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In object segmentation, the existence of hard-classified-pixels limits the segmentation performance. Focusing on these hard pixels through assigning different weights to pixel loss can guide the learning of segmentation model effectively. Existing loss weight assignment methods perceive pixels hardness by current predicted information, pay less attention to past predicted information. While current studies show that samples with less improvement in predicted probability compared to the past are difficult to learn. To define hard pixels more accurately, a hardness-aware loss for object segmentation is proposed. Firstly, the metric of pixel hardness degree is defined, and a mapping function is proposed to quantitatively evaluate the hardness degree which is defined on the difference between current and past predicted probabilities. Then a new compound metric, hardness value, is defined based on hardness degree and the uncertainty. Based on the compound metric, a new loss function is proposed. Experiment results on four datasets using convolutional neural network and Transformer as the backbone models demonstrate that the proposed method effectively improves the accuracy of object segmentation. Especially, in the segmentation model based on ResNet-50, the proposed method improves mean Intersection over Union (mIoU) by almost 4.3 % compared to cross entropy on DUT-O dataset. [ABSTRACT FROM AUTHOR]

In object segmentation, the existence of hard-classified-pixels limits the segmentation performance. Focusing on these hard pixels through assigning different weights to pixel loss can guide the learning of segmentation model effectively. Existing loss weight assignment methods perceive pixels hardness by current predicted information, pay less attention to past predicted information. While current studies show that samples with less improvement in predicted probability compared to the past are difficult to learn. To define hard pixels more accurately, a hardness-aware loss for object segmentation is proposed. Firstly, the metric of pixel hardness degree is defined, and a mapping function is proposed to quantitatively evaluate the hardness degree which is defined on the difference between current and past predicted probabilities. Then a new compound metric, hardness value, is defined based on hardness degree and the uncertainty. Based on the compound metric, a new loss function is proposed. Experiment results on four datasets using convolutional neural network and Transformer as the backbone models demonstrate that the proposed method effectively improves the accuracy of object segmentation. Especially, in the segmentation model based on ResNet-50, the proposed method improves mean Intersection over Union (mIoU) by almost 4.3 % compared to cross entropy on DUT-O dataset.

P91 and P92 steels are widely used in nuclear and thermal power plant's high-temperature (650–700 °C) operating components. The welding procedure, base plate composition, filler material composition, and post-weld heat treatment (PWHT) significantly affect the metallurgical characterization of weldments at room temperature. This work focuses on joining P91 and P92 steel by the TIG welding with filler ER90S-B9. The study analyzes the materialization of coarse-grained HAZ (CGHAZ), inter-critical HAZ (ICHAZ), and fine grained HAZ (FGHAZ) under welded and PWHT. PWHT was conducted at 840 °C for 2, 4 and 6h. An optical microscopic (OM) scanning electron microscope (SEM) was employed to characterize the welded and PWHT samples. It was perceived that the tensile strength of PWHT increased as the heat treatment times increased from 2 to 6 h, while the hardness value decreased accordingly. The maximum tensile strength (594.71 MPa) was observed in PWHT_6 h, while the minimum tensile strength (537.52 MPa) was perceived in the as-welded sample. The PWHT_6h reveals the minimum hardness values (271.12 HV) at the fusion zone among all the conditions. The WFZ consisted of an untampered lath martensitic grain structure, demonstrating an average hardness value of 314.15 HV in the PWHT_2h condition. The hardness value in CGHAZ samples for as-welded, PWHT_2h, PWHT_4h, and PWHT_6h was observed at 456.85, 436.81, 368.63, and 327.41 HV, respectively. [ABSTRACT FROM AUTHOR]

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The problems faced are aluminum (Al) waste from industries that damage the environment and scarcity of Al raw materials that need to be recycled from used Al. The research objective was to determine the effect of adding magnesium (Mg) to used Al casting on the tensile strength and microstructure and to determine the comparison of the tensile strength of the Al material used by the piston to the brake lining and drum of motorcycles. The research method includes casting Al used pistons, brake lining and drum, testing the tensile strength and microstructure due to the addition of 0.1; 0.2; 0.5 and 1.0% by weight Mg to the tensile strength and microstructure. The results showed that the addition of Mg 0.5% by weight could increase the tensile strength of 92.96% from 71 MPa to 137 MPa for brake lining as the optimum value which further decreased the tensile strength by 19.7% at the addition of 1% Mg to 110 MPa. Drum material also experienced an increase in tensile strength of 33.71% from 89 MPa to 119 MPa as the optimum value where the tensile strength decreased by 5.88% for the addition of 1% Mg to 112 MPa. The two values of the tensile strength of the brake lining and drum components are lower than those of the piston component valued at 147 MPa, and with the addition of Mg, Mg2Si is formed which can reduce the porosity of the microstructure, thereby increasing its strength.

