Aircraft Cost Modelling using the Genetic Causal Technique within a Systems Engineering Approach

The paper is primarily concerned with the modelling of aircraft manufacturing cost. The aim is to establish an integrated life cycle balanced design process through a systems engineering approach to interdisciplinary analysis and control. The cost modelling is achieved using the genetic causal approach that enforces product family categorisation and the subsequent generation of causal relationships between deterministic cost components and their design source. This utilises causal parametric cost drivers and the definition of the physical architecture from the Work Breakdown Structure (WBS) to identify product families. The paper presents applications to the overall aircraft design with a particular focus on the fuselage as a subsystem of the aircraft, including fuselage panels and localised detail, as well as engine nacelles. The higher level application to aircraft requirements and functional analysis is investigated and verified relative to life cycle design issues for the relationship between acquisition cost and Direct Operational Cost (DOC), for a range of both metal and composite subsystems. Maintenance is considered in some detail as an important contributor to DOC and life cycle cost. The lower level application to aircraft physical architecture is investigated and verified for the WBS of an engine nacelle, including a sequential build stage investigation of the materials, fabrication and assembly costs. The studies are then extended by investigating the acquisition cost of aircraft fuselages, including the recurring unit cost and the non-recurring design cost of the airframe sub-system. The systems costing methodology is facilitated by the genetic causal cost modeling technique as the latter is highly generic, interdisciplinary, flexible, multilevel and recursive in nature, and can be applied at the various analysis levels required of systems engineering. Therefore, the main contribution of paper is a methodology for applying systems engineering costing, supported by the genetic causal cost modeling approach, whether at a requirements, functional or physical level.

Application of Heuristic Evaluation Method by Universal Design Experts

This study highlights how heuristic evaluation as a usability evaluation method can feed into current building design practice to conform to universal design principles. It provides a definition of universal usability that is applicable to an architectural design context. It takes the seven universal design principles as a set of heuristics and applies an iterative sequence of heuristic evaluation in a shopping mall, aiming to achieve a cost-effective evaluation process. The evaluation was composed of three consecutive sessions. First, five evaluators from different professions were interviewed regarding the construction drawings in terms of universal design principles. Then, each evaluator was asked to perform the predefined task scenarios. In subsequent interviews, the evaluators were asked to re-analyze the construction drawings. The results showed that heuristic evaluation could successfully integrate universal usability into current building design practice in two ways: (i) it promoted an iterative evaluation process combined with multi-sessions rather than relying on one evaluator and on one evaluation session to find the maximum number of usability problems, and (ii) it highlighted the necessity of an interdisciplinary ad hoc committee regarding the heuristic abilities of each profession. A multi-session and interdisciplinary heuristic evaluation method can save both the project budget and the required time, while ensuring a reduced error rate for the universal usage of the built environments.

The impact of adversity in childhood on outcomes in adulthood: research lessons and limitations

Summary: Current UK Government policy is concerned with the possible connections between childhood adversity, social exclusion and negative outcomes in adulthood. Understanding the impact of adverse childhood experiences on outcomes in adulthood is therefore key to informing effective policy and practice. In this article, the research on the impact of childhood adversity on outcomes in adulthood is reviewed in the broad categories of: mental health and social functioning; physical health; offending; service use; and economic impact. The literature on resilience that focuses on those who experience adversity, but do not have associated negative outcomes is also briefly considered. The strengths and limitations of the range of research methods used are then examined. Findings: Previous studies have tended to focus on specific forms of adversity, predominantly abuse and neglect, and either: specific populations and specific outcomes; specific populations and general outcomes; or general populations and specific outcomes. This means there may be incomplete understanding of the inputs (the range of adverse experiences in childhood), the processes (how these may affect people) and the outcomes (across domains in adulthood). Applications: It is concluded that it is important for social work researchers to engage in the current debate about how to prevent harmful childhood adversity and there is an important gap in the research for more interdisciplinary large-scale general population studies that consider the full range of childhood adversity and associated impacts across time and the possible processes involved.

Integrating situational and dispositional determinants of job satisfaction: Findings from three samples of professionals

Job satisfaction can be conceptualized as a function of situational conditions, personal characteristics, and interactions between both groups of variables. The authors compared the relative predictive power of these determinants in 3 samples of professionals (total N = 1,065). Perceived job characteristics (qualification possibilities, social support, stress, autonomy, participatory leadership) uniquely explained 7-22% of the variance in job satisfaction, and dispositional factors (Big Five, occupational self-efficacy, work centrality, mastery goals) uniquely explained 8-12% of the variance. Dispositional influences were partially mediated by perceived job characteristics. Interactions between situational and dispositional factors were of little significance. The authors concluded that perceived job characteristics (especially autonomy and participatory leadership) are important determinants of job satisfaction, and neuroticism is an important determinant as well. Highly educated professionals job satisfaction also seems to be driven by qualification possibilities.