A redundant arithmetic CORDIC system with a unit scale factor

The CORDIC algorithm for the calculation of trigonometric functions has traditionally suffered from two problems; speed, and the necessity to pre-scale the inputs. The speed problem is overcome to a large extent by the introduction of redundant number systems which have been shown by others. Here we show a new CORDIC system which has a unit scale factor that can be ignored. The unit scale factor is achieved by rotating the vector in 3 dimensional space in a manner which scales its projection onto the X-Y plane by the reciprocal of the overall scale factor. This new technique takes the same number of cycles as the standard CORDIC algorithm, with only marginally slower cycle times than the redundant system of Takagi. The system is shown to be entirely compatible with redundant number system implementations of the CORDIC algorithm

Lunar lander conceptual design

This paper is a first look at the problems of building a lunar lander to support a small lunar surface base. A series of trade studies was performed to define the lander. The initial trades concerned choosing number of stages, payload mass, parking orbit altitude, and propellant type. Other important trades and issues included plane change capability, propellant loading and maintenance location, and reusability considerations. Given a rough baseline, the systems were then reviewed. A conceptual design was then produced. The process was carried through only one iteration. Many more iterations are needed. A transportation system using reusable, aerobraked orbital transfer vehicles (OTV's) is assumed. These OTV's are assumed to be based and maintained at a low Earth orbit (LEO) space station, optimized for transportation functions. Single- and two-stage OTV stacks are considered. The OTV's make the translunar injection (TLI), lunar orbit insertion (LOI), and trans-Earth injection (TEI) burns, as well as midcourse and perigee raise maneuvers

So happy for your loss: Consumer schadenfreude increases choice satisfaction

Consumers often feel schadenfreude, an emotion reflecting an experience of pleasure over misfortunes of another. Schadenfreude has found wide use in advertising, but its actual consequences for consumers have not been thoroughly documented. The present research investigates the effect of schadenfreude on consumers' satisfaction with choices they have made. Building on the feelings‐as‐information theory, the authors posit that consumers take their positive feelings of schadenfreude over another's unrelated bad purchase as positive information about their own choices, and through such misattribution become more satisfied with their own choices. Three experiments show that feeling schadenfreude over another consumer's bad purchase makes consumers more satisfied with their own choices (Study 1), regardless of whether the other's bad purchase is in the same or in a different product category as one's own choice (Study 2), but only so long as consumers are not aware that they are engaging in misattribution (Study 3). The present research contributes to the literature on schadenfreude and feelings‐as‐information theory. Its findings may be used by marketers aiming to exert an unconscious influence on consumer satisfaction

Highly non-linear encoders for current mode multiple-valued logic

This paper describes the use of highly non-linear encoders to provide low power Current Mode Multiple Valued Logic (CMMVL) circuits. A maximum function is shown, that consumes much less power than previously reported circuits. The encoding system is based upon using a single transistor between the encoder output and ground to provide a 'very negative' signal that overrides any other connection to the output node

An analysis of processor resource models for use in performance prediction

With the increasing sophistication of both software and hardware systems, methodologies to analyse and predict system performance is a topic of vital interest. This is particularly true for parallel systems where there is currently a wide choice of both architectural and parallelisation options; and where the costs are likely to be high. Performance data is vital to a diffuse range of users including; system developers, application programmers and tuning experts. However, the level of sophistication and accuracy required by each of these users is substantially different. In this paper characterisation based technique is described (considering both application and hardware resources) which addresses these issues directly. Initially, a framework is described for characterisation based approaches. A classification scheme is used to illustrate differences in the level of sophistication and detail in which the underlying resource models are specified. Finally, verification is provided of the characterisation techniques applied to several application kernels on a MIMD system. The performance predictions and error bounds resulting from the level of resource specification are also discussed

An introduction to the CHIP3S language for characterising parallel systems in performance studies

A characterisation toolset, Characterisation Instrumentation for Performance Prediction of Parallel Systems (CHIP3S), for predicting the performance of parallel systems is presented in this report. In this toolset expert knowledge about the performance evaluation techniques is not required as a prerequisite for the user. Instead a declarative approach to the performance study is taken by describing the application in a way that is both intuitive to the user, but can also be used to obtain performance results. The underlying performance related characterisation models and their evaluation processes are hidden from the user. This document describes the special purpose language, and the evaluation system, that form the core of the CHIP3S toolset. Amongst the aims of the toolset is the support of characterisation model reusability, ease of experimentation, provide different levels of prediction accuracy, and support of different levels of characterisation model abstraction

Three dimensional CORDIC with reduced iterations

This paper describes a modification to the three dimensional CORDIC algorithm using an approximation of the Taylor series. The modification has the potential to reduce the number of iterations required for a three dimensional CORDIC operation by at least 25 percent. The approach used is based upon a modification of the two dimensional CORDIC algorithm originally suggested by H.M Ahmed

Characterising computational kernels : a case study

We describe the characterisation of an application kernel on a parallel system of two processors. The application kernel is a one-dimensional Fast Fourier Transform (FFT) and the processors used are two T800 transputers. Analytical expressions for the "execution time" for a single and two processors are discussed and used to obtain the performance measure

An introduction to the layered characterisation for high performance systems

A toolset for performance analysis of parallel systems, PACE, is presented in this report. In this toolset expert knowledge about the performance evaluation techniques is not required as a prerequisite for the user. Instead a declarative approach to the performance study is taken by describing the application in a way that is both intuitive to the user, but can also be used to obtain performance results. The underlying performance related characterisation models and their evaluation processes are hidden from the user. This document describes the special purpose language, and the evaluation system, that form the core of the PACE toolset. Amongst the aims of the toolset is the support of characterisation model reusability, ease of experimentation, provide different levels of prediction accuracy, and support of different levels of characterisation model abstraction