bluuebunny/crossref_metadata_2025_split huggingface dataset:
Elementary catastrophes underlying bifurcations of vector fields and PDEs
Authors: Jeffrey Mike R 
Published: June 2024

Abstract
A practical method was proposed recently for finding local bifurcation points in an n-dimensional vector field F by seeking their ‘underlying catastrophes’. Here we apply the idea to the homogeneous steady states of a partial differential equation as an example of the role that catastrophes can play in reaction diffusion. What are these ‘underlying’ catastrophes? We then show they essentially define a restricted class of ‘solvable’ rather than ‘all classifiable’ singularities, by identifying degenerate zeros of a vector field F without taking into account its vectorial character. As a result they are defined by a minimal set of r analytic conditions that provide a practical means to solve for them, and a huge reduction from the calculations needed to classify a singularity, which we will also enumerate here. In this way, underlying catastrophes seem to allow us apply Thom’s elementary catastrophes in much broader contexts.
Core inductive electric field during sawtooth crashes on DIII-D
Authors: Benedett T E , Chen J , Brower D L , Ding W X 
Published: June 2024

Abstract
Sawtooth crashes on tokamak plasmas exhibit relaxation much faster than resistive time scales via a mechanism not fully understood. Using core magnetic measurements from the Radial Interferometer-Polarimeter (RIP) diagnostic on the DIII-D tokamak, Grad–Shafranov equilibria constrained by internal magnetic measurements that have high time resolution (

<

1

µs) can be computed, allowing analysis of how equilibrium parameters such as safety factor q, current density J, and parallel electric field

E
∥

, particularly on-axis, evolve. At the sawtooth crash, on-axis safety factor q
0 is observed to rise by 5% but remain below 1 throughout the cycle, and on-axis current density J
0 is observed to drop by 5%. On-axis parallel electric field

E
∥

(
0
)

is found to be balanced by

η

J
0

(resistivity times on-axis current density) except during the 200 µs crash period, where

E
∥

(
0
)

reaches 22 V m−1, exceeding

η

J
0

by a factor of more than 2000. These first measurements in tokamak plasmas verify that generalized Ohm’s law is not balanced during the crash by resistive effects alone; this is a finding expected due to the relaxation being much faster than resistive timescales. Measurement of the electric field during the tokamak sawtooth serves to illuminate the physical mechanisms at work.
A statistical primer on classical period-finding techniques in astronomy
Authors: Giertych Naomi , Shaban Ahmed , Haravu Pragya , P Williams Jonathan 
Published: June 2024

Abstract
The aim of our paper is to investigate the properties of the classical phase-dispersion minimization (PDM), analysis of variance (AOV), string-length (SL), and Lomb–Scargle (LS) power statistics from a statistician’s perspective. We confirm that when the data are perturbations of a constant function, i.e. under the null hypothesis of no period in the data, a scaled version of the PDM statistic follows a beta distribution, the AOV statistic follows an F distribution, and the LS power follows a chi-squared distribution with two degrees of freedom. However, the SL statistic does not have a closed-form distribution. We further verify these theoretical distributions through simulations and demonstrate that the extreme values of these statistics (over a range of trial periods), often used for period estimation and determination of the false alarm probability (FAP), follow different distributions than those derived for a single period. We emphasize that multiple-testing considerations are needed to correctly derive FAP bounds. Though, in fact, multiple-testing controls are built into the FAP bound for these extreme-value statistics, e.g. the FAP bound derived specifically for the maximum LS power statistic over a range of trial periods. Additionally, we find that all of these methods are robust to heteroscedastic noise aimed to mimic the degradation or miscalibration of an instrument over time. Finally, we examine the ability of these statistics to detect a non-constant periodic function via simulating data that mimics a well-detached binary system, and we find that the AOV statistic has the most power to detect the correct period, which agrees with what has been observed in practice.
Extracting the speed of sound in quark–gluon plasma with ultrarelativistic lead–lead collisions at the LHC
Authors:   The CMS Collaboration
Published: June 2024

