Structure Development and Deformation Behaviour of Pure Aluminium Processed by Constrained Groove Pressing

2014 ◽  
Vol 794-796 ◽  
pp. 882-887
Author(s):  
Jozef Zrník ◽  
Miroslav Cieslar ◽  
Peter Slama
Keyword(s):  
Tensile Strength ◽  
Deformation Behaviour ◽  
Electron Back Scatter Diffraction ◽  
Pure Aluminium ◽  
Deformation Method ◽  
Substantial Impact ◽  
Thin Foils ◽  
Commercial Purity Aluminium ◽  
Deformation Step ◽  
The Impact

In this study, the relationship between the structure and properties of commercial purity aluminium alloy A1199 was investigated by applying constrained groove pressing (CGP) deformation method. The refinement of the coarse grain aluminium (Al) microstructure to sub microcrystalline size by large plastic strain at room temperature defined. The impact of various strains upon microstructure changes is investigated using transmission electron microscopy (TEM of thin foils) and electron back scatter diffraction (EBSD). A mixture of subgrains produced by grains subdivision and polygonized subgrains formed locally due to dynamic recovery was found in the deformed aluminium structure. The tensile properties and resulting hardness are related to microstructural evolution induced by constrained groove pressing deformation. A substantial impact of straining upon the increasing in tensile strength was observed after the first deformation step (first pass) Further strain increase had an insignificant effect on tensile strength but was accompanied by ductility loss. The post deformation annealing effect was then explored with aim to increase the ductility. The results indicate that changes in strength and ductility may be related to formation of a bimodal structure in deformed plates.

Microstructure and Properties of Aluminium Processed by Constrained Groove Pressing

2008 ◽  
Vol 584-586 ◽  
pp. 535-540 ◽  
Author(s):  
Jozef Zrník ◽  
Tomas Kovarik ◽  
Miroslav Cieslar
Keyword(s):  
Tensile Strength ◽  
Electron Back Scatter Diffraction ◽  
Substantial Impact ◽  
Transmission Electron ◽  
Purity Aluminium ◽  
Commercial Purity Aluminium ◽  
The Impact ◽  
The Relationship ◽  
Strength And Ductility ◽  
Strain Increase

In this study, the relationship between the structure and properties of commercial purity aluminium (AW-1199) was investigated by applying constrained groove pressing (CGP) method. The refinement of the coarse grain aluminium microstructure to submicrocrystalline size by large plastic strain at room temperature defined. The impact of various strains upon microstructure changes is investigated using transmission electron microscopy (TEM) and electron back scatter diffraction (EBSD). A mixture of subgrains produced by grains subdivision and polygonized subgrains formed locally due to dynamic recovery was found in the deformed aluminium. The tensile properties and resulting hardness are related to microstructural evolution induced by CGP. A substantial impact of straining upon the increasing in tensile strength was observed after the first pass. Further strain increase had an insignificant effect on tensile strength but was accompanied by ductility loss. The post deformation annealing effect was then explored with aim to increase the ductility. The results indicate that changes in strength and ductility may be related to formation of a bimodal structure.

Investigations of size effect on formability and microstructure evolution in SS304 thin foils

2018 ◽  
Vol 53 (7) ◽  
pp. 517-528
Author(s):  
Jambeswar Sahu ◽  
Shanta Chakrabarty ◽  
Rajesh Raghavan ◽  
Sushil Mishra
Keyword(s):  
Microstructure Evolution ◽  
Mechanical Response ◽  
Deformation Behaviour ◽  
Sheet Material ◽  
Foil Thickness ◽  
Dome Height ◽  
Forming Process ◽  
Thin Foils ◽  
Grain Misorientation ◽  
The Impact

In the micro-forming process when the thickness of the sheet material is comparable to the intrinsic length scales of that material, deformation behaviour differs from that which is expected in the macroscopic sheet material. In this study, size effects of SS304 foils have been investigated using tensile and limiting dome height tests along with careful microstructural investigations. SS304 foils of differing thicknesses but similar grain size have been deformed under varying strain path conditions to capture the impact of foil thickness on the mechanical response and microstructure evolution. Formability curves for SS304 foils constructed from limiting dome height tests show that limit strains increase with increasing foil thickness. Microstructure investigations highlight the importance of grain misorientation, twin fraction and texture on the formability of SS304 foils.

