The Experts below are selected from a list of 219 Experts worldwide ranked by ideXlab platform

Wu Rui - One of the best experts on this subject based on the ideXlab platform.

  • Characteristic Analysis of Tripole HVDC Power Transmission
    Power system technology, 2013
    Co-Authors: Wu Rui
    Abstract:

    Tripole high voltage direct current(HVDC) power transmission is a new technology suitable for capacity-increase of existing AC power transmission lines.The structure of main circuit of tripole HVDC power transmission is presented,and two connection modes of the third pole,namely anti-parallel valves and anti-parallel thyristors within same valve,which are the key parts in the implementation of tripole HVDC power transmission,are compared,and research results show that the latter is more suitable to be applied in practical engineering projects.By means of theoretical derivation,the principle of current modulation adopted in tripole HVDC power transmission system is analyzed.After turning AC transmission lines into bipolar and tripolar HVDC power transmission lines respectively,the transmission capacity,Internal Redundancy,overload capacity and economy are compared and the conclusion is the latter is better than the former.Finally,according to current national conditions in China,the technology of tripole HVDC power transmission is compared with other approaches for capacity-increase of existing AC power transmission lines,and its application prospect in China is preliminarily discussed.

Christina H. Stenström - One of the best experts on this subject based on the ideXlab platform.

  • Functional index-2: Validity and reliability of a disease-specific measure of impairment in patients with polymyositis and dermatomyositis
    Arthritis and rheumatism, 2006
    Co-Authors: Helene Alexanderson, Ingrid E. Lundberg, Lisbet Broman, Anna Tollbäck, Annika Josefson, Christina H. Stenström
    Abstract:

    Objective To revise the content of the Functional Index in myositis (FI) and to evaluate measurement properties of a revised FI. Methods Previously performed FI (n = 287) were analyzed for Internal Redundancy and consistency, and ceiling and floor effects. Content was evaluated and a preliminary revised FI was developed. To evaluate the construct validity of the preliminary revised FI, it was compared with isokinetic measurements of muscular strength and endurance, the Myositis Activities Profile, disease impact on general wellbeing, and creatine phosphokinase levels. Minor adjustments were made and the revised FI was investigated for interrater reliability and intrarater reliability over a 1-week period. After this, some minor, additional adjustments were made leading to the final version, FI-2. Results Five tasks were removed from the original FI due to ceiling effects. Performance pace and number of repetitions were modified for the remaining tasks. A moderate correlation (rs = 0.58) was found between the shoulder flexion task of the preliminary revised FI and isokinetic measurements of shoulder flexion endurance. Intraclass correlation coefficient (ICC) for interrater reliability of the revised FI varied from 0.86–0.99 with no systematic differences. ICC for intrarater reliability varied from 0.56–0.99 with systematic differences (P < 0.05) between test and retest in 3 of the tasks. The sit-up task was excluded due to low intrarater reliability resulting in the final 7-item FI-2. There was a good correlation between tasks on the right and left side suggesting that the FI-2 could be performed unilaterally. Conclusion The FI-2 is a valid and reliable outcome measure of impairment for patients with polymyositis or dermatomyositis. It is well tolerated and the unilateral FI-2 requires a maximum of 20 minutes to perform. Further evaluation of sensitivity to change and testing in healthy individuals needs to be conducted.

  • The juvenile arthritis foot disability index: development and evaluation of measurement properties.
    The Journal of rheumatology, 2004
    Co-Authors: Marie André, Stefan Hagelberg, Christina H. Stenström
    Abstract:

