Search

We stated and solved the problem of determining the steady-state temperature field of a system simulated by a wall separating two different media. One of the wall surfaces has a thermally active layer that functions according to the feedback principle and features an anisotropic coating subjected to local heating while undergoing heat exchange with the environment. We show that the sought-after temperature field is an additive composition of two independent components, the first of which is exclusively a function of the heat exchange intensity between the separated media and the boundary surfaces of the system under consideration, and the second is a function of the heat flow power density affecting the separator system for the temperatures of the media separated being zero. We used integral transform methods in an analytically closed form to find solutions to respective steady-state heat conductivity problems. The results obtained confirm the existence of a previously found temperature field "drift" effect in an anisotropic material displaying general anisotropy of its properties.

The superposition equivalent loading method proposed by international standards for testing induction machines allows to conduct temperature tests at reduced different conditions than rated and extrapolate the results to rated values. Much as this test is suitable for large machines that test facilities lack capacity to test, the principle is also applicable to small machines. However, its applicability to small machines has not been extensively studied yet. Furthermore, the three types of the method categorized in the standard IEEE 112-2017 have not been compared to establish their equivalence or otherwise. This paper reports an extensive test campaign on different small size induction motors to determine both the applicability of the method to small machines and to compare the equivalence of the three types of approach. Multiple reduced voltage and reduced current selections have also been investigated to assess the accuracy of the methods for different test conditions. Test results show that all the three alternative loading methods proposed by the standard seems to be practically equivalent, whit a goodness of fit of the obtained results that tends to improve as the machine rating increases.

Recent research on mitigating thermal problems in 3D memories has covered reactive strategies that reduce memory power consumption, and thereby, performance, when the memory temperature reaches the maximum operating limit. Such techniques could benefit from temperature prediction and avoid unnecessary invocations and state transitions of the thermal management strategy. We develop an accurate steady state temperature predictor for thermal management of 3D memories. We utilize the symmetries in the floorplan, along with other design insights, to reduce the predictor’s model parameters, making it lightweight and suitable for runtime thermal management. Using the temperature prediction, we introduce PredictNcool , a proactive thermal management strategy to reduce application runtime and memory energy. We compare PredictNcool with two recent thermal management strategies and our experiments show that the proposed optimization results in performance improvements of 28% and 5%, and memory subsystem energy reductions of 38% and 12% (on average).

As an essential flavor condiment in Sichuan cuisine, Pixian Douban (PXDB) is usually produced by open fermentation process in strip pools or ceramic vats. In this study, an experiment of PXDB fermentation was conducted for 90 days in a closed system of gradient steady‐state temperature field (GSTF). To investigate the characterization of volatile compounds of PXDB in the closed system, the volatiles in three kinds of samples including samples of GSTF (SGT), samples of constant temperature (SCT), and samples of traditional fermentation (STF) were analyzed. The results showed that 75, 67, and 68 volatile compounds were detected in SGT, SCT, and STF, respectively. Compared with the traditional fermentation, the process in the closed system of GSTF was conducive to produce more kinds of esters and alcohols. A total of 22 major aroma active compounds were identified in three samples by combination analyses of gas chromatography‐olfactometry (GC‐O) and odor activity value (OAV). The appearance, smell, texture, and taste of the three different samples had shown different changes, but the sensory characteristics of the SGT were more similar to those of the STF by quantitative descriptive analysis (QDA) and principal component analysis (PCA). This study indicated that the closed system of GSTF could be applied in PXDB fermentation to obtain higher quality products, which brought a bright prospect of replacing the traditional fermentation process to realize the controllable industrialized production of PXDB., The results showed that flavor characteristics of SGT were similar to those of the STF. This study indicated that the closed system of GSTF could be applied in PXDB fermentation to obtain higher quality products, which brought a bright prospect of replacing the traditional fermentation process to realize the controllable industrialized production of PXDB.

