bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of Thermal Wall and Velocity Slips on Non-Darcy MHD Boundary Layer Flow of a Nanofluid over a Non-linear Stretching Sheet
Authors: Bansal Sham , Kumar Ashok , Pal Jai , Goyal Ishu , Singh Negi Anup
Published: December 2024

This study investigates the characteristics of magnetohydrodynamic nanofluid flowing via a non-linearly stretched surface within a porous media along with thermal and velocity slips. The similarity transformation is implemented to derive non-dimensional ordinary differential equations from partial differential equations. The finite difference Keller box implicit method yields the numerical solutions. Notably, our findings reveal the intricate influence of several factors, such as velocity slip factor, permeability parameter, thermophoresis parameter, thermal slip factor, Brownian parameter, magnetic parameter and stretching factor on temperature, concentration and velocity, also unveiling nuanced insights into the enhancement of mass and heat transfer attributes. The finding shows that the concentration and temperature of the nanofluid are enhanced and reduced respectively on increasing the thermal slip factor. Further, both mass and heat transfer rates decrease with increasing thermal slip, while the influence of skin friction coefficient is negligible. Further, Both concentration as well as temperature increase on enhancing velocity slip parameter, but opposite behaviour has been observed for the velocity profile. Further, for the higher value of velocity slip, the skin friction coefficient and the rate of heat transfer are increased. While, the mass transfer rate decreases. Furthermore, As the permeability increases, temperature and velocity profiles both indicate an upward trend, which is an acceptable result because more permeability propels more flow and low permeability induces weak flow in the system. The achieved results are depicted graphically.
Parametric Properties of New F-Divergence Measure
Authors: Naresh Saraswat Ram , Sharma Anulika , Agarwal Vandana
Published: December 2024

F-divergences are a class of functions that quantify the difference between two probability distributions. They are widely used in statistics, machine learning, and information theory. New F-divergences typically refer to variations or extensions of existing F-divergences, introducing additional parameters to customize their behavior or properties. The parametric properties of a new F-divergence measure would depend on the specific form of the divergence and the parameters introduced. In this paper, discussed the parametric properties of new f-divergence functional. This measure is also known as Jain and Saraswat measure which is established in 2012 and 2013. The applications of this measure in the form of series using the properties of convexity have been established.
Active vibration control of an induction motor with sleeve bearings and electrodynamic actuators between motor feet and steel frame foundation regarding electromagnetic excitation
Authors: Werner U
Published: December 2024

The paper presents a theoretical analysis of active vibration control of an induction motor with sleeve bearings and electrodynamic actuators between motor feet and steel frame foundation, where the vertical vibration velocities of the motor feet are lead back to separate controllers. Based on a 2D model, the mathematical coherences of the controlled vibration system are presented, as well as a numerical example of a 2-pole induction motor. The threshold of vibration stability is calculated as well as frequency responses regarding bearing housing vibrations caused by electromagnetic forces in the air gap of the induction motor, due to a static magnetic eccentricity between rotor and stator. Also the actuator forces are analyzed. With this analysis, the effectiveness of the developed active vibration control system can be demonstrated.
ANSYS Modelling of Piezoelectric Smart Beam using Ritz Vector Method and Sub-structuring Analysis
Authors: Jackson Abasiodiong , Fletcher Simon , Ariaga Nemwel
Published: December 2024

Finite element analysis (FEA) is an important tool for smart structure modelling, particularly in the context of piezoelectric beams. A key challenge in such modelling is the derivation of electro-elastic coupling, which explains how these structures respond mechanically to electrical loading. Traditional methods rely on intricate shape functions that encompass both electrical and mechanical degrees of freedom, rendering the process complex.

In this study, an innovative approach—the so-called Ritz vector method— which facilitates modelling of the system based on loading effect is implemented to simplify electro-elastic coupling calculations. The method previously applied in MSC Nastran with a thermal analogy system and validated experimentally is now implemented in the widely accessible ANSYS software. By harnessing ANSYS’ robust piezoelectric capabilities and sub-structuring analysis for matrix extraction, the essential piezoelectric coupling and dielectric matrices are derived for piezoelectric stack and patch actuator driven cantilevered beams.

Subsequently, state space models of these smart structures are constructed using MATLAB and results are compared with ANSYS FEA static and dynamic response. Active Disturbance Rejection Control (ADRC) was implemented on the modelled beams and results show significant suppression of free vibration due to impulse excitation of the tip. This work portrays the potential of the Ritz vector method, a powerful yet underexplored tool that simplifies electro-elastic coupling calculations for piezoelectric smart structures.
Passive reduction of reflected surface acoustic waves
Authors: Schoenebeck D , Vanko G , Kromka A , Dohnal F
Published: December 2024

