bluuebunny/crossref_metadata_2025 huggingface dataset:
Demonstrating the electron blocking effect of AlGaN/GaN superlattice cladding layers in GaN-based laser diodes
Authors: Li Shukun , Lei Menglai , Lang Rui , Yu Guo , Chen Huanqing , Wen Peijun , Khan Muhammad Saddique Akbar , Meng Linghai , Zong Hua , Jiang Shengxiang , Hu Xiaodong
Published: May 2023

Electron leakage currents seriously limit the power conversion efficiencies (PCEs) of gallium nitride (GaN)-based laser diodes (LDs). To minimize the leakage currents, electron blocking layers are generally applied in the p-type region. However, few works have discussed the electron blocking effect of a p-cladding layer, which is found to be critical in suppressing the leakage currents of an LD. In this work, we compare the blocking performance of uniform AlGaN p-cladding layers and AlGaN/GaN superlattice (SL) p-cladding layers with the same average Al component respectively. Both light-emitting diodes (LEDs) and LDs with the same epitaxy structures are characterized by light–current (L–I) and current–voltage (I–V) measurements. The latest analytical model of leakage currents is applied to fit the L–I curves of LEDs, where smaller leakage coefficients are observed in the SL structures compared with the uniform-layer structures. Eighty LDs with varying ridge widths are studied by comparing the threshold current densities, slope efficiencies, and PCEs. The SL-based p-cladding layer shows statistically significant advantages over a uniform AlGaN layer. The blocking effects of both scattering- and bound-state electrons in SLs are investigated theoretically. Repetitive reflection and thermal relaxation are responsible for the blocking effect of scattering-state electrons. Simulation results indicate that the tunneling effect of bound-state electrons through a miniband mechanism is insignificant at a large injection level due to a negative differential conductivity by the Esaki–Tsu effect. We demonstrate a better electron blocking performance of p-cladding layers based on SLs than uniform AlGaN layers in GaN-based LDs.
Ligand field luminescence in the honeycomb Mott insulator α-RuCl3
Authors: Mandal Shoubhik , Banerjee Abhishek , Ganesan R , Kumar P S Anil
Published: May 2023

Novel electronic structure is central to Kitaev-like quantum spin liquid ground state in the van der Waals antiferromagnet α-RuCl3. In this octahedral low-spin

4

d
5

system, the rich bandstructure includes Mott–Hubbard insulating bandgap of ∼1.1 eV and ligand field induced gap of ∼2 eV. Though the bandgap is extensively reported in previous optical and photoemission studies, the latter gap is less understood. In this regard, we probed the ligand field-induced electronic structure of bulk α-RuCl3 single crystals via unpolarized photoluminescence (PL) spectroscopy under linearly polarized excitation in the visible region. We observed the broad principal PL peak at E
PL

≈

1.87 eV, close to the energy required for the optical transition across the ligand field splitting gap (∼2 eV). This gap (E
PL) monotonically increases with temperature, described by the thermal expansion of lattice parameters dominating the electron–phonon interaction in this Honeycomb Mott insulator. Moreover, we observed the multiplet structure of the PL spectra, which can be explained by parity-forbidden d–d transitions in the light of single ion ligand-field theory. We attribute the broad PL linewidths to strong vibronic coupling modeled by the Huang–Rhys parameter. Further we observed the signature of structural transitions, indicated by thermal hysteresis in normalized integrated PL intensity.
Electronic properties of EuO and Eu2O3: FP-LAPW and LCAO computations and Compton spectroscopy strategies
Authors: Meena Lekhraj , Meena Seema K , Ahuja Ushma , Heda N L , Ahuja B L
Published: May 2023

Spin projected energy bands and density of states (DOS) have been deduced using full potential linearized augmented plane wave (FP-LAPW) with density functional theory (DFT) to analyze the electronic properties of EuO and Eu2O3. Whereas the Mulliken population (MP) and Compton profiles (CPs) for both the compounds have been computed using linear combination of atomic orbitals (LCAO) with pure and hybrid DFT (WC1LYP) schemes. The MP analysis indicates EuO to be more covalent than Eu2O3. Our first ever CP measurements for Eu2O3 (using 20 Ci 137Cs Compton spectrometer) indicate DFT with generalized gradient approximation and WC1LYP as successful prescriptions for predicting the electronic properties of such rare-Earth oxides. In addition, equally normalized experimental CPs of Eu2O3 are compared with other rare-Earth oxides RE2O3 (RE = Nd, Sm, Er and Yb) to decide an overall trend of localisation of f-electrons. A metallic behaviour of Eu2O3 is observed on the basis of real-space analysis of experimental, LCAO and free electron theory based CPs of Eu2O3.
Morphology, structural properties, impedance spectroscopy, AC conductivity, and dielectric relaxation properties of boron subphthalocyanine chloride amorphous films
Authors: Darwish A A A , Qashou Saleem I , El-Zaidia E F M , El-Rahman K F Abd , Hamdalla Taymour A , Al-Ghamdi S A , Alsharari Abdulrhman M , Khasim Syed , Alzahrani Ahmed Obaid M , Yahia I S
Published: May 2023

