Management Agency reported payouts to soybean farmers of more than $247 million on over 1.62 million hectares for losses due to heat...

On designing low pressure loss working spaces for a planar Stirling micromachine

NASA Astrophysics Data System (ADS)

Hachey, M.-A.; Léveillé, É.; Fréchette, L. G.; Formosa, F.

2015-12-01

In this paper, research was undertaken with the objective to design low pressure loss working spaces for a Stirling cycle micro heat engine operating from low temperature waste heat. This planar free-piston heat engine is anticipated to operate at the kHz level with mm3 displacement. Given the resonant nature of the free-piston configuration, the complexity of its working gas’ flow geometry and its projected high operating frequency, flow analysis is relatively complex. Design considerations were thus based on fast prototyping and experimentation. Results show that geometrical features, such as a sharp 90° corner between the regenerator and working spaces, are strong contributors to pressure losses. This research culminated into a promising revised working space configuration for engine start-up, as it considerably reduced total pressure losses, more than 80% at Re = 700, from the original design.

Modeling Cyclic Phase Change and Energy Storage in Solar Heat Receivers

NASA Technical Reports Server (NTRS)

Hall, Carsie A., III; Glakpe, Emmanuel K.; Cannon, Joseph N.; Kerslake, Thomas W.

1997-01-01

Numerical results pertaining to cyclic melting and freezing of an encapsulated phase change material (PCM), integrated into a solar heat receiver, have been reported. The cyclic nature of the present melt/freeze problem is relevant to latent heat thermal energy storage (LHTES) systems used to power solar Brayton engines in microgravity environments. Specifically, a physical and numerical model of the solar heat receiver component of NASA Lewis Research Center's Ground Test Demonstration (GTD) project was developed and results compared with available experimental data. Multi-conjugate effects such as the convective fluid flow of a low-Prandtl-number fluid, coupled with thermal conduction in the phase change material, containment tube and working fluid conduit were accounted for in the model. A single-band thermal radiation model was also included to quantify reradiative energy exchange inside the receiver and losses through the aperture. The eutectic LiF-CaF2 was used as the phase change material (PCM) and a mixture of He/Xe was used as the working fluid coolant. A modified version of the computer code HOTTube was used to generate results for comparisons with GTD data for both the subcooled and two-phase regimes. While qualitative trends were in close agreement for the balanced orbit modes, excellent quantitative agreement was observed for steady-state modes.

TEWI Evaluation for Refrigeration and Air-Conditioning Systems in Office Buildings with Different Regional Heat Demand

NASA Astrophysics Data System (ADS)

Sobue, Atsushi; Watanabe, Koichi

In the present study, we quantitatively evaluated the global warming impact by refrigeration and air-conditioning systems in office buildings on the basis of reliable TEWI information. This paper proposes an improved TEWI evaluation procedure by considering regional heat demands and part load of air-conditioning systems. In the TEWI evaluation of commercial chillers, a percentage of the impact by refrigerant released to the atmosphere (direct effect) is less than 19.9% in TEWI values. Therefore, a reduction of the impact by CO2 released as a result of the energy consumed to drive the refrigeration or air-conditioning systems through out their lifetime (indirect effect) is the most effective measure in reducing the global warming impact. On the other hand, we have also pointed out energy loss that might be generated by an excess investment to the equipment. We have also showed a usefulness in dividing the heating / cooling system into several small-capacity units so as to improve the energy utilization efficiency.

The Effects of Heat Adaptation on Physiology, Perception and Exercise Performance in the Heat: A Meta-Analysis.

PubMed

Tyler, Christopher J; Reeve, Tom; Hodges, Gary J; Cheung, Stephen S

2016-11-01

Exercise performance and capacity are impaired in hot, compared to temperate, conditions. Heat adaptation (HA) is one intervention commonly adopted to reduce this impairment because it may induce beneficial exercise performance and physiological and perceptual adaptations. A number of investigations have been conducted on HA but, due to large methodological differences, the effectiveness of different HA regimens remain unclear. (1) To quantify the effect of different HA regimens on exercise performance and the physiological and perceptual responses to subsequent heat exposure. (2) To offer practical HA recommendations and suggestions for future HA research based upon a systematic and quantitative synthesis of the literature. PubMed was searched for original research articles published up to, and including, 16 February 2016 using appropriate first- and second-order search terms. English-language, peer-reviewed, full-text original articles using human participants were reviewed using the four-stage process identified in the PRISMA statement. Data for the following variables were obtained from the manuscripts by at least two of the authors: participant sex, maximal oxygen consumption and age; HA duration, frequency, modality, temperature and humidity; exercise performance and capacity; core and skin temperature; heart rate, stroke volume, cardiac output, skin blood flow, sweat onset temperature, body mass loss, sweat rate, perception of thirst, volitional fluid consumption, plasma volume changes; sweat concentrations of sodium, chloride and potassium; aldosterone, arginine vasopressin, heat shock proteins (Hsp), ratings of perceived exertion (RPE) and thermal sensation. Data were divided into three groups based upon the frequency of the HA regimen. Performance and capacity data were also divided into groups based upon the type of HA used. Hedges' g effect sizes and 95 % confidence intervals were calculated. Correlations were run where appropriate. Ninety-six articles

NOy production, ozone loss and changes in net radiative heating due to energetic particle precipitation in 2002-2010

NASA Astrophysics Data System (ADS)

Sinnhuber, Miriam; Berger, Uwe; Funke, Bernd; Nieder, Holger; Reddmann, Thomas; Stiller, Gabriele; Versick, Stefan; von Clarmann, Thomas; Maik Wissing, Jan

2018-01-01

winter, ranging from 10-50 % during solar maximum to 2-10 % during solar minimum. Ozone loss continues throughout polar summer after strong solar proton events in the Southern Hemisphere and after large sudden stratospheric warmings in the Northern Hemisphere. During mid-winter, the ozone loss causes a reduction of the infrared radiative cooling, i.e., a positive change of the net radiative heating (effective warming), in agreement with analyses of geomagnetic forcing in stratospheric temperatures which show a warming in the late winter upper stratosphere. In late winter and spring, the sign of the net radiative heating change turns to negative (effective cooling). This spring-time cooling lasts well into summer and continues until the following autumn after large solar proton events in the Southern Hemisphere, and after sudden stratospheric warmings in the Northern Hemisphere.

Determining heat loss from the surface of polymer films via modeling of experimental fluorescence thermometry

NASA Astrophysics Data System (ADS)

Firestone, Gabriel; Bochinski, Jason; Meth, Jeffrey; Clarke, Laura

Understanding of the heat transfer characteristics of a polymer during processing is critical to predicting and controlling the resulting properties and has been studied extensively in injection molding. As new methodologies for polymer processing are developed, such as photothermal heating, it is important to build an understanding of how heat transfer properties change under these novel conditions. By combining theoretical and experimental approaches, the thermal properties of photothermally heated polymer films were measured. The key idea is that by measuring the steady state temperature profile of a spot heated polymer film via a fluorescence probe (the temperature versus distance from the heated region) and fitting to a theoretical model, heat transfer coefficients can be extracted. We apply this approach to three different polymer systems, crosslinked epoxy, poly(methyl methacrylate) and poly(ethylene oxide) thin films with a range of thicknesses, under different heating laser intensities and with different resultant temperatures. We will discuss the resultant trends and extension of the model beyond a simple spot heating configuration. Support from National Science Foundation CMMI-1069108 and CMMI-1462966.

Kinetic analysis of cooking losses from beef and other animal muscles heated in a water bath--effect of sample dimensions and prior freezing and ageing.

PubMed

Oillic, Samuel; Lemoine, Eric; Gros, Jean-Bernard; Kondjoyan, Alain

2011-07-01

Cooking loss kinetics were measured on cubes and parallelepipeds of beef Semimembranosus muscle ranging from 1 cm × 1 cm × 1 cm to 7 cm × 7 cm × 28 cm in size. The samples were water bath-heated at three different temperatures, i.e. 50°C, 70°C and 90°C, and for five different times. Temperatures were simulated to help interpret the results. Pre-freezing the sample, difference in ageing time, and in muscle fiber orientation had little influence on cooking losses. At longer treatment times, the effects of sample size disappeared and cooking losses depended only on the temperature. A selection of the tests was repeated on four other beef muscles and on veal, horse and lamb Semimembranosus muscle. Kinetics followed similar curves in all cases but resulted in different final water contents. The shape of the kinetics curves suggests first-order kinetics. Copyright © 2011 The American Meat Science Association. Published by Elsevier Ltd. All rights reserved.

Evaluation of Reference Genes for Normalization of Gene Expression Using Quantitative RT-PCR under Aluminum, Cadmium, and Heat Stresses in Soybean.

PubMed

Gao, Mengmeng; Liu, Yaping; Ma, Xiao; Shuai, Qin; Gai, Junyi; Li, Yan

2017-01-01

Quantitative reverse transcription polymerase chain reaction (qRT-PCR) is widely used to analyze the relative gene expression level, however, the accuracy of qRT-PCR is greatly affected by the stability of reference genes, which is tissue- and environment- dependent. Therefore, choosing the most stable reference gene in a specific tissue and environment is critical to interpret gene expression patterns. Aluminum (Al), cadmium (Cd), and heat stresses are three important abiotic factors limiting soybean (Glycine max) production in southern China. To identify the suitable reference genes for normalizing the expression levels of target genes by qRT-PCR in soybean response to Al, Cd and heat stresses, we studied the expression stability of ten commonly used housekeeping genes in soybean roots and leaves under these three abiotic stresses, using five approaches, BestKeeper, Delta Ct, geNorm, NormFinder and RefFinder. We found TUA4 is the most stable reference gene in soybean root tips under Al stress. Under Cd stress, Fbox and UKN2 are the most stable reference genes in roots and leaves, respectively, while 60S is the most suitable reference gene when analyzing both roots and leaves together. For heat stress, TUA4 and UKN2 are the most stable housekeeping genes in roots and leaves, respectively, and UKN2 is the best reference gene for analysis of roots and leaves together. To validate the reference genes, we quantified the relative expression levels of six target genes that were involved in soybean response to Al, Cd or heat stresses, respectively. The expression patterns of these target genes differed between using the most and least stable reference genes, suggesting the selection of a suitable reference gene is critical for gene expression studies.

Modelling of Heat and Moisture Loss Through NBC Ensembles

DTIC Science & Technology

1991-11-01

the heat and moisture transport through various NBC clothing ensembles. The analysis involves simplifying the three dimensional physical problem of... clothing on a person to that of a one dimensional problem of flow through parallel layers of clothing and air. Body temperatures are calculated based on...prescribed work rates, ambient conditions and clothing properties. Sweat response and respiration rates are estimated based on empirical data to

Structural and heat-flow implications of infrared anomalies at Mt. Hood, Oregon

USGS Publications Warehouse

Friedman, Jules D.; Frank, David

1977-01-01

Surface thermal features occur in an area of 9700 m2 at Mt. Hood, on the basis of an aerial line-scan survey made April 26, 1973. The distribution of the thermal areas below the summit of Mt. Hood, shown on planimetrically corrected maps at 1:12,000, suggests structural control by a fracture system and brecciated zone peripheral to a hornblende-dacite plug dome (Crater Rock), and by a concentric fracture system that may have been associated with development of the present crater. The extent and inferred temperature of the thermal areas permits a preliminary estimate of a heat discharge of 10 megawatts, by analogy with similar fumarole and thermal fields of Mt. Baker, Washington. This figure includes a heat loss of 4 megawatts (MW) via conduction, diffusion, evaporation, and radiation to the atmosphere, and a somewhat less certain loss of 6MW via fumarolic mass transfer of vapor and advective heat loss from runoff and ice melt. The first part of the estimate is based on two-point models for differential radiant exitance and differential flux via conduction, diffusion, evaporation, and radiation from heat balance of the ground surface. Alternate methods for estimating volcanogenic geothermal flux that assume a quasi-steady state heat flow also yield estimates in the 5-11 MW range. Heat loss equivalent to cooling of the dacite plug dome is judged to be insufficient to account for the heat flux at the fumarole fields.

