5,113 research outputs found
Robustness of roundabout metering systems (RMS)
No full textA simple explorative study shows that roundabouts are too small to be equipped with permanently operating traffic lights. The conclusion of a recent, more detailed study was not fundamentally different to this: at a small two-lane roundabout with four legs and with leg-by-leg control the shortest green time is 11 to 13 seconds, irrespective of the volume of traffic on the least busy leg. This results in a great deal of unnecessary waiting time. Leg-by-leg control at a four-lane roundabout is therefore not regarded as a robust solution. In view of this, at small roundabouts incidental metering signals are used. At single lane roundabouts, metering signals provide a more balanced distribution of the waiting time, whereas at two-lane roundabouts, the metering signals also have the potential to improve traffic flow. This was shown as early as 2003, in research conducted in collaboration with the author. This article explains the theoretical background to the research. In addition, general design principles for roundabout metering signals (RMS) are deduced. In 2011, research carried out as part of a Master's thesis supervised by the author studied the robustness of RMS for various traffic loads and roundabout types. Two types of roundabout were studied: \u95 a standard turbo roundabout and \u95 a spiral roundabout. A simulation model was used that underestimated rather than overestimated the effect of an RMS. The results show that, even under less than optimum conditions, traffic performance of the whole roundabout was improved by approximately 10 %. Traffic performance in the relevant (saturated) leg improved by more than this, namely by 15-45 %. The reduction of time loss at all legs taken together is even greater: -20 % to -50 % in total, and as much as -70 % for the saturated leg. Notably, altering a dominant load pattern can even reduce waiting time in the leg with the metering light.Transport and PlanningCivil Engineering and Geoscience
Reference materials (RMs) for analysis of the human factor II (prothrombin) gene G20210A mutation
No full textThe Scientific Committee of Molecular Biology Techniques (C-MbT) in Clinical Chemistry of the IFCC has initiated a joint project in co-operation with the European Commission, Joint Research Centre, Institute of Reference Materials and Measurements to develop and produce plasmid-type reference materials (RMs), for the analysis of the human prothrombin gene G20210A mutation. Although DNA tests have a high impact on clinical decision-making and the number of tests performed in diagnostic laboratories is high, issues of quality and quality assurance exist, and currently only a few RMs for clinical genetic testing are available. A gene fragment chosen was produced that spans all primer annealing sites published to date. Both the wild-type and mutant alleles of this gene fragment were cloned into a pUC18 plasmid and two plasmid RMs were produced. In addition, a mixture of both plasmids was produced to mimic the heterozygous genotype. The present study describes the performance of these reference materials in a commutability study, in which they were tested by nine different methods in 13 expert laboratories.. This series of plasmid RMs are, to the best of our knowledge, the first plasmid-type clinical genetic RMs introduced worldwide
WORKSHOP PENGGUNAAN REFERENCE MANAGEMENT SOFTWARE (RMS) BAGI DOSEN DAN MAHASISWA STEI AL-FURQON PRABUMULIH
No full textPenggunaan Reference Management Software (RMS) seperti Mendeley, Endnote, dan Zotero adalah salah satu persyaratan yang terkadang diabaikan dalam publikasi ilmiah. Tujuan workshop penggunaan Reference Management Software (RMS) bagi dosen dan mahasiswa STEI Al-Furqon Prabumulih adalah untuk meningkatkan kesadaran akan pentingnya penggunaan RMS dalam publikasi dan memberikan kesempatan kepada dosen dan mahasiswa untuk menerapkan beberapa RMS yang penting untuk memenuhi persyaratan publikasi di jurnal berkualitas. Kegiatan ini berlangsung selama dua hari melibatkan para dosen dan mahasiswa STEI Al-Furqon Prabumulih. Tim dibagi dalam tiga kelompok berdasarkan materi yang disampaikan yaitu mengenai RMS Mendeley, RMS Zotero dan RMS EndNote. Hasil PKM menunjukkan respon yang positif terhadap workshop yang diselenggarakan terbukti dengan tingginya antusias para dosen dan mahasiswa dalam mengikuti kegiatan workshop ini
On Bipartite Matching under the RMS Distance
