Thermal Gradient Distribution Research Articles

Harnessing geographic information system and street view imagery for thermal gradient distribution auditing

Harnessing geographic information system and street view imagery for thermal gradient distribution auditing

A Nanothermometer with a Microwave Thermal Effect for Sensing Cell Membrane Temperature and Measuring Microwave-Induced Thermal Gradient Distribution.

In microwave (MW) thermotherapy, it is challenging to regulate the temporal and spatial distribution of the temperature at the nanoscale. Herein, we report a nanothermometer for simultaneous MW heating and temperature distribution measurement. The nanothermometer was prepared by free radical polymerization with vinylbenzyl trimethylammonium chloride (VBTMACl) as the MW thermosensitizer and isopropylacrylamide (NIPAM) as the thermoresponsive unit, followed by anion exchange with fluorophore sodium 3-(4-(1,2,2-triphenylvinyl)phenoxy)propane-1-sulfonate (TPESO3Na). In aqueous medium, the nanothermometer self-assembles into micelles with TPESO3- as the hydrophobic core and thermoresponsive polymer P(NIPAM-co-VBTMACl) as the hydrophilic shell, thereby to exhibit aggregation-induced emission (AIE). By increasing the temperature, the conformational change of the thermoresponsive polymer drives TPESO3- to transfer from the core to the shell of the micelles, and the nanothermometer converts from an aggregate state to a dispersed state. As a result, the nanothermometer exhibits a superior temperature-dependent emission feature in the temperature range 25-41 °C, with a relative thermal sensitivity of 8.3% °C-1 at 37 °C. In addition, the nanothermometer possesses a positive charge and balanced hydrophilic-hydrophobic feature which prompts its anchoring to the cell membrane. Therefore, it realizes in situ temperature sensing of cell membranes during MW heating, as well as temperature distribution of the cell membrane.

Plants transpiration-inspired antibacterial evaporator with multiscale structure and low vaporization enthalpy for solar steam generation

Solar-driven vapor generation by localized solar heating of a photothermal material is an environmentally friendly approach for seawater desalination and wastewater purification. In this work we designed a novel bionic evaporator, inspired by plant transpiration in nature, to realize highly efficient solar vapor generation. The plant transpiration inspired three-dimensional structure has a hydrophilic cellulose skeleton with high porosity and low thermal conductivity, and decorated with photothermal polypyrrole (PPy) that self-organize as nano branches and leaves exhibiting excellent photothermal conversion capacity. The cellulose skeleton has microchannels that facilitates water transport and reduces the water evaporation enthalpy. PPy nano branches and leaves can not only efficiently absorb and convert sunlight, but the thermal gradient distribution in this microstructure induces Marangoni convection which guarantees efficient water transportation in evaporative regions. Moreover, the coupling of external wind fields further enhances the rate of vapor escape. The as-fabricated vapor generator based on the bionic structure achieved an impressive high evaporation rate of 2.05 kg m−2 h−1 under one sun (1 kW m−2) irradiation, with the solar thermal conversion efficiency up to 97.7%. A significantly higher water vapor generation rate of 2.9 kg m−2 h−1 is obtained under one sun irradiation at a wind speed of 2 m s−1. In addition, the evaporator has excellent photothermal antibacterial activity against both E. coli and S. aureus. This bionic evaporator offers a potential low-cost and highly efficient water purification technology that could help mitigate the global water crisis.

Long-Term Impacts of Temperature Gradients on a Concrete-Encased Steel I-Girder Experiment—Field-Monitored Data

This article delves into an investigation of an experimental steel I-girder section encased in concrete and its instrumentation for the purpose of analyzing temperature distributions in concrete bridges. The study aims to examine the effect of differing air temperatures and thermal loads resulting from solar radiation. Structural health monitoring sensors, including a range of temperature sensors, were connected with the girder to monitor the structural performance using the data acquisition system constantly. The collection of experimental data took place during an exceptionally cold season, and the results of the study revealed both the lateral and vertical distribution of thermal gradients, as well as the fluctuations in these gradients over time. On the premise of the accumulated thermal data, empirical equations were suggested in order to forecast peak lateral as well as vertical temperature gradients, in accordance with the girder’s highest daily and lowest mean temperatures. This temperature variation may lead to longitudinal expansion and contraction in the structure during seasonal variations.

