اعتناء المستشرقين بالواقدي وكتابه المغازي دراسة تحليلية

Muhammad ibn ‘Umr Al-W฀qid฀ is considered to be one of the most famous early Muslim historians. Despite being disputed among the circle of Muhaddith฀n, he was popular among the early Muslim historians. He got recognition and fame as a historian in the 2nd half of 2nd century of Hijrah. In fact, he was an outstanding historian who introduced new trends in writing and composition of historic narratives. The early Muslim historians cited and quoted Al-W฀qid฀ freely where they needed him without any kind of reluctance. It is well to know that western orientalists pay special attention to AlW฀qid฀ and his book "Al-Magh฀z฀ ". Perhaps it is not due to their biasness or impartiality, but for the excellent work of Al-W฀qid฀. In this regard, they think that Al-W฀qid฀ is more accurate and clear in giving details and judgments about historical events than any other early Muslim historian. Al-W฀qid฀ 's dating of historical events is more acute and correct. He owns what he produces and narrates. Moreover, he seems to be sensitive and aware of consequences of what he writes in his book " Al-Magh฀z฀ ", that is why we see him sometime indulging in some issues extra-ordinarily and proving and disproving what he thinks right or wrong by logical (internal and external) criticism. Al-W฀qid฀ explores historical events and tries to know about root causes of their happening and finally analyzes their consequences. These are some special qualities of Al-W฀qid฀ 's work in the eyes of western orientalists. In this article, I have tried to highlight these aspects of Al-W฀qid฀ 's work from the oriental literature.

Cross-Term Suppression in Wigner Distribution

Wigner Distribution, one of many methods to compute time frequency represen- tation, satisfies large number of mathematical properties and gives optimal energy concentration in time frequency plane. However, Wigner distribution suffers from severe cross-term interference problem, which limits its scope for practical appli- cations. Different modified versions of Wigner distribution have been developed to over- come its cross-term interference problem. Most of these techniques suppresses cross-term on the expense of quality of auto-terms. Schemes that compleltely remove cross-terms without affecting the resolution of Wigner distribution are computationally very expensive. This research proposes a computationally efficient solution to cross-term inter- ference problem based on image processing and fractional filtering. Signal com- ponents are located in time frequency plane using image processing. Fractional filters are then applied to separate signal components. Wigner distribution of separated signal components is computed and added up to obtain cross-term free crisp time frequency representation. Performance of the proposed time frequency representation is evaluated both on synthetic and real life bat signals. One of the most significant application of Wigner distribution is instantaneous frequency estimation of signals. However, Wigner distribution based instantaneous frequency can only be applied to mono-component signal because of its cross- term problem. In this study we extend Wigner distribution based instantaneous frequency estimation scheme to multi-component signals having non-overlapping time frequency representation.