CFD Modelling of Micromixing in a T-mixer with Square Bends

International audienceCFD simulations are performed to study the micro-mixing in a T-mixer with square bends by using the Villermaux-Dushman reaction. The calculated segregation indices are compared with previously published data and it is shown that whilst the trend is capture the simulation overpredict the extent of miccromixing. This paper provides guidance on the computational requirements needed to obtain accurate results in such laminar flows and shows the complex species fields that develop within the reactor

Characterization of micromixing in a Continuous Oscillatory Baffled Reactor

International audienceMicromixing is the limiting step in the progress of fast reactions and fast crystallization processes. Micromixing performance of a Nitech© glass COBR has been characterized using the competing parallel iodide-iodate test reactions. Macromixing length was also qualitatively determined by visualization of a tracer. The results show that an increase in the amplitude to baffle space ratio and a decrease of oscillation frequency improves mixing performance

ROBUST TECHNIQUES FOR BUILDING FOOTPRINT EXTRACTION IN AERIAL LASER SCANNING 3D POINT CLOUDS

The building footprint is crucial for a volumetric 3D representation of a building that is applied in urban planning, 3D city modeling, cadastral and topographic map generation. Aerial laser scanning (ALS) has been recognized as the most suitable means of large-scale 3D point cloud data (PCD) acquisition. PCD can produce geometric detail of a scanned surface. However, it is almost impossible to get point clouds without noise and outliers. Besides, data incompleteness and occlusions are two common phenomena for PCD. Most of the existing methods for building footprint extraction employ classification, segmentation, voting techniques (e.g., Hough-Transform or RANSAC), or Principal Component Analysis (PCA) based methods. It is known that classical PCA is highly sensitive to outliers, even RANSAC which is known as a robust technique for shape detection is not free from outlier effects. This paper presents a novel algorithm that employs MCMD (maximum consistency within minimum distance), MSAC (a robust variant of RANSAC) and a robust regression to extract reliable building footprints in the presence of outliers, missing points and irregular data distributions. The algorithm is successfully demonstrated through two sets of ALS PCD

Impact of thixotropy on flow patterns induced in a stirred tank : numerical and experimental studies

Agitation of a thixotropic shear-thinning fluid exhibiting a yield stress is investigated both experimentally and via simulations. Steady-state experiments are conducted at three impeller rotation rates (1, 2 and 8 s−1) for a tank stirred with an axial-impeller and flow-field measurements are made using particle image velocimetry (PIV) measurements. Threedimensional numerical simulations are also performed using the commercial CFD code ANSYS CFX10.0. The viscosity of the suspension is determined experimentally and is modelled using two shear-dependant laws, one of which takes into account the flow instabilities of such fluids at low shear rates. At the highest impeller speed, the flow exhibits the familiar outward pumping action associated with axial-flow impellers. However, as the impeller speed decreases, a cavern is formed around the impeller, the flow generated in the vicinity of the agitator reorganizes and its pumping capacity vanishes. An unusual flow pattern, where the radial velocity dominates, is observed experimentally at the lowest stirring speed. It is found to result from wall slip effects. Using blades with rough surfaces prevents this peculiar behaviour and mainly resolves the discrepancies between the experimental and computational results

Predicted vs. measured paraspinal muscle activity in adolescent idiopathic scoliosis patients: EMG validation of optimization-based musculoskeletal simulations.

Musculoskeletal (MSK) models offer great potential for predicting the muscle forces required to inform more detailed simulations of vertebral endplate loading in adolescent idiopathic scoliosis (AIS). In this work, simulations based on static optimization were compared with in vivo measurements in two AIS patients to determine whether computational approaches alone are sufficient for accurate prediction of paraspinal muscle activity during functional activities. We used biplanar radiographs and marker-based motion capture, ground reaction force, and electromyography (EMG) data from two patients with mild and moderate thoracolumbar AIS (Cobb angles: 21° and 45°, respectively) during standing while holding two weights in front (reference position), walking, running, and object lifting. Using a fully automated approach, 3D spinal shape was extracted from the radiographs. Geometrically personalized OpenSim-based MSK models were created by deforming the spine of pre-scaled full-body models of children/adolescents. Simulations were performed using an experimentally controlled backward approach. Differences between model predictions and EMG measurements of paraspinal muscle activity (both expressed as a percentage of the reference position values) at three different locations around the scoliotic main curve were quantified by root mean square error (RMSE) and cross-correlation (XCorr). Predicted and measured muscle activity correlated best for mild AIS during object lifting (XCorr's ≥ 0.97), with relatively low RMSE values. For moderate AIS as well as the walking and running activities, agreement was lower, with XCorr reaching values of 0.51 and comparably high RMSE values. This study demonstrates that static optimization alone seems not appropriate for predicting muscle activity in AIS patients, particularly in those with more than mild deformations as well as when performing upright activities such as walking and running

HAMAP in 2015: updates to the protein family classification and annotation system.

