bluuebunny/crossref_metadata_2025 huggingface dataset:
From an Ordoliberal idea to a Social‐Democratic ideal? The European Parliament and the institutionalization of ‘social market economy’ in the European Union (1957‐2007)
Authors: Canihac Hugo , Laruffa Francesco
Published: December 2021

This paper explores how ‘social market economy’ became a quasi‐constitutional principle of the EU, highlighting the crucial role played in this process by the European Parliament. Based on multiple archival sources, we show that social market economy came to function as a limited repertoire: While it was advocated for various reasons by different actors, increasingly including social‐democrats, it nevertheless also solidified certain ways of conceiving the EU and its economic model. So doing, this article not only illuminates the role of the EP in the definition of a constitutionalized economic model for the EU; it also challenges the view of Europeanization as the progressive convergence around national preexisting models. Finally, two paradoxes emerge from the analysis: while supporters of the discourse of social market economy aimed at promoting the European social dimension and at addressing the EU democratic deficit, the adoption of this principle may have actually contributed to the subordination of both the ‘social’ and the ‘political’ to the ‘economic’.
Platform price parity clauses and market segmentation
Authors: Calzada Joan , Manna Ester , Mantovani Andrea
Published: December 2021

Price parity clauses (PPCs) are widely adopted by online platforms to force client sellers not to lower their prices elsewhere. We investigate under what conditions online travel agencies (OTAs) decide to apply PPCs, and how this affects hotels' listing decisions on OTAs. We find OTAs adopt PPCs when there is a sufficiently large competitive pressure in the market, either between OTAs, or between hotels (or both). PPCs allow OTAs to charge higher commission fees to hotels, which can respond by delisting from certain OTAs, thereby segmenting the market. We also find that consumers and hotels generally lose out with PPCs.
Adherence to colonoscopy in cascade screening of colorectal cancer: A systematic review and meta‐analysis
Authors: Wu Weimiao , Huang Junjie , Yang Yihui , Gu Kai , Luu Hung N , Tan Songsong , Yang Chen , Fu Jiongxing , Bao Pingping , Ying Tao , Withers Mellissa , Mao Dandan , Chen Sikun , Gong Yangming , Wong Martin C S , Xu Wanghong
Published: December 2021

Background and Aim

This study aims to systematically evaluate adherence to colonoscopy and related factors in cascade screening of colorectal cancer (CRC) among average‐risk populations, which is crucial to achieve the effectiveness of CRC screening.

Methods

We searched PubMed, Embase, Web of Science, and Cochrane Library for studies published in English up to October 16, 2020, and reporting the adherence to colonoscopy following positive results of initial screening tests. A random‐effects meta‐analysis was applied to estimate pooled adherence and 95% confidence intervals. Subgroup analysis and mixed‐effects meta‐regression analysis were performed to evaluate heterogeneous factors for adherence level.

Results

A total of 245 observational and 97 experimental studies were included and generated a pooled adherence to colonoscopy of 76.6% (95% confidence interval: 74.1–78.9) and 80.4% (95% confidence interval: 77.2–83.1), respectively. The adherence varied substantially by calendar year of screening, continents, CRC incidence, socioeconomic status, recruitment methods, and type of initial screening tests, with the initial tests as the most modifiable heterogeneous factor for adherence across both observational (Q = 162.6, P < 0.001) and experimental studies (Q = 23.2, P < 0.001). The adherence to colonoscopy was at the highest level when using flexible sigmoidoscopy as an initial test, followed by using guaiac fecal occult blood test, quantitative or qualitative fecal immunochemical test, and risk assessment. The pooled estimate of adherence was positively associated with specificity and positive predictive value of initial screening tests, but negatively with sensitivity and positivity rate.

Conclusions

Colonoscopy adherence is at a low level and differs by study‐level characteristics of programs and populations. Initial screening tests with high specificity or positive predictive value may be followed by a high adherence to colonoscopy.
The effect of religiosity on customer's response to service failure: Belief‐in‐fate, forgiveness, and emotional wellbeing
Authors: Sarofim Samer , Tolba Ahmed , Kalliny Morris
Published: December 2021

This research investigates the effect of religiosity on customers' response to service failure. In three studies, the authors provided evidence to the mediating role of belief‐in‐fate in explaining the effects of religiosity on customers' responses after service failure. The overall model religiosity → belief‐in‐fate → forgiveness → emotional well‐being is investigated in non‐social (study 1) and social (study 2) contexts of service failure. Religiosity corresponded with higher levels of belief‐in‐fate, leading to lower levels of customers' dissatisfaction (study 1) and higher levels of customer's forgiveness (study 2), both leading to a positive significant effect on consumers' emotional well‐being. To test the robustness of the model, religiosity was both measured (studies 1 and 2) and manipulated (study 3). Additionally, the moderating effect of interpersonal justice was ruled out (study 3). The effect of religiosity on belief‐in‐fate and forgiveness was not moderated by interpersonal justice. Theoretical and practical implications are discussed.
MRI and MR angiography evaluation of pulsatile tinnitus: A focused, physiology‐based protocol
Authors: Cummins Daniel D. , Caton Michael T. , Shah Vinil , Meisel Karl , Glastonbury Christine , Amans Matthew R.
Published: December 2021

Background and Purpose

Pulsatile tinnitus (PT) is the subjective sensation of a pulse‐synchronous sound, most often due to a cerebrovascular etiology. PT can severely impact quality of life and may indicate a life‐threatening process, yet a timely and accurate diagnosis can often lead to effective treatment. Clinical assessment with a history and physical examination can often suggest a diagnosis for PT, but is rarely definitive. Therefore, PT should be evaluated with a comprehensive and targeted radiographic imaging protocol. MR imaging provides a safe and effective means to evaluate PT. Specific MR sequences may be used to highlight different elements of cerebrovascular anatomy and physiology. However, routine MR evaluation of PT must comply with economic and practical constraints, while effectively capturing both common and rarer, life‐threatening etiologies of PT.

