Laser-induced spatially-selective tailoring of high-index dielectric metasurfaces

Optically resonant high-index dielectric metasurfaces featuring Mie-type electric and magnetic resonances are usually fabricated by means of planar technologies, which limit the degrees of freedom in tunability and scalability of the fabricated systems. Therefore, we propose a complimentary post-processing technique based on ultrashort (≤ 10 ps)...

Constructing Two-Level Designs by Concatenation of Strength-3 Orthogonal Arrays

Two-level orthogonal arrays of N runs, k factors, and a strength of 3 provide suitable fractional factorial designs in situations where many of the main effects are expected to be active, as well as some two-factor interactions. If they consist of N/2 mirror image pairs, these designs are fold-over designs. They are called even and provide at...

Integrated Dual-Channel X-Band Offset-Transmitter for Phase Steering and DDMA Arrays

Multiple-Input and Multiple-Output (MIMO) arrays provide more degrees of freedom than conventional phased arrays. They require that every transmitting element of the array can be identified when received. One way to achieve this is to give every element its own unique frequency. Offset-transmitters may be used to introduce MIMO or Doppler...

Space-Time Block Coding waveform for suppression of jamming in a MIMO radar

In a phased array radar which uses Multiple Input Multiple Output (MIMO) techniques, each (group of) element(s) transmits a different waveform. This extra degree of freedom in the design of a phased array radar potentially yields an advantage for improved suppression of sidelobe clutter and jamming. In this paper a Space-Time Block Coding (STBC)...

Effective thermal/mechanical properties of honeycomb core panels for hot structure applications

The present work addresses the computation of the effective thermal and mechanical properties of a honeycombcore sandwich panel. The panel considered has a hexagon-cell honeycomb core. An alternative method, based on the Gebhart factors within a hexagonal cell, is presented in addition to the familiar Swann-Pittman method. The advantage of the...

A quantitative risk assessment tool for the external safety of industrial plants with a dust explosion hazard

A quantitative risk assessment (QRA) tool has been developed by TNO for the external safety of industrial plants with a dust explosion hazard. As a first step an industrial plant is divided into groups of modules, defined by their size, shape, and constructional properties. Then the relevant explosion scenarios are determined, together with...

Distributed control in adaptive optics: deformable mirror and turbulence modeling

Future large optical telescopes require adaptive optics (AO) systems whose deformable mirrors (DM) have ever more degrees of freedom. This paper describes advances that are made in a project aimed to design a new AO system that is extendible to meet tomorrow's specifications. Advances on the mechanical design are reported in a companion paper ...

Evaluation of new user interface features for the MANUS robot arm

New user interface features and a new user interface for the MANUS robot arm, were designed in order to reduce the high cognitive and physical load that users experience when controlling the MANUS. These interface features, and the new interface, were evaluated for their performance. The following results were obtained. A new method of switching...

Dynamic response analysis of concrete structures: Simplified design method and its limitations

The behaviour of dynamically loaded structures, like concrete containment structures and blast resistant control buildings, can be analysed with advanced numerical techniques as well as with less laborious engineering methods. Most used simplified method is the Single Degree of Freedom (SDOF) method, or the so-called Biggs method [1]. This paper...

Orifice impedance under grazing flow measured with a single microphone method

The effect of one-sided grazing mean flow on the acoustical impedance of rectangular orifices is measured at low Mach number and low Helmholtz number by means of a single microphone method. The results are fairly consistent with previous experimental results obtained by means of a two-microphone impedance tube. Furthermore no significant...

Statically determined structures: Tension between classical and modern design

The two most important characteristics of opto-mechanical structures used in space or for astronomy are high accuracy and stability. Much time, money and energy is invested in achieving this. However, because resources are limited, it is important to realize that the cost of an instrument is mainly determined during the design process. Three...

Dealing with friction in a reusable 6 degrees of freedom adjustment mechanism with sliding contacts

Although the possibility of a 6 degrees of freedom adjustment based on a single body pulled onto on six adjustable supports follows directly from the kinematic theory, such mechanisms are seldom used in actual products. Two major drawbacks for the use of this solution are: Due to the sliding contact between the body and the supports, friction...

An adjustment for five degrees of freedom as an alternative for a hexapod mechanism

Modem mirror optics often consists of a limited number of elements, in which many aberrations may be attacked by adjusting only one element in five degrees of freedom, i.e. all degrees of freedom except the rotation around the optical axis. When the adjustment has to be reusable and mass and stiffness are of importance, a hexapod mechanism is ...

Control performance with three translational degrees of freedom

For multiple DOF systems, it is important to detemine how accurately operators can control each DOF, and what the influence of the perceptual, information processing and psychomotor components on performance is. Sixteen right-handed male students participated in 2 experiments: one involving positioning and one involving tracking with 3...

Long term structural dynamics of mechanical systems with local nonlinearities

This paper deals with the long term behavior of periodically excited mechanical systems consisting of linear components and local nonlinearities. The number of degrees of freedom of the linear components is reduced by applying a component mode synthesis technique. Lyapunov exponents are used to identify the character of the long term behavior of...

Periodic solutions of a multi-DOF beam system with impact

The steady state behaviour is analyzed of a periodically driven multi-DOF beam system which has an elastic stop at its middle. The elastic stop is modelled in a continuous way by using the contact law of Hertz. The beam is modelled by using finite elements and subsequently reduced by using a component mode synthesis method. The steady state...