| 1. |
- Ederle, Joerg, et al.
(författare)
-
Carotid artery stenting compared with endarterectomy in patients with symptomatic carotid stenosis (International Carotid Stenting Study): an interim analysis of a randomised controlled trial
- 2010
-
Ingår i: The Lancet. - 1474-547X. ; 375:9719, s. 985-997
-
Tidskriftsartikel (refereegranskat)abstract
- Background Stents are an alternative treatment to carotid endarterectomy for symptomatic carotid stenosis, but previous trials have not established equivalent safety and efficacy. We compared the safety of carotid artery stenting with that of carotid endarterectomy. Methods The International Carotid Stenting Study (ICSS) is a multicentre, international, randomised controlled trial with blinded adjudication of outcomes. Patients with recently symptomatic carotid artery stenosis were randomly assigned in a 1:1 ratio to receive carotid artery stenting or carotid endarterectomy. Randomisation was by telephone call or fax to a central computerised service and was stratified by centre with minimisation for sex, age, contralateral occlusion, and side of the randomised artery. Patients and investigators were not masked to treatment assignment. Patients were followed up by independent clinicians not directly involved in delivering the randomised treatment. The primary outcome measure of the trial is the 3-year rate of fatal or disabling stroke in any territory, which has not been analysed yet. The main outcome measure for the interim safety analysis was the 120-day rate of stroke, death, or procedural myocardial infarction. Analysis was by intention to treat (ITT). This study is registered, number ISRCTN25337470. Findings The trial enrolled 1713 patients (stenting group, n=855; endarterectomy group, n=858). Two patients in the stenting group and one in the endarterectomy group withdrew immediately after randomisation, and were not included in the ITT analysis. Between randomisation and 120 days, there were 34 (Kaplan-Meier estimate 4.0%) events of disabling stroke or death in the stenting group compared with 27 (3.2%) events in the endarterectomy group (hazard ratio [HR] 1.28, 95% CI 0.77-2.11). The incidence of stroke, death, or procedural myocardial infarction was 8.5% in the stenting group compared with 5.2% in the endarterectomy group (72 vs 44 events; HR 1.69, 1.16-2.45, p=0.006), Risks of any stroke (65 vs 35 events; HR 1.92, 1.27-2.89) and all-cause death (19 vs seven events; HR 2.76, 1.16-6.56) were higher in the stenting group than in the endarterectomy group. Three procedural myocardial infarctions were recorded in the stenting group, all of which were fatal, compared with four, all non-fatal, in the endarterectomy group. There was one event of cranial nerve palsy in the stenting group compared with 45 in the endarterectomy group. There were also fewer haematomas of any severity in the stenting group than in the endarterectomy group (31 vs 50 events; p=0.0197). Interpretation Completion of long-term follow-up is needed to establish the efficacy of carotid artery stenting compared with endarterectomy. In the meantime, carotid endarterectomy should remain the treatment of choice for patients suitable for surgery.
|
|
| 2. |
|
|
| 3. |
|
|
| 4. |
- Veltkamp, R., et al.
(författare)
-
Characteristics of Recurrent Ischemic Stroke after Embolic Stroke of Undetermined Source: Secondary Analysis of a Randomized Clinical Trial
- 2020
-
Ingår i: JAMA Neurology. - : American Medical Association (AMA). - 2168-6149. ; 77:10, s. 1233-1240
-
Tidskriftsartikel (refereegranskat)abstract
- Importance: The concept of embolic stroke of undetermined source (ESUS) unifies a subgroup of cryptogenic strokes based on neuroimaging, a defined minimum set of diagnostic tests, and exclusion of certain causes. Despite an annual stroke recurrence rate of 5%, little is known about the etiology underlying recurrent stroke after ESUS. Objective: To identify the stroke subtype of recurrent ischemic strokes after ESUS, to explore the interaction with treatment assignment in each category, and to examine the consistency of cerebral location of qualifying ESUS and recurrent ischemic stroke. Design, Setting, and Participants: The NAVIGATE-ESUS trial was a randomized clinical trial conducted from December 23, 2014, to October 5, 2017. The trial compared the efficacy and safety of rivaroxaban and aspirin in patients with recent ESUS (n = 7213). Ischemic stroke was validated in 309 of the 7213 patients by adjudicators blinded to treatment assignment and classified by local investigators into the categories ESUS or non-ESUS (ie, cardioembolic, atherosclerotic, lacunar, other determined cause, or insufficient testing). Five patients with recurrent strokes that could not be defined as ischemic or hemorrhagic in absence of neuroimaging or autopsy were excluded. Data for this secondary post hoc analysis were analyzed from March to June 2019. Interventions: Patients were randomly assigned to receive rivaroxaban, 15 mg/d, or aspirin, 100 mg/d. Main Outcomes and Measures: Association of recurrent ESUS with stroke characteristics. Results: A total of 309 patients (205 men [66%]; mean [SD] age, 68 [10] years) had ischemic stroke identified during the median follow-up of 11 (interquartile range [IQR], 12) months (annualized rate, 4.6%). Diagnostic testing was insufficient for etiological classification in 39 patients (13%). Of 270 classifiable ischemic strokes, 156 (58%) were ESUS and 114 (42%) were non-ESUS (37 [32%] cardioembolic, 26 [23%] atherosclerotic, 35 [31%] lacunar, and 16 [14%] other determined cause). Atrial fibrillation was found in 27 patients (9%) with recurrent ischemic stroke and was associated with higher morbidity (median change in modified Rankin scale score 2 [IQR, 3] vs 0 (IQR, 1]) and mortality (15% vs 1%) than other causes. Risk of recurrence did not differ significantly by subtype between treatment groups. For both the qualifying and recurrent strokes, location of infarct was more often in the left (46% and 54%, respectively) than right hemisphere (40% and 37%, respectively) or brainstem or cerebellum (14% and 9%, respectively). Conclusions and Relevance: In this secondary analysis of randomized clinical trial data, most recurrent strokes after ESUS were embolic and of undetermined source. Recurrences associated with atrial fibrillation were a minority but were more often disabling and fatal. More extensive investigation to identify the embolic source is important toward an effective antithrombotic strategy. Trial Registration: ClinicalTrials.gov Identifier: NCT02313909.. © 2020 American Medical Association. All rights reserved.
|
|
| 5. |
- Astell, A. J., et al.
