Double Field Research Articles

Energy storage performance and piezoelectric response of silver niobate antiferroelectric thin film

AgNbO3-based antiferroelectric materials have attracted extensive attention in energy storage due to their double polarization-electric field hysteresis loops, but they always suffer from low breakdown strength (Eb). Films with few defects and small thickness exhibit high breakdown strength, which helps to improve energy storage performance. In the present work, an AgNbO3 film with a small thickness of ∼200 nm is prepared via pulsed laser deposition, which has a dense microstructure and a small average grain size of ∼34.5 nm. The AgNbO3 film displays an antiferroelectric nature, as confirmed by the double polarization-electric field hysteresis loops at room temperature. The room temperature phase structure of the AgNbO3 film determined by the dielectric behaviour is the antiferroelectric M2 phase. Due to the small thickness and fine grain size, a high Eb of 1200 kV/cm is obtained, which boosts a recoverable energy storage density (Wrec) of 9.3 J/cm3 and an energy efficiency (η) of 63.7 % in the AgNbO3 film. In addition, Wrec exhibits good temperature stability at 30–120 °C. The AgNbO3 film shows an obvious piezoelectric response after the electric field-induced antiferroelectric-ferroelectric phase transition as confirmed by piezoresponse force microscopy. These results provide guidance for the development of AgNbO3 antiferroelectric films and devices with good energy storage performance.

Reconstruction of Type II Supergravities via O(d) × O(d) Duality Invariants

We reconstruct type II supergravities by using building blocks of O(d)×O(d) invariants. These invariants are obtained by explicitly analyzing O(d)×O(d) transformations of 10 dimensional massless fields. Similar constructions are performed by employing double field theory or generalized geometry, but we completed the reconstruction within the framework of the supergravities.

Double field of view digital sideband holography as an optimized method to measure velocity fields in a large fluid volume

Digital in-line holography is a technique that allows the measurement of the three velocity components of a three dimensional fluid flow. The application of digital in-line holography in fluid velocimetry is mainly limited by three factors: the sensor size that limits the transversal area that can be recorded, the low optical aperture that reduces the spatial resolution along the optical axis and introduces aliasing, and the noise coming from the twin image that hinders the particle position and velocity measurements. These factors do not affect in the same way when characterizing the movement of the fluid, and require different solutions.In this work we are going to show how to overcome those limitations. We applied digital sideband holography for the measurement of the particle position and velocity in a fluid volume with a cross-section twice the area allowed by the camera sensor, with magnification M = 1, and a very large the dimension along the optical axis. Digital sideband holography configuration, that keeps the simplicity of the classical in-line holographic set-up, consists of a camera, a lens and a frequency filter. This frequency filter is the key element that allows us to measure in such a large volume while maintaining spatial resolution, as well as accuracy: not only removes the twin image but also prevents the recording of unwanted frequencies that causes aliasing. We have found that the Signal to Noise Ratio depends mainly on the noise introduced by the twin image, the aliasing and the particle concentration rather than on parameters such as field of view, depth of field or the intensity of the particles.This technique is applied for the quantitative characterization of the three-dimensional flow in a lid-driven squared-sectioned cuvette. The introduction of a prism in the optical set-up allowed us to double the field of view. This is achieved by illuminating two volumes of the cuvette (22 × 22 × 100 mm3, each) with the same beam that crosses the fluid twice before reaching the camera sensor. These two fluid volumes are analyzed independently while keeping the same spatial resolution in the axial component along the whole volume than the expected for a shorter one. The experimental 3D data show a very good agreement with numerical 3D simulation, which proves the very good performance of our method.

A Double Remote Magnetic Field Synthesis Method for Reducing High-Speed MFL Signal Distortion Caused by Velocity Effect

Magnetic flux leakage (MFL) testing is coming into prominence as an inspection tool applied to pipeline evaluation. The MFL detectors are challenging to accurately evaluate pipe defects at high-speed due to velocity effects. Current methods typically require detectors to operate at low speeds or compensate for detection data offline, but they reduce detection efficiency or require sophisticated algorithms. In this article, a novel double remote magnetic field synthesis (DRMFS) method is proposed to address the issue. First, we give a thorough analysis of the influence of velocity effects on high-speed MFL signals, reinterpreting its action mechanism. Secondly, the critical parameters are optimized to improve pipe magnetization. The relationships between the sensor layout and normalized signal similarity are studied at different speeds to reduce signal distortion. Finally, the usability of the DRMFS method in reducing signal distortion and its capability in detecting deep defects are validated by measuring defect depths. Results showed synthesis signals are highly similar to static MFL signals and approximately linear with the defect depth, which could improve the detection accuracy. Our results can enable the exploration of information utilization in limited space and the establishment of a balance between detection efficiency and signal accuracy.

