118 research outputs found

    A wireless multi-sensor subglacial probe: design and preliminary results

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    This paper introduces a new way to investigate in situ processes, the wireless multi-sensor probe, as part of an environmental sensor network. Instruments are housed within a 'probe' which can move freely and so behave like a clast. These were deployed in the ice and till at Briksdalsbreen, Norway. The sensors measure temperature, resistivity, case stress, tilt angle and water pressure and send their data to a base station on the glacier surface via radio links. These data are then forwarded by radio to a reference station with mains power 2.5 km away, from where they are sent to a web server in the UK. The system deployed during 2004/05 was very successful and a total of 859 probe days worth of data from the ice and till were collected, along with GPS, weather and diagnostic data about the system

    Fuzzy logic control for use in in-pipe mobile robotic system navigation

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    This paper presents a fuzzy logic control for the navigation of a mobile robotic system in gas pipelines. The robotic system is designed for a local gas distribution pipeline network with 150-300mm diameter pipes; common pipe fittings in use are straight and bend sections, reducers and slope pipe sections. The navigation problem forms a part of the current development of a new modular and semi-autonomous vehicle system. The vehicle control and navigation technique is implemented using a two-mode controller consisting of a proportional-integral-derivative (PID) and fuzzy logic control. The PID controller is responsible for direct control of the actuators, while the fuzzy logic controller is used to evaluate as well as to define the sensor outputs such as speed, climbing angle and rate of climbing angle in order to perceive the different types of pipe environment and vehicle actions. Since the navigation problem involves a multivariable input-output (MIMO) system, a cascaded hierarchical fuzzy model configuration is used to reduce the dimensionality of the fuzzy model. The fuzzy navigation controller is thus an interlink fuzzy subsystem of the pipe environment recognition and action adjustment subsystems. Results of simulations and laboratory experiments are presented to demonstrate the ability of the control strategy. A brief description of the mobile robotic system used is presented as background

    Design of a semi-autonomous modular robotic vehicle for gas pipeline inspection

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    This paper presents a new solution for inspecting and repairing defects in live gas pipelines. The proposed approach is the development of a modular and semi-autonomous vehicle system. The robotic system has a drive mechanism, capable of navigating and adjusting its orientation in various configurations of pipelines. Other features of the system are cable-free communications, semi-autonomous motion control as well as integration of sensory devices. The robotic system is designed to traverse in 150-300 mm diameter pipes through straight and curved sections, junctions and reducers. The vehicle control and navigation technique is implemented using a two-mode controller consisting of a proportional-integral-derivative (PID) and fuzzy logic control. Unlike other available systems, the vehicle employs proprioceptive sensors to monitor its own states. The fuzzy logic controller is used to evaluate the sensor outputs such as speed, climbing angle and rate of change of climbing angle. This control technique allows the vehicle to drive and adapt in a partially observable gas pipe system. Laboratory experiment results are presented. The paper also describes a cable-free communication method for the system. A brief account of typical pipe environments and currently available inspection tools is presented as background information

    Deploying a Sensor Network in an Extreme Environment

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    A wireless sensor network has been designed and deployed to gather data from nodes on and inside glaciers. This paper describes the solutions to power management, radio communications, management and discusses the performance of the final system. 18 months of data have now been received, which provide an insight not only into the glacier’s behaviour but on the design decisions. The system uses custom PIC-based sensor nodes and an ARM-based base station which controls weather and differential GPS. Different versions have been installed in Norway from 2003-5 and this paper describes the lessons learnt from coping with the extreme conditions found in glaciers

    Family Unification from Universality

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    A direct consequence of the occurrence of fermion families is the invariance of currents under certain groups of (universality) transformations. We show how these universality groups can themselves be used to find and study grand family unification models. Identifying two independent - weak and strong - universality groups and assuming that the grand unification group is SU(8N), its subgroup respecting either weak or strong universality is shown to be G = SU(2)xU(1)xSU(3). The fundamental representation of SU(8N) decomposes as N families of leptons and quarks. In the G-invariant limit, all fermions are left-handed. A mechanism for generating the correct number of right-handed fermions with the correct couplings so as to give pure vector colour and electromagnetic currents is exhibited. Universality is shown to result most naturally from a preonic structure of fermions. In such a preonic picture there are no ultraheavy gauge bosons and no anomaly or hierarchy problem.Comment: 30 page

