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1

Frost heave susceptibility of saturated soil under constant rate of freezing  

Energy Technology Data Exchange (ETDEWEB)

Introduced are the results of experiments carried out to quantitatively obtain the frost heave pressure and displacement of soil subjected to artificial freezing or freezing around in-ground liquefied natural gas storage tanks. This experiment is conducted to evaluate the frost heave susceptibility of saturated soil under overconsolidation. In other words, this experiment was carried out to obtain the relation of the over-burden pressure and freezing rate to the frost heave ratio by observing the frost heave displacement and freezing time of specimens by freezing the specimens at a constant freezing rate under a constant overburden pressure, while letting water freely flow in and out of the system. Introduced are the procedures for frost heave test required to quantitatively obtain the frost heave displacement and pressure of soil. Furthermore, the relation between the frost heave susceptibility and physical properties of soil obtained by this test is reported.

Ryokai, K.; Iguro, M.; Yoneyama, K.

1982-01-01

2

Molecular polarizabilities and susceptibilities from Frost-model wavefunctions  

International Nuclear Information System (INIS)

Average polarizabilities and susceptibilities of a number of molecules are computed from Frost-model wavefunctions using a form of symmetry-adapted double perturbation theory. The anisotropy of ? and chi is found for a few molecules using the elliptical Gaussian form of the Frost model. The results obtained are in reasonable agreement with experiment and other calculated values

1975-12-01

3

Experimental study of frost heaving of saturated soil  

Energy Technology Data Exchange (ETDEWEB)

This papaer reports on a comparison of results of frost heaving experiment using X-ray and result of simulation by means of a frost heaving analysis wherein a water flow and a heat flow were connected. In the experiment, by lowering the temperature of the top and bottom cooling plates, temperature gradient in the sample and freezing rate was maintained constant. It was found that the water-absorption rate increased linearly with the increase of temperature gradient in the frozen soil. It was also found, by measuring the displacement of the lead beads, that the growth of the frost heaving was due to the growth of an ice lens nearest to the 0/sup 0/C line. Rate of heaving increased as the freezing line progresses reducing the length of the unfrozen portion. In connection with the result of experiment, a simulation was made with an analysis model on the basis of Miller's frost heave theory (1978). Calculated results on the frost heaving speed coincided with the observation which increased as the frost line make a progress. (13 figs, 4 tabs, 9 refs)

Ishizaki, Takeshi; Nishio, Nobuaki

1988-03-25

4

Model experiment of frost heave and thawing settlement of artificially frozen soils  

Energy Technology Data Exchange (ETDEWEB)

Based on analysing the differences between artificially frozen soils and naturally frozen soils and comparing the present testing devices for the study of frost heave and thawing settlement at home and abroad, a new device for studying the frost heave and thawing settlement of artificially frozen soil was developed. This device has been applied to test the frost heave and thawing settlement of clay often seen in Xuzhou, and the result proves that it is reliable and useful. Meanwhile, some conclusions such as the frost heave in vertical direction is much smaller than the thawing settlement in the same direction have been drawn. 6 refs., 3 figs.

Wang, J.; Wang, W.; Shi, T. [China University of Mining and Technology, Xuzhou (China). College of Architecture and Civil Engineering

1999-07-01

5

Modelling Frost Heaving and Frost Penetration in Soils at Some Observation Sites in Finland: The SSR Model.  

Science.gov (United States)

The purpose of the study was to monitor frost heaving and frost penetration at six observation sites in Finland in 1982 - 1984. Frost heaving was also studied in the laboratory with frost-heave tests carried out on undisturbed specimens. A calculation mod...

S. Saarelainen

1992-01-01

6

Severe soil frost reduces losses of carbon and nitrogen from the forest floor during simulated snowmelt: A laboratory experiment  

UK PubMed Central (United Kingdom)

Considerable progress has been made in understanding the impacts of soil frost on carbon (C) and nitrogen (N) cycling, but the effects of soil frost on C and N fluxes during snowmelt remain poorly understood. We conducted a laboratory experiment to determine the effects of soil frost on C and N fluxes from forest floor soils during snowmelt. Soil cores were collected from a sugar maple (Acer saccharum)–American beech (Fagus grandifolia) and a red spruce (Picea rubens)–balsam fir (Abies balsamea) forest at the Hubbard Brook Experimental Forest in New Hampshire, U.S.A. Soils were exposed to one of three temperature treatments, including severe (?15 °C), mild (?0.5 °C), and no soil frost (+5 °C) conditions. After one week the soils were incubated at +5 °C and snow was placed on top of the soils to simulate spring snowmelt. NO3? losses were up to 5.5 mg N kg?1 soil greater in the mild soil frost treatment than the severe soil frost treatment. Net losses of NH4+ and DON in leachate were up to 19 and 18 mg N kg?1 soil greater in the no soil frost and mild soil frost treatments, respectively, than the severe soil frost treatment. In contrast, soil frost did not have a significant impact on dissolved organic C or cumulative gaseous fluxes of C and N throughout the snowmelt period. However, the total cumulative flux of C (i.e. dissolved organic C + CO2 + CH4) and N (i.e. dissolved organic N + NH4 + NO3 + N2O) in the severe soil frost treatment were between one quarter and one half that observed in the no soil frost treatment for both forest types. Together, the results of this study show that total fluxes of N in leachate, as well as total cumulative C and N fluxes (gases + leachate), were significantly reduced following severe soil frost. We conclude that the extent to which C and N cycling during snowmelt is altered in response to changes in winter climate depend on both the presence and severity of soil frost.

Reinmann AB; Templer PH; Campbell JL

2012-01-01

7

Impacts of a water stress followed by an early frost event on beech (Fagus sylvatica L.) susceptibility to Scolytine ambrosia beetles - Research strategy and first results  

Science.gov (United States)

Climate change tends to induce more frequent abiotic and biotic extreme events, having large impacts on tree vitality. Weakened trees are then more susceptible to secondary insect outbreaks, as it happened in Belgium in the early 2000s: after an early frost event, secondary Scolytine ambrosia beetles attacks were observed on beech trees. In this study, we test if a combination of stress, i.e. a soil water deficit preceding an early frost, could render trees more attractive to beetles. An experimental study was set in autumn 2008. Two parcels of a beech forest were covered with plastic tents to induce a water stress by rain interception. The parcels were surrounded by 2-meters depth trenches to avoid water supply by streaming. Soil water content and different indicators of tree water use (sap flow, predawn leaf water potential, tree radial growth) were followed. In autumn 2010, artificial frost injuries will be inflicted to trees using dry ice. Trees attractivity for Scolytine insects, and the success of insect colonization will then be studied. The poster will focus on experiment setting and first results (impacts of soil water deficit on trees).

La Spina, Sylvie; de Cannière, Charles; Molenberg, Jean-Marc; Vincke, Caroline; Deman, Déborah; Grégoire, Jean-Claude

2010-05-01

8

Two-dimensional model of coupled heat and moisture transport in frost-heaving soils  

International Nuclear Information System (INIS)

A two-dimensional model of coupled heat and moisture flow in frost-heaving soils is developed based upon well known equations of heat and moisture flow in soils. Numerical solution is by the nodal domain integration method which includes the integrated finite difference and the Galerkin finite element methods. Solution of the phase change process is approximated by an isothermal approach and phenomenological equations are assumed for processes occurring in freezing or thawing zones. The model has been verified against experimental one-dimensional freezing soil column data and experimental two-dimensional soil thawing tank data as well as two-dimensional soil seepage data. The model has been applied to several simple but useful field problems such as roadway embankment freezing and frost heaving

1984-01-01

9

Frost-susceptible protein in plasma membranes in tubers of Helianthus tuberosus L.  

UK PubMed Central (United Kingdom)

When plasma membranes were prepared from tubers of Helianthus tuberosus L. (Jerusalem artichoke) frozen at a sublethal temperature (-10 degrees C), the levels of some plasma membrane proteins, named frost-susceptible proteins (FSPs), decreased [Uemura, M., et al., Plant Physiol., 80, 187-195 (1986)]. The aim of this study was to characterize the response of FSP120, which is named FSP-3 in a previous report, to freezing treatment by immunoblotting. Levels of FSP120 in the plasma membranes of tubers decreased after sublethal freezing, whereas no degraded products were detected in the microsomes or the soluble fraction. The amount of FSP120 in the crude extract of frozen tubers remained at a comparable level to that of the unfrozen tubers. These results suggest that FSP120 might be released from plasma membranes during freezing treatment of the tubers of Jerusalem artichoke.

Arakawa K; Hanazaki M; Yoshida S

2004-01-01

10

Frost-susceptible protein in plasma membranes in tubers of Helianthus tuberosus L.  

Science.gov (United States)

When plasma membranes were prepared from tubers of Helianthus tuberosus L. (Jerusalem artichoke) frozen at a sublethal temperature (-10 degrees C), the levels of some plasma membrane proteins, named frost-susceptible proteins (FSPs), decreased [Uemura, M., et al., Plant Physiol., 80, 187-195 (1986)]. The aim of this study was to characterize the response of FSP120, which is named FSP-3 in a previous report, to freezing treatment by immunoblotting. Levels of FSP120 in the plasma membranes of tubers decreased after sublethal freezing, whereas no degraded products were detected in the microsomes or the soluble fraction. The amount of FSP120 in the crude extract of frozen tubers remained at a comparable level to that of the unfrozen tubers. These results suggest that FSP120 might be released from plasma membranes during freezing treatment of the tubers of Jerusalem artichoke. PMID:14745181

Arakawa, Keita; Hanazaki, Mitsuru; Yoshida, Shizuo

2004-01-01

11

Effects of freezing on soil temperature, frost propagation and moisture redistribution in peat: laboratory investigations  

Directory of Open Access Journals (Sweden)

Full Text Available The effects of freezing on soil temperature and water movement were monitored in four peat Mesocosms subjected to bidirectional freezing. Temperature gradients were applied by bringing the Mesocosm tops in contact with sub-zero air temperature while maintaining a continuously frozen layer at the bottom (proxy permafrost). Soil water movement towards the freezing front (from warmer to colder regions) was inferred from soil freezing curves and from the total water content of frozen core samples collected at the end of freezing cycle. This study illustrates how differences in initial water content influence the hydrologic functions of active layer in permafrost terrains covered with thick peat during soil freezing. A substantial amount of water, enough to raise the upper surface of frozen saturated soil within 15 cm of the soil surface at the end of freezing period, appeared to have moved upwards during freezing. Effects of temperature on soil matric potential, at least in the initial freezing period, appear to drive such movement as seen from analysis of soil freezing curves. Vapour movement from warmer to colder regions also appears to contribute in moisture movement. Frost propagation is controlled by latent heat for a long time during freezing. A simple conceptual model describing freezing of an organic active layer initially resembling a variable moisture landscape is proposed based upon the results of this study. The results of this study will help in understanding, and ultimately forecasting, the hydrologic response of wetland-dominated terrain underlain by discontinuous permafrost.

R. M. Nagare; R. A. Schincariol; W. L. Quinton; M. Hayashi

2011-01-01

12

Effect of Soil Frost on Snow-melt runoff Generation: Stable Isotope Study in Drained Peatlands  

Science.gov (United States)

In this study, we analysed stable isotopes and water quality of runoff water collected daily from two different peatland drainage areas with automated samplers from March 2012 to October 2012, located in Northern Finland. In addition we collected weekly snow samples for stable isotope analysis. Our primary aim was to find out how different land use types, i) peat extraction area and ii) peatland forestry, are affecting the flow paths and runoff water quality during the snow melt period. Results show that there is a clear difference in ?O18 signal between these systems. The peatland forestry area is located at groundwater dominated area which can be seen as a flat line when ?O18 values of all samples are plotted. Samples taken at the peat extraction area show a clear response to the snowmelt event. Most likely this difference is caused by different soil frost conditions. Quantity of the groundwater at the forestry area prevents the soil from freezing during winter, therefore water originating from melting snow is able to infiltrate to the peat soil and push pre-event water into the drainage system. This observation is also visible in water quality of runoff water as high peak in colour during the snow melt period. Contrary, the peat extraction area behaves in opposite way. Melting water from snow is not able to infiltrate to ditches but instead will rapidly move on the frozen soil surface as a Hortonian overland flow. Because the soil is frozen, moving water is not able to leach humic substances from soil layers or erode particulate matter from the soil surface. These observations can be used to develop water quality protection policies for drained peatland areas. In Northern areas, where freezing of soil during winter is common it is not crucial to emphasize water protection during spring snowmelt, as frozen soil helps to maintain the runoff water quality at reasonable levels. In the areas where ground frost is rarer the impact of purifying runoff water in spring thaw will be more beneficial for the receiving water bodies.

Eskelinen, Riku; Ronkanen, Anna-Kaisa; Marttila, Hannu; Kløve, Bjørn

2013-04-01

13

A preliminary synoptic assessment of soil frost on Marion Island and the possible consequences of climate change in a maritime sub-Antarctic environment  

Directory of Open Access Journals (Sweden)

Full Text Available Located in the sub-Antarctic, Marion Island (46° 54? S, 37° 45? E) has a distinct periglacial environment that is sensitive to climate change. Diurnal soil frost is the most important geomorphic process occurring on the island and this paper aims to understand the synoptic weather circulation pattern associated with summer soil frost occurrence in a sub-Antarctic environment. Preliminary results from automated microclimate measurements in the interior of Marion Island show that summer soil frost is dependent on Antarctic air mass circulation. This occurs exclusively during post-cyclonic airflow after the passage of a cold front connected to a mid-latitudinal cyclone and subsequent ridging in of the South Atlantic Anticyclone behind the cold front, or when a series of low pressure systems passes over the island. The duration and intensity of soil frost cycles are dependent on the duration of post-cyclonic Antarctic air mass circulation. Summer soil frost on Marion Island is driven by a complex interaction between the latitudinal position of the passing cyclone, the latitudinal position of the ridging anticyclone as well as the trajectory of the air mass circulation. The data suggest that predicted trends in synoptic climate change in the sub-Antarctic may lead to non-linear responses in soil frost dynamics.

Werner Nel

2012-01-01

14

Water relation response to soil chilling of six olive (Olea europaea L.) cultivars with different frost resistance  

Energy Technology Data Exchange (ETDEWEB)

The relationship between the water relations of six olive cultivars exposed to different soil temperatures (14 0.1, 9.9 0.1 and 5.8 0.2 degree centigrade) and their inherent frost resistance (as determined by two different methods) was investigated. Soil chilling was achieved by introducing pots of olive plants into water baths. The water relations of these plants were compared to those of plants kept under conditions of room temperature. The cultivars Frantoio, Picual and Changlot Real began to show significant dehydration below 14 degree centigrade, while Cornicabra, Arbequina and Ascolana Tenera showed this below 10 degree centigrade. This response is probably due to delayed stomatal closure. Only Cornicabra and Picual showed a significant reduction in leaf conductance (below 10 degree centigrade and 6 degree centigrade respectively). This absence of stomatal control led to a significantly greater dehydration in Ascolana Tenera. These variations in response to the soil chilling temperature suggest that different mechanisms may be at work, and indicate that would be necessary to study the influence of rootstock in the frost resistance of olive plants. The variations recorded grouped the cultivars as either resistant (Cornicabra), tolerant (Picual, Ascolana Tenera and Arbequina), or sensitive (Frantoio and Changlot Real). This classification is in line with the frost resistance reported for these cultivars in the literature, and with the results obtained in the present work using the stomatal density and ion leakage methods of determining such resistance. (Author) 40 refs.

Perez-Lopez, D.; Gijon, M. C.; Marino, J.; Moriana, A.

2010-07-01

15

Soil stabilization and frost heave prevention for volcanic cohesive soil of low water content by lime and cement; Teigansui hi kazanbaishitsu nenseido no sekkai oyobi cemento ni yoru doshitsu antei shori to togai boshi  

Energy Technology Data Exchange (ETDEWEB)

In cold districts, frost heave of ground in the winter and ground softening in the ice-melting period in the spring are problems. Volcanic cohesive soil is a soil liable to frost heave, and many frost heave damages occurred in ground of cohesive soil of low water content. However, it is considered that it is effective to use slaked lime and cement as well as raw lime which has been conventionally used for soil stabilization and frost heave protection of volcanic cohesive soil of low water content (natural water content 60% or less). This paper describes the results of the comparison and study on the application of raw lime, slaked lime, and cement as soil stabilizers to the cohesive soil of low water content. The results led to many new findings that if the non-immersion strength of the soil stabilized by lime and cement is known, the immersion strength can be estimated, that the water content has an effect on frost heave more than the immersion strength, and that the relationships between the water content and the frost heave amount of the three types of soil stabilizers are expressed by a single straight line, showing a similar tendency. 7 refs., 12 figs.

Ishida, H. [Iwate Univ., Iwate (Japan). Faculty of Engineering

1995-08-01

16

Frost heaving of planted tree seedlings in the boreal forest of northern Sweden  

International Nuclear Information System (INIS)

Frost heaving can be a leading cause of tree seedling mortality in many places in the boreal forest of Northern Sweden. The aim of this investigation was to improve our understanding of frost heaving of planted tree seedlings as related to snow cover, scarification, planting methods and soil types. The thesis is based on a review paper, three field experiments and one laboratory experiment. The experiments focus on different methods to control frost heaving of forest tree seedlings and on a number of factors affecting the extent of frost heaving. The review paper identifies the many aspects of frost heaving of forest tree seedlings and agricultural crops based on an intensive review of the research contributions made during the last century. Even if many investigations have been carried out with the aim to decrease the extent of frost heaving, very little quantitative results are available for tree seedlings. In a field experiment, the choice of planting positions was effective in decreasing frost heaving of planted seedlings following mounding or disc-trenching. Seedlings planted in the depressions were largely affected by frost heaving with a maximal vertical displacement of 5.4 cm while frost heaving did not occur on the top of the mound. On the other hand, the planting time and planting depth had no influence on the extent of frost heaving. In another field experiment the size of the scarified patches was strongly correlated to frost heaving which reached between 7.6 and 11.5 cm in 4 and 8-dm patches compared to between 4.4 and 5.3 in non-scarified soil and in a 1-dm patch. Ground vegetation probably decreases the diurnal temperature variation and the number of freezing-thawing cycles. The duration and magnitude of frost temperatures, the frost hour sum, increased with patch size. The difference between the 8-dm and 1-dm patch increased to 2064 hour-degrees at the end of the winter. In larger patches, the planting depth seemed to be effective in reducing the maximum frost heaving of the seedlings. In the third field experiment snow cover also showed to be an important factor in regard to frost heaving of tree seedlings. In a snow-free treatment combined with soil scarification, an uplift of 14.6 cm was measured during a winter season. In contrast no vertical displacement was observed under a simulated snow cover. The strong influence of snow on the extent of frost heaving indicates that further investigation should be focused on the interaction between maximum frost heaving and snow depth. In the laboratory freezing chamber experiment it was demonstrated that soil from spodic B horizon is less susceptible to frost heaving than soil from E horizon. Needle ice did not grow at all on soil samples from E horizon during a 3-day test, neither on fresh, nor on oven dried samples. On fresh samples of soil from Bs horizon, needle ices reached a maximum height of 9.7 cm in average. The use of theodolite and wooden dowels to estimate the extent of frost heaving in this study allowed to follow the process during the frost heaving period. A vertical uplift in millimetres could be recorded. A development of reliable measuring methods which allow a continuous estimation of the extent of frost heaving damage during the whole process, would undoubtedly represent an important step towards a better understanding of frost heaving of tree seedlings

2000-01-01

17

Frost heaving of planted tree seedlings in the boreal forest of northern Sweden  

Energy Technology Data Exchange (ETDEWEB)

Frost heaving can be a leading cause of tree seedling mortality in many places in the boreal forest of Northern Sweden. The aim of this investigation was to improve our understanding of frost heaving of planted tree seedlings as related to snow cover, scarification, planting methods and soil types. The thesis is based on a review paper, three field experiments and one laboratory experiment. The experiments focus on different methods to control frost heaving of forest tree seedlings and on a number of factors affecting the extent of frost heaving. The review paper identifies the many aspects of frost heaving of forest tree seedlings and agricultural crops based on an intensive review of the research contributions made during the last century. Even if many investigations have been carried out with the aim to decrease the extent of frost heaving, very little quantitative results are available for tree seedlings. In a field experiment, the choice of planting positions was effective in decreasing frost heaving of planted seedlings following mounding or disc-trenching. Seedlings planted in the depressions were largely affected by frost heaving with a maximal vertical displacement of 5.4 cm while frost heaving did not occur on the top of the mound. On the other hand, the planting time and planting depth had no influence on the extent of frost heaving. In another field experiment the size of the scarified patches was strongly correlated to frost heaving which reached between 7.6 and 11.5 cm in 4 and 8-dm patches compared to between 4.4 and 5.3 in non-scarified soil and in a 1-dm patch. Ground vegetation probably decreases the diurnal temperature variation and the number of freezing-thawing cycles. The duration and magnitude of frost temperatures, the frost hour sum, increased with patch size. The difference between the 8-dm and 1-dm patch increased to 2064 hour-degrees at the end of the winter. In larger patches, the planting depth seemed to be effective in reducing the maximum frost heaving of the seedlings. In the third field experiment snow cover also showed to be an important factor in regard to frost heaving of tree seedlings. In a snow-free treatment combined with soil scarification, an uplift of 14.6 cm was measured during a winter season. In contrast no vertical displacement was observed under a simulated snow cover. The strong influence of snow on the extent of frost heaving indicates that further investigation should be focused on the interaction between maximum frost heaving and snow depth. In the laboratory freezing chamber experiment it was demonstrated that soil from spodic B horizon is less susceptible to frost heaving than soil from E horizon. Needle ice did not grow at all on soil samples from E horizon during a 3-day test, neither on fresh, nor on oven dried samples. On fresh samples of soil from Bs horizon, needle ices reached a maximum height of 9.7 cm in average. The use of theodolite and wooden dowels to estimate the extent of frost heaving in this study allowed to follow the process during the frost heaving period. A vertical uplift in millimetres could be recorded. A development of reliable measuring methods which allow a continuous estimation of the extent of frost heaving damage during the whole process, would undoubtedly represent an important step towards a better understanding of frost heaving of tree seedlings.

Goulet, France

2000-07-01

18

Frost phenomena on Mars.  

UK PubMed Central (United Kingdom)

The hypothesis that the Martian wave of darkening might be a frostheaving phenomenon has been examined. Consideration of the water-vapor sorption characteristics of a silicate mineral surface at temperatures below freezing leads to the conclusion that, without strongly deliquescent salts to attract and retain liquid water in the Martian soil, frost-heaving phenomena are not to be expected on Mars. On the other hand frost-heaving phenomena involving the freezing and thawing of ammonia may be common in the soils of Jupiter.

Anderson DM; Gaffney ES; Low PF

1967-01-01

19

A preliminary synoptic assessment of soil frost on Marion Island and the possible consequences of climate change in a maritime sub-Antarctic environment  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Located in the sub-Antarctic, Marion Island (46° 54? S, 37° 45? E) has a distinct periglacial environment that is sensitive to climate change. Diurnal soil frost is the most important geomorphic process occurring on the island and this paper aims to understand the synopti...

Werner Nel

20

Frost resistance in Salix  

Energy Technology Data Exchange (ETDEWEB)

This thesis presents results from a series of studies in various aspects of frost hardiness in Salix viminalis and Salix dasyclados. The seasonal development of frost resistance and the processes which lead to frost damage under different environmental and laboratory test conditions are elucidated, and current methods to evaluate plant response to temperature stress are developed further. A number of phases in the seasonal development of frost resistance can be distinguished, in which the susceptibility of plants to frost ranges from low (dormant stage) to high (growth stage). Changes in phenological characters, ultrastructural cell features, activity of the vascular cambium and storage products (starch, proteins) are correlated with the changes in frost resistance during the annual growth cycle. Differences in relative growth rates imposed by nutrient conditions also affected onset time and rate of frost hardiness development and deacclimation and onset of growth during spring. Dormant stem cutting of various Salix species and clones collected outdoors during winter or subjected to a standardized artificial hardening regime at -4 degrees C survived exposure to at least 85 degrees C. The presence of ice on wintering shoots will restrict freezing avoidance of shoot to above -4 degrees C. Early formation of extracellular ice at -1 degrees C to -4 degrees C, followed by associated high tolerance to freeze-induced dehydration, was concluded to be an important survival mechanism for all winter-dormant Salix plant. Salix species have the inherent ability to develop adequate tolerance to the low winter temperatures in Scandinavian conditions. 304 refs, 8 figs, 11 tabs

Fircks, H.A. von

1994-12-31

 
 
 
 
21

Investigation of effects of moisture on soil temperature regimes and frost depth in a laboratory model  

Directory of Open Access Journals (Sweden)

Full Text Available Freezing depth is one the most important climatic parameters for indices applied in various fields such as agriculture and civil engineering. The parameter of freezing depth depends on different factors including astronomical, surface air temperature, humidity; soil characteristics such as texture, heat capacity, thermal conductivity and specific heat. This study investigated the effect of air temperature on freezing depth. Apparatus able to reach temperatures of -16 ?C was set up to test soil freezing points. To measure and record soil temperature at depths of 10, 20, 50, and 70 cm, an automatic measurement system was designed. The system’s sensors included an electronic thermostat, inserted at various different soil depths. Variations of temperature measured by the sensors were transferred to a transformer and these measurements were then transferred to a computer as binary codes. These codes were then processed by a computer program and converted to a numerical format. After calibration, several experiments were conducted using soil bins of different textures including clay, clay-sand and sand, at percentage moisture contents of 0, 10, and 15%. Results of tests showed that freezing depth of soil in a dry state (0% moisture content) for soil with smaller pores (such as clay) was less than that of soil with larger pores (such as sand). The advancing speed of the freezing front had a similar trend. By increasing soil moisture (0% to 10%), for all soil samples, the depth of freezing and the advancing speed of the freezing front increased. This condition was more pronounced in soil with finer texture than in soil with coarser texture. By increasing the amount of soil moisture content, clay soil maintained its moisture throughout depth, but in sandy and clay-sandy soil, the moisture content decreased from the top to the bottom (due to drainage). This phenomenon affected the advancing speed of the freezing front in these soil samples. Finally, the correlation between the time of soil freezing (t), and the temperature at different depths during the freezing process (T), was investigated, and it was concluded that this can be written in the form of{ }, significant at 1% level for all three types of soil.

Rahnama Yami E. et al.

2012-01-01

22

Susceptibility of ectomycorrhizal fungi to soil heating.  

UK PubMed Central (United Kingdom)

Ectomycorrhizal (EcM) fungi are an important biotic factor for successful tree recruitment because they enhance plant growth and alleviate drought stress of their hosts. Thus, EcM propagules are expected to be a key factor for forest regeneration after major disturbance events such as stand-replacing forest fires. Yet the susceptibility of soil-borne EcM fungi to heat is unclear. In this study, we investigated the heat tolerance of EcM fungi of Scots pine (Pinus sylvestris L., Pinaceae). Soil samples of three soil depths were heated to the temperature of 45, 60 and 70 °C, respectively, and surviving EcM fungi were assessed by a bioassay using Scots pine as an experimental host plant. EcM species were identified by a combination of morphotyping and sequencing of the ITS region. We found that mean number of species per sample was reduced by the 60 and 70 °C treatment, but not by the 45 °C treatment. Species composition changed due to heat. While some EcM fungi species did not survive heating, the majority of species was also found in the heated samples. The most frequent species in the heat treatment were Rhizopogon roseolus, Cenococcum geophilum and several unidentified species.

Kipfer T; Egli S; Ghazoul J; Moser B; Wohlgemuth T

2010-05-01

23

Orchard floor management utilizing soil-applied coal dust for frost protection. Part II. Seasonal microclimate effect  

Energy Technology Data Exchange (ETDEWEB)

Orchard floor management has been found to affect the microclimate on radiation frost nights; however, long-term effects of management on the seasonal microclimate have not been studied. Comparisons were made of microclimatic factors in the spring of 1986 between two adjacent 1.4 ha peach (Prunus persica (L.) Batsch) plots in the Shenandoah Valley of West Virginia. The orchard floor of one plot has grass maintained in both the 3-m-wide tree row and 3-m-wide grass alley (grass plot); the floor of the other plot was similar except that coal dust was applied to the soil surface of the tree row (coal dust plot). Net radiative (R/sub n/), soil heat (G), and sensible heat flux were greater during the daytime in the coal dust plot. Averaged over the 55-day period of this study, the daily R/sub n/ and G was 7 and 2 W m/sup -2/ greater in the coal dust plot, respectively. Thus, G accounted for 30% of R/sub n/ on a daily basis. Daily average tree-row air (to 195 cm) and soil (to 5 cm) temperatures were approx. 0.2 and 2.5 degrees C higher, respectively, in the coal dust plot. The cumulative differences found at the end of this study indicated that the coal dust plot absorbed 32 MJ more net radiant energy than the grass plot. Cumulative G differences accounted for 9 MJ (30%) of the R/sub n/ difference, with a greater heat flux into the soil in the coal dust plot. An approximate difference of 130 growing-degree-hours (GDH), which represented a 1% difference, was found at the end of the study. However, at the time of bloom, which required 4000 GDH, only a 40 GDH difference was found. These results indicate that microclimatic differences between management systems are cumulative and that differences for the site studied can develop by late spring. In years with greater cloud-free days, even larger microclimatic differences could develop than those reported in this study. 8 refs., 2 figs., 1 tab.

Sharratt, B.S.; Glenn, D.M.

1988-07-01

24

Modeling soil magnetic susceptibility and frequency-dependent susceptibility to aid landmine clearance.  

Science.gov (United States)

Information on the electromagnetic properties of soils and their effects on metal detectors is increasingly necessary for effective demining due to limited detector efficacy in highly magnetic soils and the difficulty of detecting minimummetal mines. Magnetic measurements of soils, such as magnetic susceptibility and frequency dependent susceptibility can aid the detection of problem soils, but are not part of standard soil analyses. Consequently, little information about soil magnetism exists within the soil, environmental science and environmental geophysics communities. Lack of empirical data may be compensated through the estimation of soil magnetic characteristics by predictive modeling approaches. Initial modeling of soil types in Bosnia and Herzegovina (BiH) was attempted by expert and analogue approaches, using only coarse scale soil type information, which resulted in the production of national soil maps for low field and frequency-dependent susceptibility. Validation of the maps was achieved by comparison of empirical magnetic data from soil samples in the National Bosnian soil archive in Sarajevo. Discrepancies between the model and empirical data are explained in part by the differences in soil parent material within each soil type, which controls the amount of Fe released into the soil system available for in situ conversion to magnetic Fe oxides. The integration of soil information (type and parent material), expert knowledge and empirical data refines the predictive modeling of soil magnetic characteristics in temperate-Mediterranean environments such as BiH. Further spatial separation of soil types in the landscape can be achieved by digital terrain modeling. Preliminary fine-scale, landscape-soil modeling indicates improved spatial resolution of soil types compared with the original coarsely-mapped soil units, and the potential to synthesize local scale soil magnetic maps.

Hannam, Jacqueline A.; Dearing, John A.

2006-06-01

25

Geostatistical 3-dimensional integration of measurements of soil magnetic susceptibility  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In soil magnetometry, two types of measurements are usually performed. The first type is measurements performed on the soil surface, frequently using an MS2D sensor. The second type includes measurements of magnetic susceptibility carried out in the soil profile, usually to a depth of about 30 cm. U...

Zawadzki, Jaros?aw; Magiera, Tadeusz; Fabija?czyk, Piotr; Kusza, Grzegorz

26

Additional requirements for protective filtering materials of closed drainage laying in the seasonal soil frost zone  

Directory of Open Access Journals (Sweden)

Full Text Available The paper considers the problem of preserving the filtration properties of the drainage material in the zone of seasonal freezing. Studies have shown that drainage can lay in the zone of seasonal freezing, but the pores in the filter should not be completely filled with ice. The drainage filter may include a geotextile.The article introduces the filtration model, taking into account the freezing of water in the geotextile. The model analysis allows obtaining conclusions about changes in the porosity and the coefficient of filtration of geotextile with according to changes in ice content. The diameter of the geotextile fiber, the initial porosity and the experimentally determined water loss geotextiles are considered. The formulas relating these parameters are found.The results can be applied for the selection of geotextiles used in the zone of seasonal freezing for the drainage protection or as separating filter layers in the soil.

V.I. Shtykov; A.B. Ponomarev

2012-01-01

27

On the significance of frost phenomena with the 'novel' forest damages  

Energy Technology Data Exchange (ETDEWEB)

The impact of well-known air pollutants and of atmospheric deposition on the forests in the Federal Republic of Germany, as well as the site conditions and the susceptibility of the affected species with regard to pollutants, vary considerably. Therefore the 'novel' diseases probably are synchronized by factors other than pollution, acting rather uniformly over large areas. Weather stress phenomena inducing widespread frost damages on a large scale are causes that have to be taken primarily into consideration. This assumption is supported by the fact, that the 'novel' diseases are most serious at higher elevations of the mountainous regions, where frost is an important limiting factor for the vegetation even under natural conditions. In the literature many reports are available proving that frost is capable to induce serious defoliation and crown transparency. There is some evidence that frost phenomena and frost damage were unusually frequent in the period from 1979-1987. Field observations and experimental results clearly demonstrate synergistic interactions between frost and other stresses like pollution (SO/sub 2/, O/sub 3/), unbalanced or insufficient nutrition, or attack of pathogens. There are physiological explanations for part of these interactions. Therefore, it is the assumption that an unusual sequence of large-scale frost phenomena was acting as important synchronizer, triggering, the occurrence of symptoms characteristic for the 'novel' diseases and determining the progress of this disease remarkbly. Soil conditions and pollution as well as atmospheric deposition on the other hand are assumed to be local or regional predisposing factors.

Bosch, C.; Rehfuess, K.E.

1988-05-01

28

Magnetic susceptibility mapping of soil pollution  

International Nuclear Information System (INIS)

Fast and cost-effective detection of industrial pollution can significantly promote its ecological, economic and social assesment. A magnetometric method, used for qualitative determination of anthropogenic contamination, meets these requirements but needs further development in more quantitative terms.lt could be used successfully in numerous cases when heavy metals coexists with strongly magnetic iron oxide particles in the source dust. We presented a magnetic study which examines the utility of magnetometric techniques for rapid, qualitative detection of metallic pollutants in soils. In the present paper we tested the use of rock-magnetic method designed to access the degree of pollution of soil taken from Novaky situated in the south-western of Slovakia. The aim was to identify magnetic particles and to link magnetic pollution, to trace distribution and concentration of contaminants in soil. About 40 years the rainwater overflow the dump and flooded out the ash waste from the brown coal power plant in Novaky. Soil samples have been taken from 3 horizons (20, 40 and 60 cm) and measured by KLY-kappabridge in the Slovak Academy of Sciences, in Geophysical Institute in Bratislava. Our results clearly demonstrate that magnetic anomalies can be explained by human activity. (authors)

2006-01-01

29

Frost resistance and susceptibility to ice formation during natural hardening in relation to leaf anatomy in three evergreen tree species from New Zealand.  

UK PubMed Central (United Kingdom)

Foliar frost resistance of three endemic New Zealand land trees, Nothofagus menziesii (Hook. f.) Oerst. (Fagaceae), Pittosporum eugenioides A. Cunn. (Pittosporaceae) and Griselinia littoralis Forst. f. (Cornaceae), was examined as the trees hardened from late summer to midwinter in a lowland forest site. The lowest temperatures causing 50% damage (LT(50)) occurred in late winter and were similar to those recorded for other forest trees native to New Zealand (-11.7 degrees C in N. menziesii, -10.7 degrees C in P. eugenioides, and -10.6 degrees C in G. littoralis). All three species hardened by 4-7 degrees C, with G. littoralis showing the least frost resistance in summer and hence the greatest degree of hardening. Thermal analysis during freezing indicated that all three species became more tolerant of extracellular ice formation in winter. Measurements of chlorophyll a fluorescence correlated well with visible injury. The differing patterns of frost damage development in the three species were related to leaf anatomy: visible injury was localized within the small compartments formed by the highly septate leaves of the most resistant species, N. menziesii, and was somewhat localized in the partially septate leaves of P. eugenioides, whereas damage could be initiated anywhere in the aseptate leaves of G. littoralis,which was the least frost resistant species, particularly in summer.

Neuner G; Bannister P

1995-06-01

30

Frost resistance and susceptibility to ice formation during natural hardening in relation to leaf anatomy in three evergreen tree species from New Zealand.  

Science.gov (United States)

Foliar frost resistance of three endemic New Zealand land trees, Nothofagus menziesii (Hook. f.) Oerst. (Fagaceae), Pittosporum eugenioides A. Cunn. (Pittosporaceae) and Griselinia littoralis Forst. f. (Cornaceae), was examined as the trees hardened from late summer to midwinter in a lowland forest site. The lowest temperatures causing 50% damage (LT(50)) occurred in late winter and were similar to those recorded for other forest trees native to New Zealand (-11.7 degrees C in N. menziesii, -10.7 degrees C in P. eugenioides, and -10.6 degrees C in G. littoralis). All three species hardened by 4-7 degrees C, with G. littoralis showing the least frost resistance in summer and hence the greatest degree of hardening. Thermal analysis during freezing indicated that all three species became more tolerant of extracellular ice formation in winter. Measurements of chlorophyll a fluorescence correlated well with visible injury. The differing patterns of frost damage development in the three species were related to leaf anatomy: visible injury was localized within the small compartments formed by the highly septate leaves of the most resistant species, N. menziesii, and was somewhat localized in the partially septate leaves of P. eugenioides, whereas damage could be initiated anywhere in the aseptate leaves of G. littoralis,which was the least frost resistant species, particularly in summer. PMID:14965945

Neuner, G; Bannister, P

1995-06-01

31

Frost risks in the Mantaro river basin  

Directory of Open Access Journals (Sweden)

Full Text Available As part of the study on the Mantaro river basin's (central Andes of Perú) current vulnerability to climate change, the temporal and spatial characteristics of frosts were analysed. These characteristics included intensity, frequency, duration, frost-free periods, area distribution and historical trends. Maps of frost risk were determined for the entire river basin, by means of mathematical algorithms and GIS (Geographic Information Systems) tools, using minimum temperature – 1960 to 2002 period, geomorphology, slope, land-use, types of soils, vegetation and life zones, emphasizing the rainy season (September to April), when the impacts of frost on agriculture are most severe. We recognized four categories of frost risks: low, moderate, high and critical. The critical risks (with a very high probability of occurrence) were related to high altitudes on the basin (altitudes higher than 3800 m a.s.l.), while the low (or null) probability of occurring risks were found in the lower zones (less than 2500 m a.s.l.). Because of the very intense agricultural activity and the high sensitivity of the main crops (Maize, potato, artichoke) in the Mantaro valley (altitudes between 3100 and 3300 m a.s.l.), moderate to high frost risks can be expected, with a low to moderate probability of occurrence. Another significant result was a positive trend of 8 days per decade in the number of frost days during the rainy season.

G. Trasmonte; R. Chavez; B. Segura; J. L. Rosales

2008-01-01

32

Frost heave in He  

International Nuclear Information System (INIS)

Frost heave occurs in various phenomena in natural environment. It has been studied in helium on porous glasses under perfect ice-segregation condition. The maximum frost heave pressure was investigated for various conditions and was in good agreement with the thermodynamical prediction. The dynamical properties of frost heave are discussed and some of the preliminary results of the growth rate measurement are presented. (orig.)

1995-01-01

33

Martian wave of darkening: a frost phenomenon?  

UK PubMed Central (United Kingdom)

A new hypothesis attributes the Martian "wave of darkening" to soil frost phenomena. Diurnal thawing and freezing of the ground, which uses moisture transported by the atmosphere from the melting polar cap, can produce various minute, frost-heaved, soil surface features. These microrelief features result in a complex porous surface structure, which causes optical darkening. The boundary at which the wave of darkening terminates on the winter hemisphere correlates with the latitude at which the diurnal peak surface temperature drops below 0 degrees C. The hypothesis is examined in terms of known properties of the Martian atmosphere and surface and the availability of water.

Otterman J; Bronner FE

1966-07-01

34

Part 2. State of the art paper on frost heave : a review of frost heave theory and models  

Energy Technology Data Exchange (ETDEWEB)

This technical review for a proposed pipeline in the Mackenzie Valley in the Northwest Territories represents the first of 3 reports that document the current state of knowledge about frost heave theory, testing and predictive modelling. The review considers whether frost heave is sufficiently understood and can be controlled to allow for the safe construction and operation of a large diameter chilled gas pipeline. It provides a complete review of frost heavy theory, prediction models acquisition of input data for prediction models, validation of theory and models by laboratory experiments. Details on most of the significant models and experiments were presented on small scale frost heave experiments for northern pipeline design and operation, frost heave prediction models, and frost heave prediction models for buried chilled gas pipelines. The most recent developments applicable to chilled pipelines include the discrete ice lens model, the 2 dimensional rigid ice model, and the development of a 3 dimensional hydrodynamic model. The authors noted that a comprehensive analysis of the pipeline/frost heave problem should consider coupled heat flow and moisture transport in frozen and unfrozen soils; mechanical behaviour of unfrozen soil; moving boundary challenges associated with a moving freezing front and frost heave; growth of pore ice and ice lenses; mechanical behavior of the buried pipe; and pipeline-soil interface behaviour. The other 2 accompanying reports have also been catalogued separately for inclusion in this database. refs., tabs., figs.

NONE

2005-07-01

35

Frosted jones pyrex tubes.  

UK PubMed Central (United Kingdom)

PURPOSE: To describe the use of a new, frosted Jones Pyrex tube in the treatment of obstructed canaliculi of the upper lacrimal system. The frosted Jones tube retains the advantages of the traditional smooth Pyrex tube yet appears to improve the positional stability in the surgically created fistula. METHODS: Ten patients of a single surgeon who had previously undergone external conjunctivodacryocystorhinostomy and placement of a Jones Pyrex tube, with subsequent Pyrex tube extrusion, were included in the study. All had previous success with Pyrex tubes, with follow-up ranging from 1 month to 14 years. In each case, when the patient presented with an extruded tube, it was replaced with a frosted Jones tube (Weiss Scientific Glass Blowing Company, Portland, OR, U.S.A.). RESULTS: In this preliminary study, none of the 10 patients fitted with a frosted Jones Pyrex tube had a recurrence of extrusion. All patients reported proper functioning of the tubes, with no complaints of epiphora or discomfort. CONCLUSIONS: Compared with a standard Jones Pyrex tube, a frosted tube functions equally well and reduces the possibility of extrusion, which is the main complication of traditional conjunctivodacryocystorhinostomy. We have exchanged smooth tubes for frosted tubes in patients who have had extrusion of the original tube, and we are currently investigating primary placement of the frosted Jones Pyrex tube.

Dailey RA; Tower RN

2005-05-01

36

Soil magnetic susceptibility reflects soil moisture regimes and the adaptability of tree species to these regimes  

Science.gov (United States)

Flooded, saturated or poorly drained soils are frequently anaerobic, leading to dissolution of the strongly magnetic minerals, magnetite and maghemite, and a corresponding decrease in soil magnetic susceptibility (MS). In this study of five temperate deciduous forests in east-central Illinois, USA, mean surface soil MS was significantly higher adjacent to upland tree species (31 ?? 10-5 SI) than adjacent to floodplain or lowland tree species (17 ?? 10-5 SI), when comparing regional soils with similar parent material of loessal silt. Although the sites differ in average soil MS for each tree species, the relative order of soil MS means for associated tree species at different locations is similar. Lowland tree species, Celtis occidentalis L., Ulmus americana L., Acer saccharinum L., Carya laciniosa (Michx. f.) Loud., and Fraxinus pennsylvanica Marsh. were associated with the lowest measured soil MS mean values overall and at each site. Tree species' flood tolerance rankings increased significantly, as soil MS values declined, the published rankings having significant correlations with soil MS values for the same species groups. The three published classifications of tree species' flood tolerance were significantly correlated with associated soil MS values at all sites, but most strongly at Allerton Park, the site with the widest range of soil drainage classes and MS values. Using soil MS measurements in forests with soil parent material containing similar initial levels of strongly magnetic minerals can provide a simple, rapid and quantitative method to classify soils according to hydric regimes, including dry conditions, and associated plant composition. Soil MS values thus have the capacity to quantify the continuum of hydric tolerances of tree species and guide tree species selection for reforestation. ?? 2007 Elsevier B.V. All rights reserved.

Wang, J. -S.; Grimley, D. A.; Xu, C.; Dawson, J. O.

2008-01-01

37

Soil Liquefaction Susceptibility and Site Class Maps of Washington State  

Science.gov (United States)

In response to the Nisqually earthquake of 2001, the Washington State Division of Geology and Earth Resources (DGER) developed two types of earthquake hazard maps for every county in the state: liquefaction susceptibility maps, which outline areas where water-saturated sandy soil loses strength during earthquake shaking, and National Earthquake Hazards Reduction Program (NEHRP) site class maps, which outline areas where soils amplify ground shaking. The maps will be used by state and local governments in Washington to update existing hazard mitigation plans and to delineate geologically hazardous areas for emergency planning and response, planning of local zoning ordinances, and building code enforcement. A link is provided to an ftp site where the maps are stored in folders.

38

Machine learning modelling for predicting soil liquefaction susceptibility  

Directory of Open Access Journals (Sweden)

Full Text Available This study describes two machine learning techniques applied to predict liquefaction susceptibility of soil based on the standard penetration test (SPT) data from the 1999 Chi-Chi, Taiwan earthquake. The first machine learning technique which uses Artificial Neural Network (ANN) based on multi-layer perceptions (MLP) that are trained with Levenberg-Marquardt backpropagation algorithm. The second machine learning technique uses the Support Vector machine (SVM) that is firmly based on the theory of statistical learning theory, uses classification technique. ANN and SVM have been developed to predict liquefaction susceptibility using corrected SPT [(N1)60] and cyclic stress ratio (CSR). Further, an attempt has been made to simplify the models, requiring only the two parameters [(N1)60 and peck ground acceleration (amax/g)], for the prediction of liquefaction susceptibility. The developed ANN and SVM models have also been applied to different case histories available globally. The paper also highlights the capability of the SVM over the ANN models.

P. Samui; T. G. Sitharam

2011-01-01

39

Genetically engineered microorganisms to rescue plants from frost injury.  

UK PubMed Central (United Kingdom)

Ice nucleation active bacteria belonging to genera Pseudomonas, Xanthomonas and Erwinia contribute to frost damage to plants by initiating the formation of ice in plants that would otherwise supercool and avoid the damaging ice formation. The biological control of frost injury can be achieved by the application of non-ice nucleation active bacteria to the plant surfaces before they become colonized by Ice+ species. ice genes have been cloned from Pseudomonas and isogenic Ice- derivatives constructed via genetic manipulations. These genetically engineered microorganisms (GEMs) have been released into the environment to control the frost damage. The incidence of frost injury to the plants has, thereby, been reduced by 50-85% during natural frosts. These GEMs do not survive in soil and show no aerial dispersal in the environment.

Dar GH; Anand RC; Sharma PK

1993-01-01

40

Genetically engineered microorganisms to rescue plants from frost injury.  

Science.gov (United States)

Ice nucleation active bacteria belonging to genera Pseudomonas, Xanthomonas and Erwinia contribute to frost damage to plants by initiating the formation of ice in plants that would otherwise supercool and avoid the damaging ice formation. The biological control of frost injury can be achieved by the application of non-ice nucleation active bacteria to the plant surfaces before they become colonized by Ice+ species. ice genes have been cloned from Pseudomonas and isogenic Ice- derivatives constructed via genetic manipulations. These genetically engineered microorganisms (GEMs) have been released into the environment to control the frost damage. The incidence of frost injury to the plants has, thereby, been reduced by 50-85% during natural frosts. These GEMs do not survive in soil and show no aerial dispersal in the environment. PMID:8213308

Dar, G H; Anand, R C; Sharma, P K

1993-01-01

 
 
 
 
41

Changes in frost days in simulations of twentyfirst century climate  

Energy Technology Data Exchange (ETDEWEB)

Global coupled climate model simulations of twentieth and twentyfirst century climate are analyzed for changes in frost days (defined as nighttime minima less than freezing). The model simulations agree with the observed pattern for late twentieth century of a greater decrease of frost days in the west and southwest USA compared to the rest of the country, and almost no change in frost days in fall compared to relatively larger decreases in spring. Associated with general increases of nighttime minimum temperatures, in the future climate with increased greenhouse gases (GHGs) the number of frost days is fewer almost everywhere, but there are greatest decreases over the western parts of the continents. The numbers of frost days are most consistently related to sea level pressure, with more frost days occurring when high pressure dominates on the monthly time scale in association with clearer skies and lower nighttime minimum temperatures. Spatial patterns of relative changes of frost days are indicative of regional scale atmospheric circulation changes that affect nighttime minimum temperatures. Increases of soil moisture and clouds also contribute, but play secondary roles. The linkages among soil moisture, clouds, sea level pressure, and diurnal temperature range are quantified by a statistical multiple regression model. Coefficients for present and future climate are similar among the predictors, indicating physical processes that affect frost days in present and future climates do not appreciably change. Only the intercept changes in association with the significant warming of the mean climate state. This study highlights the fact that, though there is a general decrease in the number of frost days with global warming, the processes that affect the pattern of those changes, and thus the regional changes of frost days, are influenced by several interrelated physical processes, with changes in regional atmospheric circulation generally being most important. (orig.)

Meehl, G.A.; Tebaldi, C.; Nychka, D. [National Center for Atmospheric Research, PO Box 3000, Boulder, CO 80307 (United States)

2004-10-01

42

The regional and temporal variation of frost in natural conditions in Finland. Luonnontilaisen roudan alueellinen ja ajallinen vaihtelu Suomessa  

Energy Technology Data Exchange (ETDEWEB)

The frost sum and the snow depth are the major factors effecting frost depth. In addition, the type of terrain and soil. as well as the ground water level and soil moisture have an effect on the soil freezing and thawing. The regional variations in soil freezing and thawing are explained by the timing of snowfall versus the starting time of frost weather. For example, there is often more soil frost in southwestern Finland than in the Kuusamo area, in the north. Soil freezing and thawing occur more rapidly in coarse or moist soils than in fine or dry soils. Frost penetrates deeper under a spruce forest than it does in open land, because snowfall is detained by the canopy and is not able to form an isolating layer on the ground. Conversely, soil frost is not as deep in deciduous and tall pine forests as it is in open land, because the snow accumulates below the tree stand and shelters the ground. The Hydrological Office has been regularly measuring frost depth since the early 1950's. This study deals mainly with frost depths dating from the late 1960's to as recent as the winter of 1989/90. Some series from the 1950's were primarily analyzed to perform some calculations on recurrence. Frost penetration and thawing, the length of freezing period, as well as the frost maximum and its recurrence are shown in state wide maps, statistic figures and tables

Huttunen, L.; Soveri, J.

1993-01-01

43

Subsoil investigation of ice lensing at the Calgary, Canada, frost heave test facility  

Energy Technology Data Exchange (ETDEWEB)

Several frost heave mitigation modes were studied at the Calgary, Canada, chilled pipeline frost heave test facility. These included deeper burial (to increase the pressure on the frost front below the pipe) and replacement of the silty soil around the pipe with gravel for a noninsulated pipe. Frost heave at the deep-burial section and at the gravel section was less than the heave at a control section. Other pipe sections tested the effects of insulation of the pipe on the long-term frost heave, as well as the results in seasonal thaw settlement of the pipe, thus reducing the long-term pipe heave, at least for the warmer ground temperature environment at the Calgary facility. Thermal simlations of the frost bulb growth and predictions of frost heave using the segregation potential model agree well with the observations. Recent excavation of two frost bulbs in silty soil led to field observations of the interior of the frost bulbs, and subsequent laboratory analysis of frost bulb samples. Ice distribution was logged and photographed following excavation of each frost bulb. 8 refs., 15 figs.

Carlson, L.E.; Nixon, J.F.D.

1988-05-01

44

Discrete ice lens theory for frost heave beneath pipelines  

Energy Technology Data Exchange (ETDEWEB)

The discrete ice lens theory of frost heave in 1-dimensional soil columns has been extended to the 2-dimensional heat- and mass-flow situation beneath a buried chilled pipeline. Although the soil regions beneath such a pipeline are 2-dimensional, and the temperature and water-flow fields are potentially complex, considerable simplifications can be made by invoking a quasi-static approach for estimating temperature fields around the buried pipeline. It is proposed that the curved, quasi-static temperature profiles available from published relationships are appropriate for frost heave predictions in the 2-dimensional region beneath a pipeline. Using these curved temperature profiles in the same program and solution procedure previously developed for 1-dimensional soil columns allows frost heave predictions for a buried pipeline to be carried out with a minimum of computational effort. The procedure was used to predict the frost depth and heave beneath two well-documented pipeline test sections in Calgary, Alberta and Caen, France. Very good agreement between prediction and observation was obtained. Some predictions for a practical field situation indicate the initial ground temperature plays an important role in frost heave, frost penetration, and the time at which the final ice lens forms in the freezing soil. 15 refs., 13 figs.

