scholarly journals Verification of CFD tool for simulation of cavitating flows in hydraulic systems

2017 ◽  
Vol 19 (5) ◽  
pp. 653-665 ◽  
Author(s):  
Agnieszka Niedźwiedzka ◽  
Seweryn Lipiński ◽  
Sebastian Kornet
Keyword(s):  
Statistical Analysis ◽  
Volume Fraction ◽  
Correlation Coefficients ◽  
Hydraulic Systems ◽  
Computer Methods ◽  
Main Challenge ◽  
Cavitation Intensity ◽  
History Of ◽  
Fluent Software ◽  
Verification Process

Cavitation is an undesirable phenomenon in hydraulic systems, as it causes erosion and noise. The main difficulty in cavitation prediction when using Fluent software is lack of an openly accessible tool for implementation of a freely chosen homogeneous cavitation model. In this paper the main challenge is to make such a tool, user defined function (UDF). The second challenge is to use a qualitative method in the assessment of the results of verification process. Three cavitation models are verified in Fluent 14.5: Singhal et al., Schnerr & Sauer and Zwart et al. The verification is based on the benchmark example from the Cavitation Modeling tutorial. Three methods of the algorithms verification are used: analysis of the convergence history of volume fraction, comparison of vapour volume fractions and statistical analysis of these data. The original achievements are not only the verified codes but also statistical analysis based on the computer methods of image analysis performed using two correlation coefficients: the first based on the cavitation intensity, and the second based on the changes of the cloud shape. The results of the analyses do not give any reasons to reject the UDFs. The appendix contains the analysed codes (available with the online version of this paper).

Uno studio sulle presidenziali americane: l'economia conta?

2012 ◽  
pp. 41-55
Author(s):  
Marco Morini
Keyword(s):  
Statistical Analysis ◽  
Presidential Elections ◽  
Economic Indicators ◽  
Economic Data ◽  
The Real ◽  
Approval Rating ◽  
History Of ◽  
Electoral Behaviour

The economy matters. This is one of the dogmas taught us by those who have studied the history of the American presidential elections. But is this collective perception of the influence of economic data on individual electoral behaviour confirmed by statistical analysis of the history of presidential elections? This study shows that the most commonly used economic indicators are poor predictors of election outcomes, and also that variation in the approval rating of the incumbent president is a variable independent from the real economic data.

Features hormonal status in pregnant women with benign cervical pathology in anamnesis

2017 ◽  
pp. 71-73
Author(s):  
N.Yu. Bysaha ◽  
Keyword(s):  
Statistical Analysis ◽  
Pregnant Women ◽  
Placental Lactogen ◽  
Control Group ◽  
Hormonal Status ◽  
Hormonal Changes ◽  
Fetoplacental Complex ◽  
History Of ◽  
Objective Study ◽  
Stimulation Of

The objective: study of hormonal status in pregnant women with benign cervical pathology (CP) in anamnesis. Patients and methods. Clinical and statistical analysis of the hormonal status of 100 women with a history of benign CP pathology has been performed. According to the revealed symptoms of CP during colposcopic examination, women were divided into two groups: 100 pregnant women, in whom colposcopic and cytologically signs of CP pathology were not detected, were included in the control group; and 100 women who had a pathology of CP, entered the main group. Results. The study examined hormonal relationships in the system mother–placenta–fetus, namely the level of hormones such as estriol, progesterone, human chorionic gonadotropin, placental lactogen. Hormonal changes in pregnant women and contribute to reducing the immunoreactivity unwanted stimulation of existing benign hyperplastic background processes in the cervix. Conclusion. Determining functional state placenta is an important factor in the timely diagnosis of disorders in the functioning of the system mother–placenta–fetus. Key words: hormonal status, placenta, uterine cervix, fetoplacental complex.

scholarly journals Statistical analysis of solid waste composition data: Arithmetic mean, standard deviation and correlation coefficients

