PublicationsJournal Papers

The lack of a common executable modeling framework that integrates systems engineering, software design, and other engineering domains is a major impediment to seamless product development processes. Our research aims to overcome this system-software modeling gap by integrating computational, software-related, and model execution capabilities into OPM-based conceptual modeling, resulting in a holistic unified executable quantitative-qualitative modeling framework. The gap is overcome via a Methodical Approach to Executable Integrative Modeling—MAXIM, an extension of OPM ISO 19450:2015, a standardization approvement given on 2015. We present the principles of MAXIM and demonstrate its operation within OPCloud—a web-based collaborative conceptual OPM modeling framework. As a proof-of-concept, a model of an Airbus civil aircraft landing gear braking system is constructed and executed. Using MAXIM, engineers from five domains can collaborate at the very early phase of the system development and jointly construct a unified model that fuses qualitative and quantitative aspects of the various disciplines. This case study illustrates an important first step towards satisfying the critical and growing need to integrate systems engineering with software computations into a unified framework that enables a smooth transition from high-level architecting to detailed, discipline-oriented design. Such a framework is a key to agile yet robust future development of software-intensive systems.

As science and technology create an ecosystem that is becoming increasingly more knowledge-intensive, complex, and interconnected, the next generation science standards include systems thinking and systems modeling among 21^st skills that should be fostered. We examined the effect of an online cross-disciplinary learning process on the development of systems thinking and modeling skills among engineering students and engineering and science teachers. The study, which used quantitative and qualitative tools, included 55 participants who performed four food-related learning assignments and created conceptual models in Object-Process Methodology. Their responses to online assignments were analyzed along with their perceptions, captured via a reflection questionnaire. The online learning process in this study effectively enhanced the systems thinking and modeling skills of all learners, including those with no relevant background. One main conclusion that extends beyond online learning was that imparting the basics of systems thinking and conceptual modeling skills can be achieved even within a short period of time – less than one semester. The contribution of the study is the formation of theoretical and practical frameworks for the integration of cross-disciplinary model-based systems engineering online assignments into engineering and science curricula.

Objective: Pediatric Failure To Thrive (FTT), commonly presented in young infants, is often not diagnosed on time or missed. Lack of timely infants’ diagnosis can adversely affect their growth and development. We have developed and successfully tested FTTell—a model-based system for diagnosing FTT during common pediatric follow up.

Materials and Methods:  FTTell is an executable model-based diagnostic tool for assessing potential FTT during the postnatal stage. We use Object-Process Methodology extended with Methodical Approach to Executable Integrative Modeling, enabling qualitative considerations and quantitative parameters of the problem to be modeled jointly, enabling FTT diagnosis.

Results: The validity of FTTell is demonstrated on data collected from 100 infants. For each child, FTTell calculates a score that indicates FTT presence and severity. We compared the outcomes of the system to a pediatric gastroenterologist expert severity assessment. Of the 100 infants, the system initially diagnosed 82 as having FTT, which were diagnosed by the expert as well. Reassessment of the remaining infants yielded 87% efficacy.

Discussion: Pediatricians may miss infants with FTT, especially in borderline cases. FTTell can effectively serve as a FTT diagnosis tool, boosting pediatricians’ correct diagnosis and proper investigation. Our cloud-based system can be continuously updated with the latest research findings.

Conclusion: FTTell can diagnose FTT and its severity in infants with 87% accuracy. Pediatricians can use this model-based standardized approach to improve their FTT diagnosis and provide appropriate timely intervention when needed. Model-based diagnosis is a novel application of conceptual models, and OPM ISO 19450 is especially fit for this purpose. The model-based diagnosis approach can be extended beyond medicine to diagnosing problems with engineered, technological, and socio-technical systems.

As part of the design, development, and deployment of a massive open online course (MOOC) on model-based systems engineering, we introduced MORTIF—Modeling with Real-Time Informative Feedback, a new learning-by-doing feature that enables the learner to model, receive detailed feedback, and resubmit improved solutions. We examined the pedagogical usability of MORTIF by investigating characteristics of participants working with it, and their perceived contribution, preferred question type, and learning style. The research included 295 participants and applied the mixed-methods approach, using MOOC server data and online questionnaires. Analyzing 12,095 submissions, we found increasing frequency of using the model resubmitting option. Students ranked MORTIF as the highest of six question types in terms of preference and perceived contribution level. Nine learning style categories were identified and classified based on students’ verbal explanations regarding their preference of MORTIF over the other question types. MORTIF has been effective in promoting meaningful learning, supporting our hypothesis that the combination of active learning with real-time informative feedback is a learning mode that students eagerly embrace and benefit from. The benefits we identified for using MORTIF include active learning, provision of meaningful immediate feedback to the learner, the option to use the feedback on the spot and resubmitting an improved model, and its suitability for a variety of learning styles.

Modern systems comprise hardware and software components that together provide value through enabling the functionality that the system is intended to provide. Systems engineering (SE) and software engineering (SwE) are therefore interdependent, tightly coupled, and complementary activities that must be carefully aligned and coordinated throughout the system development process. Yet, these two disciplines have historically grown quite separated from each other, with too little interaction and mutual learning. In this work, we develop and evaluate Object-Process Programming (OPP) as a proof-of-concept for a common framework that integrates SE and SwE based on ISO 19450— Object-ProcessMethodology. The ability of designers to use the same paradigm for engineering the software, the hardware, and the system as a whole, using the same concepts and principles and the same design environment, described and discussed in this work, is a major step toward the integration and streamlining of engineering new systems that feature significant hardware and software components. To evaluate OPP, we established a focus group and conducted an experiment in which participants were asked to develop systems using OPP. Overall, the results were positive in terms of usability and understandability. In particular, the language and the environment were far superior in comparison to textual languages. OPP will contribute to the continuous endeavor to bridge the gap between SE and SwE by providing a seamless, easy-to-learn environment. Non-technical stakeholders can also benefit from OPP by improving their communication with technical stakeholders. The ideas under lying OPP have already served to augment OPM with computational capabilities.

Models have traditionally been mostly either prescriptive, expressing the function, structure and behavior of a system-to-be, or descriptive, specifying a system so it can be understood and analyzed. In this work, we offer a third kind—diagnostic models. We have built a model for assessing potential pediatric failure to thrive (FTT) during the perinatal stage. Although FTT is commonly found in young children and has been studied extensively, the exact etiology is often not clear. The ideal solution is for a pediatrician to input pertinent data and information in a single tool in order to obtain some assessment on the
potential etiology. We present FTTell—an executable model-based medical knowledge aggregation and diagnosis tool, in which the qualitative considerations and quantitative parameters of the problem are modeled using a Methodical Approach to Executable Integrative Modeling (MAXIM)—an extended version of Object-Process Methodology (OPM) ISO 19450, focusing on the perinatal stage. The efficacy of the tool is demonstrated on three real-life cases, and the tool’s diagnosis outcomes may be compared with and critiqued by a domain expert.