52 research outputs found
SJORS: A Semantic Recommender System for Journalists
No full textRecommender Systems support a broad range of domains, each with peculiarities that recommendation algorithms must consider to produce appropriate suggestions. In the paper, we bring attention to a little-studied scenario related to the news domain: recommendations catering to media journalists. Based on the particular needs inherent to a newsroom, the authors introduce SJORS, a wire news Recommender System that takes into account the activities of each journalist as well as other critical factors that arise in this particular domain, such as wire news recency. Given the nature of the items recommended, SJORS deals with the inherent ambiguity of natural language by exploiting different semantic techniques and technologies. The authors have conducted several experiments in a media company, which validated the performance and applicability of the system. Outcomes emerging from this work could be extended to other domains of interest, such as online stores, streaming platforms, or digital libraries, to name a few.Web Information System
Functional genomics analysis of the secretory pathway in Aspergillus niger
No full textFilamentous fungi can be found in the majority of habitats of our planet. The wide-spread presence of filamentous fungi is related to their versatile metabolism, which allows them to grow on simple substrates, such as nitrate, acetate, ethanol, ammonia, or on complex matter such as biopolymers from plant or animal tissues. In order to grow on complex biopolymers such as plant cell wall polysaccharides, fungi must secret hydrolytic and modifying enzymes. These enzymes allow polysaccharide degradation and subsequent internalization of simpler molecules, such as sugar monomers. The filamentous fungus Aspergillus niger has been the subject of intense research in the past decades. This organism is responsible for the largest production of citric acid worldwide. In addition to this, A. niger produces high amounts of enzymes with important applications in the bioindustry, such as enzymes for food and feed processing, or enzymes used for the simultaneous saccharification and fermentation of cellulose for bioethanol production. The secretion of extracellular enzymes in A. niger has been mostly focused on the prediction of gene function based on genome annotation and on the analysis of gene expression. However, there is a gap in the knowledge of all the proteins present in cell, given by proteomics. The aim of the work presented in this thesis was to use a functional genomics approach to identify genes and proteins involved in protein secretion in A. niger and to investigate the dynamic changes of the secretory proteome under high-secretion conditions. For this purpose, we used a combination of gene expression profiling with shotgun proteomics of secretory organelles. Chapter 2 describes a method for gene silencing in filamentous fungi via RNA interference. This method makes use of vectors which express long hairpin RNAs. In A. niger, gene knock-out strategies have been the main method for the determination of gene function. These strategies have proven to be particularly useful when carried out in strains with defective pathways for non-homologous integration, such as the kusA mutant. Nevertheless, a gene knock-down strategy such as the one described in chapter 2 could be relevant for the study of gene function, for two reasons: a) essential genes could be studied as RNAi does not necessarily lead to loss-of-function, and b) multiple gene copies of a gene or paralogous genes could be targeted with a single construct. In our work, the gene coding the transcriptional activator of hemicellulases XlnR was silenced. Gene silencing resulted in various degrees of hemicellulase production depending on the different transformed fungal strains. In chapter 3, the effect of D-xylose on gene expression in A. niger was investigated. The inducer of (hemi)cellulases D-xylose was added to cultures of A. niger growing on the non-inducer sorbitol. Genes differentially expressed on D-xylose were identified as candidate genes involved in the response to this sugar. This study confirmed that D-xylose activates enzymes involved in xylan degradation and D-xylose utilisation, but also enzymes responsible for the removal of other monomers that occurr on arabinoxylan and cellulases. Statistical analysis of variance components was used to assess the contribution of each external factors affecting the measured gene expression. Such analysis of variance components is important for reproducible sample processing for microarray analysis. Chapter 4 describes the A. niger secretory pathway proteins that are involved in the production of (hemi)cellulases, via induction by D-xylose. For this, A. niger was grown under the same conditions as the ones described in chapter 3. After the isolation of microsomes, the corresponding proteins were analysed by shotgun proteomics. Induction by D-xylose was correlated with an increase in proteins related to protein secretion, namely small GTPases for vesicle transport and polarised growth. Most importantly, under induction by D-xylose, the complex for protein degradation 20S proteasome was associated with microsomes. These results indicate a novel mode of regulation in which the proteasome is recruited to secretory organelles upon the induction of extracellular enzymes. In chapter 5, the analysis of secretory proteins described in chapter 4 is now applied to a system in which D-maltose is an inducer of starch-degrading enzymes. This chapter also includes the study of the proteins secreted after D-maltose or D-xylose. After D-maltose addition, three starch-degrading enzymes were found more abundant and after D-xylose addition, several enzymes were more abundant and these enzymes were mostly related to arabinoxylan and cellulose degradation. The effects of D-maltose on the microsomal proteome are similar to the effects of D-xylose. Both the induction by D-maltose and by D-xylose resulted in increased amounts of mitochondrial proteins. Moreover, the 20S proteasome assembly is an ATP-dependent process. For this reason, it is hypothesised that the assembly and association of 20S proteasome upon induction is related to an increased ATP production in the vicinity of secretory organelles. <br/
Nederlandse vrouwen winnen vaker bij wielrennen, maar aandacht blijft achter
No full textstatus: Publishe
