Spectral element modelling of wave propagation with boundary and structural discontinuity reflections

Spectral element method is very efficient in modelling high-frequency stress wave propagation because it works in the frequency domain. It does not need to use very fine meshes in order to capture high frequency wave energy as the time domain methods do, such as finite element method. However, the conventional spectral element method requires a throw-off element to be added to the structural boundaries to act as a conduit for energy to transmit out of the system. This makes the method difficult to model wave reflection at boundaries. To overcome this limitation, imaginary spectral elements are proposed in this study, which are combined with the real structural elements to model wave reflections at structural boundaries. The efficiency and accuracy of this proposed approach is verified by comparing the numerical simulation results with measured results of one dimensional stress wave propagation in a steel bar. The method is also applied to model wave propagation in a steel bar with not only boundary reflection, but also reflections from single and multiple cracks. The reflection and transmission coefficients, which are obtained from the discrete spring model, are adopted to quantify the discontinuities. Experimental tests of wave propagation in a steel bar with one crack of different depths are also carried out. Numerical simulations and experimental results show that the proposed method is effective and reliable in modelling wave propagation in one-dimensional waveguides with reflections from boundary and structural discontinuities. The proposed method can be applied to effectively model stress wave propagation for structural damage detection.

Enhancing collaboration in BIM-based construction networks through organisational discontinuity theory: a case study of the new Royal Adelaide Hospital

This paper discusses a case study of Australia’s most technologically advanced health facility to address an identified gap in the body of the knowledge. That is, no comprehensive study has hitherto attempted to draw upon virtual team working theories to enhance collaboration in BIM-based construction networks (BbCNs). In response to this, the present study seeks to raise awareness of organisational discontinuity theory (ODT) as a recent theory for virtual teams, which enables BbCNs to embrace collaboration. To this end, the major challenges encountered and corresponding solutions adopted on a mega-project have been closely monitored and investigated. The study contributes to the field through the conceptualisation of typical barriers to collaboration in BbCNs from the perspective of ODT. Additionally, the discussions presented outline practical implications by demonstrating how the identified issues of collaboration in BbCNs could be effectively dealt with.

Drawing on a Foucaultian genealogy to consider the constructions of psychopathology and sexualities in young people

This paper employs genealogical strategies to analyse examples from our own research in education relating to the construction of psychopathology and sexualities. We consider the application of four angles of scrutiny, discontinuity, contingency, emergences and subjugated knowledges (Foucault 1977, 1980, 1988). We explain the four angles of scrutiny and consider how these can be used to produce research practices commensurate with Foucaultian inspired genealogical strategies. For instance, we argue that subjugated knowledges form a critical component of the four angles of scrutiny. We propose that through their subjugation, these knowledges offer a different perspective to dominant knowledges on sexuality and psychopathology. It is our argument that it is precisely via this subjugation that these types of knowledges offer valuable perspectives to the construction of young people. Furthermore, highlighting contingency, discontinuity, emergences and subjugated knowledges makes for provocative moments, both substantively and methodologically, in the task of qualitative analysis.

Is life history a barrier to dispersal? Contrasting patterns of genetic differentiation along an oceanographically complex coast

Extreme variation in early life-history strategies is considered a moderately good predictor of genetic subdivision and hence dispersal for a range of marine species. In reality, however, a good deal of population differentiation must reflect historical effects, more subtle variation in life histories, and, particularly, the interaction of larvae with oceanographic processes. Using a combination of allozyme and microsatellite markers, we show that the large-scale genetic structure of populations of three species (direct and planktonically developing cushion stars and a planktonic developing sea anemone that is also asexually viviparous) varies consistently, in line with the predicted capacity for dispersal within three geographic regions. We detected high levels of genetic subdivision for the direct developing cushion star (FST = 0.6), low levels for the planktonically developing cushion star (FST = 0.009), and intermediate levels for the sexual/asexual sea anmone (FST = 0.19). These patterns are exhibited despite the highly variable patterns of current movement and the presence of biogeographic barriers. Our results suggest that, although there is large scale genetic differentiation for two species, patterns of population connectivity are remarkably consistent within major regions and do not reflect variation in major oceanographic processes or genetic discontinuity coincident with biogeographic boundaries.

