Temperature sensitive controller performance of MR dampers

Magnetorheological (MR) dampers can experience large temperature changes as a result of heating caused by energy dissipation, but control systems are often designed without consideration of this fact. Furthermore, due to the highly nonlinear behavior of MR dampers, many control strategies have been proposed and it is difficult to determine which is the most effective. This paper aims to address these issues through a numerical and experimental study of an MR mass isolator subject to temperature variation. A dynamic temperature dependant model of an MR damper is first developed and validated. Control system experiments are then performed using hardware-in-the-loopsimulations. Proportional, PID, gain scheduling, and on/off control strategies are found to be equally affected by temperature variation. Using simulations incorporating the temperature dependant MR damper model, it is shown that this is largely due to a change in fluid viscosity and the associated movement of the lower clipped optimal' control bound. This zero-volts condition determines how close any controller can perform to the ideal semiactive case, thus all types of controller are affected. In terms of relative performance, proportional and PID controllers perform equally well and outperform the on/off and gain scheduling strategies. Gain scheduling methods are superior to on/off control

Misunderstood or lacking legitimacy?

In spite of the rising interest in marketing within professional service firms in the last twenty years, past research has identified a reluctant acceptance and application of marketing within these organisations. The present paper will debate whether this is due to lack of understanding of the role of marketing, lack of acceptance as a valid management discipline suitable for professional services or lack of legitimacy as a profession in its own right. A brief overview of the role of marketing will be followed by a discussion on the professions, professional legitimacy and the professional organisation. Qualitative research was done in the form of in-depth interviews with marketing executives and accountancy and law professionals in fourteen firms across the UK. The research has revealed generational differences, misconceptions and outright conflict leading to resistance in the introduction and application of marketing, although the professionals have individually practiced a wide variety of marketing activities in their pursuit of gaining and maintaining clients. There has been a conspicuous resistance to the acceptance of marketing as a management tool within certain firms. The findings have opened up the spectre of inter-professional competition on legitimacy grounds

Taking the Punishment Out of the Process: From Substantive Criminal Justice Through Procedural Justice to Restorative Justice

If the punishment is taken out of the process, and the processes of criminal justice become effective at restoration--and if rigorous empirical research might show that a restorative process costs less money and produces greater public safety--that would be a result everyone would embrace

Contingency and Institutional Perspectives within the Liberal Professional Organisation

This developmental paper will argue the necessity of drawing on both the contingency and institutional theories when researching the professional organisation. It is based on a doctoral thesis that addresses the barriers to acceptance and application of marketing within accountancy and law firms. The paper briefly presents the relevant definitions of the professions and the role of the marketing function within the organisation. The Contingency approach and its relevance to theory building and research in marketing have been identified. Conversely, the Institutional approach has been identified as relevant to the professions. The two approaches are separately outlined and their theoretical foundations traced. Finally, two theoretical models are proposed for discussion. The theoretical model that has been further developed for the thesis explains the barriers to marketing as a result of organisational conflict between the need for response to contingency pressures and the internal and external institutional isomorphic pressures of maintaining professional legitimacy with the implications of forfeiting organisational efficiency

Femtosecond probing of bimolecular reactions: The collision complex

Progress has been made in probing the femtosecond dynamics of transition states of chemical reactions.(1) The "half-collision" case of unimolecular reactions has been experimentally investigated for a number of systems and much theoretical work has already been developed.(2) For bimolecular reactions, the case of full collision, the zero of time is a problem which makes the femtosecond temporal resolution of the dynamics a difficult task

Short-Chained Oligo(Ethylene Oxide)-Functionalized Gold Nanoparticles: Realization Of Significant Protein Resistance

Protein corona formed on nanomaterial surfaces play an important role in the bioavailability and cellular uptake of nanomaterials. Modification of surfaces with oligoethylene glycols (OEG) are a common way to improve the resistivity of nanomaterials to protein adsorption. Short-chain ethylene oxide (EO) oligomers have been shown to improve the protein resistance of planar Au surfaces. We describe the application of these EO oligomers for improved protein resistance of 30 nm spherical gold nanoparticles (AuNPs). Functionalized AuNPs were characterized using UV-Vis spectroscopy, dynamic light scattering (DLS), and zeta potential measurements. Capillary electrophoresis (CE) was used for separation and quantitation of AuNPs and AuNP-protein mixtures. Specifically, nonequilibrium capillary electrophoresis of equilibrium mixtures (NECEEM) was employed for the determination of equilibrium and rate constants for binding between citrate-stabilized AuNPs and two model proteins, lysozyme and fibrinogen. Semi-quantitative CE analysis was carried out for mixtures of EO-functionalized AuNPs and proteins, and results demonstrated a 2.5-fold to 10-fold increase in protein binding resistance to lysozyme depending on the AuNP surface functionalization and a 15-fold increase in protein binding resistance to fibrinogen for both EO oligomers examined in this study

Biaxial fatigue loading of notched composites

Thin walled, 2.54-cm (1-in.) diameter tubular specimens of T300/934 graphite/epoxy were fabricated and fatigue cycled in combinations of axial, torsional, and internal pressure loading. Two different four-ply layup configurations were tested: (0/90)S and (+ or - 45)S; all tubes contained a 0.48-cm (3/16-in.) diameter circular hole penetrating one wall midway along the tube length. S-N curves were developed to characterize fatigue behavior under pure axial, torsional, or internal pressure loading, as well as combined loading fatigue. A theory was developed based on the Hill plane stress model which enabled the S-N curve for combined stress states to be predicted from the S-N data for the uniaxial loading modes. Correlation of the theory with the experimental data proved to be remarkably good

Approximating the ground state of gapped quantum spin systems

We consider quantum spin systems defined on finite sets $V$ equipped with a metric. In typical examples, $V$ is a large, but finite subset of Z^d. For finite range Hamiltonians with uniformly bounded interaction terms and a unique, gapped ground state, we demonstrate a locality property of the corresponding ground state projector. In such systems, this ground state projector can be approximated by the product of observables with quantifiable supports. In fact, given any subset, X, of V the ground state projector can be approximated by the product of two projections, one supported on X and one supported on X^c, and a bounded observable supported on a boundary region in such a way that as the boundary region increases, the approximation becomes better. Such an approximation was useful in proving an area law in one dimension, and this result corresponds to a multi-dimensional analogue

The role of tool geometry in process damped milling

The complex interaction between machining structural systems and the cutting process results in machining instability, so called chatter. In some milling scenarios, process damping is a useful phenomenon that can be exploited to mitigate chatter and hence improve productivity. In the present study, experiments are performed to evaluate the performance of process damped milling considering different tool geometries (edge radius, rake and relief angles and variable helix/pitch). The results clearly indicate that variable helix/pitch angles most significantly increase process damping performance. Additionally, increased cutting edge radius moderately improves process damping performance, while rake and relief angles have a smaller and closely coupled effect