Testing of low-voltage ride through capability compliance of wind turbines – a review

The increasing grid integration of wind power has led to the compulsory requirement of low-voltage ride through capability (LVRT) in wind turbines. Grid codes for LVRT capability of wind turbines are proposed in all major wind-energy-producing countries. The testing of LVRT capability compliance of the wind generators as per the specified grid codes during different fault conditions is essential to ensure its reliability. The testing process is generally done by the manufacturers and crucial for certification as per the IEC 61400-21 international standard for measurement of power quality characteristics of wind turbines. This review analyses the various testing tools under the software- and hardware-based categories. The review helps in understanding the present challenges in implementation of wind turbines, to alleviate the difficulty in LVRT testing procedures.     

Treatment of seafood industrial wastewater coupled with electricity production using air cathode microbial fuel cell under saline condition

The present study investigated seafood industrial wastewater treatment with corresponding power generation in air cathode microbial fuel cell under saline condition (40 g/L). The results recorded total chemical oxygen demand) removal of 52 ± 1.8%, 64 ± 1.1%, 85 ± 1.2%, 89 ± 1.4%, and 76 ± 1.2% to the corresponding organic load (OL) of 0.5, 0.75, 1, 1.25, and 1.5 gCOD/L under saline condition. Soluble chemical oxygen demand reduction was in the range of 46% to 78% at OL of 0.5 to 1.5 gCOD/L. The maximum power density (530 ± 15 mW/m²) and coulombic efficiency (52 ± 2.4%) was procured at the OL of 1.25 and 0.5 gCOD/L, respectively. Total suspended solids removal was 74 ± 1.5% at OL of 1.25 gCOD/L and 64 ± 1.3% at OL 1.5 gCOD/L. Bacterial community analysis for anode region samples for OL 0.5 and 1 gCOD/L was extensively dominated by Bacillus (MN880233) with 75.8% and 55.8%, respectively. Interestingly at 1.25 gCOD/L OL, Rhodococcus (MN880237) was predominant (42.3%) strain in the anode region and recorded high power production under saline condition. Sludge samples subjected to phylogenetic analysis explored the dominance of Clostridium, Turicibacter, and Marinobacter at different OL from 0.5 to 1.5 gCOD/L. Bacterial community results at 1.25 gCOD/L of OL sludge samples revealed completely different strains of dominancy in the community. Marinobacter (53.3%), Ochrobactrum (19.3%), and Bacillus (8.1%). Thus, the phylogenetic analysis of the anodic and sludge samples clearly detailed the presence of halophilic bacterial strains with high potential to treat seafood processing industrial wastewater and excellent exoelectrogenic activity for power production.     

DACASN: Dynamic ant routing‐based channel accessing cognitive sensor network in Internet of Things

The Internet of Things (IoT) is a structure with sensors, base station, gateway, and network servers. Users can access the information contained in it and use it as they need. These sensors are embedded in several data collection locations in a uniform or random manner to collect data. The users in many parts of the world obtain such data that fit their requirements. For example, sensors are used in remote areas to monitor various areas such as forests, wildlife sanctuaries, fields, industrial needs, human condition, and changes in the ocean. The changes like these that take place in the open spaces require the selection of the best routing method and seamless delay reduction in data collection helps to immediately reach those involved in it. In the proposed protocol, dynamic ant routing‐based channel accessing cognitive sensor network (DACASN) in the IoT, cognitive sensors are used. It is made with the knowledge of choosing a channel for communication as well as selecting the parameters for path selection and setting the most accurate path with the channel knowledge and communicating with the internet server. The sensors set the paths for this route selection using the centrifugal method and the anticolonial method. As a result, it can be seen in the results and discussion section that the quality of the routing information is high because it is delivered to the destination in the shortest possible time.     

Clinical decision support system for early prediction of Down syndrome fetus using sonogram images

In this paper, the segmentation and extraction of features from ultrasound second trimester fetal images have been presented for early detection of Down syndrome. The region of interest and the edges of the segmented region have been obtained using mean shift analysis and Canny operator, respectively. The prime features such as the nasal bone, the palate and the frontal bone have been segmented for estimating the nasal bone length and frontomaxillary facial angle (FMF). It is observed from the results that the rate of growth of nasal bone length is poor and the FMF angle has been found to increase above 85° for fetus with trisomy 21. This analysis may help the physician for better clinical diagnosis.     

