Efficiency analysis of straight fin with variable heat transfer coefficient and thermal conductivity

In this study, one type of applicable analytical method, differential transformation method (DTM), is used to evaluate the efficiency and behavior of a straight fin with variable thermal conductivity and heat transfer coefficient. Fins are widely used to enhance heat transfer between primary surface and the environment in many industrial applications. The performance of such a surface is significantly affected by variable thermal conductivity and heat transfer coefficient, particularly for large temperature differences. General heat transfer equation related to the fin is derived and dimensionalized. The concept of differential transformation is briefly introduced, and then this method is employed to derive solutions of nonlinear equations. Results are evaluated for several cases such as: laminar film boiling or condensation, forced convection, laminar natural convection, turbulent natural convection, nucleate boiling, and radiation. The obtained results from DTM are compared with the numerical solution to verify the accuracy of the proposed method. The effects of design parameters on temperature and efficiency are evaluated by some figures. The major aim of the present study, which is exclusive for this article, is to find the effect of the modes of heat transfer on fin efficiency. It has been shown that for radiation heat transfer, thermal efficiency reaches its maximum value.     

Springback Analysis of Two-Layer Strips in Clad Cold Bimetal Bending

Recently, multi-layer metallic materials are increasingly being employed in a wide variety of industrial applications in order to create materials with combined functions and higher performances. Based on a nonlinear finite element analysis, the present study aims to develop a model for investigating the effects of sheet thickness and position on the springback of a stainless-steel clad aluminum sheet. It addresses three different types of strain hardening models, namely isotropic, cyclic, and Johnson–Cook (JC). A purely empirical approach, JC considers strain, strain rate, and temperature in elastic–plastic deformation. Good agreements are seen between the obtained results and the experimental verification data, therefore it is concluded that the bending behavior of a bi-layer metallic sheet/strip can be accurately predicted by the proposed model.     

Distance-based-decoding of block turbo codes

List-based algorithms for. decoding block turbo Codes (BTC) have gained popularity due to their low computational complexity. The normal way to calculate the soft outputs involves searching for a decision code word D and a competing codeword B. In addition, a scaling factor /spl alpha/ and an estimated reliability value /spl beta/ are used. In this letter, we present a new approach that does not require /spl alpha/ and /spl beta/. Soft outputs are generated based on the Euclidean distance property of decision code words. By using the new algorithm, we achieve better error performance with even less complexity-for certain BTCs.     

Nanocrystalline Nickel Deposition on the Titanium Alloys Using High Solution Flow Velocity

An innovative process has been developed for electroplating of nickel on titanium surface using fast solution flow technique. Nickel was directly deposited on a titanium alloy without using any pre-treatment process. Level of adhesion was determined using quantitative peel test and characterization of the deposition was performed by scanning electron microscopy. Results showed that the rate of nickel deposition at 60 °C was higher than that of the rate of nickel deposition at 40 °C. Moreover, Watts solution provided higher rate of nickel deposition compared to the sulfate-based nickel solution. The rate of deposition increased with increasing the solution flow velocity from 1.5 to 3 m/s and raising current density from 0.4 × 10⁴ to 1.6 × 10⁴ A/m² for both solution baths. Adhesion test indicated good level of adhesion between the deposited nickel and titanium surface. The bonding toughness increased to 4 J/m² for 1.2 × 10⁴ A/m² as a result of higher deposition rate. However, the mechanism responsible for the coating process was discussed in detail.     

Effect of oxygenates blending with gasoline to improve fuel properties

The purpose of this paper is to study the effect of oxygenate additives into gasoline for the improvement of physicochemical properties of blends.Methyl Tertiary Butyl Ether(MTBE),Methanol,Tertiary butyl alcohol(TBA),and Tertiary amyl alcohol(TAA) blend into unleaded gasoline with various blended rates of 2.5%,5%,7.5%,10%,15%,and 20%.Physicochemical properties of blends are analyzed by the standard American Society of Testing and Materials(ASTM) methods.Methanol,TBA,and TAA increase density of the mixtures,but MTBE decreases density.The addition of oxygenates lead to a distortion of the base gasoline’s distillation curves.The Reid vapor pressure(RVP) of gasoline is found to increase with the addition of the oxygenated compounds.All oxygenates improve both motor and research octane numbers.Among these four additives,TBA shows the best fuel properties.     

Deterioration of concrete in a hydroelectric concrete gravity dam and its characterisation

A hydroelectric concrete gravity dam in the Snowy Hydro network had shown signs of concrete distress in the form of cracking in some sections of the dam wall, and vertical movements in the wall, measured in routine surveys on the crest of the dam wall. Concrete elements of the associated power station had also shown some degree of distress in the form of cracking. Alkali-aggregate reaction (AAR) was considered among other mechanisms as a likely cause of cracking.In order to investigate the main causes of cracking of the various elements of the power station and the dam wall, core samples ranging in length from 0.3 m to 10 m were extracted and investigated for the presence of AAR, its extent, likelihood of continuing reaction, residual expansion potential, and effect on the strength of concrete.Results of the investigation showed that mild AAR was present in some sections of the wall of the power station but not in the floor, where drying shrinkage could have caused the cracking. Mild AAR was also present in sections of the dam wall with minor visible cracking, but it was stronger and more widespread in the badly cracked area. It was suggested that the walls of power station could be treated by appropriate surface coating to mitigate the progress of AAR, and the badly cracked portion of the dam wall be anchored to stabilise the vertical movement. Other portions of the dam wall did not appear to need treatment.     

Analysis of roughness of a sanded wood surface

Due to the non-homogeneity of timber material, the roughness profile of a board is affected by the wood anatomy, thus making the analysis of timber surface quality quite complicated. Currently, there is no reliable method to analyse timber surface quality independent of the timber species or timber properties. The current standard filtering methods used to determine the surface roughness profile from a measured profile or a primary profile fail to produce reliable results in timber surface analysis. This paper proposes a new approach to overcome this shortcoming and to provide more accurate and reliable timber roughness analysis methods. The proposed methods are compared with the current standard methods using data from 35 samples of Messmate (Eucalyptus obliqua) sanded with seven different grit sizes of abrasive (P60, P80, P100, P120, P150, P180 and P240). The results suggest that the proposed methods are more consistent and accurate in describing sanded timber surface quality.     

Effect of cell based team work in productivity improvement at a manufacturing company

This paper report is part of a comprehensive study aiming at establishing a productivity improvement model for an Iranian manufacturing company. We firstly describe the state of affairs encompassing the effects of the prevailing behavioural system which is in turn affected by cultural and environmental conditions, impact of history, geographical situation, state of technology and people's attitude. A team work effort is organised around a cellular manufacturing exercise to demonstrate an effective change in the performance and esisting conditions.     

Weldability of Ferritic Ductile Cast Iron Using Full Factorial Design of Experiment简

The weldability of a ferritic ductile cast iron was investigated as a function of different consumables and welding conditions. A 23 full factorial experimental design was used to analyze the effect of factors and their interac- tions on ultimate tensile strength of weldments. The shielded metal arc welding （SMAW） process was used with two types of consumables （E7018 and ENi-CI） under eight different conditions using as-cast samples. The microstructur- al evolution and fracture mechanisms were investigated by optical microscopy and scanning electron microscopy （SEM）, respectively. The hardness, tensile and impact tests were also performed to determine the weld quality. Based on experiment design, preheat, consumable, cooling condition, preheat cooling and preheat-consumable inter- actions were significant factors. Preheat is the most effective factor and in the case of E7018, preheat and cooling conditions were the most sensible factors. It was found that buttering was the most appropriate welding method for ferritic ductile cast iron.