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A research facility with solar thermal collector system and a water-saturated, sand-based seasonal thermal energy storage (SSTES) is used to provide space heating and domestic hot water heating to homes in cold climates. A 3D finite difference model of the heat transfer in and around the SSTES is presented and validated with measured data. The SSTES has lost moisture over time, making its thermal properties difficult to estimate. Additionally, the experimental data shows the SSTES losing heat at twice the expected rate, potentially due to incorrect thermal parameters from the manufacturer and the SSTES insulation being damaged or degraded. The final numerical model was validated over a 163-day period where energy was being injected into and extracted from the SSTES. It was found that the seasonal performance of the SSTES could be predicted by a conduction-only heat transfer model, and this model is suitable to be included in BPS tools. [ABSTRACT FROM AUTHOR]

This study presents a 1D finite difference model that examines the influence of cloth fabrics on skin temperature during and after exercise, considering the complex nature of the human body and its susceptibility to infections and viruses. The aim is to design comfortable, high-quality fabrics that minimize potential issues caused by body temperature fluctuations. The model incorporates various physical, physiological, and thermal parameters of cloth to develop protective clothing suitable for exercise. Numerical results were compared to previous studies that analyzed skin temperature without clothing to validate the model’s accuracy. The findings indicate a minimal difference in skin temperature when wearing cotton and polyester cloth, with polyester fabric demonstrating superior characteristics such as stretchability, durability, and sweat resistance. The thermal information obtained from this model can be utilized to design appropriate clothing for diverse weather conditions, ultimately enhancing the performance and comfort of athletes, military personnel, and individuals engaged in physically demanding work. Additionally, the model can aid in developing thermal stress protocols for infection treatment and provide guidelines for physical activity to promote healthy living. This research contributes to the field of materials research by offering valuable insights into the design and development of protective clothing for exercise. By understanding the impact of cloth fabrics on skin temperature, advancements can be made in creating clothing that optimizes human comfort and performance.

Investigation of heavy metal transport in water bodies such as dam reservoirs due to the environmental hazards and the transformation complexities of heavy metals from dissolved phase to particulate phase and vice versa is of particular importance. The transport process of the dissolved heavy metals such as lead (Pb) in storage dam reservoirs is significantly influenced by the water flow, and ambient parameters such as temperature, total dissolved solids (TDS), dissolved oxygen (DO), and suspended solids (SS). Due to the lack of a suitable model to simulate the heavy metal transport in dam reservoirs, in this study, the hydrodynamics and water quality model, CE-QUAL-W2, was enhanced by developing 2D laterally averaged model for simulating the dissolved phase of Pb contaminant and applied to the Shahid Rajaei Dam reservoir, Sari, Iran. The developed model can describe the advection–dispersion and transformation processes and simulate the temporal and spatial distribution of dissolved phase of Pb concentrations. A new approach was introduced to calculate different reaction coefficients used in the transformation term of the advection–diffusion equation. Comparison of the simulation results of temperature, TDS, DO, SS, and dissolved phase of Pb with the measured values from the Shahid Rajaei Dam reservoir shows a mean percentage error (MPE) of 6.8, 4.7, 11.7, 19.7, and 7.27 respectively. The results of the present study showed that the temperature was the most effective parameter on the transformation of Pb in the Shahid Rajaei Dam reservoir due to large changes of temperature in depth as about 15 °C along with small changes in other ambient parameters in several months of the year. This phenomenon can be expected in many reservoirs that are stratified in a period of the year. However, the effect of other ambient parameters such as TDS, DO, and SS should not be neglected. [ABSTRACT FROM AUTHOR]

Transverse solute mixing across a vegetation generated horizontal shear layer was quantified using laser induced fluorometry techniques for artificial and real vegetation. A two-dimensional finite difference model (FDM) was developed to describe transverse concentration profiles for flows containing transverse variations in velocity and transverse dispersion, from a steady solute input. The FDM was employed inversely, to optimize the parameters describing the transverse distribution of the transverse dispersion coefficient for vegetation generated shear layers. When laboratory data are available, continuous function descriptions produce slightly improved FDM modelled solute concentration profiles compared with simplified step discontinuity velocity and dispersion inputs. When laboratory data are not available, estimates of step or continuous transverse distributions from other work enable concentration profiles to be predicted with a similar goodness of fit. This paper presents a validated, simple, robust finite difference model to describe the mixing of solutes in a channel containing marginal vegetation. [ABSTRACT FROM AUTHOR]