Hydrogen-bonded CdSe/PDI with double electric field synergism for enhanced overall water splitting performance

Interfacial and bulk-phase electric fields in hydrogen-bonded d-CdSe/PDI synergistically promote photocatalytic water splitting.

From sensing interactions to controlling the interactions: a novel approach to obtain biological transistors for specific and label-free immunosensing.

Antibody-antigen interactions are shaped by the solution pH level, ionic strength, and electric fields, if present. In biological field-effect transistors (BioFETs), the interactions take place at the sensing area in which the pH level, ionic strength and electric fields are determined by the Poisson-Boltzmann equation and the boundary conditions at the solid-solution interface and the potential applied at the solution electrode. The present study demonstrates how a BioFET solution electrode potential affects the sensing area double layer pH level, ionic strength, and electric fields and in this way shapes the biological interactions at the sensing area. We refer to this as 'active sensing'. To this end, we employed the meta-nano-channel (MNC) BioFET and demonstrate how the solution electrode can determine the antibody-antigen equilibrium constant and allows the control and tuning of the sensing performance in terms of the dynamic range and limit-of-detection. In the current work, we employed this method to demonstrate the specific and label-free sensing of Alpha-Fetoprotein (AFP) molecules from 0.5 μL drops of 1 : 100 diluted serum. AFP was measured during pregnancy as part of the prenatal screening program for fetal anomalies, chromosomal abnormalities, and abnormal placentation. We demonstrate AFP sensing with a limit-of-detection of 10.5 aM and a dynamic range of 6 orders of magnitude in concentration. Extensive control measurements are reported.

Сравнительное исследование двойного и сдвоенного электроиндукционных сферических датчиков напряженности электрического поля

The work provides a comparative study of double and dual electric field strength sensors. The comparison examined the design, technological and metrological parameters of the sensors, as well as the complexity of their measuring circuits. Research has revealed similarities in the design and technological parameters of the sensors and differences in metrological characteristics and the complexity of the measuring circuits. In terms of metrological characteristics, dual sensors are significantly superior to double ones. It has been established that a dual sensor having sensitive elements with angular dimensions 1=46,38 , and 2=90 , has a smaller error due to field inhomogeneity. The error does not exceed  ±2,76 % in the spatial measurement range 0a1. With the same error, double sensors can only be used in a limited spatial measurement range of 0a0,89. It is shown that dual sensors are superior to dual sensors in terms of metrological parameters. This indicates the advisability of their use.

Effect of outer spherical shell opening structure on the sensitivity of double spherical shell electric field sensor.

A double spherical shell (DSS) electric field sensor based on charge sensing has characteristics of small size and simple fabrication, which are appropriate for measuring complex electric field environments, but the sensitivity is low. To improve the sensitivity of the DSS electric field sensor, we theoretically analyze the effect of the diameter of the outer spherical shell opening on the sensitivity of the sensor. The sensors with outer spherical shell apertures of 2, 4, and 6mm are designed and manufactured, and the sensor's sensitivity, linearity, hysteresis, and repeatability are tested. The relative error of the sensor is evaluated by measuring the rotational characteristics of the sensor. The experimental results show that the sensor sensitivity increases with the increase in hole diameter, while the sensor has good linearity, hysteresis, and repeatability after opening the hole. The rotational characteristics experiments' results show that the sensors' relative errors with different apertures are 18, 23, and 31%, respectively. The DSS open-hole structure is more suitable for electric field measurements than the conventional flat plate structure.

Bi3O4Cl/g-C3N4/Cd0.5Zn0.5S Double Z-Scheme Heterojunction Photocatalyst for Highly Selective CO2 Reduction to Methane.

