bluuebunny/crossref_metadata_2025 huggingface dataset:
Oxidative cleavage of ketoximes to ketones using photoexcited nitroarenes
Authors: Göttemann Lucas T. , Wiesler Stefan , Sarpong Richmond
Published: November 2023

The photoexcited nitroarene mediated oxidative cleavage of methoximes is presented. The utility of the reaction is shown in a broad substrate scope and its relevance is underlined in several complex late-stage examples.
Recent progress of organic fluorescent molecules for bioimaging applications: cancer-relevant biomarkers
Authors: Zhang Chun , Sun Yi-Tao , Gan Suya , Ren Aimin , Milaneh Slieman , Xiang Da-Jun , Wang Wen-Long
Published: November 2023

The work reports the progress of small-fluorescent molecules for bioimaging applications to cancer-relevant biomarkers H+, NO, H2S and reactive oxygen species (H2O2, HClO, O2˙−, 1O2 and ˙OH) over the past six years.
A Decoder Structure Guided CNN‐Transformer Network for face super‐resolution
Authors: Dou Rui , Li Jiawen , Wan Xujie , Chang Heyou , Zheng Hao , Gao Guangwei
Published: November 2023

Recent advances in deep convolutional neural networks have shown improved performance in face super‐resolution through joint training with other tasks such as face analysis and landmark prediction. However, these methods have certain limitations. One major limitation is the requirement for manual marking information on the dataset for multi‐task joint learning. This additional marking process increases the computational cost of the network model. Additionally, since prior information is often estimated from low‐quality faces, the obtained guidance information tends to be inaccurate. To address these challenges, a novel Decoder Structure Guided CNN‐Transformer Network (DCTNet) is introduced, which utilises the newly proposed Global‐Local Feature Extraction Unit (GLFEU) for effective embedding. Specifically, the proposed GLFEU is composed of an attention branch and a Transformer branch, to simultaneously restore global facial structure and local texture details. Additionally, a Multi‐Stage Feature Fusion Module is incorporated to fuse features from different network stages, further improving the quality of the restored face images. Compared with previous methods, DCTNet improves Peak Signal‐to‐Noise Ratio by 0.23 and 0.19 dB on the CelebA and Helen datasets, respectively. Experimental results demonstrate that the designed DCTNet offers a simple yet powerful solution to recover detailed facial structures from low‐quality images.
Gum Acacia Stabilized Ag-TiO2 and Ag-SiO2: Sustainable Nanocatalysts for Direct and Convenient Synthesis of 5-Substituted 1H-tetrazoles
Authors: Prakash Supriya , Sreedhar Bojja , Naidu N. V. S.
Published: November 2023

We describe the use of biocompatible gum acacia (GA)-assembled Ag-TiO2 and Ag-SiO2 nanostructures as effective heterogeneous catalysts for the synthesis of 5-substituted 1H-tetrazoles through the traditional [3+2] cycloaddition of aryl nitriles with sodium azides. Characterization of the prepared catalysts employing TEM, XPS, FE-SEM, FT-IR, XRD, and TGA-DTG reveals silver nanoparticles encapsulated in the GA matrix amidst modified nano titania or silica. A variety of structurally divergent aryl nitriles were converted into the corresponding tetrazoles in a short reaction time. Other advantages include low catalytic load, easy handling of catalyst, limited use of toxic reagents, and desirable conversion yields, making this protocol a viable and practical alternative for this cyclization. The catalysts can be easily recovered and reused over multiple cycles without significant loss of catalytic activity.
A prickly business—Edward Shelton, Henry Tryon and the mysterious pineapple disease
Authors: Ryley Malcolm J. , Drenth Andre
Published: November 2023

The earliest record of pineapple plants being grown around Sydney in the British colony of New South Wales was that of Governor King in 1803. However, the climate of a new northern settlement at Moreton Bay (later Brisbane) soon proved to be far more conducive to growing the fruit. Pineapples prospered for over 50 years around Brisbane until a mysterious disease appeared in the late 1890s. In April 1891, Professor Edward Shelton, an American who had been appointed as the Queensland government’s first Instructor in Agriculture, was the first scientist to inspect the affected crops and concluded that the disease was caused by a fungus. In the following year, Shelton, Henry Tryon (then assistant curator at the Queensland Museum) and others again inspected the diseased pineapple crops. Tryon described the symptoms in detail as well as spores which were composed of two rounded elements, each having a double contour (chlamydospores). There is no doubt that the disease was caused by the oomycete Phytophthora cinnamomi that was described decades later. In 1897, Shelton was passionate about agricultural education and was appointed as the first principal of the Gatton Agricultural College, but his disciplining of some students of the college led to his forced resignation just 18 months later.
WITHDRAWN: Determination of thermal properties of unsmooth Si-nanowires
Authors: Liu Shi-Xian , Barinov A. A. , Yin Fei , Khvesyuk V. I.
Published: November 2023

Notice of Withdrawal

This paper was withdrawn by IOP Publishing on 19/03/2024. This paper was published due to an error. The authors are free to publish this work elsewhere. IOP Publishing apologise for this error.
Stringy running vacuum model and current tensions in cosmology
Authors: Gómez-Valent Adrià , Mavromatos N E , Solà Peracaula Joan
Published: November 2023

