bluuebunny/crossref_metadata_2025 huggingface dataset:
Study on the key parameters of ice particle air jet ejector structure
Authors: Man Wang , Zehua Niu , Liu Yong
Published: August 2024

Existing ice particle jet surface treatment technology is prone to ice particle adhesion during application, significantly affecting surface treatment efficiency. Based on the basic structure of the jet pump, the ice particle air jet surface treatment technology is proposed for the instant preparation and utilization of ice particles, solving the problem of ice particle adhesion and clogging. To achieve efficient utilization of ice particles and high-speed jetting, an integrated jet structure for ice particle ejection and acceleration was developed. The influence of the working nozzle position (Ld), expansion ratio (n), and acceleration nozzle diameter ratio (Dn) length-to-diameter ratio (Ln) on the ice particle ejection and acceleration was systematically studied. The structural parameters of the ejector were determined using the impact kinetic energy of ice particles as the comprehensive evaluation index, and the surface treatment test was conducted to verify the results. The study shows that under 2 MPa air pressure, the ejector nozzle parameters of n = 1.5, Dn = 4.0, Ld = 4, and Ln = 0 mm can effectively eject and accelerate the ice particles. The aluminum alloy plate depainting test obtained a larger paint removal radius and resulted in a smoother aluminum alloy plate surface, reducing the surface roughness from 3.194 ± 0.489 μm to 1.156 ± 0.136 μm. The immediate preparation and utilization of ice particles solved the problems of adhesion and storage in the engineering application of ice particle air jet technology, providing a feasible technical method in the field of material surface treatment.
PUM1-TRAF3 fusion protein activates non-canonical NF-κB signaling via rescued NIK in biliary tract cancer
Authors: Jung Dawoon E. , Seo Mi-Kyoung , Jo Jung Hyun , Kim Kahee , Kim Chanyang , Kang Hyundeok , Park Soo Been , Lee Hee Seung , Kim Sangwoo , Song Si Young
Published: August 2024

Discovery and verification of diagnostic or therapeutic biomarkers for biliary tract cancer (BTC) is challenging owing to the low prevalence of the disease. Here, we identified and investigated the clinical impact of a fusion gene, Pumilio1-tumor necrosis factor receptor-associated factor 3 (PUM1-TRAF3), caused by 1;14 chromosomal translocation in BTC. PUM1-TRAF3 was initially identified in the RNA-sequencing of five BTC surgical tissues and confirmed by fluorescence in situ hybridization. Expression of the fusion gene was validated in an expanded cohort (5/55, 9.1%). Establishment and molecular assessment of PUM1-TRAF3 expressing BTC cells revealed that PUM1-TRAF3 activates non-canonical NF-κB signaling via NF-κB-inducing kinase (NIK). Abnormal TRAF3 activity, driven by competitive binding of PUM1-TRAF3 and TRAF3 to NIK, led to NIK rescue followed by P52/RelB nuclear translocation, all of which were reverted by an NIK inhibitor. The elevated expression of NIK and activated NF-κB signaling was observed in the PUM1-TRAF3-expressing regions of patient tissues. Expression of the PUM1-TRAF3 fusion was significantly correlated with strong NIK expression, which is associated with a poorer prognosis for patients with BTC. Overall, our study identifies a new fusion gene, PUM1-TRAF3, that activates NIK and non-canonical NF-κB signaling, which may be beneficial for developing precise treatment strategies for BTC.
Upper bounds on overshoot in SIR models with nonlinear incidence
Authors: Nguyen Maximilian M.
Published: August 2024

We expand the calculation of the upper bound on epidemic overshoot in SIR models to account for nonlinear incidence. We lay out the general procedure and restrictions to perform the calculation analytically for nonlinear functions in the number of susceptibles. We demonstrate the procedure by working through several examples and also numerically study what happens to the upper bound on overshoot when nonlinear incidence manifests in the form of epidemic dynamics over a contact network. We find that both steeper incidence terms and larger contact heterogeneity can increase the range of communicable diseases at which the overshoot remains a relatively large public health hazard.
Antifragility in complex dynamical systems
Authors: Axenie Cristian , López-Corona Oliver , Makridis Michail A. , Akbarzadeh Meisam , Saveriano Matteo , Stancu Alexandru , West Jeffrey
Published: August 2024

Antifragility characterizes the benefit of a dynamical system derived from the variability in environmental perturbations. Antifragility carries a precise definition that quantifies a system’s output response to input variability. Systems may respond poorly to perturbations (fragile) or benefit from perturbations (antifragile). In this manuscript, we review a range of applications of antifragility theory in technical systems (e.g., traffic control, robotics) and natural systems (e.g., cancer therapy, antibiotics). While there is a broad overlap in methods used to quantify and apply antifragility across disciplines, there is a need for precisely defining the scales at which antifragility operates. Thus, we provide a brief general introduction to the properties of antifragility in applied systems and review relevant literature for both natural and technical systems’ antifragility. We frame this review within three scales common to technical systems: intrinsic (input–output nonlinearity), inherited (extrinsic environmental signals), and induced (feedback control), with associated counterparts in biological systems: ecological (homogeneous systems), evolutionary (heterogeneous systems), and interventional (control). We use the common noun in designing systems that exhibit antifragile behavior across scales and guide the reader along the spectrum of fragility–adaptiveness–resilience–robustness–antifragility, the principles behind it, and its practical implications.
Development of zeolite adsorbents for CO2 separation in achieving carbon neutrality
Authors: Tao Zeyu , Tian Yuanmeng , Wu Wei , Liu Zhendong , Fu Weiqi , Kung Chung-Wei , Shang Jin
Published: August 2024

