Now showing items 672-690 of 690

• #### Validation of aerosol products from AATSR and MERIS/AATSR synergy algorithms—Part 1: Global Evaluation.

The European Space Agency’s (ESA’s) Aerosol Climate Change Initiative (CCI) project intends to exploit the robust, long-term, global aerosol optical thickness (AOT) dataset from Europe’s satellite observations. Newly released Swansea University (SU) aerosol products include AATSR retrieval and synergy between AATSR and MERIS with a spatial resolution of 10 km. In this study, both AATSR retrieval (SU/AATSR) and AATSR/MERIS synergy retrieval (SU/synergy) products are validated globally using Aerosol Robotic Network (AERONET) observations for March, June, September, and December 2008, as suggested by the Aerosol-CCI project. The analysis includes the impacts of cloud screening, surface parameterization, and aerosol type selections for two products under different surface and atmospheric conditions. The comparison between SU/AATSR and SU/synergy shows very accurate and consistent global patterns. The global evaluation using AERONET shows that the SU/AATSR product exhibits slightly better agreement with AERONET than the SU/synergy product. SU/synergy retrieval overestimates AOT for all surface and aerosol conditions. SU/AATSR data is much more stable and has better quality; it slightly underestimates fine-mode dominated and absorbing AOTs yet slightly overestimates coarse-mode dominated and non-absorbing AOTs.
• #### A validation of security determinants model for cloud adoption in Saudi organisations’ context

Governments across the world are starting to make a dynamic shift to cloud computing so as to increase efficiency. Although, the cloud technology brings various benefits for government organisations, including flexibility and low cost, adopting it with the existing system is not an easy task. In this regard, the most significant challenge to any government agency is security concern. Our previous study focused to identify security factors that influence decision of government organisations to adopt cloud. This research enhances the previous work by investigating on the impact of various independent security related factors on the adopted security taxonomy based on critical ratio, standard error and significance levels. Data was collected from IT and security experts in the government organisations of Saudi Arabia. The Analysis of Moment Structures (AMOS) tool was used in this research for data analysis. Critical ratio reveals the importance of Security Benefits, Risks and Awareness Taxonomies on cloud adoption. Also, most of the exogenous variables had strong and positive relationships with their fellow exogenous variables. In future, this taxonomy model can also be applied for studying the adoption of new IT innovations whose IT architecture is similar to that of the cloud.
• #### Vehicular cloud networks: Architecture and security

Cloud computing has been widely adopted across the IT industry due to its scalable, cost-effective, and efficient services. It has many applications in areas such as healthcare, mobile cloud computing (MCC), and vehicular ad hoc networks (VANET). Vehicular cloud networks (VCN) is another application of cloud computing which is a combination of cloud and VANET technologies. It is composed of three clouds named vehicular cloud, infrastructure cloud, and traditional IT cloud. In this chapter, the three clouds involved in VCN are presented using a three-tier architecture, and the security issues related to each tier are described in detail. After describing the detailed architecture of VANET, their components, and their important characteristics, this chapter presents the architecture of VCN. It is followed by the detailed analysis of the threats to which each tier-cloud of VCN is vulnerable.
• #### Vehicular cloud networks: Architecture, applications and security issues

Vehicular Ad Hoc Networks (VANET) are the largest real life application of ad-hoc networks where nodes are represented via fast moving vehicles. This paper introduces the future emerging technology, i.e., Vehicular Cloud Networking (VCN) where vehicles and adjacent infrastructure merge with traditional internet clouds to offer different applications ranging from low sized applications to very complex applications. VCN is composed of three types of clouds: Vehicular cloud, Infrastructure cloud and traditional Back-End (IT) cloud. We introduced these clouds via a three tier architecture along with their operations and characteristics. We have proposed use cases of each cloud tier that explain how it is practically created and utilised while taking the vehicular mobility in consideration. Moreover, it is critical to ensure security, privacy and trust of VCN network and its assets. Therefore, to describe the security of VCN, we have provided an in-depth analysis of different threats related to each tier of VCN. The threats related to vehicular cloud and infrastructure cloud are categorized according to their assets, i.e., vehicles, adjacent infrastructure, wireless communication, vehicular messages, and vehicular cloud threats. Similarly, the Back-End cloud threats are categorized into data and network threats. The possible implications of these threats and their effects on various components of VCN are also explained in detail.
• #### Vehicular sensor networks: Applications, advances and challenges

