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In 1999, Cheng, Fan, Zheng proposed a method to determin the parameters: the central black hole mass, M, the Doppler factor, δ, the propagation angle of the γ-rays with respect to the symmetric axis of a two-temperature accretion disk, Φ, and the distance (i.e. the height above the accretion disk), d at which the γ-rays are created. In that method, available variability timescales in gamma-ray bands, the absorption effect of a γ-ray and the beaming effect have been taken into account. In this paper, we adopte this method to a larger sample. Our results indicate that, if we take the intrinsic γ-ray luminosity to be λ times the Eddington luminosity, L[SUPin,SUBγ] = λL[SUBEdd.], the masses of the blazars are in the range of (1.5 ∼ 83) × 10[SUP7]M[SUBΘ] (λ = 1.0) or (2.2 ∼ 131) ×10[SUP7]M[SUBΘ] (λ = 0.1), the Doppler factors (δ) lie in the range of 0.17 to 3.72 (λ = 1.0) or 0.25 to 5.33 (λ = 0.1), the angle (Φ) is in the range of 10° to 68° (λ = 1.0) or 10° to 63° (λ = 0.1), and the distance (d) is in the range of 20.5R[SUBg] to 750R[SUBg] (λ = 1.0) or 18R[SUBg] to 680R[SUBg] (λ = 0.1). [ABSTRACT FROM AUTHOR]

In the Oct. of 2000, we observed 10 gamma-ray loud blazars, PKS 0219+428 (3C 66A), PKS 0420-014 (OA129), S5 0716+714, 0754+100 (OT 090.4), 0827+243 (OJ 248), 1652+398 (Mrk 501), 2200+420 (BL Lacertae), 2230+114 (CTA 102), 2251+158 (3C 454.3), and 2344+514, with the 70 cm optical telescope at Abstumani Observatory, Georgia. We found intraday variations in PKS 0420-014, S5 0716+714, BL Lacertae, and CTA 102. A variation of 0.3 magnitude over a time scale of about 3 hours was observed in R band in BL Lacertae on JD 2451827. We did not detected variation from 3C 66A, Mrk 501, 3C 454.3 or 2344+514 during our observational period. For the TeV gamma-ray source 2344+514 no clear variation was detected in an observational period of two weeks. [ABSTRACT FROM AUTHOR]