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Photovoltaic (PV)-based solar chimneys could assist stack ventilation within a large space hall. This study considered a comprehensive office building with a PV-based solar chimney as a case study to explore measures for enhancing stack ventilation. A computational fluid dynamics (CFD) model was established, and the influences of the inner heat source, chimney inlet position, solar heat gain and photovoltaic (PV) arrangement on the ventilation rate were investigated. The results revealed that PV-based solar chimneys could assist stack ventilation and would effectively provide a suitable indoor environment for occupied areas during the transitional season. Raising the chimney inlet position is conducive to improving the ventilation rate and cooling performance. The increase in the inlet position from a height of 0.2 m to 3.8 m would increase the ventilation rate up to 5%. The heat gain from the PV backside is an important method of enhancing the ventilation rate. A 200 W/m2 heat gain can lead to a 16.4% increase in ventilation. Moreover, the lower the heat source location, the higher the ventilation efficiency. This study provides basic strategies for optimising design schemes to improve natural ventilation efficiency. [ABSTRACT FROM AUTHOR]

The relationship between the volumetric thermodynamic coefficients of liquid metals at the melting point and interatomic bond energy was studied. Using dimensional analysis, we obtained equations that connect cohesive energy with thermodynamic coefficients. The relationships were confirmed by experimental data for alkali, alkaline earth, rare earth, and transition metals. Cohesive energy is proportional to the square root of the ratio of melting point Tm divided by thermal expansivity αp. Thermal expansivity does not depend on the atomic size and atomic vibration amplitude. Bulk compressibility βT and internal pressure pi are related to the atomic vibration amplitude by an exponential dependence. Thermal pressure pth decreases with an increasing atomic size. Fcc and hcp metals with high packing density, as well as alkali metals, have the relationships with the highest coefficient of determination. The contribution of electrons and atomic vibrations to the Grüneisen parameter can be calculated for liquid metals at their melting point. [ABSTRACT FROM AUTHOR]

The ventilation rate of a greenhouse is one of the major factors to consider when assessing its ventilation performance. Compared with plain areas, high-altitude areas have lower air pressure, thinner air, and stronger solar radiation, which in turn affect the magnitude of the local greenhouse ventilation rate. This paper is based on the use of online monitoring and computational fluid dynamics (CFD) techniques for modeling and model validation. The average relative error (ARE), mean absolute error (MAE), root-mean-square error (RMSE), and determination coefficient (R2) of the temperature were 4.88%, 1.396 °C, 1.428 °C, and 0.9982, respectively. The ARE, MAE, RMSE, and R2 of the velocity were 9.525%, 0.035 m/s, 0.049 m/s, and 0.9869, respectively. Then, the distributions of the wind pressure, Reynolds number (Re), thermal pressure, air density, air speed, and temperature in greenhouses in high-altitude and plain areas were researched to obtain the relevant factors affecting the ventilation rates of greenhouses in high-altitude areas. In addition, correlation analyses were conducted for five variables affecting the ventilation rate: the inlet velocity, the temperature difference between the inside and outside of the greenhouse, the air density difference between the inside and outside of the greenhouse, total indoor radiation, and the internal heat source of the crop, and the coefficients of their correlations with the greenhouse ventilation rate were 1.0, −0.83, −0.72, −0.72, and 0.68, respectively. A natural ventilation rate model for plateau areas was developed, with the ARE, RMSE, and R2 between the sample values and fitted values determined to be 4.55%, 0.543 m3/s, and 0.9997, respectively. The model was validated by predicting the greenhouse ventilation rate in winter (3 January 2022), and the ARE, RMSE, and R2 of the sample values and predicted values were 9.726%, 8.435 m3/s, and 0.9901, respectively. This study provides a theoretical basis for further research on greenhouse ventilation characteristics in high-altitude areas. [ABSTRACT FROM AUTHOR]

The primary objective of this research is to study the bearing performance characteristics having different operating conditions. Experimental investigations are carried out on phosphorous bronze hydrodynamic journal bearing with a surface textured at different loading conditions with multi-grade oil as lubricating at different constant rotational speeds (i.e.,1000 to 4000 rpm) for studying the dynamic characteristics. Results reported that oil film pressure and temperature distribution profile obtained experimentally are in good agreement with the theoretical results. Fuzzy-based Taguchi optimisation has been used in this experimental analysis to predict the optimal input parameters, which result in the optimal combination of temperature and reported that the oil film pressure and temperature distribution profile obtained experimentally are in good agreement the theoretical results. This analysis also attempts to describe the application of the fuzzy logic-based Taguchi analysis to optimise the performance parameters. [ABSTRACT FROM AUTHOR]

