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Migration of colloidal particles induced by temperature gradients is commonly referred to as thermodiffusion, thermal diffusion, or the (Ludwig-)Soret effect. The thermophoretic force experienced by a colloidal particle that drives thermodiffusion consists of two distinct contributions: a contribution resulting from internal degrees of freedom of single colloidal particles, and a contribution due to the interactions between the colloids. We present an irreversible thermodynamics based theory for the latter collective contribution to the thermophoretic force. The present theory leads to a novel "thermophoretic interaction force" (for uncharged colloids), which has not been identified in earlier approaches. In addition, an N -particle Smoluchowski equation including temperature gradients is proposed, which complies with the irreversible thermodynamics approach. A comparison with experiments on colloids with a temperature dependent attractive interaction potential over a large concentration and temperature range is presented. The comparison shows that the novel thermophoretic interaction force is essential to describe data on the Soret coefficient and the thermodiffusion coefficient. • An irreversible thermodynamics based theory is presented leading to a novel "thermophoretic interaction force" on colloidal particles that originates from their mutual interactions. • Explicit microscopic expressions are found for the Soret coefficient and the thermodiffusion coefficient in terms of the (equilibrium) pair-correlation function. • The novel thermophoretic interaction force is essential to be able to describe the experimental data. [ABSTRACT FROM AUTHOR]

Exchanges and interactions between water masses are typically concentrated across ocean fronts, requiring targeted sampling. As fronts are dynamic in their spatiotemporal extent, they can be hard to map with limited sampling resources. In this paper, we use horizontal temperature gradient as the defining feature of a front to adapt the path of an autonomous underwater vehicle to follow these regions of scientific interest. We present results from simulations and successful field operations in the Barents Sea, where the vehicle equipped with a microstructure sensor crossed the polar front while adapting its trajectory to the front position. Using in situ measurements, we estimate the temperature gradient across the polar front and cross it at different depths. We show that the vehicle is able to estimate and detect the temperature gradient maximum and to adjust its path to provide measurements of temperature, salinity and microstructure along its path, on both sides of the front. This is a step toward the integration of turbulence measurements on autonomous underwater vehicles, showing promise of more targeted sampling of turbulence in regions of large spatial gradients and interactions between water masses, such as fronts. The horizontal vehicle path complements the more traditional vertical profile measurements, providing a finer horizontal spatial resolution. The adaptive behavior of autonomous agents contributes to increased accuracy in targeted measurements as well as expanded resource utilization. [ABSTRACT FROM AUTHOR]

Soil microbes are essential for regulating carbon stocks under climate change. However, the uncertainty surrounding how microbial temperature responses control carbon losses under warming conditions highlights a significant gap in our climate change models. To address this issue, we conducted a fine‐scale analysis of soil organic carbon composition under different temperature gradients and characterized the corresponding microbial growth and physiology across various paddy soils spanning 4000 km in China. Our results showed that warming altered the composition of organic matter, resulting in a reduction in carbohydrates of approximately 0.026% to 0.030% from humid subtropical regions to humid continental regions. These changes were attributed to a decrease in the proportion of cold‐preferring bacteria, leading to significant soil carbon losses. Our findings suggest that intrinsic microbial temperature sensitivity plays a crucial role in determining the rate of soil organic carbon decomposition, providing insights into the temperature limitations faced by microbial activities and their impact on soil carbon‐climate feedback. [ABSTRACT FROM AUTHOR]

With the increasing demands for groundwater management in industrial and environmental engineering, the research and application of air sparging remediation technology have become crucial for enhancing multiphase flow control. Particularly under complex geological conditions with temperature gradients, understanding and predicting the behavior of multiphase flows are essential for improving the efficiency and safety of remediation technology. Currently, most studies focus on the analysis of multiphase flows under static conditions, with fewer assessments on the impact of dynamically changing temperatures and pressures, thus limiting the accuracy and reliability of models in practical applications. Addressing this research gap, this study proposes a fully transient temperature-pressure field coupled model, along with a corresponding iterative solution algorithm, to accurately simulate the dynamic characteristics of underground multiphase flows under varying temperature gradients. The progress of this research extends our understanding of the mechanisms of multiphase flow in air sparging, supporting technological innovation and environmental protection efforts in related fields. It also offers new solutions for resource development and pollutant management under complex geological conditions. [ABSTRACT FROM AUTHOR]