Numerical prediction of micro-channel LD heat sink operated with antifreeze based on CFD method

NASA Astrophysics Data System (ADS)

Liu, Gang; Liu, Yang; Wang, Chao; Wang, Wentao; Wang, Gang; Tang, Xiaojun

2014-12-01

To theoretically study the feasibility of antifreeze coolants applied as cooling fluids for high power LD heat sink, detailed Computational Fluid Dynamics (CFD) analysis of liquid cooled micro-channels heat sinks is presented. The performance operated with antifreeze coolant (ethylene glycol aqueous solution) compared with pure water are numerical calculated for the heat sinks with the same micro-channels structures. The maximum thermal resistance, total pressure loss (flow resistance), thermal resistance vs. flow-rate, and pressure loss vs. flow-rate etc. characteristics are numerical calculated. The results indicate that the type and temperature of coolants plays an important role on the performance of heat sinks. The whole thermal resistance and pressure loss of heat sinks increase significantly with antifreeze coolants compared with pure water mainly due to its relatively lower thermal conductivity and higher fluid viscosity. The thermal resistance and pressure loss are functions of the flow rate and operation temperature. Increasing of the coolant flow rate can reduce the thermal resistance of heat sinks; meanwhile increase the pressure loss significantly. The thermal resistance tends to a limit with increasing flow rate, while the pressure loss tends to increase exponentially with increasing flow rate. Low operation temperature chiefly increases the pressure loss rather than thermal resistance due to the remarkable increasing of fluid viscosity. The actual working point of the cooling circulation system can be determined on the basis of the pressure drop vs. flow rate curve for the micro-channel heat sink and that for the circulation system. In the same system, if the type or/and temperature of the coolant is changed, the working point is accordingly influenced, that is, working flow rate and pressure is changed simultaneously, due to which the heat sink performance is influenced. According to the numerical simulation results, if ethylene glycol aqueous

Three insulation methods to minimize intravenous fluid administration set heat loss.

PubMed

Piek, Richardt; Stein, Christopher

2013-01-01

To assess the effect of three methods for insulating an intravenous (IV) fluid administration set on the temperature of warmed fluid delivered rapidly in a cold environment. The three chosen techniques for insulation of the IV fluid administration set involved enclosing the tubing of the set in 1) a cotton conforming bandage, 2) a reflective emergency blanket, and 3) a combination of technique 2 followed by technique 1. Intravenous fluid warmed to 44°C was infused through a 20-drop/mL 180-cm-long fluid administration set in a controlled environmental temperature of 5°C. Temperatures in the IV fluid bag, the distal end of the fluid administration set, and the environment were continuously measured with resistance thermosensors. Twenty repetitions were performed in four conditions, namely, a control condition (with no insulation) and the three different insulation methods described above. One-way analysis of variance was used to assess the mean difference in temperature between the IV fluid bag and the distal fluid administration set under the four conditions. In the control condition, a mean of 5.28°C was lost between the IV fluid bag and the distal end of the fluid administration set. There was a significant difference found between the four conditions (p < 0.001). A mean of 3.53°C was lost between the IV fluid bag and the distal end of the fluid administration set for both the bandage and reflective emergency blanket, and a mean of 3.06°C was lost when the two methods were combined. Using inexpensive and readily available materials to insulate a fluid administration set can result in a reduction of heat loss in rapidly infused, warmed IV fluid in a cold environment.

Program documentation: Surface heating rate of thin skin models (THNSKN)

NASA Technical Reports Server (NTRS)

Mcbryde, J. D.

1975-01-01

Program THNSKN computes the mean heating rate at a maximum of 100 locations on the surface of thin skin transient heating rate models. Output is printed in tabular form and consists of time history tabulation of temperatures, average temperatures, heat loss without conduction correction, mean heating rate, least squares heating rate, and the percent standard error of the least squares heating rates. The input tape used is produced by the program EHTS03.

Heat loss and hypothermia in free diving: Estimation of survival time under water

NASA Astrophysics Data System (ADS)

Aguilella-Arzo, Marcel; Alcaraz, Antonio; Aguilella, Vicente M.

2003-04-01

The heat exchange between a diver and the colder surrounding water is analyzed on the basis of the fundamental equations of thermal transport. To estimate the decrease in the diver's body temperature as a function of time, we discuss the complex interplay of several factors including the body heat production rate, the role of the diver's wet suit, and the way different heat exchange mechanisms (conduction, convection, and radiation) contribute to thermal transport. This knowledge could be useful to prevent physiological disorders that occur when the human body temperature drops below 35 °C.

A pan-European quantitative assessment of soil loss by wind

NASA Astrophysics Data System (ADS)

Borrelli, Pasqualle; Lugato, Emanuele; Panagos, Panos

2016-04-01

Soil erosion by wind is a serious environmental problem often low perceived but resulting in severe soil degradation forms. On the long-term a considerable part of topsoil - rich in nutrient and organic matters - could be removed compromising the agricultural productivity and inducing an increased use of fertilizers. Field scale studies and observations proven that wind erosion is a serious problem in many European sites. The state-of-the-art suggests a scenario where wind erosion locally affects the temperate climate areas of the northern European countries, as well as the semi-arid areas of the Mediterranean region. However, observations, field measurements and modelling assessments are extremely limited and unequally distributed across Europe. It implies a lack of knowledge about where and when wind erosion occurs, limiting policy actions aimed at mitigating land degradation. To gain a better understanding about soil degradation process, the Soil Resource Assessment working group of the Joint Research Centre carried out the first pan-European assessments of wind-erodible fraction of soil (EF) (Geoderma, 232, 471-478, 2014) and land susceptibility to wind erosion (Land Degradation & Development, DOI: 10.1002/ldr.2318). Today's challenge is to integrate the insights archived by these pan-European assessments, local experiments and field-scale models into a new generation of regional-scale wind erosion models. A GIS version of the Revised Wind Erosion Equation (RWEQ) was developed with the aim to i) move a step forward into the aforementioned challenges, and ii) evaluate the soil loss potential due to wind erosion in the agricoltural land of the EU. The model scheme was designed to describe daily soil loss potential, combining spatiotemporal conditions of soil erodibility, crust factor, soil moisture content, vegetation coverage and wind erosivity at 1 km2 resolution. The average soil loss predicted by GIS-RWEQ in the EU arable land ranges from 0 to 39.9 Mg ha-1 yr

Effects of encapsulated niacin on evaporative heat loss and body temperature in moderately heat-stressed lactating Holstein cows.

PubMed

Zimbelman, R B; Baumgard, L H; Collier, R J

2010-06-01

Twelve multiparous Holstein cows (145+/-9 d in milk) were randomly assigned to receive either 0 g/d of encapsulated niacin (control diet; C) or 12 g/d of encapsulated niacin (NI) and were exposed to thermoneutral (TN; 7 d) or heat stress (HS; 7 d) conditions in climate-controlled chambers. The temperature-humidity index during TN conditions never exceeded 72, whereas HS conditions consisted of a circadian temperature range in which the temperature-humidity index exceeded 72 for 12 h/d. Measures of thermal status obtained 4 times/d included respiration rate (RR); rectal temperature; surface temperature of both shaved and unshaved areas at the rump, shoulder, and tail head; vaginal temperature; and evaporative heat loss (EVHL) of the shoulder shaved and unshaved areas. Cows fed NI had increased free plasma niacin concentrations in both the TN and HS periods (1.70 vs. 1.47+/-0.17 microg/mL). Milk yield did not differ between dietary groups or periods. Dry matter intake was not affected by NI, but decreased (3%) for both C and NI treatments during HS. Water intake was increased during HS in both treatments (C: 40.4 vs. 57.7+/-0.8L/d for TN and HS, respectively; NI: 52.7 vs. 57.7+/-0.8 L/d for TN and HS, respectively). Average EVHL for shaved and unshaved skin for C and NI treatments was higher during HS (90.1 vs. 108.1 g/m(2) per hour) than TN (20.7 vs. 15.7+/-4.9 g/m(2) per hour). Between 1000 and 1600 h, mean EVHL for shaved and unshaved areas for NI fed cows was higher than for C fed cows (106.9 vs. 94.4+/-4.9 g/m(2) per hour). The NI fed cows had decreased rectal temperatures during HS compared with the C fed cows (38.17 vs. 38.34+/-0.07 degrees C) and had lower vaginal temperatures (38.0 vs. 38.4+/-0.02 degrees C). Calculated metabolic rate decreased during HS regardless of diet (50.25 and 49.70+/-0.48 kcal/kg of body weight per day for TN and HS, respectively). Feeding NI increased free plasma NI levels, increased EVHL during peak thermal load, and was associated

Do older adults experience greater thermal strain during heat waves?

PubMed

Stapleton, Jill M; Larose, Joanie; Simpson, Christina; Flouris, Andreas D; Sigal, Ronald J; Kenny, Glen P

2014-03-01

Heat waves are the cause of many preventable deaths around the world, especially among older adults and in countries with more temperate climates. In the present study, we examined the effects of age on whole-body heat loss and heat storage during passive exposure to environmental conditions representative of the upper temperature extremes experienced in Canada. Direct and indirect calorimetry measured whole-body evaporative heat loss and dry heat exchange, as well as the change in body heat content. Twelve younger (21 ± 3 years) and 12 older (65 ± 5 years) adults with similar body weight (younger: 72.0 ± 4.4 kg; older: 80.1 ± 4.2 kg) and body surface area (younger: 1.8 ± 0.1 m(2); older: 2.0 ± 0.1 m(2)) rested for 2 h in a hot-dry [36.5 °C, 20% relative humidity (RH)] or hot-humid (36.5 °C, 60% RH) environment. In both conditions, evaporative heat loss was not significantly different between groups (dry: p = 0.758; humid: p = 0.814). However, the rate of dry heat gain was significantly greater (by approx. 10 W) for older adults relative to younger adults during the hot-dry (p = 0.032) and hot-humid exposure (p = 0.019). Consequently, the cumulative change in body heat content after 2 h of rest was significantly greater in older adults in the hot-dry (older: 212 ± 25 kJ; younger: 131 ± 27 kJ, p = 0.018) as well as the hot-humid condition (older: 426 ± 37 kJ; younger: 317 ± 45 kJ, p = 0.037). These findings demonstrate that older individuals store more heat during short exposures to dry and humid heat, suggesting that they may experience increased levels of thermal strain in such conditions than people of younger age.

Semitransparent ceramic heat-insulation of eco-friendly Low- Heat-Rejection diesel

NASA Astrophysics Data System (ADS)

Merzlikin, V. G.; Gutierrez, M. O.; Makarov, A. R.; Kostukov, A. V.; Dementev, A. A.; Khudyakov, S. V.; Zagumennov, F. A.

2018-03-01

Efficiency of diesel has been studied using well-known types of the ceramic heat-insulating HICs- or thermal barrier TBCs-coatings. This problem is relevant for a high-speed diesel combustion chamber in which an intensive radiant component (near IR) reaches ~50% within total thermal flux. Therefore, in their works the authors had been offering new concept of study these materials as semitransparent SHICs-, STBCs-coatings. On the Mie scattering theory, the effect of selection of the specific structural composition and porosity of coatings on the variation of their optical parameters is considered. Conducted spectrophotometric modeling of the volume-absorbed radiant energy by the coating had determined their acceptable temperature field. For rig testings, a coated piston using selected SHIC (PSZ-ceramic ZrO2+8%Y2O3) with a calculated optimum temperature gradient was chosen. A single cylinder experimental tractor diesel was used. At rotation frequency n > 2800 rpm, the heat losses were no more than 0.2 MW/m2. Executed testings showed ~2-3% lower specific fuel consumption in contrast to the diesel with an uncoated piston. Effective power and drive torque were ∼2-5% greater. The authors have substantiated the growth the efficiency of this Low-Heat-Rejection(LHR) diesel due to the known effect of soot deposition gasification at high speed. Then unpolluted semitransparent ceramic thermal insulation forms the required thermoradiation fields and temperature profiles and can affect regulation of heat losses and a reduction of primarily nitrogen dioxide generation.

Chemical heat pump

DOEpatents

Greiner, Leonard

1980-01-01

A chemical heat pump system is disclosed for use in heating and cooling structures such as residences or commercial buildings. The system is particularly adapted to utilizing solar energy, but also increases the efficiency of other forms of thermal energy when solar energy is not available. When solar energy is not available for relatively short periods of time, the heat storage capacity of the chemical heat pump is utilized to heat the structure as during nighttime hours. The design also permits home heating from solar energy when the sun is shining. The entire system may be conveniently rooftop located. In order to facilitate installation on existing structures, the absorber and vaporizer portions of the system may each be designed as flat, thin wall, thin pan vessels which materially increase the surface area available for heat transfer. In addition, this thin, flat configuration of the absorber and its thin walled (and therefore relatively flexible) construction permits substantial expansion and contraction of the absorber material during vaporization and absorption without generating voids which would interfere with heat transfer. The heat pump part of the system heats or cools a house or other structure through a combination of evaporation and absorption or, conversely, condensation and desorption, in a pair of containers. A set of automatic controls change the system for operation during winter and summer months and for daytime and nighttime operation to satisfactorily heat and cool a house during an entire year. The absorber chamber is subjected to solar heating during regeneration cycles and is covered by one or more layers of glass or other transparent material. Daytime home air used for heating the home is passed at appropriate flow rates between the absorber container and the first transparent cover layer in heat transfer relationship in a manner that greatly reduce eddies and resultant heat loss from the absorbant surface to ambient atmosphere.

Solar steam generation by heat localization.

