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Muratov, D. G., L. V. Kozhitov, A. V. Popkova, E. Yu Korovin, E. V. Yakushko i M. R. Bakirov. "Study of the radar absorption of metal-carbon nanocomposites (review)". Industrial laboratory. Diagnostics of materials 89, nr 1 (21.01.2023): 35–45. http://dx.doi.org/10.26896/1028-6861-2023-89-1-35-45.
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Development of the technology for the synthesis of magnetic nanoparticles of metals and alloys has opened up the possibility of their use in the field of radar-absorbing materials (RAM). The results of studying the properties of nanocomposites, method for the synthesis of metal-carbon nanocomposites by pyrolysis using infrared heating are reviewed. The magnetic, electromagnetic, and radar-absorbing properties of the obtained nanocomposites depending on the synthesis temperature and metal concentration were studied. It is shown that the chosen metals, alloys (FeCo) and carbon material are effective for isolating magnetic nanoparticles when developing hybrid radar-absorbing composites. Moreover, methods for controlling the radar-absorbing properties of hybrid composites and the prospects for improving the impedance matching are considered. An analysis of the efficiency of absorption of electromagnetic radiation by FeCo/C nanocomposites synthesized by different methods is presented. The possibility of controlling the morphology and properties of metal-carbon nanocomposites using certain approaches to synthesis, varying the compositions of precursors, and the orientation of FeCo nanoparticles synthesized in the form of flakes in the composite has been revealed. The results of the study can be used to improve the technique of using FeCo/C nanocomposites obtained by pyrolysis of organometallic precursors based on polyacrylonitrile in the field of radar-absorbing materials.
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Salisu, Bashir. "CHARACTERIZATION OF HYBRID-FORMAMIDINIUM BISMUTH BROMIDE PEROVSKITE MATERIAL (FABi2Br9) SYNTHESIZED VIA GROWTH ASSISTED TECHNIQUE FOR SOLAR CELLS APPLICATION". FUDMA JOURNAL OF SCIENCES 5, nr 3 (2.11.2021): 169–76. http://dx.doi.org/10.33003/fjs-2021-0503-694.
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ABSTRACT
In the last decade, organic-inorganic perovskite solar cells (PSCs) have had tremendous success, raising their power conversion efficiency from 3.8% in 2009(T, A, K, & Y, 2009) to >25.6% (Li et al., 2021). Perovskite material is newly emergent, third-generation solar cells, it generally refers to any composite that has structure like that of calcium titanium oxide (CaTiO2). It has a general formula ABX3, where A refers to an organic compound, B is an inorganic and X represents the halides. In this research, a Hybrid-Formamidinium Bismuth Bromide Perovskite solar cell (FABi2Br9) was synthesized via a novel crystal growth process and subjected to characterization for determining its optoelectronic properties for solar cells application. The x-ray diffraction (XDR) results revealed the crystal hexagonal structure of FABi2Br9, the crystal sizes were obtained and it gives an excellent size (74nm) for light absorption material. The bandgap was determined using ultraviolet-visible spectroscopy (U.V vis) which was found to be 1.80eV which is within the required range for an absorbing layer in a solar cell architecture. Nuclear magnetic resonance (NMR) and was used to identify the organic content purity of the composite. In conclusion, FABi2Br9 was found to be pure with excellent optoelectronics properties that can readily be used as an absorbent layer in perovskite solar cells architecture
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Cantrell, Will, i George E. Ewing. "Attenuated (but Not Total) Internal Reflection FT-IR Spectroscopy of Thin Films". Applied Spectroscopy 56, nr 5 (maj 2002): 665–69. http://dx.doi.org/10.1366/0003702021955240.
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We present a spectroscopic technique that is a hybrid between reflection-absorption and attenuated total reflection (ATR) spectroscopy. The method, which we call attenuated internal reflection (AIR), is suitable for the investigation of thin film liquids on non-or weakly absorbing substrates. In AIR the interrogating infrared beam is not exposed to vapor that may be associated with the film, but unlike ATR there are few geometric constraints on the substrate. We show the theoretical basis for the method and results from experiments demonstrating its use.
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Mohamad, Barhm, Jalics Karoly, Andrei Zelentsov i Salah Amroune. "A hybrid method technique for design and optimization of Formula race car exhaust muffler". International Review of Applied Sciences and Engineering 11, nr 2 (sierpień 2020): 174–80. http://dx.doi.org/10.1556/1848.2020.20048.
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AbstractIn this work a multilevel Computational Fluid Dynamics (CFD) analysis has been applied for the design of a Formula race car exhaust muffler with improved characteristics of sound pressure level (SPL) and fluid dynamic response. The approaches developed and applied for the optimization process range from the 1D to fully 3D CFD simulation, exploring hybrid approaches based on the integration of a 1D model with 3D tools. Modern mufflers typically have a complex system of chambers and flow paths. There are a variety of sound damping and absorbing mechanisms working to quiet the sound flowing through a muffler and piping system. Two calculation methods were selected for this study. The muffler has a complex inner structure containing perforated pipe and fiber material. Computer-aided design (CAD) file of the muffler was established for developing Finite Element Analysis (FEA) model in AVL BOOST v2017 and another commercial advanced design software (SolidWorks 2017). FEA model was made to monitor the flow properties, pressure and velocity. After the model was verified, sensitivity studies of design parameters were performed to optimize the SPL of the muffler. The software analysis results are included in the paper. Recommendations are made for obtaining smoother SPL curves for various measurement methods.
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Tao, Chenglin, Zhao Wang, Zeliang Liu, Yuan Wang, Xin Zhou, Xi Liang i Huijian Li. "Crashworthiness of Additively Manufactured Lattice Reinforced Thin-Walled Tube Hybrid Structures". Aerospace 10, nr 6 (1.06.2023): 524. http://dx.doi.org/10.3390/aerospace10060524.
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In this paper, a new hybrid structure of body-centered cubic lattice-filled thin-walled tube is designed, and the hybrid structure specimens of one-piece printing and split-printing are prepared by laser melting technique. The deformation mode and energy absorption characteristics of the new hybrid structure are investigated by experiments and numerical simulations. Under axial compression, the one-piece printed hybrid structure forms more wrinkles with smaller wavelengths, and the specific energy absorption increases by 12.14% compared with the split-printed structure; under transverse compression, the one-piece printed structure does not show the separation of the thin-walled tube from the lattice, and the specific energy absorption increases by 134.83% compared with the split-printed structure. It is worth noting that the designed hybrid structure has a 112.60% (580.15%) increase in specific energy absorption under axial compression (under transverse compression) compared to the empty tube. The effects of wall thickness, lattice density, and loading rate on the crashworthiness of the hybrid structure were investigated using a validated finite element model. This paper provides a new idea for the preparation of lightweight and high-strength energy-absorbing structures.
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Huang, Shaowu, Gary Charles, Kai Xiao i Beomtaek Lee. "REDUCTION OF PCB PDN IMPEDANCE AND RADIATED EMISSIONS USING A HYBRID TECHNIQUE WITH ABSORBING MATERIALS AND DECOUPLING CAPACITORS". Progress In Electromagnetics Research B 77 (2017): 137–54. http://dx.doi.org/10.2528/pierb17041605.
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Dolci, Daiane Iglesia, Felipe A. G. Silva, Pedro S. Peixoto i Ernani V. Volpe. "Effectiveness and computational efficiency of absorbing boundary conditions for full-waveform inversion". Geoscientific Model Development 15, nr 14 (27.07.2022): 5857–81. http://dx.doi.org/10.5194/gmd-15-5857-2022.
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Abstract. Full-waveform inversion (FWI) is a high-resolution numerical technique for seismic waves used to estimate the physical characteristics of a subsurface region. The continuous problem involves solving an inverse problem on an infinite domain, which is impractical from a computational perspective. In limited area models, absorbing boundary conditions (ABCs) are usually imposed to avoid wave reflections. Several relevant ABCs have been proposed, with extensive literature on their effectiveness on the direct wave problem. Here, we investigate and compare the theoretical and computational characteristics of several ABCs in the full inverse problem. After a brief review of the most widely used ABCs, we derive their formulations in their respective adjoint problems. The different ABCs are implemented in a highly optimized domain-specific language (DSL) computational framework, Devito, which is primarily used for seismic modelling problems. We evaluate the effectiveness, computational efficiency, and memory requirements of the ABC methods, considering from simple models to realistic ones. Our findings reveal that, even though the popular perfectly matching layers (PMLs) are effective at avoiding wave reflections at the boundaries, they can be computationally more demanding than less used hybrid ABCs. We show here that a proposed hybrid ABC formulation, with nested Higdon's boundary conditions, is the most cost-effective method among the methods considered here, for being as effective as or more effective than PML and other schemes but also for being computationally more efficient.
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Xu, Run-Wen, i Li-Xin Guo. "Application of Hybrid Finite Element-Boundary Integral Algorithm for Solving Electromagnetic Scattering from Multiple Objects over Rough Sea Surface". International Journal of Antennas and Propagation 2014 (2014): 1–10. http://dx.doi.org/10.1155/2014/301934.
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A hybrid algorithm of the finite element method (FEM) is presented to solve two-dimensional (2D) scattering from multiple dielectric objects above the rough sea surface. Compared with traditional FEM based on approximate absorbing boundaries, FEM based on the boundary integral method (BIM) can reduce the calculational region and solution time of the scattering problem. In the hybrid method, the whole computational region is divided into the sea surface and multiple isolate interior regions for the dielectric objects. FEM is only used to simulate the scattering from multiple interior regions enclosing the objects, whereas the large sea is considered exactly by BIM. The coupled interaction among the isolate interior regions and the sea can be taken into account by BIM. The hybrid technique presented here is efficient and versatile for addressing scattering from multiple arbitrary targets above rough sea surfaces. Scattering properties of multiple dielectric objects above the sea surface under different conditions are discussed in detail.
