bluuebunny/crossref_metadata_2025_split huggingface dataset:
Investigating the effect of coolant on cooling rate of engine oil used in automobile industry using Arduino interfaced temperature sensor
Authors: Pandey Amit Kumar , Sharma Raghav , Nikhil  , Choudhary Divyanshu , Bali Neha Batra , Verma Maya , Menon Rashmi , Tanwar Amit 
Published: February 2024

Abstract
Heat is lost by the system due to temperature difference between the hot object and surroundings. Two models which explain cooling are conduction-convection method and radiation method. During an automobile engine operation, both engine and engine oil get heated up. To overcome the problem of excessive heat generated, coolant is used to cool down the system. In present study, cooling rate of engine oil kept at high temperature was studied in the absence and presence of coolant. In the absence of coolant, engine oil follows the natural law of cooling stated by Newton and follows the exponential decay in temperature. Cooling rate constant was estimated through fitting first order and second order exponential decay with experimental data and found to be

3.35
×

10

−
4

s

−
1

and

2.39
×

10

−
4

s

−
1

(in first

50

min) respectively. Cooling rate in the presence of coolant was studied which shows rapid decrease in temperature for first few minutes which may be attributed to high heat capacity of coolant which surrounds the hot engine oil. After 50 min of cooling, temperature of both fluids found to decrease exponentially. Thus, the use of coolant was found to absorb the heat content from the engine oil rapidly in comparison to natural environment. Cooling rate constant were estimated through fitting experimental data and found to be

2.44
×

10

−
4

s

−
1

and

2.43
×

10

−
4

s

−
1

for engine oil and coolant respectively. The percentage change in temperature of oil in first two minutes in the presence of coolant was about 70% which is much higher in comparison to cooling without the use of coolant which was about 16% only. For data acquisition of temperature of engine oil and coolant, MAX6675 module with K-type thermocouple is used which were interfaced with the Arduino board.
Teaching the asynchronous general physics course in a crisis context: a case study at Igor Sikorsky Kyiv Polytechnic Institute
Authors: Savchenko Dariya , Chyzhska Tetyana , Shtofel Olha 
Published: February 2024

Abstract
The imposition of martial law and power outages in Ukraine made the first semester of the 2022/2023 academic year at Igor Sikorsky Kyiv Polytechnic Institute a challenge for lecturers and students, especially in learning the general physics course. An asynchronous learning mode became the only possible form in such a situation, so the problem of increasing the efficiency of conducting a lecture, problem sessions, and laboratory work in general physics arose. This study aims to describe the implementation of the discipline of general physics (part 1) promoted in an asynchronous mode by lecturers of the Department of General Physics and Modeling of Physical Processes. We verified that in crisis conditions, it is essential to: (i) provide students with all the necessary material on Moodle course and YouTube channel, allowing them to learn the theoretical material, solve the homework problems, and analyse the data from laboratory work, (ii) give feedback and consultations to students via Zoom/Telegram chat upon request, (iii) give the possibility to perform the laboratory work both in the virtual regime and as YouTube demonstration. The results of the survey of 82 students who studied the general physics course taking into account the recommendations mentioned above revealed that the majority of the surveyed students were completely/to a greater extent satisfied with the level of organisation of asynchronous learning, as well as the level of knowledge obtained, which undoubtedly indicates the effectiveness and efficiency of the proposed approach.
Improved resistive switching characteristics of solution processed ZrO2/SnO2 bilayer RRAM via oxygen vacancy differential
Authors: Choi Kihwan , Pak James Jungho 
Published: February 2024

