bluuebunny/crossref_metadata_2025 huggingface dataset:
Determinants of successful opioid deprescribing: Insights from French pain physicians—A qualitative study
Authors: Nizet Pierre , Deme Laure , Evin Adrien , Kuhn Emmanuelle , Nizard Julien , Victorri Vigneau Caroline , Huon Jean‐François
Published: August 2024

Background

Long‐term use of opioids does not result in significant clinical improvement and has shown more adverse than beneficial effects in chronic pain conditions. When opioids cause more adverse effects than benefits for the patient, it may be necessary to initiate a process of deprescribing.

Aim

To explore the perceptions of French pain physicians regarding the process of opioid deprescribing in patients experiencing chronic non‐cancer and to generate an understanding of the barriers and levers to the deprescribing process.

Methods

We conducted a multicentric observational study with qualitative approach. Individual semi‐structured interviews exploring pain physicians' perceptions, beliefs, and representations to assess the determinants of opioid deprescribing with an interview guide were used. After checking the transcripts, an inductive and independent thematic analysis of the interviews was to extract meaningful themes from the dataset.

Results

Twelve pain physicians were interviewed. The main obstacles to deprescribing revolved around patient‐specific attributes, characteristics of the opioids themselves, and limitations within the current healthcare system, that hinder optimal patient management. Conversely, patient motivation and education, recourse to hospitalization in a Pain Department with multidisciplinary care, follow‐up by the general practitioner, and training and information dissemination among patients and clinicians emerged as facilitative elements for opioid deprescribing.

Conclusion

This study underscores the needs to improve the training of healthcare professionals, the effective communication of pertinent information to patients, and the establishment of a therapeutic partnership with the patient. It is therefore essential to carry out the deprescribing process in a collaborative and interprofessional manner, encompassing both pharmaceutical and non‐pharmaceutical strategies.
Parent experiences during delivery, postpartum, and adoption of children with congenital melanocytic nevi
Authors: Kozina Yuliya , Williams Kendrick J. , Politi Mary C. , Frieden Ilona J. , Coughlin Carrie C.
Published: August 2024

Background/Aims

Congenital melanocytic nevi (CMN) are often unexpected discoveries at time of childbirth or adoption. Understanding how parents/guardians cope with these visible birthmarks can help clinicians better care for children and their families. Using qualitative methods, we sought to categorize early family responses to CMN and identify approaches to better engage with parents early in their child's life.

Methods

Semi‐structured interviews were conducted within a broader study on shared decision making for families with children with CMN. Discussions included information on birth and early life experiences. Data was dual‐coded, inductively and deductively, and analyzed with the Parker and Endler framework exploring emotion‐, task‐, and avoidance‐oriented coping.

Results

Fifteen parents of 13 children were interviewed. Parents described all three categories of coping. Emotions ranged from guilt, to neutrality, to positive responses seeing their child's CMN. Stress was lower in families with prior knowledge of CMN. Dermatology referral provided an opportunity for learning, but also triggered worry for some families.

Conclusions

Parents process and react to the diagnosis of CMN with a range of emotions and coping styles. Dermatologists can utilize open‐ended questions to understand family emotions and provide families with tailored knowledge and resources. Early discussion of the diagnosis and family education are important support tools.
In case of emergency break glass: Reckoning with Project 2025
Authors: LaBarca Vincent
Published: August 2024

Public health nursing frequently finds itself at the nexus of community and politics. It is a precarious position, one that demands a keen understanding of how decisions made in the halls of power impact the most vulnerable among us. From gutting Medicaid and TANF to eroding protections for LGBTQ individuals and female‐headed households, Project 2025 is an affront to public health nursing's moral foundation and professional ethos. This personal reflection challenges nurses to embrace their role as advocates for a more just and equitable society.
Breast cancer during pregnancy of Luminal A type overexpressed CXCL13
Authors: Nozaki Fumi , Nakanishi Yoko , Tanino Tomoyuki , Ochi Tomohiro , In Reika , Kajiura Yuka , Kida Kumiko , Takei Junko , Yoshida Atsushi , Kanomata Naoki , Kitano Atsuko , Yamauchi Hideko , Masuda Shinobu
Published: August 2024

Pregnancy‐associated breast cancer has been increasing. In this study, we analyzed patients with breast cancer that occurred during pregnancy (PrBC) and compared their genetic profiles with those of patients with breast cancer that did not occur during pregnancy, within 1 year after childbirth nor during lactation (non‐PrBC). We performed gene expression analyses of patients with PrBC and non‐PrBC using microarrays and qRT‐PCR. Microarray analysis showed that 355 genes were upregulated in the luminal‐type PrBC group compared to those in the non‐PrBC group. The C‐X‐C motif chemokine ligand 13 (CXCL13) gene was the most upregulated in the PrBC group compared to that in the non‐PrBC group, especially in the luminal A‐type (p = 0.016). This result was corroborated by the qRT‐PCR analysis of microdissected cancer cells (p < 0.001). A negative correlation was observed between CXCL13 and estrogen receptor 1 (ESR1) mRNA expression levels in luminal A‐type breast carcinoma (p < 0.001). Our results provide clues for a better understanding of breast cancer pathogenesis during pregnancy.
HcLEA113, a late embryogenesis abundant protein gene, positively regulates drought‐stress responses in kenaf
Authors: Luo Dengjie , Wang Caijin , Mubeen Samavia , Rehman Muzammal , Cao Shan , Yue Jiao , Pan Jiao , Jin Gang , Li Ru , Chen Tao , Chen Peng
Published: August 2024

