Stability Factor Research Articles

Optimised and percolated nanocomposite of polyaniline/tungstic anhydride modified electrode implemented in Vanadium redox flow battery

In order to make vanadium redox flow batteries (VRFB) economically viable on a large scale, it is crucial to create graphite-based electrode nanomaterials with an excellent performance. In this research work, we synthesized the various percentage nanocomposites of polyaniline (PANI)/nano-tungsten oxide (NTO) by in situ chemical oxidative polymerization method. The impact of crystal phases, elements present in nanocomposites, thermal stability, surface analysis, and morphological factors were studied. We investigated electrochemical behavior such as cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and Tafel studies for PANI and NTO and prepared nanocomposites (NPATO) with different proportions sprayed over graphite felt (GF). Characterization analysis was used to examine the impact of various NTO loading concentrations on the PANI, and an ideal best percolated sample NPATO20/GF (3 mg cm−2) was inserted as a positive electrode in the cell stack to examine the charge–discharge cycles. At 60 mA cm−2 current density, their coulombic (η C), voltaic (η V), and energy (η E) efficiencies are outstanding. The concentration of 3 mg cm−2 nanoparticles on GF provided sufficient availability of active sites for electrochemical reactions, resulting in an increased electrochemical reaction. It has been proven that this work creates an affordable and efficient method for the forthcoming VRFBs.

Network specificity decreases community stability and competition among avian haemosporidian parasites and their hosts

AbstractAimParasites play a fundamental role in shaping ecological communities and influencing trophic interactions. Understanding the factors that drive parasite impacts on community structure and stability (i.e. resilience to disturbances) is crucial for predicting disease dynamics and implementing effective conservation strategies. In this study, using avian malaria and malaria‐like parasites as a model system, we investigated the relationship between specificity, community stability and parasite vulnerability and their association with host diversity and climate.LocationGlobal.Time period2009–2023.Major taxa studiedAvian malaria and malaria‐like parasites.MethodsBy compiling occurrence data from a global avian haemosporidian parasite database (MalAvi), we constructed a comprehensive dataset encompassing 60 communities. We utilized a phylogenetic model approach to predict missing host–parasite interactions, enhancing the accuracy of our analyses. Network analyses based on bipartite interactions provided measures of network specificity, stability, modularity, parasite competition and vulnerability to extinction.ResultsWe found that the high network specificity reduced community stability and decreased competition among parasites. Furthermore, we found that parasite vulnerability decreased with increasing community stability, highlighting the importance of community stability in host–parasite interactions for long‐term parasite persistence. When exploring the influence of local host diversity and climate conditions on host–parasite community stability, we demonstrated that increasing host biodiversity and precipitation reduces parasite competition. Conversely, higher temperature raises competition among parasites.ConclusionThese findings provide valuable insights into the mechanisms underlying parasite impacts on communities and the interplay between specificity, community stability and environmental factors. Further, we reveal the role of climate in shaping host–parasite interactions. By unravelling the complexities of parasite‐mediated interactions, our research substantially improves the current knowledge of the importance of specificity as a modulator of interactions in bipartite networks.

Exploring trends and determinants of basic childhood vaccination coverage: Empirical evidence over 41 years.

Vaccination is widely considered to be one of the most important prevention measures as a health strategy. This paper examines trends in basic childhood vaccination coverage and which country and time-dependent determinants may have influenced childhood immunization rates (1-dose BCG, 1- and 3-dose DTP (diphtheria, tetanus, pertussis), 1-dose measles, and 3-dose polio) between 1980 and 2020 across 94 countries. We identify economic, inequality, demographic, health, education, labor market, environmental, and political stability factors of immunization. To do this, we use data from the annual WHO and United Nations International Children's Emergency Fund (UNICEF) coverage estimates. The empirical analysis consists of generalized estimating equation models to assess relationships between immunization rates and socioeconomic factors. Additionally, we follow the Barro and Sala-i-Martín approach to identify conditional convergence. Our findings show the strongest positive statistically significant association between immunization rates and GDP per capita, as well as births attended by skilled health staff. Moreover, our research demonstrates conditional convergence, indicating that countries converge towards different steady states. The present study brings new insights to investigating the determinants of childhood vaccination coverage and provides significant implications for health policies.

