Quantitative analysis of multi-periodic supply chain contracts with options via stochastic programming

We propose a stochastic programming approach for quantitative analysis of supply contracts, involving flexibility, between a buyer and a supplier, in a supply chain framework. Specifically, we consider the case of multi-periodic contracts in the face of correlated demands. To design such contracts, one has to estimate the savings or costs induced for both parties, as well as the optimal orders and commitments. We show how to model the stochastic process of the demand and the decision problem for both parties using the algebraic modeling language AMPL. The resulting linear programs are solved with a commercial linear programming solver; we compute the economic performance of these contracts, giving evidence that this methodology allows to gain insight into realistic problems.stochastic programming; supply contract; linear programming; modeling software; decision tree

New understanding of the shape-memory response in thiol-epoxy click systems: towards controlling the recovery process

Our research group has recently found excellent shape-memory response in “thiol-epoxy” thermosets obtained with click-chemistry. In this study, we use their well-designed, homogeneous and tailorable network structures to investigate parameters for better control of the shape-recovery process. We present a new methodology to analyse the shape-recovery process, enabling easy and efficient comparison of shape-memory experiments on the programming conditions. Shape-memory experiments at different programming conditions have been carried out to that end. Additionally, the programming process has been extensively analysed in uniaxial tensile experiments at different shape-memory testing temperatures. The results showed that the shape-memory response for a specific operational design can be optimized by choosing the correct programming conditions and accurately designing the network structure. When programming at a high temperature (T » Tg), under high network mobility conditions, high shape-recovery ratios and homogeneous shape-recovery processes are obtained for the network structure and the programmed strain level (eD). However, considerably lower stress and strain levels can be achieved. Meanwhile, when programming at temperatures lower than Tg, considerably higher stress and strain levels are attained but under low network mobility conditions. The shape-recovery process heavily depends on both the network structure and eD. Network relaxation occurs during the loading stage, resulting in a noticeable decrease in the shape-recovery rate as eD increases. Moreover, at a certain level of strain, permanent and non-recoverable deformations may occur, impeding the completion and modifying the whole path of the shape-recovery process.Postprint (author's final draft

The IMPRESS DDT: a database design toolbox based on a formal specification language

The Database Design Tool prototype is being developed in the IMPRESS project (Esprit project 6355). The IMPRESS project started in May 1992 and aims at creating a low-level storage manager tailored for multimedia applications, together with a library of efficient operators, a programming environment, high-level design tools and methodology. The DDT is part of this last effort.\ud \ud The project focuses on the field of Technical Information Systems, where there is a need for tools supporting modeling of complex objects. Designers in this field usually use incremental design or step by step prototyping, because this seems to be best suited for users coping with complexity and uncertainty about their own needs or requirements. The IMPRESS DDT aims at supporting the database design part of this process

The Use of Metaphors as a Parametric Design Teaching Model: A Case Study

Teaching methodologies for parametric design are being researched all over the world, since there is a growing demand for computer programming logic and its fabrication process in architectural education. The computer programming courses in architectural education are usually done in a very short period of time, and so students have no chance to create their own designs. This paper describes a course in which metaphors are used as a teaching methodology in parametric design, in order to let students create their own designs and learn the basic elements of parametric programming language in a short period of time with deductive reasoning. In this course, it was intended to teach visual programming language to undergraduates. Advancing under the metaphor theoretical framework, the students obtained experience in achieving form-finding process for their projects in accord with the certain constraints. Using this methodology, the students, who experienced all design stages from 3D modeling to the digital fabrication, additionally were able to develop their ability for versatile thinking and the use of more than one tool in combination, in the early years of their architectural education

Simplifying the construction of domain-specific automatic programming systems: The NASA automated software development workstation project

An overview is presented of the Automated Software Development Workstation Project, an effort to explore knowledge-based approaches to increasing software productivity. The project focuses on applying the concept of domain specific automatic programming systems (D-SAPSs) to application domains at NASA's Johnson Space Center. A version of a D-SAPS developed in Phase 1 of the project for the domain of space station momentum management is described. How problems encountered during its implementation led researchers to concentrate on simplifying the process of building and extending such systems is discussed. Researchers propose to do this by attacking three observed bottlenecks in the D-SAPS development process through the increased automation of the acquisition of programming knowledge and the use of an object oriented development methodology at all stages of the program design. How these ideas are being implemented in the Bauhaus, a prototype workstation for D-SAPS development is discussed

