Scheduling and sequencing, del 1 Flashcards
Vad innebär scheduling?
Scheduling is the assignment of start and completion times to particular jobs, people or equipment. It applies to all aspects of a value chain, for example planning and releasing orders in a factory, determining work shifts for employees and making deliveries to customers.
Describe staff scheduling
Staff scheduling includes attempts to match available personnel with the needs of the organization by:
- Accurately forecasting demand and translating it into the quantity and timing of work to be done
- Determining the staffing required to persom the work by time period
- Determining the personnel available and the full- and part-time mix
- Matching capacity to demand requirements and developing a work schedule that maximizes service and minimizes costs
Describe appointments
Appointments is reservation of service time and capacity
What does appointments do?
It helps maximize the use of time-dependent service capacity and reduce the risk of no-shows. It reduces the cost of providing services as the service providers are idle less each workday (mindre inaktiva varje arbetsdag). It also helps to accommodate customers and forecast their behaviors.
What is sequencing?
Sequencing is the determination of the order in which jobs or tasks are processed. The better sequencing, the better capacity utilization. The sequencing problem is very complex, the optimization techniques are only used for simple problems.
Formula possible sequences
-n!^m possible sequences
where n is number of orders and m is number of machines
Vad är Process-Focused performance criteria measures?
Flow times = the amount of time a job (flow unit) spends in the shop or factory
Makespan = the time needed to process a given set of jobs
- Short makespan = aims to achieve high equipment utilization and resources by getting all jobs out of the shop quickly
Formula Flow times och Makespan
Fi=Si+Pi where F = flow time of job i, S = start time of job i, P = processing time of job i
M=C_L-S_F where M = makespan of a group of jobs, CL = completion time of the least job in the group, SF = start time of the first job in the group
Vad är due-date criteria measures?
Lateness = differences between the completion time and the dure date (positive or negative)
Tardiness = amount of time by which the completion time exceeds the due date (om lateness är positive)
Formula lateness och tardiness
Li=Fi-Di where Li = lateness of job i, Di = due date of job i, Fi = completion time
Ti=Max(0,Li) where Li = lateness of job i, Ti = tardiness of job