Effect of combined drink cans and steel fibers on the impact resistance and mechanical properties of concrete

2020 ◽  
Vol 14 (2) ◽  
pp. 6734-6742
Author(s):  
A. Syamsir ◽  
S. M. Mubin ◽  
N. M. Nor ◽  
V. Anggraini ◽  
S. Nagappan ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Compressive Strength ◽  
Reinforced Concrete ◽  
Impact Resistance ◽  
Fiber Reinforced Concrete ◽  
Steel Fibers ◽  
Fiber Reinforced ◽  
Indirect Tensile ◽  
The Impact

This study investigated the combine effect of 0.2 % drink cans and steel fibers with volume fractions of 0%, 0.5%, 1%, 1.5%, 2%, 2.5% and 3% to the mechanical properties and impact resistance of concrete. Hooked-end steel fiber with 30 mm and 0.75 mm length and diameter, respectively was selected for this study.  The drinks cans fiber were twisted manually in order to increase friction between fiber and concrete. The results of the experiment showed that the combination of steel fibers and drink cans fibers improved the strength performance of concrete, especially the compressive strength, flexural strength and indirect tensile strength. The results of the experiment showed that the combination of steel fibers and drink cans fibers improved the compressive strength, flexural strength and indirect tensile strength by 2.3, 7, and 2 times as compare to batch 1, respectively. Moreover, the impact resistance of fiber reinforced concrete has increase by 7 times as compared to non-fiber concretes. Moreover, the impact resistance of fiber reinforced concrete consistently gave better results as compared to non-fiber concretes. The fiber reinforced concrete turned more ductile as the dosage of fibers was increased and ductility started to decrease slightly after optimum fiber dosage was reached. It was found that concrete with combination of 2% steel and 0.2% drink cans fibers showed the highest compressive, split tensile, flexural as well as impact strength.    

The Digital Divide and K-12 Student Computer Use

10.28945/2926 ◽  
2005 ◽  
Author(s):  
James N. Morgan ◽  
Craig A. VanLengen
Keyword(s):  
Digital Divide ◽  
Computer Use ◽  
Census Data ◽  
Internet Access ◽  
Demographic Characteristics ◽  
The Internet ◽  
Substantial Impact ◽  
Limited Basis ◽  
K 12 ◽  
The Impact

The divide between those who have computer and Internet access and those who do not appears to be narrowing, however overall statistics may be misleading. Measures of computer availability in schools often include cases where computers are only available for administration or are available only on a very limited basis (Gootman, 2004). Access to a computer and the Internet outside of school helps to reinforce student learning and emphasize the importance of using technology. Recent U.S. statistics indicate that ethnic background and other demographic characteristics still have substantial impact on the availability and use of computers by students outside of the classroom. This paper examines recent census data to determine the impact of the household on student computer use outside of the classroom. Encouragingly, the findings of this study suggest that use of a computer at school substantially increases the chance that a student will use a computer outside of class. Additionally, this study suggests that computer use outside of the classroom is positively and significantly impacted by being in a household with adults who either use a computer at work or work in an industry where computers are extensively used.

scholarly journals Evaluation of the Impact of Organic Fillers on Selected Properties of Organosilicon Polymer

Polymers ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1103
Author(s):  
Sara Sarraj ◽  
Małgorzata Szymiczek ◽  
Tomasz Machoczek ◽  
Maciej Mrówka
Keyword(s):  
Tensile Strength ◽  
Natural Fiber ◽  
Accelerated Aging ◽  
Strength Properties ◽  
Visual Observation ◽  
Walnut Shell ◽  
Pistachio Shell ◽  
Thermoplastic Matrix ◽  
Static Tensile ◽  
The Impact

Eco-friendly composites are proposed to substitute commonly available polymers. Currently, wood–plastic composites and natural fiber-reinforced composites are gaining growing recognition in the industry, being mostly on the thermoplastic matrix. However, little data are available about the possibility of producing biocomposites on a silicone matrix. This study focused on assessing selected organic fillers’ impact (ground coffee waste (GCW), walnut shell (WS), brewers’ spent grains (BSG), pistachio shell (PS), and chestnut (CH)) on the physicochemical and mechanical properties of silicone-based materials. Density, hardness, rebound resilience, and static tensile strength of the obtained composites were tested, as well as the effect of accelerated aging under artificial seawater conditions. The results revealed changes in the material’s properties (minimal density changes, hardness variation, overall decreasing resilience, and decreased tensile strength properties). The aging test revealed certain bioactivities of the obtained composites. The degree of material degradation was assessed on the basis of the strength characteristics and visual observation. The investigation carried out indicated the impact of the filler’s type, chemical composition, and grain size on the obtained materials’ properties and shed light on the possibility of acquiring ecological silicone-based materials.

scholarly journals Review on Urban Heat Island in China: Methods, Its Impact on Buildings Energy Demand and Mitigation Strategies

2021 ◽  
Vol 13 (2) ◽  
pp. 762
Author(s):  
Liu Tian ◽  
Yongcai Li ◽  
Jun Lu ◽  
Jue Wang
Keyword(s):  
Energy Consumption ◽  
Urban Heat Island ◽  
Building Energy ◽  
Design Stage ◽  
Heat Island ◽  
Building Energy Consumption ◽  
Rapid Urbanization ◽  
Substantial Impact ◽  
Urban Heat ◽  
The Impact

