bluuebunny/crossref_metadata_2025 huggingface dataset:
The origin of great ape gestural forms
Authors: Graham Kirsty E. , Rossano Federico , Moore Richard T.
Published: August 2024

Two views claim to account for the origins of great ape gestural forms. On the Leipzig view, gestural forms are ontogenetically ritualised from action sequences between pairs of individuals. On the St Andrews view, gestures are the product of natural selection for shared gestural forms. The Leipzig view predicts within‐ and between‐group differences between gestural forms that arise as a product of learning in ontogeny. The St Andrews view predicts universal gestural forms comprehensible within and between species that arise because gestural forms were a target of natural selection. We reject both accounts and propose an alternative “recruitment view” of the origins of great ape gestures. According to the recruitment view, great ape gestures recruit features of their existing behavioural repertoire for communicative purposes. Their gestures inherit their communicative functions from visual (and sometimes tactile) presentations of familiar and easily recognisable action schemas and states and parts of the body. To the extent that great ape species possess similar bodies, this predicts mutual comprehensibility within and between species – but without supposing that gestural forms were themselves targets of natural selection. Additionally, we locate great ape gestural communication within a pragmatic framework that is continuous with human communication, and make testable predications for adjudicating between the three alternative views. We propose that the recruitment view best explains existing data, and does so within a mechanistic framework that emphasises continuity between human and non‐human great ape communication.
Government as a Source of Equity Capital for Entrepreneurs: Evidence From Entrepreneurial Exits
Authors: Cumming Douglas , Knill April , Syvrud Kelsey
Published: August 2024

Research Question/Issue

We examine the effect of government equity investment on the dollar value of entrepreneurial exits spanning 50 countries over the years 1990–2015.

Research Findings/Insights

Data on 8532 entrepreneurial exits indicate that, relative to exits in which the investor base is purely nongovernment, private firm exits with government equity investment have higher dollar exit values. Subsample analysis suggests that the exits via initial public offerings (IPOs) drive these results with an average associated increase in IPO proceeds of $192.49 million. The positive impact of government is more pronounced when access to entrepreneurial capital is limited and for limited partnership venture capital structures.

Theoretical/Academic Implications

Research on government equity investment has suggested inefficiencies that lead to the deterioration of corporate value. Conversely, government equity investment can provide a valuable source of capital to some firms when investors, for example, venture capitalists, are unable or unwilling to invest. Our paper sheds light on whether government equity investment can provide value to small private firms, a subset of firms that is typically financially constrained, and how they might enhance exit value.

Practitioner/Policy Implications

Our results suggest that governments enhance value when they provide capital in times/places where capital is scarce and government investors do not actively manage entrepreneurial firms.
IL‐12 minicircle delivery via extracellular vesicles as immunotherapy for bladder cancer
Authors: Wu Zhiyuan , Li Wei , Tan Melissa , How Faith Yuan Xin , Sadhasivan Haripriya , Mahendran Ratha , Wu Qinghui , Chiong Edmund , Le Minh T. N.
Published: August 2024

Interleukin‐12 (IL‐12) holds significant potential in cancer therapy; however, its clinical applicability is hindered by dose‐limiting toxicity. Delivery of the IL‐12 gene directly to tumours for constitutive IL‐12 expression is a possible strategy to enhance its effectiveness while minimizing systemic toxicity. In this study, we investigate the potential of red blood cell‐derived extracellular vesicles (RBCEVs) as a carrier for Il‐12 plasmid delivery. We demonstrate that RBCEVs can be loaded with minicircle plasmid encoding IL‐12 and delivered to MB49 bladder cancer cells for IL‐12 expression. The expression of transgenes from minicircles was significantly higher than from the parental plasmids. RBCEV‐mediated IL‐12 expression stimulated immune responses in mouse splenocytes. Intratumoral delivery of Il‐12 plasmid‐loaded RBCEVs suppressed bladder cancer tumour growth, stimulated immune responses and promoted immune cell infiltration. In conclusion, our study demonstrates the promising potential of RBCEVs as an effective, safe and redosable nucleic acid drug delivery platform for IL‐12.
Irish GDP since independence
Authors: Kenny Seán
Published: August 2024

This paper constructs annual gross domestic product (GDP) estimates for Ireland (1924–47) to join the first complete official aggregates. The new series is deployed to revisit Ireland's economic performance in the post‐independence decades. Ireland's economy grew at just under 1.5 per cent per annum and average living standards improved by 40 per cent. The bulk of this was due to labour productivity improvements. Starting in 1924 captures the civil war recovery and paints a more positive picture of the 1920s, whilst the traditional narrative of a ‛mild’ Great Depression is upheld. The 1930s recovery was aided by strong contributions from services and industry, whilst the economy contracted by almost 7 per cent during the ‛Emergency’. Though supporting O'Rourke's view that Irish growth was not unique against European peers, the new data provide evidence of stronger convergence against UK regions. Industry contributed most to growth during the period, growing at 3.6 per cent per annum. The equivalent rate for services was 1.3 per cent, though it contributed substantially during recovery periods. Agricultural output hardly changed due to its post‐war contraction. This paper joins a growing number of studies that suggest that Ireland was poorer at independence than previously believed.
Assessment of the Hydraulic Profiling Tool for Lower Permeability Characterization
Authors: Liu Gaisheng , Knobbe Steven
Published: August 2024