Experimental Study on the Effect of Wind on Armor Stone Stability

Wind is a significant factor influencing the stability of breakwater armor stones. However, few existing studies have considered the effects of wind on these structures. In this study, two-dimensional laboratory experiments were conducted to examine the effect of wind on the stability of breakwater armor stones. The stability factor (KD) of the armor stone, fluid velocity, runup, and rundown were observed under the action of waves and winds. A wind turbine was installed in front of the physical model of the breakwater to generate extreme wind conditions of 5.5 and 12 m/s. The results showed that KD decreased by 42.18% at 5.5 m/s and 57.82% at 12 m/s compared with that without wind. The maximum runup and rundown heights increased with wind velocity, following a Rayleigh distribution. The fluid velocity distribution conformed to a normal distribution, with the mean velocity directed offshore. Many studies have suggested that runup, rundown, and fluid velocity are the main factors affecting the stability of breakwater armor stones. The analysis revealed that wind affects these factors and lowers the stability coefficient. These wind-induced hydrodynamic changes suggest the need for a detailed hydrodynamic review of wind-wave conditions.

Exploring the associations of demographics and scale measures with cognitive driving behavior among older drivers in China

Age-related changes and frailty are reasons for the high proportion of older drivers in certain types of crashes, such as giving right of way at intersections and turning left. The identified crash causes include the driver’s demographics, driving style, cognitive function, and mental workload. This study aimed to explore the associations of demographics and scale measures with cognitive driving behavior. Thirty-nine drivers, consisting of twenty younger drivers (18–60 years old) and nineteen older drivers (above 60 years old), participated in driving simulation experiments after completing scale tests. The selected scale measures included the demographic questionnaire, Multidimensional Driving Style Inventory (MDSI-C), Mini-Mental State Examination (MMSE), Trail Making Test Part A (TMT-A) and Part B (TMT-B), and the National Aeronautics and Space Administration Task Load Index (NASA-TLX) for obtaining subjective information from drivers. Driving scenarios were developed based on the driving characteristics of older adults to investigate age-related driving ability. The driving behavior parameters included reaction time, lateral stability, and driving speed, corresponding to reaction, perception, and execution. Three stepwise regression models showed that NASA-TLX, the interaction between age and driving experience, and the interaction between age and TMT-A significantly explained 53.3 % of reaction time variance; TMT-A, risk driving style, anxiety driving style, and gender significantly explained 53.5 % of lateral stability variance; TMT-A, NASA-TLX, and MMSE significantly explained 60.6 % of driving speed variance. Subsequently, the impact of four age-related predictor variables on driving behavior was further discussed. It is worth noting that a rich driving experience may compensate for driving performance. However cognitive impairment impairs this compensation. Driving behavior is influenced by a combination of various factors. Age, as a physiological indicator, is not sufficient to be a strong predictive factor for lateral stability and driving speed. The results provide a reference for traffic safety management departments to streamline driving suitability test procedures and propose targeted training methods for older drivers.

Thermodynamic analysis for the dissolution of two similar amino acids in sodium sulfate aqueous solution

In the current work, the analyti cal static gravimetric technique was used to assess the solubilities of DL-α-amino butyric acid and DL-valine in an aqueous binary solvent mixture of sodium sulfate (Na2SO4) under equilibrium saturation conditions in between temperature range 288.15 and 308.15 K. Different thermodynamic factors along with transfer Gibbs energetics and entropies under standard conditions were estimated by using computational as well as theoretical method by using the experimental solubilities. Several modes of interactions that occur during solvation were also explained. The manner that solvent molecules of solute amino acids are surrounded in the aforementioned medium employed during the process is taken into consideration. Amino acids become more soluble as the temperature rises. The study also helps us to reach the conclusion that physical properties of electrolyte (Na2SO4), mixed solvent, and the size of the amino acids’ molecules are the main governing factors for the chemical stability as well as other thermodynamic and physical property like solubility of solute amino acids.

