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Large-format prismatic Li-ion batteries (LIBs) are prominent energy storage devices in electric transportation applications. However, large-format LIB induces severe thermal runaway (TR) disasters. Battery failure commonly initiates from a local point of one jelly roll and then propagates to the whole cell, called thermal runaway front (TRF) propagation. This study investigates the TRF propagation mechanism of multi-jelly roll-based LIBs through experiments, modeling, and theoretical analysis for thermal runaway propagation (TRP) mitigation. Experiments prove that battery venting changes along the jelly roll-safety valve directions during the TRF boundary movement. Besides, TRF propagation speed is found to be accelerated inside each cell (from 3.6 to 10.6 mm/s) during TRP, driven by a significant temperature gradient, chemical reactions, and gas flow along the TRP direction. The in-cell TRF acceleration behavior is more noticeable for batteries with more jelly rolls. The TRF speed-jelly roll index equations are proposed to reveal the propagation acceleration principle mathematically. Furthermore, a thermal-physical model is developed to precisely simulate in-cell TRF propagation behavior, which is validated by experimental data. Moreover, the TRF boundary temperature equation and "No TRP" judging criteria are proposed through theoretical analysis. This study proposes promising strategies for potential TRP suppression, contributing to future safe battery system design. [ABSTRACT FROM AUTHOR]

In this work, a detailed analysis and thermal modeling for temperature prediction of a stand-alone photovoltaic module is performed. The study aims to present precise estimation of module temperature, since it is an important parameter for power output calculation. Hence, the required data were collected via experiments. Accounting for all heat transfer mechanisms, and following model validation, a proposed algorithm was implemented to investigate heat transfer from the module to its surrounding and predict different layers' temperature. Results indicate that accurate energy distribution and temperature prediction was achieved by the adopted thermal model, only about 16 % of the received energy is converted to electrical power while the rest is released by heat. Moreover, the proposed simulation algorithm provided one of the best results in comparison to literature models, achieving an R 2 of 0.963 and a M A E of 1.883 , which is very close to the best overall model by King at R 2 = 0.973 and M A E = 1.663. Additionally, two new models for module temperature prediction were proposed. After testing on new data, the explicit model provided a reasonable first approximation attaining an adjusted R 2 of 0.97 and a M S E of 3.505 , and an accurate implicit model, achieving a M S E of only 1.268. [ABSTRACT FROM AUTHOR]

Welding-induced residual stresses play a critical role in fitness-for-service evaluation of pressure equipment as stipulated by codes and standards, e.g., BS 7910 and API 579 RP-1/ASME FFS-1. Due to the complex residual stress evaluation process, two-dimensional (2D) residual stress modeling is most often exercised for supporting the development of the residual stress prescriptions in these FFS codes. Two major limitations exist in such a 2D modeling approach. One is the lack of heat sink effects in the third direction, resulting in a missing linkage to the actual welding linear heat input. The other is the over-simplifications of the mechanical restraint effects on the residual stress development process by imposing generalized plane-strain or axisymmetric conditions. This paper presents a physically consistent 2D residual stress model, with which actual welding linear heat input can be consistently interpreted for use in a 2D thermal model and 3D mechanical restraint effects can be approximated through a set of closed-form expressions that can be readily implemented in available finite element procedures. The effectiveness of the proposed 2D modeling procedures is then validated against a few well-documented residual stress case studies on which experimental data are available. • A novel 2D residual stress modeling procedure is presented for consistently approximating 3D effects. • A linear welding heat input estimation procedure is proposed for relating 2D model to 3D welding conditions. • A sub-domain definition is introduced for approximating the effects of mechanical restraints on 2D residual stress model. • The proposed 2D residual stress model can be cost-effectively used for supporting FFS assessment. [ABSTRACT FROM AUTHOR]

Determining both the average temperature and the underlying temperature distribution within a battery system is crucial for system design, control, and operation. Therefore, thermal battery system models, which allow for the calculation of these distributions, are required. In this work, a generic thermal equivalent circuit model for commercial battery modules with passive cooling is introduced. The model approach can be easily adopted to varying system designs and sizes and is accompanied by a corresponding low-effort characterization process. The validation of the model was performed on both synthetic and measured load profiles from stationary and marine applications. The results show that the model can represent both the average temperature and the occurring temperature spread (maximum to minimum temperature) with deviations below 1 K. In addition to the introduced full-scale model, further simplifying assumptions were tested in order to reduce the computational effort required by the model. By comparing the resulting simplified models with the original full-scale model, it can be shown that both reducing the number of simulated cells and assuming electrical homogeneity between the cells in the module offer a reduction in the computation time within one order of magnitude while still retaining a high model accuracy.

We designed a 3D geometrical model of a metal-oxide gas sensor and its custom packaging and used it in finite element modeling (FEM) analysis for obtaining temperature and heat flux distribution. The 3D computer simulation, performed with GetDP software (version 3.5.0, 13 May 2022), accurately predicted the temperature distribution variation across the entire assembly. Knowing the temperature variation and the location of the hot spots allowed us to select the best electrical interconnect method and to choose the optimal materials combination and optimal geometry. The thermal modeling also confirmed the need to use a low thermal conductivity material to insulate the MOX sensor since the latter is heated to its operational temperature of 250 °C. For that purpose, we used the in-house formulated xerogel–epoxy composite of thermal conductivity of 0.108 W m−1 K−1, which is at least 30% less compared to the best-in-class among commercially available materials. Based on the 3D FEM outputs, we designed, assembled, and characterized a fully functional packaged MOX gas sensor in several configurations. We measured the temperature distribution on all parts of the MOX gas sensor assembly using a thermal imaging infrared (IR) microscope. The results of 3D FEM are in good agreement with the temperature distribution obtained by the non-contact IR thermal characterization.

