Effect Of Temperature Rise Research Articles

Characterization and Modeling of Hot Deformation Behavior of a Copper-Bearing High-Strength Low-Carbon Steel Microalloyed with Nb

This study investigates hot deformation behavior of a newly developed Cu-bearing high-strength low-carbon steel microalloyed with Nb (Nb-HSLC). A computational method based on experimental data was employed to design the chemical composition of the alloy. Compression tests were carried out in the temperature range of 850-1100 °C as well as strain rates of 0.001-10 s−1 using BAHR Dil 805 A/D thermo-analyzer equipment. The Arrhenius-type constitutive equations were used to model the hot working behavior of the designed steel. Effects of friction and temperature rise during deformation were corrected to obtain the actual stresses. The results showed that the peak flow stress was increased with increasing Zener–Hollomon parameter. The obtained flow curves at strain rates lower than 0.1 s−1 and temperatures above 950 °C represented the typical dynamic recrystallization (DRX) behavior, while the flow curves at temperatures lower than 950 °C at all strain rates were associated with continuous strain hardening. This feature is in good agreement with the precipitation temperature range of Nb(C, N) particles, i.e., 800-1000 °C. Moreover, the flow curves showed the serrations during hot deformation at strain rates of 0.001 and 0.01 s−1, indicating that the dynamic strain aging (DSA) phenomenon occurred at low strain rates. The best fit between “peak stress” and “deformation conditions” was obtained by a hyperbolic sine-type equation (R2 = 0.993). Therefore, the average activation energy was determined as 348 kJ mol−1. The agreement between the achieved model and experimental flow data was verified using the results of additional tests at a strain rate of 5 s−1. The maximum difference between the measured and predicted “peak stresses” was calculated as 5 Mpa.

A Modified Johnson–Cook Model for Dynamic Response of Metals with an Explicit Strain- and Strain-Rate-Dependent Adiabatic Thermosoftening Effect

Metallic alloys are extensively utilized in applications where extreme loading and environmental conditions occur and engineering reliability of components or structures made of such materials is a significant concern in applications. Adiabatic heating in these materials during high-rate deformation is of great interest to analysts, experimentalists, and modelers due to a reduction in strength that is produced. Capturing the thermosoftening caused by adiabatic heating is critical in material model development to precisely predict the dynamic response of materials and structures at high rates of loading. In addition to strain rate effect, the Johnson–Cook (JC) model includes a term to describe the effect of either environmental or adiabatic temperature rise. The standard expression of the JC model requires quantitative knowledge of temperature rise, but it can be challenging to obtain in situ temperature measurements, especially in dynamic experiments. The temperature rise can be calculated from plastic work with a predetermined Taylor-Quinney (TQ) coefficient. However, the TQ coefficient is difficult to determine since it may be strain and strain-rate dependent. In this study, we modified the JC model with a power-law strain rate effect and an explicit form of strain- and strain-rate-dependent thermosoftening due to adiabatic temperature rise to describe the strain-rate-dependent tensile stress–strain response, prior to the onset of necking, for 304L stainless steel, A572, and 4140 steels. The modified JC model was also used to describe the true stress–strain response during necking for A572 and 4140 steels at various strain rates. The results predicted with the modified JC model agreed with the tensile experimental data reasonably well.

Aerothermoelastic analysis of imperfect FG cylindrical shells in supersonic flow

The supersonic panel flutter of functionally graded cylindrical shells under thermal loadings is investigated by considering the effects of various axisymmetric and asymmetric geometric imperfections. The problem is formulated using a nonlinear first-order shear deformation theory of shells with the first-order aerodynamic piston theory. The temperature is assumed to vary in the thickness direction according to the steady-state heat conduction equation. The semi-analytical finite element method (FEM), based on the field consistency redistribution approach is used to obtain discretized nonlinear aeroelastic equations. In the process of FEM, the imperfection functions are also discretized and efficiently approximated by the Hermitian polynomials in order to facilitate the required integrations. For analysis purpose, the deformations and stresses induced by the temperature rise are first computed by solving the nonlinear static aerothermoelastic equations using the Newton-Raphson method. The pseudo-arclength continuation method is also employed to detect the possible snap-through of the shell. The linearized stability equation about the equilibrium state is then used for determining the flutter boundaries. Numerous parametric studies are conducted to examine the effects of temperature rise and imperfections on the flutter boundaries, which show considerable effects of imperfections on changing the trend of variation of the flutter pressure with temperature.

