19,249 research outputs found
Jitter and Decision-level Noise Separation in A/D Converters
Gaussian aperture jitter leads to a reduced SNR of A/D converters. Also other noise sources, faults and nonlinearities affect the digital output signal. A measurement setup for a new off-chip diagnosis method, which systematically separates the jitter-induced errors from the errors caused by these other factors, is described. Deterministic errors are removed via a subtracting technique. High-level ADC simulations and measurements have been carried out to determine relations between the size of the jitter or decision-level noise and the remaining random errors. By carrying out two tests at two different input frequencies and using the simulation results, errors induced by decision-level noise can be remove
Power Converters and Power Quality
This paper discusses the subject of power quality for power converters. The
first part gives an overview of most of the common disturbances and power
quality issues in electrical networks for particle accelerators, and explains
their consequences for accelerator operation. The propagation of asymmetrical
network disturbances into a network is analysed. Quantitative parameters for
network disturbances in a typical network are presented, and immunity levels
for users' electrical equipment are proposed. The second part of this paper
discusses the technologies and strategies used in particle accelerator networks
for power quality improvement. Particular focus is given to networks supplying
loads with cycling active and reactive power.Comment: 26 pages, contribution to the 2014 CAS - CERN Accelerator School:
Power Converters, Baden, Switzerland, 7-14 May 201
QoS multicast tree construction in IP/DWDM optical internet by bio-inspired algorithms
Copyright @ Elsevier Ltd. All rights reserved.In this paper, two bio-inspired Quality of Service (QoS) multicast algorithms are proposed in IP over dense wavelength division multiplexing (DWDM) optical Internet. Given a QoS multicast request and the delay interval required by the application, both algorithms are able to find a flexible QoS-based cost suboptimal routing tree. They first construct the multicast trees based on ant colony optimization and artificial immune algorithm, respectively. Then a dedicated wavelength assignment algorithm is proposed to assign wavelengths to the trees aiming to minimize the delay of the wavelength conversion. In both algorithms, multicast routing and wavelength assignment are integrated into a single process. Therefore, they can find the multicast trees on which the least wavelength conversion delay is achieved. Load balance is also considered in both algorithms. Simulation results show that these two bio-inspired algorithms can construct high performance QoS routing trees for multicast applications in IP/DWDM optical Internet.This work was supported in part ny the Program for New Century Excellent Talents in University, the Engineering and Physical Sciences Research Council (EPSRC) of UK under Grant EP/E060722/1, the National Natural Science Foundation of China under Grant no. 60673159 and 70671020, the National High-Tech Reasearch and Development Plan of China under Grant no. 2007AA041201, and the Specialized Research Fund for the Doctoral Program of Higher Education under Grant no. 20070145017
The OpenPicoAmp : an open-source planar lipid bilayer amplifier for hands-on learning of neuroscience
Neuroscience education can be promoted by the availability of low cost and
engaging teaching materials. To address this issue, we developed an open-source
lipid bilayer amplifier, the OpenPicoAmp, which is appropriate for use in
introductory courses in biophysics or neurosciences dealing with the electrical
properties of the cell membrane. The amplifier is designed using the common
lithographic printed circuit board fabrication process and off-the-shelf
electronic components. In addition, we propose a specific design for
experimental chambers allowing the insertion of a commercially available
polytetrafluoroethylene film. This experimental setup can be used in simple
experiments in which students monitor the bilayer formation by capacitance
measurement and record unitary currents produced by ionic channels like
gramicidin A. Used in combination with a low-cost data acquisition board this
system provides a complete solution for hands-on lessons, therefore improving
the effectiveness in teaching basic neurosciences or biophysics.Comment: 13 pages, 6 figures and supplementary information (9 files including
one movie). Added references, added figure, corrected typos, corrected board
components list, more detailled implementation documen
Narrative music: towards an understanding of musical narrative functions in multimedia
As the computer screen is replacing the book as the dominant medium for communication (Kress, 2003), questions about how meaning is constituted by the multimodal interaction of different media (including music) is becoming increasingly important in contemporary research of pedagogy, sociology and media studies. The overall aim with this licentiate thesis is to explore musical narrative functions as they appear in multimedia such as film and computer games.
The thesis is based on three publications. Publication 1 proposes a classification of musical narrative functions, with 6 narrative classes(the Emotive, Informative, Descriptive, Guiding, Temporal and Rhetorical classes) and 11 categories. The relational interplay of music with contextual factors is emphasized.
Publication 2 describes the design of a software tool, REMUPP (Relations Between Musical Parameters and Perceived Properties), to be used for experimental studies of musical expression. REMUPP is used for real time alteration of musical expression, by the manipulation of musical parameters such as tempo, harmony, rhythm, articulation, etc.
Publication 3 describes a quasi-experiment using REMUPP, where a group of young participants (12-13 years old) were given the task of adapting musical expression – by manipulating 7 parameters – to make it fit 3 visual scenes shown on a computer screen. They also answered a questionnaire asking about their musical backgrounds and habits of listening to music, watching movies and playing computer games. Numerical data from the manipulations were analyzed statistically with regards to the preferred values of the musical parameters in relation to the different visual scenes. The results indicated awareness and knowledge about codes and conventions of musical narrative functions, and were to some degree affected by the participants’ gender, musical backgrounds and media habits
Modular multilevel converter losses model for HVdc applications
Multi-terminal high voltage dc (HVdc) grids can eventually became a feasible solution to transport energy to remote and/ or distant areas and its exploitation depend, among other things, on the performance of the converter terminals. Therefore, to optimize the power transmission strategy along such a grid, it is necessary to recognize the efficiency of all the converters in all points of operation, namely with the different load conditions. In this vision, the aim of this work is to provide the methodology to model the modular multilevel converter (MMC) efficiency by means of a mathematical expression that can describe, over a broad range of active and reactive power flow combinations, the power losses generated by the semiconductors. According to the presented methodology, a polynomial-based model with a reduced number of coefficients is deducted, in such a way that can be directly used for optimal power flow (OPF) studies. The accuracy of the proposed model is characterized by an absolute relative error, at the worst scenario, approximately equal to 3%.Postprint (author's final draft
Tactical communication systems based on civil standards: Modeling in the MiXiM framework
In this paper, new work is presented belonging to an ongoing study, which
evaluates civil communication standards as potential candidates for the future
military Wide Band Waveforms (WBWFs). After an evaluation process of possible
candidates presented in [2], the selection process in [1] showed that the IEEE
802.11n OFDM could be a possible military WBWF candidate, but it should be
further investigated first in order to enhance or even replace critical
modules. According to this, some critical modules of the physical layer has
been further analyzed in [3] regarding the susceptibility of the OFDM signal
under jammer influences. However, the critical modules of the MAC layer (e.g.,
probabilistic medium access CSMA/CA) have not been analysed. In fact, it was
only suggested in [2] to replace this medium access by the better suited
Unified Slot Allocation Protocol - Multiple Access (USAP-MA) [4]. In this
regard, the present contribution describes the design paradigms of the new MAC
layer and explains how the proposed WBWF candidate has been modelled within the
MiXiM Framework of the OMNeT++ simulator.Comment: Published in: A. F\"orster, C. Sommer, T. Steinbach, M. W\"ahlisch
(Eds.), Proc. of 1st OMNeT++ Community Summit, Hamburg, Germany, September 2,
2014, arXiv:1409.0093, 201
- …