Applying Vector Fitting for Measurement-based Multiple-Input Multiple-Output Model Identification of a Grid-Forming Converter

This paper presents an approach for applying Vector Fitting (VF) to identify a small-signal state-space model of a power electronic converter represented as a multiple-input multiple-output (MIMO) system. A workflow for the proposed model identification procedure is presented, with focus on aspects related to the processing of data from measurements and on the configuration of the VF algorithm. An example of how a small-signal state-space model can be identified from laboratory measurements on a 50 kW grid-forming converter is presented to demonstrate how VF is suitable for identifying black-box MIMO models of power converters. The identification procedure is applied to the full matrix of transfer functions between the input and output combinations obtained from the laboratory measurements. The accuracy of the resulting state-space model is verified in the frequency-domain and by time-domain simulations. Finally, limitations of the presented approach are discussed. Index Terms—power electronic systems, model identification, state-space models, MIMO systems, laboratory experimentsApplying Vector Fitting for Measurement-based Multiple-Input Multiple-Output Model Identification of a Grid-Forming ConverteracceptedVersio

Polynomial Fitting of Operating Point Dependency in Small-Signal State-Space Models for Power Electronic Converters

This paper presents an approach for representing nonlinear operating point dependencies in small-signal state-space modelling of power electronic converters. The intended application is for unifying a set of small-signal models identified from black-box simulation models or physical measurements into a single operating point dependent model. The approach is based on a polynomial fitting of the operating point dependency of the matrix elements in a state-space modal representation. The fitted expressions for the matrix elements provide a single model that can be utilized for small-signal analysis in a wide range of operating conditions and prevents the need for investigation of individual models at each operation point. Two different cases are discussed for evaluating the applicability of the presented approach, including a grid-forming converter with a Virtual Synchronous Machine (VSM)-based control and a conventional grid-following converter with dc-link voltage control. The results show that a quadratic fitting of the matrix elements can provide acceptable model accuracy in most cases. Index Terms—power electronic systems, model identification, state-space models, small-signal analysis, MIMO-systems, laboratory experimentsPolynomial Fitting of Operating Point Dependency in Small-Signal State-Space Models for Power Electronic ConvertersacceptedVersio

How Emotion Strengthens the Recollective Experience: A Time-Dependent Hippocampal Process

Emotion significantly strengthens the subjective recollective experience even when objective accuracy of the memory is not improved. Here, we examine if this modulation is related to the effect of emotion on hippocampal-dependent memory consolidation. Two critical predictions follow from this hypothesis. First, since consolidation is assumed to take time, the enhancement in the recollective experience for emotional compared to neutral memories should become more apparent following a delay. Second, if the emotion advantage is critically dependent on the hippocampus, then the effects should be reduced in amnesic patients with hippocampal damage. To test these predictions we examined the recollective experience for emotional and neutral photos at two retention intervals (Experiment 1), and in amnesics and controls (Experiment 2). Emotional memories were associated with an enhancement in the recollective experience that was greatest after a delay, whereas familiarity was not influenced by emotion. In amnesics with hippocampal damage the emotion effect on recollective experience was reduced. Surprisingly, however, these patients still showed a general memory advantage for emotional compared to neutral items, but this effect was manifest primarily as a facilitation of familiarity. The results support the consolidation hypothesis of recollective experience, but suggest that the effects of emotion on episodic memory are not exclusively hippocampally mediated. Rather, emotion may enhance recognition by facilitating familiarity when recollection is impaired due to hippocampal damage

Beliefs About Medication and Uptake of Preventive Therapy in Women at Increased Risk of Breast Cancer: Results From a Multicenter Prospective Study

Introduction Uptake of preventive therapies for breast cancer is low. We examined whether women at increased risk of breast cancer can be categorized into groups with similar medication beliefs, and whether belief group membership was prospectively associated with uptake of preventive therapy. Patients and Methods Women (n = 732) attending an appointment to discuss breast cancer risk were approached; 408 (55.7%) completed the Beliefs About Medicines and the Perceived Sensitivity to Medicines questionnaires. Uptake of tamoxifen at 3 months was reported in 258 (63.2%). The optimal number of belief groups were identified using latent profile analysis. Results Uptake of tamoxifen was 14.7% (38/258). One in 5 women (19.4%; 78/402) reported a strong need for tamoxifen. The model fit statistics supported a 2-group model. Both groups held weak beliefs about their need for tamoxifen for current and future health. Group 2 (38%; 154/406 of the sample) reported stronger concerns about tamoxifen and medicines in general, and stronger perceived sensitivity to the negative effects of medicines compared with group 1 (62%; 252/406). Women with low necessity and lower concerns (group 1) were more likely to initiate tamoxifen (18.3%; 33/180) than those with low necessity and higher concerns (group 2) (6.4%; 5/78). After adjusting for demographic and clinical factors, the odds ratio was 3.37 (95% confidence interval, 1.08-10.51; P = .036). Conclusion Uptake of breast cancer preventive therapy was low. A subgroup of women reported low need for preventive therapy and strong medication concerns. These women were less likely to initiate tamoxifen. Medication beliefs are targets for supporting informed decision-making

