Brazing is one of the most important techniques known in joining two similar/dissimilar metals/metal–nonmetal combinations for structural, mechanical, and aerospace applications. Brazing joints are formed by melting pure or alloyed foil called braze. Braze is melted in between the two substrates to be joined, and the joint is formed due to inherent adhesion and reactivity between braze and substrate. Copper and nickel are most commonly used brazes in the industry. Copper behavioral studies are mostly aimed at stainless steels (SS), and lot of research is carried out in Cu–SS systems. But, what is the copper behavior with medium carbon steels? What is the grain boundary behavior of copper and its mechanism when the alloying elements in steel are very low? Sandwich experiments were conducted with C45/Cu/C45 systems under an inert gas environment at 1100 °C. Cu was found to be wetting and penetrating the grain boundaries of medium carbon steel such as C45. The depth of penetration varied depending on holding times. The microstructure of the interface was characterized by SEM, and penetration depth was measured by image analysis software for better resolution and accuracy.
production of aluminum and low-melting alloy castings [ 3 ], which provide good quality of products, high surface smoothness, and excellent dimensional and shape accuracy, accompanied by the relatively low production costs. The applications of aluminum die
Authors:György Zoltán Radnóczi, Zoltán Herceg, and Tamás Rafael Kiss
Introduction The evolution of materials science and device technology led to very accurate control of thin film growth and deposition rates. A need for direct measurement of film thicknesses and large distances is obvious, however, the accuracy of
used in robots and smart vehicle navigation systems besides computer vision systems to increase the accuracy and reliability of the system [ 3 ]. The modern localization systems use array (grid) of sensors for localization of objects in general instead
Authors:S. Hajdu, D. Bodnár, J. Menyhárt, and Zs. Békési
The efficiency and accuracy of the modern positioning systems are crucial points in their design. The designers and engineers are highly motivated to find new methods and solutions to the accuracy problem with the biggest mobility and safety. Considerable numbers of solutions are on the market but only some of them can be used in medical industry. The authors will propose some kinematical simulation methods using MATLAB® software. The purpose of these methods is to use Stewart Platform with a better accuracy. The results show that it is possible to simulate Stewart Platform in MATLAB® and it can be used in medical industry.
Non-linear finite element calculations are indispensable when important information of the material response under load of a rubber component is desired. Although the material characterization of a rubber component is a demanding engineering task, the changing contact range between the parts and the incompressibility behaviour of the rubber further increase the complexity of the investigations. In this paper the effects of the choice of the numerical material parameters (e.g. bulk modulus) are examined with regard to numerical stability, mesh density and calculation accuracy. As an example, a rubber spring is chosen where contact problem is also handled.
It is well known that the civil engineering constructions are subjected to cost risk and time overruns. The uncertainties of the cost of construction many times result in disputes among stakeholders. The recent cost fluctuation in sand price in Tamil Nadu is a good example of time and cost overruns. There are too many models developed to predict the cost of construction by using different parameters and tools. The objectives of this research are to analyse the importance of research in this field, the countries focusing on this issue, level of implementation by the practicing engineers, the tools often or successfully used, the difficulties in predicting the cost and the accuracy of prediction and bringing out a useful conclusion to provide the direction for future research. In this research, a sample of 324 research papers out of more than 2000 papers listed in Scopus database between the years 1990 and 2015 were considered and analyzed on five factors. The five factors are 1) authors affiliation – academics, industry or both; 2) country; 3) tools used – ANN, regression, time-series models, etc.; 4) complexity involved or ease of use; 5) accuracy of results. The results show interesting information.
Building life cycle assessment is getting more and more attention within the topic of environmental impact caused by the built environment. Although more and more research focus on the embodied impact of buildings, the investigation of the operational energy use still needs attention. The majority of the building stock still does not comply with the nearly zero energy requirements. Also, in case of retrofitting, when most of the embodied impact is already spent on the existing structures (and so immutable), the importance of the operational energy rises. There are several methods to calculate the energy performance of buildings covering the range from simplified seasonal methods to detailed hourly energy simulations. Not only the accuracy of the calculations, but the computational time can be significantly different within the methods. The latter is especially important in case of optimization, when there is limited time to perform one calculation. Our research shows that the use of different calculation techniques can lead to different optima for environmental impacts in case of retrofitting. In this paper we compare these calculation methods with focus on computational time, accuracy and applicability to environmental optimization of buildings. We present the results in a case study of the retrofitting of a middle-sized apartment house in Hungary.
The main cause of train derailment is related to transverse defects that arise in the railhead. These consist typically of opened or internal flaws that develop generally in a plane that is orthogonal to the rail direction. Most of the actual inspection techniques of rails relay on eddy currents, electromagnetic induction, and ultrasounds. Ultrasounds based testing is performed according to the excitation-echo procedure . It is conducted conventionally by using a contact excitation probe that rolls on the railhead or by a contact-less system using a laser as excitation and air-coupled acoustic sensors for wave reception. The ratio of false predictions either positive or negative is yet too high due to the low accuracy of the actual devices. The inspection rate is also late; new numerical method has been developed in this context: The semi-analytical finite element method SAFE. This method has been applied in the case of anisotropic media , composite plates  and media in contact with fluids . This method has been used successfully for several structures and especially in the case of beams of any cross-section such as rails that are the subject of this work and we were interested in wave propagation in waveguides of any arbitrary cross-section in the case of beams or rails.