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Losses in electric machines produce heat and cause an efficiency drop. As a consequence of heat production, temperature rise will occur which imposes severe problems. Due to the dependence of electrical and mechanical performance on temperature, conducting thermal analysis for a special electric machine that has a compact configuration with poor heat dissipation capability is crucial. This paper aims to carry out the thermal analysis of an axial-field flux-switching permanent magnet (AFFSPM) machine for electric vehicle application. To fulfill this purpose, three-dimensional (3D) finite element analysis is performed to accurately derive electromagnetic losses in active components. Meanwhile, copper losses are calculated by analytic correlation in maximum allowable temperature. To improve thermal performance, cooling blades are inserted on the frame of AFFSPM, and 3D computational fluid dynamics (CFD) is developed to investigate thermal analysis. The effect of different housing materials, the external heat transfer coefficient, and various operating points on the components' temperature has been reported. Finally, 3-D FEA is used to conduct heat flow path and heat generation density. [ABSTRACT FROM AUTHOR]

A hot-stamping method was established for manufacturing high-strength automotive parts with good shape fixability. The hot-stamping method has recently been applied to high-performance parts with tailored properties. CAE is indispensable for the design of such parts. To design hot-stamped parts, the forming simulation must be coupled with thermal analysis to consider the effect of temperature on formability. The final shape does not need to be predicted because of its good fixability. However, for high-performance parts with tailored properties, predicting the effect of phase transformations on the final shape is important. A CAE method that considers the phase transformation effects was developed to predict the final shape of the hot-stamped parts. The accuracy of the final shape calculation utilizing the CAE method is also investigated. Hotstamping experiments were conducted to obtain parts of different shapes via cooling control, and a CAE analysis of the final shape for each experimental condition was conducted. It was clarified that the final shape varied by changing the cooling process and that the results of CAE, including phase transformation, agreed with the tendency for shape change in the cross-section. [ABSTRACT FROM AUTHOR]

Purpose: This paper reported the modeling steps of coupled beam nanocomposite system and its fundamental frequency characteristics. The model has been derived for two straight coupled beams (made of carbon nanotube, CNT) as the continuous transitional springs, including a middle elastic layer. Methods: The effective properties of the beam components are evaluated based on the well-known rule of mixture. Additionally, to achieve the generality of the material distribution, various configurations of CNT have been adopted in the current model through the thickness of the structure. The main objective of the present study is to evaluate the effect of material temperature dependency on the frequency parameter of the nanocomposite double beam system. The structural model has been derived mathematically using the robust lower-order theory (first-order shear deformation, FSDT) to compute the eigenvalues without hampering the degree of solution accuracies. The nanotube properties are also considered to be temperature-dependent (TD). The final eigenvalues are computed via a semi-analytical approach, namely generalized differential quadrature (GDQ) approach. Results: First, the natural frequencies of homogenous beam system are compared with the results of frequency parameter available in the literature. Then, the fundamental frequencies of the coupled beam system have been computed analytically for different structural input parameters (material properties, end constraints of full structure and middle elastic layer) to showcase the effect individual and/or combined conditions with and without the influence of temperature. Conclusion: The final outcomes are revealed in detail for different input parameters and the subsequent outcomes. [ABSTRACT FROM AUTHOR]

The aim of the study was to determine the influence of the amount of a commonly used binder in foundry work, furfuryl resin – on the course of the thermal regeneration of used moulding sand. The thermal regeneration procedure was carried out at a temperature of 525°C, the required temperature determined according to a specific procedure, and a lower and less effective temperature of 400°C. On the basis of the ignition losses, the influence of the regeneration temperature on the effects of the procedures carried out was compared. It was found that 400°C was too low to effectively clean the binder matrix, but that the more resin in the spent sand, the more intense the cleaning effect. When the required regeneration temperature for furfuryl resin of 523°C was used, higher binder degradation kinetics were observed due to the additional energy supplied to the process from the combustion of a large amount of organic material in the moulding sand. [ABSTRACT FROM AUTHOR]

The number of cycles to the end of life for high-power IGBT modules is expressed as a function of the stress parameters in the model. Most of the time, these models are generated on the basis of experimental data from accelerated power-cycling experiments that are done at preset temperatures and stress levels. This paper proposed a systematic Reliability evaluation process for large-scale commercial and utility-level PV power systems. The major contribution of this work is the quantification of the impact of junction temperature on the failure rates of critical components such as PV Inverters and capacitors. Usually, the reliability assessment of the power electronic switch such as IGBT and inverter focused on component level, whereas much fewer cases discussed the Reliability evaluation for the entire PV system. In light of the above concerns, this article discussed the effect of junction temperature on the lifetime of IGBT modules, and the relevant lifetime factor is modelled. This study enables us to include the junction temperature effect on the lifetime model of IGBT modules under the given mission profiles of the converter. [ABSTRACT FROM AUTHOR]

There are cases where the common approaches used to assess the temperature loading effects may not be sufficient, especially in the case of integral abutment bridges (IABs). In IABs, the incorrect choice of the design temperature may result in an unwanted tensional state in the bridge decks and additional loads on the abutments. For post‐tensioned bridges, the combined effects of excessive temperature loads and loss of tension in the post‐tensioned cables due to time‐dependent phenomena like relaxation in steel and shrink‐age and creep in concrete may lead to probabilities of exceedance of serviceability (or ultimate) limit states that exceed the code specifications and/or desired levels of safety, and to cascading negative effects on the operation of the road infrastructure. This research aims at assessing the sensitivity of IABs to the long‐term effects of temperature loads and, in a second step, quantifying the probability of exceedance of relevant serviceability limit states. [ABSTRACT FROM AUTHOR]

