The information-theoretic capacity of discrete-time queues

The information-theoretic capacity of continuous-time queues was analyzed recently by Anantharam and Verdu (see ibid. vol.42, p.4-18, 1996). Along similar lines, we analyze the information-theoretic capacity of two models of discrete-time queues. The first model has single packet arrivals and departures in a time slot and independent packet service times, and is the discrete-time analog of the continuous-time model analyzed by Anantharam and Verdu. We show that in this model, the geometric service time distribution plays a role analogous to that of the exponential distribution in continuous-time queues, in that, among all queues in this model with a given mean service time, the queue with geometric service time distribution has the least capacity. The second model allows multiple arrivals in each slot, and the queue is modeled as serving an independent random number of packets in each slot. We obtain upper and lower bounds on the capacity of queues with an arbitrary service distribution within this model, and show that the bounds coincide in the case of the queue that serves a geometrically distributed number of packets in each slot. We also discuss the extremal nature of the geometric service distribution within this model     

Efficient scheduling of transmissions in optical broadcast networks

All-optical networks (AONs) with a broadcast-star based physical topology offer the possibility of transmission scheduling to resolve channel and receiver conflicts. This paper considers the problem of scheduling packet transmissions in a wavelength-division multiplexed (WDM) optical network with tunable transmitters and fixed-tuned receivers. The scheduling problem is complicated by tuning latency, a limited number of channels, and arbitrary traffic demands. We first analyze scheduling all-to-all packet transmissions and obtain a new lower bound for the schedule length. The lower bound is achieved by an algorithm proposed by Pieris and Sasaki (1994). We then extend the analysis to the case of arbitrary traffic demands and obtain lower bounds for the schedule length. Two constructions for scheduling algorithms are provided through list scheduling and multigraphs. The upper bounds so obtained not only provide performance guarantees with arbitrary demands, but also nearly meet the lower bound in simulations     

Parallel-machine rescheduling with machine disruptions

In this study we consider a rescheduling problem on identical parallel machines. The rescheduling is undertaken because of a period of unavailability on one of the machines. We consider the total flow time as an efficiency measure and stability is gauged in terms of the number of jobs processed on different machines in the original and new schedules. We show that all efficient schedules with respect to efficiency and stability measures can be generated in polynomial time.     

Optical CDMA via temporal codes

The authors provide an analysis of the performance of optical orthogonal codes in an optical code division multiple access (CDMA) network by considering the probability distribution of the interference patterns. It is shown that the actual performance is close to a previous estimate. A less structured temporal code in which the code words are allowed to overlap at two pulse positions is also considered. The bit error probability for this class of codes is obtained for two cases: with and without optical hard-limiting at the receivers. It is shown that this code may increase the number of users in the network considerably without a significant loss in the performance     

THE DETECTION OF SOYBEAN FLOUR IN COCOA POWDER

Protein analysis is evaluated for determining the presence and content of soybean flour which is used as an adulterant in cocoa powder. The coefficients of the determination were significantfor estimating the level of adulteration. A protein scale is developed for quantitative measurement of soybean flour in cocoa powder.     

Scheduling parallel machines to minimize weighted flowtime with family set-up times

We describe and evaluate several branch-and-bound algorithms for an identical parallel machine scheduling problem with family set-up times and an objective of minimizing total weighted flowtime. The algorithms differ by choice of lower bound method. Computational results suggest conditions favourable to a particular algorithm as well as the range of problem sizes that can be optimally solved in reasonable CPU time.     

Evaluation of the main parameters affecting seismic performance of the RC buildings

Low and mid-rise reinforced concrete (RC) buildings consist of an important portion of the building stock in many earthquake prone countries. Therefore understanding their seismic behaviour is important for mitigation studies. This study aims to evaluate how much and when; seismic code, number of stories, concrete strength, amount of transverse reinforcement and infill-wall contribution parameters are important for seismic performances of RC buildings. Seismic performances of the models reflecting different cases are determined for different performance levels and seismic loading conditions. Based on the considered values of the parameters, it is concluded that: modern code specifications and higher transverse reinforcement 50%, the concrete strength up to 66%, infill-walls 15% and number of story 55% increase the seismic performance for life safety level. Evaluations on the effect of the considered parameters for different performance levels and seismic loadings in relation with other parameters are also given in this paper.     

EFFECT OF BLANCHING ON STORAGE STABILITY OF HAZELNUT MEAL

Influence of blanching on storage stability of hazelnut meal was investigated under accelerated storage conditions. Meals were obtained from unblanched and blanched hazelnut kernels, and stored at a relative humidity of 60% at 30C for 50 days. Total free fatty acid content, concentrations of individual free fatty acids, peroxide value and oil stability index were measured in the hazelnut meal samples during storage. No significant difference was found between peroxide values of the samples, however, the values of both samples increased during storage time. The concentrations of free fatty acids increased because of the activity of lipase in both meals, but the levels were lower in the blanched sample. Oil stability index of the unblanched sample was lower than that of the blanched sample. Blanching treatment was found to improve the oxidative stability of hazelnut meal, possibly because of partial inactivation of deteriorative enzymes.

PRACTICAL APPLICATIONS

Hazelnut meal is a product obtained from hazelnut which is used as an ingredient in various food products. Hazelnut meal is more prone to degradation and quality loss during storage via oxidation compared with the whole counterpart. Stability of whole hazelnut has been studied to a great extent in the literature, but there is a scarcity of information regarding stability of processed hazelnut. In addition, there is no information in the literature about the amount of individual free fatty acids in hazelnut where the amounts of total free fatty acids have been reported extensively. This study provides data for quality and stability of hazelnut meal during storage which could be used by the food industry.     

Dynamic analysis of rail vehicle axle

In this paper, in order to obtain the dynamic forces on the passenger coach axle, a full rail vehicle model with 19-dof (degrees of freedom) has been considered. For a specific example, the variations of these dynamic forces with velocity of the passenger coach, suspension characteristics and way conditions have been examined. Dynamic forces found in the resonance regions at the range of 2–5 m/s (7.2–18 km/h) has been discussed. Theoretical results obtained for the dynamic forces have been successfully compared with the experimental results of German Railways (Deutsche Bahn-DB).     

Performance analysis of generalized selection combining withswitching constraints

Generalized selection combining (GSC), in which the best L_c out of L independent diversity channels are linearly combined has been previously proposed and analyzed for Rayleigh fading channels. GSC is a less complex alternative to maximal ratio combining (MRC) that provides a performance gain over traditional selection combining (SC). Both MRC and SC are special cases of CSC, with L_c=L and L_c=1, respectively. We show that CSC also dramatically reduces the impact of switching rate constraints, whereby a selection must be held for the duration of a packet