Academic literature on the topic 'Maximum temperature (Tmax)'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the lists of relevant articles, books, theses, conference reports, and other scholarly sources on the topic 'Maximum temperature (Tmax).'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Journal articles on the topic "Maximum temperature (Tmax)"
1
Al-Jiboori, Monim, Mahmoud Jawad Abu Al-Shaeer, and Ahemd S. Hassan. "Statistical Forecast of Daily Maximum Air Temperature in Arid Areas at Summertime." Journal of Mathematical and Fundamental Sciences 52, no. 3 (2020): 353–65. http://dx.doi.org/10.5614/j.math.fund.sci.2020.52.3.8.
Full textAbstract:
Based on historical observations of summers for the period from 2004 to 2018 with a focus on daily maximum and minimum air temperatures and wind speed recorded at 0600 GMT, a non-linear regression hypothesis is developed for forecasting daily maximum air temperature (Tmax) in arid areas such as Baghdad International airport station, which has a hot climate with no cloud cover or rain. Observations with dust storm events were excluded, thus this hypothesis could be used to predict daily Tmax on any day during summers characterized by fair weather. Using mean annual daily temperature range, daily minimum temperature, and the trend of maximum temperature with wind speed, Tmax was forecasted and then compared to those recorded by meteorological instruments. To improve the accuracy of the hypothesis, daily forecast errors, bias, and mean absolute error were analyzed to detect their characteristics through calculating relative frequencies of occurrence. At the end of this analysis, a value of (-0.45ºC) was added to the hypothesis as a bias term.
2
Sachindra, D. A., F. Huang, A. F. Barton, and B. J. C. Perera. "Statistical downscaling of general circulation model outputs to evaporation, minimum temperature and maximum temperature using a key-predictand and key-station approach." Journal of Water and Climate Change 6, no. 2 (2014): 241–62. http://dx.doi.org/10.2166/wcc.2014.145.
Full textAbstract:
A key-predictand and key-station approach was employed in downscaling general circulation model outputs to monthly evaporation, minimum temperature (Tmin) and maximum temperature (Tmax) at five observation stations concurrently. Tmax was highly correlated (magnitudes above 0.80 at p ≤ 0.05) with evaporation and Tmin at each individual station, hence Tmax was identified as the key predictand. One station was selected as the key station, as Tmax at that station showed high correlations with evaporation, Tmin and Tmax at all stations. Linear regression relationships were developed between the key predictand at the key station and evaporation, Tmin and Tmax at all stations using observations. A downscaling model was developed at the key station for Tmax. Then, outputs of this downscaling model at the key station were introduced to the linear regression relationships to produce projections of monthly evaporation, Tmin and Tmax at all stations. This key-predictand and key-station approach was proved to be effective as the statistics of the predictands simulated by this approach were in close agreement with those of observations. This simple multi-station multivariate downscaling approach enabled the preservation of the cross-correlation structures of each individual predictand among the stations and also the cross-correlation structures between different predictands at individual stations.
3
Liu, Binhui, Ming Xu, Mark Henderson, Ye Qi, and Yiqing Li. "Taking China's Temperature: Daily Range, Warming Trends, and Regional Variations, 1955–2000." Journal of Climate 17, no. 22 (2004): 4453–62. http://dx.doi.org/10.1175/3230.1.
Full textAbstract:
Abstract In analyzing daily climate data from 305 weather stations in China for the period from 1955 to 2000, the authors found that surface air temperatures are increasing with an accelerating trend after 1990. They also found that the daily maximum (Tmax) and minimum (Tmin) air temperature increased at a rate of 1.27° and 3.23°C (100 yr)−1 between 1955 and 2000. Both temperature trends were faster than those reported for the Northern Hemisphere, where Tmax and Tmin increased by 0.87° and 1.84°C (100 yr)−1 between 1950 and 1993. The daily temperature range (DTR) decreased rapidly by −2.5°C (100 yr)−1 from 1960 to 1990; during that time, minimum temperature increased while maximum temperature decreased slightly. Since 1990, the decline in DTR has halted because Tmax and Tmin increased at a similar pace during the 1990s. Increased minimum and maximum temperatures were most pronounced in northeast China and were lowest in the southwest. Cloud cover and precipitation correlated poorly with the decreasing temperature range. It is argued that a decline in solar irradiance better explains the decreasing range of daily temperatures through its influence on maximum temperature. With declining solar irradiance even on clear days, and with decreases in cloud cover, it is posited that atmospheric aerosols may be contributing to the changing solar irradiance and trends of daily temperatures observed in China.
4
Alfaro, Eric J., Alexander Gershunov, and Daniel Cayan. "Prediction of Summer Maximum and Minimum Temperature over the Central and Western United States: The Roles of Soil Moisture and Sea Surface Temperature." Journal of Climate 19, no. 8 (2006): 1407–21. http://dx.doi.org/10.1175/jcli3665.1.
Full textAbstract:
Abstract A statistical model based on canonical correlation analysis (CCA) was used to explore climatic associations and predictability of June–August (JJA) maximum and minimum surface air temperatures (Tmax and Tmin) as well as the frequency of Tmax daily extremes (Tmax90) in the central and western United States (west of 90°W). Explanatory variables are monthly and seasonal Pacific Ocean SST (PSST) and the Climate Division Palmer Drought Severity Index (PDSI) during 1950–2001. Although there is a positive correlation between Tmax and Tmin, the two variables exhibit somewhat different patterns and dynamics. Both exhibit their lowest levels of variability in summer, but that of Tmax is greater than Tmin. The predictability of Tmax is mainly associated with local effects related to previous soil moisture conditions at short range (one month to one season), with PSST providing a secondary influence. Predictability of Tmin is more strongly influenced by large-scale (PSST) patterns, with PDSI acting as a short-range predictive influence. For both predictand variables (Tmax and Tmin), the PDSI influence falls off markedly at time leads beyond a few months, but a PSST influence remains for at least two seasons. The maximum predictive skill for JJA Tmin, Tmax, and Tmax90 is from May PSST and PDSI. Importantly, skills evaluated for various seasons and time leads undergo a seasonal cycle that has maximum levels in summer. At the seasonal time frame, summer Tmax prediction skills are greatest in the Midwest, northern and central California, Arizona, and Utah. Similar results were found for Tmax90. In contrast, Tmin skill is spread over most of the western region, except for clusters of low skill in the northern Midwest and southern Montana, Idaho, and northern Arizona.
5
Milošević, Dragan D., Stevan M. Savić, Uglješa Stankov, et al. "Maximum temperatures over Slovenia and their relationship with atmospheric circulation patterns." Geografie 122, no. 1 (2017): 1–20. http://dx.doi.org/10.37040/geografie2017122010001.
Full textAbstract:
This paper examines temporal and spatial patterns of annual and seasonal maximum temperatures (Tmax) in Slovenia and their relationship with atmospheric circulation patterns. A significant increase in maximum temperature (Tmax; from 0.3°C to 0.5°C·decade-1) was observed throughout the country at the annual scale in the period 1963–2014. Significant positive trends are observed on all stations in summer (from 0.4°C to 0.7°C·decade-1) and spring (from 0.4°C to 0.6°C·decade-1). The results indicate significant correlations between the mean annual maximum temperature (Tmax) and the East Atlantic Oscillation (EA) (from 0.5 to 0.7), the Arctic Oscillation (AO) (from 0.4 to 0.7) and the Scandinavian Oscillation (SCAND) (from −0.3 to −0.4) throughout the country. A significant EA influence is observed in all seasons, while the AO influence is noticed in winter and spring, SCAND in spring and summer, the North Atlantic Oscillation (NAO) and the Mediterranean Oscillation (MO) in winter, the East Atlantic/Western Russia Oscillation (EA/WR) in summer and the El Nino Southern Oscillation (ENSO) in autumn.
6
Penalba, Olga Clorinda, María Laura Bettolli, and Pablo Andrés Krieger. "Surface Circulation Types and Daily Maximum and Minimum Temperatures in Southern La Plata Basin." Journal of Applied Meteorology and Climatology 52, no. 11 (2013): 2450–59. http://dx.doi.org/10.1175/jamc-d-13-039.1.
Full textAbstract:
AbstractLa Plata basin is one of the most important agricultural and hydropower-producing regions in the world. Extreme climate events such as cold and heat waves and frost events have a significant socioeconomic impact. This work analyzes the influence of the surface circulation in southern South America on daily maximum temperature TMAX and daily minimum temperature TMIN in southern La Plata basin. A Z test for the comparison of mean values and a Kolmogorov–Smirnov test for the comparison of distributions of TMAX and TMIN associated with each circulation pattern were performed. Specific daily surface circulation types are found to contribute to TMAX and TMIN anomalies and to have a predominant occurrence in the development of the extreme temperature events in the region. The TMAX spatial response to the regional low-level circulation is more homogenous and extended than is the response of TMIN.
