Simplified mathematical modelling for a solar humidification compression desalination system

The performance of a solar humidification‐dehumidification desalination where dehumidification is carried out by compression is studied. The mathematical models are developed to assess the effect of operating condition on desalination system. Two models are developed for solar heater and humidifier tower and after solving the models, the obtained results are compared with the experimental data for model verification. The results indicate a good conformity between the model and experimental data. There exist a 1.9–13.3% error between experimental data and modelling. The lowest error is assigned to water temperature in the humidifier and the highest to air temperature in the solar heater.     

Effects of biophilic interventions in office on stress reaction and cognitive function: A randomized crossover study in virtual reality

Biophilia hypothesis suggests humans have an innate connection to nature which may affect our health and productivity. Yet we currently live in a world that is rapidly urbanizing with people spending most of their time indoors. We designed a randomized crossover study to let 30 participants experience three versions of biophilic design in simulated open and enclosed office spaces in virtual reality (VR). Throughout the VR session, we measured blood pressure, heart rate, heart rate variability, and skin conductance level and administered cognitive tests to measure their reaction time and creativity. Compared to the base case, participants in three spaces with biophilic elements had consistently lower level of physiological stress indicators and higher creativity scores. In addition, we captured the variation in the intensity of virtual exposure to biophilic elements by using eye‐tracking technology. These results suggest that biophilic interventions could help reduce stress and improve creativity. Moreover, those effects are related to both the types of biophilic elements and may be different based on the workspace type (open vs enclosed). This research demonstrates that VR‐simulated office spaces are useful in differentiating responses to two configurations and among biophilic elements.     

The influence of heat treatment on the microstructure,flux pinning and magnetic properties of bulk BSCCO samples prepared by sol-gel route

We study the combined influence of calcination and sintering temperature on the microstructure, superconducting and pinning properties of Bi_1.6Pb_0.4Sr₂Ca₂Cu₃O_10+θ (Bi-2223) prepared by the sol-gel route. Using several characterization techniques, including X-rays diffractometry and electrical transport measurements, we find that the powders calcined at 820 °C often result in a crystal higher critical current density (J_c) compared those calcined at 830 °C. The powder calcined at 820 °C and sintered at 850 °C (Bi-2223 ₈₂₀⁸⁵⁰) showed the best grain morphology and the largest magnetic hysteresis loop and a J_c equal to 12.94 $\times$ 10⁵ A/cm², comparable to the best results found in the literature for Bi-2223. The enhancement in J_c for Bi-2223 ₈₂₀⁸⁵⁰ seems to be due to improved grain structure rather than creation of effective pinning centers, because the scaling behavior of flux pinning force densities indicates that the main pinning mechanism for all samples is normal point pinning.     

A high-resolution time-resolved study of incoherent interface motion during the massive transformation in TiAl alloy

Frame-by-frame analyses of in-situ high-resolution transmission electron microscope (HRTEM) heating experiments performed on a high-index incoherent massive transformation interface in TiAl alloy at 575 °C show that the interface displays dynamic fluctuations in its trace that can be described in terms of a wavelike function with an amplitude of 0.21 nm and a fundamental wavelength of 1.15 nm. The interface moves forward with a constant average velocity of 0.023 nm/s, due to spreading of critical-size advancing fluctuations along the interface at different locations, which causes it to remain relatively planar as it advances. This interface behavior is remarkably similar to that observed during previous in-situ optical microscopy studies on massive transformation interfaces in Cu-Ga alloy and is distinctly different from the behavior of highly faceted interphase boundaries. This article is based on a presentation made in the “Hume-Rothery Symposium on Structure and Diffusional Growth Mechanisms of Irrational Interphase Boundaries,” which occurred during the TMS Winter meeting, March 15–17, 2004, in Charlotte, NC, under the auspices of the TMS Alloy Phases Committee and the co-sponsorship of the TMS-ASM Phase Transformations Committee.     

Material flow determination for radial flexible profile ring rolling

Regarding the increasing demand on annular components with complex geometries, a flexible process has been developed at the IBF to profile sleeve shaped rings. Unlike processes using grooved tools, here diverse contours can be realized on the inner surface using one “universal” tool. By extending the tool kinematics and developing an adequate forming strategy the general feasibility of the process has been shown on a bench scaled model ring rolling rig using a wax based model material. Parameters such as ring/tool geometry and roller feed strategy were detected as having an effect on material flow resistance in the rolling and transverse directions. Expressing them by geometric ratios, the material flow distribution could be determined in numerous experiments and quantified by a newly-defined extension coefficient with a certainty of 95%. This achievement enables us to predict the material flow in axial and tangential directions to manufacture complex geometries reproducibly.     

Experimental and parametric study on drying of green peas in spouted bed

Drying of Green Peas (Pisum sativum) was studied experimentally in a lab‐scale spouted bed. Experiments were carried out at different operating conditions, and the effect of inlet air temperature and its flow rate, bed height (initial mass of wet particles) and average diameter of particles were examined on performance of dryer and rate of drying. The obtained experimental results were fitted by an exponential form equation to model the drying kinetic behaviour of green peas in a spouted bed. The fitting parameters are presented in the form of mathematical correlations as a function of operating parameters. As expected, it was found that by increasing inlet air temperature and air‐flow rate, the rate of drying increases, but by increasing the bed height and diameter of particles, the rate of drying decreases. The results can help the design engineers to choose the optimum drying conditions for industrial applications.     

A high-resolution time-resolved study of incoherent interface motion during the massive transformation in TiAl alloy

Frame-by-frame analyses of in-situ high-resolution transmission electron microscope (HRTEM) heating experiments performed on a high-index incoherent massive transformation interface in TiAl alloy at 575°C show that the interface displays dynamic fluctuations in its trace that can be described in terms of a wavelike function with an amplitude of 0.21 nm and a fundamental wavelength of 1.15 nm. The interface moves forward with a constant average velocity of 0.023 nm/s, due to spreading of criticalsize advancing fluctuations along the interface at different locations, which causes it to remain relatively planar as it advances. This interface behavior is remarkably similar to that observed during previous in-situ optical microscopy studies on massive transformation interfaces in Cu−Ga alloy and is distinctly different from the behavior of highly faceted interphase boundaries. This article is based on a presentation made in the “Hume-Rothery Symposium on Structure and Diffusional Growth Mechanisms of Irrational Interphase Boundaries,” which occurred during the TMS Winter meeting, March 15–17, 2004, in Charlotte, NC, under the auspices of the TMS Alloy Phases Committee and the co-sponsorship of the TMS-ASM Phase Transformations Committee.     

Investigation of the Soret effect in copper nanoparticle colloids by self-phase modulation and Z-scan

A theoretical investigation is reported on the photo-thermal response of copper nanoparticle colloids in the presence of thermal and mass diffusion processes. The absorbed laser beam energy is converted into heat and generates a temperature gradient, which causes nanoparticle concentration variation in the fluid. Transverse spatial redistribution of the nanoparticles induces changes in absorption and refraction of the medium. Experimentally, the photo-thermal response was determined by measuring absorption and refraction changes of the nanoparticle colloids using the far-field diffraction patterns and Z-scan technique. This allowed evaluation of the Soret coefficient of the nanoparticle colloids and excellent agreement is found in measuring this coefficient using both the far-field diffraction pattern and Z-scan technique.     

Substituent Effect On Structure,Stability, and Electronic Properties of the Novel Bicyclic Silylenes at DFT

Silicon - The density functional theory (DFT) calculations are carried out to assay the effects of nitrogen atoms on the stability and reactivity of singlet (s) and triplet (t) forms of novel...