bluuebunny/crossref_metadata_2025 huggingface dataset:
Age‐related declines in ejaculate quality and sperm kinematics vary among strains of Japanese Quail (Coturnix japonica)
Authors: Farooq Umar , Malecki Irek A. , Mahmood Misbah , Martin Graeme B.
Published: November 2019

For successful breeding programs, it is important to quantify the useful period of a male's reproductive life and it is often done simply by measurement of semen quality. This information is lacking for Japanese quail so we tested whether there is a decline in ejaculate quality and sperm kinematics with age, and whether the decline varies among strains. Nine males (n = 9) from each of 5 strains (A, B, C, D and E) were subjected to 4 semen collections (n = 16 per male) at 8, 16, 26 and 36 weeks of age. Ejaculate volume, sperm concentration and total sperm per ejaculate were measured, and sperm kinematics were analysed using a Sperm Class Analyser (SCA®). There was a significant effect of age for ejaculate volume, total sperm per ejaculate and per cent medium sperm. The effect of the interaction between age and strain was significant for percent progressive motile sperm, percent rapid sperm, velocity curvilinear, velocity straight line, velocity average path, linearity, straightness and beat cross frequency. Ejaculate volume peaked at Week 26 in all strains, while peak values for sperm concentration and total sperm per ejaculate were observed at Week 16 for most strains. There were declines in percent motile sperm, progressive motile sperm and rapid sperm, and in velocity curvilinear velocity, velocity straight line and velocity average path, by Week 16 for most strains. Linearity declined by Week 26 in some strains, and all strains showed a significant decline in beat cross frequency by that age. In conclusion, the ability of CASA to detect age‐related changes in sperm kinematics makes it a valuable tool for identifying the best males and thus improving quail flock fertility. It is essential that breeders understand that age affects both sperm production and sperm kinematics, and that the changes vary with strain.
Characterization of Historical Methane Occurrence Frequencies from U.S. Underground Natural Gas Storage Facilities with Implications for Risk Management, Operations, and Regulatory Policy
Authors: Schultz Richard A. , Hubbard Douglas W. , Evans David J. , Savage Sam L.
Published: November 2019

Defining a baseline for the frequency of occurrences at underground natural gas storage facilities is critical to maintaining safe operation and to the development of appropriate risk management plans and regulatory approaches. Currently used frequency‐estimation methods are reviewed and broadened in this article to include critical factors of cause, severity, and uncertainty that contribute to risk. A Bayesian probabilistic analysis characterizes the aleatoric historical occurrence frequencies given imperfect sampling. Frequencies for the three main storage facility types in the United States (depleted oil‐and‐gas field storage, aquifer storage, solution‐mined salt cavern storage) are generally on the order of 3 to 9 × 10–2occurrences, of all causes (surface, well integrity, subsurface integrity) and severities (nuisance, serious, catastrophic), per facility‐year. Loss of well integrity is associated with many, but not all, occurrences either within the subsurface or from there up to the surface. The probability of one serious or catastrophic leakage occurrence to the ground surface within the next 10 years, assuming constant number of facilities, is approximately 0.1–0.3% for any facility type. Storage operators and industry regulators can use occurrence frequencies, their associated probabilities and uncertainties, and forecasts of severity magnitudes to better prioritize resources, establish a baseline against which progress toward achieving a reduction target could be measured, and develop more effective mitigation/monitoring/reduction programs in a risk management plan.
The CCL20 and CCR6 axis in psoriasis
Authors: Furue Kazuhisa , Ito Takamichi , Tsuji Gaku , Nakahara Takeshi , Furue Masutaka
Published: November 2019

Psoriasis is a TNF‐α/IL‐23/IL‐17A–mediated inflammatory skin disease that causes a significant socioeconomic burden in afflicted patients. IL‐17A–producing immune cells, including Th17 cells, are crucial effector cells in the development of psoriasis. IL‐17A stimulates epidermal keratinocytes to produce CCL20, which eventually recruits CCR6 + Th17 cells into the lesional skin. Thus, the CCL20/CCR6 axis works as a driving force that prepares an IL‐17A–rich cutaneous milieu. In this review, we summarize the current research topics on the CCL20/CCR6 axis and the therapeutic intervention of this axis for psoriasis.
Rural Sociology Revival: Engagements, Enactments and Affectments for Uncertain Times
Authors: Carolan Michael
Published: November 2019

This article, originally a Keynote Address at the XXVIII European Society for Rural Sociology Congress (Trondheim, Norway, 25–28 June 2019), reflects on my positionality as a citizen‐academic at a time when democracies around the world are threatened by runaway incivility, anxiety and hate. Such reflexivity ought to be encouraged in the field and ultimately leveraged as we practice engaged scholarship that also affords empathy and justice. Much of my recent scholarship represents, in part, a response to personal frustrations and anxieties in the face of tensions around authoritarian populism and rural‐urban asymmetries. The research reviewed touches on such subjects as political ontologies, the politics surrounding public and private concerns, the future as a Durkheimian social fact, rural‐urban linkages and social justice. The data presented attempts, collectively, to make the point the while the twenty‐first century is said to belong to cities, the field of rural sociology has never been more salient. The article speaks of how and why a recommitment to our sociological roots, which involves further embracing our sociological imaginations, may help others better grasp the field’s value, while helping the academy better grapple with issues of social justice.
Collective citizenship: From citizenship and mental health to citizenship and solidarity
Authors: Quinn Neil , Bromage Billy , Rowe Michael
Published: November 2019

