Enhanced image-based coordinate measurement using a super-resolution method

This paper proposed super-resolution measurement to improve the conventional image-based coordinate measurement system. An undesirable attribute showed by the conventional system is that increasing the accuracy of the system would compromise the field of view of the system. To improve this problem, image super-resolution techniques are proposed to preprocess the observed frames. A Lagrange–Newton method is derived specifically for automatic measurement consideration. Different a priori knowledge was also examined and it was identified that identity model is the most efficient a priori knowledge among the four a priori knowledge tested. Using the Lagrange–Newton method and identity model, an experiment is carried out to evaluate the proposed super-resolution measurement. The result showed that super-resolution measurement increases the accuracy of the system without compromising the field of view. Furthermore, it is also shown that super-resolution measurement can perform measurement on dimension not achievable using the conventional method.     

Maintaining a common co-ordinate system for a group of robots based on vision

This work presents a novel approach to the problem of establishing and maintaining a common co-ordinate system for a group of robots. A camera system mounted on top of a robot and vision algorithms are used to calculate the relative position of each surrounding robot. The watched movement of each robot is compared to the reported movement which is sent over some communication link. From this comparison a co-ordinate transformation is calculated. The algorithm was tested in simulation and is at the moment being implemented on a real robot system. Preliminary results of real world experiments are being presented.     

Advanced NDT methods for evaluating concrete bridges and other structures

Several advances in methods and equipment for sonic and ultrasonic non destructive testing (NDT) of concrete structures are presented, including advances for methods applicable to large structures such as bridges and dams. These new advances and methods greatly increase the speed and accuracy of many NDT investigations, and allow collection of NDT information previously not readily obtainable. The first topic presented is a brief overview of the impact echo (IE) method along with a case history on how is has been employed in testing concrete structures. The IE method is used to locate damage and determine member thickness when access is available from one side only. The next topic is a relatively new N DT method for concrete using surface waves analysis, in a method known as the spectral analysis of surface waves (SASW) technique. This allows the determination of the shear wave velocity profile versus depth for any layered system and is particularly applicable to testing pavements, slabs, tunnels, shaft liners, and massive concrete structures. For bridges and dams, the technique is particularly effective in determining the depth of weathering effects on the concrete. Included is an overview of the method and the principles behind it, as well as some case history examples. The final topic presented is an advance in the technique of ultrasonic plus velocity (UPV) testing. This advance involves the use of rapid scanning techniques to greatly increase the speed and utility of UPV testing. The U PV method uses compression wave energy which is sent through a member and the arrival time, wave amplitude, and velocity are recorded and computed. This new scanning technology allows the near-continuous acquisition of data along any given path over a structure. Included is test data collected using the scanning system to show the great increase in testing speed and utility of scanner-collected data when compared to traditional point-by-point methods.     

The boundary element method applied to a moving free boundary problem

In this paper a boundary problem is considered for which the boundary is to be determined as part of the solution. A time‐dependent problem involving linear diffusion in two spatial dimensions which results in a moving free boundary is posed. The fundamental solution is introduced and Green’s Theorem is used to yield a non‐linear system of integral equations for the unknown solution and the location of the boundary. The boundary element method is used to obtain a numerical solution to this system of integral equations which in turn is used to obtain the solution of the original problem. Graphical results for a two‐dimensional problem are presented. Published in 1999 by John Wiley & Sons, Ltd.     

Automatically exploiting implicit parallelism in Java

In this paper we show how implicit parallelism in Java programs can be made explicit by a restructuring compiler using the multi-threading mechanism of the language. In particular, we focus on automatically exploiting implicit parallelism in loops and multi-way recursive methods. Expressing parallelism in Java itself clearly has the advantage that the transformed program remains portable. After compilation of the transformed Java program into byte-code, speedup can be obtained on any platform on which the Java byte-code interpreter supports the true parallel execution of threads. Moreover, we will see that the transformations presented in this paper only induce a slight overhead on uni-processors. © 1997 John Wiley & Sons, Ltd.     

