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1 – 10 of 32M. Vishal and K.S. Satyanarayanan
This study delineates the effect of cover thickness on reinforced concrete (RC) columns and beams under an elevated fire scenario. Columns and beams are important load-carrying…
Abstract
Purpose
This study delineates the effect of cover thickness on reinforced concrete (RC) columns and beams under an elevated fire scenario. Columns and beams are important load-carrying structural members of buildings. Under all circumstances, the columns and beams were set to be free from damage to avoid structural failure. Under the high-temperature scenario, the RC element may fail because of the material deterioration that occurs owing to the thermal effect. This study attempts to determine the optimum cover thickness for beams and columns under extreme loads and fire conditions.
Design/methodology/approach
Cover thicknesses of 30, 40, 45, 50, 60 and 70 mm for the columns and 10, 20, 25, 30, 35, 40, 50, 60 and 70 mm for the beams were adopted in this study. Both steady-state and transient-state conditions under thermomechanical analysis were performed using the finite element method to determine the heat transfer through the RC section and to determine the effect of thermal stresses.
Findings
The results show that the RC elements have a greater influence on the additional cover thickness at extreme temperatures and higher load ratios than at the service stages. The safe limits of the structural members were obtained under the combined effects of elevated temperatures and structural loads. The results also indicate that the compression members have a better thermal performance than the flexural members.
Research limitations/implications
Numerical investigations concerning the high-temperature behavior of structural elements are useful. The lack of an experimental setup encourages researchers to perform numerical investigations. In this study, the finite element models were validated with existing finite element models and experimental results.
Practical implications
The obtained safe limit for the structural members could help to understand their resistance to fire in a real-time scenario. From the safe limit, a suitable design can be preferred while designing the structural members. This could probably save the structure from collapse.
Originality/value
There is a lack of both numerical and experimental research works. In numerical modeling, the research works found in the literature had difficulties in developing a numerical model that satisfactorily represents the structural members under fire, not being able to adequately understand their behavior at high temperatures. None of them considered the influence of the cover thickness under extreme fire and loading conditions. In this paper, this influence was evaluated and discussed.
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Some capital‐intensive manufacturing businesses pose particular problems to market planners because the profit margins are often highly cyclical as seller capacity utilisation…
Abstract
Some capital‐intensive manufacturing businesses pose particular problems to market planners because the profit margins are often highly cyclical as seller capacity utilisation changes through the four‐year business cycle and may also be heavily affected by new entrants on the seller side or the emergence of strong buyers. This article examines how margins are related to market structure for Strategic Business Units in the PIMS database. Having identified that margins are related to some descriptions of market structure, it explores how the margin behaviour of capital‐intensive businesses can be modelled as changes in the relative power of buyers and sellers as the capacity utilisation of the sellers changes.
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Abstract
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Chiranjeeva Rao Seela and Ravi Sankar B.
The purpose of this paper is to assess the influence of blends of Jatropha methyl ester (JME) and its nano Al2O3 emulsion on variable compression ratio diesel engine. The oxygen…
Abstract
Purpose
The purpose of this paper is to assess the influence of blends of Jatropha methyl ester (JME) and its nano Al2O3 emulsion on variable compression ratio diesel engine. The oxygen in alumina contributed for the smooth burning and resulted in improved performance and emissions.
Design/Methodology/Approach
The biodiesel (methyl ester) is prepared from the raw Jatropha oil. The B10, B20 and B30 blends of and their nanoemulsions are prepared with the 25, 50, 75 and 100 ppm of nano Al2O3. The prepared JME blends and its nanoemulsions are tested in a variable compression ratio (VCR) diesel engine to evaluate the engine performance and emission characteristics.