• Training data sets are generated by a validated finite difference method model. • Mapping method predictions agree well with data sets from independent sources. • The new method predicts performance of wheels with different physical geometries. • The new approach method requires fewer training data points than current models. Energy recovery ventilators are often employed in buildings to decrease the energy consumed by their HVAC systems, and to improve overall indoor air quality. Several studies in the open literature have developed physical or empirical models to simulate the performance of energy recovery wheels. However, these models are often computationally intensive, time-consuming, or require numerous experimental data points to train and execute the performance predictions. These models also tend to lack flexibility for varying all of the available wheel design parameters. Hence, developing a mapping method with better computational efficiency and flexibility is the goal of this research. A finite difference numerical model for simulating the performance of an energy wheel has been developed and validated using experimental test results from independent laboratories. This model was then employed to provide an extensive data set for the development of an energy wheel performance mapping method. After validating this new mapping approach, the method predictions were compared against independent data sets from two different laboratories, and additional sources available in the literature, to identify its universality. The mapping method delivers good agreement between the predictions and validation data, and requires only a small number of data points to train, which is one of its novel contributions. Another unique contribution of the proposed mapping method is that once the model is trained it can predict the performance characteristics for other wheels with different physical design geometries and operating conditions, provided only that the desiccant material is the same. [ABSTRACT FROM AUTHOR]

Accurate prediction of thermal regime (i.e. the variation of soil temperature, θ, and heat flux, ϕ) to investigate the migration of thermal energy in soil mass, poses challenge to the geoenvironmental engineers while dealing with various thermo-active structures. In this context, several numerical approaches have been attempted to solve the heat transfer equation (HTE) for conduction to predict the thermal regime. However, most of them need accurate boundary condition defined and involve complicated numerical approach which is inconvenient for the practising engineers. Hence, an attempt has been made in the present study to develop a simplified, but numerically efficient, approach based on the finite difference method (FDM) to analyse one dimensional heat transfer in dry sands when the end boundary is not defined. Furthermore, a time-dependent initial boundary condition has been applied to this model to simulate similar experimental condition and results have been compared vis-à-vis those obtained from the experiment and COMSOL Multiphysics® to validate the proposed approach. [ABSTRACT FROM AUTHOR]

The temperature distribution is one of the most vital parameters which should be fully considered in high geothermal tunnel design. For the purpose of studying the impact of temperature disturbance caused by construction on temperature distribution of surrounding rock and lining structure in a high geothermal tunnel, a new finite difference model for temperature prediction was proposed. Based on the abundant field test results, forecast analysis for the research of a high geothermal tunnel in this paper is made. The results indicate that the temperature of the surrounding rock near the tunnel sidewall decreases obviously in the first 14 days while that of the surrounding rock far away is stable after tunnel excavation, and the rock temperature showed three ways of change: undulate type (5 m). There is a linear relationship between the initial rock temperature and the released heat of the surrounding rock. The radius of the heat-adjusting layer and the initial rock temperature presents a quadratic function relation. The lining concrete actually cures under the variable high-temperature environment and the real curing temperature decreases with time and becomes stable seven days later. The results would contribute to providing support for high geothermal tunnel research and design.

Abstract This study is focused on the development of a finite difference model to simulate Lamb wave propagation through Single Lap Joints (SLJs). The main advantage of this model is the mathematical ability to easily reproduce the presence of a damage (debonding) as a discontinuity in velocity values. This makes our model suitable for continuous and embedded Structural Health Monitoring (SHM) of a complex structure. Numerical simulations and experimental campaigns are presented in order to validate the proposed model. [ABSTRACT FROM AUTHOR]

This study develops a coupled nonlinear hydrodynamic model of a mooring system consisting of multiple cables for analyses of floating offshore wind turbines (FOWTs). The model is based on a finite difference model of submerged cables which considers cable-seabed interaction, current effect, cable bending and torsional stiffness. The implementation of the model proposes a parallelization scheme for solving the cable responses to improve the computational efficiency. The developed program is then coupled with a spar type FOWT and verified using an experimentally validated open source mooring simulation program. Furthermore, the model is used to study the impact of nonlinear dynamics of the mooring system on FOWT responses in the presence of current. Both static responses of a spar FOWT under current load and dynamic responses of the spar FOWT under wind, wave and current loads are investigated. Responses are compared where varied mooring models are used including the linear model, quasi-static model and nonlinear mooring models without and with current effect on cables considered. The results show that the current effect on cables can have a considerable impact on the restoring effect of the mooring system and hence the spar and cable responses. The current effect on mooring cables needs to be properly considered in the FOWT analysis. [ABSTRACT FROM AUTHOR]

