bluuebunny/crossref_metadata_2025 huggingface dataset:
Stability of oblique liquid curtains with surface tension
Authors: Benilov E. S.
Published: March 2023

Oblique (non-vertical) liquid curtains are examined under the assumption that the Froude number is large. As shown previously [E. S. Benilov, “Oblique liquid curtains with a large Froude number,” J. Fluid Mech. 861, 328 (2019)], their structure depends on the Weber number: if We < 1 (strong surface tension), the Navier–Stokes equations admit asymptotic solutions describing curtains bending upward, i.e., against gravity. In the present paper, it is shown that such curtains are unstable with respect to small perturbations of the flow parameters at the outlet: they give rise to a disturbance traveling downstream and becoming singular near the curtain's terminal point (where the liquid runs out of the initial supply of kinetic energy). It is argued that, since the instability is spatially localized, the curtain can be stabilized by a properly positioned collection nozzle. All curtains with We > 1 bend downward and are shown to be stable.
On the challenge of sampling multiple nucleation pathways: A case study of heterogeneous ice nucleation on FCC (211) surface
Authors: Zhao Wanyu , Li Tianshu
Published: March 2023

Heterogeneous ice nucleation is ubiquitous but its microscopic mechanisms can be extraordinarily complex even on a simple surface. Such complexity poses a challenge in modeling nucleation using advanced sampling methods. Here, we investigate heterogeneous ice nucleation on an FCC (211) surface by a forward flux sampling (FFS) method to understand how the complexity in nucleation pathways affects the accuracy of FFS. We first show the commonly adopted, size-based order parameter fails to describe heterogeneous ice nucleation on the FCC (211) surface. Inclusion of geometric anisotropy of ice nucleus as an additional descriptor is found to significantly improve the quality of the size-based order parameter for the current system. Subsequent application of this new order parameter in FFS identifies two competing ice nucleation pathways in the system: a primary-prism-planed (PPP) path and a secondary-prism-planed (SPP) path, both leading to the formation of hexagonal ice but with different crystalline orientations. Although the PPP pathway dominates ice nucleation on the FCC (211) surface, the occurrence of the less efficient SPP pathway, particularly its strong presence at the early stage of FFS, is found to yield a significant statistical uncertainty in the calculated FFS rate constant. We develop a two-path model that enables gaining a general, quantitative understanding of the impact of initial finite sampling on the reliability of FFS calculations in the presence of multiple nucleation pathways. Our study also suggests a few general strategies for improving the accuracy of FFS when exploring unknown but complex systems.
Community health workers (Behvarz) in primary health care: a qualitative inductive content analysis of challenges
Authors: Shams Lida , Zamani Fard Maryam , Nasiri Taha , Mohammadshahi Marita
Published: March 2023

Background Behvarzs are the backbone of primary healthcare services in the Iranian health system and play a key role in providing efficient, responsive, and equitable services at the first level of service provision. This study aimed to identify the challenges of Behvarzs to provide a perspective for policymakers and managers to help them formulate future programs to enhance the efficiency of the health system. Methods Following a qualitative design, an inductive content analysis approach was used to analyse the data. The healthcare network of the Alborz province (Iran) was considered as the study context. A total of 27 interviews were conducted with policymakers, development managers, managers of Behavrz training centres, and Behvarz workers in 2020. All interviews were audio-taped and transcribed, followed by data analysis using MAXQDA ver. 10. Results Five themes were identified: service provision (scope of services, ambiguity of roles, non-compliance with the referral system, the quality of data entry, quality of services), access to equipment (quantity, quality), administrative issues (macro planning, micro planning), training (appropriateness of information, quality of training, recruiting related staff), perceived equity and fairness (balance between workload, income, and benefits, job satisfaction, job promotion). Conclusion Occupational challenges affect the performance of Behvarzs in responding to society’s needs because they not only play a major role in the health system, but also contribute to addressing the communication gap between local communities and high-level institutions, leading to the alignment of policy implementation. Therefore, strategies that emphasise the role of Behvarzs should be followed to promote community engagement.
Examining the influence of mid-tropospheric conditions and surface wind changes on extremely large fires and fire growth days
Authors: Potter Brian E.
Published: March 2023

Background Previous work by the author and others has examined weather associated with growth of exceptionally large fires (‘Fires of Unusual Size’, or FOUS), looking at three of four factors associated with critical fire weather patterns: antecedent drying, high wind and low humidity. However, the authors did not examine atmospheric stability, the fourth factor. Aims This study examined the relationships of mid-tropospheric stability and dryness used in the Haines Index, and changes in surface wind speed or direction, to growth of FOUS. Methods Weather measures were paired with daily growth measures for FOUS, and for merely ‘large’ fires paired with each FOUS. Distributions of weather and growth were compared between the two fire sets graphically and statistically to determine which, if any, weather properties correspond to greater growth on FOUS than on large fires. Key results None of the factors showed a robust difference in fire growth response between FOUS and large fires. Conclusions The examined measures, chosen for their anecdotal or assumed association with increased fire growth, showed no indication of that association. Implications Focus on wind changes and mid-tropospheric properties may be counterproductive or distracting when one is concerned about major growth events on very large fires.
Meeting the challenges of large-scale carbon storage and hydrogen production
Authors: Zoback Mark , Smit Dirk
Published: March 2023