Abstract
Ultrarelativistic nuclear collisions create a strongly interacting state of hot and dense quark–gluon matter that exhibits a remarkable collective flow behavior with minimal viscous dissipation. To gain deeper insights into its intrinsic nature and fundamental degrees of freedom, we determine the speed of sound in an extended volume of quark–gluon plasma using lead–lead (PbPb) collisions at a center-of-mass energy per nucleon pair of 5.02 TeV. The data were recorded by the CMS experiment at the CERN LHC and correspond to an integrated luminosity of 0.607 nb−1. The measurement is performed by studying the multiplicity dependence of the average transverse momentum of charged particles emitted in head-on PbPb collisions. Our findings reveal that the speed of sound in this matter is nearly half the speed of light, with a squared value of

0.241
±
0.002

(
stat
)
±
0.016

(
syst
)

in natural units. The effective medium temperature, estimated using the mean transverse momentum, is

219
±
8

(
syst
)

MeV

. The measured squared speed of sound at this temperature aligns precisely with predictions from lattice quantum chromodynamic (QCD) calculations. This result provides a stringent constraint on the equation of state of the created medium and direct evidence for a deconfined QCD phase being attained in relativistic nuclear collisions.
Kresling origami derived structures and inspired mechanical metamaterial
Authors: Wang Xiaolei , Qu Haibo , Zhao Kai , Yang Xiao , Guo Sheng 
Published: June 2024

Abstract
Origami has attracted more and more attention due to its exotic mechanical properties, and the inspired metamaterials are also popular. However, the main focus of current research is on existing origami patterns and properties, although new origami patterns or results that expand on existing origami patterns are gradually emerging. In this paper, we summarize a series of derived structures of the Kresling origami, demonstrating more stable states and richer structural forms. At the same time, a point-searching method is proposed along the ideas of the truss model, which is effective for irregular stable states of these derived structures. On this basis, we create an origami-inspired mechanical metamaterial with foldable property and high load-bearing capacity, fabricate the prototype, and validate its performance through experiments. These works make important contributions for promoting the Kresling origami and origami-inspired metamaterials.
Low-frequency electrodynamics in the mixed state of superconducting NbN and a-MoGe films using two-coil mutual inductance technique
Authors: Basistha Somak , Mandal Soumyajit , Jesudasan John , Bagwe Vivas , Raychaudhuri Pratap 
Published: June 2024

Abstract
We investigate the low-frequency electrodynamics in the vortex state of two type-II superconducting films, namely, a moderate-to-strongly pinned Niobium Nitride (NbN) and a very weakly pinned amorphous Molybdenum Germanium (a-MoGe) film. We employ a two-coil mutual inductance technique to extract the complex penetration depth,

λ
~

. The sample response is studied through the temperature variation of

λ
~

in the mixed state, where we employ a model developed by Coffey and Clem (the CC model) to extract different vortex lattice (VL) parameters, such as the restoring pinning force constant (Labusch parameter), VL drag coefficient and pinning potential barrier. We observe that a consistent description of the inductive and dissipative part of the response is only possible when we take the viscous drag on the vortices to be several orders of magnitude larger than the viscous drag estimated from the Bardeen–Stephen model.
Competing interactions in strongly driven multi-level systems
Authors: Bender Jana , Mischke Patrick , Klas Tanita , Binoth Florian , Naim Hani , Ott Herwig , Niederprüm Thomas 
Published: June 2024

Abstract
We experimentally study the level mixing, splitting and repulsion of an optically driven atomic multi-level system under two competing interactions. The strength of the optical coupling is increased until it surpasses the atomic hyperfine interaction responsible for mixing the magnetic substates. Due to the multi-level character of the coupled state space, the level shifts exhibit complex behavior reminiscent of the Paschen–Back effect. Our results show that multi-level effects can have significant influence for strong external drive, differing from a simple model of effective non-interacting two-level systems. These results highlight the relevance of imperfections of the light polarization or initial state preparation in strongly optically driven systems.
Non-local time evolution equation with singular integral and its application to traffic flow model
Authors: Higashi Kohei 
Published: June 2024

