scholarly journals Characterization of energy conversion of multiferroic PFN and PFN:Mn

2013 ◽  
Vol 7 (4) ◽  
pp. 167-173 ◽  
Author(s):  
Lucjan Kozielski ◽  
Dariusz Bochenek
Keyword(s):  
Energy Conversion ◽  
High Speed ◽  
Ferroelectric Properties ◽  
Pyrochlore Phase ◽  
Energy Conversion Efficiency ◽  
Modern Technology ◽  
Point Of View ◽  
Synthesis Process ◽  
Multiferroic Materials

Characterization of energy conversion of multiferroic materials is concerned with multifunctional properties of materials, a topic that is fascinating from the scientific point of view and important for the modern technology. The complex characterization of multiferroic structures suffers at present from lack of a systematic experimental approach and deficiency of multifunctional magnetoelectric properties testing capabilities. Compactness and high frequency energy conversion capacity are the main reasons of invention and improvement of sophisticated materials which are prepared for high-speed computer memories and broadband transducer devices. As a consequence, one can easily notice an intense search for new materials for generation, transformation and amplification of magnetic and electric energies. In this scenario, the combination of excellent piezoelectric and magnetic properties makes lead iron niobate Pb(Fe1/2Nb1/2)O3 (PFN) an attractive host material for application in integrated magnetoelectric energy conversion applications. PFN multiferroic materials are attractive for commercial electroceramics due to high value of dielectric permittivity and magnetoelectric coefficients as well as relatively easy synthesis process. However, synthesis of PFN ceramics is mostly connected with formation of the secondary unwanted pyrochlore phase associated with dramatic decrease of ferroelectric properties. The authors have successfully reduced this negative phenomenon by Mn doping and finally present high piezoelectric and magnetoelectric energy conversion efficiency in fabricated PMFN ceramics.

scholarly journals Neuromorphic van der Waals crystals for substantial energy generation

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Sungsoon Kim ◽  
Sangjin Choi ◽  
Hae Gon Lee ◽  
Dana Jin ◽  
Gwangmook Kim ◽  
...  
Keyword(s):  
Energy Conversion ◽  
High Speed ◽  
Rational Design ◽  
Large Scale ◽  
Ion Selectivity ◽  
Diffusion Flux ◽  
Van Der Waals ◽  
Energy Conversion Efficiency ◽  
Ion Diffusion ◽  
Nanofluidic Channels

AbstractControlling ion transport in nanofluidics is fundamental to water purification, bio-sensing, energy storage, energy conversion, and numerous other applications. For any of these, it is essential to design nanofluidic channels that are stable in the liquid phase and enable specific ions to pass. A human neuron is one such system, where electrical signals are transmitted by cation transport for high-speed communication related to neuromorphic computing. Here, we present a concept of neuro-inspired energy harvesting that uses confined van der Waals crystal and demonstrate a method to maximise the ion diffusion flux to generate an electromotive force. The confined nanochannel is robust in liquids as in neuron cells, enabling steady-state ion diffusion for hundred of hours and exhibiting ion selectivity of 95.8%, energy conversion efficiency of 41.4%, and power density of 5.26 W/m2. This fundamental understanding and rational design strategy can enable previously unrealisable applications of passive-type large-scale power generation.

Experimental Characterization of a Meso-Scale Combustion Driven Actuator Designed for High Efficiency

2015 ◽  
Author(s):  
Alexandre Bélanger Desbiens ◽  
Jean-Sébastien Plante ◽  
Patrice Masson
Keyword(s):  
Power Systems ◽  
Energy Conversion ◽  
Combustion Chamber ◽  
Conversion Efficiency ◽  
Compression Ratio ◽  
Equivalence Ratio ◽  
Energy Conversion Efficiency ◽  
Experimental Characterization ◽  
Meso Scale

