Minimum energy wireless sensor networks

PhD programme overviewHere, on-off keying modulation is used as a means of reducing the transmit energy requirements whilst exploiting inherent channel coding, which sets the scene of this PhD study

An improved switching hybrid recommender system using naive Bayes classifier and collaborative filtering

Recommender Systems apply machine learning and data mining techniques for filtering unseen information and can predict whether a user would like a given resource. To date a number of recommendation algorithms have been proposed, where collaborative filtering and content-based filtering are the two most famous and adopted recommendation techniques. Collaborative filtering recommender systems recommend items by identifying other users with similar taste and use their opinions for recommendation; whereas content-based recommender systems recommend items based on the content information of the items. These systems suffer from scalability, data sparsity, over specialization, and cold-start problems resulting in poor quality recommendations and reduced coverage. Hybrid recommender systems combine individual systems to avoid certain aforementioned limitations of these systems. In this paper, we proposed a unique switching hybrid recommendation approach by combining a Naive Bayes classification approach with the collaborative filtering. Experimental results on two different data sets, show that the proposed algorithm is scalable and provide better performance – in terms of accuracy and coverage – than other algorithms while at the same time eliminates some recorded problems with the recommender systems

Laser surface cladding/particle injection of wear resistant alloys and composites

Imperial Users onl

Possibility of observing charged Higgs in the single top production via its τ\tau lepton decay at LHC

Single top quark production through weak interactions is considered to be an important source of charged Higgs in the Minimal Super Symmetric Standard Model. In the s-channel single top production having largest cross-section may appear as a propagator in the form of heavy resonance state decaying to a pair of top and bottom quark. The process under investigation is $pp \rightarrow H^{\pm}\rightarrow tb \rightarrow b\bar{b}W^{\pm} \rightarrow b\bar{b}\tau^{\pm} \nu_{\tau}$, where top quark exclusively decays into a pair of bottom quark and W boson while W boson subsequently decays to $\tau$ jet and neutrino. So the final state is characterized by the presence of two b jets, hadronic $\tau$ decay and missing transverse energy. Within the presence of QCD multijet and electroweak background events at LHC, it has been demonstrated that the charged Higgs signal observability is possible within the available MSSM parameter space (tan$\beta$, $m_{H^{\pm}})$ respecting all experimental and theoretical constraints. In order to show the observability potential of charged Higgs, the exclusion curves at 95$\%$ confidence level and 5$\sigma$ contours are plotted at different integrated luminosities with $\sqrt{s}=$14 TeV.Comment: arXiv admin note: substantial text overlap with arXiv:1711.0834

Performance analysis of a novel decentralised MAC protocol for cognitive radio networks

Due to the demand of emerging Cognitive Radio (CR) technology to permits using the unused licensed spectrum parts by cognitive users (CUs) to provide opportunistic and efficient utilisation of the white spaces. This requires deploying a CR MAC with the required characteristics to coordinate the spectrum access among CUs. Therefore, this paper presents the design and implementation of a novel Medium Access Control (MAC) protocol for decentralised CRNs (MCRN). The protocol provides efficient utilisations of the unused licensed channels and enables CUs to exchange data successfully over licensed channels. This is based on the observation procedure of sensing the status of the Licensed Users (LUs) are ON or OFF over the licensed channels. The protocol is validated with the comparison procedure against two different benchmark protocols in terms of the network performance; communication time and throughput. Therefore, performance analysis demonstrated that the proposed MCRN perform better and achieve higher throughput and time benefits than the benchmarks protocols

Spectrum sharing security and attacks in CRNs: a review

Cognitive Radio plays a major part in communication technology by resolving the shortage of the spectrum through usage of dynamic spectrum access and artificial intelligence characteristics. The element of spectrum sharing in cognitive radio is a fundament al approach in utilising free channels. Cooperatively communicating cognitive radio devices use the common control channel of the cognitive radio medium access control to achieve spectrum sharing. Thus, the common control channel and consequently spectrum sharing security are vital to ensuring security in the subsequent data communication among cognitive radio nodes. In addition to well known security problems in wireless networks, cognitive radio networks introduce new classes of security threats and challenges, such as licensed user emulation attacks in spectrum sensing and misbehaviours in the common control channel transactions, which degrade the overall network operation and performance. This review paper briefly presents the known threats and attacks in wireless networks before it looks into the concept of cognitive radio and its main functionality. The paper then mainly focuses on spectrum sharing security and its related challenges. Since spectrum sharing is enabled through usage of the common control channel, more attention is paid to the security of the common control channel by looking into its security threats as well as protection and detection mechanisms. Finally, the pros and cons as well as the comparisons of different CR - specific security mechanisms are presented with some open research issues and challenges