PubMed

Ghasemi, Hadi; Ni, George; Marconnet, Amy Marie; Loomis, James; Yerci, Selcuk; Miljkovic, Nenad; Chen, Gang

2014-07-21

Currently, steam generation using solar energy is based on heating bulk liquid to high temperatures. This approach requires either costly high optical concentrations leading to heat loss by the hot bulk liquid and heated surfaces or vacuum. New solar receiver concepts such as porous volumetric receivers or nanofluids have been proposed to decrease these losses. Here we report development of an approach and corresponding material structure for solar steam generation while maintaining low optical concentration and keeping the bulk liquid at low temperature with no vacuum. We achieve solar thermal efficiency up to 85% at only 10 kW m(-2). This high performance results from four structure characteristics: absorbing in the solar spectrum, thermally insulating, hydrophilic and interconnected pores. The structure concentrates thermal energy and fluid flow where needed for phase change and minimizes dissipated energy. This new structure provides a novel approach to harvesting solar energy for a broad range of phase-change applications.

Weight loss and bone mineral density.

PubMed

Hunter, Gary R; Plaisance, Eric P; Fisher, Gordon

2014-10-01

Despite evidence that energy deficit produces multiple physiological and metabolic benefits, clinicians are often reluctant to prescribe weight loss in older individuals or those with low bone mineral density (BMD), fearing BMD will be decreased. Confusion exists concerning the effects that weight loss has on bone health. Bone density is more closely associated with lean mass than total body mass and fat mass. Although rapid or large weight loss is often associated with loss of bone density, slower or smaller weight loss is much less apt to adversely affect BMD, especially when it is accompanied with high intensity resistance and/or impact loading training. Maintenance of calcium and vitamin D intake seems to positively affect BMD during weight loss. Although dual energy X-ray absorptiometry is normally used to evaluate bone density, it may overestimate BMD loss following massive weight loss. Volumetric quantitative computed tomography may be more accurate for tracking bone density changes following large weight loss. Moderate weight loss does not necessarily compromise bone health, especially when exercise training is involved. Training strategies that include heavy resistance training and high impact loading that occur with jump training may be especially productive in maintaining, or even increasing bone density with weight loss.

Effects of rotation on coolant passage heat transfer. Volume 1: Coolant passages with smooth walls

NASA Technical Reports Server (NTRS)

Hajek, T. J.; Wagner, J. H.; Johnson, B. V.; Higgins, A. W.; Steuber, G. D.

1991-01-01

An experimental program was conducted to investigate heat transfer and pressure loss characteristics of rotating multipass passages, for configurations and dimensions typical of modern turbine blades. The immediate objective was the generation of a data base of heat transfer and pressure loss data required to develop heat transfer correlations and to assess computational fluid dynamic techniques for rotating coolant passages. Experiments were conducted in a smooth wall large scale heat transfer model.

Sauropod necks: are they really for heat loss?

PubMed

Henderson, Donald M

2013-01-01

Three-dimensional digital models of 16 different sauropods were used to examine the scaling relationship between metabolism and surface areas of the whole body, the neck, and the tail in an attempt to see if the necks could have functioned as radiators for the elimination of excess body heat. The sauropod taxa sample ranged in body mass from a 639 kg juvenile Camarasaurus to a 25 t adult Brachiosaurus. Metabolism was assumed to be directly proportional to body mass raised to the ¾ power, and estimates of body mass accounted for the presence of lungs and systems of air sacs in the trunk and neck. Surface areas were determined by decomposing the model surfaces into triangles and their areas being computed by vector methods. It was found that total body surface area was almost isometric with body mass, and that it showed negative allometry when plotted against metabolic rate. In contrast, neck area showed positive allometry when plotted against metabolic rate. Tail area show negative allometry with respect to metabolic rate. The many uncertainties about the biology of sauropods, and the variety of environmental conditions that different species experienced during the groups 150 million years of existence, make it difficult to be absolutely certain about the function of the neck as a radiator. However, the functional combination of the allometric increase of neck area, the systems of air sacs in the neck and trunk, the active control of blood flow between the core and surface of the body, changing skin color, and strategic orientation of the neck with respect to wind, make it plausible that the neck could have functioned as a radiator to avoid over-heating.

Sauropod Necks: Are They Really for Heat Loss?

PubMed Central

Henderson, Donald M.

2013-01-01

Three-dimensional digital models of 16 different sauropods were used to examine the scaling relationship between metabolism and surface areas of the whole body, the neck, and the tail in an attempt to see if the necks could have functioned as radiators for the elimination of excess body heat. The sauropod taxa sample ranged in body mass from a 639 kg juvenile Camarasaurus to a 25 t adult Brachiosaurus. Metabolism was assumed to be directly proportional to body mass raised to the ¾ power, and estimates of body mass accounted for the presence of lungs and systems of air sacs in the trunk and neck. Surface areas were determined by decomposing the model surfaces into triangles and their areas being computed by vector methods. It was found that total body surface area was almost isometric with body mass, and that it showed negative allometry when plotted against metabolic rate. In contrast, neck area showed positive allometry when plotted against metabolic rate. Tail area show negative allometry with respect to metabolic rate. The many uncertainties about the biology of sauropods, and the variety of environmental conditions that different species experienced during the groups 150 million years of existence, make it difficult to be absolutely certain about the function of the neck as a radiator. However, the functional combination of the allometric increase of neck area, the systems of air sacs in the neck and trunk, the active control of blood flow between the core and surface of the body, changing skin color, and strategic orientation of the neck with respect to wind, make it plausible that the neck could have functioned as a radiator to avoid over-heating. PMID:24204747

Change in algal symbiont communities after bleaching, not prior heat exposure, increases heat tolerance of reef corals.

PubMed

Silverstein, Rachel N; Cunning, Ross; Baker, Andrew C

2015-01-01

Mutualistic organisms can be particularly susceptible to climate change stress, as their survivorship is often limited by the most vulnerable partner. However, symbiotic plasticity can also help organisms in changing environments by expanding their realized niche space. Coral-algal (Symbiodinium spp.) symbiosis exemplifies this dichotomy: the partnership is highly susceptible to 'bleaching' (stress-induced symbiosis breakdown), but stress-tolerant symbionts can also sometimes mitigate bleaching. Here, we investigate the role of diverse and mutable symbiotic partnerships in increasing corals' ability to thrive in high temperature conditions. We conducted repeat bleaching and recovery experiments on the coral Montastraea cavernosa, and used quantitative PCR and chlorophyll fluorometry to assess the structure and function of Symbiodinium communities within coral hosts. During an initial heat exposure (32 °C for 10 days), corals hosting only stress-sensitive symbionts (Symbiodinium C3) bleached, but recovered (at either 24 °C or 29 °C) with predominantly (>90%) stress-tolerant symbionts (Symbiodinium D1a), which were not detected before bleaching (either due to absence or extreme low abundance). When a second heat stress (also 32 °C for 10 days) was applied 3 months later, corals that previously bleached and were now dominated by D1a Symbiodinium experienced less photodamage and symbiont loss compared to control corals that had not been previously bleached, and were therefore still dominated by Symbiodinium C3. Additional corals that were initially bleached without heat by a herbicide (DCMU, at 24 °C) also recovered predominantly with D1a symbionts, and similarly lost fewer symbionts during subsequent thermal stress. Increased thermotolerance was also not observed in C3-dominated corals that were acclimated for 3 months to warmer temperatures (29 °C) before heat stress. These findings indicate that increased thermotolerance post-bleaching resulted from

Vaporization characteristics of carbon heat shields under radiative heating.

NASA Technical Reports Server (NTRS)

Davy, W. C.; Bar-Nun, A.

1972-01-01

Study of the vaporization characteristics of samples of ATJ graphite, a material that has been considered for use on a Jovian probe. These samples were subjected to radiative heating loads of approximately 2 kW/sq cm in argon atmospheres of pressures from 0.00046 to 1 atm. Surface temperatures, mass loss rates, and spatially resolved emission spectral data were recorded. These data are analyzed to determine carbon vapor pressure as a function of temperature and are compared with current models for the vapor pressure of carbon. The effects of finite vaporization (i.e., nonequilibrium) rates are considered and compared with experiment. Estimates of the heat of vaporization from an energy balance are also presented.

Limits on modes of lithospheric heat transport on Venus from impact crater density

NASA Technical Reports Server (NTRS)

Grimm, Robert E.; Solomon, Sean C.

1987-01-01

Based on the observed density of impact craters on the Venus surface obtained from Venera 15-16 radar images, a formalism to estimate the upper bounds on the contributions made to lithospheric heat transport by volcanism and lithospheric recycling is presented. The Venera 15-16 data, if representative of the entire planet, limit the average rate of volcanic resurfacing on Venus to less than 2 cu km/yr (corresponding to less than 1 percent of the global heat loss), and limit the rate of lithospheric recycling to less than 1.5 sq km/yr (and probably to less than 0.5 sq km/yr), corresponding to 25 percent (and to 9 percent) of the global heat loss. The present results indicate that heat loss at lithospheric levels in Venus is dominated by conduction.

Superolateral Hoffa's fat pad (SHFP) oedema and patellar cartilage volume loss: quantitative analysis using longitudinal data from the Foundation for the National Institute of Health (FNIH) Osteoarthritis Biomarkers Consortium.

PubMed

Haj-Mirzaian, Arya; Guermazi, Ali; Hafezi-Nejad, Nima; Sereni, Christopher; Hakky, Michael; Hunter, David J; Zikria, Bashir; Roemer, Frank W; Demehri, Shadpour

2018-04-12

To determine the association of superolateral Hoffa's fat pad (SHFP) oedema and patellofemoral joint structural damage in participants of Foundation for the National Institute of Health Osteoarthritis Biomarkers Consortium study. Baseline and 24-month MRIs of 600 subjects were assessed. The presence of SHFP oedema (using 0-3 grading scale) and patellar morphology metrics were determined using baseline MRI. Quantitative patellar cartilage volume and semi-quantitative MRI osteoarthritis knee score (MOAKS) variables were extracted. The associations between SHFP oedema and patellar cartilage damage, bone marrow lesion (BML), osteophyte and morphology were evaluated in cross-sectional model. In longitudinal analysis, the associations between oedema and cartilage volume loss (defined using reliable change index) and MOAKS worsening were evaluated. In cross-sectional evaluations, the presence of SHFP oedema was associated with simultaneous lateral patellar cartilage/BML defects and inferior-medial patellar osteophyte size. A significant positive correlation between the degree of patella alta and SHFP oedema was detected (r = 0.259, p < 0.001). The presence of oedema was associated with 24-month cartilage volume loss (odds ratio (OR) 2.11, 95% confidence interval 1.46-3.06) and medial patellar BML size (OR 1.92 (1.15-3.21)) and number (OR 2.50 (1.29-4.88)) worsening. The optimal cut-off value for the grade of baseline SHFP oedema regarding both presence and worsening of patellar structural damage was ≥ 1 (presence of any SHFP hyperintensity). The presence of SHFP oedema could be considered as a predictor of future patellar cartilage loss and BML worsening, and an indicator of simultaneous cartilage, BML and osteophyte defects. • SHFP oedema was associated with simultaneous lateral patellar OA-related structural damage. • SHFP oedema was associated with longitudinal patellar cartilage loss over 24 months. • SHFP oedema could be considered as indicator and predictor

Thermo-aerodynamic efficiency of non-circular ducts with vortex enhancement of heat exchange in different types of compact heat exchangers

NASA Astrophysics Data System (ADS)

Vasilev, V. Ya; Nikiforova, S. A.

2018-03-01

Experimental studies of thermo-aerodynamic characteristics of non-circular ducts with discrete turbulators on walls and interrupted channels have confirmed the rational enhancement of convective heat transfer, in which the growth of heat transfer outstrips or equals the growth of aerodynamic losses. Determining the regularities of rational (energy-saving) enhancement of heat transfer and the proposed method for comparing the characteristics of smooth-channel (without enhancement) heat exchangers with effective analogs provide new results, confirming the high efficiency of vortex enhancement of convective heat transfer in non-circular ducts of plate-finned heat exchange surfaces. This allows creating heat exchangers with much smaller mass and volume for operation in energy-saving modes.

Conductive carbon tape used for support and mounting of both whole animal and fragile heat-treated tissue sections for MALDI MS imaging and quantitation.

PubMed

Goodwin, Richard J A; Nilsson, Anna; Borg, Daniel; Langridge-Smith, Pat R R; Harrison, David J; Mackay, C Logan; Iverson, Suzanne L; Andrén, Per E

2012-08-30

Analysis of whole animal tissue sections by MALDI MS imaging (MSI) requires effective sample collection and transfer methods to allow the highest quality of in situ analysis of small or hard to dissect tissues. We report on the use of double-sided adhesive conductive carbon tape during whole adult rat tissue sectioning of carboxymethyl cellulose (CMC) embedded animals, with samples mounted onto large format conductive glass and conductive plastic MALDI targets, enabling MSI analysis to be performed on both TOF and FT-ICR MALDI mass spectrometers. We show that mounting does not unduly affect small molecule MSI detection by analyzing tiotropium abundance and distribution in rat lung tissues, with direct on-tissue quantitation achieved. Significantly, we use the adhesive tape to provide support to embedded delicate heat-stabilized tissues, enabling sectioning and mounting to be performed that maintained tissue integrity on samples that had previously been impossible to adequately prepare section for MSI analysis. The mapping of larger peptidomic molecules was not hindered by tape mounting samples and we demonstrate this by mapping the distribution of PEP-19 in both native and heat-stabilized rat brains. Furthermore, we show that without heat stabilization PEP-19 degradation fragments can detected and identified directly by MALDI MSI analysis. Copyright © 2012 Elsevier B.V. All rights reserved.

