Differences In Temperature Changes Research Articles

Performance Analysis of Fuzzy Logic Controller Applied on Portable Roaster

Roaster is a device commonly used to roast various products, especially for food processing. In the roasting process, temperature parameter plays a major role in determining the final quality of the roasted product. In real-world applications, some products must be roasted at low temperatures such as cocoa products and others must be roasted at high temperatures such as coffee products. In addition, roasting is sometimes not always carried out at a constant temperature, but sometimes it must be done at various roasting temperature levels for the purpose of forming the optimal flavour. Thus, a roaster must be able to operate at the desired operating temperature, not only a constant operating temperature but also able to work with varying operating temperatures. For this purpose, a roaster must be equipped with a reliable temperature controller. Several control models have been developed by many researchers, including fuzzy logic control. This research was conducted to design, implement, and evaluate the performance of a control system based on fuzzy logic on a laboratory scale portable roaster. For this study, a fuzzy control system with two input variables, namely the difference in temperature and changes in temperature difference as well as one control signal output variable, had been designed to regulate the roasting temperature on the roaster. To evaluate its performance, the domain membership function of the input and output variables was varied. The design was then applied to the microcontroller-based control system hardware attached to the portable roaster. The test results show that the fuzzy logic control was able to regulate the roast temperature stably. With a varied roast temperature setpoint, the control system can follow and maintain the target with small temperature variation.

Investigation on the induction brazing of copper–steel tubes with different coil structures

The purpose of this study is to investigate the effect of coil structure on electromagnetic fields and temperature distributions of copper–steel tube induction brazing for compressor-automatic production line. To get a satisfied temperature distribution, five coil structures were designed and three-dimensional finite element models were established. The temperature distribution of the workpiece was numerically predicted and compared with the experimental values, and the simulated temperature field shows very good agreement with the experimental temperature measurements on the workpiece surface. The simulated results revealed that the coil structure was crucial and considerable to the thermal field of the workpiece and heating efficiency. Moreover, different materials have large differences in temperature change when heated by the same coil. To ensure good quality of the joints and high productivity, a reasonable heating time of rapid induction brazing was obtained at about 4 s. The comparison results indicated that the coil structure of square ring with series connection demonstrated the highest performance in terms of heating efficiency and energy usage among the coil designs.

Research on the Defrosting System of Refrigerated Containers Combining Air and Electro-Thermal Energy and the Controlling Strategy

Considering the problems such as long duration of defrosting, low working reliability and high energy consumption of refrigerated containers, this paper put forward a new defrosting method combining air and electro-thermal energy, and designed a new defrosting structure system based on the structural features of refrigeration modules of refrigerated containers. The two-variable method of wind pressure change and temperature difference change on both sides of the evaporator was used to detect frosting, and the specific controlling strategy supporting the new defrosting system was provided to realize the effect of intelligent defrosting. It can provide references for fast defrosting, intelligent defrosting and low energy consumption defrosting of refrigerated containers.

Comparative Effectiveness of Two Light Curing Units on the Properties of Dental Resin Composites

Background: Setting of conventional glass ionomers cement and dental resin composites as filling materials is predominantly through polymerization reaction, which is usually induced by light. The objective of this study was to assess the temperature changes, light intensities, sorption and solubility capability and comparative micro hardness in Dental Resin Composites (DRC) by using two different light curing units that is Quartz Tungsten Halogen (QTH) and Light Emitting Diodes (LED). Methods: This analytical, experimental, in-vitro study was spanned over one month, conducted in the laboratory of Dental Materials, Dr. Ishrat-ul-Ibad Khan Institute of Oral Health Sciences. Through non-probability, convenient sampling, 60 samples of DRCs was prepared as 10mm in diameter and 2mm in thickness in the steel moulds by a single trained operator. Effect of heat generation, light intensities, sorption and solubility and micro hardness during polymerization of DRCs were all measured. Statistical analysis was done using SPSS with descriptive statistics and two sample independent t-tests. The p-value of <0.05 was considered significant at 95 % confidence level. Results: Mean surface micro hardness of DRC was found to be 15.48±0.46 and 18.26±0.53 when QTH and LED lamps were employed respectively. Whereas, mean light intensity of QTH and LED lamps were found to be 434 and 925mW/cm2. No significant difference in temperature change during polymerization reaction (p=0.128) and in sorption and solubility capability (p=0.001) of DRC was observed. Conclusion: Light-emitting diodes were evaluated to be more effective than Quartz Tungsten Halogen Light in achieving increased surface micro hardness of DRC. Keywords: Light; Glass Ionomer Cements; Tungsten; Hardness.