Lab-on-a-chip devices have been widely developed but are still considered as an emerging technology for medical and environmental field monitoring. In addition to a miniaturized sensor, a microfluidic lab-on-a-chip (LOC) needs an actuator in the same size scale. One promising actuation concept is the acoustic streaming realized by surface acoustic wave (SAW). The generated waves are confined at the substrate surface which leads to out-of-plane movements with high directional accelerations. Once the energy is coupled into a fluid, a streaming effect is initiated. However, reflections at the substrate edges can significantly impede the occurrence of SAW. To prevent reflections, damping structures need to be put in place. Nonlinear tapered ends are a prospective reflection mitigation technique in the field of structural dynamics. In this study, we report the computational investigation of tapered ends for reducing the edge reflections in micromechanical SAW devices. Test cells for finite element analysis via COMSOL Multiphysics® were extended to virtual prototypes of physically realistic SAW devices. The results showed that the implementation of tapered ends significantly reduced parasitic reflections and increased the articulation of surface displacements by at least two orders of magnitude. These findings demonstrate the effectiveness of incorporating tapered ends into finite substrate models for SAW devices.
Simulated bubble oscillations in gearboxes for electrified vehicles
Authors: Hafner Lukas , Holzbrecher Jonas , Wiedenmann Matthias , Hieronymus Timm , Schwarzer Steffen , Dohnal Fadi
Published: December 2024

The shift in drive concepts from internal combustion engines to electrified vehicles is changing the demands on drive machines and their associated subsystems. A well-known phenomenon in oil-lubricated transmissions is the unavoidable mixing of air with the oil during operation. The so-called oil-air-dispersion that occurs can be measured on the basis of the air bubble size and air bubble size distribution in the oil in a dispersion spectrum that occurs depends on geometry, speed and torque. Due to the increase in speed by several orders of magnitude in electrified vehicles, the speed- and torque-based vibration excitation of the transmission changes both in the excitation frequencies and in the excitation amplitudes. This brings physical effects into focus that previously played no role in drive technology. One of these physical effects is vibration-induced cavitation, which generates high pressures and temperatures and has negative effects on both the oils used and the mechanical components. The vibration behavior of air bubbles in oil is calculated using the Gilmore model from a realistic bubble size and relevant excitation frequencies.
An adaptive reduction method for viscoelastic structures without approximation on viscoelasticity
Authors: Zhang Shuyang , Belle Lucas Van , Devriendt Hendrik , Desmet Wim
Published: December 2024

Viscoelastic materials are often encountered in engineering applications, such as bonded assemblies, polymer structures, or structures with damping treatments. To simulate the dynamic behavior of large mechanical systems with viscoelastic materials, finite element (FE) models are commonly employed. However, the large size of these models can lead to significant computational costs, making model order reduction (MOR) often a necessary step for improving the computational efficiency. Recently, an adaptive Taylor-based second-order Arnoldi (AT-SOAR) algorithm was introduced, which addresses the frequency-dependency of viscoelastic materials. However, due to the Taylor-based approximation used in the viscoelastic behavior modelling, the resulting reduced order models (ROMs) may leave room for improvement, both from an accuracy as well as from an efficiency point of view. Hence, this work proposes a two-layer Krylov subspace (TLK) method that circumvents the viscoelastic model approximation. Additionally, a sequenced collection approach is used to augment the reduction basis from these two layers of Krylov subspaces. For automating ROM generation in line with specific error criteria, the TLK method is integrated with the adaptive algorithm in AT-SOAR (A-TLK). The proposed method is demonstrated through an adhesive single-lap model example, showing that A-TLK can generate smaller, more efficient ROMs compared to AT-SOAR under the same error tolerance.
The contribution of higher order modes to shock response spectra
Authors: Dubber Kyle , Ferguson Neil , Waters Timothy
Published: December 2024

The shock response spectrum is a widely used design tool that engineers use when assessing the severity of transient excitation on a structure. The shock response spectrum is typically defined as the peak response of a series of single degree-of-freedom (DOF) oscillators each with a different natural frequency. For structures representable by a single DOF system, such is the case when only a single mode dominates the response, the shock response spectrum can be used to evaluate this response directly and a brief review of the existing accepted metrics is presented. In general, the response of many structures may comprise contributions from higher order modes leading to inadequate predictions from the shock response spectrum, especially for acceleration responses. In such cases a form of shock response spectrum can be obtained that accounts for all modes of vibration but as a function of shock duration. However, a multi-modal model of the structure is then required and its shock response obtained numerically over a range of shock durations which can be computationally expensive and less amenable to physical interpretation.

This paper adopts a previously proposed modal approach to obtaining the shock response of systems with contributions from higher order modes, in which the transient response is calculated for each mode in turn which are then superposed. A key question that arises is the number of modes that need to be retained in the summation. Two numerical case studies are presented which explore modal convergence for displacement, velocity and acceleration shock response spectra. Results suggest that a priori mode selection is not generally possible although inspection of the mode shapes can offer guidance. However, the benefit of the modal approach to interpretability of the results is illustrated.
Vibration-Based Crack Detection in Plates Using Natural Frequency Degradation.
Authors: Satpute A A , Kennedy D , Featherston C A , Kundu A
Published: December 2024

