Multilayer Design Research Articles

Fano resonance in a dolomite phase-change multilayer design for dynamically tunable omnidirectional monochromatic thermal emission.

In this Letter, we unveil the unprecedented optical phonon response of CaMg(CO3)2 (dolomite) thin film in the design of a planar ultra-narrowband mid-infrared (MIR) thermal emitter. Dolomite (DLM) is a carbonate mineral composed of calcium magnesium carbonate, which can inherently accommodate highly dispersive optical phonon modes. Utilizing strong interference in the Al-DLM bilayer, a lithography-free planar thermal emitter is realized with near-unity omnidirectional emission at a specific resonance wavelength of 7.12 µm. Further incorporation of embedded vanadium dioxide (VO2) phase change material (PCM) enables the excitation of hybrid Fano resonances with dynamic spectral tunability. The findings of this study can have multiple applications, ranging from biosensing and gas sensing to thermal emission.

Dual-Circularly Polarized Array Antenna Based on Gap Waveguide Utilizing Double-Grooved Circular Waveguide Polarizer

This article presents a dual-circularly polarized array antenna based on gap waveguide technology operating at E-band. Double-grooved circular waveguide polarizers that utilize two annulus grooves placed at 45° and 135° offset from both excitation ports are used in this work. The operating principles of the polarizer are analyzed. Multilayer design using gap waveguide is implemented on the basis of the polarizer. The antenna consists of six layers, including three layers for the feeding networks, one layer for the polarizer, one layer of back cavity, and another layer of radiating grid. A 2 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times $ </tex-math></inline-formula> 2 unit cell is proposed first and employed to realize an 8 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times $ </tex-math></inline-formula> 8 planar array. Corporate feeding networks that use compact E-plane T-junctions and H-plane T-junctions are proposed. The antenna has been fabricated and verified by measurements. The measured results of S-parameters agree well with the simulation and show that reflection coefficients are better than −10 dB for both circular polarizations (CPs) from 76 to 81 GHz. The measured isolation between the input ports is larger than 25 dB in the operating band. The far-field measurements show that the antenna has realized gain larger than 24 dBi and axial ratios less than 1.5 dB from 76 to 81 GHz at boresight direction.

Enhanced tunable dielectric properties of Ba0.6Sr0.4TiO3/PVDF composites through dual-gradient structural engineering

Materials with tunable dielectric properties were expected to be applied in electronic devices such as phased array antennas, tunable filters and phase shifters. The dielectric tunability of material greatly depends on the dielectric constant and breakdown strength. Herein, two kinds of Ba0.6Sr0.4TiO3/PVDF (BST/PVDF) composite materials with different dual-gradient structures were designed to obtain the serialized relative permittivity and improved breakdown strength. The numerical simulation based on Yamada theory confirmed that the multilayer dual-gradient structure design was beneficial to improve the dielectric constant, and the enhancement of breakdown strength was further identified by finite element simulation. The optimal composition has a high dielectric tunability of 78.27 % which is 45 % higher than the ungraded composite due to the high permittivity of 33.8 and high breakdown strength of 1900 kV/cm. The dielectric theoretical model of multilayer structure was developed by introducing the effect factor of layer number m into the Yamada model, and the calculated results are consistent with the experimental results especially m= 1.6–1.7. This work provides a new strategy to effectively improve the dielectric tunability of ceramic/polymer composite materials.

An All Silicon Carbide 3 kV/540 V Series-Resonant Converter for Electric Aircraft Systems

In this work, an all silicon carbide (SiC) series-resonant converter (SRC) design is proposed and demonstrate to achieve a single stage dc-to-dc conversion from 3 kV to 540 V (±270 V) for future electric aircraft applications. The proposed SRC consists of a neutral-point-clamped converter using 3.3-kV SiC MOSFETs on the primary side, an H-bridge converter using 900-V SiC MOSFET on the secondary side and a high-frequency (HF) transformer. The detailed design methods for the SRC power stage and the HF transformer are presented. Especially, a tradeoff between the complexity for the cooling system and the need for high power density and voltage insulation is addressed in the transformer design, leading to a novel multilayer winding structure design to enhance the insulation capability and also the mechanical robustness. The proposed bobbin design is realized using additive manufacturing. The detailed analysis and modeling of the parasitic capacitance between sections introduced by fringe electrical field are presented. To validate the effectiveness of the proposed SRC design, a 25-kW converter prototype using 3.3-kV SiC discrete devices has been developed with a peak efficiency of 99.08% achieved in experimental studies.

