The Efficiency Comparison of Hydro Turbines for Micro Power Plant from Free Vortex

In this research paper, the relationship between a crossflow turbine and propeller turbine size changes and the pond size in a free vortex power generation system was investigated. This relationship can be written in the form of a new mathematical equation using the principles of the response surface methodology (RSM) method. This study aimed to compare the efficiency of a crossflow turbine and propeller turbine to enhance a micro power plant from free vortex. The pond size in a micro power plant from free vortex was 1 m in diameter and 0.5 m in height with a 0.2 m outlet drain at the bottom. All turbines were tested at different water flowrates of 0.2, 0.3, 0.4, 0.5, and 0.6 m3/s to identify the rpm, water head, voltage, and electric current to access the waterpower, power output, and overall efficiency. At a 0.02 m3/s water flowrate, the crossflow turbine had greater overall efficiency than the propeller turbine, reaching 9.09% efficiency. From the comparison of the results of the two turbines used in the 0.5 m high cylinder-shaped generator pond, the turbine type, turbine size (height and diameter), number of blades, and water flowrate are key factors that affect the overall efficiency. The crossflow turbine can achieve greater efficiency than the propeller turbine in this generator system.

Mechanisms of Pond Expansion in a Rapidly Submerging Marsh

The development and expansion of ponds within otherwise vegetated coastal marshes is a primary driver of marsh loss throughout the world. Previous studies propose that large ponds expand through a wind wave-driven positive feedback, where pond edge erosion rates increase with pond size, whereas biochemical processes control the formation and expansion of smaller ponds. However, it remains unclear which mechanisms dominate at a given scale, and thus how, and how fast, ponds increase their size. Here, we use historical photographs and field measurements in a rapidly submerging microtidal marsh to quantify pond development and identify the processes involved. We find that as small ponds emerge on the marsh platform, they quickly coalesce and merge, increasing the number of larger ponds. Pond expansion rates are maximized for intermediate size ponds and decrease for larger ponds, where the contribution of wave-driven erosion is negligible. Vegetation biomass, soil shear strength, and porewater biogeochemical indices of marsh health are higher in marshes adjacent to stable ponds than in those adjacent to unstable ponds, suggesting that pond growth rates are negatively related to the health of the surrounding marsh. We find that the model of Vinent et al. (2021) correctly predicts measured pond growth rates and size distribution, which suggest the different mechanisms driving pond growth are a result of marsh drowning due to sea level rise (SLR) and can be estimated by simplified physical models. Finally, we show that all relevant processes increasing pond size can be summarized by an empirical power-law equation for pond growth which predicts the temporal change of the maximum pond size as a lower bound for the total pond area in the system. This gives a timescale for the growth of ponds by merging and thus the critical time window for interventions to prevent the irreversible pond expansion associated with large scale pond merging.

Determinants of profitability in catfish farming in Ilorin West Local Government Area of Kwara State, Nigeria

This study analysed the profitability of catfish farming in Ilorin west Local Government Area of Kwara State. Multistage sampling technique was used to collect data from 120 catfish farmers using structured questionnaire. Data collected were analysed using descriptive statistics, Gross margin analysis and linear regression. Result shows that more than half (54.17%) of the catfish farmers were males while majority (63.34%) of the farmers were within the age group 31- 50 years. The mean age and household size of farmers in the study area were 38 years and 5 persons respectively. Most of the catfish farmers (45.83%) utilized concrete pond type while average fish pond size was 205 square metres. Major source of finance for farmers is from their personal savings. The gross margin analysis shows that gross margin for the catfish farmers was ₦22,013,583.1 while the average gross margin was ₦183,446.52 perproduction cycle indicating that catfish farming is profitable. The result of the linear regression reveals that pond maintenance, transportation and feed cost are negative and have significant effects on income generated from catfish business while pond size and education is positive and significant at 5%. Since catfish business is a profitable venture, the study recommends that the Nigerian government should use this as a means to empower unemployed youths and rural households to reduce poverty level as well as dependence on fish importation in the country. Keywords: Catfish farmers, Profitability, Production, Gross margin, Personal saving.

