91 research outputs found

    Combining Image Processing Techniques and Mobile Sensor Information for Marker-less Augmented Reality Based Reconstruction

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    Marker-less Augmented Reality(AR) based recon- struction using mobile devices, is a near impossible task. When considering vision based tracking approaches, it is due to the lack of processing power in mobile devices and when considering mobile sensor based tracking approaches, it is due to the lack of accuracy in mobile Global Positioning System(GPS). In order to address this problem this research presents a novel approach which combines image processing techniques and mobile sensor information which can be used to perform precise position localization in order to perform augmented reality based reconstruction using mobile devices. The core of this proposed methodology is tightly bound with the image processing technique which is used to identify the object scale in a given image, which is taken from the user’s mobile device. Use of mobile sensor information was to classify the most optimal locations for a given particular user location. This proposed methodology has been evaluated against the results obtained using 10cm accurate Real-Time Kinematic(RTK) device and against the results obtained using only the Assisted Global  Positioning  System(A-GPS)  chips  in  mobile  devices. Though  this  proposed  methodology  require  more  processing time than A-GPS chips, the accuracy level of this proposed methodology outperforms that of A-GPS chips and the results of the experiments carried out further convince that this proposed methodology facilitates improving the accuracy of position local- ization for augmented reality based reconstruction using mobile devices under certain limitations

    Toward effective structural identification of medium-rise building structures

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    Structural Identification (St-Id) is the process of constructing and calibrating a physics-based model based on the measured static and/or dynamic response of the structure. Over the last two decades, although the St-Id methods have become increasingly popular amongst civil-structural engineering communities, most complete and successful applications are often found with flexible structures such as long-span bridges and towers. Very few comprehensive studies were reported on building structures, especially those with medium-rise characteristics which are often associated with complicated analytical modelling and different degrees of parameter uncertainties. To address this need, this paper presents an in-depth study on St-Id of a benchmark medium-rise building firstly demonstrating the importance of developing appropriate initial analytical models that can be used for the automated model calibration techniques. Then, a novel parametric study based sensitivity analysis approach is introduced to identify tuning parameters as well as their appropriate ranges to maximise the correlation of the calibrated model whilst preserving the physical relevance of the calibrated model. Modal data of the first few modes measured under ambient vibration conditions are used in this study

    Environmentally friendly packaging materials from renewable resources as alternatives for oil-based polymers

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    Nearly 60 m tonnes of waste is produced annually in Europe from “plastic packaging” engendering significant challenges for legislative controls and minimisation of environmental impact. There is an increasing demand for biodegradable packaging, which can be disposed of with minimum environmental impact, but the growing market is still in its infancy predominantly due to a lack of materials having environmental, practical and economic suitability. This research project dealt with some processing challenges of environmentally friendly packaging materials from renewable resources, as a long term solution to mitigate some issues associated with oil based plastic packaging. In this work, novel Polylactic acid (PLA) and starch based composites were developed with the requisite technical properties to fill the gap in the food packaging and cosmetic packaging industry. It was found that starch can be incorporated in a PLA matrix at the 10% level without difficulty in processing in the presence of 2% methyldiphenyl diisocyante. The blend shows properties similar to pure PLA. It was also found that the elongation at break and impact properties of PLA can be increased remarkably by the addition of a biostrength impact modifier. Furthermore, mixing of PLA and starch in the blend is efficient when the PLA particle size is reduced. It was also found that flexible and tougher PLA/starch blend pellets, that can be injection moulded, can be produced by an extrusion process with a range of additives. Each additive has a maximum level that exhibits optimum properties. The blends also established that 15% starch can be incorporated into the PLA matrix to reduce the cost without any processing difficulties. Encouragingly, the presence of an impact modifier in the PLA/starch blends has shown more desirable properties. Furthermore, the mechanical properties of the pellets exposed to increased residence time in the injection moulding barrel and of the test specimens stored for 9 months at 21ºC were also satisfactory for the new blend. The overall results exhibited some attractive properties in the tri blend system, which can be easily adopted by the plastics industry for development of an injection moulded product within the scope of applications such as dry food packaging or cosmetic packaging. A further finding of this project is that biodegradation under a home composting environment can be improved by incorporating starch and certain other modifiers into PLA.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

    Reconciling nature, people and policy in the mangrove social-ecological system through the adaptive cycle heuristic

