| 1. |
- Almhöjd, Ulrica S., et al.
(författare)
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Analysis of carious dentine using FTIR and ToF-SIMS.
- 2014
-
Ingår i: Journal of Oral Health and Dental Management. - 1583-5588. ; 13:3, s. 735-744
-
Tidskriftsartikel (refereegranskat)abstract
- Abstract Apart from the Maillard reaction, other processes, such as esterification, take place in carious tissue. The aim of the present study was to analyse sound and carious dentine in terms of ester groups and their reaction with hydrazine derivate using Fourier Transform Infrared Spectroscopy (FTIR) and Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS). Carious and sound dentine from human premolars were excavated in three series (Experimental Parts I-III) and separated into inner and outer layers of carious dentine. The excavated tooth material was analysed with FTIR (Part I). Carious and sound dentine were also exposed to different chemical treatments and analysed with FTIR-Attenuated Total Reflectance (FTIR-ATR; Part II) and ToF-SIMS (Part III). The FTIR absorption spectra showed that the carious tissue contained ester groups, not detected in sound dentine. The results also indicated a higher occurrence of ester groups in the inner dental caries layer than in the outer ones. Potential binding to these ester groups by hydrazine derivative was observed after different chemical treatments with both FTIR-ATR and ToF-SIMS. The results of the present study revealed ester groups unique to the carious dentine which, after reaction with hydrazine derivative, form a covalent bond not found in sound dentine. The staining of carious unique groups would be clinically helpful in detection and prevention unnecessary removal of sound dentine.
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| 2. |
- Ardelius, John, et al.
(författare)
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On the effects of caching in access aggregation networks
- 2012
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Ingår i: ICN 2012, Helsinki, Finland. - : Association for Computing Machinery (ACM). - 9781450314794
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Konferensbidrag (refereegranskat)abstract
- All forecasts of Internet trac point at a substantial growth over the next few years. From a network operator perspective, efficient in-network caching of data is and will be a key component in trying to cope with and profit from this increasing demand. One problem, however, is to evaluate the performance of different caching policies as the number of available data items as well as the distribution networks grows very large.In this work, we develop an analytical model of an aggregation access network receiving a continuous flow of requests from external clients. We provide exact analytical solutions for cache hit rates, data availability and more. This enables us to provide guidelines and rules of thumb for operators and Information-Centric Network designers.Finally, we apply our analytical results to a real VoD trace from a network operator and show that substantial bandwidth savings can be expected when using in-network caching in a realistic setting.
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| 3. |
- Ardelius, John, et al.
(författare)
-
On the effects of caching in access aggregation networks
- 2012. - 6
-
Konferensbidrag (refereegranskat)abstract
- All forecasts of Internet traffic point at a substantial growth over the next few years. From a network operator perspective, efficient in-network caching of data is and will be a key component in trying to cope with and profit from this increasing demand. One problem, however, is to evaluate the performance of different caching policies as the number of available data items as well as the distribution networks grows very large. In this work, we develop an analytical model of an aggregation access network receiving a continuous flow of requests from external clients. We provide exact analytical solutions for cache hit rates, data availability and more. This enables us to provide guidelines and rules of thumb for operators and Information-Centric Network designers. Finally, we apply our analytical results to a real VoD trace from a network operator and show that substantial bandwidth savings can be expected when using in-network caching in a realistic setting.
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| 4. |
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| 5. |
- Arvidsson, Inger, et al.
(författare)
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Discrepancies in pain presentation caused by adverse psychosocial conditions as compared to pain due to high physical workload?
- 2012
-
Ingår i: Work: A Journal of Prevention, Assessment & Rehabilitation. - 1875-9270. ; 41, s. 2472-2475
-
Tidskriftsartikel (refereegranskat)abstract
- Disorders in the musculoskeletal system have been associated with a high physical workload as well as psychosocial and individual factors. It is however not obvious which of these factors that is most important to prevent. Musculoskeletal disorders in neck and upper extremity was assessed by interview and clinical examination in 79 teachers and 93 assisting nurses, all females. Psychosocial work environment was assessed by questionnaire. The physical workload was recorded by technical measurements of postures, movements and muscular load, in 9 teachers and 12 nurses. The physical workload was lower among the teachers, but they had a more demanding psychosocial work environment. Among the nurses, but not in the teachers, the neck-shoulder disorders were associated with a high body mass index (BMI). The teachers reported neck-shoulder complaints to a higher extent than the nurses, but had much lower prevalence of diagnoses in the clinical examination (12% vs. 25%; POR 0.3 CI 0.1 - 1.2; adjusted for age and BMI). The results suggest that adverse psychosocial conditions among the teachers give rise to a different kind of pain in the neck-shoulder region than from physical overload, troublesome but not as severe as the one afflicting the nurses.
