bluuebunny/crossref_metadata_2025 huggingface dataset:
Mechanisms of ignition and combustion instability in a scramjet combustor with micro-rocket torch using dynamic mode decomposition
Authors: Ogawa S.
Published: October 2024

Achieving ignition and stable combustion in scramjet combustors, which have residence times of milliseconds, requires effective flame stabilization. Previous studies have explored stable forced ignition and flame holding using various igniters, such as micro-rocket and plasma jet torches. This study investigated the forced ignition and combustion instability of a scramjet combustor with a micro-rocket torch. Although the micro-rocket torch successfully ignited the combustor in previous experiments, combustion instabilities were observed in the cavity flame holder through OH* chemiluminescence images. To understand the mechanisms behind forced ignition and combustion instability, dynamic mode decomposition (DMD) was employed. DMD is effective for analyzing combustion dynamics because it extracts spatiotemporally coherent structures from high-dimensional data. The OH* chemiluminescence images from prior experiments were analyzed using DMD to identify the dominant modes associated with the combustion instability. Power spectrum density analysis revealed that low-frequency instabilities (100–400 Hz) were caused by fuel injector flame feedback, very low frequencies (15–50 Hz) were due to torch gas injector flame feedback, and high frequencies (over 1000 Hz) resulted from interference between the cavity flame holder and the flow field. These findings provide insights into the complex flow dynamics within the cavity flame holder and shear layer, thereby enhancing the understanding of combustion instability mechanisms in scramjet engines equipped with micro-rocket torches.
Impact of scaling and upper/lower wall friction on the behavior of sweeping jet actuators (SJAs)
Authors: Yang Pengcheng , Chen Shaowen , Shi Yanchun , Chen Shuaitong
Published: October 2024

A series of numerical simulations using the unsteady Reynolds-averaged Navier–Stokes (URANS) method were conducted in the current study to investigate the effects of scaling on the sweeping and frequency characteristics of sweeping jet actuators (SJAs). Three different scales of SJAs, with hydraulic diameters of 1.6, 2.9, and 4.2 mm, respectively, were examined to assess variations in maximum sweeping angle, root-mean square (RMS) values of the transient sweeping angle, and operating frequency under different Reynolds numbers. Additionally, the influence of friction from the upper and lower walls of SJA on its performance was studied by comparing SJAs with different heights (aspect ratio = 1, 0.67, and 0.38) and configurations where the upper and lower walls were set as free slip walls. The results demonstrate that the reduction in SJA scale leads to significant changes in sweeping characteristics, with the maximum sweeping angle decreasing by more than 10° and the normalized RMS value of the sweeping angle distribution also notably decreasing. The frequency characteristics were analyzed by examining the size of the separation bubble in the mixing chamber and the average velocity in the feedback channel, showing variations with scale changes. Additionally, it was found that the friction from the upper and lower walls plays a crucial role in the performance changes observed when the SJA scale is altered. These findings suggest that the impact of performance changes should be carefully considered in the design of SJAs for specific applications, and appropriate adjustments should be made as necessary.
Mechanochemical synthesis of double-filled p-type Yb0.75Ce0.25Fe3.5Co0.5Sb12 skutterudites
Authors: Chernyshova Evgeniya , Shcherbakova Kseniia , Argunov Efim , Bochkanov Fedor , Kuznetsov Yuri , Dorokhin Mikhail , Khovaylo Vladimir
Published: October 2024

Skutterudites are one of the most efficient materials for use in thermoelectric applications. From an industrial point of view, along with the high efficiency of thermoelectric materials, it becomes actual to develop a rapid, scalable, and energy-efficient fabrication technique. In this regard, mechanochemical synthesis has gained significant attention as a promising approach. In this work, we demonstrate the applicability and the potential of mechanochemical synthesis for the preparation of p-type skutterudites using Yb0.75Ce0.25Fe3.5Co0.5Sb12 composition as an example. In fact, the time spent on a full cycle of synthesis of bulk samples is less than 10 h, and the highest figure of merit value was 0.62, which is comparable to the values for similar compositions from previously works, where the time for synthesis is tens of times longer.
Channel-facilitated transport under resetting dynamics
Authors: Pal Suvam , Boyer Denis , Dagdug Leonardo , Pal Arnab
Published: October 2024

The transport of particles through channels holds immense significance in physics, chemistry, and biological sciences. For instance, the motion of solutes through biological membranes is facilitated by specialized proteins that create water-filled channels. Valuable insights can be obtained by studying the transition paths of particles through a channel and gathering information on their lifetimes inside the channel as well as their exit probabilities. In a similar vein, we consider a one-dimensional model of channel-facilitated transport where a diffusive particle is subject to attractive interactions with the walls of the channel. We study the statistics of conditional and unconditional escape times in the presence of resetting—an intermittent dynamics that brings the particle back to its initial coordinate stochastically. We determine analytically the physical conditions under which such a resetting mechanism becomes beneficial for the faster escape of the particles from the channel, thus enhancing transport. Our theory has been verified with the aid of Brownian dynamics simulations for various interaction strengths and extents. The overall results presented herein highlight the scope of resetting-based strategies to be universally promising for complex transport processes of single or long molecules through biological membranes.
Interpreting the power spectral density of a fluctuating colloidal current
Authors: Knowles Stuart F. , Mackay Eleanor K. R. , Thorneywork Alice L.
Published: October 2024

