A model for uphill droplet motion

This paper was presented at the 4th Micro and Nano Flows Conference (MNF2014), which was held at University College, London, UK. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute, ASME Press, LCN London Centre for Nanotechnology, UCL University College London, UCL Engineering, the International NanoScience Community, www.nanopaprika.eu.This paper focuses on the behaviour of a liquid droplet over the surface of a treated solid substrate. It deals with the use of surface tension forces induced by setting up a gradient of wettability to allow the evacuation of the dispersed phase. The main aim is to present a new model capable of predicting the motion of a droplet of known volume over a surface with a wettability gradient that explicitly takes contact angle hysteresis into account. Several authors have established a phenomenological footprint radius, from which the droplet starts moving. Our model, provides a relationship to find this critical droplet size. The results show that the contact angle hysteresis parameter appears to be a key issue in droplet dynamics and in the accurate prediction of droplet motion

IsoEx: an explainable unsupervised approach to process event logs cyber investigation

39 seconds. That is the timelapse between two consecutive cyber attacks as of 2023. Meaning that by the time you are done reading this abstract, about 1 or 2 additional cyber attacks would have occurred somewhere in the world. In this context of highly increased frequency of cyber threats, Security Operation Centers (SOC) and Computer Emergency Response Teams (CERT) can be overwhelmed. In order to relieve the cybersecurity teams in their investigative effort and help them focus on more added-value tasks, machine learning approaches and methods started to emerge. This paper introduces a novel method, IsoEx, for detecting anomalous and potentially problematic command lines during the investigation of contaminated devices. IsoEx is built around a set of features that leverages the log structure of the command line, as well as its parent/child relationship, to achieve a greater accuracy than traditional methods. To detect anomalies, IsoEx resorts to an unsupervised anomaly detection technique that is both highly sensitive and lightweight. A key contribution of the paper is its emphasis on interpretability, achieved through the features themselves and the application of eXplainable Artificial Intelligence (XAI) techniques and visualizations. This is critical to ensure the adoption of the method by SOC and CERT teams, as the paper argues that the current literature on machine learning for log investigation has not adequately addressed the issue of explainability. This method was proven efficient in a real-life environment as it was built to support a company\'s SOC and CER

Experimental Study of Slug Flow for Condensation in a Square Cross-Section Micro-Channel at Low Mass Velocities

This paper was presented at the 4th Micro and Nano Flows Conference (MNF2014), which was held at University College, London, UK. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute, ASME Press, LCN London Centre for Nanotechnology, UCL University College London, UCL Engineering, the International NanoScience Community, www.nanopaprika.eu.In this paper, condensation flows in a cross-flow air-cooled micro-condenser were investigated for mass velocities (representing the mass flow rates over the micro-condenser cross-section area) lower than 12 kg.m (−2).s(−1), with n-pentane used as the working fluid. This micro-condenser consisted of a transparent square cross-section micro-channel placed horizontally, having inner and outer edges of 553 and 675 μm, respectively, and a real length exposed to the coolant of 196 mm. One of the specificities of the experimental bench was the choice of the air as a coolant so that the external heat transfer is limiting. Three main flow zones were identified: annular zone, intermittent (i.e. elongated bubbles or slug) zone and spherical bubbles zone. A specific experimental procedure based on bubbles tracking was developed in order to determine the hydraulic and thermal parameters in the intermittent zone. The mean displacement and condensation velocities of the elongated bubbles were determined according to their mean length for different mass velocities of the n-pentane. Besides, the mean latent heat flux density released by the condensation of the elongated bubbles was determined according to their mean surface for different mass velocities of the n-pentane, and compared to the imposed heat flux density

On the effect of the dynamic contact angle of a vapor embryo interface trapped in a nucleation site

This paper was presented at the 4th Micro and Nano Flows Conference (MNF2014), which was held at University College, London, UK. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute, ASME Press, LCN London Centre for Nanotechnology, UCL University College London, UCL Engineering, the International NanoScience Community, www.nanopaprika.eu.The effect of boiling and cavitation phenomena on nucleation was first experimentally studied. Results highlight the fact that the "classical" theory of nucleation cannot describe such a configuration. New theoretical approaches were proposed in order to describe the dynamic effects which occur when the liquid pressure oscillates over time and when a heat flux imposed to the system. It then appears that the dynamic and the hysteresis of the contact angle may play a significant role in nucleation by simultaneous boiling and cavitation effects

Control of pool boiling incipience in confined space: dynamic morphing of the wall effect

This paper was presented at the 3rd Micro and Nano Flows Conference (MNF2011), which was held at the Makedonia Palace Hotel, Thessaloniki in Greece. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, Aristotle University of Thessaloniki, University of Thessaly, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute.A new active heat transfer enhancement and control technique is proposed in this work. One of the major aims of the technique is to decrease pool boiling incipience temperature by dynamic morphing imposed to confinement wall. Dynamic deformation generates variation of pressure which increases the fluid metastability level. An experimental device was built to evaluate boiling incipience temperature. Experimental results were compared with hydrodynamic and nucleation models.CNRS Energie CITAMPE PR09-3.1.3-2 and FNRAE SYRTIP

Flow patterns and heat transfer in a square cross-section micro condenser working at low mass fluxes

