Computing diffuse fraction of global horizontal solar radiation: A model comparison

For simulation-based prediction of buildings’ energy use or expected gains from building-integrated solar energy systems, information on both direct and diffuse component of solar radiation is necessary. Available measured data are, however, typically restricted to global horizontal irradiance. There have been thus many efforts in the past to develop algorithms for the derivation of the diffuse fraction of solar irradiance. In this context, the present paper compares eight models for estimating diffuse fraction of irradiance based on a database of measured irradiance from Vienna, Austria. These models generally involve mathematical formulations with multiple coefficients whose values are typically valid for a specific location. Subsequent to a first comparison of these eight models, three better performing models were selected for a more detailed analysis. Thereby, the coefficients of the models were modified to account for Vienna data. The results suggest that some models can provide relatively reliable estimations of the diffuse fractions of the global irradiance. The calibration procedure could only slightly improve the models’ performance.     

Nonlinear static and dynamic behavior of three-lobe non-circular gas lubricated micro bearings at high operating temperatures and/or high rotational speeds

Microsystem Technologies - When micro-bearings are operated at high temperatures or high rotation speeds such that gas rarefaction occurs, the conventional Reynolds model is not accurate enough to...     

An objective method to evaluate exemplar‐based inpainted images quality using Jaccard index

Multimedia Tools and Applications - Objective evaluation of images is one of the most essential and practical aspects of image inpainting. The existing objective evaluation methods of image...     

Synthesis,characterization, and application of a triazene‐based polysulfone as a dye adsorbent

Novel triazene‐based polysulfone, poly 4‐(4‐aminophenylsulfonyl)diazobenzene, was synthesized from 4‐[(4‐aminobenzene)sulfonyl]aniline (Dapsone) in the presence of sodium nitrite/silica sulfuric acid system, under solvent‐free conditions, and also in aqueous media to compare their polymerization process and the products. The structures of the obtained polymers under the two conditions were characterized for the first time in this investigation by several analytical and spectroscopic methods such as FT‐IR, ¹H‐NMR, UV–vis, thermogravimetric and differential thermal analyses, gel permeation chromatography, mass spectrometry, and CHN micro‐elemental analysis. The results showed that both polymerization processes had made the same product; nevertheless, the solvent‐free conditions afforded silica‐coated poly 4‐(4‐aminophenylsulfonyl)diazobenzene. In another study, the ability of the silica‐coated polymer, to remove some usual applied water‐soluble dyes by spectrophotometric detection, was measured in which cationic structure dyes such as Rhodamine B and Cationic blue 41 were preferably adsorbed. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Harnessing buildings’ operational diversity in a computational framework for high-resolution urban energy modeling

To achieve computational efficiency, efforts toward developing urban-scale energy modeling applications frequently rely on various domain simplifications. For instance, heat transfer phenomena are captured using reduced order models. As a consequence, specific aspects pertaining to the temporal dynamics of energy load patterns and their dependency on transient phenomena (e.g., weather conditions, inhabitants’ presence and actions) cannot be realistically represented. To address this circumstance, we have conceived, implemented, and documented a two-step urban energy modeling approach that combines cluster analysis and sampling techniques, full dynamic numeric simulation capability, and stochastic methods. The paper describes the suggested urban energy modeling approach and the embedded cluster analysis supported sampling methodology. More particularly we focus on the aspects of this approach that explicitly involve the representation of inhabitants in urban-scale energy modeling. In this regard, the potential to recover lost dynamic diversity (e.g., in computation of temporal load patterns) due to the deployed reductive sampling is explored. Parametric runs based on stochastic variations of underlying building use profiles facilitate the generation of highly realistic load patterns despite the small number of buildings selected to represent the simulation domain. We illustrate the utility of the proposed urban energy modeling approach to address queries concerning the energy efficiency potential of behaviorally effective instruments. The feasibility of the envisioned scenarios concerning inhabitants and their behavior (high-resolution temporal load prediction, assessment of behavioral variation) is presented in detail via specific instances of district-level energy modeling for the city of Vienna, Austria.