There is a pressing need to rapidly, and massively, scale up negative carbon strategies such as carbon capture and storage (CCS). At the same time, large-scale CCS can enable ramp-up of large-scale hydrogen production, a key component of decarbonized energy systems. We argue here that the safest, and most practical strategy for dramatically increasing CO
2
storage in the subsurface is to focus on regions where there are multiple partially depleted oil and gas reservoirs. Many of these reservoirs have adequate storage capacity, are geologically and hydrodynamically well understood and are less prone to injection-induced seismicity than saline aquifers. Once a CO
2
storage facility is up and running, it can be used to store CO
2
from multiple sources. Integration of CCS with hydrogen production appears to be an economically viable strategy for dramatically reducing greenhouse gas emissions over the next decade, particularly in oil- and gas-producing countries where there are numerous depleted reservoirs that are potentially suitable for large-scale carbon storage.
SIK3–HDAC4 in the suprachiasmatic nucleus regulates the timing of arousal at the dark onset and circadian period in mice
Authors: Asano Fuyuki , Kim Staci J. , Fujiyama Tomoyuki , Miyoshi Chika , Hotta-Hirashima Noriko , Asama Nodoka , Iwasaki Kanako , Kakizaki Miyo , Mizuno Seiya , Mieda Michihiro , Sugiyama Fumihiro , Takahashi Satoru , Shi Shoi , Hirano Arisa , Funato Hiromasa , Yanagisawa Masashi
Published: March 2023

Mammals exhibit circadian cycles of sleep and wakefulness under the control of the suprachiasmatic nucleus (SCN), such as the strong arousal phase-locked to the beginning of the dark phase in laboratory mice. Here, we demonstrate that salt-inducible kinase 3 (SIK3) deficiency in gamma-aminobutyric acid (GABA)-ergic neurons or neuromedin S (NMS)–producing neurons delayed the arousal peak phase and lengthened the behavioral circadian cycle under both 12-h light:12-h dark condition (LD) and constant dark condition (DD) without changing daily sleep amounts. In contrast, the induction of a gain-of-function mutant allele of
Sik3
in GABAergic neurons exhibited advanced activity onset and a shorter circadian period. Loss of SIK3 in arginine vasopressin (AVP)–producing neurons lengthened the circadian cycle, but the arousal peak phase was similar to that in control mice. Heterozygous deficiency of histone deacetylase (HDAC) 4, a SIK3 substrate, shortened the circadian cycle, whereas mice with HDAC4 S245A, which is resistant to phosphorylation by SIK3, delayed the arousal peak phase. Phase-delayed core clock gene expressions were detected in the liver of mice lacking SIK3 in GABAergic neurons. These results suggest that the SIK3–HDAC4 pathway regulates the circadian period length and the timing of arousal through NMS-positive neurons in the SCN.
HIV post-treatment controllers have distinct immunological and virological features
Authors: Etemad Behzad , Sun Xiaoming , Li Yijia , Melberg Meghan , Moisi Daniela , Gottlieb Rachel , Ahmed Hayat , Aga Evgenia , Bosch Ronald J. , Acosta Edward P. , Yuki Yuko , Martin Maureen P. , Carrington Mary , Gandhi Rajesh T. , Jacobson Jeffrey M. , Volberding Paul , Connick Elizabeth , Mitsuyasu Ronald , Frank Ian , Saag Michael , Eron Joseph J. , Skiest Daniel , Margolis David M. , Havlir Diane , Schooley Robert T. , Lederman Michael M. , Yu Xu G. , Li Jonathan Z.
Published: March 2023

HIV post-treatment controllers (PTCs) are rare individuals who maintain low levels of viremia after stopping antiretroviral therapy (ART). Understanding the mechanisms of HIV post-treatment control will inform development of strategies aiming at achieving HIV functional cure. In this study, we evaluated 22 PTCs from 8 AIDS Clinical Trials Group (ACTG) analytical treatment interruption (ATI) studies who maintained viral loads ≤400 copies/mL for ≥24 wk. There were no significant differences in demographics or frequency of protective and susceptible human leukocyte antigen (HLA) alleles between PTCs and post-treatment noncontrollers (NCs, n = 37). Unlike NCs, PTCs demonstrated a stable HIV reservoir measured by cell-associated RNA (CA-RNA) and intact proviral DNA assay (IPDA) during analytical treatment interruption (ATI). Immunologically, PTCs demonstrated significantly lower CD4
+
and CD8
+
T cell activation, lower CD4
+
T cell exhaustion, and more robust Gag-specific CD4
+
T cell responses and natural killer (NK) cell responses. Sparse partial least squares discriminant analysis (sPLS-DA) identified a set of features enriched in PTCs, including a higher CD4
+
T cell% and CD4
+
/CD8
+
ratio, more functional NK cells, and a lower CD4
+
T cell exhaustion level. These results provide insights into the key viral reservoir features and immunological profiles for HIV PTCs and have implications for future studies evaluating interventions to achieve an HIV functional cure.
Dative alternation in Chinese
Authors: Zhang Dong , Xu Jiajin
Published: March 2023

