scholarly journals Wildland surface fire spread modelling, 1990 - 2007. 3: Simulation and mathematical analogue models

2009 ◽  
Vol 18 (4) ◽  
pp. 387 ◽  
Author(s):  
Andrew L. Sullivan
Keyword(s):  
Physical Nature ◽  
Simulation Models ◽  
Mathematical Concept ◽  
Fire Spread ◽  
Two Dimensions ◽  
Computational Power ◽  
Surface Fire ◽  
One Dimensional ◽  
Analogue Models ◽  
Physical Representation

In recent years, advances in computational power have led to an increase in attempts to model the behaviour of wildland fires and to simulate their spread across landscape. The present series of articles endeavours to comprehensively survey and précis all types of surface fire spread models developed during the period 1990–2007. The present paper surveys models of a simulation or mathematical analogue nature. Most simulation models are implementations of existing empirical or quasi-empirical models and their primary function is to convert these generally one-dimensional models to two dimensions and then simulate the propagation of a fire perimeter across a modelled landscape. Mathematical analogue models are those that are based on some mathematical concept (rather than a physical representation of fire spread) that coincidentally represents the spread of fire. Other papers in the series survey models of a physical or quasi-physical nature, and empirical or quasi-empirical nature. Many models are extensions or refinements of models developed before 1990. Where this is the case, these models are also discussed but much less comprehensively.

scholarly journals Wildland surface fire spread modelling, 1990 - 2007. 1: Physical and quasi-physical models

2009 ◽  
Vol 18 (4) ◽  
pp. 349 ◽  
Author(s):  
Andrew L. Sullivan
Keyword(s):  
Physical Nature ◽  
Simulation Models ◽  
Fire Spread ◽  
Physical Models ◽  
Current Paper ◽  
Present Series ◽  
Wildland Fires ◽  
Computational Power ◽  
Surface Fire ◽  
Starting Point

In recent years, advances in computational power have led to an increase in attempts to model the behaviour of wildland fires and to simulate their spread across the landscape. The present series of articles endeavours to comprehensively survey and précis all types of surface fire spread models developed during the period 1990–2007, providing a useful starting point for those readers interested in recent modelling activities. The current paper surveys models of a physical or quasi-physical nature. These models are based on the fundamental chemistry and physics, or physics alone, of combustion and fire spread. Other papers in the series review models of an empirical or quasi-empirical nature, and mathematical analogues and simulation models. Many models are extensions or refinements of models developed before 1990. Where this is the case, these models are also discussed but in much less detail.

scholarly journals Wildland surface fire spread modelling, 1990 - 2007. 2: Empirical and quasi-empirical models

2009 ◽  
Vol 18 (4) ◽  
pp. 369 ◽  
Author(s):  
Andrew L. Sullivan
Keyword(s):  
Statistical Analysis ◽  
Wind Speed ◽  
Physical Nature ◽  
Simulation Models ◽  
Fire Spread ◽  
Empirical Models ◽  
Fuel Moisture ◽  
Computational Power ◽  
Surface Fire ◽  
Fuel Moisture Content

In recent years, advances in computational power have led to an increase in attempts to model the behaviour of wildland fires and to simulate their spread across landscape. The present series of articles endeavours to comprehensively survey and précis all types of surface fire spread models developed during the period 1990–2007. The current paper surveys models of an empirical or quasi-empirical nature. These models are based on the statistical analysis of experimentally obtained data with or without some physical framework for the basis of the relations. Other papers in the series review models of a physical or quasi-physical nature, and mathematical analogues and simulation models. The main relations of empirical models are those of wind speed and fuel moisture content with rate of forward spread. The focus of the discussion is on the treatment of the wind speed and fuel moisture functions by the models.

