Large-Scale Rig for the Characterization of DCC at Sub-Atmospheric Pressure

2020 ◽  
Author(s):  
R. Lo Frano ◽  
A. Pesetti ◽  
D. Aquaro ◽  
M. Olcese
Keyword(s):  
Atmospheric Pressure ◽  
Large Scale ◽  
Fusion Reactor ◽  
Scale Up ◽  
Small Scale ◽  
Vacuum Vessel ◽  
Steam Condensation ◽  
Main Components ◽  
Under Construction ◽  
Experimental Rig

Abstract The Direct Contact Condensation (DCC) is the main phenomenon characterizing the steam condensation. It plays an important role for the operation of Vacuum Vessel Pressure Suppression System (VVPSS) tanks, particularly for managing the Ingress of Coolant Event (determining fusion reactor overpressurization). It is safety relevant (key) system of the fusion reactor because by condensing the steam generated during such accident event allows to damp the overpressure. This paper deals with experimental and theoretical analyses of the DCC at sub-atmospheric pressure. The similitude analysis was elaborated to scale up the experimental results obtained in the reduced scale facility: similitude laws are used for the design of large experimental rig. Correlations are defined starting from the water temperature and pressure variation already obtained in the small-scale rig. Furthermore, the experimental rig and its main components accordingly designed (and under construction at the University of Pisa) allow to study at large scale the steam condensation. The testing conditions are presented and discussed.

Agile Scrum Issues at Large-Scale Distributed Projects

2022 ◽  
pp. 388-398
Author(s):  
Ayesha Khalid ◽  
Shariq Aziz Butt ◽  
Tauseef Jamal ◽  
Saikat Gochhait
Keyword(s):  
Software Development ◽  
Large Scale ◽  
Software Industry ◽  
Small Scale ◽  
Project Organization ◽  
Distinctive Features ◽  
Main Components ◽  
Change Requests ◽  
Agile Model ◽  
Large Scale Project

The agile model is a very vast and popular model in use in the software industry currently. It changes the way software is developed. It was introduced in 2001 to overcome deficiencies of software development in a workshop arranged by researchers and practitioners who were involved with the agile concept. They introduced the complete agile manifesto. The agile model has main components that make it more viable for use in well-organized software development. One of these is scrum methodology. The reason for the agile-scrum popularity is its use for small-scale projects, making small teams and allows change requests at any stage of a project from the client. It works for client satisfaction. Instead of so much popularity and distinctive features, agile-scrum also has some limitations when used for large scale projects development that makes it less efficient for development. This article discusses the agile-scrum methodology and its limitations when using for large-scale project organization.

scholarly journals Combined measurement of velocity and temperature in liquid metal convection

2019 ◽  
Vol 876 ◽  
pp. 1108-1128 ◽  
Author(s):  
Till Zürner ◽  
Felix Schindler ◽  
Tobias Vogt ◽  
Sven Eckert ◽  
Jörg Schumacher
Keyword(s):  
Reynolds Number ◽  
Liquid Metal ◽  
Large Scale ◽  
Scale Up ◽  
Convection Cell ◽  
Small Scale ◽  
Convection Flow ◽  
Large Scale Circulation ◽  
Large Scale Flow ◽  
The Impact

Combined measurements of velocity components and temperature in a turbulent Rayleigh–Bénard convection flow at a low Prandtl number of $Pr=0.029$ and Rayleigh numbers of $10^{6}\leqslant Ra\leqslant 6\times 10^{7}$ are conducted in a series of experiments with durations of more than a thousand free-fall time units. Multiple crossing ultrasound beam lines and an array of thermocouples at mid-height allow for a detailed analysis and characterization of the complex three-dimensional dynamics of the single large-scale circulation roll in a cylindrical convection cell of unit aspect ratio which is filled with the liquid metal alloy GaInSn. We measure the internal temporal correlations of the complex large-scale flow and distinguish between short-term oscillations associated with a sloshing motion in the mid-plane as well as varying orientation angles of the velocity close to the top/bottom plates and the slow azimuthal drift of the mean orientation of the roll as a whole that proceeds on a time scale up to a hundred times slower. The coherent large-scale circulation drives a vigorous turbulence in the whole cell that is quantified by direct Reynolds number measurements at different locations in the cell. The velocity increment statistics in the bulk of the cell displays characteristic properties of intermittent small-scale fluid turbulence. We also show that the impact of the symmetry-breaking large-scale flow persists to small-scale velocity fluctuations thus preventing the establishment of fully isotropic turbulence in the cell centre. Reynolds number amplitudes depend sensitively on beam-line position in the cell such that different definitions have to be compared. The global momentum and heat transfer scalings with Rayleigh number are found to agree with those of direct numerical simulations and other laboratory experiments.

