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Before using basic oxygen furnace slag (BOFS) in any engineering application, it is important to determine its properties. The chemical composition, mineralogy, and physical properties of BOF slag are subject to large fluctuations as a result of different raw additives, different compositions of the molten iron used for producing the steel, oxygen stirring of a molten pool, uneven temperature fields, and other complex physical conditions. Thus, in this research, the engineering properties of BOF slag aggregates with different ages were identified, and then the feasibility of BOF slag aggregates in mortar application was investigated. It was found that stockpiled BOFS was harder than fresh BOF slag, which had lower aggregate crushing values and lower LA abrasion values. Also, stockpiled BOFS showed less expansion than fresh BOF slag regardless of water and 1 M NaOH solution immersion. The chemical reaction between f-CaO, f-MgO, and water due to weathering in the field extremely reduced the expansion of BOFS submerged in water. BOFS may contain reactive silica, which causes an alkali–silica reaction (ASR). Stockpiled BOFS (100%, 75%, 50%, 25%) used as a mineral filler in asphalt concrete mix brought about low tensile strength at break up (crack), low compressive strength at +50 °C, poor cohesion, and residual porosity. However, these parameters were partially improved with the use of a thermostable adhesive additive for road bitumen based on polyphosphoric acid esters. The comprehensive assessment in this study indicates that while some mixtures meet the specified criteria for certain properties, there are challenges, particularly regarding crack resistance and cohesion, that need to be addressed to fully align with the standard. Adjustments to the mixture proportions, the exploration of alternative additives, and the use of different types of fillers may be necessary to achieve the desired properties, especially in terms of crack resistance and cohesion. [ABSTRACT FROM AUTHOR]

Antireflection coatings (ARCs) with an indium thin oxide (ITO) layer on silicon heterojunction solar cells (SHJ) have garnered significant attention, which is due to their potential for increasing current density (Jsc) and enhancing reliability. We propose an additional tungsten trioxide (WO3) layer on the ITO/Si structure in this paper in order to raise the Jsc and demonstrate the influence on the SHJ solar cell. First, we simulate the Jsc characteristics for the proposed WO3/ITO/Si structure in order to analyze Jsc depending on the thickness of WO3 using an OPAL 2 simulator. As a result, the OPAL 2 simulation shows an increase in Jsc of 0.65 mA/cm2 after the 19 nm WO3 deposition on ITO with a doping concentration of 6.1 × 1020/cm2. We then fabricate the proposed samples and observe an improved efficiency of 0.5% with an increased Jsc of 0.75 mA/cm2 when using a 20 nm thick WO3 layer on the SHJ solar cell. The results indicate that the WO3 layer can be a candidate to improve the efficiency of SHJ solar cells with a low fabrication cost. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the effects of aluminum oxide (Al2O3) antireflection coating (ARC) on silicon heterojunction (SHJ) solar cells. Comprehensive ARCs simulation with Al2O3/ITO/c-Si structure is carried out and the feasibility to improve the short circuit current density (JSC) is demonstrated. Based on the simulation results, we apply Al2O3 ARC on SHJ solar cells, and the increasement in JSC to 1.5 mA/cm2 is observed with an Al2O3 layer thickness of 20 nm. It is because the total reflectance of SHJ solar cells is decreased by the shifting of the wavelength range on constructive and destructive light interference. As a result, we believe that the proposed Al2O3 ARC can support an effective engineering technic to increase JSC and efficiency of SHJ solar cells. [ABSTRACT FROM AUTHOR]

This paper presents the mechanical properties of silicate-grouted sands subjected to creep loadings at low stress levels. Uniaxial compressive tests were performed in order to determine the stress levels of constant creep tests. The uniaxial compressive strength rapidly increased with time over the first 7 days of curing and then approached a constant level. A series of creep tests were performed for three stress levels and viscoelastic theory was employed to assess the creep behavior. During the loading process elastic, plastic, and viscoelastic strains existed together. The recoverable portions contained elastic and time-dependent viscoelastic strains, and both were approximately linear. Test results showed that the magnitude of the instantaneous recoverable strains was independent of the unloading time. A constitutive model to predict the permanent deformation was developed. CE Database subject headings: Creep; Constitute models; Stress; Sand; Viscoelasticity.

