scholarly journals On the dynamics of starting plumes

2017 ◽  
Vol 833 ◽  
Author(s):  
N. Bhamidipati ◽  
Andrew W. Woods
Keyword(s):  
Laboratory Experiments ◽  
Added Mass ◽  
Rate Of Change ◽  
Small Scale ◽  
Maximum Height ◽  
Ambient Fluid ◽  
A Value ◽  
Proposed Model ◽  
The Difference ◽  
Reasonable Description

We explore the dynamics of starting plumes by analysis of a series of new small-scale laboratory experiments combined with a theoretical model for mass, momentum, and buoyancy conservation. We find that the head of the plume ascends with a speed which is approximately 0.6 times the characteristic speed of the fluid in the following steady plume, in accord with Turner (J. Fluid Mech., vol. 13 (03), 1962, pp. 356–368), and so the fluid released from the source eventually catches the head of the flow. On reaching the top of the plume it recirculates and mixes in the plume head. We estimate that approximately $0.61\pm 0.04$ of the total buoyancy released from the source accumulates in the plume head, with the remainder in the following steady plume. Using measurements of the volume of the head, we estimate that a fraction $0.16\pm 0.08$ of the volume of the head is entrained directly from the ambient, with the remainder of the fluid in the head being supplied by the following steady plume. These results imply that the buoyancy force exerted on the plume head plus the momentum flux supplied by the following plume exceeds the rate of change of momentum of the plume head even including the added mass of the plume head. We propose that the difference is associated with a drag force resulting from the displacement of ambient fluid around the plume head. Using our experimental data, we estimate that the drag coefficient $C_{d}$ has a value $4.2\pm 1.4$, with the range in values associated with the uncertainty in our estimate of entrainment of fluid directly into the plume head. As a test, the proposed model is shown to provide a reasonable description of a starting plume rising through a stratified environment in the region below the maximum height of rise of the associated steady plume, although, above this point, the shape of the plume head changes and the model breaks down.

scholarly journals Self-Esteem depends on beliefs about the rate of change of social approval

2021 ◽  
Author(s):  
Alexis An Yee Low ◽  
William John Telesfor Hopper ◽  
Ilinca Angelescu ◽  
Liam Mason ◽  
Geert-Jan Will ◽  
...  
Keyword(s):  
Associative Learning ◽  
Computational Modelling ◽  
Self Esteem ◽  
Rate Of Change ◽  
Social Approval ◽  
Social Evaluation ◽  
A Value ◽  
The Difference ◽  
New Evidence ◽  
Better Than

A major challenge in understanding the neurobiological basis of psychiatric disorders is to rigorously quantify subjective metrics that lie at the core of mental illness, such as low self-esteem. Self-esteem can be conceptualized as a ‘gauge of social approval’ that increases in response to approval and decreases in response to disapproval. Computational modelling approaches have shown that learning signals that represent the difference between received and expected social approval drive changes in self-esteem. However, it is unclear whether self-esteem based on social approval should be understood as a value updated through associative learning, or as a belief about the self, updated by new evidence depending on how strongly it is held. Our results show that belief-based models explain self-esteem dynamics in response to social evaluation better than associative learning models. Importantly, our findings suggest that in the short term, self-esteem signals the direction and rate of change of one’s beliefs about approval within a group, rather than one’s social position.

Simulation of a lock-release gravity current based on a non-hydrostatic model

2019 ◽  
Vol 19 (6) ◽  
pp. 1802-1808
Author(s):  
Xueqing Zhang ◽  
Jinzhen Yu ◽  
Yilei Feng
Keyword(s):  
Laboratory Experiments ◽  
Gravity Current ◽  
Wave Model ◽  
Ambient Fluid ◽  
Forward Movement ◽  
Circular Flow ◽  
Front Position ◽  
Hydrostatic Model ◽  
The Difference ◽  
Better Than