Fixed-structure robust controller synthesis via decentralized static output feedback

This paper describes and illustrates a unified methodology for robust, fixed-structure controller synthesis. The approach is based upon direct fixed-structure controller synthesis using a decentralized static output feedback formulation as a general framework for representing a large class of controller structures. Scaled Popov bounds for the real structured singular value are used to account for real parameter uncertainty and provide the means for optimizing a worst-case ℋ︁₂ cost bound with respect to the free parameters of the controller. Quasi-Newton optimization algorithms are used to solve the resulting numerical optimization problem. Initial stability multiplier and scaling matrices needed in scaled Popov synthesis are obtained by solving an LMI feasibility problem. Using both centralized and decentralized controller structures, numerical results are obtained for a 16th-order acoustic duct model with uncertain damped natural frequencies and for a two-dimensional beam-spring model with uncertain actuator locations. © 1998 John Wiley & Sons, Ltd.     

Effect of silane coupling agent on the chemorheological behaviour of epoxidised natural rubber filled with precipitated silica

Results of measurements of physical properties and solvent swelling of the extrudates indicate that epoxidised natural rubber (ENR) interacts chemically with precipitated silica when the mix of the two was extruded at 150–170°C in a Monsanto Processability Tester (MPT). The extent of interaction between the rubber and the filler depends on the extrusion time, the volume fraction of the filler, the shear rate and the addition of the silane coupling agent, namely N-3-(N-vinyl benzyl amino) ethyl-γ-amino propyl trimethoxy silane monohydrochloride. The activation energy of the chemical interaction between ENR and silica decreases on the addition of the silane coupling agent.     

Task-Related Differences in the Cuticular Hydrocarbon Composition of Harvester Ants, Pogonomyrmex barbatus

Colonies of the harvester ant, Pogonomyrmex barbatus, perform a variety of tasks. The behavior of an individual worker appears to depend on its recent history of brief contacts with ants of the same and other task groups. The purpose of this study was to determine whether task groups differ in cuticular hydrocarbon composition. We compared the cuticular hydrocarbon composition of ants collected under natural conditions as they performed one of three tasks: patrolling (locating food sources), foraging, or nest maintenance. Task groups differed significantly in the relative proportions of classes of hydrocarbon compounds, as well as in individual compounds. Relative to nest maintenance workers, foragers and patrollers had a higher proportion of straight-chain alkanes relative to monomethylalkanes, dimethylalkanes, and alkenes. There was no significant difference in the chain length of n-alkanes among the task groups. Foragers did not differ in hydrocarbon composition from patrollers. Colonies differed significantly from one another in hydrocarbon composition, but task groups differed in consistent ways from colony to colony, suggesting that the mechanism responsible for task-related hydrocarbon composition was the same in all colonies. P. barbatus workers switch tasks during their lifetimes, suggesting that cuticular hydrocarbon composition changes during adulthood as well. Nest maintenance workers are probably younger than foragers and patrollers and perform very little of their work outside of the nest. Task-related hydrocarbon differences detected here may be associated with worker age, and/or the abiotic characteristics (temperature, humidity, and ultraviolet light) of the interior and exterior work environments.     

Producing titanium powder by continuous vapor-phase reduction

One of the goals of the U.S. Department of Energy’s Albany Research Center is to reduce the cost of titanium parts by developing a continuous titanium process. In this work, titanium powder was produced by feeding liquid TiCl₄, with argon as a carrier gas, and magnesium wire into a shaft reactor at 1,000°C. The magnesium and TiCl₄ vaporized and reacted to produce a mixture of titanium, MgCl₂, and magnesium powder. Ti/Mg/MgCl₂ powder was removed from the argon gas stream by an electrostatic precipitator, and the titanium powder was separated from the magnesium and MgCl₂ by either vacuum distillation or leaching. Vacuum distillation produced sintered titanium powder with lower oxygen levels, but unacceptably high levels of magnesium and chlorine. Leached powder was spherical and free-flowing with low levels of magnesium and chlorine, but the oxygen content was no lower than 0.82%. The high oxygen content of the leached powder is caused by surface oxidation of the submicrometer titanium powder. For more information, contact S.J. Gerdemann, Albany Research Center-Department of Energy, 1450 Queen Avenue S.W., Albany, Oregon 97321-2198; (541) 967-5964; fax (541) 967-5868; e-mail gerdeman@alrc.doe.gov.