Analysis of nonlinear bioheat transfer equation in magnetic fluid hyperthermia

The objective of this study is to examine the role of blood perfusion in magnetic fluid hyperthermia by drug delivery. Although increasing blood perfusion due to high local temperature difference refers to the intelligent response of the human body, some researchers are accustomed to employing a constant rate of blood perfusion in the bioheat transfer equation. In this study, we considered a variable volumetric rate for blood perfusion in tissue, experimentally and numerically by Galerkin method. To validate the results obtained from numerical methods, an experimental procedure proposed. Furthermore, in order to transfer magnetic fluid by drug delivery, infusion pomp by which the saline serum with nanoparticles through the vein and artery was employed to make a spherical distribution in tissue. This circulation made it possible to transfer nanoparticles to tissue without any injection. After 60 minutes and changing the dark color of the saline serum to light clear, high amount of nanoparticles (about 90 %) was transferred to the tissue. After slicing the tissue, the rather spherical distribution of nanoparticles may be illustrated. Afterward, that circulation at the rate equal to blood perfusion has been made to simulate blood perfusion in dead tissue. To measure temperature, seven Lm35 sensors have been inserted into the tissue to report temperature differences. Based on results, there was seen a significant change in hyperthermic temperature difference in comparison with results obtained from Pennes’ bioheat transfer equation. Additionally, a difference of about 5–10 % was seen between numerical and experimental results.

Simulation of a single-stage evaporator system integrated with a mechanical vapor compressor for concentrating the electrolytic system KNO3 – H2O

A simulation of a single-stage evaporator system integrated with a mechanical com- pressor for a case study (concentrating the electrolytic system KNO3 – H2O) was performed. A mathematical model of the subsystem of a single-stage evaporator, a mechanical compressor, and superheated steam seeding is presented. Microsoft Excel with VBA (Visual Basic for Application) was used to solve the mathematical model. The model was solved by an iterative method where the values of the in- let stream temperature and the salt concentration in the concentrated stream at the evaporator outlet were assumed. The process parameters of the system have been determined. Since the goal of any industrial process is to minimize costs and maximize products, the impact of mean temperature difference changes on satu- ration water consumption and molar salt content in the concentrated stream was presented. 106.92 kg/h of freshwater are required to obtain 18% by weight of salt in a concentrated stream, while 432.30 kg/h of fresh water are required to obtain 25% by weight of salt in a concentrated stream. Consumption of heating steam ranged from 1760.31 to 4473.4 kg/h depending on the average temperature dif- ference. By increasing the temperature differences from 10 to 25 ◦C, the amount of transferred upper lines increases from 1025 to 2750 kW, which is an advantage of increasing the mean temperature difference. The disadvantage of the larger tem- perature difference is the increase in the power of the mechanical compressor from 97.02 to 384.12 kW.

Realization of Constant Voltage Anemometer Using an Alternative Signal Conditioning Circuit

Anemometric method is the most accurate and reliable technique for air velocity measurement. In present work, a voltage follower based circuit is proposed, and a low-cost sensor (tungsten filament) is chosen to perform Constant Voltage Anemometer (CVA) operation for air velocity measurement. For performing the real-time experiment, a wind tunnel featuring a rectangular section (test section I) and a circular section (test section II) with a provision for low-cost sensors and a reference Hot Wire Anemometer (HWA) was fabricated. The measurement is repeated multiple times for various air velocities in the range of 3 m/s to 12 m/s. The estimated ‘pdr’ value (ratio of the power dissipated in the sensor, Pw to the difference between heated sensor resistance, Rw and the sensor resistance at ambient temperature, Ra), considered as new output voltage, is analogous with the output voltage (Vo) of the proposed circuit. The range of ‘pdr’ in test sections I and II is 0.033 mW/Ω to 0.867 mW/Ω and 0.0062 mW/ῼ to 0.1059 mW/Ω, respectively. Similarly, overheat ratio, OHR (ratio of the difference between heated sensor resistance, Rw and the sensor resistance at ambient temperature, Ra to the sensor resistance at ambient temperature, Ra) estimated, is also found to be analogous with the change in temperature (difference between the temperature of the heated sensor Tw and the ambient temperature Ta). The range of OHR in test sections I and II is 0.709 to 0.660 and 0.678 to 0.647, respectively. Uncertainty analysis is carried out for the proposed voltage follower based CVA measurement system and the expanded uncertainty with a 95% confidence level is obtained as 0.54 for the whole range of air velocity measurement.

