Design and performance analysis study of an ion thruster

Desenvolupar l'estudi preliminar d'un dispositiu propulsor elèctric de tipus iònic per a un vehicle espacial.1. Introducció.2. Anàlisi de missió, incloent càlcul de trajectòries i/o maniobres orbitals típiques, amb un cert grau de detall.3. Justificació del motor iònic com a sistema propulsor adequat per a la missió en particular, a partir d'una anàlisi comparativa de diferents tipus de propulsors per a vehicles espacials, tot assenyalant els avantatges i inconvenients de cadascun d'ells.4. Breu introducció a la física de plasmes magnetitzats.5. Anàlisi preliminar d'un propulsor iònic, mitjançant mètodes analítics simplificats.6. Anàlisi numèrica mitjançant un model quasi-unidimensional, fent ús de la teoria de Brophy.7. Validació dels resultats, per comparació amb altres models numèrics i/o resultats d'assaigs experimentals.8. Anàlisi d'actuacions per diferents condicions d'operació.9. Conclusions

A new type of pump turbine system specially developed for reverse osmosis application

A n ew type of pump has been developed specially suitable for reverse osmosis applications. The hydrodynamic theory of the pumps is given as well as some mechanical calculations typical of these p u m p s. Finally, the experimental performances of a number of working models arq - shown. A very short comment is also included on the feasibility of - utilizing a combined turbo-pump group of this type for energy recovery in reverse osmosis desalination plant

Bill Viola’s 'Nantes Triptych': Unearthing the sources of its condensed temporality

In this text we intend to analyze Bill Viola’s video installation Nantes Triptych (1992) as an example of the richness which lies in the liminal spaces between arts. We defend the thesis that the utilization of the traditional pictorial structure of the triptych in this particular work, along with the powerful audiovisual material, renders a kairological event available to the viewer. This temporal experience makes possible an existential experience when in front of this video installation. To discuss this assumption we will use classical art theory texts about the triptychs, as well as, among others, Deleuze’s texts about time image and the triptych structure, Agamben’s concept of kairos, the concept of kairological artwork coined by David Chan and the philosophy of temporality developed by Merleau-Ponty

Higgs and new physics at high energy

The observation of a new particle in the search for the Standard Model (SM) Higgs boson at the LHC, reported by the ATLAS and CMS collaborations, is a milestone in the quest to understand electroweak symmetry breaking. The evidence at the level of 5 $\sigma$ for a Higgs boson-like particle has been published by both experiments after a preliminary analysis of the data from the LHC Run-I. Precision measurements of the new particle are of critical importance. This document reviews the mass and spin measurement, the couplings scale factor measurements and the limits on new physics derived from these results.Comment: Presented at the 2014 Flavor Physics and CP Violation (FPCP-2014), Marseille, France, May 26-30 2014, 9 pages, 9 figure

Degenerate parametric oscillation in quantum membrane optomechanics

The promise of innovative applications has triggered the development of many modern technologies capable of exploiting quantum effects. But in addition to future applications, such quantum technologies have already provided us with the possibility of accessing quantum-mechanical scenarios that seemed unreachable just a few decades ago. With this spirit, in this work we show that modern optomechanical setups are mature enough to implement one of the most elusive models in the field of open system dynamics: degenerate parametric oscillation. The possibility of implementing it in nonlinear optical resonators was the main motivation for introducing such model in the eighties, which rapidly became a paradigm for the study of dissipative phase transitions whose corresponding spontaneously broken symmetry is discrete. However, it was found that the intrinsic multimode nature of optical cavities makes it impossible to experimentally study the model all the way through its phase transition. In contrast, here we show that this long-awaited model can be implemented in the motion of a mechanical object dispersively coupled to the light contained in a cavity, when the latter is properly driven with multi-chromatic laser light. We focus on membranes as the mechanical element, showing that the main signatures of the degenerate parametric oscillation model can be studied in state-of-the-art setups, thus opening the possibility of studying spontaneous symmetry breaking and enhanced metrology in one of the cleanest dissipative phase transitions.Comment: We welcome comments, suggestions, and (constructive) criticis

Photon correlation spectroscopy as a witness for quantum coherence

The development of spectroscopic techniques able to detect and verify quantum coherence is a goal of increasing importance given the rapid progress of new quantum technologies, the advances in the field of quantum thermodynamics, and the emergence of new questions in chemistry and biology regarding the possible relevance of quantum coherence in biochemical processes. Ideally, these tools should be able to detect and verify the presence of quantum coherence in both the transient dynamics and the steady state of driven-dissipative systems, such as light-harvesting complexes driven by thermal photons in natural conditions. This requirement poses a challenge for standard laser spectroscopy methods. Here, we propose photon correlation measurements as a new tool to analyse quantum dynamics in molecular aggregates in driven-dissipative situations. We show that the photon correlation statistics on the light emitted by a molecular dimer model can signal the presence of coherent dynamics. Deviations from the counting statistics of independent emitters constitute a direct fingerprint of quantum coherence in the steady state. Furthermore, the analysis of frequency resolved photon correlations can signal the presence of coherent dynamics even in the absence of steady state coherence, providing direct spectroscopic access to the much sought-after site energies in molecular aggregates

Temperature modelling and model predictive control of a pilot-scale batch reaction system

The temperature control equipment on a pilot scale batch reaction system located at EAFIT University in Medelln, Colombia, is modeled and a new controller is designed aiming at using it in the reactor current PLC-based control system. Some mathematical models are developed from experimental data to describe the system behavior and using them several model based predictive controllers are designed. The simplest, yet reliable, model obtained is an ARX polynomial model of order (1,1,1) that yields a four states ane model for which an explicit MPC was calculated. This controller has a reduced mathematical complexity and can probably be used directly on the existing control system.Preprin

Rank diversity of languages: Generic behavior in computational linguistics

Statistical studies of languages have focused on the rank-frequency distribution of words. Instead, we introduce here a measure of how word ranks change in time and call this distribution \emph{rank diversity}. We calculate this diversity for books published in six European languages since 1800, and find that it follows a universal lognormal distribution. Based on the mean and standard deviation associated with the lognormal distribution, we define three different word regimes of languages: "heads" consist of words which almost do not change their rank in time, "bodies" are words of general use, while "tails" are comprised by context-specific words and vary their rank considerably in time. The heads and bodies reflect the size of language cores identified by linguists for basic communication. We propose a Gaussian random walk model which reproduces the rank variation of words in time and thus the diversity. Rank diversity of words can be understood as the result of random variations in rank, where the size of the variation depends on the rank itself. We find that the core size is similar for all languages studied