7
Muter, Sara A., Jasim H. Kadhum, and Ahmed S. Hassan. "Approaching of May maximum surface air temperature to characteristic summer season for Baghdad city." Scientific Review Engineering and Environmental Studies (SREES) 30, no. 3 (2021): 400–410. http://dx.doi.org/10.22630/pniks.2021.30.3.34.
Full textAbstract:
Seasonal variability is the complex non-linear response of the physical climate system. There are two types of natural variability: those external and internal to the climate system. In any given season, natural variability may cause the climate to be different than its long-term average. This study examines with the seasonal variation of the maximum temperatures during the summer season. In addition, the maximum temperatures in May become close to the characteristics of the summer season. The monthly data for maximum temperature of May, June and July were used from Iraqi Meteorological Organization and Seismology (IMOS) for 47 years from 1970 to 2017 for Baghdad city. This period was long enough to estimate the range of approaching maximum temperature (Tmax) May to summer. Results revealed a significant Tmax for Baghdad during the second period (1992–2017) and ?shown similar behavior of Tmax in May to June and July; on the contrary that first period (1970–1991). In second period, two phases have been found out, positive phase and negative phase. The positive phase were happened in 1995, 1999, and 2006, and the negative phase was four cases (1992, 2004, 2013, and 2016), while a few cases recorded in first period. The amplitudes of monthly variability had same distance of leaner correlation especially in 1999 and 2013 that represent coherent wave with summer seasons. The variance difference for Tmax between May and June approximately was 2°C for second study’s period, while exceed this range in first period. This variance change to 7.5°C when found difference between July and May.
8
Yuan, Zhe, Jun Yin, Mengru Wei, and Yong Yuan. "Spatio-Temporal Variations in the Temperature and Precipitation Extremes in Yangtze River Basin, China during 1961–2020." Atmosphere 12, no. 11 (2021): 1423. http://dx.doi.org/10.3390/atmos12111423.
Full textAbstract:
Based on daily maximum temperature (Tmax), minimum temperature (Tmin), and precipitation of the Yangtze River Basin (YRB) from 1961 to 2020, we employed the trend analysis method and correlation analysis method to analyze spatiotemporal variations in 10 extreme indices and their associations with atmospheric and oceanic circulations. Results indicated that maximum Tmax (TXx), maximum Tmin (TNx), and minimum Tmin (TNn) all increased significantly, at rates of 0.19 °C, 0.19 °C, and 0.37 °C per decade, respectively, whereas minimum Tmax (TXn) did not show any significant trend. The diurnal temperature range (DTR) decreased by 0.09 °C per decade as minimum temperatures increased faster than maximum temperatures. TNx and TNn increased significantly in the majority of the YRB, but TXn showed no significant increases. TXn increased significantly in the upper reaches of the Yangtze River. The DTR increased significantly in the Jinsha River Basin and the lower reaches of the Yangtze River. Rx1day (maximum 1-day precipitation), SDII (Simple daily intensity index) and R99p (extremely wet-day precipitation) increased significantly, at rates of 1.12 mm, 0.09 mm, and 5.87 mm per decade, respectively, but the trends of Rx5day (maximum 5-day precipitation) and PRCPTOT (total wet-day precipitation) were not significant. However, the trends of precipitation extreme indices were not statistically significant in most of the YRB. In the future, maximum temperature and minimum temperature might increase while DTR might decrease. But, the trends of precipitation extremes in the future were ambiguous. Nearly all the extreme indices were related to the variability of Atlantic multidecadal oscillation (AMO) in the YRB. In addition, the correlations between extreme temperature indices and AMO are higher than that of extreme precipitation indices.
9
CARVALHO, PATRÍCIA GONÇALVES BAPTISTA DE, FABIAN BORGHETTI, MARCOS SILVEIRA BUCKERIDGE, LAURO MORHY, and EDIVALDO XIMENES FERREIRA FILHO. "Temperature-dependent germination and endo-beta -mannanase activity in sesame seeds." Revista Brasileira de Fisiologia Vegetal 13, no. 2 (2001): 139–48. http://dx.doi.org/10.1590/s0103-31312001000200003.
