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Vecchi F.,University of Pavia | Vecchi F.,Instituto Universitario Of Studi Superiori Of Pavia | Bozzola S.,University of Pavia | Pozzoni M.,STMicroelectronics | And 6 more authors.
Digest of Technical Papers - IEEE International Solid-State Circuits Conference | Year: 2010

Multi-Gb/s wireless communications, allocated in the unlicensed spectrum around 60GHz, have been the topic of intense research in the recent past and devices are expected to hit the market shortly. Key aspects behind the increasing interest for technology deployment are the feasibility of the radio in scaled CMOS and the successful demonstration of Gb/s transmissions [1]. Despite the fact that several circuit techniques at mm-Waves have been introduced in the public literature, key aspects of the analog processing tailored to the application requirements need to be addressed. Four channels covering 57GHz to 66GHz are specified [2]. Considering spreads due to process variation, an ultra-wide RF bandwidth of more than ∼12GHz has to be covered with fine sensitivity. In order to allow high-end rate transmissions, the phase noise of the reference signal is extremely stringent. Furthermore, low power consumption is key to enabling multiple transceivers on the same chip. ©2010 IEEE. Source


Iakovlev S.,Dalhousie University | Buchner C.,Vienna University of Technology | Thompson B.,Dalhousie University | Lefieux A.,Instituto Universitario Of Studi Superiori Of Pavia
Journal of Fluids and Structures | Year: 2014

A submerged fluid-filled cylindrical shell subjected to a sequence of two shock waves originated at the same source is considered. It is demonstrated that, unlike in the case of a submerged evacuated shell, there exists a certain critical range of the values of the delay between the incident wavefronts where both the peak compressive and the peak tensile stress observed in the structure are significantly (60% or more) higher than the respective stresses in the same system subjected to a single-front loading. It is further demonstrated that the highest and the lowest hydrodynamic pressure attained in the system is also dramatically affected for certain values of the delay between the incident wavefronts, with the maximum double-front pressure being more than 30% higher than its single-front counterpart. The practical relevance of the findings is discussed in the context of the pre-design analysis of industrial systems subjected to shock loading. © 2014 Elsevier Ltd. Source


Iakovlev S.,Dalhousie University | Mitchell M.,Dalhousie University | Lefieux A.,Instituto Universitario Of Studi Superiori Of Pavia | Murray R.,Dalhousie University
Computers and Fluids | Year: 2014

A submerged fluid-filled cylindrical shell containing a rigid co-axial core and subjected to an external shock wave is considered, and the fluid dynamics of such interaction is analyzed for the most general scenario of two different fluids. It is demonstrated that the phenomenology of the interaction in this case is fundamentally different from the case when the fluids are identical. In the latter case, all the most important wave propagation, reflection and focusing phenomena in the internal fluid that are observed for the shell without a core are also present when a core is placed inside the fluid, unless the core directly occupies the region of the fluid where the phenomena occur. When the fluids are different, however, it is possible that some phenomena are not observed even when the core does not occupy the respective region of the fluid. Due to the very high pressure that is often associated with the phenomena in question, this observation is of considerable practical significance in that it suggests the possibility of a very significant reduction of the peak pressure in the system by means of placing an additional structure inside the primary shell. The observations made are quantified using a number of pressure time-histories aimed at facilitating the pre-design analysis of shock-subjected fluid-interacting structures. © 2014 Elsevier Ltd. Source


Iakovlev S.,Dalhousie University | Buchner C.,Vienna University of Technology | Thompson B.,Dalhousie University | Lefieux A.,Instituto Universitario Of Studi Superiori Of Pavia
11th World Congress on Computational Mechanics, WCCM 2014, 5th European Conference on Computational Mechanics, ECCM 2014 and 6th European Conference on Computational Fluid Dynamics, ECFD 2014 | Year: 2014

We consider the interaction between a sequence of two shock waves and a cylindrical shell submerged into and filled with fluid. The focus of our study is on determining the effect that such a two-front loading has on the extremities of the stress state and the peak hydrodynamic pressure observed in the system, with the ultimate goal of providing the practitioner with the information that could be used at the pre-design stage in determining the most and least dangerous loading conditions for fluid-contacting industrial structures subjected to shock loading. Source


Iakovlev S.,Dalhousie University | Furey C.,Dalhousie University | Pyke D.,Dalhousie University | Lefieux A.,Instituto Universitario Of Studi Superiori Of Pavia
Journal of Fluids and Structures | Year: 2015

The shock response of a submerged system consisting of two co-axial cylindrical shells coupled with the fluid filling the inter-shell space is considered. The shock-structure interaction is modeled using a semi-analytical methodology based on the use of the classical apparatus of mathematical physics. Both the fluid and structural dynamics of the interaction is addressed, with special attention paid to the interplay between the two. It is demonstrated that the wave effects due to multiple reflections of the pressure waves travelling in the inter-shell fluid to a large degree determine the structural dynamics of the system, but have a more pronounced effect on the outer shell than on the inner one. It is also established that the effect of changing the thickness of the outer shell on the stress-strain state of the inner shell is incomparably more pronounced than vice versa. The investigation culminates with the results of a parametric study of the overall peak stress in the system, an example of utilizing the approach developed based on the introduced model and aiming at facilitating structural optimization of industrial systems at the pre-design stage in the context of shock resistance. © 2015 Elsevier Ltd. Source

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