We discuss the potential alleviation ofboththe Hubble and the growth of galactic structure data tensions observed in the current epoch of cosmology in the context of the so-called stringy running vacuum model (RVM) of cosmology. This is a gravitational field theory coupled to matter, which, at early eras, contains gravitational (Chern–Simons (CS) type) anomalies and torsion, arising from the fundamental degrees of freedom of the massless gravitational multiplet of an underlying microscopic string theory. The model leads to RVM type inflation without external inflatons, arising from the quartic powers of the Hubble parameter that characterize the vacuum energy density due to primordial-gravitational-wave-induced anomaly CS condensates, and dominate the inflationary era. In modern eras, of relevance to this work, the gravitational anomalies are cancelled by chiral matter, generated at the end of the RVM inflationary era, but cosmic radiation and other matter fields are still responsible for a RVM energy density with terms exhibiting a quadratic-power-of-Hubble-parameter dependence, but also products of the latter with logarithmicH-dependencies, arising from potential quantum-gravity and quantum-matter loop effects. In this work, such terms are examined phenomenologically from the point of view of the potential alleviation of the aforementioned current tensions in cosmology. Using standard information criteria, we find that these tensions can be substantially alleviated in a way consistent not only with the data, but also with the underlying microscopic theory predictions, associated with the primordial dynamical breaking of supergravity that characterize a pre-RVM-inflationary phase of the model.
Kinetic gases in static spherically symmetric modified dispersion relations
Authors: Hohmann Manuel
Published: November 2023

We study the dynamics of a collisionless kinetic gas in the most general static, spherically symmetric dispersion relation. For a static, spherically symmetric kinetic gas, we derive the most general solution to these dynamics, and find that any solution is given by a one-particle distribution function which depends on three variables. For two particular solutions, describing a shell of monoenergetic orbiting particles and a purely radial inflow, we calculate the particle density as a function of the radial coordinate. As a particular example, we study aκ-Poincaré modification of the Schwarzschild metric dispersion relation and derive its influence on the particle density. Our results provide a possible route towards quantum gravity phenomenology via the observation of matter dynamics in the vicinity of massive compact objects.
Quantitative parameter reconstruction from optical coherence tomographic data
Authors: Veselka Leopold , Elbau Peter , Mindrinos Leonidas , Krainz Lisa , Drexler Wolfgang
Published: November 2023

Quantitative tissue information, like the light scattering properties, is considered as a key player in the detection of cancerous cells in medical diagnosis. A promising method to obtain these data is optical coherence tomography (OCT). In this article, we will therefore discuss the refractive index reconstruction from OCT data, employing a Gaussian beam based forward model. We consider in particular samples with a layered structure, meaning that the refractive index as a function of depth is well approximated by a piecewise constant function. For the reconstruction, we present a layer-by-layer method where in every step the refractive index is obtained via a discretized least squares minimization. For an approximated form of the minimization problem, we present an existence and uniqueness result. The applicability of the proposed method is then verified by reconstructing refractive indices of layered media from both simulated and experimental OCT data.
Inversion of generalized Radon transforms acting on 3D vector and symmetric tensor fields
Authors: Svetov Ivan E , Polyakova Anna P
Published: November 2023

Currently, theory of the ray transforms of vector and tensor fields is well developed, but the generalized Radon transforms of such fields have not been fully studied. We consider the normal, longitudinal and mixed Radon transforms (with integration over planes) acting on three-dimensional vector and symmetric tensor fields. We prove that these operators are continuous. In case when values of all generalized Radon transforms are known, inversion formulas are derived for componentwise reconstruction of vector and symmetric m-tensor fields,

m
⩾
2

. Novel detailed decompositions of 3D vector and symmetric 2-tensor fields as a sum of pairwise orthogonal terms are obtained. For construction of each term in the sum only one function is required. With usage of these decompositions we have described the kernels and images of the generalized Radon transforms. In addition, we have obtained inversion formulas for each of the generalized Radon transforms acting on 3D vector and symmetric 2-tensor fields and have formulated theorems similar to the projection theorem for the Radon transform. For the cases

m
⩾
3

similar statements are formulated as hypotheses. In addition, we consider the weighted longitudinal Radon transforms of 3D vector fields. Formulas are obtained for reconstructing the potential part of a 3D vector field from the known values of the longitudinal Radon transforms and one weighted Radon transform. Finally, we discuss the problem of vector fields reconstruction in

R

n

,

n
⩾
4

.
Hysteresis and loss characteristics of Fe-based nanocrystalline alloys based on a novel variable-temperature dynamic Jiles–Atherton hysteresis model
Authors: Xu Xueping , Zhao Zhenkai , Ren Jianyi , Ma Danyue
Published: November 2023

