Academic literature on the topic 'Minimum temperature difference'
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Journal articles on the topic "Minimum temperature difference"
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Karim, Mohammad A. "Minimum resolvable temperature difference model: a critical evaluation." Optical Engineering 30, no. 11 (1991): 1788. http://dx.doi.org/10.1117/12.55997.
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Kolobrodov, Valentin G., and Mykola M. Lutsjuk. "Minimum Temperature Difference Perceived for Undersampled Medical Thermal Imager." Research Bulletin of the National Technical University of Ukraine "Kyiv Politechnic Institute", no. 5 (October 31, 2017): 99–103. http://dx.doi.org/10.20535/1810-0546.2017.5.100137.
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Heggs, P. J. "Minimum temperature difference approach concept in heat exchanger networks." Heat Recovery Systems and CHP 9, no. 4 (1989): 367–75. http://dx.doi.org/10.1016/0890-4332(89)90089-6.
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Chrzanowski, Krzysztof. "A minimum-resolvable-temperature difference model for simplified analysis." Infrared Physics 31, no. 4 (1991): 313–18. http://dx.doi.org/10.1016/0020-0891(91)90001-v.
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Groot, Arthur, and Derek W. Carlson. "Influence of shelter on night temperatures, frost damage, and bud break of white spruce seedlings." Canadian Journal of Forest Research 26, no. 9 (1996): 1531–38. http://dx.doi.org/10.1139/x26-172.
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Measurements of frost damage and bud-break phenology were made during the spring of 1993 and 1994 on planted white spruce (Piceaglauca (Moench) Voss) seedlings and on trembling aspen (Populustremuloides Michx.) suckers in combination with measurements of minimum air temperature and long-wave radiation in forest openings of different sizes and configurations (1.5-ha clearcut, 9 and 18 m wide strips, 9 and 18 m diameter circular openings and intact forest) near Chapleau, Ontario. The average minimum air temperature during early summer (May–June) decreased linearly as the sky view factor of the forest openings increased. The average difference in minimum air temperature between the forest and clearcut opening was nearly 3 °C for the period, and during clear night sky conditions, this temperature difference approached 6 °C. The difference in minimum temperature between the forest and clearcut during cloudy night sky conditions was slightly greater than 1 °C. Differences in minimum air temperature between the forest and each of the openings increased with decreasing incoming long-wave radiation. The largest differences occurred between the forest and the clearcut with low incoming long-wave radiation (cloudless nights). Minimum air temperatures in the 9-m strip and 9-m circle differed little from minimums in the forest under all long-wave radiation regimes. Moderation of air temperature on clear nights would be best achieved with sky view factors of less than 0.3, implying a maximum strip width of 0.6 tree heights and a maximum patch diameter of 2.2 tree heights. Damage to white spruce seedlings after a frost in the spring of 1993 increased with increasing sky view factor. Nearly 75% of the seedlings in the clear-cut had medium or heavy frost damage, while only 2% of the seedlings in the 9-m circle and forest were frost damaged. Opening size and configuration had little influence on the timing of bud break in either the white spruce seedlings or the trembling aspen suckers.
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Vieira Junior, Nilson Aparecido, Paulo Henrique Caramori, Marcelo Augusto de Aguiar e. Silva, and Pablo Ricardo Nitsche. "Diferenças de temperatura mínima entre o abrigo meteorológico e a relva em noites com geadas." Semina: Ciências Agrárias 39, no. 6 (2018): 2337. http://dx.doi.org/10.5433/1679-0359.2018v39n6p2337.
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A phenomenon called thermal inversion, in which there is the accumulation of colder and denser air in the layers closer to the soil, occurs in radiative frost nights, resulting in a temperature gradient with differences between the meteorological screen and grass, which vary depending on cooling conditions. Knowing this temperature difference assists in taking preventive measures against radiative frosts, as well as in estimating the probability of their occurrences. In this context, this study aimed to verify the adjustment of different probability distributions to determine the differences between the minimum temperature measured in the meteorological screen and grass temperature below 0 °C for eight regions of the Paraná State, as well as the probability of occurring these differences and adjust estimation equations of grass temperature from minimum air temperature. Temperature differences between the screen and grass were calculated and probability distributions of their occurrences were adjusted in order to determine risks per intervals of temperature differences. Estimation equations of grass temperature were adjusted from minimum screen temperatures. Average gradients of minimum temperature were observed between the screen and grass ranging from 4.2 to 6.3 °C in the analyzed regions. The average temperature difference measured in the meteorological screen and grass for the Paraná State was 5 °C. The probabilistic model of normal distribution is the most suitable for determining the probability of occurring the differences between the screen and grass temperatures for the Paraná State. Regional relief and climate conditions influence the magnitude of the minimum temperature gradient measured in the meteorological screen and grass. Estimation equations can be useful to determine the grass temperature based on the minimum air temperature for periods in which there is no such data and thus provide a subsidy for studies of risk analysis of frosts. The results of this analysis are empirical and the equations should be used in regions in which they were adjusted aiming at a higher accuracy.
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Bijl, Piet. "Triangle orientation discrimination: the alternative to minimum resolvable temperature difference and minimum resolvable contrast." Optical Engineering 37, no. 7 (1998): 1976. http://dx.doi.org/10.1117/1.601904.
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Blankert, Bastiaan, Johannes S. Vrouwenvelder, Geert-Jan Witkamp, and Noreddine Ghaffour. "Minimum Net Driving Temperature Concept for Membrane Distillation." Membranes 10, no. 5 (2020): 100. http://dx.doi.org/10.3390/membranes10050100.
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In this study, we analyzed the heat requirement of membrane distillation (MD) to investigate the trade-off between the evaporation efficiency and driving force efficiency in a single effect MD system. We found that there exists a non-zero net driving temperature difference that maximizes efficiency. This is the minimum net driving temperature difference necessary for a rational operational strategy because below the minimum net driving temperature, both the productivity and efficiency can be increased by increasing the temperature difference. The minimum net driving temperature has a similar magnitude to the boiling point elevation (~0.5 °C for seawater), and depends on the properties of the membrane and the heat exchanger. The minimum net driving temperature difference concept can be used to understand the occurrence of optimal values of other parameters, such as flux, membrane thickness, and membrane length, if these parameters are varied in a way that consequently varies the net driving temperature difference.
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Kolobrodov, V. G., N. I. Lykholit, and V. M. Tiagur. "Minimum resolvable temperature difference for thermal imager of space basing." Kosmìčna nauka ì tehnologìâ 20, no. 1(86) (2014): 23–27. http://dx.doi.org/10.15407/knit2014.01.023.
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Krapels, Keith, Ronald Driggers, Richard Vollmerhausen, and Carl Halford. "Minimum resolvable temperature difference (MRT): procedure improvements and dynamic MRT." Infrared Physics & Technology 43, no. 1 (2002): 17–31. http://dx.doi.org/10.1016/s1350-4495(01)00115-3.
Full textDissertations / Theses on the topic "Minimum temperature difference"
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Ugarte, Alejandro R. "Modeling for improved minimum resolvable temperature difference measurements." Thesis, Monterey, California. Naval Postgraduate School, 1991. http://hdl.handle.net/10945/28367.