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Acanfora, Valerio, Ferdinando Baldieri, Antonio Garofano, Francesco Fittipaldi i Aniello Riccio. "On the Crashworthiness Behaviour of Innovative Sandwich Shock Absorbers". Polymers 14, nr 19 (4.10.2022): 4163. http://dx.doi.org/10.3390/polym14194163.
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Increasing the impact resistance properties of any transport vehicle is a real engineering challenge. This challenge is addressed in this paper by proposing a high-performing structural solution. Hence, the performance, in terms of improvement of the energy absorbing characteristics and the reduction of the peak accelerations, of highly efficient shock absorbers integrated in key locations of a minibus chassis have been assessed by means of numerical crash simulations. The high efficiency of the proposed damping system has been achieved by improving the current design and manufacturing process of the state-of-the-art shock absorbers. Indeed, the proposed passive safety system is composed of additive manufactured, hybrid polymer/composite (Polypropylene/Composite Fibres Reinforced Polymers—PP/CFRP) shock absorbers. The resulting hybrid component combines the high stiffness-to-mass and strength-to-mass ratios characteristic of the composites with the capability of the PP to dissipate energy by plastic deformation. Moreover, thanks to the Additive Manufacturing (AM) technique, low-mass and low-volume highly-efficient shock-absorbing sandwich structures can be designed and manufactured. The use of high-efficiency additively manufactured sandwich shock absorbers has been demonstrated as an effective way to improve the passive safety of passengers, achieving a reduction in the peak of the reaction force and energy absorbed in the safety cage of the chassis’ structure, respectively, up to up to 30 kN and 25%.
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Sakthivel, Santhanam, Selvaraj Senthil Kumar, Eshetu Solomon, Gedamnesh Getahun, Yohaness Admassu, Meseret Bogale, Mekdes Gedilu, Alemu Aduna i Fasika Abedom. "Sound absorbing and insulating properties of natural fiber hybrid composites using sugarcane bagasse and bamboo charcoal". Journal of Engineered Fibers and Fabrics 16 (styczeń 2021): 155892502110448. http://dx.doi.org/10.1177/15589250211044818.
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This research paper reports a study on thermal and sound insulation samples developed from sugarcane bagasse and bamboo charcoal for automotive industry applications. The sugarcane bagasse and bamboo charcoal fiber is a potential source of raw material that can be considered for thermal and sound insulation applications. Natural fibers are commonly used in diverse applications and one of the most important applications is sound absorption. Natural fiber hybrid composite currently is in greater demand in industries because of their advantages such as low cost, biodegradability, acceptable physical properties, and so on. Eco-friendly sound-absorbing composite materials have been developed using bamboo charcoal and sugarcane bagasse fibers. From these fibers five types of natural fiber green composite were developed using the compression bonding technique. The natural composite noise control performance contributes to its wider adoption as sound absorbers. The sound absorption coefficient was measured according to ASTM E 1050 by the Impedance tube method. The physical properties of natural fiber composites such as thickness, density, porosity, air permeability, and thermal conductivity were analyzed for all samples in accordance with ASTM Standard. The result exposed that natural fiber green composite were absorbing the sound resistance of more than 70% and the natural fibers composites provide the best acoustic absorption properties, these composite materials have adequate moisture resistance at high humidity conditions without affecting the insulation and acoustic properties.
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Cho, Youn Ho, Joseph L. Rose i He Geon Kwun. "SH Guided Wave Scattering in a Structure with Thickness Variation". Key Engineering Materials 321-323 (październik 2006): 792–94. http://dx.doi.org/10.4028/www.scientific.net/kem.321-323.792.
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Presented in this paper is a numerical approach to extract useful features of SH guided wave scattering in a Plate-like structure with thickness variation. The problem statement is chosen to establish a physically based guideline for mode selection and data analyses in power industry application. The hybrid BEM technique with absorbing boundaries on the structure cross-sections is proposed to calculate reflection and transmission from thickness variation. Sample numerical data is presented as a function of incident mode, frequency and defect geometry. Mode optimization is proposed to enhance penetration power and quantify geometry change based on various interesting features including reverberation pattern of scattering fields.
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Guentri, Hocine, Abdeldjalil Dahbi, Tayeb Allaoui, Salim Aoulmit i Ahmed Bouraiou. "Development of a Control Strategy for the Hybrid Energy Storage Systems in Standalone Microgrid". International journal of electrical and computer engineering systems 14, nr 5 (5.06.2023): 575–84. http://dx.doi.org/10.32985/ijeces.14.5.9.
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The intermediate energy storage system is very necessary for the standalone multi-source renewable energy system to increase stability, reliability of supply, and power quality. Among the most practical energy storage solutions is combining supercapacitors and chemical batteries. However, the major problem in this kind of application is the design of the power management, as well as the control scheme of hybrid energy storage systems. The focal purpose of this paper is to develop a novel approach to control DC bus voltage based on the reference power's frequency decomposition. This paper uses a storage system combined of batteries and supercapacitors. These later are integrated in the multi-source renewable energy system to supply an AC load. This technique uses the low-pass filters' properties to control the DC bus voltage by balancing the generated green power and the fluctuating load. The hybrid storage system regulates power fluctuations by absorbing surplus power and providing required power. The results show good performances of the proposed control scheme, such as low battery current charge/discharge rates, lower current stress level on batteries, voltage control improvements, which lead to increase the battery life.
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Elson, Daniel S., Rui Li, Christopher Dunsby, Robert Eckersley i Meng-Xing Tang. "Ultrasound-mediated optical tomography: a review of current methods". Interface Focus 1, nr 4 (2.06.2011): 632–48. http://dx.doi.org/10.1098/rsfs.2011.0021.
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Ultrasound-mediated optical tomography (UOT) is a hybrid technique that is able to combine the high penetration depth and high spatial resolution of ultrasound imaging to overcome the limits imposed by optical scattering for deep tissue optical sensing and imaging. It has been proposed as a method to detect blood concentrations, oxygenation and metabolism at depth in tissue for the detection of vascularized tumours or the presence of absorbing or scattering contrast agents. In this paper, the basic principles of the method are outlined and methods for simulating the UOT signal are described. The main detection methods are then summarized with a discussion of the advantages and disadvantages of each. The recent focus on increasing the weak UOT signal through the use of the acoustic radiation force is explained, together with a summary of our results showing sensitivity to the mechanical shear stiffness and optical absorption properties of tissue-mimicking phantoms.
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Lin, Chuangxin, Vadim Monteiller, Kai Wang, Tianshi Liu, Ping Tong i Qinya Liu. "High-frequency seismic wave modelling of the deep Earth based on hybrid methods and spectral-element simulations: a conceptual study". Geophysical Journal International 219, nr 3 (12.09.2019): 1948–69. http://dx.doi.org/10.1093/gji/ggz413.
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SUMMARY Over the past few decades, seismic studies have revealed complex structural anomalies in the Earth’s deep interior at various scales, such as large low-shear-velocity provinces (LLSVPs) and ultra-low velocity zones (ULVZs) in the lowermost mantle, and small-scale scatterers in the mid-mantle. These structures which are critical for better understanding of the geodynamics and evolution of the deep Earth, need to be further resolved by high-resolution imaging techniques. The spectral-element method (SEM) can be used to accurately simulate seismic wave propagation in heterogeneous Earth models, and its application in full-waveform inversion (FWI) provides a promising high-resolution and high-fidelity imaging technique. But it can be computationally prohibitive when used to model small scale structures in the deep Earth based upon high-frequency seismic waves. The heavy computational cost can be circumvented by using hybrid methods, which restrict the main computation by SEM solver to only a small target region (e.g. above the CMB) encompassing possible 2-D/3-D anomalies, and apply efficient analytical or numerical methods to calculate the wavefield for 1-D background models. These forward modelling tools based on hybrid methods can be then used in the so-called ‘box tomography’ approach to resolve fine-structures in the deep Earth. In this study, we outline the theory of a hybrid method used to model small scale structures in the deep Earth and present its implementation based on SEM solvers in a three-step workflow. First, the wavefield generated by the source is computed for the 1-D background model with traction and velocity saved for the virtual boundary of the target region, which are then used as boundary inputs to simulate the wavefield in the target region based on absorbing boundary condition in SEM. In the final step, the total wavefield at receivers is reconstructed based upon the total wavefield on the virtual boundary computed in the previous step. As a proof-of-concept study, we demonstrate the workflow of the hybrid method based on a 2-D SEM solver. Examples of the hybrid method applied to a coupled fluid–solid model show that our workflow can accurately recover the scattered waves back to the surface. Furthermore, we benchmark the hybrid method on a realistic heterogeneous Earth model built from AK135-F and show how teleseismic scattered waves can be used to model deep Earth structures. By documenting the theory and SEM implementation of the hybrid method, our study lays the foundation for future two-way coupling of 3-D SEM solver with other efficient analytic or numerical 1-D solvers.
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Taleb, Maamar, Mohamed Amine Fnaiech i Khaled Zehar. "An Enhanced Hybrid Grid Connected Photovoltaic System Using Voltage Oriented Controller and Class D Chopper". Renewable Energy and Power Quality Journal 21, nr 1 (lipiec 2023): 69–75. http://dx.doi.org/10.24084/repqj21.225.
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The performance of a shunt interconnection made from a PV system, a three phase grid voltage supply, and a DC shunt motor (DC load) is investigated The PV system participates with maximum powers to the overall interconnection active power flow. It uses a class D chopper circuitry controlled properly by a typical maximum power point tracker (MPPT) controller. The grid has the role of supplying active power in case of any power deficiency needed by the DC motor load. Similarly, it has also the role of absorbing active power in case of any additional power generated by the PV system and not needed by the DC load. This is done by using an AC/DC power electronic converter. The AC/DC power electronic converter operates either under rectifier or inverter modes. The AC/DC power electronic converter is also operated under the next two conditions: 1-the reactive power expected at the grid voltage bus should be nearly null, 2-harmonics currents often encountered in the grid line currents waveforms should be tolerable. The two latter conditions are fulfilled by using the principle of voltage oriented control (VOC) technique. The performance of the investigated interconnection is simulated in Matlab/Simulink platform. Quite satisfactory results are obtained. The satisfaction about the obtained simulation results persists on being able to integrate easily the PV system with the AC grid while extracting maximum power from the PVG and having a unity power factor at the AC grid bus and less encountered harmonics in the ac line currents.