The magnetic characteristics of Fe-based nanocrystalline alloys can be influenced by temperature. The conventional dynamic Jiles–Atherton (J-A) hysteresis model does not take into consideration the impact that temperature has on magnetic characteristics. A novel variable-temperature dynamic J-A hysteresis model is proposed in this paper to effectively address the issue. Firstly, the hysteresis loops of Fe-based nanocrystalline are measured at −50 °C–130 °C and DC state. The five parameters of the J-A hysteresis model are identified at various temperatures using the particle swarm optimization algorithm, and five parameters are fitted as functions of temperature. Subsequently, the five parameters as functions of temperature are introduced into the conventional dynamic J-A hysteresis model to construct a novel variable-temperature dynamic J-A hysteresis model, which can not only reflect the impact of temperature but also accurately calculate the losses. Finally, hysteresis loops and losses of Fe-based nanocrystalline alloy are simulated and calculated at different temperatures and frequencies by the variable-temperature dynamic J-A hysteresis model. Meanwhile, this paper also investigates the trends and percentages of hysteresis loss, excess loss as well as eddy current loss with frequency and temperature. Compared to the results of measured data, the maximum average error of the variable-temperature dynamic J-A hysteresis model is 5.83%.
Interpretation of ion cyclotron emission from sub-Alfvénic beam-injected ions heated plasmas soon after L-H mode transition in EAST
Authors: Liu Lunan , Zhang Xinjun , Ochoukov R , Zhang Wei , McClements K G , Dendy R O , Salewski M , Zhu Yubao , Qin Chengming , Moseev D , Bobkov V , Chapman-Oplopoiou B , Zalzali A
Published: November 2023

Ion cyclotron emission (ICE) at deuterium ion cyclotron harmonics, driven by sub-Alfvénic beam-injected deuterium ions, has been observed by the high-frequency B-dot probe in the EAST tokamak. The origin of ICE shifts from the plasma core to the plasma edge soon after an L-H mode transition, where the beam-injected deuterium ions have a relatively peak bump-on tail structure in the energy direction and a very intense pitch angle anisotropy. Based on the fast ion distribution function obtained from the TRANSP/NUBEAM code, together with a linear analysis theory of magnetoacoustic cyclotron instability (MCI), the growth rates of MCI could be calculated. It is shown that MCI, resulting in the generation of obliquely propagating fast Alfvén waves at deuterium ion cyclotron harmonics, can occur under such conditions. And the temporal evolution of the MCI growth rate closely follows that of the observed ICE amplitude in the EAST.
Particle-in-cell simulations of high frequency capacitively coupled plasmas including spatially localised inductive-like heating
Authors: Osca Engelbrecht M , Ridgers C P , Dedrick J , Boswell R
Published: November 2023

High frequency (HF) capacitively coupled plasmas (CCPs) are ubiquitous, having several industrial applications, especially in the semiconductor industry. Inductive heating effects within these plasmas play an important role and therefore understanding them is key to improve industrial applications. For this purpose kinetic research, using particle-in-cell (PIC) codes, offers significant opportunity to study, and improve, industrial plasma processes that operate at the atomic level. However, PIC codes commonly used for CCPs are electrostatic and thus cannot be used to simulate electromagnetically induced currents. Therefore we have developed EPOCH-LTP, a 1D PIC code with a current heating model, that enables the simulation of inductive heating effects in HF CCPs. First simulation results, from an HF CCP (60 MHz) operated at 1 mTorr of argon, show that inductive currents couple most of their power to the electrons at the interface between the bulk plasma and the sheath. Furthermore, the simulation of a dual-frequency CCP, where a HF inductive current and a low-frequency (LF) voltage waveform at 400 kHz are applied, have shown a synergy between the HF and LF waveforms that increase the inductive heating rate.
The effect of organic clay on the properties of TPI/NR composite materials
Authors: Zhang Tao , Liang Yurong , Jia Yuhui , Shen Ruibing , Wang Long
Published: November 2023

TPI shape memory materials’ low flexibility and poor mechanical properties currently limit their use in a broader range of applications. Most scholars use high performance fillers to improve their mechanical properties. However, the cost of high-performance fillers is high. Therefore, the introduction of flexible natural rubber (NR) and low-cost organic clay (OC) into the trans-1,4-polyisoprene (TPI) matrix as the reinforcing phase. A new shape memory polymer— TPI/NR/OC, was prepared by mechanical melt blending.The effect of the changes of filler content on the thermodynamic properties of the composite materials were revealed by series of tests. The results showed that OC formed a homogeneous intercalation structure with the composite matrix, and OC promoted the crystallization of TPI, and part of OC was able to form physical entanglements with the molecular chains of the composites, which led to the improvement of mechanical and shape memory properties. The tensile strength of the composite at an OC dosage of 3.6phr was 19.9 MPa, with a shape fixity ratio of 97.9% and a shape recovery ratio of 96.8%. The relevant findings of this research may provide valuable design references for more areas of application of shape memory composites.
Scaling laws of two-dimensional incompressible turbulent transport
Authors: Palade D I , Pomârjanschi L M , Ghiţă M
Published: November 2023

The diffusive transport in two-dimensional incompressible turbulent fields is investigated with the aid of high-quality direct numerical simulations. Three classes of turbulence spectra that are able to capture both short and long-range time-space correlations and oscillating features are employed. We report novel scaling laws that depart from the γ = 7/10 paradigm of percolative exponents and are dependent on the features of turbulence. A simple relation between diffusion in the percolative and frozen regimes is found. The importance of discerning between differential and integral characteristic scales is emphasized.
Chaos and multistability in Josephson junction spurred by a Wien bridge oscillator: microcontroller implementation, chaotic and coexisting attractors controls
Authors: Godonou Daniel Maoussi , Sriram Balakrishnan , Ngongiah Isidore Komofor , Ainamon Cyrille , Rajagopal Karthikeyan
Published: November 2023

