Siemens (Netherlands)

The distribution of the peak-to-average power (PAP) ratio of an OFDM signal is derived, showing that large PAP ratios only occur very infrequently. Because of this, PAP reducing techniques which distort the signal can be quite effective, since only a small fraction of the OFDM signal has to be distorted. One example of such a technique is peak windowing. It is shown that peak windowing can achieve PAP ratios around 4 dB for an arbitrary number of subcarriers, at the cost of a slight increase in the BER and out-of-band radiation. Simulations with realistic power amplifier models show that a backoff of about 5 dB is required to get an out-of-band radiation level of 30 dB below the in-band spectral density.

Template protection techniques are used within biometric systems in order to safeguard the privacy of the system's subjects. This protection also includes unlinkability, i.e., preventing cross-matching between two or more reference templates from the same subject across different applications. In the literature, the template protection techniques based on fuzzy commitment, also known as the code-offset construction, have recently been investigated. Recent work presented the decodability attack vulnerability facilitating cross-matching based on the protected templates and its theoretical analysis. First, we extend the theoretical analysis and include the comparison between the system and cross-matching performance. We validate the presented analysis using real biometric data from the MCYT fingerprint database. Second, we show that applying a random bit-permutation process secures the fuzzy commitment scheme from cross-matching based on the decodability attack.

A diagnosis of 3-methylglutaconic aciduria type I (OMIM: 250950) based on elevated urinary excretion of 3-methylglutaconic acid (3MGA), 3-methylglutaric acid (3MG) and 3-hydroxyisovaleric acid (3HIVA) was made in a 61-year-old female patient presenting with leukoencephalopathy slowly progressing over more than 30 years. The diagnosis was confirmed at the enzymatic and molecular level. In vivo brain MR spectroscopic imaging (MRSI) was performed at 3.0 T, and one-dimensional and two-dimensional in vitro NMR spectroscopy of body fluids of the patient was performed at 11.7 T. Additionally, we measured 1D (1)H-NMR spectra of urine of seven patients with a total of four different inborn errors of leucine metabolism. Increased concentrations of 3HIVA, 3MGA (cis and trans) and 3MG were observed in the NMR spectra of the patient's urine. In the cerebrospinal fluid, the 3HIVA concentration was 10 times higher than in the plasma of the patient and only the cis isomer of 3MGA was observed. In vivo brain MRSI showed an abnormal resonance at 1.28 ppm that may be caused by 3HIVA. Comparison of (1)H-NMR spectra of urine samples from all eight patients studied, representing five different inborn errors of leucine metabolism, showed that each disease has typical NMR characteristics. Our leukoencephalopathy patient suffers from a late-onset form of 3-methylglutaconic aciduria type I. In the literature, only very few adult patients with this conditions have been described, and 3HIVA accumulation in white matter in the brain has not been presented before in these patients. Our data demonstrate that (1)H-NMR spectroscopy of urine can easily discriminate between the known inborn errors of leucine metabolism and provide the correct diagnosis.

Abstract Objectives High sensitivity (hs) cardiac troponin (cTn) assays are defined per the IFCC Committee on Clinical Application of Cardiac Biomarker (C-CB) by the ability to measure ≥ 50% of concentrations greater than the limit of detection (LoD) with an impression of ≤10% at sex-specific 99th percentiles. Our study determined the sex-specific 99th percentile upper reference limits for males and females utilizing heparinized plasma from AACC universal sample bank for the Siemens point of care (POC) Atellica ® VTLi hs-cTnI immunoassay. Methods Apparently healthy subjects, included overall 693, males 363, and females 330, following exclusionary surrogate biomarker use of hemoglobin A 1c , NT-proBNP, and eGFR, along with statin medication. hs-cTnI was measured in a central laboratory, on multiple POC Atellica ® VTLi immunoassay analyzers. The LoD was 1.24 ng/L and the 10%CV concentration was 6.7 ng/L. 99th percentile URLs were determined by the nonparametric (NP) method. Results Histograms of the hs-cTnI concentrations (ng/L) for males and females were used to visualize the distributions and concentrations in men and women and differed significantly (pre- and post-exclusion, both p <0.001). 99th percentile URLs were: overall 23 ng/L (90% CI 20–32 ng/L); male 27 ng/L (CI 21–37 ng/L); female 18 ng/L (CI 9–78 ng/L). The percentages of subjects having a measurable concentration ≥ the LoD were: overall 83.7%, male 87.3%, female 79.7%. Conclusions Our findings show the novel POC Atellica ® VTLi hs-cTnI assay meets the designation of a ‘high-sensitivity’ assay using heparinized plasma.

