Search results for "efficiency"
showing 10 items of 1430 documents
A methodology for the semi-automatic generation of analytical models in manufacturing
2018
International audience; Advanced analytics can enable manufacturing engineers to improve product quality and achieve equipment and resource efficiency gains using large amounts of data collected during manufacturing. Manufacturing engineers, however, often lack the expertise to apply advanced analytics, relying instead on frequent consultations with data scientists. Furthermore, collaborations between manufacturing engineers and data scientists have resulted in highly specialized applications that are not relevant to broader use cases. The manufacturing industry can benefit from the techniques applied in these collaborations if they can be generalized for a wide range of manufacturing probl…
Electrical and photovoltaic properties of indium‐tin‐oxide/p‐InSe/Au solar cells
1987
Conditions for efficiency improvement and optimization in indium‐tin‐oxide/p‐indium‐selenide solar cells are discussed in this paper. This aim is achieved by using low‐resistivity p‐indium‐selenide and by incorporating a back‐surface‐field contact. This contact is insured by a p‐indium selenide/gold barrier whose rectifying behavior is explained through the complex impurity structure of p‐indium‐selenide. Electrical and photovoltaic properties of the cells are also reported. The efficiency parameters under AM1 simulated conditions have been improved up to 32 mA/cm2 for the short‐circuit current density, 0.58 V for the open‐circuit voltage, and 0.63 for the filling factor. As a result, solar…
Joint Spectral and Energy Efficiency Optimization for Downlink NOMA Networks
2020
Non-orthogonal multiple access (NOMA) holds the promise to be a key enabler of 5G communication. However, the existing design of NOMA systems must be optimized to achieve maximum rate while using minimum transmit power. To do so, this paper provides a novel technique based on multi-objective optimization to efficiently allocate resources in the multi-user NOMA systems supporting downlink transmission. Specifically, our unique optimization technique jointly improves spectrum and energy efficiency while satisfying the constraints on users quality of services (QoS) requirements, transmit power budget and successive interference cancellation. We first formulate a joint problem for spectrum and …
Agents Displacement in Arbitrary Geometrical Spaces: An Evolutionary Computation based Approach
2015
In many different social contexts, communication allows a collective intelligence to emerge. However, a correct way of exchanging information usually requires determined topological configurations of the agents involved in the process. Such a configuration should take into account several parameters, e.g. agents positioning, their proximity and time efficiency of communication. Our aim is to present an algorithm, based on evolutionary programming, which optimizes agents placement on arbitrarily shaped areas. In order to show its ability to deal with arbitrary bi-dimensional topologies, this algorithm has been tested on a set of differently shaped areas that present concavities, convexities …
Dumbbell-Shaped Dinuclear Iridium Complexes and Their Application to Light-Emitting Electrochemical Cells
2010
A novel family of dumbbell- shaped dinuclear complexes in which an oligophenyleneethynylene spacer is linked to two heteroleptic iridiumA complexes is presented. The synthesis, as well as the electrochemical and pho- tophysical characterization of the new complexes, is reported. The experimen- tal results are interpreted with the help of density functional theory calcula- tions. From these studies we conclude that the lowest triplet excited state cor- responds to a 3 p-p* state located on the conjugated spacer. The presence of this state below the 3 MLCT/ 3 LLCT emitting states of the end-capping Ir III complexes explains the low quantum yields observed for the dinuclear com- plexes (one or…
A simple method for measuring OLEDs efficiency
2015
External quantum efficiency (EQE) of organic light emitting diodes (OLEDs) is among the most important parameters for devices assessment and for comparing OLEDs performance. The EQE is the ratio of the total number of photons emitted by the OLED in all directions to the number of electrons injected.
Exergetic and exergoeconomic analysis of a novel hybrid solar-geothermal polygeneration system producing energy and water
2016
Abstract A dynamic simulation model of a novel solar–geothermal polygeneration system and the related exergetic and exergoeconomic analyses are presented in this paper. The plant is designed in order to supply electrical, thermal and cooling energy and fresh water for a small community, connected to a district heating and cooling network. The hybrid system is equipped with an Organic Rankine Cycle fueled by medium-enthalpy geothermal energy and by a Parabolic Trough Collector solar field. Geothermal brine is also used for space heating and cooling purposes. Finally, geothermal fluid supplies heat to a Multi-Effect Distillation unit, producing also desalinized water from seawater. Dynamic si…
Efficiency enhancement of organic light emitting diodes by NaOH surface treatment of the ITO anode
2009
Abstract Organic light emitting diodes (OLEDs) based on tris-(8-idroxyquinoline)aluminum (Alq 3 ) with enhanced efficiency are reported here. This is obtained by improving the charge carrier balance, through a preliminary NaOH surface treatment of the indium tin oxide (ITO) anode, in order to decrease its work function and, consequently, reduce the hole injection. The obtained devices exhibit a 1.36% external quantum efficiency and a 1.2 lm/W power efficiency at a current density of 60 mA/cm 2 . These values are more than double as compared with those of identical reference devices fabricated without the preliminary NaOH surface treatment.
Photoelectrical properties of thin films of DMABI derivatives
2011
Organic thin films with semiconducting properties have been intensively studied in nowadays due to very promising applications in organic electronics, for example, organic photovoltaic. Among organic semiconductors, group of indandiones with their photoelectrical properties, thermal and chemical stability are good candidates for use in design of novel molecular electronic devices. We have investigated photoconductivity quantum efficiency and its spectral dependence of two dimetilaminobenzylidene-1,3-indandione derivatives. Values of the photoconductivity threshold energy and optical energy gap are obtained. These results are compared with calculated transfer energy gap estimated according t…
Bis(N-naphthyl-N-phenylamino)benzophenones as exciton-modulating materials for white TADF OLEDs with separated charge and exciton recombination zones
2022
Abstract Organic semiconductors were employed as exciton modulators, blue emitters, hole-transporting materials and hosts with resonant-appropriate singlet and triplet energies for efficient and stable white organic light emitting diodes (OLEDs). Two 4,4'-bis(N-naphthyl-N-phenylamino)benzophenones were synthesized using isomeric N-naphthyl-N-phenylamines as the donors and benzophenone as the acceptor moiety. Molecular design of new compounds allowed to obtain required combination of properties, i.e. blue prompt fluorescence in solid state with singlet energies close to those of the selected blue emitter exhibiting thermally activated delayed fluorescence (TADF), low triplet energies of 2.32…