The ventilation rate of a greenhouse is one of the major factors to consider when assessing its ventilation performance. Compared with plain areas, high-altitude areas have lower air pressure, thinner air, and stronger solar radiation, which in turn affect the magnitude of the local greenhouse ventilation rate. This paper is based on the use of online monitoring and computational fluid dynamics (CFD) techniques for modeling and model validation. The average relative error (ARE), mean absolute error (MAE), root-mean-square error (RMSE), and determination coefficient (R2) of the temperature were 4.88%, 1.396 °C, 1.428 °C, and 0.9982, respectively. The ARE, MAE, RMSE, and R2 of the velocity were 9.525%, 0.035 m/s, 0.049 m/s, and 0.9869, respectively. Then, the distributions of the wind pressure, Reynolds number (Re), thermal pressure, air density, air speed, and temperature in greenhouses in high-altitude and plain areas were researched to obtain the relevant factors affecting the ventilation rates of greenhouses in high-altitude areas. In addition, correlation analyses were conducted for five variables affecting the ventilation rate: the inlet velocity, the temperature difference between the inside and outside of the greenhouse, the air density difference between the inside and outside of the greenhouse, total indoor radiation, and the internal heat source of the crop, and the coefficients of their correlations with the greenhouse ventilation rate were 1.0, −0.83, −0.72, −0.72, and 0.68, respectively. A natural ventilation rate model for plateau areas was developed, with the ARE, RMSE, and R2 between the sample values and fitted values determined to be 4.55%, 0.543 m3/s, and 0.9997, respectively. The model was validated by predicting the greenhouse ventilation rate in winter (3 January 2022), and the ARE, RMSE, and R2 of the sample values and predicted values were 9.726%, 8.435 m3/s, and 0.9901, respectively. This study provides a theoretical basis for further research on greenhouse ventilation characteristics in high-altitude areas.

The present study aims to study the thermohydrodynamic performance of noncircular journal bearings lubricated with multigrade oil. Experimental investigations are carried out on phosphorous bronze hydrodynamic journal bearing with a surface textured at different loading conditions with multigrade oil (MAK 2T oil) as lubricant at different constant rotational speeds (i.e., 1000-4000 rpm) for studying the dynamic characteristics. The journal-bearing's thermodynamic behavior is analyzed by simplifying modified Reynolds and energy equations to obtain surface-textured bearing performance characteristics, such as load-carrying capacity, mass flow rate, and power loss. The noncircular bearings suggest several design parameters, such as a tilt angle for designers. By considering thermal effects for MAK 2T oil lubricant, the requirements of a specific application can be fulfilled. [ABSTRACT FROM AUTHOR]

The primary objective of this research is to study the bearing performance characteristics having different operating conditions. Experimental investigations are carried out on phosphorous bronze hydrodynamic journal bearing with a surface textured at different loading conditions with multi-grade oil as lubricating at different constant rotational speeds (i.e.,1000–4000 rpm) for studying the dynamic characteristics. Results reported that oil film pressure and temperature distribution profile obtained experimentally are in good agreement with the theoretical results. Fuzzy-based Taguchi optimization has been used in this experimental analysis to predict the optimal input parameters, which result in the optimal combination of temperature and reported that the oil film pressure and temperature distribution profile obtained experimentally, are in good agreement the theoretical results. This analysis also attempts to describe the application of the fuzzy logic-based Taguchi analysis to optimize the performance parameters.

Thermal pressure is an inevitable thermodynamic consequence of heating a volumetrically constrained sample in the diamond anvil cell. Its possible influences on experimentally determined density‐mineralogy correlations are widely appreciated, yet the effect itself has never been experimentally measured. We present here the first quantitative measurements of the spatial distribution of thermal pressure in a laser‐heated diamond anvil cell (LHDAC) in both olivine and AgI. The observed thermal pressure is strongly localized and closely follows the distribution of the laser hotspot. The magnitude of the thermal pressure is of the order of the thermodynamic thermal pressure (αKTΔT) with gradients between 0.5 and 1.0 GPa/10 μm. Remarkably, we measure a steep gradient in thermal pressure even in a sample that is heated close to its melting line. This generates consequences for pressure determinations in pressure‐volume‐temperature (PVT) equation of state measurements when using an LHDAC. We show that an incomplete account of thermal pressure in PVT experiments can lead to biases in the coveted depth versus mineralogy correlation. However, the ability to spatially resolve thermal pressure in an LHDAC opens avenues to measure difficult‐to‐constrain thermodynamic derivative properties, which are important for comprehensive thermodynamic descriptions of the interior of planets. Plain Language Summary: The primary window into the interior of the Earth below ~10‐km depth are earthquake waves that give us a three‐dimensional elasticity/density image of the planet. In order to translate this into a geological model of the Earth, we need to know the physical and chemical response of rocks with the composition of the Earth's interior at high pressures and temperatures. This is achieved by experiments in which samples are subjected to the high pressures and temperatures of the deep Earth using laser‐heated diamond anvil cells. A long‐standing problem of such experiments is a hard to quantify pressure term caused by the heating of the sample. This paper, for the first time, experimentally quantifies the spatial distribution of thermal pressure in a typical experiment and explores the effect of its incomplete knowledge on the deduced mineralogical composition of the Earth. Key Points: Thermal pressure and its gradient in a diamond anvil cell have been measured and found close to the magnitude expected based on the thermodynamic limitThe observed gradients in thermal pressure are very steep. This can lead to an underestimation of the real pressure experienced by a heated sampleUnderestimating the thermal pressure by only 20% can have a significant effect on inferred deep mantle iron content derived from laser‐heated diamond anvil cell experiments [ABSTRACT FROM AUTHOR]

