The Impact of Volute Versus Collector on Centrifugal Compressor Performance

2002 ◽  
Author(s):  
Y. I. Biba
Keyword(s):  
3D Model ◽  
Internal Flow ◽  
Performance Measurements ◽  
Cross Sectional ◽  
Flow Rates ◽  
Computational Fluid Dynamics Cfd ◽  
Compressor Performance ◽  
The Subject ◽  
Cfd Analyses ◽  
The Impact

As part of a revamp or rerate study, an investigation was undertaken to assess the impact of a collector design versus a volute on compressor performance. The subject compressor was a single stage, axial inlet configuration with a discharge collector rather than the more commonly used scroll volute. The primary distinction between the collector and volute is that the collector cross sectional area is constant at all circumferential locations. A complex 3D model containing the inlet, impeller, low solidity diffuser (LSD), and collector was built. A similar model was also created where the volute was substituted for the collector. Computational Fluid Dynamics (CFD) analyses were performed using these models with results generated at different flow rates. Computational results are presented and compared to test data for collector configuration. The test included standard performance measurements as well as more detailed internal flow data, allowing a credible comparison with the CFD results. Conclusions are drawn with respect to potential compromises in choosing a collector versus a volute.

Prediction of Particle Impact on an Archimedes Screw Runner Blade for Micro Hydro Turbine

2013 ◽  
Vol 465-466 ◽  
pp. 552-556
Author(s):  
Muhammad Ammar Nik Mutasim ◽  
Nurul Suraya Azahari ◽  
Ahmad Alif Ahmad Adam
Keyword(s):  
Three Dimensional ◽  
Leading Edge ◽  
Navier Stokes ◽  
Particle Impact ◽  
Three Dimensional Flow ◽  
Navier Stokes Equation ◽  
Runner Blade ◽  
Computational Fluid Dynamics Cfd ◽  
The Subject ◽  
The Impact

Energy is one of the most important sources in the world especially for developing countries. The subject study is conducted to predict the behaviour of particle due to errosion from the river through the achimedes screw runner and predict the impact of particle toward blade surface. For this reason, computational fluid dynamics (CFD) methods are used. The three-dimensional flow of fluid is numerically analyzed using the Navier-Stokes equation with standard k-ε turbulence model. The reinverse design of archimedes screw blade was refered with the previous researcher. Flow prediction with numerical results such as velocity streamlines, flow pattern and pressure contour for flow of water entering the blade are discussed. This study shows that the prediction of particle impact occurs mostly on the entering surface blade and along the leading edge of the screw runner. Any modification on the design of the screw runner blade can be analyze for further study.

scholarly journals ANALISA FAKTOR RISIKO PEKERJAAN YANG BERPENGARUH TERHADAP KEJADIAN KATARAK PADA MASYARAKAT DI SRAGEN

2017 ◽  
Vol 8 (2) ◽  
Author(s):  
Sri Suparti ◽  
Sri Purwanti
Keyword(s):  
Diabetes Mellitus ◽  
Risk Factor ◽  
Chronic Exposure ◽  
Ultraviolet Rays ◽  
Experience Design ◽  
Cross Sectional ◽  
The Subject ◽  
Cross Sectional Design ◽  
The Impact ◽  
Diabetes Melitus

