scholarly journals Potential uses of Numerical Simulation for the Modelling of Civil Conflict

2017 ◽  
Vol 23 (1) ◽  
Author(s):  
Lucy Burton ◽  
Shane D. Johnson ◽  
Alex Braithwaite
Keyword(s):  
Numerical Simulation ◽  
New York ◽  
Civil Wars ◽  
Numerical Models ◽  
Civil Conflict ◽  
Relative Power ◽  
Asymmetric Warfare ◽  
Simulation Techniques ◽  
Stochastic Events ◽  
Conflict Outcomes

AbstractThis paper explores ways in which civil conflict can be simulated using numerical methods. A general two-party model of conflict is developed by extending an approach proposed by [Christia, F., (2012), Alliance Formation in Civil Wars, Cambridge University Press, New York], which is based on a metric of the ‘relative power’ that exists between the state and a rebel group. Various definitions of relative power are considered and one of these is chosen to illustrate different types of two-sided armed conflict, namely direct-fire, guerrilla and asymmetric warfare. The additional suggestion of Christia that random or stochastic events can lead to unexpected conflict outcomes is also further extended in this paper. The inclusion in the model of terms describing concurrent rebel recruitment of civilians and state deployment of troops are then described. Examples are presented for various hypothetical cases. It is demonstrated that numerical simulation techniques have great potential for modelling civil war. The Christia approach is shown to provide an excellent basis from which numerical models of civil conflict can be built and from which the progress of a conflict can usefully be visualised graphically.

scholarly journals REVIEW OF CFD SIMULATION OF OXY-COAL COMBUSTION FOR ELETRICAL POWER GENERATION: OPPORTUNITIES AND CHALLENGES

2016 ◽  
Vol 15 (2) ◽  
pp. 76
Author(s):  
F. S. Nascimento ◽  
M. A. R. Nascimento ◽  
C. J. R. Coronado ◽  
L. O. Rodrigues ◽  
J. A. Carvalho Jr ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Coal Combustion ◽  
Cfd Simulation ◽  
Numerical Models ◽  
Cost Savings ◽  
Pollutant Emissions ◽  
Computational Time ◽  
Simulation Techniques ◽  
Reduction Of Co2 ◽  
Physical Phenomena

The oxy-combustion has generated significant interested for reduction of CO2 emission when the fossil fuel is coal, due to simplification on the separation process of CO2 from the flue gas, it can be more easily stored in reservoir. The CFD numerical simulation techniques in oxy-coal combustion has the potential to contribute to designers in cost savings and reduced computational time; Furthermore, such techniques also provide a robust tool for better understanding and description of the aerothermodynamics processes involved, as well as, aiding the design of most efficient furnaces. However, to obtain representative results of the physical phenomena, the numerical models employed by CFD needs to be suitable for oxy-coal combustion. So, the aim of the paper is to carry out a review of the recent models that are being used for turbulence, combustion and pollutant emissions. Moreover, it is shown a comparison of different results obtained in the numerical simulation of oxy-coal combustion among new models, existing models and experiments. The analysis of the models and experiments shows that the challenges that are still being faced to obtain better accuracy of numerical simulation results. Improvements in the models for oxy-coal combustion can be seen like potential opportunities to investigate and optimize the process that occur in the combustion.

Pro-government militias and civil war termination

2021 ◽  
pp. 073889422110484
Author(s):  
Chelsea Estancona ◽  
Lindsay Reid
Keyword(s):  
Civil War ◽  
Competing Risks ◽  
Civil Wars ◽  
Civil Conflict ◽  
War Termination ◽  
Conflict Termination ◽  
Conflict Outcomes ◽  
Robust Evidence

Why do governments choose to fund pro-government militias (PGMs) if doing so could extend costly civil conflict? While PGMs are active in a majority of civil wars, their impact on conflict termination remains poorly understood. We argue that the choice to fund PGMs is a strategic one for states and part of their efforts to influence wartime dynamics and conflict termination. We hypothesize that PGMs’ impact on conflict termination is conditional on whether they are government funded. Government-funded PGMs help states to ward off costly negotiations and encourage the rebellion's gradual dissolution. Using competing risks analyses on civil wars ending between 1981 and 2007, we find robust evidence that PGM funding affects conflict outcomes.

scholarly journals Female combatants, forced recruitment, and civil conflict outcomes