Methods

In this state‐of‐the‐art review, we describe our institutional MR protocol for evaluating PT.

Results

This protocol includes the following dedicated sequences: time‐of‐flight magnetic resonance angiography; arterial spin labeling; spoiled gradient recalled acquisition in the steady state; time‐resolved imaging of contrast kinetics; diffusion weighted imaging, and 3‐dimensional fluid‐attenuated inversion recovery.

Conclusions

We describe the physiologic and clinical rationale for including each MR sequence in a comprehensive PT imaging protocol, and detail the role of MR within the broader evaluation of PT, from clinical presentation to treatment.
Genetic diversity and population structure analysis of rice false smut pathogen in North India using molecular markers
Authors: Masurkar Prahlad , Bag Manas Kumar , Ray Anuprita , Singh Rakesh Kumar , Baite Mathew S. , Rath Prakash Chandra
Published: December 2021

False smut, caused by Ustilaginoidea virens, is one of the emerging diseases of rice in the world. The fungi show a high degree of morphological and cultural variability and produce diverse symptoms. India is a vast country with 44‐million‐ha rice production area and has only one report on genetic diversity and population analysis of U. virens from the eastern and north‐eastern region. Ten polymorphic RAPD and 21 SSR markers were used to analyse the genetic diversity and population structure of 81 isolates of U. virens from northern India, the second largest rice‐growing region. In this study, higher Polymorphic Information Content (PIC) and Quality Nature of Data (QND) data in simple‐sequence repeats (SSR) markers over random amplified polymorphic DNA (RAPD) revealed its higher efficacy; thus, SSR markers are highly informative and can help to dissect the genetic structures of U. virens. All markers yielded a total of 180 alleles with 1.0 effective alleles per loci. Genetic diversity ranged from 0.1 to 0.39. The principal coordinate analysis (PCoA), and structure analysis identified two genetic clusters of U. virens isolates with some degree of distinctness according to locations. But clusters, PCoA and structure analysis did not group the isolates according to their geographical origin and this may be due to high gene flow (Nm = 1.14).
LncRNA LOXL1‐AS1 inhibits proliferation of PDLSCs and downregulates IL‐1β in periodontitis patients
Authors: Ruan Danping , Wu Chunyun , Zhang Yu , Zhang Yu
Published: December 2021

Background

The carcinogenic role of lncRNA LOXL1‐AS1 in thoracic aortic aneurysm has been confirmed, but its role in the pathogenesis of periodontitis remains unclear. Our preliminary deep sequencing data revealed LOXL1‐AS1 downregulation in periodontitis and its inverse correlation with IL‐1β, a critical inflammatory mediator in periodontitis. This study was therefore performed to investigate the potential interaction between LOXL1‐AS1 and IL‐1β in periodontitis.

Methods

The study included 30 periodontitis patients (18 males and 12 females at the age of 34 to 44 years, with a mean of 39.3 ± 2.1 years) and 30 healthy controls (18 males and 12 females at the age of 33 to 44 years with a mean of 39.2 ± 2.0 years). The effects of LOXL1‐AS1 overexpression on IL‐1β were evaluated by RT‐qPCR and Western blot. CCK‐8 assay was used to analyze cell proliferation.

Results

LOXL1‐AS1 was downregulated in periodontitis‐affected periodontal ligament stem cells (PDLSCs) compared with healthy PDLSCs, while IL‐1β was upregulated in periodontitis‐affected PDLSCs and was inversely correlated with LOXL1‐AS1. LOXL1‐AS1 overexpression mediated IL‐1β downregulation in PDLSCs. IL‐1β treatment did not affect LOXL1‐AS1 expression. Moreover, LOXL1‐AS1 overexpression inhibited the proliferation of periodontitis‐affected PDLSCs. LOXL1‐AS1 overexpression and IL‐1β knockdown increased Bax/Bcl‐2 ratio and caspase‐3 level.

Conclusion

This study is the first to report LOXL1‐AS1 downregulation in periodontitis. Moreover, LOXL1‐AS1 might inhibit the proliferation of periodontitis‐affected PDLSCs and downregulate IL‐1β to improve periodontitis.
Attention to the COVID‐19 Pandemic on Twitter: Partisan Differences Among U.S. State Legislators
Authors: Kim Taegyoon , Nakka Nitheesha , Gopal Ishita , Desmarais Bruce A. , Mancinelli Abigail , Harden Jeffrey J. , Ko Hyein , Boehmke Frederick J.
Published: December 2021

