Volumetric Expansion Coefficient Research Articles

Thermometry mapping during CT-guided thermal ablations: proof of feasibility and internal validation using spectral CT

Objective. Conventional computed tomography (CT) imaging does not provide quantitative information on local thermal changes during percutaneous ablative therapy of cancerous and benign tumors, aside from few qualitative, visual cues. In this study, we have investigated changes in CT signal across a wide range of temperatures and two physical phases for two different tissue mimicking materials, each. Approach. A series of experiments were conducted using an anthropomorphic phantom filled with water-based gel and olive oil, respectively. Multiple, clinically used ablation devices were applied to locally cool or heat the phantom material and were arranged in a configuration that produced thermal changes in regions with inconsequential amounts of metal artifact. Eight fiber optic thermal sensors were positioned in the region absent of metal artifact and were used to record local temperatures throughout the experiments. A spectral CT scanner was used to periodically acquire and generate electron density weighted images. Average electron density weighted values in 1 mm3 volumes of interest near the temperature sensors were computed and these data were then used to calculate thermal volumetric expansion coefficients for each material and phase. Main results. The experimentally determined expansion coefficients well-matched existing published values and variations with temperature—maximally differing by 5% of the known value. As a proof of concept, a CT-generated temperature map was produced during a heating time point of the water-based gel phantom, demonstrating the capability to map changes in electron density weighted signal to temperature. Significance. This study has demonstrated that spectral CT can be used to estimate local temperature changes for different materials and phases across temperature ranges produced by thermal ablations.

Modelling of flue gas injection and collaborative optimization of multi-injection parameters for efficient coal-based carbon sequestration combined with BP neural network parallel genetic algorithms

Cooperative equalization among the injection parameters can control the economic objective function to ensure the efficiency of gas-mixture-enhanced coalbed methane recovery (GM-ECBM). This study first proposed and validated a refined thermal-hydro-mechanical-chemical (THMC) coupling model with a convenient permeability model. Based on GM-ECBM numerical calculation results under different combinations of injection parameters, different types of cost-income objective functions, including different costs and incomes, were optimized by parallelly applying a genetic algorithm and backpropagation neural network (GA-BP). Using the recovery rate as the index, a small inter-well distance and a large injection pressure can increase the optimal CO2 proportion. The effectiveness of enhancing the injection temperature was significantly correlated with both inter-well distance and the injection pressure. Cooperative equalization among the injection parameters can explain different viewpoints of different scholars on the temperature effect. Large Henry’s law constants resulted in low carbon sequestration and coalbed methane (CH4) production but did not affect the optimal CO2 proportion. High carbon sequestration and CH4 prices corresponded to small inter-well distances and large injection pressure. Based on the objective function, the optimal inter-well distance and the injection temperature were 175–220 m and 305.5–311.5 K, respectively. The volumetric adsorption-induced expansion coefficient (VAEC) of CO2 determined the optimal CO2 proportion, the optimization feasibility of the injection scheme, and the applicability of GM-ECBM.

Deep learning-based extraction and quantification of features in XCT images of steel corrosion in concrete

The corrosion of rebars in concrete has been regarded as one of the most predominant factors for the degradation of reinforced concrete (RC) structures. The accurate predictions of corrosion damages are the basis for the safety assessment of in-service RC structures and the enhancement of new structure designs. X-ray computed tomography (XCT), known for its non-destructive capabilities, has been widely utilized to understand the corrosion process inside the concrete, offering three-dimensional (3D) visualization and aiding in the identification of the parameters in the predictive model of steel corrosion. This study uses U-Net, a deep learning network, to detect various phases of steel corrosion evolution in concrete, including the identification of rebar, corrosion products, pores, cement mortar, and corrosion-induced cracking. A galvanostatic accelerated corrosion test was conducted to simulate rebar corrosion within the mortar. The XCT test was performed, producing a series of XCT images that revealed the corrosion-induced cracks in the concrete. This set of images formed a comprehensive training database for the U-Net model. The performance of the model was significantly improved by data augmentation within the training dataset, thereby enabling it to recognize corrosion-induced cracking and pores. The U-Net model proved effective in accurately segmenting the XCT images into different phases, demonstrating a high accuracy rate of 99.18% on the validation dataset. A mean Intersection over Union (IoU) of 82.1% and a mean F1 score of 89.1% are observed on the test dataset, showing superior segmentation performance on XCT images. This significant advancement has automated the process of visualizing and 3D reconstructing the steel corrosion process inside the concrete. Concurrently, it has enabled the quantification of the volumetric expansion coefficient of corrosion products. The findings reveal spatial and temporal variations in this coefficient due to the migration of the corrosion product through the cracks.