Abstract Gravity currents are important in many fields, including the estuarine sciences, meteorology and hydraulic engineering. The NHWAVE (non-hydrostatic wave) model was applied to simulate the detailed interface structure between a lock-release gravity current and the ambient fluid. The simulated structures, including the front height, front position and velocity of the current, are consistent with the results of laboratory experiments. However, the internal structure of the current is different from that revealed by previous research. The Kelvin–Helmholtz phenomenon in the interface and the interface vortices were successfully captured by the NHWAVE model. The difference in velocity between the front and rear vortices leads to entrainment, further causing changes in the shapes and amount of vortices. Flow field results obtained by the NHWAVE model reveal the existence of a significant circular flow, as well as some small eddies within it. The significant circular flow supports the forward movement of the current, whereas the small eddies reflect interface vortices. In contrast, hydrostatic simulation with the same model settings fails to capture the vortices. This research shows that the NHWAVE model performs better than a hydrostatic model when simulating the Kelvin–Helmholtz instability phenomenon and vortex entrainment in a lock-release gravity current.

scholarly journals STRUKTUR MIKRO DAN SIFAT MEKANIS ALUMINIUM (Al-Si) PADA PROSES PENGECORAN MENGGUNAKAN CETAKAN LOGAM, CETAKAN PASIR DAN CETAKAN CASTABLE

POROS ◽  
2017 ◽  
Vol 14 (2) ◽  
pp. 88
Author(s):  
Martinus Mandala ◽  
Eddy Siradj ◽  
Sofyan Djamil
Keyword(s):  
Large Scale ◽  
Raw Materials ◽  
Raw Material ◽  
Small Scale ◽  
Cast Aluminum ◽  
Metal Mold ◽  
The Public ◽  
A Value ◽  
The Difference ◽  
Casting Industry

Abstract: Aluminum foundry is one of the business sectors that to much in demand by the public, ranging from small scale to large scale . Through remelting process, some small-scale aluminum casting industry, using raw materials of used aluminum as the main raw material. Some of the cast products are required to have good quality to comply with quality standards on its use. This study aims to look at the difference in quality of cast aluminum (Al-Si) using three types of mold, the metal mold, sand mold, and the mold castable by testing the mechanical properties of materials that impact and Brinell hardness testing. The method used was experimental or trial. The results obtained are the result cast using a metal mold has a hardness value of the highest of 63 HBN, with a value of impact 37

Values Underlying Preferences for Adaptive Governance in a Chilean Small-Scale Fishing Community

2020 ◽  
Author(s):  
Sarah A. Ebel ◽  
Christine M. Beitl ◽  
Michael P. Torre
Keyword(s):  
Environmental Change ◽  
Environmental Governance ◽  
Small Scale ◽  
Adaptive Governance ◽  
Fishing Community ◽  
A Value ◽  
Ways Of Life ◽  
Value Frames

Environmental change requires individuals and institutions to facilitate adaptive governance. However, facilitating adaptive governance may be difficult because resource users’ perceptions of desirable ways of life vary. These perceptions influence preferences related to environmental governance and may stem from the ways individuals subjectively value their work and their connections to their environment. This paper uses a value-based approach to examine individual and institutional preferences for adaptive governance in Carelmapu, Chile. We show that two groups had different value frames rooted in divergent ontologies which influenced their actions related to adaptive governance, creating conflict.

Observation and Experimentation

2018 ◽  
Author(s):  
Massimiliano Di Ventra
Keyword(s):  
Laboratory Experiments ◽  
The Difference

This chapter expands on the previous one on the role of experiments in Science. It explains the difference between observations of phenomena and controlled laboratory experiments.

scholarly journals The Water Footprint of Primary and Secondary Processing of Beef from Different Cattle Breeds: A Value Fraction Allocation Model

2021 ◽  
Vol 13 (12) ◽  
pp. 6914
Author(s):  
Frikkie Alberts Maré ◽  
Henry Jordaan
Keyword(s):  
Water Footprint ◽  
Negative Relationship ◽  
High Water ◽  
Allocation Model ◽  
Cattle Breeds ◽  
A Value ◽  
Average Production ◽  
High Water Intake ◽  
The Difference ◽  
By Products