Scale and geometry effects on heat-recirculating combustors

NASA Astrophysics Data System (ADS)

Chen, Chien-Hua; Ronney, Paul D.

2013-10-01

A simple analysis of linear and spiral counterflow heat-recirculating combustors was conducted to identify the dimensionless parameters expected to quantify the performance of such devices. A three-dimensional (3D) numerical model of spiral counterflow 'Swiss roll' combustors was then used to confirm and extend the applicability of the identified parameters. It was found that without property adjustment to maintain constant values of these parameters, at low Reynolds number (Re) smaller-scale combustors actually showed better performance (in terms of having lower lean extinction limits at the same Re) due to lower heat loss and internal wall-to-wall radiation effects, whereas at high Re, larger-scale combustors showed better performance due to longer residence time relative to chemical reaction time. By adjustment of property values, it was confirmed that four dimensionless parameters were sufficient to characterise combustor performance at all scales: Re, a heat loss coefficient (α), a Damköhler number (Da) and a radiative transfer number (R). The effect of diffusive transport effect (i.e. Lewis number) was found to be significant only at low Re. Substantial differences were found between the performance of linear and spiral combustors; these were explained in terms of the effects of the area exposed to heat loss to ambient and the sometimes detrimental effect of increasing heat transfer to adjacent outlet turns of the spiral exchanger. These results provide insight into the optimal design of small-scale combustors and choice of operation conditions.

Augmentation of heat transfer by longitudinal vortices in plate-fin heat exchangers with two rows of tubes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rodrigues, R. Jr.; Yanagihara, J.I.

1999-07-01

The thermal performance of fin-tube compact heat exchangers is highly affected by the thermal resistance occurring on the air side, which is much higher than the thermal resistance inside the tubes. Since this kind of heat exchanger is widely used in these days, with applications on air-conditioning, refrigeration, automobilistic industry and many other areas, the development of more efficient and cheaper heat exchangers is highly attractive, because it will permit the manufacturing of more competitive equipments. This work presents results of numerical simulations for fin-tube compact heat exchangers using smooth fins and longitudinal vortex generators. The computational model has twomore » rows of round tubes in staggered arrangement. Built-in delta winglet vortex generators were used, and its geometric dimensions were chosen according to the best results of literature. The steady-state numerical simulations were carried out at Re = 300, with a code based on the finite volume method. The typical configuration, where the vortex generators of both tube rows have identical parameters set, was compared with new ones where the vortex generators of the second row have different attack angles and positions. The global and local influence of vortex generators on heat transfer and flow losses are analyzed by comparison with a smooth fin model without vortex generators. The results show that a best heat transfer performance can be obtained by positioning the vortex generators of the second row at a particular position and angle of attack, when the increasing of the flow losses was smaller than the heat transfer enhancement achieved.« less

Quantitative analysis of tridymite and cristobalite crystallized in rice husk ash by heating.

PubMed

Shinohara, Yasushi; Kohyama, Norihiko

2004-04-01

The quantities of two forms of crystalline silica, tridymite and cristobalite, in heated rice husk ash (RHA) samples were determined by X-ray diffraction (XRD) and chemical methods. Two RHA samples, containing 93% SiO2 and 2-3% K2O, were prepared from charcoaled rice husk products and heated to above 900 degrees C. The crystalline silica made up over 60-80% of the total silica in the heated RHA samples based on the XRD analysis. The crystalline phases in the two samples were somewhat different: The sample heated in the temperature range of 900 to 1,200 degrees C contained 52-62% cristobalite and 10-17% tridymite, but the other sample heated at a comparable temperature, above 1,100 degrees C, contained 46-66% tridymite and 37-16% cristobalite. Based on a correlation of lower tridymite crystallization temperature with higher potassium content, it was concluded that higher potassium levels were responsible for this difference. The pyrophosphoric acid analysis did not give exact results in the evaluation of total crystalline silica content in these RHA samples. As the combustion of rice husk was considered to cover the demands for energy and silica resource in Asian countries, cristobalite and tridymite crystallized in RHA by burning of rice husk should be assessed precisely by XRD analysis and the airborne dust in relevant workplace be controlled.

Avian thermoregulation in the heat: evaporative cooling in five Australian passerines reveals within-order biogeographic variation in heat tolerance.

PubMed

McKechnie, Andrew E; Gerson, Alexander R; McWhorter, Todd J; Smith, Eric Krabbe; Talbot, William A; Wolf, Blair O

2017-07-01

Evaporative heat loss pathways vary among avian orders, but the extent to which evaporative cooling capacity and heat tolerance vary within orders remains unclear. We quantified the upper limits to thermoregulation under extremely hot conditions in five Australian passerines: yellow-plumed honeyeater ( Lichenostomus ornatus ; ∼17 g), spiny-cheeked honeyeater ( Acanthagenys rufogularis ; ∼42 g), chestnut-crowned babbler ( Pomatostomus ruficeps ; ∼52 g), grey butcherbird ( Cracticus torquatus ; ∼86 g) and apostlebird ( Struthidea cinerea ; ∼118 g). At air temperatures ( T a ) exceeding body temperature ( T b ), all five species showed increases in T b to maximum values around 44-45°C, accompanied by rapid increases in resting metabolic rate above clearly defined upper critical limits of thermoneutrality and increases in evaporative water loss (EWL) to levels equivalent to 670-860% of baseline rates at thermoneutral T a Maximum cooling capacity, quantified as the fraction of metabolic heat production dissipated evaporatively, ranged from 1.20 to 2.17, consistent with the known range for passerines, and well below the corresponding ranges for columbids and caprimulgids. Heat tolerance limit (HTL, the maximum T a tolerated) scaled positively with body mass, varying from 46°C in yellow-plumed honeyeaters to 52°C in a single apostlebird, but was lower than that of three southern African ploceid passerines investigated previously. We argue this difference is functionally linked to a smaller scope for increases in EWL above baseline levels. Our data reiterate the reliance of passerines in general on respiratory evaporative heat loss via panting, but also reveal substantial within-order variation in heat tolerance and evaporative cooling capacity. © 2017. Published by The Company of Biologists Ltd.

Heat strain in cold.

PubMed

Rintamäki, Hannu; Rissanen, Sirkka

2006-07-01

In spite of increased environmental cold stress, heat strain is possible also in a cold environment. The body heat balance depends on three factors: environmental thermal conditions, metabolic heat production and thermal insulation of clothing and other protective garments. As physical exercise may increase metabolic heat production from rest values by ten times or even more, the required thermal insulation of clothing may vary accordingly. However, in most outdoor work, and often in indoor cold work, too, the thermal insulation of clothing is impractical, difficult or impossible to adjust according to the changes in physical activity. This is especially true with whole body covering garments like chemical protective clothing. As a result of this imbalance, heat strain may develop. In cold all the signs of heat strain (core temperature above 38 degrees C, warm or hot thermal sensations, increased cutaneous circulation and sweating) may not be present at the same time. Heat strain in cold may be whole body heat strain or related only to torso or core temperature. Together with heat strain in torso or body core, there can be at the same time even cold strain in peripheral parts and/or superficial layers of the body. In cold environment both the preservation of insulation and facilitation of heat loss are important. Development of clothing design is still needed to allow easy adjustments of thermal insulation.

Accuracy of Blood Loss Measurement during Cesarean Delivery.

PubMed

Doctorvaladan, Sahar V; Jelks, Andrea T; Hsieh, Eric W; Thurer, Robert L; Zakowski, Mark I; Lagrew, David C

2017-04-01

Objective  This study aims to compare the accuracy of visual, quantitative gravimetric, and colorimetric methods used to determine blood loss during cesarean delivery procedures employing a hemoglobin extraction assay as the reference standard. Study Design  In 50 patients having cesarean deliveries blood loss determined by assays of hemoglobin content on surgical sponges and in suction canisters was compared with obstetricians' visual estimates, a quantitative gravimetric method, and the blood loss determined by a novel colorimetric system. Agreement between the reference assay and other measures was evaluated by the Bland-Altman method. Results  Compared with the blood loss measured by the reference assay (470 ± 296 mL), the colorimetric system (572 ± 334 mL) was more accurate than either visual estimation (928 ± 261 mL) or gravimetric measurement (822 ± 489 mL). The correlation between the assay method and the colorimetric system was more predictive (standardized coefficient = 0.951, adjusted R 2  = 0.902) than either visual estimation (standardized coefficient = 0.700, adjusted R 2  = 00.479) or the gravimetric determination (standardized coefficient = 0.564, adjusted R 2  = 0.304). Conclusion  During cesarean delivery, measuring blood loss using colorimetric image analysis is superior to visual estimation and a gravimetric method. Implementation of colorimetric analysis may enhance the ability of management protocols to improve clinical outcomes.

Accuracy of Blood Loss Measurement during Cesarean Delivery

PubMed Central

Doctorvaladan, Sahar V.; Jelks, Andrea T.; Hsieh, Eric W.; Thurer, Robert L.; Zakowski, Mark I.; Lagrew, David C.

2017-01-01

Objective This study aims to compare the accuracy of visual, quantitative gravimetric, and colorimetric methods used to determine blood loss during cesarean delivery procedures employing a hemoglobin extraction assay as the reference standard. Study Design In 50 patients having cesarean deliveries blood loss determined by assays of hemoglobin content on surgical sponges and in suction canisters was compared with obstetricians' visual estimates, a quantitative gravimetric method, and the blood loss determined by a novel colorimetric system. Agreement between the reference assay and other measures was evaluated by the Bland–Altman method. Results Compared with the blood loss measured by the reference assay (470 ± 296 mL), the colorimetric system (572 ± 334 mL) was more accurate than either visual estimation (928 ± 261 mL) or gravimetric measurement (822 ± 489 mL). The correlation between the assay method and the colorimetric system was more predictive (standardized coefficient = 0.951, adjusted R2 = 0.902) than either visual estimation (standardized coefficient = 0.700, adjusted R2 = 00.479) or the gravimetric determination (standardized coefficient = 0.564, adjusted R2 = 0.304). Conclusion During cesarean delivery, measuring blood loss using colorimetric image analysis is superior to visual estimation and a gravimetric method. Implementation of colorimetric analysis may enhance the ability of management protocols to improve clinical outcomes. PMID:28497007

Paralysis and heart failure precede ion balance disruption in heat-stressed European green crabs.

PubMed

Jørgensen, Lisa B; Overgaard, Johannes; MacMillan, Heath A

2017-08-01

Acute exposure of ectotherms to critically high temperatures causes injury and death, and this mortality has been associated with a number of physiological perturbations including impaired oxygen transport, loss of ion and water homeostasis, and neuronal failure. It is difficult to discern which of these factors, if any, is the proximate cause of heat injury because, for example, loss of ion homeostasis can impair neuromuscular function (including cardiac function), and conversely impaired oxygen transport reduces ATP supply and can thus reduce ion transport capacity. In this study we investigated if heat stress causes a loss of ion homeostasis in marine crabs and examined if such loss is related to heart failure. We held crabs (Carcinus maenas) at temperatures just below their critical thermal maximum and measured extracellular (hemolymph) and intracellular (muscle) ion concentrations over time. Analysis of Arrhenius plots for heart rates during heating ramps revealed a breakpoint temperature below which heart rate increased with temperature, and above which heart rate declined until complete cardiac failure. As hypothesised, heat stress reduced the Nernst equilibrium potentials of both K + and Na + , likely causing a depolarization of the membrane potential. To examine whether this loss of ion balance was likely to cause disruption of neuromuscular function, we exposed crabs to the same temperatures, but this time measured ion concentrations at the individual-specific times of complete paralysis (from which the crabs never recovered), and at the time of cardiac failure. Loss of ion balance was observed only after both paralysis and complete heart failure had occurred; indicating that the loss of neuromuscular function is not caused by a loss of ion homeostasis. Instead we suggest that the observed loss of ion balance may be linked to tissue damage related to heat death. Copyright © 2016 Elsevier Ltd. All rights reserved.

Heat removal using microclimate foot cooling: a thermal foot manikin study.