Abstract
In this study, a solution-processed bilayer structure ZrO2/SnO2 resistive switching (RS) random access memory (RRAM) is presented for the first time. The precursors of SnO2 and ZrO2 are Tin(Ⅱ) acetylacetonate (Sn(AcAc)2) and zirconium acetylacetonate (Zr(C5H7O2)4), respectively. The top electrode was deposited with Ti using an E-beam evaporator, and the bottom electrode used an indium–tin–oxide glass wafer. We created three devices: SnO2 single-layer, ZrO2 single-layer, and ZrO2/SnO2 bilayer devices, to compare RS characteristics such as the I–V curve and endurance properties. The SnO2 and ZrO2 single-layer devices showed on/off ratios of approximately 2 and 51, respectively, along with endurance switching cycles exceeding 50 and 100 DC cycles. The bilayer device attained stable RS characteristics over 120 DC endurance switching cycles and increased on/off ratio ∼2.97 × 102. Additionally, the ZrO2/SnO2 bilayer bipolar switching mechanism was explained by considering the Gibbs free energy (ΔG
o) difference in the ZrO2 and SnO2 layers, where the formation and rupture of conductive filaments were caused by oxygen vacancies. The disparity in the concentration of oxygen vacancies, as indicated by the Gibbs free energy difference between ZrO2 (ΔG
o = −1100 kJ mol−1) and SnO2 (ΔG
o = −842.91 kJ mol−1) implied that ZrO2 exhibited a higher abundance of oxygen vacancies compared to SnO2, resulting in improved endurance and on/off ratio. X-ray photoelectron spectroscopy analyzed oxygen vacancies in ZrO2 and SnO2 thin films. The resistance switching characteristics were improved due to the bilayer structure, which combines a higher oxygen vacancy concentration in one layer with a lower oxygen vacancy concentration in the switching layer. This configuration reduces the escape of oxygen vacancies to the electrode during RS.
TMD material investigation for a low hysteresis vdW NCFET logic transistor
Authors: Blessing Meshach Dason I , Kasthuri N , Nirmal D 
Published: February 2024

Abstract
Boltzmann limit is inevitable in conventional MOSFETs, which prevent them to be used for low-power applications. Research in device physics can address this problem by selection of proper materials satisfying our requirements. Recently, 2D transition metal di-chalcogenide (TMD) materials are gaining interest because they help alleviate short-channel effects and DIBL problems. The TMD materials are composed by covalently bonded weak van der Waals (vdW) interaction and can be realized as hetero structures with 2D ferro-electric material CuInP2S6 at the gate stack. This paper demonstrates a vdW negative capacitance field effect transistor (NCFET) structure in TCAD and the design was validated for voltage-current Characteristics. Parametric analysis shows MoS2 with phenomenal on/off ratio, narrow hysteresis than the counterparts. Simulation shows that MoS2 vdW NCFET has a high transconductance of 2.36 µS µm−1. A steep slope of 28.54 mV dec−1 is seen in MoS2 vdW NCFET which promises the performance of logic applications at a reduced supply voltage.
Hall conductance of a non-Hermitian Weyl semimetal
Authors: Dey Soumi , Banerjee Ayan , Chowdhury Debashree , Narayan Awadhesh 
Published: February 2024

Abstract
In recent years, non-Hermitian (NH) topological semimetals have garnered significant attention due to their unconventional properties. In this work, we explore one of the transport properties, namely the Hall conductance of a three-dimensional dissipative Weyl semi-metal formed as a result of the stacking of two-dimensional Chern insulators. We find that unlike Hermitian systems where the Hall conductance is quantized, in presence of non-Hermiticity, the quantized Hall conductance starts to deviate from its usual nature. We show that the non-quantized nature of the Hall conductance in such NH topological systems is intimately connected to the presence of exceptional points. We find that in the case of open boundary conditions, the transition from a topologically trivial regime to a non-trivial topological regime takes place at a different value of the momentum than that of the periodic boundary spectra. This discrepancy is solved by considering the non-Bloch case and the generalized Brillouin zone (GBZ). Finally, we present the Hall conductance evaluated over the GBZ and connect it to the separation between the Weyl nodes, within the non-Bloch theory.
Emergence of first-order and second-order phase transitions in a cyclic ecosystem exposed to environmental impact
Authors: Bhattacharyya Sirshendu 
Published: February 2024

Abstract
A cyclically dominating three-species ecosystem, modeled within the framework of rock-paper-scissor game, is studied in presence of natural death and an effect of the environment. The environmental impact is parameterized along with the death rates in the rate equation of the species densities. Monte-Carlo simulations on this system reveal that the population density bears the signature of first-order and second-order phase transitions in different regimes of the parameters representing natural deaths of the species. The connection of this phenomena with the phase transitions is also supported by the behavior of the basin entropy calculated for the system. The density of total population evidently becomes an order parameter with respect to the change in environmental impact on the system.
Study of the photothermal response of a multilayer structure doped with VO2@Au nanoshells
Authors: Pulford Megan , Hatef Ali 
Published: February 2024