Late embryogenesis abundant (LEA) proteins have been widely recognized for their role in various abiotic stress responses in higher plants. Nevertheless, the specific mechanism responsible for the function of LEA proteins in plants has not yet been explored. This research involved the isolation and characterization of HcLEA113 from kenaf, revealing a significant increase in its expression in response to drought stress. When HcLEA113 was introduced into yeast, it resulted in an improved survival rate under drought conditions. Furthermore, the overexpression of HcLEA113 in tobacco plants led to enhanced tolerance to drought stress. Specifically, HcLEA113‐OE plants exhibited higher germination rates, longer root lengths, greater chlorophyll content, and higher relative water content under drought stress compared to wild‐type (WT) plants, while their relative conductivity was significantly lower than that of WT plants. Further physiological measurements revealed that the proline content, soluble sugars, and antioxidant activities of WT and HcLEA113‐OE tobacco leaves increased significantly under drought stress, with greater changes in HcLEA113‐OE plants than WT. The increase in hydrogen peroxide (H2O2), superoxide anions (O2−), and malondialdehyde (MDA) content was significantly lower in HcLEA113‐OE lines than in WT plants. Additionally, HcLEA113‐OE plants can activate reactive oxygen species (ROS)‐ and osmotic‐related genes in response to drought stress. On the other hand, silencing the HcLEA113 gene through virus‐induced gene silencing (VIGS) in kenaf plants led to notable growth suppression when exposed to drought conditions, manifesting as decreased plant height and dry weight. Meanwhile, antioxidant enzymes' activity significantly decreased and the ROS content increased. This study offers valuable insights for future research on the genetic engineering of drought resistance in plants.
Uptake and engagement of a clinically moderated digital peer support platform to support the mental well‐being older adults: a qualitative investigation
Authors: Wilson Jessica , Heinsch Milena , Tickner Campbell , Speirs Bronte , Wells Hannah , Kay‐Lambkin Frances
Published: August 2024

Background

The uptake of traditional mental health services among older adults remains low. Digital peer support offers older adults a resource for engaging with others to independently support their mental well‐being. This qualitative study explored the uptake and engagement of a clinically moderated digital peer support platform (Breathing Space) for older adults with depressive symptoms and alcohol use concerns.

Methods

Semi‐structured interviews with 30 participants aged 60–80 years explored participants' uptake and engagement with Breathing Space, a novel, moderated, private, and anonymous peer support platform. Data were analysed using reflective thematic analysis and are discussed with reference to the Unified Theory of Acceptance and Use of Technology2.

Results

Three themes were constructed to characterize participants' experiences: (i) navigating the complexities of peer‐peer online engagement; (ii) the function of anonymity in online connection; and (iii) experiences of app features and content.

Conclusions

Future development of digital peer support for older adults would benefit from the following: (i) co‐design with older adults; (ii) providing choice over anonymity and increased options for interacting with peers; (iii) streamlining the basic functionality with popular platforms; (iv) providing options for users to curate their digital experience; and (v) providing telephone support for troubleshooting technical difficulties. Future research should explore the use of digital peer support among older adults who experience social exclusion challenges.
School absence legislation governing in Norway, Sweden and Denmark for children with chronic illness in compulsory education—A comparative study
Authors: Skoubo Sofie , Handberg Charlotte , Weibel Mette , Larsen Hanne Bækgaard
Published: August 2024

Background

Health and education are interrelated and influence social, economic and lifestyle perspectives. Children with chronic illnesses experience barriers in the educational system regarding school attendance and social isolation. Gaining knowledge of compulsory education and how children with chronic illnesses are supported is crucial for the implications of future education policy and legislation in Scandinavia. This study compares Scandinavian legislation frameworks on compulsory education, chronic illness and school absence to form the basis of future research on education for children with chronic illness.

Methods

The study uses a comparative approach to explore the support of children with chronic illnesses in compulsory education across Norway, Sweden and Denmark. The documents included are 3 education acts and 15 secondary documents, which are notes and guidelines for the education acts. The data were analysed using a manifest content analysis.

Findings

We found four categories and six subcategories: (1) school obligation and rights; (2) chronic illness; (3) school absence: (a) categorisation of absence; (b) registration of absence; and (c) sanction; and (4) education support: (a) Hospital school support; (b) Home instruction support; and (c) technological support.

