Simple Configuration Research Articles

Contemporary Approaches in Evolving Language Models

This article provides a comprehensive survey of contemporary language modeling approaches within the realm of natural language processing (NLP) tasks. This paper conducts an analytical exploration of diverse methodologies employed in the creation of language models. This exploration encompasses the architecture, training processes, and optimization strategies inherent in these models. The detailed discussion covers various models ranging from traditional n-gram and hidden Markov models to state-of-the-art neural network approaches such as BERT, GPT, LLAMA, and Bard. This article delves into different modifications and enhancements applied to both standard and neural network architectures for constructing language models. Special attention is given to addressing challenges specific to agglutinative languages within the context of developing language models for various NLP tasks, particularly for Arabic and Turkish. The research highlights that contemporary transformer-based methods demonstrate results comparable to those achieved by traditional methods employing Hidden Markov Models. These transformer-based approaches boast simpler configurations and exhibit faster performance during both training and analysis. An integral component of the article is the examination of popular and actively evolving libraries and tools essential for constructing language models. Notable tools such as NLTK, TensorFlow, PyTorch, and Gensim are reviewed, with a comparative analysis considering their simplicity and accessibility for implementing diverse language models. The aim is to provide readers with insights into the landscape of contemporary language modeling methodologies and the tools available for their implementation.

Analytical Models for the Time Response of a Microstrip Line with Two Additional Symmetrical Conductors on Top under Different Boundary Conditions at Their Ends

Introduction. Protection of radio electronic equipment (REA) against various electromagnetic interferences is an important aspect of electromagnetic capability. Among interferences for REA, ultra-short pulses of picosecond and nanosecond ranges represent the highest danger due to their high voltage, short duration, and wide spectrum. One effective protection measure consists in the use of bandpass devices based on modal decomposition, such as modal filters (MF). This requires an analysis of distortion of the temporal response of bandpass devices, which is usually carried out numerically. However, even for simple configurations, this approach is associated with high computational costs. Yet simple analytical time-response models are acceptable in some cases. In the initial design stages, such models are extremely useful in providing a preliminary solution and a rapid assessment of response distortions. Therefore, comparison of time responses obtained by numerical methods and analytical models appears an important research task. Aim. To compare the time responses obtained by quasi-static analysis and analytical models. Materials and methods. Analytical models for computing time responses based on a modal analysis technique were considered. A quasi-static modeling of a microstrip line (MSL) with two additional symmetrical conductors on top in the TALGAT system was carried out. Results. Analytical models are proposed for an MSL with two additional symmetrical conductors on top taking different boundary conditions at their ends into account. The accuracy and reliability of the proposed models are verified by comparing the time responses obtained by quasi-static analysis and the proposed models. The results obtained showed good agreement. Conclusion. It is shown that an MSL with two additional symmetrical conductors on top can be used as an MF under different boundary conditions at the ends of these conductors. The proposed models allow the shape and amplitude of the response to be estimated with acceptable accuracy, reducing time and computational costs.

Controlled Synthesis of a High‐Mobility Bi3O2.5Se2 Semiconductor by Oxidation of Bi2Se3 for Fast and Highly Sensitive Photodetectors

AbstractThe search of new high‐mobility two‐dimensional (2D) semiconductors is crucial for the development of next‐generation photodetectors, since current photodetectors based on single 2D semiconductors usually cannot simultaneously own ultrafast response rate and ultrahigh sensitivity. Here, using a facial method of sequentially oxidizing Bi2Se3 at optimal O content, a series of bismuth oxyselenide semiconductors (Bi3O2.5Se2, Bi2O2Se, Bi2SeO5) with appealing electronic applications are successfully synthesized. The crystal and band structures of a superlattice‐free Bi3O2.5Se2 phase are resolved by 3D electron diffraction and density functional theory calculations, showing a unique non‐neutral layered structure, moderate band gap, and small effective mass. More importantly, the concept of Bi2Se3 + O2 can be extended to synthesize the superlattice‐free Bi3O2.5Se2 ultrathin films by chemical vapor deposition, whose room‐temperature mobility can be as high as ≈150 cm2 V−1 s−1 based on Hall measurements. The ultrathin Bi3O2.5Se2 photodetectors with a simple device configuration simultaneously own ultrafast response time (≈31 µs), ultrahigh responsivity (≈8 × 104 A/W), and large detectivity (≈8 × 1013 Jones). This work not only introduces a facile way to regulate the phase in the bismuth oxyselenide family, but also provides an alternative candidate for ultrafast and ultrasensitive photodetectors.