(författare)
-
Developing a pragmatic evaluation of ICTs for older adults with cognitive impairment at scale: the IN LIFE experience
- 2021
-
Ingår i: Universal Access in the Information Society. - Heidelberg, Germany : Springer. - 1615-5289 .- 1615-5297.
-
Tidskriftsartikel (refereegranskat)abstract
- Implementing information and communications technology (ICT) at scale requires evaluation processes to capture the impact on users as well as the infrastructure into which it is being introduced. For older adults living with cognitive impairment, this requires evaluation that can accommodate different levels of cognitive impairment, alongside input from family and formal caregivers, plus stakeholder organisations. The European Horizon 2020 project INdependent LIving support Functions for the Elderly (IN LIFE) set out to integrate 17 technologies into a single digital platform for older people living with cognitive impairment plus their families, care providers and stakeholders. The IN LIFE evaluation took place across six national pilot sites to examine a number of variables including impact on the users, user acceptance of the individual services and the overall platform, plus the economic case for the IN LIFE platform. The results confirmed the interest and need among older adults, family caregivers, formal caregivers and stakeholders, for information and communications technology (ICT). Relative to the baseline, quality of life improved and cognition stabilised; however, there was an overall reluctance to pay for the platform. The findings provide insights into existing barriers and challenges for adoption of ICT for older people living with cognitive impairment.
|
|
| 6. |
|
|
| 7. |
|
|
| 8. |
- Astell, A. J., et al.
(författare)
-
Developing a pragmatic evaluation of ICTs for older adults with cognitive impairment at scale : the IN LIFE experience
- 2022
-
Ingår i: Universal Access in the Information Society. - Heidelberg, Germany : Springer. - 1615-5289 .- 1615-5297. ; 21:1, s. 1-19
-
Tidskriftsartikel (refereegranskat)abstract
- Implementing information and communications technology (ICT) at scale requires evaluation processes to capture the impacton users as well as the infrastructure into which it is being introduced. For older adults living with cognitive impairment, thisrequires evaluation that can accommodate diferent levels of cognitive impairment, alongside input from family and formalcaregivers, plus stakeholder organisations. The European Horizon 2020 project INdependent LIving support Functions forthe Elderly (IN LIFE) set out to integrate 17 technologies into a single digital platform for older people living with cognitive impairment plus their families, care providers and stakeholders. The IN LIFE evaluation took place across six nationalpilot sites to examine a number of variables including impact on the users, user acceptance of the individual services andthe overall platform, plus the economic case for the IN LIFE platform. The results confrmed the interest and need amongolder adults, family caregivers, formal caregivers and stakeholders, for information and communications technology (ICT).Relative to the baseline, quality of life improved and cognition stabilised; however, there was an overall reluctance to payfor the platform. The fndings provide insights into existing barriers and challenges for adoption of ICT for older peopleliving with cognitive impairment.
|
|
| 9. |
- Mikulik, R., et al.
(författare)
-
Frequency and Predictors of Major Bleeding in Patients With Embolic Strokes of Undetermined Source NAVIGATE-ESUS Trial
- 2020
-
Ingår i: Stroke. - : Ovid Technologies (Wolters Kluwer Health). - 0039-2499 .- 1524-4628. ; 51:7, s. 2139-2147
-
Tidskriftsartikel (refereegranskat)abstract
- Background and Purpose: Risks, sites, and predictors of major bleeding during antithrombotic therapies have not been well defined for patients with recent embolic stroke of undetermined source. Methods: Exploratory analysis of major bleeds defined by International Society of Thrombosis and Hemostasis criteria occurring among 7213 participants in international NAVIGATE (New Approach Rivaroxaban Inhibition of Factor Xa in a Global Trial) embolic stroke of undetermined source randomized trial comparing rivaroxaban 15 mg daily with aspirin 100 mg daily. Results: During a median follow-up of 11 months, 85 major bleeds occurred. The most frequent site was gastrointestinal (38%), followed by intracranial (29%). Assignment to rivaroxaban (hazard ratio [HR], 2.7 [95% CI, 1.7-4.3]), East Asia region (HR, 2.5 [95% CI, 1.6-3.9]), systolic blood pressure >= 160 mm Hg (HR, 2.2 [95% CI, 1.2-3.8]), and reduced estimated glomerular filtration rate (HR, 1.2 per 10 mL/min per 1.73 m(2)decrease, [95% CI, 1.0-1.3]) were independently associated with presence of major bleeds. Five (6%) were fatal. Among 15 patients with intracerebral hemorrhage, 2 (13%) were fatal. There was no evidence of an early high-risk period following initiation of rivaroxaban. The annualized rate of intracerebral hemorrhage was 6-fold higher among East Asian participants (0.67%) versus all other regions (0.11%; HR, 6.3 [95% CI, 2.2-18.0]). Distribution of bleeding sites was similar for rivaroxaban and aspirin. Conclusions: Among embolic stroke of undetermined source patients participating in an international randomized trial, independent predictors of major bleeding were assignment to rivaroxaban, East Asia region, increased systolic blood pressure, and impaired renal function. East Asia as a region was strongly associated with risk of intracerebral hemorrhage. Estimated glomerular filtration rate should be a consideration for stratifying bleeding risk. Registration: URL:. Unique identifier: NCT02313909.
|
|
| 10. |
- Ringleb, PA, et al.
(författare)
-
Guidelines for management of ischaemic stroke and transient ischaemic attack 2008
- 2008
-
Ingår i: Cerebrovascular diseases (Basel, Switzerland). - : S. Karger AG. - 1421-9786 .- 1015-9770. ; 25:5, s. 457-507
-
Tidskriftsartikel (refereegranskat)abstract
- This article represents the update of the European Stroke Initiative Recommendations for Stroke Management. These guidelines cover both ischaemic stroke and transient ischaemic attacks, which are now considered to be a single entity. The article covers referral and emergency management, Stroke Unit service, diagnostics, primary and secondary prevention, general stroke treatment, specific treatment including acute management, management of complications, and rehabilitation.
|
|
| 11. |
|
|
| 12. |
|
|
| 13. |
|
|
| 14. |
- Chamorro, Harold R., et al.