Nixon, J.F. (Nixon Geotech Ltd., Calgary, AB (Canada))

1992-01-01

45

Effects of Parent Materials, Gypsum and Carbonates on the Magnetic Susceptibility of Soils in Southern Mashhad  

Directory of Open Access Journals (Sweden)

Full Text Available Magnetic susceptibility measurement is a simple and quick technique for characterizing soils and sediments and describing soil-forming processes. The interpretation of soil magnetic susceptibility data needs sufficient knowledge about the factors affecting this parameter. To identify the effects of parent material, gypsum and calcium carbonate equivalent, 42 samples were taken from horizons of soils developed on loessial, alluvial, granitic and marly materials in southern Mashhad. Gypsum and carbonates of soil samples were removed by successive washing with distilled water and diluted HCl, respectively. Magnetic susceptibility of bulk samples (?lfbulk), gypsum free samples (?lfGf), gypsum and carbonates free samples (?lfGCf) and gypsum, carbonates and sand free samples (?lfGCSf) was measured. The results revealed a strong 1:1 correlation between the measured and calculated ?lfGf and ?lfGCf. Despite the high amounts of gypsum and carbonates in soils developed on marls, their ?lfbulk was much more than that of the other soils and reached up to 121.8×10-8m3 kg-1. In contrast, the ?lfbulk values of saprolitic granite were less than 10.4×10-8m3 kg-1. The ?lfbulk values of loessial and alluvial soils were less than those of marly soils but higher than those of soils developed on saprolitic granite. ?lfbulk values were negatively correlated with the amount of sand. However, reduction in magnetic susceptibility values of marly soils after removing sand reflects the different nature of this soil. The correlation between ?lfbulk and amount of silt and clay is positive, but the magnetic susceptibility values are more sensitive to clay percentage, indicating the more important contribution of clay to magnetic susceptibility values. The results of this study highlight the role of parent materials, gypsum and carbonates in the soil magnetic susceptibility values that should be considered.

A. Karimi; H. Khademi

2012-01-01

46

Frost resistance of reproductive tissues during various stages of development in high mountain plants.  

UK PubMed Central (United Kingdom)

Frost resistance of reproductive vs aboveground vegetative structures was determined for six common European high alpine plant species that can be exposed to frosts throughout their whole reproductive cycle. Freezing tests were carried out in the bud, anthesis and fruit stage. Stigma and style, ovary, placenta, ovule, flower stalk/peduncle and, in Ranunculus glacialis, the receptacle were separately investigated. In all species, the vegetative organs tolerated on an average 2-5 K lower freezing temperatures than the most frost-susceptible reproductive structures that differed in their frost resistance. In almost all species, stigma, style and the flower stalk/peduncle were the most frost-susceptible reproductive structures. Initial frost damage (LT??) to the most susceptible reproductive structure usually occurred between -2 and -4°C independent of the reproductive stage. The median LT?? across species for stigma and style ranged between -3.4 and -3.7°C and matched the mean ice nucleation temperature (-3.7 ± 1.4°C). In R. glacialis, the flower stalk was the most frost-susceptible structure (-5.4°C), and was in contrast to the other species ice-tolerant. The ovule and the placenta were usually the most frost-resistant structures. During reproductive development, frost resistance (LT??) of single reproductive structures mostly showed no significant change. However, significant increases or decreases were also observed (2.1 ± 1.2 K). Reproductive tissues of nival species generally tolerated lower temperatures than species occurring in the alpine zone. The low frost resistance of reproductive structures before, during and shortly after anthesis increases the probability of frost damage and thus, may restrict successful sexual plant reproduction with increasing altitude.

Neuner G; Erler A; Ladinig U; Hacker J; Wagner J

2013-01-01

47

Frost resistance of reproductive tissues during various stages of development in high mountain plants  

UK PubMed Central (United Kingdom)

Frost resistance of reproductive vs aboveground vegetative structures was determined for six common European high alpine plant species that can be exposed to frosts throughout their whole reproductive cycle. Freezing tests were carried out in the bud, anthesis and fruit stage. Stigma and style, ovary, placenta, ovule, flower stalk/peduncle and, in Ranunculus glacialis, the receptacle were separately investigated. In all species, the vegetative organs tolerated on an average 2–5 K lower freezing temperatures than the most frost?susceptible reproductive structures that differed in their frost resistance. In almost all species, stigma, style and the flower stalk/peduncle were the most frost?susceptible reproductive structures. Initial frost damage (LT??) to the most susceptible reproductive structure usually occurred between ?2 and ?4°C independent of the reproductive stage. The median LT?? across species for stigma and style ranged between ?3.4 and ?3.7°C and matched the mean ice nucleation temperature (?3.7 ± 1.4°C). In R. glacialis, the flower stalk was the most frost?susceptible structure (?5.4°C), and was in contrast to the other species ice?tolerant. The ovule and the placenta were usually the most frost?resistant structures. During reproductive development, frost resistance (LT??) of single reproductive structures mostly showed no significant change. However, significant increases or decreases were also observed (2.1 ± 1.2 K). Reproductive tissues of nival species generally tolerated lower temperatures than species occurring in the alpine zone. The low frost resistance of reproductive structures before, during and shortly after anthesis increases the probability of frost damage and thus, may restrict successful sexual plant reproduction with increasing altitude.

Neuner G; Erler A; Ladinig U; Hacker J; Wagner J

2013-01-01

48

Frost heave-pipeline interaction using continuum mechanics  

Energy Technology Data Exchange (ETDEWEB)

As a chilled pipeline crosses a transition from frozen to unfrozen ground or shallow permafrost, a differential frost heave problem may develop causing strains in the pipe. Soil-structure interaction models that are currently available to handle this problem concentrate on the pipe as the dominant structural member and represent the soil mass as a series of unconnected springs. This paper considers the soil to be an elastic or nonlinear viscous continuum and imposes a nonlinear boundary condition to represent the frost heaving soil and the dependence of frost heave on applied pressure. The pipe is assumed to be a completely passive structural member and the soil strains at the pipe elevations are studied. The dependence of the maximum pipe strains on the length of the heaving section and on the thickness of frozen ground beneath the pipe have been established for a typical set of soil and frost heaving conditions. It is found that, for the conditions studied, when the thicknes of shallow permafrost or frozen soil is greater than about 7-8 m, the strains that a flexible pipe experiences are less than the strain criteria currently in use on many pipeline projects.

Nixon, J.F.; Morgenstern, N.R.; Reesor, S.N.

1983-05-01

49

Relationship between Magnetic Susceptibility and Heavy Metals Concentration in Polluted Soils of Lenjanat Region, Isfahan  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This study analyzed the relationship between soil magnetic susceptibility and the content of Cd, Cu, Ni, and Fe on 233 samples from polluted soils of Lenjanat Region in the Isfahan. The aim was to investigate the suitability of such measurements for indicating heavy metal pollution. Heavy metal con...

Salehi M. H.; Jorkesh SH.; Mohajer R.

50

Percolation-induced frost formation  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We report the observation of an unconventional mechanism for frost formation. On a smooth hydrophobic surface cooled much below the water freezing temperature (?9 °C), we find that, instead of the classical freezing of individual supercooled condensed droplets, frost can occur through a multi-step 2...

51

Relationship between Magnetic Susceptibility and Heavy Metals Concentration in Polluted Soils of Lenjanat Region, Isfahan  

Directory of Open Access Journals (Sweden)

Full Text Available This study analyzed the relationship between soil magnetic susceptibility and the content of Cd, Cu, Ni, and Fe on 233 samples from polluted soils of Lenjanat Region in the Isfahan. The aim was to investigate the suitability of such measurements for indicating heavy metal pollution. Heavy metal contents were determined after extraction with nitric acid. Basic soil characteristics were determined using common methods. Geochemical analysis of soil samples showed close correlation between Cd, Ni and Fe. Cd concentration was the highest of all the elements studied. The correlation between the analyzed metals and magnetic susceptibility are positive and significant for Fe and Cu. Results suggests that magnetic susceptibility can be used as a guideline to find contaminated urban areas with Fe and Cu in this region.

Salehi M. H.; Jorkesh SH.; Mohajer R.

2013-01-01

52

Pinhole test for identifying susceptibility of soils to piping erosion: effect water quality and hydraulic head  

International Nuclear Information System (INIS)

[en] Piping has been observed in both natural and soils, as well as under different types of land uses and vegetation covers. Despite its importance, no standard widely-applied methodology exists to assess susceptibility of soils to piping. This study aims at evaluating the pinhole test for assessing the susceptibility of soils to piping under different conditions. More precisely, the effects of hydraulic head and water quality are being assessed. Topsoil samples (remoulded specimens) with a small range of water contents were taken in Central Belgium (Heverlee) and the susceptibility of these soil samples are investigated under standardized laboratory conditions with a pinhole test device. Three hydraulic heads (50,180 and 380 mm) and two water qualities (tap and distilled water) were used, reflecting dominant field conditions. (Author) 6 refs.

2009-01-01

53

Large scale magnetic susceptibility soil mapping: a proxy for geological mapping and exploration from Bogoso (Ghana)  

Science.gov (United States)

This paper describes the use of magnetic susceptibility measurements on a set of nearly 3000 soil samples (one sample per km2) collected for geochemical analyses within the framework of a geological mapping program in Ghana. The result is a map of soil magnetic susceptibility which has been compared with other maps. There is a good consistency with geological domains and lithologies, as well as with some of the geochemical soil analyses and also partly with the aeromagnetic data. In the tropical, deeply weathered lateritic context of the study area, soil magnetic susceptibility reveals similarities with magnetic and/or geochemical survey results, suggesting this rapid and easy to use technique can be an effective tool for exploration and geological mapping programs.

Théveniaut, Hervé; Clarke, Brendan

2013-01-01

54

Pinhole test for identifying susceptibility of soils to piping erosion: effect water quality and hydraulic head  

Energy Technology Data Exchange (ETDEWEB)

Piping has been observed in both natural and soils, as well as under different types of land uses and vegetation covers. Despite its importance, no standard widely-applied methodology exists to assess susceptibility of soils to piping. This study aims at evaluating the pinhole test for assessing the susceptibility of soils to piping under different conditions. More precisely, the effects of hydraulic head and water quality are being assessed. Topsoil samples (remoulded specimens) with a small range of water contents were taken in Central Belgium (Heverlee) and the susceptibility of these soil samples are investigated under standardized laboratory conditions with a pinhole test device. Three hydraulic heads (50,180 and 380 mm) and two water qualities (tap and distilled water) were used, reflecting dominant field conditions. (Author) 6 refs.

Nadal Romero, E.; Verachtert, E.; Poesen, J.

2009-07-01

55

Field measurements of frost penetration into a landfill cover that uses a paper sludge barrier  

Energy Technology Data Exchange (ETDEWEB)

Frost penetration is a major environmental concern in landfill design. Freezing and thawing cycles may deteriorate the permeability of the liner or cap. In this study, the depth of frost penetration into a landfill cover that uses paper sludge as the impermeable barrier (the Hubbardston landfill in Massachusetts) was measured using a frost measurement system. A thermistor probe measured the temperature at various depths. Although temperature measurements are important, soil resistivity measurements are required to accurately predict the freezing level, since soil resistivity increases greatly upon freezing. A conductivity probe measured the half-bridge voltage between conductivity rings and a ground rod. Data were collected in data loggers. The data collected from 1992--1996 showed that the frost level did not penetrate the paper sludge capping layer. Heavy snow cover throughout the winters decreased the depth of frost penetration by insulating the landfill. The high water content in the sludge also contributed to the lack of freezing.

Moo-Young, H.K.; LaPlante, C.; Zimmie, T.F.; Quiroz, J.

1999-07-01

56

Restraint of frost heave in a test filling using lime stabilization; Shiken moritsuchi ni okeru sekkai antei shori no tojo yokusei koka  

Energy Technology Data Exchange (ETDEWEB)

This paper describes restraint of frost heave in a test filling frost waste soil from construction using lime stabilization. The restraint of frost heave is significant for the road design in cold districts, and replacement has been conventionally adopted. However, due to the exhaustion of replacement materials which are a great amount of coarse grain materials and the treatment of waste soil, construction method using soil generated at original site has been required. The frost depth of stabilized soil using untreated soil and site soil is constant between 68 and 70 cm. The restraint effect of frost heave was enhanced with increasing the lime addition. The addition of 10% lime decreased the frost heave to 4 mm which was of the same order experienced in the sand replacement method. Through the lime stabilization, the frost heave can be suppressed by the reduction of permeability and by the increase in intergranular force due to pozzolanic reaction. Based on the relationship between the frost depth and frost heave, it was found that the frost heave of soil stabilized by lime concentrates on the surface part of improved layer. This was considered to be caused by the increase in the water content of upper layer with rain water and snowmelt water due to the uneven mixing of improving agent and the reduction of permeability of treated layer. 9 refs., 8 figs.

Kawabata, S.; Kamiya, M. [Hokkaido Institute of Technology, Sapporo (Japan); Osawa, M.

1998-04-01

57

Practical prediction method for frost heave taking ground water table into consideration; Chika suii wo koryoshita jitsuyotekina tojoryo no setteiho  

Energy Technology Data Exchange (ETDEWEB)

Traffics are obstructed by the frost heave by which pavement is partially risen. Frost heave occurs frequently at cut-off slopes and low embankments, and does not occur at normal embankments. This paper describes effects of ground water table on the frost heaving. A series of full-scale and in-situ freezing tests were performed in the laboratory and at the embankment in the field. For the embankments using mixed soil, Tomakomai soil and Asahikawa soil, the frost heaving decreased rapidly when depth of the ground water table was more than 2 m. The frost heaving depended greatly on the initial water content of freezing soils. For the Towada soil with high initial water content, strong frost heave occurred due to water contained in itself. The frost heaving did not decrease even when depth of the ground water table increased. When arranging the results of full-scale freezing tests for five kinds of soils based on the water content, close relationships were found among the ground water table, initial water content and freezing rate. As a result of the in-situ tests, the frost heaving decreased with increasing the depth of ground water table. In-situ observation results could be explained in a certain degree by the freezing rate prediction equation. 15 refs., 23 figs., 5 tabs.

Yokota, S.; Mishima, N. [Japan Highway Public Corporation, Tokyo (Japan); Miura, S. [Muroran Institute of Technology, Hokkaido (Japan)

1997-09-20

58

Modeling of frost growth and frost properties with airflow over a flat plate  

Energy Technology Data Exchange (ETDEWEB)

A physical model of frost layer growth and frost properties with airflow over a flat plate at subfreezing temperature was developed. Frost roughness was measured, and a empirical correlation for the average frost roughness was suggested. Heat and mass transfer coefficients were calculated using the modified Prandtl mixing-length scheme containing the effects of both frost roughness and turbulent boundary layer thickness. Frost thermal conductivity was theoretically analysed by solving the combined equations of air equivalent conductivity and thermal conductivity of the frost inner layer. Based on the present model, heat and mass transfer coefficient, frost thermal conductivity, frost thickness, frost mass concentration and frost density with time and space were estimated. The model showed good agreement with the basic trends of the test data taken from other literature. Spatial and temporal changes of heat flux and frost surface temperature were also investigated. (Author)

Rin Yun; Yongchan Kim; Manki Min [Korea Univ., Dept. of Mechanical Engineering, Seoul (Korea)

2002-05-01

59

Dynamics of frost resistance in various provenances of Abies grandis Lindl.  

Directory of Open Access Journals (Sweden)

Full Text Available The frost resistance of one year old needles and shoots of Abies grandis (seven provenances) and Abies alba (one provenance) was determined using Dexter's method since early autumn till late spring (September-May). Material was collected from trees over ten year old, planted in Beskid S?decki Range near Krynica, 800 m above sea level. In this study it was found, that in early autumn (September) A. grandis develops weaker frost hardiness than Abies alba. In the late autumn and in winter, provenances coming from region II (according to Müller), and especially provenance 12016, are equal in respect to frost hardiness of shoots and needles to Abies alba. Among the provenances from Müller's region I exceptional frost hardiness is displayed by provenance 12005, which is also characterized by fast growth. In spring, Abies alba flushes earlier than A. grandis, which makes it more susceptible to late frosts.

Adam Dolnicki; Wojciech Kraj

1998-01-01

60

Frost formation mechanism analysis and frost growth prediction on ground aircraft  

Science.gov (United States)

Frost predictions are needed to help the deicing operation decide. The mechanism of frost formation on aircraft surface under icing conditions has been analyzed. A simple theoretical frost growth prediction model by heat and mass transfer analysis has been presented. It produces a method to forecast the frost growth tendency. An experimental system for atmospheric frost reproduction is also presented. Effects of aircraft surface temperatures, air temperature on the frost growth is evaluated by this model.

Xu, Dandan; Wang, Liwen

2013-10-01

 
 
 
 
61

A study of the utilization of coal ash as a civil engineering material (III): a material for preventing frost heave displacement in ground around underground storage tanks for low-temperature liquids  

Energy Technology Data Exchange (ETDEWEB)

Coal ash generally has a small specific surface area and therefore shows little frost heave. Its applicability as the type of suppressant referred to in the title was accordingly investigated. It was concluded that it shows less frost heave than sandy soil and that it gives greater frost swelling protection. Frost heave tests were carried out under fixed freezing rates and upper loading pressures, and the effects of specific surface area and particle size on amount of frost heave were studied. Changes with time in the amount of frost heave were also investigated. The test results substantiated an analysis in terms of thermal conduction in a spherical model. (5 refs.) (In Japanese)

Ryokai, K.

1982-01-01

62

Frost. Vol. 6. Gel. Vol. 6  

Energy Technology Data Exchange (ETDEWEB)

This publication presents in a concise form the means, extremes and probabilities of frost occurrence recorded at 2,250 stations in Canada. Normals are from the 30-year period 1951-1980. Extremes are for the full period of station record with this period in years indicated in the tables. Probability values are based on a minimum 10 years and a maximum 50 years of data from 1931 to 1980. Three significant frost events are listed: the last occurrence of frost in spring, the first occurrence of frost in fall and the mean number of days between these occurrences or the frost-free period. Mean frost-free periods and average dates of last frost in spring and first frost in fall were obtained from daily temperature records over the period from 1951-1980 or from whatever portion of that period that data were available, providing the period exceeded five years. Extremes of these frost data are based on the entire period of record at each station up to and including 1980. Probability tables are included for seven percentages (10, 25, 33, 50, 66, 75, 90) for last spring frost and first fall frost and for the frost-free period. In all tables, stations are arranged alphabetically within province and territory. 2 refs., 4 tabs.

1982-01-01

63

Tolerância de frutos de pessegueiro a geadas Fruit frost tolerance in peach  

Directory of Open Access Journals (Sweden)

Full Text Available Este trabalho teve como objetivo avaliar a tolerância de frutos de pessegueiro aos danos ocasionados pela geada. A geada ocorreu no dia 5 de setembro de 2006, sendo que a temperatura mínima, a 1,5 m do solo, foi de - 1,06ºC. Foram avaliados 28 genótipos de pessegueiro em diferentes estádios fenológicos. O delineamento experimental foi o inteiramente casualizado, com três repetições (plantas de pessegueiro), procedendo-se à avaliação em seis ramos por planta. No dia em que ocorreu a geada, foram mensurados o número de frutos por ramo, diâmetro sutural médio dos frutos, número total de gemas vegetativas, percentual de brotação e percentual de brindilas formadas a partir das gemas brotadas. Uma segunda avaliação foi realizada 15 dias após a primeira, para avaliar o percentual de queda de frutos e o diâmetro sutural médio dos frutos remanescentes. Genótipos bem enfolhados e cujos frutos apresentavam endocarpo endurecido, no momento da ocorrência da geada, foram tolerantes ao dano ocasionado pelo frio; frutos com diâmetro sutural inferior a 20 mm foram suscetíveis à geada, enquanto frutos com diâmetro sutural superior a 30 mm apresentaram boa tolerância, independentemente do genótipo avaliado.The aim of this work was to evaluate the fruit damage tolerance in different peach tree genotypes after natural freeze. The frost happened on September 5, 2006, and the minimum temperature, 1.5 meters over soil, was -1.06ºC. Twenty- eight peach tree genotypes, in different stages of development, were evaluated, in a completely random design, in three replication (plants) and six branches by plants. Immediately after frost, we measured the number of fruits per branches, average fruit suture diameter, percentage of sprouts and percentage of twigs in formation. A second evaluation was accomplished fifteen days after the first one in order to assess the percentage of fruit drop and the average remaining fruit suture diameter. Genotypes with good leafing and hard pit (endocarp) during frost have freeze tolerance; fruits with suture diameter lass than 20 mm are susceptible to frost damage, while fruits with suture diameter superior to 30 mm are tolerant.

André Paulo Assmann; Idemir Citadin; Mauro Cristovão Locatelli; Silvia Scariot; Moeses Andrigo Danner; Maria do Carmo Bassols Raseira

2008-01-01

64

Subsoil compaction in Flanders: from soil map to susceptibility map and risk map for subsoil compaction  

Science.gov (United States)

In contrast to topsoil compaction, which can be remediated by normal soil tillage and natural loosening processes, subsoil compaction must be considered as a long term threat to soil productivity as this form of compaction is much more persistent and not easy to alleviate. Therefore we focused on subsoil compaction with a view to demarcate areas prone to soil compaction in Flanders, Belgium. The susceptibility of soil material to compaction is inversely related to its structural strength which can be expressed in terms of precompression stress (PCS). In order to construct maps of subsoil susceptibility we upgraded the soil map of Flanders, originally printed at a scale of 1:20.000, by attributing a ‘typical' PCS-value to the legend units. These PCS-values were estimated by means of pedotransfer functions (PTFs), valid either at pF 1.8 or pF 2.5, elaborated from PCS-measurements on soils in Germany by Lebert and Horn (1991). Predictor values for the PTFs were supplied by or derived by means of other PTFs from a historical database of georeferenced soil profiles, which were analysed between 1947 and 1971. After regional stratification, soil profiles with associated horizons were linked to soil map units based on corresponding classification units. Next, for each map unit the horizon at 40 cm of depth was selected and its characteristics retrieved for use in the PTFs. The two resulting PCS-maps (pF 1.8 or 2.5) show the susceptibility to compaction of almost uncompacted or little compacted arable soils as they were present in the period 1950-1970, when the wheel loads of the agricultural equipment of that time were much lower compared to the wheel loads that are common today. Both maps of inherent susceptibility at fixed pF were combined into a ‘hybrid map' of the inherent susceptibility to subsoil compaction in spring, when the groundwater table is at its highest level and correspondingly also the susceptibility to compaction is highest. Each soil map unit was assigned the PCS-value calculated for pF 2.5 or the PCS-value calculated for pF 1.8, based on a decision rule. This rule was based on the expected depth of the groundwater table in spring, from which we calculated the expected pF-value at 40 cm of depth. Then, for each soil map unit this calculated pF was compared to pF 2.5, respectively pF 1.8 in order to determine the closest of the two pF-values and the corresponding PCS-value. Based on the developed susceptibility maps so called ‘risk maps' were constructed which show the modeled maximum allowable wheel load that may be exerted on the surface of each soil map unit by either (i) a 480/80R42 tractor tyre or (ii) a 800/65R32 tyre of a sugarbeet harvester in order not to exceed the estimated ‘pre-compaction PCS' at 40 cm of depth. Therefore we calculated the normal stresses generated by those tyres on the 40 cm reference depth, by making use of the analytical soil compaction model SoilFlex (Keller et al., 2007). Based on the results of a parallel study (Van Holm et al., 2010) in which different soil compaction related parameters were measured on subsoil samples (40 cm) of 17 arable fields, belonging to different soil textural classes and distributed all over Flanders, we could conclude that a severe compaction of subsoil material has taken place since the period 1950-1970 as the PCS-values determined in 2009 for those fields (by uniaxial compaction tests and the Casagrande method; Casagrande, 1936) were always (much) higher then the PCS-values retrieved for the same soil map units from the inherent susceptibility map (= historical map) for the same depth. Knowledge about actual soil bulk density is an important key to actualise the developed maps.

van de Vreken, Philippe; van Holm, Lieven; Diels, Jan; van Orshoven, Jos

2010-05-01

65

Determination of anthropogenic boundary depth in industrially polluted soil and semi-quantification of heavy metal loads using magnetic susceptibility  

International Nuclear Information System (INIS)

This study focuses on magnetic susceptibility processing and analysis towards fast and cost-efficient discrimination and semi-quantification of anthropogenic heavy metal loads in soil. Spatial variability of magnetic susceptibility was investigated on sets of soil cores from both 'polluted' and 'less polluted' forest soil close to a steel mill near Leoben, Austria. Test sites of ?10 m2 represent 'site scale' dimensions. Statistical analysis of magnetic data provides a boundary depth indicating the transition from the 'polluted' to the deeper, 'unpolluted' zone in contaminated natural soil. Introduction of a block master curve simplifies the complex variations of individual curves, and represents magnetic susceptibility at 'site scale'. For linking the block master curve to heavy metals we only require magnetic susceptibility data from one soil core and heavy metal data from two sub-samples from the same core. Our optimized magnetic susceptibility data processing scheme provides an applicable tool to semi-quantify anthropogenic heavy metal loads in soil. - Our method allows standardized semi-quantification of anthropogenic heavy metal loads in soils by magnetic susceptibility processing plus only two heavy metal analyses

2008-01-01

66

Coreopsis plant named 'Ruby Frost'  

UK PubMed Central (United Kingdom)

A new and distinct Coreopsis plant named 'Ruby Frost' characterized by large, daisy-type flowers that grow to 5.5 cm in diameter, white-edged red purple flowers, grass green foliage on short stems, flowering for the whole summer, and a dense, mounding habit.

KORLIPARA HARINI

67

Changes in cerrado vegetation after disturbance by frost (Sao Paulo State, Brazil).  

UK PubMed Central (United Kingdom)

We report changes after frost in cerrado species populations and community structure in Assis, Sao Paulo State, Brazil and consider the possible impacts of frost on cerrado types and their distribution. Four permanent plots (10 m x 10 m) were established and 736 individuals were marked with enumerated plastic labels and measured one week after the frost. Frost damage for each individual was assessed: 0 - not affected; 1 - slightly affected; 2 - substantially affected; and 3 - strongly affected. The frost impact on vegetation structure was high, reducing tree canopy cover from 88% to 19% in the upper stratum and that of the lower stratum from 48% to 8.5%. Floristic richness did not change, even though a small number (3%) of individuals of some species died. Conversely, the relative dominance of species changed dramatically in the short-term because of varying susceptibility to frost of different species. The largest reductions in crown cover were observed in Xylopia aromatica and Vochysia tucanorum. Of the 57 species recorded, 15% were unaffected, 19% had only their leaves damaged, 25% had some of their leaves and branches damaged, and 41% had all their aerial parts killed. The majority of individuals in the community belonged to frost tolerant species. The regeneration of the stand structure was remarkably rapid; height and canopy cover of the lower stratum recovered completely after five months, and those of the arboreal stratum showed a recovery of about 80% after 11 months. We consider that the frequency and intensity of frosts can maintain more open forms of cerrado vegetation even in sites where both water and nutrient availability could support denser vegetation. It is also probable that some frost-resistant heliophyte species are confined to areas where frosts prevent the development of denser cerrado vegetation. Much of the characteristic floristic composition of the southern region of the cerrado biome may be related to the selection of frost-resistant species. Our study shows, however, that a full complement of cerrado plants is capable of occupying and colonizing frost susceptible sites.

Brando PM; Durigan G

2004-01-01

68

Magnetic susceptibility variation of MSW compost-amended soils: in-situ method for monitoring heavy metal contamination.  

UK PubMed Central (United Kingdom)

Magnetic susceptibility was measured for agricultural soils in Mornag area, Tunisia, where the soils were partly amended by manure or compost obtained from municipal solid waste stabilisation ('MSW compost'). Our study indicates that natural non-treated soils and manure-amended soils are always low in magnetic susceptibility, but MSW compost-amended soils show higher values of this parameter. Actually, the increase of magnetic susceptibility shows a direct correspondence with the increasing of the amount of MSW compost added to the soil. According to the magnetic mineralogical investigation carried out by isothermal remanent magnetisation acquisition technique, higher magnetic susceptibility values are depending on an increase in ferromagnetic components such as either magnetite (beta-Fe3O4) or maghemite (gamma-Fe2O3) particles. The growth in content of these ferromagnetic components corresponds to an increase of the concentration of heavy metals in soils, which means that magnetic susceptibility indirectly indicates the concentration of heavy metals in MSW compost-amended soils.

Yoshida M; Jedidi N; Hamdi H; Ayari F; Hassen A; M'Hiri A

2003-04-01

69

Laboratory-produced sorted patterned ground by repeated frost heaving  

Science.gov (United States)

Sorted patterned ground is ubiquitous where gravelly fine soils experience freeze-thaw cycles, but laboratory models have rarely been successful in reproducing such patterns. Here we report the first result of an attempt to reproduce miniature sorted patterns by repeating needle-ice formation, which simulates frost sorting in regions dominated by diurnal freeze-thaw cycles. The laboratory models (50×50×35 cm) consist of near-saturated volcanic fine soil topped by small stones with varying sizes, SSG (~8 mm), SG (~16 mm), MG (~19 mm) and LG (~26.5 mm), and varying surface coverage (20, 40 and 60%). The stones were white-painted and placed in a grid on the surface. These models were subjected to 10-20 temperature excursions between 10°C and -5°C in 12 hours. The evolution of surface patterns were visually traced by vertical and oblique photogrammetry taken at intervals of 10 minutes. The time series of pictures were compiled to produce animations. In addition, a data logging system continuously monitored vertical soil displacements, soil temperatures and moistures at different depths. All experimental runs displayed needle ice formation (2-3 cm in height) and resulting displacement of stones. Differential frost heave took place between the soil domains and stones, such that the soils tend to heave faster and higher than the stones. The preferential and higher heaving led to outward movements of the soil domains after cycles of frost heave and thaw settlement, and subsequently to concentration of the stones. In plan view, smaller stones (SSG and SG) showed relatively fast (1-2 mm/cycle) and long-lasting (up to 20 cycles) movements. In contrast, larger stones (MG and LG) displaced rapidly (1-2 mm/cycle) in the first 5 cycles, but thereafter they were stabilized. The lowest stone coverage (20%) produced stone islands at horizontal intervals of about 12 cm, whereas higher coverage (40%) resulted in a stone circle-island complex with a mean diameter of 13 cm. The latter geometry appears to represent incipient sorted circles, dimensions of which are comparable to those observed in the field. The experiments imply that needle-ice activity induces frost sorting rapidly, which potentially allows the formation of stone islands and incipient sorted circles within one or a few years, but more regular circles may need hundreds of diurnal frost heave cycles (i.e., decade-to-century time scales).

Yamagishi, Chizuru; Matsuoka, Norikazu

2013-04-01

70

Heavy Metals in Urban Soils of Xuzhou, China: Spatial Distribution and Correlation to Specific Magnetic Susceptibility  

Directory of Open Access Journals (Sweden)

Full Text Available The investigation of the anthropogenic contamination by heavy metals of soils is very important for environmental planning and monitoring in urban areas. In the present study, surface soils (0-20 cm) samples from 167 sampling sites in Xuzhou (China) were collected in 2010 and analyzed for heavy metals including Zn, Pb, Fe, Mn, Cu, Cd, Sr, Ba Cr, Ni and Mo via inductively coupled plasma/mass spectrometry (ICP-MS). Compared with their levels in natural soils of China, these metals investigated exhibited a slight build-up in Xuzhou topsoils. The multivariate statistical analyses including factor analysis (FA) and cluster analysis (CA) were performed. The obtained results enabled the identification of two main groups of metals, discriminating Ni, Mo and Cr from Zn, Pb, Fe, Mn, Cu, Cd, Sr and Ba. Signifcant associations between Pb, Zn, Fe and specific magnetic susceptibility (c) indicated that specific susceptibility can serve as proxies for these metals levels in Xuzhou urban soils.

Xuesong Wang

2013-01-01

71

Removal of sulphur dioxide and sulphates from the atmospheric surface layer during frost formation  

Energy Technology Data Exchange (ETDEWEB)

In order to establish the amount of removal of SO[sub 2] and sulphates from the lowest layer of the atmosphere during frost formation, a field measurement experiment was conducted in January 1990 in the Ravenna area. Frost can bring about removal of particles, gases and hydrosoluble substances. In common with areas of the Po Valley, Ravenna is frequently subjected to atmospheric conditions that can cause frost. During the winter of 1990, clear skies at night, that were associated with high pressure fields, strongly influenced the formation of frost. Close to industrial plants, characterized by wet emission of plumes, this frost has an adverse impact on soil, commonly known as 'chemical snow'. A large number of frost samples, collected in three locations representing typical but different features of the area, (rural, urban and sea front site), were analyzed. Analysis of the data reveals that SO[sub 2] is the major contributor to SO[sub 4][sup 2-] trapped in frost. 20 refs., 7 figs.

Georgiadis, T.; Strocchi, V.; Fortezza, F.; Lucialli, P.; Bonasoni, P.; Giovanelli, G. (FISBAT - C.N.R., Bologna (Italy))

1993-02-01

72

Damage to Norway spruce [Picea abies (L. ) Karst] seedlings caused by a late spring frost  

Energy Technology Data Exchange (ETDEWEB)

On 11 May 1990 night frost occurred in central Sweden. The period prior to the frost was characterized by high temperatures; thus many spruce plantations were at a sensitive stage of bud flushing. Frost damage was recorded in a field trial. The trial was a progeny test with half-sib families of Norway spruce collected in seed orchards, and the seedling were in the beginning of their third growing season. Bud flushing, lignification of the leader, height growth and damage were assessed yearly in the trial. The flushing stage had been recorded one week before the frost. One week after the frost the flushing stage was registered again. The frequency of frost-damaged new shoots was also noted. Interpolation based on the temperature sum was used to estimate the flushing stage in the frost occasion. The results show that the seedlings were most susceptible to frost damages at the time of bud burst, when the tender needle tips emerge from the burst bud scales. At later flushing stages, 5-6 according to a system developed by Krutzsch (1973), which normally are reached 1-2 weeks after bud burst, only about half as much damage was sustained. Differences in hardiness were found between families, compared at the same flushing stage. These differences were not related to the geographical origin of the mother tree. The frequency of damage was higher among seedlings showing slow growth during the previous year than among faster-growing seedlings. No relation between frost hardiness and time of growth cessation was found when seedlings in the same flushing stage were compared. 13 refs, 2 figs, 8 tabs

Hannerz, M.

1994-01-01

73

Frost heave modelling of buried pipelines using non-linear Fourier finite elements  

International Nuclear Information System (INIS)

Numerical analysis of the response of a three-dimensional soil-pipeline system in a freezing environment using non-linear Fourier finite elements was described as an illustration of the effectiveness of this technique in analyzing plasticity problems. Plastic deformations occur when buried pipeline is under the action of non-uniform frost heave. The three-dimensional frost heave which develops over time including elastoplastic deformations of the soil and pipe are computed. The soil heave profile obtained in the numerical analysis was consistent with experimental findings for similar configurations. 8 refs., 8 figs

1998-01-01

74

EVALUATION OF FROST HEAVE ON WASTE TRANSFER LINES WITH SHALLOW DEPTHS IN DST (DOUBLE SHELL TANK) FARMS  

Energy Technology Data Exchange (ETDEWEB)

The purpose of this document is to evaluate the effect of frost heave on waste transfer lines with shallow depths in DST farms. Because of the insulation, well compacted sandy material around waste transfer lines, the type of sandy and gravel soil, and relatively low precipitation at Hanford site, it is concluded that waste transfer lines with one foot of soil covers (sandy cushion material and insulation) are not expected to undergo frost heave damaging effects.

HAQ MA

2009-05-12

75

Photosynthetic responses to frost and excessive light in field-grown Scots pine and Norway spruce  

Energy Technology Data Exchange (ETDEWEB)

In forestry, frost damage has been synonymous with visible damage caused by freezing night temperatures during the growing season. Frequent failure of forest regeneration in frost-prone areas has led to a number of silvicultural techniques intended to reduce plant losses in such areas. Felling leaving shelterwoods, and soil scarification, are methods used by Swedish foresters to mitigate the problem of freezing temperatures in conifer regeneration. These measures result in some improvement of the temperature climate near the ground, but frost still remains one of the major problems for reforestation in frost-prone areas. A better understanding of the processes behind frost related problems is needed to further improve methods for regeneration of frost-prone sites in order to decrease plant losses and thereby costs. This thesis examines how freezing temperatures affect photosynthesis of Scots pine and Norway spruce, with an emphasis on the interaction of low temperature and excess light on field grown seedlings. Photosynthesis was estimated by gas exchange measurements of intact shoots and measurements of chlorophyll fluorescences of detached needles. The results presented imply that both low temperature inhibition and photoinhibition of photosynthesis might be of more importance to survival and growth of conifers than earlier assumed. Photosynthetic performance can be severely reduced after night frost without the occurrence of visible damage. The results indicate that temperature alone cannot explain the development of damage after night frost, but the radiation load during the following days must be considered as well. The reduction of frost injuries often observed in shelterwoods consequently depends both on higher minimum temperatures and lower incident irradiance. 131 refs, 8 figs

Lundmark, T.

1996-05-01

76

Effect of Soil Temperature on Infectivityand Development of Rotylenchulus reniformis on Resistant and Susceptible Soybeans, Glycine max  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The effect o f soil temperature on parasitism and development of Rotylenchulus reniformis on resistant ('Peking' and 'Custer') and susceptible ('Hood' and 'Lee') soybean (Glycine max) cultivars was studied. Soil temperatures of 15, 21.5, 25, 29.5 and 36 C ± 1 C were maintained in temperature tanks i...

Rebois, R. V.

77

[Correlativity study of the distribution of soil magnetic susceptibility and the heavy metal contents in Xi'an City].  

UK PubMed Central (United Kingdom)

The magnetic susceptibility and the concentrations of Co, Cr, Cu, Pb, Sn, Sr and Ba in topsoil samples from Xi'an City were measured to study their spatial distribution and their correlation in this study. The results show that the concentrations of all measured heavy metals are higher than their background values in Cinnamon topsoil, which is the main soil type of Xi'an City. The heavy metals concentrations and the magnetic susceptibility of the studied samples display moderate variance. Co, Cr, Cu, Pb, Sn, Sr and Ba are significantly positively correlated with low-frequency magnetic susceptibility, while are significantly negatively correlated with frequency susceptibility. The spatial distribution of low-frequency magnetic susceptibility is identical with the concentrations of Pb and Cu. However, the spatial variation of frequency magnetic susceptibility is different from the concentrations of Co, Cr and Ba. The pollution assessment results show that the heavy metal pollution in topsoil of Xi'an City is moderate. The spatial contribution of the pollution load index was significantly correlated with the magnetic susceptibility of topsoil in Xi'an City. Therefore, soil magnetic susceptibility can be used as an effective monitoring means for heavy metal pollution in urban soil.

Chen XD; Lu XW; Yang G

2013-03-01

78

Frost Growth and Densification in Laminar Flow Over Flat Surfaces.  

Science.gov (United States)

One-dimensional frost growth and densification in laminar flow over flat surfaces has been theoretically investigated. Improved representations of frost density and effective thermal conductivity applicable to a wide range of frost circumstances have been...

M. Kandula

2011-01-01

79

On Frost’s Colorful Imagery with Profound Implication  

Directory of Open Access Journals (Sweden)

Full Text Available Robert Frost prefers employing common imagery to help express profound ideas. This leads to the deceptive simpleness of his poetry. The understanding of the imagery is crucial to the understanding of his poetry. Through the analysis of the colorful and ordinary imagery world, the poet’s deep thoughts on nature and society is manifested: he finds nature both benevolent and violent; and facing the chaotic and disordered reality, poetry composition can provide a momentary escape for him and enable him to be courageous enough to treat the reality.

Qian Chen

2012-01-01

80

Studies of the depth and duration of ground frost of peat production areas in Sweden and Finland. Studier av tjaeldjup och tjaelvaraktighet paa torvtaekter i Sverige och Finland  

Energy Technology Data Exchange (ETDEWEB)

A careful registration of the depth of the ground frost, snow, water level, and soil temperature, was done during the winter 1985/86, at eight different peat production areas in Sweden. At one of the places, Traeskmyran, a larger registration was carried out, with eleven spots totally. Experiments to influence the thawing speed of the ground frost at peat production areas by melting the snow by different means, was carried out at three peat production areas during the spring 1986. The different materials used were iron oxide, soot and milled peat. The measurements on the test areas indicate that: -the largest part of the ground frost was thawing from the top, -the thawing of ground frost was negligible from the bottom, -the depth of ground frost is dependent on temperature and the depth of snow, -the ground frost can differ more across a strip than along or among different strips, -high groundwater level gives a small decrease of the ground frost depth, -thawing of soil frost, underneath 20 cm of the surface, occurs faster on an area with high groundwater level than an area with low groundwater level, -forced snow melting did not effect the thawing of the ground frost 20 cm below the surface, during the test year. (authors).

Dryler, K.; Frilander, P.; Niittylae, H.; Leinonen, A.

1988-03-01

 
 
 
 
81

Time-domain response of a metal detector to a target buried in soil with frequency-dependent magnetic susceptibility  

Science.gov (United States)

The work reported in this paper is a part of on-going studies to clarify how and to what extent soil electromagnetic properties affect the performance of induction metal detectors widely used in humanitarian demining. This paper studies the specific case of the time-domain response of a small metallic sphere buried in a non-conducting soil half-space with frequency-dependent complex magnetic susceptibility. The sphere is chosen as a simple prototype for the small metal parts in low-metal landmines, while soil with dispersive magnetic susceptibility is a good model for some soils that are known to adversely affect the performance of metal detectors. The included analysis and computations extend previous work which has been done mostly in the frequency domain. Approximate theoretical expressions for weakly magnetic soils are found to fit the experimental data very well, which allowed the estimation of soil model parameters, albeit in an ad hoc manner. Soil signal is found to exceed target signal (due to an aluminum sphere of radius 0.0127 m) in many cases, even for the weakly magnetic Cambodian laterite used in the experiments. How deep a buried target is detected depends on many other factors in addition to the relative strength of soil and target signals. A general statement cannot thus be made regarding detectability of a target in soil based on the presented results. However, computational results complemented with experimental data extend the understanding of the effect that soil has on metal detectors.

Das, Y.

2006-06-01

82

Effects of frost on wildflowers: an unexpected consequence of climate change--image 14 of 22  

Science.gov (United States)

A female broad-tailed hummingbird (Selasphorus platycercus) in Colorado visiting tall larkspur (Delphinium barbeyi). The hummingbirds migrate north from Mexico each spring. Larkspurs serve as an important food source for them and for bumble bees. But larkspurs are also susceptible to frost, impacting the species that feed on them.

Inouye, David

2012-01-04

83

FROST BREAKFAST CEREAL AND PRODUCTION METHOD THEREFOR  

UK PubMed Central (United Kingdom)

Frost breakfast cereal containing 0.1 wt% or more of catechins relative to the dry weight of breakfast cereal, wherein the proportion of the solids other than the saccharides in a coating material of the frost breakfast cereal is 1 wt% or more, and the proportion of catechins in the solids other than the saccharides is 40 wt% or more.

MITOBE HIROYUKI

84

Unilateral frosted branch angiitis with vitreous haemorrhage.  

Directory of Open Access Journals (Sweden)

Full Text Available Idiopathic retinal frosted branch angiitis is a rare bilateral condition and presents with an acute reduction of vision. Unilateral affection is rare. We report an unusual case of unilateral frosted branch angiitis where the patient developed total vitreous haemorrhage.

Agrawal S; Agrawal J; Agrawal T

2001-01-01

85

Restoring sedges and mosses into frost heaving iron fens, San Juan Mountains, Colorado  

Directory of Open Access Journals (Sweden)

Full Text Available Rare iron fens in the San Juan Mountains of Colorado are frequently in poor condition due to mining, roads and ditches, which have left much of the fen completely bare of vegetation. Natural revegetation is slow to occur in the bare areas because of severe frost heave in the cold mountain climate. Therefore, experimental revegetation plots were conducted in a factorial design with mulching and no mulching, crossed with moss diaspores, sedge transplants, and moss and sedge combined. Mulching influenced surface soil temperatures by reducing the midday highs and increasing the night-time lows, which decreased the frequency and amount of frost heave. Peat moisture also modified frost heave, with the greatest frost heaving occurring near 75 % peat moisture content (water table 10–20 cm below the surface) and the least when soils were either wetter or drier. Moss survival was dependent on mulch, with no moss surviving in plots without mulch. Mulching also increased sedge transplant survival. In summary, mulching significantly increased the success of vegetation restoration efforts for frost heave areas in mountain fens.

R.A. Chimner

2011-01-01

86

Neural Network-Based Model for Landslide Susceptibility and Soil Longitudinal Profile Analyses : two case studies  

DEFF Research Database (Denmark)

The purpose of this study was to create an empirical model for assessing the landslide risk potential at Savadkouh Azad University, which is located in the rural surroundings of Savadkouh, about 5 km from the city of Pol-Sefid in northern Iran. The soil longitudinal profile of the city of Babol, located 25 km from the Caspian Sea, also was predicted with an artificial neural network (ANN). A multilayer perceptron neural network model was applied to the landslide area and was used to analyze specific elements in the study area that contributed to previous landsliding events. The ANN models were trained with geotechnical data obtained from an investigation of the study area. The quality of the modeling was improved further by the application of some controlling techniques involved in ANN. The observed >90% overall accuracy produced by the ANN technique in both cases is promising for future studies in landslide susceptibility zonation.

Farrokhzad, F.; Barari, Amin

2011-01-01

87

An experimental study of frost formation on the horizontal cylinder  

Energy Technology Data Exchange (ETDEWEB)

In this study, thickness, density and effective thermal conductivity of frost forming on the horizontal cylinder were measured with various air temperature and humidity. Reynolds number and temperature of cooling surface are controlled 17300 and -15 deg.C respectively. In each case of air temperature 5 deg.C, 10 deg.C, 15 deg.C, varying absolute humidity, experiments were executed. In measuring frost surface temperature and thickness of frost layer, infrared thermocouples and CCD camera were used. Frost was gathered from cylinder to measure mass of frost layer. Experimental data showed that the thickness and effective thermal conductivity of the frost layer increase with respect to time. Thickness of frost layer increase with humidity increasing, and density of frost layer increase with air temperature rising. Frost growth with air temperature and density of frost layer with humidity are affected by whether dew point is below or above freezing point. (author). 11 refs., 10 figs.

Baik, S.J.; Lee, Y.B. [Seoul National University Graduate School, Seoul (Korea); Ro, S.T. [Seoul National University, Seoul (Korea)

2000-04-01

88

Evaluation of Frost Heave on Waste Transfer Lines with Shallow Depths in DST Farms.  

Science.gov (United States)

The purpose of this document is to evaluate the effect of frost heave on waste transfer lines with shallow depths in DST farms. Because of the insulation, and well compacted sandy material around waste transfer lines, the type of sandy and gravel soil, an...

M. A. Haq

2009-01-01

89

Evaluation of soil treatments for control of Meloidogyne Arenaria in caladium tubers (Caladium × Hortulanum) and nematode susceptibility of selected cultivars  

Science.gov (United States)

Field and greenhouse studies were conducted to assess the effectiveness of soil fumigants for control of Meloidogyne arenaria on harvested caladium (Caladium × hortulanum) tubers, to determine the susceptibility of five commonly grown caladium cultivars to M. arenaria, and to evaluate effects of fum...

90

Future Bloom and Blossom Frost Risk for Malus domestica Considering Climate Model and Impact Model Uncertainties  

Science.gov (United States)

The future bloom and risk of blossom frosts for Malus domestica were projected using regional climate realizations and phenological (?=?impact) models. As climate impact projections are susceptible to uncertainties of climate and impact models and model concatenation, the significant horizon of the climate impact signal was analyzed by applying 7 impact models, including two new developments, on 13 climate realizations of the IPCC emission scenario A1B. Advancement of phenophases and a decrease in blossom frost risk for Lower Saxony (Germany) for early and late ripeners was determined by six out of seven phenological models. Single model/single grid point time series of bloom showed significant trends by 2021–2050 compared to 1971–2000, whereas the joint signal of all climate and impact models did not stabilize until 2043. Regarding blossom frost risk, joint projection variability exceeded the projected signal. Thus, blossom frost risk cannot be stated to be lower by the end of the 21st century despite a negative trend. As a consequence it is however unlikely to increase. Uncertainty of temperature, blooming date and blossom frost risk projection reached a minimum at 2078–2087. The projected phenophases advanced by 5.5 d K?1, showing partial compensation of delayed fulfillment of the winter chill requirement and faster completion of the following forcing phase in spring. Finally, phenological model performance was improved by considering the length of day.

Hoffmann, Holger; Rath, Thomas

2013-01-01

91

Tendency of mining discards to frost expansion  

Energy Technology Data Exchange (ETDEWEB)

Considerable frost heave may occur in mining discards in which the proportion of grains below 0.1 mm , 0.5 mm or 2 mm constitutes 15%, 30% or 60% respectively. Removal of the smaller fractions (in particular of grains below 0.1 mm) largely reduces their frost heaving tendency. Greatest heaving occurred at a freezing temperature of -5C and -10 C. Greatest intensity of development of this process was found at -20 C.

Soczawa, A.

1981-01-01

92

Condensation and frost formation in heat exchangers  

Energy Technology Data Exchange (ETDEWEB)

The occurence of condensation and of frost formation are considered for air to heat exchangers with emphasis on how such occurrences would affect the performance of such heat exchangers when they are used in ventilating applications. The formulations which predict performance are developed for parallel, counter flow and cross flow with either formation or condensation, and for condensation the consequences for evaporation of condensate and of the effect of longitudinal conduction in the walls of the exchanger are also considered. For the prediction of the exchanger performance with frost formation there must be specified the growth of the frost layer with time and existing theories for this growth are examined, a new method of calculation of the growth is presented and this is shown to give results for the growth that are in accord with available experimental evidence. This new theory for the growth of a frost layer is used to predict the performance of a parallel flow exchanger under conditions in which frost formation occurs, by successively applying the steady state performance calculation for time increments over which the frost layer build-up is calculated for these time increments. The calculation of counter flow exchanger performance by this method, while feasible, is so time consuming that only the general aspects of the calculation are considered.

Rostami, A.A.

1982-01-01

93

Condensation and frost formation in heat exchangers  

International Nuclear Information System (INIS)

The occurence of condensation and of frost formation are considered for air to heat exchangers with emphasis on how such occurrences would affect the performance of such heat exchangers when they are used in ventilating applications. The formulations which predict performance are developed for parallel, counter flow and cross flow with either formation or condensation, and for condensation the consequences for evaporation of condensate and of the effect of longitudinal conduction in the walls of the exchanger are also considered. For the prediction of the exchanger performance with frost formation there must be specified the growth of the frost layer with time and existing theories for this growth are examined, a new method of calculation of the growth is presented and this is shown to give results for the growth that are in accord with available experimental evidence. This new theory for the growth of a frost layer is used to predict the performance of a parallel flow exchanger under conditions in which frost formation occurs, by successively applying the steady state performance calculation for time increments over which the frost layer build-up is calculated for these time increments. The calculation of counter flow exchanger performance by this method, while feasible, is so time consuming that only the general aspects of the calculation are considered

1982-01-01

94

Frost sensitivity of desulphurisation by-products. Laboratory investigation of hardened dry product and dry product in pellet form  

Energy Technology Data Exchange (ETDEWEB)

To investigate the frost susceptibility of desulphurization products, and experimental set-up has been developed. This consists of a rectangular sample with dimensions 80 x 70 x 30 cm, positioned in a controlled temperature field between two heat reservoirs. The heat reservoirs are connected with two automatically controlled cooling baths with an effective temperature range between -15 and +30 deg. C. Insulation assures a uniform temperature gradient through the sample, with no significant side friction effects. The arrangement is equipped with displacement transducers for measurement of any frost heaves that develop. Temperature variations within the sample are monitored by two series of thermo-elements with electronic data logging. With the use of this apparatus, hardened, compacted desulphurization product, as well as pelletized samples have been examined through long-term freezing experiments. Detailed results and graphic analysis are presented and evaluated. Unsaturated samples with no addition of water show no frost heaving. With addition and absorptions of water, hardened desulphurization product must be considered low to moderately frost susceptible, with a freezing rate of 2 mm/24 hr and greater than 20 mm of heaving after 250 hours freezing. Pellets can be considered as non-frost susceptible after international criteria. (author).

Foged, N.; Foged, N.; Joens, E. (eds.)

1989-02-01

95

Effective thermal conductivity of frost during the crystal growth period  

Energy Technology Data Exchange (ETDEWEB)

An effective frost thermal conductivity for the crystal growth period of frost formation was developed based on a simple model consisting of cylindrical frost columns surrounded by moist air. Being closely related to the frost layer density, the thermal conductivity of frost layer is found to be affected by the vapor diffusion inside the frost layer as well. The density of frost columns, on the other hand, depends on the sublimation temperature of ice crystals and the humidity ratio of air, therefore, the whole process of frost formation and the thermal conductivity of frost layer, in particular, is shown to depend on the controlling temperatures, i.e. plate temperature, air temperature, and air humidity ratio. (Author)

Sahin, A.Z. [King Fahd University of Petroleum Minerals, Dhahran (Saudi Arabia). Dept. of Mechanical Engineering

2000-02-01

96

Suscetibilidade de dois tipos de solo à compactação Compaction susceptibility of two classes of soil  

Directory of Open Access Journals (Sweden)

Full Text Available Com vistas ao aumento da produção agrícola, optou-se no Brasil, pelo acréscimo de área cultivada; para tal o uso indiscriminado da motomecanização mostrou-se eficiente em um primeiro momento, porém acarretando problemas à física do solo no decorrer dos anos. Paralelamente, práticas conservacionistas se fazem presentes, vide semeadura sob a palha (Plantio Direto), uma realidade no sul do Brasil. Sendo assim, avaliou-se a suscetibilidade de compactação de dois tipos de solo, ambos com sistema de semeadura sob a palha. Para dimensionar a suscetibilidade a compactação, utilizou-se ensaio de Proctor. Os solos foram ensaiados com e sem a presença de matéria orgânica livre. Os resultados demonstraram que para o Cambissolo, textura média, não houve diferença nos valores que representam a suscetibilidade, enquanto no Latossolo Vermelho, textura argilosa, não houve diferença entre a máxima densidade aparente, porém houve diferença significativa no conteúdo de água para a máxima densidade, o mesmo alterou-se de 0,249 g g-1 no ponto de máxima compactação no ensaio sem a presença de matéria orgânica livre, para 0,283 g g-1 no ponto de máxima compactação, quando da presença da matéria orgânica livre.For increasing agricultural production, Brazil opted to enlarge the cultivated area, and indiscriminate mechanization was efficient at the first moment, although it altered adversely the soil properties with the passage of time. At the same time, conservation practices, like the direct sowing under the straw (No Tillage) were adopted which is a reality in Southern Brazil. Considering this, the susceptibility for compaction of two classes of soil was evaluated under no tillage system, with and without free organic matter. The Proctor test was used to measure the degree of compaction. The results of a medium texture Cambissol showed there was no difference in susceptibility for compaction. The clay textured Red Latossol, showed no difference in the maximum apparent density, although there was significant difference in water content at maximum density. The values altered from 0.249 g g-1, at a maximum compaction point without free organic matter to 0.283 g g-1 with free organic matter.

