Stable Mode Research Articles

An extended variational method for the resistive wall mode in toroidal plasma confinement devices

The external-kink stability of a toroidal plasma surrounded by a rigid resistive wall is investigated. The well-known analysis of Haney and Freidberg is rigorously extended to allow for a wall that is sufficiently thick that the thin-shell approximation does not necessarily hold. A generalized Haney–Freidberg formula for the growth-rate of the resistive wall mode is obtained. Thick-wall effects do not change the marginal stability point of the mode but introduce an interesting asymmetry between growing and decaying modes. Growing modes have growth-rates that exceed those predicted by the original Haney–Freidberg formula. On the other hand, decaying modes have decay-rates that are less than those predicted by the original formula. The well-known Hu–Betti formula for the rotational stabilization of the resistive wall mode is also generalized to take thick-wall effects into account. Increasing wall thickness facilitates the rotational stabilization of the mode, because it decreases the critical toroidal electromagnetic torque that the wall must exert on the plasma. On the other hand, the real frequency of the mode at the marginal stability point increases with increasing wall thickness.

Feed system tracking receive/transmit shaped Cassegrain antenna C/K bands

Background. The need to create, space communication stations based on mobile carriers, for example, on ships, requires the use of multi-band reflector antennas irradiating systems that ensure the combination of not only channels for receiving and transmitting high-frequency signals, but also direction-finding channels for constructing a monopulse tracking system. Aim. Study of the possibility of creating an irradiation system that ensures the combination of reception and transmission of signals in the multi-band reflector antenna in spaced ranges with frequency bands C(Rx) – 21 %, C(Tx) – 16 % and K(Rx) – 21 %, with the implementation of a monopulse angular automatic tracking system in both receiving ranges. Methods. Development of a three-band irradiation system that ensures the implementation of automatic tracking in both receiving ranges. Analysis of the characteristics of a three-band irradiation system that ensures the implementation of reception and automatic tracking in both receiving ranges. Results. Development of a three-band irradiation system that ensures the implementation of automatic tracking in both receiving ranges. Analysis of the characteristics of a three-band irradiation system that ensures the implementation of reception and automatic tracking in both receiving ranges. Conclusion. The irradiation system of the multi-band reflector antenna for mirrors with profiled surfaces is proposed, with the implementation of combined signal reception in the C(Rx) and K(Rx) frequency ranges with a 21 % band and signal transmission in the C(Tx) frequency range with a 16% band, and the formation of partial RPs in both receiving ranges for the implementation of a monopulse angular tracking system. The following characteristics of the irradiation system are implemented: cross-polarization isolation of more than 30 dB, the formation of identical partial RPs and a stable tracking mode based on signals from onboard repeaters in communication systems with frequency reuse.

An Adaptive Approach in Polymer-Drug Nanoparticle Engineering using Slanted Electrohydrodynamic Needles and Horizontal Spraying Planes.

The present study focuses on the adaptive development of a key peripheral component of conventional electrohydrodynamic atomisation (EHDA) systems, namely spraying needles (also referred to as nozzles or spinnerets). Needle geometry and planar alignment are often overlooked. To explore potential impact, curcumin-loaded polylactic-co-glycolic acid (PLGA) and methoxypolyethylene glycol amine (PEG)-based nanoparticles were fabricated. To elucidate these technological aspects, a horizontal electrospraying needle regime was adapted, and three formulations containing different polymeric ratios of PLGA: PEG (50:50, 75:25, and 25:75) were prepared and utilised. Furthermore, processing head tip geometries e.g.blunt (a flat needle exit) or slanted (a 45° inclination angle), were subjected to various flow rates (5 µL-100 µL). Successful engineering of curcumin-loaded polymeric nanoparticles (< 150nm) was observed. In-silico analysis demonstrated stable properties of curcumin, PEG and PLGA (molecular docking studies) and fluid flow direction towardsthe Taylor-Cone (also known as the stable jet mode), was shownby the assessment of fluid dynamics simulations in various needle outlets. Curcumin-loaded nanoparticles were characterised using an array of methods including Scanning electron microscopy, Differential scanning calorimetry, Fourier transform infrared spectroscopy, X-ray diffraction, as well as their contact angles, encapsulation efficiencies and finally release patterns. The discrepancy when spraying with blunt and angled needles was evidenced by electron micrographs and deposition patterns. Spraying plumes utilising slanted needles enhanced particle collection efficiency and distribution of resultant atomised structures. In addition to needle design, fine-tuning the applied voltage and flow rate impacted the electrospraying process. The coefficient of variation was calculated as 30.5% and 25.6% for blunt and angled needle outlets, respectively, presenting improved particle uniformity with the employment of angled needle tips (8-G needle at 25 µL). The interplay of processing parameters with the utilisation of a slanted exit at a capillary optimised the spray pattern and formation of desired nanoparticulates. These demonstrate great applicability for controlled deposition and up-scaling processes in the pharmaceutical industry. These advances elaborate on EHDA processes, indicating a more cost-effective and scalable approach for industrial applications, facilitating the generation of a diverse range of particle systems in a controlled and more uniform fashion.