This study investigates the factors significantly constraining dative alternation in Chinese by adopting mixed-effects logistic regression modelling. The analysis showed that such factors significantly affected the choice of dative variants in Chinese, including the animacy, pronominality, and definiteness of the recipient, the accessibility and concreteness of the theme, and the length difference between the theme and the recipient. Findings were compared with those for the English dative alternation discussed in the literature. When the theme was recoverable from context or shorter than the recipient, the prepositional dative construction was preferred in both English and Chinese. This can be explained by the principles of end-focus and end-weight. However, when the recipient was animate or definite, the double object construction was preferred in English, while the prepositional dative construction was more likely to be used in Chinese. This divergence is due to the different syntactic and semantic features of their recipient markers.
Measuring the visual in audio-visual input
Authors: Pujadas Geòrgia , Muñoz Carmen
Published: March 2023

This exploratory study investigates the effects of imagery on word learning through audio-visual input. A total of 82 adolescent EFL learners were exposed to 8 episodes of a TV series under four conditions, depending on the language of the on-screen text (L1 or L2) and whether they were pre-taught target words or not. The effects of co-occurrence of the word with its image, and the image time on screen (ITOS) were explored, alongside frequency, proficiency, and learning condition variables. Results showed that both image-related variables and frequency predicted word-form learning, while only ITOS predicted word-meaning recall, with a longer exposure to image associated to higher gains, suggesting that, at this age and proficiency level, the images associated with the words can be conducive to learning.
German and Romance civility in contact
Authors: Gennies Linda
Published: March 2023

In this paper, I argue for a systematic study of the role that language contact has played in the development of German, French, Italian and Spanish address systems. While the current state of research clearly points to contact-induced changes in Early Modern European polite address, some important desiderata concerning the precise direction, nature and scope of contact influences remain. Against this background, I present historical foreign language manuals as a promising source for the comparative study of historical European address practices and their development. Through an explorative analysis of metapragmatic comments and model dialogues in selected foreign language manuals, the increasingly dynamic pressures experienced by interlocutors both to distance themselves from one another and to express solidarity come to light, as multi-level address systems emerge and mixed styles of address gain in importance.
Extension of Linear Response Regime in Weak-Value Amplification Technique
Authors: Zhang Manchao , Zhang Jie , Su Wenbo , Yang Xueying , Wu Chunwang , Xie Yi , Wu Wei , Chen Pingxing
Published: March 2023

The achievable precision of parameter estimation plays a significant role in evaluating a strategy of metrology. In practice, one may employ approximations in a theoretical model development for simplicity, which, however, will cause systematic error and lead to a loss of precision. We derive the error of maximum likelihood estimation in the weak-value amplification technique where the linear approximation of the coupling parameter is used. We show that this error is positively related to the coupling strength and can be effectively suppressed by improving the Fisher information. Considering the roles played by weak values and initial meter states in the weak-value amplification, we also point out that the estimation error can be decreased by several orders of magnitude by averaging the estimations resulted from different initial meter states or weak values. These results are finally illustrated in a numerical example where an extended linear response regime to the parameter is observed.
Electronic Instability of Kagome Metal CsV3Sb5 in the 2 × 2 × 2 Charge Density Wave State
Authors: Zhu Hongen , Li Tongrui , Yu Fanghang , Li Yuliang , Wang Sheng , Wu Yunbo , Liu Zhanfeng , Shang Zhengming , Cui Shengtao , Liu Yi , Zhang Guobin , Zhang Lidong , Wang Zhenyu , Wu Tao , Ying Jianjun , Chen Xianhui , Sun Zhe
Published: March 2023

Recently discovered kagome metals AV3Sb5 (A = K, Rb, and Cs) provide an ideal platform to study the correlation among nontrivial band topology, unconventional charge density wave (CDW), and superconductivity. The evolution of electronic structures associated with the change of lattice modulations is crucial for understanding of the CDW mechanism, with the combination of angle-resolved photoemission spectroscopy (ARPES) measurements and density functional theory calculations, we investigate how band dispersions change with the increase of lattice distortions. In particular, we focus on the electronic states around

M
¯

point, where the van Hove singularities are expected to play crucial roles in the CDW transition. Previous ARPES studies reported a spectral weight splitting of the van Hove singularity around

M
¯

point, which is associated with the 3D lattice modulations. Our studies reveal that this “splitting” can be connected to the two van Hove singularities at kz
= 0 and kz
= π/c in the normal states. When the electronic system enters into the CDW state, both van Hove singularities move down. Such novel properties are important for understanding of the CDW transition.
Opportunities for new physics searches with heavy ions at colliders
Authors: d’Enterria David , Drewes Marco , Giammanco Andrea , Hajer Jan , Bratkovskaya Elena , Bruce Roderik , Burmasov Nazar , Dyndal Mateusz , Gould Oliver , Grabowska-Bold Iwona , Gumberidze Malgorzata , Gunji Taku , Holzmann Romain , Jowett John M , Kryshen Evgeny , Okorokov Vitalii A , Schmidt Ida , Upreti Aditya
Published: March 2023

