scholarly journals Thermal polarization mechanism of sap flow during the spring equinox

10.12737/8436 ◽  
2015 ◽  
Vol 4 (4) ◽  
pp. 26-35 ◽  
Author(s):  
Камалова ◽  
Nina Kamalova ◽  
Евсикова ◽  
Natalya Evsikova ◽  
Матвеев ◽  
...  
Keyword(s):  
Temperature Change ◽  
Sap Flow ◽  
Maximum Temperature ◽  
Winter Period ◽  
Polarization Effects ◽  
Spring Equinox ◽  
Winter Temperatures ◽  
Polarization Mechanism ◽  
In Series ◽  
Thermal Polarization

This article seeks the answer to the question of how the distribution of the concentration of dissolved minerals in the sap after the winter period in the xylem is made, if in the fall due to low winter temperatures tree tends to reduce the amount of water and sap in its pores. In search of an answer it is invited to consider thermal polarization effects in the xylem of tree trunks during the spring equinox. The results of monitoring of daily average temperature showed that during the winter the temperature of the day varies in the amount of one and a half times greater than during the night, and in February this change is almost the same. Whereas in March the temperature change occurs in series, they sometimes are different in three times. Maximum temperature change for the day and night is achieved during the spring equinox, on average, it is ten degrees. Such a temperature change is accompanied by sharp changes in temperature during the days, which, according to the estimates, give rise to an electric field in the xylem along the trunk. Under this approach, in the work estimated expression was theoretically derived for the concentration of salt ions in the xylem of tree trunks, giving reason to believe that the described mechanism also contributes to the value of the osmotic pressure. All these considerations lead to the assumption that intensive spring sap flow (in the absence of currents of transpiration) is stimulated by thermal polarization effects in the xylem of the trunk, caused by the intense ambient temperature changes during this period.

Design and Fabrication of a Magnetocaloric Microcooler

2005 ◽  
Author(s):  
Sangchae Kim ◽  
Bharath Bethala ◽  
Simone Ghirlanda ◽  
Senthil N. Sambandam ◽  
Shekhar Bhansali
Keyword(s):  
Magnetic Field ◽  
Ambient Temperature ◽  
Temperature Change ◽  
Entropy Change ◽  
Temperature Sensors ◽  
Experimental Results ◽  
Maximum Temperature ◽  
Alternative Technology ◽  
Temperature Conditions ◽  
Si Wafer

Magnetocaloric refrigeration is increasingly being explored as an alternative technology for cooling. This paper presents the design and fabrication of a micromachined magnetocaloric cooler. The cooler consists of fluidic microchannels (in a Si wafer), diffused temperature sensors, and a Gd5(Si2Ge2) magnetocaloric refrigeration element. A magnetic field of 1.5 T is applied using an electromagnet to change the entropy of the magnetocaloric element for different ambient temperature conditions ranging from 258 K to 280 K, and the results are discussed. The tests show a maximum temperature change of 7 K on the magnetocaloric element at 258 K. The experimental results co-relate well with the entropy change of the material.

scholarly journals Temperature Change and Its Elevation Dependency in the Source Region of the Yangtze River and Yellow River

2014 ◽  
Vol 6 (2) ◽  
pp. 124 ◽  
Author(s):  
Chongyi E ◽  
Hongchang Hu ◽  
Hong Xie ◽  
Yongjuan Sun
Keyword(s):  
Temperature Change ◽  
Minimum Temperature ◽  
Yangtze River ◽  
Yellow River ◽  
Source Region ◽  
Maximum Temperature ◽  
Climatic Data ◽  
The Yangtze River ◽  
Extreme Minimum Temperature ◽  
The Mean

The study of temperature change and its elevation dependency in the source region of the Yangtze River and Yellow River have been insufficient owing to the lack of adequate observation stations and long-term climatic data. In this study five temperature indices of 32 stations from 1961 to 2007 in and near the source region are used. The 32 stations all have experienced significant warming; the warming amplitudes are higher than the mean warming amplitude of the Qinghai-Tibetan plateau. The warming amplitudes and the numbers of stations showing significant warming trends in mean minimum temperature and extreme minimum temperature are higher than that of the mean maximum temperature and extreme maximum temperature. The elevation dependency of climatic warming and the amount of significant warming stations are not obvious; the influence of human activity and urbanization may be higher. The warming amplitudes of 26 stations above 3000 m tend to be uniform, and there is no significant law at 6 stations below 3000 m. On the contrary, the ratio of stations showing significant warming in minimum temperature above 4000 m is far less than that of the stations below 4000 m.

scholarly journals Leaf proline content and its relation to fruit load and flowering in citrus under field conditions

2019 ◽  
Vol 41 (2) ◽  
Author(s):  
Mercedes Arias-Sibillotte ◽  
Alejandra Borges ◽  
Pedro Díaz ◽  
Alejandra Ferenczi ◽  
Vivian Severino
Keyword(s):  
Floral Induction ◽  
Proline Content ◽  
Total Amino Acid ◽  
Winter Period ◽  
Citrus Species ◽  
Rest Periods ◽  
Winter Temperatures ◽  
Tolerance Response ◽  
Citrus Leaves ◽  
Main Factor

