scholarly journals An analysis of the relative hardness of Reuters-21578 subsets

2005 ◽  
Vol 56 (6) ◽  
pp. 584-596 ◽  
Author(s):  
Franca Debole ◽  
Fabrizio Sebastiani
Keyword(s):  
Relative Hardness

Hybrid Metallic Coatings on Polymer-Based Composites

2021 ◽  
Author(s):  
Panteha Fallah ◽  
Stephen Yue ◽  
André McDonald
Keyword(s):  
Cold Spraying ◽  
Deposition Efficiency ◽  
Major Effect ◽  
Fiber Reinforced Polymers ◽  
Carbon Fiber Reinforced Polymers ◽  
Reinforced Polymers ◽  
Particle Layer ◽  
Cu Substrates ◽  
Relative Hardness ◽  
Cu Interlayer

Abstract A previous study showed that Cu can be cold sprayed onto carbon fiber-reinforced polymers (CFRPs) if a Cu interlayer is deposited prior to low-pressure cold spraying. In this present study, Cu was cold sprayed onto CFRP substrates that were coated with either Sn (cold spray) or Ni electroplating. Two layers of Cu powder were also cold sprayed onto a Cu-plated CFRP substrate to investigate the effect of a second particle layer on impacting particles. Test results showed that the relative hardness between the particle and substrate has a major effect on deformability, impact mode, and deposition efficiency (DE), which explains why Cu could not be cold sprayed onto Sn or Ni interlayers and why the deposition efficiency of Cu-on-Cu substrates is lower than that of one pass spraying. In summary, the results suggest that Cu can be successfully cold sprayed at low pressures onto electroplated Cu due to their similarity in hardness.

Part I. Friction of metals - Influence of oxide films on metallic friction

1952 ◽  
Vol 212 (1111) ◽  
pp. 450-452 ◽  
Keyword(s):  
Surface Damage ◽  
Metallic Contact ◽  
Degree Of Protection ◽  
Number Of Factors ◽  
Gold Silver ◽  
Zinc Cadmium ◽  
Natural Oxide ◽  
Lead Zinc ◽  
Relative Hardness ◽  
Metallic Friction

The mechanism of metallic friction, in air, has been investigated for loads ranging from 0.003 to 10000 g. The metals studied include platinum, gold, silver, copper, tin, lead, zinc, cadmium, magnesium, aluminium and chromium. The earlier work of Whitehead has been extended and simultaneous measurements made of the frictional force and the electrical resistance between the sliding surfaces. The results show that with most metals the natural oxide layer is sufficient to prevent metallic contact at very small loads. The degree of protection depends on a number of factors, such as the surface roughness, the thickness of the oxide film and in particular on the relative hardness of the oxide and the metal substrate. When sliding occurs solely on the oxide layers the friction is not necessarily less than that observed when appreciable metallic contact occurs. The surface damage is, however, greatly diminished on account of the reduced metallic interaction.

A novel nature-inspired optimization based neural network simulator to predict coal grindability index

2018 ◽  
Vol 35 (2) ◽  
pp. 1003-1048 ◽  
Author(s):  
S. Yazdani ◽  
Esmaeil Hadavandi ◽  
James Hower ◽  
Saeed Chehreh Chelgani
Keyword(s):  
Neural Network ◽  
Coal Industry ◽  
Network Simulator ◽  
Promising Alternative ◽  
Content Type ◽  
Evolutionary Neural Network ◽  
Coal Particles ◽  
Wide Range ◽  
Relative Hardness ◽  
Hardgrove Grindability Index

Purpose Hardgrove grindability index (HGI) is an important physical parameter used to demonstrate the relative hardness of coal particles. Modeling of HGI based on coal conventional properties is a quite complicated procedure. The paper aims to develop a new accurate model for prediction of HGI that is called optimized evolutionary neural network (OPENN). Design/methodology/approach The procedure for generation of the proposed OPENN predictive model was performed in two stages. In the first stage, as the high dimensionality involved in the input space, a correlation-based feature selection (CFS) algorithm was used to select the most important influencing variables for HGI prediction. In the second stage, a combination of differential evolution (DE) and biography-based optimization (BBO) algorithms as a global search method were applied to evolve weights of a multi-layer perception neural network. Findings The proposed OPENN was examined and compared with other typical models using a wide range of Kentucky coal samples. The testing results showed that the accuracy of the proposed OPENN model is significantly better than the other typical models and can be considered as a promising alternative for HGI prediction. Originality/value As HGI test is relatively expensive procedure, there is an economical interest on HGI modeling based on coal conventional properties (proximate, ultimate and petrography); the proposed OPENN model to estimate HGI would be a valuable and practical tool for coal industry.

scholarly journals Effects of Maturity of Coconut Shells on Gold Adsorption Efficiencies of Derived Activated Carbons

2019 ◽  
Vol 19 (2) ◽  
pp. 50-54
Author(s):  
W. K. Buah ◽  
J. Darmey ◽  
F. Osei
Keyword(s):  
Activated Carbon ◽  
Activated Carbons ◽  
Cyanide Solution ◽  
Adsorption Capacities ◽  
Relative Hardness ◽  
Coconut Shells ◽  
Activation Times ◽  
Adsorption Rates