(författare)
-
Distributed Synthetic Inertia Control in Power Systems
- 2018
-
Ingår i: Proceedings of 8th International Conference on Energy and Environment. - : Institute of Electrical and Electronics Engineers (IEEE). - 9781538639436 ; , s. 74-78
-
Konferensbidrag (refereegranskat)abstract
- Due to the increasing use of renewables into the grid connected through power converters, the rotational inertia in power systems has been reducing. Consequently the frequency response requires the activation of the so-called synthetic inertia control. The synthetic inertia control aims to inject an extra power component when the system experiences a frequency disturbance event. In this paper, it is proposed that a distributed dynamic controllers for sharing the synthetic inertia control actions between the various active power converters in the grid for the improvement of the frequency response. It is assumed that a communication structure between the synthetic inertia controllers and the local power converters is involved in the system. The convergence of the control system is reached through a game population theory and the primary frequency control has been improved. The results are validated based on simulation of a two-area test system.
|
|
| 15. |
- Chamorro Vera, Harold Rene, et al.
(författare)
-
A network control system for hydro plants to counteract the non-synchronous generation integration
- 2019
-
Ingår i: International Journal of Electrical Power & Energy Systems. - : Elsevier. - 0142-0615 .- 1879-3517. ; 105, s. 404-419
-
Tidskriftsartikel (refereegranskat)abstract
- Sweden, a country with abundant hydro power, has expectations to include more wind power into its electrical system. Currently, in order to improve the frequency response requirements of its electrical system, the country is considering upgrading its hydro-governors. This effort is part of maintaining the system frequency and reaction within their limits following any disturbance events. To partially compensate for increased frequency fluctuations due to an increased share of renewables on its system, the frequency response of hydro-governors should be improved. This paper proposes an innovative network control system, through a supplementary control, for the improvement of the hydro-governor's action. This supplementary control allows having more flexibility over the control action and improves the primary frequency control, and thereby the overall system frequency response. The proposed supplementary control, based on an evolutionary game theory strategy, uses remote measurements and a hierarchical dynamic adjustment of the control. Additionally, in order to guarantee an optimal response, a Simulated Annealing Algorithm (SAA) is combined with the supplementary control. This paper illustrates the analysis and design of the proposed methodology, and is tested on two power systems models: (i) an aggregated model that represents the frequency response of Sweden, Norway and Finland, and (ii) The Nordic 32 test system.
|
|
| 16. |
- Chamorro Vera, Harold Rene, et al.
(författare)
-
Information Length Quantification and Forecasting of Power Systems Kinetic Energy
- 2022
-
Ingår i: IEEE Transactions on Power Systems. - : Institute of Electrical and Electronics Engineers (IEEE). - 0885-8950 .- 1558-0679. ; 37:6, s. 4473-4484
-
Tidskriftsartikel (refereegranskat)abstract
- Power systems operation and planning are facing several short-coming challenges due to the large inclusion of non-synchronous generation and the constant expansion of the electrical network. One of these challenges corresponds to the monitoring and forecasting of power systems Kinetic Energy (KE) to show on-line additional information for the Transmission System Operators (TSOs). In view of this challenge, KE monitoring requires innovative methods to analyse the continuous fluctuations in the system. Moreover, KE forecasting can foresee the status of the strength to overcome further events. In this work, we propose the use of information theory (specifically the concept of information length) as a way to provide useful insight in the power system KE variability and to demonstrate its usage as a starting point in decision making for power systems management. Additionally, a short-period forecasting using a Long Short Term Memory (LSTM) neural network model is proposed to estimate the value of information length in real time. The methodology is applied to a monthly collected data from the Nordic Power System. Results show that our method provides an effective description of the seasonal statistical variability.
|
|
| 17. |
- Chamorro Vera, Harold Rene, et al.
(författare)
-
Power system coherency recognition and islanding: Practical limits and future perspectives
- 2022
-
Ingår i: IET Energy Systems Integration. - : Institution of Engineering and Technology (IET). - 2516-8401. ; n/a
-
Tidskriftsartikel (refereegranskat)abstract
- Abstract Electrical power systems are continuously upgrading into networks with a higher degree of automation capable of identifying and reacting to different events that may trigger undesirable situations. In power systems with decreasing inertia and damping levels, poorly damped oscillations with sustained or growing amplitudes following a disturbance may eventually lead to instability and provoke a major event such as a blackout. Additionally, with the increasing and considerable share of renewable power generation, unprecedented operational challenges shall be considered when proposing protection schemes against unstable electro-mechanical (e.g. ringdown) oscillations. In an emergency situation, islanding operations enable splitting a power network into separate smaller networks to prevent a total blackout. Due to such changes, identifying the underlying types of oscillatory coherency and the islanding protocols are necessary for a continuously updating process to be incorporated into the existing power system monitoring and control tasks. This paper examines the existing evaluation methods and the islanding protocols as well as proposes an updated operational guideline based on the latest data-analytic technologies.
|
|
| 18. |
|
|
| 19. |
- Martinez-Majander, N., et al.
(författare)
-
Rivaroxaban versus aspirin for secondary prevention of ischaemic stroke in patients with cancer: a subgroup analysis of the NAVIGATE ESUS randomized trial
- 2020
-
Ingår i: European Journal of Neurology. - : Wiley. - 1351-5101 .- 1468-1331. ; 27:5, s. 841-848
-
Tidskriftsartikel (refereegranskat)abstract
- Background and purpose Cancer is a frequent finding in ischaemic stroke patients. The frequency of cancer amongst participants in the NAVIGATE ESUS randomized trial and the distribution of outcome events during treatment with aspirin and rivaroxaban were investigated. Methods Trial participation required a recent embolic stroke of undetermined source. Patients' history of cancer was recorded at the time of study entry. During a mean follow-up of 11 months, the effects of aspirin and rivaroxaban treatment on recurrent ischaemic stroke, major bleeding and all-cause mortality were compared between patients with cancer and patients without cancer. Results Amongst 7213 randomized patients, 543 (7.5%) had cancer. Of all patients, 3609 were randomized to rivaroxaban [254 (7.0%) with cancer] and 3604 patients to aspirin [289 (8.0%) with cancer]. The annual rate of recurrent ischaemic stroke was 4.5% in non-cancer patients in the rivaroxaban arm and 4.6% in the aspirin arm [hazard ratio (HR) 0.98, 95% confidence interval (CI) 0.78-1.24]. In cancer patients, the rate of recurrent ischaemic stroke was 7.7% in the rivaroxaban arm and 5.4% in the aspirin arm (HR 1.43, 95% CI 0.71-2.87). Amongst cancer patients, the annual rate of major bleeds was non-significantly higher for rivaroxaban than aspirin (2.9% vs. 1.1%; HR 2.57, 95% CI 0.67-9.96; P for interaction 0.95). All-cause mortality was similar in both groups. Conclusions Our exploratory analyses show that patients with embolic stroke of undetermined source and a history of cancer had similar rates of recurrent ischaemic strokes and all-cause mortality during aspirin and rivaroxaban treatments and that aspirin appeared safer than rivaroxaban in cancer patients regarding major bleeds. (NCT02313909).