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Moreno Candel, Francisco, Fátima Felisa Acosta Hernández, Itahisa Pérez-Conesa i José Antonio Aguilar Galea. "Procesado térmico de moldes confeccionados con revestimiento de joyería mediante microondas por calentamiento híbrido". Bellas Artes. Revista de Artes plásticas, Estética, Diseño e Imagen, nr 15 (2021): 89–107. http://dx.doi.org/10.25145/j.bbaa.2021.15.04.
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This research aims to contribute to the understanding and control of the processing of materials involved in artistic casting by microwaves, in order to facilitate this type of energy sources in the thermal processes of dewaxing. Specifically, the behavior of small samples made with commercial refractory coatings on simple wax models was studied. An adaptation and compatibilization of the conventional technique of fused jewelry was designed to validate an integral treatment with this energy alternative. On the one hand, a suitable time/power curve was designed for the initial dewaxing and drying of these pastes, taking into account the dielectric properties of the water present in their confection. On the other hand, a feasible procedure was studied for the development of their burning, through the use of hybrid heating using silicon carbide (SiC-β) as a susceptor. In order to apply a step temperature, a double muffle combining transparent and absorbing materials with the capacity to reach 750°C with MW power of 700w was fabricated. The results obtained intensified the interest in studying a thermal processing for the dewaxing and firing of refractory linings with larger models and more complex shapes oriented to jewelry and small format sculpture.
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A. Badr, Mohammed, Ahmed M. Atallah i Mona A. Bayoumi. "Performance Analysis of SMES Integrated with Offshore Wind Farms to Power Systems through MT-HVDC". Indonesian Journal of Electrical Engineering and Computer Science 4, nr 1 (4.11.2016): 1. http://dx.doi.org/10.11591/ijeecs.v4.i1.pp1-9.
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<p>With the increase in the development of offshore wind farm (OWF) around the world, this paper describes OWF consisting of permanent magnet synchronous generator (PMSG) wind turbines connected to Active network (AC grid) and Passive network (loads) through Multi Terminal High voltage direct current(MT-HVDC) transmission system. This paper discusses the effect of using a Superconducting Magnetic Energy Storage (SMES) unit in a hybrid power system that contains OWF. In this paper, we have aggregated 300 wind turbines of 1.5 MW PMSG using an aggregation technique (multi full aggregated model using equivalent wind speed (MFAM_EWS)). Furthermore, we have used a detector to detect any tripping of any wind turbine and substitute the shortage of power due to this loss of wind turbines immediately through SMES. The Active network in this paper should have a minimum of 150 MW power to be supplied by controlling the SMES unit (absorbing or providing power according to the system requirement). Simulation has been carried out by MATLAB/Simulink program to test the effectiveness of the SMES unit during tripping some of the wind turbines, fluctuation in wind speeds, load change and voltage dips. </p>
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Chankaya, Mukul, Ikhlaq Hussain, Aijaz Ahmad, Hasmat Malik i Majed A. Alotaibi. "Stability Analysis of Chaotic Grey-Wolf Optimized Grid-Tied PV-Hybrid Storage System during Dynamic Conditions". Electronics 11, nr 4 (13.02.2022): 567. http://dx.doi.org/10.3390/electronics11040567.
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This paper presents the stability improvement of the three-phase four-wire (3P-4W) grid-tied PV-hybrid energy storage system (HESS) using chaotic grew wolf optimization (CGWO) for DC bus voltage (Vdc) and AC bus voltage (Vpcc) control. The CGWO tuned fractional order proportional–integral (FOPI) controllers reduce the Vdc and Vpcc variations during diverse, dynamic conditions, i.e., sudden irradiation variations, deep voltage sag/swell, etc. The DC bus is responsible for the current injection/extraction control, maximum PV power extraction, bi-directional power flow, dc second-harmonics component elimination, and active power balance. At the point of common coupling (PCC), the AC bus is accountable for bi-directional power flow and active and reactive power control. The two-level voltage source converter (VSC) is controlled by a novel variable step-size incremental least mean square (VSS-ILMS) in zero voltage regulation (ZVR) mode. Due to its varying step size, VSC control is less prone to noise signals offers better stability, improved convergence rate, dc offset rejection, and tracking speed during dynamics, i.e., large oscillations. A battery and ultracapacitor are coupled to the DC link by buck-boost converters in the HESS. To regulate power transit between the DC bus and the grid, the HESS current control technique is designed to shift frequently from charging to discharging stage and vice versa. The novelty of the PV-HESS system lies in CGWO tuned VSS-ILMS control of VSC, which effectively and efficiently filter out the active fundamental constituents of load current and eliminate dc offset from VSC output. The HESS control maintains the DC bus voltage profile by absorbing and delivering energy (during dynamic conditions) rather than curtailing it. The presented system is simulated in a MATLAB/SIMULINK environment. The simulation results in graphical and numerical forms verify the stable and satisfactory operation of the proposed system as per IEEE519 standard.
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Zare, Mehdi, i Sadegh Sadeghi. "Development of hybrid method for coupled conduction-radiation heat transfer in two-dimensional irregular enclosure considering thermo-radiative effects and varying thermal conductivity". International Journal of Numerical Methods for Heat & Fluid Flow 30, nr 4 (19.04.2019): 1815–37. http://dx.doi.org/10.1108/hff-11-2018-0667.
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Purpose This study aims to perform a comprehensive investigation to model the thermal characteristics of a coupled conduction-radiation heat transfer in a two-dimensional irregular enclosure including a triangular-shaped heat source. Design/methodology/approach For this purpose, a promising hybrid technique based on the concepts of blocked-off method, FVM and DOM is developed. The enclosure consists of several horizontal, vertical and oblique walls, and thermal conductivity within the enclosure varies directly with temperature and indirectly with position. To simplify the complex geometry, a promising mathematical model is introduced using blocked-off method. Emitting, absorbing and non-isotropic scattering gray are assumed as the main radiative characteristics of the steady medium. Findings DOM and FVM are, respectively, applied for solving radiative transfer equation (RTE) and the energy equation, which includes conduction, radiation and heat source terms. The temperature and heat flux distributions are calculated inside the enclosure. For validation, results are compared with previous data reported in the literature under the same conditions. Results and comparisons show that this approach is highly efficient and reliable for complex geometries with coupled conduction-radiation heat transfer. Finally, the effects of thermo-radiative parameters including surface emissivity, extinction coefficient, scattering albedo, asymmetry factor and conduction-radiation parameter on temperature and heat flux distributions are studied. Originality/value In this paper, a hybrid numerical method is used to analyze coupled conduction-radiation heat transfer in an irregular geometry. Varying thermal conductivity is included in this analysis. By applying the method, results obtained for temperature and heat flux distributions are presented and also validated by the data provided by several previous papers.
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Zhong, Chaowen, Ke Yan, Yuting Dai, Ning Jin i Bing Lou. "Energy Efficiency Solutions for Buildings: Automated Fault Diagnosis of Air Handling Units Using Generative Adversarial Networks". Energies 12, nr 3 (7.02.2019): 527. http://dx.doi.org/10.3390/en12030527.
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Automated fault diagnosis (AFD) for various energy consumption components is one of the main topics for energy efficiency solutions. However, the lack of faulty samples in the training process remains as a difficulty for data-driven AFD of heating, ventilation and air conditioning (HVAC) subsystems, such as air handling units (AHU). Existing works show that semi-supervised learning theories can effectively alleviate the issue by iteratively inserting newly tested faulty data samples into the training pool when the same fault happens again. However, a research gap exists between theoretical AFD algorithms and real-world applications. First, for real-world AFD applications, it is hard to predict the time when the same fault happens again. Second, the training set is required to be pre-defined and fixed before being packed into the building management system (BMS) for automatic HVAC fault diagnosis. The semi-supervised learning process of iteratively absorbing testing data into the training pool can be irrelevant for industrial usage of the AFD methods. Generative adversarial network (GAN) is well-known as an unsupervised learning technique to enrich the training pool with fake samples that are close to real faulty samples. In this study, a hybrid generative adversarial network (GAN) is proposed combining Wasserstein GAN with traditional classifiers to perform fault diagnosis mimicking the real-world scenarios with limited faulty training samples in the training process. Experimental results on real-world datasets demonstrate the effectiveness of the proposed approach for fault diagnosis problems of AHU subsystem.
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Beard, Paul. "Biomedical photoacoustic imaging". Interface Focus 1, nr 4 (22.06.2011): 602–31. http://dx.doi.org/10.1098/rsfs.2011.0028.
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Photoacoustic (PA) imaging, also called optoacoustic imaging, is a new biomedical imaging modality based on the use of laser-generated ultrasound that has emerged over the last decade. It is a hybrid modality, combining the high-contrast and spectroscopic-based specificity of optical imaging with the high spatial resolution of ultrasound imaging. In essence, a PA image can be regarded as an ultrasound image in which the contrast depends not on the mechanical and elastic properties of the tissue, but its optical properties, specifically optical absorption. As a consequence, it offers greater specificity than conventional ultrasound imaging with the ability to detect haemoglobin, lipids, water and other light-absorbing chomophores, but with greater penetration depth than purely optical imaging modalities that rely on ballistic photons. As well as visualizing anatomical structures such as the microvasculature, it can also provide functional information in the form of blood oxygenation, blood flow and temperature. All of this can be achieved over a wide range of length scales from micrometres to centimetres with scalable spatial resolution. These attributes lend PA imaging to a wide variety of applications in clinical medicine, preclinical research and basic biology for studying cancer, cardiovascular disease, abnormalities of the microcirculation and other conditions. With the emergence of a variety of truly compelling in vivo images obtained by a number of groups around the world in the last 2–3 years, the technique has come of age and the promise of PA imaging is now beginning to be realized. Recent highlights include the demonstration of whole-body small-animal imaging, the first demonstrations of molecular imaging, the introduction of new microscopy modes and the first steps towards clinical breast imaging being taken as well as a myriad of in vivo preclinical imaging studies. In this article, the underlying physical principles of the technique, its practical implementation, and a range of clinical and preclinical applications are reviewed.