To reduce room heating energy consumption and improve energy utilization efficiency, this paper proposed a method for evaluating the energy efficiency of office heating based on 'ineffective heat supply' and 'ineffective heat supply ratio' and established an energy consumption analysis model. Using the office in hot summer and cold winter areas as an example, the heating energy consumption and energy utilization efficiency were simulated. The results indicate that better thermal comfort is achieved in the working area of Air Conditioning Lower Installation (ACLI) compared to Air Conditioning Upper Installation (ACUI). The ineffective heat supply ratio of the room increases with the rise of air supply temperature and decreases with the increase of air supply speed. As the supply air temperature increases from 25°C to 50°C, the ineffective heat supply ratios for ACUI and ACLI increase by 35.9% and 14.9%, respectively. The use of low-temperature heat medium is more energy-efficient than high-temperature heat medium. When the air supply speed increases from 0.8 to 3.2 m/s, its ineffective heat supply ratio decreases by 44.6% and 7.8%, respectively. Air speed change significantly impacts ACUI's ineffective heat supply ratio, with ACLI more energy efficient at lower speeds. [ABSTRACT FROM AUTHOR]

This paper presents the results of the calculation of black ice thickness, as well as conductive heat fluxes inside the ice and at the water–ice boundary during the winter in the shallow boreal Lake Vendyurskoe (Russia). The calculation was carried out on the basis of experimental data obtained from a thermistor chain with nine sensors, five of which were successively frozen into the black ice during the winter of 1995–1996. Data processing was carried out by two methods, whose novelty lay in the simultaneous use of the temperature series of two sensors frozen into the ice and those that were in the water column directly under the lower ice boundary. The resulting estimates of black ice growth rates varied widely: maximum values (up to 8.5 mm/day) were observed in December during first month of ice period, with an average growth rate of 3.4 mm/day from December to the end of February. The heat flux in the black ice sheet varied significantly over synoptic time intervals; the highest values (up to 40 W/m2) were observed during the first two weeks of measurements, then a downward trend was noted, to values of ~10 W/m2. Black ice was isothermal from the end of February to the end of April due to the release of water on the ice surface after heavy snowfall. During this period the heat flux inside the black ice was zero, and there was no increase in black ice thickness. The calculation of the water–ice heat flux gives results that are very sensitive to both measurement limitations and the variability of external parameters. However, the estimates of this flux for moments in time when the sensors were frozen in the ice are values 1–2 W/m2, which are quite close to the previous estimates for Lake Vendyurskoe. The limitations of the presented method are related to the thermal inertia of black ice and make it possible to calculate of ice thickness with a time delay of several days. To quantify the effects of thermal inertia of ice, a model problem of heat propagation in the ice sheet is considered for the case of periodic temperature changes at its upper boundary. The attenuation of the amplitude and the delay of a heat wave during its propagation in the ice are estimated, and accordingly, the conditions, under which the temperature profile in the ice sheet is close to linear, are analyzed. [ABSTRACT FROM AUTHOR]

This paper presents the results of the calculation of black ice thickness, as well as conductive heat fluxes inside the ice and at the water–ice boundary during the winter in the shallow boreal Lake Vendyurskoe (Russia). The calculation was carried out on the basis of experimental data obtained from a thermistor chain with nine sensors, five of which were successively frozen into the black ice during the winter of 1995–1996. Data processing was carried out by two methods, whose novelty lay in the simultaneous use of the temperature series of two sensors frozen into the ice and those that were in the water column directly under the lower ice boundary. The resulting estimates of black ice growth rates varied widely: maximum values (up to 8.5 mm/day) were observed in December during first month of ice period, with an average growth rate of 3.4 mm/day from December to the end of February. The heat flux in the black ice sheet varied significantly over synoptic time intervals; the highest values (up to 40 W/m2) were observed during the first two weeks of measurements, then a downward trend was noted, to values of ~10 W/m2. Black ice was isothermal from the end of February to the end of April due to the release of water on the ice surface after heavy snowfall. During this period the heat flux inside the black ice was zero, and there was no increase in black ice thickness. The calculation of the water–ice heat flux gives results that are very sensitive to both measurement limitations and the variability of external parameters. However, the estimates of this flux for moments in time when the sensors were frozen in the ice are values 1–2 W/m2, which are quite close to the previous estimates for Lake Vendyurskoe. The limitations of the presented method are related to the thermal inertia of black ice and make it possible to calculate of ice thickness with a time delay of several days. To quantify the effects of thermal inertia of ice, a model problem of heat propagation in the ice sheet is considered for the case of periodic temperature changes at its upper boundary. The attenuation of the amplitude and the delay of a heat wave during its propagation in the ice are estimated, and accordingly, the conditions, under which the temperature profile in the ice sheet is close to linear, are analyzed.

