4,979 research outputs found

    Analytical modelling of the effect of noise on the terahertz in-vivo communication channel for body-centric nano-networks

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    The paper presents an analytical model of the terahertz (THz) communication channel (0.1 - 10 THz) for in-vivo nano-networks by considering the effect of noise on link quality and information rate. The molecular absorption noise model for in-vivo nano-networks is developed based on the physical mechanisms of the noise present in the medium, which takes into account both the radiation of the medium and the molecular absorption from the transmitted signal. The signal-to-noise ratio (SNR) of the communication channel is investigated for different power allocation schemes and the maximum achievable information rate is studied to explore the potential of THz communication inside the human body. The obtained results show that the information rate is inversely proportional to the transmission distance. Based on the studies on channel performance, it can be concluded that the achievable transmission distance of in-vivo THz nano-networks should be restrained to approximately 2 mm maximum, while the operation band of in-vivo THz nano-networks should be limited to the lower band of the THz band. This motivates the utilisation of hierarchical/cooperative networking concepts and hybrid communication techniques using molecular and electromagnetic methods for future body-centric nano-networks

    Experimentally estimated dead space for GaAs and InP based planar Gunn diodes

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    The authors would like to thank the staff of the James Watt Nanofabrication Centre at the University of Glasgow for help in fabricating the devices which is reported in this paper. ā€˜Part of this work was supported by ESPRC through EP/H011862/ 1, and EP/H012966/1.Peer reviewedPublisher PD

    Analytical characterisation of the terahertz in-vivo nano-network in the presence of interference based on TS-OOK communication scheme

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    The envisioned dense nano-network inside the human body at terahertz (THz) frequency suffers a communication performance degradation among nano-devices. The reason for this performance limitation is not only the path loss and molecular absorption noise, but also the presence of multi-user interference and the interference caused by utilising any communication scheme, such as time spread ONā€”OFF keying (TS-OOK). In this paper, an interference model utilising TS-OOK as a communication scheme of the THz communication channel inside the human body has been developed and the probability distribution of signal-to-interference-plus-noise ratio (SINR) for THz communication within different human tissues, such as blood, skin, and fat, has been analyzed and presented. In addition, this paper evaluates the performance degradation by investigating the mean values of SINR under different node densities in the area and the probabilities of transmitting pulses. It results in the conclusion that the interference restrains the achievable communication distance to approximate 1 mm, and more specific range depends on the particular transmission circumstance. Results presented in this paper also show that by controlling the pulse transmission probability and node density, the system performance can be ameliorated. In particular, SINR of in vivo THz communication between the deterministic targeted transmitter and the receiver with random interfering nodes in the medium improves about 10 dB, when the node density decreases one order. The SINR increases approximate 5 and 2 dB, when the pulse transmitting probability drops from 0.5 to 0.1 and 0.9 to 0.5

    Perbandingan Keanekaragaman Hymenoptera Parasitoid pada Agroekosistem Kedelai dengan Aplikasi dan tanpa Aplikasi Insektisida

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    Sistem pengelolaan tanaman kedelai dengan penggunaan insektisida sintetik yang intensif akan menurunkan keanekaragaman jenis Hymenoptera parasitoid. Penelitian bertujuan untuk memban-dingkan keanekaragaman Hymenoptera parasitoid pada agroekosistem kedelai dengan dan tanpa aplikasi insektisida sintetik. Pengumpulan data serangga menggunakan perangkap dari jaring serangga dan nampan kuning. Hasil penelitian menunjukkan bahwa indeks keanekaragaman jenis pada fase pertumbuhan vegetatif dan generatif kedelai dengan aplikasi insektisida lebih rendah dibandingkan dengan yang tanpa aplikasi insektisida, yang keduanya tergolong sedang. Indeks kemerataan jenis pada fase pertumbuhan vegetatif dan generatif dari kedua agroekosistem kedelai tergolong tinggi. Indeks kekayaan jenis pada fase vegetatif dari agroekosistem kedelai dengan aplikasi insektisida tergolong rendah (0<2,3955ā‰¤2,5), sedangkan pada fase generatif tergolong sedang (0<3,6118ā‰¤4). Indeks kekayaan jenis pada fase vegetatif (0<2,6229ā‰¤4) dan generatif (0<3,8287ā‰¤4) dari agroekosistem kedelai tanpa aplikasi insektisida tergolong sedang. Komunitas Hymenoptera parasitoid pada agroekosistem kedelai tanpa aplikasi insektisida memiliki kemiripan lebih rendah daripada yang dengan aplikasi insektisida. Aplikasi insektisida mempengaruhi indeks kekayaan jenis pada fase generatif dan kemiripan komunitasnya, yaitu nilainya lebih rendah daripada yang tanpa insektisida

    Moderate ischemic mitral regurgitation (IMR) and metabolic syndrome: where are we now and where are we going?

