Trial application of ASHRAE 1051-RP: calibration method for building energy simulation

ASHRAE research project 1051-RP generated a method to improve the process of calibrating whole building energy simulation models based on monthly utility data. The approach, using manual generation of simulation model variations, was applied to a 12,000 m² high-performance, dual energy, cold climate building. This led to 27 models that met the ASHRAE Guideline 14 monthly goodness-of-fit criteria for electricity, but had fit values for gas that were about 5–7 times the normalized mean bias error (NMBE) acceptance threshold. Five models met the criteria for natural gas and had acceptable coefficient of variation of the root-mean-square error for electricity, but NMBE was about 100% too high. Use of finer interval monitored data yielded a model with electrical NMBE about 60% above the acceptance threshold, and gas use about 200% above. Hourly analysis of the thermal energy demand on the plant showed wide discrepancies with the estimates on an hourly and half daily basis.     

Improvements to the structural condition index (SCI) for pavement structural evaluation at network level

Structural evaluation provides valuable information about the expected behaviour and response of pavements and can be used at the network level of pavement management to prioritise projects. The falling weight deflectometer (FWD) can be used to identify the beginning and end of management sections and group pavement sections with similar structural capacities. The structural condition index (SCI) was developed as a screening tool for the pavement network-level evaluation, and the FWD data are used to determine the SCI. For the successful implementation of the SCI concept at the network level, one of the critical issues is the accuracy of the index. This article evaluates the accuracy of the SCI and also discusses a concept and procedure how to improve the SCI and its algorithm for low-volume flexible pavements. A case study (Texas) illustrates that the original SCI algorithm underestimates the existing structural condition, resulting in overestimated treatments in the pavement maintenance and rehabilitation.     

Effects of worker size on the dynamics of fire ant tunnel construction

Social insects work together to complete tasks. However, different individuals within a colony may vary in task proficiency. We investigated if fire ant (Solenopsis invicta) worker body size influenced the ability to construct tunnels—a key component of subterranean nests. We monitored excavation by worker groups in a substrate of small wetted glass particles in quasi-two-dimensional arenas. Morphological and network features of the tunnel system were measured. Total tunnel area did not differ significantly between groups of large and small workers, although the tunnel area of control sized workers was significantly larger than that of large workers. Moreover, large workers created wider but shorter tunnels, with slower growth rate of tunnel number. However, edge–vertex scaling and degree distribution of the tunnel network were similar across all treatments. In all cases, the amount of excavated material was correlated with the number of active workers. Our study reveals that morphological features of excavated tunnels show modest variation when constructed by workers of varying sizes, but topological features associated with the tunnel network are conserved. These results suggest that important behavioural aspects of tunnel construction—and thus nest building—are similar among morphologically distinct members of fire ant societies.     

Comparison of calculations for interplanar distances in a crystal lattice

The derivations for the general formulae of lattice interplanar distances are reviewed along with the methods using elementary geometry, intermediate Cartesian axes, and reciprocal lattice vectors. To highlight the characteristics of these three methods and the connections between them, examples for the simple cases such as orthorhombic, hexagonal, and rhombohedral systems are included. Calculations from reciprocal space are established from those from direct space with heavily involved mathematics for which details are seldom included in crystallography monographs. The only geometric method found in the literature for the interplanar distances in a crystal lattice is derived for a few specific simple cases with cos²α?+?cos²β?+?cos²γ?=?1, where α, β, and γ are the angles between the normal to the plane and the axes of a orthogonal system. However, the geometric method introduced in this work is a newly developed method and this method is complementary to other methods including the advanced contemporary reciprocal method. The connections between Cartesian and crystal coordinate systems, for angular relationships and the volume of unit cell are revealed. The interplanar spacing in non-primitive lattice and crystals are also discussed.     

Experimental and theoretical assessment of the inhibiting action of <Emphasis Type="Italic">Aspilia africana</Emphasis> extract on corrosion aluminium alloy AA3003 in hydrochloric acid

The adsorption of Aspilia africana extract and subsequent corrosion inhibition of aluminium alloy AA3003 in hydrochloric acid solutions have been investigated using gravimetric and electrochemical techniques. Inhibition efficiency increased with extract concentration and temperature rise. Polarization studies revealed that the extract essentially inhibited the cathodic reaction. An adsorption mechanism involving physisorption and chemisorption of extract constituents at low and high temperatures, respectively, has been proposed from the trend of adsorption-free energies. Quantum chemical computations and molecular dynamics simulations described the individual contributions of some extract constituents to the observed inhibiting effect.