In this paper, we trace the thermal history of the mafic–ultramafic intrusions of the Monchegorsk (MC), Fedorova–Pana (FPC), and Norilsk ore-bearing complexes (NC) using an upgraded version of the author’s software Gehenna 2.2. It is shown that a key role in the concentration of sulfides in the lower parts of the intrusions belongs to the preliminary heating of the host rocks by early magmatic influxes. In the presence of late ore-bearing magmatic phases of a relatively small volume, the pattern of sulfide distribution within such a phase can be used to estimate the time gap with the main influx. Thermal modeling shows that the Gabbro-10 massif, an additional ore-bearing phase of the Nyud-Poaz intrusion of the MC, is separated from the main influx by a time gap of no more than 100 ka, while the minimum gap between the magmatic phases of the Fedorova intrusion of the FPC is 650–700 ka. The development of a hornfels halo around mafic–ultramafic rocks makes it possible to estimate the duration of the process of continuous magma flow inside intrusions, which, as an example from the Kharaelakh intrusion of the NC shows, can reach 1000 years and more. Thermal modeling is recommended both for formulating genetic hypotheses and for testing different scenarios for the formation of sulfide Cu-Ni-PGE mineralization in mafic–ultramafic complexes.

To enhance our understanding of the thermal characteristics of lithium-ion batteries and gain valuable insights into the thermal impacts of battery thermal management systems (BTMSs), it is crucial to develop precise thermal models for lithium-ion batteries that enable numerical simulations. The primary objective of creating a battery thermal model is to define equations related to heat generation, energy conservation, and boundary conditions. However, a standalone thermal model often lacks the necessary accuracy to effectively anticipate thermal behavior. Consequently, the thermal model is commonly integrated with an electrochemical model or an equivalent circuit model. This article provides a comprehensive review of the thermal behavior and modeling of lithium-ion batteries. It highlights the critical role of temperature in affecting battery performance, safety, and lifespan. The study explores the challenges posed by temperature variations, both too low and too high, and their impact on the battery’s electrical and thermal balance. Various thermal analysis approaches, including experimental measurements and simulation-based modeling, are described to comprehend the thermal characteristics of lithium-ion batteries under different operating conditions. The accurate modeling of batteries involves explaining the electrochemical model and the thermal model as well as methods for coupling electrochemical, electrical, and thermal aspects, along with an equivalent circuit model. Additionally, this review comprehensively outlines the advancements made in understanding the thermal behavior of lithium-ion batteries. In summary, there is a strong desire for a battery model that is efficient, highly accurate, and accompanied by an effective thermal management system. Furthermore, it is crucial to prioritize the enhancement of current thermal models to improve the overall performance and safety of lithium-ion batteries.

There has been a significant increase in demand for electric vehicles (EVs) in recent times due to existing environmental situations and an ever rising concern for energy. Due to the electrification of transportation and customer requirement, there is a concentrated focus on vehicle performance of EVs as a prime criterion. Amongst performances, range anxiety caused by the poor energy densities of the batteries, is one of the major drawbacks in these EVs. Possible mitigation for these scenarios includes, increasing the battery capacity, using dual energy sources and/or optimising the energy demands. After the propulsion system, auxiliary systems have an immense impact on the energy demands, the most significant being the heating ventilation and air-conditioning (HVAC) unit. With that in mind, this study develops a thermal model to analyse the required HVAC power for varying vehicle specifications. To benefit from the simplicity and versatility of one-dimensional $(1D)$ numerical models, the passenger cabin of a city bus was modelled in Matlab Simulink. Next, empirical relations were employed to take external convection, wall conduction, solar radiation and passenger heat generation into account. Additionally, the influence of the forced internal convection of the conditioned air flow in the passenger cabin was modelled and analysed in a three-dimensional $(3D)$ CFD simulation and then transferred into the $1D$ model. The results of the CFD simulation were also used to validate the $1D$ model in early stages of development. The model was then used to examine the effect of insulation and reflectivity optimization on the HVAC power consumption at different vehicle speeds. To the best of our knowledge, the model developed in this paper can be used to evaluate the required HVAC power, thus maintaining a required cabin temperature for various heavy vehicle specifications as well as boundary conditions.

In this study, a metaheuristic-based method, called Balanced Water Strider Optimization Algorithm (BWSOA), is presented to predict the thermal variables of a building. The measurement of these variables is not easy and the determination of them by features of materials is difficult. Also, it depends on the building type and the structure of the building The variable prediction problem is calculated as a single-objective optimization problem and the DesignBuilder™ is utilized to design the thermal model, which is a black-box here. The simulated and practical energy usage data of the building is utilized to show the operation of the suggested model by employing the model to two various geographical conditions placed in New Zealand. The algorithm performance is more showed by assuming simulated energy usage data; made after subjecting the thermal model of the building to a simulated geographical environment of another city (Tauranga); with the considerable various weather condition in comparison to that of Wellington. The obtained results stated that the suggested method can estimate these variables efficiently. Moreover, this approach can be efficient to develop energy management systems for the building.