Abstract Citrus species grown in temperate zones have sprouting inhibited in winter and this is retaken in spring when they also bloom. The main factor that defines the vegetative or reproductive destiny of the buds is the presence of fruits in development. Low winter temperatures slow plant metabolism, which has been reported as necessary for the expression of the reproductive program. During the winter period of the annual cycle, osmotically active compounds such as proline are increased as part of the cold tolerance response. We investigated whether the presence of developing fruit and the application of exogenous gibberellins affect the proline level in citrus leaves. In an orchard of adult ‘Montenegrina’ mandarin trees, leaf proline contents were measured over two rest periods for branches with or without fruits. Branches that bloomed, the ones that did not have developing fruits, had higher proline levels as well as higher proline: chlorophyll and proline: total amino acid ratios than did branches with fruits. However, the application of exogenous gibberellins, which reduced flowering, did not affect proline content during the same periods. We discuss the ways in which proline may be involved in floral induction in citrus.

Study on the Cooling System of Super-Capacitors for Hybrid Electric Vehicle

2014 ◽  
Vol 492 ◽  
pp. 37-42 ◽  
Author(s):  
Zheng Peng Xia ◽  
Chen Quan Zhou ◽  
Dan Shen ◽  
Hong Jun Ni ◽  
Yin Nan Yuan ◽  
...  
Keyword(s):  
Electric Vehicle ◽  
Hybrid Electric Vehicle ◽  
Cooling System ◽  
Maximum Temperature ◽  
Air Cooling ◽  
Maximum Temperature Difference ◽  
Heating Mechanism ◽  
In Series ◽  
Hybrid Electric ◽  
Super Capacitors

The heating mechanism of the capacitor is researched, the air cooling structure is designed of the capacitors, the model of the cooling of the capacitors is established for the heating phenomenon occurs during the charging and discharging process for super capacitors in series of hybrid electric vehicle. The model of the cooling is simulated based on the software of Star CCM +. The results of experiment show that the maximum temperature difference is less than 5°C among the capacitors, which ensures the consistency of the capacitors working temperature and proves the capacitors work substantially well.

Effect of Heat-Reflective Insulation Coating on Exterior Walls of Building Energy Consumption in Summer

2011 ◽  
Vol 105-107 ◽  
pp. 922-925 ◽  
Author(s):  
Chao He ◽  
Wei Lin Guo ◽  
Yi Yun Huang
Keyword(s):  
Energy Saving ◽  
Temperature Change ◽  
Air Temperature ◽  
Heat Insulation ◽  
Maximum Temperature ◽  
Heat Gain ◽  
Insulation Coating ◽  
Building Wall ◽  
The Mean ◽  
Saving Effect

To discuss the effect of energy saving of heat-reflective insulation coating on exterior walls of building, the wall temperature change of two test rooms with heat insulation or not in Hangzhou has been monitored in summer, and the heat flux data of east, south and west walls were analyzed. The results indicate that the temperature of outside wall surface with the heat reflective insulation coating is reduced effectively, and the maximum temperature change was about 9, 10°C. There is a positive proportional between the mean daily air temperature and heat gain that the heat gain increases with the mean daily air temperature. By calculating, the higher the air temperature, the more the cooling effect of coating in summer. But the higher the mean daily temperature do not mean that the more heat gain in summer. The result shows the energy saving effect of the heat insulation coating on building wall was very obvious in summer in Hangzhou.

Heat generation associated with pressure-induced infiltration in a nanoporous silica gel

2008 ◽  
Vol 23 (7) ◽  
pp. 1902-1906 ◽  
Author(s):  
Aijie Han ◽  
Venkata K. Punyamurtula ◽  
Yu Qiao
Keyword(s):  
Energy Dissipation ◽  
Temperature Variation ◽  
Temperature Change ◽  
Silica Gel ◽  
Heat Generation ◽  
Temperature Increase ◽  
Maximum Temperature ◽  
Nanoporous Silica ◽  
Sorption Behavior ◽  
Multiple Loading

As a liquid moves in the nanopores of a silica gel, because of the hysteresis of sorption behavior, significant energy dissipation can take place. Through a calometric measurement, the characteristics of associated heat generation are investigated. The temperature variation increases with the mass of silica gel, which consists of a reversible part and an irreversible part. The residual temperature change is about 30% to 60% of the maximum temperature increase and can be accumulated as multiple loading cycles are applied.

scholarly journals A 6-yr Climatology of Fronts Affecting Helsinki, Finland, and Their Boundary Layer Structure

2013 ◽  
Vol 52 (9) ◽  
pp. 2106-2124 ◽  
Author(s):  
Victoria A. Sinclair
Keyword(s):  
Boundary Layer ◽  
Temperature Change ◽  
Frontal Zone ◽  
Layer Structure ◽  
Time Of Day ◽  
Lapse Rate ◽  
Maximum Temperature ◽  
Synoptic Scale ◽  
Boundary Layer Structure ◽  
Cold Fronts

