Manufacturing Engineering

Passive means of vibration attenuation have been employed successfully and efficiently in machining systems such as turning and milling. Traditional approach to controlling vibration in a milling system is to develop control mechanisms for cutting tools or machine spindles. However, due to the nature of milling operations where the cutting tools rotate at high speed, the passive vibration control methods

ABSTRACT Workflow systems utilize a process model for managing business processes. The model is typically a directed graph annotated with activity names. We view the execution of an activity as a time interval, and present two new algorithms for synthesizing process models from sets of systems’ executions (audit log). A model graph generated by each of the algorithms for a process, captures all its executions and dependencies that are present in the log, and preserves existing parallelism.We compare the model graphs synthesized by our algorithms to those of Agrawal et al. [Mining process models from workflow logs, in: Proceedings of the Advances in Database Technology (EDBT’98), 6th International Conference on Extending Database Technology, Valencia, Spain, 23–27 March 1998, Lecture Notes in Computer Science, Proceedings vol. 1377, Springer, Berlin, 1998] by running them on simulated data. We observe that our graphs are more faithful in the sense that the number of excess and absent edges is consistently smaller and it depends on the size and quality of the log. In other words, we show that our time interval approach permits reconstruction of more accurate workflow model graphs from a log.

Axial compression tests were performed on round tubes of different sizes and made of aluminium and mild steel, both in as-received and annealed conditions. Length to diameter and diameter to thickness ratios of these tubes were varied in different tests, and cut-outs in the form of circular holes, varying in diameter, number and position, were laterally drilled in them. Typical histories of their deformation and load-compression curves are presented and the influence thereon of the annealing process, the tube size, or the cut-outs is discussed. Relations are presented to describe these influences and to express the first peak and mean collapse loads in terms of the Vickers hardness number. It is seen that the presence of holes in the tubes alters their mode of collapse and, as a consequence, affords the possibility of avoiding Euler buckling even when relatively much longer tubes are employed.

ABSTRACT Filler material choice for repair welding of stop valve spindle of thermal power plant by-pass pipeline was presented in this paper. Repair welding of the stop valve spindle was necessary because of plant operating problems due to very frequent localized damage appearance in the form of erosive wear on it. For this purpose it was necessary to choice appropriate filler material with high wear resistance characteristic. Experimental investigation and testing (hardness measurement, chemical composition analysis and microstructural investigation) of prepared specimens after welding simulation with different kind of filler material was performed. On the basis of obtained results it was recommended procedure for application of the filler material with generally preferable characteristic.

Plastic electronic packages are known to absorb moisture when exposed to humid ambient conditions during storage in tape and reel in the factory. Reliability becomes a concern when packages are exposed to a humid environment for a prolonged time and then processed through a reflow oven. Thermo-mechanical and moisture induced interfacial stresses generated between the die attach and die may