46 research outputs found
Systematic review data of Brons et al. (2024)
No full textSystematic review data for Brons, A., Wang, S., Visser, B., Kröse, B., Bakkes, S., & Veltkamp, R. (2024). Machine Learning Methods to Personalize Persuasive Strategies in mHealth Interventions That Promote Physical Activity: Scoping Review and Categorization Overview. Journal Of Medical Internet Research, 26, e47774. https://doi.org/10.2196/4777
Dynamics of finite-sized light spheres in turbulence
No full textWe report experimental results on the Lagrangian dynamics of finite-size light particles in turbulence. Using an orthogonal camera setup and 3D particle tracking, we study the velocity and acceleration statistics of rigid light spheres in a water tunnel with nearly homogeneous and isotropic turbulence. The Reynolds number (ReY) is varied from 180 to 300, and the study covers a range of size ratios (4 < D/η < 16) for marginally light spheres. We find that the normalised acceleration PDF decreases in intermittency with increasing size ratio - in qualitative agreement with the predictions of the Faxén corrected model. We also present preliminary results on the rotational dynamics of large light spheres in turbulence
Konditionsgranskning av parkbroar i trä
No full textExamensarbetet omfattar konditionsgranskning av Pargas stads parkbroar i trä. Broarna har stor betydelse för den lätta trafiken och binder samman Pargas centrum på tre olika ställen. Examensarbetet har skett i samarbete med Pargas stad och har tyngdpunkten på konditionsgranskningen.
Examensarbetet behandlar även kortfattat träbroar i allmänhet samt ger en inblick i historien om Pargas träbroar i den mån det gått att hitta information.
Målet med examensarbetet var att göra en grundlig genomgång av träbroarnas kondition och ge förslag på vad som möjligen kan åtgärdas. Konditionen i sig var inte överraskande, men en grundlig genomgång har gett en noggrann inblick i broarnas kondition i dagsläget.
Examensarbetet omfattar undersökning med resistograf. Med tillförlitliga mätningar kan en plan för renovering och möjligt förnyande av broarna göras.
Beställning av den nya bron över Pargas centralparks damm ingick även i arbetet. Offertförfrågan är gjord på nya limträbalkar och en offert har lett till beställning.
Resultatet av detta examensarbete är en rapport över tre av fyra parkbroar i trä i Pargas och ett beslut om att förnya den fjärde bron sommaren 2023. Den nya brons första idéskiss finns med i detta arbete och ger en överblick över hur den nya bron kommer att se ut.
The aim of this Bachelor’s thesis was been to conduct an inspection of the condition of the timber bridges in the parks in Pargas. The bridges combine Pargas’ downtown for light traffic on three locations. The thesis was a cooperation with the city of Pargas and the focus was on the review of the bridges. The thesis also included an overview of timber bridges in general and provided some history of Pargas’ timber bridges.
The purpose of the thesis was to conduct a thorough inspection of the bridges’ condition and to make suggestions for further actions. The condition of the bridges was not a surprise, but a thorough review gave a deep insight into the conditions of bridges today.
The thesis work includes an inspection made with a Resistograph. With reliable measurements a plan can be made for renovation and possible re-building of the bridges.
The ordering of a new timber bridge over the pond in the Central park of Pargas was also included in this thesis. Offer requests for new timber beams have been received and one led to an order.
The result of this thesis was a condition-report over three out of four timber bridges in Pargas. A decision to rebuild the pond bridge in the summer of 2023 was made based on the results. The first sketch of the new bridge was included in this thesis and provided an idea how the new bridge will be built
How to support Gen-Y consumers to start investing sustainably
No full textInvesting has become a hot topic among the younger generation since the Covid-19 crisis. However, much of its potential is still unused, as seen in a big group of the younger generation which is positive to start but procrastinates this decision. While this younger generation would like to make a positive impact with their money on the environment of the planet earth, the existing investing propositions aren’t helping them with that sustainable mission. In this thesis, I researched how Rabobank can help this group of young non-investors start investing, but with a sustainable focus. Creating a win-win situation for the non-investor who gets motivated to start investing consciously while at the same time helping them to fulfil their sustainable ambitions.To access the showcase use the following link: https://xd.adobe.com/view/1adcd6dd-4439-42e3-99e2-accc30bcbe44-4f8f/?fullscreenStrategic Product Desig
Stroming tijdens centrifugaalgieten: Experimenten en simulaties
