bluuebunny/crossref_metadata_2025 huggingface dataset:
Dynamic and nonequilibrium amplification of the proximity effect in superconductors
Authors: Seminozhenko V. P. , Khar’kov E. I. , Shafranyuk S. E.
Published: December 2024

The effect of a high-frequency alternating voltage applied to the plates of a tunnel N/S sandwich (S is the superconductor, N is the normal metal or superconductor having the smaller gap) is examined. It is shown that for ΔN ≪T ≪ Δs(ΔN, ΔS, are the energy gaps in the electronic spectra of N and S films, respectively, and T is the temperature of the sandwich) the nonequilibrium effect of amplification of superconductivity in the N film can in many cases be comparable to and even exceed, the usual proximity effect. The corrections to the quantity ΔN, related to the effect of the alternating voltage on the virtual tunneling transitions of electrons, are found.
Possible plasticity mechanism in pure quantum crystals
Authors: Strzhemechnyi M. A.
Published: December 2024

A kink on a dislocation is shown to have a band nature. Such quasiparticles have their maximum mobility in quantum crystals. The quantum nature of a kink of this kind manifests itself, in particular, in the fact that its average velocity decreases with increasing stress at sufficiently low temperatures and high stresses (not exceeding the Peierls stresses). The parameters characterizing the plasticity of real hydrogen crystals are estimated. A new pinning mechanism is suggested in which the dislocation is stopped by a pair of nearest-neighbor-ortho-molecules.
Localization of vortex formation in a superfluid liquid and an analog of Zhukovskĭ’s hypothesis
Authors: Kiknadze L V. , Mamaladze Yu. G.
Published: December 2024

It is shown that the presence of a vortex near a sharp protrusion compensates the infinite velocity of potential flow over the tip. This circumstance is discussed from the point of view of localization of vortex formations in the superfluid liquid.
Electrical resistivity of yttrium single crystals in the range 4.2−300 K
Authors: Volkenshteĭn N. V. , Dyakina V. P. , Kumin P. R. , Startsev V. E. , Volkov V. T. , Nikiforova T. V.
Published: December 2024

The electrical resistivity of pure yttrium single crystals (ρ273.2/ρ4.2≃700) oriented along the ⟨0001⟩ and ⟨101¯0⟩ axes has been investigated in the temperature range 4.2−300 K. It was established that the scattering of electrons by phonons is described by the Bloch–Grüneisen function for both orientations over the whole temperature range, with the parameter ΘR equal to the Debye temperature ΘD. It was found that a contribution to ρ(T) quadratic in the temperature is two orders of magnitude greater than in other transition metals. It is shown that the anisotropy in the electrical resistivity of yttrium at T∼ΘD is completely determined by the anisotropy of its Fermi surface.
Quasi-two-dimensional Wigner crystals with a compound lattice
Authors: Vil’k Yu. M. , Monarkha Yu. P.
Published: December 2024

We demonstrate that it is possible to create a two-dimensional Wigner crystal with a compound lattice in a He3−He4 solution with microlayering or on a superfluid helium film covering a very smooth solid substrate. We show that a compound lattice is formed through the interaction of two planar Wigner lattices of the same charge located one above the other and separated by a finite distance. A theoretical analysis of the stability of such crystals shows that various structural transitions must occur in the system when the distance between the layers is changed.
Thermal-electric domains in normal metals
Authors: Boiko V. V. , Podrezov Yu. F. , Klimova N. P.
Published: December 2024

The authors have experimentally investigated the current-voltage characteristics of copper and platinum wire specimens (R300/R4.2≃102), cooled by saturated helium vapor at about 4.2 K. They have analyzed the features of the I–V characteristics that are associated with the formation of thermal-electric domains. The values determined for the maximum temperature, shape, and size of the domains are compared with those calculated from the solution of the heat equation with allowance for real conditions of heat transfer and mechanisms of energy dissipation in the bulk metal.
Processes of the second order with respect to the electron–phonon interaction in point contacts of normal metals
Authors: Kulik I. O. , Omel’yanchuk A. N. , Tuluzov I. G.
Published: December 2024

The authors have derived, to within terms of the second order in d/lε∞ [d is the contact diameter, lε∞=vF/λωD is the inelastic electron mean free path, and λ is the electron-phonon interaction (EPI) constant], an expression for the second derivative of the I–V characteristic, gpc(1)(eV)+ const1∫​0eVgpc(2)(ω)(dω)/(ω)+ const2∫​0eVfpc(ω,eV−ω)dω, where gpc(1)(ω)≡gpc(ω)=α^2(ω)F(ω) is the first-order EPI function of the contact, and gpc(2)(ω) and fpc(ω1,ω2) are second-order EPI functions of the contact. The second term represents an energy-dependent “background” that appears in point-contact spectra because of reabsorption and drag of nonequilibrium phonons, and the third term describes two-phonon processes. The function gpc(2)(ω) is distinguished from gpc(1)(ω) by (in addition to the K factor) the presence of the phonon group velocity wz=δω˙q/δqz in the denominator of the integrand and, therefore, is a more singular function of ω than is qpc(1)(ω), and contains additional information about the electron–phonon interaction of the metal.
Theory of the phase diagram of a uniaxial magnet in a transverse magnetic field
Authors: Borisenko V. G. , Pereverzev Yu. V.
Published: December 2024