Through the use of thermal evaporation, boron subphthalocyanine chloride (B-subPcCl) films were created. X-ray diffraction pattern reveals that the B-subPcCl is characterized by amorphous nature, while atomic force microscopy images show that the surface topography of B-subPcCl is composed of homogeneous elliptical nanoparticles with grain size and roughness of 90 and 70 nm, respectively. The impedance measurements of B-subPcCl film at the temperature ranges of 298–398 K were studied and were fitted to the analog of a Rp//CPE equivalent electrical circuit model. The relationship between AC conductivity and frequency at different temperatures demonstrated that the correlated barrier hopping (CBH) model dominates the transport charge mechanism between the closest sites. The DC conductivity parameters were calculated, and they were compared with the relative organic compounds. The dependence of the dielectric constant (ε
1) and the dielectric loss (ε
1) on frequency showed a significant decrease of ε
1 and ε
2 values as the frequency increased. At different temperatures, the variation of the imaginary modulus (M
2) of B-subPcCl with frequency showed a relaxation process with an activation energy of 0.066 eV.
Theoretical analysis of a mid-infrared Kerr frequency comb in a graphene-on-silicon micro-resonator
Authors: Chen Weicheng , He Qi , Guo Rongxiang , Wan Dian , Han Qun , Hu Haofeng , Wang Jiaqi , Zou Yi , Xiao Ting-Hui , Liu Tiegen , Cheng Zhenzhou
Published: May 2023

Mid-infrared (Mid-IR) Kerr frequency combs have great application potential in sensing and spectroscopy. To generate a Kerr frequency comb, a continuous-wave, wavelength-tunable, narrow-linewidth, low-noise laser is normally utilized to pump a high-nonlinearity micro-resonator to emit a large number of coherent and equally spaced modes. However, chip-based pump lasers in the mid-IR band, namely, quantum cascade lasers and interband cascade lasers, are usually challenging to develop with both high output powers and good wavelength tunability based on a single diode. To overcome the limitation, we theoretically study a mid-IR Kerr frequency comb generation technique based on a graphene-on-silicon micro-resonator by using a monochromatic mid-IR laser. The approach is based on the exploration of an electric-field-assisted resonance scanning technique and graphene-enhanced silicon Kerr nonlinearity. Our result shows that a soliton Kerr frequency comb with a spectral range of 3.23–5.26 μm, 3-dB bandwidth of ∼550 nm, and frequency spacing of 140 GHz could be generated under a pump wavelength of 4 μm. The study paves a promising way toward developing monolithically chip-integrated mid-IR Kerr frequency combs with cost efficiencies and ultrafast tuning speeds.
Dark matter axions in the early universe with a period of increasing temperature
Authors: Arias Paola , Bernal Nicolás , Osiński Jacek K. , Roszkowski Leszek
Published: May 2023

We consider the production of axion dark matter through the misalignment mechanism in the context of a nonstandard cosmological history involving early matter domination by a scalar field with a time-dependent decay rate. In cases where the temperature of the Universe experiences a temporary period of increase, Hubble friction can be restored in the evolution of the axion field, resulting in the possibility of up to three “crossings” of the axion mass and the Hubble expansion rate.
This has the effect of dynamically resetting the misalignment mechanism to a new initial state for a second distinct phase of oscillation.
The resultant axion mass required for the present dark matter relic density is never bigger than the standard-history window and can be smaller by more than three orders of magnitude, which can be probed by upcoming experiments such as ABRACADABRA, KLASH, ADMX, MADMAX, and ORGAN, targeting the axion-photon coupling. This highlights the possibility of exploring the cosmological history prior to Big Bang Nucleosynthesis through searches for axion dark matter beyond the standard window.
Searching for photon-ALPs mixing effects in AGN gamma-ray energy spectra
Authors: Yu Qixin , Horns Dieter
Published: May 2023

High energy gamma-rays propagating in external magnetic fields may convert into axion-like particles (ALPs). In this case, the observed gamma-ray spectra are modified
by the resulting energy-dependent conversion probability.
In this study, we use the energy spectra of 20 extra-galactic gamma-ray sources recorded during 10 years of Fermi-LAT observations.
We define a test statistics based upon the likelihood ratio to test the hypothesis for a spectral model without vs. a model
with photon-ALPs coupling. The conversion probability is calculated for fixed values of the mass and two-photon coupling of the pseudo-scalar
particle while the external magnetic field is characterized by the additional free parameters length scale s and average field strength B.
As a consistency check and in order to extend the analysis to include very high energy gamma-ray data, another test statistics is defined
with the χ2 method.
We find for 18 of the 20 sources a favorable fit, particularly for Markarian 421 and NGC 1275 a significant improvement, with the hypothesis of photon-ALPs coupling in likelihood analysis. The
test statistics of the sources are combined and the significance has been estimated 5.3σ (test statistics summed in local maxima of all sources) and 6.0σ (global maxima). The significance is estimated from dedicated simulations under the null hypotheses. The locally best-fitting values of B and s fall into the range that is
expected for large scale magnetic fields present in relevant astrophysical environments.
Testing gravity with gravitational wave friction and gravitational slip
Authors: Matos Isabela S. , Bellini Emilio , Calvão Maurício O. , Kunz Martin
Published: May 2023