No full textGieterij Metagis B.V. in Ridderkerk giet bronzen bussen met een lengte van 1.22 m en een maximum diameter van 500 mm in een centrifugaalgietmachine. Het vloeibare brons wordt onder een hoek van 30° aan de kopse kant in de roterende horizontale coquille gegoten en door de centrifugaalkracht tegen de wand gedrukt alwaar het zich verdeelt en stolt. Het gieten van dunwandige bussen geeft problemen, omdat het brons stolt voordat er een uniforme laagdikte is ontstaan. In dit onderzoek zijn in een perspex schaalmodel van de gietmachine gietingen met water gedaan om het stromingsgedrag in een roterende coquille zonder stolling te bestuderen. Twee optische meetmethoden zijn ontwikkeld om de snelheid van het vloeistoffront en de laagdikte-ontwikkeling te meten. De eerste methode meet de frontsnelheid als functie van het toerental en het debiet door het vloeistoffront tijdens het vullen te filmen. Daarnaast is met dimensieanalyse voor een twee-dimensionale stationaire benadering van de stroming afgeleid dat de frontsnelheid evenredig is met het toerental tot de macht 2/3. Deze relatie wordt binnen zekere nauwkeurigheidsmarges achter in de coquille, waar de inlaat geen invloed meer heeft op de stroming, bevestigd door de experimenten. De gieüngen werden zonder axiale beginimpuls, onder 90°, gedaan. Om de invloed van de beginimpuls op de frontsnelheid te bepalen zijn er ook gietingen onder 30° verricht. De tweede meetmethode, gebaseerd op extinctie van laserlicht, is ontwikkeld om het laagdikteverloop in tijd en plaats tijdens en na een gieüng te bepalen. De aandacht richtte zich hierbij onder andere op de invloed van de inlaat op de stroming en op oppervlaktegolven. Met de CFD-code FL0W-3D zijn twee-dimensionale vlakke stromingen gesimuleerd, waarbij de centrifugaalkracht als zwaartekracht geïmplementeerd is. Er is zowel stroming van water als van vloeibaar brons gesimuleerd. Stolling is hierbij nog niet meegenomen. Voor gietingen met water zijn de berekende frontsnelheden vergeleken met de gemeten waarden en deze vertonen goede overeenkomst.Kramers Laboratorium voor Fysische TechnologieApplied Science
De bereiding van azijnzuuranhydride uit methanol en koolmonoxide
No full textDocument(en) uit de collectie Chemische Procestechnologie.DelftChemTechApplied Science
Design of a hydraulic transmission system with series elastic element for a knee joint gait training application
No full textThe restoration of the walking function of paraplegic patients requires long and extensive training. Physicians themselves are not able to provide this training due to the physical labour required. Robots and soft exoskeletons are in development to assist the physicians in this task, however, they are either bulky and restrictive or lack a method to actuate the knee joint. This research explores if a hydraulic system with elastic element is able to actuate a human knee joint during gait training.The hydraulic system is required to provide a torque of 75Nm with a bandwidth of 4Hz, the large force bandwidth, and a torque of 20Nm over a bandwidth of 12Hz, the small force bandwidth. The system must fit on a knee joint and impose the least amount of restrictions on the patient. Concepts that were identified as possible solutions in a previous literature review included a hydrostatic transmission, a system with a master rotary pump and a rotary slave actuator, a dual-acting hydraulic cylinder, and a master slave hydraulic cylinder system. Preliminary open loop simulation results suggest that the Hydrostatic transmission could give better performance in Torque transmission, size, and complexity. The bandwidth performance for both concepts was equal.The simulation model of the hydrostatic concept is expanded to include DC motor/driver dynamics, knee dynamics in swing phase, and ground reaction forces in stance phase. A physical test bed is designed to evaluate the simulation results with a real-world counterpart.Open loop and closed loop with PI controller results showed a significant decrease in the output torque magnitude for the real-world system, up to a factor 13 smaller. The output torque is decreased by the higher friction, slow pressure build-up and leakages in the real-world system. These factors are in part caused by the design choices made for the test bed design, such as the over-the-counter parts and usage of a 3D printed spring. Failure of the spring was observed at high torque and low frequency input signal. This was made worse by the large initial overshoot of the system in the closed loop tests. A more precise control scheme than the PI controller should be designed to prevent breakage. The real-world system is stable and the bandwidth of the system was larger than the 4Hz that is required for the application. For future research a smaller custom hydraulic loop will need to be created to alleviate the friction and leakage issues. Only then will a hydraulic system with series elastic element actuate a human knee to help a paraplegic patient walk again.Mechanical Engineering | BioMechanical Desig
Electrostatically Enhanced Granular Bed Filtration: Choosing Materials + Filter Modelling
No full textAs a part of the project on Pressurized Fluidized bed Combustion of Coal / High Temperature Gas Cleaning, a six-month period was spent investigating a number of granular materials on their applicability as granular material in an Electrostatically Enhanced Granular Bed Filter, to be applied as the final cleaning step of the off-gas. Impedance Spectroscopy was used as technique to obtain information on the electrical behaviour of the materials in AC electric fields. Quartz granules showed a conductivity of 1-2 orders of magnitude greater than alumina granules, both with and without fly ash loadings. Barium titanate still remains an interesting material, despite its high-power consumption. Pelletized BaTiO3 granules should be investigated in the near future. The existing EV-model for granular bed filtration was scrutinized, modified and translated from Fortran to Pascal to yield an interactive and user-friendly program for the PC. The model is now expected to give reliable information on filtering efficiencies and the transition between surface filtration and deep bed filtration.Applied SciencesChemical EngineeringParticle Technology Grou