Conclusion

This study's findings demonstrate the similarities and differences in the Scandinavian compulsory education legislation and guidelines regarding chronic illness and school absence. We found similarities across the countries regarding chronic illness and school absence. Still, the findings showed differences in the systematic registration of school absence and requirements for attendance with compulsory education in Norway and Denmark compared with compulsory schooling in Sweden. This knowledge will inform and enlighten future discussions and decisions in education and public health. The results can contribute to awareness of the opportunities for educational support and perspectives about education for children with chronic illnesses. Future research focusing on the experience of children with chronic illness and educational support is needed.
The causal relationship between immune cells and atopic dermatitis: A bidirectional Mendelian randomization study
Authors: Zhu Xu , Wu Wenzhong
Published: August 2024

Background

Atopic dermatitis (AD) is a chronic inflammatory skin condition whose origins remain unclear. Existing epidemiological evidence suggests that inflammation and immune factors play pivotal roles in the onset and progression of AD. However, previous research on the connection between immune inflammation and AD has yielded inconclusive results.

Methods

To evaluate the causal relationship between immunological characteristics and AD, this study employed a bidirectional, two‐sample Mendelian randomization (MR) approach. We utilized large‐scale, publicly available genome‐wide association studies to investigate the causal associations between 731 immunological feature cells and the risk of AD.

Results

Significant associations were identified between six immune phenotypes and AD risk: increased Basophil %CD33dim HLA DR−CD66b−, CD25 on IgD+ CD24+, CD40 on monocytes, HLA DR on CD14+ CD16−monocytes, HLA DR on CD14+monocytes correlated with higher AD risk, while elevated CD3 on CD4 Treg was linked to lower risk. Reverse MR analysis revealed AD as a risk factor for IgD+ CD38br AC and IgD+ CD38br %B cell, but a protective factor against CD20 on IgD+ CD38− naive and CD8 on NKT.

Conclusion

Our findings elucidate the intricate interplay between immune cells and AD, informing future research into AD pathophysiology and therapeutics.
Apparent Joint Swarms Formed by the Crack‐Jump Process
Authors: Peacock D. C. P. , Leiss B. , Anderson M. W.
Published: August 2024

Joint swarms can be important components of fractured reservoirs. They are often explained as damage around faults or related to mechanical differences between layers, although this does not explain the close spacing of the joints. Joint swarms around Bergen (Norway) are described, which are not related to exposed faults and are not influenced by layering or foliation in the Lower Palaeozoic gneisses. We suggest an evolution whereby: (1) a zone of microcracks develops; (2) one microcrack propagates and becomes connected to a source of mineralising fluid; (3) the fracture becomes a microvein, with a higher tensile strength than the microcracked host rock; (4) another microcrack propagates and the cycle is repeated, producing a zone of microveins; (5) the veins are partly weathered out, producing an apparent joint swarm, or the microveins crack at or near the ground‐surface. Joint swarms in exposed analogues may therefore not occur at reservoir depths.
The definable content of homological invariants I: Ext$\mathrm{Ext}$ and lim1$\mathrm{lim}^1$
Authors: Bergfalk Jeffrey , Lupini Martino , Panagiotopoulos Aristotelis
Published: August 2024

This is the first installment in a series of papers illustrating how classical invariants of homological algebra and algebraic topology may be enriched with additional descriptive set theoretic information. To effect this enrichment, we show that many of these invariants may be naturally regarded as functors to the category, introduced herein, of groups with a Polish cover. The resulting definable invariants provide far stronger means of classification. In the present work we focus on the first derived functors of and . The resulting definable for pairs of countable abelian groups and definable for towers of Polish abelian groups substantially refine their classical counterparts. We show, for example, that the definable is a fully faithful contravariant functor from the category of finite‐rank torsion‐free abelian groups with no free summands; this contrasts with the fact that there are uncountably many non‐isomorphic such groups with isomorphic classical invariants . To facilitate our analysis, we introduce a general Ulam stability framework for groups with a Polish cover; within this framework we prove several rigidity results for non‐Archimedean abelian groups with a Polish cover. A special case of our main result answers a question of Kanovei and Reeken regarding quotients of ‐adic groups. Finally, using cocycle superrigidity methods for profinite actions of property (T) groups, we obtain a hierarchy of complexity degrees for the problem of classifying all group extensions of by up to base‐free isomorphism, when for prime numbers and .
Experiences of mental health practitioners after clients’ suicide: a qualitative systematic review protocol
Authors: Du Jian , Li Jiaoli , Kantor Jiří , Kabiri Neda , Svobodová Zuzana , Munn Zachary
Published: August 2024

Objective:

The objective of this qualitative systematic review is to understand the experiences of mental health practitioners after clients’ suicide.

Introduction:

Mental health practitioners inevitably encounter client suicide during their careers, which can significantly affect their personal lives and professional outcomes. A deeper understanding of mental health practitioners’ experiences in the aftermath of clients’ suicide is necessary to provide effective support and assist with adaptation to this situation.

Inclusion criteria:

This systematic review will consider qualitative studies that explore the experiences of mental health practitioners, including psychotherapists, psychiatrists, psychological counselors, clinical psychologists, psychiatric mental health nurse practitioners, and social workers following clients’ suicide. Experiences may include emotional responses, coping strategies, changes in social relationships, and reflections on practice.