The Hydraulic Profiling Tool (HPT) has become one of the most widely accepted approaches for obtaining vertical profiles of hydraulic conductivity (K) in environmental site investigations. The current tool, however, is limited to use in moderately permeable settings with a measurable K range of 0.03 to 25 m/d. In this work, we added a low‐flow injection system to standard HPT and modified the field profiling procedure so that it could be used more effectively in lower‐K settings. The modified lower‐K HPT was tested and evaluated against direct‐push slug tests at a field site in the Kansas River floodplain. Results indicated that when the injection rate was reduced, injection pressure decreased, which reduced the potential of injection‐induced formation alteration. A particular challenge of applying HPT in lower‐K zones is the large pressure generated by probe advancement; this can significantly affect the pressure signal measured at the injection screen. Our results showed that the impacts of advancement‐generated pressure could be mitigated by reducing the speed of probe advancement. Compared to K estimates by slug tests, the vertical variability in HPT K was much lower. The reduced variability in HPT K was likely due to formation alteration during probe advancement, as well as pressure interference from injections at previous depths and probe advancement at the bottom. Additional work, such as the use of a smaller‐diameter probe, is needed to further improve the performance of HPT in lower permeability zones.
The impact of headache intensity on speech in participants with migraine and acute post‐traumatic headache
Authors: Smith Dani C. , Zhang Jianwei , Jayasuriya Suren , Berisha Visar , Starling Amaal , Schwedt Todd J. , Chong Catherine D.
Published: August 2024

Background

Slower speaking rates and higher pause rates are found in individuals with migraine or post‐traumatic headache during headache compared to when headache‐free. We aimed to determine whether headache intensity influences the speaking rate and pause rate of participants with migraine or acute post‐traumatic headache (aPTH) following mild traumatic brain injury (mTBI).

Methods

Using a speech elicitation tool, participants with migraine, aPTH, and healthy controls (HC) submitted speech samples over a period of 3 months. Speaking and pause rates were calculated when participants were headache‐free and when they had mild or moderate headache. In this observational study, speaking and pause rates in participants with migraine and aPTH were compared to HC, controlling for age, sex, and days since mTBI (participants with aPTH only).

Results

A total of 2902 longitudinal speech samples from 13 individuals with migraine (mean age = 33.5, SD = 6.6; 12 females/1 male), 43 individuals with aPTH (mean age = 44.4, SD = 13.5; 28 females/15 males), and 56 HC (mean age = 40.8, SD = 13.0; 36 females/20 males) were collected. There was no difference in speaking rate between HC and the combined headache cohort of participants (migraine and aPTH) when they had headache freedom or a mild headache. When participants had moderate intensity headache, their speaking rate was significantly slower compared to that of HC and compared to their speaking rate during mild headache intensity or headache freedom. For the combined headache cohort of participants, pause rates were significantly higher when they had headache freedom or had a headache of mild or moderate intensity relative to HC. Compared to participants' pause rate during headache freedom, their pause rate was significantly higher during mild and moderate headache intensity. Participants with aPTH had significantly slower speaking rates compared to participants with migraine during headache freedom, mild headache intensity, and moderate headache intensity. Participants with aPTH had significantly higher pause rates compared to participants with migraine when experiencing moderate headache intensity.

Discussion

For both aPTH and migraine, more severe headache pain was associated with higher pause rates and slower speaking rates, suggesting that speaking rate and pause rate could serve as objective biomarkers for headache‐related pain. Slower speaking rate in participants with aPTH could reflect additional consequences of TBI‐related effects on motor control and speech production.
Physical Health Checks and Follow‐Up Care in Deprived and Ethnically Diverse People With Severe Mental Illness: Co‐Designed Recommendations for Better Care
Authors: Joury Easter , Beveridge Edward , Littlejohns Judith , Burns Angela , Copsey Gemma , Philips Justin , Begum Shanaz , Shiers David , Chew‐Graham Carolyn , Klass Charlotte , Chin Jackie
Published: August 2024

Background

There is wide variation in premature mortality rates in adults with severe mental illness (SMI) across London, with Tower Hamlets (a highly deprived and ethnically diverse area) scoring the highest.

Objective

To identify examples of best practice and co‐design recommendations for improving physical health checks and follow‐up care amongst people with SMI in Tower Hamlets.

Methods

Data were collected through online questionnaires (using SMI physical health best practice checklists), one‐on‐one interviews (n = 7) and focus groups (n = 3) with general practices, secondary mental health services, commissioners and leads of community services and public health programmes, experts by experience and community, voluntary and social enterprise organisations in Tower Hamlets. Data were analysed using deductive and inductive thematic analysis.

