National Institute of Technology, Silchar

About: National Institute of Technology, Silchar is a education organization based out in Silchar, Assam, India. It is known for research contribution in the topics: Computer science & Control theory. The organization has 1934 authors who have published 4219 publications receiving 41149 citations. The organization is also known as: NIT Silchar.

Clear-Water Scour at Abutments in Thinly Armored Beds

Abstract: Experiments on local scour at short abutments (ratio of abutment length to approaching flow depth less than unity), namely vertical-wall, 45° wing-wall, and semicircular, embedded in a bed of relatively fine noncohesive sediment overlain by a thin armor-layer of coarser sediment, were conducted for different flow conditions, thickness of armor-layers, armor-layer, and bed sediments. The abutments were aligned with the approaching flow in a rectangular channel. The armor-layer and the bed underneath it were composed of different combinations of uniform sediments. In the experiments, the approaching flow velocities were restricted to the clear-water scour condition with respect to the armor-layer particles. Depending on the approaching flow conditions, three cases of scour at abutments in armored beds were identified. Effects of different parameters pertaining to scour at abutments are examined. The comparison of the experimental data shows that the scour depth at an abutment with an armor-layer in clear-water scour condition under limiting stability of the surface particles (approaching flow velocity nearly equaling critical velocity for the threshold motion of surface particles) is always greater than that without armor-layer for the same bed sediments. The characteristic parameters affecting the maximum equilibrium nondimensional scour depth (scour depth-abutment length ratio), identified based on the physical reasoning and dimensional analysis, are excess abutment Froude number, flow depth-abutment length ratio, armor-layer thickness-armor particle diameter ratio, and armor particle-bed sediment diameter ratio. The experimental data of clear-water scour condition in thinly armored beds under limiting stability of surface particles were used to determine the equation of maximum equilibrium scour depth through regression analysis. The estimated scour depths were in agreement with the experimental scour depths. Also, an equation of maximum equilibrium scour depth in uniform sediments was obtained.

The strength and microstructural behavior of lime stabilized subgrade soil in road construction

Abstract: This paper attempts to study the potential of lime on strength and bearing capacity improvement of subgrade soil. The effect of soil type, different lime percentages (3, 5, 7 and 9%) and curing duration (0, 7, 14 and 28 days) on the engineering properties of soil is evaluated by conducting series of laboratory tests such as linear shrinkage, unconfined compressive strength (UCS), split-tensile strength (STS) and California bearing ratio (CBR) test. The result indicates that soil with large clay fractions needs a relatively higher percentage of lime to alter their physicochemical characteristics. Addition of lime reduced the linear shrinkage strains and increased the UCS, STS and CBR value of soil. But beyond an optimum lime content opposite trend is observed. The strength improvement of lime stabilized soil is further enhanced with curing time. Moreover, the micro-structural analyses are performed to understand the mechanisms involved in the lime stabilization process. Change in soil morphology fr...

A simple approach for the synthesis of silver nanoparticles and their application as a catalyst for the photodegradation of methyl violet 6B dye under solar irradiation

Abstract: In the present study, we established for the first time a simple method for the preparation of silver nanoparticles (Ag NPs) using saturated fatty acid and tryptophan as capping and reducing agent, respectively. The -NH2 group of tryptophan and the carboxylate group of saturated long chain carboxylate endow them as reducing and stabilising property respectively. The -NH2 group of the tryptophan reduced the Ag+ ions while the carboxylate group bounded strongly to the surface of the nanoparticles (NPs). This approach is a very special, size controlled synthetic approach for the large-scale synthesis of Ag NPs. The sizes of the synthesised Ag NPs were controlled by varying the processing parameters, such as reaction time and the chain length of the silver carboxylate (C12–C16). Studies showed that the particle size of Ag NPs increases with increase in reaction time and carbon chain length. The synthesised Ag NPs were characterized by ultra-violet spectroscopy (UV–vis), transmission electron spectroscopy (TEM), selected area electron diffraction (SAED), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The synthesised Ag NPs was used to evaluate the photo catalytic degradation of the methyl violet 6B dye under solar irradiation. The efficiency and rate of photo degradation of methyl violet 6B dye were also studied.