Pyropermittivity refers to the effect of temperature on the electric permittivity of a material. It is an emerging thermoanalytical method that is relevant to materials characterization, capacitance-based temperature sensing and thermal energy harvesting. Pyropermittivity is well-known for electrically nonconductive materials, but not conductive materials, which include structural materials (e.g., carbon fibers). This work provides the first determination of the activation energy of permittivity and pyropermittivity-based energy density for any material, and that of the temperature coefficient of permittivity (associated carrier-atom interaction) for conductive materials. Pyropermittivity is discovered in carbon fibers. The permittivity temperature coefficient is positive for uncoated/nickel-coated carbon fibers and polycrystalline graphite of prior work, despite the difference in sign of the temperature coefficient of resistivity between the fibers and graphite. The pyropermittivity is stronger when the fiber is nickel-coated, but is yet stronger for graphite. The coefficient values are all higher than or comparable to those previously reported for nonconductive materials, indicating that nonconductivity does not necessarily enhance pyropermittivity. The activation energy of permittivity is ≤ 40 meV. The pyropermittivity-based volumetric energy density is higher when the carbon fiber is nickel-coated, and is lowest for the graphite. The greater energy density when the carbon fiber is nickel-coated is in line with the greater temperature coefficient of permittivity and the higher permittivity. The low energy density of graphite relates to the low permittivity. The highest energy density obtained is 1.73 × 10–4 J m−3 (nickel-coated carbon fiber for the temperature change of 50 °C); the temperature coefficient of permittivity is 1.37 × 10–3/K for this fiber. [ABSTRACT FROM AUTHOR]

Mechanical and corrosion behavior of high‐strength, high‐zinc (>7 wt%) containing 7068 aluminum alloy is investigated after employing different retrogression and reaging (RRA) treatments. The effect of preaging conditions on the distribution of copper, zinc, and magnesium, the volume fraction of η′ phase, and the width of precipitate free zones (PFZ) have been investigated. Microstructural and compositional features characterized by scanning electron microscope‐energy dispersive spectroscopy, scanning transmission electron microscope, and differential scanning calorimetry are correlated with hardness and corrosion performance. The localized attack is manifested in the dissolution of second phase precipitates which occurs from selective leaching of magnesium and aluminum. A combination of two opposite effects, that is, the presence of nobler, high‐copper grain boundary precipitates and microgalvanic effect of PFZ along with the distribution of alloying elements, that is, Cu, Zn, and Mg govern the electrochemical behavior of RRA‐treated 7068 alloy. Optimum preaging and RRA conditions are identified for this high‐zinc 7xxx series alloy. [ABSTRACT FROM AUTHOR]

This research presents an extension of the SPICE loudspeaker work done by Leach for an overhung-type moving-coil dynamic loudspeaker, where the height of the voice coil is greater than the magnetic gap's height. Using LTspice software, which simulates SPICE, the complete equivalent electrical, mechanical, and acoustic models from the electroacoustic analogies were developed, which allowed verifying the original equivalent model. Sub-circuits were then developed, allowing direct measurement of the velocity and volume velocity emitted by the diaphragm in the complete equivalent mechanical circuit. In addition, three models of electrical inductance and three models of radiation acoustic impedance were implemented. Furthermore, the thermal linear model of the loudspeaker and the resistance model with temperature variation of the voice coil were implemented. The results of the models showed consistency in the measured and simulated responses of the loudspeaker used. The different electrical inductance and radiation acoustic impedance models showed their use and implementation advantages and disadvantages. The thermal linear model showed a reasonable estimation of the measured temperature in the loudspeaker, except for the cooling of the voice coil. Finally, the results of the implementation of the thermal model on the electrical resistance of the loudspeaker showed the expected behavior as indicated in the literature, i.e., increasing the temperature increases the magnitude of the input electrical impedance, decreases the displacement and velocity of the diaphragm and decreases the sound pressure level. [ABSTRACT FROM AUTHOR]

Today, an extensive electrification is occurring in all industrial sectors, with a special interest seen in the automotive and aerospace industries. The electric motor, surely, is one of the main actors in this context, and an ever-increasing effort is spent with the aim of improving its efficiency and torque density. Hairpin windings are one of the recent technologies which are implemented onto the stator of the electric motor. Compared to conventional random windings, it inherently features lower DC resistance, higher fill factor, better thermal performance, improved reliability, and an automated manufacturing process. However, its bottleneck is the high ohmic losses at high-frequency operations due to skin and proximity effects (AC losses), resulting in a negative impact on the temperature map of the machine. Nevertheless, while it is well-known that DC losses increase linearly with the operating temperatures, the AC losses trend needs further insight. This paper demonstrates that operating the machine at higher temperatures could be beneficial for overall efficiency, especially at high-frequency operations. This suggests that a paradigm shift is required for the design of electric motors equipped with hair-pin windings, which should therefore focus on a temperature-oriented approach. In addition, the effect of the rotor topology on AC losses, which is often overlooked, is also considered in this paper. The combination of these effects is used to carry out observations and, eventually, to provide design recommendations. Finite element electromagnetic and thermal evaluations are performed to prove the findings of this research. [ABSTRACT FROM AUTHOR]