Gravitational waves (GWs) emitted by binary sources are interesting signals for testing gravity on cosmological scales since they allow measurements of the luminosity distance. When followed by electromagnetic counterparts, in particular, they enable a reconstruction of the GW-distance-redshift relation. In the context of several modified gravity (MG) theories, even when requiring that the speed of propagation is equal to that of light, this GW distance differs from the standard electromagnetic luminosity distance due to the presence of a modified friction in the GW propagation. The very same source of this friction, which is the running of an effective Planck mass, also affects the scalar sector generating gravitational slip, i.e. a difference between the scalar potentials, an observable that can be inferred from large-scale structure (LSS) probes. In this work, we use a model within effective field theories for dark energy to exemplify precisely the fact that, at the linear perturbation level, parametrizing a single function is already enough to generate simultaneous deviations in the GW distance and the slip. By simulating multimessenger GW events that might be detected by the Einstein Telescope in the future, we compare the constraining power of the two observables on this single degree of freedom. We then combine forecasts of an Euclid-like survey with GW simulations, coming to the conclusion that, when using Planck data to better constrain the cosmological parameters, those future data on the scalar and tensor sectors are competitive to probe such deviations from General Relativity, with LSS giving stronger (but more model-dependent) results than GWs.
Astrophysical observables for regular black holes with sub-Planckian curvature*
Authors: Zeng Wei , Ling Yi , Jiang Qing-Quan
Published: May 2023

We investigate the photon sphere and marginally stable circular orbit of massive particles over the recently proposed regular black holes with sub-Planckian curvature and a Minkowskian core. We derive the effective potential for geodesic orbits and determine the radius of circular photon orbits, with an analysis of the stability of these orbits. We extend our analysis to the background of a compact massive object (CMO) without a horizon, whose mass is below the lowest bound for the formation of a black hole. For massive particles, marginally stable circular orbits become double-valued in the CMO phase. Through a comparison with Bardeen and Hayward black holes, we also find that the locations of the photon sphere and marginally stable circular orbit in the CMO phase with a Minkowskian core are evidently different from those in the CMO phase with a dS core, which potentially provides a way to distinguish between these two types of black holes by astronomical observation. Finally, we present the observational constraint on the deviation parameter for such regular black holes using observed data from the black hole M87*.
Cleaning Radio Frequency Interference in Pulsar-Folded Data Based on the Conditional Random Fields with an Adaptive Prior
Authors: Chen Xue , Han J. L. , Su W. Q. , Yang Z. L. , Zhou D. J.
Published: May 2023

Radio astronomy observations are frequently impacted by radio frequency interference (RFI). We propose a novel method, named 2σCRF, for cleaning RFI in the folded data of pulsar observations, utilizing a Bayesian-based model called conditional random fields (CRFs). This algorithm minimizes the “energy” of every pixel given an initial label. The standard deviations (i.e., rms values) of the folded pulsar data are utilized as pixels for all subintegrations and channels. Non-RFI data without obvious interference is treated as “background noise,” while RFI-affected data have different classes due to their exceptional rms values. This initial labeling can be automated and is adaptive to the actual data. The CRF algorithm optimizes the label category for each pixel of the image with the prior initial labels. We demonstrate the efficacy of the proposed method on pulsar folded data obtained from Five-hundred-meter Aperture Spherical radio Telescope observations. It can effectively recognize and tag various categories of RFIs, including broadband or narrowband, constant or instantaneous, and even weak RFIs that are unrecognizable in some pixels but picked out based on their neighborhoods. The results are comparable to those obtained via manual labeling but without the need for human intervention, saving time and effort.
Velocity Dispersion σ
aper Aperture Corrections as a Function of Galaxy Properties from Integral-field Stellar Kinematics of 10,000 MaNGA Galaxies
Authors: Zhu Kai , Li Ran , Cao Xiaoyue , Lu Shengdong , Cappellari Michele , Mao Shude
Published: May 2023

The second moment of the stellar velocity within the effective radius, denoted by

σ

e

2

, is a crucial quantity in galaxy studies, as it provides insight into galaxy properties and their mass distributions. However, large spectroscopic surveys typically do not measure σ
e directly, instead providing σ
aper, the second moment of the stellar velocity within a fixed fiber aperture. In this paper, we derive an empirical aperture correction formula, given by

σ

aper

/

σ

e

=

(

R

aper

/

R

e

)

α

, using spatially resolved stellar kinematics extracted from approximately 10,000 Sloan Digital Sky Survey–Mapping Nearby Galaxies at Apache Point Observatory integral field unit observations. Our analysis reveals a strong dependence of α on the r-band absolute magnitude M
r, g–i color, and Sérsic index n
Ser, where α values are lower for brighter, redder galaxies with higher Sérsic indices. Our results demonstrate that the aperture correction derived from previous literature on early-type galaxies cannot be applied to predict the aperture corrections for galaxies with intermediate Sérsic indices. We provide a lookup table of α values for different galaxy types, with parameters in the ranges of −18 > M
r > −24, 0.4 < g–i < 1.6, and 0 < n
Ser < 8. A Python script is provided to obtain the correction factors from the lookup table.
Variability of Young Stellar Objects in the Perseus Molecular Cloud
Authors: Wang Xiao-Long , Fang Min , Herczeg Gregory J. , Gao Yu , Tian Hai-Jun , Zhou Xing-Yu , Zhang Hong-Xin , Chen Xue-Peng
Published: May 2023

