Structural dynamics analyses testing and correlation

This report examines some aspects of the lack of close correlation between the predictions of analytical modeling of dynamic structures and the results of vibration tests on such structures, and suggests ways in which the correlation may be improved

The dynamic finite element model calibration method of concrete dams based on strong-motion records and multivariate relevant vector machines

In this work, a new finite element (FE) model calibration method of concrete dams based on strong-motion records and multivariate relevant vector machines (MRVM) is proposed. The modal features of a dam are extracted using second order blind identification (SOBI) based method at first. For some selected combinations of uncertain parameters of the FE model using the Latin hypercube design, the corresponding structural modal features are calculated using the finite element method (FEM). With these data, a procedure to calibrate the uncertain parameters of a dam’s dynamic FE model is developed. By taking the uncertain parameters as inputs and the calculated structural modal features using FEM as outputs, the MRVM model is trained to record the complex relationship between them. Then, the genetic algorithm (GA) is adopted to solve the optimization problem corresponding to the dynamic FE model calibration problem, and the trained MRVM model, instead of FEM, is used to obtain the modal parameters of a dam for different feasible solutions during the optimization search process to improve the computational efficiency. Using the simulated seismic response records of a numerical example the accuracy, robustness and computation efficiency of the proposed dynamic FE model calibration method is verified. The analysis result using the strong-motion records of a realistic concrete dam indicates that the proposed dynamic FE model calibration method has good performance

FRET-based dynamic structural biology: Challenges, perspectives and an appeal for open-science practices

Single-molecule FRET (smFRET) has become a mainstream technique for studying biomolecular structural dynamics. The rapid and wide adoption of smFRET experiments by an ever-increasing number of groups has generated significant progress in sample preparation, measurement procedures, data analysis, algorithms and documentation. Several labs that employ smFRET approaches have joined forces to inform the smFRET community about streamlining how to perform experiments and analyze results for obtaining quantitative information on biomolecular structure and dynamics. The recent efforts include blind tests to assess the accuracy and the precision of smFRET experiments among different labs using various procedures. These multi-lab studies have led to the development of smFRET procedures and documentation, which are important when submitting entries into the archiving system for integrative structure models, PDB-Dev. This position paper describes the current ‘state of the art’ from different perspectives, points to unresolved methodological issues for quantitative structural studies, provides a set of ‘soft recommendations’ about which an emerging consensus exists, and lists openly available resources for newcomers and seasoned practitioners. To make further progress, we strongly encourage ‘open science’ practices

Toward Accessible Multilevel Modeling in Systems Biology: A Rule-based Language Concept

Promoted by advanced experimental techniques for obtaining high-quality data and the steadily accumulating knowledge about the complexity of life, modeling biological systems at multiple interrelated levels of organization attracts more and more attention recently. Current approaches for modeling multilevel systems typically lack an accessible formal modeling language or have major limitations with respect to expressiveness. The aim of this thesis is to provide a comprehensive discussion on associated problems and needs and to propose a concrete solution addressing them

Experimental and numerical investigation of the influence of cables on utility pole modal property extraction

This work is a preliminary study on the dynamic response of poles with and without the influence of electrical lines. It is part of a research collaboration between NL Hydro and Memorial University of Newfoundland to achieve a better method of diagnosing aging wooden poles through non-destructive techniques. Previous researchers in this collaboration have found a good correlation between modal testing and wooden pole decay when the poles were tested in the laboratory. However, this correlation weakens with results from field tests, possible due to foundation or attached cables. Therefore, the main objectives of this research are to create a dynamic model for a pole and cable, to design an experimental rig of a reduced scale pole and cable, to use the experimental rig to validate those models, and to gain insights on the influences of the cable on the pole response for future research. The pole model consists of a Euler-Bernoulli cantilever beam obtained through the separation of variables method. The cable was modeled by using a lumped segmentation technique that considers the system as a sum of several lumped elements containing mass, ideal springs and viscous dampers. Both models are implemented using the commercial software 20sim, which is a graphical solver for the bond graph formalism that simplifies the process of building, assembling and testing the models. These models are intended to be preliminary tools for future work with trustable simulations, thus will allow for the study of the interaction between systems, the scaling of long transmission lines and their effects on the results of modal testing, and the insertion of other electric components and attachments usually found holding the cables on the poles (i.e. isolators, cross arms, ground wire, guy wires, etc.). A reduced physical model for the pole and cable is designed to proceed with the validation of the developed models. Modal testing and time series measurements are performed over the apparatus and compared with the simulation results, showing good comparative results. In addition, the methods developed, physical and computational, can be used in the continuation of this work

A framework to improve the architecture quality of software intensive systems

Over the past decade, the amount and complexity of software for almost any business sector has increased substantially. Unfortunately, the increased complexity of software in the systems to be built has often lead to a significant mismatch between the planned and the implemented products. One common problem is that system-wide quality attributes such as safety, reliability, performance, and modifiability are not sufficiently considered in software architecture design. Typically, they are addressed in an ad-hoc and unstructured fashion. Since rationales for architectural decisions are frequently missing, risks associated with those decisions can be neither identified, nor mitigated in a systematic way. Consequently, there is a high probability that the resulting software architecture fails to meet business goals and does not allow the building of an adequate system. This work presents QUADRAD, a framework for Quality-Driven Architecture Development. QUADRAD is capable of improving architecture quality for software-intensive systems in a systematic way. It supports the development of architectures that are optimized according to their essential quality requirements. Such architectures permit the building of systems that are better aligned to the principal market needs and business goals. QUADRAD is complemented by the Architecture Exploration Tool (AET), which supports architecture evaluations and helps in documenting the fundamental design decisions of an architecture. QUADRAD has been validated in three industrial projects. For each of these projects the architecture quality could be significantly increased. The results confirm the hypothesis of this work and demonstrate how critical problems in the transition from requirements to architecture design can be mitigated