|
|
| 20. |
|
|
| 21. |
- Zand, M., et al.
(författare)
-
Using adaptive fuzzy logic for intelligent energy management in hybrid vehicles
- 2020
-
Ingår i: 2020 28th Iranian Conference on Electrical Engineering, ICEE 2020. - : Institute of Electrical and Electronics Engineers (IEEE).
-
Konferensbidrag (refereegranskat)abstract
- Nowadays, hybrid vehicles have attracted major attention of researchers due to their capabilities to reduce consumption of fossil fuel, decrease air pollution and improve energy and environment sustainability. One of the most important challenges in production of hybrid vehicles is the optimal design of the energy management system in order to reduce energy consumption and costs. In this paper, an adaptive fuzzy logic based energy management scheme is proposed for a combined power generation system containing FC (FC), battery and ultracapacitor. In the mentioned system, the FC is the main source while both the battery and ultra-capacitor are used as auxiliary sources of energy. To evaluate performance of the proposed energy management scheme, ADVISOR toolbox in Matlab software is utilized for modelling different parts of the hybrid vehicle. Furthermore, to adjust scaling factors of the proposed system in order to reduce both the speed and fuel consumption errors, the Social Spider Algorithm (SSA) is suggested. The simulation results in Matlab verify that the proposed method provides a better performance than the well-known Power Tracking Control (PTC) system because this scheme updates its parameters online. Moreover, it reduces fuel consumption and tracks the reference speed better in comparison with PTC.
|
|
| 22. |
- Acosta, Martha N., et al.
(författare)
-
Assessment of Daily Cost of Reactive Power Procurement by Smart Inverters
- 2021
-
Ingår i: Energies. - : Multidisciplinary Digital Publishing Institute. - 1996-1073. ; 14:16
-
Tidskriftsartikel (refereegranskat)abstract
- The reactive power control mechanisms at the smart inverters will affect the voltage profile, active power losses and the cost of reactive power procurement in a different way. Therefore, this paper presents an assessment of the cost–benefit relationship obtained by enabling nine different reactive power control mechanisms at the smart inverters. The first eight reactive power control mechanisms are available in the literature and include the IEEE 1547−2018 standard requirements. The ninth control mechanism is an optimum reactive power control proposed in this paper. It is formulated to minimise the active power losses of the network and ensure the bus voltages and the reactive power of the smart inverter are within their allowable limits. The Vestfold and Telemark distribution network was implemented in DIgSILENT PowerFactory and used to evaluate the reactive power control mechanisms. The reactive power prices were taken from the default payment rate document of the National Grid. Simulation results demonstrate that the optimal reactive power control mechanism provides the best cost–benefit for the daily steady-state operation of the network.
|
|
| 23. |
|
|
| 24. |
- Alvarez-Rodriguez, Manuel, et al.
(författare)
-
Effect of length of time post-mortem on quality and freezing capacity of Cantabric chamois (Rupicapra pyrenaica parva) epididymal spermatozoa
- 2018
-
Ingår i: Animal Reproduction Science. - : ELSEVIER SCIENCE BV. - 0378-4320 .- 1873-2232. ; 198, s. 184-192
-
Tidskriftsartikel (refereegranskat)abstract
- Genome Resource Banks are keystones in the ex-situ conservation of wild species. Post-mortem (PM) collection of epididymal spermatozoa is an opportunistic and valuable source of germplasm, the time from the death of the animal limits its use. Seeking to improve germplasm preservation strategies for the chamois (Rupicapra sp.), the effect of PM time on epididymal sperm quality and freezability was studied using the Cantabrian chamois. Samples were classified according to PM collection time, up to 216 h (refrigerated), and cryopreserved (Tris-citric acid-fructose, 430 mOsm/kg, 15% egg yolk, 8% glycerol; freezing at - 20 degrees C/min). Sperm quality was assessed after recovery and post-thawing (motility by CASA, HOS test, abnormal forms, cytoplasmic droplets, and viability and acrosomal damage by flow cytometry). The sperm mass pH and osmolality showed a positive correlation with time. Total sperm motility dropped after 2 days PM, with progressivity and sperm velocities remained similar up to 3 days PM. Sperm freezability was acceptable, with the post-thawing HOST, motility, progressivity, VAP, VCL, VSL and BCF negatively correlating with PM time. Overall, chamois epidydimal samples were not adequate for preservation after 6 days PM. Freezability capacity could make these spermatozoa suitable for specific ART even if kept refrigerated for several days PM.
|
|
| 25. |
|
|
| 26. |
- Barco-Jimenez, John, et al.
(författare)
-
In-line Distributed Dispatch of Active and Reactive Power based on ADMM and Consensus Considering Battery Degradation in Microgrids
- 2023
-
Ingår i: IEEE Access. - : Institute of Electrical and Electronics Engineers (IEEE). - 2169-3536. ; 11, s. 31479-31495
-
Tidskriftsartikel (refereegranskat)abstract
- This work presents a distributed in-line strategy to manage an isolated microgrid by optimizing active and reactive power dispatch. The proposed objective function leads to minimize the operation costs and addresses some technical requirements such as diminishing power losses and voltage deviation. Additionally, the strategy deals with temporal multi-scale goals, i.e., robustness to demand disturbances and variation of renewable resources (a short-term objective), and preservation of the health of battery-based storage systems (a long-term objective). The technique uses alternating directions method of multipliers (ADMM), accelerated consensus, and a novel battery degradation model (Quadratic AH-Throughput model). We test the proposed solution in a case study that includes renewable resources and lead-acid and lithium batteries. To obtain the results of the case study, we employ a co-simulation scheme that uses Matlab and DIgSILENT. Finally, the performance of the method is compared with a centralized optimization technique.
|
|
| 27. |
- Bayona, Jhon F., et al.
