A Bio-inspired HTTP-based adaptive streaming player

In order to streamline video content distribution on a myriad of platforms over heterogeneous networks, HTTP Adaptive Streaming (HAS) has been increasingly adopted. In this paper we pilot a bio-inspired HAS optimisation design with the aim to maximise the overall use experiences of a video playback session. Evaluations conducted within a real-world Internet environment demonstrate the benefit of our design using quality indicators such as convergence time, start-up delay, average video rate, stability, and fairness

A survey of self organisation in future cellular networks

This article surveys the literature over the period of the last decade on the emerging field of self organisation as applied to wireless cellular communication networks. Self organisation has been extensively studied and applied in adhoc networks, wireless sensor networks and autonomic computer networks; however in the context of wireless cellular networks, this is the first attempt to put in perspective the various efforts in form of a tutorial/survey. We provide a comprehensive survey of the existing literature, projects and standards in self organising cellular networks. Additionally, we also aim to present a clear understanding of this active research area, identifying a clear taxonomy and guidelines for design of self organising mechanisms. We compare strength and weakness of existing solutions and highlight the key research areas for further development. This paper serves as a guide and a starting point for anyone willing to delve into research on self organisation in wireless cellular communication networks

07171 Abstracts Collection -- Visual Computing -- Convergence of Computer Graphics and Computer Vision

From 22.04. to 27.04.2007, the Dagstuhl Seminar 07171 ``Visual Computing - Convergence of Computer Graphics and Computer Vision\u27\u27 was held in the International Conference and Research Center (IBFI), Schloss Dagstuhl. During the seminar, several participants presented their current research, and ongoing work and open problems were discussed. Abstracts of the presentations given during the seminar as well as abstracts of seminar results and ideas are put together in this paper. The first section describes the seminar topics and goals in general. Links to extended abstracts or full papers are provided, if available

1st year EFAST annual report

The present report provides information about the activities conducted during the 1st year of the EFAST project. The first chapter is dedicated to describe the inquiries conducted at the beginning of the project and to briefly summarise the main results. The second chapter is dedicated to the first EFAST workshop where some of the leading scientists in the field of earthquake engineering have met to discuss about the need and the technologies related to earthquake engineering. The third chapter contains a state of the art and future direction in seismic testing and simulation. The final chapter is dedicated to describe the preliminary design of the web portal of the future testing facility.JRC.DG.G.5-European laboratory for structural assessmen

Development and application of synchronized wide-area power grid measurement

Phasor measurement units (PMUs) provide an innovative technology for real-time monitoring of the operational state of entire power systems and significantly improve power grid dynamic observability. This dissertation focuses on development and application of synchronized power grid measurements. The contributions of this dissertation are as followed:First, a novel method for successive approximation register analog to digital converter control in PMUs is developed to compensate for the sampling time error caused by the division remainder between the desirable sampling rate and the oscillator frequency. A variable sampling interval control method is presented by interlacing two integers under a proposed criterion. The frequency of the onboard oscillator is monitored in using the PPS from GPS.Second, the prevalence of GPS signal loss (GSL) on PMUs is first investigated using real PMU data. The correlation between GSL and time, spatial location, solar activity are explored via comprehensive statistical analysis. Furthermore, the impact of GSL on phasor measurement accuracy has been studied via experiments. Several potential solutions to mitigate the impact of GSL on PMUs are discussed and compared.Third, PMU integrated the novel sensors are presented. First, two innovative designs for non-contact PMUs presented. Compared with conventional synchrophasors, non-contact PMUs are more flexible and have lower costs. Moreover, to address nonlinear issues in conventional CT and PT, an optical sensor is used for signal acquisition in PMU. This is the first time the utilization of an optical sensor in PMUs has ever been reported.Fourth, the development of power grid phasor measurement function on an Android based mobile device is developed. The proposed device has the advantages of flexibility, easy installation, lower cost, data visualization and built-in communication channels, compared with conventional PMUs.Fifth, an identification method combining a wavelet-based signature extraction and artificial neural network based machine learning, is presented to identify the location of unsourced measurements. Experiments at multiple geographic scales are performed to validate the effectiveness of the proposed method using ambient frequency measurements. Identification accuracy is presented and the factors that affect identification performance are discussed