Vehicular sensor networks (VSN) provide a new paradigm for transportation technology and demonstrate massive potential to improve the transportation environment due to the unlimited power supply of the vehicles and resulting minimum energy constraints. This special issue is focused on the recent developments within the vehicular networks and vehicular sensor networks domain. The papers included in this Special Issue (SI) provide useful insights to the implementation, modelling, and integration of novel technologies, including blockchain, named data networking, and 5G, to name a few, within vehicular networks and VSN.
• #### Verifiable public key encryption scheme with equality test in 5G networks

The emergence of 5G networks will allow Cloud Computing providers to offer more convenient services. However, security and privacy issues of cloud services in 5G networks represent huge challenges. Recently, to improve security and privacy, a novel primitive was proposed by Ma et al. in TIFS 2015, called Public Key Encryption with Equality Test supporting Flexible Authorization (PKEET-FA). However, the PKEET scheme lacks verification for equality test results to check whether the cloud performed honestly. In this research, we expand the study of PKEET-FA and propose a verifiable PKEET scheme, called V-PKEET, which, to the best of our knowledge, is the first work that achieves verification in PKEET. Moreover, V-PKEET has been designed for three types of authorization to dynamically protect the privacy of data owners. Therefore, it further strengthens security and privacy in 5G networks.
• #### Video authentication based on statistical local information

With the outgrowth of video editing tools, video information trustworthiness becomes a hypersensitive field. Today many devices have the capability of capturing digital videos such as CCTV, digital cameras and mobile phones and these videos may transmitted over the Internet or any other non secure channel. As digital video can be used to as supporting evidence, it has to be protected against manipulation or tampering. As most video authentication techniques are based on watermarking and digital signatures, these techniques are effectively used in copyright purposes but difficult to implement in other cases such as video surveillance or in videos captured by consumer’s cameras. In this paper we propose an intelligent technique for video authentication which uses the video local information which makes it useful for real world applications. The proposed algorithm relies on the video’s statistical local information which was applied on a dataset of videos captured by a range of consumer video cameras. The results show that the proposed algorithm has potential to be a reliable intelligent technique in digital video authentication without the need to use for SVM classifier which makes it faster and less computationally expensive in comparing with other intelligent techniques.
• #### Video stream analysis in clouds: An object detection and classification framework for high performance video analytics

Email Print Request Permissions Object detection and classification are the basic tasks in video analytics and become the starting point for other complex applications. Traditional video analytics approaches are manual and time consuming. These are subjective due to the very involvement of human factor. We present a cloud based video analytics framework for scalable and robust analysis of video streams. The framework empowers an operator by automating the object detection and classification process from recorded video streams. An operator only specifies an analysis criteria and duration of video streams to analyse. The streams are then fetched from a cloud storage, decoded and analysed on the cloud. The framework executes compute intensive parts of the analysis to GPU powered servers in the cloud. Vehicle and face detection are presented as two case studies for evaluating the framework, with one month of data and a 15 node cloud. The framework reliably performed object detection and classification on the data, comprising of 21,600 video streams and 175 GB in size, in 6.52 hours. The GPU enabled deployment of the framework took 3 hours to perform analysis on the same number of video streams, thus making it at least twice as fast than the cloud deployment without GPUs.
• #### Virtual vignettes: the acquisition, analysis, and presentation of social network data

