4,181 research outputs found
Structural dynamics of shroudless, hollow fan blades with composite in-lays
Structural and dynamic analyses are presented for a shroudless, hollow titanium fan blade proposed for future use in aircraft turbine engines. The blade was modeled and analyzed using the composite blade structural analysis computer program (COBSTRAN); an integrated program consisting of mesh generators, composite mechanics codes, NASTRAN, and pre- and post-processors. Vibration and impact analyses are presented. The vibration analysis was conducted with COBSTRAN. Results show the effect of the centrifugal force field on frequencies, twist, and blade camber. Bird impact analysis was performed with the multi-mode blade impact computer program. This program uses the geometric model and modal analysis from the COBSTRAN vibration analysis to determine the gross impact response of the fan blades to bird strikes. The structural performance of this blade is also compared to a blade of similar design but with composite in-lays on the outer surface. Results show that the composite in-lays can be selected (designed) to substantially modify the mechanical performance of the shroudless, hollow fan blade
Visualizing the Quantum Interaction Picture in Phase Space
We illustrate the correspondence between the quantum Interaction
Picture-evolution of the state of a quantum system in Hilbert space and a
combination of local and global transformations of its Wigner function in phase
space. To this aim, we consider the time-evolution of a quantized harmonic
oscillator driven by both a linear and a quadratic (in terms of bosonic
creation and annihilation operators) potentials and employ the Magnus series to
derive the exact form of the time-evolution operator. In this case, the
Interaction Picture corresponds to a local transformation of phase
space-reference frame into the one that is co-moving with the Wigner function.Comment: Submitted to New Journal of Physic
A Protocol for Generating Random Elements with their Probabilities
We give an AM protocol that allows the verifier to sample elements x from a
probability distribution P, which is held by the prover. If the prover is
honest, the verifier outputs (x, P(x)) with probability close to P(x). In case
the prover is dishonest, one may hope for the following guarantee: if the
verifier outputs (x, p), then the probability that the verifier outputs x is
close to p. Simple examples show that this cannot be achieved. Instead, we show
that the following weaker condition holds (in a well defined sense) on average:
If (x, p) is output, then p is an upper bound on the probability that x is
output. Our protocol yields a new transformation to turn interactive proofs
where the verifier uses private random coins into proofs with public coins. The
verifier has better running time compared to the well-known Goldwasser-Sipser
transformation (STOC, 1986). For constant-round protocols, we only lose an
arbitrarily small constant in soundness and completeness, while our public-coin
verifier calls the private-coin verifier only once
VIRTUAL MUSEUMS AS A MEANS FOR PROMOTION AND ENHANCEMENT OF CULTURAL HERITAGE
Abstract. The use of virtual reality and ICT in the museum context provides a new key to understand and promote Cultural Heritage: thanks to these technologies the user has the opportunity to experience without the need to come into contact with the real objects. For the museum institutions VR and ICT are a valuable tool that allows them to perform different cultural tasks, addressing the public in a much more effective way than has previously been possible. Especially through VR, it is possible to reconstruct the original context of the artworks through the interconnection of contents: the virtual visitor, while viewing the artwork, can consult useful contents for the learning process. Another revolutionary element introduced by the new technologies is linked to the possibility of creating virtual exhibitions through which it is possible to exhibit works that are not accessible or not visible. These reflections and these theoretical principles were the basis for the development of the project proposal presented in these pages, that was born as a collaboration between the R3D Lab of the Museo della Rappresentazione of University of Catania and the CIMS Lab of Carleton University, Ottawa. It consists in the creation of a virtual museum, the Timeless Museum, in order to create an educational experience, able to make the users reflect on topics such as the value of history, the sense of beauty, the relationship with our past and our future, the protection and transmission to future generations of the artistic heritage we have.</p
Design of Relaxation Digital-to-Analog Converters for Internet of Things Applications in 40nm CMOS
A 10-bit-400kS/s and a 10-bit-2MS/s Relaxation Digital to Analog Converters (ReDAC) in 40nm are presented in this paper. The two ReDACs operate from a 600mV power supply, occupy a silicon area of less than 1,000um^2. The first/second DAC achieve a maximum INL of 0.33/0.72 LSB and a maximum DNL of 0.2/1.27 LSB and 9.9/9.4 ENOB based on post-layout simulations. The average energy per conversion is less than 1.1/0.73pJ, corresponding to a FOM of 1.1/1.08 fJ/(conv. step), which make them well suited to Internet of Things (IoT) applications. (PDF) Design of Relaxation Digital-to-Analog Converters for Internet of Things Applications in 40nm CMOS. Available from: https://www.researchgate.net/publication/336552301_Design_of_Relaxation_Digital-to-Analog_Converters_for_Internet_of_Things_Applications_in_40nm_CMOS [accessed Nov 16 2019]
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