A resilience measure to guide system design and management

This paper presents a measure of resilience which can guide system design and management. Systems design must incorporate resilience to provide stakeholders with the most appropriate solution for their life-cycle needs. Design of resilient systems demands a measure of the resilience afforded by a system proposal which can be used to compare design proposals. The measurement method should balance the interest in resilience with all other proposal evaluation criteria, and incorporate the effect of the sequence of unknown future events affecting the system. Ideally, the resilience measure should also be useful to guide management decisions re maintenance or upgrade during the system life. This paper presents a method to measure system resilience which can be applied to engineered systems in general, not just a specific class of systems, is threat type agnostic, and does not presuppose any ‘desirable’ outcome allowing a system specific determination of ‘desirable’ outcomes

Undergraduate students' engagement with systems thinking: results of a survey study

This paper describes the results obtained for the affective engagement of students with systems thinking. In prior work the authors have developed and validated a questionnaire instrument for measuring affective engagement of undergraduate engineering students with systems thinking. This paper presents results obtained when the questionnaire was used with undergraduate students. Two surveys with different versions of the questionnaire, one using positive grammar questions only and the other using a mix of positive and negative constructs, were used to measure the students’ engagement with systems thinking and its relationship with gender, age and work experience. Each questionnaire version was applied to a different sample, the first, 186 participants, completed the positive grammar version, and, the second group of 163 completed the mixed version. The results show that participants in both studies valued systems thinking in each of the three dimensions of the systems thinking construct. Statistical tests confirmed no significant gender differences in either study. Student engagement with the practical dimension of systems thinking was shown to vary, with statistical significance, with groups of age, years of work experience and country of the university

Systems thinking in systems engineering

Systems thinking (ST) offers a holistic approach rather than a reductionist approach, through appreciating all the interrelated dimensions of complex problems. It is important for understanding and interacting with all kinds of systems, in order to manage complex problems. However, the broad range of the ST‐related literature found in various disciplines, generates a great deal of disagreement about definitions and understanding of systems thinking. Despite the current ambiguities of ST definitions, its underlying philosophy has a long history. This paper aims to clarify what ST is in the modern day and why it is defined in so many different ways. It identifies a number of interpretations of systems thinking with the purpose of clarifying what it is and why it is variously understood. The main aims of this paper is to propose a new ST construct, and to define its role in the practice of Systems Engineering (SE). This paper then draws implications of the new ST construct for SE education

Measurement of resilience and the time value of resilience

In prior work, a measure of resilience for use in systems design and management was presented. The measure has the form of a time integral of the system performance level. This form generates the research question: Is the time value of resilience a meaningful concept, like the time value of money in engineering economics. This article presents four scenarios to explore the relationship between time and the value of resilience of a product or system. The scenarios are: perishable commodity packaging, the value of resilience rapidly diminishes after the contents’ expiry; a consumer durable product for use in an evolving environment and interface requirement, where the value of resilience is related to the expiry of platform resilience capability; a national infrastructure asset, where usage increases during the system life; and a factory, where the value of resilience depends on the obsolescence of the product. In the first two and last cases, the value of resilience is high for a finite interval and then low or zero. In the third, the value of resilience increases as the asset age

Chapter 14: The challenge of performing research which will contribute helpful engineering knowledge concerning emergence

This chapter discusses the nature of research which is required to provide knowledge of emergence that is useful to engineers in the conduct of engineering work. The discussion begins with three elements which form the foundation of the argument: the contrast of the purposes of engineering and science and the different perspectives of knowledge associated with those purposes; the diversity of views on “emergence” and an argument for working with one definition; and an outline of a framework for classifying the objectives of research activities associated with the kind of knowledge that is needed. These foundations are used to evaluate a number of approaches to research in engineering to assess the contribution that the research approaches make to discovery of matters associated with emergence. The research approaches considered are case studies, forensic investigations, post hoc and experimental studies, fundamental theoretical studies and contributions to the engineering task. These approaches instantiate different research purposes and therefore, naturally will be associated with different methods. The previous analysis is discussed in the context of the nature of research published in response to the imperatives presented to faculty by the career measures of success to explain the current emphasis on what is investigated and the limitations for engineering in that focus. In the final section an approach for addressing the issue of emergence in engineering is presented which leads to a brief statement of a desirable outcome of research into emergence conducted with a view to assisting the practice of engineering

A method to establish a trade-space of system requirements and life cycle cost

Systems engineering traditionally approaches design of systems through determination of requirements for and implementation of a system. The system is conceived as something to enable achievement of an effect with the tacit assumption that the system to be designed must achieve technical performance, including availability characteristics, which enable delivery of the whole of the intended effect. This approach determines the technical requirements of the system to ensure achievement of the system purpose under assumptions about how the system, or fleet, would be deployed to provide the intended service. Commonly cost is addressed after requirements, either to find the cheapest method to achieve the requirements or as one dimension of a trade-space analysis. We explore a different philosophy for finding the system requirements; starting with the required system level service provision, but agnostic about the technical quality needed. We investigate a trade-space including the life cycle cost (LCC) of service provision as a contribution to determining subsystem requirements. We model the life cycle, for many variations of technical composition, using a Monte Carlo method, and show that a trade-space of LCC and requirements is likely to produce a cheaper solution than starting with sub-system requirements

