The rise heights of low- and high-Froude-number turbulent axisymmetric fountains

2011 ◽  
Vol 691 ◽  
pp. 392-416 ◽  
Author(s):  
H. C. Burridge ◽  
G. R. Hunt
Keyword(s):  
Experimental Investigation ◽  
Main Body ◽  
Quasi Steady State ◽  
Initial Height ◽  
Initial Rise ◽  
Start Up ◽  
High Froude Number ◽  
Set Up ◽  
Rise Height ◽  
Insight Into

AbstractWe present the results of an experimental investigation across a broad range of source Froude numbers,$0. 4\leq {\mathit{Fr}}_{0} \leq 45$, into the dynamics, morphology and rise heights of Boussinesq turbulent axisymmetric fountains in quiescent uniform environments. Typically, these fountains are thought to rise to an initial height,${z}_{i} $, before settling back and fluctuating about a lesser (quasi-) steady height,${z}_{ss} $. Our measurements show that this is not always the case and the ratio of the fountain’s initial rise height to steady rise height,$\lambda = {z}_{i} / {z}_{ss} $, varies widely,$0. 5\lesssim \lambda \lesssim 2$, across the range of${\mathit{Fr}}_{0} $investigated. As a result of near-ideal start-up conditions provided by the experimental set-up we were consistently able to form a vortex at the fountain’s front. This enabled new insights into two features of the initial rise of turbulent fountains. Firstly, for$1. 0\lesssim {\mathit{Fr}}_{0} \lesssim 1. 7$the initial rise height islessthan the steady rise height. Secondly, for${\mathit{Fr}}_{0} \gtrsim 5. 5$, the vortex formed at the fountain’s front pinches off, separates from the main body and rises high above the fountain; there is thus a third rise height to consider, namely, the maximum vortex rise height,${z}_{v} $. From our observations we propose classifying turbulent axisymmetric fountains into five regimes (as opposed to the current three regimes) and present detailed descriptions of the flow in each. Finally, based on an analysis of the rise height fluctuations and the width of fountains in (quasi-) steady state we provide further insight into the physical cause of height fluctuations.

scholarly journals Torsion-shear behaviour at the interfaces of rigid interlocking blocks in masonry assemblages: experimental investigation and analytical approaches

2021 ◽  
Vol 54 (3) ◽  
Author(s):  
Claudia Casapulla ◽  
Elham Mousavian ◽  
Luca Argiento ◽  
Carla Ceraldi ◽  
Katalin Bagi
Keyword(s):  
Experimental Investigation ◽  
Ad Hoc ◽  
Pure Shear ◽  
Shear Capacity ◽  
Shear Behaviour ◽  
Main Body ◽  
Shear Failures ◽  
Set Up ◽  
External Forces ◽  
Analytical Approaches

AbstractIncreasing interest has recently been devoted to interlocking blocks/interfaces capable to enhance the sliding resistance of masonry joints to external forces. In this framework, this paper deals with the assessment of the torsion-shear capacity of the contact interface between the lock and the main body of an interlocking block, assumed to have a cohesive behaviour. The interlocking block is a rigid unit which, on its faces, have square cuboidal locks keeping the adjacent/overlapped blocks together and preventing blocks from sliding. Two numerical approaches and a novel ad hoc experimental investigation are proposed to simulate the torsion-shear behaviour by applying eccentrical shear forces to the lock. First, concave, convex and corrected concave formulations provided by the literature for assemblages of rigid blocks with conventional planar joints are extended to model the interlocking block behaviour. Then, according to a second approach based on the discrete element method, the concave-shaped interlocking block is modelled by convex polyhedrons representing the lock and the main body of the block, considered as individual rigid units stacked over each other with a cohesive contact in between. A novel experimental investigation on the limiting pure shear and torsion-shear combinations at the lock interface made of cohesive material is also presented. Two different mortars were chosen to make the specimens, which were casted using 3D printed moulds, and different test configurations were set up to simulate shear and torsion-shear failures. The analytical and numerical results are compared with each other and against the experimental ones, with interesting remarks on the application of the different approaches.

scholarly journals Experimental Investigation of a Helium-Cooled Breeding Blanket First Wall under LOFA Conditions and Pre-Test and Post-Test Numerical Analysis