A Computational Perspective into Binding Mechanism of a potent FAK Inhibitor as Anticancer Drug Candidate: Insights from Molecular Dynamics Simulations

Focal adhesion kinase (FAK) is an important non-receptor tyrosine kinase (nRTK) with crucial role in primary cell functions. Fundamental cellular processes, such as migration, adhesion, proliferation, and survival, are regulated by FAK. The tumorigenesis of FAK is very important since it is overexpressed in advanced cancers, causes malignant features and induces cancer metastasis. The available evidence proposes FAK as a promising target for cancer therapy. At the moment, there are no FAK inhibitors (FAKIs) in the market but several small molecule FAKIs have been developed and a few of them entered into clinical studies as anticancer agents. In spite of these achievements, development of selective and potent FAKIs may be partly hampered by the lack of crystallographic or structural data. This limitation could be resolved through proposing robust ligand–protein binding models to design new FAKIs. GSK2256098 is a small molecule ATP-competitive FAKI that undergoes clinical trials as a monotherapy or in combination with other medications against advanced solid tumors. GSK2256098 have been proven to be a selective and potent agent (IC[Formula: see text] 0.4 nM) with respect to other clinical candidates. With regard to appropriate characteristics, this molecule is particularly amenable for performing computational modeling studies. In this study, we try to propose an applicable binding model of GSK2256098 inside the FAK kinase domain. For this purpose, molecular docking, all-atom 200-ns molecular dynamics simulations and free-energy-calculation methods were applied as consecutive modeling techniques. Atomic insight and dynamic evolution of the system were used to attain a stable binding mode and infer chemical interactions of GSK2256098 inside the kinase domain of FAK. Although complementary investigations need to be conducted, obtained results may offer a structural basis for the development of potent and selective FAKIs.

Linear stability analysis of oblique Couette–Poiseuille flows

We perform a detailed numerical study of modal and non-modal stability in oblique Couette–Poiseuille profiles, which are among the simplest examples of three-dimensional boundary layers. Through a comparison with the Orr–Sommerfeld operator for the aligned case, we show how an effective wall speed succinctly characterizes modal stability. Large-scale parameter sweeps reveal that the misalignment between the pressure gradient and wall motion is, in general, destabilizing. For flows that are sufficiently oblique, the instability is found to depend exclusively on the direction of wall motion and not on its speed, a conclusion supported, in part, by the perturbation energy budget and the evolution of the critical layers. Closed forms for the critical parameters in this regime are derived using a simple analysis. From a non-modal perspective, pseudoresonance is examined through the resolvent and the $\epsilon$ -pseudospectra. An analysis of the unforced initial value problem shows that the maximum energy gain is highly dependent on both the magnitude and direction of the wall velocity. However, the strongest amplification is always achieved for configurations that are only weakly skewed. Finally, the optimal perturbations appear to develop via a lift-up effect enhanced by an Orr-like mechanism, the latter driven by cross-flow shear.

