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Two novel experiments, one concerned with the fast optical response related to Cooper pair breaking using femto-second laser pulses in YBCO films and the second related to uncorrelated dynamic distortions as a function of oxygen concentration for YBCO single crystals by ion channeling, have provided information that may be relevant for understanding the mechanism of superconductivity in high Tc superconductors. In the first case a dramatic resonant photon energy dependence around 1.5 eV in the pair breaking rate has been observed, suggesting that an intermediate excitation may be playing an important role in the depairing process. In the second experiment, ion channeling investigations in YBa2Cu3O7-(delta ) ((delta) equals 0.05 to 0.8) crystals have clearly shown an evolution of the lattice from that of a Debye solid for (delta) equals 0.8 to one exhibiting significant lattice coherence even at much higher temperatures than Tc, with discontinuities which track Tc. These two experimental results are discussed in the light of different mechanisms including the formation of Zhang-Rice singlet or other mechanisms that lead to a non local hole.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Wire-bonding in IC assembly process involves making a physical connection between the IC 'die' and the 'lead' by bonding wires between the two. Inspection of wire-bond quality is a' highly labor-intensive process and currently efforts are being made to automate it. This paper presents the results of a research conducted into developing a comprehensive automated wire- bond visual inspection system that is capable of performing final accept/reject inspection, providing on-line process feedback, and assisting in process validation. The proposed inspection system consists of the inspection of the bond on a bond pad, the bond on a lead and the inter-connecting wire between a bond pad and its corresponding lead. The algorithms are based on simple and easily extractable features that ensure achieving the desired accuracy and speed. A novel but simple illumination system is proposed to obtain the images of the inter- connecting wires. The proposed system is validated using several state-of-the-art IC samples. This work is sponsored by the Ministry of Science Technology and Environment, Malaysia and Intel Technology Pvt. Ltd., Malaysia.

This study reviews the state-of-the-art multiobjective optimisation (MOO) techniques with metaheuristic through clustering approaches developed specifically for image segmentation problems. The authors treat image segmentation as a real-life problem with multiple objectives; thus, focusing on MOO methods that allow a trade-off among multiple objectives. A reasonable solution to a multiobjective (MO) problem is to investigate a set of solutions, each of which satisfies the objectives at an acceptable level without being dominated by any other solution. The primary difference of MOO methods from traditional image segmentation is that instead of a single solution, their output is a set of solutions called Pareto-optimal solution. This study discusses the evolutionary and non-evolutionary MO clustering techniques for image segmentation. It diagnoses the requirements and issues for modelling MOO via MO clustering technique. In addition, the potential challenges and the directions for future research are presented.

We have investigated the optical response of single grain-boundary weak-links in superconducting YBCO thin films. At the superconducting transition of a film containing a single grain-boundary weak-link we observed an enhanced optical response from the weak- link. Below the transition temperature, we measure the bias current and the temperature dependence of the optical response of the grain-boundary in the temperature range of 15 K < T < 80 K. Using a Resistively-Shunted-Junction model for the grain-boundary weak- link, we find that the optical response in this temperature range can be described by radiation induced thermal modulation of the critical currents.

Third Internal Visual Inspection in the IC assembly process deals with the wire bond quality inspection and is a very labor intensive stage. This paper describes a simple but comprehensive prototype model developed to automate the inspection of wedge and ball bonds. It is assumed that the die tilt is within specifications and the bond pad is automatically aligned. The defects associated with the bond quality are classified into four categories: size, shape, position and dimension. The bond is inspected sequentially for each category of defects and is rejected without further processing when any defect is detected. The procedure adopted in the prototype is as follows: A global thresholding technique automatically binarizes the intensity image of the bond. Bond limits are determined by a scanning procedure. Simple techniques such as pixel count, MER, Centroid and Median are used to verify the specifications related to size and shape. An intelligent scanning technique inspects the position related specifications in addition to identifying the wire and tail positions of the bond. The dimensions of the bond are determined by using projection information. 100% success is achieved with the experiments conducted using 100 sample images.© (1993) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

We have performed depth profile analyses of the lattice parameters in epitaxial thin films of La0.67Ca0.33MnO3 to understand the evolution of strain relaxation processes in these materials. The analyses were done using grazing incidence x-ray scattering on films of different thicknesses on (100)-oriented LaAlO3 with a lattice mismatch of −2%. We find that such films exhibit two and sometimes up to three in-plane strained lattice constants, corresponding to a slight orthorhombic distortion of the crystal, as well as near-surface lattice relaxation. As a function of film thickness, we find that the strain is in the same order of magnitude up to a thickness of 70–80nm, after which the strain begins to relax towards the bulk value of the lattice parameters. In addition, we find a depth behavior in the strain which is consistent with the formation of nonuniformly strained islands in the sample.

We report charge-ordered Bi0.4Ca0.6MnO3 thin films with charge-ordering temperature near room temperature, and observation of large photoinduced resistivity changes in these films associated with melting of the charge ordering by visible light. Films grown under small compressive strain exhibit the largest photoinduced resistivity changes. The lifetime of the photoinduced low-resistance state is on the order of half a minute. These photoinduced resistivity changes in thin films of Bi0.4Ca0.6MnO3 make them very promising for photonic device application.

We report our studies of the angular magnetic field dependence of the critical current density in epitaxial thin films of Nd 1.85 Ce 0.15 CuO 4−δ in the temperature range 1.4 K to 14 K. At low temperatures, the critical current anisotropy is well described by the 2D model of Josephson- coupled vortices. At temperatures above 10K, we observe deviations from the 2D behavior which may be attributed to the temperature dependence of the coherence length. The field dependence of the critical current density for the field orientation parallel to the CuO 2 planes is consistent with the dimensionality indicated by the angular dependence at all temperatures.

Web services are the internet enabled applications for performing business needs, considered as the platform-independent and loosely coupled. Web service compositions build new services by organizing a set of existing services by providing reusability and interoperability. The research problem in web service composition is to obtain best effective services with the composition of services based on maximum quality of services (QoS) and satisfy the user’s requirements. This study reveals various challenges in the QoS parameter for Web service composition because it is difficult to recognize. We have illustrated the related technology by analyzing QoS parameters based on existing algorithms with composition patterns and compared the results.

The shortest/optimal path generation is essential for the efficient operation of a mobile robot. Recent advances in robotics and machine intelligence have led to the application of modern optimization method such as the genetic algorithm (GA), to solve the path-planning problem. However, the genetic algorithm path planning approach in the previous works requires a preprocessing step that captures the connectivity of the free-space in a concise representation. In this paper, GA path-planning approach is enhanced with feasible path detection mechanism based on traversability vectors method. This novel idea eliminates the need of free-space connectivity representation. The feasible path detection is performed concurrently while the GA performs the search for the shortest path. The performance of the proposed GA approach is tested on three different environments consisting of polygonal obstacles with increasing complexity. In all experiments, the GA has successfully detected the near-optimal feasible...

A careful analysis of high-resolution transmission electron microscopy images from La0.8Ca0.2MnO3 thin films indicates that the images can not explained based on either the classical Pnma structure or its monoclinic distortion. A cation ordered structure is proposed which could be responsible for the significantly higher Tc of the film (298K) compared with the bulk material of the same composition (190K).