Evaluation of Contact Heat Transfer Coefficient and Phase Transformation during Hot Stamping of a Hat-Type Part.
Ontology highlight
ABSTRACT:
SUBMITTER: Kim HK
PROVIDER: S-EPMC5507019 | biostudies-other | 2015 Apr
REPOSITORIES: biostudies-other
Similar Datasets
Project description:We study the heat transfer between two nanoparticles held at different temperatures that interact through nonreciprocal forces, by combining molecular dynamics simulations with stochastic thermodynamics. Our simulations reveal that it is possible to construct nano refrigerators that generate a net heat transfer from a cold to a hot reservoir at the expense of power exerted by the nonreciprocal forces. Applying concepts from stochastic thermodynamics to a minimal underdamped Langevin model, we derive exact analytical expressions predictions for the fluctuations of work, heat, and efficiency, which reproduce thermodynamic quantities extracted from the molecular dynamics simulations. The theory only involves a single unknown parameter, namely an effective friction coefficient, which we estimate fitting the results of the molecular dynamics simulation to our theoretical predictions. Using this framework, we also establish design principles which identify the minimal amount of entropy production that is needed to achieve a certain amount of uncertainty in the power fluctuations of our nano refrigerator. Taken together, our results shed light on how the direction and fluctuations of heat flows in natural and artificial nano machines can be accurately quantified and controlled by using nonreciprocal forces.
| S-EPMC10024720 | biostudies-literature
Project description:In order to study the heat transfer of the falling film evaporator with phase change on both sides, in this paper we built the mathematical model and the physical model where the liquid film inside the tube is laminar and turbulent. The film thickness of the condensate at different axial positions, total condensate volume and velocity distribution, and temperature distribution of condensate outside the tube can be obtained by calculating the proposed model. Meanwhile, the liquid film thickness, velocity distribution and temperature distribution inside the tube were obtained by numerical simulation by considering the influence of the liquid film with different compositions on the heat transfer during fluid flow. With ethanol-water as the system, the overall heat transfer coefficient and heat transfer quantity of the falling film evaporator were obtained by the calculation of the model. The accuracy of the proposed model was confirmed by experiments. The model and the calculation of heat transfer proposed in this paper have enormous significance for the basic data and theoretical guidance of the heat transfer performance prediction and operational optimization of the evaporator.
| S-EPMC6549946 | biostudies-literature
Project description: Not available
| S-EPMC11035054 | biostudies-literature
Project description:This study aimed at investigating the performances of air drying of blackberries assisted by airborne ultrasound and contact ultrasound. The drying experiments were conducted in a self-designed dryer coupled with a 20-kHz ultrasound probe. A numerical model for unsteady heat and mass transfer considering temperature dependent diffusivity, shrinkage pattern and input ultrasonic energies were applied to explore the drying mechanism, while the energy consumption and quality were analyzed experimentally. Generally, both airborne ultrasound and contact ultrasound accelerated the drying process, reduced the energy consumption and enhanced the retentions of blackberry anthocyanins and organic acids in comparison to air drying alone. At the same input ultrasound intensity level, blackberries received more ultrasound energies under contact sonication (0.299 W) than airborne sonication (0.245 W), thus avoiding the attenuation of ultrasonic energies by air. The modeling results revealed that contact ultrasound was more capable than airborne ultrasound to intensify the inner moisture diffusion and heat conduction, as well as surface exchange of heat and moisture with air. During air drying, contact ultrasound treatment eliminated the gradients of temperature and moisture inside blackberry easier than airborne ultrasound, leading to more homogenous distributions. Moreover, the total energy consumption under air drying with contact ultrasound assistance was 27.0% lower than that with airborne ultrasound assistance. Besides, blackberries dehydrated by contact ultrasound contained more anthocyanins and organic acids than those dried by airborne ultrasound, implying a higher quality. Overall, direct contact sonication can well benefit blackberry drying in both energy and quality aspects.
| S-EPMC7803686 | biostudies-literature
Project description:Capturing planets in the act of losing their atmospheres provides rare opportunities to probe their evolution history. This analysis has been enabled by observations of the helium triplet at 10,833 angstrom, but past studies have focused on the narrow time window right around the planet's optical transit. We monitored the hot Jupiter HAT-P-32 b using high-resolution spectroscopy from the Hobby-Eberly Telescope covering the planet's full orbit. We detected helium escaping HAT-P-32 b at a 14σ significance,with extended leading and trailing tails spanning a projected length over 53 times the planet's radius. These tails are among the largest known structures associated with an exoplanet. We interpret our observations using three-dimensional hydrodynamic simulations, which predict Roche Lobe overflow with extended tails along the planet's orbital path.