With the wide application of motors in deep sea exploration, deep-sea motors require a higher power density and a longer lifetime. Motor lifetime mainly depends on the thermo-mechanical stress (TMS) load on its stator insulation. Unlike normal motors, deep-sea motors are usually filled with oil to compensate for the high pressure generated by seawater, which leads to high additional viscous drag loss. This, combined with the high pressure, will greatly change the TMS distribution and further influence motor insulation lifetime. Thus, the insulation degradation analysis of deep-sea oil-filled (DSOF) motors due to TMS has become important. This paper presents a TMS analytical model of DSOF motor insulation, considering the joint effects of high pressure and motor temperature. The CFD method is adopted to perform motor thermal analysis, considering temperature effects on viscous drag loss. The FEA method is adopted for thermo-mechanical analysis and to verify the analytical model accuracy. Rainflow counting and the Miner fatigue method are adopted to evaluate motor lifetime. Results show that compared with motors working in normal environments, TMS on DSOF motor insulation can be reduced by up to 59.5% due to high pressure and the insulation lifetime can be increased by up to 16.02%. Therefore, this research can provide references for high power density DSOF motor design. [ABSTRACT FROM AUTHOR]

This document is a correction notice for an article titled "The inulin hydrolysis by recombinant exo-inulinases: determination the optimum temperatures and activation energies" published in the Journal of Thermal Analysis & Calorimetry. The correction states that three references and their citations were missing from the original article. The correction provides the correct references and apologizes for the oversight. The publisher, Springer Nature, remains neutral and unbiased in regards to jurisdictional claims and institutional affiliations. [Extracted from the article]

In this article, we propose an efficient methodology for the electrothermal characterization of power amplifier (PA) integrated circuits. The proposed electrothermal analysis method predicts the effect of temperature variations on the key performances of PAs, such as gain and linearity, under realistic dynamic operating conditions. A comprehensive technique for identifying an equivalent compact thermal model (CTM), using data from 3-D finite element method thermal simulation and nonlinear curve fitting algorithms, is described. Two efficient methods for electrothermal analysis applying the developed CTM are reported. The validity of the methods is evaluated using commercially available electrothermal computer-aided design (CAD) tools and through extensive pulsed RF signal measurements of a PA device under test. The measurement results confirm the validity of the proposed electrothermal analysis methods. The proposed methods show significantly faster simulation speed compared with available CAD tools for electrothermal analysis. Moreover, the results reveal the importance of electrothermal characterization in the prediction of the temperature-aware PA dynamic operation. [ABSTRACT FROM AUTHOR]

In this article, an electromagnetic–thermal coupling algorithm based on the discontinuous Galerkin time-domain (DGTD) and spectral-element time-domain (SETD) methods is proposed, which can adopt two independent grids for thermal simulation and electrical simulation, respectively. It employs time-domain solvers for both the electrical and thermal fields. Compared with the conventional cosimulation scheme (e.g., time-domain solvers for the thermal field and frequency-domain solver for the electrical field), it can provide better simulation precision for problems characterized with small size or drastic field changes. By comparing the results of electromagnetic–thermal coupling simulation with the results of electromagnetic simulation, the effect of temperature change on electromagnetic field propagation is analyzed. [ABSTRACT FROM AUTHOR]

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An efficient thermal management system (TMS) of electric vehicles requires a high-fidelity battery model. The model should be able to predict the electro-thermal behavior of the battery, considering the operating conditions throughout the battery’s lifespan. In addition, the model should be easy to handle for the online monitoring and control of the TMS. Equivalent circuit models (ECMs) are widely used because of their simplicity and suitable performance. In this paper, the electro-thermal behavior of a prismatic 50 Ah LMO/Graphite cell is investigated. A dynamic model is adopted to describe the battery voltage, current, and heat generation. The battery model parameters are identified for a single cell, considering their evolution versus the state of charge and temperature. The needed experimental data are issued from the measurements carried out, thanks to a special custom electrical bench able to impose a predefined current evolution or driving cycles, controllable by serial interface. The proposed battery parameters, functions of state of charge (SOC), and temperature (T) constitute a set of interesting and complete data, not available in the literature, and suitable for further investigations. The thermal behavior and the dynamic models are validated using the New European Driving Cycle (NEDC), with a large operating time, higher than 3 h. The measurement and model prediction exhibit a temperature difference less than 1.2 ◦C and a voltage deviation less than 3%, showing that the proposed model accurately predicts current, voltage, and temperature. The combined effects of temperature and SOC provides a more efficient modeling of the cell behavior. Nevertheless, the simplified model with only temperature dependency remains acceptable. Hence, the present modeling constitutes a confident prediction and a real step for an online control of the complete thermal management of electrical vehicles. [ABSTRACT FROM AUTHOR]

