A Scalable Interconnection Network Architecture for Petaflops Computing

Extrapolating technology advances in the near future, a computer architecture capable of petaflops performance will likely be based on a collection of processing nodes interconnected by a high-performance network. One possible organization would consist of thousands of inexpensive, low-power symmetric multiprocessor (SMP) nodes. Each node will inject data into the interconnection network at a very large rate and consequently, the interconnect scheme is one of the most crucial design issues affecting system performance. This paper describes the 2D simultaneous optical multiprocessor exchange bus (2D SOME-Bus) which has the potential to become the basis of a high-end computer architecture capable of petaflops performance. It consists of N horizontal, N vertical 1D SOME-Bus networks, and N ² nodes. Each node is connected to one horizontal and one vertical 1D SOME-Bus. Each of N nodes connected to one 1D SOME-Bus has a dedicated broadcast channel and an input channel interface based on an array of N receivers monitoring all N channels and allowing multiple simultaneous broadcasts. In the 2D SOME-Bus, messages being broadcast on one Bus can be broadcast in a cut-through manner on one or more Buses in the other dimension. This paper describes the optoelectronic devices and technology which make the 2D SOME-Bus possible, and the network interface organization. It also presents simulation results which compare the performance of the 2D SOME-Bus, the 1D SOME-Bus, the crossbar and the torus under the message-passing paradigm.     

Fault-tolerant distributed shared memory on a broadcast-based architecture

Due to advances in fiber-optics and VLSI technology, interconnection networks that allow multiple simultaneous broadcasts are becoming feasible. Distributed-shared-memory implementations on such networks promise high performance even for applications with small granularity. This paper presents the architecture of one such implementation, called the simultaneous optical multiprocessor exchange bus, and examines the performance of augmented DSM protocols that exploit the natural duplication of data to maintain a recovery memory in each processing node and provide basic fault tolerance. Simulation results show that the additional data duplication necessary to create fault-tolerant DSM causes no reduction in system performance during normal operation and eliminates most of the overhead at checkpoint creation. Under certain conditions, data blocks that are duplicated to maintain the recovery memory are utilized by the underlying DSM protocol, reducing network traffic, and increasing the processor utilization significantly.     

The performance of parallel matrix algorithms on a broadcast‐based architecture

Due to advances in fiber‐optics and very large scale integration (VLSI) technology, interconnection networks which allow multiple simultaneous broadcasts are becoming feasible. This paper summarizes one such multiprocessor architecture called the Simultaneous Optical Multiprocessor Exchange Bus (SOME‐Bus). It also presents enhancements to the network interface and the cache and directory controllers which support cache block combining, capture and prefetch, and allow complete overlap of processing time with the communication time due to compulsory misses. The paper uses two fundamental matrix algorithms to characterize the impact of each enhancement on performance. Cache miss analysis and results from the execution of these programs on a SOME‐Bus simulator show that block capture and prefetch combined with an effective block replacement policy succeed in significantly reducing the miss rate due to compulsory misses as the cache size increases, while a similar increase of cache size in traditional architectures leaves the miss rate due to compulsory misses unaffected. Copyright © 2005 John Wiley & Sons, Ltd.     

Message waiting time with interdependent uniform transfer and processing times

This paper examines the model of a computer system where messages arrive continuously and are served by receiving some amount of processing. Both transfer and processing times depend on the length of the message, resulting in a degree of interdependence between them. Here we assume that transfer times have uniform marginal density and examine different types of joint density functions of interarrival and service times. We develop and solve a relationship between system times of successive messages, and we use the solution to develop the system state probabilities of the arrival instants.     

Analysis of a sampling technique applied to biological images

This correspondence examines the classification potential of two techniques based on spiral sampling of binary images of zooplankton. Image pixels are rearranged into a one-dimensional sequence by selecting samples in a spiral manner starting from the edge of the image and proceeding toward the center. The properties of this sample sequence are examined by Fourier transform and correlation techniques, using images from six major zooplankton categories of varying orientation and size. The ability of features extracted from spiral sequences to classify zooplankton samples, and their classification accuracy are investigated.     