Meso-scale power systems (10 W to 1000 W) are needed to power untethered mobile robots and assisting devices such as powered exoskeletons. Air-breathing combustion driven actuators, used in a direct acting manner, can be used for such applications and take advantage of the high power density of fluidic actuators and the high energy density of chemical fuels. However, fuel-to-mechanical energy conversion efficiency is critical to make such chemical systems viable over electrical systems. This paper presents the efficiency-based design and experimental characterization of two combustion driven actuators intended to reach high specific power and specific energy. First, efficiency oriented design principles are derived from internal combustion engine theory: (1) an ideal-cycle thermodynamic model of a generic constant volume combustion system suggests that compression ratio and the expansion/compression ratio should both be maximized, and (2) the practical effects of heat, mass and friction losses as well as fuel choice in a small scale combustion chamber context are discussed. Second, two simplified prototypes are built and tested. The first prototype uses a rolling diaphragm seal to limit the effect of mass and friction losses. The second prototype consists of a standard air cylinder that minimizes heat losses by reducing the surface-to-volume ratio of the combustion chamber. Hydrogen is selected as fuel because it allows lean combustion which limits the effect of heat loss with low combustion temperatures. Compression ratio and equivalence ratio are varied experimentally to evaluate their effect on efficiency. Experimental results demonstrate an energy conversion efficiency of 15.3% at a compression ratio of 4.15 and a low equivalence ratio of 0.3. Ragone analysis of relevant meso-scale power systems for mobile robotic suggest that, with proper optimization and system integration, combustion driven power systems can become a viable solution for lightweight and long range meso-scale robotic applications.

scholarly journals Investigation on Electromagnetic Models of High-Speed Solenoid Valve for Common Rail Injector

2017 ◽  
Vol 2017 ◽  
pp. 1-10 ◽  
Author(s):  
Jianhui Zhao ◽  
Liyun Fan ◽  
Peng Liu ◽  
Leonid Grekhov ◽  
Xiuzhen Ma ◽  
...  
Keyword(s):  
Energy Conversion ◽  
Magnetic Materials ◽  
Conversion Efficiency ◽  
High Speed ◽  
Energy Conversion Efficiency ◽  
Solenoid Valve ◽  
Electromagnetic Energy ◽  
Soft Magnetic Materials ◽  
Soft Magnetic ◽  
Drive Current

A novel formula easily applied with high precision is proposed in this paper to fit the B-H curve of soft magnetic materials, and it is validated by comparison with predicted and experimental results. It can accurately describe the nonlinear magnetization process and magnetic saturation characteristics of soft magnetic materials. Based on the electromagnetic transient coupling principle, an electromagnetic mathematical model of a high-speed solenoid valve (HSV) is developed in Fortran language that takes the saturation phenomena of the electromagnetic force into consideration. The accuracy of the model is validated by the comparison of the simulated and experimental static electromagnetic forces. Through experiment, it is concluded that the increase of the drive current is conducive to improving the electromagnetic energy conversion efficiency of the HSV at a low drive current, but it has little effect at a high drive current. Through simulation, it is discovered that the electromagnetic energy conversion characteristics of the HSV are affected by the drive current and the total reluctance, consisting of the gap reluctance and the reluctance of the iron core and armature soft magnetic materials. These two influence factors, within the scope of the different drive currents, have different contribution rates to the electromagnetic energy conversion efficiency.

scholarly journals Analysis of Dynamic Characteristics and Power Losses of High Speed on/off Valve with Pre-Existing Control Algorithm

Energies ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4901
Author(s):  
Qi Zhong ◽  
Xiele Wang ◽  
Geng Xie ◽  
Huayong Yang ◽  
Cheng Yu ◽  
...  
Keyword(s):  
Energy Conversion ◽  
Dynamic Characteristics ◽  
Hydraulic System ◽  
High Speed ◽  
Control Algorithm ◽  
Energy Conversion Efficiency ◽  
Power Losses ◽  
Closing Time ◽  
Energy Characteristics ◽  
Overall Performance

A high-speed on/off valve (HSV) is generally the core component of a digital hydraulic transmission system. Therefore, its dynamic characteristics often restrict the overall performance of the digital hydraulic system. Most of the current studies focus on the optimization on the dynamic characteristics or the energy characteristics, few studies have comprehensively considered the two characteristics of the valve together. In this paper, a pre-existing control algorithm (PECA) is proposed to improve the dynamic characteristics of the HSV, and simultaneously optimize the power losses of the HSV to improve its energy conversion efficiency. The results show that, compared with the traditional single-voltage driven strategy, the opening time of the PECA decreases by 29.4%, the closing time decreases by 59.6%, and the energy conversion rate increases by 7.9%.

