bluuebunny/crossref_metadata_2025 huggingface dataset:
AI‐powered visual diagnosis of vulvar lichen sclerosus: A pilot study
Authors: Gottfrois Philippe , Zhu Jie , Steiger Alexandra , Amruthalingam Ludovic , Kind Andre B. , Heinzelmann Viola , Mang Claudia , Navarini Alexander A. , Mueller Simon M.
Published: August 2024

Background

Vulvar lichen sclerosus (VLS) is a chronic inflammatory skin condition associated with significant impairment of quality of life and potential risk of malignant transformation. However, diagnosis of VLS is often delayed due to its variable clinical presentation and shame‐related late consultation. Machine learning (ML)‐trained image recognition software could potentially facilitate early diagnosis of VLS.

Objective

To develop a ML‐trained image‐based model for the detection of VLS.

Methods

Images of both VLS and non‐VLS anogenital skin were collected, anonymized, and selected. In the VLS images, 10 typical skin signs (whitening, hyperkeratosis, purpura/ecchymosis, erosion/ulcers/excoriation, erythema, labial fusion, narrowing of the introitus, labia minora resorption, posterior commissure (fourchette) band formation and atrophic shiny skin) were manually labelled. A deep convolutional neural network was built using the training set as input data and then evaluated using the test set, where the developed algorithm was run three times and the results were then averaged.

Results

A total of 684 VLS images and 403 non‐VLS images (70% healthy vulva and 30% with other vulvar diseases) were included after the selection process. A deep learning algorithm was developed by training on 775 images (469 VLS and 306 non‐VLS) and testing on 312 images (215 VLS and 97 non‐VLS). This algorithm performed accurately in discriminating between VLS and non‐VLS cases (including healthy individuals and non‐VLS dermatoses), with mean values of 0.94, 0.99 and 0.95 for recall, precision and accuracy, respectively.

Conclusions

This pilot project demonstrated that our image‐based deep learning model can effectively discriminate between VLS and non‐VLS skin, representing a promising tool for future use by clinicians and possibly patients. However, prospective studies are needed to validate the applicability and accuracy of our model in a real‐world setting.
Agent‐based intra‐regional relocation model considering spatial local amenity for urban planning‐based flood risk management: Assessing the impact of urban development on flood exposure
Authors: Tanaka Tomohiro , Koga Asuka , Yokomatsu Muneta
Published: August 2024

Integrated flood risk management based on urban policies remains challenging compared with infrastructure due to the unclear risk‐reduction effects over time. To consider heterogeneity in social responses to urban planning measures, a previous study developed an agent‐based household relocation model under flood risk (AHR‐FLOOD) by combining flood‐inundation and agent‐based relocation models. However, accurate modelling of relocation incentives remains challenging. This study aimed to improve AHR‐FLOOD by introducing spatial amenities based on transportation convenience and reflecting their impact on the decision‐making processes of agents to analyze the development of different flood risk areas. AHR‐FLOOD considering access to public transportation reproduced the spatial characteristics of the actual population and housing prices. The development of low‐risk areas reduced flood exposure and resulting flood damage. However, this effect was less clear for low‐income individuals, but the development of low‐amenity areas had the potential to induce low‐income population to move to safe areas. Chain migration was observed as a long‐term effect of the spatial amenity policy. This study presents insights into the effect of transportation policies on flood safety for long‐term spatial distance management in an agent‐based approach with the rigorous modelling and validation of local amenity impact on household relocation choices.
Experimental Replacement of Zircon by Melt‐Mediated Coupled Dissolution‐Precipitation Causes Dispersion in U–Pb Ages
Authors: Asimus Jeremy L. , Daczko Nathan R. , Gazi Jean‐Antoine , Ezad Isra S. , Belousov Ivan , Rodemann Thomas , Halpin Jacqueline A. , Piazolo Sandra
Published: August 2024

Zircon geochronology provides critical information on the rates and durations of geological processes and enables researchers to explore deep time. However, some zircon datasets show a continuum of concordant ages (‘smear’) without well‐defined age populations. These age smears are typically interpreted to represent variable loss of radiogenic Pb or protracted geological events lasting tens of millions of years. Coupled dissolution‐precipitation replacement of zircon has been suggested as one process that may produce these complex age datasets. Here, we react fragments of the well characterised Mud Tank zircon standard with natural intermediate and mafic melts (0.9 GPa, 1100–1180°C) to test if short‐term exposure to a melt can modify the geochronological patterns of zircon. Our observations show that within a short duration (18 h to 3.5 days), most Mud Tank zircon fragments display microstructural and/or chemical evidence for modification by dissolution at fragment boundaries along with partial replacement by coupled dissolution‐precipitation processes. The replaced zircon domains have U–Pb ages that smear over one hundred million years, between 764–647 Ma, illustrating variable mobility and redistribution of the U and Pb isotopes. Our experiments demonstrate that zircon modified by coupled dissolution‐precipitation replacement may not faithfully record the age or duration of geological events and that investigation of zircon microstructure in high‐resolution backscattered electron, cathodoluminescence imaging and/or Raman mapping is needed to better understand complex zircon geochronological datasets.
Gastric neuroendocrine tumors: 20‐Year experience in a reference center
Authors: Ravizza Davide , Giunta Mariangela , Sala Isabella , Bagnardi Vincenzo , Tamayo Darina , de Roberto Giuseppe , Trovato Cristina , Bravi Ivana , Soru Pietro , Maregatti Margherita , Pisa Eleonora , Bertani Emilio , Bonomo Guido , Spada Francesca , Nicola Fazio
Published: August 2024