Thermal monitoring of laser metal deposition strategies using infrared thermography

The thermal monitoring of additive manufacturing techniques implementing high-power energy sources is essential to ensure process quality. Although the number of research works on thermal process monitoring has grown in recent years, there are still few works that focus on using thermal camera monitoring on Laser Metal Deposition (LMD), to analyze thermal effects caused by changes in deposition strategy. This work aimed to monitor the entire thermal field produced by the LMD process during the multitrack deposition of a Nickel-based superalloy. The temperature field monitoring was carried out using an IR thermal camera capable of detecting temperatures up to 2117 °C. Experimental tests were carried out on six deposition strategies, showing that for unidirectional hatch strategies maximum temperatures of 1620 °C were reached, while contouring strategies exceeded 2100 °C. The thermographic map assessed the spatial distribution of the temperature generated by each strategy. Moreover, some key points are chosen to analyze the thermal cycles and relative cooling rates generated during the process. Additionally, an ad-hoc algorithm was elaborated to calculate the thermal gradient of every frame acquired by the thermal camera, and a routine was elaborated to create the thermal gradient map. The thermal gradient profiles were evaluated, showing mean values around 550 °C/mm and marked variations (between 200 and 700 °C/mm) only for contouring strategies. The thermal characteristics are then correlated with the metallographic and microhardness analyses. A high number of cracks was found in areas with higher temperature and thermal gradient variations. Finally, microhardness tests were carried out, and mean values and standard deviations were correlated with the thermal gradient distribution.

Static and dynamic analyses of FGPM cylindrical shells with quadratic thermal gradient distribution

Functionally graded material (FGM) has great potential in the application of thin-walled structures, since delamination failure can be suppressed. Functionally graded piezoelectric material (FGPM) is a special kind of FGM, which couples with elastic and electric fields. The modeling of FGPM coupled smart structures under nonlinear thermal load is still a challenge task. This paper develops an electro-thermo-elastic finite element (FE) model of FGPM integrated smart structures based on the first-order shear deformation hypothesis. The FE model proposes two different nonlinear configurations of thermal gradient distribution through the thickness, which are compared with linear thermal gradient distribution. An eight-node quadrilateral shell element is developed for finite element analysis. The present FE model is firstly validated by a PVDF bimorph beam under nonlinear thermal loads. Later, the model is applied to the static and dynamic simulation of FGPM cylindrical shells. The results show that thermal distribution configurations have great impact on structural response, which should be carefully chosen in the simulation of thermal coupled problems.

A 3D model of the thermal field within the Polish Carpathians and the Carpathian Foredeep (S Poland)

Numerical 3D parametric models of temperature and thermal gradient distribution within the Polish Carpathians and the Carpathian Foredeep are constructed for the interval between ground level and the 160°C isotherm. The model construction was preceded by detailed analysis of over 500 thermal logs from the area investigated and its closest vicinity. This analysis showed that the vertical changes in temperature and thermal gradient have a non-linear character with no regular pattern in the distribution of the parameters modelled, so a 3D modeling approach was chosen as the most appropriate method for their quantitative description. Furthermore, standardization of the thermal logs was recognized as mandatory so the influence of drilling process would be eliminated. Among a broad array of methods and their preconditions discussed, the Kukkonen-Szewczyk method was selected for the data collected in the study area. Modeling results show a close relationship between thermal gradient, lithology and petrophysical rock properties as well as a correlation between the distribution of positive thermal anomalies and yield of hydrocarbon accumulations within the Carpathian Foredeep. The accuracy of the model has been assessed as ~10%. The model was then used for discussion of hydrocarbon generation and prediction of formation temperature.