2018 ◽  
Vol 5 (2) ◽  
pp. 205316801877055 ◽  
Author(s):  
Alex Braithwaite ◽  
Luna B. Ruiz
Keyword(s):  
Civil Wars ◽  
Regression Models ◽  
Multinomial Logistic Regression ◽  
Civil Conflict ◽  
Female Participation ◽  
Logistic Regression Models ◽  
Civil Conflicts ◽  
Rebel Groups ◽  
The Government ◽  
Conflict Outcomes

Women participated as combatants in almost 40% of civil conflicts that occurred between 1979 and 2009. We offer a novel argument about the effect of female combatants upon the outcomes of the civil conflicts that they join. Groups that recruit female combatants are more likely to achieve victory in their conflicts than are groups that do not recruit female combatants. However, when rebel groups rely upon forced recruitment, they risk undermining the benefits associated with female combatants, lowering their likelihood of victory relative to that of the government. We test this conditional argument using multinomial logistic regression models on a sample of 194 rebel groups globally from 1979 to 2009. We find that female participation appears to decrease the likelihood of government victory in civil wars; this effect holds primarily in instances in which female participation could plausibly be thought of as voluntary. Forced female participation, by contrast, appears to increase the likelihood of a government victory.

Simulation and Modeling of Turbulent Flows

1996 ◽  
Keyword(s):  
Numerical Simulation ◽  
Turbulent Flow ◽  
Turbulent Flows ◽  
Simulation And Modeling ◽  
Simulation Techniques ◽  
Rational Development ◽  
Group Methods ◽  
Turbulent Closure ◽  
The Subject ◽  
Renormalization Group Methods

This book provides students and researchers in fluid engineering with an up-to-date overview of turbulent flow research in the areas of simulation and modeling. A key element of the book is the systematic, rational development of turbulence closure models and related aspects of modern turbulent flow theory and prediction. Starting with a review of the spectral dynamics of homogenous and inhomogeneous turbulent flows, succeeding chapters deal with numerical simulation techniques, renormalization group methods and turbulent closure modeling. Each chapter is authored by recognized leaders in their respective fields, and each provides a thorough and cohesive treatment of the subject.

scholarly journals Symptoms of PTSD in Frontline Journalists: A Retrospective Examination of 18 Years of War and Conflict

2018 ◽  
Vol 63 (9) ◽  
pp. 629-635 ◽  
Author(s):  
Anthony Feinstein ◽  
Jonas Osmann ◽  
Viral Patel
Keyword(s):  
New York ◽  
Civil Wars ◽  
Ptsd Symptoms ◽  
Impact Of Event Scale ◽  
Event Scale ◽  
The Balkans ◽  
War And Conflict ◽  
The Mean ◽  
Migration Crisis ◽  
Election Violence

Objective: The objective of the current study was to determine the frequency and severity of symptoms of posttraumatic stress disorder (PTSD) in journalists covering conflict. Methods: PTSD data (Impact of Event Scale–Revised) collected over an 18-year period from 684 conflict journalists were analyzed retrospectively for frequency and severity of reexperiencing, avoidance, and arousal symptoms. Conflicts covered were civil wars in the Balkans ( n = 140 journalists), 9/11 attack in New York City ( n = 46), Iraq war ( n = 84), Mexico drug wars ( n = 104), civil war in Syria ( n = 59), Kenya election violence/Al-Shabab terror ( n = 57), state-sanctioned media intimidation in Iran ( n = 114), and the current migration crisis in Europe ( n = 80). Results: The mean age of the sample was 38.59 (SD = 8.35) years, 461 (67%) journalists were men, and the mean duration of conflict work was 13.42 (SD = 7.74) years. The 5 most frequently endorsed symptoms were in the reexperiencing/intrusion category. Mean intrusion (1.31, SD = 0.97), avoidance (1.08, SD = 0.89), and arousal (1.07, SD = 0.96) scores for the entire sample were in the mild range. Being female and less educated independently predicted PTSD symptoms. Conclusions: PTSD phenomenology in a group of conflict journalists with well over a decade of frontline experience is dominated by reexperiencing symptoms. While symptom severity is for the most part mild, group means can obscure those individuals with significantly more severe difficulties.

