Propagation Constant Research Articles (Page 1)

This research was conducted to investigate aquifer protective capacity for groundwater exploration using Darzarrok parameters in the Federal Polytechnic Mubi, Adamawa State, Northeastern Nigeria, in order to determine aquifer thickness (H), aquifer resistivity (r), Conductivity d =1/r, longitudinal conductance (S = dh), and transverse resistivity (R = hr) of each VES point; to determine transmissivity (Tr = kh) and diagnostic parameters (Dp = Tr/R) of each VES point; and to classify protective capacity ratings of vertical electrical soundings (VES) points into moderate, weak, good, and poor. The data obtained in the field were subjected to qualitative and quantitative analysis that reveals the numbers of layers and the resistivity values of each Vertical Electrical Sounding (VES). Dar Zarrouk parameters of each VES point were analyzed and determined. The protective capacity rating of VES points VES A, VES B, VES C, VES D, VES E, and VES F was Moderate, Weak, Good, Moderate, Moderate, and Good. VES points A, B, C, D, and E were promising for groundwater exploration (hand dug well), while VES point B is not promising for groundwater exploration. For future research, there is a need to employ an integrated geophysical survey within the study area to detect the hidden targets of promising groundwater potential zones.

Abstract The plasma around a reentry spacecraft causes the charged particles to interact with the electromagnetic waves emitted by the on-board antennas, and the vehicle experiences radio communication difficulties. A proposed way to mitigate the radio blackout is the magnetic field alleviation technique that consists of superimposing a magnetic field onto the flow, converting the plasma into an anisotropic medium, and changing its refractive index. The applied magnetic field leads to the creation of an extraordinary wave that can propagate for plasma frequencies higher than the radio signal frequency. In this work, a probe containing a cryogenically-cooled high-temperature superconducting magnet is used to study the effect of an applied magnetic field on the plasma flow and on the radio signal propagation, in the VKI Plasmatron facility. The magnetized plasma is characterized by optical emission spectroscopy, stagnation heat flux, and dynamic pressure measurements. The experimental radio signal measurements are conducted using conical horn antennas, operating at frequencies in the K $$_\text{a}$$ a -band. An antenna is placed inside of the magnetic probe, transmitting toward a stagnant air plasma flow. The applied magnetic field causes an increase of the flow temperature, leading to an augmentation of the plasma frequency and stagnation heat flux, due to the Hall effect. No significant effects are observed in the signal transmission and attenuation, while the signal reflection trend is consistent with the variation of magnetic field strength, and plasma and collision frequencies. The dependency of the Faraday rotation with the magnetic field and its direction is observed. While a clear demonstration of the magnetic window is not conclusively observed in the transmission parameters, the behavior of the reflection coefficient shows that the radio blackout mitigation is feasible at optimal combinations of flow ionization.

Contrasting roles of farm categories in the enzootic circulation of bovine brucellosis through cattle trade in Paraguay.

Abstract We present the first measurements of the energy spectra of the isotopes of Galactic cosmic rays (GCRs) with nuclear charge Z = 1–14 in the very local interstellar medium (VLISM). We also update our previously published energy spectra of GCR elements in the VLISM from Z = 1–28 for a new longer time period of observations, 2013 January 1 through 2021 December 31. The observations are from the Cosmic Ray Subsystem on the Voyager 1 (V1) spacecraft and cover the Z -dependent energy range from ∼3 to 661 MeV nuc −1 . The data are fit to eight models using the GCR propagation code GalProp , which differ by having four options for fragmentation and two options for production cross sections. The models are all plain diffusion models with injection spectra as power laws in rigidity, where the propagation parameters and the injection power-law index are the same for all species, and derived self-consistently and independently for each model. The VLISM energy spectra generated by the models agree reasonably well with the observed VLISM energy spectra for the elements with Z = 1–28 and with the isotopes with Z = 1–14. However, to achieve reasonable fits to the 2 H and B energy spectra, it was necessary to add a primary source of 2 H and B.