Key feature identification of internal kink mode using machine learning

The internal kink mode is one of the crucial factors affecting the stability of magnetically confined fusion devices. This paper explores the key features influencing the growth rate of internal kink modes using machine learning techniques such as Random Forest, Extreme Gradient Boosting (XGboost), Permutation, and SHapley Additive exPlanations (SHAP). We conduct an in-depth analysis of the significant physical mechanisms by which these key features impact the growth rate of internal kink modes. Numerical simulation data were used to train high-precision machine learning models, namely Random Forest and XGBoost, which achieved coefficients of determination values of 95.07% and 94.57%, respectively, demonstrating their capability to accurately predict the growth rate of internal kink modes. Based on these models, key feature analysis was systematically performed with Permutation and SHAP methods. The results indicate that resistance, pressure at the magnetic axis, viscosity, and plasma rotation are the primary features influencing the growth rate of internal kink modes. Specifically, resistance affects the evolution of internal kink modes by altering current distribution and magnetic field structure; pressure at the magnetic axis impacts the driving force of internal kink modes through the pressure gradient directly related to plasma stability; viscosity modifies the dynamic behavior of internal kink modes by regulating plasma flow; and plasma rotation introduces additional shear forces, affecting the stability and growth rate of internal kink modes. This paper describes the mechanisms by which these four key features influence the growth rate of internal kink modes, providing essential theoretical insights into the behavior of internal kink modes in magnetically confined fusion devices.

Evaporitic–lacustrine mudstone laminites and prodelta mudlobes – continuity and change in the Hartmann's Valley interval, Murray formation, Gale crater, Mars

ABSTRACTThe sedimentary fill of Gale crater on Mars is dominated by lacustrine strata that are the focus of investigations into surface processes, climate change and habitability early in the planet's history. This study focuses on the lower part of the explored portion of the Murray formation on Aeolis Mons (Mount Sharp) in the Pahrump Hills and Hartmann's Valley field areas. At Pahrump Hills, sedimentary features and geochemical attributes of exposed mudstones suggest accumulation in an underfilled lake basin in which lake levels, shorelines and salinities fluctuated greatly at various temporal scales. The immediately superjacent stratigraphic interval, designated by the rover team as the Hartmann's Valley member, has previously been interpreted as an aeolian‐deposited sandstone interval. This fresh examination of all available data, however, suggests that the Hartmann's Valley member is strongly dominated by the same mudstone facies that compose most of the underlying Pahrump Hills member. The one novel facies element encountered in the Hartmann's Valley member are undulose bedded to convex bodies of mudstone that are oriented roughly north–south, suggestive of sediment supply from a northern fluvial source. Mudstones analogous in scale and character to these undulose mudstones occur on Earth in multiple modern and ancient lacustrine successions, and are related to deposition of prodelta mud lobes. The mudstones of the Hartmann's Valley member record a continuation of the underfilled evaporitive lake system proposed previously for the underlying Pahrump Hills member but with somewhat more variable environmental conditions. Hartmann's Valley mudstones contain more abundant matrix CaSO4, suggesting more severe evaporitic conditions, whereas the interbedded undulose bedded mudstones signify intermittent freshening and buildout of mud‐dominated deltas into the lake. The textural similarities between Pahrump Hills and Hartmann's Valley strata suggest that the Gale lacustrine system operated at a stable depositional mode with similar environmental parameters during both stratigraphic intervals.

Predicting the onset of Alzheimer’s disease and related dementia using electronic health records: findings from the cache county study on memory in aging (1995–2008)

IntroductionClinical notes, biomarkers, and neuroimaging have proven valuable in dementia prediction models. Whether commonly available structured clinical data can predict dementia is an emerging area of research. We aimed to predict gold-standard, research-based diagnoses of dementia including Alzheimer’s disease (AD) and/or Alzheimer’s disease related dementias (ADRD), in addition to ICD-based AD and/or ADRD diagnoses, in a well-phenotyped, population-based cohort using a machine learning approach.MethodsAdministrative healthcare data (k = 163 diagnostic features), in addition to census/vital record sociodemographic data (k = 6 features), were linked to the Cache County Study (CCS, 1995–2008).ResultsAmong successfully linked UPDB-CCS participants (n = 4206), 522 (12.4%) had incident dementia (AD alone, AD comorbid with ADRD, or ADRD alone) as per the CCS “gold standard” assessments. Random Forest models, with a 1-year prediction window, achieved the best performance with an Area Under the Curve (AUC) of 0.67. Accuracy declined for dementia subtypes: AD/ADRD (AUC = 0.65); ADRD (AUC = 0.49). Accuracy improved when using ICD-based dementia diagnoses (AUC = 0.77).DiscussionCommonly available structured clinical data (without labs, notes, or prescription information) demonstrate modest ability to predict “gold-standard” research-based AD/ADRD diagnoses, corroborated by prior research. Using ICD diagnostic codes to identify dementia as done in the majority of machine learning dementia prediction models, as compared to “gold-standard” dementia diagnoses, can result in higher accuracy, but whether these models are predicting true dementia warrants further research.

