3,650 research outputs found
Armenian Alphanumerical Notation on a 14th century Iranian Astrolabe found in Fez
I am indebted to professor D. A. King for having brought to my attention the pictures of an astrolabe (#2710), probably of iranian origin, that was made by Muhammad Ibn
Adaptive algorithms for improving the throughput in an indoor mobile s-aloha ds-cdma system
This paper presents a novel Adaptive DSCDMA
Slotted-ALOHA packet random access scheme
with transmitter-based spreading codes for mobiles. It
is aimed at improving the throughput and message
delay delivery when traffic load values below the
saturation point of the conventional DS-CDMA
Slotted-ALOHA system are sensed in the channel. For
this purpose, one Mobile and two Base Station assisted
algorithms are envisaged to control the change of the
transmission rate according to the traffic load. These
algorithms revealed that the optimum behavior,
obtained using a Markov Chain model, may be almost
reached at a low complexity cost.Peer ReviewedPostprint (published version
Arabic, Rumi, Coptic, or merely Greek Alphanumerical Notation? The case of a Mozarabic 10th Century Andalusi Manuscript
The aim of this paper is to analyse the notation that appears alongside the Roman numerals in the Latin manuscript MDU-604 of the Capitular Library in Urgell..
Dect architecture proposal for a construction site
A construction site is an specific environment where important propagation related issues
have to be considered. In particular an important problem concerns the coverage of buildings under
construction and therefore continuously changing. The deployment of a DECT system in such scenarios
can not be carried out as usually, by means of DECT base stations linked by cables. Another specific
problem is that no measures can be done prior to decide the best place for the antennas since initially
the building does not exist. In this paper a way to solve both problems is proposed through a specific
system architecture, a propagation model and a combination of software with a CAD tool.Peer ReviewedPostprint (published version
Adaptive schemes for packet data in a ds-cdma environment
This paper presents a novel adaptive DS-CDMA slotted-ALOHA packet random access scheme for improving the throughput of the conventional DS-CDMA slotted-ALOHA system. For this purpose a mobile-assisted algorithm is envisaged to control the change of the transmission rate according to the traffic load. This algorithm revealed that the optimum behavior may be almost reached at a low complexity cost. Moreover, the proposed algorithm was found to be robust to intercell interferencePeer ReviewedPostprint (published version
A mobile controlled algorithm for improving the throughput in a s-aloha ds-cdma system
This paper presents a novel adaptive DS-CDMA slotted-ALOHA packet random access scheme with transmitter-based spreading codes for mobiles. It is aimed at improving the throughput and message delay delivery when traffic load values below the saturation point of the conventional DS-CDMA slotted-ALOHA system are sensed in the channel. For this purpose a mobile assisted algorithm is envisaged to control the change of the transmission rate according to the traffic load. This algorithm revealed that the optimum behavior, obtained using a Markov chain model, may be almost reached at a low complexity cost. Moreover, priorities between mobiles could be easily established. Finally, a traffic model based on a realistic statistical length distribution of the messages illustrates how the delay delivery can be greatly reduced.Peer ReviewedPostprint (published version
An efficient data transmission policy in an integrated voice-data ds-cdma network
CDMA schemes appear to be promising access techniques for coping with the requirements of third-generation mobile systems, mainly because of their flexibility. This paper proposes an adaptive S-ALOHA DS-CDMA access scheme as a method for integrating non-real time (i.e. Internet applications) and real-time (i.e. voice) services, by exploiting the potentials of CDMA under time-varying conditions. The adaptive component terminals autonomously change their transmission rate according to the total (voice+data) channel occupancy, so that the minimum possible data delay is almost always achieved.Peer ReviewedPostprint (published version
Photoionization research on atomic radiation. 3: The ionization cross section of atomic nitrogen
The photoionization cross section of atomic nitrogen was measured between the ionization limit and 432 A. The experimental values are well fitted by those from a calculation of HENRY due to the dipole velocity approximation. A Rydberg series converging to the 5S-state of the ion is clearly identified from the ionization measurements and is shown to ionize
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