Estimation of Heat Flow Using a Bottom Simulating Reflection Based on 3D Seismic Data, West Africa

DOI:10.17014/ijog.8.3.297-311A Bottom Simulating Reflection (BSR) has been identified using 3D seismic data from the Cameroon continental slope margin. The BSR covers an area of c. 350 km2 in water depths ranging between 940 m to 1,750 m across an area characterized by high- and low-gradient slopes, gullies, scours, and fans. The thickness of the Gas Hydrate Stability Zone (GHSZ) is ~100 - 250 m, assuming an average velocity of 1,800 m/s. Pockmarks are intensively developed across the slope and most of them are observed in the BSR area. Geothermal estimation is based on hydrate stability conditions for pure methane - seawater system, hydrostatic pressure model, and a range of P-wave velocity models for the GHSZ, ranging from 1,600 -1,800 to 2,000 - 2,200 m/s. Geothermal gradient is calculated showing the range and distribution of thermal gradients in the BSR area from 0.046 C/m to 0.094 oC/m with assumed GHSZ velocity of 1,800 m/s. Thermal gradient anomalies have been observed in association with gullies, vertically stacked channels and in some individual pockmarks. The highest anomalies of 0.08 C/m – 0.094 C/m are found in the depression areas of pockmark trains, within seafloor gullies. These positive anomalies are most likely controlled by active or recently active fluid advection and expulsion through the Cameroon slope.

Thermally-Compensated High Power Nd: YAG Slab Laser Module With Low Wavefront Distortion

A low-order wavefront aberration self-compensation high power Nd:YAG slab laser module is developed and demonstrated. By numerical simulating the thermal distribution and transmission wavefront of the slab laser medium, a thermally-compensated heat removal geometry is developed to reduce the wavefront distortion. This method allows the non-uniform cooling to flatten the thermal gradient distribution in the width direction of the slab. By using the optimized gain module as an amplifier, the laser output power of 7.8 kW is achieved. Compared to the traditional module, the output power is 7.3 kW, and the peak-to-valley (PV) value of the wavefront distortion is reduced from 17.21 to $2.05~\mu \text{m}$ under full power, the beam quality factor $\beta $ is improved from 12.7 to 3.5 times diffraction limited while without additional correction system.

Integrated Computational Materials Engineering to Predict Melt-Pool Dimensions and 3D Grain Structures for Selective Laser Melting of Inconel 625

This work presents a comparison of simulation results with the experimental data for four of the six challenges within the National Institute of Standards and Technology (NIST) Additive Manufacturing (AM) Benchmark Test Series (AM Bench) problem AMB2018-02. This comparison is akin to a test case to assess the technology maturity level (TML) for the AM predictive capabilities that can be utilized to improve AM products in the industry. The solutions are for the prediction of melt-pool geometry, cooling rate, solidification grain shapes, and their 3D structure. These results were obtained using the Additive Manufacturing Parameter Predictor (AMP2) software. AMP2 is an Integrated Computational Materials Engineering (ICME) suite of software developed by Applied Optimization, Inc. (AO). The melt-pool geometry is obtained using a thermal-computational fluid dynamics (CFD) solution of melt-pool physics. The melt-pool geometry, mean track cross section, 3D distribution of thermal gradient, and the liquid-to-solid interface velocity are predicted by the thermal-CFD model and utilized as input for the solidification grain structure computation. The grain shapes and 3D structure are modeled using cellular automata (CA). AO received a second-place award for predicting the grain structure within three single laser tracks on a bare plate of alloy Inconel 625 (IN625).

Mathematical Modeling of Transport Phenomena in Multi-track and Multi-layer Laser Powder Deposition of Single-Crystal Superalloy

The transport phenomena in the multi-track and multi-layer laser powder deposition process of single-crystal superalloy were studied through an improved three-dimensional transient mathematical model. The effect of overlapping ratio on the transport phenomena such as temperature field, molten pool morphology, and thermal gradient distribution was discussed. Laser powder deposition experiments with single-crystal superalloy were conducted to verify the computational results. Results showed that temperature field and molten pool morphology are symmetric in the first track of the first layer, and then become asymmetric in the following tracks and layers due to the overlapping between tracks. The peak temperature in a layer increases quickly in the first three tracks and then gradually tends to steady state. For the same track number, the peak temperature in the second layer is higher than that in the first layer. The overlapping ratio has a predominant influence on the molten pool morphology and the distribution of normal thermal gradient at the solidification interface. With the increase of overlapping ratio, the melting depth of molten pool decreases, while the height of molten pool increases. Good agreement was obtained between the predicted and experimentally results. Under the given processing parameters, continuous epitaxial columnar dendrites were achieved in multi-track and multi-layer laser deposited SX superalloy with the optimized overlapping ratio = 34 pct.