We present an analysis of 288 young stellar objects (YSOs) in the Perseus molecular cloud that have well defined g and r-band lightcurves from the Zwicky Transient Facility. Of the 288 YSOs, 238 sources (83% of our working sample) are identified as variables based on the normalized peak-to-peak variability metric, with variability fraction of 92% for stars with disks and 77% for the diskless populations. These variables are classified into different categories using the quasiperiodicity (Q) and flux asymmetry (M) metrics. Fifty-three variables are classified as strictly periodic objects that are well phased and can be attributed to spot modulated stellar rotation. We also identify 22 bursters and 25 dippers, which can be attributed to accretion burst and variable extinction, respectively. YSOs with disks tend to have asymmetric and non-repeatable lightcurves, while the YSOs without disks tend to have (quasi)periodic lightcurves. The periodic variables have the steepest change in g versus g − r, while bursters have much flatter changes than dippers in g versus g − r. Periodic and quasiperiodic variables display the lowest variability amplitude. Simple models suggest that the variability amplitudes of periodic variables correspond to changes of the spot coverage of 30%–40%, burster variables are attributed to accretion luminosity changes in the range of L
acc/L
⋆ = 0.1–0.3, and dippers are due to variable extinction with A

V
changes in the range of 0.5–1.3 mag.
Performance of FAST with an Ultra-Wide Bandwidth Receiver at 500–3300 MHz
Authors: Zhang Chuan-Peng , Jiang Peng , Zhu Ming , Pan Jun , Cheng Cheng , Liu Hong-Fei , Zhu Yan , Sun Chun , Collaboration FAST
Published: May 2023

The Five-hundred-meter Aperture Spherical radio Telescope (FAST) has been running for several years. A new ultra-wide bandwidth (UWB) receiver, simultaneously covering 500–3300 MHz, has been mounted in the FAST feed cabin and has passed a series of observational tests. The whole UWB band is separated into four independent bands. Each band has 1,048,576 channels in total, resulting in a spectral resolution of 1 kHz. At 500–3300 MHz, the antenna gain is around 14.3–7.7 K Jy−1, the aperture efficiency is around 0.56–0.30, the system temperature is around 88–130 K, and the half-power beamwidth is around 7.6′–1.6′. The measured standard deviation of pointing accuracy is better than ∼7.9″ when zenith angle is within 26.4°. The sensitivity and stability of the UWB receiver are confirmed to satisfy expectations through spectral observations, e.g., H i and OH. The FAST UWB receiver has already demonstrated good performance in capturing sensitive observations for various scientific goals.
Global Energetics of Solar Powerful Events on 2017 September 6
Authors: Li Dong , Warmuth Alexander , Wang Jincheng , Zhao Haisheng , Lu Lei , Zhang Qingmin , Dresing Nina , Vainio Rami , Palmroos Christian , Paassilta Miikka , Fedeli Annamaria , Dominique Marie
Published: May 2023

Solar flares and coronal mass ejections (CMEs) are thought to be the most powerful events on the Sun. They can release energy as high as ∼1032 erg in tens of minutes, and also can release solar energetic particles (SEPs) into interplanetary space. We explore global energy budgets of solar major eruptions that occurred on 2017 September 6, including the energy partition of a powerful solar flare, and the energy budget of the accompanying CME and SEPs. In the wavelength range shortward of ∼222 nm, a major contribution of the flare radiated energy is in the soft X-ray (SXR) 0.1–7 nm domain. The flare energy radiated at wavelengths of Lyα and mid-ultraviolet is larger than that radiated in the extreme ultraviolet wavelengths, but it is much less than that radiated in the SXR waveband. The total flare radiated energy could be comparable to the thermal and nonthermal energies. The energies carried by the major flare and its accompanying CME are roughly equal, and they are both powered by the magnetic free energy in the NOAA AR 12673. Moreover, the CME is efficient in accelerating SEPs, and the prompt component (whether it comes from the solar flare or the CME) contributes only a negligible fraction.
Decametric Solar Radio Spectrometer Based on 4-element Beamforming Array and Initial Observational Results
Authors: Guo Shao-Jie , Gao Guan-Nan , Shen Fa-Xin , Yang Feng-Hui , Dong Liang , Wang Min
Published: May 2023

The dynamic spectral observation at decametric wavelength is important to study solar radio physics and space weather. However, the observing system is difficult to observe with high sensitivity at this band due to the fact that the system temperature is dominated by the sky background noise and the antenna is difficult to design with high gain. An effective solution to improve the sensitivity is constructing an antenna array based on the beamforming method. Accordingly, we develop a decametric solar radio spectrometer system based on a 4-element beamforming array. The system consists of four antennas, an 8-channel analog receiver and a digital receiver. We use the true time delay to implement the beamformer and the classical FFT method to perform spectrum analysis in the digital receiver. Operating at a frequency range of 25–65 MHz with dual-circular polarizations, the system provides high resolution dynamic spectrum with spectral resolution of ∼12 kHz and temporal resolution of ∼5.3 ms (typical). Tens of solar radio bursts have been observed successfully during the period of the trial observation, demonstrating the system’s ability to detect fine structures with high spectral and temporal resolution. In this article, we present the design, implementation, and initial observational results of the decametric solar radio spectrometer system in detail.
Attention-Based Deep Learning Model for Image Desaturation of SDO/AIA
Authors: Zhang Xinze , Xu Long , Ren Zhixiang , Yu Xuexin , Li Jia
Published: May 2023