The escalating atmospheric CO2 concentration has become a global concern due to its substantial influence on climate change, emphasizing the necessity of carbon capture to achieve carbon neutrality. Adsorption-based CO2 separation is a promising approach for carbon capture, highlighting the importance of developing solid porous materials as effective adsorbents. Among these porous materials, zeolites stand out as promising adsorbents due to their extensively tunable adsorption/separation properties, superior structural stability, non-toxicity, and cost-effectiveness. This review provides a comprehensive overview of the mechanisms, strategies, and prospects for zeolite development in separating CO2 from critical scenarios, encompassing flue gas (CO2/N2), natural/bio/landfill gases (CO2/CH4), and air, respectively. This review outlines general mechanisms for CO2 separation using zeolites, discusses specific strategies for zeolite development, and concludes with a summary of current findings and an outlook for future research.
Transition Metal-based Nanofoams for Electrochemical Systems
Authors: de Fátima Montemor Maria , Fernandes Diana M. , Adan-Mas Alberto , Alves Ana Catarina , Garcia Carvalho Gabriel , Marques Inês S.
Published: August 2024

Metal foams are lightweight materials inspired by structures in nature. They are defined as three-dimensional frameworks with interconnected porous structures – nano-, meso- and macropores - that combine essential physical and mechanical features of metals with a highly porous nanoarchitectures. These types of porous materials can be used in a variety of different scientific fields and, as a result, have gained increasing attention in recent years. Given the heightened academic and industrial interest in efficient materials, sparked by the high demand for new clean technologies, this book is more relevant and timelier than ever.
The emergence of a robust lithium gallium oxide surface layer on gallium-doped LiNiO2 cathodes enables extended cycling stability
Authors: Mishra Mritunjay , Yao Koffi P. C.
Published: August 2024

The capacity retention of high-capacity cobalt-free LiNiO2 can be doubled by surface α-LiGaO2.
Does the number of cells of individual strains correlate with their contribution to the total substrate turnover within a microbial community?
Authors: Buchner Daniel , Scheckenbach Johannes , Martin Philipp R. , Haderlein Stefan B.
Published: August 2024

In a synthetic binary culture, cell numbers derived by qPCR did not reflect the contribution of individual strains to the total substrate turnover.
Anisotropic charge transport study of highly oriented P4T2F-HD thin film fabricated at air–liquid interface through second harmonic generation (SHG) analysis
Authors: Shyam Radhe , Manaka Takaaki , Prakash Rajiv
Published: August 2024

Carrier transport anisotropy in highly oriented P4T2F-HD thin films prepared by the UFTM technique was directly visualized using the sophisticated SHG imaging method.
The synthesis and bioactivities of ROCK2 inhibitors with 1,2-dithiolan-3-yl motif
Authors: Cao Ruolin , Du Fangyu , Liu Zhiqiang , Cai Pengcheng , Qi Minggang , Xiao Wei , Bao Xuefei , Chen Guoliang
Published: August 2024

Rho-associated coiled-coil containing kinase (ROCK) plays an important role in inflammation.
Modeling mechanochemistry: pressure dependence of Diels–Alder cycloaddition reaction kinetics
Authors: Hopper Nicholas , Sidoroff François , Cayer-Barrioz Juliette , Mazuyer Denis , Chen Bo , Tysoe Wilfred T.
Published: August 2024

We analyze the effect of pressure on the Diels–Alder (D–A) dimerization reactions using Evans–Polanyi (E–P) theory, a thermodynamic analysis of the way in which a perturbation, in this case a hydrostatic pressure, modifies a reaction rate.
Target-selective cytosolic delivery of cargo proteins using the VHH-presented OLE-ZIP capsules
Authors: Takahashi Kousuke , Inoue Yasumichi , Hida Shigeaki , Hosoda Ryuki , Umezawa Naoki , Akiba Isamu , Umetsu Mitsuo , Mizuno Toshihisa
Published: August 2024

In the pursuit of a new generation of protein pharmaceuticals, the efficient delivery of these therapeutics into cells stands out as a crucial challenge.
Partner selection in business mergers: a data envelopment analysis approach
Authors: Ibn Boamah Mustapha , Amin Gholam R.
Published: August 2024

Business mergers and partnerships could create opportunities for the decision making units (DMUs) involved to collectively enhance their efficiency. Estimating potential merger gains for a set of given merging DMUs using data envelopment analysis (DEA) and inverse DEA have been discussed in the literature. This paper develops new inverse DEA models for partner selection in a merger. The developed models extend the literature by finding optimal sets of partners that would maximize merger gains among a group of potential merging partners. The results of this study are useful to business managers seeking to merge to improve competitiveness. Data from the top US commercial banks is used to show the applicability of the proposed DEA models in this study.
Fixação de fragmento osteocondral com palitos ósseos autólogos em joelho – Um relato de caso
Authors: Resch Elemar da Silva , Machry Sandrey da Rosa , Zottis Caio César , Barros Fernando Knoll
Published: August 2024

Lesões osteocondrais no joelho são incomuns no esqueleto imaturo e costumam estar relacionadas com atividades esportivas.