(författare)
-
A High Efficiency Fluorescent Lamp Electronic Ballast Design
- 2016
-
Ingår i: IEEE CACIDI 2016 - IEEE Conference on Computer Sciences. - : Institute of Electrical and Electronics Engineers (IEEE). - 9781509029389
-
Konferensbidrag (refereegranskat)abstract
- This paper presents the design and implementation of an electronic ballast for powering a fluorescent lamp. The purpose of this work is to improve the efficiency of the ballast by implementing a Series Resonant Inverter (SRI) in half-bridge configuration instead classic Series-Parallel Resonant (SPRI); in order to allow to provide the voltage steady state of the lamp. By other hand, this DC-AC converter will supply the voltage lamp ignition. Results on the proposed experimental prototype, using a fluorescent lamp of 32W, shows a better efficiency compared to traditional SPRI configurations.
|
|
| 28. |
- Bayona, Jhon F., et al.
(författare)
-
Linear Control of a Power Factor Correction Rectifier in Half-bridge Configuration
- 2016
-
Ingår i: IEEE CACIDI 2016 - IEEE CONFERENCE ON COMPUTER SCIENCES. - : IEEE. - 9781509029389
-
Konferensbidrag (refereegranskat)abstract
- This paper presents a detailed analysis of a single phase high power factor boost half-bridge rectifier (RPFU-HBB). The purpose of this work is to achieve a unity power factor with tight-regulated output voltage. Using the experimental prototype for 120 Vrms input voltage, output power 80W and output voltage of 450V; a power factor of 0.99 and total harmonic distortion of 2.5% was obtained. In order to eliminate the unbalance voltage of the two output capacitors a special control scheme was developed. Modeling, theoretical linearization around the operating point of the RPFU-HBB, design considerations of the current controller output voltage by means of average current method and experimental work tested through simulation model RPFU-HBB are presented.
|
|
| 29. |
- Bousser, MG, et al.
(författare)
-
Rationale and design of a randomized, double-blind, parallel-group study of terutroban 30 mg/day versus aspirin 100 mg/day in stroke patients: the prevention of cerebrovascular and cardiovascular events of ischemic origin with terutroban in patients with a history of ischemic stroke or transient ischemic attack (PERFORM) study
- 2009
-
Ingår i: Cerebrovascular diseases (Basel, Switzerland). - : S. Karger AG. - 1421-9786 .- 1015-9770. ; 27:5, s. 509-518
-
Tidskriftsartikel (refereegranskat)abstract
- <i>Background:</i> Ischemic stroke is the leading cause of mortality worldwide and a major contributor to neurological disability and dementia. Terutroban is a specific TP receptor antagonist with antithrombotic, antivasoconstrictive, and antiatherosclerotic properties, which may be of interest for the secondary prevention of ischemic stroke. This article describes the rationale and design of the Prevention of cerebrovascular and cardiovascular Events of ischemic origin with teRutroban in patients with a history oF ischemic strOke or tRansient ischeMic Attack (PERFORM) Study, which aims to demonstrate the superiority of the efficacy of terutroban versus aspirin in secondary prevention of cerebrovascular and cardiovascular events. <i>Methods and Results:</i> The PERFORM Study is a multicenter, randomized, double-blind, parallel-group study being carried out in 802 centers in 46 countries. The study population includes patients aged ≥55 years, having suffered an ischemic stroke (≤3 months) or a transient ischemic attack (≤8 days). Participants are randomly allocated to terutroban (30 mg/day) or aspirin (100 mg/day). The primary efficacy endpoint is a composite of ischemic stroke (fatal or nonfatal), myocardial infarction (fatal or nonfatal), or other vascular death (excluding hemorrhagic death of any origin). Safety is being evaluated by assessing hemorrhagic events. Follow-up is expected to last for 2–4 years. Assuming a relative risk reduction of 13%, the expected number of primary events is 2,340. To obtain statistical power of 90%, this requires inclusion of at least 18,000 patients in this event-driven trial. The first patient was randomized in February 2006. <i>Conclusions:</i> The PERFORM Study will explore the benefits and safety of terutroban in secondary cardiovascular prevention after a cerebral ischemic event.
|
|
| 30. |
|
|
| 31. |
|
|
| 32. |
|
|
| 33. |
|
|
| 34. |
- Chamorro, H. R., et al.
(författare)
-
Data-driven trajectory prediction of grid power frequency based on neural models
- 2021
-
Ingår i: Electronics. - : MDPI AG. - 2079-9292. ; 10:2
-
Tidskriftsartikel (refereegranskat)abstract
- Frequency in power systems is a real-time information that shows the balance between generation and demand. Good system frequency observation is vital for system security and pro-tection. This paper analyses the system frequency response following disturbances and proposes a data-driven approach for predicting it by using machine learning techniques like Nonlinear Autoregressive (NAR) Neural Networks (NN) and Long Short Term Memory (LSTM) networks from simulated and measured Phasor Measurement Unit (PMU) data. The proposed method uses a horizon-window that reconstructs the frequency input time-series data in order to predict the frequency features such as Nadir. Simulated scenarios are based on the gradual inertia reduction by including non-synchronous generation into the Nordic 32 test system, whereas the PMU collected data is taken from different locations in the Nordic Power System (NPS). Several horizon-windows are experimented in order to observe an adequate margin of prediction. Scenarios considering noisy signals are also evaluated in order to provide a robustness index of predictability. Results show the proper performance of the method and the adequate level of prediction based on the Root Mean Squared Error (RMSE) index. © 2021 by the authors.
|
|
| 35. |
- Chamorro, Harold R., et al.
