Multi-axial real-time hybrid simulation framework for testing nonlinear structure systems with multiple boundary interfaces

Hybrid simulation is a widely accepted laboratory testing approach that partitions a proposed structure into numerical and physical substructures, for a space- and cost-effective testing method. Structural elements that are expected to remain in the linear elastic range are usually modeled numerically, while computationally intractable nonlinear elements are tested physically. The loads and conditions at the boundaries between the numerical and physical substructures are imposed by servo-hydraulic actuators, with the responses measured by load cells and displacement transducers. Traditionally, these actuators impose boundary condition displacements at slow speeds, while damping and inertial components for the physical specimen are numerically calculated. This slow application of the boundary conditions neglects the rate-dependent behavior of the physical specimen. Real-time hybrid simulation (RTHS) is an alternative to slow speed hybrid simulation approach, where the responses of the numerical substructure are calculated and imposed on the physical substructure at real-world natural hazard excitation speeds. Damping, inertia, and rate-dependent material effects are incorporated in the physical substructure as a result of real-time testing. For a general substructure, the boundary interface has six degrees-of-freedom (DOF); therefore, an actuation system that can apply multi-axial loads is required. In these experiments, the boundary conditions at the interface between the physical and numerical substructures are imposed by two or more actuators. Significant dynamic coupling can be present between the actuators in such setups. Kinematic transformations are required for the operation of each actuator to achieve desired boundary conditions. Furthermore, each actuator possesses inherent dynamics that need appropriate compensation to ensure an accurate and stable operation. Most existing RTHS applications to date have involved the substructuring of the reference structures into numerical and physical components at a single interface with a one-DOF boundary condition and force imposed and measured. Multi-DOF boundary conditions have been explored in a few applications; however a general six-DOF stable implementation has never been achieved. A major research gap in the RTHS domain is the development of a multi-axial RTHS framework capable of handling six DOF boundary conditions and forces, as well as the presence of multiple physical specimens and numerical-to-physical interfaces. In this dissertation, a multi-axial real-time hybrid simulation (maRTHS) framework is developed for realistic nonlinear dynamic assessment of structures under natural hazard excitation. The framework is comprised of numerical and physical substructures, actuator-dynamics compensation, and kinematic transformations between Cartesian and actuator/transducer coordinates. The numerical substructure is compiled on a real-time embedded system, comprised of a microcontroller setup, with onboard memory and processing, that computes the response of finite element models of the structural system, which are then communicated with the hardware setup via the input-output peripherals. The physical substructure is composed of a multi-actuator boundary condition box, loadcells, displacement transducers, and one or more physical specimens. The proposed compensation is a model-based strategy based on the linearized identified models of individual actuators. The concepts of the model-based compensation approach are first validated in a shake table study, and then applied to single and multi-axis RTHS developments. The capabilities of the proposed maRTHS framework are demonstrated via the multi-axial load and boundary condition boxes (LBCBs) at the University of Illinois Urbana-Champaign, via two illustrative examples. First, the maRTHS algorithm including the decoupled controller, and kinematic transformation processes are validated. In this study, a moment frame structure is partitioned into numerical beam-column finite element model, and a physical column with an LBCB boundary condition. This experiment is comprised of six DOFs and excitation is only applied in the plane of the moment frame. Next, the maRTHS framework is subjected to a more sophisticated testing environment involving a multi-span curved bridge structure. In this second example, two LBCBs are utilized for testing of two physical piers, and excitation is applied bi-directionally. Results from the illustrative examples are verified against numerical simulations. The results demonstrate the accuracy and promising nature of the proposed state-of-the-art framework for maRTHS for nonlinear dynamic testing of structural systems using multiple boundary points

Multi-axial Real-time Hybrid Simulation Framework for Testing Nonlinear Structural Systems with Multiple Boundary Interfaces

