The Sensitivity Study of a Mechanical Loss Model in Turbocharger System

2020 ◽  
Author(s):  
Haizhu Wang ◽  
Richard Burke ◽  
Colin Copeland
Keyword(s):  
Gasoline Engine ◽  
Critical Role ◽  
Sensitivity Study ◽  
3D Modelling ◽  
Mechanical Loss ◽  
Turbine Efficiency ◽  
Shaft Torque ◽  
The Impact ◽  
Loss Estimate ◽  
Critical Aspects

Abstract 3D modelling can be a very useful tool for optimising the design of turbocharger turbines. However, it is difficult to achieve high levels of correlation with experimental data which can undermine confidence in the 3D model results. A key difference between modelling and experiments is the way turbine efficiency is estimated: in CFD this is estimated directly from the shaft torque created by the turbine, however in experiments this is usually estimated based on the enthalpy rise measured at the compressor. This means that there is an inherent offset between the two which is the mechanical losses of the bearing system used to support the connecting shaft. The accuracy of the mechanical loss estimate can therefore play a critical role in the correlation of 3D modelling with experiments. A 3D CFD model of a turbocharger turbine of a 1.5L gasoline engine has been coupled with a 0D mechanical losses model. The model comprises of seven parameters that characterise the bearing losses such as oil film thickness, bearing surface finish and clearances. A sensitivity study is conducted on these parameters to understand which are the critical aspects that should be parameterised and what relationship these parameters may have with the operating state of the turbocharger (shaft speed, shaft torque etc.). Experimental measurements were conducted for the same turbocharger to provide a baseline for assessing the impact of the mechanical losses model. These provide the boundary conditions to the CFD by ignoring the effects of heat transfer, and the results were compared to the 3D simulation results.

The Laryngeal Epithelium in Reflux

2011 ◽  
Vol 21 (3) ◽  
pp. 112-117 ◽  
Author(s):  
Elizabeth Erickson-Levendoski ◽  
Mahalakshmi Sivasankar
Keyword(s):  
Laryngopharyngeal Reflux ◽  
Critical Role ◽  
Structure And Function ◽  
Laryngeal Disease ◽  
Health And Disease ◽  
And Function ◽  
The Impact

The epithelium plays a critical role in the maintenance of laryngeal health. This is evident in that laryngeal disease may result when the integrity of the epithelium is compromised by insults such as laryngopharyngeal reflux. In this article, we will review the structure and function of the laryngeal epithelium and summarize the impact of laryngopharyngeal reflux on the epithelium. Research investigating the ramifications of reflux on the epithelium has improved our understanding of laryngeal disease associated with laryngopharyngeal reflux. It further highlights the need for continued research on the laryngeal epithelium in health and disease.

AFRICA’S RENAISSANCE AND POTENTIAL IN THE LEATHER SECTOR WITH REFLECTION TO THE GLOBAL PERFORMANCE

2015 ◽  
Vol 2 (1) ◽  
pp. 1-17 ◽  
Author(s):  
Mwinyihija M.
Keyword(s):  
Value Chain ◽  
Small And Medium Enterprises ◽  
Middle Level ◽  
Individual Member ◽  
Socioeconomic Indicators ◽  
Value Add ◽  
Medium Enterprises ◽  
The Impact ◽  
Productivity And Competitiveness ◽  
Critical Aspects

Africa’s renaissance is inevitable and rapidly emerging as a reality in tandem with the continent’s continued exploration of its natural resources in a more sustained way than previously done. Currently, the clarion call is to value add, avoid plundering and involve its population through the SME’s to adapt modern methods of entrepreneurship. During the study, critical aspects that are envisaged to trigger the growth and development of Africa, included the entry of major countries of the continent into the global emerging markets such as MINT (Mexico, Indonesia, Nigeria and Turkey) and BRICS (Brazil, Russia, India, China and South Africa). For the leather sector, certain socioeconomic indicators such as the youthful participation in the value chain, ownership status, literacy levels and acquired experiences are all contributing to a vibrant sector. It was observed that these indicators if well aligned with individual member states of African Union Commission and structured than productivity and competitiveness of leather products will be attained. As such, ease of either foreign direct investment, local recapitalization and development of the SME’s could become feasible. Indeed, with the emergence of over 300 million youth at middle level income level is construed to start building on the impact of the continents purchasing power. Therefore, Africa needs to respond by address on development of ICT, develop affordable financial support to provide stimulus packages to SME’s (Small and Medium Enterprises) to transform, improve on inter and intra trade to optimize on unexplored synergies and enhance mobility of persons with in Africa as preamble to Africa’s renaissance.

