Surface-source modeling and estimation using biomagnetic measurements

We propose a number of electric source models that are spatially distributed on an unknown surface for biomagnetism. These can be useful to model, e.g., patches of electrical activity on the cortex. We use a realistic head (or another organ) model and discuss the special case of a spherical head model with radial sensors resulting in more efficient computations of the estimates for magnetoencephalography. We derive forward solutions, maximum likelihood (ML) estimates, and Cramér-Rao bound (CRB) expressions for the unknown source parameters. A model selection method is applied to decide on the most appropriate model. We also present numerical examples to compare the performances and computational costs of the different models and illustrate when it is possible to distinguish between surface and focal sources or line sources. Finally, we apply our methods to real biomagnetic data of phantom human torso and demonstrate the applicability of them.     

Room temperature creep of Ti-6AI-4V

Recent investigations have shown both that Ti-6A1-4V does and does not exhibit room temperature creep at low stress. In the present investigation three different microstructures (α β anneal, recrystallization anneal and β anneal) of Ti-6A1-4V were examined under dead weight torsional loading. The loading sequence was forward, reverse and second forward loading. It was concluded that even at a stress level well below the yield stress the alloy exhibits creep in forward loading and increased creep strain in reverse loading and second forward loading. Furthermore the rate of creep at constant stress was different in different microstructures of the alloy; the maximum creep rate occurred with the recrystallization anneal and the minimum creep rate occurred with the β anneal. At the maximum stress in forward loading there appeared to be a change in creep mechanism.     

Evaluation of the impact of the surrounding urban morphology on building energy consumption

Empirical models of minimum (T_min), average (T_avg) and maximum (T_max) air temperature for Singapore estate have been developed and validated based on a long-tem field measurement. There are three major urban elements, which influence the urban temperature at the local scale. Essentially, they are buildings, greenery and pavement. Other related parameters identified for the study, such as green plot ratio (GnPR), sky view factor (SVF), surrounding building density, the wall surface area, pavement area, albedo are also evaluated to give a better understanding on the likely impact of the modified urban morphology on energy consumption.The objective of this research is to assess and to compare how the air temperature variation of urban condition can affect the building energy consumption in tropical climate of Singapore. In order to achieve this goal, a series of numerical calculation and building simulation are utilized. A total of 32 cases, considering different urban morphologies, are identified and evaluated to give better a understanding on the implication of urban forms, with the reference to the effect of varying density, height and greenery density. The results show that GnPR, which related to the present of greenery, have the most significant impact on the energy consumption by reducing the temperature by up to 2 °C. The results also strongly indicate an energy saving of 4.5% if the urban elements are addressed effectively.     

An improved elman neural network controller based on quasi‐ARX neural network for nonlinear systems

An improved Elman neural network (IENN) controller with particle swarm optimization (PSO) is presented for nonlinear systems. The proposed controller is composed of a quasi‐ARX neural network (QARXNN) prediction model and a switching mechanism. The switching mechanism is used to guarantee that the prediction model works well. The primary controller is designed based on IENN using the backpropagation (BP) learning algorithm with PSO. PSO is used to adjust the learning rates in the BP process for improving the learning capability. The adaptive learning rates of the controller are investigated via the Lyapunov stability theorem. The proposed controller performance is verified through numerical simulation. The method is compared with the fuzzy switching and 0/1 switching methods to show its effectiveness in terms of stability, accuracy, and robustness. © 2014 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Computational intelligence for heart disease diagnosis: A medical knowledge driven approach

This paper investigates a number of computational intelligence techniques in the detection of heart disease. Particularly, comparison of six well known classifiers for the well used Cleveland data is performed. Further, this paper highlights the potential of an expert judgment based (i.e., medical knowledge driven) feature selection process (termed as MFS), and compare against the generally employed computational intelligence based feature selection mechanism. Also, this article recognizes that the publicly available Cleveland data becomes imbalanced when considering binary classification. Performance of classifiers, and also the potential of MFS are investigated considering this imbalanced data issue. The experimental results demonstrate that the use of MFS noticeably improved the performance, especially in terms of accuracy, for most of the classifiers considered and for majority of the datasets (generated by converting the Cleveland dataset for binary classification). MFS combined with the computerized feature selection process (CFS) has also been investigated and showed encouraging results particularly for NaiveBayes, IBK and SMO. In summary, the medical knowledge based feature selection method has shown promise for use in heart disease diagnostics.     

Paper Making from Banana Pseudo-Stem: Characterization and Comparison

This study deals with the determination of paper-making potentialities of banana pseudo-stems growing in Thailand. Chlorine dioxide (D_o and D₁) and extraction (E_p) treatments were all performed in sealed plastic bags in a thermostatically controlled water bath. Unbleached banana kraft pulp in the kappa number range of 23–28 was not easy to bleach with three-stage sequence of D₀-E_P-D₁. The determination of mechanical properties of standard paper after mild beating in the laboratory is discussed as is the interpretation of the results. As an indication of potential paper-making properties, they are important for the pulp producer in the control of fiber characteristics. The brightness was achieved at 45% ISO, with a viscosity level at 585 mL/g. Drainage of pulp was extremely slow and paper-making properties were characterized by low strength, low bulk, rough surface, and extremely poor optical properties.     

The transthoracic impedance cardiogram is a potential haemodynamic sensor for an automated external defibrillator

AIMS: The American Heart Association has endorsed the concept of Public Access Defibrillation. However, there have been reports of inappropriate direct current shocks from automatic external defibrillators. The specificity of automatic external defibrillators for shockable rhythms may be improved by the incorporation of a haemodynamic sensor. METHODS AND RESULTS: This study examined the use of four parameters extracted from the impedance cardiogram i.e. Peak dz/dt (the peak of the impedance cardiogram measured from the line dz/dt=0 ohms(-1)), Peak-trough (the peak-to-trough measurement of the impedance cardiogram ohms(-1)), Area 1 (the area under the C wave of the impedance cardiogram above the line dz/dt=0 mohm) and Area 2 (the area under the impedance cardiogram 50 ms on either side of the Peak and above the line dz/dt=0 mohm) as predictors of cardiac output. At 116 cardiac arrest calls the ECG and impedance cardiogram were recorded through two ECG/defibrillator pads placed in an antero-apical position. Nine recordings were rejected for artefact. The rhythm recorded in the remaining 107 calls was asystole (19), ventricular fibrillation (14), agonal rhythm (20), electromechanical dissociation (22), ventricular tachycardia (27) and sinus rhythm (5). These rhythms were divided into those associated with haemodynamic collapse i.e. no pulse -- asystole, ventricular fibrillation, agonal rhythm, electromechanical dissociation and shockable ventricular tachycardia (associated with loss of consciousness, pulselessness or a systolic blood pressure of <80 mmHg) (Group 1) and those associated with a satisfactory cardiac output i.e. non-shockable ventricular tachycardia (conscious with a pulse) and sinus rhythm (Group 2). On univariate analysis each of the four impedance cardiogram parameters were significantly greater in Group 2 than Group 1 (P<0.001). On multivariate analysis the parameters which best differentiated the two groups were Area 1 and Peak-trough. CONCLUSION: Thus the impedance cardiogram is a potential haemodynamic sensor for an automatic external defibrillator.