Full textAbstract:
The effects of temperature on germination and endo-beta-mannanase activity in seeds of Sesamum indicum was investigated. The minimum germination temperature (Tmin) lies between 12.8°C and 13.2°C while the maximum temperature (Tmax) is located between 45.5°C and 46°C. Germinabilities are statistically not different from estimated viability (88%) between 18.8°C and 43.2°C. The Mann-Whitney test indicated the interval 31.9°C to 35.1°C as the optimum temperature (Topt) range for germination rate. When seeds incubated at temperatures at or below the Tmin and close to or above the Tmax were transferred to 30°C, those incubated at lower temperatures achieved high germinability. On the other hand, the higher the pre-incubation temperature above Tmax, the lower the germinability achieved near Topt. Seed endosperm cell wall was found to contain mannose as the main monosaccharide. An increase in endo-beta-mannanase activity in the micropylar endosperm prior to seed germination was observed only at supra-optimum temperature.
10
Corobov, Roman, Scott Sheridan, Kristie Ebi, and Nicolae Opopol. "Warm Season Temperature-Mortality Relationships in Chisinau (Moldova)." International Journal of Atmospheric Sciences 2013 (February 19, 2013): 1–9. http://dx.doi.org/10.1155/2013/346024.
Full textAbstract:
Results of the epidemiological study of relationships between air temperature and daily mortality in Chisinau (Moldova) are presented. The research’s main task included description of mortality dependence on different temperature variables and identification of thermal optimum (minimal mortality temperature, MMT). Total daily deaths were used to characterize the mortality of urban and rural populations in April–September of 2000–2008, excluding the extremely warm season of 2007. The simple moving average procedure and 2nd-order polynomials were used for daily mean (Tmean), maximum (Tmax), and minimum (Tmin) temperatures and mortality approximation. Thermal optimum for mortality in Chisinau (15.2 deaths) was observed at Tmean, Tmax, and Tmin about 22°C, 27-28°C, and 17-18°C, respectively. Considering these values as certain cut-points, the correlations between temperature and mortality were estimated below and above MMTs. With air temperatures below its optimal value, each additional 1°C increase of Tmean (Tmax, Tmin) was accompanied by 1.40% (1.35%, 1.52%) decrease in daily mortality. The increase of Tmean and Tmax above optimal values was associated with ~2.8% and 3.5% increase of mortality; results for Tmin were not statistically significant. The dependency of mortality on apparent temperature was somewhat weaker below MMT; a significant relationship above MMT was not identified.
Book chapters on the topic "Maximum temperature (Tmax)"
1
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.
Full textAbstract:
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.
Conference papers on the topic "Maximum temperature (Tmax)"
1
Hu, Qingxiang, Wei Peng, Gang Zhao, and Jie Wang. "Study on Water Cooler Performance for High Temperature Helium Experimental System." In 2021 28th International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/icone28-65596.
Full textAbstract:
Abstract Very-high-temperature gas-cooled reactor (VHTR) has good inherent safety and is one of the six reactor technologies of Generation IV nuclear energy systems. The ultra-high core outlet temperature makes VHTR suitable for process heat applications such as hydrogen production. The intermediate heat exchanger (IHX) is the key equipment for energy transfer between VHTR and the process heat application system. To verify the high temperature performance of IHX, it is generally necessary to set up a high temperature helium test system to conduct a series of performance tests. In this experimental system, a well-behaved water cooler needs to be designed to cool down the high-temperature helium in the experimental loop to ensure the safety of the experimental system. In the present study, the effect of the cooling water flow rate G, the cooling water injection position L, and the lower heat exchange tubes material were analyzed. The results show that increasing the flow rate of the cooling water, the maximum temperature of the tube sheet Tmax decreases and the temperature gradient in the flow direction ∇Ty increases. Tmax increases first and then decreases with the increasing L. There exists an optimal cooling water injection position between L = 175mm and 225mm. The variation of ∇Ty is the opposite. The use of ceramic instead of steel reduces Tmax by about 295K and reduces ∇Ty by half. Subsequent research and optimization on structure parameters of the water cooler are expected to further improve the cooling performance.
2
Liu, Yuliang, Jia Lou, David B. Bogy, and Guangyu Zhang. "A Thermo-Mechanical Finite Element Analysis of Light Sliding Contact at the Head-Disk Interface." In ASME/STLE 2012 International Joint Tribology Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/ijtc2012-61063.
