Underwater simulation of a lunar-surface traverse

Underwater simulation of lunar surface travers

Shock reflection and surface effects in the shock tube

A thin-film resistance thermometer, mounted on the end-wall of a shock tube, is used to record surface temperatures and heat transfer rates following reflection of the primary shock wave. This information is combined with the results of theoretical investigations to produce simultaneous information about surface accommodation effects and gas thermal conductivities at high pressures and moderate temperatures

Finding symmetry in models of concurrent systems by static channel diagram analysis

Over the last decade there has been much interest in exploiting symmetry to combat the state explosion problem in model checking. Although symmetry in a model often arises as a result of symmetry in the topology of the system being modelled, most model checkers which exploit structural symmetry are limited to topologies which exhibit total symmetries, such as stars and cliques. We define the static channel diagram of a concurrent, message passing program, and show that under certain restrictions there is a correspondence between symmetries of the static channel diagram of a program and symmetries of the Kripke structure associated with the program. This allows the detection, and potential exploitation, of structural symmetry in systems with arbitrary topologies. Our method of symmetry detection can handle mobile systems where channel references are passed on channels, resulting in a dynamic communication structure. We illustrate our results with an example using the Promela modelling language

Perceived noisiness under anechoic, semi-reverberant and earphone listening conditions

Magnitude estimates by each of 31 listeners were obtained for a variety of noise sources under three methods of stimuli presentation: loudspeaker presentation in an anechoic chamber, loudspeaker presentation in a normal semi-reverberant room, and earphone presentation. Comparability of ratings obtained in these environments were evaluated with respect to predictability of ratings from physical measures, reliability of ratings, and to the scale values assigned to various noise stimuli. Acoustic environment was found to have little effect upon physical predictive measures and ratings of perceived noisiness were little affected by the acoustic environment in which they were obtained. The need for further study of possible differing interactions between judged noisiness of steady state sound and the methods of magnitude estimation and paired comparisons is indicated by the finding that in these tests the subjects, though instructed otherwise, apparently judged the maximum rather than the effective magnitude of steady-state noises

Hybrid superconducting quantum magnetometer

A superconducting quantum magnetometer based on magnetic flux-driven modulation of the density of states of a proximized metallic nanowire is theoretically analyzed. With optimized geometrical and material parameters transfer functions up to a few mV/Phi_0 and intrinsic flux noise ~10^{-9}Phi_0 Hz^{-1/2} below 1 K are achievable. The opportunity to access single-spin detection joined with limited dissipation (of the order of ~ 10^{-14} W) make this magnetometer interesting for the investigation of the switching dynamics of molecules or individual magnetic nanoparticles.Comment: 6 pages, 6 color figures, added calculation of the Josephson current, published versio

Ageing of Natural Rubber under Stress

We report a dynamical-mechanical study of stress relaxation at small deformation in a natural (polyisoprene) rubber well above its glass transition temperature Tg. We find that an almost complete relaxation of stress takes place over very long periods of time, even though the elastic network integrity is fully retained. The relaxation rate and the long-time equilibrium modulus are sensitive functions of temperature which do not follow time-temperature superposition. Many characteristic features of non-ergodic ageing response are apparent at both short and very long times. We interpret the observed behaviour in terms of the properties of rubber crosslinks, capable of isomerisation under stress, and relate the results to recent models of soft glassy rheology.Comment: Latex 2e (EPJ style), 5 EPS figure

The methods of paired comparisons and magnitude estimation in judging the noisiness of aircraft

The point of subjective equality in regard to perceived noisiness for each of 14 pairs of aircraft noises was obtained using both magnitude estimation technique and the method of paired comparisons. Both methods gave approximately the same estimates of the points of subjective equality for the noise pairs, and both showed similar correspondence to predictive physical measures. Nevertheless, the two methods appear to have greater face validity to the listeners. However, the magnitude estimation technique appears to be more efficient; for a given level of reliability it requires approximately 50% of the testing time required by the paired comparison method. The functions relating physical intensity to the estimated magnitude of subjective noisiness had slopes ranging from about .61 to .29 for the aircraft noises employed in this study, indicating a required change of about 5 to 10 db for a doubling in subjective magnitude. Some physical units of noise measurement were found to be very predictive (standard errors of estimate as low as 1.9 db) of the subjective judgements of noisiness

Vehicle infrastructure cooperative localization using Factor Graphs

Highly assisted and Autonomous Driving is dependent on the accurate localization of both the vehicle and other targets within the environment. With increasing traffic on roads and wider proliferation of low cost sensors, a vehicle-infrastructure cooperative localization scenario can provide improved performance over traditional mono-platform localization. The paper highlights the various challenges in the process and proposes a solution based on Factor Graphs which utilizes the concept of topology of vehicles. A Factor Graph represents probabilistic graphical model as a bipartite graph. It is used to add the inter-vehicle distance as constraints while localizing the vehicle. The proposed solution is easily scalable for many vehicles without increasing the execution complexity. Finally simulation indicates that incorporating the topology information as a state estimate can improve performance over the traditional Kalman Filter approac

Development and demonstration of a renewable energy based demand/supply decision support tool for the building design profession

Future cities are likely to be characterised by a greater level of renewable energy systems deployment. Maximum impact will be achieved when such systems are used to offset local energy demands in contrast to current philosophy dictating the grid connection of large schemes. This paper reports on the development of a software tool, MERIT, for demand/ supply matching. The purpose of MERIT is to assist with the deployment of renewable energy systems at all scales. This paper describes the procedures used to match heterogeneous supply technologies to a set of demand profiles corresponding to the different possible fuel types