De acordo com o tamanho e a localização do fragmento, a fixação se faz necessária. A técnica padrão é realizada através da redução aberta e fixação interna com parafusos metálicos, que precisam retirados em um segundo procedimento, após consolidação.

Como alternativa, visando a redução de risco e morbidade, existe a fixação do fragmento osteocondral com palitos ósseos autólogos.

O presente trabalho relata a execução dessa técnica cirúrgica em um paciente de 13 anos que lesionou o joelho direito durante uma partida de futebol.
Um estudo de coorte retrospectiva dos efeitos da taxa de preenchimento do canal e da alteração da densidade óssea femoral nos desfechos de hastes anatômicas e cônicas de cunha dupla
Authors: Chompoosang Thakrit , Ploynumpon Patcharavit
Published: August 2024

Objetivo Este estudo teve como objetivo comparar as alterações na densidade óssea femoral proximal em radiografias de acompanhamento e as taxas de preenchimento proximal das hastes anatômicas ou cônicas de cunha dupla.

Métodos O estudo incluiu pacientes com idade entre 18 e 80 anos submetidos à artroplastia total primária do quadril com os dois tipos de hastes entre 2017 e 2019 e que tinham radiografias de acompanhamento por até um ano. As taxas de preenchimento do canal em três níveis (trocânter menor [TM], 2 cm acima do TM e 7 cm abaixo do TM) foram determinadas pelo método de densitometria ideal. As alterações na densidade óssea femoral foram medidas pelo método de zoneamento de Gruen.

Resultados Ao todo, 92 pacientes (76% do sexo feminino e 24% do sexo masculino) atenderam aos critérios de inclusão deste estudo. A média de idade foi de 53,86 ± 13,00 anos. A taxa de preenchimento do canal no grupo com hastes cônicas de cunha dupla (Accolade II) foi significativamente maior do que no grupo com haste anatômica (ABGII) (p < 0,001, p < 0,001 e p = 0,013) em todos os níveis de medição. Não foi notada diferença significativa entre os dois tipos de hastes nas alterações da densidade óssea femoral nas zonas 1 e 4. Porém, diferenças significativas na alteração óssea femoral foram detectadas, já que a perda óssea foi maior no grupo com haste anatômica, na zona 7 (−25% versus −17%; p = 0,010).

Conclusão A haste cônica de cunha dupla gerou uma taxa de preenchimento do canal significativamente maior do que a haste anatômica em todos os níveis, mas com menor perda de densidade óssea femoral em radiografias pós-operatórias de acompanhamento na zona 7. Além disso, nas zonas 1 e 4, não houve perda significativa de densidade óssea femoral.
Clostridioides Difficile Infection Presenting with Fulminant Colitis
Authors: Sobrado Lucas F. , Anderson Cristan , Steele Scott R.
Published: August 2024

Clostridioides difficile infection (CDI) is a common hospital-acquired infection, typically presenting with watery diarrhea and colitis. Most cases are managed with clinical support and antibiotics. Recently, more virulent strains have been associated with life-threatening infections. Surgery plays a role for complicated cases failing clinical treatment or with complications, such as bowel perforation and peritonitis. The present study reports the case of a 62-year-old female with CDI and fulminant colitis requiring urgent surgery. Surgeons should be aware of this presentation and involved early in the care of these patients, as clinical deterioration can occur very rapidly.
Efficacy of Metronidazole in the Conservative Treatment for Appendiceal Mass
Authors: Ogata Seiya , Shimizu Hirofumi , Machino Kakeru , Kakuta Keiichi , Mimori Kotaro , Minami Yosuke , Goto Yudai , Yamashita Michitoshi , Tanaka Hideaki
Published: August 2024

Background In patients with complicated appendicitis, interval appendectomy (IA) with a single broad-spectrum antibiotic sometimes fails. We reviewed our experience of adding metronidazole (MNZ) in such situations.

Methods Medical records of children with an appendiceal mass treated with broad-spectrum antibiotics followed by IA from March 2009 to May 2019 were reviewed. In the latter period (after April 2015, Group L, n = 14), MNZ was added if symptoms were not improved by a 3- to 4-day course of antibiotics. The body temperature, white blood cell count (WBC), serum C-reactive protein (CRP), treatment failure, and hospital stay for the initial treatment were collected in the earlier period (Group E, n = 14) and Group L.

Results There was no treatment failure. Group E tended to require a longer hospital stay (14.0 vs. 11.1 days, p = 0.099); however, the temperature, WBC, and CRP on admission were not significantly different. In the MNZ-added group (n = 8), the mean rate of change (per day) in WBC before and after the addition of MNZ were −288 ± 1,155 and −3,870 ± 1,634, respectively (p = 0.001). All patients underwent IA in about 3 months.