A closed system of gradient steady-state temperature field (GSTF) was constructed to ferment Pixian broad bean paste (PBP). The contents of physicochemical factors and organic acids in the fermentation under GSTF (FG) were closer to those in the traditional fermentation (TF). The taste intensities of 8 free amino acids in the FG were higher than those in the constant temperature fermentation (CTF), but 14 in the TF showed the highest among the processes of FG, CTF and TF. The FG product had the most volatiles with 87, and its flavor properties were more stable. The FG produced great effects on the microbe evolutions especially improved the fungal diversity. Bacillus were identified as the core microbes in the FG while the roles of Staphylococcus, Lactobacillus and Pantoea were strengthened. The results indicated that the fermentation characteristics in the FG had been further improved compared with the CTF.

Cilj ovog završnog rada je bio prikazati izračun stacionarne temperature prijenosnog voda. Za izračun se koristio IEEE Std 738 standard. U radu se nalaze sve potrebne jednadžbe za izračun potrebnih podataka. Isto tako u radu se nalazi i objašnjenje varijabli koje se koriste za izračun kao i njihov iznos koji se koristio u izračunu. Za izračun stacionarne temperature je koristila metoda koja je navedena u IEEE Std 738 standardu, odnosno Mullerova metoda iteracije. Pomoću nje su riješena šest slučaja, tri različita voda pri nominalnim strujnim opterećenjem i njihova usporedba, kao i tri voda na različitim opterećenja kako bi se pokazalo kakav struja ima utjecaj na stacionarnu temperaturu voda. Rješenja su prikazana grafički uz iznose stacionarne temperature iznad grafova. The aim of this final paper was to present calculaton of steady-state temperature of contuctor. The IEEE Std 738 was used for the calculation. The paper contains all the necessery equations to calculate the required dana. Also in the paper there is an explanation of the variables that is used for calculation as well as their amount. The method specified in IEEE Std 738 standard is the Muller iteration method, that was used to calculate the steady-state temperature. It solved six cases, three different contuctor at nominal current load, as well as three conductors on three different loads to show inpact of current that has on the steady state temperature of counductor. The solutions is shown graphically with amounts of steady state temperature above the graphs.

This paper deals with the problem of inserting a temperature sensor in the neighbourhood of a chip to monitor the junction temperature. If the sensor is not in the middle of the heat source, the recorded temperature can be quite different from the chip temperature we are mainly interested in. For the steady state temperature, it is rather easy to introduce a correction factor. For the transient behaviour of the temperature, there is a tremendous difference between the chip and the sensor temperature, which cannot be neglected if the temperature is used as a parameter to change, for example, the clock frequency in order to improve the throughput.

To accurately describe the distribution law of the temperature field formed by a single freezing pipe under the action of a seepage field, the shape of the freezing front was simplified using a segmentation-equivalent method. The analytical solution of the steady-state temperature field was derived, and the accuracy was verified using a physical model test. Combined with the results of the model test and the calculation results of the analytical solution, the distribution law of the freezing temperature field formed by a single pipe under different seepage velocities was analyzed. It was found that compared with the no flow rate, when the seepage velocity was 3, 6, and 9 m/day, the frozen area was reduced from 17.97 × 104 mm2 to 15.77 × 104, 3.84 × 104, and 3.05 × 104 mm2, respectively. The proportion of frozen area below −5°C increased from 39.43% to 40.19%, 49.84%, and 51.52%, respectively. The average freezing temperature field reduced from −5.78 to −5.86, −7.31, and −7.50°C, respectively. As the seepage velocity increased, the frozen area formed by a single pipe decreased while the proportion of the low-temperature zone increased and the average temperature of the temperature field decreased.

The rated load temperature rise of an electric machine is an important performance metric that is typically determined by loading the machine at full load. However, it takes several hours to complete as the final temperature of the machine is only known after the machine is thermally stable. It would be desirable to complete such a test in ‘minutes’ instead of several hours. For large machines, it is practically impossible to load the machines at full load, due to lack of dynamometer capacity. It is therefore desirable if such a test could be performed without running the machine at full load. This paper proposes to determine the rated load temperature of a machine in a rapid manner. Two methods are considered: (i) short time overloading of the machine and (ii) a superposition equivalent loading approach that allows for determining the temperature rise of the machine without testing it at full load conditions. The obtained results indicate that these methods can be applied with suggested improvements to determine temperature for both small and large machines.