Abstract
We consider an integro-differential equation model for traffic flow, which extends the Burgers equation model. To derive exact solutions to the equation, we first examine the features of integrable integro-differential equations and find that they are obtained through the residue formula from integrable equations in complex domains. Using this approach, we construct several new integrable equations with double singular integrals and elliptic singular integrals. Then, we discuss the traffic model and show that it exhibits interactions between free-flow and congested regions, as well as the deadlock phenomenon, depending on the non-locality parameter.
Optimizing surface finish in FDM-printed polycarbonate spur gears through abrasive flow finishing: insights from physics and material science perspectives
Authors: Meena Rajhans , Hashmi Abdul Wahab , Iqbal Faiz , Ahmad Shadab , Prakash Chander , Katiyar Jitendra Kumar , Mali Harlal Singh , Meena Anoj 
Published: June 2024

Abstract
In recent times, the usage of polymers has experienced notable growth across diverse manufacturing sectors. Polymeric gears, integral to automation, material handling systems, toys, and household appliances, have become ubiquitous. Although additive manufacturing techniques, especially Three-Dimensional (3D) printing, offer versatile applications, they grapple with challenges, notably poor surface finishing attributed to layer accumulation. This work explores the field of abrasive flow machining (AFM) in experimental settings using FDM-printed polymeric gears. The AFM medium concoction involves coal ash powder as the foundational material, EDM oil as the carrier fluid, and the infusion of glycerin as additives. Rigorous investigations were undertaken to pinpoint the optimal viscosity of the AFM medium and refine process parameters with a central focus on enhancing surface quality. A Taguchi L9 Design of Experiment (DOE) was meticulously crafted for parameter optimization using the Minitab statistical software. The investigation established a functional relationship between the output parameter (surface roughness) and key input variables (layer thickness, abrasive percentage, abrasive mesh size, and finishing time). The maximum level of AFM media optimization was attained at 33% abrasive concentration, 220 abrasive mesh size, and 60% liquid synthesizer. Additionally, the results of the investigation showed that a media viscosity of 0.50 Pa-sec, layer thickness of 0.1, and culminating time of 45 min were the optimal values for the most % improvement in surface roughness. The initial surface roughness underwent a profound reduction from 12.30 μm to 0.30 μm, marking an exceptional improvement of 97.56%. This inquiry contributes significant insights into the refinement of AFM parameters for elevating the surface finish of FDM-printed polymeric gears, promising enhanced performance across diverse applications.
MHD nonlinear thermally radiative Ag − TiO
2/H
2
O hybrid nanofluid flow over a stretching cylinder with Newtonian heating and activation energy
Authors: Rath Chinmoy , Nayak Anita 
Published: June 2024

Abstract
Hybrid nanofluids are significant in biomedical, industrial, transportation, as well as several engineering applications due to their high thermal conductivity and mass transfer enhancement nature in contrast to regular fluids and nanofluids. Taking this into consideration, the present problem explores the flow of hybrid nanofluid (Ag − TiO
2/H
2
O) over a stretching cylinder subject to Newtonian heat and mass conditions. The novel aspect of the current work is to analyze the heat and mass transfer characteristics of MHD hybrid nanofluid flow on Darcy-Forchheimer porous medium in addition to activation energy, nonlinear thermal radiation, heat generation/absorption, viscous and Joulian dissipation. Further, Silver (Ag) and Titanium oxide (TiO
2) are the constituent nanoparticles of the water-based hybrid nanofluid owing to their stable chemical features and extensive industrial manufacturing. By introducing suitable similarity transformations, the governing partial differential equations (PDEs) of the developed model are reduced to ordinary differential equations (ODEs), and then the numerical solution is procured with shooting technique by using MATLAB solver bvp4c. The influence of the pertinent parameters is depicted graphically and described elaborately. The analysis indicates that velocity exhibits a declining trend against the permeability and Forchheimer parameters, while the temperature profiles show opposite behavior. The radiation and conjugate heat parameters (R, γ
1) upgrade the heat transfer rate, while the curvature and conjugate mass parameters (α