Conclusions This preliminary study may indicate the efficacy of MNZ combined with a broad-spectrum antibiotic followed by IA for intractable appendiceal masses.
Plans and outcomes for mixed use in new apartment buildings: A Gothenburg programme for suburban infills
Authors: Gregorowicz-Kipszak Joanna , Bröchner Jan , Hagson Anders
Published: August 2024

Cities may wish to create more lively urban areas by zoning for mixed uses. The purpose here is to identify factors explaining the gaps between plans and outcomes for non-residential uses of ground floors in a Swedish housing programme with 30 development plans for apartment building infill in low-density suburbs already dominated by apartment buildings. We assume that outcomes depend on zoning, urban design factors, mobility factors and socio-economic factors. Documents and field observations reveal that vertical zoning has had limited effects. Correlation analysis indicates that active non-residential ground floor frontages reflect access to public transport, while vacancies are associated inversely with area incomes. Typical ground floor uses are the retail sale of food and services to the human body. A political goal of active ground floors in low-density suburbs might need subsidies if vacancies are to be avoided.
Academic freedom and the unknown: credibility, criticism, and inquiry among the professoriate
Authors: Yingling Marissa E. , Yingling Charlton W.
Published: August 2024

In the U.S., military and intelligence personnel, the National Aeronautics and Space Administration (NASA), scholars, professional organizations, legislators, journalists, and others are requesting study of UFOs, recently renamed Unidentified Aerial/Anomalous Phenomena (UAP) by the U.S. government. Yet disinformation, misidentifications, hoaxes, and entertainment cloud the subject. Combined, these factors pertain to wider debates about the parameters of academic freedom. Here, we asked faculty across 14 disciplines at 144 research universities (N = 1460) to register insights about UAP in the academy via confidential survey. To the authors’ knowledge, this is the first national study to examine scholars’ evaluations of academic credibility and possible social or professional repercussions—including concerns for tenure, promotion, and academic freedom—in relation to UAP. Results suggest that faculty concern that conducting UAP-related research would jeopardize their tenure or promotion might exceed colleagues’ actual negativity toward such research on tenure or promotional votes. Only 7.4% of faculty responded that “Yes” they would vote negatively (“No” = 61.92%, “Maybe” = 27.95%), though 52.67% reported some degree of concern for tenure or promotion. Faculty more frequently reported some degree of concern for social rather than professional repercussions. Concern for ridicule totaled 69.04%. Among all faculty, 66.24% reported that their discipline was capable to some degree of evaluating the evidence or significance of UAP. The disciplines of physics (95.82%), philosophy (88.73%), anthropology (87.09%), and engineering (83.15%) most frequently reported capability. Those who most frequently responded “Not at All” capable belonged to economics (59.7%), literature/English (54.46%), nursing (53.33%), and art and design (51.52%). Notably, although physics faculty most frequently responded that their discipline was capable to some degree of evaluation, nearly three in four reported some degree of concern about ridicule. From 250 open-ended responses, we generated 14 themes pertaining to research or teaching. To promote transparency, highlight a range of perspectives, and facilitate debate, for each theme we included at least 3 example quotes. In the context of ongoing developments, we discuss results, which underscore the complexity of beleaguered subjects and render conversations about academic freedom and UAP timely, relevant, and necessary.
The use of interactional metadiscourse markers by Saudi EFL male and female college students: the case of a gender-sensitive topic
Authors: Al-Otaibi Ghuzayyil Mohammed , Hussain Abeer Abdulhadi
Published: August 2024

A few studies have explored the use of interactional metadiscourse markers in argumentative writing by male and female college students. More importantly, none explored the topic of metadiscourse resources with respect to gender-sensitive topics. Thus, the present study aims at examining the exploitation of interactional metadiscourse markers by Saudi male and female English as a Foreign Language (EFL) college students in their writing about ‘Who are Better Drivers, Men or Women?’. The study is corpus-based on students’ essays. The corpus consists of four sub-corpora: (a) men favouring men, (b) men arguing for women, (c) women arguing for men and (d) women writing in favour of women. We followed a qualitative and quantitative approach to data analysis. Using AntConc and Hyland’s (2005) metadiscourse model of interactional markers, the results reveal that female writers employed attitudinal lexis, hedges, self-mentions and boosters more than male writers. As for the variables of gender and stance choice, females arguing for men’s driving significantly utilised hedges more than the other three groups. Additionally, female writers writing in support of female drivers significantly used self-mentions more than male writers arguing for men’s driving. This study shows that sensitive topics may cause a difference in the distribution of metadiscourse markers used by people of both genders, and it provides some pedagogical implications for EFL instructors and curriculum developers.
Multifunctional nanoparticle system provides both diagnostic, therapeutic applications
Authors: Thompson Avery
Published: August 2024

Combining multiple nanoparticles within a carrier membrane enables heat delivery and real-time temperature monitoring simultaneously.
Design of the electron cyclotron resonance (ECR) plasma source for the space plasma environment research facility
Authors: Yang J. H. , Ling W. B. , Jin C. G. , Tang H. B. , Zhou H. , E P.
Published: August 2024

The Space Plasma Environment Research Facility (SPERF) was built in Harbin to study the three-dimensional magnetic reconnection and wave–particle interactions relevant to space physics in laboratory settings. A 2.45 GHz Electron Cyclotron Resonance (ECR) plasma source is adopted in the device to simulate the Earth’s magnetosphere and achieve the scientific goals. In this paper, the design of the ECR plasma source is presented. The structures of the microwave source, the microwave transfer system, and the antenna are introduced. Additionally, the resonant surfaces are computed to predict the locations of microwave absorption. The absorption mechanisms of the microwave in the SPERF are also discussed. The discharge experiment demonstrates the utility of the ECR source in simulating the Earth’s magnetosphere. The successful operation of the source indicates that the ECR discharge is a powerful tool for creating a plasma environment in a large plasma experimental device.
Estimation of Carleman operator from a univariate time series
Authors: Semba Sherehe , Yang Huijie , Chen Xiaolu , Wan Huiyun , Gu Changgui
Published: August 2024