Thermal Gradient During Vacuum-Deposition Dramatically Enhances Charge Transport in Organic Semiconductors: Toward High-Performance N-Type Organic Field-Effect Transistors.

A thermal gradient distribution was applied to a substrate during the growth of a vacuum-deposited n-type organic semiconductor (OSC) film prepared from N,N'-bis(2-ethylhexyl)-1,7-dicyanoperylene-3,4:9,10-bis(dicarboxyimide) (PDI-CN2), and the electrical performances of the films deployed in organic field-effect transistors (OFETs) were characterized. The temperature gradient at the surface was controlled by tilting the substrate, which varied the temperature one-dimensionally between the heated bottom substrate and the cooled upper substrate. The vacuum-deposited OSC molecules diffused and rearranged on the surface according to the substrate temperature gradient, producing directional crystalline and grain structures in the PDI-CN2 film. The morphological and crystalline structures of the PDI-CN2 thin films grown under a vertical temperature gradient were dramatically enhanced, comparing with the structures obtained from either uniformly heated films or films prepared under a horizontally applied temperature gradient. The field effect mobilities of the PDI-CN2-FETs prepared using the vertically applied temperature gradient were as high as 0.59 cm2 V-1 s-1, more than a factor of 2 higher than the mobility of 0.25 cm2 V-1 s-1 submitted to conventional thermal annealing and the mobility of 0.29 cm2 V-1 s-1 from the horizontally applied temperature gradient.

Behavior of prestressed concrete box bridge girders Under hydrocarbon fire condition

Abstract Currently, prestressed concrete (PC) bridges are often suffered from fire caused by oil tanker. However, there is very little research information and test data in the literature on the fire resistance of PC bridge girders. This paper presents an investigation into behavior of PC box bridge girder under hydrocarbon fire condition. A numerical model, in the form of the computer program ANSYS, for predicting the influence of a significantly critical factor, namely, prestress degree, on the performance of prestressed concrete bridge with box girder subjected to hydrocarbon fire is presented. The three stages associated with the numerical procedure, for evaluating fire resistance of PC box girders, namely, fire temperature calculation; cross-sectional thermal gradient evaluation and determination of mechanical response in box girders are elucidated. A simplified approach to account for thermal gradient distribution within girder section and deformations of PC box girder under hydrocarbon fire condition is incorporated into the FEM model. The applicability of the computer program for evaluating the fire resistance of PC box girder, resulting from combined effect of thermal and mechanical loading, is demonstrated through a case study. Through the numerical analysis results of case study, it is shown that different prestress degree adopted in girders has significant influence on the fire resistance of PC bridges.

Effects of Substrate Crystallographic Orientations on Microstructure in Laser Surface-Melted Single-Crystal Superalloy: Theoretical Analysis

A geometric analysis technique for crystal growth and microstructure development in single-crystal welds had been previously developed. And the effect of welding conditions on the tendency of stray grains formation during solidification was researched. In the present work, these analytical methods were further extended. Combined with an original vectorization method, a 3D Rosenthal solution was used to determine thermal conditions of the welds. Afterward, the dendrite growth orientation, the dendrite growth velocity and the thermal gradient along dendrite direction were calculated and lively plotted. Finally, the tendency of stray grains formation in the solidification front was forecasted and its distribution was presented with a 3D plot. The results indicate that substrate orientation has some impacts on the crystal growth pattern, dendrite growth velocity, distribution of thermal gradient and stray grain. Based on the research methods proposed in this work, any substrate crystallographic orientation can be studied, and predicted stray grains distribution can be visualized.