(författare)
-
Impact of Non-Synchronous Generation on Transmission Oscillations Paths
- 2018
-
Ingår i: 2018 IEEE Texas Power and Energy Conference (TPEC). - : Institute of Electrical and Electronics Engineers (IEEE). - 9781538610060
-
Konferensbidrag (refereegranskat)abstract
- The large scale penetration of non-synchronous generation has been causing several impacts on the power systems dynamics. The low-frequency oscillations affect the power exchanged along the transmission lines/corridors. This paper uses the Multi-Prony Analysis mode estimation technique to monitor and suggest the dominant oscillation modes which can be useful for wide-area control purposes. Moreover, the oscillation modes are also monitored under gradual cases of non-synchronous generation integration in the system. The methodology is applied to two different test transmission systems: i) the two area system and, ii) the Nordic 32 system. The results illustrate the similarity and differences in the scenarios proposed.
|
|
| 36. |
- Chamorro, Harold R., et al.
(författare)
-
Non-synchronous generation impact on power systems coherency
- 2016
-
Ingår i: IET Generation, Transmission & Distribution. - : Institution of Engineering and Technology. - 1751-8687 .- 1751-8695. ; 10:10, s. 2443-2453
-
Tidskriftsartikel (refereegranskat)abstract
- The increasing integration of renewables into the grid based on power electronics converters interfaces is affecting the power systems dynamics, requiring effective monitoring and visualisation to provide appropriate assessment during extreme events. The coherent group identification in power systems is of importance for dynamic studies and transmission capability improvement. This study analyses the coherency based on the mode shapes, the application of the Koopman mode analysis (KMA) and a Prony analysis (PA) on-line variation for the identification of coherent groups in power systems. KMA and PA use the voltage angle measurements obtained from simulation. The clustering of the coherent groups are evaluated in two test systems. The coherency methods are also evaluated taking into account the impact of a large gradual scale inclusion of non-synchronous generation under different penetration level cases. From the comparison and visualisation of the different methods it is possible to observe the impact of the large inclusion of non-synchronous generation on the coherency.
|
|
| 37. |
- Chamorro, Harold R., et al.
(författare)
-
On-line Oscillations Monitoring under High Penetration of Non-Synchronous Generation
- 2015
-
Ingår i: 2015 IEEE INTERNATIONAL CONFERENCE ON SMART GRID COMMUNICATIONS (SMARTGRIDCOMM). - : IEEE. - 9781467382892 ; , s. 278-282
-
Konferensbidrag (refereegranskat)abstract
- The large scale penetration of non-synchronous generation based power electronics converters interfaces in current power systems is modifying their dynamic characteristics. The observation, monitoring and supervision of the electromechanical oscillation changes due to this integration is a requirement in order to protect the system from undesired events. This paper uses the Prony analysis to estimate the critical modes by using the tie-lines which interconnect the operative areas as measurement points and evaluating the impact of the large gradual scale inclusion of non-synchronous generation on power systems. The modes monitoring involved in the transient dynamic response are shown in the different penetration level cases. From the computed measurements, the frequency and damping variation in the different cases studied on the test system is obtained, which shows the impact of the large inclusion of non-synchronous generation.
|
|
| 38. |
- Chamorro Vera, Harold Rene, et al.
(författare)
-
Coherency Estimation in Power Systems : A Koopman Operator Approach
- 2019
-
Ingår i: Springer Optimization and Its Applications. - Cham : Springer International Publishing. - 9783030254452 - 9783030254469 ; , s. 201-225
-
Bokkapitel (refereegranskat)abstract
- Integrating a significant amount of non-synchronous generation into power systems creates new technical challenges for transmission systems. The research and understanding of the impact of the non-synchronous generation through back-to-back Full Rated Converters’ (FRCs) on power system’s coherency is a matter of importance. Coherency behavior under the presence of large inclusion of non-synchronous generation requires more research, in order to understand the forming groups, after a disturbance, when the inertia is decreasing due to the decoupling. This document presents the application of the so-called Koopman Operator for the identification of coherent groups in power systems with the influence of non-synchronous generation. The Koopman Analysis clusters the coherent groups based on the measurements obtained. The visualization of the coherent groups identified allows to observe their dynamic variations according to the penetration level or fault location. The applied method of coherency identification is evaluated in the Nordic test system through gradually increasing integration of non-synchronous generations and different fault scenarios.
|
|
| 39. |
|
|
| 40. |
- Cortes-Caicedo, Brandon, et al.
(författare)
-
Application of the Vortex Search Algorithm to the Phase-Balancing Problem in Distribution Systems
- 2021
-
Ingår i: Energies. - : Multidisciplinary Digital Publishing Institute. - 1996-1073. ; 14:5
-
Tidskriftsartikel (refereegranskat)abstract
- This article discusses the problem of minimizing power loss in unbalanced distribution systems through phase-balancing. This problem is represented by a mixed-integer nonlinearprogramming mathematical model, which is solved by applying a discretely encoded Vortex Search Algorithm (DVSA). The numerical results of simulations performed in IEEE 8-, 25-, and 37-node test systems demonstrate the applicability of the proposed methodology when compared with the classical Cuh & Beasley genetic algorithm. In addition, the computation times required by the algorithm to find the optimal solution are in the order of seconds, which makes the proposed DVSA a robust, reliable, and efficient tool. All computational implementations have been developed in the MATLAB® programming environment, and all the results have been evaluated in DigSILENT© software to verify the effectiveness and the proposed three-phase unbalanced power-flow method.
|
|
| 41. |
- Engberg, GR, et al.
(författare)
-
Expansion of Submucosal Bladder Wall Tissue In Vitro and In Vivo
- 2016
-
Ingår i: BioMed research international. - : Hindawi Limited. - 2314-6141 .- 2314-6133. ; 2016, s. 5415012-
-
Tidskriftsartikel (refereegranskat)abstract
- In order to develop autologous tissue engineering of the whole wall in the urinary excretory system, we studied the regenerative capacity of the muscular bladder wall. Smooth muscle cell expansion on minced detrusor musclein vitroandin vivowith or without urothelial tissue was studied. Porcine minced detrusor muscle and urothelium were culturedin vitrounder standard culture conditions for evaluation of the explant technique and in collagen for tissue sectioning and histology. Autografts of minced detrusor muscle with or without minced urothelium were expanded on 3D cylinder moulds by grafting into the subcutaneous fat of the pig abdominal wall. Moulds without autografts were used as controls. Tissue harvesting, mincing, and transplantation were performed as a one-step procedure. Cells from minced detrusor muscle specimens migrated and expandedin vitroon culture plastic and in collagen.In vivostudies with minced detrusor autografts demonstrated expansion and regeneration in all specimens. Minced urothelium autografts showed multilayered transitional urothelium when transplanted alone but not in cotransplantation with detrusor muscle; thus, minced bladder mucosa was not favored by cografting with minced detrusor. No regeneration of smooth muscle or epithelium was seen in controls.
|
|
| 42. |
- Engberg, GR, et al.