Few studies have been published on the long‐term outcomes of patients with gastric neuroendocrine tumors (gNETs). We analyzed their management over a two‐decade period, focusing on endoscopic and clinical outcomes. Clinical, laboratory, endoscopic, surgical, and histopathological data from Types 1 and 3 gNETs histologically diagnosed between March 2000 and December 2021 at the European Institute of Oncology (IEO, Milan) were retrospectively collected. Sixty‐nine patients were included (60 Type 1, 9 Type 3): 53 (77%) were treated endoscopically, 6 (9%) surgically, and 10 (14%) did not receive any treatment. Overall, 293 lesions were removed endoscopically: 74% by forceps, 20% by endoscopic mucosal resection (EMR), and 5% by endoscopic submucosal dissection (ESD). No differences were observed between EMR and ESD in terms of complete resection rate (p value = .50) and complications rate (p value = .084). The median follow‐up period was 5.8 years (range: 0.3–20.5), during which no gNET‐related deaths were observed. Metachronous gNETs developed in 60% of patients with Type 1 gNET. Six patients with lymph node metastases (LNM) were younger (p value = .006) and had larger lesions (p value <.001) than patients without LNM. Most Type 1 gNETs were successfully excised using forceps, with EMR and ESD being equally effective. The presence of incomplete resection was not associated with a worse prognosis, which remains excellent in this highly recurrent disease. Younger age and a size ≥10 mm were associated with an increased risk of LNM.

Clinical Trial Registration

Project code UID 2854.
Cyclosporine A improves the binding of mouse embryos to fibronectin
Authors: Shengnan Tian , Mei Zheng , Jiaxing Wang , Dan Li , YanLin Ma , Huang Yuanhua
Published: August 2024

Aim

The binding of integrin αvβ3 with endometrial fibronectin (FN) promotes the migration of preimplantation embryos in mice. We have previously shown that cyclosporine A (CsA) improves the adhesion and invasion of mouse preimplantation embryos. In this study, we evaluated the roles of calcium ions and downstream signaling factors in the binding of integrin αvβ3 to FN.

Methods

Female Institute of Cancer Research (ICR) mice were superovulated and mated, and two‐cell embryos were harvested from the oviducts and cultured to the blastocyst stage The adhesion and stretching growth of hatched embryos in laminin‐coated dishes were evaluated, and integrinβ3 expression was determined using qPCR. Blastocytes were cultured with 0 or 1  cyclosporine A (CsA) and the attachment of embryonic integrin αvβ3 to FN120 was observed using a fluorescent bead. To further determine the mechanism, the cells were also incubated with calcium ions and protein kinase C and calmodulin antagonists. The binding of integrin αvβ3 to FN120 was examined via confocal laser scanning microscopy.

Results

The adhesion and stretching growth of peri‐implantation embryos were greater and integrinβ3 expression was higher in the 1 μM CsA group than in the 0 μM CsA group (p < 0.05). When incubated with calcium ions and protein kinase C and calmodulin antagonists, the ability of peri‐implantation embryos to bind to FN decreased; CsA treatment promoted this binding.

Conclusion

This study revealed that CsA up − regulates integrinβ3 expression in peri − implantation embryos and promotes binding to FN via calcium ions, and protein kinase C, and calmodulin. These findings provide evidence supporting the beneficial effect of CsA on the peri − implantation embryo adhesion.
GSK3s promote the phyB‐ELF3‐HMR complex formation to regulate plant thermomorphogenesis
Authors: Yang Ruizhen , Dong Huixue , Xie Xianzhi , Zhang Yunwei , Sun Jiaqiang
Published: August 2024

Although elevated ambient temperature causes many effects on plant growth and development, the mechanisms of plant high‐ambient temperature sensing remain unknown.

In this study, we show that GLYCOGEN SYNTHASE KINASE 3s (GSK3s) negatively regulate high‐ambient temperature response and oligomerize upon high‐temperature treatment. We demonstrate that GSK3 kinase BIN2 specifically interacts with the high‐temperature sensor phytochrome B (phyB) but not the high‐temperature sensor EARLY FLOWER 3 (ELF3) to phosphorylate and promote phyB photobody formation.

Furthermore, we show that phosphorylation of phyB by GSK3s promotes its interaction with ELF3. Subsequently, we find that ELF3 recruits the phyB photobody facilitator HEMERA (HMR) to promote its association with phyB.

