642 research outputs found
Acoustic sensing of renal stone fragmentation in extracorporeal shockwave lithotripsy
No full textThis thesis describes the research carried out by the author on the exploitation of acoustic emissions
detected during extracorporeal shockwave lithotripsy (a non-invasive procedure for the treatment of
urinary stones) to develop a new diagnostic system. The work formed part of a research project on
lithotripsy undertaken by the University of Southampton in collaboration with Guy's and St Thomas'
NHS Foundation Trust (London) and a UK based company, Precision Acoustics Ltd (Dorchester). It
takes to a clinical conclusion the proposition made by Leighton and Coleman in 1992 that it might be
possible to build a sensor which would automatically exploit these passive acoustic emissions to
monitor the efficacy of a lithotripsy treatment. The work, predominantly experimental, involved both
in vitro and in vivo investigations. In particular, a first prototype diagnostic system (i.e. sensor plus
analysis software) was developed and tested in vitro during trials which included the use of a novel
cavitation sensor (on loan from the National Physical Laboratory, Teddington) and stone phantoms
designed by the author. This initial system was, then, refined and tested during clinical trials that
involved 130 patients. A preliminary trial on 51 patients aimed at refining the system and gathering
knowledge on the features of emissions recorded in vivo to produce an on-line monitoring system.
This trial was followed by other two trials that compared the output of the on-line acoustic system
against the ‘gold standard’ X-Ray assessment of treatments outcomes. The former of these two trials
involved 30 patients, and empirically defined the values of the key parameters (identified during the
in vitro tests) that would be used as the basis of the diagnosis. In particular, a classification rule of
treatments as being successful or unsuccessful was identified, and shown to agree significantly
(kappa=0.95) with the ‘gold standard’ follow-up assessment. The latter trial tested the final system
on 49 patients and confirmed an accurate treatment classification (kappa=0.94) in terms of the
successful/unsuccessful criterion
Vapor Pressure of Hydrofluoroolefins: Critical Review of Experimental Data and Models
No full textThis paper critically reviews vapor pressure data and vapor pressure models for seventeen hydrofluoroolefins, including R1234yf and R1234ze(E), and presents Wagner-type vapor pressure correlations for the seventeen hydrofluoroolefins
Quantum finite W-algebras for gl_N
No full textA major contribution to the theory of quantum finite W-algebras in type A comes from the work of J. Brundan and A. Kleshchev who, investigating the relationship between W-algebras and Yangians, achieved important results concerning both their structure and their representation theory.
In this framework, for a quantum finite W-algebra in type A, associated to any nilpotent element and arbitrary good grading, A. De Sole, V. Kac and D. Valeri constructed a matrix of Yangian type L(z) which encodes its generators and relations, generalizing the results of the same authors for classical affine W-algebras. We can then express L(z) in a nicer form: when the good grading is associated to a pyramid that is aligned to the right or to the left, we use a recursive formula to explicitly construct a matrix W(z) which provides us with a finite set of generators for the W-algebra satisfying Premet's conditions, and prove that the matrix L(z) can be obtained as a generalized quasideterminant of W(z). Finally, we explain how to generalize these results to an arbitrary good grading (and an arbitrary choice of an isotropic subspace), using fundamental results about the structure of quantum finite W-algebras due to W.L. Gan and V. Ginzburg, and J. Brundan and S. Goodwin
A Technological Update on Heat Pumps for Industrial Applications
No full textIt is now widely confirmed by scientific evidence that greenhouse gas emissions must be reduced to counteract the effects of global warming. The production of heat for industrial purposes is responsible for 36.8% of world energy-related emissions due to the widespread use of fossil fuels. Heat pumps are a key technology in the transition towards more sustainable industrial processes. In this paper, a systematic review of the literature produced in the last 5 years in international journals regarding the integration of heat pumps in industrial processes is presented. Firstly, papers presenting innovative configurations for high temperature heat pumps (HTHP), i.e., heat pumps delivering temperatures in the range between 100 °C and 200 °C, suitable for many industrial processes but still under development, are reviewed. Then, papers reporting innovative solutions for the integration of heat pumps in specific industrial processes and sectors (e.g., distillation, drying, desalination, etc.) are analyzed. Finally, the literature about alternative low-GWP refrigerants for industrial heat pumps, both pure compounds and mixtures, is described. It is concluded that many progresses have been realized in the last 5 years (2020–2024) regarding the identification of innovative heat pumps for industrial applications, but further research is certainly required
Nano-PCMs for enhanced energy storage and passive cooling applications
No full textIt is well known that the heat transfer associated with a phase change process is much higher than sensible enthalpy change even in forced convection. In particular, the vaporization process has been widely studied because it exploits the highest heat transfer coefficient; this heat transfer mechanism is used in both passive (i.e. heat pipes) and active (i.e. refrigerating machines) cooling devices. However, the solid liquid phase change process is another interesting possibility to reject even high heat loads, especially when they are intermittent. The term Phase Change Materials (PCMs) commonly refers to those materials, which use the solid-liquid phase change process to adsorb and then release heat loads (Mancin et al., 2015). The present work aims at investigating the feasibility of a new challenging use of Aluminum Oxide (Al2O3) and Carbon Black (CB) nanoparticles to enhance the thermal properties: thermal conductivity, specific heat, and latent heat of pure paraffin waxes to obtain a new class of PCMs, the so-called nano-PCMs. The nano-PCMs were obtained by seeding 1 wt% of nanoparticles in paraffin waxes with melting temperatures of 20 C and 25 C. The thermophysical properties were then measured to understand the effects of the nanoparticles on the thermal properties of both the solid and liquid PCM. These new nano-PCMs can represent a feasible and interesting way to mitigate or eliminate the intrinsic limitations in the use of paraffin waxes as PCMs for both energy storage and passive cooling applications