Abstract
In this paper, we demonstrate a theoretical study of a multiphysics problem to solve for the photothermal response of a one-dimensional multilayer structure containing a layer doped with VO2@Au nanoshells. The VO2@Au nanoshell consists of a gold (Au) shell and a core of the phase change material vanadium dioxide (VO2) where the VO2 core transitions from a semiconductor state to a conductor state at the critical temperature of 68 °C. This behaviour results in thermal induced optical tunability through this reversible phase change of the VO2, due to the temperature dependent optical and thermal properties. The presence of the VO2 core, functioning as an ultra-fast and reversible optical phase-change material, leads to the emergence of photothermal induced bistability. The layer doped with the VO2@Au nanoshell is approximated as an effective medium using the Maxwell-Garnett Theory to enable an analytical solution. In this study, the optical response of the multilayer structure is obtained using the Transfer Matrix Method, while the thermal response for both stationary and transient states is solved using the Green’s Function Method and Kirchhoff’s Transformation. These equations are interconnected through the heat source term in the heat diffusion equations, representing the local heat generation induced by the continuous-wave laser applied to the structure. Our findings indicate that at the wavelengths of 658 nm and 747 nm, there are two distinct photothermal responses arising from the phase change of the VO2 core. At these wavelengths, the absorption of light increases and decreases, respectively, because of the VO2 phase change. This analytical method not only offers a thorough exploration of the fundamentals of induced photothermal responses in multilayer structures but also holds considerable potential for various applications, including solar cells, photothermal therapy, and nanothermal sensors.
Higher rogue and rogue-soliton interaction solutions of a (2 + 1) dimensional nonlinear model in fluid mechanics
Authors: Cao Na , Yin XiaoJun , Xu LiYang , Bai ShuTing 
Published: February 2024

Abstract
In this study, two new theorems are generalized. We obtained a new paradigm about the second order rogue wave and multiple exponential functions, and a new paradigm about the second order rogue wave and multiple hyperbolic cosine functions. Six sets of interaction solutions of the model are solved by means of symbolic calculation and two new theorems. Meaningful graphs of the propagation processes along time demonstrated the interaction phenomena for these solutions. The energy transfer process can be observed when the second order rogue waves interact with multiple exponential functions or multiple hyperbolic cosine functions. As a conclusion from our paper, the solitons’ energy transfers to the second order rogue wave at beginning, the rogue wave’s energy dissipates and transfers to the solitons along the time moving. It will contribute to the research on the generation of rogue waves.
Solar radio spectrogram segmentation algorithm based on improved fuzzy C-means clustering and adaptive cross filtering
Authors: Liu Yan , Shen Yu Peng , Song Hong Qiang , Yan Fa Bao , Su Yan Rui 
Published: February 2024

Abstract
Solar radio spectrograms contain essential information, such as the duration type; therefore, recognizing and detecting solar radio spectrograms are significant for the further study of solar radio. With the upgrading of solar radio observation, considering the equipment that has already generated amounts of data, researchers have begun to use machine learning methods to recognize and detect solar radio spectrograms to resolve the weaknesses of manual identification, such as time consumption. However, the spectrograms are characterized by noise or insignificant outburst features, which affect the recognition and detection of solar radio spectrograms. In contrast, extracting the burst region separately and the more distinctive spectrogram features will help identify and detect it. Therefore, to remove the burst domain of the radio spectrogram better, this paper combines the idea of image segmentation and proposes a solar radio spectrogram segmentation algorithm based on improved fuzzy C-means (FCM) clustering and adaptive cross filtering for the extraction of the burst domain of solar radio spectrograms. This algorithm has multiple processing steps. The first step is solar radio spectrogram segmentation with the improved FCM based on the kernel-induced distance by incorporating spatial constraints combined with random walk and adaptive affiliation linking (RWAKFCM_S). The second step is adaptive cross filtering, eliminating the noise clustered in bursts. The results show the following. (1) The RWAKFCM_S proposed in this paper has better anti-noise and segmentation performance than other methods in the synthetic, natural, and solar radio spectrogram segmentation experiments; it can also overcome the problems of noise sensitivity when segmenting spectrograms by traditional FCM. (2) The RWAKFCM_S can satisfy the high accuracy and rate of solar radio spectrogram segmentation demands. (3) The adaptive cross filtering proposed in this paper can eliminate noise clustered in the eruption domain. (4) The proposed method enables burst region extraction.
Study of exponential wormhole metric in f(R) gravity
Authors: Nath Partha Pratim , Sarma Debojit 
Published: February 2024

