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2 Metrology and Measurement Systems

2 2008

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μ-Scale CMM: A New Diagnostic Tool of Evolved Dimensional and Geometrical Deviations for Bus Diesel Engine Cylinder

Ali S. H. R., Mohamed H. H., Bedewy M. K.

Metrology and Measurement Systems

2008

Vol. 15, nr 3

367-379

μ-scale measurements of dimensional and geometrical features of components require an advanced precise and accurate device such as the CMM machine. Evolved changes in the dimensional and geometrical measurements as referred to benchmark values can be employed as a reliable diagnostic tool in monitoring the functional deterioration of mechanical parts that involve working surfaces during their operation. It is evident that excessive wear in a cylinder bore of an internal combustion engine can dramatically affect the quality of performance, the sealing function, the scheme of lubrication, and eventually the service life span of the piston rings and in turn of the engine as a whole. In this work, precise and accurate measurements of evolved deviations in the diameter, roundness, straightness, and concentricity in a cylinder bore of an air cooled Automotive Diesel Engine using a CMM machine have been carried out and analyzed. The results have been presented, discussed, and interpreted in order to demonstrate making use of them in monitoring the status of the engine during operation. Locations of severe wear occurrence in the cylinder bore are then detected and investigated. The measurements within relevant uncertainties would reflect the quality of engine performance, the suitability of the applied scheduled maintenance plan, and the adverse operating conditions which may have been probably encountered during service life. Thus, in the light of the findings, recommendations can be provided to the engine designer to improve his design regarding changes of material selection and/or surface treatments. Furthermore, an innovative constructional modification may be suggested to homogenize the wear occurrence in the cylinder bore during operation. For instance, a device can be added to the construction in order to cause continuous slow rotation of the cylinder about its geometrical axis while the engine is running, without having to dismantle the components. This may extend the operating life span of the cylinder and in turn reduce the maintenance expenses. In addition, power loss due to friction and wear in the engine may be favorably affected.

Advanced Nanometrology Techniques of Carbon Nanotubes Characterization

Ali S. H. R., Etman M. A., Azzam B. S., Rashad R. M., Bedewy M. K.

Metrology and Measurement Systems

2008

Vol. 15, nr 4

551-561

It has become evident that carbon nanotubes (CNTs) possess exceptionally high physical, mechanical, electrical, and structural properties that made them attractive for researchers to investigate. In this paper, CNTs synthesized by submerged DC arc in deionized water were subjected to six different characterization techniques in order to have an insight into their intrinsic properties. Stages of CNTs growth scenario during their synthesis were captured by Transmission Electron Microscopy (TEM). Images of Scanning Tunneling Microscopy (STM) depicted the spaghetti-like nature of nanotubes sized in the range from 6 to 8 nm diameters with bends and kinks observed. Transmission Electron Diffraction Microscopy (TEDM) images declared the purity of the synthesized CNTs. Also, Fourier Transformation Infra Red (FTIR) spectrum analysis depicted the transmittance and frequency band widths of peaks relevant to the functional groups. In addition, Raman spectrum analysis disclosed the G and D modes with no radial breathing mode (RBM) for a random sample of the synthesized CNTs indicating some defects, strain, oxidation stated of the SWCNTs with the possibility of multiwalled carbon nanotubes existence as well. Thermo Gravimetric Analysis (TGA) reflected the thermal stability of the synthesized CNTs as they sustained temperatures approaching almost 1000°C. Thus, it can be concluded that the used techniques proved to successfully characterize the synthesized CNTs, so that they can be reasonably nominated for suitable potential application.