Peak modeling approach to accurate assignment of first-dimension retention times in comprehensive two-dimensional chromatography

Modeling of first-dimension retention of peaks based on modulation phase and period allows reliable prediction of the modulated peak distributions generated in the comprehensive two-dimensional chromatography experiment. By application of the inverse process, it is also possible to use the profile of the modulated peaks (their heights or areas) to predict the shape and parameters of the original input chromatographic band (retention time, standard deviation, area) for the primary column dimension. This allows an accurate derivation of the firstdimension retention time (RSD 0.02%) which is equal to that for the non-modulated experiment, rather than relying upon the retention time of the major modulated peak generated by the modulation process (RSD 0.16%). The latter metric can produce a retention time that differs by at least the modulation period employed in the experiment, which displays a discontinuity in the retention time vs modulation phase plot at the point of the 180° out-ofphase modulation. In contrast, the new procedure proposed here gives a result that is essentially independent of modulation phase and period. This permits an accurate value to be assigned to the first-dimension retention. The proposed metric accounts for the time on the seconddimension, the phase of the distribution, and the holdup time that the sampled solute is retained in the modulating interface. The approach may also be based on the largest three modulated peaks, rather than all modulated peaks. This simplifies the task of assigning the retention time with little loss of precision in band standard deviation or retention time, provided that these peaks are not all overloaded in the first or second dimension.

In situ synchrotron SAXS study of polymerizable microemulsions

We present for the first time a real-time small-angle X-ray scattering (SAXS) study of the structural transition of fluid microemulsion to solid polymerized material in a silicone polymerizable microemulsion system. A reactive methacrylate-terminated siloxane macromonomer (MTSM, Mn ∼ 1000 g/mol) was synthesized and used for microemulsion formulations comprising MTSM (oil phase), water, and a mixture of nonionic surfactant (Teric G9A8) with isopropanol. In situ synchrotron SAXS was used to investigate time-dependent nanostructure evolution during the polymerization reaction, which was directly initiated by X-ray radiation. The SAXS data were analyzed using both the Teubner-Strey model and the core-shell model. The results obtained by the Teubner-Strey model showed that the domain size (d) decreased while the correlation length (ξ) increased upon polymerization. The analysis in terms of the core-shell model displayed that adding water to the precursor microemulsion caused the water droplets to start swelling, which resulted in the discontinuity of water in oil microemulsion. There exhibited large differences in morphologies of polymerized materials from the microemulsion formulations with different water and surfactant contents. The core and shell sizes of water droplets decreased during the course of polymerization when there was 15 wt % or more water in the microemulsion formulation; the polymerized material thus exhibited increasingly discrete granular morphology. When there was 10 wt % or less water content in the precursor microemulsion, the rearrangement of water domains could be minimized during the course of polymerization and transparent polymerized material was obtained.

The strange and the familiar : seeing beyond when we know

My novel is a collection of interrelated stories. Each story is framed by the idiosyncrasies and prejudices of a different first-person voice. There are gaps in narrative time and there is disparity between the narrators’ voices. The result is a ‘discontinuous narrative’; this term describes the early work of Frank Moorhouse: ‘an innovative narrative method using interconnected stories’ (Griffith University 2011).
As I draft and re-draft the stories, I am forced to assess the interaction between the voices. I am aware of the disjuncture, and I ask myself: Why not tell the story through the eyes of one narrator? Why not choose a third-person perspective, an omniscient narrator who might collect all of the voices together, in a coherent way?
As I second-guess my approach, I realise that the splintering of voices feels like the right way to tell the story and, in this way, I approach the question of methodology. I am aware that a sense of disjuncture arises out of the medley of voices, but I also realise that the disjuncture is carefully constructed; it is not accidental. This is an intuitive judgement.
If I edit my novel ethically, I ask what the discontinuity achieves, rather than how it fails in the context of logic. This means that I recognise that the narrative begins from a place that does not worry about logic, and I realise that second-guessing the surface content of the narrative, from a rational perspective, may be counterproductive.
The conscious mind, fettered as it is with inhibitions, may fail to see that the logical track is not necessarily the most productive route. The conscious mind may not recognise that going off-track is the way forward and, perhaps, the only way that the story can become something other than what I, in my rational mind, believe that it should be.
Ethical editing means that I am attentive to my intuitive response to the narrative; it means that I tolerate incongruous elements of the narrative, even if they do not fit the criteria of logic.
Ethical editing is a meeting of minds (both mine); the fully conscious mind meets the work of the subconscious mind with surprise and approval, at best, skepticism and derision, at worst. The work of the subconscious mind is elusive but it need not be subjugated to logical, rational considerations, for this means that I delimit the work of the subconscious; it means I assess the discontinuity on the basis of an external operating system; it means that I impose certain criteria upon the surface narrative, criteria that has nothing to do with understanding why the discontinuity exists in the first instance.
Alternatively, when I pay heed to a primal moment of narrative composition, a moment that is not necessarily consciously determined or logical, I apprise the surface of the narrative as a metaphorical map, I attempt to engage with the possibilities for meaning that the map encompasses; this constitutes a quest for the unstable how of meaning attribution.