Initial results from neoclassical tearing mode stabilization experiment in KSTAR high normalized beta plasmas

Abstract Active stabilization of neoclassical tearing modes (NTMs) is critical for high beta plasma operation in the KSTAR tokamak. In recent device operation, an experiment was conducted to develop a m/n = 2/1 NTM stabilization in high normalized beta (βN) plasmas having βN &gt; 3 by using electron cyclotron current drive (ECCD). The experiment is designed to first demonstrate the direct mode stabilization effect of the device EC system by varying the ECCD deposition location around the mode rational surface to prepare for future NTM stabilization in KSTAR using feedback schemes. In the experiment, the toroidal magnetic field strength, BT, is reduced to 1.5–1.6 T to create a highly localized ECCD profile on a large island width expected to produce a high stabilization effect. To align the ECCD with the mode, BT is varied between discharges by keeping the EC wave injection angles fixed to move the current deposition location across the q = 2 mode rational surface in ~1 cm steps along the plasma midplane. The result shows a prompt reduction of the mode amplitude by ~60% with a partial recovery of the loss of stored energy when the ECCD with 0.7 MW power is applied promptly after the mode onset at BT = 1.54 T. This abrupt reduction of the mode amplitude is significantly weaker or disappears in other discharges having slightly different BT in which the ECCD is deposited a few centimeters away. This result indicates a direct interaction between the driven EC current and the radially localized island structure first observed in the device. The EC ray-tracing analysis using the TORAY code shows that the applied EC-driven current aligns with the mode rational surface when the mode amplitude is observed to decrease. The stability of the observed 2/1 NTM is examined by constructing the modified Rutherford equation (MRE). The calculated EC power requirement for complete mode stabilization by assuming perfect alignment of ECCD on the mode is 0.8-1.7 MW by considering the uncertainties in the equation. This MRE-computed mode stability agrees with the experiment. The result projects that the present KSTAR EC system can stabilize the 2/1 NTM disrupting high βN plasmas, and provides the requirement of the mode-ECCD alignment for complete mode stabilization in future experiments in which an accurate alignment is planned to be made by feedback schemes being developed.&amp;#xD;

First principles investigation of structural, elastic, thermoelectric, electronic and optical properties XH3 (X=Ac, La) for hydrogen storage

Efficient hydrogen storage is essential for its use as an energy source. Considering the various methods, hydrogen storage in solid materials shows great promise but requires further research. This study employs density functional theory using the Wien2k, with the LSDA method to determine the stability of this storage mode, and LSDA + mBJ to calculate the electronic, optical, and thermoelectric properties of AcH3 and LaH3. The electronic properties reveal that XH3 (X = Ac, La) exhibits a semiconducting nature with indirect energy gaps in both cases. The analysis of hydrogen storage properties determined the gravimetric hydrogen storage capacities for AcH3 and LaH3 to be 1.297 and 2.086 wt%, respectively. Calculations of the elastic constants validated the mechanical stability of these compounds. Thermoelectric characteristics, including electrical and thermal conductivity, Seebeck coefficient, electronic specific heat capacity, and Pauli magnetic susceptibility, have been evaluated, highlighting their p-type characteristics. The figure of merit indicates their potential for thermoelectric devices. Gravimetric ratios suggest significant hydrogen storage capacity, which could contribute to various transportation and energy applications.

