An Approach to Systems-of-Systems Structural Analysis through Interoperability Assessment: Application on Moroccan Case

In this paper, we propose an indicator to systems-of-systems (SoS) structural analysis through dependencies evaluation which is based on interoperability and exchange inefficiency assessments, with dependencies representing links between component systems within the SoS. Interoperability is a quality that can be viewed from various perspectives. Therefore, we propose an illustrative classification for interoperability that embraces: barriers, scopes and levels. Our study involves a set of metrics to assess each interdependency’s interoperability barriers within the SoS through interoperability levels. Two different case studies, from the Moroccan economic infrastructure, are presented to apply the proposed approach. Results are cross-compared and evaluated.

A Four-Stage Framework for the Identification of Information Flow Inefficiencies in the Manufacturing Environment

A four-stage methodological framework useful to analyze the performance of a product development process, with a focus on the information flow inefficiencies is presented. The formal and informal communication exchange between interacting tasks is captured through the Dependency Structure Matrix (DSM) representation, while the properties of the information flow structure are explored calculating metrics of Social Network Analysis (SNA). Information exchange inefficiency of process tasks is calculated performing Data Envelopment Analysis (DEA).

Effect of a patent foramen ovale on pulmonary gas exchange efficiency at rest and during exercise

The prevalence of a patent foramen ovale (PFO) is ∼30%, and this source of right-to-left shunt could result in greater pulmonary gas exchange impairment at rest and during exercise. The aim of this work was to determine if individuals with an asymptomatic PFO (PFO+) have greater pulmonary gas exchange inefficiency at rest and during exercise than subjects without a PFO (PFO−). Separated by 1 h of rest, 8 PFO+ and 8 PFO− subjects performed two incremental cycle ergometer exercise tests to voluntary exhaustion while breathing either room air or hypoxic gas [fraction of inspired O2 (FiO2) = 0.12]. Using echocardiography, we detected small, intermittent boluses of saline contrast bubbles entering directly into the left atrium within 3 heart beats at rest and during both exercise conditions in PFO+. These findings suggest a qualitatively small intracardiac shunt at rest and during exercise in PFO+. The alveolar-to-arterial oxygen difference (AaDo2) was significantly ( P < 0.05) different between PFO+ and PFO− in normoxia (5.9 ± 5.1 vs. 0.5 ± 3.5 mmHg) and hypoxia (10.1 ± 5.9 vs. 4.1 ± 3.1 mmHg) at rest, but not during exercise. However, arterial oxygen saturation was significantly different between PFO+ and PFO− at peak exercise in normoxia (94.3 ± 0.9 vs. 95.8 ± 1.0%) as a result of a significant difference in esophageal temperature (38.4 ± 0.3 vs. 38.0 ± 0.3°C). An asymptomatic PFO contributes to pulmonary gas exchange inefficiency at rest but not during exercise in healthy humans and therefore does not explain intersubject variability in the AaDo2 at maximal exercise.

Pulmonary characteristics in COPD and mechanisms of increased work of breathing

Mechanical characteristics and gas exchange inefficiencies of the lungs contribute to increased work of ventilation in chronic obstructive pulmonary disease (COPD) at rest and exercise, and the energy cost of ventilation is increased in COPD at any external work level. Assuming typical ventilatory variables and respiratory characteristics, we estimated the relative contributions of inspiratory and expiratory resistance, dynamic elastance, intrinsic positive end-expiratory pressure, and gas exchange inefficiency to the work of breathing, finding that the last of these is likely to be of major importance. Dynamic hyperinflation can be seen as both an impediment to inspiratory muscle function and an essential component of adaptation to severe obstruction. Extrinsic restriction, in which the chest wall fails to achieve and maintain abnormally high lung volumes in COPD, can limit ventilatory function and contribute to disability.

The Lungs During Exercise

Lung function in humans during exercise has usually been regarded as well maintained, or even improved, compared with rest. Recent data, however, document considerable gas exchange inefficiency during very heavy work by well-trained normal subjects, and even more so when world-class athletes exercise maximally. Ascent to altitude clearly accentuates these problems. The deterioration of gas exchange seems to be caused mostly by failure of equilibration by diffusion of oxygen between alveolar gas and end-capillary blood.