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Full-Text Articles in Mechanical Engineering

Relay Ladder Logic And Petri Nets For Discrete Event Control Design : A Comparative Study, Edward Twiss May 1996

Relay Ladder Logic And Petri Nets For Discrete Event Control Design : A Comparative Study, Edward Twiss

Theses

In the 1960's and earlier discrete event systems (DES) were controlled by hardwired electromechanical relay systems. In 1969 an electronic programmable logic controller (PLC) was introduced. PLC's have been programmed utilizing relay ladder logic (RLL). RLL is a graphical programming language with software "devices" used to emulate electromechanical devices. RLL programs, however, often become large and difficult to understand because its graphical representation of physical switching devices obscures the discrete event dynamics inherent in the process to be controlled. Petri nets are a methodology for modeling discrete event systems (DES). Using a Petri net based controller, a control strategy could …


Design And Analysis Of Environmentally Safe Cooling Systems For Machine Tools, Haiping Xu Jan 1996

Design And Analysis Of Environmentally Safe Cooling Systems For Machine Tools, Haiping Xu

Theses

Many cooling systems of metal cutting and both their advantages and disadvantages have been reviewed. The cutting forces' relationships, stress distribution, energy consumption and heat generation of orthogonal processes are discussed. A two-dimensional finite element model has been developed to design and analyze a new proposed cooling device, which comes from the idea of "A Novel Cooling Device" proposed by Billatos et al. First, a thermal calculation is completed to compare the temperature difference between two different shapes of coiled pipe. Then, three different cutting conditions, which were considered in the experiments by Childs et al, are conducted under three …


Design For Quality Manufacturability Analysis Of Total Nonconformity Damaged Parts, Samir R. Gami Jan 1996

Design For Quality Manufacturability Analysis Of Total Nonconformity Damaged Parts, Samir R. Gami

Theses

The competitive nature of modern manufacturing, demands that innovative approaches be applied in order to have a competitive edge. Shortening the product development cycle, the period from initial design to full production, is a priority for most manufacturers today. The DFQM methodology addresses the issue of quality manufacturability (QM) - the likelihood that defects will occur during manufacture of a product in a standard plant. As a consequence, DFQM helps to shorten the design cycle time. The DFQM architecture identifies a variety of design factors and variables that influence specific defects. This process of influencing defects can be described by …