Design of vortex-based cavitation devices/reactors: Influence of aspect ratio, number of inlets and shape

Vortex-based hydrodynamic cavitation devices are being used in a wide range of applications. However, adequate information on the design of such devices is not available. In this work, we have computationally investigated the influence of key design parameters such as the aspect ratio of the vortex chamber, the number of tangential inlets and the shape of the device on resulting flow characteristics and cavitation. Experiments were carried out to validate key findings from the computational studies. These investigations revealed that the aspect ratio of the vortex chamber as six may be considered as optimum. The performance of single and multiple inlet devices was found to be comparable at the same pressure drop (that is at same energy consumption per m3). Scale-up with a geometric similarity led to a reduction in the extent of cavitation for same energy consumption per m3. For facilitating scale-out option, an attempt was made to simplify the configuration of the vortex-based cavitation device. Computational results indicated that the cavitation performance of simplified configuration was not significantly inferior. A case of the formation of liquid–liquid emulsion was taken as a test case for evaluation of a modified cavitation device based on the present investigations. The droplet size distributions of emulsions generated by both the devices indicate that the proposed simplified configuration, which may facilitate fabrication and offer integrated scale-out options, performs almost at par with a complex configuration. The presented results will be useful for optimising designs of vortex-based hydrodynamic cavitation devices/ reactors.

Using extruded circular multi-injectors to improve fuel jet mixing and distribution in combustion chambers of scramjet

An extensive investigation of multi-nozzle with various heights is done for enhancing the fuel mixing and distribution in supersonic combustion chambers of scramjets by using Computational Fluid Dynamics. Fuel injection and mixing play a crucial role in many industries, including automotive. This study examines the mechanism of hydrogen fuel jet mixing when injected through a multi-nozzle with varying heights in the combustion chamber of a scramjet. The impact of different injector height configurations on supersonic cross-flow is analyzed through computational fluid dynamics, and the flow and fuel mixing are evaluated to determine the most efficient fuel injection setup. A comparison is made between the proposed multi-jet configurations and simple multijet configurations to identify the primary hydrodynamic and mixing benefits of multi-jet configuration with different heights. The findings indicate that the use of multi-jet injectors with different heights decreases the circulation factor and improves fuel mixing downstream of four jets by 40 %.

Reconfigurable Metasurface: Enabling Tunable Reflection in 6G Wireless Communications.

With the continuous advancement of technology, there is an increasing need for innovative solutions that can handle complex applications such as haptic communications, Internet of Things for smart cities, automation, and manufacturing. One technology that has received much attention is the phase reconfigurable metasurface for reconfigurable intelligent surfaces (RISs). The RIS demands low-power consumption, simple configuration, angular stability, and polarization insensitivity. The use of phase reconfigurable metasurfaces provides benefits such as low cost, low power consumption, and improved communication coverage and quality. This article introduces a reconfigurable combined-loop metasurface that can effectively manipulate phase reflection. This is achieved by incorporating four PIN diodes between two meta-atoms of a 2 × 2 periodic array within a single-layer metallic structure. By controlling the state of the PIN diodes, which can be switched into 16 different states, the metasurface can achieve various phase reflections. The proposed structure has validated a 32× 32 metasurface through numerical simulations and experiments that exhibit promising results, demonstrating its potential for use in 6G applications.

