; Model 2a - Continuous Simulation Model
(require (planet "simulation-with-graphics.ss"
("williams" "simulation.plt")))
(require (planet "random-distributions.ss"
("williams" "science.plt")))
;; Simulation Parameters
(define end-time 720.0)
(define n-pits 7)
; Data collection variables
(define total-ingots 0)
(define wait-time #f)
(define heat-time #f)
(define leave-temp #f)
;;; Model Definition
(define random-sources (make-random-source-vector 4))
(define furnace-set #f)
(define furnace-temp 1500.0)
(define pit #f)
(define (scheduler)
(let loop ((i 0))
(schedule now (ingot i))
(wait (random-exponential (vector-ref random-sources 0) 1.5))
(loop (+ i 1))))
(define-process (ingot i)
(let* ((initial-temp (random-flat (vector-ref random-sources 1) 100.0 200.0))
(heat-coeff (+ (random-gaussian
(vector-ref random-sources 2) 0.05 0.01) 0.07))
(final-temp (random-flat (vector-ref random-sources 3) 800.0 1000.0))
(current-temp (make-continuous-variable initial-temp))
(arrive-time (current-simulation-time))
(start-time #f))
(if (= (modulo i 100) 0)
(accumulate (variable-history current-temp)))
(with-resource (pit)
(set-variable-value! wait-time (- (current-simulation-time) arrive-time))
(set-insert! furnace-set self)
(set! start-time (current-simulation-time))
(work/continuously
until (>= (variable-value current-temp) final-temp)
(set-variable-dt!
current-temp
(* (- furnace-temp (variable-value current-temp))
heat-coeff)))
(set-variable-value! heat-time (- (current-simulation-time) start-time))
(set-variable-value! leave-temp (variable-value current-temp))
(set-remove! furnace-set self))
(if (variable-history current-temp)
(printf "~a~n" (history-plot (variable-history current-temp)
(format "Ingot ~a Temp History" i))))
(set! total-ingots (+ total-ingots 1))))
(define (stop-sim)
(printf "Report after ~a Simulated Hours - ~a Ingots Processed~n"
(current-simulation-time) total-ingots)
(printf "~n-- Ingot Waiting Time Statistics --~n")
(printf "Mean Wait Time = ~a~n" (variable-mean wait-time))
(printf "Variance = ~a~n" (variable-variance wait-time))
(printf "Maximum Wait Time = ~a~n" (variable-maximum wait-time))
(printf "~n-- Ingot Heating Time Statistics --~n")
(printf "Mean Heat Time = ~a~n" (variable-mean heat-time))
(printf "Variance = ~a~n" (variable-variance heat-time))
(printf "Maximum Heat Time = ~a~n" (variable-maximum heat-time))
(printf "Minimum Heat Time = ~a~n" (variable-minimum heat-time))
(printf "~n-- Final Temperature Statistics --~n")
(printf "Mean Leave Temp = ~a~n" (variable-mean leave-temp))
(printf "Variance = ~a~n" (variable-variance leave-temp))
(printf "Maximum Leave Temp = ~a~n" (variable-maximum leave-temp))
(printf "Minimum Leave Temp = ~a~n" (variable-minimum leave-temp))
(printf "~a~n"
(history-plot (variable-history leave-temp)
"Final Temperature Histogram"))
(printf "~n-- Furnace Utilization Statistics --~n")
(printf "Mean No. of Ingots = ~a~n"
(variable-mean (set-variable-n furnace-set)))
(printf "Variance = ~a~n"
(variable-variance (set-variable-n furnace-set)))
(printf "Maximum No. of Ingots = ~a~n"
(variable-maximum (set-variable-n furnace-set)))
(printf "Minimum No. of Ingots = ~a~n"
(variable-minimum (set-variable-n furnace-set)))
(printf "~a~n"
(history-plot (variable-history (set-variable-n furnace-set))
"Furnace Utilization History"))
(stop-simulation))
(define (initialize)
;; Set continuous simulation settings
(current-simulation-step-size (/ 1.0 60.0))
(current-simulation-control #f)
;; ---
(set! total-ingots 0)
(set! wait-time (make-variable))
(set! heat-time (make-variable))
(set! leave-temp (make-variable))
(set! pit (make-resource n-pits))
(set! furnace-set (make-set))
(accumulate (variable-history (set-variable-n furnace-set)))
(tally (variable-statistics wait-time))
(tally (variable-statistics heat-time))
(tally (variable-statistics leave-temp))
(tally (variable-history leave-temp))
(schedule (at end-time) (stop-sim))
(schedule (at 0.0) (scheduler)))
(define (run-simulation)
(with-new-simulation-environment
(initialize)
(start-simulation)))
(run-simulation)