PubMed

Castellani, John W; Demes, Robert; Endrusick, Thomas L; Cheuvront, Samuel N; Montain, Scott J

2014-04-01

It has been proposed that microclimate cooling systems exploit the peripheral extremities because of more efficient heat transfer. The purpose of this study was to quantify, using a patented microclimate cooling technique, the heat transfer from the plantar surface of the foot for comparison to other commonly cooled body regions. A military boot was fitted with an insole embedded with a coiled, 1.27 m length of hollow tubing terminating in inlet and outlet valves. A thermal foot manikin with a surface temperature of 34 degrees C was placed in the boot and the valves were connected to a system that circulated water through the insole at a temperature of 20 degrees C and flow rate of 120 ml x min(-1). The manikin foot served as a constant heat source to determine heat transfer provided by the insole. Testing was done with the foot model dry and sweating at a rate of 500 ml x h(- 1) x m(-2). Climatic chamber conditions were 30 degrees C with 30% RH. Heat loss was approximately 4.1 +/- 0.1 and approximately 7.7 +/- 0.3 W from the dry and sweating foot models, respectively. On a relative scale, the heat loss was 3.0 W and 5.5 W per 1% (unit) body surface area, respectively, for the dry and sweating conditions. The relative heat loss afforded by plantar foot cooling was similar compared to other body regions, but the absolute amount of heat removal is unlikely to make an impact on whole body heat balance.

Atlantic meridional heat transports computed from balancing Earth's energy locally: AMOC and Ocean Meridional Heat Transport

DOE Office of Scientific and Technical Information (OSTI.GOV)

Trenberth, Kevin E.; Fasullo, John T.

The Atlantic Meridional Overturning Circulation plays a major role in moving heat and carbon around in the ocean. A new estimate of ocean heat transports for 2000 through 2013 throughout the Atlantic is derived. Top-of-atmosphere radiation is combined with atmospheric reanalyses to estimate surface heat fluxes and combined with vertically integrated ocean heat content to estimate ocean heat transport divergence as a residual. Atlantic peak northward ocean heat transports average 1.18 ± 0.13PW (1 sigma) at 15°N but vary considerably in latitude and time. Results agree well with observational estimates at 26.5°N from the RAPID array, but for 2004–2013 themore » meridional heat transport is 1.00 ± 0.11PW versus 1.23 ± 0.11PW for RAPID. In addition, these results have no hint of a trend, unlike the RAPID results. Finally, strong westerlies north of a meridian drive ocean currents and an ocean heat loss into the atmosphere that is exacerbated by a decrease in ocean heat transport northward.« less

Atlantic meridional heat transports computed from balancing Earth's energy locally: AMOC and Ocean Meridional Heat Transport

DOE PAGES

Trenberth, Kevin E.; Fasullo, John T.

2017-02-18

The Atlantic Meridional Overturning Circulation plays a major role in moving heat and carbon around in the ocean. A new estimate of ocean heat transports for 2000 through 2013 throughout the Atlantic is derived. Top-of-atmosphere radiation is combined with atmospheric reanalyses to estimate surface heat fluxes and combined with vertically integrated ocean heat content to estimate ocean heat transport divergence as a residual. Atlantic peak northward ocean heat transports average 1.18 ± 0.13PW (1 sigma) at 15°N but vary considerably in latitude and time. Results agree well with observational estimates at 26.5°N from the RAPID array, but for 2004–2013 themore » meridional heat transport is 1.00 ± 0.11PW versus 1.23 ± 0.11PW for RAPID. In addition, these results have no hint of a trend, unlike the RAPID results. Finally, strong westerlies north of a meridian drive ocean currents and an ocean heat loss into the atmosphere that is exacerbated by a decrease in ocean heat transport northward.« less

Quantitative precorneal disposition of topically applied pilocarpine nitrate in rabbit eyes.

PubMed

Patton, T F; Robinson, J R

1976-09-01

The present study was designed to quantitate the influence of several precorneal factors on the disposition of topically applied ophthalmic drugs. With tritiated pilocarpine nitrate methodology was developed for in vivo assessment of the relative contribution of tear turnover, instilled solution drainage, and nonproductive absorption to the loss of drug from the precorneal area. Studies were conducted in both awake and anesthetized rabbits whose drainage ducts were either unobstructed or plugged, and the loss of drug was monitored directly from the precorneal area or as appearance in the aqueous humor. By selective variation in experimental conditions, the influence of tear turnover, instilled solution drainage, and nonproductive absorption on ocular drug bioavailability was separately studied and quantitated. Instilled solution drainage was by far the largest contributing factor in the loss of drug from the precorneal area of the eye and, in the range of instilled volumes normally employed, tear turnover played a relatively minor role in drug loss. Compared to the cornea, precorneal tissue other than the cornea has a considerably greater surface area and thus is a potentially signifanct route for drug loss. However, under normal circumstances, loss by this route was minimal as compared to loss via instilled solution drainage.

Developing NanoFoil-Heated Thin-Film Thermal Battery

DTIC Science & Technology

2013-09-01

buffer discs (in gray) sandwiching the NanoFoil disc (in yellow). Two Microtherm discs (in dark gray) bracketed the sandwich to prevent excessive heat...of the fuse strip with a Microtherm disc. Cathode Electrolyte Anode Microtherm Heat paper NanoFoil Buffer Agilent 34970A 606.5 Nichrome wire Maccor...gray) sandwiching the NanoFoil disc (in yellow). Two Microtherm discs (in dark gray) bracketed the sandwich to prevent excessive heat loss

Performance improvement of optical fiber coupler with electric heating versus gas heating.

PubMed

Shuai, Cijun; Gao, Chengde; Nie, Yi; Peng, Shuping

2010-08-20

Gas heating has been widely used in the process of fused biconical tapering. However, as the instability and asymmetric flame temperature of gas heating exist, the performance of the optical devices fabricated by this method was affected. To overcome the problems resulting from gas combustion, an electric heater is designed and manufactured using a metal-ceramic (MoSi(2)) as a heating material. Our experimental data show that the fused-taper machine with an electric heater has improved the performance of optical devices by increasing the consistency of the extinction ratio, excess loss, and the splitting ratio over that of the previous gas heating mode. Microcrystallizations and microcracks were observed at the fused region of the polarization-maintaining (PM) fiber coupler and at the taper region with scanning electron microscopy and atomic force microscopy respectively. The distribution of the microcrystallizations and microcracks are nonuniform along the fiber with gas heating, while their distribution is rather uniform with electric heating. These findings show that the novel optical fiber coupler with an electric heater has improved the performance of optical fiber devices by affecting the consistency of the optical parameters and micromorphology of the surface of PM fiber.

A tutorial in displaying mass spectrometry-based proteomic data using heat maps.

PubMed

Key, Melissa

2012-01-01

Data visualization plays a critical role in interpreting experimental results of proteomic experiments. Heat maps are particularly useful for this task, as they allow us to find quantitative patterns across proteins and biological samples simultaneously. The quality of a heat map can be vastly improved by understanding the options available to display and organize the data in the heat map. This tutorial illustrates how to optimize heat maps for proteomics data by incorporating known characteristics of the data into the image. First, the concepts used to guide the creating of heat maps are demonstrated. Then, these concepts are applied to two types of analysis: visualizing spectral features across biological samples, and presenting the results of tests of statistical significance. For all examples we provide details of computer code in the open-source statistical programming language R, which can be used for biologists and clinicians with little statistical background. Heat maps are a useful tool for presenting quantitative proteomic data organized in a matrix format. Understanding and optimizing the parameters used to create the heat map can vastly improve both the appearance and the interoperation of heat map data.

Toward a Molecular Understanding of Noise-Induced Hearing Loss

DTIC Science & Technology

2017-10-01

cell, SAHA, Heat shock, sex differences 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT 18. NUMBER OF PAGES 19a. NAME OF RESPONSIBLE PERSON...threshold shift, Temporary threshold shift, Noise induced hearing loss, Ribotag, RNA-seq, Hair cell, Supporting cell, SAHA, Heat shock, Sex ...also sex -specific. TTS-inducing noise exposure: crosses, calibration, validation cytocochleograms, noise exposure, tissue harvesting, polysome IP

Analysis of sensible heat exchanges from a thermal manikin.

PubMed

Quintela, Divo; Gaspar, Adélio; Borges, Carlos

2004-09-01

The present work is dedicated to the analysis of dry heat exchanges as measured by a thermal manikin placed in still air. We believe that the understanding of some fundamental aspects governing fluid flow and heat transfer around three-dimensional bodies such as human beings deserves appropriate attention. This should be of great significance for improving physiological models concerned with thermal exposures. The potential interest of such work can be directed towards quite distinct targets such as working conditions, sports, the military, or healthcare personnel and patients. In the present study, we made use of a climate chamber and an articulated thermal manikin of the Pernille type, with 16 body parts. The most common occidental postures (standing, sitting and lying) were studied. In order to separate heat losses due to radiation and convection, the radiative heat losses of the manikin were significantly reduced by means of a shiny aluminium coating, which was carefully applied to the artificial skin. The air temperature within the test chamber was varied between 13 degrees C and 29 degrees C. The corresponding mean differences between the skin and the operative temperatures changed from 3.8 degrees C up to 15.8 degrees C. The whole-body heat transfer coefficients by radiation and convection for both standing and sitting postures are in good agreement with those in the published literature. The lying posture appears to be more efficient for losing heat by convection. This is confirmed when the heat losses of each individual part are considered. The proposed correlations for the whole body suggest that natural convection is mainly laminar.

Proteomic analysis to unravel the effect of heat stress on gene expression and milk synthesis in bovine mammary epithelial cells.

PubMed

Li, Lian; Wang, Yiru; Li, Chengmin; Wang, Genlin

2017-12-01

Heat stress can play a negative effect on milk yield and composition of dairy cattle, leading to immeasurable economic loss. The basic components of the mammary gland are the alveoli; these alveolar mammary epithelial cells reflect the milk producing ability of dairy cows. In this study, we exposed bovine mammary epithelial cells to heat stress and compared them to a control group using isobaric tags for relative and absolute quantitation combined with liquid chromatography coupled with tandem mass spectrometry. Compared with a control group, 104 differentially elevated proteins (>1.3-fold) and 167 decreased proteins (<0.77-fold) were identified in the heat treatment group. Gene Ontology analysis identified a majority of the differentially expressed proteins are associated in cell-substrate junction assembly, catabolic processes and metabolic processes. Some of these significantly regulated proteins were related to the synthesis and secretion of milk, such as milk protein and fat. This finding was further supported by the results obtained from the reduced β-casein expression through the system of plasminogen activator - plasminogen - plasmin and decreased fatty acid synthase could partly explain why milk fat synthesis ability of dairy cows decreased under heat stress. Our results highlight the effects of heat stress on synthesis of milk protein and fat, thus providing additional clues for further studies of heat stress on dairy milk production. © 2017 Japanese Society of Animal Science.

Does attenuated skin blood flow lower sweat rate and the critical environmental limit for heat balance during severe heat exposure?

PubMed

Cramer, Matthew N; Gagnon, Daniel; Crandall, Craig G; Jay, Ollie

2017-02-01

What is the central question of this study? Does attenuated skin blood flow diminish sweating and reduce the critical environmental limit for heat balance, which indicates maximal heat loss potential, during severe heat stress? What is the main finding and its importance? Isosmotic hypovolaemia attenuated skin blood flow by ∼20% but did not result in different sweating rates, mean skin temperatures or critical environmental limits for heat balance compared with control and volume-infusion treatments, suggesting that the lower levels of skin blood flow commonly observed in aged and diseased populations may not diminish maximal whole-body heat dissipation. Attenuated skin blood flow (SkBF) is often assumed to impair core temperature (T c ) regulation. Profound pharmacologically induced reductions in SkBF (∼85%) lead to impaired sweating, but whether the smaller attenuations in SkBF (∼20%) more often associated with ageing and certain diseases lead to decrements in sweating and maximal heat loss potential is unknown. Seven healthy men (28 ± 4 years old) completed a 30 min equilibration period at 41°C and a vapour pressure (P a ) of 2.57 kPa followed by incremental steps in P a of 0.17 kPa every 6 min to 5.95 kPa. Differences in heat loss potential were assessed by identifying the critical vapour pressure (P crit ) at which an upward inflection in T c occurred. The following three separate treatments elicited changes in plasma volume to achieve three distinct levels of SkBF: control (CON); diuretic-induced isosmotic dehydration to lower SkBF (DEH); and continuous saline infusion to maintain SkBF (SAL). The T c , mean skin temperature (T sk ), heart rate, mean laser-Doppler flux (forearm and thigh; LDF mean ), mean local sweat rate (forearm and thigh; LSR mean ) and metabolic rate were measured. In DEH, a 14.2 ± 5.7% lower plasma volume resulted in a ∼20% lower LDF mean in perfusion units (PU) (DEH, 139 ± 23 PU; CON, 176 ± 22 PU; and SAL

Rapid thermal process by RF heating of nano-graphene layer/silicon substrate structure: Heat explosion theory approach

NASA Astrophysics Data System (ADS)

Sinder, M.; Pelleg, J.; Meerovich, V.; Sokolovsky, V.

