Heating Patterns Research Articles

Computational design and fabrication of active 3D-printed multi-state structures for shape morphing

Active structures can change their shape, properties, and functionality as a response to changing operational conditions, which makes them more versatile than their static counterparts. However, most active structures currently lack the capability to achieve multiple, different target states with a single input actuation or require a tedious material programming step. In this work, a computational design and fabrication framework is proposed to generate structures with multiple target states for one input actuation that do not require a separate training step. A material dithering scheme based on multi-material 3D printing is combined with locally applied copper coil heating elements and sequential heating patterns to control the thermo-mechanical properties of the structures and switch between the different deformation modes. A novel topology optimization approach based on power diagrams is used to encode different target states in the structure while ensuring the fabricability of the structures. The numerical and experimental results show that the optimization framework can produce structures that show the desired motion, but experimental accuracy is limited by current fabrication methods. The generality of the proposed method makes it suitable for the development of structures for applications in many different fields from aerospace to robotics to animated fabrication in computer graphics.

Impacts of Extreme Temperature and Precipitation on Crops during the Growing Season in South Asia

South Asia, one of the most important food producing regions in the world, is facing a significant threat to food grain production under the influence of extreme high temperatures. Furthermore, the probability of simultaneous trends in extreme precipitation patterns and extreme heat conditions, which can have compounding effects on crops, is a likelihood in South Asia. In this study, we found complex relationships between extreme heat and precipitation patterns, as well as compound effects on major crops (rice and wheat) in South Asia. We also employed event coincidence analysis (ECA) to quantify the likelihood of simultaneous temperature and crop extremes. We used the Enhanced Vegetation Index (EVI) as the primary data to evaluate the distinct responses of major crops to weather extremes. Our results suggest that while the probability of simultaneous extreme events is small, most regions of South Asia (more than half) have experienced extreme events. The regulatory effect of precipitation on heat stress is very unevenly distributed in South Asia. The harm caused by a wet year at high temperature is far greater than that during a dry year, although the probability of a dry year is greater than that of a wet year. For the growing seasons, the highest significant event coincidence rates at a low EVI were found for both high- and low-temperature extremes. The regions that responded positively to EVI at extreme temperatures were mainly concentrated in irrigated farmland, and the regions that responded negatively to EVI at extreme temperatures were mostly in the mountains and other high-altitude regions. Implications can guide crop adaptation interventions in response to these climate influences.

Effects of electropulsing treatment on the microstructural evolution of hot-rolled TiBw/TA15 composite billet with a network architecture

The use of resistance heating patterns is one of the underlying opportunities for the hot processing of hard-working materials. Here, the effect of electropulsing treatment (EPT) on the microstructure of a hot-rolled TiBw/TA15 composite billet with a network architecture was investigated. Experimental results showed that the stable temperature platform presented a competition between Joule heat and heat dissipation, including heat conduction, convection, and radiation, and the temperature distribution was non-uniform. The ultimate temperatures of the EPT samples increased gradually as the electropulsing increased. Then, the traditional heat treatment sample was compared with the EPT samples via electron backscatter diffraction, scanning electron microscopy, and X-ray diffraction. Results of analyses indicate that the athermal effect independent from electropulsing can promote the growth of grains, but it also decreases the dislocation density and increases the recrystallization fraction. Therefore, athermal effects can exist authentically in contrast to the thermal effects, and specific thermal effects can hardly achieve the results obtained in this study.

MWA Performed at 5.8 GHz through ‘Side Firing’ Approach: An Exploratory Study

Recent studies have shown that ablation techniques have the potential to eradicate adrenal adenomas while preserving the functionalities of the adrenal gland and the surrounding anatomical structures. This study explores a new microwave ablation (MWA) approach operating at 5.8 GHz and using anatomical and dielectric characteristics of the target tissue to create directional heating patterns. Numerical simulations are executed in planar and 3D adrenal models, considering two energy doses. The numerical study is refined accounting for the vaporization of the tissue water content. Ex vivo experimental evaluations on porcine adrenal models complete the study. The numerical and experimental results show that spherical ablation zones are able to cover the target for both energy doses considered. Nonetheless, most of the non-targeted tissues can be preserved from excessive heating when low energy level is used. Numerical models accounting for water vaporization are capable to foresee the experimental temperature values. This study shows that the proposed MWA directional approach operating at 5.8 GHz can be considered for creating effective and selective ablation zones.