Reverse electrodialysis in nanochannels has become an innovative method to obtain clean energy. To enhance the power generation efficacy of the nanochannel, the finite element method was employed to model the impact of the temperature gradient on the power generation efficiency of the conical channel. The investigation primarily focused on the nanochannel structure, as well as the direction and magnitude of the solution temperature gradient. The results show that the overall power generation performance is superior for ions diffusing from the large pore end to the small pore end in the presence of a negatively charged wall surface. The nanochannel system with a negative temperature gradient shows better power generation performance than that with a positive temperature gradient under the same nanochannel parameters and solution conditions. [ABSTRACT FROM AUTHOR]

Quasi-collinear geometry is a special configuration of acousto-optic (AO) diffraction that provides an extremely large AO interaction length for achieving extremely high spectral resolution of AO tunable filters (AOTFs). Large AO interaction length also makes it possible to implement multifrequency diffraction in quasi-collinear AOTFs, which has found multiple applications in modern optoelectronics. The most widespread of them being ultrashort laser pulse shaping when the pulse shape and spectral composition is controlled by the spectral composition of the ultrasound pulse aroused in the AO crystal. The operation of quasi-collinear AOTFs is accompanied by the appearance of the temperature gradients in the AO device mainly due to the acoustic power absorption by the material. We experimentally assessed the influence of these gradients on the AOTF spectral characteristics. A theoretical model based on the Raman–Nath equations was proposed, which allows to consider the influence of ultrasound attenuation and temperature gradients on the AOTF transmission. This model is valid for transmission simulations both in single- and modulated-frequency AOTF operation modes. The study includes the effects of acoustic wave attenuation and AO phase matching shift caused by inhomogeneous crystal temperature along the optical beam path. The compensation strategy based on ultrasound frequency and magnitude adjustment is proposed for minimizing the effect of temperature gradients and acoustic field attenuation on AOTF spectral transmission for broadband operation in ultrashort laser pulse shaping. [ABSTRACT FROM AUTHOR]

In this work, we simulated the heat transfer in a two-vessel (1-m3, length-to-diameter ratio of 4) industrial plant to assess the effect of the temperature gradients formed during the reconditioning stage on the extraction curves. We simulated the extraction of 1-mm particles using 5 mm/s of CO 2 at 48 MPa and 40 °C (case with an imposed temperature gradient) or 60 °C (case with temperature gradients from the reconditioning stage), with the service fluid at 60 °C. The results of these non-isothermal extractions were compared with those obtained in representative isothermal cases. The temperature gradients slightly affected the cumulative extraction curves in non-isothermal cases. We considered the presence of a basket containing the solid substrate. We also changed the superficial CO 2 velocity to 3 or 10 mm/s and the particle size to 0.50 or 1.25 mm to compare the extraction curves. The effects of the basket and the changes in superficial CO 2 velocity and particle size were minor. We simulated a limit case with higher temperature and pressure (80 °C and 70 MPa), where the extraction time was extremely short (10 min) and more significant temperature gradients were formed during the reconditioning stage. We observed more significant differences at this extreme extraction condition than when using an isothermal process at the required extraction temperature. [Display omitted] • Faster depressurizations and pressurizations caused larger temperature gradients. • Temperature gradients affected extraction curves slightly at the selected reference condition. • Changes in CO 2 velocity and particle size slightly affected the extraction curve. • Very high temperature and pressure increased differences with an isothermal case. • Neglecting radial variations in temperature worsened extraction predictions. [ABSTRACT FROM AUTHOR]

Simulating quantitatively far-from-equilibrium conditions, which is relevant to a host of rapid solidification processes, has remained a major challenge where theoretical models and physical mechanisms for far-from-equilibrium solid–liquid (SL) interface are essential. Herein, we investigate the effects of far-from-equilibrium state and external strain on SL interfacial properties by using capillary fluctuation method and models based on transition rate theory. Under an extreme temperature gradient (TG), both SL interfacial stiffness (S) and SL interface velocity (v) are found to increase with TG. The nonlinear relationship between v and temperature is revealed over a large undercooling range (640 K). It is found that an external strain (ϵ) of 1%–3% could decrease S by 10%–30%. v is found to increase with external strains at large undercooling. Tensile strains decrease the activation energy (Q) and viscosity, thus facilitating SL interface movement. A strain-dependent Gibbs–Thomson condition is proposed by incorporating linear S - ϵ and Q - ϵ relations. Our systematically theoretical discussion on the far-from-equilibrium SL interfacial properties could provide a predictive guideline on SL interface behavior in the additive or extreme manufacturing. [Display omitted] [ABSTRACT FROM AUTHOR]