Taken together, our data reveal a mechanism that GSK3s promote the phyB‐ELF3‐HMR complex formation in regulating plant thermomorphogenesis.
Exploring the effects of red light night break on the defence mechanisms of tomato against fungal pathogen Botrytis cinerea
Authors: Kukri András , Czékus Zalán , Gallé Ágnes , Nagy Gábor , Zsindely Nóra , Bodai László , Galgóczy László , Hamow Kamirán Áron , Szalai Gabriella , Ördög Attila , Poór Péter
Published: August 2024

Plant infections caused by fungi lead to significant crop losses worldwide every year. This study aims to better understand the plant defence mechanisms regulated by red light, in particular, the effects of red light at night when most phytopathogens are highly infectious. Our results showed that superoxide production significantly increased immediately after red light exposure and, together with hydrogen peroxide levels, was highest at dawn after 30 min of nocturnal red‐light treatment. In parallel, red‐light‐induced expression and increased the activities of several antioxidant enzymes. The nocturnal red light did not affect salicylic acid but increased jasmonic acid levels immediately after illumination, whereas abscisic acid levels increased 3 h after nocturnal red‐light exposure at dawn. Based on the RNAseq data, red light immediately increased the transcription of several chloroplastic chlorophyll a‐b binding protein and circadian rhythm‐related genes, such as Constans 1, CONSTANS interacting protein 1 and zinc finger protein CONSTANS‐LIKE 10. In addition, the levels of several transcription factors were also increased after red light exposure, such as the DOF zinc finger protein and a MYB transcription factor involved in the regulation of circadian rhythms and defence responses in tomato. In addition to identifying these key transcription factors in tomato, the application of red light at night for one week not only reactivated key antioxidant enzymes at the gene and enzyme activity level at dawn but also contributed to a more efficient and successful defence against Botrytis cinerea infection.
Weak long‐range diffusion
Authors: Garvey R. S. , Fowler A. C.
Published: August 2024

We study the spreading solutions of the nonlinear diffusion equation  when the far‐field diffusivity is small. The method of strained coordinates is used to construct a uniform asymptotic correction to the similarity solution of the unperturbed problem. The equation provides a possible analogue to similar models of fluid jets and plumes.
Colorful vector balancing
Authors: Ambrus Gergely , Bozzai Rainie
Published: August 2024

We extend classical estimates for the vector balancing constant of equipped with the Euclidean and the maximum norms proved in the 1980s by showing that for and , given vector families with , one may select vectors with
for , and
for . These bounds are sharp and asymptotically sharp, respectively, for . The proofs combine linear algebraic and probabilistic methods with a Gaussian random walk argument.
Loss of the alpha subunit distal furin cleavage site blunts ENaC activation following Na+ restriction
Authors: Nickerson Andrew J. , Sheng Shaohu , Cox Natalie A. , Szekely Kennedy G. , Marciszyn Allison L. , Lam Tracey , Chen Jingxin , Gingras Sebastien , Kashlan Ossama B. , Kirabo Annet , Hughey Rebecca P. , Ray Evan C. , Kleyman Thomas R.
Published: August 2024

Epithelial Na+ channels (ENaCs) are activated by proteolysis of the α and γ subunits at specific sites flanking embedded inhibitory tracts. To examine the role of α subunit proteolysis in channel activation in vivo, we generated mice lacking the distal furin cleavage site in the α subunit (αF2M mice). On a normal Na+ control diet, no differences in ENaC protein abundance in kidney or distal colon were noted between wild‐type (WT) and αF2M mice. Patch‐clamp analyses revealed similar levels of ENaC activity in kidney tubules, while no physiologically relevant differences in blood chemistry or aldosterone levels were detected. Male αF2M mice did exhibit diminished ENaC activity in the distal colon, as measured by amiloride‐sensitive short‐circuit current (ISC). Following dietary Na+ restriction, WT and αF2M mice had similar natriuretic and colonic ISC responses to amiloride. However, single‐channel activity was significantly lower in kidney tubules from Na+‐restricted αF2M mice compared with WT littermates. ENaC α and γ subunit expression in kidney and distal colon were also enhanced in Na+‐restricted αF2M vs. WT mice, in association with higher aldosterone levels. These data provide evidence that disrupting α subunit proteolysis impairs ENaC activity in vivo, requiring compensation in response to Na+ restriction.

image

Key points

The epithelial Na+ channel (ENaC) is activated by proteolytic cleavage in vitro, but key questions regarding the role of ENaC proteolysis in terms of whole‐animal physiology remain to be addressed.

We studied the in vivo importance of this mechanism by generating a mouse model with a genetic disruption to a key cleavage site in the ENaC's α subunit (αF2M mice).

We found that αF2M mice did not exhibit a physiologically relevant phenotype under normal dietary conditions, but have impaired ENaC activation (channel open probability) in the kidney during salt restriction.

ENaC function at the organ level was preserved in salt‐restricted αF2M mice, but this was associated with higher aldosterone levels and increased expression of ENaC subunits, suggesting compensation was required to maintain homeostasis.

