193 research outputs found
Toekomstvisies van jonge architecten: De bibliotheek als denkbeeld
No full textStudenten van de TU Eindhoven kregen de opdracht een bibliotheek te ontwerpen die een
centrale rol kan vervullen op de campus. Daan Koch, Patricia van den Eertwegh en Dave van
den Berg werden uitgekozen om hun ontwerp te presenteren tijdens het symposium ‘Het
gebouw als denkbeeld’ op 20 november jl. Hun ontwerpen hebben een aspect gemeen: zij
staan niet alleen ten dienste van informatie, maar ook voor ontspanning en ontmoeting
A Steerable Stylet for the Transjugular Intrahepatic Portosystemic Shunt Procedure
No full textIn recent years, more and more medical operations are done minimally invasive. Intervention radiology is a medical specialty which uses minimally invasive techniques to diagnose, or treat diseases. Instruments like needles and catheters are used by radiologists to enter the network of veins and arteries guided by image modalities. A complex treatment in the interventional radiology is the Transjugular Intrahepatic Portosystemic Shunt (TIPS) procedure. This treatment is developed for people who suffer from liver cirrhosis which are not eligible for liver transplantation. The problem which arise with a liver affected by cirrhosis is that it can not transmit enough blood. Without transplantation or a treatment this will eventually lead to death. During the TIPS procedure a connection is made between the right hepatic and the portal vein by a shunt. As a result, blood pressure reduction in the portal system since the blood can flow back to the right atrium of the heart, bypassing the liver.The hardest part in a TIPS procedure is the intrahepatic puncture between the hepatic and portal vein. The interventional radiologist tries to enter the portal vein by puncturing a small stylet from the hepatic vein through the liver tissue. Due to cirrhosis the liver tissue is very stiff and stylet deflection will occur. To reduce the uncertainty of entering the portal vein, this thesis is focused on designing a stylet that is more stiff and able to steer. It is expected that the complexity of the procedure will be reduced and a higher hit rate to enter the portal vein will be achieved.\\ \\The prototype of the steerable stylet has been evaluated through various experiments, a visibility test and with procedures in a test liver model. During these experiments the steering characteristics, the stiffness of the stylet, the maximum lateral forces exerted by the tip while steering, the influence of the stylet orientation and the visibility are obtained. Afterwards, an evaluation was done in a liver model, made of PVA, to determine whether the stylet is capable to reduce the complexity of the intrahepatic puncture step in the TIPS procedure.With the prototype made in this graduation project, based on a steerable ablation needle, the complexity of the TIPS procedure is not reduced yet. The steerable stylet was not able to enter the portal vein. It was already hard to enter the right hepatic vein since the pre-bent stiffening cannula was adapted with a smaller angle which was necessary since the steerable stylet was too stiff to push through the pre-bent angle. According to this prototype, possibilities are shown to use a mechanical steering mechanism in instruments with a long thin shaft. The transmission in combination with the joint mechanisms fits within 1.3mm diameter, was able to bridge 60cm from distal end to proximal end and had only 4 components, the stylet, the rigid cannula, the key to fix the stylet to the rigid cannula and the transmission. By translating the stylet in a push or pull direction relative to the rigid cannula, steering angles could be achieved. With further research and development this steering mechanism must be able to steer the required amount of degrees without any extra components, is well visible with ultrasound, and is good resistant against lateral forces. Mechanical Engineering | BioMechanical Desig
Modelling and Control of a Fall-Pipe System
No full textA Fall-Pipe system deposits rock on the seabed for the protection of submerged objects. Due to the irregular motion of a vessel on the waves the accuracy and efficiency of the rock dumping process is limited. This thesis develops a motion compensation system for a modular Fall-Pipe system developed by Vuyk Engneering. From literature it appears motion compensation on a semi-submerged system is a novel application. Therefore the approach taken in this thesis is to establish a working motion compensation system based on broadly used methods. This results in selection of the Newton-Euler method for modelling the dynamics of the system and the selection of an LQR controller for feedback control. A proof of concept is performed on a 2D representation of the system. This proves the controller type and modelling method are both applicable to the problem and yield satisfactory results. Furthermore a baseline can be established from which to expand and improve. The full system dynamics are then modelled and simulated. Following this simulation it is observed that the performance of the motion compensation system is limited by the first order movement of the vessel, the inertia of the Fall-Pipe and the hydrodynamic forces acting on the system. An improved feedforward controller, which aims to retain the Fall-Pipe tip position, is applied in conjunction with a tuned LQR controller. The final motion compensation system eliminates the second order movement of the vessel and attenuates the first order movement to retain the Fall-Pipe tip position within 0.5 meters of the desired trajectory. This ensures the position of the Fall-Pipe at all times, therefore the material cost and time required to ensure a proper rock bed is decreased.Mechanical Engineering | Systems and Contro
Universally Hard Hamiltonian Cycle Problem Instances