Summary: Underwater wireless optical communication (UWOC) turns out to be a primary sought alternative to wireless technology, which can provide high data rate, enormous bandwidth, and low deployment cost and resolve the crowded radio frequency band issues. The performance of the UWOC link is significantly affected by the turbulent ocean environment. In this paper, the different turbulence scenarios such as salinity gradients, temperature gradients, and air bubbles are considered to model the turbulent nature of the ocean environment experimentally. These turbulent conditions induce severe intensity fluctuations in the received optical signal. These intensity fluctuations are modeled stochastically, and a novel turbulence channel model is proposed, which excellently fitted with the experimental data. The conformity of the proposed model is validated by performing a goodness of fit test in terms of R2 and root mean square error (RMSE) coefficients. The results show that for all the considered turbulent scenarios, the Gaussian mixture model better approximates the experimental observations than the Weibull distribution. As the strength of the turbulence increases, the chances of link outage and the probability of bit errors increase. At a flow rate of 4 L/min, the bit error rate (BER) of 10−20, 10−14, and 10−10 is recorded under clear water, salinity, and temperature gradient channel conditions, respectively. It is observed that the air bubbles have a significant impact on the propagating optical beam in comparison to temperature and salinity‐induced turbulence. Moreover, a close agreement between the proposed model and the experimental data is also observed, which makes the proposed model more appropriate to describe the turbulent ocean environment. [ABSTRACT FROM AUTHOR]

The solar flux distribution on the Parabolic Trough Collector (PTC) absorber tube is extremely non-uniform, which causes non-uniform temperature distribution outside the absorber tube. Therefore, it generates high thermal stress which causes creep and fatigue damage. This presents a challenge to the efficiency and reliability of parabolic trough receivers. To override this problem, we have to homogenize the heat flux distribution and enhance the heat transfer in the receiver's absorber tube to improve the performance of the PTC. In this work, 3D thermal and thermal stress analyses of PTC receiver performance were investigated with a combination of Monte Carlo Ray-Trace (MCRT), Computational Fluid Dynamics (CFD) analysis, and thermal stress analysis using the static structural module of ANSYS. At first, we studied the effect of the receiver tube material (aluminium, copper, and stainless steel) on heat transfer. The temperature gradients and the thermal stresses were compared. Second, we studied the effect of the addition of nanoparticles on the working Heat Transfer Fluid (HTF), employing an Al2O3-H2O based nanofluid at various volume concentrations. To improve the thermal performance of the PTC, a nanoparticle volume concentration ratio of 1%-6% is required. The results show that the temperature gradients and thermal stresses of stainless steel are significantly higher than those of aluminium and copper. From the standpoint of thermal stress, copper is recommended as the tube receiver material. Using Al2O3 in water as an HTF increases the average output temperature by 2%, 6%, and 10% under volume concentrations of 0%, 2%, and 6% respectively. The study concluded that the thermal efficiency increases from 3% to 14% for nanoparticle volume fractions ranging from 2% to 6%. [ABSTRACT FROM AUTHOR]

Temperature gradients are significant in the fatigue life assessment. Thermal loading conditions were suspected to affect temperature gradients and thermal stresses in structures. In the present work, thin-walled plates and tubes were experimentally investigated to quantify the effects of thermal loads on the through-thickness temperature gradients, and finite element models were developed based on the experiments and used to generate more general correlations. It is confirmed that both transient peak temperature gradient and steady-state values are linear to heating power and cooling conditions, and are insensitive to plate thicknesses. By introducing the nondimensional temperature gradient, the temperature distribution in thin-walled structures can be estimated with reasonable accuracy. [ABSTRACT FROM AUTHOR]

In a composite layer that comprises of a porous layer which is sparsely packed and saturated with two component incompressible fluid and above this porous layer lays a layer of the same fluid, with variable heat sources or sinks in both the layers double diffusive non-Darcian Benard Marangoni (DDNBM) convection is investigated. The upper surface of the composite layer has Marangoni effects which depend on temperature and concentration, whereas the lower surface is rigid. The inverted parabolic, parabolic and linear temperature profile is applied to this composite layer, which is surrounded by adiabatic boundaries. The appropriate thermal Marangoni numbers (TMANs) which are the eigen values (EVs) are calculated for all the three temperature gradients. The impact of different parameters on the EVs with respect to depth ratio is examined, thoroughly. The parameters that effect DDNBM convection are found. [ABSTRACT FROM AUTHOR]

The problem of B`enard-Magneto-Marangoni convection in a composite layer which is infinite along x and y directions is considered for the Darcian case in the presence of constant heat source/sink in both the layers. This composite layer is subjected to uniform and nonuniform temperature gradients. The eigenvalue, thermal Marangoni number is obtained in closed form with the lower surface rigid and upper surface free with surface tension effects for the velocity and isothermal temperature boundary combinations. The influence of porous parameter, magnetic field and nonuniform temperature gradients on the Eigen value problem are discussed. It is experiential that the effect of heat source/sink in the fluid layer is dominant on the eigenvalue over the same in the porous layer. The important parameters like Chandrasekhar number, modified internal Rayleigh number and thermal ratio which control B`enard-Magneto-Marangoni convection are discussed in detail. [ABSTRACT FROM AUTHOR]

