30 research outputs found
Parallelle sporen; stedelijke iconen als citybranding instrument
No full textNowadays it is almost impossible not to talk about citybranding within the practice of a city’s policy making. A growing number of municipalities are investing time and money in it by setting up websites, campaigns and organizing events. But also more extensive investments are being made in constructing visually dominant buildings. This research will investigate how cities can use these iconic buildings as citybranding instruments. Because of the limited knowledge that can be retrieved from literature, this is an ‘explorative research study’, in which knowledge is gained through the experiences of stakeholders. The necessary information will be gathered through a case study. This case study will focus on two iconic buildings located in a similar region, namely: The Hague New Central Station and Rotterdam Central Station. Both cases will first be examined on the basis of a document review. In addition to this, information will be gathered trough qualitative, open interviews with various stakeholders. This thesis is written in Dutch. However, there is an extensive English summary in the introduction.Urban Area DevelopmentReal Estate & HousingArchitecture and The Built Environmen
Using the Multiple Instance Learning framework to address differential regulation
No full textCell differentiation is a natural process occurring in all higher organisms, since the early fetal stage of life. It is, also, a part of disease – such as cancer – as the cell cycle becomes deregulated and cells behave differently compared to healthy ones. Differentiation occurs although the genome of all cells is identical across all cell types of the same organism. The motivation behind the current work is to understand why this happens. Cells differentiate because of different gene expression patterns. The genomic features close or around a gene determine its expression. One of these genomic features is the binding of Transcription Factors (TFs), which are proteins that bind in the promoter region of genes and are responsible for their (non-) expression. Other genomic features in?uence the binding of TFs close to genes, such as the accessibility of DNA, the levels of DNA methylation or the modi?cation of histones. The purpose of this study is to identify the genomic features that in?uence the binding of the TFs that are responsible for gene expression. Normal classi?cation cannot express that multiple TFs need to bind in a gene’s promoter region for it to be expressed and the number of TFs varies among genes. The TF labels are also unknown, meaning that it is not known which TF, or TFs, is/are responsible for gene expression. For these reasons, this problem – and the data – ?ts the Multiple Instance Learning (MIL) framework. A method is formulated, where a gene is treated as a bag and all the TF binding sites are instances. The results are promising, as TFs that were selected as important for gene expression were found to be so in a biological example.MSc Computer Science, Bioinformatics trackIntelligent SystemsElectrical Engineering, Mathematics and Computer Scienc
Intermediate stages of electrochemical oxidation of single-crystalline platinum revealed by in situ Raman spectroscopy
Get PDFUnderstanding the atomistic details of how platinum surfaces are oxidized under electrochemical conditions is of importance for many electrochemical devices such as fuel cells and electrolysers. Here we use in situ shell-isolated nanoparticle-enhanced Raman spectroscopy to identify the intermediate stages of the electrochemical oxidation of Pt(111) and Pt(100) single crystals in perchloric acid. Density functional theory calculations were carried out to assist in assigning the experimental Raman bands by simulating the vibrational frequencies of possible intermediates and products. The perchlorate anion is suggested to interact with hydroxyl phase formed on the surface. Peroxo-like and superoxo-like two-dimensional (2D) surface oxides and amorphous 3D α-PtO2 are sequentially formed during the anodic polarization. Our measurements elucidate the process of the electrochemical oxidation of platinum single crystals by providing evidence for the structure-sensitive formation of a 2D platinum-(su)peroxide phase. These results may contribute towards a fundamental understanding of the mechanism of degradation of platinum electrocatalysts.</p
Influence of chroma variations on naturalness and image quality of stereoscopic images
