433 research outputs found
A study of fault diagnosis and recovery techniques for manufacturing systems
No full textThis chapter describes a framework for the development of a diagnosis methodology for industrial manufacturing systems. The aim of the project is to support technicians that supervise the manufacturing plant to identify the causes of faults and failures on the machine and, in particular, to indicate a procedure for the recovery of its working condition. The chapter presents a study as the first step of a design project whose objective is to realize a supervisory system with advanced features devoted to Faults Detection and Isolation (FDI) for the manufacturing industry, with an emphasis on its integration with Human-Machine Interfaces. The requirements described in the chapter are defined giving particular care to the peculiarities of the application domain to allow the design of a powerful, but easy to use for industrial technicians, diagnostic system. An example of a manufacturing machine quite common in the packaging industry is schematized in the chapter, which is analyzed to define the fault trees for the most critical failure modes. © 2007 Copyright © 2007 Elsevier Ltd All rights reserved
Flavor asymmetry of the polarized light sea: models vs. data
No full textAbstractThe flavor asymmetry of the polarized light sea, Δū−Δd̄, discriminates between different model calculations of helicity densities. We show that the chiral chromodielectric model, differently from models based on a 1/Nc expansion, predicts a small value for this asymmetry, what seems in agreement with preliminary HERMES data
Fuzzy Control Techniques Applied to Wind Turbine Systems and Hydroelectric Plants
No full textThe interest on the use of renewable energy resources is increasing, especially wind and hydro powers. To this aim, fuzzy control techniques represent viable strategies that can be employed for this purpose, thanks to the features of these nonlinear dynamic processes working over a wide range of operating conditions, driven by stochastic inputs, excitations and disturbances. Based on past investigations carried out by the authors about the control of wind turbines and hydroelectric power plants, this paper provides some guidelines on the design and application of the control strategies suitable to these energy conversion systems. The working conditions of these energy conversion systems are also taken into account to highlight the reliability and robustness characteristics of the developed control strategies
Hardware–In–The–Loop Assessment of Robust Fuzzy Control Solutions for Hydroelectric and Wind Turbine Models
No full textThe interest towards renewable energy resources is increasing, and in particular it concerns wind and hydro powers, where the key point regards their efficient conversion into electric energy. To this end, control techniques can be used to meet this purpose, especially the ones relying on fuzzy models, due to their capabilities to manage nonlinear dynamic processes working in different conditions, and affected by faults, measurement errors, uncertainty and disturbances. The design methods addressed in this paper were already developed and validated for wind turbine plants, and important results can be achieved from their appropriate design and application to hydroelectric plants. This is the key issue of the paper, which recalls some considerations on the proposed solutions, as well as their validation to these energy conversion systems. Note that works available in the related literature that consider both wind and hydraulic energy conversion systems investigate a limited number of common issues, thus leading to little exchange opportunities and reduced common research aspects. Another important point addressed in the paper is that the proposed control design solutions are able to take into account the different working conditions of these power plants. Moreover, faults, uncertainty, disturbance and model reality mismatch effects are also considered when analyzing the reliability and robustness features of the derived control schemes. To this end, proper hardware in the loop tools are considered to verify and validate the developed control schemes in more realistic environments. Copyright (C) 2022 The Authors
Control Strategy Applied to Smart Photovoltaic Inverters for Reactive Power Exchange Through Volt-Var Control to Improve Voltage Quality in Electrical Distribution Networks