HighlightsWhat are the main findings?Two custom devices were successfully designed and prototyped: a wearable wristband, and a configurable BLE beacon with adjustment of transmission parameters.The laboratory tests confirm stable operation of devices, showing improved RSSI consistency and extended autonomy under different configurations.What is the implication of the main finding?The development validates the feasibility of tailoring BLE-based devices to overcome the limitations of commercial alternatives, enabling greater control over energy efficiency and signal stability.These advances highlight the potential of the proposed hardware for further refinement and adaptation to real-world experimental setups.This work presents the design and prototyping of two reconfigurable BLE-based devices developed to overcome the limitations of commercial platforms in terms of configurability, data transparency, and energy efficiency. The first is a wearable smart wristband integrating inertial and biometric sensors, while the second is a configurable beacon (ASIA Beacon) able to dynamically adjust key transmission parameters such as channel selection and power level. Both devices were engineered with energy-aware components, OTA update support, and flexible 3D-printed enclosures optimized for residential environments. The firmware, developed under Zephyr RTOS, exposes data through standardized interfaces (GATT, MQTT), facilitating their integration into IoT architectures and research-oriented testbeds. Initial experiments carried out in an anechoic chamber demonstrated improved RSSI stability, extended autonomy (up to 4 months for beacons and 3 weeks for the wristband), and reliable real-time data exchange. These results highlight the feasibility and potential of the proposed devices for future deployment in ambient assisted living environments, while the focus of this work remains on the hardware and software development process and its validation.

The development in the field of technology has led to an increased need to develop optical fibers due to their ability to transmit information and data with the least amount of attenuation over long distances between city centers. In this research, mode properties calculation for five step-index single-mode optical fibers with core radii of (1.9 - 2.9) μm where the increase in radius is 0.25μm, with core and cladding indices (n1=1.4652, n2=1.458496157), respectively and a numerical aperture of 0.14 has been done at 1064 nm wavelength using RP Fiber Calculator (free version 2025). The fundamental fiber mode properties such as effective area, power propagated in the core, propagation constant and effective refractive index were calculated. Intensity distributions for the mode were shown. It was noted that the effect of increasing the core radius led to an increase in the core power and it was also observed that the propagation constant and effective refractive index increase with the increase in the radius of the core. It was obtaining percentage power more than 50%. Results of this work will be useful in the design of optical fibers. Results from the calculator were compared with those calculated from equations and with previous study and it was concluded that all calculated properties are in good agreement

The proliferation of wireless networking solutions, which are omnipresent in our daily lives, has led to increased exposure to the energy of electromagnetic (EM) waves in the higher frequency range, raising concerns about their impact on human health. Investigating the propagation of EM waves through multilayer structures can shed light on the future direction of effective protection and shielding solutions. The paper provides a comparative study that examines EM wave propagation through a multilayered composite structure. The structure combines Plexiglas plates (acrylic, polymethyl methacrylate), a dielectric material, with one or more layers of conductive YSHIELD HSF54 paint to reduce EM field intensity. The paint’s carbon-based particle composition promises effective field attenuation. Our side-by-side comparative real-world measurements and simulation results showcase correlation. We further demonstrated the benefits of applying a layer of conductive YSHIELD HSF54 paint over Plexiglass to form a composite structure, with the initial layer contributing to attenuation of approximately 20 dB. Finally, the results were validated by calculating Morozov’s first- and second-order analytical approximations for the transmission parameter S21—the calculated values accurately trace both the simulations and measurements. The research concludes that shielding, which is used as a method of protection against EM radiation in many industrial devices, can also be used in procedures to protect human habitats by selecting new, innovative, and affordable materials and structures.

Abstract We demonstrate that $\mathcal{PT}$-symmetric mixed linear-nonlinear lattices can sustain mixed-gap vector solitons in the coupled nonlinear Schrödinger equations with fractional diffraction. Here, mixed-gap vector solitons refer to solitons whose first and second components exist in different band gaps. In this work, the first component is a fundamental soliton, while the second is a dipole. When the propagation constant of the first component is fixed, the soliton power of the first component decreases as the propagation constant of the second component increases. Conversely, the power of the second component increases with its own propagation constant. We study cases with both large and small values of the Lévy index. We also study the stability of these solitons, using linear stability analysis and perturbed propagations. Interestingly, the stability domains of vector solitons with a large Lévy index are consistently much wider than those with a small Lévy index.

Abstract Improving the efficiency of electron acceleration in a vacuum presents a significant challenge in sophisticated laser-driven acceleration methodologies. This research examines the combined effects of Hermite-Sinh-Gaussian (HShG) laser beams (laser electric field amplitude, Hermite polynomial mode index, Decentered parameter of Sinh function) and magnetic wigglers (wiggler magnetic field amplitude, wiggler field propagation constant) on electron dynamics to facilitate high-energy acceleration. The distinct intensity and phase distribution of HShG beams alter the trajectory of electrons, facilitating effective energy transfer. The periodic magnetic field of the wiggler enhances resonance conditions, thereby sustaining prolonged interactions between electrons and the laser field. The numerical analysis indicates that the integration of these two mechanisms markedly enhances the relativistic factor ( γ ) of electrons, resulting in greater energy gains. The findings demonstrate that customized laser beam configurations and external magnetic fields can enhance laser-driven acceleration in vacuum, presenting a viable strategy for future compact accelerators. This study offers insights into optimizing acceleration efficiency for high-energy physics applications, free-electron lasers, and advanced radiation sources.