External Fixation Devices Within the Magnetic Resonance Imaging Bore: A Safety and Radiologic Analysis.

To (1) report the thermal changes encountered at the pin/skin interface in a cadaver with a knee-spanning external fixator inside the magnetic resonance imaging (MRI) bore and (2) report on the quality of the MRI sequences collected. Three commonly used external fixation systems were placed on cadaveric lower extremities to simulate knee external fixation. Fiber optic thermal probes were placed at the pin/skin interface of a femoral and tibial pin. A control probe was embedded in the soft tissues of the thigh. Full knee MRI scans were performed using a 1.5-Tesla magnet. Real-time thermal data were collected. A clinically significant increase in temperature compared with the control was defined as 2°C. Two blinded radiologists evaluated the images for image quality and overall diagnostic utility using a standardized 5-point grading scale. There were statistically significant differences in the temperature changes between the femoral/tibial pin sites and the control probe sites during each phase of the MRI scan. However, there was only one clinically significant difference in temperature change during a single sequence of one MRI scan of one of the external fixator devices. Overall image quality was graded as a 4 for each image set with 100% interobserver agreement (k = 1.0). Despite significant differences in temperature changes between the pin sites and controls over multiple MRI sequences in commonly used external fixator devices, the differences in temperature change are likely not clinically relevant. Overall image quality and interpretability of the images were excellent.

Spatio-temporal differentiation of climate warming (1959–2016) in the middle Qinling Mountains of China

Based on air temperature observation data from 32 meteorological stations, temperature changes in the middle Qinling Mountains from 1959 to 2016 were analysed with respect to the north-south, seasonal and altitude differences. Our research mainly showed the following results. The annual temperature (TA) rose approximately 0.26°C/10a within the past 58 years. This warming trend was stronger on the northern slope than on the southern slope, and a warming trend reversal occurred in 1994 on the northern slope, which was three years earlier than on the southern slope. The temperature changes for the four seasons were not synchronized, and the trend in spring contributed the most to the TA trend, followed by winter, autumn, and summer. The temperature difference between summer and winter (TDSW) decreased significantly over the past 58 years. The temperature change in the middle Qinling Mountains was clearly dependent on altitude. With increases in altitude, the TA increased gradually and became stronger while the TDSW decreased gradually and became weaker. Differences in temperature change between the north and south were mainly observed in low-altitude areas. With increase in altitude, the differences gradually tended to disappear.

Simulation study on ±320kV DC power cable steady-state temperature field distribution and its influencing factors

Temperature distribution is an important parameter in the operation of DC cables, while there are few studies at present. In this paper, the steady-state temperature field distribution of DC cable was calculated by simulation, and the factors including conductor current and outer surface temperature were discussed and analyzed. The results showed that there is a temperature gradient in the radial direction of the cable; Both the conductor current and the outer surface temperature have a significant effect on the overall temperature of the cable; The increase in the conductor current and the outer surface temperature will significantly increase the conductor temperature. However, the insulation temperature difference changes little.

Experimental analysis on impact of navigator's angle on velocimetry and thermal capability of RH-vortex tube

As an interesting thermal device, the vortex tube (VT) uses the instantaneous expansion process of compressed gas to provide the conditions for cooling and heating usages. At the beginning of the entry into the vortex chamber, the compressed gas is forced to be guided in the pipe path by a piece named the navigator. This piece has a small angle to guide the gas longitudinally, and this angle has a very important effect on the efficiency of the VT. This research investigates the impact of the navigator angle (0–15 deg) on the energy separation and the internal gas velocity variations (swirl and axial). The results show that the navigator angle of 10 deg creates the highest cooling and heating capabilities as well as the highest values for the axial velocity and also for the swirl velocity drop. When the angle increases from 10 deg to 15 deg, the cold temperature difference changes from 22.32 K to 17.37 K, which indicates 22.19% decrease in the temperature difference. Also, increase in the angle from 0 deg to 5 deg leads to 4.28% and 5 deg to 10 deg leads to 1.2% improvement in the hot temperature difference. The results of the velocity measurements inside the VT are compared and confirmed by other valid researches.