The Atmospheric Imaging Assembly (AIA) onboard the Solar Dynamics Observatory (SDO) captures full-disk solar images in seven extreme ultraviolet wave bands. As a violent solar flare occurs, incoming photoflux may exceed the threshold of an optical imaging system, resulting in regional saturation/overexposure of images. Fortunately, the lost signal can be partially retrieved from non-local unsaturated regions of an image according to scattering and diffraction principle, which is well consistent with the attention mechanism in deep learning. Thus, an attention augmented convolutional neural network (AANet) is proposed to perform image desaturation of SDO/AIA in this paper. It is built on a U-Net backbone network with partial convolution and adversarial learning. In addition, a lightweight attention model, namely criss-cross attention, is embedded between each two convolution layers to enhance the backbone network. Experimental results validate the superiority of the proposed AANet beyond state-of-the-arts from both quantitative and qualitative comparisons.
A New Emission Mode of PSR B1859+07
Authors: Wang Tao , Wang P. F. , Han J. L. , Yan Yi , Yu Ye-Zhao , Kou Feifei
Published: May 2023

Previous studies have identified two emission modes in PSR B1859+07: a normal mode that has three prominent components in the average profile, with the trailing one being the brightest, and an anomalous mode (i.e., the A mode) where emissions seem to be shifted to an earlier phase. Within the normal mode, further analysis has revealed the presence of two submodes, i.e., the cW mode and cB mode, where the central component can appear either weak or bright. As for the anomalous mode, a new bright component emerges in the advanced phase while the bright trailing component in the normal mode disappears. New observations of PSR B1859+07 using the Five-hundred-meter Aperture Spherical Radio Telescope (FAST) have revealed the existence of a previously unknown emission mode, dubbed the Af mode. In this mode, all emission components seen in the normal and anomalous modes are detected. Notably, the mean polarization profiles of both the A and Af modes exhibit a jump in the orthogonal polarization angle modes in the bright leading component. The polarization angles for the central component in the original normal mode follow two distinct orthogonal polarization modes in the A and Af modes respectively. The polarization angles for the trailing component show almost the same but a small systematic shift in the A and Af modes, roughly following the values for the cW and cB modes. Those polarization features of this newly detected emission mode imply that the anomalous mode A of PSR B1859+07 is not a result of “phase shift” or “swooshes” of normal components, but simply a result of the varying intensities of different profile components. Additionally, subpulse drifting has been detected in the leading component of the Af mode.
Comparison of current-voltage characteristics of molybdenum ditelluride and black phosphorene channel material based field effect transistor to optimize conductance
Authors: Shaik Z , Deepak A
Published: May 2023

The work aims to improve the current and conductance characteristics of Molybdenum ditelluride and Black phosphorene in a novel 2D Field Effect transistor for different thickness level of oxide from 1 nm to 10 nm. Materials and Methods: Molybdenum ditelluride and Black phosphorene channel-based Field Effect transistor was chosen as two groups having 16 samples each. The current characteristics were simulated by varying the oxide thickness. Reducing the oxide thickness of MOTE2 will lead to increased current and conductance characteristics. The novel 2D FET is simulated to obtain better current characteristics based on nanotechnology and reducing the oxide thickness of BP will lead to increased current and conductance characteristics in novel 2D FET. Results: MOTE2 based Novel 2D FET has higher conductance than BP based 2D FET. Gate oxide thickness was at 1 nm during maximum conductivity for MOTE2 based 2D FET and 10 nm for BP based Novel 2D FET in NanoHub simulation tool. The results were obtained with a level of significance value is 0.001 for current and 0.0001 for conductance, and pretest power value of 80% using SPSS tools. Conclusion: Within the limit of study, MOTE2 based Novel 2D Field-effect transistor has better current (2876.39) and conductance (9.587e-03) mho characteristics than BP based 2D FET current (1250.58) and conductance (4.168e-03) mho.
Optimizing the input parameters setting for least hole defects while drilling CFRP laminates by multi-objective optimization on the basis of ratio analysis (MOORA) method
Authors: Barik T , Parida S , Pal K
Published: May 2023

Carbon fiber reinforced plastic laminates have been kept under the category of hard-to-machine materials despite having some unmatchable properties like high strength, stiffness, corrosion resistance, etc. The heterogeneous nature of the material makes the essential secondary machining process a challenging task to perform. Drilling is always considered the effective way to drill holes necessary for the assembling purpose in structure building. Though, drilling the CFRP laminates critically affected by the abrasiveness of the reinforcing fibers eventually produces various defects. In this particular experimental analysis, a decision-making model associated with the Multi-objective optimization of ratio analysis (MOORA) method has been used in selecting the best possible parameter setting for minimizing defects. The results suggested that this method is found to be effective in solving the real-world problem of selecting the optimized parameter setting in drilling CFRPs. The best possible combination of low point angle, high speed, and low feed rate produces the least drilled hole defects.
Analysis of mechanical properties of 3D printed metallic specimens of aluminum (CL31) bronze (CL80) material manufactured at varying laser scanning speed
Authors: Vashist V , Oldal I , Szakal Z
Published: May 2023