Abstract
In this work, we have studied ‘the exponential form’ of space-time metric in some of the viable f(R) gravity models, viz. exponential gravity model, Starobinsky gravity model, Tsujikawa model, and Gogoi-Goswami f(R) gravity model. Here, we have calculated the parameters including energy density, tangential pressure, and radial pressure for these corresponding models of f(R) gravity. Subsequently, we have investigated the energy conditions, viz. null energy condition (NEC), weak energy condition (WEC), strong energy condition (SEC), and dominant energy condition (DEC) for the considered models. We have also explained the suitable stability conditions for these models through related plots. We observed that the exponential wormhole metric obeys all the necessary energy conditions in f(R) gravity without violating any flare-out or stability conditions. Out of four considered viable f(R) gravity models, the exponential, the Tsujikawa, and the Gogoi-Goswami f(R) gravity models are found to be more suitable for the exponential wormhole to exist, although all these models have some constraints on the ranges of the parameters used.
Time Variability of FUV Emission from Cool Stars on Multi-year Timescales
Authors: Kamgar Leo , France Kevin , Youngblood Allison 
Published: February 2024

Abstract
The physical and chemical properties of planetary atmospheres are affected by temporal evolution of ultraviolet (UV) radiation inputs from their host stars at all time scales. While studies of X-ray/UV flare properties and long-term stellar evolution of exoplanet host stars have provided new constraints regarding stellar inputs to exoplanetary systems, the UV temporal variability of cool stars on the timescale of stellar cycles remains largely unexplored. To address this gap in our understanding of the UV temporal variability of cool stars, we analyze far-ultraviolet (FUV) emission lines of ions that trace the chromosphere and transition region of nearby stars (C ii, Si iii, Si iv, and N v; formation temperatures ∼ 20–150 kK) using data from the Hubble Space Telescope (HST) and International Ultraviolet Explorer (IUE) archives spanning temporal baselines of months to years. We select 33 unique stars of spectral types F-M with observing campaigns spanning over a year, and create ionic light curves to evaluate the characteristic variability of cool stars on such timescales. Screening for large flare events, we observe that the relative variability of FUV light curves decreases with increasing stellar effective temperature, from 30% to 70% variability for M-type stars to <30% variability for F and G-type stars. We also observe a weak trend in the temporal variability with the Ca ii

R

HK

′

stellar activity indicator, suggesting that stars with lower Ca ii activity exhibit a smaller range of FUV flux variability. Screening for data sets with optimal temporal spread, and a sufficient number of individual observations, we select 5 data sets for further periodicity analysis (HST α Centauri A, HST α Centauri B, IUE α Centauri B, IUE ϵ Eri, IUE ξ Boo). Various periodic structures within the FUV flux were detected, with most significant being a 79 days frequency present within the IUE observations of ξ Boo, with a significance of 6σ, and a periodic signal in the FUV observations of α Centauri B, for both HST and IUE measurements, at ≈210 days frequency with significance of 3σ and 3.7σ, respectively. Our results suggest that extreme ultraviolet flux from cool stars varies by less than a factor of two on decade timescales, significantly smaller than variations on flare or stellar evolutionary timescales.
Optical Transient Source AT2021lfa: A Possible “Dirty Fireball”
Authors: Ye Xue-Mei , Wei Da-Ming , Zhu Yi-Ming , Jin Zhi-Ping 
Published: February 2024

