Abstract
The ATLAS detector is set to undergo a substantial upgrade
termed the “Phase-II” upgrade during the Long-Shutdown in
preparation for the start of operation of the High Luminosity Large
...Hadron Collider (HL-LHC). This paper describes the development and
implementation of the Phase-II upgrade low voltage power supply
transformer-coupled buck converter (Brick) test bench. A large
scale production of approximately 2048 finger low voltage power
supplies, with an identical output voltage, is set to be undertaken
in the year 2022. This production will culminate in the complete
replacement of the LVPS Brick V7.5.0 currently installed within the
Tile Calorimeter. Due to the location of the Bricks within the inner
barrel of the TileCal their reliability is of the utmost
importance. Therefore, the implementation of performance screening
will be implemented and will involve the testing and certification
of all Bricks produced. A custom test bench has been developed in
order to facilitate the above-mentioned testing. The test bench
described herein quantifies and logs the performance of an upgrade
Brick allowing for comparison with predefined performance metrics
before being approved and subsequently installed on-detector.
High power diode laser remelting of metals Chmelickova, H; Tomastik, J; Ctvrtlik, R ...
Journal of physics. Conference series,
01/2014, Letnik:
497, Številka:
1
Journal Article
Recenzirano
Odprti dostop
This article is focused on the laser surface remelting of the steel samples with predefined overlapping of the laser spots. The goal of our experimental work was to evaluate microstructure and ...hardness both in overlapped zone and single pass ones for three kinds of ferrous metals with different content of carbon, cast iron, non-alloy structural steel and tool steel. High power fibre coupled diode laser Laserline LDF 3600-100 was used with robotic guided processing head equipped by the laser beam homogenizer that creates rectangular beam shape with uniform intensity distribution. Each sample was treated with identical process parameters - laser power, beam diameter, focus position, speed of motion and 40% spot overlap. Dimensions and structures of the remelted zone, zone of the partial melting, heat affected zone and base material were detected and measured by means of laser scanning and optical microscopes. Hardness progress in the vertical axis of the overlapped zone from remelted surface layer to base material was measured and compared with the hardness of the single spots. The most hardness growth was found for cast iron, the least for structural steel. Experiment results will be used to processing parameters optimization for each tested material separately.
This research provides an attempt to achieve uniform grain structure by recrystallization process in NiMoCr alloy after different hot- and cold-working application. The changes in microstructure ...resulting from thermomechanical processing were investigated by optical microscopy. The results showed that homogeneity of the recrystallized structure is strongly related to the amount of sample reduction imposed during hot working and to the period of annealing time. Furthermore, the results illustrate that the recrystallized structure at the surface was finer, than in the interior of the sample. This is due the specimen surface, which is more strain exposed for applied deformation and driving force for primary recrystalization in sample surface area is therefore higher than in central part of samples. Then, using conventional two-step hot rolling, the expected uniform recrystallized microstructure could not be obtained across the width of slab. An unfavourable contribution at recrystalization process was observed from initial grain size heterogeneity of as-cast ingot structure. However, after additional introduction of cold rolling, which followed hot working the more uniform recrystallized grain structure was achieved after recrystallization annealing.
This paper describes a new portable test bench for the TileCal sub-detector of the ATLAS experiment at CERN. The system is used for the certification and quality checks of the front-end electronics ...drawers. It is designed to be an easily upgradable version of the current 10-year-old system, able to evaluate the new technologies planned for the upgrade as well as provide new functionality to the present system. It will be used during the long shutdown of the LHC in 2013-14 and during future maintenance periods.
The ATLAS Detector Control System Lantzsch, K; Arfaoui, S; Franz, S ...
Journal of physics. Conference series,
01/2012, Letnik:
396, Številka:
1
Journal Article
Recenzirano
Odprti dostop
The ATLAS experiment is one of the multi-purpose experiments at the Large Hadron Collider (LHC) at CERN, constructed to study elementary particle interactions in collisions of high-energy proton ...beams. Twelve different sub detectors as well as the common experimental infrastructure are controlled and monitored by the Detector Control System (DCS) using a highly distributed system of 140 server machines running the industrial SCADA product PVSS. Higher level control system layers allow for automatic control procedures, efficient error recognition and handling, manage the communication with external systems such as the LHC controls, and provide a synchronization mechanism with the ATLAS data acquisition system. Different databases are used to store the online parameters of the experiment, replicate a subset used for physics reconstruction, and store the configuration parameters of the systems. This contribution describes the computing architecture and software tools to handle this complex and highly interconnected control system.
The class VI intermediate filament protein nestin has been generally considered as a specific marker for neural precursor cells or developing muscles. In the prenatal developing rat central nervous ...system (CNS), we localized immunoreactivity for the nestin in blood vessels. Although the widespread nestin expression in cerebral blood vessels persisted in early postnatal periods, it was down-regulated in the adulthood. However, when the adult rat brains were subjected to procedures that trigger neovascularization, e.g. grafting fetal nervous tissue or C6 glioma, the abundant immunoreactivity was detected in all newly formed vessels and adjacent host vasculature. Our results demonstrate that nestin expression in endothelial cells lining cerebral vessels accompanies the process of angiogenesis.
Abstract
Pressure vessels made of high-strength steels are usually welded by arc methods. The paper deals with the development of laser and electron thick-walled beam welding technology for the ...mentioned applications. The mechanical and structural properties of laser and electron beam welds of plates with a thickness of 5–20 mm are compared both with and without additional filling material. The study is completed with a detailed analysis of residual stresses and their relation not only to the used welding technology but also to the results in the weld area. Laser and electron beam welds achieve high mechanical values and sufficient fatigue life. Therefore, the technology has been verified and applied for welding the test pressure vessel.
PDF