Experimental investigations of the fluid dynamics of vitreoretinal surgery

Vitrectomy is a surgical procedure by which the vitreous humour is removed from the vitreous chamber of the eye and is replaced with a tamponade fluid. Vitrectomy is performed by means of a system consisting of several components, including the vitreous cutter, which aspirates the vitreous body, a viscoelastic fluid that occupies the vitreous chamber of the eye. The vitreous cutter port geometry may have great influence in vitrectomy surgery from the fluidics and safety standpoints. For this reason, there has been an increase interest from ophthalmic companies in optimising the fluidics within the vitreous chamber during surgical maneuvers, in order to avoid retinal tractions and intraocular pressure (IOP) variations. Once removed, the vitreous is often replaced with Silicone Oils (SOs), which, however, inevitably tend to emulsify in the aqueous solution present in the eye, limiting the chances of using SOs as long term vitreous substitutes. Many months are indeed often required for complete healing of retinal damages. Moreover, formation of emulsions triggers local inflammatory processes, which can cause further complications. This thesis is an experimental work related to the physics of ocular surgical procedures and it consists of two main parts. The first part concerns the fluid mechanics of the vitrectomy procedure. In particular, experiments with different approaches have been performed on the fluidics of various vitrectomy systems, with the objective of identifying ideal working conditions that minimise the risks of retinal damages, while keeping the surgical procedure efficient. The second part is related to the characterisation of the interfacial rheology between SOs and aqueous solutions containing endogenous proteins released by the ocular tissue as a response to an inflammatory state. Aim of this part is to investigate to what extent biomolecules present in the aqueous solution can modify the rheological properties of the interface between the two fluids and, in turn, facilitate the formation of an emulsion. This work is carried out in collaboration with Dr. Libero Liggieri at CNR-ICMATE. Each part consists of several chapters, which address various projects within these two topics and are briefly summarised below. PART I. PERFORMANCE ASSESSMENT OF VITRECTOMY DEVICES An important issue associated with vitrectomy is the risk of generation of retinal tractions by the vitreous cutter. It has been demonstrated that an intermittent flow generates fluid accelerations, with consequent pressure variations within the vitreous chamber, which may result in pulsatile tractions on the retina, with significant risk of iatrogenic retinal damage. Rossi et al. (2014b) proposed a conceptual diagram according to which, for a safe and efficient vitrectomy, optimisation of fluidics can be achieved by maximising the flow rate and minimising the acceleration around the cutter port. Another important aspect of the surgical procedure is prevention of large IOP changes within the eye. In particular, ocular hypertension or ocular hypotony can have very important clinical consequences. In order to maintain a normal IOP value, the balance between the aspiration and the irrigation pressures during vitrectomy plays a very important role. In chapter 1 we reviewed the literature concerning fluid dynamics of vitreoretinal surgery. In chapter 2 we evaluated the performance of vitreous cutters in vitro in terms of flow rate, using vitreous phantoms with different rheological properties (artificial vitreous, AV). On each fluid solution we performed rheological tests in order to obtain a good control of the properties of the working fluid and thus guarantee reproducibility of the experiments. This allowed us to compare the efficiency of the instruments in a highly controlled environment and to assess how their behavior is affected by fluid properties. Our results showed that all cutters are higly sensitive to fluid rheology and this is particularly true for double blade cutters, which, however, always produce larger flow rates compared to single blade ones. These findings imply that large flow rate fluctuations should be expected when a vitreous cutter is operated in a medium with heterogeneous mechanical properties (Nepita et al., 2021). In chapters 3 and 4 we show two experimental studies aimed at assessing the performance of two vitrectomy systems, characterised by different technologies (guillotine and ultrasound probes), tested both with balanced salt solution (BSS) and AVs. The following types of experiments have been performed in a cubic testing chamber. - Flow rate measurements: mean flow rate has been measured using a digital image tracking process for all cutters, changing the operational parameters within a wide range (cutting frequency, aspiration pressure, etc.). Results for guillotine cutters show that for viscoelastic fluids the averaged flow rate only slightly decreases as the cutting frequency increases. The ultrasound cutters produce larger flows regardless the stroke (the amplitude of the ultrasound vibrations of the needle). - Flow fields measurements: two dimensional PIV experiments have been performed with the goal of characterising the flow fields generated by all cutters. For each set of parameters, a sequence of images has been acquired on two different planes: \u201cfrontal view\u201d and \u201clateral view\u201d. Moreover, for a specific solution, two areas of interest have been used for the acquisition: a \u201clarge field\u201d of view, aimed at describing the entire circulation induced by the cutters at the scale of the experimental box, and a \u201csmall field\u201d of view, i.e. a zoom around the cutter tip, to describe more accurately flow structures around the cutter port. The flow induced by ultrasound cutters is strongly three dimensional and time dependent. Flow structures are generated at different spatial scales, from large scales similar to the experimental domain to smaller scales close to the cutter port (Stocchino et al., 2020). - Temperature measurements: a specific task was dedicated to measure temperature variations induced by ultrasound cutters as a function of the stroke, maintaining the vacuum pressure equal to zero. The two dimensional variation of the temperature field has been monitored with an infrared thermal camera. The acquired thermal images were used to obtain the temperature variations in time at a particular spot, or to generate two dimensional temperature maps. The temperature slightly grows but this effect is likely to be clinically irrelevant, since infusion of a different fluid will mitigate it. Moreover, the cutter head reaches maximum values close to body temperature, meaning that it will not transmit much heat to the needle and eventually to the vitreous during surgery (Stocchino et al., 2020). - Pressure measurements: for this specific type of experiments a model of the human vitreous chamber at real scale and with a realistic geometry has been employed. The eye model has been designed considering both infusion and aspirations lines, thus mimicking the real surgical procedure. The main goal of this part of the research activity is to perform pressure measurements at two different positions of