| 1. |
- Santesson, Sabina, et al.
(författare)
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Airborne Single Cell Chemistry
- 2002
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Ingår i: European Biotechnology News. ; 1:1, s. 39-40
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Tidskriftsartikel (populärvet., debatt m.m.)
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| 2. |
- Almefelt, Lars, 1968, et al.
(författare)
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Exploring Requirements Management in the Automotive Industry
- 2003
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Ingår i: 14th International Conference on Engineering Design Research for Practice - innovative products, processes and organisations.
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Konferensbidrag (refereegranskat)abstract
- This paper presents an empirical study carried out in the automotive industry, with the aim to bring forward new experiences and knowledge on management of requirements in practice. Adopting a qualitative systems approach, and using multiple information sources, the requirements management process during the development of a passenger car cockpit has been mapped out. The logical reconstruction of the requirements management process is complemented with descriptions of associated phenomena, such as important events and attitudes. Findings are presented, analysed and discussed considering also factors underlying observed phenomena.
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| 3. |
- Andersson, Fredrik, 1974, et al.
(författare)
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Computer Based Requirements and Concept Modelling - Information Gathering and Classification
- 2000
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Ingår i: 12th International Conference on Design Theory and Methodology. 2000 ASME International Design Engineering Technical Conferences.
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Konferensbidrag (refereegranskat)abstract
- This paper proposes a requirement and concept model based on a functional decomposition of mechanical systems. It is an object-oriented approach to integrate the representation of the design artefact and the design activity, through the decisions made during the design evolution. The requirements co-evolve simultaneously with the formation of the conceptual layout, through the opportunity to alter between function and physical/abstract solutions. This approach structures the design requirements and concepts in such a way that it supports the ability to document their sources, to allow for validation and verifications of both requirements and design solutions. First, the proposed model is presented from a theoretical viewpoint. Secondly, a methodology for modelling requirements and concepts in an object-oriented fashion is discussed. Finally, the model is implemented in METIS software and tested in a case study of an electric window winder on a truck door.
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| 4. |
- Berglund, Christer, et al.
(författare)
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A note on inter-country differences in waste paper recovery and utilization
- 2002
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Ingår i: Resources, Conservation and Recycling. - 0921-3449 .- 1879-0658. ; 34:3, s. 175-191
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Tidskriftsartikel (refereegranskat)abstract
- Countries worldwide express waste paper recycling targets in terms of recovery and utilization rates. The main purpose of this paper is to identify and analyze the most important determinants of inter-country differences in these waste paper rates. By employing two regression models and using data for 89 and 81 countries, respectively, the paper concludes that relative waste paper recovery and use are largely market-determined, and depend thus on long-standing economic factors such as population intensity and competitiveness in the world market for paper and board products. We also find evidence that supports the conjecture that rich countries tend to recover relatively more waste paper than is the case in low-income countries, reflecting the higher demand for waste management and environmental policies in more developed economies. As recovery and utilization rates are determined largely by long-standing economic and demographic characteristics the degree of policy flexibility in affecting these rates may be limited. In particular, an ambitious utilization rate target may be very costly to enforce as it can conflict with existing trade patterns of paper and board products as well as with other environmental goals. Additional policy targets may, therefore, be desirable, especially since paper recycling is motivated primarily by environmental concerns and seldom is a benign activity in itself.
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| 5. |
- Carlsson, Patrik, et al.
(författare)
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Delay Performance in IP Routers
- 2004
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Konferensbidrag (refereegranskat)abstract
- The main goals of the paper are towards an understanding of the delay process in best-effort Internet for both non-congested and congested networks. A dedicated measurement system is re-ported for delay measurements in IP routers, which follows specifications of the IETF RFC 2679. The system is using both passive measurements and active probing. Dedicated application-layer software is used to generate UDP traffic with TCP-like characteristics. Pareto traffic models are used to generate self-similar traffic in the link. The reported results are in the form of several impor-tant statistics regarding processing delay of a router, router delay for a single data flow, router delay for more data flows as well as end-to-end delay for a chain of routers. We confirm results reported earlier about the fact that the delay in IP routers is generally influenced by traffic characteristics, link conditions and, at some extent, details in hardware implementation and different IOS releases. The delay in IP routers usually shows heavy-tailed characteristics. It may also occasionally show extreme values, which are due to improper functioning of the routers.
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| 6. |
- Carlsson, Patrik, et al.