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| 6. |
- Arvidsson, Inger, et al.
(författare)
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Rationalization in meat cutting - Consequences on physical workload.
- 2012
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Ingår i: Applied Ergonomics. - : Elsevier BV. - 1872-9126 .- 0003-6870. ; 43:6, s. 1026-1032
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Tidskriftsartikel (refereegranskat)abstract
- Meat cutting is associated with several ergonomic risk factors and a high risk of musculoskeletal disorders. The development of new production systems points to an increased degree of mechanization; instead of subdividing split carcasses of pigs with a knife, the halves are trisected by an electrical saw into 'sixth-parts', resulting in shorter work cycles for the workers. Recently, machine-directed line-production systems have been implemented. This study evaluates differences in the physical workload between the production systems. The postures and movements (inclinometry and goniometry) and muscular load (electromyography) of workers in the split-carcass- (five subjects), sixth-part- (ten) and line-production systems (five) were recorded. Most measures showed a statistically significant trend of declining physical exposure with increasing degrees of mechanization. For example, movement velocities of the upper arm were higher in the split-carcass system (50th percentile: mean 209°/s) than in the sixth-part (103°/s) and line production (81°/s). However, the latter two were not statistically significantly different. A novel method for quantifying posture variation, based on inclinometry, showed that the split-carcass system implied the highest variation of the upper arm postures "within-minute" (i.e., a high range of motion each minute), but the lowest "between-minute" (i.e., a low variation during the course of the workday). In conclusion, the physical workload in the line-production system was significantly lower than in the split-carcass one, and tended also to be lower than in the sixth-part system. However, there may be disadvantages in line production, such as machine-directed work pace and shorter work cycles.
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| 7. |
- Arvidsson, Åke, 1957-, et al.
(författare)
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Analysis of user demand patterns and locality for YouTube traffic
- 2013
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Ingår i: 25th International Teletraffic Congress. - : IEEE Communications Society. - 9781479907991
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Konferensbidrag (refereegranskat)abstract
- Video content, of which YouTube is a major part, constitutes a large share of residential Internet traffic. In this paper, we analyse the user demand patterns for YouTube in two metropolitan access networks with more than 1 million requestsover three consecutive weeks in the first network and more than 600,000 requests over four consecutive weeks in the second network.In particular we examine the existence of “local interest communities”, i.e. the extent to which users living closer to each other tend to request the same content to a higher degree, and it is found that this applies to (i) the two networks themselves; (ii) regions within these networks (iii) households with regions and (iv) terminals within households. We also find that different types of access devices (PCs and handhelds) tend to form similar interest communities.It is also found that repeats are (i) “self-generating” in the sense that the more times a clip has been played, the higher the probability of playing it again, (ii) “long-lasting” in the sense that repeats can occur even after several days and (iii) “semi regular”in the sense that replays have a noticeable tendency tooccur with relatively constant intervals.The implications of these findings are that the benefits from large groups of users in terms of caching gain may be exaggerated, since users are different depending on where they live and what equipment they use, and that high gains can be achieved in relatively small groups or even for individual users thanks totheir relatively predictable behaviour.
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| 8. |
- Arvidsson, Åke, et al.
(författare)
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Analysis of user demand patterns and locality for YouTube traffic
- 2013
-
Ingår i: In the Proceedings of the 25th International Teletraffic Congress (ITC).
-
Konferensbidrag (refereegranskat)abstract
- Video content, of which YouTube is a major part, constitutes a large share of residential Internet traffic. In this paper, we analyse the user demand patterns for YouTube in two metropolitan access networks with more than 1 million requests over three consecutive weeks in the first network and more than 600,000 requests over four consecutive weeks in the second network. In particular we examine the existence of "local interest communities", i.e. the extent to which users living closer to each other tend to request the same content to a higher degree, and it is found that this applies to (i) the two networks themselves; (ii) regions within these networks (iii) households with regions and (iv) terminals within households. We also find that different types of access devices (PCs and handhelds) tend to form similar interest communities. It is also found that repeats are (i) "self-generating" in the sense that the more times a clip has been played, the higher the probability of playing it again, (ii) "long-lasting" in the sense that repeats can occur even after several days and (iii) "semiregular" in the sense that replays have a noticeable tendency to occur with relatively constant intervals. The implications of these findings are that the benefits from large groups of users in terms of caching gain may be exaggerated, since users are different depending on where they live and what equipment they use, and that high gains can be achieved in relatively small groups or even for individual users thanks to their relatively predictable behaviour.