the vitreous chamber (anterior and posterior): for this purpose two high precision pressure transducers (Viatran model 422) have been used. Results show that dynamic variations of the pressure due to the motion of the cutter blade are always small compared to the average pressure in the eye. Pressure fluctuations related to fluid motion are felt more intensely by the pressure sensor placed on the back of the vitreous chamber, opposite with respect to the irrigation line. This is probably due to the generation of a jet that impinges the chamber wall opposite to its position. When the aspiration phase begins the pressure in the eye model drops, which is related to hydraulic head (pressure) losses along the pipelines of the system. This pressure drop is typically reduced (sometimes very efficiently) when the vitrectomy system can actively compensate pressure variations. Results suggest that maximum irrigation pressure that can be used for compensating pressure losses during aspiration should be selected depending on several parameters such as the minimum irrigation pressure and the aspiration pressure, in order to optimise the desired compensation. PART II. STUDY OF SILICONE OIL EMULSIFICATION IN RELATION TO VITRECTOMY The tendency of SOs to emulsify in water is influenced by the chemico-physical properties of the fluids and interface and by external factors, such as temperature and mechanical energy provided to the system. Exposition of the SO to endogenous molecules (proteins, lipids, etc.) in the vitreous chamber, the presence of which is favored by the post-surgical inflammatory state of ocular tissues, is also considered to be important for the generation of an emulsion. The mechanisms at the basis of the effects of these molecules on the emulsification process depend on their capability to adsorb at the water-oil interface, modifying the mechanical interfacial properties, such as the interfacial tension (IT) and the dilational viscoelasticity (DV), i.e interfacial rheological response to surface variations. In chapters 5 and 6 we give an overview of the possible mechanisms for SO emulsion formation and stabilisation, with a particular focus on biomolecules adsorption processes at the SO-aqueous interface. In chapter 7 we propose an experimental study aimed at achieving a chemico-physical characterisation of the interfacial properties between SOs and aqueous solutions and at investigating the effect of surfactant biomolecules, such as albumin and \u3b3-globulins, possibly responsible for emulsion formation. In particular, measurements of IT on pendant drops of the protein aqueous solution in the SO have been performed. These measurements have been carried out by a Drop Shape Tensiometer (PAT1-Sinterface, Berlin). This technique allows one to quantify the DV by measuring the IT response to small sinusoidal perturbations of frequency imposed on the interfacial area. Results show that adsorption of these proteins at the interface reduces the IT to values compatible with the generation of an emulsion and provides values of the DV compatible with a good stability of the resulting emulsions (Nepita et al., 2020). This study allowed us to understand the effect of individual, key blood proteins on the mechanical properties of the interface. In order to evaluate the overall effect of the presence of these proteins, we conducted a second series of experiments adopting whole human serum blood (WHSB) samples obtained from donors. The results obtained with the serum dissolved in the solution showed that, already in concentrations of 1-2 orders of magnitude smaller than that of single proteins, the IT significantly decreases, up to values compatible with the formation of an emulsion, indicating therefore possible synergistic effects with other components of the serum, in addition to the proteins previously studied. Moreover, the DV modulus increases up to rather high values, compatible with the stabilisation of the emulsions against the coalescence. Drugs used as intraoperative tools in vitrectomy can also act as surfactants. An example is the intraocular injection of an anti-inflammatory steroid, composed of micro crystal particles. To assess whether the drug has a surfactant role at the interface, we conducted a first series of experiments to quantify the IT and the DV properties. We performed the measurements on the aqueous phase of the dispersion (supernatant), which separates after the sedimentation of crystals. The experiments with the supernatant neither show a significant decrease of IT that can be associated with the formation of an emulsion, nor lead to significant DV values. However, it is known that dispersions of partially hydrophobic solid particles can give rise to particularly stable emulsions, known as Pickering emulsions (Binks, 2002). In order to verify the capability of biomolecules to form emulsions stable over the timescale of months, comparative emulsification tests have been performed and shown in chapter 8. Emulsions were produced using to the Double Syringe method (Gaillard et al., 2017). Although this emulsification method may be very different from what occurs in practice, it is significant for investigating the stability of the emulsion formed and is, therefore, used as a simple screening test. For all samples containing blood proteins or the steroid drug, the presence of an emulsion layer was detected, the thickness of which decreases with increasing dilution, and which was stable over long times. On the contrary, the sample containing the Dulbecco buffer alone was already separated a few minutes after the emulsion formation. Thus, we can conclude that blood proteins are able to form and stabilise emulsions. Moreover, the steroid drug is able to stabilise Pickering-type emulsions. Eye movements are the main source of mechanical energy applied to the interface between SO and aqueous solution inside the eye. A set of measurements in a realistic domain have been performed. A qualitative and a quantitative analysis of the risults are reported in chapter 9 and 10, respectively. In particular we have used a Plexiglass model of a vitreous chamber with realistic geometry. The experimental setup is equipped with an optical diagnostics for monitoring the emulsion, a mechanical system controlled by a computer to simulate eye saccadic movements and thermalised at 35\ub1C. Once filled with SO and aqueous solution, the model is mounted on a support connected to a computer-controlled motor. In this study, harmonic rotations were considered. The temporal evolution of the emulsion has been studied through acquisition of images with a digital camera. In the case of emulsions characterised by very small droplets, a microscope (Leica Microsystems, Switzerland) has been used to determine their distribution and size. The main result obtained from these experiments consists in the formation and persistence of emulsions even when a low concentration of albumin has been dissolved in the aqueous solution (1% of the physiological concentration in blood). Moreover, the majority of the drops had a very small diameter: in the range of 0 \u2013 10 \u3bcm. Droplets with these characteristic dimensions are considered more dangerous from the clinical point of view, since they are able to favor the onset of ocular complications

