1,738,621 research outputs found
Medium access control, error control and routing in underwater acoustic networks: a discussion on protocol design and implementation
Full text linkThe journey of underwater communication which began from Leonardo’s era took four and a half centuries to find practical applications for military purposes during World War II. However, over the last three decades, underwater acoustic communications witnessed a massive development due to the advancements in the design of underwater communicating
peripherals and their supporting protocols. Successively, doors are opened for a wide range of applications to employ in the underwater environment, such as oceanography, pollution
monitoring, offshore exploration, disaster prevention, navigation assistance, monitoring, coastal patrol and surveillance. Different applications may have different characteristics and hence, may require different network architectures. For instance, routing protocols designed for unpartitioned multi-hop networks are not suitable for Delay-Tolerant Networks. Furthermore, single-hop networks do not need routing protocols at all. Therefore, before
developing a protocol one must study the network architecture properly and design it accordingly.
There are several other factors which should also be considered with the network architecture while designing an efficient protocol for underwater networks, such as long propagation delay, limited bandwidth, limited battery power, high bit error rate of the channel and several other adverse properties of the channel, such as, multi-path, fading and refractive behaviors. Moreover, the environment also has an impact on the performance of the protocols designed for underwater networks. Even temperature changes in a single day have an impact on the performance of the protocols. A good protocol designed for any network should consider some or all of these characteristics to achieve better performance.
In this thesis, we first discuss the impact of the environment on the performance of MAC and routing protocols. From our investigation, we discover that even temperature changes within a day may affect the sound speed profile and hence, the channel changes and the protocol performance vary. After that we discuss several protocols which are specifically designed for underwater acoustic networks to serve different purposes and for different network architectures. Underwater Selective Repeat (USR) is an error control protocol designed to assure reliable data transmission in the MAC layer. One may suspect that employing an error control technique over a channel which already suffers from long propagation delays is a burden. However, USR utilizes long propagation by transmitting multiple packets in a single RTT using an interlacing technique. After USR, a routing protocol for surveillance networks is discussed where some sensors are laid down at the bottom of the sea and some sinks are placed outside the area. If a sensor detects an asset within its detection range, it announces the presence of intruders by transmitting packets to the sinks. It may happen
that the discovered asset is an enemy ship or an enemy submarine which creates noise to jam the network. Therefore, in surveillance networks, it is necessary that the protocols have
jamming resistance capabilities. Moreover, since the network supports multiple sinks with similar anycast address, we propose a Jamming Resistance multi-path Multi-Sink Routing
Protocol (MSRP) using a source routing technique. However, the problem of source routing is that it suffers from large overhead (every packet includes the whole path information) with
respect to other routing techniques, and also suffers from the unidirectional link problem. Therefore, another routing protocol based on a distance vector technique, called Multi-path
Routing with Limited Cross-Path Interference (L-CROP) protocol is proposed, which employs a neighbor-aware multi-path discovery algorithm to support low interference multiple paths
between each source-destination pair. Following that, another routing protocol is discussed for next generation coastal patrol and surveillance network, called Underwater Delay-Tolerant
Network (UDTN) routing where some AUVs carry out the patrolling work of a given area and report to a shore based control-center. Since the area to be patrolled is large, AUVs
experience intermittent connectivity. In our proposed protocol, two nodes that understand to be in contact with each other calculate and divide their contact duration equally so that
every node gets a fair share of the contact duration to exchange data. Moreover, a probabilistic spray technique is employed to restrict the number of packet transmissions and for error correction a modified version of USR is employed.