The main objective of the project is to use a simple numerical technique to find out the temperature distribution in each of the three planes of the block. For many practical problems, nume...

Regarding the high thermal load of piston in engines, a novel apparatus, memory test system (MTS), was designed for steady-state temperature measurement of piston. By heating MTS up to 100 °C and 120 °C respectively, a test was carried out to verify the system and measure its error. Considering poor working conditions in engine, the readings of MTS and thermal plugs were compared with each other through an engine test to confirm the reliability of MTS. Moreover, MTS was used to measure piston temperature under multiple working conditions. The results show that MTS has very high precision and reliability and is competent in multi-condition test. MTS is an effective tool to measure piston temperature.

Taking the forging die of an automobile differential shell as example, the influence of some die forging process parameters and die structure parameters on the die wear was investigated. Based on a modified Archard wear model and the application of finite element method simulation, the die wear depth was calculated under a steady state temperature field. Within the scope of the experimental data, the research shows that: with the increase of billet preheating temperature, the wear is reduced gradually. Improving die preheating temperature, the wear increases gradually. When the forming speed is 300mm/s~400mm/s, the wear value decreases first and then increases.When the forming speed is over than 400mm/s, the change of wear value is not obvious. Increasing flash thickness and round radius, the wear value reduces gradually.

This paper reports abnormal effects of Auger recombination in InGaAs/InAlAs quantum well probed by steady state temperature and excitation-power dependent photoluminescence measurements. The transition from Auger recombination to Shockley–Read–Hall recombination is clearly manifested with rising temperature, and abnormal enhancement of Auger recombination at low temperatures is evidenced. Detailed analysis indicates that such enhancement is positively correlated with strong localization, and can be either relative and due to reduction of Shockley–Read–Hall recombination, or absolute and resulted from the confinement-induced uncertainty of momentum. It suggests that excitation-power dependent photoluminescence measurement is effective to assess the side-effect of the localization, and therefore a convenient evaluation routine of alloy quantum wells.

We show how to use numerical analysis of short-time range experimental data for predicting the limit steady-state value of the investigated parameter. In this article the approach has been applied to a specific, although typical, thermal problem: determining the average steady-state temperature of a heater in the convective and radiative heat exchange with the environment. First, we describe a heat exchange experiment aimed at obtaining temperature experimental data in both short and long time range. Then we present a methodology for applying two methods, i.e., neural networks and least squares approximations, for obtaining predictions about the steady-state temperature values based on short time experimental data. The aim of the study is to compare the predictions to each other and to the long time experimental values, with the aim of determining the applicability range of the two methods.

A finite element analysis is presented about 3D curved non-planar cracks in functionally graded materials (FGMs) subjected to steady state temperature gradients. The interaction energy integral is employed in conjunction with a computational strategy that does not require a priori information about crack front and crack surface curvatures. The influence of graded thermal and mechanical properties on mixed mode stress intensity factors (SIFs) is explored in detail. Results highlighted the robustness of the proposed computational framework, which therefore can be effectively deployed in the analysis of thermal fracture in FGMs containing curved non-planar cracks.

This paper presents a mathematical model of heat transfer in a prevascular breast tumor. The model uses the steady state temperature of the breast at the skin surface to determine whether there is an underlying tumor and if so, verifies whether the tumor is growing or dormant. The model is governed by the Pennes equations and we present numerical simulations for versions of the model in two and three dimensions.

Plastic deformation of the tool is one of the most important wear modes in metal cutting, especially in continuous cutting operations. Since the strength of the tool material depends strongly on the temperature, a correct temperature distribution in the cutting edge is of key importance for the prediction of plastic deformation of the cutting edge.The temperature distribution in coated cemented carbide cutting tools is investigated using experimental techniques (IR-CCD) and finite element analysis. CVD-coated cemented carbide inserts are tested in continuous turning of quenched and tempered steel (AISI 4340). Cutting forces and edge temperature distributions are measured in 2D orthogonal turning. Finite element simulations of orthogonal turning of AISI 4340 steel with CVD coated cemented carbide inserts are performed. The simulation results are used to predict steady state temperature distribution in tool by performing further coupled thermo-mechanical finite element simulations. Different methods of heat source on tool rake face are used.It is observed that steady state temperature distribution from simulation matcheswell with experimental result.

