141 research outputs found

    Profit-driven planning and analysis of a WEEE recycling facility with a multi-period MILP model

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    Electronic waste is one of the fastest-growing waste streams in the world. The challenges associated with the recycling of Waste Electrical and Electronic Equipment (WEEE) represent both threats, as the improper disposal of this waste can harm the environment and human health, and opportunities, as this category of waste contains valuable and rare resources that can be recovered and repurposed, contributing to the circular economy. The EU is leading the way in improving the collection and treatment of WEEE, but this has not been sufficient to meet the targets set in its WEEE directive. Therefore, additional efforts must be made to ensure the costeffective and environmentally sound recycling of WEEE, both in the public and private sectors. In this thesis, we propose a multi-period MILP model for the planning of a WEEE recycling facility in Belgium and conduct various analyses to provide insights on what elements are the most crucial to the profitability of such a facility. The originality of our approach lies in the multi-period aspect of the model, and the addition of a limited amount of labour to be allocated to various labour-intensive tasks of WEEE recycling. Our main findings are that labour is the most critical resource, both in cost and utilization, such that the optimal quantity of WEEE to process is the one that results in complete utilization of labour, with little to no overtime. As such, the flexibility of labour, both in possible task allocation and overtime capabilities, is crucial to the proper functioning of the facility, especially when taking into account possible deviations from the optimal plan, caused by the heterogeneity of WEEE and other variations such as the timing of deliveries.nhhma

    Proefsleuvenonderzoek Boom: Molenstraat-Kruisstraat -Esperantostraat

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    Dit rapport werd ingediend bij het agentschap samen met een aantal afzonderlijke digitale bijlagen. Een aantal van deze bijlagen zijn niet inbegrepen in dit pdf document en zijn niet online beschikbaar. Sommige bijlagen (grondplannen, fotos, spoorbeschrijvingen, enz.) kunnen van belang zijn voor een betere lezing en interpretatie van dit rapport. Indien u deze bijlagen wenst te raadplegen kan u daarvoor contact opnemen met: [email protected]

    Miniaturized Thin-Film Piezoelectric Traveling Wave Ultrasonic Motor

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    For many small-scale systems, compact rotary actuators are highly attractive. Many current millimeter-scale motor technologies, such as electrostatic motors and electromagnetic motors, operate at high speeds (on the order of 105 RPM) but low torque, usually pico- or nano-newton-meters. In order to drive large loads at speeds closer to 100 to 1000 RPM, gearing would be required, which drastically increases system complexity and size. Electromagnetic motors, which are effective at the macro-scale, become less practical at the millimeter-scale due to unfavorable scaling of energy density and complex fabrication. Electrostatic micro-motors require approximately 100 V for operation and produce limited torque. Traveling wave ultrasonic motors (TWUM) can provide micro- to milli-newton-meters of torque at low speeds and fill a necessary place within the millimeter-scale rotary motor landscape. Using recent developments in high quality piezoelectric film deposition and microfabrication techniques, TWUM can be made an order of magnitude smaller than currently possible. The fabrication process for the TWUM is described within, with a focus on stator fabrication and the enabling fabrication methods developed for the manufacture of TWUM, including backside vapor-HF release, deep reactive ion etch footing release, and photoresist deep-trench refill. Design and characterization of the traveling wave stator component, both disc and ring are described. Disc stators, 1 to 3 mm in diameter, exhibited traveling waves up to 1 μm in out-of-plane amplitude with quality factors in air of 95. The design process for ring stators with mechanical impedance transformer tethers is presented. The tethers are designed to allow large motion at the stator perimeter, while tethering the stator to the anchored substrate. This mechanical impedance transformer tether allowed for an in increase in standing wave amplitude by over 100% compared to straight tethers. TWUM were demonstrated and characterized, and represent the smallest TWUM currently reported, at 2 to 3 mm in diameter and less than 1 mm thick. Motor performance characteristics are presented, with speeds exceeding 2000 RPM while consuming 4 mW of power at 10 V. These millimeter-scale motors have potential applications in fields such as fuzing, medical imaging, micro-robotics, and sensor steering and calibration

    Combinatorial and Automated Proofs of Certain Identities

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    This paper focuses on two binomial identities. The proofs illustrate the power and elegance in enumerative/algebraic combinatorial arguments, modern machine-assisted techniques of Wilf-Zeilberger and the classical tools of generatingfunctionology.United States. National Security Agency (Grant H98230-10-1-0222

    EEG Frequency Tagging Reveals the Integration of Form and Motion Cues into the Perception of Group Movement

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    The human brain has dedicated mechanisms for processing other people's movements. Previous research has revealed how these mechanisms contribute to perceiving the movements of individuals but has left open how we perceive groups of people moving together. Across three experiments, we test whether movement perception depends on the spatiotemporal relationships among the movements of multiple agents. In Experiment 1, we combine EEG frequency tagging with apparent human motion and show that posture and movement perception can be dissociated at harmonically related frequencies of stimulus presentation. We then show that movement but not posture processing is enhanced when observing multiple agents move in synchrony. Movement processing was strongest for fluently moving synchronous groups (Experiment 2) and was perturbed by inversion (Experiment 3). Our findings suggest that processing group movement relies on binding body postures into movements and individual movements into groups. Enhanced perceptual processing of movement synchrony may form the basis for higher order social phenomena such as group alignment and its social consequences

    The associative aspects of memory for words and faces in patients with pre-dementia Alzheimer's disease

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    This work was aimed at exploring the associative aspects of memory for words and faces in patients with pre-dementia Alzheimer’s disease (preAD), in order to better understand the processes underpinning their episodic memory deficit. Our studies led to the formulation of different hypotheses with this respect and the proposition of a model integrating the two conceptual frameworks on which we based our work. Based on this model, we suggested that the episodic memory deficit in preAD may originate from impaired pattern separation processes implementing distinct contextual representations, which probably combines with impaired item-context binding processes. Accordingly with previous findings, our work highlighted that preAD patients may also present other deficits than episodic memory deficit. Together, these results support the idea that the memory and cognitive deficits in preAD are underpinned by a constellation of impaired processes, which still need to be further investigated.(BIFA - Sciences biomédicales et pharmaceutiques) -- UCL, 201
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