Structural cracks reduce the performance and service life of buildings, bridges, and aircraft structures, leading to catastrophic failures resulting in economic losses and fatalities. To avoid such consequences, regular health monitoring and maintenance is required, especially for critical structures that carry high levels of dynamic and fatigue loading and whose failure would be catastrophic. Many techniques are available for structural health monitoring, including visual inspection, ultrasonic testing, acoustic emission, magnetic field, and vibrational-based methods. Any damage causes degradation in the natural frequencies and vibration modes of a structure, which are considered in vibration-based methods to characterize the damage. The focus of this research is to develop a more efficient method for the detection and characterisation of arbitrarily oriented surface cracks in isotropic plates, in terms of five parameters, namely the longitudinal and transverse location, length, depth and orientation. To achieve this objective, an analytical solution based on strain energy is used to generate synthetic data that quantifies changes in the natural frequencies for different crack locations and intensities based on noise-free simulation. The inverse problem, i.e. the determination of the crack parameters based on measured changes in natural frequencies can then be solved based on the use of synthetic data with a gradient based optimisation technique.
Modelling and Simulating the Primary Vertical Hydraulic Railway Dampers DISPEN
Authors: Mwakitabu Simon , Ichchou Mohamed , Bareille Olivier , Nechak Lyes , Trabelsi Amin , Valette Lionel
Published: December 2024

The train’s bogie consists of suspension systems and mechanical links. The hydraulic damper is a crucial part of the suspension system to ensure safety and comfort. The primary vertical damper mostly linear is responsible for reducing vibrations transmitted from the rails to the wheels of a High Speed Train. During the damper design, certain geometric parameters such as the diameter of the valves, spring constant, preload force and valve orifice diameter are adjusted to achieve the desired force-velocity characteristic by DISPEN. This process can be both cumbersome and costly in terms of time and money. A non-linear physical model is developed solving stiff ordinary differential equations predicting the dynamic pressure variations inside the damper and the dynamics of the piston valves caused by external excitation. New methods of tangling numerical discontinuities have been discussed and pressure losses have been deployed to predict the opening of the valves. The model is then validated against stringent criteria with the test-bench results and used for optimising values to obtain suitable force-velocity characteristics for integrated dynamic calculations.
Nonlinear Dynamics of Atomic Force Microscopy with Viscoelastic Term and Casimir force interactions: An Overview
Authors: Ribeiro Mauricio A. , Balthazar José Manoel , Tusset Angelo M. , Hilson  , Daum H. , Kurina Galina A. , Kirrou Ilham
Published: December 2024

Atomic force microscopy (AFM) is an important tool for analyzing the atomic surface of synthetic or biological samples. The atomic force microscopy device consists of a built-in microcantilever that contains a nano tip at its free end. This nano tip finds the surface of the sample which is scanned for data collection. Vibrations caused by irregularities on the sample surface are collected using a laser that reflects from the microcantilever to a photodiode. In this work, we explore the nonlinear dynamics of the mathematical model, which describes the one-dimensional torsional behavior of the microcantilever motion. The term viscoelasticity and the Casimir force were considered, and we established the set of parameters that present chaotic behavior and thus, proposed control techniques to suppress chaos. However, we explored the nonlinear dynamics behavior of a one-dimensional nonlinear AFM model with the twist of the tip of the microbeam containing the analysis tip. And so, we analyze the contribution of the Casimir Force and the viscoelasticity term in the model considered. The aim of this work was to analyze the regions in which the system is in a chaotic and periodic regime, choosing the initial conditions, using classical tools (Lyapunov Exponent, Bifurcation Diagram, Poincare Map, etc.). Determining such regions supports improvements and proposals for future control projects to suppress chaos. Such suppression allows irregularities in the movement of the microcantilever to be periodic, which can reduce noise in sample analyses.
Improving the frequency stability of capacitive ring-based Coriolis Vibrating Gyroscopes
Authors: Arifin D. , McWilliam S.
Published: December 2024

MEMS capacitively operated ring-based Coriolis vibratory gyroscopes are used to measure angular rate. Under standard operating conditions the ring is driven into resonance and Coriolis coupling generates a response that is proportional to the applied angular rate. In practice capacitive devices are susceptible to electrostatic nonlinearities due to narrow capacitive gaps which potentially degrades the quality of the measurement. One issue is that large amplitude drive responses yield multi-harmonic response which distorts the sense output causing the rate output to vary periodically (i.e. frequency instability). In this research it is shown that this frequency instability can be negated relatively easily by incorporating additional harmonics in the drive force. To implement such an approach it is necessary to use a voltage distribution to generate the appropriate electrostatic forces to eliminate or reduce the multi-frequency mechanical response of the ring. A mathematical model is used to quantify the effects of the implementation of the voltage distribution in terms of discrete Fourier transform of the ring response and the calculated Allan deviation. It is shown that the proposed implementation approximates linear behaviour by reducing the multi-harmonic response by orders of magnitude.
Design and characteristic analysis of quasi-zero stiffness inertial actuator
Authors: Ji Zhiyuan , Yang Tiejun , Wu Lei , Xu Yang , Li Xinhui , Zhu Minggang
Published: December 2024