c
, γ
2) amplify the mass transfer rate. The maximum heat transfer rate of Ag − TiO
2/H
2
O hybrid nanofluid is 2.3344 attained for γ
1 = 0.6. The investigation demonstrates larger heat and mass transfer rates for Ag − TiO
2/H
2
O hybrid nanofluid than Ag − H
2
O nanofluid. The outcomes of the present investigation have practical applications in conjugate heat transfer over fins, development of vaccines, effluent treatment plants, solar cells, heat exchangers, and many more. An excellent agreement is achieved on comparing our numerical results with the published results in the literature.
Cherenkov second harmonic generation of femtosecond laser pulses in a homogeneous nonlinear crystal
Authors: Vyunishev A M , Chirkin A S 
Published: June 2024

Abstract
In experiments on second harmonic (SH) generation (SHG), a conical structure of radiation has been observed. In the present study, a non-stationary theory of SH excitation of ultrashort laser pulses with phase modulation has been developed, which explains the properties of such a structure as Cherenkov radiation. Under phase-mismatched interactions, a maximum of the SH spectrum is observed at the Cherenkov angle, which is determined by the ratio of the SH and laser radiation phase velocities. It is shown that tightly focused laser beams are preferred to observe Cherenkov SHG. The SH spectral width depends on the group velocity mismatch and is more complicated on the excited radiation spectrum. The SH energy can be proportional to the crystal length or group delay length depending on their ratio. We also demonstrate that a complex angular distribution of spectral components (an angular chirp) appears within the SH cross-section.
Investigations on the interaction of laser parameters for efficient microdrilling of NiTiV smart alloy system
Authors: Arun A , Santosh S , Rajkumar K 
Published: June 2024

Abstract
Ni–Ti shape memory alloys (SMAs) are popular in current research due to their usefulness and mechanical properties. At different temperatures, Ni–Ti alloys transition from austenite to martensite. To restore high-temperature memory in nickel-titanium SMAs, vanadium (V) is added as an alloying element. For Ni–Ti-based SMAs, the fiber laser is one of the best machining procedures for bio-implants, actuators, and aircraft engine parts. Using a Box–Behnken design to experiment with laser power, nozzle distance, cutting speed, and frequency, this study examines fiber laser micro-drilled Ni50Ti48V2 SM alloy material removal and hole taper angle. By increasing power (P), frequency (F), and cutting speed (C
S
), Ni50Ti48V2 alloy material removal rate (MRR) increased by 75.79%. The hole taper angle (HTA) dropped 75.33% when cutting speed, laser power and frequency decreased. Lowering cutting speed and laser power increases micro-hole circularity and reduces HTA. Upon surface topographical inspection, debris and molten materials were found on the drilled surface. The flow of nitrogen gas caused materials to diffuse on the Ni50Ti48V2 alloy’s entry and exit surfaces, changing surface roughness. High parameters influence surface roughness, HTA, and circularity due to nitrogen gas flow. The material’s DSC and XRD tests confirmed its suitability for biomedical microhole production.
Different topological phase transitions in the Su–Schrieffer–Heeger model under different disorder structures
Authors: Gu 古 Yan 燕 , Lu 陆 Zhanpeng 展鹏 
Published: June 2024

