scholarly journals Tribological Properties of Different Types of Graphene Nanoplatelets as Additives for the Epoxy Resin

2020 ◽  
Vol 10 (12) ◽  
pp. 4363
Author(s):  
Mónica Campo ◽  
Alberto Jiménez-Suárez ◽  
Alejandro Ureña

The use of graphene nanoplatelets for several purposes such as barrier properties and structural health monitoring is widely studied in polymer-based coating technology. Nevertheless, their extremely good effect on wear resistance makes them particularly interesting for coating technology. The effect of graphene nanoplatelets addition on the wear behaviour of an epoxy resin was analysed. The effects of graphene nanoplatelets content (0–8 wt.%), morphology and functionalization in wear behaviour were analysed by evaluating the main wear parameters of the nanocomposites studied. The morphology of the wear surfaces was analysed by scanning electron microscopy (SEM) and 3D optical profilometry in order to evaluate the mechanism and severity of wear. The results showed that the wear behaviour of the epoxy resin improved considerably with the addition of graphene, especially for higher contents. Moreover, as the wear mechanism depends on the morphology of graphene nanoplatelets, it was concluded that the proper selection of graphene can be made depending on the chosen application.

Author(s):  
M A Rabah ◽  
S M Eldighidy ◽  
A A Abdul Azim

The lifetime of mechanical carbon sealing rings fitted into crude petroleum oil pumps can be increased by a factor of 43 by multiple impregnation with coal tar pitch. For single impregnation, epoxy resin yielded the largest improvement. The results were interpreted on the premise that properties such as viscosity, adhesion forces, and coking value determine the effectiveness of the impregnant. The proper selection of the impregnant and procedure of impregnation is dependent on the pumping pressure and oil properties.


2009 ◽  
Vol 63 (5) ◽  
pp. 377-385
Author(s):  
Dragan Milanovic ◽  
Zoran Markovic

The aim of this work was to study floatability of the mineral sheelite from mine 'Rudnik', central Serbia. Flotation tests of the mineral in a Hallimond tube cell were carried out in four different types of water, namely: tap water, distilled water, rain water and spring water. All types of water had different hardness and conductivity as well as natural pH values. It was found that the flotability of mineral scheelite depends on the hardness and electro-conductivity of the chosen type of water as well as on Ca2+ content. Also, it was found the floatability of mineral depends on the scheelite particle size fraction used in microflotation experiments. Presented results may be useful for proper selection of type of water, as well of the type of reagents used in flotation processes.


2018 ◽  
Vol 178 ◽  
pp. 05009
Author(s):  
Elena Amaricai

In rehabilitation medicine there is increasing need of using high quality orthoses that can provide either good stability of the joint or good correction of the postural defect. The advantages of using orthoses that are in the same time hypoallergenic, lightweight, flexible, resistant and durable over time should be considered when prescribing them in clinical practice. This study presents different types of orthoses and the necessity of proper selection of materials when choosing the best ones. We included 34 patients diagnosed with different musculoskeletal conditions (thoracic and thoraco-lumbar scoliosis, genu valgum deviation and rheumatoid arthritis) that required the use of special orthoses (thoraco-lumbar braces, knee or hand orthoses). Patients were asked to complete a questionnaire regarding the quality of the orthoses that they have been used. The following characteristics of an orthosis should be considered when choosing the right one: easily wearable, comfortable, offering good stability of a joint, high quality, lightweight, hypoallergenic and resistant.


2017 ◽  
Vol 10 (1) ◽  
pp. 32-52
Author(s):  
Bonnie White

In 1917 the British government began making plans for post-war adjustments to the economy, which included the migration of surplus women to the dominions. The Society for the Overseas Settlement of British Women was established in 1920 to facilitate the migration of female workers to the dominions. Earlier studies have argued that overseas emigration efforts purposefully directed women into domestic service as surplus commodities, thus alleviating the female ‘surplus’ and easing economic hardships of the post-war period. This article argues that as Publicity Officer for the SOSBW, Meriel Talbot targeted women she believed would be ideal candidates for emigration, including former members of the Women's Land Army and affiliated groups. With the proper selection of female migrants, Talbot sought to expand work opportunities for women in the dominions beyond domestic service, while reducing the female surplus at home and servicing the connection between state and empire. Dominion authorities, whose demands for migrant labour vacillated between agricultural workers during the war years and domestic servants after 1920, disapproved of Talbot's efforts to migrate women for work in agriculture. Divergent policies led to the early failure of the SOSBW in 1923.