In this work, a thermal Finite Element model is developed to simulate the performance of a blade-like tool for robotic work cells performing automated garment production using a novel thermoplastic stiffening layer. Uncertainty quantification and sensitivity analysis are applied to determine the most important design properties and optimize key performance metrics for swift and reliable garment assembly. Attention is focused on the geometric and thermal design properties that minimize sensitivity to environmental conditions while maximizing expected productivity. An example design is shown for illustrative purposes. This work may inform future design innovation for similar heating tools and reduce the need for physical experiments and long calibration times on the factory floor. [ABSTRACT FROM AUTHOR]

Insulated gate bipolar transistor (IGBT) modules with multiple chips have wide range of applications, and the correct estimation for the thermal behaviors inside IGBT modules is becoming crucial. Thermal impedance matrix is one of the most adopted approaches to describe the thermal-coupling effect of IGBT module. For simplicity of analysis, the heatsink or ambient temperature is typically chosen as the reference node for the thermal-coupling impedance term, while the case temperature is simplified or ignored. This letter provides a thermal coupling model enabling case temperature as reference node. This proposed model decouples the thermal coupling impedances of IGBT module itself and external cooling condition, so that the modeling of cooling conditions outside device and inside the power module, can be separately considered. The characterization method and advantages of the proposed model are verified by an experimental demonstration, and the potential applications are further discussed. [ABSTRACT FROM AUTHOR]

An investigation has been done to identify the heat source model suitable for numerical modeling of the Gas Metal arc Welding (GMAW) welding process. In the present investigation, a numerical model was constructed to simulate the GMAW welding process through transient thermal analysis for different thermal heat source models for weld deposition of Mild steel considering semi-cylindrical weld bead geometry. The Gaussian heat source with radial coordinate system and double ellipsoidal thermal heat source have been considered to develop a Finite Element Analysis (FEA) model. Validation of numerical analysis results has been confirmed through experimental investigation. Numerical modeling confirms the utilization of both heat sources, i.e. Gaussian and Double ellipsoidal for the prediction of the weld bead deposition profile. However, the numerical modeling developed using a double ellipsoidal heat source has more resembles experimental investigation due to the utilization of bead profile data. However, the Gaussian heat source is found to be suitable in the case of the unavailability of experimental data. The experimental studies show a variation in the weld bead geometry, along its welding direction due to multiple environmental factors. The microstructural investigation also shows the development of a fine columnar grain structure at the welding bead & weld penetration zone, and the grain structure became coarser at the Heat Affected Zone (HAZ). [ABSTRACT FROM AUTHOR]

In the design process of power electronics converters, the power semiconductors thermal modeling is one of the most critical tasks. An accurate estimation of the junction temperature allows the validation of the converter design and also the calibration of the thermal models during prototyping. Therefore, this article presents a straightforward method to estimate the junction temperature directly on the target converter using a plug-in measurement system. The estimation is based on the IGBT on-state voltage measurement under high current with a dedicated sensing circuitry externally connected to the converter under test. This solution is specifically designed to fulfill the needs during the prototyping process and design validation since allows a fast and reliable monitoring in all working conditions of interest and the sensing circuitry does not affect the normal operation of the converter under test (CUT). The acquisition circuitry and the calibration procedure are described and tested on a 68-kVA IGBT industrial three-phase inverter. The experimental results obtained on the target inverter prove that the proposed design validation based on the implemented estimation of the junction temperature provides better results than the conventional design methods based on thermal models implemented in simulators. [ABSTRACT FROM AUTHOR]

SiC MOSFETs have received great attention due to their excellent electrothermal properties. Accurate junction temperature information of SiC MOSFETs ensures safe operation and helps effective thermal management. However, the existing thermal models have limits to correctly predict the thermal behaviors, whose parameter extraction processes are normally complicated. Most of the thermal models generally omit the temperature effects, which greatly impairs their usefulness and effectiveness. Here, a temperature-dependent physical resistor–capacitor (RC) network model is proposed, which can accurately characterize the thermal behavior of SiC MOSFETs particularly under high-temperature conditions. Meanwhile, the boundary conditions are fully investigated and modeled, which guarantees the adaptation of the proposed model for different real-field applications. The proposed method can remarkably simplify the process of parameter extraction since only the steady-state temperature distribution information is required with the assistance of finite-element method (FEM). Finally, the effectiveness and the robustness of the proposed model are validated by FEM simulation and experiments. [ABSTRACT FROM AUTHOR]

Within the Central Andes of NW Argentina, the spatiotemporal distribution and style of deformation is strongly influenced by pre‐Cenozoic heterogeneities, mostly related to the Salta rift extension in the Cretaceous. At the enigmatic junction of the thin‐skinned Subandean belt and the thick‐skinned Santa Barbara System, the Tilcara Range and adjacent San Lucas block, located within the Eastern Cordillera, show thermochronological and field evidence of multiple exhumation events. Mesozoic (140‐115 Ma), pre‐Andean exhumation of basement highs is constrained by unconformities between basement and syn‐rift strata, as well as zircon (U‐Th‐Sm)/He cooling ages. Cenozoic Andean exhumation is quantified by apatite (U‐Th‐Sm)/He and fission track cooling ages, which were reset between the Late Cretaceous and Miocene. These data show that the westernmost Tilcara Range began exhuming in the late Oligocene‐early Miocene (26‐16 Ma), after which exhumation propagated to the border of the Eastern Cordillera in the middle Miocene (22‐10 Ma). The onset of rapid exhumation in the San Lucas block, which is located east of the Tilcara Range, occurred in the late Miocene (10‐8 Ma) in its western part, and in the late Miocene‐early Pliocene (6‐4 Ma) in its eastern part. Internal deformation of the San Lucas block, disturbing zircon (U‐Th‐Sm)/He and apatite fission track age patterns, predates propagation of rapid exhumation. The here presented low‐temperature thermochronology data set thus quantifies the multi‐phase exhumation history of the Eastern Cordillera of NW Argentina and constrains the timing of Andean propagation of exhumation within the Eastern Cordillera and the adjacent structural transition zone. Key Points: Zircon (U‐Th‐Sm)/He data suggests that pre‐Andean exhumation of Salta rift basement highs occurred in the Early Cretaceous (140‐115 Ma)Apatite (U‐Th‐Sm)/He and fission track data indicate a late Oligocene‐early Miocene (26‐16 Ma) onset of exhumation in the Tilcara RangeAndean exhumation overall propagated in‐sequence eastward, but thermal models indicate the possibility of local out‐of‐sequence movement [ABSTRACT FROM AUTHOR]

