The performance of a photovoltaic (PV) array is affected by temperature, solar insolation, shading, and array configuration. Often, the PV arrays get shadowed, completely or partially, by the passing ...clouds, neighboring buildings and towers, trees, and utility and telephone poles. The situation is of particular interest in case of large PV installations such as those used in distributed power generation schemes. Under partially shaded conditions, the PV characteristics get more complex with multiple peaks. Yet, it is very important to understand and predict them in order to extract the maximum possible power. This paper presents a MATLAB-based modeling and simulation scheme suitable for studying the I-V and P-V characteristics of a PV array under a nonuniform insolation due to partial shading. It can also be used for developing and evaluating new maximum power point tracking techniques, especially for partially shaded conditions. The proposed models conveniently interface with the models of power electronic converters, which is a very useful feature. It can also be used as a tool to study the effects of shading patterns on PV panels having different configurations. It is observed that, for a given number of PV modules, the array configuration (how many modules in series and how many in parallel) significantly affects the maximum available power under partially shaded conditions. This is another aspect to which the developed tool can be applied. The model has been experimentally validated and the usefulness of this research is highlighted with the help of several illustrations. The MATLAB code of the developed model is freely available for download.
In a dc microgrid, several batteries with their converters are controlled to share the bus deficient/excessive power among themselves. A battery management system is required to improve the ...reliability and appropriate power-sharing. A novel control strategy is proposed in this article that ensures power sharing among the various batteries in accordance with their power rating and state of charge (SOC). In the proposed scheme, a common time reference ( T ref ) is generated using the conventional dc-bus voltage control loop and SOC information of the batteries with the help of communication. An attractive feature of the proposed scheme is that it does not depend on output current of the converters. Voltage regulation is also maintained within limits in case of wide deviation in the converter output voltage at interfacing point by monitoring and using corrective measures. A low-speed communication is sufficient to convey the reference time to the controllers of the batteries. The batteries are charged or discharged in the same time interval irrespective of the initial SOC, which significantly increases their life and performance. The proposed system is more reliable as it is tolerant to various fault scenarios. All the analytical, simulation and experimental results are presented.
Resting-state functional magnetic resonance imaging (rsfMRI) is a novel approach that has the potential to examine abnormalities in the default mode network (DMN) component. Two different approaches ...were used in the present study to characterize the functional connectivities of various DMN components in 16 non-medicated ADHD and a similar number of TD (typically developing) children. rsfMRI data were analysed using independent component analysis (ICA) and region-of-interest (ROI) seed to voxel correlation analysis. ICA results indicated a strong coherence of the left dorsal anterior cingular cortex (dACC) with the DMN components in children with ADHD. In addition, seed-to-voxel functional connectivity analysis using the left dorsal anterior cingulate as a seed region suggested higher temporal coherence with other neural networks upon comparison with TD children. These results imply children with ADHD exhibit a higher dispersed resting state connectivity pattern in DMN and other networks.
Abstract Purpose Neuroimaging studies provide vital information related to the neurobiology of ADHD, but there still exists a wide gap in relevant information. The present study aimed to elucidate ...the neuroanatomical alteration in Attention deficit hyperactivity disorder (ADHD) children/adolescents. Methods Voxel-based cortical thickness (VBCT) and voxel-based morphometry (VBM) was performed to examine neuroanatomic distinctions in 18 children/adolescents aged 7.5–13 years diagnosed with DSM-IV TR as ADHD (non-medicated). They were compared with 18 healthy matched controls. Results VBCT findings in ADHD children/adolescents revealed reduced cortical thickness in the left superior frontal, left orbito-frontal and left dorsal anterior cingulate cortex. VBM findings confirmed decreased gray matter volume in the left orbito frontal, left middle frontal/dorsolateral prefrontal, left middle temporal and left cerebellum in comparison to control group. A decrease in white matter volume was also observed in the left inferior frontal and left calcarine of ADHD children/adolescents. Conclusion Results reflect possible abnormal neuroanatomical development patterns in ADHD children.
To attain automation across different applications, industries are beginning to leverage advancements in wireless communication technologies. A ”one-size-fits-all” solution cannot be applied since ...wireless technologies are selected according to application needs, quality of service requirements, and economic restrictions. To balance the trade-off between technical and economic requirements, a multi-band heterogeneous wireless network architecture is presented and discussed in this paper. Wireless local area network (WLAN) and distributed antenna system (DAS) with Long Term Evolution (LTE) are considered as the backbone for the multi-band heterogeneous network into which other wireless technologies can be integrated. The technical and economic feasibility of the network are evaluated through a techno-economic analysis (TEA). The economic feasibility of the proposed network is measured in terms of net present value while the technical feasibility is measured in terms of network throughput and latency. Finally, network performance for DAS with LTE and WLAN are verified using an NS3 simulator for machine-to-machine, real-time video, and high-definition video data transmissions. The TEA analysis showed that the number of DAS units required to achieve technical feasibility is less than WLAN units, but the overall cost of DAS units are higher compared to WLAN units, even without taking into consideration industrial, scientific, and medical band technologies.