Geometrically Nonlinear Analysis of Functionally Graded Timoshenko Curved Beams with Variable Curvatures

In this paper, geometrically nonlinear analysis of functionally graded curved beams with variable curvatures based on Timoshenko beam theory is presented. Considering the axial extension and the transversal shear deformation, geometrically nonlinear governing equations for the FGM curved beams with variable curvatures subjected to thermal and mechanical loads are formulated. Material properties of the curved beams are assumed to vary arbitrarily in the thickness direction and be independent on the temperature change. By using the numerical shooting method to solve the coupled ordinary differential equations, the nonlinear response of static thermal bending of a FGM semielliptic beams subjected to transversely nonuniform temperature rise is obtained numerically. The effects of material gradient, shear deformation, and temperature rise on the response of the curved beam are discussed in detail. Nonlinear bending of a closed FGM elliptic structure subjected to two pinching concentrated loads is also analyzed. This paper presents some equilibrium paths and configurations of the elliptic curved beam for different pinching concentrated loads.

Climate change and crop farming in Bangladesh: an analysis of economic impacts

Purpose Changes in climate may have both beneficial and harmful effects on crop yields. However, the effects will be more in countries whose economy depends on agriculture. This study aims to measure the economic impacts of climate change on crop farming in Bangladesh. Design/methodology/approach A Ricardian model was used to estimate the relationship between net crop income and climate variables. Historical climate data and farm household level data from all climatic zones of Bangladesh were collected for this purpose. A regression model was then developed of net crop income per hectare against long-term climate, household and farm variables. Marginal impacts of climate change and potential future impacts of projected climate scenarios on net crop incomes were also estimated. Findings The results revealed that net crop income in Bangladesh is sensitive to climate, particularly to seasonal temperature. A positive effect of temperature rise on net crop income was observed for the farms located in the areas having sufficient irrigation facilities. Estimated marginal impact suggests that 1 mm/month increase in rainfall and 10°C increase in temperature will lead to about US$4-15 increase in net crop income per hectare in Bangladesh. However, there will be significant seasonal and spatial variations in the impacts. The assessment of future impacts under climate change scenarios projected by Global Circulation Models indicated an increase in net crop income from US$25-84 per hectare in the country. Research limitations/implications The findings of this study indicate the need for development practitioners and policy planners to consider both the beneficial and harmful effects of climate change across different climatic zones while designing and implementing the adaptation policies in the country. Originality/value Literature survey of the Web of Science, Science Direct and Google Scholar indicates that this study is the first attempt to measure the economic impacts of climate change on overall crop farming sector in Bangladesh using an econometric model.

Effect of wave shaper on reactive materials jet formation and its penetration performance

Abstract Wave shaper effect on formation behavior and penetration performance of reactive liner shaped charge (RLSC) are investigated by experiments and simulations. The reactive materials liner with a density of 2.3 g/cm3 is fabricated by cold pressing at a pressure of 300 MPa and sintering at a temperature of 380 °C. Experiments of the RLSC with and without wave shaper against steel plates are carried out at standoffs of 0.5, 1.0, and 1.5 CD (charge diameter), respectively. The experimental results show that the penetration depths and structural damage effects of steel plates decrease with increasing the standoff, while the penetration depths and the damage effects of RLSC without wave shaper are much greater than that with wave shaper at the same standoff. To understand the unusual experimental results, numerical simulations based on AUTODYN-2D code are conducted to discuss the wave shaper effect, including the propagation behavior of detonation wave, the velocity and temperature distribution of reactive jet, and penetration depth of reactive jet. The simulations indicate that, compared with RLSC without wave shaper, there is a higher temperature produced inside reactive jet with wave shaper. This unusual temperature rise effects are likely to be an important mechanism to cause the initiation delay time of reactive jet to decline, which results in significantly decreasing its penetration performance.