In this study, a commercially available unit commitment and economic despatch (UC–ED) tool is extended for the simulation of wind power integration in an international environment. An existing generation unit database for the Netherlands is extended to include conventional generation portfolios of neighbouring areas to the Netherlands. Furthermore, wind power in Germany is modelled such that the spatial correlation between wind speeds at different locations in the Netherlands and Germany is maintained. These additions allow the assessment of the benefits of international exchange for wind power integration and a comparison with other integration solutions. The UC–ED tool is applied for annual simulations of a power system with generation portfolios foreseen for the year 2014. Four variants for international exchange possibilities are investigated for different wind power penetrations. The opportunities of the following integration solutions are assessed: use of conventional generation in isolated systems,use of international markets, flexible combined heat and power (CHP), pumped hydro energy storage, compressed air energy storage and interconnection to a hydro-based system. The solutions are placed in an order of potential with respect to technical, economical and environmental aspects. The results show that the advantages of international exchange for wind power integration are large and provide an alternative for the development of energy storage facilities.

Infection imposes a serious burden on patients with systemic lupus erythematosus (SLE). The increased infection rate in SLE patients has been attributed in part to defects of immune defence. Recently, the lectin pathway of complement activation has also been suggested to play a role in the occurrence of infections in SLE. In previous studies, SLE patients homozygous for mannose-binding lectin (MBL) variant alleles were at an increased risk of acquiring serious infections in comparison with patients who were heterozygous or homozygous for the normal allele. This association suggests a correlation between functional MBL level and occurrence of infections in SLE patients. We therefore investigated the biological activity of MBL and its relationship with the occurrence of infections in patients with SLE. Demographic and clinical data were collected in 103 patients with SLE. Functional MBL serum levels and MBL-induced C4 deposition were measured by enzyme-linked immunosorbent assay using mannan as coat and an MBL- or C4b-specific monoclonal antibody. The complete MBL-dependent pathway activity was determined by using an assay that measures the complete MBL pathway activity in serum, starting with binding of MBL to mannan, and was detected with a specific monoclonal antibody against C5b-9. Charts were systematically reviewed to obtain information on documented infections since diagnosis of SLE. Major infections were defined as infections requiring hospital admission and intravenous administration of antibiotics. In total, 115 infections since diagnosis of lupus, including 42 major infections, were documented in the 103 SLE patients (mean age 41 +/- 13 years, mean disease duration 7 +/- 4 years). The percentage of SLE patients with severe MBL deficiency was similar to that in 100 healthy controls: 13% versus 14%, respectively. Although deposition of C4 to mannan and MBL pathway activity were reduced in 21% and 43% of 103 SLE patients, respectively, neither functional MBL serum levels nor MBL pathway activity was associated with infections or major infections in regression analyses. In conclusion, SLE patients frequently suffer from infections, but deficiency of functional MBL does not confer additional risk.