Although the concept of citizenship is a widely used theoretical framework within political philosophy, its use in the field of mental health remains underexplored. Within this context, citizenship emphasises the social inclusion and participation of people who are marginalized and offers a more social and relational view of services and support for people with mental health problems than has been common in mental health systems of care. At the same time, however, the citizenship approach has operated in the context of systems of care in the United States that favour highly individualized conceptions of, and approaches to, care, and these systems of care operate in the social and political context of highly individualized concepts of the citizen. In this article building on the work of other citizenship scholars, we argue that a collective form of citizenship, grounded in the 5Rs framework, holds the individual and collective in creative tension. Furthermore, the paper applies this model to the domain of mental health, where people are treated in individualistic ways and experience marginalisation, making the collective dimension imperative and promoting participation, empowerment and the contribution for social change to people with mental health problems. Our theoretical framework of collective citizenship, while geared toward the needs of persons with mental health problems, also contributes to recent citizenship theory on the inclusion of marginalized, stigmatised, and excluded groups. We illustrate the application of this approach through an ethnographic‐participant observation case study of a collective citizenship group with which we are associated.
Just Say No to p < x (∀x ∊ (0, 1]), *s and Other Evil Things
Authors: Hug Simon
Published: November 2019

Null hypothesis significance testing has plagued our disciplines for a longer time than is appreciated and despite of various repeated discussion the inherent problems of this approach have not been taken into consideration. Thus, a more radical change in our approach to uncertainty is necessary which also requires changes in publication decisions.
To P or not to P? The Usefulness of P‐values in Quantitative Political Science Research
Authors: Troeger Vera E.
Published: November 2019

This contribution gives a short overview over the mechanics of significance testing in inferential statistics, in particular linear models, and tries to put the discussion about the usefulness of p‐values into a broader perspective of scientific practise. This discussion needs to be embedded into the larger debate about the credibility crises faced by empirical social science research. In particular, it seems of utmost importance to discuss what the profession as a whole, journals, publishers, as well as editors can do to encourage better research practise that generates reliable and useful empirical findings.
Characterization of the novel HLA‐DPB1*04:01:42 allele by sequencing‐based typing
Authors: Cargou Marine , Elsermans Vincent , Top Isabelle , Guidicelli Gwendaline , Visentin Jonathan
Published: November 2019

HLA‐DPB1*04:01:42 differs from HLA‐DPB1*04:01:01:05 by one nucleotide substitution in codon 178 in exon 3.
Intercultural Competence for Global German Studies
Authors: Coleman Nicole , Guntersdorfer Ivett
Published: November 2019

In this conversation, two U.S.‐trained German language and culture educators discuss their approaches to intercultural communicative competence (ICC). Working in different educational settings – in a German and Global Studies program at a public university in the U.S., and at the Institute for Intercultural Communication of a German university and a study abroad program – the authors present definitions and key elements of ICC. They argue that ICC is usually not addressed in world language education. This conversation, therefore, focuses on strategies for the deliberate integration of ICC in undergraduate courses. The authors share how they incorporate ICC in language and content courses and provide concrete examples for exercises and assessment from their own teaching.
Teaching Global German Using German‐Language Cosmopolitan Tradition(s)
Authors: Pollack‐Milgate Howard
Published: November 2019

This article argues that vital resources for teaching the relationship of German and the global to advanced undergraduate language students can be found in a critical approach to the rich tradition of cosmopolitanism in canonical German‐language texts. One especially rich vein of this tradition is the historical depiction of relationships between Europe and the “Orient” from the time of the Crusades, through modernity, and into intersections with the contemporary realities of migration, global capitalism, and multinational crises. A distinctive feature of the German tradition is the attempt not only to present and problematize the contrast between “Occident” and “Orient” but to explore – even in literary texts – theoretical approaches to cultural difference. These approaches retain their validity today as conversation partners as we develop our own strategies for navigating a world caught between competing visions of the “local,” the “national,” and the “global.” By emphasizing the tension between the canon's complicity in constructing stereotypes and identities, which still haunt us today, and its advocacy for a utopian cosmopolitanism, students in these courses are prepared for both a critical appreciation of German‐language traditions as well as a historically‐based German perspective on current events.
Go Global, Build Networks, Create Nodes: Integrating the Humanities and the Professions
Authors: Finger Anke , Tracksdorf Niko
Published: November 2019