Hybrid simulation is a widely accepted laboratory testing approach that partitions a proposed structure into numerical and physical substructures, for a space- and cost-effective testing method. Structural elements that are expected to remain in the linear elastic range are usually modeled numerically, while computationally intractable nonlinear elements are tested physically. The loads and conditions at the boundaries between the numerical and physical substructures are imposed by servo-hydraulic actuators, with the responses measured by loadcells and displacement transducers. Traditionally, these actuators impose boundary condition displacements at slow speeds, while damping and inertial components for the physical specimen are numerically calculated. This slow application of the boundary conditions neglects rate-dependent behavior of the physical specimen. Real-time hybrid simulation (RTHS) is an alternative to slow speed hybrid simulation approach, where the responses of numerical substructure are calculated and imposed on the physical substructure at real world natural hazard excitation speeds. Damping, inertia, and rate-dependent material effects are incorporated in the physical substructure as a result of real-time testing. For a general substructure, the boundary interface has six degrees-of-freedom (DOF); therefore, an actuation system that can apply multi-axial loads is required. In these experiments, the boundary conditions at the interface between the physical and numerical substructures are imposed by two or more actuators. Significant dynamic coupling can be present between the actuators in such setups. Kinematic transformations are required for operation of each actuator to achieve desired boundary conditions. Furthermore, each actuator possesses inherent dynamics that needs appropriate compensation to ensure an accurate and stable operation. Most existing RTHS applications to date have involved the substructuring of the reference structures into numerical and physical components at a single interface with a one-DOF boundary condition and force imposed and measured. Multi-DOF boundary conditions have been explored in a few applications, however a general six-DOF stable implementation has never been achieved. A major research gap in the RTHS domain is the development of a multi-axial RTHS framework capable of handling six DOF boundary conditions and forces, as well as presence of multiple physical specimens and numerical-to-physical interfaces. In this dissertation, a multi-axial real-time hybrid simulation (maRTHS) framework is developed for realistic nonlinear dynamic assessment of structures under natural hazard excitation. The framework is comprised of numerical and physical substructures, actuator-dynamics compensation, and kinematic transformations between Cartesian and actuator/transducer coordinates. The numerical substructure is compiled on a real-time embedded system, comprised of a microcontroller setup, with onboard memory and processing, that computes the response of finite element models of the structural system, which are then communicated with the hardware setup via the input-output peripherals. The physical substructure is composed of a multi-actuator boundary condition box, loadcells, displacement transducers, and one or more physical specimens. The proposed compensation is a model-based strategy based on the linearized identified models of individual actuators. The concepts of the model-based compensation approach are first validated in a shake table study, and then applied to single and multi-axis RTHS developments. The capabilities of the proposed maRTHS framework are demonstrated via the multi-axial load and boundary condition boxes (LBCBs) at the University of Illinois Urbana-Champaign, via two illustrative examples. First, the maRTHS algorithm including the decoupled controller, and kinematic transformation processes are validated. In this study, a moment frame structure is partitioned into numerical beam-column finite element model, and a physical column with an LBCB boundary condition. This experiment is comprised of six DOFs and excitation is only applied in the plane of the moment frame. Next, the maRTHS framework is subjected to a more sophisticated testing environment involving a multi-span curved bridge structure. In this second example, two LBCBs are utilized for testing of two physical piers, and excitation is applied bi-directionally. Results from the illustrative examples are verified against numerical simulations. The results demonstrate the accuracy and promising nature of the proposed state-of-the-art framework for maRTHS for nonlinear dynamic testing of structural systems using multiple boundary points.Ope

The influence of physical service recovery and online service recovery on trust and relationship retention

