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We present a Newton‐type method for reconstructing planar sound‐soft or perfectly conducting cracks from far‐field measurements for one time‐harmonic scattering with plane wave incidence. Our approach arises from a method suggested by Kress and Rundell (Inv. Probl.2005; 21(4):1207–1223) for an inverse boundary value problem for the Laplace equation. It was extended to inverse scattering problems for sound‐soft obstacles (Mathematical Methods in Scattering Theory and Biomedical Engineering. World Scientific: Singapore, 2006; 39–50) and for sound‐hard cracks (Inv. Probl.2006; 22(6)). In both cases it was shown that the method gives accurate reconstructions with reasonable stability against noisy data. The approach is based on a pair of nonlinear and ill‐posed integral equations for the unknown boundary. The integral equations are solved by linearization, i.e. by regularized Newton iterations. Numerical reconstructions illustrate the feasibility of the method. Copyright © 2007 John Wiley & Sons, Ltd.

It is highly recommended that future mechatronic systems will increasingly require self diagnosis and fault detection capabilities when designed as stand alone system the smart aircraft actuator. In this paper we deal with some signal based sensor fault detection schemes as well as model based FDI-schemes like the EKF used for system critical parameter estimation for actuator diagnose purpose. Concluding, a µ-robust realization for online-FDI will be mentioned as a regard for future development.

In modern smart actuator concepts the actuator control electronic includes built-in test procedures for fault detection and isolation (FDI). To improve the test depth this paper presents analytic methods which allow a precise and comprehensive fault detection. The application discusses parity space methods for a modern direct drive valve (DDV) which comprises strong non-linearities. The feasibility and onboard application are also exposed.

ABSTRACTIn the early developmental stages of robotics, hydraulics played an important role. Many of the early high-payload capacity manipulators were actuated by hydraulic cylinders and hydraulic rotary actuators. As the power-to-weight ratio of electric motors increased, they eventually came to be the preferred form of actuation for robotic manipulators because of the relative ease of operation, control, and maintenance for general cleanliness. Recently, however, task requirements have dictated that manipulator payload capacity increase to accommodate greater payloads, greater manipulator length, and larger environmental interaction forces. In order to successfully design, build, and deploy a new hydraulic manipulator (or subsystem), sophisticated modeling, analysis, and control experiments are usually needed. Oak Ridge National Laboratory (ORNL) has a history of projects that incorporate hydraulics technology, including mobile robots, teleoperated manipulators, and full-scale construction equipment. The purpose of this article is to describe the hydraulic manipulator research capabilities at ORNL. Included are experimental results from ORNL's teleoperated human-amplifier and a custom-designed hydraulic manipulator.

We give a simple method based on Cauchy's integral formula for estimating the errors of numerical approximation for periodic analytic functions. We then obtain error estimates for the quadrature formulas of Chawla and Ramakrishnan [1] for the numerical evaluation of the Cauchy principal value integral

A Neumann boundary value problem for the equation rot ?-??=0 is considered in 29-1 and 29-2. The approach is by transforming the boundary value problem into an equivalent boundary integral equation deduced from a representation formula for solutions of rot ?-??=0 based on the fundamental solution of the Helmholtz equation. In particular, for the two-dimensional case a detailed discussion of the integral equation is carried out including the approximate solution by numerical integration.

Summary Brakhage and Werner, Leis and Panich suggested to reduce the exterior Dirichlet boundary value problem for the Helmholtz equation to an integral equation of the second kind which is uniquely solvable for all frequencies by seeking the solution in the form of a combined double- and single-layer potential. We present an analysis of the appropriate choice of the parameter coupling the double- and single-layer potential in order to minimize the condition number of the integral operator.

Summary In a general Hilbert space of periodic functions numerical approximations with equidistant nodes for any bounded linear functional are given which are of minimal error norm in the class of approximations being exact for certain trigonometric polynomials. In examples optimal quadrature formulas with such side conditions are considered.

Summary Optimal rules of numerical approximation of bounded linear functionals in a general Hilbert space of periodic functions are investigated by Davis' method. The weights and error norms for optimal rules with equidistant nodes for an arbitrary bounded linear functional are given explicitly in terms of a total orthonormal system in the Hilbert space. Further the optimal approximation rules are compared with the numerical approximations obtained by means of trigonometric interpolation. As examples the numerical integration and the numerical evaluation of conjugate harmonic functions are considered in two distinct Hardy spaces and also in Sobolev spaces.