Dealing with buoyancy-driven flow to reduce infiltration heat is challenging for buildings such as cold storages where the indoor-outdoor temperature differences are significant. In this study, a segmented recirculating horizontal air curtain (SRHAC) is proposed to respond to the vertical thermal buoyancy profile in doorways and recover the cold air entrained by the air curtain. Specifically, SRHAC is a planar turbulent impingement jet discharged through a vertically mounted rectangular nozzle. The discharge nozzle is divided into segments and the return vent recirculates the discharged air to the rear of the discharge nozzle. In this study, the aerodynamic sealing performance of the SRHAC is investigated by considering structural, operational, and ambient parameters. Orthogonal analysis reveals the flow rate, nozzle width, and discharge angle as significant factors affecting the thermal separation efficiency of the SRHAC. Increasing the flow rate and decreasing the nozzle width leads to an increase in the jet momentum flux, thereby enhancing the thermal separation efficiency, with a maximum efficiency of 75.9 %. Setting the discharge parameters in the three sections along the height improves the thermal separation efficiency by 16.5% points. The maximum efficiencies of two-, three-, and five-segment air curtains are 83.6 %, 87.3 %, and 90.3 %, respectively. The separation efficiency of the SRHAC remains relatively stable even when the indoor-outdoor temperature difference varies between 32 and 57 K. These results establish that the SRHAC is an efficient energy-saving device, with the ratio of reduced infiltration load to energy consumption as high as 110.9. [Display omitted] • Segmented recirculating horizontal air curtain (SRHAC) was proposed for thermal separation. • Key impact factors based on ANOVA: flow rate, nozzle width, segmented discharge angle. • The thermal separation efficiency of five-segment SRHAC reaches 90.3 %. • SRHAC efficiency remains stable against temperature fluctuations. [ABSTRACT FROM AUTHOR]

Abstract The understanding of heat and mass transfer phenomena and underlying flow and thermal mechanisms in a tunnel fire is critical for smoke control and human evacuation. Critical velocity has been acknowledged as the most critical parameter to guarantee the effectiveness of smoke control using longitudinal ventilation in tunnels. However, in slopping tunnels, even under the conditions where the expected smoke flow route and the corresponding critical velocity can be achieved, another flow pattern which has an opposite smoke flow direction and higher gas temperatures is also likely to be generated. This phenomenon has not attracted enough attention. In this paper, multiple patterns of heat and mass flow in a slopping tunnel induced by the competition of buoyancy and forced ventilation were examined using laboratory experiments, Computational Fluid Dynamics simulations and theoretical analysis. Both dynamic and steady state analyses were performed to explain the transient evolution behaviors and final steady solutions for these flow patterns. The constraints and the prerequisite conditions for the existence of multiple flow patterns or only a certain pattern were expressed in terms of three main influencing parameters including fire heat release rate, pressure rise induced by mechanical ventilation system and the fire source location. For the regime where both fan-dominated and buoyancy-dominated patterns can occur, the initial flow state and the flow evolution process determines the steady state solutions, indicating the activation time of the mechanical ventilation plays an important role in the final flow pattern. This study has particular relevance to understanding the complex heat and mass flow behaviors in a sloping tunnel fire and it provides new implications for smoke control. [ABSTRACT FROM AUTHOR]

In the present simulation study, the performance characteristics of vertical offset non-circular journal bearing have been evaluated. During study, the thermal pressures have been found of increasing nature with increase in speed in both the lobes of the bearing. A considerable rise in oil-film temperature and thermal pressure has been found in lower lobe and comparatively a low rise in oil-film temperature and thermal pressures has been found in upper lobe of the bearing. The trend for variation of oil-film temperature with speed has been found of increasing nature. The load capacity, power loss in the bearing and bearing characteristics Sommerfeld number has been observed to be of increasing nature with speed. It has been concluded that more than one lobe have been reported in the bearing profile under study, thus the profile can be considered as an alternate to circular journal bearing for better stability applications.

Tunnels are of key importance to the ventilation network in underground buildings. For sloping tunnels, the effect of thermal pressure on the underground ventilation system has not been clarified in the existing research. A field test in an underground sloping tunnel was carried out and the results showed that the temperature decreases in the form of exponent. Based on an exponential model of temperature decrease, an equation to predict thermal pressure is proposed for sloping underground tunnels. Four factors on the thermal pressure, surface roughness of the tunnel wall, air velocity, dimensions of the underground tunnel and temperature difference between the air and the tunnel wall are discussed in detail. Surface roughness of the tunnel wall, air velocity and dimensions of the tunnel have been found having little impact on the thermal pressure efficiency when the tunnel is beyond the length of L min . The temperature difference between the air and the tunnel wall is the main factor on the thermal pressure efficiency. A simplified method is recommended to calculate the thermal pressure for sloping underground tunnels. [ABSTRACT FROM AUTHOR]

The paper presents the emergence of thermoelastic distortions at the contact of the drum with the brake shoe from a vehicle. The critical sliding speed is determined, assuming the existence of small initial sinusoidal undulations and their growth. For higher speeds than the critical speed, the size of the 'hot-spots' expands at different rates. It is also taken into consideration the influence of wear rate on the size of the 'hot-spot' surface. [ABSTRACT FROM AUTHOR]

