150 research outputs found

    A new islanding detection scheme based on combination of slantlet transform and probabilistic neural network for grid-tied photovoltaic system

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    According to find islanding in a grid tied photovoltaic system, a combination of Slantlet Transform (SLT) and Probabilistic Neural Network (PNN) has been proposed in this paper. The SLT is used to extract the unique features from three phase voltage signals at the Point of Common Coupling (PCC). The produced features vector is fed to a probabilistic neural network classifier as input pattern which is used to predict islanding condition. The proposed technique is validated through comparing with islanding response time in different situations with the offered response time through Rate of Change of Frequency (ROCOF) method

    STR-925: BONDING BEHAVIOR IN BRIDGE STEEL-REINFORCED ELASTOMERIC ISOLATORS

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    Steel-reinforced elastomeric isolators (SREIs) have been shown to be efficient devices to protect structures against moderate and severe earthquakes by isolating them from ground motions. Bridge elastomeric isolators, however, deteriorate when undergone repetitive loading cycles due to either earthquakes or traffic loadings. One major damage type observed dominantly in these devices is delamination or de-bonding between rubber and supporting plates and steel reinforcements, if cold-bonded. This paper investigates potential damage scenarios likely to occur in cold-bonded bridge SREIs. It also looks into bonding properties of rubber and steel in tension and shear, the two important functional characteristics of elastomeric isolators. In this study, experimental tests are employed in order to observe the bonding behavior between rubber and steel. Damage states have been organized and it is observed that the adhesive properties and level of shear deformations govern bonding characteristics

    Petrogenesis of the Lalezar granitoid intrusions (Kerman Province – Iran)

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    The Lalezar granitoids crop out within volcanic successions of the Urumieh-Dokhtar Magmatic Assemblage (UDMA). These granitoids have a range from gabbro-diorites to granites in composition. The mineral compositions of the most felsic rocks are characterized by the abundances of Na-plagioclase, quartz, alkali feldspar, biotite and hornblende. In the gabbro-diorite rocks, plagioclase (Ca-rich), hornblende, biotite and clinopyroxene are the most common minerals. Major element geochemical data show that the Lalezar granitoids are mostly metaluminous, although the most felsic members (granites) attain slightly peraluminous compositions and that they have features typical of high-K calc-alkaline rocks. In primitive mantle-normalized trace element spider diagrams, the analysed samples display strong enrichment in LILE compared to HFSE, accompanied by negative anomalies of Nb,Ta and Ti. REE chondrite-normalized plots show moderate LREE enrichment with slight to strong negative Eu anomalies. Rb–Sr geochronological data, mainly dependent on the Sr isotopic composition of biotite, was obtained in two samples and it points to 15-16 Ma. As a probable, age for the emplacement of the studied intrusives. Initial 87Sr/86Sr ratios and ƐNdi values range from 0.70495 to 0.70565 from +3.1 to +1.5 respectively, which fit into a supra-subduction mantle wedge source for the parental melts and indicates that, in general, crustal contribution for magma diversification was not relevant. Geochemical and isotopic evidence reveal that the Lalezar intrusions are cogenetic I-type granitoids which were generated in a continental arc setting, in agreement with models previously presented in the UDMA

    Petrology, geochemistry and tectonomagmatic evolution of Hezar Igneous Complex (Rayen - south of Kerman - Iran): the first description of an arc remnant of the Neotethyan subduction zone

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    The Hezar Igneous Complex (HIC) in the south-eastern part of Urumieh-Dokhtar magmatic arc, is the most prominent magmatic feature in the Kerman Porphyry Copper Belt, that understanding magmatic evolution of which may shed light on the tectonomagmatic development of this less-studied part of an important magmatic arc in the Neotethys realm. The HIC has been developed in the the intersection of the N-S striking Sabzevaran fault and the NW-SE striking Rafsanjan-Rayen fault. It is indicated that the possible place of the conduit and vent is in Jalas Mountain which has been splitted later by the Sabzevaran fault into Minor and Major Jalas. The current summit had been constructed by ascending magma chamber under the HIC that constitutes the Kamali Mountain at the south of the summit. Some plutonic rocks of the HIC are exposed at Kamali Mountain. The subalkaline rocks of this complex mainly are composed of different pyroclastic and lava flow rocks, acidic to basic in composition, showing the evidences of fractional crystallization and mineral segregation. Sequential explosive and effusive eruptions with Strombolian to Vulcanian types are evident in the successive volcanic layers. The compositional trend shows the melting of spinel lherzolite, not garnet lherzolite. The subduction-related mechanism of the magma genesis has been indicated by IAB nature of the magma formation in geochemical diagrams.publishe

    Geochemistry of granitoids of the Lalezar area (Kerman, Iran)