Subnational governments in the United States have taken the lead on many aspects of the response to the COVID‐19 pandemic. Variation in government activity across states offers the opportunity to analyze responses in comparable settings. We study a common and informative activity among state officials—state legislators’ attention to the pandemic on Twitter. We find that legislators’ attention to the pandemic strongly correlates with the number of cases in the legislator’s state, the national count of new deaths, and the number of pandemic‐related public policies passed within the legislator’s state. Furthermore, we find that the degree of responsiveness to pandemic indicators differs significantly across political parties, with Republicans exhibiting weaker responses, on average. Lastly, we find significant differences in the content of tweets about the pandemic by Democratic and Republican legislators, with Democrats focused on health indicators and impacts, and Republicans focused on business impacts and opening the economy.
Rice stripe virus activates the bZIP17/28 branch of the unfolded protein response signalling pathway to promote viral infection
Authors: Li Chenyang , Zhang Tianze , Liu Yu , Li Zongdi , Wang Yaqin , Fu Shuai , Xu Yi , Zhou Tong , Wu Jianxiang , Zhou Xueping
Published: December 2021

The unfolded protein response (UPR) plays important roles in plant virus infection. Our previous study has proved that rice stripe virus (RSV) infection elicits host UPR. However, the mechanism on how the UPR is triggered upon RSV infection remains obscure. Here, we show that the bZIP17/28 branch of the UPR signalling pathway is activated upon RSV infection in Nicotiana benthamiana. We found that membrane‐associated proteins NSvc2 and NSvc4 encoded by RSV are responsible for the activation of the bZIP17/28 branch. Ectopic expression of NSvc2 or NSvc4 in plant leaves induced the proteolytic processing of NbbZIP17/28 and up‐regulated the expression of UPR‐related genes. Silencing NbbZIP17/28 significantly inhibited RSV infection. We show that RSV can specifically elicit the UPR through the bZIP17/28 branch, thus promoting virus infection of N. benthamiana plants.
The end of the dialectical symbiosis of national and tribal identities in Syria
Authors: Dukhan Haian
Published: December 2021

Since the 1970s, the Syrian regime has been attempting to build a ‘Syrian national identity’ to promote identification with the Syrian state (al hawiyya al‐wataniyya) while concurrently following policies of survival and legitimisation, to preclude suppressing tribal identity (al hawiyya al‐asha'rya). The regime instead fostered tribal identity and relied on it when confronting internal and external challenges. The Syrian regime's policies aimed to empower tribal identity, while seeking to manipulate this perception for its own ends. As a result, tribal and national identities have been integrated in a relatively harmonious way for three decades. The economic liberalisation project that Bashar al‐Assad pursued, however, disturbed the delicate balance that Hafez al‐Assad had constructed between the national and tribal identities. In the wake of the Syrian uprising, it has become clear that tribal identity was a significant element in the conflict that engulfed the country, shaping local politics and influencing social dynamics in north eastern Syria and parts of the south. Over the past few years, tribal identity has become a powerful form of expression in Syria, which is increasingly evolving to replace its national counterpart. This paper will use a constructivist approach, which argues that tribal identity has its roots in the origins of the tribes but has been subject to external manipulation by political actors in their struggles for power. In Syria, as in other states, such actions carry the risk of civil war, precipitating degrees of state failure (Hashemi, 2015) in which the tribal and national identities clash.
Adverse Tissue Reactions and Metal Ion Behavior After Small‐Head Metasul Hip Arthroplasty: A Long‐Term Follow‐Up Study
Authors: Ishida Tsunehito , Tateiwa Toshiyuki , Takahashi Yasuhito , Nishikawa Yohei , Shishido Takaaki , Masaoka Toshinori , Yamamoto Kengo
Published: December 2021

Objective

To investigate the long‐term survivorship, incidence of adverse reactions to metal debris (ARMD), and metal ion behavior in patients who underwent small‐head Metasul metal‐on‐metal (MoM) total hip arthroplasty (THA).

Methods

Between February 1998 and September 2003, a retrospective study was performed on 43 consecutive patients (43 hips) who underwent unilateral cementless Metasul MoM THAs at our institution. Of them, 35 patients (nine males and 26 females) who were available for follow‐up more than 15 years after THA were enrolled in this study and underwent metal artifact reduction sequence magnetic resonance imaging (MARS‐MRI) to identify ARMD. The mean age at surgery of the patients was 59.7 years old (range, 31–83). Clinical and radiographic outcomes were evaluated retrospectively. Clinical examinations were conducted using the Harris Hip Score (HHS). Serum cobalt (Co) and chromium (Cr) ion levels and Co/Cr ratio were assessed at different postoperative periods of <5, 5–10, 11–14, and ≥15 years.

Results

The mean follow‐up period for the 35 patients included was 18.1 years (range, 15–22). The mean HHS significantly improved from 44.6 ± 11.3 points preoperatively to 89.4 ± 7.9 points at the final follow‐up (P < 0.0001). ARMD was found in 20% of the patients using MARS‐MRI. No signs of stem loosening were found clinically or radiographically, whereas cup loosening and ARMD were observed in three patients (9%), for whom revision THAs were performed. The Kaplan–Meier survival rates with revision for any reason as the endpoint were 90.9% at 5 years, 84.8% at 10 years, 84.8% at 15 years (95% CI, 67.1–93.6), and 70.3% at 20 years (95% CI, 43.6–87.0). The survival rates with revision for ARMD as the endpoint were 100% at 5 years, 96.6% at 10 years, 96.6% at 15 years (95% CI, 77.2–99.7), and 80.1% at 20 years (95% CI, 45.3–95.2). Serum Co ion level peaked at 5–10 years after THA, which was significantly higher than that <5 years; however, it decreased to the initial level after 15 years. In contrast, serum Cr ion level significantly increased at 5–10 years and then remained almost constant. Significant differences in Cr ion levels (1.0 vs 2.0 μg/L, P = 0.024) and Co/Cr ratio (1.3 vs 0.9, P = 0.037) were found between non‐ARMD and ARMD patients at >11 years postoperatively.