The architectural heritage of the 20th century is affected by several conservation problems in terms of material preservation, structural analysis, and reuse. Among these, material degradation and durability issues are the ones that have the most effect on the health state and, consequently, the survival of the constructions of the period. In order to conduct a proper analysis for preservation purposes, an interdisciplinary approach is necessary. The parabolic arch in Morano sul Po (Italy) is a reinforced concrete landmark in the Casale Monferrato area and is related to the industrial vocation of the territory, which is indissolubly linked to the cement production chain. The present paper reports the results of a non-destructive test campaign by a Politecnico di Torino multidisciplinary group, which combined acquisitions using different methods. The paper highlights the importance of a structured procedure to integrate different information coming from different techniques. The aim was to assess the health state of the structure and define the best procedures for building an information system based on the as-built modeling strategy, which could serve as the basis to provide conservation guidelines.

Metal Additive Manufacturing (AM) allows the fabrication of intricate shaped parts that cannot be produced with conventional manufacturing techniques. Despite the advantages of this novel manufacturing technology, the main drawback is the inferior fatigue performance of AM metal materials and parts due to the presence of process-induced defects that act as initial cracks. Reliable fatigue modeling methods that can assist the design and characterization of AM components must be developed. In this work, a computational damage-tolerance framework for the fatigue analysis of the AM metals and parts is presented. First, thermal modeling of the AM process for the part fabrication is performed to predict the susceptible areas for defect formation in the parts. From the processing of results, the characteristics of the critical defect are determined and used as input in a fracture mechanics-based model for the prediction of fatigue life of AM metals and parts. For validation purposes, the framework is utilized for the fatigue modeling and analysis of AM Ti-6Al-4V and 316L SS metals of relative experimental test cases found in the literature. The predicted results exhibit good correlation with the available experimental data, demonstrating the predictive capability of the modeling procedure.

In hot climates, PV efficiency drops dramatically if the surface temperature of the panels rises over a specific limit. Consequently, a cooling system is required to preserve PV modules as close to their operating temperature as feasible. For this purpose, the influence of an increase in PV surface temperature on PV performance was studied experimentally and numerically at the Research Institute of Petroleum Industry (RIPI) in July. The current study uses a cooling system consisting of rows of copper pipes connected to the PV backside. The experiments are conducted for four distinct scenarios, each with a different input fluid temperature ranging from 19.5 to 61 °C. The parametric analysis focuses on three influential factors: ambient temperature, solar radiation, and fluid inlet temperatures. In addition, other inputs are configured in accordance with the experimental conditions. The results showed that installing a cooling water system decreased the PV surface temperature from 60.20 °C to 40.24 °C at 9:00 am and from 73.98 °C to 73.33 °C at 1:30 pm. Furthermore, the electrical, thermal, overall, and exergy efficiencies drop as radiation intensity and water inlet temperature increase. In addition, the numerical results are validated with the experimental ones, and it shows high degrees of concordance.

Arctic regions are highly impacted by the global temperature rising and its consequences and influences on the thermo-hydro processes and their feedbacks. Theses processes are especially not very well understood in the context of river–permafrost interactions and permafrost degradation. This paper focuses on the thermal characterization of a river–valley system in a continuous permafrost area (Syrdakh, Yakutia, Eastern Siberia) that is subject to intense thawing, with major consequences on water resources and quality. We investigated this Yakutian area through two transects crossing the river using classical tools such as in–situ temperature measurements, direct active layer thickness estimations, unscrewed aerial vehicle (UAV) imagery, heat transfer numerical experiments, Ground-Penetrating Radar (GPR), and Electrical Resistivity Tomography (ERT). Of these two transects, one was closely investigated with a long-term temperature time series from 2012 to 2018, while both of them were surveyed by geophysical and UAV data acquisition in 2017 and 2018. Thermodynamical numerical simulations were run based on the long-term temperature series and are in agreement with river thermal influence on permafrost and active layer extensions retrieved from GPR and ERT profiles. An electrical resistivity-temperature relationship highlights the predominant role of water in such a complicated system and paves the way to coupled thermo-hydro-geophysical modeling for understanding permafrost–river system evolution.

