Model selection approaches for non-linear system identification: a review

The identification of non-linear systems using only observed finite datasets has become a mature research area over the last two decades. A class of linear-in-the-parameter models with universal approximation capabilities have been intensively studied and widely used due to the availability of many linear-learning algorithms and their inherent convergence conditions. This article presents a systematic overview of basic research on model selection approaches for linear-in-the-parameter models. One of the fundamental problems in non-linear system identification is to find the minimal model with the best model generalisation performance from observational data only. The important concepts in achieving good model generalisation used in various non-linear system-identification algorithms are first reviewed, including Bayesian parameter regularisation and models selective criteria based on the cross validation and experimental design. A significant advance in machine learning has been the development of the support vector machine as a means for identifying kernel models based on the structural risk minimisation principle. The developments on the convex optimisation-based model construction algorithms including the support vector regression algorithms are outlined. Input selection algorithms and on-line system identification algorithms are also included in this review. Finally, some industrial applications of non-linear models are discussed.     

Probabilistic classification of acute myocardial infarction from multiple cardiac markers

Logistic regression and Gaussian mixture model (GMM) classifiers have been trained to estimate the probability of acute myocardial infarction (AMI) in patients based upon the concentrations of a panel of cardiac markers. The panel consists of two new markers, fatty acid binding protein (FABP) and glycogen phosphorylase BB (GPBB), in addition to the traditional cardiac troponin I (cTnI), creatine kinase MB (CKMB) and myoglobin. The effect of using principal component analysis (PCA) and Fisher discriminant analysis (FDA) to preprocess the marker concentrations was also investigated. The need for classifiers to give an accurate estimate of the probability of AMI is argued and three categories of performance measure are described, namely discriminatory ability, sharpness, and reliability. Numerical performance measures for each category are given and applied. The optimum classifier, based solely upon the samples take on admission, was the logistic regression classifier using FDA preprocessing. This gave an accuracy of 0.85 (95% confidence interval: 0.78–0.91) and a normalised Brier score of 0.89. When samples at both admission and a further time, 1–6 h later, were included, the performance increased significantly, showing that logistic regression classifiers can indeed use the information from the five cardiac markers to accurately and reliably estimate the probability AMI.     

Social support as an individual difference variable: Its stability, origins, and relational aspects.

Investigated the stability of social support indices, the relation between these indices and measures of parental bonding, and the relation between the indices and ratings of social behavior. In Exp I, 76 undergraduates responded to a social support questionnaire (SSQ) several times at 5- and 36-mo follow-ups. Exp II partially replicated Exp I with 251 Ss, and it investigated the relation between the SSQ and a parental bonding instrument. In Exp III, 160 Ss rated videotapes of persons with different levels of social support and scored them with regard to indices of personal effectiveness. The studies demonstrate that social support levels are stable over periods up to 3 yrs. They also showed that Ss high in social support reported having received more parental care (affection, interest, empathy) than did those low in social support. High social support Ss were judged by observers to be more competent leaders and problem solvers than were low-support Ss. Female Ss were judged to be more considerate and friendly than male Ss. Results suggest the value of conceptualizing social support as an individual difference variable as well as an environmental provision. (29 ref) (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Temporal integration between visual images and visual percepts.

Using a temporal integration task, subjects in 5 experiments were expected to combine information from temporally separated visual presentations. Evidence from these experiments indicated that perceptual information can be integrated with previously generated and currently maintained visual images to form a representation that contains information from each source. Properties and limitations of this integration process were also explored, including the time required to generated the image, the speed at which percepts were integrated with images, and the capacity of the representation. Implications for theories of visual processing and memory are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Fast model-based feature matching technique applied to airport lighting

The use of image processing techniques to assess the performance of airport landing lighting using images of it collected from an aircraft-mounted camera is documented. In order to assess the performance of the lighting, it is necessary to uniquely identify each luminaire within an image and then track the luminaires through the entire sequence and store the relevant information for each luminaire, that is, the total number of pixels that each luminaire covers and the total grey level of these pixels. This pixel grey level can then be used for performance assessment. The authors propose a robust model-based (MB) feature-matching technique by which the performance is assessed. The development of this matching technique is the key to the automated performance assessment of airport lighting. The MB matching technique utilises projective geometry in addition to accurate template of the 3D model of a landing-lighting system. The template is projected onto the image data and an optimum match found, using nonlinear least-squares optimisation. The MB matching software is compared with standard feature extraction and tracking techniques known within the community, these being the Kanade-Lucus-Tomasi (KLT) and scale-invariant feature transform (SIFT) techniques. The new MB matching technique compares favourably with the SIFT and KLT feature-tracking alternatives. As such, it provides a solid foundation to achieve the central aim of this research which is to automatically assess the performance of airport lighting.     

SOME SHEET-IRON GROUND-COAT REBOIL AND BOND STUDIES USING SEVERAL ENAMELING STOCKS*

This paper presents results and observations obtained from a study of metals and some metallic oxides as mill additions to eliminate or reduce reboiling of ground-coat enamels.     

Information integration across eye movements.

The visual world contains more information than can be perceived in a single glance. Consequently, humans make eye and head movements and somehow construct a stable and continuous representation of the visual environment from these successive views. How this is accomplished has puzzled psychologists for over a century. The present research investigated the properties of transsaccadic integration, the integration of information across saccadic eye movements. The results of several experiments suggest that the mental representation of the environment that is constructed across eye movements is surprisingly schematic and undetailed, and based more on the contents of the current fixation than on one's memory for the contents of previous fixations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Systolic square root covariance Kalman filtering

The square root covariance Kalman filter (SRCF) and the square root covariance Kalman predictor (SRCP) are derived from a least squares viewpoint. A new systolic array architecture is presented which is suitable for implementing both forms of the filter. The systolic SRCF is found to be comparable with other architectures in the literature in terms of size, speed and processor utilization. The SRCP is faster than any comparable architecture withO(2n) timesteps between measurements.