Resource Management for Fault Tolerant Path Structures in SONET Ring Networks

There is growing interest on the part of networkoperators in the ability to analyze the availability ofpath implementations in their networks and to providevarious grades of assured service availability to customers. The calculation of availabilityis, however, considerably more complex in today's SONETring-based networks than in prior point-to-pointsystems. This is due both to the active protection nature of the rings and their dual-redundantinterconnect strategies. We show that there is also morethan one option for dual-ring interconnection and thata minimum cost high availability path implementation will generally involve a mixture ofmatched-node and explicitly dual fed treatments. Wedevelop an economic comparison of dual feeding (df) andmatched nodes (mn) in terms of the resource consumptionof each scheme and show that the choice can bemade on an individual ring-by-ring basis with a simpledecision criterion. We then develop expressions ofgeneral use for the end-to-end unavailability ofsingle-fed, pure df, mn and mixed df-mn path constructions.These results are a step towards on-line provisioning orpath planning systems that can minimize the pathimplementation cost subject to an assured target level of design availability.     

Strategies for management of connection oriented data sessionsemploying the idle times in cellular telephony

We consider strategies for and performance of a class of connection-oriented data session services that might be supported using only the idle times between telephone calls on the channels of a cellular radio system. Two types of service are envisaged: a short transaction service and a suspendable data session service. We give expressions for the mean active and inactive times for data sessions and show how session assignment and displacement strategies can shape the distributions of session active and inactive times. We find useful amounts of capacity in the background of telephony systems even at high load, but in its raw form the opportunities for data transmission, and the data session suspension times implied, are rather large-grained for interactive data sessions. However, enforced time-sharing can improve these statistics for interactive data uses. With prioritized session assignment, a number of logical data sessions can be supported providing a range of service characteristics onto which interactive users, mobile fax, paging, navigation, and fleet tracking applications can be mapped in decreasing order of required session availability     

Drop formation at nozzles submerged in quiescent continuous phase:an experimental study with TBP-dodecane and nitric acid system

Solvent extraction is an important process in the nuclear fuel cycle. Tributyl phosphate(TBP) diluted with dodecane is commonly used as a solvent for extracting heavy metals from nitric acid medium. Studies on hydrodynamics of a single drop, which is the smallest mass transfer entity, are required for better understanding of the complex mass transfer and phase separation phenomena that occur in extraction equipment. In this study, drop formation at nozzles is studied using 30% TBP-dodecane as the dispersed phase and dilute nitric acid as the quiescent continuous phase. Experiments are carried out to determine the drop diameter, jetting velocity, drop detachment height and drop detachment time for various dispersed phase velocities, nozzle diameters(1.91, 3.04, and 4.88 mm), and nitric acid concentrations(0.01, 1, 3 N). Drop formation is captured using high-speed imaging, which enables quantification of drop size, onset of jetting, drop detachment height, and drop detachment time. Experimental data are used to propose correlations for predicting drop diameter and minimum jetting velocity. The correlations are found to be very accurate with average absolute relative errors being 5.23 and 2.97%, respectively.     

Rural household energy demand modelling : A case study of Nepal

This paper describes the methodology adopted to arrive at a casual linear multiple regression to estimate and project end-use energy requirements of a rural household of Nepal. The general model developed is capable of estimating and projecting the total end-use energy requirements if eight variables are known. These are: standard population, household expenditure, agricultural commodity, number of livestock, number of cookstoves, area covered by housing, topography and forest accessibility condition, of a particular village. The method has been applied to estimate primary energy requirements in the household sector of a few surveyed villages typical of Nepal's different physiographical regions. Total useful energy is estimated considering the end-use efficiency of the devices employed for specific end-use activities. Relevance of the socio-economic variable for estimating end-use energy requirements for different villages varies according to the availability, price and choice of specific fuels for different end-use activities.     