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Yu, L., S. Ahmad, Sivanesan Appadu, I. Kong, Mou'ad Tarawneh i Moayad Flaifel. "Comparison of magnetic and microwave absorbing properties between multiwalled carbon nanotubes nanocomposite, nickel zinc ferrite nanocomposite and hybrid nanocomposite". World Journal of Engineering 11, nr 4 (1.08.2014): 317–22. http://dx.doi.org/10.1260/1708-5284.11.4.317.
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Three types of fillers were incorporated in the thermoplastic natural rubber by melt blending process. They are NiZn ferrite, multiwalled carbon nanotubes, and hybrid NiZn ferrite/multiwalled carbon nanotubes followed by weight ratio of 1:1. Their magnetic properties and microwave absorbing properties were investigated. The ball-milled techniques, resulted good filler dispersion in hybrid nanocomposite, proven by the matching saturation magnetization experimental values with the theory calculation. It was found that the magnetic property strongly depends on the amount of magnetic particles in the nanocomposites. The mixing of two different types of filler (multiwalled carbon nanotubes and NiZn ferrite) showed an enhancement of the microwave properties at lower filler loading.
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Lee, Wonho, Jinhoon Kim i Changbae Park. "Topology Optimization for Polymeric Foam Shock-Absorbing Structure Using Hybrid Cellular Automata". International Journal of Automation Technology 8, nr 3 (5.05.2014): 365–75. http://dx.doi.org/10.20965/ijat.2014.p0365.
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Foam shock-absorbing structures such as cushioned packages are often utilized to protect various products from mechanical shock and vibration during transportation. The goal of packaging design engineers is to design a cushioned package structure that improves the shock-absorbing performance and minimizes the volume of the package. Some optimization techniques, combined with computational simulation, provide engineers with a way to design an optimal structure. In this paper, we propose a modified topology optimization method suitable for a polymeric foam shock-absorbing structure under dynamic drop loads in multiple directions. Our approach uses a heuristic topology optimization method, known as the Hybrid Cellular Automata (HCA). The HCA algorithm uniformly distributes internal energy density and controls the relative density of Cellular Automata (CAs) making up the design space. This allows the algorithm to maintain or increase the performance of shock absorption and to decrease the amount of material. In particular, this paper presents a modified Solid IsotropicMaterial with Penalization (SIMP) model for foam materials, which parameterizes the design region and interpolates the material properties. We attempt to optimize a simple bottom-cushioned package for a refrigerator by using the proposed foam SIMP model with commercial software: LS-DYNA for drop dynamic simulation and LS-OPT/Topology for the HCA algorithm. Drop simulation and topology optimization are performed considering multiple drop-directions. As a result, our method removes elements that are not related to the shock-absorption performance and provide an optimal cushioning structure using foam material.
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Paul Anule, Asoshi, Moshood Abiola Hambali i Chukwudi Jennifer Ifeoma. "Review of Sentiment Analysis: An Hybrid Approach". Middle East Journal of Applied Science & Technology 05, nr 04 (2022): 24–54. http://dx.doi.org/10.46431/mejast.2022.5405.
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Sentiment analysis is acknowledged as detecting thoughts used from field content features additionally it's recognized while one linked to the main parts of standpoint extraction. Through this type of process, we will be able to discover if a movie script is positive, negative, or natural. Using this research, a feeling examination is executed along with calvados data. The text message sensation analyzer combines organic and natural language processing (NLP) and even machine studying techniques to provide measured assessment rankings to be able to entities, subjects, themes, and groups in a term or key phrase. Inside expressing feelings, the particular polarity of calvados written content reviews can always be graded for the damaging to good range utilizing the education algorithm. The certain current decade presents seen substantial improvements in artificial brains; along with the device mastering revolution offers converted the complete AI sector. In the end, unit learning techniques include grown to always be an important aspect of any design and style in today's absorbing world. However, this ensemble of researching techniques promises for anyone who is part of motorization using the removal of common regulations for textual written content message and sentiment category activities. This kind of particular thesis has to style and carry out a good superior functionality matrix employing ensemble studying intended for sentiment category while well as software. With this paper, we possess analyzed the well-known techniques adopted within the classical Emotion Analysis problem associated with analyzing Elections evaluations like; Support Vector Machine (SVM) and Linear Regression (LR) for the effective detection of sentiments from the dataset obtained from the Kaggle machine learning repository.
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Yan, Hong Yuan, Zhao Li, Tian Hui Hu i Ye Hong Han. "Preparation and Characteristic of the New Magnetic Organic–Inorganic Hybrid Molecularly Imprinted Microsphere Materials". Applied Mechanics and Materials 184-185 (czerwiec 2012): 1106–9. http://dx.doi.org/10.4028/www.scientific.net/amm.184-185.1106.
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The new magnetic organic–inorganic hybrid composite imprinted microspheres (MHCIM) based on Fe3O4 nanospheres as core structure and imprinted materials as shell structure have been synthesized by surface molecularly imprinted technique using dummy template strategy. Scanning electron microscopy images showed that the MHCIM were with a diameter distribution (10-120 µm) and cross-linking, spherical shape, and porous morphologies. The resultant MHCIM incorporating molecular recognition and magnetic separation properties can provide a highly selective absorbent materials for trace extraction and isolation target molecules from complicated biological matrix.
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Bresolin, Bianca-Maria, Samia Ben Hammouda i Mika Sillanpää. "An Emerging Visible-Light Organic–Inorganic Hybrid Perovskite for Photocatalytic Applications". Nanomaterials 10, nr 1 (7.01.2020): 115. http://dx.doi.org/10.3390/nano10010115.
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The development of visible-light active photocatalysts is a current challenge especially energy and environmental-related fields. Herein, methylammonium lead iodide perovskite (MAIPb) was chosen as the novel semiconductor material for its ability of absorbing visible-light. An easily reproducible and efficient method was employed to synthesize the as-mentioned material. The sample was characterized by various techniques and has been used as visible-light photocatalyst for degradation of two model pollutants: rhodamine B (RhB) and methylene-blue (MB). The photo-degradation of RhB was found to achieve about 65% after 180 min of treatment. Moreover, the efficiency was enhanced to 100% by assisting the process with a small amount of H2O2. The visible-light activity of the photocatalyst was attributed to its ability to absorb light as well as to enhance separation of photogenerated carriers. The main outcome of the present work is the investigation of a hybrid perovskite as photocatalyst for wastewater treatment.
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Olubamiji, Adeola D., Zohreh Izadifar, Ning Zhu, Tuanjie Chang, Xiongbiao Chen i B. Frank Eames. "Using synchrotron radiation inline phase-contrast imaging computed tomography to visualize three-dimensional printed hybrid constructs for cartilage tissue engineering". Journal of Synchrotron Radiation 23, nr 3 (14.04.2016): 802–12. http://dx.doi.org/10.1107/s1600577516002344.
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Synchrotron radiation inline phase-contrast imaging combined with computed tomography (SR-inline-PCI-CT) offers great potential for non-invasive characterization and three-dimensional visualization of fine features in weakly absorbing materials and tissues. For cartilage tissue engineering, the biomaterials and any associated cartilage extracellular matrix (ECM) that is secreted over time are difficult to image using conventional absorption-based imaging techniques. For example, three-dimensional printed polycaprolactone (PCL)/alginate/cell hybrid constructs have low, but different, refractive indices and thicknesses. This paper presents a study on the optimization and utilization of inline-PCI-CT for visualizing the components of three-dimensional printed PCL/alginate/cell hybrid constructs for cartilage tissue engineering. First, histological analysis using Alcian blue staining and immunofluorescent staining assessed the secretion of sulfated glycosaminoglycan (GAGs) and collagen type II (Col2) in the cell-laden hybrid constructs over time. Second, optimization of inline PCI-CT was performed by investigating three sample-to-detector distances (SDD): 0.25, 1 and 3 m. Then, the optimal SDD was utilized to visualize structural changes in the constructs over a 42-day culture period. The results showed that there was progressive secretion of cartilage-specific ECM by ATDC5 cells in the hybrid constructs over time. An SDD of 3 m provided edge-enhancement fringes that enabled simultaneous visualization of all components of hybrid constructs in aqueous solution. Structural changes that might reflect formation of ECM also were evident in SR-inline-PCI-CT images. Summarily, SR-inline-PCI-CT images captured at the optimized SDD enables visualization of the different components in hybrid cartilage constructs over a 42-day culture period.
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Chen, Juan, i Chunhui Mou. "The HIE-FDTD Method for Simulating Dispersion Media Represented by Drude, Debye, and Lorentz Models". Nanomaterials 13, nr 7 (26.03.2023): 1180. http://dx.doi.org/10.3390/nano13071180.
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The hybrid implicit–explicit finite-difference time-domain (HIE-FDTD) method is a weakly conditionally stable finite-difference time-domain (FDTD) method that has attracted much attention in recent years. However due to the dispersion media such as water, soil, plasma, biological tissue, optical materials, etc., the application of the HIE-FDTD method is still relatively limited. Therefore, in this paper, the HIE-FDTD method was extended to solve typical dispersion media by combining the Drude, Debye, and Lorentz models with hybrid implicit–explicit difference techniques. The advantage of the presented method is that it only needs to solve a set of equations, and then different dispersion media including water, soil, plasma, biological tissue, and optical materials can be analyzed. The convolutional perfectly matched layer (CPML) boundary condition was introduced to truncate the computational domain. Numerical examples were used to validate the absorbing performance of the CPML boundary and prove the accuracy and computational efficiency of the dispersion HIE-FDTD method proposed in this paper. The simulated results showed that the dispersion HIE-FDTD method could not only obtain accurate calculation results, but also had a much higher computational efficiency than the finite-difference time-domain (FDTD) method.
