3,884 research outputs found
The MRPC-based ALICE Time-Of-Flight detector: status and performance
The large Time-Of-Flight (TOF) array is one of the main detectors devoted to
charged hadron identification in the mid-rapidity region of the ALICE
experiment at the LHC. It allows separation among pions, kaons and protons up
to a few GeV/c, covering the full azimuthal angle and -0.9 < eta < 0.9. The TOF
exploits the innovative MRPC technology capable of an intrinsic time resolution
better than 50 ps with an efficiency close to 100% and a large operational
plateau; the full array consists of 1593 MRPCs covering a cylindrical surface
of 141 m2. The TOF detector has been efficiently taking data since the first pp
collisions recorded in ALICE in December 2009. In this report, the status of
the TOF detector and the performance achieved for both pp and Pb--Pb collisions
are described.Comment: 4 pages, 6 figure
Photonic magnetic metamaterial basics
Cataloged from PDF version of article.In the present study, we provide a detailed analysis for the study of photonic metamaterials. We demonstrate the polarization and orientation dependent transmission response of split ring resonators at the infrared and visible band. We provided optical measurements only for one case, in which electric component of the incident field was coupled to planar split ring resonator array. We consecutively studied (i) frequency tuning, (ii) effect of resonator density, (iii) shifting magnetic resonance frequency by changing the resonator shape, and (iv) effect of metal loss and plasma frequency. The study provides an overlook for the candidate applications such as the enhancement of power passing through an electrically small hole, negative index metamaterials and optical metamaterial absorbers. (C) 2010 Elsevier B.V. All rights reserved
A panel analysis of UK industrial company failure
We examine the failure determinants for large quoted UK industrials using a panel data set
comprising 539 firms observed over the period 1988-93. The empirical design employs data
from company accounts and is based on Chamberlain’s conditional binomial logit model,
which allows for unobservable, firm-specific, time-invariant factors associated with failure
risk. We find a noticeable degree of heterogeneity across the sample companies. Our panel
results show that, after controlling for unobservables, lower liquidity measured by the quick
assets ratio, slower turnover proxied by the ratio of debtors turnover, and profitability were
linked to the higher risk of insolvency in the analysis period. The findings appear to support
the proposition that the current cash-flow considerations, rather than the future prospects of
the firm, determined company failures over the 1990s recession
Asymmetric Fabry-Perot-type transmission in photonic-crystal gratings with one-sided corrugations at a two-way coupling
Cataloged from PDF version of article.Strongly asymmetric Fabry-Perot-type transmission arising at the two-way coupling has been studied in the case of normal incidence for slabs of two-dimensional photonic crystals (PCs) with one-sided corrugations that are made of linear isotropic materials. Comparing to the scenario of unidirectional transmission known for the structures with broken spatial inversion symmetry that requires zero order being uncoupled, in the studied mechanism zero order is either the sole order or one of the orders that may be coupled to a Floquet-Bloch mode. Contrary to the earlier studies of asymmetric transmission at the coupled zero order, structures with nondeep corrugations are considered, which allow one to combine Fabry-Perot-type total-transmission maxima with diffractions in a desired way. At a proper choice of PC lattice and corrugation parameters, higher orders can dominate in Fabry-Perot-type transmission at the noncorrugated-side illumination and also at the total-transmission maxima, whereas only zero order contributes to the transmission at the corrugated-side illumination. As a result, strong asymmetry can be obtained without uncoupling of zero order but it invokes the unidirectional contribution of higher orders. The presented results show that the entire structure can be approximately decomposed into the two independent, regular and grating (nonregular), parts whose contributions to the transmission are additive. Multiple asymmetric transmission maxima can coexist with a rather high equivalent group index of refraction. Possible applications of the studied transmission mechanism are discussed
Stability of a “Manipulator–Drill” System with Force Control and Time Delay
A mathematical model of a manipulator-tool system with time delay present in the feedback loop is analyzed. The drilling process with constant feed force and control of force is the subject of this research. It is shown that the time delay in the control loop is a factor that influences the system’s stability. The minimum possible gain factor necessary for a stable system is obtained. This factor depends on the time delay and the stiffness of the sensor. The theoretically obtained results are compared to experiments
Design of Miniaturized Narrowband Absorbers Based on Resonant-Magnetic Inclusions
Cataloged from PDF version of article.In this paper, we present the design of miniaturized narrowband-microwave absorbers based on different kinds of magnetic inclusions. The operation of the proposed components originates from the resonance of a planar array of inclusions excited by an incoming wave with a given polarization. As in common absorber layouts, a 377 Omega resistive sheet is also used to absorb the electromagnetic energy of the impinging field. Since the planar array of magnetic inclusions behaves at its resonance as a perfect magnetic conductor, the resistive sheet is placed in close proximity of the resonating inclusions, without perturbing their resonance condition. In contrast to other typical absorber configurations presented in the literature, the absorber proposed in this paper is not backed by a metallic plate. This feature may be useful for stealth applications, as discussed thoroughly in the paper. The other interesting characteristic of the proposed absorbers is the subwavelength thickness, which has shown to depend only on the geometry of the basic resonant inclusions employed. At first, regular split-ring resonators (SSRs) disposed in an array configuration are considered and some application examples are presented. Absorbers based on SRRs are shown to reach thickness of the order of lambda(0)/20. In order to further squeeze the electrical thickness of the absorbers, multiple SRRs and spiral resonators are also used. The employment of such inclusions leads to the design of extremely thin microwave absorbers, whose thickness may even be close to lambda(0)/100. Finally, some examples of miniaturized absorbers suitable for a practical realization are proposed
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