DC link voltage control during sudden load changes in AC microgrids

Parallel inverters in AC microgrids can achieve accurate power sharing using droop control. However, different grid line impedances will result in different transient power and thus different energy being delivered or absorbed by the inverters during sudden load changes. This might lead the DC link voltage to rise beyond the trip limit causing the inverter to shut down, which reduces the reliability of the whole microgrid. This paper investigates the effect of the mismatch in line impedances on the stability of the DC link voltage during a sudden load changes and proposes a scheme to control the DC link voltage during disturbances. Simulation and experimental results are presented to verify the efficacy of the proposed controller

May Measurement Month 2017: an analysis of blood pressure screening results from the United Arab Emirates-Northern Africa and Middle East

Elevated blood pressure (BP) is a growing burden worldwide, leading to over 10 million deaths each year. May Measurement Month (MMM) is a global initiative aimed at raising awareness of high BP and to act as a temporary solution to the lack of screening programmes worldwide. United Arab Emirates has a young population, but cardiovascular disease (CVD) is the commonest cause of death (40%). Myocardial infarction and stroke occurs at least a decade earlier than in western countries. Previous screening in our young population showed that 85% of the population had at least one CVD risk factor and about 62% of them were unaware of it. An opportunistic cross-sectional survey of volunteers aged ≥18 was carried out in May 2017. Blood pressure measurement, the definition of hypertension and statistical analysis followed the standard MMM protocol. Screening was held in 23 sites such as mosques, sports, and men's/ladies' clubs, airports, parks, shopping malls, work places as well as their residences, and in the public areas of hospitals or outpatient clinics. A total of 6193 individuals were screened during MMM17. The mean age was 39.2 ± 13.1 years. After multiple imputation, 1867 (30.2%) had hypertension. Of individuals not receiving anti-hypertensive medication, 813 (15.8%) were hypertensive. Of 1054 individuals receiving anti-hypertensive medication, 427 (40.6%) had uncontrolled BP. MMM17 was a useful screening model as it makes BP measurement easily accessible. Eight hundred and thirteen (16%) possibly new hypertensives were uncovered and 427(40.6%) of those on treatment for hypertension were found to be uncontrolled. These results suggest that opportunistic screening can identify significant numbers with raised BP

A Comparative Evaluation of Aquaponic and Soil Systems on Yield and Antioxidant Levels in Basil, an Important Food Plant in Lamiaceae

Greenhouse and aquaponic productions of basil (Ocimum basilicum L.) are well established, but the comparison between these two methods is not studied in detail. A study was conducted to evaluate the performance of basil in both aquaponic and soil systems under greenhouse conditions. The plants were raised in aquaponic beds with ornamental fish and a set of plants was raised in soil pots under a greenhouse setup. The studied parameters were morphological, biochemical and antioxidant levels. In order to analyze the stress effects of an aquaponic system on plant defense mechanism, two different antioxidant enzymes (catalase and peroxidase) were analyzed. Water quality parameters were monitored during the entire study period. Based on the results, there was a significant increase in growth parameters in the aquaponic system when compared to the conventional greenhouse cultivation of basil plants. The photosynthetic parameters showed a decline in the aquaponic system, but the biochemical parameters showed an enhancement in the aquaponic system of growing basil plants. The antioxidants exhibited a significant increase in the aquaponic system, which suggests a water stress effect on the plants induced by the aquaponic growing system. From the results of this study, it can be concluded that the aquaponic system is the best suitable method for basil production in the UAE condition