2021 ◽  
Vol 11 (24) ◽  
pp. 12010
Author(s):  
Bradut-Eugen Ghidersa ◽  
Bruno Gonfiotti ◽  
André Kunze ◽  
Valentino Di Marcello ◽  
Mihaela Ionescu-Bujor ◽  
...  
Keyword(s):  
Experimental Investigation ◽  
Practical Experience ◽  
First Wall ◽  
Test Analysis ◽  
Fusion Safety ◽  
Post Test ◽  
Fast Transients ◽  
Set Up ◽  
Definition Of ◽  
Insight Into

The experimental investigation of a prototypical set-up simulating a loss of flow accident in a helium-cooled breeding blanket first wall mock-up under typical heat load conditions is presented. The experimental campaign reproduces the expected DEMO thermal-hydraulics conditions during normal and off-normal situations and aims at providing some insight into the fast transients associated with the loss of flow in the blanket first wall. The experimental set-up and the definition of the experimental matrix are discussed, including pre-test analysis performed in support of these activities. The major experimental results are discussed, and a procedure of using the acquired data for validating and calibrating the RELAP-3D model of the mock-up is introduced. All these activities contributed to the creation of a relevant theoretical and practical experience that can be used in further studies concerning incidental transients in real-plant scenarios in the framework of DEMO plant fusion safety activities.

scholarly journals Torsion-shear behaviour at the interfaces of rigid interlocking blocks in masonry assemblages. Experimental investigation and analytical approaches

2021 ◽  
Author(s):  
Claudia Casapulla ◽  
Elham Mousavian ◽  
Luca Argiento ◽  
Carla Ceraldi ◽  
Katalin Bagi
Keyword(s):  
Experimental Investigation ◽  
Ad Hoc ◽  
Pure Shear ◽  
Shear Capacity ◽  
Shear Behaviour ◽  
Main Body ◽  
Shear Failures ◽  
Set Up ◽  
External Forces ◽  
Analytical Approaches

Abstract Increasing interest has recently been devoted to interlocking blocks/interfaces capable to enhance the sliding resistance of masonry joints to external forces. In this framework, this paper deals with the assessment of the torsion-shear capacity of the contact interface between the lock and the main body of an interlocking block, assumed to have a cohesive behaviour. The interlocking block is a rigid unit which, on its faces, have locks keeping the adjacent/overlapped blocks together and preventing blocks from sliding. Two numerical approaches and a novel ad hoc experimental investigation are proposed to simulate the torsion-shear behaviour by applying eccentrical shear forces to the lock. First, concave, convex and corrected concave formulations provided by the literature for assemblages of rigid blocks with conventional planar joints are extended to model the interlocking block behaviour. Then, according to a second approach based on the discrete element method, the concave-shaped interlocking block is modelled by convex polyhedrons representing the lock and the main body of the block, considered as individual rigid units stacked over each other with a cohesive contact in between. A novel experimental investigation on the limiting pure shear and torsion-shear combinations at the lock interface made of cohesive material is also presented. Two different mortars were chosen to make the specimens, which were casted using 3D printed moulds, and different test configurations were set up to simulate shear and torsion-shear failures. The analytical and numerical results are compared with each other and against the experimental ones, with interesting remarks on the application of the different approaches.

Teacher digital competence: bringing education to the next level

2020 ◽  
Vol 11 (1) ◽  
pp. 22-26
Author(s):  
S.V. Tsymbal ◽  
Keyword(s):  
Deep Learning ◽  
Learning Experiences ◽  
Digital Competence ◽  
Digital Revolution ◽  
Access Information ◽  
Set Up ◽  
Insight Into ◽  
The Way

The digital revolution has transformed the way people access information, communicate and learn. It is teachers' responsibility to set up environments and opportunities for deep learning experiences that can uncover and boost learners’ capacities. Twentyfirst century competences can be seen as necessary to navigate contemporary and future life, shaped by technology that changes workplaces and lifestyles. This study explores the concept of digital competence and provide insight into the European Framework for the Digital Competence of Educators.