Triple three-phase permanent magnet synchronous motor with shaped magnets for low vibration applications

This paper presents a triple three-phase permanent magnet synchronous motor (PMSM) with shaped magnets for low vibration applications. Firstly, the features of the designed PMSM are investigated from three aspects, including triple three-phase windings, shaped magnets, and multi-layered housing. Then, the armature reaction, magnetomotive force, torque performance, and fault tolerance ability of the designed PMSM are investigated. Subsequently, the radial force of the designed PMSM with shaped magnets is studied, in which the radial force modulation effect is considered. In addition, the radial force and vibration reduction principle is elaborated in detail. The modal simulation and experiment are carried out, and the vibration reduction effect of the designed PMSM is verified by the multiphysics vibration predicted model. The result shows that the vibration can be effectively reduced by the shaped magnets and multi-layered housing design, and the output torque of the designed PMSM has been reduced insignificantly thanks to the triple three-phase windings.

System-on-chip single event effect hardening design and validation using proton irradiation

A multi-layer design is applied to mitigate single event effect (SEE) in a 28 nm System-on-Chip (SoC). It depends on asymmetric multiprocessing (AMP), redundancy and system watchdog. Irradiation tests utilized 70 and 90 MeV proton beams to examine its performance through comparative analysis. Via examining SEEs in on-chip memory (OCM), compared with the trial without applying the multi-layer design, the test results demonstrate that the adopted multi-layer design can effectively mitigate SEEs in the SoC.

Improved lead-bismuth eutectic corrosion resistance and mechanical properties of reactive gas pulse sputtered AlCrFeMoTi/(AlCrFeMoTi)N composite multilayered high-entropy alloy coatings

The (HEA/HEAN)-n multilayer coatings consisting of alternating (AlCrFeMoTi)N (top) and AlCrFeMoTi layers were specially designed and successfully deposited on 12Cr2W2Mn F/M steel substrate by reactive magnetron sputtering technology. The dependence of microstructure, mechanical properties and lead-bismuth eutectic (LBE) corrosion resistance on interlayer interface density was systematically investigated. The multilayer structure design improved the mechanical properties and high-temperature structural stability of the multilayer coatings. Furthermore, after exposed to LBE at 650 °C for 1000 h, the (HEA/HEAN)-12 multilayer coatings with optimum interlayer interface density exhibited the most optimal LBE corrosion resistance. The oxidation corrosion mechanism of the (HEA/HEAN)-n multilayer coatings were also discussed intensively.

Resonant phonon-magnon interactions in freestanding metal-ferromagnet multilayer structures

We analyze resonant magneto-elastic interactions between standing perpendicular spin wave modes (exchange magnons) and longitudinal acoustic phonon modes in free-standing hybrid metal-ferromagnet bilayer and trilayer structures. Whereas the ferromagnetic layer acts as a magnetic cavity, all metal layers control the frequencies and eigenmodes of acoustic vibrations. The here proposed design allows for achieving and tuning the spectral and spatial modes overlap between phonons and magnons that results in their strong resonant interaction. Realistic simulations for gold-nickel multilayers show that sweeping the external magnetic field should allow for observing resonantly enhanced interactions between individual magnon and phonon modes in a broad range of frequencies spanning from tens of GHz up to several hundreds of GHz, which can be finely tuned through the multilayer design. Our results would enable the systematic study and the deep understanding of resonantly enhanced magneto-elastic coupling between individual phonon and magnon modes up to frequencies of great contemporary fundamental and applied interest.