These results provide the first evidence that ENaC α subunit proteolysis is a key regulator of channel activity in vivo.
Optimum Geometrical Models for Prediction of Phase Transition of Single Crystal Nickel Based Superalloys via the Discrete Cosine Transform and the Maximum Entropy Method
Authors: Hiraguchi Hideo
Published: August 2024

A new prediction method using the combination of the two-dimensional Discrete Cosine Transform and the Maximum Entropy method has recently appeared to estimate the dynamic changes of metallographic structures of the single crystal Nickel-based superalloy for gas turbine blades during the high temperature creep deformation. In the analysis of this method, simple geometrical models are used to estimate the dynamic changes of the phase transition. However, it has not been understood how the difference between the multiple simple geometrical models affect the result of the prediction of dynamic changes of structures yet. Therefore, three different simple geometrical models meshed into 21 × 21 (441 pixels) are prepared as the target model and demonstrated via the above mentioned new method, in the situation that the starting simple geometrical model is the same one. The first model is a symmetrical model whose symmetrical plane is parallel to the i axis and perpendicular to the j axis at the 10th scale line, the second one is a model which the first model is moved in the j axis direction by one pixel and the third one is a model which the first model is moved in the j axis direction by two pixels. As a result, the dynamic changes obtained from the symmetrical model and the one pixel deviation model are the most realistic of the three models.
Effects of Radially Variable Sweep Vanes on Rotor-Stator Interaction Noise
Authors: Shen Zihan , Wang Xiaoyu , Zhang Guangyu , Sun Xiaofeng
Published: August 2024

This paper presents a three-dimensional semi-analytic cascade model for the prediction of rotor-stator interaction noise, which includes the effects of radially variable sweep angle and chord length to better account for the latest trends in the fanstage stator design of turbofan aero-engines. The theoretical modelling and solution method are first introduced, with special attention paid to the singularity problem brought by the non-uniformity of the stator vanes in the radial direction. The tonal rotor-stator interaction noise for stators with a radially varying sweep angle or a radially varying chord length are then calculated and analyzed. It is discovered that the phase variation in unsteady pressure loading near the stator leading edge greatly affects the resulting tonal interaction noise, while the sweep of a stator trailing edge shows less influence on the rotor-stator interaction. The duct mode characteristic of the cut-on modes is proved to be an important factor for the design of a swept stator. In addition, the soft vane design can further reduce the tonal interaction noise on a swept stator cascade.
Development of Hydrogen and Micromix Combustor for Small and Medium Size Gas Turbine of Kawasaki
Authors: Aoki Shigeki , Uto Takahiro , Takahashi Nobuaki , Okada Kunio , Kroniger Daniel , Kamiya Hiromu , Yamaguchi Masato , Ishimura Yuki , Wirsum Manfred , Funke Harald H.-W. , Kusterer Karsten
Published: August 2024

Kawasaki (KHI) has made various improvements and commercialized hydrogen gas turbines for existing diffusion combustors (0–100 vol.% H2, wet combustion) and lean pre-mixed DLE combustors (0–30 vol.% H2). However, it is challenging for conventional combustion technology to achieve dry low NOx emissions for 100 vol.% hydrogen. Kawasaki’s unique approach is the development of a new dry combustion technology for high hydrogen content fuel: the micromix (MMX) combustion. Kawasaki established this combustion technology to achieve low NOx for 100 vol.% hydrogen combustion. Micromix is based on a large number of miniaturized non-premixed-type flames, making this concept inherently safe toward flashback. Recently, Kawasaki has commercialized a gas turbine with a micromix combustor as the world’s first dry gas turbine capable for 100 vol.% hydrogen. This paper shows the latest improvements of the micromix combustor before the commercialization with focus on NOx reduction achieved by decreasing the fuel injection hole diameter, and the extension of the operational flexibility by applying a supplemental burner system. During demonstration tests with a 1.8 MWel gas turbine, it could be proven that this novel combustion concept meets Japan’s fundamental NOx regulations (84 ppm referred to 15 vol.% residual O2) for pure hydrogen and furthermore can be operated with natural gas/hydrogen blends in the range up to 50 vol.% H2 over the entire load range.
Nondestructive Creep Damage Evaluation for Ni-Base Superalloys of Controlled Solidification by Laue Method and Effect of Sample Thickness
Authors: Iwasaki Shinya , Kobayashi Daisuke , Tateishi Toshikatsu , Yokoyama Ryoichi , Omote Kazuhiko
Published: August 2024

Ni-base superalloys exhibit high deformation resistance characteristics, even at elevated temperatures. However, it is difficult to determine the state of damage from the appearance and observation of the microstructure. Although it is possible to quantitatively estimate plastic strain and creep strain using electron backscatter diffraction (EBSD), it is a destructive method. On the other hand, X-ray diffraction using the Laue method has the potential to non-destructively evaluate material damage.

In this study, we investigated the effect of sample thickness on the evaluation using the Laue method. We also compared the creep damage evaluation results of solidification-controlled Nibase superalloys using the EBSD and Laue methods and examined the possibility of non-destructive evaluation of creep damage using the Laue method.

The specimens used to investigate the effect of sample thickness were single-crystal blocks of Ni-base superalloys. Samples were prepared with five different thicknesses. Next, we compared the full width at half maximum (FWHM) of Ni-base superalloys in single-crystal blocks of different thicknesses. The measured FWHM were almost constant, independent of the thickness. This may be because the combination of subgrains and X-ray microbeams results in a sparser distribution of detected diffraction spots and a decrease in the number of high-intensity diffraction lines.