2018-03-01

RF heating kinetics of a nano-graphene layer/silicon substrate structure is analyzed theoretically as a function of the thickness and sheet resistance of the graphene layer, the dimensions and thermal parameters of the structure, as well as of cooling conditions and of the amplitude and frequency of the applied RF magnetic field. It is shown that two regimes of the heating can be realized. The first one is characterized by heating of the structure up to a finite temperature determined by equilibrium between the dissipated loss power caused by induced eddy-currents and the heat transfer to environment. The second regime corresponds to a fast unlimited temperature increase (heat explosion). The criterions of realization of these regimes are presented in the analytical form. Using the criterions and literature data, it is shown the possibility of the heat explosion regime for a graphene layer/silicon substrate structure at RF heating.

Radiant energy and insensible water loss in the premature newborn infant nursed under a radiant warmer.

PubMed

Baumgart, S

1982-10-01

Radiant warmers are a powerful and efficient source of heat serving to warm the cold-stressed infant acutely and to provide uninterrupted maintenance of body temperature despite a multiplicity of nursing, medical, and surgical procedures required to care for the critically ill premature newborn in today's intensive care nursery. A recognized side-effect of radiant warmer beds is the now well-documented increase in insensible water loss through evaporation from an infant's skin. Particularly the very-low-birth-weight, severely premature, and critically ill neonate is subject to this increase in evaporative water loss. The clinician caring for the infant is faced with the difficult problem of fluid and electrolyte balance, which requires vigilant monitoring of all parameters of fluid homeostasis. Compounding these difficulties, other portions of the electromagnetic spectrum (for example, phototherapy) may affect an infant's fluid metabolism by mechanisms that are not well understood. The role of plastic heat shielding in reducing large insensible losses in infants nursed on radiant warmer beds is currently under intense investigation. Apparently, convective air currents and not radiant heat energy may be the cause of the observed increase in insensible water loss in the intensive care nursery. A thin plastic blanket may be effective in reducing evaporative water loss by diminishing an infant's exposure to convective air currents while being nursed on an open radiant warmer bed. A rigid plastic body hood, although effective as a radiant heat shield, is not as effective in preventing exposure to convection in the intensive care nursery and, therefore, is not as effective as the thin plastic blanket in reducing insensible water loss. Care should be exercised in determining the effect of heat shielding on all parameters of heat exchange (convection, evaporation, and radiation) before application is made to the critically ill premature infant nursed on an open radiant

Management of heat stress in the livestock industry

USDA-ARS?s Scientific Manuscript database

Heat stress costs the animal industry over $1.7 billion annually. Annual losses average $369 million in the beef cattle industry and $299 million in the swine industry. The impacts of a single heat stress event on individual animals are quite varied. Brief events often cause little or no effect. ...

Evaluation of Energy Efficiency Performance of Heated Windows

NASA Astrophysics Data System (ADS)

Jammulamadaka, Hari Swarup

The study about the evaluation of the performance of the heated windows was funded by the WVU Research Office as a technical assistance award at the 2014 TransTech Energy Business Development Conference to the Green Heated Glass company/project owned by Frank Dlubak. The award supports a WVU researcher to conduct a project important for commercialization. This project was awarded to the WVU Industrial Assessment Center in 2015. The current study attempted to evaluate the performance of the heated windows by developing an experimental setup to test the window at various temperatures by varying the current input to the window. The heated double pane window was installed in an insulated box. A temperature gradient was developed across the window by cooling one side of the window using gel based ice packs. The other face of the window was heated by passing current at different wattages through the window. The temperature of the inside and outside panes, current and voltage input, room and box temperature were recorded, and used to calculate the apparent R-value of the window when not being heated vs when being heated. It has been concluded from the study that the heated double pane window is more effective in reducing heat losses by as much as 50% than a non-heated double pane window, if the window temperature is maintained close to the room temperature. If the temperature of the window is much higher than the room temperature, the losses through the window appear to increase beyond that of a non-heated counterpart. The issues encountered during the current round of experiments are noted, and recommendations provided for future studies.

Overview of NASA supported Stirling thermodynamic loss research

NASA Technical Reports Server (NTRS)

Tew, Roy C.; Geng, Steven M.

1992-01-01

NASA is funding research to characterize Stirling machine thermodynamic losses. NASA's primary goal is to improve Stirling design codes to support engine development for space and terrestrial power. However, much of the fundamental data is applicable to Stirling cooling and heat pump applications. The research results are reviewed. Much was learned about oscillating flow hydrodynamics, including laminar/turbulent transition, and tabulated data was documented for further analysis. Now, with a better understanding of the oscillating flow field, it is time to begin measuring the effects of oscillating flow and oscillating pressure level on heat transfer in heat exchanger flow passages and in cylinders.

Effects of the distribution density of a biomass combined heat and power plant network on heat utilisation efficiency in village-town systems.

PubMed

Zhang, Yifei; Kang, Jian

2017-11-01

The building of biomass combined heat and power (CHP) plants is an effective means of developing biomass energy because they can satisfy demands for winter heating and electricity consumption. The purpose of this study was to analyse the effect of the distribution density of a biomass CHP plant network on heat utilisation efficiency in a village-town system. The distribution density is determined based on the heat transmission threshold, and the heat utilisation efficiency is determined based on the heat demand distribution, heat output efficiency, and heat transmission loss. The objective of this study was to ascertain the optimal value for the heat transmission threshold using a multi-scheme comparison based on an analysis of these factors. To this end, a model of a biomass CHP plant network was built using geographic information system tools to simulate and generate three planning schemes with different heat transmission thresholds (6, 8, and 10 km) according to the heat demand distribution. The heat utilisation efficiencies of these planning schemes were then compared by calculating the gross power, heat output efficiency, and heat transmission loss of the biomass CHP plant for each scenario. This multi-scheme comparison yielded the following results: when the heat transmission threshold was low, the distribution density of the biomass CHP plant network was high and the biomass CHP plants tended to be relatively small. In contrast, when the heat transmission threshold was high, the distribution density of the network was low and the biomass CHP plants tended to be relatively large. When the heat transmission threshold was 8 km, the distribution density of the biomass CHP plant network was optimised for efficient heat utilisation. To promote the development of renewable energy sources, a planning scheme for a biomass CHP plant network that maximises heat utilisation efficiency can be obtained using the optimal heat transmission threshold and the nonlinearity

Heat losses and thermal imaging of ferroic components

NASA Astrophysics Data System (ADS)

Ilyashenko, S. E.; Ivanova, A. I.; Gasanov, O. V.; Grechishkin, R. M.; Tretiakov, S. A.; Yushkov, K. B.; Linde, B. B. J.

2015-03-01

A study is made of spatial and temporal temperature variations in working devices based on ferroic functional materials. The measurement of the sample's temperature is complemented with direct observation of its distribution over the sample surface. For the latter purpose a thermovision infrared videocamera technique was employed. Specific features of the temperature distribution and its evolution during heating and cooling of a number of piezoelectric, acoustooptic and shape memory components are revealed. Examples of hot spot observations indicative of structural defects in the samples under study are given thus suggesting the use of thermal vision for nondestructive testing. A proposal is made to combine the thermovision method with that of thermomagnetic analysis for the study of ferromagnetic shape memory alloys.

Heat transfer in a compact tubular heat exchanger with helium gas at 3.5 MPa

NASA Technical Reports Server (NTRS)

Olson, Douglas A.; Glover, Michael P.

1990-01-01

A compact heat exchanger was constructed consisting of circular tubes in parallel brazed to a grooved base plate. This tube specimen heat exchanger was tested in an apparatus which radiatively heated the specimen on one side at a heat flux of up to 54 W/sq cm, and cooled the specimen with helium gas at 3.5 MPa and Reynolds numbers of 3000 to 35,000. The measured friction factor of the tube specimen was lower than that of a circular tube with fully developed turbulent flow, although the uncertainty was high due to entrance and exit losses. The measured Nusselt number, when modified to account for differences in fluid properties between the wall and the cooling fluid, agreed with past correlations for fully developed turbulent flow in circular tubes.

Evidence that exercise-induced heat storage is dependent on adrenomedullary secretion.

PubMed

Rodrigues, A G; Lima, N R V; Coimbra, C C; Marubayashi, U

2008-06-09

To investigate the influence of medullary adrenal secretion on thermoregulation during exercise, Phy (Eserine, 5x10(-3) M) was injected into the lateral cerebral ventricle of normal (INT) or bilaterally adrenodemedullated (ADM) untrained rats. Body temperature (Tb) and metabolic rate were measured in the rats while they were exercising on a treadmill (20 m min(-1), 5% inclination) until fatigue or while they were at rest after drug injection. In resting rats, Phy increased oxygen consumption in both INT or ADM rats without any effect on core temperature. During the dynamic phase of exercise (first 20 min), ADM attenuated the exercise-induced increase in core temperature (0.86+/-0.12 degrees C ADM Sal vs 1.48+/-0.21 degrees C INT Sal), thus reducing heat storage (HS) levels. Icv injection of Phy in ADM rats significantly reduced the increase in Tb (0.012+/-0.10 degrees C min(-1) Phy vs 0.042+/-0.006 degrees C min(-1) Sal; p<0.02) and HS (65.8+/-56.1 cal Phy vs 207.7+/-32.7 cal Sal; p<0.04) compared to ADM Sal rats. In conclusion, the exercise-induced increase in heat storage was attenuated by adrenodemedullation in rats. Furthermore, the activation of heat loss mechanisms by the central cholinergic system during exercise occurs independently of adrenal medullary secretion suppression and can be improved by previous adrenodemedullation. Our data indicate the existence of a dual mechanism of heat loss control during the dynamic phase of exercise: one involving sympathoadrenal system activation that impairs heat loss and another that counteracts the increased sympathoadrenal activity through the hypothalamic cholinergic system to promote heat loss.

Analysis of beam loss induced abort kicker instability

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang W.; Sandberg, J.; Ahrens, L.

2012-05-20

Through more than a decade of operation, we have noticed the phenomena of beam loss induced kicker instability in the RHIC beam abort systems. In this study, we analyze the short term beam loss before abort kicker pre-fire events and operation conditions before capacitor failures. Beam loss has caused capacitor failures and elevated radiation level concentrated at failed end of capacitor has been observed. We are interested in beam loss induced radiation and heat dissipation in large oil filled capacitors and beam triggered thyratron conduction. We hope the analysis result would lead to better protection of the abort systems andmore » improved stability of the RHIC operation.« less

Quantitative assessment and characterization of glenoid bone loss in a spectrum of patients with glenohumeral osteoarthritis.

PubMed

Lombardo, D J; Khan, J; Prey, B; Zhang, L; Petersen-Fitts, G R; Sabesan, V J

2016-12-01

Eccentric posterior bone loss and associated glenoid retroversion represent challenges to glenoid placement during total shoulder arthroplasty. This bone loss can lead to poor stability and perforation of the glenoid during arthroplasty. The purpose of this study was to evaluate the morphology of glenoid bone loss for a spectrum of osteoarthritis patients using 3D computed tomography imaging and simulation software. This study included 29 patients with glenohumeral osteoarthritis treated with shoulder arthroplasty. Three-dimensional reconstruction of preoperative CT images was performed. Glenoid bone loss was measured at ten, vertically equidistant axial planes along the glenoid surface at four distinct anterior-posterior points on each plane. The images were fitted with modeled pegged glenoid implants to predict glenoid perforation. The 3D maps demonstrated greatest average bone loss posteriorly in the AP plane at the central axis of the glenoid in the SI plane. The average amount of bone loss was 3.85 mm. Walch A2 and B1 shoulders showed more central bone loss, while Walch B2 shoulders displayed more posterior and inferior bone loss. Patients with predicted peg perforation displayed significantly greater bone loss than those without predicted peg perforation (p = 0.037). Peg perforation was most common in Walch B2 shoulders occurring in the posterior direction involving the central and posterior-inferior peg. These data demonstrate an anatomic pattern of glenoid bone loss for different classes of glenohumeral arthritis. These findings can be used to develop various models of glenoid bone loss to guide surgeons, predict failures, and develop better glenoid implants. This study has been approved by the Cleveland Clinic IRB: Number 6235.

