Experimental Verification of the Number Relation at Room and Elevated Temperatures

The accuracy of the Neuber equation for predicting notch root stress-strain behavior at room temperature and at 650 C was experimentally investigated. Strains on notched specimens were measured with a non-contacting, interferometric technique and stresses were simulated with smooth specimens. Predictions of notch root stress-strain response were made from the Neuber Equation and smooth specimen behavior. Neuber predictions gave very accurate results at room temperature. However, the predicted interaction of creep and stress relaxation differed from experimentally measured behavior at 650 C

Cities for children: the effects of car use on their lives

9-11 June 2004 In Britain, children are walking less than they used to. A major factor causing this decrease is the growth in car use. These trends are reducing children’s quantity of physical activity, with serious implications for their health. The purpose of this paper is to explore these themes using results from a 3-year research project entitled ‘Reducing children’s car use: the health and potential car dependency impacts’ which has been carried out in the Centre for Transport Studies at University College London in collaboration with others including Hertfordshire County Council, with fieldwork being carried out in Hertfordshire, an area immediately north of London. A major component of the project was a study of 200 children aged between 10 and 13 years of age using motion sensors coupled with the use of a travel and activity diary over four days. The sensors measured movement in three dimensions which was converted to activity calories, a measure of physical activity. Events from the travel and activity diaries were mapped onto the data from the sensors so that it was possible to isolate and analyse specific time periods, events and journeys. From these data, the comparative effects of different forms of transport on children’s physical activity have been established, producing clear evidence of the benefits of walking compared with car travel. It is found that the use of the car is linked to particular types of activity. For example, structured out-of-home activities, such as clubs and sports lessons tend to be reached by car while informal activities such as playing, are associated more with walking. This means that the shift from the latter to the former is one of the factors underlying children’s increasing use of the car. The motion sensors have facilitated the calculation of the intensity of various activities in terms of using activity calories. Walking is second only to physical education (PE) or games lessons in intensity. It was found that, for the older children, walking to and from school for a week used more activity calories than two hours of PE or games lessons, which is the recommended standard in Britain. It was also found that children who walk to activities are more active when they arrive at activities than those who travel by car, particularly in the more energetic activities, which suggests that walking brings wider health benefits than is generally recognised. Another strand of the project upon which this paper is based is the evaluation of walking buses. From the various surveys in the study it appears that about half of the trips on walking buses were previously walked, but there is not an equivalent decrease in the number of car trips because many of the children were being dropped at school in the course of a longer trip by a parent

Increasing the amount of walking by children

Children’s car use is increasing. As a result of this, they are walking less. This has serious implications for their quantity of physical activity and consequently for their health. In this paper, findings are presented from a research project being carried out in the Centre for Transport Studies at University College London to examine these effects. A major element of the research involved fitting 200 children with portable motion sensors for a period of four days to measure their quantity of physical activity. In parallel with this, they kept travel and activity diaries, so that it was possible to establish how much energy they consumed in various activities, including walking. It is shown that walking to school for a week consumes more calories than one week’s worth of physical education (PE) and games lessons, and that children who walk to events tend to use more energy in participating in them than children who are driven by car. The effectiveness of a specific initiative to encourage children to shift from the car to walking, namely the walking bus, is examined in detail, and found to be effective in helping to achieve this objective

AN EXPERIMENTAL INVESTIGATION OF GASEOUS-FILM COOLING OF A ROCKET MOTOR

Gaseous-film cooling of rocket combustion chambe

Rapid prototyping and fast user trial of multimedia broadcast and cellular services

This paper presents the results of fast user trial of multimedia services that are enabled when a mobile terminal has access to converged services over digital broadcast and mobile telecommunications networks. It first describes the motivations behind developing this system and describes the service scenarios that benefit most from it. It then provides an overview of the service components of the test case scenario. Finally, it presents the results of fast user trials on end users of the services that were developed. This work was conducted as part of the EU-funded CISMUNDUS project

Magnetic and vibrational properties of high-entropy alloys

The magnetic properties of high-entropy alloys based on equimolar FeCoCrNi were investigated using vibrating sample magnetometry to determine their usefulness in high-temperature magnetic applications. Nuclear resonant inelastic x-ray scattering measurements were performed to evaluate the vibrational entropy of the ^(57)Fe atoms and to infer chemical order. The configurational and vibrational entropy of alloying are discussed as they apply to these high-entropy alloys

Distinguishing the opponents in the prisoner dilemma in well-mixed populations

Here we study the effects of adopting different strategies against different opponent instead of adopting the same strategy against all of them in the prisoner dilemma structured in well-mixed populations. We consider an evolutionary process in which strategies that provide reproductive success are imitated and players replace one of their worst interactions by the new one. We set individuals in a well-mixed population so that network reciprocity effect is excluded and we analyze both synchronous and asynchronous updates. As a consequence of the replacement rule, we show that mutual cooperation is never destroyed and the initial fraction of mutual cooperation is a lower bound for the level of cooperation. We show by simulation and mean-field analysis that for synchronous update cooperation dominates while for asynchronous update only cooperations associated to the initial mutual cooperations are maintained. As a side effect of the replacement rule, an "implicit punishment" mechanism comes up in a way that exploitations are always neutralized providing evolutionary stability for cooperation

Experimental verification of the Neuber relation at room and elevated temperatures

The accuracy of the Neuber equation at room temperature and 1,200 F as experimentally determined under cyclic load conditions with hold times. All strains were measured with an interferometric technique at both the local and remote regions of notched specimens. At room temperature, strains were obtained for the initial response at one load level and for cyclically stable conditions at four load levels. Stresses in notched members were simulated by subjecting smooth specimens to he same strains as were recorded on the notched specimen. Local stress-strain response was then predicted with excellent accuracy by subjecting a smooth specimen to limits established by the Neuber equation. Data at 1,200 F were obtained with the same experimental techniques but only in the cyclically stable conditions. The Neuber prediction at this temperature gave relatively accurate results in terms of predicting stress and strain points

Transition metal oxides using quantum Monte Carlo

The transition metal-oxygen bond appears prominently throughout chemistry and solid-state physics. Many materials, from biomolecules to ferroelectrics to the components of supernova remnants contain this bond in some form. Many of these materials' properties strongly depend on fine details of the TM-O bond and intricate correlation effects, which make accurate calculations of their properties very challenging. We present quantum Monte Carlo, an explicitly correlated class of methods, to improve the accuracy of electronic structure calculations over more traditional methods like density functional theory. We find that unlike s-p type bonding, the amount of hybridization of the d-p bond in TM-O materials is strongly dependant on electronic correlation.Comment: 20 pages, 4 figures, to appear as a topical review in J. Physics: Condensed Matte