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| 9. |
- Arvidsson, Åke, 1957-, et al.
(författare)
-
Detecting user dissatisfaction and understanding the underlying reasons
- 2013
-
Ingår i: ACM SIGMETRICS / International conference on measurement and modeling of computer systems, SIGMETRICS '13, Pittsburgh, PA, USA, June 17-21, 2013. - : Association for Computing Machinery (ACM). - 9781450319003
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Konferensbidrag (refereegranskat)abstract
- Quantifying quality of experience for network applications is challenging as it is a subjective metric with multiple dimensions such as user expectation, satisfaction, and overall experience. Today, despite various techniques to support differentiated Quality of Service (QoS), the operators still lack of automated methods to translate QoS to QoE, especially for general web applications.In this work, we take the approach of identifying unsatisfactory performance by searching for user initiated early terminations of web transactions from passive monitoring. However, user early abortions can be caused by other factors such as loss of interests. Therefore, naively using them to represent user dissatisfaction will result in large false positives. In this paper, we propose a systematic method for inferring user dissatisfaction from the set of early abortion behaviors observed from identifying the traffic traces. We conduct a comprehensive analysis on the user acceptance of throughput and response time, and compare them with the traditional MOS metric. Then we present the characteristics of early cancelation from dimensions like the types of URLs and objects. We evaluate our approach on four data sets collected in both wireline network and a wireless cellular network.
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| 10. |
- Arvidsson, Åke, 1957-, et al.
(författare)
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Detecting user dissatisfaction from passive monitoring
- 2013
-
Ingår i: Proceedings of Eurocon 2013, International Conference on computer as a tool, Zagreb, Croatia, July 1-4, 2013. - : IEEE Communications Society. - 9781467322300
-
Konferensbidrag (refereegranskat)abstract
- In an increasingly competitive environment it is more important than ever for operators to keep their end users satisfied. User satisfaction is often characterised in terms of Quality of Experience (QoE), a subjective metric with multiple dimensions such as expectations, content, terminal, environment, cost and performance. QoE is typically quantified as MOS, mean opinion score, which is obtained by averaging the ranks of a number of voluntary users for controlled combinations content/terminals/performance etc. While this approach has many advantages, there are also a number of difficulties such as representativeness (the number of users as well as the number of objects and devices all have to be kept small); validity (the results may be biased by the situation, the setting, the renumeration and so on); and applicability (it is not clear how different numbers map to notions such as “acceptable” or “unacceptable” and operators alone cannot do very much about factors such as content).We thus investigate the possibilities of detecting user opinions in the above, simplified, terms and from the network itself; with actual expectations, content, terminals, environments, costs and performance for virtually all users all the time. To this end we revisit the earlier suggestion that user opinions be reflected in their behaviour such that poor performance may result in interrupted requests. These works have, however, considered single flows hence we extend that idea to web pages which are groups of flows. In this paper we present our methods to group flows, interpret users, and characterise performance and we make a first assessment of the correlations between web page interruptions and network performance characteristics.
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| 11. |
- Arvidsson, Åke, et al.
(författare)
-
Tracking user terminals in a mobile communication network
- 2011. - 7
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Patent (populärvet., debatt m.m.)abstract
- There is provided a method of tracking user terminals in a mobile communication network. The method comprising, at a tracking node, determining that a user terminal is located in a tracking area, storing data associated with the tracking area, the data comprising a number of observations of all user terminals at the tracking area at a first time, receiving a page response from the user terminal located in one of the tracking area and a further tracking area, and in the event that the user terminal remains located at the tracking area, updating the data to include the number of page responses received at the tracking area after a first time interval, and in the event that the user terminal is located at the further tracking area, updating the data to include the number of page responses received at the further tracking area after the first time interval.
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| 12. |
- Aurelius, Andreas, et al.
(författare)
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How much of the bandwidth do we actually use? : An investigation of residential access traffic load
- 2012
-
Ingår i: International Conference on Transparent Optical Networks. - : IEEE. - 9781467322270
-
Konferensbidrag (refereegranskat)abstract
- Internet traffic from a fibre based residential access network is investigated concerning traffic volumes and link load. Also the cost of the services is analyzed. We show that 1 Mbps accesses subscribers maintain high loads, and that the price they pay per GB used is five times higher than the one paid by 100 Mbps access subscribers.