Conclusion

Our results suggest that increased Cr ion levels and decreased Co/Cr ratio may be signs of ARMD in patients who underwent small‐head Metasul MoM THA.
Runners with mid‐portion Achilles tendinopathy have greater triceps surae intracortical inhibition than healthy controls
Authors: Fernandes Gabriel L. , Orssatto Lucas B. R. , Shield Anthony J. , Trajano Gabriel S.
Published: December 2021

Objectives

This study aimed to investigate short‐interval intracortical inhibition (SICI) and muscle function in the triceps surae of runners with mid‐portion Achilles tendinopathy (AT).

Methods

Runners with (n = 11) and without (n = 13) AT were recruited. Plantar flexor isometric peak torque and rate of torque development (RTD) were measured using an isokinetic dynamometer. Triceps surae endurance was measured as single‐leg heel raise (SLHR) to failure test. SICI was assessed using paired‐pulse transcranial magnetic stimulation during a sustained contraction at 10% of plantar flexor isometric peak torque.

Results

Triceps surae SICI was 14.3% (95% CI: −2.1 to 26.4) higher in AT than in the control group (57.9%, 95% CI: 36.2 to 79.6; and 43.6% 95% CI: 16.2 to 71.1, p = 0.032) irrespective of the tested muscle. AT performed 16 (95% CI: 7.9 to 23.3, p < 0.001) fewer SLHR repetitions on the symptomatic side compared with controls, and 14 (95% CI: 5.8 to 22.0, p = 0.004), fewer SLHR repetitions on the non‐symptomatic compared with controls. We found no between‐groups differences in isometric peak torque (p = 0.971) or RTD (p = 0.815).

Perspective

Our data suggest greater intracortical inhibition for the triceps surae muscles for the AT group accompanied by reduced SLHR endurance, without deficits in isometric peak torque or RTD. The increased SICI observed in the AT group could be negatively influencing triceps surae endurance; thus, rehabilitation aiming to reduce intracortical inhibition should be considered to improve patient outcomes. Furthermore, SLHR is a useful clinical tool to assess plantar flexor function in AT patients.
Protected against all odds? A mixed‐methods study on the risk of welfare sanctions for immigrants in Germany
Authors: Gschwind Lutz , Ratzmann Nora , Beste Jonas
Published: December 2021

Sanctions are payment cuts that case managers implement in order to discipline welfare recipients. Previous research suggests that immigrants face a particularly high risk to receive such reductions, primarily due to the prevalence of stereotyping in street‐level bureaucracy. The study contributes to this literature with help of a triangulation between in‐depth interviews, survey data and administrative records for the case of the German social assistance system. Our findings indicate that immigrants tend to be sanctioned at a lower rate than other benefit recipients in this context, especially if they arrived at the country only recently on grounds of international protection. This finding can be explained by the importance of reciprocity and control in the country's ‘Bismarckian’ welfare state. Our qualitative data shows that case managers exert a considerable level of agency over the implementation process. This discretion is, on the one hand, used to discipline benefit recipients who are perceived as having contributed little to the welfare system as a whole through taxes and social insurance contributions. Those who are considered to have limited control over their labour market position, on the other hand, are given a certain degree of leeway. We therefore conclude, against the background of the current street‐level bureaucracy literature, that immigration can also act as a deservingness cue in means‐tested social assistance, given that the benefit system is embedded into a welfare regime in which labour market participation, work‐testing and social insurance contributions are the dominating principles of eligibility.
Towards a sensible bifurcationism (concerning what grounds thought about particulars)
Authors: Pepp Jessica
Published: December 2021

In virtue of what are particular individuals or objects thought about? I call this thegrounding question. A consensus answer isbifurcationism: objects can be thought about in virtue of both satisfactional grounds—roughly, in virtue of their unique satisfaction of conditions that figure in a subject's thought—and non‐satisfactional grounds. Bifurcationism is a consensus view, but it comes in different flavours that correspond to different approaches to answering the grounding question. This paper draws on Saul Kripke's approach to linguistic reference in order to make recommendations about how to move toward a sensible bifurcationism concerning what grounds thought about particulars.
Bleeding outcomes of inpatients receiving therapeutic plasma exchange: A propensity‐matched analysis of the National Inpatient Sample
Authors: Soares Ferreira Júnior Alexandre , Boyle Stephen H. , Kuchibhatla Maragatha , Onwuemene Oluwatoyosi A.
Published: December 2021

Background

Although therapeutic plasma exchange (TPE) is associated with hemostatic abnormalities, its impact on bleeding outcomes is unknown. Therefore, the main study objective was to determine bleeding outcomes of inpatients treated with TPE.

Study Design and Methods

In a cross‐sectional analysis of the National Inpatient Sample (NIS), discharges were identified with 10 common TPE‐treated conditions. A 1:3 propensity‐matched analysis of TPE‐ to non‐TPE‐treated discharges was performed. The primary outcome was major bleeding and secondary outcomes were packed red blood cell (PRBC) transfusion, mortality, disposition, hospital length of stay (LOS), and charges. Multivariable regression analyses were used to examine the association between TPE and study outcomes.

