1,720,979 research outputs found
Modelling the population dynamics of Daphnia obtusa (Kurz) in Lake Orta (N. Italy) under pre- and post-liming conditions
No full textA mathematical matrix model was formulated to investigate the response of Daphnia obtusa population dynamics to the changes in the water chemistry of Lake Orta before and after the liming operation. Modelparameters were estimated from experimental laboratory data. Model analysis showed that water chemistry changes induced by liming affected mainly egg survival and predicted the highest population growth at pH 6. Whereas increased egg mortality heavily inhibits population growth rate, the model still predicts a long term tendency of the population to increase in number. However, both before and after the liming operation due to high food availability in the laboratory, egg production was higher under all experimental conditions than in the field. When food limitation is accounted for and more realistic, field based estimates of egg production are used, the model predicts the extinction of D. obtusa population in the lake. This suggests that the effects of water chemistry changes on egg mortality had a critical role in the disappearance of D. obtusa from Lake Orta and may even adequately explain the extinction of this population
Indoor investigations and computational fluid-dynamics analysis applied for designing the HVAC system of the Wedding Chamber (Camera Picta) in Mantova
No full textComposizione ed evoluzione della biocenosi zooplanctonica nei laghi di Suviana e Brasimone (Appennino Tosco-Emiliano)
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Parental allocation in Acipenser naccarii –statistical aspects and software development.
No full textMicroclimate analysis of the Scrovegni Chapel in Padua: measurements and simulations
No full textThis paper presents a detailed analysis of the microclimate within an historical building: the Scrovegni Chapel in Padua, Italy. The measured values, obtained over an extended periodo of time, provide information useful for the conservation of the frescos. The primary task was management of the microclimate: air temperature, air velocity and air humidity are the main physical properties that must be controlled. The indoor air quality and the numeber of air changes should also be controlled, specially where the presence of people can be a significant source of pollution. To evaluate the effects of management policies, including the installation of an HVAC (heating ventilation and air conditioning) system, some numerical simulations were performed. CFD (computational fluid dynamics) calculatons supplement the information obtained from field measurements. A proposal for the control of air flow rates and of the interior microclimate is presented
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
A process and a device for the artificial insemination of bovids, specifically of buffaloes
No full textAssessment of offshore liquid hydrogen production from wind power for ship refueling
No full textGreen hydrogen from electrolysis has become the most attractive energy carrier for making the transition from fossil fuels to carbon-free energy sources possible. Especially in the naval sector, hydrogen has the potential to address environmental targets due to the lack of low-carbon fuel options. This study aims at investigating an offshore liquefied green hydrogen production plant for ship refueling. The plant comprises a wind farm for renewable electricity generation, an electrolyzer stack for hydrogen production, a water treatment unit for demineralized water production, and a hydrogen liquefaction plant for hydrogen storage and distribution to ships. A pre-feasibility study is addressed to find the optimal capacities of the plant that minimize the payback time. The model results show that the electrolyzer capacity shall be set equal to a value between 80% and 90% of the wind farm capacity to achieve the minimum payback times. Additionally, the wind farm capacity shall be higher than about 150 MW to limit the payback time to values lower than 11 years for a fixed hydrogen price of 6 €/kg. The Levelized Cost of Hydrogen results to be below 4 €/kg for a wide range of plant capacities for a lifetime of the plant of 25 years. Thus, the model shows that this plant is economically feasible and can be reproduced similarly for different locations by rescaling the different selected technologies. In this way, the naval sector can be decarbonized thanks to a new infrastructure for the production and refueling of liquified green hydrogen directly provided on the sea
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