RATES OF SURFACE FIRE SPREAD IN A YOUNG CALABRIAN PINE (Pinus brutia Ten.) PLANTATION

2012 ◽  
Vol 11 (8) ◽  
pp. 1475-1480 ◽  
Author(s):  
Omer Kucuk ◽  
Ertugrul Bilgili ◽  
Serkan Bulut ◽  
Paulo M. Fernandes
Keyword(s):  
Fire Spread ◽  
Surface Fire ◽  
Pinus Brutia ◽  
Calabrian Pine

scholarly journals Assessing a Linear Nanosystem's Limiting Reliability from its Components

2008 ◽  
Vol 45 (03) ◽  
pp. 879-887 ◽  
Author(s):  
Nader Ebrahimi
Keyword(s):  
Present State ◽  
Size Range ◽  
Two Dimensions ◽  
The Other ◽  
One Dimension ◽  
Present Moment ◽  
One Dimensional ◽  
The One ◽  
Fixed Moment ◽  
Nanosized Systems

Nanosystems are devices that are in the size range of a billionth of a meter (1 x 10-9) and therefore are built necessarily from individual atoms. The one-dimensional nanosystems or linear nanosystems cover all the nanosized systems which possess one dimension that exceeds the other two dimensions, i.e. extension over one dimension is predominant over the other two dimensions. Here only two of the dimensions have to be on the nanoscale (less than 100 nanometers). In this paper we consider the structural relationship between a linear nanosystem and its atoms acting as components of the nanosystem. Using such information, we then assess the nanosystem's limiting reliability which is, of course, probabilistic in nature. We consider the linear nanosystem at a fixed moment of time, say the present moment, and we assume that the present state of the linear nanosystem depends only on the present states of its atoms.

PERFORMANCE LIMITS OF SIMULATION MODELS FOR NOISE CHARACTERIZATION OF MM WAVE DEVICES

2007 ◽  
Vol 07 (03) ◽  
pp. L299-L312
Author(s):  
ALI ABOU-ELNOUR
Keyword(s):  
Boltzmann Transport Equation ◽  
Simulation Models ◽  
Two Dimensions ◽  
Boltzmann Transport ◽  
Performance Limits ◽  
Drift Diffusion ◽  
Model Equations ◽  
Accuracy Of Results ◽  
Noise Characterization

Based on Boltzmann transport equation, the drift-diffusion, hydrodynamic, and Monte-Carlo physical simulators are accurately developed. For each simulator, the model equations are self-consistently solved with Poisson equation, and with Schrödinger equation when quantization effects take place, in one and two-dimensions to characterize the operation and optimize the structure of mm-wave devices. The effects of the device dimensions, biasing conditions, and operating frequencies on the accuracy of results obtained from the simulators are thoroughly investigated. Based on physical understanding of the models, the simulation results are analyzed to fully determine the limits at which a certain device simulator can be accurately and efficiently used to characterize the noise behavior of mm-wave devices.

The simulation of surface fire spread based on Rothermel model in windthrow area of Changbai Mountain (Jilin, China)

2018 ◽  
Author(s):  
Hang Yin ◽  
Hui Jin ◽  
Ying Zhao ◽  
Yuguang Fan ◽  
Liwu Qin ◽  
...  
Keyword(s):  
Fire Spread ◽  
Changbai Mountain ◽  
Surface Fire

The Structure of Emotional Response: 1984 Presidential Candidates

1988 ◽  
Vol 82 (3) ◽  
pp. 737-761 ◽  
Author(s):  
George E. Marcus
Keyword(s):  
Emotional Response ◽  
Two Dimensions ◽  
Negative Emotionality ◽  
One Dimensional ◽  
Presidential Candidates ◽  
The Past ◽  
Emotional Appraisal ◽  
Psychological Models ◽  
Dimensional Models ◽  
Feeling Thermometer

Over the past two decades psychological models of affect have changed from valence (one-dimensional) models to multiple-dimensional models. The most recent models, circumplex models, are two-dimensional. Feeling thermometer measures, which derive their theoretical logic from earlier (valence) models of emotional appraisal, are shown to be confounded. Underlying the variation obtained using feeling thermometer measures are two dimensions of emotional response, mastery (positive emotionality) and threat (negative emotionality). Analysis of the 1984 NES survey suggests that positive emotional response is twice as influential as negative emotional response in predicting presidential candidate vote disposition to the presidential candidates. Reliance on emotional response is shown to be uniformly influential across various strata of the electorate.Policy considerations have little direct influence on vote disposition, though policy considerations are indirectly related to vote disposition through the influence of issues on the degree of feelings of threat evoked by the candidates.