(författare)
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Matching Multi-Fractal Process Parameters Against Real Data Traffic
- 2002
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Konferensbidrag (refereegranskat)abstract
- Recent analyses of real data/internet traffic indicate that data traffic exhibits long-range dependence as well as self-similar or multi-fractal properties. By using mathematical models of Internet traffic that share these properties we can perform analytical studies of network traffic. This gives us an opportunity to analyse potential bottlenecks and estimate delays in the networks. Processes with multi-fractal properties can be modeled by multiplying the output of Markov Modulated Rate Processes (MMRP) [1] each defined by four parameters. The MMRP are easily used in stochastic fluid flow modeling. This model is also suited for analysis of other traffic types e.g. VoIP and thus, it allows for integration of different traffic types, i.e. time-sensitive voice traffic with best-effort data traffic. Using this model we can calculate performance parameters for each individual stream that enters the system/model. In this paper we show how to construct a multi-fractal process that is matched to measured data from MMRP sub processes.
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| 7. |
- Carlsson, Patrik, et al.
(författare)
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Modelling of Ethernet Traffic on Multiple Timescales
- 2004
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Konferensbidrag (refereegranskat)abstract
- Ethernet is one of the most common link layer technologies, used in local area networks, wireless networks and wide area networks. There is however a lack of traffic models for Ethernet that is usable in performance analysis. In this paper we use such a model. The model operates on matching multiple moments of the bit rate at several timescales. In order to match the model parameters to measured traffic, five methods have been developed. We use this to model three different links; the BCpOct89 Bellcore trace, an Internet access link and an ADSL link. Our results show that, as the number of sources present on an Ethernet link grows, the model becomes better and less complex.
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| 8. |
- Carlsson, Patrik, et al.
(författare)
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Obtaining Reliable Bit Rate Measurements in SNMP-Managed Networks
- 2002
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Konferensbidrag (refereegranskat)abstract
- The Simple Network Management Protocol, SNMP, is the most widespread standard for Internet management. As SNMP stacks are available on most equipment, this protocol has to be considered when it comes to performance management, traffic engineering and network control. However, especially when using the predominant version 1, SNMPv1, special care has to be taken to avoid erroneous results when calculating bit rates. In this work, we evalute six off-the-shelf network components. We demonstrate that bit rate measurements can be completely misleading if the sample intervals that are used are either too large or too small. We present solutions and work-arounds for these problems. The devices are evaluated with regards to their updating and response behavior.
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| 9. |
- Constantinescu, Doru, et al.
(författare)
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Measurement of One-Way Internet Packet Delay
- 2004
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Konferensbidrag (refereegranskat)abstract
- The paper reports on a dedicated measurement system for delay measurements in IP routers, which follows specifications of the IETF RFC 2679. The system uses both passive and active measurements. Dedicated application-layer software is used to generate traffic. Pareto traffic models are used to generate self-similar traffic in the link. Both packet inter-arrival times and packet sizes are matching real traffic models. A passive measurement system is used for data collection that is based on using several so-called Measurement Points, each of them equipped with DAG monitoring cards. Hashing is used for the identification and matching of packets. The combination of passive measurements and active probing, together with using the DAG monitoring system, gives us an unique possibility to perform precise traffic measurements as well as the flexibility needed to compensate for the lack of analytic solutions.
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| 10. |
- Dinnétz, Patrik, et al.
(författare)
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Population viability analysis of Saxifraga cotyledon, a perennial plant with semelparous rosettes
- 2002
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Ingår i: Plant Ecology. - 1385-0237 .- 1573-5052. ; 159:1, s. 61-71
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Tidskriftsartikel (refereegranskat)abstract
- The aim with this study was to analyse the population dynamics of Saxifraga cotyledon, a rare, long lived herb, with semelparous rosettes. In Sweden, S. cotyledon grows in fragmented habitats at high altitude and is classified as vulnerable according to the IUCN system. From a five year demographical study we estimated population growth rates and extinction risks for one small and one large subpopulation. In the small subpopulation deterministic matrix simulations showed large variation, with two transitions projecting negative and two projecting positive population growth. The large subpopulation also showed large variation, but all yearly transitions projected positive population growth. In both subpopulations survival and growth contributed more than twice as much to population growth rates than did sexual reproduction, vegetative reproduction and the seed bank all taken together. In stochastic simulations the maximum likelihood growth estimator was larger than 1 for both subpopulations. None of the two subpopulations suffer from high extinction rates and although the effect of demographic stochasticity increase extinction risk in small populations it is enough with 70 individuals for a viable population of S. cotyledon. Hence, for the studied population of S. cotyledon, rareness per se is not a good indicator of vulnerability.
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