Final report on the evaluation of RRM/CRRM algorithms

Deliverable public del projecte EVERESTThis deliverable provides a definition and a complete evaluation of the RRM/CRRM algorithms selected in D11 and D15, and evolved and refined on an iterative process. The evaluation will be carried out by means of simulations using the simulators provided at D07, and D14.Preprin

Cost-effective solution to synchronised audio-visual data capture using multiple sensors

Applications such as surveillance and human behaviour analysis require high- bandwidth recording from multiple cameras, as well as from other sensors. In turn, sensor fusion has increased the required accuracy of synchronisation be- tween sensors. Using commercial off-the-shelf components may compromise quality and accuracy, because it is difficult to handle the combined data rate from multiple sensors, the offset and rate discrepancies between independent hardware clocks, the absence of trigger inputs or -outputs in the hardware, as well as the different methods for timestamping the recorded data. To achieve accurate synchronisation, we centralise the synchronisation task by recording all trigger- or timestamp signals with a multi-channel audio interface. For sensors that don’t have an external trigger signal, we let the computer that captures the sensor data periodically generate timestamp signals from its se- rial port output. These signals can also be used as a common time base to synchronise multiple asynchronous audio interfaces. Furthermore, we show that a consumer PC can currently capture 8-bit video data with 1024x1024 spatial- and 59.1Hz temporal resolution, from at least 14 cameras, together with 8 channels of 24-bit audio at 96kHz. We thus improve the quality/cost ratio of multi-sensor systems data capture systems