    Production and Decay of D_1(2420)^0 and D_2^*(2460)^0

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    We have investigated D+πD^{+}\pi^{-} and D+πD^{*+}\pi^{-} final states and observed the two established L=1L=1 charmed mesons, the D1(2420)0D_1(2420)^0 with mass 242122+1+22421^{+1+2}_{-2-2} MeV/c2^{2} and width 2053+6+320^{+6+3}_{-5-3} MeV/c2^{2} and the D2(2460)0D_2^*(2460)^0 with mass 2465±3±32465 \pm 3 \pm 3 MeV/c2^{2} and width 2876+8+628^{+8+6}_{-7-6} MeV/c2^{2}. Properties of these final states, including their decay angular distributions and spin-parity assignments, have been studied. We identify these two mesons as the jlight=3/2j_{light}=3/2 doublet predicted by HQET. We also obtain constraints on {\footnotesize ΓS/(ΓS+ΓD)\Gamma_S/(\Gamma_S + \Gamma_D)} as a function of the cosine of the relative phase of the two amplitudes in the D1(2420)0D_1(2420)^0 decay.Comment: 15 pages in REVTEX format. hardcopies with figures can be obtained by sending mail to: [email protected]

    Measurement of the branching fraction for Υ(1S)τ+τ\Upsilon (1S) \to \tau^+ \tau^-

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    We have studied the leptonic decay of the Υ(1S)\Upsilon (1S) resonance into tau pairs using the CLEO II detector. A clean sample of tau pair events is identified via events containing two charged particles where exactly one of the particles is an identified electron. We find B(Υ(1S)τ+τ)=(2.61 ± 0.12 +0.090.13)B(\Upsilon(1S) \to \tau^+ \tau^-) = (2.61~\pm~0.12~{+0.09\atop{-0.13}})%. The result is consistent with expectations from lepton universality.Comment: 9 pages, RevTeX, two Postscript figures available upon request, CLNS 94/1297, CLEO 94-20 (submitted to Physics Letters B

    Measurement of the Decay Asymmetry Parameters in Λc+Λπ+\Lambda_c^+ \to \Lambda\pi^+ and Λc+Σ+π0\Lambda_c^+ \to \Sigma^+\pi^0

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    We have measured the weak decay asymmetry parameters (\aLC ) for two \LC\ decay modes. Our measurements are \aLC = -0.94^{+0.21+0.12}_{-0.06-0.06} for the decay mode Λc+Λπ+\Lambda_c^+ \to \Lambda\pi^+ and \aLC = -0.45\pm 0.31 \pm 0.06 for the decay mode ΛcΣ+π0\Lambda_c \to \Sigma^+\pi^0 . By combining these measurements with the previously measured decay rates, we have extracted the parity-violating and parity-conserving amplitudes. These amplitudes are used to test models of nonleptonic charmed baryon decay.Comment: 11 pages including the figures. Uses REVTEX and psfig macros. Figures as uuencoded postscript. Also available as http://w4.lns.cornell.edu/public/CLNS/1995/CLNS95-1319.p

    Associations of autozygosity with a broad range of human phenotypes

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    In many species, the offspring of related parents suffer reduced reproductive success, a phenomenon known as inbreeding depression. In humans, the importance of this effect has remained unclear, partly because reproduction between close relatives is both rare and frequently associated with confounding social factors. Here, using genomic inbreeding coefficients (F-ROH) for >1.4 million individuals, we show that F-ROH is significantly associated (p <0.0005) with apparently deleterious changes in 32 out of 100 traits analysed. These changes are associated with runs of homozygosity (ROH), but not with common variant homozygosity, suggesting that genetic variants associated with inbreeding depression are predominantly rare. The effect on fertility is striking: F-ROH equivalent to the offspring of first cousins is associated with a 55% decrease [95% CI 44-66%] in the odds of having children. Finally, the effects of F-ROH are confirmed within full-sibling pairs, where the variation in F-ROH is independent of all environmental confounding.Peer reviewe
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