Semiclassical approximations to response functions can allow the calculation of linear and nonlinear spectroscopic observables from classical dynamics. Evaluating a canonical response function requires the related tasks of determining thermal weights for initial states and computing the dynamics of these states. A class of approximations for vibrational response functions employs classical trajectories at quantized values of action variables and represents the effects of the radiation-matter interaction by discontinuous transitions. Here, we evaluate choices for a thermal weight function which are consistent with this dynamical approximation. Weight functions associated with different semiclassical approximations are compared, and two forms are constructed which yield the correct linear response function for a harmonic potential at any temperature and are also correct for anharmonic potentials in the classical mechanical limit of high temperature. Approximations to the vibrational linear response function with quantized classical trajectories and proposed thermal weight functions are assessed for ensembles of one-dimensional anharmonic oscillators. This approach is shown to perform well for an anharmonic potential that is not locally harmonic over a temperature range encompassing the quantum limit of a two-level system and the limit of classical dynamics. [ABSTRACT FROM AUTHOR]

Cubic ice is said to have stacking disorder when the H2O sequences in its structure (space group Fd3m) are interlaced with hexagonal ice (space group P63/mmc) sequences, known as stacking faults. Diffraction methods have shown that the extent of this disorder varies in samples made by different methods, thermal history, and the temperature T, but other physical properties of cubic and hexagonal ices barely differ. We had found that at 160 K, the thermal conductivity, κ, of cubic ice is ~20% less than that of hexagonal ice, and this difference varies for cubic ice samples prepared by different methods and/or subjected to different thermal history. After reviewing the methods of forming cubic ice, we report an investigation of the effects of stacking disorder and other features by using new data, and by analyzing our previous data on the dependence of κ on T and on the pressure. We conclude that the lower κ of cubic ice and its weaker T-dependence is due mainly to stacking disorder and small crystal sizes. On in situ heating at 20-50 MPa pressure, κ increases and cubic ice irreversibly transforms more sharply to ice Ih, and at a higher T of ~220 K, than it does in ex situ studies. Cooling and heating between 115 and 130 K at 0.1 K min-1 rate yield the same κ value, indicating that the state of cubic ice in these conditions does not change with time and T. The increase in κ of cubic ice observed on heat-annealing before its conversion to hexagonal ice is attributed to the loss of stacking faults and other types of disorders, and to grain growth. After discussing the consequences of our findings on other properties, we suggest that detailed studies of variation of a given property of cubic ice with the fraction of stacking faults in its structure may reveal more about the effect of this disorder. A similar disorder may occur in the mono-layers of H2O adsorbed on a substrate, in bulk materials comprised of two dimensional layers, in diamond and in Zirconium and in numerous other crystals. [ABSTRACT FROM AUTHOR]

Annealed importance sampling is a simulation method devised by Neal [Stat. Comput. 11, 125 (2001)] to assign weights to configurations generated by simulated annealing trajectories. In particular, the equilibrium average of a generic physical quantity can be computed by a weighted average exploiting weights and estimates of this quantity associated to the final configurations of the annealed trajectories. Here, we review annealed importance sampling from the perspective of nonequilibrium path-ensemble averages [G. E. Crooks, Phys. Rev. E 61, 2361 (2000)]. The equivalence of Neal's and Crooks' treatments highlights the generality of the method, which goes beyond the mere thermal-based protocols. Furthermore, we show that a temperature schedule based on a constant cooling rate outperforms stepwise cooling schedules and that, for a given elapsed computer time, performances of annealed importance sampling are, in general, improved by increasing the number of intermediate temperatures. [ABSTRACT FROM AUTHOR]

The strict tolerance space of three-dimensional (3D) crystalline structures is still a significant challenge in the area of switching dielectrics in comparison with lower-dimensional structures. Generally, the function of crystalline materials can be given or adjusted by controlling the environment in which synthesis takes place or the packing rearrangement. Using this method, special functional enhancements or changes in the dielectrics can be realized by improving the synthetic strategies. Here, a 3D switchable dielectric compound [MeHdabco]K(BF4)3 was achieved by employing the temperature selective effect. In particular, its structure is completely different from the usual 3D perovskite structure, which is constructed using two different cation-template frameworks. Moreover, the 3D [MeHdabco]K(BF4)3 shows a structural phase transition at 358 K. The thermal analysis (differential scanning calorimetry (DSC)) and X-ray diffractometry results provided evidence of these phase changes. This work provides a feasible strategy that can be used to achieve the different structures of an 'isomer', and enrich the method used for designing diverse functional materials. [ABSTRACT FROM AUTHOR]

The classical approach for the thermal analysis of solids and fluids uses the strain additive decomposition to account for the effect of the temperature. This strain-based approach does not properly capture the effect of complex stress-free reference-configuration geometry, is applicable only to small deformation problems, and leads to simplified expression for the Green–Lagrange strain tensor. In view of the geometric description of the absolute nodal coordinate formulation (ANCF), a new ANCF gradient-based approach is proposed. This approach employs a multiplicative decomposition of the matrix of position-gradient vectors in the stress-free reference configuration into two position-gradient matrices. One matrix is associated with the reference-configuration geometry before the application of the thermal load, and the other accounts for the volumetric change due to the change in temperature. A numerical study demonstrated the implementation of the proposed gradient-based approach. [ABSTRACT FROM AUTHOR]

