Increasing Distribution Grid Hosting Capacity Through Wire And Non-Wire Solutions

Increased deployment of distributed generation (DG) can adversely impact the operational performance of distribution networks. This increment can potentially change network power flow and result in several operational issues such as reduced power quality, overvoltage, and ineffective protection. In order to quantify the degradation bounds of distribution operation due to increasing DG integration, the concept of hosting capacity is introduced. The aim of this thesis is to increase the DG hosting capacity in distribution network by proposing several wire and non-wire solutions. To this end, these solutions include network reconfiguration, reactive power control, and energy storage system deployment. The network reconfiguration can change the power flow in the system while the reactive power control can decrease the voltage rise and power loss in the system, which lead to increase in hosting capacity. The energy storage systems can be utilized to locally capture DG generation, which leads to an increase in the hosting capacity. This thesis introduces an optimization- based hosting capacity method developed based on a linear power flow model to optimally determine DGs hosting capacity. Numerical simulations on a radial distribution test system illustrate the effectiveness of the proposed solutions

Microwave imaging for security applications

Microwave imaging technologies have been widely researched in the biomedical field where they rely on the imaging of dielectric properties of tissues. Healthy and malignant tissue have different dielectric properties in the microwave frequency region, therefore, the dielectric properties of a human body’s tissues are generally different from other contraband materials. Consequently, dielectric data analysis techniques using microwave signals can be used to distinguish between different types of materials that could be hidden in the human body, such as explosives or drugs. Other concerns raised about these particular imaging systems were how to build them cost effectively, with less radiation emissions, and to overcome the disadvantages of X-ray imaging systems. The key challenge in security applications using microwave imaging is the image reconstruction methods adopted in order to gain a clear image of illuminated objects inside the human body or underneath clothing. This thesis will discuss in detail how microwave tomography scanning could overcome the challenge of imaging objects concealed in the human body, and prove the concept of imaging inside a human body using image reconstruction algorithms such as Radon transformation image reconstruction. Also, this thesis presents subspace based TR-MUSIC algorithms for point targets and extended targets. The algorithm is based on the collection of the dominant response matrix reflected by targets at the transducers in homogenous backgrounds, and uses the MUSIC function to image it. Lumerical FDTD solution is used to model the transducers and the objects to process its response matrix data in Matlab. Clear images of metal dielectric properties have been clearly detected. Security management understanding in airports is also discussed to use new scanning technologies such as microwave imaging in the future.The main contribution of this reseach is that microwave was proved to be able to image and detect illegal objects embedded or implanted inside human body

From Paris to Makkah: heat stress risks for Muslim pilgrims at 1.5 °C and 2 °C

The pilgrimages of Muslims to Makkah (Hajj and Umrah) is one of the largest religious gatherings in the world which draws millions of people from around 180 countries each year. Heat stress during summer has led to health impacts including morbidity and mortality in the past, which is likely to worsen due to global warming. Here we investigate the impacts of increasing heat stress during the peak summer months over Makkah at present levels of warming as well as under Paris Agreement's targets of 1.5 °C and 2 °C global mean temperature increase above pre-industrial levels. This is achieved by using multi member ensemble projections from the half a degree additional warming, prognosis and projected impacts project. We find a substantial increase in the exceedance probabilities of dangerous thresholds (wet-bulb temperature >24.6 °C) in 1.5 °C and 2 °C warmer worlds over the summer months. For the 3 hottest months, August, September and October, even thresholds of extremely dangerous (wet-bulb temperature >29.1 °C) health risks may be surpassed. An increase in exceedance probability of dangerous threshold is projected by two and three times in 1.5 °C and 2 °C warmer worlds respectively for May as compared to the reference climate. September shows the highest increase in the exceedance probability of extremely dangerous threshold which is increased to 4 and 13 times in 1.5 °C and 2 °C warmer worlds respectively. Based on the indicators of hazard, exposure and vulnerability, we carried out probabilistic risk analysis of life-threatening heat stroke over Makkah. A ten time increase in the heat stroke risk at higher wet-bulb temperatures for each month is projected in 2 °C warmer world. If warming was limited to 1.5 °C world, the risk would only increase by about five times, or half the risk of 2 °C. Our results indicate that substantial heat related risks during Hajj and Umrah happening over peak summer months, as it is the case for Hajj during this decade, will require substantial adaptation measures and would negatively affect the performance of the rite. Stringent mitigation actions to keep the global temperature to 1.5 °C can reduce the risks of heat related illnesses and thereby reduce the non-economic loss and damage related to one of the central pillars of a world religion.German Federal Ministry of Education and ResearchPeer Reviewe