Modeling adhesion and aerodynamic removal of particles and spores from substrates

During launch operations, mission critical hardware and materials are encapsulated in a fairing prior to deployment. Depressurization can induce particle removal from fairing walls and redistribute them onto the payload. This poses serious challenges for current and future missions. This includes organic, inorganic, and biological material which can contaminate the surrounding environment. Given the risks associated with these events, efforts have been made to perform predictive simulations of particle contamination and redistribution. This work outlines the modeling efforts related to adhesion and aerodynamic removal of particles for prediction of redistribution in fairing environments. Physics-based models for adhesion and removal mechanisms are discussed. This includes the application of existing particle and spore adhesion models. Validation is performed for simplified canonical flow configurations. Future work regarding model improvements and extensions to large scale simulations is also discussed.

The directional flow generated by peristalsis in perivascular networks-Theoretical and numerical reduced-order descriptions.

Directional fluid flow in perivascular spaces surrounding cerebral arteries is hypothesized to play a key role in brain solute transport and clearance. While various drivers for a pulsatile flow, such as cardiac or respiratory pulsations, are well quantified, the question remains as to which mechanisms could induce a directional flow within physiological regimes. To address this question, we develop theoretical and numerical reduced-order models to quantify the directional (net) flow induceable by peristaltic pumping in periarterial networks. Each periarterial element is modeled as a slender annular space bounded internally by a circular tube supporting a periodic traveling (peristaltic) wave. Under reasonable assumptions of a small Reynolds number flow, small radii, and small-amplitude peristaltic waves, we use lubrication theory and regular perturbation methods to derive theoretical expressions for the directional net flow and pressure distribution in the perivascular network. The reduced model is used to derive closed-form analytical expressions for the net flow for simple network configurations of interest, including single elements, two elements in tandem, and a three element bifurcation, with results compared with numerical predictions. In particular, we provide a computable theoretical estimate of the net flow induced by peristaltic motion in perivascular networks as a function of physiological parameters, notably, wave length, frequency, amplitude, and perivascular dimensions. Quantifying the maximal net flow for specific physiological regimes, we find that vasomotion may induce net pial periarterial flow velocities on the order of a few to tens of m/s and that sleep-related changes in vasomotion pulsatility may drive a threefold flow increase.

A simple and low‐cost open dynamic chamber for the versatile determination of methane emissions from aquatic surfaces

AbstractMethane (CH4) emissions from aquatic ecosystems require accurate monitoring in the context of climate change. Among the several methods for CH4 flux measurement, open dynamic chambers (ODC) are a reliable option. This method consists of a floating chamber through which a carrier gas is constantly flowing, providing accurate flux measurement with high temporal resolution. However, this method requires expensive and heavy CH4 analyzers with high sensitivity, as well as a carrier gas system that comprises a gas cylinder and a gas flow controller, among other components. This system involves significant weight and cost challenges, limiting method implementation in certain settings and hindering its wider adoption. To address these limitations, we developed a simplified ODC configuration using atmospheric air as the carrier gas and a light and relatively less expensive detector. We applied this method to a 450‐ha urban lake with CH4 emissions ranging from moderate diffusive to high ebullitive fluxes. Concurrent measurements using a high‐sensitivity CH4 analyzer allowed us to compare the accuracy of the simplified ODC method and to assess its advantages and disadvantages. Results show that our method provides accurate CH4 flux measurements with a spatial resolution comparable to high‐sensitivity analyzers. This offers a more cost‐effective, straightforward, and lightweight alternative to high‐sensitivity detectors and carrier gas systems, simplifying ODC deployment in aquatic ecosystems.