Opportunities for searches for phenomena beyond the Standard Model (BSM) using heavy-ions beams at high energies are outlined. Different BSM searches proposed in the last years in collisions of heavy ions, mostly at the Large Hadron Collider, are summarized. A few concrete selected cases are reviewed including searches for axion-like particles, anomalous τ electromagnetic moments, magnetic monopoles, and dark photons. Expectations for the achievable sensitivities of these searches in the coming years are given. Studies of CP violation in hot and dense QCD matter and connections to ultrahigh-energy cosmic rays physics are also mentioned.
Assessment of fracture process of engineered cementitious composite (ECC) by time-frequency analysis of acoustic emission signals
Authors: Wang Wentao , Xu Mingfeng , Bao Yi
Published: March 2023

Engineered cementitious composite (ECC), also known as strain-hardening cementitious composite, exhibits high ductility and high toughness. The high ductility and high toughness of ECC are associated with finely-tuned matrix cracking, fiber rupture, and fiber-matrix debonding. This study investigates the fracture process of ECC through a time-frequency analysis of acoustic emission (AE) signals. The frequency characteristics of individual AE hits were used to evaluate different types of damage throughout the fracture process. The evolution of damage was assessed, and the AE energy was calculated. The effects of matrix flaw and fiber content on the fracture process were investigated. The test results revealed that different damage stages featured different AE frequency characteristics, which were used to classify damage types. ECC showed high energy absorption along with the high toughness. This research enhances the understanding of the fracture process of ECC and advances the capability of assessing the damages.
Uniform plasma generation with filament assisted DC discharge in a linear plasma device
Authors: Bora Dibyajyoti , Tarafder Aritra , Biswas Subir , Chowdhuri Malay B , Ghosh Joydeep
Published: March 2023

Uniform and quiescent (δ
n/n < 0.5%) laboratory plasma has been produced in a linear plasma device with a simple filament-assisted DC source without using any magnetic field for plasma confinement. A filament-assisted DC plasma source has been designed, fabricated in-house, and operated successfully to achieve the desired plasma parameters. A stainless steel(ss)-grid is placed in-front of the filament assembly and biased appropriately using a DC-regulated power supply to accelerate thermionically emitted electrons from the heated filaments along the length of the main chamber and facilitate the production of uniform plasma. Heating of the filaments was done by passing a current of ∼3.8 − 4.2 A through it using another DC-regulated power supply. 2-dimensional spatial profiles of plasma density (n

e
), electron temperature (T

e
) and plasma potential (V

P
) obtained from the Langmuir Probe measurements by inserting 4 number of Langmuir Probes inside the plasma from 4 co-linear radial ports of the plasma chamber and scanning them radially with the help of indigenously built probe drive setups reveal spatially uniform plasma generation with n

e
in the range ∼(1 − 2) × 1015 m−3 and T

e
∼ (2.5 − 3.5) eV. Variations of plasma parameters and its spatial uniformity with neutral pressure are also investigated. It is observed that the spatial uniformity of the plasma produced at neutral pressures in the range of ∼(3 − 6) × 10−4 mbar is very good with δ
n/n < 0.5%.
On the duality of unsteady stretching surface flow: the sheet and disk cases
Authors: Mehmood Ahmer , Tabassum Ghulam Dastgir , Usman Muhammad , Dar Aman-ullah
Published: March 2023

This communication is a continuation of our previously published works on the duality of solution of stretching/shrinking surface flows. In this regard, a huge volume of literature is already available advocating that the duality of the solution is a salient feature of the shrinking surface flows, only. It is believed that for a shrinking surface flow the solution does not exist; requires sufficient wall suction for its existence; and is non-unique whenever it exists. On this basis, the shrinking surface flow is believed to be richer in physics by exhibiting more non-linear phenomena. Because of such facts, the available literature has developed a significant miSunderstanding about the shrinking surface flows. It has been established that the shrinking surface flows constitute a superior class of viscous flows instigated by the motion of a continuous surface. However, we think that there is nothing special with the shrinking surface flows, at all. All the fascinations attributed to the shrinking surface flows can be seen for the stretching surface flows, too. The reason behind the appearance of such fascinating features is the retarded nature of the ongoing boundary-layer flow. A retarded boundary-layer can be assisted in a variety of ways; and an assisted, retarded, boundary-layer exhibits a non-unique behavior. In this study, the duality of the solution has been discussed for unsteady stretching surface flow by considering two-dimensional planner and axisymmetric cases corresponding to flat sheet and disk geometries. It is shown that in a stretching surface flow, it is possible to observe the duality of the solution not only in the presence of wall suction but also in the presence of wall injection velocity.
First-order quantum phase transition in the squeezed Rabi model
Authors: Yang Jingwen , Shi Zhicheng , Yang Zhen-Biao , Shen Li-tuo , Zheng Shi-Biao
Published: March 2023

Quantum phase transition and entanglement in the Rabi model with a squeezed light are investigated. We find a special unitary-transformation method that removes the nonintegrable squeezing and counterrotating-wave interactions when the qubit frequency is close to the field frequency. The analytical ground state agrees well with the numerical solution. We demonstrate that the ground state exhibits a first-order quantum phase transition at a critical point induced linearly by the squeezed light. This quantum phase transition requires neither multiple qubits nor an infinite ratio of qubit frequency to field frequency, which solves a critical problem for the theory and experiment in Rabi model. As the qubit-field coupling strength increases, the ground-state entanglement reaches its maximum value at the critical point.
Hybrid multi-fluid-particle simulations of the cosmic neutrino background
Authors: Chen Joe Zhiyu , Mosbech Markus R. , Upadhye Amol , Wong Yvonne Y.Y.
Published: March 2023

