Different distribution of H1-H2 Epstein-Barr virus variant in oropharyngeal virus and in biopsies of Hodgkin''s disease and in nasopharyngeal carcinoma from Algeria

Ten clinical and food Listeria monocytogenes strains isolated during the epidemiological investigations of episodes of listeriosis (one outbreak and two sporadic cases) that occurred in northern Italy during 1993-1995 have been examined by DNA macrorestriction pattern analysis obtained by PFGE and RAPD typing, in order to confirm the food vehicle of infections. The same DNA profiles within the isolates from the three episodes were obtained by both techniques. The Apal and Smal PFGE profiles and RAPD patterns with primer OPM-01 confirmed the close relationship between strains from two distinct episodes. However, RAPD analysis with primer UBC-127 distinguished between these L. monocytogenes isolates.     

An investigation of tool wear in high-speed turning of AISI 4340 steel

A commercially available insert has been used to turn an AISI 4340 steel at speeds placed between 325 and 1000 m/min. The flank wear was measured in connection to cutting time. This is to determine the tool life defined as the usable time that has elapsed before the flank wear has reached the criterion value.It is shown that an increase in cutting speed causes a higher decrease of the time of the second gradual stage of the wear process. This is due to the thin coat layer which is rapidly peeled off when high-speed turning.The investigation included the realization of a wear model in relation to time and to cutting speed. An empirical model has also been developed for tool life determination in connection with cutting speed.On the basis of the results obtained it is possible to set optimal cutting speed to achieve the maximum tool life.     

Effects of sandblasting on the efficiencies of solar panels

Photovoltaic solar-energy can be a solution, if efficiently used, for providing electrification, water pumping and communications in inaccessible regions as in the south of Algeria. The glass protected solar panels made for these purposes are, however, constantly exposed to the damaging effects caused by sandstorms. These occur particularly in spring with velocities that can reach 120 km/h, and for various durations, typically 48 h. The small particles of sand (of average size <120 μm) rise high into the atmosphere, and the relatively large particles (average size >120 μm) remain at lower altitudes and at ground level. This preliminary work considers the effects of the sandblasting duration on the efficiencies of solar panels. The results show that the solar panels' efficiencies decrease during sandstorms, and some of these decreases are permanent when the protective glass sheets are damaged by erosion.     

The modelling of bolted flange joints used with disc springs and tube spacers to reduce relaxation

Bolted flange joints are prone to leakage when exposed to high temperature. In several cases, the root cause is relaxation that takes place as a result of material creep of the gasket, the bolt and the flange. One way to overcome this problem is to make the joint less stiff by introducing disc springs or the use of longer bolts with spacers. Although widely used, these two methods have no reliable analytical model that could be used to evaluate the exact number of washers or length of the bolts required to reduce relaxation to a minimum acceptable level.This paper describes an analytical model based on the flexibility and deflection interactions of the joint different elements including the axial stiffness of the flange and bolts, used to evaluate relaxation. The developed analytical flange model can accommodate either disc springs or longer bolts with spacer tubes to reduce the bolt load loss to a maximum acceptable value. This model is validated by comparison with the more accurate FEA findings. Calculation examples on a bolted flanged joint are presented to illustrate the suggested analytical calculation procedure.     

On the Effects of Subgrade Erosion on the Contact Pressure Distribution under Rigid Surface Structures

The performance of rigid surface structures such as concrete pavements and slabs-on-grade supported by a deteriorated subgrade and experiencing local contact loss is investigated experimentally and numerically in this study. A laboratory setup has been designed to facilitate the simulation of subsurface erosion and measure the changes in contact pressure at selected locations under a slab-on-grade supported on granular material. The presence of erosion voids under a slab-on-grade can lead to rapid increase in the contact pressure in the immediate vicinity of the void in addition to an increase in tensile stresses at the outermost fibers of the slab. This preliminary study suggests that efforts to detect and arrest the growth of erosion voids under slabs-on-grade should be made before the voids reach the size where significant loss of support develops and the tensile strength of the slab material is exceeded.     

Influence of finishing by burnishing on surface characteristics

The aim of this study was to analyze the evolution of residual stresses, microhardness, and roughness in relation to the finishing process. The x-ray diffraction (XRD) technique was used to determine the residual stresses, which were measured from the surface to the bottom of the machined workpiece. Processes that were studied included turning, grinding, and burnishing. Burnishing was done on a surface that was initially turned, or turned and then ground. A duplex stainless steel was used in this study. This material belongs to a high-strength stainless steel family with high corrosion resistance properties. We noted that the burnishing process produces the best quality of the surface when compared with turning or grinding.     

Influence of machining by finishing milling on surface characteristics

The aim of this study is to analyse the evolution of residual stresses, microstructure, microhardness and roughness in relation to the different parameters of milling. For finishing milling, parameters are cutting speed and feed. The hole drilling strain gage technique was used to determine the residual stresses. These are measured from the surface to the bottom of the treated workpiece. Two different materials were used in this study: a carbon steel (CS) and a duplex stainless steel (DSS). The latter belongs to a high strength stainless steel family with high corrosion resistance properties. In this study, we have used the experimental system method to analyse the evolution of different surface characteristics in connection with cutting phenomena which are cutting forces, chip geometry and cutting temperature. We have noted that a high value of cutting speed used with a small value of feed improves the quality of the machined surface.