Use of geothermal energy to prevent road pavement icing and damage in cold climate areas

In cold climate or alpine regions, freezing temperatures and snow can result into road icing, with consequent threat of the circulation security (Figure 1(a)). When the road surface temperature goes below zero, not only the road surface ices, but also the soil below the pavement can undergo freezing. The phenomenon of soil freezing is complex due to the multi-phase and porous nature of the soil itself. Generally speaking, as ice expands in the soil pores, the soil volume increases (of about 9%, depending on the soil porosity and water saturation). This can induce frost heaving, with consequent damage of the road pavement. In this framework, the possibility to use geothermal energy systems embedded in tunnel linings for road pavement de-icing has rarely been investigated. In such systems, the concrete tunnel lining is equipped with a circuit of pipes, in which a heat carrier fluid circulates and exchanges heat with the ground. As the rock or soil around the tunnel is generally hotter than the external air temperature, heat is extracted from the rock or soil to the fluid, transported through the pipes circuit outside the tunnel, and used to de-ice the pavement road.
 The objective of this study is to go a step forward in the investigation of this innovative application, for both road de-icing and prevention of frost heave. A portion of a geothermally activated tunnel and its connection to a road pipe circuit was simulated numerically (Figure 1 (b)). Appropriate climatic conditions were considered as boundary conditions at the surface level and inside the tunnel, according to available data. The efficiency of the technology was investigated under different climatic and exploitation scenarios. Figure 1 (c) shows as an example the thermal field obtained after the activation of the geothermal plant. The evolution of temperature on the road pavement surface and at the road pipes depth (30 cm from the road pavement surface) are presented on Figure 2 (a), together with the evolution of the external air and tunnel temperature, imposed as boundary conditions according to the monitored climatic conditions in the city of Oslo [1].
 The geothermal system was activated after two years of simulation, by changing the fluid pipes velocity from 0 (non active system) to 0.9 m/s (purple curve on the right axis on Figure 2 (a)). The results show that the road temperature increases thanks to the activation of the system (i.e. when the fluid pipes velocity is imposed to 0.9 m/s).
 Furthermore, a recently developed thermo-hydro-mechanical constitutive model for frozen soils [2] was used to quantify the soil heave due to freezing, with and without the activation of the geothermal system. For this purpose, a similar numerical model has been developped where a column of saturated soil below the road and the tunnel were modelled. The phreatic water table is at the ground surface level and gravity as well as the geostatic stress conditions are considered. The soil is a clay with a low hydraulic conductivity of Kw=4.1×10-10 m/s and a thermal conductivity of Γ=2.35 W/m/K. The other soil properties are: soil stiffness E=100 MPa, Poisson’s ratio ν=0.3, porosity n=0.25, solid grain thermal volumetric expansion coefficient αs=3.4×10-4 K-1. The same soil surface climatic conditions used in the first part were applied. The temperature evolution obtained in the road from the previously mentioned analyses (Figure 2 (a)) was imposed to reproduce the effect of the geothermal activation on the road behaviour. Furthermore, the soil surface is free of stress to study the soil swelling and settlement. The bottom limit of the soil column is hydraulically drained and allows heat flux (at constant liquid pressure and temperature). The lateral far field boundaries are thermally adiabatic, hydraulically impervious, and with oedometric conditions. The results were firstly compared with the case without geothermal activation to quantify the effects in terms of road heave and settlement (Figure 2 (b)). Swelling and settlement are due to thermal expansion and compression of the soil under positive temperature (T>0°C) and to frost heave and thaw settlement under negative temperature (T<0°C). The liquid pressure at the road surface is also depicted (Figure 2 (b)). These results and comparisions allowed understanding the performance of the technology in reducing road mechanical damage induced by freezing.

