529 research outputs found
Traditional Houses with Stone Walls in Temperate Climates: The Impact of Various Insulation Strategies
The present chapter focuses on the yearly behaviour of a traditional farmhouse in a
temperate Italian climate and analyses the impact of alternative energy saving strategies on
summer comfort and winter consumptions.
The aim of the current study was to:
- identify combinations of thermal insulation interventions which: optimise winter
energy saving and summer internal comfort without modifying the close relationship
between architecture and specific climate typical of traditional buildings; respect the
building material consistency and the façades aesthetic appearance.
- compare the performance of this traditional architecture (after the retrofit intervention)
with that of a modern building, of the type encouraged by new energy saving
legislation (lightweight and super-insulated).
To that aim a series of monitoring activities in summer and in winter were carried out to
investigate the internal environmental conditions and to calibrate a simulation model with
the software Energyplus. This model was used to assess the impact of various energy-saving
strategies on winter energy consumptions and summer comfort with the method of
Percentage outside the comfort range (EN 15251:2007-08)
A Macroscopic Mathematical Model For Cell Migration Assays Using A Real-Time Cell Analysis
Experiments of cell migration and chemotaxis assays have been classically
performed in the so-called Boyden Chambers. A recent technology, xCELLigence
Real Time Cell Analysis, is now allowing to monitor the cell migration in real
time. This technology measures impedance changes caused by the gradual increase
of electrode surface occupation by cells during the course of time and provide
a Cell Index which is proportional to cellular morphology, spreading, ruffling
and adhesion quality as well as cell number. In this paper we propose a
macroscopic mathematical model, based on \emph{advection-reaction-diffusion}
partial differential equations, describing the cell migration assay using the
real-time technology. We carried out numerical simulations to compare simulated
model dynamics with data of observed biological experiments on three different
cell lines and in two experimental settings: absence of chemotactic signals
(basal migration) and presence of a chemoattractant. Overall we conclude that
our minimal mathematical model is able to describe the phenomenon in the real
time scale and numerical results show a good agreement with the experimental
evidences
Experimental Investigation On A Novel Two-Stage Sliding-Vane Air Compressor Based On The Intracooling Concept
Intercooling is a well-known practice in compression technology for reducing the discharge temperature and the power consumption of the process. Intracooling, a similar yet not identical concept, is the cooling of the compressed gas between two compression stages by way of spraying a liquid coolant in the gas flow without separating that liquid prior to the second compression stage. This liquid coolant can be the cooled lube oil. The present work reports the experimental experience on a first prototype of a small-scale two-stage sliding-vane compressor based on the concept. The prototype is design for a relatively low delivery pressure, 0.7-1.0 MPa. Moreover, it is characterized by an oil injection system comprising pressure-swirl nozzles placed on the end-plates of the compression stages and along the intracooling duct. This duct is equipped with eight nozzles: six of them perform a radial inward injection and are equally spaced on the tube length, while the other two are located at its ends for an axial injection, one cocurrent and the other countercurrent to the air flow direction. The experimental tests differ by the number and the position of the active nozzles along the duct. The outcomes indicate that intracooling does not yield operability issues and that the intracooling effectiveness increases with the number of active pressure-swirl nozzles, reaching a decrease in temperature along the duct of about 5°C. However, the configuration with the lowest mechanical specific power, by 4.4% with respect to a single-stage compressor, has only one nozzle active and spraying along the axial flow direction. The results suggest that the compromise among oil flow rate, number of active nozzles and their position, is the best solution to obtain the maximum efficiency for the overall system. In the future, an improved intracooling duct and a mid-size intracooled compressor for higher pressures will be manufactured and tested
Gridding Effects on CO2 Trapping in Deep Saline Aquifers
Three-dimensional numerical models of potential underground storage and compositional simulation are a way to study the feasibility of storing carbon dioxide in the existing geological formations. However, the results of the simulations are affected by many numerical parameters, and we proved that the refinement of the model grid is one of them. In this study, the impact of grid discretization on CO2 trapping when the CO2 is injected into a deep saline aquifer was investigated. Initially, the well bottom-hole pressure profiles during the CO2 injection were simulated using four different grids. As expected, the results confirmed that the overpressure reached during injection is strongly affected by gridding, with coarse grids leading to non-representative values unless a suitable ramp-up CO2 injection strategy is adopted. Then, the same grids were used to simulate the