Modal couping effects in the free vibration of elastically interconnected beams

The problem of free vibration of a uniform beam elastically interconnected to a cantilevered beam, representing an idealized launch vehicle aeroelastic model in a wind tunnel, is studied. With elementary beam theory modelling, numerical results are obtained for the frequencies, mode shapes and the generalized modal mass of this elastically cou pled13; system, for a range of values of the spring constants and cantilevered beam stiffness and inertia values. The study shows that when the linear springs are supported at the nodal points corresponding to the first free-free beam mode, the modal interaction comes primarily from the rotational spring stiffness. The effect of the linear spring stiffness on the higher model modes is also found to be marginal. However, the rotational stiffness has a significant effect on all the predominantly model modes as it couples the model13; deformations and the support rod deformations. The study also shows that though the variations in the stiffness or the inertia values of the cantilever beam affect only the13; predominantly cantilever modes, these variations become important because of the fact that the cantilevered support rod frequencies may come close to, or even cross over, the13; predominantly model mode frequencies. The results also bring out the fact that shifting of the support points away from the first mode nodal points has a maximum effect only on the first model mode

Analysis of axisymmetric laminated composite shells subjected to asymmetric loading

A finite element formulation for the static analysis of a laminated composite shell of revolution with general meridional curvature, subjected to asymmetric loading, is presented. The analysis uses an axisymmetric laminated shell element where the shell geometry is satisfactorily represented; higher order polynomial approximations are used for the displacement fields. The asymmetric loading problem is handled through a Fourier series representation of the applied loads and the resultant displacements. Solutions are presented for typical aerospace shell structures like a composite cone and a tangent ogive shell subjected to wind loads

Downlink Performance of Superimposed Pilots in Massive MIMO systems

In this paper, we investigate the downlink throughput performance of a massive multiple-input multiple-output (MIMO) system that employs superimposed pilots for channel estimation. The component of downlink (DL) interference that results from transmitting data alongside pilots in the uplink (UL) is shown to decrease at a rate proportional to the square root of the number of antennas at the BS. The normalized mean-squared error (NMSE) of the channel estimate is compared with the Bayesian Cram\'{e}r-Rao lower bound that is derived for the system, and the former is also shown to diminish with increasing number of antennas at the base station (BS). Furthermore, we show that staggered pilots are a particular case of superimposed pilots and offer the downlink throughput of superimposed pilots while retaining the UL spectral and energy efficiency of regular pilots. We also extend the framework for designing a hybrid system, consisting of users that transmit either regular or superimposed pilots, to minimize both the UL and DL interference. The improved NMSE and DL rates of the channel estimator based on superimposed pilots are demonstrated by means of simulations.Comment: 28 single-column pages, 6 figures, 1 table, Submitted to IEEE Trans. Wireless Commun. in Aug 2017. Revised Submission in Feb. 201

The Abuse of Animals as a Method of Domestic Violence: The Need for Criminalization

A substantial amount of research in recent decades has focused on the relationship between domestic violence and animal abuse. This research has shown that an abusive household often contains more than one victim, and that an abuser is likely to harm both his intimate partner and domestic animals in the home. The bulk of this research has focused on the degree to which these forms of abuse co-occur, the predictive utility of these statistics, and the effect that animal abuse has on a victim\u27s decision to leave the abusive household. Research findings in these areas have spawned a number of efforts to build upon this link to protect both humans and animals, such as including animals in protective orders, encouraging women\u27s shelters to accommodate companion animals, requiring cross-reporting between animal welfare and domestic agencies, and educating the public as to the potential risk implicated by an animal abuser in the home