Fish productivity: Assessing sustainability in a tropical oxbow lake of Nadia district, West Bengal, India

Fish productivity in oxbow lake is impacted severely due to varied unsustainable anthropogenic practices like over exploitation, indiscriminate use of fine meshed fishing gears, jute retting etc. This particular study was conducted in a semi closed oxbow lake ecosystem in eastern India to assess both the present and sustainable fish productivity based on the data collected through direct catch assessment survey, fishing effort survey and catch per unit effort calculation. Hike in relative abundance values like numbers of fish catch (>3.78 times), catch per gear effort (>2.6 times), fish density (>2.65 times) and fall in relative biomass values like catch per gear effort, catch per unit effort and fish standing biomass (>41%) were observed during monsoon compared to premonsoon due to flooded turbid water from the river Ganga and jute retting processes during monsoon. Jute retting and indiscriminate over fishing of the monsoon made fish production reduced by >50% during post monsoon. The current fish productivity was estimated at 1146.64kg/ha/year supporting only 23.33% livelihoods of enlisted fishers and about 97.67% of fish production remains unreported every year in the official records of the cooperative society based on the oxbow lake ecosystem indicating inefficient management. Total sustainable production of 285MT (@5MT/ha/year) with total operating capital need of INR 1.00 crore (@INR 0.01716 crore/ha/year) with benefit cost ratio of 4.28 was estimated as the sustainable and replicable basis for promotion of organic aquaculture supporting 100% livelihoods of all fishers and rejuvenating the management of the present oxbow lake ecosystem

Impact of jute retting on physicochemical profile of Chhariganga oxbow lake in Nadia district, West Bengal, India

The present study was carried out to assess the ecosystem of the Chhariganga, an oxbow lake in eastern India to assess the pollution due to jute retting and trophic status on broader aspects for its sustainable management. The physicochemical analyses of the studied oxbow lake showed the range with annual mean values of surface water temperature in ºC (11-37, 27.64±6.56), water transparency in cm (16-106, 45.82±23.39), water pH (7.4-8.8, 8.17±0.34), DO (2.60-7.85, 4.65±1.52 ppm), BOD (1.10-6.40, 2.98±1.59ppm), COD (70-90, 79±7.38ppm), NH4-N (0.026-0.093, 0.05±0.02ppm), NO2-N (0.008-0.08, 0.03±0.02ppm), NO3-N (0-2.459, 0.81±0.69ppm), OP (0.067-0.62, 0.26±0.18ppm), total alkalinity (82-165, 120±24.03ppm), total hardness (70-138, 102.62±19.60ppm), GPP (0.30-1.80, 1.25± 0.47mgC/l/day), NPP (0.15-1.38, 0.95± 0.40mgC/l/day); sediment pH (6.8-7.9, 7.53±0.34) and sediment organic carbon in % (1.87-2.89, 2.17±0.28). The highest mean values of BOD (4.59ppm), COD (86.67ppm), OP (0.50ppm), sediment organic carbon (2.29%) were observed during monsoon whereas the lowest values of oxbow lake water’s transparency (27.00cm), pH (7.84), DO (3.63ppm) and NO2–N (0.01 ppm) contents were found during monsoon when jute retting process intensified in the oxbow lake. Compared to their values in pre-monsoon, mean values in monsoon showed an increase in BOD (182.57%) and OP content (167.64%) unlike reduction in water transparency (62.54%), GPP and NPP (both reduced by about 50%); The highest concentration of NH4-N and NO3-N were noticed during post-monsoon and OP during monsoon. The water transparency mean values showed sharp fall during monsoon from pre-monsoon. Physico-chemical analyses revealed that almost all parameters in oxbow lake did not show significant changes throughout the year unlike water transparency, BOD, NO2 and especially OP content of water which otherwise showed significant changes throughout the year.  The present semi-closed oxbow lake water was of poor to moderate quality and it was classified as oligo-mesotrophic in nutrient status with high to moderate organic pollution due to jute retting process which needs to be controlled and regulated for sustainable aquaculture in oxbow lake ecosystem

Detection and Identification of Camouflaged Targets using Hyperspectral and LiDAR data