Lunar collapse pits may provide access to subsurface lava tubes of unknown extent. We present Diviner Lunar Radiometer measurements showing that the Mare Tranquillitatis and Mare Ingenii pits exhibit elevated thermal emission during the night, ∼100 K warmer than the surrounding surface. Using these data, along with computational thermophysical models, we characterize the thermal environment inside pits and potential caves. Near the equator, peak day‐time temperatures on regolith‐covered pit floors can potentially reach >420 K, whereas temperatures beyond the opening in permanent shadow would maintain a nearly constant temperature of ∼290 K, similar to that of a blackbody cavity in radiative equilibrium. Thermal IR measurements such as those of Diviner can readily detect pit thermal signatures but would be insensitive to the existence of caves they may host, as the latter would only induce a 0.1 K increase to night‐time temperatures of the overlying surface. Plain Language Summary: Since the discovery of pits on the Moon by JAXA's SELENE spacecraft in 2009, there has been interest in whether they provide access to caves that could be explored by rovers and astronauts. These features are likely created by the ceiling of a lava tube (or more generally, cave) collapsing. Using data from the Diviner instrument aboard the Lunar Reconnaissance Orbiter, which has been continuously measuring the temperature of the lunar surface for over 11 years, we thoroughly characterized the environment of one prominent pit. Located in Mare Tranquillitatis, the pit's thermal environment is more hospitable compared to anywhere else on the Moon, with temperatures varying minimally around a comfortable 17°C (or 63° F) wherever the Sun does not shine directly. If a cave extends from a pit such as this, it too would maintain this comfortable temperature throughout its length, varying by less than 1°C over an entire lunar day. Although we cannot be completely certain of a cave's existence through remote observations, such features would open the door for future exploration and habitation on the Moon: they could provide shelter from dramatic temperature variations present elsewhere on the lunar surface. Key Points: Lunar pits stay warmer than the surface during the night, with the floor maintaining temperatures >230 K according to computational modelsCaves stemming from lunar pits would behave like blackbody cavities at ∼290 K and have nearly invariable temperatures far from the openingLunar caves would provide a temperate, stable, and safe thermal environment for long term exploration and habitation of the Moon [ABSTRACT FROM AUTHOR]

Friction stud welding process is a suitable candidate in joining stud fasteners for steel structure buildings, military vehicles, automobiles, aircraft, ocean liners, bridges, ship buildings, etc., The peak temperature for welding is achieved by converting mechanical energy to thermal energy at the sample interface without the use of electric energy from other sources because it is a solid-state process. The study of the thermal behavior of different metals during friction stud welding is very important since it is a thermal energy process. However, there is no good thermal model for the friction stud welding process. In this work, the generation of heat flux at the interfacial area of two distinct metals, namely aluminum and mild steel, is calculated using a mathematical model. The temperature at the interfacial region, which plays a significant role in the quality and strength of the weld component, is particularly focused on experimentation and analytical modeling. In the experimentation, a noncontact type infrared thermometer is used to measure temperature directly. The temperature profile was determined by the finite difference method based on thermal resistance and capacitance formulation at transient conditions. The obtained mathematical results are compared with the experimental results at the distance of 5 and 10 mm from the welded interface. The computed temperature profile is in good agreement with the experimental data on the heating side and with a minimum degree of deviation in the cooling part. The maximum percentage of error for the 5 mm interface is 3.349 and for the 10 mm interface is 2.857. This deviation is due to the zero-axial shortening assumption in the analytical model. Besides, the temperature characteristics of the welded are analyzed at various time increments by numerical simulation. As a result, the predicted temperature is more on the aluminum side compared to the mild steel due to a change in thermal properties. This proposed thermal model would be helpful to improve the design and manufacture of welding machines. [ABSTRACT FROM AUTHOR]

As the dynamic random access memory (DRAM) chip tends to the larger storage capacity by die stacking, the 3D die stacking requires thermal modeling for fast temperature predicting and initial design. This work presents a theoretical model capable of fast calculating and optimizing the temperature of each die. The improved thermal network defines equivalent shape correction parameters to improve the calculation accuracy of the thermal network. The 3D die sacking derives a novel topology of improved thermal network through the division of the heat transfer path inside DRAM. The analysis demonstrates that the calculating results of improved thermal network show good consistency with the finite element method in steady and transient states thermal analysis. Beyond this, the effect of size and thermal power is discussed in the calculation accuracy. The improved thermal network is used in the optimization design of DRAM with eight-dies vertical stacking. The maximum temperature increment is reduced by 15% after optimization. • The improved thermal network of DRAM considers all heat transfer paths in the 3D die stacking. • The shape correction parameters are defined to improve the calculation accuracy of the improved thermal network. • The effects of size and thermal power on the calculation accuracy of the improved thermal network are analyzed. • The model effectiveness is verified by an optimization design of DRAM with eight-die stacking. [ABSTRACT FROM AUTHOR]

This paper has the objective to present equations capable of generating one-dimensional models that permit to quantify the thermal influence caused by igneous intrusions. In Paraná Basin, the petroleum systems were great influenced by igneous activities in which they are presented by a thick lava effusion, large number of dykes in the entire sedimentary section and various levels of sills intruded in stratifications to provide thermal energy for organic maturation. Thus, a better understanding of how and how much the intrusions affect the generation of oil and gas is extremely necessary since the knowledge related to the effects of intrusions in such atypical petroleum system is still insufficient. The obtained results show: the thermal influence caused by igneous intrusions is much higher than that proposed in the literature; the greater the number of intrusions and the thicker they are, the thermal influence is unfavorable at short distances and favorable at large distances. [ABSTRACT FROM AUTHOR]

Definition: A thermal bridge is a component of a building that is characterized by a higher thermal loss compared with its surroundings. Their accurate modeling is a key step in energy performance analysis due to the increased awareness of the importance of sustainable design. Thermal modeling in architecture and engineering is often not carried out volumetrically, thereby sacrificing accuracy for complex geometries, whereas numerical textbooks often give the finite element method in much higher generality than required, or only treat the case of uniform materials. Despite thermal modeling traditionally belonging exclusively to the engineer's toolbox, computational and parametric design can often benefit from understanding the key steps of finite element thermal modeling, in order to inform a real-time design feedback loop. In this entry, these gaps are filled and the reader is introduced to all relevant physical and computational notions and methods necessary to understand and compute the stationary energy dissipation and thermal conductance of thermal bridges composed of materials in complex geometries. The overview is a self-contained and coherent expository, and both physically and mathematically as correct as possible, but intuitive and accessible to all audiences. Details for a typical example of an insulated I-beam thermal bridge are provided. [ABSTRACT FROM AUTHOR]

