Hybridizing the harmony search algorithm with a spreadsheet ‘Solver’ for solving continuous engineering optimization problems

In this article, a hybrid global–local optimization algorithm is proposed to solve continuous engineering optimization problems. In the proposed algorithm, the harmony search (HS) algorithm is used as a global-search method and hybridized with a spreadsheet ‘Solver’ to improve the results of the HS algorithm. With this purpose, the hybrid HS–Solver algorithm has been proposed. In order to test the performance of the proposed hybrid HS–Solver algorithm, several unconstrained, constrained, and structural-engineering optimization problems have been solved and their results are compared with other deterministic and stochastic solution methods. Also, an empirical study has been carried out to test the performance of the proposed hybrid HS–Solver algorithm for different sets of HS solution parameters. Identified results showed that the hybrid HS–Solver algorithm requires fewer iterations and gives more effective results than other deterministic and stochastic solution algorithms.     

Correction to: Network Functions Virtualization for Mobile Core and Heterogeneous Cellular Networks

Wireless Personal Communications -     

Determination of hepatic zinc content in chronic liver disease due to hepatitis B virus

BACKGROUND/AIMS: Zinc is an essential, mostly intracellular, trace element which participates in many physiologic mechanisms. Some liver functions like urea formation require the presence of zinc; thus the determination of hepatic zinc content may contribute to the understanding of probable zinc-related clinical consequences of chronic liver disease. In this study, we aimed to determine the hepatic zinc concentrations in patients with chronic liver disease due to the Hepatitis B virus and to ascertain the relationship between the severity of liver disease and hepatic zinc content, if one in fact exists. METHODOLOGY: A total of 99 HBsAg positive subjects were included in the study. We performed a liver biopsy on all subjects. Hepatic zinc concentrations were determined by atomic absorption spectrophotometry. RESULTS: The liver biopsies were normal in 25 subjects. There were 33 chronic active hepatitis (CAH), 34 cirrhosis and 7 chronic persistent hepatitis (CPH) patients in the study group. In the control group, CAH, cirrhosis and CPH groups, the mean liver zinc concentrations were 3.83 +/- 1.86, 1.86 +/- 0.92, 1.14 +/- 0.68 and 3.74 +/- 1.81 mumol/g dry weight, respectively. Hepatic zinc in the CAH and cirrhosis groups were lower than that of the control group (p < 0.05). We also found that liver zinc in the cirrhosis group was lower than in the CAH group (p < 0.05). CONCLUSION: According to these results, as the severity of liver damage increases, the hepatic zinc concentration decreases. Therefore, it can be suggested that zinc supplementation may improve hepatic encephalopathy by increasing the efficiency of the urea cycle.     

Structured Peer-to-Peer Real Time Video Transmission over Vehicular Ad Hoc Networks

Video communication over Vehicular Ad Hoc Networks (VANET) has several applications such as road safety, commercial advertisements and on-road entertainment. In this paper we present a structured peer-to-peer (P2P) network designed for the distribution of live-content, with low bandwidth consumption, within a VANET. This P2P network is modelled using a media distribution graph. The implementation of a structured network allows a peer to schedule consecutive data chunks produced by the media source by means of a scheduling algorithm. In our analysis we obtain a bound for the maximum delay between the media source and any of the peers of the network and the buffer size needed to allow consecutive scheduling. We study a type of media distribution graph and we calculate its order and diameter, which means that under stable conditions we can ensure certain quality-of-service parameters. The results of simulation over NS2 show the fitness of the mathematical analysis.     

Difference equation representation of chirp signals andinstantaneous frequency/amplitude estimation

We present a time-varying coefficient difference equation representation for sinusoidal signals with time-varying amplitudes and frequencies. We first obtain a recursive equation for a single chirp signal. Then, using this result, we obtain time-varying coefficient difference equation representations for signals composed of multiple chirp signals. We analyze these equations using the skew-shift operators. We show that the phases of the poles of the difference equations produce instantaneous frequencies (IF), and the magnitudes are proportional to the ratio of successive values of the instantaneous amplitudes (IA). Then algorithms are presented for the estimation of instantaneous frequencies and instantaneous amplitudes for multicomponent signals composed of chirps using the difference equation representation. The first algorithm we propose is based on the skew-shift operators. Next we derive the conditions under which we can use the so-called frozen-time approach. We propose an algorithm for IF and IA estimation based on the frozen-time approach. Then we propose an automatic signal separation method. Finally, we apply the proposed algorithms to single and multicomponent signals and compare the results with some existing methods     

Efficient and Scalable Routing Algorithms for Collective Communication Operations on 2D All-Port Torus Networks

Collective Communication Algorithms for 2D torus networks have been investigated quite extensively in the literature and two broad approaches, namely direct methods and indirect (message combining) methods are recognized in the field. While direct methods minimize the volume of data, the indirect methods reduce the number of message start-ups. Consequently, either a suite of algorithms must be employed for efficiency over a wide range of message lengths and communication operations or algorithms should be able to adapt themselves to the current case, possibly by switching between direct and indirect routing modes as appropriate. In this paper, we propose adaptive routing algorithms for all-port, wormhole routed, synchronous, 2D torus networks optimized for one-to-all broadcast,  gossiping and complete exchange collective communication operations. The proposed algorithms employ completely-connected subnetworks where complete exchange amongst the nodes in the subnetwork can be accomplished in one step only. Combined with suitable 2D plane tiling techniques, the proposed algorithms share the same set of primitive operations and yield superior performance compared to previously proposed methods, either pure or hybridized.     

A parallel implementation of Strassen’s matrix multiplication algorithm for wormhole-routed all-port 2D torus networks

A new parallel implementation of Strassen’s matrix multiplication algorithm is proposed for massively parallel supercomputers with 2D, all-port torus interconnection networks. The proposed algorithm employs a special conflict-free routing pattern for better scalability and is able to yield a performance rate very close to the theoretical bound for many practical network and matrix sizes. It effectively scales up to very large networks typically containing hundreds-of-thousands processors where petaflop or exaflop processing rates are sought.