In order to solve the problem of low frequency vibration control more effectively, a new type of inertial actuator is proposed in this paper, which is different from the conventional type in that the linear stiffness is replaced by the quasi-zero stiffness. In this design, the structure mainly consisting of a horizontal spring and connecting rod provides negative stiffness to offset the positive stiffness of the vertical spring, which not only ensures sufficient static load capacity, but also reduces the dynamic stiffness of the mass near the equilibrium position. In this study, a restoring force characteristic of the actuator (i.e., the influence of the quasi-zero stiffness structure on the mapping relationship between the restoring force and displacement) is investigated. Then the nonlinear differential equations of the quasi-zero stiffness actuator are derived. The dynamic characteristic of the actuator is discussed based on the harmonic balance method, and the accuracy is proved by numerical verification. The dynamic simulation results show that the quasi-zero stiffness structure can effectively reduce the natural frequency of the actuator, and its performance in low frequency band is better than that of the corresponding linear actuator.
An inclined beam-based vibration isolator design to attain quasi-zero-stiffness characteristics
Authors: Yadav Vinod , Jena Dibya Prakash , Pandey Sharat
Published: December 2024

A linear spring element combined with a nonlinear spring element has low dynamic stiffness and high static stiffness. In this work, a quasi-zero stiffness (QZS) vibration isolator based on positive stiffness and negative stiffness characteristic is explored. Using finite element simulation, the nonlinear stiffness of the inclined beam caused by the buckling effect and the linear positive stiffness of the circular arc beam is examined. The combination of these two beams delivered high static and low dynamic stiffness. The static characteristic is performed to obtain the operational displacement range. The parametric study illustrates the effect on force displacement characteristics due to variation in thickness of circular arc beam. The dynamic characteristic of the QZS isolator is studied under different damping ratio and excitation. Additionally, a stability study is carried out to identify the frequency response curve’s unstable area. Combination of inclined and circular arc beam may be a good candidate to fulfil desired requirement to achieve a wide frequency range of isolation.
The use of geometrical nonlinear local resonators to enhance the vibration control performance of metamaterial structures
Authors: Santo D R , Claeys C , Deckers E , de Oliveira L P R
Published: December 2024

Metamaterials has become an exciting solution for structural noise and vibration reduction in many engineering applications. Acoustic metamaterials are structures built using repetitive assemblies of identical elements to explore either Bragg-scattering or localized resonance to control mechanical waves. They present frequency bands in which waves do not freely propagate, named bandgaps, allowing acoustic and vibration attenuation at one or multiple targeted frequency ranges. If properly designed and implemented, the inclusion of a nonlinear stiffness can result in resonance frequency shifts that broaden the attenuation frequency band. This work investigates the influence of an array of lightweight nonlinear local resonators (NLR) realized via additive manufacturing on the low-frequency bandgap formation of a metamaterial beam. The NLR uses the high-static-low-dynamic stiffness (HSLDS) concept, which introduces geometric nonlinearity. The proposed model is validated through simulation and experimental analysis. The NLR results in a broadened and shifted attenuation band to lower frequencies without the necessity of adding extra mass to the resonator. This investigation contributes to understanding improvements provided by nonlinear elements for vibration control in metastructures.
Passive earthquake vibration mitigation of a steel tower crane by joint dampers
Authors: Solazzi L , Rustighi E
Published: December 2024

This research presents numerical findings on the seismic response of a tower crane employing anti-seismic joint dampers at its base. The study demonstrates that these damping elements effectively mitigate dynamic actions induced by seismic forces, reducing stress magnitudes by approximately 10%-15% without increasing overall displacement. Moreover, static loading configurations reveal minimal differences in mechanical behavior between cranes with and without damping elements, indicating negligible displacement increases when utilizing damping mechanisms. The research highlights the potential of damping elements to mitigate seismic effects without significantly altering the crane’s natural frequencies. Overall, the results underscore the importance of implementing damping systems to enhance seismic resilience in crane structures, promising advancements in construction safety and efficiency.
Utilising computational fluid dynamics to investigate damping effects in fluid inerter-based vibration control devices
Authors: Dogan Hakan , Tamer Aykut , Enes Salman H. , Deastra Predaricka
Published: December 2024

Over the past two decades, inerters have attracted significant attention in structural control. Numerous applications in engineering fields have proposed employing inerter-based control devices to mitigate structural vibrations. While theoretical studies have demonstrated performance enhancements, practical implementation and experimental validation have remained limited primarily due to cost and technical challenges. Studies conducted with the physically built inerters have showed discrepancies between theoretical model of the inerter and its actual performance because of factors such as nonlinearities and damping effects. Computational Fluid Dynamics (CFD) can provide a more accurate model of the inerter without the need for costly experimental setups. This paper presents a CFD analysis aimed at evaluating the actual performance of a fluid inerter-based control device for vibration mitigation of single degree of freedom (SDOF) structure. The accurate modeling of the inerter obtained through CFD is used to evaluate the performance of the inerter-based control device. The results reveal an important difference between vibration mitigation performance when comparing the ideal theoretical model and the CFD model.
The effect of joint uncertainty on scattering properties using a hybrid methodology
Authors: Kara M , Ferguson N S
Published: December 2024

