DECLARE SUB READATA (VIT() AS SINGLE, TS AS SINGLE, NDATA AS INTEGER) DECLARE SUB OSCIL (FREQU AS SINGLE, VIT() AS SINGLE, ACC() AS SINGLE, TS AS SINGLE, DZETA AS SINGLE, NDATA AS INTEGER) '****************************************************************** '* Calculate the acceleration of the sismic mass of an elementary * '* oscillator (1 degree of freedom), the basis of which is submit-* '* ted to a given speed, VIT(t). The input signal VIT is digitali-* '* zed with a constant time step, TS. The table VIT(I) contains * '* NDATA speed values. * '* * '* Quick Basic Version By J-P Moreau, Paris * '* (in simple precision). * '* -------------------------------------------------------------- * '* SAMPLE RUN: * '* * '* Read data from file speed.dat * '* Write results to file response.txt. * '****************************************************************** DEFINT I-N NMAX = 2048 'Maximum number of points of input signal DIM ACC(NMAX), VIT(NMAX) AS SINGLE DIM NDATA AS INTEGER DIM DZETA, F0, FMAX, T, TBEGIN, TEND, TS AS SINGLE OPEN "speed.dat" FOR INPUT AS #1 OPEN "response.txt" FOR OUTPUT AS #2 PRINT #2, PRINT #2, " Mass Response to speed(T) at Basis" PRINT #2, F0 = 250!: DZETA = .05 ' Frequency of oscillator PRINT #2, " FREQUENCY OF oscillator: " + STR\$(F0) + " HERTZ" PRINT #2, ' rod damping PRINT #2, " DAMPING OF oscillator: " + STR\$(DZETA) PRINT #2, ' READ MEASUREMENTS READATA VIT(), TS, NDATA CLOSE #1 TBEGIN = 0: TEND = TBEGIN + (TS * (NDATA - 1)) FMAX = .5 / TS PRINT #2, " NYQUIST FREQUENCY:" + STR\$(FMAX) ' Compute mass response OSCIL F0, VIT(), ACC(), TS, DZETA, NDATA PRINT #2, PRINT #2, " TIME (S) MASS ACC. (M/S2) " PRINT #2, " ------------ -----------------" T = TBEGIN FOR I = 1 TO NDATA PRINT #2, " " + STR\$(T); PRINT #2, TAB(18); ACC(I) T = T + TS NEXT I CLOSE #2 CLS PRINT PRINT " Results in file reponse.txt..." PRINT END 'of main program SUB OSCIL (FREQU AS SINGLE, VIT() AS SINGLE, ACC() AS SINGLE, TS AS SINGLE, DZETA AS SINGLE, NDATA AS INTEGER) '************************************************************* '* This subroutine calculates the acceleration of the sismic * '* mass of an elementary oscillator (1 degree of freedom), * '* the basis of which is submitted to a given speed, VIT(t). * '* The input signal VIT is digitalized with a constant time * '* step, TS. The table VIT(I) contains NDATA speed values. * '* --------------------------------------------------------- * '* INPUTS: * '* FREQU........: eigen frequency of oscillator * '* VIT..........: input speed signal of basis VIT(t) * '* TS...........: time step of signal (constant) * '* DZETA........: reduced damping factor * '* NDATA........: number of points of signal * '* OUTPUT: * '* ACC..........: table containing acceleration res- * '* ponse of oscillator (NDATA points) * '* * '* VB 2008 Express Version By J-P Moreau, Paris. * '************************************************************* DIM ARG, DELTA, EXPA, GOMEGA, OMEGA, OMEGA2, PI, T AS SINGLE DIM COSARG, Q0, Q1, Q2, QSI, R0, R1, R2, R3, SINARG AS SINGLE DIM XPN, XPNP1, YPN, YPNP1, YPPN, YPPNP1 AS DOUBLE PI = 4! * ATN(1!) T = TS OMEGA = 2! * PI * FREQU OMEGA2 = OMEGA * OMEGA DELTA = SQR(1 - DZETA * DZETA) EXPA = EXP(-OMEGA * DZETA * T) GOMEGA = OMEGA * DELTA ARG = GOMEGA * T SINARG = SIN(ARG) COSARG = COS(ARG) QSI = DZETA / DELTA Q0 = (COSARG - QSI * SINARG) * EXPA Q1 = OMEGA2 * SINARG / GOMEGA * EXPA Q2 = (1# + (QSI * SINARG - COSARG) * EXPA) / T R1 = SINARG / GOMEGA * EXPA R0 = COSARG * EXPA + DZETA * OMEGA * R1 R2 = (1 - DZETA * OMEGA * T) * R1 / T - COSARG * EXPA R3 = 1 - R1 / T XPNP1 = VIT(1) YPPNP1 = 0 YPNP1 = 0 ACC(1) = Q2 * XPNP1 FOR I = 2 TO NDATA YPN = YPNP1 YPPN = YPPNP1 XPN = XPNP1 XPNP1 = VIT(I) YPPNP1 = Q0 * YPPN + Q1 * (XPN - YPN) + Q2 * (XPNP1 - XPN) ACC(I) = YPPNP1 YPNP1 = R0 * YPN + R1 * YPPN + R2 * XPN + R3 * XPNP1 NEXT I END SUB SUB READATA (VIT() AS SINGLE, TS AS SINGLE, NDATA AS INTEGER) '------------------------------------------------ 'Read ndata: number of points of input signal ' ts: sampling duration of signal in sec. ' ACC(i): Table with ndata acceleration values '------------------------------------------------ DIM TEMP AS SINGLE INPUT #1, NDATA PRINT #2, STR\$(NDATA) + " POINTS READ." INPUT #1, TS PRINT #2, " SAMPLING DURATION:" + STR\$(TS) FOR I = 1 TO NDATA INPUT #1, TEMP, VIT(I) NEXT I END SUB