Design and manufacturing of a Selective Laser Sintering test bench to test sintering materials

The goal of this project is to design and build a prototype of recoating system for a laser cutting machine to turn it into a selective laser sintering printing machine. This prototype will be used to study new sintering materials and to design, if decided, a SLS 3D printing Machine (Selective Laser Sintering). This project has been developed in the installations and funded by Fundació CIM. The project develops the mechanical design and the electronic system design. Both parts are explained on this paper, so new users can use the machine and can understand the system. With this paper, it is expected that it can be improved in a future to test other parameters and configurations. The paper is divided in three basic blocks that are summed up here: The first block is an introduction to the 3D printing technologies. The most used of them are explained and selective laser sintering is explained in deep. With this block the reader can understand why it is important to develop the SLS technology and what has to be done to improve the machines and the technology. The second block is a discussion on the mechanical design of the machine. The general idea of the machine is explained so the user can understand why the machine is designed in this way. After that, each part is detailed to see how the different mechanical challenges where overtaken. At the end of the block, there is a small calculations section needed on the electronic part. The third block is an extensive explanation of the electronic system that controls and moves the machine. In that block, the different components are explained so the user can understand its basics working principles. It is also explained how the selection of the electronic components was done. Then everything is put together to see the whole electronic system. Along with this paper, there are annexes that provide some extra information for the reader. One of this annexes refers to the mechanical part and the other one has some datasheets and coding for the electronic section. The whole design has been done in SOLIDWORKS cad software and its electric extension ELECWORKS. The programming job was done with Arduino compiler

Aircraft turning ground maneuvers

In this project a fully parameterized mathematical model of an aircraft turning on the ground in order to get the maximum aircraft speed and minimum infrastructure taxiway radius for three different types of aircrafts (A320, A380 and B737) is developed. The mathematical model takes the form of a system of coupled ordinary differential equations (ODEs). The airframe is considered as a rigid body with six DOF and the equations of motion are derived by balancing the respective forces and moments. Other formulas as Newton’s second law, centripetal equations, friction formulas and other equations will be used to calculate the safest velocity depending on the radius of the taxiway curvature. The software Matlab will be used so as to make all the calculations and will enable us to change the parameters such as mass, friction or radius to find new velocities according to the aircraft. Moreover, the use of Microsoft Excel software to insert those results already found in Matlab and create new tables depending on the radius and ground weather conditions (dry or wet). The results show that each aircraft has a different safety velocity although they turn with the same taxiway radius. There is also a bibliographic and modelling work explaining how to get all the equations and the different types of taxiway entries

Symplectic Instanton Homology: naturality, and maps from cobordisms

We prove that Manolescu and Woodward's Symplectic Instanton homology, and its twisted versions are natural, and define maps associated to four dimensional cobordisms within this theory. This allows one to define representations of the mapping class group and the fundamental group of a 3-manifold, and to have a geometric interpretation of the maps appearing in the long exact sequence for symplectic instanton homology, together with vanishing criterions.Comment: 37 pages, 11 figures. Proof of naturality thoroughly revised. To appear in Quantum Topolog

A pruned dynamic programming algorithm to recover the best segmentations with 11 to KmaxK_{max} change-points

A common computational problem in multiple change-point models is to recover the segmentations with $1$ to $K_{max}$ change-points of minimal cost with respect to some loss function. Here we present an algorithm to prune the set of candidate change-points which is based on a functional representation of the cost of segmentations. We study the worst case complexity of the algorithm when there is a unidimensional parameter per segment and demonstrate that it is at worst equivalent to the complexity of the segment neighbourhood algorithm: $\mathcal{O}(K_{max} n^2)$. For a particular loss function we demonstrate that pruning is on average efficient even if there are no change-points in the signal. Finally, we empirically study the performance of the algorithm in the case of the quadratic loss and show that it is faster than the segment neighbourhood algorithm.Comment: 31 pages, An extended version of the pre-prin

Cost-containment in health care: The case of Spain from the eighties up to 1997

The purpose of this paper is to provide an overview of the evolution of health care expenditure in Spain during the period 1980-1997, and henceforth to comment on the cost containment measures put forward to control its growth. The paper is divided into three separate sections. The first offers a brief description of the Spanish Health Care System, with emphasis placed on the issue of expenditure control and health planning targets. The second part outlines a set of cost containment measures that has accompanied the process of extending universal health care coverage which occurred during the mentioned period and which has helped keep public expenditure under control. Finally, the third part describes some of the more recent proposals for reform of the Spanish Health Care Sector.Cost containment, health care, the spanish NHS, health economics

Tetramorium Parvioculum Sp. N. (FORMICIDAE: MYRMICINAE), A new species of the T. Simillimum group from Gibraltar

We describe a new species of Tetramorium, which has so far only been found in Gibraltar. Tetramorium parvioculum sp. n. belongs to the simillimum-group, which is of Afrotropical origin. It is likely that this species is a non native and was imported with plant material originating from tropical Africa. The ecology of this new species is discussed