Chiplet-based packaging technology integrates multiple heterogeneous dies with different functions and materials into a single system as a LEGO-based approach using advanced packaging technology. However, it also brings new challenges in the thermal design aspect and thermal crosstalk between chiplets. In this article, the thermal modeling of a chiplet-based packaging with a 2.5-D interposer was carried out. Two chiplets were mounted on the interposer side-by-side. A Cu lid was attached to the top surfaces of the chiplets and periphery of the interposer through the thermal interface material1 (TIM1) and adhesive, respectively. To further dissipate the heat from the top side, a heat sink was attached to the top surface of the lid through a layer of TIM2. The effects of the TIM type, bonding approach between chiplets and interposer, heat sink structure, thermal crosstalk, convective heat transfer coefficient above the lid, and thermal design power (TDP) were analyzed. The study results show that the bumpless interconnect is beneficial for the heat dissipation of the chiplet-based packaging. The staggered column fin can exhibit superior cooling performance. The short pitch would bring cooling challenges for fine-pitch multiple chiplets integration. The temperature is decreased rapidly first and then slowed down with the increase of convective heat transfer coefficient above the lid. Under 10 000 W/ $\text{m}^{2}\cdot \text{K}$ , the maximum TDP was about 250 W. [ABSTRACT FROM AUTHOR]

In this article, we present a novel approach to real-time tracking of full-chip heatmaps for commercial off-the-shelf microprocessors based on machine-learning. The proposed post-silicon approach, named RealMaps, only uses the existing embedded temperature sensors and workload-independent utilization information, which are available in real-time. Moreover, RealMaps does not require any knowledge of the proprietary design details or manufacturing process-specific information of the chip. Consequently, the methods presented in this work can be implemented by either the original chip manufacturer or a third party alike, and is aimed at supplementing, rather than substituting, the temperature data sensed from the existing embedded sensors. The new approach starts with offline acquisition of accurate spatial and temporal heatmaps using an infrared thermal imaging setup while nominal working conditions are maintained on the chip. To build the dynamic thermal model, a temporal-aware long-short-term-memory (LSTM) neutral network is trained with system-level features such as chip frequency, instruction counts, and other high-level performance metrics as inputs. Instead of a pixel-wise heatmap estimation, we perform 2D spatial discrete cosine transformation (DCT) on the heatmaps so that they can be expressed with just a few dominant DCT coefficients. This allows for the model to be built to estimate just the dominant spatial features of the 2D heatmaps, rather than the entire heatmap images, making it significantly more efficient. Experimental results from two commercial chips show that RealMapscan estimate the full-chip heatmaps with 0.9 $^{\circ }$ ∘ C and 1.2 $^{\circ }$ ∘ C root-mean-square-error respectively and take only 0.4ms for each inference which suits well for real-time use. Compared to the state of the art pre-silicon approach, RealMaps shows similar accuracy, but with much less computational cost. [ABSTRACT FROM AUTHOR]

Knowledge of temperature distribution in power transformers is essential for the management of electrical distribution systems. Monitoring the hot-spot temperature of a power transformer can extend its lifetime. This paper introduces two novel models called Modified Set-Membership evolving multivariable Gaussian (MSM-eMG) and variable step-size evolving multivariable Gaussian (VS-eMG) for time series forecasting. Both approaches are an enhanced version of the evolving multivariable Gaussian model that use adaptive filtering to update the learning rate parameter, which updates the centers of the clusters, aiming to achieve better performance of the models. To evaluate their performance were used two data sets from a real power transformer; the first data set of the transformer has no overload conditions, and the second one has it. A synthetic data set was also used, as a benchmark, in order to show the effectiveness of these models in different scenarios. The obtained results are compared with the performance of the original evolving multivariable Gaussian and with other classical evolving and non-evolving models suggested in the literature. Both proposed models obtained the lowest errors in all simulations and presented a competitive number of rules in the real data, suggesting these models are flexible and efficient approaches to forecast complex data with high accuracy. [ABSTRACT FROM AUTHOR]

The production of biogas by means of the anaerobic digestion process is becoming increasingly attractive in the green economy context. When municipal organic waste is used to produce biogas, a further positive effect on urban waste disposal is obtained. Starting from the anaerobic digestion model n.1, an accurate analysis of the temperature effects on the anaerobic digestion process in a plug flow reactor is performed. This paper aims at presenting a comprehensive and integrated one-dimensional biological and thermal model for a plug flow reactor. Partial differential equations with respect to time and space are considered to model the heat transfer between the reactor and the internal heat exchanger and between the reactor and the environment. In this scope, a suitable simulation code was developed in MATLAB and validated using the data available in literature. The results of the calculations show that temperature plays a crucial role in the anaerobic digestion process, since it strongly affects the kinetic rates of the microbial species and the methane production. The results obtained in terms of temperature fields and biogas production are compared with the ones available in literature, dealing with a continuously stirred tank reactor. The comparison is conducted considering that both reactors process a volumetric waste flow rate of 20   m 3 / d and have the same structural characteristics. The plug flow reactor resulted better performance with a produced biogas flow rate equal to 2300   N m 3 /year. [ABSTRACT FROM AUTHOR]