Pedro H. Weirich Neto; André L. T. da Rosa; Jaime A. Gomes

2002-01-01

97

Moisture performance analysis of EPS frost insulation  

Energy Technology Data Exchange (ETDEWEB)

A horizontal layer of expanded polystyrene foam (EPS) is widely used as a frost insulation of building foundations in the Nordic countries. The performance properties of the insulation depend strongly on the moisture level of the material. Experimental methods are needed to produce samples for testing the material properties in realistic moisture conditions. The objective was to analyze the moisture loads and the wetting mechanisms of horizontal EPS frost insulation. Typical wetting tests, water immersion and diffusive water vapor absorption tests, were studied and the results were compared with the data from site investigations. Usually these tests give higher moisture contents of EPS than what are detected in drained frost insulation applications. Also the effect of different parameters, like the immersion depth and temperature gradient were studied. Special attention was paid to study the effect of diffusion on the wetting process. Numerical simulation showed that under real working conditions the long period diffusive moisture absorption in EPS frost insulation remained lower than 1% Vol. Moisture performance was determined experimentally as a function of the distance between the insulation and the free water level in the ground. The main moisture loads and the principles for good moisture performance of frost insulation are presented.

Ojanen, T.; Kokko, E.

1997-11-01

98

Frost halos from supercooled water droplets.  

UK PubMed Central (United Kingdom)

Water freezing on solid surfaces is ubiquitous in nature. Even though icing/frosting impairs the performance and safety in many processes, its mechanism remains inadequately understood. Changing atmospheric conditions, surface properties, the complexity of icing physics, and the unorthodox behavior of water are the primary factors that make icing and frost formation intriguing and difficult to predict. In addition to its unquestioned scientific and practical importance, unraveling the frosting mechanism under different conditions is a prerequisite to develop "icephobic" surfaces, which may avoid ice formation and contamination. In this work we demonstrate that evaporation from a freezing supercooled sessile droplet, which starts explosively due to the sudden latent heat released upon recalescent freezing, generates a condensation halo around the droplet, which crystallizes and drastically affects the surface behavior. The process involves simultaneous multiple phase transitions and may also spread icing by initiating sequential freezing of neighboring droplets in the form of a domino effect and frost propagation. Experiments under controlled humidity conditions using substrates differing up to three orders of magnitude in thermal conductivity establish that a delicate balance between heat diffusion and vapor transport determines the final expanse of the frozen condensate halo, which, in turn, controls frost formation and propagation.

Jung S; Tiwari MK; Poulikakos D

2012-10-01

99

How endangered is sexual reproduction of high-mountain plants by summer frosts? Frost resistance, frequency of frost events and risk assessment.  

UK PubMed Central (United Kingdom)

In temperate-zone mountains, summer frosts usually occur during unpredictable cold spells with snow-falls. Earlier studies have shown that vegetative aboveground organs of most high-mountain plants tolerate extracellular ice in the active state. However, little is known about the impact of frost on reproductive development and reproductive success. In common plant species from the European Alps (Cerastium uniflorum, Loiseleuria procumbens, Ranunculus glacialis, Rhododendron ferrugineum, Saxifraga bryoides, S. moschata, S. caesia), differing in growth form, altitudinal distribution and phenology, frost resistance of reproductive and vegetative shoots was assessed in different reproductive stages. Intact plants were exposed to simulated night frosts between -2 and -14 °C in temperature-controlled freezers. Nucleation temperatures, freezing damage and subsequent reproductive success (fruit and seed set, seed germination) were determined. During all reproductive stages, reproductive shoots were significantly less frost resistant than vegetative shoots (mean difference for LT50 -4.2 ± 2.7 K). In most species, reproductive shoots were ice tolerant before bolting and during fruiting (mean LT50 -7 and -5.7 °C), but were ice sensitive during bolting and anthesis (mean LT50 around -4 °C). Only R. glacialis remained ice tolerant during all reproductive stages. Frost injury in reproductive shoots usually led to full fruit loss. Reproductive success of frost-treated but undamaged shoots did not differ significantly from control values. Assessing the frost damage risk on the basis of summer frost frequency and frost resistance shows that, in the alpine zone, low-statured species are rarely endangered as long as they are protected by snow. The situation is different in the subnival and nival zone, where frost-sensitive reproductive shoots may become frost damaged even when covered by snow. Unprotected individuals are at high risk of suffering from frost damage, particularly at higher elevations. It appears that ice tolerance in reproductive structures is an advantage but not an absolute precondition for colonizing high altitudes with frequent frost events.

Ladinig U; Hacker J; Neuner G; Wagner J

2013-03-01

100

How endangered is sexual reproduction of high-mountain plants by summer frosts? Frost resistance, frequency of frost events and risk assessment.  

Science.gov (United States)

In temperate-zone mountains, summer frosts usually occur during unpredictable cold spells with snow-falls. Earlier studies have shown that vegetative aboveground organs of most high-mountain plants tolerate extracellular ice in the active state. However, little is known about the impact of frost on reproductive development and reproductive success. In common plant species from the European Alps (Cerastium uniflorum, Loiseleuria procumbens, Ranunculus glacialis, Rhododendron ferrugineum, Saxifraga bryoides, S. moschata, S. caesia), differing in growth form, altitudinal distribution and phenology, frost resistance of reproductive and vegetative shoots was assessed in different reproductive stages. Intact plants were exposed to simulated night frosts between -2 and -14 °C in temperature-controlled freezers. Nucleation temperatures, freezing damage and subsequent reproductive success (fruit and seed set, seed germination) were determined. During all reproductive stages, reproductive shoots were significantly less frost resistant than vegetative shoots (mean difference for LT50 -4.2 ± 2.7 K). In most species, reproductive shoots were ice tolerant before bolting and during fruiting (mean LT50 -7 and -5.7 °C), but were ice sensitive during bolting and anthesis (mean LT50 around -4 °C). Only R. glacialis remained ice tolerant during all reproductive stages. Frost injury in reproductive shoots usually led to full fruit loss. Reproductive success of frost-treated but undamaged shoots did not differ significantly from control values. Assessing the frost damage risk on the basis of summer frost frequency and frost resistance shows that, in the alpine zone, low-statured species are rarely endangered as long as they are protected by snow. The situation is different in the subnival and nival zone, where frost-sensitive reproductive shoots may become frost damaged even when covered by snow. Unprotected individuals are at high risk of suffering from frost damage, particularly at higher elevations. It appears that ice tolerance in reproductive structures is an advantage but not an absolute precondition for colonizing high altitudes with frequent frost events. PMID:23386042

Ladinig, Ursula; Hacker, Jürgen; Neuner, Gilbert; Wagner, Johanna

2013-02-06

 
 
 
 
101

Frost events in past years as possible stress factors  

Energy Technology Data Exchange (ETDEWEB)

Frost events in past years in Bavaria are analysed under consideration of possible frost damages in forests. The abrupt decrease of air temperature at turn of the year 1978 and extreme cold in January and February 1985 are discussed as examples for extreme cold periods in winter. Late frost in Bavaria in the period 1953 to 1986 is analysed by use of frequency distribution of days with late frost and its intensity. Late frost events in April and May 1981 are discussed as example for a single late frost period. Using the same method early frost in Bavaria in the period 1953 to 1985 is investigated. As case study early frost in September and October 1972 is analysed.

Mayer, H.

1987-03-01

102

Design of UMTRA covers to mitigate the effect of frost penetration  

Energy Technology Data Exchange (ETDEWEB)

The Uranium Mill Tailings Remedial Action (UMTRA) Project, contracted by the US Department of Energy (DOE), requires construction of disposal cells for residual radioactive materials from abandoned uranium mill tailings. A disposal cell consists of contaminated material placed within a stabilized embankment with a top cover. The embankment and cover should be effective for up to 1000 years, to the extent reasonably achievable, and in any case for at least 200 years. The embankment cover usually consists of a radon/infiltration barrier, a frost barrier and erosion protection layer consisting of bedding and riprap layers. The radon/infiltration barrier and frost barrier are two important elements of the cover systems. A radon/infiltration barrier is designed to reduce the radon emissions from the contaminated materials and to limit the surface water infiltration into the contaminated material. However, a radon/infiltration barrier has to be protected from repeated freeze-thaw cycles to prevent an increase in permeability. Frost penetration depth is site specific and depends on local climatic conditions and soil properties of the cover system. However, placing a frost barrier is not only very costly but also reduces the disposal capacity of the embankment. Recent laboratory test results indicate that freeze-thaw cycles do not significantly effect the permeability of compacted sand-bentonite mixtures. Therefore, radon/infiltration barriers using sand-bentonite mixtures may not require frost barriers for protection against the effects of freeze-thaw. In this paper the design of UMTRA covers is briefly explained; the criteria to determine a 200 year freeze event, and the frost penetration depth are discussed. The results of freeze-thaw permeability tests on compacted clay and sand-bentonite mixtures are also presented.

Banani, A.M.; Claire, R.F.

1994-03-01

103

Frost resistance of fibre reinforced concrete structures  

DEFF Research Database (Denmark)

Frost resistance of fibre reinforced concrete with 2.5-4.2% air and 6-9% air (% by volume in fresh concrete) casted in the laboratory and in-situ is compared. Steel fibres with hooked ends (ZP, length 30 mm) and polypropylene fibres (PP, CS, length 12 mm) are applied. It is shown that· addition of 0.4-1% by volume of fibres cannot replace air entrainment in order to secure a frost resistant concrete; the minimum amount of air needed to make the concrete frost resistant is not changed when adding fibres· the amount of air entrainment must be increased when fibres are added to establish the same amount of air pores as in the corresponding concrete without fibres

Hansen, Ernst Jan De Place

1999-01-01

104

Rapid frost weathering and its potential role as a periglacial buzzsaw  

Science.gov (United States)

Icy Bay, in the Chugach-St.Elias mountains of southern Alaska, provides an excellent opportunity to 1) document exceptionally rapid breakdown of cobbles on surfaces recently exposed by glacial retreat, 2) examine frost-induced breakdown in light of recent advances in theory, and 3) explore the potential role of periglacial processes in limiting the height of mountain ranges. The latter adds to the current interest in the interactions between topography, tectonics and climate, and in particular, the so-called glacial buzzsaw (Egholm, et al. 2009. Nature, 460, p 884; doi:10.1038/nature08263). This is the notion that the growth of mountains is curtailed by erosion and related effects of glaciers with little or no dependence on the factors that are generally thought to control the height of mountains; height increases with the elevation of the snow line, with little or no influence of uplift and exhumation rates, rock type, and precipitation. A well-documented retreat of tidewater glaciers in Icy Bay has resulted in a succession of outwash surfaces on which cobbles of diverse lithology were exposed to atmospheric conditions sequentially. Following deposition, initial breakdown rates were determined for each of four distinct lithologies: siltstone, sandstone, greenschist, and granite/gneiss. These rates decrease to negligible values after 10-15 years of exposure. Breakdown is significantly enhanced adjacent to the current shoreline with the fraction of surface cobbles fractured after 30 years ranging from 20% for granite/gneiss to 90% for siltstone. Theoretical considerations suggest that the susceptibility of a rock type to frost weathering is dictated by its specific surface area and resistance to fracture. These parameters define a threshold zone for frost weathering specific to ambient thermal and moisture conditions in Icy Bay, a conclusion substantiated by independent experimental evidence. This result, coupled with the fact that this and other studies have shown enhanced rock breakdown under relatively mild climatic conditions, suggests the importance of unfrozen water migration in frost weathering under natural conditions and a significantly greater spatial importance of frost weathering than previously recognized. The rate of frost weathering should be maximized for temperatures between -3 to -10°C and in the presence of abundant moisture. These conditions ought to define an elevation interval in mountainous landscapes most conducive to frost weathering. Climatic fluctuations ought to drive large altitudinal changes in this interval causing variations in affected land area. Frost weathering appears to be significantly faster than other subaerial weathering mechanisms, and probably contributes significantly to the rapid exhumation documented in the Icy Bay region (Berger, A.L., et al. 2008. Nature Geoscience,1, 793-802.)

Hallet, Bernard; Roche, James

2010-05-01

105

Frost formation on a horizontal cylinder with free convection  

Energy Technology Data Exchange (ETDEWEB)

Formation of frost on piping is of interest in the study of heat pump systems and refrigeration equipment. An experimental and analytical study of frost formation on a cooled horizontal cylinder with free convection in ambient air was undertaken. Experiments were conducted using two cylinders of different diameter. The surface temperature of the cylinder was controlled by passing a liquid from a constant temperature bath through the cylinder. In most of the experiments, the cylinder surface temperature was changed during the experiment. The environmental parameters, the temperature of the cylinder surface, the frost weight, and the frost thickness were measured periodically. The physical state of the frost surface was also observed. Based on the experimental data, a correlation for mass transfer was deduced. A model for the frost formation based on the mass transfer correlation was also developed. The model was used to simulate frost formation under the same environmental conditions as those existing in the experiments. The model was found to give a good prediction of the frost mass, frost thickness, frost density, and frost surface temperature variations with time. A computer program listing for the frost formation model is included. 35 refs., 107 figs., 1 tab.

Chen Jian.

1994-02-01

106

Frost protection of water-tube batteries; Frostsikring av vannbatterier  

Energy Technology Data Exchange (ETDEWEB)

The need for a good frost protection system is evident. Many circumstances have an impact on the protection. They all influence the time it takes to cool the battery, which increases the risk of frost cracking. The article describes a new frost protection system introduced by Cova AS with improved protection compared to previous systems.

Apeland, Terje Kaare

2002-07-01

107

Modelling apple flower and fruit damage to frost  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Good quality apples are grown in relatively cold areas. However, frost frequently causes damage to flowers and small fruits. When the percentage of frost damage losses is higher than the thinning requirement of the cultivar, production is reduced. In addition to reducing yield, frost damage to the s...

Abreu, J.P. Melo e; Ribeiro, A.C.; Snyder, R.L.

108

Effect of Soil Temperature on Infectivity and Development of Rotylenchulus reniformis on Resistant and Susceptible Soybeans, Glycine max.  

UK PubMed Central (United Kingdom)

The effect o f soil temperature on parasitism and development of Rotylenchulus reniformis on resistant ('Peking' and 'Custer') and susceptible ('Hood' and 'Lee') soybean (Glycine max) cultivars was studied. Soil temperatures of 15, 21.5, 25, 29.5 and 36 C +/- 1 C were maintained in temperature tanks in a greenhouse. R. reniformis developed best at 25 and 29.5 C. The female life cycle can be completed within 19 days after inoculation under favorable conditions at 29.5 C. Plant root growth was best at 21.5 C. During a 27-day period, no egg masses were present on nematodes feeding on roots grown at 15 and 36 C. Egg masses developed on Hood but not on Lee when nematodes were introduced into soil and maintained at 29.5 C for 2 days before raising the temperature to 36 C.

Rebois RV

1973-01-01

109

Fatores abióticos envolvidos na tolerância de trigo à geada Abiotic factors involved in wheat tolerance to frost  

Directory of Open Access Journals (Sweden)

Full Text Available O objetivo deste trabalho foi avaliar a influência da aclimatação, da intensidade de geada e da disponibilidade hídrica sobre os danos causados pela geada em trigo. Os experimentos foram conduzidos em telados, com trigo cultivado em vasos. A aclimatação e a incidência de geada foram simuladas em câmaras de crescimento. Os fatores abióticos avaliados foram: regimes de aclimatação (com e sem); gradiente de temperatura (2, -2, -4 e -7°C); e variação de disponibilidade hídrica no solo, antes da geada (9, 6, 3 e 1 dia sem irrigação). Todos os fatores foram avaliados no afilhamento, alongamento e espigamento das cultivares: BR-18 Terena, mais tolerante à geada; e BRS 194, menos tolerante. As variáveis avaliadas foram: grau de queima de folhas, sete dias após a geada; massa de matéria seca total; e massa de grãos. A aclimatação do trigo, antes da geada, diminuiu os danos provocados antes do espigamento, e resultou em menor queima de folhas e maior rendimento de grãos. A temperatura de -7°C, no espigamento, resultou em falha na produção de grãos de ambas as cultivares; e os prejuízos com geada foram menores nas plantas com nove dias sem irrigação. As condições anteriores à ocorrência de geada têm influência sobre os danos provocados por ela.The objective of this work was to evaluate the influence of acclimatization, frost intensity and soil water availability on damage caused by frost on wheat. The experiments were carried out in screen house conditions. The wheat plants were grown in pots. The acclimatization and frost incidence were simulated in a growth chamber. The abiotic factors evaluated were: acclimatization regimes (with and without); temperature gradient (2, -2, -4 and -7°C) and variation of soil water availability prior to frost incidence (9, 6, 3 and 1 day without irrigation). All factors were evaluated at tillering, stem elongation and heading stage on wheat cultivars BR-18 Terena, more tolerant to frost, and BRS 194, less tolerant. The response variables were: degree of leaf scorching symptoms at 7 days after frost; total dry weight; and grain weight. The acclimatization, before frost, decreased the damage caused on wheat heading stage, which resulted in less leaf scorching symptoms and higher grain yield. Temperature of -7°C, at heading stage, resulted in grain set failure in both cultivars; and frost damage was lower in plants with nine days without irrigation. Prevailing conditions before frost influence frost damage.

Eunice Portela da Silva; Gilberto Rocca da Cunha; João Leonardo Fernandes Pires; Genei Antonio Dalmago; Aldemir Pasinato

2008-01-01

110

Increased susceptibility to bacterial spot of peach trees growing in soil infested with Criconemella xenoplax.  

UK PubMed Central (United Kingdom)

Young Suwanee peach trees were planted in soil infested or not infested with the nematode Criconemella xenoplax. Five months after soil infestation, the leaves were inoculated with Xanthomonas campestris pv. pruni to measure the influence of nematode infestation on bacterial spot development. Bacterial spot lesions in inoculated leaves were more numerous and covered a greater leaf surface area for trees growing in nematode-infested soil than for those in noninfested soil. When the trees were growing in nematode-infested soil, the leaf area diseased was slightly greater on trees in nonsteamed field soil than in soil treated with aerated steam (57 to 62 degrees C for 75 min) prior to infestation with C. xenoplax. Results indicate that bacterial spot damage may become more severe on peach trees if the soil is infested with C. xenoplax than when nematodes have been suppressed.

Shepard DP; Zehr EI; Bridges WC

1999-10-01

111

Frost Heave Control with Buried Insulation.  

Science.gov (United States)

To investigate the effectiveness of extruded insulation panels in the mitigation of frost heave problems, two sites were selected: SH 40 at Rabbit Ears Pass with an elevation of 9,000 feet and I-70 east of Eisenhower Tunnel at an elevation of 10,000 feet....

A. Ardani

1987-01-01

112

Clipping corn following early-season frost.  

UK PubMed Central (United Kingdom)

Regrowing corn (Zea mays L.) plants often develop tied, twisted, or bowed whorls due to growth obstruction by dead leaf tissue, following early season frost damage that kills aboveground foliage but not the growing point. Field studies were conducted in Wisconsin in 1988 after a natural frost to evaluate the effect of postfrost clipping, within 4 d to remove dead tissue, or after 8 to 12 d to unravel tied whorls, on subsequent growth and grain yield. Clipping studies were conducted in Columbia County following a 25 May frost when corn was at the V3 stage, and at two sites in Trempealeau County following a 9 June frost when corn was at V6 (Site 1) and V5 (Site 2) stages. At the Columbia County site, clipping at 4 in. or manually unraveling tied whorls 8 d postfrost did not alter plant survival or grain yield compared to untreated plants. Plant survival and grain yield were also unaffected at Trempealeau County Site 1 by clipping 4 d postfrost at either 4 or 5 in., or 12 d postfrost at 10 in., compared to not clipping. At Trempealeau County Site 2, clipping 4 d postfrost at 4 in. increased grain yield 40% compared to not clipping (99 vs. 69 bu/acre), while clipping 4 d postfrost at 2 in., increased plant mortality and decreased yield 30% (48 vs. 69 bu/acre). At this site, clipping at 8 in., 12 d postfrost resulted in levels of plant survival and grain yield similar to those where plants were not clipped. These results indicate that the risk of further damage due to clipping following early season frost is minimal, provided that clipping height is > 1 in. above the growing point. Clipping may increase grain yield in some cases. More studies of corn response to postfrost clipping under diverse conditions are needed.

Carter PR

1990-07-01

113

AVALIAÇÃO DA SUSCEPTIBILIDADE DE SOLOS GNAISSICOS À EROSÃO SUBSUPERFICIAL / Evaluation of piping erosion susceptibility in gnaissic soils  

Directory of Open Access Journals (Sweden)

Full Text Available The basement rock areas of the Maracujá hydrographic basin show great incidence of hugegullies. This work aims to investigate the influence of the underground erosive processes inthe evolution of these features and to understand how the mineralogical and textural factorscould affect soil erodibility, specially of the saprolites, since the lateric soils of this basin aremore resistant to erosion. So, basic characterization and erodibility essays were carried out in representative soil samples. Soil susceptibility to piping and seepage erosion were investigatedthrough current and modified pin-hole-essays. Laboratory physical models were used in orderto observe these and other possible underground erosion mechanisms, especially the slides.However, piping erosion only occurs in the unsaturated portion of gully slopes, provoked bythe concentration of superficial water, since pipes are not stable under total saturation, whentheir roofs tend to collapse, because of the low cohesion of these saprolites. In the other hand,slumps are very common in the saturated portion of gullies, affecting saprolites even in smalland low declivity slopes.

Fernando Morais; Luis Almeida Prado Bacellar; Frederico Garcia Sobreira

2007-01-01

114

Local variation of frost layer thickness and morphology  

Energy Technology Data Exchange (ETDEWEB)

Frosting is an important phenomenon encountered in the cryogenic industries in connection with gas coolers, refrigerators, heat pumps, etc. It may adversely affect the performances of those devices. This paper experimentally studied the local frost formation process on a cold surface with natural airflows or forced airflows over it. The frost layer thickness was found to increase stepwise during the frost formation process. This increase pattern was ever indicated only by one literature. The literature attributed the pattern to the melting of frost crystals at the frost surface. However, present observation of the morphology of the frost layer surface suggested that the growth of water drops or ice particles at the initial period caused the first slowly increasing of the frost layer thickness; the following growth of acerose-shaped ice crystals caused the rapidly increasing of the frost layer thickness; thereafter, the column-shaped ice crystals on the surface grew in its length and radius alternatively, which caused the frost layer thickness increasing rapidly and slowly alternatively. (authors)

Qu, Kaiyang; Komori, Satoru [Department of Mechanical Engineering, Kyoto University, Kyoto 606-8501 (Japan); Jiang, Yi [Department of Building Science, School of Architecture, Tsinghua University, Beijing 100084 (China)

2006-02-15

115

Development and application of a forecasting system to avoid spring frost damage in chiana valley  

Directory of Open Access Journals (Sweden)

Full Text Available Late frost is one of the more serious adversity for Italian agriculture. Several methods have been developed to protect cultivations, but their application results particularly effective (also from an economic point of view) only if supported by forecasting systems during the more susceptible period of the year. On these basis a forecasting system of late frost in Val di Chiana (an area in central Italy mainly cultivated with cereals and high quality fruits) was developed. The system consists in an empirical model, based on a preventive agroclimatic analysis of the area to identify night cooling dynamics (for several meteorological conditions) in the spring. A network of 10 thermohygrometric stations was installed in the area integrating the information obtained by a local agrometeorological station network. The final product was a forecasting bulletin emitted every three hours beginning from the 13:00 p.m. A validation of the system was performed for 2006 to verify the forecast skill.

Simone Orlandini; Marco Mancini; Daniele Grifoni; Gianni Messeri; Anna Dalla Marta; Gaetano Zipoli

116

Development and application of a forecasting system to avoid spring frost damage in chiana valley  

Directory of Open Access Journals (Sweden)

Full Text Available Late frost is one of the more serious adversity for Italian agriculture. Several methods have been developed to protect cultivations, but their application results particularly effective (also from an economic point of view) only if supported by forecasting systems during the more susceptible period of the year. On these basis a forecasting system of late frost in Val di Chiana (an area in central Italy mainly cultivated with cereals and high quality fruits) was developed. The system consists in an empirical model, based on a preventive agroclimatic analysis of the area to identify night cooling dynamics (for several meteorological conditions) in the spring. A network of 10 thermohygrometric stations was installed in the area integrating the information obtained by a local agrometeorological station network. The final product was a forecasting bulletin emitted every three hours beginning from the 13:00 p.m. A validation of the system was performed for 2006 to verify the forecast skill.

Simone Orlandini; Marco Mancini; Daniele Grifoni; Gianni Messeri; Anna Dalla Marta; Gaetano Zipoli

2011-01-01

117

Development and application of a forecasting system to avoid spring frost damage in chiana valley  

Directory of Open Access Journals (Sweden)

Full Text Available Late frost is one of the more serious adversity for Italian agriculture. Several methods have been developed to protect cultivations, but their application results particularly effective (also from an economic point of view) only if supported by forecasting systems during the more susceptible period of the year. On these basis a forecasting system of late frost in Val di Chiana (an area in central Italy mainly cultivated with cereals and high quality fruits) was developed. The system consists in an empirical model, based on a preventive agroclimatic analysis of the area to identify night cooling dynamics (for several meteorological conditions) in the spring. A network of 10 thermohygrometric stations was installed in the area integrating the information obtained by a local agrometeorological station network. The final product was a forecasting bulletin emitted every three hours beginning from the 13:00 p.m. A validation of the system was performed for 2006 to verify the forecast skill.

Simone Orlandini; Marco Mancini; Daniele Grifoni; Gianni Messeri; Anna Dalla Marta; Gaetano Zipoli

2008-01-01

118

Frost heave in helium and other substances  

International Nuclear Information System (INIS)

A thermomolecular pressure associated with a thermal gradient produces the phenomenon known as 'frost heave' in moisture-containing frozen ground. Thermomolecular pressures can occur in any material. As described here it is known that frost heave or thermomolecular pressures can be exhibited by any material undergoing 'premelting,' where liquid exists at temperatures below the normal solid-liquid phase boundary. Yet, the recent work on 4He [Hiroi, et a., Phys. Rev.B 40, 6581 (1989)] is the first published study of thermomolecular pressure in nonaqueous material. The striking prominence of the effect presents advantages of further applications of thermomolecular pressure for fundamental research. This paper describes the phenomenon, outlines the theory and discusses some possible static and dynamic studies of quantum liquids

1992-01-01

119

An improved model for predicting performance of finned tube heat exchanger under frosting condition, with frost thickness variation along fin  

Energy Technology Data Exchange (ETDEWEB)

Frost accumulation on a heat exchanger, a direct result of combined heat and mass transfer between the moist air flowing across a cold surface, causes heat transfer performance degradation due to the insulating effect of frost layer and the coil blockage as the frost grows. The complex geometry of finned tube heat exchangers leads to uneven wall and air temperature distribution inside the coil, and causes variations of frost growth rate and densification along the coil. In this study, a general distributed model with frost formation was developed. The equations for finned tube heat exchanger were derived in non-steady-state manner and quasi-steady state in the frost model. In order to make the model more realistic, the variation of frost along fin due to uneven temperature distribution was included. The presented model is able to predict the dynamic behavior of an air cooler both under non-frost and frost condition. Comparisons were made based on the frost mass accumulation, pressure drop across coil and energy transfer coefficient, and results were found to agree well with reported experimental results. (author)

Tso, C.P. [Multimedia University, Jalan Ayer Keroh Lama, Melaka (Malaysia). Faculty of Engineering and Technology; Cheng, Y.C.; Lai, A.C.K. [Nanyang Technological University, Singapore (Singapore). School of Mechanical and Aerospace Engineering

2006-01-15

120

Frost formation under different gaseous atmospheres  

International Nuclear Information System (INIS)

Rates of water frost growth in a vessel with a cooled horizontal plate were experimentally determined under reduced pressure atmospheres of hydrogen, helium, methane and nitrogen. The mass deposited on the cooled surface under each of the atmospheres was almost in proportion to time. The Sherwood number under the condition of no mist formation, Sh0, in the atmospheres of methane and nitrogen was in good agreement with Catton's equation for natural convection between horizontal parallel plates. Sh0 in a hydrogen atmosphere was unity, which corresponds to control by molecular diffusion in the stagnant gas. The tendency of the decrease in Sh due to mist formation could be evaluated well by multiplying Sh0 by a factor ?CSM. The ?CSM value was calculated based on the critical supersaturation model as a function of the two interface temperatures and the total pressure. Frost growth rates under each atmosphere were in proportion to [(TS1-TW1)t/(1+1/AS1)]0.5. The proportional constant for hydrogen was greater than that for any other tested gas. Agreement and disagreement of the frost effective thermal conductivity with previous models were discussed. (author)

1995-01-01

 
 
 
 
121

METHOD OF PREVENTING FROST DAMAGE OF VEGETATION  

UK PubMed Central (United Kingdom)

A method of maintaining vegetation above frost damage levels in which the roots, stems, trunks or foliage of the vegetation is surrounded by a phase change material having a melting point in excess of the frost damage level, which phase change material is encased in a plurality of bags (10) or in an elongated tubular member. In the case of use of an elongated tubular member, it may be coiled directly about the vegetation or coiled in stacks (22) positioned above the vegetation or laid below ground in rows coiled within the interior of an automotive tire (24) proximate the vegetation which serves to directly collect solar energy. A fluid path is provided through the center of the tubular member which is coupled to a solar collector (34). The solar thermal energy collected thereby is transferred via fluid recirculating in this path to the phase change material such that the phase change material melts. When the ambient temperature falls below frost damage levels, the phase change material, upon cooling and solidifying, releases thermal energy to heat the vegetation. Alternatively, when sufficient solar energy is not available, the transfer fluid is heated by a fuel-fired furnace (36). In the case of use of encasement of the phase change material in a plurality of bags, these fill the torroidal interior of an automotive tire proximate the vegetation which directly collects solar thermal energy which is conducted to the encased phase change material.

WASSERMAN Kurt J.

122

Method of preventing frost damage of vegetation  

UK PubMed Central (United Kingdom)

A method of maintaining vegetation above frost damage levels in which the roots, stems, trunks or foliage of the vegetation is surrounded by a phase change material having a melting point in excess of the frost damage level, which phase change material is encased in a plurality of bags or in an elongated tubular member. In the case of use of an elongated tubular member, it may be coiled directly about the vegetation or coiled in stacks positioned above the vegetation or laid below ground in rows or coiled within the interior of an automotive tire proximate the vegetation which serves to directly collect solar energy. A fluid path is provided through the center of the tubular member which is coupled to a solar collector. The solar thermal energy collected thereby is transfered via fluid recirculating in this path to the phase change material such that the phase change material melts. When the ambient temperature falls below frost damage levels, the phase change material, upon cooling and solidifying, releases thermal energy to heat the vegetation. Alternatively, when sufficient solar energy is not available, the transfer fluid is heated by a fuel-fired furnace. In the case of use of encasement of the phase change material in a plurality of bags, these fill the toroidal interior of an automotive tire proximate the vegetation which directly collects solar thermal energy which is conducted to the encased phase change material.

WASSERMAN KURT J

123

Frost formation on a plate with different surface hydrophilicity  

Energy Technology Data Exchange (ETDEWEB)

The objectives of this study are to develop frost maps for two different surfaces having two different hydrophilic characteristics and to find ambient conditions associated with the formation of frost structures. Test samples with two different surfaces having dynamic contact angle (DCA) of 23{sup o} and 88{sup o} were installed in a wind tunnel and exposed to a humid airflow. Frost structure is observed with a visualization system in the operating conditions of household refrigerator: airflow temperature in the range of 20 {sup o}C, humidity in the range of 2.64-9.36 g/kg, Reynolds number in the range of 7000-17,000 and cold plate temperature in the range of -11.6 to -28.4 {sup o}C. As a result of this study, frost structures are classified and frost maps are proposed for two different surface hydrophilicities. Surface with low DCA (23{sup o}) shows lower frost thickness and higher frost density than that with high DCA (88{sup o}). It was found that frost structures on surfaces with different DCA are similar. However, low DCA surface at low humidity provides 20-30% denser frost formation due to the shift of areas with different structures. (Author)

Hyunuk Lee; Jongmin Shin; Samchul Ha; Bongjun Choi [Digital Appliance Co. Research Lab., L G Electronics Inc., Changwon, Kyoungnam (Korea); Jaekeun Lee

2004-10-01

124

Frost growth and melting characteristics on glass fibers  

Energy Technology Data Exchange (ETDEWEB)

Frost growth over glass fibers of uniform diameter is observed using a microscope to investigate the cyclic effect of frosting and melting on the moisture accumulation in fiber-glass insulation, typically encountered in cold climate applications. A simple-three-dimensional conduction model is presented to demonstrate the temperature and local heat flux variation in the accumulated frost/water and attaching fibers. The numerical results show that the subcooling period for frost growth on fibers strongly depends on the fiber sizes and weakly depends on droplet sizes. For fiber diameters of greater than 0.23 mm, the local thermal equilibrium is no longer a good assumption.

Tao, Y.X. [Tennessee State Univ., Nashville, TN (United States). Dept. of Mechanical Engineering; Mao, Y.; Besant, R.W. [Univ. of Saskatchewan, Saskatoon, Saskatchewan (Canada). Dept. of Mechanical Engineering

1995-12-31

125

Simple manhole innovation cuts frost heave in pavement  

Energy Technology Data Exchange (ETDEWEB)

A method to prevent pavement from heaving and cracking around manholes has been developed by the National Research Council's Institute for Research in Construction (IRC). The simple method harnesses and uses the natural warmth of the water flowing through the storm and sanitary sewers to protect the soil around the manhole from frost. The heat from the sewers is harnessed by changing the design of the manhole by plugging the holes and adding a layer of insulation under the cover. The soil surrounding the manhole is also altered by placing large crushed stones around the manhole to help dissipate heat in all directions around the manhole. IRC has successfully carried out field tests with engineers in Ottawa. Their test manholes remained flat and free of cracks even after a winter of fluctuating temperatures and de-icing salt. The cost for the entire installation procedure is just slightly more than conventional manhole construction, but considering that the life of the pavement can be extended, municipalities can retrieve their investment. Secondary benefits include environmental benefits derived by less traffic disruption, less damage to vehicles, less material and fewer emissions. 3 figs.

Svec, O.J.

2000-03-31

126

Soybean susceptibility to manufactured nanomaterials with evidence for food quality and soil fertility interruption.  

UK PubMed Central (United Kingdom)

Based on previously published hydroponic plant, planktonic bacterial, and soil microbial community research, manufactured nanomaterial (MNM) environmental buildup could profoundly alter soil-based food crop quality and yield. However, thus far, no single study has at once examined the full implications, as no studies have involved growing plants to full maturity in MNM-contaminated field soil. We have done so for soybean, a major global commodity crop, using farm soil amended with two high-production metal oxide MNMs (nano-CeO(2) and -ZnO). The results provide a clear, but unfortunate, view of what could arise over the long term: (i) for nano-ZnO, component metal was taken up and distributed throughout edible plant tissues; (ii) for nano-CeO(2), plant growth and yield diminished, but also (iii) nitrogen fixation--a major ecosystem service of leguminous crops--was shut down at high nano-CeO(2) concentration. Juxtaposed against widespread land application of wastewater treatment biosolids to food crops, these findings forewarn of agriculturally associated human and environmental risks from the accelerating use of MNMs.

Priester JH; Ge Y; Mielke RE; Horst AM; Moritz SC; Espinosa K; Gelb J; Walker SL; Nisbet RM; An YJ; Schimel JP; Palmer RG; Hernandez-Viezcas JA; Zhao L; Gardea-Torresdey JL; Holden PA

2012-09-01

127

Soybean susceptibility to manufactured nanomaterials with evidence for food quality and soil fertility interruption.  

Science.gov (United States)

Based on previously published hydroponic plant, planktonic bacterial, and soil microbial community research, manufactured nanomaterial (MNM) environmental buildup could profoundly alter soil-based food crop quality and yield. However, thus far, no single study has at once examined the full implications, as no studies have involved growing plants to full maturity in MNM-contaminated field soil. We have done so for soybean, a major global commodity crop, using farm soil amended with two high-production metal oxide MNMs (nano-CeO(2) and -ZnO). The results provide a clear, but unfortunate, view of what could arise over the long term: (i) for nano-ZnO, component metal was taken up and distributed throughout edible plant tissues; (ii) for nano-CeO(2), plant growth and yield diminished, but also (iii) nitrogen fixation--a major ecosystem service of leguminous crops--was shut down at high nano-CeO(2) concentration. Juxtaposed against widespread land application of wastewater treatment biosolids to food crops, these findings forewarn of agriculturally associated human and environmental risks from the accelerating use of MNMs. PMID:22908279

Priester, John H; Ge, Yuan; Mielke, Randall E; Horst, Allison M; Moritz, Shelly Cole; Espinosa, Katherine; Gelb, Jeff; Walker, Sharon L; Nisbet, Roger M; An, Youn-Joo; Schimel, Joshua P; Palmer, Reid G; Hernandez-Viezcas, Jose A; Zhao, Lijuan; Gardea-Torresdey, Jorge L; Holden, Patricia A

2012-08-20

128

Neural Network-Based Model for Landslide Susceptibility and Soil Longitudinal Profile Analyses : two case studies  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The purpose of this study was to create an empirical model for assessing the landslide risk potential at Savadkouh Azad University, which is located in the rural surroundings of Savadkouh, about 5 km from the city of Pol-Sefid in northern Iran. The soil longitudinal profile of the city of Babol, loc...

Farrokhzad, F.; Barari, Amin; Choobbasti, A. J.; Ibsen, Lars Bo

129

Analysis and Simulation of Frost's Beamformer  

Directory of Open Access Journals (Sweden)

Full Text Available Sensor arrays are often used for a signal separation from noisesusing the information about the direction of arrival. The aim of thispaper is to analyze Frost's beamformer with respect to the speechpreprocessing for the hearing impaired people. The frequency responseof the system including the background noise attenuation are derived asfunctions of the direction of arrival. The derivation supposes auniform linear array of sensors and plane waves. It is shown that thenumber of possible configurations can be decreased by using somesymmetries. The impact of the used algorithm constraint on thefrequency response and subsequently on the directional noisesuppression is derived analytically.

M. Strupl; P. Sovka

2003-01-01

130

Internal frost damage in concrete - experimental studies of destruction mechanisms  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The aim of the study was to identify mechanisms acting at internal frost destruction of concrete. By 'internal frost destruction' is meant damage caused inside concrete that is moisture insulated from the surroundings, i.e. when no moisture exchange with the surroundings is possible during freeze-th...

Fridh, Katja

131

Heavy metal contents and magnetic susceptibility of soils along an urban-rural gradient in rapidly growing city of Eastern China.  

UK PubMed Central (United Kingdom)

The accumulation of heavy metals (Cd, Cr, Cu, Pb and Zn) and magnetic minerals in soils along an urban-rural gradient in the rapidly growing Hangzhou City, Eastern China, was measured. The analytical results indicated that heavy metal concentrations, magnetic susceptibility (chilf) and saturation isothermal remnant magnetization (SIRM) in soils decreased with increasing distance from the urban center. The significant relationships existed between heavy metal concentrations, chilf and SIRM and distance from the urban center. The soils in the urban areas were enriched with Cd, Cu, Pb and Zn. Elevated concentrations of heavy metals (especially Cd and Zn) in urban areas indicated the evidence for the accumulation of heavy metal contaminants from anthropogenic activities. Enhanced heavy metal concentrations and magnetic susceptibility were located in the uppermost soil horizons (0-10 cm), decreasing downwards to background values. The significant positive correlations between the Tomlinson Pollution Load Index (PLI) and magnetic susceptibility and SIRM were observed in polluted soil samples. Strong positive correlation indicated that magnetic screening/monitoring provided a fast and non-destructive tool, which can be effectively used as a proxy to detect environmental pollution in rapidly growing urbanization regions affected by anthropogenic activities.

Lu S; Wang H; Bai S

2009-08-01

132

Moisture and frost in fiberglass insulation  

Energy Technology Data Exchange (ETDEWEB)

An experimental study was conducted to measure the heat of adsorption of water vapor in fiberglass insulation materials of the type typically used in Canadian houses. Measurements were made over a range of temperature and humidity conditions while being accurately monitored in the laboratory. Using the measured data, a time-dependent 1-dimensional theoretical/numerical heat/mass transfer model was developed that combines adsorption/desorption, condensation/evaporation, and ablimation/sublimation with water vapor diffusion in fiberglass insulation. The accuracy of the model was verified using an existing cold-temperature laboratory test facility involving the same physical phenomena considered in the model. The effects of hygroscopicity, condensation, and frosting on the thermal performance of fiberglass insulation was examined. For initially dry glass fiber insulation of medium density, the effects of hygroscopicity on the temperature field and heat loss were found to be negligible if the sample is isolated from the ambient mass transfer. However, these effects are very significant when one side of the insulation is open to moist air during a transport process. Frost accumulation results in an increase in the heat flux ratio as compared to the process when only condensation takes place, if the ambient relative humidity is approximately above 0.40. 19 refs., 14 figs., 2 tabs.

Besant, R.W.; Tao Yongxin.

1992-04-01

133

Mathematical modeling of heat transfer between the plant seedling and the environment during a radiation frost  

Directory of Open Access Journals (Sweden)

Full Text Available The power of the internal heat source sufficient to maintain a positive temperature of plants during one of the possible form of cold stress - radiation frost was determined with the help of numerical simulation.The simulation of unsteady heat transfer in the soil-plant-air system in the conditions of radiation frost showed that the the ground part of plants is cooling most rapidly, and this process is partially slowed down by the natural-convection heat transfer with warmer air. If the frost is not continuous, the radiative cooling is the main danger for plant. The necessary power of heat-production inside plant that allows it to avoid hypothermia depends both on natural conditions and the size of the plant. For plants with a typical diameter of the stem about 2 mm this heat-production should be from 50 to 100 W / kg. Within 2 hours a total amount of heat about 0.5 MJ / kg in the plant should be allocated. Larger plants will have a smaller surface to mass ratio, and the maintaining of it's temperature will require a lower cost of nutrients per unit, accordingly. Modeling of the influence of plant surface trichomes presence on the process of its cooling showed that the role of trichomes in the protection of plants from hypothermia during radiation frost usually is negative due to the fact that the presence of trichomes increases the radiative heat transfer from the plant and the impediment in air movement near the plant reduces heat flux entering the plant from a warmer air. But in cases where the intensity of heat generation within the plant is sufficient for the maintenance of the plant temperature higher than the air temperature, the presence of trichomes impairs heat transfer from plant to air, and therefore contributes to a better heating of plants.

Finnikov K.A.; A.V. Minakov; A.A. Dekterev; A.A. Gavrilov; A.M. Korzun; V.K. Voinikov; A.V. Kolesnichenko

2010-01-01

134

Delayed frost growth on jumping-drop superhydrophobic surfaces.  

UK PubMed Central (United Kingdom)

Self-propelled jumping drops are continuously removed from a condensing superhydrophobic surface to enable a micrometric steady-state drop size. Here, we report that subcooled condensate on a chilled superhydrophobic surface are able to repeatedly jump off the surface before heterogeneous ice nucleation occurs. Frost still forms on the superhydrophobic surface due to ice nucleation at neighboring edge defects, which eventually spreads over the entire surface via an interdrop frost wave. The growth of this interdrop frost front is shown to be up to 3 times slower on the superhydrophobic surface compared to a control hydrophobic surface, due to the jumping-drop effect dynamically minimizing the average drop size and surface coverage of the condensate. A simple scaling model is developed to relate the success and speed of interdrop ice bridging to the drop size distribution. While other reports of condensation frosting on superhydrophobic surfaces have focused exclusively on liquid-solid ice nucleation for isolated drops, these findings reveal that the growth of frost is an interdrop phenomenon that is strongly coupled to the wettability and drop size distribution of the surface. A jumping-drop superhydrophobic condenser minimized frost formation relative to a conventional dropwise condenser in two respects: preventing heterogeneous ice nucleation by continuously removing subcooled condensate, and delaying frost growth by limiting the success of interdrop ice bridge formation.

Boreyko JB; Collier CP

2013-02-01

135

Delayed frost growth on jumping-drop superhydrophobic surfaces.  

Science.gov (United States)

Self-propelled jumping drops are continuously removed from a condensing superhydrophobic surface to enable a micrometric steady-state drop size. Here, we report that subcooled condensate on a chilled superhydrophobic surface are able to repeatedly jump off the surface before heterogeneous ice nucleation occurs. Frost still forms on the superhydrophobic surface due to ice nucleation at neighboring edge defects, which eventually spreads over the entire surface via an interdrop frost wave. The growth of this interdrop frost front is shown to be up to 3 times slower on the superhydrophobic surface compared to a control hydrophobic surface, due to the jumping-drop effect dynamically minimizing the average drop size and surface coverage of the condensate. A simple scaling model is developed to relate the success and speed of interdrop ice bridging to the drop size distribution. While other reports of condensation frosting on superhydrophobic surfaces have focused exclusively on liquid-solid ice nucleation for isolated drops, these findings reveal that the growth of frost is an interdrop phenomenon that is strongly coupled to the wettability and drop size distribution of the surface. A jumping-drop superhydrophobic condenser minimized frost formation relative to a conventional dropwise condenser in two respects: preventing heterogeneous ice nucleation by continuously removing subcooled condensate, and delaying frost growth by limiting the success of interdrop ice bridge formation. PMID:23286736

Boreyko, Jonathan B; Collier, C Patrick

2013-01-08

136

Nutritional Status and Susceptibility of Advanced Chickpea Germplasm to Low Soil Zinc and Boron  

Directory of Open Access Journals (Sweden)

Full Text Available Shoot samples at preflowering stage and grains at maturity from four replicated field trials on advanced germplasm of chickpea along with some of the commercial varieties were collected. Three trials consisted of Desi germplasm with 12, 12, and 8 entries while the fourth one had 11 entries of Kabuli material. The advanced lines appeared to be highly promising as they gave maximum increase over the old check varieties in grain yield upto 60 percent in first trial followed by 58 percent in second, 53 percent in third and 43 percent in the 4th one. On the overall basis, the whole germplasm under study contained sufficient B and Cu, while Zn and P (in grain) were marginal if not deficient. Almost all the material had relatively higher B in the grain than that of cereals like wheat. After field survey, a followup soil pot culture study was conducted employing 5 varieties and 2 lines on a soil with marginal Zn and B. Variety 6153 responded to 5 mg kg -1 Zn application by 39, CM 72 by 26, NIFA 95 by 17 and mutant CM 1571-1-A by 11 percent, while remaining responded negligibly. Mutant CM 31-1 responded to 1 mg kg -1 B application by 30, CM 1571-1-A, C 44 and 6153 shared the response by 27 percent. Remaining three did not respond or responded negatively. All the entries in the four trials contained marginal Zn i.e.,-1 and sufficient B i.e., >30 mg kg-1, yet some of them responded to the applications markedly indicating their high B and Zn requirement than reported in the literature.

M.A.Kausar; M.Sadiq; M.A.Khan; M. Hassan; M.A. Haq

2000-01-01

137

Effect of variations in air speed on cross-flow cylinder frosting  

International Nuclear Information System (INIS)

[en] In this paper the effect of fluctuating air speed on frost growth and heat transfer to a cylinder in cross-flow is discussed. Frost-growth of up to 20 hours is simulated using an experimentally validated finite difference computer model. Graphical results are presented for frost mass, frost depth, frost surface temperature and heat transfer versus time under both steady and fluctuating air speed conditions. In general, it is found that a thinner, more dense frost layer develops under fluctuating air speed conditions giving improved heat transfer. This phenomenon may be explained by the increased frequency of frost surface thaw/freeze cycles when fluctuating air speed conditions prevail

1990-01-01

138

Frost-protected shallow foundation: work in seasonally-freezing through grounds, practice of thermal calculation (rus)  

Directory of Open Access Journals (Sweden)

Full Text Available The object of research is frost-protected shallow foundations.The article focuses on a technique of solving the nonstationary and nonlinear problem of freezing/thawing of soil in a 2D target setting, using software based on the finite-element method. The COSMOS/M package from Structural Research & Analysis Corp. is used as an example. The article also mentions some peculiarities of data input, caused by the non-linearity and nonstationarity of the problem.

Veselov V.V.; Belyakov V.A.

2011-01-01

139

Nitrogen frost migration on Triton: A historical model  

International Nuclear Information System (INIS)

The author presents the results of numerical simulations of the seasonal migration of nitrogen frost on Triton, constrained by Voyager observations of atmospheric pressure, temperature, and albedo distribution. Most of the exposed nitrogen is probably seasonal frost, whose migration can produce major variations in atmospheric pressure. For instance, models explored here predict a tenfold pressure drop in the coming decade. The observed albedo patterns can be understood if fresh nitrogen frost is relatively dark butt brightens with increasing insolation in a manner analogous to the Martian southern CO2 cap

1990-01-01

140

Characteristics of heat pump system operating with frost formation  

International Nuclear Information System (INIS)

This paper reports on the performance of heat pump system operating with frost formation that was predicted related to the change of the performance of evaporator due to frosting. The predicted results were compared with the experimental results using a cross-finned tube evaporator. The poor performance of evaporator due to frosting causes the decrease in the heating capacity as the results of the drop of the evaporating temperature and the decrease in the flow rate of refrigerant. The calculated results were in agreement with the experimental results

1991-01-01

 
 
 
 
141

Lupus relapse presented as frosted branch retinal angiitis: case report.  

UK PubMed Central (United Kingdom)

PURPOSE: To describe a systemic lupus erythematosus (SLE) relapse, which presented as frosted branch retinal angiitis. DESIGN: Clinical case report. METHODS: A 16-year-old female patient had an SLE relapse that appeared as frosted branch angiitis while being treated with deflazacort and azathioprine. RESULTS: Complete resolution of the vasculitis was achieved with a 3-day course of pulsed intravenous methylprednisolone and oral prednisone 3 weeks later. CONCLUSIONS: Even with proper immunosuppressive treatment, SLE can relapse. This case presented as frosted branch retinal angiitis, which is a clinical picture that is rarely described in SLE.

Hernandez-Da Mota SE; Arellanes-Garcia L; Recillas-Gispert C; Cornejo-Ballesteros H; Melgoza-del-Angel C; Teran-Estrada L; Sanchez-Gonzalez R

2011-10-01

142

Suscetibilidade magnética do solo e estimação da capacidade de suporte à aplicação de vinhaça/ Soil magnetic susceptibility for estimating the support capacity to vinasse application  

Scientific Electronic Library Online (English)

Full Text Available Abstract in portuguese O objetivo deste trabalho foi avaliar a eficiência da suscetibilidade magnética do solo para estimar a capacidade de suporte de áreas à aplicação de vinhaça. Foram coletadas 241 amostras de solo, de uma área de 380 ha, nas quais foram determinados os atributos químicos, os teores de argila e a suscetibilidade magnética do solo. Foram calculadas as doses de vinhaça recomendadas para cada amostra. Os dados foram submetidos à análise estatística descritiva, e f (more) oram desenvolvidos modelos de regressão entre a suscetibilidade magnética e os outros atributos avaliados. A análise da dependência espacial dos dados foi feita com uso da geoestatística. Foram construídos mapas de krigagem e variogramas cruzados, para averiguar a correlação espacial entre a suscetibilidade magnética e os atributos estudados. Com base no mapa de recomendação de vinhaça, nas classes de solo e nos mapas de krigagem, foram calculadas as doses médias de vinhaça e as capacidades de suporte médias, ponderadas pela área. A suscetibilidade magnética apresenta correlação espacial linear significativa com as doses de vinhaça recomendadas e com a capacidade de suporte do solo à aplicação desse efluente, e pode ser utilizada como componente da função de pedotransferência, na quantificação indireta da capacidade de suporte. Abstract in english The objective of this work was to evaluate the magnetic susceptibility efficiency for estimating the support capacity of areas for vinasse application. Two hundred forty-one soil samples were collected from a 380-ha area, on which soil chemical properties, clay content, and magnetic susceptibility were determined. Vinasse requirement was calculated for each sample. Data were subjected to descriptive statistical analysis, and regression models were developed between magnet (more) ic susceptibility and the other evaluated attributes. The analysis of data spatial dependence was performed using geostatistics. Kriging maps and cross variograms were built in order to investigate the spatial correlation between soil magnetic susceptibility and studied attributes. Based on the map of vinasse requirement, on the soil classes, and on the kriging map, calculations were done for average vinasse dose and average soil support capacity, weighted by the area. Magnetic susceptibility has significant linear spatial correlation with recommended vinasse doses and soil support capacity for the application of this effluent, and it can be used as a pedotransfer function for indirect quantification of soil support capacity.

