Analysis of the behavior of transverse walls of socket base connections

This paper presents a theoretical and experimental analysis of socket base connections of precast concrete structures with regard to the behavior of transverse walls. The experimental program included seven specimens, for which the type of interface in contact with cast-in-place concrete, the load eccentricities and the embedded lengths were all varied. A design model was proposed to calculate the reinforcements of the transverse walls. Based on the obtained results, some conclusions can be drawn: (a) The top of the transverse wall on the compression side of the smooth connections and the top of the two transverse walls of the rough connections are submitted to a bending-tension and this tension prevails on the bending; (b) The design model proposed for the calculation of the reinforcement of the transverse wall on the compression side provides the best prediction of the experimental results for all specimens when compared to the current design models; (c) For rough interfaces, the top of the transverse wall on the tension side is more requested than the top of transverse wall on the compression side; (d) The results of the proposed design model for the reinforcement of the transverse wall on the tension side of rough connections were in close agreement with the experimental results.     

A systematic methodology for kinetic modeling of chemical reactions applied to n‐hexane hydroisomerization

Kinetic modeling provides chemical engineers with a unique opportunity to better understand reaction kinetics in general and the underlying chemistry in particular. How to systematically approach a modeling assignment in chemical reaction kinetics is typically less clear, especially for novices in the field. The proposed modeling methodology pursues an adequate compromise between statistical significance and physical meaning of the kinetic model and the corresponding parameters and typically results in models of an appropriate complexity. It comprises the following activities: (1) data analysis, aiming at qualitative information on the reaction mechanism and corresponding rate equations, (2) model regression to quantify this information via optimal parameter values, and (3) validation of the statistical significance and physical meaning of the parameter estimates. This methodology is successfully applied to n‐hexane hydroisomerization on a bifunctional catalyst. © 2014 American Institute of Chemical Engineers AIChE J, 61: 880–892, 2015     

Phase Stability and Optoelectronic Properties of the Bixbyite Phase in the Gallium–Indium–Tin–Oxide System

X‐ray diffraction techniques were used to determine the phase boundaries of the In₂O₃ solid solution phase in the Ga₂O₃–In₂O₃–SnO₂ ternary system. The effects of Ga and Sn content on the unit cell dimensions of the bixbyite phase were calculated by a linear regression fit, the results of which indicate the two substitutive cations have opposite and independent effects on the lattice parameter. These results suggest that the cations do not strongly interact with each other in the crystal. Measurements of optoelectronic properties were also taken on single‐phase bulk specimens within the solid solution to establish their dependence on composition. As anticipated, Sn doping yields corresponding increases in conductivity, reduction in the absolute value of Seebeck coefficient, and increase in optical band gap. In contrast, these properties are not significantly affected by varying Ga content, confirming that Ga behaves as an isovalent dopant at the low doping levels involved.     

Power Spectral Density Analysis of Pressure Fluctuation in Pneumatic Conveying of Powders

In order to reveal the unsteady features of gas–solid flow, the pressure fluctuations were measured at different locations along the length of the pipeline while conveying powders through the pipeline. Power spectral density (PSD) functions were obtained for the analysis of the pressure fluctuation. Two types of powders (fly ash and alumina) were used in this analysis. The PSD analysis was conducted by taking into account different aspects such as flow conditions (dilute or dense), location of transmitter (top and bottom transmitters), location of transmitter along the length of the pipeline (three different locations), material property (fly ash or alumina), etc. Analysis of signals from top and bottom transmitters shows that it is not possible to identify the flow mode at upper and lower portions of pipeline. The magnitude of power is found to be higher for alumina as compared to fly ash. PSD parametric analysis reveals that frequency bandwidth and average power decreases exponentially with increase in solid loading ratio.     

A portable data system for reindeer herd management

A portable computer system is described which supports timely data management for reindeer herding. An initial version has been in use for two years, supporting research on reindeer diseases. Versions are being developed which will expand the system to support commercial herd management. The hardware system is integrated from commercially available equipment. The software is currently composed of a set of ten programs, with others under development for enhancements and modifications. At field roundups, the computer allows new animals to be added to the data base plus rapid access to information on existing individual animals. Historical information can be displayed, including detailed historical records of reproductive activity, medical treatments, serological exam results, and observations of anomalies (e.g. infections, injuries, etc.). In the field, or in the lab, the data base may be accessed for information on specific animals and for summaries of herd data.     

A Mixture Toxicity Study Employing Binary Combinations Of Dinitrobenzene And Trinitrobenzene Using The Bioluminescent Marine Bacterium Vibrio Harveyi As The Test Organism

A combination mixture study was conducted with two organic compounds, dinitrobenzene and trinitrobenzene, using the marine bioluminescent bacterium Vibrio harveyi . This assay employs the photogenic properties of this organism for determination of toxicity in a direct procedure. Evaluation of toxicity was performed using an additive index methodology, mixture toxicity index and graphic representations. Graphic representations employed were isobole plot and isobologram, both isopleths. The additive index procedure employed both chemicals at their estimated median effective concentration (EC 50 ) for determination of a toxicity value. Isopleths employed combinations of both chemicals, using an equitoxic concentration, at 20% intervals of their EC 50 . An additive index value for this mixture was statistically antagonistic. Mixture toxicity index suggests that these chemical in various combinations are antagonistic. Combinations for both isopleths were similar and exhibited additivity for three mixture values and statistical synergism for one mixture. Statistical analysis of combinations using the z test found some mixtures to be statistically different. This analysis, in part, supports findings for isopleths. These results suggest that different mixtures of the two chemicals may have different interaction outcomes.     

Liminality,Seasonality and Landscape

To the student of landscape, as well as to the landscape planner, designer and manager, it is important to distinguish between differing modalities in the conceptualization of landscape and seasonality. The logic of the absolute geometric space of the map and central point perspective prospect, and the chronometric time of the calendar, is qualitatively different from the liminality of place and seasonal holidays. Here it is the content that defines the seasons, not the regularities of a quantitative system of measurement. This distinction is critical when it comes to working with seasonal landscapes, because they can be defined in terms of either modality.     

Copper(I)-Dioxygen Adducts and Copper Enzyme Mechanisms

Primary copper(I)-dioxygen (O₂) adducts, cupric-superoxide complexes, have been proposed intermediates in copper-containing dioxygen-activating monooxygenase and oxidase enzymes. Here, mechanisms of C−H activation by reactive copper-(di)oxygen intermediates are discussed, with an emphasis on cupric-superoxide species. Over the past 25 years, many synthetically derived cupric-superoxide model complexes have been reported. Due to the thermal instability of these intermediates, early studies focused on increasing their stability and obtaining physical characterization. More recently, in an effort to gain insight into the possible substrate oxidation step in some copper monooxygenases, several cupric-superoxide complexes have been used as surrogates to probe substrate scope and reaction mechanisms. These cupric superoxides are capable of oxidizing substrates containing weak O−H and C−H bonds. Mechanistic studies for some enzymes and model systems have supported an initial hydrogen-atom abstraction via the cupric-superoxide complex as the first step of substrate oxidation.