Model updating using uncertain experimental modal data

The propagation of parameter uncertainty in structural dynamics has become a feasible method to determine the probabilistic description of the vibration response of industrial scale �nite element models. Though methods for uncertainty propagation have been developed extensively, the quanti�cation of parameter uncertainty has been neglected in the past. But a correct assumption for the parameter variability is essential for the estimation of the uncertain vibration response. This paper shows how to identify model parameter means and covariance matrix from uncertain experimental modal test data. The common gradient based approach from deterministic computational model updating was extended by an equation that accounts for the stochastic part. In detail an inverse approach for the identi�cation of statistical parametric properties will be presented which will be applied on a numerical model of a replica of the GARTEUR SM-AG19 benchmark structure. The uncertain eigenfrequencies and mode shapes have been determined in an extensive experimental modal test campaign where the aircraft structure was tested repeatedly while it was 130 times dis- and reassembled in between each experimental modal analysis

Organizational readiness for wellness promotion - a survey of 100 African American church leaders in South Los Angeles.

BackgroundChurches are an important asset and a trusted resource in the African American community. We needed a better understanding of their readiness to engage in health promotion before launching a large-scale health promotion effort in partnership with South Los Angeles churches.MethodsIn 2017, we conducted surveys with leaders of 100 churches. Surveys were conducted face-to-face (32%) or by telephone (68%) with senior pastors (one per church) and lasted on average 48 min. We compared small (less than 50 active members), medium (50-99 active members) and large churches (at least 100 active members), and assessed which church characteristics were associated with the implementation of wellness activities.ResultsMedium and large churches conducted significantly more wellness activities than small churches and were more likely to have wellness champions and health policies. Regardless of church size, insufficient budget was the most commonly cited barrier to implement wellness activities (85%). A substantial proportion of churches was not sure how to implement wellness activities (61%) and lacked volunteers (58%). Forty-five percent of the variation in the number of wellness activities in the last 12 months was explained by church characteristics, such as size of congregation, number of paid staff, leadership engagement, having a wellness ministry and barriers.ConclusionsMany churches in South Los Angeles are actively engaged in health promotion activities, despite a general lack of resources. We recommend a comprehensive assessment of church characteristics in intervention studies to enable the use of strategies (e.g., stratification by size) that reduce imbalances that could mask or magnify study outcomes. Our data provide empirical support for the inner settings construct of the Consolidated Framework for Implementation Research in the context of health promotion in African American churches

CFD and aeroelastic analysis of the MEXICO wind turbine

This paper presents an aerodynamic and aeroelastic analysis of the MEXICO wind turbine, using the compressible HMB solver of Liverpool. The aeroelasticity of the blade, as well as the effect of a low-Mach scheme were studied for the zero-yaw 15m/s wind case and steady- state computations. The wake developed behind the rotor was also extracted and compared with the experimental data, using the compressible solver and a low-Mach scheme. It was found that the loads were not sensitive to the Mach number effects, although the low-Mach scheme improved the wake predictions. The sensitivity of the results to the blade structural properties was also highlighted

Connecting Dream Networks Across Cultures

Many species dream, yet there remain many open research questions in the study of dreams. The symbolism of dreams and their interpretation is present in cultures throughout history. Analysis of online data sources for dream interpretation using network science leads to understanding symbolism in dreams and their associated meaning. In this study, we introduce dream interpretation networks for English, Chinese and Arabic that represent different cultures from various parts of the world. We analyze communities in these networks, finding that symbols within a community are semantically related. The central nodes in communities give insight about cultures and symbols in dreams. The community structure of different networks highlights cultural similarities and differences. Interconnections between different networks are also identified by translating symbols from different languages into English. Structural correlations across networks point out relationships between cultures. Similarities between network communities are also investigated by analysis of sentiment in symbol interpretations. We find that interpretations within a community tend to have similar sentiment. Furthermore, we cluster communities based on their sentiment, yielding three main categories of positive, negative, and neutral dream symbols.Comment: 6 pages, 3 figure

Shake table testing of a tuned mass damper inerter (Tmdi)-equipped structure and nonlinear dynamic modeling under harmonic excitations

