181 research outputs found
Stress distribution of CFRP strengthened steel hollow sections under tension
No full textCarbon fibre reinforced polymer (CFRP) sheets have many outstanding properties such as high strength, high\ud
elastic modulus, light weight and good durability which are made them a suitable alternative for steel in\ud
strengthening work. This paper describe the ultimate load carrying capacity of steel hollow sections at effective\ud
bond length in terms of its cross sectional area and the stress distribution within bond region for different layers\ud
CFRP. It was found that depending on their size and orientation of uni- directional CFRP layers, the ultimate\ud
tensile load was different. Along with these tests, non linear finite element analysis was also performed to\ud
validate the ultimate load carrying capacity depending on their cross sections. The predicted ultimate loads\ud
from FE analysis are found very close to the laboratory test results. The validated model has been used to\ud
determine the stress distribution at bond joint for different orientation of CFRP. This research shows the effect\ud
of stress distribution and suitable wrapping layer to be used for the strengthening of steel hollow sections in\ud
tension
Protection of Inverter-based Distributed Generation with Series Dynamic Braking Resistor: A Variable Duty Control Approach
No full textFault current level in inverter based distributed generation (IBDG) integrated grid system increases manifold due to high level of IBDG penetration. Nevertheless, for having less detrimental effect of fault in the system fault current must be kept within specified limit as per new grid code. This paper proposes series dynamic braking resistor (SDBR) based protection scheme for IBDG with variable duty control strategy. SDBR is connected with the AC side of the IDBG to insert variable resistance during contingencies depending on the level of fault current. Current at the point of common coupling is employed to detect system disturbances. Feedback control strategy is developed for the control of DC link voltage such that the net power exchange with the DC capacitor is zero. Direct axis inner current control strategy is adopted to transfer IBDG power to grid. Symmetrical three phase to ground and unsymmetrical double line to ground faults are applied in the system to show the efficacy the proposed variable duty based SDBR control technique. The proposed variable duty based SDBR control scheme have been found as an effective solution to limit the fault current for IBDG system as evident from the simulation results.No Full Tex
Techno-Economic Feasibility Study of a 1.5 MW Grid-Connected Solar Power Plant in Bangladesh
No full textThis study addresses the pressing energy constraints in nations like Bangladesh by proposing the implementation of photovoltaic (PV) microgrids. Given concerns about environmental degradation, limited fossil fuel reserves, and volatile product costs, renewable energy sources are gaining momentum globally. Our research focuses on a grid-connected solar PV system model at Char Jazira, Lalpur, Natore, Rajshahi, Bangladesh. Through PVsyst 7.1 simulation software, we assess the performance ratio (PR) and system losses, revealing an annual solar energy potential of 3375 MWh at standard test condition (STC) efficiency. After considering losses, the system generates 2815.2 MWh annually, with 2774 MWh exported to the grid. We analyze an average PR of 78.63% and calculate a levelized cost of energy (LCOE) of 2.82 BDT/kWh [1 USD = 110 BDT]. The financial assessment indicates a cost-effective LCOE for the grid-connected PV system, with an annual gross income of 27,744 kBDT from selling energy to the grid and operating costs of 64,060.60 BDT/year. Remarkably, this initiative can prevent 37,647.82 tCO2 emissions over the project’s 25-year lifespan
Multidrug Resistance in Cancer: Understanding Molecular Mechanisms, Immunoprevention and Therapeutic Approaches
No full textCancer is one of the leading causes of death worldwide. Several treatments are available for cancer treatment, but many treatment methods are ineffective against multidrug-resistant cancer. Multidrug resistance (MDR) represents a major obstacle to effective therapeutic interventions against cancer. This review describes the known MDR mechanisms in cancer cells and discusses ongoing laboratory approaches and novel therapeutic strategies that aim to inhibit, circumvent, or reverse MDR development in various cancer types. In this review, we discuss both intrinsic and acquired drug resistance, in addition to highlighting hypoxia- and autophagy-mediated drug resistance mechanisms. Several factors, including individual genetic differences, such as mutations, altered epigenetics, enhanced drug efflux, cell death inhibition, and various other molecular and cellular mechanisms, are responsible for the development of resistance against anticancer agents. Drug resistance can also depend on cellular autophagic and hypoxic status. The expression of drug-resistant genes and the regulatory mechanisms that determine drug resistance are also discussed. Methods to circumvent MDR, including immunoprevention, the use of microparticles and nanomedicine might result in better strategies for fighting cancer
Measuring Households' Vulnerability to Idiosyncratic and Covariate Shocks – the case of Bangladesh
Get PDFThe paper examines the level and sources of vulnerability in rural Bangladesh using a household survey. We use a simple two-level random intercept model to estimate expected mean and variance in consumption as well as to decompose the variance into idiosyncratic and covariate components. Our results indicate that both idiosyncratic and covariate shocks have considerable impact on household's vulnerability and idiosyncratic shocks seem to have greater impact on household's consumption vulnerability than the covariate shocks. Furthermore, idiosyncratic shocks appear to have a relatively higher impact on relatively well endowed (i.e. in terms of human capital, land holdings, activity status etc.), well off households and covariate shocks seem to have a relatively higher impact on poorer, less educated, household's vulnerability. Our results also reveal that rural vulnerability in Bangladesh is mainly poverty induced rather than risk induced. Around 78 per cent all who are vulnerable is accounted for by low expected mean consumption and only 22 per cent of them are due to high consumption volatility. Overall vulnerability in rural areas is estimated to be 50 per cent. The categorization of poverty into transient and chronic poverty is even more insightful. The study finds that those without education or agricultural households are likely to be the most vulnerable. The geographical diversity of vulnerability is considerable. It is suggested that ex ante measures to prevent households from becoming poor as well as ex post measures to alleviate those already in poverty should be combined.Poverty, Vulnerability, Risks, Poverty dynamics, Bangladesh