TEM study of the oxidation resistance and diffusion processes in a multilayered TiSiN/TiN(Ag) coating designed for tribological applications

This work investigates the structure evolution of a multilayered TiSiN/TiN(Ag) coating with heating, oxide scale growth, diffusion processes occurring during oxidation, and changes in the structure and chemical composition of the non-oxidized zone. The coatings have a multilayered structure with a bilayer periodic thickness of ∼40 nm. The TiN(Ag) layer consists of fcc TiN and Ag crystalline phases, where Ag nanocrystallites are homogenously distributed at the TiN grain boundaries. The TiSiN layer consists of fcc TiSiN solid solution grains and an amorphous a-SiNx phase which segregates at the TiSiN grain boundaries. In-situ hot-XRD analysis shows that the first signs of oxidation occur at 800 °C, when rutile-TiO2 starts to form. The oxidized part of the coating is Ag depleted, except the top layer terminating the structure, which contains some 1–3 nm Ag clusters. Ag diffuses towards the surface from oxidized zones. The cross-sectional analysis also shows no signs of recrystallization and structural changes, except for stress relaxation in the non-oxidized part after annealing at 800 °C. No Ag redistribution or diffusion is found in the non-oxidized part, even close to the interface with the oxide layer, which suggest effectiveness of the multilayered design to mitigate uncontrolled Ag migration towards the surface.

Functional Ionomer Gradients in Anode Catalyst Layers for Low Temperature PEM Water Electrolysis

Water electrolysis is a crucial technology for large-scale hydrogen generation, that is required for the transition to a fossil fuel-free energy system. Even though water electrolysis systems are already deployed in a limited capacity, the technology is largely constrained to liquid alkaline electrolysis. Proton exchange membrane (PEM) electrolysis could pose an alternative but it is still hindered by high investment costs, in-part due to its reliance on scarce noble-metal catalysts. Alternative structural designs of the anode catalyst layer (CL) could reduce Iridium loading of the whole system and thus accelerate its wide-spread application. In fuel cell research, it was already reported that a multi-layer design with varied ionomer content enhances performance of the CL and in-turn lowers required catalyst loading.[1,2,3]In this study, a gradient design for ionomer content is employed for anode CLs for the application in PEM water electrolysis. CLs are coated in a stacked multi-layer design via ultrasonic spray coating of Iridium/Nafion® suspensions. The target ionomer loadings (10 and 30 wt.%) are confirmed by a combination of thermo-gravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS). The coating process yields homogenously loaded reference CLs as well as through-plane graded CLs with the desired ionomer loading. Additionally, scanning electron microscopy (SEM) in conjunction with energy dispersive spectroscopy (EDS) shows equal CL thickness across all ionomer loadings and spatially differentiated Nafion® content throughout the CLs thickness. Electrochemical characterizations are carried out in an electrolysis-adapted gas diffusion electrode (GDE) half-cell setup to allow for quick examination and prototyping of produced layers. Differences in electrochemical performance of these layers can be observed with one gradient design CL showing reduced overpotential across all current densities compared to the homogenous CLs. In-particular a high ionomer loading near the membrane improves performance, most likely due to increased proton conduction to the membrane and higher available pore volume near the porous transport layer.Further analysis is performed on electrochemical studies to deepen the understanding of the role of ionomer in anodic PEM water electrolysis CLs. Particularly, the investigation of protonic and electric conductivity through the CL is of interest, because this parameter is most influenced by ionomer loading.[4]

Improveament of multiple attenuation and optimized impedance gradient for excellent multilayer microwave absorbers derived from two-dimensional metal–organic frameworks