Pressure-induced structural transitions in MOO3·xH2O (x = 1/2, 2) molybdenum trioxide hydrates : a raman study

The high-pressure behaviors of M_OO₃·1/2H₂O and M_OO₃·2H₂O have been investigated by Raman spectroscopy in a diamond anvil cell up to 31.3 and 30.3 GPa, respectively. In the pressure range up to around 30 GPa, both M_OO₃·1/2H₂O and M_OO₃·2H₂O undergo two reversible structural phase transitions. We observed a subtle structural transition due to O−H···O hydrogen bond in M_OO₃·1/2H₂O at 3.3 GPa. We found a soft mode phase transition in M_OO₃·2H₂O at 6.6 GPa. At higher pressures, a frequency discontinuity shift and appearance of new peaks occurred in both M_OO₃·1/2H₂O and M_OO₃·2H₂O, indicating that the second phase transition is a first-order transition. The frequency redshift of the O−H stretching bands of M_OO₃·1/2H₂O and M_OO₃·2H₂O are believed to be related to the enhancement of the O−H···O weak hydrogen bonds under high pressures.

π-Selective stationary phases: (I) Influence of the spacer chain length of phenyl type phases on the aromatic and methylene selectivity of aromatic compounds in reversed phase high performance liquid chromatography

Phenyl type stationary phases of increasing spacer chain length (phenyl, methyl phenyl, ethyl phenyl, propyl phenyl and butyl phenyl, with 0–4 carbon atoms in the spacer chain, respectively) were synthesised and packed in house to determine the impact that the spacer chain length has on the retention process. Two trends in the aromatic selectivity, q_aromatic, were observed, depending on whether the number of carbon atoms in the spacer chain is even or odd. Linear log k′ vs ϕ plots were obtained for each stationary phase and the S coefficient was determined from the gradient of these plots. For the phenyl type phases, the S vs n_c plots of the retention factors of linear polycyclic aromatic hydrocarbons vs the number of rings exhibit a distinct discontinuity that between 3 and 4 rings, which increases with increasing spacer chain length for even phases but decreases for odd phases. Accordingly, we suggest that the retention factors depend differently on the number of carbon atoms in the spacer chain depending on whether this number is even or odd and that this effect is caused by different orientations of the aromatic ring relative to the silica surface.

Design and simulation of a high isolation RF MEMS shunt capacitive switch for C-K band

This paper presents a wide band RF MEMS capacitive switch. The LC resonant frequency is reduced from mm wave to X band frequencies at down-state by using a meander type membrane, with the frequency band is being increased by adding two short high impedance lines at both ends of coplanar waveguide (CPW). Moreover, this acts as T-match circuit in up-state position and improves the matching. Simulation results demonstrate that the capacitance ratio reduces from 50 to 21.4, S21 and S11 are less than −10dB for the entire frequency band at down-state and up-state. Also, a comprehensive and complete electric model of the switch is proposed and simulation results agree well with the characteristics of the physical structure of the MEMS switch. Vpull-in and Vpull-out of this switch are 8.1V and 0.3V, respectively.

Mentoring programs for indigenous youth at-risk

There is a range of risk factors that may make young people of any ethnicity more likely to engage in antisocial behaviours. These factors include the young person’s own attitudes; relationships within the family; and growing up in communities where there is widespread violence, alcohol and other substance abuse, poverty, poor health and poor-quality housing. Indigenous young people face the additional challenges ofdispossession, discontinuity of culture and intergenerational trauma.A strong connection to culture—coupled with high self-esteem, a strong sense of autonomy, and with living in cohesive, functioning families and communities—can be protective factors that result in Indigenous young people choosing productive life pathways.Mentoring is a relationship intervention strategy that can assist in building some of these protective factors. A growing body of research demonstrates that mentoring can have powerful and lasting positive effects in improving behavioural, academic and vocational outcomes for at-risk youth and, to a more limited extent, in reducing contact with juvenile justice systems.In an Indigenous context, mentoring is a particularly promising initiative because it fits well with Indigenous teaching and learning styles and can help to build strong collective ties within a community.Mentoring programs can involve adult or peer mentors and can be implemented in a range of ways, such as one-on-one or in groups.Although positive results can be achieved with single-intervention mentoring for at risk youth, integrating mentoring into broader programs produces a greater level of positive change.The way the mentoring program is run and the nature of the relationship between mentor and mentee are crucial in determining the outcomes of youth mentoring programs.