The following results are obtained for a uniaxial ferromagnet with a single-ion anisotropy of the easy-axis type with an arbitrary ratio of the anisotropy and exchange. For spin S = 1, an equation which describes the magnetic states of the ferromagnet in the H−T plane in the presence of an arbitrary magnetic field is obtained in the random-phase approximation. For the case of a transverse magnetic field and arbitrary spin S, the equation of the phase curve in the H−T plane is obtained in the molecular-field approximation. The phase diagrams for the compounds NiSiF6 · 6H2O and NiZrF6 · 6H2O are constructed and the results are compared with experimental data.
Coherent interaction of light with atomic dipole moments in single-crystalline gadolinium
Authors: Beznosov A. B. , Gnezdilov V. P. , Eremenko V. V.
Published: December 2024

The interaction of light with systems of almost free quasibound electrons in single-crystalline gadolinium in the region of d–f exchange resonance (0.49 ≤ ℏω ≤ 1.1 eV; 4.2 ≤ T ≤ 343 K) is studied experimentally and theoretically. It is found that the position of the resonant optical-absorption bands is determined by the d–f exchange interaction within a single atom, and their intensity is determined by the orientation and degree of ordering of the intra-atomic optical dipoles.
Surface scattering of electrons and the nature of ballistic excitation in zinc
Authors: Mishin V. A. , Tsymbal L. T. , Cherkasov A. N.
Published: December 2024

Experiments were performed to investigate the Gantmakher–Kaner effect in zinc due to electrons near the reference point of the lens. The complicated (two minima) amplitude-angular dependence of the effect was found to change into a monotonic function as the surface state of the sample is altered. This change was established to be due to a transition from mainly specular to diffuse surface scattering of the electrons.
Contractile responses of engineered human μmyometrium to prostaglandins and inflammatory cytokines
Authors: Maxey Antonina P. , Wheeler Sage J. , Travis Jaya M. , McCain Megan L.
Published: December 2024

Preterm labor is a prevalent public health problem and occurs when the myometrium, the smooth muscle layer of the uterus, begins contracting before the fetus reaches full term. Abnormal contractions of the myometrium also underlie painful menstrual cramps, known as dysmenorrhea. Both disorders have been associated with increased production of prostaglandins and cytokines, yet the functional impacts of inflammatory mediators on the contractility of human myometrium have not been fully established, in part due to a lack of effective model systems. To address this, we engineered human myometrial microtissues (μmyometrium) on compliant hydrogels designed for traction force microscopy. We then measured μmyometrium contractility in response to a panel of compounds with known contractile effects and inflammatory mediators. We observed that prostaglandin F2α, interleukin 6, and interleukin 8 induced contraction, while prostaglandin E1 and prostaglandin E2 induced relaxation. Our data suggest that inflammation may be a key factor modulating uterine contractility in conditions including, but not limited to, preterm labor or dysmenorrhea. More broadly, our μmyometrium model can be used to systematically identify the functional impact of many small molecules on human myometrium.
Combined effect of confinement and dielectric exclusion on ion adsorption in slits, pores, and cavities
Authors: Szarvas János , Valiskó Mónika , Gillespie Dirk , Boda Dezső
Published: December 2024

We present simulation results for the Donnan equilibrium between a homogeneous bulk reservoir and inhomogeneous confining geometries with varying number of restricted dimensions, dc. Planar slits (dc = 1), cylindrical pores (dc = 2), and spherical cavities (dc = 3) are considered. The walls have a negative surface charge density. Because different dielectric constants are used in the reservoir and confined system, we used the Donnan grand canonical Monte Carlo method [Boda and Gillespie, J. Mol. Liq. 391, 123372 (2023)] to simulate the equilibrium. The systems with larger confining dimensionality produce greater adsorption of counterions (cations) into the confinements, so cation selectivity increases with increasing dimensionality. The systems with smaller dielectric constants produce more effective coion (anion) exclusion, so cation selectivity increases with decreasing dielectric constant. The combined effect of a more confining space and solvation penalty produces even more efficient anion exclusion and cation selectivity than each separately.
Hermite–Gaussian solitons in 1+2 dimensional nonlocal nonlinear systems with Y0-oscillatory response
Authors: Wang Jing , Li Xiyue , Zhang Peishan , Hu Wei
Published: December 2024

We investigate the Hermite–Gaussian solitons in 1+2 dimensional nonlocal nonlinear systems with Y0-oscillatory response. The iterative solution of the solitons is numerically found using the accelerated imaginary-time evolution method with amplitude normalization. The existence interval of the solitons is determined based on the boundary conditions, the degree of nonlocality, and the normalized amplitude. The stability of the solitons is demonstrated through a series of numerical simulations. The soliton exhibits breathing behavior during propagation when the incident intensity is increased. The propagation characteristics of higher order Hermite–Gaussian solitons are also investigated.
Improved high-precision regional marine geomagnetic anomaly field model using Legendre polynomial expansion
Authors: Zhu Bo , Li Houpu , Zhu Libo , Chen Cheng , Wu Shuguang
Published: December 2024