The high water intake and wastewater discharge of slaughterhouses have been a concern for many years. One neglected factor in previous research is allocating the water footprint (WF) to beef production’s different products and by-products. The objective of this article was to estimate the WF of different cattle breeds at a slaughterhouse and cutting plant and allocate it according to the different cuts (products) and by-products of beef based on the value fraction of each. The results indicated a negative relationship between the carcass weight and the processing WF when the different breeds were compared. Regarding a specific cut of beef, a kilogram of rib eye from the heaviest breed had a processing WF of 614.57 L/kg, compared to the 919.91 L/kg for the rib eye of the lightest breed. A comparison of the different cuts indicated that high-value cuts had higher WFs than low-value cuts. The difference between a kilogram of rib eye and flank was 426.26 L/kg for the heaviest breed and 637.86 L/kg for the lightest breed. An option to reduce the processing WF of beef is to lessen the WF by slaughtering heavier animals. This will require no extra investment from the slaughterhouse. At the same time, the returns should increase as the average production inputs per kilogram of output (carcass) should reduce, as the slaughterhouse will process more kilograms.

scholarly journals Visual Simulation of Detailed Turbulent Water by Preserving the Thin Sheets of Fluid

Symmetry ◽  
2018 ◽  
Vol 10 (10) ◽  
pp. 502 ◽  
Author(s):  
Jong-Hyun Kim ◽  
Wook Kim ◽  
Young Kim ◽  
Jung Lee
Keyword(s):  
Turbulent Flows ◽  
Visual Simulation ◽  
Numerical Dissipation ◽  
Small Scale ◽  
Thin Sheets ◽  
Global Flow ◽  
Low Mass ◽  
The Difference ◽  
Water Simulation ◽  
Turbulent Water

When we perform particle-based water simulation, water particles are often increased dramatically because of particle splitting around breaking holes to maintain the thin fluid sheets. Because most of the existing approaches do not consider the volume of the water particles, the water particles must have a very low mass to satisfy the law of the conservation of mass. This phenomenon smears the motion of the water, which would otherwise result in splashing, thereby resulting in artifacts such as numerical dissipation. Thus, we propose a new fluid-implicit, particle-based framework for maintaining and representing the thin sheets and turbulent flows of water. After splitting the water particles, the proposed method uses the ghost density and ghost mass to redistribute the difference in mass based on the volume of the water particles. Next, small-scale turbulent flows are formed in local regions and transferred in a smooth manner to the global flow field. Our results show us the turbulence details as well as the thin sheets of water, thereby obtaining an aesthetically pleasing improvement compared with existing methods.

Male-biased sex ratio in Argulus canadensis Wilson, 1916 (Crustacea: Branchiura) ectoparasitic on sticklebacks

1989 ◽  
Vol 67 (8) ◽  
pp. 2078-2080 ◽  
Author(s):  
Robert Poulin ◽  
Gerard J. FitzGerald
Keyword(s):  
Salt Marsh ◽  
Sex Ratio ◽  
Laboratory Experiments ◽  
Fish Predation ◽  
Reproductive Behaviour ◽  
Egg Deposition ◽  
Alternative Hypotheses ◽  
Biased Sex Ratio ◽  
The Difference ◽  
Fish Hosts

Females of the ectoparasitic crustacean Argulus canadensis must leave their fish hosts at least temporarily to deposit their eggs on the substrate. To test the hypothesis that this difference in reproductive behaviour between the two sexes could result in male-biased sex ratios on their stickleback hosts, we sampled sticklebacks in tide pools of a Quebec salt marsh from early July to early September 1986. During this period, fish harboured significantly more male than female A. canadensis. Laboratory experiments were done to test two alternative hypotheses offered to explain this biased sex ratio. The first hypothesis was that male A. canadensis were more successful than females in attacking their stickleback hosts; however, we found no differences in attack success on their hosts between the two parasite sexes. The second hypothesis was that sticklebacks ate more female than male A. canadensis. Although males were less vulnerable to fish predation than females, the difference was not significant. We conclude that sexual differences in reproductive behaviour, i.e., egg deposition behaviour of females, can account for the male-biased sex ratio of A. canadensis on sticklebacks.

