Numerical and experimental data set for benchmarking hygroscopic buffering models

This paper presents experimental data measured in a bed of gypsum boards in the transient moisture transfer (TMT) facility at the University of Saskatchewan. The relative humidity and temperature were measured at two depths in a gypsum bed and the moisture accumulation was measured for the entire bed. Experiments were conducted for both coated (acrylic and latex paint) and uncoated gypsum. These experimental data are compared to simulated data from eight different numerical models. The agreement between the experimental and numerical data is good and often within the experimental uncertainty bounds. A sensitivity analysis was performed to show the influence of material properties such as sorption, vapour permeability and the transfer coefficients on the simulated results. One model examines hysteresis of the sorption isotherm.     

Higher Order Finite Volume Central Schemes for Multi-dimensional Hyperbolic Problems

Different ways of implementing dimension-by-dimension CWENO reconstruction are discussed and the most efficient method is applied to develop a fourth order accurate finite volume central scheme for multi-dimensional hyperbolic problems. Fourth order accuracy and shock capturing nature of the scheme are demonstrated in various nonlinear multi-dimensional problems. In order to show the overall performance of the present central scheme numerical errors and non-oscillatory behavior are compared with existing multi-dimensional CWENO based central schemes for various multi-dimensional problems. Moreover, the benefits of the present fourth order central scheme over third order implementation are shown by comparing the numerical dissipation and computational cost between the two.     

Influence of heat treatment parameters on structure and mechanical properties of an HSLA‐100 steel

An HSLA‐100 steel received from the US Naval Research Laboratory has been characterised. The effects of heat treatment parameters such as austenitisation time and temperature, tempering time and temperature on mechanical properties have been studied. The microstructures resulting from different heat treatment conditions have been correlated with mechanical properties through SEM and TEM studies. Quantitative relationships have been developed between mechanical properties and the operational variables within a narrow range of variation of the variables by statistical design of experiments. A quantitative relationship has also been developed for the same for a wider experimental region through curve fitting technique. The best combination of strength and low‐temperature toughness was obtained in the region of 700 °C tempering temperature and 0.3 ‐ 0.4 h tempering time.     

Effect of glycine addition on the in-vitro corrosion behavior of AZ31 magnesium alloy in Hank's solution

This study reports on the effect of the addition of Glycine to Hank's solution on the in-vitro corrosion behavior of AZ31 magnesium (Mg) alloy at 37 ℃ and a pH of 7.4 studied by using potentiodynamic polarization (PDP),hydrogen collecting techniques and electrochemical impedance spectroscopy (EIS) in combination with surface characterization techniques such as optical microscopy (OM),scanning electron microscopy(SEM),energy dispersive spectroscopy (EDS),X-ray diffraction (XRD) and X-ray photoelectron spectroscopy analysis (XPS).The results reveal that adsorption of glycine initially subdues the dissolution ofAZ31 Mg alloy while in long run it enhances the dissolution of the alloy due to the commencement of the chelation effect ofglycine with Ca2+ released from hydroxyapatite.The chelation ofglycine with Ca2+induces the formation of cracks in the surface film which further promotes the dissolution ofAZ31 Mg alloy thereby forming a porous corrosion products layer on the surface of the alloy.As a result,both the continuous dissolution of AZ31 magnesium alloy and the hydrogen evolution rate (HER) are enhanced with increasing the immersion time in Hank's solution.     

Impact of Exogenous Silicate Amendments on Nitrogen Metabolism in Wheat Seedlings Subjected to Arsenate Stress

We intended to investigate the response of arsenate on nitrogen metabolism in wheat seedlings and aimed to assess the efficacy of silicon amendments in modulating the metabolic disturbances caused by arsenate stress. The nitrogen metabolism of wheat cultivated in different levels of arsenate with or without silicate in a medium supplemented with modified Hoagland’s solution for 21 days was studied. Experimental design was completely randomized with different arsenate concentrations (0, 25, 50 and 100 μM) with or without 5 mM silicate. Arsenate treatment decreased growth along with decline in nitrate (NO3−) uptake and accumulation. Activities of nitrate reductase (NR), nitrite reductase (NiR), glutamine synthetase (GS) as well as glutamate synthase (GOGAT) were lowered in the test seedlings. Decline in nitrite (NO2−) and amino acid contents were also evident along with an enhancement in the accumulation of toxic ammonia. Silicate supplementation under arsenate stress however, improved growth, repaired the arsenate-induced effects leading to an enhancement in nitrate (NO3−) uptake and consequently improved nitrite (NO2−) and amino acid contents as well. The total and soluble nitrogen contents were enhanced along with enhancements in activities of enzymes associated with nitrate metabolism while ammonia accumulation was lowered. Results therefore, imply the involvement of exogenous silicon amendments in relieving the metabolic alterations in nitrogen metabolism caused by arsenate stress that enabled wheat seedlings to adapt under arsenate excess and eventually promoted plant growth.     

Energy savings in a building using regenerative evaporative cooling

This paper explores the potential of reducing the annual energy consumption of a central air-conditioned building through advanced evaporative cooling systems. The building considered is a typical three floor library building of a University. The regenerative evaporative cooling technology is coupled with the liquid cooled water chiller system to accomplish the energy conservation objective. Comparisons of the regenerative evaporative cooling are made with simple evaporative cooling to bring out the importance such a system. The well-known building simulation software, TRNSYS is used to carry out the heat load calculations and the dynamic simulations of the building. Annual energy consumptions of different components of the air-conditioning system are estimated for the existing water chiller system as well as for both coupled evaporative cooling systems (simple and regenerative). The annual energy consumptions, the indoor temperature, the relative humidity and the thermal comfort index ‘PMV’ are compared for all the three different air-conditioning systems. The coupling of direct and regenerative evaporative cooling technologies with water chiller system has shown, respectively, 12.09% and 15.69% savings in annual energy consumption of the building, while maintaining PMV between ?1 and +1 for most of the hours in the year.