Experimental and numerical simulation of thermomechanical phenomena during a TIG welding process

2004 ◽  
Vol 120 ◽  
pp. 697-704
Author(s):  
L. Depradeux ◽  
J.-F. Jullien
Keyword(s):  
Numerical Simulation ◽  
Numerical Models ◽  
Welding Process ◽  
Central Zone ◽  
Mechanical Analysis ◽  
Tig Welding ◽  
General Ability ◽  
Reduced Dimensions ◽  
Simple Geometry ◽  
A Tig Welding

In this study, a parallel experimental and numerical simulation of phenomena that take place in the Heat Affected Zone during TIG welding on 316L stainless steel is presented. The aim of this study is to predict by numerical simulation residual stresses and distortions generated by the welding process. For the experiment, a very simple geometry with reduced dimensions is considered: the specimens are disks, made of 316L. The discs are heated in the central zone in order to reproduce thermo-mechanical cycles that take place in the HAZ during a TIG welding process. During and after thermal cycle, a large quantity of measurement is provided, and allows to compare the results of different numerical models used in the simulations. The comparative thermal and mechanical analysis allows to assess the general ability of the numerical models to describe the structural behavior. The importance of the heat input rate and material characteristics is also investigated.

scholarly journals Coup-Proofing and Civil War

2016 ◽  
Author(s):  
Jun Koga Sudduth
Keyword(s):  
Civil War ◽  
Civil Wars ◽  
Civil Conflict ◽  
The Other ◽  
Civil Military Relations ◽  
Rebel Groups ◽  
The Future ◽  
Face Threats ◽  
Military Relations ◽  
The Military

Political leaders face threats to their power from within and outside the regime. Leaders can be removed via a coup d’état undertaken by militaries that are part of the state apparatus. At the same time, leaders can lose power when they confront excluded opposition groups in civil wars. The difficulty for leaders, though, is that efforts to address one threat might leave them vulnerable to the other threat due to the role of the military as an institution of violence capable of exercising coercive power. On one hand, leaders need to protect their regimes from rebels by maintaining strong militaries. Yet, militaries that are strong enough to prevail against rebel forces are also strong enough to execute a coup successfully. On the other hand, leaders who cope with coup threats by weakening their militaries’ capabilities to organize a coup also diminish the very capabilities that they need to defeat their rebel challengers. This unfortunate trade-off between protection by the military and protection from the military has been the long-standing theme in studies of civil-military relations and coup-proofing. Though most research on this subject has focused primarily on rulers’ maneuvers to balance the threats posed by the military and the threats coming from foreign adversaries, more recent scholarship has begun to explore how leaders’ efforts to cope with coup threats will influence the regime’s abilities to address the domestic threats coming from rebel groups, and vice versa. This new wave of research focuses on two related vectors. First, scholars address whether leaders who pursue coup-proofing strategies that weaken their militaries’ capabilities also increase the regime’s vulnerability to rebel threats and the future probability of civil war. Second, scholars examine how the magnitude of threats posed by rebel groups will determine leaders’ strategies toward the militaries, and how these strategies affect both the militaries’ influence over government policy and the future probability of coup onsets. These lines of research contribute to the conflict literature by examining the causal mechanisms through which civil conflict influences coup propensity and vice versa. The literatures on civil war and coups have developed independently without much consideration of each other, and systematic analyses of the linkage between them have only just began.

A Comparison of Self-Rectifying Turbines for OWC Based Wave Energy Power Extracting Device Using Numerical Simulation

2002 ◽  
Author(s):  
A. R. Ansari ◽  
H. B. Khaleeq ◽  
A. Thakker
Keyword(s):  
Numerical Simulation ◽  
Wave Energy ◽  
Sea Water ◽  
Time History ◽  
Flow Conditions ◽  
Wells Turbine ◽  
Impulse Turbine ◽  
Simulation Techniques ◽  
Simple Geometry ◽  
Wide Range

This paper presents a comparison of self-rectifying turbines for the Oscillating Water Column (OWC) based Wave Energy power extracting device using numerical simulation. The two most commonly used turbines for OWC based devices, the Impulse and the Wells turbines were evaluated under real sea simulated conditions. Assuming the quasi-steady condition, experimental data for both 0.6m turbines with 0.6 hub to tip ratio was used to predict their behavior under real sea conditions. The real sea water surface elevation time history data was used to simulate the flow conditions using standard numerical simulation techniques. A simple geometry of the OWC was considered for the simulation. The results show that the overall mean performance of an Impulse turbine is better than the Wells turbine under unsteady, irregular real sea conditions. The Impulse turbine was observed to be more stable over a wide range of flow conditions. This paper reports the comparison of performance characteristics of both these turbines under simulated real sea conditions.

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