Predicting the metabolic energy costs of bipedalism using evolutionary robotics

To understand the evolution of bipedalism among the homnoids in an ecological context we need to be able to estimate theenerrgetic cost of locomotion in fossil forms. Ideally such an estimate would be based entirely on morphology since, except for the rare instances where footprints are preserved, this is hte only primary source of evidence available. In this paper we use evolutionary robotics techniques (genetic algoritms, pattern generators and mechanical modeling) to produce a biomimentic simulation of bipedalism based on human body dimensions. The mechnaical simulation is a seven-segment, two-dimensional model with motive force provided by tension generators representing the major muscle groups acting around the lower-limb joints. Metabolic energy costs are calculated from the muscel model, and bipedal gait is generated using a finite-state pattern generator whose parameters are produced using a genetic algorithm with locomotor economy (maximum distance for a fixed energy cost) as the fitness criterion. The model is validated by comparing the values it generates with those for modern humans. The result (maximum efficiency of 200 J m-1) is within 15% of the experimentally derived value, which is very encouraging and suggests that this is a useful analytic technique for investigating the locomotor behaviour of fossil forms. Initial work suggests that in the future this technique could be used to estimate other locomotor parameters such as top speed. In addition, the animations produced by this technique are qualitatively very convincing, which suggests that this may also be a useful technique for visualizing bipedal locomotion

Using evolutionary robotics to estimate maximum running speeds under non-Earth gravitational conditions

The 11th International Symposium on Adaptive Motion of Animals and Machines. Kobe University, Japan. 2023-06-06/09. Adaptive Motion of Animals and Machines Organizing Committee.Poster Session P2

Understanding the Impact of Cellulose and Chitin-Based Nanomaterials in Various Polymer Matrix Constructs

Cellulose nanocrystals (CNCs) and chitin nanofibers (ChNFs) derived from trees and crab shells, respectively, were incorporated into poly(vinyl alcohol) (PVA) to generate tricomponent polymer composites. Nanomaterial processing conditions generated CNCs that were left with a negative surface charge, while ChNFs possessed a positive surface charge. Their subsequent incorporation into PVA offered the unique ability to generate nanocomposite films, hydrogels, and aerogels without the aid of additional chemicals, which allowed for assessment of how reinforcement transferred between constructs and expanded the range of commercial applications that CNCs and ChNFs can be applied. Results of this study indicated that specific ratios between CNCs and ChNFs enhanced the mechanical properties beyond that of what is capable with singular nanofillers, which was attributed to electrostatic and particle shape/size synergy between the nanomaterial components. These materials were generated into a hydrogel/aerogel hybrid composite material for a biomimetic medical device.Ph.D

Replacing the Social Security Tax with a Value-Added Tax: Policy Perspectives

On October 22, 1979, Representative Al Ullman (D-Ore.), then Chairman of the House Ways and Means Committee, introduced the Tax Restructuring Act of 1979, which would have lowered the rates of the individual income, corporate income and social security taxes along with certain other tax benefits and would have replaced the lost revenues from such reductions with the revenues from a 10% value-added tax (VAT). The introduction of the bill followed a speech delivered by Sen. Russell B. Long (D-La.), then Chairman of the Senate Finance Committee, at the 1978 Tulane Tax Institute, in which he advocated an overhaul of the tax system similar to the proposals contained in Ullman\u27s bill. Although there was nothing particularly novel in the proposals of Long and Ullman, the mere fact that the two members of Congress with the most influence over tax legislation were advocating a major overhaul of the entire tax system was enough to spark a lively debate on the merits of substituting a value-added tax for part or all of the components making up the present federal tax system in the United States

Evaluating alternative gait strategies using evolutionary robotics

Evolutionary robitics is a branch of artificial intelligence concerned with the automatic generation of autonomous robots. Usually the form of the robit is predefined an various computational techniques are used to control the machine's behaviour. One aspect is the spontaneous generation of walking in legged robots and this can be used to investigate the mechanical requiements for efficient walking in bipeds. This paper demonstrates a bipedal simulator that spontaneously generates walking and running gaits. The model can be customized to represent a range of hominoid morphologies and used to predict performance paramets such as preferred speed and metabolic energy cost. Because it does not require any motion capture data it is particularly suitable for investigating locomotion in fossil animals. The predictoins for modern humans are highly accurate in terms of energy cost for a given speend and thus the values predicted for other bipeds are likely to be good estimates. To illustrate this the cost of transport is calculated for Australopithecus afarensis. The model allows the degree of maximum extension at the knee to be varied causing the model to adopt walking gaits varying from chimpanzee-like to human=like. The energy costs associated with these gait choices can thus be calculated and this information used to evaluate possible locomotor strategies in early hominid

1-D Transient Thermal Modeling of an Ablative Material (MCC-1) Exposed to a Simulated Convective Titan 4 Launch Environment

The purpose of the work is to demonstrate that the flat test panel substrate temperatures are consistent with analysis predictions for MCC-1 applied to a aluminum substrate. The testing was performed in an aerothermal facility on samples of three different thicknesses of MCC-1 on an aluminum substrate. The results of the test were compared with a Transient Thermal model. The key assumptions of the Transient Thermal model were: (1) a one-dimensional heat transfer; (2) a constant ablation recession rate (determined from pre and post-test measurements); (3) ablation temperature of 540 degrees F; (4) Char left behind the ablation front; and (5) temperature jump correction for incident heat transfer coefficient. Two methods were used to model the heating of bare MCC-1: (1) Directly input surface temperature as a function of time; and (2) Aerothermal heating using calibration plate data and subtracting the radiation losses to tunnel walls. The results are presented as graphs. This article is presented in Viewgraph format

Psychological Health Influences of Legal-Marriage and -Partnerships on Same-Sex Couples

This chapter explores whether Californians in same-sex legal marriages and partnerships reported lower levels of psychological distress than other adult Californians after the 2008 California Supreme Court Decision that legalized same-sex marriage. We pooled 10 years of California Health Interview Survey (CHIS) data and employ a T1-T2 design to approximate a time series design. Dependent variables include overall self-related health, psychological distress, and household income. Independent variables include sexual identity and same-sex spouse. Bi-variate analyses compared self-reported mental and physical health between the two periods. We found decreased reports of poorer health and increased reports of very good health among gay men and lesbian women with legal spouses. Psychological distress decreased for legally coupled gay men and lesbians while increased slightly among unpartnered lesbian women and gay men. Household income increased among coupled lesbian women and gay men and decreased among others. Our project demonstrated positive health influences for Californians with legal same-sex spouses. We recommend future research projects that explore whether and how same- and opposite-sex marriage benefits health, well-being, and prosperity, and for marital status survey questions that are inclusive of sexual and gender identities and elicit the sex/gender of a respondent’s spouse