Reconfigurability in space systems : architecting framework and case studies

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2006.Includes bibliographical references (p. 247-257).Reconfigurability in engineered systems is of increasing interest particularly in Aerospace Systems since it allows for resource efficiency, evolvability, and enhanced survivability. Although it is often regarded as a desirable quality for a system, it has traditionally been difficult to quantitatively analyze its effects on various system properties in the early design stage. In order to allow for gaining an in-depth understanding of the various aspects of reconfigurability and its relationship with a system's architecture, a framework encompassing a set of definitions, metrics, and methods has been proposed. Two different modeling schemes, based on Markov models and controls theory, are first developed to show how the states and time aspects of reconfigurable systems can be naturally modeled and studied. An analytical model for quantifying the effect of reconfigurability on mission logistics, specifically spare parts demands, is formulated and it is shown through one specific example that reconfigurable parts can allow for 33-50% mass reduction. The system availability, however, becomes very sensitive to the reliability of the parts. Two case studies are then used for detailed illustration of the application of the developed framework.(cont.) In the first case study, the effect of reconfigurability on a fleet of planetary surface vehicles for a surface exploration mission are analyzed. It is found that a fleet of reconfigurable vehicles can allow for a mass savings of up to 27% and their expected transport capability degradation is almost three times lower as compared to a fleet of non-reconfigurable vehicles. In the second case-study, the reconfiguration of low earth-orbit communication satellite constellations is considered for evolving to higher capacity levels. It is found that reconfiguring a previously deployed constellation can be a viable option only for certain capacity levels and multi-payload launch capability scenarios. In addition to the high level 'ility' perspectives, a lower level design assessment is also carried out through a survey of 33 representative reconfigurable systems. It is found that on average, for commercial items the cost of reconfigurability is 35%, and the average useful state occupancy time is always at least 10 times the reconfiguration time of the system. Based on the illustrative results of the case studies, and generalization of empirical data, a few principles and guidelines for design for reconfigurability are proposed.by Afreen Siddiqi.Ph.D

Operational Research: Methods and Applications

Throughout its history, Operational Research has evolved to include a variety of methods, models and algorithms that have been applied to a diverse and wide range of contexts. This encyclopedic article consists of two main sections: methods and applications. The first aims to summarise the up-to-date knowledge and provide an overview of the state-of-the-art methods and key developments in the various subdomains of the field. The second offers a wide-ranging list of areas where Operational Research has been applied. The article is meant to be read in a nonlinear fashion. It should be used as a point of reference or first-port-of-call for a diverse pool of readers: academics, researchers, students, and practitioners. The entries within the methods and applications sections are presented in alphabetical order

Naval Research Program 2021 Annual Report

NPS NRP Annual ReportThe Naval Postgraduate School (NPS) Naval Research Program (NRP) is funded by the Chief of Naval Operations and supports research projects for the Navy and Marine Corps. The NPS NRP serves as a launch-point for new initiatives which posture naval forces to meet current and future operational warfighter challenges. NRP research projects are led by individual research teams that conduct research and through which NPS expertise is developed and maintained. The primary mechanism for obtaining NPS NRP support is through participation at NPS Naval Research Working Group (NRWG) meetings that bring together fleet topic sponsors, NPS faculty members, and students to discuss potential research topics and initiatives.Chief of Naval Operations (CNO)Approved for public release. Distribution is unlimited.

A business process reengineering framework using the analytic hierarchy process to select a traceability technology for spare parts management in capital-intensive industries