scholarly journals The lung–gut axis during viral respiratory infections: the impact of gut dysbiosis on secondary disease outcomes

2021 ◽  
Author(s):  
Valentin Sencio ◽  
Marina Gomes Machado ◽  
François Trottein
Keyword(s):  
Gut Microbiota ◽  
Bacterial Infections ◽  
Respiratory Infections ◽  
Critical Role ◽  
Good Health ◽  
Disease Outcomes ◽  
And Function ◽  
Viral Respiratory Infections ◽  
The Impact ◽  
Viral Respiratory

AbstractBacteria that colonize the human gastrointestinal tract are essential for good health. The gut microbiota has a critical role in pulmonary immunity and host’s defense against viral respiratory infections. The gut microbiota’s composition and function can be profoundly affected in many disease settings, including acute infections, and these changes can aggravate the severity of the disease. Here, we discuss mechanisms by which the gut microbiota arms the lung to control viral respiratory infections. We summarize the impact of viral respiratory infections on the gut microbiota and discuss the potential mechanisms leading to alterations of gut microbiota’s composition and functions. We also discuss the effects of gut microbial imbalance on disease outcomes, including gastrointestinal disorders and secondary bacterial infections. Lastly, we discuss the potential role of the lung–gut axis in coronavirus disease 2019.

scholarly journals Methionine Diet Evoked Hyperhomocysteinemia Causes Hippocampal Alterations, Metabolomics Plasma Changes and Behavioral Pattern in Wild Type Rats

2021 ◽  
Vol 22 (9) ◽  
pp. 4961
Author(s):  
Maria Kovalska ◽  
Eva Baranovicova ◽  
Dagmar Kalenska ◽  
Anna Tomascova ◽  
Marian Adamkov ◽  
...  
Keyword(s):  
Morphological Changes ◽  
Brain Area ◽  
Critical Role ◽  
Cerebrovascular Diseases ◽  
Behavioral Pattern ◽  
Cell Physiology ◽  
Male Wistar Rats ◽  
High Level ◽  
Hippocampal Alterations ◽  
The Impact

L-methionine, an essential amino acid, plays a critical role in cell physiology. High intake and/or dysregulation in methionine (Met) metabolism results in accumulation of its intermediate(s) or breakdown products in plasma, including homocysteine (Hcy). High level of Hcy in plasma, hyperhomocysteinemia (hHcy), is considered to be an independent risk factor for cerebrovascular diseases, stroke and dementias. To evoke a mild hHcy in adult male Wistar rats we used an enriched Met diet at a dose of 2 g/kg of animal weight/day in duration of 4 weeks. The study contributes to the exploration of the impact of Met enriched diet inducing mild hHcy on nervous tissue by detecting the histo-morphological, metabolomic and behavioural alterations. We found an altered plasma metabolomic profile, modified spatial and learning memory acquisition as well as remarkable histo-morphological changes such as a decrease in neurons’ vitality, alterations in the morphology of neurons in the selective vulnerable hippocampal CA 1 area of animals treated with Met enriched diet. Results of these approaches suggest that the mild hHcy alters plasma metabolome and behavioural and histo-morphological patterns in rats, likely due to the potential Met induced changes in “methylation index” of hippocampal brain area, which eventually aggravates the noxious effect of high methionine intake.

scholarly journals NLRP7 Promotes Choriocarcinoma Growth and Progression through the Establishment of an Immunosuppressive Microenvironment

Cancers ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 2999
Author(s):  
Deborah Reynaud ◽  
Roland Abi Nahed ◽  
Nicolas Lemaitre ◽  
Pierre-Adrien Bolze ◽  
Wael Traboulsi ◽  
...  
Keyword(s):  
Immune Response ◽  
Tumor Cells ◽  
Major Gene ◽  
Critical Role ◽  
Orthotopic Model ◽  
Independent Manner ◽  
Maternal Immune Response ◽  
The Impact

