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Question on N Job - 1 Machine ( Sequencing)
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This lesson throws light on question on N job - 1 Machine

Harshit Aggarwal
Cleared UPSC ESE twice with Rank 63 and 90 in mechanical engg. Got 99 percentile in GATE. Cracked ONGC, BHEL,ISRO, SAIL, GAIL successfully

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Unacademy user
அர்ஜெண்டினா
KP VENKAT
a year ago
Very good correct answer
  1. COURSE INDUSTRIAL ENGINEERING LESSON : QUESTION ON N JOB 1 MACHINE (SEQUENCING)


  2. ABOUT ME Graduated from NIT Nagpur in 2008 Cleared Engineering Services Examination (ESE-UPSC) Exam Got the offer letter from most of the Maharatna and Navratna Companies Cleared GATE Exam Rate, Review, Recommend, Share Follow me on Unacademy at: https://unacademv.in/user/harshit aggarwal


  3. DIFFERENT TIMES I. Job Flow Time: It is the time for a job from some starting point until that job is completed. 2. Make Span Time: It is the time from when processing begins on first job in the set until the last is completed 3. Tardiness :The tardiness of a job is the amount of time after its due date that the job is completed 4. Average number of jobs in system: For a fixed set of job this will be equal to total flow time for all the jobs divided by make span time.


  4. QUESTION A set of jobs are to be machined on a single machine. Obtain a sequence using SPT and EDD rule Also calculate Make Span Time, Job flow time for each job, Average flow time per job, Average Tardiness(job),Average number of jobs in a system, No. of tardi jobs. Job Processing Due Date me Using SPT Rule first 34 32 46 36 64 10 C 16 D 6 E 18 F 12 4


  5. USING SPT RULE Jobs Processi Due Job Flow rdiness ng Time Date Time 36 32 34 Make Span Time 70 lotal Job Flow Time 202 Average flow time per job 202/6 33.66 . Total Tardiness 12 . Tardiness per job12/62 . No. of tardi jobs2 C and E are tardi iobs 0+6-6 6+8-14 14+10-24 0 24+12-36 0 36+16-52 6 52+18-70 6 10 Average number of jobs in system lotal job flow time / Make Span Time 202/702.88 46 18 64 20212


  6. USING EDD RULE Job ProcessingD ue Job Flow Tardiness Date 32 34 36 Time 0+8 = 8 8+10 I8 18+6 24 24 + 12 36 0 Make Span Time 70 lotal Job Flow Time 208 Average flow time per job Total Tardiness=12 SI ime T 20%6-34.66 . A 10 D 6 F 2 .Tardiness per job 12/62 .No. of tardi jobs2 C and E are tardi jobs .Average number of jobs in system Total job flow 2.97 time / Make Span Time-208/70 C 16 46 36 + 16 52 6 Note: For N job on one machine SPT rule always produces a sequence that has smallest average flow time and average no. of obs in system. For this reason SPT rule is preferred E 18 64 52 + 18 70 6 12 208


  7. QUESTION 4 jobs are to be processed on a machine as per date listed in the table. I. If the earliest unit rule is used to sequence the job. Find the number of jobs delayed. 2. Using SPT rule find the total tardiness. Job Processing Due Time Date 4 7 19 17 4


  8. SOLUTION I. Using EDD Rule Job Processing Due Job Flow Tardiness Date Time Time 0+4-4 0 4+7 11 I1+8-192 17 19 19+2-21 2 3 Jobs are delayed


  9. SOLUTION 2. Using SPT Rule Jo Processing Due Date Job Flow Tardinesss b Time Time 0+2=2 2+4-6 0 6+7-13 13+8-21 4 19 4 4 17 Total Tardiness 8


  10. THANK YOU