Characterization of a monolayer graphitic structure

1994 ◽  
Vol 52 ◽  
pp. 760-761
Author(s):  
X. Lin ◽  
X. K. Wang ◽  
V. P. Dravid ◽  
J. B. Ketterson ◽  
R. P. H. Chang
Keyword(s):  
Three Dimensional ◽  
Single Layer ◽  
Synthesis Process ◽  
Graphitic Structure ◽  
Positive Gaussian Curvature ◽  
Graphitic Sheet ◽  
Structural And Electronic Properties ◽  
New Material ◽  
Hexagonal Network

For small curvatures of a graphitic sheet, carbon atoms can maintain their preferred sp2 bonding while allowing the sheet to have various three-dimensional geometries, which may have exotic structural and electronic properties. In addition the fivefold rings will lead to a positive Gaussian curvature in the hexagonal network, and the sevenfold rings cause a negative one. By combining these sevenfold and fivefold rings with sixfold rings, it is possible to construct complicated carbon sp2 networks. Because it is much easier to introduce pentagons and heptagons into the single-layer hexagonal network than into the multilayer network, the complicated morphologies would be more common in the single-layer graphite structures. In this contribution, we report the observation and characterization of a new material of monolayer graphitic structure by electron diffraction, HREM, EELS.The synthesis process used in this study is reported early. We utilized a composite anode of graphite and copper for arc evaporation in helium.

The Analyses of Learning Strategies in English as a Second Language: Theoretical Classification and Measurement Test

2020 ◽  
Vol 4 (2) ◽  
pp. 118-129
Author(s):  
Asti Gumartifa ◽  
◽  
Indah Windra Dwie Agustiani
Keyword(s):  
Language Learning ◽  
Learning Outcomes ◽  
Learning Strategies ◽  
Learning Process ◽  
English Learners ◽  
English Language ◽  
Point Of View ◽  
Effective Learning ◽  
The Impact

Gaining English language learning effectively has been discussed all years long. Similarly, Learners have various troubles outcomes in the learning process. Creating a joyful and comfortable situation must be considered by learners. Thus, the implementation of effective learning strategies is certainly necessary for English learners. This descriptive study has two purposes: first, to introduce the classification and characterization of learning strategies such as; memory, cognitive, metacognitive, compensation, social, and affective strategies that are used by learners in the classroom and second, it provides some questionnaires item based on Strategy of Inventory for Language Learning (SILL) version 5.0 that can be used to examine the frequency of students’ learning strategies in the learning process. The summary of this study explains and discusses the researchers’ point of view on the impact of learning outcomes by learning strategies used. Finally, utilizing appropriate learning strategies are certainly beneficial for both teachers and learners to achieve the learning target effectively.

The Algorithm of Characterization of an Action as a Jointly Committed Crime

2018 ◽  
pp. 37-44
Keyword(s):  
Criminal Code ◽  
Point Of View

The article discusses a sequence of activities to identify a crime as jointly committed. The requirements to the algorithm of such activities are formulated. Programme-based and targeted methods applied by the authors allowed detecting a range of stages of the algorithm. The first four stages aim at defining mandatory elements of a crime allowing to characterize it as a jointly committed action. The rest of the stages focus on identifying a type of criminal complicity. In the article, each stage is described. It is emphasized that in each stage there is a special objective. At the same time, all these stages, taken together, constitute a separate module of the program of criminal characterization of an action. From the authors’ point of view, algorithms are necessary not only for detection of crimes and their criminal characterization, but also for answering the question on existence of criminal complicity in each case. Also the authors give their opinions on interpretation of criminal complicity as a legal category. In particular, it is emphasized that not all of crimes merely committed with participation of two or more persons should be understood as jointly committed. It is joint participation that makes a crime jointly committed. Various forms of criminal complicity and types of co-offenders are considered in the article as well. In various crimes, criminal complicity manifests itself differently. Therefore the proposed algorithm can be applied only after identification a specific article of the Russian Criminal Code stipulating the responsibility for the crime committed.

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