Methods:

This review will follow the JBI methodology for qualitative systematic reviews. The databases to be searched will include PubMed, CINAHL (EBSCOhost), Embase, PsycINFO (EBSCOhost), SocINDEX (EBSCOhost), Web of Science, CNKI, Wanfang, VIP, Bibliographia Medica Čechoslovaca, and Bibliographia Medica Slovaca. Gray literature sources will include Google Scholar and ProQuest Dissertations and Theses. Studies in English, Czech, Slovak, and Chinese will be assessed for inclusion regardless of publication date. Studies that are initially selected will be assessed for methodological quality using the JBI critical appraisal tool for qualitative studies. Then, findings with illustrations will be extracted for subsequent meta-aggregation and ConQual assessment. All the above steps will be conducted by 2 independent reviewers.

Review registration:

PROSPERO CRD42023410523
Role of the peripheral chemoreceptors in cardiovascular and metabolic control in type 2 diabetes
Authors: Limberg Jacqueline K. , Ott Elizabeth P. , Pipkins Aubrey M. , Lis Eric C. , Gonsalves Anna M. , Harper Jennifer L. , Manrique‐Acevedo Camila
Published: August 2024

Preclinical work supports a role for the peripheral chemoreceptors in the progression of cardiovascular and metabolic pathologies. In the present study, we examined peripheral chemosensitivity in adults with type 2 diabetes (T2D) and the contribution of the peripheral chemoreceptors to resting cardiovascular and metabolic control. We hypothesized that: (1) adults with T2D exhibit exaggerated peripheral chemoreflex sensitivity; (2) the peripheral chemoreceptors contribute to cardiovascular dysfunction in T2D; and (3) attenuation of peripheral chemoreceptor activity improves glucose tolerance in T2D. Seventeen adults with diagnosed T2D [six males/11 females; aged 54 ± 11 years; glycated haemoglobin (HbA1c) 7.6 ± 1.5%] and 20 controls without T2D (9 males/11 females; aged 49 ± 13 years, HbA1c 5.2 ± 0.4%) participated in the study. The hypoxic ventilatory response (HVR) was assessed as an index of peripheral chemosensitivity. Resting heart rate, blood pressure and minute ventilation were measured when breathing normoxic followed by hyperoxic air (1.0) to acutely attenuate peripheral chemoreceptor activity. A subset of participants (n = 9 per group) completed two additional visits [normoxia (0.21), hyperoxia (1.0)] where glucose and insulin were measured for 2 h following an oral glucose challenge. HVR was augmented in adults with T2D (–0.84 ± 0.49 L min–1/%) vs. control (–0.48 ± 0.40 L min–1/%, P = 0.021). Attenuation of peripheral chemoreceptor activity decreased heart rate (P < 0.001), mean blood pressure (P = 0.009) and minute ventilation (P = 0.002); any effect of hyperoxia did not differ between groups. There was no effect of hyperoxia on the glucose (control, P = 0.864; T2D, P = 0.982), nor insulin (control, P = 0.763; T2D, P = 0.189) response to the oral glucose challenge. Peripheral chemoreflex sensitivity is elevated in adults with T2D; however, acute attenuation of peripheral chemoreflex activity with hyperoxia does not restore cardiometabolic function.

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Key points

Preclinical work supports a role for the peripheral chemoreceptors in the progression of cardiovascular and metabolic pathologies. In the present study, we examined peripheral chemosensitivity in adults with type 2 diabetes and the contribution of the peripheral chemoreceptors to resting cardiovascular control and glucose tolerance. We observed elevated peripheral chemoreflex sensitivity in adults with diabetes which was associated with glycaemic control (i.e. glycated haemoglobin). Notably, acute attenuation of peripheral chemoreflex activity with hyperoxia did not restore cardiometabolic function in the individuals studied.
Mitigating Crouch Gait With an Autonomous Pediatric Knee Exoskeleton in the Neurologically Impaired
Authors: Lee Dawit , Mulrine Sierra C. , Shepherd Max K. , Westberry David E. , Rogozinski Benjamin M. , Herrin Kinsey R. , Young Aaron J.
Published: August 2024

Crouch gait is one of the most common compensatory walking patterns found in individuals with neurological disorders, often accompanied by their limited physical capacity. Notable kinematic characteristics of crouch gait are excessive knee flexion during stance and reduced range of motion during swing. Knee exoskeletons have the potential to improve crouch gait by providing precisely controlled torque assistance directly to the knee joint. In this study, we implemented a finite-state machine-based impedance controller for a powered knee exoskeleton to provide assistance during both stance and swing phases for five children and young adults who exhibit chronic crouch gait. The assistance provided a strong orthotic effect, increasing stance phase knee extension by an average of 12 deg. Additionally, the knee range of motion during swing was increased by an average of 15 deg. Changes to spatiotemporal outcomes, such as preferred walking speed and percent stance phase, were inconsistent across subjects and indicative of the underlying intricacies of user response to assistance. This study demonstrates the potential of knee exoskeletons operating in impedance control to mitigate the negative kinematic characteristics of crouch gait during both stance and swing phases of gait.
Real Time, Spatially Resolved Methodology for Flame Dynamics Investigation by Means of Fast Imaging and Image Processing
Authors: Ferrante Antonio
Published: August 2024