Changing public demands and decreasing enrollment numbers have challenged the traditional concept of teaching languages, cultures, and literatures in the U.S. Although nationwide enrollment numbers in German programs have been declining, “global” German Studies programs such as the ones at the University of Connecticut and the University of Rhode Island have seen an increase over the years. This article demonstrates how these programs do not only integrate world perspectives and all matters international but introduce a broader view of “global.” They go “global” in content by integrating the Humanities and the Professions on the undergraduate (UConn and URI) and graduate (UConn) level. The authors share insights into dual degree programs in German and Business, German and Engineering, and German and Diplomacy; Intercultural Communication within language and culture teaching; and Digital Humanities and Media Studies. The key for offering students these opportunities is threefold: (1) learning about and discussing topics that are relevant to the students' future career and life, (2) fostering cross‐disciplinary skills such as critical thinking and intercultural competence, and (3) establishing and nurturing relationships with other disciplines and public sectors that are reciprocal and cross‐pollinating, not exclusionary or hierarchical.
Design and field methods of the ARISE Network Adolescent Health Study
Authors: Darling Anne Marie , Assefa Nega , Bärnighausen Till , Berhane Yemane , Canavan Chelsey R. , Guwatudde David , Killewo Japhet , Oduola Ayoade , Sando Mary M. , Sie Ali , Sudfeld Christopher , Vuai Said , Adanu Richard , Fawzi Wafaie W.
Published: November 2019

The ARISE Network Adolescent Health Study is an exploratory, community‐based survey of 8075 adolescents aged 10–19 in 9 communities in 7 countries: Burkina Faso, Eswatini, Ethiopia, Ghana, Nigeria, Tanzania and Uganda. Communities were selected opportunistically and existing population cohorts maintained by health and demographic surveillance systems (HDSSs). The study is intended to serve as a first round of data collection for African adolescent cohorts, with the overarching goal of generating community‐based data on health‐related behaviours and associated risk factors in adolescents, to identify disease burdens and health intervention opportunities. Household‐based sampling frames were used in each community to randomly select eligible adolescents (aged 10–19 years). Data were collected between July 2015 and December 2017. Consenting participants completed face‐to‐face interviews with trained research assistants using a standardised questionnaire, which covered physical activity, cigarette and tobacco use, substance and drug use, mental health, sexual behaviours and practices, sexually transmitted infections, pregnancy, food security and food diversity, teeth cleaning and hand washing, feelings and friendship, school and home activities, physical attacks and injuries, health care, health status assessment and life satisfaction, as well as media and cell phone use and socio‐demographic and economic background characteristics. Results from this multi‐community study serve to identify major adolescent health risks and disease burdens, as well as opportunities for interventions and improvements through policy changes.
Are out‐of‐school adolescents at higher risk of adverse health outcomes? Evidence from 9 diverse settings in sub‐Saharan Africa
Authors: De Neve Jan‐Walter , Karlsson Omar , Canavan Chelsey R. , Chukwu Angela , Adu‐Afarwuah Seth , Bukenya Justine , Darling Anne Marie , Harling Guy , Moshabela Mosa , Killewo Japhet , Fink Günther , Fawzi Wafaie W. , Berhane Yemane
Published: November 2019

Objectives

We analysed mutually comparable surveys on adolescent attitudes and behaviours from nine sites in seven sub‐Saharan African countries, to determine the relationship between school enrolment and adolescent health outcomes.

Methods

Data from the Africa Research, Implementation Science, and Education Network cross‐sectional adolescent health surveys were used to examine the associations of current school enrolment, self‐reported general health and four major adolescent health domains: (i) sexual and reproductive health; (ii) nutrition and non‐communicable diseases; (iii) mental health, violence and injury; and (iv) healthcare utilisation. We used multivariable Poisson regression models to calculate relative risk ratios with 95% confidence intervals (CI), controlling for demographic and socio‐economic characteristics. We assessed heterogeneity by gender and study site.

Results

Across 7829 adolescents aged 10–19, 70.5% were in school at the time of interview. In‐school adolescents were 14.3% more likely (95% CI: 6–22) to report that their life is going well; 51.2% less likely (95% CI: 45–67) to report ever having had sexual intercourse; 32.6% more likely (95% CI: 9–61) to report unmet need for health care; and 30.1% less likely (95% CI: 15–43) to report having visited a traditional healer. School enrolment was not significantly associated with malnutrition, low mood, violence or injury. Substantial heterogeneity was identified between genders for sexual and reproductive health, and in‐school adolescents were particularly less likely to report adverse health outcomes in settings with high average school enrolment.

Conclusions

School enrolment is strongly associated with sexual and reproductive health and healthcare utilisation outcomes across nine sites in sub‐Saharan Africa. Keeping adolescents in school may improve key health outcomes, something that can be explored through future longitudinal, mixed‐methods, and (quasi‐)experimental studies.
Sexual behaviours among adolescents in a rural setting in eastern Uganda: a cross‐sectional study
Authors: Bukenya Justine Nnakate , Nakafeero Mary , Ssekamatte Tonny , Isabirye Nathan , Guwatudde David , Fawzi Wafaie W.
Published: November 2019

Objective

Globally as adolescents transition into adulthood, some engage in risky sexual behaviours. Such risky behaviours expose adolescents to unintended pregnancy and sexually transmitted infections (STIs), including HIV infection. Our objective was to examine sexual practices of adolescents (aged 10–19 years) in eastern Uganda and identify factors associated with having ever had sexual intercourse.