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Approved for public release; distribution is unlimited<br>The minimum resolvable temperature difference (MRTD) is widely accepted as the parameter that best describes the field performance of a thermal imaging system (TIS). Mathematical modeling that accurately predicts the MRTD has been of major interest to the infrared community over the last 10 years. This work reviews the currently accepted models for predicting the MRTD. Simplifying assumptions used by these models which deal with target spectrum are discussed and tested using specifications taken from a standard forward looking infrared (FLIR) system. In addition new models are proposed and tested. Two of these models are a direct extension of the recently proposed Vortman-Bar-Lev adaptive matched filter. A third model is based on the novel concept that the MRTF curve is predictable from a threshold condition on the visibility, rather than the signal-to-noise ratio, of the system-degraded bar pattern.
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Guimarães, Edson F. C. "Investigation of minimum resolvable temperature difference formulation for polarized thermal imaging range prediction /." Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1999. http://handle.dtic.mil/100.2/ADA370908.
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Thesis (M.S. in Systems Engineering) Naval Postgraduate School, September 1999.<br>"September 1999". Thesis advisor(s): Alfred W. Cooper, Ron J. Pieper. Includes bibliographical references (p. 123-124). Also available online.
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Guimaraes, Edson F. C. "Investigation of minimum resolvable temperature difference formulation for polarized thermal imaging range prediction." Thesis, Monterey, California ; Naval Postgraduate School, 1999. http://hdl.handle.net/10945/13678.
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Previous measurements have demonstrated that a polarization filter can increase ship-background temperature contrast in the infrared, while decreasing the received radiance. Application of this technique to increasing range for detection or recognition of ship targets is being investigated through detection range modeling for a generic FLIR sensor. Laboratory measurements have been made of effective Minimum Resolvable Temperature Difference (MRTD) of a serial-scan 8-12 micrometers sensor for polarized and unpolarized radiation. A variety of standard four-bar target boards of varied spatial frequency and controlled bar-background temperature difference were used to construct MRTD vs. spatial frequency. Results were compared with model predictions using known or measured component parameters for the AGA-780 imager, showing close agreement for observations made by a "trained observer." A modified form of MRTD was developed for a polarized target using a reformulation of the thermal derivative of Planck's law. Modeled and measured values agreed closely for the unpolarized case, and also for both vertically and horizontally polarized cases when the appropriate parameters of the polarization filters were included. Mathematical analysis and measurement agreed in displaying an increase in MRTD with polarization. Predictions of maximum detection and recognition ranges using estimates of polarized effective target-background temperature difference indicated probable range improvement for sea surface degree of polarization in excess of 20%.
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Celik, Mustafa. "Measurements and modeling enhancements for the NPS Minimum Resolvable Temperature Difference Model, VISMODII /." Thesis, Monterey, California. Naval Postgraduate School, 2001. http://handle.dtic.mil/100.2/ADA397426.
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Groen, Michael S. "Development and validation of a second generation visibility-based model for predicting subjective and objective minimum resolvable temperature difference for staring thermal imaging systems." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1995. http://handle.dtic.mil/100.2/ADA305999.
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Thesis (M.S. in Electrical Engineering and M.S. in Applied Science) Naval Postgraduate School, December 1995.<br>Thesis advisor(s): Alfred W. Cooper, Ron J. Pieper. "December 1995." Cover title: Development ... temperature difference performance for staring ... Includes bibliographical references. Also available online.
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Quek, Yew Sing. "Characterization of 3-5 micron thermal imagers and analysis of narrow band images." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2004. http://library.nps.navy.mil/uhtbin/hyperion/04Dec%5FQuek.pdf.
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Thesis (M.S. in Combat Systems Technology)--Naval Postgraduate School, December 2004.<br>Thesis advisor(s): Alfred W.Cooper, Gamani Karunasiri. Includes bibliographical references (p. 91-92). Also available online.
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Ільченко, Марія Володимирівна. "Обґрунтування енергоефективних режимів роботи системи рекуперативних теплообмінників в процесі переробки піроконденсату". Thesis, НТУ "ХПІ", 2017. http://repository.kpi.kharkov.ua/handle/KhPI-Press/32636.
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Дисертація на здобуття наукового ступеня кандидата технічних наук за спеціальністю 05.17.08 – процеси та обладнання хімічної технології. – Національний технічний університет "Харківський політехнічний інститут" Міністерства освіти і науки України, Харків, 2017 р.
Дисертацію присвячено аналізу системи рекуперативного теплообміну і визначенню її недоліків для обґрунтування енергоефективних режимів роботи установки переробки піроконденсату з подальшим удосконаленням тепло- обмінної мережі. Проведено аналіз розвитку методології інтеграції процесів хімічних виробництв. Обґрунтовано необхідність застосування високоефективного пластинчастих теплообмінників на сучасних підприємствах задля максимальної економії енергоресурсів. Розглянуто тепловий розрахунок теплообмінника, принципи визначення середнього температурного напору і коефіцієнтів тепловіддачі. Досліджено можливість застосування відомих моделей перемішування, витіснення та їхньої комбінації при обрахунку теплообмінних апаратів. Наведено алгоритми розрахунку теплообмінників із робочими середовищами, що знаходяться в одній фазі та в різних. Представлено імітаційну модель переробки піроконденсату на установці виробництва бензолу, виконану за допомогою програмного забезпечення UniSim Design. Перевірено взаємне узгодження початкових даних та відзначено високу ступінь збіжності матеріальних і теплових балансів в отриманій розра-хунково-імітаційній моделі. Проведено аналіз функціонуючої теплообмінної системи, встановлено її недоліки та потенціал для енергозбереження. Екстраговано технологічні потоки та розраховано існуючу локалізацію пінчу зі встановленням значення мінімального температурного напору ΔTmin. Визначено локалізацію пінчу для можливої інтеграції. Розроблено три варіанти проектів реконструкції мережі теплообмінних апаратів із власними значеннями ΔTmin. Обчислено можливі техніко-економічні ефекти від запровадження проектів інтеграції у виробництво. Обрано найбільш економічно доцільний варіант проекту реконструкції системи теплообміну та запропоновано комплект теплообмінних апаратів із необхідними технічними характеристиками.<br>Thesis for granting the Degree of Candidate of Technical sciences in specialty 05.17.08 – processes and equipment of chemical technology – National Technical University "Kharkiv Polytechnic Institute" of Ministry of Education and Science of Ukraine, 2017.
The thesis is dedicated to the analysis of recuperative heat exchange system and determining its shortcomings for a substantiation of the energy efficient modes on pyrocondensate processing installation with further improvement of heat exchange network. The analysis of process integration methodology for chemical production is made. The necessity of the highly efficient plate heat exchangers for modern enterprises in order to maximize energy savings is substantiated. The thermal calculation of the heat exchanger, the principles of determining the average temperature pressure and the heat transfer coefficients are considered. The algorithms of the heat exchangers calculation with one-phase and two-phase working environments is provided. The simulation model of the process of pyrocondensate processing at the plant for the benzene production, performed using UniSim Design software, is presented. The mutual reconciliation of the initial data is checked and the high degree of material and thermal balances convergence in the resulting calculation-and-imitation model is noted. The analysis of the functioning heat exchange system is carried out, its deficiencies and energy saving potential are established. A number of technological streams are extracted and the existing pinch localization with determining of mini-mum temperature difference value ΔTmin are calculated. The pinch localization for possible process integration is determined. Three variants of reconstruction projects for the heat exchanger network, involved in the pyrocondensate processing, with their own optimum minimum temperature differ-ence values ΔTmin are developed. The most economically feasible variant of the heat exchange system reconstruction project is selected and a set of heat exchangers with the necessary technical characteristics are proposed.
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Ільченко, Марія Володимирівна. "Обґрунтування енергоефективних режимів роботи системи рекуперативних теплообмінників у процесі переробки піроконденсату". Thesis, НТУ "ХПІ", 2017. http://repository.kpi.kharkov.ua/handle/KhPI-Press/32632.
