521 research outputs found

    Self-adaptive Controllers for Renewable Energy Communities Based on Transformer Loading Estimation

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    In this paper, self-adaptive controllers for renewable energy communities based on data-driven approach are proposed to mitigate the voltage rise and transformer congestion at the community level. In the proposed approach, the transformer loading percentage is estimated by the trained data-driven model, which uses the extreme gradient boosting regression algorithm based on a measurement set acquired from critical coupling points of the communities. To avoid voltage rise issues, the droop control parameters (i.e., voltage threshold for P - V, Q - V curves) are adaptively tuned based on the solar irradiance availability and estimated transformer loading. The proposed approach has been tested in the IEEE European LV distribution network. Results showed that the control approach could effectively reduce 22.2 % of the total overloaded instances, while still keeping voltage magnitude in the operation range. This method can help DSOs manage voltage violation and congestion without further communication

    Polyharmonic approximation on the sphere

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    The purpose of this article is to provide new error estimates for a popular type of SBF approximation on the sphere: approximating by linear combinations of Green's functions of polyharmonic differential operators. We show that the LpL_p approximation order for this kind of approximation is σ\sigma for functions having LpL_p smoothness σ\sigma (for σ\sigma up to the order of the underlying differential operator, just as in univariate spline theory). This is an improvement over previous error estimates, which penalized the approximation order when measuring error in LpL_p, p>2 and held only in a restrictive setting when measuring error in LpL_p, p<2.Comment: 16 pages; revised version; to appear in Constr. Appro

    Assessing Dietary Branched-Chain Amino Acids to Achieve Linear Programming Goals through Model Extrapolation and Empirical Research

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    Renewed interest, especially in the United States, has sparked in assessing branched-chain amino acid interactions in practical diets for broilers. Indeed, as L-valine enters formulation bird nitrogen excesses are reduced as diet protein falls to the new first limiting amino acid (e.g., isoleucine, arginine, or tryptophan). For a United States based example, the result is less oilseeds and more gains, which typically result in increased inclusions in corn or corn by-products, coupled with a concomitant increase in dietary leucine. The proceedings outline the foundations of the branched-chain amino acid early research, antagonism studies, and a meta-analysis conducted on publications with Cobb and Ross birds from 2000 to present. Results indicate that branched-chain amino acid interactions can occur in broilers fed on practical diets, and that responses vary by strain

    10 Mb/s visible light transmission system using a polymer light-emitting diode with orthogonal frequency division multiplexing

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    We present a newly designed polymer light-emitting diode with a bandwidth of ∌350 kHz for high-speed visible light communications. Using this new polymer light-emitting diode as a transmitter, we have achieved a record transmission speed of 10 Mb/s for a polymer light-emitting diode-based optical communication system with an orthogonal frequency division multiplexing technique, matching the performance of single carrier formats using multitap equalization. For achieving such a high data-rate, a power pre-emphasis technique was adopted

    Environmental allergen reduction in asthma management: an overview

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    Asthma is a prevalent non-communicable disease that affects both children and adults. Many patients with severe, uncontrolled asthma could not achieve total control despite using anti-asthmatic drugs. There is increasing evidence that allergy to environmental allergens, including both indoor and outdoor allergens, is associated with asthma symptoms and severe asthma. Frequently reported sensitized allergens were dust mites, cockroaches, grass pollens, molds, pets, and rodents in allergic asthma patients, although the patterns of widespread allergens differed from each country. Allergen avoidance is the cornerstone of asthma management, especially in sensitized subjects. This review summarizes environmental allergen avoidance and clarifies their effects on asthma control. Despite contrasting results about the impact of allergen exposure reduction on asthma control, several studies supported the beneficial effects of reducing asthma-related symptoms or risk of exacerbations as a nondrug therapy. Identifying environmental allergens is helpful for asthma patients, and further studies on clinically effective avoidance methods are required

    Victimisation, poly-victimisation and health-related quality of life among high school students in Vietnam: a cross-sectional survey

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    BACKGROUND: In high and upper-middle income countries poly-victimisation (exposure to multiple forms of victimisation) is associated with worse health-related quality of life (HRQoL) among adolescents. There is a lack of empirical evidence about these associations from low- and lower-middle income countries. The aims of this study were to examine the associations between exposure to 1) individual forms of victimisation and 2) poly-victimisation and the HRQoL of adolescents in Vietnam. METHOD: A cross-sectional, anonymously-completed survey of high school students in Hanoi, Vietnam. Lifetime exposure to eight individual forms of victimisation and poly-victimisation were assessed using the Juvenile Victimisation Questionnaire Revised-2 (JVQ R2). Health-related quality of life was assessed using the Duke Health Profile Adolescent Version (DHP-A). Bi-variate analyses and multiple linear regressions were conducted to assess the associations between individual forms of victimisation, poly-victimisation and HRQoL among girls and boys. RESULTS: In total 1616/1745 students (92.6&nbsp;%) completed the questionnaire. Adolescent girls had significantly worse HRQoL than boys in all domains, except disability. Different forms of victimisation were associated with different HRQoL domains among girls and boys. Cyber victimisation was the most detrimental to girls\u27 HRQoL while for boys maltreatment was the most detrimental. Experiences of poly-victimisation were associated with worse HRQoL in physical, mental, social and general health, lower levels of self-esteem and increased levels of anxiety, depression and pain domains among both sexes. CONCLUSIONS: Among Vietnamese adolescents, experiences of individual forms of victimisation were associated with poorer HRQoL in specific domains; the most detrimental forms of victimisation varied for girls and boys. However, it was experiences of poly-victimisation that had the most detrimental impacts on the HRQoL of both sexes. Recognition of violence, including poly-victimisation, is still low in Vietnam. These data indicate that community education, prevention and early intervention programs to reduce violent victimisation and assist adolescents who have experienced it, with attention to gender differences, are needed in Vietnam