For offshore wind farms which are planned in sub-arctic regions like the Baltic Sea and Bohai Bay, support structure design has to account for load effects from dynamic ice-structure interaction. There is relatively high uncertainty related to dynamic ice loads as little to no load- and response data of offshore wind turbines exposed to drifting ice exists. In the present study the potential for the development of ice-induced vibrations for an offshore wind turbine on monopile foundation is experimentally investigated. The experiments aimed to reproduce at scale the interaction of an idling and operational 14 MW turbine with ice representative of 50-year return period Southern Baltic Sea conditions. A real-time hybrid test setup was used to allow the incorporation of the specific modal properties of an offshore wind turbine at the ice action point, as well as virtual wind loading. The experiments showed that all known regimes of ice-induced vibrations develop depending on the magnitude of the ice drift speed. At low speed this is intermittent crushing and at intermediate speeds is ‘frequency lock-in’ in the second global bending mode of the turbine. For high ice speeds continuous brittle crushing was found. A new finding is the development of an interaction regime with a strongly amplified non-harmonic first-mode response of the structure, combined with higher modes after moments of global ice failure. The regime develops between speeds where intermittent crushing and frequency lock-in in the second global bending mode develop. The development of this regime can be related to the specific modal properties of the wind turbine, for which the second and third global bending mode can be easily excited at the ice action point. Preliminary numerical simulations with a phenomenological ice model coupled to a full wind turbine model show that intermittent crushing and the new regime result in the largest bending moments for a large part of the support structure. Frequency lock-in and continuous brittle crushing result in significantly smaller bending moments throughout the structure.

Battery energy storage systems (BESSs) offer many desirable services from peak demand lopping/valley filling too fast power response services. These services can be scheduled so they enhance each other; in this manner, the inverter size is effectively leveraged with battery capacity. A variable cost for under‐frequency service provision will be required to incentivise this type of operation, and various options are explored in this study. It is demonstrated that BESSs may struggle for profitability under certain service payments; however, returns can be maximised through revenue stacking. In this study, enhanced service provision results in increased power system service provision and returns from energy arbitrage. A 10 and 2 years datasets, containing information on the Irish power system, are used to investigate potential per MW revenue from a BESS with a 1.5 and 2.5 h batteries. Three statistically derived, engineering‐based, power system service scalar multipliers are investigated and compared with the scalar being introduced on the Irish system. It is demonstrated that flexible service payments can be increased by more than 10% while receiving arbitrage payments. The seasonal variation in BESS revenue is investigated and observed to be mitigated or exacerbated by service scalars.

BACKGROUND: High-sensitivity cardiac troponin (hs-cTn) assays enable more precise use of traditional diagnostic strategies and earlier rule-out/rule-in at 0/1 h or 0/2 h after presentation of acute myocardial infarction (AMI). Availability of hs-cTn measurements at point-of-care (POC) can improve timely management of AMI patients. A roadmap for regulatory and analytical validation is exemplified with studies with the Atellica VTLi hs-cTnI at POC. METHODS: High-sensitivity performance was assessed with AACC/IFCC expert recommendations. Clinical Laboratory Standards Institute protocols were used for characterizing limit of blank, limit of detection (LoD), limit of quantitation (LoQ), 10% CV, precision, linearity, and analytic specificity with several reagent lots. Bland-Altman, Passing-Bablok, and hematocrit bias plots compared hs-cTnI measurement in lithium-heparin plasma (PL) and whole blood (WB) matrices. RESULTS: LoB was 0.55 ng/L; LoD and LoQ were 1.24 ng/L and 2.1 ng/Lm for PL and 1.60 ng/L and 3.7 ng/L for WB, respectively. The male 99th percentile is 27 ng/L, and female 99th percentile upper reference limit is 18 ng/L; 10% CVs were 6.7 ng/L for PL and 8.9 ng/L for WB. Also ≥50% of hs-cTnI values for healthy cohorts exceeded the LoD, confirming high-sensitivity performance. Linearity spanned from LoQ to 1250 ng/L. Specificity was >90% for 40 potential interferences; no hook effect was detected. WB and PL correlation was WB = 1.02*plasma + 0.3 ng/L (r = 0.996, n = 152). No hs-cTnI association with hematocrit was detected (R2 = 0.003). CONCLUSION: This analytical roadmap showed high-sensitivity performance, good analytic characteristics, and excellent PL and WB agreement for the Atellica VTLi hs-cTnI POC system. Essential clinical performance studies in patients by intended POC users may now commence.