Methods

Face‐to‐face interviews were conducted using a standardised questionnaire among randomly selected adolescents residing within the Iganga‐Mayuge Health and Demographic Surveillance Site in eastern Uganda. Crude and adjusted prevalence rate ratios (PRR) were estimated using the Modified Poisson regression model to identify factors associated with adolescents having ever had sex.

Results

Of the 598 adolescents studied, 108 (18.1%) reported ever having had sexual intercourse, of whom 20 (18.5%) had ever gotten pregnant. Adolescents who reported to be out of school, 76 (12.7%), were more likely to have ever had sexual intercourse (PRR = 1.82, CI = 1.09–3.01). Females were less likely to ever have had sexual intercourse (PRR 0.69 (0.51–0.93) than males. History of ever having had sexual intercourse was associated with adolescents sexting (PRR = 1.54, CI: 1.14–2.08), watching sexually explicit films (PRR = 2.29 Cl: 1.60 ‐ 3.29) and experiencing verbal jokes about sexual intentions (PRR = 1.76, Cl: 1.27 ‐ 2.44).

Conclusions

A majority of participants reported not being sexually active; however, interventions should be required for both sexually active and not sexually active adolescents. Programmes targeted at adolescents in this and similar communities should include comprehensive sex education, and contraceptive distribution among adolescents. In particular, urgent interventions are needed to guide adolescents as they use social media.
Prevalence and risk factors associated with malnutrition among adolescents in rural Tanzania
Authors: Ismail Abbas , Darling Anne Marie , Mosha Dominic , Fawzi Wafaie , Sudfeld Christopher , Sando Mary Mwanyika , Abdallah Noor Ramadhani , Charles James , Vuai Said
Published: November 2019

Objective

To determine the prevalence and risk factors associated with malnutrition among adolescents in a rural Tanzanian community.

Methods

Cross‐sectional survey of 1226 randomly selected adolescents from the Dodoma Health and Demographic Surveillance System (HDSS) in the Chamwino district in the Dodoma region. Anthropometric measurements for weight and height were collected. Height‐for‐age‐z‐scores (HAZs) and body mass index (BMI)‐for‐age‐z‐scores (BAZs) were computed. Descriptive estimates were documented in graphs and tables, and weighted linear regression models were used to examine predictors of malnutrition.

Results

Stunting prevalence was 18%, and thinness prevalence was 14%. Overweight and obesity affected 5.23% of participants. Girls had higher HAZs (β: 0.46, 95% CI 0.33, 0.59, P < 0.0001) and BAZs (β: 0.20, 95% CI 0.05, 0.35, P = 0.0098) than boys. Age was inversely associated with HAZs (β: −0.13, 95% CI −0.17, −0.08, P < 0.0001) and BAZs (β: −0.05, 95% CI −0.10, −0.004, P = 0.0327). Wealth score (β: 0.10, 95% CI 0.04, 0.16, P = 0.0009) and dietary diversity score (β: 0.04, 95% CI 0.01, 0.07, P = 0.0080) were positively associated with HAZs and BAZs. Out‐of‐school adolescents had higher HAZs (β: −0.49, 95% CI −0.75, −0.23, P = 0.0003) and BAZs (β: −0.68, 95% CI −0.99, −0.37, P < 0.0001) than adolescents who attended school.

Conclusion

There are substantial variations of HAZs and BAZs across gender, age, education and wealth, with an emerging burden of overweight and obesity among adolescents in this rural population. Interventions are urgently required to curb both ends of the malnutrition spectrum.
Combining GAL4 GFP enhancer trap with split luciferase to measure spatiotemporal promoter activity in Arabidopsis
Authors: Román Ángela , Golz John F. , Webb Alex A. R. , Graham Ian A. , Haydon Michael J.
Published: November 2019

In multicellular organisms different types of tissues have distinct gene expression profiles associated with specific function or structure of the cell. Quantification of gene expression in whole organs or whole organisms can give misleading information about levels or dynamics of expression in specific cell types. Tissue‐ or cell‐specific analysis of gene expression has potential to enhance our understanding of gene regulation and interactions of cell signalling networks. The Arabidopsis circadian oscillator is a gene network which orchestrates rhythmic expression across the day/night cycle. There is heterogeneity between cell and tissue types of the composition and behaviour of the oscillator. In order to better understand the spatial and temporal patterns of gene expression, flexible tools are required. By combining a Gateway®‐compatible split luciferase construct with a GAL4 GFP enhancer trap system, we describe a tissue‐specific split luciferase assay for non‐invasive detection of spatiotemporal gene expression in Arabidopsis. We demonstrate the utility of this enhancer trap‐compatible split luciferase assay (ETSLA) system to investigate tissue‐specific dynamics of circadian gene expression. We confirm spatial heterogeneity of circadian gene expression in Arabidopsis leaves and describe the resources available to investigate any gene of interest.
Foreign direct investment and inequality: Evidence from China's policy change
Authors: Johansson Anders C. , Liu Dan
Published: November 2019