In this paper, Finite element thermal analysis has been performed on a gas turbine afterburner jet pipe liner. Burnt air and fuel mixture from the main fuel system and afterburner system flows through the liner before exiting into the atmosphere via nozzle experiences a high variation of temperature across it thorough the engine operation thus susceptible to failure due to thermal stress. Simulations were done considering conduction and convection only. The FE (Finite element) model is first studied under steady-state conditions with constant loading. The analysis is extended to transient boundary conditions which are common in practical afterburner jet pipe liners to investigate the effect of temperature. Each of the parameters had a marked effect on jet pipe liner performance within the range of conditions investigated. The research work has been carried out at Heat Transfer Group, Gas Turbine Research Establishment, DRDO Bengaluru, Karnataka, India. [ABSTRACT FROM AUTHOR]

The structural steel elements of buildings are normally not subjected to full design strength, under normal operation. Structural steel is a non-combustible material and its properties can be affected by elevated temperatures. The terrorist attack on multi-storey steel structure World Trade Centre in New York is worst event in the history, which resulted in tragic loss of lives. Therefore, high rise steel buildings must be able to resist high temperatures so that there is a minimum damage to the structure. The main purpose of this paper is to investigate the temperature effects on multi-storey steel building subjected to elevated temperature. In this paper, a study is made to investigate the effect of elevated temperature on structural elements of steel buildings. The main properties of steel that were found to change with an increase in temperature from 20 degree centigrade to 1400 0C are modulus of elasticity of steel, and yield strength of the structural steel. High grade steel, Fe410 was found to better resist the temperature changes as compared to Fe250. These results are expected to help the designers and planners in making appropriate provisions for providing a higher temperature resistance to the steel structures. [ABSTRACT FROM AUTHOR]

Nano calcium silicate modified by copper oxide (CSC) has been prepared as a new sorbent material. The prepared nano sorbent was characterized by applied different analytical techniques as FTIR and SEM as well as thermal analysis (TG/DSC). The Adsorption process for cesium and cobalt ions was executed considering notable parameters such as effect of initial pH, impact of shaking time as well as initial concentration of each ion, and finally the effect of temperature. The obtained results have been revealing that the adsorption process of the studied ions was remarkably get better using CSC. The monolayer capacities of CSC for Cs(I) and Co(II) in binary system were 83.67 and 103.18 mg/g respectively. The kinetic studies exposed that the adsorption process followed nonlinear pseudo-first-order model. The isothermal studies show that the extended Langmuir model is more applicable than Freundlich model for binary system adsorption process. The maximum value of desorption for the Co (II) and Cs(I) is 97.5% and 73.5 utilized 0.1 M of nitric acid. This indicated that CSC can be regenerated and reused for further adsorption of Co (II) and Cs(I) from wastewater. [Display omitted] • Synthesis of Nano calcium silicate modified by copper oxide (CSC). • Isotherm and surface characterization of prepared material. • Cs+ and Co2+ removal from aqueous solution. • Study of adsorption mechanism. [ABSTRACT FROM AUTHOR]

There is no lubrication in the contact area, which leads to a significant influence of the thermal characteristics on the friction dynamics and life of the helicopter intermediate reducer because the helicopter experiences severe loss of lubrication. In this study, for evaluating the non-linear friction dynamics and transient thermal network models of the intermediate gearbox, a multi-time scale coupling method was proposed to establish a proportional allocation method between the oil film region and the rough peak contact region of the tooth surface by considering the effect of temperature and to study the adsorption film under the condition of severe lubrication loss. The coupled thermal and kinetic characteristics of the severe lubrication loss condition were obtained by calculating the friction coefficients in the lubricated and dry-friction regions. The results showed that the friction coefficient of the bevel gear tooth surface fluctuated between 0.1 and 0.6, and the degree of the gear axis trajectory shift was more evident owing to the increase in the friction force excitation caused by the increase in the friction coefficient. [ABSTRACT FROM AUTHOR]

The conformational order in Ca-arachidate Langmuir-Blodgett films on solid glass supports is investigated by means of vibrational sum-frequency generation spectroscopy (VSFG). The symmetric C-H stretching vibrations of both the terminal methyl and the methylene groups are utilized to monitor the chain conformation at various sample temperatures under ambient conditions. At room temperature the film is well-ordered consisting almost entirely of all-trans configured chains. Between 340 and 430 K we observe a marked increase in gauche-defects before oxidative degeneration starts at sample temperatures above 470 K. The temperature dependence of the data is well represented by apparent enthalpy changes for the formation of gauche-defects, sharply increasing with packing density from 29 to 62 kJ/mol; values, which are an order of magnitude larger than those of the gas phase molecule. These large apparent enthalpies do not prevent the formation of a high degree of conformational disorder at elevated temperatures. [ABSTRACT FROM AUTHOR]

Simulations are performed of a small quantum system interacting with a quantum environment. The system consists of various initial states of two harmonic oscillators coupled to give normal modes. The environment is 'designed' by its level pattern to have a thermodynamic temperature. A random coupling causes the system and environment to become entangled in the course of time evolution. The approach to a Boltzmann distribution is observed, and effective fitted temperatures close to the designed temperature are obtained. All initial pure states of the system are driven to equilibrium at very similar rates, with quick loss of memory of the initial state. The time evolution of the von Neumann entropy is calculated as a measure of equilibration and of quantum coherence. It is pointed out using spatial density distribution plots that quantum interference is eliminated only with maximal entropy, which corresponds thermally to infinite temperature. Implications of our results for the notion of 'classicalizing' behavior in the approach to thermal equilibrium are briefly considered. [ABSTRACT FROM AUTHOR]