OBJECTIVES: To examine: (1) the relationships between aerobic capacity, work ability and sick leave; (2) the potential mediating effect of work ability in the relationship between aerobic capacity and sick leave; and (3) the influence of age on these relationships. METHODS: Information on aerobic capacity (predicted VO(2max)), age, gender, type of work, cardiovascular risk and body mass index was collected from 580 workers at baseline. Work ability was assessed with the Work Ability Index at first follow-up (mean 3.4±1.3 years after baseline). The second follow-up period was defined as the time between completing the Work Ability Index and the first registered sick leave episode. Mediation analyses were performed using linear and Cox regression models. RESULTS: A lower aerobic capacity was found to be significantly related to sick leave (HR=0.98; τ=-0.018; 95% CI 0.970 to 0.994). There was a significant positive relationship between aerobic capacity and work ability (α=0.165; 95% CI 0.122 to 0.208). Also, lower work ability was significantly related to sick leave after controlling for aerobic capacity (HR=0.97; β=-0.033; 95% CI 0.949 to 0.987). The mediating effect of work ability in the relationship between aerobic capacity and sick leave was -0.005 (SE=0.002), and mediated 27.8% (95% CI 10.4 to 45.2) of the total effect of aerobic capacity on sick leave. Age did not influence the relationship between aerobic capacity and sick leave. CONCLUSIONS: Fit workers had better work ability, and both fit workers and workers with higher work ability were at lower risk of starting an episode of sick leave.

Considerable variations in environmental site conditions can exist within large offshore wind farms leading to divergent fatigue loads on support structures. An efficient frequency-domain method to calculate wave-induced fatigue loads on offshore wind turbine monopile foundations was developed. A verification study with time-domain simulations for a 4MW offshore wind turbine showed result accuracies of more than 90% for equivalent bending moments at mudline and interface level. This accuracy and computation times in the order of seconds make the frequency-domain method ideal for preliminary design and support structure optimization. The model is applied in sensitivity analysis of fatigue loads using Monte-Carlo simulations. Local and global sensitivity studies and a probabilistic assessment give insight into the importance of site parameters like water depth, soil stiffness, wave height, and wave period on fatigue loads. Results show a significant influence of water depth and wave period. This provides a basis for design optimization, load interpolation and uncertainty analysis in large wind farms.

Lower levels of automation are designed to work in specific conditions referred to as the Operational Design Domain (ODD). Beyond these conditions, the human driver is expected to take control. A mismatch between a driver's understanding and expectations of the automated vehicle capabilities and its actual capabilities as prescribed in the Original Equipment Manufacturers (OEMs) manual, could affect their safety and trust in automation. The main aim of this study is to develop a method for assessing the ODD of lane keeping system equipped vehicles. The analysis method is composed of an objective driving risk measure based on the Probabilistic Driving Risk Field (PDRF), and a subjective risk measure based on driver behavior, trust and situation awareness. We demonstrate the method applicability using the Automated Lane Keeping system of the Tesla Model S. A field test was conducted with 19 participants on public roads in the Netherlands including situations within and outside the defined ODD by the OEM. Across all test situations, a mismatch was observed between the ODD specified by the OEM and by the driver. Situations outside the ODD (i.e. no-lane markings and on/off-ramp) were often regarded as within the ODD by the participants. Situations inside the ODD (i.e. tunnel and curve) were mostly correctly classified by the participants. This analysis method has the potential to aid OEMs and road operators in defining more clearly the ODD while taking into account the driver's safety and awareness of the system capabilities.

Aerial roots of hemiepiphytes are used throughout the Amazon Basin for house construction, basketry, traps and furniture. Here we describe how 15 species of hemiepiphytes are extracted by six indigenous groups in the Colombian Amazon for traditional artefacts, commercial crafts and as raw material for the furniture industry. Indigenous classification systems, use preferences, and the influence of the craft trade on indigenous livelihoods are discussed. The craft trade seems to improve the living conditions of local communities by making them less dependent from local guerrilla and coca production. However, we seriously question the sustainability of current fibre extraction. Designing adequate management plans for commercial hemiepiphytes is essential to guarantee the future supply of these valuable non-timber forest products.

