Search results for "efficiency"

showing 10 items of 1430 documents

Seagrass ecosystem response to long-term high CO2 in a Mediterranean volcanic vent

2014

We examined the long-term effect of naturally acidified water on a Cymodocea nodosa meadow growing at a shallow volcanic CO2 vent in Vulcano Island (Italy). Seagrass and adjacent unvegetated habitats growing at a low pH station (pH = 7.65 ± 0.02) were compared with corresponding habitats at a control station (pH = 8.01 ± 0.01). Density and biomass showed a clear decreasing trend at the low pH station and the below- to above-ground biomass ratio was more than 10 times lower compared to the control. C content and delta 13C of leaves and epiphytes were significantly lower at the low pH station. Photosynthetic activity of C. nodosa was stimulated by low pH as seen by the significant increase in…

Ocean Acidification International Coordination Centre (OA-ICC)TemperateSalinityChlorophyll ainorganicAlkalinityLight saturation point standard errorPhotosynthetic quantum efficiencyMediterranean Sea Acidification in a Changing Climate MedSeATemperature waterCarbon inorganic dissolvedCalculated using seacarb after Nisumaa et al 2010IrradianceRespiration rate carbonAragonite saturation stateBiomassAlkalinity totalIrradiance standard errortotalCO2 ventCymodocea nodosapHRespirationEpiphytes loadMaximum photochemical quantum yield of photosystem II standard errorNet community production of carbonTemperaturePartial pressure of carbon dioxide (water) at sea surface temperature (wet air) standard errordissolvedRespiration rate carbon standard errorCarbonate ionMaximum photochemical quantum yield of photosystem IIPartial pressure of carbon dioxide (water) at sea surface temperature (wet air)Net community production of carbon standard errorIlluminance standard errorSoft bottom communitystandard errorCarbon inorganic dissolved standard errorRespiration rateElectron transport rate standard errorEarth System Researchδ13CPhotosynthetic quantum efficiency standard errorField observationChlorophyll a standard errorGross primary production of carbonBiomass standard errorCalcium carbonatePotentiometric titrationCalcite saturation stateShoot densityPotentiometricwaterIlluminanceOxygen standard errorBenthosAlkalinity total standard errorMediterranean Sea Acidification in a Changing Climate (MedSeA)Electron transport rateLight saturation pointOcean Acidification International Coordination Centre OA ICCMediterranean SeaGross primary production of carbon standard errorBicarbonate ionSoft-bottom communityδ13C standard errorTemperature water standard errorCalculated using seacarb after Nisumaa et al. (2010)Primary production PhotosynthesisSpeciespH standard errorCarbonate system computation flagloadPrimary production/PhotosynthesisFugacity of carbon dioxide (water) at sea surface temperature (wet air)CarbonBiomass/Abundance/Elemental compositionTreatmentEpiphytes load standard errorOxygenPartial pressure of carbon dioxide water at sea surface temperature wet airEpiphytes loadCarbon dioxideCarbon standard errorEntire communityFugacity of carbon dioxide water at sea surface temperature wet airGroupBiomass Abundance Elemental compositionCoast and continental shelfEpiphytesShoot density standard errorCalcium carbonate standard error
researchProduct

Empirical BAC factors method application to two real case studies in South Italy

2021

Abstract The application of Building Automation and Control (BAC) systems has many advantages. One of these is the reduction of the end-user electricity consumption and, if applied to lighting systems, the achievement of well-acknowledged benefits from daylight, such as productivity, health, visual comfort and well-being. Concerning the first aspect, the international Standard EN 15232 proposes the so-called BAC Factors (BF) method to assess the impact of BAC systems on the final energy consumption. The method provides a simplified estimation of the energy savings due to automation in buildings and questions arise on its applicability in some situations. For this reason, the authors have ca…

Operations researchComputer scienceIndustrial and Manufacturing EngineeringBAC factorsDaylight linked control systemsDaylightElectrical and Electronic EngineeringProductivityBAC factors Daylight linked control systems Energy efficiency in buildings Lighting Lighting controlsLightingEnergy efficiency in buildings Lighting controls BAC factors Lighting Daylight linked control systemsCivil and Structural EngineeringBuilding automationConsumption (economics)Settore ING-IND/11 - Fisica Tecnica AmbientaleLighting controlsEnergy efficiency in buildingsbusiness.industryMechanical EngineeringInternational standardBuilding and ConstructionPollutionAutomationSettore ING-IND/33 - Sistemi Elettrici Per L'EnergiaGeneral EnergyControl systemElectricitybusinessEnergy
researchProduct