In our research work, we analyzed the mechanical properties of 3D-printed metallic specimens of aluminium bronze material. In our evaluation, we had five groups of specimens, manufactured at different laser scanning speeds. In total, we had 25 specimens for which we examined various parameters like ultimate tensile strength, engineering yield point, relative strain, and hardness. Results showed that specimens prepared with a lower laser scanning speed of 300mm/s showed the lowest tensile strength. The tensile strength increased with increasing laser scan speed and the highest tensile strength was attained by specimens of the fourth group that were produced at a laser scanning speed of 500mm/s. The relative strain of specimens also increased with the increasing scan speed of the laser. The Brinell hardness test also showed an elevation in hardness values with increasing laser scan speeds.
X-Ray absorption fine structure study of schiff base cobalt (II) complexes of 5,5-dimethyl-2-(4-arylhydrazono) cyclohexane-1,3-dione
Authors: Agrawal Pankaj , Sharma Pradeep , Mishra Ashutosh
Published: May 2023

Hereby, we emphasize on X-Ray absorption fine structure of Schiff Base cobalt (II) complexes. The aryl groups studied were 4-bromophenyl and 4-nitrophenyl complexes. Different functional groups of complexes are confirmed by FTIR, and XRD demonstrates the crystalline structure of the compound. The chemical shift, the shift of K-edge and primary absorption maximum shift along with edge width have all been determined via XANES data analysis. In addition to this, we were calculated the ENC and percentage covalency. EXAFS data were used to calculate the first shell bond length using several graphical techniques. To get deep insight of bond length, we exploited the normalised Fourier transform spectra to derive information. Athena software was used to analyse the data. Origin software was employed to represent the data graphically.
Optimization of process parameters on wire cut electrical discharge machining and surface integrity studies of AA6070/MgO composites
Authors: Vinoth S , Rajasekar C , Sathish P , Sureshkumar V , Yasminebegum A , Hasane Ahammad Sk , Girimurugan R
Published: May 2023

There are a variety of uses for metal matrix composites (MMC), including the aerospace and automotive industries. Because of their benefits including light weight and inexpensive cost, they are popular. Wire cut electric discharge machining (WEDM) stands out as a great option for creating complex or complicated shapes out of composite materials, especially when compared to other common non-traditional machining processes. An AA6070 metal matrix composite containing 5% and 10% MgO weight fraction (wt) was made using the stir casting method in this work. Various process factors, such as wire tension (WT), dielectric pressure (Pd), gap voltage (Vg) and peak current (IP) are taken into account when the AMMC specimen is machined utilising WEDM. Slot machining rate (MR) and surface roughness (Ra) can be measured and assessed using L18 mixed Orthogonal Array (OA) investigations. Experiments are examined using TOPSIS and ANOVA methodologies for order preference based on similarity to the ideal results (ANOVA). Analysis has shown that the best mixture of processing factors for improved MR and Ra: wt = 5%, vg = 50 V, WT = 13 g, Ip = 9 A, and Pd = 15 bar. Machining Rate and Ra have ideal process parameters of 1.5 mm/min and 3.648 m. ANOVA shows that MR and Ra are significantly influenced by peak current.
Analysis of undulator and gyro-synchrotron radiation for application at tera-hertz
Authors: Mishra G. , Gehlot Mona , Gupta Vikesh
Published: May 2023

We analyze the undulator and gyro-synchrotron radiation of the devices by equating the number of periods of the helical trajectory of the gyrating motion to the number of undulator periods. The gyro radiation is characterized by cyclotron resonance maser interaction exhibits superior line width quality but higher sensitive to beam energy spread when operated at tera-hertz due to finite larmor radius effects.
Structural and optical properties of Magnesium borate phosphors for dosimetric purpose
Authors: Sharma R , Mehta M
Published: May 2023

The recent study presented the structural and optical features of Sm-doped magnesium borate. The X-ray diffraction pattern displays the crystal structure of the prepared sample which matches with the JCPDS card. The morphological studies, elemental analysis, and vibrational properties were examined by SEM, EDX, and FTIR measurements. The TL emission spectra of pure magnesium borate phosphors show only one peak at 209°c, and doped phosphors show an intense peak at 212°c. The PL excitation (PLE) spectrum of the MgB4O7: Sm samples was observed at a wavelength range of 330 – 475 nm. The maximum sharp line is detected nearly at 407 nm that corresponds to ions Sm3+ transition of 6H5/2 → 4K11/2 and the PL emission of the intense line was measured at a wavelength of 612 nm due to the significant excitation of Sm3+ ions from 4G5/2 to 6H7/2. In addition, the bonding behavior of synthesized phosphors was determined by Raman spectroscopy.
Reinforcement of micro and nano material with aluminum alloy (Al7075) metal matrix composite: a review
Authors: Koria Chandra Shekhar , Kumar Rajan , Chauhan Premanand S
Published: May 2023