High population density, dense high-rise buildings, and impervious pavements increase the vulnerability of cities, which aggravate the urban climate environment characterized by the urban heat island (UHI) effect. Cities in China provide unique information on the UHI phenomenon because they have experienced rapid urbanization and dramatic economic development, which have had a great influence on the climate in recent decades. This paper provides a review of recent research on the methods and impacts of UHI on building energy consumption, and the practical techniques that can be used to mitigate the adverse effects of UHI in China. The impact of UHI on building energy consumption depends largely on the local microclimate, the urban area features where the building is located, and the type and characteristics of the building. In the urban areas dominated by air conditioning, UHI could result in an approximately 10–16% increase in cooling energy consumption. Besides, the potential negative effects of UHI can be prevented from China in many ways, such as urban greening, cool material, water bodies, urban ventilation, etc. These strategies could have a substantial impact on the overall urban thermal environment if they can be used in the project design stage of urban planning and implemented on a large scale. Therefore, this study is useful to deepen the understanding of the physical mechanisms of UHI and provide practical approaches to fight the UHI for the urban planners, public health officials, and city decision-makers in China.

scholarly journals Damage Evolution of Granodiorite after Heating and Cooling Treatments

Minerals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 779
Author(s):  
Mohamed Gomah ◽  
Guichen Li ◽  
Salah Bader ◽  
Mohamed Elkarmoty ◽  
Mohamed Ismael
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Failure Mode ◽  
Physical And Mechanical Properties ◽  
P Wave ◽  
Physical Parameters ◽  
Slow Cooling ◽  
Heating And Cooling ◽  
Natural Rock ◽  
The Impact

The awareness of the impact of high temperatures on rock properties is essential to the design of deep geotechnical applications. The purpose of this research is to assess the influence of heating and cooling treatments on the physical and mechanical properties of Egyptian granodiorite as a degrading factor. The samples were heated to various temperatures (200, 400, 600, and 800 °C) and then cooled at different rates, either slowly cooled in the oven and air or quickly cooled in water. The porosity, water absorption, P-wave velocity, tensile strength, failure mode, and associated microstructural alterations due to thermal effect have been studied. The study revealed that the granodiorite has a slight drop in tensile strength, up to 400 °C, for slow cooling routes and that most of the physical attributes are comparable to natural rock. Despite this, granodiorite thermal deterioration is substantially higher for quick cooling than for slow cooling. Between 400:600 °C is ‘the transitional stage’, where the physical and mechanical characteristics degraded exponentially for all cooling pathways. Independent of the cooling method, the granodiorite showed a ductile failure mode associated with reduced peak tensile strengths. Additionally, the microstructure altered from predominantly intergranular cracking to more trans-granular cracking at 600 °C. The integrity of the granodiorite structure was compromised at 800 °C, the physical parameters deteriorated, and the rock tensile strength was negligible. In this research, the temperatures of 400, 600, and 800 °C were remarked to be typical of three divergent phases of granodiorite mechanical and physical properties evolution. Furthermore, 400 °C could be considered as the threshold limit for Egyptian granodiorite physical and mechanical properties for typical thermal underground applications.

scholarly journals The Impact of the Coronavirus Disease (COVID-19) on the Health and Social Needs of Sex Workers in Singapore

2021 ◽  
Author(s):  
Rayner Kay Jin Tan ◽  
Vanessa Ho ◽  
Sherry Sherqueshaa ◽  
Wany Dee ◽  
Jane Mingjie Lim ◽  
...  
Keyword(s):  
Food Insecurity ◽  
Sex Work ◽  
Sex Workers ◽  
Social Needs ◽  
Medical Services ◽  
Substantial Impact ◽  
Sex Worker ◽  
Permanent Resident ◽  
The Impact ◽  
Depth Interviews

