bluuebunny/crossref_metadata_2025_split huggingface dataset:
Conceptual Analysis on the Impact of Acoustic Liners in Fan Flutter
Authors: González-Monge Javier , Pérez José Miguel , Corral Roque , Zhao Fanzhou , Vahdati Mehdi 
Published: August 2024

Abstract
This work investigates the impact of acoustically treated intakes on fan flutter. The propagation of the fan acoustic perturbations is studied using a simplified model, where the frequency of the waves in the intake is the natural frequency of the fan blade in the stationary frame of reference. The model consists of a constant cross-section annular duct, where the acoustic modes are computed for hard wall and lined wall regions, assuming a uniform axial flow. The interfaces between the lined and hard wall sections are solved by doing mode matching. The acoustic reflections in the zero-thickness intake are computed using the WienerHopf technique following Rienstra’s model. Analytical results show that the waves propagating from the fan are reflected and scattered radially at the interfaces between the hard wall and the liner. Furthermore, the liner damps and changes the phase velocity of acoustic modes. Due to the low frequency of the flutter waves, the radial scattering can activate different cut-off modes, which need to be retained in order to make accurate predictions. The likelihood of fan flutter is estimated using the phase of the reflected cut-on waves reaching the fan. This strategy is used to assess the impact of the acoustic liners on the stability of a realistic fan. It is concluded that the impact of the phasing and reflections induced by the acoustic liners is comparable to that of the intake and can alter the flutter characteristics of the fan significantly.
The Effect of Temperature on the Forced Response of a Blisk Rotor With Inherent Mistuning
Authors: Dodda Jhansi , Leng Yujun , Key Nicole L. 
Published: August 2024

Abstract
Rotor forced response is a major cause of high-cycle fatigue (HCF) in gas turbine engines. Blade-to-blade variations in natural frequency, known as mistuning, can cause significant variations in the blade-to-blade vibrational response. Individual blade resonant response, primarily the peak frequency, has been used as a ‘fingerprint’ to identify a rotor blisk, and the change in frequency is widely used as a failure detection technique.
The frequency data from a forced response investigation of an embedded rotor in the Purdue 3-stage axial compressor research facility is the focus of this work. The forced response of the embedded rotor was measured with both strain gauge and blade tip timing systems. During a repeatability study of the vibrational response, a notable shift in blade peak response frequency was observed. Despite a shift in the peak frequency, the overall shape of the individual blade resonant response curve remained similar, even with the inherent mistuning of the rotor. Factors affecting the frequency and dynamic response were investigated to address this shift.
A major difference between these tests was the ambient temperature, which was different on different days and at different times of the day. Material properties are generally temperature-dependent, which has the potential to change natural frequencies. A cyclic symmetric FEM modal analysis showed a modal frequency shift at different temperatures. An analytical study was conducted based on the Fundamental Mistuning Model, considering the effect of temperature. The analytical results correlate well with the experimental results, showing similar blade peak response shifts without significantly changing the blade resonant response curve for the considered temperature range.
Ignition Characteristics of Fully Premixed Hydrogen/Air and Methane/Air Flames With High-Speed Chemiluminescence and Schlieren Imaging
Authors: Tiwari Pratik , Premchand C. P. , Palies Paul 
Published: August 2024

Abstract
This article investigates the ignition of hydrogen/air and methane/air premixed flames in a laboratory scale experiment. It focuses on an initial characterization of the ignition transient sequence comparing the effects of fuel, equivalence ratio, and bulk velocity as well as geometry (bluff-body vs swirler, confined or unconfined). Transient evolution of the flame through high-speed flame chemiluminescence imaging are recorded for selected pre-mixture injector bulk velocities ranging from 5 to 15 m/s in the lean equivalence ratio range. Additional high-speed data include schlieren imaging. The chemiluminescence data are utilized to generate integrated flame light time-series to estimate ignition delay time. A comparison of the experimentally determined ignition delay time is conducted with results from literature and chemical kinetic data. The observed differences are discussed. Results from the high-speed schlieren imaging at speed up to 140 000 frames per second (fps) capturing the spark ignition dynamic sequence are documented next for three specific cases. These selected ignition transient sequences leading to stabilized flames are characterized in the premixed turbulent combustion flamelet regime near unity Karlovitz number. The flame front is tracked by identifying flame edges as the flame surface expands during the earliest instants of the ignition sequence. The method documented in this article is an initial step that can be used in future work to describe the evolution from ignition to flame stabilization. This work is motivated to fill the gap on ignition studies in the fully premixed regime and especially for hydrogen/air premixture where spark igniter is utilized.
Aerodynamic Study of a Horizontal Axis Wind Turbine in Surge Motion Under Angular Speed and Blade Pitch Controls
Authors: Firpo Agnese , Sanvito Andrea G. , Dossena Vincenzo , Persico Giacomo 
Published: August 2024