This paper explores the dynamics, microcontroller realization, chaotic, and coexisting attractors controls in the Josephson junction (JJ) spurred by the Wien bridge oscillator (WBO). The JJ spurred by WBO (JJSWBO) is designed by coupling through a gain a resistive-capacitive shunted JJ (RCSJJ) circuit to a WBO. The JJSWBO exhibits bistable periodic, monostable chaotic, and coexisting attractors as well as period-doubling bifurcation to chaos. A microcontroller implementation of JJSWBO is used to establish the dynamical behaviors spotted in JJSWBO during the numerical simulations. Moreover, two configured single controllers are engrossed to subdue the chaotic and coexisting behavior in JJSWBO. Lastly, thanks to the linear augmentation method, the coexisting attractors of JJSWBO are controlled to the desired trajectory.
Non-monotonic electromechanical deformation of dielectric elastomer actuators with different surface densities of carbon nanotubes
Authors: Zhang Fan , Zhang Junshi , Liu Lei , Zhu Jihong , Zhang Weihong
Published: November 2023

This paper investigates the influence of CNTs (carbon nanotubes) surface density on the electromechanical actuation of dielectric elastomer (DE) actuators. A filter transfer technique is utilized to deposit CNTs electrodes on VHB (Very-High-Bond) 4905 elastomers with different surface densities. The electromechanical characteristics of VHB 4905 elastomers with different surface densities of CNTs electrodes are evaluated experimentally. Theoretical models are simultaneously established to analyze with experimental measurements. It is found that increasing the CNTs surface density may alter the dielectric constant and modulus of DE actuators which results in a non-monotonic varying behavior of the electromechanical deformation under DC voltages. Furthermore, the stability and repeatability of the CNTs electrodes under AC voltage are verified by conducting additional experiments under different frequencies. This research can be used to determine the CNTs surface density to optimize the electromechanical actuation of DE actuators.
Numerical solutions of linear time-fractional advection-diffusion equations with modified Mittag-Leffler operator in a bounded domain
Authors: Odibat Zaid
Published: November 2023

Fractional advection-diffusion equations have demonstrated to be a powerful tool in modeling complex anomalous diffusion in applied science. In this paper, we studied novel linear time-fractional advection-diffusion equations associated with an extension of Mittag-Leffler fractional derivative operator. A useful feature of the used extension is to address the limitations of the Mittag-Leffler fractional derivative model. We, mainly, proposed a numerical approach to provide approximate solutions to linear time-fractional advection-diffusion equations with the studied extended fractional derivative operator. The suggested approach is based on discretizing the studied models with respect to spatio-temporal domain using uniform meshes. A new type of solutions for the studied models was generated numerically using the proposed approach. Besides, a comparative study was conducted to verify the accuracy and feasibility of the proposed approach.
Impact of intensity error on temperature estimation in laser-induced breakdown spectroscopy: a numerical study
Authors: John Lekha Mary , Anoop K K
Published: November 2023

Laser-induced breakdown spectroscopy (LIBS) is a cutting-edge technique for the compositional analysis of multi-element materials. Under standard circumstances for laser-induced plasma (T
e = 1 eV and N
e = 1016 cm−3), we simulated the emission spectrum of a binary alloy (with 70 wt.% Cu–30 wt.% Al). We used the Saha ionization equilibrium formulas to calculate the population of neutral and ionized species of each constituent element, and the Boltzmann distribution to estimate the intensities of emission lines with radiative transition probabilities. The Stark broadening equation is then used to determine the line broadening, yielding a Lorentzian profile for each line. The sum of line emissions of all constituent species will approximate the alloy’s LIBS spectra in an assumption of ideal analytical plasma. Then, we generated random errors in the intensities of spectral lines ranging from 5% to 35%. To investigate temperature estimation accuracy, we utilized three well-established approaches: the Boltzmann plot (BP) method, the Saha–Boltzmann plot (SBP) method, and the Multi-elemental SBP (MESBP) method. As intensity error increases from 5% to 35%, the estimated temperature in the BP method deviates from 0.25% to 18.3%. Whereas the intensity error is almost unaffected using the SBP method and the MESBP method. The temperature deviation is less than 2% in both situations. This study is relevant to calibration-free LIBS, in which the exact temperature determination is crucial for the abundance estimation of trace, major, and minor elements.
Development of high-performance long-pulse discharge in KSTAR
Authors: Kim Hyun-Seok , Jeon YoungMu , Han Hyunsun , Kim Kimin , Kim KwangPyo , Kim Heungsu , Rhee Tongnyeol , Kim Juhyung , Kim Junghee , Seo Dongcheol , Bang Eunnam , Ahn Hee-Jae , Ahn Hyun-Sik , Hong Jaesic , Jeong Jinhyun , Kong Jongdae , Kwak Jong-Gu , Jin Jongkook , Bak Jungyo , Park Kaprai , Lee Kyu-Dong , Joung Mi , Kwag Sang Woo , Hahn Sang-Hee , Kim SangKyeun , Yoon Si-Woo , Wang Sonjong , Kim Woong Chae , Kim Young-Ok ,   KSTAR Teams
Published: November 2023

High-performance long-pulse plasma operation is essential for producing economically viable fusion energy in tokamak devices. To achieve such discharges in KSTAR, firstly, the rapid increase in the temperature of plasma-facing components was mitigated. The temperature increase of the poloidal limiter, especially, was associated with beam-driven fast ion orbit loss and the discrepancy of the equilibrium reconstructed with heated magnetic probes of signal drift. The fast ions lost to the poloidal limiter were reduced by optimizing the plasma shape and the composition of neutral beam injection (NBI). This nonlinear signal drift was successfully reduced by a new thermal shielding protector on the magnetic probes. Secondly, a lower loop voltage approach was implemented to reduce a poloidal flux consumption rate. A plasma current of 400 kA and a line-averaged electron density of ∼2.0 × 1019 m−3 were chosen by considering the L–H power threshold, fast ion orbit loss, and beam shine-through power loss for low loop voltage in KSTAR. In addition, the application of electron cyclotron heating also helped maintain the plasma with low loop voltage (∼25 mV) by enhancing the NBI-driven current and achieving a high poloidal beta (β
P) state. KSTAR has achieved a long pulse (∼90 s) operation with the high performance of β
P ⩽ 2.7, thermal energy confinement enhancement factor (H98y2) ∼ 1.1, and fraction of non-inductive current (f
NI) ⩽ 0.96. Still, gradual degradation of the plasma performance has been observed over time in the discharges. In one of the long-pulse discharges, β
P reduced by ∼18% over the time of ∼8τ
R (current relaxation time, τ
R ∼ 5 s) and ∼1067τ
E,th (thermal energy confinement time, τ
E,th ∼ 45 ms). The degradation may be closely associated with weak, yet growing, and persistent toroidal Alfvén eigenmodes and their effect on fast ion confinement.
Development and analysis of whispering gallery mode model for refractive index sensing
Authors: Batumalay M. , Zain H.A , Rahim H.R.A. , Harun S. W.
Published: November 2023

A refractive index sensor based on a whispering gallery mode resonator is numerically investigated in this paper. Whispering gallery mode resonators confine light and can be used in sensing applications, and this work presents the model built using COMSOL software to analyze their sensing performance. This work has investigated the WGM resonators’ response to refractive index changes numerically using 2D models in the refractive index ranges 1.000 and 1.333. The resonator showed a sensitivity of 167 nm/RIU in the refractive index range of 1.3331.4 and a sensitivity of 95 nm/RIU in the refractive index range of 1.000-1.010. The sensing resonator has potential applications for biological and chemical analytes.
Quantum Properties in Nonlinear Coupler with Raman Process.
Authors: Hanapi Mohd Syafiq M. , Ibrahim Abdel-Baset M. A.
Published: November 2023

In this work, we have examined the generation of squeezed states of light in a two-waveguide coupler in which Raman processes are active in one waveguide. Both waveguides are mutually linearly interacting through the field’s evanescent waves. We looked at a few interesting cases in which the system generated single mode squeezed states due to spontaneous and stimulated Raman processes. Under specific combinations of design parameters and phase mismatching conditions, squeezed states may take the form of collapses and revivals, or the second quadrature of the optical mode may oscillate completely below the short-noise limit of a coherent state.
Sensitivity Performance of Optical Waveguide Sensors with Different Shapes of Cladding Layer for Microplastics Detection
Authors: Hanafi A I M , Saris N N H , Idrus S M , Hamzah A
Published: November 2023

With microplastics pollution becoming a global concern, there comes a need for sensors to attain an optimal level of sensitivity to detect microplastics in water. This work investigated the effects of cladding layer shapes on the sensitivity performance of an optical waveguide sensor for microplastics detection in water. In this research, three different cladding shapes—C-shaped fiber, D-shaped fiber, and rectangular waveguide with circular core—were simulated by using Wave Optics Module-COMSOL Multiphysics® software. The results indicated that the C-shaped fiber exhibited significantly higher sensitivity, with a sensitivity value of 1.070x10−3 compared to the D-shaped fiber and rectangular waveguide with 3.845x10−4 and 3.842x10−4, respectively. The sensitivities of the D-shaped fiber and rectangular waveguide were relatively similar and did not exhibit any significant difference. The higher sensitivity of the C-shaped fiber is attributed to its larger exposed core area to the analyte, resulting in higher interaction of the evanescent wave with the analyte. However, fabricating the C-shaped fiber is more challenging compared to the other two shapes. This research highlights the significance of cladding shapes in optical waveguide sensor sensitivities and provides design optimization insights for microplastics detection in water.
Centralized Monitoring for Huge FTTH Network using Code Grating
Authors: Ahmad Norhidayah , Rahman MS , Ahmad Abas AH
Published: November 2023

The Covid-19 has impacted the demand in broadband communication specifically in Fiber to the Home (FTTH). The increase in the demand caused the increase in the number of users in Triple play service during the Movement Control Order (MCO) period. Consequently, the high volume of user has slowed down the internet speed and connectivity. In addition, there is no effective monitoring system to monitor the network health from user end. This study was conducted to design a PON Fiber-to-the-Home (FTTH) network which can serve thousands of users by increasing the capacity of the network and at the same time the network operator will be able to monitor any faulty branch(s) at the user end. By upgrading the new component in PON FTTH such as SOA, AWG and Demultiplexer, the network is able to support up to 30 000 users and also able to monitor fault user branches in FTTH network by using code FBG.
The effect of temperature to the reflected signal of PMMA FBG in FTTH network
Authors: Ahmad Abas A H , Rahman M S , Ahmad Norhidayah
Published: November 2023