In this paper, we examine the impact of foreign direct investment (FDI) on local urban inequality in China. Specifically, we consider the FDI policy change as an exogenous shock on the local labour markets. We find that cities that have experienced a bigger policy change in promoting FDI between 1997 and 2002 are significantly more unequal in 2005. This pattern is mainly driven by the positive association between FDI liberalisation and skill premia. The result holds after we control for other policy changes, such as privatisation of state‐owned enterprises, infrastructure and trade liberalisation. We then turn to investigate the mechanisms using firm and individual‐level information. Our firm‐level evidence shows that FDI firms not only hire relatively more high‐skilled workers but also provide relatively higher wages to high‐skilled workers compared to domestic firms. Moreover, the individual‐level analysis shows that FDI has a significantly positive spillover effect on wages received by skilled workers employed by state‐owned enterprises, but not wages of unskilled workers.
Evaluation of cytology and histopathology for the diagnosis of canine orbital neoplasia: 112 cases (2004‐2019) and review of the literature
Authors: Flaherty Edward H. , Robinson Nicholas A. , Pizzirani Stefano , Pumphrey Stephanie A.
Published: November 2019

Objective

To provide an updated overview of canine orbital neoplasia, to compare diagnostic utility of cytology and histopathology, and to evaluate alternative sampling modalities, particularly image‐guided core needle biopsy.

Procedures

A medical records search was performed to identify dogs with orbital neoplasia. Data were collected regarding signalment, diagnosis, vision status, imaging modalities, and sample collection methods. A reference population with orbital neoplasia was also identified via literature search for comparison with regard to final diagnosis.

Results

One hundred and twelve dogs met selection criteria. In the study and reference populations, respectively, diagnoses were grouped as follows: mesenchymal tumors 40% and 35%, epithelial tumors 35% and 18%, tumors of neural origin 8% and 37%, and round cell 17% and 10%. The most common diagnoses in the study group were nasal adenocarcinoma, osteosarcoma, lymphoma, and meningioma. Cytology results were available for 47 dogs and histopathology results were available for 95 dogs. Both cytology and histopathology results were available for 30 dogs, in 53% of which results were discordant. Cytology samples were nondiagnostic or provided a diagnosis that was later overturned in 32% of cases in which they were obtained. Results from core needle biopsy samples were nondiagnostic or overturned by surgical biopsy results in only 13% of cases. No significant complications were associated with any sampling method.

Conclusions

Orbital neoplasia is common in dogs. Histopathology is superior to cytology in providing a definitive diagnosis. Image‐guided core needle biopsy appears to be a safe and effective means of obtaining samples.
Physiological basis of brief vigorous exercise to improve health
Authors: Gibala Martin J. , Little Jonathan P.
Published: November 2019

This review considers the physiological basis of brief vigorous exercise to improve health, with a focus on cardiorespiratory fitness (CRF) and glycaemic control, and the potential underlying mechanisms involved. We defined ‘brief’ as a protocol lasting ≤15 min including warm‐up, cool‐down and recovery, and involving a total of ≤5 min of ‘vigorous’ exercise, which was classified as meeting or exceeding the lower end of the range for this relative intensity as per the criteria from the American College of Sports Medicine. The physiological mechanisms responsible for the increase in CRF, as measured by maximal oxygen update (), after brief vigorous exercise are unclear and likely depend on various factors including the specific nature of the intervention as well as the time course of the response. Limited available evidence suggests the potential for an increased oxygen extraction by active muscle (i.e. greater arterio‐venous oxygen difference), since an increase in has been reported after several weeks of brief vigorous exercise despite no measurable change in cardiac output. Emerging evidence indicates that brief vigorous exercise can improve glycaemic control, suggesting that this type of exercise could potentially play a role in the prevention and management of type 2 diabetes. The acute response is not well characterized but several studies have shown that several weeks of vigorous exercise improves estimates of insulin sensitivity as determined by various methods including by hyperinsulinaemic–euglycaemic clamp. The physiological mechanisms underlying improved CRF and glycaemic control after brief vigorous exercise, and the broader impact on health, remain fruitful areas of investigation.