Water stress particularly affects developing regions. It is necessary to develop low-cost and small-scale solutions that do not require advanced technology and abundant energy resources to produce fresh water. A viable solution for rural coastal areas is seawater desalination using the solar still — a device that only relies on solar radiation to operate. The present work focuses on improving the solar still water yield. To achieve this objective, an alternative thermal model, which compromises a coupled energy balance for each solar still component, was proposed. This model increases the simulation accuracy for different designs, locations, and ambient conditions, predicting the water yield with a maximum deviation of 6% for the evaluated experiments. In addition, for a selected experiment, a parametric analysis was performed and, it was concluded that the potential parameters to enhance the water yield are: water depth, structure design, insulation, incident solar radiation, and basin-glass temperature difference. Based on the parametric study and the identified improvement solutions from the literature, feasible options were studied, such as: implementing reflectors, solar still design modification, increasing inner convection (insignificant improvement), using a porous medium (relevant for large water depths in the solar still) and separating evaporation/condensation (largely conditioned by ambient conditions). • Alternative thermal model with a 6% maximum deviation for the evaluated experiments. • Design optimization and adding reflectors enhance the water yield the most. • Cooling and convection enhancement systems present negligible water yield increase. • Porous medium is an interesting solution for solar stills with large water quantities. • Separating evap/condensation is suitable for specific designs and ambient conditions. [ABSTRACT FROM AUTHOR]

There are certain advantages in applying an airlift photobioreactor (PBR) intended for microalgae culture to a building façade, such as making use of the solar illuminated surfaces and the possibility of chemical recycling through photosynthetic growth (utilizing the carbon dioxide emissions from boiler combustion, for example). This study concerns the development of a thermal model for integral building-façade photobioreactors which can predict dynamic changes in the temperature of the culture medium in response to changes in meteorological conditions, taking into account the thermal interchange with the host building. The proposed model was experimentally validated with data obtained in outdoor conditions, using a pilot-scale system (SymBiO 2 -Box) located in Saint-Nazaire (France), and subsequently used to set up numerical simulations and optimization studies to develop control strategies for efficient thermal regulation of the PBR with optimal energy consumption. The advantage of using an active passageway between the façade and PBRs was investigated in particular. [Display omitted] • A thermal biofaçade model was developed and validated over 5 months' operation. • A sensitivity analysis revealed the main parameters influencing thermal behavior. • Various temperature regulation pre-set and biofaçade configurations were tested. • A thermal symbiosis between the PBR and the host building proved efficient for temperature regulation. • The introduction of an active passageway enabled significant energy savings. [ABSTRACT FROM AUTHOR]

This article concerns the indirect thermographic temperature measurement of a die of the semiconductor diode D00-250-10. The article shows how the goal was achieved. The methodology of selecting the point at which thermographic measurements of the temperature of the diode cases were performed is discussed. The method of thermographic measurement of the case temperature and the measuring system used is described. The method of simulations making it possible to obtain the die's temperature on the basis of thermographic casing temperature measurement is presented. In order to enable a better understanding of the discussed issues, the construction of the diode used and the heat flow equation are described. As a result of the work carried out, the point at which the temperature is closest to the die temperature was indicated on the diode case. It is shown that the difference between the casing temperature and the die temperature does not exceed 2 °C at the point indicated. An indirect measurement of the die's temperature is carried out for different values of the power dissipated on the die. [ABSTRACT FROM AUTHOR]

The prediction of the maximum operating temperature in electric machines is very important to ensure that the machine can produce the required power safely. Accurate thermal modeling is required to predict the heat transfer coefficient (HTC) of walls between coolant and heat sources and estimate the temperature in the machine. Analytical calculation of HTC is difficult for sophisticated geometric bodies since the dimensionless correlations are only available for simple geometries. To reduce the effort required to develop a thermal model of the cooling system of an electric machine, a two-way hybrid multiphysics approach using finite-element analysis (FEA) and computational fluid dynamics (CFD) to determine the HTC and evaluate the thermal performance of a liquid-cooled electric machine is presented in this article. In this study, a 60-kW switched reluctance machine (SRM) is used as an example model to evaluate its thermal performance. In the hybrid multiphysics approach, using the HTC estimated by CFD and heat generation in the machine as the inputs, the FEA is used to determine the maximum steady-state temperature in the machine. An analytical approach is also implemented to determine the HTC of the example SRM to correlate with the HTC obtained using a hybrid approach. The analytical HTC is used in FEA to obtain the temperature distribution in the machine. The temperature obtained from hybrid and analytical approaches is compared. The SRM considered in this study is built and tested for different operating points. The machine is tested for a long time to record the steady-state temperature at different operating points. Results obtained from the hybrid approach are validated with the experimental temperature data. [ABSTRACT FROM AUTHOR]

Abstract In Sub-Saharan countries, cooking is usually done at a domestic scale using rudimentary stoves with wood or charcoal as combustibles. To improve the cooking behavior and reduce the deforestation, an improved pellet cookstove was conceptualized with guiding ideas in mind such as simplicity, robustness and ability to burn pellets built with local wood residues under a natural draught. Combustion and water ebullition tests were performed with two configurations of the upper part of the cookstove: thick steel plate or ring, and with standardized EN+ pellets as combustible. The main pollutant gases (CO, CO2 and NOx), together with O2, were continuously measured at different positions of the cookstove during a water ebullition test with the ring configuration. The levels measured above the pot were lower than the thresholds currently proposed by the World Health Organization. Simple and phenomenological thermal models were proposed to simulate the plate, or ring, and water temperatures during the combustion or water ebullition tests and to determine the intrinsic convection coefficients. The maximal relative differences between the experimental and simulated temperatures were computed between 7 and 21%. The stove power was evaluated at 4336 ± 23 W. The cookstove yield for the water ebullition test with the ring configuration was computed equal to 12.3 ± 0.1%, slightly lower than that of cookstoves previously analyzed in the literature.