Temperature-gradient-mechanical fatigue (TGMF) is a significant concern in internal cooling turbine blades. In the present study, the through-thickness temperature gradient was determined by the inverse heat conduction method and investigated in TGMF. Using the continuum damage mechanics, the environmental impact was identified as the primary contributor to the in-phase TGMF damage. A damage accumulation model encompassing fatigue, creep and environmental impact was established and provided satisfactory accuracy in TGMF life assessments. The main conclusion is that temperature gradients do not change the fracture mode but significantly increase stress levels by at least 20%, accelerating oxidation damage and resulting in a TGMF life ca. 10 times shorter than that of TMF. • Identified effects of temperature gradients to thermomechanical fatigue lives. • Quantified thermomechanical fatigue damage processes by continuum damage concept. • Generated damage evolution models for isothermal fatigue, TMF and TGMF fatigue. [ABSTRACT FROM AUTHOR]

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Modeling the realistic burning behavior of condensed-phase fuels has remained out of reach, in part because of an inability to resolve the complex interactions occurring at the interface between gas-phase flames and condensed-phase fuels. The current research provides a technique to explore the dynamic relationship between a combustible condensed fuel surface and gas-phase flames in laminar boundary layers. Experiments have previously been conducted in both forced and free convective environments over both solid and liquid fuels. A unique methodology, based on the Reynolds Analogy, was used to estimate local mass burning rates and flame heat fluxes for these laminar boundary layer diffusion flames utilizing local temperature gradients at the fuel surface. Local mass burning rates and convective and radiative heat feedback from the flames were measured in both the pyrolysis and plume regions by using temperature gradients mapped near the wall by a two-axis traverse system. These experiments are time-consuming and can be challenging to design as the condensed fuel surface burns steadily for only a limited period of time following ignition. The temperature profiles near the fuel surface need to be mapped during steady burning of a condensed fuel surface at a very high spatial resolution in order to capture reasonable estimates of local temperature gradients. Careful corrections for radiative heat losses from the thermocouples are also essential for accurate measurements. For these reasons, the whole experimental setup needs to be automated with a computer-controlled traverse mechanism, eliminating most errors due to positioning of a micro-thermocouple. An outline of steps to reproducibly capture near-wall temperature gradients and use them to assess local burning rates and heat fluxes is provided.

The geographical position of the Arctic front and two branches of the Polar front over Europe was determined during the period 1995--2015 using calculated grid fields of the thermal frontal parameter in the troposphere layer of 850--700 hPa. It was revealed that the geographical position of climatological fronts changed both in the cold and warm periods of the year in comparison with climate data. The most recent standard reference period of 1961--1990 recommended by WMO (WMO, 2017) was used for comparison. It is shown that in January there was a shift of the northern and southern branches of the Polar front to the north compared to the reference climate period, and in July the convergence of both branches of the Polar front in the middle latitudes was observed. The Arctic front was characterized by a northern location compared to the climate in both January and July. It is revealed that the main areas of frontogenesis in the cold period of the year were the sea surface, namely, the southern regions of the Norwegian Sea, the central part of the Baltic Sea, and the western half of the Mediterranean Sea. In the summer, more active atmospheric fronts were over the continent in the area of the mountain systems such as the south of the Scandinavian mountains, the north of the Alps and Pyrenees, the Urals, and the lower Volga region. The Arctic front intensified over the Barents and Norwegian Seas in all seasons of the year. [ABSTRACT FROM AUTHOR]

In this study, we present a zinc oxide (ZnO) thin film-based p-n type thermoelectric energy harvester that can generate thermoelectric power particularly under plane-vertical temperature gradients. The performance of the proposed p-n type thermoelectric energy harvester, consisting of both n-type Al-doped ZnO (ZnO:Al) and p-type Ag & N co-doped ZnO (ZnAgO:N) thin films, is evaluated by measuring its thermoelectric open-circuit voltage (${V}_{oc}$) and short-circuit current density (${J}_{sc}$) for the negative and positive plane-vertical temperature gradients, revealing better thermoelectric performance under larger temperature gradients. Moreover, the thermoelectric principle of the proposed p-n type thermoelectric energy harvester is investigated by comparing the thermoelectric performance of the proposed p-n type energy harvester with those of the other p-i-n type energy harvesters containing differently thick undoped ZnO (${i}$ -ZnO) inter-layers between the ZnO:Al and ZnAgO:N thin films. Besides, the thermoelectric principle is further verified employing the scenario of asymmetric temperature gradients. The thermoelectric principle of the proposed p-n type energy harvester is discussed based mostly on the fundamentals of thermoelectricity that charged carriers diffuse from hot to cold side in thermoelectric materials, suggesting that the thermoelectric power of the proposed harvester results from the diffusion of both the electrons and holes according to the plane-vertical temperature gradients. Overall, this study focuses mainly on the fabrication and characterization of the thermoelectric energy harvester that can generate thermoelectric power under the plane-vertical temperature gradients, including the experimental analysis on its thermoelectric principle. [ABSTRACT FROM AUTHOR]