The transport of molecules through biological and synthetic nanopores is governed by multiple stochastic processes that lead to noisy, fluctuating currents. Disentangling the characteristics of different noise-generating mechanisms is central to better understanding molecular transport at a fundamental level but is extremely challenging in molecular systems due to their complexity and relative experimental inaccessibility. Here, we construct a colloidal model microfluidic system for the experimental measurement of particle currents, where the governing physical properties are directly controllable and particle dynamics directly observable, unlike in the molecular case. Currents of hard spheres fluctuate due to the random arrival times of particles into the channel and the distribution of particle speeds within the channel, which results in characteristic scalings in the power spectral density. We rationalize these scalings by quantitatively comparing to a model for shot noise with a finite transit time, extended to include the distribution of particle speeds. Particle velocity distributions sensitively reflect the confining geometry, and we interpret and model these in terms of the underlying fluid flow profiles. Finally, we explore the extent to which details of these distributions govern the form of the resulting power spectral density, thereby establishing concrete links between the power spectral density and underlying mechanisms for this experimental system. This paves the way for establishing a more systematic understanding of the links between characteristics of transport fluctuations and underlying molecular mechanisms in driven systems such as nanopores.
Data-driven airfoil shape optimization framework for enhanced flutter performance
Authors: Jung Jiyoung , Gu Grace X.
Published: October 2024

This paper presents a machine learning-based airfoil shape optimization framework designed to increase flutter resistance and reduce drag. Using the National Advisory Committee for Aeronautics airfoil as the base design and a Hicks–Henne bump function, we employ multi-objective Bayesian optimization and harmonic balance-based flutter prediction. The optimization process yields a Pareto front revealing trade-off relationships between the flutter speed index and drag coefficient. The optimized airfoils, resembling those of evolved marine animals, outperform the base design in terms of flutter resistance and drag. These results demonstrate the framework's potential to enhance aircraft performance and safety by addressing aeroelastic factors.
Engineering of ferroelectricity in thin films using lattice chemistry: A perspective
Authors: Efe Ipek , Yan Bixin , Trassin Morgan
Published: October 2024

Ferroelectric materials hold significant potential for ultralow-energy-consuming oxide electronics and have recently been pointed out as a suitable platform for next-generation neuromorphic and reservoir computing schemes. We provide a brief overview of the progress in engineering electric dipole textures of epitaxial ferroelectric oxide thin films, with an emphasis on the technologically relevant ultrathin regime. In epitaxial films that are only a few unit-cells thick, surface chemistry and interfacial electrostatics are commonly considered limiting factors in ferroelectric device integration, as they may suppress the net ferroelectric behavior. Here, we highlight how nanoscale lattice chemistry control, including off-stoichiometry and layer polarization in oxides, can, in fact, emerge as powerful tools for engineering ferroelectricity in thin films. We also discuss the potential of such an approach in the context of recent trends in the field, such as the design of ferroelectric freestanding membranes and the optical control of polarization in thin films. Hence, with our Perspective article, we aim to provide key insights on the use of lattice chemistry for ferroelectricity engineering in thin films to facilitate exciting developments in ferroelectric-based applications.
Thermophysical and mechanical properties of multicomponent Zr37Hf16Ni12.5Cu12.5Al11Co6Nb5 bulk glass-forming alloy
Authors: Wu B. W. , Hu L. , Mi X. L. , Long Q. , Wan Z. X. , Wei B.
Published: October 2024

The Zr37Hf16Ni12.5Cu12.5Al11Co6Nb5 bulk metallic glass (BMG) with strong glass-forming ability (GFA) and remarkable mechanical properties was designed, and its thermophysical properties were characterized simultaneously. The glass transition temperature reached up to 726 K, while the fragility index of 43 was derived by measuring alloy viscosity. The undercooled liquid of this BMG with such a low fragility index displayed a strong liquid behavior, corresponding to its small crystallization driving force and high GFA. The thermal expansion coefficient increased from 9.76 × 10−6 K−1 of glassy state to 2.71 × 10−5 K−1 of undercooled liquid, and the close-packed structure was evidenced by the low specific energy for free volume formation of 239.4 kJ/mol. Owing to its low free volume and high glass transition temperature, this BMG exhibited remarkable tensile and compressive yield strengths up to 1660.3 and 2042.3 MPa, respectively.
Thermophysical properties of solid and liquid nickel near melting point
Authors: Galtsov I. S. , Fokin V. B. , Dorovatovsky A. V. , Paramonov M. A. , Demyanov G. S. , Minakov D. V. , Sheindlin M. A. , Levashov P. R.
Published: October 2024