The present study investigated the geochemical characteristics of Shemshak shales as a probable oil source rock in the Gushfil mine located in the Sanandaj-Sirjan Zone (SSZ), Iran. Trace elements such as nickel, vanadium, chrome, molybdenum, and cobalt are used as paleoenvironmental indicators. Moreover, the ratio of these elements shows that oxic to disoxic conditions prevailed during the sedimentation period. The interrelation of these elements indicates that the upper part of Shemshak Formation of the Jurassic age was deposited in a terrestrial to the marine-terrestrial influenced environment. The solid bitumen reflectance (BR) documents that the black shales presently are overmature. Conjugation of BR and the insolubility of organic matter in carbon disulfide illustrates the presence of pyrobitumen and its subgroup epi- to meso-impsonite, which is also characterized by the absence of any fluorescence under ultraviolet light. The ratio of light to heavy hydrocarbons proves that the type of solid bitumen before pyro-bituminization has been a primary-oil solid bitumen, which could migrate through fractures and coarse pores. The primary-oil solid bitumen might be derived from Kerogen types II and III as documented by fibrous plant fragments, translucent phytoclasts and pollens. Presently, due to intense degradation, kerogen type IV dominates. The modeling confirms that a thermal degradation had probably occurred after the deposition of Lower Cretaceous carbonates when the shales were able to produce bitumen. Ultimately, intense hydrothermal degradation led the solid bitumen to evolve into pyrobitumen and caused the shales to evolve into a dry gas window.

Laser micromachining can serve as a coarse machining step during sample preparation for high-resolution characterization methods leading to swift sample preparation. However, selecting the right laser parameters is crucial to minimize the heat-affected zone, which can potentially compromise the microstructure of the specimen. This study focuses on evaluating the size of heat-affected zone in laser annular milling, aiming to ascertain a minimal scan diameter that safeguards the inner region of micropillars against thermal damage. A computational model based on the finite element method was utilized to simulate the laser heating process. To validate the simulation results, a picosecond pulsed laser is then used to machine the micropillars of Al and Si. The laser-machined samples were subjected to surface and microstructural analysis using Scanning Electron Microscope (SEM) and Electron Backscatter Diffraction (EBSD) scans. The length of heat affected zone obtained from simulations was approximately 6 μ m for silicon and 12 μ m for aluminum. The diameter of micropillars formed with laser machining was 10 μ m for silicon 26 μ m for aluminum. The core of the pillars was preserved with less than one degree of microstructural misorientations making it suitable for further processing for preparing specimens for techniques like APT and TEM. For silicon micropillars, the preserved central region has a diameter of 6 μ m and for aluminum its around 20–24 μ m. Additionally, the study determines the minimum scan diameter that can be achieved using the given laser machining setup across a range of common materials. • Determined minimum scan diameters for laser machining of micropillars with preserved core • Thermal damage during laser micromachining was modeled using finite element method • Si micropillars of diameter 10 μ m with a preserved core produced with laser machining • The modeling approach was extended to a range of engineering materials. [ABSTRACT FROM AUTHOR]

Air–water heat transfer is a crucial method for achieving stable air supply in cleanrooms. This paper models the heat transfer process in the specific scenarios, enabling estimation of the heat exchangers' outlet temperature response based on variations in the inlet temperature. Additionally, considering practical requirements, we derive the outlet performance in scenarios involving multiple heat exchangers in series. An experimental setup was established to evaluate the time-domain and frequency-domain responses of the heat exchanger outlet airflow under different flow rates and numbers of heat exchangers. The spectral distribution fits of the outlet air consistently exceeded 82%. Furthermore, precise estimation error at the m ° C level was achieved, with the average error ratio of the outlet air approaching 10%. The experimental results validated the model's accuracy and provided guidance for achieving high-precision air supply, particularly in maintaining a temperature-stable output airflow through constant-temperature water and air–water heat exchange processes. • Developing the air–water cross-flow heat transfer process model. • Deriving the output performance under series heat exchangers. • Achieving accurate heat exchanger outlet temperature estimates. • Reference for realizing high-precision supply air temperature in cleanrooms. [ABSTRACT FROM AUTHOR]

Abstract Alaska’s North Slope is predicted to experience twice the warming expected globally. When summers are longer and winters are shortened, ground surface conditions in the Arctic are expected to change considerably. This is significant for Arctic Alaska, a region that supports surface infrastructure such as energy extraction and transport assets (pipelines), buildings, roadways, and bridges. Climatic change at the ground surface has been shown to impact soil layers beneath through the harmonic fluctuation of the active layer, and warmer air temperature can result in progressive permafrost thaw, leading to a deeper active layer. This study attempts to assess climate change based on the climate model data from the fifth phase of the Coupled Model Intercomparison Project and its impact on a permafrost environment in Northern Alaska. The predicted air temperature data are analyzed to evaluate how the freezing and thawing indices will change due to climate warming. A thermal model was developed that incorporated a ground surface condition defined by either undisturbed intact tundra or a gravel fill surface and applied climate model predicted air temperatures. Results indicate similar fluctuation in active layer thickness and values that fall within the range of minimum and maximum readings for the last quarter-century. It is found that the active layer thickness increases, with the amount depending on climate model predictions and ground surface conditions. These variations in active layer thickness are then analyzed by considering the near-surface frozen soil ice content. Analysis of results indicates that thaw strain is most significant in the near-surface layers, indicating that settlement would be concurrent with annual thaw penetration. Moreover, ice content is a major factor in the settlement prediction. This assessment methodology, after improvement, and the results can help enhance the resilience of the existing and future new infrastructure in a changing Arctic environment.