Thermal performance evaluation of subcritical organic Rankine cycle for waste heat recovery from sinter annular cooler

The sinter cooling flue gas expelled from the end of an annular cooler was taken as the heat source of an organic Rankine cycle (ORC) system, and R123, R245fa, R600, R601 and R601a were selected as the working fluids of the ORC system. The effects of evaporation temperature and superheat degree of working fluid, as well as the pinch point temperature difference in the evaporator on the system thermal performance, were analyzed in detail. The results show that the system net output power and exergy efficiency for different working fluids first increase and then decrease with an increase in the evaporation temperature and decrease with an increase in the superheat degree and pinch point temperature difference. The change in pinch point temperature difference has no effect on the system thermal efficiency. For a given operational condition, the system thermal efficiency and exergy efficiency of R123 are the maximum, while the system total irreversible loss of R245fa is the maximum. When the evaporation temperature is greater than 110 °C, the system net output power of R600 is the maximum. The ORC system could obtain the maximum net output power and exergy efficiency through the adjustment of evaporation temperature of working fluid.

The effects of geometry and heating rate on thermocapillary convection in the liquid bridge

The experimental study on thermocapillary convection in liquid bridges of large Prandtl number has been carried out on Tiangong-2 in space. The purpose of these experiments is to study the oscillation instability of thermocapillary convection, and to discover and recognize the mechanism of destabilization of thermocapillary convection in the microgravity environment in space. In this paper, the geometry of a half-floating-zone liquid bridge is featured by the aspect ratioArand volume ratioVr, and its influence on critical conditions of oscillatory thermocapillary convection is studied. More than 700 sets of space experiments have been finished. The critical conditions and oscillation characteristics of thermocapillary convection instability in theAr–Vrparameter space have been fully obtained under microgravity conditions for the first time. It is found that theAr–Vrparameter space can be divided into two regions of different critical conditions and oscillation characteristics: the region of low frequency oscillation, and the region of high frequency oscillation. More importantly, we obtain the complete configuration of these two stability neutral curves, and find that the low frequency mode is a ‘’ type curve. Based on this, we discuss the influence of heating rate on the oscillation mode. It is found that the heating rate affects the selection of critical mode, which results in a jump change of critical temperature difference. The findings of this study are helpful to better understand the critical modes and transition processes of thermocapillary convection in liquid bridges with different configurations.

The Effect of Temperature on Flowback Data Analysis in Shale Gas Reservoirs: A Simulation-Based Study

During hydraulic fracturing, there is a temperature difference between the injected water and formation rock for shale gas wells. The objective of this study is to investigate how this temperature difference changes with time, and how it affects multiphase-flow modeling during the shut-in and flowback periods. We conducted numerical simulations to investigate the behaviors of fracture temperature in shale gas wells. The results show a significant increase in fracture temperature during the shut-in and flowback periods. Sensitivity analysis suggests that this temperature increase is strongly related to the thermal conductivity of formation rock, matrix permeability, and initial reservoir temperature. Simulation scenarios were further compared to investigate the effect of temperature on flowback data analysis. Without considering the thermal effect, flowback data analysis may yield an earlier fracture cleanup and overestimated fracture volume. In addition, this study suggests that the thermal effect may also have implications for optimizing flowback operations.

