| 1. |
- Forsberg, Håkan, et al.
(författare)
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Embedded Signal Processing Using Free-Space Optical Hypercube Interconnects
- 2003
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Ingår i: Optical Networks Magazine. - : Springer-Verlag. - 1572-8161 .- 1388-6916. ; 4:4, s. 35-49
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Tidskriftsartikel (refereegranskat)abstract
- The speed and complexity of integrated circuits are increasing rapidly. For instance, today's mainstream processors have already surpassed gigahertz global clock frequencies on-chip. As a consequence, many algorithms proposed for applications in embedded signal-processing (ESP) systems, e.g. radar and sonar systems, can be implemented with a reasonable number (less than 1000) of processors, at least in terms of computational power. An extreme inter-processor network is required, however, to completely implement those algorithms. The demands are such that completely new interconnection architectures must be considered.In the search for new architectures, developers of parallel computer systems can actually take advantage of optical interconnects. The main reason for introducing optics from a system point of view is the strength in using benefits that enable new architecture concepts, e.g. free-space propagation and easy fan-out, together with benefits that can actually be exploited by simply replacing the electrical links with optical ones without changing the architecture, e.g. high bandwidth and complete galvanic isolation.In this paper, we propose a system suitable for embedded signal processing with extreme performance demands. The system consists of several computational modules that work independently and send data simultaneously in order to achieve high throughput. Each computational module is composed of multiple processors connected in a hypercube topology to meet scalability and high bisection bandwidth requirements. Free-space optical interconnects and planar packaging technology make it possible to arrange the hypercubes as planes with an associated three-dimensional communications space and to take advantage of many optical properties. For instance, optical fan-out reduces hardware cost. Altogether, this makes the system capable of meeting high performance demands in, for example, massively parallel signal processing. One 64-channel airborne radar system with nine computational modules and a sustained computational speed of more than 1.6 Tera floating point operations per second (TFLOPS) is presented. The effective inter-module bandwidth in this configuration is 1 024 Gbit/s.
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| 2. |
- Forsberg, Håkan, et al.
(författare)
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Key Issues in Implementing an Optoelectronic Planar Free-space Architecture for Signal Processing Applications
- 2003
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Ingår i: IASTED International Multi-Conference on Applied Informatics. - : IASTED/ACTA Press. - 0889863415 ; , s. 621-629
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Konferensbidrag (populärvet., debatt m.m.)abstract
- In this paper, we deal with the key issues in implementing an optoelectronic architecture suitable for embedded signal processing. The architecture is based on a system concept where free-space optical interconnects and planar packaging technologies make it possible to merge complicated and new parallel computer architectures into planes and to take advantage of many properties of optics. For instance, optical fan-out reduces the hardware cost as well as the all-to-all broadcast time. It is also possible to meet scalability and high bisection bandwidth requirements. The main results show that it is possible to build a 6D hypercube using planar optical substrates.
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| 3. |
- Forsberg, Håkan, 1969-, et al.
(författare)
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Opportunities for Optical Planar Interconnection Technology in Terabit Switches
- 2003
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Ingår i: Proceedings of the IASTED International Conference on Wireless and Optical Communications, July 2-4, 2003, Banff, Canada. - Anaheim; Calgary : ACTA Press. - 0889863741 - 9780889863743 ; , s. 155-164
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Konferensbidrag (refereegranskat)abstract
- To keep up with the explosive growth of world-wide network traffic, large-capacity switches, with switching capacities in excess of several terabits per second, are becoming an essential part of the future. To realize such switches, new architecture concepts must be considered. In this paper, we discuss a technology for terabit switches that combines the advantage of using optical communication in all three spatial dimensions and the benefits of using surface mounted optoelectronic as well as electronic chips. We present three different types of packet-based switch fabrics, all based on the optical planar interconnection technology. We then discuss these in terms of capacity, scalability, and physical size. All three implementations have a single switch plane cross sectional bandwidth exceeding 5 Tbps.
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| 4. |
- Malm, Annika, 1970, et al.
(författare)
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The association of drinking water treatment and distribution network disturbances with Health Call Centre contacts for gastrointestinal illness symptoms
- 2013
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Ingår i: Water Research. - : Elsevier BV. - 0043-1354 .- 1879-2448. ; 47:13, s. 4474-4484
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Tidskriftsartikel (refereegranskat)abstract
- There are relatively few studies on the association between disturbances in drinking waterservices and symptoms of gastrointestinal (GI) illness. Health Call Centres data concerningGI illness may be a useful source of information. This study investigates if there is anincreased frequency of contacts with the Health Call Centre (HCC) concerning gastrointestinal symptoms at times when there is a risk of impaired water quality due to disturbances at water works or the distribution network. The study was conducted inGothenburg, a Swedish city with 0.5 million inhabitants with a surface water source ofdrinking water and two water works. All HCC contacts due to GI symptoms (diarrhoea,vomiting or abdominal pain) were recorded for a three-year period, including also sex, age,and geocoded location of residence. The number of contacts with the HCC in the affectedgeographical areas were recorded during eight periods of disturbances in the water works(e.g. short stops of chlorine dosing), six periods of large disturbances in the distributionnetwork (e.g. pumping station failure or pipe breaks with major consequences), and 818pipe break and leak repairs over a three-year period. For each period of disturbance theobserved number of calls was compared with the number of calls during a control periodwithout disturbances in the same geographical area. In total about 55, 000 calls to the HCCdue to GI symptoms were recorded over the three-year period, 35 per 1000 inhabitants andyear, but much higher (>200) for children
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| 5. |
- Tornevi, Andreas, et al.
(författare)
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Precipitation Effects on Microbial Pollution in a River: Lag Structures and Seasonal Effect Modification
- 2014
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203 .- 1932-6203. ; 9:5
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Tidskriftsartikel (refereegranskat)abstract
- Background: The river Gota Alv is a source of freshwater for 0.7 million swedes. The river is subject to contamination from sewer systems discharge and runoff from agricultural lands. Climate models projects an increase in precipitation and heavy rainfall in this region. This study aimed to determine how daily rainfall causes variation in indicators of pathogen loads, to increase knowledge of variations in river water quality and discuss implications for risk management. Methods: Data covering 7 years of daily monitoring of river water turbidity and concentrations of E. coli, Clostridium and coliforms were obtained, and their short-term variations in relation with precipitation were analyzed with time series regression and non-linear distributed lag models. We studied how precipitation effects varied with season and compared different weather stations for predictive ability. Results: Generally, the lowest raw water quality occurs 2 days after rainfall, with poor raw water quality continuing for several more days. A rainfall event of >15 mm/24-h (local 95 percentile) was associated with a three-fold higher concentration of E. coli and 30% higher turbidity levels (lag 2). Rainfall was associated with exponential increases in concentrations of indicator bacteria while the effect on turbidity attenuated with very heavy rainfall. Clear associations were also observed between consecutive days of wet weather and decreased water quality. The precipitation effect on increased levels of indicator bacteria was significant in all seasons. Conclusions: Rainfall elevates microbial risks year-round in this river and freshwater source and acts as the main driver of varying water quality. Heavy rainfall appears to be a better predictor of fecal pollution than water turbidity. An increase of wet weather and extreme events with climate change will lower river water quality even more, indicating greater challenges for drinking water producers, and suggesting better control of sources of pollution.
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