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| 13. |
- Aurelius, Andreas, et al.
(författare)
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Leveraging network and traffic measurements for content distribution and interpersonal communication services with sufficient quality
- 2011
-
Konferensbidrag (refereegranskat)abstract
- In this paper, we discuss research problems for enabling content distribution and supporting real-time interpersonal communication services (e.g. voice and video) over best effort networks with sufficient quality. We take a practical view of content distribution and quality, and this is the reason for the term “sufficient”. We argue that the understanding of quality as perceived by the user is a key factor in this context, but also that the understanding of context dependence is a key factor for delivering services which are “good enough” to make the user satisfied. We base our assumptions upon results from the Celtic TRAMMS project, and we describe how to leverage upon the framework for traffic measurements that was built up in that project. Moreover, we identify key technological components that are common for optimization of content delivery and real-time interpersonal communication services such as VoIP and videoconferencing. We also describe how the research problems stated will be tackled in the newly started IPNQSIS project.
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| 14. |
- Hanson, Elizabeth, et al.
(författare)
-
Brukarens roll i välfärdsforskning och utvecklingsarbete
- 2011
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- På 1980-talet blev ”brukare” ett modeord i offentlig förvaltning och förvaltningsforskning. Termen betecknar den som använder sig av välfärdsservice (jfr. engelskans service user), eller ”slutmottagare” av offentlig nyttighet eller åtgärd. Brukare av välfärdstjänster vet hur hjälp och service fungerar i praktiken och kan därför ge synnerligen viktig återkoppling enligt devisen: ”Den som har skorna på fötterna vet var de skaver”. Välfärdsorganisationer har all anledning att involvera brukare i planering och policyarbete i syfte att utveckla förmågan att göra rätt saker. Det finns inte mycket dokumentation och forskning kring brukarmedverkan i utvecklingsarbete och forskning på välfärdsområdet. I synnerhet saknas kunskap om hur välfärdstjänster tas emot och realiseras i brukarens livssammanhang. En ambition i doktorandkursen ”brukarmedverkan i forskning och utvecklingsarbete inom hälso- och sjukvård, socialt arbete och omsorg” var att samla och presentera kunskaper på området. Kursen genomfördes våren 2009 i ett unikt samarbete mellan Karlstads Universitet, Sheffield University i England, Högskolan i Hedmark i Norge, Hälsohögskolan i Jönköping och Högskolan i Borås/FoU Sjuhärad Välfärd. Texterna i denna bok härrör från kursens föreläsningar och paperarbeten. De ger många exempel på hur brukare kan involveras i forskning och utvecklingsarbete, och presenterar en rad praktiska metoder för brukarsamverkan. Boken rekommenderas till välfärdens politiker och yrkespersoner, till studenter som förbereder sig för välfärdens yrken liksom till forskare och utvecklingsarbetare som vill utveckla samarbete med brukare och brukarorganisationer. Den vänder sig givetvis även till brukare och brukarorganisationer som vill engagera sig i forskning och utvecklingsarbete.
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| 15. |
- Hansson, Gert-Åke, et al.
(författare)
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Physical workload in various types of work: Part II. Neck, shoulder and upper arm
- 2010
-
Ingår i: International Journal of Industrial Ergonomics. - : Elsevier BV. - 0169-8141. ; 40:3, s. 267-281
-
Tidskriftsartikel (refereegranskat)abstract
- To explore the correlation between, and the variation in, various measures of exposure to potential risk factors for work-related upper extremity musculoskeletal disorders (UE-WMSDs), physical workload was measured in 43 types of work (713 individuals), using inclinometry for the head and upper arms, and electromyography (EMG) for the trapezius muscles. Many exposure measures were highly correlated. Head flexion (90th percentile), extension (1st percentile), and movements (50th percentile); arm elevation (99th percentile) and movements (50th percentile); trapezius muscular rest (fraction of time) and peak load (90th percentile), constitute main exposure dimensions. The variations were large: head: flexion 9 degrees-63 degrees, extension -39 degrees-4 degrees, movements 2.3-33 degrees/s; arm: elevation 49 degrees-124 degrees, movements 3.0-103 degrees/s; trapezius: muscular rest 0.8%-52% of time, peak load 3.1%-24% of maximal EMC. Even within work categories, e.g. "repetitive industrial", there were large variations. Somewhat higher loads were recorded on the right as compared to the left side (differences: arm elevation 2, arm movements 19%; trapezius peak load 18%), but these were small compared to the differences due to work. There were high correlations between movements of arm and head (r(s) = 0.96), as well as arm and wrist (r(s) = 0.92), and between, on the one hand, trapezius muscular rest and peak load, and on the other, arm and head movements (vertical bar r(s)vertical bar = 0.47-0.62), as well as arm elevation (vertical bar r(s)vertical bar = 0.54-0.85), which has to be considered when assessing exposure-response relations. Relevance to industry: Direct measurements provide objective and quantitative data of the main physical risk factors for UE-WMSDs, appropriate for estimating the risk, as well as giving priority to and evaluating interventions. (C) 2009 Elsevier B.V. All rights reserved.