Joint uncertainty is a subject of much interest in structural dynamics’ research, as joint behaviour potentially becomes more significant at higher frequencies. Therefore, an accurate determination of the scattering properties of uncertain joint elements for wave-based methods becomes more important on the subsequent prediction sensitivity. For this reason, this study examines the resulting scattering properties (reflection and transmission efficiencies) due to uncertain joints using a hybrid methodology. The scattering is calculated for a beam-to-beam joint via a combined hybrid Wave Finite Element and Finite Element (abbreviated as hybrid WFE) model, while Polynomial Chaos Expansion is utilized for the uncertainty modelling. It is assumed that the joint has a uniformly distributed uncertain thickness and loss factor. The results are compared to analytical transmission efficiencies and Monte Carlo simulations. The results show that the uncertainty in the joint does not become more evident as the frequency increases as expected, and the proposed methodology successfully models the joint uncertainty problem.
Physics-Enhanced Machine Learning: a position paper for dynamical systems investigations
Authors: Cicirello Alice
Published: December 2024

This position paper takes a broad look at Physics-Enhanced Machine Learning (PEML) - also known as Scientific Machine Learning - with particular focus to those PEML strategies developed to tackle dynamical systems’ challenges. The need to go beyond Machine Learning (ML) strategies is driven by: (i) limited volume of informative data, (ii) avoiding accurate-but-wrong predictions; (iii) dealing with uncertainties; (iv) providing Explainable and Interpretable inferences. A general definition of PEML is provided by considering four physics and domain knowledge biases, and three broad groups of PEML approaches are discussed: physics-guided, physics-encoded and physics-informed. The advantages and challenges in developing PEML strategies for guiding high-consequence decision making in engineering applications involving complex dynamical systems, are presented.
Vibroacoustic response of a heavy fluid loaded plate with ABH stiffeners
Authors: Martins Daniel , Karimi Mahmoud , Maxit Laurent
Published: December 2024

Stiffened structures are essential for a wide range of engineering applications including aeronautics, marine and rail systems. Adding stiffeners to a host structure leads to generation of Bloch-Floquet waves, which are induced by the interaction between the flexural waves in the host structure and the flexural/torsional waves in the stiffeners. These waves could generate unwanted noise and vibrations which should be mitigated. Acoustic black holes (ABHs) are widely used as a passive-control approach to mitigate vibrations of elastic structures. This study aims to use ABHs integrated as stiffeners for a fluid-loaded plate. Hence, the host structure is not modified, and its structural integrity is maintained. A heavy fluid-loaded infinite plate with periodic ABH stiffeners under a line force excitation is considered (i.e., a two-dimensional model). To obtain the vibrocoustic response, the system is modelled using the COMSOL Multiphysics®. The effectiveness of the ABH stiffeners in mitigating the vibration and noise from the fluid loaded plate is examined.
Modelling the una-corda effect in pianos
Authors: Valiente Pablo Miranda , Squicciarini Giacomo , Thompson David , Norris David O. , Hernandez Cesar
Published: December 2024

Most notes of a piano are fitted with two or three strings that, in normal playing conditions, are simultaneously struck by the hammer. In grand pianos, the una corda pedal offers alternative musical effects, notably a softer and duller tonal quality. This pedal’s operation is linked to a lever system that displaces the action to one side causing the hammer to hit only one-out-of-two or two-out-of-three strings, thereby altering the sound. Meanwhile, the other strings of the same note undergo sympathetic vibration, owing to their structural connection through the bridge. This paper introduces a dynamic model that replicates the effects of the una corda pedal. It consists of a state-space scheme, serving as a framework to couple the dynamic behaviour of the various components. Stiff-string models describe the strings’ vibration in three dimensions while a reduced modal model captures the dynamics of the soundboard. Results show how the string vibration and the force transmitted to the soundboard are affected by applying hammer excitation to individual or multiple strings. When all strings are struck, the transverse vibration shows beating. This effect is audible and evidenced in the spectrograms, where the amplitude of partials oscillates over time. In the una corda case, the force exerted on the bridge by the passive string increases initially with time, and its contribution to the overall transmitted force is smaller. However, there is no beating, the decay is more even, and the spectrograms do not show irregularities over time.
Numerical analysis of an omnidirectional and polarization-insensitive broadband metamaterial absorber based on a quadcopter-shaped structure
Authors: Rahman M , Soliman M M , Mansor M F , Misran N , Alam T , Sahar N B M , Islam M T
Published: December 2024

A broadband metamaterial absorber with a unique symmetrical quadcopter-shaped resonator, operating in the visible spectrum between 400 and 800 nm is proposed in this work for effective solar energy harvesting. A SiO2 substrate, which is likewise reinforced by a tungsten ground plane, is utilized to print this centrally symmetrical structure. Across the whole visible band, the numerical findings show an extraordinary absorption exceeding 90% while having an average absorption of 97.2%. Furthermore, the structure shows a high photothermal conversion efficiency (PTCE) across a broad temperature range in solar thermophotovoltaic (STPV) systems. Notably, strong functionality and polarization independency across a large range of incident angles, indicates its promise as an adaptable solution for developing broadband optical applications and solar cell technologies.
A broadband substrate integrated waveguide fed dielectric resonator antenna with U-slot for 5G-NR Band
Authors: Nasir Nida , Jamaluddin Mohd Haizal , Shahadan Nor Hidayu
Published: December 2024