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Closed-Form Calculation of Lead Flank Modification Proposal for Spur and Helical Gear Stages
Authors: Weinberger Uwe , Otto Michael K. , Stahl Karsten
Published: November 2019

Due to the growing need for gearboxes to be as lightweight and efficient as possible, it is most important that the gear mesh’s potential is utilized as well as possible. One way of doing that is to define a flank modification that optimally distributes the load over the flank. Best practice for defining a flank modification is to manually check out the load distribution and to define a value of the flank modification. In general, this is an iterative method to get an optimally distributed load. This method can also be automated. To do this, the deformations of the gearbox (shafts, bearings, gear mesh) are calculated. With those results, a modification proposal is calculated and applied to the calculation model. As soon as the values for the next additional modification proposal drop under a certain limit, the iteration is finished. This method consumes time and computing power. Additionally, since it is an iteration, it does not always converge. A new method for calculating the lead flank modification for all gear stages in the gearbox to be calculated is presented in this paper. The method shown in this paper uses additional degrees of freedom and equations, which are integrated into the linear equation system of the gearbox model. Those degrees of freedom and the equations apply the boundary condition to the model of a constant load distribution. By introducing additional factors in the equations, it is possible to calculate a lead flank modification for an arbitrary load distribution. By integrating these additional degrees of freedom and the equations, only one additional calculation is needed to get a modification proposal. Examples throughout this paper show the results of this method.
3D Design Using Generative Adversarial Networks and Physics-Based Validation
Authors: Shu Dule , Cunningham James , Stump Gary , Miller Simon W. , Yukish Michael A. , Simpson Timothy W. , Tucker Conrad S.
Published: November 2019

The authors present a generative adversarial network (GAN) model that demonstrates how to generate 3D models in their native format so that they can be either evaluated using complex simulation environments or realized using methods such as additive manufacturing. Once initially trained, the GAN can create additional training data itself by generating new designs, evaluating them in a physics-based virtual environment, and adding the high performing ones to the training set. A case study involving a GAN model that is initially trained on 4045 3D aircraft models is used for demonstration, where a training data set that has been updated with GAN-generated and evaluated designs results in enhanced model generation, in both the geometric feasibility and performance of the designs. Z-tests on the performance scores of the generated aircraft models indicate a statistically significant improvement in the functionality of the generated models after three iterations of the training-evaluation process. In the case study, a number of techniques are explored to structure the generate-evaluate process in order to balance the need to generate feasible designs with the need for innovative designs.
Efficiency-Driven Design Methodology of Gerotor Hydraulic Units
Authors: Tessari Federico , Galluzzi Renato , Amati Nicola
Published: November 2019

Gerotor machines are internal gear hydraulic devices that present numerous performance benefits with respect to other topologies. For this reason, they find their application in high-efficiency mechatronic devices, such as electro-hydrostatic actuators. When designing gerotor machines either as a motor or pump, there are numerous parameters to choose, with different influences on the mechanical and volumetric efficiency behavior. Some of these aspects have been addressed in previous research works, while other important features like the tooth aspect ratio have been partially or completely neglected. Hence, it is the goal of this paper to present a methodology, as linear and generic as possible, to tackle the design of gerotor units. The proposed design method is numerically validated through a case study, where dedicated computational fluid dynamics models are used to assess the performance of the prototype.
Optimum Size of ORC Cycles for Waste Heat Recovery in Natural Gas Compressor Stations
Authors: Branchini L. , Ancona M. A. , Bianchi M. , De Pascale A. , Melino F. , Peretto A. , Ottaviano S. , Torricelli N. , Archetti D. , Rossetti N. , Ferrari T.
Published: November 2019

The paper investigates the optimum size and potential economic, energetic and environmental benefits of ORC applications, as bottomer section in natural gas compressor stations. Since typical installations consist of multiple gas turbine units in mechanical drive arrangement, operated most of the time under part-load conditions, the economic feasibility of the ORC can become questionable even though the energetic advantage is indisputable. Depending on mechanical drivers profile during the year the optium size of the bottomer section must be carefully selected in order not to overestimate its design power output. To achieve this goal a numerical optimization procedure has been implemented in the Matlab environment, based on the integration of a in house-developed calculation code with a commercial software for the thermodynamic design and off-design analysis of complex energy systems (Thermoflex). Thus the optimal ORC design power size is identified in the most generic scenario, in terms of compressors load profile, installation site conditions (i.e. ambient conditions and carbon tax value) and gas turbine models used as drivers. Two different objective functions are defined aiming at maximize the CO2 savings or the net present value. Different case studies are shown and discussed to prove the potential of the developed code. The comparison among the case studies highlights, chiefly, the influence of yearly mechanical drivers profile, part-load control strategy applied and carbon tax value on the ORC techno-economic feasibility.
Experimental and Analytical Analysis of Aero-Derivative Micro Gas Turbine Heat Transfer and Performance
Authors: Grönman Aki , Sallinen Petri , Honkatukia Juha , Backman Jari , Uusitalo Antti , Nerg Janne , Jaatinen-Värri Ahti
Published: November 2019

