Text complexity of open educational resources in Portuguese: mixing written and spoken registers in a multi-task approach

Language Resources and Evaluation - This paper presents a study on text complexity of Open Educational Resources (OER) in Brazilian Portuguese. In a data analysis of the Brazilian Ministry of...     

Quantification of denitrification potential in carbonaceous trickling filters

Biofilm samples from a carbonaceous trickling filter (TF) were evaluated in bench scale reactors to determine their maximum potential denitrification rates. Intact, undisturbed biofilms were placed into 0.6 L bench-scale reactors filled with sterilized, primary clarifier effluent spiked with nitrate to a final concentration of 16-18 mg/L as N. Dissolved oxygen concentrations were maintained between 2 and 4 mg/L in the bulk aqueous phase. Nitrate loss from the reactors was monitored over a 5h period. Denitrification rates of 3.09-5.55 g-N/m(2)day were observed with no initial lag period. This suggests that the capacity for denitrification is inherent in the biofilm and that denitrification can take place even when oxygen is present in the bulk aqueous phase. There were no significant differences in denitrification rates per unit area of media (g-N/m(2)day) either between (a). experimental runs or (b). sampling locations over the trickling filter. This suggests that denitrification potentials are uniform over the entire volume of the full-scale TF. For wastewater treatment plants with TFs that currently nitrify downstream, this approach may be used to meet less stringent permitted discharge concentrations and may allow some facilities to postpone or eliminate construction of additional unit processes for denitrification.     

NIR luminescent Er/Yb co-doped SiO2–ZrO2 nanostructured planar and channel waveguides: Optical and structural properties

Optical and structural properties of planar and channel waveguides based on sol–gel Er³⁺ and Yb³⁺ co-doped SiO₂–ZrO₂ are reported. Microstructured channels with high homogeneous surface profile were written onto the surface of multilayered densified films deposited on SiO₂/Si substrates by a femtosecond laser etching technique. The densification of the planar waveguides was evaluated from changes in the refractive index and thickness, with full densification being achieved at 900 °C after annealing from 23 up to 500 min, depending on the ZrO₂ content. Crystal nucleation and growth took place together with densification, thereby producing transparent glass ceramic planar waveguides containing rare earth-doped ZrO₂ nanocrystals dispersed in a silica-based glassy host. Low roughness and crack-free surface as well as high confinement coefficient were achieved for all the compositions. Enhanced NIR luminescence of the Er³⁺ ions was observed for the Yb³⁺-codoped planar waveguides, denoting an efficient energy transfer from the Yb³⁺ to the Er³⁺ ion.     

全尺寸深井钻井模拟装置对钻井技术发展的影响

缩短钻井周期是降低深井钻井成本和钻井风险的关键,这需要钻井新技术、新工艺、新材料、新工具的研究与应用,这必然要很大程度上依赖于大量的室内试验。斯伦贝谢Terra Tek钻完井实验室有全球最先进的全尺寸钻井模拟试验装置,在30多年间做了大量的模拟试验,试验结果对钻井技术发展、钻头设计、钻井液体系优选及性能优化起到了积极的促进作用。在介绍Terra Tek全尺寸钻井模拟试验装置的组成及主要功能的基础上,分析了该实验室在美国岩石力学协会钻井论坛、冲击钻井及深井钻井模拟试验中取得的主要成果,并介绍了该实验室在页岩气地层特点、开发技术和井眼稳定等方面取得的研究进展。      

Situation awareness: some conditions of possibility

Situation awareness (SA) has become a ubiquitous object of knowledge in our discourses of human performance and accident explanation. Based on Michel Foucault's archaeological approach, in this paper, we examine SA by mapping the ‘conditions of possibility’ for this object to emerge. By highlighting the logic that SA builds upon, the political need that it intends to address, and the knowledges that delimitate it in its constitution, we aim to display the contingent nature of this object. Ultimately, we argue that as a discursive object, SA has effects.     

The psychology of accident investigation: epistemological,preventive, moral and existential meaning-making

This paper extends research on accident investigation as exercises in political sensemaking, by considering the possible psychological meaning-making purposes of accident investigation. Accident investigations and reports serve epistemological or preventive aims: finding out what went wrong and avoiding recurrence. These are not necessarily the same: the variables that explain a particular event might diverge from those that help forestall a larger family of events. In addition, accident investigation serves moral and existential purposes. Accident investigations are (often implicitly) expected to render people's suffering accountable to reason and open to solution, prevention and elimination. The Western world tends to locate both the meaning and cause of suffering in the realm of human moral choice, which typically condenses accounts of failure down to single acts and actors. This competes with increasingly complex epistemological narratives of accidents that have neither obvious causes nor clear, linear cause–effect relationships.     

Drifting into failure: theorising the dynamics of disaster incubation

Ergonomic theory holds that accidents are preceded by periods of gradually increasing (but essentially unrecognised) risk, known originally in man-made disaster theory as the incubation period. This paper discusses the theorising of the dynamics of such accident incubation. It considers theoretical contributions – ranging from high-reliability to control theory to resilience engineering – for their ability to illuminate the driving forces behind a gradual shift in norms and erosion of safety margins, and for their ability to effectively track and represent such changes over time.     

A Numerical Study of the Performance of an Aerosol Sampler with a Curved,Blunt, Multi-Orificed Inlet

The purpose of this study was to numerically simulate the performance of an aerosol sampler with a curved, blunt, multi-orificed inlet in order to understand the sampling characteristics of the first prototype of the button personal inhalable aerosol sampler ("button sampler"). Because the button sampler inlet design is too complicated to apply a three-dimensional model, an axisymmetric two-dimensional model was created to be similar in geometry and to simulate the major features of the airflow through the sampler when facing the wind. Particle trajectories were calculated in a variety of wind velocities and were categorized into 5 groups based on their interactions with the curved surface of the sampling plane. Empirical sampling efficiencies of the button sampler for 3 particle sizes were used to adjust the calculated sampling efficiencies in an attempt to improve the accuracy of the two-dimensional axisymmetric model in accounting for interactions between particles and the surface of the inlet of the button sampler. Sampling efficiencies for other particle sizes were then predicted. The results showed that sampling efficiency decreased with increasing particle size up to approximately 40 w m and then remained virtually unchanged at about 35% up to 100 w m. Although the efficiencies were lower than the American Conference of Governmental Industrial Hygienists' (ACGIH) inhalability curve for larger particles, the pattern of the predicted sampling efficiency was quite similar to the ACGIH inhalability curve. Sampling efficiencies for liquid aerosol particles larger than 15 w m were predicted to be noticeably lower than those for solid particles. The results also showed that the multi-orificed curved surface played an important role in establishing a pressure drop with desired flow alignment inside the sampler, thus greatly reducing the wind effect and significantly improving the uniformity of particle deposition on the filter. The less uniform deposition found at high wind velocity can be improved by increasing the sampling flow rate.