Results

Twenty‐two participants representing 15 general practices (out of 32), secondary mental health services, commissioners and public health leads completed the online questionnaires. Twenty‐one participants took part in interviews and focus groups. Examples of best practice included cleaning and validating the SMI register regularly by general practices, knowing the number of patients who had been offered and/or received physical health checks, having clear pathways to community and specialist care services, using various communication methods and having a key performance indicator (KPI) for tailored smoking cessation services for people with SMI. Recommendations included adopting evidence‐informed frameworks for risk stratification and utilising the wider primary care workforce with specific training to follow up on results, offer interventions and support navigating pathways and taking up follow‐up care. Incentivising schemes were needed to deliver additional physical health check components such as oral health, cancer screening, Covid‐19 vaccination and sexual health checks. Including KPIs in other community services' specifications with reference to SMI people was warranted. Further engagement with experts by experience and staff training were needed.

Conclusion

The present initiative identified best practice examples and co‐designed recommendations for improving physical health checks and follow‐up care in deprived and ethnically diverse people with SMI.

Patient or Public Contribution

This initiative was supported by three experts with experience, and two community organisations, who were involved in data curation and interpretation, development of recommendations and/or dissemination activities including writing this manuscript.
Plasticity in older infants' perception of phonetic contrasts: The role of selective attention in context
Authors: Panneton Robin , Ostroff Wendy L. , Bhullar Naureen , Netto Madeline
Published: August 2024

Developmental plasticity refers to conditions and circumstances that increase phenotypic variability. In infancy, plasticity expands and contracts depending on domains of functioning, developmental history, and timing. In terms of language processing, infants attend to and discriminate both native and non‐native phonetic contrasts, but selectively attune to their native phonemes by the end of the first postnatal year. However, relevant studies have excluded factors regarded as promoters of attention such as infant‐directed (ID) speech, synchronous multimodal presentations, and female speakers. Here we investigated whether English‐learning 11‐month‐olds would discriminate a non‐native phonetic contrast while manipulating these factors. Results showed significant discrimination of the non‐native contrast, regardless of speech register, provided that they were presented by a dynamic female speaker. Interestingly, when a static object or a dynamic male ID speaker replaced the female, no significant discrimination was found. These results show infants to be capable of discriminating non‐native phonetic contrasts in an enhanced context at an age when they have been characterized as not being able to do so. Synchronized, multimodal information from female speakers allowed infants to perceive difficult non‐native phonemes, highlighting the importance of an ecologically valid context for studying speech perception and language learning in early development.
The wettability of pure liquid aluminum on oxide substrates
Authors: Wei Xingwen , Fankhänel Beate , Zhao Wei , Perminov Anton , Storti Enrico , Liu Mengke , Ma Guojun , Fabrichnaya Olga , Charitos Alexandros , Volkova Olena
Published: August 2024

Oxide particles are considered to be one of the reasons for the stability of cellular porous Al foam. Thus, the contact angle (ө) of molten pure aluminum on oxide substrates, including Al2O3, CaO·2Al2O3 (CA2), CaO·6Al2O3 (CA6), mullite (3Al2O3·2SiO2), and SiO2 was measured in a vacuum heating microscope at a temperature of 950°C to determine the value of wettability of molten aluminum on various oxides. Thereafter, the measured contact angles followed the tendency as mullite (155°) > CA6 (152°) > MgAl2O4 (151°) > Al2O3 (149°) > SiO2 (124°) > CA2 (100°). Furthermore, the cross‐sectional area between molten aluminum and substrates was thoroughly analyzed, and the reaction products, such as the Al2O3 layer at the interface, have been detected. Thermo‐Calc, with the combination of available databases, was used to perform thermodynamic simulations and to discuss and predict possible reactions under the current experimental conditions.
Clinical, molecular, physiologic, and therapeutic feature of patients with CHRNA4 and CHRNB2 deficiency: A systematic review
Authors: Jalaiei Abbas , Asadi Mohammad Reza , Daneshmandpour Yousef , Rezazadeh Maryam , Ghafouri‐Fard Soudeh
Published: August 2024

The α4β2 nAChRs are crucial ion channels that control neurotransmitter release and play a role in various physiologic and pathologic processes. CHRNA4 encodes the α4‐nAChRs, while CHRNB2 encodes the β2‐nAChRs. Recent studies have found different variants of α4β2‐nAChRs in individuals with conditions such as AD, ADHD, ALS, PD, and brain abnormalities. We conducted a scoping review following a six‐stage methodology structure and adhering to PRISMA guidelines. We systematically reviewed articles using relevant keywords up to October 2, 2023. In this summary, we cover the clinical symptoms reported, the genes and protein structure of CHRNA4 and CHRNB2, mutations in these genes, inheritance patterns, the functional impact of mutations and polymorphisms in CHRNA4 and CHRNB2, and the epidemiology of these diseases. Recent research indicates that nAChRs may play a significant role in neurodegenerative disorders, possibly impacting neuronal function through yet undiscovered regulatory pathways. Studying how nAChRs interact with disease‐related aggregates in neurodegenerative conditions may lead to new treatment options for these disorders.