No full textThe computational view on image quality of Janssen and Blommaert states that the quality of an image is determined by the degree to which the image is both useful (discriminability) and natural (identifiability). This theory is tested by creating two manipulations. Firstly, multiplication of the chroma values of each pixel with a constant in the CIELab color space, i.e., chroma manipulation, is expected to increase only the usefulness by increasing the distances between the individual color points, enhancing the contrast. Secondly, introducing stereoscopic depth by varying the screen disparity, i.e., depth manipulation, is expected to increase both the usefulness and the naturalness. Twenty participants assessed perceived image quality, perceived naturalness and perceived depth of the manipulated versions of two natural scenes. The results revealed a small, yet significant shift between image quality and naturalness as a function of the chroma manipulation. In line with previous research, preference in quality was shifted to higher chroma values in comparison to preference in naturalness. Introducing depth enhanced the naturalness scores, however, in contrast to our expectations, not the image quality scores. It is argued that image quality is not sufficient to evaluate the full experience of 3D. Image quality appears to be only one of the attributes underlying the naturalness of stereoscopic images.Man-Machine InteractionElectrical Engineering, Mathematics and Computer Scienc
Competition and selectivity during parallel evolution of bromine, chlorine and oxygen on IrO<sub>x</sub> electrodes
Get PDFDuring hydrogen production for (renewable) energy storage, direct seawater electrolysis offers several notable advantages over freshwater electrolysis. Unfortunately, it is also hindered by possible oxidation reactions of chloride and (to a lesser extent) bromide, which can occur in parallel to the evolution of oxygen and form harmful by-products at the anode. Although the respective oxidation reactions of Br- and Cl- have been researched quite well on Pt, not much is known concerning bromide oxidation and its effect on the evolution of chlorine and oxygen for metal oxides, which are the class of electrocatalysts overwhelmingly used in industry. Using glassy carbon-supported iridium oxide (IrOx) as a model system, we investigated the oxidation behaviour of this well-known oxygen evolution catalyst in an acidic Br-/Cl- electrolyte. We first briefly discuss the solution chemistry and oxidation products that may be expected. Model studies were performed of the parallel evolution of Br2, Cl2 and O2 to increase the understanding of the anodic competition problem, with a special focus on the selectivity towards oxygen. Using rotating ring-disk voltammetry and UV–Vis spectroscopy, our results suggest that bromide and chloride competitively absorb on IrOx, but do not alter each other's oxidation reaction mechanisms, which both seem to adhere best to a Volmer-Heyrovský mechanism. We also find that bromide and chloride adsorption significantly slow down the oxygen evolution reaction, in an additive way. Even a relatively small amount of bromide highly affected the oxygen evolution selectivity. Formation of the interhalogen compound BrCl, which is possible in a mixed Br-/Cl- electrolyte, does not seem to occur.ChemE/Materials for Energy Conversion and Storag
A Novel Motion Detection Method Using 3D Discrete Wavelet Transform
No full textThe problem of motion detection has received considerable attention due to the explosive growth of its applications in video analysis and surveillance systems. While the previous approaches can produce good results, the accurate detection of motion remains a challenging task due to the difficulties raised by illumination variations, occlusion, camouflage, sudden motions appearing in burst, dynamic texture, and environmental changes such as those on weather conditions, sunlight changes during a day, etc. In this study, a novel per-pixel motion descriptor is proposed for motion detection in video sequences which outperforms the current methods in the literature particularly in severe scenarios. The proposed descriptor is based on two complementary three-dimensional discrete wavelet transforms (3D-DWT) and a three-dimensional wavelet leader. In this approach, a feature vector is extracted for each pixel by applying a novel three-dimensional wavelet-based motion descriptor. Then, the extracted features are clustered by the well-known K-means algorithm. The experimental results demonstrate the effectiveness of the proposed method compared to state-of-the-art approaches in several public benchmark datasets. The application of the proposed method and additional experimental results for several challenging datasets are available online.This article has been accepted for publication in a future issue of this journal, but has not been fully edited. Content may change prior to final publication.Pattern Recognition and Bioinformatic
Competition and Interhalogen Formation during Parallel Electrocatalytic Oxidation of Bromide and Chloride on Pt