A new correlation function for the calculation of viscosity for five typical supercritical gases is presented using the rainwater-Friend and modified Enskog theory. It is shown that by using accurate value for the thermal pressure and co-volume in the modified Enskog theory, this correlation function is suitable for calculation of the viscosity of supercritical gases, without any density and temperature limitation. For this purpose, two new correlation functions for the calculation of the thermal pressure coefficient and co-volume are presented. It is also shown that the co-volume in the modified Enskog theory depends not only on temperature, but also on density. The accuracy of the calculated viscosity is about 1%, which is much better than the previous work. It is also shown that the modified Enskog theory can be extended to very high density-temperature ranges by choosing correct values for the thermal pressure and co-volume.

In order to analyze the influence of opening area ratio on natural ventilation in city tunnel under block transportation, dimensionless analysis, model experiment and CFD (computational fluid dynamics) simulation are used to evaluate the velocity distribution, temperature distribution and the pollutants concentration. The similarity criterion of thermal-pressure ventilation and proportional constant of the heat with the same temperature distribution are obtained by the dimensionless analysis about the thermal buoyancy and gravity of the most adverse section at block transportation. According to the similarity conditions, several groups of model experiments and computer models are built. Results of the model experiments and CFD simulations show that with the increase of opening area ratio, the effect of the natural ventilation improves at the beginning, but as opening area ratio continues to increase, the role of natural wind pressure outside tunnel is strengthened. There are some uncertainties of the natural wind pressure which might lead to the ventilation effect decline. With the increase of opening area ratio, the construction cost of vent shaft increases observably at the same time. So it is of great significance for city tunnel to choose an appropriate opening area ratio which can meet the requirements of ventilation under the block transportation without superfluous cost of blindly increasing opening area ratio investment. [ABSTRACT FROM AUTHOR]

• The distributions of temperature and air velocity for a curved double-skin façade (CDSF) were investigated. • The nonuniformity of solar irradiation on a curved surface is higher than that of a planar surface. • The thermal pressures of a CDSF show different values at different positions. • Solar irradiances show a power function relationship with the air velocity. • There should be transverse flows and heat transfers in the cavity of a CDSF. Curved architectural forms are becoming popular in modern building designs, resulting in more demanding requirements of curved double-skin façades (CDSF). However, CDSF's natural ventilation performance is barely known, as most current studies investigate planar DSF (PDSF). This paper experimentally evaluated the thermal performance of a reduced scale CDSF model. Experimental results show that CDSF can form natural ventilation by buoyancy, however, with significant discrepancies in the distribution of solar irradiances on the curved surface. Observed nonuniformity shows 30.05 % on average vertically and 9.12 % on average horizontally. The thermal pressures vary at different horizontal positions with a fluctuation range between 0.056 Pa and 0.063 Pa, indicating the influence of gradients and the existence of transverse flows and heat transfers in the cavity. Moreover, the effects of solar irradiation and outdoor air temperature on the CDSF are discussed. The results show that solar irradiation is the main influencing factor on the thermal performance of a CDSF, which are correlated with air velocities in the form of power functions. The influence of solar irradiation on CDSF is similar to that of PDSFs, but CDSF exhibits a bigger exponent. In comparison, outdoor air temperature shows very limited effects, and the influence of outdoor air temperature on CDSF is similar to that of PDSF. For the analyzed CDSF, the thermal pressures only fluctuate from 0.053 Pa to 0.055 Pa when the outdoor air temperature raises from 24 °C to 36 °C. [ABSTRACT FROM AUTHOR]

We have presented an analysis of the volume expansion data for periclase (MgO), lime (CaO), corundum (AlO) and spinel (MgAlO) determined experimentally by Fiquet et al () from 300K up to 3000K. The thermal equation of state due to Suzuki et al () and Shanker et al () are used to study the relationships between thermal pressure and volume expansion for the entire range of temperatures starting from room temperature up to the melting temperatures of the solids under study. Comparison of the results obtained in the present study with the corresponding experimental data reveal that the thermal pressure changes with temperature almost linearly up to quite high temperatures. At extremely high temperatures close to the melting temperatures thermal pressure deviates significantly from linearity. This prediction is consistent with other recent investigations. A quantitative analysis based on the theory of anharmonic effects has been presented to account for the nonlinear variation of the thermal pressure at high temperatures. [ABSTRACT FROM AUTHOR]