Extraction of natural piperine crystals from black pepper with expanded graphite for thermal energy storage

Substantial research was done on the synthesis of piperine crystals (PC) from black pepper using expanding graphite (EG) as a promising organic phase change material (O-PCM). Researchers examined the chemical structure and thermal properties of the substance. Using the diffusion–exudation circle method, the PC/EG-blended PCM had the highest PC mass content, at 93.4 %. According to (DSC) study, the melting and crystallization temperatures are 135.6 °C and 117.4 °C, and their related latent energies are 283.14 KJ/kg and 192.45 KJ/kg. This finding implies that the material retains a respectable capacity for heat storage after being exposed to multiple heat patterns. Thermal storage/discharge studies revealed that the EG/PC material had much better heat storage/discharge ratios than the PC sample. At ambient circumstances, our findings indicated that the Herbal Piperine crystals/expandable graphite PCM was a superior thermal energy storage medium. The results demonstrated that the proposed hybrid composite can be considered as a potential solar energy storage material for a variety of applications, including thermal cooling of photovoltaic panels, automobiles, digital units, solar residential heating systems, and passive solar heating systems.

Effects of Container Design on the Temperature and Moisture Content Distribution in Pork Patties during Microwave Heating: Experiment and Numerical Simulation

Effects of the container design on the heat transfer rate and food quality during microwave heating were explored and validated with numerical simulations and experiments. The uniformity of moisture content and temperature was investigated, and to describe microwave heating patterns, a simulation model was created. Pork patties with different moisture and salt contents were heated in three different containers (center and edge-perforated lid as well as without lid) to achieve 80 °C using a domestic microwave oven. Compared to the center or mid-way positions, the temperatures at the edge of the patties rose quickly. By containing the evaporated vapor from the heated pork patties inside the container, the container with a center-perforated lid decreased the heating rate and non-uniformity in temperature and moisture content. A simplified numerical model for the electromagnetics, heat, and momentum transfer coupling simulation was developed to understand the moisture and temperature distribution of the pork patties after microwave heating. Heating uniformity and the final quality of the pork patties could be improved by a container with a center-perforated lid. The proposed model was able to describe the microwave warming process for ready-to-eat products; thus, it is a useful tool for designing microwavable ready meals.

Development of a metamaterial‐based compact applicator for hyperthermia

AbstractA compact focused metamaterial‐based applicator is investigated for hyperthermia cancer treatment in this letter. The metamaterial‐based applicator consists of a double spiral antenna (DSA), an artificial magnetic conductor (AMC) as a reflector, and a frequency selective surface (FSS) as a lens. An AMC structure (64 × 64 mm2) is placed in the back of the antenna at a 5 mm distance that converges the bidirectional field pattern of the antenna into the directional field pattern. Further, to increase penetration inside the tissue, an FSS structure (64 × 64 mm2) is placed at the top of DSA at a distance of 4 mm. The FSS directs the energy toward the tumor location and provides a uniform heating pattern. The field and temperature distribution are numerically obtained for the proposed applicator in the heterogeneous phantom (layers of skin, fat, and muscles), and the performance of the applicator is evaluated in terms of the specific absorption rate, penetration depth, and effective field size. The performance of the applicator is also analyzed for a deeply placed (at 16 mm from the skin surface) irregular‐shaped tumor. The temperature profile calculates 44°C at an input power of 2.5 W. The results show that the applicator is capable of heating sufficiently deep‐seated tumors.