Siemens Energy has a large fleet of aero derivative gas turbines installed in oil & gas and power generation applications globally. Over the past several years, several incidents of disk corrosion damage have been observed during the power turbine overhauls especially for the units fielded in marine environment. Most of the corrosion attack has been observed at disk firtree (blade attachment features), gas washed disk faces and torque transmission features. In all of these cases the mechanism for corrosion has been identified as Low Temperature Hot Corrosion (LTHC) also known as Type-II sulphidation. Siemens has explored a number of potential operating and/or design options e.g. utilization of more corrosion resistant alloys and coatings to mitigate the effects of the corrosive attack on these disks. However, many of these proposals are either intermediate or long term solutions and are addressed more towards new power turbine disks rather than those that are already in service. In the short term, Siemens technical solution has focused on development of proprietary repair processes to effectively remove the corrosion damage and extend the operational life of in-service disks as well as salvage some of the previously scraped disks. This Paper discusses the methodology and findings from the development and characterization of the repair of the power turbine disks when exposed to corrosion and other operational damage.

This paper presents the verification of the relationship between the temperature and the hysteresis loop energy for the CuZn37 brass under multiaxial fatigue loading. Fatigue tests were performed on the hollow specimens subjected to fully reversed tension-compression, torsion, proportional loading, 90° out-of-phase non-proportional loading and two another non-proportional loadings with frequency differences. All test were strain-controlled. Calculations of a plastic strain energy were based on midlife strain hysteresis loops data. The calculated specimen temperatures were compared with temperatures observed by thermographic camera.

In this paper finite elastic and plastic stresses have been investigated using the concept of transition theory with the use of generalized strain measure i.e. nonlinear terms in the displacement are also included which are not included in classical theory. In this paper, we analyze the impact of temperature and pressure on the circular cylinder which is the cause of failure of cylinder. It has been noticed from the results that pressure and temperature play a significant role in the failure of the cylinder. It has been noticed that cylinder made up of the material whose compressibility is at the higher side is best for the designing purpose as compared to cylinder with less compressible material.

In order to develop a thermal model for a generator or a motor, several experiments need to be conducted. One of the challenges in conducting the experiment is that it consumes a lot of time to reach its steady state condition. This is because a generator or a motor has a lot of moving parts and a large amount of surface area causes a very slow rise in temperature. This paper proposes a new method to reduce the experimental time by estimating the settling time using a modeling technique used in the control system engineering. From the data presented, the experimental time can be reduced approximately 55 percent. Furthermore, it is also found that the average steady state temperature for the wire winding is 47.55°C and the predicted temperature from the formulated equation is 47.09°C with error less than 1 percent.

The prime objective of the present numerical study is to obtain relatively more realistic values of performance parameters of a sheet and tube type solar flat plate collector of fixed collector area and number of tubes. Considering temperature dependent thermal conductivity and overall loss coefficient and assuming cubic temperature profile along the tube, pseudo-transient form of two-dimensional, nonlinear partial differential equation governing the steady state temperature distribution in the absorber plate fin is solved using Alternating Direction Implicit finite difference scheme. Numerical results are presented and discussed for wide range of values of aspect ratio of the absorber plate, overall loss parameter, and dimensionless fluid outlet temperature. On the basis of discussion of these results, it is concluded that assumption of constant thermal conductivity and overall loss coefficient results in overestimation of the total entropy generation rate with substantial error. It is also concluded that for any fixed set of values of dimensionless fluid outlet temperature and overall loss parameter, total entropy generation rate increases linearly with increase in aspect ratio of absorber plate. Further, it is found that total entropy generation rate increases with increase in overall loss parameter, the rate of increase being somewhat higher for lower values of overall loss parameter and a decrease in fluid outlet temperature results in an appreciable increase in total entropy generation rate.

