unit ReliabilityMain;

interface

uses
  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
  TeEngine, Series, ExtCtrls, TeeProcs, Chart, Math;


const
  STOP_TIME = 1000000000;
  
  T1 = 1000.0;
  nu = 1.0;
  m  = 1000.0;
  sigma = 2000.0;
  mu = 0.002;


type
  TForm1 = class(TForm)
    Chart1: TChart;
    Series1: TBarSeries;
    Series2: TBarSeries;
    procedure FormKeyDown(Sender: TObject; var Key: Word;
      Shift: TShiftState);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

  TDevice = record
    OK, WasOK: Boolean;
    BlockOK: array [1..3] of Boolean;
    BlockNextSwitchTime: array [1..3] of Double;
    TotalOKTime: Double;
    NumCrashes: Integer;
  end;


var
  Form1: TForm1;
  Device: TDevice;
  t, tOld, tOut: Double;


implementation

{$R *.DFM}


function Weibull(T1, nu: Double): Double;
begin
Weibull := Power(-T1 * ln(Random), 1 / nu);
end;


function Expon(mu: Double): Double;
begin
Expon := -(1 / mu) * ln(Random);
end;


function Norm(m, sigma: Double): Double;
var
  S: Double;
  i: Integer;
begin
repeat
  S := 0;

  for i := 1 to 12 do
    S := S + Random;

  Result := m + sigma * (S - 6);
until Result > 0;  
end;



procedure CheckOK(var D: TDevice);
begin
D.WasOK := D.OK;

D.OK := (D.BlockOK[1] and D.BlockOK[2]) or (D.BlockOK[1] and D.BlockOK[3]) or (D.BlockOK[2] and D.BlockOK[3]);

if D.OK then
  D.TotalOKTime := D.TotalOKTime + (t - tOld);
  
if (not D.OK) and D.WasOK then
  Inc(D.NumCrashes);
end;


procedure TForm1.FormKeyDown(Sender: TObject; var Key: Word; Shift: TShiftState);
var
  i, j: Integer;
begin
// initialization

Randomize;

t := 0;
tOld := 0;
tOut := 10;

with Device do
  begin
  OK := TRUE;
  WasOK := TRUE;

  NumCrashes := 0;

  for j := 1 to 3 do
    BlockOK[j] := TRUE;

  BlockNextSwitchTime[1] := Weibull(T1, nu);
  BlockNextSwitchTime[2] := Weibull(T1, nu);
  BlockNextSwitchTime[3] := Norm(m, sigma);
  end;// with

// main loop
repeat

  with Device do
    begin

    // check device blocks
    for j := 1 to 3 do
      begin
      if BlockOK[j] and (t > BlockNextSwitchTime[j]) then        // simulate block crash
        begin
        BlockOK[j] := FALSE;
        BlockNextSwitchTime[j] := BlockNextSwitchTime[j] + Expon(mu);                     // recovery time
        end;// if
      if (not BlockOK[j]) and (t > BlockNextSwitchTime[j]) then  // simulate block recovery
        begin
        BlockOK[j] := TRUE;
        if j = 3 then
          BlockNextSwitchTime[j] := BlockNextSwitchTime[j] + Norm(m, sigma)                 // operation time
        else
          BlockNextSwitchTime[j] := BlockNextSwitchTime[j] + Weibull(T1, nu);               // operation time
        end;// if
      end;// for j...

    end;// with

  // check whole device
  CheckOK(Device);

  if t = tOut then
    begin
    if Device.NumCrashes > 0 then
      begin
      Series1.AddXY(log10(t), Device.TotalOKTime / Device.NumCrashes);
      Series2.AddXY(log10(t), (t - Device.TotalOKTime) / Device.NumCrashes);
      end;

    tOut := tOut * 10;
    end;

  tOld := t;
  t := t + 10;

until t > STOP_TIME;


Caption := Caption + ' - Коэффициент готовности: ' + FloatToStr(Device.TotalOKTime / STOP_TIME);
  
end;

end.