Design and development of a smart panel with five decentralised control units for the reduction of vibration and sound radiation

This Technical Report discusses the design and the construction of a smart panel with five decentralised direct velocity feedback control units in order to reduce the vibration of the panel dominated by well separated low frequency resonances. Each control unit consists of an accelerometer sensor and a piezoelectric patch strain actuator. The integrated accelerometer signal is fed back to the actuator via a fixed negative control gain. In this way the actuator generates a control excitation proportional and opposite to the measured transverse velocity of the panel so that it produces active damping on the panel. First the open loop frequency response function between the sensor and the actuator of a single channel has been studied and an analogue controller has been designed and tested in order to improve the stability of this control system. Following the stability of all five control units has been assessed using the generalised Nyquist criterion. Finally the performances of the smart panel have been tested with reference to the reduction of the vibrations at the error positions and with reference to the reduction of the radiated sound. Finally in appendix to this Report, a parametric study is presented on the properties of sensor-actuator FRFs measured with different types of piezoelectric patch actuators. The results of this parametric study have been used in order to choose the actuators to be used for the construction of the smart pane

A Fast Chi-squared Technique For Period Search of Irregularly Sampled Data

A new, computationally- and statistically-efficient algorithm, the Fast $\chi^2$ algorithm, can find a periodic signal with harmonic content in irregularly-sampled data with non-uniform errors. The algorithm calculates the minimized $\chi^2$ as a function of frequency at the desired number of harmonics, using Fast Fourier Transforms to provide $O (N \log N)$ performance. The code for a reference implementation is provided.Comment: Source code for the reference implementation is available at http://public.lanl.gov/palmer/fastchi.html . Accepted by ApJ. 24 pages, 4 figure

The ECLAIRs telescope onboard the SVOM mission for gamma-ray burst studies

The X- and gamma-ray telescope ECLAIRs onboard the future mission for gamma-ray burst studies SVOM (Space-based multi-band astronomical Variable Objects Monitor) is foreseen to operate in orbit from 2013 on. ECLAIRs will provide fast and accurate GRB triggers to other onboard telescopes, as well as to the whole GRB community, in particular ground-based follow-up telescopes. With its very low energy threshold ECLAIRs is particularly well suited for the detection of highly redshifted GRB. The ECLAIRs X- and gamma-ray imaging camera (CXG), used for GRB detection and localization, is combined with a soft X-ray telescope (SXT) for afterglow observations and position refinement. The CXG is a 2D-coded mask imager with a 1024 cm$^2$ detection plane made of 80$\times$80 CdTe pixels, sensitive from 4 to 300 keV, with imaging capabilities up to about 120 keV and a localization accuracy better than 10 arcmin. The CXG permanently observes a 2 sr-wide field of the sky and provides photon data to the onboard science and triggering unit (UTS) which detects GRB by count-rate increases or by the appearance of a new source in cyclic sky images. The SXT is a mirror focusing X-ray telescope operating from 0.3 to 2 keV with a sensitivity of 1 mCrab for 100 s observations. The spacecraft slews within $\simeq$3 min in order to place the GRB candidate into the 23$\times$23 arcmin$^2$ field of view of the SXT, after which it refines the GRB position to about 10 arcsec. GRB alerts are transmitted to ground-observers within tens of seconds via a VHF network and all detected photons are available hours later for detailed analysis. In this paper we present the ECLAIRs concepts, with emphasis on the expected performances.Comment: on behalf of the ECLAIRs collaboration. Proceedings of Gamma-Ray Bursts 2007 conference, Santa Fe, USA, 5-9 November 2007. Published in AIP conf. proc. 1000, 581-584 (2008

Strong spectral evolution during the prompt emission of GRB 070616

Swift has revealed features in GRB early light curves, such as steep decays and X-ray flares, whose properties are consistent with an internal origin though they are far from understood. The steep X-ray decay is often explained using the curvature effect; however a significant number of GRBs display strong spectral evolution during this phase, and a new mechanism must be invoked to explain this. Of particular interest are the longest duration GRBs in which the early emission can be studied in most detail. Here we present data for GRB 070616, in which the prompt emission shows a complex multipeaked structure, leading to one of the longest prompt emission durations ever recorded. We take advantage of extensive coverage of such a long burst by all Swift instruments. Combining data from Swift and Suzaku we study the evolution of the prompt emission spectrum, following the temporal variability of the peak energy and spectral slope.Comment: 4 pages, 2 figures (Fig 1 in colour), contributed talk, submitted to the proceedings of Gamma Ray Bursts 2007, Santa Fe, New Mexico, November 5-9 200

