Now showing items 695-704 of 704

• #### 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.