179 research outputs found
Thermophysical Property Estimation by Transient Experiments: The Effect of a Biased Initial Temperature Distribution
The identification of thermophysical properties of materials in dynamic experiments can be conveniently performed by the inverse solution of the associated heat conduction problem (IHCP). The inverse technique demands the knowledge of the initial temperature distribution within the material. As only a limited number of temperature sensors (or no sensor at all) are arranged inside the test specimen, the knowledge of the initial temperature distribution is affected by some uncertainty. This uncertainty, together with other possible sources of bias in the experimental procedure, will propagate in the estimation process and the accuracy of the reconstructed thermophysical property values could deteriorate. In this work the effect on the estimated thermophysical properties due to errors in the initial temperature distribution is investigated along with a practical method to quantify this effect. Furthermore, a technique for compensating this kind of bias is proposed. The method consists in including the initial temperature distribution among the unknown functions to be estimated. In this way the effect of the initial bias is removed and the accuracy of the identified thermophysical property values is highly improved
Encouraging MSK imaging research towards clinical impact is a necessity: opinion paper of the European Society of Musculoskeletal Radiology (ESSR)
Radiology has not been spared in recent economic crises with a substantial reduction in the turnover of imaging equipment. These problems are exacerbated by increasing demand for healthcare across Europe. Therefore, using existing radiological services while rigorously following evidence-based guidelines might improve patient care. Thus, diagnostic pathways should be assessed not only for technical and diagnostic performance but also for their impact on medical and social outcome. In this paper, we report the advice of the Research Committee of ESSR on how we may guide musculoskeletal radiological research towards studies that have useful clinical impact. The ESSR Research Committee intends to encourage research with potential to influence treatment, patient outcome, and social impact. Key Points \u2022 Research in medical imaging has the potential to improve human health. \u2022 High-level studies have the potential to place radiology at the pinnacle of quality in evidence-based practice. \u2022 The ESSR Research Committee intends to encourage research with potential to influence treatment, patient outcome, and social impact
Reliability Analysis and Economic Evaluation of Thermal Reflective Insulators
High-performance thermal insulators allow a dramatic reduction in the thickness of coatings, thanks to their low thermal conductivity. This study provides an overview about thermal insulation materials, with regards to heat reflective insulators in particular. Then, the numerical investigation method adopted to compute the thermal resistance associated with reflective insulators is introduced. This method has been used in turn to check the accuracy of the declared, measured performance of different, heat-reflective materials on the market. Many manufacturers of reflective insulators were available to provide information and a good agreement between the declared and expected thermal resistance has been found. The choice of a non-experimental approach is meant to check the validity of an already performed test on a reflective insulator using a predictive approach instead of standard, additional testing. Then, the insulation of five typical walls at three different sites in Italy has been simulated, showing that most of heat-reflective materials cannot achieve the maximum required transmittance. Interstitial condensation is likely to occur in specific cases, also because of the aluminum layers inside. The economic analyses showed comparable costs for both heat reflective and traditional insulators, and their cost effectiveness needs to be evaluated case by case
Implementation of a cogeneration plant for a food processing facility. A case study
The present work presents an investigation regarding the feasibility analysis of a cogeneration plant for a food processing facility with the aim to decrease the cost of energy supply. The monthly electricity and heat consumption profiles are analyzed, in order to understand the consumption profiles, as well as the costs of the current furniture of electricity and gas. Then, a detailed thermodynamic model of the cogeneration cycle is implemented and the investment costs are linked to the thermodynamic variables by means of cost functions. The optimal electricity power of the co-generator is determined with reference to various investment indexes. The analysis highlights that the optimal dimension varies according to the chosen indicator, therefore it is not possible to establish it univocally, but it depends on the financial/economic strategy of the company through the considered investment index
Effect on the energy market of the potential switching to heat pumps for space heating
The main subject of this work is to understand what could happen in the Italian electricity market if a given share of building heating demand had switched from gas to electricity heating devices. The objective is to define the optimal share to switch in terms of minimization of environmental (CO2) emissions. The effects of such switching on the national energy system are analyzed from the financial point of view, depending also on the heating habits of final users. An hourly simulation of the electricity market has been performed by means of a bid stack model (BIDSM) developed at University of Genoa, calculating market prices, power plant generation typology, fuel consumption and global CO2 emissions. All the data are averaged on a national basis and results are reported for two different time schedule of heating requirements of the final users. In each case, the total energy consumption is fixed, and local "degree days" and location energy needs are considered. It seems that the use of heat pumps for building heating is a real option and that the user habits has a little impact on optimal share of switching from gas to heat pumps, at least concerning CO2 emission minimization