Peluco, Rafael Gonçalves; Marques Júnior, José; Siqueira, Diego Silva; Pereira, Gener Tadeu; Barbosa, Ronny Sobreira; Teixeira, Daniel de Bortoli; Adame, Cássia Rita; Cortez, Lucas Aguilar

2013-06-01

143

Mechanism of frost formation on lubricant-impregnated surfaces.  

Science.gov (United States)

Frost formation is a major problem affecting a variety of industries including transportation, power generation, construction, and agriculture. Currently used active chemical, thermal, and mechanical techniques of ice removal are time-consuming and costly. The use of nanotextured coatings infused with perfluorinated oil has recently been proposed as a simple passive antifrosting and anti-icing method. However, we demonstrate that the process of freezing subcooled condensate and frost formation on such lubricant-impregnated surfaces is accompanied by the migration of the lubricant from the wetting ridge and from within the textured substrate to the surface of frozen droplets. For practical applications, this mechanism can comprise the self-healing and frost-repelling characteristics of lubricant impregnated-surfaces, regardless of the underlying substrate's topography. Thus, further research is necessary to develop liquid-texture pairs that will provide a sustainable frost suppression method. PMID:23565857

Rykaczewski, Konrad; Anand, Sushant; Subramanyam, Srinivas Bengaluru; Varanasi, Kripa K

2013-04-22

144

Frost-Protected Shallow Foundations. Phase 2. Final Report.  

Science.gov (United States)

Frost-protected shallow foundations (FPSFs) offer a proven technology designed to substantially lower construction costs in colder climates, enhancing housing affordability for families in many parts of the United States. This document provides step-by-st...

J. H. Crandell E. M. Lund M. G. Bruen M. S. Nowak

1994-01-01

145

Design Guide for Frost-Protected Shallow Foundations.  

Science.gov (United States)

Frost-protected shallow foundations (FPSFs) offer a proven technology designed to substantially lower construction costs in colder climates, enhancing housing affordability for families in many parts of the United States. This document provides step-by-st...

1994-01-01

146

Mechanism of frost formation on lubricant-impregnated surfaces.  

UK PubMed Central (United Kingdom)

Frost formation is a major problem affecting a variety of industries including transportation, power generation, construction, and agriculture. Currently used active chemical, thermal, and mechanical techniques of ice removal are time-consuming and costly. The use of nanotextured coatings infused with perfluorinated oil has recently been proposed as a simple passive antifrosting and anti-icing method. However, we demonstrate that the process of freezing subcooled condensate and frost formation on such lubricant-impregnated surfaces is accompanied by the migration of the lubricant from the wetting ridge and from within the textured substrate to the surface of frozen droplets. For practical applications, this mechanism can comprise the self-healing and frost-repelling characteristics of lubricant impregnated-surfaces, regardless of the underlying substrate's topography. Thus, further research is necessary to develop liquid-texture pairs that will provide a sustainable frost suppression method.

Rykaczewski K; Anand S; Subramanyam SB; Varanasi KK

2013-04-01

147

Forecast of frost days based on monthly temperatures  

Energy Technology Data Exchange (ETDEWEB)

Abstract Although frost can cause considerable crop damage, and practices have been developed to mitigate forecasted frost, frost forecasting technologies have not changed for years. This paper reports on a new method based on successive application of two models to forecast the number of monthly frost days for several Community of Madrid (Spain) meteorological stations. The first is an autoregressive integrated moving average (ARIMA) stochastic model that forecasts minimum monthly absolute temperature (t{sub m}in) and average monthly minimum temperature ({mu}{sub t}) following Box and Jenkins methodology. The second model relates monthly temperatures (t{sub m}in, {mu}{sub t}) to the minimum daily temperature distribution during one month. Three ARIMA models were identified. They present the same seasonal behaviour (integrated moving average model) and different non-seasonal part: autoregressive model (Model 1), integrated moving average model (Model 2) and autoregressive and moving average model (Model 3). The results indicate that minimum daily temperature (t{sub d}min) for the meteorological stations studied followed a normal distribution each month with a very similar standard deviation through out the years. This standard deviation obtained for each station and each month could be used as a risk index for cold months. The application of Model 1 to predict minimum monthly temperatures produced the best frost days forecast. This procedure provides a tool for crop managers and crop insurance companies to assess the risk of frost frequency and intensity, so that they can take steps to mitigate frost damage and estimate the damage that frost would cause. (Author) 41 refs.

Castellanos, M. T.; Tarquis, A. M.; Corato, M. C.; Saa, A.

2009-07-01

148

Building energy efficiency and its effect on the frost insulation  

Energy Technology Data Exchange (ETDEWEB)

The energy efficiency of new buildings has improved significantly and is still improving. As the thermal insulation of the building envelope increases other properties and 'thumb' values might also change. Especially when the thermal transmittance (U-value) of the slab on the ground decreases, the frost insulation should also be reconsidered. The aim of this study is to find out how the frost insulation changes when the base floor and foundation insulation change. (orig.)

Airaksinen, M., Email: miimu.airaksinen@vtt.fi

2012-06-15

149

Frost-related dieback of Swedish and Estonian Salix plantations due to pathogenic and ice nucleation-active bacteria  

Energy Technology Data Exchange (ETDEWEB)

During the past decade, important dieback has been observed in short-rotation forestry plantations of Salix viminalis and S. dasyclados in Sweden and Estonia, plantations from which the isolation of ice nucleation-active (INA) and pathogenic bacteria has also been reported. This thesis investigates the connection between bacterial infection and frost as a possible cause for such damage, and the role played by internal and external factors (e.g. plant frost sensitivity, fertilisation) in the dieback observed. Bacterial floras isolated from ten Salix clones growing on fertilised/unfertilised mineral soil or nitrogen-rich organic soil, were studied. Culturable bacterial communities present both in internal necrotic tissues and on the plant surface (i.e. epiphytes) were isolated on two occasions (spring and autumn). The strains were biochemically characterised (with gram, oxidase and fluorescence tests), and tested for ice nucleation-activity. Their pathogenic properties were studied with and without association to a freezing stress. Certain strains were eventually identified with BIOLOG plates and 16S rRNA analysis. A high number of culturable bacterial strains was found in the plant samplings, belonging mainly to Erwinia and Sphingomonas spp.; pathogenic and INA communities being mostly Erwinia-, Sphingomonas- and Xanthomonas-like. The generally higher plant dieback noted in the field on nutrient-rich soils and for frost sensitive clones was found connected to higher numbers of pathogenic and INA bacteria in the plants. We thus confirm Salix dieback to be related to a synergistic effect of frost and bacterial infection, possibly aggravated by fertilisation.

Cambours, M.A.

2004-07-01

150

?Determination of Frost Free Season by Using Dates of First and Last Advection and Radiation Frosts in Zanjan, Gazvin and Tehran Regions  

Directory of Open Access Journals (Sweden)

Full Text Available Dates of start and end of frost based on minimum shelter temperature equal to or less than 0°C were studied in Zanjan, Ghazvin and Tehran during 1961-2000. The cause of these frosts was determined by weather parameter values at observation hours and the aid of synoptic maps. Frost series based upon last spring or first fall advection are defined and found to be random and normally distributed. The "potential growing season", defined as the interval between spring last and first fall advection frosts, is found to be 29 days in Zanjan, 23 days in Ghazvin and 10 days in Tehran longer than the "growing season" defined by the interval from last spring to first fall occurrences of minimum shelter temperature of 0°C or less. The numbers of radiation frosts in the interval between first radiation frosts in fall or last radiation frost in spring and related advection frost were counted and found that this parameter is greater in Zanjan. Frostless days between the first two fall frosts and last two spring frosts show that the lengthening of spring season with one night protection is possible for 4 days in Zanjan, 6 in Gazvin and 4 in Tehran, providing that first fall and spring last frost is radiation. Results of this study permit estimating the practicality of frost protection for specialized crops in the area of study.

K Noohi; F Sahraeian; M Pedram; A Sedaghat Kerdar

2009-01-01

151

Delayed Frost Growth on Jumping-Drop Superhydrophobic Surfaces  

Energy Technology Data Exchange (ETDEWEB)

Self-propelled jumping drops are continuously removed from a condensing superhydrophobic surface to enable a micrometric steady-state drop size. Here, we report that subcooled condensate on a chilled superhydrophobic surface are able to repeatedly jump off the surface before heterogeneous ice nucleation occurs. Frost still forms on the superhydrophobic surface due to ice nucleation at neighboring edge defects, which eventually spreads over the entire surface via an inter-drop frost wave. The growth of this inter-drop frost front is shown to be up to three times slower on the superhydrophobic surface compared to a control hydrophobic surface, due to the jumping-drop effect dynamically minimizing the average drop size and surface coverage of the condensate. A simple scaling model is developed to relate the success and speed of inter-drop ice bridging to the drop size distribution. While other reports of condensation frosting on superhydrophobic surfaces have focused exclusively on liquid-solid ice nucleation for isolated drops, these findings reveal that the growth of frost is an inter-drop phenomenon that is strongly coupled to the wettability and drop size distribution of the surface. A jumping-drop superhydrophobic condenser was found to be superior to a conventional dropwise condenser in two respects: preventing heterogeneous ice nucleation by continuously removing subcooled condensate, and delaying frost growth by minimizing the success of interdrop ice bridge formation.

Boreyko, Jonathan B [ORNL; Collier, Pat [ORNL

2013-01-01

152

Frost risk for overwintering crops in a changing climate  

Science.gov (United States)

Climate change scenarios predict a general increase in daily temperatures and a decline in snow cover duration. On the one hand, higher temperature in fall and spring may facilitate the development of overwintering crops and allow the expansion of winter cropping in locations where the growing season is currently too short. On the other hand, higher temperatures prior to winter crop dormancy slow down frost hardening, enhancing crop vulnerability to temperature fluctuation. Such vulnerability may be exacerbated by reduced snow cover, with potential further negative impacts on yields in extremely low temperatures. We propose a parsimonious probabilistic model to quantify the winter frost damage risk for overwintering crops, based on a coupled model of air temperature, snow cover, and crop minimum tolerable temperature. The latter is determined by crop features, previous history of temperature, and snow cover. The temperature-snow cover model is tested against meteorological data collected over 50 years in Sweden and applied to winter wheat varieties differing in their ability to acquire frost resistance. Hence, exploiting experimental results assessing crop frost damage under limited temperature and snow cover realizations, this probabilistic framework allows the quantification of frost risk for different crop varieties, including in full temperature and precipitation unpredictability. Climate change scenarios are explored to quantify the effects of changes in temperature mean and variance and precipitation regime over crops differing in winter frost resistance and response to temperature.

Vico, Giulia; Weih, Martin

2013-04-01

153

Frost rings in trees as records of major volcanic eruptions  

Energy Technology Data Exchange (ETDEWEB)

The occurrence of frost-damage zones in accurately dated tree-ring sequences from subalpine bristlecone pines in the western U.S. is closely linked to climatological effects of major volcanogenic atmospheric veils. One important consequence of a large explosive eruption is the spread of a stratospheric veil of fine silicate ash and sulfur aerosols, with resultant surface cooling that may be accentuated at high latitudes by the veil's long residence time in the stratosphere. Data from pines at seven localities were studied. Frost rings vary from one event to another in the severity of cell damage, in their frequency of occurrence at a particular site, and in their range of distribution. The results are based on homogeneous samples of old, well-established trees. These frost rings represent new, independent proxy records of climatically effective eruptions during the past several thousand years. However, frost events that are unrelated to aerosol veils have occurred; and, there have been notable eruptions with no associated frost ring. These preliminary findings suggest the need for empirical studies of regional climatic variability and analysis of modelling results to see how important volcanogenic aerosol veils may be as a casual factor in frost-ring formation. 40 references, 2 figures, 3 tables.

LaMarche, V.C. Jr.; Hirschboeck, K.K.

1984-01-12

154

Soil macroaggregate dynamics in a mountain spatial climate gradient  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We investigated the response of soil macroaggregate dynamics to soil temperature modification along a spatial gradient located on a forested north-facing slope in the southern French Alps, simulating long-term adjustment of soil-plant interactions to absence or occurrence of soil frost. Soil macroag...

Cécillon, Lauric; De Mello, Nilvania A.; De Danieli, Sébastien; Brun, Jean-Jacques

155

Combined effects of copper, desiccation, and frost on the viability of earthworm cocoons  

Energy Technology Data Exchange (ETDEWEB)

The effects of heavy metal pollution on earthworms have been extensively studied, but no studies have examined how earthworms react if they are simultaneously exposed to metal pollution and climatic stress. This question has been addressed in a laboratory study where cocoons of Aporrectodea caliginosa and Dendrobaena octaedra were initially exposed to copper in aqueous solutions of copper chloride and thereafter exposed to realistic degrees of either desiccation or frost. Earthworm embryos absorbed copper in amounts comparable to concentrations found in various tissues of earthworms from metal-polluted soils. Desiccation and copper exposure in combination had synergistic effects on survival rates for both species. For example, at full saturation, the NOEC (the highest tested concentration with no statistically significant effect) for copper of A. caliginosa was 12 mg/L, whereas at 97% relative humidity it was only 6 mg/L. Frost and copper exposure in combination also showed synergistic effects in some experiments. No cocoons of A. caliginosa exposed to 20 mg copper/L were viable after exposure to {minus}3 C but at 0 C viability was as high as 95%. The same tendency was seen in D. octaedra but not as clearly as in A/. caliginosa. A change of the environmental conditions (moisture, temperature) to increasing severity caused a shift in the statistically derived NOEC toward lower critical values of copper. The involvement of combination effects in ecotoxicological tests could therefore improve risk assessment of soil-polluting compounds.

Holmstrup, M. [National Environmental Research Inst., Silkeborg (Denmark). Dept. of Terrestrial Ecology; Petersen, B.F. [National Environmental Research Inst., Silkeborg (Denmark). Dept. of Terrestrial Ecology]|[Univ. of Aarhus (Denmark); Larsen, M.M. [National Environmental Research Inst., Roskilde (Denmark). Dept. of Marine Ecology and Microbiology

1998-01-01

156

Experimental measurements of the effects of frost formation on heat exchanger performance  

International Nuclear Information System (INIS)

Frost formation on compact heat exchangers can lead to reductions in heat transfer of the order of 50 to 75% and to substantial increases in pressure drop. These effects are dependent upon the spatial pattern of the frost deposition, the growth history of the frost, and the thicknesses of the frost. This paper describes a series of experiments to measure the effects of frost when cold air (260 - 273 K) is passing through the exchanger. It is found that the thermal performance is a function of time and specific humidity levels while the pressure is function only of the frost thickness and surface roughness

1990-01-01

157

Forecast of Frost Days Based on Monthly Temperatures  

Science.gov (United States)

Although frost can cause considerable crop damage and mitigation practices against forecasted frost exist, frost forecasting technologies have not changed for many years. The paper reports a new method to forecast the monthly number of frost days (FD) for several meteorological stations at Community of Madrid (Spain) based on successive application of two models. The first one is a stochastic model, autoregressive integrated moving average (ARIMA), that forecasts monthly minimum absolute temperature (tmin) and monthly average of minimum temperature (tminav) following Box-Jenkins methodology. The second model relates these monthly temperatures to minimum daily temperature distribution during one month. Three ARIMA models were identified for the time series analyzed with a stational period correspondent to one year. They present the same stational behavior (moving average differenced model) and different non-stational part: autoregressive model (Model 1), moving average differenced model (Model 2) and autoregressive and moving average model (Model 3). At the same time, the results point out that minimum daily temperature (tdmin), for the meteorological stations studied, followed a normal distribution each month with a very similar standard deviation through years. This standard deviation obtained for each station and each month could be used as a risk index for cold months. The application of Model 1 to predict minimum monthly temperatures showed the best FD forecast. This procedure provides a tool for crop managers and crop insurance companies to asses the risk of frost frequency and intensity, so that they can take steps to mitigate against frost damage and estimated the damage that frost would cost. This research was supported by Comunidad de Madrid Research Project 076/92. The cooperation of the Spanish National Meteorological Institute and the Spanish Ministerio de Agricultura, Pesca y Alimentation (MAPA) is gratefully acknowledged.

Castellanos, M. T.; Tarquis, A. M.; Morató, M. C.; Saa-Requejo, A.

2009-04-01

158

Frost Multidimensional Perfectionism Scale: the portuguese version/ Frost Multidimensional Perfectionism Scale: versão portuguesa  

Scientific Electronic Library Online (English)

Full Text Available Abstract in portuguese CONTEXTO: A Escala Multidimensional de Perfeccionismo de Frost (FMPS) é uma das escalas mais usadas em todo o mundo para avaliar o perfeccionismo. OBJETIVO: Analisar as características psicométricas da versão portuguesa da FMPS. MÉTODOS: A amostra foi constituída por 217 estudantes do ensino superior (178 mulheres). Um subgrupo (n = 166) completou o reteste após quatro semanas. RESULTADOS: A consistência interna da escala mostrou ser elevada (alfa de Cronbach = ,8 (more) 57). As correlações item-total corrigido variaram entre ,019 e ,548. Os resultados também sugeriram uma boa estabilidade temporal da escala, sendo a correlação teste-reteste de ,765. Foi realizada a análise das componentes principais com rotação Varimax e com base no Scree plot foram extraídas duas soluções fatoriais robustas (quatro e seis fatores). A análise paralela (Monte Carlo PCA) confirmou a solução de seis fatores. A validade concorrente com a escala MPS de Hewitt e Flett foi elevada, assim como a sua capacidade discriminante dos afetos positivos e negativos (Perfil de Estados de Humor - POMS). CONCLUSÃO: As duas estruturas fatoriais (quatro e seis fatores) encontradas na versão portuguesa da Escala Multidimensional de Perfeccionismo de Frost replicam os resultados obtidos por diferentes autores, em diferentes amostras e culturas. Esse fato sugere que essa escala é um instrumento robusto para a avaliação do perfeccionismo em vários contextos, clínicos e de investigação, bem como em estudos transculturais. Abstract in english BACKGROUND: The Frost Multidimensional Perfectionism Scale is one of the most world widely used measures of perfectionism. OBJECTIVE: To analyze the psychometric properties of the Portuguese version of the Frost Multidimensional Perfectionism Scale. METHODS: Two hundred and seventeen (178 females) students from two Portuguese Universities filled in the scale, and a subgroup (n = 166) completed a retest with a four weeks interval. RESULTS: The scale reliability was good (C (more) ronbach alpha = .857). Corrected item-total correlations ranged from .019 to .548. The scale test-retest reliability suggested a good temporal stability with a test-retest correlation of .765. A principal component analysis with Varimax rotation was performed and based on the Scree plot, two robust factorial structures were found (four and six factors). The principal component analyses, using Monte Carlo PCA for parallel analyses confirmed the six factor solution. The concurrent validity with Hewitt and Flett MPS was high, as well as the discriminant validity of positive and negative affect (Profile of Mood Stats-POMS). DISCUSSION: The two factorial structures (of four and six dimensions) of the Portuguese version of Frost Multidimensional Perfectionism Scale replicate the results from different authors, with different samples and cultures. This suggests this scale is a robust instrument to assess perfectionism, in several clinical and research settings as well as in transcultural studies.

Amaral, Ana Paula Monteiro; Soares, Maria João; Pereira, Ana Telma; Bos, Sandra Carvalho; Marques, Mariana; Valente, José; Nogueira, Vasco; Azevedo, Maria Helena; Macedo, António

2013-01-01

159

Study of a frost-less heat pump  

Energy Technology Data Exchange (ETDEWEB)

Heat pumps, used as primary residential space conditioning systems in many temperate climates, have inherent requirements for defrosting of the outdoor evaporator coil during the winter heating season when frost forms. This paper describes a new concept and the results of the new technology that minimizes evaporator coil frosting to ambient temperatures as low as 33 F, and that reduces or eliminates the need for reverse cycle defrosting at many conditions. By strategically adding controlled heat to the liquid stored in the accumulator, the evaporator temperature is increased. Depending on the amount of heat added, an evaporator temperature increase of 7 F can be realized. This increased coil temperature acts to decrease frosting in the ambient temperature range that has high frosting propensity, 33 F to 41 F. Proof-of-concept experiments were performed in both a baseline configuration and with the new frost-less technology on an of-the-shelf two-ton residential heat pump. Results are shown for outdoor air temperatures from 33 F to 41 F with relative humidity kept at 80%.

Domitrovic, R.E.; Chen, F.C.; Mei, V.C.; Murphy, R.W.; Kilpatrick, J.K.; Richardson, J.O.

1999-07-01

160

A frost formation model for cold isothermal walls and its validation for varying ambient conditions  

Energy Technology Data Exchange (ETDEWEB)

A general frost formation model was developed to calculate the frost weight and thickness on a cold isothermal surface subjected to varying environmental parameters. The restrictions of limited frost density and temperature ranges were essentially removed by development of a generalized correlation of the water frost thermal conductivity. The diffusion approach used by Brian et al. was extended to include the full range of frost density and temperatures and to include the water seepage phase of the frost growth. Careful attention was given to the heat and mass transfer coefficients for a given air flow regime and geometrical shape. The extended frost formation model was successful in predicting the frost growth for various published data.

Dietenberger, M.A.

1985-01-01

 
 
 
 
161

Statistical Examination of Frost Characterization: A Case of Global Warming Impact in Jordan  

Directory of Open Access Journals (Sweden)

Full Text Available Radiation and advection frost are common in Jordan as well as other neighboring countries as they face several frost waves each year during the late months of winter. Recently, many frost episodes hit the valley and damaged the crops that were compensated by millions of dollars by the Jordanian Government. This manuscript addresses and characterizes frost, and assesses the role of global warming in impacting frost in terms of its frequency, severity, and total number of frost days per year. A comprehensive statistical approach was used. The paper indicates that frost waves will continue to hit in the near future regardless of the fact that Earth is moving towards warmer conditions. Agricultural and financial authorities should be urged to minimize frost damage by considering installing wind fans in Jordan valley as an active method in addition to implementing good farm practices (as a passive methods where deemed necessary).

Moshrik R Hamdi; Mahmoud Abu Alaban; Mohammed Jaber

2011-01-01

162

The role of phenology in assessing risks of frost damage  

Science.gov (United States)

Climate warming in temperate regions has been shown to lengthen the summer growing season, both at the spring and autumn side, and shorten the winter season. Spring phenology, e.g. bud burst and leafing, is mainly triggered by forcing temperatures in order to maximize growing season during favorable conditions. Winter chilling and / or photoperiodic requirements prevent too early plant development related to a higher risk of damage by late spring frosts. The questions how risks of late spring frosts have been altered in the past and will change under future warming are discussed controversially in the current literature. In this paper we will take this classical example of vegetation - atmosphere interaction to demonstrate that traits of the species studied, the (partially) neglected status of the vegetation and regional climatic conditions may account for these differences reported. We suggest a methodology based on extreme value theory (EVT) to assess the frost risks and present results for continental Europe.

Menzel, Annette; Estrella, Nicole

2013-04-01

163

Frost sensor for use in defrost controls for refrigeration  

Energy Technology Data Exchange (ETDEWEB)

An apparatus and method for measuring the total thermal resistance to heat flow from the air to the evaporative cooler fins of a refrigeration system. The apparatus is a frost sensor that measures the reduction in heat flow due to the added thermal resistance of ice (reduced conduction) as well as the reduction in heat flow due to the blockage of airflow (reduced convection) from excessive ice formation. The sensor triggers a defrost cycle when needed, instead of on a timed interval. The invention is also a method for control of frost in a system that transfers heat from air to a refrigerant along a thermal path. The method involves measuring the thermal conductivity of the thermal path from the air to the refrigerant, recognizing a reduction in thermal conductivity due to the thermal insulation effect of the frost and due to the loss of airflow from excessive ice formation; and controlling the defrosting of the system.

French, Patrick D. (ADA Technologies, Inc. 8100 Shaffer Pkwy., Suite 130, Littleton, CO 80127-4107); Butz, James R. (ADA Technologies, Inc. 8100 Shaffer Pkwy., Suite 130, Littleton, CO 80127-4107); Veatch, Bradley D. (ADA Technologies, Inc. 8100 Shaffer Pkwy., Suite 130, Littleton, CO 80127-4107); O' Connor, Michael W. (ADA Technologies, Inc. 8100 Shaffer Pkwy., Suite 130, Littleton, CO 80127-4107)

2002-01-01

164

Bacterial ice nucleation: a factor in frost injury to plants.  

UK PubMed Central (United Kingdom)

Heterogeneous ice nuclei are necessary, and the common epiphytic ice nucleation active (INA) bacteria Pseudomonas syringae van Hall and Erwinia herbicola (Löhnis) Dye are sufficient to incite frost injury to sensitive plants at -5 degrees C. The ice nucleation activity of the bacteria occurs at the same temperatures at which frost injury to sensitive plants occurs in nature. Bacterial ice nucleation on leaves can be detected at about -2 degrees C, whereas the leaves themselves, i.e. without INA bacteria, contain nuclei active only at much lower temperatures. The temperature at which injury to plants occurs is predictable on the basis of the ice nucleation activity of leaf discs, which in turn depends on the number and ice nucleation activity of their resident bacteria. Bacterial isolates which are able to incite injury to corn at -5 degrees C are always active as ice nuclei at -5 degrees C. INA bacteria incited frost injury to all of the species of sensitive plants tested.

Lindow SE; Arny DC; Upper CD

1982-10-01

165

Design guide for frost-protected shallow foundations  

Energy Technology Data Exchange (ETDEWEB)

Frost-protected shallow foundations (FPSFs) offer a proven technology designed to substantially lower construction costs in colder climates, enhancing housing affordability for families in many parts of the United States. This document provides step-by-step procedures to assist building professionals in designing and laying a slab- on-grade FPSF. FPSFs save money over conventional designs by requiring less excavation to construct a frost-proof foundation. It is specially insulated along its perimeter to raise the temperature of the surrounding ground and decrease frost penetration, thus allowing for the construction of a substantially shallower foundation. The FPSF is considered standard practice for homes in Scandinavia, where 40 years of field testing has proven it to be economical to construct, durable, and energy efficient. HUD strongly encourages wide spread adoption of FPSF technology in the United States and its incorporation into major model building codes.

NONE

1994-10-01

166

No difference in frost hardiness between high and low altitude Pinus sylvestris (L.) offspring  

Energy Technology Data Exchange (ETDEWEB)

Seedlings representing offspring from 46 Swedish natural stands of Pinus sylvestris (L.) from latitude 63 degrees to 68 degrees and altitude 75 to 675 m were artificially frost hardened and tested for autumn frost hardiness using artificial freeze testing in a programmable freezing chamber. A clinal variation in frost hardiness was observed over latitude. Altitude has no effect on the frost hardiness. The results are discussed in relation to the reproduction- and migration biology of P. sylvestris. 21 refs, 3 figs, 1 tab

Sundblad, L.G.; Andersson, Bengt [The Forest Research Institute of Sweden, Saevar (Sweden)

1995-05-01

167

Measurement of frost characteristics on heat exchanger fins. Part 2: Data and analysis  

Energy Technology Data Exchange (ETDEWEB)

Part 1 of this paper described the frost growth test facility and instrumentation. In Part 2, results are presented for typical operating conditions with frost growth on heat exchanger fins. Typical data are presented for frost height distributions on fins, increase in pressure loss for airflow through a finned test section, frost mass accumulation on fins, and heat rate. Special attention is given to the uncertainty in each of these measurements and calculations.

Chen, H.; Thomas, L.; Besant, R.W.

1999-07-01

168

Experimental study on the effect of frost parameters on domestic refrigerator finned tube evaporator coils  

Energy Technology Data Exchange (ETDEWEB)

In this study, parameters affecting the frost formation on the evaporator of a refrigerator and the structure of frost were examined. Air velocity measurements both at the air inlet and outlet channels of the evaporator were performed, and the effect of air velocity on frost formation was examined. The rate of evaporation of water inside the refrigerator cabin was also recorded. (author)

OEzkan, Derya Burcu; OEzil, Eralp [Department of Mechanical Engineering, Yildiz Technical University, 34349 Istanbul (Turkey)

2006-12-15

169

Quantitative trait loci of frost tolerance and physiologically related trait in faba bean (Vicia faba L.)  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In faba bean, field based winter-hardiness is a complex trait that is significantly correlated to frost tolerance. Frost tolerance could be used to indirectly select for faba bean winter-hardiness. The aim of this study was to identify putative QTL associated with frost tolerance and auxiliary trait...

Arbaoui, Mustapha; Link, Wolfgang; Satovic, Zlatko; Torres, Ana-Maria

170

Risk analysis of first and last frost occurrences in central Alborz region, Iran  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Central Alborz is one of the important agricultural regions of Iran. Occurrence of the first frost in fall and the last frost in spring causes damage to the crops in this region every year. Information about the probable dates of frost occurrence helps farmers in preventing or reducing the damages c...

Rahimi, M.; Khalili, A.; Hajjam, S.; Kamali, G.A.; Stigter, C.J.

171

An Analysis of Life and Death in Robert Frost's Selected Poems  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Skripsi ini adalah penganalisisan puisi Robert Frost yang bertemakan hidup dan mati. Judul skripsi ini ialah An Analysis Of Life And Death In Robert Frost’s Selected Poems. Sanjak – sanjak yang dibahas ialah “Meeting and Passing”, “Nothing Gold Can Stay”, “After Apple Picking”, dan “Home Burial”.San...

Artika Sari, Dina

172

A method for assessing frost damage risk in sweet cherry orchards of South Patagonia  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Quantification of frost damage risk is important in planning the development of new orchard areas and for decision-making on design and installation of frost control systems. The objective of this study was to develop a comprehensive method to quantify frost damage risk in different sweet cherry pro...

Cittadini, E.D.; Ridder, N., de; Peri, P.L.; Keulen, H., van

173

Evaluation of host susceptibility, pathogen aggressiveness and sporangial survival in soil as factors affecting incidence of potato tuber infection by Phytophthora infestans in Ecuador  

Scientific Electronic Library Online (English)

Full Text Available Abstract in english Incidence of potato tuber infection by Phytophthora infestans is low in Ecuador. Factors considered to potentially affect the incidence of tuber infection include pathogen aggressiveness, host resistance, direct suppression from biological and chemical characteristics of soil acting on pathogen propagules, and exclusion resulting from soil structure and high ridging. In this study, we tested the hypothesis that low incidence could be due to reduced pathogen aggressiveness (more) and/or low host susceptibility by comparing several pathogen isolates and commonly grown potato cultivars from Ecuador with isolates and cultivars from Europe, where tuber blight is known to be a problem. Additionally, in Ecuador, whole tubers and slices of common varieties were inoculated with local isolates of P. infestans to test for potential infection under Ecuadorian conditions. All isolates, regardless of origin, caused tuber infection. The aggressiveness of isolates varied, but this was both between and among Ecuadorian and Swedish isolates and it was not possible to establish a clear difference in the degree of infection based on isolate origin, or origin of potato variety. In general, we found no evidence to suggest that low aggressiveness of the pathogen or extreme resistance of the host explains low incidence of tuber blight in Ecuador. Therefore, we conclude that low incidence of tuber blight in Ecuador is probably caused by soil factors. Furthermore, exclusion due to soil structure and high hilling may play an important role as a preliminary soil infectivity study demonstrated that P. infestans sporangia were infective in six Ecuadorian field soils for at least 15 days.

Oyarzún, Pedro J.; Krijger, Anna-Karin; Garzón, Carla D.; Leon, Diego; Kromann, Peter; Yuen, Jonathan E.; Forbes, Gregory A.

2011-06-01

174

Identificación de suelos susceptibles a riesgos de erosión y con mayor capacidad de almacenamiento de agua/ Identification of soils susceptible to risk erosion and with hight capacity of water storage  

Scientific Electronic Library Online (English)

Full Text Available Abstract in spanish La investigación se basó en el desarrollo de siete etapas metodológicas con criterios de integralidad, análisis holístico, secuencia lógica, participación y sencillez, destacándose los siguientes aspectos: Conceptualización y contextualización, muestreo de suelos, procesamiento de la información, espacialización de la información, identificación de zonas susceptibles a riesgos de erosión y con mayor capacidad de almacenamiento de agua, recomendaciones de ma (more) nejo y socialización de la investigación. La propuesta metodológica se validó y ajustó mediante un caso de estudio en la vereda Chicoral, subcuenca del río Bitaco, municipio de La Cumbre, Valle del Cauca, Colombia. Mediante procesos de participación y concertación con los actores socioeconómicos del área de estudio se lograron diagnosticar las causas y consecuencias que intervienen en procesos de degradación física del suelo y a la vez se localizaron los sitios con mayor potencialidad de almacenamiento de agua, factores importantes para la planificación y uso racional de los recursos naturales en una cuenca hidrográfica. Abstract in english The investigation was carried out in seven methodological steps under integral approaches, holistic analysis, logical sequence, participation and simplicity. The following aspects were highlighted: Conceptualization and contextualizacion, soil sampling , data processing, data spacializatión of the information, identification of susceptible areas to risk erosion with higher capacity of water storage, management norms and socialization of the investigation. The methodologi (more) cal proposal was validated and adjusted by a case of study in the rural areas of Chicoral, watershed of the Bitaco river, Municipality of La Cumbre, Cauca Valley, Colombia. Using participation processes and agreement with the communities of the study area, the diagnostic of the causes and consequences that intervene in processes of physical soil degradation were reached. At the same time, the places with higher potentiality of water storage were localized. All of these factors are important for planning and rational use of the natural resources in a watershed.

Henry, Velásquez Valencia; Menjivar, Juan Carlos; Escobar, Carlos Alberto

2007-09-01

175

Identification of soils susceptible to risk erosion and with hight capacity of water storage Identificación de suelos susceptibles a riesgos de erosión y con mayor capacidad de almacenamiento de agua  

Directory of Open Access Journals (Sweden)

Full Text Available The investigation was carried out in seven methodological steps under integral approaches, holistic analysis, logical sequence, participation and simplicity. The following aspects were highlighted: Conceptualization and contextualizacion, soil sampling , data processing, data spacializatión of the information, identification of susceptible areas to risk erosion with higher capacity of water storage, management norms and socialization of the investigation. The methodological proposal was validated and adjusted by a case of study in the rural areas of Chicoral, watershed of the Bitaco river, Municipality of La Cumbre, Cauca Valley , Colombia. Using participation processes and agreement with the communities of the study area, the diagnostic of the causes and consequences that intervene in processes of physical soil degradation were reached. At the same time, the places with higher potentiality of water storage were localized. All of these factors are important for planning and rational use of the natural resources in a watershed.La investigación se basó en el desarrollo de siete etapas metodológicas con criterios de integralidad, análisis holístico, secuencia lógica, participación y sencillez, destacándose los siguientes aspectos: Conceptualización y contextualización, muestreo de suelos, procesamiento de la información, espacialización de la información, identificación de zonas susceptibles a riesgos de erosión y con mayor capacidad de almacenamiento de agua, recomendaciones de manejo y socialización de la investigación. La propuesta metodológica se validó y ajustó mediante un caso de estudio en la vereda Chicoral, subcuenca del río Bitaco, municipio de La Cumbre, Valle del Cauca, Colombia. Mediante procesos de participación y concertación con los actores socioeconómicos del área de estudio se lograron diagnosticar las causas y consecuencias que intervienen en procesos de degradación física del suelo y a la vez se localizaron los sitios con mayor potencialidad de almacenamiento de agua, factores importantes para la planificación y uso racional de los recursos naturales en una cuenca hidrográfica.

Velasquez Valencia Henry; Menjivar Juan Carlos; Escobar Chalarca Carlos Alberto

2007-01-01

176

Identificación de suelos susceptibles a riesgos de erosión y con mayor capacidad de almacenamiento de agua Identification of soils susceptible to risk erosion and with hight capacity of water storage  

Directory of Open Access Journals (Sweden)

Full Text Available La investigación se basó en el desarrollo de siete etapas metodológicas con criterios de integralidad, análisis holístico, secuencia lógica, participación y sencillez, destacándose los siguientes aspectos: Conceptualización y contextualización, muestreo de suelos, procesamiento de la información, espacialización de la información, identificación de zonas susceptibles a riesgos de erosión y con mayor capacidad de almacenamiento de agua, recomendaciones de manejo y socialización de la investigación. La propuesta metodológica se validó y ajustó mediante un caso de estudio en la vereda Chicoral, subcuenca del río Bitaco, municipio de La Cumbre, Valle del Cauca, Colombia. Mediante procesos de participación y concertación con los actores socioeconómicos del área de estudio se lograron diagnosticar las causas y consecuencias que intervienen en procesos de degradación física del suelo y a la vez se localizaron los sitios con mayor potencialidad de almacenamiento de agua, factores importantes para la planificación y uso racional de los recursos naturales en una cuenca hidrográfica.The investigation was carried out in seven methodological steps under integral approaches, holistic analysis, logical sequence, participation and simplicity. The following aspects were highlighted: Conceptualization and contextualizacion, soil sampling , data processing, data spacializatión of the information, identification of susceptible areas to risk erosion with higher capacity of water storage, management norms and socialization of the investigation. The methodological proposal was validated and adjusted by a case of study in the rural areas of Chicoral, watershed of the Bitaco river, Municipality of La Cumbre, Cauca Valley, Colombia. Using participation processes and agreement with the communities of the study area, the diagnostic of the causes and consequences that intervene in processes of physical soil degradation were reached. At the same time, the places with higher potentiality of water storage were localized. All of these factors are important for planning and rational use of the natural resources in a watershed.

Velásquez Valencia Henry; Juan Carlos Menjivar; Carlos Alberto Escobar

2007-01-01

177

Frost protection: fundamentals, practice and economics. Volume 1  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This book describes the physics and biology of frost occurrence and damage, passive and active protection methods and how to access the cost-effectiveness of active protection techniques. Night-time energy balanceis used to demonstrate how protection methods are used to reduce the likelihood of fros...

Snyder, Richard L.; Melo-Abreu, J. Paulo

178

Reducing Frost of Broad Bean by Controling Ice Nucleation Bacteria  

UK PubMed Central (United Kingdom)

Based on the results from field, five optional preparations (No.1, No.3, No.4, No.5 and No.10) were chosen to control ice nucleation active so as to reduce frost of broad bean with stable effect. Among the preparations, No.5 was developed largely because it increased broad bean production by 10% ? 20%.

Zhang Shiguang; Luo Youzhen; Hu Aiming; Ji Guanghai; Wei Jianfu; Chen Xingquan; Dong Wenhan

2002-01-01

179

Frost-protected shallow foundations. Phase 2. Final report  

Energy Technology Data Exchange (ETDEWEB)

Frost-protected shallow foundations (FPSFs) offer a proven technology designed to substantially lower construction costs in colder climates, enhancing housing affordability for families in many parts of the United States. This document provides step-by-step procedures to assist building professionals in designing and laying a slab-on-grade FPSF.

Crandell, J.H.; Lund, E.M.; Bruen, M.G.; Nowak, M.S.

1994-06-01

180

Increasing the frost resistance of facade glazed tiles  

Energy Technology Data Exchange (ETDEWEB)

The authors investigate the protective properties of a coating of boron oxides and zirconium oxides applied as a glaze to ceramic tiles by conducting a series of tests to determine the frost resistance, the propensity to absorb water, the moisture expansion coefficient, the fracture behavior, and the effect of thermal cycling on the oxides. Results are graphed and tabulated.

Egerev, V.M.; Zotov, S.N.; Romanova, G.P.

1986-09-01

 
 
 
 
181

A transient analysis of frost formation on a parallel plate evaporator  

Energy Technology Data Exchange (ETDEWEB)

This paper presents the development of a transient model for evaluating frost formation on a parallel plate evaporator for heat pump applications. The model treats the frost layer as a porous substance, and applies the equations of conservation of mass, momentum and energy to calculate the growth and densification of the frost layer. Empirical correlations for thermal conductivity and tortuosity as a function of density are incorporated from previous studies. Frost growth is calculated as a function of time, Reynolds number, longitudinal location, plate temperature, and ambient air temperature and humidity. The main assumptions are: ideal gas behavior for air and water vapor, uniform frost density and thermal conductivity across the thickness of the frost layer; and quasi-steady conditions during the whole process. The mathematical model is validated by comparing the predicted values of frost thickness and frost density with results obtained in recent experimental studies. A good agreement was obtained in the comparison. The frost formation model calculates pressure drop and heat transfer resistance that result from the existence of the frost layer, and it can therefore be incorporated into a heat pump model to evaluate performance losses due to frosting as a function of weather conditions and time of operation since the last evaporator defrost.

Martinez-Frias, J.; Aceves, S.M.; Hernandez-Guerrero, A. [Univ. of Guanajuato (Mexico). Dept. of Mechanical Engineering

1996-12-31

182

Foundations in permafrost and seasonal frost  

Energy Technology Data Exchange (ETDEWEB)

This book contains the following papers: Artic foundation selection: A decision matrix; Standards for pile load tests in permafrost; Attenuating creep of piles in frozen soils; Creep of a strip footing on ice-rich permafrost; and Snow effects on pile design temperatures.

Wuori, A.; Sayles, F.H.

1985-01-01

183

Predicting Frost Resistance of Concrete with Different Coarse Aggregate Concentration by Porosity Parameters  

Directory of Open Access Journals (Sweden)

Full Text Available Frost resistance is one of the key indicators of concrete quality. Frost resistance can be determined by direct testing; however it is time-consuming and labour-intensive method. Concrete decomposition is a complex process (from initial signs of degradation to complete failure of the surface subjected to freezing) involving many factors. Frost resistance of concrete can be predicted from porosity parameters after determining their relation to frost resistance. Test results showed the relation between the closed porosity of concrete and frost resistance factor. Closed porosity of concrete was found to have a significant influence on frost resistance factor. It is shown that closed porosity depends on the concentration of coarse aggregate in concrete, the closed porosity and predicted frost resistance of concrete increase with lower concentration of coarse aggregate.http://dx.doi.org/10.5755/j01.ms.17.2.493

Džigita NAGROCKIEN?; Gintautas SKRIPKI?NAS; Giedrius GIRSKAS

2011-01-01

184

Frost behavior of a fin surface with temperature variation along heat exchanger fins  

International Nuclear Information System (INIS)

This paper presents a mathematical model for predicting the frost behavior formed on heat exchanger fins, considering fin heat conduction under frosting condition. The model is composed of air-side, the frost layer, and fin region, and they are coupled to the frost layer. The frost behavior is more accurately predicted with fin heat conduction considered (Case A) than with a constant fin surface temperature assumed (Case B). The results indicate that the frost thickness and heat transfer rate for Case B are over-predicted in most regions of the fin, as compared to those for Case A. Also, for Case A, the maximum frost thickness varies little with the fin length variations, and the extension of the fin length over 30 mm contributes insignificantly to heat transfer

2007-06-01

185

Analysis of early-stage frost formation in natural convection over a horizontal cylinder  

Energy Technology Data Exchange (ETDEWEB)

Frost growth process on a cold surface consists of two stages: The early-stage or one-dimensional growth of ice columns and multidimensional growth in the form of a porous structure. The transition time which marking these two stages is important for any numerical modeling of frost formation. This paper proposes a mathematical model to predict the transition time and frost properties in natural convection of frost formation over a cooled horizontal cylinder in the first stage of growth period. Comparison is performed among the results of this model and experimental observations reported in the literatures. It is observed that the presented model can be used more efficiently to determine transition time and frost properties in the early-stage of frost formation. Based on the obtained results a new correlation is developed for the duration time of early-stage of frost formation process (transition time) in natural convection. (author)

Tahavvor, Ali R. [School of Engineering, Shiraz University, Shiraz 71348-51154 (Iran); Yaghoubi, Mahmood [School of Engineering, Shiraz University, Shiraz 71348-51154 (Iran); Academy of Sciences (Iran)

2009-09-15

186

Is shade beneficial for mediterranean shrubs experiencing periods of extreme drought and late-winter frosts?  

UK PubMed Central (United Kingdom)

BACKGROUND AND AIMS: Plants are naturally exposed to multiple, frequently interactive stress factors, most of which are becoming more severe due to global change. Established plants have been reported to facilitate the establishment of juvenile plants, but net effects of plant-plant interactions are difficult to assess due to complex interactions among environmental factors. An investigation was carried out in order to determine how two dominant evergreen shrubs (Quercus ilex and Arctostaphylos uva-ursi) co-occurring in continental, Mediterranean habitats respond to multiple abiotic stresses and whether the shaded understorey conditions ameliorate the negative effects of drought and winter frosts on the physiology of leaves. METHODS: Microclimate and ecophysiology of sun and shade plants were studied at a continental plateau in central Spain during 2004-2005, with 2005 being one of the driest and hottest years on record; several late-winter frosts also occurred in 2005. KEY RESULTS: Daytime air temperature and vapour pressure deficit were lower in the shade than in the sun, but soil moisture was also lower in the shade during the spring and summer of 2005, and night-time temperatures were higher in the shade. Water potential, photochemical efficiency, light-saturated photosynthesis, stomatal conductance and leaf 13C composition differed between sun and shade individuals throughout the seasons, but differences were species specific. Shade was beneficial for leaf-level physiology in Q. ilex during winter, detrimental during spring for both species, and of little consequence in summer. CONCLUSIONS: The results suggest that beneficial effects of shade can be eclipsed by reduced soil moisture during dry years, which are expected to be more frequent in the most likely climate change scenarios for the Mediterranean region.

Valladares F; Zaragoza-Castells J; Sánchez-Gómez D; Matesanz S; Alonso B; Portsmuth A; Delgado A; Atkin OK

2008-12-01

187

Susceptibilidad del suelo a la degradación en parcelas con manejo agroforestal Quesungual en Nicaragua/ Susceptibility to soil degradation in plots under Quesungual agroforestry management in Nicaragua  

Scientific Electronic Library Online (English)

Full Text Available Abstract in spanish Durante tres años se establecieron en un Andisol del municipio de Somotillo (Nicaragua) los sistemas de usos de tierra: tradicional del productor (tala, quema, fertilización y siembra de maíz + fríjol); agroforestal Quesungual (SAQ) (no quema, árboles nativos en regeneración natural y siembra de maíz + fríjol); residuos de cultivos (manejo de cobertura con residuos de cultivos); y testigo bosque secundario (tacotal) de aproximadamente cinco años de edad no cultiv (more) ado. Se hicieron muestreos de suelos a profundidades de 0-5, 5-10 y 10-20 cm para caracterización física y de fertilidad y estimación de la erosión hídrica por simulación. Los sistemas Quesungal y Residuos de Cultivo, mantuvieron la susceptibilidad del suelo a la erosión en niveles tan bajos como los del bosque natural secundario. Abstract in english In an andisol tt was placed for three years land uses systems like: farmer traditional (slash and burn, fertilization and sowing of bean and maiz); Quesungual Agroforestry System-SAQ (no burn, natural regeneration of native trees, bean and maiz sowing); crop residues as management cover, and a fi ve years secundary forest (tacotal) as a control. It was considered soil samples at 0-5, 5-10 y 10-20 for physical and fertility characterization and field measurement of soil er (more) osion by rain simulation. Quesungal and crop residues systems, remained soil erosión susceptibility at levels as low as the natural secondary forest.

Pavón T, Jellín del Carmen; Madero M, Edgar; Amézquita C, Edgar

2010-01-01

188

Susceptibilidad del suelo a la degradación en parcelas con manejo agroforestal Quesungual en Nicaragua Susceptibility to soil degradation in plots under Quesungual agroforestry management in Nicaragua  

Directory of Open Access Journals (Sweden)

Full Text Available Durante tres años se establecieron en un Andisol del municipio de Somotillo (Nicaragua) los sistemas de usos de tierra: tradicional del productor (tala, quema, fertilización y siembra de maíz + fríjol); agroforestal Quesungual (SAQ) (no quema, árboles nativos en regeneración natural y siembra de maíz + fríjol); residuos de cultivos (manejo de cobertura con residuos de cultivos); y testigo bosque secundario (tacotal) de aproximadamente cinco años de edad no cultivado. Se hicieron muestreos de suelos a profundidades de 0-5, 5-10 y 10-20 cm para caracterización física y de fertilidad y estimación de la erosión hídrica por simulación. Los sistemas Quesungal y Residuos de Cultivo, mantuvieron la susceptibilidad del suelo a la erosión en niveles tan bajos como los del bosque natural secundario.In an andisol tt was placed for three years land uses systems like: farmer traditional (slash and burn, fertilization and sowing of bean and maiz); Quesungual Agroforestry System-SAQ (no burn, natural regeneration of native trees, bean and maiz sowing); crop residues as management cover, and a fi ve years secundary forest (tacotal) as a control. It was considered soil samples at 0-5, 5-10 y 10-20 for physical and fertility characterization and field measurement of soil erosion by rain simulation. Quesungal and crop residues systems, remained soil erosión susceptibility at levels as low as the natural secondary forest.

Jellín del Carmen Pavón T; Edgar Madero M; Edgar Amézquita C

2010-01-01

189

Modelos de paisagem e susceptibilidade magnética na identificação e caracterização do solo/ Landscape models and magnetic susceptibility on soil identification and characterization  

Scientific Electronic Library Online (English)

Full Text Available Abstract in portuguese O conhecimento detalhado do solo e de seus atributos, ao longo da paisagem, é uma demanda permanente dos sistemas urbanos e agroindustriais, para o planejamento sustentável de uso e ocupação. O presente trabalho objetivou estudar o potencial de modelos de paisagem e susceptibilidade magnética na identificação e caracterização de latossolos, em Guariba (SP). Foram coletadas 514 amostras de solo, em 110,0 ha, às profundidades de 0,0-0,20 m e 0,60-0,80 m. Foram ide (more) ntificados diferentes compartimentos de paisagem, com base no modelo de superfície geomórfica e segmento de vertente. Em cada compartimento de paisagem, foram abertas trincheiras, para classificação do solo. As amostras foram analisadas quanto à granulometria e atributos químicos, pH (água, CaCl2 e KCl), matéria orgânica, P extraível, K+, Ca2+, Mg2+ e H+ + Al3+. Também foram determinados os teores de SiO2, Al2O3, Fe2O3 e óxidos de Fe livres (Fe d) e pouco cristalizados (Fe o), nas amostras das trincheiras, além da susceptibilidade magnética (SM). Solos taxonomicamente iguais, porém em diferentes compartimentos da paisagem, apresentaram valores distintos, para os atributos estudados, indicando que os modelos de paisagem e a susceptibilidade magnética podem ser viáveis, como técnica de campo, para auxiliar no detalhamento da variação dos atributos do solo. A susceptibilidade magnética demonstrou ter potencial para delimitação das superfícies geomórficas mapeadas no campo, o que indica o seu potencial de uso, na identificação e caracterização de áreas mais homogêneas. Abstract in english The detailed knowledge of soils and their attributes, across the landscape, is a permanent demand of urban and agro-industrial systems, for planning their sustainable use and occupation. This study aimed at evaluating the potential of landscape models and the magnetic susceptibility in the identification and characterization of oxisols, in Guariba, São Paulo State, Brazil. A total of 514 soil samples were collected in 110.0 ha, at the depths of 0.0-0.20 m and 0.60-0.80 m (more) . Different landscape compartments, based on the geomorphic surface and segment slope models, were identified. In each landscape compartment, trenches were opened for soil classification. The samples were analyzed for particle size and chemical properties, pH (water, CaCl2 and KCl), organic matter, extractable P, K+, Ca2+, Mg2+ and H+ + Al3+. The contents of SiO2, Al2O3, Fe2O3 and free (Fe d) and slightly crystallized (Fe o) Fe oxides were determined in samples from the trenches, as well as the magnetic susceptibility (MS). Taxonomically similar soils, but in different landscape compartments, presented different values for the attributes studied, indicating that the landscape models and magnetic susceptibility may be viable, as a field technique, to help detailing the variation of soil attributes. The magnetic susceptibility showed potential for delimiting geomorphic surfaces mapped in the field, emphasizing its potential use for identifying and characterizing homogeneous areas.

Matias, Sammy Sidney Rocha; Marques Júnior, José; Siqueira, Diego Silva; Pereira, Gener Tadeu

2013-03-01

190

Influences of surface hydrophilicity on frost formation on a vertical cold plate under natural convection conditions  

Energy Technology Data Exchange (ETDEWEB)

Surface hydrophilicity has a strong influence on frost nucleation according to phase transition theory. To study this effect, a close observation of frost formation and deposition processes on a vertical plate was made under free convection conditions. The formation and shape variation of frost crystals during the initial period are described and the frost thickness variation with time on both hydrophobic and plain copper cold surfaces are presented. The various influencing factors are discussed in depth. The mechanism of surface hydrophilicity influence on frost formation was analyzed theoretically. This revealed that increasing the contact angle can increase the potential barrier and restrain crystal nucleation and growth and thus frost deposition. The experimental results show that the initial water drops formed on a hydrophobic surface are smaller and remain in the liquid state for a longer time compared with ones formed on a plain copper surface. It is also observed that the frost layer deposited on a hydrophobic surface is loose and weak. Though the hydrophobic surface can retard frost formation to a certain extent and causes a looser frost layer, our experimental results show that it does not depress the growth of the frost layer. (author)

Liu, Zhongliang; Zhang, Xinghua; Wang, Hongyan; Meng, Sheng; Cheng, Shuiyuan [Key Laboratory of Enhanced Heat Transfer and Energy Conservation, Ministry of Education and Key Laboratory of Heat Transfer and Energy Conversion, Beijing Education Commission, College of Environmental and Energy Engineering, Beijing University of Technology, Pingleyuan 100, Beijing 100022 (China)

2007-07-15

191

Difference in characteristics between parallel and counter flow type heat exchangers with frosting  

Energy Technology Data Exchange (ETDEWEB)

On heat exchangers which involve frosting, frost growth greatly varies depending on time and the location of the heat exchanger. This means that the thermal resistance of a heat exchanger varies with time and its location. When investigating the efficiency of a heat exchanger, it is important to understand frost layer variations with locations and frost growth variations with time. Experiments using a frost layer structure model were conducted, and the results were analyzed. The findings are as follows: An experimental formula which can apply in a wide range of initial conditions necessary for theoretical analysis of frost growth was obtained. This formula has made it possible to calculate frost growth under various conditions. In heat exchangers, the thermal resistance in parallel flow is higher in the upstream area where the amount of stuck frost is larger, whereas the thermal resistance in counterflow is lower in the upstream area than in the downstream area. In general, the average thermal resistance per unit amount of stuck frost is higher in counterflow than in parallel flow, and the difference in temperature efficiency between parallel flow and counterflow is lower when the amount of stuck frost is larger. (14 figs, 1 tab, 4 refs)

Aoki, Kazuo; Hattori, Masaru; Mizuno, Satoru

1988-07-25

192

When are fetuses and young children most susceptible to soil metal concentrations of arsenic, lead and mercury?  

