Bilal Haider, Shuhaimi Mansor, Shabudin Mat and Nazri Nasir
The flow topology for multi-disciplinary configuration (MULDICON) wing is very complicated and nonlinear at low to high angle of attack (AOA). This paper aims to provide the…
Abstract
Purpose
The flow topology for multi-disciplinary configuration (MULDICON) wing is very complicated and nonlinear at low to high angle of attack (AOA). This paper aims to provide the correlation between the unsteadiness and uncertainties of the flow topology and aerodynamic forces and moments above MULDICON WING at a medium to a higher AOA.
Design/methodology/approach
The experimental and computational fluid dynamics methods were used to investigate a generic MULDICON wing. During the experiment, the AOA were varied from α = 5° to 30°, whereas yaw angle varies between β = ±20° and Reynolds number between Re = 3.0 × 105 and Re = 4.50 × 105. During the experiments steady-state loading, dynamic loading and flow visualization wind tunnel methods were used.
Findings
The standard deviation quantified the unsteadiness and uncertainties of flow topology and predicted that they significantly affect the pitching moment (Cm) at medium to higher AOA. A strong correlation between flow topology and Cm was exhibited, and the experiment data was well validated by previous numerical work. The aerodynamic center was not fixed and shifted toward the wing apex when AOA is increasing. For a = 10°, the flow becomes more asymmetric. Power spectral densities plots quantify the flow separation (apex vortex, leading-edge vortex and vortex breakdown) over the MULDICON wing.
Originality/value
The application and comparison of steady-state and dynamic loading data to quantify the unsteadiness and uncertainties of flow topology above the MULDICON wing.
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P. Mamalis, A. Andreopoulos and N. Spyrellis
Some of the basic mechanical characteristics such as tensile, bending, shear, compression, and surface properties of cotton knitted fabrics after a durable flame‐retardant…
Abstract
Some of the basic mechanical characteristics such as tensile, bending, shear, compression, and surface properties of cotton knitted fabrics after a durable flame‐retardant finishing, were studied by the objective‐evaluation method developed by Kawabata and Niva using the KES‐F system. In addition, properties such as bursting strength, drape and sewability were studied in order to further explore the influence of this treatment on the fabrics. All treated fabrics were flame‐retardant but their mechanical properties showed changes as a result of the above finishing. More specifically, a significant reduction in the bending and shear properties was recorded, which suggests that the flame‐retardant finishing primarily affects the above characteristics.
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Siti Khumaira Mohd Jamari, Ramesh Kasi, Leeana Ismail, Nur Amirah Mat Nor, Ramis Rau Subramanian, T. Ramesh Subramaniam, Vengadaesvaran Balakrishnan and Abdul Kariem Mohd Arof
The purpose of this paper is to study the performance of coatings for corrosion protection. In this research, different compositions of polyaniline (PANI) were added in a…
Abstract
Purpose
The purpose of this paper is to study the performance of coatings for corrosion protection. In this research, different compositions of polyaniline (PANI) were added in a pigmented acrylic polyol-silicone coating. The important performance property is corrosion protection. The coatings must be evaluated under corrosive environment. Electrochemical impedance spectroscopy (EIS) is the suitable method to investigate the effect of the addition of PANI in the binder mixture.
Design/methodology/approach
The coating resistance, coating capacitance, water uptake and the diffusion coefficient of the coatings were tested for each of the sample. These parameters of the coatings were tested for a period of 60 days of exposure of 3.5 weight per cent solution of sodium chloride salt. EIS results will be further verified by immersion test and salt spray test.
Findings
Coating materials developed using 8 and 10 weight per cent of PANI exhibited better coating properties with higher coating resistance for a period 60 days immersion in corrosive environment compared to coatings with lower amount of PANI (2-6 weight per cent). The best coating system obtained the coating resistance value in the range of giga ohms even after the 60th day of exposure. The lowest capacitance value suggested that the coatings have not allowed the electrolyte to permeate to the interface. Water uptake values were found to be in the range of 5 per cent. Salt spray test results showed that the corrosion has initiated at the edges of the scratches only.