Thermo-environmental multi- investigation and ANN-based optimization of a novel heat integration criteria system integrated with a marine engine generating liquefied hydrogen

Marine transportation is a significant contributor to overall energy consumption among transportation sectors and is responsible for producing a considerable amount of greenhouse gases. A potential solution for alternative applications involves implementing combined heat integration, thereby enabling the production of additional utilities and mitigating emissions. The current work introduces an innovative heat integration process for a marine engine, focusing on implementing an optimal thermal matching technique to minimize overall irreversibility in producing liquefied hydrogen and coolant. The process incorporates an organic flash-bi-evaporator cooling cycle, a humidification dehumidification desalination, a polymer electrolyte membrane water electrolysis process, and a Claude cycle. The generated freshwater is delivered to the electrolyzer to produce gaseous hydrogen. This product and the cooling for freezing are utilized in the Claude cycle for hydrogen liquefaction. The study utilizes an advanced thermo-environmental multi-criteria investigation and optimization, considering sensitivity analysis and optimization based on artificial intelligence method. The optimization process incorporates the training and testing of artificial neural networks, NSGA-II method, and TOPSIS decision-making. The primary objective functions include exergetic efficiency and carbon dioxide emission. The findings demonstrate that the specified objectives are computed to be 0.121 and 2.67 kg/MWh, correspondingly. Besides, this condition exhibits a liquefied hydrogen flow rate of 6.44 L/h and a cooling output of 43.61 kW, showing an energy efficiency of 0.1145. Also, the total exergy destruction rate associated with the arranged structure is 124.5 kW. Furthermore, the optimum state reveals an exergoenvironmental index of 0.840 and an exergetic stability factor of 0.869.

Both local stability and dispersal contribute to metacommunity sensitivity to asynchronous habitat availability

The stability of isolated communities depends on the complexity of their foodwebs. However, it remains unclear how local stability interacts with dispersal in multitrophic metacommunities to shape biodiversity patterns. This lack of understanding is deeper in the more realistic frame of landscapes that exhibit non-trivial and time-varying structures. Therefore, in this study, we aim to evaluate the influence of local stabilizing factors versus dispersal in determining the sensitivity of metacommunity biodiversity to increasing asynchrony of site availability. Additionally, we assess the role of foodweb complexity and landscape structure as modulating factors. To accomplish our goals we developed a model based on random matrices for local communities, which are linked by stochastic dispersal over explicit dynamic landscapes. We ran numerical simulations and computed the effect sizes of foodweb temperature, self-limitation, dispersal ability, and all pairwise combinations, on the sensitivity of biodiversity to landscape asynchrony. In our experiments we explored gradients of species richness, foodweb connectance, number of sites, and landscape modularity. Our results showed that asynchrony among site availability periods reduced α\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\alpha$$\\end{document}-diversity and increased β\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\beta$$\\end{document}-diversity. Asynchrony increased γ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\gamma$$\\end{document}-diversity at high dispersal rates. Both local and regional stabilizing factors determined the sensitivity of metacommunities to landscape asynchrony. Local factors were more influential in landscapes with fewer sites and lower modularity, as well as in metacommunities composed of complex foodwebs. This research offers insights into the dynamics of metacommunities in dynamic landscapes, providing valuable knowledge about the interplay between local and regional factors in shaping ecological stability and species persistence.

B-cells in pulmonary arterial hypertension: friend, foe or bystander?