Findings
The nanoemulsion B20 + 50 ppm has given maximum brake thermal efficiency (BTE), and with the increased proportion of nanoparticle, the BTE was reduced. Also, the specific fuel consumption is lowest (0.2826 kg/kWh) for B20 + 50 ppm at the compression ratio 16.5 and full load which is 4.10% lower than the diesel and 5.8% lower than the B20 blend. As the load increases, NOx emission increases owing to higher peak temperatures in the combustion chamber. The JME-nano Al2O3 emulsion reduces the HC and CO emission compared with all other fuels.
Originality/Value
Novel nano emulsions are prepared, characterized and tested on VCR engine.
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Ismail Hakki Hakkı Akçay, Habib Gürbüz, Hüsameddin Akçay and Mustafa Aldemir
This study seeks the effect on static thrust, thrust specific energy consumption (TSEC) and exhaust emissions of euro diesel-hydrogen dual-fuel combustion in a small turbojet…
Abstract
Purpose
This study seeks the effect on static thrust, thrust specific energy consumption (TSEC) and exhaust emissions of euro diesel-hydrogen dual-fuel combustion in a small turbojet engine.
Design/methodology/approach
Experimental studies are performed in a JetCat P80-SE type small turbojet engine. Euro diesel and hydrogen is fed through two different inlets in a common rail distributing fuel to the nozzles. Euro diesel fuel is fed by a liquid fuel pump to the engine, while hydrogen is fed by a fuel-line with a pressure of 5 bars from a gas cylinder with a pressure of approximately 200 bars.
Findings
At different engine speeds, it is found that there is a decrease at the TSEC between a range of 1% and 4.8% by different hydrogen energy fractions (HEF).
Research limitations/implications
The amount of hydrogen is adjusted corresponding to a range of 0–20% of the total heat energy of the euro diesel and hydrogen fuels. The small turbojet engine is operated between a range of 35,000 and 95,000 rpm engine speeds.
Practical implications
On the other hand, remarkable improvements in exhaust emissions (i.e. CO, CO2, HC and NOx) are observed with HEFs.
Originality/value
This is through providing improvements in performance and exhaust emissions using hydrogen as an alternative to conventional jet fuel in gas turbine engines.
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The physical and chemical properties of a new class of synthetic lubricants, the perfluoroalkylpolyether oils and the polytetrufluoroethylene‐thickened greases made from these…
Abstract
The physical and chemical properties of a new class of synthetic lubricants, the perfluoroalkylpolyether oils and the polytetrufluoroethylene‐thickened greases made from these oils, are described in some detail. The properties which make these products of interest as lubricants for use under severe conditions are shown to be I) excellent thermal and oxidative stability, 2) extreme inertness to many reactive chemicals, 3) broad liquid range and good viscosity‐temperature characteristics, 4) complete nonflammability, 5) good lubricating qualities, 6) compatibility with most elastomers and metals at suitable operating temperatures and 7) insolubility in most common solvents. The commercial process used in the production of these lubricants is described. The oils are disclosed to be fluorine end capped polymers of hexafluoropropylene epoxide having number average molecular weights of from 2000 to 7500, and the preferred thickener for the greases is disclosed to be a telomer of tetrafluoroethylene having a molecular weight of 20,000 to 30,000. A number of the commercial uses of these oils and greases, sold by Du Pont under the trade‐name Krytox®, are described including specific examples of instances where their performance far exceeded that of other available lubricants. Some uses in the space and aircraft industries are also discussed.
Gerasimos T. Soldatos and Erotokritos Varelas
The purpose of this paper is to introduce the factor of emotional intelligence (EI) into the calculus of neoclassical analysis under precautionary saving aiming at stabilizing…
Abstract
Purpose
The purpose of this paper is to introduce the factor of emotional intelligence (EI) into the calculus of neoclassical analysis under precautionary saving aiming at stabilizing consumption in the case of an exogenous output shock.