Full textAbstract:
Дисертація на здобуття наукового ступеня кандидата технічних наук за спеціальністю 05.17.08 – процеси та обладнання хімічної технології. – Національний технічний університет "Харківський політехнічний інститут" Міністерства освіти і науки України, Харків, 2017 р.
Дисертацію присвячено аналізу системи рекуперативного теплообміну і визначенню її недоліків для обґрунтування енергоефективних режимів роботи установки переробки піроконденсату з подальшим удосконаленням тепло- обмінної мережі. Проведено аналіз розвитку методології інтеграції процесів хімічних виробництв. Обґрунтовано необхідність застосування високоефективного пластинчастих теплообмінників на сучасних підприємствах задля максимальної економії енергоресурсів. Розглянуто тепловий розрахунок теплообмінника, принципи визначення середнього температурного напору і коефіцієнтів тепловіддачі. Досліджено можливість застосування відомих моделей перемішування, витіснення та їхньої комбінації при обрахунку теплообмінних апаратів. Наведено алгоритми розрахунку теплообмінників із робочими середовищами, що знаходяться в одній фазі та в різних. Представлено імітаційну модель переробки піроконденсату на установці виробництва бензолу, виконану за допомогою програмного забезпечення UniSim Design. Перевірено взаємне узгодження початкових даних та відзначено високу ступінь збіжності матеріальних і теплових балансів в отриманій розра-хунково-імітаційній моделі. Проведено аналіз функціонуючої теплообмінної системи, встановлено її недоліки та потенціал для енергозбереження. Екстраговано технологічні потоки та розраховано існуючу локалізацію пінчу зі встановленням значення мінімального температурного напору ΔTmin. Визначено локалізацію пінчу для можливої інтеграції. Розроблено три варіанти проектів реконструкції мережі теплообмінних апаратів із власними значеннями ΔTmin. Обчислено можливі техніко-економічні ефекти від запровадження проектів інтеграції у виробництво. Обрано найбільш економічно доцільний варіант проекту реконструкції системи теплообміну та запропоновано комплект теплообмінних апаратів із необхідними технічними характеристиками.<br>Thesis for granting the Degree of Candidate of Technical sciences in specialty 05.17.08 – processes and equipment of chemical technology – National Technical University "Kharkiv Polytechnic Institute" of Ministry of Education and Science of Ukraine, 2017.
The thesis is dedicated to the analysis of recuperative heat exchange system and determining its shortcomings for a substantiation of the energy efficient modes on pyrocondensate processing installation with further improvement of heat exchange network. The analysis of process integration methodology for chemical production is made. The necessity of the highly efficient plate heat exchangers for modern enterprises in order to maximize energy savings is substantiated. The thermal calculation of the heat exchanger, the principles of determining the average temperature pressure and the heat transfer coefficients are considered. The algorithms of the heat exchangers calculation with one-phase and two-phase working environments is provided. The simulation model of the process of pyrocondensate processing at the plant for the benzene production, performed using UniSim Design software, is presented. The mutual reconciliation of the initial data is checked and the high degree of material and thermal balances convergence in the resulting calculation-and-imitation model is noted. The analysis of the functioning heat exchange system is carried out, its deficiencies and energy saving potential are established. A number of technological streams are extracted and the existing pinch localization with determining of mini-mum temperature difference value ΔTmin are calculated. The pinch localization for possible process integration is determined. Three variants of reconstruction projects for the heat exchanger network, involved in the pyrocondensate processing, with their own optimum minimum temperature differ-ence values ΔTmin are developed. The most economically feasible variant of the heat exchange system reconstruction project is selected and a set of heat exchangers with the necessary technical characteristics are proposed.
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Lai, Hsiang-Cheng, and 賴享承. "Minimum skew clock tree in 3D IC under different temperatures." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/06791222913548188251.
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碩士<br>中原大學<br>資訊工程研究所<br>100<br>3D IC integration of circuit is a promising approach to integrate large systems on a single chip. The average global wirelength is reduced drastically. But the thermal can not dissipate efficiently in 3D ICs, because each chips are stacked in vertical direction. The temperature in 3D ICs increase drastically. Therefore, how to construct a minimal skew clock tree considering the temperature distribution is becoming an important issue.
In this parper, we proposed a 3D clock tree generator that the skew under worst case temperature profile and uniform temperature profile are nearly equal. Experimental results show that our algorithms significantly reduce the skew and balance clock skew values under different temperature profiles.
First, we import the temperature distribution of a chip before we construct the clock tree. We build sink relation by Delay-based Sink Relation Graph algorithm, and choose smaller delay by Delay-based Grouping. We will calculate the precise position of Merging Segments according to the temperature at each tile. Finally, we build up the thermal-aware clock tree in top down phase with the information of the topology.
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谷川, 恭雄, 博嗣 森, 善幸 黒川, 洋一 新井, 豊. 笠井 та 良平 野田. "建物外壁仕上げ材の剥離診断のためのサ-モグラフィ-法の標準化に関する研究". 1995. http://hdl.handle.net/2237/13017.
Full textBooks on the topic "Minimum temperature difference"
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Ugarte, Alejandro R. Modeling for improved minimum resolvable temperature difference measurements. Naval Postgraduate School, 1991.
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2
Investigation of Minimum Resolvable Temperature Difference Formulation for Polarized Thermal Imaging Range Prediction. Storming Media, 1999.
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3
Measurements and Modeling Enhancements for the NPS Minimum Resolvable Temperature Difference Model, VISMODII. Storming Media, 2001.
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Christensen, Ole Bøssing, and Erik Kjellström. Projections for Temperature, Precipitation, Wind, and Snow in the Baltic Sea Region until 2100. Oxford University Press, 2018. http://dx.doi.org/10.1093/acrefore/9780190228620.013.695.
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The ecosystems and the societies of the Baltic Sea region are quite sensitive to fluctuations in climate, and therefore it is expected that anthropogenic climate change will affect the region considerably. With numerical climate models, a large amount of projections of meteorological variables affected by anthropogenic climate change have been performed in the Baltic Sea region for periods reaching the end of this century.Existing global and regional climate model studies suggest that:• The future Baltic climate will get warmer, mostly so in winter. Changes increase with time or increasing emissions of greenhouse gases. There is a large spread between different models, but they all project warming. In the northern part of the region, temperature change will be higher than the global average warming.• Daily minimum temperatures will increase more than average temperature, particularly in winter.• Future average precipitation amounts will be larger than today. The relative increase is largest in winter. In summer, increases in the far north and decreases in the south are seen in most simulations. In the intermediate region, the sign of change is uncertain.• Precipitation extremes are expected to increase, though with a higher degree of uncertainty in magnitude compared to projected changes in temperature extremes.• Future changes in wind speed are highly dependent on changes in the large-scale circulation simulated by global climate models (GCMs). The results do not all agree, and it is not possible to assess whether there will be a general increase or decrease in wind speed in the future.• Only very small high-altitude mountain areas in a few simulations are projected to experience a reduction in winter snow amount of less than 50%. The southern half of the Baltic Sea region is projected to experience significant reductions in snow amount, with median reductions of around 75%.
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Liu, Xiaodong, and Libin Yan. Elevation-Dependent Climate Change in the Tibetan Plateau. Oxford University Press, 2017. http://dx.doi.org/10.1093/acrefore/9780190228620.013.593.