Time Delay Signature Extraction of Optical-Feedback-Induced Chaos With Reservoir Computing

The time delay signature is a crucial secure key for chaos communication using optical feedback semiconductor lasers. Herein, we propose a single node-based photonic reservoir computing method for extracting the time delay signature of optical-feedback-induced chaos. Through drawing the phase diagram of the chaotic time series and its delayed copies, we transform the time delay signature into the shape feature of the obtained two-dimensional image. After training the optimized photonic reservoir with these two-dimensional images, we numerically demonstrate that our method can achieve an overall extraction accuracy rate of 97.3% for different optical feedback semiconductor lasers. Considering its good performance and simple configuration, we believe that this single node-based photonic reservoir computing offers a hardware-friendly solution for time delay signature extraction.

MEMS SWITCH BASED ON CANTILEVER WITH INCREASED CONTACT FORCE

MEMS switches are of significant interest for promising radio-electronic systems, but have not yet found widespread use due to the low reliability of microcontacts. The switch develops low contact force, which results in high and unstable contact resistance. The force is usually increased by using electrodes with complex shapes and large areas, but a simple and compact configuration is preferable. This work presents a key based on a 50 µm long cantilever. For the first time, a method for selecting the vertical dimensions of a product is described, increasing the clamping force to values ​​​​in excess of 100 μN, necessary for reliable operation of the contacts. Test samples were manufactured and tested, and the performance characteristics were compared with the calculation results.

All-Optical Modulation Format Conversions from PAM4 to QPSK and 16QAM Using Silicon-Rich Nitride Waveguides

Quadrature phase-shift keying (QPSK) and 16-quadrature amplitude modulation (16QAM) formats are deployed in inter-data center networks where high transmission capacity and spectral efficiency are required. However, in intra-data center networks, a four-level pulse amplitude modulation (PAM4) format is deployed to satisfy the requirements for a simple and low-cost transceiver configuration. For the seamless and effective connection of such heterogeneous networks without an optical-electrical-optical conversion, an all-optical modulation format conversion technique is required. In this paper, we propose all-optical PAM4 to QPSK and 16QAM modulation format conversions using silicon-rich nitride waveguides. The successful conversions from 50-Gbps-class PAM4 signals to 50-Gbps-class QPSK and 100-Gbps-class 16QAM signals are demonstrated via numerical simulations.

Comparative evaluation by two different hybrid power flow controller topologies of transient stability of machine system connected to wind-PV sources

The Hybrid Power Flow Controller (HPFC) has a simple design configuration, where the upgrading of the line functionality and controller can be performed in stages. This paper applies two HPFC configurations to a multi-machine power network. The first HPFC is a combination of two static synchronous series compensators (SSSC) connected in series, and a Static Var compensator (SVC). The second one consists of two shunt Static synchronous compensators (STATCOM) connected through a Thyristor controlled series compensator (TCSC), across a coupling transformer in a common DC link. The HPFC topologies are tested with a multi-machine power network with faults, in the presence of solar and wind energy sources. The overall model is simulated using SimPowerSystems toolbox and the performance of the two HPFC topologies is compared under various operating conditions. The comparison of simulation results shows that the second HPFC gives a better view than the first in analyzing the power system transient stability.

Windage Loss Models for Enclosed Cylindrical Flows Under S-CO2 Condition

Abstract A supercritical CO2 (S-CO2) Brayton cycle is expected to have high compactness, simple configuration, and competitive efficiency. These advantages originated from CO2 nonideal gas properties near the critical point. However, the strong real gas effect makes the design challenging. Among components, turbomachinery is most affected by the real gas effects of S-CO2. In order to obtain accurate design of the turbomachinery, accurate loss models are needed. Windage loss is one of the external losses that determines the motor load and is responsible for heat generation due to friction. The overall turbomachinery efficiency is greatly affected by the windage loss especially in an S-CO2 power cycle due to high fluid density and high rotational speed. Therefore, an accurate windage loss model that can reflect the real gas effect of CO2 near the critical point is essential to obtain accurate design of the turbomachinery as well as the power cycle. In this paper, existing windage loss models are compared under S-CO2 conditions first, and the applicability of each model is evaluated. The comparison is to understand how much turbomachinery performance uncertainty can be expected due to the windage loss models and to suggest the way to improve the models.