Practical implications
The study of the effect of conducting polymers in acrylic polyol/silicone resin hybrid binder will be useful for more exploration in coating science.
Originality/value
The development of protective hybrid coatings using conducting polymer and TiO2 particles is new. The results show high coating resistance values.
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Tourism and natural hazards share a long pathway, owing to the fragile existential status of certain tourist destinations and voluntary and involuntary intervention of mankind in…
Abstract
Tourism and natural hazards share a long pathway, owing to the fragile existential status of certain tourist destinations and voluntary and involuntary intervention of mankind in the business of natural environment. Over a course of history, numberless natural hazards prevailed and left behind some of the colossal and collateral damage on the physicality and virtuality of destinations. Volume of studies contended this direct and inverse association. Resultantly, impact measurement, ongoing imagery issues and future forecasting have been made to ease out the tourist destination from the consequences of natural hazards. Moreover, considering the inner fabric of tourism system (demand and supply side), natural hazards have been foreseen as unwanted yet necessary event to be emphasized and taken care of. Predominantly, in the existing global milieu of maximum human intervention in the climatic cycle and its outcomes in the form of global warming, climate concerns, natural hazards have been considered as inevitable and destined. Hence, it needs a comprehensive literature-based study to assess the risk factor of natural hazards on the tourist destinations. This study, in acquiescence to address this grey section, intends to explore the existing studies (drafted on the risks impacts of natural hazards on demand, supply and ancillary segments of tourism) and structure the findings thematically and orchestrate these findings in the existing body of literature. Implications from the findings have been presented.
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Anastasios G. Malliaris and Ramaprasad Bhar
The equity premium of the S&P 500 index is explained in this paper by several variables that can be grouped into fundamental, behavioral, and macroeconomic factors. We hypothesize…
Abstract
The equity premium of the S&P 500 index is explained in this paper by several variables that can be grouped into fundamental, behavioral, and macroeconomic factors. We hypothesize that the statistical significance of these variables changes across economic regimes. The three regimes we consider are the low‐volatility, medium‐volatility, and high‐volatility regimes in contrast to previous studies that do not differentiate across economic regimes. By using the three‐state Markov switching regime econometric methodology, we confirm that the statistical significance of the independent variables representing fundamentals, macroeconomic conditions, and a behavioral variable changes across economic regimes. Our findings offer an improved understanding of what moves the equity premium across economic regimes than what we can learn from single‐equation estimation. Our results also confirm the significance of momentum as a behavioral variable across all economic regimes
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Barileé B. Baridam and M. Montaz Ali
The K‐means clustering algorithm has been intensely researched owing to its simplicity of implementation and usefulness in the clustering task. However, there have also been…
Abstract
Purpose
The K‐means clustering algorithm has been intensely researched owing to its simplicity of implementation and usefulness in the clustering task. However, there have also been criticisms on its performance, in particular, for demanding the value of K before the actual clustering task. It is evident from previous researches that providing the number of clusters a priori does not in any way assist in the production of good quality clusters. The authors' investigations in this paper also confirm this finding. The purpose of this paper is to investigate further, the usefulness of the K‐means clustering in the clustering of high and multi‐dimensional data by applying it to biological sequence data.
Design/methodology/approach
The authors suggest a scheme which maps the high dimensional data into low dimensions, then show that the K‐means algorithm with pre‐processor produces good quality, compact and well‐separated clusters of the biological data mapped in low dimensions. For the purpose of clustering, a character‐to‐numeric conversion was conducted to transform the nucleic/amino acids symbols to numeric values.
Findings
A preprocessing technique has been suggested.
Originality/value
Conceptually this is a new paper with new results.
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Velmani M. and Suresh V.
This paper aims to numerically investigate the influence of shock wave and freestream turbulence interaction on the parabolic and spherically blunted nose cones at supersonic…
Abstract
Purpose
This paper aims to numerically investigate the influence of shock wave and freestream turbulence interaction on the parabolic and spherically blunted nose cones at supersonic speed.
Design/methodology/approach
Using density-based solver, the three-dimensional steady-state simulation is carried out. The working fluid is calorically perfect that obeys ideal gas law and the no-slip boundary conditionis given to the surface of the nose cone. Pressure far-field boundary condition is imposed at the boundary of the computational domain by giving freestream Mach number, freestream static pressure and temperature.