A Field Course to Improve Student Performance and Scientific Interest in Applied Hydrology
Get PDFAdditional information on the Long Island Geologists may be found at: http://pbisotopes.ess.sunysb.edu/lig/. Information on the Long Island Association of Professional Geologists may be found at: www.liapg.org. | Long Island Geologists is a program of the Department of Geosciences at Stony Brook University. Each year, the activities include one or two field trips and, on a Saturday in April, a conference on the Geology of Long Island and Metropolitan New York. Teachers and professional geologists can receive in-service credit for participating in these events. The abstracts contained within this collection are digital representations or copies of papers presented over the years at various conferences. For additional information on a particular topic or paper, contact the original author(s)
A Field Course to Improve Student Performance and Scientific Interest in Applied Hydrology
No full textv. : ill.; 28 cm (original analog pub.)Long Island Geologists is a program of the Department of Geosciences at Stony Brook University.
Each year the activities include one or two field trips and on a Saturday in April a conference on the "Geology of Long Island and Metropolitan New York." Teachers and professional geologists can receive in-service credit for participating in these events. The abstracts contaiend within this collection are digital representations or copies of papers presented over the years at the various conferences that were held. For additional information on a particular topic or paper contact the original author(s).Archived web contentThe digital publication of the Long Island Geologists' Abstracts Collection was made possible through a collaboration between the LIG and the Special Collections and University Archvies, Stony Brook University Libraries.Additional information on the Long Island Geologists may be found at: http://pbisotopes.ess.sunysb.edu/lig/.
Information on the Long Island Association of Professional Geologists may be found at:
www.liapg.org
Solar and Wind Energy Integrated System Frequency Control: A Critical Review on Recent Developments
No full textA paradigm shift in power systems is observed due to the massive integration of renewable energy sources (RESs) as distributed generators. Mainly, solar photovoltaic (PV) panels and wind generators are extensively integrated with the modern power system to facilitate green efforts in the electrical energy sector. However, integrating these RESs destabilizes the frequency of the modern power system. Hitherto, the frequency control has not drawn sufficient attention due to the reduced inertia and complex control of power electronic converters associated with renewable energy conversion systems. Thus, this article provides a critical summary on the frequency control of solar PV and wind-integrated systems. The frequency control issues with advanced techniques, including inertia emulation, de-loading, and grid-forming, are summarized. Moreover, several cutting-edge devices in frequency control are outlined. The advantages and disadvantages of different approaches to control the frequency of high-level RESs integrated systems are well documented. The possible improvements of existing approaches are outlined. The key research areas are identified, and future research directions are mentioned so that cutting-edge technologies can be adopted, making the review article unique compared to the existing reviews. The article could be an excellent foundation and guidance for industry personnel, researchers, and academicians
Renewable energy integration with DC microgrids: Challenges and opportunities
No full textDC microgrids are currently experiencing a surge in attention and interest, emerging as a focal point in the global energy discourse due to their potential to enhance energy efficiency and seamlessly integrate renewable sources, including solar photovoltaic (PV). However, when large amounts of renewable energy sources are integrated, DC microgrids face difficulties with voltage regulation, energy management, inertia control, and uncertainty management. To address these difficulties, numerous approaches have been offered, such as droop control, centralized control, distributed control, virtual inertia control, and uncertainty management algorithms. Despite these efforts, a comprehensive overview that offers a panoramic understanding of the existing techniques and forthcoming trends in controlling renewable energy-integrated DC microgrids has been lacking. Thus, this article systematically reviews the challenges and opportunities arising from integrating renewable energy into DC microgrids. A comprehensive understanding of the challenges and potentials of renewable energy integration within DC microgrid systems is offered, thereby enriching the scholarly discourse in this field. The article provides a comprehensive evaluation of the inherent advantages and disadvantages of the existing methodologies while identifying specific areas that require additional investigation. The novelty of this work lies in its comprehensive review of challenges and opportunities in integrating renewable energy into DC microgrids, offering specific recommendations to enhance integration, and guiding future research in the field. Scholars, researchers, and professionals in related fields may all benefit greatly from this article.No Full Tex
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