scholarly journals Optimisation of confinement in a fusion reactor using a nonlinear turbulence model

2018 ◽  
Vol 84 (2) ◽  
Author(s):  
E. G. Highcock ◽  
N. R. Mandell ◽  
M. Barnes ◽  
W. Dorland
Keyword(s):  
First Principles ◽  
Figure Of Merit ◽  
Large Scale ◽  
Unit Volume ◽  
Fusion Reactor ◽  
Small Scale ◽  
Zonal Flows ◽  
Novel Approach ◽  
First Time ◽  
Turbulent Cascade

The confinement of heat in the core of a magnetic fusion reactor is optimised using a multidimensional optimisation algorithm. For the first time in such a study, the loss of heat due to turbulence is modelled at every stage using first-principles nonlinear simulations which accurately capture the turbulent cascade and large-scale zonal flows. The simulations utilise a novel approach, with gyrofluid treatment of the small-scale drift waves and gyrokinetic treatment of the large-scale zonal flows. A simple near-circular equilibrium with standard parameters is chosen as the initial condition. The figure of merit, fusion power per unit volume, is calculated, and then two control parameters, the elongation and triangularity of the outer flux surface, are varied, with the algorithm seeking to optimise the chosen figure of merit. A twofold increase in the plasma power per unit volume is achieved by moving to higher elongation and strongly negative triangularity.

Radial Profiles of Particle Velocity in a Large Scale CFB Downer

2004 ◽  
Vol 2 (1) ◽  
Author(s):  
Zhen Qian ◽  
Minghui Zhang ◽  
Hao Yu ◽  
Fei Wei
Keyword(s):  
Particle Velocity ◽  
Large Scale ◽  
Circulating Fluidized Bed ◽  
Scale Up ◽  
Radial Profile ◽  
Small Scale ◽  
Wall Region ◽  
Radial Profiles ◽  
Peak Value ◽  
Near Wall

Radial profiles of particle velocity in a large scale (418 mm I.D.) downward Circulating Fluidized Bed (CFB downer) were obtained via a Laser Doppler Velocimetry (LDV) system. Results show that particle velocity is gradually increasing along the radial direction and there exists a peak value in the near wall region. Such unique radial profile shape can be explained by the solids accumulating trend in the near wall region of the downer. Experiment results in this large scale downer are also compared with those obtained by other researchers in small scale units so as to investigate the scale-up effect on the radial particle velocity distribution in the downer.

scholarly journals Scaling the INGO: What the Development and Expansion of Canadian INGOs Tells Us

2020 ◽  
Vol 9 (8) ◽  
pp. 140
Author(s):  
Logan Cochrane ◽  
John-Michael Davis
Keyword(s):  
Large Scale ◽  
Scale Up ◽  
Critical Factor ◽  
Individual Case ◽  
Government Funding ◽  
Future Research ◽  
Small Scale ◽  
Non Governmental Organizations ◽  
Original Dataset ◽  
Organizational Age