The characteristics and structural performance of a composite material’s properties are better than those of its component parts because It comprised of a pair or more insoluble, chemically separate stages. functioning alone. ‘Metal-Matrix’ composites materials that have been produced from metals and ceramics had fibers or particles incorporated into them to enhance their physical characteristics. The fabrication of several parts and components in the aircraft and aerospace industry regularly uses aluminium 7075 alloy, a significant technical material. Its high strength to density ratio makes metal matrix composites very desirable. We provide an overview of Al 7075 Metal Matrix Composites in this study.
Performance analysis and mechanical behavior of aluminum metal matrix composite
Authors: Jerome Nithin Gladson G , Deepak Raj K , Devesh R , Jeeva Prakash R , Pandurangan S
Published: May 2023

The increased traits and qualities that composite materials provide in comparison to those of single materials have led to their widespread use across a variety of modern sectors (metals). In recent years, there has been a rise in the demand for high-performance aluminum metal matrix composites. This is mostly due to the improved mechanical characteristics of these composites, which are necessary for fulfilling the needs of sophisticated engineering applications. The mix of different types of reinforcing materials has a significant impact on the performance of these composites. With a tensile strength that is equivalent to that of certain steels, aluminum 7068 is one of the strongest aluminum alloys that are now available for purchase on the market. Heat treatment may be performed on this material, which is an aerospace alloy by another name. This project’s primary objective is to improve the mechanical properties of aluminum 7068 by incorporating three distinct compositions—silicon carbide (SiC), boron carbide (B4C), and titanium dioxide (TiO2)—into the metal matrix of aluminum 7068 using a process known as stir casting, and then determining the mechanical properties of each individual composition by putting them through a series of mechanical tests. Compositions are compared with one another and with those of unreinforced Al7068 based on the results of the tests, and an effective composition is determined for the purpose of further research.
Flow visualisation of water channel setup for supersonic flow analogy
Authors: Surya Kkumar R , Manigandan R , Gokul DJ
Published: May 2023

In the present study, flow over aerodynamics models is analysed in water channel flow to understand flow physics at affordable cost. The water channel flow visualization setup is constructed to analyse the analogy between Froude number and Mach number and flow visualization over various models is observed. In order to conduct the study, the shallow water speed is varied from 0.4 m/s to 0.6 m/s in the test section of water channel which will corresponds to the Froude number, Fr= 2. The water channel results will be finally validated to wind tunnel at Mach number, M=2. The velocity of water channel can be found by tracing the motion of suspended particles over shallow water at defined length and also by the volumetric flow rate. Several tests were conducted over a spike model to understand the flow visualization and videos were captured. The hydraulic jump and divergent angle in the water surface will be observed and validated with the corresponding shock angle in air medium. Failure analysis throughout the constructs are discussed to understand and resolve different problems faced with the specimen, test section along with camera setup. The present setup can be used multiple times for long duration to observe the flow visualization for undergraduate students.
A numerical and experimental investigation of mitigation of the vibration in a structure using single pendulum type mass damper
Authors: Natesan S , Ramasamy S
Published: May 2023

The main objective of the present work is that to construct a combined Pendulum Type Mass Damper (PTMD) in a structure to demonstrate the effect of damping of vibrations. In order to achieve this, a simple prototype has been developed. An inductive proximity sensor has been used to measure the vibrations of prototype with the PTMD system in terms of the induced voltage signal. The induced voltage signals have been acquired by using an Arduino UNO controller board. The experiments have been carried out to measure the amplitude of displacement of the vibrations in the structure in terms of voltage signals for two cases: (i) Without adding the damper or tuned mass and (ii) With adding the damper or tuned mass of 100 g, 150 g, 200 g, 250 g and 300 g respectively. However, this work reports the experimental results only for 250 g. The theoretical analysis of PTMD has been studied and presented in this paper. A numerical model for the combined pendulum type mass damper with the structure has been developed by using MATLAB SIMULINK. A series of simulations have been carried out for the various values the mass ratio, μ = 0, 0.25, 0.5, 0.75 and 1 to show the effect damper or tuned mass on the vibrations of the structure. The simulation results of amplitude of displacement of the structure have been analyzed and presented in both time domain and frequency domain. By keeping the same condition of experimental analysis of 250 g damper or tuned mass, the simulations have been carried out for two cases: (i) Without absorber mass (mass ratio, μ=0) and (ii) With a damper mass of 250 g (mass ratio, μ=0.33) in order to validate the experimental results.
Machining of aluminium 6063 alloy using high strength steel and titanium nitride novel coated drill tool using CNC and comparing the material removal rate
Authors: Jayaram Reddy P , Vinodh D
Published: May 2023

This study compares two tools, HSS M42 and TiN Coated twist drill bits, in order to determine which tool has the better material removal rate (MRR). Drill bits were of high speed steel (HSS M42) tool and use of Novel coating of Titanium Nitride on HSS tool in this study. The machining is done on a experimental specimen made of aluminium alloy AA6063. The material removal rate of both tools is measured in CNC drilling on two sets of 20 specimens each. Spindle speed, depth of cut, and feed were all controlled variables. G power 80% used for calculating sample size. SPSS software was used to record and analyse the results for both tools. The average MRR recorded for HSS M42 tool was 14.9803 mm3/s with a Standard deviation value 1.713221. This study has a significance value of 0.037 (p < 0.05) with a g power of 80%. The titanium nitride coated tool had an average MRR of 20.06995 mm3/s and 1.179870 standard deviation. The results were achieved at 0.037 significance, that is lower than 0.05. The titanium nitride coated drill bit has comparatively better MRR than the high speed steel drill bit in no-lubricant and no-coolant drilling circumstances, as per this study.
Comparing the performance of uncoated insert and TiC insert in CNC novel machining of LDX 2101 duplex stainless steel for minimizing surface roughness
Authors: Thiagarajan C , Yagnesh Mandu
Published: May 2023

