1,720,953 research outputs found
Prediction of the terminal settling velocity of natural particles applied in drinking water treatment processes (PPT)
No full textpower point presentationSanitary Engineerin
Improvement of the Richardson-Zaki liquid-solid fluidisation model on the basis of hydraulics (PPT)
No full textOne of the most popular and frequently used models for describing homogeneous liquid-solid fluidised suspensions is the model developed by Richardson & Zaki in 1954. The superficial fluid velocity and terminal settling velocity together with an index, make it possible to determine the fluid porosity in a straightforward way. To maintain optimal process and control conditions in multiphase drinking water treatment processes, the porosity is kept relatively low. Unfortunately, the Richardson-Zaki index models tend to overestimate the minimum fluidisation velocity and therefore also result in less accurate predictions with respect to porosity values. We extended the Richardson-Zaki model with proven hydraulics-based models. The proposed models are compared with data from expansion experiments with grains applied in drinking water softening using the fluidised bed process. The porosity prediction error decreases from 15% to 3% and the minimum fluidisation velocity error from 100% to 12%.Sanitary Engineerin
Gezond drinkwater - een doorkijk door de tijd van gezond drinkwater: Masterclass M2 (PPT)
No full textVan een afstand in de ruimte ziet onze aarde er blauw uit. Je zou het daarom misschien niet verwachten, maar onze mooie planeet is toch heel erg droog. Met een toenemende wereldbevolking en een wens naar meer welvaart neemt de ‘water-stress’ steeds meer toe en dit betreft vooral zoet en schoon water.Het milieu wordt zwaarder belast met een scala aan chemische stoffen die op hun beurt een bedreiging vormen voor de volksgezondheid. Onze eerste primaire levensbehoefte is gezond drinkwater en dit vinden we in de westerse wereld heel vanzelfsprekend. Echter, op iets meer dan twee uur vliegen is het maar de vraag of het verstandig is om uit de kraan te drinken. In toenemende mate moeten er steeds complexere stoffen uit het water worden gehaald en dit vraagt steeds meer van de chemische zuiveringen bij de bereiding van drinkwater.In deze masterclass wordt aan de hand van de geschiedenis van Nederlands eerste waterleidingbedrijf uitgelegd hoe betrouwbaar drinkwater door de tijd heen werd bereid en hoe Nederland heden ten dage in staat is om het beste drinkwater van de wereld te bereiden. Ons drinkwater heeft vergelijkbare kwaliteit als flesjeswater alleen is het drinkwater uit de kraan veel goedkoper en duurzamer. Nederland als Deltaland, is een waterexpert en deelt en verspreidt deze kennis internationaal. Kennis dient te stromen.Deze masterclass gaat tevens in op het onderwerp duurzaamheid en drinkwater. Als wij willen dat volgende generaties ook zorgeloos uit de kraan kunnen blijven drinken moeten we duurzamer gaan werken. Waterbedrijven dragen hier al aan bij en vinden steeds betere oplossingen om de waterzuiveringsprocessen duurzaam te maken. De ontharding van drinkwater is hier een goed voorbeeld van. Bij het zachter maken van drinkwater worden er ook reststoffen geproduceerd. Van deze reststoffen worden nu weer nuttige grondstof van gemaakt en zo dragen we bij aan een circulaire economie. Naast de geschiedenis en de duurzaamheid gaat deze masterclass ook in op de processen van drinkwaterbereiding. De drinkwaterbereiding is een combinatie van zowel chemische, fysische als biologische processen en naast een circulaire aanpak ook een kwestie van een interdisciplinair aanpak. De masterclass “Gezond drinkwater - Een doorkijk door de tijd van gezond drinkwater” biedt u als docent kennis in diverse facetten van gezond drinkwater. De kennis die u bij deze masterclass op doet is heel geschikt om in uw eigen lespraktijk op uw eigen school uit te dragen.Sanitary Engineerin
Hydraulic modelling of liquid-solid fluidisation in drinking water treatment processes
No full textIn drinking water treatment plants, multiphase flows are a frequent phenomenon. Examples of such flows are pellet-softening and filter backwashing where liquid-solid fluidisation is applied. A better grasp of these fluidisation processes is needed to be able to determine optimal hydraulic states. In this research, models were developed, and experiments performed to gain such hydraulic knowledge. As a result, treatment processes can be made more flexible. In a rapidly changing environment, drinking water production must be flexible to ensure robustness and to tackle challenges related to sustainability and long-term changes. In the hydraulic models, the voidage in the fluidised bed and the particle size of the suspended granules are crucial variables. Voidage prediction is challenging as the fluidised bed is a dynamic environment showing highly heterogeneous behaviour that is hard to describe with an effective model. And particle size causes a conundrum due to the irregular shapes of the applied granules. Through the combination of hydraulic dimensionless Reynolds and Froude numbers, an accurate voidage prediction model has now been developed. With a straightforward pseudo-3D image analysis for non-spherical particles measuring particle mass and density, the dimensioned shapes of, for instance, ellipsoids can be determined. Particle shape factors included in models are not constant as is commonly believed, but dynamic. Applying advanced computational fluid dynamics simulations confirmed significant heterogeneous particle-fluid patterns in fluidised beds. Comprehensive sedimentation experiments showed that the average drag coefficient and terminal setting velocity of individual grains can be estimated reasonably well, but with a significant degree of data spread around the mean values. For engineering purposes, this is relevant information which should be taken into consideration. A new soft-sensor was designed to determine the voidage gradient and particle size profile in a fluidised bed. The expansion degree of highly erratic, polydisperse and porous granular activated carbon grains can be predicted with a model, but in full-scale processes the grains are subject to change, and therefore it is most likely that the prediction accuracy will deteriorate rapidly. For reliable drinking water quality, smart models provide solutions to complex challenges, but they are only effective when they are calibrated and validated in advanced pilot plants and are applied in full-scale processes with diligence and commitment on the part of multidisciplinary teams.Complex Fluid ProcessingSanitary Engineerin
Expansion Column Virtual Lab: Laboratory manual for liquid-solid fluidisation experiments
No full textA virtual lab (MOOC) for students chemical, civil or mechanical engineering. Students are introduced with a fluidised bed reactor (multiphase flow). This expansion column represents a liquid-solid fluidisation process applied in drinking water treatment processes. The knowledge you will gain will help you develop and improve your competence profile of a highly qualified chemical engineer.Students are informed with short lectures (films): https://doi.org/10.4121/12881009 and a manual (document). Several assignments must be completed based on recorded laboratory experiments.Complex Fluid Processin
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Videos of liquid-solid fluidisation experiments of calcite pellets and glass beads in water
No full text20 videos of liquid-solid fluidisation experiments in a university laboratory. You see a 5.7 cm PVC column where tap water is pumped in an upward direction causing particles to elevate into a fluidised state. Particles are calcite grains obtained from a full-scale drinking water softening reactor or perfectly round monodispersed glass beads. The reason to show these videos is to demonstrate that homogeneous flow regime not always occurs whilst this is often assumed regarding liquid-solid fluidisation systems. The viewer can observe open voids of water between the particles and water which choose a path of least resistance through the particle bed. Besides laminar-turbulent regime also homogeneous-heterogeneous distinction is relevant. These observations brought us to revise the standard drag relations used to predict the bed porosity
- …