Solar-energy-driven CO2 hydrogenation is a promising strategy to alleviate the climate crisis. Methane is a desirable derivative of CO2 reduction. However, developing a photocatalyst for highly active and selective CH4 generation remains challenging. Herein, we report a double Z-scheme Bi3O4Cl/g-C3N4/Cd0.5Zn0.5S photocatalyst for efficient reduction of CO2 to CH4. In situ characterization techniques confirmed that the charge migration mechanism in Bi3O4Cl/g-C3N4/Cd0.5Zn0.5S promotes charge separation through double internal electric fields. As a result, the optimized C0.01B0.02C catalyst displayed a formation rate high up to 25.34 μmol g-1 h-1 and a selectivity of 96.52% of CH4. Moreover, the AQY of CO2 conversion on C0.01B0.02C (1.84%) was almost 41 times higher than that of the bare CN. This study provides a novel perspective to develop heterojunction photocatalysts for selective CO2 conversion to CH4.

Prioritizing Public Policy Implementation for Rural Development in a Developing Country via Multicriteria Classification

Despite the growing global interest in promoting rural development as a strategy to guarantee food security, in developing countries there are large gaps to achieve a sustainable countryside, mainly in rural areas. This research work delves into a methodological approach definition to establish the baseline for the public policy implementation and prioritize the intervention needs in the different items considered in an integral rural development public policy. The proposed methodology combines a qualitative characterization of needs and goals, a social cartography, a quantitative characterization of indicators and the use of multicriteria classification for prioritizing development policies. Eight localities with sixteen small rural settlements are taken as a research unit, to apply the proposed methodology and determine the implementation level of a public policy. The results show that a set of priority policies that both meet the authorities’ objectives and the population’s needs can be defined. Moreover, a vector of priority is proposed to define the weakest items, as a guide to local government administrations to focus efforts on interventions to achieve greater impacts on the rural community development under study. Finally, via a double field validity assessment, those strategic lines are hierarchized and analyzed regarding their potential relationships, as a social system.

Analytical modelling and reliability analysis of charge plasma-assisted Mg2Si/Si heterojunction doping less DGTFET for low-power switching applications

Fabrication of tunnel field effect transistor (TFET) confronts various challenges, one of which is random dopant fluctuation (RDF), which diminishes the benefits associated with low subthreshold swing (SS) and high ION/IOFF ratio. By conducting physics-based 2D analytical modelling, this paper proposes a magnesium silicide/silicon (Mg2Si/Si) heterojunction-based doping less double gate tunnel field effect transistor (HB-DL-DGTFET). This work utilizes the concept of charge plasma to tackle the issues of RDF. The analytical analysis in this study is based upon the determination of the center-channel potential by solving 2D Poisson’s equation, considering appropriate boundary conditions. Here, surface potential, electric field, energy bands, drain current and threshold voltage are extracted mathematically. In addition to the aforementioned parameters, several other analog performance parameters like transconductance, drain conductance, device efficiency, intrinsic gain, output resistance and channel resistance have also been studied in this context. The analytical findings have been duly validated using the ATLAS TCAD device simulator. Furthermore, this work focuses on exploring proposed device reliability through an investigation of, the influence of interface trap charges (ITC), present at the Si/SiO2 interface. The study analyses ITC's impact on analog performance and the obtained results are compared with that of conventional doping less DGTFET (C-DL-DGTFET). The simulation results reveal that HB-DL-DGTFET exhibits greater immunity against ITC. Thus, validating the potential of HB-DL-DGTFET as a superior candidate for low-power switching applications.

Generalized dualities and supergroups

Using a recently developed formulation of double field theory in superspace, the graviton, B-field, gravitini, dilatini, and Ramond-Ramond bispinor are encoded in a single generalized supervielbein. Duality transformations are encoded as orthosymplectic transformations, extending the bosonic O(D, D) duality group, and these act on all constituents of the supervielbein in an easily computable way. We first review conventional non-abelian T-duality in the Green-Schwarz superstring and describe the dual geometries in the language of double superspace. Since dualities are related to super-Killing vectors, this includes as special cases both abelian and non-abelian fermionic T-duality.We then extend this approach to include Poisson-Lie T-duality and its generalizations, including the generalized coset construction recently discussed in [arXiv:1912.11036]. As an application, we construct the supergeometries associated with the integrable λ and η deformations of the AdS5 × S5 superstring. The deformation parameters λ and η are identified with the possible one-parameter embeddings of the supergravity frame within the doubled supergeometry. In this framework, the Ramond-Ramond bispinors are directly computable purely from the algebraic data of the supergroup.

