257 research outputs found
Studying the Degradation of Propagation Delay on FPGAs at the European XFEL
No full textAn increasing number of unhardened commercial-off-the-shelf embedded devices are deployed under harsh operating conditions and in highly-dependable systems. Due to the mechanisms of hardware degradation that affect these devices, ageing detection and monitoring are crucial to prevent critical failures. In this paper, we empirically study the propagation delay of 298 naturally-aged FPGA devices that are deployed in the European XFEL particle accelerator. Based on in-field measurements, we find that operational devices show significantly slower switching frequencies than unused chips, and that increased gamma and neutron radiation doses correlate with increased hardware degradation. Furthermore, we demonstrate the feasibility of developing machine learning models that estimate the switching frequencies of the devices based on historical and environmental data.If you cite this paper, please use the DSD reference: Leandro Lanzieri, Lukasz Butkowski, Jiri Kral, Goerschwin Fey, Holger Schlarb, and Thomas C. Schmidt. Studying the Degradation of Propagation Delay on FPGAs at the European XFEL. In Proceedings of the 27th Euromicro Conference on Digital System Design (DSD), IEEE, 202
Hotspots of academic misconduct and misrepresentations among academics in the Republic of Poland, a European Union member state
No full textAcademic misconduct, misrepresentations, and gaming are a set of variable malpractices eroding public trust in scientific achievements and institutions of higher education. Here, the author analysed data on academic misconduct and misrepresentations in the Republic of Poland. The results presented here have based on the analysis of the records on academic malpractices revealed to the public by professor Marek Wronski, writing in the Academic Forum magazine regularly about academic integrity in Poland. Three or more examples of academic malpractices conducted by scholars working in the same institution of higher education cannot be explained by coincidence. Hence, an analysis of Marek Wronski's writing on academic integrity has revealed the existence of the hotspots of academic misconduct and misrepresentations in the Polish institutions of higher education. In addition, the Science Ethics Committee of the Polish Academy of Science, the Disciplinary Committee at the Central Council of Science and Higher Education, the Ministry of Education and Science, and the Council of Scientific Excellence have been asked to provide data on academics accused of misconduct. Moreover, Polish institutions responsible for investigating allegations of academic misconduct and misrepresentation be reluctant to disclose information about academics accused of misconduct and misrepresentation. Data presented in that paper may suggest the organisational research climate in the Polish institutions of higher education, and research may favour academic malpractices
Agents of seed dispersal : animal--zoochary / Wind--anemonochory
No full textThesis (S.M.)--Massachusetts Institute of Technology, Dept. of Architecture, 2004.Includes bibliographical references (leaves 91-98).Agents of seed dispersal is a project designed to address the increase of environmental degradation, which occurs as a result of the perpetual spread of the asphalt and concrete of the contemporary urban situation. Agents of Seed Dispersal proposes that the city is a natural ecosystem within the greater context of earth's environment. The city as an ecosystem challenges the common notion that the urban setting is artificial and the environment outside of its boundaries is the sole representation of nature. The metropolis as an ecosystem requires that earth's occupants address it as a natural system and as an ecosystem it requires environmental thought and action. Through the Agents of Seed Dispersal project the author initiates two separate but corresponding projects, which focus on urban environmental degradation by reversing the spread of the asphalt surface and it's corresponding suffocation of plant life by propagating the distribution and growth of specific plant life within the city.by Lukasz Kamil Lysakowski.S.M
A Model Based Fast Protection System for High Power RF Tube Amplifiers Used at the European XFEL Accelerator
No full textThe driving engine of the superconducting accelerator of the European X-ray free electron laser (XFEL) is a set of 27 radio frequency (RF) stations. Each of the underground RF stations consists of a multibeam horizontal klystron that can provide up to 10 MW of power at 1.3 GHz. Klystrons are sensitive devices with a limited lifetime and a high mean time between failures. In real operation, the lifetime of the tube can be significantly reduced because of failures. The special fast protection klystron lifetime management (KLM) system has been developed to minimize the influence of service conditions on the lifetime of klystrons. The main task of this system is to detect all events which can destroy the tube as quickly as possible, and switch off the driving RF signal or the high voltage. Detection of events is based on a comparison of the value of the real signal obtained at the system output with the value estimated on the basis of a high-power RF amplifier model and input signals. The KLM system has been realized in field-programmable gate array (FPGA) and implemented in XFEL. Implementation is based on the standard low-level RF micro telecommunications computing architecture (MTCA.4 or xTCA). The main part of the paper focuses on an estimation of the klystron model and the implementation of KLM in FPGA. The results of the performance of the KLM system will also be presented
Shear capacity of steel fibre reinforced concrete beams