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As a unique and high gigantic plateau, the Tibetan Plateau (TP) is sensitive and vulnerable to global climate change, and its climate change tendencies and the corresponding impact on regional ecosystems and water resources can provide an early alarm for global and mid-latitude climate changes. Growing evidence suggests that the TP has experienced more significant warming than its surrounding areas during past decades, especially at elevations higher than 4 km. Greater warming at higher elevations than at lower elevations has been reported in several major mountainous regions on earth, and this interesting phenomenon is known as elevation-dependent climate change, or elevation-dependent warming (EDW).At the beginning of the 21st century, Chinese scholars first noticed that the TP had experienced significant warming since the mid-1950s, especially in winter, and that the latest warming period in the TP occurred earlier than enhanced global warming since the 1970s. The Chinese also first reported that the warming rates increased with the elevation in the TP and its neighborhood, and the TP was one of the most sensitive areas to global climate change. Later, additional studies, using more and longer observations from meteorological stations and satellites, shed light on the detailed characteristics of EDW in terms of mean, minimum, and maximum temperatures and in different seasons. For example, it was found that the daily minimum temperature showed the most evident EDW in comparison to the mean and daily maximum temperatures, and EDW is more significant in winter than in other seasons. The mean daily minimum and maximum temperatures also maintained increasing trends in the context of EDW. Despite a global warming hiatus since the turn of the 21st century, the TP exhibited persistent warming from 2001 to 2012.Although EDW has been demonstrated by more and more observations and modeling studies, the underlying mechanisms for EDW are not entirely clear owing to sparse, discontinuous, and insufficient observations of climate change processes. Based on limited observations and model simulations, several factors and their combinations have been proposed to be responsible for EDW, including the snow-albedo feedback, cloud-radiation effects, water vapor and radiative fluxes, and aerosols forcing. At present, however, various explanations of the mechanisms for EDW are mainly derived from model-based research, lacking more solid observational evidence. Therefore, to comprehensively understand the mechanisms of EDW, a more extensive and multiple-perspective climate monitoring system is urgently needed in the areas of the TP with high elevations and complex terrains.High-elevation climate change may have resulted in a series of environmental consequences, such as vegetation changes, permafrost melting, and glacier shrinkage, in mountainous areas. In particular, the glacial retreat could alter the headwater environments on the TP and the hydrometeorological characteristics of several major rivers in Asia, threatening the water supply for the people living in the adjacent countries. Taking into account the climate-model projections that the warming trend will continue over the TP in the coming decades, this region’s climate change and the relevant environmental consequences should be of great concern to both scientists and the general public.
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Mast, Christof, Friederike Möller, Moritz Kreysing, et al. Toward living nanomachines. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780199674923.003.0039.
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How does inanimate matter become transformed into animate matter? Living systems evolve by replication and selection at the molecular level and this chapter considers how to establish a synthetic, minimal system that can support molecular evolution and thus life. Molecular evolution cannot be explained by starting with high concentrations of activated chemicals that react toward their chemical equilibrium; persistent non-equilibria are required to maintain continuous reactivity and we especially consider thermal gradients as an early driving force for Darwinian molecular evolution. The temperature difference across water-filled compartments implements a laminar fluid convection with periodic temperature oscillations that allow for the melting and replication of DNA. Simultaneously, dissolved molecules are moved along the thermal gradient by an effect called thermophoresis. The combined result is an efficient molecule trap that exponentially favors long over short DNA and thus maintains complexity. Future experiments will reveal how thermal gradients could actively drive the Darwinian process of replication and selection.
Book chapters on the topic "Minimum temperature difference"
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Tesfaye, Argaw, and Arragaw Alemayehu. "Climate Change and Variability on Food Security of Rural Household: Central Highlands, Ethiopia." In African Handbook of Climate Change Adaptation. Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-45106-6_188.
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AbstractThis chapter analyzes the impact of climate change and variability on food security of rural households in the central highlands of Ethiopia taking Basona Werana district as a case study site. Data were obtained from 123 households selected using simple random sampling from three agro ecological zones. Key informant interviews and focus group discussion (FDG) were used to supplement the data obtained from household survey. The monthly rainfall and temperature data are for 56 points of 10 × 10 km grids reconstructed from weather stations and meteorological satellite observations, which cover the period between 1983 and 2016. Standardized rainfall anomaly (SRA), linear regression (LR), and coefficient of variation (CV) are used to examine inter-annual and intra-annual variability of rainfall. Annual and seasonal rainfalls show decreasing trends over the period of observation. The decreasing trends in annual and March–May (Belg) rainfall totals exhibit statically significant decreasing trends at p = 0.05 level. Kiremt (June–September) shows statically significant decreasing trends at p = 0.1 level. Mean annual maximum and minimum temperatures show statically significant increasing trends at p = 0.05 level. More than 80% of households perceived that the climate is changing and their livelihoods (crop and livestock production) are impacted. The district belongs to one of the most vulnerable areas to climate change and variability in the country where large proportions of households (62%) are under different food insecurity classes. Results suggest that local level investigations are useful in developing context-specific climate change adaptation.
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Mbwambo, Naza A., and Emma T. Liwenga. "Cassava as an adaptation crop to climate variability and change in coastal areas of Tanzania: a case of the Mkuranga district." In Climate change impacts and sustainability: ecosystems of Tanzania. CABI, 2020. http://dx.doi.org/10.1079/9781789242966.0023.
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Abstract This study was carried out in two villages, Kizapala and Kazole, of the Mkuranga District, in the Coast Region of Tanzania. The objective of the study was to establish the role of cassava as an adaptation crop to the changing climate and household food security. Primary data were obtained using household questionnaires and different participatory rural appraisal (PRA) techniques which included focus group discussions (FGDs), key informants and expert meetings. Secondary data were collected through a literature review, whereas temperature and rainfall data from 1984 to 2014 was obtained from the Tanzania Meteorological Agency (TMA). In each village, a sample size of 10% of all households was interviewed. Findings showed that 96% of respondents from Kazole village and 90% from Kizapala linked climate change with major climatic extreme events such as prolonged droughts and occasional abnormal floods. Analysis of temperature data for the last 30 years (1984-2014) revealed that temperature had significantly risen by a correlation coefficient of R<sup>2</sup> = 0.4936 for maximum and R<sup>2</sup> = 0.777 for minimum temperature. The field survey results closely correlated with findings from the analysis of TMA rainfall and temperature data. Findings revealed a decline in crop production which resulted in food shortages and livelihood insecurity in the study villages. The respondents in both villages consider cassava as a crop that is least affected by climate and environmental extremes, thus serves to ensure food availability and security in their households. As a result, growing cassava should be considered as an adaptation strategy to climate change and variability now and in the future. Improving cassava production, processing, marketing and value chain infrastructures is, therefore, crucial for enhancing sustainable adaptation in the district.
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Hussain, Manzoor, Ljupcho Jankuloski, M. Habib-ur-Rahman, et al. "Improving sustainable cotton production through enhanced resilience to climate change using mutation breeding." In Mutation breeding, genetic diversity and crop adaptation to climate change. CABI, 2021. http://dx.doi.org/10.1079/9781789249095.0015.