Reconstructing a nonlinear dynamical system from empirical time series is a fundamental task in data-driven analysis. One of the main challenges is the existence of hidden variables; we only have records for some variables, and those for hidden variables are unavailable. In this work, the techniques for Carleman linearization, phase-space embedding, and dynamic mode decomposition are integrated to rebuild an optimal dynamical system from time series for one specific variable. Using the Takens theorem, the embedding dimension is determined, which is adopted as the dynamical system’s dimension. The Carleman linearization is then used to transform this finite nonlinear system into an infinite linear system, which is further truncated into a finite linear system using the dynamic mode decomposition technique. We illustrate the performance of this integrated technique using data generated by the well-known Lorenz model, the Duffing oscillator, and empirical records of electrocardiogram, electroencephalogram, and measles outbreaks. The results show that this solution accurately estimates the operators of the nonlinear dynamical systems. This work provides a new data-driven method to estimate the Carleman operator of nonlinear dynamical systems.
Compact Compton
γ
-ray source from a spatiotemporal-modulated pulse scattering a high-energy electron beam
Authors: Yu Q. , Gu Y. J. , Zhang Y. , Kong Q. , Kawata S.
Published: August 2024

A novel plasma mirror is proposed for realizing all-optical Compton scattering, and its performance is compared with that of planar and concave plasma mirrors. Compared to a planar mirror, a concave mirror augments the radiation energy, but it decreases the collimation of the emitted photon beam. With the aid of the increased pulse length of the reflected laser, our proposed plasma mirror boosts the radiation energy and simultaneously improving the collimation of the emitted radiation. The pulse length and radius of the reflected laser can be controlled by adjusting the parameters of the proposed plasma mirror. The dependences of the pulse length and radius on the mirror parameters have been demonstrated. The impact of non-ideal conditions encountered in real experiments on the proposed mechanism has been discussed, which precisely demonstrates the robustness of the proposed mechanism. Additionally, the required gas density for a wakefield accelerator is derived to achieve optimal scattering under the given plasma mirror configurations.
Dynamical behavior of lubricant molecules under boundary lubrication explored via molecular dynamics simulations
Authors: Liu Dongjie , Liu Zilu , Wei Jinjia , Chen Fei
Published: August 2024

Boundary lubrication with extremely thin films widely occurs in various situations, for instance, in micro-electromechanical system lubrication and hard disk drive lubrication. Lubrication performance is significantly affected by the surface layer properties and interactions between solids and liquids. However, the molecular dynamical behaviors are still unclear. Thus, our work considers the dynamical behaviors of molecules under boundary lubrication via molecular dynamics simulations. Different pressures and metal slab shapes are chosen as the variable conditions. The results indicate that a smooth metal slab model has a special conformation recovery process during compressing under medium pressures. After inducing shear velocity, the lubrication film exhibits sticky, stick–slip, or slip flows under different pressures. Sticky flow is accompanied by a conformation adjustment consisting of conformation recovery, chain alignment, and structure equilibrium, but there is no chain alignment step in the other two flow modes. The conformation recovery includes atomic adsorption onto the Fe wall under small and medium pressures. Under large pressures, the conformation recovery refers to atomic desorption phenomena. In addition, some properties, such as gyration and chain orientation, are strongly modified by the solid surface and show distinct differences along the pressing direction. Under the same simulation conditions, the rough wall model shows no slip behaviors attributed to the increased equivalent contact wall area and stronger pinning effect. Our work provides new insights into understanding the in-depth mechanism of boundary lubrication, providing theoretical guidance in developing advanced boundary lubrication techniques.
Complex flow dynamics for a static triple-box girder under various angles of attack
Authors: Meng Hao , Qiu Chen , Yang Wenhan , Gao Donglai
Published: August 2024

Due to the existence of the upstream and downstream gap, the flow dynamics around a separated triple-box girder becomes quite complex. This work explores the flow dynamics around a triple-box girder, i.e., multiple separation–reattachment effect, shear layers' impingement–rebound effect, separated- and double-shear-layer instability, etc. Three angles of attack (AOAs), i.e., 0°, +5°, and −5°, were considered for investigating the vortex dynamics of a classical triple-box girder, and the Reynolds number (Re) was set at 1.05 ×104. The time-averaged and instantaneous flow fields as well as the distribution of the fluctuating magnitude are discussed. The results show that, under 0°AOA, the upstream gap flow (flow in the upstream gap) is characterized by the shear layer impingement while intermittent vortex-shedding appears in the downstream gap. Time–frequency analysis and instantaneous flow fields reveal that the spectral intermittency is caused by oscillations of the lower shear layer. The different flow dynamics are analyzed in detail by the spectral proper orthogonal decomposition analysis. Under +5°AOA, the interactions of the shear layers in both gaps show weak periodicity, and the instability of the separated shear layer dominates the whole flow field. Under −5°AOA, the double-shear-layer instability dominates both gap flows. The periodical shedding vortices are observed simultaneously in both gaps with varied dominant frequencies. The complex impacts of the impingement–rebound effect as well as the essence of the “multi-frequency” phenomenon are also revealed.
Prediction of steady hydrodynamic performance of pump jet propulsion based on free wake vortex model
Authors: Weng Kaiqiang , Shao Fei , Li Jiandong , Sun Shuai , Wang Chao
Published: August 2024