Camouflaging is the process of merging the target with the background with the aim to reduce/delay its detection. It can be done using different materials/methods such as camouflaging nets, paints. Defence applications often require quick detection of camouflaged targets in a dynamic battlefield scenario. Though HSI data may facilitate detection of camouflaged targets but detection gets complicated due to issues (spectral variability, dimensionality). This paper presents a framework for detection of camouflaged target that allows military analysts to coordinate and utilise the expert knowledge for resolving camouflaged targets using remotely sensed data. Desired camouflaged target (set of three chairs as a target under a camouflaging net) has been resolved in three steps: First, hyperspectral data processing helps to detect the locations of potential camouflaged targets. It narrows down the location of the potential camouflaged targets by detecting camouflaging net using Independent component analysis and spectral matching algorithms. Second, detection and identification have been performed using LiDAR point cloud classification and morphological analysis. HSI processing helps to discard the redundant majority of LiDAR point clouds and support detailed analysis of only the minute portion of the point cloud data the system deems relevant. This facilitates extraction of salient features of the potential camouflaged target. Lastly, the decisions obtained have been fused to infer the identity of the desired targets. The experimental results indicate that the proposed approach may be used to successfully resolve camouflaged target assuming some a priori knowledge about the morphology of targets likely to be present.

Development of a gravimetric geoid model and a comparative study

Site specific geoid model is prerequisite for accurate determination of orthometric heights. No geoid model has been developed so far for India or any of its part. So, development of a geoid model for India or its part is of utmost need to make use of GNSS data towards determination of orthometric heights. In this research work, an attempt has been made to develop geoid undulation models by gravimetric method using Molodensky’s concept. Component parameters in line with the Remove – Compute – Restore (RCR) technique have been used recursively. Models have been developed for two study areas: one of these lies in and around Dehradun (30° 19′ N, 75° 04′E) in Uttarakhand state, India in lower Himalayan region having highly undulating topography and the other near Hyderabad (17° 30′N, 78°30′E) in Telengana state of India having gentle topography. The model has been tested for 7 stations in the first study area and accuracy has been found to be 17.5 cm; whereas, for the second area accuracy has been found to be 7.0 cm for 24 test stations. Further, the performances of the developed models have been evaluated with those from three global geoid models namely EIGEN6C4, EIGEN6C3stat and EGM2008; and have been found to be similar or better in case of first study and for second study area far more superior. Thus, local/regional geoid undulation model requiring accuracy better than 20 cm for any study area may be developed adopting the method. However, the optimality in the number and density of gravity stations may be considered as a future scope of work

An efficient source localization method in presence of multipath using smart antenna system

In this paper, a MATLAB based smart antenna testbed that efficiently localizes the line-of-sight (LOS) source in the presence of multipath signals is developed. By exploiting the consistent amplitude nature of the LOS signal, a variant of Constant Modulus Algorithm, namely Multitarget-Least Square Constant Modulus Algorithm is employed to adapt and update the weights of the smart antenna for estimation of the direction-of-arrival (DOA) of the of the LOS and multipath interference signals. Performance is compared with the conventional and recently proposed algorithms in the same testbed with alike considerations. Simulation result shows that the proposed method of DOA estimation performs better in terms of probability of resolution and root mean square error

An Efficient Source Localization Method in Presence of Multipath using Smart Antenna System

1069-1073In this paper, a MATLAB based smart antenna testbed that efficiently localizes the line-of-sight (LOS) source in the presence of multipath signals is developed. By exploiting the consistent amplitude nature of the LOS signal, a variant of Constant Modulus Algorithm, namely Multitarget-Least Square Constant Modulus Algorithm is employed to adapt and update the weights of the smart antenna for estimation of the direction-of-arrival (DOA) of the of the LOS and multipath interference signals. Performance is compared with the conventional and recently proposed algorithms in the same testbed with alike considerations. Simulation result shows that the proposed method of DOA estimation performs better in terms of probability of resolution and root mean square error

Study on the Perspective of Mechanical Properties and Corrosion Behaviour of Stainless Steel, Plain and TMT Rebars

In the present research, the effects of various alloying elements and microstructural constituents on the mechanical properties and corrosion behaviour have been studied for four different rebars. The microstructures of stainless steel and plain rebar primarily reveal equiaxed ferrite grains and ferrite-pearlite microstructures, respectively, with no evidence of transition zone, whereas tempered martensite at the outer rim, followed by a narrow bainitic transition zone with an internal core of ferrite-pearlite, has been observed for the thermomechanically treated (TMT) rebars. The hardness profiles obtained from this study display maximum hardness at the periphery, which decreases gradually towards the centre, thereby providing the classical U-shaped hardness profile for TMT rebars. The tensile test results confirm that stainless steel rebar exhibits the highest combination of strength (≈755 MPa) and ductility (≈27%). It has been witnessed that in Tafel plots, the corrosion rate increases for all the experimental rebars in 1% HCl solution, which is well expected because the acid solutions generally possess a higher corrosive environment than seawater (3.5% NaCl) due to their acidic nature and lower pH values. However, all the experimental results obtained from Tafel and Nyquist plots correlate well for both 1% HCl and 3.5% NaCl solutions