1,721,721 research outputs found
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Improvement and calibration of a thermal conductivity measurement setup
No full textThe outer tracker of the Compact Muon Solenoid (CMS) Detector will be upgraded as part of the upgrade of the Large Hadron Collider (LHC) to the High-Luminosity LHC.The Tracker Endcap Double-Discs (TEDD), that are part of the outer tracker are built and integrated with modules at DESY. The CMS detector and with it the TEDD will be cooled to evacuate the generated heat of the modules, to minimize their leakage current due to the heavy irradiation from the passing through particles and avoid thermal runaway. Therefore, a good thermal coupling of the modules to the cooling structure of the TEDD is necessary. This creates the necessity for new materials, that have a high thermal conductivity, while having a large radiation length and a small density. A custom setup for thermal conductivity measurements was developed, with which the thermal conductivity of suitable materials can be precisely measured. This bachelor thesis provides an overview about the operation of the custom thermal conductivity measurement setup and the measurement process.Additionally, the setup is improved as a part of the thesis by installing a Peltier element based temperature control, to enable faster and more frequent measurements. The used thermistors and the full setup are calibrated as preparation for a calibration campaign in the context of the Detector Research and Development Collaboration for Mechanics & Cooling of Future Vertex and Tracking Systems (DRD8), that has the objective to make results comparable to those of other institutes.The thermistors, that are used in the setup, are calibrated for a temperature range from 2 ◦C to 30 ◦C. For one thermistor, the decision to exclude it from the data analysis was confirmed. For the other thermistors, the standard deviation of the temperature difference between the corrected temperature measurements and the reference temperature measurement is below 0.016 ◦C. The proportional-integral-derivative (PID) control for the Peltier element is calibrated to ensure a more stable temperature control, that prevents large fluctuations. The values Kp = 80, TN = 20 and TV = 5 were determined for the PID parameters proportional gain Kp, integral time TN and derivative time TV to enable a control with these characteristics. The standarddeviation of the temperature control was achieved to be below 0.01 ◦C. The prevention of larger fluctuations significantly shortens the time one measurement takes to achieve morefrequent measurements.To calibrate the modified setup, brass alloy CW614N and sapphire glass samples were measured. The results were compared to the respective nominal value and the mean calibration factor ccal = 0.984 was extracted. That calibration factor will be multiplied with the measured thermal conductivity of future measurements to obtain the resulting thermalconductivity
Elektrische Vermessung und Finite-Elemente-Simulation von Si-Dioden für BCM1F am CMS-Detektor
No full textThe BCM1F detector at the CMS experiment is responsible for the measurement of theluminosity, as well as the beam-induced background. It is assumed that the sensors will haveto be replaced during Run 3 of the LHC, which is why work is already underway to build areplacement system. For this purpose, a set of 24 new silicon diodes is needed, which first haveto be tested for their functionality. In the scope of this bachelor thesis the electrical qualificationof the Si-diodes takes place. For this purpose, IV- and CV-measurements were performed andthe depletion voltage VFD was calculated. Furthermore, the coupling capacitance CP andthe resistance RP between DC- and AC-pad were measured. It was observed that the IVcurve deviates strongly from the theoretically expected curve. For a better understanding ofthis phenomenon, a TCAD simulation was carried out, with the help of which a possibleexplanation for the shape of the IV curve could be identified.
Commissioning of a cold test system for Outer Tracker Endcap half disks for the Phase-2 upgrade of the CMS experiment
No full textThe Large Hadron Collider will be upgraded to extend its lifetime and improve various components. With the upgrade to the High-Luminosity-LHC the instantaneous luminosity will increaseto 5 · 1034 cm−2s−1 and the total integrated luminosity to at least 3000 fb−1. To deal with the increased luminosity, the detectors must be upgraded. At the CMS experiment almost the whole detector will be upgraded. This includes the Tracker, which tracks the trajectory of a particle and measures its momentum. To cope with the increased number of events per bunch crossing, the Outer Tracker will be included in the level-1 trigger system. The Outer Tracker consists of a Barrel part and two Endcaps. At the DESY in Hamburg in the CMS Tracker Upgrade group one of the new Outer Tracker Endcaps will be produced. All parts produced for the High-Luminosity-upgrade must be tested before they are installed at the LHC and taken into operation. These tests themselves must also be tested and commissioned.This Bachelor thesis describes how the temperature sensors of a Pixel-Strip-Silicon-sensor-module (PS-module) were calibrated and how a cold test system for Outer Tracker Endcap halfdisks, the so-called Sectortest, is taken into operation. The PS-module, whose sensors were calibrated, is a kick-off module and equipped with additional temperature sensors. This special PS-module is used to gain knowledge about the behaviour of PS-modules and the test setups and is named Galileo.The additional temperature NTC sensors were calibrated first in a temperature chamber. The internal temperature sensors of the PS-module were calibrated by fitting a linear function tothe temperatures of the additional glued sensors. As the linear function has a slope of 0.9, the temperature calibration would be off by approximately 5.5◦C if a constant offset were assumedand this offset was determined at room temperature. In the process of calibrating the PS-module it was observed that the PS-module needs 8 minutes to warm up when the power is turned on, while the Chiller used for cooling it down has an overshoot much smaller than the temperature difference due to the module warming up. The Galileo module cools down simultaneously with its carrier plate when the Burn-In gets cooled down. The Burn-In is a thermal test setup, where individual modules are tested. In the Burn-In tests for the production modules it will not be necessary to wait for the silicon sensor modules to thermalise.The drying and cooling of the Sectortest work well. During the commissioning test it was demonstrated that the Sectortest dries down to the required dew point within a few hours. Theexact time it takes to dry the Sectortest depends on the amount of dry air used. It was also shown that the required dew point was reached with comparatively low dry air flow indicating a good sealing of the box.Inside the Sectortest cooling box a temperature around −20◦C was achieved, which was the target temperature for this setup as this is also the target temperature for the conditions inside the detector. The process of the Sectortest cooling down was studied as well. 6 : 15 h after starting to cool down the Sectortest all sensors in the Sectortest show temperatures that are less than 0.5◦C away from their final temperature. After 13 : 30 h the temperatures are completely stable. When the temperature inside the Sectortest is stabilized, the temperature difference inside remains 7.4◦C. Therefore a fan system should be considered to ensure a more equal temperature distribution
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Precision metrology measurements for the CMS phase-2 Tracker upgrade
No full textThe LHC, along with all of its experiments, is going through an upgrade. The currentLHC, designed for an integrated luminosity of 300 fb , will be upgraded to the HighLuminosity LHC (HL-LHC), providing an increased collision rate and will deliver morethan 3000 fb luminosity. All LHC experiments will undergo an upgrade to cope withthe increased luminosity. For the upgrade of the CMS new endcaps have to be designedand built. The main mechanical element of the endcaps will be the half disks with embeddedcooling pipes and detector module positioning inserts. A prototype of a part ofthe endcap half disk has been built and is being studied. During the course of this thesis,measurements were carried out on the prototype to check the precision of various mechanicalelements such a reference inserts or the module inserts, which will be used toposition the detector modules. The measurements were carried out with the metrologyarm made specifically for precision measurements. In order to check the accuracy of thearm different studies were carried out such as the calibration of the probes and the influenceof the movement of the metrology arm with respect to the object. The result ofthe measurement of the prototype demonstrated the cause of a misalignment of inserts,however almost all positions were within specification
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