Due to mutual interference between various components, the transitional motion of fluid particles in the flow field of pump jet propulsion becomes more complex and variable. Additionally, the vortex structure at the wake can undergo severe contraction and deformation. To further improve the accuracy of predicting the hydrodynamic performance of pump jet propulsion, this paper proposes a time-varying, space-varying, and induced velocity-varying free wake numerical calculation model based on potential flow theory. A set of hydrodynamic performance prediction methods that consider the interference of the free wake model is also established. Furthermore, a velocity smoothing model based on time reversal is constructed based on the distribution pattern of numerical singularity points during the induced velocity calculation process, which enhances the robustness of the calculation program. By comparing and analyzing the numerical calculation results with experimental results, including pressure, circulation distribution, and hydrodynamic performance, the accuracy of the free wake model proposed in this paper is verified. The results also demonstrate that the free wake model proposed in this paper can effectively improve the prediction accuracy of the hydrodynamic performance of the pump jet propulsion.
Prandtl number effects on heat transfer in viscoelastic turbulent channel flow
Authors: Kim Kyoungyoun
Published: August 2024

In viscoelastic turbulent wall-bounded flows, the suppression of near-wall vortical structures due to viscoelastic stress significantly reduces both the frictional drag and heat transfer. To investigate the effect of the Prandtl number (Pr) on the heat transfer reduction rate (HTR), we conducted a series of direct numerical simulations of passive scalar transport using the finitely extensible nonlinear elastic-Peterlin (FENE-P) model for a viscoelastic turbulent channel flow. Various values of Pr from 0.1 to 5.0 were tested at a frictional Reynolds number of 125. The results revealed that the HTR was almost constant for Pr≥2.0 at a given drag-reduced flow and was higher than the drag reduction rate, aligning with previous experimental observations. However, in the case of lower-Pr fluids (Pr≤0.7), the HTR decreased as Pr decreased. The variation in the Nusselt number (Nu) for Pr was examined by decomposing Nu into three components: laminar flow contribution, turbulent heat flux contribution, and contribution owing to the deviation in the mean velocity profile from the laminar profile. For lower-Pr fluids (Pr≤0.7), the contribution of the wall-normal turbulent heat flux was insufficient to achieve the same HTR as that observed for Pr = 5.0. Despite the reduced wall-normal turbulent heat flux in the viscoelastic flows, the instantaneous flow fields showed a substantial similarity in the turbulent structures of the Reynolds shear stress compared to those of the wall-normal turbulent heat flux, which was maintained at various Pr values. This was also statistically confirmed through the weighted joint probability density function.
An innovative three-dimensional computational fluid dynamics-iterative ensemble Kalman filter model for the prediction of heavy gas leakage and dispersion in enclosed workplaces: Case study for hydrogen sulfide leakage
Authors: Wang Shasha , Zheng Xing , Ng S. Thomas , Bao Zhikang
Published: August 2024

Toxic heavy gas leakage in enclosed workplaces can result in severe safety accidents. Reasonable estimations of toxic heavy gas leakage and its subsequent concentration distribution are crucial for disaster assessment and emergency response. This study combines a three-dimensional (3D) gas dispersion model developed based on computational fluid dynamics (CFD) with the iterative ensemble Kalman filter (IEnKF) algorithm for accurate estimation of heavy gas leakage source parameters and detailed prediction of concentration distributions, with a case study of hydrogen sulfide (H2S) leakage. The inversions of two uncertain parameters are considered: H2S leakage velocity and air supply velocity. The results show that the 3D CFD-based gas dispersion model can work well with the robust IEnKF algorithm to predict the spatiotemporal concentration distribution of heavy gas with high confidence. Moreover, the multiple correction procedures performed in the IEnKF module can greatly improve the efficiency and accuracy of parameter estimations compared to the single correction of the EnKF algorithm. When the maximum number of iterations is set to ten, the assimilation time steps required to achieve satisfactory estimations of uncertain parameters are reduced by 86.67%; the accuracy of H2S leakage velocity and air supply velocity estimation is improved by 10.59% and 46.25%, respectively. In addition, after 13 assimilation time steps, the estimated H2S leakage velocity (17.2 m/s) is almost equal to the assumed true value (17 m/s). This study provides a novel approach to assess the impact of poisonous dense gas leakage in enclosed workplaces.
Defect behavior during growth of heavily phosphorus-doped Czochralski silicon crystals. I. Experimental study
Authors: Hourai Masataka , Narushima Yasuhito , Torigoe Kazuhisa , Nonaka Naoya , Koga Koutaro , Ono Toshiaki , Horie Hiroshi , Sueoka Koji
Published: August 2024