Reproductive behavior of the blind mole-rat (Spalax ehrenbergi) in a seminatural burrow system

2000 ◽  
Vol 78 (4) ◽  
pp. 570-577 ◽  
Author(s):  
Irit Gazit ◽  
Joseph Terkel
Keyword(s):  
Reproductive Behavior ◽  
Spalax Ehrenbergi ◽  
Mole Rat ◽  
Management Protocol ◽  
In Captivity ◽  
Set Up ◽  
Tunnel System ◽  
Insight Into ◽  
Significant Factors ◽  
Lengthy Process

The blind mole-rat (Spalax ehrenbergi) is a fossorial mammal that is solitary and highly aggressive in nature. The consequent difficulties of maintaining this species in captivity have hindered attempts to gain insight into its behavior and reproductive biology. This article describes an innovative artificial tunnel system and management protocol that facilitated our study of the reproductive behavior of the blind mole-rat in captivity. The study employed a naturalistic approach that allowed the animals to establish separate territories in a seminatural tunnel system and to become familiar with each other over a period of months. This approach contrasts with previous unsuccessful attempts in which mole-rats were introduced without a period of acclimation to each other or to the experimental set-up. The results reveal that both the length of acquaintance between a pair of mole-rats and their own control of the timing of encounters are the most significant factors in reducing aggression and stress. Courtship in blind mole-rats is a lengthy process during which the animals gradually become accustomed to one another, which leads to a reduction of aggression and the initiation of positive "contact movements," eventually enabling copulation to occur. Minimal disturbance by the researcher and initiation of encounters by the mole-rats themselves appear to be the factors that led to a successful mating, pregnancy, and, 34 days later, to the female giving birth and rearing the pups in captivity.

COMPARATIVE EFFECTS OF 3-INDOLYLBUTYRIC ACID, 2,3,5-TRI-IODOBENZOIC ACID, AND β-NAPHTHOXYACETIC ACID ON FLOWER GROWTH AND FLOWER WEIGHT OF THE CAULIFLOWER (BRASSICA OLERACEA)

1959 ◽  
Vol 37 (3) ◽  
pp. 471-478
Author(s):  
B. C. Das
Keyword(s):  
Brassica Oleracea ◽  
Control Group ◽  
Treatment Groups ◽  
Enhanced Production ◽  
Initial Rise ◽  
Flower Growth ◽  
Growth Promoting ◽  
Set Up ◽  
Synthetic Growth ◽  
Iodobenzoic Acid

Three synthetic growth-promoting substances were administered to cauliflower plants (Brassica oleracea) to determine their effect on flower weight and flower growth. A Youden square experimental design was employed to set up treatment groups for all possible combinations of three substances at four concentration levels and three frequencies of application, and an untreated control group. The substances employed were 3-indolylbutyric acid (IBA), 2,3,5-tri-iodobenzoic acid (TIBA), and β-naphthoxyacetic acid (NOXA); concentrations used were 0.01, 0.2, 4.0, and 80.0 parts per million; and frequencies adopted were 2, 3, and 6 times in a 12-day period. Final flower weights were analyzed by an analysis of variance which showed that the treatments differed significantly (P <.01). Treatments with NOXA and IBA produced flowers weighing significantly more than those of the control group. Flower growth was characterized by a rapid initial rise, which subsequently levelled off in the control group. For treated groups, the initial rise continued throughout the flowering period. The results suggest that the use of certain synthetic growth-promoting substances may be feasible commercially for enhanced production of cauliflower crops.

Development of Reliable NARX Models of Gas Turbine Cold, Warm and Hot Start-Up

2017 ◽  
Author(s):  
Hilal Bahlawan ◽  
Mirko Morini ◽  
Michele Pinelli ◽  
Pier Ruggero Spina ◽  
Mauro Venturini
Keyword(s):  
Gas Turbine ◽  
Training Data ◽  
Series Data ◽  
Data Sets ◽  
Control Logic ◽  
Start Up ◽  
Hot Start ◽  
Narx Models ◽  
Set Up ◽  
Rapid Transients

This paper documents the set-up and validation of nonlinear autoregressive exogenous (NARX) models of a heavy-duty single-shaft gas turbine. The considered gas turbine is a General Electric PG 9351FA located in Italy. The data used for model training are time series data sets of several different maneuvers taken experimentally during the start-up procedure and refer to cold, warm and hot start-up. The trained NARX models are used to predict other experimental data sets and comparisons are made among the outputs of the models and the corresponding measured data. Therefore, this paper addresses the challenge of setting up robust and reliable NARX models, by means of a sound selection of training data sets and a sensitivity analysis on the number of neurons. Moreover, a new performance function for the training process is defined to weigh more the most rapid transients. The final aim of this paper is the set-up of a powerful, easy-to-build and very accurate simulation tool which can be used for both control logic tuning and gas turbine diagnostics, characterized by good generalization capability.

