Virtual cities management and organisation

This paper presents a recent overview of the increasing use of Virtual Reality (VR) technologies for the simulation of urban environments. It builds on previous research conducted on the identification of three-dimensional (3D) city models and offers an analysis of the development, utilization and construction of VR city models. Issues pertaining to advantages, barriers and ownership are identified. The paper describes a case study of the development of a VR model for the city of Newcastle upon Tyne in the UK and outlines the role that academic institutions can play in both the creation and utilization of urban models. The study offers a new approach for the creation, management and update of urban models and reflects on issues which are emerging. Areas for future research are discussed

An overview of virtual city modelling : emerging organisational issues

This paper presents a recent overview of the increasing use of Virtual Reality (VR) technologies for the simulation of urban environments. It builds on previous research conducted on the identification of three-dimensional (3D) city models and offers an analysis of the development, utilization and construction of VR city models. Issues pertaining to advantages, barriers and ownership are identified. The paper describes a case study of the development of a VR model for the city of Newcastle upon Tyne in the UK and outlines the role that academic institutions can play in both the creation and utilization of urban models. The study offers a new approach for the creation, management and update of urban models and reflects on issues which are emerging. Areas for future research are discussed

Heat pumping in nanomechanical systems

We propose using a phonon pumping mechanism to transfer heat from a cold to a hot body using a propagating modulation of the medium connecting the two bodies. This phonon pump can cool nanomechanical systems without the need for active feedback. We compute the lowest temperature that this refrigerator can achieve.Comment: 4 pages, 1 figure, published versio

Virtual Reality Interactive Learning Environment

Open Building Manufacturing (ManuBuild) aims to promote the European construction industry beyond the state of the art. However, this requires the different stakeholders to be well informed of what ‘Open Building Manufacturing’ actually entails with respect to understanding the underlying concepts, benefits and risks. This is further challenged by the ‘traditional ways of learning’ which have been predominantly criticised for being entrenched in theories with little or no emphasis on practical issues. Experiential learning has long been suggested to overcome the problems associated with the traditional ways of learning. In this respect, it has the dual benefit of appealing to adult learner's experience base, as well as increasing the likelihood of performance change through training. On-the-job-training (OJT) is usually sought to enable ‘experiential’ learning; and it is argued to be particularly effective in complex tasks, where a great deal of independence is granted to the task performer. However, OJT has been criticised for being expensive, limited, and devoid of the actual training context. Consequently, in order to address the problems encountered with OJT, virtual reality (VR) solutions have been proposed to provide a risk free environment for learning without the ‘do-or-die’ consequences often faced on real construction projects. Since ManuBuild aims to promote the EU construction industry beyond the state of the art; training and education therefore needs also to go beyond the state of the art in order to meet future industry needs and expectations. Hence, a VR interactive learning environment was suggested for Open Building Manufacturing training to allow experiential learning to take place in a risk free environment, and consequently overcome the problems associated with OJT. This chapter discusses the development, testing, and validation of this prototype

Leakage flow simulation in a specific pump model

This paper deals with the influence of leakage flow existing in SHF pump model on the analysis of internal flow behaviour inside the vane diffuser of the pump model performance using both experiments and calculations. PIV measurements have been performed at different hub to shroud planes inside one diffuser channel passage for a given speed of rotation and various flow rates. For each operating condition, the PIV measurements have been trigged with different angular impeller positions. The performances and the static pressure rise of the diffuser were also measured using a three-hole probe. The numerical simulations were carried out with Star CCM+ 8.06 code (RANS frozen and unsteady calculations). Comparisons between numerical and experimental results are presented and discussed for three flow rates. The performances of the diffuser obtained by numerical simulation results are compared to the performances obtained by three-hole probe indications. The comparisons show few influence of fluid leakage on global performances but a real improvement concerning the efficiency of the impeller, the pump and the velocity distributions. These results show that leakage is an important parameter that has to be taken into account in order to make improved comparisons between numerical approaches and experiments in such a specific model set up

Comparisons RANS and URANS numerical results with experiments in a vaned diffuser of a centrifugal pump

the paper presents the analysis of the performance and the internal flow behaviour in the vaned diffuser of a radial flow pump using PIV (particles image velocimetry) technique, pressure probe traverses and numerical simula\u2011 tions. PIV measurements have been performed at different hub to shroud planes inside one diffuser channel passage for a given rotational speed and various flow rates. For each operating condition, PIV measurements have been made for differ\u2011 ent angular positions of the impeller. Probe traverses have also been performed using a 3 holes pressure probe from hub to shroud diffuser width at different radial locations in between the two diffuser geometrical throats. the numerical simulations were realized with the two commercial codes: i\u2011Star CCM+ 8.02.011 (rAnS (reynolds Averaged navier Stokes) turbu\u2011 lence model, frozen rotor and unsteady calculations), ii\u2011CFX 10.0 (turbulence modelled with DeS model (Detached eddy Simulation) combining rAnS with leS (large eddy Simulation), unsteady calculations). Comparisons between numerical (fully unsteady calculations) and experimental results are presented and discussed for two flow rates. In this respect, the effects of fluid leakage due to the gap between the rotating and fixed part of the pump model are analysed and discussed

The Analysis of design and manufacturing tasks using haptic and immersive VR - Some case studies

The use of virtual reality in interactive design and manufacture has been researched extensively but the practical application of this technology in industry is still very much in its infancy. This is surprising as one would have expected that, after some 30 years of research commercial applications of interactive design or manufacturing planning and analysis would be widespread throughout the product design domain. One of the major but less well known advantages of VR technology is that logging the user gives a great deal of rich data which can be used to automatically generate designs or manufacturing instructions, analyse design and manufacturing tasks, map engineering processes and, tentatively, acquire expert knowledge. The authors feel that the benefits of VR in these areas have not been fully disseminated to the wider industrial community and - with the advent of cheaper PC-based VR solutions - perhaps a wider appreciation of the capabilities of this type of technology may encourage companies to adopt VR solutions for some of their product design processes. With this in mind, this paper will describe in detail applications of haptics in assembly demonstrating how user task logging can lead to the analysis of design and manufacturing tasks at a level of detail not previously possible as well as giving usable engineering outputs. The haptic 3D VR study involves the use of a Phantom and 3D system to analyse and compare this technology against real-world user performance. This work demonstrates that the detailed logging of tasks in a virtual environment gives considerable potential for understanding how virtual tasks can be mapped onto their real world equivalent as well as showing how haptic process plans can be generated in a similar manner to the conduit design and assembly planning HMD VR tool reported in PART A. The paper concludes with a view as to how the authors feel that the use of VR systems in product design and manufacturing should evolve in order to enable the industrial adoption of this technology in the future

Supersymmetry-generated complex optical potentials with real spectra

We show that the formalism of supersymmetry (SUSY), when applied to parity-time (PT) symmetric optical potentials, can give rise to novel refractive index landscapes with altogether non-trivial properties. In particular, we find that the presence of gain and loss allows for arbitrarily removing bound states from the spectrum of a structure. This is in stark contrast to the Hermitian case, where the SUSY formalism can only address the fundamental mode of a potential. Subsequently we investigate isospectral families of complex potentials that exhibit entirely real spectra, despite the fact that their shapes violate PT-symmetry. Finally, the role of SUSY transformations in the regime of spontaneously broken PT symmetry is investigated.Comment: 6 pages, 4 figure