Activation energies as the validity criterion of a model for complex reactions that can be in oscillatory states

Modeling of any complex reaction system is a difficult task. If the system under examination can be in various oscillatory dynamic states, the apparent activation energies corresponding to different pathways may be of crucial importance for this purpose. In that case the activation energies can be determined by means of the main characteristics of an oscillatory process such as pre-oscillatory period, duration of the oscillatory period, the period from the beginning of the process to the end of the last oscillation, number of oscillations and others. All is illustrated on the Bray-Liebhafsky oscillatory reaction

Cerium oxide based nanometric powders: synthesis and characterization

Nanometric powders of solid solutions of cerium oxide were obtained by a modified glycine nitrate procedure. Solid solutions of the host compound CeO2 with one or more dopants in the lattice were synthesized. Rare earth cations (Re=Yb, Gd and Sm) were added to ceria in total concentration of x= 0.2 that was kept constant. The criterion in doping was to keep the value of lattice parameter of ceria unchanged. The lattice parameters were calculated by using the model that takes into account the existence of oxygen vacancies in the structure

Crystal structure analysis of Nd-doped ceria solid solutions

This paper deals with Nd-doped ceria solid solutions: Ce1-xNdxO2-d with "x" ranging from 0 to 0.25. Six different powders were synthesized by applying the method based on selfpropagating room temperature reaction (SPRT) between metallic nitrates and sodium hydroxide. The method is known to assure very precise stoichiometry of the final product in comparison with a tailored composition. Rietveld refinement was employed to get structural information on the synthesized powder. An increase of Nd ion concentration increases the unit cell parameters and average bond distances. We have shown that all obtained powders were solid solutions with a fluorite-type crystal structure and all powder particles were of nanometric size (about 3 nm)

Meta models for real-time design assessment within an integrated information and numerical modelling framework

In situations where rapid decisions are required or a large number of design alternatives is to be explored, numerical predictions of construction pro-cesses have to be performed in near real-time. For the design assessment of com-plex engineering problems such as mechanised tunnelling, simple numerical and analytical models are not able to reproduce all complex 3D interactions. To over-come this problem, in this paper a novel concept for on-demand design assess-ment for mechanized tunnelling using simulation-based meta models is proposed. This concept includes: i) the generation of enhanced simulation-based meta mod-els; ii) real-time meta model-based design assessment in the design tool, and; iii) the implementation within a unified numerical and information modelling plat-form called SATBIM. The capabilities of this concept are demonstrated through an example for the evaluation of tunnel alignment design and the assessment of the impact of tunnelling on existing infrastructure. Moreover, meta models are used for fast forward calculation in sensitivity analyses for the evaluation of the importance of model parameters. The concept proved its efficiency by assessing the design alternatives in real-time with the prediction error of less than 3% com-pared to complex numerical simulation in presented example

Automated Planning of Concrete Joint Layouts with 4D-BIM

Concrete pouring represents a major critical path activity that is often affected by design limitations, structural considerations and on-site operational constraints. As such, meticulous planning is required to ensure that both the aesthetic and structural integrity of joints between cast in-situ components is achieved. Failure to adequately plan concrete pouring could lead to structural defects, construction rework or structural instability, all having major financial implications. Given the inherent complexity of large-scale construction projects, the ‘manual planning’ of concrete pouring is a challenging task and prone to human errors. Against this backdrop, this study developed 4D Building Information Management (BIM) approach to facilitate automated concrete joint positioning solution (as a proof of concept) for design professionals and contractors. The study first developed structural model in Revit, then extracted spatial information regarding all construction joints and linked them to dynamic Microsoft (MS) Excel and Matlab spreadsheets using integration facilitated by Dynamo software. Midspan points of each beam as well as floor perimeter information were gathered via codes developed in MS Excel macros. Based on the Excel outputs, Matlab programming was used to determine best concreating starting points and directions, and daily allowed concrete volume, considering limitations due to cold joints. These information were then pushed back to Revit via Dynamo in order to develop daily concrete scheduling. The developed automated programme framework offers a cost-effective and accurate methodology to address the limitations and inefficiencies of traditional methods of designing construction joints and planning pours. This framework extends the body of knowledge by introducing innovative solutions to integrate structural design considerations, constructional procedures and operational aspects for mitigating human error, and providing a novel, yet technically sound, basis for further application of BIM in structural engineering

Body mass index is independently associated with xanthine oxidase activity in overweight/obese population

Purpose: The pathophysiological mechanism of the relationship between xanthine oxidase (XO) activity and obesity has not been completely elucidated. Since inflammation and oxidative stress are regarded as key determinants of enlarged adipose tissue, we aimed to investigate the association between oxidative stress (as measured with XO activity), inflammation [as measured with high-sensitivity C-reactive protein (hsCRP)] and obesity [as measured with body mass index (BMI)]. In addition, we wanted to examine whether hsCRP itself plays an independent role in XO activity increase or it is only mediated through obesity. Methods: A total of 118 overweight/obese volunteers (mean age 54.76 ± 15.13 years) were included in the current cross-sectional study. Anthropometric, biochemical parameters, and blood pressure were obtained. Results: Significant differences between age, BMI, waist circumference, concentrations of uric acid and hsCRP, as well as xanthine dehydrogenase (XDH) activities were evident among XO tertile groups. Multiple linear regression analysis revealed that BMI (beta = 0.241, p = 0.012) and XDH (beta = − 0.489, p < 0.001) are the independent predictors of XO activity (R2-adjusted = 0.333), whereas hsCRP lost its independent role in XO activity prediction. Conclusion: Obesity (as determined with increased BMI) is an independent predictor of high XO activity in overweight/obese population. Level of Evidence: Level V: cross-sectional descriptive study