GRB-triggered searches for gravitational waves in LIGO data

The LIGO gravitational wave detectors have recently reached their design sensitivity and finished a two-year science run. During this period one year of data with unprecedented sensitivity has been collected. I will briefly describe the status of the LIGO detectors and the overall quality of the most recent science run. I also will present results of a search for inspiral waveforms in gravitational wave data coincident with the short gamma ray burst detected on 1st February 2007, with its sky location error box overlapping a spiral arms of M31. No gravitational wave signals were detected and a binary merger in M31 can be excluded at the 99% confidence level.Comment: 5 pages, 3 figures, contributed talk, submitted to the proceedings of Gamma Ray Bursts 2007, Santa Fe, New Mexico, November 5-9 200

Diversity, Recognition, Respect: Embedding Indigenous Services at the State Library of New South Wales, Australia

The State Library of New South Wales (NSW) holds significant collections of material relating to the history and experiences of Indigenous people in Australia. These collections are a vital resource for Indigenous people and communities, particularly in relation to language and cultural revitalisation. As Australia’s oldest library, with its origins dating back to 1826, the State Library aims to inform, educate and inspire with the services it provides online, on site and on tour. In 2014, the Library renewed its focus and commitment to Aboriginal and Torres Strait Islander people and communities by establishing a team dedicated to developing Indigenous services for the Library. This paper provides a case study of the Library developing a Business Plan (2014) for Indigenous services. It will describe the research and engagement process undertaken to develop the plan and to progress Indigenous priorities as core business of the Library. The building of long-term and meaningful relationships with Indigenous people and communities, through ongoing consultation will be discussed. Speakers will share information on strategies for embedding Indigenous library services through a respectful recognition of Indigenous culture and history. In doing this the paper will aim to promote a two-way learning process - where libraries can engage in ongoing capacity building for staff to feel competent and empowered

Quantum dynamics of a high-finesse optical cavity coupled with a thin semi-transparent membrane

We study the quantum dynamics of the cavity optomechanical system formed by a Fabry-Perot cavity with a thin vibrating membrane at its center. We first derive the general multimode Hamiltonian describing the radiation pressure interaction between the cavity modes and the vibrational modes of the membrane. We then restrict the analysis to the standard case of a single cavity mode interacting with a single mechanical resonator and we determine to what extent optical absorption by the membrane hinder reaching a quantum regime for the cavity-membrane system. We show that membrane absorption does not pose serious limitations and that one can simultaneously achieve ground state cooling of a vibrational mode of the membrane and stationary optomechanical entanglement with state-of-the-art apparatuses.Comment: 14 pages, 7 figure

Quantum dynamics of a vibrational mode of a membrane within an optical cavity

Optomechanical systems are a promising candidate for the implementation of quantum interfaces for storing and redistributing quantum information. Here we focus on the case of a high-finesse optical cavity with a thin vibrating semitransparent membrane in the middle. We show that robust and stationary optomechanical entanglement could be achieved in the system, even in the presence of nonnegligible optical absorption in the membrane. We also present some preliminary experimental data showing radiation-pressure induced optical bistability.Comment: 6 pages, 2 figures. Work presented at the conference QCMC 2010 held on 19-23 July 2010 at the University of Queensland, Brisbane, Australi

Afterglows of Gamma-Ray Bursts: Short vs. Long GRBs

We compiled a large sample of Swift-era photometric data on long (Type II) and short (Type I) GRB afterglows. We compare the luminosity and energetics of the different samples to each other and to the afterglows of the pre-Swift era. Here, we present the first results of these studies.Comment: Conference Proceedings, "Gamma-Ray Bursts 2007", Santa Fe, shortened poster presentation; 4 pages, 3 figures; for full updated papers, go here to arXiv:0712.2186 and also here to arXiv:0804.195