Regional geomagnetic field models can provide detailed insights into the geomagnetic field and are of substantial value for precise maritime navigation and the detection of marine targets. In light of the polynomial model’s numerous advantages, including straightforward computation, rapid computation speed, and high model resolution, this study delves into the polynomial modeling method. To address the challenges of enhancing solution precision, selecting the optimal polynomial function, and determining the optimal truncation degree, it introduces an improved method based on singular value decomposition to enhance the model’s accuracy at higher degrees. A comparison of the Taylor polynomial model, the Laguerre polynomial model, and the Chebyshev polynomial model revealed the superiority of the Legendre polynomial model in terms of truncation degree, modeling accuracy, and boundary effect. In addition, by employing K-fold cross-validation, the complete dataset is effectively leveraged for both fitting and validation, thereby facilitating the identification of the optimal truncation degree for each polynomial model. The superior accuracy of the regional geomagnetic field models is validated through a comparative analysis of the calculation results derived from the EMM2017 model.
Evaluating the outcomes of Australia’s first all-age public hospital Sport and Exercise Medicine Outpatient Clinic: a retrospective cross-sectional study
Authors: Middleton Dougal , Thompson Fintan , James Kira
Published: December 2024

Objectives This study aimed to evaluate the outcomes of Australia’s first public hospital all-age Sport and Exercise Medicine Outpatient Clinic (SEMOC). Methods A retrospective cross-sectional study of patients referred to and reviewed in the SEMOC, during a study period from March to October 2023, was performed. Outcomes were the number of appointments, number of patients reviewed, proportion reviewed within Queensland Health recommended timeframes, patient satisfaction, proportion of Aboriginal and Torres Strait Islander patients, and the rurality of the patients based on the Modified Monash Model of remoteness. Results There were 29 clinics, 472 allocated appointments, and 270 new patients referred to the SEMOC (1.7 appointments per patient). Almost a quarter (23.7%) of patients identified as Aboriginal and Torres Strait Islander peoples and a third (31.9%) were from rural or remote regions. Most (88.7%) patients referred during the study period were seen within the Queensland Health recommended timeframes, and almost all patients referred on for orthopaedic review were booked for surgery (93.6%). Over 90% of patients were satisfied with the quality of treatment they received and rated the overall service as good to excellent. Conclusion A SEMOC public hospital model has been shown to be feasible for providing care to patients with musculoskeletal conditions, reaching patients who face barriers to health care, reducing wait times, and improving referral for surgery. The model may assist in meeting Australia’s growing demand for orthopaedic and musculoskeletal medicine and expand within Australia’s public hospital system to become a nationally accepted practice.
Key comparison BIPM.RI(I)-K5 of the air-kerma standards of the GUM, Poland and the BIPM in 137Cs gamma radiation
Authors: Kessler C , Roger P , Derlaciński M , Szymko M
Published: December 2024

Main text

A new indirect comparison of the standards for air kerma of the Główny Urząd Miar (GUM), Poland, and of the Bureau International des Poids et Mesures (BIPM) was carried out in the 137Cs radiation beam using the radiation protection facility of the International Atomic Energy Agency (IAEA) in Seibersdorf, Austria, in June 2024. The comparison result, based on the calibration coefficients for two transfer chambers and expressed as a ratio of the GUM and the BIPM standards for air kerma, is 1.0005 with a combined standard uncertainty of 2.8 parts in 103. The results are analysed and presented in terms of degrees of equivalence, suitable for entry in the BIPM key comparison database, to update the 2006 comparison result.

To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.

The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).
Quantitative Measurement of Temperature-Dependent Quasiparticle Scattering of the Topological Surface States in Bi2Se3
Authors: Lu Shengyue , Zhang Yeqinbo , Ma Xueyan , Li Jingze , Deng Yongkai , Liu Yunquan
Published: December 2024

The quasiparticle scattering processes of the topological surface state (TSS) in three-dimensional topological insulators (TIs) have a vital effect on the many-body interactions and potential applications of topological materials. In this study, we performed high-resolution temperature-dependent angle-resolved photoemission spectroscopy analysis of the 3D strong TI Bi2Se3. Using an ab initio simulation, we analyzed the temperature dependence of the electronic structure and lifetime broadening of the TSS, which are closely associated with the quasiparticle scattering process, i.e., electron–phonon coupling and spin-dependent scattering. We show that, at a low temperature (7 K), the spin-dependent electron scattering facilitates the anisotropic scattering rate of the TSS. Conversely, at room temperature (300 K), the electron–phonon coupling dominates the contribution to the scattering rate. The scattering rate increases with temperature and becomes uniform in momentum space owing to the temperature dependence of quasiparticle scattering. The quantitative study of temperature-dependent scattering rates in TSS is crucial to understanding the topological property and transport mobility of Dirac fermions for fundamental studies and potential applications.
A Linear Programming Approach to Ensuring Equitable Distribution of COVID-19 Vaccines in Lower Income Countries
Authors: Gupta Sandhya , Srivastava R.K.
Published: December 2024