Our study is devoted to the thermophysical properties of solid and liquid nickel in the vicinity of the melting point. For this purpose, we use a first-principles calculation method based on quantum molecular dynamics and experimental measurements with a pulse heating technique. We provide experimental and calculated data on thermal expansion, molar enthalpy, sound velocity, resistivity, and normal spectral emissivity and analyze them together with available experimental and reference data on solid and liquid Ni. We confirm experimentally and computationally the strong temperature dependence of Ni density observed in several experiments. Our fusion enthalpy measurements are in good agreement with the recommended literature data, and the calculation predicts a slightly smaller change in enthalpy. The experimental measurements of nickel resistivity in the solid and liquid states agree with previous experimental data that take into account its correction for thermal expansion. At the same time, our calculation of the resistivity in the solid phase shows a systematic shift. For liquid nickel, we report a weak nonlinear temperature dependence of the normal spectral emissivity. Thus, taking advantage of experimental and ab initio computational approaches, we present consistent data on the thermophysical properties of solid and liquid Ni.
Strain-induced ferroelectric phase transition and second-harmonic generation enhancement in NbOCl2 monolayer
Authors: Ding Yi-min , Huang Anqi , Wu Yu , Zhou Liujiang
Published: October 2024

Two-dimensional (2D) materials exhibiting both second-harmonic generation (SHG) and ferroelectric properties are promising candidates for high-performance optoelectronic devices. However, the relationship between SHG response and ferroelectric polarization and bandgap in such materials has not been revealed clearly. Therefore, by using first-principles calculations based on many-body theory, we comprehensively study the structural, electronic, linear and nonlinear (SHG) properties of ferroelectric NbOCl2 monolayer under strain regulation to clarify the influence of ferroelectric polarization (Ps) and bandgap on the SHG coefficient. Our results show a ferroelectric to nonpolar phase transition under compressive strain larger than 5% along the polar direction. Moreover, under strain, the electronic bandgap, optical gap Eo, and SHG coefficient can be modified to a large extent and show different variation tendencies before and after phase transition. Importantly, a volcano relationship between SHG coefficient and a combined parameter (β1 = Ps*Eo) is established. Our findings unambiguously demonstrates the correlation between structural distortion, spontaneous polarization, and SHG property and have important implications for developing ferroelectric and nonlinear optical devices.
Does the direct effect of friction increase continuously with absolute temperature?
Authors: Barbot Sylvain
Published: October 2024

Constitutive models of fault friction form the basis of physics-based simulations of seismic activity. A generally accepted framework for the slip-rate and state dependence of friction involves a thermally activated process, whereby the probability of slip along microasperities adheres to an Arrhenius law. This model, which has become widely adopted among experimentalists and theoreticians, predicts a continuous increase of the direct effect with absolute temperature, but is it observed experimentally? Leveraging comprehensive laboratory data across diverse hydrothermal, barometric, and lithological conditions, we demonstrate that, contrary to the classical view, the direct effect for a given deformation mechanism remains largely temperature-independent. Instead, the incremental shifts in the direct effect often coincide with the brittle to semi-brittle transition, across which distinct deformation mechanisms operate. These considerations challenge the validity of the classical model. Realistic constitutive laws for rock failure within the lithosphere must incorporate the contributions of multiple deformation mechanisms within active fault zones.
Brazilian Portuguese wh-clefts in a multilevel analytic perspective
Authors: Andrade Aroldo , Antonio Juliano Desiderato
Published: October 2024

This paper presents a study on the distribution of wh-clefts – i.e. those having a nominal phrase
in the cleft constituent position – in a corpus of TV interviews spoken in Brazilian Portuguese. This language variety has three
types of wh-clefts, dubbed canonical, reversed and extraposed, which are analyzed in three levels: the
informational-structural level, regarding the types of focus patterns; the macro-discursive level, on how these constructions
distribute into topical-chain segments; and the micro-discursive level, with special attention to the rhetorical relations
connecting wh-clefts to their immediate contexts. Nevertheless, only the two first levels are crucial for
assessing their distribution. We put forward that the results may be explained by the features [unexpectedness] and [topicality],
distributed hierarchically, since the first one forces a contextual question to become explicit, as canonical
wh-clefts are considered to embed a semi-rhetorical question. The conclusion is that the notion of ‘prominence’
can connect the various results.
“Why does he appear so ordinary, but he can be so confident”
Authors: Wang Jiayu , Zhao Yaru
Published: October 2024

Adopting proximization theory as its analytical framework, this article examines the feminist discourse of
controversial Chinese talk show performer Yang Li. Yang’s talk show is known for her incisive and sarcastically humorous remarks
on men, and her speeches have aroused widespread controversies. Our analysis finds that by positioning herself and other women as
the inside deictic-centers (IDCs) within her constructed discourse space, Yang tactically presents the spatial, temporal and
axiological proximization from the outside deictic-centers (ODCs) mainly composed of men. Yang’s version of the controversial
feminism has revealed gender inequality and conventional patriarchy in contemporary society; but the reliance on male- and
class-based gender stereotypes and the imagery projected from past incidents to create gendered or even men-hating discourses has
begot controversies and backlashes. This study also discusses how Yang’s controversial feminist discursive patterns are influenced
by the platformization of daily life, and the commodification and entertainmentization of gender issues against the backdrop of
contemporary Chinese society where neoliberalism, market, capital and convention coexist.
You have no right!
Authors: King Jeremy
Published: October 2024