Dynamic integrated control for Chinese district heating system to balance the heat supply and heat demand

District heating system (DHS) mainly consumes fossil fuel in North China. Reducing energy consumption of DHS is conducive to low-carbon sustainable development. Poor matching of heat supply and heat demand limits the efficient operation of the district heating system. To solve this issue, a dynamic integrated control method of buildings and heat exchange station (HES) is proposed. On the building side, five heating patterns are designed for space heating of buildings based on their indoor demand temperatures. On the HES side, to produce the accurate heat supply, four correction factors are introduced to modify the temperature-flow equations based on the DHS configuration difference between actual operation and design conditions. Five total correction factors are integrated to determine eventual regulation equations. Then single-level and double-level reverse control strategies are presented. A case study is illustrated to validate the proposed approach. With the integrated control, the matching values of calculated heat supply and actual heat consumption were 85.46%∼96.90% of buildings and over 90% of the whole DHS. Four years of operation data indicated the 12.75%∼31.08% of heat-saving rate and 5.23%∼24.62% of electricity saving rate, which brings about total emission reductions of 3803 tons CO2, 35 tons SO2 and 10 tons NOx.

Development of Vacuum-Steam Combination Heating System for Pasteurization of Sprout Barley Powder

The processing of sprout vegetables in powder form has been known to extend the shelf-life by retaining nutritional values; however, sprout powder products were exposed to a variety of contaminants, such as microbial contaminants, during processing and storage. Therefore, the proper treatment for removing the contaminants in the powder was required without compromising their quality properties. This study was conducted (1) to determine a suitable pasteurization method for sprout barley powder, and (2) to investigate the effect of vacuum-steam heating combination treatment on the quality change and the lethality of microorganisms in sprout barley powder. The heating pattern of sprout barley powder was elucidated with a vacuum-thermal combination system consisting of a vacuum chamber, overhead stirrer, far-infrared heater, and PID (Proportional-Integral-Differential) controller. In addition, the mixing patterns of sprout barley powder, depending on the types of stirring blades, were evaluated by discrete element modeling using EDEM™ software. The vacuum-steam combination heating system was fabricated using the investigated pre-design factors. The quality change in sprout barely powder was evaluated by measuring the microbial inactivation, CIE values (L*, a*, b*, ΔE), and water activity (aw). During the pasteurization process, steam could be directly injected into the chamber at regular intervals for two hours to transfer moisture and heat to the powder. By combining steam and vacuum conditions, the population of E. coli O157:H7 in the powder was reduced by 4.33 log CFU/g, eliminating all E. coli O157:H7 in the powder. In addition, the water activity (aw) of the powder was significantly decreased in a vacuum pressure environment without the quality deterioration.

Radio Frequency Drying Behavior in Porous Media: A Case Study of Potato Cube with Computer Modeling

To study the mechanism of heat and mass transfer in porous food material and explore its coupling effect in radio frequency (RF) drying processes, experiments were conducted with potato cubes subjected to RF drying. COMSOL Multiphysics® package was used to establish a numerical model to simulate the heat and mass transfer process in the potato cube and solved with finite element method. Temperature history at the sample center and the heating pattern after drying was validated with experiment in a 27.12 MHz RF heating system. Results showed the simulation results were in agreement with experiments. Furthermore, the temperature distribution and water vapor concentration distribution were correspondent with water distribution in the sample after RF drying. The water concentration within the food volume was non-uniform with a higher water concentration than the corner, the maximum difference of which was 0.03 g·cm−3. The distribution of water vapor concentration in the sample was similar to that of water content distribution since a pressure gradient from center to corner allowed the mass transfer from the sample to the surrounding in the drying process. In general, the moisture distribution in the sample affected the temperature and water vapor concentration distribution since the dielectric properties of the sample were mainly dependent on its moisture content during a drying process. This study reveals the mechanism of RF drying of porous media and provides an effective approach for analyzing and optimizing the RF drying process.

