Implementing Racing AI using Q-Learning and Steering Behaviours

Artificial intelligence has become a fundamental component of modern computer games as developers are producing ever more realistic experiences. This is particularly true of the racing game genre in which AI plays a fundamental role. Reinforcement learning (RL) techniques, notably Q-Learning (QL), have been growing as feasible methods for implementing AI in racing games in recent years. The focus of this research is on implementing QL to create a policy which the AI agents to utilise in a racing game using the Unity 3D game engine. QL is used (offline) to teach the agent appropriate throttle values around each part of the circuit whilst the steering is handled using a predefined racing line. Two variations of the QL algorithm were implemented to examine their effectiveness. The agents also make use of Steering Behaviours (including obstacle avoidance) to ensure that they can adapt their movements in real-time against other agents and players. Initial experiments showed that both types performed well and produced competitive lap times when compared to a player

Measurement and modelling of mass diffusion coefficients for application in carbon dioxide storage and enhanced oil recovery

In this work, measurements were carried out by the Taylor dispersion method [1, 2] to determine the mutual diffusion coefficient for CO2 in water or hydrocarbon at effectively infinite dilution. Measurements were carried out for CO2 in water, hexane, heptane, octane, decane, dodecane, hexadecane, cyclohexane, squalane and toluene at temperatures between 298 K and 423 K with pressures up to 69 MPa. Measurements of CO2 diffusivity in different brines were also carried out by 13C pulsed-field gradient NMR

Measurements and Modelling of Vapour–Liquid Equilibrium for (H2O + N2) and (CO2 + H2O + N2) Systems at Temperatures between 323 and 473 K and Pressures up to 20 MPa

Understanding the phase behaviour of (CO2 + water + permanent gas) systems is critical for implementing carbon capture and storage (CCS) processes, a key technology in reducing CO2 emissions. In this paper, phase behaviour data for (H2O + N2) and (CO2 + H2O + N2) systems are reported at temperatures from 323 to 473 K and pressures up to 20 MPa. In the ternary system, the mole ratio between CO2 and N2 was 1. Experiments were conducted in a newly designed analytical apparatus that includes two syringe pumps for fluid injection, a high-pressure equilibrium vessel, heater aluminium jacket, Rolsi sampling valves and an online gas chromatograph (GC) for composition determination. A high-sensitivity pulsed discharge detector installed in the GC was used to measure the low levels of dissolved nitrogen in the aqueous phase and low water levels in the vapour phase. The experimental data were compared with the calculation based on the γ-φ and SAFT-γ Mie approaches. In the SAFT-γ Mie model, the like parameters for N2 had to be determined. We also obtained the unlike dispersion energy for the (H2O + N2) system and the unlike repulsive exponent and dispersion energy for the (CO2 + N2) system. This was done to improve the prediction of SAFT-γ Mie model. For the (H2O + N2) binary system, the results show that the solubility of nitrogen in the aqueous phase was calculated better by the γ-φ approach rather than the SAFT-γ Mie model, whereas SAFT-γ Mie performed better for the prediction of the vapour phase. For the (CO2 + H2O + N2) ternary systems, both models predicted the experimental data for each phase with good agreement

Saturated Phase Densities of (CO2 + Methylcyclohexane) at Temperatures from (298 to 448) K and Pressures up to the Critical Pressure

This work reports saturated-phase densities for the CO2 + methylcyclohexane system at temperatures between 298 and 448 K and at pressures up to the critical pressure. The densities were measured with a standard uncertainty of <1.5 kg·m-3 and were fitted along isotherms with a recently developed nonlinear empirical correlation with an absolute average deviation (ΔAAD) of about 1.5 kg·m-3. This empirical correlation also allowed the estimation of the critical pressure and density at each temperature, and the obtained critical pressures were found to be in close agreement with previously published data. We also compare both our density data and vapor-liquid equilibrium (VLE) data from the literature with the predictions from two models: PPR-78 and SAFT-γMie. The results show that densities were predicted better with SAFT-γMie than with PPR-78, whereas PPR-78 generally performed better for VLE. This could indicate that some of the unlike parameters of SAFT-γMie could be further optimized

Testing the neutrality of matter by acoustic means in a spherical resonator

New measurements to test the neutrality of matter by acoustic means are reported. The apparatus is based on a spherical capacitor filled with gaseous SF$_6$ excited by an oscillating electric field. The apparatus has been calibrated measuring the electric polarizability. Assuming charge conservation in the $\beta$ decay of the neutron, the experiment gives a limit of $\epsilon_\text{p-e}\lesssim1\cdot10^{-21}$ for the electron-proton charge difference, the same limit holding for the charge of the neutron. Previous measurements are critically reviewed and found incorrect: the present result is the best limit obtained with this technique

An industrial reference fluid for moderately high viscosity

In industrial practice, there is a demand for a reference standard for viscosity that is established for a readily available fluid to simplify the calibration of industrial viscometers for moderately high viscosities [(50 to 125) mPa · s]. Diisodecyl phthalate (DIDP) has been suggested as that reference fluid, and a number of studies of its properties have been carried out in several laboratories throughout the world, within the auspices of a project coordinated by the International Association for Transport Properties. That project has now progressed to the point where it is possible to collate the results of studies of the viscosity of the fluid by a number of different techniques, so as to lead to a proposed standard reference value which will be included in the paper. To support this recommended value, the various measurements conducted have been critically reviewed, and the sample purity and other factors affecting the viscosity have been studied. Density and surface tension measurements have also been performed. This paper does not describe the individual viscosity determinations carried out in independent laboratories because these are the subject of individual publications, but it does describe the ancillary studies conducted and their relevance to the viscosity standard. In addition, the paper contains recommended values for the viscosity of liquid DIDP. The samples of DIDP to which the recommended values refer are isomeric mixtures available commercially from certain suppliers, with a minimum purity by gas chromatography of 99.8 %. The recommended values result from a critical examination of all the measurements conducted to date and are supported by careful arguments dealing with the likely effects of the isomeric content of the sample as well as of other impurities. The proposed reference standard is intended particularly to serve an industrial need for a readily available calibration material with a viscosity close to that required in practical situations. To that end, the recommended value has an overall relative uncertainty of approximately 1 %. It is therefore not intended to supersede for the reference value for the viscosity of water at 20 °C, which is known much more accurately, but rather to complement it

A diverse Pleistocene marsupial trackway assemblage from the Victorian Volcanic Plains, Australia

A diverse assemblage of late Pleistocene marsupial trackways on a lake bed in south-western Victoria provides the first information relating to the gaits and morphology of several megafaunal species, and represents the most speciose and best preserved megafaunal footprint site in Australia. The 60-110 ka volcaniclastic lacustrine sedimentary rocks preserve trackways of the diprotodontid Diprotodon optatum, a macropodid (probably Protemnodon sp.) and a large vombatid (perhaps Ramsayia magna or '. Phascolomys' medius) and possible prints of the marsupial lion, Thylacoleo carnifex. The footprints were imprinted within a short time period, demonstrating the association of the taxa present, rather than the time-averaged accumulations usually observed in skeletal fossil deposits. Individual manus and pes prints are distinguishable in some trackways, and in many cases some digital pad morphology is also present. Several parameters traditionally used to differentiate ichnotaxa, including trackway gauge and the degree of print in-turning relative to the midline, are shown to be subject to significant intraspecific variation in marsupials. Sexual dimorphism in the trackway proportions of Diprotodon, and its potential for occurrence in all large bodied, quadrupedal marsupials, is identified here for the first time