The inflammatory gene NLRP7 is the major gene responsible for recurrent complete hydatidiform moles (CHM), an abnormal pregnancy that can develop into gestational choriocarcinoma (CC). However, the role of NLRP7 in the development and immune tolerance of CC has not been investigated. Three approaches were employed to define the role of NLRP7 in CC development: (i) a clinical study that analyzed human placenta and sera collected from women with normal pregnancies, CHM or CC; (ii) an in vitro study that investigated the impact of NLRP7 knockdown on tumor growth and organization; and (iii) an in vivo study that used two CC mouse models, including an orthotopic model. NLRP7 and circulating inflammatory cytokines were upregulated in tumor cells and in CHM and CC. In tumor cells, NLRP7 functions in an inflammasome-independent manner and promoted their proliferation and 3D organization. Gravid mice placentas injected with CC cells invalidated for NLRP7, exhibited higher maternal immune response, developed smaller tumors, and displayed less metastases. Our data characterized the critical role of NLRP7 in CC and provided evidence of its contribution to the development of an immunosuppressive maternal microenvironment that not only downregulates the maternal immune response but also fosters the growth and progression of CC.

scholarly journals Training may enhance early childhood educators’ self-efficacy to lead physical activity in childcare

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Brianne A. Bruijns ◽  
Andrew M. Johnson ◽  
Jennifer D. Irwin ◽  
Shauna M. Burke ◽  
Molly Driediger ◽  
...  
Keyword(s):  
Physical Activity ◽  
Early Childhood ◽  
Self Efficacy ◽  
Critical Role ◽  
Early Childhood Educators ◽  
Outdoor Play ◽  
Future Research ◽  
Intervention Component ◽  
Space Extension ◽  
The Impact

Abstract Background Early childhood educators (ECEs) play a critical role in promoting physical activity (PA) among preschoolers in childcare; thus, PA-related training for ECEs is essential. The Supporting PA in the Childcare Environment (SPACE) intervention incorporated: 1. shorter, more frequent outdoor play sessions; 2. provision of portable play equipment; and, PA training for ECEs. An extension of the SPACE intervention (the SPACE-Extension) incorporated only the shorter, more frequent outdoor play periods component of the original SPACE intervention. The purpose of this study was to explore the individual impact of these interventions on ECEs’ PA-related self-efficacy and knowledge. Methods ECEs from the SPACE (n = 83) and SPACE-Extension (n = 31) were administered surveys at all intervention time-points to assess: self-efficacy to engage preschoolers in PA (n = 6 items; scale 0 to 100); self-efficacy to implement the intervention (n = 6 items); and, knowledge of preschooler-specific PA and screen-viewing guidelines (n = 2 items). A linear mixed effects model was used to analyze the impact of each intervention on ECEs’ self-efficacy and knowledge and controlled for multiple comparison bias. Results The SPACE intervention significantly impacted ECEs’ self-efficacy to engage preschoolers in PA for 180 min/day (main effect), and when outdoor playtime was not an option (interaction effect). Further, the interaction model for ECEs’ knowledge of the total PA guideline for preschoolers approached significance when compared to the main effects model. Participants within the SPACE-Extension did not demonstrate any significant changes in self-efficacy or knowledge variables. Conclusions Findings from this study highlight the benefit of ECE training in PA with regard to fostering their PA-related self-efficacy and knowledge. Future research should explore the impact of PA training for ECEs uniquely in order to determine if this intervention component, alone, can produce meaningful changes in children’s PA behaviours at childcare.

scholarly journals Arginine Decarboxylase Is Essential for Pneumococcal Stress Responses

Pathogens ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 286
Author(s):  
Mary Frances Nakamya ◽  
Moses B. Ayoola ◽  
Leslie A. Shack ◽  
Mirghani Mohamed ◽  
Edwin Swiatlo ◽  
...  
Keyword(s):  
Stress Responses ◽  
Critical Role ◽  
Acid Stress ◽  
Arginine Decarboxylase ◽  
Arginine Deiminase ◽  
Dependent Manner ◽  
Cellular Processes ◽  
Opportunistic Human Pathogen ◽  
Thiol Peroxidase ◽  
The Impact