Abstract
Floating offshore wind turbines experience dynamic conditions due to platform motion, requiring specific control strategies to mitigate loads and promote the wake diffusion improving overall wind farm efficiency. These problems can be appropriately modelled by medium-fidelity solvers, which rely on a CFD resolution of the flow while avoiding its detailed resolution around the blades, preserving high-fidelity in simulating the wake at an acceptable computational cost. This work adopts a medium-fidelity Actuator Line Model, implemented in the OpenFOAM environment, previously validated against experiments and multi-fidelity models in the frame of the OC6 Phase III project. The study analyses several operating conditions during surge motion: a variable angular speed in below-rated condition, conceived to maximise the turbine efficiency, and a collective blade pitch control employable in above-rated conditions to limit surge-induced loads fluctuations. The effect of each control strategy is assessed individually through a systematic comparison with the baseline case with constant angular speed and blade pitch. Results indicate that the angular speed control succeeds in increasing the turbine power, and reduces the spanwise variability of the induction factor amplitudes. Conversely, the pitch angle control reduces the force amplitude but does not alter the spanwise trend of the induction factor amplitude.
Design and Analysis of High-Temperature, High-Pressure Seal Test Rig
Authors: Kerr Thomas , Bensmiller Jason 
Published: August 2024

Abstract
As the power density of turbomachinery increases, individual components such as seals are subject to more extreme conditions. The maximum working fluid temperature and pressure are increasing, as is the operating speed. Seal performance has always had a large impact on machine efficiency, but with new working fluids and higher temperatures, this is especially true. Designing component level test rigs at these conditions presents challenges. Material compatibility at high temperatures, rotordynamics, thermal expansion, and a cooling scheme must be balanced in order to yield satisfactory designs.
This paper presents the design of a new test rig capable of testing seals to 700° C and 250 bar at speeds up to 21,000 rpm. The test rig measures leakage and estimates drag loss. While designed to test dry gas seals for sCO2, the test rig can accommodate a variety of seal types, geometries, and working fluids. A direct drive 250 kW motor provides rotation to the test rig, and a separate spindle assembly provides a connection to ground. Thermal expansion in the seal housing is radially uniform due to a flexible attachment to the spindle assembly. The seal housing material is Alloy 625, and is rated for the full pressure range. Cooling is provided to the spindle shaft through an oil/air system.
Systems-Based Approach to Predicting TBC Delamination due to CMAS Infiltration
Authors: Teglas Matei , Bojdo Nicholas , Elms Jacob , Pawley Alison , Covey-Crump Stephen , Jones Merren 
Published: August 2024

Abstract
CMAS infiltration and attack is difficult to simulate at real-world rates. To better understand the sensitivity of the process to engine operating parameters and CMAS chemical composition, a systems-based reduced order infiltration model that incorporates combustion gas properties, TBC microstructural properties, TBC heat transfer properties, and CMAS physical properties was developed. The aim was to predict the time to delamination for aircraft engines operating in non-benign environments. The penetration depths reached by a synthetic four-element CMAS mixture within a clean TBC were calculated by finite difference method. Engine operating conditions and TBC top coat types were varied to study the effects on the penetration depths and times. A larger difference between operating temperature and cold shock temperature was found to increase the risk of Mode I delamination. An increase in engine operating temperature had little effect on the critical penetration depth, but significantly influenced the actual penetration depth and time. An increase in EB-PVD TBC taper angle resulted in a decrease in the critical penetration depths, suggesting a greater risk of Mode I delamination. The time taken to reach the actual penetration depth increased with operating time, until the TBC was consumed, at which point penetration time decreased with operating temperature due to lower melt viscosity.
Model for Local Cavitation Instabilities in 2-Bladed Turbopump Inducers
Authors: Yoon Youngkuk , Song Seung Jin 
Published: August 2024