The literature on international non-governmental organizations (INGOs) has focused primarily on large INGOs, which capture the majority of total INGO spending but represent a small number of total INGOs. Over the past two decades, the number of INGOs has more than tripled throughout the global North, which has ushered in a decentralization of the sector as an emerging class of small- and medium-sized INGOs increasingly share the same space once occupied solely by large INGOs. This study focuses on these INGOs in transition to explore how they differ from large INGOs that receive significant government funding and their pathways to scale. Using an original dataset of 1371 Canadian INGOs, we explored comparative differences related to funding sources, overhead, organizational age, country coverage, staff, and religion between the transitioning and small-scale INGOs. Our results identified several general insights for how INGOs transition: (1) Large INGOs are less likely to articulate a religious motivation, which may impede government funding; (2) INGOs are more likely to be headquartered in Ontario, which is closer to federal government offices; (3) low overhead expenditures inhibit small-scale INGOs from transitioning to medium- and large-scale INGOs; (4) organizational age plays a critical factor to scale-up as INGOs increase their experience and expertise; (5) generous compensation to attract talented staff offers an under-valued pathway to scale. Finally, our results demonstrate the diversity among INGOs in Canada and problematizes singular scale-up pathways, while underscoring the necessity of future research to explore scaling strategies through individual case studies.

scholarly journals STUDY THE GROWTH KINETICS OF PEDIOCOCCUS ACIDILACTICI WITH ESTIMATION OF KINETIC PARAMETERS AND APPLIED IN LARGE SCALE PEDIOCIN PRODUCTION

2016 ◽  
Vol 9 (5) ◽  
pp. 130
Author(s):  
Barnali Mandal
Keyword(s):  
Experimental Data ◽  
Lactic Acid ◽  
Kinetic Parameters ◽  
Growth Kinetics ◽  
Large Scale ◽  
Scale Up ◽  
Small Scale ◽  
Pediococcus Acidilactici ◽  
Monod Model ◽  
Kinetics Of

ABSTRACTObjectives: The aim of the study was to determine the growth kinetics of Pediococcus acidilactici using a mathematical model for large scale pediocinproduction.Methods: Growth kinetics of P. acidilactici has been studied for pediocin production in small scale batch fermenter (Erlenmeyer flask) using meatprocessing waste medium. The experiments have been conducted with varying the concentrations of glucose, protein, and lactic acid. A mathematicalmodel has been developed to describe growth rate, products (pediocin and lactic acid) formation rate, and substrates (glucose and protein) utilizationrate. Monod model for dual substrates (glucose and protein) has been used with considering lactic acid inhibition. Luedeking-Piret model has beenintroduced to describe the production of pediocin and lactic acid.Results: The values of kinetic parameters have been determined using experimental data and model equations. The model prediction has beencompared satisfactorily with the experimental data for the validation of the model.Conclusions: The developed model was satisfactorily validated to scale up the production of pediocin.Keywords: Pediococcus acidilactici, Pediocin, Meat processing waste, Monod model, Luedeking-Piret model, Kinetic parameters.

Dispersive Mixing Consideration of Twin-Screw Compounding Scale-Up Methodologies

2015 ◽  
Author(s):  
Benjamin Dryer ◽  
Graeme Fukuda ◽  
Jake Webb ◽  
David I. Bigio ◽  
Mark Wetzel ◽  
...  
Keyword(s):  
Material Properties ◽  
Large Scale ◽  
Scale Up ◽  
Polymer Melt ◽  
Operating Conditions ◽  
Small Scale ◽  
Twin Screw ◽  
Industry Practice ◽  
Break Up ◽  
Dispersive Mixing