XXXVIII.—Observations with a Current Meter in Loch Ness

1909 ◽  
Vol 29 ◽  
pp. 619-647 ◽  
Author(s):  
E. M. Wedderburn ◽  
W. Watson
Keyword(s):  
Experimental Investigation ◽  
Fixed Point ◽  
Great Lakes ◽  
Large Lake ◽  
Deep Lakes ◽  
Small Lake ◽  
Stormy Weather ◽  
Set Up ◽  
A Current ◽  
Made In

One of the authors having made an experimental investigation on the currents produced in a trough of water by a blast of air driven along the surface of the water, it was desired to test the correctness of his deductions by actual observations in a large lake. Loch Ness was chosen on account of its length and uniformity of basin, as it was thought that the length and narrowness of the loch would lead to clearly defined currents being set up in the lake. The sequel showed, as in the case of observations on seiches, that it would have been better to confine attention to a smaller lake, for a twofold reason, (1) because in a large lake the difficulties of observations are much greater than in a small lake during stormy weather, and in very deep lakes the difficulties in the way of obtaining a fixed point from which to use the current meter are formidable, and (2) because it would seem from a few observations made in Loch Garry (Ness Basin) that currents are more defined and more regular in small than in great lakes.

Rapid start-up of one-stage deammonification MBBR without addition of external inoculum

2016 ◽  
Vol 74 (11) ◽  
pp. 2541-2550 ◽  
Author(s):  
Linda Kanders ◽  
Daniel Ling ◽  
Emma Nehrenheim
Keyword(s):  
Wastewater Treatment Plants ◽  
Full Scale ◽  
Anammox Bacteria ◽  
Operational Mode ◽  
Bacterial Populations ◽  
Reject Water ◽  
One Stage ◽  
Start Up ◽  
Laboratory Reactor ◽  
Set Up

In recent years, the anammox process has emerged as a useful method for robust and efficient nitrogen removal in wastewater treatment plants (WWTPs). This paper evaluates a one-stage deammonification (nitritation and anammox) start-up using carrier material without using anammox inoculum. A continuous laboratory-scale process was followed by full-scale operation with reject water from the digesters at Bekkelaget WWTP in Oslo, Norway. A third laboratory reactor was run in operational mode to verify the suitability of reject water from thermophilic digestion for the deammonification process. The two start-ups presented were run with indigenous bacterial populations, intermittent aeration and dilution, to favour growth of the anammox bacterial branches. Evaluation was done by chemical and fluorescence in situ hybridization analyses. The results demonstrate that anammox culture can be set up in a one-stage process only using indigenous anammox bacteria and that a full-scale start-up process can be completed in less than 120 days.

scholarly journals Consolidating the interactive analysis and Grid infrastructure at DESY

2020 ◽  
Vol 245 ◽  
pp. 07003
Author(s):  
Christoph Beyer ◽  
Thomas Finnern ◽  
Martin Flemming ◽  
Andreas Gellrich ◽  
Thomas Hartmann ◽  
...  
Keyword(s):  
Lessons Learned ◽  
Tier 2 ◽  
Interactive Analysis ◽  
Batch Systems ◽  
Batch System ◽  
Start Up ◽  
High Responsiveness ◽  
Primary Focus ◽  
Set Up ◽  
National Analysis

Within WLCG, the DESY site in Hamburg is one of the largest Tier-2 sites with about 18500 CPU cores for Grid workloads. Additionally, about 8000 CPU cores are available for interactive user analyses in the National Analysis Factory [NAF]. After migrating these two batch systems onto a common HTCondor based set-up during the previous four years, we recapitulate the lessons learned during the transition especially since both use cases differ in their workloads. For Grid jobs start-up latencies are negligible and the primary focus is on an optimal utilization of the resources. Complementary, users of the NAF expect a high responsiveness of the batch system as well as the storage for interactive analyses. In this document, we will also give an outlook to future developments and concepts for the DESY high-throughput computing. In the ongoing evolution of the HTC batch system, we are exploring how to integrate anonymous jobs with the batch system as back-end for Function-as-a-Service workflows as well as an option for dynamic expansions to remote computing resources.

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