The need for an early detection of disaster has grown vital because of the rise in natural disaster events occurred in Malaysia recently, such as fire, landslides, and floods. Thus, an early warning system could somehow reduce the seriousness of disaster. Due to this, Polymer Optical Fiber (POF) has garnered a lot of interest, because of its promising features especially for becoming a sensing device. This paper study the effectiveness of polymer FBG sensor in Fiber-To-The Home (FTTH) network. The simulation was done using OptiSystem7.0 software. The changes of power(dBm) due to the temperature changes was tabulated. PMMA has shown a significant change in power with averagely 1.123 dBm drop for every 10°C increase of temperature. This indicates that PMMA have promising characteristics to become the main material for fabrication of FBG sensor.
On the basic mechanism of grain growth: the role of texture on grain boundary migration rate
Authors: Abbruzzese G C
Published: November 2023

In this paper we will review some of the many achievements of Statistical Theory of Grain Growth (which is 40 years old, this year!), based on the classic law of grain growth. For instance, we will show that grain growth in presence of texture (which is the usual feature in a real microstructure) is not exclusively depending on the curvature of the grain boundary, as in this case the effect of curvature at the vertexes (in 2-D case) contributes as well (which, depending on the texture pattern, sometimes may be more relevant than curvature along the boundary). Such phenomenon requires a reformulation of Von Neuman’s equation in 2-D by involving, beside the different boundary mobilities, the different energies of the “third” grain boundary, which is pulling the vertex and inducing an extra curvature which is not balanced along the grain perimeter (for simplicity’s sake we are referring to a 2-D case, but the analysis can also be done in 3-D). We can then observe that boundary movement is not only depending on a couple of grains in contact (with the boundary curvature acting like in a bicrystal) but also includes the network of “third” grains operating at the vertexes. The overall consequence is that the growth kinetics and the grain size distribution shape are unique and variable for each texture component which contradicts classic growth laws as well as the expected results for the whole grain size distribution.
Understanding the static recrystallization of Ni-Mo alloyed steels for rolling optimization in high strength thick plates
Authors: Miguel L San , Isasti N , Detemple E , Mohrbacher H , Uranga P
Published: November 2023

The development of high strength/high toughness steel grades for thick plates requires an optimum combination of alloy design and processing conditions. In this contribution, the effect that Molybdenum and Nickel have on the static recrystallization kinetics during roughing passes is analyzed. High alloying additions, especially in the case of Mo, imply intense solute drag delay for static recrystallization. This mechanism, added to the low reductions typically applied during roughing of thick plates, reduces the possibility for a complete recrystallization between passes and limit austenite conditioning and grain size refinement. Under these circumstances, the understanding and modelling of static recrystallization becomes relevant. Hot torsion tests were carried out and the effect of alloying elements on the recrystallization kinetics and recrystallized grain size was quantified in four different steel grades with several Molybdenum (0.25-0.5%) and Nickel combinations (0-0.5%). Finally, the softening behavior and microstructural evolution during multipass roughing rolling simulations was compared with MicroSim® model predictions, showing a reasonable agreement with experimental results.
Heterogeneous microstructure design by pre-manipulating ferrite recrystallization in a cold rolled medium Mn steel
Authors: Zheng Qinyuan , Lu Yi , Hu Baojia , Zheng Chengwu , Li Dianzhong
Published: November 2023

The medium Mn steel (MMS), which is regarded as the most representative candidate of the third generation advanced high strength steels, has received widely attention during the last several decades with respect to the exceptional advantage of low cost and excellent strength-ductility properties. In this study, a microstructural strategy of developing heterogeneous microstructures in a cold rolled MMS is presented. By pre-manipulating occurrence of the ferrite recrystallization, both the lamellar-shaped and granular-shaped ultra-fine retained austenite can be obtained after the two-step intercritical annealing process. Various amounts of recrystallized ferrite and difform martensite can be obtained by adjusting the pre-annealing temperature, which can effectively contribute to producing the two types of heterogeneous retained austenite, i.e., lamellar and granular in the following annealing process. The heterogeneous-structured retained austenite enables an excellent strength–ductility combination and reduced Lüders strain in the cold-rolled MMS.
Influence of roll-bending deformation on microstructure and texture in an Al-Li alloy with different extrusion aspect ratio
Authors: Hou X K , Qi Y T , Li B L , Yin J M , Qi P , Wen S P , Wei W , Yao C G , Hu Z G , Nie Z R
Published: November 2023

The purpose of this investigation is to study the effect of roll bending deformation on the microstructure and texture in an Al-Li alloy with different extrusion aspect ratios. The results indicated that the substructure of most extruded fiber grains is not completely eliminated on the ND-ED section at position B with a low extrusion aspect ratio. However, the texture type of the ND-TD section changes from a single <114> texture to an adjacent <112> texture after roll-bending deformation, and the texture intensity decreases from 8.3 to 6.1. With the increase of the extrusion aspect ratio, the effect of roll-bending deformation on the microstructure began to be obvious, especially at position C. A large number of elongated recrystallized grains along the ED direction were transformed into approximately equiaxed grains on ND-ED section after the roll-bending deformation. There were also a small number of approximately equiaxed cell structures. The relative frequency of the low-angle grain boundary rose slightly from 42.1% to 46.7%. The single <313> texture moved to the adjacent <112> texture, and the texture strength increased from 4.8 to 6.3.
Self-Annealing Phenomena in the Cold-Rolled and Cryo-Rolled Copper Alloys: A Review
Authors: Gupta Aman , Choi Shi-Hoon
Published: November 2023