Quantification of design associated engineering properties of sesame (Sesamum indicum L.) seed varieties as a function of moisture content

AbstractThe investigation was intended to examine the influence of selected moisture levels (4.26, 12.66, 25.31, 37.89, 50.21% wet basis) on engineering properties namely, dimensional, gravimetric, frictional, aerodynamic as well as mechanical properties of five selected varieties of sesame seed namely GT‐3, GT‐4, GJT‐5, GT‐6, and TKG 22. The investigation finds out that fluctuations in moisture level significantly (p ≤ 0.05) influenced the engineering properties assessed. Increase in moisture content influenced a rise in length, width, thickness, geometric mean diameter, arithmetic mean diameter, sphericity, volume, volumetric expansion coefficient, elongation ratio, flakiness ratio, surface area, projected area, thousand seeds weight, compressibility index, Hausner ratio, angle of repose, coefficient of friction, terminal velocity and Reynolds number of selected sesame verities. Whereas, a reverse trend was observed in aspect ratio, true density, bulk density, tapped densities, drag coefficient, and hardness with moisture content variation. The frictional characteristic of the seed showed improved stability with less flow ability at higher moisture levels. These outcomes disclosed that variation of seed moisture content is authoritative during designing and construction of machinery and process equipment related to sesame. It may be also beneficial in computation of design for hoppers, silos, conveyors, drying, and heat transfer equipment as well as other sesame seed‐related process and handling equipment.

Właściwości reologiczne cieczy sprężysto-lepkoplastycznej

A model for the motion of a compressible elastic-viscous-plastic fluid in a round pipe is proposed. The main indicators of the flow, volume flow and speed are obtained. Numerous hydrodynamic processes are associated with the properties of liquids. It is known that the mechanical and physical properties of liquids can be described by various models. Various models have been proposed that partially describe the processes of hydromechanics. The proposed model makes it possible to qualitatively describe the deformation processes that occur in various systems. To describe a closed theory of motion of a continuous medium and, in particular, between stress and strain, it is necessary to have a mechanical model. From the literature analysis it is known that there are simple models, which include elastic, viscous and plastic. At the same time, it should be noted that the mechanical model partially shows the mechanical state of the elastic body in the form of Hooke's law. Practice shows that there are more complex liquids that do not obey this law. One of these fluids is an elastic-viscous-plastic fluid. In this work, a model is proposed that describes the elastic-viscous-plastic properties of liquids, which sequentially connects the elastic and viscous-plastic elements. For such a medium, the total resistance will be the sum of the stress corresponding to the elastic deformation and the stress caused by the viscous-plastic resistance. Based on the proposed model, an equation is obtained taking into account the coefficient of volumetric elastic expansion, and an equation is obtained for determining the velocity distribution over the pipe section and volume flow for a given liquid. Calculations have shown that with an increase in compressibility, the flow rate of the liquid partially increases, which in some practical cases produces a positive effect.

Generalized Theory for DISes in a Large Deformed Solid

Analysis of diffusion-induced stress in the electrode materials of metal-ion batteries, especially in silicon-anode lithium-ion battery with large deformation, involves an in-depth understanding of the interaction between atomic migration and matrix volume expansion. Under large migration velocity of solute atoms in a host matrix, such chemo-mechanical coupling can result in the damage or structural degradation of the matrix (electrode), leading to capacity fading. Incorporating the effects of concentration changing rate on strain energy in Helmholtz free energy and the finite deformation framework, a generalized theory has been established to solve stresses in an elasto-plastic electrode induced by lithiation. Numerical calculations of lithiation-induced stresses are performed in an amorphous nano-spherical silicon electrode by using the free-volume-based constitutive relation of amorphous materials and the generalized theory. We analyze the effects of the volumetric expansion coefficient associate with solute atoms and the volumetric expansion coefficient associate with the concentration changing rate of solute atoms on the stress evolution. The results reveal that the concentration changing rate of solute atoms likely accelerates surface cracking of electrode materials during lithiation.