Polyamines such as putrescine, cadaverine, and spermidine are small cationic molecules that play significant roles in cellular processes, including bacterial stress responses and host–pathogen interactions. Streptococcus pneumoniae is an opportunistic human pathogen, which causes several diseases that account for significant morbidity and mortality worldwide. As it transits through different host niches, S. pneumoniae is exposed to and must adapt to different types of stress in the host microenvironment. We earlier reported that S. pneumoniae TIGR4, which harbors an isogenic deletion of an arginine decarboxylase (ΔspeA), an enzyme that catalyzes the synthesis of agmatine in the polyamine synthesis pathway, has a reduced capsule. Here, we report the impact of arginine decarboxylase deletion on pneumococcal stress responses. Our results show that ΔspeA is more susceptible to oxidative, nitrosative, and acid stress compared to the wild-type strain. Gene expression analysis by qRT-PCR indicates that thiol peroxidase, a scavenger of reactive oxygen species and aguA from the arginine deiminase system, could be important for peroxide stress responses in a polyamine-dependent manner. Our results also show that speA is essential for endogenous hydrogen peroxide and glutathione production in S. pneumoniae. Taken together, our findings demonstrate the critical role of arginine decarboxylase in pneumococcal stress responses that could impact adaptation and survival in the host.

scholarly journals Mechanosensation and Mechanotransduction by Lymphatic Endothelial Cells Act as Important Regulators of Lymphatic Development and Function

2021 ◽  
Vol 22 (8) ◽  
pp. 3955
Author(s):  
László Bálint ◽  
Zoltán Jakus
Keyword(s):  
Endothelial Cells ◽  
Endothelial Cell ◽  
Cell Fate ◽  
Molecular Mechanisms ◽  
Critical Role ◽  
Mechanical Forces ◽  
Lymphatic Endothelial Cells ◽  
Lymphatic Development ◽  
And Function ◽  
The Impact

Our understanding of the function and development of the lymphatic system is expanding rapidly due to the identification of specific molecular markers and the availability of novel genetic approaches. In connection, it has been demonstrated that mechanical forces contribute to the endothelial cell fate commitment and play a critical role in influencing lymphatic endothelial cell shape and alignment by promoting sprouting, development, maturation of the lymphatic network, and coordinating lymphatic valve morphogenesis and the stabilization of lymphatic valves. However, the mechanosignaling and mechanotransduction pathways involved in these processes are poorly understood. Here, we provide an overview of the impact of mechanical forces on lymphatics and summarize the current understanding of the molecular mechanisms involved in the mechanosensation and mechanotransduction by lymphatic endothelial cells. We also discuss how these mechanosensitive pathways affect endothelial cell fate and regulate lymphatic development and function. A better understanding of these mechanisms may provide a deeper insight into the pathophysiology of various diseases associated with impaired lymphatic function, such as lymphedema and may eventually lead to the discovery of novel therapeutic targets for these conditions.

scholarly journals Modeling Bacterial Regrowth and Trihalomethane Formation in Water Distribution Systems

Water ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 463
Author(s):  
Gopinathan R. Abhijith ◽  
Leonid Kadinski ◽  
Avi Ostfeld
Keyword(s):  
Distribution Systems ◽  
Water Distribution ◽  
Mechanistic Model ◽  
Water Distribution Systems ◽  
Sensitivity Study ◽  
Operating Conditions ◽  
Growth Rate Constant ◽  
Model Parameters ◽  
Bacterial Regrowth ◽  
The Impact

The formation of bacterial regrowth and disinfection by-products is ubiquitous in chlorinated water distribution systems (WDSs) operated with organic loads. A generic, easy-to-use mechanistic model describing the fundamental processes governing the interrelationship between chlorine, total organic carbon (TOC), and bacteria to analyze the spatiotemporal water quality variations in WDSs was developed using EPANET-MSX. The representation of multispecies reactions was simplified to minimize the interdependent model parameters. The physicochemical/biological processes that cannot be experimentally determined were neglected. The effects of source water characteristics and water residence time on controlling bacterial regrowth and Trihalomethane (THM) formation in two well-tested systems under chlorinated and non-chlorinated conditions were analyzed by applying the model. The results established that a 100% increase in the free chlorine concentration and a 50% reduction in the TOC at the source effectuated a 5.87 log scale decrement in the bacteriological activity at the expense of a 60% increase in THM formation. The sensitivity study showed the impact of the operating conditions and the network characteristics in determining parameter sensitivities to model outputs. The maximum specific growth rate constant for bulk phase bacteria was found to be the most sensitive parameter to the predicted bacterial regrowth.

Sign in / Sign up

Export Citation Format

Share Document