Results

The study population was 15,964 discharges, of which 3991 were TPE‐ treated. The prevalence of major bleeding was low (5.4%). When compared to non‐TPE discharges, TPE had a significant and positive association with major bleeding (OR = 1.37, 95% CI: 1.16–1.63, p = .0003). TPE was also associated with PRBC transfusion (OR = 1.66, 95% CI: 1.42–1.94, p < .0001), in‐hospital mortality (OR = 1.45, 95% CI: 1.10–1.90, p = .0008), hospital length of stay (12.45 [95% CI: 11.95–12.97] vs. 7.38 [95% CI: 7.12–7.65] days, p < .0001) and total charges, ($125,123 [95% CI: $119,220–$131,317] vs. $61,953 [95% CI: $59,391–$64,625], p < .0001), and disposition to non‐self‐care (OR = 1.29, 95% CI: 1.19–1.39, p < .0001).

Discussion

The use of TPE in the inpatient setting is positively associated with bleeding; however, with low prevalence. Future studies should address risk factors that predispose patients to TPE‐associated bleeding.
Investigation of Energy Risk in Pre-Construction Stage: A Qualitative Approach
Authors: Nikman Lee Mohammad Syabilee , Mohamed Sulzakimin , Omar Roshartini , Sarpin Norliana , Shafii Haryati , Adaji Adejoh Ahmodu , Abas Muhamad Azahar
Published: December 2021

The energy demand growth every year for existing building due to the natural lifecycle of the building performance. Systematic strategy in retrofitting is proven to revamp the energy building performance. However, the retrofitting process is facing several of unknown risk as early in pre-construction stage to achieve optimum energy efficiency design strategy. The risk requires strategic assessment to minimize the impact towards the efficiency level in retrofitting. This study aims to examine the risks and the potential impact towards design strategies by conducting a semi-structured interview from six internal stakeholders in the retrofit project. The result derived from the interview revealed that there are 13 of major risks involve in retrofit project and divided into planning stage and design stage. All the risks are proven to provide a potential impact towards energy efficiency design strategies.
Heat Transfer of Turbulent Gaseous Flow in Microtubes With Constant Wall Temperature
Authors: Hong Chungpyo , Asako Yutaka , Faghri Mohammad , Ueno Ichiro
Published: December 2021

In this paper, we report on experimental results to measure the total temperature of nitrogen gas at the inlet and outlet of microtubes with constant wall temperature and to quantitatively determine the heat transfer rates. Experiments were conducted with nitrogen gas flowing in a stainless steel microtube with a diameter of 524 μm and a copper microtube with a diameter of 537 μm. The temperature differences between the inlet and the wall were maintained at 3, 5, and 10 K by circulating water around the inlet and the wall. The stagnation pressures were also controlled so that the flow, with atmospheric back pressure, could reach Reynolds numbers as high as 26,000. To measure the total temperature, a polystyrene tube with a thermally insulated exterior wall containing six plastic baffles was attached to the outlet. Heat transfer rates were obtained from the gas enthalpy difference by using the pressures and the total temperatures measured at the inlet and outlet. Heat transfer rates were also compared with those obtained from the ideal gas enthalpy using the measured total temperatures and from the Nusselt number of incompressible flows. It was found that the measured total temperature at the microtube outlet was higher than the wall temperature. Also, the heat transfer rates calculated from the total temperature difference were higher than the values obtained from the incompressible flow theory.
Planar Compliance Realization With Two 3-Joint Serial Mechanisms
Authors: Huang Shuguang , Schimmels Joseph M.
Published: December 2021

In this paper, the realization of any specified planar compliance with two 3R serial elastic mechanisms is addressed. Using the concept of dual elastic mechanisms, it is shown that the realization of a compliant behavior with two serial mechanisms connected in parallel is equivalent to its realization with a 6-spring fully parallel mechanism. Since the spring axes of a 6-spring parallel mechanism indicate the geometry of a dual 3R serial mechanism, a new synthesis procedure for the realization of a stiffness matrix with a 6-spring parallel mechanism is first developed. Then, this result is extended to a geometric construction-based synthesis procedure for two 3-joint serial mechanisms.
Effective Clearance and Differential Gapping Impact on Seal Flutter Modeling and Validation
Authors: Corral Roque , Greco Michele , Vega Almudena
Published: December 2021

This paper presents an update of the model derived by Corral and Vega (2018, “Conceptual Flutter Analysis of Labyrinth Seal Using Analytical Models. Part I—Theoretical Support,” ASME J. Turbomach., 140(12), p. 121006) for labyrinth seal flutter stability, providing a method of accounting for the effect of dissimilar gaps. The original Corral and Vega (CV) model was intended as a conceptual model for understanding the effect of different geometric parameters on the seal stability comprehensively, providing qualitative trends for seal flutter stability. However, the quantitative evaluation of seal flutter and the comparison of the CV model with detailed unsteady numerical simulations or experimental data require including additional physics. The kinetic energy generated in the inlet gap is not dissipated entirely in the inter-fin cavity of straight-through labyrinth seals, and part is recovered in the downstream knife. This mechanism needs to be retained in the seal flutter model. It is concluded that when the theoretical gaps are identical, the impact of the recovery factor on the seal stability can be high. The sensitivity of the seal stability to large changes in the outlet to inlet gap ratio is high as well. It is concluded that fin variations due to rubbing or wearing inducing inlet gaps more open than the exit gaps lead to an additional loss of stability concerning the case of identical gaps. The agreement between the updated model and 3D linearized Navier–Stokes simulations is excellent when the model is informed with data coming from steady Reynolds-averaged Navier–Stokes simulations of the seal.
Combined Cycle Powerplant Cost Sensitivity Analysis
Authors: Nanadagopal Pugalenthi , Pandey Animesh , More Manjunath , Kamboj Pertik
Published: December 2021