Agrotek ◽  
2018 ◽  
Vol 3 (2) ◽  
Author(s):  
Baso Daeng

<em>The rate of conversion of paddy fields and irrigation water crisis suggest to consider the development of upland rice.� Empowerment of organic-based dryland done to increase rice, as well as environmental sustainability efforts.� The purpose of this experiment was to determine the effect of organic fertilizer residue to upland rice in the second growing season.� Experiments using a split-split plot design.� The main plot consisted of a dosage of 50% and 100% organic fertilizer in the first growing season.� Sub plot consisted of chicken manure (20 tons ha<sup>-1</sup>), <span style="text-decoration: underline;">Centrosema</span>� <span style="text-decoration: underline;">pubescens</span> (4.3 tons ha<sup>-1</sup>) + chicken manure (10 tons ha<sup>-1</sup>), and <span style="text-decoration: underline;">Thitonia</span> <span style="text-decoration: underline;">diversifolia</span> (4.3 tons ha<sup>-1</sup>) + chicken manure (10 tons ha<sup>-1</sup>).� Sub-sub plot consist of Danau Gaung and Batu Tegi varieties.� The different types of fertilizer had no effect on plant productivity.� The addition of <span style="text-decoration: underline;">Thitonia</span> <span style="text-decoration: underline;">diversifolia</span> gave a good effect on some growth variable and its resistance due pathogen attack.� Batu Tegi varieties are varieties that give the best response from an organic fertilizer.� Interaction between dosage, type of fertilizer, and varieties do not provide areal impact.</em>


2021 ◽  
Vol 13 (4) ◽  
pp. 2146
Author(s):  
Anik Gupta ◽  
Carlos J. Slebi-Acevedo ◽  
Esther Lizasoain-Arteaga ◽  
Jorge Rodriguez-Hernandez ◽  
Daniel Castro-Fresno

Porous asphalt (PA) mixtures are more environmentally friendly but have lower durability than dense-graded mixtures. Additives can be incorporated into PA mixtures to enhance their mechanical strength; however, they may compromise the hydraulic characteristics, increase the total cost of pavement, and negatively affect the environment. In this paper, PA mixtures were produced with 5 different types of additives including 4 fibers and 1 filler. Their performances were compared with the reference mixtures containing virgin bitumen and polymer-modified bitumen. The performance of all mixes was assessed using: mechanical, hydraulic, economic, and environmental indicators. Then, the Delphi method was applied to compute the relative weights for the parameters in multi-criteria decision-making methods. Evaluation based on distance from average solution (EDAS), technique for order of the preference by similarity to ideal solution (TOPSIS), and weighted aggregated sum product assessment (WASPAS) were employed to rank the additives. According to the results obtained, aramid pulp displayed comparable and, for some parameters such as abrasion resistance, even better performance than polymer-modified bitumen, whereas cellulose fiber demonstrated the best performance regarding sustainability, due to economic and environmental benefits.


Author(s):  
D. Josephine Selvarani Ruth

AbstractNickel Titanium Naval Ordinance Laboratory (NiTiNOL) is widely called as a shape memory alloy (SMA), a class of nonlinear smart material inherited with the functionally programmed property of varying electrical resistance during the transformation enabling to be positioned as a sensing element. The major challenge to instrument the SMA wires is to suppress the wires’ nonlinearity by proper selection of two important factors. The first factor is influenced by the mechanical biasing element and the other is to identify the sensing current for the sensing device (SMA wires + biasing). This paper focuses on developing SMA wires for sensing in different orientation types and configurations by removing the non-linearity in the system’s output by introducing inverse hysteresis to the wires through the passive mechanical element.


2021 ◽  
Vol 11 (11) ◽  
pp. 5235
Author(s):  
Nikita Andriyanov

The article is devoted to the study of convolutional neural network inference in the task of image processing under the influence of visual attacks. Attacks of four different types were considered: simple, involving the addition of white Gaussian noise, impulse action on one pixel of an image, and attacks that change brightness values within a rectangular area. MNIST and Kaggle dogs vs. cats datasets were chosen. Recognition characteristics were obtained for the accuracy, depending on the number of images subjected to attacks and the types of attacks used in the training. The study was based on well-known convolutional neural network architectures used in pattern recognition tasks, such as VGG-16 and Inception_v3. The dependencies of the recognition accuracy on the parameters of visual attacks were obtained. Original methods were proposed to prevent visual attacks. Such methods are based on the selection of “incomprehensible” classes for the recognizer, and their subsequent correction based on neural network inference with reduced image sizes. As a result of applying these methods, gains in the accuracy metric by a factor of 1.3 were obtained after iteration by discarding incomprehensible images, and reducing the amount of uncertainty by 4–5% after iteration by applying the integration of the results of image analyses in reduced dimensions.


2021 ◽  
pp. 1-21
Author(s):  
Muhammad Shabir ◽  
Rimsha Mushtaq ◽  
Munazza Naz

In this paper, we focus on two main objectives. Firstly, we define some binary and unary operations on N-soft sets and study their algebraic properties. In unary operations, three different types of complements are studied. We prove De Morgan’s laws concerning top complements and for bottom complements for N-soft sets where N is fixed and provide a counterexample to show that De Morgan’s laws do not hold if we take different N. Then, we study different collections of N-soft sets which become idempotent commutative monoids and consequently show, that, these monoids give rise to hemirings of N-soft sets. Some of these hemirings are turned out as lattices. Finally, we show that the collection of all N-soft sets with full parameter set E and collection of all N-soft sets with parameter subset A are Stone Algebras. The second objective is to integrate the well-known technique of TOPSIS and N-soft set-based mathematical models from the real world. We discuss a hybrid model of multi-criteria decision-making combining the TOPSIS and N-soft sets and present an algorithm with implementation on the selection of the best model of laptop.


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