Severely deformed copper (Cu) alloys showed the self-annealing behaviour when exposed at room temperature (RT) for a prolonged time. This phenomenon results in the evolution of self-annealed grains, dislocations annihilations, and a decrease in the strength. The present review work addresses the evolution of self-annealed microstructures in room-temperature-rolled (RTR) and cryogenic-rolled (CR) Cu alloys, including various grades of Cu alloys such as ETP Cu, Cu-Fe-P, Cu-Sn-Mg alloys that were studied in terms of RT softening. Static recrystallization (SRX) at room temperature (RT) was observed in the highly deformed RTR and CR Cu alloy samples. Both discontinuous SRX (DSRX) and continuous SRX (CSRX) were responsible for the nucleation of small grains at RT. Particle-stimulated nucleation (PSN) also contributed to small-grain formations around Cu2O particles in ETP Cu. However, no PSN was reported for the Cu-Fe-P and Cu-Sn-Mg alloys. The formation of strain localizations (SLs) and shear bands (SBs) was observed in the deformed Cu alloys; these sites were preferred for grain nucleation during RT recrystallization.
Tailoring mechanical properties of Fe-32Mn-0.6C steel via deformation, dynamic recovery and recrystallization
Authors: Xiong J C , Liu E Z , Kong L , Qi X D , Yang H K , Zhang X D , Wang Y H
Published: November 2023

The microstructures and mechanical properties of Fe-32Mn-0.6C steel after deformation, dynamic recovery and recrystallization were investigated. Dynamic recovery occurred during rolling at 800°C, and fined subgrains formed at deformation introduced lamellar boundaries. During tensile deformation, a large amount of deformation twins is activated, leading to a high work-hardening. Compared to the cold-rolled and coarse-grained recrystallized samples, the 800°C rolled sample shows an improved combination of strength and ductility at both room temperature (RT) and liquid nitrogen temperature (LNT). Specifically, the yield strength and uniform elongation are 702 MPa and 61%, respectively, at RT and are 1013 MPa and 48%, respectively, at LNT.
Study on dynamic recrystallization of ultra-high strength 22MnB5 steel during hot rolling
Authors: Long M J , Zhang H H , Yang X H , Guo W , Ai S Y , Chen D F
Published: November 2023

The effect of deformation temperature and strain rate on the recrystallization behavior of ultra-high strength hot formed 22MnB5 steel was systematically studied by isothermal compression experiments, and the microstructure was characterized and analyzed. The results show that the peak stress and peak strain of 22MnB5 steel decrease with increasing deformation temperature and increase with increasing strain rate. The dynamic recrystallization of 22MnB5 steel is more sensitive to temperature and less affected by strain rate. The recrystallization behavior is significant during isothermal deformation above 1323 K. Based on the hyperbolic sinusoidal constitutive equation, the accurate prediction model of dynamic recrystallization grain size and a dynamic recrystallization critical strain model for 22MnB5 steel were established. The relationship between recrystallization austenite grain size and deformation temperature and deformation amount was obtained as follows: d=4.1×103[ε·exp(350.38/RT)]. The critical strains of complete recrystallization and complete non-crystallization at each deformation temperatures were determined by the critical strain model, which can provide a basis for the optimization design of rolling process parameters.
Dynamic recrystallization of Ti-6Al-4V alloy promoted by laser shock peening
Authors: Zhang L , Ouyang W T , Du Y X , Guo C H , Zhang W W
Published: November 2023

In this study, the influences of different numbers of passes of laser shock peening (LSP) on the surface microstructures of Ti-6Al-4V alloy were investigated. Especially, the microstructural evolution of the As-received (AR) sample and LSP treated samples was observed by scanning electron microscope (SEM) and electron backscatter diffraction (EBSD) observations. The results showed the grain size and the distribution of α, β phase have changed after the LSP process. After 1 LSP processing, the grain size is more uniform, the β phases were transformed from scattered and laminar characteristics to linear characteristics, while the α phases were parcelled by the β phases. After 2 LSP treatment, obvious grain refinement can be observed and the influence depth is deeper compared to the 1 LSP sample. After laser shock peeing processing, the material also has obvious dynamic recrystallization (DRX). Finally, the mechanism of microstructure evolution by LSP was revealed.
Σ3 grain boundary dynamics studied by atomistic spherical bicrystal modeling
Authors: Li R , Homer E R , Zhang Y , Jensen D Juul
Published: November 2023

In this study, we propose an atomistic spherical bicrystal model that employs the synthetic driving force method to investigate the dynamics of curved interfaces. The model allows tracking the migration and faceting of spherical grain boundaries. As a demonstration case, a simulation for a grain boundary with Σ3 misorientation is performed. A subsequent analysis of interface energy and stiffness is performed, whereby it is found that the dynamics of [111] and

[

1
¯

1
¯

2
]

segments in the Σ3 boundary plane fundamental zone follow energy and stiffness trends, while others, e.g., the

