NOPR Collection:

Combination of Beidou and GPS observations to establish regional Ionospheric map

2020-07-01T00:00:00Z

Title: Combination of Beidou and GPS observations to establish regional Ionospheric map Authors: Wang, X Z; Ke, F Y Abstract: This paper uses dual-model observations of the 118 stations from October 11^th to November 27^th, 2016 to establish the quasi real time Beidou Regional Ionospheric Map (RIMC), GPS Regional Ionospheric Map (RIMG) and the combined Regional Ionospheric Map (RIMM). The precise weights of each Beidou and GPS observations are determined by using the Helmert variance component estimation method. Then the DCBs of GPS satellites are compared with that published by CODE. The grid points of the areas where the IPPs covers are selected to further analyze the accuracy of the RIMM by comparing with the RIMC, RIMG and CODE GIM of DoY 287-332, 2016. The experimental results show that the accuracy of the RIMM improves about 0.3 TECU after adding the GPS observations. Page(s): 1125-1131

An improved PV system with auto-protection to inject active power into the power grid of marine ships

2020-07-01T00:00:00Z

Title: An improved PV system with auto-protection to inject active power into the power grid of marine ships Authors: Dhiman, S; Nijhawan, P Abstract: Photovoltaic (PV) system is turning into an ideal secondary power source for marine ships because of the ability to trap nature’s green energy. In this paper, a ship’s power grid connected PV system is proposed. The proposed system will help to inject the active power into the ship’s electric power grid together with a protection scheme, which will prevent the PV system and ship’s power grid from different faulty conditions. The proposed system has facility to track the maximum power point (MPP) of PV array by means of hybrid MPPT method and flyback DC-DC converter. Space vector pulse width modulation (SVPWM) technique controlled 3-phase full-bridge VSI is used to convert DC bus voltage into useful 3-phase AC output in order to feed the local load and transmit excess AC power into the ship’s bus. Furthermore, an isolation transformer is used to provide galvanic isolation amid PV system and ship’s power grid. Page(s): 1132-1142

Wave attenuation by coastal vegetation – An Empirical study on synthetic models

2020-07-01T00:00:00Z

Title: Wave attenuation by coastal vegetation – An Empirical study on synthetic models Authors: Hemavathi, S; Manjula, R Abstract: The interaction between wave and submerged vegetation is the primary cause of wave-induced attenuation. Studies on wave vegetation interactions mostly considered aquatic monotypic plant meadows and limited work have been reported on heterospecific plant meadows, common in tropical shores of southern India. An attempt was made to understand the heterospecific vegetation meadow-wave interactions through a two-level, four factors, full factorial experimental design-based laboratory flume study under controlled conditions. Simulated vegetation mimics were used as a simplified representation of heterospecific seagrass species, Halophila spinulosa, Halophila ovalis to develop a linear empirical model. Four input variables viz., water depth (h), wave period (T), plant density (N) and bed roughness factor (f), were considered for the study with the wave attenuation (E %) as a response. The developed model was tested for adequacy by using the analysis of variance (ANOVA) technique. Main and interaction effects of the input variables were analyzed, compared, and validated. The results show that all the four input variables are statistically significant with the T has the highest significant individual effect on wave attenuation followed by f, h, and N. Evidential two-way interaction effects, mainly between h with the rest of the parameters were also observed. Page(s): 1143-1152

Biochemical composition of selected seaweeds from intertidal shallow waters of Southern Red Sea, Eritrea

2020-07-01T00:00:00Z

Title: Biochemical composition of selected seaweeds from intertidal shallow waters of Southern Red Sea, Eritrea Authors: Kasimala, M; Mogos, G G; Negasi, K T; Bereket, G A; Abdu, M M; Melake, H S Abstract: Seaweeds are marine plants also known as sea vegetables, used as an alternative food source with high nutritional value. Consumption of seaweeds in East Asian countries like China, Thailand and Japan had begun since ancient times. In some countries, seaweeds are consumed as raw vegetables, in the form of salad and as an additive in manufacturing of various food products. The biochemical composition of seaweeds varies with environmental state of marine ecosystem. Eritrea, with long coastline bears diversified ecosystems and abundant seaweeds. But limited knowledge on nutritional importance and processing methods mitigate the dietary utilization of seaweeds by coastal community in the country. The present study focuses mainly on the analysis of biochemical composition of various seaweeds collected around the Massawa coast of Red Sea, Eritrea. The major biochemical components like proteins, carbohydrates, fats, fibre and ash were determined to establish the nutritional importance of the seaweeds. The high protein content was found in green seaweed Enteromorpha clathrata (13.64 %), whereas the brown seaweed Sargassum subrepandum has reported with high carbohydrates (28.11 %) and Cystoseira myrica has shown high fibre (32.39 %) content. The green seaweed Entermorpha compressa was found to be rich in fats (1.83 %), and high ash content (50.91 %) was recorded in brown seaweed Dictyota ciliolata. Page(s): 1153-1157