    OBJECTIVE: To develop a new juvenile arthritis foot disability index (JAFI) and to test it for validity and reliability. METHODS: Samples of 14 children/adolescents and 30 children/adolescents with juvenile idiopathic arthritis (JIA) and 29 healthy children/adolescents participated. We used a questionnaire derived from the International Classification of Functioning, Disability and Health that included 27 statements divided into the dimensions Impairment, Activity Limitation, and Participation Restriction. Comments on the contents were invited from parents and adolescents. Convergent and divergent construct validity was examined by comparing the 3 JAFI dimensions to joint impairment scores, the Childhood Health Assessment Questionnaire (CHAQ), and self-rated, foot-related participation restriction. Known groups construct validity was assessed by comparing answers from children with JIA to those from healthy children. Test-retest stability was investigated over one week. RESULTS: One item was added after suggestions from 2 participants. A consistent pattern of increasing JAFI scores was found with increasing joint impairment scores, CHAQ scores, and self-rated foot-related participation restriction. Foot-related disability as assessed by JAFI was more pronounced in children with JIA than in healthy controls. One statement showing a floor effect was excluded. No Internal Redundancy (rs > 0.90) between items was found, and Internal consistency within each subscale was satisfactory (rs > 0.50) for all items but one. No systematic differences were found between test and retest, and weighted kappa coefficients for the 3 JAFI dimensions were 0.90, 0.85, and 0.88. CONCLUSION: The JAFI appears to be valid and reliable for assessing foot-related disability among children/adolescents with JIA. Its sensitivity to change remains to be investigated.

  • Development of the myositis activities profile--validity and reliability of a self-administered questionnaire to assess activity limitations in patients with polymyositis/dermatomyositis.
    The Journal of rheumatology, 2002
    Co-Authors: Helene Alexanderson, Ingrid E. Lundberg, Christina H. Stenström
    Abstract:

    OBJECTIVE: To develop a disease-specific questionnaire for assessing limitations in activities of daily life, the Myositis Activities Profile (MAP), and to investigate its validity and reliability. METHODS: Groups of 10, 27, 31, and 17 patients with polymyositis (PM) or dermatomyositis (DM) participated in different parts of the study. In the first draft of the MAP, patients rated their difficulty and experienced importance of selected activities from the International Classification of Impairments, Disabilities, and Handicaps (ICIDH)-2 Beta-2 draft. The 37 highest rated activities formed a second draft of the MAP, which was analyzed for Internal Redundancy and consistency. For construct validity a third draft was correlated with CPK levels, the Functional Index in myositis (FI), the Arthritis Impact Measurement Scales-2 (AIMS2), the Health Assessment Questionnaire (HAQ), and subjective global disease impact. Test-retest reliability over one week was investigated. RESULTS: There were several expected correlations (rs > 0.50) between subscales of the MAP and corresponding subscales of the AIMS2, and a 31 item MAP correlated moderately with the HAQ (rs = 0.70) and less with the FI (rs = 0.55), subjective global disease impact (rs = 0.43), and CPK levels (rs = 0.17). No systematic differences were found between test and retest, and weighted kappa coefficients ranged from Kw = 0.56 to 0.77. CONCLUSION: The MAP seems to be a valid and reliable method for assessing activity limitations in patients with PM and DM.

  • Reliability and validity of a Swedish version of the Revised Leeds Disability Questionnaire for patients with ankylosing spondylitis.
    Scandinavian journal of rheumatology, 2000
    Co-Authors: Christina H. Stenström, Sylvia Hellström, Maria Hultgren, Marie Wikström
    Abstract:

    The aim of the study was to investigate the reliability and the validity of a Swedish version of the Revised Leeds Disability Questionnaire (RLDQ). Forty-two patients, 36 men and 6 women, median age 52.5 years, median symptom duration 24 years, with spondylarthropathy were assessed with the RLDQ, three questions on the content of the questionnaire, and range-of-motion measures. The results indicated satisfactory test-retest stability and Internal consistency, and only minor Internal Redundancy. RLDQ items were generally considered relevant and suggested additions were similar to items already included in the questionnaire. Patients with low disability scores tended to be older and have better joint mobility than those with higher scores. Physiotherapists observed and scored disability significantly higher than patients. Correlations between subscores of the RLDQ and range-of-motion measures were in the main weak. In conclusion the Swedish version of the RLDQ may be considered as reliable and valid.

Renaud Sirdey - One of the best experts on this subject based on the ideXlab platform.