Identification of Bioactive Candidate Compounds Responsible for Oxidative Challenge from Hydro‐Ethanolic Extract of Moringa oleifera Leaves

Free radicals trigger chain reaction and inflict damage to the cells and its components, which in turn ultimately interrupts their biological activities. To prevent free radical damage, together with an endogenous antioxidant system, an exogenous supply of antioxidant components to the body in the form of functional food or nutritional diet helps undeniably. Research conducted by the Natl. Inst. of Health claimed that Moringa oleifera Lam possess the highest antioxidant content among various natural food sources based on an oxygen radical absorbent capacity assay. In this study, a 90% (ethanol:distilled water—90:10) gradient solvent was identified as one of the best gradient solvents for the effectual extraction of bioactive components from M. oleifera leaves. This finding was confirmed by various antioxidant assays, including radical scavenging activity (that is, 1, 1‐diphenyl‐2‐picrylhydrazyl, H₂O₂, and NO radical scavenging assay) and total antioxidant capacity (that is, ferric reducing antioxidant power and molybdenum assay). High‐performance liquid chromatography (HPLC) fingerprints of the 90% gradient extract visually showed few specific peaks, which on further analysis, using HPLC–DAD–ESI–MS, were identified as flavonoids and their derivatives. Despite commonly reported flavonoids, that is, kaempferol and quercetin, we report here for the 1st time the presence of multiflorin‐B and apigenin in M. oleifera leaves. These findings might help researchers to further scrutinize this high activity exhibiting gradient extract and its bio‐active candidates for fruitful clinical/translational investigations.     

In vitro antibacterial,cytotoxicity and haemolytic activities and phytochemical analysis of seagrasses from the Gulf of Mannar,South India

It is essential to study the phytochemical constituents and toxicological properties of seagrasses when considering their food applications. Aqueous methanolic extracts of six seagrasses were evaluated for their antibacterial, cytotoxic (brine shrimp leathality assay) and haemolytic activity. Thin layer chromatography (TLC) and phytochemical analysis were used to compare the phytochemical profiles of six seagrasses. Among the six seagrasses examined, Halodule pinifolia and Cymodocea rotundata showed predominant growth inhibitory activity against all the tested human pathogens. Cytotoxicity of seagrass extracts against nauplii of Artemia salina revealed that Syringodium isoetifolium exhibited lesser toxicity with LC₅₀ value of 699.096 μg/ml. Of all the seagrasses tested, H. pinifolia recorded the minimum haemolytic activity of 2.07 ± 0.63% at 1000 μg/ml concentration. Phytochemical analysis showed the presence of common plant chemical constituents which varied with respect to species. The present findings suggest the possible pharmacological applications of selected seagrasses that can be used as food ingredients.     

Two-dimensional DOA estimation of coherent signals using acoustic vector sensor array

In this paper, we present two new methods for estimating two-dimensional (2-D) direction-of-arrival (DOA) of narrowband coherent (or highly correlated) signals using an L-shaped array of acoustic vector sensors. We decorrelate the coherency of the signals and reconstruct the signal subspace using cross-correlation matrix, and then the ESPRIT and propagator methods are applied to estimate the azimuth and elevation angles. The ESPRIT technique is based on the shift invariance property of array geometry and the propagator method is based on partitioning of the cross-correlation matrix. The propagator method is computationally efficient and requires only linear operations. Moreover, it does not require any eigendecomposition or singular-value decomposition as for the ESPRIT method. These two techniques are direct methods which do not require any 2-D iterative search for estimating the azimuth and the elevation angles. Simulation results are presented to demonstrate the performance of the proposed methods.     

Screening of edible mushrooms and extraction by pressurized water (PWE) of 3-hydroxy-3-methyl-glutaryl CoA reductase inhibitors

The methanol/water and particularly the water extracts obtained from 26 mushroom species were able to inhibit the 3-hydroxy-3-methyl-glutaryl CoA reductase (HMGCR) activity to different extent (10–76%). Cultivated mushrooms such as Pleurotus sp. and Lentinula edodes were among the strains which showed higher HMGCR inhibitory capacities. Their inhibitory properties were not largely influenced by cultivation parameters, mushroom developmental stage or flush number. The HMGCR inhibitory activity of L. edodes was concentrated in the cap excluding the gills while in Pleurotus ostreatus it was distributed through all the different tissues. A method to obtain aqueous fractions with high HMGCR inhibitory activity was optimized using an accelerated solvent extractor (ASE) by selecting 10.7 MPa and 25 °C as common extraction conditions and 5 cycles of 5 min each for P. ostreatus fruiting bodies and 15 cycles of 5 min for L. edodes suggesting that the potential HMGCR inhibitors are different in the two selected mushrooms.