Improving Pareto Optimal Designs Using Genetic Algorithms

Abstract: Pareto optimal designs are the best designs that can be produced for a given problem formulation for a given set of criteria when the criteria are not combined in any way. If the goal is to improve the performance in those criteria, then it is possible to manipulate the problem formulation to achieve an improvement. The approach adopted is to encode the formulation in a genetic algorithm and to allow the formulation to evolve in the direction of improving Pareto optimal designs. A set of rules (in the form of a shape grammar), the execution of which produces a design, is encoded as the genes in a genetic algorithm. However, the rule set is allowed to evolve, not just the order of execution of rules. We present an example demonstrating both the approach and its utility in improving Pareto optimal designs.     

Schallanalyse Neuronale Repräsentation des Hörvorgangs als Basis

Zusammenfassung Anlehnend an die überlegenheit des Menschen bei der Differenzierung von Schallsignalen, verglichen mit dem aktuellen Stand der Technik, widmet sich dieser Artikel dem Aufzeigen der Mechanismen und Vorg?nge, die sich bei der Verarbeitung von mechanischem Schall in Nervenimpulse innerhalb des Ohrs vollziehen, als Basis für eine m?gliche technische Nachbildung, z.B. zur Erkennung von Tonh?hen in Musik.     

Oxidation of nanostructured Ti films produced by low energy cluster beam deposition: An X-ray Photoelectron Spectroscopy characterization

We used in-situ X-ray Photoelectron Spectroscopy (XPS) to study the oxidation process of a cluster-assembled metallic titanium film exposed to molecular oxygen at room temperature. The nanostructured film has been grown on a Si(111) substrate, in ultra high vacuum conditions, by coupling a supersonic cluster beam deposition system with an XPS experimental chamber. Our results show that upon in-situ oxygen exposure Ti^3 + is the first oxidation state observed, followed by Ti^4 +, whereas Ti^2 + is practically absent during the whole process. Our results compare well with the existing literature on Ti films produced using other techniques.     

Wood pellets production costs and energy consumption under different framework conditions in Northeast Argentina

The development of cleaner and renewable energy sources are needed in order to reduce dependency and global warming. Wood pellets are a clean renewable fuel and has been considered as one of the substitutes for fossil fuels. In Argentina, large quantities of sawmill residues are still unused and wood pellets production could be seen as both, as an environmental solution and an extra economical benefit. The general aim of this study was to determine the wood pellets production costs and energy consumption under different framework conditions in northeast Argentina. The specific costs of wood pellets for the different scenarios showed relative lower costs comparing to the ones reported in other studies, ranging from 35 to 47 €/Mg_pellets. Raw material costs represented the main cost factor in the calculation of the total pellets production costs. A lower specific production cost was observed when 50% of the raw material input was wood shavings. The specific electricity consumption per metric ton of pellet was lower in scenarios with higher production rate. Lower heat energy consumption was observed in scenarios that have a mixed raw material input. The most promising framework condition for Northeast Argentina, in terms of costs effectiveness and energy consumption could be acquired with production rates of 6 Mg/h with sawdust and wood shavings as raw material. However, simultaneous increment of the electricity by 50% and raw material price by 100% may increase the specific costs up to 50%.     

Purpose and function in a collaborative CAD environment

In a multidisciplinary design environment, such as the architecture, engineering and construction (AEC) domain, the various designers will have their own concepts and representations of the design object making communication in such an environment a complex task. Computer-aided design (CAD) modelling is seen as the vehicle for interdisciplinary communication and integration. However, this paper stresses the need for a multiple view approach based upon an assumption that different views of an object are based on different functional contexts. The paper demonstrates that an understanding of concepts such as function, purpose and intent is critical since the representation of the functional properties of design objects is the underlying basis for the formation of different representations and the coordination of these representations. The paper puts forward definitions for function and purpose which allow for the representation of these properties of a design object and the communication of intent and effects.     

Agent-Based Interoperability without Product Model Standards

Abstract:   This article describes using agents in the exchange of industrial product data when predefined translators are not available. A major problem with standard translators is that a seamless data transfer instantly fails when not every translator implements a mapping into or from the standard format. This is frequently the case for large design projects that involve the use of a multitude of heterogeneous tools, possibly in evolving configurations over time. The agent-based approach developed and presented in this article aims to flexibly provide product models in a form adapted to the needs of the particular tools when there is no prior agreement on a common data format. Experiments show the feasibility of this approach as well as its efficacy and efficiency.     

Interpretation in design: modelling how the situation changes during design activity

This paper presents a model of the way that designers move between situations when interpreting during design activity. Three hypotheses are presented that arise from this model: that designers change their situation during interpretation, that small changes in a source can lead to large changes in the representation and that changes to the situation have their origins in the experience of the designer. The paper demonstrates how this internal movement between situations can be computationally implemented using three examples. The systems implemented demonstrate the way that interpretation can lead to changes in the situation and present an example of how the changes to a designer’s situation can be guided by past experiences.