Decreasing Computational Time of Urban Cellular Automata Through Model Portability

This paper investigates how portability of a model between different computer operating systems can lead to increased efficiency in code execution. The portability problem is not a trivial one, as many geographic models are designed to be run inside a set environment (Unix, Solaris, Linux, and Windows), and are further limited by hardware constraints. The SLEUTH urban growth model [K.C Clarke, S. Hoppen, and L. Gaydos. “A self-modifying cellular automaton model of historical urbanization in the San Francisco Bay area”, Environment and Planning B, 24:247–261, 1997.] was implemented under three different operating systems (Solaris, Linux, and Windows). Results suggest that the model's performance is optimized by porting it from its original environment (Unix/Solaris) to Linux or Windows where faster processors are available. While the results show optimization of model performance, there are some suggestions of computational bottlenecks that may eventually limit the increased performance of the model. Regardless, the research demonstrates that the portability of a model can lead to not only to a decrease in computation time, but may increase the viability in practical applications and attract a wider user base.     

Processing of thin film ceramic membranes for oxygen separation

Processing of dense and thin ceramic membrane layers for high temperature selective oxygen separation is addressed in this study. Mixed oxygen-ionic and electronic conducting perovskite oxide system based on La_0.2Sr_0.8Fe_0.8Ta_0.2O_3−δ composition is employed for processing of structural and functional layers. Special focus is aimed at obtaining thin layer and final microstructure with particle size in the sub-micron range. Thin layer deposition is performed by dip coating technique using stable colloidal suspension of perovskite particles dispersed within ethanol media. Two polymer based surfactants were screened for their effect on particle agglomeration and rheological response. By using optimum quantity of 2.5 wt.% addition of selected surfactant it is possible to obtain dense 15-60 μm thick functional layers. The thermal cycle applied resulted in final particle sizes within sub-micron range. By employing suspension with pore former it was possible to significantly increase the surface area of the functional layer.     

Classification of Intact Cereal Flours by Front-Face Synchronous Fluorescence Spectroscopy

Synchronous fluorescence spectroscopy, a technique that measures both the absorption and the emission properties of a sample in a single measurement, was used for the analysis and classification of intact cereal flours (wheat, corn, rye, buckwheat, rice, and barley). Total synchronous fluorescence spectra recorded in constant wavelength mode show clear differences in the emission spectra of different flours due to variances in intrinsic fluorophore concentrations and their microenvironments. Principal component analysis, cluster analysis, and partial least squares discriminant analysis are used to assess the ability of synchronous fluorescence measurements to differentiate and classify intact samples of different flour types. The flour specimens were obtained directly from a market in Belgrade and had different expiration dates to provide a more representative set of samples. The results of the current analysis suggest that chemometric methods applied on synchronous fluorescence data can discriminate and classify flour types and that the best results are achieved using a combination of synchronous fluorescence measurements at synchronous intervals of 7 and 20 nm. The quality of results, the high speed of measurements, and the avoidance of extensive sample preparation make synchronous fluorescence spectroscopy a promising technique for cereal research.     

Evaluating the mixing of organic aerosol components using high-resolution aerosol mass spectrometry

According to the pseudo-ideal mixing assumption employed in practically all chemical transport models, organic aerosol components from different sources interact with each other in a single solution, independent of their composition. This critical assumption greatly affects modeled organic aerosol concentrations, but there is little direct experimental evidence to support it. A main experimental challenge is that organic aerosol components from different sources often look similar when analyzed with an aerosol mass spectrometer. We developed a new experimental method to overcome this challenge, using isotopically labeled compounds ((13)C or D) and a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS). We generated mixtures of secondary organic aerosol (SOA) from isotopically labeled toluene and from unlabeled α-pinene and used the HR-ToF-AMS data to separate these different SOA types. We evaluated their interaction by comparing the aerosol mass yields of toluene and α-pinene when the SOA was formed in these mixtures to their yields when the SOA was formed in isolation. At equilibrium, our results are consistent with pseudo-ideal mixing of anthropogenic and biogenic SOA components from these chemically dissimilar precursors.     

