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Abstract In this paper, the optimal locations of finite number of embedded magneto-rheological fluid (MRF) pockets are calculated by using Single Objective Genetic Algorithm (SOGA) to suppress the supersonic flutter of an elastically supported sandwich beam with regular honeycomb interlayer. The structural formulation is based on the classical beam theory along with the Winkler-Pasternak foundation model, the MRF is modeled as a first order Kelvin-Voigt material, and the quasi-steady first order supersonic piston theory is employed to define the aerodynamic loading. The aeroelastic time response of honeycomb sandwich beams with different number of embedded MRF pockets are measured with/without foundation and flow stream under impact load. The simulation shows that by using MRF pockets in optimized locations in honeycomb sandwich structure, not only both lightness of honeycombs and variability of structural damping of MRF are considered, but also the supersonic flutter can be postponed to higher dynamic pressure compared to entirely honeycomb or MRF sandwich beams. Finally, in order to achieve the optimum compromise between mass and the flutter suppression, the best number of MR pockets along with the optimum magnetic field values in honeycomb sandwich structure is presented. Highlights • First order Kelvin-Voigt viscoelastic theory is employed to model the behavior of the magneto-rheological material. • Locations of the MR pockets are optimized by Genetic Algorithm to improve vibrational characteristics of the structure. • Supersonic flutter suppression is remarkably obtained by MR pockets. [ABSTRACT FROM AUTHOR]

In this paper, by using the piezoelectric material, the active aeroelastic flutter characteristics and vibration control of supersonic sandwich panels with different honeycomb interlayers, resting on an elastic foundation, are studied. Classical beam theory along with the Winkler-Pasternak foundation model, and the quasi-steady first order supersonic piston theory are employed in the formulation of the structural theory and aerodynamic loading, respectively. Hamilton's principle in conjunction with the generalized Fourier expansions and Rayleigh-Ritz (RR) method are used to develop the dynamical model of the structural systems in the state-space domain. The aeroelastic flutter bounds are obtained via the p-method. The classical Runge-Kutta integration algorithm is then used to calculate the open-loop aeroelastic response of the system under different loading excitations. Finally, two classical control strategies, including direct proportional feedback and linear-quadratic regulator (LQR) optimal control scheme, are used to actively suppress the closed loop system response, while increasing the flutter aerodynamic pressure. [ABSTRACT FROM AUTHOR]

Appropriate conformal mapping transformation in combination with the linear potential theory is employed to develop mathematical model for two-dimensional sloshing in horizontal circular cylindrical containers with overall eccentric hole. The tube-type tank is filled with inviscid incompressible fluid up to its half depth and subjected to lateral accelerations. A ramp-step excitation encountered in a road turning maneuver as well as real seismic event is used to simulate the lateral acceleration excitation. The resulting linear sets of ordinary differential equations are truncated and then solved numerically by employing Laplace transform technique followed by Durbin's numerical inversion pattern. The effects of excitation input time, eccentricity, and radii ratio on the hydrodynamic responses and suppression of the induced destabilizing lateral forces are examined. Limiting cases are considered and good agreements with available analytic and numerical solutions as well as the simulations performed by using a commercial FEM software package are obtained. [ABSTRACT FROM AUTHOR]

In this paper, free vibration analysis of truncated sandwich conical shells with the magnetorheological (MR) core is investigated. The mathematical modeling of the shell is performed based on the first-order shear deformation theory (FSDT) and the set of the governing equations and associated boundary conditions are derived utilizing Hamilton's principle. A semi-analytical solution is provided for various boundary conditions through an exact solution in the circumferential direction and a numerical solution in the meridional direction via the differential quadrature method (DQM). After validation of the presented model, the influences of various variables on the natural frequencies and loss factors of the shell are investigated including circumferential wave number, magnetic field density, and geometrical parameters of the shell such as semi-vertex angle, length, total thickness and thickness of the MR core. [ABSTRACT FROM AUTHOR]