Phase transition and thermal expansion of molecular perovskite energetic crystal (C6N2H14)(NH4)(ClO4)3 (DAP-4)

Research on the structural responses to thermal stimuli for crystalline energetic materials is crucial to their practical applications. DAP-4 is a metal-free molecular perovskite high-energetic material attracting increasing attentions on its application potential as heat-resistant explosive. In order to reveal its structural responses to thermal stimuli, herein we investigated the structural phase transitions and thermal expansion of DAP-4 by DSC, single-crystal X-ray diffraction, and variable-temperature capillary powder X-ray diffraction. The results show that DAP-4 undergoes two-step reversible phase transitions at 300.4/298.9 K and 548.4/547.7 K, respectively, which are caused by two-step order-disorder transition of the molecular components during a heating/cooling cycle. The axial and the volumetric expansion coefficients of DAP-4 are estimated based on the temperature-dependent cell parameters obtained by Pawley refinement in a large temperature range of 173–353 K, and they are close to those estimated for β-HMX. Notably, although a volume change of 0.77% occur in the near-room-temperature phase transition, all the crystalline phases of DAP-4 possess cubic structures with isotropic expansibility, rather than the commonly-observed anisotropic one in the most of known energetic crystals, which may be propitious to reduce the adverse effect of its volume change on the formulation design.

Optimal design of natural convection heat sinks by data-driven multifidelity topology design

In recent years, the demand for high-performance natural convection heat sinks has been increasing due to the miniaturization of electronic devices and their wide range of applications. It has become important to design a natural convection heat sink that can exhaust the maximum amount of heat with a compact size. In this study, we apply the framework of data-driven multifidelity topology design (MFTD) for the design problem of natural convection heat sinks. In this method, we initially prepare several promising and diverse solutions and iterate generating new solutions from them while preserving diversity and structural features and simultaneously arranging moderate perturbation. At each iteration, better solutions are selected as the seeds for generating the succeeding set of solutions, and they are arranged into new ones through a deep generative model. It is expected that repeating this operation finally reaches superior solutions without gradient information. We applied this framework to the 2D topology optimization problem. The shape of the heat sinks was optimized for several values of the coefficient of volumetric expansion (β), which is a number that determines the strength of convection. Different optimal structures were obtained by changing β, and they were reasonable. For example, the optimal solutions under strong convection had partial structures with rectifying effects.

A survey of thermal expansion coefficients for organic molecular crystals in the Cambridge Structural Database.

Typical ranges of thermal expansion coefficients are established for organic molecular crystals in the Cambridge Structural Database. The CSD Python API is used to extract 6201 crystal structures determined close to room temperature and at least one lower temperature down to 90 K. The data set is dominated by structure families with only two temperature points and is subject to various sources of error, including incorrect temperature reporting and missing flags for variable-pressure studies. For structure families comprising four or more temperature points in the range 90-300 K, a linear relationship between unit-cell volume and temperature is shown to be a reasonable approximation. For a selected subset of 210 structures showing an optimal linear fit, the volumetric expansion coefficient at 298 K has mean 173 p.p.m. K-1 and standard deviation 47 p.p.m. K-1. The full set of 6201 structures shows a similar distribution, which is fitted by a normal distribution with mean 161 p.p.m. K-1 and standard deviation 51 p.p.m. K-1, with excess population in the tails mainly comprising unreliable entries. The distribution of principal expansion coefficients, extracted under the assumption of a linear relationship between length and temperature, shows a positive skew and can be approximated by two half normal distributions centred on 33 p.p.m. K-1 with standard deviations 40 p.p.m. K-1 (lower side) and 56 p.p.m. K-1 (upper side). The distribution for the full structure set is comparable to that of the test subset, and the overall frequency of biaxial and uniaxial negative thermal expansion is estimated to be < 5% and ∼30%, respectively. A measure of the expansion anisotropy shows a positively skewed distribution, similar to the principal expansion coefficients themselves, and ranges based on suggested half normal distributions are shown to highlight literature cases of exceptional thermal expansion.

Interactional behavior of saccharides/derivatives with amoxicillin drug in aqueous medium: Insights from volumetric, calorimetric and spectroscopic studies