This paper presents an innovative tool for the study of flame instability phenomena based on high-speed imaging and image processing. The methodology underlying the system exploits the chemiluminescence radiation produced by the combustion reactions that occur in flames and which are detected by image sensors of high-speed cameras, speeds compatible with the oscillation frequencies of the phenomena we want to investigate. In general, for gas turbine burners the frequency range of interest varies from a few tens of Hz to a few hundred Hz. According to the author, the most innovative aspect of this methodology is that of providing the results of the analyzes in real time and not as a post-process activity. To achieve this result, most measurement analysis calculations are performed not on the CPU but on the GPU, drastically reducing calculation times and allowing the presentation of results in real time. Furthermore, the results presentation part provides a clear visualization of the oscillation modes of light intensity produced by the flame.
Study of the Total Temperature Redistribution in the Complex Swirling Flows
Authors: Karpenko Artem , Kukhtin Yurii
Published: August 2024

This paper reports the results of numerical investigation and analysis of the phenomenon of total temperature separation occurring in energetically isolated flows of compressible fluid. Numerical studies show that this phenomenon is also inherent in the flows of non-viscous ideal fluid in the presence of rotational motion of its particles. Based on the results of the analysis of the equations of motion of an ideal gas in a cylindrical coordinate system, using numerical results, conclusions are drawn about the causes leading to the redistribution of the total temperature in swirling flows of compressible fluid. Examples of flows with rotational motion of fluid particles, in which the studied phenomenon of total temperature redistribution is observed, are shown.
Investigation of Heat Transfer and Flow Characteristics in Rotating Combined Three-Pass Channels
Authors: Che Junxin , You Ruquan , Chen Wenbin , Li Haiwang
Published: August 2024

The combination cooling channels for the three-pass turbine blades are arranged based on the outer contour of the blades, with the flow area changing radially along the blades, and the channels arranged at certain angles to each other. In this study, the copper plate method was employed to investigate the heat transfer characteristics along the channels. The experimental fluid is air, and the maximum uncertainty of the Nusselt number is 7.99%. A detailed exploration of the flow and heat transfer patterns within the variable cross-section combined channels was conducted for Reynolds numbers ranging from 20,000 to 80,000 and rotation numbers ranging from 0 to 0.14. The research results indicate that as the flow area of the channel decreases, the flow accelerates, the disturbance effect of the ribs strengthens, and the heat transfer in the channel sharply increases. Rotation gradually increases the heat transfer difference between the leading side (LS) and trailing side (TS), but as the flow area decreases, the inertial effect strengthens, weakening the impact of rotation on heat transfer. Additionally, the numerical method was employed to study the coupling effects of each passage in the three-passage combined channels. The first passage and turning section enhance the turbulence of the flow but also introduce significant flow losses. Compared to split channels, the turning section leads to an increase in heat transfer in the second passage, but a decrease in heat transfer in the third passage.
Hybrid Electric Aircraft With Unlike Engine Degradation
Authors: Buescher Halle E. , Connolly Joseph W.
Published: August 2024

Control solutions are applied to uneven engine performance degradation on a conceptual twin-engine transport-class aircraft. Such degradation can lead to asymmetric thrust, which requires rudder trim to maintain desired aircraft heading. This will increase drag and fuel consumption. With the introduction of hybrid-electric aircraft powertrains, new solutions to unwanted asymmetric thrust can be derived. Four control strategies are demonstrated on the power and propulsion system of such an aircraft. Compared with existing strategies, the methodology proposed in this paper controls electromechanical actuators coupled to engine shafts and balances the thrust produced by both engines potentially leading to a decrease in fuel burn. The engine represented in this study is NASA’s conceptual dual-shaft Advanced Geared Turbofan 30,000 lbf thrust class engine. The conceptual engine is hybridized with electric machines attached to both shafts. Simulation results are presented with various levels of degradation. The control strategies are compared based on fuel burn, thrust symmetry, and estimated system weight.
Polynomial Chaos Expansion-Based Uncertainty Model for Fast Assessment of Gas Turbine Aero-Engines Thrust Regulation: A Sparse Regression Approach
Authors: Li Shijia , Wei Zhiyuan , Zhang Shuguang , Cen Zhaohui , Tsoutsanis Elias
Published: August 2024