Dynamic and stability analysis of functionally graded material sandwich plates in hygro-thermal environment using a simple higher shear deformation theory

A new simple “four-variable shear deformation” plate model is proposed in this work to demonstrate the hygro-thermal environment effects on dynamic and buckling of functionally graded material “sandwich plates” supported by “Winkler–Pasternak” elastic foundations. Equations of motion are obtained from Hamilton’s principle containing the hygro-thermal influences. This model uses only “four variables” and considers trigonometric variation of “transverse shear stress.” In addition, these stresses become zero at the upper and lower surfaces of the “sandwich plate.” The novelty of this formulation is the addition of the integral term in the field of displacement, which leads to a reduction of the number of unknowns and basic equations. Various kinds of functionally graded material “sandwich plates” are examined in this study. To verify the validity of the model, the calculated results are compared with the existing results. Comparison investigations reveal that the computed results of the proposed formulation are in excellent agreement with those of other “higher shear deformation theories.” Parametric investigation is established to demonstrate the effects of temperature rise, moisture condition, elastic foundation coefficients, and power law index on the vibration and buckling of functionally graded material “sandwich plates.”

Isogeometric analysis for size-dependent nonlinear thermal stability of porous FG microplates

In this article, we present for the first time a research analysis for the size-dependent effects on thermal buckling and post-buckling behaviors of functionally graded material micro-plates with porosities (imperfect FGM) using isogeometric analysis. A seventh-order shear deformation plate theory associated with the modified couple stress theory (MCST) is particularly imposed to capture the size-dependent phenomenon within imperfect FGM micro-plates. The material properties of imperfect FGM micro-plates with three different distributions of porosities including even, uneven and logarithmic-uneven varying across the plate thickness are derived from the modified rule-of-mixture assumption. The nonlinear governing equation for size-dependent imperfect FGM micro-plate under uniform, linear and nonlinear temperature rise is derived using the Von-Kármán assumption and Hamilton’s principle. Through numerical example, the effect of temperature rise, boundary conditions, power index, porosity volume fraction, porosity distribution pattern and material length scale parameter on thermal buckling and post-buckling behaviors of FGP micro-plates are investigated.

Outdoor Testing of a Zig-Zag Solar Air heater with and without Artificial Roughness on Absorber Plate

In this paper, thermal performance of a zig-zig solar air heater (ZZSAH) with and without using steel wire mesh on the absorber plate of the collector is experimentally investigated. The experimental work includes four inclination angles of the collector 20o, 30o, 45o, and 60o and four air mass flow rates of 0.03, 0.04, 0.06, and 0.08 kg/s under varieties of operating conditions of a geographic location of Baghdad. New correlation equations of Nusselt number are obtained from experimental results for both types of collectors where the effect of varying of the inclination angle of collector taken into consideration in the experiment. The correlations show good agreement with the present experimental data. In addition, the effects of mass flow rate and temperature rise across the efficiency of collector air heater are investigated. The results reveal that the efficiency of (ZZSAH) at 45o inclination angle reaches the highest values among other degrees of inclination angles for both types of collectors under study. The results also show that the addition of wire mesh magnifies the effect of inclination angle.

Testing of Several Paper Types as Insulators for Electric Power Systems

Abstract— This research was based on high voltage equipment failure due to an increase in temperature and humidity on insulating materials. This can cause the power system reliability to decrease. On the other hand, paper is frequently found and used in everyday life. Paper can be categorized as a solid insulator even tough its use in the electric power system can be considered as minimum. This paper aimed to determine electrical insulation characteristics of three types of paper on market and to determine the amount of failed voltage and leakage current of test materials included with other factors such as temperature rise effect as well as humidity conditions in sample testing. The employed test samples were photo paper, duplex paper, and samson craft paper with a length of 7 cm and width of 7 cm with different thickness for each paper type. Tests were carried out with two paper conditions, i.e. paper was soaked in Shell Diala B oil and was not soaked in Shell Diala B oil, so that the significance of the oil on the paper used as an ingredient in testing could be known. The test results showed that temperature and humidity affected dielectric strength magnitude and test sample leakage current value. In addition, it was also found that test sample result impregnated with Shell Diala B had a higher dielectric magnitude compared to the unimpregnated test sample. Test samples impregnated with Shell Diala B oil had a leakage current value which tended to be smaller than the unimpregnated test sample.