The paper considers the problem associated with the creation of databases. The review of available global, traditional soil databases is given. It is noted that they are of great scientific and practical importance. The description of the developed relational database «Heat Soil Portraits» in Microsoft Access is presented, based on the positive concept of representative soil profiles. The database contains information about the structural organization and thermal properties of natural and technogenic soils in Central Siberia. To create the database, we used materials from a morphological description, photographing, and ground radiometric survey in the thermal range of soil profiles obtained by the authors during the expeditionary work. Radiometric survey of soils was carried out according to the author’s method using a portable thermal camera. The structure of the designed database, its content and attributes are developed. Currently, the database includes information on 20 soil profiles of the main soil types and technogenic surface formations that are common in Central Siberia. The procedure for replenishing the created database with new information is simple to perform. A feature of the proposed database is the presence of photographs and thermal portraits attached to the description of a particular soil profile, which display the temperature distribution and structural organization of the soil profile. For each soil profile, temperature gradients are calculated that characterize the specific thermophysical properties of organogenic and mineral horizons. The prospect of DB development is replenishment with the results of radiometric surveys carried out in different seasons of the year and in different conditions of soil formation. Thus, the materials contained in the database can be used to assess the temporal and spatial variability of soils as a result of exposure to natural and anthropogenic factors.

200 MW steam turbines of DTEK Lugansk TPP units have operated for about 305–330 thousand hours with a total number of starts from 1.438 to 1,704, as of the end of 2019. The term for extending the operation of high-temperature power equipment between scheduled preventive maintenances has expired. When extending the operation of cylinder bodies and rotors, one should also pay attention to steam distribution elements. A peculiarity of the re-extension of the operation of a 200 MW power unit is the beyond-design operating time of power equipment of more than 250 thousand hours and the operation of equipment in maneuverable modes (more than 1,700 starts from various thermal states), with covering peaks of the electrical load with the excess of the number of starts for certain types of equipment by two to three times. Such a significant number of variable operating modes negatively affects the life cycle of equipment and requires studying the influence of the main damage mechanisms on the metal of cast components. The paper presents a calculated study of the thermal and stress-strain states of high- pressure (HP) and intermediate-pressure (IP) control valves of a K-200-130 turbine. The calculations were carried out using three-dimensional geometric models, as well as taking into account real operating conditions. The geometric model of HP control-valve bodies was constructed taking into account the complex geometry during the transition from the inlet nozzles to the valve vapor volume with a subsequent narrowing of the outlet nozzle section to the control stage of the HP cylinder. Similarly, the geometric model of IP control-valve bodies was constructed taking into account the complex spatial geometry according to the drawings provided by the operating organization. A numerical study of the thermal and stress-strain states was carried out for typical operating modes, using the finite element method. Start-up modes were investigated in a non-stationary setting, while constant ones – in a stationary setting. The thermal states of HP and IP control valves were calculated for three variants of startup modes: cold-startup mode at an initial metal temperature of 100 °C, warm-startup mode at an initial metal temperature of 250 °C, and hot-startup mode at an initial metal temperature of 410 °C. The boundary conditions for thermal state calculations were determined using real and most representative startup schedules provided by the power plant. When calculating thermal states for different startup modes, the dynamics of changes in temperature gradients was taken into consideration. During the stress-strain state studies, the main zones of stress concentration in control valves of a K-200-130 steam turbine were established.

The reproductive performance of cattle can be suppressed by heat stress. Reproductive organ temperature, especially ovarian temperature, may affect follicle development and ovulation. The establishment of a technique for long-term measurement of ovarian temperature could prove useful in understanding the mechanisms underlying the temperature-dependent changes in follicular development and subsequent ovulation in cows. Here we report a novel method facilitating long-term and continuous recording of ovarian parenchymal temperature in cows. The method revealed that the ovarian temperature in the luteal phase was constantly maintained lower than the vaginal temperature, and that the diurnal temperature variation in the ovary was significantly greater than that in the vagina, suggesting that the ovaries may require a lower temperature than other organs to maintain their functions. This novel method could be used for the further understanding of ovarian functions during estrous cycles in cows.