Superior supercapacitive performance of molybdenum sulfide/reduced graphene oxide composite

Hydrothermal strategy was used to grow molybdenum sulfide (MoS2) micro flower-like structures reinforced reduced graphene oxide (rGO) for supercapacitor (SC) application. Morphological and structural analyses confirmed the well-distribution of MoS2 on rGO sheets. Despite using lithium sulfate (Li2SO4) as a relatively high-voltage window electrolyte, potassium iodide (KI) was incorporated for sturdy iodide/iodine redox interaction. Thus, the fabricated symmetric SCs result achieved superior power density (Pd) of ∼36 kW/kg and exceptionally high energy density (Ed) of 132.9 Wh/kg at 10 and 0.1 A/g, respectively. The maximum estimated specific capacitance (Cs) was 357 F/g for optimum KI ratio. Additionally, SC possesses more than 99 % of retention value after applying 8000 cycles at 10 A/g. These findings implies MoS2/rGO composite and Li2SO4/KI mixed electrolyte configuration as a simple but efficient SC configuration for high energy, power and lifetime.

Numerical simulation of the laminar boundary layer flow over a flat plate

Understanding the dynamic and thermal characteristics of the boundary layer (BL) flows is an essential step toward the best design and operational conditions for many engineering devices. Flow characteristics within the boundary layer are governed by two forces that are in a mutual race to dominate the flow, the viscous and inertial forces. The state of the flow is determined by the relative domination of these two forces inside the boundary layer zone. Theoretical solutions for many BL flow types existed since the beginning of the 20th century. Theoretical solutions are strictly possible for simple boundary layer flow configurations within the laminar range and before flow separation occurs. For practical situations where boundary layer flow problems are prescribed with complex flow configurations, CFD techniques represent the most suitable approach to tackle such types of flows. In this study, the laminar boundary layer flow over a flat plate has been solved numerically leading to a detailed analysis of the boundary layer flow with accuracy comparable to that of the theoretical solution

The influence of NAPL distribution on the transport of PFOS in Co-contaminated media

The objective of this research was to examine the influence of nonuniform NAPL distribution and hydraulic-conductivity heterogeneity on the retention and transport of PFAS. Two-dimensional flow cell experiments were conducted to investigate the impact of NAPL configuration on PFOS retention. Two simplified NAPL configurations were used, one with decane present as residual and the other with greater-than-residual (pool) NAPL saturation. The measured and predicted retardation factors were 1.7 and 1.6 for the residual-NAPL flow cell. The fractions of retention associated with solid-phase sorption, NAPL-water interfacial adsorption, and NAPL absorption were 0.56, 0.43, and 0.1, respectively. The measured retardation factor was 1.4 for the pool-NAPL flow cell. Notably, the predicted retardation factor assuming no contribution from NAPL-water interfacial adsorption was 1.5. Comparison of the two values indicates a minimal contribution of NAPL-water interfacial adsorption to transport, which is attributed to the impact of by-pass flow effects that limited contact of PFOS with the NAPL present within the pool. Mathematical-model simulations were conducted to examine the impact of heterogeneity on PFOS transport in model NAPL-contaminated heterogeneous source zones. The results demonstrated that the impact of NAPL-water interface adsorption on PFAS transport in NAPL-contaminated source zones can be influenced by the magnitude of hydraulic-conductivity heterogeneity.