This paper was presented at the 3rd Micro and Nano Flows Conference (MNF2011), which was held at the Makedonia Palace Hotel, Thessaloniki in Greece. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, Aristotle University of Thessaloniki, University of Thessaly, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute.Flow patterns and heat transfer in an air-cooled square cross-section micro condenser were investigated. The test section consisted of a borosilicate square micro channel, of inner and outer hydraulic diameters of 0.49 mm and 0.6 mm respectively, and a length of 100 mm. The transparent material of the micro channel allowed the visualization of the different condensation flow patterns. The imposed mass velocities were ranging between 1 and 10 kg m-2 s-1. In this range of mass fluxes, three main flow regimes were identified: Annular regime, intermittent regime, and spherical bubbles regime. Then, the isolated bubbles zone (the end of the intermittent zone + the spherical bubbles zone) was particularly studied. A specific experimental procedure was developed, basing on bubble tracking, in order to determine accurately the hydraulic and thermal parameters profiles in this zone according to the axial position in the micro channel, such as the vapour quality profile x(z). Thanks to energy balance, the liquid temperature profile Tl(z) in the isolated bubbles zone was determined for different initial values. A thermal non-equilibrium between the liquid and vapour phases was identified. Therefore, the latent heat flux was then quantified and compared to the total heat flux in this zone.FNRAE (MATRAS) and the Microgravity Application Program of the European Space Agenc

Phototransformation d'herbicides tricétoniques et d'insecticides pyréthrinoïdes à la surface des végétaux

When crops are sprayed with pesticides, the leaves are covered with fine droplets containing the active ingredient. Pesticides can then be broken down by sunlight. We showed in this work that mesotrione and sulcotrione herbicides as well as cypermethrine and deltamethrine insecticides are photolabile when sorbed on cuticular waxes. The pesticide photolysis rate can both increase or decrease, if additives from commercial fomulations are added. However, we could not find a general rule that could predict the importance of the phototransformation for any pesticide. Moreover, while phototransformation was the only dissipation process during experiments in the laboratory, other dissipation processes, such as diffusion through the plant cuticle or wash off by rain or dew, can compete and even become predominant in field studies.Les pesticides appliqués par pulvérisation dans les cultures sont dispersés à la surface des plantes où ils peuvent être transformés sous l'effet de la lumière solaire. Nous avons montré dans ce travail que les herbicides mésotrione et sulcotrione, et les insecticides cypermétrine et deltaméthrine sorbés à la surface des cires cuticulaires, sont photosensibles. Cette propriété est modifiée par l'ajout d'additifs présent dans les formulation commerciales ? Ces derniers peuvent accélèrer ou ralentir la photolyse des principes actifs. Cependant, il ne semble pas y avoir de règle générale permettant de prévoir l'importance de la phototransformation pour chaque matière active. D'autre part, alors qu'en laboratoire la dissipation des pesticides étudiés est uniquement due à la phototranformation ; sur les plantes entières, d'autres phénomènes interviennent. La diffusion dans la cuticule et les pertes dues au lessivage par la pluie ou la rosée peuvent devenir prépondérantes devant la phototransformation

Accidental Removal of a Carotid Endovascular Stent during Oropharyngeal Mass Biopsy

A 54-year-old male patient, with a history of a right mandibular adenocarcinoma, previously excised, and treated with post operative chemo- and radio-therapy, presented with a right oropharyngeal necrotic mass of several months duration. His history is pertinent for a right internal carotid endovascular stenting 2 years prior to presentation. During biopsy of his oropharyngeal lesion, a specimen of tissue was retrieved, with the carotid stent within. There was no bleeding. To the best of our knowledge, there is no such case reported in the literature. We present this case as a reminder on the importance and risks of radiation-induced necrosis and its distortion of the surrounding anatomy, especially in the presence of foreign bodies or protheses

Signs of spatial neglect in unilateral peripheral vestibulopathy

Background and purpose In this study, the question of whether egocentric representation of space is impaired in chronic unilateral vestibulopathies was examined. The objective was to test current theories attributing a predominant role to vestibular afferents in spatial cognition and to assess whether representational neglect signs are common in peripheral vestibular loss. Methods The subjective straight-ahead (SSA) direction was investigated using a horizontal rod allowing the translation and rotation components of the body midline representation to be dissociated in 21 patients with unilateral vestibular loss (right, 13; left, eight) and in 12 healthy controls. Results Compared to the controls, the patients with unilateral vestibulopathy showed a translation bias of their SSA, without rotation bias. The translation bias was not lateralized towards the lesioned side as typically found for biases reported after unilateral vestibular loss. Rather, the SSA bias was rightward whatever the side of the vestibular loss. The translation bias correlated with the vestibular loss, as measured by caloric response and vestibulo-ocular reflex gain, but not with the subjective visual vertical or the residual spontaneous nystagmus. Conclusion The present data suggest that the dysfunctions of neural networks involved in egocentred and allocentred representations of space are differentially compensated for in unilateral vestibular defective patients. In particular, they suggest that asymmetrical vestibular inputs to cortical regions lead to representational spatial disturbances as does defective cortical processing of vestibular inputs in spatial neglect after right hemisphere stroke. They also highlight the predominant role of symmetrical and unaltered vestibular inputs in spatial cognition