Optimization of Pangasius Catfish Production in Pagersari Village, Tulungagung Regency

Pangasius catfish is freshwater fish for consumption that can be cultivated through fish farming. In order to produce optimal profits, Pangasius catfish farming must pay attention to the use of inputs in the form of seeds, feed and electricity. The purpose of this study was to analyze the optimization of Pangasius catfish production in Tondo Lestari fish cultivator group, Pagersari Village, Tulungagung Regency. Data collection techniques were in the form of interviews, observation and documentation. The data analysis used was linear programming using the POM-QM for Windows 5 software tool. The Pangasius catfish farming activities of the Tondo Lestari fish cultivator group have been optimal because they resulted in a low production difference between factual and optimal conditons of 3,05 kg or a profit of Rp. 10,502. . The optimal production of Pangasius catfish in a pond size of 200 m2 was 3,173.21 kg and the optimal production in a pond size of 300 m2 was 4,839.83 kg. Therefore, it can be concluded that Pokdakan Tondo Lestari can take advantage of additional feed and electricity input by reducing the use of seed input by 1.487 heads to increase profits.

Use of Fish Farming Practices by the Fish Farmers

The main purpose of the study was to determine the extent of use of fish farming practices by the fish farmers. This study was conducted at three unions named Hapania, Kirtipur, and Tilakpur of NaogaonSadarupazilla under Naogaon district. Ninety-two (92) fish farmers were randomly selected as sample from an updated list of 120 fish farmers. Data were collected by a pre-tested interview schedule during 20th September to 20th October 2020. Simple and direct questions with different appropriate scales were used to obtain information. Descriptive statistics and multiple regression analysis was used for the present study. Slightly above half (53.3 percent) of the fish farmers had medium use of fish farming practices, while 42.4 percent fish farmers had high use of fish farming practices, and only 4.3 percent fish farmers had low use of fish farming practices. Thus, overwhelming majority (95.7 percent) of the fish farmers had medium to high use of fish farming practices. Pond size, fish farming experience, cosmopoliteness, and extension contacts of the respondents had significant positive contribution with their use of fish farming practices. Coefficients of other selected variables namely age, education, family size, annual income, and knowledge on fish farming didn’t have any significant contribution with their use of fish farming practices. ‘Lack of government support’ emerged as the 1st ranked problem as per opinion given by the fish farmers (77.17 percent). The least problem as per opinion given by the fish farmers was ‘High labor cost’. Res. Agric., Livest. Fish.7(3): 565-576, December 2020

Macrobiont: Cradle for the Origin of Life and Creation of a Biosphere

Although the cellular microorganism is the fundamental unit of biology, the origin of life (OoL) itself is unlikely to have occurred in a microscale environment. The macrobiont (MB) is the macro-scale setting where life originated. Guided by the methodologies of Systems Analysis, we focus on subaerial ponds of scale 3 to 300 m diameter. Within such ponds, there can be substantial heterogeneity, on the vertical, horizontal, and temporal scales, which enable multi-pot prebiotic chemical evolution. Pond size-sensitivities for several figures of merit are mathematically formulated, leading to the expectation that the optimum pond size for the OoL is intermediate, but biased toward smaller sizes. Sensitivities include relative access to nutrients, energy sources, and catalysts, as sourced from geological, atmospheric, hydrospheric, and astronomical contributors. Foreshores, especially with mudcracks, are identified as a favorable component for the success of the macrobiont. To bridge the gap between inanimate matter and a planetary-scale biosphere, five stages of evolution within the macrobiont are hypothesized: prebiotic chemistry → molecular replicator → protocell → macrobiont cell → colonizer cell. Comparison of ponds with other macrobionts, including hydrothermal and meteorite settings, allows a conclusion that more than one possible macrobiont locale could enable an OoL.

Present Status of Aquaculture and Socio-Economic Condition of Fish Farmers in a Rural Setting in Bangladesh

The socio-economic condition of fish farmers was assessed in the HabiganjSadarupazila, Habiganj, Bangladesh to determine the constraints and vulnerability of thecommunity in term of aquaculture. Data from 30 fish farmers were collected duringJanuary to May 2019. Among surveyed farmers, most of the pond size (37.61%)ranged between 0.02 ha to 0.06 ha and 63.33% of ponds under single ownership. Mostof the farmers were interested to stock rohu, catla, mrigal along with other species andaverage stocking density was found to be 16236 fry/ha. All farmers provided feeds forthe cultured species and 73.33% farmers have taken measures against diseaseoutbreak. The highest production was estimated as 6.19 MT/ha/year and lowestproduction was 0.54 MT/ha/year. Highest income of farmer was reported as 5,00,000Tk/ha/year and the lowest as 74534 Tk/ha/year. Highest 34.38% farmers in the studyarea reported high cost of feed is the most important constraint. The study indicatedthat majority of fish farmers (33.33%) were in age structure of 31-40 years. Similar tothe religious profile of the population, Muslims (93.33%) dominated the ownership.Among all the farmers, 40% received primary level education. The study revealed that60% of farmers lived in joint families with tin shed house (43.33%). All farmers hadelectricity in their house and at least one mobile phone. Among the farmers 53.33%have good sanitary facility and 83.33% farmers had own tubewell for drinking waterfacility. 50% farmers received health service from village doctor and 33.33% farmersreceived technical training on fish farming. Res. Agric., Livest. Fish.7(2): 329-339, August 2020