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Why do famines still occur in the 21st Century? A review on the causes of extreme food insecurity
Authors: Tezanos‐Vázquez Sergio
Published: August 2024

Why do famines persist in the 21st century, despite significant advances in agricultural productivity? Throughout human history, famines have been – and continue to be – among the harshest manifestations of destitution. They result from the exacerbation of human vulnerabilities caused by the synergistic interaction of multiple anthropogenic and natural determinants. Famines are humanitarian emergencies that sharply increase mortality and/or morbidity among destitute families. This article reviews the academic debate on the causes of famines. The literature is organized into six main “families” of theories: (i) classical economic explanations (Smith's and Malthus’ theses); (ii) food availability decline approach; (iii) entitlement approach; (iv) political perspectives (political regime and political accountability approaches); (v) new variant famine hypothesis; and (vi) systemic explanations. The article identifies the main gaps and limitations in this literature and highlights relevant development policy implications for reducing extreme food insecurity. The conclusion drawn is that the persistence of famines is attributable to ongoing mismanagement of significant triggers of extreme human vulnerability, both at the national and international levels. Extreme poverty, violent conflicts, economic shocks, climate change, governmental negligence, famine crimes, and pandemics contribute to the complexity of famine and require a comprehensive development strategy.
A unilateral increase in the occlusal vertical dimension of growing rats results in mandibular deviation
Authors: Cai Senxin , Liu Jing , Chen Yao , Yang Xinhan , Yan Yuxiang , Zheng Dali , Lu Youguang , Xu Linyu
Published: August 2024

Objective

The effects of unilateral increased occlusal vertical dimension (iOVD) on bilateral craniofacial, mandibular and alveolar development in growing rats were investigated via cone‐beam computed tomography (CBCT). The role of Wnt/β‐catenin signalling in this process was examined.

Materials and Methods

Forty‐eight female Sprague–Dawley rats were randomly allocated into unilateral iOVD and sham groups. At 2, 4 and 8 weeks, the rats were scanned via CBCT to analyse cranial, maxillary, mandibular and dental morphology. Changes in temporomandibular joint (TMJ) cartilage histology and Wnt/β‐catenin signalling were assessed by histochemical and immunohistochemical staining and qRT–PCR.

Results

Dorsal cephalograms revealed that the mandible in the iOVD group tilted approximately 4° to the right. Unilateral iOVD had little effect on cranial and maxillary growth but inhibited mandibular growth (mandibular length and ramal height), especially on the deviated side (DS). Moreover, unilateral iOVD increased the length of the lower incisors and decreased the height of the molars on the DS. Unilateral iOVD induced bilateral osteoarthritis‐like changes in the bilateral TMJ condylar cartilage and activated Wnt/β‐catenin signalling in the condylar cartilage, especially on the contralateral side (CLS).

Conclusion

Occlusion with unilateral iOVD induced mandibular deviation, significantly inhibited mandibular growth and produced compensatory changes in the alveolar bone. In the iOVD group, the mandibular body length and ramal height were greater on the CLS than on the DS. Moreover, the greater β‐catenin protein expression in the TMJ condylar cartilage on the CLS than on the DS may account for the difference in asymmetrical mandibular development.
Harnessing immune priming: A double‐edged defence mechanism in insects
Authors: Subhagan Seena R. , Pathrose Berin , Chellappan Mani
Published: August 2024

Insects are known to dominate adverse ecological conditions due to their diverse adaptations and resilient biological traits, with their immune systems playing a crucial role in this dominance. Traditionally, insects were thought to lack adaptive immune responses due to their inability to produce antibodies and transfer immunity across generations. However, recent research using insects as model organisms has challenged this notion, revealing that prior exposure to sublethal doses of pathogens or pathogen‐derived materials can protect against subsequent lethal exposures—a phenomenon known as ‘immune priming’. Evidence of bacterial, fungal and viral immune priming across different insect species highlights various types of priming, including trans‐stadial (across life stages) and trans‐generational (across generations) priming. Despite differing views on immune priming, its potential applications in agriculture are considerable, especially in biological control, the utilization of beneficial insects and sustainable pest management. This review explores the intricate dynamics of immune priming in insects, comparing it to vertebrate immunity and investigates its mechanisms, potential agricultural applications and future prospects.
Nutrition for all? Input subsidies and equitable diets
Authors: Ng'ombe John N. , Prah Stephen , Kiwanuka‐Lubinda Rebecca N. , Nkonde Chewe
Published: August 2024