Abstract
Various local cavitation instabilities in turbopump inducers (e.g., alternate blade cavitation, super-synchronous rotating cavitation, etc.) have previously been experimentally identified. However, a model, which is capable of predicting such local instabilities is still lacking. Therefore, a new model, which models an N-bladed inducer as a system of N coupled mass-spring-damper systems, is presented to predict post-onset behavior of alternate blade cavitation instabilities. The model predicts alternate blade cavitation to occur. As the flow coefficient is decreased, the model predicts the magnitude of alternate blade cavitation to first increase and then decrease, and then finally vanish. If the flow coefficient is further decreased beyond the range of alternate blade cavitation, sudden increase in equilibrium incidence is predicted. All of these predictions agree with the previous experimental findings. Furthermore, simultaneous in-phase oscillations of the blade cavities are predicted during alternate blade cavitation. These in-phase oscillations of the cavities correspond to the surge mode oscillation, which had been previously mistakenly categorized as a global (system) instability. Finally, it is proposed that the above post-onset behaviors of alternate blade cavitations are general in two-bladed inducers, as long as the change in incidence on the following blade has a local minimum when it is expressed as a function of leading blade’s incidence.
Osteomyelitis-relevant antibiotics at clinical concentrations show limited effectivity against acute and chronic intracellular
S. aureus
infections in osteocytes
Authors: Zelmer Anja R. , Yang Dongqing , Gunn Nicholas J. , Solomon L. Bogdan , Nelson Renjy , Kidd Stephen P. , Richter Katharina , Atkins Gerald J. 
Published: August 2024

ABSTRACT

Osteomyelitis caused by
Staphylococcus aureus
can involve the persistent infection of osteocytes. We sought to determine if current clinically utilized antibiotics were capable of clearing an intracellular osteocyte
S. aureus
infection. Rifampicin, vancomycin, levofloxacin, ofloxacin, amoxicillin, oxacillin, doxycycline, linezolid, gentamicin, and tigecycline were assessed for their minimum inhibitory concentration (MIC) and minimum bactericidal concentrations against 12
S. aureus
strains, at pH 5.0 and 7.2 to mimic lysosomal and cytoplasmic environments, respectively. Those antibiotics whose bone estimated achievable concentration was commonly above their respective MIC for the strains tested were further assayed in a human osteocyte infection model under acute and chronic conditions. Osteocyte-like cells were treated at 1×, 4×, and 10× the MIC for 1 and 7 days following infection (acute model), or at 15 and 21 days of infection (chronic model). The intracellular effectivity of each antibiotic was measured in terms of CFU reduction, small colony variant formation, and bacterial mRNA expression change. Only rifampicin, levofloxacin, and linezolid reduced intracellular CFU numbers significantly in the acute model. Consistent with the transition to a non-culturable state, few if any CFU could be recovered from the chronic model. However, no treatment in either model reduced the quantity of bacterial mRNA or prevented non-culturable bacteria from returning to a culturable state. These findings indicate that
S. aureus
adapts phenotypically during intracellular infection of osteocytes, adopting a reversible quiescent state that is protected against antibiotics, even at 10× their MIC. Thus, new therapeutic approaches are necessary to cure
S. aureus
intracellular infections in osteomyelitis.
Respiratory syncytial virus infection provides protection against severe acute respiratory syndrome coronavirus challenge
Authors: Hartwig Stacey M. , Odle Abby , Wong Lok-Yin Roy , Meyerholz David K. , Perlman Stanley , Varga Steven M. 
Published: August 2024

ABSTRACT

Respiratory infections are a major health burden worldwide. Respiratory syncytial virus (RSV) is among the leading causes of hospitalization in both young children and older adults. The onset of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic and the public health response had a profound impact on the normal seasonal outbreaks of other respiratory viruses. However, little is known about how a prior respiratory virus infection impacts SARS-CoV-2 disease outcomes. In this study, we examine the impact of a previous RSV infection on the disease severity of a subsequent SARS-CoV-2 challenge in BALB/c mice. Mice infected with RSV, followed by a SARS-CoV-2 challenge, 30 days later, exhibited decreased weight loss and increased survival as compared to control groups. Our results suggest a prior RSV infection can provide protection against a subsequent SARS-CoV-2 infection.

IMPORTANCE
Severe acute respiratory syndrome coronavirus 2 and respiratory syncytial virus are respiratory viruses that are a major health burden worldwide. Severe acute respiratory syndrome coronavirus 2 and respiratory syncytial virus frequently have peak seasonal outbreaks during the winter months, and are capable of causing severe respiratory disease, often leading to hospitalization. The 2019 pandemic brought attention to the importance of understanding how co-circulating viruses can impact the disease severity of other respiratory viruses. It is known that many hospitalized patients are undergoing multiple viral infections at once, yet not much has been studied to understand the impact this has on other respiratory viruses or patients. How co-circulating viruses impact one another can provide critical knowledge for future interventions of hospitalized patients and potential vaccination strategies.
Host WD repeat-containing protein 5 inhibits protein kinase R-mediated integrated stress response during measles virus infection
Authors: BenDavid Ethan , Yang Chuyuan , Zhou Yuqin , Pfaller Christian K. , Samuel Charles E. , Ma Dzwokai 
Published: August 2024

ABSTRACT

Some negative-sense RNA viruses, including measles virus (MeV), share the characteristic that during their infection cycle, cytoplasmic inclusion bodies (IBs) are formed where components of the viral replication machinery are concentrated. As a foci of viral replication, how IBs act to enhance the efficiency of infection by affecting virus-host interactions remains an important topic of investigation. We previously established that upon MeV infection, the epigenetic host protein, WD repeat-containing protein 5 (WDR5), translocates to cytoplasmic viral IBs and facilitates MeV replication. We now show that WDR5 is recruited to IBs by forming a complex with IB-associated MeV phosphoprotein via a conserved binding motif located on the surface of WDR5. Furthermore, we provide evidence that WDR5 promotes viral replication by suppressing a major innate immune response pathway, the double-stranded RNA-mediated activation of protein kinase R and integrated stress response.