On the Rain-Wind Induced Vibrations of a Mass-Spring System
No full textIn this report, the rain-wind induced vibrations of cables are studied. This is done by modeling the cable cross-section as a mass-spring system with two time-varying masses. Thereafter, the solution of this model is approximated using a multiple timescale perturbation method. Lastly, for some choicesof the time-varying masses the eigenfrequencies are analyzed, stability properties are derived, and approximations of the solutions are given
Modular Smart Design of Tuber Washing Lines: A Novel Design Approach
No full textTummers Food Processing Solutions is an internationally operating company based in the Netherlands, that sells factory lines for processing tuberous products like potatoes. Before being processed into various products, the incoming tuber batches are always washed and cleaned from waste particles like clods, stones and haulm. For this purpose washing lines consisting out of different machines are used. Every processing application, customer and kind of input product results in different requirements regarding the machines, options and their configuration. Currently for every customer a tailor made machine line is designed, consisting out of customised machines based on the expertise of the corresponding sales agent and the engineer that designs the machines. This results in individually designed machines, friction between different departments and mistakes in drawings, parts lists, manufacturing, documentation and others. Once installed on site, the machine line is controlled by machine operators that keep the factory operational but are not optimising the performance and efficiency of the machine line nor conduct preventive maintenance. To tackle both the issues on the company and the customer side, the strategy for designing these tuber washing lines has to be turned into adaptive machine line design. Adaptive machine line design is a combination of modular design and smart factory engineering. Machine lines are customer specifically configured out of standardised modules and controlled by smart systems to optimize performance and efficiency and predict maintenance.Because potatoes are by far the most commonly processed product, followed up by carrots, this research focusses on potato washing lines with some specific side notes for processing carrots. Based on sales records and customer preferences, a set of standardised machine models and options is defined as the machine portfolio. This portfolio consists out of ten different machines, each available in different sizes, with waste and product streams to different directions and other standardised options. A jigsaw puzzle model can be made where this machine portfolio is build up as a set of puzzle pieces. For every different application a set of these puzzle pieces can be chosen from the portfolio and connected in different configurations. To determine which machines with which options to choose from the portfolio in which order, a model can be used. This model is based on a set of input- output relations and first set up as a decision scheme after which it is modeled in LabView as a basic machine line configurator. The model is then used to configure machine lines for five different examples. Each example is an existing order with differences in customer specific wishes, input and output characteristics and boundary conditions regarding factory layout and peripheral equipment. With help of these five examples the model is iteratively checked and improved after which the amount of customer specific engineering is determined that still needs to be performed after standardising of the machines. A first layer of a Digital Twin for smart control of the washing line is designed. This control strategy is based on the Key Performance Indicators of the washing line and their relations between them. Based on open or closed loop control, a set of control schemes is created for each machine that requires smart control.A thorough analysis of the costs and benefits of implementing a modular design strategy for the tuber washing lines shows that huge amounts of man hours can be saved after implementation. Next to these savings in labour, less mistakes will be made in the design and manufacturing of the machines which improves the professional image of the company and lowers friction between different departments and stress on the workfloor. Due to significant savings in replacing wear sensitive parts, reduced factory downtime, loss of product in waste streams and reduced operator wadges, installing a system for smart control can easily be earned back in the first year of operations. All and all changing the design strategy for tuber washing lines to adaptive machine line design is very promising for both the machine line manufacturer as for the customer.Mechanical Engineering | Multi-Machine Engineerin
Design of Criticality-Based Haptic Steering Guidance for Human Like Adaptation to Different Lane Keeping Tasks
No full textHaptic steering guidance is an advanced driving assistance system which provides guidance torques on the steering wheel to assist a human driver. Improvements in performance, safety margins and workload have been reported for lane-keeping and curve negotiation tasks. On the other hand, the guidance system instigates increased driver torques, indicating the occurrence of a mismatch between driver and automation intention. A novel, criticality-based control structure was developed, capable of adapting to different driving conditions by using safety margins (operationalized as time-to-line crossing, TLC) as input. Twenty-four participants drove through a single-lane, 10.8 km long road, with as independent variables the road width (normal road width of 3 m, wide road width of 5 m) and the type of guidance received: no guidance (manual), haptic steering guidance based on lateral deviation from the center-line (performance-based guidance, PBG) and criticality-based guidance (CBG). On the normal road, results show similar benefits for both guidance systems compared to manual control, in terms of performance and safety margins. Workload was reduced by PBG, but both guidance systems yielded increased driver torques. On the wide road, participants drove closer to the center-line with PBG, but at the cost of significantly more guidance torques than CBG. Interestingly, this reduction in lateral deviation did not result in a significant improvement for lowest safety margins encountered. No subjective preference was found for either feedback condition. It can be concluded that criticality-based guidance is capable of adjusting to different driving conditions, without compromising safety margins, whilst greatly reducing guidance torques in situations where they are unneeded.<br/