Simulation of the cosmic clustering of massive neutrinos is a daunting task, due both to
their large velocity dispersion and to their weak clustering power becoming swamped by Poisson
shot noise. We present a new approach, the multi-fluid hybrid-neutrino simulation, which
partitions the neutrino population into multiple flows, each of which is characterised by its
initial momentum and treated as a separate fluid. These fluid flows respond initially linearly to
nonlinear perturbations in the cold matter, but slowest flows are later converted to a particle
realisation should their clustering power exceed some threshold. After outlining the multi-fluid
description of neutrinos, we study the conversion of the individual flows into particles, in order
to quantify transient errors, as well as to determine a set of criteria for particle conversion.
Assembling our results into a total neutrino power spectrum, we demonstrate that our multi-fluid
hybrid-neutrino simulation is convergent to < 3% if conversion happens at z = 19 and agrees with
more expensive simulations in the literature for neutrino fractions as high as Ω
νh
2 =
0.005. Moreover, our hybrid-neutrino approach retains fine-grained information about the
neutrinos' momentum distribution. However, the momentum resolution is currently limited by
free-streaming transients excited by missing information in the neutrino particle initialisation
procedure, which restricts the particle conversion to z ≳ 19 if percent-level resolution
is desired.
Fluctuating dark energy and the luminosity distance
Authors: Vedder Casper J.G. , Belgacem Enis , Chisari Nora Elisa , Prokopec Tomislav
Published: March 2023

The origin of dark energy driving the accelerated expansion of the universe is still
mysterious. We explore the possibility that dark energy fluctuates, resulting in spatial
correlations. Due to these fluctuations, the Hubble rate itself becomes a fluctuating quantity. We
discuss the effect this has on measurements of type Ia supernovae, which are used to constrain the
luminosity distance. We show that the luminosity distance is affected by spatial correlations in
several ways. First, the luminosity distance becomes dressed by the fluctuations, thereby
differing from standard ΛCDM. Second, angular correlations become visible in the two-point
correlation function of the luminosity distance. To investigate the latter we construct the
angular power spectrum of luminosity distance fluctuations. We then perform a forecast for two
supernova surveys, the ongoing Dark Energy Survey (DES) and the upcoming Legacy Survey of Space
and Time (LSST), and compare this effect with relativistic lensing effects from perturbed
ΛCDM. We find that the signal can rise above the lensing effects and that LSST could test
this effect for a large part of the parameter space. As an example, a specific realisation of such
a scenario is that quantum fluctuations of some field in the early universe imprint spatial
correlations with a predictable form in the dark energy density today. In this case, the Hubble
rate fluctuates due to the intrinsic quantum nature of the dark energy density field. We study
whether the signal of this specific model would be measurable, and conclude that testing this
model with LSST would be challenging. However, taking into account a speed of sound cs
< 1 of the
dark energy fluid can make this model observable.
Optimal metabolic strategies for microbial growth in stationary random environments
Authors: Paola Muntoni Anna , De Martino Andrea
Published: March 2023

In order to grow in any given environment, bacteria need to collect information about the medium composition and implement suitable growth strategies by adjusting their regulatory and metabolic degrees of freedom. In the standard sense, optimal strategy selection is achieved when bacteria grow at the fastest rate possible in that medium. While this view of optimality is well suited for cells that have perfect knowledge about their surroundings (e.g. nutrient levels), things are more involved in uncertain or fluctuating conditions, especially when changes occur over timescales comparable to (or faster than) those required to organize a response. Information theory however provides recipes for how cells can choose the optimal growth strategy under uncertainty about the stress levels they will face. Here we analyse the theoretically optimal scenarios for a coarse-grained, experiment-inspired model of bacterial metabolism for growth in a medium described by the (static) probability density of a single variable (the ‘stress level’). We show that heterogeneity in growth rates consistently emerges as the optimal response when the environment is sufficiently complex and/or when perfect adjustment of metabolic degrees of freedom is not possible (e.g. due to limited resources). In addition, outcomes close to those achievable with unlimited resources are often attained effectively with a modest amount of fine tuning. In other terms, heterogeneous population structures in complex media may be rather robust with respect to the resources available to probe the environment and adjust reaction rates.
A Characterization of the ALMA Phasing System at 345 GHz
Authors: Crew G. B. , Goddi C. , Matthews L. D. , Rottmann H. , Saez A. , Martí-Vidal I.
Published: March 2023

The development of the Atacama Large Millimeter/submillimeter Array (ALMA) phasing system (APS) has allowed ALMA to function as an extraordinarily sensitive station for very long baseline interferometry (VLBI) at frequencies of up to 230 GHz (λ ≈ 1.3 mm). Efforts are now underway to extend the use of the APS to 345 GHz (λ ≈ 0.87 mm). Here we report a characterization of APS performance at 345 GHz based on a series of tests carried out between 2015 and 2021, including a successful global VLBI test campaign conducted in 2018 October in collaboration with the Event Horizon Telescope.
Improving the X-Ray Energy Resolution of a Scientific CMOS Detector by Pixel-level Gain Correction
Authors: Wu Qinyu , Ling Zhixing , Wang Xinyang , Zhang Chen , Yuan Weimin , Zhang Shuang-Nan
Published: March 2023