UK PubMed Central (United Kingdom)

This study was designed to analyze when, during pregnancy and early childhood, the association between soil metal concentrations of arsenic (As), lead (Pb) and mercury (Hg) and the outcome of intellectual disability (ID) is statistically significant. Using cluster analysis, we identified ten areas of land that contained a cluster of ID and areas of average risk for ID. We analyzed soil for As, Pb, and Hg and estimated the soil metal concentration at the residential sites where the woman and children lived during pregnancy and early childhood using a Bayesian Kriging model. Arsenic concentrations were associated with ID during the first trimester of pregnancy and Hg was associated with ID early in pregnancy and the first two years of childhood. The covariates that remained in the final models were also temporally associated with ID.

McDermott S; Bao W; Marjorie Aelion C; Cai B; Lawson A

2012-09-01

193

Assessment of the chloride migration coefficient, internal frost resistance, salt frost scaling and sulphate resistance of self-compacting concrete : with some interrelated properties  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This report describes laboratory and analytical studies of the chloride migration coefficient, D, defined by Tang, the salt frost scaling, the internal frost resistance and the sulphate resistance of SCC that contains increased amount of filler, different types of casting and different air content.

Persson, Bertil

194

FROST: an ASIC for digital mammography with synchrotron radiation  

International Nuclear Information System (INIS)

The FRONTier RADiography (FRONTRAD) collaboration is developing a digital system for mammography at the Elettra Synchrotron Light Source in Trieste. The system is based on a silicon microstrip detector array. The ASIC FROST (FRONTRAD Read Out sySTem) was developed as a collaboration between INFN Trieste and Aurelia Microelettronica and is designed to operate in single photon counting mode. FROST provides low-noise and high-gain performances and is able to work at incident photon rates higher than 100 kHz with almost 100% efficiency. The ASIC has been tested and the first images of mammographic test objects will be shown. The acquisition time per breast image should be of about 10 s.

2003-09-01

195

Thermofluid characteristics of frosted finned-tube heat exchangers  

Energy Technology Data Exchange (ETDEWEB)

The performance of frosted finned-tube heat exchangers of different fin types is investigated by experiments in this paper. The effects of the air flow rate, the air relative humidity, the refrigerant temperature, and the fin type on the thermofluid characteristics of the heat exchangers are discussed. The time variations of the heat transfer rate, the overall heat transfer coefficient, and the pressure drop of the heat exchangers are presented. The heat transfer rate, the overall heat transfer coefficient, and the pressure drop for heat exchangers with re-direction louver fins are higher than those with flat plate fins and one-sided louver fins are. The amount of frost formation is the highest for heat exchangers with re-direction louver fins. (author)

Wei-Mon Yan; Hung-Yi Li [Huafan University, Taipei (Taiwan). Department of Mechatronical Engineering; Yeong-Ley Tsay [National Huwei Institute of Technology, Yunlin (Taiwan). Department of Aeronautical Engineering

2005-07-01

196

Gamma-ray spectrometry, electrical resistivity, and magnetic susceptibility of agricultural soils in the Northwest region of the Parana State, Brazil; Gamaespectrometria, resistividade eletrica e susceptibilidade magnetica de solos agricolas no noroeste do estado do Parana  

Energy Technology Data Exchange (ETDEWEB)

Gamma-ray spectrometry, electrical resistivity, and magnetic susceptibility measurements were taken from agricultural areas near the City of Maringa, in the Northwest region of the Parana state, south Brazil, in order to characterize the spatial distribution of radionuclides (K, eU, and eTh), the apparent resistivity, and the magnetic susceptibility determined for soils. Three different types of soils are present in this agricultural area: Alfisoil, clayey texture Oxisoil, both deriving from Lower Cretaceous basalts of the Serra Geral Formation; and medium texture Oxisoil from reworked Serra Geral and Goio-Ere formations, the latter deriving from sandstones of the Upper Cretaceous Caiua Group. It could be observed that in more clayey soils both concentration of radionuclides and susceptibility values are higher than in more sandy soils, especially due to the higher adsorption in the former and to the higher availability of magnetic minerals in the latter. The average ppm and Bq Kg{sup -1} grades for K, eU, and eTh in the areas under anthropic activity are of 1766-54.75, 0.83-10.22, and 1.78-7.27, respectively. These grades are significantly higher than those of non-occupied or non-fertilized areas (1101-34.15 K, 0.14-1.69 eU, and 1.31-5.36 eTh in ppm and Bq Kg-1, respectively.) Correlations were observed between uranium and clay, uranium and magnetic susceptibility, uranium and organic matter, and between electric resistivity and clay grades. Varied concentrations of radionuclides were also observed in different fertilizer formulations applied to soy and wheat cultures. Apparent electric resistivity values between 25 and 647 Ohm.m and magnetic susceptibility values between 0.28 e 1.10 x 10-3 SI due to clay and magnetic minerals represented important soil discrimination factors in the study area that can be incorporated as easy, low-cost soil mapping tools. (author)

Becegato, Valter Antonio [Universidade do Estado de Santa Catarina-UDESC, Centro de Ciencias Agroveterinarias, Lages, SC (Brazil); Ferreira, Francisco Jose Fonseca, E-mail: becegato@cav.udesc.br, E-mail: francisco.ferreira@ufpr.br [Universidade Federal do Parana (LPGA/UFPR), Curitiba, PR (Brazil). Dept. de Geologia. Lab. de Pesquisas em Geofisica Aplicada

2005-10-15

197

Influence of coffee pruning on the severity of frost damage  

Directory of Open Access Journals (Sweden)

Full Text Available Frost damages in a field experiment of pruning types and systems for the cultivars of Coffea arabica Catuaí and Mundo Novo, were evaluated at Londrina (23º22’S, 52º10´W), State of Parana, southern Brazil, during the winter of 1990 and 1994. Pruning types evaluated were ‘esqueletamento’ (cutting off all plagiotropic branches at 20-30 cm from the orthotropic branch), ‘decote’ (cutting off the orthotropic branch at 1.5 m and 2.0 m above ground) and ‘recepa’ (cutting off the orthotropic branch at 0.8 m above ground), performed on all rows and on alternate rows, and on different sections of the plant. Results indicated that frost damage could increase according to the type and height of pruning. The pruning type ‘esqueletamento’ and prunings at higher levels were more suitable for regions with frost risk. Under severe frost condition, pruning type did not affect the damage in anyone of the treatments evaluated.Foram avaliados os danos causados pelas geadas ocorridas em 1990 e 1994 em cafeeiros de duas cultivares de Coffea arabica L., Catuaí e Mundo Novo, conduzidos em Londrina-PR. Os tipos e sistemas de podas aplicados foram o esqueletamento a 20-30 cm do tronco, decote a 1,5 m e 2,0 m de altura e recepa a 0,80 m de altura. As podas foram feitas em área total e em linhas alternadas e em diferentes partes da planta. Os dados obtidos indicaram que os danos por geada podem ser intensificados em função do tipo e altura da poda. A poda do tipo esqueletamento e as podas altas são mais indicadas para o manejo das lavouras nas regiões mais sujeitas ao fenômeno de geada. No caso de geada severa, todos os cafeeiros foram afetados, independente do tipo de poda.

Armando Androcioli Filho; Paulo Henrique Caramori

2000-01-01

198

Climate Change Shifts Frost Seasons and Plant Growth  

Science.gov (United States)

This month's issue of Ecology Letters adds new evidence to the effect of climate change on ecosystems. In a paper by Professor of Biology Dr. David Inouye of the University of Maryland, global climate change appears to influence early and late frost events, which in turn, "inhibit growth and possibly damage many plants." This news brief from ScienceDaily.com describes the recent finding and comments on its wider significance.

199

The frost peat production; Routapalaturpeen tuotantoketjun tekniikka, talous ja ympaeristoevaikutukset  

Energy Technology Data Exchange (ETDEWEB)

The frost peat production means the cutting of frozen peat in the winter time. The aim of this study is to test the possibilities to prolong the peat production season and to produce peat pieces for the horticultural peat industry. In the frost peat production method the frozen peat field is sawed throughout the length and breadth of by a circle saw. The sawed peat pieces are loosened from the field by a so-called `splitter`. The circle saw is equipped with the five circle saw blades (diameter 90 cm). The distance of the blades is adjustable. The splitter is equipped with a horizontal position blade (width 35 cm). The dimensions of the peat pieces are changeable, but from the point of drying the upper limit of the side of the peat cube can be 15-20 cm. The frost peat production method is technically suitable for production of slightly decomposed (H1-5) energy and horticultural peat. The energy peat pieces are allowed to dry up 70-75 % moisture content on the cutting field and then the pieces can be ridged by the screening ridger. If necessary, the ridges can be turned over. In the frost peat production, the conventional sod peat winning machines can be used in the following stages of the working tasks: harrowing, ridging, loading, turning of ridges and stockpiling. The measured output of the circle saw was about 45-50 m{sup 3}/h of energy peat and 58-63 m{sup 3}/h of horticultural peat. The output of the splitter was 120-150 m{sup 3}/h. Theoretically, the output of circle saw and the splitter can easily be doubled. Thereafter the production costs will be about 19 FIM/MWh of energy peat and 18,6 FIM/m{sup 3} of horticultural peat

Nyroenen, T. [Vapo Oy, Jyvaeskylae (Finland); Leiviskae, V. [Oulu Univ. (Finland). Thule Inst.

1997-12-01

200

Bacterial ice nucleation: a factor in frost injury to plants.  

Science.gov (United States)

Heterogeneous ice nuclei are necessary, and the common epiphytic ice nucleation active (INA) bacteria Pseudomonas syringae van Hall and Erwinia herbicola (Löhnis) Dye are sufficient to incite frost injury to sensitive plants at -5 degrees C. The ice nucleation activity of the bacteria occurs at the same temperatures at which frost injury to sensitive plants occurs in nature. Bacterial ice nucleation on leaves can be detected at about -2 degrees C, whereas the leaves themselves, i.e. without INA bacteria, contain nuclei active only at much lower temperatures. The temperature at which injury to plants occurs is predictable on the basis of the ice nucleation activity of leaf discs, which in turn depends on the number and ice nucleation activity of their resident bacteria. Bacterial isolates which are able to incite injury to corn at -5 degrees C are always active as ice nuclei at -5 degrees C. INA bacteria incited frost injury to all of the species of sensitive plants tested. PMID:16662618

Lindow, S E; Arny, D C; Upper, C D

1982-10-01

 
 
 
 
201

Suscetibilidade magnética do horizonte B de solos do Estado do Paraná Magnetic susceptibility of B horizon of soils in the State of Paraná  

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Full Text Available Os minerais ferrimagnéticos maghemita (?Fe2O3) e magnetita (Fe3O4) possuem alta relação com a disponibilidade de cátions metálicos e com a capacidade do solo em adsorver ânions como o fosfato. Uma percentagem expressiva dos solos brasileiros apresenta magnetização espontânea. No Estado do Paraná essa área corresponde a aproximadamente 50 %. A determinação da suscetibilidade magnética por unidade de massa (?BF) é o método mais simples de identificar a presença e quantificar esses minerais nos solos. A BF é uma técnica rápida, barata, não destrutiva e de boa reprodutibilidade, que pode ser utilizada como critério nos estudos pedogenéticos em que os minerais ferrimagnéticos estão presentes. O objetivo deste trabalho foi verificar a influência do material de origem nos valores de ?BF da terra fina seca ao ar (TFSA) de amostras do horizonte B de solos do Paraná. As amostras foram coletadas em todo o Estado, num total de 45 pontos. Na TFSA foram determinados os valores de BF e da porcentagem da frequência dependente da suscetibilidade magnética (?FD). Os valores de suscetibilidade magnética dos solos formados sobre rochas eruptivas básicas foram significativamente maiores (1.000 a 7.800 x 10-8 m³ kg-1) que os encontrados em solos formados sobre rochas metamórficas e sedimentares (menores do que 500 x 10-8 m³ kg-1), demonstrando a influência do material de origem na presença de minerais ferrimagnéticos. Os valores de ?FD indicaram a presenca de partículas superparamagnéticas (maghemita) na maioria dos solos paranaenses.The ferrimagnetic minerals maghemite (?Fe2O3) are closely related with metal availability and P adsorption capacity. Magnetization is spontaneous in a significant percentage of Brazilian soils. In the State of Paraná (Brazil) this area represents up to 50 %. The determination of the mass-specific magnetic susceptibility (?BF) is the simplest method of identification and quantification of ferrimagnetic minerals in soils. The ?LF is a quick, cheap, non-destructive technique, with satisfactory reproducibility, and can be used as a criterion in pedogenetic studies involving ferrimagnetic minerals. The aim of this paper was to verify the influence of parent rock material on ?LF values of air-dried fine earth of B horizon of soil samples from Paraná. The samples were collected at 45 sites across the entire State to determine the ?LF values and percentage of frequency-dependent magnetic susceptibility (?FD). The values of mass-specific magnetic susceptibility of soils formed from basic eruptive rocks were significantly higher (1,000 to 7,800 x 10-8 m³ kg-1) than of those from sedimentary and metamorphic rocks (lower than 500 x 10-8 m³ kg-1). The data show the strong influence of the parent rock material on the presence of ferrimagnetic minerals. The ?FD values indicate the presence of superparamagnetic particles (maghemite) in the majority of the Paraná State soils.

Alceu Rodrigues da Silva; Ivan Granemann de Souza Junior; Antonio Carlos Saraiva da Costa

2010-01-01

202

A new model for predicting performance of fin-and-tube heat exchanger under frost condition  

International Nuclear Information System (INIS)

Accurate prediction of frost characteristics has crucial influence on designing effective heat exchangers. In this paper, a new CFD (Computational Fluid Dynamics) model has been proposed to predict the frost behaviour. The initial period of frost formation can be predicted and the influence of surface structure can be considered. The numerical simulations have been carried out to investigate the performance of fin-and-tube heat exchanger under frost condition. The results have been validated by comparison of simulations with the data computed by empirical formulas. The transient local frost formation has been obtained. The average frost thickness, heat exchanger coefficient and pressure drop on air side has been analysed as well. In addition, the influence factors have also been discussed, such as fin pitch, relative humidity, air flow rate and evaporating temperature of refrigerant.

2011-01-01

203

An experimental study of frost formation on a horizontal cylinder under cross flow  

Energy Technology Data Exchange (ETDEWEB)

Frost layers formed on the front and rear surfaces of a horizontal cylinder during cross flow are found to be thicker than those at the top and bottom surfaces where the flow separation is nearly initiated. This observation was obtained in an experimental study carried out to examine frost formation on a horizontal cylinder given a cross flow condition. The thickness of the frost layer and the temperature distribution in the cylinder were measured for various experimental conditions. The local heat flux around the cylinder and the effective thermal conductivity of the frost layer were likewise evaluated, while thickness and surface temperature of the frost layer around the cylinder were measured periodically. These measurements were obtained by varying the Reynolds number, temperature, and humidity. The dew point temperature of the inlet air, however, was kept below the freezing point throughout the experiment. Results also reveal that inlet air velocity, temperature, and humidity affect thickness and thermal conductivity of the frost layer. (author)

Lee, Y.B. [Seoul National University (Korea). Institute of Advanced Machinery; Ro, S.T. [Seoul National University (Korea). School of Mechanical and Aerospace Engineering

2001-09-01

204

CONFLICT OVER BURIAL OF THE DEAD: ANALYSIS OF SOPHOCLES’ ANTIGONE AND ROBERT FROST’S “HOME BURIAL”  

Directory of Open Access Journals (Sweden)

Full Text Available We don’t always need giant issues, events, wars, national and international conflicts and catastrophes to reflect upon the culture, history and politics of a society at a given time and place. Routine and domestic issues are potentially possible to become terrific point of reference to debate and reflect larger concerns governing society and cultures. This essay analyzes how a routine, fundamental subject of burial of the dead creates conflicting discourses on relative position of law, religion and passions in different culture and how itleads to generate critical debate on women status, their efforts for identity, man-woman contrary response to death/burial and husband –wife relationship with reference to two literary texts of Sophocles’ Antigone and Frost’s “Home Burial”.

Asim Karim

2012-01-01

205

Effects of frost on wildflowers: an unexpected consequence of climate change--image 08 of 22  

Science.gov (United States)

Photo of a meadow with thousands of Helianthella quinquenervis (aspen sunflower, Asteraceae) plants. In the year that this photo was taken, a springtime frost killed all but a few flower buds. Compare with the photo of the same meadow in a year without frost. The lack of flowers in years having springtime frost has ecological consequences. There is no pollen or nectar for pollinators (bees and flies), no seeds for seed predators (tephritid flies and caterpillars), and no seed predators for parasitoid wasps.

Inouye, David

2012-01-04

206

Initial discussion on the damage propagation of rock under the frost and thaw condition  

Energy Technology Data Exchange (ETDEWEB)

Based on the experimental results obtained from CT scanning of rocks under the condition of frost-and-thaw cycle, the characteristics of damage propagation of three types of rock materials (sandstone, shale and coal) were studied under the conditions of frost-and-thaw cycles. The effect of the number of frost-and-thaw cycles on the damage propagation of rock is emphasised in the discussion. 6 refs., 4 figs., 4 tabs.

Yang, G.; Pu, Y. [Xian University of Science and Technology, Xian (China). Dept. of Civil Engineering

2002-08-01

207

Proteins Involved in Distinct Phases of Cold Hardening Process in Frost Resistant Winter Barley (Hordeum vulgare L.) cv Luxor  

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Full Text Available Winter barley is an economically important cereal crop grown in higher latitudes and altitudes where low temperatures represent an important environmental constraint limiting crop productivity. In this study changes in proteome of leaves and crowns in a frost tolerant winter barley cv. Luxor in relation to short and long term periods of cold followed by a brief frost treatment were studied in order to disclose proteins responsible for the cold hardening process in distinct plant tissues. The mentioned changes have been monitored using two dimensional difference gel electrophoresis (2D-DIGE) with subsequent peptide-mapping protein identification. Regarding approximately 600–700 distinct protein spots detected on 2D gels, there has been found at least a two-fold change after exposure to low temperatures in about 10% of proteins in leaves and 13% of proteins in crowns. Protein and nitrogen metabolic processes have been influenced by low temperature to a similar extent in both tissues while catabolism, carbohydrate metabolism and proteins involved in stress response have been more affected in crowns than in leaves. The range of changes in protein abundance was generally higher in leaves and chloroplast proteins were frequently affected which suggests a priority to protect photosynthetic apparatus. Overall, our data proved existence of slightly different response strategies to low temperature stress in crowns and leaves, i.e., tissues with different biological role. Moreover, there have been found several proteins with large increase in accumulation, e.g., 33 kDa oxygen evolving protein of photosystem II in leaves and “enhanced disease susceptibility 1” in crowns; these proteins might have potential to indicate an enhanced level of frost tolerance in barley.

Iva Hlavá?ková; Pavel Vítámvás; Ji?í Šantr??ek; Klára Kosová; Sylva Zelenková; Ilja Tom Prášil; Jaroslava Ovesná; Radovan Hynek; Milan Kodí?ek

2013-01-01

208

Proteins Involved in Distinct Phases of Cold Hardening Process in Frost Resistant Winter Barley (Hordeum vulgare L.) cv Luxor.  

UK PubMed Central (United Kingdom)

Winter barley is an economically important cereal crop grown in higher latitudes and altitudes where low temperatures represent an important environmental constraint limiting crop productivity. In this study changes in proteome of leaves and crowns in a frost tolerant winter barley cv. Luxor in relation to short and long term periods of cold followed by a brief frost treatment were studied in order to disclose proteins responsible for the cold hardening process in distinct plant tissues. The mentioned changes have been monitored using two dimensional difference gel electrophoresis (2D-DIGE) with subsequent peptide-mapping protein identification. Regarding approximately 600-700 distinct protein spots detected on 2D gels, there has been found at least a two-fold change after exposure to low temperatures in about 10% of proteins in leaves and 13% of proteins in crowns. Protein and nitrogen metabolic processes have been influenced by low temperature to a similar extent in both tissues while catabolism, carbohydrate metabolism and proteins involved in stress response have been more affected in crowns than in leaves. The range of changes in protein abundance was generally higher in leaves and chloroplast proteins were frequently affected which suggests a priority to protect photosynthetic apparatus. Overall, our data proved existence of slightly different response strategies to low temperature stress in crowns and leaves, i.e., tissues with different biological role. Moreover, there have been found several proteins with large increase in accumulation, e.g., 33 kDa oxygen evolving protein of photosystem II in leaves and "enhanced disease susceptibility 1" in crowns; these proteins might have potential to indicate an enhanced level of frost tolerance in barley.

Hlavá?ková I; Vítámvás P; Santr??ek J; Kosová K; Zelenková S; Prášil IT; Ovesná J; Hynek R; Kodí?ek M

2013-01-01

209

Effects of frost on wildflowers: an unexpected consequence of climate change--image 06 of 22  

Science.gov (United States)

Ants (Formica obscuripes) searching for extrafloral nectar on the involucral bracts around a flower head in bud in the frost-sensitive herb Helianthella quinquenervis. The ants help to deter oviposition by flies (Tephritidae) that try to lay eggs on the flower heads. Because fly larvae eat developing seeds, the ants benefit the plants. Thus, the ant / herb interaction represents a mutualism. This mutualism can be disrupted if flower buds are killed by frost, as they won't secrete the extrafloral nectar. But frost also negatively impacts the flies, as frost-killed buds provide no food for the fly larvae.

Inouye, David

2012-01-04

210

Fall frost resistance in willows used for biomass production. I. Characterization of seasonal and genetic variation.  

UK PubMed Central (United Kingdom)

Fast-growing willow clones (six clones of Salix viminalis L. and one clone each of S. viminalis x S. schwerenii E. Wolf and S. dasyclados Wimm.) were compared with respect to growth rhythm and frost hardening in the fall. Frost resistance of stem tissues was assessed by controlled freezing followed by analysis of chlorophyll fluorescence and scoring of visible cambial discoloration. The fluorescence method proved superior to scoring based on visible cambial discoloration because it was more rapid and less subjective, but needed calibration against cambial damage. Frost hardening in mature parts of stems did not start until growth cessation was initiated in the shoot apices, irrespective of whether growth cessation occurred early or late in the fall. Frost resistance varied because of clonal variations in: (1) pre-hardening frost resistance; (2) timing of growth cessation and hence start of frost hardening; and (3) rate of frost hardening. Compared with coastal and southern clones, continental and northern clones started hardening earlier, and a continental clone proceeded through hardening more rapidly at a given temperature. A cross between a continental and coastal clone was intermediate in timing. The pre-hardening frost resistance, however, was unrelated to both growth and frost hardening characteristics.

Ogren E

1999-09-01

211

Correlation for frost properties on a cold cylinder surface in cross flow  

Science.gov (United States)

An experimental study was reported earlier on the development of frost formation by humid flow passing over the cylinder. In this study, dimensionless correlations based on previous experimental data and reported empirical correlations of others for frost properties are proposed. The frost conduction coefficient is determined by using an analytical equation. Subsequently, correlations are sought for the heat conduction coefficient, dimensionless temperature, dimensionless thickness and density. The advantages of these correlations to any other proposed correlations are their explicit and dependency on time. Furthermore, an estimation of characteristics of the frost is followed by using the same approach and the established correlations.

Barzanoni, Y.; Basirat Tabrizi, H.; Noorshams, O.; Eftekhari, H.

2012-08-01

212

Modelling shallow landslide susceptibility by means of a subsurface flow path connectivity index and estimates of soil depth spatial distribution  

Science.gov (United States)

Topographic index-based hydrological models have gained wide use to describe the hydrological control on the triggering of rainfall-induced shallow landslides at the catchment scale. A common assumption in these models is that a spatially continuous water table occurs simultaneously across the catchment. However, during a rainfall event isolated patches of subsurface saturation form above an impeding layer and their hydrological connectivity is a necessary condition for lateral flow initiation at a point on the hillslope. Here, a new hydrological model is presented, which allows us to account for the concept of hydrological connectivity while keeping the simplicity of the topographic index approach. A dynamic topographic index is used to describe the transient lateral flow that is established at a hillslope element when the rainfall amount exceeds a threshold value allowing for (a) development of a perched water table above an impeding layer, and (b) hydrological connectivity between the hillslope element and its own upslope contributing area. A spatially variable soil depth is the main control of hydrological connectivity in the model. The hydrological model is coupled with the infinite slope stability model and with a scaling model for the rainfall frequency-duration relationship to determine the return period of the critical rainfall needed to cause instability on three catchments located in the Italian Alps, where a survey of soil depth spatial distribution is available. The model is compared with a quasi-dynamic model in which the dynamic nature of the hydrological connectivity is neglected. The results show a better performance of the new model in predicting observed shallow landslides, implying that soil depth spatial variability and connectivity bear a significant control on shallow landsliding.

Lanni, C.; Borga, M.; Rigon, R.; Tarolli, P.

2012-11-01

213

Frost characteristics and heat transfer on a flat plate under freezer operating conditions: Part 1, Experimentation and correlations  

Energy Technology Data Exchange (ETDEWEB)

An experimental investigation of frost growth on a flat, cold surface supplied by subfreezing, turbulent, humid, parallel flow of air is presented. The operating conditions are typical of many commercial freezers. A test loop was constructed to perform the tests, and the frost height, frost mass concentration, and cold surface heat flux were measured using specially designed and calibrated instrumentation. Twenty tests were done for steady operating conditions, each starting with no initial frost accumulation, and were run for two to six hours giving 480 data samples. Measured results show that the frost characteristics differ significantly with frost growth data taken previously for room temperature airflow. Depending on the temperature of the cold plate and the relative humidity of the subfreezing supply air, the frost could appear to be either smooth or rough. Smooth frost, which occurred at warmer plate temperatures and lower supply air relative humidities, gave rise to frost growth that was much thinner and denser than that for the rough, thick, low-density frost. Frost growth characteristics are correlated as a function of five independent variables (time, distance from the leading edge, cold plate temperature ratio, humidity ratio, and Reynolds number). These correlations are presented separately for the full data set, the rough frost data, and the smooth frost data.

Mao, Y.; Besant, R.W.; Chen, H.

1999-07-01

214

Frost formation on fin-and-tube heat exchangers. Pt. 1. Modeling of frost formation on fin-and-tube heat exchangers  

Energy Technology Data Exchange (ETDEWEB)

In this study, the heat and mass transfer characteristics of heat exchangers during frost formation process are analyzed numerically. Unsteady heat and mass transfer coefficients of the air side, heat transfer coefficient of the refrigerant side, air-frost layer interface temperature, the surface efficiency of the heat exchanger and the mass flow rate of the frost accumulated on the heat exchanger surface are calculated. The total conductivity (UA) and pressure drop of the heat exchanger are reported for different air inlet temperature, relative humidity, air mass flow rate and the refrigerant temperature. (author)

Seker, D.; Karatas, H. [Arcelik A.S., Istanbul (Turkey); Egrican, N. [Yeditepe University, Istanbul (Turkey)

2004-06-01

215

Soil  

International Nuclear Information System (INIS)

Environmental soil surveys in each province of Austria have been performed, soils of about 5,000 sites were described and analyzed for nutrients and pollutants, the majority of these data are recorded in the soil information system of Austria (BORIS) soil database, http://www.ubavie.gv.at/umweltsituation/boden/boris), which also contains a soil map of Austria, data from 30 specific investigations mainly in areas with industry and results from the Austria - wide cesium investigation. With respect to the environmental state of soils a short discussion is given, including two geographical charts, one showing which sites have soil data (2001) and the other the cadmium distribution in top soils according land use (forest, grassland, arable land, others). Information related to the soil erosion, Corine land cover (Europe-wide land cover database), evaluation of pollutants in soils (reference values of As, Cd, Co, Cr, Cu, Hg, Mo, Ni, Se, Pb, Tl, Va, Zn, AOX, PAH, PCB, PCDD/pcdf, dioxin), and relevant Austrian and European standards and regulations is provided. Figs. 2, Tables 4. (nevyjel)

2002-01-01

216

Vineyard frost protection with upward-blowing wind machines  

UK PubMed Central (United Kingdom)

Upward-blowing wind machines have been commercialized for use in frost protection but little quantitative information exists regarding how their operation alters site temperatures. In particular, their performance relative to conventional wind machines has been debated. To address this need, experiments were conducted on 12 spring frost nights in 2010 and 2011 in a commercial winegrape vineyard where either two upward-blowing wind machines or a single conventional wind machine were operated. Comprehensive measurements of air temperature changes caused by wind machine operation were evaluated on multiple transects at heights of 1.1, 4, 7 and 10m. All 12 frost nights were characterized by low wind and clear sky conditions, with temperature inversion strengths commonly associated with beneficial wind machine use occurring on 9 of the 12 nights. The operation of the conventional wind machine produced consistently larger and more statistically significant increases in temperature, particularly at the 1.1m vine level, as compared to the operation of the upward-blowing wind machines which produced very minor increases in temperature at the 1.1m level under strong inversion conditions and either no change or decreases in temperature under weaker inversion conditions. Based on the summary relationships between temperature changes as a function of inversion strength, under conditions of an inversion gradient of 0.2°Cm?1 the conventional wind machine would be expected to raise target area temperatures by 1.6°C at the vine level, while the upward-blowing wind machines would have no net effect under the same inversion conditions. Smoke tracking of the air flow from the upward-blowing wind machines indicated that the air jet reached 25m height, and then tended to slowly settle back towards the ground. These results indicate relatively poor performance of this type of low-powered (6.3kW) upward-blowing wind machine compared to a conventional wind machine under the conditions of this study.

Battany MC

2012-05-01

217

Soils  

International Nuclear Information System (INIS)

For Austria there exists a comprehensive soil data collection, integrated in a GIS (geographical information system). The content values of pollutants (cadmium, mercury, lead, copper, mercury, radio-cesium) are given in geographical charts and in tables by regions and by type of soil (forests, agriculture, greenland, others) for the whole area of Austria. Erosion effects are studied for the Austrian region. Legal regulations and measures for an effective soil protection, reduction of soil degradation and sustainable development in Austria and the European Union are discussed. (a.n.)

2001-01-01

218

Frost resistance of concrete with crushed brick as aggregate  

Directory of Open Access Journals (Sweden)

Full Text Available The investigation included concrete made by using recycled brick as aggregate. Experimental work included several types of concrete made with the same cement content (385 kg/m3), and same consistency (slump about 1 cm). Recycled brick and combination of natural river aggregate and recycled brick were used as aggregates. The influence of percentage and grain size of crushed brick aggregate on concrete compressive strength, water absorption and frost resistance were observed. On the basis of the results obtained during experimental research, a general conclusion can be drawn that the application of recycled concrete as aggregate can lead to new composites with satisfactory physical-mechanical properties.

Jankovi? Ksenija; Bojovi? Dragan; Nikoli? Dragan; Lon?ar Ljiljana; Romakov Zoran

2010-01-01

219

Nowcasting in the FROST-2014 Sochi Olympic project  

Science.gov (United States)

FROST (Forecast and Research: the Olympic Sochi Testbed) 2014 is a WMO WWRP international project aimed at development, implementation, and demonstration of capabilities of short-range numerical weather prediction and nowcasting technologies for mountainous terrain in winter season. Sharp weather contrasts and high spatial and temporal variability are typical for the region of the Sochi-2014 Olympics. Steep mountainous terrain and an intricate mixture of maritime sub-tropical and Alpine environments make weather forecasting in this region extremely challenging. Goals of the FROST-2014 project: • To develop a comprehensive information resource of Alpine winter weather observations; • To improve and exploit: o Nowcasting systems of high impact weather phenomena (precipitation type and intensity, snow levels, visibility, wind speed, direction and gusts) in complex terrain; o High-resolution deterministic and ensemble mesoscale forecasts in winter complex terrain environment; • To improve the understanding of physics of high impact weather phenomena in the region; • To deliver forecasts (Nowcasts) to Olympic weather forecasters and decision makers and assess benefits of forecast improvement. 46 Automatic Meteorological Stations (AMS) were installed in the Olympic region by Roshydromet, by owners of sport venues and by the Megafon corporation, provider of mobile communication services. The time resolution of AMS observations does not exceed 10 minutes. For a subset of the stations it is even equal to 1 min. Data flow from the new dual polarization Doppler weather radar WRM200 in Sochi was organized at the end of 2012. Temperature/humidity and wind profilers and two Micro Rain Radars (MRR) will supplement the network. Nowcasting potential of NWP models participating in the project (COSMO, GEM, WRF, AROME, HARMONIE) is to be assessed for direct and post-processed (e.g. Kalman filter, 1-D model, MOS) model forecasts. Besides the meso-scale models, the specialized nowcasting systems are expected to be used in the project - ABOM, CARDS, INCA, INTW, STEPS, MeteoExpert. FROST-2014 is intended as an 'end-to-end' project. Its products will be used by local forecasters for meteorological support of the Olympics and preceding test sport events. The project is open for new interested participants. Additional information is available at http://frost2014.meteoinfo.ru.

Bica, Benedikt; Wang, Yong; Joe, Paul; Isaac, George; Kiktev, Dmitry; Bocharnikov, Nikolai

2013-04-01

220

Theoretical and experimental studies of frost between two plates. Teoretiska och experimentella studier av frostbildning i luftspalt  

Energy Technology Data Exchange (ETDEWEB)

Frost has a complex structure and frost formation is influenced by several parameters, according to a literature study. A basic understanding of the frost formation process would be valuable in many situations, e.g. when optimizing equipment. A mathematical model for frost growth in a humid air stream between two plates, where one is cold, has been developed, based on mass balance, heat balance, and diffusion of water vapor in the frost. At the calculations, the space between the two plates is divided into a number of equally long elements. For each element, the balance equations and the equation for the diffusion of water vapor in the frost are formed. A new description is introduced by using a variable which denotes the part of the mass flux that is increasing the frost thickness. A computer program was developed, that with the use of experimental values from the literature, calculates the frost thickness, the frost density, the temperature of the frost surface, the mass flux to the frost layer, and the mass transfer coefficient. The results show good agreement between the values obtained from the model and the values obtained in experiments. An experimental facility has been built to investigate the frost growth between two cold plates, under conditions similar to those in an air to air heat exchanger. The frost thickness, the frost mass, the change in relative humidity with corresponding temperatures, the change in the temperature of the humid air and temperatures between the plates, can be measured. From these values, e.g. the heat flux, the mass flux, the heat transfer coefficient, the mass transfer coefficient, and the effective thermal conductivity of the frost can be calculated. The results of the experiments show how the frost formation depends on different parameters like time, the temperature of the cold surfaces, the inlet humidity, and the inlet air velocity.

Andersson, Ingrid.

1992-03-01

 
 
 
 
221

Theoretical and experimental studies of frost between two plates; Teoretiska och experimentella studier av frostbildning i luftspalt  

Energy Technology Data Exchange (ETDEWEB)

Frost has a complex structure and frost formation is influenced by several parameters, according to a literature study. A basic understanding of the frost formation process would be valuable in many situations, e.g. when optimizing equipment. A mathematical model for frost growth in a humid air stream between two plates, where one is cold, has been developed, based on mass balance, heat balance, and diffusion of water vapor in the frost. At the calculations, the space between the two plates is divided into a number of equally long elements. For each element, the balance equations and the equation for the diffusion of water vapor in the frost are formed. A new description is introduced by using a variable which denotes the part of the mass flux that is increasing the frost thickness. A computer program was developed, that with the use of experimental values from the literature, calculates the frost thickness, the frost density, the temperature of the frost surface, the mass flux to the frost layer, and the mass transfer coefficient. The results show good agreement between the values obtained from the model and the values obtained in experiments. An experimental facility has been built to investigate the frost growth between two cold plates, under conditions similar to those in an air to air heat exchanger. The frost thickness, the frost mass, the change in relative humidity with corresponding temperatures, the change in the temperature of the humid air and temperatures between the plates, can be measured. From these values, e.g. the heat flux, the mass flux, the heat transfer coefficient, the mass transfer coefficient, and the effective thermal conductivity of the frost can be calculated. The results of the experiments show how the frost formation depends on different parameters like time, the temperature of the cold surfaces, the inlet humidity, and the inlet air velocity.

Andersson, Ingrid

1992-03-01

222

Predicting Frost Resistance of Concrete with Different Coarse Aggregate Concentration by Porosity Parameters  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Frost resistance is one of the key indicators of concrete quality. Frost resistance can be determined by direct testing; however it is time-consuming and labour-intensive method. Concrete decomposition is a complex process (from initial signs of degradation to complete failure of the surface subject...

Džigita NAGROCKIEN?; Gintautas SKRIPKI?NAS; Giedrius GIRSKAS

223

Effects of frost on wildflowers: an unexpected consequence of climate change--image 04 of 22  

Science.gov (United States)

A graphical representation of a frost event at the Rocky Mountain Biological Laboratory (Colorado). The temperature dipped to 25.1 F on 11 June 2004. Winter snowpack melted at the monitoring location on 8 May that year. The late-spring frost killed flower buds that had developed in the four weeks following snowmelt.

Inouye, David

2012-01-04

224

A Novel Approach to Study the Performance of Finned-Tube Heat Exchangers under Frosting Conditions  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Frost accumulation due to moist air flowing on a refrigeration coil cold surface impacts negatively on performance. The frost layer growth has an insulating effect in terms of heat transfer and causes the increase of the air pressure drop by blocking the free flow area across the coil. In ...

A.L. Bendaoud; M. Ouzzane; Z. Aidoun; N. Galanis

225

Heat and mass transfer in frost and ice, packed beds, and environmental discharges  

International Nuclear Information System (INIS)

This volume covers issues related to heat and mass transfer in frost and ice packed beds, and environmental discharges. Topics include: measurements of the effects of frost on heat exchanger performance, a study of steam zone behavior in porous media, heat and mass transfer by natural convection, and a review of selected programs for atmospheric dispersion

1990-01-01

226

Frost damage of masonry walls - a hygrothermal analysis by computer simulations  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Frost damage occurs especially if damp building elements are subjected to frequent freeze-thaw cycles. The observation that frost damage can also be frequently observed in warmer winters - for example in the winter of 98/99 confirms that one cannot use the outside air temperature level as the only c...

Sedlbauer, K.; Künzel, H.M.

227

Mechanisms of salt frost scaling on portland cement-bound materials: studies and hypothesis  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A hypothesis regarding the mechanism causing salt frost scaling on Portland cement-bound materials is described. It is assumed that deterioration is due to osmotic micro ice body growth, as has been previously proposed for frost deterioration of moisture-isolated specimens of cement-bound materials....

Lindmark, Sture

228

David Sanders. A Divided Poet: Robert Frost, North of Boston, and the Drama of Disappearance.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

David Sanders in his monograph entitled A Divided Poet: Robert Frost, North of Boston, and the Drama of Disappearance (2011) sheds light on the dilemmas, doubts and personal conflicts Frost confronted while composing his poetic collection North of Boston in which some of his most well-known lyrics, ...

Tatiani G. Rapatzikou

229

Effective Thermal Conductivity of Frost Considering Mass Diffusion and Eddy Convection.  

Science.gov (United States)

A physical model for the effective thermal conductivity of water frost is proposed for application to the full range of frost density. The proposed model builds on the Zehner-Schlunder one-dimensional formulation for porous media appropriate for solid-to-...

M. Kandula

2010-01-01

230

Impact of abiotic factors on frost resistance and cold acclimation in Salix species and clones  

Energy Technology Data Exchange (ETDEWEB)

The effects of mineral nitrogen, photoperiod and day-night temperature on frost resistance and growth cessation in Salix species and clones are discussed. Increased nitrogen supply and imbalances between nitrogen and other elements might cause extensive frost damage in plants of Salix. Vegetation frosts below -3 deg C reduces the level of annual yield. Although Salix clones differ in resistance to freezing stress, the capacity to recover and grow after frosts are equal essential properties which affect the growth and biomass production of shoots after night frosts in June. Early autumn frosts causing freezing damage not only may delay the onset of growth cessation and cold acclimation, but also affect the winter survival of shoots. Increased nitrogen supply prior to cold acclimation postponed growth cessation and cold acclimation. Differences in nutrient status in plants cause also differences in retranslocation of mineral nutrients. Absence of damaging autumn frosts allow plants irrespective of nitrogen status to develop a frost resistance of at least - 80 deg C. 21 refs, 1 fig, 3 tabs

Fircks, H. von [Swedish Univ. of Agricultural Sciences, Uppsala (Sweden). Dept. of Short Rotation Forestry

1996-12-31

231

Frost as a first wall for the ICF Laboratory Microfusion Facility  

Energy Technology Data Exchange (ETDEWEB)

We introduce the concept of using frost as the first wall of the ICF Laboratory Microfusion Facility being designed to produce 200--1000 MJ of thermonuclear yield. We present one design incorporating 2 cm of frost deposited at 0.1 g/cm/sup 3/ on an LN-cooled fiber-reinforced polymer substrate. We calculate that such a frost layer will protect the substrate from ablation by target x rays and debris, and from shock-induced spallation. Postshot washdown with water should permit low-activation operation, and should preserve the original wall properties. We expect the impact of the frost on laser optics to be minimal, and expect the preshot lifetime of thermally unprotected cryogenic targets to be extended by operating the wall at 100-150 K. Moreover, we believe that such a frost first wall will involve little technical risk, and will be inexpensive to construct and operate. 4 refs., 1 fig.

Orth, C.D.

1988-11-15

232

Frost as a first wall for the ICF Laboratory Microfusion Facility  

International Nuclear Information System (INIS)

We introduce the concept of using frost as the first wall of the ICF Laboratory Microfusion Facility being designed to produce 200--1000 MJ of thermonuclear yield. We present one design incorporating 2 cm of frost deposited at 0.1 g/cm3 on an LN-cooled fiber-reinforced polymer substrate. We calculate that such a frost layer will protect the substrate from ablation by target x rays and debris, and from shock-induced spallation. Postshot washdown with water should permit low-activation operation, and should preserve the original wall properties. We expect the impact of the frost on laser optics to be minimal, and expect the preshot lifetime of thermally unprotected cryogenic targets to be extended by operating the wall at 100-150 K. Moreover, we believe that such a frost first wall will involve little technical risk, and will be inexpensive to construct and operate. 4 refs., 1 fig

1988-01-01

233

Frost as a first wall for the ICF laboratory microfusion facility  

International Nuclear Information System (INIS)

The authors introduce the concept of using frost as the first wall of the ICF Laboratory Microfusion Facility being designed to produce 200-1000 MJ of thermonuclear yield. They present one design incorporating 2cm of frost deposited at 0.1 g/cm/sup 3/ on an LN-cooled fiber-reinforced polymer substrate. They calculate that such a frost layer will protect the substrate from ablation by target x rays and debris, and from shock-induced spallation. Postshot washdown with water should permit low-activation operation, and should preserve the original wall properties. The authors expect the impact of the frost on laser optics to be minimal, and expect the preshot lifetime of thermally unprotected cryogenic targets to be extended by operating the wall at 100-150 K. Moreover, they believe that such a frost first wall involves little technical risk, and will be inexpensive to construct and operate

1989-01-01

234

The theoretical Model for predicting the behaviors of the frost formation  

Energy Technology Data Exchange (ETDEWEB)

A theoretical model of the frost formation has been presented to investigate the characteristics of the growth of frost layer by considering molecular diffusion of water vapor and heat generation caused by sublimation of water vapor in the frost layer. The present model was compared with existing experimental data as well as a previous model. The difference between the present model and existing experimental data was found to be about 6 percent. An analysis for the behavior of frost formation using present model shows a good agreement with the trend for a number of experimentally observed features. The present analysis can also provide the physical understanding on the phenomena of the frost formation. (author). 18 refs., 14 figs., 1 tab.

Lee, K.S. [Hanyang University, Seoul (Korea, Republic of); Lee, T.H.; Heo, J.H. [Hanyang University Graduate School, Seoul (Korea, Republic of)

1996-03-01

235

Field tests on protection methods against frost actions using gravel and permeable thermal insulating material. Jari oyobi tosuisei dannetsuzai wo mochiiru shasuiso no tojo yokusei koka  

Energy Technology Data Exchange (ETDEWEB)

As a measure to prevent ground frosting in cold regions, an experiment has been performed on frost suppressing effect of a filter bed that lets seepage water from above such as rain water pass and shuts off rise of capillary water from below. This paper summarizes the result of the experiment. The experiment has used frosty soil (weathered volcanic ash), gravel as a filter bed, and permeable thermal insulating material (block obtained from fusion of styrene foam). A ground that has not been given a filtering construction has continued with ground surface upheaval until the end of March with the upheaval having reached as high as 17 cm or more. With a ground given a filtering construction, the frost amount has increased little after the middle of December, 6 cm in the case of using the insulating material and 9 cm using the gravel up to March. Water freezes faster in the ground given the water filtering construction because of less latent heat generated from the water and action of heat insulating effect of the filtering bed. A comparison of water content after freezing has indicated that the ground not given the construction increases the water content, but the ground given the construction shows little change, thus verifying the filtering effect. The ground given the construction using the heat insulating material reduces the maximum freezing depth because of its heat insulating effect. 8 refs., 7 figs., 2 tabs.

Liu, C.; Suzuki, T.; Sawada, M. (Kitami Institute of Technology, Hokkaido (Japan))

1994-03-21

236

Relationship between Ice Nucleation Frequency of Bacteria and Frost Injury.  

UK PubMed Central (United Kingdom)

Not every cell of a given bacterial isolate that has ice-nucleating properties can serve as an ice nucleus at any given time and temperature. The ratio between the number of ice nuclei and number of bacterial cells in a culture (i.e. nucleation frequency) was found to vary with incubation temperature, growth medium composition, culture age, and genotype. Optimal conditions for ice nucleus production in vitro included incubation of the bacterial cells at 20 to 24 degrees C on nutrient agar containing glycerol. The relationship between nucleation frequency and frost injury was examined by subjecting corn seedlings to -4 degrees C immediately after they were sprayed with bacterial suspensions with different nucleation frequencies and by following both ice nucleus concentration and bacterial population size on leaves of corn seedlings as a function of time after bacterial application. The amount of frost injury to growth chamber-grown corn seedlings at -4 degrees C was a function of the number of ice nuclei active at that temperature on the leaves. The number of ice nuclei, in turn, is the product of the nucleation frequency and population size of ice-nucleation-active bacteria present on the leaves.

Lindow SE; Hirano SS; Barchet WR; Arny DC; Upper CD

1982-10-01

237

Genetic effects in callose content in root apex of inbred resistant and susceptible corn lines to acid soils Efectos genéticos de la formación de calosa en ápices radicales de líneas de maíz resistentes y susceptibles a suelos ácidos  

Directory of Open Access Journals (Sweden)

Full Text Available The main objective of this work was to identify genetic parameters that are related to callose accumulation using tropical inbreeds corn. Fourteen inbreed lines selected for different levels of tolerance to acid soils were chosen and a diallel among them was generated. The seeds were grown under controlled environmental conditions in a growth chamber and transferred to a nutrient solution at pH 4.3. After 12 hours of 25 µM Al (AlCl3) treatment was applied, callose contents of 1 cm root apex were determined with fluorescence spectrophotometer. Significant differences were found for parents, crosses and parents vs crosses. Average callose content varied from 0.746 to 2.035 (µg PE/cm root apex). Heterosis varied from –21.2% to 276.3%. General combining ability (GCA) and specific combining ability (SCA) were highly significant indicating that both, additive and non–additive gene effects were important for callose inheritance. SCA and GCA sum of squares accounted for 54% and 46%, respectively of crosses of squares sum. Correlation coefficient between callose content and corn grain yield in the field was negative but not significant (r = –0.38).Key words: Zea mays; callose; inheritance; diallel; heterosis; acid soils.El objetivo de este trabajo fue estudiar la herencia de la producción de calosa utilizando líneas endogámicas de maíz. Seleccionando 14 líneas (7 tolerantes y 7 susceptibles a suelos ácidos) se formó un dialelo que fue probado en campo y en invernadero. Se determinó el contenido de calosa en los 91 cruzamientos resultantes y los 14 progenitores. Para ello se colocaron las semillas en cámara de crecimiento en condiciones controladas. Después de 4–5 días las plántulas fueron transferidas a cubetas que contenían solución nutritiva con aireación constante. Luego de 48 horas se adicionaron 25 µM de aluminio (AlCl3) a cada una de las cubetas y se mantuvieron por 12 horas. Se cortaron tres ápices radicales de cada genotipo y se mantuvieron en etanol 96%. Para medir el contenido de calosa se utilizó Methyl blue como colorante, este forma un complejo con la calosa llamado Siruflúor–calosa, que es medido con el espectrofotómetro de fluorescencia. Se encontraron diferencias significativas para los progenitores, los cruzamientos y los progenitores Vs cruzamientos. El contenido de calosa de los progenitores varió de 0.746 a 2.035 µg PE/cm ápice de raíz. La heterosis varió desde –21.2% a 276.3%. La Habilidad Combinatoria General (HCG) y la Habilidad Combinatoria Específica (HCE) fueron altamente significativas, lo que indica que tanto los efectos genéticos aditivos y no aditivos fueron importantes en la herencia de calosa. El 46% de SC entre cruzamientos correspondió a la HCG y el 54% a la HCE. El coeficiente de correlación entre el contenido de calosa y la producción de grano del maíz en el campo fue negativo aunque no significativo (r = –0.38).Palabras claves: Zea mays; calosa; heredabilidad; dialelo; heterosis; suelos ácidos.

Arcos Alba Lucía; Narro Luis Alberto; Salazar Fredy Alberto; Caetano Creuci Maria

2007-01-01

238

Simulating transmission and control of Taenia solium infections using a reed-frost stochastic model  

DEFF Research Database (Denmark)

The transmission dynamics of the human-pig zoonotic cestode Taenia solium are explored with both deterministic and stochastic versions of a modified Reed-Frost model. This model, originally developed for microparasitic infections (i.e. bacteria, viruses and protozoa), assumes that random contacts occur between hosts and that hosts can be either susceptible, infected or ‘recovered and presumed immune'. Transmission between humans and pigs is modelled as susceptible roaming pigs scavenging on human faeces infected with T. solium eggs. Transmission from pigs to humans is modelled as susceptible humans eating under-cooked pork meat harbouring T. solium metacestodes. Deterministic models of each scenario were first run, followed by stochastic versions of the models to assess the likelihood of infection elimination in the small population modelled. The effects of three groups of interventions were investigated using the model: (i) interventions affecting the transmission parameters such as use of latrines, meat inspection, and cooking habits; (ii) routine interventions including rapid detection and treatment of human carriers or pig vaccination; and (iii) treatment interventions of either humans or pigs. It is concluded that mass-treatment can result in a short term dramatic reduction in prevalence, whereas interventions targeting interruption of the life cycle lead to long-term reduction in prevalence.

Kyvsgaard, Niels Chr.; Johansen, Maria Vang

2007-01-01

239

Measurement of frost characteristics on heat exchanger fins. Part 1: Test facility and instrumentation  

Energy Technology Data Exchange (ETDEWEB)

A special test facility was developed to characterize frost growing on heat exchanger fins where the cold surfaces and the air supply conditions were similar to those experienced in freezers, i.e., cold surface temperatures ranging from {minus}35 C to {minus}40 C, air supply temperatures from {minus}10 C to {minus}20 C, and 80% to 100% relative humidity (RH). This test facility included a test section with removable fins to measure the frost height and mass concentration. Frost height on heat exchanger fins was measured using a new automated laser scanning system to measure the height of frost and its distribution on selected fins. The increase in air pressure loss resulting from frost growth on the fins was measured directly in the test loop. The frost mass accumulation distribution was measured for each test using special pre-etched fins that could be easily subdivided and weighed. The total heat rate was measured using a heat flux meter. These frost-measuring instruments were calibrated and the uncertainty of each is stated.

Thomas, L.; Chen, H.; Besant, R.W.