Tales of the unexpected: the selection of British party leaders since 1963

Jeremy Corbyn’s election as Leader of the Labour Party in 2015 stunned observers and practitioners of British politics alike. In this article, we first outline a theoretical framework that purports to explain why political parties operating in parliamentary systems choose the leaders they do. We then examine 32 leadership successions involving five major British parties since 1963, and note that many of these were unexpected, in that they were triggered by unforeseen circumstances, such as the sudden death or resignation of the incumbent. Examining each party in turn, we briefly explain why the winners won and identify at least eight cases (a quarter of our sample) where a candidate widely expected to prevail at the outset was ultimately defeated by a ‘dark horse’, ‘second favourite’ or even ‘rank outsider’. Of these, Corbyn’s election in 2015 was the most unexpected and, consistent with the findings of studies of party leadership conventions in other parliamentary systems, namely Canada and Spain, suggests that ideological and policy concerns are sometimes more important than considerations of party unity and electability, especially when a leadership contest is dominated by party activists

Impact of Chlamydia trachomatis in the reproductive setting: British Fertility Society Guidelines for practice

Chlamydia trachomatis infection of the genital tract is the most common sexually transmitted infection and has a world-wide distribution. The consequences of infection have an adverse effect on the reproductive health of women and are a common cause of infertility. Recent evidence also suggests an adverse effect on male reproduction. There is a need to standardise the approach in managing the impact of C. trachomatis infection on reproductive health. We have surveyed current UK practice towards screening and management of Chlamydia infections in the fertility setting. We found that at least 90% of clinicians surveyed offered screening. The literature on this topic was examined and revealed a paucity of solid evidence for estimating the risks of long-term reproductive sequelae following lower genital tract infection with C. trachomatis. The mechanism for the damage that occurs after Chlamydial infections is uncertain. However, instrumentation of the uterus in women with C. trachomatis infection is associated with a high risk of pelvic inflammatory disease, which can be prevented by appropriate antibiotic treatment and may prevent infected women from being at increased risk of the adverse sequelae, such as ectopic pregnancy and tubal factor infertility. Recommendations for practice have been proposed and the need for further studies is identified

Scoping potential routes to UK civil unrest via the food system: Results of a structured expert elicitation

We report the results of a structured expert elicitation to identify the most likely typesof potential food system disruption scenarios for the UK, focusing on routes to civil unrest. Wetake a backcasting approach by defining as an end-point a societal event in which 1 in 2000 peoplehave been injured in the UK, which 40% of experts rated as “Possible (20–50%)”, “More likely thannot (50–80%)” or “Very likely (>80%)” over the coming decade. Over a timeframe of 50 years, thisincreased to 80% of experts. The experts considered two food system scenarios and ranked theirplausibility of contributing to the given societal scenario. For a timescale of 10 years, the majorityidentified a food distribution problem as the most likely. Over a timescale of 50 years, the expertswere more evenly split between the two scenarios, but over half thought the most likely route tocivil unrest would be a lack of total food in the UK. However, the experts stressed that the variouscauses of food system disruption are interconnected and can create cascading risks, highlighting theimportance of a systems approach. We encourage food system stakeholders to use these results intheir risk planning and recommend future work to support prevention, preparedness, response andrecovery planning

Mitochondrial physiology

As the knowledge base and importance of mitochondrial physiology to evolution, health and disease expands, the necessity for harmonizing the terminology concerning mitochondrial respiratory states and rates has become increasingly apparent. The chemiosmotic theory establishes the mechanism of energy transformation and coupling in oxidative phosphorylation. The unifying concept of the protonmotive force provides the framework for developing a consistent theoretical foundation of mitochondrial physiology and bioenergetics. We follow the latest SI guidelines and those of the International Union of Pure and Applied Chemistry (IUPAC) on terminology in physical chemistry, extended by considerations of open systems and thermodynamics of irreversible processes. The concept-driven constructive terminology incorporates the meaning of each quantity and aligns concepts and symbols with the nomenclature of classical bioenergetics. We endeavour to provide a balanced view of mitochondrial respiratory control and a critical discussion on reporting data of mitochondrial respiration in terms of metabolic flows and fluxes. Uniform standards for evaluation of respiratory states and rates will ultimately contribute to reproducibility between laboratories and thus support the development of data repositories of mitochondrial respiratory function in species, tissues, and cells. Clarity of concept and consistency of nomenclature facilitate effective transdisciplinary communication, education, and ultimately further discovery

Mitochondrial physiology

As the knowledge base and importance of mitochondrial physiology to evolution, health and disease expands, the necessity for harmonizing the terminology concerning mitochondrial respiratory states and rates has become increasingly apparent. The chemiosmotic theory establishes the mechanism of energy transformation and coupling in oxidative phosphorylation. The unifying concept of the protonmotive force provides the framework for developing a consistent theoretical foundation of mitochondrial physiology and bioenergetics. We follow the latest SI guidelines and those of the International Union of Pure and Applied Chemistry (IUPAC) on terminology in physical chemistry, extended by considerations of open systems and thermodynamics of irreversible processes. The concept-driven constructive terminology incorporates the meaning of each quantity and aligns concepts and symbols with the nomenclature of classical bioenergetics. We endeavour to provide a balanced view of mitochondrial respiratory control and a critical discussion on reporting data of mitochondrial respiration in terms of metabolic flows and fluxes. Uniform standards for evaluation of respiratory states and rates will ultimately contribute to reproducibility between laboratories and thus support the development of data repositories of mitochondrial respiratory function in species, tissues, and cells. Clarity of concept and consistency of nomenclature facilitate effective transdisciplinary communication, education, and ultimately further discovery