No full textGiven two sets A and B of n points each in R 2, we study the problem of computing a matching between A and B that minimizes the root mean square (rms) distance of matched pairs. We can compute an optimal matching in O(n 2+δ) time, for any δ> 0, and an ε-approximation in time O((n/ε) 3/2 log 6 n). If the set B is allowed to move rigidly to minimize the rms distance, we can compute a rigid motion of B and a matching in O((n 4 /ε 5/2)log 6 n) time whose cost is within (1 + ε) factor of the optimal one
A 23.8–30.4-GHz Vector-Modulated Phase Shifter With Two-Stage Current-Reused Variable-Gain Amplifiers Achieving 0.23° Minimum RMS Phase Error
No full textThis letter presents a millimeter-wave (mm-wave) vector-modulated phase shifter (VMPS) for phased-array applications. To improve the phase-shift accuracy without drastically increasing design complexity, the proposed VMPS structure employs variable-gain amplifiers (VGAs) that offer 2× better resolution at their low-gain states compared to their high-gain states. A two-stage current-reused structure is also proposed to implement the desired VGAs with minimal layout complexity, negligible gain penalty, and no extra power. Moreover, the proposed VMPS can maintain its phase-shift accuracy even at lower voltage gains. Fabricated in 40-nm CMOS, the prototype core consumes 11 mW from a 1.1-V supply and occupies a core area of 0.19 mm2. At 28 GHz, with a phase resolution of 0.61°, the measured RMS phase error is 0.23° at the maximum gain and remains <0.5∘ at 9-dB gain back-off. With a fixed set of VGA’s codewords, the RMS phase error and gain variation error are, respectively, lower than 1° and 0.24-dB over a bandwidth of 23.8–30.4 GHz.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Electronic
An Algorithm for Calculating the RMS Value of the Non-Sinusoidal Current Used in AC Resistance Spot Welding
No full text
In this paper, an algorithm based on a model analysis of the online calculation of the root-mean-square (RMS) value of welding current for single-phase AC resistance spot welding (RSW) was developed. The current is highly nonlinear and typically non-sinusoidal, which makes the measuring and controlling actions difficult. Though some previous methods focused on this issue, they were so complex that they could not be effectively used in general cases. The electrical model of a single-phase AC RSW was analyzed, and then an algorithm for online calculation of the RMS value of the welding current was presented. The description includes two parts, a model-dependent part and a model-independent part. Using a previous work about online measurement of the power factor angle, the first part can be solved. For the second part, although the solution of the governing equation can be directly obtained, a lot of CPU time must be consumed due to the fact that it involves a lot of complex calculations. Therefore, a neural network was employed to simplify the calculations. Finally, experimental results and a corresponding analysis showed that the proposed algorithm can obtain the RMS values with a high precision while consuming less time when compared to directly solving the equations.</p
Uncertainty of a RMS Power Detector
No full textThe accuracy of a true-RMS detector board based on the Analog Devices LTC5596 is determined by measuring the input power and the output voltage. A number of samples of the output voltage is taken and the mean and standard deviation is shown. These measurements are done for single-tone excitation with a direct connection and over-the-air setup, and for multi-tone excitation with a direct connection. It has been demonstrated that the detector response worsens with over-the-air excitation, resulting in a doubling of the standard deviation in the output voltage compared to a direct connection. With multi-tone excitation, the standard deviation is fifteen times higher than with a direct connection. Additionally, with multi-tone excitation the mean output voltage is lower than with the same input power as single-tone. This discrepancy increases with the amount of tones.A Keysight Advanced Design System simulation is also presented for the three different measurement setups. With the use of a Monte Carlo simulation uncertainty bounds between the function generator and the power detector are made. Furthermore the noise of the power detector is simulated and sources of noise analyzed
Prozessmodellierung von Reaktiv-Multischicht-Systemen (RMS)