The use of the method of Muller boundary integral equations for solving the problem of eigenwaves of weakly guiding dielectric waveguides was justified. A theorem was proved about the spectral equivalence between the original differential problem and the problem for the system of Muller boundary integral equations on the physical sheet of the Riemann surface, where the eigenvalues, the propagation constants of the eigenwaves, are sought. With this aim, the localization regions of the spectra of the original problem and a so-called “turned inside out” problem generating spurious eigenvalues were analyzed. A sufficient condition of equivalence was obtained: the problems are equivalent if the problem turned inside out has only a trivial solution. Consequently, as confirmed by the results of the numerical experiments, only true eigenvalues on the physical sheet of the Riemann surface can be found by using the method of Muller boundary integral equations.

Abstract Using polymer microwave fibers as waveguides has attracted significant attention over the last years. They are an attractive replacement for optical fibers or copper wires due to their price, flexibility, and robustness against electromagnetic interference. This work investigates the behavior of the wave propagation of a circular-shaped polymer microwave fiber mathematically and provides wide-band measurement results. The mathematical model is completely analytical and does not need any 3D finite element method simulation. After a short theoretical introduction, we compare the theoretical results with measurements performed by a vector network analyzer from 20 GHz up to 150 GHz. The behavior of the propagation constant, propagation speed, and group delay are compared with the predicted results. The maximum relative error between the theoretical prediction and the measurements was less than 0.7%.

Objectives. The study sets out to develop and analyze a mathematical model for information transmission in multimode fiber-optic ring networks using a token-based access method to ensure efficient interaction between Internet of Things (IoT) devices. The work aims to evaluate the probabilistic and time-related characteristics, as well as the reliability and performance of the network infrastructure to optimize data transmission parameters, taking into account the specifics of IoT and the peculiarities of the fiber-optic medium.Methods. Reliability theory methods are used to assess the network’s resilience to failures and increase its operational efficiency, along with techniques from the theory of stochastic processes to model the dynamics of data transmission under varying loads and approaches from queueing theory to analyze traffic distribution and packet queue management. The Laplace–Stieltjes transform is applied to derive functional equations that describe the probabilistic and time-related data transmission characteristics, enabling precise mathematical modeling of network processes.Results. The information transmission processes occurring in multimode fiber-optic networks with token access in the context of IoT systems were studied. The temporal characteristics of packet transmission for different classes, including critical IoT device data, were analyzed.Conclusions. The results confirm that multimode fiber-optic media provide an efficient foundation for IoT infrastructure that offers both high throughput and fault tolerance. By incorporating reliability characteristics into the model, it was possible to account for the impact of fiber-optic medium and network node failures on performance. Optimizing the parameters of the token-based access method, including time intervals and token transmission policies, significantly improves overall network performance by reducing collision probability and increasing throughput. The developed mathematical model provides an effective tool for analyzing and designing local networks based on multimode fiberoptic technologies. This fact is especially important for networks serving critical infrastructure.

Doping effects of the p-semiconductors on the electromechanical coupling coefficient of Rayleigh waves propagation in a PSC layered structure

Frequency efficiency and noise immunity are the most important parameters of binary message transmission. The immunity of binary message transmission to pulse interference can be increased by organizing simultaneous (parallel) transmission of message elements by orthogonal signal functions. The article analyzes the transmission of binary messages directly by signal functions obtained by orthogonalization of overlapping narrowband signals and transmission by signal functions formed using the Hadamard matrix. The formation of the transmitted signal and processing of the received signal are considered. The immunity of transmission to pulse interference is estimated using modeling. Transmission using the Hadamard matrix has better noise immunity to pulse interference. This is due to a more uniform distribution of the envelopes of signal functions in time.