1999-07-01

240

Modeling the airside dynamic behavior of a heat exchanger under frosting conditions  

International Nuclear Information System (INIS)

A general distributed model with a non-steady-state heat exchanger model coupled with a frost model was developed to study the dynamic behavior of an airside heat exchanger in an air-to-water heat pump heater/chiller unit. The effects of water vapor diffusion and uneven fin temperature distribution were considered. The model was found to agree well with reported experimental results. Compared with the routine model, the present model has higher precision of frost layer thickness especially on the fin surface. Results include the propagation of frost formation along the tube and its effect on the dynamic characteristics of refrigerant, air, and tube sides. According to the results, the temperature difference between air and tube surface temperature was proposed to be the main driving force of frosting. Tube surface temperature is the most important factor affecting frosting when there is little variation in air humidity. Frost at the fin base was found to be thicker than that at the fin tip due to the fact that the frost layer grows faster with lower tube surface temperature

2011-01-01

 
 
 
 
241

Helicity Asymmetry in gamma p -> pi+ n with FROST  

International Nuclear Information System (INIS)

The main objective of the FROST experiment at Jefferson Lab is the study of baryon resonances. The polarization observable E for the reaction gamma p to pi+n has been measured as part of this program. A circularly polarized tagged photon beam with energies from 0.35 to 2.35 GeV was incident on a longitudinally polarized frozen-spin butanol target. The final-state pions were detected with the CEBAF Large Acceptance Spectrometer. Preliminary polarization data agree fairly well with present SAID and MAID partial-wave analyses at low photon energies. In most of the covered energy range, however, significant deviations are observed. These discrepancies underline the crucial importance of polarization observables to further constrain these analyses.

2012-01-01

242

Helicity Asymmetry in gamma p -> pi+ n with FROST  

CERN Document Server

The main objective of the FROST experiment at Jefferson Lab is the study of baryon resonances. The polarization observable E for the reaction gamma p to pi+n has been measured as part of this program. A circularly polarized tagged photon beam with energies from 0.35 to 2.35 GeV was incident on a longitudinally polarized frozen-spin butanol target. The final-state pions were detected with the CEBAF Large Acceptance Spectrometer. Preliminary polarization data agree fairly well with present SAID and MAID partial-wave analyses at low photon energies. In most of the covered energy range, however, significant deviations are observed. These discrepancies underline the crucial importance of polarization observables to further constrain these analyses.

Strauch, Steffen

2011-01-01

243

Frost resistance of ceramic floor tiles : a prenormative study  

Energy Technology Data Exchange (ETDEWEB)

In this work, the mechanisms of floor damaging are studied on the basis of physical characteristics, mechanical fatigue tests and Finite Element calculation. It has been demonstrated that the volume expansion associated with ice formation, even if deleterious at a micronic scale, is not able alone to induce the characteristic flaws observed outdoor. Therefore, additional stresses associated with laying are very likely involved in the damaging mechanism. Such stresses (compressive or tensile according to the season) are mainly due to: (1) the thermal mismatch between the tile and the basement. (2) the impediment of any free expansion due to the surrounding construction The major role of those macroscopic stresses and their related effect has been highlighted both by mechanical fatigue tests (static and cyclic loading) and by frost-thawing cycles performed on tiles embedded into a stiff concrete structure. According to those tests, outdoor flaws have been effectively reproduced in laboratory. (orig.)

Descamps, P.; Tirlocq, J.; Andre, S.; Deletter, M.; Cambier, F. [Belgian Ceramic Research Centre (BCRC) (Belgium); Barquin, F. de; Claes, S. [CSTC, LIMELETTE (Belgium)

2002-07-01

244

CFD analysis of tube-fin 'no-frost' evaporators  

Directory of Open Access Journals (Sweden)

Full Text Available The purpose of this paper is to assess some aspects of the design of evaporators for household refrigeration appliances using Computational Fluid Dynamics (CFD). The evaporators under study are tube-fin 'no-frost' heat exchangers with forced convection on the air-side and a staggered tube configuration. The calculation methodology was verified against experimental data for the heat transfer rate, thermal conductance and pressure drop obtained for two evaporators with different geometries. The average errors of the heat transfer rate, thermal conductance and pressure drop were 10%, 3% and 11%, respectively. The CFD model was then used to assess the influence of geometric parameters such as the presence and position of the electrical heater coil relative to the tubes, the fin configuration and the width of the by-pass clearance between the outer edge of the fins and the tube bank for conditions typical of the design of household refrigeration appliances

Jader R Barbosa, Jr; Christian J. L Hermes; Cláudio Melo

2010-01-01

245

CFD analysis of tube-fin 'no-frost' evaporators  

Scientific Electronic Library Online (English)

Full Text Available Abstract in english The purpose of this paper is to assess some aspects of the design of evaporators for household refrigeration appliances using Computational Fluid Dynamics (CFD). The evaporators under study are tube-fin 'no-frost' heat exchangers with forced convection on the air-side and a staggered tube configuration. The calculation methodology was verified against experimental data for the heat transfer rate, thermal conductance and pressure drop obtained for two evaporators with diff (more) erent geometries. The average errors of the heat transfer rate, thermal conductance and pressure drop were 10%, 3% and 11%, respectively. The CFD model was then used to assess the influence of geometric parameters such as the presence and position of the electrical heater coil relative to the tubes, the fin configuration and the width of the by-pass clearance between the outer edge of the fins and the tube bank for conditions typical of the design of household refrigeration appliances

Barbosa, Jr, Jader R; Hermes, Christian J. L; Melo, Cláudio

2010-12-01

246

The frost peat production; Routapalaturpeen tuotantoketjun tekniikka, talous ja ympaeristoevaikutukset  

Energy Technology Data Exchange (ETDEWEB)

The frost peat production means the cutting of frozen peat in the winter time. The aim of this study is to test the possibilities to prolong the peat production season and to produce peat pieces for the horticultural peat industry. The tests of the production were carried out in Vihanti municipality in the Northern Ostrobothnia region during winters 1996 and 1997. In the frost peat production method the frozen peat field is sawn throughout the lengthwise and crosswise of the bog by a circle saw. The sawn peat blocks are loosened from the field by a block-lifter. The circle saw is equipped with the five circle saw blades (diameter 90 cm). The distance of the blades is adjustable. The block-lifter is equipped with a horizontal position blade (width 35 cm). The dimensions of the peat block are changeable, but from the point of drying the upper limit of the side of the peat cube is 15-20 cm. The frost peat production method is technically suitable for the production of slightly decomposed (H1-5) energy and horticultural peat. The horticultural peat blocks must be transferred to the separate drying field, because on the cutting field the amount of the peat (about 1500-2000 m{sup 3}/ha) is far too much for drying. The peat blocks are spread out on the drying field by the self-unloading wagon. The well drained cutover fields are applicable as the drying fields. The energy peat blocks are allowed to dry up 70-75 % moisture content on the cutting field and then the blocks can be ridged by the screening ridger. If necessary, the ridges can be turned over. In the frost peat production, the conventional sod peat winning machines can be used in the following stages of the working tasks: harrowing, ridging, loading, turning of ridges and stockpiling. The amount of the test production in the winter 1996 was about 5500 m{sup 3} and in the winter 1997 about 1150 m{sup 3} (wet volume). The peat blocks were cut in February and in March. The horticultural peat pieces were spread out on the drying field having a density 550-800 m{sup 3}/ha. In the year 1996 the weather conditions for peat drying in May and in June were not good. Not until in July, there was a sufficiently long rainless period. The horticultural peat was harvested in 25th of July. The energy peat was left for drying on the ridges and was harvested three weeks later. In the year 1997 the horticultural peat was harvested in two parts; the first one in 14th of June and the rest in 22th of July. The complete drying process of the peat blocks requires about two weeks with less than 10 millimetres of precipitation. The measured output of the circle saw was about 45-50 m{sup 3}/h of energy peat and 55-60 m{sup 3}/h of horticultural peat. The output of the block-lifter was 120-160 m{sup 3}/h. Theoretically, the output of circle saw and the block-lifter can easily be doubled. Thereafter the production costs will be about 19 Fmk/MWh of energy peat and 18,6 Fmk/m{sup 3} of horticultural peat. (orig.)

Nyroenen, T. [Vapo Oy, Jyvaeskylae (Finland); Leiviskae, V. [Oulu Univ., Thule Institute (Finland)

1998-12-31

247

Correlations of frost properties considering the environmental parameters over a cold flat plate  

Energy Technology Data Exchange (ETDEWEB)

This study has been performed experimentally to measure the frost properties over a cold flat plate in order to obtain the correlations of the frost properties with various environmental parameters. Correlations of the frost surface temperature, thickness, density, and thermal conductivity are presented along with the experimental results as a function of environmental parameters, distance from the leading edge of test plate, and time. These correlations can be used to predict the frost properties with a maximum error of 8% in the following ranges : air temperature 15 {approx} 25 deg.C, relative humidity 60 {approx} 80%, air velocity 1 {approx} 3 m/s and cooling plate temperature -15 {approx} -25 deg.C.. (author). 12 refs., 6 figs., 2 tabs.

Lee, K.S. [Hanyang University, Seoul (Korea); Kim, Y.C.; Jhee, S. [Hanyang University Graduate School, Seoul (Korea)

2001-08-01

248

Effects of frost on wildflowers: an unexpected consequence of climate change--image 18 of 22  

Science.gov (United States)

A queen bumble bee (Bombus bifarius) foraging for nectar on a flower of Erythronium grandiflorum (glacier lily). This flower has frost-sensitive ovaries. Bumble bee queens and hummingbirds are common pollinators of Erythronium grandiflorum flowers.

Inouye, David

2012-01-04

249

Effects of frost on wildflowers: an unexpected consequence of climate change--image 19 of 22  

Science.gov (United States)

Example of a frost-killed ovary (on left) and a normally developing fruit (on right) of Erythonium grandiflorum, the glacier lily. The two plants were selected to show the difference, and weren't growing next to each other.

Inouye, David

2012-01-04

250

Effects of frost on wildflowers: an unexpected consequence of climate change--image 16 of 22  

Science.gov (United States)

Buds of Delphinium barbeyi (tall larkspur, Ranunculaceae) killed by a late season frost. In those years, the larkspur suffers reproductive failure, affecting animal species that rely on them for food.

Inouye, David

2012-01-04

251

Effects of frost on wildflowers: an unexpected consequence of climate change--image 13 of 22  

Science.gov (United States)

Delphinium barbeyi, or tall larkspur, flowering in a year with no frost damage. Photographed (by David Inouye) in front of Gothic Mountain, at the Rocky Mountain Biological Laboratory. Altitude about 9,500 ft (2,900m).

Inouye, David

2012-01-04

252

Siim Nestor soovitab : Ben Frost ja Alexander Robotnik Eclectical / Siim Nestor  

Index Scriptorium Estoniae

Austraalia muusik ja helilooja Ben Frost projektiga "6 guitars" esinemas festivali Eclectica raames 6. sept. Tartu klubis Rock ja Roll ja itaalia diskor Alexander Robotnik 7. sept. klubis Trehv, esinejatest

Nestor, Siim, 1974-

2007-01-01

253

Alleviation of frost damage to corn by controlling INA bacteria with competitive bacteria and chemicals  

UK PubMed Central (United Kingdom)

In this study, one kind of competitive bacteria and several chemical were tested for their efficacy in alleviating frost damage to corn by controlling ice nucleation active (INA) bacteria inhabiting on adult plants.. When frost occurred at -4?, all the three kinds of treatments showed effective in reducing frost damage to corn, with an efficacy order of Fangshuangji No.1 (54.94%), Kangshuangsu plus competitive bacterium of SR01006 (33.63%), Kangshuangsu plus Zhuangfengyou (22.35%). Fangshuangji No.1 was most effective, which both eradicate INA bacteria and destroy ice mucleating protein. As a new type of bactericide, it is safe to environment and has a broad anti-bacterial spectrum. Considering its good performance in controlling frost damage, Fangshuangji No.1 is worthy to be further studied.

Sun Fuzai; Zhao Tingchang; Mou Fengsheng; An Jianyong; Guo Shang; Sun Zhen; Sun Zhongfu

2003-01-01

254

Efectos genéticos de la formación de calosa en ápices radicales de líneas de maíz resistentes y susceptibles a suelos ácidos Genetic effects in callose content in root apex of inbred resistant and susceptible corn lines to acid soils  

Directory of Open Access Journals (Sweden)

Full Text Available El objetivo de este trabajo fue estudiar la herencia de la producción de calosa utilizando líneas endogámicas de maíz. Seleccionando 14 líneas (7 tolerantes y 7 susceptibles a suelos ácidos) se formó un dialelo que fue probado en campo y en invernadero. Se determinó el contenido de calosa en los 91 cruzamientos resultantes y los 14 progenitores. Para ello se colocaron las semillas en cámara de crecimiento en condiciones controladas. Después de 4-5 días las plántulas fueron transferidas a cubetas que contenían solución nutritiva con aireación constante. Luego de 48 horas se adicionaron 25 µM de aluminio (AlCl3) a cada una de las cubetas y se mantuvieron por 12 horas. Se cortaron tres ápices radicales de cada genotipo y se mantuvieron en etanol 96%. Para medir el contenido de calosa se utilizó Methyl blue como colorante, este forma un complejo con la calosa llamado Siruflúor-calosa, que es medido con el espectrofotómetro de fluorescencia. Se encontraron diferencias significativas para los progenitores, los cruzamientos y los progenitores Vs cruzamientos. El contenido de calosa de los progenitores varió de 0.746 a 2.035 µg PE/cm ápice de raíz. La heterosis varió desde -21.2% a 276.3%. La Habilidad Combinatoria General (HCG) y la Habilidad Combinatoria Específica (HCE) fueron altamente significativas, lo que indica que tanto los efectos genéticos aditivos y no aditivos fueron importantes en la herencia de calosa. El 46% de SC entre cruzamientos correspondió a la HCG y el 54% a la HCE. El coeficiente de correlación entre el contenido de calosa y la producción de grano del maíz en el campo fue negativo aunque no significativo (r = -0.38).The main objective of this work was to identify genetic parameters that are related to callose accumulation using tropical inbreeds corn. Fourteen inbreed lines selected for different levels of tolerance to acid soils were chosen and a diallel among them was generated. The seeds were grown under controlled environmental conditions in a growth chamber and transferred to a nutrient solution at pH 4.3. After 12 hours of 25 µM Al (AlCl3) treatment was applied, callose contents of 1 cm root apex were determined with fluorescence spectrophotometer. Significant differences were found for parents, crosses and parents vs crosses. Average callose content varied from 0.746 to 2.035 (µg PE/cm root apex). Heterosis varied from -21.2% to 276.3%. General combining ability (GCA) and specific combining ability (SCA) were highly significant indicating that both, additive and non-additive gene effects were important for callose inheritance. SCA and GCA sum of squares accounted for 54% and 46%, respectively of crosses of squares sum. Correlation coefficient between callose content and corn grain yield in the field was negative but not significant (r = -0.38).

Alba Lucía Arcos; Luis Alberto Narro; Fredy Salazar; Creuci Caetano

2007-01-01

255

Effects of frost on wildflowers: an unexpected consequence of climate change--image 07 of 22  

Science.gov (United States)

A meadow with thousands of plants of Helianthella quinquenervis (aspen sunflower, Asteraceae) at peak bloom. This species is a common long-lived perennial plant in meadows near the Rocky Mountain Biological Laboratory. This photo was taken during a year without frost damage. Compare the presence and density of sunflowers with the photograph of the same meadow in a year when frost damage killed all but a few flower buds.

Inouye, David

2012-01-04

256

Ensemble analysis of frost damage on vegetation caused by spring backlashes in a warmer Europe  

Directory of Open Access Journals (Sweden)

Full Text Available Tree dehardening and budburst will occur earlier in a warmer climate, and this could lead to an increased risk of frost damage caused by temperature backlashes. By using a spring backlash index and a cold hardiness model, we assessed different aspects of risk for frost damage in Norway spruce forests during the present climate and for one future emission scenario. Uncertainties associated with climate modelling were quantified by using temperature data from three climate data sets: (1) E-Obs gridded observed climate data, (2) an ensemble of data from eight regional climate models (RCM) forced by ERA-40 reanalysis data, (3) an ensemble of regional climate scenarios produced by the regional climate model RCA3 driven at the boundary conditions by seven global climate models (GCM), all representing the SRES A1B emission scenario. The frost risk was analysed for three periods, 1961–1990, 2011–2040 and 2070–2097. The RCA3_GCM ensemble indicated that the risk for spring frost damage may increase in the boreo-nemoral forest zone of southern Scandinavia and the Baltic states/Belarus. This is due to an increased frequency of backlashes, lower freezing temperatures after the onset of the vegetation period and the last spring frost occurring when the trees are closer to budburst. The changes could be transient due to the fine balance between an increased risk of frost damage caused by dehardening during a period when freezing temperatures are common and a decreased risk caused by warmer temperatures. In the nemoral zone, the zone with highest risk for spring backlashes during the reference period (1961–1990), the spring frost severity may increase due to frost events occurring when the trees are closer to budburst. However, the risk in terms of frequency of backlashes and freezing temperature were projected to become lower already in the beginning of this century.

A. M. Jönsson; L. Bärring

2011-01-01

257

Reconstructing patterns of temperature, phenology, and frost damage over 124 years: spring damage risk is increasing.  

UK PubMed Central (United Kingdom)

Climate change, with both warmer spring temperatures and greater temperature fluctuations, has altered phenologies, possibly leading to greater risk of spring frost damage to temperate deciduous woody plants. Phenological observations of 20 woody species from 1993 to 2012 in Trelease Woods, Champaign County, Illinois, USA, were used to identify years with frost damage to vegetative and reproductive phases. Local temperature records were used in combination with the phenological observations to determine what combinations of the two were associated with damage. Finally, a long-term temperature record (1889-1992) was evaluated to determine if the frequency of frost damage has risen in recent decades. Frost < or = -1.7 degrees C occurred after bud-break in 14 of the 20 years of observation. Frost damage occurred in five years in the interior and in three additional years at only the forest edge. The degree of damage varied with species, life stage, tissue (vegetative or reproductive), and phenological phase. Common features associated with the occurrence of damage to interior plants were (1) a period of unusual warm temperatures in March, followed by (2) a frost event in April with a minimum temperature < or = -6.1 degrees C with (3) a period of 16-33 days between the extremes. In the long-term record, 10 of 124 years met these conditions, but the yearly probability of frost damage increased significantly, from 0.03 during 1889-1979 to 0.21 during 1980-2012. When the criteria were "softened" to < or = -1.7 degrees C in April and an interval of 16-37 days, 31 of 124 years met the conditions, and the yearly damage probability increased significantly to 0.19 for 1889-1979 and 0.42 for 1980-2012. In this forest, the combination of warming trends and temperature variability (extremes) associated with climate change is having ecologically important effects, making previously rare frost damage events more common.

Augspurger CK

2013-01-01

258

Winter climate controls soil carbon dynamics during summer in boreal forests  

International Nuclear Information System (INIS)

Boreal forests, characterized by distinct winter seasons, store a large proportion of the global terrestrial carbon (C) pool. We studied summer soil C-dynamics in a boreal forest in northern Sweden using a seven-year experimental manipulation of soil frost. We found that winter soil climate conditions play a major role in controlling the dissolution/mineralization of soil organic-C in the following summer season. Intensified soil frost led to significantly higher concentrations of dissolved organic carbon (DOC). Intensified soil frost also led to higher rates of basal heterotrophic CO2 production in surface soil samples. However, frost-induced decline in the in situ soil CO2 concentrations in summer suggests a substantial decline in root and/or plant associated rhizosphere CO2 production, which overrides the effects of increased heterotrophic CO2 production. Thus, colder winter soils, as a result of reduced snow cover, can substantially alter C-dynamics in boreal forests by reducing summer soil CO2 efflux, and increasing DOC losses. (letter)

2013-01-01

259

Metal stress consequences on frost hardiness of plants at northern high latitudes: a review and hypothesis  

Energy Technology Data Exchange (ETDEWEB)

This paper reviews the potential of trace/heavy metal-induced stress to reduce plant frost hardiness at northern high latitudes. The scientific questions are first outlined prior to a brief summary of heavy metal tolerance. The concepts of plant capacity and survival adaptation were used to formulate a hypothesis, according to which heavy metal stress may reduce plant frost hardiness for the following reasons: (1) Heavy metals change membrane properties through impaired resource acquisition and subsequent diminution of the cryoprotectant pool. (2) Heavy metals change membrane properties directly through oxidative stress, i.e. an increase of active oxygen species. (3) The involved co-stress may further increase oxidative stress. (4) The risk of frost injury increases due to membrane alterations. An opposite perspective was also discussed: could metal stress result in enhanced plant frost hardiness? This phenomenon could be based on the metabolism (i.e. glutathione, polyamines, proline, heat shock proteins) underlying a possible general adaptation syndrome of stress (GAS). As a result of the review it was suggested that metal-induced stress seems to reduce rather than increase plant frost hardiness. - Metal stress may reduce plant frost hardiness.

Taulavuori, Kari [Department of Biology, University of Oulu, PO Box 3000, FIN-90014, Oulu (Finland)]. E-mail: kari.taulavuori@oulu.fi; Prasad, M.N.V. [Department of Plant Sciences, University of Hyderabad, Hyderabad 500 046, Andhra Pradesh (India); Taulavuori, Erja [Department of Biology, University of Oulu, PO Box 3000, FIN-90014, Oulu (Finland); Laine, Kari [Department of Biology, University of Oulu, PO Box 3000, FIN-90014, Oulu (Finland)

2005-05-01

260

Frost hardiness gradients in shoots and roots of Picea mariana seedlings  

Energy Technology Data Exchange (ETDEWEB)

Frost hardiness of tissues along the length of the stem and the root was investigated in first-year black spruce (Picea mariana (Mill) B.S.P.) seedlings. Frost hardiness of 1 cm long stem and root segments was evaluated based on Index of Injury, calculated from post-freezing electrolyte leakage. Frost hardiness was tested approximately weekly beginning seven weeks after seedlings were transferred from an 18 to a 10 h photoperiod, both at day/night temperatures of 26 degrees C/16 degrees C. Trees were transferred to temperature of 10 degrees C day and 5 degrees C night at a 10 h photoperiod after a further 18 days. Frost hardiness was greater at the terminal bud and least at the root tips. Although shoots were generally more frost hardy than roots, differences in hardiness along the stem and root axes were gradual, rather than abruptly differing at the shoot-root interface. All tissues, including root tips, increased in frost hardiness after conditioning for 18 days under short photoperiods (10 h) and warm temperatures (26 degrees C/16 degrees C, day/night). Under cold temperatures (10 degrees C/5 degrees C, day/night) all tissues, excepting the root tips, tolerated - 16 degrees C with little subsequent electrolyte leakage. 20 refs, 2 figs

Colombo, S.J.; Zhao, S. [Ontario Forest Research Institute (Canada); Blumwald, E. [Univ. of Toronto (Canada). Centre for Plant Biotechnology

1995-05-01

 
 
 
 
261

An inverse geometry problem in estimating frost growth on an evaporating tube  

Energy Technology Data Exchange (ETDEWEB)

When humid air comes into contact with a surface whose temperature is below the dew point of water vapor in air and also below the freezing point, frost deposition takes place over the surface. The phenomena of the frost growth are very complicated and therefore it is very difficult to model mathematically the behavior of frost growth and predict it. In the present study a transient inverse geometry heat conduction problem (shape identification problem) is solved using the conjugate gradient method (CGM) and boundary element method (BEM)-based inverse algorithm to estimate the unknown irregular frost thickness and shape. Results obtained by using the CGM to estimate the frost growth are justified based on the numerical experiments. It is concluded that the accurate frost shape can be estimated by the CGM except for the initial and final time. The reason and improvement of this singularity are addressed. Finally the effects of reducing the number of sensors and increasing the measurement errors on the inverse solutions are discussed. (orig.)

Huang, C.H. [Department of Naval Architecture and Marine Engineering, National Cheng Kung University Tainan, Taiwan (Taiwan)

2002-08-01

262

Metal stress consequences on frost hardiness of plants at northern high latitudes: a review and hypothesis  

International Nuclear Information System (INIS)

This paper reviews the potential of trace/heavy metal-induced stress to reduce plant frost hardiness at northern high latitudes. The scientific questions are first outlined prior to a brief summary of heavy metal tolerance. The concepts of plant capacity and survival adaptation were used to formulate a hypothesis, according to which heavy metal stress may reduce plant frost hardiness for the following reasons: (1) Heavy metals change membrane properties through impaired resource acquisition and subsequent diminution of the cryoprotectant pool. (2) Heavy metals change membrane properties directly through oxidative stress, i.e. an increase of active oxygen species. (3) The involved co-stress may further increase oxidative stress. (4) The risk of frost injury increases due to membrane alterations. An opposite perspective was also discussed: could metal stress result in enhanced plant frost hardiness? This phenomenon could be based on the metabolism (i.e. glutathione, polyamines, proline, heat shock proteins) underlying a possible general adaptation syndrome of stress (GAS). As a result of the review it was suggested that metal-induced stress seems to reduce rather than increase plant frost hardiness. - Metal stress may reduce plant frost hardiness

2005-01-01

263

Decreased frost hardiness of Vaccinium vitis-idaea in reponse to UV-A radiation.  

UK PubMed Central (United Kingdom)

The aim of this study was to investigate plant frost hardiness responses to ultraviolet (UV) radiation, since the few results reported are largely contradictory. It was hypothesized that functional adaptation of life forms could explain these contradictions. Dwarf shrubs and tree seedlings, representing both evergreen and deciduous forms, were tested (Vaccinium vitis-idaea, Vaccinium myrtillus, Pinus sylvestris, Betula pubescens and its red form f. rubra). The research was performed in Sodankylä, Northern Finland (67°N), with enhanced UV-B- and UV-A-radiation treatments between 2002 and 2009. Plant frost hardiness was determined using the freeze-induced electrolyte leakage method in early autumn, during the onset of the frost hardening process. Additional physiological variables (malondialdehyde, glutathione, total phenols, C and N contents) were analyzed in V. vitis-idaea to explain the possible responses. These variables did not respond significantly to UV-radiation treatments, but explained the frost hardiness well (r² = 0.678). The main finding was that frost hardiness decreased in the evergreen shrub V. vitis-idaea, particularly with enhanced UV-A radiation. No significant responses were observed with the other plants. Therefore, this study does not support the idea that enhanced UV radiation could increase plant frost hardiness.

Taulavuori K; Keränen J; Suokanerva H; Lakkala K; Huttunen S; Laine K; Taulavuori E

2012-08-01

264

Dissecting the genetic architecture of frost tolerance in Central European winter wheat.  

Science.gov (United States)

Abiotic stress tolerance in plants is pivotal to increase yield stability, but its genetic basis is still poorly understood. To gain insight into the genetic architecture of frost tolerance, this work evaluated a large mapping population of 1739 wheat (Triticum aestivum L.) lines and hybrids adapted to Central Europe in field trials in Germany and fingerprinted the lines with a 9000 single-nucleotide polymorphism array. Additive effects prevailed over dominance effects. A two-dimensional genome scan revealed the presence of epistatic effects. Genome-wide association mapping in combination with a robust cross-validation strategy identified one frost tolerance locus with a major effect located on chromosome 5B. This locus was not in linkage disequilibrium with the known frost loci Fr-B1 and Fr-B2. The use of the detected diagnostic markers on chromosome 5B, however, does not allow prediction of frost tolerance with high accuracy. Application of genome-wide selection approaches that take into account also loci with small effect sizes considerably improved prediction of the genetic variation of frost tolerance in wheat. The developed prediction model is valuable for improving frost tolerance because this trait displays a wide variation in occurrence across years and is therefore a difficult target for conventional phenotypic selection. PMID:24006418

Zhao, Yusheng; Gowda, Manje; Würschum, Tobias; Longin, C Friedrich H; Korzun, Viktor; Kollers, Sonja; Schachschneider, Ralf; Zeng, Jian; Fernando, Rohan; Dubcovsky, Jorge; Reif, Jochen C

2013-09-04

265

The frost peat production; Routapalaturpeen tuotantoketjun tekniikka, talous ja ympaeristoevaikutukset  

Energy Technology Data Exchange (ETDEWEB)

The frost peat production means the cutting of frozen peat in winter time. The aim of this study is to test the possibilities to prolong the peat production season and to produce peat pieces for the horticultural peat industry. The tests of the production were carried out in Vihanti municipality in the Northern Ostrobothnia region during winters 1996 and 1997. In the method the frozen peat is sawn throughout the lengthwise and crosswise of the bog by a circle saw. The sawn peat blocks are loosened from the field by a block-lifter. The circle saw is equipped with five blades (diam. 90 cm). The distance between the blades is adjustable. The block lifter is equipped with a horizontal position blade (width 35 cm). The dimensions of the peat block are changeable, but from the point of drying the upper limit of the side of the peat cube is 15-20 cm. The frost peat production method is technically suitable for production of slightly decomposed (H1-5) energy and horticultural peat. The horticultural peat blocks must be transferred to a separate drying field, because on the cutting field the amount of the peat (about 1500-2000 m{sup 3}/ha) is far too much for drying. The peat blocks are spread out on the drying field by a self-unloading wagon. Well drained cutover fields are applicable as the drying fields. The energy peat blocks are allowed to dry up to 70-75 % moisture content on the cutting field and then the blocks can be ridged by a screening ridger. The ridges can, if necessary, be turned over. The amount of test production in the winter 1996 was about 5500 m{sup 3} and 1150 m{sup 3} in winter 1997. The measured output of the saw was about 45-50 m{sup 3}/h of energy peat and 55-60 m{sup 3}/h of horticultural peat. The output of the block-lifter was 120-160 m{sup 3}/h. Theoretically, the output of the saw and the block-lifter can easily be doubled. Thereafter the production costs will be about 19 FIM/MWh of energy peat and 18.6 FIM/m{sup 3} of horticultural peat. The share of snow removal from the cutting fields can be about 2 % and the cutting of peat 24 % of the production costs of the horticultural peat. (orig.) 1 ref., 2 tabs. BIOENERGY Research Programme

Nyroenen, T. [Vapo Oy, Jyvaeskylae (Finland); Leiviskae, V. [Oulu Univ. (Finland). Thule Institute

1998-12-01

266

The effect of stationary and sweeping frequency AC electric fields on frost crystal removal on a cold plate  

Energy Technology Data Exchange (ETDEWEB)

The effect of stationary and sweeping frequency AC electric fields on frost crystals growth and frost control/removal on a cold plate was studied for the first time in this paper. The main results of this study showed that the presence of AC electric fields can greatly affect both the frost crystals growth pattern and mass accumulation on cold surfaces. The ice surface electrical properties and basic electrostatics were used to explain the main findings in this paper. Up to 46% frost reduction was obtained when the electric field frequency spanned 370Hz to 7.5kHz while the applied voltage was 14.5kV. Two different sets of environmental conditions were tested, which showed that the plate temperature placed an important effect on frost crystals growth under electric fields. An optimum application time of the AC electric fields was found based on least frost mass accumulation on the cold plate. (author)

Tudor, V. [US Naval Academy, Annapolis, MD (United States). Advanced Thermal Systems Laboratory, Mechanical Engineering Department; Ohadi, M. [University of Maryland, College Park, MD (United States). Smart and Small Thermal Systems Laboratory, Mechanical Engineering Department

2006-06-15

267

Frost characteristics and heat transfer on a flat plate under freezer operating conditions: Part 2, Numerical modeling and comparison with data  

Energy Technology Data Exchange (ETDEWEB)

An existing numerical model for frost growth as a porous media is modified to include boundary conditions for a relatively high-density frost layer adjacent to a cold plate and turbulent airflow over a rough frost-air interface. Low-density frost grows on top of this high-density surface layer. Simulation results compare well with the data for selected test conditions where experimental uncertainty is small. When the experimental uncertainty is small, a validated physical/numerical model may be the best means of interpreting the physical nature of frost growth and extrapolating a limited database for frost growth.

Chen, H.; Besant, R.W.; Tao, Y.X.

1999-07-01

268

Minimising frost growth on cold surfaces exposed to humid air by means of crosslinked hydrophilic polymeric coatings  

Energy Technology Data Exchange (ETDEWEB)

Experiments have shown that frost growth on cold surfaces exposed to warm humid air streams can be reduced significantly by means of crosslinked hydrophilic polymeric coatings. This derives from the ability of these materials, under frosting conditions, to absorb available water, and hence retard the growth of frost when compared to an uncoated metallic surface. The extent of reduction of frost growth appeared to vary with the water absorbing potential of the polymer-coat, as well as its water content prior to frosting. In general, measurements in over two hours of testing, indicated that the reduction in frost growth rate and subsequently frost thickness lies in the range, 10-30%. The absorbed water improves the thermal conductivity of the polymeric coating. This, consequently, lowers the total thermal resistance between the air stream and the cold plate, and hence retards the frost surface temperature in its rise towards O{sup o}C an effect that would prolong the effective operation time of the thermal process before there is need for defrosting. Further observations made in this study tend to suggest that the nature of the frost formed with an air stream of low relative humidity (RH) differed from that resulting from a high RH air stream. (author)

Okoroafor, E.U.; Newborough, M. [Cranfield University, Bedford (United Kingdom). School of Mechanical Engineering

2000-06-01

269

The effect of surface contact angle on the behavior of frost formation in the fin-tube heat exchanger  

Energy Technology Data Exchange (ETDEWEB)

The effect of surface contact angle on the behavior of frost formation in the fin-tube heat exchanger is investigated experimentally. It is shown that both heat exchangers with hydrophilic and hydrophobic surfaces appear to have a better thermal performance than bare aluminium heat exchanger, but the improvements are very small. There is a little increase in the amount of the frost deposited onto the heat exchanger with both hydrophilic and hydrophobic surface. However, the effect of contact angle on the frost density is observed : the frost with high density forms on the heat exchanger with hydrophilic surface : and the frost with low density is deposited onto the heat exchanger with hydrophobic surface when compared with the frost deposited onto the heat exchanger with bare aluminium surface. This may be attributed to the fact that the shape of water droplets which condense on the surface of heat exchanger at the early stage of frosting varies with contact angle, and thus makes a difference on the structure of frost formation. From the experiments with different relative humidity of inlet air, it is shown that the variations of operating parameter make no influence on the effect of surface contact angle on the frosting behavior in the heat exchanger. (author). 10 refs., 9 figs.

Lee, K.S. [Hanyang University, Seoul (Korea); Jhee, S.; Lee, D.W. [Hanyang University, Graduate School, Seoul (Korea)

1999-11-01

270

Frost-free season lengthening and its potential cause in the Tibetan Plateau from 1960 to 2010  

Science.gov (United States)

Frost-free season was an important index for extreme temperature, which was widely discussed in agriculture and applied meteorology research. The frost-free season changed, which was associated with global warming in the past few decades. In this study, the changes in three indices (the last frost day in spring, the first frost day in autumn, and the frost-free season length) of the frost-free season were investigated at 73 meteorological stations in the Tibetan Plateau from 1960 to 2010. Results showed that the last frost day in spring occurred earlier, significantly in 39 % of the 73 stations. For the regional average, the last frost day in spring occurred earlier, significantly at the rate of 1.9 days/decade during the last 50 years. The first frost day in autumn occurred later, significantly in 31 % of the stations, and the regional average rate was 1.5 days/decade from 1960 to 2010. The changing rate of the first frost day in autumn below 3,000 m was 1.8 times larger than the changing rate above 3,000 m. In addition, the first frost day in autumn above 3,000 m fluctuated dramatically before the early 1990s and then it was later sharply after the early 1990s. The frost-free season length increased significantly at almost all stations in the Tibetan Plateau from 1960 to 2010. For the regional average, the frost-free season lengthened at the rate of 3.1 days/decade. The changing rate of the frost-free season length below 3,000 m was more significant than the changing rate above 3,000 m. Eight indices of large-scale atmospheric circulation were employed to investigate the potential cause of the frost-free season length change in the Tibetan Plateau during the past 50 years. There was a significant relationship between the frost-free season length and the Northern Hemisphere Polar Vortex indices. The weakening cold atmospheric circulation might be an essential factor to the Tibetan Plateau warming since 1960.

Zhang, Dan; Xu, Wenhui; Li, Jiayun; Cai, Zhe; An, Di

2013-04-01

271

Use of the delayed luminescence test for evaluation of changes in frost-resistance of winter wheat  

Directory of Open Access Journals (Sweden)

Full Text Available The influence of frost hardening conditions on the frost-resistance of three winter wheat cultivars ('Mironowska 808', 'Grana' and 'Maris Huntsman') was studied. Frost resistance was measured periodically during the autumn and winter season by the delayed luminescence method. Parallelly an electrical conductivity test was performed for comparison. It was found that the temperature which delayed luminescence reaches its maximum (tN) correlates with (t50) obtained by the conductometric method. The differences in response of particular cultivars to frost and hardening conditions are described.

Aleksander Brzóstowicz; Zdzis?aw Prokowski; Antoni Murkowski; Edward Grabikowski

1985-01-01

272

The effects of design and operating factors on the frost growth and thermal performance of a flat plate fin-tube heat exchanger under the frosting condition  

International Nuclear Information System (INIS)

An experimental study of the effects of various factors(fin pitch, fin arrangement, air temperature, air humidity, and air velocity) on the frost growth and thermal performance of a fin-tube heat exchanger has been conducted under the frosting condition. It is found that the thermal performance of a heat exchanger is closely related to the blockage ratio of the air flow passages due to the frost growth. The maximum allowable blockage ratio is used to determine the criteria for the optimal operating conditions of a fin-tube heat exchanger. It is also shown that heat transfer rate of heat exchanger with staggered fin arrangement increases about 17% and the time required for heat transfer rate to reach a maximum value becomes longer, compared with those of an inline fin-tube heat exchanger under the frosting condition. The energy transfer resistance between the air and coolant decreases with the increase of inlet air temperature and velocity and with decreasing inlet air humidity

1999-01-01

273

Laboratory evaluation of the effect of nitric acid uptake on frost point hygrometer performance  

Directory of Open Access Journals (Sweden)

Full Text Available Chilled mirror hygrometers (CMH) are widely used to measure water vapour in the troposphere and lower stratosphere from balloon-borne sondes. Systematic discrepancies among in situ water vapour instruments have been observed at low water vapour mixing ratios (3) with the measurement of frost point temperature, and consequently the water vapour mixing ratio, determined by CMH under conditions representative of operation in the UT/LS. No detectable interference in the measured frost point temperature was found for HNO3 mixing ratios of up to 4 ppb for exposure times up to 150 min. HNO3 was observed to co-condense on the mirror frost, with the adsorbed mass increasing linearly with time at constant exposure levels. Over the duration of a typical balloon sonde ascent (90–120 min), the maximum accumulated HNO3 amounts were comparable to monolayer coverage of the geometric mirror surface area, which corresponds to only a small fraction of the actual frost layer surface area. This small amount of co-condensed HNO3 is consistent with the observed lack of HNO3 interference in the frost point measurement because the CMH utilizes significant reductions (>10%) in surface reflectivity by the condensate to determine H2O.

T. Thornberry; T. Gierczak; R. S. Gao; H. Vömel; L. A. Watts; J. B. Burkholder; D. W. Fahey

2010-01-01

274

Laboratory evaluation of the effect of nitric acid uptake on frost point hygrometer performance  

Directory of Open Access Journals (Sweden)

Full Text Available Chilled mirror hygrometers (CMH) are widely used to measure water vapour in the troposphere and lower stratosphere from balloon-borne sondes. Systematic discrepancies among in situ water vapour instruments have been observed at low water vapour mixing ratios (3) with the measurement of frost point temperature, and consequently the water vapour mixing ratio, determined by CMH under conditions representative of operation in the UT/LS. No detectable interference in the measured frost point temperature was found for HNO3 mixing ratios of up to 4 ppb for exposure times up to 150 min. HNO3 was observed to co-condense on the mirror frost, with the adsorbed mass increasing linearly with time at constant exposure levels. Over the duration of a typical balloon sonde ascent (90–120 min), the maximum accumulated HNO3 amounts were comparable to monolayer coverage of the geometric mirror surface area, which corresponds to only a small fraction of the actual frost layer surface area. This small amount of co-condensed HNO3 is consistent with the observed lack of HNO3 interference in the frost point measurement because the CMH utilizes significant reductions (>10%) in surface reflectivity by the condensate to determine H2O.

T. Thornberry; T. Gierczak; R. S. Gao; H. Vömel; L. A. Watts; J. B. Burkholder; D. W. Fahey

2011-01-01

275

A Novel Approach to Study the Performance of Finned-Tube Heat Exchangers under Frosting Conditions  

Directory of Open Access Journals (Sweden)

Full Text Available Frost accumulation due to moist air flowing on a refrigeration coil cold surface impacts negatively on performance. The frost layer growth has an insulating effect in terms of heat transfer and causes the increase of the air pressure drop by blocking the free flow area across the coil. In this paper a new modeling approach, accounting for heat and mass transfer as well as the hydrodynamics of the problem, is proposed. A related FORTRAN program was developed, allowing the study of a large range of complex refrigerant circuit configurations. This model predicts the dynamic behavior of a refrigeration coil under dry and frosting conditions. Comparisons were made based on the frost mass accumulation and pressure drop across the coil and the results were found to agree reasonably well with experimental results reported in the literature. The model was then applied to study an evaporator typically employed in supermarkets. In terms of refrigerant temperature glide, it was shown that the glide decrease with time because of the decrease of the refrigeration capacity of the coil during the frosting. Further, the air pressure drop is strongly affected by the variation of the free flow area.

A.L. Bendaoud; M. Ouzzane; Z. Aidoun; N. Galanis

2011-01-01

276

Evaluation of the impact of frost resistances on potential altitudinal limit of trees.  

UK PubMed Central (United Kingdom)

Winter physiology of woody plants is a key issue in temperate biomes. Here, we investigated different frost resistance mechanisms on 1-year-old branches of 11 European tree species from November until budburst: (i) frost hardiness of living cells (by electrolyte leakage method), (ii) winter embolism sensitivity (by percentage loss of conductivity: PLC) and (iii) phenological variation of budburst (by thermal time to budburst). These ecophysiological traits were analyzed according to the potential altitudinal limit, which is highly related to frost exposure. Seasonal frost hardiness and PLC changes are relatively different across species. Maximal PLC observed in winter (PLCMax) was the factor most closely related to potential altitudinal limit. Moreover, PLCMax was related to the mean hydraulic diameter of vessels (indicating embolism sensitivity) and to osmotic compounds (indicating ability of living cells to refill xylem conducting elements). Winter embolism formation seems to be counterbalanced by active refilling from living cells. These results enabled us to model potential altitudinal limit according to three of the physiological/anatomical parameters studied. Monitoring different frost resistance strategies brings new insights to our understanding of the altitudinal limits of trees.

Charrier G; Cochard H; Améglio T

2013-09-01

277

Evaluation of the impact of frost resistances on potential altitudinal limit of trees.  

Science.gov (United States)

Winter physiology of woody plants is a key issue in temperate biomes. Here, we investigated different frost resistance mechanisms on 1-year-old branches of 11 European tree species from November until budburst: (i) frost hardiness of living cells (by electrolyte leakage method), (ii) winter embolism sensitivity (by percentage loss of conductivity: PLC) and (iii) phenological variation of budburst (by thermal time to budburst). These ecophysiological traits were analyzed according to the potential altitudinal limit, which is highly related to frost exposure. Seasonal frost hardiness and PLC changes are relatively different across species. Maximal PLC observed in winter (PLCMax) was the factor most closely related to potential altitudinal limit. Moreover, PLCMax was related to the mean hydraulic diameter of vessels (indicating embolism sensitivity) and to osmotic compounds (indicating ability of living cells to refill xylem conducting elements). Winter embolism formation seems to be counterbalanced by active refilling from living cells. These results enabled us to model potential altitudinal limit according to three of the physiological/anatomical parameters studied. Monitoring different frost resistance strategies brings new insights to our understanding of the altitudinal limits of trees. PMID:24052567

Charrier, Guillaume; Cochard, Hervé; Améglio, Thierry

2013-09-19

278

Short communication. Harvest time in hedgerow Arbequina olive orchards in areas with early frosts  

Energy Technology Data Exchange (ETDEWEB)

The shortening of harvest time attained in hedgerow olive (Olea europaea L.) orchards represents an advantage for the adoption of this cropping system in areas that are prone to suffer frost during the harvest period. To establish an optimal harvesting window, we carried out a study of the fruit ripening process on a hedgerow orchard of Arbequina olive trees, located in Zaragoza (Spain). From 2007 to 2009, oil accumulation on the fruit (% of dry weight) and oil yield (grams of oil per 100 fruits) were monitored, from early September to late November. Over the three years both variables peaked around November 15th, indicating that Arbequina reached full ripening earlier than has been reported previously for this variety. In two of the three seasons the orchard suffered several frosts during November. Long term climatic data from this area indicated that the risk of early frosts (< -2 degree centigrade) increases as November progresses with a high risk after November 20{sup t}h. In conclusion, the optimal harvesting period for Arbequina in this area should not extend beyond November 20{sup t}h. A rapid harvesting before this date is advisable to avoid the risk of damage caused by early frost in Zaragoza. Hedgerow planting provides an additional advantage in frost-prone areas, because mechanization of operations permits a short harvest period, easier to fit into the optimal harvesting window. (Author) 20 refs.

Gracia, P.; Sanchez-Gimeno, A. C.; Benito, M.; Oria, R.; Lasa, J. M.

2012-11-01

279

Numerical analysis on the frosting performance of a fin-tube evaporator for a refrigerator  

International Nuclear Information System (INIS)

The objective of this study is to provide numerical and experimental data that can be used to investigate the performance characteristics of a flat plate fin-tube evaporator in household and commercial refrigerators under frosting conditions. Computer simulations with variations of operating conditions such as air inlet temperature, relative humidity, and geometries were performed to find out optimal design parameters of a fin-tube evaporator for household and commercial refrigerators. The tube-by-tube method was used in the simulation and the frost growth model was considered under frosting conditions. The developed analytical model predicted the decreasing rates of heat transfer capacity and air flow rate ratio within ± 10% compared to the experimental results for a refrigerator under real operating conditions. As a result, the frost thickness at 3 .deg. C and 80% is increased 40% than that of -3 .deg. C and 80%, and the frost thickness at 3 .deg. C and 90% is increased 30% than that of 3 .deg. C and 60%. Accordingly, the operating time of the evaporator in the refrigerator was reduced with the increase of the decreasing rate of air flow rate ratio at each condition.

2008-01-01

280

Five second helium neutral beam injection using argon-frost cryopumping techniques  

Energy Technology Data Exchange (ETDEWEB)

High power helium neutral beams for the heating of tokamak discharges can now be provided for 5 s by using argon cryopumping (of the helium gas) in the beamlines. A system has now been installed to deposit a layer of argon frost on the DIII-D neutral beam cryopanels, between tokamak injection pulses. The layer serves to trap helium on the cryopanels providing sufficient pumping speed for 5 s helium beam extraction. The argon frosting hardware is now present on two of four DIII-D neutral beamlines, allowing injection of up to 6 MW of helium neutral beams per discharge, with pulse lengths of up to 5 s. The argon frosting system is described, along with experimental results demonstrating its effectiveness as a method of economically extending the capabilities of cryogenic pumping panels to allow multi-second helium neutral beam injection.

Phillips, J.C.; Kellman, D.H.; Hong, R.; Kim, J.; Laughon, G.M.

1995-10-01

 
 
 
 
281

Five second helium neutral beam injection using argon-frost cryopumping techniques  

International Nuclear Information System (INIS)

High power helium neutral beams for the heating of tokamak discharges can now be provided for 5 s by using argon cryopumping (of the helium gas) in the beamlines. A system has now been installed to deposit a layer of argon frost on the DIII-D neutral beam cryopanels, between tokamak injection pulses. The layer serves to trap helium on the cryopanels providing sufficient pumping speed for 5 s helium beam extraction. The argon frosting hardware is now present on two of four DIII-D neutral beamlines, allowing injection of up to 6 MW of helium neutral beams per discharge, with pulse lengths of up to 5 s. The argon frosting system is described, along with experimental results demonstrating its effectiveness as a method of economically extending the capabilities of cryogenic pumping panels to allow multi-second helium neutral beam injection

1995-01-01

282

Effect of sodium monofluorophosphate treatment on microstructure and frost salt scaling durability of slag cement paste  

International Nuclear Information System (INIS)

Sodium-monofluorophosphate (Na-MFP) is currently in use as a surface applied corrosion inhibitor in the concrete industry. Its basic mechanism is to protect the passive layer of the reinforcement steel against disruption due to carbonation. Carbonation is known as the most detrimental environmental effect on blast furnace slag cement (BFSC) concrete with respect to frost salt scaling. In this paper the effect of Na-MFP on the microstructure and frost salt scaling resistance of carbonated BFSC paste is presented. The results of electron microscopy, mercury intrusion porosimetry (MIP) and X-ray diffraction (XRD) are discussed. It is found that the treatment modifies the microstructure and improves the resistance of carbonated BFSC paste against frost salt attack

2006-01-01

283

Environmental controls of frost cracking revealed through in situ acoustic emission measurements in steep bedrock  

Science.gov (United States)

Frost cracking, the breakdown of rock by freezing, is one of the most important mechanical weathering processes acting on Earth's surface. Insights on the mechanisms driving frost cracking stem mainly from laboratory and theoretical studies. Transferring insights from such studies to natural conditions, involving jointed bedrock and heterogeneous thermal and hydrological properties, is a major challenge. We address this problem with simultaneous in situ measurements of acoustic emissions, used as proxy of rock damage, and rock temperature/moisture content. The 1 year data set acquired in an Alpine rock wall shows that (1) liquid water content has an important impact on freezing-induced rock damage, (2) sustained freezing can yield much stronger damage than repeated freeze-thaw cycling, and (3) that frost cracking occurs over the full range of temperatures measured extending from 0 down to -15°C. These new measurements yield a slightly different picture than previous field studies where ice segregation appears to play an important role.

Girard, Lucas; Gruber, Stephan; Weber, Samuel; Beutel, Jan

2013-05-01

284

Experimental Study on Frost Height of Round Plate Fin-Tube Heat Exchangers for Mobile Heat Pumps  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The objective of this study was to provide experimental data that could be used to predict frost growth and frost performance of a round plate fin-tube heat exchanger for low temperature heat pumps used in zero emission vehicles under cold weather conditions. In this study, round plate fin-tube heat...

Moo-Yeon Lee; Yongchan Kim; Dong-Yeon Lee

285

In-situ test on frost heave at highway embankment; Doro moritsuchi ni okeru genchi tojo shiken  

Energy Technology Data Exchange (ETDEWEB)

Preventive measures against frost heave of roads are a large study subject in road construction in Hokkaido, Tohoku and other cold districts because a huge sum of money is necessary for repair of roads when once frost heave occurs. A large-scale laboratory experiment is being carried out to estimate the possibility of frost heave focusing attention on ground water table, and the characteristic relation between the position of ground water tables and the quantity of frost heave was found. For study on a frost heave behavior on actual roads, the frost heave test yards with different ground water tables and replacement rates of difficult-to- freeze materials were prepared in Asahikawa-Takasu I.C. and Obihiro-Hokumei area. The observation result at the frost heave test yards and the laboratory experiment result showed that the ground water table has strong effect on the quantity and rate of frost heave, and the quantity decreased with an increase in depth of the ground water table. Reduction of the replacement rate is also possible at embankments with relatively deep ground water tables. 6 refs., 8 figs., 3 tabs.

Yokota, S.; Mishima, N. [Japan Highway Public Corporation, Tokyo (Japan); Miura, S. [Muroran Institute of Technology, Hokkaido (Japan)

1997-11-01

286

Effect of frost damage on leaf macronutrient status of eight apple cultivars in integrated apple orchard in Eastern-Hungary  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The year of 2007 was critical for fruit growers in the region of Easter-Hungary. Several orchards were suffered frost damages. Significant frost damage was also happened in the orchard of Tedej Rt., which caused total fruit failure in the orchard. Our study was conducted in the integrated apple orc...

Nagy PT; Kátai J, Nyéki J; Szabó Z; Nagy Péter Tamás (1970-) (vegyész)

287

Influence of low temperature and frost duration on Phytophthora alni subsp. alni viability  

Energy Technology Data Exchange (ETDEWEB)

Limits on the survival of P. alni subsp. alni (PAA) due to low temperature can be expected based on previously published laboratory and field studies. This study presents a laboratory experiment to test the influence of low temperature and frost duration on PAA viability. Ten PAA isolates were incubated at different temperatures (-0.1, -2.5, -5.0, -7.5, and -10.0 degree centigrade) and frost durations (0 - 7, 14, 21, and 28 days). A regression analysis confirmed the significant influence of both factors (low temperature and frost duration, and their interaction) on the survival of the pathogen under laboratory conditions. The survival and failure time analysis showed that the survival of the pathogen differs significantly after mild frost (all the isolates tested survived temperatures between -0.1 and -5.0 degree centigrade during the entire testing period) and heavy frost (the pathogen died after 21 days of incubation at -7.5 degree centigrade and after 2 days at -10.0 degree centigrade). Moreover, the viability of the pathogen decreased significantly if the temperature of -5.0 degree centigrade was maintained for at least 1 week and the temperature of -7.5 degree centigrade persisted in laboratory conditions for at least 4 days. The results of the study proved the pathogen to be very sensitive to heavy frost. The low-temperature limits for PAA occur regularly in Central Europe in January. It is probable that these temperatures can reduce PAA populations in diseased black alder stems. The climate change characterised by increases in the lowest minimum winter temperatures in Central Europe (as hypothesised by IPCC) may pose a significant risk for affected alder population in the area. (Author) 21 refs.

Cerny, K.; Filipova, N.; Strnadova, V.

2012-11-01

288

Association analysis of frost tolerance in rye using candidate genes and phenotypic data from controlled, semi-controlled, and field phenotyping platforms  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Abstract Background Frost is an important abiotic stress that limits cereal production in the temperate zone. As the most frost tolerant small grain cereal, rye (Secale cereale L.) is an ideal cereal model for investigating the genetic basis of frost tolerance (FT), a compl...

