1,721,267 research outputs found
Measurement of thermal diffusivity with a modified Angstrom method
No full textA methodology has been developed to measure the thermal diffusivity of high thermal conductivity solid materials. The basic idea traces back to the Ångström method, but the implementation differs in some points. Originally the specimen was free to the environment, here the specimen is thermally insulated to reduce, and control, the effects of natural convection. An appropriate analytical solution is used to calculate temperature distribution. The original two-point approach is replaced by a parameter estimation technique to consider multiple measurement points and reduce the final uncertainty. The methodology is used for a pure copper bar. The results are compared with the data available in the literature. The measured thermal diffusivity is 1.16±0.07·10-4m2/s while the most reliable data available in the literature is 1.17±0.04·10-4m2/s. The agreement of the present value with those available in the literature is excellent. This makes the use of this simple analytical approach attractive
Axial wall conduction preheating effects in high Péclet number laminar forced convection
No full textAn analytical solution for the preheating due to the wall axial conduction in forced convection heating of fully developed laminar flows, is presented. The geometry of interest consists of a long circular tube heated for a finite or semi-infinite length. It is proved that in the preheating region the wall heat flux varies with exponential law in the streamwise direction, so that the temperature profile becomes fully developed. Moreover, an exact functional relation between the exponent of the wall heat flux distribution and a single parameter, which depends on the Péclet number and the wall conductance, is derived. The practical significance of the analysis is finally discussed. Copyright © 1996 Elsevier Science Ltd
An analytical approach to fully developed heating of laminar flows in circular pipes
No full textAn analytical solution is proposed to predict the fully developed Nusselt number for laminar flow in circular pipes, as arising from exponential heating. The solution is obtained in terms of Confluent Hypergeometric Functions, characterized by fast convergence and easy implementation. Both positive and negative exponents are considered. The range of practical interest is discussed. © 1995
Healthcare associated infections in companion animals. The role of the microbiology lab in the surveillance system
No full textHospital-acquired injections (HAIs) are an emerging threat in both human and veterinary mediane. Considering the simultaneous involvement of environment, animals and humans, this problem has to be faced with a «One Health» approach. This review aims at raising the awareness about the use of surveillance systems in veterinary settings, which would allow to reduce HAIs rates in both animals and clinic personnel, decrease hospital-related economic losses and improve the reputation of the settings. The review focuses on basic keypoints needed for the implementation of these systems by highlighting microbiological aspects related with HAIs and some topics of bacteriological diagnostics applied for infection control policies and outbreaks management. Of particular importance is the communication between clinical and microbiological staff, underlining the significance of a multidisciplinary approach. Subsequently, the review describes the main typologies of surveillance that can be adopted by veterinary settings, and eventually it reports the most important bacterial agents associated with HAIs, with various examples from veterinary medicine literature
Experimental investigation of the efficiency of a spray-wetted finned tube bank
No full textThis paper presents the experimental results obtained for a three-Tiered finned tube bank with the aid of which a heat-carrying fluid heats a wet air stream entraining a water spray. A study was made of the thermal behavior of the two-phase humid-air/water-spray stream flowing over the finned tube bank when the inlet temperature of the process fluid (water) is low and the difference between the inlet temperature of the two streams (air/water mist and process fluid flow) is very small. The results are given in terms of enthalpic efficiency for both mist flow and single air flow conditions
Effects of the thermal capacitance on the daily thermal performance of a CPC: An experimental investigation
No full textThe availability of reliable models for the prediction of the daily thermal behaviour of thermal solar collectors is of great relevance for a correct design of solar thermal systems. The most significant design parameters of a solar collector are outlet temperature and useful energy collection, both calculated on the base of the efficiency. The last, in turn, is commonly available on the base of experimental correlations obtained with the Steady State Testing method proposed by EN 12975-2. In these steady state tests, through the respect of very strict requirements, the contributions due to the thermal inertia of the solar collector becomes negligible. However, in its daily behaviour, it undergoes variable weather conditions with both regular and sharp changes of solar radiation. For these conditions the thermal inertia contributions become relevant in the correct prediction of its thermal behaviour. EN 12975-2 in Annex K suggests a modified equation for the prediction of the useful energy collection, based on a modification of the efficiency equation. A term dependent on the time derivative of the mean inlet/outlet water temperature is added. In this paper we examine experimentally the role played by this term for a Compound Parabolic Concentrator solar thermal collector
A dynamic model integrating colour and shape information for objects tracking in conditions of occlusion
No full textIn this paper, an algorithm for tracking multiple rigid and non-rigid objects in conditions of occlusions is presented. The proposed method is based on a scalable and adaptive model based on joint information of color and shape. Through a GHT (Generalized Hough Transform) based voting method the center of mass of each object can be determined in real time with a good degree of precision. Quantitative and qualitative results are presented to validate efficiency of the method
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Long-term complications of COVID-19 in ICU survivors: What do we know?
Full text linkCoronavirus disease 2019 (COVID-19) has caused more than 175 million persons infected and 3.8 million deaths so far and is having a devastating impact on both low and high-income countries, in particular on hospitals and Intensive Care Units (ICU). The ICU mortality during the first pandemic wave ranged from 40% to 85% during the busiest ICU period for admissions around the peak of the surge, and those surviving are frequently faced with impairments affecting physical, cognitive, and mental health status, complicating the postacute phase of COVID-19, which in the pre-COVID period, were defined collectively as postintensive care syndrome (PICS). Long COVID is defined as four weeks of persisting symptoms after the acute illness, and post-COVID syndrome and chronic COVID-19 are the proposed terms to describe continued symptomatology for more than 12 weeks. Overall, 50% of ICU survivors suffer from new physical, mental, and/or cognitive problems at 1 year after ICU discharge. The prevalence, severity, and duration of the various impairments in ICU survivors are poorly defined, with substantial variations among published series, and may reflect differences in the timing of assessment, the outcome measured, the instruments utilized, and thresholds adopted to establish the diagnosis, the qualification of personnel delivering the tests, the resource availability as well diversity in patients' case-mix. Future longitudinal studies of adequate sample size with repeated assessments of validated outcomes and comparison with non-COVID-19 ICU patients are needed to fully explore the long-term outcome of ICU patients with COVID-19. In this article, we focus on chronic COVID-19 in ICU survivors and present state-of-the-art data regarding long-term complications related to critical illness and the treatments and organ support received
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