Full textAbstract:
A three dimensional finite element model of a rigid sphere lightly sliding over an elastic-perfectly plastic multilayered medium under thermo-mechanical surface loading is developed in order to investigate the mechanical and thermal responses during the light sliding contact of a spherical corner or thermal protrusion of a slider with a rotating disk. In this simulation, the effects of the magnetic recording layer thickness t and sliding contact parameters such as normal load F and friction coefficient μ on maximum temperature Tmax of head-disk interface (HDI) and maximum scratch depth h on the multilayered disk media are analyzed for both glass and aluminum disks. The results show that the magnetic recording layer thickness t has a negligible effect on the maximum temperature Tmax of the HDI and scratch depth h on the disk for both types of substrates, but the sliding contact parameters strongly affect the temperature variation and mechanical deformation of the HDI. In addition, the effect of the disk material is also very pronounced.
3
Suszko, Arthur, and Mohamed S. El-Genk. "A Composite Cu/HOPG Heat Spreader for Immersion Cooling of High Power Chips." In ASME 2015 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems collocated with the ASME 2015 13th International Conference on Nanochannels, Microchannels, and Minichannels. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/ipack2015-48678.
Full textAbstract:
Presented are the results of a 3-D numerical analysis of a composite heat spreader for immersion cooling of a 20 × 20 mm microprocessor. The spreader is comprised of two 0.5 mm thick Copper (Cu) laments separated by a layer of highly ordered pyrolytic graphite (HOPG), 0.25–1.0 mm thick. The exposed surface of the top Cu lament has an average roughness, Ra = 1.79 μm and is cooled by saturation nucleate pool boiling of PF-5060 dielectric liquid. Investigate is the impact of δHOPG on the total power removed, the maximum temperature of the underlying chip, Tmax, and mitigating the chip hot spots. Increasing δHOPG increases the total power removed, but also increases Tmax. The spreader with a 1.0 mm-thick δHOPG is capable of removing 318 W, without exceeding 90% of the critical heat flux (CHF), at Tmax = 120°C. This power removal is significantly higher than that with an all Cu spreader of the same thickness of 90 W, but at much lower Tmax of 67°C. Composite spreaders with δHOPG = 0.25, 0.5, and 0.75 mm are capable of removing up to 160 W at Tmax = 85°C, 228 W at 100°C, and 292W at 115°C, respectively. The HOPG suppresses the transmission of hot spots to the spreader surface and increasing δHOPG does not mitigate the hot spots.
4
Buchhorn, Nico, Sebastian Kukla, and Beate Bender. "Increased Load Carrying Capacity of Large Tilting-Pad Journal Bearings by Injection of Cold Oil." In ASME Turbo Expo 2016: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/gt2016-57475.
Full textAbstract:
In this paper a theoretical study with the aim to achieve higher load capacity of large tilting-pad turbine bearings is presented. The main focus is set on the reduction of thermal gradients inside the pad and thus, of adverse thermomechanical deformations. This allows for the increase of either the load carrying capacity, minimum film thickness hmin, and/or decrease maximum pad temperature Tmax. Subject of the investigation is a 5-pad tilting-pad bearing with rocker pivots. Each pad arc measures 56° and the pivot is positioned at 60 %. By having a 500mm inner diameter the 350mm long bearing features a relative clearance of 1.28% and nominal preload of 0.23. It is shown that the axial pad bending Δh (crowning) has a major impact on film thickness and pressure distributions and thus on the operational safety parameters. In order to reduce this effect, radial bores through the pad supplying pressurized cold oil (Tinj = 50 °C) are simulated. Despite the evident increase in oil film pressure, the primary purpose of the injection is to rinse away the layer of hot oil sticking to the pad surface. The maximum pad temperature and the overall pad temperature gradients are thereby decreased. The code used for simulation solves Reynolds and energy equations and computes thermomechanical deformations simultaneously. However, the simulations are carried out for one single pad only and are therefore supported by boundary conditions taken from experiments. In order to determine the impact of the approach on the static bearing characteristics, diameter and location of the bores are varied (0.3mm ≤ db ≤ 0.5mm). It is shown that pad crowing can be reduced significantly: The axial deviation of the film thickness Δh can be decreased from Δh = 47 μm to Δh = 31 μm, while the maximum temperature Tmax can be decreased by 20 K. Further, the minimum film thickness hmin can be increased by 16 μm. Subsequently, allowing the same limits for hmin and Tmax for the new design, the load capacity can be raised by up to 1.21MPa ≙ 44 %.
