An updated estimate of the body dimensions of US children

Anthropometric data from children are important for product design and the promulgation of safety standards. The last major detailed study of child anthropometry in the USA was conducted more than 30 years ago. Subsequent demographic changes and the increased prevalence of overweight and obesity render those data increasingly obsolete. A new, large-scale anthropometric survey is needed. As an interim step, a new anthropometric synthesis technique was used to create a virtual population of modern children, each described by 84 anthropometric measures. A subset of these data was validated against limited modern data. Comparisons with data from the 1970s showed significant changes in measures of width and circumference of the torso, arms and legs. Measures of length and measurements of the head, face, hands and feet exhibited little change. The new virtual population provides guidance for a comprehensive child anthropometry survey and could improve safety and accommodation in product design.

Practitioner Summary: This research reviews the inadequacies of available sources of US child anthropometry as a result of the rise in the rates of overweight and obesity. A new synthesised database of detailed modern child anthropometry was created and validated. The results quantify changes in US child body dimensions since the 1970s.     

An approach to averaging digitized plantagram curves

The averaging of outline shapes of the human foot for the purposes of determining information concerning foot shape and dimension within the context of comfort of fit of sport shoes is approached as a mathematical problem. An outline of the human footprint is obtained by standard procedures and the curvature is traced with a Hewlett Packard Digitizer. The paper describes the determination of an alignment axis, the identification of two ray centres and the division of the total curve into two overlapping arcs. Each arc is divided by equiangular rays which intersect chords between digitized points describing the arc. The radial distance of each ray is averaged within groups of foot lengths which vary by ± 2·25 mm (approximately equal to 1/2 shoe size). The method has been used to determine average plantar curves in a study of 1197 North American males (Hawes and Sovak 1993).     

A new approach to estimate fractal dimensions of corrosion images

A new approach is proposed based on box-counting method to estimate the fractal dimensions, D_2d and D_3d of corrosion images. They denote two-dimensional (2D) and three-dimensional (3D) characteristics of corroded surface morphology. The results have been tested through dealing with classical fractal figures, pit morphology of moon surface and practical corroded samples etc. to show that this new method is computationally simple, convenient and accurate. More specially, D_2d and D_3d have definite corrosion expressions, which respectively denote the fractal dimensions for pit diameter distribution and pit depth distribution on real corroded surface.     

A PLC-based modified-fuzzy controller for PWM-driven induction motor drive with constant V/Hz ratio control

In this paper, a method to develop and design a fuzzy-hybrid control on an industrial controller to control speed of an induction motor and implementing a constant V/Hz ratio control is presented. Detailed discussions on the controller for a PWM-driven induction motor drive system, the system identification for the model transfer function, and the analysis on output responses and the associated manipulated variables are presented. The control objective is to provide an effective control action to sudden changes in reference speed and/or load torque. A switching type controller consisting of two control modes are devised: a PID-type fuzzy controller consisting of a PI-type and a PD-type fuzzy controller, and a conventional PID. At the early phase of the control action, the control task is handled by the PID-type fuzzy controller. At a later phase when the absolute of error is less than a threshold value, the input of integrator at the output side is no longer given by fuzzy action but fed by the incremental PID action. In term of control action, this is an enhanced proportional and derivative action when the actual value is closed to reference. Detailed evaluations of the controller's performance based on pre-defined performance indices under several conditions are presented. The findings demonstrate the ability of the control approach to provide a viable control solution in response to the different operating conditions and requirements.     

A novel approach to determination of a transition function with repeated eigenvalues constant matrix

An analytical function of a matrix with repeated eigenvalues is expressed in terms of constituent matrices. Two approaches to computing the constituent matrices are then presented. For a special case of a companion matrix, the computation can be greatly simplified.     

A sketch-based approach to human body modelling

In this paper, we present a new approach and a novel interface, Virtual Human Sketcher (VHS), which enables those who can draw, to sketch-out various human body models. Our approach supports freehand drawing input and a “Stick Figure→Fleshing-out→Skin Mapping” modelling pipeline. Following this pipeline, a stick figure is drawn first to illustrate a figure pose, which is automatically reconstructed into 3D through a “Multi-layered Back-Front Ambiguity Clarifier”. It is then fleshed-out with freehand body contours. A “Creative Model-based Method” is developed for interpreting the body size, shape, and fat distribution of the sketched figure and transferring it into a 3D human body through graphical comparisons and generic model morphing. The generic model is encapsulated with three distinct layers: skeleton, fat tissue, and skin. It can be transformed sequentially through rigid morphing, fatness morphing, and surface matching to match the 2D figure sketch. The initial resulting 3D body model can be incrementally modified through sketching directly on the 3D model. In addition, this body surface can be mapped onto a series of posed stick figures to be interpolated as a 3D character animation. VHS has been tested by various users on Tablet PC. After minimal training, even a beginner can create plausible human bodies and animate them within minutes.     