This report (I) aims to investigate defect behavior during the growth of heavily phosphorus (P)-doped Czochralski silicon (HP-Cz-Si) crystals. The defects and P chemical states in as-grown crystals with a resistivity of 0.6 mΩ cm and the wafers annealed at around 600 °C were evaluated by transmission electron microscopy and hard x-ray electron spectroscopy (HAXPES). Micro-dislocation loops (MDLs) were observed in the bottom portion of the crystal, and larger stacking faults (SFs), including complex dislocation clusters, were observed in the middle portion. HAXPES revealed two different P states, P1 and P2. P1 was attributed to a substitutional P (Ps). The P2 present in as-grown crystals was found to be electrically active, while the newly formed P2 after annealing was electrically inactive, indicating that they are in different states. HAXPES evaluation of HP-Cz-Si after electron irradiation showed similar behavior to P2 after annealing, suggesting that P-vacancy (V) clusters are formed when the crystals are held at temperatures below 600 °C during crystal growth. Combining the experimental results with our theoretical analysis in the report (II) based on density functional theory calculations, we identified the following defect formation mechanisms. Interstitial P (Pi) atoms introduced at the melting point become supersaturated during cooling to 600 °C, and MDLs are generated by the aggregation of Si self-interstitials (Is) released through a position exchange from Pi to Ps. In crystal portions with a long residence time below 600 °C, supersaturated Ps transforms into P–V clusters, and Is generated simultaneously are absorbed by the MDLs, which grow into SFs containing dislocation clusters.
Influence of cavity geometry on the bubble dynamics of nucleate pool boiling
Authors: Whiting M. S. , van den Bergh W. J. , Theodorakis P. E. , Everts M.
Published: August 2024

Nucleate pool boiling is known for its exceptional heat transfer coefficients, with the use of cavities further improving bubble nucleation and heat transfer rate. To promote this heat transfer enhancement technique, a thorough understanding of the influence of cavity geometry on single bubble dynamics is required. The influence of depth and radius of cylindrical and conical cavities on the bubble dynamics of nucleate pool boiling of R1234yf were numerically investigated. The cavity radius was varied between 50 and 400 μm and the cavity depth between 100 and 1000 μm at a fixed heat flux of 28 kW/m2. It was found that the maximum equivalent diameter prior to departure was constant for cavities with radii smaller than 120 μm, while it increased linearly when increasing the cavity radius further. Cylindrical cavities exhibited high stability regardless of cavity radius or depth whereas conical cavities showed a decrease in vapor retention with increasing cavity angle. During the necking phase, the bubble interface became pinned at the cavity edge, depending on conical cavity angle, implying that smaller radii allowed for enhanced surface rewetting. Conical cavities could be considered as cylindrical cavities when the cavity angle was less than a quarter of the interface contact angle. When translating the single cavity findings to cavity array design, cylindrical cavities were recommended as they allowed for stable bubble behavior. For increased nucleation zones and rewetting, a sub-critical radius was recommended. Wider cavities were recommended for high superheat conditions as larger bubbles could enhance bubble growth.
A new computational framework for spinor-based relativistic exact two-component calculations using contracted basis functions
Authors: Zhang Chaoqun , Peterson Kirk A. , Dyall Kenneth G. , Cheng Lan
Published: August 2024

A new computational framework for spinor-based relativistic exact two-component (X2C) calculations is developed using contracted basis sets with a spin–orbit contraction scheme. Generally contracted, j-adapted basis sets of p-block elements using primitive functions in the correlation-consistent basis sets are constructed for the X2C Hamiltonian with atomic mean-field spin–orbit integrals (the X2CAMF scheme). The contraction coefficients are taken from atomic X2CAMF Hartree–Fock spinors, thereby following the simple concept of a linear combination of atomic orbitals. Benchmark calculations of spin–orbit splittings, equilibrium bond lengths, and harmonic vibrational frequencies demonstrate the accuracy and efficacy of the j-adapted spin–orbit contraction scheme.
A discontinuous cavitation model (DCM)
Authors: Zheng Jun , Gu Yuanyuan , Wei Yingjie , Chen Weiqi , Li Changfeng , Han Xinyue , Wang Zhentao
Published: August 2024

A discontinuous cavitation model (DCM) containing the effects of ambient overpressure, incondensable gas, inertia, viscosity, surface tension, characteristic nuclei size, and characteristic surface speed of cavitation nuclei was proposed based on two approximate local first integrals of the Rayleigh–Plesset equation. Discontinuities caused by sudden cavitation bursting, heterogeneous nuclei distribution, and bubble-induced turbulence can, thus, be roughly represented. It was employed in simulating kinds of cavitation flows. It presented more physical reasonability than the Singhal model (SM) in capturing the vigorous vaporization in the water pool under strong negative ambient pressure. As for hydrodynamic cavitation around the National Advisory Committee for Aeronautics hydrofoil NACA0015, not only large-scale features were obtained as well as the SM, but also, some small-scale structures in the cavitation cloud were presented. For instance, isolated bubbles and their dynamic behaviors, such as inception and collapse, expansion and shrinkage, and breakup and coalescence, were captured. Extra turbulence pulsation, which is correlated with the temporal–spatial distribution of vapor concentration, can also be observed in the cavitation cloud. Moreover, different from the vorticity field obtained by the SM, the surface of the cavitation cloud obtained by the DCM becomes a thick vortex sheet. Moreover, another simulation case with a cavitation number of 0.32 further confirmed its adaptivity in supercavitation flows. Furthermore, by adjusting the parameters (i.e., the fluid density in the phase change layer near the cavitation nucleus) in the DCM, oscillations and waves excited by fierce phase change can be observed in cavitation clouds.
Quasi-critical dynamics in large-scale social systems regulated by sudden events
Authors: Guo Peng , Xu Yunhui , Guo Shichun , Tian Yang , Sun Pei
Published: August 2024