No full textDer Schwerpunkt der vorliegenden Arbeit ist die theoretische und experimentelle Beschreibung von sogenannten Reaktiv-Multischicht-Systemen (RMS).Die RMS bestehen aus mindesten zwei meist metallischen Materialien, die exotherm miteinander in Reaktion treten können. Mittels Magnetronsputter-Deposition(MSD) werden einige hundert bis mehrere tausend alternierende Einzelschichten hergestellt. Die Periodendicke variert zwischen 10-150 nm und die Gesamtdicke zwischen 10-100 mm. Dieexotherme chemische Reaktion wird durch eine Aktivierungsenergie, z.B. mit einem elektrischen Abrissfunken gestartet. Hierbei findet ein Phasenübergang der sich im metastabilen Gleichgewicht befindlichen RMS-Materialien statt. Dadurch wird Energie in Form von Wärme freigesetzt, welche in Nachbarbereichen wieder die Reaktion aktiviert. Es bildet sich eine selbsterhaltende thermische Welle durch die RMS-Folie aus. Hierbei ist soviel Energie vorhanden, dass ein sich auf der RMS und dem zu fügenden Bauteil befindliches Lot bzw. der Grundwerkstoff selbst aufgeschmolzen werden kann. Die RMS ist somit als Wärmequelle zum Verbinden von zwei Bauteilen einsetzbar. Der große Vorteildieser Technologie ist der sehr geringe Wärmeeintrag in die zu fügenden Bauteile aufgrund der sich innerhalb weniger Millisekunden abspielenden Reaktion. Dadurch werden die Bauteile nur oberflächlich erwärmt und es tritt keine Gefügeschädigung auf. So ist ebenfalls ein sehr spannungsarmes Fügen möglich. Außerdem ist durch die metallischen Materialien eine hohe elektrische und thermische Leitfähigkeit gewährleistet. Zur Charakterisierung werden Simulationen der physikalischen und chemischen Vorgänge innerhalb der RMS durchgeführt, um aus den Temperatur-Zeit-Verläufen die maximale Temperatur und Ausbreitungsgeschwindigkeit berechnen zu können. Zur Berechnung der Temperaturausbreitung in Bauteilen wird eine neue Methode vorgestellt. Damit ist es möglich die Eindringtiefe der Temperatur in Bauteile, Wärmebarriereschichtdicken und Schmelzzeiten zu bestimmen und so Parameter für das spezielle Fügeproblem, wie Periodendicke etc. der RMS abzuleiten. Durch Modellierung des Wärmetransports nach der Fügung von Bauteilen mittels RMS wird eine Korrelation zwischen thermischer Leitfähigkeit und Scherzugfestigkeit abgeleitet. Um die theoretischen Ergebnisse zu quantifizieren und bestimmte Parameter die in den Berechnungen notwendig sind zu erlangen, wurden Experimente durchgeführt. Die RMS werden hinsichtlich ihrer Enthalpie H, Ausbreitungsgeschwindigkeit v, freiwerdenden Temperatur, Interdiffusionszone w, Phasenumwandlung und dem Einsatz als innovative Wärmequelle zum Löten von Bauteilen experimentell untersucht. Diese Ergebnisse werden mit den Simulationen verglichen und runden die Arbeit ab.The focus of this work is the theoretical and experimentell descreption of so-called ReactiveMultilayer Systems (RMS).The RMS consist of at least two mostly metallic materials, which can exothermic response with each other. Using magnetron sputter deposition (MSD) several hundred to thousands alternating layers are produced. The periodic thickness varies between 10-150 nm and the total thickness between 10-100 mm. The exotermic reaction is effected by an activation energy, e.g. with an electric spark. In this case a phase transition of the RMS materials, which are in a metastable equilibrium, will take place. This released energy in the shape of heat, which actvates the reaction in the neighboring areas. It forms a self-sustaining thermal wave through the RMS foil. In this case the amount of energy is present, that a solder on the RMS or the joining samples or even the material itself can be melted. Therefore the RMS can be used as a heat source for joining two components. The major advantage of this technology is the very low heat input in the bonding components, due to the milliseconds of the reaction. Thus the components are heated only superfical and there is no structural damage. Thus a very low-stress joining is possible. Furthermore is guaranteed, because of the metallic materials, a very high electrical and thermal conductivity. For the theoretical characterization of the physical and chemical processes within the RMSFEM-Simulations of the absolut temperature and the propagation velocity are preformed. In order to calculate the tmeperature ditribution in the components a new method will presented. It is thus possible to calculate the temperature penetration of the components to determine potential thermal barrier layer-thickness and the meltig time. Thus parameters for the specific joint problem such as period thickness, etc. of the RMS are derived. Modelling the heat transport after joining with