Service mishaps remain a profound topic in business due to their inevitability and detrimental impacts they bring about. As a result of this incessant detrimental effect, service recovery has been initiated into business exchanges to curb such. Moreover, service recovery programmes have been embarked on both in the offline and online delivery systems to retain this diverse need market consisting of the technological averse and experts in trading. This study therefore has to pinpoint the difficulties experienced in offline and online service recovery procedures and demarcate which of the two is the preferred channel. Service failures cut across all sectors and industries, and banking has not been spared in turn. Clients tend to choose a service recovery method based on various factors such as the panel of occurrence, technological skills and awareness, personal behaviours and available options provided by the service provider. Clients tend to choose a service recovery method based on various factors such as the panel of occurrence, technological skills and awareness, personal behaviours and available options provided by the service provider (Buttle, (2009); Clark & Melancon, (2013). The panel of occurrence depicts the method of service delivery that resulted in failed services, thus, an online service delivery is likely to attract an online resolution. Customers who transact online are highly likely to choose the same recovery method due to the associated innate benefits. Technological skills and awareness deal with the client’s articulateness in navigating the business’ website in effort to resolve the encountered problem. Personal behaviours explain that introvert clients would prefer to interact with the system and assistants online to resolve the issue while extroverts will choose the offline methods so as to experience facial interactions. Organisations sometimes detect the panel of solution based on the severity of the problem. Thus, for example, serious problems to be handled using physical means. Assessments of the degree of impact on retaining relations and gaining trust that presently employed recovery strategies pose were unearthed in this study. For physical service recovery, contact, empathy and politeness were assessed on the significance they have in recouping failed services. Responsiveness and the state of the bank’s websites will also depict the degree to which failed clients can be restored in online service delivery. Physical service recovery received greater apprehension by clients during a service error with empathy and politeness emerging as the most customer required successful strategy to enhance relations and trust thereafter. Despite its less preference, online service recovery strategies such as responsiveness and website interface resulted in significant correlations affirming their importance during service delivery and recovery. The measurement model fit quite well with sound goodness of fit indices results as per the comparison with the recommended thresholds. Moreover, the Structural Equation Model fit well with data collected

Design of Experiments

This book is a research publication that covers original research on developments within the Design of Experiments - Applications field of study. The book is a collection of reviewed scholarly contributions written by different authors and edited by Dr. Messias Borges Silva. Each scholarly contribution represents a chapter and each chapter is complete in itself but related to the major topics and objectives. The target audience comprises scholars and specialists in the field

Specialised Languages and Multimedia. Linguistic and Cross-cultural Issues

none2noThis book collects academic works focusing on scientific and technical discourse and on the ways in which this type of discourse appears in or is shaped by multimedia products. The originality of this book is to be seen in the variety of approaches used and of the specialised languages investigated in relation to multimodal and multimedia genres. Contributions will particularly focus on new multimodal or multimedia forms of specialised discourse (in institutional, academic, technical, scientific, social or popular settings), linguistic features of specialised discourse in multimodal or multimedia genres, the popularisation of specialised knowledge in multimodal or multimedia genres, the impact of multimodality and multimediality on the construction of scientific and technical discourse, the impact of multimodality/multimediality in the practice and teaching of language, the impact of multimodality/multimediality in the practice and teaching of translation, new multimedia modes of knowledge dissemination, the translation/adaptation of scientific discourse in multimedia products. This volume contributes to the theory and practice of multimodal studies and translation, with a specific focus on specialized discourse.Rivista di Classe A - Volume specialeopenManca E., Bianchi F.Manca, E.; Bianchi, F

Exploration of Atheism as a Diversity Issue and its Implications for Best Practice in Psychotherapy: Trajectories and Strengths

The conceptualization of Atheism has transformed considerably over the past century, making a transition from the taboo to a new movement of outspoken activism underlined by a strong self-identification with systemic nonbelief and sense of pride. Psychological literature has only begun to reflect the larger societal changes in perception and value over the past decade. As such, research has yet to adequately examine Atheism from a cultural perspective, creating an injustice in the psychotherapist’s ability to properly understand and treat patients in a comprehensive manner. Through the examination of trajectories leading to an Atheistic belief set, the application of a strength-based lens, and the dispelling of inaccurate, mythical thought, best practice can be applied in providing psychotherapuetic services to individuals who, at their core, do not believe in the existence of God(s)

The impact of task complexity on EFL learners' writing production across gender

The current study investigates the impact of task complexity on EFL learners' writing production across gender. Task complexity is the inherent cognitive demands of the tasks imposed on the learners by the structure of the tasks. It was investigated along the resource-dispersing variables of Pre-task planning time, post-task editing time and prior knowledge across the task difficulty variable of same gender. It also tries to intertwine the concepts of Task Complexity (i.e. TBLT) and sociolinguistics (i.e. gender issues). The aim of this study is to investigate the effectiveness of task complexity on gender differences of EFL learners' writing production which has been measured in terms of CAF i.e. complexity, accuracy and fluency. This can provide useful information in field of foreign language acquisition for language planners, curricula designers, and teachers. It is believed that it can contribute to improving EFL undergraduate students’ ability to a level of writing competence that is more likely to be satisfactory. The findings of the study suggest that variations of certain types of task complexity (in the design of pedagogic tasks) will have particular effects on attentional resources. Subsequently, the researcher believes that directing these attentional resources may have positive effects on learners’ language production and the ability to learn the target language. Besides, study concluded that there is statistically significant difference between males and females in terms of writing production along task complexity