Temperature changes in the Heihe River Basin based on high accuracy surface modelling

AbstractIn the context of global warming, significant differences in temperature changes occur in different regions. Obtaining a more accurate temperature distribution is important for studying regional climate change. A high accuracy surface modeling (HASM) was introduced using the air temperature output from the weather research and forecasting (WRF) model as the driving field, and observation data from meteorological stations as the accuracy control conditions to obtain 30 years of high accuracy temperature fields in the Heihe River Basin. Verified by ground‐based observations, the WRF model has a limited ability to simulate temperature conditions and performs worse in low altitude areas and in winter. The fusion results of the HASM decrease the mean absolute error from 2.21 to 0.9°C and decrease the root mean square error from 2.58 to 1.16°C, thus significantly increasing the accuracy compared with the original simulation from the WRF model and resulting in a more reasonable temperature analysis. The Mann–Kendall test shows clear warming in the Heihe River Basin, but there is a mutation year of 1998 in winter and annual average. The space–time distributions of and variations in the temperature from the HASM results are also analysed by dividing the study period into three subperiods. The analysis shows consistent warming except for the winter 2001–2010 period compared with the winter 1991–2000 period, in which the northeast area of the lower reaches of the Heihe River Basin was cool. Temperature changes in the Heihe River Basin also show that the sparsely populated Gobi Desert in the north and the southern high mountains show extreme sensitivity to climate change.

Metode Selimut Insulasi Panas untuk Pencegahan Penurunan Suhu Tubuh Bayi Tikus Putih

The temperature decrease is caused by heat loss by conduction, convection, evaporation, and radiation. Various methods for preventing heat loss in newborns include the use of plastic bags. Nugraheni's research in 2016, the use of plastic wrap in newborns can still result in body heat loss because polyethylene plastic is not heated insulation. Aluminum foil is one of the ingredients that insulates heat insulation. The use of aluminum foil is widely used in various fields, for example as a food wrap to keep it warm and an emergency blanket for mountain climbers. This study aims to determine the comparison of the use of blanket heat insulation and plastic wrap in preventing the decrease in body temperature of babies of white rats. The type of research used was quasi-experimental (Quasi-Experiment) with the design of post test only control group design. The sample in this study was 30 white rats which were calculated based on Federer's formula. There were no statistically significant difference in the 15th minute p=0.221, 30th minute p=0.65 and 30th minute p=0.08, this was due to the small number of samples studied but in a systematic way, the control group's median difference was -0.1, then there was no significant difference in temperature change at 15 minutes in the blanket and plastic wrap group. In the 30th minute, the median difference in the control group was -0.5, so clinically there were differences in the blanket group and the plastic wrap group with a median difference of 0.0. In the 60th minute, the median difference in the control group was -1.2, clinically there were differences in the blanket group and the plastic wrap group with a median difference of 1.9. There is a difference in the decrease in body temperature of baby white rats using the blanket method of heat insulation and plastic wrap.

Biologging subcutaneous temperatures to detect orientation to solar radiation remotely in savanna antelope.

Observations of animal thermoregulatory behavior are labor-intensive, and human presence may disturb the normal behavior of the animal. Therefore, we investigated whether a remote biologging technique could be used to detect orientation to solar radiation in savanna antelope. We predicted that when a mammal was orientated perpendicular to solar radiation, the subcutaneous temperature on the side of the body facing the sun would be greater than that on the opposite side, whereas when the mammal was orientated parallel to solar radiation, subcutaneous temperatures on both sides would be similar. A pilot study showed that the difference between left- and right-side temperatures under a pelt reflected orientation to solar radiation if a pelt-covered cylinder had been orientated for 15 min or longer. In addition, the rate of change in temperature difference could detect orientation that had changed within the previous 5 min. We implanted temperature-sensitive data loggers subcutaneously into the flanks of eight black (Connochaetes gnu) and eight blue (Connochaetes taurinus) wildebeest. By incorporating both the rate of change and subcutaneous temperature differences and excluding times when wildebeest were lying down, our predictions correctly matched behavioral observations of wildebeest orientation to solar radiation 71% of the time. Our technique tended to fail when wildebeest were lying down, wind speeds were high and the sun was overhead. But those are conditions in which the benefits of manipulating orientation to solar radiation is of diminishing importance to a free-living mammal. Therefore, subcutaneous temperatures provide physiologically relevant information on the importance of solar radiation to mammals.