    Poly-victimisation and health risk behaviours, symptoms of mental health problems and suicidal thoughts and plans among adolescents in Vietnam

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    BACKGROUND: Limited evidence is available about poly-victimisation (exposure to multiple forms of victimisation) and mental health among adolescents in low and lower-middle-income countries. The aim of this study was to examine the associations between lifetime exposure to poly-victimisation, health risk behaviours, symptoms of common mental health problems and suicidal ideas in the previous year among high school students in Vietnam. METHODS: Participants were high school students in rural and urban districts of Hanoi, Vietnam. The data source was an anonymously-completed structured self-report survey. Lifetime exposure to poly-victimisation was assessed using the juvenile victimisation questionnaire revised 2 (JVQ R-2); mental health symptoms by the depression, anxiety and stress scale-21 (DASS-21); involvement in health risk behaviours and previous year suicidal thoughts and plans by questions adapted from the 2013 youth risk behaviour survey. Data were collected between October, 2013 and January, 2014 and were analysed using generalised structural equation modelling. RESULTS: In total 1616/1745 (92.6 %) eligible students provided complete data. Prior year suicidal thoughts were reported by 21.4 % (95 % CI 18.5–24.5 %) of the female respondents and 7.9 % (95 % CI 6.2–9.8 %) of the male respondents. Prior year suicidal plans were reported by 7.8 % (95 % CI 5.9–9.8 %) of the girls and 4.0 % (95 % CI 2.7–5.3 %) of the boys. Poly-victimisation was associated with increased likelihood of involvement in health risk behaviours and symptoms of common mental health problems among both sexes, which increased adolescents’ risk of having suicidal ideas in the previous year. Compared to non-victims or victims of fewer forms, poly-victims were also more likely to report suicidal thoughts and plans among both girls and boys (p < 0.05). CONCLUSIONS: Overall, the results revealed that poly-victimisation was associated with increased involvement in health risk behaviours, poorer mental health and increased risks of suicidal ideas among Vietnamese adolescents. Suicidal ideas were prevalent among the students. Interventions to assist victims of violence and prevention of violence, especially poly-victimisation, among adolescents in Vietnam is therefore important

    A 10 Mb/s visible light communication system using a low bandwidth polymer light-emitting diode

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    In this paper we experimentally demonstrate a 10 Mb/s error free visible light communications (VLC) system using polymer light-emitting diodes (PLEDs) for the first time. The PLED under test is a blue emitter with ∌600 kHz bandwidth. Having such a low bandwidth means the introduction of an intersymbol interference (ISI) induced penalty at higher transmission speeds and thus the requirement for an equalizer. In this work we improve on previous literature by implementing a decision feedback equalizer, rather than a linear equalizer. Considering 7% and 20% forward error correction codes, transmission speeds up to ∌12 Mb/s can be supported

    Multi-band carrier-less amplitude and phase modulation for bandlimited visible light communications systems

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    Visible light communications is a technology with enormous potential for a wide range of applications within next generation transmission and broadcasting technologies. VLC offers simultaneous illumination and data communications by intensity modulating the optical power emitted by LEDs operating in the visible range of the electromagnetic spectrum (~370-780 nm). The major challenge in VLC systems to date has been in improving transmission speeds, considering the low bandwidths available with commercial LED devices. Thus, to improve the spectral usage, the research community has increasingly turned to advanced modulation formats such as orthogonal frequency-division multiplexing. In this article we introduce a new modulation scheme into the VLC domain; multiband carrier-less amplitude and phase modulation (m-CAP) and describe in detail its performance within the context of bandlimited systems

    The CIPAZ study protocol: an open label randomised controlled trial of azithromycin versus ciprofloxacin for the treatment of children hospitalised with dysentery in Ho Chi Minh City, Vietnam

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    Background: Diarrhoeal disease remains a common cause of illness and death in children <5 years of age. Faecal-oral infection by Shigella spp. causing bacillary dysentery is a leading cause of moderate-to-severe diarrhoea, particularly in low and middle-income countries. In Southeast Asia, S. sonnei predominates and infections are frequently resistant to first-line treatment with the fluoroquinolone, ciprofloxacin. While resistance to all antimicrobials is increasing, there may be theoretical and clinical benefits to prioritizing treatment of bacillary dysentery with the azalide, azithromycin. In this study we aim to measure the efficacy of treatment with azithromycin compared with ciprofloxacin, the current standard of care, for the treatment of children with bacillary dysentery. Methods and analysis: We will perform a multicentre, open-label, randomized controlled trial of two therapeutic options for the antimicrobial treatment of children hospitalised with dysentery. Children (6–60 months of age) presenting with symptoms and signs of dysentery at Children’s Hospital 2 in Ho Chi Minh City will be randomised (1:1) to treatment with either oral ciprofloxacin (15mg/kg/twice daily for 3 days, standard-of-care) or oral azithromycin (10mg/kg/daily for 3 days). The primary endpoint will be the proportion of treatment failure (defined by clinical and microbiological parameters) by day 28 (+3 days) and will be compared between study arms by logistic regression modelling using treatment allocation as the main variable. Ethics and dissemination: The study protocol (version 1.2 dated 27th December 2018) has been approved by the Oxford Tropical Research Ethics Committee (47–18) and the ethical review boards of Children's Hospital 2 (1341/NĐ2-CĐT). The study has also been approved by the Vietnamese Ministry of Health (5044/QĐ-BYT). Trial registration: Clinicaltrials.gov: NCT03854929 (February 26th 2019)
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