Scientific Complementary Metal Oxide Semiconductor (sCMOS) sensors are finding increasingly more applications in astronomical observations, thanks to their advantages over charge-coupled devices such as a higher readout frame rate, higher radiation tolerance, and higher working temperature. In this work, we investigate the performance at the individual pixel level of a large-format sCMOS sensor, GSENSE1516BSI, which has 4096 × 4096 pixels, each of 15 μm in size. To achieve this, three areas on the sCMOS sensor, each consisting of 99 × 99 pixels, are chosen for the experiment. The readout noise, conversion gain and energy resolutions of the individual pixels in these areas are measured from a large number (more than 25,000) of X-ray events accumulated for each of the pixels through long time exposures. The energy resolution of these pixels can reach 140 eV at 6.4 keV at room temperature and shows a significant positive correlation with the readout noise. The accurate gain can also be derived individually for each of the pixels from its X-ray spectrum obtained. Variations of the gain values are found at a level of 0.56% statistically among the 30 thousand pixels in the areas studied. With the gain of each pixel determined accurately, a precise gain correction is performed pixel by pixel in these areas, in contrast to the standardized ensemble gain used in the conventional method. In this way, we could almost completely eliminate the degradation of energy resolutions caused by gain variations among pixels. As a result, the energy resolution at room temperature can be significantly improved to 124.6 eV at 4.5 keV and 140.7 eV at 6.4 keV. This pixel-by-pixel gain correction method can be applied to all kinds of CMOS sensors, and is expected to find interesting applications in X-ray spectroscopic observations in the future.
Characterisation of detachment in the MAST-U Super-X divertor using multi-wavelength imaging of 2D atomic and molecular emission processes
Authors: Wijkamp T.A. , Allcock J.S. , Feng X. , Kool B. , Lipschultz B. , Verhaegh K. , Duval B.P. , Harrison J.R. , Kogan L. , Lonigro N. , Perek A. , Ryan P. , Sharples R.M. , Classen I.G.J. , Jaspers R.J.E.
Published: March 2023

In this work, we provide the first 2D spatially resolved description of radiative detachment in MAST-U Super-X L-mode divertor plasmas. The Super-X magnetic configuration was designed to achieve reduced heat- and particle loads at the divertor target compared to conventional exhaust solutions. We use filtered camera imaging to reconstruct 2D emissivity profiles in the poloidal plane for multiple atomic and molecular emission lines and bands. A set of deuterium fuelling scans is discussed that, together, span attached to deeply detached divertor states observed in MAST-U. Emissivity profiles facilitate separate analysis of locked-mode induced split branches of the scrape-off layer. Molecular deuterium Fulcher band emission front tracking reveals that the deuterium electron-impact ionisation front, for which it serves a proxy, detaches at different upstream electron densities in the split branches. Upon detachment of this ionisation front, Balmer emission attributed to molecular activated recombination appears near-target. We report a simultaneous radial broadening of the emission leg, consistent with previous SOLPS-ITER modelling. With increased fuelling this emission region detaches, implying electron temperatures below

∼

1

eV. In this phase, 2D Balmer line ratio reconstruction indicates an onset of volumetric direct electron-ion recombination near-target. At the highest fuelling rates this emission region moves off-target, suggesting a drop in near-wall electron density accompanying the low temperatures.
The dependence of tokamak L-mode confinement on magnetic field and plasma size, from a magnetic field scan experiment at ASDEX Upgrade to full-radius integrated modelling and fusion reactor predictions
Authors: Angioni C. , Bonanomi N. , Fable E. , Schneider P.A. , Tardini G. , Luda T. , Staebler G.M.
Published: March 2023

The dependence of the confinement of a tokamak plasma in L-mode on the magnetic field is explored with a set of dedicated experiments in ASDEX Upgrade and with a theory-based full-radius modelling approach, based on the ASTRA transport code and the TGLF-SAT2 transport model and only using engineering parameters in input, like those adopted in scaling laws for the confinement time. The experimental results confirm the weak dependence of the global confinement on the magnetic field, consistent with the scaling laws for L-mode plasmas and in agreement with the full-radius TGLF-SAT2 predictions. The modelling approach is then extended to numerically investigate the confinement dependence on magnetic field, plasma current and plasma size. The weak dependence of the L-mode confinement on the magnetic field at constant plasma current and plasma size is shown to be produced by a balance between the decrease of confinement mainly produced by the reduction of the E×B shearing rate and the increase of confinement provided by the reduced gyro-Bohm factor, when the magnetic field is increased. The ASTRA/TGLF-SAT2 predicted increase of confinement with increasing plasma size is investigated in comparison with the predictions of the global confinement scaling laws for L-mode plasmas and the Bohm and gyro-Bohm dependencies of confinement, highlighting interesting similarities and important differences. Full-radius TGLF-SAT2 simulations with increasing plasma size are then extended to dimensions which are compatible with reactor relevant fusion power production, using ITER and the European DEMO as references. ASTRA/TGLF-SAT2 predictions of fusion power and confinement of an L-mode fusion reactor are presented at both 5.7 T and 10 T of magnetic field on the magnetic axis.
The analysis on the flow characteristics of supersonic inlet considering structural vibration
Authors: Chen Bing , Chen Hongyang , Mo Tao , Liu Shenshen , Jia Hongyin
Published: March 2023

