Sharp

Poetry by Kasey Kirchner

The problem of offset in acoustic pulse reflectometry

Acoustic pulse reflectometry has become established as a useful non-invasive technique for measuring a variety of duct properties. A sound pulse is injected into the duct under investigation and the resultant reflections are recorded. Suitable analysis of the reflections yields the input impulse response of the duct, from which both its input impedance and its internal dimensions can be calculated. However, an input impulse response measurement made using acoustic pulse reflectometry generally contains an offset. Unless this offset is removed, the application of a bore reconstruction algorithm results in a calculated duct profile which expands or contracts spuriously. In this paper, the offset in an input impulse response measurement is shown to consist of both constant and time-varying components. Methods of preventing or removing these DC and time-varying offsets are proposed and subsequent improvements to the bore reconstruction accuracy are demonstrated

An optimisation approach to the location and sizing of multiple leaks in a duct

A single leak in a duct can be located, and its size predicted, by measuring the input impedance of the duct and then solving an inverse problem. However, extending this procedure to a duct containing several leaks is non-trivial, with the resulting mathematical expressions proving to be highly complex. In this paper, an optimisation approach to the location and sizing of multiple leaks in a duct is described. The approach employs a standard theoretical model of a duct that contains several leaks. The initial parameters of the duct model (e.g. duct radius, number of leaks, leak positions and sizes) are chosen arbitrarily. An optimisation function then adjusts the parameters of the model until its input impedance matches the measured impedance of the duct under investigation. Results are presented which demonstrate the success of this optimisation approach in both locating and sizing multiple leaks in a duct

Sustainable development : a model Indonesian SRI co-operative : this research paper is presented in partial fulfilment of the requirements for the degree of Master of International Development, Massey University, New Zealand

This research report explores how ‘sustainable livelihoods’ have been achieved at a model cooperative using the ‘System of Rice Intensification’ named SIMPATIK. To conduct the research a novel template was developed. The framework was required following a review of sustainable livelihood literature which found deficiencies with the ‘sustainable livelihoods framework’, particularly its treatment of equity, social capital, culture and agro-ecology which disqualified the framework as an appropriate approach for the research. Amekawa’s (2011) ‘Integrated Sustainable Livelihoods Framework’ which synthesises agro-ecology and the sustainable livelihoods framework is then discussed. Further work is then presented on social capital which this paper argues has a critical role in facilitating access to livelihood capitals. A discussion of the significance of culture then follows to underline its importance as a form of livelihood capital. The research then introduces an operational model that is appropriate to the local cultural, institutional and geographical context to demonstrate how livelihood capitals are linked to livelihood outcomes, a model I have labelled the ‘Apt-Integrated Sustainable Livelihoods Framework’. This framework is then informed through field research at the SIMPATIK co-operative. Impact pathways through ‘synergetic forms of social capital’ and the System of Rice Intensification (SRI) are shown indeed to lead to sustainable livelihood outcomes for research participants. The ‘sequencing’ of livelihood capitals is seen to be critical and the research culminates in the development of a ‘SRI Co-operative Template for Sustainable Livelihoods’; a transferable model that shows how SRI can be promoted as a sustainable livelihood strategy

Outer edges of debris discs: how sharp is sharp?

Ring-like features have been observed in several debris discs. Outside the main ring, while some systems exhibit smooth surface brightness profiles (SB) that fall off roughly as r**-3.5, others display large luminosity drops at the ring's outer edge and steeper radial SB profiles. We seek to understand this diversity of outer edge profiles under the ``natural'' collisional evolution of the system, without invoking external agents such as planets or gas. We use a statistical code to follow the evolution of a collisional population, ranging from dust grains (submitted to radiation pressure) to planetesimals and initially confined within a belt (the 'birth ring'). The system typically evolves toward a "standard" steady state, with no sharp edge and SB \propto r**-3.5 outside the birth ring. Deviations from this standard profile, in the form of a sharp outer edge and a steeper fall-off, occur only when two parameters take their extreme values: 1) When the birth ring is so massive that it becomes radially optically thick for the smallest grains. However, the required disc mass is here probably too high to be realistic. 2) When the dynamical excitation of the dust-producing planetesimals is so low ( <0.01) that the smallest grains, which otherwise dominate the total optical depth, are preferentially depleted. This low-excitation case, although possibly not generic, cannot be ruled out by observations. Our "standard" profile provides a satisfactory explanation for a large group of debris discs with outer edges and SB falling as r**-3.5. Systems with sharper outer edges, barring other confining agents, could still be explained by ``natural'' collisional evolution if their dynamical excitation is very low. We show that such a dynamically-cold case provides a satisfactory fit for HR4796AComment: Accepted for publication in A&A (abstract truncated here, full version in the pdf file); v2: typos corrected + rephrasing title of Section 5.1.2; v3 :final technical change

Central American Temnocerus Thunberg, 1815 (Coleoptera: Rhynchitidae)

Twenty eight species of Temnocerus Thunberg, 1815 are recognized from Central America (Mexico to Panama) with eight previously described species and 20 new species as follows: T. abdominalis (Voss), T. chiapensis n. sp., T. chiriquensis (Sharp), T. confertus (Sharp), T. cyaneus n. sp., T. ellus n. sp., T. giganteus n. sp., T. guatemalenus (Sharp), T. guerrerensis n. sp., T. herediensis n. sp., T. mexicanus n. sp., T. michoacensis n. sp., T. minutus n. sp., T. niger n. sp., T. oaxacensis n. sp., T. obrieni, n. sp., T. oculatus (Sharp), T. potosi n. sp., T. pseudaeratus n. sp., T. pueblensis n. sp., T. pusillus (Sharp), T. regularis (Sharp), T. rostralis n. sp., T. rugosus n. sp., T. salvensis n. sp., T. tamaulipensis n. sp., T. thesaurus (Sharp) and T. yucatensis n. sp. Rhynchites debilis Sharp is placed in synonymy with Temnocerus guatemalenus (Sharp) and Pselaphorhynchites lindae Hamilton is placed in synonymy with Temnocerus regularis (Sharp). A key to species based on external characters and male genitalia is provided as well as digital images, aedeagus drawings, and map distributions

Optimal Extraction of Fibre Optic Spectroscopy

We report an optimal extraction methodology, for the reduction of multi-object fibre spectroscopy data, operating in the regime of tightly packed (and hence significantly overlapping) fibre profiles. The routine minimises crosstalk between adjacent fibres and statistically weights the extraction to reduce noise. As an example of the process we use simulations of the numerous modes of operation of the AAOmega fibre spectrograph and observational data from the SPIRAL Integral Field Unit at the Anglo-Australian Telescope.Comment: Accepted for publication in PAS