Twin-screw polymer extrusion has shown increased utility for creating composite materials. However, in order to achieve the desired product properties, sufficient mixing is essential. Dispersive mixing, or the breaking-up of particle agglomerates, is critical to create filled compounds with the required material properties. In a twin-screw compounding process, the Residence Stress Distribution (RSD) has been used to quantify the dispersive mixing induced by the stresses in the polymer melt. These stresses are quantified by the percent break-up of stress-sensitive polymeric beads. It was found that the amount of material that experiences the critical stress is a function of the operating conditions of screw speed and specific throughput [1]. The quantification of dispersive mixing allows for better control of a compounding process and can be used to design new processes. During the development of a new compounding process, screw geometries and operating conditions are often refined on a laboratory-scale extruder and then scaled up to a manufacturing level. Scale-up rules are used to translate the operating conditions of a process to different sizes of extruders. In a compounding process, the goal when scaling-up is to maintain the same material properties on both scales by achieving equivalent mixing. The RSD methodology can be used to evaluate the effectiveness of scale-up rules by comparison between two or more scales. This paper will demonstrate the utility of the RSD in evaluation of two unique scale-up rules. Conventional industry practice is based on the volumetric flow comparison between extruders. The proposed approach demonstrates that in order to maintain equivalent dispersive mixing between different sizes of extruders, the degree of fill, or the percent drag flow (%DF), must be kept equivalent in the primary mixing region. The effectiveness of both rules has been evaluated by experimental application of the RSD methodology. A design of experiment approach was used to generate predictive equations for each scale-up rule that were compared to the behavior of the original small-scale extruder. Statistical comparison of the two scale-up rules showed that the %DF rule predicted operating conditions on the large-scale extruder that produced percent break-up behavior more similar to the small-scale behavior. From these results, it can be concluded that the %DF scale-up rule can be used to accurately scale operating conditions between different-sized extruders to ensure similar dispersive mixing between two processes. This will allow for greater accuracy when recreating the material properties of a small-scale twin-screw compounding process on a larger, mass production machine.

Experimental Study of Steam Pressure Suppression by Condensation in a Water Tank at Sub-Atmospheric Pressure

2016 ◽  
Author(s):  
Dahmane Mazed ◽  
Rosa Lo Frano ◽  
Donato Aquaro ◽  
Daniele Del Serra ◽  
Igor Sekachev ◽  
...  
Keyword(s):  
Experimental Study ◽  
Atmospheric Pressure ◽  
High Efficiency ◽  
Saturation Pressure ◽  
Steam Pressure ◽  
Operating Conditions ◽  
Water Tank ◽  
Vacuum Vessel ◽  
Steam Condensation ◽  
Suppression System

The Vacuum Vessel Pressure Suppression System (VVPSS), a key safety system of the ITER plant, is designed to protect the Vacuum Vessel (VV) from over pressure occurring in the case of LOCA (Loss Of Coolant Accident) or other pressurizing accidents such as LOVA (Loss Of Vacuum Accident). The steam condensation in the Suppression Tanks (main elements of the VVPSS system), occurs at sub-atmospheric pressure. The steam condensation, at pressures equal or greater than the atmospheric, has been numerically analyzed and experimentally investigated in the past in order to optimize the design of the pressure suppression system of boiling water nuclear reactors. However, very limited experimental data is available concerning the steam condensation in a water tank at sub-atmospheric pressure. In order to analyze the steam condensation in these operating conditions, an experimental study, funded by ITER Organization, is conducted at the Department of Civil and Industrial Engineering (DICI) of University of Pisa. The tests analyze the condensation of saturated or superheated steam at sub-atmospheric pressures (4.2 kPa and slightly above the water vapour saturation pressure), and pool temperature up to 50°C at several heights of water head. The experimental facility, to perform this study, has been set up with a significant scaling factor regarding the full size installation at ITER. In this paper the experimental rig, the conditions of the experiments, and the test matrix are presented. The temperature and pressure measurements with details of the data acquisition system are described. The tests were performed at different patterns of the sparger exit holes (1, 3 and 9) and for three steam mass flow rates per one hole. The results show very high efficiency of condensation for all examined conditions. Finally, a comparison between the condensation regimen at sub-atmospheric and at atmospheric pressure is discussed.

