Planning the GMAW process by constraint propagation

Although the gas metal arc welding (GMAW) process is widely used for joining metals, its planning is still a cumbersome task. The planning procedure involves many complex interrelationships among the process variables and depends heavily on empirical knowledge. Therefore, a solution method that allows a convenient way to represent the domain knowledge and evaluate the process variable relationships is needed. Further, the lack of a strong domain theory to quantify these interrelationships is a deficiency in the planning of the GMAW process. This paper presents a solution method that overcomes this deficiency and introduces a convenient knowledge representation scheme. The solution method considers the planning procedure to be a constraint satisfaction problem (CSP). The AC-4 algorithm is used to obtain arc consistency among nodes in the constraint network and the PC-4 algorithm is applied to obtain path consistency in the network. A modified version of the AC-4 algorithm is developed to reduce the search space and correspondingly reduce the computation time. An example is presented to demonstrate the capability of the method and its potential to reduce lead time.     

The Quest for a Unified Economics

Max Weber (1864–1920) and Joseph Alois Schumpeter (1883–1950)shared roughly the same vision of economics: a unified disciplinecombining economic theory, economic history and economic sociology.They both devoted most of their academic lives to the realizationof this vision. The editors of Industrial and Corporate Changehave organized this review symposium as an occasion to reflecton the present theoretical significance of these two thinkers.Within the last fifteen years, it is clear that the quest fora unified economics, though still unrealized, is once againan important goal to many people working at the intersectionsof economics, history and sociology. In this essay, I will describethe visions held by Schumpeter and Weber, and using WolfgangStolper's book on Schumpeter and Stephen Kalberg's book on Weberas guides, I will contrast the two distinct paths that Schumpeterand Weber took in their quests to achieve a unified discipline.I will conclude with a brief evaluation of how the two booksunder review contribute to an economics so envisioned.     

Case-based reasoning assisted explanation of genetic algorithm results

Abstract

This paper describes a system for explaining solutions generated by genetic algorithms (GAs) using tools developed for case-based reasoning (CBR). In addition, this work empirically supports the building block hypothesis (BBH) which states that genetic algorithms work by combining good sub-solutions called building blocks into complete solutions. Since the space of possible building blocks and their combinations is extremely large, solutions found by GAs are often opaque and cannot be easily explained. Ironically, much of the knowledge required to explain such solutions is implicit in the processing done by the GA. Our system extracts and processes historical information from the GA by using knowledge acquisition and analysis tools developed for case-based reasoning. If properly analysed, the resulting knowledge base can be used: to shed light on the nature of the search space; to explain how a solution evolved; to discover its building blocks; and to justify why it works. Such knowledge about the search space can be used to tune the GA in various ways. As well as being a useful explanatory tool for GA researchers, our system serves as an empirical test of the building block hypothesis. The fact that it works so well lends credence to the theory that GAs work by exploiting common genetic building blocks.     

Optimal injection velocity profiling

Recently, manufacturers of thermoplastic injection moulding machines have developed controllers with programmable velocity control. The speed of the ram can typically be varied in as many as ten zones during the injection process to establish a velocity profile. This velocity profile however, is determined by trial and error. Some controller manufacturers have made claims about injection velocity profiling, however, actual experimental data is not available to confirm them. In this paper, some experiments were conducted in order to verify the effectiveness of these claims. The results of these experiments indicate that injection velocity control has little effect on reducing or eliminating the problems for which the claims are made.     

PERSONALITY CORRELATES OF FREE-ASSOCIATIVE SEX RESPONSES TO DOUBLE-ENTENDRE WORDS.

SEX RELATED RESPONSES GIVEN IN FREE ASSOCIATION TO DOUBLE-ENTENDRE WORDS WERE RELATED TO THE PERSONALITY VARIABLES OF SEX GUILT, NEED FOR HETEROSEXUALITY, AND THE SOCIAL DESIRABILITY RESPONSE SET. TESTING WAS CONDUCTED INDIVIDUALLY. VARIABLES OF SEX GUILT, SEXUAL MOTIVE STRENGTH, AND SOCIAL DESIRABILITY RESPONSE TENDENCY WERE MEASURED RESPECTIVELY BY THE MOSHER FORCED-CHOICE GUILT SCALE, THE EPPS, AND THE MARLOW-CROWNE SOCIAL DESIRABILITY SCALE. RESULTS INDICATED A POSITIVE RELATIONSHIP BETWEEN NEED FOR HETEROSEXUALITY AND ASSOCIATIVE SEXUAL RESPONSES, AND A NEGATIVE RELATIONSHIP BETWEEN SEX GUILT AND SEXUAL RESPONSIVITY. CONTRARY TO PREDICTION, ASSOCIATIVE SEXUAL RESPONSES WERE UNRELATED TO THE SOCIAL DESIRABILITY RESPONSE TENDENCY. DATA ALSO SHOWED A SIGNIFICANT NEGATIVE RELATION BETWEEN SEX GUILT AND SEXUAL NEED STRENGTH, AND A LOW POSITIVE RELATION BETWEEN SEX GUILT AND SOCIAL DESIRABILITY. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Sintering of Inhomogeneous Binary Powder Mixtures

A geometric model for the sintering of inhomogeneous, binary powder mixtures having a large size ratio is presented. The model is demonstrated for a hypothetical mixture in which the heterogeneity is described by a normal distribution function. The model is demonstrated for the case of the fine fraction sintering only and for the case of both components sintering. Relative to the prediction for the homogeneous mixture, shrinkage is observed to be either "enhanced,""retarded," or the same, depending on the compositional limits of heterogeneity and the level of sintering.     

Statistical Evaluation of Data for Detecting Adulteration of California Navel Orange Juice

Compositional data from California early-, mid-, and late-season navel orange juice, concentrate and two-stage pulpwash were analyzed by various statistical techniques (ratios, regression, chi-square, Linear combination, and discriminant analysis) for detecting adulteration. These techniques were evaluated according to applicability for detecting three types of adulteration: (1) addition of sugar and/or citric acid, (2) addition of excess or unauthorized pulpwash, and (3) addition of other constituents intended to mask the dilution. Most parameters were significantly affected by time of harvest following commercial maturity. Two-stage pulpwash showed small but significant differences from corresponding single strength juice. Product differences were of about the same magnitude as the differences due to harvest date.