RMS it is possible to derive a correlation between the thermal conductivity and shear strength. To quantify the theoretical results and to require certain parameters for the calculations experiments were preformed. The RMS will be investigated experimentally in terms of their enthalpy H, propagation velocity v, nascent temperature, melting time tschmelz, interdiffusion zone w, phase transition and its use as inovative heat source for joining components. The experimental results are compared with the theortical and complet this work.1 Einleitung // 2 Stand der Technik // 2.1 Geschichtliche Entwicklung // 2.2 Prinzipeller Aufbau von Reaktiv-Multischicht-Systemen (RMS) // 2.3 Ausgewählte Reaktiv-Multischicht-Systeme // 2.4 Herstellung von Reaktiv-Multischicht-Systemen (RMS) // 2.4.1 Kaltwalzen // 2.4.2 Galvanische Abscheidung // 2.4.3 Magnetronsputter-Deposition // 2.5 Anwendung von Reaktiv-Multischicht-Systemen // 2.6 Zusammenfassung und Neuerungen in dieser Arbeit // 3 Grundlagen // 3.1 Entwicklung von Modellen zur Beschreibung von RMS und deren Anwendung // 3.1.1 Weiterentwicklung eines Modells zur Beschreibung der physikalischen und chemischen Vorgänge innerhalb der RMS // 3.1.2 Entwicklung eines Modells zur Bestimmung des Wärmeeintrags in Bauteile beim Fügen mit RMS // 3.1.3 Entwicklung eines Modells zur Berechnung der effektiven Verbindungsfläche von Fügung mit RMS // 3.2 Herstellung von Reaktiv-Multischicht-Systemen // 3.3 Beschreibung der Werkzeuge zur Bestimmung wichtiger Größen von RMS // 3.3.1 Transmissionselektronenmikroskopie (TEM) // 3.3.2 Rasterelektronenmikroskopie (REM) // 3.3.3 Phasenanalyse von RMS mit Synchrotronstrahlung // 3.3.4 Differenzthermoanalyse (DTA) // 3.3.5 Messung der Ausbreitungsgeschwindigkeit // 3.3.6 Temperaturmessung mit zeitlich hochaufgelöstem Pyrometer // 3.4 Beschreibung der Durchführung von Fügungen mit RMS // 3.4.1 Herstellung von RMS-Lötungen // 3.4.2 Vorbelotung // 3.4.3 Vorbehandlung der Proben // 3.4.4 Messung des spezifischenWiderstandes // 3.4.5 Temperaturwechseltest // 4 Ergebnisse und Diskussion // 4.1 Modellierung von Reaktiv-Multischicht-Systemen (RMS) // 4.1.1 Modellierung der physikalischen und chemischen Vorgänge der RMS // 4.1.2 Modellierung von RMS-Fügung // 4.1.3 Modellierung der effektiven Verbindungsfläche // 4.2 Experimentelle Bestimmung der Eigenschaften von RMS // 4.2.1 Analyse mit Transmissions- und Rasterelektronenmikroskopie // 4.2.2 Phasenanalyse mittels Röntgendiffraktometrie // 4.2.3 Ergebnisse der Differenzthermoanalyse // 4.2.4 Ausbreitungsgeschwindigkeit der selbsterhaltenden Reaktion // 4.2.5 Messung des Temperaturfeldes // 5 Anwendung von Reaktiv-Multischicht-Systemen (RMS) // 5.1 Cu-Cu- und Al-Al-Fügungen mit Sn-Weichlot // 5.1.1 Variation des Fügedrucks // 5.1.2 Variation der Sn-Barriereschichtdicke // 5.1.3 Variation der Proben-Temperatur und der Gesamtdicke der RMS // 5.2 Al-Cu-Proben mit Incusil-Hartlot // 5.3 Messung des spezifischenWiderstandes // 5.3.1 Vergleich der Leitfähigkeit bei Fügungen // 5.3.2 Variation der Belotung und der Gesamtdicke der RMS // 5.3.3 Variation des atomaren Verhältnisses der RMS // 5.3.4 Variation der Sn-Barrierenschichtdicke // 5.3.5 Zusammenfassung // 6 Schluss und Ausblic
Static and dynamic aspects of the rms local slope of growing random surfaces
No full textIn this work, we investigated static and dynamic aspects of the rms local surface slope ‘‘ρ’’ for self-affine random surfaces. The rms local slope is expressed as a function of the rms roughness amplitude σ, the in-plane correlation length ξ, and the roughness exponent H (0<H<1), as well as is shown to scale as ρ~σξ^-H. Application to room temperature heteroepitaxial silver films shows the rms local slope to be closely time invariant in the thickness range 10<h<1000 nm with an asymptotic value ρ≈0.7. However, discrepancies in deposition details could alter the mode of film growth leading to a power law growth of the local slope as a function of the film thickness h; ρ∝h^c (c>0).
Skin-Friction Measurements on Mathematically Generated Roughness in a Turbulent Channel Flow
No full textEngineering systems are affected by surface roughness, however, predicting frictional drag has proven to be challenging. The present work takes a systematic approach by generating and manufacturing surfaces roughness where surface statistics, such as rms, skewness and power-spectral density can be controlled. The frictional drag on these surfaces is measured in a turbulent channel flow facility
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