Peak Temperature Values Research Articles

Athabasca Toe-to-Heel Air Injection Pilot: Evaluation of the Spontaneous Ignition Based on Apparent Atomic Hydrogen-Carbon Ratio Variation

Summary An in-depth analysis was performed to determine the ignition delay via the enhanced spontaneous ignition (ESI) method on three well pairs (each pair constituted by one vertical injector and one horizontal producer) belonging to the Toe-To-Heel Air Injection (THAI) pilot in Athabasca. ESI consisted of preheating of the surroundings of injection wells by injecting a steam slug for 3 to 4 months just before starting air injection. At first, the ignition delay had been determined based on both the oil production and on the bottomhole temperatures (BHTs) recorded in the observation wells as well as at the toe of the horizontal producer. For the purposes of this paper, a more rigorous evaluation was carried out based on the variation in time of the apparent atomic hydrogen-carbon ratio (AAHCR) calculated from detailed gas analyses for a long period of time. AAHCR is a very strong synthetic parameter giving a direct indication of the peak temperature value before, during, and after the in-situ combustion (ISC) front is generated. Therefore, it provides complete information on the occurrence of high-temperature oxidation and low-temperature oxidation (LTO) reactions. Using the variation of the AAHCR, it was found that the ignition time was shorter than those determined by the previously mentioned methods. In the case of first well pair, ignition took 3 weeks as compared to the 1 month determined by the previous methods. The second well pair ignited in 1 month as compared to the previously calculated 2 months, and for the third well pair, ignition time was approximately 2 months in both cases. As an additional and complementary approach, estimation of the ignition time was also based on the variation of individual components of the produced gas. This allowed for the discovery of a new method for ignition time determination. This was possible in the THAI process, unlike conventional ISC processes, significant concentrations of hydrogen (H2) are produced, and the interpretation of its variation can give an indication of the ignition time. The new method is very simple to use, as the percentage of hydrogen in the produced gas starts to take off only after the full establishment of an ISC front, as hydrogen production is associated with high-temperature bond scission reactions in the ISC front. In general, the ignition delay is overestimated to some degree when using this method.

Properties of different varieties of Maranta arundinacea’s starch.

The objective of this study was to analyze and compare arrowroot starch varieties of the "seta" (AS) and "redonda" (AR) varieties by assessing their chemical, morphological, rheological, structural and thermal characteristics, and verifying their applicability in the food industry. This research involved: proximal composition (moisture, ether extract, crude protein, crude fiber, ashes and glicidic fraction), infrared spectroscopy, scanning electron microscopy, determination of paste clarity and properties, X-ray diffraction, and thermal properties. The extracted starches have high purity, having low levels of the components analyzed in the proximal composition. The main chemical groups found in polysaccharides were determined in infrared spectroscopy. Both arrowroot starches exhibited fragility to high temperatures, lower resistance to dissociation of hydrogen bonds, and high final viscosity. The characteristic size of the starch granules is in the range of 8 μm to 45 μm, with a predominance of granules of approximately 30 μm, for both AR and AS, which can be considered large granules. The granules predominant geometric shapes are oval and ellipsoid Starches exhibited type-C crystallinity and initial, peak and final temperature values for gelatinization were well below the temperatures found in literature. The two starches exhibited potential for use in the industry of instant foods, breakfast cereals, infant food, meat products, and bakery products.

Application of The Ahp For Optimization of Weld Strength of Al-8%Sic Composite Using Pctig Welding

Here Analytical Hierarchical Process (AHP) was used for optimization of weld strength of Al-8%SiC composite using Pulsed Current Tungsten Inert Gas (PCTIG) welding. The experiment was designed using Taguchi L9 OA. The parameters used as criteria were pulse on time, pulse frequency, peak current, base current, peak temperature and cooling rate. The optimum condition were at peak current of 160A, base current of 60A, pulse on time of 50%, pulse frequency of 5Hz and optimum values of peak temperature and cooling rate were 446°C/s and 20°C/s respectively.