The equitable dissemination of COVID-19 vaccinations in lower-income nations presents a crucial worldwide dilemma, necessitating smart allocation techniques to guarantee impartial and effective coverage. This paper introduces a mathematical approach that utilizes Linear Programming (LP) to efficiently distribute vaccination doses among lower-income countries. The model incorporates crucial variables such population magnitude, healthcare infrastructure capability, susceptibility to the virus, financial limitations, and worldwide vaccine availability. The linear programming (LP) model is constructed using decision variables that indicate the quantity of vaccination doses assigned to each country. The goal function seeks to optimize the fair allocation of resources by giving weights to countries according to certain criteria. Constraints are imposed to ensure compliance with global vaccine supply, population coverage targets, healthcare capacity, vulnerability concerns, and budget limits. The non-negativity constraints guarantee that the vaccination allocations will always be greater than or equal to zero. The model is designed to be flexible, taking into account dynamic factors such as emerging viral strains and fluctuating vaccination availability. It highlights the significance of timely data updates to facilitate decision-making. The LP solver, such as the simplex method or interior-point approaches, is used to determine the best solution that achieves a fair distribution while considering logistical limitations. The results obtained from the linear programming (LP) model offer practical and effective guidance for policymakers and health organizations. These insights help in distributing COVID-19 vaccinations in a way that maximizes their impact and reduces inequalities among lower-income countries. The approach recognizes the interdependence of global health and emphasizes the need for coordinated endeavors in addressing the pandemic. This mathematical model is a useful tool in the ongoing efforts to distribute COVID-19 vaccinations fairly and efficiently. It contributes to the worldwide aim of obtaining universal immunity and overcoming the problems posed by the epidemic in lower-icnome countries.
Ramification of Nd3+ substitution on Structural, Optical, and Dielectric Properties of LaPO4 Ceramics
Authors: Khanna Kanchan , Kumar Akshay , Ram Tiku , Dwivedi Sunil , Kumar Sunil
Published: December 2024

Phosphors
x
Nd3+
1-

x
La3+PO4 where x = 0.02, 0.04 and 0.06 have been reliably synthesized utilizing Auto Combustion method. Structural phase formation has been verified using X-ray diffraction, while scanning electron microscopy was used for morphological and elemental investigation. Luminescence behavior has been studied from PL spectra whereas CIE coordinates give information about luminescence shift. The dielectric behavior of prepared phosphor has been investigated using impedance analysis.
Synthesis and Characterization of Mixed Phase Manganese Oxide Nanoparticles Prepared by Simple Co-Precipitation Method
Authors: Kapil Ishita , Yadav Chandrakala , Yadav Pinky , Bhaduri Ayana
Published: December 2024

With their exceptional qualities such as greater specific surface area, a greater surface atoms fraction, non-toxicity, and outstanding redox properties, manganese oxide nanoparticles-a transition metal oxide with a variety of crystal phases, morphologies, and structural diversity-are attracting attention for use in several storage science applications, particularly in batteries, supercapacitors, energy conversion, environmental catalysis, and wastewater treatment. Particle size, morphology, surface area, and Mnx
+ oxidation state are just a few of the variables that must be precisely controlled to fully realize their application potential. The present study outlines the synthesis of manganese oxide nanoparticles through a facile co-precipitation process that employs double precursor salts of manganese, namely manganese sulphate and potassium permanganate, along with three surfactants: Cationic-Potassium chloride (KCl), Non-ionic - Polyethylene glycol (PEG), and Anionic- sodium dodecyl sulphate (SDS), respectively. At 500°C, the samples are subsequently annealed. Samples are examined using XRD, both as prepared and annealed. In the absence of any calcination treatment, the MnO2 -precursor was primarily an amorphous phase with indistinct amorphous α-MnO2 crystal patterns for all the samples. Well-defined crystalline prominent peaks of α-Mn2O3 with some traces of α-MnO2 visible for samples prepared with different surfactants and without surfactants after calcination at 500°C. Crystallite sizes and macrostrains etc are estimated. By using this one-pot calcination method, mixed phases of α-MnO2 and α-Mn2O3 were produced. The thermogravimetric analysis also supports the results.
Effect of zinc oxide dopant on the structural, optical, and magnetic properties of α-Fe2O3 nanocrystalline structure
Authors: Seema S , Bhatt Praveen , Meenakshi  , Sharma Rajesh
Published: December 2024

Recent research demonstrates that unique progressive properties of nanomaterials have contributed to significant advancements in several fields. Therefore, in the current study zinc oxide (5%, 10%, and 20%) - doped Fe2O3 nanoparticles were synthesized by an advanced co-precipitation method. Further, the prepared samples were calcined for two hours at a temperature of 600°C and the samples were characterized using various techniques to check their suitability in various applications. For that purpose, initially the formation of nanoparticles was confirmed using X-Ray diffraction analysis (XRD) data that concluded the formation of hexagonal crystalline structure. The crystallite size was also calculated using Debye Scherrer formula and size of particle increased from 23nm to 30nm with increase in dopant concentration. The IR spectroscopy were used to analysed the various calcined samples and the results show that the sharp peaks at position 540 cm−1 and 625 cm−1 were due to O-Fe-O vibration alpha and gamma Fe2O3 molecules respectively. The UV -Vis spectroscopy were used to determine the optical band gap of calcined samples through Tauc Plots and the results of study reflected that small decrement of band occurred with increase of dopant concentration. The magnetic properties of the calcined sample were analysed by Vibrating sample magnetometer (VSM) and it was observed that the saturation magnetisation intensity decreases as doping concentration of zinc oxide increases.
Thermal analysis of chemically reactive MHD flow through rotating horizontal channel in the existence of Hall current and radiation
Authors: Saboo Ruchi , Sharma Pooja , Chaudhary Ravi , Sharma Tarun
Published: December 2024