In the appendix, we discuss a framework which was designed by our research group to realize underwater communication through simulation which is used in most of the simulations in this thesis, called DESERT Underwater (short for DEsign, Simulate, Emulate and Realize Test-beds for Underwater network protocols). It is an underwater extension of the
NS-Miracle simulator to support the design and implementation of underwater network protocols. Its creation assists the researchers in to utilizing the same codes designed for the
simulator to employ in actual hardware devices and test in the real underwater scenario
REDD+ and mangroves : a study on Sundarbans
No full textSundarbans, a Ramsar and World Heritage site, is the largest single block of tidal halophytic mangrove forest in the world covering parts of Bangladesh and India. Natural mangroves were very common along the entire coast of Bangladesh. However, all other natural mangrove forests, including the Chakaria Sundarbans with 21,000 hectares of mangrove, have been cleared for shrimp cultivation. Against this backdrop, the Forest Department of Bangladesh has developed project design documents for a project called ‘Collaborative REDD+ Improved Forest Management (IFM) Sundarbans Project’ (CRISP) to save the only remaining natural mangrove forest of the country. This project, involving conservation of 412,000 ha of natural mangrove forests, is expected to generate, over a 30-year period, a total emissions reduction of about 6.4 million tons of CO2. However, the successful implementation of this project involves a number of critical legal and institutional issues. It may involve complex legal issues such as forest ownership, forest use rights, rights of local people and carbon rights. It may also involve institutional reforms. Ensuring good governance of the proposed project is very vital considering the failure of the Asian Development Bank (ADB) funded and Bangladesh Forest Department managed ‘Sundarbans Biodiversity Conservation Project’. Considering this previous experience, this paper suggests that a comprehensive legal and institutional review and reform is needed for the successful implementation of the proposed CRISP project. This paper argues that without ensuring local people’s rights and their participation, no project can be successful in the Sundarbans. Moreover, corruption of local and international officials may be a serious hurdle in the successful implementation of the project
Agroforestry and sustainable livelihoods in Vanuatu: insights from two case studies
No full textThis paper provides a brief overview of agroforestry systems in Vanuatu through case studies on two villages on Efate Island, Etas and Epau. Epau village is longer settled and is characterised by secure property rights, while Etas is a newly settled village with less secure property rights. Common problems facing both villages relate to access to markets and technology, and lack of storage facilities for agricultural produce. These limit farm productivity and profitability, and undermine sustainable livelihoods in both villages. The findings indicate the need to provide an enabling environment for the farming communities by ensuring easier access to markets and technology. This calls for strengthening the agricultural research and development and extension services and stronger marketing agencies. Livelihoods in the village with less secure property rights appear less sustainable
Agroforestry and sustainable livelihoods in Fiji: Two case studies
No full textThis paper reports two case studies on agriculture and agroforestry systems in two contrasting farming settlements on the island of Viti Levu, Fiji. The settlements differ in terms of cropping systems and land tenure regimes. In one settlement farmers’ livelihoods are based on diversified cropping systems including agroforestry, while in the other farmers have sugarcane-based farming systems. One settlement is characterised by secure property rights while the other has less secure property rights. Common problems facing both villages relate to access to markets and improved technology, obtaining fair prices for agricultural produce, high transportation cost, vulnerability to natural disasters, and poor access to credit and research and extension services. Problems specific to the sugarcane-based farming systems relate to land tenure insecurity, non-availability of farm workers during harvesting season and lack of labour-saving technology. It is argued that support is needed for the farming communities in terms of ensuring easier access to product markets and storage, access to improved technology including mechanisation, creating a more secure land tenure regime, increased research and extension services, and affordable transportation services. The policy response may involve consolidation of holdings so that bigger farms can employ mechanical technology more efficiently for sugarcane cultivation. Smaller farmers currently growing sugarcane require support to diversify their farming activities and grow other crops such as vegetables, fruit and staples
Policies and laws for promoting sustainable agroforestry in Vanuatu
No full textAn appropriate legal and policy framework is important for the development of agroforestry. This paper identifies and discusses some of the key legal and policy issues arising with respect to Vanuatu’s move to develop sustainable agroforestry. Fundamentally, there is a lack of a joint agroforestry strategy for relevant government departments, and this challenges the effectiveness of existing policies that touch upon agroforestry, particularly those relating to agriculture and forestry. There is a significant overlap of agroforestry-related activities across several government departments, and coordination and cooperation between these departments is wanting. Finally, alienation of local communities from their land is a major hurdle for agroforestry development in Vanuatu. This paper suggests that the government should take immediate initiatives for management of agriculture leases, particularly regarding lease to foreigners; and support for interagency cooperation is needed for promotion of agroforestry