Double diffusion thermal exploration of Cross nanomaterial due to moving surface with sinusoidal waves: Cattaneo–Christov model

The nanoparticles convey noteworthy applications in many engineering and industrial systems like cooling and heat processes, thermal extrusion systems, heat exchangers, as an energy source, treatment of various diseases and chemotherapy. Owing to such importance of nanomaterials, various studies are presented for nanofluids with diverse flow features. This investigation discloses an unsteady flow of Cross nanofluid over periodically accelerated imbedded in porous space. The combined heat and mass transportation aspects of nanomaterials are entertained with applications of Buongiorno’s model. Further, Cattaneo–Christov fluxes are mathematically implemented for investigating the diffusion aspect of heating and mass pattern. Additionally, the nonlinear on set of radiative distribution is followed. Referred to the suitable transformations, the independent variable in the governing system is reduced. The homotopy-based analytical expressions are obtained for set of flow parameters. The complete graphical exploration is visualized, for governing parameters, and scrutinized. The mass and heat transfer pattern has been inspected in the form of numerical data. It is perceived that velocity profile has decreasing tendency for enhancement in Weissenberg number and magneto-porous constant. The temperature and concentration profiles diminish with increase of thermal and solutal relaxation constants, respectively.

Ocean dynamics and tracer transport over the south pole geysers of Enceladus

ABSTRACT Over the south pole of Enceladus, an icy moon of Saturn, geysers eject water into space in a striped pattern, making Enceladus one of the most attractive destinations in the search for extraterrestrial life. We explore the ocean dynamics and tracer/heat transport associated with geysers as a function of the assumed salinity of the ocean and various core-shell heat partitions and bottom heating patterns. We find that, even if heating is concentrated into a narrow band on the seafloor directly beneath the south pole, the warm fluid becomes quickly mixed with its surroundings due to baroclinic instability. The warming signal beneath the ice is diffuse and insufficient to prevent the geyser from freezing over. Instead, if heating is assumed to be local to the geyser (either generated in the ice due to tidal dissipation or friction or generated in the ocean as water flushes in/out of the geyser slot under tidal forcing), geyser can be sustained. In this case, the upper ocean beneath the ice becomes stably stratified creating a barrier to vertical communication, leading to transit time-scales from the core to the ice shell of hundreds of years in contrast to purported transit time-scales of weeks to months.

MHD mixed convective stagnation point flow of nanofluid past a permeable stretching sheet with nanoparticles aggregation and thermal stratification

Using a thermally stratified water-based nanofluid and a permeable stretching sheet as a simulation environment, this research examines the impact of nanoparticle aggregation on MHD mixed convective stagnation point flow. Nanoparticle aggregation is studied using two modified models: the Krieger–Dougherty and the Maxwell–Bruggeman. The present problem's governing equations were transformed into a solvable mathematical model utilizing legitimate similarity transformations, and numerical solutions were then achieved using shooting with Runge–Kutta Fehlberg (RKF) technique in Mathematica. Equilibrium point flow toward permeable stretching surface is important for the extrusion process because it produces required heat and mass transfer patterns and identifies and clarifies fragmented flow phenomena using diagrams. Nanoparticle volume fraction was shown to have an impact on the solutions' existence range, as well. Alumina and copper nanofluids have better heat transfer properties than regular fluids. The skin friction coefficients and Nusselt number, velocity, temperature profiles for many values of the different parameters were obtained. In addition, the solutions were shown in graphs and tables, and they were explained in detail. A comparison of the current study's results with previous results for a specific instance is undertaken to verify the findings, and excellent agreement between them is observed.

Perception of Farmers Regarding Climate Change: A Comparative Study of Hisar and Shimla

