Prediction Of Temperature Increase Research Articles

Sublethal doses of insecticide reduce thermal tolerance of a stingless bee and are not avoided in a resource choice test.

Insecticides and climate change are among the multiple stressors that bees face, but little is known about their synergistic effects, especially for non-Apis bee species. In laboratory experiments, we tested whether the stingless bee Tetragonula hockingsi avoids insecticide in sucrose solutions and how T. hockingsi responds to insecticide and heat stress combined. We found that T. hockingsi neither preferred nor avoided sucrose solutions with either low (2.5 × 10-4 ng µl-1 imidacloprid or 1.0 × 10-4 ng µl-1 fipronil) or high (2.5 × 10-3 ng µl-1 imidacloprid or 1.0 × 10-3 ng µl-1 fipronil) insecticide concentrations when offered alongside sucrose without insecticide. In our combined stress experiment, the smallest dose of imidacloprid (7.5 × 10-4 ng) did not significantly affect thermal tolerance (CTmax). However, CTmax significantly reduced by 0.8°C (±0.16 SE) and by 0.5°C (±0.16 SE) when bees were fed as little as 7.5 × 10-3 ng of imidacloprid or 3.0 × 10-4 ng of fipronil, respectively, and as much as 1.5°C (±0.16 SE) and 1.2°C (±0.16 SE) when bees were fed 7.5 × 10-2 ng of imidacloprid or 3.0 × 10-2 ng of fipronil, respectively. Predictions of temperature increase, and increased insecticide use in the tropics suggest that T. hockingsi will be at increased risk of the effects of both stressors in the future.

Standard versus natural fire resistance for partially restrained composite floor beams: 2-Analysis

A thermo-structural reduced-order finite element modeling approach is used to evaluate the results of two fire tests (presented in Part 1 of this study) on identically designed, highly composite floor beam specimens with SFRM protection, shear tab connections at each end, a lightweight concrete slab on a corrugated metal deck, and partial restraint of both axial thermal expansion and connection rotation. Model validation is performed for both an ASTM E119 standard fire and a parametric natural fire, with a constant load applied to the specimens via four-point bending to a maximum service condition. Predictions of temperature increase in the protected steel beam and the composite slab show good agreement with experimental measurements by implementing a series of weighted averaging strategies on thermal FE results for 2D cross-sections at the thick and thin portions of the composite slab. Predictions of temperature-induced deflections, which used the results of thermal FE analysis as input, also show good agreement with experimental results when little-to-no rotational stiffness is applied to the connections. The numerical models are then re-analyzed at a reduced loading level (representing a middling service condition) and with varying rotational stiffness in the shear tab connections. The results of parametric analysis are used to draw correlations between standard fire resistance and natural fire robustness as a function of applied loading and temperature increase in the steel beam. Simplified modeling strategies and recommendations for performance-based structural-fire design are discussed, and opportunities for future research are highlighted.

고무차륜 강체전차선에 해빙 루프 전류 인가 시 온도상승 예측 연구

고무차륜 강체전차선에 해빙 루프 전류 인가 시 온도상승 예측 연구

Measurement and Prediction of Temperature Increase during Isothermal Forging of Titanium–6 Aluminum–4 Vanadium

Abstract Titanium–6 aluminum–4 vanadium is isothermally forged at 1,023–1,223 K (750°C–950°C) at 0.05, 0.1, and 1.0/s using a 1,500-ton forging press simulator. The temperature increase of a workpiece (100 mm in diameter, 50 mm in height) during forging is measured by inserting thermocouples into the workpiece, and this increase is predicted using finite element analysis (FEA). The physical properties necessary for the FEA are determined using the same material as the forged one in order to improve the prediction accuracy. The true stress–true strain curves and heat transfer coefficient between the workpiece and dies are inversely obtained. The temperature change predicted by FEA using those parameters and curves agreed well with the experimental results. In the FEA, the inelastic heat fraction, which is a conversion factor for plastic deformation energy to heat energy, did not depend on the strain rate, but it remained the same at strain rates of 0.05–1.0/s. This result suggests that the large heat capacity of the workpiece in this study suppressed the effect of heat transfer between the workpiece and dies/air on the temperature of the workpiece. It is also shown that the prediction accuracy of the workpiece’s temperature could be degraded unless the appropriate specific heat value is used, especially near the β transus temperature, which can be affected by the composition of light elements.