AbstractCoconut shells are used as precursors for preparation of activated carbons. The shells could vary in terms of their maturity. The influence of the maturity of the shells on gold adsorption efficiencies of derived activated carbons (ACs) from gold di-cyanide solution was investigated. The shells were pyrolysed at 900 ºC and the resulting chars were activated in steam at the same temperature for different durations. Assessment of the properties of the derived ACs revealed that; the hardness, gold adsorption capacities and rates of gold adsorption of the ACs depended on the maturity of the shells. The more matured the shells the harder the AC. The relative hardness and gold adsorption rates of the mature coconut shells activated carbons, HMand RM, respectively and those of the less mature shells, HLand RL, respectively were in the order of HM >HL and RM >RL. The relative hardness of the ACs derived from the more mature and less mature shells after 3 hrs activation were 99.3% and 94.0%, respectively and the gold adsorption rates were 5.78 mg Au/hr/gand 4.95 mg Au/hr/g, respectively. The adsorption rates and relative hardness depended on the duration of activation, where longer activation times resulted in increase in the adsorption rates and a decrease in relative hardness of the derived ACs. Keywords: Adsorption, Activated Carbon, Coconut Shells, Maturity, Relative Hardness

The Analysis of Finishing Tooling Influence on Contact Fatigue Researched by Profilometer

2013 ◽  
Vol 199 ◽  
pp. 117-122
Author(s):  
Wojciech Labuda ◽  
Adam Charchalis
Keyword(s):  
Surface Roughness ◽  
Surface Layer ◽  
Contact Fatigue ◽  
Roughness Coefficient ◽  
304L Stainless Steel ◽  
Technological Parameters ◽  
Research Results ◽  
Burnishing Process ◽  
Relative Hardness ◽  
Surface Layer Quality

The article presents the research results referring to the analysis of the influence of finish treatment ( lathing, grinding, burnishing) on the contact fatigue of steel applied to marine pump shafts. The research was performed on a roller 40 mm in diameter made of 304L stainless steel. Within the research, the optimalization of burnishing technological parameters was conducted on account of the minimalization of Ra surface roughness coefficient as well as the maximalization of SU degree of surface layer relative hardness [. The multi criteria optimalization conducted by min-max method [ with regard to minimum surface roughness as well as maximum degree of surface layer hardness demonstrated that burnishing process should be carried out at the following technological parameters: burnishing force 1.1 kN, burnishing speed 35 m/min, feed 0.13 mm/rev. In addition, the influence of the burnisher passes number on the surface layer quality was determined [.The paper will present the research results of contact fatigue examination of samples after finish machining.

scholarly journals The integument and moult cycle of Tegenaria atrica (Araneae)

1942 ◽  
Vol 131 (862) ◽  
pp. 65-86 ◽  
Keyword(s):  
Molecular Structure ◽  
Blood Pressure ◽  
Blood Cell ◽  
Blood Cells ◽  
Alimentary Canal ◽  
Moult Cycle ◽  
Total Blood ◽  
Large Vacuole ◽  
Relative Hardness ◽  
Moulting Hormone

The integument of Tegenaria atrica consists of two chitinous layers, an outer exocuticula and an inner endocuticula. The former is impregnated with protein and pigment and may be birefringent. Its thickness and development of birefringence is related to the hardness of each region. The exocuticula is formed before, and the endocuticula after, the moult. The hypodermis appears to secrete the chitin of both layers. The substances impregnating the exocuticula are probably brought to it by granular blood cells. These granulocytes remain in the hypodermis after the moult. The granulocytes responsible for the exocuticular secretion at the last moult migrate on to the old integument as this separates from the hypodermis at the next one. An ecdysial fluid is present and is absorbed by the time of the actual moult but very little digestion of the old integument occurs. The chromatin of the hypodermal nuclei increases in amount up to the beginning of the secretion of the new integument. It then sharply decreases until after the moult, when the cycle is resumed. There are three types of blood cell—granulocytes, leucocytes, and leberidocytes. The latter have a single large vacuole and are formed from the leucocytes. They only appear in relation to the moult, forming 65 % of the total blood cells immediately after it. The digestive diverticula secrete a fluid which fills most of the alimentary canal at the time of the moult. The above results are discussed. There is evidence that the relative hardness of the exocuticula is due to both impregnation with proteins and phenols and to changes of molecular structure. It is suggested that the leberidocytes absorb water from the food, via the plasma, to increase the blood pressure for moulting and subsequent enlargement of the animal. The filling of the alimentary canal with fluid is associated with this. The possible origin of a moulting hormone is considered.

Strengthening Mechanisms and Tribological Properties of Ultra-Hard AlMgB14 Based Composite Reinforced with TiB2

2020 ◽  
Vol 12 (6) ◽  
pp. 866-872
Author(s):  
Wen Liu ◽  
Chun-Yan Hao ◽  
Xu-Dong Zhao ◽  
Xiang-Jun Wang ◽  
Guo-Liang Shi
Keyword(s):  
Fracture Toughness ◽  
Friction And Wear ◽  
Room Temperature ◽  
High Strength ◽  
Strengthening Mechanisms ◽  
Interface Bonding ◽  
Dispersion Strengthening ◽  
Hard Phase ◽  
Phase Dispersion ◽  
Relative Hardness

AlMgB14–TiB2 composites with ideal structures are successfully prepared by field activated and pressure assisted synthesis. The effects of different TiB2 contents on the relative hardness and toughness of the composites were investigated. The results showed adding TiB2 could both increase the hardness of AlMgB14 and improve the fracture toughness. The TiB2 contributed more to the hardness than to the toughness. The microstructure analysis shows that the main toughening mechanisms of AlMgB14–TiB2 composites are hard phase dispersion strengthening, high-strength interface bonding and the high elastic modulus of TiB2. Therefore, reducing the particle size of TiB2 to nanoscale is an efficient way to improve the toughness and hardness. The results of friction and wear experiment at room temperature have shown that the addition of TiB2 into AlMgB14 enhances the abrasion–resistant property.

Sign in / Sign up

Export Citation Format

Share Document