There is an unmet need for new therapeutic strategies that target alternative pathways to improve the prognosis of patients with pulmonary arterial hypertension (PAH). As immunity has been involved in the development and progression of vascular lesions in PAH, we review the potential contribution of B-cells in its pathogenesis and evaluate the relevance of B-cell-targeted therapies. Circulating B-cell homeostasis is altered in PAH patients, with total B-cell lymphopenia, abnormal subset distribution (expansion of naïve and antibody-secreting cells, reduction of memory B-cells) and chronic activation. B-cells are recruited to the lungs through local chemokine secretion, and activated by several mechanisms: 1) interaction with lung vascular autoantigens through cognate B-cell receptors; 2) costimulatory signals provided by T follicular helper cells (interleukin (IL)-21), type 2 T helper cells and mast cells (IL-4, IL-6 and IL-13); and 3) increased survival signals provided by B-cell activating factor pathways. This activity results in the formation of germinal centres within perivascular tertiary lymphoid organs and in the local production of pathogenic autoantibodies that target the pulmonary vasculature and vascular stabilisation factors (including angiotensin-II/endothelin-1 receptors and bone morphogenetic protein receptors). B-cells also mediate their effects through enhanced production of pro-inflammatory cytokines, reduced anti-inflammatory properties by regulatory B-cells, immunoglobulin (Ig)G-induced complement activation, and IgE-induced mast cell activation. Precision-medicine approaches targeting B-cell immunity are a promising direction for select PAH conditions, as suggested by the efficacy of anti-CD20 therapy in experimental models and a trial of rituximab in systemic sclerosis-associated PAH.

Comprehensive analysis of a high temperature solar powered trigeneration system: An energy, exergy, and exergo-environmental (3E) assessment

In the present work, helium serves as the primary working fluid within the supercritical Brayton cycle, employed to generate power through a solar power tower system. The conventional Brayton cycle for recovering the wasted heat is combined with a cascaded vapor absorption-compression refrigeration system to increase the overall system’s performance. Additional benefits of this integrated system include the ability to supply enhanced heating and cooling for food storage applications at lower temperatures. A comprehensive analysis of the combined system was conducted based on exergy, energy, and exergo-environmental (3E) factors a using computational technique engineering equation solver. The combined system’s energy, exergy efficiency, and power output were determined to be 28.82%, 39.53%, and 14.865 kW, respectively. The coefficient of performances for cooling and heating were observed as 0.5391 and 1.539 respectively. Approximately 78.18% of the total exergy destruction within the entire plant can be attributed to the solar subsystem, which amounts to 22.763 kW. As direct normal irradiance rises, the environmental impact index decreases from 1.6504 to 0.6801, while the system’s environmental stability factor improves, increasing from 0.3773 to 0.5952. Moreover, the parametric assessment highlights the substantial influence of heliostat and receiver efficiencies, as well as the helium turbine’s inlet temperature, on the trigeneration system’s performance. In addition, compared to previously published research, the current proposed system outperforms supercritical CO2 cycle systems and the conventional steam Rankine cycle systems.

Effects of Buffer and Capping Layers on Thermal Stability of CoFeB/MgO Frames at Various Temperatures

The utilization of CoFeB thin films in spintronic devices has attracted significant attention due to their exceptional magnetic properties, which include high saturation magnetization and spin polarization. However, the effect of ambient temperature on the magnetic properties of CoFeB/MgO frames, particularly those with different buffer and capping layers, remains unexplored. Therefore, in this study, the magnetostatic and dynamic properties of CoFeB/MgO frames were investigated at various temperatures. Using vibrating sample magnetometry and ferromagnetic resonance spectroscopy, changes in key parameters such as saturation magnetization, the Gilbert damping constant, magnetic anisotropy field, in-plane uniaxial magnetic anisotropy energy, and thermal stability factor were investigated. Furthermore, the thermal stabilities of CoFeB/MgO frames with Ta buffer and capping layers were compared with those of CoFeB/MgO frames with W buffer and capping layers by examining the changes in the key parameters at various temperatures. These results reveal that the thermal stability of the latter surpassed that of the former. This study provides significant insights for the development of thermally robust spintronic devices capable of operating above room temperature.