2017 ◽  
Vol 69 ◽  
pp. 13-23 ◽  
Author(s):  
Maklawe Essonanawe Edjabou ◽  
Josep Antoni Martín-Fernández ◽  
Charlotte Scheutz ◽  
Thomas Fruergaard Astrup
Keyword(s):  
Statistical Analysis ◽  
Standard Deviation ◽  
Solid Waste ◽  
Correlation Coefficients ◽  
Arithmetic Mean ◽  
Composition Data ◽  
Waste Composition

scholarly journals Repeatability of a Dual-Scheimpflug Placido Disc Corneal Tomographer/Topographer in Eyes with Keratoconus

2020 ◽  
Author(s):  
Anne Poulsen ◽  
Diane Jang ◽  
Mahmood Khan ◽  
Zaina Nabil Al-Mohtaseb ◽  
Michael Chen ◽  
...  
Keyword(s):  
Image Quality ◽  
Spherical Aberration ◽  
Correlation Coefficients ◽  
Quality Metrics ◽  
Corneal Surgery ◽  
Image Quality Metrics ◽  
Interclass Correlation ◽  
Intrastromal Corneal Ring ◽  
History Of ◽  
Image Quality Metric

Purpose: To investigate the repeatability of a combined Dual-Scheimpflug placido disc corneal topographer (Zeimer Galilei G4) with respect to keratometric indices used to monitor progression of keratoconus (KCN). Methods: Patients with KCN were prospectively enrolled. For each eye lacking history of corneal surgery, 5 measurements were taken in succession. Eyes in which 3 or more measurements could be obtained (defined by the device's 4 image quality metrics) were included in the analysis. The repeatability limits (RL) and interclass correlation coefficients (ICC) were calculated for various parameters. Results: 32 eyes from 25 patients met all image quality metrics, and 54 eyes from 38 patients met at least 3/4 criteria (all except the placido image quality metric). RLs for key parameters when 4/4 or 3/4 image quality metrics were met included: 0.37 and 0.77 diopters (D) for steep simulated keratometry, 0.79 and 1.65 D for maximum keratometry, 13.80 and 13.88 degrees for astigmatism axis, 0.64 and 0.56 um for vertical coma magnitude, and 3.76 and 3.84 um for thinnest pachymetry, respectively. The ICCs for all parameters were excellent [above 0.87 except for spherical aberration (0.77)]. Conclusions: The dual-Scheimpflug placido disc corneal topographer is highly repeatable in quantifying parameters used in monitoring KCN. Excellent placido images are difficult to capture in eyes with KCN, but when available, increase the reliability of the measurements. The RLs may be especially helpful in detecting progression in mild KCN when interventions such as corneal cross-linking or intrastromal corneal ring segments are most beneficial.

scholarly journals Friederike Oberdieck. Beitrag zur Kenntniss des Alkoholimus und seiner rationellen Behandlung. —(Arch. f. Psych. Bd. 27. Heft. 2. pg. 579 — 632)

2020 ◽  
Vol V (4) ◽  
pp. 210
Author(s):  
G. Idelson
Keyword(s):  
Statistical Analysis ◽  
History Of

This work presents a statistical analysis of the history of the illness of alcoholics from the Burghlzli insane asylum during the period from 1879 to 1894 (367 mus. And 31 women). The known facts about the consequences of alcoholism are confirmed again in this work.

scholarly journals Uwarunkowania procesu pojednania w Kambodży

2020 ◽  
Vol 14 ◽  
pp. 267-280
Author(s):  
Radosław Zarzecki
Keyword(s):  
Early Stage ◽  
Khmer Rouge ◽  
State Level ◽  
Political Life ◽  
Historical Background ◽  
Difficult Situation ◽  
Main Challenge ◽  
Long Time ◽  
History Of ◽  
Culture Of Silence