Abstract: The analysis of energetic particles and magnetic field measurements from the Ulysses spacecraft has shown that in a series of events, the energy density contained in the suprathermal tail particle distribution is comparable to or larger than that of the magnetic field, creating conditions of high-beta plasma. In this work we analyze periods of high-beta suprathermal plasma occurrences (βep >1) in interplanetary space, using the ratio (βep ) of the energetic particle (20keV to ∼5MeV) and magnetic field energy densities from measurements covering the entire Ulysses mission lifetime (1990–2009) in order to reveal new or to reconfirm some recently defined interesting characteristics. The main key-results of the work are summarized as follows: (i) we verify that high-beta events are detected within well identified regions corresponding mainly to the vicinity of shock surfaces and magnetic structures, and associated with energetic particle intensity enhancements due to (a) reacceleration at shock-fronts and (b) unusually large magnetic field depressions. (ii) We define three considerable features for the high-beta events, concentrated on the next points: (a) there is an appreciable solar-activity influence on the high-beta events, during the maximum and middle solar-cycle phase, (b) the annual peak magnitude and the number of occurrences of high events are well correlated with the sunspot number, (c) the high-beta suprathermal plasma events present a spatial distribution in heliographic latitudes (HL) up to ∼±80°, and a specific important concentration on the low (−25°⩽HL<−6°, 6°1) events are characterized by a very large parameter βep (up to 1732.5), a great total duration (406days) and a large percentage of the Ulysses-mission lifetime (which is equal to 6.34% of the total duration with usable measurements, and 11.3% of the duration in presence of suprathermal particles events). [Copyright &y& Elsevier]

Abstract: A comparative study based on the thermal performance of elliptical and offset-halves journal bearings has been carried out by solving energy equation while assuming Parabolic Temperature Profile Approximation across the fluid film for faster computation of temperatures. Investigation for the rise in oil film temperatures, thermal pressures, load capacity, and power loss for three commercially available grade oils have been carried out for bearing configurations under study. It has been found that the offset-halves journal bearing runs cooler when compared with elliptical journal bearing profile with minimum power loss and good load capacity using Oil 2 as lubricant for which minimum thermal degradation has been observed. [Copyright &y& Elsevier]

Abstract: We directly probed the phonon density of states (DOS) of hexagonal close-packed iron (ε-Fe) with high statistical quality between pressures of 30GPa and 151GPa using nuclear resonant inelastic X-ray scattering and in situ synchrotron X-ray diffraction experiments at 300K. From each measured phonon DOS, we determined the vibrational free energy (Fvib ) and mean-square displacement of atoms, 〈u 2〉. The volume dependence of Fvib is directly related to the vibrational thermal pressure, which we combine with previously reported theoretical values for the electronic and anharmonic thermal pressures to find the total thermal pressure (Pth ). In addition, we obtained the shape of ε-Fe’s melting curve from the volume dependence of our 〈u 2〉, and anchored it with an experimentally determined melting point to obtain the high-pressure melting behavior of ε-Fe. Considering thermal pressure and anharmonic effects, we found ε-Fe’s melting temperature at the pressure of Earth’s core–mantle boundary (P =135GPa) to be 3500±100K. Extrapolating our melting curve to the pressure of the inner-core boundary (ICB, P =330GPa), where Earth’s solid inner-core and liquid outer-core are in contact, we determined a melting temperature for ε-Fe of 5600±200K. Finally, combining this temperature constraint with our Pth , we determined the density of ε-Fe under ICB conditions to be 13.50±0.03g/cm3, which is 5.5±0.2% higher than the seismically inferred density at the ICB. [Copyright &y& Elsevier]

Abstract: Thick YSZ ceramic coatings were prepared by thermal pressure and filtration of sol–gel paint (TPFSP), a modified sol–gel composite coating technique. SEM results show that the coatings were dense and crack-free by using paints of high mass ratios of YSZ powder to Zr–Y oxide in sol and high pressures. And the cross-sectional detail of coatings exhibited that the microstructure was consisted of micro/nano-size ceramic particles and micro-pores. The thermal insulation tests indicated that mass ratio of YSZ powder to Zr–Y oxide in sol was in inversely linear relationship with temperature drop per micron thickness. The coating showed good adherence with alloy substrate and maintained structural integrity when exposed at 1050°C for 200h. The cyclic oxidation test also indicated that both of oxidation resistance and spallation resistance for YSZ coated specimens were greatly improved. The TPFSP process could be a promising method to prepare TBCs for wide applications. [Copyright &y& Elsevier]

The ratio of the plasma pressure to the magnetic field pressure (or the ratio of their energy densities)—plasma parameter “beta” (\beta) —is critical in determining the dynamics of the interaction of the solar wind with planetary magnetospheres and has important implications to the propagation of energetic particles and to the structure of the shocks. In the interplanetary space, the value of “beta” is usually in the range of 0.1–1.0, and the contribution of the superthermal particles to the plasma pressure is generally assumed negligible. However, the analysis of energetic particles and magnetic field measurements by the Ulysses spacecraft shows that, in a series of events, the energy density contained in the superthermal tail of the particle distribution is comparable to or even higher than the one of the magnetic field, creating conditions of high-beta plasma. In this paper, we extensively survey and analyze measurements of the energy density ratio (parameter \betaep) of the energetic particles (20 keV–5 MeV) to the magnetic fields by Ulysses, for its entire trajectory (1990–2009), in order to find occurrences of high-beta ( \betaep > 1) superthermal plasma conditions. As expected, periods of dominant magnetic energy were observed most of the time, for the above mentioned particle energy range. Nevertheless, a number of 484 distinct periods with a total duration of 406.02 days were identified when the energy density carried by the energetic ions overwhelmingly dominated that of the magnetic field. These interplanetary high-beta (\betaep > 1) events are characterized by a very high parameter \betaep (up to \sim1733), a great total duration (of 406.02 days), and a large percentage (11.3%) of the total mission lifetime (in presence of energetic particle events). Furthermore, these events were detected within well-identified regions corresponding mainly to the following: 1) the vicinity of shock fronts; 2) the vicinity of large transient disturbances associated with shock waves; 3) filamentary magnetic structures; and 4) the vicinity of the Jovian magnetospheric environment. These events were also associated with energetic particle intensity enhancements due to the following: 1) reacceleration at interplanetary corotating interaction regions (CIRs), solar flare (blast), transient, and/or CME-driven shocks; 2) unusually large magnetic field depressions; 3) Jupiter's bow shock particle acceleration; and 4) leakage from Jupiter's magnetosphere. [ABSTRACT FROM AUTHOR]