In order to evaluate material characteristics (in situ modulus) of well-compacted subgrades, the portable falling weight deflectometer (PFWD) test, which simulates dynamic loads, was adopted. The falling energy was assumed as a dynamic load and a well-compacted subgrade was treated as an ideal elastic body. In addition, the static plate-bearing load test (PBLT) was used to evaluate the coefficient of subgrade reaction. The PFWD test and PBLT for a total of 22 testing points were carried out on well-compacted subgrades at two different highway construction sites (A and B). Three falling heights and weights were used to produce six different levels of dynamic loads. The test results show that there is a reasonable linear correlation between the dynamic deflection modulus and the coefficient of subgrade reaction of well-compacted subgrades. It was also found that the dynamic deflection modulus is not largely affected by variation of the falling energies. Application of the PFWD for compaction control and as an alternative method to the PBLT would lead to significant cost savings. DOI: 10.1061/(ASCE)0899-1561(2007)19:6(492) CE Database subject headings: Subgrades; Dynamic loads; Deflection; Elasticity; Compaction; Plates; Load tests.

The risk of a broad range of respiratory and heart diseases can be increased by widespread exposure to fine atmospheric particles on account of their capability to have a deep penetration into the blood streams and lung. Globally, studies conducted epidemiologically in Europe and elsewhere provided the evidence base indicating the major role of PM2.5 leading to more than four million deaths annually. Conventional approaches to simulate atmospheric transportation of particles having high dimensionality from both transport and chemical reaction process make exhaustive causal inference difficult. Alternative model reduction methods were adopted, specifically a data-driven directed graph representation, to deduce causal directionality and spatial embeddedness. An undirected correlation and a directed Granger causality network were established through utilizing PM2.5 concentrations in 14 United Kingdom cities for one year. To demonstrate both reduced-order cases, the United Kingdom was split up into two southern and northern connected city communities, with notable spatial embedding in summer and spring. It continued to reach stability to disturbances through the network trophic coherence parameter and by which winter was construed as the most considerable vulnerability. Thanks to our novel graph reduced modeling, we could represent high-dimensional knowledge in a causal inference and stability framework. [ABSTRACT FROM AUTHOR]

It is common to increase road capacity by constructing ring roads to reduce traffic congestion in city areas, although this is often found to be ineffective in the long run. Accordingly, this study investigates various traffic congestion management approaches and their effectiveness in major cities, and explores an identical transport problem in Almaty, Kazakhstan: The Big Almaty Ring Road (BAKAD). Several case examples from the existing literature are examined in which various approaches were taken for managing traffic congestion problems, and these approaches are classified into three concepts. The first concept comprises heavy engineering measures such as ring road development, new road construction, expansion of existing roads, etc. Such measures can initially reduce traffic congestion, but often become ineffective with time due to the generation of induced traffic. Many cities have taken Push and Pull measures that ensure more efficient use of existing capacity and have initiated environmentally friendly alternative transportation modes such as decreased car usage; promotion of public transport, biking and walking; minimization of the necessity of people's movement by changing urban land use patterns; and so on. These approaches have been found to be effective in providing sustainable transportation solutions and are classified as concept 2. Nevertheless, Push and Pull measures might not be enough for managing traffic congestion, and it might be necessary to increase the road capacity through heavy engineering measures, especially if the city experiences heavy transit traffic. This combined approach is categorized as concept 3. Consequently, the BAKAD project is examined under the umbrella of three concepts, and recommendations are provided based on the findings from the experience of different cities and interviews with experts from Almaty city. Both the results and recommendations developed are relevant for this specific case only, and are not necessarily transferable. [ABSTRACT FROM AUTHOR]