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Chaabane, Raoudha, Faouzi Askri i Ben Nasrallah. "A new hybrid algorithm for solving transient combined conduction radiation heat transfer problems". Thermal Science 15, nr 3 (2011): 649–62. http://dx.doi.org/10.2298/tsci100722015c.
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A new algorithm based on the lattice Boltzmann method (LBM) and the Control Volume Finite Element Method (CVFEM) is proposed as an hybrid solver for two dimensional transient conduction and radiation heat transfer problems in an optically emitting, absorbing and scattering medium. The LBM was used to solve the energy equation and the CVFEM was used to compute the radiative information. The advantages of the proposed methodology is to avoid problems that confronted when previous techniques are used to predict radiative heat transfer, essentially, in complex geometries and when there is scattering and/or non-black boundaries surfaces. This method combination, which is applied for the first time to solve this unsteady combined mode of heat transfer, has been found to accurately predict the effects of various thermo-physical parameters such as the scattering albedo, the conduction-radiation parameter and the extinction coefficient on temperature distribution. The results of the LBM-CVFEM combination were found to be in excellent agreement with the LBM-CDM (Collapsed Dimension Method)this proposed numerical approach include, among others, simple implementation on a computer, accurate CPU time, and capability of stable simulation.
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Petukhov, Anton N., Artem A. Atlaskin, Kirill A. Smorodin, Sergey S. Kryuchkov, Dmitriy M. Zarubin, Maria E. Atlaskina, Anastasia N. Petukhova i in. "An Efficient Technique for Ammonia Capture in the Haber–Bosch Process Loop—Membrane-Assisted Gas Absorption". Polymers 14, nr 11 (30.05.2022): 2214. http://dx.doi.org/10.3390/polym14112214.
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The present study continues the development and enhancement of a highly efficient unique hybrid technique—membrane-assisted gas absorption in designing the separation unit, which provides the improvement in mass-transfer of a target component during the ammonia capture process from a process loop of the Haber–Bosch technological route. In order to minimize the absorbent volume to membrane area ratio, the special separation cell was designed based on a combination of two types of hollow fiber membranes, dense gas separation membrane and porous pervaporation membrane. The separation performance tests were implemented under two sets of conditions, sweeping the bore (permeate) side of a cell with helium and hydrogen-nitrogen mix. For both cases, the membrane-assisted gas absorption cell demonstrated high separation efficiency, and the ammonia concentration in the permeate was never lower than 81 mol%; meanwhile, under the hydrogen-nitrogen bore sweep conditions, the ammonia concentration in the permeate reached 97.5 mol% in a single-step process. Nevertheless, there is a product purity–recovery rate trade-off, which is a typical issue for separation processes.
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Safarishaal, Masoud, i Mohammad Sarvi. "New hybrid maximum power point tracking methods for fuel cell using artificial intelligent". AIP Advances 13, nr 4 (1.04.2023): 045207. http://dx.doi.org/10.1063/5.0144806.
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An efficient way to raise the proton exchange membrane fuel cell’s (PEMFC’s) power generation efficiency and power supply quality is to use maximum power point tracking (MPPT). Conventional MPPT approaches often have difficulty producing an effective control effect due to the PEMFC’s inherent nonlinear characteristics. Another challenge for systems that track maximum power points is dealing with fast changes in operational conditions that affect FC’s maximum power point (MPP). The main contribution of this study is the introduction of two artificial intelligence-based MPP control approaches for fuel cells operating under rapidly changing operating conditions. These methods are based on imperialist competitive algorithm-trained neural networks and adaptive neuro-fuzzy inference systems (ANFIS) (ICA NN). The proposed approaches determine the fuel cell voltage that corresponds to the maximum power point. Following that, a fuzzy logic controller is used to modify the duty cycle of a DC/DC boost converter for FC MPP tracking. The MATLAB environment is used to run simulations. The results of the proposed method are compared with those of the conventional fuzzy method. The results demonstrate that the suggested solutions function excellently in both normal operating conditions and quickly varying operating conditions. On the other hand, the suggested approaches can quickly locate and monitor the MPP of FC. Additionally, the suggested techniques increase the FC system’s efficiency by absorbing more power.
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Vanpeene, Victor, Jakub Drnec, Tobias Schulli, Ennio Capria i Julie Villanova. "Teesmat an Open Innovation Test Bed for Electrochemical Devices: Example of X-Ray Nano-Tomography As Characterization Tool for Battery Analysis". ECS Meeting Abstracts MA2022-01, nr 1 (7.07.2022): 54. http://dx.doi.org/10.1149/ma2022-01154mtgabs.
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The recent rapid increase of the demand of higher energy density along with higher power density lithium-ion batteries (LiBs) requires the development of advanced cathode/anode materials with higher capacity. These challenges can be addressed providing that powerful characterization tools are able to probe the degradation phenomena occurring at multiple scale. In this context, the TEESMAT platform aims to widen the access to a large panel of characterization techniques among different partners across Europe for solving industrial problematics in energy related field. Among these, X-ray tomography has been used as non-invasive 3D investigation tool that spread along a wide range of applications in order to probe at different length scale their microstructure. Moreover, phase contrast imaging has brought to light a practical way to enhance visibility between weak absorbing materials and/or small details of differing refractive index within structure, and thus accessing a sharpen overview of the 3D morphology of complex material, which is of particular interest in the frame of energy-related materials. This presentation will focus on various industrial case studies such as NMC-based and LFP-based all solid-state batteries, hybrid Li-ion supercapacitor and current collector manufacturing. The results presented are part of the TEESMAT project, which received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 814106.
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Kaydashev, Vladimir, Boris Khlebtsov, Maxim Kutepov, Anatoliy Nikolskiy, Alexey Kozakov, Alexey Konstantinov, Alexey Mikheykin, Gevork Karapetyan i Evgeni Kaidashev. "Photothermal Effect and Phase Transition in VO2 Enhanced by Plasmonic Particles". Materials 16, nr 7 (24.03.2023): 2579. http://dx.doi.org/10.3390/ma16072579.
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Phase change metasurfaces based on VO2, which are pre-heated with electric current and optically addressed by projected structured light hologram, are considered to become a new paradigm in programmed THz/middle IR flat optics. Macroscopic quasi-homogeneous arrays of Au nanoparticles show large near IR absorption and a significant photothermal effect capable of boosting a light-triggered switching of VO2 and are to be carefully examined. We propose a new approach to simultaneously probe the altered temperature and electric conductivity of a hybrid Au particle-VO2 film composite by monitoring a phase shift and attenuating a surface acoustic wave in a YX128° cut LiNbO3 substrate. The method shows a temperature resolution of 0.1 °C comparable with the best existing techniques for studying nanoobjects and surfaces. The laser-induced photothermal effects were characterized in a macroscopic array of Au nanostars (AuNSts) with different surface coverage. In a monolayer of 10 nm Au, coupled plasmonic nanoparticles were deposited on the LiNbO3 substrate. An optically triggered insulator-metal transition assisted by photothermal effect in AuNSts/VO2/TiO2/LiNbO3 composites was studied at varied light power. We believe that the proposed SAW-based method is of significant importance for the characterization and optimization of radiation absorbing or/and electrically heated elements of metasurfaces and other devices for lab-on-chip and optical communication/processor technology.
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Arshad, Sazmal Effendi, Zarina Amin, Perng Yang Puah, Mohd Sani Sarjadi, Baba Musta i Md Lutfor Rahman. "Synthesis of Silica Gel Supported Amidoxime Ligand for Adsorption of Copper and Iron from Aqueous Media". Asian Journal of Chemistry 31, nr 12 (16.11.2019): 3035–40. http://dx.doi.org/10.14233/ajchem.2019.22333.
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Organic-inorganic hybrid polymers have been demonstrated to be an efficient technique for the adsorption of pollutants present in water. Silica gel adsorbent has been applied in this field due to promising characters, such as thermally stable, reusability and high metal ion adsorption capacities. Here, silica gel supported acrylonitrile functional group (silica-APTS-DPN) was reacted with hydroxylamine to yield silica gel supported amidoxime ligand (SBA). All the functionalized silica gel adsorbents were characterized by FTIR. In terms of metal ions adsorption, SBA revealed good absorption capacities towards both copper (Cu2+) (172 mg g-1) and iron (Fe3+) (168 mg g-1) ions at pH 6 and followed the order of Cu2+ > Fe3+. Increased pH condition was beneficial for both metal ions adsorption. The adsorption kinetics of both ions followed the pseudo-first-order model within 0-60 min of adsorption time. Langmuir and Freundlich isotherm models were both applied to study the adsorption behaviour, Freundlich isotherm model (R2 > 0.99) proved to be a better fit, which propose that multilayer adsorption occurred on the silica gel grafted with amidoxime ligand. Finally, this study proved that the silica gel supported amidoxime ligand was successfully applied as an absorbent for the removal of both copper and iron from aqueous media.
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Rius-Ayra, Oriol, Roger Castellote-Alvarez, Ana M. Escobar i Núria Llorca-Isern. "Superhydrophobic Coating Bioinspired on Rice Leaf: A First Attempt to Enhance Erosion Resistance Properties at Environmental Conditions with Ceramic Particles". Materials Science Forum 941 (grudzień 2018): 1874–79. http://dx.doi.org/10.4028/www.scientific.net/msf.941.1874.