The specimens for comparison of the EBSD and transmission Laue methods were Ni-base directionally solidified (DS) superalloys, and damaged pieces were fabricated at several stages of creep testing up to rupture and evaluated using each method. As a result of comparing the EBSD and transmission Laue methods, the technique is capable of detecting microstructural changes associated with the later stages of creep deformation.

These results indicate the transmission Laue method is a promising non-destructive evaluation method because the FWHM does not depend on the sample thickness and can perform evaluations like the EBSD method.
Numerical Simulations of Ice Particle Transport at Representative Turbofan Compressor Conditions
Authors: Parker Liam , McGilvray Matthew , Gillespie David R. H. , Jones Geoffrey
Published: August 2024

Engine icing threatens compressor operation and service life. Ice crystal ingestion at cruise and descent phases of flight result in smaller, partial melted crystals entering the engine core. Here, crystals can stick to stationary surfaces driven by the presence of a water film, and evaporative and melting heat exchange with the mixed phase crystals. Modelling of the ice crystal cloud conditions is needed to understand threat areas within the core and operating envelope and to provide a reliable basis for ice accretion modelling at solid surfaces. A particle transport model in three-dimensions combining tracking, heat transfer, phase change along with a turbophoresis model is presented for non-spherical mixed phase ice crystals. These present a challenge to model effectively considering the complex and anisotropic geometries of ice crystals. Further, crystals can fragment, melt and agglomerate along the gas path. This affects heat transfer, phase change and ice porosity which will implicate the deposition location and composition. The model is validated against previous altitude icing wind tunnel experiments at LP/IP compressor operating conditions. Measured conditions for ice crystal mass flux provide experimental comparison against particle advection and phase change. Particle advection is modelled using an Euler-Lagrangian approach with two-way mass-energy coupling. Particle turbulent dispersion is modelled using a discrete random walk (DRW) model which is appropriate for flows where particles are primarily inertially-moderated. The model is seen to predict particle cloud mass distribution to within 15% of the experimentally measured total water content (TWC). Particle sizes between 2 μm and 131 μm and are modelled as spheroids. The variation in melt response is investigated relative to particle size and aspect ratio. High aspect ratio particles (AR > 10) result in 5% to 20% phase change augmentation depending on the particle angle of attack. Two way coupling is shown to increase the melt ratio by up to 10% and reduce the total water content by up to 25% compared to one-way coupling. The model provides a framework for compressor stage ice particle transport and deposition in ice crystal icing conditions.
On the Combustion of Terpenes Biofuels and Pollutants Characterization Through High-Resolution Mass Spectrometry
Authors: Dagaut Philippe , Dbouk Zahraa , Benoit Roland
Published: August 2024

Terpenes are a class of hydrocarbon compounds naturally found in plants. They already have a variety of uses, such as flavor and fragrance additives. Also, they can be blended with conventional or synthetic liquid fuels. Understanding the kinetics of terpenes combustion is important for the development of cleaner combustion, as well as for evaluating associated air pollution and environmental impacts. Therefore, the oxidation of terpenes has been performed under well-controlled conditions. The cool flame oxidation of limonene, α-pinene, and β-pinene, terpenes commonly emitted by vegetation, was performed in a jet-stirred reactor under fuel-lean conditions, at 1 bar. Samples of the reacting mixtures were collected, dissolved in acetonitrile, and analyzed by high-resolution mass spectrometry. Direct flow injection and chromatographic separation by ultra-high-performance liquid chromatography were used. Heated electrospray ionization and atmospheric pressure chemical ionization were employed to characterize the products of oxidation. H/D exchange using D2O was performed for probing the presence of hydroxyl and hydroperoxyl groups in the products. The Brady reaction was used to assess the presence of carbonyl functional groups in the products. A large set of oxidation products, including highly oxidized organic products with 5 and more oxygen atoms, was observed. Besides, FTIR analyzes of gas products were performed. Aromatic and/or polyunsaturated products were detected. Graphic tools including Van Krevelen plots, aromaticity index, and maximum carbonyl ratio, and Venn plots were used to analyze the results. Reaction pathways are proposed to rationalize the results.
Characterization of Windshield Effectiveness in Improving Air Cooled Condenser Performance Under High Winds and its Impact on Steam Turbine Power Output
Authors: Bianchini Cosimo , Da Soghe Riccardo , Giannini Lorenzo , Gardner Andrew , Wilde Jamie
Published: August 2024

Large mechanical draft Air-Cooled Condensers (ACC) are prone to a decay of efficiency and to fan blade load fluctuations that largely increase in the case of high-speed winds and strongly depend on wind directions. A common and relatively simple strategy used to mitigate such wind losses is the installation of partially porous screens made of specialized fabric that acts as wind breakers.

A previous numerical study defined a CFD methodology able to quantify the ACC cooling capacity deficit due to wind and identified a ground installed vertical windshield in the shape of a cross as the most effective means to recover such losses under the most critical wind conditions.