The present study seeks to reconsider popular assumptions regarding the dynamics of power in interpersonal
interactions in light of data from an historical North American speech community. Specifically, I examine directive and commissive
speech act formulations in colonial Spanish Louisiana data, both in terms of the level of directness employed in their head acts
as well as the degree of tentativeness which accompanies them. The corpus for the study consists of 200 institutional letters
composed in two settlements of the Louisiana territory between 1778 and 1802. Study findings reveal that speakers in Spanish
Louisiana showed a clear preference for directly formulated speech acts, but that the level of tentativeness used in this period
was highly dependent on the relative power of the speaker in the interaction. The results thus call into question traditional
notions of the ‘rights’ speakers possess to issue certain types of speech acts.
Language mediation training and the foreign‑language effect in moral
decision‑making*
Authors: García Álvaro Marín
Published: October 2024

Moral cognition is an emerging field investigating the cognitive
underpinnings of moral judgement and moral decision-making. Of particular
interest for Cognitive Translation and Interpreting Studies (CTIS) is the impact
of the use of a foreign language on the cognitive processes associated with
moral decision making, what has been labeled “Foreign Language Effect” (FLE).
Using a second language has been reported to reduce decision-making biases,
doing away with framing effects in risk aversion settings. At the same time,
moral dilemmas posed in a second language prompt more utilitarian responses than
when presented in the subjects’ native tongues. These results beg the following
question for the CTIS scholar: does language mediation training mitigate the
FLE? This paper reports on an exploratory study investigating the impact of
language mediation training on the FLE. Drawing from Costa et al. (2014), 1st and 4th year, bilingual
students in a Translation and Interpreting degree are presented with the trolley
dilemma both in their L1, L2, and L3. Initial results seem to indicate that
language mediation training might have an impact on the FLE. However, the
limitations of the study suggest the need for further exploration of the
intersection between language mediation training and the FLE.
Psychometric properties of survey translations
Authors: Mellinger Christopher D. , Hanson Thomas A.
Published: October 2024

Psychometrics involves the indirect measurement of latent constructs, including aspects of cognition and emotion,
and Likert-type scales are a common tool to operationalize and quantify these constructs. One threat to the psychometric
properties of such scales is the administration of surveys across multiple languages, which presupposes the translation of the
survey instruments. While multiple recommendations exist on best practices in translation, implementation does not always satisfy
such guidelines. This article employs Monte Carlo simulation to explore the potential effects of translation on survey measurement
and psychometric properties. Three possible challenges are explored, namely ambiguity, shift in valence, and issues with negation.
These translation effects are statistically modeled as increased variance, change in skewness, and reverse coding, respectively.
Additionally, the simulation examines the value of multi-item scales over single-item measurement. Overall, the results illustrate
how survey translation can impact exploratory factor analysis and reliability of measurement.
Multimodal exploration of the thank God expressive
construction and its implications for translation
Authors: Martínez Fernando Casanova
Published: October 2024

Multimodal research in communication and translation studies is
increasingly recognized, yet it remains incompletely explored. Leveraging
computational linguistics with both Praat for acoustic analysis and the OpenPose
and Rapid Annotator tools for visual analysis, this study delves into the
intricate dynamics of the expressive construction thank God,
providing a comprehensive examination of both visual and acoustic dimensions.
Our objective is to uncover nuanced patterns of multimodal communication
embedded within this expression and their implications for Translation and
Interpreting. Through an analysis of linguistic features and co-speech gestures
present in thank God, we aim to deepen our comprehension of how
meaning crisscrosses modalities. Our findings underscore the necessity of a
multimodal approach in language studies, emphasizing the requisite to preserve
emotional and contextual nuances. The analysis unveils the phonological
relevance of the duration of the construction’s second vowel, a key factor for
translation. Additionally, data reveals a correlation between the emotion of
relief and gestures executed with both hands closer to the chest. Overall, these
findings contribute to advancing both multimodal communication research and
translation studies, shedding light on the role of multimodal analysis in
understanding language and translation dynamics, particularly in the context of
constructions like thank God.
Microscopic Theory of Nonlinear Hall Effect in Three-Dimensional Magnetic Systems
Authors: Hou 侯 Wen-Tao 文涛 , Zang 臧 Jiadong 佳栋
Published: October 2024

Nonlinear Hall effect (NLHE) has been detected in various of condensed matter systems. Unlike linear Hall effect, NLHE may exist in physical systems with broken inversion symmetry in crystals. On the other hand, real space spin texture may also break inversion symmetry and result in NLHE. We employ the Feynman diagrammatic technique to calculate non-linear Hall conductivity (NLHC) in three-dimensional magnetic systems. The results connect NLHE with the physical quantity of emergent electrodynamics which originates from the magnetic texture. The leading order contribution of NLHC, χabb
, is proportional to the emergent toroidal moment