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Abstract Cotton, being a leading commercial fibre crop, is grown on 20.5 million hectares in three major cotton-producing countries: China, India and Pakistan. Wide differences in yield per hectare exist among these countries and these are being aggravated by changing climate conditions, i.e. higher temperatures and significant seasonal and regional fluctuation in rainfall. Pakistan is one of the countries most affected by climate change. The disastrous effects of extreme periods of heat stress in cotton were very prominent in Pakistan during the growing seasons 2013-2014 (40-50% fruit abortion) and 2016-2017 (33% shortfall), which posed an alarming threat to the cotton-based economy of Pakistan. Poor resilience of the most commonly grown cotton varieties against extreme periods of heat stress are considered to be major factors for this drastic downfall in cotton production in Pakistan. Using the approach of induced mutation breeding, the Nuclear Institute for Agriculture and Biology (NIAB), Faisalabad, Pakistan, has demonstrated its capabilities in developing cotton mutants that can tolerate the changed climatic conditions and sustain high yields under contrasting environments. The results of studies on the phenological and physiological traits conferring heat tolerance are presented here for thermo-tolerant cotton mutants (NIAB-878, NIAB-545, NIAB-1048, NIAB-444, NIAB-1089, NIAB-1064, NIAB-1042) relative to FH-142 and FH-Lalazar. NIAB-878 excelled in heat tolerance by maintaining the highest anther dehiscence (82%) and minimum cell injury percentage (39%) along with maximum stomatal conductance (27.7 mmol CO<sub>2</sub>/m<sup>2</sup>/s), transpiration rate (6.89 μmol H<sub>2</sub>O/m<sup>2</sup>/s), net photosynthetic rate (44.6 mmol CO<sub>2</sub>/m<sup>2</sup>/s) and physiological water use efficiency (6.81 mmol CO<sub>2</sub>/μmol H<sub>2</sub>O) under the prevailing high temperatures.
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Sahli, Youcef, Bariza Zitouni, and Ben Moussa Hocine. "Three-Dimensional Numerical Study of Overheating of Two Intermediate Temperature P-AS-SOFC Geometrical Configurations." In Hydrogen Fuel Cell Technology for Stationary Applications. IGI Global, 2021. http://dx.doi.org/10.4018/978-1-7998-4945-2.ch008.
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The purpose of this work is to perform a three-dimensional and stationary numerical study of the heat transfer phenomenon in the planar anode-supported solid oxide fuel cells operating at intermediate temperature (IT-P-AS-SOFC). With particular interest to evaluate and localize the maximum and minimum temperatures in a single cell during their stable operation according to two geometrical configuration types, repetition, and symmetry of the cell stages to determine the best configuration that minimizes and produces more homogeneous thermal stresses and logically improves their lifetime and performance. The considered heat sources are mainly due to electrical overpotentials (Ohm, activation, and concentration). The results are obtained according to a FORTRAN code based on the proposed model that is numerically modeled using the finite difference method. From the obtained result analysis, the achieved temperature values by IT-P-AS-SOFC with cell stages repetition are greater than obtained by IT-P-AS-SOFC with cell stages symmetry.
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Shinde, Dinesh S., Ashnut Dutt, Ranjan Kumar Ghadai, Kanak Kalita, and Amer Nasr A. Elghaffar. "Evaluation of Optimum Parameters for Casting of Birla Lance Pipes." In Advances in Civil and Industrial Engineering. IGI Global, 2021. http://dx.doi.org/10.4018/978-1-7998-7206-1.ch002.
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Defects associated with casting of pipes are often a main concern for the industry. In this chapter, a Taguchi analysis is carried out to understand the effect of three process parameter pouring temperature (°C), die spinning speed (rpm), and coolant flow time (mins) on the casting defect of pipes. The defect is defined in this work as the difference between the desired thickness of the pipe and the minimum actual (experimentally) achieved. A L9 orthogonal array is designed to carry out the experiments. Based on the S/N ratio analysis and ANOVA, it is seen that the die spinning speed plays the most critical role in defect of the pipes. As per the conducted experiments and Taguchi analysis, pouring temperature is seen to have the lest influence on the defects.
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Sami Abourayya, Mahmoud, and E. K. Nabila. "Expansion in Cultivating Almond Trees in Egypt." In Prunus - Recent Advances [Working Title]. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.98618.
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Egypt spends a lot of hard currency annually to import nut fruits (almond- walnut and pistachio) to apply market needs of these crops especially in Ramadan month. It is known that there are wide uncultivated areas in Sinai despite of its suitability for cultivation. Cultivating nut trees can share in development of Sinai. There are scarcity of these trees in Egypt in spite of the relevance of environmental conditions for growing almond trees in different regions. Since the last 25 years I and a group of scientists studied the possibility of achieving self sufficiency of almond by cultivating in Sinai Peninsula and different regions after carrying out climatic, economical, water requirements, nutrition and genetic studies. Many fruit trees require cold temperatures during the winter to overcome their seasonal dormancy.() Most fruit species that evolved in temperate or cool subtropical climates have such chilling requirements that need to be fulfilled each winter to achieve homogeneous and simultaneous flowering and regular crop yields. Coldness. (). Monthly historical data of minimum temperature from Central laborator for Agricultural climate of four districts were analyzed in order to determine the changes in minimum temperature from October to February during the period from 2001 to 2010. Understanding monthly temperature changes from October to February during the period 2001–2010 was the first step in carrying out this study. The highest minimum temperature was found during 2010 year during the studied period in the October month for all districts except in November and December, the highest minimum temperature was observed in the year of 2009. Saint Catherine district was the lowest minimum temperature in all months during the studied period. Understanding average monthly temperature trends of the studied time serious from 2001 to 2010 was the second step in carrying out this study. October month was the highest values of minimum temperature and January was the lowest value of minimum temperature at the four districts. The highest and lowest values for temperature were found in Ras Sudr and Saint Catherine respectively. The third step in carrying out this study is to understanding the annual trend of minimum temperature for the period 2001–2010 at the Suez, Ras Sudr, El Tur and Saint Catherine districts. Data shows the average annual minimum temperature at the four districts during the years from 2001 up to 2010 and it can be observed that, Ras Sudr district has the highest average annual minimum temperature while Saint Catherine has the lowest one among the studied districts. It can be concluded that the carried out climatic studies, estimate the irrigation water requirements of almond trees and genetic studies help in solving the problem of achieving self sufficiency of almond fruits through expansion of cultivating almond trees in Egypt.
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Kousky, Vernon E., and Gerald D. Bell. "Causes, Predictions, and Outcomes of El Niño 1997-1998." In El Niño, 1997-1998. Oxford University Press, 2000. http://dx.doi.org/10.1093/oso/9780195135510.003.0008.
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One of the most prominent aspects of our weather and climate is its variability. This variability ranges over many time and space scales, from small-scale weather phenomena such as wind gusts, localized thunderstorms, and tornadoes, to larger-scale weather features such as fronts and storms and to prolonged climate features such as droughts, floods, and fluctuations occurring on multiseasonal, multiyear, and multidecade time scales. Some examples of these longer time-scale fluctuations include abnormally hot and dry summers, abnormally cold and snowy winters, a series of abnormally mild or exceptionally severe winters, and even a mild winter followed by a severe winter. In general, the longer time-scale variations are often associated with changes in the atmospheric circulation that encompass areas far larger than a particular affected region. At times, these persistent circulation features affect vast parts of the globe, resulting in abnormal temperature and precipitation patterns in many areas. During the past several decades, scientists have discovered that important aspects of interannual variability in global weather patterns are linked to a naturally occurring phenomenon known as the El Niño / Southern Oscillation (ENSO) cycle. The heart of ENSO lies in the tropical Pacific, where there is strong coupling between variations in ocean surface temperatures and the circulation of the overlying atmosphere. The terms El Niño and La Niña represent opposite extremes of the ENSO cycle, and they cause very different rainfall outcomes, as illustrated in Figure 2-1. Before describing the oceanic and atmospheric characteristics of the ENSO cycle, it is necessary to describe the average climatic conditions and how they vary throughout the year. Interannual climate variability is often measured by comparing the observed conditions to the long-term mean conditions. The mean state of the tropical Pacific Ocean is identified by both its surface and its subsurface characteristics, each of which exhibits considerable evolution across the eastern half of the tropical Pacific during the course of the year. Throughout the year, the ocean surface is warmest in the west and coldest in the east. The largest difference between the two regions is observed during September and October, when temperatures in the eastern Pacific reach their annual minimum.