While agricultural input subsidies can improve productivity and nutrition, a key unanswered question is whether such government initiatives influence equitable nutrition access across genders. We study gender disparities in dietary diversity among 7783 smallholder farms in Zambia, evaluating the potential of subsidies to mitigate gaps. Using Oaxaca‐Blinder decomposition methods, results reveal female‐headed households (FHHs) have significantly lower dietary diversity than male‐headed ones, with gaps ranging from 6% to 12% along the distribution. Male‐headed households (MHHs) also show 9% higher input subsidy participation, influenced by education and agricultural extension access among others. Crucially, increased FHHs' participation in input subsidies could potentially close the gendered dietary diversity gap, even surpassing MHHs by 17.8%, underscoring the promise of targeted efforts to improve gender equity. However, achieving socioeconomic parity with MHHs further amplifies positive impacts. Given these findings, facilitating FHHSs' access to input subsidies can promote more equitable nutrition outcomes between genders. Broader participation could be enabled by strengthening agricultural extension and education to equip farmers, especially marginalized female‐headed and remote households, to leverage subsidized inputs. Overall, this study demonstrates that prioritizing female‐headed households' inclusion in input subsidy programs, alongside integrated support, holds strong potential to narrow gendered disparities in dietary diversity among smallholder farms in Zambia. It provides key insights to inform the design of nutrition‐sensitive, gender‐aware agricultural policies.
Differential effect of lead and cadmium on mitochondrial function and NLRP3 inflammasome activation in human trophoblast
Authors: Dai Yifeng , Xu Xijin , Huo Xia , Schuitemaker Joost H. N. , Faas Marijke M.
Published: August 2024

Heavy metals disrupt mitochondrial function and activate the NOD‐like receptor pyrin‐containing 3 (NLRP3) inflammasome. We investigated the effect of lead (Pb)/cadmium (Cd) on mitochondrial function and NLRP3 inflammasome activation in human trophoblast under normoxic, hypoxic and pro‐inflammatory conditions. JEG‐3, BeWo and HTR‐8/SVneo cells were exposed to Pb or Cd for 24 h in the absence or presence of hypoxia or pro‐inflammatory lipopolysaccharide (LPS) or poly(I:C). Then, we evaluated cell viability, apoptosis, mitochondrial DNA copy number (mtDNAcn), mitochondrial membrane potential (ΔΨ), NLRP3 inflammasome proteins and interleukin (IL)‐1β secretion. Although our data showed that Pb, Cd, hypoxia, poly(I:C) and LPS decreased mtDNAcn in the three cell lines, the effects of these treatments on other biomarkers were different in the different cell lines. We found that hypoxia decreased ΔΨ and promoted apoptosis in JEG‐3 cells, increased ΔΨ and prevented apoptosis in BeWo cells, and did not change ΔΨ and apoptosis in HTR‐8/SVneo cells. Moreover, Pb under hypoxic conditions reduced ΔΨ and promoted apoptosis of BeWo cells. Exposure of BeWo and HTR‐8/SVneo cells to hypoxia, Pb or Cd alone upregulated the expression of NLRP3 and pro‐caspase 1 but did not activate the NLRP3 inflammasome since cleaved‐caspase 1 and IL‐1β were not increased. To conclude, Pb and Cd affected trophoblast mitochondrial function and NLRP3 proteins in trophoblast cell lines, but in a cell line‐specific way.

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Key points

The objective of this work was an understanding of the effect of lead (Pb) and cadmium (Cd) on mitochondrial function and NLRP3 inflammasome activation in human trophoblast cell lines under normoxic, hypoxic and pro‐inflammatory conditions.

Apoptosis of JEG‐3 cells was increased by hypoxia, while in BeWo cells, apoptosis was decreased by hypoxia, and in HTR‐8/SVneo, apoptosis was not affected by hypoxic treatment.

Exposure to either Pb or Cd decreased mtDNAcn in three human placental trophoblast cell lines. However, Pb under hypoxia induced a decrease of ΔΨ and promoted apoptosis of BeWo cells, but Cd did not induce a reduction in ΔΨ in the three trophoblast cell lines under any conditions.

Exposure to hypoxia, Pb or Cd increased NLRP3 and pro‐caspase 1 in BeWo and HTR‐8/SVneo cells.

Our findings highlight that Pb and Cd affected trophoblast mitochondrial function and NLRP3 proteins in trophoblast cell lines but in a cell line‐specific way.
Fatigue Failure of Steam Turbine Discs – A Centenary Tribute to Wilfred Campbell
Authors: Gowreesan Vamadevan , Grebinnyk Kirill , Pemmasani Mahesh
Published: August 2024

The year 2024 marks one hundred years since Wilfred Campbell published his landmark work on vibrational analysis of rotating disc following a series of disc failures in steam turbines. Despite the absence of advanced engineering analytical tools, Campbell came up with an elegant method to visually demonstrate and capture the mode shapes in rotating discs. The first part of this paper reviews Campbell’s life and analytical and experimental work in this area.