Feasibility study of a heat pump assisted flower bulb drying system: An opportunity to bring sustainable energy solutions to the agriculture sector
No full textIn some countries, drying processes use up to 20% of the total energy consumption. Within the agriculture sector, drying of food and flowering products is a necessary step in production. A lot of companies make use of hot air dryers where the heat is gained by burning natural gas. A novel method is to use a heat pump assisted drying systems instead. Heat pump assisted drying realises a better product quality due to the ability of humidity and climate control of the drying medium: air. Additionally, there are possibilities for energy savings up to 50%. This thesis project is mentioned as the first step for an initiative to introduce heat pump drying into the horticulture sector. The project started almost 1 year ago and is still far from finished. Main goal was to get a good understanding of the product drying behaviour, drying capacities and the system requirements and footprints. Conclusions should determine whether there is a possibil-ity for market implementation or not. The results in this report are promising. Heat pump drying is a trending research topic in science, where new developments on predicting the dynamic drying behaviour of agricultural products show up every month. This study involves a computational model, where the dynamic process of drying flower bulbs is simulated. This model is validated by measurements on existing drying in-stallations. Building this model resulted in a good understanding about the flower bulb characteris-tics and the necessary drying capacities. Additionally, Heat pump drying systems are evaluated and a dynamically modelled. When both models are the drying process of FB’s can be optimized. The first protype of the HP drying system that will be used in further research will be shortly discussed. Conclusion of this report is that heat pump drying is a promising technique for drying of FB’s. The combination of technical advantages with energy savings, could lead to better product quality and lower production costs. The business case is strengthened by future perspectives where energy efficiency and reduction of CO2 emissions will more and more important due to climate change.Mechanical Engineering | Process and Energy Technolog
Low-thrust horizontal Lyapunov orbits in the circular restricted three-body problem: A numerical exploration of the planar periodic solution structure within a combined low-thrust three-body dynamical model
No full textPreliminary design of low-thrust trajectories in the circular restricted three-body problem (CR3BP) frequently relies upon ballistic dynamical structures and optimization algorithms. A fundamental understanding of how these dynamical structures change due to presence of a low-thrust force may lead to trajectories that cannot be obtained otherwise. This paper investigates the effect of a constant low-thrust acceleration on the horizontal Lyapunov (H-L) families in the CR3BP. Families of low-thrust periodic solutions are constructed in vicinity of L1 and L2 using numerical continuation methods. By either varying the Hamiltonian, acceleration magnitude, or acceleration orientation along the solution family, the effect of a low-thrust acceleration on H-L orbits is characterized. Investigating the geometry, bifurcations and hyperbolic unwinding behavior of these families provides insight into the low-thrust periodic solution structure of the Earth-Moon system. The introduction of a constant low-thrust acceleration distorts the geometry of ballistic H-L orbits into ’ear-shaped’ periodic solutions. The bifurcations of the low-thrust periodic solution families imply the existence of low-thrust halo, low-thrust axial, and low-thrust planar double-period families. Finally, low-thrust periodic solutions are identified that possess a higher rate of hyperbolic unwinding behavior than the ballistic L1 and L2 H-L families.Aerospace Engineerin
Circular Economy Impact Analysis Model for Image Guided Therapy Devices
No full textThe healthcare sector contributes significantly to humanity’s environmental impact on our planet. The circular economy (CE) has been heralded as a solution addressing its economic and environmental challenges by promoting more efficient use of materials. Stakeholders throughout the entire industry need to adapt their business models towards more sustainable and cost effective circular alternatives. Examples of CE strategies are the utilization of subscription-based business models, de-materialization of product chains and the maximizing of physical assets’ useful life. For medical disposables, the CE transition is challenged by apparent limitations in economical, behavioural, and operational feasibility. This study involves the embedding of CE thinking into Philips image guided therapy devices (IGT-D) by incorporating the projected impact of circular adaptations into the decision-making process between project proposals. A model was developed to facilitate the appraisal and selection of CE opportunities within existing IGT-D products. It assesses their impacts to the business according to six categories: i) Marketing, ii) Resource investment, iii) Capital investment, iv) P&L (profit and loss), v) Dependency and vi) Legal & regulatory. This model calculates impact scores that reflect the efforts necessary to implement these proposals as well as their potential advantages. The usability and value of the model were assessed in a case series, which produced promising yet inconclusive results. Although the model demonstrated potential to fill in the knowledge gaps for implementation of circular proposals by assessing their impacts, its ability to assist the decision-making process between proposals is in need of further validation. Future research into CE adoption in IGT-D needs to determine its impacts based on real outcomes and may be used to validate the model’s projections.Biomedical Engineering | Medical Instruments and Medical Safety (MIMS
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