Online social networks (OSNs) are immensely prevalent and have now become a ubiquitous and important part of the modern, developed society. However, online social networks pose significant problems to digital forensic investigators who have no experience online. Data will reside on multiples of servers in multiple countries, across multiple jurisdictions. Capturing it before it is overwritten or deleted is a known problem, mirrored in other cloud based services. In this article, a novel method has been developed for the extraction, analysis, visualization, and comparison of snapshotted user profile data from the online social network Twitter. The research follows a process of design, implementation, simulation, and experimentation. Source code of the tool that was developed to facilitate data extraction has been made available on the Internet.
• #### Well-quasi-order for permutation graphs omitting a path and a clique

We consider well-quasi-order for classes of permutation graphs which omit both a path and a clique. Our principle result is that the class of permutation graphs omitting P5 and a clique of any size is well-quasi-ordered. This is proved by giving a structural decomposition of the corresponding permutations. We also exhibit three infinite antichains to show that the classes of permutation graphs omitting {P6,K6}, {P7,K5}, and {P8,K4} are not well-quasi-ordered.
• #### WFS and HOA: Simulations and evaluations of planar higher order ambisonic, wave field synthesis and surround hybrid algorithms for lateral spatial reproduction in theatre.

Wave Field Synthesis and Higher Order Ambisonics are both spatialisation techniques that could be applied to theatre sound design, but practicalities such as the number of loudspeakers and space required limit their use. Practical setups could consist of a planar array across the stage (for performer localisation) and surround speakers around the auditorium in different configurations (for ambience). This research simulates the use of extrapolated and truncated arrays, with HOA and WFS algorithms in order to create a panned frontal dominant system with potentially increased intelligibility due to source separation and spatial unmasking. Hybrid methods where WFS and ambisonics are used simultaneously will be evaluated to create a system for theatre that is both psychoacoustically sound, homogenous and practicable.
• #### WHAM - Webcam Head-tracked AMbisonics

This paper describes the development and implementation of a real-time head-tracked auralisation platform using Higher Order Ambisonics (HOA) decoded binaurally based on open-source and freely available web technologies without the need for specialist head-tracking hardware. An example implementation of this work can be found at https://brucewiggins.co.uk/WHAM/.

• #### Who are you today? Profiling the ID theft fraudster

Online Identity Theft (ID theft) is a significant problem in our modern knowledge-based and social driven computing era. This type of cybercrime can be achieved in a number of different ways; and more of the point, various statistical figures suggest it is on the increase. The target is individual privacy and self-assurance, while efforts and measures for increased security and protection appear inadequate to prevent it. While personal identities are increasingly being stored and shared on digital media in virtualised environments, the threat of personal and private information that is used fraudulently cannot be eliminated. This trend in crime can result in complex investigations that involve virtualised information technologies, both as a medium for analysis and as evidence at the same time. Fraudsters are obtaining more sophisticated technological ways and increase their capability not only for committing but also for concealing their crimes. It is believed that fraudsters of this kind of crime are not acting individually, but rather they operate in an organised and well-structured manner. Indeed ID theft is nowadays directly linked to drug trafficking, money laundering and terrorism. ID theft, like almost all different types of crime, involves two parts, at least one victim and at least one fraudster. We argue that the differentiation of the investigation procedure between the victim’s and the fraudster’s side, depends on the ownership and control of the digital media involved in the crime, and can provide results on a more crime-focused basis. In addition it provides information gathering, understanding and knowledge about the way the fraudster acts and could potentially assist in future investigations. Different pieces of evidence can be discovered on each side (victim-fraudster) concerning the techniques that have been used to perpetrate the crime. The online ID theft techniques can leave evidence on both the victim’s and the fraudster’s system. However, the evidence tends to contain different elements on each side that can reveal information about the fraudster and eventually profile him in relation to the attack. There is an approach of profiling the ID theft fraudster based on the findings thatarise during the forensic investigation process in this paper. We discuss the extent of ID theft as a problem and the role of the fraudster in different ID theft techniques. We aim to demonstrate processes that could assist the profiling of the fraudster under the forensic investigation of ID theft.
• #### WiFi probes sniffing: an artificial intelligence based approach for MAC addresses de-randomization

