Performance criteria-aspects of scheduling , Mechanical Engineering

Assignment Help:

Performance Criteria

This is assumed that an FMS is the part of a superior production process. Consequently the performance of the FMS is not a major goal but imply to attain cost-efficient timely production in the whole system. In hierarchical decentralized systems, the recent state of technology, complex production systems should be controlled. The decisions in the subsystems should be based upon local due dates and local earliest possible beginning times that are offered via the higher-level scheduling system. For a smooth operation of the whole system, a narrow distribution of the deviations from planned process is necessary.

Thus, the usual performance criterion is considered as minimal tardiness. Earliness is neither honored nor punished, since in a complex system the advantages of local earliness are doubtful. The tardiness of all jobs that are ended on time or earlier is zero. Throughput time or machine consumption are not utilized as criteria, since on the long run (we utilize extremely long horizons for the evaluation) the task of a production system is to generate the goods to be delivered on the right time where the demanded throughput times may vary extremely among the jobs; hence, the average throughput time might be a misleading indicator. Obviously, tardiness must all time be looks relative to a specific demanded flow factor distribution, indicated via the time pressure level in the present case.

There are a number of various reasonable measures of tardiness. This is identified that these dissimilar measures in usual cannot be minimized concurrently. In cases of high loads of the system, algorithms which prefer shorter operations offer good values of average tardiness Tmean but at the expense of a minute fraction of the jobs that suffer from extremely large delays. If an FMS is integrated in a superior overall production process, not only a minute value of Tmean is desired but also a narrow distribution of the delays approximately this value, since larger discrepancies among planned and attained completion times create problems for the another local schedule. Thus, the subsequent three criteria are utilized:

Average overall tardiness (over all jobs)

 

 

 

                           581_Performance Criteria-aspects of scheduling.png

Notice that Tmean  is not subtracted in the definition of Trms, consequently Trms  is not a variance but a measure of concerns tardiness and the dissimilarity of Tmean  and Trms  implies the width of the distribution. The associate emphasis is specified to any of the three criteria depends upon the exact situation. Generally, Trms will be the most suitable single criterion.


Related Discussions:- Performance criteria-aspects of scheduling

Gears, how to prevent absolute noise during meshing of gears

how to prevent absolute noise during meshing of gears

Balancing of several masses rotating in different planes, The crank shaft o...

The crank shaft of a high speed pump has a parallel shaft of 2.5 cm diameter and 48 cm in length. It carries three eccentrics each of 6 cm in diameter and uniform thickness of 1.8

Thermodynamics, show that energy of an isolated system is conserved

show that energy of an isolated system is conserved

Introduction to general safety and service tips , INTRODUCTION: Safety is ...

INTRODUCTION: Safety is very important which is often neglected at our workplaces. Small precautions if carried out regularly can ensure safe, hygienic and clean environment at ou

Calculate size of blank required for drawing, Calculate Size of Blank Requi...

Calculate Size of Blank Required for Drawing A flanged cup shown in Figure is to be produced by deep drawing. Calculate the size of the blank required for drawing.

Compute position and magnitude of the resultant force, Compute the position...

Compute the position and magnitude of the resultant force acting on the framework shown below. What is the moment of the force system ?

Describe the basic concept of descriptive interface, Describe the basic con...

Describe the basic concept of descriptive interface Descriptive interfaces are the window to other CAD systems, to the master databases or to the manufacturing activities. The

Explain the procedure of removal for valves, (a) Explain the procedure of r...

(a) Explain the procedure of removal for valves. (b) How should one remove valve guide from cylinder head? (c) What is the use of piston side base? (d) What is the use of

Mounting systems for the welding head-fixed type:, Fixed type In this se...

Fixed type In this set up, the welding head is kept fixed and the movement required during welding is provided through in the jobs to be welded. A typical application of this arr

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd