Maximum Thickness Location Selection of High Subsonic Axial Compressor Airfoils and Its Effect on Aerodynamic Performance

Solidity and camber angle are key parameters with a primary effect on airfoil diffusion. Maximum thickness location has a considerable impact on blade loading distribution. This paper investigates correlations of maximum thickness location, solidity, and camber angle with airfoil performance to choose maximum thickness location quickly for compressor airfoils with different diffusion. The effects of maximum thickness location, solidity, and camber angle on incidence characteristics are discussed based on abundant two-dimensional cascade cases computed through numerical methods. Models of minimum loss incidence, total pressure loss coefficient, diffusion factor, and static pressure rise coefficient are established to describe correlations quantitatively. Based on models, dependence maps of total pressure loss coefficient, diffusion factor, and static pressure rise coefficient are drawn and total loss variation brought by maximum thickness location is analyzed. The study shows that the preferred selection of maximum thickness location can be the most forward one with no serious shock loss. Then, the choice maps of optimal maximum thickness location on different design conditions are presented. The optimal maximum thickness locates at 20–35% chord length. Finally, a database of optimal cases which can meet different loading requirements is provided as a tool for designers to choose geometrical parameters.

Influence of Nano-silica and Crack Width on Corrosion Parameters of Pre-cracked Reinforced Concrete Beams

This paper presents an experimental study on the durability of both sound and cracked reinforced concrete (RC) beam specimens. Using nano-silica (NS) can improve the durability properties of reinforced concrete. So, RC beams with three nano-silica percentages of 0 %, 1.5 %, and 3 % were prepared. In addition, to consider the effect of cracking on corrosion, crack widths between 0.1 mm and 0.5 mm, and cover depths of 30 mm and 45 mm were considered. All beam specimens were subjected to 5 % NaCl solution and monitored weekly for half-cell potentials (HCP). The presented results include the HCP evaluation and diffusion factor values in sound and cracked concrete beams exposed to chloride attack. The experimental results indicated that the chloride diffusion coefficient increases with extending crack width. Nano-silica improved the permeability characteristics of concrete, HCP and also diffusion factor values. Regressive models of the chloride diffusion factor and HCP values were proposed for influencing parameters, i.e., nano-silica and crack width with two different cover depths.

Kajian Resilience Sebagai Dampak Kebijakan Zonasi di Madrasah Ibtidaiyah

This study aims to examine resilience to the diffusion factor of innovation in Islamic education services (Madrasah Ibtidaiyah) on zoning policies that have a major impact on school sustainability in making strategies as educational institutions that are trusted by the community. This study uses a critical theory paradigm of a qualitative approach with descriptive methods. The research reports are responding to his resilience with a positive attitude with a luck risk, focus on core values, flexible, trying to achieve goals, dare to take concrete steps, create self-conditions and environments that support high expectations and expectations of teachers, students, people parents, as well as developing participatory attitudes and responsibilities.

The Effect of Trailing Edge Clearance in Suppressing Hub-Corner Stall

Hub corner is a high-loss area located within in the blade passages of turbomachinery. It is well known that flow separation and vortex development in this area directly affects, not only energy loss and efficiency, but also the stability of axial compressors. In this paper, a high diffusion factor cascade is used in order to analyze the vortex structure which causes the hub-corner stall in cascade. The trailing edge clearance method is proposed for controlling the hub-boundary layer and this is compared with full uniform clearance. Our research highlights that the trailing edge clearance suppress the radial development of the suction separation vortex (SSV) in the hub corner and restrains the concentrated separation vortex (CSV). The influence of trailing edge clearance parameters and its effect on control of hub-corner stall is discussed in detail. It is revealed that clearance height avoids flow separation and suppresses radial vortex development, while the clearance length resists the overturning that is caused by transverse pressure gradient and controls the development of CSV. As the radial vortex plays a dominant role in hub-corner stall, clearance height has a better effect in controlling hub-corner stall in comparison to length at the constant flow area.

Digital content as a fast Internet diffusion factor: Focusing on the fixed broadband Internet

The Internet has significantly changed the lifestyles of individuals and many aspects of society while also having an important effect on economic growth and sustainable development. However, the usage and diffusion of the Internet vary greatly depending on the country, considering their economic and social conditions. This study investigates through an empirical analysis the factors that make Internet diffusion faster, especially focusing on the digital content. The results show that the abundance of digital content has played a crucial role in the rapid diffusion of the Internet. At the diffusion take-off stage, the number of Internet users appears to be the most important factor for fast Internet diffusion. However, as diffusion progresses to a mature stage, the amount of available digital content becomes the crucial factor for fast Internet diffusion. Thus, the countries in which the Internet is less diffused and the economy is less developed also require policies that promote various digital content from the launching of the Internet service to anticipate fast Internet diffusion in the whole diffusion progress.

Hyperpolarised xenon magnetic resonance spectroscopy for the longitudinal assessment of changes in gas diffusion in IPF

Prognosticating idiopathic pulmonary fibrosis (IPF) is challenging, in part due to a lack of sensitive biomarkers. A recent article in Thorax described how hyperpolarised xenon magnetic resonance spectroscopy may quantify regional gas exchange in IPF lungs. In a population of patients with IPF, we find that the xenon signal from red blood cells diminishes relative to the tissue/plasma signal over a 12-month time period, even when the diffusion factor for carbon monoxide is static over the same time period. We conclude that hyperpolarised 129Xe MR spectroscopy may be sensitive to short-term changes in interstitial gas diffusion in IPF.

Characterization of Tandem Airfoil Configurations of Axial Compressors

The objective of the current study is to investigate the effects of geometric parameters on the fluid flow patterns, diffusion factor, load-split, and off-design performance of the tandem configuration under subsonic, rectilinear, cascade flow. A 2-D computational model using finite volume formulation has been developed and validated against available experimental data. The obtained data is presented in a format involving loss parameter and loading and will help the designer to have sufficient number of combinations within the useful range of application. It is observed that general performance behavior of tandem cascade is similar to a single airfoil data. Load shifting from the front airfoil to the rear airfoil is noted at positive axial overlaps and higher camber ratios. An optimum gap ratio of around 2 is observed for the range of configurations investigated. Contrary to the previous literature, the present study indicates higher loading of the front airfoil for the best overall loading-to-loss ratio of the tandem configuration.