storage behavior after CO2 injection so as to assess whether space discretization would also affect the simulation of the quantity of CO2 trapped by the different mechanisms. A comparison of the obtained results showed that there is also a significant impact of the model gridding on the simulated amount of CO2 permanently trapped in the aquifer by residual and solubility trapping, especially during the few hundred years following injection. Conversely, stratigraphic/hydrodynamic trapping, initially confining the CO2 underground due to an impermeable caprock, does not depend on gridding, whereas significant mineral trapping would typically occur over a geological timescale. The conclusions are that a fine discretization, which is acknowledged to be needed for a reliable description of the pressure evolution during injection, is also highly recommended to obtain representative results when simulating CO2 trapping in the subsurface. However, the expedients on CO2 injection allow one to perform reliable simulations even when coarse grids are adopted. Permanently trapped CO2 would not be correctly quantified with coarse grids, but a reliable assessment can be performed on a small, fine-grid model, with the results then extended to the large, coarse-grid model. The issue is particularly relevant because storage safety is strictly connected to CO2 permanent trapping over time
Validazione di uno strumento per valutare la partecipazione alle attivitĂ extracurriculari in area STEM. Il questionario Science Activities Evaluation Engagement (SAEE)
In this study, we present a new questionnaire, the Science Activities Evaluation Engagement (SAEE) instrument, for the evaluation of the studentsâ engagement in STEM oriented extra-curricular activities. The questionnaire was administered to about 1000 secondary school students who participated in the activities of the Piano Nazionale Lauree Scientifiche in Biology, Chemistry and Physics. Through an exploratory and confirmatory factor analysis, it was possible to validate a four-factor structure of the instrument: Satisfaction with the followed activities; Utility of the activities; Difficulties in following the activities; Involvement of close people. The obtained factor structure shows a good model fit, with each of the obtained scales showing an excellent reliability. Criterion validity was established through the academic motivation scale. The proposed instrument shows also an adequate convergent validity and a sufficient discriminant validity. Implications of the study for the evaluation of Third Mission activities of the Italian universities are also briefly discussed
Clinical pitfalls of leishmaniasis and Whippleâs disease hidden behind systemic lupus erythematosus: A case series
Systemic lupus erythematosus (SLE) is a multisystemic autoimmune disease that can affect major organs possibly leading to life-threatening complications and appears with heterogeneous clinical picture. SLE could present with broad spectrum of clinical and laboratory features that can resemble those of other diseases, such as hemopoietic malignancies, infections, or immune-mediated disorders. Its complexity and protean features overlap with many other diseases, hindering the differential diagnosis. Rarely, true overlap with other diseases may occur. Herein, we report a case series of two patients affected by infectious diseases, namely visceral leishmaniasis and Whippleâs disease (WD), intertwined with clinical or serological features of SLE. In both cases, several confounding factors have led to a delay in the diagnosis. Moreover, we first describe the persistent elevation of autoantibodies and a monoclonal gammopathy in a patient with WD. Awareness of unusual presentations of infections or other rare disorders, which may be encountered in clinical practice when taking care of SLE patients, is essential for timely diagnosis and treatment of potentially lethal diseases
Power Minimizing MEC Offloading with QoS Constraints over RIS-Empowered Communications
This work lies at the intersection of two cutting edge technologies
envisioned to proliferate in future 6G wireless systems: Multi-access Edge
Computing (MEC) and Reconfigurable Intelligent Surfaces (RISs). While the
former will bring a powerful information technology environment at the wireless
edge, the latter will enhance communication performance, thanks to the
possibility of adapting wireless propagation as per end users' convenience,
according to specific service requirements. We propose a joint optimization of
radio, computing, and wireless environment reconfiguration through an RIS, with
the goal of enabling low power computation offloading services with reliability
guarantees. Going beyond previous works on this topic, multi-carrier frequency
selective RIS elements' responses and wireless channels are considered. This
opens new challenges in RIS optimization, accounting for frequency dependent
RIS response profiles, which strongly affect RIS-aided wireless links and, as a
consequence, MEC service performance. We formulate an optimization problem
accounting for short and long-term constraints involving device transmit power
allocation across multiple subcarriers and local computing resources, as well
as RIS reconfiguration parameters according to a recently developed Lorentzian
model. Besides a theoretical optimization framework, numerical results show the
effectiveness of the proposed method in enabling low power reliable computation
offloading over RIS-aided frequency selective channels.Comment: IEEE GLOBECOM 202
- âŠ