Li Yongle; Böck Andreas; Haseneyer Grit; Korzun Viktor; Wilde Peer; Schön Chris-Carolin; Ankerst Donna P; Bauer Eva

289

Effects of air flow maldistribution on refrigeration system dynamics of air source heat pump chiller under frosting conditions  

International Nuclear Information System (INIS)

The effects of air flow maldistribution on the performance of an air source heat pump chiller under frosting conditions were investigated experimentally. The results indicated that air flow maldistribution was the dominant factor leading to hunting of the thermostatic expansion valve for medium and/or large size finned tube evaporators. With air flow maldistribution degree (AMD) increasing, frost occurred earlier, and the frost layer grew faster. The operating characteristics became lower when AMD was increased. We found such phenomenon seemed to be related to both the difference of refrigerant outlet superheat and the frosting velocity. In the hunting stage, the frost block effect became the main factor degrading the refrigeration system performance. With AMD increasing, the heat pump system pertinent performance data (suction pressure, evaporation temperature, discharge pressure, refrigerant outlet temperature, etc.) were degraded more dramatically

2008-01-01

290

Heat transfer and pressure drop amidst frost layer presence for the full geometry of fin-tube heat exchanger  

International Nuclear Information System (INIS)

The present study numerically solves the flow and thermal fields in the full geometry of heat exchanger modeling with frost layer presence on the heat exchanger surface. The effects of air inlet velocity, air inlet temperature, frost layer thickness, fin pitch, fin thickness, and heat exchanger shape on the thermo-hydraulic performance of a fin-tube heat exchanger are investigated. Heat transfer rate rises with increasing air inlet velocity and temperature, and decreasing frost layer thickness and fin pitch. Pressure drop rises with increasing air inlet velocity and frost layer thickness, and decreasing fin pitch. The effect of fin thickness on heat transfer and pressure drop is negligible. Based on the present results, we derived the correlations, which express pressure drop and temperature difference between air inlet and outlet as a function of air inlet velocity and temperature, as well as frost layer thickness

2010-01-01

291

Effects of air flow maldistribution on refrigeration system dynamics of air source heat pump chiller under frosting conditions  

Energy Technology Data Exchange (ETDEWEB)

The effects of air flow maldistribution on the performance of an air source heat pump chiller under frosting conditions were investigated experimentally. The results indicated that air flow maldistribution was the dominant factor leading to hunting of the thermostatic expansion valve for medium and/or large size finned tube evaporators. With air flow maldistribution degree (AMD) increasing, frost occurred earlier, and the frost layer grew faster. The operating characteristics became lower when AMD was increased. We found such phenomenon seemed to be related to both the difference of refrigerant outlet superheat and the frosting velocity. In the hunting stage, the frost block effect became the main factor degrading the refrigeration system performance. With AMD increasing, the heat pump system pertinent performance data (suction pressure, evaporation temperature, discharge pressure, refrigerant outlet temperature, etc.) were degraded more dramatically. (author)

Gong, Jianying; Gao, Tieyu; Yuan, Xiuling; Huang, Dong [Department of Refrigeration and Cryogenics, Xi' an Jiao Tong University, Xi' an 710049 (China)

2008-06-15

292

Effects of air flow maldistribution on refrigeration system dynamics of air source heat pump chiller under frosting conditions  

Energy Technology Data Exchange (ETDEWEB)

The effects of air flow maldistribution on the performance of an air source heat pump chiller under frosting conditions were investigated experimentally. The results indicated that air flow maldistribution was the dominant factor leading to hunting of the thermostatic expansion valve for medium and/or large size finned tube evaporators. With air flow maldistribution degree (AMD) increasing, frost occurred earlier, and the frost layer grew faster. The operating characteristics became lower when AMD was increased. We found such phenomenon seemed to be related to both the difference of refrigerant outlet superheat and the frosting velocity. In the hunting stage, the frost block effect became the main factor degrading the refrigeration system performance. With AMD increasing, the heat pump system pertinent performance data (suction pressure, evaporation temperature, discharge pressure, refrigerant outlet temperature, etc.) were degraded more dramatically.

Gong Jianying [Department of Refrigeration and Cryogenics, Xi' an Jiao Tong University, Xi' an 710049 (China)], E-mail: gong-jianying@163.com; Gao Tieyu; Yuan Xiuling; Huang Dong [Department of Refrigeration and Cryogenics, Xi' an Jiao Tong University, Xi' an 710049 (China)

2008-06-15

293

Evaluations on power ramp data of PWR fuels by FROST and THERMOST codes  

International Nuclear Information System (INIS)

An evaluation is presented of power ramp data of Mitsubishi's PWR fuel rods tested in R-2, Studsvik, which was analysed by FROST and THERMOST codes. The analyses give good predictions for measured diameter changes and on-power rod elongations. The work indicates that FROST is capable of analysing both radial and axial pellet-cladding mechanism interaction (PCMI) appropriately, and that predicted states of PCMI (i.e. stress and strain which cannot be measured directly) are considered to be reliable. The ramp data used in the present analyses were obtained in two joint programmes with five Japanese PWR utilities (KEPCO, KYEPCO, SEPCO, HEPCO, and JAPCO). (UK)

1987-01-01

294

Near infrared reflectance spectra and analysis of H2S frost as a function of temperature  

International Nuclear Information System (INIS)

The reflection spectra of H2S frost in the near infrared region (1.6--4 ?m), as a function of temperature to 62 degreeK, were measured. Analyses of these spectra were made, and assignments for the most intense combinations attempted. Dramatic changes in spectra are observed from 62--143 degreeK, connected with a phase transition between a tetragonal, low-temperature phase and a cubic, high-temperature phase, occurring at 125 +- 5 degreeK. The data present evidence for only two phases being involved for H2S frost

1977-07-15

295

David Sanders. A Divided Poet: Robert Frost, North of Boston, and the Drama of Disappearance.  

Directory of Open Access Journals (Sweden)

Full Text Available David Sanders in his monograph entitled A Divided Poet: Robert Frost, North of Boston, and the Drama of Disappearance (2011) sheds light on the dilemmas, doubts and personal conflicts Frost confronted while composing his poetic collection North of Boston in which some of his most well-known lyrics, such as “Mending Wall,” “After Apple-Picking,” and “The Wood-Pile,” are contained. This book should be considered alongside a number of other publications either in monograph or essay form that app...

Tatiani G. Rapatzikou

2012-01-01

296

Climate warming and the risk of frost damage to boreal forest trees : identification of critical ecophysiological traits  

Energy Technology Data Exchange (ETDEWEB)

Eco-physiological traits critical to the occurrence of frost damage in trees in the boreal zone were identified. Two computer simulations were used to examine why 1 simulation predicted heavy frost damage as a consequence of climate warming, while another closely related model did not. The 2 models were developed and parametrized to predict the annual cycle of frost hardiness of trees in central Finland. Model{sub 1} was developed for a theoretical generalized tree species. Model{sub 2} was developed and parametrized to predict needle frost hardiness of Scots pine. Four conceptual traits were used to describe the environmental regulation of ontogenetic development during the ontogenetic phases of growth, lignification, rest and quiescence. The cycle of frost hardiness was developed as a 2-step process. Annual ontogenetic development was modelled with air temperature and night length as the driving forces. The rate of frost hardening and dehardening was then modelled as a function of air temperature, night length and the prevailing phase of the annual ontogenetic cycle. The process was carried out in both models by calculating the rate of change of frost hardiness as a first-order dynamic process. Examination of the risk of frost damage was based on mean values rather than the corresponding maxima of needle damage over the 92 cycles examined. The modelling comparison indicated that the response rates of ontogenetic development during quiescence to air temperature is a critical trait for the risk of frost damage following climate warming. It was suggested that determining the form of the non-linear response is crucial to the assessment of climate warming impacts. Results indicated that predictions of the risk of increased frost damage to trees in response to climate warming remain equivocal. It was concluded that further experimental work with a variety of tree species is needed. 57 refs., 1 tab., 7 figs.

Hanninen, H. [Helsinki Univ., Helsinki (Finland). Plant Ecophysiology and Climate Change Group

2006-07-15

297

Effects of frost on wildflowers: an unexpected consequence of climate change--Image 05 of 22  

Science.gov (United States)

A flowering plant of Helianthella quinquenervis (aspen sunflower, Asteraceae) at the Rocky Mountain Biological Laboratory. This species has flower buds that are frost-sensitive. The plants have a mutualism with ants, which are attracted by extrafloral nectar secreted by the bracts that cover flower buds.

Inouye, David

2012-01-04

298

The influence of ageing on the salt-frost resistance of concrete  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Abstract This thesis presents the results of an investigation of the influence of ageing on the salt-frost resistance of concrete. The ageing mechanisms investigated were hydration, drying and carbonation. Specimens of ‘micro’-concrete, either with OPC alone as the binder or with silica or slag as p...

Utgenannt, Peter

299

Use of Gibberellins to Improve Fruit Set in Pears After Frost Damage  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The objectives of this study were to investigate the effect of applied bioregulators on fruit set after this frost in April 2002, growth, yield and the incidence of Pseudomonas syringae and the understanding of the underlying mechanisms of fruit set by applying bioregulators shortly after ful...

George Ouma

300

Effects of frost on wildflowers: an unexpected consequence of climate change--image 15 of 22  

Science.gov (United States)

Photo of an early-stage inflorescence of tall larkspur (Delphinium barbeyi) after a mid-June snowstorm at the Rocky Mountain Biological Laboratory. The buds were killed by the cold temperature. Like Helianthella quinquenervis, D. barbeyi is a frost-sensitive species.

Inouye, David

2012-01-04

 
 
 
 
301

Frost resistance of concrete in artic offshore structures. Betonin pakkasenkestaevyys arktisissa merirakenteissa  

Energy Technology Data Exchange (ETDEWEB)

In the literature part of this work the nature of frost attack in arctic offshore conditions is studied and reguirements for concrete according to literature in arctic offshore conditions are presented. Frost action has been examined theoretically. In the theoretical examinations the hydraulic pressure theory and the capillary ice lens segregation theory are studied. Both theories are applied to arctic offshore conditions. The aim of the experiments was to examine the effects of the pore structure on the frost resistance under an arctic freezing and thawing attack. Freezing and thawing resistance was tested with a new test method developed at VTT. Specimens were submerged in sea water and subjected to repeated freezing at the temperature of -55 deg C and thawing at +20 deg C. The pore structure of hardened concrete was determined by optical air pore analysis. Capillary water absorption test and protective pore ratio test were performed as well. The pore structure of each binder type was measured with the mercury intrusion porosimeter. On the basis of the test results the criteria for ensuring the frost resistance are given.

Leivo, M. (9698851FI)

1989-05-01

302

Frost damage suppression effect of surface treating materials; Hyomen shorizai ni yoru togai yokusei koka  

Energy Technology Data Exchange (ETDEWEB)

Experiments were carried out on frost damage suppression effect of surface treating materials on concrete. Frost damage under actual environment is caused by drying by sunshine and water supply from snow and rain, in addition to freezing and thawing actions. Therefore, tests were performed with the drying and water supplying processes added to the conventional freezing and thawing test method. If surface treatment is given in sound condition (with relative dynamic elasticity coefficient of 100%), surface treating materials of any type can enhance the frost damage resistance. Although the frost damage resistance was enhanced even in a condition with the surface layer having been deteriorated (with the relative dynamic elasticity coefficient of 80%), the surface treating material of coating film system (acrylilic rubber system) was found slightly inferior to the permeation system (alkali silicate system). In the case of the coating film system, in which the surface is protected by thick coating film, apparent damage is not noticed so remarkably even if the deterioration has progressed, but the relative dynamic elasticity coefficient has decreased. In the test performed presently, the test sample surface can be transferred to the freezing and thawing process with the surface kept wet by means of spraying after completion of the drying process in addition to freezing and thawing. Thus, the test method can be said one incorporating the natural environmental conditions to some extent. (NEDO)

Misumi, N. [Kansai Electric Power Co. Inc., Osaka (Japan)

2000-05-10

303

Frost flower chemical signature in winter snow on Vestfonna ice cap, Nordaustlandet, Svalbard  

Directory of Open Access Journals (Sweden)

Full Text Available The chemistry of snow and ice cores from Svalbard is influenced by variations in local sea ice margin and distance to open water. Snow pits sampled at two summits of Vestfonna ice cap (Nordaustlandet, Svalbard), exhibit spatially heterogeneous soluble ions concentrations despite similar accumulation rates, reflecting the importance of small-scale weather patterns on this island ice cap. The snow pack on the western summit shows higher average values of marine ions and a winter snow layer that is relatively depleted in sulphate. One part of the winter snow pack exhibits a [SO42-/Na+] ratio reduced by two thirds compared with its ratio in sea water. This low sulphate content in winter snow is interpreted as the signature of frost flowers, which are formed on young sea ice when offshore winds predominate. Frost flowers have been described as the dominant source of sea salt to aerosol and precipitation in ice cores in coastal Antarctica but this is the first time their chemical signal has been described in the Arctic. The eastern summit does not show any frost flower signature and we interpret the unusually dynamic ice transport and rapid formation of thin ice on the Hinlopen Strait as the source of the frost flowers.

E. Beaudon; J. Moore

2009-01-01

304

Frost flower chemical signature in winter snow on Vestfonna ice cap (Nordaustlandet, Svalbard)  

Directory of Open Access Journals (Sweden)

Full Text Available The chemistry of snow and ice cores from Svalbard is influenced by variations in local sea ice margin and distance to open water. Snow pits sampled at two summits of Vestfonna ice cap (Nordaustlandet, Svalbard), exhibit spatially heterogeneous soluble ions concentrations despite similar accumulation rates, reflecting the importance of small-scale weather patterns on this island ice cap. The snow pack on the western summit shows higher average values of marine species and a winter snow layer that is relatively depleted in sulphate. One part of the winter snow pack exhibits [SO42-/Na+] ratio reduced by two thirds compared with its ratio in sea water. This low sulphate content in winter snow is interpreted as the signature of frost flowers, which are formed on young sea ice when offshore winds predominate. Frost flowers have been described as the dominant source of sea salt to aerosol and precipitation in ice cores in coastal Antarctica but this is the first time their chemical signal has been described in the Arctic. The eastern summit does not show any frost flower signature and we interpret the unusually dynamic ice transport and rapid formation of thin ice on the Hinlopen Strait as the source of the frost flowers.

E. Beaudon; J. Moore

2009-01-01

305

Production losses due to a summer frost in a Salix viminalis short rotation forest in southern Sweden  

Energy Technology Data Exchange (ETDEWEB)

The effect of a single night frost during late spring on the current year production of two clones of Salix viminalis was determined in two monoclonal stands that displayed a gradient from virtually undamaged plants, shielded from outgoing radiation by a neighbouring spruce forest, to heavily damaged plants in the unshielded parts. Compared with the undamaged stand parts, frost caused production losses of 47% and 60% in the two clones during the first year of the second cutting cycle. The clone-specific allometric relationship between shoot dry weight and diameter was changed by the frost in one clone, showing lower shoot weights in damaged shoots compared with undamaged shoots of the same diameter. In the other clone, allometric relations were not affected by the frost. The relative variation in weight between the stools did not differ systematically with frost damage intensity, and therefore it could not be concluded that frost in monoclonal stands would enforce a competitive hierarchy. It was inferred that the single night frost indirectly can have a negative effect on the production of the stands during the years to come.

Verwijst, T.; Elowson, S. [Swedish Univ. of Agricultural Sciences, Uppsala (Sweden). Dept. of Ecology and Environmental Research; Xuemin Li [Jianping Forestry Bureau, LN (China); Guoyou Leng [Huaibei Coal Mine Bureau, AH (China). Dept. of Forestry

1996-06-01

306

Frost deposition on cooled surfaces under reduced pressure; Gen`atsuka no suihei reikyaku menjo ni okeru ketsuro seicho  

Energy Technology Data Exchange (ETDEWEB)

Deposition rates and growth rates of frost on cooled surfaces under reduced pressure were obtained by using a freezing apparatus to reproduce natural convection where an upper surface was cooled at constant temperature and water was evaporated from a lower surface. It was designed for a basic study of a cryogenic freezer proposed for a fuel clean-up system of a fusion reactor. The experiment was carried out in the ranges of 6{times}l0{sup 2}Pa to 1{times}10{sup 5}Pa of total pressure and 77 K to 261 K of the cooling temperature. Sh numbers at the initial stage of frosting could be fitted to values evaluated using a conventional correlation of natural convection multiplied by a factor based on the critical supersaturation model. Frost thickness and average frost density under reduced pressure grew with the square root of time. In addition, frost thickness increased with [(T{sub S1}-T{sub W1})t]{sup 0.5} over all the ranges of the experimental conditions except where frost melted on the interface. The difference in frost thickness with the total pressure was qualitatively correlated by a parameter which was defined by the ratio of latent heat flux to sensitive heat flux. 21 refs., 8 figs.

Fukada, S.; Inoue, K.; Nishikawa, M. [Kyushu University, Fukuoka (Japan)

1995-01-15

307

An experimental investigation of the effect of hydrophobicity on the rate of frost growth in laminar channel flows  

Energy Technology Data Exchange (ETDEWEB)

An experimental investigation of the effect of the substrate on frost growth rate is presented. Measurements of frost height as a function of time are presented for a flat, bare, horizontally oriented aluminum substrate and four coated substrates, two hydrophilic and two hydrophobic. The average frost growth rate on the hydrophilic coated aluminum substrate is 13% higher than the control substrate, while the frost growth rate on the hydrophilic kapton substrate is 4% higher. Frost grows on the hydrophobic substrates at a rate 19% and 3% lower than the reference substrate for the polytetrafluoroethylene (PTFE) coated steel and PTFE tape, respectively. Differences in the receding and advancing contact angles for these substrates do not fully explain the difference in growth rates. Differences in initial water deposition, freezing, and frost growth on hydrophilic and hydrophobic substrates are examined using confocal microscopy. On the basis of the microscopic observations, the authors hypothesize that the water coverage on the substrate before and after freezing can affect the thermal resistance of the mature frost layer. Differences in thermal resistance, in turn, affect the growth rate.

Dyer, J.M.; Storey, B.D.; Hoke, J.L.; Jacobi, A.M.; Georgiadis, J.G.

2000-07-01

308

?????????1961~2009??????????? Characteristics of the Frost-Free Season Changes from 1961 to 2009 in Northwest China  

Directory of Open Access Journals (Sweden)

Full Text Available ????????135????1961~2009????????????????????????????Mann-Kendall????????????????????????49 a?????????????????????1) ?????????????????–?????220 d??????????????????200?d???????????????????????3??????????120 d~140 d?????–??150 d~160 d?2) ??????????3.8 d/10 a??????1987???????????49?????????3????3) ?????90%????2~5 d/10 a??????????????????1960~1970?????????????1980???????1990???58%??????10???92%????????4) ??????????????????????????????????????????????????? Using the daily surface minimum air temperature data of 135 observational stations from 1961 to 2009 in Northwest of China and average temperature data, with the methods linear trend analysis, Mann-Kendall, Moving T-examination, wavelet analysis, power spectrum and so on, analyzed climatic variation characteristics of the frost-free season of Northwest China in recent 49 years. The results show that: 1) The frost-free season is the longest place in South Gansu, South Shanxi which has 220 days, and next is South Xinjiang Basin which has 210 days. The frost-free season is the shortest place in the Qinghai Plateau which is shorter than for three months. Other place, It has about 120 d - 140 d in northern Xinjiang-Gansu Corridor and 150 d - 160 d in Gansu East of the river, North Shaanxi; 2) The average frost-free season postpone at a rate of 3.8 d/10 a, whole area postpone 18 days. There is an abrupt change in 1987. The frost-free season have the remarkable 3 year periods in recent 49 year; 3) There are 90% stations that the frost-free season postpone, and majority area postpone by speed of 2 - 5 d/10 a. Looked through the interdecadal climatic trends, since 1980 ages have 50% above station to be increase, especially in the recent 10 years, have the close 92% station to be increase; 4) Is changed the climate warm influence , the cold date number reduces, the last frost ahead of time, the first frost postpone, the frost-free season lengthens. But to the frost-free season contribution, the last frost is higher than the first frost.  

???; ???; ???; ???

2012-01-01

309

The risk of early and late frost behavior in central México under El Niño conditions  

Scientific Electronic Library Online (English)

Full Text Available Abstract in spanish El problema de la presencia irregular de bajas temperaturas (heladas) en el centro de México (~19-23° N) causa pérdidas elevadas en la producción agrícola año tras año, afectando principalmente a cultivos que son sensibles a las temperaturas bajas con importantes implicaciones socioeconómicas. En el centro de México, existe carencia de estudios sobre las heladas en relación a su duración especialmente en respuesta al fenómeno de El Niño (EN). Debido a la acci (more) dentada orografía del terreno las estaciones climatológicas se agruparon en rangos de 300 m de altura, resultando cinco regiones: I, III, IV-VI con elevaciones de 875 a 2999 msnm, conformadas por 50 estaciones con datos de temperaturas mínimas diarias (< 2 °C) de 1960 a 1998. Nuestros resultados indican (aunque no significativamente) que durante años EN se presenta la primera helada en las cinco regiones bajo estudio y durante años neutrales (N) se presenta la última helada en las regiones más altas (IV-VI). Durante EN, el período libre de heladas (PLH) es más corto que para años N, excepto en la región VI donde fue más corto para años N. Se determinó también la ocurrencia de heladas con 20% de probabilidad de ocurrencia por regiones y para las estaciones con los PLH más cortos. Las pruebas de regresión entre las fechas de ocurrencia de heladas y la elevación, indican que la presencia de heladas está más correlacionada con la altitud del lugar que con los eventos EN y N; los lugares con mayor elevación presentaron PLH más reducidos comparados con los de menor altitud. Abstract in english The irregular occurrence of cold temperatures (frost) in central México (~19-23° N) produces high agricultural losses each year; the greatest effect is on cold-sensitive crops, which has important socio-economic implications for the region. There is a lack of information on frost-related studies regarding the onset and duration of frosts in central México, especially in response to the El Niño (EN) phenomenon. Due to the land's irregular topography, the weather statio (more) ns were grouped into 300 m range heights, resulting in five regions: I, III, and IV-VI with elevations from 875 to 2999 masl. Daily minimum temperatures (< 2 °C) from 50 weather stations and for each year from 1960 through 1998 were analyzed. The EN effect was evaluated by region comparing the frost-free period (FFP) for EN vs. neutral (N) events. Our results (although not statistically significant) show that the first frost occurs during EN years in the five regions under study; the last frost occurs in the highest regions (IV-VI) during N years. Also, during EN, the FFP is shorter than for N years, except in region VI where it was shorter during N years. The probability of frost occurrence at a 20% level was determined for stations with the shortest FFP. Regression analysis between frost periods and elevation show that frost occurrence is better correlated with elevation than with EN and N events; areas with higher elevation showed shorter FFP compared to areas with lower elevation.

PERALTA-HERNÁNDEZ, A. R; BARBA-MARTÍNEZ, L. R

2009-01-01

310

Índice de riesgo sistémico de heladas (IRISH)/ Sistemic frost risk index (SFRI)  

Scientific Electronic Library Online (English)

Full Text Available Abstract in spanish El objetivo principal de este trabajo es la presentación de los fundamentos y metodología del IRiSH. Se utilizaron temperaturas horarias de cinco observatorios para el período 1991-2003 para calcular la duración de las heladas producidas en ese período y analizar su asociación con la temperatura mínima. Para el desarrollo del IRiSH se utilizaron las temperaturas mínimas diarias del período 1964-2003. Se asume que las heladas tardías serán tanto más peligrosas (more) cuanto más se adelante la fenología del cultivo o se retrasen las heladas, cuanto mayor sea su intensidad, su duración y su frecuencia. El IRiSH integra todas estas variables directa o indirectamente. Se describen, a modo de ejemplo, las funciones empíricas desarrolladas para el cálculo del índice correspondiente al cultivo de trigo. El resultado es un índice de gran versatilidad, aplicable a distintos cultivos, que tiene en cuenta las principales variables determinantes de la peligrosidad de las heladas. Permite el monitoreo del riesgo de heladas durante el año, así como estudiar su variabilidad interanual, su tendencia temporal y su variación espacial. Con promedios anuales para una serie de años posibilita también la caracterización climática media del riesgo de heladas. Abstract in english The aim of this study is to present the fundamentals and methodology of the SFRi. Hourly temperatures of five observatories for the period 1991-2003 were used to calculate the duration of frosts and analyse their relationship with the minimum temperature. Daily minimum temperatures from the period 1964-2003 were used for the development of the SFRi. We assume that late frosts will be more dangerous the sooner the phenology of the crop or the more delayed the frosts, also (more) the greater their intensity, length and frequency. The IRiSH integrates all these variables directly or indirectly. We describe, as an example, the empirical functions developed for calculating the index for wheat cultivation. The result is a versatile index, applicable to different crops, which takes into account the main variables that determine the level of danger from frosts. It allows to monitor frosts risk during the year, and to examine their inter-annual variability, temporal trend and special distribution. With annual averages for many years it also allows for the climatic characterization of frosts risk.

Fernández Long, María Elena; Murphy, Guillermo; Torterolo, María Karina

2008-03-01

311

Biological control of frost injury: an isolate of Erwinia herbicola antgonistic to ice nucleation active bacteria.  

UK PubMed Central (United Kingdom)

10.1094/Phyto-73-1097. Treatment of corn (Zea mays L.) seedlings in a growth chamber with an Erwinia herbicola isolate (M232A) that was not active in ice nucleation decreased the amount of frost damage incited by ice nucleation active (INA) isolates of Pseudomonas syringae and E. herbicola at - 5 C. The percentage of leaves damaged by frost decreased significantly if M232A was applied at any time before, and up to 12 hr after, application of an INA E. herbicola isolate. Frost damage decreased with increased densities of M232A (105 to 109 cfu/ml) applied 24 hr before challenging with an INA isolate of E. herbicola (8 x 105 or 8 x 106 cfu/ml). Plants sprayed with 3 x 108 colony-forming units (cfu) per milliliter M232A 24 hr prior to application of INA isolates of E. herbicola or P. syringae sustained less damage than did plants without M232A populations, regardless of the cell densities of INA bacteria applied. From 88 to 100% reduction in frost damage was observed in the presence of M232A on plants challenged by less than ~106 cfu/ml of INA E. herbicola or 105 cfu/ml of INA P. syringae 48 hr before exposure to freezing temperatures. Populations of an INA E. herbicola isolate and a streptomycin-resistant mutant of M232A (M232ASR11) were estimated on seedlings treated with M232ASR11 at different times both before and after treatment with the INA E. herbicola. Total populations of bacteria at the time of freezing were nearly constant (~107 cfu/g fresh weight), but the fraction that was ice nucleation active decreased with increasing time of pretreatment with M232ASR11. A significant linear correlation was found between the logarithm of INA populations of E. herbicola present on leaves at the time of freezing and frost injury to those leaves. M232A significantly reduced frost injury incited by six different E. herbicola and two different P. syringae isolates.

Lindow SE; Arny DC; Upper CD

1983-08-01

312

Parámetros cuantitativos para la evaluación de la suscepti­bilidad a la erosión de suelos tropicales dominicanos Quantitative parameters for assessing susceptibility to erosion in tropical Dominican soils  

Directory of Open Access Journals (Sweden)

Full Text Available La capa superficial de los suelos de dife­rentes tipos de bosques tropicales húmedos y secos presentes en la provincia de Peder­nales (República Dominicana), ha sido eva­luada mediante diferentes parámetros rela­cionados con el proceso de erosión: tamaño de partículas, cociente limo/arcilla y un es­timador de la posibilidad de pérdida de sue-lo. Algunos de los ecosistemas más valiosos están amenazados por talas y quemas y por la implantación de cafetales, de ahí el interés y objetivo de este trabajo, para ver como es­tos usos y manejos afectan a los suelos. Los resultados se presentan comparando los pa­rámetros estudiados en 79 muestras analiza­das según las unidades paisajísticas (bos­ques con y sin usos agropascícolas), así co­mo según las litologías predominantes en las mismas: calizas cristalinas, calizas car­bonatadas sobre alteritas y calizas coralinas. El trabajo muestra por vez primera para esta región, parámetros cuantitativos respecto a procesos edáficos vinculados a la erosión en dicho territorio. Otro dato relativamente no­vedoso es el utilizar la metodología láser para los análisis del tamaño de partículas.The topsoil layers (0-20 cm) of different types of wet and dry tropical forests of the Pedernales province (Dominican Republic), both natural and cultivated, were assessed in terms of different parameters related to the erosion processes: particle size, silt/clay ra­tio, and an estimate of the possible soil loss. Some of the soils of the most valuable eco­systems are threatened by the introduction of coffee and hence the interest and objec­tive of this work. We present these data for 79 soil samples according to the corresponding landscape units (forests) along with their dominant lithologies (crystalline limestones, carbon­ated limestones on alterites and coral lime­stones). The novelty of this study is that it uses quantitative variables to describe ed­aphic processes linked to erosion in this re­gion, that had never been quantitatively studied the soils. Another relatively new fact is the methodology uses of the laser for par­ticle size analysis.

A. J. Hernández; C. Vizcayno; S. Alexis; J. Pastor

2010-01-01

313

Parámetros cuantitativos para la evaluación de la suscepti­bilidad a la erosión de suelos tropicales dominicanos/ Quantitative parameters for assessing susceptibility to erosion in tropical Dominican soils  

Scientific Electronic Library Online (English)

Full Text Available Abstract in spanish La capa superficial de los suelos de dife­rentes tipos de bosques tropicales húmedos y secos presentes en la provincia de Peder­nales (República Dominicana), ha sido eva­luada mediante diferentes parámetros rela­cionados con el proceso de erosión: tamaño de partículas, cociente limo/arcilla y un es­timador de la posibilidad de pérdida de sue-lo. Algunos de los ecosistemas más valiosos están amenazados por talas y quemas y por la implantación de cafetales, d (more) e ahí el interés y objetivo de este trabajo, para ver como es­tos usos y manejos afectan a los suelos. Los resultados se presentan comparando los pa­rámetros estudiados en 79 muestras analiza­das según las unidades paisajísticas (bos­ques con y sin usos agropascícolas), así co­mo según las litologías predominantes en las mismas: calizas cristalinas, calizas car­bonatadas sobre alteritas y calizas coralinas. El trabajo muestra por vez primera para esta región, parámetros cuantitativos respecto a procesos edáficos vinculados a la erosión en dicho territorio. Otro dato relativamente no­vedoso es el utilizar la metodología láser para los análisis del tamaño de partículas. Abstract in english The topsoil layers (0-20 cm) of different types of wet and dry tropical forests of the Pedernales province (Dominican Republic), both natural and cultivated, were assessed in terms of different parameters related to the erosion processes: particle size, silt/clay ra­tio, and an estimate of the possible soil loss. Some of the soils of the most valuable eco­systems are threatened by the introduction of coffee and hence the interest and objec­tive of this work. We present (more) these data for 79 soil samples according to the corresponding landscape units (forests) along with their dominant lithologies (crystalline limestones, carbon­ated limestones on alterites and coral lime­stones). The novelty of this study is that it uses quantitative variables to describe ed­aphic processes linked to erosion in this re­gion, that had never been quantitatively studied the soils. Another relatively new fact is the methodology uses of the laser for par­ticle size analysis.

Hernández, A. J.; Vizcayno, C.; Alexis, S.; Pastor, J.

2010-01-01

314

Adaptação de espécies arbóreas nativas em um sistema agrossilvicultural, submetidas a extremos climáticos de geada na região de Florianópolis Adaptation of native tree species submitted to extreme frost stress under an agrosilvicultural system in the Florianopolis region  

Directory of Open Access Journals (Sweden)

Full Text Available O principal objetivo deste trabalho foi avaliar a resposta de cinco espécies arbóreas nativas submetidas a extremos climáticos de geada em um sistema agroflorestal, na região de Florianópolis, Santa Catarina (latitude de 27º35' S , longitude 48º34' W e altitude de 1,84 m). O solo é do tipo Neossolo quartzarênico hidromórfico distrófico, textura arenosa, com elevada flutuação do lençol freático. Foram tomadas sete parcelas de dez árvores, seguindo o delineamento estatístico inteiramente casualizado. Os parâmetros analisados foram altura total, número de folhas, incremento médio em altura total e número de folhas de cada árvore (quantificados a cada quatro meses), porcentagem de árvores com folhas danificadas pela geada e sobrevivência de cada planta após a geada. Os parâmetros estatísticos analisados foram a média e o desvio-padrão. Para analisar os resultados utilizou-se o teste de Tukey, a 5% de probabilidade. Os ingás (Inga uruguensis e Inga sessilis) apresentaram tolerância à geada e um alto potencial para implantação em SAFs nas condições edafoclimáticas em estudo. A espécie tucaneira (Citharexylium myrianthum) apresentou pouca tolerância à geada, porém mostrou alta taxa de rebrota. As espécies corticeira (Erythrina falcata), olandi (Calophyllum brasilienses) e licurana (Hieronyma alchorneoides) apresentaram alta mortalidade em razão da geada, não se mostrando indicadas para compor um SAF na região em estudo.This work aimed to evaluate the response of five indigenous arboreal species, submitted to extreme frost stress in an agroforest system (AFS) in Florianópolis, Santa Catarina (lat. 27º35' S, long. 48º34' W and alt. of 1,84 m). The soil is a distrophic Hydromorphic Quartzarenic Neosoil, with sandy texture, and high watertable flotation.The experiment was arranged in a randomized complete design, with seven plots of ten trees each. The analyzed parameters were: height, number of leaves, average height increase and number of leaves of each tree, measured every four months, percentage of burned leaves and rate of survival of the plants after frost. The statistical parameters analyzed were: average and standard deviation.The Tukey test at 5% probability was used to analyze the results. The ingás (Inga uruguensis and Inga sessilis) showed tolerance to frost and a high potential for AFS, under the edafo-climatic conditions studied. The species tucaneira (Citharexylum myrianthum) did not show good tolerance to frost but it did show a high resprouting rate. The species corticeira (Erythrina falcata), olandi (Calophyllum brasiliense) and licurana (Hieronyma alchorneoides) showed a high mortality rate under frost, but it did not show a good potential for AFS under the edafo-climatic conditions studied.

Ana Rita Rodrigues Vieira; Diogo Feistauer; Vanderley Porfírio da Silva

2003-01-01

315

Fundamental study on melting of inclined frost layer by radiative heat energy. Netsu hosha ni yoru keisha shimoso no yukai ni kansuru kiso kenkyu  

Energy Technology Data Exchange (ETDEWEB)

This paper describes a new defrosting method in which a frost layer is melted by radiative heat energy as an energy source. The far-infrared radiative heat energy having a maximum wavelength of 5.5[mu]m was selected as the optimum radiative heat energy source for melting the inclined frost-layer. Inclined frost-layer melting experiments using the radiative heat energy with a discharge of melted water on a cooling copper plate were conducted under various environmental conditions including porosity of frost-layer as a frost structural factor. Effects of inclination angle of frost-layer, radiative heat energy flux, ambient air temperature, and initial cooling brine temperature on the frost-layer melting were examined. The frost-layer melting behavior was quantitatively made clear by the temperature profile, heat transfer, and visualization of melting. Consequently, the dimensionless correlation equations which can predict the time taken for complete frost-layer melting were derived as a function of various nondimensional frost-layer melting parameters through the dimensional analysis. 6 refs., 13 figs.

Inaba, H.; Shigemori, A. (Okayama University, Okayama (Japan). Faculty of Engineering); Otake, H. (Sanden Corp., Gunma (Japan))

1993-11-25

316

The minimum temperatures in the winter 2006/07 in the slovenian frost hollows and cold basins  

Directory of Open Access Journals (Sweden)

Full Text Available The members of Slovenian Meteorological Forum, Department of Geography at Universityof Ljubljana and Slovenian Forestry Institute started to measure temperatures in Slovenianfrost hollows and cold basins in 2004. The measurements, which improved during theperiod 2004?2006, continued also in the winter 2006?2007, all together, in more than 30frost hollows and cold basins Alpine, Dinaridic and even Submediterranean areas. Althoughthe winter 2006/2007 was very mild, minimum temperatures in frost hollow Hribarice fellbelow ? 35 ?C.

Matej Ogrin

2007-01-01

317

Comparison of heat pump performance using fin-and-tube and microchannel heat exchangers under frost conditions  

International Nuclear Information System (INIS)

Vapor compression heat pumps are drawing more attention in energy saving applications. Microchannel heat exchangers can provide higher performance via less core volume and reduce system refrigerant charge, but little is known about their performance in heat pump systems under frosting conditions. In this study, the system performance of a commercial heat pump using microchannel heat exchangers as evaporator is compared with that using conventional finned-tube heat exchangers numerically and experimentally. The microchannel and finned-tube heat pump system models used for comparison of the microchannel and finned-tube evaporator performance under frosting conditions were developed, considering the effect of maldistribution on both refrigerant and air sides. The quasi-steady-state modeling results are in reasonable agreement with the test data under frost conditions. The refrigerant-side maldistribution is found remarkable impact on the microchannel heat pump system performance under the frost conditions. Parametric study on the fan speed and the fin density under frost conditions are conducted as well to figure out the best trade-off in the design of frost tolerant evaporators. (author)

2002-01-00

318

Analysis of heat transfer and frost layer formation on a cryogenic tank wall exposed to the humid atmospheric air  

International Nuclear Information System (INIS)

In this paper heat transfer characteristics and frost layer formation are investigated numerically on the surface of a cryogenic oxidizer tank for a liquid propulsion rocket, where a frost layer could be a significant factor in maintaining oxidizer temperature within a required range. Frost formation is modeled by considering mass diffusion of water vapor in the air into the frost layer and various heat transfer modes such as natural and forced convection, latent heat, solar radiation of short wavelength, and ambient radiation of long wavelength. Computational results are first compared with the available measurements and show favorable agreement on thickness and effective thermal conductivity of the frost layer. In the case of the cryogenic tank, a series of parametric studies is presented in order to examine the effects of important parameters such as temperature and wind speed of ambient air, air humidity, and tank wall temperature on the frost layer formation and the amount of heat transfer into the tank. It is found that the heat transfer by solar radiation is significant and also that heat transfer strongly depends on air humidity, ambient air temperature, and wind speed but not tank wall temperature.

2009-01-01

319

Effects of climatic warming on northern trees: Testing the frost damage hypothesis with meteorological data from provenance transfer experiments  

Energy Technology Data Exchange (ETDEWEB)

According the a hypothesis presented recently the predicted climatic warming will cause premature bud burst of trees in Finnish conditions during mild spells in mid-winter and heavy frost damage during subsequent periods of frost. The full stocking and high productivity of northern Finnish provenances of Picea abies (L.) Karst. grown in central and southern Finland for several decades seemed to conflict with the frost damage hypothesis, because the increase in the annual mean temperature involved in the most distant provenance transfers exceeded the predicted increase in the annual mean temperature in northern Finland. A calculation method using air temperature data from provenance transfer experiments was developed for testing the frost damage hypothesis. The method was applied with temperature data from Finnish provenance transfer experiments, assuming for northern Finland both (1) a uniform warming scenario of 4.7 deg C throughout the year and (2) a non-uniform warming scenario in which the same mean annual temperature increase is applied more to winter than to summer. The results revealed that the present air temperature conditions in central and southern Finland do not correspond to those of either of the scenario climates in northern Finland; thus the frost damage hypothesis was not falsified. The calculation method developed can be used in testing the frost damage hypothesis in the case of other tree species, locations and warming scenarios by altering the specifications applied in the method. 32 refs, 3 figs, 2 tabs

Haenninen, H. [Joensuu Univ. (Finland). Faculty of Forestry

1996-05-01

320

Heat transfer and frost growth on a wind convector based on a row of vertical cylindrical tubes  

Energy Technology Data Exchange (ETDEWEB)

A wind convector is an alternative outdoor heat exchanger for air-source heat pumps which allows transfer of heat from the outdoor environment to an antifreeze solution (brine) without the use of a fan to move the outdoor air across the heat-exchange surfaces. The objectives of this study are to: (a) experimentally investigate the effects of weather conditions on the overall heat transfer coefficient for and frost growth on a wind convector based on a row of vertical cylindrical tubes placed outdoors; and (b) mathematically model the frost growth and heat transfer through the frost layer. An automatically-controlled, microcomputer-monitored outdoor test facility capable of continuous measurement of overall wind-convector heat transfer coefficient, U, to within a measurement uncertainty of {plus minus}3% was built and tested. At the site the following weather conditions are measured: air temperature and humidity, wind speed and direction, solar radiation and rainfall. Frost depth is measured by a computer vision system and frost mass is measured with a weighing cell. Tests of up to 24 hours duration in the unsteady outdoor environment were carried out. Mathematical models of the diffusion-dominated and meltback regimes of frost growth on circular cylinders were developed and compared to experimental measurements.

Monaghan, P.F.

1989-01-01

 
 
 
 
321

Calculation and Analysis of Frost Duration Times by Using Delphi Programming: A Case Study in Lorestan, Iran  

Directory of Open Access Journals (Sweden)

Full Text Available The purpose of the present study is to calculate the duration times of frosts by Delphi programming. To do this, the data related to the daily minimum temperature of four meteorology stations of Lorestan Province, i.e., Khoram-Abad, Boroujerd, Doroud and Aligoudarz that enjoy a ten-year statistics (from 1993 to 2003) were obtained from the information bank of the National Meteorology Organization. After taking out the frost days in desired threshold (zero and less than zero) during the statistical period, frost duration times of each station were calculated and extracted, using algorithm of the afore-mentioned program. Then, the duration times were selectively divided into eight (three-hour) classes. Their frequency percent charts were drawn and all stations were compared to one another in three classes of 0 to 3 h, 9 to 12 h and 21 to 24 h. It was concluded that Boroujerd Station enjoys the most frost hours and, hence damages to crops were the highest in this station compared with other stations. It was further concluded that the vegetation is the most effective factor in frost duration times of the region and that the height factor has no effect on frost duration times.

Z. Hejazizadeh; M.H. Naserzadeh

2007-01-01

322

Fall frost resistance in willows used for biomass production. II. Predictive relationships with sugar concentration and dry matter content.  

UK PubMed Central (United Kingdom)

The accumulation of sugars and dry matter in stems in fall was examined in relation to frost hardening in eight willow clones (six clones of Salix viminalis L. and one clone each of S. viminalis x S. schwerenii E. Wolf and S. dasyclados Wimm.). Evidence is presented that three sources of variation in fall frost resistance among the eight clones could be assessed from an analysis of stem composition. First, the pre-hardening value of frost resistance could be assessed from the total sugar concentration. Second, the start of induction of apical growth cessation and hence frost hardening could be distinguished by a stepwise increase in sucrose-to-glucose ratio. Third, the progress of frost hardening during its first phase could be followed from a proportional rise in total sugar concentration and, even more accurately, from a proportional rise in dry-to-fresh weight ratio. In contrast, the second phase of frost hardening was largely uncoupled from sugar and dry matter accumulation. Raffinose and sucrose accumulation seemed to be under differential environmental controls. Sucrose accumulation started with the initiation of growth cessation controlled by photoperiod, whereas raffinose accumulation started with falling temperatures later on. Starch reserves that built up in stems in early fall were partially mobilized later on to support sugar accumulation. In contrast to stems, leaves did not exhibit a preferential accumulation of sucrose in fall.

Ogren E

1999-09-01

323

The potential importance of frost flowers, recycling on snow, and open leads for ozone depletion events  

Directory of Open Access Journals (Sweden)

Full Text Available We present model studies with the one-dimensional model MISTRA to investigate the potential role of frost flowers, recycling on snow, and open leads in the depletion of tropospheric ozone in the Arctic spring. In our model, we assumed frost flower aerosols to be the major source of bromine. We show that a major ozone depletion event can be satisfactorily reproduced only if the recycling on snow of deposited bromine into gas phase bromine is assumed. In the model, this cycling is more efficient than the bromine explosion process and maintains sufficiently high levels of bromine to deplete ozone down to few nmol mol?1 within four days. We assessed the influence of different surface combinations (open lead/frost flowers) on the chemistry in the model. Results showed noticeable modifications affecting the composition of aerosols and the deposition velocities. A model run with a series of coupled frost flower fields and open leads, separated by large areas of snow, showed results comparable with field observations. In addition, we studied the effects of modified temperature of either the frost flower field or the ambient airmass. A warmer frost flower field increases the relative humidity and the aerosol deposition rate. The deposition/re-emission process gains in importance, inducing more reactive bromine in the gas phase, and a stronger ozone depletion. A decrease of 1K in airmass temperature shows in our model that the aerosol uptake capacities of all gas phase species substantially increases, leading to enhanced uptake of acids from the gas phase. Consequently, the so-called bromine explosion accelerated and O3 mixing ratios decreased. In our model representation, variations in wind speed affected the aerosol source function and influenced the amount of bromine in the atmosphere and thus the ozone depletion strength. Recent studies have suggested the important role of the precipitation of calcium carbonate (CaCO3) out of the brine layer for the possible acidification of the liquid phase by acid uptake. Our investigation showed that this precipitation is a crucial process for the timing of the bromine explosion in aerosols. Nevertheless, model runs with either 50% precipitation or complete precipitation displayed a relatively weak difference in ozone mixing ratios after four simulated days. By considering conditions typical for "Arctic Haze" pollution events at the start of the run we obtained a low pH in frost flower aerosols due to a greater mixing ratio of SO2, and a strong recycling efficiency via large aerosol number concentration. The aerosol acidification during a haze event most likely intensifies the ozone depletion strength and occurrence. The comparison between our modeled deposition on snow and sampled snow at Barrow (Alaska) shows that approximately 75% of deposited bromine may be re-emitted into the gas phase as Br2/BrCl. Among several non-halogen fluxes from the snow, model simulations showed that only HONO affects the chemistry. Finally, we investigated the release of Br2 potentially produced by heterogeneous reactions directly on frost flowers. In this case, we obtained unrealistic results of aerosol compositions and deposition rates on snow compared to observations in the Arctic.

M. Piot; R. von Glasow

2008-01-01

324

The potential importance of frost flowers, recycling on snow, and open leads for Ozone Depletion Events  

Directory of Open Access Journals (Sweden)

Full Text Available We present model studies with the one-dimensional model MISTRA to investigate the potential role of frost flowers, recycling on snow, and open leads in the depletion of tropospheric ozone in the Arctic spring. In our model, we assumed frost flower aerosols to be the major source of bromine. We show that a major ozone depletion event can be satisfactorily reproduced only if the recycling on snow of deposited bromine into gas phase bromine is assumed. In the model, this cycling is more efficient than the bromine explosion process and maintains sufficiently high levels of bromine to deplete ozone down to few nmol mol?1 within four days. We assessed the influence of different surface combinations (open lead/frost flowers) on the chemistry in the model. Results showed noticeable modifications affecting the composition of aerosols and the deposition velocities. A model run with a series of coupled frost flower fields and open leads, separated by large areas of snow, showed results comparable with field observations. In addition, we studied the effects of modified temperature of either the frost flower field or the ambient airmass. A warmer frost flower field increases the relative humidity and the aerosol deposition rate. The deposition/re-emission process gains in importance, inducing more reactive bromine in the gas phase, and a stronger ozone depletion. A decrease of 1 K in airmass temperature shows in our model that the aerosol uptake capacities of all gas phase species substantially increases, leading to enhanced uptake of acids from the gas phase. Consequently, the so-called bromine explosion accelerated and O3 mixing ratios decreased. In our model representation, variations in wind speed affected the aerosol source function and influenced the amount of bromine in the atmosphere and thus the ozone depletion strength. Recent studies have suggested the important role of the precipitation of calcium carbonate (CaCO3) out of the brine layer for the possible acidification of the liquid phase by acid uptake. Our investigation showed that this precipitation is a crucial process for the timing of the bromine explosion in aerosols. Nevertheless, model runs with either 50% precipitation or complete precipitation displayed a relatively weak difference in ozone mixing ratios after four simulated days. By considering conditions typical for "Arctic Haze" pollution events at the start of the run we obtained a low pH in frost flower aerosols due to a greater mixing ratio of SO2, and a strong recycling efficiency via large aerosol number concentration. The aerosol acidification during a haze event most likely intensifies the ozone depletion strength and occurrence. The comparison between our modeled deposition on snow and sampled snow at Barrow (Alaska) shows that approximately 75% of deposited bromine may be re-emitted into the gas phase as Br2/BrCl. Among several non-halogen fluxes from the snow, model simulations showed that only HONO affects the chemistry. Finally, we investigated the release of Br2 potentially produced by heterogeneous reactions directly on frost flowers. In this case, we obtained unrealistic results of aerosol compositions and deposition rates on snow compared to observations in the Arctic.

M. Piot; R. von Glasow

2007-01-01

325

Influence of supermarket environmental parameters on the frosting and defrosting of vertical multideck display cabinets  

Energy Technology Data Exchange (ETDEWEB)

This paper reports on results of investigations to identify and quantify the effect of in-store environmental conditions on frost accumulation on the evaporator coils of open multideck refrigerated display cabinets. Field and environmental chamber-based tests have shown that both ambient relative humidity and temperature of a store have a significant effect on the rate of frost formation on the evaporator coils, with the effect of relative humidity being much more pronounced than the effect of temperature. In supermarkets where a fixed-time defrost control strategy is employed, it is possible that cabinets are defrosted too infrequently at high relative humidities, resulting in high product temperatures, and too frequently at low relative humidities, resulting in excessive energy consumption. Considerable opportunity exists for the application of more sophisticated defrost control strategies, both to save energy and improve temperature control.

Tassou, S.A.; Datta, D.

1999-07-01

326

Technique for cultivating virus-free frost-resisting sapling of teak  

UK PubMed Central (United Kingdom)

The invention provides a technique for cultivating the virus-free frost-resisting sapling of teak (Tectona grandis). The technique comprises the following steps that: collecting seeds from the selected Northern Burma native teak having big difference in temperature carrying out primary acclimation on the cultivated sapling (15cm to 20cm) of teak through artificial temperature control in a temperature-controllable greenhouse shipping the acclimated sapling to a growing area, stumping the sapling and further carrying out regional-adaptability secondary acclimation and removing mud from the acclimated sapling, cutting the root and carrying out the virus-eliminating treatment in a virus eliminating room to obtain the frost-resisting high-yield fast-growing sapling. The technique is suitable for the transplant and growth of other tropical and subtropical saplings to different places.

ZUWEN YANG

327

Air void structure and frost resistance : A challenge to Powers’ spacing factor  

DEFF Research Database (Denmark)

This article compiles results from 4 independent laboratory studies. In each study, the same type of concrete is tested at least 10 times, the air void structure being the only variable. For each concrete mix both air void analysis of the hardened concrete and a salt frost scaling test are conducted. Results were not originally presented in a way, which made comparison possible. Here the amount of scaled material is depicted as function of air voids parameters: total air content, specific surface, spacing factor, and total surface area of air voids. The total surface area of air voids is proportional to the product of total air content and specific surface. In all 4 cases, the conclusion is concurrent that the parameter of total surface area of air voids performs equally well or better than the spacing factor when linking air void characteristics to frost resistance (salt frost scaling). This observation is interesting as the parameter of total surface area of air voids normally is not included in air void analysis. The following reason for the finding is suggested: In the air voids conditions are favourable for ice nucleation. When a capillary pore is connected to an air void, ice formation will take place in the air void, being feed from the capillary, but without pressure build-up in the capillary. If the capillary is not connected to an air void, ice formation will take place in the capillary pore, where it can generate substantial pressure. Like this, frost resistance depends on that capillary pores are connected to air voids. The chance that a capillary pore is connected to an air void depends on the total surface area of air voids in the system, not the spacing factor.

Hasholt, Marianne Tange

2013-01-01

328

Effects of frost on wildflowers: an unexpected consequence of climate change--image 11 of 22  

Science.gov (United States)

Results of a demographic study of Helianthella quinquenervis (aspen sunflower, Asteraceae) within plots at 2,900m at the Rocky Mountain Biological Laboratory. Note that seedlings are not common in most years, and the overall population seems to be declining. The lack of seedlings in most years is a consequence of frost damage to flower buds the previous year (so no seeds were produced). The population decline is an apparent consequence of reduced seed production.

Inouye, David

2012-01-04

329

Simulación del depósito de Escarcha en superficies frías/ Simulation of Frost Deposit in Cold Surfaces  

Scientific Electronic Library Online (English)

Full Text Available Abstract in spanish Se presenta un código computacional que simula la formación y crecimiento de escarcha sobre una placa mantenida a baja temperatura, por ablimación del vapor de agua de una corriente de aire húmedo que fluye sobre ella. La modelación se basa en ecuaciones de conservación de masa, energía, cantidad de movimiento y especies aplicadas a la escarcha, mezcla aire-vapor e interfase aire-escarcha. El sistema de ecuaciones resulta no lineal acoplado por la fracción volumé (more) trica del hielo, que es calculada iterativamente. El modelo es validado frente a datos experimentales, permitiendo reproducir la evolución de propiedades termofísicas de la escarcha formada y predecir comportamientos para otras condiciones de operación. Los resultados revelan mejor concordancia con datos experimentales que la obtenida por otros autores, y levemente inferior a la del modelo de sobresaturación. Abstract in english The development of a computational code that simulates the formation and frost growth on a cool plate, for the vapor-water ablimation of a humid air current that flows on it, is presented. The numeric modeling is based on the conservation equations of mass, energy, momentum and species applied to the frost, air-vapor mixtures and air-frost interface. The system of equations is not linear and is coupled by the ice volumetric fraction which is calculated by iteration. The m (more) odel is validated by comparing the numerical results with experimental data, reproducing the thermophysical properties evolution of the frost formed and predicting the behavior for other operating conditions. The results reveal better agreement with experimental data that those obtained by other authors, and slightly inferior to that of the supersaturation model.