(författare)
-
Transplantation of autologous minced bladder mucosa for a one-step reconstruction of a tissue engineered bladder conduit
- 2013
-
Ingår i: BioMed research international. - : Hindawi Limited. - 2314-6141 .- 2314-6133. ; 2013, s. 212734-
-
Tidskriftsartikel (refereegranskat)abstract
- Surgical intervention is sometimes needed to create a conduit from the abdominal wall to the bladder for self-catheterization. We developed a method for tissue engineering a conduit for bladder emptying withoutin vitrocell culturing as a one-step procedure. In a porcine animal model bladder, wall tissue was excised and the mucosa was minced to small particles. The particles were attached to a tube in a 1 : 3 expansion rate with fibrin glue and transplanted back by attaching the tube to the bladder and through the abdominal wall. Sham served as controls. After 4-5 weeks, conduits were assessed in respect to macroscopic and microscopic appearance in 6 pigs. Two pigs underwent radiology before termination. Gross examination revealed a patent conduit with an opening to the bladder. Histology and immunostaining showed a multilayered transitional uroepithelium in all cases. Up to 89% of the luminal surface area was neoepithelialized but with a loose attachment to the submucosa. No epithelium was found in control animals. CT imaging revealed a patent channel that could be used for filling and emptying the bladder. Animals that experienced surgical complications did not form conduits. Minced autologous bladder mucosa can be transplanted around a tubular mold to create a conduit to the urinary bladder withoutin vitroculturing.
|
|
| 43. |
- Gutierrez, A, et al.
(författare)
-
Hardware-in-the-Loop based SysML for Model and Control Design of Interleaved Boost Converters
- 2014
-
Ingår i: 2014 IEEE 15TH WORKSHOP ON CONTROL AND MODELING FOR POWER ELECTRONICS (COMPEL). - : IEEE.
-
Konferensbidrag (refereegranskat)abstract
- This paper outlines the application of the HiLeS-RCP (High Level Specification of Embedded Systems - Rich Client Platform) to model and design controllers of interleaved boost converters using the Systems Modelling Language (SysML). HiLeS-RCP allows the transformation from SysML models to Petri nets for implementation in embedded hardware. As a result, these models based on SysML can be used in Hardware-in-the-Loop (HIL)applications. In addition, the formal transformation from SysML to Petri nets is intended for structural analysis of the designed controllers in order to avoid undesired behaviours after implementation. As a case of study, HiLeS-RCP is used to model and design a supervisory controller for interleaved boost converters. This supervisory controller is implemented in FPGA; furthermore, embedded real time tools are used to evaluate the supervisory controller performance. Finally, experimental results show that the proposed methodology based on SysML and Petri nets is suitable to design controllers for interleaved boost converters.
|
|
| 44. |
- Gutierrez, A., et al.
(författare)
-
Hardware-in-the-loop simulation of PV systems in micro-grids using SysML models
- 2015
-
Ingår i: 2015 IEEE 16th Workshop on Control and Modeling for Power Electronics. - : IEEE. - 9781467368476
-
Konferensbidrag (refereegranskat)abstract
- This paper outlines a methodology for modeling photovoltaic systems in embedded hardware. This methodology uses the HiLeS platform to transform SysML models in Petri nets and generate VHDL code. The proposed methodology is intended for Hardware-in-the-Loop simulations of power converters and PV panels in microgrids. In addition, this methodology allows the design of MPPT controllers for their direct implementation in FPGA.
|
|
| 45. |
- Gutierrez, A., et al.
(författare)
-
Supervisory Control for Interleaved Boost Converters using HiLeS-Designer
- 2014
-
Ingår i: 2014 16TH EUROPEAN CONFERENCE ON POWER ELECTRONICS AND APPLICATIONS (EPE'14-ECCE EUROPE). - : IEEE Press.
-
Konferensbidrag (refereegranskat)abstract
- This paper presents the application of HiLeS (High Level Specification of Embedded Systems) formalism to design a supervisory controller based on FPGA for interleaved boost converters. This controller is intended to increase the versatility and efficiency of interleaved boost converters. Furthermore, the proposed supervisory controller uses Petri nets for structural analysis and stability. HiLeS-Designer tool, which is a platform based on HiLeS formalism, is used to design and implement the supervisory controller in embedded hardware. This approach uses the digital component of VHDL-AMS code generated by the HiLeS-Designer tool to implement the supervisory controller in FPGA. Simulations and experimental results show that the proposed control strategy increases the operating range and efficiency of interleaved boost converters.
|
|
| 46. |
- Gutierrez, A., et al.
(författare)
-
SysML Methodology for HIL Implementation of PV Models
- 2015
-
Ingår i: 2015 17TH EUROPEAN CONFERENCE ON POWER ELECTRONICS AND APPLICATIONS (EPE'15 ECCE-EUROPE). - : IEEE. - 9789075815238
-
Konferensbidrag (refereegranskat)abstract
- This paper describes a methodology for implementing in FPGA models of photovoltaic panels for Hardware-in-the-Loop (HIL) and real-time simulations. The proposed methodology integrates numerical solutions, SysML diagrams and Petri nets for structural design and formal validation. In this study, photovoltaic cells have been modeled using the single diode circuit. The photovoltaic panel model is solved by the Newton-Raphson method, and the Lagrange remainder is employed to limit the iteration number. Results show suitable accuracy and performance of the proposed methodology.
|
|
| 47. |
- Herrera-Brinez, Maria Camila, et al.