Low-dimensional carbon matrix magnetic nanocomposites exhibit expansive prospects as lightweight microwave absorbers due to their large specific surface area and multiple attenuation characteristics. The two-dimensional (2D) flaky MOF-derived porous nanocomposites are synthesized successfully by acid etching and subsequent thermal reduction. An in-depth study of composition and flaky porous structure shows that acid etching increases multiple interfaces and carbon defects, proving beneficial for improving multiple interfacial polarization and relaxation polarization loss. In addition, the generated ferromagnetic products (Ni4N, CoFe) are beneficial in improving the magnetic loss ability. More importantly, the multilayer impedance gradient design optimizes the impedance matching characteristic. As a result, the prepared bilayer absorbing coating exhibits excellent microwave absorption properties with an effective absorption bandwidth (EAB) of 6.32 GHz at a thickness of 2.5 mm with a filling amount less than 15 wt%. When the total thickness is 3 mm, it can exhibit the widest EAB of about 7.1 GHz and the minimum reflection loss (RLmin) value of about −54.5 dB. The RCS simulation shows that the multilayer coatings exhibit good microwave scattering and absorption ability under different pitching angles, proving potential candidates for excellent microwave absorbers.

Prophetic Energy Assessment with Smart Implements in Hydroelectricity Entities Using Artificial Intelligence Algorithm

An encouraging development is the quick expansion of renewable energy extraction. Harnessing renewable energy is economically feasible at the current rate of technological advancement. Traditional energy sources, such as coal, petroleum, and hydrocarbons, which have negative effects on the environment, are coming under more social and financial pressure. Companies need more solar and wind power because this calls for a well-balanced mix of renewable resources and a higher proportion of alternative energy sources. Sustainable energy can be captured using a variety of techniques. Massive scale and small-sized are the two most prevalent techniques. No renewable energy source possesses an inherent property that restricts how it may be managed or how it can be planned to produce electricity. A number of factors have contributed to a growth in the use of alternative sources, one of which is to mitigate the effects of rising temperatures. To improve the ability to estimate renewable energy, various modeling approaches have been created. This region might use an HRES to give many sources with the inclusion of different energy sources. The inventiveness of solar and wind power and the brilliant ability of neural networks to handle complex time-series data signals have both aided in the prediction of sustainable energy. Therefore, this research will examine the numerous information models in order to determine which proposed models can provide accurate projections of renewable energy output, such as sunlight, wind, or pumped storage. In the fields of sustainable energy predictions, a number of machine learning methods, such as multilayer perceptions MLP, RNN CNN, and LSTM designs, are frequently utilized. This form of modeling uses historical data to predict potential values and can predict short-term patterns in solar and wind generation.

Cost-effective Programmable Logic Arrays Using Multilayer Structures of Decoders in QCA Framework

The emerging nanotechnology paradigm, Quantum Dot Cellular Automata (QCA) in particular, is gaining a wide recognition due to its high speed, nano feature size and considerably low power consumption. The QCA architecture not only provide potential alternative for Complementary Metal Oxide Semiconductor (CMOS) circuits but its multilayer topology facilitates an added benefit of cost efficacy and immunity towards random interference. Moreover, design of programmable logic devices in QCA is vital to promote the multi-utility and resiliency of the computing circuits. This paper presents the multilayer designs of 2×4 and 3×8 decoder circuits in QCA framework with 55.1% and 51.17% better cost efficiency respectively, over the earlier reported designs. The presented 3×8 decoder circuit is further utilized to implement Programmable Logic Array (PLA) to realize Boolean functions of adder and subtractor. The presented circuits are cost effective and showcase the significance of programmable devices in nano-computing.

Attendance as a Service: A multi-layered system design in attendance applications for Covid-19

During Covid-19, there has been a requirement of a distributed architecture for contact-less and available smart application which deploys in personal mobile devices. However; the single-layer architecture of the other similar applications in the literature, has not been met the user requirements according to the preliminary tests. Moreover, the conventional ones offer a high-cost architecture. To overcome these challenges; Software as a service (SaaS) has been more preferred for the integration of distributed applications in the cloud market in a cost-efficient way. Therefore; we propose an Attendance as a Service; i.e. new multi-layered system which includes such technologies as QR code, face recognition and fingerprint to meet the reliability and contact-less performing. In the performance evaluation, the proposed system serves with lower delay and higher scalability when compared to conventional ones. It has been observed that the multi-layered structure provides 8 milliseconds of gain in delay compared to the traditional one and overcomes the students' inability to attendance due to server density.