Since hotspots and temperature gradients are reliability and performance-critical issues in processors, thermal awareness finds a vital place in the processor design cycle. Incorporating thermal awareness at the level of physical design, this work proposes a new, fast, and efficient thermal aware placement algorithm called the Thermal Aware Matrix Placement Optimizer (TAMPO) for gate arrays. The algorithm TAMPO is composed of the following components: an improved heat diffusion aware cell arrangement technique called the Initial Matrix Generator (IMaGe), a unique stochastic thermal model based on a thermally improved interpretation of the well known Matrix Synthesis Problem (MSP) and a Simulated Annealing (SA) engine for finding the global optimum solution. TAMPO targets to reduce the peak temperature while maintaining improved values of temperature gradients and the standard deviation in cell temperature with respect to the average chip temperature. This work also presents a methodology, the Co-optimized TAMPO, which extends the concept of TAMPO to simultaneously optimize the thermal attributes and the wirelength of a chip. The proposed algorithms realize a placement in matrix arrangement and upon experimentation on the ISCAS89 benchmark circuits encouraging results have been obtained.

This study examined 30-year of in situ observations (1981–2010) to determine monthly, and diurnal characteristics of near-surface temperature gradients (TG) in the Sudanese desert, both spatially and with elevation. The TG variation, along with its spatial and elevation dependence, forcing mechanisms for its variability, and its relationship with moisture and gradients of other climatic variables, were evaluated using a multi-collinearity approach and empirical analysis, respectively. A distinct annual cycle was observed in both the temperature gradient (or lapse rate) with elevation (TGE) and the temperature gradient with latitude (TGLat). The TGE is strongly negative during the warmer months (summer) and less strongly negative (or even positive) during the colder months (winter). However, for TGLat, the results are reversed. The mean TGE value steepens during the summer due to intense adiabatic cooling during the day and less inversion during the night, while this process is reversed for the observed shallower TGLat value in the same season. This result is attributed to desert characteristics at the northern lower elevations or higher latitudes, as well as the effects of the ITCZ, moisture, and cloud cover as a result of high elevations at lower latitudes in the south and southwest region. Low solar insolation, and Mediterranean cold airflow and littoral effect, combined with inversion and radiative cooling at lower elevations or northern higher latitudes, lead the TGE (TGLat) value to be shallow (steep) during the drier months. Excluding the inversion and radiative cooling at night, this effect is more pronounced in the winter. The extreme high and low values of TGE and TGLat, as well as their diurnal range, were found to strongly coincide with variations in the equatorial trough, as well as diurnal radiative energy differences and the regional synoptic phenomenon. In addition to being valuable for hydro-climatic, ecological, and agricultural modeling, this study can be replicated in other tropical desert areas around the world to gain a better understanding of desert’s climate.

In adiabatic thermal analysis, correct measurement of temperature is usually ensured by means of a calibration procedure and thermal inertia corrections. However, there is a significant gradient within system, which not only makes the obtained test results inaccurate, but also causes serious errors in subsequent kinetic calculations and thermal risk assessment. Thus, estimations of the temperature gradients, which appear into the sample, are of highest interest to choose the right operational conditions that minimize that gradient. In this work, the CFD software has been applied to study this temperature gradient issue in adiabatic system. In view of the causes of temperature gradients, the influencing factors and the resulting analysis errors are all deeply researched. In addition, three different kinds of adiabaticity control model cases have also been simulated to explore the right operational conditions that minimize gradient and provide more reliable kinetics and thermal hazard parameters (Q∞, k0, Ea, n, TD24, TCL). After a comparative study, the authors define the more reliable operational conditions, which include selecting a suitable temperature response value and the adiabatic temperature control model. Finally, the reliability of the adiabaticity control model that achieves the minimum temperature gradients and provides the most accurate calculation results was verified through the different adiabatic tests. [ABSTRACT FROM AUTHOR]

Non‐structural carbohydrate (NSC) storage may be under strong selection in woody plant species that occur across broad environmental gradients. We therefore investigated carbon (C) allocation strategies in a widespread non‐native woody plant, Tamarix. We predicted that genotypes with exposure to episodic freeze events would show elevated NSC concentrations compared to warm‐adapted genotypes with the trade‐off of reduced growth and reproduction relative to warm‐adapted populations.We established an experimental common garden using genotypes of Tamarix, sourced across a strong thermal gradient within the introduced range. We measured seasonal NSC storage in coarse roots and stems, above‐ground growth and flower production.Autumn NSC concentrations were 50% higher in genotypes from sites with episodic spring freeze events compared to genotypes from warmer sites. These cold‐adapted genotypes also had a 2.3‐fold higher starch to soluble sugar ratio than warm‐adapted genotypes. Across all genotypes and seasons, NSC storage was inversely correlated with growth and reproduction.Results suggest that Tamarix from colder locations cope with freeze events by maintaining large storage pools to support tissue regrowth, but with the trade‐off of overall reduced growth and reproduction. Our results are consistent with rapid selection in C allocation strategies in response to climate in introduced woody species. A free Plain Language Summary can be found within the Supporting Information of this article. [ABSTRACT FROM AUTHOR]

