Entwurf von Haarnadelwicklungen unter Berücksichtigung der transienten Potenzialverteilung

With the increasing use of novel semiconductor technologies such as SiC and GaN in inverter-fed electrical machines, the switching losses of the power electronics can be reduced. However, this leads to steeper voltage gradients, resulting in a strongly nonlinear transient potential distribution along the winding of the electrical machine. As a result, the insulation system – especially the turn-to-turn insulation – is subjected to additional voltage stress. To carry out targeted dimensioning of the insulation system, it is necessary to calculate the transient potential distribution in advance. In the design of a hairpin winding, it is possible to influence the transient potential differences by employing a method called “shifting” within the winding scheme and thus to reduce the maximum potential differences that occur. On this basis, a targeted design of winding plans with hairpins can be achieved. Here, both the transient potential differences between the conductors within a slot of the stator core and the potential differences between the conductors of different phases in the end winding region of the machine are considered. Furthermore, the voltage differences between the conductors and the stator core are determined and compared for different variants. In this way, it is possible to reduce the amount of material used in the insulation system. Finally, an advantageous winding layout plan based on reduced potential differences is compared with a reference plan.Mit dem zunehmenden Einsatz von neuen Halbleitertechnologien wie SiC und GaN bei umrichtergespeisten elektrischen Maschinen können die Schaltverluste der Leistungselektronik reduziert werden. Dies führt jedoch zu größeren Spannungsgradienten, woraus sich eine stark nichtlineare transiente Potenzialverteilung entlang der Wicklung der elektrischen Maschine ergibt. Resultierend wird das Isoliersystem – insbesondere die Windungsisolierung – einer zusätzlichen Beanspruchung ausgesetzt. Um eine gezielte Dimensionierung des Isoliersystems vornehmen zu können, ist es demnach erforderlich, die transiente Potenzialverteilung vorauszuberechnen. Im Entwurfsprozess einer Haarnadelwicklung ist es möglich, durch so genanntes „Shifting“ innerhalb des Wicklungsplans die transienten Potenzialdifferenzen zu beeinflussen und somit die maximal auftretenden Potenzialdifferenzen zu reduzieren. Auf dieser Basis kann ein gezieltes Design von Wicklungsplänen mit Hairpins erfolgen. Hierbei werden sowohl die transienten Potenzialdifferenzen zwischen den Leitern innerhalb einer Nut als auch zwischen den Leitern verschiedener Stränge im Endbereich der Maschine berücksichtigt. Außerdem wird das Potenzial zwischen den Leitern und dem Blechpaket identifiziert und für verschiedene Varianten verglichen. Auf diese Weise ist es möglich, den Materialeinsatz für das Isoliersystem zu reduzieren. In einem abschließenden Vergleich wird ein vorteilhafter Nutbelegungsplan auf Basis reduzierter Potenzialdifferenzen einem Referenzplan gegenübergestellt

Einfluss der Rotorgeometrie auf Schwingungs- und Geräuschemissionen elektrischer Fahrzeugantriebe