Determinants of Reconciliation in Cambodia Forty years after Cambodian genocide the reconciliation is still in early stage. Despite such long time there was almost nothing done, especially in 20th century, to make that process happened. The article discusses the determinants, reasons and factors that had impact on reconciliation. Determinants can be divided into different categories. First of all the socio-historical background. Circumstances in which Khmer Rouge come to power, their revolutionary approach to economy, implemented reforms, use of children, displacements of people and categorization of citizens had great impact on post-1979 Cambodia. Another determinant is a political one. Policy of post-Khmer Rouge Cambodia rulers stunted the reconciliation. There reason of such actions are multidimensional but the most important one is provenance of People’s Republic of Kampuchea leaders. The most important figures in Cambodia politics are ex-Khmer Rouge soldiers, accused by some of taking a part in genocide. What’s even more confusing, the most powerful opposition party in 1980s were perpetrators themselves and their allies. Even after signing Paris Peace Accords in 1991 until early 2000s there was no will to punish Khmer Rouge officials responsible for genocide. The Cambodian culture of silence, the third determinant, only exacerbates a difficult situation. Cambodians rarely speak about atrocities and harsh past because of fear, shame or trauma. Even in school textbooks until 2009 there was almost nothing said about tragic events which happened between 1975 and 1979. History of Democratic Kampuchea still affects the Cambodian society. Despite sentencing few Khmer Rouge officials in 2010s, there’s still lot to be done also on state-level. Reconciliation and coming back to the state of balance is the main challenge for Cambodia in the nearest future, crucially important to social and political life of this nation.

scholarly journals The Influence of Combined Turbulators on the Hydraulic-Thermal Performance and Exergy Efficiency of MWCNT-Cu/Water Nanofluid in a Parabolic Solar Collector: A Numerical Approach

2021 ◽  
Vol 9 ◽  
Author(s):  
Yacine Khetib ◽  
Ammar Melaibari ◽  
Radi Alsulami
Keyword(s):  
Solar Collector ◽  
Volume Fraction ◽  
Numerical Approach ◽  
Exergy Efficiency ◽  
Multiphase Model ◽  
Two Phase ◽  
Simpler Algorithm ◽  
Fluent Software ◽  
Parabolic Geometries ◽  
Volume Method

The present research benefits from the finite volume method in investigating the influence of combined turbulators on the thermal and hydraulic exergy of a parabolic solar collector with two-phase hybrid MWCNT-Cu/water nanofluid. All parabolic geometries are produced using DesignModeler software. Furthermore, FLUENT software, equipped with a SIMPLER algorithm, is applied for analyzing the performance of thermal and hydraulic, and exergy efficiency. The Eulerian–Eulerian multiphase model and k-ε were opted for simulating the two-phase hybrid MWCNT-Cu/water nanofluid and turbulence model in the collector. The research was analyzed in torsion ratios from 1 to 4, Re numbers from 6,000 to 18,000 (turbulent flow), and the nanofluid volume fraction of 3%. The numerical outcomes confirm that the heat transfer and lowest pressure drop are relevant to the Re number of 18,000, nanofluid volume fraction of 3%, and torsion ratio of 4. Furthermore, in all torsion ratios, rising Re numbers and volume fraction lead to more exergy efficiency. The maximum value of 26.32% in the exergy efficiency was obtained at a volume fraction of 3% and a torsion ratio of 3, as the Re number goes from 60,000 to 18,000.

scholarly journals Major and minor head losses in a hydraulic flow circuit: experimental measurements and a Moody’s diagram application

2020 ◽  
Vol 45 (3) ◽  
pp. 47-56
Author(s):  
Aline Amaral Madeira
Keyword(s):  
Friction Factor ◽  
Correlation Coefficients ◽  
Head Loss ◽  
Rapid Expansion ◽  
Experimental Measurements ◽  
Hydraulic Systems ◽  
Local Loss ◽  
Hydraulic Flow ◽  
Head Losses ◽  
Flow Circuit