  • Thwarting Fault Attacks using the Internal Redundancy Countermeasure (IRC)
    2018
    Co-Authors: Benjamin Lac, Anne Canteaut, Jacques Fournier, Renaud Sirdey
    Abstract:

    A growing number of connected objects, with their high performance and low-resources constraints, are embedding lightweight ciphers for protecting the confidentiality of the data they manipulate or store. Since those objects are easily accessible, they are prone to a whole range of physical attacks, one of which are fault attacks against for which countermeasures are usually expensive to implement, especially on off-the-shelf devices. For such devices, we propose a new generic software countermeasure, called the Internal Redundancy Countermeasure (IRC), to thwart most fault attacks while preserving the performances of the targeted cipher. We report practical experiments showing that IRC successfully thwarts fault attacks on the block cipher PRIDE and on the stream cipher TRIVIUM for which we protect both the initialization and the keystream generation.

  • Thwarting Fault Attacks against Lightweight Cryptography using SIMD Instructions
    2018
    Co-Authors: Benjamin Lac, Anne Canteaut, Jacques Jean-alain Fournier, Renaud Sirdey
    Abstract:

    A growing number of connected objects, with their high performance and low-resources constraints, are embedding lightweight ciphers for protecting the confidentiality of the data they manipulate or store. Since those objects are easily accessible, they are prone to a whole range of physical attacks, one of which are fault attacks against for which countermeasures are usually expensive to implement, especially on off-the-shelf devices. For such devices, we propose a new generic software countermeasure, called the Internal Redundancy Countermeasure (IRC), to thwart most fault attacks while preserving the performances of the targeted cipher. We report practical experiments showing that IRC successfully thwarts fault attacks on the block cipher PRIDE and on the stream cipher TRIVIUM for which we protect both the initialization and the keystream generation.

Ben Somers - One of the best experts on this subject based on the ideXlab platform.

  • A Novel Spectral Library Pruning Technique for Spectral Unmixing of Urban Land Cover
    Remote Sensing, 2017
    Co-Authors: Jeroen Degerickx, Akpona Okujeni, Marian-daniel Iordache, Martin Hermy, Sebastian Van Der Linden, Ben Somers
    Abstract:

    Spectral unmixing of urban land cover relies on representative endmember libraries. For repeated mapping of multiple cities, the use of a generic spectral library, capturing the vast spectral variability of urban areas, would constitute a more operational alternative to the tedious development of image-specific libraries prior to mapping. The size and heterogeneity of such a generic library requires an efficient pruning technique to extract site-specific spectral libraries. We propose the “Automated MUsic and spectral Separability based Endmember Selection technique” (AMUSES), which selects endmember subsets with respect to the image to be processed, while accounting for Internal Redundancy. Experiments on simulated hyperspectral data from Brussels (Belgium) showed that AMUSES selects more relevant endmembers compared to the conventional Iterative Endmember Selection (IES) approach. This ultimately improved mapping results (kappa increased from 0.71 to 0.83). Experiments on real HyMap data from Berlin (Germany) using a combination of libraries from different cities underlined the potential of AMUSES for handling libraries with increasing levels of generality (RMSE decreased from 0.18 to 0.15, while only using 55% of the number of spectra compared to IES). Our findings contribute to the value of generic spectral databases in the development of efficient urban mapping workflows.

J. Lieb - One of the best experts on this subject based on the ideXlab platform.

  • DSN - A fault tolerant signal processing computer
    Proceeding International Conference on Dependable Systems and Networks. DSN 2000, 1
    Co-Authors: Kenneth E. Prager, M. Vahey, W. Farwell, J. Whitney, J. Lieb
    Abstract:

    A fault tolerant computer has been designed for radiation environments which employs COTS components. The use of radiation-tolerant but not fully hardened COTS devices provides significantly higher performance than specialty, fully hardened parts. The computer architecture consists of multiple, redundant processing nodes, each containing levels of Internal Redundancy, and multiple point-to-point communication ports on a crossbar switch. The nodes are linked together via ports to form a distributed crossbar network with inherent fault tolerance. A key attribute of the architecture is the provision for selectable levels of error detection and recovery. The trade-offs between performance and degree of fault tolerance can be dynamically adjusted to meet specific system needs and parts selection at any particular time.