The term climate stands for general weather conditions prevailing over a period of many years, while climate change refers to significant variation in average weather conditions during a long time period that may be several decades or more. Agriculture is the major source of livelihood for almost 60% of the India's total population. Its different regions are highly vulnerable to various natural disasters like avalanches, earthquakes, floods, drought etc. stressors of water resources” [1]. The present comparative study was conducted in the purposively selected Haryana state and Himachal Pradesh state. One district from each state i.e., Hisar from Haryana and Shimla from Himachal Pradesh were selected at random. A total sample of 240 farm families, 40 from each village (total six village, 1 village from each block) was selected purposively comprising of 120 farm families of Hisar district and 120 of Shimla district. The result was analysed by the statistical tools viz., frequency, percentage, weighted mean score, spearman;s rank correlation and mean. Result showed that in both Haryana and Himachal Pradesh, maximum respondents were familiar about the term climate change but they were unaware about many related terms. Result also elucidated that increasing population and food and water scarcity were perceived most important threat in Haryana and economic situation and unemployment & poverty, food and water scarcity were most important threats perceived in Himachal Pradesh and in Haryana maximum changes were noticed in terms of extreme heat and cold and pattern of rainfall whereas, in Himachal Pradesh maximum changes were observed in pattern of rainfall and season shift. Result also observed that in Haryana most important problem caused by global warming included heat waves which ranked first followed by lesser rainfall and water shortage ranked second and third respectively while in Himachal Pradesh most important problems included lesser snow with ranked first followed by lesser rainfall (rank II) and reduced lake ice cover (rank III).

A Remote Triggered Compound Parabolic Collector for Thermal Engineering Studies

Solar thermal energy systems are one of the most cost-effective renewable energy systems in use today. Engineering students study the design of these systems with the goal of learning how to design similar systems and perform research on improving the heating efficiency and overall operations. This paper elaborates on the design, construction, testing, and validation of a solar thermal system as a remote, open instrumentation lab, using two Compound Parabolic Collector (CPC) evacuated tube collectors with separate heating media. The lab allows for comparing heat transfer rates and collector efficiencies simultaneously for two fluids that have different thermal capacities. The heat patterns could be viewed using thermal cameras to analyze the CPC design. The unique feature of the system is its facility to control the lab remotely, as the setup is interfaced with instrumentation on a web server, thereby allowing students from geographically distant areas to access and perform experiments on the CPCs. A cumbersome lab with expensive hardware and outdoor requirements is thus made easy to perform and learn from via remote access. This remote methodology and hardware and IT architectures are especially pertinent and relevant in the blended and remote learning scenarios made common by the pandemic.

A cross-sectional survey-based study of the cold and heat pattern of recovering patients after COVID-19 at the University medical center at Ho Chi Minh City branch 3 and students of the faculty of Traditional medicine, University of Medicine and Pharmacy at Ho Chi Minh City.

Due to the surge of the post-COIVD-19 patients, numerous publications were recently presented, including applying Traditional Chinese medicine (TCM) in accelerating recovering pace. However, most TCM studies mainly focused on interventions and their effect on the patients. In the general characteristic of the post-COVID-19 syndrome in TCM, this study identified the relationship between post-COVID-19 syndrome and cold–heat patterns, one of the essential principles of the Eight Principles in TCM. We established a cross-sectional study on 384 participants at University Medical Centre HCMC - branch No.3 and the faculty of Traditional medicine, UMP, from January 2022 to April 2022 (including outpatients, inpatients, and students). A questionnaire was built to collect data on socio–demography, post-COVID-19 status, and cold-heat patterns. Cold-heat patterns were gathered based on the “Cold and heat patterns identification questionnaire” developed by Yeo M et al. (2016). All eligible participants were free to choose a suitable interview method, including by phone, by URL link, or by face-to-face interview. We enrolled 384 eligible patients, and 17 samples were removed due to missing. The median age was 33 (24 - 42) and the median BMI was 21.97 (19.78 – 23.88), and females took up to 62%. We found the relationship between gender and cold-heat pattern with post-COVID-19 status (p<0.05). The relevance of post-COVID-19 status and cold–heat patterns took the first step in comprehensively observing general TCM characteristics of the post-COVID-19 syndrome.

Influence of coil shapes on temperature distribution in induction heating process

Induction heating technology has been widely applied in industrial applications like preheating, brazing, and melting furnaces. In induction heating, eddy currents are induced internally in the workpiece, restriction in these eddy currents due to resistance of material dissipates energy and generates heat into the workpiece. In these processes, obtaining desired temperature profile for homogenized processing of the workpiece can be a very challenging task, here coil geometry can play a significant role in the resulting temperature distribution obtained on the workpiece. This paper provides an improved knowledge of the induction heating process through numerical simulation as well as helps in understanding the relationship between magnetic flux density distribution and resulting heating patterns. Four different shapes of the helical coil including classical, conical, square, and oval are analyzed. Their resulting magnetic fields and temperature control profiles are computed using the finite element method. Results obtained show that different shapes of coil produce different heat patterns. These results can be further applied to predict the heating zones and assist in designing induction heating coils for the induction heating applications like thixoforming, in order to achieve desired temperature profiles.