Abstract
AT2021lfa, also known as ZTF21aayokph, was detected by the Zwicky Transient Facility on 2021 May 4, at 05:34:48 UTC. Follow-up observations were conducted using a range of ground-based optical telescopes, as well as Swift/XRT and VLA instruments. AT2021lfa is classified as an “orphan afterglow” candidate due to its rapid flux decline and its reddened color (g − r = 0.17 ± 0.14 mag). For an optical transient source without prompt gamma-ray detection, one key point is to determine its burst time. Here we measure the burst time through fitting the initial bump feature of AT2021lfa and obtain its burst time as 2021 May 3, at 22:09:50 UTC. Using afterglowpy, we model the multi-band afterglow of AT2021lfa and find that the standard model cannot reproduce the late radio observations well. Considering that the microphysical parameters ϵ

e
, ϵ

B
(the energy fraction given to electrons and magnetic field), and ξ

N
(the fraction of accelerated electrons) may vary with time, we then model the afterglow of AT2021lfa taking into account the temporal evolution of the physical parameters ϵ

e
, ϵ

B
, and ξ

N
and find in this case the multi-wavelength observations can be reproduced well. The initial Lorentz factor of AT2021lfa can be estimated from the peak time of the early afterglow, which yields a value of about 18, suggesting that AT2021lfa should be classified as a “dirty fireball.” From the upper limit for the prompt emission energy of AT2021lfa, we obtain that the radiation efficiency is less than 0.02%, which is much smaller than that of ordinary gamma-ray bursts (GRBs). It is also interesting that the fitted values of jet angle and viewing angle are very large, θ

c
∼ 0.66 rad, θ

v
∼ 0.53 rad, which may lead to the low Lorentz factor and radiation efficiency. When compared with GRB afterglow samples, it is evident that the onset bump timescale of AT2021lfa satisfies the empirical relationships observed in GRB samples. Additionally, the luminosity of AT2021lfa falls within the range of observations for GRB samples; however, approximately 1 day after the burst, its luminosity exceeds that of the majority of GRB samples.
Wearable System for Intelligent Monitoring of Assistance and Rescue Dogs
Authors: Chi-Pérez W D , Ríos-Martínez J A , Madera-Ramírez F A , Estrada-López J J 
Published: February 2024

Abstract
Dogs are remarkable animals that can form strong social bonds with humans and excel in various sensory abilities. These qualities make them suitable for training in different domains such as assistance, search, and rescue. However, current training methods are complex, costly, and lengthy because they depend on the trainer’s subjective interpretation of the dog’s behaviour. A more objective and efficient way to train dogs would be to monitor their vital signs and use artificial intelligence to infer their adaptation and progress. In this paper, we propose a wearable system that measures the dog’s vital signs and motion and wirelessly transmits the data to a computer. We test and analyse the performance of our system prototype and discuss its implications for dog training.
Experimental and theoretical heat transmission through a skin phantom using a Ruby IR therapeutic lamp.
Authors: Monsibais Silva E. , Zapata Torres M. , Valaguez Velazquez E. 
Published: February 2024

Abstract
A skin phantom model was developed and characterized to study the interaction of infrared radiation during photothermal therapy. The phantom consists of a platinum silicone matrix with polyethylene oxide containing encapsulated sodium alginate to mimic the concentration of water in human skin. The specific heat and thermal conductivity of each component were experimentally measured. A theoretical model was built with heat transfer equations to simulate the temperature distribution. The experimental results and numerical simulations show that the interaction phenomenon with infrared radiation is superficial, concentrating mostly in the epidermis and part of the dermis. This successfully replicates the actual thermal behaviour of the skin during photothermal therapy. The developed phantom adequately represents the thermal properties and response to infrared radiation of the skin, allowing its use as a surrogate model in thermal imaging and diagnostic applications.
Evaluation of 8-bit eDRAM by varying the aspect ratio of the in-cell transistors
Authors: Rodríguez-Ibarra I. , Argüelles-Lucho P. , Osorio-de-la-Rosa E. , Algredo-Badillo I. , López-Huerta Francisco 
Published: February 2024

Abstract
Embedded dynamic random-access memories (eDRAM) are widely used in the design of embedded systems for the safeguard of information during their operation. However, since these memories are installed in the same chip as the host system, it is crucial to consider their dimensioning. For this reason, in our work, the aspect ratio width and length (W/L) of complementary metal oxide semiconductor (CMOS) transistors inside 3-transistor logic cells (3T) is diversified to evaluate the effect on electrical behavior with area optimization through the figure of merit (FoM): power consumption-delay product of 8-bit memories with an operating frequency of 8.3 MHz, varying the aspect ratio of transistors inside the cell have been obtained 8.6f as lowest and 152.3f as highest FoM values. Those storage devices have been developed on 0.00085 mm2 using a 180-nm CMOS technology.