scholarly journals THE EFFECT OF THE THIRD DIMENSION ON ROUGH SURFACES FORMED BY SEDIMENTING PARTICLES IN QUASI-TWO-DIMENSIONS

2002 ◽  
Vol 16 (08) ◽  
pp. 1217-1223 ◽  
Author(s):  
K. V. MCCLOUD ◽  
M. L. KURNAZ
Keyword(s):  
Two Dimensions ◽  
Scaling Analysis ◽  
Silica Spheres ◽  
Two Dimensional ◽  
One Dimensional ◽  
The Third ◽  
Roughness Exponent ◽  
Third Dimension ◽  
Dimensional Cell ◽  
Roughness Exponents

The roughness exponent of surfaces obtained by dispersing silica spheres into a quasi-two-dimensional cell is examined. The cell consists of two glass plates separated by a gap, which is comparable in size to the diameter of the beads. Previous work has shown that the quasi-one-dimensional surfaces formed have two roughness exponents in two length scales, which have a crossover length about 1 cm. We have studied the effect of changing the gap between the plates to a limit of about twice the diameter of the beads. If the conventional scaling analysis is performed, the roughness exponent is found to be robust against changes in the gap between the plates; however, the possibility that scaling does not hold should be taken seriously.

An Instrument for One- or Two-Dimensional Tracking

1965 ◽  
Vol 21 (1) ◽  
pp. 307-312
Author(s):  
William C. Roehrig
Keyword(s):  
Low Cost ◽  
Two Dimensions ◽  
Two Dimensional ◽  
Error Signal ◽  
One Dimensional ◽  
Constant Torque ◽  
Sinusoidal Motion ◽  
The Cross ◽  
Target Path

A rugged electro-mechanical tracking apparatus of simple, low-cost construction is described. The apparatus can be used for one-dimensional tracking by connecting only the longitudinal motor, thus forcing the target to move back and forth in either simple sinusoidal motion or according to the sum of two or three sinusoids. The relative phases of the three sinusoids can be rapidly altered, as can the amplitudes (within limits) of each of the sinusoids. The frequency of the sinusoids can be changed either independently or conjointly. By also connecting the cross-feed motor, an essentially unpredictable target path in two dimensions is obtained, and this path can be rapidly altered by changing cams, and/or frequency, amplitude, and phase of the sinusoids. Movement of the cursor is by low, constant torque lathe-type controls. The distance the cursor moves per each rotation of the controls, can be altered for either or both of the controls. A continuous error signal is generated which is directly proportional to the distance the cursor is off target in any direction.

Differences in the Heat Transfer at the Core-Reflector Boundary of the PBMR Due to the Use of Different Numerical Methods

2009 ◽  
Author(s):  
Pieter S. du Toit ◽  
Onno Ubbink
Keyword(s):  
Two Dimensions ◽  
Heat Sources ◽  
Coarse Mesh ◽  
One Dimensional ◽  
Root Cause ◽  
The Core ◽  
Modified Method ◽  
The Difference ◽  
Horizontal Slice ◽  
Mesh Cell

The PBMR (Pebble Bed Modular Reactor) is a High-Temperature Gas-cooled Reactor (HTGR) concept. One of the exercises of the PBMR benchmark of the Organization for Economic Cooperation and Development (OECD) is a steady state two-dimensional (2D) thermal-hydraulics simulation of a simplified PBMR with prescribed heat sources. Two different programs were used to model this exercise. They predicted similar core temperatures but the side reflector temperatures next to the core differed by more than 30 °C (when using a relatively coarse mesh). The underlying methods define temperatures at either vertices (VC) or at mesh cell centres (CC). A study was undertaken using one-dimensional (1D) implementations of the VC and CC methods to model a horizontal slice through the core. This study revealed the root cause of the different predictions. A modified version of the 1D CC method was developed that essentially predicts the same temperatures as the VC method. The extension of the modified method to two dimensions is under investigation. If the difference in predicted temperatures next to the core can be eliminated or reduced, then the focus can shift to other differences between the results of the two programs.

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