Optimal Regulation Criteria for Building Heating System by Using Lumped Dynamic Models
Abstract Energy efficiency of buildings has gained an important role with respect to possible energy saving policy measures, mainly for space heating demand which represents the dominant energy end-use. The present contribution addresses the problem of estimating building heating energy consumptions by using numerical models able to simulate the dynamic interaction between the building and the heating system. A dynamic numerical code in the Engineering Equation Solver (EES) is developed to simulate both building and heating system and the influence of heating system regulation criteria on different parameters (mainly energy saving and internal comfort) is investigated in an optimization perspective
A novel TRNSYS type for short-term borehole heat exchanger simulation: B2G model
[EN] Models of ground source heat pump (GSHP) systems are used as an aid for the correct design and optimization of the system. For this purpose, it is necessary to develop models which correctly reproduce the dynamic thermal behavior of each component in a short-term basis. Since the borehole heat exchanger (BHE) is one of the main components, special attention should be paid to ensuring a good accuracy on the prediction of the short-term response of the boreholes. The BHE models found in literature which are suitable for short-term simulations usually present high computational costs. In this work, a novel TRNSYS type implementing a borehole-to-ground (B2G) model, developed for modeling the short-term dynamic performance of a BHE with low computational cost, is presented. The model has been validated against experimental data from a GSHP system located at Universitat Politecnica de Valencia, Spain. Validation results show the ability of the model to reproduce the short-term behavior of the borehole, both for a step-test and under normal operating conditions. (C) 2015 Elsevier Ltd. All rights reserved.The present work has been supported by the FP7 European project Advanced ground source heat pump systems for heating and cooling in Mediterranean climate (GROUND-MED).De Rosa, M.; Ruiz Calvo, F.; Corberán Salvador, JM.; Montagud Montalvá, CI.; Tagliafico, L. (2015). A novel TRNSYS type for short-term borehole heat exchanger simulation: B2G model. Energy Conversion and Management. 100:347-357. https://doi.org/10.1016/j.enconman.2015.05.021S34735710
Safety and tolerability of intravenous ferric carboxymaltose in the oldest old patients: a prospective cohort study in a University Italian Geriatrics Department
Background & aims. Anemia is common in older adults and it is associated with relevant complications. Although anemia is often multifactorial in origin and iron deficiency is considered a key relevant causative factor. The first therapeutic option is oral iron supplementation, but it is frequently characterized by adverse effects and overall poor efficacy. So far, intravenous (i.v.) iron formulations may serve as alternative treatment options and, in particular, Ferric carboxymaltose (FCM), showed to be safe and effective in older patients. We aimed to assess the safety and tolerability of FCM in real world hospitalized frail oldest old patients. Methods.This is an observational prospective study on 25 old age patients with iron deficiency anemia (IDA), admitted between July 2019 and November 2019 to the Geriatric Clinical ward of the IRCCS Policlinico San Martino, Genoa, Italy and treated with i.v. FCM. The incidence, probability and severity of adverse drug reactions (ADR) were reported along with the clinical response in term of mean Haemoglobin (Hb) increase after one week from the drug administration. Results. 72% of patients were oldest old with IDA and the clinical phenotype was characterized by multimorbidity and disability. The mean dose of i.v. FCM was 1160.0 ± 313.6 mg. FCM resulted safe therapeutic option with overall good tolerability. Additionally, a significant clinical improvement in the mean Hb level was observed. Conclusions. These findings moved a step in the recommendation of i.v. iron supplementation as a preferable route in oldest old, serving as a potential platform for future randomized clinical studies
Measuring calf circumference in frail hospitalized older adults and prediction of in-hospital complications and post-discharge mortality
BackgroundSarcopenia, characterized by muscle mass, strength, and performance decline, significantly impacts outcomes in older adults. This study aims to assess the predictive value of calf circumference (CC), in conjunction with SARC-F and hand grip, concerning in-hospital complications and post-discharge mortality among hospitalized frail older adults.MethodsA cohort of 158 hospitalized patients aged over 65 years underwent Comprehensive Geriatric Assessment and sarcopenia screening, including CC measurement. Multivariable regression analyses, adjusted for confounders, were conducted to assess predictive associations.ResultsThe study cohort, comprising 53% males with a median age of 86 years, exhibited significant sarcopenia prevalence based on SARC-F (85% indicating sarcopenia), hand grip strength (probable sarcopenia in 77% of males and 72% of females), and CC (sarcopenia in 83%). Multivariate analysis, adjusting for age, sex, Clinical Frailty Scale (CFS), and Mini Nutritional Assessment-Short Form (MNA-SF), demonstrated associations of CC and SARC-F with in-hospital complications, while CC also showed a significant association with reduced risks of in-hospital mortality (OR 0.441, 95% CI 0.257 to 0.754, p = 0.003) and 90-day mortality (OR 0.714, 95% CI 0.516 to 0.988, p = 0.043).ConclusionThis study provides insights into the predictive accuracy of sarcopenia screening tools on mortality in real-world hospitalized older adults with frailty. Notably, CC emerges as a robust predictor of mortality outcomes. Further research is warranted to validate and elucidate the respective contributions of CC and frailty to mortality in vulnerable populations
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