T
a
e

, which reflects how the spin textures wind in three dimensions.
On the nonequilibrium dynamics of gravitational algebras
Authors: Cirafici Michele
Published: October 2024

We explore nonequilibrium features of certain operator algebras which appear in quantum gravity. The algebra of observables in a black hole background is a TypeII∞von Neumann algebra. We discuss how this algebra can be coupled to the algebra of observable of an infinite reservoir within the canonical ensemble, aiming to induce nonequilibrium dynamics. The resulting dynamics can lead the system towards a nonequilibrium steady state which can be characterized through modular theory. Within this framework we address the definition of entropy production and its relationship to relative entropy, alongside exploring other applications.
Electromagnetic Debye mass within Gribov–Zwanziger action
Authors: Bandyopadhyay Aritra
Published: October 2024

In the present study we have investigated the electromagnetic Debye mass by computing the static limit of the temporal component of the one-loop photon polarization tensor involving effective quarks in the loop. These effective quarks have been considered within the Gribov–Zwanziger action, thereby incorporating the necessary non-perturbative effects. As an academic exercise, we have also shown one of the applications of this Gribov modified Debye mass by using it to evaluate the real and imaginary parts of the heavy quark potential in a Quantum Electrodynamics (QED) system. This computation of the electromagnetic Debye mass and the corresponding estimations of the heavy quark potential can be seen as stepping stones in the direction of further practical Quantum Chromodynamics (QCD) calculations in the non perturbative domain.
Heat transfer origin of adhesion behaviors between liquid-aluminum and solid aluminum/silicon interfaces
Authors: Dong Yun , Hui Weibin , Ding Yusong , Lian Fangming , Yan Lianjia
Published: October 2024

Liquid-aluminum tends to adhere to some surfaces rather than others, and the underlying mechanism of the differences in adhesion of liquid-aluminum on different surfaces is still unclear. This manuscript takes liquid-aluminum/aluminum and liquid-aluminum/silicon interfaces as research objects, revealing that solid aluminum surface is aluminophilic but the solid silicon surface is aluminophobic, mainly due to differences in interfacial thermal conductance (ITC) between two interfaces. We also investigate effect of surface temperature on adhesion characteristics of liquid-aluminum on aluminum/silicon surfaces, and decode the reasons from lattice integrity and phonon spectra. It is shown that vibrational state with intact lattice excites fewer low frequency phonons with increasing surface temperature, resulting in a decrease in ITC and thus adhesion force. In diffusion state where lattice is fractured resulting from high temperature, interfacial adhesion is increased due to surface defects.
Aggregation-induced emissive copper nanoclusters with peroxidase-like activity for colorimetric detection of cholesterol
Authors: Wang Yang , Wang Wei , Fang Yuan , Tao Dengwu , Tang Kaiyan , Nie Jinshan , Chang Baisong
Published: October 2024

Accurate and point-of-care cholesterol detection is of paramount significance for the prevention of cardiovascular diseases. The colorimetric assay based on peroxidase is a commonly used approach for cholesterol detection, without requiring any complicated biomolecular labeling or sophisticated instrumentation. Copper nanoclusters (CuNCs), exhibiting luminescent properties and peroxidase activity, have garnered significant attention in biomedical application recently. Herein, the glutathione-stabilized copper nanoclusters (GSH-CuNCs) were prepared with an easy one-pot method, employing glutathione as both a reducing agent and stabilizer. An optimization of the GSH-CuNCs preparation was carried out to obtain the highest peroxidase-like activity. UV-Vis absorption was measured to explore the steady-state kinetics of the GSH-CuNCs-catalyzed oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) by H2O2. A colorimetric method for cholesterol detection was developed by combining the catalytic reaction of CuNCs and the enzymatic oxidation of cholesterol with cholesterol oxidase (ChOx). Under the optimized conditions, the UV-Vis absorbance of oxidized TMB (oxTMB) is proportional to the concentration of cholesterol within the range of 6.2–187.5 μM, and the limit of detection (LOD) is determined to be 3.0 μM. More importantly, cholesterol levels can be directly distinguished with the naked eye. Furthermore, the practicality of the method for detecting cholesterol in human serum has been verified with promising results. As expected, this simple, cost-effective, and easy-to-operate colorimetric method for cholesterol detection has potential applications in clinical diagnosis and provides valuable insights into the colorimetric sensing based on CuNCs.
Effect of discontinuous harvesting on a diffusive predator-prey model
Authors: Zhang Xuebing , Li Shunjie , Yuan Yuan , An Qi
Published: October 2024

