Papers by Keyword: Temperature

Abstract: This paper presents the simulation results of variation in pile capacity with temperature and suction. The end bearing, shaft friction and ultimate bearing capacities at various values temperature and matric suction were simulated. The simulation results show that the end bearing capacity decreased with increasing temperature but increased with increasing matric suction. The results also show that, with increasing temperature, the shaft friction and ultimate bearing capacities decreased at low to moderate level of suction but increased at low temperature and high level of suction. With increasing matric suction, the shaft friction and ultimate bearing capacities increased at moderate to high level of temperature but decreased at low temperature and high level of suction.

Abstract: The possibility of compliance with the required technological soldering conditions and ensuring their reproducibility for wave soldering, laser soldering, convection soldering have been researched. Comparing the experimental data to the results of mathematical modeling allowed selectng optimal modes of the wave, convection and laser soldering of electronic devices. The conclusion about the prospects of the analytical dependencies to improve mechanical soldering of electronic devices for any purpose. When heating by convection or wave solder, the temperature along the depth of the solder joints is less than when the contact or laser soldering. It was found that the temperature of the solder joints with infrared and laser soldering can be estimated based on the heat equation for a semi-infinite plate with a given heat flow on the surface. Warming up of the printing unit and, consequently, the solder joints when soldering, convection can be described by equations of the regular mode.

Abstract: The presence of gas in steel is a problem in terms of quality, by the way how is influenced steels mechanical and technological characteristics.Current steel making technology allows inclusion of gas content at relatively low value, but under current conditions, it places a great emphasis on the purity of the steel and the superior mechanical and technological properties, secondary treatment is required (ladle metallurgy) and, if possible, even the treatment of liquid steel in vacuum installations. The paper presents the influence of the main parameters of vacuum treatment (treatment duration, high vacuum period) and thermic parameters of steel (input and output temperature of the steel in installation) relative to hydrogen and nitrogen contents from steel for processing on automatic machines. Correlations obtained are presented in Excel and Matlab both the analytical and graphical form.

Abstract: In this Study a Heat Transfer Model in Combination with Experimental Tests is Used to Determine the Portion of Plastic Work that is Converted into Heat (also Known as the Taylor-Quinney Coefficient, Inelastic Heat Fraction or IHF and Generally Noted β) during the Deformation of Two Modern Automotive Advanced High Strength Steels (AHSS) DP600 and DP1000. Therefore, Uniaxial Tension Tests were Performed under Vacuum in a Deformation-Dilatometer and the Temperature was Captured by Fine-Wire Thermocouples on Three Different Points on the Surface of the Tensile-Specimen during the Plastic Deformation. Afterwards, a Heat Transfer Model was Used to Calculate the Heat Loss at the Points of the Temperature Measurements and they were Accounted in the Final Energy Balance to Determine the Fraction of Plastic Work Converted to Heat. the Results Show that the Fraction of Plastic Work Converted into Heat is Decreasing from 1 to 0.21 over a Tensile Strain Range of 0 to 0.18. Finally, a Finite Element Model of the Tensile Test was Used to Show the Improvement of the Determined Factor in the Calculation of the Temperature Field Compared to the Classical Assumption that β Equals to 0.9.

Abstract: Floor impact sound is one noise in apartment houses that cannot be avoided. In order to reduce floor impact sound, a floating floor system using resilient materials has been generally applied. Floor impact sound insulation performance of the floating floor system is dependent on the physical property (dynamic stiffness) of resilient materials. This study investigated the effect of temperature changes on resilient materials used in the floating floor system and on dynamic stiffness. Ethylene vinyl acetate (EVA) and expanded polystyrene (EPS) were used as resilient materials, and dynamic stiffness was measured during three stages of temperature change condition. The measurement result showed that as the temperature decreased, dynamic stiffness also increased. This study also analyzed the effect of changes in outdoor temperature on the heavyweight impact sound level with respect to concrete buildings with wall slabs. The floor impact sound level tended to increase during the winter season, when the outdoor temperature was low.

Abstract: Numerical study of atmospheric ice accretion on circular cylinders in duplex configuration has been carried out at different operating and geometric conditions. Analyses showed a difference in ice accretion on both cylinders, as streamline accumulated ice shapes were observed along front cylinder and irregular ice shapes were found along rear cylinder. Results also showed a change in accreted ice load and ice shape along rear cylinder with the change in distance between both cylinders. Parametric study at different droplet sizes and temperatures showed a variation in ice accretion. This prelimenary research work provides a useful base for better understanding and further investigation of atmospheric ice accretion on circular overhead conductors in duplex configuration, installed in cold climate of high north regions.

Abstract: The initiation time of reinforcement was researched for reinforced concrete (RC) members along coast regions under chlorine salt ingress and local micro-climate. Based existing chlorine erosion model, when local temperature and relative humidity were considered, the initiation time of reinforcement for RC members were calculated by using Monte-Carlo method, and the influence parameters of the initiation time were researched. According to probability theory, the probability distribution and density of the initiation time was given for RC members in tropical, subtropical and temperate zone along coast in china, for example Haikou City, Shanghai City, and Tianjin City. The research results showed: The impact on the initiation time from local temperature and relative humidity should not be ignored. It should be reasonable to consider when RC members were designed. This would be useful for structure strengthening, maintenance, and remaining life prediction.

Abstract: In the paper there are summarized results of diffusion properties of mortars. Water vapour permeability represented by diffusion thicknesses and water vapour resistance factors are except mechanical properties the most important physical parameters of historic buildings. These parameters are influenced by border conditions among that mainly temperature, relative humidity and barometric air pressure belong. It is necessary to know these parameters to understand a material behaviour after a flood. They are decisive for a determination how quick a diffusion speed rate will be and a drying process will take. Everything depends on a type of binder, a material of a structure itself and primarily on properties of mortar and plaster and finishing. After a flood it is necessary to know when users of buildings can start to make rehabilitations and which of them are proper for particular material and when can return to their homes.

Abstract: Bone drilling is often used in trauma care, orthopedic and other type of surgical procedures. The elevated temperatures caused by friction may lead to temperature induced bone necrosis. This paper presents an analysis of the effect vibration assisted drilling has on the drilling temperature of the compact bone.The experimental setup was developed and two-type experiments have been conducted. The main aim was to analyze the low frequency vibrations assisted drilling effect on the drilling temperature of poly-methyl methacrylate (PMMA) and bone samples. The temperatures at the exit hole were measured using the thermal camera. The rotational speed of the drill, applied force, parameters of the drill and the samples were considered as constant, whereas the amplitude and frequency of vibrations were varied during the experiments. The obtained experimental data showed the decrease in the drilling temperatures of the vibrated bone samples, as compared to the conventional drilling. It should be noted that further investigation and research related to the vibration assisted drilling should be carried out using different type of bone samples and experimental conditions.

Abstract: The applications of stainless steels may be meeting in chemical industry, food industry, civil building, but present an increased interest also in machine constructions or household.This paper highlight the structural modifications obtained after temperature variations for AISI 321 stainless steel. The modifications of structure and proprieties can be induced by heat treatments applied to semi-products before or after the obtaining of final parts, but also by heating at regimes which respect the exploitation conditions of part. In the experiments, it is applied quenching to put into solution, with modification of final treatment temperature and maintaining time, aiming the dissolution of complex carbides and in this mode an easy processing. The treatment parameters were chosen, after the determination of alloying elements by AISI 321 samples, by optic spectrometry. The dilatometric analysis aimed to highlight the structural modifications, specific to thermal fatigue phenomenon, due to temperatures variations.