A5082783271- Metal and Thin Film Mechanics
- Aluminum Alloys Composites Properties
- Advanced materials and composites
- Control Systems and Identification
- Advanced Control Systems Optimization
- Iterative Learning Control Systems
- Magnesium Alloys: Properties and Applications
- Fusion materials and technologies
- Microstructure and mechanical properties
- Nuclear Materials and Properties
- Structural Health Monitoring Techniques
- Dynamics and Control of Mechanical Systems
- Microstructure and Mechanical Properties of Steels
- Advanced ceramic materials synthesis
- Adaptive optics and wavefront sensing
- Advanced Adaptive Filtering Techniques
- Ion-surface interactions and analysis
- Boron and Carbon Nanomaterials Research
- Stability and Control of Uncertain Systems
- Diamond and Carbon-based Materials Research
- Probabilistic and Robust Engineering Design
- Intermetallics and Advanced Alloy Properties
- Fault Detection and Control Systems
- Advanced Surface Polishing Techniques
- Stability and Controllability of Differential Equations
RWTH Aachen University
2017-2023
University of Oxford
2012-2023
University of California, Los Angeles
2000-2011
Gemini North Observatory
2000
California State University Los Angeles
1988-1990
Iowa State University
1980
Garden Organic
1953
The minimum-time manipulator control problem is solved for the case when path specified and actuator torque limitations are known. optimal open-loop torques found, a method given implementing these with conventional linear feedback system. algorithm allows bounds on that may be arbitrary functions of joint angles angular velocities. This valid any orientation end- effector specified. can used has rigid links, known dynamic equations motion, determined at position path.
High speed motions and increased productivity are linked in the industrial applications of many robotic manipulators, yet speeds which can be achieved by a manipulator during given task limited number factors. The dynamic properties its actuator limitations characteristics probably most important This paper presents an optimal control policy results minimum-time motion for along any predetermined path three dimensional space. technique permits user to specify completely arm; therefore method...
This paper presents an investigation of the design and implementation minimum-variance adaptive controllers for computer hard disk drive (HDD) read-write track following. A common characteristic controllers, or not, is that they rely on prediction filters with large high-frequency gains to predict broadband disturbances, this often produces control-signal saturation eventual loss stability. Two methods are introduced here address issue. The first method, suitable online control, uses...
Two grades of pure tungsten, single and polycrystalline, were irradiated for 282 days in the HFR reactor, Petten, at 900 °C to an average damage level 1.6 dpa. Each grade tungsten was investigated using transmission electron microscope (TEM) assess effect neutron irradiation on microstructure. Investigations revealed formation faceted cavities, whose diameter varies from 4 14 nm both materials. The cavities are homogeneously distributed only inside crystalline tungsten. local distribution...
The physical properties of tungsten such as the high melting point 3420°C, strength and thermal conductivity, low expansion erosion rate make this material attractive a plasma facing material. However, manufacturing parts by mechanical machining milling turning is extremely costly time intensive because very hard brittle. Powder Injection Molding (PIM) special process allows mass production components, joining different materials without brazing creation composite prototype materials, an...
Nanoindentation has been performed on tungsten, unimplanted and helium-implanted to ~600 appm, at temperatures up 750 °C. The hardening effect of the damage was 0.90 GPa 50 °C, but is negligible above 450 hardness value a given temperature did not change re-testing after heating This suggests that helium trapped in small vacancy complexes are stable least which can be bypassed due increased dislocation mobility (cross slip or climb)
Only limited data exist on the effect of neutron irradiation brittle to ductile transition (BDT) in tungsten. This work investigates increase temperature (BDTT) following 1.67 displacements per atom, using four-point bend tests over a range temperatures (623–1173 K) and strain rates (3.5 × 10−7 - 2.5 10−5 s−1). The BDTT was found by 500 K after irradiation. activation energy for BDT determined Arrhenius analysis tests. Nanoindentation strain-rate jump were used characterise volume...
A promising approach to deform metallic-intermetallic composite materials is the application of electric current pulses during deformation process achieve a lower yield strength and enhanced elongation fracture. This known as electroplastic effect. In this work, novel setup study effect nanoindentation on individual phases well-defined interfaces was developed. Using eutectic Al-Al2Cu alloy model material, results were directly compared with macroscopic compression tests. The micro-...
<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> This paper introduces a frequency-weighting method for adaptive disturbance rejection. The constrains the high-frequency gain of prediction filter in minimum-variance controller. In an experimental application, is used to control microelectromechanical system fast steering mirror suppress laser beam jitter. analyzes effect sensor noise on performance and demonstrates that sufficient levels and/or...
We show here, based on VAlN, TiAlN and the related oxynitrides, that (brittle) fracture elastic properties may be consistently modelled from quantum- to continuum mechanics using micromechanical testing link both scales. The measured moduli match closely with those predicted by density functional theory calculations. Good agreement was also observed between micro-cantilever bending experiments cohesive-zone-finite element modelling. These scale-bridging data serve as a baseline for future...
Micro-mechanical testing techniques have proved successful in extracting the properties of bulk materials from small-scale tests. In particular, focussed ion beam (FIB)-machined micro-cantilevers been shown to produce quantitative, accurate modulus values when used on such as pure copper or silicon. this work, technique is extended study micro-mechanical ion-irradiated, commercially tungsten. Ion irradiation has model cascade damage produced by fusion neutrons Due small depth ion-implanted...