scholarly journals Differential Diffusivity Effects in Reactive Convective Dissolution

Fluids ◽  
2018 ◽  
Vol 3 (4) ◽  
pp. 83 ◽  
Author(s):  
V. Loodts ◽  
H. Saghou ◽  
B. Knaepen ◽  
L. Rongy ◽  
A. De Wit
Keyword(s):  
Diffusion Coefficients ◽  
Reaction Rate ◽  
Chemical Species ◽  
Mixing Zone ◽  
Simultaneous Presence ◽  
Dynamic Effects ◽  
Density Profiles ◽  
Differential Diffusion ◽  
Different Types ◽  
Double Diffusive

When a solute A dissolves into a host fluid containing a reactant B, an A + B → C reaction can influence the convection developing because of unstable density gradients in the gravity field. When A increases density and all three chemical species A, B and C diffuse at the same rate, the reactive case can lead to two different types of density profiles, i.e., a monotonically decreasing one from the interface to the bulk and a non-monotonic profile with a minimum. We study numerically here the nonlinear reactive convective dissolution dynamics in the more general case where the three solutes can diffuse at different rates. We show that differential diffusion can add new dynamic effects like the simultaneous presence of two different convection zones in the host phase when a non-monotonic profile with both a minimum and a maximum develops. Double diffusive instabilities can moreover affect the morphology of the convective fingers. Analysis of the mixing zone, the reaction rate, the total amount of stored A and the dissolution flux further shows that varying the diffusion coefficients of the various species has a quantitative effect on convection.

An Approach for the Dynamics of Robotic Manipulators With Structural Flexibility of Links and Joints

1997 ◽  
Author(s):  
J. Kövecses ◽  
R. G. Fenton ◽  
W. L. Cleghorn
Keyword(s):  
Equations Of Motion ◽  
Robotic Manipulators ◽  
Structural Flexibility ◽  
Flexible Link ◽  
Dynamic Effects ◽  
Flexible Joint ◽  
Modeling And Analysis ◽  
Discrete Parameter ◽  
Rigid Link ◽  
Different Types

Abstract In this paper, an approach is presented for the dynamic modeling and analysis of robotic manipulators having structural flexibility in the links and joints. The formulation allows the user to include different types of flexibilities, as required. This approach includes the dynamic effects of joint driving systems by considering the mass and moments of inertia of their elements, the rotor-link interactions, and the gear reduction ratios; all of which can have significant influences on the behavior of the manipulator. Both distributed-discrete and discretized-discrete parameter models of a robot can be analysed. In the discretized-discrete case, dynamic equations of motion are developed for four model types: rigid link - rigid joint, rigid link - flexible joint, flexible link - rigid joint, and flexible link - flexible joint. An example of a two-link manipulator is considered. Simulation results are presented for different models (flexible joint - rigid link, rigid joint - flexible link, flexible joint - flexible link) of the manipulator. The computations show the influence of joint and link flexibilities on the manipulator performance.

Numerical Simulation of Impacts of Different Types of Air Duct Outlets on Ventilation Efficiency

2013 ◽  
Vol 438-439 ◽  
pp. 1098-1103
Author(s):  
Chun Zi Nan ◽  
Ji Ming Ma ◽  
Luo Zhao
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Velocity Distribution ◽  
Flow Velocity ◽  
Numerical Method ◽  
Concentration Effect ◽  
Mixing Zone ◽  
Mixing Effect ◽  
Ventilation Efficiency ◽  
Different Types

To enhance the exhaust efficiency during ventilation, three types of air duct outlets were imported. According to the characteristics of velocity distribution simulated by numerical method, the flow field is divided into the mixing zone and the exhaust zone. The gradual contracted air duct outlet can enhance the mixing effect between fresh air and smoke. In the exhaust zone, however, the flow velocity on the upper section of the tunnel is weakened, which is unfavorable for smoke exhaust. Gradual expanded air duct outlet, on the contrary, may weaken the concentration effect of the airflow. The flow velocity on the upper section of the tunnel is increased in the exhaust zone, thus the flow field is more homogenized, which is in favor of smoke exhaust.