The physicochemical studies are significant in understanding the molecular interactions of saccharides and their derivatives with amoxicillin drug in aqueous solution. Therefore, the apparent molar volumes (V2,ϕ), and the limiting standard molar enthalpies of dilution (ΔdilH∞m) of saccharides and their derivatives in (0.001, 0.002, 0.003 and 0.004) mol·kg–1 aqueous solutions of amoxicillin were determined from the precise density, ρ and heat change, q measurements at (288.15, 298.15, 308.15 and 318.15) K under pressure, p = 0.1 MPa. The data were processed to obtain the corresponding transfer volumes (ΔtrV2∞) and enthalpies of dilution of transfer (ΔtΔdilH∞m) of solutes from water into aqueous solutions of amoxicillin. The volumetric expansion coefficients (∂V2∞/∂T)P, their second-order derivatives (∂2V2∞/∂T2)P and heat capacity change (∆dilC∞p,2,m) were also determined. Proton (1H) NMR spectra for mA = 0.02 mol·kg–1 saccharides/derivatives were also recorded in different molalities, mB = 0.001, 0.002, 0.003 and 0.004 mol·kg–1 of amoxicillin solution prepared in solvent {9:1 H2O + D2O}. The NMR results show that the Hc proton of amoxicillin has more activity (acidity) and it interacts more with the solute molecules (saccharide/derivative) than other protons of amoxicillin.

Effect of oxidation on the thermal expansion of a refractory multicomponent alloy

ABSTRACT We employ first-principles calculations to examine the role of oxidation on the thermal expansion behaviour of a refractory multicomponent alloy. Our results reveal that the linear expansion and the coefficient of volumetric expansion over a range of temperatures have higher values for the oxidised alloy than the pure material. The enhanced expansion for the oxidised alloy is attributed to significant changes in the lattice parameter of the alloy upon surface oxidation. During oxidation, the diffusion of oxygen atoms to the subsurface layer of the alloy after complete surface coverage produces a displacement of the constituent elements that form metal oxides. This depletion creates vacancy sites in the lattice for enabling enhanced expansivity in the oxidised structure relative to the pure refractory alloy.

Constrained dipole moment density functional theory for charge distributions in force fields for the study of molecular fluids

A new procedure, based on electronic structure calculations that only requires a dipole moment value for a given molecule as input and, from which the charges for all the atoms in it are uniquely determined, is developed and applied to the study of molecular fluids with classical dynamics. The dipole moment value considered for the isolated molecule is the one that reproduces the dielectric constant of its corresponding fluid. Following previous work, the Lennard-Jones parameters are determined to reproduce the liquid density and the surface tension at the liquid-vapor interface. The force field thus obtained leads to a reasonable description of several properties such as heats of vaporization, self-diffusion coefficients, shear viscosities, isothermal compressibilities, and volumetric expansion coefficients of pure substances.

Physical characterization of sunflower seeds dehydrated by using electromagnetic induction and low-pressure system

Drying is a widely used food preservation process in which water removal minimizes much of the moisture that causes deterioration reactions that impact the bioproduct quality. The objects of studying are high oleic sunflower seeds which are recognized as a worldwide source of edible oil; consequently, they have significant importance on health and food security. This work presents part of the results of a systematic study to compare the affectations on the several physical parameters of sunflower seeds and kernels with the Thermo-Solar Dehydration method (TSD) compared to Dehydration with Electromagnetic Induction at Low Pressures (DEMI-LP), finding that the in the last one the time to reach the 8% of the total moisture content was 2.5 times shorter, interesting physical effects and an increment of 5% in the volumetric expansion coefficient, reflected in a reduction of the cut resistance (Dehull) of 0.5KgF significant advantages for the food drying industry.

Thermal Transitions of Cocoa Butter: A Novel Characterization Method by Temperature Modulation.

For the first time, the novel experimental technique Temperature Modulated Optical Refractometry (TMOR) was employed for cocoa butter thermal transitions characterization. The average refractive index (NMEAN), the volume (v) change, and the volumetric expansion coefficient () as well as the dynamic quantities and (real and imaginary volumetric expansion coefficient, respectively) were monitored during cooling and heating and compared to the heat flow curves obtained via the standard technique dynamic scanning calorimetry (DSC). The investigation of these quantities showed that TMOR analysis can yield not only thermal transitions temperatures that are comparable to DSC results, but also some new thermal events that are not detected by DSC. This outcome suggests that TMOR might provide some additional insights on cocoa butter melting and crystallization by means of frequency-dependent measurements due to temperature modulation. This new information that can be accessed during temperature ramps might provide a deeper insight into thermal behavior of fat-based foods, evidencing TMOR value as a tool for thermal transitions investigation.