The temperature distribution is one of the most vital parameters which should be fully considered in high geothermal tunnel design. For the purpose of studying the impact of temperature disturbance caused by construction on temperature distribution of surrounding rock and lining structure in a high geothermal tunnel, a new finite difference model for temperature prediction was proposed. Based on the abundant field test results, forecast analysis for the research of a high geothermal tunnel in this paper is made. The results indicate that the temperature of the surrounding rock near the tunnel sidewall decreases obviously in the first 14 days while that of the surrounding rock far away is stable after tunnel excavation, and the rock temperature showed three ways of change: undulate type (<2 m), decline type (2–5 m) and stable type (>5 m). There is a linear relationship between the initial rock temperature and the released heat of the surrounding rock. The radius of the heat-adjusting layer and the initial rock temperature presents a quadratic function relation. The lining concrete actually cures under the variable high-temperature environment and the real curing temperature decreases with time and becomes stable seven days later. The results would contribute to providing support for high geothermal tunnel research and design. [ABSTRACT FROM AUTHOR]

Copyright of China Petroleum Machinery is the property of China Petroleum Machinery Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper reports on the investigation of the loading rate of nickel onto an iminodiacetic acid ion exchange resin (TP207XL) under the finite solution volume condition in the presence of ferrous in a batch loading system. A hybrid correlation model (McKevitt, 2012) was applied for nickel-ferrous displacement loading data. The experimental fit parameters of the hybrid correlation were used to successfully predict the results of the batch loading experiments by applying the finite difference model. The finite difference model was applied to predict the loading behavior of nickel in the presence of ferrous in the batch system using the modified Helfferich number and the linear isotherm equation. As confirmed, the ion exchange reaction examined in this study was predominantly controlled under some combination of intraparticle diffusion/ion exchange reaction. Regarding the hybrid correlation fit parameters (D app = 9.95 × 10 − 12 m 2 /s, α = 0.65), these parameters correlated well with the loading behavior of nickel onto resin. [ABSTRACT FROM AUTHOR]

A snow layer on a heated pavement strongly affects the energy balance at the pavement surface. Freshly fallen snow has a fairly low thermal conductivity and acts as a good insulator. The thermal properties can vary greatly during the melting process. This study looks into the change of the thermal conductivity during the melting process of dry uncompressed and compressed snow on heated pavements. The energy balance of the heated pavement system is described and the effective thermal conductivity of the melting snow layer during the melting process of snow on a heated pavement system is calculated based on the volume fractions and thermal conductivity of ice, water and air. The results show that the thermal conductivity of an uncompressed and compressed melting snow layer on a heated pavement can be best described as a combination of a parallel and series system. Ice and air are modelled as a series system and water and ice/air are modelled in parallel. [ABSTRACT FROM AUTHOR]

The work in hand presents results of an experimental and numerical research on the post-heating residual strength of a basalt textile refractory composite submitted to tensile loading. The tensile tests were performed after a preheating process at temperatures ranging from 25 to 1000 °C. The mechanical performance and cracking mechanisms were discussed and compared to that obtained at room temperature. Image analysis by means of digital image correlation method was used to obtain the evolution of crack width which was subsequently correlated with the stress response for all target temperatures. Scanning electron microscopy was used to investigate the damage processes in the fiber–matrix interfaces after exposure to high temperatures. A finite difference model was used to simulate the tension stiffening behavior of TRC (Textile Reinforced Concrete) systems predicting their crack spacing and stress vs. strain responses. The obtained results indicated that due to the coating decomposition the reliability of basalt TRC can only be guaranteed from room temperature to 150 °C. [ABSTRACT FROM AUTHOR]

This paper treats the wave control of suspended ropes by a control law based on the finite difference model. The control is acted on one finite difference interval inside of the upper fixed end. The control input is the distributed force equivalent to the difference between the boundary node equations and the interior node one. This control compensation of the boundary condition with use of the wave propagating solution of the interior node equation makes the boundary state as if it were the interior nodes. The wave propagating solution of the finite difference model of suspended rope is obtained as the transfer function between adjacent node displacements in the frequency domain that gives the convolution integral kernel function in the time domain. The simulation of the suspended rope systems with or without load mass at the free lower end boundary and with load mass at the fixed lower end boundary have been conducted. The frequency response analysis and numerical time simulation have confirmed the presented wave control effectiveness. The lower end boundary condition of a suspended rope has been also discussed.