In Gas turbine-based combined cycle power plant market, the customer conducts an economic evaluation of competitive products to decide their buying option. There are different methods to calculate the economics of a power plant like Levelized cost of electricity (LCOE), Net present value (NPV) and payback period.

LCOE methodology is commonly used for lifecycle cost analyses for combine cycle power plant that covers cost details of the plant and plant performance over the complete lifetime of a power plant from construction to retiring. Typically, it includes a combine cycle power plant ownership costs (Total plant cost and operating & maintenance cost) and combine cycle power output and efficiency. This LCOE method is helpful to compare power generation system that use similar technologies.

This paper encompasses the LCOE calculation method, assumptions & approach to analyze the impact of key parameters of the electrical generation cost. They key parameters includes combine cycle output, combine cycle efficiency, fuel cost, annual operating hours, capital charge factor, annual operating hours, power plant life, discount rate, nominal escalation rate, operating & maintenance cost. This paper analyses result will provide insights to the customer & Gas turbine-based OEM (Own Equipment Manufacturing) companies to focus on different area/parameters to reduce the unit cost of generating electricity.
Experimental and Modeling Studies on the Stress Relaxation Behaviour of Ti-6Al-4V Alloy
Authors: Prasad Kali , Hariharan Krishnaswamy , K. Banerjee Dilip
Published: December 2021

The transient mechanical behavior of materials during stress relaxation has evoked interest in manufacturing applications because of the effect of stress relaxation on formability enhancement. However, most of the previous studies have focused on advanced high strength steels and aluminum alloys. Limited transient stress relaxation studies have been conducted on titanium alloys in order to understand the influence of stress relaxation on forming behavior. Titanium alloys are widely used in aerospace components because of their high strength to weight ratios and excellent fatigue strengths. However, room temperature formability of Ti alloys is an important concern, which restricts their widespread use in various applications. To address these challenges, the present study is aimed to understand the role of transient stress relaxation on formability of Ti alloys. Toward this end, stress relaxation of a dual phase titanium alloy (Ti-6Al-4V) has been investigated experimentally. Stress relaxation tests were performed by interrupting uniaxial tensile tests in the uniform deformation regime for a pre-defined strain and hold time after which tests were continued monotonically until fracture. Single step, room temperature stress relaxation experiments were performed systematically to study the effect of hold time, pre-strain, and strain rate on mechanical properties. The stress relaxation phenomenon was found to contribute positively to the ductility improvement. The mechanisms responsible for enhancing the formability are discussed. The experimentally obtained stress vs. time data were analyzed using a advanced constitutive model for stress relaxation available in literature.
Comprehensive Review & Enhancements on Probe Substitution Techniques for Faulty Steady State Inlet Pressure Distortion Data
Authors: Rajendrakumar Mithilesh , Vyas Manu , Deshpande Prashant , Balasubramanian Bommaian , Shepherd Kevin
Published: December 2021

When a gas-turbine engine is in operation, inlet-generated total-pressure distortion can have a detrimental effect on engine’s stability and performance. During the product development life cycle, on-ground wind tunnel tests and in-flight tests are performed to estimate the inlet distortion characteristics. Extensive measures are taken in the preparation and execution of inlet distortion tests. The data pertaining to spatial inlet distortion is recorded using an array of high-response total-pressure probes. The pressure probes are usually arranged in rake and ring arrays as per AIR1419. The data from these probes is used by propulsion system designers to address the effects of inlet distortion on stability and performance, particularly the engine’s sensitivity to inlet distortion. In some instances, the probes can produce inaccurate measurements or no measurements at all, due to a variety of reasons. This may result in a time consuming and costly process of repeating the test. To avoid this, the inaccurate or invalid measurements can be substituted using a variety of statistical techniques during test data post-processing. This paper discusses the results of different interpolation techniques to substitute invalid steady-state total-pressure measurements, evaluated in the context of classical distortion profile data available in AIR1419. The techniques include 1D linear interpolation using only probes data from adjacent rings, 1D linear interpolation using only probes data from adjacent rakes, and bilinear interpolation using probes data from adjacent rings and rakes. Furthermore, the paper evaluates a bilinear interpolation technique with optimal weights obtained from linear regression, that enhances the estimation of invalid pressure values.
Influence of Degradation, Fuel Cost and Electricity Price Factors on Combine Cycle Power Plant Cost Analysis
Authors: Nanadagopal Pugalenthi , Duerr Matthias , Fahrendorf Ole , Haid Dan , Paprotna Hubert
Published: December 2021

Gas turbine-based combine cycle (GT-CC) economic evaluation is very important to bring together own equipment manufacturing companies (OEM’s) and power plant owners. The fuel cost & cost of electricity play the major role in economic evaluation which drives the decision during the bidding.