In this paper, the same CFD model was used to characterize the windshield performance under different wind conditions covering a large range of wind speeds and directions. Furthermore, the analysis is expanded coupling the ACC heat transfer predicted by CFD with a thermodynamic model of the steam cycle that permitted to compute the thermal equilibrium between the steam and air side.

Feeding the thermodynamic model with appropriate weather forecasts, it was possible to compute the expected extra annual production thanks to the windshield installation. Providing installation costs and energy selling prices, the developed tool permits a reasonable estimate of the payback period for the investment in windshields which proved to vary largely depending on the energy selling price but was always less than a year for the selected locations.
Data-Driven Inverse Design Method for Turbomachinery
Authors: So Kwok Kai , Salamanca Luis , Ozdemir Firat , Perez-Cruz Fernando
Published: August 2024

A data-driven inverse design method based on neural networks is proposed for turbomachinery. In the devised methodology, design parameters are provided as input to the neural network, and performance attributes, e.g. efficiency, as output. Once trained, the network is used for inverse design, i.e. target performance values are prescribed to generate various design parameter sets. Through empirical experiments, it is observed that the true efficiency of the network-generated radial turbine and thrust bearing designs are in good agreement with the prescribed target efficiencies. Furthermore, the proposed model can be used to accurately generate designs beyond the range of the training data set, showing strong generalization properties. The proposed approach offers the additional benefit of easy implementation, being fully data-driven and not requiring any modifications to the data generation process. As long as data is available, the method can readily be extended to account for multi-component and multi-physics aspects. After a model is trained using a set of design parameters, the proposed method can also be used to generate a subset of design parameters for prescribed target attributes with ease. The data-driven inverse design method represents a novel design approach in the age of big data, and is highly relevant and applicable for turbomachinery designs where an abundance of design data, pairing design parameters and target attributes is available. Notably, through generating a large variety of accurate designs with improved performance, the proposed method effectively indicates trust regions in the design space where further design explorations could be carried out, showing a significant impact on optimisation strategies.
Experimental and Numerical Investigation of Hydrogen Combustion in a Dual-Swirl Burner for Aero-Engine Applications
Authors: Gövert Simon , Berger Johannes , Lipkowicz Jonathan Timo , Soworka Thomas , Hassa Christoph , Behrendt Thomas , Janus Bertram
Published: August 2024

Green hydrogen produced by electrolysis offers a high potential for reducing CO2 emissions and thus represents a promising approach for the decarbonization of aviation. However, propulsion systems based on direct hydrogen combustion require modified fuel injectors and combustion chambers to account for the particular combustion characteristics of hydrogen. Engineering those modifications requires the acquisition of experimental and numerical tools especially suited for this task and in the end validating them in a suitable environment. In this context, hydrogen combustion and its numerical simulation is presented with a dual-swirl burner in an optically accessible atmospheric combustor as an intermediate step. The fuel injector was originally designed to simulate kerosene combustion with natural gas at atmospheric conditions by producing a gas film with mixing properties similar to a kerosene film. In this study, this natural gas fuel injector is adopted for combustion of pure hydrogen. To ensure safe operation and to reduce the risk of flashback, fuel and air are injected non-premixed. Good flame stability and mixing, which leads to potentially low NOx values, is achieved by introducing a swirling motion into the flows. Therefore, the air is fed through a co-rotating dual-swirler configuration. In the circumferential shear layer in-between, hydrogen is injected axially with a co-rotating velocity component. In this study, the combustor is operated under atmospheric pressure at a globally lean equivalence ratio. While hydrogen and cooling air are injected at ambient temperature, the burner air is preheated to 376.2 K. Cooling air is lead along the inner walls of the heat shield for convective cooling and enters the combustion chamber at the outer walls where it forms a cooling film for the side walls. Further cooling air is introduced via downstream located dilution ports to reduce the temperature at the combustor exit. Measurements of OH* radical chemiluminescence as well as infrared radiation as a marker of the hot water vapor distribution have been carried out to identify the flame location and shape. The configuration is further analyzed by means of reacting Large-Eddy-Simulations using the Flamelet-Generated-Manifolds combustion model in combination with the Dynamic Thickened Flame model. The comparison of the simulation results with the experimental reference data shows that the flame lift of height and global flame spread are correctly predicted by the simulation for both operating conditions. However, the combustion model does not precisely capture the flame stabilization mechanism, leading to a radial offset of the flame front.
Experimental Investigation on the Dynamic Response of a Turbocharger Centrifugal Compressor in Surge Transitions
Authors: Silvestri Paolo , Marelli Silvia , Usai Vittorio
Published: August 2024

Centrifugal compressors play a critical role in various industrial applications, and understanding their operational behavior, especially during surge conditions, is essential for enhancing efficiency and reliability. Surge is a phenomenon that leads to significant pressure and mass flow rate fluctuations. Compressors can be damaged from surge instability, which results in vibrations and thermal stress. This study investigates surge transitions in centrifugal compressors by employing a comprehensive approach that integrates dynamic mass flow rate and pressure measurements using anemometric fiber film probes and high frequency piezoresistive pressure transducers together with dynamic structural response data.