Katarak merupakan kelainan  lensa mata yang keruh di dalam bola mata. Kekeruhan lensa atau katarak akan mengakibatkan sinar terhalang masuk ke dalam mata sehingga penglihatan menjadi menurun. Banyak faktor dikaitkan dengan katarak, yaitu usia sebagai faktor utama, dan faktor lain seperti penyakit diabetes melitus (DM), pajanan kronis terhadap sinar ultraviolet (sinar matahari), konsumsi alkohol, merokok, tingkat pendidikan, dan pekerjaan. Desain penelitian yang digunakan adalah desain cross sectional subyek penelitian diobservasi hanya satu kali saja dan faktor risiko serta dampak diukur menurut keadaan atau status pada saat observasi. Penelitian ini dilaksanakan untuk mengetahui risiko pekerjaan.Hasil: faktor pekerjaan yang terbukti sebagai faktor risiko terjadinya katarak adalah Satus gizi (p = 0.033; OR adjusted 2.568; 95% CI = 0.962-6851) Umur tua akan berisiko terjadi katarak dengan nilai (p = 0.05 OR adjusted; OR 0.441; 95% CI = 0.962-6851) Kebiasaan merokok (p = 0.001; OR adjusted 5.182 ;95% CI = 1846-14545) Kadar gula darah dalam  tubuh yang lebih dari dua ratus yeng mengalami DM berisiko terjadi katarak dengan nilai (p = 0.000 OR adjusted OR 0.588; 95% CI = 0.740-4.053) Pekerjaan (p = 0.040; OR adjusted OR 5.902 ;95% CI = 0.740-4.053)Simpulan: Umur yang lebih dari empat puluh tahun berisiko 0.441 kali untuk terjadi katarak. Kebiasaan merokok akan berisiko 5.182 kali terjadi katarak. Kadar gula darah yang tinggi lebih dari dua ratus berisiko 0.588 kali terjadi katarak.  Pekerjaan yang terpapar sinar UV secara langsung akan berisiko 5.902 kali terjadi katarak.Kata Kunci: Katarak, Pekerjaan, Faktor Risiko Cataract is an abnormality of eye's lens.Cloudly lens or cataract Will block the ray to the eye so the vision decreases.Many risk factors of cataract these are:Age(the main of risk factor),and other factors are diabetes mellitus(DM),chronic exposure to ultraviolet rays,alchohol,smoking,education,working. Experience design was used cross sectional design and the subject was observed once in experience,risk factor and also the impact measured according to the situations and statues of the observation.this experience did to know the risk factor in work. The result:Risk of work already proven risk to be cataract,statues of nutritions (p:0,033;OR adjusted 2,568;95%,CI:0,962-6851),old age would risk to be cataract with value(p:0,05,OR adjusted;0,441;95%,CI:0,962-6851), habitually of smoking (p:0,001;OR adjusted:5,182;95%CI:1846-14545).glucose in blood more than two hundred of DM risk to be cataract with value p:0,000,OR adjusted 0,588,95%CI:0,740-4,053,working (p:0,040;OR adjusted OR 5,902;95%,CI :0,740-4053).The conclusion:Age more fourty risk 0,441x to be cataract. Habitually of smoking riks 5,182x,glucose in blood more than two hundred risk 0,588x to be cataract,working with UV exposured risk 5,902x to be cataract.Keywords:cataract,working,risk factor.

Effect of Flow Rates on Operation of a Solar Thermochemical Reactor for Splitting CO2 Via the Isothermal Ceria Redox Cycle

2015 ◽  
Vol 138 (1) ◽  
Author(s):  
Brandon J. Hathaway ◽  
Rohini Bala Chandran ◽  
Stephen Sedler ◽  
Daniel Thomas ◽  
Adam Gladen ◽  
...  
Keyword(s):  
Heat Recovery ◽  
Gas Flow ◽  
Gas Flows ◽  
Energy Costs ◽  
Redox Cycle ◽  
External Energy ◽  
Flow Rates ◽  
Computational Fluid Dynamics Cfd ◽  
Solar Thermochemical ◽  
The Impact

A prototype 4 kW solar thermochemical reactor for the continuous splitting of carbon dioxide via the isothermal ceria redox cycle is demonstrated. These first tests of the new reactor showcase both the innovation of continuous on-sun fuel production in a single reactor and remarkably effective heat recovery of the sensible heat of the reactant and product gases. The impact of selection of gas flow rates is explored with respect to reactor fuel productivity and external energy costs of gas separation and pumping. Thermal impacts of gas flow selection are explored by coupling measured temperatures with a computational fluid dynamics (CFD) model to calculate internal temperature distributions and estimate heat recovery. Optimized gas flows selected for operation provide a 75% increase in fuel productivity and reduction in parasitic energy costs by 10% with respect to the design case.

