130 research outputs found
Inverter Power Stage Connected with PV-Grid
Abstract This paper focuses on the design of the inverter power stage connected with PV-grid which supports the contrived PV system. The increased number of grid connected photovoltaic (PV) inverters gave rise to problems concerning the stability and safety of the utility grid, as well as power quality issues. The proposed systems can overcome these issues and improve standard regulation methods for gird connected PV inverter. The maximum available voltage in the PV string is tracked by the power stage which has been planned and designed in such a way. The tracked voltage is boosted then. The important components to voltage source inverter (VSI) are boost inductor and input capacitor which are calculated. To get a clear sinusoidal output phase voltage of 230 V from a DC capacitance bus projected to deal with 400 V, the important inverter stage parameters have been planned and modeled in Mat lab. Each block stage of the converter is easily understandable by the Simlink of the dual stage DC-AC converter explanation. The control schemes which have been proposed would compromise with the inverter power stage which forms the neat grid system. The existing renewable energy sources in the laboratory are integrated by the proposed control
Fishery and Exploitation of Malabar Grouper, Epinephelus malabaricus (Bloch & Schneider 1801) from Andaman Islands
The fishery and population dynamics of groupers from Andaman Islands were studied from Jan 2010 to Dec
2011 with a special emphasis on Malabar grouper, Epinephelus malabaricus (Bloch & Schneider 1801). The average
annual catch of Malabar grouper was 1,296 tonnes contributing to 21.6% of annual grouper landings. Length-weight
relationship of Malabar grouper showed that growth was allometric (b=2.96) and relative condition factor (Kn) was 1
and the growth parameters viz., L∞, K and t0 were 124.60 cm, 0.80 and -0.05 respectively. The recruitment pattern was
unimodal with one major peak during April to July throughout the study period. The natural mortality (M), fishing
mortality (F) and total mortality (Z) were 1.05, 1.48 and 2.53 respectively and exploitation rate (E) was 0.58. The M/K
ratio (1.31) was found to be well within the normal range of 1to 2.5. Catch per unit effort varied from 4 to16.5 kg.h-1.
The maximum sustainable yield (MSY) was 1,107 tonnes which was lower than the average annual catch (1,296 tonnes),
indicating over exploitation. The current study calls for further research in identifying the grouper fishing and spawning
aggregation grounds and introduce measures for reducing fishing efforts with input and output controls to sustain the
Malabar grouper fishery in Andaman waters
Impact evaluation of marine fisheries interventions among Tribal Fisher Commune of Car Nicobar Island, India
Fisheries and tourism are two important sectors that provide
livelihood and employment in the tropical Islands. Andaman and
Nicobar group of Islands is a biodiversity hotspot in the Bay of
Bengal inhabited by settler population along with indigenous tribal
communities. The Nicobar tribal community is one among occupying
the Nicobar group of Islands in the majority and are quite socialized
tribal communities of the Islands. Agriculture, animal husbandry and
fisheries are the major sectors that contribute to the livelihood and
nutritional security of the Nicobar tribes. Traditional fishing activities
have been a part of their culture over the years however, tribal
youths were reluctant in taking up fishing as a profession considering
the changing scenario and alternative employment options. To
reinstate fisheries as a profession and to improve their livelihood and
employment opportunities, interventions were carried out in Car
Nicobar Island. The interventions were mainly aimed towards
increasing fish catches, to expand their fishing grounds and to
sensitize safe fishing and navigation practices. Fishing inputs such as
modern fishing boats, GPS and outboard engines were provided as
inputs to tribal fishers based on the outcome of an expert
consultation meeting. Structured questionnaires were prepared to
analyze the impact of the interventions. The results indicated that the
interventions led to a significant improvement (p <0.001) in the
expansion of their fishing grounds (3.47 ± 0.2 km), reduced time
spent to reach the fishing grounds (2.3 ± 0.25 hour) and increased
catch per unit effort (7.93 ± 1.23 kg/boat). This study shows that
the targeted interventions coupled with awareness and sensitization
programmes could make fishing activities profitable, attractive and
can motivate the unemployed youths to opt for fishing as a
profession
Efficacy of different modes in disseminating Potential Fishing Zone (PFZ) forecasts - a case study from Andaman and Nicobar Islands
Potential Fishing Zone forecasts based on Indian Remote Sensing satellite P4 Ocean Colour Monitor derived chlorophyll
concentration and National Oceanographic Aerospace Administration-Advanced Very High Resolution Radiometer derived
sea surface temperature were disseminated through different modes viz., Digital display boards, e-mail, telephoning/text
messaging, radio, community networking and distribution of print-outs in person to the targeted fishermen and the efficacy
was tested. Profound reach of technology dissemination was observed in telephoning/text messaging with an average
of 72 users per forecast. Printouts of PFZ maps were distributed to an average of 35 fishermen/boat-masters in person.