Abstract: Thermohydrodynamic study for the analysis of elliptical journal bearings has been presented in the present work for three different grade oils commercially available. Finite difference method has been adopted for numerical solution of the Reynolds and energy equation. Temperature in the oil film is computed using parabolic temperature profile approximation technique. A comparative study for rise in oil-temperatures, thermal pressures and load carrying capacity has been carried out. Comparison amongst three oils elucidates that the thermal degradation for oil 1 is the least, whereas the load carrying capacity for oil 3 is the highest. [ABSTRACT FROM AUTHOR]

Abstract: In order to represent the pressure dependent thermodynamic functions for phase diagram calculations, the thermal volume model extends the Swenson concept of thermal pressure which is independent of volume and varies linearly with temperature. The expressions for the thermodynamic potentials: enthalpy, Gibbs energy and their derivatives such as molar volume, thermal expansion and heat capacity are then deduced for non-magnetic solids. The phases considered are simple oxides and silicates of the Earth''s lower mantle under high pressure and high temperature. As a practical application, the thermodynamic functions of periclase are calculated and compared with available experimental data. A good agreement is achieved. [Copyright &y& Elsevier]

The present paper proposes a new empirical relationship to predict the values of volume dependence of the Gruneisen parameter. ε-Fe, NaCl, Li, Na and K in different pressure ranges have been employed to test the reliability of the model. The obtained results indicate that the model is reliable due to a good agreement between calculated results and the experimental data. Based on this modified model, the temperature dependence of thermal pressure for NaCl is also examined. [ABSTRACT FROM AUTHOR]

Abstract: In the present study, a relationship between thermal pressure and volume expansion ratio is disclosed for ionic solids at 1bar pressure. The ionic solids NaCl, KCl, MgO and CaO are considered for the analytic thinking. The analysis is based on the experimental data tabulated by Anderson and generalized data reported by Srivastava. A close agreement between the present study and the experiment reveals the validity of the present work. The extrapolated values of thermal pressure at higher temperatures are useful to understand the thermoelastic behaviour of solids. [Copyright &y& Elsevier]

Abstract: Evaluation of P–V–T differential properties such as internal pressure, thermal pressure and isothermal compressibility, is a critical test for any equation of state. Certainly, pressure and internal energy equations obtained from RDF theory are not excepted from this rule either. Internal pressure, thermal pressure and isothermal compressibility for a Lennard-Jones (LJ) fluid have been calculated using three known analytical expressions for radial distribution function (RDF) at different temperatures and densities and compared with the corresponding values of these properties obtained from molecular dynamics (MD) and two accurate equations of state for the LJ fluid. Until now, this approach has not been utilized to estimate these quantities. To calculate these quantities, the variation of radial distribution function (RDF) with density and temperature is required. Therefore, we should have analytical expressions which explicitly present RDF as a function of temperature, density and interparticle distance. It is shown that some of these expressions evaluate the values of these quantities well. [Copyright &y& Elsevier]

Abstract: In the present communication we have re-parametrized the thermodynamic and thermoelastic properties of NaCl at low compressions and high temperatures. It is found that the thermal expansivity and isothermal bulk modulus both change linearly with the increase in temperature at compressions down to 0.90. The present study reveals that the thermal pressure is nearly independent of compression along an isotherm. This is consistent with the earlier findings. [Copyright &y& Elsevier]

Abstract: The method for determining the thermal expansivity of hexagonal close-packed (HCP) iron at high pressure and high temperature developed by Isaak and Anderson [Physica B 328 (2003) 345] has been used taking the input parameters derived from the seismic data and the Stacey reciprocal K-primed equation of state [F.D. Stacey, and P.M. Davis, Phys. Earth Planet. Inter. 142 (2004) 137]. Values of thermal pressure have been obtained from the formulation presented by Shanker et al. [Phys. Earth Planet. Inter. 147 (2004) 333]. Pressure (P)–volume (V)–temperature (T) relationships and thermal expansivity for HCP iron at high P and high T are obtained. The results for thermal expansivity are found to compare well with the corresponding results derived by Isaak and Anderson using the laboratory data. [Copyright &y& Elsevier]