Impact-initiated behavior and reaction mechanism of W/Zr composites with SHPB setup

The dynamic compressive behavior of a hot pressed tungsten/zirconium (W/Zr) composite with a mass proportion of 34:64 (W:Zr) was experimentally investigated using a split Hopkinson pressure bar and a high-speed camera. The W/Zr composite has high strength but some brittle characteristics; when subjected to a strong enough impact loading, the sample is crushed, rapidly releasing high amounts of energy as a result. This impact-initiated reaction depends on the loading conditions, where a higher loading strain rate resulting a smaller fragment size. The Zr phase is involved in the reaction as the active component of the composite, and these fragments can be divided into small, medium, and large fragments with their reactions labeled as “fire ball,” “spark,” and “no react” respectively. A simple model is constructed to analyze the heat generated during plastic deformation based on yield stress, crack speed and the thermal properties of the brittle material. Our proposed model’s prediction of temperature increase at initiation may reach several hundred degrees Celsius.

An assessment of observed and projected temperature changes in Armenia

Future changes in annual and seasonal temperature over Armenia based on the Community Climate System Model 4 (CCSM4) output data from newly developed dataset of phase 5 of the Coupled Model Intercomparison Project (CMIP5) have been analysed. The results of this study suggest that Armenia will experience significant temperature increase in the twenty-first century. Moreover, the greatest warming is expected in the summertime and can reach 4–6 °C under representative concentration pathways (RCP)8.5 for the middle and end of the century. However, observations show significant variability and seasonal amplitude in temperature regime which is peculiar to mountain regions located in mid-latitudes. It was shown that strong cold wave events can be directly followed by prolonged hot days within one year in Armenia. The CCSM4 model has substantial deficiencies in simulating the regional climate over Armenia. Validation results indicate the largest errors (root-mean-square error (RMSE)) in the representation of winter temperatures. There is also significant uncertainty in projected temperature change patterns in Armenia over the twenty-first century. However, the CCSM4 model becomes more confident in the prediction of temperature increase over Armenia toward the end of the century.

Thermal and force modeling of CGI drilling

This paper presents a validated temperature distribution model that allows the prediction of temperature increase on a compacted graphite iron (CGI) workpiece during the drilling process. The thermal modeling procedure begins with the geometric modeling of inclination, rake, helix, and effective rake angles. Then, force models are evaluated for the chisel and cutting lip. The force model incorporates mechanistically calculated thrust force and torque values for varying inclination and rake angles on each divided tool segment. Divided segments are obtained by sectioning of the cutting edge, and they are named elemental cutting tools (ECTs). Force results are used to predict heat flux on the chisel, cutting lips, and the margin of the drilling tool. The heat flux values at the margin are optimized through numerical iteration between measured and calculated temperature values. The developed model is also verified experimentally. There is only a negligible difference between the measured and calculated temperature results. Finally, the temperature distribution on the workpiece is successfully obtained using numerical analysis.

Estimating the Genetic Capability of Different Phytoplankton Organisms to Adapt to Climate Warming

Current predictions of temperature increase in sea surface water estimate that extensive regions of the ocean will be warmer than at any time in the past million years as a consequence of the present trend of release the CO2 excess into the atmosphere. Studying the capacity of phytoplankton to adapt to warming has become a relevant issue because phytoplankton represents the basis of the aquatic food web supporting about half of the global primary production. Considering the complexity of the phytoplankton community in both taxonomic level and habitat preferences, different responses to increased temperature are expected.We experimentally estimate the potential of different phytoplanktonic populations of 15 species, belonging to different taxonomic groups (Cyanoprokaryota, Dinophyta, Chlorophyta, Haptophyta, Heterokontophyta) and habitat preferences(e.g. coastal waters, open ocean, coral symbiotic), to genetically adapt in an evolutionary sense to marine warming.Since genetic variance in fitness estimates capability for adaptation of a population (Fisher’s Fundamental Theorem of Natural Selection) we measured the heritability of fitness (i.e. proportion of variance in fitness that has genetic basis) under increasing temperatures, using an experimental quantitative genetic procedure suitable to phytoplankton populations. Our results reveal that there are interspecific differences in phytoplankton capability for adaptation under a gradual warming process and provides experimental evidences for assessing how phytoplanktonic organisms might evolve under climate warming in the near future.

