Comparison of two scaling approaches for the development of biomechanical multi-body human models

Dimensional scaling approaches are widely used to develop multi-body human models in injury biomechanics research. Given the limited experimental data for any particular anthropometry, a validated model can be scaled to different sizes to reflect the biological variance of population and used to characterize the human response. This paper compares two scaling approaches at the whole-body level: one is the conventional mass-based scaling approach which assumes geometric similarity; the other is the structure-based approach which assumes additional structural similarity by using idealized mechanical models to account for the specific anatomy and expected loading conditions. Given the use of exterior body dimensions and a uniform Young’s modulus, the two approaches showed close values of the scaling factors for most body regions, with 1.5 % difference on force scaling factors and 13.5 % difference on moment scaling factors, on average. One exception was on the thoracic modeling, with 19.3 % difference on the scaling factor of the deflection. Two 6-year-old child models were generated from a baseline adult model as application example and were evaluated using recent biomechanical data from cadaveric pediatric experiments. The scaled models predicted similar impact responses of the thorax and lower extremity, which were within the experimental corridors; and suggested further consideration of age-specific structural change of the pelvis. Towards improved scaling methods to develop biofidelic human models, this comparative analysis suggests further investigation on interior anatomical geometry and detailed biological material properties associated with the demographic range of the population.     

How to Trap the Network Intruder

Abstract

There is a level of sensitivity to almost all data, but what is most important — keeping sensitive data sensitive or guaranteeing the integrity of the data? When it comes to sensitivity or integrity, access control models have provided several options. Yet, wouldn't a combination of access control models provide a more desirable result than just settling for one? Is it possible to have a slice of data sensitivity with a dollop of data integrity? In finding the answer to this question it must be understood exactly what an access control model is and, in terms of sensitivity and integrity, which models provide the best security.     

Two for the General Audience Plus a Survey on BI

Abstract

The research in this paper considers the complex and dynamic arrangements for potential and actual knowledge sharing in interorganizational networks. The essence of this stance is that “knowledge” relates to affirmative managerial action beyond the necessary collection of information facilitated through technology. The issue is to determine the nature and extent of the degree of organizational agreement that may be achieved as competitors either cooperate or continue to compete in the face of challenging and pervasive market conditions. The theory relating to network formulation is reviewed, findings from empirical analyses from the experiences from automobile distributors in a large USA city, and one scientific collaborators network are presented. A framework is proposed identifying the factors necessary to initially construct the network and then to further sustain it over time. A number of lessons learned are developed, which are believed to be of value to researchers and practitioners engaged in these processes.     

(Approximate) Uncertain Skylines

Given a set of points with uncertain locations, we consider the problem of computing the probability of each point lying on the skyline, that is, the probability that it is not dominated by any other input point. If each point’s uncertainty is described as a probability distribution over a discrete set of locations, we improve the best known exact solution. We also suggest why we believe our solution might be optimal. Next, we describe simple, near-linear time approximation algorithms for computing the probability of each point lying on the skyline. In addition, some of our methods can be adapted to construct data structures that can efficiently determine the probability of a query point lying on the skyline.     

Calculus Students' Use and Interpretation of Variables: Algebraic vs. Arithmetic Thinking

Abstract

The ability to use and interpret algebraic variables as generalized numbers and changing quantities is fundamental to the learning of calculus. This study considers the use of variables in these advanced ways as a component of algebraic thinking. College introductory calculus students' (n = 174) written responses to algebra problems requiring the use and interpretation of variables as changing quantities were examined for evidence of algebraic and arithmetic thinking. A framework was developed to describe and categorize examples of algebraic, transitional, and arithmetic thinking reflected in these students' uses of variables. The extent to which students' responses showed evidence of algebraic or arithmetic thinking was quantified and related to their course grades. Only one third of the responses of these entering calculus students were identified as representative of algebraic thinking. This study extends previous research by showing that evidence of algebraic thinking in students' work was positively related to successful performance in calculus.     

A Rigorous Architectural Approach to Adaptive Software Engineering

The engineering of distributed adaptive software is a complex task which requires a rigorous approach. Software architectural (structural) concepts and principles are highly beneficial in specifying, designing, analysing, constructing and evolving distributed software. A rigorous architectural approach dictates formalisms and techniques that are compositional, components that are context independent and systems that can be constructed and evolved incrementally. This paper overviews some of the underlying reasons for adopting an architectural approach, including a brief “rational history” of our research work, and indicates how an architectural model can potentially facilitate the provision of self-managed adaptive software system. Much of the research has been supported by the Engineering and Physical Sciences Research Council and is currently partly supported by EPSRC Platform grant AEDUS 2 and a DTC grant.     

An Investigation of Cheating in Online Games

Cheating is rampant in current gameplay on the Internet. However, it isn't as well understood as we might expect. The authors summarize the various known methods of cheating and define a taxonomy of online game cheating with respect to the underlying vulnerability, consequence, and cheating principal. This taxonomy provides a systematic introduction to the characteristics of cheats in online games and how they can arise. Although cheating in online games is largely due to various security failures, the four traditional aspects of security—confidentiality, integrity, availability, and authenticity—are insufficient to explain it. Instead, fairness becomes a vital additional aspect, and its enforcement provides a convincing perspective for understanding security techniques' role in developing and operating online games.