5
Al-Sood, Maher M. Abou, Mahmoud A. Ahmed, and Yousef M. Abdel-Rahim. "Optimum Compression Ratio Variation of 4-Stroke, Direct Injection Diesel Engine for Optimum Performance." In ASME 2011 International Mechanical Engineering Congress and Exposition. ASMEDC, 2011. http://dx.doi.org/10.1115/imece2011-62156.
Full textAbstract:
A thermodynamic model for simulation the performance of a four-stroke direct-injection (DI) diesel engine is developed. The simulation model includes detailed sub-models for fuel burning rate, combustion products, thermodynamic properties of working fluid, heat transfer, fluid flow, and both soot and NOx formation mechanisms. To validate the model, comparisons between experimental and predicted results for different engines, operating under different conditions were conducted. Comparisons show that there is a good concurrence between measured and predicted values. An optimization analysis is conducted for seeking an optimum variation of compression ratio to achieve pre-set objective target of constant minimum brake specific fuel consumption (bsfc). The optimization analysis is performed under the constrain that the maximum pressure and temperature inside the cylinder not exceed the maximum allowable pressure and temperature of the conventional engine (constant rc). Varying compression ratio is optimized with the previous condition. Results indicated that, at the values of rc ranged between 16.4 and 17.8, the optimum bsfc is attained with an increase in brake power by about 3.8%, while the bsfc and soot emission are reduced by about 4.4% and 21%, respectively. In addition to an increase in NOx, maximum pressure (pmax), and maximum temperature (Tmax) by about 75%, 6% and 4.3%, respectively.
6
Wittig, S., A. Glahn, and J. Himmelsbach. "Influence of High Rotational Speeds on Heat Transfer and Oil Film Thickness in Aero Engine Bearing Chambers." In ASME 1993 International Gas Turbine and Aeroengine Congress and Exposition. American Society of Mechanical Engineers, 1993. http://dx.doi.org/10.1115/93-gt-209.
Full textAbstract:
Increasing the thermal loading of bearing chambers in modern aero engines requires advanced techniques for the determination of heat transfer characteristics. In the present study, film thickness and heat transfer measurements have been carried out for the complex two–phase oil/air flow in bearing chambers. In order to ensure real engine conditions, a new test facility has been built up, designed for rotational speeds up to n = 16000 rpm and maximum flow temperatures of Tmax = 473K. Sealing air and lubrication oil flow can be varied nearly in the whole range of aero engine applications. Special interest is directed towards the development of an ultrasonic oil film thickness measuring technique which can be used without any reaction on the flow inside the chamber. The determination of local heat transfer at the bearing chamber housing is based on a well known temperature gradient method using surface temperature measurements and a finite element code to determine temperature distributions within the bearing chamber housing. The influence of high rotational speed on the local heat transfer and the oil film thickness is discussed.
7
Travkin, V. S. "Relating Semiconductor Heat Sink Local and Non-Local Experimental and Simulation Data to Upper Scale Design Goals." In ASME 2001 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2001. http://dx.doi.org/10.1115/imece2001/htd-24383.
Full textAbstract:
Abstract The primary difficulty in semiconductor heat sink (and many other types of heat exchangers) research and design is not a lack of interest or money, but rather confusion with what being looked for and adequacy of the tools used for the search. As recently shown, there are few meaningful parameters (apart from sizes and weight) or physical characteristics of interest in semiconductor cooler design are local values. Even the maximum temperature of the base Tmax or semiconductor temperature are not local. In this work outlined the description in detail of arguments on how, and for what reasons, the measured data are to be simulated or measured and represented in a way that allows design goals to be formulated primarily with bulk physical characteristics. We demonstrate why studies of only averaged local integrated variables are not enough. Four sample semiconductor heat sinks of two morphologies (three samples of round pin fin and one sample of longitudinal rib fin sinks) were studied by different techniques and models. There were changes in by-pass values, external heat flux and flow rate. The results are depicted with using new parameters that better represent the needs of a design process as well as the usual parameters used in the past. Characteristics reported are the heat transfer rate in solid phase, relative fin effectiveness, and influence of only morphology features among others. Some suggestions for heat sink design are discussed.