On the importance of perspective and flexibility for efficiency measurement: effects on the ranking of decision-making units

2017

[EN] The efficiency of a firm can be assessed from several perspectives and using a variety of methodologies. Data envelopment analysis (DEA) is one of the most commonly used methodologies. Conventional DEA analyses or models allow one to classify decision-making units (DMUs) into efficient and inefficient ones based on their efficiency scores, which could also be used for ranking DMUs; however, such rankings generally show many ties. Super-efficiency DEA analyses have been proposed to address the tie issue. On the other hand, conventional DEA analyses only take account of a single perspective in estimating efficiency scores. Cross-efficiency DEA analyses provide an alternative that takes a…

Operations researchStrategy and Management0211 other engineering and technologies02 engineering and technologyManagement Science and Operations Researchcomputer.software_genreFuzzy logicManagement Information SystemsDEAOrder (exchange)Robustness (computer science)0202 electrical engineering electronic engineering information engineeringEconomicsData envelopment analysisTOPSISMarketingFlexibility (engineering)021103 operations researchTOPSISVariety (cybernetics)Fuzzy logicRanking methodsRankingCross-efficiency020201 artificial intelligence & image processingData miningMATEMATICA APLICADAcomputerJournal of the Operational Research Society
researchProduct

Backward frequency doubling of near infrared picosecond pulses.

2014

We report on backward second-harmonic generation using ps laser pulses in congruent lithium niobate with 3.2 µm periodic poling. Three resonant peaks were measured between 1530 and 1730 nm, corresponding to 16th, 17th and 18th quasi-phase-matching orders in the backward configuration, with a conversion efficiency of 4.75 x 10(-5%)/W for the 16th order. We could also discriminate the contributions from inverted domains randomized in duty-cycle.

Optical amplifierMaterials sciencebusiness.industryLithium niobateEnergy conversion efficiencyNonlinear OpticSecond-harmonic generationSettore ING-INF/02 - Campi ElettromagneticiLaserHarmonic generation and mixingSettore ING-INF/01 - ElettronicaAtomic and Molecular Physics and Opticslaw.inventionchemistry.chemical_compoundOpticschemistryPeriodic polinglawParametric ProcessePicosecondPicosecond phenomenabusinessPhase conjugationOptics express
researchProduct

Diode-pumped bulk Er:Yb:Glass 1.54μm pulsed laser with 1.2J output and 25% optical efficiency

2002

We report a pulsed transversely diode-pumped compact Er:Yb:Glass laser of uncomplicated design, delivering output energy of approx. 1.2J in free-running operation and 25% optical slope efficiency.

Optical efficiencyPulsed laserGlass laserMaterials sciencebusiness.industrySlope efficiencyDiode-pumped solid-state laserPhysics::OpticsOptoelectronicsLaser pumpingbusinessTunable laserDiodeAdvanced Solid-State Lasers
researchProduct

Design of Er3+-doped chalcogenide glass laser for MID-IR application

2009

Abstract The feasibility of a photonic crystal fiber laser (PCF laser), made of a novel Er 3+ -doped chalcogenide glass and operating at the wavelength λ s  = 4.5 μm is investigated. The design is performed on the basis of spectroscopic and optical parameters measured on a fabricated Er 3+ -doped Ga 5 Ge 20 Sb 10 S 65 chalcogenide bulk sample. The simulations have been performed by employing a home made numerical code that solves the multilevel rate equations and the power propagation equations via a Runge-Kutta iterative method. The numerical results indicate that a laser exhibiting slope efficiency close to the maximum theoretical one and a wide tunability in the wavelengths range where t…

Optical fiberMaterials scienceChalcogenideInfrared fibersPhysics::OpticsChalcogenide glass02 engineering and technology01 natural sciences7. Clean energylaw.invention010309 opticschemistry.chemical_compoundOpticslaw0103 physical sciencesMaterials ChemistryOptical fibersChalcogenides; Infrared fibers; Lasers; Optical fibersbusiness.industryLasersSlope efficiencyDoping[CHIM.MATE]Chemical Sciences/Material chemistryRate equation021001 nanoscience & nanotechnologyCondensed Matter PhysicsLaserElectronic Optical and Magnetic Materialschemistry[ CHIM.MATE ] Chemical Sciences/Material chemistryCeramics and Composites0210 nano-technologybusinessChalcogenidesPhotonic-crystal fiberJournal of Non-Crystalline Solids
researchProduct

Comparative laser study of Nd:KGW and Nd:YAG near 1.3 μm

1997

A comparative study of Nd:KGW and Nd:YAG laser crystals pumped by flashlamp has been conducted near 1.3 μm with output energy up to 1 J and at a repetition rate up to 50 Hz. An average power of 23 W for KGW in free-running mode was achieved with a total efficiency better than 2.8 % for the Nd:KGW and 1.8 % for the Nd:YAG.