Development and initial validation of an instrument to measure students' learning about systems thinking: the affective domain

The purpose of this study was to develop and validate a new, theoretically-based scale that would assess students' learning about systems thinking in relation to the affective domain in systems engineering education. Students' learning of systems thinking in the affective domain deal with emotions, feelings and valuing the related cognitive systems thinking aspects. It is characterized by belief in the power of systems thinking to enable them to develop superior engineered products and systems. This paper describes the psychometric properties of the scale as the basis for future use with a target population of engineering students. It provides the results of an instrument test analysis of data collected from a representative set of the target audience of the instrument. The participants in this study were 180 undergraduate engineering students who enrolled in a systems engineering course. Exploratory factor analysis of the scale for the sample yielded factors largely consistent with conceptualization and construction of the subscales. Confirmatory factor analysis of the scale also supports the initial factor structure. The results suggest that this instrument may be useful to researchers and practitioners interested in measuring systems thinking in engineering students, particularly in the affective domain

Standard methods for Apis mellifera venom research

Honey bees have a sting which allows them to inject venomous substances into the body of an opponent or attacker. As the sting originates from a modified ovipositor, it only occurs in the female insect, and this is a defining feature of the bee species that belong to a subclade of the Hymenoptera called Aculeata. There is considerable interest in bee venom research, primarily because of an important subset of the human population who will develop a sometimes life threatening allergic response after a bee sting. However, the use of honey bee venom goes much further, with alleged healing properties in ancient therapies and recent research. The present paper aims to standardize selected methods for honey bee venom research. It covers different methods of venom collection, characterization and storage. Much attention was also addressed to the determination of the biological activity of the venom and its use in the context of biomedical research, more specifically venom allergy. Finally, the procedure for the assignment of new venom allergens has been presented. Las abejas meliferas tienen un aguijon que les permite inyectar sustancias venenosas en el cuerpo de un oponente o atacante. El aguijon es un ovipositor modificado que solo se manifiesta en el insecto hembra, siendo este una caracteristica que define a las especies de abejas que pertenecen al subclado de himenopteros llamada Aculeata. Hay un interes considerable en la investigacion del veneno de abeja, principalmente debido a que un porcentaje importante de la poblacion humana desarrollara una respuesta alergica - a veces mortal - a la picadura de abeja. Sin embargo, el uso del veneno de la abeja melifera abarca mucho mas, con presuntas propiedades curativas en terapias antiguas e investigaciones recientes. El presente trabajo tiene como objetivo estandarizar metodos seleccionados para la investigacion del veneno de las abejas meliferas. Cubre diferentes metodos de recoleccion, caracterizacion y almacenamiento de veneno. Tambien se presto mucha atencion a la determinacion de la actividad biologica del veneno y su uso en el contexto de la investigacion biomedica, mas especificamente la alergia al veneno. Finalmente, se ha presentado el procedimiento para la asignacion de nuevos alergenos de veneno

Incorporation of uranium into hematite during crystallization from ferrihydrite

Ferrihydrite was exposed to U(VI)-containing cement leachate (pH 10.5) and aged to induce crystallization of hematite. A combination of chemical extractions, TEM, and XAS techniques provided the first evidence that adsorbed U(VI) (≈3000 ppm) was incorporated into hematite during ferrihydrite aggregation and the early stages of crystallization, with continued uptake occurring during hematite ripening. Analysis of EXAFS and XANES data indicated that the U(VI) was incorporated into a distorted, octahedrally coordinated site replacing Fe(III). Fitting of the EXAFS showed the uranyl bonds lengthened from 1.81 to 1.87 Å, in contrast to previous studies that have suggested that the uranyl bond is lost altogether upon incorporation into hematite the results of this study both provide a new mechanistic understanding of uranium incorporation into hematite and define the nature of the bonding environment of uranium within the mineral structure. Immobilization of U(VI) by incorporation into hematite has clear and important implications for limiting uranium migration in natural and engineered environments. © 2014 American Chemical Society

Management of toxic ingestions with the use of renal replacement therapy

Although rare, renal replacement therapy (RRT) for the treatment of the metabolic, respiratory and hemodynamic complications of intoxications may be required. Understanding the natural clearance of the medications along with their volume of distribution, protein binding and molecular weight will help in understanding the benefit of commencing RRT. This information will aid in choosing the optimal forms of RRT in an urgent setting. Overdose of common pediatric medications are discussed with suggestions on the type of RRT within this educational review