The management of predator-prey systems, particularly those with discontinuous harvesting, plays a crucial role in maintaining ecological balance and ensuring the sustainable use of renewable resources. Despite the importance of this topic, the dynamics of diffusive predator-prey models with discontinuous harvesting have not been thoroughly explored in existing literature. This study addresses this gap by investigating a diffusive predator–prey model incorporating a discontinuous harvesting function. We establish the existence and boundedness of solutions, analyse the conditions under which a positive steady state is achieved, and explore the model’s stability, including global asymptotic stability and convergence in finite time. Additionally, we examine the effects of Turing instability, Hopf bifurcation, and steady-state bifurcation within the model. Numerical simulations are provided to illustrate the impact of discontinuous harvesting on the system’s dynamics, highlighting the practical applications of the theoretical results in fields such as pest control. The findings of this study offer valuable insights for the design of effective population management strategies in ecological and agricultural contexts.
Effect of thermal shock on energy density of biaxially oriented polypropylene films for pulsed power capacitors
Authors: Chen Ke , Du B X , Liu Haoliang , Xiao Meng
Published: October 2024

In this paper, thermal shock experiments are performed on the biaxially oriented polypropylene (BOPP) films, and the changes in dielectric and energy storage properties before and after the experiments are explored. The experimental results show that the films have reduced comprehensive performance with the thermal shock time and frequency increasing. After the thermal shock, both the permittivity and the dielectric loss increase slightly. And, the direct current (DC) conductivity has risen by 73.6%–714.2%. The lowest DC breakdown strength of film is 604.4 kV mm−1, showing a 13.5% reduction compared to that of pristine film. In addition, energy storage performance has also deteriorated. The maximum discharge energy density decreased from 4.62 J cm−3 of pristine film to 3.26 J cm−3 of treated film. There is a decrease in charge and discharge efficiency under the same electric field. The metallization layer of the film receives less influence; the capacitance is reduced by only 0.37%. The causes and mechanisms of performance changes are analyzed and discussed. The disruption of molecular chains during thermal shock is the most important factor leading to the degradation of films. This paper provides a powerful perspective and reference for studying the performance degradation and failure of polymer dielectrics under extreme operating conditions.
Investigating zero-point vibrations of solid hydrogen via statistical moment method
Authors: Tam Nguyen Trong , Hoang Hai , Lam Le Thu , Hieu Ho Khac
Published: October 2024

Zero-point vibrations of solid hydrogen are investigated by analyzing the molecular mean-squared displacement (MSD) and mean-squared relative displacement functions within the statistical moment method approach in statistical mechanics. Numerical computations of these thermodynamic properties were conducted for solid hydrogen from 0 K to its phase transition temperature using the Wigner-Kirkwood mean-field potential derived from the Buckingham exp-6 potential. We have shown that the quantum-mechanical zero-point vibrations play an important role at low temperature. And these thermodynamic quantities increase with temperature, suggesting that both thermal and quantum effects play a significant role near the liquid-solid phase transition. The favorable consistency between our findings and the recent experimental inelastic neutron scattering measurements of MSD attests to the potential of SMM as a novel approach for determining the atomic vibrations of solid hydrogen. This approach allows us to study these effects including the anharmonicity of lattice vibrations.
The First Palomar Gattini-IR Catalog of J-band Light Curves: Construction and Public Data Release
Authors: Murakawa Shion , De Kishalay , Ashley Michael C. B. , Earley Nicholas , Hillenbrand Lynne A. , Kasliwal Mansi M. , Lau Ryan M. , Moore Anna M. , Sokoloski J. L. , Soria Roberto
Published: October 2024

Palomar Gattini-IR (PGIR) is a wide-field, synoptic infrared time domain survey covering ≈15,000 sq. deg. of the accessible sky at ≈1–3 night cadence to a depth of J ≈ 13.0 and ≈14.9 Vega mag in and outside the Galactic plane, respectively. Here, we present the first data release of J-band light curves of Two Micron All Sky Survey (2MASS) sources within the survey footprint covering approximately the first four years of operations. We describe the construction of the source catalog based on 2MASS point sources, followed by exposure filtering criteria and forced PSF photometry. The catalog contains light curves of ≈286 million unique sources with 2MASS magnitudes of J < 15.5 mag, with a total of ≈50 billion photometric measurements and ≈20 billion individual source detections at signal-to-noise-ratio > 3. We demonstrate the photometric fidelity of the catalog by (i) quantifying the magnitude-dependent accuracy and uncertainty of the photometry with respect to 2MASS and (ii) comparing against forced PGIR aperture photometry for known variable sources. We present simple filtering criteria for selecting reliable photometric measurements as well as example Python notebooks for users. This catalog is one of the largest compilation of nightly cadence, synoptic infrared light curves to date, comparable to those in the largest optical surveys, providing a stepping stone to upcoming infrared surveys in the coming decade.
The optimization of the hinge point position with a 2-DOF planar parallel heavy-duty hoisting mechanism
Authors: Tan Jie , Liu Yuhong , Li Weiming , Wu Daqi , Xue Yuan
Published: October 2024