Arabic Language Teachers’ Perceptions of a Standards-based Educational Reform in the UAE

Arabic language curriculum has been undergoing reforms across the Arab world to improve Arab students’ acquisition of their mother tongue. Reform initiatives including internationally funded projects have been aimed recently at reforming and modernizing the teaching and learning of the Arabic language. Many Arab countries have adopted a standards-based instruction model. However, there is a lack of vision regarding how this model can be successfully implemented at a national level. This article examines how standards-based curricular mandates have been translated into practice and how teachers perceive implementing the standards-based Arabic curriculum in public schools in Abu Dhabi. The study employs qualitative purposeful sampling and an exploratory methodology to collect experiences of Arabic teachers who implemented the curriculum from 2010 to 2017. The findings of the study uncover the main characteristics, successes, and challenges of the standards-based teaching model as perceived by teachers. The findings also display a consensus for implementing the standards-based Arabic curriculum among teachers. Additionally, the findings show that the educational model requires intense professional development that is rigorous, continuous and collaborative, mentorship and coaching in the classroom, integrated reformative efforts to change ineffective pedagogical practices and capacity building in the UAE

From Paris to Makkah: heat stress risks for Muslim pilgrims at 1.5 °C and 2 °C

The pilgrimages of Muslims to Makkah (Hajj and Umrah) is one of the largest religious gatherings in the world which draws millions of people from around 180 countries each year. Heat stress during summer has led to health impacts including morbidity and mortality in the past, which is likely to worsen due to global warming. Here we investigate the impacts of increasing heat stress during the peak summer months over Makkah at present levels of warming as well as under Paris Agreement's targets of 1.5 °C and 2 °C global mean temperature increase above pre-industrial levels. This is achieved by using multi member ensemble projections from the half a degree additional warming, prognosis and projected impacts project. We find a substantial increase in the exceedance probabilities of dangerous thresholds (wet-bulb temperature >24.6 °C) in 1.5 °C and 2 °C warmer worlds over the summer months. For the 3 hottest months, August, September and October, even thresholds of extremely dangerous (wet-bulb temperature >29.1 °C) health risks may be surpassed. An increase in exceedance probability of dangerous threshold is projected by two and three times in 1.5 °C and 2 °C warmer worlds respectively for May as compared to the reference climate. September shows the highest increase in the exceedance probability of extremely dangerous threshold which is increased to 4 and 13 times in 1.5 °C and 2 °C warmer worlds respectively. Based on the indicators of hazard, exposure and vulnerability, we carried out probabilistic risk analysis of life-threatening heat stroke over Makkah. A ten time increase in the heat stroke risk at higher wet-bulb temperatures for each month is projected in 2 °C warmer world. If warming was limited to 1.5 °C world, the risk would only increase by about five times, or half the risk of 2 °C. Our results indicate that substantial heat related risks during Hajj and Umrah happening over peak summer months, as it is the case for Hajj during this decade, will require substantial adaptation measures and would negatively affect the performance of the rite. Stringent mitigation actions to keep the global temperature to 1.5 °C can reduce the risks of heat related illnesses and thereby reduce the non-economic loss and damage related to one of the central pillars of a world religion

The Influence of the Madden–Julian Oscillation on the Wet Season Rainfall over Saudi Arabia

The influence of Madden–Julian oscillation (MJO) is examined on intraseasonal rainfall variability during the wet season (November–April) by using the real-time multivariate (RMM) MJO index, ERA5 reanalysis, and daily observed rainfall dataset from 26 stations in Saudi Arabia for the period 1985–2021. The MJO 8 phases are categorized into wet (phases 1, 2, 7 and 8) and dry (phases 3, 4, 5, and 6) based on the Saudi Arabian intraseasonal rainfall characteristics associated with MJO phases. It is observed that 41% (46%) of total (extreme) rainfall events occur during the MJO wet phases, while only 23% (18%) of such events occur during MJO dry phases. The intraseasonal variability signals are isolated from daily dataset by applying a 30- to 90-day period bandpass filter. The analyses are validated by constructing composites of daily filtered precipitation anomalies during MJO 8 phases. The physical mechanism indicates that the significant intraseasonal wetter conditions are linked with enhanced easterly and southeasterly moisture convergence over Saudi Arabia from the Arabian Sea. The atmospheric cyclonic circulation anomalies during the wet phases favor more moisture convergence and vertical moisture advection, which may lead to enhanced convection and rainfall. However, during the dry phases, anticyclonic circulation anomalies enhance moisture divergence and reduce vertical moisture advection and consequently suppress the convection and rainfall activity over Saudi Arabia. The analyses show that the intraseasonal rainfall variability over Saudi Arabia is significantly influenced by the MJO during the wet season. These findings have important implications for sub-seasonal rainfall forecasting in Saudi Arabia