Small-scale gas turbines offer a light weight alternative to engine generators. Despite the many benefits of a micro gas turbine, its efficiency cannot match that of its competitors. This discrepancy is mostly due to Reynolds number losses in turbomachinery but also partly due to internal heat transfer problems, which degrade the performance below what is adiabatically expected. In general, a good understanding about the heat transfer inside the machine is of paramount importance, and innovative engineering solutions are required to improve overall performance. Overall, one of the less exploited areas in the public literature is the effect of the generator cooling approach. Small jet engines can be used as a simple and affordable foundation to produce portable aero derivative micro gas turbines for demonstrating the specific challenges they face but also to study different flow configurations. This study presents combined analytical and experimental analysis of a portable aero derivative micro gas turbine with three main objectives. The first objective is to evaluate the contributions of different heat leakage losses on the overall performance. The second objective is to compare the influence of different generator cooling approaches. And the third objective is to evaluate the effect of different technical modifications. As a result, suggestions are given about the most suitable machine layouts and the importance of several design choices.
An Investigation of the End-Notched Flexure and End-Loaded Split Tests Applied to the Mode II Interlaminar Fracture of a SiC/SiC Ceramic Matrix Composite
Authors: Presby Michael J. , Manigandan K. , Morscher Gregory N. , Godines Cody , Eftekharian Amir , Ahmad Jalees , Abdi Frank , Choi Sung R.
Published: November 2019

Delamination is a common failure mode observed in ceramic matrix composites (CMCs) and occurs as a result of applied interlaminar tensile and shear stresses exceeding the interlaminar strength. As CMCs are further implemented into aero engines the need to understand their interlaminar failure becomes increasingly important. While significant contributions have been made toward understanding the mode I fracture toughness of CMCs, limited work exists on mode II. Several test methods for measuring the mode II fracture toughness have been proposed in literature, namely the end-notched flexure (ENF) and the end-loaded split (ELS) tests. This work investigates the mode II fracture toughness of a melt-infiltrated SiC/SiC CMC at ambient temperature using the ENF and ELS test methods. Acoustic emission (AE), direct current potential drop (DCPD), and digital image correlation (DIC) are implemented as health monitoring techniques to monitor crack initiation and propagation. Results show reasonable correlation between the two test methods and that the ELS test method is better suited for characterizing R-curve behavior.
Anomaly Detection in Gas Turbine Time Series by Means of Bayesian Hierarchical Models
Authors: Losi Enzo , Venturini Mauro , Manservigi Lucrezia , Ceschini Giuseppe Fabio , Bechini Giovanni
Published: November 2019

Nowadays, gas turbines are equipped with an increasing number of sensors, of which the acquired data are used for monitoring and diagnostic purposes. Therefore, anomaly detection in sensor time series is a crucial aspect for raw data cleaning, in order to identify accurate and reliable data.

To this purpose, a novel methodology based on Bayesian Hierarchical Models (BHMs) is proposed in this paper. The final aim is the exploitation of information held by a pool of observations from redundant sensors as knowledge base to generate statistically consistent measurements according to input data. In this manner, it is possible to simulate a “virtual” healthy sensor, also known as digital twin, to be used for sensor fault identification.

The capability of the novel methodology based on BHM is assessed by using field data with two types of implanted faults, i.e. spikes and bias faults. The analyses consider different numbers of faulty sensors within the pool and different fault magnitudes, so that different levels of fault severity can be investigated.

The results demonstrate that the new approach is successful in most fault scenarios for both spike and bias faults and provide guidelines to tune the detection criterion based on the morphology of the available data.
A Novel Bulk-Flow Model for Pocket Damper Seals
Authors: Cangioli Filippo , Vannini Giuseppe , Chirathadam Thomas
Published: November 2019

In this paper a novel bulk-flow model for pocket damper seals (PDS) is introduced. The model is based on two control volumes for each circumferential pocket of the seal. The continuity, circumferential momentum and energy equations are considered for each control volume. The circumferential recirculating flow within the pocket is modelled for the first time. The boundary layer theory is used to estimate the recirculating flow area, and the Swamee-Jain friction factor correlation allows for defining the dissipation of the circumferential velocity. The perturbation method is used to solve the partial derivative governing equations in the zeroth and first-order system of equations. The rotordynamic coefficients are evaluated by integrating the dynamic pressure and rotor shear stresses along the circumferential direction.

The predictions are compared to the experimental data, which refer to test conditions representative of high-pressure centrifugal compressors. Numerical predictions are accurate for both high positive-negative inlet pre-swirl ratios. Leakage predictions are also aligned with measurements.