Effect of temperature rise on characteristics of a standing wave ultrasonic motor

Heat loss occurs in the process of energy conversion, which causes the temperature rise and performance degradation of ultrasonic motor. In this article, a novel theoretical model is developed to investigate the temperature field and output characteristics of a standing wave ultrasonic motor. The roughness of contact surface and the interaction between temperature rise and material parameters of stator are taken into account in the proposed model. The frequency–temperature characteristics of stator are studied, and the changes in the dielectric coefficients of piezoelectric materials with respect to the temperature are determined by experimental data. The accuracy and effectiveness of the developed model are validated by correlative experiment. The results show that the developed model can not only predict the temperature variation of motor in continuous operation but also evaluate the influence of surface roughness and various input parameters on output characteristics of motor. These researches will give useful guidelines for optimizing heat source and enhancing reliability of motor.

Strain-Rate-Dependent Tensile Response of Ti⁻5Al⁻2.5Sn Alloy.

This study is an experimental investigation on the tensile responses of Ti–5Al–2.5Sn alloy over a wide range of strain rates. Uniaxial tension tests within the rate range of 10−3–101 s−1 are performed using a hydraulic driven MTS810 machine and a moderate strain-rate testing system. The high-rate uniaxial tension and tension recovery tests are conducted using a split-Hopkinson tension bar to obtain the adiabatic and isothermal stress–strain responses of the alloy under dynamic loading conditions. The experimental results show that the value of the initial yield stress increases with the increasing strain rate, while the strain rate sensitivity is greater at high strain rates. The isothermal strain-hardening behavior changes little with the strain rate, and the adiabatic temperature rise is the main reason for the reduction of the strain-hardening rate during high strain-rate tension. The electron backscatter diffraction (EBSD) analysis of the post-deformed samples indicates that there are deformation twins under quasi-static and high-rate tensile loadings. Scanning electron microscope (SEM) micrographs of the fracture surfaces of the post-deformed samples show dimple-like features. The Zerilli–Armstrong model is modified to incorporate the thermal-softening effect of the adiabatic temperature rise at high strain rates and describe the tension responses of Ti–5Al–2.5Sn alloy over strain rates from quasi-static to 1050 s−1.

Antagonistic effects of multiple stressors on macroinvertebrate biomass from a temperate estuary (Minho estuary, NW Iberian Peninsula)

An ecosystem model of the Minho estuary (NW coast of Iberian Peninsula) was implemented in AQUATOX 3.1 (US-EPA) to check whether the effects of temperature rise, dry years, rainy years and river flow decrease acting isolated (single stressor) or combined (multiple stressor) would induce the same type of response on macroinvertebrate biomass variation and to identify the type of stressor interactions. The model was parameterised with site-specific and species-specific data and accounts for a food web with primary producers, benthic invertebrates, fish and detritus, with 12 biotic groups, 4 groups of detritus and 12 forcing functions.Results showed that macroinvertebrate biomass responded differently to single stressor and multiple stressor scenarios and interactions among the tested stressors were antagonistic. During medium term simulations (∼6 years), the biomass of macroinvertebrate communities from the Minho estuary was maintained or slightly increased in single scenarios of temperature rise but the occurrence of antagonistic interactions between temperature rise, river flow decrease, dry years and rainy years counteracted the increasing tendency in multiple stressor scenarios.Overall, the present results highlight the strong dependence of the system’s biomass and production on hydrodynamics and contribute to increase knowledge on the mechanistic processes behind this. Thus, we recommend an ecosystem-based management of the Minho River basin supported by models such as the present one.