Design/methodology/approach
The introduction of EI differentiates individual firms in handling production uncertainty and individual consumers in coping with consumption uncertainty, but the source of uncertainty is exogenous and affects all the same; there are no idiosyncratic risks and uncertainties. This in conjunction with the median-voter-theory like approach to agent heterogeneity prompted by EI, replicates the result that aggregates quantitative predictions are almost indistinguishable from their representative agent counterpart in life cycle models of precautionary saving.
Findings
EI corroborates stabilization greatly but only the introduction of a monetary authority would fully stabilize the system by injecting or withdrawing money depending on the state of the economy. Money becomes centrally issued and it would be destabilizing if it was accompanied by central and/or commercial bank seigniorage. Median EI is found to coincide with homo economicus' rationality. These results point to the importance of preserving the institutional character of capitalism as a free enterprise but also a competitive system under a government in the service of the private sector.
Originality/value
Methodologically, this paper acknowledges the mutual interdependence between human action and social structure in the liberal setting in which free enterprise is a socioeconomic process that identifies value through exchange under the sociopolitical process of democracy.
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Hokyung Shim, Jihyun Kim and Jungpyo Hong
The purpose of this paper is to study the electric vehicle (EV) drive efficiency of a traction motor considering regenerative braking according to various motor cores.
Abstract
Purpose
The purpose of this paper is to study the electric vehicle (EV) drive efficiency of a traction motor considering regenerative braking according to various motor cores.
Design/methodology/approach
A software program was developed to predict the driving performance of an EV. It determines the driving mileage, the required power of the traction motor, and the operation points on a torque-speed map when drive cycles are given. The driving performance is calculated from the battery capacity, vehicle specification, and efficiency map of the traction motor computed using the finite element analysis.
Findings
As a result, the motor core is a significant design variable for raising the driving mileage of an EV. It is noted that the change of electrical steels used for the motor core is the lowest priced method of increasing the driving range by 2 km.
Originality/value
The comparative analysis of motor core by replacing 35PN250 to 25PNX1250F results in improvement effects traveling 4.62 and 5.16 km farther in the Simplified Federal Urban Driving Schedule (SFUDS) and Highway Fuel Economy Driving Schedule (HWFET), respectively. It was also verified that regenerative braking system is able to enhance drive efficiency by 29-31.3 km in the SFUDS and 6.5-7.3 km in the HWFET. From comparison of price rise for increasing driving mileage by 2 km, it is noted that the change of electrical steels used for the motor core is the lowest priced method.
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Criticism directed at neoclassical economics has failed to replace it with a similar grand theory. The authors argue that one possible explanation may lie in the failure of…
Abstract
Purpose
Criticism directed at neoclassical economics has failed to replace it with a similar grand theory. The authors argue that one possible explanation may lie in the failure of economists to formulate an opinion as to the philosophical foundations of the author’s object of study. The paper aims to discuss this issue.
Design/methodology/approach
The argument proceeds in two steps. First, the authors review the prevailing philosophical view of “the self-interest theory (S)”, which is one of the most powerful constituents of today’s economics, and social theorizing in general. Second, the authors present a reasoning framework in which rationality becomes intelligible within a schema of integrating the self’s external and internal conditionalities into a unified view of human reasoning.
Findings
Self-interest has been supposed to give the authors direction about what, concretely, to do, but, on the way, the authors have learned that defining rationality is necessarily a life-dependent process. The conflicts of reasons call for a revised S according to which rationality implies consistency among a person’s competing behavioural drivers rooted in three ontological realms, natural, social, and cultural.
Originality/value
First, understanding the purpose of one’s actions in rational terms demands redirecting attention from outcomes in terms of utility, profits, or welfare to a social profile of a rational person, with real life coordinates in space and time, as well as the personal histories of that individual. A change in explaining aspirations leads, and this is the second implication, to change in defining the meaning of economic (or social) behaviour. Decision making is not necessarily a process of virtuously selecting the best available options, but assessing and acting according to the opportunity of choice; it is not about freedom of choice, but about the degree of freedom a person is willing and is able to take advantage of.
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