The complexity of roller quenching equipment restricts research on the heat transfer mechanism of ultrathick plates, and the cooling law requires further clarification. In this study, the distributions of temperature gradient, average cooling speed, and heat loss during quenching are analyzed using a 220 mm thick steel plate, and inverse heat conduction is used to determine the surface heat transfer conditions. An ultrathick steel plate is subjected to high‐pressure and low‐pressure water in turn for strong and lasting cooling. Due to the different flow regions on the upper and lower surfaces, the flow from the lower nozzle is slightly higher than that from the upper nozzle, thereby resulting in a good cooling symmetry between the upper and lower surfaces. The results provide an important basis for the optimization of roller quenching technology for ultrathick steel plates. [ABSTRACT FROM AUTHOR]

In the materials of this article the estimation of energy loading of metal friction elements of brakes is given and the following questions are considered: a design and work of frictional knots of brakes and their settlement schemes; internal and external parameters of metal-polymer friction pairs of tribosystems taking into account their energy load. It is established that the formation of the temperature regime of metal friction elements (rims of pulleys and drums, discs) of brake devices is significantly influenced by such factors as the ratio between their mass, heating (polished) and cooling (matte) and the rate of these processes. The quality and reliability of the created designs of friction units of brake devices depend on the processes, phenomena and effects that occur during the frictional interaction of the microprojections of their friction pairs. The contact of the microprojections is discrete in nature and is estimated by the dynamic coefficient of mutual overlap of friction pairs, and its value is up to 0.25 (for disc brake pads) and up to 0.75 (for drum and tape brake pads). According to the molecular-mechanical model of electrothermomechanical friction, the interaction of microroughnesses of the surfaces of friction bodies can be represented in the form of a narrow sliding of the actual contact areas (adhesive component). This is accompanied by the deformation of irregularities (deformation component), which causes their stress state. Therefore, heat release during friction is caused, on the one hand, by the destruction of adhesive bonds in the actual contact zones, and on the other hand - by the stress-strain state of microroughnesses. The choice of metal friction elements of different types of brake devices is mainly due to the level of energy load and operating conditions of the brakes. During braking, currents are generated and heat is accumulated in the surface layers of the working parts of the friction unit. These processes cause the greatest changes in the subsurface layers of friction pads. In the process of plastic deformation in materials, their structure and properties change. At the same time, the mechanical, dynamic and temperature gradients in the surface layers of metal-polymer friction pairs, the level of which depends on the braking modes, are constantly changing. In real conditions, metal-polymer friction pairs are subjected to the following thermal loads: pulse heating and slow natural cooling; heating and cooling at a high rate; slow heating and forced cooling; heating and cooling at a low rate. The rates of heating, natural and forced cooling of the working surfaces of metal-lopolymer friction pairs of brake devices are determined by their electrothermally stimulated processes of polarization and depolarization. [ABSTRACT FROM AUTHOR]

As species struggle to cope with rising ocean temperatures, temperate marine assemblages are facing major reorganization. Many benthic species have a brief but critical period dispersing through the plankton, when they are particularly susceptible to variations in temperature. Impacts of rising temperatures can thus ripple through the population with community‐wide consequences. However, responses are highly species‐specific, making it difficult to discern assemblage‐wide patterns in the life histories of different fish species.Here, we evaluate the responses to temperature in the early life histories of several fish species using otolith reconstructive techniques. We also assess the consequences of future warming scenarios to this assemblage.We sampled recent settlers of nine common species across a temperature gradient in the Mediterranean Sea and obtained environmental data for each individual. Using otolith microstructure, we measured early life traits including pelagic larval duration (PLD), growth rate, settlement size, hatching and settlement dates. We used a GLM framework to examine how environmental variables influenced early life‐history parameters.We show that increasing temperature results in considerable reduction in the dispersal potential of temperate fish. We find a nearly universal, assemblage‐wide decline in pelagic larval duration (PLD) of between 10% and 25%. This was because, with increasing temperature, larvae grew quicker to their settlement size. Settlement size itself was less affected by temperature and appears to be an ontogenetically fixed process.Given current estimates of ocean warming, there could be an assemblage‐wide reduction in larval dispersal of up to 50 km across the Mediterranean, reducing connectivity and potentially isolating populations as waters warm. [ABSTRACT FROM AUTHOR]