Sound-absorbing materials in the frequency range can be characterised upon the basis of their propagation constant and characteristic impedance. For a number of years, there have been empirical models, such as that of Delany and Bazley, which adjust these parameters to the flow resistivity and frequency, defining fitting coefficients. Based on the Delany–Bazley model, further adjustments of these coefficients have been proposed to improve the prediction of specific materials. The most commonly used adjustments are based on a quadratic error function for the normal incidence sound absorption coefficient or the surface impedance. Three adjustment methods are displayed in this paper to obtain new open-pore foam coefficients. The propagation constant and characteristic impedance measurements are adjusted, with different error functions and minimisation algorithms. New and improved models are obtained upon the basis of these three methods. The results obtained display satisfactory adjustments of all the material variables.

Low energy efficiency, misalignment-induced energy loss, limited range, and sensitivity to external variables describe Wireless Power Transfer (WPT) solutions for Internet of Things (IoT) devices. Traditional methods include inductive and RF-based WPT with uneven power distribution in dynamic environments and proximity restrictions. The proposed system dynamically changes transmission parameters and combines adaptive resonance tuning and beamforming to improve energy economy, range, and stability using machine learning (ML) for real-time adaptation. Simulation and experimental results reveal considerable increases in power transmission efficiency with the proposed system obtaining up to 95% efficiency at 1 meter compared to 82% and 88% in the existing systems. Energy loss at 1 meter is 0.15 W; at 7 meters, stability gains from just an 8% fluctuation in power output. The results provide a feasible substitute for sustainable wireless power transfer and prove the brilliance of the proposed system in long-range and dynamic IoT applications.

Wireless communication technologies play a key role in providing efficient and reliable Internet of Things (IoT) networks. Among them, Long Range (LoRa) technology and the LoRaWAN protocol are widely known for their ability to provide long-range communications with low power consumption and cost-effectiveness. One of the main challenging issues in deploying autonomous wireless networks is the ongoing need to optimize transmission parameters to minimize node energy consumption (EC) and maximize packet delivery ratio (PDR). This study introduces a novel transmission parameter selection algorithm such as Spreading Factor (SF) and Transmission Power (TP), leveraging machine learning (ML) methods such as XGBoost, GRU, and RBFN. The algorithm predicts the distance to a node based on the received RSSI, and subsequently forecasts EC and PDR, substantially enhancing network performance. The proposed approach demonstrates high prediction accuracy, achieving 99%, while reducing EC by 20.43% and increasing the PDR by 23.72% compared to the traditional adaptive data rate (ADR) algorithm

This study presents a comprehensive analysis of LoRaWAN-based IoT communication in an agricultural monitoring context. The research is grounded in long-term experimental data collected from four environmental sensors deployed in the Czech Republic, focusing on temperature and humidity measurements. Beyond the environmental data, the study emphasizes the technical performance of the deployed devices, particularly in terms of signal quality and energy efficiency. We analyzed 14 key transmission parameters, including RSSI, SNR, Time on Air, and gateway reception metrics, to evaluate the communication reliability and network coverage. A significant contribution of this work is the development of a data-driven model for estimating battery life based on real-world usage patterns and spreading factor distributions. This model enables predictive maintenance planning and supports energy-efficient network design. The study builds on previous research and contributes to the growing body of literature on holistic performance evaluation in IoT systems.

Decorative construction typically accounts for 20–50% of total project costs. China introduces energy-saving panels, primarily composed of sand particles, to reduce its energy consumption. Most importantly, it has the ability to efficiently resolve intricate acoustic issues with remarkable speed and convenience. This study focuses on sand-based energy-saving panels, which efficiently address complex acoustic issues while reducing energy consumption. Using Delany-Bazley empirical models and acoustic simulation software (Zorba, INSUL), four surface treatments (Plain-P, SA1, PF, SA2) were compared to optimize room acoustics. Results show that plain sand spray (Plain-P) exhibits the highest sound absorption capacity, with a noise reduction coefficient (NRC) of 0.85 and a sound absorption coefficient exceeding 0.9 in high frequencies. Simulation of rooms with sand-based wall coatings confirms its environmental friendliness and adaptability to curved surfaces, arched ceilings, and special-shaped walls. The results demonstrate that empirical models and simulation together improve the approach to studying acoustic parameters like sound absorption through sound impedance and propagation coefficient. Additionally, the material expresses excellent sound insulation, with an average transmission loss (TL) of approximately 70.71 dB. This research highlights the overlooked potential of sand-based materials, providing a practical solution for energy-efficient and acoustically optimized interior design, specifically emphasising a method that has not been paid much attention to.

Global transmission characteristics of mpox outbreaks: a systematic review and meta-analysis