Identity conditions for nearest-neighbor and potential-function classifiers

The nearest-neighbor rule and the potential-function classifier are nonparametric discrimination methods that require the storage of a set of sample patterns. Here, a relationship between the two methods in terms of subclasses and superclasses is developed. Considering an exponential potential function, necessary and sufficient conditions for identity of their decision surfaces are obtained. Based on these conditions, an algorithm for establishing identity is introduced.     

On measuring the distance between histograms

A distance measure between two histograms has applications in feature selection, image indexing and retrieval, pattern classification and clustering, etc. We propose a distance between sets of measurement values as a measure of dissimilarity of two histograms. The proposed measure has the advantage over the traditional distance measures regarding the overlap between two distributions; it takes the similarity of the non-overlapping parts into account as well as that of overlapping parts. We consider three versions of the univariate histogram, corresponding to whether the type of measurement is nominal, ordinal, and modulo and their computational time complexities are Θ(b), Θ(b) and O(b²) for each type of measurements, respectively, where b is the number of levels in histograms.     

Macro-capp: A prototype capp system for an FMS

This paper deals with the role, advantages, problems and solution techniques for the implementation of dynamic Computer Aided Process Planning (CAPP) systems in a Felxible Manufacturing system (FMS). A large variety of part features for both rotational and prismatic parts are considered. A custom group technology coding technique is designed and implemented to describe part profile to system software concisely and comprehensively. The part profile code is assimilated by the system interactively. A prototype CAPP system was designed for a pseudo FMS containing multiple machining centres. The system described develops process plans that consider both alternative routes and methods to manufacture a part. Heuristic knowledge was implemented to choose between alternatives with flowtime minimization as the objective function. The system was tested and its outputs validated with respect to both prismatic and rotational parts.     

Effectiveness study of an automated 3D laminography x-ray inspection system in a high-volume–low-mix SMT line

The advent of miniature surface-mount components coupled with increasing lead counts poses tremendous challenges during the assembly of printed circuit boards (PCBs). This is especially true in an electronics manufacturing service (EMS) industry, where the focus has been to increase throughput and first-pass yields at minimum expenditure. Hence, robust inspection systems are required to achieve the objectives of inspecting all the solder joints on a PCB assembly without affecting throughput and of accurately and repeatedly detecting solder-joint-related defects. Conventional inspection technologies are limited in their capability to inspect and detect solder-joint-related defects. However, these limitations have been addressed to a considerable extent by automated 3D laminography x-ray inspection systems. This research effort ascertained the effectiveness of an automated 3D laminography x-ray inspection system from a statistical and assembly perspective. The results of this investigation were analyzed and continuous improvement measures were initiated and employed to improve the performance of the automated 3D laminography x-ray inspection system and, subsequently, of the surface-mount technology (SMT) line.     

A blackboard-based process planning system for the surface mount manufacture of PCBs

This paper describes a real-time computer-aided process planning (CAPP) system for printed circuit board (PCB) assembly using surface mount technology. The prototype, dynamic, realtime CAPP system described uses a blackboard to integrate multiple knowledge sources (knowledge bases) in implementing the process planning procedure. The CAPP system is implemented using the expert system environment (ESE) and structured query language (SQL). The system uses two subsystems (knowledge bases). They are a planning subsystem which performs the static process planning task and a dynamic information processing subsystem which considers the real-time changes on the shop floor and routes the PCB assembly flow. The integrated system developed generates process plans that can be implemented in real time. The use of the blackboard concept for CAPP architecture is unique and well suited for this task.     

An adhesive selection advisor for PCB assembly using surface mount technology

The interrelationships that exist in the manufacturing processes associated with the surface mount manufacture of printed circuit boards (PCBs) are complex and varied. Proper understanding of the relationships between the variables in a surface mount technology (SMT) process are critical for achieving effective process control and high yields. One aspect of the complex relationship is the selection and dispensing of adhesives for the wave soldering of surface mount components on a PCB.The quantitative and repeatable dispensing of adhesive dots is critical to providing adequate process control for attaching components including chip resistors, capacitors, and small outline type transistors to the wave solder side of a PCB. Variables that need to be considered include facility temperature, humidity, size and types of components used on the PCB, adhesive properties, type of dispenser used, curing requirements, and the soldering time and temperature,A knowledge-based approach which considers these relationships is described. Developed in PROLOG, this stand alone adhesive selection advisor is capable of guiding the user in the selection of the proper adhesive and providing dispenser related information. The factors considered include facility temperature, material property requirements, productivity measures including yield, and the process used to dispense the adhesive. The system also functions as a database for adhesive related properties and as an on-line installation and maintenance manual for the adhesive dispenser. Twenty-one different commerically available adhesives and two types of dispensers (air over and positive displacement) have been considered in this research.     

Progressive refinement of 3-d images using coded binary trees: algorithms and architecture

An encoding/decoding technique and a computer architecture for progressive refinement of 3-D images is suggested. The method is based on a binary tree representation of grey-level images. A scheme to transform an N × N × N image array into a sequence of at most N × N × N elements is given. As more elements of the sequence are scanned finer resolution representations of the image are obtained. The proposed architecture, which is suitable for VLSI implementation, performs the transformations between the image and its encoding using O(log N) processors and in time and space proportional to the image size.