The effect of light on sleep quality and physiological parameters in patients in the intensive care unit

BackgroundIf patients in the intensive care unit are constantly exposed to artificial light, various problems related to sleep, and circadian rhythm may develop. ObjectivesThe aim of this study was to determine the effect of light in the ICU on sleep quality and physiological parameters of patients. DesignExperimental and randomized-controlled trial. MethodsThe study was conducted in the ICU of a training and research hospital between May 2019‐March 2021. The patients hospitalized in the ICU constituted the population of the study, and 148 patients constituted the sample calculated by power analysis. In individuals allocated into the experimental and control groups according to randomization, a cyclic lighting system was organized in isolation rooms for the experimental group, and a standard ICU lighting system was used in the control group. ResultsThe durations of deep sleep, light sleep and total sleep in the experimental group were statistically significantly higher compared to the control group (P < .05). No statistically significant difference was found in terms of systolic and diastolic blood pressure, peak heart rate and body temperature values in the experimental and control groups according to 48-hour sleep duration (P > .05). The 48-hour respiratory rate values in the ICU were statistically significantly higher in the control group compared to the experimental group (P < .05). ConclusionIt was determined that the light in the ICU affected the sleep quality and physiological parameters of individuals. It is recommended to make environmental arrangements for light according to human biorhythm and to reduce exposure to artificial light in order to increase sleep quality and sleep duration in the ICU. Trial registration numberNCT0466142.

Numerical Investigation on the Effect of Cylindrical Combustion Chamber Diameter-to-Depth Ratio on the Performance of Stoichiometric Natural Gas Engine With Exhaust Gas Recirculation

Abstract In this study, three cylindrical combustion chambers with different diameter-to-depth ratios were designed to accelerate the flame propagation and enhance the combustion ratio of CH4 in a stoichiometric natural gas engine with exhaust gas recirculation (EGR). The effects of the diameter-to-depth ratio on the combustion and emission and the interaction between the flow field distribution and flame propagation were investigated numerically. The results showed that the value of the swirl ratio and turbulent kinetic energy (TKE) near the top dead center (TDC) could be increased continuously with a smaller diameter-to-depth ratio, which was conducive to promoting the uniform flame spread in the radial direction and enhanced the combustion efficiency. The peaks of pressure, heat release rate (HRR), and temperature dramatically increased by using the cylindrical chamber with a higher swirl ratio and higher TKE in the stoichiometric natural gas engines, thereby allowing more fuel energy to be released near the TDC in the chamber. The cylindrical chamber with the diameter-to-depth ratio of 2.36 displayed a higher peak value of combustion pressure and temperature, smaller CH4 and CO emissions, but more NOx emission, compared to other chambers. Moreover, the raised bottom bulge of the piston distorted the flame front, which accelerated the flame speed in the vertical direction. The CA50 was therefore advanced to the TDC. Thus, the cylindrical chamber with the increased squish area and the raised bottom bulge was conducive for the stoichiometric natural gas engine with EGR.

Improving High-Temperature Cycle Stability and Rate Performance of LiNi0.82Co0.11Mn0.07O2 Cathode Materials Using Hydrogen Peroxide Solution Washing System

In this study, for the removal of residual lithium (Li2CO3,LiOH) from a nickel-rich cathode material surface, LiNi0.82Co0.11Mn0.07O2 cathode materials were washed with an aqueous solution of hydrogen peroxide (H2O2).H2O2 ( pH6.04), a weak acid, can easily decompose Li2CO3 and LiOH as an oxidizing agent. On titration of residual lithium, the amounts of LiOH and Li2CO3 are 390 and 605ppm,25 - and 47 -times lower, after H2O2 washing compared to 10,296 and 28,440ppm, respectively, in case of cathode materials before washing. On DSC thermal analysis, the peak temperature and calorific value of the cathode material washed with H2O2 were 245.5∘C and 602.0 J/g, respectively, whereas the bare case was 208.6∘C and 1,071 J/g, respectively. Therefore, H2O2-washed LiNi0.82Co0.11Mn0.07O2 cathode materials had higher capacity heat retention after 100 cycles at 55∘C(85.6% at 0.5C) than the bare LiNi0.82Co0.11Mn0.07O2 cathode materials (78.6% at 0.5C).