Enhanced Thermoelectric Performance of ZnO-Based Thin Films via Interface Engineering

Zinc oxide (ZnO) is a potential thermoelectric material with good chemical and thermal stability as well as an excellent Seebeck coefficient. However, the extremely low carrier concentration brings poor electrical transport properties. Although Gallium (Ga) doping could increase the carrier concentration of ZnO film, its thermoelectric performance is still limited due to the deteriorated Seebeck coefficient and enhanced thermal conductivity. Interface engineering is an effective strategy to decouple electron-phonon interaction for thermoelectric materials. Thus, in this work, GZO (Ga-doped ZnO)/NAZO (Ni, Al co-doped ZnO) multilayer films were designed to further improve the thermoelectric properties of GZO films. It was found that GZO/NAZO multilayer films possessed better electrical conductivity, which was attributed to the increased carrier concentration and Hall mobility. Meanwhile, benefiting from the energy filtering that occurred at GZO/NAZO interfaces, the density of states effective mass increased, resulting in comparable Seebeck coefficient values. Ultimately, an enhanced power factor value of 313 μW m−1 K−2 was achieved in the GZO/NAZO multilayer film, which is almost 46% larger than that of GZO film. This work provides a paradigm to optimize the thermoelectric performance of oxide films and other thermoelectric systems by multilayer structure design with coherent interfaces.

Application of Human-Computer Interaction System in Regional Tourism Competitiveness Analysis under IoT Background.

With the continuous development of Internet of Things technology, this technology is not limited to the laboratory but is more and more applied in the process of commercialization. Large-scale machine communication is one of the three most important scenarios for 5G applications. Its features include larger uplink access, smaller data packets, higher device energy consumption requirements, lower device transmission speed, higher latency, and bursty communication. With the development of the Internet of Things in the 5G era, interpersonal interaction experience has been further optimized and welcomed by the market and adopt Qt/embedded multilayer menu design mode to improve our computer system interaction to facilitate the operation and Maintenance system. The software function of the human-computer interaction system has reached the expected result. By constructing the application of a human-computer interaction system in the analysis of regional tourism competitiveness, we analyze the temporal and spatial changes of tourism competitiveness in four major economic regions in China and combine multiple linear regression and geographic detector models to analyze China's tourism competitiveness. On this basis, we propose to further enhance the tourism competitiveness of areas with weak tourism development infrastructure and encourage potential tourism development areas to complement each other with high-quality resources between regions.

Long-acting PFI-2 small molecule release and multilayer scaffold design achieve extensive new formation of complex periodontal tissues with unprecedented fidelity

The faithful engineering of complex human tissues such as the bone/soft tissue/mineralized tissue interface in periodontal tissues requires innovative molecular cues in conjunction with tailored scaffolds. To address the loss of periodontal bone and connective tissues following periodontal disease, we have generated a polydopamine and collagen coated electrospun PLGA-PCL (PP) scaffold enriched with the small molecule mediator PFI-2 (PP-PFI-pDA-COL-PFI). In vitro 3D studies using PDL progenitors revealed that the PP-PFI-pDA-COL-PFI scaffold substantially enhanced Alizarin Red staining, increased Ca/P ratios 4-fold, and stimulated cell proliferation more than 12-fold compared to PP-controls, suggestive of its potential for mineralized tissue engineering. When applied in our experimental periodontitis model, the PP-PFI-pDA-COL-PFI scaffold resulted in a substantial 34% reduction in alveolar bone defect height, a 25% root-length gain in periodontal attachment, and the formation of highly ordered regenerated acellular cementum twice as thick as in controls. Explaining the mechanism of PFI-2 mineralized tissue regeneration in periodontal tissues, PFI-2 inhibited SETD7-mediated β-Catenin protein methylation and increased β-Catenin nuclear localization. Together, dual-level PFI-2 incorporation into a degradable, dopamine/collagen coated PLGA/PCL scaffold backbone resulted in the regeneration of the tripartite periodontal complex with unprecedented fidelity, including periodontal attachment and new formation of mineralized tissues in inflamed periodontal environments.