Abstract
We investigate the topological phase transition in the Su–Schrieffer–Heeger model with the long-range hopping and quasi-periodic modulation. By numerically calculating the real-space winding number, we obtain topological phase diagrams for different disordered structures. These diagrams suggest that topological phase transitions are different by selecting the specific disordered structure. When quasi-periodic modulation is applied to intracell hopping, the resulting disorder induces topological Anderson insulator (TAI) phase with high winding number (W = 2), but the topological states are destroyed as the disorder increases. Conversely, when intercell hoppings are modulated quasi-periodically, both TAI phase and the process of destruction and restoration of topological zero modes can be induced by disorder. These topological states remain robust even under strong disorder conditions. Our work demonstrates that disorder effects do not always disrupt topological states; rather, with a judicious selection of disordered structures, topological properties can be preserved.
Successful prediction of tokamak transport in the L-mode regime
Authors: Staebler G.M. , Park J.M. , Hassan E. , Angioni C. , Fable E. , Bourdelle C. , Kinsey J.E. , Holland C. , Belli E.A. , Neiser T. , Candy J. , Waltz R.E. 
Published: June 2024

Abstract
A long standing shortfall in the predicted L-mode edge energy transport by reduced quasi-linear models of gyrokinetic turbulent transport has been resolved. The improved model TGLF-SAT2 has higher fidelity to gyrokinetic simulations of the electron-scale contribution to the electron energy transport and the ion-scale flux surface shape dependence of energy transport. The success of TGLF-SAT2 in predicting the L-mode and Ohmic edge profiles is critical to whole pulse simulation and opens the door to prediction of the H-mode power threshold.
Gyrokinetic simulations of electrostatic microturbulence in ADITYA-U tokamak with argon impurity
Authors: Singh Tajinder , Shah Kajal , Sharma Deepti , Ghosh Joydeep , Jadeja Kumarpalsinh A. , Tanna Rakesh L. , Chowdhuri M.B. , Lin Zhihong , Sen Abhijit , Sharma Sarveshwar , Kuley Animesh 
Published: June 2024

Abstract
The effect of impurity on the electrostatic microturbulence in ADITYA-U tokamak is assessed using global gyrokinetic simulations. The realistic geometry and experimental profiles of the ADITYA-U are used, before and after argon gas seeding, to perform the simulations. Before the impurity seeding, the simulations show the existence of the trapped electron mode (TEM) instability in three distinct regions on the radial-poloidal plane. The mode is identified by its linear eigenmode structure and its characteristic propagation in the electron diamagnetic direction. The simulations with Ar1+ impurity ions in the outer-core region show a significant reduction in the turbulence and transport due to a reduction in the linear instability drive, with respect to the case without impurity. A decrease in particle and heat transport in the outer-core region modifies the plasma density profile measured after the impurity seeding. It, thus, results in the stabilization of the TEM instability in the core region. Due to the reduced turbulence activity, the electron and ion temperatures in the central region increase by about 10%.
Large agri-food corporations in the global staple and cash crops markets: a quantitative analysis of rice and coffee through the virtual water perspective
Authors: Baronchelli Adelaide , Vallino Elena , Dalmazzone Silvana , Ridolfi Luca , Laio Francesco 
Published: June 2024

Abstract
The paper investigates the influence of major food corporations on global rice and coffee markets from 2013 to 2022, with a focus on market presence and water usage. It uses detailed data from the Euromonitor Passport and the CWASI datasets to analyze environmental impacts and virtual water (VW) flows at the company level, addressing gaps in the existing literature. Key findings show that although rice sales are larger than those of coffee in quantity, coffee embeds a higher total water use due to its greater unit water footprint (WF). The rice market is less internationalized and concentrated compared to the coffee market, where a few companies hold significant market shares across multiple countries. In 2022, the top 12 rice-selling companies control 16% of the global rice WF, exceeding the combined WF of the top three rice-importing nations. Similarly, the top 15 coffee-selling companies command 55% of the global roasted coffee WF, with significant disparities in VW quantities compared to major importing nations. The coffee market exhibits a higher number of companies with larger shares of WF than volumes, with this disparity increasing over time. Furthermore, more countries exhibit high and moderate concentration indices for coffee sales compared to rice. These findings highlight the considerable concentration of water resources among large companies, particularly in the coffee sector. The paper emphasizes the importance of considering the environmental implications of corporate activities in food supply chains, providing valuable insights for sustainability efforts in the agri-food industry.