Phase change material (PCM) incorporated bricks for energy conservation in composite climate: A sustainable building solution

Sun is a perennial source of energy and utilization of this energy for building energy conservation can be a turning point in the energy saving potential of buildings. With Indian population crossing 1.3 billion, there is a need to utilize solar energy to deal with space and resource constraints. The buildings in urban areas are therefore exploring and integrating different passive techniques to conserve energy. One method of improving the energy efficiency aspects of a building would be to increase the thermal mass of the building elements by incorporating phase change materials (PCMs) within the building envelope thereby, reducing the temperature fluctuation and peak temperature within.This study discusses the competence of using PCMs for building energy conservation through their large heat storage capacities in the climatic conditions of Delhi. The aim is to experimentally study the impact of PCM incorporated bricks, assessing the change in temperature difference and heat flow across the same. Analytically for the climatic conditions of Delhi, thermally mapped Eicosane and OM35 are found suitable. These two PCMs are then experimentally characterised, to determine their melting-solidification characteristics, using differential scanning calorimeter (DSC). The results also reiterated the suitability of Eicosane and OM35. Further, the PCM incorporated bricks are tested under real conditions during peak summer (third week of May-2018). A temperature reduction of 5–6 ℃ across the bricks with respect to conventional brick was observed. Energy calculations showed reduction in heat flow by 8% and 12% for Eicosane and OM35 respectively.

Temperature changes associated with bone drilling in an orbital model: comparison of ultrasonic bone curette and conventional high-speed rotational drill

ABSTRACTPurpose: Thermal injury to the optic nerve is a potential complication of bony decompression of the orbital apex. An animal model was used to compare and contrast temperature change while removing orbital bone with ultrasonic and conventional drills.Methods: Two devices, Sonopet ultrasonic bone curette and TPS CORE Micro drill, were used to remove bone from six unpreserved exenterated porcine orbits at fixed distances from the optic canal while temperature was recorded. Increasing irrigation flow rate and decreasing saline temperature with the ultrasonic bone curette were also investigated.Results: The mean change in temperature at the optic canal using the ultrasonic bone curette with 18 ml/min 24°C irrigation was +7.2 ± 3.3°C (range 3.3–12.7°C) at 60 s, and using the rotational drill was +1.7 ± 1.3°C (range 0.1–3.3°C), representing a statistically significant increase above baseline for both drills (p < 0.01 for each). The difference in temperature change between drills was statistically significant (p < 0.01). When irrigation fluid was changed from room temperature saline (24°C), rate 18 ml/min to chilled (10°C) irrigation saline, rate 40 ml/min, the magnitude of the mean temperature increase was reduced by 3.1°C, p < 0.05.Conclusions: In this orbital decompression model, both ultrasonic and rotational drills induced a rise in temperature. This increase was significantly greater with the ultrasonic bone curette, measuring up to 13.7°C. Clinicians should be aware of the potential for temperature spikes when decompressing the orbital apex. Increasing irrigation flow rate and using chilled saline may mitigate increases in temperature.

Surface Temperature Inversions and Risk of Off-Target Herbicide Damage in the Soybean- and Cotton-Growing Regions of the US

Core Ideas Temperature inversions form most nights between 15 May and 30 June. Temperature inversions commonly form before sundown under winds greater than 3 mph. Frequency of temperature inversions in 2017 were similar to those in 2012 through 2016. The approval of the dicamba-tolerant trait in soybean and cotton as well as new dicamba spray formulations to control weeds in cotton and soybean fields has resulted in broad usage of dicamba-based herbicides. As dicamba-based herbicide usage increased, reports of non-target crop damage dramatically increased. Temperature inversions have been implicated in this off-target damage. Short-term climatologies of surface inversions at six locations across the soybean- and cotton-growing regions of the US were developed for the period 15 May through 30 June between 2012 and 2017 using National Climate Reference Network measurements. Inversions occurred most nights, occasionally collapsing and then reforming in the same night. Inversions often formed before or around sunset as the surface temperature cooled more rapidly than the overlying air. Inversion development was similar for most of the soybean-growing region with the greatest change in temperature difference between the air and the ground occurring at sundown. Higher wind speeds corresponded to decreased inversion intensity and shortened the duration of the inversion. Differences in inversion conditions in 2017 versus those of 2013–2016 were not consistent; consequently, the increased occurrence of off-target damage by dicamba in 2017 cannot be explained by an increase in the number or intensity of inversions or differences in winds during inversions. The presence of inversions when they are not expected (before sunset, after sunrise and when winds exceed 3 mph) increases the risk of unexpected off-target crop damage. Since inversions are commonly a local phenomenon, predicting inversion occurrence requires understanding the conditions at specific locations.