Ultrasonic-Impregnation for Fiber-Reinforced Thermoplastic Prepreg Production

2017 ◽  
Vol 742 ◽  
pp. 17-24
Author(s):  
Steve Sockol ◽  
Christoph Doerffel ◽  
Juliane Mehnert ◽  
Gerd Zwinzscher ◽  
Steffen Rein ◽  
...  
Keyword(s):  
Large Scale ◽  
Matrix Material ◽  
Scale Up ◽  
Small Scale ◽  
Hydraulic Pressure ◽  
Scale Production ◽  
Fiber Reinforced ◽  
Technological Parameters ◽  
Ultrasonic Technology ◽  
High Processing

Fiber-reinforced thermoplastics have a high potential for big scale light weight process applications due to low processing times and recyclability. Further advantages are the low emissions during the manufacturing process and beneficial handling and storing properties of the semi finished materials. Thermoplastic composites are made of reinforcement fibers and a thermoplastic polymer matrix by applying two essential sub processes: (1) melting of the matrix-material and (2) impregnating the textile component with molten matrix-material. At present state of art both sub-processes are applied by using double-belt-presses, characterized by high processing temperatures and high processing forces. Therefore, a large amount of energy is needed to create the necessarily high compaction forces and temperatures with hydraulic cylinders and electric heating. Convection, infrared-radiation and the cooling (dynamic) of tempered machine parts leads to a significant dissipation of energy. Especially the process for generating the hydraulic pressure has a low level of efficiency. Therefore, in respect to economic and ecologic reasons, novel energy-efficient impregnation processes need to be investigated and developed. The represented novel impregnation process is based on ultrasonic technology. A stack of polymer film (outer layers) and a textile ply (inner layer) is formed and the energy is applied with an ultrasonic sonotrode. The efficient, fast and strongly concentrated energy application into the thermoplastic films allows the development of novel and highly flexible machine concepts. These can be used for development of small scale up to large scale production processes. The ultrasonic-technology allows a continuous impregnation of the textile component with molten matrix-material. A custom-designed prototype was developed. First material samples were produced and the technological parameters studied. A characterization of the experimental results, material samples, prototype machine and process is the focus of this paper.

scholarly journals Leveraging Deep Neural Networks to Map Caribou Lichen in High-Resolution Satellite Images Based on a Small-Scale, Noisy UAV-Derived Map

2021 ◽  
Vol 13 (14) ◽  
pp. 2658
Author(s):  
Shahab Jozdani ◽  
Dongmei Chen ◽  
Wenjun Chen ◽  
Sylvain G. Leblanc ◽  
Christian Prévost ◽  
...  
Keyword(s):  
High Resolution ◽  
Spatial Resolution ◽  
Large Scale ◽  
False Positive Rate ◽  
Scale Up ◽  
Small Sample ◽  
Small Scale ◽  
Sample Site ◽  
High Resolution Satellite Images ◽  
Very High

Lichen is an important food source for caribou in Canada. Lichen mapping using remote sensing (RS) images could be a challenging task, however, as lichens generally appear in unevenly distributed, small patches, and could resemble surficial features. Moreover, collecting lichen labeled data (reference data) is expensive, which restricts the application of many robust supervised classification models that generally demand a large quantity of labeled data. The goal of this study was to investigate the potential of using a very-high-spatial resolution (1-cm) lichen map of a small sample site (e.g., generated based on a single UAV scene and using field data) to train a subsequent classifier to map caribou lichen over a much larger area (~0.04 km2 vs. ~195 km2) and a lower spatial resolution image (in this case, a 50-cm WorldView-2 image). The limited labeled data from the sample site were also partially noisy due to spatial and temporal mismatching issues. For this, we deployed a recently proposed Teacher-Student semi-supervised learning (SSL) approach (based on U-Net and U-Net++ networks) involving unlabeled data to assist with improving the model performance. Our experiments showed that it was possible to scale-up the UAV-derived lichen map to the WorldView-2 scale with reasonable accuracy (overall accuracy of 85.28% and F1-socre of 84.38%) without collecting any samples directly in the WorldView-2 scene. We also found that our noisy labels were partially beneficial to the SSL robustness because they improved the false positive rate compared to the use of a cleaner training set directly collected within the same area in the WorldView-2 image. As a result, this research opens new insights into how current very high-resolution, small-scale caribou lichen maps can be used for generating more accurate large-scale caribou lichen maps from high-resolution satellite imagery.

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