Uncertainties in gas turbine aero-engines are unavoidable among which manufacturing tolerance is a typical manifestation. Uncertainties from manufacturing tolerance directly influence the thrust regulation performance, which may lead to the technical risks of newly produced aero-engines. Moreover, classic sample-based uncertainty quantification approaches are usually computationally intensive. In this paper, to consider the uncertainties in the control design phase in advance, a polynomial chaos expansion-based uncertainty model (PCEUM) using a sparse regression method is proposed to get the accurate probability distribution of thrust regulation performance and other concerned engine variables at a decreased computational burden. In PCEUM, engine variables are initially expressed as linear combinations of several orthogonal polynomials, whose weighting coefficients are solved by a sparse-regression-based method, i.e. orthogonal matching pursuit (OMP). A nominal aero-thermal model for a large turbofan engine, whose maximum errors for key engine parameters are within 2.25% against NPSS data, serves as the basis of PCEUM. Meanwhile, two classic sample-based uncertainty quantification approaches, (i.e. Monte-Carlo simulations (MCS), Latin hypercube sampling (LHS)) and a least angle regression (LARS) based PCE are set as benchmarks. Numerical simulations using publicly available manufacturing tolerance statistics are conducted at take-off states for the tested engine on a desktop computer. Results show that the proposed PCEUM costs only 47.06s at the expense of 200 samples to obtain stable probability distributions for interested engine parameters, e.g. thrust, whose errors of mean and standard deviation compared with MCS at 100,000 samples are within 0.01% and 1%, respectively. While the computational burden of MCS, LHS, and LARS are 854.63s at 9,000 samples, 250.13s at 3,000 samples, and 54.16s at 200 samples at the same precision level, respectively. It means that compared to the latter three methods, PCEUM can save 94.5%, 81.2%, and 13.1% of the simulation time, respectively. Hence, the proposed model is verified regarding both the accuracy and speed for uncertainty assessment, which provides a promising solution for both conventional gas turbine engines and future aero-propulsion systems.
Evaluation of Air Supply Conditioning Architectures for PEM Fuel Cell Systems in Aviation
Authors: Meyer Patrick , Lück Sebastian , Goeing Jan , Friedrichs Jens
Published: August 2024

This paper investigates the cathode air supply system of a medium-range fuel cell-powered aircraft. The main focus is on determining a suitable system architecture. Based on the literature, promising humidification and cooling strategies for cathode gas preconditioning are identified and evaluated. System configurations with membrane and spray humidification as well as intercooling between compressor stages and wet compression are calculated using a thermodynamic cycle calculation model. By analysing the design parameter spaces of the cathode air supply systems, the different configurations are compared in terms of their influence on key system parameters such as specific fuel and parasitic power consumption or heat exchanger size to find the most promising architecture. Further, the operating limits of the systems at different operating pressures and temperatures are determined. The second area of focus is the identification of a suitable system design point. It is discussed that the most critical operating points of the individual components are located at different flight conditions. Therefore, off-design performance is taken into account in order to design the entire system. A model based on the constant mass flow method is introduced to calculate steady state operating points for the system using membrane humidification. It can be seen that the turbo components have their design point at top of climb operating point, while the heat exchanger has to be designed for the maximum waste heat at take-off and the humidifier for the most critical operating point in terms of membrane water content at cruise.
Impact of High Freestream Turbulence on LPT Endwall Flow: Part I – Loss Development and Time-Averaged Flow Field
Authors: Donovan Molly H. , Marks Christopher R. , Fletcher Nathan , Rumpfkeil Markus P.
Published: August 2024

Realistic turbomachinery conditions include high levels of freestream turbulence; however, this aspect of the flow is typically overlooked in both low-pressure turbine (LPT) simulations and experiments. A better understanding of the impact of high freestream turbulence intensity (TI) on the endwall region of LPT blades is imperative. To fully assess the impact of elevated turbulence, three different incoming turbulence levels were examined at three different Reynolds numbers. Three planes of total pressure loss were measured downstream of the cascade mapping loss development. Surface pressure measurements were collected along the blade surface at midspan. Three planes of high-speed Stereoscopic Particle Image Velocimetry (SPIV) were acquired to investigate the impact varying incoming turbulence levels have on the endwall flow structures. Increasing the turbulence to the highest level was found to reduce the overall loss at the exit of the passage. The greatest impact of elevated freestream turbulence was observed at the lowest Reynolds number investigated. The time-averaged velocimetry measurements in the endwall region demonstrated that increasing the freestream turbulence intensity altered the locations of vortices throughout the endwall. Freestream turbulence levels must be increased, better matching real engine conditions, to get a more accurate prediction of pressure losses and flow topology when simulating the flow surrounding LPT blades.
Turbulent Burning Velocity of High Hydrogen Flames
Authors: Rajagopalan Hari Priya , Cole Renee , Wu David , Emerson Benjamin , Lieuwen Timothy
Published: August 2024

The turbulent burning velocity (ST) is one of the most important combustion properties controlling combustor operability limits, directly influencing blowoff, flashback, and combustion instabilities. Hydrogen has particularly significant influences on the turbulent flame speed. This paper presents new H2/CH4 data of high pressure, high hydrogen turbulent burning velocities. The data sets were designed to address fundamental questions as well as provide engineering/design relevant insights. This paper presents new scaling analysis of fuel composition, pressure, and preheat temperature effects on turbulent burning velocity. We also discuss the importance of considering what is being held constant (temperature, flame speed, Reynolds number, etc.) when one is analyzing these sensitivities. Data shows that hydrogen fraction and pressure causes an increase in turbulent flame speed; whether quantified as raw ST,GC, or normalized as ST,GC/SL,0 or ST,GC/SL,max, (where SL,0 and SL,max are the unstretched and stretched laminar flame speed respectively). We also propose that observed increases in ST,GC with pressure are due to increases in Reynolds number, and not a kinetics/stretch sensitivity effect. With increasing preheat temperature, ST,GC increases while its normalized value (ST,GC/SL,0 and ST,GC/SL,max) can either increase or decrease, depending upon fuel composition. We also show how these sensitivities vary, depending on whether these comparisons are made at constant raw turbulence intensity urms, or at constant normalized urms/SL,0 or urms/SL,max.
Unsteady Flow Mechanism of Non-Synchronized Disturbance During Gas Turbine Compressor Start-Up
Authors: Seki Ryosuke , Bonkohara Sho , Okui Hidetaka
Published: August 2024