Thesis (MEng)--Stellenbosch University, 2016.ENGLISH ABSTRACT: demand forecasting for spare parts; and inventory warehousing management. Various aspects (including 29 best practices) of BPR are described in order to support the proposed framework. These include criteria for selecting processes to redesign, the role of Information Technology in BPR and typical barriers to eff ective implementation of BPR. The AHP (a multi-criteria decision-making method) is explained in detail, as it facilitates the selection of asset traceability technology. An overview of asset traceability technologies (speci fically barcode technology, Radio Frequency Identi cation (RFID) technology and Global Positioning System (GPS) technology) is also provided, including the description of certain characteristics of each technology. The proposed framework, based on the literature review, serves as a structured guide and consists of two primary parallel elements (referred to as streams), namely the BPR stream and the Change Management stream. The BPR stream encompasses six phases of BPR (Contextualise SPM, Business Process Redesign, Asset Traceability Technology, Decision-Making, Implement, and Monitor and Evaluate) while the Change Management stream consists of three stages (Unfreeze State, Change State and Refreeze State). The framework is validated through face validation via semi-structured interviews with participants forming a panel of experts involved in and familiar with SPM and asset traceability technology. According to the expert panel, the proposed framework satisfies achievement of the desired framework attributes, namely (i) Generic and adaptable, (ii) Holistic and comprehensive, (iii) Structured and objective- or outcome-oriented and (iv) Practical. In addition, the expert panel perceived the framework to be useful, easy to use and understandable. However, recommendations were proposed to further improve the framework, including the addition of a scoping and objectives section and the expansion of the Change Management element.AFRIKAANSE OPSOMMING: Onderdele is noodsaaklik vir die e ektiewe bedryf van 'n kapitaal-intensiewe organisasie en maak, tesame met materiaalverbruik, ongeveer 50% uit van 'n tipiese instandhoudingsbegroting. Ten spyte van die relatief groot hoeveelheid literatuur beskikbaar oor onderdele, pas min maatskappye egter ordentlike strukturele, feitlike en kwantitatiewe Onderdelebestuur toe. Geïntegreerde benaderings om onderdele te bestuur, sowel as om teoretiese modelle te ondersteun met praktiese riglyne, word benodig ten einde die gaping tussen navorsing en praktyk te oorbrug. Die studie het voortgevloei uit 'n geleentheid geïdenti seer om prosesse binne Onderdelebestuur te verbeter, spesi ek deur die gebruik van bate opspoorbaarheidstegnologie. 'n Raamwerk word voorgestel wat (i) die Besigheidsproses Hersiening lei deur prosesse binne Onderdelebestuur, met die inagneming van elemente van Veranderingsbestuur, en (ii) die keuse van opspoorbaarheidstegnologie lei vir integrasie binne Onderdelebestuur by kapitaal-intensiewe organisasies (deur die gebruik van die Analitiese Hiërargie Proses). Die navorsing bestaan uit 'n bespreking van Batebestuur, insluitend PAS 55 en ISO 55000 (twee belangrike Batebestuur dokumentreekse) en Veranderings-bestuur, wat 'n noodsaaklike aspek vir implementering is. Vervolgens word Onderdelebestuur, 'n onderafdeling van Batebestuur wat verband hou met onderdele en die fokuspunt van die studie is, aangespreek. Die volgende Onderdelebestuur aspekte word onder andere aangespreek: eienskappe van onderdele en hoe onderdele van ander algemene voorraad verskil; klassi seringskriteria en klassi seringstegnieke; vooruitskatting van die vraag na onderdele; en die bestuur van voorraadvlakke. Verskeie aspekte (insluitend 29 beste praktyke) van Besigheidsproses Hersiening word beskryf ten einde die voorgestelde raamwerk te ondersteun. Dit sluit kriteria in vir die keuse van herontwerpsprosesse, die rol van Inligtingstegnologie in Besigheidsproses Hersiening en tipiese struikelblokke vir die e ektiewe implementering van Besigheidsproses Hersiening. Die Analitiese Hiërargie Proses ('n multi-kriteria besluitnemingsmetode) word in detail verduidelik, aangesien dit die keuse van 'n bate opspoorbaarheidstegnolgie moet fasiliteer. 'n Oorsig van bate pspoorbaarheidstegnolgieë (spesi ek strepieskode tegnologie, Radiofrekwensie Identi kasie (RFID) tegnologie en Globale Posisioneringstelsel (GPS) tegnologie) word ook verskaf, insluitend die beskrywing van sekere eienskappe van elke tegnolgie. Die voorgestelde raamwerk, gebasseer op die literatuurstudie, dien as 'n gestruktureerde gids en bestaan uit twee primêre parallele elemente (wat na verwys word as strome), naamlik die Besigheidsproses Hersiening stroom en die Veranderingsbestuur stroom. Die Besigheidsproses Hersiening stroom vervat ses fases van Besigheidsproses Hersiening (Kontekstualiseer Onderdelebestuur, Besigheidsproses Hersiening, Bate Opspoorbaarheidstegnolgie, Besluitneming, Implementeer, en Monitor en Evalueer) terwyl die Veranderingsbestuur stroom bestaan uit drie stadiums (Ontvries Stadium, Verander Stadium en Hervries Stadium). Die voorgestelde raamwerk word bekragtig deur sigwaarde bekragtiging via semi-gestruktureerde onderhoude met deelnemers wat 'n paneel van deskundiges vorm wat betrokke en vertroud is met Onderdelebestuur en Bate Opspoorbaarheidstegnolgie. Volgens die paneel van deskundiges slaag die voorgestelde raamwerk daarin om die vereiste raamwerk kenmerke te bereik, naamlik (i) Generies en aanpasbaar, (ii) Holisties en omvattend, (iii) Gestruktureerd en doelof uitkomsgeöriënteerd en (iv) Prakties. Boonop het die paneel van deskundiges die raamwerk gesien as nuttig, maklik om te gebruik en verstaanbaar. Aanbevelings was egter voorgestel om die raamwerk verder te verbeter, insluitend die byvoeging van 'n bestek en doelwitte afdeling en die uitbreiding van die Veranderingsbestuur element

Operational Research: methods and applications

This is the final version. Available on open access from Taylor & Francis via the DOI in this recordThroughout its history, Operational Research has evolved to include methods, models and algorithms that have been applied to a wide range of contexts. This encyclopedic article consists of two main sections: methods and applications. The first summarises the up-to-date knowledge and provides an overview of the state-of-the-art methods and key developments in the various subdomains of the field. The second offers a wide-ranging list of areas where Operational Research has been applied. The article is meant to be read in a nonlinear fashion and used as a point of reference by a diverse pool of readers: academics, researchers, students, and practitioners. The entries within the methods and applications sections are presented in alphabetical order. The authors dedicate this paper to the 2023 Turkey/Syria earthquake victims. We sincerely hope that advances in OR will play a role towards minimising the pain and suffering caused by this and future catastrophes