Effect of Different Combustion Modes on the Performance of Hydrogen Internal Combustion Engines under Low Load

Detailed hydrogen–air chemical reaction mechanisms were coupled with the three-dimensional grids of an experimental hydrogen internal combustion engine (HICE) to establish a computational fluid dynamics (CFD) combustion model based on the CONVERGE software. The effects of different combustion modes on the combustion and emission characteristics of HICE under low load were studied. The simulation results showed that, with the increase in excess hydrogen, the equivalent combustion and excessive hydrogen combustion modes with medium-cooled exhaust gas recirculation (EGR) dilution could improve the intensity of the in-cylinder combustion of HICE, increase the peak values of pressure and temperature in the cylinder, and then improve the indicated thermal efficiency of HICE under low load. However, larger excessive hydrogen combustion could weaken the improvement in performance; therefore, the performance of HICE could be comprehensively improved by the adoption of excessive hydrogen combustion with a fuel–air ratio below 1.2 under low load. The obtained conclusions indicate the research disadvantages in the power and emission performances of HICE under low load, and they are of great significance for the performance optimization of HICE. Furthermore, a control strategy was proposed to improve the stability of HICE under low load.

Multi-objective optimization of disc brake structure based on heat transfer performance

As an important basis for its structural optimization design, the heat transfer performance has a key influence on the reliability of automobile brake. Based on the finite element method, the transient heat transfer of automobile disc brake is analyzed under the condition of dynamic convection heat transfer coefficient. According to the simulation results, the CCD (Central Composite Design) sampling scheme is used to transform the optimization variable and target variable into multiple design points in the decision space. The optimization variable includes the total thickness, the height of the ventilation slot, the angle between the sides of the ribs, the number of ribs while the target variable includes the mass and temperature peak. According to the multiple quadratic regression model, the response surface function is constructed, and the approximate model of optimization analysis is obtained. The error analysis shows that the response surface function is equipped with good fitting accuracy. In order to facilitate the extremum search, the optimization of the quality is transformed into the constraint condition, and the multi-objective optimization problem of the brake disc is transformed into the single objective optimization problem. Through the sequential quadratic programming method, the Pareto optimal solution set of the optimal mathematical model is found. The results show that the temperature peak value is reduced by 7.8 % under the condition where the quality of the ventilation plate is basically unchanged. By weighting the Pareto optimal solution sets of different quality intervals, a good result evaluation of ventilation panel optimization is achieved.

Development of deeply focused microwave lens applicator for efficient hyperthermia treatment

In this paper, a deeply focused microwave lens applicator is investigated for hyperthermia treatment. The lens applicator consists of a double spiral antenna (DSA) and frequency selective surface (FSS) as superstrate. The double spiral structure is designed on the top of the upper substrate (Substrate-1), the slotted ground plane is placed between the upper and lower substrate (Substrate-2), and the microstrip feed line is printed on the bottom of the lower substrate. The overall size of the proposed antenna is 32 × 32 × 3.27 mm3. Moreover, an FSS structure (as superstrate) is designed, which has a size of 64 × 64 mm2 (consists of a 4 × 4 unit cell). The FSS structure behaves as a lens that converts the bidirectional field pattern of DSA into the unidirectional pattern, which improves the focusing ability of the proposed applicator towards the phantom. The lens applicator is simulated with heterogeneous phantom (layers of skin, fat, and muscles), and the performance of the applicator is evaluated in terms of specific absorption rate (SAR), penetration depth (PD), and effective field size (EFS). The lens applicator is fabricated and experimentally validated in the presence of an artificial phantom. The measured results are in close agreement with the simulated one. Further, the performance of the applicator is analyzed for a deeply placed irregular-shaped tumor (at 15 mm from the skin surface). The study of temperature distribution is done, and the peak value of temperature is obtained as 43 °C with 2.5 W of microwave power given to the antenna. The temperature value around the tumor is obtained in the range of 41–45 °C, which is suitable for effective hyperthermia treatment.

