639 research outputs found
Morphometric Otolith Analysis
Abstract
Fish otoliths have long played an important role in sustainable �sheries management.
Stock assessment models currently used rely on species speci�c age pro�les obtained
from the seasonal patterns of growth marks that otoliths exhibit. We compare methods
widely used in �sheries science (elliptical Fourier) with an industry standardised
encoding method (MPEG7 - Curvature-Scale-Space) and with a recent addition to
shape modelling techniques (time-series shapelets) to determine which performs best.
An investigation is carried out into transform methods that retain size-information,
and whether the boundary encoding method is impacted be otolith age, performing
tests over three 2-class otolith datasets across six discrete and concurrent age groups.
Impact of segmentation methods are assessed to determine whether automated or expert
segmented methods of boundary extraction are more advantageous, and whether
constructed classi�ers can be used at di�erent institutions.
Tests show that neither time-series shaplets nor Curvature-Scale-Space methods
o�er any real advantage over Fourier transform methods given mixed age datasets.
However, we show that size indices are most indicative of �sheries stock in younger
single-age datasets, with shape holding more discriminatory potential in older samples.
Whilst commonly used Fourier transform methods generally return best results;
we show that classi�cation of otolith boundaries is impacted by the method of boundary
segmentation. Hand traced boundaries produce classi�ers more robust to test data
segmentation methods and are more suited to distributed classi�ers.
Additionally we present a proof of concept study showing that high energy synchrotron
scans are a new, non-invasive method of modelling internal otolith structure,
allowing comparison of slices along near in�nite numbers of virtual complex planes
A DYNAMIC ANALYSIS OF THE IMPACT OF WATER QUALITY POLICIES ON IRRIGATION INVESTMENT AND CROP CHOICE DECISIONS
A dynamic model is developed to analyze farmers' irrigation investment and crop choice decisions under alternative water quality protection policies. The model is applied to an empirical example in the Oklahoma High Plains. The choices of crops and irrigation systems and the resulting levels of irrigation, income, and nitrogen runoff and percolation are simulated over a ten-year period. An effluent tax on nitrogen runoff and percolation is shown to be effective in reducing nitrate pollution. The efficacy of cost sharing in adopting modern irrigation technologies and restrictions on irrigation water use depends on soil type. A tax on nitrogen use is shown to be the least effective policy.Crop selection, Dynamic optimization, Irrigation investment, Water quality, Crop Production/Industries,
Building an intelligent edge environment to provide essential services in smart cities
Smart Cities will cause major societal change because they will provide a comprehensive set of key services including seamless communication, intelligent transport systems, advanced healthcare platforms, urban and infrastructure management, and digital services for local and regional government. Thus, a new service and networking environment which will provide low latency and sustainable high bandwidth is needed to build new applications and services for smart cities. In this system services will be managed from the edge of the Internet and not from the centre as they currently are. This represents a new computing paradigm which is called the Intelligent Edge Environment. This paper looks at how to build this new ecosystem. Firstly, a new framework which comprises seven layers is unveiled, showing the functions that must be supported to realise this brave new world. New mechanisms are then introduced and a small prototype is developed to support storage in highly mobile environments. The results show that this approach could be used to build smart city digital platforms. The paper ends by discussing the development of a Distributed Operating System for smart cities
Developing an implementation framework for the future internet using the Y-Comm architecture, SDN and NFV
The Future Internet will provide seamless connectivity via heterogeneous networks. The Y-Comm Architecture is a reference model that has been developed to build future mobile systems for heterogeneous environments. However, the emergence of Software Defined Networking and Network Functional Virtualization will allow the implementation of advanced mobile architectures such as Y-Comm to be prototyped and explored in more detail. This paper proposes an implementation model for the Y-Comm architecture based on these mechanisms. A key component is the design of the Core Endpoint which connects various peripheral wireless networks to the core network. This paper also proposes the development of a Network Management Control Protocol which allows the management routines running in the Cloud to control the underlying networking infrastructure. The system being proposed is flexible and modular and will allow current and future wireless technologies to be seamlessly integrated into the overall system
A QoS-based flow assignment for traffic engineering in software-defined networks
In order to meet a tremendous amount of data storage requirement in next-generation wireless networks, an increasing number of cloud data centers has been deployed around the world. The underlying core networks are expected to provide the ability to store data in a dynamic and scalable computing environment. The traditional Internet Protocol (IP) has shown to be restricted due to its static architecture, which accordingly motivates the development of Software-Defined Networks (SDNs). In the SDNs, Traffic Engineering (TE) is simpler and programmable with a controller without the requirement of reconfiguration for all network devices. However, the existing TE algorithm of the SDNs rejects a number of requested flows caused by their undetermined routing paths where only flow bandwidth is considered in path determination. This paper proposes a Quality-of-Service (QoS) based Flow Assignment algorithm which enables the computation of end-to-end path for traffic flows guaranteeing the QoS requirements including bandwidth, end-to-end delay and packet loss probability. Through the Open Source Hybrid IP/SDNs platform, the proposed algorithm is validated and shown to significantly reduce flow rejection rate of up to 50% compared to the conventional approach, and therefore can be used to implement an effective DiffServ mechanism for flow allocation in the SDNs
Y-Comm: a global architecture for heterogeneous networking.
