Deposits of clastic carbonate-dominated (calciclastic) sedimentary slope systems in the rock record have been identified mostly as linearly-consistent carbonate apron deposits, even though most ancient clastic carbonate slope deposits fit the submarine fan systems better. Calciclastic submarine fans are consequently rarely described and are poorly understood. Subsequently, very little is known especially in mud-dominated calciclastic submarine fan systems. Presented in this study are a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) that reveals a >250 m thick calciturbidite complex deposited in a calciclastic submarine fan setting. Seven facies are recognised from core and thin section characterisation and are grouped into three carbonate turbidite sequences. They include: 1) Calciturbidites, comprising mostly of highto low-density, wavy-laminated bioclast-rich facies; 2) low-density densite mudstones which are characterised by planar laminated and unlaminated muddominated facies; and 3) Calcidebrites which are muddy or hyper-concentrated debrisflow deposits occurring as poorly-sorted, chaotic, mud-supported floatstones. These

Phd by thesis

http://foresight.ifmo.ru/ict/shared/files/201311/1_123.pdf

Decentralized control: An overview

We investigate the behavior of quasi-Newton algorithms applied to minimize a nonsmooth function f , not necessarily convex. We introduce an inex- act line search that generates a sequence of nested intervals containing a set of points of nonzero measure that satisfy the Armijo and Wolfe conditions if f is absolutely continuous along the line. Furthermore, the line search is guaranteed to terminate if f is semi-algebraic. It seems quite difficult to establish a convergence theorem for quasi-Newton methods applied to such general classes of functions, so we give a care- ful analysis of a special but illuminating case, the Euclidean norm, in one variable using the inexact line search and in two variables assuming that the line search is exact. In practice, we find that when f is locally Lipschitz and semi-algebraic with bounded sublevel sets, the BFGS (Broyden-Fletcher-Goldfarb-Shanno) method with the inexact line search almost always generates sequences whose cluster points are Clarke stationary and with function values converging R-linearly to a Clarke station- ary value. We give references documenting the successful use of BFGS in a variety of nonsmooth applications, particularly the design of low-order controllers for linear dynamical systems. We conclude with a challenging open question.

/pdf/nonsmooth-optimization-via-quasi-newton-methods-14v2jl5o1y.pdf

Nonsmooth optimization via quasi-Newton methods

The objective is to control a web transport system with winder and unwinder for elastic material. A physical modeling of this plant is made based on the general laws of physics. For this type of control problem, it is extremely important to prevent the occurrence of web break or fold by decoupling the web tension and the web velocity. Due to the wide-range variation of the radius and inertia of the rollers the system dynamics change considerably during the winding/unwinding process. Different strategies for web tension control and linear transport velocity control are presented. First, an H/sub /spl infin// robust control strategy which reduces the coupling between tension and velocity, is compared to the decentralized control strategy with proportional integral derivative (PID) controllers commonly used in the industry. Second, an H/sub /spl infin// robust control strategy with varying gains is shown to render the control more robust to the radius variations. Then, a linear parameter varying (LPV) control strategy with smooth scheduling of controllers is synthesized for different operating points and compared to the previous methods. Finally, this LPV control and the H/sub /spl infin// robust control strategy with varying gains are combined to give the best results on an experimental setup, for the rejection of the disturbances introduced by velocity variations and for the robustness to radius and inertia changes.

Modeling and robust control of winding systems for elastic webs

Ieee transactions on control systems technology

In web transport systems, the main concern is to control independently speed and tension in spite of perturbations such as radius variations and changes of setting point. Multivariable controllers including gain scheduling have already given good results in that sense. Nevertheless, in these control techniques, tracking properties and perturbation rejection are interdependent and cannot be specified separately. In this paper, we present multivariable H/sub /spl infin// robust control with two degrees of freedom (2DOF) and gain scheduling applied to winding systems. Three controller structures are considered: a global controller, a semidecentralized controller, and a semidecentralized controller with overlapping. Simulation results are given, based on a nonlinear model identified on an experimental bench. In each case, the 2DOF controller is compared to the classical 1DOF controller. The 2DOF approach allows improving significantly disturbance rejection while reducing coupling between tension and velocity.

Tension control for winding systems with two-degrees-of-freedom H/sub /spl infin// controllers

Robust decentralised control strategies for large-scale web handling systems

Tension control for winding systems with two degrees of freedom H/sub ∞/ controller

Flexible materials such as textiles, papers, polymers, and metals are transported on rollers during their processing. Maintaining web tension in the entire processing line under changing web speed is a key factor in achieving good final product quality. Many industrial applications use dancer position feedback to indirectly regulate tension. Although widely used in the industry, pendulum dancers (rotational motion of the dancer roller) have received very little attention in the literature compared to linear ones (translational motion). The lack of clearly identified controllers synthesis methods can thus be noticed, as industry typically uses hand-tuned decentralized PI controllers. An improved alternative based on H∞ methods is proposed in this paper to provide a systematic framework. The focus in this study is the unwind section of a processing line that contains a pendulum dancer (PD). The nonlinear and linear phenomenological models of the unwind section containing the PD are discussed first. The position controller based on dancer position feedback is synthesized using the standard H∞ approach with mixed sensitivity. Because of the high order of the controllers synthesized with this approach, techniques to generate reduced-order controllers are used to calculate a fixed-order controller resembling standard industrial practice. The performance of the proposed controllers is demonstrated by carrying out experiments on a large experimental web handling platform containing four driven rollers, many idle rollers, and a PD in the unwind section. To the best of our knowledge, these are the first published results of successful application of an H∞ controller to a real plant containing a PD.

Dominique Knittel

Papers

Tension control for winding systems with two-degrees-of-freedom H/sub /spl infin// controllers

Robust decentralised control strategies for large-scale web handling systems

Tension control for winding systems with two degrees of freedom H/sub ∞/ controller

Fixed-Order $H_{\infty}$ Tension Control in the Unwinding Section of a Web Handling System Using a Pendulum Dancer

Modeling and experimental results of an Archimedes screw turbine