86,733 research outputs found
Multi-objective sensitivity analysis of shell-and-tube LHTES performance
No full textIn the present paper a sensitivity analysis has been carried out concerning the charging/discharging time and the stored energy performances of a shell-and-tube LHTES with respect to the number of tubes and the tube internal radius. The aim of this analysis is to investigate how the design variables affect the LHTES performance. this could lead to determine the thermal storage optimal design. Thus, the sensitivity analysis has a key role in the selection of several acceptable solutions. The considered LHTES exhibits a cylindrical shell geometry characterized by constant height and diameter. This aspect has allowed to employ simplified theoretical models able to predict the charging/discharging time and the stored energy performance. These models consider a constant heat exchange wall temperature whereas the heat exchange area and the whole PCM volume vary according to the design variables. This analysis represents the first step to solve the multi-objective optimization of the thermal storage design problem and then to determine the best solutions in both design variables and thermal storage performance domains
Note per una risignificazione femminista dello spazio urbano : Dalla toponomastica allo sciopero transnazionale
No full text
Effects of PEEP on intrathoracic and extrathoracic blood volumes evaluated with the COLD system in patients with acute respiratory failure. Preliminary study
No full textAIM OF THE STUDY:
To evaluate the effects of positive end expiratory pressure (PEEP) on intrathoracic and extrathoracic blood volumes in patients with acute respiratory failure (ARF).
METHODS:
In 4 ARF patients, we have measured cardiac output (CI), intrathoracic blood volume (ITBVI), global end-diastolic ventricular volume (GEDVI), pulmonary (PBVI) and total (TBVI) blood volumes, during application of two PEEP levels (0 and 10 cm H2O). These measurements have been performed by PULSION COLD Z-021 system, using the double indicator dilution technique (thermal and dye dilution).
RESULTS:
PEEP application caused a significant reduction in CI (from 3.8 +/- 0.4 to 2.9 +/- 0.1 1/min/m2) and ITBVI (from 888 +/- 48 to 698 +/- 25 ml/m2). The reduction in intrathoracic blood volume was associated with a significant reduction in GEDVI and PBVI. After PEEP application, there was a significant reduction in TBVI (from 2437 +/- 135 to 1984 +/- 49 ml/m2).
CONCLUSIONS:
PEEP application decreases cardiac index, mainly through a preload reduction, as evidenced by the reduction in intrathoracic and end-diastolic ventricular blood volumes. The preload effect is due to an increase in intrathoracic pressure with reduction in total circulating blood volume. TBVI reduction is consistent with blood pooling in vascular compartments, e.g., splanchnic compartment, characterized by long vascular time constant
Identification of differentially glycosylated forms of the soluble p75 tumor-necrosis-factor (TNF) receptor in human urine
No full textHuman urine is known to contain a 30 kDa soluble form of the p75-TNF receptor (sTNF-R2), In this work we have purified sTNF-R2 from the urine of normal subjects and further characterized its structure and activity. sTNF-R2 was resolved by reducing SDS-PAGE in a major band of 30 kDa, similar in size to the previously described urinary sTNFR2, and in a minor band of 45 kDa, ''Western'' blotting analysis with anti-TNF-R1 and anti-TNF-R2 antibodies showed that both bands were immunologically related to the membrane TNF-R2. Glycosylation studies indicated that the 30 kDa is N-glycosylated while the 45 kDa form is N- and O-glycosylated, and suggested that both forms contain terminally linked sialic acid that is differentially recognized by lectins. These results indicate that human urine contains, besides the 30 kDa form, a new form of 45 kDa characterized by different glycosylation type and degree
Utilizzo di metodi quantitativi per la pianificazione di un network di Aree Marine Protette
No full textNovel Multi-Objective Optimal Design of a Shell-and-Tube Latent Heat Thermal Energy Storage Device
No full textIn the present paper a new multi-objective optimisation procedure for the design of a shell-and-tube Latent Heat Thermal Energy Storage (LHTES) is proposed. A simple arrangement of a cylindrical shell with multiple vertical tubes has been examined. The optimisation considers, as design variables, the number of tubes, the tube internal radius and the device height-to-diameter ratio, (Formula presented.), while the storage volume is kept constant. This analysis aims to detect the set of solutions which optimises the LHTES performances evaluated in terms of charging and discharging times and overall thermal energy capacity. To accomplish the multi-objectives optimal thermal storage design, a simplified mathematical model of the LHTES has been employed. This model can evaluate the prescribed performances for a given set of design variables. The proposed optimisation procedure evaluates new solutions along the most promising directions in the design variables domain, leading to a significant improvement in storage performances. The Design of the Experiment, together with the Pareto dominance relationship, gives a starting optimal solutions subset. The proposed optimisation procedure permits to enhance the starting optimal solutions subset letting approach the Pareto barrier. The paper shows that, at the end of the optimisation procedure, the designer can select the solutions on the Pareto barrier with the best performance and the corresponding design variables for each chosen solution. The proposed optimisation procedure will also allow for maintaining low computational costs due to the low number of the new design variables evaluated only in the promising directions
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