Virtual reality simulated aircraft flyovers: Influence of the landscape on the overall pleasantness of the environment.

To give residents better understanding of the impact of future airport scenarios, a virtual reality application with sound simulation will be tested in the frame of the European ANIMA project. The set-up has been evaluated in laboratory before being used in real situation. This paper presents the laboratory experiment whose aim is to assess the application's relevance for simulating flyovers. Although the perceptual experiment is designed to test the influence of aircraft vision crossed with aircraft sound, this paper focusses only on the impact of the landscape where the flyovers are observed. Two landscapes (park and buildings) are presented to 60 participants, in balanced order, with 12 audio-visual stimuli in both landscapes. Participants had to rate four differential semantic scales. Globally there is no influence of the landscape on the overall pleasantness, but when looking at the individual answers, it appears that three groups of participants can be discriminated. The majority of people do not change their pleasantness ratings in both landscapes, but some participants prefer experiencing the flyovers in the park landscape because it is visually more pleasant, and others prefer the opposite because it is more annoying to be submitted to aircraft noise in a green park landscape.

Aerodynamic and Aeroacoustic Performance of Tail Rotor Investigation and Modification

With the increasingly stringent airworthiness standards, the noise generated during the rotorcraft flight is gradually attracting people’s attention. It widely operated helicopters at low altitudes because of their maneuverability. The way to reduce the noise caused by the complex airflow of the helicopter rotor system has progressively become a hot topic for researchers. Using a hybrid acoustic analysis method, this paper investigates the improvement of the noise and thrust of the helicopter’s tail rotor through the tail rotor structural parameters. For the basic model, the turbulence simulation is performed using an incompressible detached eddy simulation (DES) method, and the Lighthill acoustic analog equation is calculated using the finite element method (FEM). We verified the accuracy of the method through wind tunnel tests. We chose a series of structural parameters for sound simulation and fluid simulation calculations. The results indicate that the modified tail rotor noise reduced by 16.5 dBA and the total thrust increased by 19.9% from the prototype model. This work can enhance the duct tail rotor design to improve aerodynamic and aeroacoustic performance.

Effective thermal conductivity in granular media with devolatilization: the Lattice Boltzmann modelling

Flow thermomechanics in reactive porous media is of importance in industry including the thermal processing of fossil fuel (coking understood as a slow pyrolysis) involving devolatilisation. On the way to provide a detailed description of the process, a multi-scale approach was chosen to estimate effective transport coefficients. For this case the Lattice Boltzmann method (LBM) was used due to its advantages to accurately model multi-physics and chemistry in a random geometry of granular media. After account for earlier studies, the paper presents description of the model with improved boundary conditions and a benchmark case. Results from meso-scale LBM calculations are presented and discussed regarding the spatial resolution and the choice of relaxation parameter along its influence on the accuracy compared with empirical formulae. Regarding the estimation of effective thermal conductivity coefficient it is shown that occurrence of devolatilization has a crucial effect by reducing heat transfer. Some quantitative results characterise the propagation of thermal front; also presented is the evolution of effective thermal conductivity. The work is a step forward towards a physically sound simulation of thermal processing of fossil fuel.

Pragmatic reuse for DSML development

By bridging the semantic gap, domain-specific language (DSLs) serve an important role in the conquest to allow domain experts to model their systems themselves. In this publication we present a case study of the development of the Continuous REactive SysTems language (CREST), a DSL for hybrid systems modeling. The language focuses on the representation of continuous resource flows such as water, electricity, light or heat. Our methodology follows a very pragmatic approach, combining the syntactic and semantic principles of well-known modeling means such as hybrid automata, data-flow languages and architecture description languages into a coherent language. The borrowed aspects have been carefully combined and formalised in a well-defined operational semantics. The DSL provides two concrete syntaxes: CREST diagrams, a graphical language that is easily understandable and serves as a model basis, and , an internal DSL implementation that supports rapid prototyping—both are geared towards usability and clarity. We present the DSL’s semantics, which thoroughly connect the various language concerns into an executable formalism that enables sound simulation and formal verification in , and discuss the lessons learned throughout the project.