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Improved equivalent circuit model of HTS dynamo based on integrating a feature on frequency dependency of critical current
Get PDFThe charging current and output voltage of the High temperature superconducting (HTS) dynamo flux pumps can be calculated using a simple equivalent circuit model (ECM). Thus, the charging curve prediction would be faster. Creating a model that accurately and quickly simulates HTS Dynamos' operation enables the obtaining of expected results with sufficient accuracy before experimentation and prototyping, thereby improving design, research and development efficiency. Previous studies on ECM-based simulation indicate a growing discrepancy between simulation and experimental results as the operating frequency increases. Yet, no model has addressed this problem. In this paper, a frequency-improved ECM for HTS Dynamo based on the integration of the frequency dependence of critical current into ECM has been proposed and developed in SIMULINK, which directly addresses the aforementioned research gap. The model takes into account the impacts of dynamic resistance, the E-J Power Law, and the frequency dependence of the critical current of the HTS tape on the HTS Dynamo performance. The simulated charging current and output voltage of the HTS Dynamo were investigated by varying the rotor rotation frequency and the air gap between the permanent magnets and the HTS tape. An analysis has been carried out regarding the simulation results from the frequency-improved ECM and the original ECM, compared with the corresponding experimental data under the same operating conditions. Finally, the simulation accuracy of the frequency-improved ECM is compared with that of the ECM without considering the frequency dependence of the critical current under the same operating conditions, yielding a significant improvement, with up to a 96.7% reduction in error
La ‘longa aetas’ del poeta di Sulmona: tipologie femminili ovidiane negli Epigrammi di Decimo Magno Ausonio
No full textNo abstract available
Data-driven upscaling of composite media using artificial neural networks: a study performed via asymptotic homogenization
No full textA data-driven approach is developed, as an upscaling means for composite media to overcome the need to fully resolve the complex cell problems encountered in asymptotic homogenization. Artificial neural networks (ANNs) were applied as an instantaneous (black-box) transformation means from the input space to the output space. The former comprises the volume fraction and material properties of each microscale constituent, while the latter provides the effective properties of the homogenised model. The ANN training utilizes a training dataset that provides a sufficiently dense discretization of a continuous input-output function through sampling approaches. The deterministic low-discrepancy sequences were used to provide optimal sampling of multidimensional input space. The corresponding outputs in the dataset were generated using a semi-analytical approach. Our results indicate that the ANN achieves high accuracy. Additionally, we analyze how the size and density of the training dataset impact the accuracy of the upscaling, providing insights into the computational efficiency and applicability of data-driven methods in multiscale analyses
Socioecological determinants of dog ownership in Mara region, Tanzania
Get PDFUnderstanding domestic dog population dynamics is critical for rabies control, particularly in sub-Saharan Africa where domestic dogs are the primary virus reservoir. This study investigates demographic and environmental determinants of dog ownership in Tanzania’s Mara region, a rabies-endemic area with ecologically diverse landscapes. Using a cross-sectional household survey (n = 27,400 households), we employed mixed-effects models to assess predictors of dog ownership, dog counts, and Human-to-Dog Ratios (HDRs).
Overall, 12,975 households (47%) owned dogs, with a mean of 2.2 dogs per dog-owning household. Logistic regression revealed key predictors of ownership: urban households had reduced odds of dog ownership (OR = 0.311, CI: 0.132-0.734, while ownership likelihood increased with larger household size (adults: OR = 1.151, CI: 1.134-1.169; children: OR = 1.160, CI: 1.140-1.180), and crop (OR = 1.502, 95% CI: 1.384-1.630), shrub (OR = 1.387, 95% CI: 1.269-1.515), or tree land cover (OR = 1.708, 95% CI: 1.260-2.314) compared to built areas. However, among dog-owning households, variables had minimal practical impact on dog counts with most households (85.6%) owning 1–3 dogs regardless of household size, location, or land cover. Urban districts exhibited significantly higher HDRs (18.3:1 vs. rural 7.1:1), further influenced by land cover (tree: 5.1:1 vs. built: 8.7:1).