Multi-channel charge transfer in self-supporting B-g-C3Nx/Bi2S3/CdS dual S-scheme heterojunction toward enhanced photothermal-photocatalytic performance

Improving the charge separation efficiency of catalysts is a significant challenge in photocatalysis. To solve this problem, we design a three-dimensional self-supported B-g-C3Nx/Bi2S3/CdS dual S-scheme heterojunction photocatalytic system mimicking natural photosynthesis to achieve multi-channel rapid charge transfer. The dual S-scheme heterojunction induces double interface electric fields on the surface of ultra-thin B-g-C3Nx nanosheets, which can drive charge carriers to migrate directionally along multiple channels and suppress carrier recombination through spatial separation of electrons and holes. Furthermore, the three-dimensional interconnected open framework of B-g-C3Nx/Bi2S3/CdS enhances light absorption, touching off intense photothermal effects and near-field temperature rise, thereby improving the chemical reaction kinetics. Benefiting from the efficient charge separation and near-field temperature rise, the B-g-C3Nx/Bi2S3/CdS exhibits a photocatalytic oxytetracycline degradation rate of 98.7% and H2 evolution rate of 4.78 mmol g−1 h−1. This work provides new insights into the construction of efficient S-scheme photocatalysts with multiple-channel charge transfer characteristics.

Development of the Carbon Trading Market Empowered by Blockchain Characteristics

The 'double carbon' goal refers to China's commitment to reach peak carbon dioxide emissions by 2030 and achieve carbon neutrality by 2060. However, achieving a low-carbon transformation requires more innovative technologies to support it. The concept of blockchain is one of them. Blockchain technology has characteristics such characteristics and advantages are also applied to achieving carbon emission goals. In order to integrate blockchain technology into the governance of the double carbon goal, it is necessary to understand the blockchain technology and the double carbon field, which poses significant regional barriers to research. At present, most research is based on the practice of the double carbon goal, including the impact of the carbon market on the double carbon goal. In this article, the authors analyzed the impact of blockchain characteristics on the carbon market (including carbon emissions and carbon offset systems). Through its numerous strengths, blockchain technology has the potential to offer robust technical backing for the carbon trading market, thereby fostering its swift growth and innovation.

Exploring the β symmetry of supergravity

Kaluza-Klein reductions of low energy string effective actions possess a continuous O(d, d) symmetry. The non-geometric elements of this group, parameterized by a bi-vector β, are not inherited from the symmetries of the higher-dimensional theory, but constitute instead a symmetry enhancement produced by the isometries of the background. The realization of this enhancement in the parent theory was recently defined as β symmetry, a powerful tool that allows to avoid the field reparameterizations of the Kaluza-Klein procedure. In this paper we further explore this symmetry and its impact on the first order α′-corrections. We derive the β transformation rules from the frame formulation of Double Field Theory (DFT), and connect them to the corresponding rules in the Metsaev-Tseytlin and Bergshoeff-de Roo supergravity schemes. It follows from our results that β symmetry is a necessary condition for the uplift of string α′-expansions to DFT.

Tripled Structures of Algebroids in Gauged Double Field Theory

Double field theory (DFT) is an effective theory of string theory. It has a manifest symmetry of T-duality. The gauge symmetry in DFT is related to some kind of algebroid structures, and they have a doubled structure. We focus on the gauge algebra of the O(D, D+n) gauged DFT and discuss an extension of the doubled structure. The gauge algebra of the O(D, D + n) gauged DFT has been described by the F-bracket. This bracket is related to some algebroid structures. We show that algebroids defined by the twisted C-bracket in the gauged DFT are built out of a direct sum of three Lie algebroids. They exhibit a “triple”, which we call the extended double, rather than a “double” structure. We also consider the geometrical realization of these structures in a (2D + n)-dimensional manifold.