Conformational flexibility Tuned positive thermal expansion in Li-based 3D metal−organic framework

Hydrothermal treatment of flexible linker 5,5′-(propane-1,3-diylbis(oxy)) diisophthalic acid (pdta) and LiOH generated a novel FL-MOF (flexible ligand based metal-organic framework) of conformational flexibility, showing gradual structural changes from 1D helical banded structure to 3D accordion-pleats-like network. Ultralight metal Li-based FL-MOF possesses hingelike movement of −O−(CH2)3−O− flexible moieties on pdta linker, which resulted in large positive thermal expansion (PTE) behavior with volumetric expansion coefficient of 163.7860 MK−1.

Estimation of the Gruneisen parameter and an explicit measure of anharmonicity of dodecaborides

In previous works on the ratio (θД – the characteristic temperature of Debye, was calculated according to the Lindemann formula; V – molar volume of hypothetical lattice atoms; γ is the Gruneisen parameter) for the group of dodecaborides (TbB12, DyB12, HoB12, ErB12, TuB12, LaB12, UB12) the average value of γ = 1.3 was determined. However, due to the ambiguity of the coefficient of proportionality in the Lindemann formula by definition θD, the authors selected an independent high-temperature X-ray method for determining the dependence θr (T). Taking into account the immutability of the structure and type of interatomic connection in the temperature interval of the search (293–973 K), the authors evaluated the value and temperature dependence of γ (T) of each dodecaboride separately. The results of the search showed that the value of γ for each given dodecaboride is different, but practically independent from temperature. For some dodecaborides, the parameter γ is about 2–3 units, and for others it is overestimated. The values of γ made it possible to estimate the magnitude of the implicit γβ and the explicit parts of the universal measure of anharmonicity of dodecaborides , where β – real coefficient of volumetric expansion of the crystalline lattice. Because (n – dimensionless coefficient of proportionality), then the temperature change n(T) is also determined.

Determination of the Temperature Dependence of the Isobaric Volumetric Expansion Coefficient for Certain Molecular Crystals of Nitro Compounds

This paper presents the form of the equations of state of molecular crystals of nitro compounds constructed on the basis of dividing Helmholtz free energy into an intramolecular and an intermolecular components. This division enabled us to determine the form of the Gruneisen equation for molecular crystals, the volume dependence of the Gruneisen coefficient, and the temperature dependence on the volumetric expansion coefficient. Comparative analysis of the calculated and experimental values of volumes of elementary cells of triaminotrinitrobenzene crystals depending on the temperature has shown their fair agreement.

Force Field Parametrization from the Hirshfeld Molecular Electronic Density.

The Hirshfeld charges are linearly increased to reproduce the experimental dielectric constant of 10 polar solvents having values between 13 (pyridine) and 182 ( N-methylformamide). The OPLS/AA force field is used to obtain the new parameters. The surface tension and liquid density are also target properties to determine the new nonbonding parameters. The charge scaling factor is between 1.2 and 1.3. In addition, properties that were not used in the parametrization procedure, such as the heat of vaporization, self-diffusion coefficient, shear viscosity, isothermal compressibility, and volumetric expansion coefficient are obtained. Binary mixtures of amide/water and amide/amide are also studied. The original parameters of OPLS/AA, CGenFF, and GAFF force fields are evaluated. The TIP4P/ε force field is used to simulate water. The results from this work with the new parameters, for both pure components and binary mixtures, are in better agreement with experimental data than those obtained with the original values for most of the calculated properties. The maximum density of N-methylformamide in aqueous solutions is correctly predicted only with the new parameters. The high value of the dielectric constant of acetamide, formamide, and N-methylformamide is discussed in terms of the chain formation from the hydrogen bond interactions.

Thermoelastic properties of microcracked polycrystals. Part II: The case of jointed polycrystalline TATB

The thermoelastic responses of a cracked TATB polycrystal is modeled using Fourier-based numerical computations and linear homogenization estimates. The numerical method is based on a Fourier scheme previously investigated (Gasnier et al., 2018) and the homogenization schemes include a new self-consistent estimate recently developed for cracked polycrystals. The effect of various populations of intergranular and transgranular microcracks are compared, with special attention to thermal behavior in the percolating regime. A model of micro-cracks is proposed for the TATB material in its initial state and the variations of the volumetric expansion coefficient of the TATB polycrystal under thermal cycles, during cooling and heating, are interpreted.