scholarly journals De utryghedsmæssige konsekvenser af udsathed for kriminalitet i Danmark

2020 ◽  
Vol 107 (1) ◽  
pp. 41-66
Author(s):  
Rune H. Scherg ◽  
Anders Ejrnæs
Keyword(s):  
Statistical Models ◽  
Statistical Power ◽  
Demographic Characteristics ◽  
Causal Inferences ◽  
Cross Sectional ◽  
Current Article ◽  
The Subject ◽  
Cross Sectional Studies ◽  
The Impact ◽  
Do So

AbstractThis article examines the consequences of victimisation in relation to feeling of safety in Denmark.2 Using various statistical models, we address two general questions: First, how do different victimisation patterns affect victims’ feelings of safety, and second, how do victims’ demographic characteristics modify the consequences of victimisation in relation to feelings of safety. We analyse panel data from the Danish Police’s Safety Survey (2014-2018) linked to Danish register data. Although there is an abundance of international research about the victimfear nexus, there are still gaps in our current understanding of this relationship. First, research on the impact of victimization on feelings of safety is often based on cross-sectional studies, which don’t allow for solid causal inferences. Second, potential differences between different groups of victims have not been thoroughly analysed as few studies have had the statistical power to do so. Last, there is a scarcity of Scandinavian studies on the subject. The current article shows that victimization has a consistent effect on feelings of safety. However, the size of the effect is generally moderate and short-lived. The article also demonstrates that the impacts of victimization are disproportionately distributed across different groups of victims.

scholarly journals Investigation of Suction Flow Control on Centrifugal Compressor with Vaned Diffuser

Energies ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 583
Author(s):  
Suleyman Emre Ak ◽  
Sertac Cadirci
Keyword(s):  
Flow Control ◽  
Flow Rate ◽  
Centrifugal Compressor ◽  
Pressure Ratio ◽  
Vaned Diffuser ◽  
Flow Rates ◽  
Performance Improvements ◽  
Computational Fluid Dynamics Cfd ◽  
Cfd Analyses ◽  
Suction Flow

In this study, the effect of suction flow control on a centrifugal compressor at operation and stall flow rates was investigated using computational fluid dynamics (CFD). The compressor geometry was reconstructed from available open source profile data and the CFD analyses have been performed on this geometry using the appropriate mesh. To validate the CFD results, the compressor performance line was acquired and compared with the experimental results obtained at the design rotational speed. Then, suction flow control was employed at various suction slot positions with different suction flow rates to improve the performance of the compressor at operation and stall flow rates. As a result of the suction flow control trials, 0.85% increase in pressure ratio and 0.8% increase in adiabatic efficiency were achieved while the compressor was running at operation flow rate. The performance improvements corresponding to the stall flow rate of the compressor were 2.5% increase in pressure ratio and 2% increase in adiabatic efficiency.

scholarly journals Understanding the Effectiveness of a Peer Coach Model in Research-intensive Undergraduate Courses

2019 ◽  
Vol 2 (2) ◽  
pp. 42-56
Author(s):  
Michael Joseph Rovito ◽  
Amanda Koontz ◽  
Martha Garcia ◽  
Mary Tripp ◽  
Kim Schneider ◽  
...  
Keyword(s):  
Undergraduate Students ◽  
Research Process ◽  
Exploratory Research ◽  
Previous Knowledge ◽  
Cross Sectional ◽  
Research Experiences ◽  
The Subject ◽  
Cross Sectional Design ◽  
Peer Coach ◽  
The Impact