By analyzing the mechanic’s characteristics of the hydraulic cylinder of the moving arm of the lifting mechanism under several extreme working conditions, the mathematical model of optimizing the hinged position of the lifting mechanism is established with the minimum and maximum load of the hydraulic cylinder of the moving arm as the optimization objective. The problem of multi-objective optimization is dealt with by the method of extremely large and extremely small and solved by the optimization algorithm. Through optimization, the maximum force of the hydraulic cylinders can be markedly reduced, the force characteristics of the lifting mechanism can be improved, and the ultimate load at the hinge point of each hydraulic cylinder can be reduced. The optimization method provides an important basis for the parameter design and improvement of the lifting mechanism and similar products.
Research on multi-parameter optimization technology of spiral bevel gear blank
Authors: Tan Yuxin , Zhang Aiqiang , Chen Siyu , Chen Shilin , Wei Jing , Shu Ruizhi
Published: October 2024

Aiming at the harsh working conditions of aviation bevel gears and the cumbersome design process of traditional tooth blank parameters and other issues, this paper firstly compared the differences between the standards results of the International Organization Standard (ISO) and American Gear Manufacture Association (AGMA) and finds that the calculation of the ISO standard was more instructive. The calculation resulted in the larger module, and the more teeth had a higher load-carrying capacity, which was more suitable for the design of bevel gears for aviation. Then, the ISO standard was used as the strength constraint to propose a multi-parameter optimization technique for bevel gear blanks. Based on the genetic algorithm, with fatigue strength and working condition requirements as double constraints, the design parameters of gear blanks, such as the number of teeth, module, and tooth width, were quickly screened out, which simplified the traditional design process of tooth blank parameters. The final optimization results effectively improved the designed gear’s strength and reduced the gear pair’s volume.
Optimized design of hydraulic and control system for longitudinal beam CNC bending machine
Authors: Wang Zhenbing , Hu Yong , Cao Kexin , Xu Mingxu , Hu Ye , Sun Shuhua
Published: October 2024

There is a certain gap between domestic and foreign countries in the processing accuracy and processing efficiency of longitudinal-beam bending machines, and the intelligence level of the factory is low. In this paper, the hydraulic system and control system of the CNC bending machine are optimized. The PID control algorithm with static compensation is used to effectively avoid the system instability caused by the dead-zone characteristics of the proportional valve. The bending test is carried out, and the test results show that the bending accuracy of the optimized control system can reach ±0.3mm, the production efficiency is increased by more than 30%, and the intelligence level of the factory is improved.
Simulation analysis and optimization of triple quadrupole mass spectrometer based on CFD
Authors: Huang Dong , Yin Shugui , Mao Luyao , Chen Qiyu , Mo Ting
Published: October 2024

CFD software conducted a hydrothermal simulation study of a triple quadrupole mass spectrometer. The results show that the auxiliary intake fan has a poor effect on cooling the PCB circuit board inside the mass spectrometer, but instead generates a vortex here, affecting the stability of the instrument. Besides, the reinforcing ribs on the bottom plate of the mass spectrometer and the orifice plate in the PCB slot prevent the flow of cooling air, resulting in high flow resistance and low cooling air volume. Therefore, structural optimization was carried out on the bottom plate and orifice plate of the mass spectrometer. The results show that after optimization, the air volume of the main intake fan increased by 6.2%, the air volume entering the PCB slot increased by 29.9%, and its proportion to the air volume of the main intake fan increased by 22.2%. The average temperature of the RF amplification board decreased by 17.3%, resulting in a better cooling effect. Meanwhile, simulation and comparison of the two installation positions of the dustproof cotton showed that installing the dustproof cotton around the bottom plate had a better effect.
Numerical simulation of thermal deformation of oil distribution sleeve based on heat transfer theory
Authors: Lei Fengli
Published: October 2024

In this paper, a study of numerical simulation was conducted based on heat transfer and finite element theory, to analyze the sealing gap change between the oil distribution sleeve (ODS) and the shaft by the effect of temperature. The results showed that the temperature is the dominant reason for the failure of the ODS seal. The thermal deformation of the ODS is radiative expansion and the sealing gap is linearly positively related to the temperature. The wall thickness did not affect the distribution of thermal deformation of the ODS. The sealing gap increases with the increase of the thickness of the inner cylinder but decreases with the increase of the thickness of the outer cylinder. Therefore, keeping a small thickness ratio is conducive to enhancing the sealing performance of the ODS.
Application of multiple spectrum domain fault probability fusion model in high-speed rail bearings
Authors: Gong Baogui , Zhang Xingwu , Chen Xuefeng
Published: October 2024

High-speed railway bearings are one of the core transmission components of high-speed railway multiple units, and their degraded performance can directly affect the safety performance of vehicles. How to identify faults in high-speed rail bearings and represent them in data has always been an industry challenge. To this end, multiple frequency domain fault probability fusion models have been proposed for research. The first choice for this model is to provide an analysis method for converting the frequency domain spectrum to fault probability. Subsequently, five frequency domain spectrum analysis methods that are easy to detect bearing faults were selected, and all of them were converted into fault probability. Finally, based on D-S evidence theory, fusion was carried out to obtain multiple frequency domain fault probability fusion models, achieving efficient identification and data representation of high-speed railway bearing faults. Finally, the effectiveness of the model was verified through fault simulation experiments.
Effect of hydraulic oil temperature on the flow output quality of external gear pump
Authors: Li Mingxue , Wu Tao , Wen Run , Chen Wanlong
Published: October 2024