Evaluation of Usefulness of Infrared Thermography for the Detection of Mastitis Based on Teat Skin Surface Temperatures in Dairy Cows

Given the severe economic losses due to mastitis, the identification of a diagnostic tool that can rapidly screen cows suspected of mastitis immediately before milking would be especially advantageous for farmers owning a large number of dairy cows. It is important to detect mastitis at an early stage to ensure effective and successful prevention and management of intramammary infections. Therefore, this study evaluated utility of Infrared Thermography (IRT) as a diagnostic tool for mastitis based on the heat patterns of thermal images. We found that 49 (1–4 teats in 16 cows) of the 252 teats were suspected of mastitis and 203 teats appeared normal. Our results showed that cows suspected of mastitis presented teat skin surface temperature (TSST) values that were 5.05°C higher, on average, then those of healthy cows. Moreover, TSST values were well correlated with both high somatic cell count values (r=0.99; P<0.001) and California mastitis test scores (r=0.59; P<0.001), indicating that TSST temperature monitoring using IRT could represent an easy and reliable method for screening for mastitis in dairy cows breeding farms.

Моделирование совмещенного нагрева для абляции опухолей

In the field of oncology therapy in the last few decades, methods of local thermal destruction have been intensively developed, which is heating a malignant neoplasm to a coagulation temperature and above. Among them, radiofrequency ablation (RFA) and microwave ablation (MWA) are the most common. The main problem of the existing MWA and RFA units is the insufficient degree of tissue coagulation. Depending on the type of tissue, various methods of exposure to an electromagnetic field can be used. In the radio frequency (RF) range, ohmic heating can be used, suitable for highly conductive tissues, and dielectric heating for low conductivity tissues. To increase the heating volume, it is proposed to combine ohmic and dielectric heating. The purpose of this work was to study the possibility of combining the processes of ohmic and dielectric heating based on methods of microwave and radiofrequency thermal destruction. A computer simulation of the combined heating electrode was carried out. The COMSOL Multiphysics software package was used to create the model. The algorithm for constructing the model consisted in creating the geometry, choosing the sizes of the working zones of the electrodes, setting the power parameters and imposing a finite element mesh. The model was two-dimensional. Various configurations of the combined heating electrode were considered. As a result, it was found that it is possible to create a heating area of a larger volume than with separate exposure. The overall shape of the resulting heating in all cases had an elliptical shape. At the same time, the heating pattern for RF working zones with a size of 5 mm had a shape more suitable for the treatment of spherical tumors than for working zones with a size of 10–20 mm. The results obtained demonstrate the possibility of increasing the heating volume by more than 40% compared to single operating modes. The most suitable sizes of RF heating zones are calculated, at which the heating volume will be maximum. The use of combined heating in clinical practice will partially solve the problems of insufficient heating volume inherent in the single-electrode heating mode in both RFA and MWA.

The influence of interlaminar microstructure on the induction heating patterns of CFRP laminates

The impact of interlaminar microstructure on the induction heating patterns of CFRP laminates is investigated using thermography technique. Different consolidation methods were used to obtain the varying interlaminar distances. When excited by a circular induction coil, the induction heating pattern of laminates shifted from a circular to a rectangular shape as the interlaminar distance increased. The shift in the heating patterns is caused by the increase in fiber separations at the interface, which leads to fewer electrical contacts. The effect of varying interlaminar distance was modeled as an effective through-thickness electrical conductivity in the numerical model. When the separation between the fibers increased from 8 ± 3.6 µm to 15.3 ± 3.8 µm, the ratio of junction heating to fiber heating increased from 60% to 135%.