Findings
The growth rate of the boundary layer is faster on the spherically blunted nose cone, hence, the overall drag force is higher than the parabolic nose cone. Temperature at the edge of the boundary layer is increased due to the early ampli-fication of instabilities by the upstream disturbance. In this sense, the effects of freestream turbulence depend on its level, freestream conditions, strength and type of shock wave and zone of influence.
Research limitations/implications
Simulations are carried out for the flow Mach number 2.0 at zero angles of attack for the freestream conditions of the flow at an altitude of 10,000 m.
Practical implications
The phenomenon of shock wave–turbulence interaction occurs in flow regimes from transonic to hypersonic speeds and finds a wide range of applications, especially in the design of aircraft and missiles configurations.
Originality/value
The phenomenon of compression wave and freestream turbulence interaction around the commonly used nose cones in the case of aircraft, missiles, etc., is investigated. The performance characteristics such as aerodynamic drag, boundary layer dynamics and the nature of flow around the different nose cones at zero angle of attack are illustrated.
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Jacek Ptaszny and Marcin Hatłas
The purpose of this paper is to evaluate the efficiency of the fast multipole boundary element method (FMBEM) in the analysis of stress and effective properties of 3D linear…
Abstract
Purpose
The purpose of this paper is to evaluate the efficiency of the fast multipole boundary element method (FMBEM) in the analysis of stress and effective properties of 3D linear elastic structures with cavities. In particular, a comparison between the FMBEM and the finite element method (FEM) is performed in terms of accuracy, model size and computation time.
Design/methodology/approach
The developed FMBEM uses eight-node Serendipity boundary elements with numerical integration based on the adaptive subdivision of elements. Multipole and local expansions and translations involve solid harmonics. The proposed model is used to analyse a solid body with two interacting spherical cavities, and to predict the homogenized response of a porous material under linear displacement boundary condition. The FEM results are generated in commercial codes Ansys and MSC Patran/Nastran, and the results are compared in terms of accuracy, model size and execution time. Analytical solutions available in the literature are also considered.
Findings
FMBEM and FEM approximate the geometry with similar accuracy and provide similar results. However, FMBEM requires a model size that is smaller by an order of magnitude in terms of the number of degrees of freedom. The problems under consideration can be solved by using FMBEM within the time comparable to the FEM with an iterative solver.
Research limitations/implications
The present results are limited to linear elasticity.
Originality/value
This work is a step towards a comprehensive efficiency evaluation of the FMBEM applied to selected problems of micromechanics, by comparison with the commercial FEM codes.
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Irene Antonopoulos and Omar Madhloom
The global Clinical Legal Education (CLE) movement transcends borders as law teachers worldwide try to inculcate law students and future legal practitioners with social justice…
Abstract
The global Clinical Legal Education (CLE) movement transcends borders as law teachers worldwide try to inculcate law students and future legal practitioners with social justice values. One method of achieving this is through developing reflective practitioners. Kolb, finding common ground in the work of Lewin, Dewey, and Piaget, formulated the four stages in the experiential development of concrete experience, reflective observation, abstract conceptualization, and active experiment. Although Kolb’s model is used in legal education literature, students may not be provided with the relevant conceptual tools required to engage in reflective practice. This often results in students providing subjective analysis of their work, which fails to fully contribute to their educational experience. One of the reasons for omitting analytical tools is that reflective practice suffers from a lack of conceptual clarity. According to Kinsella, the “concept remains elusive, is open to multiple interpretations, and is applied in a myriad of ways in educational and practice environments”. A further issue hindering reflective practice relates to Donald Schön’s critique of the positivist approach adopted by law schools.
This chapter will apply a human rights framework to CLE to develop reflective practitioners. The two main reasons for this are, first, human rights as formulated by the Universal Declaration on Human Rights are universal, interrelated, and indivisible and, second, reflection based on these universal human rights values will benefit cross-jurisdictional societies in assisting vulnerable clients affected by emerging implied and direct human rights challenges.