scholarly journals Phase Stability Diagrams for High Temperature Corrosion Processes

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
J. J. Ramos-Hernandez ◽  
J. Porcayo-Calderon ◽  
V. M. Salinas-Bravo ◽  
C. D. Arrieta-Gonzalez ◽  
J. G. Gonzalez-Rodriguez ◽  
...  
Keyword(s):  
High Temperature ◽  
Phase Stability ◽  
Fossil Fuels ◽  
Chemical Species ◽  
Data Bases ◽  
Fused Salts ◽  
Stability Diagrams ◽  
Different Types ◽  
Vanadium Salts ◽  
Engineering Alloys

Corrosion phenomena of metals by fused salts depend on chemical composition of the melt and environmental conditions of the system. Detail knowledge of chemistry and thermodynamic of aggressive species formed during the corrosion process is essential for a better understanding of materials degradation exposed to high temperature. When there is a lack of kinetic data for the corrosion processes, an alternative to understand the thermodynamic behavior of chemical species is to utilize phase stability diagrams. Nowadays, there are several specialized software programs to calculate phase stability diagrams. These programs are based on thermodynamics of chemical reactions. Using a thermodynamic data base allows the calculation of different types of phase diagrams. However, sometimes it is difficult to have access to such data bases. In this work, an alternative way to calculate phase stability diagrams is presented. The work is exemplified in the Na-V-S-O and Al-Na-V-S-O systems. This system was chosen because vanadium salts is one of the more aggressive system for all engineering alloys, especially in those processes where fossil fuels are used.

Stability of Turing-Type Patterns in a Reaction–Diffusion System with an External Gradient

2017 ◽  
Vol 27 (01) ◽  
pp. 1750003 ◽  
Author(s):  
Tilmann Glimm ◽  
Jianying Zhang ◽  
Yun-Qiu Shen
Keyword(s):  
Diffusion Coefficients ◽  
Chemical Species ◽  
Reaction Diffusion ◽  
Spatial Dimension ◽  
Reaction Diffusion Equations ◽  
Generic Model ◽  
Bifurcation Diagrams ◽  
Analytic Approximations ◽  
Small Parameters ◽  
The Stability

We investigate the stability of Turing-type patterns in one spatial dimension in a system of reaction–diffusion equations with a term depending linearly on the spatial position. The system is a generic model of two interacting chemical species where production rates are dependent on a linear external gradient. This is motivated by mathematical models in developmental biology. In a previous paper, we found analytic approximations of Turing-like steady state patterns. In the present article, we derive conditions for the stability of these patterns and show bifurcation diagrams in two small parameters related to the slope of the external gradient and the ratio of the diffusion coefficients.

The managerial challenge of business interaction: behind the market façade

IMP Journal ◽  
2016 ◽  
Vol 10 (1) ◽  
pp. 154-171 ◽  
Author(s):  
Håkan Håkansson ◽  
David Ford
Keyword(s):  
Large Scale ◽  
Research Programme ◽  
Business Relationships ◽  
Dynamic Effects ◽  
Content Type ◽  
General Management ◽  
Different Types ◽  
Challenges And Opportunities ◽  
A Company ◽  
Practical Implications

Purpose – The purpose of this paper is to address three aspects of the managerial challenge that arises from the process of business interaction: the diversity of interaction; the dynamic effects of interaction; and the integration of interaction into company operations and strategy. The paper develops a typology which characterizes different types of interaction in order to identify the managerial issues they represent. Design/methodology/approach – The paper is based on the empirical research programme of the IMP Group (impgroup.org) and on a recent large scale research project within that programme. Findings – The paper seeks to identify the dynamic effects of each type of interaction on the resources and activities involved in it and address the implications that these effects have for management. Finally, the paper discusses how the challenges and opportunities presented by business interaction can be integrated into the general management of a company. Research limitations/implications – The paper is mainly based on detailed empirical observations focusing some special features. Focusing other aspects would give another result. Practical implications – Important for all companies having important business relationships. Originality/value – Gives a new view of managerial challenges related to the variety in business relationships.

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