Abstract: The performance of subband coders relies heavily on the ability of the analysis system to isolate contiguous frequency bands of speech. Typically analysis/synthesis systems introduce aliasing and short-time spectral distortion. A variety of approaches have been introduced in the past that allow some or all of these sources of degradation to be removed. This paper presents a unifying framework which allows these many diverse approaches to be compared and contrasted in terms of the fundamental design issues. In particular, this framework allows the critical issues of aliasing, spectral distortion, efficiency, stability, etc. that are important in a practical system to be specifically addressed. This, in turn, leads to a new understanding of the relationships among many published approaches. But more important, it leads to the definition of many new realizations as well, particularly in the area of exactly-reconstructing analysis/synthesis systems based on maximally decimated filter banks.

Abstract: The variance derived from the images of cyclic bar patterns can be used to determine the modulation transfer function(MTF) of an imaging system. Unlike most MTF methods, it is applicable even when the imaging system undersamples the test object and generates aliasing errors. The validity of the variance method in the presence of aliasing is established theoretically and by computer simulation.

Abstract: A constraint is a relation among program variables that is maintained throughout execution. Type declarations and a very general form of aliasing can be expressed as constraints. A proof system based upon the interpretation of Hoare triples as temporal logic formulas is given for reasoning about programs with constraints. The proof system is shown to be sound and relatively complete, and example program proofs are given.

Abstract: : For the VLSI design to be reliably produced as a working chip, various features on the chip must be separated by minimum distances to ensure the proper operation of transistors and interconnections. The design rule checker program verifies that these and other geometric constraints are satisified and signals an error if it finds two features that violate the design rules. For a chip composed of millions of rectangles, design rule checking is a time-consuming process which cannot be done entirely within the primary memory of many computers. This thesis presents an efficient algorithm for finding the connected components of rectangles in the plane using a machine model which incorporates the secondary disk memory where the VLSI design is stored. By running this algorithm simultaneously on each layer of a VLSI chip design, a design rule checker can determine which features of a chip design are electrically equivalent, i.e., are effectively part of the same wire. The determination of electrical equivalence allows the design rule checker to avoid reporting the many aliasing errors which occur when two electrically equivalent features are mistaken for electrically distinct features. For example, two wires might be too close together, but if they are actually the same wire, it does not matter.

Abstract: An experimental digital multifrequency receiver was designed and implemented to verify the hypothesis that aliasing techniques can be used to improve the performance-cost ratio of these systems. The receiver employs specific spectral analysis and digit decoding algorithms to take advantage of the aliasing fold-over in order to reject voice-simulated digits. An approximate 2:1 reduction in computational requirement is obtained. Rigorous tests were carried out to verify that computational benefits are not obtained at the expense of degraded performance.

Abstract: The paper deals with some errors of modelling of digital measuring systems, especially the errors due to aliasing, that means if the samplingtheorem is not fulfilled. Theese errors are typical appearing in measuring systems, because application of microprocessors requires sensors with direct digital output. Then a low-pass-filtering before a/d-conversion often is not possible. In the paper methods of calculation of theese errors are shown as well as arrangements for error-reduction.

Abstract: We present a different style of axiomatic definition for programming languages. It is oriented toward imperative languages, such as Algol 68, that do not distinguish between statements and expressions. Rather than basing the logic on a notion of pre- or postcondition, we use the value of a programming language expression as the underlying primitive.A number of language constructs are examined in this framework. We argue that this style of definition gives us a significantly different view of the notion of “easy axiomatixability.” Side effects in expressions as well as aliasing between variables are shown to be “easily axiomatizable” in our system.