Indian Institute of Technology Guwahati

About: Indian Institute of Technology Guwahati is a education organization based out in Guwahati, Assam, India. It is known for research contribution in the topics: Adsorption & Catalysis. The organization has 6933 authors who have published 17102 publications receiving 257351 citations.

Detecting image spam using visual features and near duplicate detection

Abstract: Email spam is a much studied topic, but even though current email spam detecting software has been gaining a competitive edge against text based email spam, new advances in spam generation have posed a new challenge: image-based spam. Image based spam is email which includes embedded images containing the spam messages, but in binary format. In this paper, we study the characteristics of image spam to propose two solutions for detecting image-based spam, while drawing a comparison with the existing techniques. The first solution, which uses the visual features for classification, offers an accuracy of about 98%, i.e. an improvement of at least 6% compared to existing solutions. SVMs (Support Vector Machines) are used to train classifiers using judiciously decided color, texture and shape features. The second solution offers a novel approach for near duplication detection in images. It involves clustering of image GMMs (Gaussian Mixture Models) based on the Agglomerative Information Bottleneck (AIB) principle, using Jensen-Shannon divergence (JS) as the distance measure.

Microbial conversion of glycerol: present status and future prospects.

Abstract: Biodiesel has emerged as a potential alternate renewable liquid fuel in the past two decades Total annual production of biodiesel stands at 696 million tons and 112 million tons in USA and Europe, respectively In other countries, Asia and Latin America, biodiesel production has increased at unprecedented rate Despite this, the economy of biodiesel is not attractive An obvious solution for boosting the economy of the biodiesel industry is to look for markets for side products of the transesterification process of biodiesel synthesis The main by-product is glycerol However, this glycerol is contaminated with alkali/acid catalyst and alcohol, and thus, is not useful for conventional applications such as in toothpaste, drugs, paints and cosmetics Conversion of this glycerol to value-added product is a viable solution for effective and economic utilization, which would also generate additional revenue for the biodiesel industry Intensive research has taken place in area of conversion of glycerol to numerous products The conventional catalytic route of glycerol transformation employs prohibitively harsh conditions of temperature and pressure, and thus, has slim potential for large-scale implementation In addition, the selectivity of the process is rather small with formation of many undesired side products The bioconversion processes, on the other hand, are highly selective although with slower kinetics In this review, we have given an assessment and overview of the literature on bioconversion of glycerol We have assessed as many as 23 products from glycerol bioconversion, and have reviewed the literature in terms of microorganism used, mode of fermentation, type of fermentor, yield and productivity of the process and recovery/purification of the products The metabolic pathway of conversion of glycerol to various products has been discussed We have also pondered over economic and engineering issues of large-scale implementation of process and have outlined the constraints and limitations of the process We hope that this review will be a useful source of information for biochemists, biotechnologists, microbiologists and chemical engineers working in the area of glycerol bioconversion