Because of the growing concerns regarding climate change and energy sustainability, a transition toward a modern energy sector that reduces environmental effects while promoting social and economic ...growth has gained traction in recent years. Sustainable energy solutions, which include renewable and low-carbon sources such as nuclear energy and natural gas, could minimize emissions of greenhouse gases, enhance air and water quality, and encourage energy independence. Yet, the shift to a sustainable energy industry is fraught with difficulties, including governmental and regulatory obstacles, technological and economic limits, and societal acceptability hurdles. Addressing these issues would necessitate the development of long-term, durable, and cost-effective energy systems containing nuclear energy and associated with the generation of both electricity and other by-products required by industry. Integrated energy systems (IES) are a novel way to maximize the use of various energy resources and technologies in order to deliver dependable, efficient, and sustainable energy services. IES entail the integration of various energy systems, such as electricity, heating, cooling, and transportation, in respect to energy sustainability and a system’s resilience and flexibility. Their development and implementation require the cooperation of several parties, including energy providers and policymakers. This study provides a state-of-the-art literature review of the most creative nuclear-driven hybrid energy system applications and methodologies, from which the research challenges and prospects for effective IES implementation emerge.
Despite its many desirable features, a bipolar dc microgrids (BDCMG) requires a large number of conventional dc-dc converters to feed power to its two poles. Besides, the BDCMG is also prone to ...voltage imbalance due to unequal load distribution across its two poles. To overcome these issues, this article presents a novel nonisolated boost-SEPIC type interleaved (BSTI) dc-dc converter topology that enables power from a single source to be fed into the two poles of the BDCMG, thereby, reducing the total number of converters in the system. The proposed converter can support bidirectional operation with synchronous rectification. Furthermore, the input current ripple is low due to interleaved operation. A novel method to mitigate the voltage imbalance in a BDCMG using BSTI converter is also proposed. In the proposed method, the neutral line-current in the BDCMG is reduced, thereby, decreasing the overall line-losses. The BSTI converter operates as a dc compensator (like STATCOM in ac systems), where, apart from the converter losses it does not supply or consume any active-power. Hence, no active source (e.g., battery) is required for mitigating the voltage imbalance. Detailed theoretical analysis and experimental results are presented to validate the efficacy and feasibility of the proposed schemes.
The capacity of aquifers to store water and the stability of infrastructure can each be adversely influenced by variations in groundwater levels and subsequent land subsidence. Along the south bank ...of the River Thames, the Battersea neighbourhood of London is renovating a vast 42-acre (over 8 million sq ft) former industrial brownfield site to become host to a community of homes, shops, bars, restaurants, cafes, offices, and over 19 acres of public space. For this renovation, between 2016 and 2020, a significant number of bearing piles and secant wall piles, with diameters ranging from 450 mm to 2000 mm and depths of up to 60 m, were erected inside the Battersea Power Station. Additionally, there was considerable groundwater removal that caused the water level to drop by 2.55 ± 0.4 m/year between 2016 and 2020, as shown by Environment Agency data. The study reported here used Sentinel-1 C-band radar images and the persistent scatterer interferometric synthetic aperture radar (PSInSAR) methodology to analyse the associated land movement for Battersea, London, during this period. The average land subsidence was found to occur at the rate of −6.8 ± 1.6 mm/year, which was attributed to large groundwater withdrawals and underground pile construction for the renovation work. Thus, this study underscores the critical interdependence between civil engineering construction, groundwater management, and land subsidence. It emphasises the need for holistic planning and sustainable development practices to mitigate the adverse effects of construction on groundwater resources and land stability. By considering the Sustainable Development Goals (SDGs) outlined by the United Nations, particularly Goal 11 (Sustainable Cities and Communities) and Goal 6 (Clean Water and Sanitation), city planners and stakeholders can proactively address these interrelated challenges.
Renewable sources like solar photovoltaic (PV) and fuel cell stack are preferred to be operated at low voltages. For applications such as grid-tied systems, this necessitates high voltage boosting ...resulting in efficiency reduction. To handle this issue, this paper proposes a novel high voltage gain, high-efficiency dc-dc converter based on coupled inductor, intermediate capacitor, and leakage energy recovery scheme. The input energy acquired from the source is first stored in the magnetic field of coupled inductor and intermediate capacitor in a lossless manner. In subsequent stages, it is passed on to the output section for load consumption. A passive clamp network around the primary inductor ensures the recovery of energy trapped in the leakage inductance, leading to drastic improvement in the voltage gain and efficiency of the system. Exorbitant duty cycle values are not required for high voltage gain, which prevents problems such as diode reverse recovery. Presence of a passive clamp network causes reduced voltage stress on the switch. This enables the use of low voltage rating switch (with low "on-state" resistance), improving the overall efficiency of the system. Analytical details of the proposed converter and its hardware results are included.
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