These findings highlight a critical divergence: while contextual factors strongly predict dog ownership, they do not meaningfully influence the number of dogs owned. Consequently, effective vaccination programmes require strategies tailored to local dog density and ownership patterns
Antigenicity of key HCV E1E2 glycoprotein neutralizing sites is genotype-independent
No full textThe development of an effective prophylactic hepatitis C virus (HCV) vaccine is a priority to achieve global elimination of the virus. Accurate assessment of the neutralizing breadth of antibodies induced by vaccines and a clear understanding of the antigenic differences between viral variants included in vaccines are both critical for vaccine development. Prior studies have indicated that HCV genotypes (gts) do not dictate the sensitivity of HCV envelope glycoprotein (E1E2) variants to neutralizing antibodies. However, most of these prior studies under- sampled variants from gts 2–6. Here, we selected a genetically diverse and representative panel of gt 2–6 E1E2 variants, used them to generate HCV pseudoparticles (HCVpp), and measured neutralization of these HCVpp by neutralizing antibodies and HCV- immune plasma from persons infected with gt 1–6 viruses. We found that neutralization results obtained with this gt 2–6 panel were remarkably similar to results obtained with a previously described, antigenically diverse, gt 1- predominant reference panel of 15 HCVpp. These data confirm that, even considering genetically diverse HCV variants across gt 1–6, E1E2 antigenicity is not dictated by gt, and that the previously published panel of 15 HCVpp represents neutralization of all HCV gts with reasonable accuracy
'Inside the belly of the monster’: the politics of race in Britain, transnational anticolonialism, and the black liberation front
No full textThis article examines anti-colonialism and Third World solidarities in Britain during the 1970s and 1980s. It does so through a study of the Black Liberation Front (BLF), a Black Power group formed in London in 1971. The BLF saw themselves as part of a global Third World solidarity, and, as activists in Britain, identified their location as ‘inside the belly of the monster’. They understood racism and colonialism as global phenomena, and offered material support to anti-colonial movements across the world, especially in Africa. The prevailing historiography of Black activism in post-war Britain foregrounds domestic anti-racism. Based on a reading of the BLF’s publications, alongside subsequent memoirs by and interviews with former BLF members, this article argues for Black activism in Britain to be viewed through a more global lens. Moreover, it shows how a deeper understanding of transnational anti-colonialism reconfigures our understanding of the domestic politics of race. Historians of decolonization must attend to how twentieth-century geographies of race and migration created the conditions for solidarities that do not fit within a metropole–colony binary
An angular dispersion-free resonant metasurface for quantum photon pair generation
No full textMetasurfaces supporting high quality factor resonances have shown the ability to enhance spontaneous parametric down-conversion (SPDC) process and are therefore seen as a promising platform for entangled quantum photon pair generation. We propose a high quality (Q) factor flat-band optical metasurface for efficient quantum light generation via SPDC. The structure consisting of periodic GaAs nano-resonators on SiO2 was numerically optimised to realise a metasurface that is dispersionless along the G–Y axis near the telecommunications band (∼1550nm). Our simulations show that the metasurface hosts two quasi–boundstates-in-the-continuum (q-BIC) modes with quality factors exceeding 109; the intentional merging of the BICs results in high-Q (>105) across a finite in-plane wave-vector range. This combination of angle-independent resonance frequency with persistently high Q mitigates the off-G degradation typical of symmetry-broken q-BICs. The design increases the optical density of states and allows for efficient collection of the generated photons using a high numerical aperture. It is anticipated that the resulting devices could be used for both quantum photon pair generation and for classical nonlinear second-harmonic generation. Our results demonstrate flat-band, high-Q metasurfaces that can be fabricated as a compact route to on-chip nonlinear and quantum photonics
Analyst information processing of risk disclosures in the EEA insurance sector: a research note
No full textPurpose – This study explores whether and how analysts covering insurers within the European Economic Area (EEA) use the mandatory risk disclosures as required under the Solvency II framework after the introduction of the Solvency and Financial Condition Report (SFCR). Design/methodology/approach – This study is exploratory in nature and draws on evidence from eight semistructured interviews with nine sell-side and credit analysts. Findings – Dialogue with analysts documents their interest in Solvency II information, though they initially rely on solvency-related information provided during earnings calls due to later SFCR disclosure dates, duplication of material in the annual report and language barriers. Analysts underline the importance of the Solvency II ratio as a key indicator of insurers’ solvency and risk. However, its direct use in the assessment process is limited by its inherent nature, comparability issues and insurers’ transparency commitments, leading analysts to prioritise simplified interpretations and narrative discussions that better serve investors’ informational needs. Research limitations/implications – The exploration of analysts’ use of Solvency II information is based on a small sample of semi-structured interviews that reflect participants’ personal opinions, and it is acknowledged that generalisation of the findings might be limited. Practical implications – The study contributes to related debates among regulatory authorities over the content and usefulness of Solvency II information, with the most recent and relevant being the Solvency II 2020 review. Originality/value – The study offers a unique natural laboratory to explore analysts’ information processing of risk disclosures, contributing to the broader and insurance-specific risk reporting literature and to the literature on the usefulness of accounting and non-accounting information for analysts
On uncertainty and the limits of intelligence
No full textDespite far-reaching reform of intelligence in recent decades, the nature and essence of intelligence work have not fundamentally changed. Intelligence remains limited, and uncertainty continues to dominate international affairs. This chapter demonstrates that effective intelligence is limited by time, structure, cognition, and politics. These four factors are interlinked, mutually reinforcing, and, together, they compound the uncertainty that characterizes the types of issues that intelligence organizations are routinely expected to contend with. Not only is uncertainty an immutable fact of global politics, but levels of uncertainty are also liable to increase in relation to the importance of the issues at stake
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