Double field theory, twistors, and integrability in 4-manifolds

The search for a geometrical understanding of dualities in string theory, in particular T-duality, has led to the development of modern T-duality covariant frameworks such as Double Field Theory, whose mathematical structure can be understood in terms of generalized geometry and, more recently, para-Hermitian geometry. In this work we apply techniques associated to this doubled geometry to four-dimensional manifolds, and we show that they are particularly well-suited to the analysis of integrability in special spacetimes, especially in connection with Penrose's twistor theory and its applications to general relativity. This shows a close relationship between some of the geometrical structures in the para-Hermitian approach to double field theory and those in algebraically special solutions to the Einstein equations. Particular results include the classification of four-dimensional, possibly complex-valued, (para-)Hermitian structures in different signatures, the Lie and Courant algebroid structures of special spacetimes, and the analysis of deformations of (para-)complex structures. We also discuss a notion of “weighted algebroids” in relation to a natural gauge freedom in the framework. Finally, we analyze the connection with two- and three-dimensional (real and complex) twistor spaces, and how the former can be understood in terms of the latter, in particular in terms of twistor families.

Effects of metal work function and gate-oxide dielectric on super high frequency performance of a non-align junction DG-MOSFET based inverter in the sub-100 nm regime: a TCAD simulation analysis

ABSTRACT This paper presents simulation analysis of an inverter made from non-aligned double gate field effect transistors (NADGFETs) in Sub-100 nm regime. The inverter consists of n-channel NADGFET and p-channel NADGFET device with a channel length of 40 nm and 50% non-alignment between gate and source/drain. The response of the inverter was tested by a combination of gate dielectric constant (k) and metal work function (ϕ). Three gate dielectrics namely, SiO2 (k = 3.9), Si3N4 (k = 7.2), HfO2 (k = 24), and three metal work function namely tungsten (ϕ = 4.5 eV), molybdenum (ϕ = 4.75 eV), gold (ϕ = 5 eV), were considered in the NADGFET inverter. This paper defines a kϕ index as characterising parameter to explore the best response from inverter configuration with minimum propagation delay, and minimum power consumption at super-high frequency. The paper proposes to analyse the NADGNFET device, in term of ION current, ION/IOFF ratio, cut-off frequency, and gate delay. And observes that low k material with moderate metal work function gives best response. The work then simulates the inverter and group the results into voltage transfer curve (VTC), transient response, and power dissipation category. The result shows that when inverter was subjected to high frequency, all the kϕ combination responds good, however when the inverter was subjected to super-high frequency, the low value of kϕ combination performs well. Thus, the result concludes that SiO2-M2 combination will be best selection to get minimum propagation delay and dynamic power dissipation by the inverter. The test strategy presented in this paper on the basis of kϕ index can serve as benchmark to test inverter device at super-high frequency.

Gravity = Yang–Mills

This essay’s title is justified by discussing a class of Yang–Mills-type theories of which standard Yang–Mills theories are special cases but which is broad enough to include gravity as a double field theory. We use the framework of homotopy algebras, where conventional Yang–Mills theory is the tensor product K⊗g of a ‘kinematic’ algebra K with a color Lie algebra g. The larger class of Yang–Mills-type theories are given by the tensor product of K with more general Lie-type algebras, of which K itself is an example, up to anomalies that can be canceled for the tensor product with a second copy K¯. Gravity is then given by K⊗K¯.

Six-pack holography for dynamic profiling of thick and extended objects by simultaneous three-wavelength phase unwrapping with doubled field of view

Dynamic holographic profiling of thick samples is limited due to the reduced field of view (FOV) of off-axis holography. We present an improved six-pack holography system for the simultaneous acquisition of six complex wavefronts in a single camera exposure from two fields of view (FOVs) and three wavelengths, for quantitative phase unwrapping of thick and extended transparent objects. By dynamically generating three synthetic wavelength quantitative phase maps for each of the two FOVs, with the longest wavelength being 6207 nm, hierarchical phase unwrapping can be used to reduce noise while maintaining the improvements in the 2π phase ambiguity due to the longer synthetic wavelength. The system was tested on a 7 μm tall PDMS microchannel and is shown to produce quantitative phase maps with 96% accuracy, while the hierarchical unwrapping reduces noise by 93%. A monolayer of live onion epidermal tissue was also successfully scanned, demonstrating the potential of the system to dynamically decrease scanning time of optically thick and extended samples.