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"Machining Mechanism of Minimum Quantity Lubrication Grinding." In Enhanced Heat Transfer Mechanism of Nanofluid MQL Cooling Grinding. IGI Global, 2020. http://dx.doi.org/10.4018/978-1-7998-1546-4.ch003.
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To facilitate the analysis of experimental theory, this chapter studied the machining mechanism related to the grinding of NMQL and the three mechanisms of sliding, ploughing, and cutting of the abrasive grinding process. A mathematical model of the micro-grinding force was established, and the micro-grinding force can be used to express the force of the grinding zone. The grinding force component was divided into the force of cutting and sliding, removing the constant cutting force during the grinding process, retaining the varying sliding friction force, and determining the sliding friction coefficient to characterize the lubrication performance. It reflected the influence of different lubrication conditions on the friction part. The methods for measuring the temperature during grinding were introduced, including direct contact temperature measurement and non-contact temperature measurement. At present, thermocouple temperature measurement is a commonly used and more accurate temperature measurement method, and the characteristics of each temperature measurement method were analyzed.
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"Experimental Research on Heat Transfer Performance in MQL Grinding With Different Nanofluids." In Enhanced Heat Transfer Mechanism of Nanofluid MQL Cooling Grinding. IGI Global, 2020. http://dx.doi.org/10.4018/978-1-7998-1546-4.ch008.
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An investigation into the effect of nanofluid minimum quantity lubrication (MQL) on the temperatures in surface grinding is presented and discussed. Six types of nanoparticles, namely molybdenum disulfide (MoS2), zirconium dioxide (ZrO2), carbon nanotube (CNT), polycrystalline diamond, aluminum oxide (Al2O3), and silica dioxide (SiO2), are considered to mix individually with a pollution-free palm oil in preparing the nanofluids. A commonly used Ni-based alloy was chosen as the workpiece material. It is shown that CNT nanofluid results in the lowest grinding temperature of 110.7°C and the associated energy proportionality coefficient of 40.1%. The relevant physical properties of the nanofluids such as the coefficient of thermal conductivity, viscosity, surface tension, and the contact state between the droplets and workpiece surface (contact angle) were discussed to shine a light on their effect on the cooling performance. A mathematical model for convective heat transfer coefficient was then developed based on the boundary layer theories.
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Li, Changhe, and Hafiz Muhammad Ali. "Experimental Research on Heat Transfer Performance in MQL Grinding With Different Nanofluids." In Research Anthology on Synthesis, Characterization, and Applications of Nanomaterials. IGI Global, 2021. http://dx.doi.org/10.4018/978-1-7998-8591-7.ch042.
Full textAbstract:
An investigation into the effect of nanofluid minimum quantity lubrication (MQL) on the temperatures in surface grinding is presented and discussed. Six types of nanoparticles, namely molybdenum disulfide (MoS2), zirconium dioxide (ZrO2), carbon nanotube (CNT), polycrystalline diamond, aluminum oxide (Al2O3), and silica dioxide (SiO2), are considered to mix individually with a pollution-free palm oil in preparing the nanofluids. A commonly used Ni-based alloy was chosen as the workpiece material. It is shown that CNT nanofluid results in the lowest grinding temperature of 110.7°C and the associated energy proportionality coefficient of 40.1%. The relevant physical properties of the nanofluids such as the coefficient of thermal conductivity, viscosity, surface tension, and the contact state between the droplets and workpiece surface (contact angle) were discussed to shine a light on their effect on the cooling performance. A mathematical model for convective heat transfer coefficient was then developed based on the boundary layer theories.
Conference papers on the topic "Minimum temperature difference"
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D'Agostino, John A., and J. R. Moulton. "Minimum findable temperature difference." In SPIE's International Symposium on Optical Engineering and Photonics in Aerospace Sensing, edited by Gerald C. Holst. SPIE, 1994. http://dx.doi.org/10.1117/12.180089.
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Bendall, Charles S. "Automated objective minimum resolvable temperature difference." In AeroSense 2000, edited by Gerald C. Holst. SPIE, 2000. http://dx.doi.org/10.1117/12.391788.
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Webb, Curtis M., and Gerald C. Holst. "Observer variables in minimum-resolvable temperature difference." In Aerospace Sensing, edited by Gerald C. Holst. SPIE, 1992. http://dx.doi.org/10.1117/12.137965.
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Sousk, Stephen F., Patrick D. O'Shea, and Van A. Hodgkin. "Uncertainties in the minimum resolvable temperature difference measurement." In Defense and Security, edited by Gerald C. Holst. SPIE, 2004. http://dx.doi.org/10.1117/12.541352.
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Pieper, Ronald J., and Alfred W. Cooper. "Visibility model for minimum resolvable temperature difference prediction." In SPIE's International Symposium on Optical Engineering and Photonics in Aerospace Sensing, edited by Gerald C. Holst. SPIE, 1994. http://dx.doi.org/10.1117/12.180077.
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Driggers, Ronald G., Van A. Hodgkin, Richard H. Vollmerhausen, and Patrick O'Shea. "Minimum resolvable temperature difference measurements on undersampled imagers." In AeroSense 2003, edited by Gerald C. Holst. SPIE, 2003. http://dx.doi.org/10.1117/12.487065.
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Kennedy, Howard V. "Recognition criterion for two-dimensional minimum resolvable temperature difference." In Orlando '91, Orlando, FL, edited by Gerald C. Holst. SPIE, 1991. http://dx.doi.org/10.1117/12.45802.
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Webb, Curtis M. "Minimum resolvable temperature difference--how far can we stretch it?" In SPIE's International Symposium on Optical Engineering and Photonics in Aerospace Sensing, edited by Gerald C. Holst. SPIE, 1994. http://dx.doi.org/10.1117/12.180068.
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Kolobrodov, V. G., and V. I. Mykytenko. "Refinement of thermal imager minimum resolvable temperature difference calculating method." In 12th International Conference on Correlation Optics, edited by Oleg V. Angelsky. SPIE, 2015. http://dx.doi.org/10.1117/12.2228532.
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Braddick, Roger C., and J. H. Ludlow. "Novel GO-NO GO minimum resolvable temperature difference tester and its development." In SPIE's International Symposium on Optical Engineering and Photonics in Aerospace Sensing, edited by Gerald C. Holst. SPIE, 1994. http://dx.doi.org/10.1117/12.180067.
Full textReports on the topic "Minimum temperature difference"
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Ruosteenoja, Kimmo. Applicability of CMIP6 models for building climate projections for northern Europe. Finnish Meteorological Institute, 2021. http://dx.doi.org/10.35614/isbn.9789523361416.