Local Heat Transfer for Finned-Tube Heat Exchangers using Oval Tubes

DOE Office of Scientific and Technical Information (OSTI.GOV)

O'Brien, James Edward; Sohal, Manohar Singh

2000-08-01

This paper presents the results of an experimental study of forced convection heat transfer in a narrow rectangular duct fitted with either a circular tube or an elliptical tube in crossflow. The duct was designed to simulate a single passage in a fin-tube heat exchanger. Heat transfer measurements were obtained using a transient technique in which a heated airflow is suddenly introduced to the test section. High-resolution local fin-surface temperature distributions were obtained at several times after initiation of the transient using an imaging infrared camera. Corresponding local fin-surface heat transfer coefficient distributions were then calculated from a locally appliedmore » one-dimensional semi-infinite inverse heat conduction model. Heat transfer results were obtained over an airflow rate ranging from 1.56 x 10-3 to 15.6 x 10-3 kg/s. These flow rates correspond to a duct-height Reynolds number range of 630 – 6300 with a duct height of 1.106 cm and a duct width-toheight ratio, W/H, of 11.25. The test cylinder was sized such that the diameter-to-duct height ratio, D/H is 5. The elliptical tube had an aspect ratio of 3:1 and a/H equal to 4.33. Results presented in this paper reveal visual and quantitative details of local fin-surface heat transfer distributions in the vicinity of circular and oval tubes and their relationship to the complex horseshoe vortex system that forms in the flow stagnation region. Fin surface stagnation-region Nusselt numbers are shown to be proportional to the square-root of Reynolds number.« less

Heat Transfer Enhancement for Finned-tube Heat Exchangers with Winglets

DOE Office of Scientific and Technical Information (OSTI.GOV)

O'Brien, James Edward; Sohal, Manohar Singh

2000-11-01

This paper presents the results of an experimental study of forced convection heat transfer in a narrow rectangular duct fitted with a circular tube and/or a delta-winglet pair. The duct was designed to simulate a single passage in a fin-tube heat exchanger. Heat transfer measurements were obtained using a transient technique in which a heated airflow is suddenly introduced to the test section. High-resolution local fin-surface temperature distributions were obtained at several times after initiation of the transient using an imaging infrared camera. Corresponding local fin-surface heat transfer coefficient distributions were then calculated from a locally applied one-dimensional semi-infinite inversemore » heat conduction model. Heat transfer results were obtained over an airflow rate ranging from 1.51 x 10-3 to 14.0 x 10-3 kg/s. These flow rates correspond to a duct-height Reynolds number range of 670 – 6300 with a duct height of 1.106 cm and a duct width-toheight ratio, W/H, of 11.25. The test cylinder was sized such that the diameter-to-duct height ratio, D/H is 5. Results presented in this paper reveal visual and quantitative details of local fin-surface heat transfer distributions in the vicinity of a circular tube, a delta-winglet pair, and a combination of a circular tube and a delta-winglet pair. Comparisons of local and average heat transfer distributions for the circular tube with and without winglets are provided. Overall mean finsurface Nusselt-number results indicate a significant level of heat transfer enhancement associated with the deployment of the winglets with the circular cylinder. At the lowest Reynolds numbers (which correspond to the laminar operating conditions of existing geothermal air-cooled condensers), the enhancement level is nearly a factor of two. At higher Reynolds numbers, the enhancement level is close to 50%.« less

Estimation of postfire nutrient loss in the Florida everglades.

PubMed

Qian, Y; Miao, S L; Gu, B; Li, Y C

2009-01-01

Postfire nutrient release into ecosystem via plant ash is critical to the understanding of fire impacts on the environment. Factors determining a postfire nutrient budget are prefire nutrient content in the combustible biomass, burn temperature, and the amount of combustible biomass. Our objective was to quantitatively describe the relationships between nutrient losses (or concentrations in ash) and burning temperature in laboratory controlled combustion and to further predict nutrient losses in field fire by applying predictive models established based on laboratory data. The percentage losses of total nitrogen (TN), total carbon (TC), and material mass showed a significant linear correlation with a slope close to 1, indicating that TN or TC loss occurred predominantly through volatilization during combustion. Data obtained in laboratory experiments suggest that the losses of TN, TC, as well as the ratio of ash total phosphorus (TP) concentration to leaf TP concentration have strong relationships with burning temperature and these relationships can be quantitatively described by nonlinear equations. The potential use of these nonlinear models relating nutrient loss (or concentration) to temperature in predicting nutrient concentrations in field ash appear to be promising. During a prescribed fire in the northern Everglades, 73.1% of TP was estimated to be retained in ash while 26.9% was lost to the atmosphere, agreeing well with the distribution of TP during previously reported wild fires. The use of predictive models would greatly reduce the cost associated with measuring field ash nutrient concentrations.

Multigrid-based reconstruction algorithm for quantitative photoacoustic tomography

PubMed Central

Li, Shengfu; Montcel, Bruno; Yuan, Zhen; Liu, Wanyu; Vray, Didier

2015-01-01

This paper proposes a multigrid inversion framework for quantitative photoacoustic tomography reconstruction. The forward model of optical fluence distribution and the inverse problem are solved at multiple resolutions. A fixed-point iteration scheme is formulated for each resolution and used as a cost function. The simulated and experimental results for quantitative photoacoustic tomography reconstruction show that the proposed multigrid inversion can dramatically reduce the required number of iterations for the optimization process without loss of reliability in the results. PMID:26203371

A Prototype Flux-Plate Heat-Flow Sensor for Venus Surface Heat-Flow Determinations

NASA Technical Reports Server (NTRS)

Morgan, Paul; Reyes, Celso; Smrekar, Suzanne E.

2005-01-01

Venus is the most Earth-like planet in the Solar System in terms of size, and the densities of the two planets are almost identical when selfcompression of the two planets is taken into account. Venus is the closest planet to Earth, and the simplest interpretation of their similar densities is that their bulk compositions are almost identical. Models of the thermal evolution of Venus predict interior temperatures very similar to those indicated for the regions of Earth subject to solid-state convection, but even global analyses of the coarse Pioneer Venus elevation data suggest Venus does not lose heat by the same primary heat loss mechanism as Earth, i.e., seafloor spreading. The comparative paucity of impact craters on Venus has been interpreted as evidence for relatively recent resurfacing of the planet associated with widespread volcanic and tectonic activity. The difference in the gross tectonic styles of Venus and Earth, and the origins of some of the enigmatic volcano-tectonic features on Venus, such as the coronae, appear to be intrinsically related to Venus heat loss mechanism(s). An important parameter in understanding Venus geological evolution, therefore, is its present surface heat flow. Before the complications of survival in the hostile Venus surface environment were tackled, a prototype fluxplate heat-flow sensor was built and tested for use under synthetic stable terrestrial surface conditions. The design parameters for this prototype were that it should operate on a conforming (sand) surface, with a small, self-contained power and recording system, capable of operating without servicing for at least several days. The precision and accuracy of the system should be < 5 mW/sq m. Additional information is included in the original extended abstract.

Dry heat loses of newborn baby in infant care bed: use of a thermal manikin

NASA Astrophysics Data System (ADS)

Ostrowski, Ziemowit; Rojczyk, Marek; Szczygieł, Ireneusz; Łaszczyk, Joanna; Nowak, Andrzej J.

2016-09-01

The energy balance and heat exchange for newborn baby in infant care bed environment (radiant warmer) are considered. The present study was performed to assess the body dry heat loss from an infant in radiant warmer, using copper cast anthropomorphic thermal manikin and controlled climate chamber laboratory setup. The total body dry heat losses were measured for varying manikin surface temperatures (nine levels between 32.5oC and 40.1oC) and ambient air temperatures (five levels between 23.5oC and 29.7oC). Radiant heat losses were estimated based on measured climate chamber wall temperatures. After subtracting radiant part, resulting convective heat loses are compared with computed ones, based on Nu correlations for common geometries. Simplified geometry of newborn baby was represented as: (a) single cylinder and (b) weighted sum of 5 cylinders and sphere. The computed values are significantly overestimated relative to measured ones by: 28.8% (23.5%) for (a) and 40.9% (25.2%) for (b). This shows that use of adopted general purpose correlations for approximation of convective heat losses of newborn baby can lead to substantial errors, hence approximation formula is proposed. The thermal manikin appears to provide a precise method for the noninvasive assessment of thermal conditions in neonatal care.

Application of horizontal spiral coil heat exchanger for volatile organic compounds (VOC) emission control.

PubMed

Deshpande, P M; Dawande, S D

2013-04-01

The petroleum products have wide range of volatility and are required to be stored in bulk. The evaporation losses are significant and it is a economic as well as environmental concern, since evaporative losses of petroleum products cause increased VOC in ambient air. Control of these losses poses a major problem for the storage tank designers. Ever rising cost of petroleum products further adds to the gravity of the problem. Condensation is one of the technologies for reducing volatile organic compounds emissions. Condensation is effected by condenser, which is basically a heat exchanger and the heat exchanger configuration plays an important role. The horizontal spiral coil heat exchanger is a promising configuration that finds an application in VOC control. This paper attempts to understand underlying causes of emissions and analyse the option of horizontal spiral coil heat exchanger as vent condenser.

Southern Ocean air-sea heat flux, SST spatial anomalies, and implications for multi-decadal upper ocean heat content trends.

NASA Astrophysics Data System (ADS)

Tamsitt, V. M.; Talley, L. D.; Mazloff, M. R.

2014-12-01

The Southern Ocean displays a zonal dipole (wavenumber one) pattern in sea surface temperature (SST), with a cool zonal anomaly in the Atlantic and Indian sectors and a warm zonal anomaly in the Pacific sector, associated with the large northward excursion of the Malvinas and southeastward flow of the Antarctic Circumpolar Current (ACC). To the north of the cool Indian sector is the warm, narrow Agulhas Return Current (ARC). Air-sea heat flux is largely the inverse of this SST pattern, with ocean heat gain in the Atlantic/Indian, cooling in the southeastward-flowing ARC, and cooling in the Pacific, based on adjusted fluxes from the Southern Ocean State Estimate (SOSE), a ⅙° eddy permitting model constrained to all available in situ data. This heat flux pattern is dominated by turbulent heat loss from the ocean (latent and sensible), proportional to perturbations in the difference between SST and surface air temperature, which are maintained by ocean advection. Locally in the Indian sector, intense heat loss along the ARC is contrasted by ocean heat gain of 0.11 PW south of the ARC. The IPCC AR5 50 year depth-averaged 0-700 m temperature trend shows surprising similarities in its spatial pattern, with upper ocean warming in the ARC contrasted by cooling to the south. Using diagnosed heat budget terms from the most recent (June 2014) 6-year run of the SOSE we find that surface cooling in the ARC is balanced by heating from south-eastward advection by the current whereas heat gain in the ACC is balanced by cooling due to northward Ekman transport driven by strong westerly winds. These results suggest that spatial patterns in multi-decadal upper ocean temperature trends depend on regional variations in upper ocean dynamics.

Heat stabilization of blood spot samples for determination of metabolically unstable drug compounds

PubMed Central

Blessborn, Daniel; Sköld, Karl; Zeeberg, David; Kaewkhao, Karnrawee; Sköld, Olof; Ahnoff, Martin

2014-01-01

Background Sample stability is critical for accurate analysis of drug compounds in biosamples. The use of additives to eradicate the enzymatic activity causing loss of these analytes has its limitations. Results A novel technique for sample stabilization by rapid, high-temperature heating was used. The stability of six commercial drugs in blood and blood spots was investigated under various conditions with or without heat stabilization at 95°C. Oseltamivir, cefotaxime and ribavirin were successfully stabilized by heating whereas significant losses were seen in unheated samples. Amodiaquine was stable with and without heating. Artemether and dihydroartemisinin were found to be very heat sensitive and began to decompose even at 60°C. Conclusion Heat stabilization is a viable technique to maintain analytes in blood spot samples, without the use of chemical additives, by stopping the enzymatic activity that causes sample degradation. PMID:23256470

VOLATILE LOSS AND CLASSIFICATION OF KUIPER BELT OBJECTS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Johnson, R. E.; Schmidt, C.; Oza, A.