AbstractA 6-yr climatology of the frequency, characteristics, and boundary layer structure of synoptic-scale fronts in Helsinki, Finland, was created using significant weather charts and observations from a 327-m-tall mast and from the Station for Measuring Ecosystem–Atmosphere Relationships III. In total, 855 fronts (332 cold fronts, 236 warm fronts, and 287 occluded fronts) affected Helsinki during the 6-yr period, equating to one front every 2.6 days. Seasonal and diurnal cycles were observed, with frontal frequency peaking during the cold season and during daytime. Composites of warm and cold fronts were developed to provide observationally based conceptual models of the low-level structure of fronts at the end of the North Atlantic Ocean storm track. The composite warm front displays a temperature increase of 4.0°C; a broad, forward-tilting frontal zone; and prolonged, weak-to-moderate precipitation. The composite cold front is characterized by a temperature decrease of 4.4°C, a narrow and slightly rearward-tilting frontal zone, and moderate precipitation collocated with the surface front. Relationships between frontal characteristics and the direction from which fronts approached, the season, time of day, prefrontal boundary layer lapse rate, and the location of the wind shift relative to the thermal gradient were investigated. The prefrontal lapse rate was the single most important variable in determining the temperature change, the height of the maximum temperature change, and the near-surface tilt of both warm and cold fronts. This result demonstrates the interaction between boundary layer and synoptic-scale processes that must be captured by numerical weather prediction models to accurately forecast surface fronts.

scholarly journals Heating Performance of MWCNT Module according to Size Effect

2021 ◽  
Vol 21 (5) ◽  
pp. 175-182
Author(s):  
Sohyeon Park ◽  
Sungju An ◽  
Heeyoung Lee ◽  
Donghwi Kim ◽  
Wonseok Chung
Keyword(s):  
Carbon Nanotubes ◽  
Size Effect ◽  
Temperature Change ◽  
Supply Voltage ◽  
Maximum Temperature ◽  
Vehicular Traffic ◽  
Heating Efficiency ◽  
Heating Performance ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes

Black ice is a road-freezing phenomenon that occurs on the surfaces of roads and is caused by sub-zero temperatures. Black ice is dangerous to vehicular traffic because it is difficult for a driver to detect its presence on roads. Further, it causes vehicles to lose traction on roads, thus causing accidents. Therefore, this study aims to solve this problem by utilizing a heating module with multi-walled carbon nanotubes (MWCNTs) and analyzing the heating efficiency according to the size effect of the heating module. The heating modules were divided into cubes (50 × 50 × 50 mm3) and cuboids (100 × 300 × 60 mm3). The parameters considered were the size of the heating module, number of curing days, and supply voltage. The maximum temperature change of the cubes was 75.7 ℃, and the maximum temperature change of the cuboids was 78% of the cube. The thermal images demonstrated that the cuboids exhibited better thermal dispersibility than that exhibited by the cubes. Therefore, the heating efficiency of the cuboids was inferred to be excellent. Thus, the cuboid heating module can be used to reduce the risk of accidents occurring caused by black ice.

scholarly journals Frost risk indicator analysis in Sopron wine region (1961–2016)

Időjárás ◽  
2020 ◽  
Vol 124 (4) ◽  
pp. 447-462
Author(s):  
Tamás Füzi ◽  
Márta Ladányi
Keyword(s):  
Maximum Temperature ◽  
Winter Period ◽  
Time Interval ◽  
Risk Indicator ◽  
Spring Frost ◽  
Regeneration Period ◽  
Recent Climate ◽  
Frost Period ◽  
Frost Free Period ◽  
Wine Region

A characteristic symptom of climate change is the modified distribution of frost events that has fundamental effect on agricultural production. To learn these changes in Sopron region, Hungary, we investigated daily minimum and maximum temperature data of the period 1961–2016 provided by the Hungarian Meteorological Service. The time interval 1961–2016 was split into two (1961–1990 and 1991–2016) in order to compare nearly two climate cycles statistically. We analyzed the 56-year trends of the last frosty day of spring and the first frosty day of autumn as well as the length of the longest yearly frost-free period. As for the winter period (October 16 – February 28), the frequencies of four different strengths of frosty days were examined. We analyzed how often an uninterrupted frost-free period (Tmin>0 °C) longer than 12 days developed between two frosty periods in spring and in autumn, exactly when it occurred (Julian day), and how many days it lasted for. Finally, we investigated the trends of the yearly numbers of spring frosty days and their variances. Amongst others, we show that the length of the longest uninterrupted frost-free periods has increased significantly over the past 56 years, with 70% of years in the recent climate cycle (1991–2016) having frost-free periods of more than 200 days. As an average change per 10 years, the last spring frost period ended four days earlier, while the onset of autumn frost shifted 2 days towards the end of the year. The number of days with minimum temperatures below -15 °C, -10 °C, -5 °C, and below 0 °C decreased significantly during the dormant period. These changes mean a prolongation of the growing season, partly a reduction of the winter regeneration period, and the potential higher overwintering success of the pests. The number of spring frost days also decreased significantly, while their variability has grown markedly.

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