No full textPhotovoltaic (PV) generation systems have become part of the electrical distribution networks due to their clean energy and adaptability. The increasing energy consumption and the several load types in the distribution network could produce voltage deviation. Therefore, there are some strategies, which are used to solve this problem, for example, capacitor banks, voltage regulators, transformer tap variation, static Var compensators, and reactive power exchange employing inverters. This article presents a smart inverter able to deliver and absorb reactive power through Volt-Var control to solve voltage deviations. The inverter compensates for voltage deviation in the primary transformer, whether inductive or capacitive loads are connected in the point of common coupling (PCC). In consequence, the inverter improves the voltage quality in the entire network. Finally, total harmonics percentage (THD) and frequency deviation have an acceptable performance during the operation, due to the inverter hardware configuration, and the phase-locked loop (PLL) implementation
Fault {D}etection, Identification and Reconfiguration Techniques: FDI and reconfiguration methods and the problem of their integration towards full RFTFC
No full textA research initiative within the framework of the Group for Aeronautical Research and
Technology in Europe (GARTEUR) co-operation program examined the application of
multiple fault-tolerant flight control (FTFC) algorithms in a realistic aircraft accident
scenario. An aircraft model, reconstructed using the Digital Flight Data Recorder (DFDR) of
the 1992 Amsterdam Bijlmermeer aircraft accident (Flight 1862), was used to evaluate the
algorithms in an offline benchmark and an online piloted evaluation. This paper focuses on
the experiment development for a piloted simulator evaluation of innovative reconfigurable
control algorithms applied to a damaged civil transport aircraft. The evaluation scenario,
measurements and experimental design, as well as the real-time implementation are
described. The evaluation showed that the FTFC algorithms were able to restore
conventional control strategies after the aircraft configuration has changed dramatically due
to severe failures. The algorithms supported the pilot after a failure by lowering workload
and allowing a safe return to the airport. For some failures, the handling qualities were
shown to degrade less with a failure than the baseline classical control system
Fault Diagnosis and Recovery for Aeronautic and Aerospace Missions
No full textA research initiative within the framework of the Group for Aeronautical Research and
Technology in Europe (GARTEUR) co-operation program examined the application of
multiple fault-tolerant flight control (FTFC) algorithms in a realistic aircraft accident
scenario. An aircraft model, reconstructed using the Digital Flight Data Recorder (DFDR) of
the 1992 Amsterdam Bijlmermeer aircraft accident (Flight 1862), was used to evaluate the
algorithms in an offline benchmark and an online piloted evaluation. This paper focuses on
the experiment development for a piloted simulator evaluation of innovative reconfigurable
control algorithms applied to a damaged civil transport aircraft. The evaluation scenario,
measurements and experimental design, as well as the real-time implementation are
described. The evaluation showed that the FTFC algorithms were able to restore
conventional control strategies after the aircraft configuration has changed dramatically due
to severe failures. The algorithms supported the pilot after a failure by lowering workload
and allowing a safe return to the airport. For some failures, the handling qualities were
shown to degrade less with a failure than the baseline classical control system
An automatic winding machine making superconducting coils foe the LHC correction magnets
No full textAn automatic winding machine has been designed and some experimental tests have been performed in view of the production of 21600 superconducting coils for the LHC correction magnets. The main purpose of this development is to understand the problems related to the automatic winding process and find out the best solution for the required needs. The requirements in terms of rapid prototyping and system reconfiguration needs have been demanded innovative solution for the electrical and control motion part. This paper describes the machanical configuration of the machine and the motion control system as wel
Measurement of the mass difference m(B-0)-m(B+)
No full textUsing 230 x 10(6) B (B) over bar events recorded with the BABAR detector at the e(+)e(-) storage rings PEP-II, we reconstruct approximately 4100 B-0 -> J/psi K+pi(-) and 9930 B+ -> J/psi K+ decays with J/psi -> mu(+)mu(-) and e(+)e(-). From the measured B-momentum distributions in the e(+)e(-) rest frame, we determine the mass difference m(B-0) - m(B+) = (+0.33 +/- 0.05 +/- 0.03) MeV/c(2)
Infections with HIV-1 and mycobacterium tuberculosis : the role of HLA class II alleles and HIV phenotypes