Observations indicate that some of the largest Kuiper Belt Objects (KBOs) have retained volatiles in the gas phase (e.g., Pluto), while others have surface volatiles that might support a seasonal atmosphere (e.g., Eris). Since the presence of an atmosphere can affect their reflectance spectra and thermal balance, Schaller and Brown examined the role of volatile escape driven by solar heating of the surface. Guided by recent simulations, we estimate the loss of primordial N{sub 2} for several large KBOs, accounting for escape driven by UV/EUV heating of the upper atmosphere as well as by solar heating of the surface. Formore » the latter we present new simulations and for the former we scale recent detailed simulations of escape from Pluto using the energy limited escape model validated recently by molecular kinetic simulations. Unlike what has been assumed to date, we show that unless the N{sub 2} atmosphere is thin (<∼10{sup 18} N{sub 2} cm{sup −2}) and/or the radius small (<∼200–300 km), escape is primarily driven by the UV/EUV radiation absorbed in the upper atmosphere. This affects the discussion of the relationship between atmospheric loss and the observed surface properties for a number of the KBOs examined. Our long-term goal is to connect detailed atmospheric loss simulations with a model for volatile transport for individual KBOs.« less

An Improved Model of Heat-Induced Hyperalgesia—Repetitive Phasic Heat Pain Causing Primary Hyperalgesia to Heat and Secondary Hyperalgesia to Pinprick and Light Touch

PubMed Central

Henrich, Florian; Magerl, Walter; May, Arne

2014-01-01

This study tested a modified experimental model of heat-induced hyperalgesia, which improves the efficacy to induce primary and secondary hyperalgesia and the efficacy-to-safety ratio reducing the risk of tissue damage seen in other heat pain models. Quantitative sensory testing was done in eighteen healthy volunteers before and after repetitive heat pain stimuli (60 stimuli of 48°C for 6 s) to assess the impact of repetitive heat on somatosensory function in conditioned skin (primary hyperalgesia area) and in adjacent skin (secondary hyperalgesia area) as compared to an unconditioned mirror image control site. Additionally, areas of flare and secondary hyperalgesia were mapped, and time course of hyperalgesia determined. After repetitive heat pain conditioning we found significant primary hyperalgesia to heat, and primary and secondary hyperalgesia to pinprick and to light touch (dynamic mechanical allodynia). Acetaminophen (800 mg) reduced pain to heat or pinpricks only marginally by 11% and 8%, respectively (n.s.), and had no effect on heat hyperalgesia. In contrast, the areas of flare (−31%) and in particular of secondary hyperalgesia (−59%) as well as the magnitude of hyperalgesia (−59%) were significantly reduced (all p<0.001). Thus, repetitive heat pain induces significant peripheral sensitization (primary hyperalgesia to heat) and central sensitization (punctate hyperalgesia and dynamic mechanical allodynia). These findings are relevant to further studies using this model of experimental heat pain as it combines pronounced peripheral and central sensitization, which makes a convenient model for combined pharmacological testing of analgesia and anti-hyperalgesia mechanisms related to thermal and mechanical input. PMID:24911787

An experimental investigation devoted to determine heat transfer characteristics in a radiant ceiling heating system

NASA Astrophysics Data System (ADS)

Koca, Aliihsan; Acikgoz, Ozgen; Çebi, Alican; Çetin, Gürsel; Dalkilic, Ahmet Selim; Wongwises, Somchai

2018-02-01

Investigations on heated ceiling method can be considered as a new research area in comparison to the common wall heating-cooling and cooled ceiling methods. In this work, heat transfer characteristics of a heated radiant ceiling system was investigated experimentally. There were different configurations for a single room design in order to determine the convective and radiative heat transfer rates. Almost all details on the arrangement of the test chamber, hydraulic circuit and radiant panels, the measurement equipment and experimental method including uncertainty analysis were revealed in detail indicating specific international standards. Total heat transfer amount from the panels were calculated as the sum of radiation to the unheated surfaces, convection to the air, and conduction heat loss from the backside of the panels. Integral expression of the view factors was calculated by means of the numerical evaluations using Matlab code. By means of this experimental chamber, the radiative, convective and total heat-transfer coefficient values along with the heat flux values provided from the ceiling to the unheated surrounding surfaces have been calculated. Moreover, the details of 28 different experimental case study measurements from the experimental chamber including the convective, radiative and total heat flux, and heat output results are given in a Table for other researchers to validate their theoretical models and empirical correlations.

Interfacial heat transfer in multiphase molten pools with gas injection

NASA Astrophysics Data System (ADS)

Bilbao Y Leon, Rosa Marina

1998-12-01

In the very unlikely event of a severe reactor accident involving core meltdown and pressure vessel failure, it is vital to identify the circumstances that would allow the molten core material to cool down and resolidify, bringing core debris to a safe and stable state. In this type of accident, the molten material which escapes from the reactor pressure vessel will accumulate as a molten pool in the reactor cavity below. To achieve coolability of the corium in this configuration it has been proposed to flood the cavity with water from above forming a layered structure where upward heat loss from the molten pool to the water will cause the core material to quench and solidify. The effectiveness of this procedure depends largely on the rate of upward heat loss as well as on the formation and stability of an upper crust. In this situation the molten pool becomes a three phase mixture: the solid and liquid slurry formed by the molten pool cooled to a temperature below the temperature of liquidus, agitated by the gases formed in the concrete ablation process. The present work quantifies the partition of the heat losses upward and downward considering the influence of the solid fraction in the pool and the viscosity effects, and the rate of heat loss through a solid layer. To complete this task a intermediate scale experimental test section has been designed and built at the University of Wisconsin - Madison, in which simulant materials are used to model the process of heat and mass transfer which involves the molten pool, the solid layer atop and the coolant layer above. The design includes volumetric heating, gas injection from the bottom and solids within the pool. New experimental results showing the heat transfer behavior for pools with different viscosities and various solid fractions are presented. The current results indicate a power split which favors heat transfer upward to the coolant simulant above by a 2:1 or 3:1 ratio. In addition, the power split is

Cardiac response to whole-body heating

DOE Office of Scientific and Technical Information (OSTI.GOV)

Frey, M.A.B.; Kenney, R.A.

1979-04-01

Systolic time interval analysis was used to assess changes in ventricular function during heat stress. Seven subjects (4 M + 3 F, 22-35 yr) participated in the experiments. The heating procedure was the following: both legs of seated subjects were immersed to the knees in stirred water maintained at 42-45 C. The subjects' upper legs and trunks were enclosed in nonpermeable plastic and covered with a sheet blanket to reduce heat loss. After 30 min of heating, the water and plastic were removed. The parameters measured were HR and R-R interval, LVET, and PEP. Results were compared by t testmore » at the 0.05 significance level. The results pointed to a two-stage cardiac response to heat-vagal withdrawal followed by a strong sympathetic outflow to the heart affecting both inotropic and chronotropic characteristics.« less

Comparison of heat dissipation response between Malaysian and Japanese males during exercise in humid heat stress.

PubMed

Wakabayashi, Hitoshi; Wijayanto, Titis; Lee, Joo-Young; Hashiguchi, Nobuko; Saat, Mohamed; Tochihara, Yutaka

2011-07-01

This study investigated the differences in heat dissipation response to intense heat stress during exercise in hot and humid environments between tropical and temperate indigenes with matched physical characteristics. Ten Japanese (JP) and ten Malaysian (MY) males participated in this study. Subjects performed exercise for 60 min at 55% peak oxygen uptake in 32°C air with 70% relative humidity, followed by 30 min recovery. The increase in rectal temperature (T(re)) was smaller in MY during exercise compared to JP. The local sweat rate and total body mass loss were similar in both groups. Both skin blood flow and mean skin temperature was lower in MY compared to JP. A significantly greater increase in hand skin temperature was observed in MY during exercise, which is attributable to heat loss due to the greater surface area to mass ratio and large number of arteriovenous anastomoses. Also, the smaller increase in T(re) in MY may be explained by the presence of a significantly greater core-skin temperature gradient in MY than JP. The thermal gradient is also a major factor in increasing the convective heat transfer from core to skin as well as skin blood flow. It is concluded that the greater core-skin temperature gradient observed in MY is responsible for the smaller increase in T(re).

Energy-loss- and thickness-dependent contrast in atomic-scale electron energy-loss spectroscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tan, Haiyan; Zhu, Ye; Dwyer, Christian

2014-12-31

Atomic-scale elemental maps of materials acquired by core-loss inelastic electron scattering often exhibit an undesirable sensitivity to the unavoidable elastic scattering, making the maps counter-intuitive to interpret. Here, we present a systematic study that scrutinizes the energy-loss and sample-thickness dependence of atomic-scale elemental maps acquired using 100 keV incident electrons in a scanning transmission electron microscope. For single-crystal silicon, the balance between elastic and inelastic scattering means that maps generated from the near-threshold Si-L signal (energy loss of 99 eV) show no discernible contrast for a thickness of 0.5λ (λ is the electron mean-free path, here approximately 110 nm). Atmore » greater thicknesses we observe a counter-intuitive “negative” contrast. Only at much higher energy losses is an intuitive “positive” contrast gradually restored. Our quantitative analysis shows that the energy-loss at which a positive contrast is restored depends linearly on the sample thickness. This behavior is in very good agreement with our double-channeling inelastic scattering calculations. We test a recently-proposed experimental method to correct the core-loss inelastic scattering and restore an intuitive “positive” chemical contrast. The method is demonstrated to be reliable over a large range of energy losses and sample thicknesses. The corrected contrast for near-threshold maps is demonstrated to be (desirably) inversely proportional to sample thickness. As a result, implications for the interpretation of atomic-scale elemental maps are discussed.« less

Geothermal heating from Pinkerton Hot Springs at Colorado Timberline Academy, Durango, Colorado. Final technical report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Allen, C.C.; Allen, R.W.; Beldock, J.

1981-11-08

The efforts to establish a greater pool of knowledge in the field of low temperature heat transfer for the application of geothermal spring waters to space heating are described. A comprehensive set of heat loss experiments involving passive radiant heating panels is conducted and the results presented in an easily interpretable form. Among the conclusions are the facts that heating a 65 to 70 F/sup 0/ space with 90 to 100 F/sup 0/ liquids is a practical aim. The results are compared with the much lower rates published in the American Society of Heating Refrigeration and Air Conditioning Engineers SYSTEMS,more » 1976. A heat exchange chamber consisting of a 1000 gallon three compartment, insulated and buried tank is constructed and a control and pumping building erected over the tank. The tank is intended to handle the flow of geothermal waters from Pinkerton Hot Springs at 50 GPM prior to the wasting of the spring water at a disposal location. Approximately 375,000 Btu per hour should be available for heating assuming a 15 F/sup 0/ drop in water temperature. A combination of the panel heat loss experiments, construction of the heat exchange devices and ongoing collection of heat loss numbers adds to the knowledge available to engineers in sizing low temperature heat systems, useful in both solar and geothermal applications where source temperature may be often below 110 F/sup 0/.« less

Application of ultra-high-performance liquid chromatography coupled with LTQ-Orbitrap mass spectrometry for identification, confirmation and quantitation of illegal adulterated weight-loss drugs in plant dietary supplements.

PubMed

Cheng, Qiaoyuan; Shou, Linjun; Chen, Cen; Shi, Shi; Zhou, Minghao

2017-10-01

In this paper, an ultra-high-performance liquid chromatography coupled with linear ion trap quadrupole Orbitrap high resolution mass spectrometry (UHPLC-LTQ-Orbitrap HRMS) method was developed and validated for identification, confirmation and quantitation of illegal adulterated weight-loss drugs in plant dietary supplements. 13 wt-loss drugs were well separated by the gradient elution of 10mmol/L ammonium acetate - 0.05% formic acid H 2 O and acetonitrile at a flow rate of 0.2mL/min within 12min. The MS analysis was operated under the positive ion and in full MS/dd-MS 2 (data-dependent MS 2 ) mode. The full MS scan with resolution at 60 000 FWHM and narrow mass windows at 5ppm acquired data for identification and quantitation, and dd-MS 2 scan with resolution at 15 000 FWHM obtained product ions for confirmation. The method validation showed good linearity with coefficients of determination (r 2 ) higher than 0.9951 for all analytes. Meantime, all the LOD and LLOQ values were in the respective range of 0.3-2 and 1-9ng/g. The accuracy, intra- and inter-day precision were in the ranges of -1.7 to 3.4%, 1.7-5.0% and 1.9-4.4%, respectively. The mean recoveries ranged from 85.4 to 107.1%, while the absolute and relative matrix effect were in the corresponding range of 98.2-108.6% and 2.6-8.7%. Among 120 batches of weight loss plant dietary supplements, sibutramine and fluoxertine or both were positive in 29 samples. In general, LTQ-Orbitrap HRMS technology was a powerful tool for the analysis of illegal ingredients in dietary supplements. Copyright © 2017 Elsevier B.V. All rights reserved.

Quantitative description of human skin water dynamics by a disposition-decomposition analysis (DDA) of trans-epidermal water loss and epidermal capacitance.

PubMed

Rodrigues, Luis Monteiro; Pinto, Pedro Contreiras; Pereira, Luis Marcelo

2003-02-01

In vivo water assessment would greatly benefit from a dynamical approach since the evaluation of common related variables such as trans-epidermal water loss or "capacitance" measurements is always limited to instantaneous data. Mathematical modelling is still an attractive alternative already attempted with bi-exponential empirical models. A classical two-compartment interpretation of such models raises a number of questions about the underlying fundamentals, which can hardly be experimentally confirmed. However, in a system analysis sense, skin water dynamics may be approached as an ensemble of many factors, impossible to discretize, but conceptually grouped in terms of feasible properties of the system. The present paper explores the applicability of this strategy to the in vivo water dynamics assessment. From the plastic occlusion stress test (POST) skin water balance is assessed by modelling trans-epidermal water loss (TEWL) and "capacitance" data obtained at skin's surface. With system analysis (disposition-decomposition analysis) the distribution function, H(t), modelled as a sum of exponential terms, covers only the distribution characteristics of water molecules traversing the skin. This may correspond macroscopically to the experimental data accessed by "corneometry". Separately, the hyperbolic elimination function Q(TEWL) helps to characterise the dynamic aspects of water influx through the skin. In the observable range there seems to be a linear relationship between the net amount of water lost at the surface by evaporation, and the capability of the system to replenish that loss. This may be a specific characteristic of the system related to what may be described as the skin's "intrinsic hydration capacity" (IHC) a new functional parameter only identified by this strategy. These new quantitative tools are expected to find different applicabilities (from the in vivo skin characterisation to efficacy testing) contributing to disclose the dynamical nature

Mass loss in red giants and supergiants