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In this report, we have evaluated the performance of nearly 40 global climate models (GCMs) participating in Phase 6 of the Coupled Model Intercomparison Project (CMIP6). The focus is on the northern European area, but the ability to simulate southern European and global climate is discussed as well. Model evaluation was started with a technical control; completely unrealistic values in the GCM output files were identified by seeking the absolute minimum and maximum values. In this stage, one GCM was rejected totally, and furthermore individual output files from two other GCMs. In evaluating the remaining GCMs, the primary tool was the Model Climate Performance Index (MCPI) that combines RMS errors calculated for the different climate variables into one index. The index takes into account both the seasonal and spatial variations in climatological means. Here, MCPI was calculated for the period 1981—2010 by comparing GCM output with the ERA-Interim reanalyses. Climate variables explored in the evaluation were the surface air temperature, precipitation, sea level air pressure and incoming solar radiation at the surface. Besides MCPI, we studied RMS errors in the seasonal course of the spatial means by examining each climate variable separately. Furthermore, the evaluation procedure considered model performance in simulating past trends in the global-mean temperature, the compatibility of future responses to different greenhouse-gas scenarios and the number of available scenario runs. Daily minimum and maximum temperatures were likewise explored in a qualitative sense, but owing to the non-existence of data from multiple GCMs, these variables were not incorporated in the quantitative validation. Four of the 37 GCMs that had passed the initial technical check were regarded as wholly unusable for scenario calculations: in two GCMs the responses to the different greenhouse gas scenarios were contradictory and in two other GCMs data were missing from one of the four key climate variables. Moreover, to reduce inter-GCM dependencies, no more than two variants of any individual GCM were included; this led to an abandonment of one GCM. The remaining 32 GCMs were divided into three quality classes according to the assessed performance. The users of model data can utilize this grading to select a subset of GCMs to be used in elaborating climate projections for Finland or adjacent areas. Annual-mean temperature and precipitation projections for Finland proved to be nearly identical regardless of whether they were derived from the entire ensemble or by ignoring models that had obtained the lowest scores. Solar radiation projections were somewhat more sensitive.
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Firon, Nurit, Prem Chourey, Etan Pressman, Allen Hartwell, and Kenneth J. Boote. Molecular Identification and Characterization of Heat-Stress-Responsive Microgametogenesis Genes in Tomato and Sorghum - A Feasibility Study. United States Department of Agriculture, 2007. http://dx.doi.org/10.32747/2007.7591741.bard.
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Exposure to higher than optimal temperatures - heat-stress (HS) - is becoming increasingly common to all crop plants worldwide. Heat stress coinciding with microgametogenesis, especially during the post-meiotic phase that is marked by starch biosynthesis, is often associated with starch-deficient pollen and male sterility and ultimately, greatly reduced crop yields. The molecular basis for the high sensitivity of developing pollen grains, on one hand, and factors involved in pollen heat-tolerance, on the other, is poorly understood. The long-term goal of this project is to provide a better understanding of the genes that control pollen quality under heat-stress conditions. The specific objectives of this project were: (1) Determination of the threshold heat stress temperature(s) that affects tomato and sorghum pollen quality whether: a) Chronic mild heat stress conditions (CMHS), or b) Acute heat stress (AHS). (2) Isolation of heat-responsive, microgametogenesis-specific sequences. During our one-year feasibility project, we have accomplished the proposed objectives as follows: Objectrive 1: We have determined the threshold HS conditions in tomato and sorghum. This was essential for achieving the 2nd objective, since our accumulated experience (both Israeli and US labs) indicate that when temperature is raised too high above "threshold HS levels" it may cause massive death of the developing pollen grains. Above-threshold conditions have additional major disadvantages including the "noise" caused by induced expression of genes involved in cell death and masking of the differences between heatsensitive and heat-tolerant pollen grains. Two different types of HS conditions were determined: a) Season-long CMHS conditions: 32/26°C day/night temperatures confirmed in tomato and 36/26°C day maximum/night minimum temperatures in sorghum. b) Short-term AHS: In tomato, 2 hour exposure to 42-45°C (at 7 to 3 days before anthesis) followed by transfer to 28/22±2oC day/night temperatures until flower opening and pollen maturation, caused 50% reduced germinating pollen in the heat-sensitive 3017 cv.. In sorghum, 36/26°C day/night temperatures 10 to 5 days prior to panicle emergence, occurring at 35 days after sowing (DAS) in cv. DeKalb28E, produced starch-deficient and sterile pollen. Objective 2: We have established protocols for the high throughput transcriptomic approach, cDNA-AFLP, for identifying and isolating genes exhibiting differential expression in developing microspores exposed to either ambient or HS conditions and created a databank of HS-responsivemicrogametogenesis-expressed genes. A subset of differentially displayed Transcript-Derived Fragments (TDFs) that were cloned and sequenced (35 & 23 TDFs in tomato and sorghum, respectively) show close sequence similarities with metabolic genes, genes involved in regulation of carbohydrate metabolism, genes implicated in thermotolerance (heat shock proteins), genes involved in long chain fatty acids elongation, genes involved in proteolysis, in oxidation-reduction, vesicle-mediated transport, cell division and transcription factors. T-DNA-tagged Arabidopsis mutants for part of these genes were obtained to be used for their functional analysis. These studies are planned for a continuation project. Following functional analyses of these genes under HS – a valuable resource of genes, engaged in the HS-response of developing pollen grains, that could be modulated for the improvement of pollen quality under HS in both dicots and monocots and/or used to look for natural variability of such genes for selecting heat-tolerant germplasm - is expected.
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Quinn, Meghan. Geotechnical effects on fiber optic distributed acoustic sensing performance. Engineer Research and Development Center (U.S.), 2021. http://dx.doi.org/10.21079/11681/41325.
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Distributed Acoustic Sensing (DAS) is a fiber optic sensing system that is used for vibration monitoring. At a minimum, DAS is composed of a fiber optic cable and an optic analyzer called an interrogator. The oil and gas industry has used DAS for over a decade to monitor infrastructure such as pipelines for leaks, and in recent years changes in DAS performance over time have been observed for DAS arrays that are buried in the ground. This dissertation investigates the effect that soil type, soil temperature, soil moisture, time in-situ, and vehicle loading have on DAS performance for fiber optic cables buried in soil. This was accomplished through a field testing program involving two newly installed DAS arrays. For the first installation, a new portion of DAS array was added to an existing DAS array installed a decade prior. The new portion of the DAS array was installed in four different soil types: native fill, sand, gravel, and an excavatable flowable fill. Soil moisture and temperature sensors were buried adjacent to the fiber optic cable to monitor seasonal environmental changes over time. Periodic impact testing was performed at set locations along the DAS array for over one year. A second, temporary DAS array was installed to test the effect of vehicle loading on DAS performance. Signal to Noise Ratio (SNR) of the DAS response was used for all the tests to evaluate the system performance. The results of the impact testing program indicated that the portions of the array in gravel performed more consistently over time. Changes in soil moisture or soil temperature did not appear to affect DAS performance. The results also indicated that time DAS performance does change somewhat over time. Performance variance increased in new portions of array in all material types through time. The SNR in portions of the DAS array in native silty sand material dropped slightly, while the SNR in portions of the array in sand fill and flowable fill material decreased significantly over time. This significant change in performance occurred while testing halted from March 2020 to August 2020 due to the Covid-19 pandemic. These significant changes in performance were observed in the new portion of test bed, while the performance of the prior installation remained consistent. It may be that, after some time in-situ, SNR in a DAS array will reach a steady state. Though it is unfortunate that testing was on pause while changes in DAS performance developed, the observed changes emphasize the potential of DAS to be used for infrastructure change-detection monitoring. In the temporary test bed, increasing vehicle loads were observed to increase DAS performance, although there was considerable variability in the measured SNR. The significant variation in DAS response is likely due to various industrial activities on-site and some disturbance to the array while on-boarding and off-boarding vehicles. The results of this experiment indicated that the presence of load on less than 10% of an array channel length may improve DAS performance. Overall, this dissertation provides guidance that can help inform the civil engineering community with respect to installation design recommendations related to DAS used for infrastructure monitoring.