Full text linkIn 2021, evolutionary algorithms found the hardest-known yes and no instances for the Hamiltonian cycle problem. These instances, which show regularity patterns, require a very high number of recursions for the best exact backtracking algorithm (Vandegriend-Culberson), but don't show up in large randomized instance ensembles. In this paper, we will demonstrate that these evolutionarily found instances of the Hamiltonian cycle problem are hard for all major backtracking algorithms, not just the Vandegriend-Culberson. We compare performance of these six algorithms on an ensemble of 91,000 randomized instances plus the evolutionar-ily found instances. These results present a first glance at universal hardness for this NP-complete problem. Algorithms, source code, and input data are all publicly supplied to the community
Zastoupení v holandské identitární politice: prozkoumávání strategické role politických stran
No full textIn recent years, Dutch identity politics has become a topic of increasing interest and scrutiny, as various political parties seek to represent and promote the interests of different identity groups. In this context, understanding the strategical role of political parties in shaping representation is crucial. This thesis explores how the strategy of Dutch political parties influence their ability to shape representation in identity politics. Using qualitative methods, including process-tracing and the analyses of relevant documents and media, this thesis examines the strategies employed by political parties in order to achieve political representation. Specifically, this thesis analyses the ways in which political parties impact the effectiveness of representation efforts, and identify key factors that contribute to successful political representation. The findings suggest that the approach of the political party is a critical factor in shaping representation in Dutch identity politics, and that an identity-based approach is necessary in order to effectively advocate for marginalised identity groups. This thesis contributes to a deeper understanding of the complex dynamics of Dutch identity politics and provides insights for policymakers, activists and scholars seeking to engage with the issue.Katedra evropských studiíDepartment of European StudiesFaculty of Social SciencesFakulta sociálních vě
Representation in Dutch Identity Politics: Exploring the Strategical Role of Political Parties
No full textIn recent years, Dutch identity politics has become a topic of increasing interest and scrutiny, as various political parties seek to represent and promote the interests of different identity groups. In this context, understanding the strategical role of political parties in shaping representation is crucial. This thesis explores how the strategy of Dutch political parties influence their ability to shape representation in identity politics. Using qualitative methods, including process-tracing and the analyses of relevant documents and media, this thesis examines the strategies employed by political parties in order to achieve political representation. Specifically, this thesis analyses the ways in which political parties impact the effectiveness of representation efforts, and identify key factors that contribute to successful political representation. The findings suggest that the approach of the political party is a critical factor in shaping representation in Dutch identity politics, and that an identity-based approach is necessary in order to effectively advocate for marginalised identity groups. This thesis contributes to a deeper understanding of the complex dynamics of Dutch identity politics and provides insights for policymakers, activists and scholars seeking to engage with the issue
Classical Benchmark Functions, But Harder
Full text linkWe explore the hardness evolvability of 12 well-known continuous benchmark test functions such as Schwefel, Griewank and Goldstein-Price, by evolutionarily retuning their numeric parameters. Evaluation is done by assessing the hardness of optimzation for the plant propagation algorithm (PPA), a crossoverless evolutionary method. The evolutionary process has a significant effect on a function’s objective landscape (“Fitness landscape” is the more common term, but “objective landscape” is correcter, as some algorithms actively process objective values into fitness values.) and the resulting hardness for PPA. When assessing at the resulting landscapes, three distinct patterns of evolution are observed: concave-to-convex inversion, global minimum narrowing, and increase in ruggedness. Conclusively, many of these traditional benchmark functions are not nearly as hard as the could be, at least for one metaheuristic optimization algorithm. As it turns out, traditional benchmark functions can be made much more challenging by only retuning a few of their constants. Some limitations and future options are discussed.</p
Randomness in Local Optima Network Sampling
No full textWe consider statistical randomness in the construction of local optima networks (LONs) and conduct a preliminary and exploratory study into this. LONs capture a fitness landscape into network format: the nodes are local optima, and edges are heuristic search transitions between them. Problem instances from the benchmark quadratic assignment problem library are used in the analysis. LONs are constructed using an iterated local search (ILS) and several different random seeds. Metrics are computed from the networks and visualised to assess the effect of randomness. Algorithm performance models for ILS runtime are built using metrics of LONs constructed using different seeds and the results compared. The results show that some LON metrics seem consistent across seeds, while others vary substantially. Additionally, the quality of algorithm performance models using LON metrics as predictors can differ depending on randomness. Finally, LON metrics associated with separate seeds can lead to different algorithm configuration recommendations for the same instance.Output Status: Forthcomin
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