The curved beam bridge exhibits lateral displacement during construction and operation. Taking a curved beam bridge as an example, the status of lateral displacement of the bridge is investigated in detail in this paper. To understand the mechanism of the curved beam lateral displacement, further to determine the curved beam lateral displacement under temperature effect, using ANSYS software to establish solid element model of the curved beam, steady state thermal analysis method is applied to analyze temperature field. Based on the analysis, the lateral displacement under temperature effect is analyzed. Then in order to further explain the lateral displacement mechanism, to discuss the frictional force causing the residual deformation of the rubber bearing to make the lateral displacement of the curved beam, the mechanical mechanism of curved beam under temperature effect is approximately analyzed. On the basis of clarifying the mechanism of lateral displacement, the paper puts forward the reinforcement measures for the curved beam bridge. In order to verify the treatment effect, long-term displacement monitoring is performed on the bridge. Numerical studies and monitoring data show that temperature is the main factor that causes the lateral displacement. Monitoring data over the past year shows that the displacement of the bearing is less than the value of allowable displacement after the reinforcement measures are adopted, and the bridge is in a safe state. [ABSTRACT FROM AUTHOR]

This paper aims at exploring the possibility of using a great percentage of recycled materials into vitreous china (VC), thus, contributing to urban waste decrease while lowering the industry's buying costs, previously optimized, for the sanitaryware production. The recycled blend was introduced in the ceramic slip, Sanitser VC, and used in three sanitaryware production plants. This slip let to improve the environmental performances of the overall ceramic production through energy-saving and a decrease in greenhouse gas emissions. In fact, the firing temperature is 80-100 °C lower than traditional production. Therefore, the objective of this paper was to evaluate the firing behavior, technological properties, and microstructure of a typical industrial vitreous china body in comparison with Sanitser VC. The analytical results confirmed the force of this idea and highlighted the advantages of the choice made. [ABSTRACT FROM AUTHOR]

Molecular dynamics simulations were performed to study the thermal properties of a supercooled liquid near the glass transition regime and of glasses in a one-component soft-core system with the pair potential φn(r) = &eh;(σ/r)n, in which n = 12. The results are examined along a phase diagram, in which the compressibility factor defined by P(ρ*)≡PV/NkBT is plotted against the reduced density ρ* = ρ(&eh;/kBT)3/n (or the reduced temperature T* = ρ*-n/3). Similarly, a time-dependent dynamical compressibility factor can be plotted against the time-dependent reduced density ρt*=ρ(&eh;/kBTt*)3/n (or the reduced time-dependent temperature). Analytical expressions of the specific heats CV and CP and of the entropy, S, were obtained as a function of P(ρ*) or of the scaled potential U*. Even for a rapid cooling process, the CV values are found to be affected by non-equilibrium relaxations in the ρ0*>1.3 region, where ρ0* is the given initial value of ρt*. The problem of the Kauzmann paradox is discussed using these expressions. The fluctuation of the time-dependent temperature, Tt*, which determines CV, is characterized by the spectra that are obtained by multitaper methods. The thermal fluctuation along the non-equilibrium relaxation under NVE conditions was also examined. [ABSTRACT FROM AUTHOR]

The work presented in this paper concerns the study of the thermal behavior due to copper losses and iron losses of a switched reluctance machine with double salience (SRM6/4) by analytical coupling -- 2D finite elements. Calculation by analytical methods of the conduction coefficients in the radial and axial direction as well as the convection coefficients in the air gap of this machine are presented. The values of these found coefficients are used to solve the transient thermal problem for this device using the ADEMEF2D software. The obtained results show a very large increase in temperature at the winding. Heat conduction in both radial and axial directions has a very large effect on the temperature value in all regions of the SRM6/4. [ABSTRACT FROM AUTHOR]

Nanocrystalline zinc oxide (ZnO) photocatalyst has been synthesized by a simple solution combustion method using zinc nitrate as the oxidizer and urea as the fuel. Effect of fuel to oxidizer ratio and ignition temperature on the mechanism of combustion synthesis, crystallinity, morphology, surface area, and optical properties were investigated by thermal analysis, X-ray diffraction (XRD), Scanning electron microscopy (SEM), Diffuse reflectance UV–Visible spectra and Photoluminescence analyses. Photocatalytic activity of the synthesized materials was evaluated by degrading an azo dye at ambient temperature and solution pH. The prepared photocatalysts at the fuel-rich condition possess small crystallite size and more surface area; consequently, a higher photocatalytic dye degradation capability.The powder samples synthesized at the fuel-oxidant ratio of 1.8 and the ignition temperature at 400 °C have shown the maximum percentage (99%) of dye degradation in 180 min. The pseudo-first order photocatalytic dye degradation rate constant of a catalyst sample synthesized at the fuel-oxidant ratio of 1.8 was 0.0253 min−1and it is 3.14 and 2.88 times higher than that of samples synthesized at fuel-oxidant ratios of 0.6 and 1.The outcomes of the present article help to design more pronounced experiments for the synthesis of photocatalysts by varying ignition temperatures and fuel amounts. Image 1 [ABSTRACT FROM AUTHOR]