Non-market values of agroforestry systems and implications for Pacific island agroforestry
No full textIn general, financial analysis of forestry and agroforestry investments does not take into account the broader social, environmental, cultural, traditional and other benefits of these systems. Hence, this paper examines methods of estimating non-market values to provide policy support. Such values would have relevance with respect to carbon sequestration, sea-level rise, watershed protection, preserving mangrove areas and coastal fisheries, improving the supply of healthy food products to improve public health, and in general, a wide range of policy areas. Under social cost–benefit analysis, if the overall benefits—private, social and environmental—are found to exceed the costs (or the benefit-to-cost ratio is greater than 1.0), a project is considered to be justified on economic grounds. Because some important benefits are not reflected in market transactions, various methods have been developed to estimate values of non-market goods and services. \ud
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Among the better known methods are: travel cost method(TCM) for valuing recreation benefits; contingent valuation method (CVM) for estimating consumer willingingness to pay (WTP) for a wide package of benefits; and environmental choice modelling, which breaks WTP down into a number of components. The hedonic price method (HPM) is used to estimate values associated with market transactions, such as the values of attractive landscapes, low noise and proximity to public transport, with these estimated by their impact on property prices (i.e. as revealed rather than just stated preferences). In practice, the benefit transfer method (utilising values adopted from previous research rather than conducting new and costly evaluation efforts) is often used as a convenient expedient for non-market values. Many databases of environmental values have been developed, which allow values from a source site to be inferred for a target site. The importance of watershed protection or remediation is well recognised in Fiji and Vanuatu. Flooding is often associated with cyclones and can have serious impacts on tourism, cropping areas and watercourses. Various Pacific island tree species have wide-spreading root systems and are well suited for stream bank and coastal land stabilisation. Revegetation of these areas can have considerable non-market benefits. Estimation of values of such benefits—say by CVM or benefit transfer—could be used to place dollar values on riparian and coastal tree plantings and to guide government policy as to whether such investment would be justified on broad socio-economic grounds
Maritime Terrorism and the Role of Judicial Institutions in the International Legal Order
No full textIn Maritime Terrorism and the Role of Judicial Institutions in the International Legal Order, Md Saiful Karim offers a critical analysis of the role of judicial institutions in combating maritime terrorism. This book comprehensively examines the existing international legal framework for combating maritime terrorism and argues for a an updated framework to tackle modern threats. In particular, Karim highlights the important task of national courts in the prosecution of suspected maritime terrorists as well as the settlement of disputes arising from maritime terrorism. It fills in important gaps in the existing literature and proposes a path for the influence of international juridical institutions
Kumpulan makalah pelatihan instrukture klinik keperawatan/ Akper. RSUD. Dr. Saiful Anwar
No full textHal. Tak beraturan: tab; 28 c
Policy and legal framework for promoting sustainable agroforestry in Fiji
No full textThis paper critically examines the key legal and policy issues in developing sustainable agroforestry on unproductive land in Viti Levu, Fiji. Much of this land has become unproductive because of the decline in Fiji’s sugar industry, on which the country has long relied. Interest in other land uses has thus arisen. Recent reports indicate that only a very minimal amount of agroforestry is being practised in Fiji, and it is pertinent to examine the opportunities and constraints facing the promotion of sustainable agroforestry development. This paper presents an overview of existing laws and policies in Fiji relevant to agroforestry and provides some policy recommendations for promotion of agroforestry. It appears that, although there is strong support for agroforestry in agricultural and forestry polices, practical efforts and the coordination for implementation of the broader policy objectives are lacking
Principles of Entrepreneurship (ENT530): Social Media Portfolio: Cookies Crunch / Nurul Syazwani Saiful Bahari
Full text linkCookies Crunch is a small business that has to introduce by myself. I plan the businesses through an online platform for advertising and selling. My products are more focused on quality to the customer. The admin for the online business is me named, Nurul Syazwani Binti Saiful Bahari. We cover up cash on delivery in Kuantan, Pahang area while the others we sent through shipping. Cookies Crunch offers to the customer crunchy and soft cookies for the sweet tooth and cookies lover. Our target market is individuals who love cookies range age from kids to elderly. What the best is, our taste feels like which makes the customer satisfied. at the end of the summary, I hope my small business will grow and expend more further in the future and more and we will provide a lot of delicious flavours that can satisfy more customer
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