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| 16. |
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| 17. |
- Johannesson, Pär, 1969, et al.
(författare)
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A Robustness Approach to Reliability
- 2013
-
Ingår i: Quality and Reliability Engineering International. - : Wiley. - 1099-1638 .- 0748-8017. ; 29:1, s. 17-32
-
Forskningsöversikt (refereegranskat)abstract
- Reliability of products is here regarded with respect to failure avoidance rather than probability of failure. To avoid failures,we emphasize variation and suggest some powerful tools for handling failures due to variation. Thus, instead of technicalcalculation of probabilities from data that usually are too weak for correct results, we emphasize the statistical thinking thatputs the designers focus on the critical product functions.Making the design insensitive to unavoidable variation is called robust design and is handled by (i) identification andclassification of variation, (ii) design of experiments to find robust solutions, and (iii) statistically based estimations of propersafety margins.Extensions of the classical failure mode and effect analysis (FMEA) are presented. The first extension consists of identifyingfailure modes caused by variation in the traditional bottom–up FMEA analysis. The second variation mode and effect analysis(VMEA) is a top–down analysis, taking the product characteristics as a starting point and analyzing how sensitive thesecharacteristics are to variation.In cases when there is sufficient detailed information of potential failure causes, the VMEA can be applied in its mostadvanced mode, the probabilistic VMEA. Variation is then measured as statistical standard deviations, and sensitivities aremeasured as partial derivatives. This method gives the opportunity to dimension tolerances and safety margins to avoidfailures caused by both unavoidable variation and lack of knowledge regarding failure processes.
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| 18. |
- Kihl, Maria, et al.
(författare)
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Analysis of facebook content demand patterns
- 2014
-
Ingår i: 2014 International Conference on Smart Communications in Network Technologies, SaCoNeT 2014. - 9781479951963
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Konferensbidrag (refereegranskat)abstract
- Data volumes in communication networks increase rapidly. Further, usage of social network applications is very wide spread among users, and among these applications, Facebook is the most popular. In this paper, we analyse user demands patterns and content popularity of Facebook generated traffic. The data comes from residential users in two metropolitan access networks in Sweden, and we analyse more than 17 million images downloaded by almost 16,000 Facebook users. We show that the distributions of image popularity and user activity may be described by Zipf distributions which is favourable for many types of caching. We also show that Facebook activity is more evenly spread over the day, compared to more defined peak hours of general Internet usage. Looking at content life time, we show that profile pictures have a relatively constant popularity while for other images there is an initial, short peak of demand, followed by a longer period of significantly lower and quite stable demand. These findings are useful for designing network and QoE optimisation solutions, such as predictive pre-fetching, proxy caching and delay tolerant networking.
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| 19. |
- Kreuger, Per, et al.
(författare)
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zCap : a zero configuration adaptive paging and mobility management mechanism
- 2013. - 7
-
Ingår i: International Journal of Network Management. - : Wiley. - 1055-7148 .- 1099-1190. ; 23:4, s. 235-258
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Tidskriftsartikel (refereegranskat)abstract
- Today, cellular networks rely on fixed collections of cells (tracking areas) for user equipment localisation. Locating users within these areas involves broadcast search (paging), which consumes radio bandwidth but reduces the user equipment signalling required for mobility management. Tracking areas are today manually configured, hard to adapt to local mobility and influence the load on several key resources in the network. We propose a decentralised and self-adaptive approach to mobility management based on a probabilistic model of local mobility. By estimating the parameters of this model from observations of user mobility collected online, we obtain a dynamic model from which we construct local neighbourhoods of cells where we are most likely to locate user equipment. We propose to replace the static tracking areas of current systems with neighbourhoods local to each cell. The model is also used to derive a multi-phase paging scheme, where the division of neighbourhood cells into consecutive phases balances response times and paging cost. The complete mechanism requires no manual tracking area configuration and performs localisation efficiently in terms of signalling and response times. Detailed simulations show that significant potential gains in localisation effi- ciency are possible while eliminating manual configuration of mobility management parameters. Variants of the proposal can be implemented within current (LTE) standards.