Regardless of the current advanced engineering capabilities to predict nodal shapes in turbine discs, turbine discs still experience failures related to vibration. The second part of the paper discusses a recent case study where a turbine disc failure occurred as a result of vibration. The discussion includes metallurgical root cause failure analysis and engineering analysis to predict the vibrational characteristics. Metallurgical failure analysis confirmed that the primary mode of failure was fatigue and did not have any issues with the disc material or its mechanical properties. Finite element modeling and analysis were used for the engineering analysis to predict the natural frequencies of the bladed-disc. The engineering analysis showed the evidence of potential resonance, and the failure was related to nodal vibration issues.
Aerodynamic Design of Refrigeration Compressor for Optimal Range and Efficiency
Authors: Dey Sudip , Muley Nitin
Published: August 2024

There is an increasing trend in using oil-free centrifugal compressors in refrigeration chillers and heat pumps for superior efficiency, lower maintenance, and reduced lifecycle costs. Centrifugal compressors for chiller application are subjected to wider operating range when compared to those used in many other applications. While numerous aerodynamic and numerical design tools are either commercially available or developed by specific manufacturers and/or research institutions, designers face significant challenges in choosing appropriate design attributes and dimensions of flow path components, especially when additionally constrained by stagewise performance, bearings, rotordynamics, and overall layout.

This paper demonstrates how commercially available design and analyses tools are used to perform aerodynamic design and optimization of aerodynamic flow-path of a refrigeration centrifugal compressor to enhance operating range and aerothermal efficiency while maintaining pressure ratio or chiller capacity within expected operating regime. Relevant details of one-dimensional (1D) and two-dimensional (2D) design are shown along with some details of three-dimensional (3D) numerical (CFD) analysis. This paper also illustrates how selection of various components and overall layout influences design and aerodynamic optimization of the impellers. Numerical analysis is also performed to optimize axial thrust for the pair of opposed configured impellers mounted on the same shaft. Moreover, the same numerical model provides superior insight about overall performance impact for the presence of shaft seals or secondary flow paths. Finally, test findings at the in-house test facility are shared to compare overall performance of the original and the modified compressor.
Decomposition of Compressible and Thermal Contributions to the Exergy-Balance-Based Analysis of the NASA Rotor 37
Authors: Berhouni Ilyès , Petropoulos Ilias , Bailly Didier
Published: August 2024

This paper presents the application of a new exergy balance decomposition allowing to explicitly isolate the compressible and thermal contributions to overall efficiency for the NASA rotor 37 performance analysis. Firstly, the theoretical aspect of this new decomposition is discussed in detail, including the expressions, interpretations and figures of merit associated to the different components. Secondly, one operating regime at 98% of the choke mass flow rate of the rotor 37 is investigated. This will particularly emphasize the trends obtained for the thermally- and mechanically-recoverable components of the overall exergy outflow (respectively impacted by entropy generation and pressure/velocity differences with respect to the system’s thermodynamic dead state). Finally, the analysis of the exergy-based characteristic of the compressor is refined with respect to the one based on the original mechanical/thermocompressible decomposition. In particular, it is found that the impact of the thermally-recoverable exergy outflow on the prediction of the compressor efficiency is non-negligible, as it corresponds to roughly 0.4% of the computed compressor rotor stage overall efficiency. As this component is only convertible into mechanical work by means of a heat engine (not available in current-generation aircraft engines), isolating the thermally-recoverable component is thus essential in exergy-based performance analyses.
An Innovative and Ambitious Student Design Project: To Build a Small-Scale Brayton Cycle Engine on a Short Timeline With a Limited Budget
Authors: Keesee Charles L. , DeLong Jakob , Fig Matthew , Hibl Gaylord , Ebsch Zachariah , Homola Dustin , Mimong Isaac , Thompson Bonnie , Young Chandler
Published: August 2024

The Brayton Cycle is one of the primary gas power cycles taught as part of any thermodynamics course. While students learn its operation in various configurations on paper, they are not always afforded the opportunity to work with an actual gas turbine engine up close. This project allowed students to use knowledge learned in the classroom and apply it to a real design problem. Design projects early in an engineering program are less common since the focus is generally on the fundamental equations; however, solving complex engineering problems and applying these solutions to designs are among the required ABET program outcomes. Therefore, enhancing the students’ skills in these areas early and often is a motivation for early design projects. To accomplish this, students enrolled in Fluid Mechanics Laboratory, a junior-level course, were tasked with designing and building a small-scale Brayton Cycle on a limited budget in a very short timeframe. In addition to preparing students for senior design this project aimed to be truly multifaceted as it combined skills and knowledge learned in several previous courses such as: Thermodynamics, Fluid Mechanics, Instrumentation, Machine Design, and Circuits. Uniquely, this design assignment did not stop with the paper plans but required the students to build a testable prototype. This allowed them to learn firsthand how manufacturing limitations and supply chain delays can impact the final design. While it was desired that the turbine would generate enough power to ultimately drive the compressor it was understood that such a goal may be infeasible. Therefore, the focus was more on the design process as opposed to designing and fabricating a working gas turbine engine.
Gas Turbine Drives for Pipeline-Compressors: Assessing the Influence of H2-Blends on Performance, Load Dynamics, and Emissions of a Gas Turbine With DLE Technology in a Real-World Field-Study
Authors: Rudolph Charlotte , Sciancalepore Maurizio , Vesper Deborah , Schiffer Tobias , Bainier Francis , Lauzat Thorsten
Published: August 2024

The integration of hydrogen into the natural gas infrastructure poses new challenges for existing technologies, such as gas turbines or compressors. Investigating the behavior of those plants, especially gas turbines as mechanical drives, under future fuel requirements in a real environment is thus essential for the development of the future energy system.