The current work aims to analyze the chemically reactive, MHD convective flow through the horizontal porous (Darcy’s model) channel, which rotates in its plane due to radiation and hall current existence. The flow prototype is designed, and equations are formed and the closed-form results are achieved. In addition, non-dimensional quantities (such as; shear stress, Nusselt and Sherwood numbers) are explored for concerned flow constraints. It is perceived that velocity detracts in the x and y direction with the rise in the parameter of rotation, and the temperature field decreases with the growth in radiation, heat source and Prandtl number. The concentration profile abruptly increases due to the growth in a chemical reaction. This work finds notable applications in the engineering domain.
Complement of Equal-Square Graph of Finite Groups
Authors: Kumar Narinder
Published: December 2024

The Complement of Equal-Square graph of a finite group G denoted as CES(G) is a finite, simple and undirected graph having pair of different vertices x
1 and x
2 have edge iff

x
1

2

≠

x
2

2

. This research gives graphical representation of the Complement of Equal-Square graph of the cyclic and dihedral groups is done. Structural properties such as clique number, degree of a vertex, independent number, connectedness, girth, chromatic number, and matching number of Complement of Equal-Square graph of the cyclic and dihedral group are studied.
Prediction of induced soil vibration during pile vibrodriving using Dynamic Mode Decomposition (DMD)
Authors: Williams-Riquer Francisco , Chmelnizkij Alexander , Alkateeb Diaa , Grabe Jürgen
Published: December 2024

This study investigates using the Dynamic Mode Decomposition (DMD) algorithm to perform approximations and time-ahead prediction of soil vibrations during the vibrodriving process. Geotechnical applications face challenges in modeling and predicting soil vibrations due to the soil’s heterogeneous nature. This study addresses this issue using a purely data-driven approach. Geophone data collected during pile installation using a vibrodriver were used to demonstrate the feasibility of the DMD algorithm. The research reveals that both the standard DMD and augmented DMD, which incorporate delay coordinates, can achieve accurate predictions, with the augmented DMD producing more accurate time-ahead predictions of the vibrations. The results emphasize the potential practical utility of data-driven methods for vibration prediction in geotechnical applications.
Designing a vibration energy harvester for several directions of excitation in planar motion
Authors: Shabanalinezhad Hossein , Malcovati Piero , Svelto Cesare , Gatti Gianluca
Published: December 2024

Harvesting energy from a mechanical vibration source is always challenging and comes with drawbacks, especially when the vibration input changes direction very often. This research proposes a novel design to harvest energy from a planar mechanical vibration source no matter its direction of oscillation. To achieve this, a spiral beam with a tip mass is designed to be flexible to various directions of the vibration input in a horizontal plane, which is orthogonal to the direction of gravity. An approximate analytical investigation is first performed. Numerical simulations are then conducted using commercial FEA software and the results are in good agreement with the analytical approach. Numerical simulations show that the tip mass acts symmetrically in the plane, although the system is not geometrically symmetric. To experimentally validate the proposed configuration, a 3D-printed prototype device was manufactured and attached to a shaker, which induced a vibrating motion for the tests. A piezoelectric patch was attached to the curved beam to generate electrical energy and measurements of produced open-circuit voltages were taken for different directions of the exciting vibration.
Computation of the Damping Loss Factor of Heterogeneous Meta-structure using the Wave Finite Element-based Methodology
Authors: Cui Dongze , Ichchou Mohamed , Atalla Noureddine , Zine Abdel-Malek
Published: December 2024

Existing methodologies employed for the computation of vibroacoustic indicators of heterogeneous structures with high contrasting properties have limitations in terms of precision and computational speed. The present study, focuses on estimating the composite Damping Loss Factor (DLF) of these structures. It presents a Wave Finite Element-based methodology that uses the forced response of a Unit Cell (UC) representative of the periodic meta-structure to calculate the DLF through a power balance. Various configurations, ranging from a simple plate to complex laminated configurations, are presented to highlight the advantages and limitations of the presented methodology.
On the Significance of Parameter Uncertainties for Prediction of Leak Noise Wave Speed in Buried Pipes
Authors: Scussel O. , Muggleton J M , Karimi M , Williams P , Kalkowski M K , Joseph P F , White P.
Published: December 2024

The modern world is facing the challenging issue of water wastage due to leaks, which is causing severe economic, environmental and social impacts. Consequently, the inspection and maintenance of buried water pipes is crucial and there is still a lack of investigations towards the uncertain parameters affecting the wave speed associated with the predominantly fluid-borne wave s=1, the main carrier of leak noise. This study investigates the effects of uncertainties present in the pipe and soil parameters which are affecting the speed of propagation of the leak noise wave. To achieve this, a sensitivity analysis is performed using Monte Carlo simulations and Sobol’ indices. Uncertainties are commonly associated with the material and geometrical properties of the pipe along with the surrounding soil characteristics. However, the significance of these parameters varies depending on the type of soil in which the water pipe is buried. In clay soil, the soil-related parameter plays a crucial role compared to sandy soil and this is verified through some experimental work carried out in two water pipe systems with very different properties, one in the UK and the other one in Brazil. This research is of fundamental importance for determining the most critical parameters affecting the leak noise wave, allowing to evaluate and integrate uncertainty information into decision-making of current technologies, such as loggers and leak noise correlators, aiming enhanced detection and location of water leakage in buried plastic water pipes.
Estimation of loosening torque in bolted joints from experimental data and regression models
Authors: Coelho Jefferson , Machado Marcela , Dutkiewicz Maciej
Published: December 2024