Modelling of Phase Transitions and Residual Thermal Stress of CTBN Rubber Modified Epoxy Resins during a Pultrusion Process

Abstract The implicit finite difference and fourth order Runge-Kutta method are used both to solve the heat transfer problem in the pultrusion reaction and to calculate the temperature and conversion distributions within a thermoset composite profile. The aim of our work is to study the influence of a rubbery phase added to the epoxy matrix in production conditions. The results have shown that the rubber modified systems have a low exothermic temperature peak value, so that neither the amount of cured resin nor the final product properties are limited. First of all we will show that the phase transition (gelation and vitrification) zones within the die change as the amount of rubber varies in the resin. The relationship between the position and of these zones and the resin systems will be discussed. We calculate the residual thermal stresses for all the investigated fibre/resin systems, showing a reduction when the rubber amount increases in the epoxy blend.

Simulation study on in-cylinder combustion and pollutant generation characteristics of PODE/methanol blends

In order to cooperative control particulate matter (PM) and nitrogen oxides (NOx) emissions from compression ignition engines, the coal-based oxygenated fuels polyoxymethylene dimethyl ethers (PODE) and methanol are selected as diesel alternative fuels. The numerical model of in-cylinder combustion is established by CFD simulation platform coupling PODE/methanol chemical reaction mechanism and then in-cylinder combustion and pollutant generation of PODE/methanol blends under various methanol ratios, fuel injection parameters and intake pressures conditions are calculated and analyzed. Results show that compared with pure PODE, the maximum combustion pressures of the blends with 30% methanol increases by 3.7%, the combustion duration is shortened by 1.2°CA, and NOx emissions decrease by 16.1%. Soot emission of the blends decreases with the increase of methanol ratio. Both the advance of injection timing and the increase of injection pressure lead to the increased peak values of in-cylinder pressure and temperature of the blends, the advance of combustion heat release starting point, the reduction of combustion duration and the increase of NOx emissions. However, soot emission shows an overall downward trend. The increment in intake pressure significantly reduces the in-cylinder temperature and the emissions of NOx and soot, which effectively alleviates the trade-off relationship between NOx and soot.

Measurement of electron density and temperature in an annular magnetically confined cold-cathode plasma of helium by optical emission spectroscopy

Magnetically confined cold-cathode plasmas in monatomic gases like helium can be used in a variety of devices and applications. In this paper, the radial distribution of electron temperature and electron density in cold-cathode helium plasmas constrained by an annular magnetic field were studied by optical emission spectroscopy. Helium plasma was generated under different pressures (7.5, 10, and 20 Pa) and values of current (23.5 and 33 mA). The spectral lines of He I 667.8 and He I 501.6 nm were studied and the Stark broadening method was applied to obtain the radial distributions of electron temperature and electron density. The results indicate that higher radial gradients or peak values of both electron density and electron temperature could be achieved with increasing operating pressures and discharge currents. It was found that the electrons were mainly concentrated in the area of the localized cusp magnetic field near the cathode surface and the electron density decreased rapidly as with the decrease in the magnetic field.

A novel reconstruction method of temperature field for thermomechanical stress analysis of arch dams

Temperature distribution on the dam surface plays an important role in reliable thermomechanical stress analysis of arch dams. In this paper, a novel reconstruction method based on a convolutional neural network is proposed for the temperature field on the downstream surface of arch dams. The environmental variables, including solar radiation, mountain shadows, ambient temperature, and weather conditions, are considered in the reconstruction method. The temperature field of the Xiaowan dam is predicted using the proposed method and it agrees well with the monitoring data in the spatial and temporal scale. The results show that the environmental variables significantly affect the temperature on the downstream surface, and result in temporal-spatial variability of nonuniform temperature distribution. In addition, the proposed method solves the data sparseness and low-frequency acquisition problems that may miss the peak temperature values in the current monitoring system. The thermomechanical stress analysis based on the reconstructed method and finite element method is conducted, and its results illustrate that the proposed reconstructed method can give more realistic performance of the dam and predict possible thermal cracking on the dam surface.