Design and characterisation of a photonic sensor platform for the detection of biofilm formation

This thesis focuses on the development and characterisation of a waveguide-based photonic sensing platform for the detection of biofilm. This integrated photonic platform is based upon the high sensitivity of an optical field distribution formed in optical waveguides and the resulting changes in the refractive index and absorption of this environment. The sensor platform and materials formulations were established from simulation studies conducted with the Olympios software. These simulations demonstrated the importance of correctly specifying the material refractive index to achieve single-mode waveguides. They also highlighted the necessity to deposit a high refractive index layer (HRIL) on top of the optical waveguides in order to increase the intensity of the evanescent field responsible for the sensing performance of the platform. Platform fabrication exploited a low-cost process using photocurable organic-inorganic hybrid sol–gel materials, which were microstructured by UV-photolithography to form channel optical waveguides. A tantalum-based material was synthesized using the sol–gel process with refractive index as high as 1.87. This material was developed, optically characterised and applied as an evanescent field enhancement layer, deposited at the surface of the waveguide to increase the sensitivity of the sensing platform. The sensor characterisation was performed by monitoring the output intensity of the optical waveguide while contaminated water was monitored in both quasi-static and dynamic flow-rates on the platform. It is shown that the sensing performance of this biosensor platform relies on the applied flow-rate. In quasi-static flow rate, the biofilm formation was detected after 10 min of reactions, demonstrating the early stage biofilm formation in quasi-static flow-rate. The progressive increase of the flow-rate showed an increase of the detection time. Furthermore, the sensing performances of this photonic platform were found to be strongly dependent on the thickness of the HRIL, confirming the simulations studies. This work proved the concept of employing a waveguide-based photonic platform for the early detection of biofilm formation, including the induction phase, and as such, I believe this system has immense potential for future applications as a label-free and real-time biosensor platform for bioenvironmental applications

Local government policy in South Africa 1980-1989 (with specific reference to the Western Cape) : devolution, delegation, deconcentration or centralisation?

Bibliography: p. 512-557.This thesis is an examination of the National Party's policy of decentralisation of powers to local authorities in the 1980s. The thesis concentrates primarily on urban local government and its objectives are: 1. To trace the evolution of the south African state's policy of devolution of powers to local authorities in the 1980s; 2. To examine critically the main features of new local government legislation in this period, with particular reference to the devolution of powers policy; 3. To apply a normative framework for analysis, which can help serve as a heuristic device, in determining the extent of decentralisation that has occurred, to selected local authorities in the western Cape. The primary sources of research material that were consulted were Hansard, Acts of parliament, government commissions and gazettes, year books, provincial debates, ordinances, gazettes, circulars and local authorities' minutes and publications. Approximately 50 qualitative interviews were also conducted. The framework of analysis utilised certain indices, namely personnel, access, functions, party politics, finance and hierarchical relations, to measure the extent of decentralisation that has occurred in three local authorities in the Western Cape. This framework helped determine that limited devolution of powers had occurred. There were four major reasons for the reluctance of the National Party to devolve extensive powers to local authorities. First and foremost, reform policy was made in an elitist, top-down manner by a small group of reformers in order to ensure that the government could share power without losing control. The corollary of this centralised policy-making was the tendency of centr.al and provincial authorities not to devolve extensive powers to local authorities. Secondly, there was the viewpoint of the central government that the local government development process had to be controlled from the top because of the lack of sufficient skills, experience and finance at local level. Thirdly, the need for macro-economic financial control was· also a brake on the devolution process. Fourthly, the government believed that, in a unitary state, central government should always have a relative degree of control over local authorities' activities