530 research outputs found
Quality assurance and testing before, during, and after construction of semiconductor tracking detectors
No full textМикростриповые детекторы на основе N-кремния ЗТМК
No full textНастоящая работа посвящена изучению характеристик микростриповых детекторов (МСД), изготовленных на основе Запорожского титано-магниевого комбината (ЗТМК, Украина).Эта работа финансировалась Министерством науки Украины. Авторы выражают благодарность за поддержку работы.
Авторы также выражают благодарность за поддержку и помощь в этой работе коллаборации эксперимента ALICE CERN. Особую благодарность авторы выражают за полезные обсуждения и помощь O. Runolfsson, P. Giubellino и сотрудникам, принимавшим участие в этой работе
IOT system for Bluetooth based Origin-Destination studies
No full textDesigning and modelling a transportation system is a complicated, yet crucial task that demands comprehensive study of public needs. An important aspect of the process is specifying the characteristics of traffic schemes, which include vehicle classification, origin/destination (O/D), travel time (TT), and vehicle occupancy, in addition to other factors. A more thorough understanding of these factors will lead to improved transportation planning.
This thesis proposes the development of an Internet of Things (IoT) system that integrates two systems, namely Bluetooth (BT) identification and vehicle classification, for monitoring route choices per vehicle class. The extant system consists of one BT identification/vehicle classification unit deployed at an Oklahoma port of entry, along with a number of BT identification stations deployed at various locations across Oklahoma’s roadways. As vehicles travel over magnetometer nodes, sensors measure changes in magnetic field (i.e., vehicle magnetic signature) for defining each vehicle’s time of arrival and time of departure. Stated times will be used to estimate magnetic length of a passing vehicle for the purpose of classifying the vehicle. During this process, the BT ID of detected BT mobile devices in the vehicle is captured using BT identification stations.
Algorithms were developed to associate detected BT addresses to the corresponding vehicles with exceptional accuracy. BT addresses are planned to be sent alongside the vehicle group to a server where they will be matched by multiple stations as the vehicle travels on observed roadways. Hence, active monitoring of route choice and TT per vehicle class is achieved using only inexpensive BT stations
Sizeable proton polarizations in frozen alcohol mixtures
No full textWe present here preliminary results of a work which is part of a research
programme for high proton polarizations in highly hydro-genated substances. The
method of polarization was the "solid ef-fect". The samples were ethanol-water,
ethanol-methanol, and et~a nol-propanol mixtures doped with porphyrexide, a
free radical with a formula (CH3) 2 CN(:O)C(:NH)NHC:NH lJ. The mixtures were
saturated at room temperature with about 3 % by weight of porphyrexide. The
experiments were carried out in a field of 25 kG, at temperatures around 1.05°
K, obtained in a continuous flow cryostat 2J ; the cooling time from ro0~
temperature to liquid helium temperature was 55 minutes. The samples were
contained in a rectangular holder made of copper, 3.5 x 7 x 14 mm, closed on one
side by a te-flon window 3 x 6 mm. This holder was located inside a 18 cm3
copper cavity filled with helium, and connected to a 20 W carcinotron
oscillating at 70 Gc/s. The polariz~tion was measured by NMR as in the Saclay-
CERN polarized targets 3J, the coil being immersed in the samples and care being
taken not to saturate the NMR signals. Maximum polarizations of 35 ± 2 % were
obtained for the lowest attainable temperature, with a reduced microwave power
of about 500 mW. The polarization depends markedly on the concentration of the
various mixtures, as shown is figures 1, 2 and 3. Figure 4 shows the melting
point of ethanol-water mixtures : a correlation seems to exist between the
melting point and the obtained polari-zations, although we are not able now to
understand why. No attempt has yet been made to observe the electronic resonance
line of the frozen free radical : from the known overall hyperfine splitting (30
gauss) and the anisotropy of the g-factor, we estimate its width to be between
60 and 90 gauss. No attempt has bee
Distributed Computation of Graph Spectrum, Eigenvector Centrality, and Solution to Linear Equations
No full textThis dissertation is devoted to the development of distributed algorithms, with which nodes in a large decentralized network can accomplish tasks that are seemingly difficult without an omniscient central node. The tasks include estimating the graph spectrum, from which each node can draw its own conclusion about the network structure, computing the eigenvector centrality, from which every node can judge its own importance in the network, and solving a system of linear equations whose data are scattered across the network or discovering that no solution exists. The ability to perform these tasks enhances the capability of existing and emerging networks such as smart power grids, social networks, and ad hoc sensor networks, potentially allowing them to function in ways that are not previously thought to be possible.
