Investigation of Energy Modelling Methods of Multiple Fidelities: A Case Study

Building energy modelling has become an integral part of building design due to energy consumption concerns in sustainable buildings. As such, energy modelling methods have evolved to the point of including higher-order physics, complex interconnected components and sub-systems. Despite advances in computer capacity, the cost of generating and running complex energy simulations makes it impractical to rely exclusively on such higher fidelity energy modelling for exploring a large set of design alternatives. This challenge of exploring a large set of alternatives efficiently might be overcome by using surrogate models to generalize across the large design space from an evaluation of a sparse subset of design alternatives by higher fidelity energy modelling or by using a set of multi-fidelity models in combination to efficiently evaluate the design space. Given there exists a variety of building energy modelling methods for energy estimation, multi-fidelity modelling could be a promising approach for broad exploration of design spaces to identify sustainable building designs. Hence, this study investigates energy estimates from three energy modelling methods (modified bin, degree day, EnergyPlus) over a range of design variables and climatic regions. The goal is to better understand how their outputs compare to each other and whether they might be suitable for a multi-fidelity modelling approach. The results show that modified bin and degree day methods yield energy use estimates of similar magnitude to each other but are typically higher than results from EnergyPlus. The differences in the results were traced, as expected, to the heating and cooling end-uses, and specifically to the heat gain and heat loss through opaque (i.e., walls, floors, roofs) and window surfaces. The observed trends show the potential for these methods to be used for multi-fidelity modelling, thereby allowing building designers to broadly consider and compare more design alternatives earlier in the design process

Polyaniline/palladium nanohybrids for moisture and hydrogen detection.

Palladium nanoparticles display fascinating electronic, optical and catalytic properties, thus they can be used for various applications such as sensor fabrication. Conducting polymers such as polyaniline have also been widely used in sensor technology due to its cost effectiveness, versatility, and ease of synthesis. In this research, attention was given to unify the exceptional properties of these two materials and construct palladium nanoparticle coated polyaniline films to detect hydrogen and moisture. Electrochemical polymerization of aniline was carried out on gold sputtered epoxy resin boards. Polyaniline film was generated across a gap of 0.2 mm created by a scratch made on the gold coating prior to electrochemical polymerization. A palladium nanoparticle dispersion was prepared using sonochemical reduction method and coated on to polyaniline film using drop-drying technique. Polyaniline only films were also fabricated for comparative analysis. Sensitivity of films towards humidity and hydrogen was evaluated using impedance spectroscopy in the presence of the respective species. According to the results, polyaniline films exhibited an impedance drop in the presence of humidity and the response was significantly improved once palladium nanoparticles were incorporated. Interestingly, polyaniline only films did not respond to hydrogen. Nevertheless, palladium nanoparticle coated polyaniline films exhibited remarkable response towards hydrogen

MRAP : marketing military innovation

Military procurement has a generally poor popular perception, as costing too much, taking too long, and generally underperforming expectations. We might assume that wartime, emergency procurement of military materiel would be easier, but it too can be surprisingly difficult. Conflicts over military priorities, industrial unpreparedness, and politicians’ access to information can pose serious challenges. Fortunately, there are many pathways to military innovation, but industry – the agent which actually produces new materiel – is one that is systematically under-appreciated in the literature. I ask how, when unexpected battlefield problems arise, industry, the military, and government can work together to bring innovative, wartime solutions. To answer this question, I examine the case of a disruptive military threat during the American counterinsurgent campaign in Iraq – that of the improvised explosive device, or IED, and of the response with a particular type of military vehicle – the Mine-Resistant, Ambush-Protected vehicle, or MRAP, largely from 2003 through 2007. I have used this case to propose new theory on the under-appreciated importance of marketing in military procurement.Public Polic

Symmetric projected entangled-pair states analysis of a phase transition in coupled spin-<math><mfrac><mn>1</mn><mn>2</mn></mfrac></math> ladders

International audienceInfinite projected entangled-pair states (iPEPS) have been introduced to accurately describe many-body wave functions on two-dimensional lattices. In this context, two aspects are crucial: the systematic improvement of the Ansatz by the optimization of its building blocks, i.e., tensors characterized by bond dimension D, and the extrapolation scheme to reach the “thermodynamic” limit D→∞. Recent advances in variational optimization and scaling based on correlation lengths demonstrated the ability of iPEPS to capture phases with spontaneously broken continuous symmetry such as the antiferromagnetic (Néel) one with high fidelity, in addition to valence-bond solids which are already well described by finite-D iPEPS. In contrast, systems in the vicinity of continuous quantum phase transitions still present a challenge for iPEPS, especially when non-Abelian symmetries are involved. Here, we consider the iPEPS Ansatz to describe the continuous transition between the (gapless) antiferromagnet and the (gapped) paramagnet that exists in the S=1/2 Heisenberg model on coupled two-leg ladders. In particular, we show how accurate iPEPS results can be obtained down to a narrow interval around criticality and analyze the scaling of the order parameter in the Néel phase in a spatially anisotropic situation

Data from: Selection past impacts the strength of an aquatic trophic cascade

1. In complex food webs, interactions among species in different trophic levels can generate cascading indirect effects that couple top predators with primary producers, thereby affecting ecosystem functioning. Natural selection imposed by top predators on intermediate predators may play a role in shaping the strength of these trophic cascades, but this conjecture remains largely untested. 2. To determine the effects of natural selection on the strength of trophic cascades we conducted a two-part experiment in a four-level aquatic trophic system involving a top predator (fish), an intermediate predator (damselflies), herbivores (zooplankton), and primary producers (algae). We first quantified how predation by fish generated selection on damselfly activity levels after controlling for phenotypic plasticity. We then measured the indirect effects of this selection on primary production (phytoplankton biomass). In both experiments we varied the density of predators, allowing us to elucidate both trait-mediated and density-mediated indirect effects. 3. We found that as fish density increased, damselfly survivorship declined, which generated natural selection favoring less active damselflies. These results are robust after taking into account latent effects of plasticity in response to fish predator cues. The surviving damselflies likely foraged less, freeing herbivores from predation, which in turn reduced primary production. This selection driven trait-mediated indirect effect was only apparent at low damselfly densities, because the consumptive effect of damselflies at high densities overwhelmed the effects of past selection. 4. These results demonstrate that the past action of natural selection can affect the strength of a trophic cascade. Natural selection can therefore act as a mechanism coupling ecological dynamics across trophic levels, which ultimately influences ecosystem functioning

Synthesis and characterization of electroactive films deposited from aniline dimers

The electrochemical oxidation of the aniline dimers 2-aminodiphenylamine (2-adpa) and 4-aminodiphenylamine (4-adpa) has been performed in strongly acidic medium on platinum, graphite, and indium tin oxide electrodes. The resulting films have been characterized by a number of electrochemical, microscopic, and spectroscopic techniques in order to gain some insight on their respective chemical structures. Both poly(2-adpa) and poly(4-adpa) are electroactive species which differ significantly one from another. It was found that aged poly(4-adpa)displayed electrochemical, morphologic and spectroscopic characteristics similar to those shown by polyaniline. On the contrary, poly(2-adpa) is really a mixture of three oligomerization products. The two main oligomers contain both open-ring and cycled phenazine centers, although their chemical structures seem to differ in the cap-end of the chain growth. The third oligomer is a minor product which seems a highly symmetric macrocycle involving several 2-adpa molecules.This work has been cofinanced by the European Commission (ERDF funds) and the Spanish Ministerio de Educación y Cultura (MAT2004-01479). University of Alicante assisted in meeting the publication costs of this article