Abstract: In the present paper, the thermal pressure for the MgO is evaluated from room temperature to 3000K at atmospheric pressure with the help of data suggested by Jacobs and Oonk. Various relationships between thermal pressure and volume expansion ratio are examined. Thermoelastic properties viz. C 11, C 44, C S, and K S are calculated at high temperatures for the solid under study, with the help of Murnaghan and Tallon models. Predicted values of thermoelastic properties at higher temperatures can be used to understand the high-temperature behavior of MgO at 1bar pressure. [Copyright &y& Elsevier]

Abstract: The strongest crustal magnetic fields at Mars are located in certain regions in the Southern hemisphere and lead to the formation of large-scale mini-magnetospheres. In the Northern hemisphere, the crustal fields are rather weak and usually do not prevent direct interaction between the SW and an ionosphere/atmosphere. Exceptions occur in the isolated mini-magnetospheres formed by the crustal anomalies. Electron density profiles derived from radio occultation data obtained by the Radio Science Mars Global Surveyor (MGS) experiment have been compared with the crustal magnetic fields measured by the MGS Magnetometer/Electron reflectometer (MAG/ER) experiment. The effective scale-height of the electron density for two altitude ranges, 145–165km and 165–185km have been derived for each of the profiles studied. For the regions outside of the mini-magnetospheres the thermal pressure of the ionospheric plasma for the altitude range 145–185km has been derived. The pressure balance in the high latitude ionosphere at Mars has been studied. In the Northern hemisphere average pressure at the altitude 160km p 160 is practically independent of SZA. In the Northern hemisphere B 2/8π can exceed p 160 in half the cases at altitudes 170–180km, and magnetic forces can drive effective convection. In large scale mini-magnetospheres in the Southern hemisphere the ratio H 145–165/H 165–185 on average, larger and more variable than in the Northern hemisphere. This suggests that plasma convection at altitudes above 165km is effective. Within the Martian mini-magnetospheres plasma convection has to be primarily a drift of charged particles across the strong crustal magnetic fields and in this regard Martian mini-magnetospheres are similar to the terrestrial magnetosphere. [Copyright &y& Elsevier]

Estimates of core density deficit (cdd) of the Earth''s outer core recently reported by Anderson and Isaak [Another look at the core density deficit of Earth''s outer core, Phys. Earth Planet Int. 131 (2002) 19–27] are questionable in view of the serious errors in the pressure–volume and bulk modulus data due to an inadequacy in the calibration process used by Mao et al. [Static compression of iron to 300GPa and Fe0.8Ni0.2 alloy to 200GPa: implications for the core, J. Geophys. Res. 94 (1990) 21737–21742]. The data used by Anderson and Isaak deviate significantly from the corresponding values derived from seismology. In the present study we have used the input data on density, isothermal bulk modulus and its pressure derivative from Stacey and Davis [High pressure equations of state with application to lower mantle and core, Phys. Earth Planet Int. 142 (2004) 137–184] which are consistent with the seismological data. Volumes of hexagonal close-packed iron have been calculated at different temperatures under isobaric conditions at P = 330GPa, the inner core boundary (ICB) pressure using the relationship between thermal pressure and volume expansion based on the lattice potential theory originally due to Born and Huang [Dynamical Theory of Crystal Lattices, Oxford University Press, Oxford, 1954, p. 50]. The formulation for thermal pressure used by Anderson and Isaak has been modified by taking into account the variations of thermal expansivity α and isothermal bulk modulus KT with temperature. Values of cdd are then estimated corresponding to different temperatures ranging from 4000 to 8000K. The results for cdd at different temperatures obtained in the present study are significantly higher than those estimated by Anderson and Isaak suggesting that the cdd for the Earth''s outer core is nearly 10%. The effects of nickel when an Fe–Ni alloy replaces Fe are estimated and found to be insignificant. [Copyright &y& Elsevier]

Abstract: In the present paper we have studied the pressure–volume–temperature (P–V–T) relationship for MgO under high pressures and at high temperatures. We have used the basic thermodynamic formulation and a numerical method for evaluating the thermal pressure for MgO starting from room temperature (T=300K) up to its melting temperature (T=3000K). The volume–temperature relationships under isobaric conditions have been obtained and compared with the available experimental data based on density measurements. We make use of some important phenomenological forms of the equation of state such as (1) the Birch–Murnaghan EOS, (2) the Rydberg–Vinet EOS and (3) the Shanker EOS. Finally, we have determined the P–V–T relationship for MgO in the temperature range 300–3000K for pressures up to 224GPa. The results obtained in the present study are in good agreement with the available experimental data for predicting the pressure–volume relationship along different isotherms at selected temperatures. [Copyright &y& Elsevier]

A recent survey of the fine-structure excitation of neutral carbon reveals that the in- terstellar medium in the Galactic plane exhibits a thermal pressure, n T/ k, that ranges from about 10³ to 104cm-3K from one location to the next, with occasional excursions in excess of about 105cm-3K. The large excitations for small amounts of gas indicate that some regions are either subjected to shocks or must be pressurized within time scales much shorter than the time needed to reach thermal equilibrium. These rapid fluctuations probably arise from the cascade of macroscopic mechanical energy to small scales through a turbulent cascade. One consequence of this effect is that changes in gas temperature can arise from near adiabatic compressions and expansions, and this may explain why investigations of 21-cm emission and absorption reveal the presence of hydrogen at temperatures well below the expected values derived from the balance of various known heating and cooling processes. [ABSTRACT FROM AUTHOR]

