A Simplified Method to Calculate Failure Times in Fault-Tolerant Systems

A simplified method is presented to calculate moments of failure time and residual lifetime of a fault-tolerant system. The method is based on recent results in queueing theory. Its effectiveness is illustrated by considering a dual repairable system from the literature

TWENTY QUESTIONS FOR DOCUMENT CLASSIFICATION

Documents – manuscripts, books, magazines, newspapers, sheet music, circuit diagrams, checks, web pages, email attachments, music- CDs, videos, and cuneiform - mirror the culture of the time and serve as the primary source of historical record. Although it seems natural to classify documents according to format before examining their content, form and function are often intertwined. The design of a document interpretation system must take both into consideration. What are the essential parameters of a document interpretation system? What needs to be known before undertaking the design or purchase of such a system? What is the interrelationship of the client, the document, and the desired information? In other words, what is the range of issues of possible interest to our research community? In order to highlight the tacit assumptions implicit in the document analysis literature, we will start with tabula rasa and invite the workshop participants to join us in a game of Twenty Questions

Segmenting Tables via Indexing of Value Cells by Table Headers

Correct segmentation of a web table into its component regions is the essential first step to understanding tabular data. Our algorithmic solution to the segmentation problem relies on the property that strings defining row and column header paths uniquely index each data cell in the table. We segment the table using only “logical layout analysis” without resorting to any appearance features or natural language understanding. We start with a CSV table that preserves the 2- dimensional structure and contents of the original source table (e.g., an HTML table) but not font size, font weight, and color. The indexing property of table headers implies a four-quadrant partitioning of the table about a minimum index point. The algorithm finds the index point through an efficient guided search. Experimental results on a 200-table benchmark demonstrate the generality of the algorithm in handling a variety of table styles and forms

HIERARCHICAL REPRESENTATION OF OPTICALLY SCANNED DOCUMENTS

The objective of the research to be pursued is to develop a schema for representing raster-digitized (scanned) documents, The representation is to retain not only the spatial structure of a printed document, but should also facilitate automatic labeling of various components, such as text, figures, subtitles, and figure captions, and allow the extraction of important relationships (such as reading order) among them. Intended applications include (1) data compression for document transmission and archival, and (2) document entry, with out rekeying, into editing, formatting, and information retrieval systems

Forecasting Reject Rate of Tested LSI Chips

The reject rate of LSI chips due to incomplete fault coverage of the tests is the fraction of faulty chips, among the chips that pass the tests. This reject rate, which is a measure of the tested chip quality, contributes to the field returns. It is, however, difficult to determine the tested chip quality from the field return data which may also include rejects due to handling damages, infant mortality, etc. Also, a large number of chips must be in use in the field before an adequate amount of field return data can be obtained. This paper gives a method of forecasting the reject rate from the test data alone before any field trials are made

On Combinational Networks with Restricted Fan-Out

Fan-out-free networks of AND, OR, NOT, EXOR, and MAJORITY gates are considered. Boolean functions for which such networks exist are defined to be fan-out free. The paper solves the following problems regarding the fan-out-free networks and functions. 1) Characterization of the class of fan-out-free functions: The characterization given is constructive in the sense that if a given function is fan-out free one obtains a fan-out-free network to realize it. 2) Counting the class of fan-out-free functions: After establishing a correspondence between a fan-out-free function and a normalized network realizing it, a series of formulas are developed to count distinct normal networks for any subset of the five gates mentioned above. 3) Fault Diagnosis: Methods are developed to detect multiple faults and to locate single faults in arbitrary fan-out-free networks

Testability Analysis of Synchronous Sequential Circuits Based On Structural Data

Bounds on test sequence length can be used as a testability measure. We give a procedure to compute the upper bound on test sequence length for an arbitrary sequential circuit. We prove that the bound is exact for a certain class of circuits. Three design rules are specified to yield circuits with lower test sequence bounds

Forecasting Reject Rate of Tested LSI Chips

The reject rate of LSI chips due to incomplete fault coverage of the tests is the fraction of faulty chips, among the chips that pass the tests. This reject rate, which is a measure of the tested chip quality, contributes to the field returns. It is, however, difficult to determine the tested chip quality from the field return data which may also include rejects due to handling damages, infant mortality, etc. Also, a large number of chips must be in use in the field before an adequate amount of field return data can be obtained. This paper gives a method of forecasting the reject rate from the test data alone before any field trials are made

Decoding Substitution Ciphers by Means of Word Matching with Application to OCR

A substitution cipher consists of a block of natural language text where each letter of the alphabet has been replaced by a distinct symbol. As a problem in cryptography, the substitution cipher is of limited interest, but it has an important application in optical character recognition. Recent advances render it quite feasible to scan documents with a fairly complex layout and to classify (cluster) the printed characters into distinct groups according to their shape. However, given the immense variety of type styles and forms in current use, it is not possible to assign alphabetical identities to characters of arbitrary size and typeface. This gap can be bridged by solving the equivalent of a substitution cipher problem, thereby opening up the possibility of automatic translation of a scanned document into a standard character code, such as ASCII. Earlier methods relying on letter n-gram frequencies require a substantial amount of ciphertext for accurate n-gram estimates. A dictionary-based approach solves the problem using relatively small ciphertext samples and a dictionary of fewer than 500 words. Our heuristic backtrack algorithm typically visits only a few hundred among the 26! possible nodes on sample texts ranging from 100 to 600 words

Parallel Test Generation With Low Communication Overhead

In this paper we present a method of parallelizing test generation for combinational logic using boolean satisfiability. We propose a dynamic search-space allocation strategy to split work between the available processors. This strategy is easy to implement with a greedy heuristic and is economical in its demand for inter-processor communication. We derive an analytical model to predict the performance of the parallel versus sequential implementations. The effectiveness of our method and analysis is demonstrated by an implementation on a Sequent (shared memory) multiprocessor. The experimental data shows significant performance improvement in parallel implementation, validates our analytical model, and allows predictions of performance for a range of time-out limits and degrees of parallelism