Search results for " equivalent"
showing 10 items of 172 documents
Assessment of the Usability and Accuracy of Two-Diode Models for Photovoltaic Modules
2017
Many diode-based equivalent circuits for simulating the electrical behaviour of photovoltaic (PV) cells and panels are reported in the scientific literature. Two-diode equivalent circuits, which require more complex procedures to calculate the seven model parameters, are less numerous. The model parameters are generally calculated using the data extracted from the datasheets issued by the PV panel manufactures and adopting simplifying hypotheses and numerical solving techniques. A criterion for rating both the usability and accuracy of two-diode models is proposed in this paper with the aim of supporting researchers and designers, working in the area of PV systems, to select and use a model…
A Criterion for Rating the Usability and Accuracy of the One-Diode Models for Photovoltaic Modules
2016
In selecting a mathematical model for simulating physical behaviours, it is important to reach an acceptable compromise between analytical complexity and achievable precision. With the aim of helping researchers and designers working in the area of photovoltaic systems to make a choice among the numerous diode-based models, a criterion for rating both the usability and accuracy of one-diode models is proposed in this paper. A three-level rating scale, which considers the ease of finding the data used by the analytical procedure, the simplicity of the mathematical tools needed to perform calculations and the accuracy achieved in calculating the current and power, is used. The proposed criter…
Assessment of the Usability and Accuracy of the Simplified One-Diode Models for Photovoltaic Modules
2016
Models for photovoltaic (PV) cells and panels, based on the diode equivalent circuit, have been widely used because they are effective tools for system design. Many authors have presented simplified one-diode models whose three or four parameters are calculated using the data extracted from the datasheets issued by PV panel manufactures and adopting some simplifying hypotheses and numerical solving techniques. Sometimes it may be difficult to make a choice among so many models. To help researchers and designers working in the area of photovoltaic systems in selecting the model that is fit for purpose, a criterion for rating both the usability and accuracy of simplified one-diode models is p…
Analysis of local shear effects in brick masonry infilled RC frames
2013
Masonry infills panels placed among framed structures meshes have a relevant influence in presence seismic actions in terms of strength stiffness and global displacement capacity. In the case of RC structures, the modifications of internal forces due to infill-frame interaction may be not compatible with surrounding frame members strength especially considering additional shear forces arising at the ends of beams and columns in contact with the panel under lateral actions. Such effects may be in many cases the cause of unexpected brittle collapse mechanisms which compromise the safety of the entire structure. In this paper by means of a double (micromodeling and macromodeling) procedure reg…
Midlife fitness predicts less burden of chronic disease in later life.
2013
OBJECTIVE: To investigate the relationship between midlife fitness in healthy adults and the development of nonfatal chronic conditions (CCs) in older age. DESIGN: Cohort study. SETTING: Data on participants were drawn from the Cooper Center Longitudinal Study and linked with US Medicare claims made in the years 1999 through 2009. PARTICIPANTS: The cohort included 18 670 participants (median age, 49 years; 21% women) who had received a comprehensive clinical examination between 1970 and 2009 at the Cooper Center, were ≥65 years of age and covered by Medicare between 1999 and 2009, and who reported no baseline history of CCs such as cardiovascular disease, diabetes, and cancer. The participa…
A New Low Background Laboratory in the Pyhäsalmi Mine : Towards 14C free liquid scintillator for low energy neutrino experiments
2017
A new low background laboratory in Pyhäsalmi mine in the Central Finland has been put into operation in the beginning of 2017. The laboratory operates at the depth of 1436 m (~4100 meters of water equivalent). In this paper, we present description of the laboratory’s existing facility and background conditions. In the laboratory, a series of measurements has been started where the 14C concentration is determined from several liquid scintillator samples. A dedicated setup has been designed and constructed with the aim of measuring the 14C/12C ratio smaller than 10-18 . peerReviewed
Effectiveness of postoperative home-exercise compared with usual care on kinesiophobia and physical activity in spondylolisthesis:A randomized contro…
2017
Objective: To study the effectiveness of a 12-month exercise therapy on kinesiophobia and physical activity in patients with spondylolisthesis after lumbar spine fusion. Design: Randomized controlled trial. Subjects: Patients (n = 98) with spondylolisthesis who had undergone lumbar spine fusion. Methods: All patients (mean age 59 years) had received lumbar spine fusion surgery and identical postoperative instructions. Three months postoperatively, they were randomized into an exercise group (n = 48) or usual care group (n = 50). The exercise group received 12-month progressive home-based training with regular booster sessions, and the usual care group a single session of physiotherapy instr…
Perceived physical competence towards physical activity, and motivation and enjoyment in physical education as longitudinal predictors of adolescents…
2015
Abstract Objectives The aim of the study was to investigate if adolescents' perceived physical competence towards physical activity (PA), and autonomous motivation and enjoyment in physical education (PE) during early adolescence can predict amount and intensity of self-reported physical activity six years later. Design This study utilized a 6-year longitudinal data set collected within Finnish school settings. Students responded to questionnaires measuring their perceived physical competence towards physical activity, and autonomous motivation and enjoyment in PE during their first year at middle school (Grade 7), and their PA engagement during their last year in high school (Grade 12). Me…
Self-reported fitness and objectively measured physical activity profile among older adults : a twin study
2018
Abstract Background Maintaining good fitness and good level of physical activity are important factors for maintaining physical independence later in life. The aim was to investigate the relationship between self-reported fitness and objectively measured physical activity and sedentary behavior in the elderly. Methods Same-sex twin pairs born 1940–1944 in Finland were invited to the study. Altogether 787 individuals (mean age 72.9 years), of whom 404 were female, used a hip-worn triaxial accelerometer for at least 4 days and answered a question on perceived fitness. First, individual differences were studied between four fitness categories. Second, pairwise differences were examined among t…
Individual Scaling of Accelerometry to Preferred Walking Speed in the Assessment of Physical Activity in Older Adults
2020
Abstract Background Walking forms a large portion of physical activity (PA) of older adults. We assessed free-living PA using acceleration corresponding to preferred walking speed as a relative cut-point and studied how it relates to age. We compared the relative cut-point to a common absolute cut-point of moderate-to-vigorous physical activity (MVPA). Method Four hundred forty-four community-dwelling adults aged 75, 80, and 85 years wore an accelerometer on the thigh during a PA surveillance period and a modified 6-minute walking test (6MWT) at preferred speed. Each individual’s mean acceleration (g) during the 6MWT was used as a cut-point for relative PA. Acceleration corresponding to thr…