Staggered solution procedures for multibody dynamics simulation

The numerical solution procedure for multibody dynamics (MBD) systems is termed a staggered MBD solution procedure that solves the generalized coordinates in a separate module from that for the constraint force. This requires a reformulation of the constraint conditions so that the constraint forces can also be integrated in time. A major advantage of such a partitioned solution procedure is that additional analysis capabilities such as active controller and design optimization modules can be easily interfaced without embedding them into a monolithic program. After introducing the basic equations of motion for MBD system in the second section, Section 3 briefly reviews some constraint handling techniques and introduces the staggered stabilized technique for the solution of the constraint forces as independent variables. The numerical direct time integration of the equations of motion is described in Section 4. As accurate damping treatment is important for the dynamics of space structures, we have employed the central difference method and the mid-point form of the trapezoidal rule since they engender no numerical damping. This is in contrast to the current practice in dynamic simulations of ground vehicles by employing a set of backward difference formulas. First, the equations of motion are partitioned according to the translational and the rotational coordinates. This sets the stage for an efficient treatment of the rotational motions via the singularity-free Euler parameters. The resulting partitioned equations of motion are then integrated via a two-stage explicit stabilized algorithm for updating both the translational coordinates and angular velocities. Once the angular velocities are obtained, the angular orientations are updated via the mid-point implicit formula employing the Euler parameters. When the two algorithms, namely, the two-stage explicit algorithm for the generalized coordinates and the implicit staggered procedure for the constraint Lagrange multipliers, are brought together in a staggered manner, they constitute a staggered explicit-implicit procedure which is summarized in Section 5. Section 6 presents some example problems and discussions concerning several salient features of the staggered MBD solution procedure are offered in Section 7

A computational procedure for multibody systems including flexible beam dynamics

A computational procedure suitable for the solution of equations of motions for flexible multibody systems has been developed. The flexible beams are modeled using a fully nonlinear theory which accounts for both finite rotations and large deformations. The present formulation incorporates physical measures of conjugate Cauchy stress and covariant strain increments. As a consequence, the beam model can easily be interfaced with real-time strain measurements and feedback control systems. A distinct feature of the present work is the computational preservation of total energy for undamped systems; this is obtained via an objective strain increment/stress update procedure combined with an energy-conserving time integration algorithm which contains an accurate update of angular orientations. The procedure is demonstrated via several example problems

Computational methods and software systems for dynamics and control of large space structures

The deployment, assembly and mission-oriented maneuvering of space structures in orbit will trigger large motions of flexible, truss-type structures. In addition, the presence of on-board controls both for attitude stabilization and specified vibration tolerance requirements may further complicate the dynamic behavior of the orbiting structures. Because of safety and cost considerations, the dynamic response of the combined structural and control systems must be predicted reliably. This need can only be met through the development of reliable and efficient simulation capabilities, since there is general agreement that on-orbit experiments should be limited because of cost, time and facility constraints. The long-term objective of this research effort is to develop a next-generation computer simulator for the dynamics and control of large space structures. The simulator will be based on integrating four research thrusts: a new multibody dynamics formulation methodology, modeling capabilities in long/slender truss-beam components with realistic joints, efficient computational procedures that can be implemented either in sequential or concurrent computers, and prototype simulation modules that can be easily processed into a modern large-scale engineering software system such as the NASA/Computational Structural Mechanics (CSM) testbed

Using arts‐based methods to develop service user led learning materials for social work education

