For decades the global positioning system (GPS) has been the only space geodetic technique routinely used for inter-continental frequency transfer applications. In the past very long baseline interferometry (VLBI) has also been considered for this purpose and the method’s capabilities were studied several times. However, compared to GPS current VLBI technology only provides few observations per...

Sagittarius A*, the ∼ 4 × 106 M⊙ black hole candidate at the Galactic Center, can be studied on Schwarzschild radius scales with (sub)millimeter wavelength Very Long Baseline Interferometry (VLBI). We report on 1.3 mm wavelength observations of Sgr A* using a VLBI array consisting of the JCMT on Mauna Kea, the ARO/SMT on Mt. Graham in Arizona, and two telescopes of the CARMA array at Cedar Flat...

در این مقاله یک مدل ریاضی برای مسئله سیستم تولیدی همکارانه ساخت بر اساس سفارش با رعایت انصاف تخصیص بار‌های تولید طراحی شده است. اهداف اصلی مدل، کمینه‌سازی هزینه‌‌های کل و حداکثر استفاده از منابع به‌منظور عادلانه شرایط عدم­قطعیت کنترل پارامتر‌های غیرقطعی روش برنامه‌ریزی فازی ‌شده نتایج نشان می‌دهد افزایش نرخ عدم‌قطعیت، می­یابد. ازآنجاکه ظرفیت کارخانه‌ها ثابت است، مقدار تقاضا، هر کارخانه نیز می­ی...

The increasing accuracy and growing time span of Very Long Baseline Interferometry (VLBI) observations allow the determination of seasonal signals in station positions which still remain unmodelled in conventional analysis approaches. In this study we focus on the impact of the neglected seasonal signals in the station displacement on the celestial reference frame and Earth orientation paramete...

We investigate the structure and dynamics of the M87 jet based on multi-frequency VLBI observations and MHD jet theories. Millimeter VLBI cores are considered as innermost jet emissions. The jet structure up to ∼ 105 rs is described as a parabolic streamline, indicating the lateral expansion under a confinement by the stratified ISM. Thus, the jet collimation maintains in five orders of magnitu...

The two 5GHz VLBI (Very Long Baseline Interferometry) observations (1996 June and 1997 November) presented in this paper, combined with several former VLBI observations at 8.4GHz and 5GHz, suggest that the radio flares of the blazar PKS 0420−014 can be divided into two classes according to their geometric origins in 5 or 8.4GHz VLBI maps and the properties of light curves. One class of flares, ...

We present a 5 GHz VLBI image of the compact steep spectrum (CSS) quasar 3C287. The source has been one of the candidate precessing CSS sources. Both static features and large structural changes are observed since the earliest VLBI experiments. The overall picture does not seem to support a precessing jet scenario.

A novel approach to deene milliarcsecond scale angular sizes of active galactic nuclei using VLBI visibility data is presented. The \angular size{redshift" relation for a sample of nearly 250 AGN is discussed. The analysis is based on 5 GHz VLBI observations made in the VSOP pre-launch survey and various imaging observations of extremely high redshift quasars.

Same beam VLBI (very long baseline interferometry) observations of the two sub-satellites of SELENE (KAGUYA) are demonstrated for purpose of the precise gravimetry of the Moon. The same beam VLBI contributes a great deal to cancel out the tropospheric and ionospheric delays and to determine the absolute value of the cycle ambiguity by using the multi frequency VLBI method. As a result, the diff...