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    © 2021 The Authors. While mangroves are increasingly described as social-ecological systems (SESs), performing SES research is so much more than merely documenting local resource utilisation patterns in case studies. The aim of this paper is to review and show how ecological, human and institutional resilience could be understood and fostered in an era of uncertainty, through the adaptive cycle (AC) heuristic. Uncertainties come in many forms and shapes: climate change, social and economic dynamics, natural disasters, political and institutional disruption and ever-increasing public demands for participation. Social-ecological studies form windows of experimentation that can provide insights beyond their case-specific context. In order to synthesise and structure the cumulative knowledge base arising from existing and future studies, the need for a suitable overarching framework arose. Here, the AC heuristic represents the connectedness between variables of the mangrove SES versus the mangrove's accumulated capital (natural, built, human and social). We posit that the AC heuristic can be used to interpret spatial and temporal changes (ecological, social, economic, political) in mangrove SESs and we exemplify it by using the 2004 Indian Ocean tsunami as well as a century-long silviculture case. The AC, combined with the SES scheme, allows integration of the spato-temporal dynamics and the multi-dimensional character of mangrove SESs. We also reviewed the ecosystem functions, services and disservices of mangrove SESs, linking each of them to SES capital and variable (fast or slow) attributes, which in turn are closely linked to the different axes and phases of the AC. We call upon mangrove scientists from the natural, applied, social and human sciences to join forces in fitting diversified empirical data from multiple case studies around the world to the AC heuristic. The aim is to reflect on and understand such complex dynamic systems with stakeholders having various (mutual) relationships at risk of breaking down, and to prepare for interactive adaptive planning for mangrove forests.Belgian Science Policy Office ‘EVAMAB – Economic valuation of ecosystem services in Man & Biosphere Reserves' - BELSPO (BL/58/UN32); Erasmus Mundus Masters Course in Tropical Biodiversity and Ecosystems (TROPIMUNDO); VLIR-UOS-funded GREENDYKE Project (ZEIN2008PR347); BELSPO-funded MAMAFOREST-Project (SR/00/323); ZMT Academy travel grant; Singapore National Parks Board (NParks); TUYF Charitable Trust; HKU Seed Fund for Research; International Coral Reef Initiative (ICRI); UNEP/GEF Blue Forest Project; Pew Charitable Trust; Department of Science and Technology, India INSPIRE Faculty scheme (IFA18-LSPA111)

    Diversity of Staphylococcus aureus Isolates in European Wildlife

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    Staphylococcus aureus is a well-known colonizer and cause of infection among animals and it has been described from numerous domestic and wild animal species. The aim of the present study was to investigate the molecular epidemiology of S. aureus in a convenience sample of European wildlife and to review what previously has been observed in the subject field. 124 S. aureus isolates were collected from wildlife in Germany, Austria and Sweden; they were characterized by DNA microarray hybridization and, for isolates with novel hybridization patterns, by multilocus sequence typing (MLST). The isolates were assigned to 29 clonal complexes and singleton sequence types (CC1, CC5, CC6, CC7, CC8, CC9, CC12, CC15, CC22, CC25, CC30, CC49, CC59, CC88, CC97, CC130, CC133, CC398, ST425, CC599, CC692, CC707, ST890, CC1956, ST2425, CC2671, ST2691, CC2767 and ST2963), some of which (ST2425, ST2691, ST2963) were not described previously. Resistance rates in wildlife strains were rather low and mecA-MRSA isolates were rare (n = 6). mecC-MRSA (n = 8) were identified from a fox, a fallow deer, hares and hedgehogs. The common cattle- associated lineages CC479 and CC705 were not detected in wildlife in the present study while, in contrast, a third common cattle lineage, CC97, was found to be common among cervids. No Staphylococcus argenteus or Staphylococcus schweitzeri-like isolates were found. Systematic studies are required to monitor the possible transmission of human- and livestock- associated S. aureus/MRSA to wildlife and vice versa as well as the possible transmission, by unprotected contact to animals. The prevalence of S. aureus/MRSA in wildlife as well as its population structures in different wildlife host species warrants further investigation

    Multimedia communications over 3G wireless communication systems.

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    This thesis addresses the transmission of video over third generation radio access networks. The first part of the thesis investigates the capabilities of Universal Terrestrial Radio Access Networks (UTRAN) in terms of the provision of multimedia communications. The error performance and traffic requirements of real-time video transmission over circuit switched and packet switched connections are examined. The effect of network parameter settings upon video performances is evaluated, and optimum radio bearer configurations for the transmission of video are derived. A method of estimating received video quality after transmission over error prone environments is developed. The quality estimation is based on a distortion model, which accurately models the overall distortion seen in decoder frame reconstruction. This includes quantisation distortion, concealment distortion, and error propagation. Based on the developed performance model, optimum MTU (Maximum Transfer Unit) size for efficient wireless video communications over a packet switched access network is derived. The second part of the thesis investigates quality enhancement techniques for multimedia traffic transmitted over wireless channels. Quality enhancement is achieved at three levels of the transmission process: link level, application level and system level. Link level quality enhancement techniques are designed to optimise the allocation of link level parameter values according to the media characteristics. A novel Unequal Error Protection scheme and a novel Unequal Power Allocation scheme are designed to exploit the inherent diversity in the subjective importance of different sections of compressed media. The algorithms are developed and analysed for transmission of video over 3G wireless systems. The effectiveness of these algorithms is demonstrated through the results of simulated transmission over a UMTS channel. Application level quality enhancement techniques are designed to explore the time-varying nature of the wireless channel. A number of link adaptation schemes are proposed for real time video communication and real-time video streaming over 3G wireless systems. These algorithms are designed to enhance the perceptual video quality, and the system utilisation. This is achieved by adapting the allocated radio network parameters and the source parameters, according to a feedback channel condition. Simulation results show a significant performance improvement compared to non-adaptive schemes. Finally, system level adaptation techniques are designed for efficient radio resource allocation in multi-user scenarios. Two adaptive resource allocation schemes are proposed and analysed for real-time video communications in a UMTS system. The proposed algorithms are shown to provide improved performances in terms of average received video quality and user satisfaction. Key words: Wireless Communication, Multimedia communication. Video Transmission

    Multimedia communications over 3G wireless communication systems

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    EThOS - Electronic Theses Online ServiceGBUnited Kingdo

    Laboratory Investigation of Desiccation Cracking

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