Conversion of the hot torsion test results into flow curve with multiple regimes of hardening

The method of Fields and Backofen has been commonly used to reduce the data obtained by hot torsion test into flow curves. The method, however, is most suitable for materials with monotonic strain hardening behaviour. Other methods such as Stüwe’s method, tubular specimens, differential testing and the inverse method, each suffer from similar drawbacks. It is shown in the current work that for materials with multiple regimes of hardening any method based on an assumption of constant hardening indices introduces some errors into the flow curve obtained from the hot torsion test. Therefore such methods do not enable accurate prediction of onset of recrystallisation where slow softening occurs. A new method to convert results from the hot torsion test into flow curves by taking into account the variation of constitutive parameters during deformation is presented. The method represents the torque twist data by a parametric linear least square model in which Euler and hyperbolic coefficients are used as the parameters. A closed form relationship obtained from the mathematical representation of the data is employed next for flow stress determination. Two different solution strategies, the method of normal equations and singular value decomposition, were used for parametric modelling of the data with hyperbolic basis functions. The performance of both methods is compared. Experimental data obtained by FHTTM, a flexible hot torsion test machine developed at IROST, for a C–Mn austenitic steel was used to demonstrate the method. The results were compared with those obtained using constant strain and strain rate hardening characteristics.

Hamiltonian constraint analysis of vector field theories with spontaneous Lorentz symmetry breaking

Recent investigations of various quantum-gravity theories have revealed a variety of possible mechanisms that lead to Lorentz violation. One of the more elegant of these mechanisms is known as Spontaneous Lorentz Symmetry Breaking (SLSB), where a vector or tensor field acquires a nonzero vacuum expectation value. As a consequence of this symmetry breaking, massless Nambu-Goldstone modes appear with properties similar to the photon in Electromagnetism. This thesis considers the most general class of vector field theories that exhibit spontaneous Lorentz violation-known as bumblebee models-and examines their candidacy as potential alternative explanations of E&M, offering the possibility that Einstein-Maxwell theory could emerge as a result of SLSB rather than of local U(1) gauge invariance. With this aim we employ Dirac's Hamiltonian Constraint Analysis procedure to examine the constraint structures and degrees of freedom inherent in three candidate bumblebee models, each with a different potential function, and compare these results to those of Electromagnetism. We find that none of these models share similar constraint structures to that of E&M, and that the number of degrees of freedom for each model exceeds that of Electromagnetism by at least two, pointing to the potential existence of massive modes or propagating ghost modes in the bumblebee theories.

Characterization on ferrite microstructure evolution during large strain warm torsion testing of plain low carbon steel

Ferrite grain/subgrain structures evolution during the extended dynamic softening of a plain low carbon steel was investigated throughout the large strain warm deformation by hot torsion. Microstructural analysis with electron back-scattering diffraction (EBSD) scanning electron microscope (FEG/SEM) was carried out on the ferrite microstructural parameters. The results showed that the warm flow stress–strain curves are similar to those affected only by dynamic softening and an extended warm flow softening is seen during large strain deformation up to 30. Furthermore, with an increase in strain up to ~ vert, similar1 the grain size of ferrite, misorientation angle and fraction of high-angle boundaries gradually decrease and fraction of low-angle boundaries increases. With a further increase in the strain beyond ~, vert, similar2, these parameters remain approximately unchanged. No evidence of discontinuous dynamic recrystallisation involving nucleation and growth of new grains was found within ferrite. Therefore, the dynamic softening mechanism observed during large strain ferritic deformation is explained by continuous dynamic recrystallization (CDRX).

Constitutive modelling of drawing and extrusion with cyclic torsion

In the current work, constitutive models are developed to describe the cyclic hardening and softening led by the strain path chaneg.  The contribution of deformation conditions such as drawing and extrusion speed, cyclic rotating angle on the drawing and extrusion force will be investigated.  The development of such constitutive models will provide insight into the optimization of operation conditions to explore the potential of industrial applications.

Using job strain and psychological contract theories to predict employee wellbeing in a reformed public sector agency

This study investigates the Issues that contribute to employee wellbeing in a public sector agency having undergone substantial reform The research is based on a model that is initially demand-oriented, and is expanded to incorporate psychological contract breach and organisational justice. Hierarchical regression analyses were conducted on the 1,010 completed surveys The results confirm the value of the Job strain model (JSM) and that the inclusion of breach and fairness were worthwhile extensions of the JSM Future research may wish to extend this approach and incorporate more of the social aspects of the work situation m studies of employee wellbeing.