Domestic and industrial hydraulic drainage networks have gradually become more complicated because of the cities’ rapid expansion. In surcharged hydraulic systems, the head losses may become rather significant, and should not be neglected because could result in several problems. This work presents an investigation about major and minor head losses in a hydraulic flow circuit, simulating the water transport in a drainage network at room temperature (298.15 K) under atmospheric pressure (101,325 Pa). The losses produced by the fluid viscous effect through the one used cast-iron rectilinear pipe (RP-11) and the localized losses generated by two flow appurtenances, one fully open ball valve (BV-1) and one module of forty-four 90º elbows (90E-8) were experimentally measured. Experimental data generated head-loss curves and their well fitted to potential regressions, displaying correlation coefficients (R2) of 0.9792, 0.9924, and 0.9820 for BV-1, 90E-8, and RP-11, respectively. Head loss experimental equations and local loss coefficients through BV-1 and 90E-8 were determined successfully. The Moody’s diagram application proved to be a quite appropriate tool for an approximate estimation of Darcy-Weisbach friction factor. A good approximation between friction factor values obtained via experimental measurements and the Moody’s diagram was observed with mean absolute deviate of 0.0136.

scholarly journals PODE-SE FAZER UM RELATO PLAUSÍVEL DA HISTÓRIA DA ÉTICA? UMA ALTERNATIVA A AFTER VIRTUE DE MACINTYRE

2013 ◽  
Vol 39 (125) ◽  
pp. 345
Author(s):  
Vittorio Hösle
Keyword(s):  
History Of Philosophy ◽  
Alasdair Macintyre ◽  
Intergenerational Justice ◽  
History Of Ethics ◽  
Main Challenge ◽  
History Of ◽  
Slow Progress ◽  
Important Intermediate ◽  
Value Of Nature

O artigo apresenta uma filosofia da história da Ética que é uma alternativa ao famoso relato de Alasdair MacIntyre em After Virtue. Ainda que a querela entre visões moralistas e imoralistas ocorra diversas vezes na história da filosofia, desde os sofistas até Nietzsche, há também um lento progresso em direção ao universalismo, como foi articulado na sua forma mais elaborada por Kant. Abelardo e Tomás de Aquino são interpretados como as figuras intermediárias mais importantes entre Aristóteles e Kant, mas já o Estoicismo prepara ideias básicas kantianas. O principal desafio da Ética em nosso tempo é a expansão do universalismo para uma teoria da justiça intergeneracional e para um explicação do valor da natureza.Abstract: The essay presents a philosophy of the history of ethics that is an alternative to Alasdair MacIntyre’s famous account in After Virtue. While the quarrel between moralist and immoralist views occurs several times in the history of philosophy, from the sophists to Nietzsche, there is also a slow progress toward universalism, as it was articulated in its most elaborate form by Kant. Abelard and Aquinas are interpreted as the most important intermediate figure between Aristotle and Kant, but already Stoicism prepares basic Kantian ideas. The main challenge of the ethics of our time is the expansion of universalism to a theory of intergenerational justice and an account of the value of nature.

Water resource management in ancient Iran with emphasis on technological approaches: a cultural heritage

2013 ◽  
Vol 13 (3) ◽  
pp. 582-589 ◽  
Author(s):  
Gagik Badalians Gholikandi ◽  
Mandana Sadrzadeh ◽  
Shervin Jamshidi ◽  
Morteza Ebrahimi
Keyword(s):  
Resource Management ◽  
Cultural Heritage ◽  
Water Resource ◽  
Water Resource Management ◽  
Hydraulic Systems ◽  
Water Demands ◽  
Wide Range ◽  
History Of ◽  
Engineered Structures ◽  
Water Conveyance

Water is an essential component in the history of Iran. Due to the unfavorable distribution of surface water and the fluctuation of yearly seasonal streams, to fulfill water demands, ancient Iranians have tried to provide a better condition for utilization of water. Accordingly, elegant designs like qanats became an indispensable element of hydraulic systems, while institutional frameworks were innovated to be combined with in water resource management. Evidence shows that hydraulic structures and water establishments date back thousands of years known as cultural heritage. Besides, the ancient Iranians have realized the importance of an organization to supervise irrigation and water conveyance. Thus, during the Achaemenid and Sasanian Empires, water engineering was developed significantly through the whole territory. The governmental endorsements associated with contemporary engineered structures have made extensive innovations in water systems, such as canals, watermills, water treatment, water storage, piping and construction. The infrastructure fulfilled a wide range of necessities of a civilized country and assisted in achieving its golden era. Consequently, this paper is aimed at studying ancient water resource management and technological approaches in Iran.

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