IMPORTANCE
MeV is a pathogen that remains a global concern, with an estimated 9 million measles cases and 128,000 measles deaths in 2022 according to the World Health Organization. A large population of the world still has inadequate access to the effective vaccine against the exceptionally transmissible MeV. Measles disease is characterized by a high morbidity in children and in immunocompromised individuals. An important area of research for negative-sense RNA viruses, including MeV, is the characterization of the complex interactome between virus and host occurring at cytoplasmic IBs where viral replication occurs. Despite the progress made in understanding IB structures, little is known regarding the virus-host interactions within IBs and the role of these interactions in promoting viral replication and antagonizing host innate immunity. Herein we provide evidence suggesting a model by which MeV IBs utilize the host protein WDR5 to suppress the protein kinase R-integrated stress response pathway.
Breast milk induces the differentiation of monocytes into macrophages, promoting human cytomegalovirus infection
Authors: Cai Xiaodan , Padilla Nicole T. , Rosbe Kristina , Tugizov Sharof M. 
Published: August 2024

ABSTRACT

Human cytomegalovirus (HCMV) is a ubiquitous herpesvirus found in human breast milk that is frequently transmitted from HCMV-seropositive mothers to their infants during the postnatal period. Despite extensive research, the mechanisms underlying HCMV transmission from breast milk and the anatomical location at which virus transfer takes place remain unclear. Breast milk contains many uniquely differentiated macrophages that undergo specific morphological and functional modifications in the mammary gland during lactation. Although the existence of permissive HCMV infection in differentiated macrophages has been well-described, the role of breast milk in this process remains unknown. Herein, we report that exposure of isolated peripheral blood monocytes to breast milk induces their differentiation into macrophages that exhibit an M2 phenotype (CD14
high
CD163
high
CD68
high
CD206
high
) and promotes a productive and sustained HCMV infection. We also found that breast milk triggers macrophage proliferation and thus sustains a unique population of proliferating, long-lived, and HCMV-susceptible macrophages that are capable of ongoing production of infectious virions. These results suggest a mechanism that explains chronic HCMV shedding into the breast milk of postpartum seropositive mothers. We also found that HCMV virions released from breast milk-induced macrophages generate a productive infection in primary infant tonsil epithelial cells. Collectively, our results suggest that breast milk may facilitate HCMV transmission from mother to infant via the oropharyngeal mucosa.

IMPORTANCE
While human cytomegalovirus (HCMV) is frequently detected in the breast milk of HCMV-seropositive women and is often transmitted to infants via breastfeeding, the mechanisms by which this transmission occurs remain unclear. In this study, we modeled HCMV transmission at the oropharyngeal mucosa. We treated human monocytes with breast milk to mimic the lactating mammary gland microenvironment. We found that monocytes differentiated into macrophages with an M2 phenotype, which were highly permissive for HCMV. We also discovered that breast milk induces macrophage proliferation. Thus, exposure to breast milk increased the number of HCMV-susceptible macrophages and supported high levels of infectious HCMV. We found that HCMV virions released from breast milk-induced macrophages could infect primary infant tonsil epithelial cells. Collectively, these findings reveal the dual role of breast milk that induces the differentiation and proliferation of macrophages in the mammary gland and thus facilitates mother-to-child HCMV transmission at the oropharyngeal mucosa.
Draft genome sequences of
Butyrivibrio hungatei
DSM 14810 (JK 615
T
) and
Butyrivibrio fibrisolvens
DSM 3071 (D1
T
)
Authors: Berner Keely , Zoza-Veloz Michelle , Nolan Matt , Graham Danielle , Ivanova Natalia , Seshadri Rekha , Spring Stefan , Escobar Matthew 
Published: August 2024

ABSTRACT

Here, we report the draft genome sequences of two
Butyrivibrio
-type strains isolated from rumen fluid. The genome sequence of
Butyrivibrio hungatei
DSM 14810 was 3.3 Mb with 3,093 predicted genes, while the
Butyrivibrio fibrisolvens
DSM 3071 genome sequence was 4.8 Mb with 4,132 predicted genes.