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    The Lalezar granitoids crop out within the Urumiyeh-Dokhtar Volcanic Belt (U-DVB) which is the largest volcanic belt in Central Iran. These granitoids intrude Eocene volcano-sedimentary rocks and range from gabbrodiorites to granites, with dominance of diorites and tonalites. The mineral composition of the most felsic rocks is characterized by the abundance of Na-plagioclase, quartz, alkali feldspar and biotite (and hornblende, in granodiorites and tonalites). In dioritic and gabbroic rocks, plagioclase (Ca-rich, in the most mafic lithologies), hornblende, biotite and clinopyroxene are the most common minerals, sometimes accompanied by orthopyroxene. Two kind of enclaves have been identified within the intrusive rocks: some display the same features of the andesitic country volcanic rocks, and therefore, are interpreted as xenoliths; others have mineral assemblages similar to those of the enclosing granitoid but with larger proportions of mafic minerals, which suggests that they can represent disrupted portions of sectors of the magma chamber where preferential settling of heavy minerals took place. Major element geochemical data show that the Lazelar granitoids are mostly metaluminous, although the most felsic members (granites) attain slightly peraluminous compositions, with A/CNK varying from 0.85 to 1.03. Harker diagrams show, in general, good linear correlations that agree with a genetic relationship between the different granitoids, through fractional crystallization of plagioclase, pyroxene, amphibole, oxide minerals and apatite. In primitive mantle-normalized trace element spiderdiagrams, the analysed samples display strong enrichment in LILE compared to HFSE (15.78≤ RbN/YN ≤ 81.96), accompanied by negative anomalies of Nb, Ta and Ti. REE chondrite-normalized plots show moderate LREE enrichment (3.32 ≤ LaN/LuN ≤ 6.36) and slight to strong negative Eu anomalies (0.46 ≤ Eu/Eu* ≤ 0.92). In conclusion, the petrographical and geochemical features show that the Lalezar intrusives fit into I-type granitoids, belong to the calc-alkaline series and probably have been generated in a continental arc setting, which agrees with models previously presented to the U-DVB

    Oral consumption of α-linolenic acid increases serum BDNF levels in healthy adult humans

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    Background aims: Dietary omega-6 and omega-3 fatty acids have remarkable impacts on the levels of DHA in the brain and retina. Low levels of DHA in plasma and blood hamper visual and neural development in children and cause dementia and cognitive decline in adults. The level of brain-derived neurotrophic factors (BDNF) changes with dietary omega-3 fatty acid intake. BDNF is known for its effects on promoting neurogenesis and neuronal survival. Methods: In this study, we examined the effect of the oral consumption of α-Linolenic acid (ALA) on blood levels of BDNF and Malondialdehyde (MDA) in healthy adult humans. 30 healthy volunteers, 15 men and 15 women, were selected randomly. Each individual served as his or her own control. Before consuming the Flaxseed oil capsules, 5cc blood from each individual was sampled in order to measure the plasma levels of BDNF and MDA as baseline controls. During the experiment, each individual was given 3 oral capsules of flaxseed oil, containing 500mg of alpha linolenic acid, daily for one week. Then, plasma levels of BDNF and MDA were tested. Results: The plasma levels of BDNF and MDA significantly (P < 0.05) increased in individuals who received the oral capsules of ALA. Plasma levels of BDNF increased more in the women in comparison with the men. Conclusion: ALA treatment could be a feasible approach to reduce size of infarcts in stroke patients. Thus, ALA could be used in adjunction with routine stroke therapies to minimize brain lesions caused by stroke. © 2015 Hadjighassem et al.; licensee BioMed Central

    Confidence Prediction from EEG Recordings in a Multisensory Environment

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    This paper investigates the possibility of decoding decision confidence from electroencephalographic (EEG) brain activity of human subjects during a multisensory decision-making task. In recent research we have shown that decision confidence correlates could be extracted from EEG recordings during visual or auditory tasks. Here we extend these initial findings by (a) predicting the confidence in the decision from EEG recordings alone, and (b) investigating the impact of multisensory cues on decision-making behavioral data. Our results obtained from 12 participants recorded at two different sites show that the decision confidence could be predicted from EEG recordings on a single-trial basis with a mean absolute error of 0.226. Moreover, the presence of a multisensory cue did not improve the performance of the participants, but rather distracted them from the main task. Overall, these results may inform the development of cognitive systems that could monitor and alert users when they are not confident about their decisions

    The extracellular vesicles-derived from mesenchymal stromal cells: A new therapeutic option in regenerative medicine

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    ABSTRACT Mesenchymal stem cells (MSCs) are adult multipotent cells that due to their ability to homing to damaged tissues and differentiate into specialized cells, are remarkable cells in the field of regenerative medicine. It's suggested that the predominant mechanism of MSCs in tissue repair might be related to their paracrine activity. The utilization of MSCs for tissue repair is initially based on the differentiation ability of these cells; however now it has been revealed that only a small fraction of the transplanted MSCs actually fuse and survive in host tissues. Indeed, MSCs supply the microenvironment with the secretion of soluble trophic factors, survival signals and the release of extracellular vesicles (EVs) such as exosome. Also, the paracrine activity of EVs could mediate the cellular communication to induce cell- differentiation/self-renewal. Recent findings suggest that EVs released by MSCs may also be critical in the physiological function of these cells. This review provides an overview of MSC-derived extracellular vesicles as a hopeful opportunity to advance novel cell-free therapy strategies that might prevail over the obstacles and risks associated with the use of native or engineered stem cells. EVs are very stable; they can pass the biological barriers without rejection and can shuttle bioactive molecules from one cell to another, causing the exchange of genetic information and reprogramming of the recipient cells. Moreover, extracellular vesicles may provide therapeutic cargo for a wide range of diseases and cancer therapy. Key Words: Mesenchymal Stem Cells, Extracellular vesicles, Exosome, Regenerative medicine

    Chemical and enzymatic synthesis of the alginate sugar nucleotide building block: GDP-d-mannuronic acid

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    Highlights Sugarnucleotide synthesis. Chemical and enzymatic access to GDP-d-ManA. Evaluation of protected and free uronate 1-phosphates for pyrophosphorylation
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