Simple Simulation System Research Articles

Simulation of stand dynamics for miombo woodlands in Kitulangalo Forest Reserve, Morogoro, Tanzania

ABSTRACT Miombo woodlands constitute the most extensive type of forest cover within South and East Africa, Tanzania in particular, and they are seriously threatened by intensive degradation and deforestation. The dynamics of miombo stands were examined in this study using a simple simulation system applied to experimental stands at the Kitulangalo Forest Reserve (KFR) in Tanzania. Prediction of tree-level diameter increment, mortality, and ingrowth across species groups with empirical models based on data from experimental sites constituted the essential elements of the simulation system. Diameter distribution, stand basal area, volume yield, and above-ground biomass accumulation were assessed in three harvesting alternatives across three species groups. The results indicate a high degree of positive response to careful selective harvesting in lightly degraded, recovering miombo forests. Simulation systems compiled from experimentally based models seem promising as tools for research on stand dynamics and sustainable management alternatives in miombo woodlands.

A Simple Simulation System for Quantifying Buttock Loads Caused by Daily Activities of Wheelchair Users.

The purpose of this study is to quantify the load generated on the buttocks during wheelchair operation in order to clarify the cause of pressure injuries on the buttocks of wheelchair users. In the case of repeated measurements, pressure injuries may occur by conducting experiments with people with actual disabilities. In this study, we proposed a method of dynamic simulation using a humanoid model in order to carry out buttock load safely due to exercise. In addition, the load on the buttocks is quantified by reproducing a simulated cushion that reproduces the actual physical properties on the simulator. When we conducted an evaluation experiment of the developed simulation to quantify the buttock load, we confirmed the validity of this simulator in the front-back direction. On the other hand, the correlation with the actual data is low in the left-right direction, and it is considered necessary to improve the humanoid model in order to improve the accuracy.

A novel process monitoring and fault detection approach based on statistics locality preserving projections

Data-driven fault detection technique has exhibited its wide applications in industrial process monitoring. However, how to extract the local and non-Gaussian features effectively is still an open problem. In this paper, statistics locality preserving projections (SLPP) is proposed to extract the local and non-Gaussian features. Firstly, statistics pattern analysis (SPA) is applied to construct process statistics and grasp the non-Gaussian statistical property using high order statistics. Then, locality preserving projections (LPP) method is used to discover local manifold structure of the statistics. In essence, LPP tries to map the close points in the original space to close in the low-dimensional space. Lastly, T2 and squared prediction error (SPE) charts of SLPP model are used to detect process faults. One simple simulated system and the Tennessee Eastman process show that the proposed SLPP method is more effective than principal component analysis, LPP and statistics principal component analysis in fault detection performance.

The Perceived Benefits of Video-based Simulation for People who Stutter

The use of virtual worlds and video games offer exciting new avenues for the treatment of communication disorders and ongoing client support. But these new avenues need time to be envisaged, developed and rigorously evaluated. Also, perhaps the potential users themselves of such systems will need additional time to become comfortable and able to interact efficiently with them. Conceivably during this era of rapid technological advancements some basic virtual systems could be more swiftly introduced and trialled in order to complement existing therapy and support methods. A video-based simulation platform called Scenari-Aid fits this criterion. The aim of this study was to survey the perceptions of people who stutter who had used Scenari-Aid to assist them with their fluency and related anxieties. Could a simple, and relatively cheap to develop, simulation system have perceived benefits for a person who stutters and could these perceived benefits be translated beyond their practice environment? Over a six month period starting in late 2011, a 54 question online survey was made avail able to people who stutter and who were members of Speak Easy Australia and the McGuire Programme (Australia). To be eligible for the study you had to be over 18, have worked through a majority of the scenarios that were included in the Scenari-Aid application and have given the application more than one single attempt. It was assumed that most of the respondents would have been actively using a fluency shaping technique of some form during that time period. Questions were themed in terms of product quality, perceptions of fluency, value to therapy, effect on anxiety and product worth. Overall 37 completed responses were gathered and analysed using descriptive statistics.The results of this study were very encouraging in terms of the perceived effects that a simple simulation system could offer a person who stutters. Broadly speaking a majority of the users of Scenari-Aid found the system intuitive to use and understand. The most encouraging results stemmed from respondent's perception of their fluency and anxiety. Users indicated that by using this simple system that they felt their levels of fluency and speech confidence increasing. In terms of anxiety a majority of the users indicated that the system helped to ease anxieties related to speaking in public. Importantly though a majority of the users indicated that the system assisted them to better manage their speech and aided with self-critiquing speech progress.The results of this study indicate that there are perceived benefits for people who stutter to use video-based simulations to assist them with overall levels of fluency and social speaking confidence. The study also indicates that such a system could perhaps compliment conventional speech therapy and related support systems. More research is now required to investigate beyond user perceptions and to evaluate if indeed a simple video-based simulation system has real positive effects on rates of fluency, levels of anxiety and worth to conventional therapy techniques.

Discrete-time extremum-seeking for Wiener–Hammerstein plants

This paper presents a new formulation of extremum-seeking control for discrete-time Wiener–Hammerstein plants. A novel method of analysis using Linear Parameter-Varying (LPV) system theory demonstrates semi-global stability of the control scheme. Assuming only limited plant knowledge, the stability result ensures convergence of the plant output in steady state to a point in an arbitrarily small neighbourhood of the extremum, for appropriately chosen controller parameters. The behaviour of the control scheme is analysed on a simple simulated system, prior to being implemented on an internal combustion engine. Experiments demonstrate how the scheme is able to maximise engine output torque in the presence of an uncertain fuel composition by modifying the spark timing.

