1,721,093 research outputs found
Giovanna Zaniolo: An inspiring scientist, teacher, mentor, and colleague. Active: 1967–2012
Full text linkPower enhancement and energy efficiency of a wind turbine equipped with a slotted jet: 3D-DDES numerical simulations of the S809 airfoil
Full text linkRenewable energy sources are increasingly meeting global energy demands, with solar power leading the way and being closely followed by wind energy. For this reason, scientific research is focused on finding new ways to maximise the power generated by wind turbines, utilising both passive and active circulation control devices. This paper aims to investigate the aerodynamic performance of the NREL Phase VI wind turbine using the blade element momentum (BEM) theory and computational fluid dynamics (CFD). The baseline configuration, consisting of an S809 airfoil, is modified to employ trailing edge blowing technology, an active circulation control technique known as Coanda Jet. Calculations are performed via 3D Delayed Detached Eddy Simulation (DDES) to solve the three-dimensional flow structures over the airfoil correctly. Variations in chord and twist angle along the blade’s radius are taken into account by analysing five distinct radial positions and, by using Blade Element Momentum (BEM) theory, the total power output generated by the wind turbine is calculated. Simulations are performed at a fixed absolute wind speed equal to 7 m/s, both with and without jet blowing, employing three different jet momentum coefficients Cμ to evaluate the improvements in the examined sections' aerodynamic performance and assess the energy efficiency of the used technology. Results indicate a notable increase in lift, which consequently enhances both torque and thrust, leading to a net power gain of up to 25.1% compared to the baseline case
A 3D-DDES numerical simulation of jet blowing as a power enhancement technique applied to a wind turbine with S809 profile
No full textThe aerodynamic performance of the NREL Phase VI wind turbine is investigated through the use of the blade element momentum (BEM) theory and computational fluid dynamics (CFD). The baseline configuration, consisting of a S809 airfoil, is modified to employ trailing edge blowing technology, an active circulation control technique known as Coanda Jet. Calculations are performed via 3D Delayed Detached Eddy Simulation (DDES) to solve the three-dimensional flow structures over the airfoil correctly. A preliminary campaign of simulations is first conducted for a wide range of angles of attack from α = 0° to α = 20° on an airfoil with chord c = 0.482 m with a wind speed equal to 29.3 m/s, which corresponds to the chord at 75% of the blade radius and the relative wind velocity it experiences respectively. Results are confronted with experiments to validate the model. Once mesh fidelity is proven, five different radial positions along the blade are considered and simulations are performed with and without jet blowing to prove its efficiency. Results show that lift and thrust force both increase, enhancing net power generated by the wind turbine, which is calculated via BEM
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
Acupuncture and Neurotrophin Modulation in Neurobiology of Acupuncture
No full textThe Western explanation for acupuncture effectiveness is based upon more than half a
century of basic and clinical research, which identified the activation of sensory system
and the subsequent activity-dependent regulation of neurotransmitters, neurohormones,
and several classes of neuromodulators as plausible mechanism for the acupuncture's
therapeutic properties. The regulation of neurotrophins' expression and
activity is one of the possible neurophysiological mechanisms underlying acupuncture's
effects on neuropathic pain, nerve injury, neurodegeneration, and even in the regulation
of gonadal functions. The present work will review the scientific literature produced
by a decade of investigations on the relationship between acupuncture and neurotrophins.
This scientific production and the current knowledge about the neural and
neurohormonal activity-dependent regulation of neurotrophin expression/action suggest
the existence of a link between the ability of acupuncture in regulating neural physiology
and its effects on the neurotrophic milieu in different disease state
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Nerve growth factor release by human synovial fibroblasts prior to and following exposure to tumor necrosis factor-alpha, interleukin-1 beta and cholecystokinin-8: the possible role of NGF in the inflammatory response.
No full textOBJECTIVE:
Aim of this study was to investigate the synthesis, release and effects of nerve growth factor (NGF) in human synovial cells isolated from synovial tissue specimen from healthy and osteoarthritis (OA) patients.
METHODS:
Human synovial fibroblasts cultures were established starting from healthy and osteoarthritis patients. NGF protein levels in the culture medium, NGFmRNA and high-affinity NGF receptor (Tyrosine kinase A: TrkA) expression in the cells were evaluated in basal conditions and after stimulation with pro-inflammatory cytokines or with the neuropeptide cholecystokinin-8 (CCK-8). The effect of NGF supplement to culture medium on cell proliferation, TrkA expression, and tumour necrosis factor-alpha (TNF-alpha) and inducible-nitric oxide synthase (iNOS) production was investigated.
RESULTS:
Under basal conditions human synovial cells produce and release NGF. Both interleukin-1-beta (IL-1 beta) and TNF-alpha, but not CCK-8 promote NGF synthesis and release from OA cells. TrkA NGF receptors are also expressed in both normal and OA synovial cells. NGF, but not IL-1 beta, TNF-alpha and CCK-8, enhances the expression of TrkA in isolated synovial cells. NGF down-regulates IL-1 beta-induced TNF-alpha and iNOS production by OA synovial fibroblasts.
CONCLUSIONS:
NGF is produced and released and TrkA receptors are expressed in synovial inflammation. Overexpression of NGF in inflammed joints might be involved in the modulation rather than in the induction of the joint inflammatory response
3D reconstruction of structures of hatched larva and young juvenile of the larvacean Oikopleura dioica using SBF-SEM
Full text linkThe larvacean Oikopleura dioica is a planktonic chordate and an emerging model organism with a short life cycle of 5 days that belongs toTunicata (Urochordata), the sister clade of vertebrates. It is characterized by the rapid development of a tadpole-shaped body. Organ formation in the trunk proceeds within 7 h after the hatching of the tailbud larvae at 3 h after fertilization (hpf) and is completed at 10 hpf, giving rise to fully functional juveniles as miniature adult form. Serial block face scanning electron microscopy was used to acquire ~ 2000 serial transverse section images of a 3 hpf larva and a 10 hpf juvenile to characterize the structures and cellular composition of the trunk and organs using 3D images and movies. Germ cells were found to fuse and establish a central syncytial cell in the gonad as early as 10 hpf. Larval development gave rise to functional organs after several rounds of cell division through trunk morphogenesis. The feature would make O. dioica ideal for analyzing cellular behaviors during morphogenetic processes using live imaging. The detailed descriptions of the larvae and juveniles provided in this study can be utilized as the start and end points of organ morphogenesis in this rapidly developing organism
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