1,640 research outputs found

    On-the-go machine vision sensing of cotton plant geometric parameters: first results

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    Plant geometrical parameters such as internode length (i.e. the distance between successive branches on the main stem) indicate water stress in cotton. This paper describes a machine vision system that has been designed to measure internode length for the purpose of determining real-time cotton plant irrigation requirement. The imaging system features an enclosure which continuously traverses the crop canopy and forces the flexible upper main stem of individual plants against a glass panel at the front of the enclosure, hence allowing images of the plant to be captured in a fixed object plane. Subsequent image processing of selected video sequences enabled detection of the main stem in 88% of frames. However, node detection was subject to a high false detection rate due to leaf edges present in the images. Manual identification of nodes in the acquired imagery enabled measurement of internode lengths with 3% standard error

    Simulation of site-specific irrigation control strategies with sparse input data

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    Crop and irrigation water use efficiencies may be improved by managing irrigation application timing and volumes using physical and agronomic principles. However, the crop water requirement may be spatially variable due to different soil properties and genetic variations in the crop across the field. Adaptive control strategies can be used to locally control water applications in response to in-field temporal and spatial variability with the aim of maximising both crop development and water use efficiency. A simulation framework ‘VARIwise’ has been created to aid the development, evaluation and management of spatially and temporally varied adaptive irrigation control strategies (McCarthy et al., 2010). VARIwise enables alternative control strategies to be simulated with different crop and environmental conditions and at a range of spatial resolutions. An iterative learning controller and model predictive controller have been implemented in VARIwise to improve the irrigation of cotton. The iterative learning control strategy involves using the soil moisture response to the previous irrigation volume to adjust the applied irrigation volume applied at the next irrigation event. For field implementation this controller has low data requirements as only soil moisture data is required after each irrigation event. In contrast, a model predictive controller has high data requirements as measured soil and plant data are required at a high spatial resolution in a field implementation. Model predictive control involves using a calibrated model to determine the irrigation application and/or timing which results in the highest predicted yield or water use efficiency. The implementation of these strategies is described and a case study is presented to demonstrate the operation of the strategies with various levels of data availability. It is concluded that in situations of sparse data, the iterative learning controller performs significantly better than a model predictive controller

    Commercialisation of precision agriculture technologies in the macadamia industry

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    A prototype vision-based yield monitor has been developed for the macadamia industry. The system estimates yield for individual trees by detecting nuts and their harvested location. The technology was developed by the National Centre for Engineering in Agriculture, University of Southern Queensland for the purpose of reducing labour and costs in varietal assessment trials where yield for individual trees are required to be measured to indicate tree performance. The project was commissioned by Horticulture Australia Limited

    The path to fracture in granular flows: dynamics of contact networks

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    Capturing the dynamics of granular flows at intermediate length scales can often be difficult. We propose studying the dynamics of contact networks as a new tool to study fracture at intermediate scales. Using experimental three-dimensional flow fields with particle-scale resolution, we calculate the time evolving broken-links network and find that a giant component of this network is formed as shear is applied to this system. We implement a model of link breakages where the probability of a link breaking is proportional to the average rate of longitudinal strain (elongation) in the direction of the edge and find that the model demonstrates qualitative agreement with the data when studying the onset of the giant component. We note, however, that the broken-links network formed in the model is less clustered than our experimental observations, indicating that the model reflects less localized breakage events and does not fully capture the dynamics of the granular flow.Comment: 15 pages, 6 figures, accepted for publication in Phys. Rev.

    Superconducting fault current limiter application in a power-dense marine electrical system

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    Power-dense, low-voltage marine electrical systems have the potential for extremely high fault currents. Superconducting fault current limiters (SFCLs) have been of interest for many years and offer an effective method for reducing fault currents. This is very attractive in a marine vessel in terms of the benefits arising from reductions in switchgear rating (and consequently size, weight and cost) and damage at the point of fault. However, there are a number of issues that must be considered prior to installation of any SFCL device(s), particularly in the context of marine applications. Accordingly, this study analyses several such issues, including: location and resistance sizing of SFCLs; the potential effects of an SFCL on system voltage, power and frequency; and practical application issues such as the potential impact of transients such as transformer inrush. Simulations based upon an actual vessel are used to illustrate discussions and support assertions. It is shown that SFCLs, even with relatively small impedances, are highly effective at reducing prospective fault currents; the impact that higher resistance values has on fault current reduction and maintaining the system voltage for other non-faulted elements of the system is also presented and it is shown that higher resistance values are desirable in many cases. It is demonstrated that the exact nature of the SFCL application will depend significantly on the vessel’s electrical topology, the fault current contribution of each of the generators, and the properties of the SFCL device, such as size, weight, critical current value and recovery time