Impact of Self-Management on the Quality of Life of Patient with Diabetes Mellitus: A Systematic Review

Background: Diabetes mellitus is a hereditary and degenerative disease that requires management throughout the patient's life to maintain blood sugar stability and psychosocial factors. Aims: This systematic review aims to determine the effect of self-management on the quality of life of patients with Type 2 DM. Methods: The selection of the studies refers to Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) guidelines and JBI's checklist was used to assess the quality of the study. The study selection came from 7 databases Scopus, ScienceDirect, Sage Journals, ProQuest, Emerald Insight, Pubmed dan Taylor & Francis. The number of studies included in the review was 7 articles, 5 articles used an RCT design, and 2 articles were quasi-experimental. Results: The finding showed 2 articles that provide interventions in the form of DSME, 1 article emphasizes self-management interventions based on self-efficacy theory that is oriented towards active family involvement, 1 article specifies interprofessional-based DSM through telemonitoring media, 1 article focuses on community-based self-management interventions, and 1 article specializes in the use of weblogs in conducting self-management. Special 2 articles emphasize nurse leadership in managing interventions during the study. Five articles showed a significant effect of self-management on quality of life and 2 articles had no effect. Conclusion: The findings can be used to optimize self-management intervention in DM patients to improve their quality of life.

Designing and performance analysis of 7 T CNTFET based novel SRAM cell for IoT application

The selection of the title includes designing of SRAM cell using CNTFET because CNTFET overcomes all the issues coming from CMOS technology beyond the 10nm technology node. With the reduction in channel length, the threshold voltage required for CMOS-based technology increases, and the corresponding off-state current decreases. This can prove to be a significant advancement for the semiconductor industry. With the evolution of the new generation of the technology era, especially beyond 10 nm, CMOS is not able to fulfil all the required conditions, as beyond 10 nm technology node, threshold voltage decreases, and consequently off-state current and leakage power increase. This is the reason that CNTFET can be considered a prominent replacement of CMOS transistor for the designing of SRAM cells with the technology node beyond 10 nm. This designed SRAM cell is applicable for IoT applications because IoT uses a microcontroller and the SRAM cell is used as a data memory in the microcontroller. A Data memory always requires high speed, ultra-low power dissipation, and high stability from the cell. Thus, to fulfil this requirement, performance analysis to identify the problem statement of conventional cells and then to improve their performance based on the findings is essential. This is the reason that the 7 T CNTFET-based SRAM novel cell is introduced, and its performance is going to be further improved so that the designed novel cell becomes compatible with IoT applications. Leakage power and stability factor are the main performance parameters to improve of SRAM cells.

Crystallinity as a factor of SERS stability of silver nanoparticles formed by Ar+ irradiation

The plasmonic sensors based on silver nanoparticles are limited in application due to their relatively fast degradation in the ambient atmosphere. The technology of ion-beam modification for the creation of monocrystalline silver nanoparticles (NPs) with stable plasmonic properties will expand the application of silver nanostructures. In the present study, highly-stable monocrystalline NPs were formed on the basis of a thin silver film by low-energy ion irradiation. Combined with lithography, this technique allows the creation of nanoparticle ensembles in variant forms. The characterization of the nanoparticles formed by ion-beam modification showed long-term outstanding for Ag nanoparticles stability of their plasmonic properties due to their monocrystalline structure. According to optical spectroscopy data, the reliable plasmonic properties in the ambient atmosphere are preserved for up to 39 days. The mapping of crystal violet dye via surface-enhanced Raman spectroscopy (SERS) revealed a strong amplification factor sustaining at least thrice as long as the one of similarly sized polycrystalline silver NPs formed by annealing. The plasmonic properties sustain more than a month of storage in the ambient atmosphere. Thus, ion-beam modification of silver film makes it possible to fabricate NPs with stable plasmonic properties and form clusters of NPs for sensor technology and SERS applications.

Changes that stick

Many education leaders may wonder how to implement sustainable policy changes that will benefit youth, families, and the community. Arielle Lentz, Laura Desimone, Amy Stornaiuolo, Katie Pak, Nelson Flores, Philip Nichols, Morgan Polikoff, and Andy Porter share findings from school change efforts in more than 170 districts in five states. They present six key strategies based on this work, and they share examples of how districts employed the success factors of specificity, consistency, power, and stability to help build authority, which in turn led to successful implementation of new policies, curriculums, and professional learnings.