To gain insight into the transition from the stable to the unstable region of the compressor, an extensive experimental analysis on a centrifugal compressor was conducted at the University of Genoa test bench for components of propulsion system. The activity involves measurements used to characterize and identify the behavior of the compressor in correspondence of surge inception conditions.

Measurements were conducted for different corrected rotational speed level stable and unstable operating points on the compressor characteristic curves including incipient and deep surge conditions were acquired, considering also different outlet circuit lines.

Pressure transducers and anemometric film probes were employed to gather data on the compressor’s fluid dynamics. Frequency and time-frequency data analysis techniques have been employed to examine the inflow pressure and the anemometric signal. The purpose is to identify their characteristics and define the compressor operation as stable or unstable. Synchronous averages, applied in the time domain, have proven to be effective for detecting incipient surge conditions jointly with variance computation. Additionally, statistical techniques, such as variance and spectral kurtosis, have been utilized for the detection in signals with strong additive noise of transient and non-deterministic contents may rise approaching instable conditions.

A method for system identifying in deep surge is introduced, particularly a correlation between the compressor circuit geometries and the operating condition of the turbocharger is proposed. This approach enhances the diagnostic capability of the monitoring system by providing a better knowledge of surge occurrence. The paper is aimed to provide information for the development of advanced control strategies and predictive maintenance protocols to mitigate surge-related issues and improve the overall performance and reliability of centrifugal compressors.
Data-Driven Generative Model Aimed to Create Synthetic Data for the Long-Term Forecast of Gas Turbine Operation
Authors: Losi Enzo , Manservigi Lucrezia , Spina Pier Ruggero , Venturini Mauro
Published: August 2024

The prediction of gas turbine (GT) future health state plays a strategic role in the current energy sector. However, in the case of limited historical data, e.g., a new installation, training an accurate prognostic model may be challenging.

To this aim, this paper develops a Generative Adversarial Network (GAN) model aimed to generate synthetic data that can be used for data augmentation. The GAN model includes two neural networks, i.e., a generator and a discriminator. The generator aims to generate synthetic data that mimic the pattern of real data. The discriminator is a binary classification network. During the training process, the generator is optimized to fool the discriminator in distinguishing between real and synthetic data.

The real data employed in this paper were taken from the literature and gathered from three GTs. Data refer to two quantities, i.e., corrected power output and compressor efficiency, which are tracked during several years.

Three different analyses are presented to validate the reliability of the synthetic dataset. First, a visual comparison of real and synthetic data is performed. Then, two metrics are employed to quantitively evaluate the similarity between real and synthetic data distributions. Finally, a digital twin (DT) model is trained by only using synthetic data and then it is employed for the prediction of real data.

The results prove the high reliability of the synthetic data, which can be thus exploited to train a DT model suitable for prognostic purposes. In fact, the prediction error of the DT model on the real data is lower than 2.5% even in the case of long-term prediction.
Numerical Investigation of the Heat Transfer and Discharge Coefficient of the Narrow Double Wall Cooling
Authors: Xu Qingzong , Du Qiang , Wang Pei , Xu Guangyao , Liu Haoyang , Li Hongye
Published: August 2024

A numerical investigation was conducted to explore the heat transfer and discharge characteristics of a narrow double wall cooling configuration. The narrow double wall cooling configuration comprises a row of impingement holes and a row of film holes. Two impingement distances, Z/D = 1 and Z/D = 2, were studied, along with six impingement Reynolds numbers ranging from 5000 to 30000. In addition, the layout of the impingement hole and the film hole was also investigated. The study employed the RANS method with the SST k-ω turbulence model. In addition to investigating heat transfer on the impingement target wall, the heat transfer on the side wall and the impingement wall was also examined to assess heat flux distribution within the system. The results indicate that impingement distance rarely affects heat transfer on the target wall in the context of narrow double wall cooling. When the impingement distance is increased from Z/D = 1 to Z/D = 2, there is a noticeable rise in heat transfer on the side wall and the impingement wall, leading to a higher total heat flux within the impingement channel. Results indicate that reversing the positions of the impingement and film holes has negligible effect on the target wall heat transfer. Furthermore, the overall discharge coefficient, considering both the impingement hole and the film hole, remains comparable for the three schemes studied. The reverse impingement film cooling decreases the discharge coefficient of the film hole due to the large flow separation at the hole inlet.
Impact of the Blade Fillet Radius on the Aerodynamic Performance of an Unshrouded Centrifugal Compressor
Authors: Hoang Duc Huy Marco , Châtel Arnaud , Verstraete Tom
Published: August 2024

Fillets are often neglected in the flow analysis of centrifugal compressors due to the assumption of having little influence on the flow field and the difficulties related to the grid generation. Existing studies have shown an impact on efficiency, pressure ratio and choke margin by including fillets in the flow simulation. The goal of the present work is to investigate the impact of the fillet radius on the aerodynamic performance in an unshrouded centrifugal compressor. A parametric study on the blade hub fillet radius is conducted using the “RadiVer” test geometry and steady state CFD analysis. By using common methods for grid generation of turbomachinery blade passages, which are stacking the surface grids for each blade section, 3D features, such as fillets, cannot be meshed properly. Therefore, a new topology for 3D multi-block structured grid generation of radial impeller blades including hub fillets is proposed. Transfinite interpolation is used to create the initial grid and elliptic smoothing is applied afterwards for removing grid folding and improving grid quality.

