Comparison of Operation and Maintenance of Floating 14 MW Turbines and Twin 10 MW Turbines

Turbine ratings in the past decade have grown unexpectedly fast. In 2021, Siemens Gamesa and GE revealed their new 14 MW turbine models, and it is predicted that this is not yet the rating limit that turbines can reach. Increased turbine ratings can also be achieved by putting two turbines on a single foundation. This study analyzes how operation and maintenance (O&M) would differ if a floating wind farm had twin 10 MW turbines installed on each substructure, instead of a single 14 MW turbine. This study demonstrates how the strategic O&M simulation tool compass can be used to perform this comparison. Assumptions regarding the O&M of twin turbines were estimated with the major floating twin turbine developer Hexicon AB. This study analyzed four cases—a case with 35 twin 10 MW turbines, and three cases with 50 single 14 MW turbines—to understand the potential effect of increased consumable costs, spare part lead times, and maintenance durations. All cases had the same wind farm capacity of 700 MW. The results show that O&M for cases with single turbines is at least 4.5% more expensive than the case with twin turbines. The case with twin turbines also resulted in a higher availability than any other case. Additionally, results showed that operational expenditure (OPEX) for the cases with single turbines is at least 6.0% higher in scenarios with single turbines than in the twin turbine scenario. The biggest cost contributors to the difference between scenarios were craft costs, particularly cable laying vessels and tugs. Due to the higher number of cables required for the scenario with single turbines, there is more frequent mobilization of cable vessels for cable repairs

The perceived challenge of everyday technologies in Sweden, the United States and England: Exploring differential item functioning in the everyday technology use questionnaire

Background: The changing technological environment is reflected in regular updates made to the everyday technology (ET) use questionnaire (ETUQ). Newly added ETs may not present comparable challenges across countries and diagnoses. Aims: To identify whether country context, or dementia diagnosis, impact ETs’ challenge level. Material and methods: 315 older adults from three countries were included; Sweden (n = 73), United States (n = 114), England (n = 128), and had a confirmed diagnosis of mild dementia (n = 99) or no known cognitive impairment (n = 216). Differential Items Functioning (DIF) analysis was performed on 88 ETs included in the ETUQ by country and diagnosis. The impact of DIF was evaluated in a Differential Test Functioning (DTF) analysis. Results: Nine items (10.2%) in the ETUQ showed statistically significant DIF between countries; five of which were public space ETs and none of which were information and communication technologies (ICTs). Three ICT items, and no others, showed significant DIF by diagnosis. The items’ DIF was shown to have no impact upon person measures of ability to use ET in the DTF. Conclusions and significance: The utility of the ETUQ in occupational therapy practice and research internationally is highlighted through the stability of the challenge hierarchy and lack of impact on person measures

Hubble Space Telescope Grism Spectroscopy of Extreme Starbursts Across Cosmic Time: The Role of Dwarf Galaxies in the Star Formation History of the Universe

Near infrared slitless spectroscopy with the Wide Field Camera 3, onboard the Hubble Space Telescope, offers a unique opportunity to study low-mass galaxy populations at high-redshift ($z\sim$1-2). While most high$-z$ surveys are biased towards massive galaxies, we are able to select sources via their emission lines that have very-faint continua. We investigate the star formation rate (SFR)-stellar mass ($M_{\star}$) relation for about 1000 emission-line galaxies identified over a wide redshift range of $0.3 \lesssim z \lesssim 2.3$. We use the H$_{\alpha}$ emission as an accurate SFR indicator and correct the broadband photometry for the strong nebular contribution to derive accurate stellar masses down to $M_{\star} \sim 10^{7} M_{\odot}$. We focus here on a subsample of galaxies that show extremely strong emission lines (EELGs) with rest-frame equivalent widths ranging from 200 to 1500 \AA. This population consists of outliers to the normal SFR-$M_{\star}$ sequence with much higher specific SFRs ($> 10$ Gyr$^{-1}$). While on-sequence galaxies follow a continuous star formation process, EELGs are thought to be caught during an extreme burst of star formation that can double their stellar mass in less than $100$ Myr. The contribution of starbursts to the total star formation density appears to be larger than what has been reported for more massive galaxies in previous studies. In the complete mass range $8.2 <$ log($M_{\star}/M_{\odot}$) $< 10$ and a SFR lower completeness limit of about 2 $M_{\odot}$ yr$^{-1}$ (10 $M_{\odot}$ yr$^{-1}$) at $z\sim1$ ($z \sim 2$), we find that starbursts having EW$_{rest}$(H$_{\alpha}$)$>$ 300, 200, and 100 A contribute up to $\sim13$, 18, and 34 %, respectively, to the total SFR of emission-line selected sample at $z\sim1-2$. The comparison with samples of massive galaxies shows an increase in the contribution of starbursts towards lower masses.Comment: 11 pages, 6 figures. The Astrophysical Journal, in pres

Observation of odd-parity superconductivity in UTe2

Symmetry properties of the order parameter are among the most fundamental characteristics of a superconductor. The pairing symmetry of recently discovered heavy fermion superconductor UTe2 featuring an exceedingly large upper critical field has attracted a great deal of attention. Even though it is widely believed that UTe2 possesses an odd-parity, spin-triplet pairing symmetry, direct evidence for it is lacking, especially at zero or low magnetic fields. We report here the selection-rule results of Josephson coupling between In, an s-wave superconductor, and UTe2. The orientation dependence of the Josephson coupling suggests very strongly that UTe2 possess an odd-parity pairing state of B_1u in zero magnetic fields. We also report the formation of Andreev surface bound states on the (1-10) surface of UTe2.Comment: 16 pages, 4 figures, 2 table

LGBTQ+ people, asset-based welfare and housing in the UK

The role of housing in providing a welfare asset in later life has been widely explored. With the growth in home-ownership, house price inflation, and erosion of the welfare state, housing wealth has increasingly become part of the welfare mix in advanced economies. In this paper we present analysis of housing outcomes in terms of tenure and asset value, among people who identify as lesbian, gay or bisexual in Great Britain. This shows that LGB people have poorer housing outcomes than their heterosexual counterparts: they are less likely to be homeowners; more likely to be private renters; and more likely to be social renters. We conclude by arguing that as openly LGBTQ+ people are on average younger than the rest of the population, and with intergenerational inequalities in access to home ownership are growing, this could lead to LGB people, as a group, being particularly excluded from asset-based welfare in future.Output Status: Forthcoming/Available Onlin