Optimize multilayer matching layer design for tone-burst underwater acoustic transducers.

In this study, a theoretical model has been constructed to address the optimization of matching layers for tone burst excitation underwater acoustic transducers and to investigate the functional mechanism change of matching layers. Single, double, and triple matching layers are attached to piezoelectric composite plates, and tone burst signals with a different number of burst-cycles are applied. Acoustic pressure function (Sp) and acoustic pressure transient response (PTR) are compared among these transducers. The results demonstrated that when the cycle number M ≤ 2, more matching layers lead to shorter ringdown with similar PTR amplitude. Since the objective is for better axial resolution, three matching layers have noticeable advantage, whereas for the case of M > 5, far detection distance is the main objective, and more matching layers caused the decrease in PTR amplitude. Besides, matching layers become part of the resonance structure; they do not serve as a transmission medium anymore. Therefore, the transducer with single matching is optimal for the long tone burst excitation. For the case of 2-5 cycle excitation, one may use double matching layers, which has a balance between the transmitting voltage response amplitude and bandwidth. With the increase in M, the role of matching layers changes from a bridging transmission medium to amplifying vibration velocity and introducing additional vibration modes to broaden the bandwidth.

Recent trends and challenges in developing boride and carbide-based solar absorbers for concentrated solar power

Concentrating solar power technology has gained increased attention as a source for clean energy. However, because of low power density, it requires large areas and materials with high photothermal conversion efficiency, to harness solar energy. The solar receiver coated with solar selective material plays a critical role in efficiently converting solar energy to useful power. Because of the moderate solar selective nature and excellent thermal properties, significant efforts are currently being invested on the use of ultra-high temperature ceramics as solar selective absorbers. This literature survey presents a critical review of the research and development of early transition metal boride and carbide-based solar selective absorbers, both in bulk and tandem coating formats. In particular, we have emphasized the use of transition metal borides and carbides as intrinsic absorbers as bulk or even exploiting a multilayer design approach to improve the absorptance in the solar spectrum region. One of the key aspects is to introduce a gradient in optical constants (refractive index, extinction coefficient) to tailor high absorptance and low emissivity in tandem absorber coatings, with insightful understanding into microstructure-optical property correlation. The challenges in developing tandem solar absorbers with long-term thermal stability at mid to high temperature window in different working atmosphere are emphasized to spur the development of next generation spectrally-selective solar absorbers.

Characterization of high impedance of multilayer coplanar waveguide transmission line design for integration with nanodevices

Terahertz technology has recently attracted the attention of the researchers due to its wide range of applications such as security and military, biomedicine and health care, astronomy and biology. There are many scrutinized research papers among the terahertz applications with nanodevices such as self-switching devices. They need monolithic microwave integrated circuits for integration. It is evident that the system impedance of transmission lines is 50 Ω. However, the main limitation of self-switching diodes is high level of impedance in megaohms which is a huge value and is not so easy to implement. Paper focuses on the design and simulation of the coplanar waveguide transmission line structures with higher impedance by applying multilayer technology for the integration with self-switching diodes. Using multilayer technology in design allows wide range of impedances. Two approaches have been targeted such that meets all the requirements of integration with nanodevice. First approach is a widening the gap of the polyimide dielectric layers used in the fabrication of these components. Several design structures have been considered such as positioning the location of signal and grounds contacts with respect to the position of the dielectric layers. As the result the highest characteristic impedance of about 90 Ω was achieved at operating frequency of 110 GHz. Secondly, novel coplanar waveguide transmission line structure was investigated where the V – shape structure was joined with the signal elevated structure. The terahertz application research may effect on high data transmission rate of no less than 10 GBit/s and thereby in increase of traffic volume.