Prediction of the Mould-Free Shelf Life of Muffins

In this article, the effect of commonly used ingredients in muffins (sugar, glycerol, potassium sorbate, acidic agent, salt), with and without ethanol surface spraying and pasteurization on the shelf life, was examined. Citric acid, sodium diacetate, and tartaric acid were used as acidic agents. The investigation was based on a statistical design of experiments. Using simple first order factorial designs, reliable models were constructed revealing the effects of the selected ingredients, and their interactions on the shelf life. The effectiveness of preservation ranked high to low as: (combination of citric acid, potassium sorbate, ethanol, and pasteurization), (combination of citric acid, potassium sorbate, and ethanol), (combination of citric acid and potassium sorbate), (combination of sodium diacetate and potassium sorbate), (combination of tartaric acid and potassium sorbate).     

Multiparametric investigation of mould‐free shelf life of bread via factorial design

The investigation of a complex process, such as the bread making process, can be greatly favored by the approach of statistical design of experiments. Using simple first order factorial designs, reliable models were constructed investigating the effects of salt, sugar, sorbic acid, calcium propionate, vegetable fibers, fat and emulsifier on the shelf life of bread (optimization parameter). These effects were in general linear. An exception was observed in the case of use of calcium propionate where an interaction between salt and sugar was determined. The effects of all significant factors on optimization parameter were reasonable. Sorbic acid and calcium propionate proved to be more effective preservatives than salt and sugar by an order of magnitude. Antifungal efficiency of sorbic acid was found to be about three times that of calcium propionate. Prolongation of shelf life reached 117% for sorbic acid and 63 % for calcium propionate, when salt and sugar were fixed to their basic levels. Vegetable fibers had a detrimental effect on shelf life greatly decreasing it by as much as 65 % of the control samples (without fibers). Addition of fat and emulsifier in the dough showed a slightly negative effect on the mould‐free shelf life of bread.     

Prolongation of the microbial shelf life of wrapped part baked baguettes

The effect of some factors, such as ethanol content, type of modified atmosphere packaging and UV radiation dose, on the mould free shelf life of wrapped part‐baked baguettes has been investigated in comparison with the conventional chemical preservatives as calcium propionate and potassium sorbate. Ethanol content, ranging between 0.5‐15% by weight, can cause a significant increase in the mould free shelf life up to 1050%, when its percentage reaches 1.5% by weight of part baked wrapped baguette. Modified atmosphere packaging in polyethylene‐polyamide‐polyethylene vinyl alcohol (PA/EVOH/PE) bags can lead to an increase of at least 1400% and it is more effective at lower temperature of storage. The UV radiation treatment (32 kGy) increases the shelf life by 100 %. In contrast, the addition in the dough 0.15% of calcium propionate or potassium sorbate by flour weight improves the shelf life by 26% and 106% respectively.     

Synergistic effect of chemical preservatives with ethanol on the microbial shelf life of bread by factorial design

The shelf life, particularly the mould-free shelf life (MFSL) of bread, was evaluated either by adding a conventional chemical preservative or by spraying the surface of bread, in which a chemical preservative was added. As bread making is a complex process and bread is a multicomponent system, the investigation was based on statistical design experiments. Using first-order factorial designs, reliable models were constructed, revealing the effects of some common ingredients of bread (such as salt, sugar, glycerol, potassium sorbate, calcium propionate) and their interactions on the MFSL (optimisation parameter) with and without ethanol surface spraying. The effectiveness of preservation was ranked as potassium sorbate + ethanol > calcium propionate + ethanol > potassium sorbate > calcium propionate. Ethanol addition led to MFSL prolongation of 43.5% and 38.5% compared with MFSL of potassium sorbate and calcium propionate, respectively, when all the factors were fixed to their basic levels.