AbstractWe evaluated the impact of the coronavirus disease (COVID-19) on the sex work industry and assessed how it has impacted the health and social conditions of sex workers in Singapore. We conducted a sequential exploratory mixed methods study amidst the COVID-19 pandemic from April to October 2020, including in-depth interviews with 24 stakeholders from the sex work industry and surveyor-administered structured surveys with 171 sex workers. COVID-19 had a substantial impact on sex workers' income. The illegality of sex work, stigma, and the lack of work documentation were cited as exclusionary factors for access to alternative jobs or government relief. Sex workers had experienced an increase in food insecurity (57.3%), housing insecurity (32.8%), and sexual compromise (8.2%), as well as a decrease in access to medical services (16.4%). Being transgender female was positively associated with increased food insecurity (aPR = 1.23, 95% CI [1.08, 1.41]), housing insecurity (aPR = 1.28, 95% CI [1.03, 1.60]), and decreased access to medical services (aPR = 1.74, 95% CI [1.23, 2.46]); being a venue-based sex worker was positively associated with increased food insecurity (aPR = 1.46, 95% CI [1.00, 2.13]), and being a non-Singaporean citizen or permanent resident was positively associated with increased housing insecurity (aPR = 2.59, 95% CI [1.73, 3.85]). Our findings suggest that COVID-19 has led to a loss of income for sex workers, greater food and housing insecurity, increased sexual compromise, and reduced access to medical services for sex workers. A lack of access to government relief among sex workers exacerbated such conditions. Efforts to address such population health inequities should be implemented.

scholarly journals Laboratory Study of Deformation Behaviour of Two New Reinforcing Polymeric TSLs and Their Potential Application in Deep Underground Coal Mine

Polymers ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 2205
Author(s):  
Han Liang ◽  
Jun Han ◽  
Chen Cao ◽  
Shuangwen Ma
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Underground Mining ◽  
Deformation Behaviour ◽  
Polymer Materials ◽  
Surface Protection ◽  
Steel Mesh ◽  
Geological Conditions ◽  
Deep Underground ◽  
Roadway Support

Thin spray-on liner (TSL) is a surface protection technology used by spraying a polymer film, which is widely used for mine airtightness and waterproofing. A reinforcing TSL can replace steel mesh, which is a new method for roadway support. This paper reviews the development of a reinforcing TSL. Considering the deterioration of geological conditions in deep underground mining and the demand for reinforcing automation, two kinds of polymeric reinforcing TSL (RPTSL) materials are developed. The mechanical characteristics of the new TSL materials are studied experimentally. Results show that the average compressive strength, tensile strength, cohesion, and internal friction angle of the two TSL materials are 52 and 32 MPa, 12 and 8 MPa, 6.2 and 17.2 MPa, and 33.6° and 25.9°, respectively. The bonding strength between the two materials and coal is greater than the tensile strength of coal itself, and the mechanical properties of the material for comparison are lower than those of both materials. Based on the TSL support mechanism, we examine the application of the two TSL materials to the mining environment and compare the mechanical properties of polymer materials and cement-based materials. The advantages of polymer materials include versatile mechanical properties, good adhesion, and high early strength. This study provides a new support material to replace steel mesh for roadway surface support, which satisfies the needs of different surface support designs under complex geological conditions, and promotes the automation of roadway support.

scholarly journals Use of Artificial Intelligence to understand adults’ thoughts and behaviours relating to COVID-19

2021 ◽  
pp. 175791392097933
Author(s):  
SW Flint ◽  
A Piotrkowicz ◽  
K Watts
Keyword(s):  
Artificial Intelligence ◽  
Online Survey ◽  
Severe Illness ◽  
Free Text ◽  
Community Recovery ◽  
Substantial Impact ◽  
Lifestyle Behaviours ◽  
Artificial Intelligence Methods ◽  
High Concern ◽  
The Impact

Aims: The outbreak of severe acute respiratory syndrome coronavirus 2 (COVID-19) is a global pandemic that has had substantial impact across societies. An attempt to reduce infection and spread of the disease, for most nations, has led to a lockdown period, where people’s movement has been restricted resulting in a consequential impact on employment, lifestyle behaviours and wellbeing. As such, this study aimed to explore adults’ thoughts and behaviours in response to the outbreak and resulting lockdown measures. Methods: Using an online survey, 1126 adults responded to invitations to participate in the study. Participants, all aged 18 years or older, were recruited using social media, email distribution lists, website advertisement and word of mouth. Sentiment and personality features extracted from free-text responses using Artificial Intelligence methods were used to cluster participants. Results: Findings demonstrated that there was varied knowledge of the symptoms of COVID-19 and high concern about infection, severe illness and death, spread to others, the impact on the health service and on the economy. Higher concerns about infection, illness and death were reported by people identified at high risk of severe illness from COVID-19. Behavioural clusters, identified using Artificial Intelligence methods, differed significantly in sentiment and personality traits, as well as concerns about COVID-19, actions, lifestyle behaviours and wellbeing during the COVID-19 lockdown. Conclusions: This time-sensitive study provides important insights into adults’ perceptions and behaviours in response to the COVID-19 pandemic and associated lockdown. The use of Artificial Intelligence has identified that there are two behavioural clusters that can predict people’s responses during the COVID-19 pandemic, which goes beyond simple demographic groupings. Considering these insights may improve the effectiveness of communication, actions to reduce the direct and indirect impact of the COVID-19 pandemic and to support community recovery.

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