The potential for small scale hydropower development in the US

In an earlier paper (Kosnik, 2008), the potential for small scale hydropower to contribute to US renewable energy supplies, as well as reduce current carbon emissions, was investigated. It was discovered that thousands of viable sites capable of producing significant amounts of hydroelectric power were available throughout the United States. The primary objective of this paper is to determine the cost-effectiveness of developing these small scale hydropower sites. Just because a site has the necessary topographical features to allow small scale hydropower development, does not mean that it should be pursued from a cost-benefit perspective, even if it is a renewable energy resource with minimal effects on the environment. This analysis finds that while the average cost of developing small scale hydropower is relatively high, there still remain hundreds of sites on the low end of the cost scale that are cost-effective to develop right now.     

Chemical compatibility of proton conducting LaNbO4 electrolyte with potential oxide cathodes

The chemical and physical compatibility of the proton conducting electrolyte material LaNbO₄ with the potential partner materials LaMO₃ (MMn, Fe, Co) and La₂NiO₄ is investigated via the reaction of fine-grained powders and solid-state diffusion couples. Results show generally good chemical compatibility for LaNbO₄ with perovskite type compositions, particularly the LaFeO₃ and LaMnO₃ systems. In contrast, Ruddlesden–Popper type phases are predicted to be poor candidates for use with LaNbO₄. Investigation of the La₂O₃–NiO–Nb₂O₅ and La₂O₃–CoO–Nb₂O₅ phase diagrams finds two new perovskite-related materials of stoichiometry LaNb_1/3M_2/3O₃ (MNi, Co), and indicates coexistence of LaNbO₄ with the binary oxides NiO and CoO. Additionally, reduction of a LaNbO₄–NiO composite confirms coexistence of LaNbO₄ with Ni, and so it is concluded that doped-LaMO₃|LaNbO₄|Ni-LaNbO₄ type electrochemical cells may be manufactured via a direct co-firing route without the formation of secondary phases at inter-phase boundaries.     

Optimal Link Weights for IP-Based Networks Supporting Hose-Model VPNs

From traffic engineering point of view, hose-model VPNs are much easier to use for customers than pipe-model VPNs. In this paper we explore the optimal weight setting to support hose-model VPN traffic in an IP-based hop-by-hop routing network. We try to answer the following questions: (1) What is the maximum amount of hose-model VPN traffic with bandwidth guarantees that can be admitted to an IP-based hop-by-hop routing network (as opposed to an MPLS-based network), and (2) what is the optimal link weight setting that can achieve that? We first present a mixed-integer programming formulation to compute the optimal link weights that can maximize the ingress and egress VPN traffic admissible to a hop-by-hop routing network. We also present a heuristic algorithm for solving the link weight searching problem for large networks. We show simulation results to demonstrate the effectiveness of the search algorithm.     

Tuning the Thermal Relaxation of a Photochromic Dye in Functionalized Mesoporous Silica

In this study, it is shown that the kinetics of the back‐switching reaction of a photochromic spirooxazine dye encapsulated in mesoporous silica materials can be significantly influenced both by the space available to the dye molecules and by the functionalization of the silica wall. Steric hindrance of the ring‐closing process due to high dye content or small pore size leads to a slow fading speed of the irradiated dye species. Further, the density of surface silanol‐groups present at the silica walls has an effect on the switching behavior of the dye because of their ability to stabilize the zwitterionic merocyanine isomers, thereby slowing the fading process from the open to the closed form. This stabilization effect is further enhanced in the presence of acidic functional groups, while, in contrast, basic functional groups reduce the stabilization of the open‐from dye isomers, and thus a faster decay of the irradiated species is observed. Control over the fading speed of photochromic dyes is interesting for applications requiring a particularly fast or slow fading speed.