Multidecadal Changes in the Relationship of Storm Frequency over Euro-Mediterranean Region and ENSO During Boreal Winter

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Contribution of Synoptic Transients to the Potential Predictability of PNA Circulation Anomalies: El Niño versus La Niña

Abstract The potential predictability (PP) of seasonal-mean 200-hPa geopotential height (Z200) anomalies in the Pacific–North American (PNA) region is examined for El Niño and La Niña separately by using 50 ensemble members of twentieth-century AGCM simulations. Observed sea surface temperature (SST) is prescribed for the period 1870–2009, and 14 El Niño and La Niña years after 1900 are selected for the present study. The domain-averaged value of PP for Z200 in the PNA region, as measured by the signal-to-noise ratio, for El Niño is about 60% larger than that of La Niña. Such a large PP is mainly due to a larger signal and partly to less noise during El Niño compared to that during La Niña . The transient eddy feedback to the PNA circulation anomalies is stronger during El Niño events (about 50%) than that during La Niña, and this difference in the transients contributes significantly to the different Z200 signals in the PNA region. The noise variance of the transients during El Niño is about 17% smaller than during La Niña, and thus transients play an important role in the reduction of Z200 noise during El Niño. Idealized experiments with the same spatial pattern but different signs of SST anomalies confirm the results mentioned above. Moreover, these experiments with several different amplitudes of positive and negative phases of tropical Pacific SST anomalies show that signals of Z200 and transients are proportional to precipitation anomalies in the tropical Pacific, and noises of Z200 for El Niño cases are somewhat smaller than the corresponding values of La Niña

ENSO relationship to summer rainfall variability and its potential predictability over Arabian Peninsula region

Rainfall Predictability: Droughts are Predictable in the Arabian Peninsula Drought conditions are particularly alarming for a water-scarce region like the Arabian Peninsula. Therefore, the prediction of regional rainfall is of utmost importance for the socio-economic sectors such as water and agricultural resources, so the policy makers can cope with drought situations. In the summer season, the Arabian Peninsula receives rainfall mostly in the southwestern region. El Niño Southern Oscillation (ENSO) strongly influences the southwestern peninsula rainfall and drives drought conditions in its warm phase. In this study it is shown that models are able to realize this potential, and Arabian Peninsula summer rainfall may be therefore predictable on a seasonal basis

Multidecadal Changes in the Relationship between ENSO and Wet-Season Precipitation in the Arabian Peninsula

Abstract Multidecadal variations in the relationship between El Niño–Southern Oscillation (ENSO) and the Arabian Peninsula rainfall are investigated using observed data for the last 60 years and various atmospheric general circulation model (AGCM) experiments. The wet season in the Arabian Peninsula from November to April was considered. The 6-month averaged Arabian rainfall was negatively correlated with ENSO for an earlier 30-yr period from 1950 to 1979 and positively correlated to ENSO for a more recent period from 1981 to 2010. The multidecadal variations can be attributed to the variations in Indian Ocean SST anomalies accompanied by ENSO. In the early 30-yr period, ENSO accompanied relatively large SST anomalies in the Indian Ocean, whereas in the recent 30-yr period it accompanied relatively small SST anomalies in the Indian Ocean. The atmospheric anomalies in the Arabian region during ENSO are combined responses to the Pacific and Indian Ocean SST anomalies, which offset each other during ENSO. The recent El Niño events accompanied negative 200-hPa geopotential height (GH) anomalies over the Arabian region, mainly forced by the Pacific SST anomalies, resulting in an increase of precipitation over the region. In contrast, in the early 30-yr period, Indian Ocean SST anomalies played a dominant role in the atmospheric responses over the Arabian region during ENSO, and the negative GH anomalies and more precipitation over the Arabian region were mainly forced by the negative SST anomalies over the Indian Ocean, which appeared during La Niña. These observed findings are confirmed by various AGCM experiments