An Integrated Model-Based Approach for Systems Engineering

Systems engineering projects are increasingly complex, and often involve multi-disciplinary teams, different physical locations, and diverse stakeholders. At the early stage of the systems engineering process, systems engineers need to deal with capturing the needs, planning the process, and analyzing early solutions. These activities during early stages have a tremendous impact to all later downstream activities of the development process in term of time-to-market, quality of a system, and final cost. Model-Based Systems Engineering (MBSE), as a model-centric approach, was purposed to support systems engineers to deal with the complexities in developing a system using models. The advantages of implementing MBSE in a project are for example purposed for improving the quality, reducing the risks, increasing the productivity, and improving the communication effectively. However, models are not very useful if they cannot be executed and used for verification and validation purposes. The scope of this thesis focuses on integrating a model-based approach formalized by Systems Modeling Language (SysML) in the three following domains: requirements modeling, tasks and activities scheduling, and behavioral analyzing of a physical system. In the first domain, i.e. requirements modeling, this thesis contributes to the analysis of the impact of changes within requirements with the combination of SysML stereotypes and Design Structure Matrix (DSM) techniques. In the second domain, Design Structure Matrix (DSM) and Differential Evolution algorithm (DDE) techniques allow systems engineers to schedule the development process by minimizing iteration of tasks and increasing concurrency between tasks. In the third domain, techniques from Qualitative Physics, i.e. Dimensional Analysis and Causal ordering, are applied for modeling and simulating the behavior of physical systems.Järjestelmäsuunnitteluprojektit ovat yhä monimutkaisempia ja usein niihin liittyy poikkitieteellisiä tiimejä useissa fyysisissä paikoissa ja erinäisiä sidosryhmiä. Järjestelmäprosessien aikaisessa vaiheessa järjestelmäinsinöörien täytyy kerätä tarpeet, suunnitella prosessi ja analysoida aikaiset ratkaisut. Näillä aikaisen vaiheen toiminnoilla on suuri merkitys myöhempiin kehitysprosessin aktiviteetteihin kuten markkinoille pääsyaikaan, järjestelmän laatuun ja lopulliseen kustannukseen. Mallipohjainen järjestelmäsuunnittelu (MBSE), mallikeskeisenä menetelmänä, oli tarkoitettu tukemaan järjestelmäinsinöörejä käsittelemään monimutkaisuutta kehitettäessä järjestelmää käyttäen malleja (vai malleja käyttävää järjestelmää?). MBSE:n etuja ovat esimerkiksi laadun paraneminen, riskien vähentäminen, tuottavuuden kasvu ja kommunikaation parantaminen tehokkaasti. Toisaalta mallit eivät ole kovin käyttökelpoisia, jos niitä ei voida toteuttaa tai käyttää validointiin tai verifikaatioon. Tämän työn keskittyy mallipohjaisen käytännön, mikä on formalisoitu järjestelmänmallinnuskielellä (SysML), integroimiseen seuraavilla aloilla: vaatimusten mallinnus, tehtävien ja toimintojen aikataulutus ja fyysisten järjestelmien käytösanalyysi. Ensimmäisellä alalla, eli vaatimusten mallinnuksessa, tämä työ edistää vaatimusten muutoksista johtuvaa vaikutusanalyysiä yhdistämällä SysML-stereotyyppi- ja suunnittelun rakennematriisi- (DSM) tekniikoita. Toisella alalla DSM ja differentiaalinen kehitysalgoritmi (DDE) tekniikat mahdollistavat järjestelmäinsinöörien aikatauluttaa kehitysprosessia minimoimalla tehtävien iteroinnin ja lisäämällä tehtävien samanaikaisuutta. Kolmannella alalla kvalitatiivisen fysiikan tekniikoita, kuten dimensioanalyysi ja syy-seuraus analyysi, sovelletaan fyysisten järjestelmien käyttäytymisen mallinnuksessa ja simuloinnissa

A double-decomposition based parallel exact algorithm for the feedback length minimization problem

Product development projects usually contain many interrelated activities with complex information dependences, which induce activity rework, project delay and cost overrun. To reduce negative impacts, scheduling interrelated activities in an appropriate sequence is an important issue for project managers. This study develops a double-decomposition based parallel branch-and-prune algorithm, to determine the optimal activity sequence that minimizes the total feedback length (FLMP). This algorithm decomposes FLMP from two perspectives, which enables the use of all available computing resources to solve subproblems concurrently. In addition, we propose a result-compression strategy and a hash-address strategy to enhance this algorithm. Experimental results indicate that our algorithm can find the optimal sequence for FLMP up to 27 activities within 1 hour, and outperforms state of the art exact algorithms.Comment: This paper has been accepted by PeerJ Computer Science on August 28, 202

Cost Factor Focused Scheduling and Sequencing: A Neoteric Literature Review

The hastily emergent concern from researchers in the application of scheduling and sequencing has urged the necessity for analysis of the latest research growth to construct a new outline. This paper focuses on the literature on cost minimization as a primary aim in scheduling problems represented with less significance as a whole in the past literature reviews. The purpose of this paper is to have an intensive study to clarify the development of cost-based scheduling and sequencing (CSS) by reviewing the work published over several parameters for improving the understanding in this field. Various parameters, such as scheduling models, algorithms, industries, journals, publishers, publication year, authors, countries, constraints, objectives, uncertainties, computational time, and programming languages and optimization software packages are considered. In this research, the literature review of CSS is done for thirteen years (2010-2022). Although CSS research originated in manufacturing, it has been observed that CSS research publications also addressed case studies based on health, transportation, railway, airport, steel, textile, education, ship, petrochemical, inspection, and construction projects. A detailed evaluation of the literature is followed by significant information found in the study, literature analysis, gaps identification, constraints of work done, and opportunities in future research for the researchers and experts from the industries in CSS