DDH-MAC: a novel dynamic de-centralized hybrid MAC protocol for cognitive radio networks

The radio spectrum (3kHz - 300GHz) has become saturated and proven to be insufficient to address the proliferation of new wireless applications. Cognitive Radio Technology which is an opportunistic network and is equipped with fully programmable wireless devices that empowers the network by OODA cycle and then make intelligent decisions by adapting their MAC and physical layer characteristics such as waveform, has appeared to be the only solution for current low spectrum availability and under utilization problem. In this paper a novel Dynamic De-Centralized Hybrid “DDH-MAC” protocol for Cognitive Radio Networks has been presented which lies between Global Common Control Channel (GCCC) and non-GCCC categories of cognitive radio MAC protocols. DDH-MAC is equipped with the best features of GCCC MAC protocols but also overcomes the saturation and security issues in GCCC. To the best of authors' knowledge, DDH-MAC is the first protocol which is hybrid between GCCC and non-GCCC family of protocols. DDH-MAC provides multiple levels of security and partially use GCCC to transmit beacon which sets and announces local control channel for exchange of free channel list (FCL) sensed by the co-operatively communicating cognitive radio nodes, subsequently providing secure transactions among participating nodes over the decided local control channel. This paper describes the framework of the DDH-MAC protocol in addition to its pseudo code for implementation; it is shown that the pre-transmission time for DDH-MAC is on average 20% better while compared to other cognitive radio MAC protocols

A survey of QoS-aware web service composition techniques

Web service composition can be briefly described as the process of aggregating services with disparate functionalities into a new composite service in order to meet increasingly complex needs of users. Service composition process has been accurate on dealing with services having disparate functionalities, however, over the years the number of web services in particular that exhibit similar functionalities and varying Quality of Service (QoS) has significantly increased. As such, the problem becomes how to select appropriate web services such that the QoS of the resulting composite service is maximized or, in some cases, minimized. This constitutes an NP-hard problem as it is complicated and difficult to solve. In this paper, a discussion of concepts of web service composition and a holistic review of current service composition techniques proposed in literature is presented. Our review spans several publications in the field that can serve as a road map for future research

BIOINFORMATIC ANALYSIS OF A MAMMALIAN BIP GENE FOR INSERTION INTO GREEN ALGAE AND COMPARISON OF ITS POSSIBLE EFFECTS ON THE SYNTHESIS OF A MAMMALIAN ANTIBODY

This dissertation describes a study utilizing bioinformatics to analyze homologues of a molecular chaperone, glucose-regulated protein 78 (grp 78), also known as BiP. The selected homologous proteins originate from organisms of infinitely diverse genera. Comparisons of protein sequence yielded the first clues of a common ancestry among these proteins. Furthermore, protein molecular weights, isoelectric points, N-terminal amino acids and half-lives of a known homolog and a non-homologous protein were examined. Additionally, electroporation, a state-of-the-art plasmid insertion technique, was explored using Chlamydomonas reinhardtii, a green alga, as the recipient of a parent plasmid, pSP124S. Distinctive hypertonic solutions and three separate field strengths were used in the plasmolysis of the cell wall of C. reinhardtii and subsequent electroporation, respectively. The number of transformants was tallied to evaluate which electroporation condition would yield the most transformed colonies. We had two discrete hypotheses: 1) that a structurally and functionally similar protein to glucose-regulated protein 78 exists across a wide spectrum of organisms and 2) that Chlamydomonas reinhardtii could be successfully transformed with pSP124S under certain electroporation conditions. The bioinformatics investigation revealed that analogous proteins to Human GRP 78 existed in Mus musculus (mouse), Rattus norvegicus (rat), Gallus domesticus (chicken), Gallus domesticus (chicken), Mesocricetus auratus (golden hamster), Bos taurus (cow), Xenopus laevis (frog), and Spinacia oleracea (spinach). Moreover, these homologous proteins more likely have a common evolutionary origin