Inlet is the key part which can influence the performance of airframe-propulsion integration for the air-breathing vehicle. In supersonic or hypersonic condition, the local vibration of the structure will change the integrated performance greatly. The work is to study the influence of the structural vibration of the compression surface on the inlet’s performance, and the vibration factors such as amplitude, wavelength and frequency are evaluated. The influence of the vibration factors on the inlet’s performance is studied. The research shows that the structure of the flow field for the inlet is changed. The influence is more obvious when the vibration occurs to be more closed to the lip. Besides, the wavelength has more influence than the amplitude, and the influence of the frequency is smallest.
The effects of geometry parameters on the aerodynamic performance of CFJ airfoil used by a STOL transport
Authors: Chen Cheng , Xie Zhengyao , He Chengjun , Chen Xian , Huang Jiangtao
Published: March 2023

With the purpose of investigating the effects of geometry parameters of CFJ (Coflow jet) device on the aerodynamic characteristics of the supercritical bacj airfoil used by a STOL transport, we have carried out a computational analysis of CFJ airfoil with different values of injection slot size and location under the low-speed condition. The results show that the lift coefficient decreases gradually with decreasing stall angle, when the injection slot size is increased. When α=8°, with increasing injection slot size, the velocity of blowing jet decreases with decreasing power consumption and increasing aerodynamic effectiveness. Further, with the injection slot shifted towards the downstream direction, the α value corresponding to the maximum effective lift-drag-ratio increases with increasing maximum lift coefficient.
Numerical Simulation of External Flow-Field of a Car Body Based on CFD
Authors: Zhao Dan
Published: March 2023

With the rapid development of computer technology in recent years, this paper explores the feasibility of applying computational fluid dynamics (CFD) to study the external flow-field of automobile body. The computer numerical solution provides the pressure and velocity distribution of the car body, such as aerodynamic pressure field and velocity field, in order to obtain the information of aerodynamic resistance, aerodynamic lift, aerodynamic lateral force and related torque, which can be further used to guide the design and development of automobile. The comparison between numerical simulation results and experiments shows that CFD plays a strong guiding role in the further development of automobile shape and structure.
Research on Fast CFD Simulation of Automobile Flow Field Based on Artificial Intelligence
Authors: Cao Xiaofeng , Wang Qiang , Li Hongyan , Ma Hai
Published: March 2023

Fast automotive aerodynamic evaluation can extremely reduce the design cycles of automotive. This paper establishes a rapid simulation model of the automobile flow field based on the artificial intelligence surrogate model. The end-to-end network is used to map the geometric model, incoming flow conditions, and result. The decoder is used to splice high-dimensional and low-dimensional features to achieve feature sharing. The average MAE error of the optimal model is 5.249%. The average calculation time of a single example is 1.2968s, which is about 0.62% of CFD solver. The simulation result demonstrate that the deep learning method can not only accelerate the calculation, but also can improve the design efficiency of automobile aerodynamic profile with high accuracy.
Investigation on Shallow Trenched-Hole Film Cooling Effectiveness at Turbine Blade Pressure Side
Authors: Yin Jiangjiang , Huang Kenan , Huang Ying
Published: March 2023

Numerical simulations are performed to investigate the effects of shallow trenches on the adiabatic film cooling effectiveness (ηad) of single row film cooling on the pressure side of a turbine guide vane, under the cascade representative conditions. The mainstream inlet Reynolds number is set as 4×105. A single row of film cooling holes are located at 30% axial chord length at the pressure side. Three shallow trenches with different widths (w/d=2, 2.5 and 3) but have the same depth (0.75d) and a cylindrical film cooling hole are compared in the current study at M= 2.0. The results show that the shallow trenched-hole on the pressure side significantly suppresses lift-off of the secondary flow, and effectively improves the spanwise uniformity of film coverage. Therefore, compared with the conventional cylindrical hole (CH), the shallow trenched-hole shows a significant enhanced film cooling performance at M=2.0. By comparisons, it is confirmed that the shallow trenches with w/d=2 and 2.5 are more pronounced than the shallow trench with w/d=3. While the shallow trench with w/d=2.5 takes a little advantage over the w/d=2.
Studying the effect of geometry of micro-cavity on pool boiling by LBM
Authors: Huang Qiang , Zhou Jingzhi , Huai Xiulan , Zhou Feng
Published: March 2023