ABSTRACT Traditionally, wind turbine dynamics are analyzed using computationally efficient but geometrically coarse aeroelastic models. With ever larger offshore turbines being installed in deeper waters, the wind industry is gradually moving toward more complex foundation types such as jackets and tripods. Even the simplest models of such structures have many more degrees of freedom (DoFs) than the complete wind turbine model, leading to excessive computation times. To cope with this, we can employ reduced ‘superelement’ modeling of the support structure. However, since these structures are subjected to hydrodynamic loading at a large portion of their DoFs, traditional reduction methods fail to properly describe the response to this excitation. In this paper, we therefore propose to combine superelement modeling with the concept of modal truncation augmentation, which consists in extending the reduction basis by adding ‘residual vectors’. Furthermore, we use principal component analysis to find the predominant hydrodynamic loading on the support structure. A case study is performed on a reference wind turbine model on a jacket structure, revealing both the need for coupled dynamic analysis and the shortcomings of traditional superelement models for offshore support structures. Most importantly, this case study shows that the proposed augmented superelement approach allows to create very compact yet accurate models of the complex support structure, thereby enabling efficient integrated simulation of offshore wind turbines.Copyright © 2013 John Wiley & Sons, Ltd.

Abstract Structural design of offshore wind turbine support structures is a complex process, which has many challenges. In particular in the early phase of a project it is difficult to select the appropriate structural concept and to determine structural masses with reasonable accuracy, without having to go through a time‐consuming iterative process. In the more advanced stages, care must be taken that required data for an optimized design has been collected earlier and that the right software tools are available such that all parties involved can execute the design work. In this paper, practical advice is given how this process can be organized and which methods can be used. Furthermore, common mistakes are highlighted, such that those can be avoided. Entwurfsprozess für Tragstrukturen von Offshore‐Windenergieanlagen – Praktische Vorgehensweisen und Fallstricke während unterschiedlicher Phasen. Der Entwurf von Tragstrukturen für Offshore‐Windenergieanlagen ist eine anspruchsvolle Aufgabe. Insbesondere in der frühen Entwurfsphase ist es oft schwierig, die richtige Entscheidung für das Konzept der Tragstruktur zu treffen und die strukturellen Massen mit angemessener Genauigkeit zu bestimmen, da dies häufig in einem zeitaufwendigen Iterationsprozess mündet. Im weiteren Verlauf muss sichergestellt sein, dass alle notwendigen Eingangsdaten für ein optimiertes Design vorliegen und die beteiligten Parteien über die notwendige Software verfügen. In dieser Veröffentlichung werden praktische Hinweise gegeben, wie dieser Prozess durchgeführt werden kann und welche Methoden in welcher Phase angemessen sind. Außerdem werden häufige Fehler beschrieben, damit diese vermieden werden können.

With the offshore wind industry rapidly expanding worldwide, geotechnical research is being devoted to foundation optimisation – most intensively for large-diameter monopiles. The analysis and design of monopiles still suffers from significant uncertainties in relation to cyclic/dynamic loading conditions. The aim of this work is to shed new light on dynamic soil–monopile interaction, based on the results of unique full-scale experiments performed at the Westermeerwind wind park (Netherlands). The response of a 24 m long, 5 m diameter monopile to harmonic lateral loading of varying amplitude and frequency is inspected. The analysis of original field measurements (soil accelerations and pore pressures) enables the lateral stiffness observed at the monopile head to be linked to dynamic effects occurring in the surrounding soil. The interpretation of measured data is supported by three-dimensional finite-element studies, also looking at the influence of drainage conditions and monopile size. The set of results presented supports the need for dynamics-based monopile design, as higher frequencies gain relevance in the most recent offshore wind developments.