Theories transmitted to students about professional practice in health and social care come traditionally from the perspective of practitioners, often as a heroic narrative, inevitably casting the service‐user in a passive role (Wiltshire, 2006). Post‐modern theorists like Foucault (1973) call this the authoritative 'gaze' that objectifies the user of public services, generating a power relationship between the professional and the service user. New perspectives are needed to redress this imbalance, drawing on the narratives of the service‐users themselves (Greenhalgh, 2006). Since 2007, a project led by service‐users at London South Bank University has been experimenting with new approaches to developing learning and teaching materials for social work education using opportunities afforded by the recent accreditation of awards within the General Social Care Council’s new Post Qualifying Framework. This paper outlines some of our experiences to date of experimenting with creative arts‐based approaches to facilitate the development of learning materials as ‘inherently creative acts’ (Sagan, 2007). This paper documents the experiences of a small group of service users and academics as we have all worked in different ways to co‐produce it using different mediums and media in order to contribute our views

Development and validation of the Australian Midwifery Standards Assessment Tool (AMSAT) to the Australian Midwife Standards for Practice 2018

© 2019 Australian College of Midwives Background: The Australian Midwifery Standards Assessment Tool (AMSAT) was developed against the Competency Standards for the Midwife in 2017 to enable consistent assessment of midwifery student performance in practice-based settings. The AMSAT requires revision and re-validation as the competency standards have now been superseded by the Midwife Standards for Practice 2018. Objective: This research revised and validated the AMSAT to assess performance of midwifery students against the Midwife Standards for Practice 2018 and assessed its sensitivity. Design: A mixed-methods approach was used in a two-phase process. Phase one involved the re-wording of the AMSAT and behavioural cue statements in an iterative participatory process with midwifery academics, assessors and students. The tool was field-tested in different assessment environments in phase two. Completed assessment forms were statistically analyzed, whilst assessor surveys were analysed using descriptive statistics and qualitative content analysis. Findings: Analysis of AMSAT (n = 255) indicates the tool as: internally reliable (Cronbach alpha >.9); valid (eigenvalue of 16.6 explaining 67% of variance); and sensitive (score analysis indicating increased levels of proficiency with progressive student experience). Analysis of surveys (n = 108) found acceptance of the tool for the purpose of summative and formative assessment, and in the provision of feedback to midwifery students on their performance. Conclusion: This study demonstrates that the re-developed AMSAT is a valid, reliable and acceptable tool to assess midwifery students’ performance against the Australian Midwife Standards for Practice This user-friendly tool can be used to standardize midwifery student assessment in Australia and enable continued benchmarking across education programs

An Exploration of Community Palliative Care Clinical Nurse Specialists Experiences of Working as Independent Prescribers: Part 2

The Department of Health has recently reiterated its commitment to the improvement in the quality of end of life care and emphasized the importance of all patients having rapid access to medication. The aim of this study was to explore the lived experiences of clinical nurse specialists who are able to prescribe independently in their role in providing support for patients with palliative care needs within the community setting. Interpretive phenomenology was employed in order to understand and interpret the experiences of six nurse independent prescribes employed as community palliative care clinical nurse specialists. This purposive sampling was preferred with semi-structured interviews as the most appropriate data collection technique. Participants interviewed reported that being able to prescribe enabled them to provide seamless, holistic care which facilitated faster access to medicines for their patients. This was particularly apparent at weekends when the patient's usual general practitioner (GP) was unavailable. Several benefits of nurse independent prescribing were also highlighted. However, the main barrier identified by most participants was the difficulty in accessing the patient's records. The overwhelming conclusion was that independent prescribing by community nurse specialists is beneficial for patients in the palliative care phase of their life and those deemed important to them as they are being cared for at home. Such benefits can also impact on other aspects of the patient's life including prompt availability of medicines, effective symptom control and consequently, an improved or enhanced quality of life for the patients and job satisfaction for the prescribing specialists nurses

Sum Rules for Multi-Photon Spectroscopy of Ions in Finite Symmetry

Models describing one- and two-photon transitions for ions in crystalline environments are unified and extended to the case of parity-allowed and parity- forbidden p-photon transitions. The number of independent parameters for characterizing the polarization dependence is shown to depend on an ensemble of properties and rules which combine symmetry considerations and physical models.Comment: 16 pages, Tex fil