PWA DYNAMIC IDENTIFICATION FOR NONLINEAR MODEL FAULT DETECTION

This paper addresses the identification of non–linear dynamic systems. A wide class of these systems can be described using non–linear time-invariant regression models, that can be approximated by means of piecewise affine prototypes with an arbitrary degree of accuracy. This work concerns the identification of piecewise affine model structure through input-output data acquired from a dynamic process. In order to show the effectiveness of the developed technique, when exploited also for FDI purpose, the results obtained in the identification of both a simple simulated system and a real dynamic process are reported.

APPROXIMATION OF NON—LINEAR SYSTEMS WITH IDENTIFIED HYBRID MODELS

This paper addresses the identification of non-linear dynamic systems. A wide class of these systems can be described using non-linear time-invariant regression models, that can be approximated by means of piecewise affine prototypes with an arbitrary degree of accuracy. This work concerns the identification of piecewise affine model structure through input-output data acquired from a dynamic process. In order to show the effectiveness of the developed technique, the results obtained in the identification of both a simple simulated system and a real dynamic process are reported.

Parameter Identification of Piecewise Affine Dynamic Models from Input–Output Data

This paper addresses the identification of non-linear dynamic systems. A wide class of these systems can be described using non-linear time-invariant regression models, that can be approximated by means of piecewise affine prototypes with an arbitrary degree of accuracy. This work concerns the identification of piecewise affine model structure through input-output data acquired from a dynamic process. In order to show the effectiveness of the developed technique, the results obtained in the identification of both a simple simulated system and a real dynamic process are reported.

Effects of Traffic Information on Driver's Judgment of Curve Sharpness

The effects of information on a driver's judgment of curve sharpness were investigated by he personal computer simulation system. Three kinds of traffic sign and three kinds of voice guidance system were proposed to inform curve depth accurately. Six curve sections were picked up for sharpness assessment. Both a sign and a voice guidance pattem were superimposed on the driving scene using Adobe premiere 6.0. The 289 subjects estimated the sharpness subjectively. They saw six different curve patterns displayed on the computer screen. Also, they selected one cue among four cues as the most imporant cue for judging curve sharpness. Scatter plots of pre-judgment scores vs. post-judgment scores are used to analyze the effects of information on sharpness judgment. As a result, the adequate information indicated a positive effect on sharpness estimatin. The video scene was the largest factor for sharpness estimation. The effects of proposed traffic sign were larger than those of the voice guidance system. In addition, sharpness judgment at the left curve was more sensitive than that at the right curve. It should be noted that post-judgment score did not varied widely by pre-judgment scores. There are certain limitations to using the simple simulation system.

Simulation of coal pyrolysis in plasma jet by CPD model

Data-driven fault detection technique has exhibited its wide applications in industrial process monitoring. However, how to extract the local and non-Gaussian features effectively is still an open problem. In this paper, statistics locality preserving projections (SLPP) is proposed to extract the local and non-Gaussian features. Firstly, statistics pattern analysis (SPA) is applied to construct process statistics and grasp the non-Gaussian statistical property using high order statistics. Then, locality preserving projections (LPP) method is used to discover local manifold structure of the statistics. In essence, LPP tries to map the close points in the original space to close in the low-dimensional space. Lastly, T2 and squared prediction error (SPE) charts of SLPP model are used to detect process faults. One simple simulated system and the Tennessee Eastman process show that the proposed SLPP method is more effective than principal component analysis, LPP and statistics principal component analysis in fault detection performance.

Identification of piecewise affine models in noisy environment

This paper addresses the identification of non-linear systems. A wide class of these systems can be described using non-linear time-invariant regression models, that can be approximated by means of piecewise affine prototypes with an arbitrary degree of accuracy. This work concerns the identification of piecewise affine model parameters through input-output data affected by additive noise. In order to show the effectiveness of the developed technique, the results obtained in the identification of both a simple simulated system and a real dynamic process are reported.

A simple simulation method for river self-purification studies

A simple simulation system is described for the study of river self-purification processes. A linear relationship between the organic load and the critical deficit on the sag curve was obtained for each temperature, corresponding to 36–52 per cent assimilation. The rate is not constant, and the monomolecular theory is not suitable to describe the results. Two distinct phases are observed. Nitrification appears as a second and distinct sag in the oxygen curve. It is limited by oxygen transfer and equilibrates at an O 2 tension of 0·6–1·05 mg 1 −1.

SIMCON—simulation control to optimize man-machine interaction

The fitting of mathematical models to physiological systems can be tedious and difficult, whether one uses analog or digital computer methods. Both methods have their pros and cons depending on the available hardware and software and on the type of modeling. In recent years many digital simulation languages have been written combining analog-like and digital features to facilitate modeling, but, for a variety of reasons, none of these was suitable for our applications. We, therefore, designed a new digital simulation control system, SIMCON, which is described in this paper.The primary objectives were to provide: Maximum man-machine interaction at run-time, including visual displays, digital control, and both continuous analog and digital parameter adjustmentThe ability to generate solutions and to fit them to experimental data or other theoretical curves with a minimum of computer memoryThe option to use a mathematically oriented language, FORTRAN, and block operators with variable input/output.The result is a relatively general and simple simulation system which is easy to use and has wide versatility.