No full textHuman Immunodeficiency Virus (HIV) and Mycobacterium tuberculosis (M.tb), are the two infectious diseases causing the greatest number of deaths globally. The burden of these infections is most felt in the developing world particularly in sub-Saharan Africa. This is also a region where some of the studies in this thesis were conducted. The thesis explores both, i) host genetic factors, i.e. human leukocyte antigen (HLA) class II molecules and ii) pathogen factors in the form of HIV phenotypes in order to better understand the host-pathogen interaction in infection.We investigated in paper I the frequency of HLA class II allele frequencies in Botswana and the association of the HLA class II alleles with susceptibility or control of HIV-1 infection. Certain HLA alleles were identified to be associated with protection from HIV infection whilst other alleles were found to be associated with better control of infection.In paper II, we described a novel peptide array and used recombinant HLA class II monomers to identify peptides binding to different HLA class II monomers alleles. HIV-1 peptides binding to three common HLA class II alleles (HLA DRB1*0101, DRB1*1501 and DRB1*0401) were identified. Some of the HLA class II binding peptides were further explored using intracellular cytokine staining (ICS) to determine if they serve as T-cell epitopes and are able to elicit a CD4+ T-cell response.We proceeded to implement the assay described in paper II to identify peptides from sixty-one M.tb proteins for binding to the three HLA class II alleles (HLA DR1, DR2 and DR4). The 61 M.tb proteins were then ranked by epitope density which helped to identify M.tb proteins that could serve as immunogens for CD4+ T-cells and ultimately as targets for M.tb vaccine design or the development of diagnostic assays.In paper IV, we investigated antibody responses directed against 7466 M.tb peptides derived from 61 M.tb proteins. The peptides were printed on a peptide microarray chip. Antibody responses from a group of patients with clinical tuberculosis were compared with the humoral recognition pattern in a well-defined healthy control cohort. This allowed the identification of peptides differentially recognized in the two groups. M.tb peptides which were exclusively recognized in serum from TB patients could be further explored for the use in diagnostic assays.We investigated in Papers V and VI HIV-1 subtype C coreceptor use in HIV patients in Botswana. Whilst paper V focused on coreceptor use in treatment naïve patients, paper VI focused on coreceptor use in patients failing antiretroviral treatment. Compared to other HIV subtypes, subtype C seems to have less variants that are purely CXCR4 using although a few dual tropic (R5X4) strains have been identified. We found using single genome sequencing that population sequencing can underestimate the prevalence of dual tropic or non R5 strains. Even in HIV subtype C infections, it would be important to first evaluate the viral phenotype before treatment with HIV coreceptor inhibitors.In conclusion, this work may advance our knowledge of host and pathogen factors that are helpful in improving or developing better interventions against HIV and M.tb.List of scientific papersI. Ndungu T, Gaseitsiwe S, Sepako E, Doualla-Bell F, Peter T, Kim S, Thior I, Novitsky VA, Essex M (2005). Major histocompatibility complex class II (HLA-DRB and -DQB) allele frequencies in Botswana: association with human immunodeficiency virus type 1 infection. Clin Diagn Lab Immunol. 12(9):1020-8. https://doi.org/10.1128/CDLI.12.9.1020-1028.2005 II. Gaseitsiwe S, Valentini D, Ahmed R, Mahdavifar S, Magalhaes I, Zerweck J, Schutkowski M, Gautherot E, Montero F, Ehrnst A, Reilly M, Maeurer M (2009). Major histocompatibility complex class II molecule-human immunodeficiency virus peptide analysis using a microarray chip. Clin Vaccine Immunol. 16(4):567-73. https://doi.org/10.1128/CVI.00441-08 III. Gaseitsiwe S, Valentine D, Mahdavifar S, Reilly M, Ehrnst A, Maeurer M (2009). Peptide microarray-based identification of Mycobacterium tuberculosis epitope binding to HLA-DRB1*0101, DRB1*1501 and DRB1*0401. Clin Vaccine Immune. [Accepted] https://doi.org/10.1128/CVI.00208-09 IV. Gaseitsiwe S, Valentini D, Mahdavifar S, Magalhaes I, Hoft DF, Zerweck J, Schutkowski M, Andersson J, Reilly M, Maeurer MJ (2008). Pattern recognition in pulmonary tuberculosis defined by high content peptide microarray chip analysis representing 61 proteins from M. tuberculosis. PLoS One. 3(12):e3840. https://doi.org/10.1371/journal.pone.0003840 V. Ndungu T, Sepako E, McLane MF, Chand F, Bedi K, Gaseitsiwe S, Doualla-Bell F, Peter T, Thior I, Moyo SM, Gilbert PB, Novitsky VA, Essex M (2006). HIV-1 subtype C in vitro growth and coreceptor utilization. Virology. 347(2): 247-60. https://doi.org/10.1016/j.virol.2005.11.047 VI. Gaseitsiwe S, Pramanik L, Mine M, Essex M, Ehrnst A (2009). Coreceptor use in HIV-1 subtype C strains from patients failing antiretroviral treatment in Botswana. [Manuscript]</p
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