The effect of surface roughness on tensile strength of the medium density fiberboard (MDF) overlaid with polyvinyl chloride (PVC)

The objective of this study is to determine the effect of the surface roughness on the tensile strength perpendicular to the surface of medium density fiberboard (MDF) overlaid with polyvinyl chloride (PVC). The surfaces of the MDF panels were sanded with four different grit abrasives, 220, 240, 280 and 320-grit, to create different roughness values. The roughness of the panel surfaces were determined in accordance with ISO 4288. The MDF panels were laminated with polyvinyl chloride (PVC) using a polyurethane-based adhesive. A total of 70 samples having the dimensions of 50 × 50 mm from the panels were prepared based on EN 326-1. The universal test machine was used for tensile strength. The test results were statistically analyzed and it was found that the sanding process decreases the surface roughness of the MDF and as the grit size of the abrasives increases, the surface roughness decreases. The surface roughness influences the tensile strength perpendicular to the surface of the overlaid samples. The most suitable surfacing type for lower cost and the highest tensile strength is the sanding with the 240-grit abrasive.     

Factors Affecting the Use of Precast Concrete Systems

The reasons precast concrete systems are not used extensively in the United States were explored through four mail surveys that were sent to 100 contractors, 100 design firms, 100 precast concrete manufacturers, and 100 local labor unions. The findings indicate that most of the prerequisite conditions for the extensive use of industrialized building systems already exist. The findings also indicate, however, that there is a major shortage of expert personnel capable of designing and organizing projects involving precast concrete systems and that almost half the contractors surveyed did not observe significant cost savings when they used precast concrete systems. Architects' and engineers' awareness of precast concrete systems and the number of competent precast concrete designers and erectors can be increased by providing adequate exposure of engineering and architecture students to these systems and by providing frequent and numerous continuous education programs for the benefit of active professionals.     

A depletion load self-aligned technology

Based on an accurate large signal MOSFET model, a computer aided design of the elementary NOR gate using a P channel depletion enhancement self-aligned technology has been done so as to minimize power-speed product. Threshold adjustment and gate self-registration are achieved by ion implantation. Measurements of main electrical and technological parameters are given. Computer aided design results are compared with measured performances on a 99 gates ring oscillator. For a 5 V supply voltage power-speed products as low as 1 pJ are obtained.     

Circumferentially Cracked Bimaterial Hollow Cylinder Under Mechanical and Transient Thermal Loading

The analytical solution for the problem of a circumferential inner surface crack in an elastic, infinitely long composite hollow cylinder, made of two concentric perfectly bonded transversely isotropic cylinders is considered. Uniform axial loading and thermal loading in the form of a sudden cooling on the inner boundary are considered. Out of 10 material parameters involved, two bimaterial parameters and three material parameters for each layer upon which the stress intensity factor depends under uniform loading, are identified. The problem is reduced to a singular integral equation that is solved numerically. Stress intensity factors are presented for various values of material and geometric parameters.     

Computation of Instantaneous Fuel Consumption for the Determination of Combustion Efficiency with Special Reference to Coal Briquette Size

This study comprises of the computation of instantaneous fuel consumptions as a straight means for the interpretation of combustion-related characteristics of coal. The model relies on the determination of the extent of combustion by the calculated fuel combustion amounts at specific instants in order to examine the oxidation behavior and possible influences governed by any variable of interest. In this context, coal briquettes prepared by varying dimensions with and without a volume constraint were evaluated and instantaneous fuel consumptions corresponding to the determined instants were computed for comparison rather than introducing the model with a single experiment. Thus, the influences imposed by the enlargement of the briquette volume as well as by the variations in the compactness of briquettes on the effectiveness and efficiency of combustion reactions were dealt. The applicability of the model was checked by the trends revealed from the view of reaction kinetics in terms of activation energies. At the end of the study, the results deduced on the grounds of instantaneous fuel consumption values were seen to have been in full confirmation by those related to reaction kinetics, showing the applicability of the model in reflecting the particular cases during a combustion reaction.     

The influence of the waste ethylene vinyl acetate copolymer on the thermal degradation of the waste polypropylene

The pyrolysis of the waste polypropylene (PP), the waste ethylene vinyl acetate copolymer (EVA) and their blends has been carried out in a fixed bed reactor at 500 °C. The effect of different ratios of the waste EVA in the waste PP/EVA blends on the thermal degradation of the waste PP was investigated in terms of both product distributions and liquid fuel properties. The compositions of pyrolysis products were characterized in detail. The liquid products from the pyrolysis of the waste PP, the waste EVA and their blends were analyzed using different analytical techniques and fuel properties of pyrolytic liquids were investigated in comparison with commercial diesel. There were no synergistic effects between products from the waste PP and products from the waste EVA. While the ratio of the waste EVA increased in the waste PP/EVA blends, aromatic content of the pyrolytic liquids increased and subsequently paraffinic content of the pyrolytic liquids decreased. In addition, the boiling point distributions of pyrolytic liquids derived from the waste PP/EVA blends were found to be similar for all tested ratios of the waste PP/EVA blends.     

Experimental analysis of maximum valve lift effects in cam-follower system for internal combustion engines

Designing valve lift of cam-follower system is very important for improving dynamic performance of internal combustion engines. Potential problems due to unwanted vibrations in high-speed engine are the follower jump, colliding surface of the valves, and seats which cause collide in a cam-follower system. The degree of collide depends on the valve lift value and valve closing velocity. Large forces and stresses are introduced when the cam and follower collide. This might cause early failure of the system due to unwanted vibration. The main purpose of present experimental study was to investigate and analyze the dynamic behavior of the cam-follower system for different valve lift values and operating speeds using time domain and frequency domain analysis technique. Two cases for maximum valve lift values of 8 and 10 mm were tested with corresponding operating speeds of 450, 930, 1440, 1950 and 2430 rpm. From the results, it was observed that the higher the operating speed, the higher amplitude values were obtained. Statistical analysis of obtained data showed that the 10 mm valve lift produced much more power than the 8 mm valve lift.