The first portion of this paper encompasses the different cost analysis methods like Net Present Value (NPV), Internal Rate of Return (IRR), Levelized Cost of Electricity (LCOE) and Pay Back Period (PBP) for different fuel costs and electricity prices.

The second portion of the paper covers the delta cost benefits due to improvement in the combined cycle degradation GT-CC operators or customers are looking for the opportunities to control and minimize the degradation of the gas turbine power plant which directly impact the profitability. The customer or operator always monitor the plant performance to understand the life cost impact on performance degradation.

This paper will help the customers & GT-CC OEM companies to focus on different area to reduce the unit cost of generating electricity, decide to move forward with the project during the proposal and improve the business at various regions based on fuel cost and global geographical political situations. Also, the reader can digest the benefits of improved degradation curve over the normal curve.
Effect of Corrosion Pit on the Structural Characteristics of Foil Journal Bearings
Authors: Mourya Vishal , Bhore Skylab P.
Published: December 2021

Due to corrosive environment, material loss in a localized area leads to formation of a corrosion pit. It diminishes the structural integrity and performance of product. To predict and analyze the effect of corrosion pit on the performance of gas foil bearings (GFBs), FEM analysis of bump-type GFBs is carried out. The effect of corrosion pit is investigated for three different shapes: circular, square and triangular. In this study, the FEM analysis of bump-type GFBs is performed in ANSYS software. Firstly, the influence of a corrosion pit is analyzed for various shapes under different pressure loading. These results show that the presence of a corrosion pit developed high-stress crack intensity, which can result in crack initiation in foil bearings. As pressure loading increased, the stress crack intensity in foil bearings increased. Among different pit shapes, the circular pit shape induces the maximum stress crack intensity in foil bearings, which shows that the crack initiation in foil bearings is observed for a circular pit. Then, the influence of a corrosion pit on the structural stiffness of foil bearings is evaluated for various foil materials under different friction coefficients. These results show that the influence of friction coefficient in foil bearings is increased within the presence of a corrosion pit.
Sensitivity of the Spool Rate on the Dynamic Response of the System
Authors: Das Arnab , Iyappan Praveen , Chinthapally Srinivas , Kumar Avinash
Published: December 2021

In rotodynamic systems, the rotor is spooled up from zero speed to its operating speed during the engine start. One of the considerations in design of rotating systems is the placement of rotor critical speed. It is vital to ensure that the rotor critical speeds are not close to the engine operating speed. However, it is not always possible to isolate all the frequencies above the operating speed. So, during the engine start to full speed, rotor system does travel through the mode. Therefore, to avoid a large system response, the rotor is spooled up quickly through the critical speed. In addition to the rotor critical speeds, the natural frequencies of the static structures may also get excited during the rotor spool up and spool down. The static structure response is one of the important considerations in designing a system for dynamic loading condition. It has been observed that the rotor spool rate affects the static structure response. This paper focuses on effect on system’s response under various spool rate. It has also been shown that the natural frequency of the system and damping in the system are two of the major factors towards sensitivity of system response with spool rate. Additionally, it has been observed that the presence of non-linearities shifts the peak response away from the natural frequency depending on the spool rate and spool direction.
Machine Learning Based Classification Model for Predicting Cyclic Failure in Radially Cooled Gas Turbine Blades
Authors: Shrivastava Rishabh , Kapoor Ankush , Kaushal Stuti , Yadav Amit , Vodnala Pavankumar
Published: December 2021

Gas turbine blades and vanes face very severe operating conditions - high temperature and pressure which necessitates the creation of complex cooling and component designs, resulting in high computational cost. The ability to predict cyclic failure in these components is therefore a critical activity that has been historically performed using 3D commercial finite element (FE) codes for baseload conditions. However, these codes take substantial time and resources which restricts their application in failure prediction at variable operating conditions. Newer data-driven techniques such as machine learning (ML) provide a valuable tool that can be utilized to predict the occurrence of cyclic failure for these conditions with minimal time and resource requirement.

In this paper, a machine learning based surrogate model is developed to predict the cyclic failure of a radially cooled turbine blade. The features used as input to machine learning model are turbine inlet temperature, coolant inlet temperature, hot gas mass flow rate, cooling air mass flow rate and blade materials. The output for the model is a binary variable depicting the incident of component failure. 70% of the FE data points are used to train the ML model while the remaining are used for testing. A comparative study between Logistic Regression, Random Forest, K-nearest neighbor, and Support Vector Machine (SVM) was performed to select the most accurate algorithm for the classification model. Finally, the results show that the Random Forest and SVM algorithms predicts failure with the highest f-1 score of 0.92. The model also demonstrates that Turbine Inlet temperature has the highest importance amongst the input features followed by blade material. Additionally, this methodology offers a tremendous advantage for failure prediction by reducing analysis time from multiple hours to a few seconds, rendering this technique especially beneficial for time sensitive business decisions in the gas turbine industry.
Dynamic Modelling and Free Vibration Characteristics Analysis of Rotating Beams
Authors: Sachin D. , Reddy Mallikarjuna
Published: December 2021