Heat-flow experiments in liquid 4He with a variable cylindrical geometry

1987 ◽  
Vol 174 ◽  
pp. 209-231 ◽  
Author(s):  
H. Gao ◽  
G. Metcalfe ◽  
T. Jung ◽  
R. P. Behringer
Keyword(s):  
Cylindrical Geometry ◽  
Small Scale ◽  
Onset Of Convection ◽  
Aspect Ratios ◽  
A Value ◽  
Prandtl Numbers ◽  
Convection Rolls ◽  
Flow Experiments ◽  
Increasing Function ◽  
Good Agreement

This paper first describes an apparatus for measuring the Nusselt number N versus the Rayleigh number R of convecting normal liquid 4He layers. The most important feature of the apparatus is its ability to provide layers of different heights d, and hence different aspect ratios [Gcy ]. The horizontal cross-section of each layer is circular, and [Gcy ] is defined by [Gcy ] = D/2d where D is the diameter of the layer. We report results for 2.4 [les ] [Gcy ] [les ] 16 and for Prandtl numbers Pr spanning 0.5 [lsim ] Pr [lsim ] 0.9 These results are presented in terms of the slope N1 = RcdN/dR evaluated just above the onset of convection at Rc. We find that N1 is only a slowly increasing function of [Gcy ] in the range 6 [lsim ] [Gcy ] [lsim ] 16, and that it has a value there which is quite close to 0.72. This value of N1 is in good agreement with variational calcuations by Ahlers et al. (1981) pertinent to parallel convection rolls in cylindrical geometry. Particularly for [Gcy ] [lsim ] 6, we find additional small-scale structure in N1 associated with changes in the number of convection rolls with changing [Gcy ]. An additional test of the linearzied hydrodynamics is given by measurements of Rc. We find good agreement between theory and our data for Rc.

Modeling and simulation of saturated double rotor induction machine

2018 ◽  
Vol 37 (3) ◽  
pp. 1139-1165
Author(s):  
Koosha Choobdari Omran ◽  
Ali Mosallanejad
Keyword(s):  
Temperature Effects ◽  
Power Efficiency ◽  
Reactive Power ◽  
Induction Machine ◽  
Transient Behavior ◽  
State Equations ◽  
Content Type ◽  
Proposed Model ◽  
The Difference ◽  
Park Transformation

Purpose Double rotor induction machine (DRIM) is a particular type of induction machine (IM) that has been introduced to improve the parameters of the conventional IM. The purpose of this study is to propose a dynamic model of the DRIM under saturated and unsaturated conditions by using the equations obtained in this paper. Also, skin and temperature effects are considered in this model. Design/methodology/approach First, the DRIM structure and its performance will be briefly reviewed. Then, to realize the DRIM model, the mathematical equations of the electrical and mechanical part of the DRIM will be presented by state equations in the q-d axis by using the Park transformation. In this paper, the magnetizing fluxes saturation is included in the DRIM model by considering the difference between the amplitudes of the unsaturated and saturated magnetizing fluxes. The skin and temperature effects are also considered in this model by correcting the rotor and stator resistances values during operation. Findings To evaluate the effects of the saturation and skin effects on DRIM performance and validate the model, the machine is simulated with/without consideration of saturation and skin effects by the proposed model. Then, the results, including torque, speed, stator and rotor currents, active and reactive power, efficiency, power factor and torque-speed characteristic, are compared. In addition, the performance of the DRIM has been investigated at different speed conditions and load variations. The proposed model is developed in Matlab/Simulink for the sake of validation. Originality/value This paper presents an understandable model of DRIM with and without saturation, which can be used to analyze the steady-state and transient behavior of the motor in different situations.

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