In the proposed design, a Substrate Integrated Waveguide (SIW) feeding mechanism is utilized in conjunction with a higher-order mode Dielectric Resonator Antenna (DRA), which is excited by a U-slot aperture on the top side of the ground plane. This structure is aimed for 5G millimeter-wave bands, N257, and N258. Both sides of SIW are clad with 0.035mm copper with a permittivity of 2.2, Rogers 5880 is used as substrate. In contrast, DRA has a permittivity of 10. The design achieves a notable impedance bandwidth of 25-31.12 GHz (6.12 GHz or 21.8%) due to the excitation of multiple resonances of DRA modes. It delivers high gain values of 8.5 dBi at 25.8 GHz, 8.9 dBi at 27.5 GHz, and 7.2 dBi at 30 GHz, with radiation efficiency exceeding 98% within the resonance band. The radiation patterns demonstrate good co-polarized performance, validating the broadside transmission. All simulations were conducted using Ansys HFSS version 2023.
Gain Enhancement in Antipodal Vivaldi Antennas using Parasitic Elements and Metamaterials
Authors: Johari Safpbri , Mohd Yassin Mohd Najib , Ismail Arif Marwardi , Nurhayati Nurhayati
Published: December 2024

Conventional Antipodal Vivaldi Antenna (AVA) suffers from limited gain, especially at high frequencies. This paper addresses this challenge by proposing a compact AVA design of 1.28λ0 × 0.91λ0 × 0.18λ0 at 3.5 GHz that achieves significant gain enhancement. The design utilizes strategically placed parasitic elements to manipulate current distribution and a custom metasurface lens to optimize the wavefront. Simulations demonstrate substantial gain improvement compared to a conventional AVA across a wide frequency range. This approach offers a promising solution for high-gain, wideband AVA suitable for long-range and focused signal transmission applications.
Generating Orbital Angular Momentum Waves with 3-bit Resolutions of the Reflective Metasurface
Authors: Johari Safpbri , Mohd Yassin Mohd Najib , Ismail Arif Marwardi , Amri Muhammad Miftahul , Ali Norshamsuri
Published: December 2024

In this paper, we introduce the metasurface (MS) designed to generate Orbital Angular Momentum (OAM) within the 5.6 GHz frequency range. The basic unit comprises hexagonal patches, ensuring a full 360° phase cycle. This distinctive design enables the realization of quantized phases, enhancing the overall efficiency of the MS. Using topological optimization methods for unit organization, we show 3-bit resolutions. The OAM MS proposed in this study consists of 16 ×16-unit cells. Simulation findings demonstrate how well the MS generates a first-order OAM beam. The potential applications of this proposed MS design extend to wireless communication systems. By enabling controlled OAM generation at 5.6 GHz, this innovation holds promise for advancing communication technologies, contributing to the evolution of wireless systems.
Realization of Plasma Antenna using U-Shaped Compact Fluorescent Lamp
Authors: Jusoh M T , Lafond O , Colombel F , Himdi M
Published: December 2024

This paper introduces a novel plasma antenna utilizing a U-shaped compact fluorescent lamp (CFL) as the radiating element, excited by an alternating current (AC) supply. Unlike conventional designs, the coupling sleeve in this plasma antenna is positioned beneath the ground plane, reducing unwanted radiation when the plasma is deactivated. Two prototypes were fabricated, varying only in height (35.7 mm and 77 mm). Measurements at 900 MHz revealed significant differences in radiation patterns between ON and OFF states, indicating effective radiation in the ON state. However, at 450 MHz, only the shorter antenna (35.7 mm) exhibited acceptable performance. The results demonstrate that a U-shaped CFL can serve as an efficient plasma antenna, with performance comparable to classical dipole antennas within the tested frequency range.
On Thin Flexible Wideband Printed Antenna for Sub-6 GHz Wearable Applications
Authors: Afroz S , Al-Hadi A A , Azemi S N , Hoon W F , Padmanathan S , Isa C M N C , Sahoo B C , Loh Y S , Tung L H , Lim L M , Samsudin Z , Mansor I , Soh P J
Published: December 2024

Body Area Networks (BANs) have gained significant popularity in recent years, leading to a substantial rise in the demand for wearable antennas. Printed antenna on the flexible substrate can be an excellent choice for wearable since it can be used as a smart garment (i.e. shirt, T-shirt, or jacket). Unlike rigid antennas, the fabrication and measurement procedures for wearable antennas are particularly critical and sensitive. In BANs, the presence of the human body presents another significant challenge such as structural deformation (like bending). This paper has provided an overview of the fabrication process and measurement considerations for printed flexible wearable antenna. It also compared these antennas with conventional copper tape antenna across all aspects. Bending deformation of the printed antenna is performed as well to ensure the antenna’s functionality under such circumstances.
Mitigating Soil Greenhouse Gas (GHG) Emissions: Organic Agroforestry Practices in Previously Degraded and Abandoned Tropical Peatlands
Authors: Darusman T , Husna Z S , David A , Adventiaputri A , Lestari D P
Published: December 2024

