Delhi Technological University

About: Delhi Technological University is a education organization based out in New Delhi, India. It is known for research contribution in the topics: Computer science & Control theory. The organization has 4427 authors who have published 6761 publications receiving 71035 citations. The organization is also known as: Delhi College of Engineering & DTU.

Bio-inspired synthesis of microporous bioactive glass-ceramic using CT-DNA as a template

Abstract: We report, for the first time, bio-inspired synthesis of a bioactive glass-ceramic with superior textural properties in atmospheric conditions using CT-DNA as template. The phase composition, structure, morphology, and textural properties of the bioactive glass sample were evaluated with various analytical techniques before and after in vitro tests. The BET surface area analysis of the obtained glass-ceramic sample reveals that it possesses a high surface area with a range of (micro- to meso-) pore sizes. The TEM analysis of the glass-ceramic phase indicates that the amorphous phase consists of spherical particles, whereas the crystalline phase is found to have needle-like shape. In the glass-ceramic, we find a new type of crystalline phase (Na0.11Ca0.89)(P0.11Si0.89)O3, which is different from the earlier observation on 45S5® glass-ceramic sample. The accelerated in vitro bioactivity of the glass-ceramic is evidenced based on the hydroxyl carbonate apatite (HCA) layer formation on the glass-ceramic surface after immersing the bioglass sample in simulated body fluid (SBF), by FTIR, SEM and EDX analysis. Additionally, the ion release kinetics of the bioglass sample in SBF is followed by ICP-AES with simultaneous pH measurements. The in vitro cytotoxicity experiments on the glass-ceramic sample using osteosarcoma cells by following the MTT assay method indicate that the sample has good biocompatibility and may serve as an effective biomaterial for bone tissue engineering.

Regio- and Stereoselective Synthesis of Isoindolin-1-ones through BuLi-Mediated Iodoaminocyclization of 2-(1-Alkynyl)benzamides.

Abstract: A simple and straightforward synthesis of isoindolin-1-ones is reported. Exclusive N-cyclization of the amide functional group, an ambident nucleophile, was accomplished for the cyclization of 2-(1-alkynyl)benzamides using n-BuLi-I2/ICl. The methodology works with the primary amide and affords the desired isoindolinones in yields of 38–94%. Interestingly, the isolated products exhibit a Z-stereochemistry across the C═C double bond. The reaction mechanism involving the formation of either a vinylic anion or an intimate ion pair intermediate is proposed.

Effect of Friction Stir Processing on Mechanical Properties and Wear Resistance of Tungsten Inert Gas Welded Joint of Dissimilar Aluminum Alloys

Abstract: In this work, we examine TIG welded joints processed with friction stir processing at tool rotational speeds (TRSs) of 700, 800, 900, 1000, and 1100 rpm, with a constant feed rate of 70 mm/min and tilt angle of 1°. The percentage improvement in the tensile strength of TIG + FSP (TF) weldments was observed to be 78.57 and 75.89%, compared with TIG welded joints with ER4043 and ER5356 filler, respectively, at a TRS of 1100 rpm. A maximum tensile strength of 196 MPa was observed in a TF welded joint with ER5356 filler, and a minimum tensile strength of 98 MPa was observed in the TIG weldment with ER4043 filler. Cleavage facets, tear ridges, and large dimples were observed in fractured specimens of TIG welded joints, whereas fine, equiaxed dimples were observed in TF welded joints. A maximum micro-hardness of 137 HV in the stir zone was observed in TF welded joints at a TRS of 1100 rpm. TF welded joints with ER5356 filler had superior wear resistance compared to TIG and TF welded joints with ER4043 filler.

Effect on the Mechanical Properties of Aluminum-Based Hybrid Metal Matrix Composite Using Stir Casting Method

Abstract: Al based-Hybrid Metal Matrix Composites (HMMC) are becoming widely popular in the Automobile industry due to its highly attractive characteristics of enhanced hardness. The heterogeneous mixture formed due to the presence of reinforcement particles adds to the strength, wear resistance, hardness etc. to the specimen. In this research, fine ashes of bagasse (sugarcane), banana, and jute (coconut covering) were used, produced by burning the above in free atmosphere. The sample was sieve tested to 200 mesh size and ball milled in the presence of SiC with weight ratio of 1:2. Stir casting of the composite was performed in the melting furnace to produce different specimens of Al6061 consisting of different types of reinforcement. The specimens were then exposed to various tests to determine Ultimate tensile strength, yield strength, hardness, and percentage elongation. The best results termed out with the specimen reinforced with banana ash at the cost of loss in ductility exhibiting Ultimate tensile strength 115.4 MPa, Yield Strength 76.4 MPa, Vickers hardness 55-77 HV and Percentage elongation 21%.

Variational Autoencoders with Riemannian Brownian Motion Priors

Abstract: Variational Autoencoders (VAEs) represent the given data in a low-dimensional latent space, which is generally assumed to be Euclidean. This assumption naturally leads to the common choice of a standard Gaussian prior over continuous latent variables. Recent work has, however, shown that this prior has a detrimental effect on model capacity, leading to subpar performance. We propose that the Euclidean assumption lies at the heart of this failure mode. To counter this, we assume a Riemannian structure over the latent space, which constitutes a more principled geometric view of the latent codes, and replace the standard Gaussian prior with a Riemannian Brownian motion prior. We propose an efficient inference scheme that does not rely on the unknown normalizing factor of this prior. Finally, we demonstrate that this prior significantly increases model capacity using only one additional scalar parameter.