Turbine blades are ideally modeled as cantilever beams on a disc rotating at a constant angular velocity. A study is made to understand the dynamic relationships between a rotating cantilever beam and various factors like hub radius, rotation speed, and slenderness ratio in in-plane vibration (Chordwise motion) and out-of-plane vibration (Flapwise motion). Hub is assumed to be rigid in the study. Using Hamilton’s principle, governing differential equations of movement for free vibration analysis of Euler-Bernoulli beam (EB) and Timoshenko (TB) beam under rotation are derived. The effects of the Gyroscopic couple are taken into account in the equations. The beam model is discretized using the Finite element approach. Derived differential equations are transformed into dimensionless quantities in which dimensionless parameters are identified. Under rotation, it is observed that the natural frequencies increase with the increase in rotational speed for both flapwise and chordwise motions of the beam. An interesting phenomenon is observed in the chordwise motion results, where Natural frequencies veer off at certain rotational speeds and certain modes. Slenderness ratios also influence this phenomenon, which shifts the veer-off region and the tuned angular frequency. Numerical results are obtained for different rotational speeds with various hub radius ratios, and it was observed that hub radius directly influences the natural frequencies of the rotating uniform cantilever beam. A thorough study on the influence of the slenderness ratio showed that, for lower slenderness ratio, frequency veering region occurs at the fundamental natural frequency, but for higher slenderness ratios’ there is a shift in frequency veering region for higher modes.
Coupled Thermal-Structural Analysis of Generator For sCO2 Turbomachinery
Authors: Guntanur Ramesha , Patel Ashutosh , Biradar Vijay , Kumar Pramod
Published: December 2021

This paper presents the coupled thermal and structural analysis of the rotating components of the generator using ABAQUS finite element solver. The interference between shaft and rotor is optimized to have a positive contact pressure and also minimize the stresses in the laminate at all operating speeds. Thermal analysis is performed to simulate the temperature distribution arising from the heat losses of generator. The flow path of the coolant is designed through the shaft to minimise the temperature rise of the generator. The resulting changes in the contact pressure between laminated disc and shaft is computed using sequentially coupled thermal and structural analysis. The thermal stresses of rotor are computed estimated and the design is optimized for transmitting torque at different operating speeds.
Preliminary Aerodynamic Design of a S-CO2 Axial Turbine
Authors: Kumaran R. Senthil , Alone Dilipkumar B. , Nassar Abdul , Kumar Pramod
Published: December 2021

Axial turbines are gaining prominence in supercritical carbon-di-oxide (S-CO2) Brayton cycle power blocks. S-CO2 Brayton cycle power systems designed for 10 MW and upwards will need axial turbines for efficient energy conversion and compact construction. The real gas behavior of S-CO2 and its rapid property variations with temperature presents a strong challenge for turbomachinery design. Applying gas and steam turbine philosophies directly to S-CO2 turbine could lead to erroneous designs. Very little information is available in the open literature on the design of S-CO2 axial turbines. In this paper, design of a 10 MW axial turbine for a simple recuperated Brayton cycle waste heat recovery system is presented. Three repeating stages with nominal stage loading coefficient of 2.3 and flow coefficient of 0.37 were designed. An axial turbine mean-line design method tuned to S-CO2 real gas fluid medium is discussed. 3D blade design was made suing commercial turbomachinery design software AxSTREAM. The turbine was designed for inlet temperature of 818.15 K, pressure ratio of 2.2, rotational speed of 12000 rpm and mass flow rate of 104.5 kg/s. 3D CFD simulations were carried out using the commercial RANS solver ANSYS CFX 2020 R2 with SST turbulence model for closure. S-CO2 was modelled as real gas with Refrigerant Gas Property tables generated over the appropriate pressure and temperature ranges using NIST Refprop database. CFD studies were carried out over a range of mass flow rates and speeds, covering the design and several off-design conditions. The performance maps generated using 3D CFD simulations of the turbine are presented. The geometrical parameters obtained with the mean-line design matched well with that of the 3D turbine design arrived using AxSTREAM. It was observed that the turbine produced 10 MW power at the design condition while passing the required mass flow. CFD studies also showed that the preliminary turbine design achieved a moderate total-to-total efficiency of 80 % at the design condition. The design has potential for further optimization to obtain improved efficiency and for reducing the number of stages from three to two.
A review of the genus Primotydeus (Acariformes: Tydeoidea: Iolinidae)

Authors: Kazmierski Andrzej , Laniecka Izabella , Laniecki Ronald
Published: December 2021

A supplementary diagnosis of the genus Primotydeus André, 1980 is presented together with a review of all the species. Three of them, Primotydeus talpae, P. festucae and P. giselae are figured and described as new for science. Another one, Oakvillea eglalea Momen et Sinha, 1991 is transferred to the genus Primotydeus and consequently transferred from the family Tydeidae, subfamily Tydeinae to the family Iolinidae, subfamily Tydaeolinae. Lastly, a key to the species of Primotydeus is given.
Contribution to the knowledge of the oribatid mite genus Cultrobates (Acari, Oribatida, Ceratokalummidae), with description of a new species from Peru

Authors: Ermilov Sergey G. , Subias Luis S. , Shtanchaeva Umukusum Ya. , Friedrich Stefan
Published: December 2021

Description of a new species of oribatid mite (Oribatida) of the genus Cultrobates (Ceratokalummidae)—C. lehmanni sp. nov.—is presented, based on materials collected from upper soil and leaf litter in the primary evergreen lowland rainforest of Amazonian Peru. Summarized generic traits, distribution and habitats of all known species of Cultrobates are presented. An identification key to known Ceratokalummidae species is provided.