As the core components of mechanical power system, triple-phase asynchronous motor and reducer are required strictly for temperature control. In this paper, the triple-phase asynchronous motor and the reducer are regarded as a coupling system, and thermal network method is used to predict the temperature field distribution of the coupling system. The predicted temperature of the thermal network method is consistent with the experimental result and the finite-element analysis. Furthermore, analysis shows that motor output power, coefficient of friction between teeth and lubricating oil parameters have a great effect on reducing the temperature of the coupling system. [ABSTRACT FROM AUTHOR]

Superconducting radio frequency (SRF) cavities are often limited by thermal quench, which is an excessive electromagnetic heating that occurs in the high magnetic field area and expands thereafter forcing the cavity to lose its superconducting state. In this article, we demonstrate how the quench phenomena can be modeled using a coupled electromagnetic thermal analysis. The proposed model takes into account the nonlinearity of the material properties at cryogenic temperature and the effect of Kapitza resistance. The proposed approach is used to compute the thermal quench field of a 3.9-GHz 9-cell accelerating cavity, a 2.815-GHz deflecting cavity, and a 1.3-GHz 9-cell accelerating cavity. The computed values of quench field are in good agreement with the measured ones observed during vertical testing at 2 K. Without loss of generality, the proposed methodology can be applied to other cavity geometries. [ABSTRACT FROM AUTHOR]

CaO-Al 2 O 3 -SiO 2 (CAS) glass ceramics were designed and prepared using a melt-quench approach. The coefficient of the thermal expansion (CTE) of the synthesized CAS (4.12 × 10−6 K−1) matched perfectly with that of the SiC ceramic (4.01 × 10−6 K−1). Thermal analysis of the CAS was conducted. Then the joining of the SiC ceramics by the CAS glass ceramics under various process parameters were conducted. The bonding temperature affects the fluidity of the CAS glass and the oxidation of the SiC substrate. The holding duration decides the infiltration of the CAS glass into the SiC substrate. The optimal bonding parameter is 1400 ℃/10 min and the corresponding highest shear strength of the SiC/CAS/SiC bonded joints in average was 56 MPa. Fracture observation was also conducted to help analyze the relationship between the interfacial microstructure and the joint strength. Finally, the formation mechanism of the SiC/CAS/SiC bonded joints was proposed. [ABSTRACT FROM AUTHOR]

Effusive molecular beam measurements of angle-resolved thermal dissociative sticking coefficients for CH4 impinging on a Pt(111) surface, at a temperature of 700 K, are reported and compared to theoretical predictions. The reactivity falls off steeply as the molecular angle of incidence increases away from the surface normal. Successful modeling of the thermal dissociative sticking behavior, consistent with existent CH4 supersonic molecular beam experiments involving rotationally cold molecules, required that rotation be treated as a spectator degree of freedom. [ABSTRACT FROM AUTHOR]

In this communication, we discuss the phenomenon of attainable superheat of liquid and the peculiarities of its release by spontaneous boiling-up. We have combined the apparatus for superheating, namely, bubble chamber, with a high speed micro-optical method for detailed monitoring of the initial stage of boiling-up. In experiments on the isothermal pressure drop, it was found that the boiling-up onset of n-hexane is accompanied by characteristic step signal. The signal has proved to be typical of the heterogeneous character of boiling-up onset in a whole range of superheating degrees. The performance of the method for investigation of the refractive index and density for superheated liquids as functions of temperature and pressure has been revealed. The experimental error is estimated to be 0.1%. [ABSTRACT FROM AUTHOR]

Chemical and thermal denaturation methods have been widely used to investigate folding processes of proteins in vitro. However, a molecular understanding of the relationship between these two perturbation methods is lacking. Here, we combined computational and experimental approaches to investigate denaturing effects on three structurally different proteins. We derived a linear relationship between thermal denaturation at temperature Tb and chemical denaturation at another temperature Tu using the stability change of a protein (ΔG). For this, we related the dependence of ΔG on temperature, in the Gibbs-Helmholtz equation, to that of ΔG on urea concentration in the linear extrapolation method, assuming that there is a temperature pair from the urea (Tu) and the aqueous (Tb) ensembles that produces the same protein structures. We tested this relationship on apoazurin, cytochrome c, and apoflavodoxin using coarse-grained molecular simulations. We found a linear correlation between the temperature for a particular structural ensemble in the absence of urea, Tb, and the temperature of the same structural ensemble at a specific urea concentration, Tu. The in silico results agreed with in vitro far-UV circular dichroism data on apoazurin and cytochrome c. We conclude that chemical and thermal unfolding processes correlate in terms of thermodynamics and structural ensembles at most conditions; however, deviations were found at high concentrations of denaturant. [ABSTRACT FROM AUTHOR]

Cellulosic biomass has the potential to serve as a major renewable energy source. However, its strong recalcitrance to degradation hampers its large-scale use in biofuel production. To overcome this problem, a detailed understanding of the origins of the recalcitrance is required. One main biophysical phenomenon leading to the recalcitrance is the high structural ordering of natural cellulose fibrils, that arises largely from an extensive hydrogen-bond network between and within cellulose polymers. Here, we present a lattice-based model of cellulose Iα, one of the two major natural forms, at the resolution of explicit hydrogen bonds. The partition function and thermodynamic properties are evaluated using the transfer matrix method. Two competing hydrogen-bond patterns are found. This plasticity of the hydrogen-bond network leads to an entropic contribution stabilizing the crystalline fibril at intermediate temperatures. At these temperatures, an enhanced probability of bonding between the individual cellulose chains gives rise to increased resistance of the entire cellulose fibril to degradation, before the final disassembly temperature is reached. The results are consistent with the available crystallographic and IR spectroscopic experiments on the thermostability of cellulose Iα. [ABSTRACT FROM AUTHOR]

