Abstract

Since its invention in the 1960s, Computed Tomography has become one of the most powerful and versatile non-destructive imaging tools, with applications ranging from biomedicine to concrete technology. For about two decades, it is also common to use CT images as the basis for Finite Element modeling of the scanned objects. Thereby, the main focus has been classically laid upon the accurate representation of geometrical details, while particularly for solids made up of natural non-homogeneous materials, the question of material property assignment has remained an open challenge over the years.

Since 2008, our group, in cooperation with colleagues from Germany, Italy, Russia, Poland, Belgium, and Iceland, has been deeply involved in overcoming this challenge, by more deeply studying the X-ray physics underlying Computed Tomography: we developed increasingly mature methods to retrieve, from the grey value-defined voxel characteristics given in CT images, the actually underlying physical property, called X-ray attenuation coefficient. The latter contains information on the chemical composition of the material making up the considered voxel, and combining this information with known chemical characteristics of the material class making up the scanned object, gives access to important microstructural information inside the voxel, such as microporosity, or contents of known chemical substances. The latter then enter, as input values, experimentally validated micromechanical formulations representing the material inside the voxel, so as to reliably determine the voxel’s mechanical properties. Corresponding CT-to-mechanics conversion schemes will be presented in appropriate detail, with applications ranging from various ceramics and polymer-ceramic composites used in tissue engineering, to organs made up of the natural material bone.

Abstract

This report describes how an aircraft creates and flies its User Preferred Trajectory from take-off to landing, based on the objectives and constraints the aircraft is subjected to from a technological and operational viewpoint. A basic description of commercial aircraft operation is given, with an emphasis on identifying the different stakeholders (Air Navigation Service Providers, Airline Operation Center, Pilot/Aircraft, Airport and Civil Aviation Authority). A general description of Instrument Flight Rules operations is also given, together with an explanation of the capabilities of modern flight management systems. The objectives and constraints of the trajectory building process from an aircraft and air traffic management viewpoint are described in Chapter 4. Those are instrumental in understanding how the user preferred trajectory is built. The initial and detail route planning process is then described. The initial route planning is performed long before the flight and usually by the airline operating center, while detail flight planning, including take-off, runway and departure procedure is performed later by the crew. This process is re-performed minutes before take-off, and usually iterated during the flight when the details of approach and landing are communicated to the aircraft crew. The implementation of this user preferred trajectory is explained in terms of the options that the pilots have in the aircraft avionics to perform the mission. The implementation explained in this report is based on the avionics suite of a Boeing 737NG aircraft equipped with the most advanced flight management systems. An implementation of a user preferred trajectory, where the aircraft crew is able to best fulfill their objectives is composed of an idle or near idle descent from the cruise altitude. This type of descent, called an advanced continuous descent approach has been implemented by some air navigation service providers, airlines and airports, based on advanced technology that will be further described in this paper. Those procedures are called Green Approaches. In the last part of this report, the benefits of flying Green Approach procedures are analyzed by means of aircraft simulations. The analysis describes in detail the lateral and vertical trajectories of the Green Approaches at Stockholm’s Arlanda Airport and Brisbane Airport (Australia), together with the calculated advantages in term of fuel consumption, noise and gas emissions. QC 20101119