A Novel Quad-Band Branched Monopole Antenna with a Filter Suppressing Higher Order Modes

This paper proposes a novel quad-band branched monopole antenna with a filter. The proposed antenna has a simple configuration in which branch-elements are added to a basic configuration consisting of a mast and dielectric wires. The antenna is characterized by performances such as wideband impedance matching, gain stabilization, and gain enhancement. Wideband impedance characteristics satisfying the voltage standing ratio of less than 2 are obtained by exciting a parallel resonance at the lowest band and multi-resonance at high bands. The filter suppressing higher order modes is used for gain stabilization, so that averaged gains above 5 dBi are obtained at the quad-band. The antenna has a high gain of 11.1 dBi because the branch-elements work as an end-fire array antenna at the highest band. Furthermore, it is clarified that an operating frequency is switched by using a variable bandpass filter at the lowest band. Last, a scale model of the antenna is fabricated and measured, then the effectiveness of the proposed antenna is demonstrated.

Random Laser Operating at Near 1.67 µM Based on Bismuth-Doped Artificial Rayleigh Fiber

A narrow-linewidth bismuth-doped fiber laser (BDFL) with the random cavity and operational wavelength at 1.67 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$µ$</tex-math></inline-formula> m was demonstrated. The laser cavity was formed by an array of weakly reflecting fiber Bragg gratings inscribed in the active fiber core directly during the fiber drawing process. Taking into account the performed analysis of optical and laser properties, the viability of this approach as applied to Bi-doped fibers with high-GeO <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$_{2}$</tex-math></inline-formula> -SiO <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$_{2}$</tex-math></inline-formula> glass core is shown, even despite the high sensitivity of bismuth active centers (BACs) to laser irradiation, i.e. processing does not lead to the destruction of the BACs. The maximum output power of the developed BDFL in a simple linear configuration with the use of 200 m-long bismuth-doped active fiber was <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\sim$</tex-math></inline-formula> 20 mW at room temperature when pumped by Er-Yb fiber laser at a wavelength of 1568 nm and the total power of 450 mW. The achieved width of the laser emission line was narrower than 0.02 nm. We studied the laser behavior in various configurations, and it was revealed that the laser wavelength can vary within the spectral range of 1.669–1.674 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$µ$</tex-math></inline-formula> m in dependence on the length and the ambient temperature of the active fiber. It was most likely caused by inhomogeneous distribution of the written gratings structures along the active fiber length that was induced due to the peculiarities of the used active fiber, namely, a significant core ellipticity. In addition, we demonstrated the possibility of the output power scalability of this type of lasers by using a homemade Bi-doped fiber power amplifier. As a result, the optical power of the random BDFL was increased up to 240 mW.

Energy transfer and vortex structures: visualizing the incompressible turbulent energy cascade

The transfer of kinetic energy from large to small scales is a hallmark of turbulent flows. Yet, a precise mechanistic description of this transfer, which is expected to occur via an energy cascade, is still missing. Several conceptually simple configurations with vortex tubes have been proposed as a testing ground to understand the energy cascade. Here, we focus on incompressible flows and compare the energy transfer occurring in a statistically steady homogeneous isotropic turbulent (HIT) flow with the generation of fine-scale motions in configurations involving vortex tubes. We start by filtering the velocity field in bands of wavenumbers distributed logarithmically, which allows us to study energy transfer in Fourier space and also visualize the energy cascade in real space. In the case of a statistically steady HIT flow at a moderate Reynolds number, our numerical results do not reveal any significant correlation between regions of intense energy transfers and vorticity or strain, filtered in corresponding wavenumber bands, nor any simple self-similar process. In comparison, in the transient turbulent flow obtained from the interaction between two antiparallel vortex tubes, we observe a qualitatively simpler organization of the intense structures, as well as of the energy transfer. However, the correlations between energy transfer and strain are small, and point to complicated dynamics of energy transfer. By imposing a structure at large scales consisting of antiparallel vortex tubes in a statistically steady flow, we observed a picture qualitatively similar to what was observed for the transient flow, but the energy transfer statistics do not reproduce the type of triadic interactions seen in HIT. These results indicate that the specific properties of the large-scale vortical structures affect the way energy is transferred, and may not be fully representative of HIT.