A decentralized probabilistic approach to articulated body tracking

We present a novel decentralized probabilistic approach to visual tracking of articulated objects. Analyzing articulated motion is challenging because (1) the high degrees of freedom potentially demands tremendous computation, and (2) the solution is confronted by the numerous local optima existed in a high dimensional parametric space. To ease these problems, we propose a decentralized approach that analyzes limbs locally and reinforces the spatial coherence among them at the same time. The computational model of the proposed approach is based on a dynamic Markov network, a generative model which characterizes the dynamics, the image observations of each individual limb, as well as the spatial coherence among them. Probabilistic mean field variational analysis provides an efficient computational diagram to obtain the approximate inference of the motion posteriors. We thus design the mean field Monte Carlo (MFMC) algorithm, where a set of low dimensional particle filters interact with one another and solve the high dimensional problem collaboratively. We also present a variational maximum a posteriori (MAP) algorithm, which has a rigorous theoretic foundation, to approach to the optimal MAP estimate of the articulated motion. Both algorithms achieve linear complexity w.r.t. the number of articulated subparts and have the potential of parallel computing. Experiments on human body tracking demonstrate the significance, effectiveness and efficiency of the proposed methods.     

An active set algorithm to estimate parameters in generalized linear models with ordered predictors

In biomedical studies, researchers are often interested in assessing the association between one or more ordinal explanatory variables and an outcome variable, at the same time adjusting for covariates of any type. The outcome variable may be continuous, binary, or represent censored survival times. In the absence of precise knowledge of the response function, using monotonicity constraints on the ordinal variables improves efficiency in estimating parameters, especially when sample sizes are small. An active set algorithm that can efficiently compute such estimators is proposed, and a characterization of the solution is provided. Having an efficient algorithm at hand is especially relevant when applying likelihood ratio tests in restricted generalized linear models, where one needs the value of the likelihood at the restricted maximizer. The algorithm is illustrated on a real life data set from oncology.     

Periodic characteristic ratio (PCR) method: An alternative method to determine the characteristic polynomial

This paper proposes an alternative method to determine the characteristic polynomial based on closed loop desired transient response. To develop the method, we have found optimal characteristic rations in simple arrangement of these parameters via performance map method. Despite its simplicity, the resulted system exhibits better transient response in comparison with the systems obtained from existing methods of determining the characteristics polynomials. Numerical simulations are used to illustrate the specifications of the proposed method.     

An iterative approach to dynamic simulation of 3-D rigid-body motions for real-time interactive computer animation

A method is presented for approximating the motions of linked 3-dimensional rigid body systems that may be applied in the context of interactive motion specification for computer animation. The method is based on decoupling the ballistic (free) component of the motion of the points that constitute the solid, and the component due to the shape constraint of the solid. This allows for a conceptually simple and computationally efficient algorithm for motion specification.     

An approach to optimum combustion control using parallel type and cross-limiting type technique

In the paper, a new approach to the combustion control by introducing the parallel type air-fuel combustion control and cross-limiting type (or lead-lag type) combustion control technique designed in one control system in a boiler is presented. This new approached combustion control system is designed in such way that controlled the air-fuel ratio in furnace in parallel way for small steam demand variation and in cross-limiting way for high steam demand variation. This approach does not require any extra field instrumentation or modified process parameter. All original instruments are used to measure the process parameters for combustion control and final control elements controlled the process. It is shown that air and fuel flow can be successfully optimized for the required steam demand by new designed combustion control. The accurate air-fuel ratio obtained in the proposed technique also minimizes some problems of the conventional system like incomplete combustion during sudden load change, boiler stuck-up problem and bump problem. The complete derivation of the required mathematical models is reported in the paper. Performance of three boilers incorporated with the proposed system is observed for a long period and the performance report is presented. A very efficient performance in three boilers has been observed.     

Putting mind and body back together: A human-systems approach to the integration of the physical and cognitive dimensions of task design and operations

As human factors and ergonomics professionals we should be considering the total context within which the person must operate when performing a task, providing a service, or using a product. We have traditionally thought of the person as having a cognitive system and a physical system and much of our scientific literature has been myopically focused on one or the other of these systems while, in general, totally ignoring the other. However, contemporary efforts have begun to recognize the rich interactions occurring between these systems that can have a profound influence on performance and dictate overall system output. In addition, modern efforts are beginning to appreciate the many interactions between the various elements of the environment that can influence the components of the human systems. The next level of sophistication in the practice of human factors and ergonomics must begin to consider the totality of the human-system behavior and performance and must consider systems design interactions which result from these collective effects. Only then will we be able to truly optimize systems for human use.