Repository UNSAP (Universitas Sebelas April)
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Toward 30-gram Autonomous Indoor Aircraft: Vision-based Obstacle Avoidance and Altitude Control
No full textWe aim at developing autonomous micro-flyers capable of navigating within houses or small built environments. The severe weight and energy constraints of indoor flying platforms led us to take inspiration from flying insects for the selection of sensors, signal processing, and behaviors. This paper presents the control strategies enabling obstacle avoidance and altitude control using only optic flow and gyroscopic information. For experimental convenience, the control strategies are first implemented and tested separately on a small wheeled robot featuring the same hardware as the targeted aircraft. The obstacle avoidance system is then transferred to a 30-gram aircraft, which demonstrates autonomous steering within a square textured arena.LISSponsor: Swiss National Science Foundatio
Silicon nitride waveguide or photonic integrated circuit fabrication method
No full textSilicon nitride waveguide fabrication method including providing a substrate including a stress release trench structure, the stress release recess structure being formed in a silicon oxide layer, depositing a silicon nitride material or layer onto the silicon oxide layer, providing a silicon oxide hard mask on the deposited silicon nitride material or layer to provide an exposed surface delimited by the silicon oxide hard mask and defined by the deposited silicon nitride material or layer, the silicon oxide hard mask including or defining an elongation extending on the deposited silicon nitride material or layer, dry etching the exposed surface a silicon nitride elongated waveguide core located between the silicon oxide hard mask and the silicon oxide layer in which the stress release trench structure is formed; and depositing a silicon oxide cladding layer on the silicon oxide hard mask to form a cladding structure of the silicon nitride waveguide.AVP-R-TTOAlternative title(s) :
(fr) Guide d'ondes de nitrure de silicium ou procédé de fabrication de circuit intégré photoniqu
Simulación numérica de turbinas Francis
No full textEste libro aborda el panorama de la simulación numérica de turbinas Francis desde un punto de vista tanto estacionario como transitorio. Por primera vez se describe la metodología de simulación de escenarios de funcionamiento desfavorables de la máquina, lo cual es una novedad en el campo de la simulación de turbo-máquinas hidráulicas.LM
Au port de Chevroux (Vaud). Un centre nature et une pisciculture
No full textSAR-DCRECote: 1998.032Archive: MEM.1/1A4 horizontal, DES1.0/6microfiches, MAV cassette audioGroupe de suivi: Cantàfora Arduino; Zurbuchen Bernard; Décosterd Jean-Gille
Numerical analysis of seasonal heat storage in an energy pile foundation
No full textThe use of concrete geostructures for energy extraction and storage in the ground is an environmentally friendly and easy way of cooling and heating buildings. With such energy geostructures, it is possible to transfer energy from the ground to buildings by means of fluid-filled pipes cast in concrete. By injecting thermal energy in summer and extracting it in winter, the ground in the area of a building’s piles can be used for seasonal energy storage, as long as the underground water flow in the storage remains low. This paper is a contribution to the improvement of the knowledge in the field of energy geostructures. The behaviour of a multi-pile seasonal storage system subjected to thermo-mechanical loading is examined numerically from both thermal and mechanical perspectives. The purpose of this paper is (i) to propose a thermo-hydro-mechanical 2D solution to the 3D problem, (ii) to explore the thermal behaviour of this type of storage and (iii) to evaluate its structural consequences. Coupled multi-physical finite element modelling is conducted. The efficiency of the storage is not dramatically affected by an increase in the annual mean temperature of the storage. It is shown that induced mechanical loads are less important when considering a wholly heated pile structure than when considering a single heated pile in a foundation. The evolution of stresses in the piles and in the soil during heating–cooling cycles also reveals possible critical phenomena.LM
Resistivity Characteristics and Noise Spectroscopy of Composites with Carbon Fiber Felts
No full textICLA
Rate Performance Objectives of Multi-hop Wireless Networks
No full textWe consider the question of what performance metric to maximize when designing adhoc wireless network protocols such as routing or MAC. We focus on maximizing rates under battery lifetime and power constraints. Commonly used metrics are total capacity (in the case of cellular networks) and transport capacity (in the case of adhoc networks). However, it is known in traditional wired networking that maximizing total capacity conflicts with fairness, and this is why fairness oriented rate allocations, such as max-min fairness, are often used. We review this issue for wireless ad-hoc networks. Indeed, the mathematical model for wireless networks has a specificity that makes some of the findings different. It has been reported in the literature on Ultra Wide Band that gross unfairness occurs when maximizing total capacity or transport capacity, and we confirm by a theoretical analysis that this is a fundamental shortcoming of such metrics in wireless ad-hoc networks, as it is for wired networks. The story is different for max-min fairness. Although it is perfectly viable for a wired network, it is much less so in our setting. We show that, in the limit of long battery lifetime, the max-min allocation of rates always leads to strictly equal rates, regardless of the MAC layer, network topology, choice of routes and power constraints. This is due to the ``solidarityLCALCA
Preprocessing among the Infalling Galaxy Population of EDisCS Clusters
No full textWe present results from a low-resolution spectroscopic survey for 21 galaxy clusters at 0.4 < z < 0.8 selected from the ESO Distant Cluster Survey. We measured spectra using the low-dispersion prism in IMACS on the Magellan Baade telescope and calculate redshifts with an accuracy of sigma(z) = 0.007. We find 1763 galaxies that are brighter than R = 22.9 in the large-scale cluster environs. We identify the galaxies expected to be accreted by the clusters as they evolve to z = 0 using spherical infall models and find that similar to 30%-70% of the z = 0 cluster population lies outside the virial radius at z similar to 0.6. For analogous clusters at z = 0, we calculate that the ratio of galaxies that have fallen into the clusters since z similar to 0.6 to those that were already in the core at that redshift is typically between similar to 0.3 and 1.5. This wide range of ratios is due to intrinsic scatter and is not a function of velocity dispersion, so a variety of infall histories is to be expected for clusters with current velocity dispersions of 300 km s(-1) less than or similar to sigma less than or similar to 1200 km s(-1). Within the infall regions of z similar to 0.6 clusters, we find a larger red fraction of galaxies than in the field and greater clustering among red galaxies than blue. We interpret these findings as evidence of "preprocessing," where galaxies in denser local environments have their star formation rates affected prior to their aggregation into massive clusters, although the possibility of backsplash galaxies complicates the interpretation.LASTR
Pattern recognition in two-dimensional NMR spectra
No full textThe use of sign alteration of cross-peak multiplet patterns in phase-sensitive 2-dimensional spectral pattern recognition is discussed. Illustrative results on 2,3-dibromopropionic acid are presented. [on SciFinder (R)]LRM