Structures are often joined using fasteners such as rivets or bolts, which are chosen based on their ability to meet performance requirements. Bolts are popular due to their advantages, such as avoiding movement and ensuring the stability and security of bolted joints. However, one of the main issues with fasteners is loosening, which can be caused by shock and vibration and lead to serious damage and structural failure. The use of machine learning techniques for bolt joint verification is limited. Hence, this study proposes a machine learning workflow centred on estimating torque by analysing raw spectral signals derived from experimental tests. This approach accounts for intrinsic variabilities in torque estimation and enhances our results performance. To enrich the experimental dataset, the study employs a technique involving the generation of synthetic datasets based on statistical moments derived from experimental data. Results show that machine learning can estimate torque in joint structures based on data collected under various conditions, improving performance with the lowest error rate.
Nonlinear performance enhancement of imperfect ring-based Coriolis Vibratory Gyroscopes
Authors: Arifin D. , McWilliam S.
Published: December 2024

The rate sensing performance of ring-based capacitive Coriolis Vibratory Gyroscopes (CVGs) is susceptible to the effects of imperfections and electrostatic nonlinearities. This research investigates the use of the nonlinear electrostatic forces to nullify these effects and replicate linear and trimmed sensor performance at increased vibration amplitudes. The approach used involves applying a suitable voltage distribution to modify the mechanical sensing mode, and a mathematical model is used to demonstrate the implementation of this scheme. For the case of 8 evenly distributed electrodes, a balancing voltage component is introduced to counteract the net forces stemming from the imperfection-induced quadrature coupling and the nonlinear frequency imbalance. The effects of the implementation are demonstrated in terms of improvements to rate sensitivity, bias rate and quadrature error of the device mechanical output. Finite element results are also included to validate the potential of this force balancing scheme. It is shown that the proposed scheme enhances device performance by reducing the bias rate and mechanical quadrature response to negligible levels and increasing rate sensitivity at increased drive amplitudes.
A numerical study on the interaction between friction and vibration in a friction-involved dynamical system
Authors: Algara Ahmad , Yuan Jie
Published: December 2024

Friction can be regarded as a dynamic variable within a dynamical system including sliding interfaces. In general, friction and vibration effects have been studied together in many studies but usually studied in one direction, primarily focusing on the effects of friction on vibration and other direction has not been widely studied, with limited attention given to their closed-loop feedback interactions in engineering applications. The presence of friction and contact surfaces introduces nonlinearity, affecting the system’s dynamic response. Moreover, oscillations applied to these structures can influence contact mechanics at friction interfaces, particularly relevant for decommissioning large-scale structures like wind turbines. However, modelling the intricate interplay between friction and vibrations is overly complex, requiring expertise from fields such as contact mechanics, tribology, and nonlinear dynamics.

The objective of the study is to investigate the mutual influences between structural vibrations and contact friction for friction-involved dynamical systems. A two-degree-of-freedom (2-DoF) lumped-parameter model has been developed to a represent friction-involved vibration system. This model incorporates the representation of contact friction using a Jenkins element, accounting for stick, slip, and separation motions occurring at the friction interface. The steady-state response of the system is calculated using the Harmonic Balance method with an alternative frequency-time scheme where its results are validated using a time domain solver. A parametric study is then conducted to examine the mutual relationship between the frictional and vibrational behaviour such as excitation level, contact stiffness, normal load, coefficient of friction, dynamic response, and the effects of vibration on friction force through a newly introduced quantity called equivalent stiffness.
A beam with an attached damping layer with an acoustic black hole profile
Authors: Wan Zhiwei , Zhu Xiang , Li Tianyun , Liu Xinru
Published: December 2024

An acoustic black hole (ABH) structure whose thickness varies according to a power law has received extensive attention in vibration reduction. However, ABH cannot be used as the primary bearing component in engineering, as the thickness reduction of ABH itself reduces its stiffness. In this article, the vibration characteristic of a beam with an acoustic black hole damping layer is studied and compared with a damping layer with uniform thickness. The beam and damping layer are based on the Timoshenko beam theory, using virtual springs to connect each other. The correctness of the proposed method is verified through the finite element method. The case studies show the proposed composite beam structure has lighter mass and lower vibration levels, compared with the beam attached with uniform damping layer.
Designing stacked multi-wedge acoustic black holes using parameter variations
Authors: Käfer Max , Dohnal Fadi
Published: December 2024