Theories of international relations

The substantially revised second edition of this widely-used text provides a broad-ranging introduction to the main theoretical approaches to the study of International Relations. The introduction focuses on the nature of theory in the study of global politics and the discipline's internal debates. The following nine substantially revised and updated chapters, including an entirely new one on Constructivism, provide thorough examinations of each of the major traditional and more recent approaches currently prevailing in the discipline.

Theories of international relations

This collection of essays demonstrates the continuing importance of the work of Michael Polanyi for the understanding, not only of the great events of the 20th century, but also of the problems that face us in the 21st century. Polanyi moved liberalism away from a negative, sceptical and rationalist basis towards an acceptance of trust, tradition and faith in transcendent values. His conception of the free society is not one merely of doing as one pleases nor vacuously 'open', but one of individual and communal self-dedication to those values and ideals.These essays, authored by a distinguished international and interdisciplinary panel of invited contributors, examine Polanyi's specific insights in the theory of knowledge, the nature and source of social order and the philosophy of economics and science and draw relevant comparisons between Polanyi and related thinkers such as Popper, Hayek and Mises. This book shows the sources of Polanyi's ideas and his distinctive contribution to philosophy generally, to social and political thought and to economics.

Laminated plate elements based on higher-order shear deformation theories

Efficient and accurate finite elements are crucial for finite element analysis to provide adequate prediction of the structural behavior. A large amount of laminated plate elements have been developed for finite element analysis of laminated composite plates based on the various lamination theories. A recent and complete review of the laminated finite elements based on the higher-order shear deformation theories, including the global higher-order theories, zig-zag theories and the global-local higher-order theories is presented in this paper. Finally some points on the development of the laminated plate elements are summarized.

Integrating job stress and social exchange theories to predict employee strain in reformed public sector contexts

This research examines the organizational characteristics that contribute to employee wellbeing in public sector agencies that have undergone substantial organizational change. Two studies were undertaken, the first involving 2,466 police officers working in a state-based law enforcement agency, whereas the second comprised 1,010 occupationally diverse employees working in a State Government authority. The research was guided by a theoretical framework that begins with a model underpinning many large-scale job stress investigations—the job strain model (JSM)—and is expanded to incorporate widely used social exchange variables (i.e., psychological contract breach and organizational fairness). The results of hierarchical regression analyses from both studies confirm the value of the JSM. There was also strong support for extending the JSM to include the breach and fairness variables; however, proposed interactions between job demands and organizational fairness failed to add to the explanatory value of the model. The implications of these results particularly for public sector organizations that have undergone extensive reforms consistent with New Public Management are discussed.

EBSD analysis of a Ti-IF steel subjected to hot torsion in the ferritic region

The effect of grain size on the warm deformation behaviour of a titanium stabilized interstitial free steel was investigated using hot torsion. Tests were performed at temperatures between 765 °C and 850 °C at strain rates between 0.003 s−1 and 1 s−1 for samples with grain sizes of 25 μm, 75 μm and 150 μm. The structures were observed using EBSD analysis and are consistent with those expected for materials dominated by dynamic recovery. Some evidence was found for small amounts of thermally induced migration of pre-existing boundary (bulging) and for the generation of new segments of high angle boundaries by continuous dynamic recrystallization. The early onset of a steady-state flow stress in the finer grained samples is attributed to one or a combination of thermally induced boundary migration and enhanced rates of recovery near subgrain (and grain) boundaries.

Measuring life balance through discrepancy theories and subjective well-being

The concept of life balance implies that there is some optimal time allocation between the various forms o(human activity we engage in each day. So life balance can be measured by the size of the discrepancy between how we should and how we do allocate our time.
If someone chooses to spend all of their discretionary time writing poetry, is this a balanced life? Many people would say no. They would judge such a life to be imbalanced because life is full of competing demands, and writing poetry all day means that other aspects of life are neglected.
But is this just an imposed value judgment, or does the concept of a balanced life have deeper meaning? The answer must lie with whatever we use to measure the outcome. Any conclusion that balance is better than imbalance must be based on empirical evidence. So, what should be measured?