1,917 research outputs found

    A Fast Digital Integrator for magnetic measurements

    Get PDF
    In this work, the Fast Digital Integrator (FDI), conceived for characterizing dynamic features of superconducting magnets and measuring fast transients of magnetic fields at the European Organization for Nuclear Research (CERN) and other high-energy physics research centres, is presented. FDI development was carried out inside a framework of cooperation between the group of Magnet Tests and Measurements of CERN and the Department of Engineering of the University of Sannio. Drawbacks related to measurement time decrease of main high-performance analog-to-digital architectures, such as Sigma-Delta and integrators, are overcome by founding the design on (i) a new generation of successive-approximation converters, for high resolution (18-bit) at high rate (500 kS/s), (ii) a digital signal processor, for on-line down-sampling by integrating the input signal, (iii) a custom time base, based on a Universal Time Counter, for reducing time-domain uncertainty, and (iv) a PXI board, for high bus transfer rate, as well as noise and heat immunity. A metrological analysis, aimed at verifying the effect of main uncertainty sources, systematic errors, and design parameters on the instrument performance is presented. In particular, results of an analytical study, a preliminary numerical analysis, and a comprehensive multi-factor analysis carried out to confirm the instrument design, are reported. Then, the selection of physical components and the FDI implementation on a PXI board according to the above described conceptual architecture are highlighted. The on-line integration algorithm, developed on the DSP in order to achieve a real-time Nyquist bandwidth of 125 kHz on the flux, is described. C++ classes for remote control of FDI, developed as a part of a new software framework, the Flexible Framework for Magnetic Measurements, conceived for managing a wide spectrum of magnetic measurements techniques, are described. Experimental results of metrological and throughput characterization of FDI are reported. In particular, in metrological characterization, FDI working as a digitizer and as an integrator, was assessed by means of static, dynamic, and time base tests. Typical values of static integral nonlinearity of ±7 ppm, ±3 ppm of 24-h stability, and 108 dB of signal-to-noise-anddistortion ratio at 10 Hz on Nyquist bandwidth of 125 kHz, were surveyed during the integrator working. The actual throughput rate was measured by a specific procedure of PXI bus analysis, by highlighting typical values of 1 MB/s. Finally, the experimental campaign, carried out at CERN facilities of superconducting magnet testing for on-field qualification of FDI, is illustrated. In particular, the FDI was included in a measurement station using also the new generation of fast transducers. The performance of such a station was compared with the one of the previous standard station used in series tests for qualifying LHC magnets. All the results highlight the FDI full capability of acting as the new de-facto standard for high-performance magnetic measurements at CERN and in other high-energy physics research centres

    Metrological Characterization of an Improved DSP-Based On-line Integrator for Magnetic Measurements at CERN

    Get PDF
    An improved on-line version of the self-calibrating digital instrument for flux measurements on superconductive magnets for particle accelerators, prototyped at the European Organization for Nuclear Research (CERN) in cooperation with the University of Sannio, is proposed. The instrument acquires voltage arising from rotating coils transducers. Then, the samples are online integrated and suitably processed in order to achieve flux analysis time down to 2.0 ìs, with resolution of 50 ns. Details about hardware and firmware conception, on-line measurement principle, and preliminary results of metrological characterization of the prototype are provided

    Surface Response-based Behavioral Modeling of Accurate Digitizers: a Case Study on a Fast Digital Integrator at CERN

    Get PDF
    A statistical approach to behavioral modeling for assessing dynamic metrological performance during the concept design of accurate digitizers is proposed. A surface-response approach based on statistical experiment design is exploited for avoiding unrealistic hypothesis of linearity, optimizing simulation, exploring operating conditions systematically, as well as verifying identification and validation uncertainty. An actual case study on the dynamic metrological characterization of a Fast Digital Integrator for high-performance magnetic measurements at the European Organization for Nuclear Research (CERN) is presented

    Biological Strategies to Enhance Healing of the Avascular Area of the Meniscus

    Get PDF
    Meniscal injuries in the vascularized peripheral part of the meniscus have a better healing potential than tears in the central avascular zone because meniscal healing principally depends on its vascular supply. Several biological strategies have been proposed to enhance healing of the avascular area of the meniscus: abrasion therapy, fibrin clot, organ culture, cell therapy, and applications of growth factors. However, data are too heterogeneous to achieve definitive conclusions on the use of these techniques for routine management of meniscal lesions. Although most preclinical and clinical studies are very promising, they are still at an experimental stage. More prospective randomised controlled trials are needed to compare the different techniques for clinical results, applicability, and cost-effectiveness