Effects of different crop starches on the cooking quality of Chinese dried noodles

SummaryTo investigate the effects of seven starches made from different crop sources on noodle quality, Chinese dried noodles made from various reconstituted flours were prepared and analysed. Potato starch had better solubility and swelling power than the other starches, leading to higher water absorption, cooking loss and breakage ratio of the potato starch noodles. The correlation results unravelled that the cooking breakage ratio of noodles presented positive correlations with solubility, swelling power, peak viscosity (PV), trough viscosity (TV) and final viscosity (FV) values of starches. Besides, the adhesiveness of noodles showed a positive correlation with conclusion temperature (Tc) and setback viscosity (SV) values of starches. Moreover, the peak temperature (Tp) value of starches was negatively correlated with cooking loss; the granule size of starches had a positive correlation with noodles water absorption; and the peak time (PkT) value of starches represented positive relationships with noodles chewiness, shearing force and breaking strength.

Prediction of peak temperature value in friction lap welding of aluminium alloy 7475 and PPS polymer hybrid joint using machine learning approaches

In the automotive and aerospace sectors, vehicle weight has been a major concern for the past decades. Incorporating metal-polymer hybrid structures reduces weight without compromising structural performance. In this work, Friction Lap Welding (FLW) technique was used to join aluminium alloy 7475 with PPS polymer. To conduct the FLW experiments, a design matrix was developed with the help of Response surface methodology. For each experimental run, the peak temperature value was recorded. The possibility of machine learning algorithms for predicting peak temperature during joining has been assessed. The maximum correlation coefficient (i.e., 0.999) and minimum root mean square error (i.e., 0.068) were observed for the support vector machining (SVM) model with the PUK kernel. So, SVM-PUK approach was determined to be the most efficient.

Effects of typical inhibition materials on the flame propagation of pulverized coal mixture

Inert powders played an important role in the explosion inhibition of dust removal equipment and coal gasification process. In this paper, SiO2, dry water, carrageenan dry water, and NaHCO3 were adopted to explore the influences of inert powders on the deflagration flame propagation characteristics of mixed pulverized coal by a vertical pipeline. The results showed that the flame brightness of the mixed pulverized coal decreased with the irregularly discrete of flame front after the addition of inert powders. As the increasing of pulverized coal mesh number, the peak flame temperature first increased and then decreased, while the drop value of peak flame velocity and temperature increased with the increasing of mass concentration. In addition, the inerting rate affected the propagation of pulverized coal composite flame. When the inerting rate exceeded 1.0, the peak temperature drop increased rapidly and dry water exhibited the best inhibition performance.

Changes in Body Surface Temperature Associated with High-Speed Treadmill Exercise in Beagle Dogs Measured by Infrared Thermography.

Simple SummaryHeat exchange between the body surface and the external environment plays an important role in the regulation of body temperature in animals. Previous studies on the effect of exercise on the distribution of body surface temperature in dogs have been conducted on a variety of breeds and did not employ specific defined regions of interest. The aim of our research was to assess the influence of high-speed treadmill exercise on body surface temperature using infrared thermography in selected body regions of healthy Beagle dogs, taking into account gait and recovery time. The study was based exclusively on the Beagle breed, which presents short, uniform, and straight hair, conducting heat more readily from the skin. Statistical analysis indicated the highest temperature at the upper forearm and thigh, and the lowest on the croup, back, and neck. The peak surface temperature values in all examined areas were observed after the canter and the post-gallop walk, and the lowest were observed 2 h after exercise. Our study confirms that the body surface temperature of Beagle dogs is influenced by high-speed physical exercise on a treadmill as a result of muscle activity and changes in blood flow. The proximal forelimb and hindlimb were the most influenced by exercise.Evaluation of body surface temperature change in response to exercise is important for monitoring physiological status. The aim of the study was to assess the influence of high-speed treadmill exercise on body surface temperature using infrared thermography (IRT) in selected body regions of healthy Beagle dogs, taking into account gait and recovery time. Thermographic images of the dogs were taken before exercise (BE), after walk (AW), after trot (AT), after canter (AC), just after second walk (JAE), 5 min after exercise (5 AE), 15 min after exercise (15 AE), 30 min after exercise (30 AE), 45 min after exercise (45 AE), and 120 min after exercise (120 AE). Body surface temperature was measured at the neck, shoulder, upper forearm, back, chest, croup, and thigh. Statistical analysis indicated the highest temperature at the upper forearm, shoulder, and thigh, and the lowest on the croup, back, and neck. The peak values of surface temperature in all ROIs were at AC and JAE and the lowest at 120 AE. The study demonstrated that body surface temperature was influenced by high-speed physical exercise on a treadmill and IRT was a viable imaging modality that provided temperature data from specific body regions. The proximal forelimb and hindlimb were the most influenced by exercise.