Direct ethanol production from cellulose by consortium of Trichoderma reesei and Candida molischiana

Abstract Industrial cellulosic ethanol production is a challenge due to the high cost of cellulases for hydrolysis when lignocellulosic materials are used as feedstock. In this study, direct ethanol production from cellulose was performed by consortium of Trichoderma reesei and Candida molischiana. Cellulose was hydrolyzed by a fully enzymatic saccharification process using Trichoderma reesei cellulases. The produced reducing sugar was further utilized by Candida molischiana for ethanol production. Because the optimal temperature for the cellulase system is approximately 50°C, the effect of temperature rise from 30°C to 50°C on cellulose hydrolysis was investigated. The results showed that the temperature rise from 30°C to 50°C after 36 h of cultivation was the best for reducing sugar and glucose production. Under these conditions, the maximum concentrations of reducing sugar and glucose produced by T. reesei were 8.0 g/L and 4.6 g/L at 60 h, respectively. The maximum production of ethanol by C. molischiana was 3.0 g/L after 120 h.

Seismic Performance Assessment of Quintuple Friction Pendulum Isolator with a Focus on Frictional Behavior Impressionability from Velocity and Temperature

ABSTRACT This paper describes the development of a numerical model using finite element modeling (FEM) with the ability to simulate and analyze the thermal–mechanical behavior of a new generation of curved surface sliders called as Quintuple Friction Pendulum Isolators (QFPIs). The QFPI is a spherical sliding isolator with six sliding surfaces, five effective pendula, and nine stages of operation which allow for a multistage adaptive behavior depending on the amplitude of displacement. The focus of this study is on the effect of velocity, heat generation, and temperature rise, which occurs at the sliding surfaces under large friction forces and high velocities, on the frictional behavior of this new type of isolators. Heat generation is simulated through a heat source located on the sliding surfaces, with surface heat flux intensity dependent on the coefficient of friction, the contact pressure, and the velocity. At the same time of the mechanical analysis, the thermal calculation was also done and the coefficient of friction is adjusted step by step on the current temperature and velocity at the sliding surfaces. To validate the numerical approach, the hysteretic force–displacement behavior of isolator is compared by that of the experimental test result. Moreover, seismic performance of this type of new sliding isolators was analyzed and evaluated in terms of the effective stiffness, K eff, and the energy dissipated per cycle, EDC or E loop, based on EN 15129, ASCE 7-10, ASCE 7-16, and AASHTO 2014 codes. The assessment results show that the codes requirements on the maximum allowable variation in K eff and EDC are fulfilled. The numerical process can help in early studies to select the isolator materials accounting for their thermal consistency and evaluating the design properties variation of sliding isolation due to frictional heating.

Experimental Study on Compatibility of Eco-Friendly Insulating Medium C5F10O/CO2 Gas Mixture With Copper and Aluminum

The C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sub> F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">10</sub> O gas mixture has great application prospects as a potential SF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> substitute gas. It is necessary to study the compatibility of the C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sub> F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">10</sub> O gas mixture with copper and aluminum used in the electrical insulation equipment before the engineering application. In this paper, we studied the interaction of C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sub> F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">10</sub> O/CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> with copper and aluminum at various temperatures experimentally. The results show that the compatibility of copper with the C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sub> F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">10</sub> O/CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> gas mixture is obviously inferior to that of aluminum. Considering the temperature rise effect during normal operation of the equipment, it is found that the interaction between C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sub> F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">10</sub> O/CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> gas mixture and copper at 80 °C will lead to slight corrosion on the copper surface. The corrosion degree increased at the higher temperature. SEM shows that massive cubic grains will be formed on the copper surface at 150 °C–250 °C. No corrosion was observed on the aluminum surface at 150 °C ~ 250 °C, which is related to the protective effect of the oxide layer Al <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> on the aluminum. The relevant results reveal the compatibility of the C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sub> F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">10</sub> O/CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> gas mixture with metal materials and provide an important reference for the engineering application of the C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sub> F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">10</sub> O gas mixture.

Adaptation Features of Diapause Duration of the Gypsy Moth Lymantria dispar (L.) from Populations of Different Latitudinal Origination

