What distinguishes a model of systems engineering from other models of designing? An ontological, data-driven analysis

This paper investigates how the core technical processes of the INCOSE model of systems engineering differ from other models of designing used in the domains of mechanical engineering, software engineering and service design. The study is based on fine-grained datasets produced using mappings of the different models onto the function-behaviour-structure (FBS) ontology. By representing every model uniformly, the same statistical analyses can be carried out independently of the domain of the model. Results of correspondence analysis, cumulative occurrence analysis and Markov model analysis show that the INCOSE model differs from the other models in its increased emphasis on requirements and on behaviours derived from structure, in the uniqueness of its verification and validation phases, and in some patterns related to the temporal development and frequency distributions of FBS design issues.

Investigation of Numerical Conditions of Moving Particle Semi-implicit for Two-Dimensional Wedge Slamming

The sensitivity of moving particle semi-implicit (MPS) simulations to numerical parameters is investigated in this study. Although the verification and validation (V&V) are important to ensure accurate numerical results, the MPS has poor performance in convergences with a time step size. Therefore, users of the MPS need to tune numerical parameters to fit results into benchmarks. However, such tuning parameters are not always valid for other simulations. We propose a practical numerical condition for the MPS simulation of a two-dimensional wedge slamming problem (i.e., an MPS-slamming condition). The MPS-slamming condition is represented by an MPS-slamming number, which provides the optimum time step size once the MPS-slamming number, slamming velocity, deadrise angle of the wedge, and particle size are decided. The simulation study shows that the MPS results can be characterized by the proposed MPS-slamming condition, and the use of the same MPS-slamming number provides a similar flow.

Assessing the Capability of Computational Fluid Dynamics Models in Replicating Wind Tunnel Test Results for the Rose Fitzgerald Kennedy Bridge

Despite its wide acceptance in various industries, CFD is considered a secondary option to wind tunnel tests in bridge engineering due to a lack of confidence. To increase confidence and to advance the quality of simulations in bridge aerodynamic studies, this study performed three-dimensional RANS simulations and DESs to assess the bridge deck aerodynamics of the Rose Fitzgerald Kennedy Bridge and demonstrated detailed procedures of the verification and validation of the applied CFD model. The CFD simulations were developed in OpenFOAM, the results of which are compared to prior wind tunnel test results, where general agreements were achieved though differences were also found and analyzed. The CFD model was also applied to study the effect of fascia beams and handrails on the bridge deck aerodynamics, which were neglected in most research to-date. These secondary structures were found to increase drag coefficients and reduce lift and moment coefficients by up to 32%, 94.3%, and 52.2%, respectively, which emphasized the necessity of including these structures in evaluations of the aerodynamic performance of bridges in service. Details of the verification and validation in this study illustrate that CFD simulations can determine close results compared to wind tunnel tests.

Fitting Assistive Technology for People with Hearing Loss: The Importance of Remote Microphone Systems′ Electroacoustic Verification

The remote microphone system (RMS) must be appropriately working when fitting it in a person with hearing loss. For this verification process, the concept of transparency is adopted. If it is not transparent, the hearing aid (HA) may not capture the user’s voice and his peers appropriately, or the RMS may not have the advantage in gain needed to emphasize the speaker’s voice. This study investigates the influence of the receiver’s gain setting on the transparency of different brands and models of RMS and HAs. It is a retrospective chart review with 277 RMS from three distinct brands (RMA, RMB, and RMC) and HAs. There was an association of the receiver’s gain setting with the variables: brand of the transmitter/receiver (p = 0.005), neck loop’s receiver vs. universal and dedicated receivers (p = 0.022), and between brands of HA and transmitter/receiver (p < 0.001). RMS transmitter (odds ratio [OR = 7.9]) and the type of receiver (neckloop [OR = 3.4]; universal [OR = 0.78]) presented a higher risk of not achieving transparency in default gain, confirming and extolling the need to include electroacoustic verification in the protocol of fitting, verification, and validation of RMS and HA.