Ear Temperature Increase Produced by Cellular Phones Under Extreme Exposure Conditions

This paper deals with the numerical prediction of temperature increase in the inner ear of subjects exposed to the electromagnetic (EM) radiation of conventional cellular phones. Attention has focused on the geometrical model of the internal ear organs and on including the intrinsic heating of the phone in the numerical thermal analysis. To this aim, infrared (IR) thermographic data have been used as time-variant Dirichlet boundary conditions (BCs) on the touching ear-phone boundary, while new convective BCs are applied on the cells not in contact. Numerical results, obtained by a finite difference (FD) procedure, showed a maximum temperature increase of about 4°C on the external ear, although significant thermal elevations were not observed in the most sensitive internal organs. These temperature rises are obtained under extreme exposure conditions, i.e., when forcing the phone at the maximum power of 250 mW for 30 min.

Prediction of Temperature Increase in Human Eyes Due to RF Sources

A numerical study is proposed to investigate the effects of different RF sources on the specific absorption rate (SAR) and maximum temperature increase in the human eye at different frequencies. In particular, a new model of the human head is presented and compared with an anatomical model of the visible human. The high resolution (0.5 mm) of the proposed model allows to consider more eye tissues than previous studies distinguishing the sclera from the retina and choroid. New values of blood perfusion and metabolic rate of these tissues are derived. A plane-wave field is considered as far-field exposure, while realistic models of mobile phone and dipole antennas are used as primary sources for near-field exposure. The obtained results show that the distributions of the SAR and temperature increase depend on the frequency, position, and kind of sources. Finally, attention is paid to the maximum temperature increase in the lens for the SAR values prescribed by the Commission on Non-Ionizing Radiation Protection. To this aim, a scaling approach is proposed, and significant values of temperature increase are found (about C for general public exposure and about 1.5 degC for occupational exposure) for the most critical cases of near-field exposures.

Surface heating by transvaginal transducers

This safety study was designed to investigate tissue heating close to the surface of transvaginal ultrasound transducers, with the objective of assessing the validity of manufacturing safety standards set by the International Electrotechnical Commission (IEC). The transducers investigated in this study were held in contact with a layered soft-tissue mimicking material (TMM), and the temperature increase was measured at various depths using a miniature thermocouple. The temperature rise at 200 s was recorded, and the measured profiles of temperature rise with depth were compared with profiles predicted from both analytical and numeric models. Two transvaginal transducers of different manufacturers were investigated, operating in B-mode imaging, color-flow imaging and pulsed Doppler modes, using scanner settings giving acoustic output power towards the upper end of that available. The greatest heating always occurred at the interface between the transducer and the TMM, and it reduced to about 0.1 times the surface temperature rise at a depth of 1 cm. A local maximum was observed in pulsed Doppler mode. A three-dimensional finite-element model which accounted for transducer dimensions gave a better prediction of temperature increase than a simple analytical model. The temperature profiles were compared with the depth of fetal tissue measured from a small survey of clinical scans. It is provisionally concluded that the transducer surface temperature rise of 6 degrees C allowed to manufacturers by the IEC may give rise to an associated worst-case contribution to temperature rise due to the transducer, in fetal tissue, of between 0.5 and 1 degrees C at 1-cm depth. The contribution to tissue heating at 2 cm and deeper is negligible. Published by John Wiley & Sons, Ltd.

The measurement and prediction of temperature increase in single catalyst pellets

Temperatures within and near to single pellets of tin/antimony oxide used to catalyse the oxidative dehydrogenation of butene to butadiene have been measured and the results compared with values predicted by a mathematical model. The observed temperature difference was up to 10°C, depending on the reaction conditions, with the major change in temperature occurring across the gas film near to the surface. The mathematical model describes these observations with reasonable accuracy, and discrepancies are discussed in terms of the parameters that are used in the calculation. The derived temperature difference is found to be particularly sensitive to values of bulk concentrations and film heat transfer coefficient, and to be less responsive to values of bulk density and effective diffusivity.