Modulation of Aggregation and Immunogenicity of a Protein: Based on the Study of Hen Lysozyme

This study focuses on the modulation of protein aggregation and immunogenicity. As a starting point for investigating long-range interactions within a non-native protein, the effects of perturbing denatured protein states on their aggregation, including the formation of amyloid fibrils, were evaluated. The effects of adducts, sugar modifications, and stabilization on protein aggregation were then examined. We also investigated how protein immunogenicity was affected by enhancing protein conformational stability and other factors.

The Effect of Emergency Monetary Policy on Liquidity and Financial System Stability in Property Sector Companies in Indonesia

Through a quantitative study utilizing Structural Equation Modeling with Partial Least Squares (SEM-PLS), this research examines the impact of emergency monetary policies on liquidity and financial system stability within Indonesian property sector enterprises. The study takes into account company size, regional distribution, and financial performance by using a broad sample of property sector firms. The validity and reliability of indicators for liquidity, financial system stability, and emergency monetary policies are guaranteed by the measurement model analysis. Contrary to popular belief, the structural model shows that emergency monetary actions have a substantial negative influence on liquidity levels. Complexity can be seen in the relationship between financial system stability and certain policy factors, which can have both positive and negative effects. The robustness of the model is verified by cross-validation and bootstrapping. The results provide sophisticated perspectives to the body of literature by highlighting the necessity of customized methods for formulating policies and devising action plans in the real estate industry amid financial downturns.

LRRC59 promotes the progression of oral squamous cell carcinoma by interacting with SRP pathway components and enhancing the secretion of CKAP4-containing exosomes

BackgroundAs a ribosome receptor, LRRC59 was thought to regulate mRNA translation on the ER membrane. Evidence suggests that LRRC59 is overexpressed in a number of human malignancies and is associated with poor prognoses, but its primary biological function in the development of oral squamous cell carcinoma (OSCC) remains obscure. ObjectiveThe purpose of this study is to investigate at the expression changes and functional role of LRRC59 in OSCC. MethodsLRRC59 gene expression and correlation with prognosis of OSCC patients were first examined using the data from The Cancer Genome Atlas (TCGA) databases. Following that, a series of functional experiments, including cell counting kit-8, cell cycle analysis, wound healing assays, and transwell assays, were carried out to analyze the biological roles of LRRC59 in tumor cells. Mechanistically, we employed Tandem Affinity Purification-Mass Spectrometry (TAP-MS) approach to isolate and identify protein complexes of LRRC59. Downstream regulatory proteins of LRRC59 were verified through immunoprecipitation and immunofluorescence experiments. Furthermore, we isolated exosomes from OSCC cell supernatant and conducted co-culture experiments to examine the effect of LRRC59 knockdown on OSCC cells. ResultsIn samples from OSCC patients, LRRC59 was highly expressed and correlated with poor prognoses. Moreover, the gene sets analysis based on TCGA RNA-seq data indicated that LRRC59 seemed to be strongly related with protein secretory and OSCC migration. Upregulated levels of LRRC59 are more prone to lymph node metastasis in OSCC patients. LRRC59 knockdown impaired the ability of OSCC cell proliferation, migration, and invasion invitro. Mechanistically, our TAP-MS data situate LRRC59 in a functional nexus for mRNA translation regulation via interactions with SRP pathway components, translational initiation factors, CRD-mediated mRNA stabilization factors. More importantly, we found that LRRC59 interacted with cytoskeleton-associated protein 4 (CKAP4) and promoted the formation of CKAP4-containing exosomes. We also revealed that the LRRC59-CKAP4 axis was a crucial regulator of CKAP4-containing exosome secretion in OSCC cells for migration and invasion. ConclusionsTherefore, based on our findings, LRRC59 may serve as a potential biomarker for OSCC patients, and LRRC59-induced exosome secretion via the CKAP4 axis may serve as a potential therapeutic target for OSCC.