To investigate the impact of hydraulic oil temperature on the performance of an external gear pump, we developed a numerical model to simulate the internal flow field of the pump. Utilizing Computational Fluid Dynamics (CFD) techniques and the full cavitation model, we conducted an analysis on how varying hydraulic oil temperatures affect the pump’s flow quality. Through dynamic numerical simulations, we examined the relationship between hydraulic oil temperature and the flow quality of the gear pump. The findings indicated that the gear pump exhibits optimal flow performance when the hydraulic oil temperature is maintained within a suitable range. Should the temperature deviate from this optimal range, the cavitation within the pump’s flow field intensifies, leading to a decline in the overall flow quality of the gear pump, which worsens with the extent of the temperature deviation.
Simulation and experimental study of heat pump air-side heat transfer
Authors: Bie Yufeng , Zheng Zhu , Yan Zhen , Chen Yunfei
Published: October 2024

A simulation model is developed for the air side of a heat pump dryer which defines the smallest heat exchange unit between fins and air, focusing on the heat exchange between them. A self-constructed test bench was designed to control the temperature and humidity inlet of the heat pump and minimize the impact of environmental factors. The study examined the impact of diverse inlet conditions on heat pump heat transfer performance via a test bench. The experimental results were compared to the simulation outcomes to verify the precision of the model, which recorded a 3.31% outlet temperature deviation. Furthermore, the analysis discovered that the link between the outlet temperature and the inlet air volume of the heat pump demonstrates distinct stage features. When the airflow is below 170 m3/h or above 230 m3/h, the temperature of the heat pump outlet remains almost constant. However, when the airflow falls between 170 m3/h and 230 m3/h, the heat pump outlet temperature becomes dependent on the heat pump’s operational power. The simulation of the unit model under constant temperature boundary conditions and constant heat flow boundary conditions models the variation of outlet temperature and airflow. This model facilitates the thermal design of the heat pump system, particularly for the examination of heat transfer properties under varying inlet conditions. Furthermore, it ensures the validation of the effectiveness of numerical simulation methods in evaluating and enhancing air-side heat transfer in heat pumps for different engineering applications.
Decadent Appropriation
Authors: Macpherson Ben
Published: October 2024

The second chapter of Singing Utopia develops a new way of thinking about the complex plurality of vocal styles evident in musical theatre. From the classical sound of early musical comedy to the pop and hip hop aesthetic of contemporary performances, the chapter examines changing tastes, expectations, and performance practices at play in what it calls the ‘voiceworlds’ of musical theatre. Drawing on literary theory, voice studies, cultural analysis, and musicology, the chapter further develops the concept of ‘decadent appropriation’ as a new way of analysing what is heard in these voiceworlds. Identifying discrete vocal styles along with the processes and consequences of their appropriation, the chapter listens across five case studies. The first part of the chapter listens to Florodora (1899), The Phantom of the Opera (1986), and Floyd Collins (1996), recasting the ideology of operatic vocality in the same vocal space as music hall patter, pop voice, and folk singing. The chapter then listens to more popular styles including crooning, belt, and rock voice in Guys and Dolls (1950) and Passing Strange (2008), further discovering a decadence which is political and subversive, with a particular focus on the difficult relationships between race, politics, society, and personal identity in the act of singing utopia.
Intermediate Vocalities
Authors: Macpherson Ben
Published: October 2024

This chapter explores what happens when individual characters and entire communities inhabit aural spaces somewhere between speech and song. Employing an analytical method from ethnography, the utopian potentials of these ‘intermediate’ vocalities are examined in four case studies. First, listening to the conman’s patter of Professor Harold Hill (The Music Man, 1957) and the Jewish inflections of Fagin’s speak-singing (Oliver! 1960), the chapter considers what is revealed about the relationship between individuals on the outside of communities and the potential for utopia. The chapter then listens to the hesitant vocality of townsfolk of Into the Woods (1987) and the political imperatives of hip hop and rap in Hamilton (2015), considering what happens when entire voiceworlds resist the utopian vocality of song—and what it means when they succumb.
Introduction
Authors: McKenna Michael
Published: October 2024

What is the relationship between desert and moral responsibility? The most immediate answer is that desert supplies a distinctive normative basis for holding wrongdoers morally responsible. But this tells us little unless we gain some sense of the nature of these responses—what such things as blame and punishment are—as well as the nature of the normativity distinctive of desert. The conversational theory of moral responsibility explains our responses of blame and punishment on analogy with a meaningful reply to another in a conversation. Desert in turn offers a normative basis for these responses insofar as they are harmful. With an initial characterization of the relation between the conversational theory and desert, this chapter then offers a brief description of the ground covered in the pages to follow.