Progressive industrialization is causing noise and vibration levels to rise. The negative impact on humans and the environment calls for protective measures to mitigate the disturbing sound and vibrations. Recent developments of noise absorbing materials have included acoustic metamaterials and acoustic black holes (ABH) into the focus of attention. It was shown analytically that no sound energy can escape from the ABH if the thickness of a tapered end goes to zero and the ABH is infinitely long. The wedge-shaped ABH serves here as a basis for further research and studies on matching focusing on specific frequency ranges. The combination of the CAD-software SOLIDWORKS, the FE-software COMSOL Multiphysics and Matlab enables a robust procedure to optimize the ABH design for specific, even low, frequency ranges. Therefore eigenfrequency, time domain and energy studies have been calculated. Combining the results is showing how the ABH performs at its eigenfrequencies. As a base structure, a simple beam was added to the ABH. If the beam stays at rest and the ABH is oscillating, its performance is positive meaning that the vibrational energy is concentrated at the tip of the ABH. The main focus here is the tuning of the ABH with parametric studies using parameter variations to the frequency range of interest. The resulting eigenfrequency curves are not only showing the optimal design parameters, but also the performance of the ABH at its frequency ranges. Furthermore a case study with a pipe system was carried out of an adapted ABH, underlining its performance.
Rectangular ring resonator-based symmetrically engineered metamaterial absorber for electromagnetic interference shielding in the S and C bands
Authors: Soliman M M , Chowdhury N M , Mansor M F , Misran N , Alam T , Baharuddin M H B , Islam M T
Published: December 2024

This research aims to investigate the use of metamaterial (MM) structures in S and C bands for efficient EMI shielding. The designed MM absorber consists of four rectangular ring resonators (RRR) made of copper separated by a 1.3 mm thick FR-4 dielectric layer with dimensions of 15 mm × 15 mm and a ground layer of annealed copper with a thickness of 0.035 mm. The simulated results demonstrate two absorption peaks at 4.1 GHz and 6.8 GHz, with absorption values of 99.9% and 96%, respectively. The properties of the reflection coefficient are investigated using a circuit model of the MM absorber, and the electromagnetic wave absorption mechanism is further studied by examining the surface current, H-field, and E-field distributions at absorption peaks. The metamaterial (MM) absorber exhibits almost perfect absorption across a significant angle of incidence and polarisation angle up to 60 degrees. The suggested MM design provides dual-band shielding characteristics with a -10 dB reflection coefficient (S11) at 4.0-4.14 GHz and 6.83-6.89 GHz. Furthermore, the Metamaterial (MM) absorber offers a shielding efficiency of > 20 dB in all bands, according to the theoretical analysis. The MM’s 99% absorption and shielding capability makes it suitable for a wide range of high-potential applications.
Design and Fabrication of High-Gain Dual Linearly Polarized Patch antenna at 28 GHz
Authors: Mohd Hamzah Siti Zainab , Abdul Malek Norun Farihah , Mohamad Sarah Yasmin , Mohd Isa Farah Nadia
Published: December 2024

Extensive research on millimeter-wave frequency bands is currently in rapid development throughout the world, specifically at an operating frequency of 28 GHz, and Malaysia is no exception. The most conventional patch antennas covered a limited polarization feature of single polarization of radiated beam signals. In order to meet the high demands of network users with a higher data rate, the radiated beam signal coverage should be as wide as possible to ensure the stability and consistency of the received signals for the users. This leads to the development of the dual polarization feature of single-layer antenna design. In this work, a dual element (70 x 70 mm2) patch antenna at 28 GHz has been designed using CST Studio Suite and fabricated using Rogers RT5880. The antenna has been oriented to the right (+45°) and to the left (-45°) from the normal plane to realize a dual linear polarization state. The simulation and measurement results show that the reflection coefficient obtained for all antennas is less than -10 dB. The simulated and measured radiation patterns of the antennas are also shown in this paper. It is observed that the proposed antenna achieves a dual-polarized state with a higher gain of 11.16 dBi, compared to 4.97 dBi for a single patch. This dual-polarized antenna can be applied in various applications, particularly for MIMO and 5G mobile communication networks.
Dielectric and microwave properties of latex rubber composites filled with various carbon-based fillers
Authors: Ayob Nur Syuhada , Yahaya Nor Zakiah , Aqiman Mohamad Zul , Ramli Ramzun Maizan , Sulaiman Shukri , Mahmud Mohd Nazri , Rahim Hasliza A
Published: December 2024

This study investigates the dielectric and microwave properties of latex rubber composites filled with various fillers, aiming to enhance their performance in applications such as electromagnetic interference (EMI) shielding, microwave absorption, and electronic devices. Composites were prepared by incorporating different types of fillers, including activated carbon-based rice husk (AC-RH), graphite (G), bamboo charcoal (BC), and calcium carbonate (CC). The dielectric properties were evaluated with a commercial coaxial probe (Agilent 85070E), and the microwave properties were determined with an insulated monopole sensor operating in the 2 to 20 GHz frequency range. The results showed that fillers significantly improved the dielectric and microwave properties of rubber composites, with AC-RH exhibiting the greatest improvement. AC-RH has the lowest reflection loss, -13 dB at 10 GHz.
Nutrient Content of Water at Different Landuse in Peatland in Central Kalimantan, Indonesia
Authors: Sulistiyanto Y , Jaya A , Zubaidah S , Sustiyah S , Jovani-Sancho J
Published: December 2024