    A RESEARCH ON EMISSION ALLOWANCE TRADING SYSTEM IN CHINA

    Get PDF
    随着环境问题的日益严重,各国政府开始将价格、税收、财政、信贷、收费、保险等经济手段运用到环境管理之中,推行一系列环境经济政策,排污权交易就是其中之一。排污权交易有着深厚的经济学基础,即环境纳污能力的商品化、市场化和外部不经济的内在化。排污权交易制度的实施可以在社会总污染治理成本最小化的前提下促进企业的减排以及治污技术的革新,且通过这种手段政府对环境质量的调控更加灵活。污染企业在排污权交易制度安排的激励下,不仅将治污减排视为企业的技术和合规管理,还可以通过对排污权市场价格的预测,对企业排污治污成本的精确核算,对减排行为进行经济评估,将排污管理融入到财务管理中。本文在总结分析比较美国、欧洲、日本的...Along with the increasingly serious environmental problems, governments try to apply economics principles, like price, tax, finance, credit, charge, insurance, to environmental policy. The emission allowance trade system is one of them. This policy can promote the enterprise to reduce the emission and improve the emission-reducing technology with minimizing the social pollution control cost, and t...学位:管理学硕士院系专业:管理学院会计系_会计学学号:1752006115128

    Minimally-invasive treatments for benign thyroid nodules: a Delphi-based consensus statement from the Italian minimally-invasive treatments of the thyroid (MITT) group

    Get PDF
    Benign thyroid nodules are a common clinical occurrence and usually do not require treatment unless symptomatic. During the last years, ultrasound-guided minimally invasive treatments (MIT) gained an increasing role in the management of nodules causing local symptoms. In February 2018, the Italian MIT Thyroid Group was founded to create a permanent cooperation between Italian and international physicians dedicated to clinical research and assistance on MIT for thyroid nodules. The group drafted this list of statements based on literature review and consensus opinion of interdisciplinary experts to facilitate the diffusion and the appropriate use of MIT of thyroid nodules in clinical practice. (#1) Predominantly cystic/cystic symptomatic nodules should first undergo US-guided aspiration; ethanol injection should be performed if relapsing (level of evidence [LoE]: ethanol is superior to simple aspiration = 2); (#2) In symptomatic cystic nodules, thermal ablation is an option when symptoms persist after ethanol ablation (LoE = 4); (#3) Double cytological benignity confirmation is needed before thermal ablation (LoE = 2); (#4) Single cytological sample is adequate in ultrasound low risk (EU-TIRADS 643) and in autonomously functioning nodules (LoE = 2); (#5) Thermal ablation may be proposed as first-line treatment for solid, symptomatic, nonfunctioning, benign nodules (LoE = 2); (#6) Thermal ablation may be used for dominant lesions in nonfunctioning multinodular goiter in patients refusing/not eligible for surgery (LoE = 5); (#7) Clinical and ultrasound follow-up is appropriate after thermal ablation (LoE = 2); (#8) Nodule re-treatment can be considered when symptoms relapse or partially resolve (LoE = 2); (#9) In case of nodule regrowth, a new cytological assessment is suggested before second ablation (LoE = 5); (#10) Thermal ablation is an option for autonomously functioning nodules in patients refusing/not eligible for radioiodine or surgery (LoE = 2); (#11) Small autonomously functioning nodules can be treated with thermal ablation when thyroid tissue sparing is a priority and 6580% nodule volume ablation is expected (LoE = 3)

    Combined search for the quarks of a sequential fourth generation

    Get PDF
    Results are presented from a search for a fourth generation of quarks produced singly or in pairs in a data set corresponding to an integrated luminosity of 5 inverse femtobarns recorded by the CMS experiment at the LHC in 2011. A novel strategy has been developed for a combined search for quarks of the up and down type in decay channels with at least one isolated muon or electron. Limits on the mass of the fourth-generation quarks and the relevant Cabibbo-Kobayashi-Maskawa matrix elements are derived in the context of a simple extension of the standard model with a sequential fourth generation of fermions. The existence of mass-degenerate fourth-generation quarks with masses below 685 GeV is excluded at 95% confidence level for minimal off-diagonal mixing between the third- and the fourth-generation quarks. With a mass difference of 25 GeV between the quark masses, the obtained limit on the masses of the fourth-generation quarks shifts by about +/- 20 GeV. These results significantly reduce the allowed parameter space for a fourth generation of fermions.Comment: Replaced with published version. Added journal reference and DO

    Compressed representation of a partially defined integer function over multiple arguments

    Get PDF
    In OLAP (OnLine Analitical Processing) data are analysed in an n-dimensional cube. The cube may be represented as a partially defined function over n arguments. Considering that often the function is not defined everywhere, we ask: is there a known way of representing the function or the points in which it is defined, in a more compact manner than the trivial one

    Measurement of the t t-bar production cross section in the dilepton channel in pp collisions at sqrt(s) = 7 TeV

    Get PDF
    The t t-bar production cross section (sigma[t t-bar]) is measured in proton-proton collisions at sqrt(s) = 7 TeV in data collected by the CMS experiment, corresponding to an integrated luminosity of 2.3 inverse femtobarns. The measurement is performed in events with two leptons (electrons or muons) in the final state, at least two jets identified as jets originating from b quarks, and the presence of an imbalance in transverse momentum. The measured value of sigma[t t-bar] for a top-quark mass of 172.5 GeV is 161.9 +/- 2.5 (stat.) +5.1/-5.0 (syst.) +/- 3.6(lumi.) pb, consistent with the prediction of the standard model.Comment: Replaced with published version. Included journal reference and DO
    corecore