In the field of traction machines, permanent-magnet synchronous machines are usually designed with step-skewed rotors, i. e., the rotor is skewed along the core length segment by segment by one slot pitch in order to reduce parasitic effects, such as torque ripple, and to improve the acoustic behavior. However, step-skewing the rotor segments in the axial direction reduces the fundamental flux linkage of the permanent magnets compared to an unskewed machine. Therefore, more magnet material must be used in a skewed machine than in an unskewed machine to achieve the same torque, which increases the cost. Furthermore, skewing is a comparatively complex step in the manufacturing process, which increases the production time per machine and the cost. In this article, the influence of rotor pole width modulation on the performance of v-shaped buried magnet topologies is investigated. It evaluates whether this additional modification to the machine geometry can be used to create an unskewed motor that meets the specifications for torque ripple and maximum torque while limiting noise emissions. In order to design the rotor pole width modulation in a profitable way, a combination of magnet angles is identified by an analytical network that can reduce the critical flux density spatial harmonics of the rotor, which stimulate torque ripple and acoustic noise. Afterwards, the analytical results are validated with FEM calculations. The effect of the rotor pole width modulation on torque behavior as well as acoustic noise emission is compared with the step-skewed reference machine.Permanentmagneterregte Synchronmaschinen werden im Bereich der Traktionsmaschinen in der Regel mit einer Rotorstaffelung ausgeführt, d. h. der Rotor wird ähnlich wie bei der Nutschrägung entlang des Blechpakets segmentweise um insgesamt eine Nutteilung am Umfang versetzt, um Parasitäreffekte wie Drehmomentwelligkeit zu reduzieren und das akustische Verhalten zu verbessern. Allerdings wird durch die Staffelung der Rotorsegmente in axialer Richtung die Hauptwellenflussverkettung der Permanentmagnete gegenüber einer ungestaffelten Maschine verringert. Daher muss in einer gestaffelten Maschine mehr Magnetmaterial eingesetzt werden als in einer ungestaffelten Maschine, um das gleiche Drehmoment zu erreichen, was sich in den Kosten niederschlägt. Darüber hinaus ist die Staffelung ein vergleichsweise aufwendiger Schritt im Fertigungsprozess, sodass sich die Produktionszeit je Maschine erhöht und letztendlich die Kosten steigen. In diesem Artikel wird der Einfluss einer Rotorpolweitenmodulation auf das Betriebsverhalten für V-förmig vergrabene Magnettopologien untersucht. Es wird bewertet, ob mithilfe dieser zusätzlichen Modifikation der Maschinengeometrie ein Antrieb ohne Staffelung ausgeführt werden kann, der die Vorgaben des Lastenhefts in Bezug auf die Drehmomentwelligkeit sowie auf das maximale Drehmoment einhält und gleichzeitig die Geräuschemissionen begrenzt. Zur vorteilhaften Gestaltung einer Rotorpolweitenmodulation wird eine Kombination der Magnetöffnungswinkel mittels eines analytischen Netzwerks identifiziert, die die für die Anregung von Pendelmomenten und Geräuschen kritischen Feldwellen des Rotors reduzieren kann. Anschließend werden die analytischen Ergebnisse mit FEM-Berechnungen validiert. Der Einfluss der Rotorpolweitenmodulation auf das Drehmomentverhalten sowie die Geräuschanregung wird mit der gestaffelten Referenzmaschine verglichen

Trends in, and factors associated with, HIV infection amongst tuberculosis patients in the era of anti-retroviral therapy: a retrospective study in England, Wales and Northern Ireland

Background: HIV increases the progression of latent tuberculosis (TB) infection to active disease and contributed to increased TB in the UK until 2004. We describe temporal trends in HIV infection amongst patients with TB and identify factors associated with HIV infection. / Methods: We used national surveillance data of all TB cases reported in England, Wales and Northern Ireland from 2000 to 2014 and determined HIV status through record linkage to national HIV surveillance. We used logistic regression to identify associations between HIV and demographic, clinical and social factors. / Results: There were 106,829 cases of TB in adults (≥ 15 years) reported from 2000 to 2014. The number and proportion of TB patients infected with HIV decreased from 543/6782 (8.0%) in 2004 to 205/6461 (3.2%) in 2014. The proportion of patients diagnosed with HIV > 91 days prior to their TB diagnosis increased from 33.5% in 2000 to 60.2% in 2013. HIV infection was highest in people of black African ethnicity from countries with high HIV prevalence (32.3%), patients who misused drugs (8.1%) and patients with miliary or meningeal TB (17.2%). / Conclusions: There has been an overall decrease in TB-HIV co-infection and a decline in the proportion of patients diagnosed simultaneously with both infections. However, high rates of HIV remain in some sub-populations of patients with TB, particularly black Africans born in countries with high HIV prevalence and people with a history of drug misuse. Whilst the current policy of testing all patients diagnosed with TB for HIV infection is important in ensuring appropriate management of TB patients, many of these TB cases would be preventable if HIV could be diagnosed before TB develops. Improving screening for both latent TB and HIV and ensuring early treatment of HIV in these populations could help prevent these TB cases. British HIV Association guidelines on latent TB testing for people with HIV from sub-Saharan Africa remain relevant, and latent TB screening for people with HIV with a history of drug misuse, homelessness or imprisonment should also be considered

Mapping habitat indices across river networks using spatial statistical modelling of River Habitat Survey data

Freshwater ecosystems are declining faster than their terrestrial and marine counterparts because of physical pressures on habitats. European legislation requires member states to achieve ecological targets through the effective management of freshwater habitats. Maps of habitats across river networks would help diagnose environmental problems and plan for the delivery of improvement work. Existing habitat mapping methods are generally time consuming, require experts and are expensive to implement. Surveys based on sampling are cheaper but provide patchy representations of habitat distribution. In this study, we present a method for mapping habitat indices across networks using semi-quantitative data and a geostatistical technique called regression kriging. The method consists of the derivation of habitat indices using multivariate statistical techniques that are regressed on map-based covariates such as altitude, slope and geology. Regression kriging combines the Generalised Least Squares (GLS) regression technique with a spatial analysis of model residuals. Predictions from the GLS model are ‘corrected’ using weighted averages of model residuals following an analysis of spatial correlation. The method was applied to channel substrate data from the River Habitat Survey in Great Britain. A Channel Substrate Index (CSI) was derived using Correspondence Analysis and predicted using regression kriging. The model explained 74% of the main sample variability and 64% in a test sample. The model was applied to the English and Welsh river network and a map of CSI was produced. The proposed approach demonstrates how existing national monitoring data and geostatistical techniques can be used to produce continuous maps of habitat indices at the national scale

Multilocus Inherited Neoplasia Allele Syndrome (MINAS): an update.