Are trunk stability and endurance determinant factors for whole-body dynamic balance in physically active young males? A multidimensional analysis.

Determine if (a) a better trunk stability and endurance are associated with an improved whole-body dynamic balance, and if (b) the assessment tests can be interchanged within each capability. Sixty-three physically active young males performed three trunk stability (i.e., the lumbopelvic stability, the unstable sitting and the sudden loading sitting tests), three trunk muscle endurance (i.e., the Biering-Sørensen, the side bridge and the front bridge tests) and four whole-body dynamic balance (i.e., the tandem and the single-leg stance, the Y-Balance, and the single-leg triple hop tests) tests two times. After assessing the reliability of the variables, a Pearson correlation analysis was performed. The correlations between trunk stability and endurance tests with dynamic balance tests were non-significant except for the unstable sitting test with both the tandem (r = 0.502) and the single-leg stance (r = 0.522) tests. Moreover, no relationships were observed between the trunk stability and the trunk muscle endurance tests. Interestingly, no relationships were found between most tests within each capability (i.e., trunk stability, trunk endurance, and dynamic balance) except: (i) the front bridge stability test and the back (r = 0.461) and the side (r = 0.499) bridge stability tests; (ii) the two side bridge endurance tests (r = 0.786); (iii) the tandem and the single-leg stance tests (0.439 ≤ r ≤ 0.463); (iv) the Y-Balance and the single-leg triple hop tests (0.446 ≤ r ≤ 0.477). Better trunk function does not seem to be a relevant factor for dynamic balance in young active males. In this population, specific measures are needed as the test interchangeability is questioned.

Numerical Investigation of the Interaction of a Circumferential Groove Casing Treatment and Near-Tip Modifications for a Highly Loaded Low-Speed Rotor Under the Influence of Double Leakage

Abstract Eckel et al. (2023, “Numerical Investigation of Near-Tip Modifications for a Highly Loaded Low-Speed Rotor Under the Influence of Double Leakage,” ASME J. Turbomach., 145(4), p. 041003) proposed using a convex-profiled pressure side region close to the tip, known as belly, as an effective method of extending the operating range of low-speed axial compressor rotors. In the literature, circumferential grooves are another well-described technique for improving the stable working range of a compressor rotor. No research has been conducted to date to determine which modification is more effective and how they interact when used together. This paper numerically investigates the influence of circumferential casing grooves and near-tip modifications on the flow field in the tip region of a highly loaded, low-speed axial compressor rotor. The simulated rotor consists of a hybrid blade configuration with a tandem profile in the mid-span region and single blade profiles near the endwalls. The single blade profile close to the tip features three different convex-profiled elements, which differ in their respective thicknesses. The aim of the numerical analysis is to explain the interaction of the secondary flow phenomena when applying the circumferential grooves and the belly geometries. For this purpose, eight different axial positions of the circumferential groove are investigated for each of the three belly configurations. These are arranged in 10% increments from −7% to 63% along the axial rotor tip chord. The potential of the concept is evaluated by a numerical investigation in the 1.5-stage setup with an inlet guide vane and tandem stator. It is shown that a circumferential groove can further increase the operating range for all belly configurations when positioned axially correctly. In this respect, equalization of the near-casing deceleration in the circumferential direction leads to an extension of the stall margin with both modifications. Concentrated regions of low-momentum fluid with a large extent in the radial direction should be avoided consequently. A tip vortex stability factor is introduced to quantitatively evaluate this effect. The operating range can thus already be estimated in a first approximation at the design point. In general, the groove and belly should be positioned where the tip leakage vortex meets the pressure side of the adjacent blade. If the groove is used together with the belly, the leading edge of the former should be situated at the location of maximum thickness of the near-tip modification. The effects of the circumferential groove and the belly are then superimposed. If using only one modification, the belly appears better suited for ensuring an extension of the operating range while maintaining high efficiencies.