We begin with the design of a novel, two-stage distributed algorithm that enables nodes in an undirected and connected graph to jointly estimate the spectrum of a matrix associated with the graph, which includes the adjacency and Laplacian matrices as special cases. In the first stage, the algorithm uses a discrete-time linear iteration and the Cayley-Hamilton theorem to convert the problem into one of solving linear equations, where each equation is known to a node. In the second stage, if the nodes happen to know that said matrix is cyclic, the algorithm uses a Lyapunov approach to asymptotically solve the equations with an exponential rate of convergence. Otherwise, it uses a random perturbation approach and a structural controllability result to approximately solve the equations with an error that can be made small.
We then consider the fundamental problem of cooperatively solving a general system of linear equations over a network, for which a continuous-time distributed algorithm is devised. We show that the algorithm enables the nodes to asymptotically agree on a solution when there are infinitely many solutions, determine the solution when there is exactly one, and detect that no solution exists when there are none. We also establish that the algorithm is globally exponentially convergent, derive an explicit lower bound on its convergence rate that it can do no worse than, and prove that the larger the network's algebraic connectivity, or the further away from being singular the system of equations, the larger this lower bound.
Finally, we address the open question of whether it is possible to calculate eigenvector centrality over a network. We provide an affirmative answer by presenting a class of continuous-time distributed algorithms and an asynchronous gossip algorithm, which allow every node in a graph to compute the th entry of the Perron-Frobenius eigenvector of a symmetric, Metzler, and irreducible matrix induced by the graph, as well as the corresponding eigenvalue, when node knows only row of the matrix. We show that each continuous-time distributed algorithm is a nonlinear networked dynamical system with a skew-symmetric structure, whose state is guaranteed to stay on a sphere, remain nonnegative, and converge asymptotically to said eigenvector at an rate. We also show that under a mild assumption on the gossiping pattern, the gossip algorithm is able to do the same
A silicon tracker for track extrapolation into nuclear emulsions
No full textThis paper describes the construction of a silicon tracker built to investigate how well silicon detectors can predict the position of particles in nuclear emulsions over a large area. The tracker consists of 72 single-sided silicon microstrip detectors with a total surface of 0.13 m/sup 2/ distributed over four layers, providing two x and two y coordinate measurements. The set-up was installed in a CERN PS pion beam in September 1997. (12 refs)
Характеристики и радиационная стойкость двустороннего микрострипового детектора с поликремниевыми резисторами смещения
No full textThe characteristics and radiation tolerance of a double-sided microstrip detector (DSMD) were studied, and the suitability of the detector to the ALICE experiment requirements was analyzed. The sensitive area of the silicon microstrip detector measures 40x75 mm. The DSMD consists of 750 registering strips on each side. The strip pitch is 100 mm and the strip length is 40 mm. Strips of the p+-side were oriented parallel to the side edge, the n+-strips were placed at 30 mrad stereo angle with respect to p+-strips and were separated by a common p+-stop structure. Both p+- and n+-strips are biased by integrated polysilicon resistors with a resistance no less than 10 MOhm. The data readout is realized with use of 120 pF coupling capacitors. The radiation tolerance of the microstrip detector was studied using 20 MeV electrons. The leakage current increases from 2 up to 5 nA per one strip and the interstrip resistance decreases from 43 down to 30 GOhm after 10 krad irradiation dose. The other DSMD features remain unchanged under irradiation. To evaluate the detector efficiency, the yield of good coupling capacitors and biasing resistors, as well as strip leakage currents, interstrip resistance and interstrip capacitance were studied. Based on the data obtained, the number of defective strips is found not to exceed 3%; this provides the required detector efficiency of about 97%.The authors are very thankful to many colleagues for
the valuable discussions and constructive remarks,
especially P. Giubellino and O. Runolfsson. This work
was supported by INTAS under the Grant 96-0678
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