The impact of peer coaches embedded in classrooms are outlined in the literature. There is, however, a lack of evidence on when their services should be introduced into the curriculum to have the most impact possible. The goals of this exploratory research project, therefore, were to aim to provide baseline evidence on the most effective and efficient application of ‘Research Coaches’. A total of 129 undergraduate students took part in a cross-sectional design by completing a series of original surveys on the research process and qualities about their research identity. Our research suggests that peer coaches can most benefit those with the least previous research experiences as related to perceived increases in understanding of fields, research skills, previous knowledge of the subject of study and confidence in research abilities. Such quantitative findings are reinforced through our qualitative findings, suggesting that overall, peer coaches and faculty can be perceived as complimentary support systems for effective research-focused course implementation. Future implications of the use of ‘Research Coaches’ in the classroom are discussed.

scholarly journals Personalized Tests in Paralympic Athletes: Aerobic and Anaerobic Performance Profile of Elite Wheelchair Rugby Players

2020 ◽  
Vol 10 (3) ◽  
pp. 118
Author(s):  
Giuseppe Marcolin ◽  
Nicola Petrone ◽  
Michael Benazzato ◽  
Francesco Bettella ◽  
Angela Gottardi ◽  
...  
Keyword(s):  
Cross Sectional Study ◽  
Sport Performance ◽  
Performance Parameters ◽  
Performance Measurements ◽  
Cross Sectional ◽  
Wheelchair Rugby ◽  
Present Cross Sectional Study ◽  
The Impact ◽  
Ranking Analysis ◽  
Aerobic And Anaerobic

In Paralympic sports, the goal of functional classifications is to minimize the impact of impairment on the outcome of the competition. The present cross-sectional study aimed to investigate aerobic and anaerobic personalized tests in Paralympic athletes and to correlate them with the classification of the international wheelchair rugby federation (IWRF). Sixteen elite players of the Italian wheelchair rugby team volunteered for the study. Aerobic (incremental test to exhaustion) and anaerobic (Wingate 30s all-out test, 5 and 10-meter sprint test, shuttle test, isometric test) sport-performance measurements were correlated singularly or grouped (Z scores) with the classification point. Moreover, a multivariate permutation-based ranking analysis investigated possible differences in the overall level of performance among the adjacent classified groups of players, considering the scores of each test. A statistically significant correlation between the performance parameters and the IWRF functional classification considering both aerobic and anaerobic personalized tests was detected (0.58 ≤ r ≤ 0.88; 0.0260 ≤ p ≤ 0.0001). The multivariate permutation-based ranking analysis showed differences only for the low-pointers versus mid-pointers (p = 0.0195) and high-pointers (p = 0.0075). Although single performance parameters correlated with athletes’ classification point, results of the multivariate permutation-based ranking analysis seem to suggest considering only the most significant anaerobic and sport-specific performance parameters among athletes. These should be combined with the physical assessment and the qualitative observation, which are already part of the classification process to improve its effectiveness.

Multidisciplinary team decision is rare and decreasing in percutaneous vascular interventions despite positive impact on in-hospital outcomes

VASA ◽  
2019 ◽  
Vol 48 (3) ◽  
pp. 262-269 ◽  
Author(s):  
Christian-Alexander Behrendt ◽  
Tilo Kölbel ◽  
Thea Schwaneberg ◽  
Holger Diener ◽  
Ralf Hohnhold ◽  
...  
Keyword(s):  
Multidisciplinary Team ◽  
Positive Impact ◽  
Cross Sectional Study ◽  
Invasive Treatment ◽  
Cross Sectional ◽  
Hospital Outcomes ◽  
Vascular Intervention ◽  
Medical Specialties ◽  
Team Decision ◽  
The Impact

