Low-power wind energy conversion system with variable structure control for DC grids

This paper presents a discussion on the use of variable structure control, i.e., sliding mode control, for improving the dynamic control performance of a low-power wind energy conversion system (WECS) that is connected to a DC microgrid. The sliding mode control is applied to the wind turbine system to extract the maximum possible power from the wind, thus achieving the state of maximum power point tracking to reach the maximum power generation (MPG), and also applied to the power converter to reach the maximum power injection (MPI) to the load. The amount of energy extractable from a dynamically changing wind using the WECS with sliding mode control is compared with that of the classic PI controller. Simulation results show that for a dynamically changing wind, more energy can be harvested with the sliding mode control as compared to the PI control. © 2014 IEEE.published_or_final_versio

Nonlinear Dynamic Power Tracking of Low-Power Wind Energy Conversion System

This paper addresses the use of variable structure control (i.e., sliding mode (SM) control) for improving the dynamic performance of a low-power wind energy conversion system (WECS) that is connected to a dc grid. The SM control is applied to simultaneously match 1) the maximum power generation of the wind turbine system from the wind with 2) the maximum power injection of the grid-connected power converter into the grid. The amount of energy extractable from a dynamically changing wind using the WECS with SM control is compared with that of classic PI control. Both the simulation and experimental results show that more energy can be harvested with the SM control as compared to the PI control for any dynamically changing or random wind conditions

Breast cancer data analysis for survivability studies and prediction

© 2017 Elsevier B.V. Background Breast cancer is the most common cancer affecting females worldwide. Breast cancer survivability prediction is challenging and a complex research task. Existing approaches engage statistical methods or supervised machine learning to assess/predict the survival prospects of patients. Objective The main objectives of this paper is to develop a robust data analytical model which can assist in (i) a better understanding of breast cancer survivability in presence of missing data, (ii) providing better insights into factors associated with patient survivability, and (iii) establishing cohorts of patients that share similar properties. Methods Unsupervised data mining methods viz. the self-organising map (SOM) and density-based spatial clustering of applications with noise (DBSCAN) is used to create patient cohort clusters. These clusters, with associated patterns, were used to train multilayer perceptron (MLP) model for improved patient survivability analysis. A large dataset available from SEER program is used in this study to identify patterns associated with the survivability of breast cancer patients. Information gain was computed for the purpose of variable selection. All of these methods are data-driven and require little (if any) input from users or experts. Results SOM consolidated patients into cohorts of patients with similar properties. From this, DBSCAN identified and extracted nine cohorts (clusters). It is found that patients in each of the nine clusters have different survivability time. The separation of patients into clusters improved the overall survival prediction accuracy based on MLP and revealed intricate conditions that affect the accuracy of a prediction. Conclusions A new, entirely data driven approach based on unsupervised learning methods improves understanding and helps identify patterns associated with the survivability of patient. The results of the analysis can be used to segment the historical patient data into clusters or subsets, which share common variable values and survivability. The survivability prediction accuracy of a MLP is improved by using identified patient cohorts as opposed to using raw historical data. Analysis of variable values in each cohort provide better insights into survivability of a particular subgroup of breast cancer patients

The interplay between fluorescence and phosphorescence with luminescent gold(i) and gold(iii) complexes bearing heterocyclic arylacetylide ligands

published_or_final_versio

Present situation and characteristics of building energy consumption in Hong Kong

2004-2005 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Extending the Operating Range of Electric Spring using Back-To-Back Converter: Hardware Implementation and Control

This paper presents the first hardware implementation and control of an electric spring based on a back-to-back converter configuration. Because of its ability to provide both active and reactive power compensation, this back-to-back electric spring (ES-B2B) can substantially extend the operating range of the original version of the electric spring (ES-1) and provide enhanced voltage support and suppression functions. The hardware system and control of the ES-B2B have been successfully developed and tested. The experimental results have confirmed the effectiveness of the ES-B2B in supporting and suppressing the mains voltage. Particularly, the voltage suppression ability of the ES-B2B is superior over that of ES-1. The use of ES-B2B in a simulation study of a weak power grid has also been conducted. The ES-B2B has been found to be highly effective in mitigating voltage fluctuation caused by intermittent renewable power generation

Access to recreational physical activities by car and bus : an assessment of socio-spatial inequalities in mainland Scotland

Obesity and other chronic conditions linked with low levels of physical activity (PA) are associated with deprivation. One reason for this could be that it is more difficult for low-income groups to access recreational PA facilities such as swimming pools and sports centres than high-income groups. In this paper, we explore the distribution of access to PA facilities by car and bus across mainland Scotland by income deprivation at datazone level. GIS car and bus networks were created to determine the number of PA facilities accessible within travel times of 10, 20 and 30 minutes. Multilevel negative binomial regression models were then used to investigate the distribution of the number of accessible facilities, adjusting for datazone population size and local authority. Access to PA facilities by car was significantly (p<0.01) higher for the most affluent quintile of area-based income deprivation than for most other quintiles in small towns and all other quintiles in rural areas. Accessibility by bus was significantly lower for the most affluent quintile than for other quintiles in urban areas and small towns, but not in rural areas. Overall, we found that the most disadvantaged groups were those without access to a car and living in the most affluent areas or in rural areas

Expected Architects Acceptance of a BIM Tool to Optimize the Building Energetic Performance.

Universidade de Lisboa, Faculdade de Arquitetura, CIAUD, Rua Sá Nogueira, Pólo Universitário, Alto da Ajuda, 1349-055, Lisboa, Portugal - In Advances in Ergonomics in Design - Proceedings of the AHFE 2020 Virtual Conference on Ergonomics in DesignTITULO DO PROJETO: "Ren4EEnIEQ - Ferramenta estendida acoplada ao BIM para a melhoria da eficiência energética e qualidade do ambiente interior na renovação de edifícios", Cham,info:eu-repo/semantics/publishedVersio

Cooling load distribution of large space building

2003-2004 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Pay-it-forward dual gonorrhea/chlamydia test uptake among men who have sex with men in China: a pragmatic, quasi-experimental study

Background: Chinese men who have sex with men (MSM) rarely receive gonorrhea/chlamydia testing. The purpose of this pilot study was to evaluate a pay-it-forward strategy to increase gonorrhea/chlamydia testing among MSM. Pay-it-forward has one person receive a gift, then asks the same person if they would like to give a gift to another person. Methods: We used a quasi-experimental pragmatic study to compare a pay-it-forward model to standard of care at two HIV testing sites for MSM. A pay-it-forward program was implemented for three months, during which men were offered free gonorrhea/chlamydia testing and given the option of donating money toward testing for future participants. Both sites then switched to standard of care for three months, offering dual testing at the standard price. We compared test uptake and financial costs in the two groups. Findings: 408 men were included in this study. 203 men were offered pay-it-forward, and 205 were offered standard of care. Overall, 109 (109/203, 53·7%) men received gonorrhea/chlamydia testing in the pay-it-forward group and 12 (12/205, 5·9%) men received gonorrhea/chlamydia testing in the standard of care group (adjusted odds ratio 19·73, 95%CI 10·02-38·85). This was a first gonorrhea or chlamydia test for 86% (104/121) of men. 89% (97/109) of men in the pay-it-forward group donated some amount. The incremental unit cost per test in the pay-it-forward group was 67 USD, compared to 503 USD in the standard of care group. Interpretation: Pay-it-forward may be a sustainable model for expanding integrated HIV testing services among MSM in China