تحقیقات حدیث میں پروفیسر جوزف شاخت کی طرز تحقیق کا تنقیدی جائزہ

In general, the results of research studies conducted by Professor Joseph Schacht and his fellows on criticism of Ahadith are contradictory with the results of Muslim Scholars. Muslim Scholars, point of view is that Muhaddithin have opposed, with full power, the condemnable tries for fabrication of Ahadith. Valuable principles for the identification of authentic and unauthentic traditions were the result of the struggles done by Muhaddithin. With the help of these principles the categorization of Ahadith came in to practical. Professor Joseph Schacht argues that the material presented as Ahadith and Sunna of Prophet by Muslim scholars is the production of later times. According to his point of view, there is no authentic hadith in the bulk of traditions and if assumed that there are few authentic, they are also mixed up with unauthentic and there is no possibility of identification of authentic one. This study is a try to identify the mistakes of his research approach.

Adaptive Simultaneous Multipath Transmission Schemes

The increase in the availability of multimode devices for ubiquitous network ac- cess and the need for larger bandwidth create thrust for utilization of simultaneous network connections. Unfortunately, the standard transport layer protocols like the transmission control protocol (TCP) and user datagram protocol (UDP) have architectural constraints due to which an Internet application can use only one interface at a time. The stream control transmission protocol (SCTP) provides support for concurrent multipath transfer (SCTP-CMT). Aggregated performance is analyzed with a number of experiments to measure the aggregated throughput of SCTP-CMT by using a very popular network simulator, NS-2. It is observed that the aggregated throughput is about 20% of the available aggregated band- width. The signi cant reduction in the aggregated throughput demands a careful scrutinization of its reasons. After carefully analyzing and carrying out some further experiments, it is di- agnosed that non-di erentiation of missing packets into intra and inter-path, usage of traditional congestion window management for these missing packets and using static fast retransmit threshold which is independent of available receiver bu er space, are the main reasons for the aggregated throughput degradation. Simulta- neous multipath transmission (SMT) schemes are proposed to handle the above mentioned issues with the intention to increase aggregated throughput by avoid- ing Rbuf blocking problem and e cient utilization of available Rbuf space. SMT- modi ed fast retransmit (SMT-MFR) and SMT-adaptive modi ed fast retransmit (SMT-AMFR) schemes are formulated for SCTP. To analyze the SMT-MFR in realistic network environments, a number of simulation scenarios are carried out. The initial results revealed that SMT-MFR has overcome Rbuf blocking with im- provement in aggregated throughput ranging from 164% to 72.4% (from normal to worst scenario respectively). SMT- MFR is composed of two sender side modules, i.e., inter-path missing packet di erentiation (IMPD) and multihomed congestion control (MCC). The IMPD module di erentiates the missing packets according to its cause of missing such as, packet missing due to network congestion or due to multiple path e ects. The MCC mechanism triggers the fast retransmit event with respect to the cause of the missing packet. The SMT-MFR has successfully over- come the Rbuf blocking problem, abnormal congestion window (cwnd) reduction and has improved the aggregated throughput.