Characterization of pyruvate decarboxylase genes from rice

The pdc1 gene encoding pyruvate decarboxylase has been isolated and sequenced from an IR54 rice genomic library. In contrast to a previously isolated intron-less rice genomic pdc, pRgpdc3, this gene contains five intervening introns in the coding region and corresponds to a cDNA clone, pRcpdc1, isolated from an IR54-cDNA library constructed from anaerobically-induced mRNAs. Comparison of the deduced amino acid sequence of this gene with that of the rice pdc2 and pdc3 showed 88% and 89% similarity, and 78% and 79% identity, respectively. Southern blots indicated that more than three genes constitute the pdc gene family in rice. pdc1 is highly inducible under anaerobic conditions. Rice pdc2 is also inducible by anoxia but to a much lesser extent than pdc1.     

Molecular Cloning and Expression of Goat (Capra hircus) Prochymosin in E.coli

In the present investigation, goat prochymosin cDNA was cloned and characterized by sequence analysis. The prochymosin cDNA spanned 1101 nucleotides and was predicted to code for 365 amino acid with a proregion of 42 amino acid. The goat prochymosin cDNA revealed a high degree of homology with respect to nucleotide and amino acid sequence with corresponding to NCBI sequence to goat chymosin at the 99% and 98% levels, respectively, followed by sheep with 98% homology at both the nucleotide and amino acid levels. The least homology of 76% at the nucleotide level and 69% at the amino acid level was observed for the rat sequences. The cDNA fragment containing goat prochymosin was then subcloned in to pET43.1a(+) and expressed as a NusA fusion protein in E.coli which showed low level of milk clotting activity after activation at acid pH.     

A proposal to use the justification bits of a DS-3 stream forsignaling

The derivation of a signaling channel using the redundant justification bits in the DS-3 signal is proposed to remedy the DS-3 networks lack of overhead for support of intelligent network functions. In the DS-3 network each frame of 680 time slots contains one time slot (a stuff slot) that can be used to either transmit information from an appropriate tributary or to fill out the format. In the latter case, the redundant time slot can be used to carry auxiliary signaling information. It is proposed to use the random sequence of all these redundant time slots as the basis for the new signaling channel. It is shown that the information capacity of the resulting channel is 23 kb/s. This capacity is more than sufficient to implement the network management techniques in DS-3 networks and has the advantage of complete transparency to the existing payloads and to existing or new equipment not intended to process such signaling channels     

The Stanmore total hip arthroplasty. A 15- to 20-year follow-up study

An ongoing study was made of 804 primary Stanmore total hip prostheses implanted in 839 patients between 1973 and 1991. The earliest surviving implants were brought back for radiologic and clinical review in 1995 at an average of 17 years after surgery. The remainder of the patients still living were sent a questionnaire to assess their current status. Survivorship was 95% at 10 years, 85% at 15 years, and 73% at 20 years. The average Merle d'Aubigné-Postel score was excellent up until 14 years. Patient satisfaction remained high until 22 years. Overall, 10% of the prostheses had failed. The results of this study suggest that the Stanmore prosthesis is capable of producing satisfactory long-term results that compare favorably with those of other cemented prostheses.     

Precision time-transfer in transport networks using digitalcross-connect systems

A technique for precise synchronization of the time-of-day clocks in networks of digital cross-connect systems (DCSs) is described. This method is intended to enhance the performance of reconfigurable transport networks and is specifically devised to exploit the fine time resolution of the carrier signals to which a DCS has direct access. The resulting scheme is a master-slave, multisite, implicitly delay compensated, nonhierarchical time-transfer method with a theoretical precision of one bit time at the carrier rate. In practice, precision is limited by transmission span delay asymmetries but residual time errors of under 1 μs are predicted. The method is intended for n/ n space-switching DCS, but other DCS properties can be accommodated. Requirements for DCS equipment design are given, including a generic circuit module for DCS hardware support of the time transfer function. The proposed method applies to DS-3 networks or synchronous optical networks and requires no change in the standards. Measurement or improved estimation of characteristic span delay asymmetries is recommended to refine the preliminary performance estimate