Gatica, Jorge A; Pita, Vicente A; Lobo, Nisio de C

2009-01-01

330

Multitype randomized Reed--Frost epidemics and epidemics upon random graphs  

CERN Multimedia

We consider a multitype epidemic model which is a natural extension of the randomized Reed--Frost epidemic model. The main result is the derivation of an asymptotic Gaussian limit theorem for the final size of the epidemic. The method of proof is simpler, and more direct, than is used for similar results elsewhere in the epidemics literature. In particular, the results are specialized to epidemics upon extensions of the Bernoulli random graph.

Neal, P

2006-01-01

331

Simulación del depósito de Escarcha en superficies frías Simulation of Frost Deposit in Cold Surfaces  

Directory of Open Access Journals (Sweden)

Full Text Available Se presenta un código computacional que simula la formación y crecimiento de escarcha sobre una placa mantenida a baja temperatura, por ablimación del vapor de agua de una corriente de aire húmedo que fluye sobre ella. La modelación se basa en ecuaciones de conservación de masa, energía, cantidad de movimiento y especies aplicadas a la escarcha, mezcla aire-vapor e interfase aire-escarcha. El sistema de ecuaciones resulta no lineal acoplado por la fracción volumétrica del hielo, que es calculada iterativamente. El modelo es validado frente a datos experimentales, permitiendo reproducir la evolución de propiedades termofísicas de la escarcha formada y predecir comportamientos para otras condiciones de operación. Los resultados revelan mejor concordancia con datos experimentales que la obtenida por otros autores, y levemente inferior a la del modelo de sobresaturación.The development of a computational code that simulates the formation and frost growth on a cool plate, for the vapor-water ablimation of a humid air current that flows on it, is presented. The numeric modeling is based on the conservation equations of mass, energy, momentum and species applied to the frost, air-vapor mixtures and air-frost interface. The system of equations is not linear and is coupled by the ice volumetric fraction which is calculated by iteration. The model is validated by comparing the numerical results with experimental data, reproducing the thermophysical properties evolution of the frost formed and predicting the behavior for other operating conditions. The results reveal better agreement with experimental data that those obtained by other authors, and slightly inferior to that of the supersaturation model.

Jorge A Gatica; Vicente A Pita; Nisio de C Lobo

2009-01-01

332

Effects of frost on wildflowers: an unexpected consequence of climate change--image 02 of 22  

Science.gov (United States)

An example of a late spring frost and snow event at the Rocky Mountain Biological Laboratory, at 9,500 feet in the Colorado Rocky Mountains. This photograph was taken on 13 June 2001, when the temperature went down to 21.5 F, (-5.8 C). This cold period killed flower buds of several wildflower species that had already produced leaves and buds.

Inouye, David

2012-01-04

333

Effects of frost on wildflowers: an unexpected consequence of climate change--image 21 of 22  

Science.gov (United States)

A graph (modified from Boggs and Inouye 2012, Ecology Letters) demonstrating that Speyeria mormonia (Mormon fritillary) butterfly visits are proportionally greater when their food plant, Erigeron (fleabane), produces many flowers. Frost damage reduces the number of available flowers. When flowers are abundant, they produce more nectar and attract more butterflies. In turn, the greater availability of nectar causes the fritillary butterfly to produce more eggs.

Inouye, David

2012-02-28

334

Effects of frost on wildflowers: an unexpected consequence of climate change--image 17 of 22  

Science.gov (United States)

The glacier lily (Erythronium grandiflorum) is one of the earliest wildflowers to bloom after snowmelt in the Rocky Mountains. Its ovaries and seeds are sensitive to late-season frosts. But because the species is a perennial, it can survive occasional years of reproductive failure by blooming the following year. By avoiding the cost of producing the relatively large fruit and seeds in one year, the plant may have better survivorship and be able to produce more flowers the next year.

Inouye, David

2012-01-04

335

Frost formation and defrost control parameters for open multideck refrigerated food display cabinets  

Energy Technology Data Exchange (ETDEWEB)

In order to achieve the required air and product temperatures in refrigerated food display cabinets, the evaporator coils, which are normally located in the base of the cabinets, operate at temperatures below the freezing point of water. The air which is circulated over the evaporator coil is cooled below its dew point and water vapour present in the air condenses and eventually freezes on the coil surface. With continuous operation of the coil, frost will accumulate on the coil surface leading to a decrease both in the air flowrate and in the overall heat transfer coefficient. In order to maintain satisfactory performance, evaporator coils are defrosted periodically. Although different defrost control strategies can be employed, for simplicity and cost considerations, defrosting in supermarket refrigeration systems is usually controlled by a pre-set time cycle. It is widely acknowledge, however, that time-based defrost may cause a number of unnecessary defrost cycles and this reduces the energy efficiency of the refrigeration systems as well as the accuracy of temperature control of the cabinets. Implementing defrost only when it is needed or on 'demand' should reduce the number of defrost cycles and lead to savings in energy and improved product quality. This paper reports on field and experimental investigations on the processes of frosting and defrosting of medium-temperature display cabinet evaporator coils. The results show that for medium-temperature refrigeration applications where the environment temperature is kept reasonably constant, the store humidity is the primary parameter influencing the rate of frost formation. Using relative humidity as a control parameter the defrost frequency can be reduced considerably without affecting cabinet performance and product integrity. Alongside the effect of relative humidity, the paper also considers the effects of other performance parameters on the processes of frosting and defrosting such as cooling time and length of previous defrost cycle, and discusses ways in which some of these parameters may be used to implement defrost on demand. (Author)

Tassou, S.A.; Datta, D. [Brunel Univ., Dept. of Mechanical Engineering, Uxbridge (United Kingdom); Marriott, D. [Safeway Stores plc, Hayes (United Kingdom)

2001-04-03

336

Erodibilidade e suscetibilidade à erosão dos solos de cerrado com plantio de Acacia mangium em Roraima.= Erodibility and susceptibility to erosion of the savannah (cerrado) soils planted with Acacia mangium in the State of Roraima.  

Directory of Open Access Journals (Sweden)

Full Text Available Com o objetivo de avaliar erodibilidade e suscetibilidade à erosão de solos sob cerrados e plantios de Acácia mangium no estado de Roraima, foram realizadas visitas nas áreas objeto de estudo para identifi cação geomorfopedológica e feito coleta de solo representativo de 121 perfi s distribuídos nas áreas de plantio de Acacia mangium pertencentes ao projeto Ouro Verde Agrosilvopastoril Ltda. Os perfi s descritos e coletados foram georreferenciados através de GPS e plotados sobre mapas de declividades no software ARCMAPE 8.0 permitindo cruzar os valores de R com a declividade. Foi avaliada as relações do tipo de solo, sua posição na paisagem e suscetibilidade a erosão. Os resultados revelaram que as áreas de estudo estão inseridas em duas unidades geomorfopedológicas distintas: Jacitara/Mucajaí/Santa Cecília (JMSta) e Serra da Lua (SL), apresentando suscetibilidade à erosão bem contrastantes; As unidades JMSta apresentam maiores valores de R, inseridas em relevo plano, com declividade entre 1% a 3%, os solos da unidade SL, apresentam menores valores de R e estão posicionados em relevo com declividade entre 3 a 13%, o que a torna mais vulneráveis a erosão; as classes de solos em ordem decrescente em valores de R são: Neossolos (RQo), Argissolos (PAd), Gleissolos (GXbd), Latossolos (LAd, LVd, LVAd, LVA Plintico), Plintossolos (FFCd), concluindo-se então, a necessidade da adoção de práticas simples de conservação de solos, tais como plantio em curva de nível e até terraceamento. = With the objective to evaluate the erodibility and susceptibility to erosion of the cerrado and plantations with Acacia mangium in the State of Roraima, visits to the areas were done for geomorfopedologic identifi cation and collection of soils representative of 121 profi les distributed in the areas pertaining to the plantation of Acacia mangium of the Ouro Verde Agrosilvopastoril Ltda project. The described and collected profiles were geo-referenced through GPS and located on maps of declivities by the software ARCMAPE 8,0 allowing to cross the values of R with the declivity. There were evaluate the relations of the type of soils, its position in the landscape and susceptibility the erosion. The results obtained indicated that the areas studiedy are inserted in two distinct geomorphopedologic units: Jacitara/Mucajai/Santa Cecilia (JMSta) and Serra da Lua (SL), and demonstrated distinct susceptibility to erosion; The JMSta units presented the most elevated values of R, inserted in plain relief, with declivity between 1% and 3%. The ground of unit SL, presented small values of R and is located in terrain with declivity between 3% and 13%, which becomes it more vulnerable to erosion; The types of soils decreasing order of values of R are: Neossolos (RQo), Argissolos (PAd), Gleissolos (GXbd), Latossolos (LAd, LVd, LVAd, LVA Plintico), Plintossolos (FFCd). In conclusion, there is the necessity to adopt simple practices of ground conservation, varying from plantation on the curve of level to terracing.

José Frutuoso do Vale Júnior; Luciana da Silva Barros; Maria Ivonilde Leitão de Sousa; Sandra Catia Pereira Uchôa

2009-01-01

337

EVALUATION OF FROST INCIDENCE IN SOME COMPONENTS OF CORN PRODUCTIVITY (Zea mays L.)  

Directory of Open Access Journals (Sweden)

Full Text Available With the objective of evaluating the effects of the July 13th to 17th, 2.000 frosts on the production components and on the total protein content in the corn grains, reached by different growth stages, two studies were carried out in Picadinha District, in Dourados, Mato Grosso do Sul. Data were obtained and analyzed considering a complete randomized experimental design, with treatments arranged in 3x5 factorial scheme, corresponding to three places with five collecting per place, resulting in 15 treatments with 4 replications, for the Tork hybrid; whereas for the C 901 hybrid, treatments were arranged in a 2x5 factorial scheme, which corresponded to two locations with five sampling times, resulting in 10 treatments with 4 replications. For comparison among averages, the Duncan test at 5% probability was used. To evaluate the effect of collection periods, the model of polynomial regression was used and it was concluded that plants affected by frosts accumulated dry matter in grains until they reached physiology maturity. Accumulation of dry matter in grains is directly proportional to the damages caused in the leaf area of plants and to the development of grains during frost periods.

ANGELO CESAR AJALA XIMENES; LUIZ CARLOS FERREIRA DE SOUZA; ANTÔNIO DIAS ROBAINA; MANOEL CARLOS GONÇALVES

2004-01-01

338

Effects of frost on wildflowers: an unexpected consequence of climate change--image 10 of 22  

Science.gov (United States)

The number of flowers produced by the aspen sunflower (Helianthella quinquenervis) in a particular year is affected by the date of the start of the growing season, which is in turn influenced by the date that the winter snowpack melts. Years with low winter snowfall and warm springs have more rapid snowmelt and an earlier start to the growing season than years with a heavy snowpack or a cool spring. But each year, the last hard frost occurs in early - mid June, regardless of the snowmelt date.In years having an early start to the growing season (shown in blue), aspen sunflower plants had relatively few unfrosted flowers. In such years, the early snowmelt allows plants to start their growth early. They develop many buds that are filled by the late season frost. Thus, plants produce few flowers in those years.In years having a late start to the growing season (shown in red), aspen sunflower plants had many unfrosted flowers. In those years, the late snowmelt delayed the growth of plants. Thus, frost events in June had little impact on flower production because the plants had not produced buds by that time.As seen in Image 09, years of early snowmelt have been especially common in the past decade. Thus, plant populations have experienced poorer reproductive success than in previous decades.

Inouye, David

2012-01-04

339

Five second helium neutral beam injection using argon-frost cryopumping techniques  

International Nuclear Information System (INIS)

High power helium neutral beams for the heating of tokamak discharges can now be provided for 5 s by using argon cryopumping (of the helium gas) in the beamlines. The DIII-D neutral beam system has routinely provided up to 20 MW of deuterium neutral beam heating in support of experiments on the DIII-D tokamak. Operation of neutral beams with helium has historically presented a problem in that pulse lengths have been limited to 500 ms due to reliance solely on volume pumping of the helium gas. Helium is not condensed on the cryopanels. A system has now been installed to deposit a layer of argon frost on the DIII-D neutral beam cryopanels, between tokamak injection pulses. The layer serves to trap helium on the cryopanels providing sufficient pumping speed for 5 s helium beam extraction. The argon frosting hardware is now present on two of four DIII-D neutral beamlines, allowing injection of up to 6 MW of helium neutral beams per discharge, with pulse lengths of up to 5 s. The argon frosting system is described, along with experimental results demonstrating its effectiveness as a method of economically extending the capabilities of cryogenic pumping panels to allow multi-second helium neutral beam injection

1995-01-01

340

Frost formation and defrosting of tube array evaporators in a fluidized bed and an impinging jet  

Energy Technology Data Exchange (ETDEWEB)

Using a slit string distribution plate for generating a impinging jet in each tube array in a fluidized bed, a very shallow fluidized bed which, despite a very low static bed, can produce stable fluidization and features a very small pressure loss was developed. Results of frost formation heat transfer experiments are as follows. The average Nusselt number of one string cooling tube array is two to four times better than that obtained in a heating experiment conducted in a constant single-phase air flow, and this fluidized bed (average particle diameter is 0.92 mm) using the slit string distribution plate has a minimum fluidized velocity of as well as 0.5 when compared with the value obtained by the experimental formula for a normal perforated distribution plate. The average Nusselt number of one string cooling tube array used in the experiment is five times better than that of the heat experimental result obtained in a constant single phase air flow. The average heat transfer rate of the cooling tube array in the fluidized bed does not vary with the methanol inlet temperature. Furthermore, the effect of free velocity and surface heat flow bundle outside of the tube on frost formation area rate was clarified, and it is now possible to set an area where no frosting occurs. (9 figs, 1 tab, 11 refs)

Aihara, Toshio; Gakumasawa, Hidetaka; Maruyama, Shigenao; Hongo, Mitsuo

1988-07-25

 
 
 
 
341

Numerical heat transfer model for frost protection of citrus fruits by water from a spraying system  

Directory of Open Access Journals (Sweden)

Full Text Available A simplified model is developed to simulate the conditions associated with the protection of fruits from frost damage using water from a spraying system. The model simulates the movement of the solidifying water front on a single fruit, and based on that determines the spray frequency needed for a water film to continuously surround the ice-coated fruit to prevent the fruit temperature from dropping below 0ºC. Simulations are presented for the frost protection of sweet oranges (citrus sinensis). The effect of environmental conditions such as air temperature, air velocity, surface radiation and water film evaporation on the development of the ice layer encasing is considered. Simulations show the effect the encasing ice sheet thickness has on the fruit temperature if water from a spraying system is turned off permanently. Experimental tests are also conducted to determine the change in the thermal properties of citrus sinensis for operating temperatures that range from above freezing to sub-freezing. The results of the experimental tests and the numerical simulations shall lead to a better understanding of fruit protection from frost damage by the application of water from a spraying system.

Issa Roy J.

2012-01-01

342

Carbohydrate metabolism and fruit quality are affected in frost-exposed Valencia orange fruit  

UK PubMed Central (United Kingdom)

Exposure of citrus fruit to frost often results in the development of freeze injury during their maturation in planta. This work was aimed to analyze changes in the biochemistry and enzymology of carbohydrate metabolism in freeze-injured orange fruit (Citrus sinensis var. Valencia late) and the involvement of oxidative stress in frost damage. The activities of pyrophosphate-dependent phosphofructokinase, phosphoenolpyruvate carboxylase and several fermentative enzymes increased in frost-exposed (FE) fruit, while NADP-malic enzyme and the mitochondrial isoform of NAD-malate dehydrogenase showed a reduction in their activities. Western blot analysis indicated a correlation between activity levels and protein content. Respiration rate in whole fruit was reduced by 40%, whereas the flavedo showed a more pronounced decline (53%). Volatile compound (i.e. ethanol and acetaldehyde) content was significantly higher in FE fruit than in control, as was that of [smallcapital l]-malate (three-fold). Additionally, FE fruit showed a marked decrease in the maturity index (24%) because of a higher titratable acidity (39%). Evidence is presented that oxidative stress is involved in freeze-induced damage of orange fruit, where oxidative damage to lipids and proteins, and a greater electrolyte leakage in the flavedo were also observed. The results suggest that freezing temperatures provoke a notable metabolic switch in citrus fruit toward a fermentative stage, resulting in low-quality fruits.

Falcone Ferreyra ML; Perotti V; Figueroa CM; Garrán S; Anderson PC; Vázquez D; Iglesias AA; Podestá FE

2006-10-01

343

Numerical simulation of moisture migration depending on the rate of soil freezing  

Directory of Open Access Journals (Sweden)

Full Text Available One of the geomechanics challenges is the quantitative assessment of deformation of soils associated with frost heaving and thawing. The main difficulty in solving this problem is the need to consider changing the state of soil freezing and thawing ground and thermophysical characteristics of the medium in a transient state. The main process in frozen soil is the redistribution of moisture in them due to water migration during freezing. When water freezes, the soil characteristics, its physical and mechanical properties change.This paper includes description of a numerical simulation method and study about humidity changing in frozen soils, depending on the rate of soil freezing. The influence of soil humidity changing on the values of strength characteristics during the process of thawing is evaluated.The developed technique of numerical simulation of the freezing and thawing process allows assessing the impact of frost heaving forces, decreasing the strength of buildings foundations and structures during freezing and thawing at the design stage. This allows the effective implementing of modern structures for soils and foundations reinforcement using geosynthetics to reduce or eliminate frost heave processes and thawing.

S.A. Kudryavtsev; A.V. Kazharskiy

2012-01-01

344

Aclimatação ao frio e dano por geada em canola Acclimatization to cold and frost-injury in canola  

Directory of Open Access Journals (Sweden)

Full Text Available O objetivo deste trabalho foi avaliar a influência da aclimatação ao frio sobre o dano causado pela geada em diferentes estádios fenológicos de genótipos de canola. Foram realizados cinco experimentos em ambiente controlado, em 2006, 2007 e 2008. Os fatores avaliados foram: genótipos, aclimatação (com; sem), intensidades de geada, estádios de desenvolvimento de plantas, regimes de aclimatação e regimes de geada. As variáveis avaliadas foram: queima de folhas, massa de matéria seca, estatura de plantas, duração de subperíodo, componentes de rendimento e rendimento de grãos. A aclimatação ao frio, antes da geada, resultou em menor queima de folhas e maior massa de matéria seca, em comparação a plantas não aclimatadas. As geadas foram prejudiciais a partir de -6°C no início do ciclo de desenvolvimento, principalmente em plantas não aclimatadas, e a partir de -4ºC na floração, com redução do número de síliquas e do número de grãos por síliqua. A aclimatação após as geadas não contribuiu para a tolerância da canola a esse evento. Geadas consecutivas não acarretaram maior prejuízo à canola. A aclimatação de plantas de canola antes da geada reduz os danos, principalmente quando a geada ocorre no início do desenvolvimento das plantas.The objective of this work was to evaluate the influence of cold acclimatization on frost damage at different phenological stages of canola genotypes. Five experiments were carried out under controlled conditions, in 2006, 2007, and 2008. The evaluated factors were: genotypes, acclimatization (with; without), frost gradient, plant developmental stages, acclimatization regimes and frost regimes. The evaluated variables were: leaf scorching symptoms, dry weight, plant height, length of subperiod, yield components and grain yield. The acclimatization before frost resulted in lesser leaf scorching symptoms and higher dry matter in comparison to plants not acclimated. Frosts were harmful from -6°C in early plant development stage, mainly in nonacclimated plants, and from -4ºC at flowering, reducing the number of pods and the number of grains per pod. Acclimatization after frost did not contribute to the tolerance of canola to frost. Consecutive frosts caused no greater impairment to canola. The canola acclimatization before frost reduces damage caused by it, mainly when the frost occur in the initial plant development stages.

Genei Antonio Dalmago; Gilberto Rocca da Cunha; Anderson Santi; João Leonardo Fernandes Pires; Alexandre Luiz Müller; Laise Maria Bolis

2010-01-01

345

Electoral Susceptibility  

CERN Document Server

In the United States electoral system, a candidate is elected indirectly by winning a majority of electoral votes cast by individual states, the election usually being decided by the votes cast by a small number of "swing states" where the two candidates historically have roughly equal probabilities of winning. The effective value of a swing state in deciding the election is determined not only by the number of its electoral votes but by the frequency of its appearance in the set of winning partitions of the electoral college. Since the electoral vote values of swing states are not identical, the presence or absence of a state in a winning partition is generally correlated with the frequency of appearance of other states and, hence, their effective values. We quantify the effective value of states by an {\\sl electoral susceptibility}, $\\chi_j$, the variation of the winning probability with the "cost" of changing the probability of winning state $j$. We study $\\chi_j$ for realistic data accumulated for the 201...

Levine, G C; Cerise, J E

2012-01-01

346

Interaction between cold night skies, frost occurrence and seasonal growth: A coupling between atmospheric temperature and plant ecology  

Energy Technology Data Exchange (ETDEWEB)

The occurrence of nighttime frost is important to the ecophysiology and seasonal growth of alpine/subalpine plants. Frost episodes can be the direct result of the net loss of longwave energy from the leaf to the cold night sky, even when ambient air temperatures are above freezing. This microclimate scenario may be particularly characteristic of the last spring frosts and the first fall frosts, a primary determinant of the length of the seasonal growth period. Using a leaf energy-balance approach, we found that low upper-hemisphere infrared radiation can reduce nighttime leaf temperature (T[sub L]) up to 6[degrees]C below air temperature. Furthermore, this depression in T[sub L] resulted in a substantial increase in the frequency and duration of frost events, and an ultimate shortening of the seasonal growth period of over 30%. However, the seasonal effect on vegetative growth and reproductive effort depends greatly on such plant properties as leaf size, microsite selection, and plant height. A direct and sensitive coupling between atmospheric thermal radiation and plant ecology is apparent, along with corresponding implications associated with atmospheric warming.

Jordan, D.N.; Smith, W.K. (Univ. of Wyoming, Laramie (United States))

1993-06-01

347

Experimental Study on Frost Height of Round Plate Fin-Tube Heat Exchangers for Mobile Heat Pumps  

Directory of Open Access Journals (Sweden)

Full Text Available The objective of this study was to provide experimental data that could be used to predict frost growth and frost performance of a round plate fin-tube heat exchanger for low temperature heat pumps used in zero emission vehicles under cold weather conditions. In this study, round plate fin-tube heat exchangers were tested with variation of the fin space, air flow rate, relative humidity, and inlet air temperature. Frost height was measured and considered with the boundary layer interruption between fins. Frost height for 8.0 mm of fin space was increased by approximately 91.9% with an increase of relative humidity from 50.0% to 80.0%. The growth rate of frost height at 1.2 m3/min was observed to be 13.0% greater than that at 0.8 m3/min. Finally, the variation of the blockage ratio with fin space would be an important reference for designing advanced heat exchangers that operate under cold weather conditions.

Moo-Yeon Lee; Yongchan Kim; Dong-Yeon Lee

2012-01-01

348

Changes of Frost Damage and Treeline Advance for Swiss Stone Pine in the Calimani Mts. (Eastern Carpathians, Romania)  

Directory of Open Access Journals (Sweden)

Full Text Available Checking the tree-ring structure of 39 living and 9 crossdated dead samples of Swissstone pine (Pinus cembra L.) collected from the upper timberline of the CalimaniMts. we haveidentified 59 frost rings over the past 250 years. We found concentrated occurrence of frost events inthree decades: in the 1790s, 1810s and 1910s. No frost ring was observed in two bidecadal periods:1750-1770 and 1850-1870. Out of the analysed interval 1963-2004 is the longest period without frostring occurrence. After 1920 both frequency and severity of frost events seem to decrease compared tothe prior 170 years. We determined the altitude of highest growing stone pine individuals in theBradului Ciont–Pietrosu region in June, 2006. Individuals were sorted into tree-form or bush-likemorphological groups. Mean elevation data of the groups were corrected by an estimated constant biasof GPS measurements (-30 m). Comparing the corrected values to early 20th century inventory data65 m and 95 m upward migration was determined for treeline and boundary of bush-like occurence,respectively. The parallel results suggest that the 20th century advance of the upper forest limit wasdue to the decrease of frost stress at the zone of timberline.

KERN, Zoltán; POPA, Ionel

2008-01-01

349

Rossby wave propagation tracks in southern hemisphere mean basic flows associated to generalized frosts over southern South America  

Directory of Open Access Journals (Sweden)

Full Text Available Based on previous observational studies on cold extreme events over southern South America, some recent studies suggest a possible relationship between Rossby wave propagation remotely triggered and the occurrence of frost. Using the concept of linear theory of Rossby wave propagation, this paper analyzes the propagation of such waves in two different basic states that correspond to austral winters with maximum and minimum generalized frost frequency of occurrence in the Wet Pampa (central-northwest Argentina). In order to de- termine the wave trajectories, the ray tracing technique is used in this study. Some theoretical discussion about this technique is also presented. The analysis of the basic state, from a theoretical point of view and based on the calculation of ray tracings, corroborates that remotely excited Rossby waves is the mechanism that favors the maximum occurrence of generalized frosts. The basic state in which the waves propagate is what conditions the places where they are excited. The Rossby waves are excited in determined places of the atmosphere, propagating towards South America along the jet streams that act as wave guides, favoring the generation of generalized frosts. In summary, this paper presents an overview of the ray tracing technique and how it can be used to investigate an important synoptic event, such as frost in a specific region, and its relationship with the propagation of large scale planetary waves.

G. V. MÜLLER; T. AMBRIZZI

2010-01-01

350

THE EFFECT OF CULTIVAR AND BEARING TREE ON BUD DIFFERENTIATION, FROST DAMAGE AND FRUIT SET IN APPLE  

Directory of Open Access Journals (Sweden)

Full Text Available After severe winter frost, an examination was initiated of frost damage suffered by Idared and Golden Delicious clone B. The cultivars differed significantly in the differentiation intensity, the hare of damaged differentiated buds, but not in share of damaged undifferentiated buds. In both cultivars the bud damage was more intensive on long bearing wood than on spur, regardless differentiation grade. The interaction between the cultivar and the bearing wood was insignificant. The flower bud differentiation was better in Idared, but it also suffered more frost damage than the Golden Delicious clone B with differentiated buds, but not than that with undifferentiated buds. In both cultivars frost damage increases with increase of differentiated flower buds (R2=0.759; P?0.001). The fruit set was within the limits of expectation only on the spurs of the Golden Delicious clone B, which showed strong tendency towards fruit set on long bearing shoots. In 2000, the yield of the cultivars was almost equal, as the result of thinning due to the frost damage on Idared.

Nikola Pavi?i?; Ivo Krpina; Tomislav Jemri?; Dražen Kau?i?; Dražen Blaškovi?; Martina Skendrovi?

2004-01-01

351

Liquefaction of soils  

Energy Technology Data Exchange (ETDEWEB)

Liquefaction during earthquakes has been a significant cause of failure of onshore as well as offshore structures. The phenomenon of liquefaction has been studied extensibly for the case of cohesionless soils. Fine grained soils such as silts and sands with fines have generally been considered as non-liquefiable in the past. Recent studies have shown that fine grained soils in certain situations may be susceptible to liquefaction. This paper will present a brief review of the recent work on the liquefaction of fine grained soils and the results of an investigation conducted by the authors on liquefaction behavior of silty soils.

Puri, V.K. [Southern Illinois Univ., Carbondale, IL (United States); Prakash, S.; Kumar, S. [Univ. of Missouri, Rolla, MO (United States)

1995-12-31

352

Liquid-infused nanostructured surfaces with extreme anti-ice and anti-frost performance.  

UK PubMed Central (United Kingdom)

Ice-repellent coatings can have significant impact on global energy savings and improving safety in many infrastructures, transportation, and cooling systems. Recent efforts for developing ice-phobic surfaces have been mostly devoted to utilizing lotus-leaf-inspired superhydrophobic surfaces, yet these surfaces fail in high-humidity conditions due to water condensation and frost formation and even lead to increased ice adhesion due to a large surface area. We report a radically different type of ice-repellent material based on slippery, liquid-infused porous surfaces (SLIPS), where a stable, ultrasmooth, low-hysteresis lubricant overlayer is maintained by infusing a water-immiscible liquid into a nanostructured surface chemically functionalized to have a high affinity to the infiltrated liquid and lock it in place. We develop a direct fabrication method of SLIPS on industrially relevant metals, particularly aluminum, one of the most widely used lightweight structural materials. We demonstrate that SLIPS-coated Al surfaces not only suppress ice/frost accretion by effectively removing condensed moisture but also exhibit at least an order of magnitude lower ice adhesion than state-of-the-art materials. On the basis of a theoretical analysis followed by extensive icing/deicing experiments, we discuss special advantages of SLIPS as ice-repellent surfaces: highly reduced sliding droplet sizes resulting from the extremely low contact angle hysteresis. We show that our surfaces remain essentially frost-free in which any conventional materials accumulate ice. These results indicate that SLIPS is a promising candidate for developing robust anti-icing materials for broad applications, such as refrigeration, aviation, roofs, wires, outdoor signs, railings, and wind turbines.

Kim P; Wong TS; Alvarenga J; Kreder MJ; Adorno-Martinez WE; Aizenberg J

2012-08-01

353

CLAS+FROST: new generation of photoproduction experiments at Jefferson Lab  

CERN Document Server

A large part of the experimental program in Hall B of the Jefferson Lab is dedicated to baryon spectroscopy. Photoproduction experiments are essential part of this program. CEBAF Large Acceptance Spectrometer (CLAS) and availability of circularly and linearly polarized tagged photon beams provide unique conditions for this type of experiments. Recent addition of the Frozen Spin Target (FROST) gives a remarkable opportunity to measure double and triple polarization observables for different pseudo-scalar meson photoproduction processes. For the first time, a complete or nearly complete experiment becomes possible and will allow model independent extraction of the reaction amplitude. An overview of the experiment and its current status is presented.

Pasyuk, Eugene

2009-01-01

354

CLAS+FROST: new generation of photoproduction experiments at jefferson lab  

International Nuclear Information System (INIS)

A large part of the experimental program in Hall B of the Jefferson Lab is dedicated to baryon spectroscopy. Photoproduction experiments are essential part of this program. CEBAF Large Acceptance Spectrometer (CLAS) and availability of circularly and linearly polarized tagged photon beams provide unique conditions for this type of experiments. Recent addition of the Frozen Spin Target (FROST) gives a remarkable opportunity to measure double and triple polarization observables for different pseudo-scalar meson photoproduction processes. For the first time, a complete or nearly complete experiment becomes possible and will allow model independent extraction of the reaction amplitude. An overview of the experiment and its current status is presented. (author)

2009-01-01

355

Scattering properties of natural snow and frost - Comparison with icy satellite photometry  

International Nuclear Information System (INIS)

The Hapke (1986) equation is presently fit to ascertain the single-scattering albedo of the icy satellites of Uranus and Neptune and the one-term Henyey-Greenstein particle-phase function g for each of the Middleton and Mungall (1952) goniophotometric data samples. There emerge both very high single-scattering albedos and strongly forward-scattering particle phase functions; while these are in keeping with Mie theory-based theoretical considerations, they contrast with the observed backscattering behavior of icy satellites. It is suggested the icy satellite frost grains are aggregated into particles of complex texture, which produce the unusual backscattering behavior. 26 refs

1990-01-01

356

Evaluations on power ramp data of PWR fuels by FROST and THERMOST codes  

International Nuclear Information System (INIS)

Power ramp data of Mitsubishi's PWR fuel rods tested in R-2, Studsvik were analyzed by FROST and THERMOST codes. The predictions of both codes show relatively good agreement with many measurements during or after irradiation. Especially detailed behaviours of the fuel related to axial PCMI, such as rod elongation-relaxation during ramp test, are predicted successfully. Axial and radial deformations of claddings are simulated so well that calculated stresses in claddings are considered to be reliable. The ramp data used in present analyses were obtained in two joint programs with five Japanese PWR utilities (KEPCO, KYEPCO, SEPCO, HEPCO, and JAPCO). (author)

1984-01-01

357

Coagulation of particles in Saturn's rings - Measurements of the cohesive force of water frost  

International Nuclear Information System (INIS)

Experimental data are presented on the sticking force of water ice particles which are indicative of the role that the cohesive properties of such particles could play in the dynamics of Saturn ring particles. Sticking forces are dependent on particle impact velocities; a Velcro model is devised to describe the surface structure involved in sticking. The data indicate that below the critical impact velocity of about 0.03 cm/sec, particle cohesion always occurs. Due to the optical depth of micron-sized grains in the Saturn rings, particles are hypothesized to be coated with a layer of frost which will render cohesion an important ring-dynamics process. 14 refs.

1991-01-01

358

Solar Reflectance Measurements of Calibration Targets and Martian South Polar Frosts  

Science.gov (United States)

The Viking Infrared Thermal Mapper (IRTM) solar reflectance measurements revealed anomalous photometric properties of the martian polar frosts. For example, while most planetary surfaces exhibit marked brightening towards high illumination angles, the IRTM observations of the martian south polar cap (SPC) show the exactly opposite trend. Recently, several hypotheses have been proposed to explain this unusual behavior, such as the effects of dust contamination or the effects of frost texture and opacity. I have analyzed IRTM observations of the SPC in order to reveal basic physical properties of the frost and also to shed light upon the viability of these hypotheses. This thesis includes laboratory measurements along with the IRTM data analysis. The laboratory work consists of the design, fabrication and photometric characterization of calibration targets used by two space-borne instruments, the Pressure Modulator Infrared Radiometer (PMIRR) on the Mars Climate Orbiter mission and the SVET radiometer on the Russian Mars '96 mission. The data analysis portion consists of a thorough study of the Viking IRTM solar channel observations of the south polar cap. The full seasonal history of cap reflectance is shown here, along with analysis of reflectance as a function of photometric angles, local time, season, and other parameters. The hypotheses mentioned above, together with others, have all been reexamined in light of the new findings of this work. This study finds that no single hypothesis put forth to date can account for all the variability and phenomena found in the data. Alone, neither dust deposition nor removal, water contamination, geography, nor atmospheric circulation, does well at predicting the IRTM south polar observations. Each may play a role, and it appears clear now that a combination of several processes controls the cap reflectance. At this time, there is still no unambiguous answer to which processes dominate. Furthermore, the idea of unusual frost formations with strangely behaving reflectance functions has been examined and found to not play a major role in the reflectance of the SPC. Also, the idea of the formation of a semi-transparent ice sheet, its development with season, and the implications it would have on the reflectance of the SPC has also been studied.

Ono, Adrienne Momilani

359

Effects of fin pitch and array of the frost layer growth on extended surface of a heat exchanger  

International Nuclear Information System (INIS)

This paper presents the effects of the fin array and pitch on the frost layer growth of a heat exchanger. The numerical results are compared with experimental data of a cold plate to validate the present model, and agree well with experimental data within a maximum error of 8%. The characteristics of the frost formation on staggered fin array are somewhat different from those of in-line array. For fin pitch below 10 mm, the frost layer growth of second fin in the staggered array is affected by that of first fin. The heat transfer of single fin deteriorate with decreasing fin pitch regardless of fin array, however, the thermal performance of a heat exchanger, considering increase of heat surface area, becomes better

2003-01-01

360

Evaluación de daños por heladas tardías en ensayos de procedencias de pino oregón introducidos en el norte de la Región Andino Patagónica Argentina/ Evaluation of damage by late frosts in provenances trials of Douglas-fir introduced in Argentinian North Patagonia  

Scientific Electronic Library Online (English)

Full Text Available Abstract in spanish La susceptibilidad a las heladas tardías de la fuente de semilla actualmente utilizada es una de las principales características adaptativas que limitan la ampliación del área de plantación de pino oregón (Pseudotsuga menziesii (Mirb.) Franco) en la Región Norpatagónica de la Argentina. En dos ensayos de procedencias de esta especie se registró el daño provocado por heladas de primavera de hasta -7º C de mínima absoluta. En ambos ensayos se encontraron diferen (more) cias significativas entre los tratamientos. En el ensayo en el que se registraron mínimas más rigurosas pudieron establecerse correlaciones altamente significativas entre el porcentaje de daño por heladas con la longitud (r = 0,86) y altitud (r = - 0,75) del origen de la semilla, y una menor asociación con la altura media de las plantas en vivero (r = 0,55) y la latitud de origen (r = 0,44). Considerando que los orígenes costeros son los de mayor potencial de crecimiento, estos resultados indican que la selección en base a ese único criterio podría producir una selección indirecta de genotipos susceptibles. Finalmente se recomienda la evaluación simultánea de rendimiento y susceptibilidad para extender el cultivo de la especie hacia áreas de mayor riesgo de heladas. Abstract in english The susceptibility to late frost of the seed source used for afforestations at the moment it is one of the main adaptatives characteristic limiting the increase of the planted area of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) in Argentinien North Patagonia Region. In two provenances trials of this species we registered frost injury caused by absolute minimum temperature of -7º C during spring. In both sites we found significant differences among treatments. We f (more) ound a strong correlation between the percentage of frost injury and seed source longitude (r = 0.86) and with seed source altitude (r = 0.75) in the trail that registered the most rigorous minimum. In this trial we found also a weaker association with nursery mean heights (r = 0.55) and the origin latitude (r = 0.44). Considering that coastal origins are those of better potential growth, selection based only growth criteria could produce an indirect selection of susceptible genotypes. Finally we recommend the simultaneous evaluation of yield and susceptibility to be able to extend the specie cultivation towards other areas with increased frost risks.

MARTINEZ MEIER, ALEJANDRO; MONDINO, VICTOR; GALLO, LEONARDO

2005-12-01

 
 
 
 
361

Evaluación de daños por heladas tardías en ensayos de procedencias de pino oregón introducidos en el norte de la Región Andino Patagónica Argentina Evaluation of damage by late frosts in provenances trials of Douglas-fir introduced in Argentinian North Patagonia  

Directory of Open Access Journals (Sweden)

Full Text Available La susceptibilidad a las heladas tardías de la fuente de semilla actualmente utilizada es una de las principales características adaptativas que limitan la ampliación del área de plantación de pino oregón (Pseudotsuga menziesii (Mirb.) Franco) en la Región Norpatagónica de la Argentina. En dos ensayos de procedencias de esta especie se registró el daño provocado por heladas de primavera de hasta -7º C de mínima absoluta. En ambos ensayos se encontraron diferencias significativas entre los tratamientos. En el ensayo en el que se registraron mínimas más rigurosas pudieron establecerse correlaciones altamente significativas entre el porcentaje de daño por heladas con la longitud (r = 0,86) y altitud (r = - 0,75) del origen de la semilla, y una menor asociación con la altura media de las plantas en vivero (r = 0,55) y la latitud de origen (r = 0,44). Considerando que los orígenes costeros son los de mayor potencial de crecimiento, estos resultados indican que la selección en base a ese único criterio podría producir una selección indirecta de genotipos susceptibles. Finalmente se recomienda la evaluación simultánea de rendimiento y susceptibilidad para extender el cultivo de la especie hacia áreas de mayor riesgo de heladas.The susceptibility to late frost of the seed source used for afforestations at the moment it is one of the main adaptatives characteristic limiting the increase of the planted area of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) in Argentinien North Patagonia Region. In two provenances trials of this species we registered frost injury caused by absolute minimum temperature of -7º C during spring. In both sites we found significant differences among treatments. We found a strong correlation between the percentage of frost injury and seed source longitude (r = 0.86) and with seed source altitude (r = 0.75) in the trail that registered the most rigorous minimum. In this trial we found also a weaker association with nursery mean heights (r = 0.55) and the origin latitude (r = 0.44). Considering that coastal origins are those of better potential growth, selection based only growth criteria could produce an indirect selection of susceptible genotypes. Finally we recommend the simultaneous evaluation of yield and susceptibility to be able to extend the specie cultivation towards other areas with increased frost risks.

ALEJANDRO MARTINEZ MEIER; VICTOR MONDINO; LEONARDO GALLO

2005-01-01

362

Effects of frost on wildflowers: an unexpected consequence of climate change--image 20 of 22  

Science.gov (United States)

A Mormon fritillary butterfly (Speyeria mormonia) visiting flowers of the fleabane daisy (Erigeron speciosus), an important and preferred nectar resource. Flower buds of E. speciosus are frost-sensitive. Egg production of female S. mormonia butterflies is limited by the amount of nectar they can collect (which is unusual for butterflies). Therefore, spring frosts that kill E. speciosus flowers impair reproduction in the fritillary butterfly. The work on butterfly populations was done by Dr. Carol Boggs from Stanford University. She had not published the results of her 9-year study because she couldn't figure out why the butterfly populations were so variable. She happened to mention the study, and the fact that the butterflies relied heavily on E. speciosus flowers, to David Inouye, who replied that he had long-term data on the flowers. The resulting collaboration resulted in a publication that links the impact of climate change on the plants to the population biology of the butterflies. One benefit of working at a field station is that unexpected collaborations can arise, as did this one involving the butterfly and flower datasets.

Inouye, David

2012-02-28

363

The FROST code for predicting in-reactor behaviours of LWR fuel rod  

International Nuclear Information System (INIS)

FROST (Fuel Rod Stress Analysis) is a computor code which analyzes irradiation behaviours - especially the stresses and strains - of a fuel rod for LWR. The handling of dynamics of the code is essentially based on well-known CYGRO code which deals with one axial segment of a rod. However, the capability of FROST has further been extended so that it could handle the axial variation effect such as axial power shape, fission gas pressure and axial PCI by applying the above one-segmental mechanics to all the axial segments of a rod. In addition, most of the models describing the phenomena were replaced by relatively recent LWR based correlations. In this code, a fuel rod is divided into desired number of axial segments and radial rings for both pellet and clad. Every phenomenon occurring in an elementary ring is reduced to the dimensional change of the ring, and the overall deformation of one axial segment is calculated by using the finite element method. Then all the segments are axially connected together with a plenum to calculate fission gas pressure and axial PCI. The latter is done by newly developed axial interaction model which can deal with the plenum spring and pellet-pellet axial gaps, in addition to the usual mechanisms of sticking and slipping. These procedures are repeated following the irradiation history, and in the course of them, the deformations, stresses, strains and the other phenomena are calculated. (orig.)

1979-08-21

364

Frost-acclimation of photosynthesis in overwintering Mediterranean holm oak, grown in Central Europe  

Directory of Open Access Journals (Sweden)

Full Text Available As a consequence of global change, forestry in Central Europe has to expect and be prepared for an increase of hot and dry summers in the near future. In two model plantations of the Mediterranean holm oak (Quercus ilex L.) in Central Europe (Rhine-Main basin) we tested its potential as a future forestry tree for drought-threatened stands by studying its overwintering strategy under harsh winter conditions. During prolonged frost periods, chronic photoinhibition was developed, which lasted until the end of the frost period. Nearly all plants survived minimum temperatures of - 16 to -18°C and their photosynthetic apparatus recovered completely during late winter. A detailed study of the temperature dependence of chlorophyll (chl) fluorescence parameters of the OJIP test revealed statistically significant correlations between minimum temperature and maximum quantum yield of primary photochemistry (Fv/Fm), absorption rate/reaction centre (ABS/RC), dissipation rate/reaction centre (DI0/RC) and electron transport rate/reaction centre (ET0/RC) as well as with the deepoxidation state (DES) of the xanthophyll pigments. The DES correlated with Fv/Fm, ABS/RC, DI0/RC and ET0/RC. It is concluded, that from the point of view of the winter hardiness of the photosynthetic apparatus, Q. ilex should be further investigated as a potential future forestry tree also for very dry and warm stands in Central Europe under the scenarios of climate change.

Ellen Pflug; Wolfgang Brüggemann

2012-01-01

365

ASSESSMENT OF CERAMIC TILE FROST RESISTANCE BY MEANS OF THE FREQUENCY INSPECTION METHOD  

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Full Text Available The paper presents some results of our experimental analysis of ceramic cladding element frost resistance, particular attention being paid to the application of the frequency inspection method. Three different sets of ceramic tiles of the Ia class to EN 14 411 B standard made by various manufacturers have been analyzed. The ceramic tiles under investigation have been subjected to freeze-thaw-cycle-based degradation in compliance with the relevant ?SN EN ISO 10545-12 standard. Furthermore, accelerated degradation procedure has been applied to selected test specimens, consisting in reducing the temperature of water soaked ceramic tiles in the course of the degradation cycles down –70°C. To verify the correctness of the frequency inspection results, additional physical properties of the ceramic tiles under test have been measured, such as, the ceramic tile strength limit, modulus of elasticity and modulus of deformability, resulting from the flexural tensile strength tests, integrity defect and surface micro-geometry tracking. It has been proved that the acoustic method of frequency inspection is a sensitive indicator of the structure condition and can be applied to the ceramic cladding element frost resistance and service life prediction assessment.

IVETA PLŠKOVÁ; ZDEN?K CHOBOLA; MICHAL MATYSÍK

2011-01-01

366

Using Synchrotron Radiation-Based Infrared Microspectroscopy to Reveal Microchemical Structure Characterization: Frost Damaged Wheat vs. Normal Wheat  

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This study was conducted to compare: (1) protein chemical characteristics, including the amide I and II region, as well as protein secondary structure; and (2) carbohydrate internal structure and functional groups spectral intensities between the frost damaged wheat and normal wheat using synchrotro...

Hangshu Xin; Xuewei Zhang; Peiqiang Yu

367

Proteins Involved in Distinct Phases of Cold Hardening Process in Frost Resistant Winter Barley (Hordeum vulgare L.) cv Luxor  

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Winter barley is an economically important cereal crop grown in higher latitudes and altitudes where low temperatures represent an important environmental constraint limiting crop productivity. In this study changes in proteome of leaves and crowns in a frost tolerant winter barley cv. Luxor in rela...

Iva Hlavá?ková; Pavel Vítámvás; Ji?í Šantr??ek; Klára Kosová; Sylva Zelenková; Ilja Tom Prášil; Jaroslava Ovesná

368

Calculation and Analysis of Frost Duration Times by Using Delphi Programming: A Case Study in Lorestan, Iran  

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The purpose of the present study is to calculate the duration times of frosts by Delphi programming. To do this, the data related to the daily minimum temperature of four meteorology stations of Lorestan Province, i.e., Khoram-Abad, Boroujerd, Doroud and Aligoudarz that enjoy a ten-year statistics (...

Z. Hejazizadeh; M.H. Naserzadeh

369

Effects of Condensate and Initial Formation of Thin Frost Layer on Evaporator Coil Performance of Room Air-Conditioners  

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Full Text Available This study investigated experimentally and theoretically, how condensate and initial formation of a thin frost layer on thesurface of the evaporator affects the evaporator performance of room air-conditioners compared to dry coil conditions. The theoretically obtained results were validated with the measured values in both wet and initial frost formation conditions and a good correlation was found. The results indicated that, at the same range of change in face velocity value, the total conductivity of a dry coil (UA) dry is increased by 38.8%. However, when it is combined with an increase in latent heat to the evaporator total cooling capacity ratio value (Qlat/Q) of 10.6%, the total conductivity of wet coil (UA) wet is 45.4%. These results clearly indicate that the evaporator coil is characterized by higher performance under wet conditions compared to dry coil conditions. The results also show that the total conductivity after initial formation of a thin frost layer (UA) Fr has a higher value by about 8.2% than the dry coil condition. Moreover, the degradation in the evaporator coil performance underthin frost with a thickness up to one mm is only about 6.7%.

Ahmed Hamza H. Ali; Ibrahim M. Ismail

2007-01-01

370

Evaluation of the occurence of agricultural frost in state of Parana, Brazil, generated by a regional forecast model  

Science.gov (United States)

This study evaluated the potential use of a regional atmospheric model to predict the occurrence of agricultural frost three days in advance, as based on the vulnerability to low temperatures of the main crops in eight locations in the state of Parana, Brazil, between 2000 and 2007. Based on the reported occurrence of frosts, the values of the air temperature observed at meteorological stations were compared with the 66 h advance predictions obtained by the model. In general, we observed a slight overestimation of the air temperature values for all of the locations during the frost events. However, regression analyses demonstrated a good quality of the prediction of the model despite the data grid being relatively coarse. The coefficients of determination (R2) were larger than 0.65, whereas the systematic errors varied between 0.26 and 0.69°C, and the magnitude of error does not exceed 1.7°C. The hit rates of the categorical forecasts showed that the temperature 66 hours in advance was adequate to detect the occurrence of frost because the accuracy of forecasting exceeded 0.80, the probability of detection reached 0.70, and the false alarm rate did not exceeded 0.3.

Giarolla, Angelica; Chou, Sin C.; Faria, Rogerio T.

2013-04-01

371

Using Synchrotron Radiation-Based Infrared Microspectroscopy to Reveal Microchemical Structure Characterization: Frost Damaged Wheat vs. Normal Wheat  

Science.gov (United States)

This study was conducted to compare: (1) protein chemical characteristics, including the amide I and II region, as well as protein secondary structure; and (2) carbohydrate internal structure and functional groups spectral intensities between the frost damaged wheat and normal wheat using synchrotron radiation-based Fourier transform infrared microspectroscopy (SR-FTIRM). Fingerprint regions of specific interest in our study involved protein and carbohydrate functional group band assignments, including protein amide I and II (ca. 1774–1475 cm?1), structural carbohydrates (SCHO, ca. 1498–1176 cm?1), cellulosic compounds (CELC, ca. 1295–1176 cm?1), total carbohydrates (CHO, ca. 1191–906 cm?1) and non-structural carbohydrates (NSCHO, ca. 954–809 cm?1). The results showed that frost did cause variations in spectral profiles in wheat grains. Compared with healthy wheat grains, frost damaged wheat had significantly lower (p frost damage, and these structural variations might be a major reason for the decreases in nutritive values, nutrients availability and milling and baking quality in wheat grains.

Xin, Hangshu; Zhang, Xuewei; Yu, Peiqiang

2013-01-01

372

Digital Image Sensor-Based Assessment of the Status of Oat (Avena sativa L.) Crops after Frost Damage  

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The aim of this paper is to classify the land covered with oat crops, and the quantification of frost damage on oats, while plants are still in the flowering stage. The images are taken by a digital colour camera CCD-based sensor. Unsupervised classification methods are applied because the plants pr...

Antonia Macedo-Cruz; Gonzalo Pajares; Matilde Santos; Isidro Villegas-Romero

373

Molecular ennoblement of frost tolerance and phenology in Salix. Final report; Molekylaer foeraedling av frostresistens och fenologi i Salix. Slutrapport  

Energy Technology Data Exchange (ETDEWEB)

Two Salix genetic linkage maps have been produced. One is based on a cross between a S.viminalis clone (78183) and a S. viminalis x S. schwerinii hybrid (Bjoern), the second on a cross between Jorunn (S. viminalis) and a russian clone (SW1290). Both crosses have been utilised in field and greenhouse experiments to map genes affecting important traits. QTLs for growth related traits were mapped using the 78182xBjoern cross in one field trial measured during four years. QTLs with relatively large effects were detected for several traits, but the stability of the QTLs over years was limited. Extensive artificial frost resistance experiments with the second cross identified several genes (QTLs) affecting frost tolerance. Frost tolerance genes were identified before the start of the acclimation process, but they were replaced by other genes later during the acclimation process. The results support that frost tolerance is a complex process controlled by a large number of genes. An initial resistance is controlled by genes different from those that are important during the acclimation process.

Lagercrantz, U. [Swedish Univ. of Agricultural Sciences, Uppsala (Sweden). Dept. of Plant Biology

2001-09-01

374

Peripheral capillary nonperfusion and full-field electroretinographic changes in eyes with frosted branch-like appearance retinal vasculitis  

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Full Text Available Yoshitsugu Matsui, Hideyuki Tsukitome, Eriko Uchiyama, Yuko Wada, Tatsuya Yagi, Hisashi Matsubara, Mineo KondoDepartment of Ophthalmology, Mie University Graduate School of Medicine, Tsu, JapanAbstract: We report a patient with frosted branch-like appearance retinal vasculitis associated with peripheral capillary nonperfusion and full-field electroretinographic changes. A 62-year-old man presented with sudden bilateral decreased vision accompanied by headaches. His best-corrected visual acuity was 0.01 in both eyes. Fundus examination and fluorescein angiography showed bilateral frosted branch-like appearance retinal vasculitis, and spectral-domain optical coherence tomography showed severe macular edema in both eyes. The cerebrospinal fluid analyses showed an increased lymphocyte count and protein levels. He was treated with systemic corticosteroid therapy, and his best-corrected visual acuity improved to 0.8 OD and 1.0 OS at 6 months after onset. However, fluorescein angiography showed a lack of capillary perfusion in the periphery, and the oscillatory potentials on full-field electroretinography were severely reduced in both eyes. These findings indicated extensive retinal ischemia and inner retinal dysfunction, and that fluorescein angiography and full-field electroretinograms can be useful during follow-up of eyes with frosted branch-like appearance retinal vasculitis.Keywords: frosted branch angiitis, aseptic meningitis, optical coherence tomography, electroretinogram, oscillatory potentials

Matsui Y; Tsukitome H; Uchiyama E; Wada Y; Yagi T; Matsubara H; Kondo M

2013-01-01

375

Determination by cryogenic probe of soil ability to restore or store the heat: testing device, experiment and modeling  

Energy Technology Data Exchange (ETDEWEB)

The heat recovery or storage in the ground may be largely enhanced by using the soil as a cold or hot source for a heat pump below 0 degree C. This extension to negative temperatures is set through the utilization of the water phase change latent heat. An experimental study had been cnducted with various soils, saturated or not, and the ability to undergo successive frost-defrost cycles is examined.

El Kadiri, M.

1986-01-01

376