MEMS-based Speckle Spectrometer

We describe a new concept for a MEMS-based active spatial filter for astronomical spectroscopy. The goal of this device is to allow the use of a diffraction-limited spectrometer on a seeing limited observation at improved throughput over a comparable seeing-limited spectrometer, thus reducing the size and cost of the spectrometer by a factor proportional to r0/D (For the case of a 10 meter telescope this size reduction will be approximately a factor of 25 to 50). We use a fiber-based integral field unit (IFU) that incorporates an active MEMS mirror array to feed an astronomical spectrograph. A fast camera is used in parallel to sense speckle images at a spatial resolution of lambda/D and at a temporal frequency greater than that of atmospheric fluctuations. The MEMS mirror-array is used as an active shutter to feed speckle images above a preset intensity threshold to the spectrometer, thereby increasing the signal-to-noise ratio (SNR) of the spectrogram. Preliminary calculations suggests an SNR improvement of a factor of about 1.4. Computer simulations have shown an SNR improvement of 1.1, but have not yet fully explored the parameter space.Comment: 11 pages, 5 figures, presented at SPIE Astronomical Telescopes and Instrumentation, 24 - 31 May 2006, Orlando, Florida US

The small-scale Structure of the Magellanic Stream as a Foundation for Galaxy Evolution

The Magellanic Stream (MS) is the nearest example of a gaseous trail formed by interacting galaxies. While the substantial gas masses in these kinds of circumgalactic structures are postulated to represent important sources of fuel for future star formation, the mechanisms whereby this material might be accreted back into galaxies remain unclear. Recent neutral hydrogen (HI) observations have demonstrated that the northern portion of the MS, which probably has been interacting with the Milky Way's hot gaseous halo for close to 1000~Myr, has a larger spatial extent than previously recognized, while also containing significant amounts of small-scale structure. After a brief consideration of the large-scale kinematics of the MS as traced by the recently-discovered extension of the MS, we explore the aging process of the MS gas through the operation of various hydrodynamic instabilities and interstellar turbulence. This in turn leads to consideration of processes whereby MS material survives as cool gas, and yet also evidently fails to form stars. Parallels between the MS and extragalactic tidal features are briefly discussed with an emphasis on steps toward establishing what the MS reveals about the critical role of local processes in determining the evolution of these kinds of systems

Patterns of Sustainable Innovation in the Building Industry. Towards a Strategic Management Perspective on Environmental, Social, and Economic Values.

L'abstract è presente nell'allegato / the abstract is in the attachmen

The Fourth-Century AD Expansion of the Graeco-Roman Settlement of Karanis (Kom Aushim) in the Northern Fayum*

The Graeco-Roman town of Karanis, founded during the Ptolemaic Period in the north-eastern Fayum in the third century bc and long thought to have been abandoned in the third century ad actually saw a substantial expansion during the fourth century AD. With the creation of an 3 extension towards the west and the expansion of the eastern part, the town grew in both directions. We argue that this expansion may be related to a sudden rise of the water level in Lake Moeris (Lake Qarun), perhaps linked to a catastrophic dam breach in the eastern part of the Fayum, and the subsequent relocation of the inhabitants of the low-lying settlements north and east of the lake

Integrated approach to sustainable building design programming

This paper aims at analysing the relationship between aesthetic and technological aspects in the design process. ‘Sustainability’ is often a label associated mainly to technological systems aimed at achieving energy efficiency, without considering architectural quality of spaces or environmental and sustainable performances as a holistic approach. Since buildings are working as systems and not as simple sums of elements, this paper proposes an integrated building design methodology, which embeds and merges technological, environmental and esthetical aspects. To this end, the paper presents the design teaching and research experience carried out with the students of final atelier of the Master of Sustainability, at the Polytechnic of Turin in 2014. In this atelier students were asked to design a building for the Architecture Faculty for The University of Melbourne. During this final atelier, a number of tools were applied throughout the overall design development to helps students in developing projects able to integrate aesthetic, environmental and technological aspects. For instance, one of these tools was the site microclimate matrix, which is a valid instrument for precisely defining master plans organizations, or placing volumetric solutions on sites, following a decision making process based on site-specific functional, technological and environmental aspects. This tool, as well as others that were adopted in the atelier, demonstrated to provide students the ability of developing projects characterised by efficient technical solution and high creative architectural designs

A turn-key Concept for active cancellation of Global Positioning System L3 Signal

We present a concept, developed at the National Astronomy and Ionosphere Center (NAIC) at Arecibo, Puerto Rico, for active suppression of Global Positioning System (GPS) signals in the 305 m dish radio receiver path prior to backend processing. The subsystem does not require an auxiliary antenna and is intended for easy integration with radio telescope systems with a goal of being a turnkey addition to virtually any facility. Working with actual sampled signal data, we have focused on the detection and cancellation of the GPS L3 signal at 1381.05 MHz which, during periodic test modes and particularly during system-wide tests, interfere with observations of objects in a range of redshifts that includes the Coma supercluster, for example. This signal can dynamically change modulation modes and our scheme is capable of detecting these changes and applying cancellation or sending a blanking signal, as appropriate. The subsystem can also be adapted to GPS L1 (1575.42 MHz), L2C (1227.6 MHz), and others. A follow-up is underway to develop a prototype to deploy and evaluate at NAIC.Comment: Presented at the RFI mitigation workshop, 29-31 March 2010, Groningen, the Netherlands. Accepted for publication by the Proceedings of Scienc

Nature-inspired optimization of hierarchical porous media for catalytic and separation processes

Hierarchical materials combining pore sizes of different length scales are highly important for catalysis and separation processes, where optimization of adsorption and transport properties is required. Nature can be an excellent guide to rational design, as it is full of hierarchical structures that are intrinsically scaling, efficient and robust. However, much of the “inspiration” from nature is, at present, empirical; considering the huge design space, we advocate a methodical, fundamental approach based on mechanistic features