Abstract. To increase the contribution of offshore wind energy to the global energy mix in an economically sustainable manner, it is required to reduce the costs associated with the production and operation of offshore wind turbines (OWTs). One of the largest uncertainties and sources of conservatism in design and lifetime prediction for OWTs is the determination of the global damping level of the OWT. Estimation of OWT damping based on field measurement data has hence been subject to considerable research attention and is based on the use of (preferably operational) vibration data obtained from sensors mounted on the structure. As such, it is an output-only problem and can be addressed using state-of-the-art operational modal analysis (OMA) techniques, reviewed in this paper. The evolution of classical time- and frequency-domain OMA techniques has been reviewed; however, the literature shows that the OWT vibration data are often contaminated by rotor speed harmonics of significantly high energy located close to structural modes, which impede classical damping identification. Recent advances in OMA algorithms for known or unknown harmonic frequencies can be used to improve identification in such cases. Further, the transmissibility family of OMA algorithms is purported to be insensitive to harmonics. Based on this review, a classification of OMA algorithms is made according to a set of novel suitability criteria, such that the OMA technique appropriate to the specific OWT vibration measurement setup may be selected. Finally, based on this literature review, it has been identified that the most attractive future path for OWT damping estimation lies in the combination of uncertain non-stationary harmonic frequency measurements with statistical harmonic isolation to enhance classical OMA techniques, orthogonal removal of harmonics from measured vibration signals, and in the robustification of transmissibility-based techniques.

Abstract. In the current offshore wind turbine support structure design method, the tower and foundation, which form the support structure are designed separately by the turbine and foundation designer. This method yields a suboptimal design and it results in a heavy, overdesigned and expensive support structure. This paper presents an integrated multidisciplinary approach to design the tower and foundation simultaneously. Aerodynamics, hydrodynamics, structure and soil mechanics are the modeled disciplines to capture the full dynamic behavior of the foundation and tower under different environmental conditions. The objective function to be minimized is the mass of the support structure. The model includes various design constraints: local and global buckling, modal frequencies, and fatigue damage along different stations of the structure. To show the usefulness of the method, an existing SWT-3.6-107 offshore wind turbine where its tower and foundation are designed separately is used as a case study. The result of the integrated multidisciplinary design optimization shows 12.1 % reduction in the mass of the support structure, while satisfying all the design constraints. 1.

Automated vehicles promise numerous advantages to their users. The proposed benefits could however be overshadowed by a rise in the susceptibility of passengers to motion sickness due to their engagement in non-driving tasks. Increasing attention is paid to designing vehicle motion to mitigate motion sickness. In this work, the deep reinforcement learning (DRL) method is used to plan vehicle trajectories, with a focus on minimizing low-frequency accelerations. These are known to be the primary cause of motion sickness. The goal is achieved by incorporating a frequency-weighted discomfort term into the reward function during training. The ability of the trained agent to target undesirable frequencies in accelerations is verified by comparing it with another agent trained for improving overall acceleration comfort. A reduction of 9.6% in frequency-weighted discomfort is achieved. The motion plan from the DRL agent is further compared with trajectories generated by human drivers in real-world scenarios. The results demonstrate comparable performance between the DRL agent and human drivers. Meanwhile, a significant reduction in online computation time has been observed when compared to a motion planner based on numerical optimization.

We estimate that as much as 5% of all recorded ECGs worldwide may, to some degree, suffer from poor signal quality or incorrect electrode positioning, which often interferes with correct interpretation of the ECG. Proper training of ECG technicians and regular inspection of signal quality is necessary to achieve a high standard. Due to the large amounts of ECGs recorded daily, we devised an automatic ECG quality inspection method based on the conversion of an ECG into a VCG and back again into a reconstructed ECG. Incorrectly placed electrodes as well as different types of noise can be detected with a high level of accuracy. We used this method to assess the quality of the ECGs in the learning set of the Physionet/Computing in Cardiology Challenge 2011, giving a correct interpretation of the quality of the ECGs of 92.2% which corresponded to a sensitivity of 97.0 and a specificity of 75.1%