    Visualising complex networks within humanities data for discovery and analysis

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    This paper describes the preliminary work leading to a project to build a web services visualisation tool that addresses the multi‐dimensional metadata used to describe cultural datasets, especially those created by researchers to meet specific research ends. The project will utilise the Knalij service developed by Steven Melnikoff (Information Physics, The University of Melbourne) together with datasets curated using the eScholarship Research Centre’s Online Heritage Resource Manager (OHRM) system. In the first instance it is proposed that the Encyclopedia of Australian Science and the Australian Women’s Register datasets be used to operationalise the tool. Using offline visualisation tools, the study of both embedded and implied complex network structures within standards‐based Humanities datasets has revealed significant potential for analysis, navigation, discovery, and the development of new research methods. In October 2011 Knalij was awarded the USA challenge.gov prize for the most innovative uses of National Library of Medicine data. Knalij offers an interactive web service that can visualise the whole of PubMed in real time. This is a landmark achievement that opens up web services, real‐time visualisation capability for complex Humanities datasets with both synchronic and diachronic variables. As noted in the Knalij press release in October: ‘We visualized the entirety of cancer research since 1800 and displayed the progression through the decades. Our maps are searchable, interactive, and ready for researchers to discover trends, patterns, and connections. This is the first time that anyone has visually displayed the entire scope of cancer research in one searchable application. We are very excited to present this to the world'. The paper will focus on Australian Humanities research‐driven datasets and explore a range of uses from project management and documentation to the revelation of novel insights and understandings.Australian Academy of the Humanities; the ANU College of Arts and Social Science

    The beginning of 'striker foot' (Pes equinus varus) with severe stroke patients

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    An exploratory investigation into identifying the answers to two specific questions related to this condition. 1. Why do many individuals develop 'striker foot' following severe stroke? 2. What is the best intervention to help control its development? The answer to the first question lies within the lack of stability in the paretic leg when the patient attempts to move in bed using the other leg. With the second question the answer is less obvious, although there are indications that greater stability helps to maintain the muscular tone of the calf leading to better overall control. Throughout this investigation the only changing factor with stability was the mattress which suggested that more would be required to prevent 'striker foot' developing. Therefore further investigations are needed to gain a better understanding and help to reduce the numbers of severe stroke patients who go on to develop this condition

    Diagonals part one

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    The diagonals are muscle structures that hold and moves our body. In this article (part one) we explore the development of these diagonals from childhood and the enhancement of them in professional athletes Part two will then explore what happens when neurological diseases damage these muscle pattern. Neurological disease will affect how the diagonals work more than orthopedic diseases, due to its dependency on structures within the brain. Although these parts of the brain are not yet identified the innervation of the spine and the large joints give us a clear picture that one hemisphere controls both parts. The overall distribution is unequal (between 90%-10%) but this amount of variation in the distribution is what enables the diagonals to work in this way

    Diagonals part seven. Stroke 5. Walking: what say the scientist and what is best practice

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    In this part we try to listen to the science, that has and still do over the whole world investigation by stroke patients over the walking aspect and the best way to get the best recovery or compensation. Recovery is only for a group possible, that had an “minor” stroke and there we see that the old system is not too much damaged and recovery is possible. But with greater damage of the brain individual after a stroke must go another way to get his independently and that is compensation. That compensation starts with the first movement in bed and will also affect the diagonal. The science has reported that the walking pattern on the EMG don’t change very much after a short period and they said that this pattern is fixed within in certain period. We have our doubt and have search to other forms of training and learning and see that changes is well possible but to be sure the science must have investigated that. Here is a problem because science gives another interpretation of the word intensity. For the scientist this is “more time” to do the exercises and in our view, it is the heaviness of the exercises and that can be done by an individual with a stroke a certain time before he is fatigue. In the treatment we start with the individual with a severe stroke that need all assistance to get him on his feet and will have need of a splint on his knee because the power in the knee muscle is to limited, to hold the knee. Regrettable an individual after a stroke that the scientist never investigates because this is too difficult. From this starting point we walk through all the steps, we must make to get independent walking individual when possible and what the problem were when that goal cannot fully be reached. And we discuss other forms, approach or new development to get walking possible with the use of the diagonals. Part 8 will discuss other cases with a severe stroke

    Diagonals part two: assessment and trunk rules

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    Part two describes the assessment process of the diagonals, including the front, back and homolateral structures. We discuss various positions for assessment including patients laying down on their back and side, sitting and standing. We also look at the use of the balance reaction test Statiek to assess the capability of both the diagonals and homolateral structures. This provides a greater understanding of what the diagonals can do, and what would be considered normal or abnormal as assessing both gives the examiner a greater appreciation of what to expect. We can use this practice to increase our awareness of what to observe and feel for, identifying some tips of where to place your hands to enable you to both apply pressure and feel for the amount of resistance the patient can apply in response. Subtle differences can be observed in patients depending on various individual characteristics they may have such as different leg lengths when comparing the left and right sides, or if somebody has a recognized problems within the structure and function of their backs. We begin to describe “trunk rules” as everyone should has the same reaction response when performing movements but these can present differently depending on the individuals level of mobility and selectivity. This article starts to briefly consider body scheme which is the perception of the body and its influence on the reaction of muscle patterns This perception can alter the overall function of the diagonals. In part three Pathology we will go more into developing the understanding of the impact that perception plays in the control and movement of diagonals. In the final section we move on to describing the trunk rules, discussing how both diagonals and the homolateral structures work in collaboration to help control and enable a greater range of movements of the trunk, and how this supports the keypoints of the great joints, identifying which movements are enabled and which are restricted