An equation of state (EOS) recently formulated by Shanker and Kushwah has been used for calculating the volumes of molybdenum (Mo) and tungsten (W) at simultaneously elevated pressures and temperatures. The results are obtained up to a pressure of 300 GPa and up to a temperature of nearly 7000 K. The values of thermal pressure have been calculated using the formulation given by Anderson and Isaak which takes into account the effect of thermal excitation of electrons. The Shanker–Kushwah EOS has been found most suitable for the materials for which the pressure derivative of isothermal bulk modulus at P=0, i.e. K0′ is less than four. The solids Mo and W satisfy this condition. The values of volumes and isothermal bulk modulus calculated at different temperatures and pressures are found to present close agreement with the experimental data based on shock wave measurements reinforcing the validity of the equation of state used. The results based on the Shanker–Kushwah EOS are found to compare well with the corresponding values derived from the Vinet EOS. [Copyright &y& Elsevier]

A constraint adopted in several geochemical studies of core composition is that the core density deficit (cdd) is 10%, with the implication that this number is based on robust geophysical evidence. The cdd is the perceived difference between the density of pure iron at core conditions and the seismically-determined density of the outer core. The importance of the cdd is that it limits the concentration of allowable light elements, such as sulfur and silicon, which, when mixed with Fe, or an Fe–Ni alloy, comprise the geochemical model of the inner core.We present evidence that the value of 10% for the cdd of the outer core is too high. Using a thermal-pressure equation-of-state, we find that for assumed melting temperatures of pure iron at the inner–outer core (ICB) pressure of 330 GPa ranging from 7500 to 4800 K, the cdd ranges from 2.9 to 7%, respectively. Reports that the cdd value of the outer core is less than 10% are found in a number of shock-wave studies, but the values reported here are apparently the lowest. Our cdd value for an assumed melting temperature of 6000 K for iron at 330 GPa is 5.4% and is compatible with proposed concentrations of Si and S impurities found from solubility studies at high P and T. [Copyright &y& Elsevier]

• A fast numerical model for deep-buried underground tunnel ventilation is proposed. • The model uses the Z-transfer coefficient method considering air condensation. • The model greatly improves the calculation efficiency and accuracy. • The influence of air humidity on the accuracy of thermal pressure in the calculation model is evaluated. Deep-buried tunnels are widely used in underground space for transportation and air ventilation. Accurately predicting the heat and mass transfer process of the ventilation in a tunnel is conducive to the design optimization of air conditioning and utilization of thermal pressure for underground buildings. The air condensation process has an important impact on the variation of air parameters in the tunnel. The Z-transfer coefficient method cannot accurately calculate the air parameters when the air condensation process occurs. To resolve this problem, in this study, the computational domain is redefined and a fast calculation model is proposed for heat and mass transfer in a deep-buried underground tunnel. The calculation results of this model are in good agreement with the field test results. Moreover, when calculating the hourly parameters of ventilation for a year, the running time of the new model is less than half of the finite difference method model. Considering the hourly parameters of ventilation for a certain number of days, the new model has a higher calculation efficiency. In addition, a case study was conducted to demonstrate the significance of considering the air condensation process in the model. If the calculation results of the model considering air humidity and condensation are taken as a reference, the absolute error of air temperature at the tunnel exit and the relative error of the thermal pressure, calculated by the model ignoring air humidity, can respectively reach 1.94 °C and 34%. [ABSTRACT FROM AUTHOR]

Thermal-pressure Equations of State (EoS) such as the Mie-Grüneisen-Debye (MGD) model depend on several assumptions, including the quasi-harmonic approximation (QHA) and a simplified phonon density of states. We show how the QHA is violated by materials exhibiting anisotropic thermal pressure. We also show that at pressures lower than those of the isochor of the reference volume, the static pressure may become sufficiently negative to make the compressional part of the EoS invalid. This limit is sensitive to the combined effects of the EoS parameters K'0, q and the Grüneisen parameter γ0. Large values of q, which correspond to a rapid decrease in phonon mode frequencies with increasing volume, can also lead to the bulk modulus becoming zero at high pressures and temperatures that are not particularly extreme for planetary geotherms. The MGD EoS therefore has an extremely limited P and T regime over which it is both valid and has physically-meaningful properties. Outside of this range, additional terms should be included in the thermal pressure that represents the physical properties of the solid. Or, alternatively, 'isothermal' EoS in which the temperature variation of the elastic properties is explicitly modeled without reference to a physical model can be used. [ABSTRACT FROM AUTHOR]

Abstract: Singh and Kumar have questioned the validity of the Mie–Grüneisen equation using an incorrect formulation. The Suzuki equation for thermal expansivity has been expressed by them in terms of thermal pressure using a wrong definition. The formulations already reported in the literature have been rediscovered by them and redesignated as the Kumar formulation. In the present communication we have reinforced the validity of the Mie–Grüneisen EOS using the correct definition of thermal pressure in the Suzuki formulation. [Copyright &y& Elsevier]