(författare)
-
The Equivalence between Successive Approximations and Matricial Load Flow Formulations
- 2021
-
Ingår i: Applied Sciences. - : Multidisciplinary Digital Publishing Institute. - 1454-5101 .- 2076-3417. ; 11:7, s. 2905-
-
Tidskriftsartikel (refereegranskat)abstract
- This paper shows the equivalence of the matricial form of the classical backward/forward load flow formulation for distribution networks with the recently developed successive approximations (SA) load flow approach. Both formulations allow solving the load flow problem in meshed and radial distribution grids even if these are operated with alternating current (AC) or direct current (DC) technologies. Both load flow methods are completely described in this research to make a fair comparison between them and demonstrate their equivalence. Numerical comparisons in the 33- and 69-bus test feeder with radial topology show that both methods have the same number of iterations to find the solution with a convergence error defined as 1×10−10.
|
|
| 48. |
- Martínez-Pastor, Felipe, et al.
(författare)
-
Extender osmolality, glycerol and egg yolk on the cryopreservation of epididymal spermatozoa for gamete banking of the Cantabric Chamois (Rupicapra pyrenaica parva)
- 2019
-
Ingår i: Theriogenology. - : Elsevier. - 0093-691X .- 1879-3231. ; 125, s. 109-114
-
Tidskriftsartikel (refereegranskat)abstract
- Germplasm banking is a key technology enabling the ex-situ conservation of wild species. However, cryopreservation protocols must be tested to assure the applicability of the banked material. The objective of this study was defining a range of parameters for the composition of a semen extender for Cantabrian chamois epididymal spermatozoa (post-mortem collection). The freezing extender was based in a TES-Tris-fructose buffer, modifying its composition in three experiments: Osmolality of the buffer (320, 380 or 430 mOsm/kg, 8% glycerol, 15% egg yolk), glycerol (4 or 8%, 430 mOsm/kg, 15% egg yolk), egg yolk (10 or 15%, 430 mOsm/kg, 4% glycerol). Sperm was extended at 100 mill. spermatozoa/ml, cooled at 5 °C and frozen at -20 °C/min. Sperm quality was assessed pre and post-thawing (CASA, HOS test, abnormal forms, cytoplasmic droplets, and viability and acrosomal damage by flow cytometry). Freezability was good overall, with total motility of 65.5% ± 2.4 initial and 55.8% ± 2.4 post-thawing. The extenders affected the post-thaw sperm quality marginally. Whereas osmolalities and glycerol concentrations seemed not to differ, 430 mOsm/kg and 4% glycerol might be preferred. Egg yolk concentrations only differed on sperm velocity (VCL: 84.0 ± 6.7 μm/s in 10% vs. 70.7 ± 6.2 μm/s in 15%, P < 0.05). Our results suggest a good cryotolerance of chamois epididymal spermatozoa, with a preferred extender composition of hyperosmotic buffer, glycerol in the 4% range and lower egg yolk (10% range) than other ruminants.
|
|
| 49. |
- Marto, João Pedro, et al.
(författare)
-
Safety and Outcome of Revascularization Treatment in Patients With Acute Ischemic Stroke and COVID-19: The Global COVID-19 Stroke Registry.
- 2023
-
Ingår i: Neurology. - 1526-632X. ; 100:7
-
Tidskriftsartikel (refereegranskat)abstract
- COVID-19-related inflammation, endothelial dysfunction, and coagulopathy may increase the bleeding risk and lower the efficacy of revascularization treatments in patients with acute ischemic stroke (AIS). We aimed to evaluate the safety and outcomes of revascularization treatments in patients with AIS and COVID-19.This was a retrospective multicenter cohort study of consecutive patients with AIS receiving intravenous thrombolysis (IVT) and/or endovascular treatment (EVT) between March 2020 and June 2021 tested for severe acute respiratory syndrome coronavirus 2 infection. With a doubly robust model combining propensity score weighting and multivariate regression, we studied the association of COVID-19 with intracranial bleeding complications and clinical outcomes. Subgroup analyses were performed according to treatment groups (IVT-only and EVT).Of a total of 15,128 included patients from 105 centers, 853 (5.6%) were diagnosed with COVID-19; of those, 5,848 (38.7%) patients received IVT-only and 9,280 (61.3%) EVT (with or without IVT). Patients with COVID-19 had a higher rate of symptomatic intracerebral hemorrhage (SICH) (adjusted OR 1.53; 95% CI 1.16-2.01), symptomatic subarachnoid hemorrhage (SSAH) (OR 1.80; 95% CI 1.20-2.69), SICH and/or SSAH combined (OR 1.56; 95% CI 1.23-1.99), 24-hour mortality (OR 2.47; 95% CI 1.58-3.86), and 3-month mortality (OR 1.88; 95% CI 1.52-2.33). Patients with COVID-19 also had an unfavorable shift in the distribution of the modified Rankin score at 3 months (OR 1.42; 95% CI 1.26-1.60).Patients with AIS and COVID-19 showed higher rates of intracranial bleeding complications and worse clinical outcomes after revascularization treatments than contemporaneous non-COVID-19 patients receiving treatment. Current available data do not allow direct conclusions to be drawn on the effectiveness of revascularization treatments in patients with COVID-19 or to establish different treatment recommendations in this subgroup of patients with ischemic stroke. Our findings can be taken into consideration for treatment decisions, patient monitoring, and establishing prognosis.The study was registered under ClinicalTrials.gov identifier NCT04895462.
|
|
| 50. |
- Mayorga, J. L., et al.
(författare)
-
Development of real-time control emulator in FPGA using HiLeS methodology
- 2015
-
Ingår i: IECON 2015 - 41st Annual Conference of the IEEE Industrial Electronics Society. - : Institute of Electrical and Electronics Engineers (IEEE). - 9781479917624 ; , s. 4076-4081
-
Konferensbidrag (refereegranskat)abstract
- Embedded systems (ES) based on field programmable gate arrays (FPGAs) enhance the overall computational capability and relieve computational load. The lack on design and implementation methods for specific control functions in hardware limits the application of complex control techniques. Therefore, a design methodology approach is showed in the current work. Fuzzy, LQR, and PI control systems are modeled using HiLeS-RCP (High Level Specification of Embedded Systems-Rich Client Platform), a methodology that links the requirements formalization step using SySML and the virtual prototyping based on Petri Nets which takes place in the system design within the process of functional modeling, generating VHDL-AMS code to implement in FPGA.
|
|