This paper presents preliminary experimental results from a novel shaking table testing campaign investigating the dynamic response of a two-degree-of-freedom (2DOF) physical specimen with a grounded inerter under harmonic base excitation and contributes a nonlinear dynamic model capturing the behavior of the test specimen. The latter consists of a primary mass connected to the ground through a high damping rubber isolator (HDRI) and a secondary mass connected to the primary mass through a second HDRI. Further, a flywheel-based rack-and-pinion inerter prototype device is used to connect the secondary mass to the ground. The resulting specimen resembles the tuned mass damper inerter (TMDI) configuration with grounded inerter analytically defined and numerically assessed by the authors in a number of previous publications. Physical specimens with three different inerter coefficients are tested on the shake table under sine-sweep excitation with three different amplitudes. Experimental frequency response functions (FRFs) are derived manifesting a softening nonlinear behavior of the specimens and enhanced vibration suppression with increased inerter coefficient. Further, a 2DOF parametric nonlinear model of the specimen is established accounting for non-ideal inerter device behavior and its potential to characterize experimental response time-histories, FRFs, and force-displacement relationships of the HDRIs and of the inerter is verified

Constitutional Reasonableness

The concept of reasonableness pervades constitutional doctrine. The concept has long served to structure common law doctrines from negligence to criminal law, but its rise in constitutional law is more recent and diverse. This Article aims to unpack surprisingly different formulations of what the term reasonable means in constitutional doctrine, which actors it applies to, and how it is used. First, the underlying concept of reasonableness that courts adopt varies, with judges using competing objective, subjective, utility-based or custom-based standards. For some rights, courts incorporate more than one usage at the same time. Second, the objects of the reasonableness standard vary, assessed from the perspective of judges, officials, legislators, or citizens, and from the perspective of individual decision-makers or general institutional or government perspectives. Third, judges may variously apply a constitutional reasonableness standard to a right, to the assertion of defenses, waivers, or limitations on obtaining a remedy for the violation of a right, or to standards of review. The use of the common term reasonableness” to such different purposes can blur distinctions between each of these three categories of standards. The flexibility and malleability of reasonableness may account for its ubiquity and utility. Entire constitutional standards can - and have - shifted their meaning entirely as judges shift from one concept or usage of reasonableness while appearing not to change the “reasonableness” standard or to depart from precedent. That ambiguity across multiple dimensions explains both the attraction and the danger of constitutional reasonableness. In this Article, I point the way to an alternative: regulatory constitutional reasonableness, in which reasonableness is presumptively informed by objective and empirically-informed standards of care, rather than a set of shape-shifting inquiries

Disconnection of network hubs and cognitive impairment after traumatic brain injury.

Traumatic brain injury affects brain connectivity by producing traumatic axonal injury. This disrupts the function of large-scale networks that support cognition. The best way to describe this relationship is unclear, but one elegant approach is to view networks as graphs. Brain regions become nodes in the graph, and white matter tracts the connections. The overall effect of an injury can then be estimated by calculating graph metrics of network structure and function. Here we test which graph metrics best predict the presence of traumatic axonal injury, as well as which are most highly associated with cognitive impairment. A comprehensive range of graph metrics was calculated from structural connectivity measures for 52 patients with traumatic brain injury, 21 of whom had microbleed evidence of traumatic axonal injury, and 25 age-matched controls. White matter connections between 165 grey matter brain regions were defined using tractography, and structural connectivity matrices calculated from skeletonized diffusion tensor imaging data. This technique estimates injury at the centre of tract, but is insensitive to damage at tract edges. Graph metrics were calculated from the resulting connectivity matrices and machine-learning techniques used to select the metrics that best predicted the presence of traumatic brain injury. In addition, we used regularization and variable selection via the elastic net to predict patient behaviour on tests of information processing speed, executive function and associative memory. Support vector machines trained with graph metrics of white matter connectivity matrices from the microbleed group were able to identify patients with a history of traumatic brain injury with 93.4% accuracy, a result robust to different ways of sampling the data. Graph metrics were significantly associated with cognitive performance: information processing speed (R(2) = 0.64), executive function (R(2) = 0.56) and associative memory (R(2) = 0.25). These results were then replicated in a separate group of patients without microbleeds. The most influential graph metrics were betweenness centrality and eigenvector centrality, which provide measures of the extent to which a given brain region connects other regions in the network. Reductions in betweenness centrality and eigenvector centrality were particularly evident within hub regions including the cingulate cortex and caudate. Our results demonstrate that betweenness centrality and eigenvector centrality are reduced within network hubs, due to the impact of traumatic axonal injury on network connections. The dominance of betweenness centrality and eigenvector centrality suggests that cognitive impairment after traumatic brain injury results from the disconnection of network hubs by traumatic axonal injury