How do heterogeneous individual behaviors arise in response to sudden events and how do they shape large-scale social dynamics? Based on a five-year naturalistic observation of individual purchasing behaviors, we extract the long-term consumption dynamics of diverse commodities from approximately 2.2 million purchase orders. We subdivide the consumption dynamics into trend, seasonal, and random components and analyze them using a renormalization group. We discover that the coronavirus pandemic, a sudden event acting on the social system, regulates the scaling and criticality of consumption dynamics. On a large time scale, the long-term dynamics of the system, regardless of arising from trend, seasonal, or random individual behaviors, is pushed toward a quasi-critical region between independent (i.e., the consumption behaviors of different commodities are irrelevant) and correlated (i.e., the consumption behaviors of different commodities are interrelated) phases as the pandemic erupts. On a small time scale, short-term consumption dynamics exhibits more diverse responses to the pandemic. While the trend and random behaviors of individuals are driven to quasi-criticality and exhibit scale-invariance as the pandemic breaks out, seasonal behaviors are more robust against regulations. Overall, these discoveries provide insights into how quasi-critical macroscopic dynamics emerges in heterogeneous social systems to enhance system reactivity to sudden events while there may exist specific system components maintaining robustness as a reflection of system stability.
Vibrational relaxation of HOD by collisions with Ar atoms
Authors: Butkovskaya N. I. , Setser D. W.
Published: August 2024

Vibrational relaxation of HOD(v12, v3) molecules by collisions with Ar was studied at 298 K (v12 denotes coupled bending, v2, and OD stretching, v1, vibrational modes and v3 denotes OH stretching mode). The vibrationally excited HOD molecules were generated by exothermic abstraction reactions of OD radicals with 13 different RH reactants and observed by infrared emission from a fast-flow reactor as a function of Ar pressure and reaction time. State-specific relaxation rate constants were obtained by comparison of the time evolution of the experimental vibrational distributions with numerical kinetic calculations for vibrational populations. The relaxation mechanism was based on the relaxation scheme of H2O studied earlier with the addition of specific channels for HOD(v12, v3). Unlike H2O, energy in stretching and bending vibrations of HOD cannot be separated due to close ν1 and 2ν2 energies, which leads to fast collisional equilibration between these Fermi-resonant levels. For relaxation of the only pure bending state (10), a rate constant of (1.5 ± 0.3) × 10−13 cm3 molecule−1 s−1 was obtained. The relaxation rate of higher v12 states linearly increases with quantum number and very likely includes transfer of population from OD stretch levels, v1, to a lower energy bend level. The average rate constants for the loss of population from (01), (02), and (03) stretching states are (1.1 ± 0.3) × 10−14, (3.2 ± 1.0) × 10−14, and (5.6 ± 1.2) × 10−14 cm3 molecule−1 s−1, respectively.
Identifying divertor detachment using a machine learning model trained on divertor camera images from DIII-D
Authors: Victor B. S. , Scotti F.
Published: August 2024

This paper describes the application of a machine learning (ML) algorithm using a convolution neural network, first developed in Boyer et al. [“Classification and prediction of detachment in DIII-D using neural networks trained on C III imaging,” Nucl. Fusion (submitted) (2024)], to detect divertor detachment in DIII-D. Detachment detection is based on images from tangentially viewing upper and lower filtered divertor cameras that measure CIII emission at 465 nm. Separate ML models are developed for lower single null and upper single null configurations with mostly closed divertor shapes. Due to the viewing angle and divertor geometry, camera images of the upper divertor show a stark contrast in CIII emission between attached and detached conditions and the model identified detachment with 100% accuracy in the test dataset. For the lower divertor images, the contrast between attached and detached conditions is lower and the model identifies detachment with 96% accuracy. This ML model will be applied to the image data after each shot to provide a rapid assessment of divertor detachment to aid operation of DIII-D with the potential extension to other devices in the future.
Kylin-V: An open-source package calculating the dynamic and spectroscopic properties of large systems
Authors: Xu Yihe , Liu Chungen , Ma Haibo
Published: August 2024

Quantum dynamics simulation and computational spectroscopy serve as indispensable tools for the theoretical understanding of various fundamental physical and chemical processes, ranging from charge transfer to photochemical reactions. When simulating realistic systems, the primary challenge stems from the overwhelming number of degrees of freedom and the pronounced many-body correlations. Here, we present Kylin-V, an innovative quantum dynamics package designed for accurate and efficient simulations of dynamics and spectroscopic properties of vibronic Hamiltonians for molecular systems and their aggregates. Kylin-V supports various quantum dynamics and computational spectroscopy methods, such as time-dependent density matrix renormalization group and our recently proposed single-site and hierarchical mapping approaches, as well as vibrational heat-bath configuration interaction. In this paper, we introduce the methodologies implemented in Kylin-V and illustrate their performances through a diverse collection of numerical examples.