In this paper, unstable unsteady flow phenomenon that occurs during startup in the compressor of a gas turbine for power generation are investigated in detail. After the rotating stall disappears during startup, a large-scale recirculating flow occurs very rarely at the tip of the 1st rotor over the entire circumferential direction. This stage mismatch causes a large-scale recirculating flow on the casing wall and thus, increases the gas temperature of the tip. This phenomenon ends as the rotational speed increases, and the condition stabilizes at the rated rotational speed, so basically it is not considered to be problematic. However, under certain IGV-VV schedule conditions, there is a rare risk of Non-Synchronized Disturbance (NSD) flow even at the rated speed. Based on these cases, the differences in aerodynamic unsteady flow mechanisms between large-scale recirculating flow and NSD flow were investigated using full annulus unsteady numerical simulations. Although it has been investigated in low-speed rig tests of axial and centrifugal compressors by researchers around the world, there are almost no reported cases in actual gas turbine compressors for power generation, and valuable knowledge about these phenomena was obtained in this paper.

In the case of the large-scale recirculating flow with a deeply closed IGV at 70% part-speed, the large recirculating flow occurs in the range over 75% span from hub (%Ht) to the tip from the leading edge to about 80% axial chord upstream.

On the other hand, if the IGV is half closed than the design opening angle at 100% speed, the reverse flow region occurs locally on the tip side near the leading edge of 95%Ht or higher in the 1st rotor tip. It was found that the rotation of the local reverse flow region in the circumferential direction causes NSD with a peak around 40%–60% of the 1st BPF. The NSD is caused by Kelvin-Helmholtz instability, which occurs when the shear layer between the leading-edge separation and the main flow oscillates.

The mechanism of the unsteady and unstable flow phenomenon which occurred at the start of the gas turbine compressor was clarified by the comparison analysis between the full annulus unsteady numerical simulation and the actual measurement. As a result, it is possible to clarify the direction of improvement measures and contribute to the gas turbine and turbomachinery communities.
Prediction of Steady and Unsteady Flow Quantities Using Multiscale Graph Neural Networks
Authors: Strönisch Sebastian , Sander Maximilian , Meyer Marcus , Knüpfer Andreas
Published: August 2024

Analysis, optimization and uncertainty quantification of the aerodynamic behaviour of turbomachinery components is a fundamental part of the current industrial design process and requires the extensive use of compute-intensive CFD simulations. In this paper we investigate whether graph neural networks can be useful as surrogate models to accelerate the design process, for example in a multi-fidelity framework. Graph neural networks promise to provide good estimates of flow quantities while maintaining the geometric accuracy at a fraction of the computational effort of classical CFD. An application to industrially relevant turbomachinery flows is performed to gain a good understanding of the capabilities and limitations of such methods. We therefore apply a state-of-the-art graph neural network to a turbomachinery setup of industry-relevant mesh size. In particular, a multiscale graph neural network is used to overcome the problems of large information distances when applying message-passing based graph-net blocks to large meshes. The database used to train the network consists of a space-filling DoE of 100 CFD solutions with different geometries. The first use case encompasses the prediction of the flow quantities of the complete fluid domain with 2.5e6 mesh points. The second use case focuses on predicting a single scalar (e.g. pressure or temperature) on surface meshes with up to 30e3 mesh points. In both cases, the networks are employed to predict time-averaged and unsteady flow fields on unstructured meshes of variable point sizes for new geometries not present in the training set. The results demonstrate the proficiency of the approach in predicting time-averaged and unsteady flow quantities on surfaces as well as for full fluid domains for new geometries.
A Dynamic Testing Approach for Particulate Erosion-Corrosion for Gas Turbine Coatings
Authors: Stokes Jamesa L. , Presby Michael J.
Published: August 2024