No full textThe Critical Shear Displacement Theory (CSDT) was developed to determine the shear capacity of reinforced concrete beams based on the different shear-carrying mechanisms (concrete in the compression zone, aggregate interlock, and dowel action). This research aims at extending the CSDT to Steel Fibre Reinforced Concrete (SFRC) by adding the contribution of steel fibres. The model extension was developed based on formulations for the contribution of steel fibres to the shear capacity from the literature. With this extension to the CSDT, the shear strength of steel fibre reinforced concrete beams without stirrups could be estimated. An extensive database is developed from the literature in order to evaluate, compare, and analyse the shear capacity of SFRC beams. The analysis indicates that two models are capable of predicting the shear strength of SFRC beams with reasonable accuracy. The mean, standard deviation, and coefficient of variation are 0.9, 0.28, 0.31 and 1.1, 0.33 and 0.30 respectively. The main geometric variables of the steel fibres that influenced the shear strength are the length, diameter, and fibre type (hooked, crimped, and straight). From the comparison between the results in the database and the proposed extensions to the CSDT it is found that the critical shear displacement of Δcr = 0.025 mm, gives reasonable results for SFRC. As such, this proposed method can be used to estimate the shear strength of SDRC based on a mechanical model.Accepted Author ManuscriptConcrete Structure
The Self Excited Loop Cavity Field Controller and the Cavity Simulator Implemented in MTCA.4 System
No full textThe superconducting cavity vertical test stand at DESY is going to be updated with the MTCA.4 based system. The digital self exited loop (SEL) LLRF controller has been developed to fulfill the requirements for the controller to drive the cavity with high QL up to 1e10 and high cavity detuning up to 10kHz. In order to test the SEL controller, additionally the real-time cavity simulator has been developed. The electrical and mechanical model of a cavity represented by a differential equation, is implemented inside the FPGA. The model takes the forward power as an input and produces a probe signal based on given detuning and half-bandwidth parameters of a cavity. Microphonic disturbance is also added to simulate the high Ql operation.Both, the cavity simulator and the SEL controller has been implemented in the SIS8300KU, DRTM-DW8VM1 pair boards
Motion Control Strategies for Smart Floating Cranes
No full textFloating structures have raised interest in the recent years for different applications, from living and farming at sea to renewable energy production. To support the logistics on the floating structures, floating cranes are necessary and their designs are constantly improved. Increasing developments in the automation industry paved the way for automated crane operations. In this work, motion control of a smart crane is presented with particular attention to the performance under wave motion. In this research, a scaled down, two-dimensional mathematical model of a gantry crane is derived using Lagrangian mechanics and DC motors dynamics. This results in a nonlinear system that is capable of simultaneous traversing and hoisting a container. The system is simulated in MATLAB Simulink environment and a proportional-derivative control and a state feedback control are designed and implemented. Their robustness is explored by modelling sensor behavior, external disturbances and floating platform dynamics. Both control strategies were able to keep stability in a disturbed system. During simulation, the sway angles never exceed 10°. Smaller oscillations occurred using the state feedback control. Therefore, it creates a smoother response compared to the proportional derivative control, which ultimately translates to increased safety, turnover rate and durability of the crane.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.Transport Engineering and Logistic
Klystron Measurement and Protection System for XFEL on the uTCA Architecture
No full textThe European XFEL free-electron laser is under construction at the DESY. The driving engineof the superconducting accelerator will be 27 RF station. Each of an underground RF stationconsist from multi beam horizontal klystron which can provide up to 10MW of power at1.3GHz. The XFEL should work continuously over 20 years with only 1 day per month formaintenance. In order to meet so demanding requirement lifetime of the MBK should be aslong as possible. In the real operation the lifetime of tube can be thoroughly reduced by serviceconditions. To minimize the influence of service conditions to the klystrons lifetime thespecial fast protection system named as Klystron Lifetime Management System (KLM) hasbeen developed, the main task of this system is to detect all events which can destroy thetube as quickly as possible, and then stop input power to the tube and send signal to stopHV pulse. The tube recovery procedure should depend on the kind of events has happened.KLM is based on the standard LLRF uTCA system for XFEL with additional DC channels.This article gives an overview of implementation of measurement and protection systeminstalled at klystron test stand
Motion control strategies for smart floating cranes
No full textFloating structures have raised interest in the recent years for different applications, from living and farming at sea to renewable energy production. To support the logistics on the float- ing structures, floating cranes are necessary and their designs are constantly improved. In- creasing developments in the automation industry paved the way for automated crane opera- tions. In this work, motion control of a smart crane is presented with particular attention to the performance under wave motion. In this research, a scaled down, two-dimensional math- ematical model of a gantry crane is derived using Lagrangian mechanics and DC motors dy- namics. This results in a nonlinear system that is capable of simultaneous traversing and hoist- ing a container. The system is simulated in MATLAB Simulink environment and a proportional-derivative control and a state feedback control are designed and implemented. Their robustness is explored by modelling sensor behavior, external disturbances and floating platform dynamics. Both control strategies were able to keep stability in a disturbed system. During simulation, the sway angles never exceed 10 degrees. Smaller oscillations occurred us- ing the state feedback control. Therefore, it creates a smoother response compared to the pro- portional derivative control, which ultimately translates to increased safety, turnover rate and durability of the crane.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.Transport Engineering and Logistic
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