Digital Display Boards were viewed by 30 fishermen per forecast. E-mail message containing PFZ forecasts were sent
to regional fisheries sub-stations of remote islands and it was inferred that an average of 15 fishermen per forecasts were
benefitted. Further, PFZ messages were transmitted through All India Radio and Agromet Field Unit for extensive reach all
along the inhabited islands. Since the validity period of PFZ forecasts is limited to 2-3 days, near real-time dissemination
through telephoning/text messaging was found as an optimal tool for efficient utilisation. Field level constraints in different
dissemination modes are illustrated in the paper
Impact of Coastal Pollution on Microbial and Mineral Profile of Edible Oyster (Crassostrea rivularis) in the Coastal Waters of Andaman
The impact of coastal pollution was studied
using edible oysters, Crassostrea rivularis as an indicator
at two sites viz., North Wandoor (NW) and Phoenix Jetty
(PJ) in Port Blair, Andaman. The hydrographic parameters
showed that nitrite, nitrate and phosphate concentration
were less and dissolved oxygen were more at NW compared
to PJ. The oysters were collected from the study sites
and biochemical, microbial, mineral profiles and ATPase
activities were estimated. ATPase activity was inhibited in
the gill tissue of oysters (p\0.05) of PJ sample. Total
microbial load in the water and oyster, and coliform bacteria
(MPN) in the water were significantly (p\0.05)
higher at PJ compared to the NW. There was no significant
difference (p[0.05) in the mineral profile of water collected
from both the sites. However, calcium and magnesium
were more in the oysters collected from NW
(p\0.05), and Cu, Zn and Cd were more in PJ samples
(p\0.05)
Fisheries governance in the tropical archipelago of Andaman and Nicobar – opinions and strategies for sustainable management
Globally, marine fisheries sector provides livelihood, food security and employment to the fishers engaged in subsistence, artisanal and industrial fishing activities. The dependency on marine fish supplies keeps rising globally leading to intense competition, fishery conflicts and unsustainable fishing practices which threatens the sustainability and leading to the depletion of marine fishery resources. Andaman and Nicobar Islands (ANI) in India is a tropical archipelago cited as an example where marine fishery resources were considered to be highly underutilized vis-a-vis the harvestable potential
Hollow-structured NiCoP nanorods as high-performance electrodes for asymmetric supercapacitors
One-dimensional hollow-structured NiCoP nanorods are synthesized via Kirkendall effect resulting from different diffusion rates of Ni and Co ions at 350 °C, using NaH2PO2 as a phosphorization agent. Various techniques were used to study the formation mechanism of hollow NiCoP nanorods which structure and crystallinity could be effectively tuned by adjusting phosphorization time. Capacitance of NiCoP reaches 273.4 μAh cm−2 at a current density of 30 mA cm−2 with a rate retention of 85.6%. Specific capacitance of an asymmetric supercapacitor cell (ASC) where NiCoP sample was used together with activated carbon reached 264.6 μAh cm−2 at 2 mA cm−2 and decreased to 213.2 μAh cm−2 with current density rising to 30 mA cm−2. The ASC possesses quite high energy- and power densities, compared to previously reported results, which demonstrates applicability of hollow NiCoP nanorods for electrochemical energy storage
Recent advances in hydrothermal carbonisation:from tailored carbon materials and biochemicals to applications and bioenergy
Introduced in the literature in 1913 by Bergius, who at the time was studying biomass coalification, hydrothermal carbonisation, as many other technologies based on renewables, was forgotten during the "industrial revolution". It was rediscovered back in 2005, on the one hand, to follow the trend set by Bergius of biomass to coal conversion for decentralised energy generation, and on the other hand as a novel green method to prepare advanced carbon materials and chemicals from biomass in water, at mild temperature, for energy storage and conversion and environmental protection. In this review, we will present an overview on the latest trends in hydrothermal carbonisation including biomass to bioenergy conversion, upgrading of hydrothermal carbons to fuels over heterogeneous catalysts, advanced carbon materials and their applications in batteries, electrocatalysis and heterogeneous catalysis and finally an analysis of the chemicals in the liquid phase as well as a new family of fluorescent nanomaterials formed at the interface between the liquid and solid phases, known as hydrothermal carbon nanodots
Study on Fatigue Life of Heat-treated Aluminium alloy coated with Castor oil.
This paper involves the study of fatigue life of coated aluminium alloy Al 7075-T651 that is heat-treated under 100oC soaked in castor oil for three days. The specimen after heat treatment is subjected to fatigue test using rotary bending machine for number of cycles to fail under cyclic load of 15kgf, 25Kgf, and 50kgf.The life of the specimen is found and compared with uncoated specimen and improved life in number of cycle is noticed. The crack propagation and its type is analysed using scanning electron microscope for knowing the point of fracture and its initiation to failure
Study on Fatigue Life of Heat-treated Aluminium alloy coated with Castor oil.
This paper involves the study of fatigue life of coated aluminium alloy Al 7075-T651 that is heat-treated under 100oC soaked in castor oil for three days. The specimen after heat treatment is subjected to fatigue test using rotary bending machine for number of cycles to fail under cyclic load of 15kgf, 25Kgf, and 50kgf.The life of the specimen is found and compared with uncoated specimen and improved life in number of cycle is noticed. The crack propagation and its type is analysed using scanning electron microscope for knowing the point of fracture and its initiation to failure
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