Results 1 - 10 of 3264
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[en] The ATLAS ReadOut System (ROS) receives data fragments from ∼1600 detector readout links, buffers them and provides them on demand to the second-level trigger or to the event building system. The ROS is implemented with ∼150PCs. Each PC houses a few, typically 4, custom-built PCI boards (ROBIN) and a 4-port PCIe Gigabit Ethernet NIC. The PCs run a multi-threaded object-oriented application managing the requests for data retrieval and for data deletion coming through the NIC, and the collection and output of data from the ROBINs. At a nominal event fragment arrival rate of 75 kHz the ROS has to concurrently service up to approximately 20 kHz of data requests from the second-level trigger and up to 3.5 kHz of requests from event building nodes. The full system has been commissioned in 2007. Performance of the system in terms of stability and reliability, results of laboratory rate capability measurements and upgrade scenarios are discussed in this paper.
[en] Analysis of scattered Lamb waves in thin plates and shells, with an added foreign mass on their surface, was performed. Waves were generated in a range of frequencies, up to 80 kHz, by an impact loading. The responses were detected by full-field and point-wise optical methods. Pulse holointerferometry and pulse electronic speckle patterns interferometry techniques were used to visualize the interaction of the Lamb waves with the added foreign mass. Double-channel laser vibrometry was used to record the velocity history within the proximity of the added foreign mass. It was shown that frequency analysis of the recorded waveforms was more convenient than time domain analysis when investigating the response in the thin-walled structures. The proposed method is applicable to search for suspicious masses (e.g. explosive devices) added to the structures.
[en] A Josephson arbitrary waveform synthesizer (JAWS) has been used for the synthesis of bipolar waveform voltage signals. The two major changes with respect to earlier work are the use of Josephson arrays consisting of more junctions and the use of a new type of pattern generator. With a multi-branch Josephson array from IPHT, the synthesized sinusoidal voltages have amplitudes up to 9.5 mV zero to peak and frequencies in the range from 100 Hz to 150 kHz. For instance, for a 9.5 mV sine wave of 122 kHz, the spectrum of the synthesized signal shows that higher harmonics are at least 86 dB below the fundamental. Comparable suppression was achieved with a single-branch Josephson array from PTB generating a 17 mV sine wave of 180 Hz. Additionally, with a PTB array, sinusoidal signals with amplitudes up to 57 mV zero to peak are generated with higher harmonics typically 60 dB to 70 dB below the fundamental at frequencies below a few hundred hertz
[en] This paper presents a method of numerical simulation that makes it possible to calculate the induced tension to the terminals of the cardiac pacemaker subjected to conduced disturbances. The physical model used for simulation is an experimental test bed which makes it possible to study the behaviour of pacemaker, in vitro, subjected to electromagnetic disturbances in low frequencies range (50 hz - 500 khz). The test bed in which the pacemaker is implanted is described in this article. The process of calculation uses the admittance method adapted to the case of conducted disturbances. Results obtained by numerical simulation are close to experimental values. (authors)
[en] An array of miniature size plasma jet generators might become an important tool for surface processing especially if the minijet plasma generator can operate at atmospheric pressures. Our efforts started with the design and construction of a d.c. miniature plasma jet generator but components' heating and unstable operation excluded this solution and imposed its change. In the present paper we report a successful development of an a.c. operated miniature type plasma jet generator. The frequency of the applied a.c. voltage was around 10 kHz, the value of the peak to peak voltages being up to 700 V for nitrogen gas at atmospheric pressure. The obtained time dependence of the discharge current and voltage drop over the discharge space, prove that the discharge was not of barrier type but an alternating d.c. type discharge with the mentioned frequency. The measured discharge current was of 55 mA, the measured power value being of the order of a few watts. It is important to mention that the gas flux is passing through a central hole of 0.5 mm diameter of the minijet generator, the obtained jet being very stable and operating hours without failure. In the case of an array of such minijets, due to radial expansion of plasma minijets after going out of hole, at a few millimeter distance, the jets will unite, building up a large area of uniform plasma, ideal for surface treatment at low plasma temperature. (authors)
[en] This paper reports an experimental study of a plasma jet by using optical measurement and spectroscopic method. The plasma jet, composed of an inner electrode with a sharpen end and an outer water-electrode, has a cross-field configuration. A cross-field mode of the plasma jet is realized when the applied voltage is low. However, a different mechanism of plasma plume generation is involved when the applied voltage is high enough, and a linear-field mode of the plasma jet can be realized. The two different modes of the plasma jet are compared by spectroscopic method and results show that electron energy in linear-filed mode is higher than that in cross-field mode.
[en] This paper presents a unique CMOS linear image sensor for reading the pseudo-random code on the slit disc, focusing on the two aspects of low noise and readout rate. Each pixel is equipped with an exclusive integral readout circuit, and the shape of the pixel also matches the slit disc, making the output signal consistent by up to 99%. After subdivision, the absolute angle data can be captured with an angular resolution of 16 bits and a maximum speed of 7.4 kHz. In addition, decoding and subdivision methods are suitable for high-speed, inexpensive encoder systems.
[en] The ATLAS readout subsystem is the main interface between ∼ 1600 detector front-end readout links and the higher-level trigger farms. To handle the high event rate (up to 100 kHz) and bandwidth (up to 160 MB/s per link) the readout PCs are equipped with four ROBIN (readout buffer input) cards. Each ROBIN attaches to three optical links, provides local event buffering for approximately 300 ms and communicates with the higher-level trigger system for data and delete requests. According to the ATLAS baseline architecture this communication runs via the PCI bus of the host PC. In addition, each ROBIN provides a private Gigabit Ethernet port which can be used for the same purpose. Operational monitoring is performed via PCI. This paper presents a summary of the ROBIN hardware and software together with measurements results obtained from various test setups