Present-Day Heat Flow, Thermal History, and Tectonic Subsidenceof the Jianghan Basin

Thermal gradient distribution of the Jianghan Basin is obtained based on systematic steady-state and oil-test temperature data. The present geothermal gradient and terrestrial heat flow of 18 wells are calculated in the Jianghan Basin. A total of 9 measured terrestrial heat flow values are reported based on detailed thermal conductivity data and systematic steady-state temperature data. These values vary from 41.9 to 60.9 mW/m2, with a mean value of 52.3 ± 6.3 mW/m2. However, thermal history analyses, derived from vitrinite reflectance (RO) and apatite fission track (AFT) data, indicate that the Jianghan Basin was at a stable stage before the Indosinian movement. The heat flow increased and reached its maximum value of ∼68 mW/m2 during the Late Indosinian to Early Yanshan period. Since the Late Himalayan period, rapidly decreasing basement heat flow made the Jianghan Basin cool down. Furthermore, geohistory analysis reveals that the tectonic subsidence of the Jianghan Basin from the Cretaceous to Early Miocene was characterized by initial synrift subsidence followed by thermal subsidence. The thermal and tectonic subsidence history have directly effects on petroleum source rock maturation, so their analyses are of great significance forpetroleum exploration and hydrocarbon source assessment in the Jianghan Basin.

Possibilities of the Materials Properties Improvement for the Cementite Eutectic by Means of Unidirectional Solidification

Abstract The paper brings the results of directional solidification of Fe-Fe3C eutectic alloy. The Bridgman method with vertical thermal gradient in conducted research was applied. Two values of rate was used for sample movement testing. One sample after solidification, was immediately taken of the cooler. The distribution of thermal gradient in the alloy was determined. The value of thermal gradient in liquid at the solidification front was determined. On the samples, where cementite eutectic was oriented, interphase spacing λ̅ was measured. The results of the dependence between parameters v and λ̅ were presented. The research with application of optical microscope and computer programme to image analysis NIS-Elements was used.

Disentangling thermal preference and the thermal dependence of movement in ectotherms

Many ectotherms thermoregulate by choosing environmental temperatures that maximize diverse performance traits, including fitness. For this reason, physiological ecologists have measured preferred temperatures of diverse ectotherms for nearly a century. Thermal preference is usually measured by observing organism distributions on laboratory thermal gradients. This approach is appropriate for large ectotherms which have sufficient thermal inertia to decouple body temperatures from gradient temperatures. However, body temperatures and therefore speeds of movement of small ectotherms will closely track gradient temperature, making it difficult to distinguish between thermal preference and thermal dependence of movement. Here we develop and demonstrate the use of a patch model to derive the expected thermal gradient distribution given only the thermal dependence of movement. Comparison of this null distribution with the observed gradient distribution reveals thermal preference of small ectotherms.

Geothermal regime and hydrocarbon kitchen evolution in the Jianghan Basin

The present geothermal gradient and terrestrial heat flow was calculated of 18 wells in the Jianghan Basin. Thermal gradient distribution of the Jianghan Basin was obtained based on data of systematical steady-state temperature and oil-test temperature. The basin-wide average thermal gradient in depth interval of 0–4000 m is 33.59°C/km. We report nine measured terrestrial heat flow values based on the data of detailed thermal conductivity and systematical steady-state temperature. These values vary from 41.9 to 60.9 mW/m2 with a mean of 52.3 ± 6.3 mW/m2. However, thermal history analyses based on vitrinite reflectance (VR) and apatite fission track (AFT) data indicate that thermal gradient in the northern and southern Qianbei Fault reached its peak of ∼36 and ∼39°C/km respectively in the Middle Jurassic and the Oligocene, and it descended during the early Miocene to the present-time value. Furthermore, tectonic subsidence analysis reveals that the tectonic subsidence of the Jianghan Basin in the Cretaceous to early Miocene was characterized by synrift initial subsidence followed by the subsequent thermal subsidence. The thermal history and tectonic subsidence history of Jianghan Basin are of great significance to petroleum exploration and hydrocarbon source assessment, because they bear directly on issues of petroleum source rock maturation. Based on the thermal history and tectonic subsidence history, with the combination of geochemical and thermal parameters, the maturation and the hydrocarbon generation intensity evolution history of the P2 d source rocks are modeled. The results show that the P2 d source rocks are in a higher degree of maturation at present, and the Yuan’an and Herong sags are the two most important kitchens in the Late Jurassic, Xiaoban Sag is another most important kitchen during the Late Cretaceous to late Paleogene, and the Zhijiang and Mianyang sags are other two important hydrocarbon kitchens in the Late Cretaceous. The Mianyang Sag and Yichang Ramp are the favorable exploration targets in the future. This study may provide new insight for the understanding of the oil and gas exploration potential for the Jianghan Basin.