The work presented here examines the compatibility of a 15-MW gas turbine equipped with dry-low-emission (DLE) technology with hydrogen-enriched natural gas blends, addressing performance, emissions, and dynamics. Further to the modification of the gas turbine and the development of a blending unit, project-related aspects are also described and discussed.

The gas turbine displayed good performance, with minimal impacts on power output, thermal efficiency, and fuel consumption in the investigated H2 range. Carbon-based emissions were negligible, while NOx emissions increased with rising H2 fraction, but remained below acceptable limits. In addition, the gas turbine control system successfully activated the DLE mode with any H2 blend. This study confirmed the gas turbine’s suitability for use in the natural gas grid with H2 fractions of up to 25%, demonstrating the potential of this gas turbine for a sustainable energy supply and the importance of thorough testing and monitoring during the transition from fossil fuels to hydrogen.
Utilisation of Evaporated Ethanol in Natural Gas Fired Lean-Premix Combustors of Power Generation Gas Turbines
Authors: Abbott David , van Eil Tijn , Klein Sikke , Goy Catherine
Published: August 2024

With the transition to low-carbon power generation there will be a continuing need for dispatchable power. This could be provided by gas turbines fired with low-carbon fuels.

It has been shown that micro-gas turbines with lean premix natural gas combustors can successfully fire a wide range of evaporated liquid fuels without modification. It is possible that larger power generation gas turbines will also be able to utilise evaporated liquid fuels without significant modification. Ethanol and methanol were considered by the authors, but methanol was eliminated during pre-screening.

This preliminary assessment considers the potential for power generation gas turbines to burn evaporated ethanol in lean premix burners. A Siemens SGT5-2000E gas turbine as operated in Uniper’s Killingholme plant is used as an example.

Impacts on key combustion performance parameters (emissions, combustion dynamics, flashback and blow-off) have been considered. These parameters are affected by both chemical properties of the fuels and the effect of their physical properties on burner aerodynamics, fuel placement and mixing quality. The evaluation included a combination of chemical kinetic modelling and isothermal CFD.

This analysis has concluded that the concept would be viable and warrants further investigation.
Numerical Analysis of Heat Transfer Inhomogeneity of Supercritical Pressure Carbon Dioxide in Horizontal Minichannels
Authors: Li Ni , Fang Zheng , Pu Hang , Mu Lin , Shang Yan , Dong Ming
Published: August 2024

To prevent local overshoot of heat exchanger wall temperature in the Brayton cycle system, this study numerically investigated the heat transfer inhomogeneity of turbulent mixed convection of SCO2 inside flow passages with different cross-sections of circular, semicircular, and rectangular cross-sections. The operating parameters corresponded to the low-pressure side of a heat exchanger (p = 8 MPa, Tin = 303 K, q/G = 41.67–250 J·kg−1). It was found that the variation of density with temperature led to the secondary flow in the cross-sections. The heat transfer inhomogeneity emerged with the development of secondary flow, and increased during the peaks of isobaric specific heat capacity (cp) and thermal conductivity (λ) moved from the buffer layer to the logarithmic-law layer. When the peaks of cp and λ converged in the logarithmic-law layer, the heat transfer inhomogeneity decreased. In a circular tube, the heat transfer inhomogeneity can be ignored when q/G = 41.67 (heat transfer enhancement), but when q/G ⩾ 125 (heat transfer deterioration) the heat transfer inhomogeneity cannot be ignored. Under the same q/G condition, the intensity of secondary flow was inversely proportional to G, so the heat transfer inhomogeneity decreased with increasing G. Affected by channel geometry, the variation of maximum wall temperature difference (ΔTmax) coincided with the wall temperature inhomogeneity (δT) for a circular channel, but not for semicircular and rectangular channels. ΔTmax was the largest for a semicircular channel while δT was the largest for a rectangular channel under identical operating conditions.
Development and Evaluation of Additively Manufactured Sensors for Combustor Surface Temperature, Heat Flux and Strain Measurements
Authors: Chandh Aravind , Adhikari Subodh , Wu David , Lieuwen Tim , Emerson Benjamin
Published: August 2024