Numerical Study on Subsonic-Supersonic Laval Nozzle Using MacCormack Scheme

Due to the wide application of the Delaware nozzle in many fields, the flow characteristics of the subsonic-supersonic isentropic flow in the De-Laval nozzle are analyzed numerically. The flow in the nozzle can be simplified to a quasi-one-dimensional flow problem. First, the MacCormack format is employed to discretize the control equations in conservative form. Then, the results with and without artificial viscosity are compared. Grid independence is also discussed. The results show that the numerical solution and the theoretical solution agree very well, indicating that the numerical simulation results are very reliable. In addition, a higher pressure will reduce the peak and valley values of Mach number, pressure, density, temperature and velocity in the nozzle, and these extreme values of subsonic supersonic isentropic nozzle appear earlier. Additionally, the shock wave is accurately captured, and the shock wave is behind the throat. This research is of great significance to understand the flow characteristics in the nozzle.

3-D modelling of the coaxial one-side resistance spot welding of AL5052/CFRP dissimilar material

Coaxial one-side resistance spot welding (COS-RSW) is an advanced technique for joining CFRP/metal dissimilar materials. In the present work, a three-dimensional model was developed based upon an in-house finite element code JWRIAN-SPOT to simulate the multi-physical process of the COS-RSW. The thermal cycle and joining strength of COS-RSW joints with different welding parameters were measured experimentally. The sensitivity of material properties of electrode couple and component of accumulated heat generation were discussed in detail. The predicted thermal cycles presented a reasonable agreement with measurements, which also explained the influence of welding parameters on temperature field. The joining strength of COS-RSW joints can be evaluated qualitatively via the area of effective molten zone, which reached about 20 MPa with a 4800 A welding current. The column and cylinder electrodes determined the peak value of interface temperature and molten zone area, respectively. The cylinder electrode was suggested to be fabricated by a high resistivity material to generate sufficient Joule heat. Moreover, the SUS304 electrode and its contact zone provided more than 70% of the entire heat generation. The materials of electrode couple should be determined carefully when employing COS-RSW for joining CFRP and other metals. • A 3-D model of COS-RSW was established based upon an in-house finite element code JWRIAN-SPOT • The joining strength of COS-RSW joints shows similar variation tendency to the area of effective molten zone • The column and cylinder electrodes determine the maximum interface temperature and molten zone area, respectively • The SUS304 electrode and SUS304-AL5052 interface generate more than 70% of the total Joule heat

Impact of variation of solar irradiance and temperature on the inverter output for grid connected photo voltaic (PV) system at different climate conditions

The main purpose of this paper is to observe the effect PV variation of solar temperature and irradiance on different conditions and on the inverter output for a grid-connected system. Majorly temperature& solar irradiation effects the performance of a grid connected inverter, also on the photo-voltaic (PV) electric system. Thesimulation basedstudy was carried out in order toevaluate the variation of inverter output with the variation of solar temperature and irradiance with the variation in climate. The analysis of Grid-connected inverter and their performance at various seasons and conditions is investigated. Solar power plantfor a year. In solar power plant efficiency of inverter is also considered to calculate overall losses so, the inverterefficiency and plant performance are considered in this paper using MAT Lab software. In summer season the inverter performed efficiency is decreased because of peak temperature value and slightly increased with the increase in irradiance.