In the near future mobile devices with several interfaces will become commonplace. Most of the peripheral networks using the Internet will therefore employ wireless technology. To provide support for these devices, this paper proposes a new framework which encompasses the functions of both peripheral and core networks.
The framework is called Y-Comm and is defined in a layered
manner like the OSI model
A formally verified AKA protocol for vertical handover in heterogeneous environments using Casper/FDR
Next generation networks will comprise different wireless networks including cellular technologies, WLAN and indoor technologies. To support these heterogeneous environments, there is a need to consider a new design of the network infrastructure. Furthermore, this heterogeneous environment implies that future devices will need to roam between different networks using vertical handover techniques. When a mobile user moves into a new foreign network, data confidentiality and mutual authentication between the user and the network are vital issues in this heterogeneous environment. This article deals with these issues by first examining the implication of moving towards an open architecture, and then looking at how current approaches such as the 3GPP, HOKEY and mobile ethernet respond to the new environment while trying to address the security issue. The results indicate that a new authentication and key agreement protocol is required to secure handover in this environment. Casper/FDR, is used in the analysis and development of the protocol. The proposed protocol has been proven to be
successful in this heterogeneous environment
Enabling seamless V2I communications towards developing cooperative automotive applications in VANET systems
Cooperative applications for VANET will require seamless communication between Vehicle to Infrastructure and Vehicle to Vehicle. IEEE 802.11p has been developed to facilitate this effort. However, in order to have seamless communication for these applications, it is necessary to look at handover as vehicles move between Road-side Units. Traditional models of handover used in normal mobile environments are unable to cope with the high velocity of the vehicle and the relatively small area of coverage with regard to vehicular environments. The YComm framework has yielded techniques to calculate the Time Before Vertical Handover and the Network Dwell Time for any given network topology. Furthermore, by knowing these two parameters, it is also possible to improve channel allocation and resource management in network infrastructure such as base-stations, relays, etc. In this article we explain our overall approach by describing the VANET Testbed and show that in Vehicular environments it is necessary to consider a new handover model which is based on a probabilistic rather than a fixed coverage approach. Finally, we show a new performance model for proactive handover which is then compared with traditional approaches
Exploring the provision of reliable network storage in highly mobile environments
Computing is fundamentally about processing data which must be readily accessible to processing elements. Hence, the use of storage hierarchies plays an important role in the overall performance of computer systems. Recently, due to the deployment of fast networks, network storage has emerged as a viable alternative to large local storage systems. However, trying to provide reliable network storage in highly mobile environments, such as vehicular networks, results in the need to address several issues. This paper explores these challenges by first looking at the communication dynamics required for seamless connectivity in these networks. It then looks at how services can be migrated as users move around. The results of this analysis are applied to the migration of a simple Network Memory Server using different migration techniques such as Docker, KVM, LXD and Unikernels in an edge environment, represented by a real Vehicle Ad-Hoc Network. The results show that a proactive approach to service migration is needed to support such services in highly mobile environments
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