#lang scheme/base ; Model 2b - 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)) (when (variable-history current-temp) (write-special (history-plot (variable-history current-temp) (format "Ingot ~a Temperature History" i))) (newline)) (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)) (write-special (history-plot (variable-history leave-temp) "Final Temperature Histogram")) (newline) (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))) (write-special (history-plot (variable-history (set-variable-n furnace-set)) "Furnace Utilization History")) (newline) (stop-simulation)) (define (initialize) (current-simulation-max-step-size (/ 1.0 60.0)) (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)