This article identifies factors influencing hardenability of steels in manufacturing conditions of OJSC « BSW – Management Company of Holding «BMC». The article contains results of a study on dependence of hardenability of steel grade 42CrMoS4 on design features of the equipment and the process aimed to ensure correspondence of the fi al product to the requirements. Measures that minimize spread of values due to preparation of samples for hardenability test in industrial conditions are presented. When predicting hardenability band, it is necessary implement a package of application programs that consider influence of factors existing in the conditions of a particular steel manufacturer.

Copyright of Journal of Petroleum Research & Studies is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract - The effect of age hardening heat treatment on the hardness values of 93.95Al-5Zn-1.05Sn/5Al2O3-SiO2 particulate composite has been studied. The data used for the work was generated at the National Metallurgical Development Centre, Jos Foundry shop, where the composite was developed. The composite was developed using the stir cast method. The result of the work has shown that the composite has a response to age hardening heat treatment with the optimum hardness value occurring at 2 hours of age hardening. A model was developed for the relationship between age hardening time and hardness of the composite. It was tested, and the product moment of correlation and the coefficient of correlation values attested to the degree of correlation existing between the two variables.

The effect of age hardening heat treatment on the hardness values of 93.95Al-5Zn-1.05Sn /5Al2O3-SiO2 particulate composite has been studied. The data used for the work was generated at the National Metallurgical Development Centre, Jos Foundry shop, where the composite was developed. The composite was developed using the stir cast method. The result of the work has shown that the composite has a response to age hardening heat treatment with the optimum hardness value occurring at 2 hours of age hardening. A model was developed for the relationship between age hardening time and hardness of the composite. It was tested, and the product moment of correlation and the coefficient of correlation values attested to the degree of correlation existing between the two variables. [ABSTRACT FROM AUTHOR]

In an attempt to improve the wear resistance of a failed automobile brake disc, different type of heat treatment operation was carried out on the samples of the disc. The samples were heated to 840°C 860°C and 880°C in a muffle furnace, and quenched in water, palm oil and air, separately. Water and oil quenched samples were later tempered at 200°C. The chemical composition of the failed brake disc was obtained by an optical emission spectrometer (OES), while the hardness value was measured using Brinell hardness testing machine. The highest Brinell hardness value of 331 BHN was obtained from the water-quenched sample heated to 880°C. The hardness values of the oil-quenched samples surpass that of air-quenched samples. The tempered samples displayed lower hardness values compared with the hardened samples, although the sample heat treated at 880°C, water-quenched and tempered still possesses high hardness value. The reduction in hardness of most of the samples after tempering suggests possible increase in ductility and toughness. As a result of the heat treatment and subsequent quenching, the retained austenite in the samples transforms to martensite, while the ferrite, flakes of graphite, and cementite were restructured. This shows that the brake disc could be hardened and tempered to obtain optimum hardness with improved ductility and toughness. This will result in better wear resistance, increase service life, and thus reduce brake failure and other related transportation hazard. [ABSTRACT FROM AUTHOR]

Several wastes can be instrumental in the improvement of the mechanical properties of medium carbon steel when quenched. The quenching media employed such as coconut water (CW), pap water (PW) and spent engine oil (SPE) have been largely considered as wastes. The data in this article are related to the research article titled "Mechanical Properties Improvement Evaluation of Medium Carbon Steels Quenched in Different Media" (Ikubanni et al., 2017) [1]. The article provides information on the mechanical properties evaluation of medium carbon steel quenched in different media. Twenty-seven (27) samples of medium carbon steel samples were heated to temperatures of 730 °C, 760 °C and 790 °C and soaked for 30, 45 and 60 min respectively. The test results recorded include hardness value, yield strength (YS) and the ultimate tensile strength (UTS) for each of the samples at different heating temperatures and soaking time for the different quenching media.