Degraded and abandoned tropical peatlands are highly susceptible to forest fires, which can significantly contribute to greenhouse gas (GHG) emissions. One potential solution to mitigate this problem is the implementation of agroforestry practices. However, there is limited data on soil-based GHG emissions from smallholder agroforestry practices. To address this gap, our study aimed to quantify and compare soil-based GHG emissions at two experimental sites of organic agroforestry practice, with and without intercropping. The non-intercropping system only grows wood-based perennial commodities. In contrast, the intercropping site cultivates wood-based perennial and seasonal intercrop commodities. We measured CO2 and CH4 emissions monthly from 2020 to 2023 using an LGR™ ultraportable gas analyzer in eight permanent chambers at each site, concurrently with measuring Groundwater level (GWL). Our finding shows that CO2 emissions from heterotrophic soil respiration (Rh) in the intercropping site was nearly five times higher, with an annual average of 19.66 ± 0.62 Mg CO2 ha−21yr−1, compared to in the non-intercropping system, with a yearly average of 6.94 ± 1.55 Mg CO2 ha−1yr−1. The CO2 emissions from Rh accounted for 60-80% of CO2 emissions from total soil respiration (Rs). Similarly, CH4 emissions were higher in the intercropping site, with an annual average of 4.59 ± 2.52 kg CH4 ha−1yr−1 compared to 2.53 ± 0. 76 kg CH4 ha−1yr−1 in the non-intercropping site. Overall, soil-based global warming potential (GWP100) from the intercropping system is nearly three times higher (19.78 ± 0.57 Mg CO2-eq ha−1yr−1) than the non-intercropping system (7.00 ± 1.53 Mg CO2-eq ha−1yr−1). The study found that agroforestry with an intercropping system had a higher net soil CO2-eq emission than agroforestry without intercropping and may not achieve net soil zero carbon emissions. However, the non-intercropping site may achieve net soil zero carbon emission if wood-based perennial vegetation continues to grow, resembling the secondary peat swamp forest.
Growth and Yield of Corn Varieties on Flooded Burning Peat Soils
Authors: Rahayuningsih S E A , Zubaidah S , Kresnatita S , Maulana M D
Published: December 2024

The purpose of this study is to investigate effect of flooding on the growth and yield of a number of different types of corn grown in peat soil that has been burned. During the four-leaf phase, which lasts ten days, four different varieties of maize plants, namely BISI 2, BIMA 5, JH37, and NASA 29, were impacted by water. The level of the flooding was five centimeters. Starting in December 2020 and continuing until March 2021, the investigation was carried out at the experimental sites, which is part of the Department of Agricultural Cultivation, Faculty of Agriculture, Palangka Raya University. The research was conducted using a combination of three replications and a factorial randomized block design. The types of maize, specifically BISI 2, BIMA 5, JH37, and NASA 29, were flooded in their respective amounts, and a control does not show any signs of stagnation. Except for the quantity of leaves, there was no interaction between flooding and variety and it was not significant. There is a decrease in the number of leaves, stem diameter, plant dry weight, and maize kernel weight per plant when the plant is subjected to flooding stress.
Wild Edible Mushroom from Central Kalimantan and Its Potential for Other Benefits
Authors: Nion Y A , Djaya A A , Kamillah  , Agnestisia R , Mashabhi S , Nion K A
Published: December 2024

All cities and districts in the province of Central Kalimantan, Indonesia, have wild edible mushrooms. The research was conducted for a year (April 2023-April 2024). Twenty kinds of wild edible mushrooms were found in this study, with species names: Auricularia sp., Campanella buettneri, Calostoma insigne, Cookeina sulcipes, Favolaschia pustulosa, Hygrocybe conica, H. chloropana, Inocybe sp., Termitomyces sp, Lentinus sp., L. tigrinus, Oudemansiella sp., Phallus indusiatus, Pleurotus sp., P. ostreatus, Schizophillum commune, Tremella fuciformis, and V. volvaceae. The predominant genus are Pleurotus, Auricularia, Schizophyllum, Lentinus, and Volvariella. In addition, four species were growing on the ground, while the other remains were found on rotting plant stems in peat and non-peat forest areas. The potential nutritional and medicinal value of wild edible mushrooms, their benefits for health, and their applications in various industrial processes—such as wastewater treatment, bio-bleaching, detergent manufacture, dye degradation, juice clarification, biofuel production, and increased oil recovery—need to be optimized.
The Role Antagonistic Fungus of Solanum lasiocarpum Rhizophere to Control Chili Seed Borne Pathogen In Vitro
Authors: Mulyani R B , Djaya A A , Silitonga I L , Supriati L , Padriyani  , Melhanah
Published: December 2024