Pool boiling heat transfer from structured surface is simulated numerically with a 3D OTRT (optimal two relaxation time) Lattice Boltzmann method. This work shows in detail that multiple bubbles grow and coalesce over hydrophilic (θ = 50°) surfaces in 3D view, heat flux transfers from heater surface to fluid, and temperature of heater surface varies with time. Specifically, four types of geometry in microstructure surfaces are examined and compared. It is found that heat flux of S5 is the highest and its wall temperature is the lowest. When compared with S0, the heat flux of S5~S7 increased a lot due to the easier formation of vapor blanket, and cubic shaped cavity alleviates largely this deterioration. Next, the large quantity of heat from the three phase contact line in the vicinity of side wall accounts for bubble nucleation and energy from the evaporation of thin liquid between bubbles and superheated wall helps bubbles to grow further. Besides, it is found that S5 increases nucleate site density, reduces boiling incipience superheat, and enhances remarkably heat transfer performance.
Multi-objective Topology Optimization of the Temperature Field Considering the Material Nonlinearities
Authors: Li Guyang , Li Lin , Peng Zhigang , Hu Sanbao
Published: March 2023

This paper presents a multi-objective topology optimization method for the temperature field considering the material nonlinearities. Although a large number of papers have studied the topology optimizations of the heat transfer problems, none of them considered the influence of the material nonlinearity properties. In this paper, the material nonlinearity is considered. Based on the nonlinear assumption, the mathematical model of the corresponding topology optimization is presented first. Then, the sensitivities of the objectives and the constraints respect to the design variables are derived. And the optimization routines are discussed. After establishing the theories and solving scheme, a software is developed by MATLAB for the topology design of the nonlinear heat transfer. Several nonlinear numerical examples are presented. And the corresponding optimal results generated under the linear assuming are also collected for comparisons. Furthermore, this paper also simply discusses the preventing approaches of instabilities and the implementation methods of some other unusual engineering constraints. These true engineering considerations are very helpful for the real industry design experiences.
Acoustic Field Prediction Method and Simulation Research Based on Acoustic Field Geometric Average Theory
Authors: He Xianwen , Li Zhizhong , Sun Junping
Published: March 2023

In order to meet the capability requirements of submarine radiated noise acoustic field prediction in free field and improve the detection and anti-detection capabilities, this paper proposes an acoustic field prediction method based on the geometric average theory of acoustic field. According to the measured self-noise information, a global search method is used. By calculating the average energy of the spherical, the extended compensation for different point distances is achieved, so as to predict the radiation noise at different distances. Through simulation experiments, it is found that the method proposed in this paper has a fast calculation speed, and the acoustic field prediction accuracy is high.
Soliton solution to the time-like curve shortening flow in the pseudo-sphere
Authors: Chang Jinwei , Wang Yuyan , Zeng Nan , Yu Yanhua
Published: March 2023

A time-like curve on the unit pseudo-sphere can be a solition solution to the time-like curve shortening flow We first introduce the sufficient conditions for it to hold. And by studying the properties of the structure function of non-geodesic curves, I deduce some conditions to be satisfied by the structure function of non-geodesic curves when forming the time-like space plane, and then analyze the influence of the extreme value point of the structure function, and finally discuss the classification according to the time-like space-like situation of the parameter vector.
The Progress of Investigation on Neutrino Properties
Authors: Sheng Taosha , Qu Shitao , Qian Chenghao
Published: March 2023

Generally, particle physics plays an important role in the whole modern physics system. Thereinto, neutrino, as an elementary particle found from beta decay, is of great importance to discover its properties and mechanics. With the help of information retrieve and literature review, this paper aims at helping recollecting sorts of knowledge, e.g., the developing history of the principle, different kinds of matrix expressions, field theories etc. Additionally, some possible future developing directions have been proposed. Moreover, plenty of analytical models and experimental approaches for generating massive neutrinos are demonstrated, e.g., Lagrangian and beta decay. More experiments need to be carried out for the sake of verifying the theoretical predictions. Overall, these results offer a guideline for completing the Standard Model and hopefully the Grand Unified Theory, such as Majorana mass term.
Research on Atmospheric Turbulence Distortion Measurement Based on Compressed Sensing Technology
Authors: Huang Kaichen , Deng Hengliang , Lin Yanlong
Published: March 2023

The Hartmann wavefront sensor can measure the phase change of atmospheric turbulence in real time and realize the measurement of the distorted wavefront signal of atmospheric turbulence. However, existing Hartmann wavefront sensor microlens arrays are generally small, which limits their spatial resolution capabilities. By introducing compressed sensing technology into wavefront detection, this paper breaks through the limitations of the traditional Nyquist sampling theorem and achieves higher resolution spatial wavefront detection with a smaller microlens array.
Effect of collision of particles on migration behaviour in hydrocyclone
Authors: Gao Yang , Pei Xiaohan , Cao Gang , Yu Jiaqing , Zhao Xiaojie , Li Feng
Published: March 2023

The CFD-DEM coupling calculation method is used to study and analyse the influence of different particle sizes on the particle motion behaviour when they collide in the hydrocyclone. The results show that when the particles move in the hydrocyclone, they hardly collide with the inner wall of the hydrocyclone, and the collision position of the particles is mainly concentrated in the 140mm-80mm range of the hydrocyclone. When the particles collide, the particles are suddenly subjected to the contact reaction caused by the collision, and the trajectory will be adjusted from following the fluid streamline to circling at a certain longitudinal position, and the particle size increases with the increase of the particle size.