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This study develops a new, facile and rapid process bioinspired on rice leaf with the aim of producing a hybrid composite coating in a first attempt to obtain a superhydrophobic coating with enhanced erosion resistance properties. Rice leaves (Oryza sativa L.) are made of hierarchical structures consisting of micropapillae and waxy nanobumps which confer to the surface a contact angle of 164° as Lotus leaf does. In particular, rice leaves accumulate amorphous silica inside and on the surface with various morphologies. This kind of silica is produced by absorbing silicates from the soil under specific conditions of temperature and pressure. The presence of biosilica in rice leaves is useful for preventing diseases or improves mechanical properties of the leaves. Single-step and two-step processes are the two strategies applied for generating a superhydrophobic coating by electrochemical deposition of ZnCl2, α-Al2O3 and lauric acid (C11H23COOH) onto commercial pure aluminum substrate. The static contact angle measured on the coating gives values of 170° and 1° for the sliding angle conducing to a coating with superhydrophobic and self-cleaning properties. Various characterization techniques are used to determine chemical and morphological structure such as FESEM, XPS or FTIR. On one hand, in morphological analysis, flower-like structure is obtained with petals thickness of 70nm corresponding to the nanostructured contribution to the system. On the other hand, chemical analysis concludes the generation of zinc laurate (Zn (C11H23COO)2) as a major compound contributing to the reduction of surface tension and increasing the superhydrophobic character of the coating as well.
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Korobkin, Laura H. "Appropriating Law in Harriet Beecher Stowe's Dred". Nineteenth-Century Literature 62, nr 3 (1.12.2007): 380–406. http://dx.doi.org/10.1525/ncl.2007.62.3.380.
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This essay investigates Harriet Beecher Stowe's interpolation of State v. Mann, a harsh 1829 North Carolina proslavery decision, into her 1856 novel Dred: A Tale of the Great Dismal Swamp. The essay argues that Stowe's use of State v. Mann continues a conversation about slavery that had been carried on through its text for many years in abolitionist writings. Bringing State v. Mann's circulation history into view shows Stowe engaging the antislavery establishment as well as the legal system, borrowing and imitating its techniques for handling proslavery materials. If her novel is infiltrated and structured by the many legal writings that it assimilates, its fictive world in turn infiltrates, interprets, and alters the significance of the writings she employs, so that proslavery legal writings are made to testify strongly against the slave system that they originally worked to maintain and enforce. Stowe's hybrid text dominates the law while smoothly assimilating it into an interpretive fictive context. Simultaneously, Stowe's typographical cues remind readers of State v. Mann's ongoing, destructive extratextual legal existence. By linking fictive context to legal content, Stowe's novel suggests that slave law must be read and interpreted as a unit that includes the individual suffering it imposes. Misreading State v. Mann as revealing its author's belief in the immorality of slavery, Stowe constructs a fictional judge who upholds slave law despite his personal beliefs. By absorbing, imitating, and besting the strategies and the reach of both legal and abolitionist writings, Dred implicitly stakes a claim for the superior power of political fiction to act in the world.
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Park, Mira, Hyeon Ku Park, Hye Kyoung Shin, Dawon Kang, Bishweshwar Pant, Hang Kim, Jin-Kyu Song i Hak Yong Kim. "Sound Absorption and Insulation Properties of a Polyurethane Foam Mixed with Electrospun Nylon-6 and Polyurethane Nanofibre Mats". Journal of Nanoscience and Nanotechnology 19, nr 6 (1.06.2019): 3558–63. http://dx.doi.org/10.1166/jnn.2019.16128.
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In recent years, noise has become a serious hazard and can have permanent biological and psychological effects on humans and other organisms in nature. Textile materials are commonly used as absorbent acoustic materials for noise reduction. This work examines the use of electrospun nylon-6 and polyurethane nanofibres (PU NFs) to improve the sound absorption and sound insulation properties of polyurethane foam. In this work, nylon-6 and polyurethane nanofibres were prepared by an electrospinning technique and were glued to a polyurethane foam. The sound absorption coefficient of the materials was measured by the impedance tube method. An impedance tube was used to measure the sound absorption and airborne sound insulation. The results showed decreased sound absorption properties, whereas the sound insulation was highly enhanced when polyurethane/nanofibre hybrids were used, as compared to the pristine polyurethane foam. Furthermore, the sound insulation properties of polyurethane foam were highly enhanced when the foam was combined with nylon-6 NFs, compared with the polyurethane foam with PU NFs. Therefore, by investigating the acoustic characteristics of electrospun nylon-6 and PU nanofibres, we believe that this study can broaden the application of electrospun nanofibres for sound pollution control.
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Cabral, Michelle Araújo, Ana Grasiela da Silva Limoeiro, Alexandre Sigrist De Martin, Carlos Eduardo Fontana, Rina Andrea Pelegrine, Carlos Eduardo da Silveira Bueno i Daniel Guimarães Pedro Rocha. "Influence of root canal moisture conditions on the bond strength of endodontic sealers to dentin". Research, Society and Development 11, nr 11 (23.08.2022): e285111133714. http://dx.doi.org/10.33448/rsd-v11i11.33714.
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Objective: To investigate the influence of intraradicular moisture conditions on the bond strength of 3 different endodontic cements in the coronal, middle, and apical thirds of the root canal. Materials and Methods: 90 single-rooted teeth were instrumented with a reciprocal R#50 file and randomly divided into 3 experimental groups: Dry group: dry canals with absorbent paper tips; Moist group: suction syringe and capillary tip coupled to a vacuum pump; Wet group: aspiration with endodontic suction. The groups were divided according to the endodontic sealer used: AH plus (Denstply), Hiflow (Brasseler) and Bio-c Sealer (Angelus). Obturation was performed using Tagger's hybrid technique with a single cone. The teeth were subjected to the "push-out" test to evaluate the bond strength of the cements. Results: Data were analyzed using the Kolgomorov-Smirnoff normal distribution test and the Mann Whitney U test to compare means within and between groups. The standard error established was 5% at a significance level of 95%. AH plus showed better results regardless of canal moisture conditions. Hiflow showed better bond strength in the dry group compared to the moist group (p=0.023) in the cervical area. Bio-C Sealer showed no statistically significant differences (p > 0.05). Conclusion: Moisture conditions affected the bond strength values of endodontic cements. The prevalence of failure moduli was mixed in all root thirds, regardless of the cement used.
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López-Rodríguez, Daniel, Barbara Micó-Vicent, Eva Bou-Belda i Pablo Díaz-García. "Reactive dye adsorption desorption and stamping by halloysite". Journal of Applied Research in Technology & Engineering 3, nr 1 (31.01.2022): 61–66. http://dx.doi.org/10.4995/jarte.2022.16583.
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The scientific community is continuously developing new methods for the recovery and purification of water, since the precious resources of our planet are increasingly scarce and we must work to save and clean our waters. One of the methods used is the use of adsorbent and absorbent materials that remove from the water those substances that are harmful to the environment are nanoclays. In this work, the effect of a nanoclay, specifically Halloysite, to adsorb reactive dyes has been used as an example of a technique. As an example of this type of coloring substances, Reactive Yellow 2 has been used, which has been subjected to the adsorbent action of the mineral, having an adsorption of 78% in the proposed experiment. Subsequently, it has undergone a desorption process by applying temperature to the dye-clay hybrid, so that later, thanks to the effect of solvents (HCL and / or NaOH), the desorption process in aqueous solution can be completed, obtaining a recovery from the dye. up to 17.67% adsorbed, which is interpreted as a very good result. At the same time, the ability to stamp the HNT has been tested once the dye has been adsorbed and used on a PES / CO textile, demonstrating the viability of this process and evaluating its results by rubbing and washing fastness tests.
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Mozaffari, Ahmad. "Synchronous self-learning Pareto strategy". International Journal of Intelligent Computing and Cybernetics 11, nr 2 (11.06.2018): 197–233. http://dx.doi.org/10.1108/ijicc-05-2017-0050.
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Purpose In recent decades, development of effective methods for optimizing a set of conflicted objective functions has been absorbing an increasing interest from researchers. This refers to the essence of real-life engineering systems and complex natural mechanisms which are generally multi-modal, non-convex and multi-criterion. Until now, several deterministic and stochastic methods have been proposed to cope with such complex systems. Advanced soft computational methods such as evolutionary games (cooperative and non-cooperative), Pareto-based techniques, fuzzy evolutionary methods, cooperative bio-inspired algorithms and neuro-evolutionary systems have effectively come to the aid of researchers to build up efficient paradigms with application to vector optimization. The paper aims to discuss this issue. Design/methodology/approach A novel hybrid algorithm called synchronous self-learning Pareto strategy (SSLPS) is presented for the sake of vector optimization. The method is the ensemble of evolutionary algorithms (EA), swarm intelligence (SI), adaptive version of self-organizing map (CSOM) and a data shuffling mechanism. EA are powerful numerical optimization algorithms capable of finding a global extreme point over a wide exploration domain. SI techniques (the swarm of bees in our case) can improve both intensification and robustness of exploration. CSOM network is an unsupervised learning methodology which learns the characteristics of non-dominated solutions and, thus, enhances the quality of the Pareto front. Findings To prove the effectiveness of the proposed method, the authors engage a set of well-known benchmark functions and some well-known rival optimization methods. Additionally, SSLPS is employed for optimal design of shape memory alloy actuator as a nonlinear multi-modal real-world engineering problem. The experiments show the acceptable potential of SSLPS for handling both numerical and engineering multi-objective problems. Originality/value To the author’s best knowledge, the proposed algorithm is among the rare multi-objective methods which fosters the use of automated unsupervised learning for increasing the intensity of Pareto front (while preserving the diversity). Also, the research evaluates the power of hybridization of SI and EA for efficient search.
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Ramos, Grazyelly Duarte, Kemily Rocha Fernandes, Willian Alencar Ribeiro i Eduardo Fernandes Marques. "Evaluation of the Influence of the type of Irrigating Solutions in Postoperative Pain and Regression of Perirradicular Injury in Teeth Obtained in Single Session and Single Cone – Clinical Case Study". International Journal of Advanced Engineering Research and Science 9, nr 11 (2022): 101–6. http://dx.doi.org/10.22161/ijaers.911.14.
