2,629 research outputs found

    Hybrid PV-Wind, Micro-Grid Development Using Quasi-Z-Source Inverter Modeling and Control—Experimental Investigation

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    This research work deals with the modeling and control of a hybrid photovoltaic (PV)-Wind micro-grid using Quasi Z-source inverter (QZsi). This inverter has major benefits as it provides better buck/boost characteristics, can regulate the phase angle output, has less harmonic contents, does not require the filter and has high power performance characteristics over the conventional inverter. A single ended primary inductance converter (SEPIC) module used as DC-DC switched power apparatus is employed for maximum power point tracking (MPPT) functions which provide high voltage gain throughout the process. Moreover, a modified power ratio variable step (MPRVS) based perturb & observe (P&O) method has been proposed, as part of the PV MPPT action, which forces the operating point close to the maximum power point (MPP). The proposed controller effectively correlates with the hybrid PV, Wind and battery system and provides integration of distributed generation (DG) with loads under varying operating conditions. The proposed standalone micro grid system is applicable specifically in rural places. The dSPACE real-time hardware platform has been employed to test the proposed micro grid system under varying wind speed, solar irradiation, load cutting and removing conditions etc. The experimental results based on a real-time digital platform, under dynamic conditions, justify the performance of a hybrid PV-Wind micro-grid with Quasi Z-Source inverter topology

    Mathematical Modelling of the Relationship between Two Different Temperament Classifications: During the Covid-19 Pandemic

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    In medicine, it is well known that healthy individuals have different physical and mental characteristics. Ancient Indian medicine, Ayurveda and the Persian-Arabic traditional Unani medicine has two distinct approaches for the classification of human subjects according to their temperaments. The individual temperament is an important foundation for personalized medicine, which can help in the prevention and treatment of many diseases including COVID-19. This paper attempts to explore the relationship of the utmost important concepts of these systems called individual temperament named as Prakruti in Ayurveda and Mizaj in Unani practice using mathematical modelling. The results of mathematical modelling can be adopted expediently for the development of algorithms that can be applied in medical informatics. For this, a significant literature review has been carried out. Based on the previous researchers' reviews the essential parameters have been identified for making the relationship and hypothesis were framed. The mathematical modelling was adopted to propose the existence of the relationship between the parameters of such an ancient and rich medicine systems. The hypotheses are validated through the mathematic driven model. Doi: 10.28991/esj-2021-01258 Full Text: PD

    Micro Enterprise Financing in an Islamic Economic Framework: Bangladesh Perspective

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    Abstract. The paper studies the deficiency of the neo liberal policy agenda that aims totransform non-governmental organization (NGOs) engaged in poverty alleviationinto formal financial institutions seeking access to capital market and performingon a commercial basis. It propounds that poverty focused credit programs aimedat distributive equity are logically inconsistent with an ethically neutral liberal marketorder. In comparison, it is inferred in the paper that Islamic economic principles affirm the logical consistency and adequacy to reality of Islamicfinancial program and poverty focused credit programs. These programs, as indicated by the welfare banking ofIslamic Banks in Bangladesh, seek access to financialmarkets, which are characterized by the presence of Shariah instrument prohibiting interest and profiteering and promoting charity.Keywords. Micro finance, Micro business, Economic development.JEL. G21, N80, Q12

    Boundary spanning at the science–policy interface: the practitioners’ perspectives

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    Cultivating a more dynamic relationship between science and policy is essential for responding to complex social challenges such as sustainability. One approach to doing so is to “span the boundaries” between science and decision making and create a more comprehensive and inclusive knowledge exchange process. The exact definition and role of boundary spanning, however, can be nebulous. Indeed, boundary spanning often gets conflated and confused with other approaches to connecting science and policy, such as science communication, applied science, and advocacy, which can hinder progress in the field of boundary spanning. To help overcome this, in this perspective, we present the outcomes from a recent workshop of boundary-spanning practitioners gathered to (1) articulate a definition of what it means to work at this interface (“boundary spanning”) and the types of activities it encompasses; (2) present a value proposition of these efforts to build better relationships between science and policy; and (3) identify opportunities to more effectively mainstream boundary-spanning activities. Drawing on our collective experiences, we suggest that boundary spanning has the potential to increase the efficiency by which useful research is produced, foster the capacity to absorb new evidence and perspectives into sustainability decision-making, enhance research relevance for societal challenges, and open new policy windows. We provide examples from our work that illustrate this potential. By offering these propositions for the value of boundary spanning, we hope to encourage a more robust discussion of how to achieve evidence-informed decision-making for sustainability.Support for the workshop was provided by Margaret A. Cargill Philanthropies and The Pew Charitable Trusts. PFEA is supported by the U.K. Natural Environment Research Council (NE/N005457/1)

    Enhancing the potential exploitation of food waste: Extraction, purification, and characterization of renewable specialty chemicals from blackcurrants (Ribes nigrum L.)

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    Natural colorants were extracted from renewable botanical sources, specifically waste epicarp from the blackcurrant fruit pressing industry. A process was developed which used acidified water extraction followed by a solid-phase extraction (SPE) purification stage which allowed the production of an anthocyanin-rich extract in good yields (ca. 2% w/w based on dry weight of raw material). The components in the extracts were extensively characterized by HPLC, mass spectrometry, IR, NMR and UV-Vis spectroscopy. HPLC confirmed presence of four anthocyanins: delphinidin-3-O-rutinoside (45%), cyanidin-3-O-rutinoside (31%) and the corresponding glucosides at 16% and 8%, respectively. On sequential liquid-liquid aqueous-organic partitioning of the post-SPE sample, monomeric anthocyanins (54.7%) and polymeric anthocyanins (18%) were found in the aqueous layer with 3-O-rutinosides of myricetin (3.1%) and quercetin (3.2%), whilst isopropylacetate achieved selective extraction of caffeic acid (3%), p-coumaric acid (5%), and myricetin (2.5%) and quercetin (3.2%) aglycons. 3-O-Glucosides of myricetin (3.1%) and quercetin (2%), along with nigrumin-p-coumarate (1%) and nigrumin ferulate (0.5%) were selectively extracted from the remaining aqueous fraction using ethylacetate. This allowed for near total quantification of the blackcurrant extract composition

    Boundary spanning at the science–policy interface: the practitioners’ perspectives

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    Cultivating a more dynamic relationship between science and policy is essential for responding to complex social challenges such as sustainability. One approach to doing so is to “span the boundaries” between science and decision making and create a more comprehensive and inclusive knowledge exchange process. The exact definition and role of boundary spanning, however, can be nebulous. Indeed, boundary spanning often gets conflated and confused with other approaches to connecting science and policy, such as science communication, applied science, and advocacy, which can hinder progress in the field of boundary spanning. To help overcome this, in this perspective, we present the outcomes from a recent workshop of boundary-spanning practitioners gathered to (1) articulate a definition of what it means to work at this interface (“boundary spanning”) and the types of activities it encompasses; (2) present a value proposition of these efforts to build better relationships between science and policy; and (3) identify opportunities to more effectively mainstream boundary-spanning activities. Drawing on our collective experiences, we suggest that boundary spanning has the potential to increase the efficiency by which useful research is produced, foster the capacity to absorb new evidence and perspectives into sustainability decision-making, enhance research relevance for societal challenges, and open new policy windows. We provide examples from our work that illustrate this potential. By offering these propositions for the value of boundary spanning, we hope to encourage a more robust discussion of how to achieve evidence-informed decision-making for sustainability
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