Authoring a Web‐enhanced interface for a new language‐learning environment

This paper presents conceptual considerations underpinning a design process set up to develop an applicable and usable interface as well as defining parameters for a new and versatile Computer Assisted Language Learning (CALL) environment. Based on a multidisciplinary expertise combining Human Computer Interaction (HCI), Web‐based Java programming, CALL authoring and language teaching expertise, it strives to generate new CALL‐enhanced curriculum developments in language learning. The originality of the approach rests on its design rationale established on the strength of previously identified student requirements and authoring needs identifying inherent design weaknesses and interactive limitations of existing hypermedia CALL applications (Hémard, 1998). At the student level, the emphasis is placed on three important design decisions related to the design of the interface, student interaction and usability. Thus, particular attention is given to design considerations focusing on the need to (a) develop a readily recognizable, professionally robust and intuitive interface, (b) provide a student‐controlled navigational space based on a mixed learning environment approach, and (c) promote a flexible, network‐based, access mode reconciling classroom with open access exploitations. At the author level, design considerations are essentially orientated towards adaptability and flexibility with the integration of authoring facilities, requiring no specific authoring skills, to cater for and support the need for a flexible approach adaptable to specific language‐learning environments. This paper elaborates on these conceptual considerations within the design process with particular emphasis on the adopted principled methodology and resulting design decisions and solutions

Emergent design and image processing : a case study

Thesis (S.M.)--Massachusetts Institute of Technology, Program in Media Arts & Sciences, 1999.Includes bibliographical references (p. 97-99).The digital revolution which has changed so many other aspects of modem life has yet to profoundly affect the working process of visual artists and designers. High-quality digital design tools exist, but they provide the user with an improved traditional design process, not a radically new way of designing. Conventional digital design tools are useful, but when design software emulates a paintbrush or photostudio many powerful possibilities of the computational medium are overlooked. This thesis explores emergent design, a design methodology based on a new process, enhanced interactive genetic programming. The emergent design methodology and tools allow designers to effectively create procedural design solutions (design solutions that take the form of a procedure or program) in a way that requires little or no programming on the part of the designer. The use of preliminary fitness functions in the interactive genetic programming process allows the designer to specify heuristics to guide the search and manage the complexity of the interactive genetic programming task. This document is structured in the form of a case study, in which the enhanced genetic programming process and emergent design methodology are described through their application to the specific problem of developing procedural image filters for still and moving images. Two interactive genetic programming systems for image filter evolution are described, GPI and evolution++, along with the Sol programming language that was used to create them. Results from the implementation and use of GPI and evolution++ are presented, including a number of filtered images and image sequences. These results suggest that fitness-agent enhanced interactive genetic programming and the emergent design methodology may play a useful role in the visual design process, allowing designers to explore a wider range of options with greater ease than is possible through a traditional, procedural, or conventional genetic programming design process.Richard W. DeVaul.S.M

Designing optimal mixtures using generalized disjunctive programming: Hull relaxations

A general modeling framework for mixture design problems, which integrates Generalized Disjunctive Programming (GDP) into the Computer-Aided Mixture/blend Design (CAMbD) framework, was recently proposed (S. Jonuzaj, P.T. Akula, P.-M. Kleniati, C.S. Adjiman, 2016. AIChE Journal 62, 1616–1633). In this paper we derive Hull Relaxations (HR) of GDP mixture design problems as an alternative to the big-M (BM) approach presented in this earlier work. We show that in restricted mixture design problems, where the number of components is fixed and their identities and compositions are optimized, BM and HR formulations are identical. For general mixture design problems, where the optimal number of mixture components is also determined, a generic approach is employed to enable the derivation and solution of the HR formulation for problems involving functions that are not defined at zero (e.g., logarithms). The design methodology is applied successfully to two solvent design case studies: the maximization of the solubility of a drug and the separation of acetic acid from water in a liquid-liquid extraction process. Promising solvent mixtures are identified in both case studies. The HR and BM approaches are found to be effective for the formulation and solution of mixture design problems, especially via the general design problem