Effect of the dissipative states of non-ideal second-type superconductors on their current-carrying capacity

The influence of the dissipative states of non-ideal second-type superconductors on their current-carrying capacity is investigated. The study performed is based on the numerical solution of non-stationary Maxwell and Fourier equations with different features of the non-linear rise of their I-V characteristics. First, the power equation of the I-V characteristic with various n-values was used to examine the states of superconductors that occur when the I-V characteristic continuously increases. Second, the obtained results are compared with the results of computer experiments simulating the thermo-electrodynamic states of superconductors when the electric field is not present in their I-V characteristics in the subcritical current range. A piecewise linear I-V equation describes such idealized modes. The results of the simulations indicate that a superconductor's ability to carry the transport current drops as the n-value decreases. Accordingly, the maximum transport current (quench current) flowing stably through a superconductor with an idealized I-V characteristic are always higher than the corresponding value calculated for superconductor with the same critical current but with a continuously increasing I-V characteristic. Moreover, a deterioration in cooling conditions or an increase in the current charging rate will also lead to a reduction in the current-carrying capacity of non-ideal second-type superconductors. The non-trivial temperature change of superconductors during formation of stable modes should necessarily be taken into account in experiments to investigate the voltage-current characteristics of superconductors, their current-carrying capacity, and loss theory.

Quasi-continuous exhaust operational space

Abstract The IPED predictive pedestal code has been used to determine the critical gradients for the onset of 1) separatrix ballooning modes and 2) global peeling-ballooning modes as a function of plasma shaping. This results in a scaling of the onset threshold of separatrix ballooning modes as a function of elongation and triangularity αedge,crit = 0.64κ2.2(1+δ)0.9, while the critical gradient for global peeling-balloonig modes increases as αedge,crit 1.5. This implies that operational space for a ballooning unstable separatrix and stable peeling-ballooning modes exists at sufficiently high shaping. Applying a collisional broadnening based scaling of the separatrix gradients allows the critical separatrix density, required to drive the separatrix ballooning mode, to be derived from global plasma parameters for any operational scenario on any device. Evaluations for ASDEX Upgrade, JET, and the ITER 15 MA baseline plasma predict critical separatrix densities of 0.3-0.4 nGW for QCE access, making the QCE an attractive operational scenario for fusion devices.

УНІВЕРСАЛЬНА МАТЕМАТИЧНА МОДЕЛЬ АВТОНОМНОГО АСИНХРОННОГО ГЕНЕРАТОРА З КОНДЕНСАТОРНИМ САМОЗБУДЖЕННЯМ

A universal mathematical model of an autonomous asynchronous generator with capacitor self-excitation in retarded phase coordinates is proposed, taking into account the electromagnetic connections between the windings of the stator and rotor phases, saturation of the main magnetic circuit, and active power losses in the magnetic circuit elements. The model provides an opportunity to analyze stable periodic modes and transient electromagnetic and electromechanical processes in autonomous power supply systems with arbitrary switching schemes of its elements and asynchronous generators. The model provides the possibility of taking into account the residual magnetization of the magnetic circuit of an asynchronous generator and the change in rotor speed during the course of the self-excitation process of an asynchronous generator with a grounded neutral of the stator winding and an asymmetric load. References 10, figures 2.

Bioactive phenolic contents of Scorzonera ketzkhowelii Sosn. ex Grossh. (Asteraceae) with comprehensive in vitro and in silico studies

This study explores the antioxidant, anti-inflammatory, and anticholinesterase properties of extracts from the natural plant Scorzonera ketzkhowelii for the first time. Additionally, it focuses on isolating phenolic compounds from the ethyl acetate sub-extract, elucidating their structures, and investigating their in-silico bioactivities. Twelve phenolic compounds were isolated and characterized from the ethyl acetate sub-extracts, including hydrangenol (1), 4-hydroxybenzaldehyde (2), luteolin (3), esculin (4), 3-O-caffeoylquinic acid ethyl ester (5), 3-O-caffeoylquinic acid methyl ester (6), kaempferol 3-O-β-glucopyranoside (7), quercetin 3-O-α-arabinopyranoside (8), 3,5-di-O-caffeoylquinic acid ethyl ester (9), thunberginol F 7-O-β-D-glucopyranoside (10), hydrangeic acid 4′-O-β-D-glucopyranoside (11), and 3-O-caffeoylquinic acid (12). The ethyl acetate sub-extracts from both aerial and subaerial parts demonstrated exceptional radical scavenging activity. Moreover, all fractions exhibited potent inhibition against COX-I and COX-II enzymes, with notable inhibitory effects observed in the ethyl acetate and dichloromethane sub-extracts against AChE. Additionally, the inhibitory effects of these compounds were assessed against various biological targets, including TNFα, COX-I, COX-II, human CYP450, and hAChE, through molecular docking studies. According to the molecular docking and dynamics studies, compound 9 emerged as particularly noteworthy across all complexes, exhibiting stable binding modes and promising interactions with key residues involved in inhibition.