Thermal stress and strain rates in a thick walled rotating cylinder under steady state temperature has been derived by using Seth?s transition theory. For elastic-plastic stage, it is seen that with the increase of temperature, the cylinder having smaller radii ratios requires lesser angular velocity to become fully plastic as compared to cylinder having higher radii ratios The circumferential stress becomes larger and larger with the increase in temperature. With increase in thickness ratio stresses must be decrease. For the creep stage, it is seen that circumferential stresses for incompressible materials maximum at the internal surface as compared to compressible material, which increase with the increase in temperature and measure n.

Steady thermal stresses in a rotating disc with shaft ha ving density variation parameter subjected to thermal load have been derived by using Set h's transition theory. Neither the yields criterion nor the associated flow rule is assumed here. Results are depicted graphically. It has been seen that compressible material requir ed higher percentage increased angular speed to become fully-plastic as compare to rotating disc made of incompressible material. Circumferential stresses are maximal at the out er surface of the rotating disc. With the introduction of thermal effect it decreases the value of radial and circumferential stresses at inner and outer surface for fully-plastic state.

Synchronous condenser is a key part of ensuring stable operation of the extra-high voltage AC and DC transmission grid. In order to optimize and ensure the reliable operation of the synchronous condenser cooling system, it is necessary to master the temperature distribution in the synchronous condenser. In the double water internal cooling synchronous condenser, the fluid flow and heat transfer are quite complicated in the water-cooling system of the stator and the rotor. In this paper, the steady-state temperature field of stator coil of TTS-300-2 300MVar double water internal cooling synchronous condenser is calculated by using the finite volume method. The influence of empirical parameters on the calculation results is reduced. The calculation results show that the water temperature and copper temperature increase linearly along the direction of water flow.

The existing analytical formulas to calculate the temperature field distribution of artificial frozen soil walls are all based on the conditions that the surface temperatures of all freezing pipes are equivalent. In this paper, analytical solution of steady state temperature field of two freezing pipes with different temperatures is deduced based on thermal potential superposition method. The correctness of the analytical formulas is verified by comparing the temperature field distributions of the analytical formulas and those of the numerical simulations in the same conditions. And discussions are made to analyze the influence of some parameters on temperature field distribution of this condition.

This study considered the effect of temperature and relative humidity on the performance of softballs, baseballs and bats. The balls were conditioned in constant humidity and temperature environments and then impacted against a rigidly supported load cell from which the ball coefficient of restitution and stiffness were obtained. The balls reached steady state temperature on the order of a few minutes, while steady state humidity required upwards of 2 weeks. Ball stiffness and coefficient of restitution tended to decrease with increasing humidity. Increasing temperature generally caused ball stiffness to decrease and the coefficient of restitution to increase. Balls made from synthetic materials tended to resist the effects of moisture, but showed an increased sensitivity to temperature. The effect of temperature and humidity on bat performance (sign and magnitude) depended on the design of the ball and bat. The largest effect occurred in professional baseball, where for a long fly ball, decreasing the temperature by 33 °C and lowering the relative humidity from 90 to 10 % resulted in a 5 m decrease and a 15 m increase in hit distance, respectively.

Cutaneous melanoma is the most commonly diagnosed cancer and its incidence is on the rise worldwide. Early detection and differentiation of a malignant melanoma from benign cutaneous lesions provides an excellent chance for treating the disease. Thermography is a non-invasive tool that can be used to detect and monitor skin lesions. We model heat transfer in a skin region containing a lesion. The model which is governed by the Pennes equation uses the steady state temperature at the skin surface to determine whether there is an underlying lesion. Numerical simulations from the model ascertain whether the lesion is malignant or benign.

To analyze the steady-state temperature field, a three-factor orthogonal test was taken to study comprehensively how the load, speed and tire pressure can influence the tire temperature. The finite element simulation was carried out according to the uncoupled idea. Based on the single-factor analysis towards the speed factor, the actual convection coefficient of different boundaries was determined to calculate the steady-state temperature field at last. These analyses indicate that the tire temperature rise increase with the factor of load and speed, decrease with the increase of the initial tire pressure. The load has the biggest influence on the tire temperature rise, while the speed has the least. With the combination of steady-state temperature field and heat generation rate distribution, all these high-temperature regions can be explained clearly from the finite element perspective.