8
Sun, Jun, and Zhixin Li. "Molecular Dynamics Study on the Effect of Adsorbed Layer on Accommodation Coefficients in Micro Gas Flow." In ASME 2008 6th International Conference on Nanochannels, Microchannels, and Minichannels. ASMEDC, 2008. http://dx.doi.org/10.1115/icnmm2008-62088.
Full textAbstract:
Tangential momentum accommodation coefficient (TMAC) is reported to be less than unity in rarefied gas flow and greatly influenced by many factors such as temperature and adsorbed layers. According to the definition, a proper statistical algorithm in NEMD method is described and verified. Adsorbed layers occur on walls due to strong gas-wall interactions and the effect on TMAC are studied in two dimensional isothermal Poiseuille flow in smooth micro-channels under the conditions of various temperatures, driving forces, and Kn. The simulation results indicate that when gas-wall interactions become stronger, TMAC increases to maximum firstly and decreases a little. Besides, the effects of temperature and Kn on TMAC are not monotonous with the existence of adsorbed layer. In addition, normal momentum accommodation coefficient (NMAC) is almost unity for isothermal flow in smooth microchannels.
9
Tang, Wei, Maxim Gussev, Zhili Feng, et al. "Friction Stir Welding and Preliminary Characterization of Irradiated 304 Stainless Steel." In ASME 2019 Pressure Vessels & Piping Conference. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/pvp2019-93899.
Full textAbstract:
Abstract The mitigation of helium induced cracking in the heat affected zone (HAZ), a transition metallurgical zone between the weld zone and base metal, during repair welding is a great challenge in nuclear industry. Successful traditional fusion welding repairs are limited to metals with a maximum of a couple of atomic parts per million (appm) helium, and structural materials helium levels in operating nuclear power plants are generally exceed a couple of appm after years of operations. Therefore, fusion welding is very limited in nuclear power plants structural materials repairing. Friction stir welding (FSW) is a solid-state joining technology that reduces the drivers (temperature and tensile residual stress) for helium-induced cracking. This paper will detail initial procedural development of FSW weld trials on irradiated 304L stainless steel (304L SS) coupons utilizing a unique welding facility located at one of Oak Ridge National Laboratory’s hot cell facilities. The successful early results of FSW of an irradiated 304L SS coupon containing high helium are discussed. Helium induced cracking was not observed by scanning electron microscopy in the friction stir weld zone and the metallurgical zones between the weld zone and base metal, i.e. thermal mechanical affected zone (TMAZ) and HAZ. Characterization of the weld, TMAZ and HAZ regions are detailed in this paper.
10
Hossain, Mohammad K., Md Mahmudur R. Chowdhury, Mahesh Hosur, and Nydeia W. Bolden. "Viscoelastic Properties of Carbon/Epoxy Amino-Functionalized Graphene Nanoplatelet Composite." In ASME 2016 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/imece2016-67856.
Full textAbstract:
A systematic study was conducted on processing and characterizing of the carbon fiber reinforced epoxy polymer (CFRP) composite to enhance its viscoelastic and thermal properties through the integration of an optimized amount of amino-functionalized graphene nanoplatelet (NH2-GNP). Epoxy resin, EPON 828, was modified through the integration of 0.1–0.5 wt% of NH2-GNP as a reinforcing agent. The GNP was infused into the resin using a high intensity ultrasonic processor followed by a three roll milling for better dispersion. Epikure 3223 curing agent was then added to the modified resin and mixed using a high-speed mechanical stirrer. The nanophased epoxy was then used to fabricate CFRP nanocomposites using the compression molding process. Dynamic mechanical analysis (DMA) and thermomechanical analysis (TMA) were performed to analyze viscoelastic and thermal performances of these composites. In all cases, 0.4 wt% GNP-infused epoxy nanocomposite exhibited the best properties. The 0.4 wt% GNP modified carbon fiber/epoxy composites showed 19% and 23% improvement in storage modulus and loss modulus, respectively. Glass transition temperature (Tg) was improved by 16% maximum at 0.4 wt% GNP loading due to better interfacial interaction and effective load transfer between NH2-GNP and epoxy resin. Moreover, there were about 13% and 28% reduction in the coefficient of thermal expansion (CTE) before and after Tg, respectively.