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Endodontic treatment aims at the chemical and mechanical preparation of a dental element that has inflammation or pulp necrosis. During endodontic intervention, postoperative pain may develop, as well as difficulty in the regression of the periradicular lesion. Given the context, the present work is a clinical case report with the objective of evaluating whether the type of irrigating solution used in the endodontic treatment of filled teeth in a single session and single cone influences the postoperative symptomatology and regression of the periradicular lesion. This is a clinical, exploratory, qualitative and descriptive case study, where 2 patients were treated. They were divided into two groups: G1 (n:01) (irrigation with 2.5% sodium hypochlorite) and G2 (n:01) (irrigation with 2% chlorhexidine gel and saline). All dental elements were anesthetized, access surgeries were performed, initial exploration with K file # 10 or 15 was performed until the apparent length of the tooth. Instrumentation technique was performed with hand files and confirmation of working length through Root foraminal locator. Final irrigation was performed with 3 ml of 17% EDTA. The canals were dried with capillary tips, attached to a high-power suction device and with absorbent paper cones and filled, in the same session, by the Tagger Hybrid technique and restored with composite resin. Patients were followed for a period of 24h, 48h, 2, 3 and 6 months for postoperative pain assessment and periradicular lesion regression. Through the results obtained, it was noted that although both irrigating solutions are effective, it was observed that 2.5% sodium hypochlorite caused grade 3 pain according to the patient's pain scale during the first 24 hours, compared with 2% chlorhexidine gel, which had no painful symptoms at any time after completion of treatment and follow-up. In conclusion, in this study, 2.5% sodium hypochlorite may cause more postoperative pain compared to 2% chlorhexidine gel, but there was no significant difference in pain levels between the groups.
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Melnik, V. Yu. "Aflamencado practice in the contemporary piano perfoming". Problems of Interaction Between Arts, Pedagogy and the Theory and Practice of Education 56, nr 56 (10.07.2020): 266–80. http://dx.doi.org/10.34064/khnum1-56.17.
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Introduction. Flamenco is a cultural phenomenon that dates back to the 5–6th centuries. This artistic practice organically unites plastic, gesture, singing, word, instrumental play. It is difficult to determine the hierarchical relationships between these components. Each of them has its own “vocabulary”, its own laws of constructing the artistic whole, that is, its canons. In a wide artistic field, canons consider a set of certain rules, based on which creative activity is carried out, and the originality of its result is ensured by the specificity of their improvisational transformation by a particular performer. Any phenomenon that is subject to the action of a set of these specific canons acquires formal, stylistic, genre qualities that indicate the cultural and artistic environment from which they originate. Flamenco is developing dynamically and actively absorbing the experience of other musical cultures. Any phenomena that fall into the gravitational field of the flamenco canons acquire the specific traits inherent in this culture. This assimilation of alien elements is defined by the concept of aflamencado (“one that acquires the characteristic features of flamenco”). Theoretical background. Contemporary views toward flamenco culture are very different: the discrepancies are noticeable among flamenco fans, performers and scientists. The paper of Marta Wieczorec “Flamenco: Contemporary Research Dilemmas” (2018) considers disputes about the scientific issue of flamenco. She pays attention to the debatable side in science comprehension of this ethnic phenomena and its place in Spanish culture. This article also looks at the antagonism between traditional and contemporary, or, “pure” and commercial branches of flamenco. William Washbaugh in his book “Flamenco music and national identity in Spain” (2012) considers as a ambitious project the tendency to rethink Spanish national identity under the influence of the spread of flamenco music culture, its various forms. Among many contemporary musicians, he also calls Miriam Méndez. The purpose of this paper is to identify the basic strategies of aflamencado in piano art of the XX century (the ways of interaction flamenco and piano performance art of this period). Such study requires the use of musicological and performing analytical methods of scientific research, among them the methods of genre and style analysis, historical and comparative approach that are applied on this paper. The genre theory by E. Nazaykinskiy (1982) is used in this study. This theory defines genres as historically established types and kinds of musical creation, which divides according to number of criteria: by purpose (public, common, artistic function); by conditions and facilities of performing; by content and ways of creation. Aflamencado characterization using the theory of T. Cherednichenko (2002) about typologique of musical practices allowed considering different methods of adapting the flamenco ethnic elements to the academic traditions and to determine the degree of transformation of the constituent elements of the synthesis. Research results. Piano art began to embrace flamenco culture in the late XIX century. The pioneer along this path was maestro F. Pedrell and his students. One of them, І. Albenis, composed the cycles for piano “Spanish Music” No. 1 (1886), No. 2 (1889) and “Iberia” (1906–1908), where the piano pieces are enriched with the characteristic flamenco sound. The piano texture includes some elements of guitar technique: the “razguiado”, which involves repeated chords, the “punteado” – accenting performance of each sound. Melody line of Albenis’s piano works correlates with flamenco due to its generous embellishments, melismatics and hangs in detentions, which are also a projection of flamenco vocal art. The metro-rhythmic sphere of the Spanish opus by I. Albenis is often based on the typical flamenco-“compass” associated with changeable the dual and triple pulsations. Tonal and harmonic reliance on Lydian and Phrygian modes and the use of the so-called “Andalusian cadence” (t-VII-VI-D) complements the palette of flamenco expressive means of expression. These aflamencado examples have some contradictions. The nature of the pianoforte is extremely elitist and aristocratic. The “wild” and arbitrary art of Spanish Roma from the poorest regions of Andalusia, when it falls into the sound pianistic “wrapper”, is transformed significantly and acquires an academic taste. Authentic art with its oral tradition of imitation is engraved in the musical text, such fixation sends flamenco to “foreign” territory, creating grounds to believe that the cycles “Spanish suite” and “Iberia” are examples of “composer expansion” on the flamenco territory. In this example, the principles of aflamencado have a specific vector directed into the sphere of “opus- music”, and a set of tools and techniques that allow to attract the characteristic features of folk practice, with its oral and collective nature (according to T. Cherednichenko’s typology of musical practices), to creation of original, individual, non-canonical composer work. In such interaction the resources of one cultural layer allow to reach of new artistic content in other. In this sense, aflamencado acts as a means of simulating a particular object of reality in the individual perception of the author. Aflamencado in the works of contemporary composer, arranger and pianist Miriam Méndez is oriented in the opposite direction. She called her first album “Bach por Flamenco” (2005). The intertextuality of this musical experiment provides radically new content to the work that has long been canonized. J. S. Bach’s Fugue is transformed into a target. The rigid, immutable confines of the genre are being tested by the ever-changing, flamenco element. The timbre, the properties of the tools used, the built-in “cante” – all serve to update the original. The pianist, who, along with other musicians, created this genre mix, was guided, mainly, by the idea of flamenco. Conclusions. Thus, in the contemporary piano art, the aflamencado phenomenon reveals a dual nature that depends on the basic level of interaction between cultures. In one case, composer creativity engages a flamenco resource to implement authorial creative strategies. Otherwise, the composer’s work is being “prepared” for the purpose of immersing it in the primordial folk element. As a result, two fundamentally different models of pianism are formed – the academic and its flamenco variety adapted to the musical-linguistic canons. This version of piano performance in listening circles was called “flamenco-pianism”. The hybrid nature of this phenomenon now needs in further investigation.
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Salim Hamza, Sabah, Al Emran Ismail, M. Y. Yuhazri, Ahmad Hamdan Ariffin i Mohamed Thariq Hameed Sultan. "Hybridization Effect on Crashworthiness Parameters of Natural Composite". Frontiers in Materials 8 (11.02.2021). http://dx.doi.org/10.3389/fmats.2021.619245.
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The use of metallic materials in automotive industry leads to increasing fuel consumption and cost, so trends are starting to use lighter and cheaper materials. In automotive applications, fibers are used in composites because they are stronger, stiffer, and lighter than bulk materials, and they can achieve higher energy absorbing compared to metallic materials. The purpose of this work is to study the potential utilization of natural fibers in the crash energy absorbing applications. The experimental procedures (the principle of a combination of manual layup and vacuum bladder technique) were applied to search the influence of utilizing jute fiber mat on crashworthiness parameters of composite materials with other kinds of fibers such as woven glass fiber reinforced epoxy composites. The study involved corrugated composite tubes with three layers of jute and hybrid glass-jute/epoxy material have been tested in uniaxial quasi-static crush conditions at the speed 10 mm/min. The results exhibit that the tube of jute fiber was somewhat lower than synthetic fibers, but the substitution of one layer of jute fiber with one layer of glass fiber resulted in an improvement in the crashworthiness parameters. As hybrid jute-glass was used, the best result was obtained, where energy absorption and specific energy absorption are improved by 17.75% and 25.122%, respectively.
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Venkatesh, Vavilada Satya Swamy, i Rajamalla Narasimha Rao. "Influence of microwave sintering temperatures on mechanical and microstructural Behavior of Al/SiC/snail shell hybrid composite synthesized through powder metallurgy technique". Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science, 13.04.2023, 095440622311691. http://dx.doi.org/10.1177/09544062231169120.
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This study emphasizes the synthesis of hybrid aluminum composite reinforced with SiC and Snail Shell (S-Shell) particles through the powder metallurgy technique. The hybrid composite corresponding to the optimized volume fraction of SiC and Snail shell powder (Al-6%SiC-6%S-Shell) was subjected to microwave-assisted sintering (MAS) by varying the sintering temperatures from 400°C to 550°C in steps of 50°C. Results concluded that microwave-sintered composites show superior mechanical characteristics than the composites sintered through conventional sintering techniques. The maximum ultimate tensile strength (U.T.S) of 316 MPa, and compression strength of 396 MPa were obtained for microwave sintered Al-6%SiC-6%Snail shell powder composite sintered at 500°C. However, increasing the sintering temperature above 500°C leads to a reduction in U.T.S and Compression strength due to the formation of coarse grains by absorbing the microwaves at higher temperatures. The U.T.S, Compression strength and Vickers hardness of the microwave sintered Al-6%SiC-6%Snail shell powder hybrid composite sintered at 500°C was enhanced by 42.08%, 42.4%, and 35.5% compared to conventionally sintered hybrid composite. The grain size was found to be increased with an increase in microwave sintering temperature due to the enhancement in the absorption capability of the microwaves with the temperature rise. The results of this study also suggest that choosing materials with a high microwave response helps to achieve improved mechanical properties for microwave-sintered composites.