To improve city services, local administrators need to have a deep understanding of how the citizens explore the city, use the relevant services, interact and move. This is a challenging task, which has triggered extensive research in the last decade, with major solutions that rely on analysing traces of network traffic generated by citizens WiFi devices. One major approach relies on catching the probe requests sent by devices during WiFi active scanning, which allows for counting the number of people in a given area and to analyse the permanence and return times. This approach has been a solid solution until some manufacturer introduced the MAC address randomization process to improve the user’s privacy, even if in some circumstances this seems to deteriorate network performance as well as the user experience. In this work we present a novel techniques to tackle the limitations introduced by the randomization procedures and that allows for extracting data useful for smart cities development. The proposed algorithm extracts the most relevant information elements within probe requests and apply clustering algorithms (such as DBSCAN and OPTICS) to discover the exact number of devices which are generating probe requests. Experimental results showed encouraging results with an accuracy of 65.2% and 91.3% using the DBSCAN and the OPTICS algorithms, respectively.
• #### A Wireless communication system for a quadrotor helicopter

The aim of this paper is to present real-time wireless communication between an AVR microcontroller and a quadcopter model built in Simulink representing a ground station. The wireless communication is achieved by using a pair of HC-05 Bluetooth modules. The wireless communication is performed on various controllers designed on Matlab/Simulink.
• #### Z-boson production in p-Pb collisions at $$\sqrt{s_{\mathrm{NN}}}$$ = 8.16 TeV and Pb-Pb collisions at $$\sqrt{s_{\mathrm{NN}}}$$ = 5.02 TeV

Measurement of Z-boson production in p-Pb collisions at √sNN = 8.16 TeV and Pb-Pb collisions at √sNN = 5.02 TeV is reported. It is performed in the dimuon decay channel, through the detection of muons with pseudorapidity −4 < ημ < −2.5 and transverse momentum pTμ > 20 GeV/c in the laboratory frame. The invariant yield and nuclear modification factor are measured for opposite-sign dimuons with invariant mass 60 < mμμ < 120 GeV/c2 and rapidity 2.5 < ycmsμμ< 4. They are presented as a function of rapidity and, for the Pb-Pb collisions, of centrality as well. The results are compared with theoretical calculations, both with and without nuclear modifications to the Parton Distribution Functions (PDFs). In p-Pb collisions the center-of-mass frame is boosted with respect to the laboratory frame, and the measurements cover the backward (−4.46 < ycmsμμ < −2.96) and forward (2.03 < ycmsμμ < 3.53) rapidity regions. For the p-Pb collisions, the results are consistent within experimental and theoretical uncertainties with calculations that include both free-nucleon and nuclear-modified PDFs. For the Pb-Pb collisions, a 3.4σ deviation is seen in the integrated yield between the data and calculations based on the free-nucleon PDFs, while good agreement is found once nuclear modifications are considered.
• #### ϒ suppression at forward rapidity in Pb–Pb collisions at √sNN=5.02TeV

Inclusive ϒ(1S) and ϒ(2S) production have been measured in Pb–Pb collisions at the centre-of-mass energy per nucleon–nucleon pair √sNN = 5.02 TeV, using the ALICE detector at the CERN LHC. The ϒ mesons are reconstructed in the centre-of-mass rapidity interval 2.5<y<4 and in the transverse-momentum range pT<15 GeV/c, via their decays to muon pairs. In this Letter, we present results on the inclusive ϒ(1S) nuclear modification factor RAA as a function of collision centrality, transverse momentum and rapidity. The ϒ(1S) and ϒ(2S) RAA, integrated over the centrality range 0–90%, are 0.37±0.02(stat)±0.03(syst) and 0.10±0.04(stat)±0.02(syst), respectively, leading to a ratio RAAϒ(2S)/RAAϒ(1S) of 0.28±0.12(stat)±0.06(syst). The observed ϒ(1S) suppression increases with the centrality of the collision and no significant variation is observed as a function of transverse momentum and rapidity.