Control algorythm of a smart grid device for optimal radial feeder load reconfiguration

Abstract Secondary distribution network, generally speaking, performs as well as the performance of its LV feeders. The main problem a feeder is experiencing is the load unbalancing due to the stochastic nature of its individual single-phase loads: bigger losses in certain phase accompanied with bed voltage regulation and voltage unbalance. The aim of this paper is to address the issue of automatic balancing as progressing from the end of the feeder towards the front using smart device based on three-ways switch selector and artificial intelligence algorithm to minimize the neutral current

Novel heuristic and SVM based optimization algorithm for improving distribution feeder performance

Abstract: Secondary distribution networks generally perform as well as its LV feeders are performing. The main problem that a feeder is experiencing would be the load unbalancing due to the stochastic nature of its individual single-phase loads: larger losses in certain phases accompanied by bad voltage regulation and voltage unbalance. In order to address this problem, it may be economical to install apparatus to automatically balance or partially balance the loads progressing from the end of the feeder towards the front using smart devices based on a three-ways switch selector and an artificial intelligence algorithm to minimize the neutral current. The main idea behind this paper is therefore to keep the three phases progressively balanced along the whole length of the line. A Support Vector Machines (SVM) implementation and a heuristic method are presented as the numerical algorithm

Measuring monopole and dipole polarizability of acoustic meta-atoms

© 2018 Author(s). We present a method to extract monopole and dipole polarizability from experimental measurements of two-dimensional acoustic meta-atoms. In contrast to extraction from numerical results, this enables all second-order effects and uncertainties in material properties to be accounted for. We apply the technique to 3D-printed labyrinthine meta-atoms of a variety of geometries. We show that the polarizability of structures with a shorter acoustic path length agrees well with numerical results. However, those with longer path lengths suffer strong additional damping, which we attribute to the strong viscous and thermal losses in narrow channels

Life within chronic care: is this a service or sentence?

Background: Understanding the meaning of one’s lived experiences improves one’s understanding of what it means to be human, in association with the social, cultural and historical context in which being a human occurs. The authors in this study describe the lived experiences of residents within a chronic care facility including the practitioner and family perspectives.Methods: A qualitative approach was employed with a single-site, descriptive, instrumental case study design. Purposive sampling was utilised to select the chronic facility. Multiple sources of evidence included narratives, semi-structured interviews with staff, residents and family members, and activity profiles of the residents augmented by an ergonomic evaluation of the facility. Content analysis using within-case analysis was implemented.Results: The greatest impact on the quality of the resident’s lived experiences emanates from the physical, organisational and social environments in which they reside. Limited resources, poor staff attitudes and routines that are enforced both on the staff of the facility and the residents appear to reduce optimal functioning within the facility. Furthermore the residents’ intrinsic motivation, presence of enforced idleness, learned helplessness and institutionalisation is often intensified and becomes characteristic of the residents lived experiences.Discussion: The lived experiences of the residents are described according to quality of life indicators that were identified during the study and supported by literature. These include the influence of the physical, social and organizational environments on the residents’ functional status, which comprises physical well-being and emotional well-being and engagement in meaningful occupations including social interaction and relationships with other individuals.Conclusions: Findings of this study may be valuable in understanding and facilitating a positive change in service delivery within chronic care centres.Keywords: chronic care, institutionalisation, lived experiences, residents, occupational deprivatio

Regional clinical registry data show increased incidence of cutaneous melanoma in Cape Town

Cutaneous melanoma is a skin tumour that continues to result in a high mortality rate, particularly in the case of thick tumours and those that are deeply invasive histologically. It occurs in all populations but is most common in fair-skinned individuals, especially those with skin types 1 and 2 that tan poorly or not at all. There is epidemiological evidence for the pathogenetic role of ultraviolet light, particularly intense childhood exposure, although the relationship is complex. Genetic factors also play a role, as exemplified by families with both atypical naevi and melanoma. The rising incidence of melanoma, noted initially in countries with high levels of UV light, appears to be levelling off or decreasing in some areas. The pattern of these trends is inconsistent, with even European countries showing great variation. An epidemiological study performed in Cape Town from 1990 to 1995 demonstrated an incidence of melanoma of 24.4 per 100 000 white people per annum. We conducted a methodologically identical study in the same geographical area after a 10-year interval, to identify whether there is a trend in the incidence of melanoma in this area

Detecting asymptomatic coronary artery disease using routine exercise testing and exercise thallium scintigraphy in patients with atherosclerotic vascular disease

ECG-monitored exercise testing has been proposed as a relatively inexpensive and effective means of screening for asymptomatic coronary artery disease in patients presenting for peripheral vascular surgery. Despite the fact that exercise thallium scintigraphy is also dependent on the patient's ability to exercise, using this test in conjunction with ECG-monitored exercise testing may enhance sensitivity and specificity of non-invasive evaluation. Thirty-two patients were subjected to ECG-monitored exercise testing, exercise thallium scintigraphy and coronary angiography. The sensitivity of ECGmonitored exercise testing for detecting coronary artery disease was calculated at 81,8% and the specificity at 87,5%, while the figures for exercise thallium scintigraphy were 73,1% and 33,3% respectively. Using these two methods in combination yielded a predictive accuracy of 90,6%. The only advantage of exercise thallium scintigraphy over exercise ECG appears to be in patients in whom the latter test could not be interpreted or was non-diagnostic

Risk factors for atherosclerosis - can they be used to identify the patient with multisystem atherosclerosis?

Risk factors are often used in preventive care programmes to identify the patient at particular risk for developing atherosclerosis. Risk factors for atherosclerosis have also been shown to be linked to the presence of the disease at a given time, a fact that may be helpful when screening for additional atherosclerotic disease in the known arteriopath. Risk factors .were recorded in 471 patients admi"ed to hospital with symptoms of atherosclerosis. In patients admi"ed primarily with peripheral vascular disease, risk factors linked to the presence of additional coronary artery disease were a family history of ischaemic heart disease (odds ratio = 2,6), the presence of carotid artery disease (odds ratio = 1,9) and high fasting serum triglyceride levels (P < 0,04). Grouping these factors together usin.g logistic regression, ischaemic heart disease could be predicted with a sensitivity of 72% and a specificity of 43%. Patients admitted with carotid artery disease were more likely to have ischaemic heart disease in the presence of peripheral vascular disease (odds ratio = 1,9) and a raised serum cholesterol level (P < 0,02), while female gender (odds ratio = 2,9) and an increase in age (P< 0,001) were linked to an increased prevalence of concomitant atherosclerosis in patients admmed with acute myocardial infarction or for elective coronary artery bypass surgery. Using an age cut-off point, additional atherosclerosis could be predicted with a sensitivity of 32% and a specificity of 88% in these patients