Particle interactions in gas turbine engines can be multicomponent, complex phenomena leading to the degradation of thermal (TBCs) and environmental barrier coatings (EBCs) meant to protect engine components. Ingestion of particles into the engine can lead to recession of coatings due to particle erosion. Similarly, these same particles can become molten, adhere to coatings and result in thermochemical corrosion of coating materials. Particle erosion testing is often carried out where the particles are injected into a gas stream, accelerated within a nozzle, and impinge on sample. Conversely, most molten particle corrosion testing is often done in static laboratory furnaces, which does not capture the dynamic nature of deposition in application. Nevertheless, these damage mechanisms are often tested separately and no single standard exists to test both erosive and corrosive particle interactions with coating materials under relevant operating conditions for gas turbine engines. Understanding the synergies of particle interactions in engines is crucial in determining operating lifetimes of potential coating materials. Such considerations emphasize the need for realistic approaches in standardizing particle interaction testing in combustion environments. The current study outlines initial efforts at NASA Glenn’s Erosion Burner Rig Facility in improving dynamic erosion/corrosion testing methods by assessing the durability of state-of-the-art (SOA) TBC material 7 wt.% yttria stabilized zirconia (7YSZ) as a function of particle deposition rate, burner temperature, and particle size. Calibration data to determine particle deposition rate will be presented, and mass and optical profilometry measurements were utilized to estimate mass/volume loss versus deposition per increment of particulate used over time. Electron microscopy analyses were then carried out to assess coating damage after testing.
Temperature Margin Calculation During Finite Element Creep Simulations
Authors: Day William , O’Nora Nathan , Gordon Ali P.
Published: August 2024

Creep deformation in turbomachinery applications is a highly non-linear phenomenon. Very small alterations in stress or temperature will substantially change the progression of creep. Common rules-of-thumb would suggest that a change in temperature of +/−10 to 15°C may halve or double the average rupture life respectively. Even in well-controlled laboratory conditions the stochastic nature of creep means that identical tests may differ by a factor of two. Even if an analyst has incorporated a very accurate creep model into an implicit finite element user creep subroutine, they may lack an appreciation of the uncertainty of their solution, or the design changes required to account for uncertainty in either the boundary conditions or the solution itself. Common practice would be to design with maximum strain limit, which may be inadequate given the sudden acceleration of tertiary creep rates. Alternatively, analysts might apply a time factor to their model, necessitating extending the simulation time by factors of two or more. This paper will present a methodology where two estimations of the progression of creep damage are made in parallel to the creep simulation at actual operating temperatures. These two estimations consider the predicted change in stress relaxation at higher or lower temperatures to provide the analyst with an estimate of what change in temperature would result in the model being at the onset of creep at any given node in the model, at any given time in the analysis. This margin calculation is then further expanded to consider the margin required to account for the uncertainty in analytical creep prediction. A time-based scatter factor is then incorporated into the temperature margin calculation to provide a minimum temperature margin including model uncertainty. The analyst is then free to also consider the uncertainty of the temperature prediction and boundary conditions to produce a robust creep prediction in a real-world simulation. The methodology is validated through FEA of example cases and has been applied to the analysis of a creep limited 2 stage industrial gas turbine blade.
Effects of CMAS Application on the Isothermal and Gradient Thermal Cycling Behavior of a Yb2Si2O7 EBC
Authors: Presby Michael J. , Stokes Jamesa L. , Harder Bryan J. , Setlock John A. , Hammel Jeffrey R.
Published: August 2024

Environmental barrier coatings (EBCs) are critical to the continued advancement of gas turbine hot section materials technology. EBCs are required to protect Si-based ceramics such as silicon carbide fiber-reinforced silicon carbide (SiC/SiC) ceramic matrix composites (CMCs) from oxidation and corrosion in the combustion environment. One of the current challenges concerning EBC lifetime is the thermochemical reactions between calcium-magnesium-aluminosilicate (CMAS) deposits and the EBC that leads to changes in both composition and stress state. These changes can severely reduce the integrity of the EBC leading to crack formation, delamination, and spallation. Current techniques for evaluating CMAS in the laboratory rely on the pre-application of CMAS. Two commonly used application methods to deposit CMAS on EBC materials are tape-cast and air spray. In both methods, the CMAS is applied to the EBC surface at ambient temperature, and then subjected to a heat treatment process for binder burnout. The purpose of this study is to compare the tape-cast and air spray methods on the CMAS corrosion of a ytterbium disilicate (Yb2Si2O7) EBC exposed to isothermal, and gradient thermal cycling. The results highlight if any differences exist in the CMAS infiltration kinetics between the two application methods.
Effect of Blade Damage on Low Pressure Ratio Fan Windmill Aerodynamics
Authors: Medina Cassillas Sofía I. , Castillo Pardo Alejandro , Hall Cesare A. , Mohankumar Benjamin
Published: August 2024

Fan windmill occurs when power to a turbofan is cut during flight and the airflow through the engine causes the fan to freewheel, often following fan damage. The fan rotational speed and drag during windmill determine the loads transmitted to the airframe, and these depend on the fan damage sustained. Idealised patterns of axisymmetric and non-axisymmetric damage have been studied using high-resolution measurements in a flow field representative of a low pressure ratio fan in combination with steady RANS simulations to understand the impact on the windmill flow field. Axisymmetric tip damage decreases the windmill rotational speed by 61% when 25% of the blade span is removed due to a shift in the zero-work radius. The reduced blade span creates an intense tip vortex and redistributes the flow, increasing the axial velocity above the damaged tip. For non-axisymmetric damage, there is still work output at the blade tip, such that removing 25% of half the blades with varying damage pitch-to-chord reduces the fan rotational speed by 9–13% compared to undamaged windmill. Phase-averaged hot-wire measurements show that this additional rotor work is due to radial flow redistribution combined with turning of the flow in the passages above the damaged blades.