A novel optical method has been developed for the measurement of thermal accommodation coefficients in the temperature-jump regime. The temperature dependence of the resonant frequency of a fused-silica microresonator's whispering-gallery mode is used to measure the rate at which the microresonator comes into thermal equilibrium with the ambient gas. The thermal relaxation time is related to the thermal conductivity of the gas under some simplifying assumptions and measuring this time as a function of gas pressure determines the thermal accommodation coefficient. Using a low-power tunable diode laser of wavelength around 1570 nm to probe a microsphere's whispering-gallery mode through tapered-fiber coupling, we have measured the accommodation coefficients of air, helium, and nitrogen on fused silica at room temperature. In addition, by applying thin-film coatings to the microsphere's surface, we have demonstrated that accommodation coefficients can be measured for various gases on a wide range of modified surfaces using this method. [ABSTRACT FROM AUTHOR]

We have used a heated 2 cm × 1 mm SiC microtubular (μtubular) reactor to decompose acetaldehyde: CH3CHO + Δ → products. Thermal decomposition is followed at pressures of 75-150 Torr and at temperatures up to 1675 K, conditions that correspond to residence times of roughly 50-100 μs in the μtubular reactor. The acetaldehyde decomposition products are identified by two independent techniques: vacuum ultraviolet photoionization mass spectroscopy (PIMS) and infrared (IR) absorption spectroscopy after isolation in a cryogenic matrix. Besides CH3CHO, we have studied three isotopologues, CH3CDO, CD3CHO, and CD3CDO. We have identified the thermal decomposition products CH3 (PIMS), CO (IR, PIMS), H (PIMS), H2 (PIMS), CH2CO (IR, PIMS), CH2=CHOH (IR, PIMS), H2O (IR, PIMS), and HC≡CH (IR, PIMS). Plausible evidence has been found to support the idea that there are at least three different thermal decomposition pathways for CH3CHO; namely, radical decomposition: CH3CHO + Δ → CH3 + [HCO] → CH3 + H + CO; elimination: CH3CHO + Δ → H2 + CH2=C=O; isomerization/elimination: CH3CHO + Δ → [CH2=CH-OH] → HC≡CH + H2O. An interesting result is that both PIMS and IR spectroscopy show compelling evidence for the participation of vinylidene, CH2=C:, as an intermediate in the decomposition of vinyl alcohol: CH2=CH-OH + Δ → [CH2=C:] + H2O → HC≡CH + H2O. [ABSTRACT FROM AUTHOR]

A new method, here called thermal Gaussian molecular dynamics (TGMD), for simulating the dynamics of quantum many-body systems has recently been introduced [I. Georgescu and V. A. Mandelshtam, Phys. Rev. B 82, 094305 (2010)]. As in the centroid molecular dynamics (CMD), in TGMD the N-body quantum system is mapped to an N-body classical system. The associated both effective Hamiltonian and effective force are computed within the variational Gaussian wave-packet approximation. The TGMD is exact for the high-temperature limit, accurate for short times, and preserves the quantum canonical distribution. For a harmonic potential and any form of operator A⁁, it provides exact time correlation functions CAB(t) at least for the case of B⁁, a linear combination of the position, x⁁, and momentum, p⁁, operators. While conceptually similar to CMD and other quantum molecular dynamics approaches, the great advantage of TGMD is its computational efficiency. We introduce the many-body implementation and demonstrate it on the benchmark problem of calculating the velocity time auto-correlation function for liquid para-hydrogen, using a system of up to N = 2592 particles. [ABSTRACT FROM AUTHOR]

By measuring the dependences of the temperature-dependent primary ('alpha') dielectric relaxation time behavior on the temperature scanning rate for the glass-forming glycerol, we study the scaling of hysteresis at the glass transition in glycerol. Based on the Vogel-Fulcher-Tammann (VFT) expression and the Angell's fragility concept, notable correlations of the systematic kinetic fragility, and of the hysteresis effect in the vitrification/fusion 'alpha'-relaxation process of glycerol, with the temperature scanning rate, were reasonably analyzed and discussed. It was observed that the kinetic fragility m and the apparent glass-transition temperature hysteresis width ΔTga, respectively, scaled the temperature scanning rate q as m ≈ αmq-γ and ΔTga ≈ A0 + αqβ, at which the exponents, γ and β, were suggested to be characteristic of the resistance to the structure change or fragility change of the system during the glass transition. The observed scaling laws are quite similar to the scaling power law for the thermal hysteresis in the first-order phase transition (FOPT) of solids, providing a significant insight into the hysteresis effect in the glass transition of the glass-forming liquids. [ABSTRACT FROM AUTHOR]

We have studied the separation of a double stranded DNA (dsDNA), which is driven by either the temperature or force. By monitoring the probability of opening of entire base pairs along the chain, we show that the opening of a dsDNA depends not only on the sequence but also on the constraints on the chain in the experimental setups. Our results clearly demonstrate that the force-induced melting of dsDNA, whose one of the ends is constrained, is significantly different from the thermal melting, when both ends are free. [ABSTRACT FROM AUTHOR]