Hydrological characterization of livestock watering ponds in semi-arid rangelands of the southwestern Iberian Peninsula

<p>Watering ponds are the main source of drinking water supply for livestock in the rangelands of the SW Iberian Peninsula. Most of these ponds consist of small earth dams which collect surface runoff from intermittent streams, with pond sizes rarely exceeding 1 ha. Understanding the hydrological functioning of this type of infrastructures is crucial for an efficient water management in extensive livestock farms, especially in semi-arid areas, where water resources are often scarce.</p><p>In this line, we have analysed the temporal patterns of water availability in a sample of representative livestock watering ponds in the SW Iberian Peninsula, being the objectives (1) to determine the influence of temporal rainfall variability on water availability in the ponds; (2) to examine the influence of factors such as pond size and catchment area on the effectiveness of the ponds, understood as their capacity to keep water during dry periods; and (3) to suggest minimum values for those factors, which can serve as a guide for the design of watering ponds in comparable rangeland areas. The applied methodology was primarily based on the analysis of aerial photographs and rainfall data available from public sources, requiring only few field measurements, and could therefore be used in areas with data scarcity.</p><p>High correlation coefficients were obtained between the water availability observed in the ponds and the antecedent rainfall at several time scales, evidencing the principal role of precipitation in the hydrological dynamics of these infrastructures in the study area. The accumulation periods (AP) of antecedent rainfall that best explained the hydrological response of the ponds depended largely on pond size. In those ponds whose maximum flooded area (A<sub>max</sub>) was less than 2000 m<sup>2</sup>, water availability in the ponds was greatly influenced by AP between 2 and 5 months, while for the ponds larger than 2000 m<sup>2</sup>, the best correlations were obtained for AP greater than 6 months. These results highlight the key role of the size of the ponds in their effectiveness. Thus, since the dry season usually lasts in the study area for 3-4 months, the large ponds (A<sub>max</sub> > 2000 m<sup>2</sup>) could remain operational throughout the summer, if it rains enough during the wet season and if their watersheds are large enough to allow a sufficiently high pond water level to be reached at the end of the wet season. In relation to the latter, the analyses carried out led us to suggest, for the study area, a minimum value of the catchment-area/pond-capacity ratio around 100 m<sup>-1</sup>.</p><p>Moreover, the analysis of the water availability observed in the ponds under drought conditions (i.e., with an antecedent rainfall substantially lower than normal for the corresponding time of year) revealed a high vulnerability to droughts in most of the ponds, which limits their use as the sole source of water supply in many farms.</p>

Melt pond distribution and geometry in high Arctic sea ice derived from aerial investigations

ABSTRACTAerial photography was conducted in the high Arctic Ocean during a Chinese research expedition in summer 2010. By partitioning the images into three distinct surface categories (sea ice/snow, water and melt ponds), the areal fraction of each category, ice concentration and the size and geometry of individual melt ponds, are determined with high-spatial resolution. The ice concentration and melt pond coverage have large spatial deviations between flights and even between images from the marginal ice zone to the pack ice zone in the central Arctic. Ice concentration and pond coverage over high Arctic (from 84°N to north) was ~75% and ~6.8%, respectively, providing ‘ground truth’ for the unusual transpolar reduction strip of ice indicated concurrently by AMSR-E data and for the regions (north of 88°N) where no passive microwave sensors can cover. Melt pond size and shape distributions are examined in terms of pond area (S), perimeter (P), mean caliper dimension (MCD) (L), roundness (R), convex degree (C), the ratio of P/S and fractal dimension (D). Power-law relationships are developed between pond size and number. Some general trends in geometric metrics are identified as a function of pond area including R, C, P/S and D. The scale separation of pond complexity is demonstrated by analyzing area-perimeter data. The results will potentially help the modelling of melt pond evolution and the determination of heterogeneity of under-ice transmitted light fields.