Funder: Cancer Research UK (CRUK); doi: https://doi.org/10.13039/501100000289Multi-locus Inherited Neoplasia Allele Syndrome (MINAS) refers to individuals with germline pathogenic variants in two or more cancer susceptibility genes(CSGs). With increased use of exome/genome sequencing it would be predicted that detection of MINAS would become more frequent. Here we review recent progress in knowledge of MINAS. A systematic literature search for reports of individuals with germline pathogenic variants in 2 or more of 94 CSGs was performed. In addition, participants with multiple primary tumours who underwent genome sequencing as part of the Rare Disease arm of the UK 100,000 Genomes Project were interrogated to detect additional cases. We identified 385 MINAS cases (211 reported in the last 5 years, 6 from 100,000 genomes participants). Most (287/385) cases contained at least one pathogenic variant in either BRCA1 or BRCA2. 108/385 MINAS cases had multiple primary tumours at presentation and a subset of cases presented unusual multiple tumour phenotypes. We conclude that, as predicted, increasing numbers of individuals with MINAS are being have been reported but, except for individuals with BRCA1/BRCA2 MINAS, individual CSG combinations are generally rare. In many cases it appears that the clinical phenotype is that which would be expected from the effects of the constituent CSG variants acting independently. However, in some instances the presence of unusual tumour phenotypes and/or multiple primary tumours suggests that there may be complex interactions between the relevant MINAS CSGs. Systematic reporting of MINAS cases in a MINAS database (e.g. https://databases.lovd.nl/shared/diseases/04296 ) will facilitate more accurate prognostic predictions for specific CSG combinations

Seeking river restoration appraisal best practice: supporting wider national and international

With growing investment in river restoration, we increasingly need to justify costs by demonstrating success and wider benefits of measures. To aid practitioners, the UK River Restoration Centre (RRC) has worked with experts to develop a practical monitoring guidance (PRAGMO) that links objectives to specific monitoring to demonstrate achievable outcomes. Feedback, however, via an on‐line questionnaire highlighted the need to rationalise the guidance contents for a new growing audience, taking advantage of new developments and incorporating the evaluation of social and economic aspects of river restoration. With these potential improvements, it is hoped that practitioners will follow this guidance, improve the quality of monitoring undertaken and share evidence of success and lessons learnt. This paper outlines how this guidance has been adopted as best practice. We discuss why we need to embed this guidance into wider monitoring protocols that can feed into national and international environmental policy and targets

Back arc extension and collision : an experimental approach of the tectonics of Asia

International audienceThe deformation of the eastern Asian lithosphere during the first part of the India-Asia collision was dominated by subduction-related extension interacting with far effects of the collision. In order to investigate the role of large-scale extension in collision tectonics, we performed analogue experiments of indentation with a model of lithosphere subjected to extension. We used a three-layer rheological model of continental lithosphere resting upon an asthenosphere of low viscosity and strained along its southern boundary by a rigid indenter progressing northward. The lithosphere model was scaled to be gravitationally unstable and to spread under its ownweight, so that extension occurred in thewhole model. The eastern boundarywas free or weakly confined and always allowed eastward spreading of the model. We studied the pattern of deformation for different boundary conditions. The experimental pattern of deformation includes a thickened zone in front of the indenter, a major northeast-trending left-lateral shear zone starting from the northwest corner of the indenter, antithetic north-south right-lateral shear zones more or less developed to the east of the indenter, and a purely extensional domain in the southeastern part of the model. In this domain, graben opening is driven by gravitational spreading, whereas it is driven by gravitational spreading and indentation in the northeastern part where grabens opened along strike-slip faults. The results are compared with the Oligo- Miocene deformation pattern of Asia consecutive to the collision of India. Our experiments bring a physical basis to models which favour distributed deformation within a slowly extruded wide region extending from the Baikal Rift to the Okhotsk Sea and to southeast Asia and Indonesia. In this large domain, the opening of backarc basins (Japan Sea, Okinawa Trough, South China Sea) and continental grabens (North China grabens) have been associated with approximately north-south-trending right-lateral strike-slip faults, which accommodated the northward penetration of India into Eurasia