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0

1
¯

1
]

segment, do not.
The influence of cooling rate on microstructure and magnetic properties of cast Fe-6.5wt%Si steel
Authors: Zhang J , Liu K , Sun F , Liu R , Wu G , Wang M , Gu S , Zhu Z , Mao X
Published: November 2023

Fe-6.5wt%Si steel samples of different thicknesses (1 mm, 2 mm, and 5 mm) were prepared by arc-melting and suction-casting with sub-rapid solidification rates. The microstructures and magnetic properties of the samples were studied, and the effect of solidification rates were discussed. Results show that columnar crystals are generated with a <100> fiber texture after casting. Ordered phases B2 and D03 are inhibited by sub-rapid solidification, and such an effect is clear in the 1 mm thick sample with the largest cooling rate. With decreasing cooling rate, the grain size increases, with the mean values being 66.6±30.8 μm, 93.0±42.8 μm, and 149.7±66.8 μm, and the intensity of the <100> texture increases, with the values being 3.14 mrd, 3.56 mrd, and 5.85 mrd, respectively. The 5 mm thick sample with the lowest cooling rate exhibits the best magnetic properties (B8=1.30 T, B50=1.55 T, P1/50=2.19 W/kg, P1/400=37.85 W/kg).
Microstructural path modeling of primary recrystallization
Authors: Vandermeer R A , Jensen D Juul
Published: November 2023

While the classic KJMA model is frequently used to fit experimental recrystallization kinetics data, the fitted values in most cases are inconsistent with the observed microstructural evolution. In this paper, we review the much more powerful microstructural path modeling (MPM) methodology. A basic assumption in this next generation of recrystallization models is related to the spatial distribution of nucleation sites, which may be uniform in the mathematical sense, i.e. randomly distributed in the sample volume, or clustered either along lines or on planes. For example nuclei are often observed to be linearly aligned because they have formed along original grain boundaries or stringers of second phase particles in the deformed matrix. In this paper, we present a new MPM, which is extending the former idealized linear MPM, allowing the recrystallizing grains to grow with different speeds in different directions, thus becoming prolate spheroid shaped. Finally issues concerning experimental determination and analysis of growth rates, are discussed.
Modeling the hot deformation behavior of micro-alloyed steel in the single and two-phase fields
Authors: Sharifi S S , Buzolin R H , Bakhtiari S , Gontijo M , Sommitsch C , Poletti M C
Published: November 2023

Continuous casting is a well-established process to produce steel slabs. However, the surfaces of the slabs may crack during processing. The occurrence of cracks is related to different phenomena, i.e., ferrite formation, presence of precipitates, and microstructural modifications during manufacturing processing. In the present work, we developed a physically based mesoscale model to describe the plastic deformation of micro-alloyed steel in the single and two-phase fields, as well as the microstructure evolution. We implemented a dislocation density-based constitutive model to calculate the strain hardening and the stress softening produced by dynamic recovery using the Kocks-Mecking (KM) formalism for the austenite and ferrite. We coupled the KM model with the Johnson-Mehl-Avrami-Kolmogorov model to consider the dynamic recrystallization of the austenitic phase. The nucleation and growth of the recrystallized grains, driven by the stored energy, compete with the annihilation of dislocations due to dynamic recovery. In the two-phase domain, the iso-work condition for the load partition is implemented. We calculated the ferrite volume fraction by fitting the data obtained using JmatPro software. Moreover, an Arrhenius-type equation correlates the yield stress to the Zener-Hollomon parameter. We validated the model with isothermal uniaxial compression tests of microalloyed steel over the temperature range of 650 °C-1100 °C and strain rates of 10−2 s−1 and 10−3 s−1 using a Gleeble® 3800 thermomechanical simulator.
The effect of subgrain mobility on recrystallization kinetics: phase-field simulation study
Authors: Abramova O , Prahs A , Schneider D , Nestler B
Published: November 2023

The influence of grain boundary mobility on the recrystallization process (ReX) was investigated in this study using the phase-field approach. In accordance with the Read-Shockley equation, for the interfacial mobility as a function of the misorientation angle, the resulting microstructural evolution was studied. It was observed that the disappearance of low-angle grain boundaries (LAGBs) during the ReX process caused high-angle grain boundaries to move faster during the subsequent ReX stages. For materials with high stacking energy, such as aluminum, LAGBs were additionally found to play a significant role in the ReX process. The kinetics of the ReX process, coupled with grain growth, showed the typical behavior observed in fine-grained structures of pure aluminum.
Effect of boundary grooving on grain growth by Potts model simulations
Authors: Zöllner D , Pantleon W
Published: November 2023

Grain growth in thin films is a technologically important and scientifically fascinating topic: As the grain size influences many mechanical and optical properties of a material, any change in the grain structure and therewith in the grain size changes also the materials properties. There are many factors influencing coarsening of the microstructure such as grain boundary properties or the presence of particles; additionally the film thickness becomes rather important. It has been observed that when the grain size reaches the magnitude of the layer thickness, coarsening slows down and may even stagnate. For thin films, surface effects such as grain boundary grooving become important. In general, grooves are totally left out of implementations in the standard Potts model. In the current investigation, we introduce grain boundary grooves in the Potts model as physical entities. In the analysis, we show how the mere presence of such grooves reduces the driving force of grain boundary migration at the surface tremendously at any stage of coarsening.