Investigation of Surface Displacements Induced in Loaded Cross-Ply Composite Laminates with Microcracking

This work is aimed at investigating out-of-plane displacement data on the top surface of a loaded composite laminate containing microcracking damage to explore the feasibility of using surface data to locate microcracks in laminates. In this study, finite element models are created for eleven different cross-ply IM7/977-2 laminates with ply numbers varying from four to ten. Here, each ply thickness is 0.127mm, which is the common laminate thickness commercially available for this material system. For each model a range of transverse loadings are applied and the surface displacement data are analyzed along the mid-plane perpendicular to the plane of the crack. The following outof- plane surface data parameters are obtained for each case: the minimal value above the crack tip, the peak value, and the far-field value. The difference in the peak and minimal values for a given loading is important in determining whether or not the optical technique is sensitive enough to resolve the data. The lateral distance to the peak values and the far-field values are also obtained. These distances are important in determining whether or not an optical system can spatially resolve the data. Results suggest that an optical technique such as digital holography could resolve, at a minimum, the data of [0/90/90/0], [0/90/90/90/90/0], and [0/0/90/90/90/90/0/0] laminates subjected to transverse loads of 1000 MPa

Investigation of Surface Displacements Induced in Loaded Cross-Ply Composite Laminates with Microcracking

This work is aimed at investigating out-of-plane displacement data on the top surface of a loaded composite laminate containing microcracking damage to explore the feasibility of using surface data to locate microcracks in laminates. In this study, finite element models are created for eleven different cross-ply IM7/977-2 laminates with ply numbers varying from four to ten. Here, each ply thickness is 0.127mm, which is the common laminate thickness commercially available for this material system. For each model a range of transverse loadings are applied and the surface displacement data are analyzed along the mid-plane perpendicular to the plane of the crack. The following outof- plane surface data parameters are obtained for each case: the minimal value above the crack tip, the peak value, and the far-field value. The difference in the peak and minimal values for a given loading is important in determining whether or not the optical technique is sensitive enough to resolve the data. The lateral distance to the peak values and the far-field values are also obtained. These distances are important in determining whether or not an optical system can spatially resolve the data. Results suggest that an optical technique such as digital holography could resolve, at a minimum, the data of [0/90/90/0], [0/90/90/90/90/0], and [0/0/90/90/90/90/0/0] laminates subjected to transverse loads of 1000 MPa

Role of Surfactants in Mineral Processing: An Overview

Depletion of high-grade resources has necessitated the use of low-grade fines, which contain good amount of mineral values and also liberate in finer sizes. Froth flotation, a physico-chemical surface-based process, is the most established solution, both technologically and economically, compared to other alternatives for fines beneficiation. For a successful and effective flotation performance, an understanding of the mineral surface and proper selection of the surfactant/reagent regimes along with their molecular chemistry and their specific adsorption mechanism are mandated. This chapter focuses on the complexity of the flotation process along with adsorption and interaction mechanism of different surfactants in accordance to mineral surface characteristics and their dependency on many microevents. To further strengthen mineral flotation chemistry and advancement of mineral engineering, research gears at investigating new surfactants, specific for particular mineral surface. The selection of reagents/surfactants with appropriate chemical composition and their administration are of critical importance in view of varied mineralogy, chemical complexity and size consist of feed material. Cost- effective and lower cost flotation reagents can be synthesized through insertion of new functional groups, molecular modelling of reagents for more environment-friendly nature, modifying the structure of other chelating agents and novel green chemicals from renewable resources, adding aliphatic alcohol and carboxylic acid to bio-based collectors and adding chaotropic anions to alkyl and aryl surfactants and organic and inorganic salts having strong orientation with more proton donor and acceptor; addition of another cationic group to known cationic surfactants can be tried for enhanced flotation performance. The study also provides an idea on the effect of other parameters like pH, composition of pulp, zeta potential, electrostatic potential, etc. For envisagement of a successful flotation performance, proper selection of the reagent system according to the specific surface and understanding of the mineral surface-specific adsorption mechanism are mandated

Robust self-healing prediction model for high dimensional data

Owing to the advantages of increased accuracy and the potential to detect unseen patterns, provided by data mining techniques they have been widely incorporated for standard classification problems. They have often been used for high precision disease prediction in the medical field, and several hybrid prediction models capable of achieving high accuracies have been proposed. Though this stands true most of the previous models fail to efficiently address the recurring issue of bad data quality which plagues most high dimensional data, and especially proves troublesome in the highly sensitive medical data. This work proposes a robust self healing (RSH) hybrid prediction model which functions by using the data in its entirety by removing errors and inconsistencies from it rather than discarding any data. Initial processing involves data preparation followed by cleansing or scrubbing through context-dependent attribute correction, which ensures that there is no significant loss of relevant information before the feature selection and prediction phases. An ensemble of heterogeneous classifiers, subjected to local boosting, is utilized to build the prediction model and genetic algorithm based wrapper feature selection technique wrapped on the respective classifiers is employed to select the corresponding optimal set of features, which warrant higher accuracy. The proposed method is compared with some of the existing high performing models and the results are analyzed