Copyright of Journal of Harbin Institute of Technology. Social Sciences Edition / Haerbin Gongye Daxue Xuebao. Shehui Kexue Ban is the property of Harbin Institute of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this paper we apply the finite-difference method to solve a parabolic equation of a general problem of short wave diffraction in a conducting medium. It is based on the implicit Runge-Kutta method of the second order combined with the iterative procedure. We also present new numerical simulations for X-rays focusing using the mentioned approach. We consider CRLs with a parabolic profile with a radius of curvature up to 0.2 mm. The main goal of this work is to elaborate an X-ray calculator for a PC which would present new possibilities compared to conventional ones. The correspondent code is written in FORTRAN to obtain the focal distance and diffraction spot profiles. Simulations for two cases were performed, the first one with 33 Al lenses for X-ray energy 15 keV, the results showed that we needed to consider more than 50000 points in each direction which forced us to consider a one-dimensional simulation only. For the second case we performed a simulation for several lenses, up to 15 Al lenses to perform the 2-d simulation. We have good agreement with the experimental data for the focal distance, and for the intensity at the focal plane while, for the spot size, we have smaller FWHM for the Gaussian beam at the detector than in the experimental data. We believe that the FWHM we have is smaller as our lenses are ideal without any defects.

Numerical and empirical models addressing the drying shrinkage cracking behavior of joint-free steel-fiber-reinforced concrete (SFRC) slabs are presented. Effect of water--cement ratio, admixtures, and free shrinkage are considered. Mechanical restrictions including base friction, fiber dosage, and interfacial bond properties restrain the growth of microcracks into main cracks and also reduce crack opening. A model based on a finite-difference equilibrium solution of a one-dimensional (1D) slab on frictional ground simulates the formation and subsequent opening of cracks in the slab. Results are compared with an empirical predictive tool for crack opening. A sensitivity study shows that correlation of predicted crack opening reduced by increasing fiber volume, base friction, and interfacial bond strength. Case studies are conducted on three slabs in service at different occasions and both models are used to predict the crack opening. While these models are developed based on different methodologies, they are related to a great extent by addressing the same mechanical characteristics. A simple method to estimate the slab curl is proposed and a parametric study has been conducted. [ABSTRACT FROM AUTHOR]

Objective: This study evaluated the localization precision of 256-channel dense array electroencephalographic source imaging (dESI) in comparison to conventional noninvasive tools. In addition, the study was designed to analyze the relationship between the 256-channel dESI source patterns and surgical outcome. Methods: Forty-three patients with temporal lobe epilepsy (TLE) who underwent one-stage resective surgeries were recruited in this study. We compared dESI with other noninvasive evaluation methods by comparing results with resections that eliminate or significantly reduced seizures according to sublobule and lobule criteria. Sensitivity and specificity of multiple evaluation methods were calculated. Kaplan-Meier analysis was performed to evaluate the relationship between source patterns and surgical outcome. Results: dESI showed the best sensitivity (sub-lobule, 91.4%; lobule, 97.1%) and specificity (75%) for both sub-lobule and lobule criteria. The Kaplan-Meier survival analysis showed that cases with ''single source'' had better prognosis than with ''multiple sources'' (p < 0.05); cases of ''sources within resection'' showed better surgical prognosis than cases of ''sources outside resection'' (p < 0.05). Conclusion: In this study, 256-channel dESI provided a higher clinical yield than the other most broadly used noninvasive presurgical workup tools. dESI results with ''single source'' correlated strongly to good prognosis, while cases with ''multiple sources'' may cautiously be considered as candidates for one-stage resective surgeries. The resection of the irritative zone identified by interictal epileptiform discharges (IEDs) was related to good surgical prognosis in TLE. Significance: In the presurgical workup of TLE, the clinical yield of 256-channel dESI is high. Patterns of dESI results are related to surgical prognosis, and they can be instructive for presurgical planning. The resection of the irritative zone can be related to good surgical prognosis in TLE. [ABSTRACT FROM AUTHOR]

A 3D barotropic finite difference model was adapted to reproduce the dynamics of the Ría de Vigo estuary, in the north-west corner of Spain. The model has been applied with astronomical tide and observed wind forcing data. The results are compared to data obtained by an AANDERAA DCM 12 acoustic Doppler current meter at one point of the Ría.

The surface quality of steels containing solutes that have a strong affinity for oxygen can be markedly compromised during processing at elevated temperatures. Here, we examine a class of steels that are being developed for low density applications and hence, have relatively large concentrations of aluminium and manganese. These two elements compete for what little oxygen is available in the predominantly hydrogen-nitrogen mixture used to protect the steel during heat treatment. It is found that although the general sequence of oxidation does not seem to vary as the aluminium concentration is increased, the stoichiometry of the oxides changes. Manganese rich oxide is always the first to form for all the dew points examined, but is rapidly overtaken by aluminium oxide when the dew point is kept below 230°C. In the latter case, the eventual formation of an alumina film also halts the internal oxidation of aluminium. The results obtained using a variety of high resolution microscopy and analytical techniques have been analysed by calculating phase diagrams and by creating a finite difference model to reveal aspects of the internal oxidation problem. [ABSTRACT FROM AUTHOR]