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Lers, Amnon, Majid R. Foolad, and Haya Friedman. genetic basis for postharvest chilling tolerance in tomato fruit. United States Department of Agriculture, 2014. http://dx.doi.org/10.32747/2014.7600014.bard.
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ABSTRACT Postharvest losses of fresh produce are estimated globally to be around 30%. Reducing these losses is considered a major solution to ensure global food security. Storage at low temperatures is an efficient practice to prolong postharvest performance of crops with minimal negative impact on produce quality or human health and the environment. However, many fresh produce commodities are susceptible to chilling temperatures, and the application of cold storage is limited as it would cause physiological chilling injury (CI) leading to reduced produce quality. Further, the primary CI becomes a preferred site for pathogens leading to decay and massive produce losses. Thus, chilling sensitive crops should be stored at higher minimal temperatures, which curtails their marketing life and in some cases necessitates the use of other storage strategies. Development of new knowledge about the biological basis for chilling tolerance in fruits and vegetables should allow development of both new varieties more tolerant to cold, and more efficient postharvest storage treatments and storage conditions. In order to improve the agricultural performance of modern crop varieties, including tomato, there is great potential in introgression of marker-defined genomic regions from wild species onto the background of elite breeding lines. To exploit this potential for improving tomato fruit chilling tolerance during postharvest storage, we have used in this research a recombinant inbred line (RIL) population derived from a cross between the red-fruited tomato wild species SolanumpimpinellifoliumL. accession LA2093 and an advanced Solanum lycopersicumL. tomato breeding line NCEBR-1, developed in the laboratory of the US co-PI. The original specific objectives were: 1) Screening of RIL population resulting from the cross NCEBR1 X LA2093 for fruit chilling response during postharvest storage and estimation of its heritability; 2) Perform a transcriptopmic and bioinformatics analysis for the two parental lines following exposure to chilling storage. During the course of the project, we learned that we could measure greater differences in chilling responses among specific RILs compared to that observed between the two parental lines, and thus we decided not to perform transcriptomic analysis and instead invest our efforts more on characterization of the RILs. Performing the transcriptomic analysis for several RILs, which significantly differ in their chilling tolerance/sensitivity, at a later stage could result with more significant insights. The RIL population, (172 lines), was used in field experiment in which fruits were examined for chilling sensitivity by determining CI severity. Following the field experiments, including 4 harvest days and CI measurements, two extreme tails of the response distribution, each consisting of 11 RILs exhibiting either high sensitivity or tolerance to chilling stress, were identified and were further examined for chilling response in greenhouse experiments. Across the RILs, we found significant (P < 0.01) correlation between field and greenhouse grown plants in fruit CI. Two groups of 5 RILs, whose fruits exhibited reproducible chilling tolerant/sensitive phenotypes in both field and greenhouse experiments, were selected for further analyses. Numerous genetic, physiological, biochemical and molecular variations were investigated in response to postharvest chilling stress in the selected RILs. We confirmed the differential response of the parental lines of the RIL population to chilling stress, and examined the extent of variation in the RIL population in response to chilling treatment. We determined parameters which would be useful for further characterization of chilling response in the RIL population. These included chlorophyll fluorescence Fv/Fm, water loss, total non-enzymatic potential of antioxidant activity, ascorbate and proline content, and expression of LeCBF1 gene, known to be associated with cold acclimation. These parameters could be used in continuation studies for the identification and genetic mapping of loci contributing to chilling tolerance in this population, and identifying genetic markers associated with chilling tolerance in tomato. Once genetic markers associated with chilling tolerance are identified, the trait could be transferred to different genetic background via marker-assisted selection (MAS) and breeding. The collaborative research established in this program has resulted in new information and insights in this area of research and the collaboration will be continued to obtain further insights into the genetic, molecular biology and physiology of postharvest chilling tolerance in tomato fruit. The US Co-PI, developed the RIL population that was used for screening and measurement of the relevant chilling stress responses and conducted statistical analyses of the data. Because we were not able to grow the RIL population under field conditions in two successive generations, we could not estimate heritability of response to chilling temperatures. However, we plan to continue the research, grow the RIL progeny in the field again, and determine heritability of chilling tolerance in a near future. The IS and US investigators interacted regularly and plan to continue and expand on this study, since combing the expertise of the Co-PI in genetics and breeding with that of the PI in postharvest physiology and molecular biology will have great impact on this line of research, given the significant findings of this one-year feasibility project.
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Hansen, Peter J., and Zvi Roth. Use of Oocyte and Embryo Survival Factors to Enhance Fertility of Heat-stressed Dairy Cattle. United States Department of Agriculture, 2011. http://dx.doi.org/10.32747/2011.7697105.bard.
Full textAbstract:
The overall goal was to identify survival factors that can improve pregnancy success following insemination or embryo transfer in lactating dairy cows exposed to heat stress. First, we demonstrated that oocytes are actually damaged by elevated temperature in the summer. Then we tested two thermoprotective molecules for their effect on oocyte damage caused by heat shock. One molecule, ceramide was not thermoprptective. Another, insulin-like growth factor-1 (IGF) reduced the effects of heat shock on oocyte apoptosis and oocyte cleavage when added during maturation. We also used lactating cows exposed to heat stress to determine whether bovine somatotropin (bST), which increases IGF1 levels in vivo, would improve fertility in summer. Cows treated with bST received a single injection at 3 days before insemination. Controls received no additional treatment. Treatment with bST did not significantly increase the proportion of inseminated cows diagnosed pregnant although it was numerically greater for the bST group (24.2% vs 17.8%, 124–132 cows per group). There was a tendency (p =0.10) for a smaller percent of control cows to have high plasma progesterone concentrations (≥ 1 ng/ml) at Day 7 after insemination than for bST-treated cows (72.6 vs 81.1%). When only cows that were successfully synchronized were considered, the magnitude of the absolute difference in the percentage of inseminated cows that were diagnosed pregnant between bST and control cows was reduced (24.8 vs 22.4% pregnant for bST and control). Results failed to indicate a beneficial effect of bST treatment on fertility of lactating dairy cows. In another experiment, we found a tendency for addition of IGF1 to embryo culture medium to improve embryonic survival after embryo transfer when the experiment was done during heat stress but not when the experiment was done in the absence of heat stress. Another molecule tested, granulocyte-macrophage colony-stimulating factor (GM-CSF; also called colony-stimulating factor-2), improved embryonic survival in the absence of heat stress. We also examined whether heat shock affects the sperm cell. There was no effect of heat shock on sperm apoptosis (programmed cell death) or on sperm fertilizing ability. Therefore, effects of heat shock on sperm function after ejaculation if minimal. However, there were seasonal changes in sperm characteristics that indicates that some of the decrease in dairy cow fertility during the summer in Israel is due to using semen of inferior quality. Semen was collected from five representative bulls throughout the summer (August and September) and winter (December and January). There were seasonal differences in ion concentration in seminal plasma and in the mRNA for various ion channels known to be involved in acrosome reactions. Furthermore, the proportion of sperm cells with damaged acrosomes was higher in post-thaw semen collected in the summer than in its counterpart collected in winter (54.2 ± 3.5% vs. 51.4 ± 1.9%, respectively; P < 0.08Further examination is required to determine whether such alterations are involved in the low summer fertility of dairy cows.