An analysis of the influence of the sum of effective temperatures (SET) that embryos of gypsy moth (Lymantria dispar (L.)) from populations of different latitude origins receive in the midsummer—autumn period until overwintering on the diapause duration and the SET of eclosion, as well as an assessment of the effect of short-term temperature rise during the dormancy period on the eclosion duration and diapause strength, were performed. The effect of the midsummer—autumn SET on the diapause duration and on the SET of spring eclosion subject to conditions of diapause and subsequent quiescence is found. We show that a short-term rise in temperature over the embryo development threshold leads to a proportional decrease in the eclosion duration when the SET of eclosion was lower than 200 degree days. If the SET of eclosion is higher than 200 degree days, the effect of this exposure either has no effect on the eclosion duration or led to stronger dormancy. A short-term temperature rise leads to an increased mortality of embryos that receive a low midsummer—autumn SET (approximately 400–450 degree days with a threshold of approximately 7°C). Embryos that receive a high midsummer—autumn SET (approximately 1300–1500 degree days with a threshold of approximately 7°C) show no increased mortality. On the basis of these results, we assume that the populations of southern origination have a stronger diapause due to the adaptation to the short-term casual temperature rise above the embryo development threshold in the winter—spring period, which may lead to the premature eclosion of gypsy moth larvae.

Size dependent thermo-electro-mechanical nonlinear bending analysis of flexoelectric nano-plate in the presence of magnetic field

The present paper studies the thermo-electro-magnetic mechanical behavior of a flexoelectric nano-plate using a modified flexoelectric theory and application of classical Kirchhoff plate theory. Size and flexoelectric effects are considered. Using the variation method and the principle of minimum potential energy in the coupling form, for the first time, the nonlinear governing differential equations of the nano-plate and the relevant boundary conditions are obtained. The nano-plate is subjected to mechanical, electrical, magnetic and thermal loadings and is simply supported on all edges. Moreover, in the present study, analytical solutions are presented to investigate the effects of length scale parameters, geometric parameters, mechanical loading, and temperature rise of the nano-plate lower surface, the external electric potential, and the external static magnetic flux density on the magneto-thermo-electro-elastic behavior of the nano-plate. In order to verify the presented formulations, the results are compared to analytical results found in the literature. Due to high stain gradients in nano-scales, the results indicate that the flexoelectricity has a larger influence in plates with smaller thicknesses. The results also show that, in the presence of flexoelectricity and static magnetic field, the rigidity of the nano-plate increases. Also, the deflection and the generated electric potential along nano-plate thickness decrease.

Noninvasive Kalman Filter Based Permanent Magnet Temperature Estimation for Permanent Magnet Synchronous Machines

Permanent magnet temperature (PMT) is crucial to high-performance control and condition monitoring of permanent magnet synchronous machines (PMSMs). This paper proposes a noninvasive PMT estimation approach based on the PMSM steady-state equation. First, a linear temperature model, dependent solely on the PMT, is derived from the steady-state equation and the PM thermal model. Thus, the PMT can be directly estimated from the measurements using the derived linear model. In order to improve the estimation performance, a linear state-space model is developed based on the derived model, and the Kalman filter is employed for PMT estimation. The inverter nonlinearity is considered and compensated in the proposed model to improve the estimation performance. Compared with the existing methods, the proposed approach is noninvasive and computationally efficient. More importantly, the derived model does not involve machine parameters such as winding resistance and self and mutual inductances, and thus, the proposed approach is independent of winding temperature rise, magnetic saturation, and cross-coupling effect. The proposed approach is evaluated with extensive experiments under various speed and load conditions.

On the dynamic behavior and relationship to mechanical properties of cold-rolled Fe-0.2C-15Mn-3Al steel at intermediate strain rate

The dynamic tensile behavior of Fe-15Mn-3Al-0.23C TRIP/TWIP steel was studied at intermediate strain rates in the range of 7–700 s−1. The results showed that transformation induced plasticity (TRIP) effect, twinning induced plasticity (TWIP) effect, dislocation glide and adiabatic temperature rise effect coexisted during dynamic deformation. With the increase of strain rate from 7 to 70 s−1, the number of deformation twins increased and some intersecting twins appeared. However, when the strain rate approached 700 s−1, the amount of deformation twins were decreased and intersecting twins disappeared. During deformation at strain rates from 7 to 700 s−1, the strain rate had no significant effect on TRIP effect, and deformation twinning was the main deformation mechanism. The ultimate tensile strength (UTS) showed a positive strain rate sensitivity with increased strain rate, and the experimental steel exhibited remarkable mechanical properties with the product of ultimate tensile strength and total elongation (PSE) of 61.5 GPa% at the strain rate of 70 s−1.