System components with embedded sensors help obtain real-time system performance feedback and in situ monitoring during operation. This paper describes the development and assessment of embedded sensors fabricated employing a Direct Wire (DW) deposition process, which enables their integration directly onto the components being tested. Three separate combustor panels were additively manufactured using the Direct Metal Laser Sintering (DMLS) technique with 1) thermocouples, 2) heat flux gages, and 3) strain gages embedded on the cold side of combustor panels. These surface contact sensors are a few millimeters wide and are within 50 μm thick and thus, have minimal effect on the reacting flow field of a combustor. They were first characterized in a controlled environment (oven and strain beam tests) and then tested in a single nozzle liquid spray reacting combustor simulating realistic aircraft conditions operated at elevated pressures of up to 4 bar and inlet temperatures starting at 410 K. These sensors survived the harsh operating environment involving high-temperature settings for an extended period and cyclic thermal loading and exhibited repeatable and reliable readings. This paper serves as a demonstration of these additively embedded sensors and provides data from the combustion test rig to show repeatability and transient response characteristics. This development is useful for R&D purposes of current-gen energy, automotive, and aerospace systems and in the development of more efficient and smarter next-gen combustion systems.
GPU-Accelerated Actuator-Disk Large-Eddy Simulation for Wind Farm Flows
Authors: Dabas Jérôme , Staffelbach Gabriel , Odier Nicolas , Duchaine Florent , Gicquel Laurent
Published: August 2024

The power production of a wind farm depends on complex interactions between the atmospheric boundary layer (ABL), the wind turbines and their wakes. These interactions can be captured with accuracy and at a reasonable cost using an Actuator-Disk Large-Eddy Simulation (AD-LES) approach [1] where the most energetic scales of the ABL are resolved while wind turbines are modelled by volume forces. The present study shows that this approach can be used with GPU-acceleration to simulate an entire wind farm at a reasonable turnaround time.

To do so, the AD model has been implemented for GPU architectures in the CERFACS’ LES solver AVBP [2], the approach being then validated on the Horns Rev wind farm configuration in neutral atmospheric boundary layer [3]. Good agreement is found between field measurements and numerical predictions. In addition, the LES flow field is used to assess wake models and investigate various wake superposition laws to better understand their effect on the power prediction.
Loss Breakdown in Axial Turbines: A New Method for Vortex Loss and Wake Detection From 3D RANS Simulations
Authors: Raina Greta , Bousquet Yannick , Luquet David , Lippinois Eric , Binder Nicolas
Published: August 2024

To enhance turbine efficiency, it is essential to mitigate the loss generated by irreversible phenomena taking place in turbine flows, including boundary layers, shock waves, vortices and trailing edge wakes. A fast and accurate detection of losses is therefore crucial from the earliest stages of turbine design, in which low-fidelity models based on oversimplified correlations are employed. Achieving this objective requires a deep comprehension of the physics behind each loss-generating mechanism, a goal attainable through the examination of the 3D flow. While existing criteria allow the identification of various phenomena, accurately quantifying losses generated by vortices remains a challenge: these losses frequently extend beyond the vortical structure. The aim of this paper is to provide a straightforward and effective approach to localize and assess vortex-related losses. This method is grounded in Zlatinov’s decomposition of the entropy generation rate equation into a stream-wise and a secondary flow component. A criterion based on the vortex kinematics is used to evaluate the strength of the vortex, thereby enabling the determination of its spatial influence and its contribution to the overall losses. To validate the method, a post-processing code is developed which allows to perform loss breakdown. This tool makes use of existing identification criteria and some new techniques introduced within this work, especially for wake detection. 3D RANS simulations are carried out on several configurations, ranging from simple curved ducts to more realistic nozzle guide vanes (NGV), to gradually test and validate the computational tool. Results confirm that the highest rates of entropy generation occur outside of the vortical structure, and show good ability to identify both the vortex shape and its area of influence in terms of losses. A drastic improvement in the prediction of vortex losses is especially observed in the case of turbine blades with tip or hub leakage vortices.
Micro Gas Turbine Fed With Ammonia As Fuel: Performance Analysis and NOx Emissions Reduction
Authors: Fatehi Mohsen , Campaldini Graziano , Renzi Massimiliano
Published: August 2024

The increasing global demand for energy and the need to reduce polluting emissions necessitate the use of alternative fuels, especially in the hard-to-abate sectors, that are more critical from an environmental standpoint. Ammonia is considered as a promising carrier of green hydrogen and as a renewable carbon-free fuel, therefore, it is anticipated to play a fundamental role in the decarbonization of the energy supply chain. In this study, a simulation algorithm has been used to evaluate the performance of a 3.2 kWe Micro Gas Turbine (MGT) fed by ammonia. The algorithm comprises a set of equations describing the behavior of the MGT’s components, and the consumption of the auxiliary devices. To examine the combustion kinetics and evaluate the MGT emissions with ammonia feed, a further algorithm utilizing Cantera library has been developed. This model is a one-dimensional tool that allows to assess the mixing flows in the combustion chamber, the temperature trends, and the formation of the combustion products. Results indicate that, if a suitable fuel injection and an air supply strategies are used, the electric power output obtained using Ammonia (NH3) turns out to be comparable to that obtained with Methane (CH4), while the electric efficiency is marginally lower (5.16%). In this work, due to the high amount of NOx emission when using ammonia, the Rich-Lean non-premixed combustion strategy is investigated in a three-stage combustion chamber. By adopting this strategy, the amount of NOx concentration has been reduced to 744 ppm (15% O2 dilution), about 92% less than original strategy.