Abstract. Background: Worldwide prevalence of peripheral artery disease (PAD) is increasing and peripheral vascular intervention (PVI) has become the primary invasive treatment. There is evidence that multidisciplinary team decision-making (MTD) has an impact on in-hospital outcomes. This study aims to depict practice patterns and time changes regarding MTD of different medical specialties. Methods: This is a retrospective cross-sectional study design. 20,748 invasive, percutaneous PVI of PAD conducted in the metropolitan area of Hamburg (Germany) were consecutively collected between January 2004 and December 2014. Results: MTD prior to PVI was associated with lower odds of early unsuccessful termination of the procedures (Odds Ratio 0.662, p < 0.001). The proportion of MTD decreased over the study period (30.9 % until 2009 vs. 16.6 % from 2010, p < 0.001) while rates of critical limb-threatening ischemia (34.5 % vs. 42.1 %), patients´ age (70 vs. 72 years), PVI below-the-knee (BTK) (13.2 % vs. 22.4 %), and rates of severe TASC C/D lesions BTK (43.2 % vs. 54.2 %) increased (all p < 0.001). Utilization of MTD was different between medical specialties with lowest frequency in procedures performed by internists when compared to other medical specialties (7.1 % vs. 25.7 %, p < 0.001). Conclusions: MTD prior to PVI is associated with technical success of the procedure. Nonetheless, rates of MTD prior to PVI are decreasing during the study period. Future studies should address the impact of multidisciplinary vascular teams on long-term outcomes.

Managing Service Quality, Food Quality, Price Fairness and Customer Retention: A Holistic Perspective

2020 ◽  
Vol 2 (1) ◽  
pp. 1-5
Author(s):  
Ammar Ahmed ◽  
Rafat Naseer ◽  
Muhammad Asadullah ◽  
Hadia Khan
Keyword(s):  
Service Quality ◽  
Food Quality ◽  
Service Sector ◽  
Customer Retention ◽  
Price Fairness ◽  
Policy Makers ◽  
Restaurant Management ◽  
The Subject ◽  
Research Propositions ◽  
The Impact

In this competitive environment, organizations strive to satisfy their customer by providing best quality service at affordable and fair prices with a view to enhance their revenues. To achieve the objective of revenue maximization, organizations strive to identify the factors that help them in retaining their customers. Drawing from the signalling theory of marketing, the current study proposes a novel conceptual model representing the impact of service quality with food quality and price fairness on customer retention in restaurant sector of Pakistan. The paper underlines an important arena of knowledge for academicians as well as organizational scientists on the subject. On the basis of literature available on the variables understudy, the present study forwards eight research propositions worthy of urgent scholarly attention. The conceptualized model of the present article can also be viewed significant in unleashing further avenues for the restaurant management entities, policy makers and future researchers in the domain of managing in the service sector businesses.

Solow economy model

2019 ◽  
pp. 150-157
Author(s):  
Oleksandr Synenko ◽  
Kateryna Yarema ◽  
Yuliia Bezsmertna
Keyword(s):  
Economic Growth ◽  
Regression Analysis ◽  
Solow Model ◽  
Economy Model ◽  
Accelerated Depreciation ◽  
Basic Parameters ◽  
The Subject ◽  
Investment Process ◽  
The Impact ◽  
Model Algorithm

The subject of the research is the approach to the possibility of using the Solow model to perform the regression analysis on the example of the Ukrainian economy model. The purpose of writing this article is to investigate the notion of regres- sion analysis, Solow’s economy model, algorithm for performing regression analy- sis on the example of Ukraine’s economy model. This model can be adapted for the economy of enterprises. Methodology. The research methodology is system-struc- tural and comparative analyzes (to study the structure of GDP); monograph (when studying methods of regression analysis on the example of the Ukrainian economy); economic analysis (when assessing the impact of factors on Ukraine’s GDP). The scientific novelty consists the features of the use of the Solow model on the ex- ample of Ukrainian economy are determined. An algorithm for calculating the basic parameters of a model using the Excel application package is disclosed. The main recommendations on the development of the national economy and economic growth through the use of macroeconomic instruments are given. Conclusions. The use of the Solow model enables forecasting and analysis. The results obtained re- vealed the problem of low resource return of capital as a resource, along with the means of macroeconomic regulation of the investment process, using which can improve the situation. A special place in these funds belongs to the accelerated depreciation and interest rate policies.

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