Study of importance of coal fines processing and applicability of different processing routes for improving process efficiency

National Steel Policy 2017 envisages crude steel capacity to grow upto 300MTPA by 2030-31 and coal, being one of the major requirements, will play an important role in achieving the target. There are a few substitutes e.g. Biomass, Charcoal etc., which can be used in place of coal but none of them can replace coal entirely as of now. The reserves comprising of good quality coal are fast depleting. Hence, processing of low grade coal and effective usage of coal preparation plants (CPP) disposed tailings are of grave importance. Processing of coal fines are carried out by different beneficiation routes mainly froth flotation, autogenous cyclones etc. Liberation size is decreasing drastically and existing methods are inefficient to fully recover the fines. Applicability of two processes - selective flocculation and liquid-solid fluidization - on processing of coal fines of Eastern India have been attempted in this work. Different coal samples and size fractions have been taken to test the feasibility of the said beneficiation routes. While liquid-solid fluidization gave better results at relatively coarser sizes, results were good at finer sizes in selective flocculation of coal fines. Effect of operational parameters on the combustible recovery of coal fines and the process efficiency have been investigated

Solid-liquid fluidization & its applicability in mineral processing – An initial study on Iron ore fines

This paper highlights the potential application of solid-liquid fluidization in the beneficiation of iron ore fines. Liquid-fluidized beds are a type of gravity separators, which stratify the various minerals into layers according to their different specific gravity. A bed of particles of different size and density is fluidized by an upward and downward movement of water. The repeated fluidization allows settling and segregation of particles according to size & density. Decreasing ore grade and increasing tailings generation present difficulties in beneficiation by conventional methods such as flotation, selective flocculation as these methods are size and material/reagent specific. Hence, researchers have started using the fluidization process for the separation of valuable minerals trapped inside low-grade ores and fines/tailings. In the present study, hydrodynamics and fluidized bed behaviour of the iron ore fines have been studied. Physical phenomena such as pressure drop and bed expansion have been discussed in detail. Equations already exist in the literature for calculating these parameters. Calculated and experimental values have been compared. These phenomena as a function of feed size, static bed height, superficial water velocity have been observed and expressed in the form of graphs

Mining Duplicate Questions of Stack Overflow

There has a been a significant rise in the use of Community Question Answering sites (CQAs) over the last decade owing primarily to their ability to leverage the wisdom of the crowd. Duplicate questions have a crippling effect on the quality of these sites. Tackling duplicate questions is therefore an important step towards improving quality of CQAs. In this regard, we propose two neural network based architectures for duplicate question detection on Stack Overflow. We also propose explicitly modeling the code present in questions to achieve results that surpass the state of the art

Modular Approach to Machine Reading Comprehension: Mixture of Task-Aware Experts

In this work we present a Mixture of Task-Aware Experts Network for Machine Reading Comprehension on a relatively small dataset. We particularly focus on the issue of common-sense learning, enforcing the common ground knowledge by specifically training different expert networks to capture different kinds of relationships between each passage, question and choice triplet. Moreover, we take inspi ration on the recent advancements of multitask and transfer learning by training each network a relevant focused task. By making the mixture-of-networks aware of a specific goal by enforcing a task and a relationship, we achieve state-of-the-art results and reduce over-fitting

Application of Colloids and Its Relevance in Mineral Engineering

Mineral engineering is an interdisciplinary branch which includes many branches like physics, chemistry, math and sub branches like instrumentation, chemical engineering, mechanical engineering, geology etc. Amongst the various separation/beneficiation techniques of mineral processing, froth flotation is one of the most important fines beneficiation technique, which depends upon the surface and colloid chemical phenomena as the basis of selectivity. The method of separation relies on the surface state and colloidal chemistry of the ore particles and chemical reagents. Adsorption at the mineral solution interface is of major importance for the behaviour of mineral particles in the solution and for successful flotation performance. Adsorption of simple ions determine the change of the particle surface and electrochemical properties of the pulp/slurry phase and therefore affect the colloidal stability and the adsorption behaviour of reagent on the mineral surface. This chapter describes in detail about the role, importance and application of colloidal chemistry in mineral processing especially froth flotation. Froth flotation will remain a key unit operation for the treatment of low-grade ore fines for the decades to come with the overarching challenge as the need of the hour is to modify and improve existing process conditions so as to maintain an acceptable grade and recovery response for the feed whose liberation is more finer, more complex association of minerals and of lower grade