From the results of the flow simulations an improvement of the compressor performance with larger fillet radius is observed. Modifying the fillet radius mainly influences the flow downstream of the blade trailing edge. Even though the impeller efficiency decreases as the fillet size gets larger, due to the increased tip leakage flow, the diffuser performance improves, leading to an overall increase of the compressor efficiency. The improvement of the diffuser performance is attributed to the lower static pressure at the trailing edge as the fillet radius increases. The lower static pressure allows the flow to get sucked out from the backwards facing step and to distribute over the whole span of the diffuser. On the one hand, this leads to increased mixing losses. On the other hand, the entrapment of the flow at the backwards facing step can be avoided in that way, which overall leads to a reduced total pressure loss in the diffuser.
Enhanced Adiabatic Film Cooling Effectiveness by Varying Compound Angle
Authors: Pyo Yeongmin , Broumand Mohsen , Son Juchan , Richer Patrick , Jodoin Bertrand , Hong Zekai
Published: August 2024

Effusion cooling is the state-of-the-art cooling technology for gas turbines. However, the compound angle of effusion cooling holes is commonly set as a fixed value in prior studies. In particular, the compound angle is mostly set to zero in practice by assuming that highly directional miniature effusion cooling jets are aligned with the main flow. A recent study from our group has examined the directional effects of effusion cooling on adiabatic film cooling effectiveness (AFE) subjecting to a swirling main flow. It was found that a large compound angle initially facilitates a quick build-up of cooling film and the optimal compound angle reduced to smaller values downstream where the cooling film is further developed. The current study exploits the recent findings in the directional effects of effusion cooling by proposing novel effusion cooling designs with varying compound angles of cooling holes which are optimized for improving AFE along the main flow direction. In the present study, AFE was experimentally determined using Pressure Sensitive Paint (PSP) through invoking the heat/mass transfer analogy. A new effusion cooling design was evaluated by setting the compound angles of effusion cooling holes to three discrete values of 90, 60, and 30 degrees at three successive regions along the direction of the main flow. 2D AFE maps resulting from the proposed design were compared with those of conventional effusion cooling designs with fixed compound angles under identical conditions. It was found that the new effusion cooling design featuring varying compound angles produces a more uniform cooling film coverage and a small enhancement to AFE comparing to the conventional effusion cooling designs.
Few Common Observations From a Vibration Test Data
Authors: Kumar Avinash , Iyappan Praveen , Kumbham Krishna Mohan
Published: August 2024

Typical vibration test data, especially from transient vibration tests, contains several observations with reference to test data measurement quality and physics of response. In this paper, few common observations are highlighted. These observations are obtained from both shock type test and steady state vibration test. First observation — In case of shock type loading, accelerometer data is usually found to have multiple local drifts in the signal. It is understood that presence of these multiple drifts doesn’t necessarily mean that the data is corrupted, but data can still be very reliable if drifts are removed. Second observation — In a system with significant rubs during dynamic test, it is commonly observed that vibration response contains frequencies of multiple orders of fundamental excitation frequency. Vibration at multiple orders is localized to the rubbing zone and dies away as we move far from the rubbing zone. Third observation — During shock testing, accelerometers contain large acceleration at higher frequencies, while strain gauge data doesn’t usually show significant strain at higher frequencies. Higher acceleration at higher frequencies leads to smaller displacement which then leads to lower loading into the system. Fourth observation — In case of base excitation tests, in which input signal is multi-tonal, high frequency tones gets attenuated through the compliant mounting and doesn’t show as an output on mounted device. These observations are described in detail in this paper.
Effect of the Upstream Shroud Purge Flow on the Cooling Performances of Turbine Blade Tip
Authors: Xue Zhenzhen , Li Haiwang , Tao Zhi , Zhou Zhiyu , Meng Long , Xie Gang
Published: August 2024

Researches on the turbine blade tip cooling mainly focus on the arrangement of the film holes in the blade tip and the shroud. In fact, the purge flow located upstream of the turbine blade leading edge also influences the cooling of the turbine blade tip region. In present study, the effects of purge flow on the cooling performance and flow field around the blade tip were investigated by numerical simulation using 3-D steady RANS approach with the k-ω turbulence model. The first-stage high-pressure turbine blade of GE-E3 was employed in present work. Three parameters of the purge flow were investigated, which were the inlet angle of the purge flow (30°, 60° and 90°), the relative position between the leading edge of the blade and the purge flow (10 %, 25 % and 40 % of the vane-blade distance), and the mass flow rate of the coolant (1 %, 1.5 % and 2 % of the main flow rate). The results indicate that the presence of the shroud purge flow has a significant influence on the film cooling of blade tip. As the inlet angle increases, higher vertical velocity reduces the lift-off of cooling jet, leading to worse tip cooling performance. However as the distance increases, the cooling performance improves. As the coolant flow rate increases, the cooling performance gets better.