Finally, sealing selection approach is introduced in the paper for comparing the dynamic behaviour of two different sealing technologies and identifying stable regions as a function of the rotor natural frequency and pre-swirl ratio.
An Innovative Development of a Five-Hole Pressure Probe for Highly Unsteady Flow Phenomena
Authors: Heckmeier Florian M. , Iglesias Daniel , Kienitz Sascha , Breitsamter Christian
Published: November 2019

An advanced unsteady multi-hole pressure probe is developed in cooperation between the Chair of Aerodynamics and Fluid Mechanics of the Technical University of Munich, the probe manufacturer Vectoflow GmbH and the sensor producer fos4X GmbH. The application of additive manufacturing enables a wide variation in probe geometries. The spatial characteristics of the unsteady probe are determined in the aerodynamic calibration in a known steady uniform jet. Furthermore, the acoustic system inside the channels of the probe is investigated experimentally in the dynamic calibration. Both aerodynamic and dynamic calibration ensure an accurate reconstruction of the velocity components. Measurements of the near wake of a circular cylinder have been recorded with the unsteady probe and compared to data from the literature and corresponding hotwire anemometry measurements. Further improvements to enhance the range of applications of the probe have been initiated: This includes the miniaturization of the probe. Moreover, an unsteady differential fiber-optic sensor and its optic and passive measurement principle are introduced which shall improve the main dynamic specifications of the probe. By combining the additive manufactured pressure probe design and the novel fiber-optic sensor, more accurate measurements of high frequency flow phenomena are expected.
Modelling Axisymmetric Centrifugal Compressor Characteristics From First Principles
Authors: Powers Katherine H. , Brace Chris J. , Budd Chris J. , Copeland Colin D. , Milewski Paul A.
Published: November 2019

Turbochargers are a vital component for aiding engine manufacturers in meeting the latest emissions standards. However, their range of operation is limited for low mass flows by compressor surge. Operation in surge results in pressure and mass flow oscillations that are often damaging to the compressor and its installation. Since surge is a highly complex flow regime, full unsteady 3D models are generally too computationally expensive to run. The majority of current low-dimensional surge models use a cubic compressor characteristic that needs to be fitted to experimental data. Therefore, each time a compressor is studied using these models, costly experimental testing is required.

In this paper, a new technique for obtaining an axisymmetric centrifugal compressor characteristic is presented. This characteristic is built using the equations of mass, momentum and energy from first principles in order to provide a more complete model than those currently obtained via experimental data. This approach enables us to explain the resulting cubic-like shape of the characteristic and hence to identify impeller inlet stall as a route into surge. The characteristic is used within a quasi-steady, map-based surge model in order to demonstrate its ability to predict the onset of surge while only providing geometric data as input. Validation is provided for this model by discussion of the qualitative flow dynamics and a good fit to experimental data, especially for low impeller speeds and pressure ratios.
Spray Characteristics of Alternative Jet Fuel at Elevated Ambient Conditions
Authors: Kannaiyan Kumaran , Sadr Reza
Published: November 2019

In recent years, Gas-to-Liquid (GTL) jet fuel is considered as an alternative jet fuel because of its cleaner combustion characteristics. The chemical and physical properties of GTL fuels are different from those of the conventional jet fuels. The objective of the present work is to investigate the effect of ambient conditions and fuel volatilization characteristics on the macroscopic spray features. To this end, the macroscopic spray performance is visualized using the shadowgraph imaging technique at elevated ambient conditions. The near nozzle spray parameters like spray cone angle, sheet breakup length, and the sheet velocity, are determined from the shadowgraph images using an in-house program. The effect of ambient conditions on the near nozzle spray characteristics for conventional fuels has been reported in the literature. However, these effects have not been reported in detail for the alternative, GTL jet fuels. The results show that the ambient gas pressure has a significant effect on the spray performance when compared to that of the ambient gas temperature. At atmospheric conditions, the spray performance of GTL fuel is comparable to those of Jet A-1 fuel. However, with the increase in ambient conditions, the difference in spray performance of GTL and Jet A-1 is significant.
Effect of Tip Clearance on Rotating Stall in a Mixed-Flow Pump
Authors: Li Wei , Agarwal Ramesh K. , Zhou Ling , Li Enda , Ji Leilei
Published: November 2019

The non-uniform disturbance in the circumferential direction is the main cause for the occurrence of rotating stall in turbomachinery. In order to study the effect of tip clearance leakage flow on rotating stall, the mixed-flow pump models with different tip clearances are numerically simulated, and then the energy performance curves and internal flow structures are obtained and compared. The results show that the computed pump efficiency and the internal flow field of the pump from numerical simulation are in good agreement with the experimental results. A saddle region appears in the energy performance curves of the three tip clearances, and with decrease in tip clearance, the head and efficiency of the mixed-flow pump increase and the critical stall point shifts, and the stable operating range of the mixed-flow pump decreases, which indicates that the mixed-flow pump stalls easily for smaller tip clearance. Under the deep stall condition, the influence of the leakage flow in the end wall area increases gradually with decrease in clearance. For small clearance, the leakage flow moves away from the suction surface to some distance to form a number of leakage vortex strips with the mainstream flow and flows over the leading edge of the next blade and then flows downstream into different flow passages, generating backflow and secondary flow separation at the blade inlet, which seriously damages the spatial structure of the inlet flow. This results in the earlier occurrence of stall. With increase in clearance, the leakage vortex develops along the radial direction towards the middle of the flow channel and large flow separation occurs in the downstream channel, which induces deep stall. For 0.8mm clearance, the whole impeller outlet passage is almost blocked by the backflow of the guide vane inlet, and a deep stall is induced.