The purpose of this paper is to develop a controller for a force-reflecting teleoperator system having kinematically dissimilar master and slave. The controller is a stiffness controller for both the master and the slave. A mathematical problem associated with representing orientations using Euler angles is described, and Euler parameters are proposed as a solution. The basic properties of Euler parameters are presented, specifically those pertaining to stiffness control. The stiffness controller for both the master and the slave is formulated using Euler parameters to represent orientation and a Liapunov stability proof is presented for the controller. The master portion of the control scheme is implemented on a six-degree-of-freedom master.

The object of this study was to devise a unified method for comparing different thermal techniques for the estimation of blood perfusion rates and to perform a comparison for several common techniques. The approach used was to develop analytical models for the temperature response for all combinations of five power deposition geometries (spherical, one- and two-dimensional cylindrical, and one- and two-dimensional Gaussian) and three transient heating techniques (temperature pulse-decay, temperature step function, and constant-power heat-up) plus one steady-state heating technique. The transient models were used to determine the range of times (the time window) when a significant portion of the transient temperature response was due to blood perfusion. This time window was defined to begin when the difference between the conduction-only and the conduction-plus-blood flow transient temperature (or power) responses exceeded a specified value, and to end when the conduction-plus-blood flow transient temperature (or power) reached a specified fraction of its steady-state value. The results are summarized in dimensionless plots showing the size of the time windows for each of the transient perfusion estimation techniques. Several conclusions were drawn, in particular: (a) low perfusions are difficult to estimate because of the dominance of conduction, (b) large heated regions are better suited for estimation of low perfusions, (c) noninvasive heating techniques are superior because they have the potential to minimize conduction effects, and (d) none of the transient techniques appears to be clearly superior to the others.

Summary For the equation rotv-?v=0 with ? not necessarily constant a boundary value problem of Neumann's type is solved by reducing it to an equivalent integral equation.

Für die numerische Quadratur uneigentlicher Integrale über die reelle Achse bei analytischen Funktionen werden Quadratur-formeln mit unendlich vielen äquidistanten Stützstellen betrachtet. In einem Hardyschen Raum wird die L1-Norm des Fehlers bei der Rechteckregel bestimmt, und es wird ferner eine Quadraturformel mit minimaler Fehlernorm angegeben.

The purpose of this paper is to develop a controller for a force-reflecting teleoperator system having kinematically dissimilar master and slave. The controller is a stiffness controller for both the master and the slave. A mathematical problem associated with representing orientations using Euler angles is described, and Euler parameters are proposed as a solution. The basic properties of Euler parameters are presented, specifically those pertaining to stiffness control. The stiffness controller for both the master and the slave is formulated using Euler parameters to represent orientation and a Liapunov stability proof is presented for the controller. The master portion of the control scheme is implemented on a six-degree-of-freedom master.

AMS(MOS): 65L10The convergence of the discrete Green's function gh is studied for finite difference schemes approximating m-th order linear two-point boundary value problems. Schemes of noncompact form and in part of the paper also nonuniform grids are admitted. Sharp convergence results are obtained for the difference quotients of gh up to order m-1.

We describe the numerical construction of constant-alpha force-free fields with vanishing normal components on the boundary of a torus by a boundary integral equation approach.

A sequence of interpolation series is given which generalizes Whittaker's cardinal function to the case of Hermite interpolation. By integrating the interpolation series, a sequence of new quadrature formulae for is obtained. Derivative-free remainders are stated for these interpolation and quadrature formulae.

Unter Verwendung der Davisschen Methode werden neue ableitungsfreie Darstellungen und Schranken gefunden für den Fehler bei der numerischen Berechnung konjugierter Funktionen nach dem Wittichschen Verfahren.

A scalable processor architecture for multi-threaded Java™ applications is presented. The proposed architecture consists of multiple application-specific processing elements, each able to execute a single thread at one time. The architecture is evaluated by implementing a portable and scalable Java machine on an FPGA board for demonstration.

A scalable parallel ASIP architecture based on FPGAs suitable for the implementation of reactive systems is described. The specification language used is extended statecharts. An industrial example requiring the real-time control of several stepper motors illustrates the benefits of the approach.

The question of non-uniqueness in boundary integral equation formulations of exterior boundary-value problems in time-harmonic acoustic and electromagnetic scattering can be resolved by seeking the solutions in the form of a combined single and double-layer potential in acousties or a combined electric- and magnetic-dipole field in electromagnetics. We present an analysis of the appropriate choice of the coupling parameters which is optimal in the sense of minimizing the condition number of the boundary integral operators.

To overcome the non-uniqueness problem arising in integral equations for the exterior boundary-value problems for the Helmholtz equation, Jones recently suggested adding a series of outgoing waves to the free-space fundamental solution. We present an analysis on the appropriate choice of the coefficients occurring in this series in order to minimize the condition number of the integral equations.