Colletotrichum gloeosporioides is a pathogen that can be carried by chili seeds. Control usually uses synthetic fungicides, but this can have negative impacts on the environment, human health and resistance to pathogenic fungi. A more environmentally friendly and safe control alternative is to use a biofungicide made from antagonistic fungi isolated from the rhizosphere of Terong Asam (Solanum lapiocarpum Dunal). The research was carried out in vitro using dual culture method, namely testing the pathogen C. gloeosporioides against the antagonistic fungi Trichoderma hamatum, T. harzianum, T. asperellum, Aspergillus niger, A. flavus, A. terreus, and Penicillium sp. the rhizosphere of Terong Asam. The results showed that all fungi obtained could inhibit the growth of the C. gloeosporioides seven days after isolation with different percentages of inhibition. High category of antagonistic activity has in Penicillium sp. (68.53%), T. asperellum (67.77%), T. hamatum and T. harzianum (66.27%) each, while other species showed low antagonist activity, namely A. flavus (40.63%), A. niger (33.58%), and A. terreus (28.70%). The difference of the inhibitory power is determined by the activity of antagonistic fungal mechanisms controlling pathogens, namely competition for growth sites and nutrients, antibiosis compounds produced and mycoparasitism. Antagonistic fungi that have high potential activity are used as biofungicides seed treatment to control C. gloeosporioides which infects seeds.
Current Insight: Habitat mosaic and landscape ecological services mapping based on local community knowledge in Karuing Village, Katingan Regency, Central Kalimantan
Authors: Pitoyo D , Adam C , Segah H , Surjanto D , Simon O , Anshori M
Published: December 2024

Habitat mosaic is an ecological phenomenon in which different habitats are found close together in varying patch sizes. This phenomenon is caused by environmental heterogeneity and disturbance events, both natural and anthropogenic. This anthropogenic disturbance cannot be separated from the existence of local communities that utilize its ecological services for their survival. Karuing Village is a village on the banks of the Katingan River in Katingan Regency, Central Kalimantan. The village landscape is surrounded by rivers and streams as well as forest ecosystems. The people of Karuing village have lived by utilizing ecological services for many years, especially aquatic resources from fishing. As time goes by, climate change occurs, causing shifts in the habitat mosaic and allowing new habitat patches to form. This research aims to map the habitat mosaic based on local knowledge of the community in Karuing Village, Katingan Regency, Central Kalimantan. In addition, this research also explores its potential as an ecological service that can be utilized by local communities. The results of this study provide the latest insight into the habitat mosaic and its ecological services in Karuing Village, Katingan Regency, Central Kalimantan, as a basis for conservation management plans and recommendations.
Measurement of Biomass and Carbon Emissions in Secondary Forest in Central Kalimantan, Indonesia
Authors: Yosep  , Salampak  , Yulianti N , Nasir D , Darung U
Published: December 2024

The aim of this research is to calculate carbon biomass above the surface in the form of vegetation and litter and calculate carbon emissions below the surface of secondary peat forests in the form of carbon emissions and roots. Field research was conducted in Tumbang Nusa Village, Jabiren District, Pulang Pisau Regency, Taruna Village, Sebangau District, Kalampangan, Palangka Raya City and in Hampangen, Katingan Hilir Regency, Central Kalimantan. Based on the analysis results, the highest average CO2 emissions in the treatment close to trees with root cutting (NT-T) was 423.30 ± 151.06 mg CO2 m−2 hours−1, with an average water surface height of 18.85 cm. while the lowest emissions in the treatment far from the tree were root cutting (FT-T) was 286.32 ± 107.97 mg CO2 m−2 hours−1 with an average water surface height of 20.05 cm. The highest CH4 emissions in the treatment far from the tree without root cutting (FT-U) were 1,246.00 ± 1,192.28 μg CH4 m−2 hours−1 with an average water surface height of 19.99 cm while the lowest emissions were in remote treatment with trees with root cutting (FT-T) was 893.69 ± 586.18 μg CH4 m−2 hours−1 with an average water surface height of 20.05 cm. Carbon reserves in secondary swamp forests amount to 82,115 tons/ha.
Consortium of Biological Agencies Trichoderma sp. and Mycorrhiza to Control Basal Stem Rot (Ganoderma sp.) on Oil Palm Seeds in Peat Soil Medi
Authors: Mulyani R B , Supriati L , Djaya A A , Nion Y A , Sihombing N H , Wardhana V W
Published: December 2024

Ganoderma is one of the diseases that attack the basal stem rot which is an important disease, especially in oil palm plantations that have undergone replanting. In Indonesia, the disease has attacked oil palm plantations in North Sumatra, Riau and Lampung with attack rates reaching 20-30%. This study aims to determine the ability of the consortium of biological agents Trichoderma sp. together with mycorrhiza in suppressing Ganoderma sp. infection on the roots of oil palm seedlings. This study used a completely randomized design (CRD) single factor 6 treatments with 3 replications. The research was carried out in the experimental farm and laboratory of the Department of Agronomy, Faculty of Agriculture, University of Palangka Raya from October 2018 to February 2019. The results showed that the consortium of T. harzianum and T. viridae was able to suppress Ganoderma sp. infection on the roots of oil palm seedlings by 44.0%, and 39.9% in the consortium T. koningi, T. NHP1 and T. longibrachiatum. The consortium treatment of T. harzianum and T. viridae which was applied together with mycorrhiza was able to suppress infection of Ganoderma sp. of 42.3% and 42.0% for the consortium treatment of T. koningi, T.NHP1 and T. longibrachiatum which was applied together with mycorrhiza. While a single treatment of mycorrhiza was able to suppress Ganoderma sp. infection. on the roots of oil palm seedlings by 45.7%.