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Somani, Nalin, Navjot Singh i Nitin Kumar Gupta. "Joining and characterization of SS-430 using microwave hybrid heating technique". Journal of Engineering, Design and Technology ahead-of-print, ahead-of-print (3.02.2021). http://dx.doi.org/10.1108/jedt-08-2020-0322.
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Purpose The purpose of this paper is to based upon the joining and characterization (mechanical and metallurgical) of ferritic stainless steel (SS)-430 using a microwave hybrid heating (MHH) phenomenon. Design/methodology/approach The preliminary experiments were conducted using nickel-based powder as interface material using a domestic microwave oven at a frequency of 2.45 GHz and 900 W power for 720 s. The processed joint was metallurgically characterized by means of X-ray diffraction, Energy-dispersive X-ray spectroscopy and Field emission scanning electron microscopy. Mechanical characterization was done by means of tensile and Vickers’ microhardness testing to check the hardness and strength of the joint. Findings The metallurgical study revealed that the microstructure and formation of numerous phases of Fe2Si3 accompanied by chromium and nickel carbides. The average hardness of 359 Hv at the center of the joint and 637 Hv around the boundaries of the joint was observed. The tensile strength of the joint was observed to 471 MPa with an elongation of 9.02%. The worn surface of the joint signifies the presence of plastic deformation and it was limited due to the presence of harder phases such as Ni3Si and Ni3C. Research limitations/implications The concept of microwave joining of metals is a very challenging task as the temperature can not be controlled in the inert atmosphere of the microwave. It has been also observed that at certain elevated temperatures, the material starts absorbing the microwaves; which is unknown. So, a more intensive study is required to overcome these kinds of limitations. Practical implications MHH technique can be used to process different materials such as ceramics, composites and polymers. SS-430 joined by microwave heating is highly corrosion resistive and has wide applications in refrigerators cabinet panels, dishwasher linings, chimney liners, lashing wires, etc. Originality/value As of the author’s best knowledge, no work has been reported on the joining of SS-430 which has huge potential in the industries. Also, no work has been reported on the characterization of microwave joined SS-430.
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Kim, Chae-Hwan, Hyun-Young Kim, Jun-Ho Kim i Jaehwan Kim. "3D Printing-based Soft Auxetic Structures using PDMS-Ecoflex Hybrid". Functional Composites and Structures, 2.03.2023. http://dx.doi.org/10.1088/2631-6331/acc0cf.
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Abstract Auxetic structures with negative Poisson’s ratio have received much attention due to their attractive behavioral properties in next-generation metamaterials and robotic applications. However, until now, there has been a lack of research into using soft materials to reliably develop a largely-deformable auxetic structures. Here, we develop soft PDMS-Ecoflex auxetic structures using a 3D printing technique, leading to high fabrication reliability and repeatability. Water-soluble filaments are employed to design sacrificial mold structures that quickly dissolve in warm water. By measuring the mechanical properties and light transmittance of soft composite membranes with various mixing ratios of PDMS and Ecoflex, the intrinsic characteristics of the composite membranes are determined. The newly fabricated soft auxetic structures composed of PDMS and Ecoflex composites always exhibit negative Poisson’s ratio during stretching. The negative Poisson’s ratio of the structure is maximized when PDMS and Ecoflex have a 2:1 mixing ratio and nominal strain is less than 5 %. Advances in technology to reliably fabricate soft auxetic structures using 3D printers are believed to promote next-generation applications such as wearable sensors and energy-absorbing structures.
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Chiu, Min-Chie. "Genetic Algorithm Optimization on a Venting System With Three-Chamber Hybrid Mufflers Within a Constrained Back Pressure and Space". Journal of Vibration and Acoustics 134, nr 2 (18.01.2012). http://dx.doi.org/10.1115/1.4005220.
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Recently, research on new techniques for dissipative mufflers in dealing with the higher frequencies has been addressed. However, the shape optimization of hybrid mufflers in reducing broadband noise within a constrained space as well as a pressure-drop limit which are both concerned with the necessity of operation and system venting in practical engineering work was rarely tackled. Therefore, this study will not only analyze the sound transmission loss (STL) of a space-constrained multichamber hybrid muffler but also optimize the best design shape under a specified pressure drop. In this paper, the generalized decoupling technique and plane wave theory used to solve the coupled acoustical problem of perforated mufflers with/without sound absorbing material are presented. The four-pole system matrix used to evaluate acoustic performance is also introduced in conjunction with a genetic algorithm (GA). A numerical case for eliminating a broadband venting noise emitted from a pressure relief valve using four kinds of hybrid mufflers is also introduced. To verify the reliability of the GA optimization, optimal noise abatement for a pure tone (1000 Hz) is exemplified. Before the GA operation can be carried out, the accuracy of the mathematical models need to be checked using the experimental data. The optimal result in eliminating broadband noise reveals that the overall noise reductions with respect to various mufflers under a maximal allowable pressure drop of 100 Pa can achieve 62.6, 54.8, 32.3 and 87.8 dB. Consequently, the approach used for the optimal design of the multichamber hybrid mufflers under space and back pressure constrained conditions is indeed easy and quite effective.
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Abdullah, Abdul Hakim, Afiqah Azharia i Farrahshaida Mohd Salleh. "SOUND ABSORPTION COEFFICIENT OF NATURAL FIBRES HYBRID REINFORCED POLYESTER COMPOSITES". Jurnal Teknologi 76, nr 9 (28.09.2015). http://dx.doi.org/10.11113/jt.v76.5643.
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Natural fibres have been known of its good acoustic damping properties and therefore, these materials could be used as a sound insulation in many applications. The main purpose of this investigation is to analyze the sound absorption coefficient of sugarcane baggase fibre, banana fibre and its hybrid based composites under various fibre volume fractions. Bone dry test specimens of 10%, 20% and 30% fibre volume fraction were treated with sodium hydroxide (NaOH) prior to composites fabrication using polyester as binder. The pre-tested specimens were examined using scanning electron microscope and electronic analytical balance to analyze physical and dimension characteristic. The sound absorption frequencies were measured using by the two-microphone transfer function technique in the impedance tube that has a 100 mm diameter for low frequency and 28 mm for high frequency, 0 Hz to 4000 Hz respectively. The result indicated that in low and high frequency, the combination of different natural fibres produced better sound absorption coefficient rather than using the natural fibre as individual. The results also demonstrated that the higher amounts of fibre volume fraction are affecting frequencies broadening, hence promising better sound absorbing capacity.
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Tian, Wei, Jinyao Li, Yifan Liu, Rashad Ali, Yang Guo, Longjiang Deng, Nasir Mahmood i Xian Jian. "Atomic-Scale Layer-by-Layer Deposition of FeSiAl@ZnO@Al2O3 Hybrid with Threshold Anti-Corrosion and Ultra-High Microwave Absorption Properties in Low-Frequency Bands". Nano-Micro Letters 13, nr 1 (30.07.2021). http://dx.doi.org/10.1007/s40820-021-00678-4.
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AbstractDeveloping highly efficient magnetic microwave absorbers (MAs) is crucial, and yet challenging for anti-corrosion properties in extremely humid and salt-induced foggy environments. Herein, a dual-oxide shell of ZnO/Al2O3 as a robust barrier to FeSiAl core is introduced to mitigate corrosion resistance. The FeSiAl@ZnO@Al2O3 layer by layer hybrid structure is realized with atomic-scale precision through the atomic layer deposition technique. Owing to the unique hybrid structure, the FeSiAl@ZnO@Al2O3 exhibits record-high microwave absorbing performance in low-frequency bands covering L and S bands with a minimum reflection loss (RLmin) of -50.6 dB at 3.4 GHz. Compared with pure FeSiAl (RLmin of -13.5 dB, a bandwidth of 0.5 GHz), the RLmin value and effective bandwidth of this designed novel absorber increased up to ~ 3.7 and ~ 3 times, respectively. Furthermore, the inert ceramic dual-shells have improved 9.0 times the anti-corrosion property of FeSiAl core by multistage barriers towards corrosive medium and obstruction of the electric circuit. This is attributed to the large charge transfer resistance, increased impedance modulus |Z|0.01 Hz, and frequency time constant of FeSiAl@ZnO@Al2O3. The research demonstrates a promising platform toward the design of next-generation MAs with improved anti-corrosion properties.
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Geng, Jiao, Liye Xu, Wei Yan, Liping Shi i Min Qiu. "High-speed laser writing of structural colors for full-color inkless printing". Nature Communications 14, nr 1 (2.02.2023). http://dx.doi.org/10.1038/s41467-023-36275-9.
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AbstractIt is a formidable challenge to simultaneously achieve wide-gamut, high-resolution, high-speed while low-cost manufacturability, long-term stability, and viewing-angle independence in structural colors for practical applications. The conventional nanofabrication techniques fail to match the requirement in low-cost, large-scale and flexible manufacturing. Processing by pulsed lasers can achieve high throughput while suffering from a narrow gamut of ~15% sRGB or angle-dependent colors. Here, we demonstrate an all-in-one solution for ultrafast laser-produced structural colors on ultrathin hybrid films that comprise an absorbent dielectric TiAlN layer coating on a metallic TiN layer. Under laser irradiation, the absorption behaviours of the TiAlN-TiN hybrid films are tailored by photothermal-induced oxidation on the topmost TiAlN. The oxidized films exhibit double-resonance absorption, which is due to the non-trivial phase shifts both at the oxide-TiAlN interface, and at the TiAlN-TiN interface. By varying the accumulated laser fluence to modulate the oxidation depth, angle-robust structural colors with unprecedented large-gamut of ~90% sRGB are obtained. The highest printing speed reaches 10 cm2/s and the highest resolution exceeds 10000 dpi. The durability of the laser-printed colors is confirmed by fastness examination, including salt spray, double-85, light bleaching, and adhesion tests. These features render our technique to be competitive for industrial applications.