PURPOSE: Gene fusions are established oncogenic drivers and emerging therapeutic targets in advanced colorectal cancer. This study aimed to detail the frequencies and clinicopathological features of gene fusions in colorectal cancer using a circulating tumor DNA assay. METHODS: Circulating tumor DNA samples in patients with advanced colorectal cancer were analyzed at 4,581 unique time points using a validated plasma-based multigene assay that includes assessment of fusions in FGFR2 , FGFR3 , RET , ALK , NTRK1 , and ROS1. Associations between fusions and clinicopathological features were measured using Fisher's exact test. Relative frequencies of genomic alterations were compared between fusion-present and fusion-absent cases using an unpaired t test. RESULTS: Forty-four unique fusions were identified in 40 (1.1%) of the 3,808 patients with circulating tumor DNA detected: RET (n = 6; 36% of all fusions detected), FGFR3 (n = 2; 27%), ALK (n = 10, 23%), NTRK1 (n = 3; 7%), ROS1 (n = 2; 5%), and FGFR2 (n = 1; 2%). Relative to nonfusion variants detected, fusions were more likely to be subclonal (odds ratio, 8.2; 95% CI, 2.94 to 23.00; P <.001). Mutations associated with a previously reported anti–epidermal growth factor receptor (anti-EGFR) therapy resistance signature (subclonal RAS and EGFR mutations) were found with fusions in FGFR3 (10 of 12 patients), RET (nine of 16 patients), and ALK (seven of 10 patients). For the 27 patients with available clinical histories, 21 (78%) had EGFR monoclonal antibody treatment before fusion detection. CONCLUSION: Diverse and potentially actionable fusions can be detected using a circulating tumor DNA assay in patients with advanced colorectal cancer. Distribution of coexisting subclonal mutations in EGFR , KRAS , and NRAS in a subset of the patients with fusion-present colorectal cancer suggests that these fusions may arise as a novel mechanism of resistance to anti-EGFR therapies in patients with metastatic colorectal cancer. [ABSTRACT FROM AUTHOR]

PURPOSE: Gene fusions are established oncogenic drivers and emerging therapeutic targets in advanced colorectal cancer. This study aimed to detail the frequencies and clinicopathological features of gene fusions in colorectal cancer using a circulating tumor DNA assay. METHODS: Circulating tumor DNA samples in patients with advanced colorectal cancer were analyzed at 4,581 unique time points using a validated plasma-based multigene assay that includes assessment of fusions in FGFR2 , FGFR3 , RET , ALK , NTRK1 , and ROS1. Associations between fusions and clinicopathological features were measured using Fisher's exact test. Relative frequencies of genomic alterations were compared between fusion-present and fusion-absent cases using an unpaired t test. RESULTS: Forty-four unique fusions were identified in 40 (1.1%) of the 3,808 patients with circulating tumor DNA detected: RET (n = 6; 36% of all fusions detected), FGFR3 (n = 2; 27%), ALK (n = 10, 23%), NTRK1 (n = 3; 7%), ROS1 (n = 2; 5%), and FGFR2 (n = 1; 2%). Relative to nonfusion variants detected, fusions were more likely to be subclonal (odds ratio, 8.2; 95% CI, 2.94 to 23.00; P <.001). Mutations associated with a previously reported anti–epidermal growth factor receptor (anti-EGFR) therapy resistance signature (subclonal RAS and EGFR mutations) were found with fusions in FGFR3 (10 of 12 patients), RET (nine of 16 patients), and ALK (seven of 10 patients). For the 27 patients with available clinical histories, 21 (78%) had EGFR monoclonal antibody treatment before fusion detection. CONCLUSION: Diverse and potentially actionable fusions can be detected using a circulating tumor DNA assay in patients with advanced colorectal cancer. Distribution of coexisting subclonal mutations in EGFR , KRAS , and NRAS in a subset of the patients with fusion-present colorectal cancer suggests that these fusions may arise as a novel mechanism of resistance to anti-EGFR therapies in patients with metastatic colorectal cancer. [ABSTRACT FROM AUTHOR]

In this paper, the supersonic flutter characteristics of truncated sandwich conical shells with the magnetorheological (MR) core and isotropic homogeneous host and constraining layers are studied. The mathematical modeling of the shell and the aerodynamic pressure sequentially are performed utilizing the first-order shear deformation theory (FSDT) and the supersonic piston theory incorporating the effects of curvature and aerodynamic damping. The set of the governing equations and associated boundary conditions are derived using Hamilton's principle. Through an analytical solution in the circumferential direction and a numerical solution in the meridional direction via the differential quadrature method (DQM), a semi-analytical solution is provided for various boundary conditions. After validation of the presented model, the effects of various parameters on the aeroelastic stability regions of the shell are examined such as magnetic field density, semi-vertex angle, length, total thickness, and thickness of the MR core. [ABSTRACT FROM AUTHOR]