Broadband conversion between high-order angular modes based on double-sided exposure long-period fiber grating

Broadband high-order mode converters play a fundamental and crucial role in mode division multiplexing systems. Unfortunately, there have been no reports on achieving broadband mutual conversion between high-order modes using long-period fiber gratings (LPFGs). In this paper, based on the concept of “stepwise” progressive conversion (SPC), a double-sided exposure fabrication method of LPFGs to achieve broadband mutual conversion between high-order modes is proposed and demonstrated. Based on the proposed method, broadband mode conversion from LP11 to LP21, from LP21 to LP31 and from LP31 to LP41 with low insertion loss are achieved by utilizing low exposure power and shortened device lengths. The 10 dB bandwidths of the three converters are measured to be 80 nm, 110 nm, and 90 nm, respectively, and their insertion losses are all less than 0.2 dB. Theoretically, this method can achieve broadband conversion of even higher-order modes, providing a novel solution for the fabrication of stable broadband mode converters. More generally, such mode converters can convert between any two modes and are essential for building advanced MDM networks that require routing and mode switching.

Benchmark experimental study on cavitating flow around Clark-Y 11.7 % hydrofoil at various angles of attack under controlled levels of dissolved air

The present research aims to study cavitating flow around a CLARK-Y 11.7 % hydrofoil with variable angles of attack (α) while maintaining controlled levels of dissolved air in the operating fluid, which is water. A series of experiments were conducted using a water tunnel facility, where the cavitation characteristics were measured and observed using sensors and high-speed imaging techniques. The variables studied in the present work are cavitation number (1 ≤ σ ≤ 2.2) and angle of attack (α = 4°, 6°, 8°, 10°, and 12°), with dissolved air levels (DAL) in the range of 9.3 ppm to 13.1 ppm. The dimensionless cavity length decreases significantly with increasing values of σ/α, indicating an inverse relationship where higher cavitation numbers or lower angles of attack result in shorter cavities. The cavity length follows a power-law scaling relationship, with the empirical equation Lmax/C=4.78×σ/α−0.76.Increasing the angle of attack transitions the cavitation nature from stable (Mode I) to dynamic (Mode II) and highly oscillating (Mode III). Larger cavities result in lower Strouhal numbers, which indicates reduced vortex shedding activity. The relationship between the Strouhal number and the normalized cavitation number σ/α is characterized by the power-law equation St=0.041×σ/α0.3. The pressure coefficient at the leading-edge increases with the angle of attack at low cavitation numbers, while higher cavitation numbers lead to greater pressure coefficient differences between the leading and trailing edges.The present study offers an extensive dataset and empirical correlations that may serve as a benchmark framework, which facilitates the validation of computational and experimental models of cavitating flow under similar conditions.

Failure mechanism and crashworthiness optimization of variable stiffness nested origami crash box

In recent years, the study of the crashworthiness of lightweight and efficient thin-walled energy-absorbing structures has received increasing attention. In this work, 3D printing technology was adopted to create a nested origami crash box with stiffness variation, which was made of short carbon fiber reinforced nylon material. The structure effectively inhibits the development of failure behavior of short carbon fiber-reinforced nylon origami crash box due to material brittleness. The quasi-static compression experiment results indicate that compared to origami crash box, nested origami crash box improves by 40% in specific energy absorption and 50% in crash force efficiency, while the initial peak crushing force remains unchanged. The effects of three key geometrical parameters, namely dihedral angle, distance between tubes, and height difference on the damage mechanism of the nested origami crash box are discussed in detail using the finite element method, and the response surface model combined with the non-dominated sorting genetic algorithm II is used for multi-objective optimization. In this work, the concepts of origami theory and nested systems are integrated for the first time, aiming to achieve a stable and efficient energy-absorbing deformation mode by precisely modulating the stress transfer path of the structure and its stiffness. This work provides new ideas for the design and fabrication of novel lightweight energy-absorption boxes.