An update on the thermophysical properties data available for pure low GWP refrigerants
No full textThe process to reduce the negative environmental impact of working fluids for the HVAC&R industry is still undergoing. One of the problems to be faced with the new low GWP refrigerants is the knowledge of their thermodynamic and transport properties. Few years ago, a thorough analysis of the open literature has been performed to determine the amount of available data for the most important synthetic low GWP pure fluids. It was highlighted that only two fluids, namely R1234yf and R1234ze(E), had been extensively investigated, while there was a lack of information about the other HFOs. In this paper, an update on the state-of-the-art of scientifically-determined thermophysical properties for pure HFOs is reported
Methodologies and Techniques for Advanced Maintenance
No full textThe management of technical plants for productivity and safety is generally a complex activity, particularly when many plants in one territory are affected, quality guarantees and cost results are required, and the technology involved is heterogeneous and innovative. To enable readers to manage technical plants efficiently, despite the above complications, Methodologies and Techniques for Advanced Maintenance presents theories, methodologies and practical tools for the realization of an intelligent maintenance management system for distant monitoring. It also covers the development and running of a remote control center. The so-called granted availability management system (GrAMS) was conceived to enable organizations involved in technical-industrial plant management to move towards “well known availability” and “zero failures” management. In particular, Methodologies and Techniques for Advanced Maintenance deals with the diagnostic aspects and safety levels of technical plants (such as elevators, thermo-technical plants, etc.). The author also discusses the usage of ad hoc designed software analysis tools based on neural networks and reliability indicators. Methodologies and Techniques for Advanced Maintenance is a useful text for practitioners and researchers in maintenance and facilities. Its application spans industrial, plant, technological, infrastructure and civil fields
Il Partito comunista francese e i processi ai résistants nel secondo dopoguerra
No full textI processi giuridici intentati in Francia nel secondo dopoguerra nei confronti di ex
partigiani citati in giustizia per fatti legati al periodo della Resistenza costituiscono un terreno pressoché inesplorato dalla storiografia. L’autore ritiene che si tratti di un fenomeno importante con implicazioni molteplici sul piano politico e sociale. Nel presente lavoro si è deciso di prendere in considerazione un aspetto specifico e circoscritto dell’argomento considerato, concentrandosi sulla reazione del Partito Comunista Francese di fronte a questi processi e sul ruolo da questi giocato nella difesa dei partigiani coinvolti in procedimenti giudiziari. Nello specifico, l’autore analizza i differenti sviluppi del rapporto tra PCF e partigiani dall’immediato dopoguerra fino agli anni Cinquanta.The trials after the Second war world in France against former partisans sued for acts
related to the period of the Resistance are an almost unknown field by historians. The author believes that it is an important phenomenon with multiple implications on the political and social dimension. This work focalizes on a specific aspect of the topic, focusing on the French Communist Party’s reaction to trials against partisans and on the role that it has played in the defence of partisans involved in juridical trials. Specifically, the author analyses the different developments in the connections between PCF and partisans from the post-war period to the fifties
Ultrasound assessment as predictor of disease relapse in children and adults with arthritis in clinical stable remission: new findings but still unmet needs
No full textN
High-resolution Br γ spectro-interferometry of the transitional Herbig Ae/Be star HD 100546 : a Keplerian gaseous disc inside the inner rim
No full textACC acknowledges support from CNPq (grant 308985/2009-5). JDI gratefully acknowledges funding from the European Union FP7-2011 under grant agreement no. 284405. RGV acknowledges the support from FAPESP (grant 2012/20364-4).We present spatially and spectrally resolved Br γ emission around the planet-hosting, transitional Herbig Ae/Be star HD 100546. Aiming to gain insight into the physical origin of the line in possible relation to accretion processes, we carried out Br γ spectro-interferometry using AMBER/VLTI from three different baselines achieving spatial and spectral resolutions of 2-4 mas and 12 000. The Br γ visibility is larger than that of the continuum for all baselines. Differential phases reveal a shift between the photocentre of the Br γ line-displaced~0.6mas (0.06 au at 100 pc) NE from the star-and that of the K-band continuum emission-displaced ~0.3 mas NE from the star. The photocentres of the redshifted and blueshifted components of the Br γ line are located NW and SE from the photocentre of the peak line emission, respectively. Moreover, the photocentre of the fastest velocity bins within the spectral line tends to be closer to that of the peak emission than the photocentre of the slowest velocity bins. Our results are consistent with a Br γ-emitting region inside the dust inner rim (≲0.25 au) and extending very close to the central star, with a Keplerian, disc-like structure rotating counter-clockwise, and most probably flared (~25°). Even though the main contribution to the Br γ line does not come from gas magnetically channelled on to the star, accretion on to HD 100546 could be magnetospheric, implying a mass accretion rate of a few 10-7 M⊙ yr-1. This value indicates that the observed gas has to be replenished on time-scales of a few months to years, perhaps by planet-induced flows from the outer to the inner disc as has been reported for similar systems.Peer reviewe
- …