Research on water in four different landuse in peat swamp area in Kalampangan Central Kalimantan, Indonesia was carried out and water was sampled every one month from May 2018 to April 2019 and analyzed for pH, soil electrical conductivity (EC) and total content of Ca and Mg. Aim of the research is to obtain the different in nutrient concentration in different land use. Methods, six permanent locations in each land use were used to gather water samples. The landuse were established in (a) Peat swamp forest (b) Jelutung forest (c) Agriculture area and (d) Oil Palm. Water samples were taken at 100 cm below the surface at each peatland site. Result show that water in Forest is very acid with average pH (4.24 ±0.48), Jelutung forest (4.68 ±0.33), Agriculture area (4.69 ±0.62), and Oil Palm 4.67 ±0.38). Soil Electrical Conductivity (EC) in Forest is the lowest with average 0.32 ±0.11 mS.cm -1, Jelutung forest (0.56 ±0.36), (c) Agriculture area (0.93 ±0.52), and (d) Oil Palm (0.52 ±0.19), Similary to Soil Electrical Conductivity (EC), Ca content in water in Forest is the lowest with average 8.20 ±4.54 mg.l-1, Jelutung forest (19.72 ±10.42), (c) Agriculture area (23.60 ±11.54), and (d) Oil Palm (17.45 ±8.27). Mg content in water in Forest is the lowest with average 0.51 ±0.40 mg.l- 1, Jelutung forest (0.93 ±0.47), (c) Agriculture area (2.77 ±1.57), and (d) Oil Palm 0.82 ±0.59). The highest nutrient cotents of Ca and Mg in water was Agriculture area and the lowest in Forest area. Furthermore, nutrient contents of water at each landuse during dry season was higher than wet.
CH4 Emissions on Smallholder Plantations in The Tropical Peatlands of Central Kalimantan, Indonesia
Authors: Sustiyah  , Dohong S , Ariani N P , Soemamo  , Jaya A , Sulistiyanto Y , Damanik Z , Umbing R A , Surawijaya P
Published: December 2024

The development of peatlands is considered a contributor to greenhouse gas (GHG) emissions originating from land clearing, burning, and land management. Greenhouse gas emissions are one of the factors causing climate change and global warming. One of the main greenhouse gas components of peatlands is methane. This study aims to determine the effect of conversion of peat land to smallholder plantations on the amount of CH4 emissions and the water table. This research was conducted in the smallholder farming at Kalampangan Village, Palangka Raya City, Central Kalimantan Province, Indonesia. The results showed that the conversion of peat land to smallholder plantations had an effect on CH4 emissions and the water table. CH4 emissions in oil palm plantations are higher and the water table is deeper than in dragon fruit plantations. CH4 emissions in oil palm plantations were 1.66-53.18 mg CH4 m−2 hours−1 and in dragon fruit orchards it ranged from 12.43-35.00 mg CH4 m−2hours−1. The water table values in oil palm plantations ranged from (-145.33- -196.67) cm and in peat land dragon fruit gardens ranged from 115.00-167.17 cm. CH4 emissions on peatlands before conversion were 0.42-3.92 mg m−2hours−1 and the water tabel value is (-69.48-+22.40) cm in rainy season conditions. This condition shows that the location of the smallerholder plantation land is in anaerobic conditions. The soil temperature in the chamber in the peatlands of oil palm plantations ranges between 27.20-38.60 °C, and in the peatlands of dragon fruit plantations ranges from 34.09-39.45°C. The soil temperature around the chamber in the peatlands of oil palm plantations ranges from 27.81-37.17 °C, and in the peatlands of dragon fruit plantations ranges from 32.51-38.59 °C.
Growth of 7 (Seven) Years Old Red Meranti (Shorea leprosula Miq.) in the Palangka Raya University Seedling Seed Orchard
Authors: Sudomo MFA , Pidjath C , Kalawa D A
Published: December 2024

This research aims to analyze the growth and identify peat soil chemical properties under the Shorea leprosula Miq.stand. This research was carried out at the Palangka Raya University Seedling Seed Orchard (SSO) which is located in the Green Campus Area of Palangka Raya University. The sampling method in the field uses a purposive sampling method to take the first tree sample on each route and continue with Systematic Sampling, by measuring 10 tree samples on each route, the total number of trees measured on all routes are 300 trees. Meanwhile, to identify soil by taking soil samples in 2 plots, For soil chemical characterization analysis. Based on research results S. leprosula growth annual increment in diameter, height, and volume were 0.99 cm. year-1 66.96 cm year-1 0.0023 m3. year-1 respectively. Soil fertility criteria under the Meranti Merah stand, it can be seen that the only P content is very high in the soil, while the soil pH has very strong acid and several other elements have low and shallow criteria levels.
Energy Intensity and Employment: evidence from Latin American countries
Authors: Vilema-Escudero Segundo F. , Ruiz-Martínez Miguel , Manya-Orellana Marlon , Arguello-Núñez León
Published: December 2024

This study investigates the relationship between energy intensity and employment in 13 Latin American countries, differentiating between countries with and without OECD relations. Using a panel data regression model from 2000 to 2017, the analysis reveals that energy intensity negatively impacts employment, particularly in OECD-related countries. The study also examines the moderating role of economic performance and foreign direct investment (FDI) in this relationship. While economic growth is associated with higher energy efficiency, it does not consistently mitigate the negative effects of energy intensity on employment. Similarly, FDI shows a limited impact in moderating the energy-employment relationship. These findings highlight the need for comprehensive policies that promote both energy efficiency and quality employment in diverse economic contexts. Future research should explore the influence of technological innovation and sector-specific factors on the energy-employment relationship in lower-income countries.