843 research outputs found

    Real Time Characterisation of the Mobile Multipath Channel

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    In this thesis a new approach for characterisation of digital mobile radio channels is investigated. The new approach is based on recognition of the fact that while the fading which is characteristic of the mobile radio channel is very rapid, the processes underlying this fading may vary much more slowly. The comparative stability of these underlying processes has not been exploited in system designs to date. ¶ Channel models are proposed which take account of the stability of the channel. Estimators for the parameters of the models are proposed, and their performance is analysed theoretically and by simulation and measurement. ¶ Bounds are derived for the extent to which the mobile channel can be predicted, and the critical factors which define these bounds are identified. ¶ Two main applications arise for these channel models. The first is the possibility of prediction of the overall system performance. This may be used to avoid channel fading (for instance by change of frequency), or compensate for it (by change of the signal rate or by power control). The second application is in channel equalisation. An equaliser based on a model which has parameters varying only very slowly can offer improved performance especially in the case of channels which appear to be varying so rapidly that the convergence rate of an equaliser based on the conventional model is not adequate. ¶ The first of these applications is explored, and a relationship is derived between the channel impulse response and the performance of a broadband system

    Matrix factorisations for the estimation of NMR relaxation distributions

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    The two most successful methods of estimating the distribution of NMR relaxation times from two dimensional data are firstly a data compression stage followed by application of the Butler-Reeds-Dawson (BRD) algorithm, and secondly a primal dual interior point method using a preconditioned conjugate gradient (PCG). Both of these methods have been presented in the literature as requiring a truncated singular value decomposition of matrices representing the exponential kernels. Other matrix factorisations are applicable to each of these algorithms, and which demonstrate the different fundamental principles behind the operation of the algorithms. In the case of the data compression approach the most appropriate matrix decomposition specifically designed for this task is the rank-revealing QR (RRQR) factorisation. In the case of the interior point method, the most appropriate method is the LDL factorisation with diagonal pivoting, also known as the Bunch-Kaufman-Parlett factorisation. The details of these differences are discussed, and the performances of the algorithms are compared numerically

    Disciplining customers at the Grand Seaside Hotel

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    The Grand Seaside Hotel is a large five-star hotel in an Australian Coastal town. It is a place that not only aspires to provide excellent service but that also seeks to reconcile two apparently divergent demands: the need for customized service and the efficient management of business operations. To commit staff to the provision of service excellence, management has introduced a customer service programme that relies on various forms of training and rewards, as well as a guest response system. The customer service programme, particularly the use of guest questionnaires, appear as disciplinary strategies that aim to produce service encounters in which both staff and guests are 'normalized'. The main loci of ethnographic data collection for this paper are regular Management Briefings. Through data collected from these, the paper investigates the use of the 'imaginary' in constituting service encounters and guest expectations. It interprets these in terms of Foucault's Panoptic analysis to identify the immanent mechanisms of discipline in these customer service programmes

    How Perceived Privacy Risk Determines People’s Willingness to Use Online Fashion Technologies

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    The subjective perception of Risk, Security, and Privacy in using online platforms and technologies determines to a large extent customers’ behaviours on these platforms. Accordingly, in this applied research project we have empirically explored how procedural anonymity and privacy influence customers’ willingness to use an online fitting application for fashion. Moreover, we have developed a psychometric tool that captures the psycholog ical variables (e.g., trust, perceived privacy risk, perceived privacy control, and online self-disclosure behaviour) of using online fashion technology. Furthermore, we will report the psychological factors that predict customers’ willingness to use online technology for fashion (e.g., online fitting application)

    E-cigarettes, Hookah Pens and Vapes: Adolescent and Young Adult Perceptions of Electronic Nicotine Delivery Systems: Table 1.

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    Most studies have assessed use of “e-cigarettes” or “electronic cigarettes,” potentially excluding new electronic nicotine delivery systems (ENDS), such as e-hookahs and vape pens. Little is known about how adolescents and young adults perceive ENDS and if their perceptions vary by sub-type. We explored ENDS perceptions among these populations

    Ceratoscopelus maderensis : pecular sound-scattering layer identified with this myctophid fish

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    Reprint. Science, vol. 160, no. 3831, 1968, pp. 991-993. Originally issued as Reference No. 68-58, series later renamed WHOI-.A sound- scattering layer, composed of discrete hyperbolic echo-sequences and apparently restricted to the Slope Water region of the western North Atlantic, has been identified from the Deep Submergence Research Vehicle ALVIN with schools of the myctophid fish Ceratoscopelus maderensis. By diving into the layer and using ALVIN's echo-ranging sonar, we approached and visually identified the sound scatterers. The number of echo sequences observed with the surface echo-sounder (1 /23. 76 x 105 cubic meters of water) checked roughly with the number of sonar targets observed from the submarine (1/7. 45 x 105 cubic meters) . The fish schools appeared to be 5 to 10 meters thick, 10 to 100 meters in diameter, and on centers 100 to 200 meters apart. Density within schools was estimated at 10 to 15 fish per cubic meter.Supported in part by contracts Nonr-3484(00) and Nonr-4029(00) and by NSF grant GB-4431

    pp-sdsd shell gap reduction in neutron-rich systems and cross-shell excitations in 20^{20}O

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    Excited states in 20^{20}O were populated in the reaction 10^{10}Be(14^{14}C,α\alpha) at Florida State University. Charged particles were detected with a particle telescope consisting of 4 annularly segmented Si surface barrier detectors and γ\gamma radiation was detected with the FSU γ\gamma detector array. Five new states were observed below 6 MeV from the α\alpha-γ\gamma and α\alpha-γ\gamma-γ\gamma coincidence data. Shell model calculations suggest that most of the newly observed states are core-excited 1p-1h excitations across the N=Z=8N = Z = 8 shell gap. Comparisons between experimental data and calculations for the neutron-rich O and F isotopes imply a steady reduction of the pp-sdsd shell gap as neutrons are added

    Finite element modelling of cochlear electrical coupling

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    The operation of each hair cell within the cochlea generates a change in electrical potential at the frequency of the vibrating basilar membrane beneath the hair cell. This electrical potential influences the operation of the cochlea at nearby locations and can also be detected as the cochlear microphonic signal. The effect of such potentials has been proposed as a mechanism for the non-local operation of the cochlear amplifier, and the interaction of such potentials has been thought to be the cause of the broadness of cochlea microphonic tuning curves. The spatial extent of influence of these potentials is an important parameter for determining the significance of their effects. Calculations of this extent have typically been based on calculating the longitudinal resistance of each of the scalae from the scala cross sectional area, and the conductivity of the lymph. In this paper, the range of influence of the electrical potential is examined using an electrical finite element model. It is found that the range of influence of the hair cell potential is much shorter than the conventional calculation, but is consistent with recent measurements
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