By differentiating titanium carbide (TiC) tool and cemented carbide uncoated tool during the CNC machining of LDX 2101 steel, this experimental approach aims to diminish surface roughness (SR). The control group comprised uncoated inserts while the experimental group featured TiC inserts. These drilling parameters parameters were speed of cutting, rate of feed, and cut depth. The number of groups was 2, and there were 27 samples used for each group in the trials. The standard SR value for TiC inserts is 0.06778 µm, while that for uncoated inserts is 0.145880 µm. Between two inserts, there is an 0.01 significant difference (p<0.05). In agreement with the constraints of this work, LDX2101 duplex stainless steel has a higher SR when machined with a TiC insert and a lower SR when machined with an uncoated insert.
Computational analysis of influence of geometry on cfj airfoil aerodynamic coefficients
Authors: Vigneswaran C M , VishnuKumar G C
Published: May 2023

This research aims to examine the impact of the co flow jet (CFJ) airfoil profile on the aerodynamic coefficient through numerical analysis. The geometry of the CFJ airfoil is characterized by the placement and height of suction and injection slots. By adjusting it, the shape of a CFJ airfoil can be modified. Although the injection jet is the most essential factor in boosting the CFJ airfoil’s aerodynamic coefficient, the shape also plays a part in the lift augmentation process. The objective of this research is to study more about it. For this computational analysis, the Splarat Almaras turbulence model was chosen, and the flow is assumed as incompressible. The computational analysis is done through ANSYS 18.1 software. The structure of the CFJ airfoil changes as the location and dimension of suction and injection cavities are modified, which has a significant impact on the aerodynamic coefficients.
Assessment and comparison of thermal sensations for a traditional and modern building
Authors: Dębska L , Krawczyk N
Published: May 2023

The proper design of buildings should ensure that the indoor conditions are comfortable, and users experience thermal comfort throughout the year, especially in sophisticated, modern intelligent buildings. The existing model of thermal comfort comes from the 60’s/70’s and was the basis for the ISO 7730 Standard. It utilizes the concept of the PMV (Predicted Mean Vote) and PPD (Predicted Percentage Dissatisfied) indicators. The current paper compares the actual expressions of people (as indicated by them in the anonymous questionnaires) with the PMV/PPD values calculated according to the Standard. Differences between these values have been discussed and conclusions have been drawn as to the usability of this thermal comfort model in intelligent buildings, which still seem to be a novelty in Central European countries and data on their thermal comfort performance is still quite modest.
Traffic congestion control by monitor illegal parking and enabling intimation
Authors: Gomathi V , Sai Sumanth G , Charansai G , Charan Galla
Published: May 2023

The population growth is high, and day by day it increases in the world, there is also a huge growth towards technologies. The technologies aims at reducing the human workload by that it saves human time. In such case, the increase of automobiles in this generation is very high compared to the olden days. Due to the increase of such automobile, there is also a gradual increase in terms of traffic in the countries. We wait for a long time based on the traffic in the cities. The main cause for some traffic to occur is due illegal parking on roads and other areas. In order to beat this drawback, we tend to propose a way to avoid traffic. This paper is about giving a clear indication to the driver indicating the parking status of the driver’s vehicle. This methodology permits the reduction of congestion caused by misappropriated parking of vehicles.
Application access for chromatic color detection
Authors: Umarani V , Dimpusowjanya M , Poojitha Dodla , Sriya Gurijala Sai
Published: May 2023

The process of identifying specific examples of an item inside an image or video is referred to as “object detection,” and it is one of the computer vision techniques. When individuals look at pictures or movies, they are able to recognize and find things that are of interest to them. The primary goal of the field of object recognition is to achieve this level of intelligence via the use of a computer. Image segmentation and blob analysis, which uses simple object properties such as size, shape, or color, and Feature-based object detection, which uses feature extraction, matching, and RANSAC to estimate the location of an object, are two of the many common techniques that are used in conjunction with deep learning and machine learning-based object detection. There are also many other common techniques that are used in conjunction with deep learning and machine learning-based object detection. The most challenging aspects of object detection are the processes of categorizing things and pinpointing their locations. When seen from a different perspective, the same object might seem to be completely different. Detection algorithms have a tough time distinguishing between various things at different scales and perspectives since the sizes and proportions of items almost always alter. The camera input would be used to determine an object’s shape, according to this project’s proposal. Circle, square, and triangle are the three distinct shapes that we are determining an item to be right now. The finished result is shown in MATLAB’s graphical user interface (GUI). The productive identification process is carried out with the assistance of MATLAB. Using the SFTA Algorithm, the application extracts features from the specific image of a video. The neural network algorithm is used to classify the image of video. Image segmentation and image detection are two examples of related computer vision methods that are inextricably intertwined with object recognition. These techniques allow us to better comprehend and analyze the situations shown in movies and still photographs. It has been determined whether or not the suggested system is suitable. Because of this, the testing has shown that the suggested system generates generally accurate indications of real performance at a rate of 99.4%.