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    BACKGROUND: The metabolic syndrome appears to affect 10% to 25% of adult population worldwide. Several studies have described the association between metabolic syndrome and ischaemic heart disease, however, none linked metabolic syndrome to ischemic mitral regurgitation, a serious clinical problem facing both the cardiologists and cardiac surgeons. Ischemic mitral regurgitation is mitral insufficiency caused by myocardial infarction. The myocardial ischemia can result in altered ventricular geometry, leading to mitral insufficiency. Interestingly metabolic syndrome showed more pronounced alteration of left ventricular geometry and function especially in obese subjects. PRESENTATION OF THE HYPOTHESIS: We have recently proposed that there is link between metabolic syndrome and ischemic mitral regurgitation and associated complications. Operative strategy for moderate ischaemic mitral regurgitation continues to be debated between revascularisation alone and concomitant valve repair at the time of coronary artery bypass surgery. Each of the above group has published studies, with results supporting each argument. TESTING THE HYPOTHESIS: Generally speaking the treatments available for metabolic syndrome are based in both life style modification (dietary advice and advice to increase physical activity) and medical treatment to enhance insulin sensitivity. Randomised controlled trials may show whether the current available treatment of metabolic syndrome may have an impact on moderate ischemic mitral regurgitation. IMPLICATIONS OF THE HYPOTHESIS: Metabolic syndrome was shown to alter left ventricular geometry and therefore it is possible to postulate that the variation in the response of different patients with moderate ischemic mitral regurgitation to current management may be attributed to the absence and presence of metabolic syndrome. Research testing of this hypothesis in the future may reveal whether concomitant treatment of metabolic syndrome will play part in the management of moderate ischemic mitral regurgitation

    Efficient performative actions for e-commerce agents

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    The foundational features of multi-agent systems are communication and interaction with other agents. To achieve these features, agents have to transfer messages in the predefined format and semantics. The communication among these agents takes place with the help of ACL (Agent Communication Language). ACL is a predefined language for communication among agents that has been standardised by the FIPA (Foundation for Intelligent Physical Agent). FIPA-ACL defines different performatives for communication among the agents. These performatives are generic, and it becomes computationally expensive to use them for a specific domain like e-commerce. These performatives do not define the exact meaning of communication for any specific domain like e-commerce. In the present research, we introduced new performatives specifically for e-commerce domain. Our designed performatives are based on FIPA-ACL so that they can still support communication within diverse agent platforms. The proposed performatives are helpful in modelling e-commerce negotiation protocol applications using the paradigm of multi-agent systems for efficient communication. For exact semantic interpretation of the proposed performatives, we also performed formal modelling of these performatives using BNF. The primary objective of our research was to provide the negotiation facility to agents, working in an e-commerce domain, in a succinct way to reduce the number of negotiation messages, time consumption and network overhead on the platform. We used an e-commerce based bidding case study among agents to demonstrate the efficiency of our approach. The results showed that there was a lot of reduction in total time required for the bidding process

    Determination of training needs for water users associations in Gezira Scheme, Sudan

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    124 The main objective of the study was to determine the training needs for Water Users Associations (WUAs) in order to suggest appropriate training programs. Seven irrigation divisions were selected randomly from 21 irrigation divisions (Wad Elnaw,Wad Elbur, Tabat, Kab Elgidad,&nbsp; Shalaie, Wad Elmansi and Gaboja). &nbsp;A questionnaire was designed to collect the required data by using random sample technique from 395 farmers. The information was collected during the period from April to July 2010.The data were statistically analyzed using the statistical package for social science (SPSS) to calculate frequency, percentages, mean and standard deviation. A Likert scale was used to determine the needed level of training. The study revealed that the previous training courses, training content and duration were neither suitable nor sufficient, because the training courses were concise, short and irrelevant to farmers training needs. In addition, the study revealed that the vast majority of Gezira Scheme farmers preferred practical oriented methods (field demonstrations and field days) to encourage the WUAs to adopt new technology in the irrigation of fields to develop skills, upgrade knowledge and bring positive change among farmers. The study showed that most of farmers were not convinced with the WUAs performance, and that there is a strong need for regular and intensive training programs to raise WUAs capacity regarding management and proper use of irrigation water; rules and regulations; operation and maintenance of irrigation canals; water request and crops water requirement; and water management and water supply contract. All farmers need active participation in water charge, cost recovery and participation in crop choice. This participation must be based on planning of appropriate training programs that consider farmers training needs and&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; . &nbsp

    Application of ANN to Real and Reactive Power Allocation Scheme

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    This chapter describes the implementation of ANN for real and reactive power transfer allocation. The 25 bus equivalent power system of south Malaysia region and IEEE 118 bus system are used to demonstrate the applicability of the ANN output compared to that of the Modified Nodal Equations (MNE) which is used as trainers for real and reactive power allocation. The basic idea is to use supervised learning paradigm to train the ANN. Then the descriptions of inputs and outputs of the training data for the ANN are easily obtained from the load flow results and each method used as teachers respectively. The proposed ANN based method provides promising results in terms of accuracy and computation time. Artificial intelligence has been proven to be able to solve complex processes in deregulated power system such as loss allocation. So, it can be expected that the developed methodology will further contribute in improving the computation time of transmission usage allocation for deregulated system
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