HAMAP (High-quality Automated and Manual Annotation of Proteins-available at http://hamap.expasy.org/) is a system for the automatic classification and annotation of protein sequences. HAMAP provides annotation of the same quality and detail as UniProtKB/Swiss-Prot, using manually curated profiles for protein sequence family classification and expert curated rules for functional annotation of family members. HAMAP data and tools are made available through our website and as part of the UniRule pipeline of UniProt, providing annotation for millions of unreviewed sequences of UniProtKB/TrEMBL. Here we report on the growth of HAMAP and updates to the HAMAP system since our last report in the NAR Database Issue of 2013. We continue to augment HAMAP with new family profiles and annotation rules as new protein families are characterized and annotated in UniProtKB/Swiss-Prot; the latest version of HAMAP (as of 3 September 2014) contains 1983 family classification profiles and 1998 annotation rules (up from 1780 and 1720). We demonstrate how the complex logic of HAMAP rules allows for precise annotation of individual functional variants within large homologous protein families. We also describe improvements to our web-based tool HAMAP-Scan which simplify the classification and annotation of sequences, and the incorporation of an improved sequence-profile search algorithm

Compliance with mandatory standards in agriculture : a comparative approach of the EU vis-à-vis the United States, Canada and New Zealand

This report presents some of the interim results of the project 'Facilitating the CAP reform: Compliance and competitiveness of European agriculture'. It summarises and integrates the implementation of cross compliance measures in seven EU countries (France, Germany, Italy, Netherlands, United Kingdom, Spain and Poland), with a particular focus on the degree of compliance and the costs of compliance. Also, the implementation of similar measures is examined in three non-EU countries (Canada, United States and New Zealand)

Time to look for evidence : Results-based approach to biodiversity conservation on farmland in Europe

Increased use of annual payments to land managers for ecological outcomes indicates a growing interest in exploring the potential of this approach. In this viewpoint, we drew on the experiences of all schemes paying for biodiversity outcomes/results on agricultural land operating in the EU and EFTA countries with the aim of reviewing the decisive elements of the schemes' design and implementation as well as the challenges and opportunities of adopting a results-based approach. We analysed the characteristics of results-based schemes using evidence from peer-reviewed literature, technical reports, scheme practitioners and experts in agri-environment-climate policy. We developed a typology of the schemes and explored critical issues influencing the feasibility and performance of results-based schemes. The evidence to date shows that there are at least 11 advantages to the results-based approach not found in management-based schemes with similar objectives, dealing with environmental efficiency, farmers' participation and development of local biodiversity-based projects. Although results-based approaches have specific challenges at every stage of design and implementation, for many of these the existing schemes provide potential solutions. There is also some apprehension about trying a results-based approach in Mediterranean, central and eastern EU Member States. We conclude that there is clear potential to expand the approach in the European Union for the Rural Development programming period for 2021-2028. Nevertheless, evidence is needed about the approach's efficiency in delivering conservation outcomes in the long term, its additionality, impact on the knowledge and attitudes of land managers and society at large, development of ways of rewarding the achievement of actual results, as well as its potential for stimulating innovative grassroots solutions.Peer reviewe

Exploring the synergies between cross compliance and certification schemes

This report presents some of the interim results of the project 'Facilitating the CAP reform: Compliance and competitiveness of European agriculture'. It examines the similarities and differences between mandatory cross compliance standards and those set by voluntary certification schemes. There is a potential synergy between cross compliance and certification schemes, not least because both approaches set minimum standards and enforce those standards through inspection systems. Although there are some strong limitations, there is sufficient overlap in the standards set and in approaches to control to warrant further investigation of the potential for the harmonisation of standards and collaborative approaches to control