Get PDFHydrogen production from seawater electrolysis is highly promising for the capture and storage of intermittent renewable energy, but is hindered by the possibility of unwanted reactions at the anode. The oxidation reactions of chloride and (to a lesser extent) bromide, which can occur in parallel to the evolution of oxygen, lead to environmentally harmful by-products and thus represent undesirable side-reactions. We present some general considerations of solution chemistry and oxidation products that may be expected in a mixed acidic bromide/chloride electrolyte. We performed electrochemical model studies of the simultaneous oxidation of bromide and chloride and their mutual interaction on a Pt electrocatalyst, with the aim of deepening the general understanding of the anodic competition problem. Using simplified model systems, our findings suggest that the oxidation of bromide is hindered by competing chloride adsorption, in a way that can be quite satisfactorily modelled by a simple Langmuir isotherm describing the competing adsorption and reactivity of all species. The oxidation of chloride was however not properly captured by this same model, and may be substantially different. Furthermore, the formation of the interhalogen compound BrCl seems to occur in-between the oxidation of bromide and chloride.ChemE/Materials for Energy Conversion and Storag
Iridium-based double perovskites for efficient water oxidation in acid media
Get PDFThe development of active, cost-effective and stable oxygen-evolving catalysts is one of the major challenges for solar-to-fuel conversion towards sustainable energy generation. Iridium oxide exhibits the best available compromise between catalytic activity and stability in acid media, but it is prohibitively expensive for large-scale applications. Therefore, preparing oxygen-evolving catalysts with lower amounts of the scarce but active and stable iridium is an attractive avenue to overcome this economical constraint. Here we report on a class of oxygen-evolving catalysts based on iridium double perovskites which contain 32 wt% less iridium than IrO2 and yet exhibit a more than threefold higher activity in acid media. According to recently suggested benchmarking criteria, the iridium double perovskites are the most active catalysts for oxygen evolution in acid media reported until now, to the best of our knowledge, and exhibit similar stability to IrO2.ChemE/Catalysis Engineerin
Visual discomfort in stereoscopic dsplays: A review
No full textVisual discomfort has been the subject of considerable research in relation to stereoscopic and autostereoscopic displays, but remains an ambiguous concept used to denote a variety of subjective symptoms potentially related to different underlying processes. In this paper we clarify the importance of various causes and aspects of visual comfort. Classical causative factors such as excessive binocular parallax and accommodation-convergence conflict appear to be of minor importance when disparity values do not surpass one degree limit of visual angle, which still provides sufficient range to allow for satisfactory depth perception in consumer applications, such as stereoscopic television. Visual discomfort, however, may still occur within this limit and we believe the following factors to be the most pertinent in contributing to this: (1) excessive demand of accommodation-convergence linkage, e.g., by fast motion in depth, viewed at short distances, (2) 3D artefacts resulting from insufficient depth information in the incoming data signal yielding spatial and temporal inconsistencies, and (3) unnatural amounts of blur. In order to adequately characterize and understand visual discomfort, multiple types of measurements, both objective and subjective, are needed.Man-Machine InteractionElectrical Engineering, Mathematics and Computer Scienc
Effects of Substrate and Polymer Encapsulation on CO<sub>2</sub> Electroreduction by Immobilized Indium(III) Protoporphyrin
No full textHeterogenization of molecular catalysts for CO2 electroreduction has attracted significant research activity, due to the combined advantages of homogeneous and heterogeneous catalysts. In this work, we demonstrate the strong influence of the nature of the substrate on the selectivity and reactivity of electrocatalytic CO2 reduction, as well as on the stability of the studied immobilized indium(III) protoporphyrin IX, for electrosynthesis of formic acid. Additionally, we investigate strategies to improve the CO2 reduction by tuning the chemical functionality of the substrate surface by means of electrochemical and plasma treatment and by catalyst encapsulation in polymer membranes. We point out several underlying factors that affect the performance of electrocatalytic CO2 reduction. The insights gained here allow one to optimize heterogenized molecular systems for enhanced CO2 electroreduction without modification of the catalyst itself.ChemE/Catalysis Engineerin