| S-EPMC10246913 | biostudies-literature
Project description:BackgroundExtreme hot weather conditions have been associated with increased morbidity and mortality, but risks are not evenly distributed throughout the population. Previously, a heat vulnerability index (HVI) was created to geographically locate populations with increased vulnerability to heat in metropolitan areas throughout the United States.ObjectivesWe sought to determine whether areas with higher heat vulnerability, as characterized by the HVI, experienced higher rates of morbidity and mortality on abnormally hot days.MethodsWe used Poisson regression to model the interaction of HVI and deviant days (days whose deviation of maximum temperature from the 30-year normal maximum temperature is at or above the 95th percentile) on hospitalization and mortality counts in five states participating in the Environmental Public Health Tracking Network for the years 2000 through 2007.ResultsThe HVI was associated with higher hospitalization and mortality rates in all states on both normal days and deviant days. However, associations were significantly stronger (interaction p-value < 0.05) on deviant days for heat-related illness, acute renal failure, electrolyte imbalance, and nephritis in California, heat-related illness in Washington, all-cause mortality in New Mexico, and respiratory hospitalizations in Massachusetts.ConclusionOur results suggest that the HVI may be a marker of health vulnerability in general, although it may indicate greater vulnerability to heat in some cases.
| S-EPMC3346770 | biostudies-literature
Project description:The determination of the longitudinal spin Seebeck effect (LSSE) coefficient is currently plagued by a large uncertainty due to the poor reproducibility of the experimental conditions used in its measurement. In this work we present a detailed analysis of two different methods used for the determination of the LSSE coefficient. We have performed LSSE experiments in different laboratories, by using different setups and employing both the temperature difference method and the heat flux method. We found that the lack of reproducibility can be mainly attributed to the thermal contact resistance between the sample and the thermal baths which generate the temperature gradient. Due to the variation of the thermal resistance, we found that the scaling of the LSSE voltage to the heat flux through the sample rather than to the temperature difference across the sample greatly reduces the uncertainty. The characteristics of a single YIG/Pt LSSE device obtained with two different setups was (1.143 ± 0.007) 10-7 Vm/W and (1.101 ± 0.015) 10-7 Vm/W with the heat flux method and (2.313 ± 0.017) 10-7 V/K and (4.956 ± 0.005) 10-7 V/K with the temperature difference method. This shows that systematic errors can be considerably reduced with the heat flux method.
| S-EPMC5404258 | biostudies-literature
Project description:Sustained cell proliferation is a fundamental hallmark of cancer, yet its mechanism remains elusive. While tumor cells often cooperate to enhance survival, the specific molecular forces driving this behavior are unknown. We uncover a novel mechanism of tumor growth, that cancer cells proliferate through a contact-dependent transfer of thymidylate (dTMP) via gap junctions with neighboring cells, bypassing canonical biosynthetic and salvage pathways driven by thymidylate synthase (TS) and thymidine kinase (TK1). Importantly, using a genetic mouse model of lung cancer harboring dual TS/TK1 tumor-specific knockout, we show that cancer cells lacking canonical synthesis maintain proliferation. These findings advance the current dogma of a ubiquitous nucleotide-driven activation in cancer, suggesting that a programmed dTMP re-equilibration sustains tumor growth. This novel mechanism could be exploited in cancer therapy.
2024-08-05 | GSE271721 | GEO
Project description:Light absorption in conducting materials produces heating of their conduction electrons, followed by relaxation into phonons within picoseconds, and subsequent diffusion into the surrounding media over longer timescales. This conventional picture of optical heating is supplemented by radiative cooling, which typically takes place at an even lower pace, only becoming relevant for structures held in vacuum or under extreme thermal isolation. Here, we reveal an ultrafast radiative cooling regime between neighboring plasmon-supporting graphene nanostructures in which noncontact heat transfer becomes a dominant channel. We predict that more than 50% of the electronic heat energy deposited on a graphene disk can be transferred to a neighboring nanoisland within a femtosecond timescale. This phenomenon is facilitated by the combination of low electronic heat capacity and large plasmonic field concentration in doped graphene. Similar effects should occur in other van der Waals materials, thus opening an unexplored avenue toward efficient heat management.Electron relaxation, which is the dominant release channel of electronic heat in nanostructures, occurs with characteristic times of several picoseconds. Here, the authors predict that an ultrafast (femtosecond) radiative cooling regime takes place in plasmonically active neighboring graphene nanodisks prior to electron relaxation.
| S-EPMC5431947 | biostudies-literature
Project description:Hot flashes are a significant source of symptom burden that negatively impacts quality of life (QOL). For women who have contraindications to, or are unwilling to consider, estrogens or antidepressants for bothersome hot flashes, there are limited effective pharmacologic or complementary and alternative medicines.This single-arm phase II trial studied the efficacy of S-adenosyl-L-methionine (SAMe) for the treatment of hot flashes. Eligible women were required to have reported ?14 hot flashes per week for ?1 month. The patients were treated with SAMe at a dose of 400 mg twice daily to evaluate whether a reduction in hot flash score appeared to be better than the historical placebo response of approximately 25%. The women kept a daily hot flash diary during a baseline week and then daily during weeks 2-7. The primary endpoint was the change from baseline to week 7 in hot flash score and hot flash frequency. Secondary endpoints included toxicity analyses and the effect of SAMe on QOL.From October 28, 2010 to January 30, 2012, 43 women were treated with SAMe. The decrease in mean percent of baseline hot flash score and frequency was 35.4 and 32.6%, respectively. When compared to the historical placebo response of 25%, the effect of SAMe on hot flash score was not statistically significant (p?=?0.09). Treatment was well tolerated with expected grade 1/2 gastrointestinal toxicity and no negative effect on QOL.The use of SAMe does not appear to significantly reduce hot flashes more than would be expected with a placebo.
| S-EPMC4973573 | biostudies-literature