Design and architecting of a broadband bullet-diamond shaped integrated frequency selective meta-surface absorber for aero-stealth platform.

The work report on architecture of integrated frequency selective meta-surface (IFSMS) absorbers for aerospace stealth applications. Fabricated IFSMS comprised of a pattern metasurface integrated with dielectric interlayer and conducting ground. Initially, a supercell (2 × 2-unit cell: 24 × 24 mm2) was designed with a fourfold topological symmetry. Supercell produces impedances (R), inductances (L), and capacitances (C) in tune with design on its interaction with microwave. RC performance was tested at variable incident transverse electric/magnetic (TE/TM) modes over, Θ, 0°-60° and at the normal incidence (TE), against a planer, clockwise rotation over, Φ, 0°-90°. The mode stability and rotational invariance was analyzed for displacement current- and power-density distributions. The impedance behavior and phase reversal S11 reflection coefficient studies revealed the emergence of mid-band Fabry-Perot mode distinguishing LC behavior of the circuit. The meta-pattern was manufactured by mask lithography using a customized resistive micro-carbon ink and imprinted onto dielectric/ground tile (dimension: 30 × 30 cm2). Structure-property relationship of the ink material was investigated using SEM, XRD, FTIR, UV-visible spectroscopy to reveled surface properties of imprinted material. The absorber was subjected to the free space measurements over C (4-8), X (8-12), and Ku (12-18GHz) bands, including pristine interlayer dielectrics. The simulated and experimental RC data was found to be in excellent agreement. The proposed IFSMS design is a potential candidate for the stealth application.

MHD stability analysis against pressure and current-driven modes in the SMall Aspect Ratio Tokamak

Abstract Linear magnetohydrodynamic (MHD) simulations for the SMall Aspect Ratio Tokamak (SMART) have been carried out for the first time, for both positive (PT) and negative triangularity (NT) shaped plasmas using the MARS-F code. The MHD stability of projected SMART plasmas against internal kinks, infernal modes and edge peeling-ballooning modes have been analyzed for a wide range of realistic equilibria. A stabilization of internal kinks and infernal modes is observed when increasing the safety factor profile and reducing plasma beta. PT shaped plasmas are more stable against both internal kinks and infernal modes than their counterpart NT shaped plasmas. Toroidal flows have little impact on the MHD stability of the internal kinks, but they have a strong stabilizing effect on infernal modes, which can be further mitigated in NT shaped plasmas. The MHD stability of peeling-ballooning modes is reduced in NT shaped plasmas, as observed in conventional tokamaks.

Wave patterns of the coupled nonlinear Schrödinger equations in photonic crystal fibers with four-wave mixing

Abstract In this paper, we examine the behavior of modulation instability within photonic crystals. The model employed is the coherent coupled nonlinear Schrödinger equation, incorporating weak birefringence and four-wave mixing, which arises at the edge of the optical mode. The linear analysis is used to derive the modulation instability spectrum. Throughout the modulation instability spectrum, we identify both stable and unstable modes, thereby confirming the breakdown of the plane wave. For certain four-wave mixing parameters, the amplitude of the modulation instability spectrum and its bandwidths expand, creating an opening for localized structures to emerge. Another aspect of this study has been demonstrated in normal and anomalous dispersion regimes where an increasing initial amplitude of the plane wave is fulfilled. Specifically, numerical simulations highlight the occurrence of Benjamin-Feir instability, where wave patterns emerge under the influence of four-wave mixing. Additionally, solitonic waves are generated, demonstrating the presence of Akhmediev breathers and other modulated structures, confirming that photonic crystals with four-wave mixing are conducive to these formations. The findings from this study could inform future research in the development of nonlinear photonic waveguides.