OpticsMaterials sciencePhysics and Astronomy (miscellaneous)business.industrylawTotal efficiencyGeneral EngineeringGeneral Physics and AstronomybusinessLaserlaw.inventionApplied Physics B: Lasers and Optics
researchProduct

Performance improvement of a novel combined water turbine

2020

Abstract Nowadays, industrials and researchers are looking for renewable energy resources due to the increase of energy demand. Recently, the ability of combined turbines in harnessing energy from water current has increased their renewed interest. However, there still exist a big knowledge gap to select the optimal design of these turbines. In this paper, systematic studies of stand-alone helical Savonius and delta bladed Darrieus turbines were carried out using experimental methods as a precursor to analyze their roles in hybrid configuration. By varying the attachment angle, two hybrid configurations were tested experimentally. Using the optimal attachment angle, six hybrid configuration…

Optimal designMaximum power principleComputer scienceWater turbine020209 energyEnergy Engineering and Power TechnologyMechanical engineeringEfficiency02 engineering and technologyTurbineSettore ICAR/01 - Idraulica020401 chemical engineering0202 electrical engineering electronic engineering information engineering0204 chemical engineeringCommercial softwareDelta bladeRenewable Energy Sustainability and the Environmentbusiness.industryRenewable energyPower (physics)Fuel TechnologyNuclear Energy and EngineeringAttachment anglePowerPerformance improvementHybrid turbinebusinessFlow characteristicEnergy Conversion and Management
researchProduct

Distributed Resource Allocation for Energy Efficiency in OFDMA Multicell Networks with Wireless Power Transfer

2019

In this paper, an energy-efficient resource allocation problem is investigated for the wireless power transfer (WPT)-enabled OFDMA multicell networks. In the considered system, multiple base stations (BSs) with a large number of antennas are responsible to provide WPT in the downlink, and the users can recycle and utilize the received energy for uplink data transmission. The role of BS is to execute WPT; thus, there are no data transmissions in the downlink. A time-division protocol is considered to divide the time of downlink WPT and uplink wireless information transfer into separate time slots. With the objective to improve the energy efficiency, we propose the time, subcarrier, and power…

Optimization problemComputer Networks and CommunicationsComputer sciencesubcarrier allocationenergiatehokkuusDistributed computingwireless power transfer02 engineering and technologyData_CODINGANDINFORMATIONTHEORYSubcarrierNonlinear programmingantenna selectionBase stationTelecommunications link0202 electrical engineering electronic engineering information engineeringComputer Science::Networking and Internet ArchitectureWirelessElectrical and Electronic Engineeringvoimansiirtoenergy efficiencyComputer Science::Information Theoryta213business.industryComputerSystemsOrganization_COMPUTER-COMMUNICATIONNETWORKStime allocation020206 networking & telecommunicationspower allocationChannel state informationResource allocationbusinesslangattomat verkotEfficient energy use
researchProduct

Energy efficient resource allocation for secure OFDMA relay systems with eavesdropper

2016

In this paper, we address the energy efficient resource allocation problem for a secure orthogonal frequency division multiple access (OFDMA) relay system. In particular, we consider there is a eavesdropper near the base station (BS) which tries to overtake the information sent by BS. We formulate the joint optimization problem with the objective to optimize the energy efficiency of the considered system by considering subcarrier pairing, secret data rate and power allocation. In addition, the system can assign different priority to different users such that the security of information transmission can be guaranteed. The proposed iterative algorithm not only maximizes the system energy effi…

Optimization problemComputer scienceOrthogonal frequency-division multiplexingOrthogonal frequency-division multiple accessThroughput02 engineering and technologyrelaysecure communicationslaw.inventionOFDMABase station0203 mechanical engineeringRelaylawartificial noise0202 electrical engineering electronic engineering information engineeringResource managementenergy efficiencyta113business.industryQuality of servicesubcarrier pair020302 automobile design & engineering020206 networking & telecommunicationsbusinessEfficient energy useComputer network2016 IEEE International Conference on Communications (ICC)
researchProduct