Antiplatelet therapy with aspirin, clopidogrel, and dipyridamole versus clopidogrel alone or aspirin and dipyridamole in patients with acute cerebral ischaemia (TARDIS): a randomised, open-label, phase 3 superiority trial

Background: Intensive antiplatelet therapy with three agents might be more effective than guideline treatment for preventing recurrent events in patients with acute cerebral ischaemia. We aimed to compare the safety and efficacy of intensive antiplatelet therapy (combined aspirin, clopidogrel, and dipyridamole) with that of guideline-based antiplatelet therapy. Methods: We did an international, prospective, randomised, open-label, blinded-endpoint trial in adult participants with ischaemic stroke or transient ischaemic attack (TIA) within 48 h of onset. Participants were assigned in a 1:1 ratio using computer randomisation to receive loading doses and then 30 days of intensive antiplatelet therapy (combined aspirin 75 mg, clopidogrel 75 mg, and dipyridamole 200 mg twice daily) or guideline-based therapy (comprising either clopidogrel alone or combined aspirin and dipyridamole). Randomisation was stratified by country and index event, and minimised with prognostic baseline factors, medication use, time to randomisation, stroke-related factors, and thrombolysis. The ordinal primary outcome was the combined incidence and severity of any recurrent stroke (ischaemic or haemorrhagic; assessed using the modified Rankin Scale) or TIA within 90 days, as assessed by central telephone follow-up with masking to treatment assignment, and analysed by intention to treat. This trial is registered with the ISRCTN registry, number ISRCTN47823388. Findings: 3096 participants (1556 in the intensive antiplatelet therapy group, 1540 in the guideline antiplatelet therapy group) were recruited from 106 hospitals in four countries between April 7, 2009, and March 18, 2016. The trial was stopped early on the recommendation of the data monitoring committee. The incidence and severity of recurrent stroke or TIA did not differ between intensive and guideline therapy (93 [6%] participants vs 105 [7%]; adjusted common odds ratio [cOR] 0·90, 95% CI 0·67–1·20, p=0·47). By contrast, intensive antiplatelet therapy was associated with more, and more severe, bleeding (adjusted cOR 2·54, 95% CI 2·05–3·16, p<0·0001). Interpretation: Among patients with recent cerebral ischaemia, intensive antiplatelet therapy did not reduce the incidence and severity of recurrent stroke or TIA, but did significantly increase the risk of major bleeding. Triple antiplatelet therapy should not be used in routine clinical practice

Best Practices for Monitoring and Assessing the Ecological Response to River Restoration

Nature-based solutions are widely advocated for freshwater ecosystem conservation and restoration. As increasing amounts of river restoration are undertaken, the need to understand the ecological response to different measures and where measures are best applied becomes more pressing. It is essential that appraisal methods follow a sound scientific approach. Here, experienced restoration appraisal experts review current best practice and academic knowledge to make recommendations and provide guidance that will enable practitioners to gather and analyse meaningful data, using scientific rigor to appraise restoration success. What should be monitored depends on the river type and the type and scale of intervention. By understanding how habitats are likely to change we can anticipate what species, life stages, and communities are likely to be affected. Monitoring should therefore be integrated and include both environmental/habitat and biota assessments. A robust scientific approach to monitoring and appraisal is resource intensive. We recommend that appraisal efforts be directed to where they will provide the greatest evidence, including ‘flagship’ restoration schemes for detailed long-term monitoring. Such an approach will provide the evidence needed to understand which restoration measures work where and ensure that they can be applied with confidence elsewhere

Defining recovery potential in river restoration: a biological data-driven approach

Scientists and practitioners working on river restoration have made progress on understanding the recovery potential of rivers from geomorphological and engineering perspectives. We now need to build on this work to gain a better understanding of the biological processes involved in river restoration. Environmental policy agendas are focusing on nature recovery, reigniting debates about the use of “natural” reference conditions as benchmarks for ecosystem restoration. We argue that the search for natural or semi-natural analogues to guide restoration planning is inappropriate due to the absence of contemporary reference conditions. With a catchment-scale case study on the invertebrate communities of the Warwickshire Avon, a fifth-order river system in England, we demonstrate an alternative to the reference condition approach. Under our model, recovery potential is quantified based on the gap between observed biodiversity at a site and the biodiversity predicted to occur in that location under alternative management scenarios. We predict that commonly applied restoration measures such as reduced nutrient inputs and the removal of channel resectioning could be detrimental to invertebrate diversity, if applied indiscriminately and without other complementary measures. Instead, our results suggest considerable potential for increases in biodiversity when restoration measures are combined in a way that maximises biodiversity within each water bod