Geothermal regime and hydrocarbon kitchen evolution of the offshore Bohai Bay Basin, North China

The offshore Bohai Bay Basin, located in the central Bohai Bay Basin, north China, one of the most petroliferous basins in China. In this article, based on formation-testing temperature, drill-stem tests, and bottom-hole temperature data, 80 thermal gradient values at the depth interval of 0 to approximately 3000 m (~9843 ft) in the offshore Bohai Bay Basin were obtained. The basinwide average thermal gradient is 31.8 4.6C/km. Based on the above thermal gradient data and the corresponding average weighted thermal conductivity data, 80 measured terrestrial heat flow values were obtained. These values range from 33.5 to 84.0 mW/m2, with an average value of 60.8 8.7 mW/m2. The heat flow and thermal gradient distribution in this region generally show higher values in the uplifts and lower ones in the sags. A thermal history, derived from vitrinite reflectance and apatite fission-track) data, indicates that Paleogene cooling occurred after a period of much higher paleogeothermal gradient (3854C/km). Tectonic subsidence analysis reveals that the area experienced initial synrift subsidence during the Paleogene followed by subsequent thermal subsidence since the Neogene. Thermal and tectonic subsidence histories of this area are of great significance to petroleum exploration and hydrocarbon resource assessment because they bear directly on issues of petroleum source rock maturation. The maturation and hydrocarbon expulsion histories of the Paleogene Shahejie 3 Formation (E2s3), which is the most important source rock in the offshore Bohai Bay Basin, are modeled. Results show that the Shahejie 3 Formation is in a high mature stage at the present day, and the Bozhong and Qikou sags are the most important kitchens. The Huanghekou sag became the third most important hydrocarbon kitchen in the early Neogene. Based on this hydrocarbon kitchen evolution, oil and gas mainly accumulated after 12 Ma. The evolution of kitchen areas may provide new insights for the understanding of the oil and gas exploration potential of the offshore Bohai Bay Basin.

Geothermal regime and Jurassic source rock maturity of the Junggar basin, northwest China

We analyze the thermal gradient distribution of the Junggar basin based on oil-test and well-logging temperature data. The basin-wide average thermal gradient in the depth interval of 0–4000 m is 22.6 °C/km, which is lower than other sedimentary basins in China. We report 21 measured terrestrial heat flow values based on detailed thermal conductivity data and systematical steady-state temperature data. These values vary from 27.0 to 54.1 mW/m 2 with a mean of 41.8 ± 7.8 mW/m 2. The Junggar basin appears to be a cool basin in terms of its thermal regime. The heat flow distribution within the basin shows the following characteristics. (1) The heat flow decreases from the Luliang Uplift to the Southern Depression; (2) relatively high heat flow values over 50 mW/m 2 are confined to the northern part of the Eastern Uplift and the adjacent parts of the Eastern Luliang Uplift and Central Depression; (3) The lowest heat flow of smaller than 35 mW/m 2 occurs in the southern parts of the basin. This low thermal regime of the Junggar basin is consistent with the geodynamic setting, the extrusion of plates around the basin, the considerably thick crust, the dense lithospheric mantle, the relatively stable continental basement of the basin, low heat generation and underground water flow of the basin. The heat flow of this basin is of great significance to oil exploration and hydrocarbon resource assessment, because it bears directly on issues of petroleum source-rock maturation. Almost all oil fields are limited to the areas of higher heat flows. The relatively low heat flow values in the Junggar basin will deepen the maturity threshold, making the deep-seated widespread Permian and Jurassic source rocks in the Junggar basin favorable for oil and gas generation. In addition, the maturity evolution of the Lower Jurassic Badaowan Group (J 1b) and Middle Jurassic Xishanyao Group (J 2x) were calculated based on the thermal data and burial depth. The maturity of the Jurassic source rocks of the Central Depression and Southern Depression increases with depth. The source rocks only reached an early maturity with a R 0 of 0.5–0.7% in the Wulungu Depression, the Luliang Uplift and the Western Uplift, whereas they did not enter the maturity window ( R 0 < 0.5%) in the Eastern Uplift of the basin. This maturity evolution will provide information of source kitchen for the Jurassic exploration.