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| 20. |
- Kreuger, Per, et al.
(författare)
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Zero configuration adaptive paging (zCap)
- 2012
-
Ingår i: VTC Fall 2012. - : IEEE Communications Society. - 9781467318792
-
Konferensbidrag (refereegranskat)abstract
- Today, cellular networks rely on fixed collections of cells (tracking areas) for handset localisation. This management parameter is manually configured and maintained and is not regularly adapted to changes in use patterns. We present a decentralised approach to localisation, based on a self-adaptive probabilistic mobility model. Estimates of model parameters are built from observations of mobility patterns collected online using a distributed algorithm. Based on these estimates, dynamic local neighbourhoods of cells are formed and maintained by the mobility management entities of the network. These neighbourhoods replace the static tracking areas used in current implementations by using the tracking area list facility of LTE. The model is also used to derive a multi phase paging scheme, where the division of cells into consecutive phases is optimal with respect to a set balance between response times and paging cost. The approach requires no manual tracking area configuration, and performs localisation efficiently in terms of number of location updates, page
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| 21. |
- Kreuger, Per, et al.
(författare)
-
Zero configuration adaptive paging (zCap)
- 2012. - 14
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Ingår i: IEEE Vehicular Technology Conference. - : IEEE. - 9781467318815
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Konferensbidrag (refereegranskat)abstract
- Today, cellular networks rely on fixed collections of cells (tracking areas) for handset localisation. This management parameter is manually configured and maintained and is not regularly adapted to changes in use patterns. We present a decentralised approach to localisation, based on a self-adaptive probabilistic mobility model. Estimates of model parameters are built from observations of mobility patterns collected on- line using a distributed algorithm. Based on these estimates, dynamic local neighbourhoods of cells are formed and maintained by the mobility management entities of the network. These neighbourhoods replace the static tracking areas used in current implementations by using the tracking area list facility of LTE. The model is also used to derive a multi phase paging scheme, where the division of cells into consecutive phases is optimal with respect to a set balance between response times and paging cost. The approach requires no manual tracking area configuration, and performs localisation efficiently in terms of number of location updates, page messages per localisation request and response times.
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| 22. |
- Laulajainen, Jukka Pekka, et al.
(författare)
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Study of YouTube demand patterns in mixed public and campus WiFi network
- 2014
-
Ingår i: IWCMC 2014 - 10th International Wireless Communications and Mobile Computing Conference. - 9781479909599 ; , s. 635-641
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Konferensbidrag (refereegranskat)abstract
- In this paper we study traffic patterns in a large municipal WiFi network and in particular those of the most bandwidth hungry application, viz. YouTube, for which we provide a detailed analysis of demand in different geographical areas and over time. We consider the possibilities to reduce network traffic and increase Quality of Experience (QoE) by serving repeated requests for YouTube videos from caches placed either at the network head end, at the wireless access points, or in the user devices. Our data confirms that a significant part of the YouTube traffic can be served by such devices and that there exists a potential to optimize caching performance by exploiting the content demand locality. We also discover a previously unknown pattern of periodicity in content demand and present a simple example of how to exploit this in cache design
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| 23. |
- Li, Jie, et al.
(författare)
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A five year perspective of traffic pattern evolution in a residential broadband access network
- 2012
-
Ingår i: Future Network & MobileSummit 2012. - 9781905824304
-
Konferensbidrag (refereegranskat)abstract
- In this paper we describe a systematic study on long-term evolution of residential broadband Internet traffic covering 5 calendar years from June 2007 to May 2011. The traffic evolution is characterized both in the term of the total traffic volume, as well as the traffic volumes and shares for different application categories (file sharing, video streaming etc.), with the focus on comparing the traffic on the per IP user basis and among different broadband subscription groups. The results show that the average daily total traffic generated by each private end user increased only by about 33 % during the past 5 years. Further, the results show that the P2P filesharing has been dominating the network total traffic, but the daily file-sharing traffic volume per end user largely remains the same. Also, the daily streaming-media traffic volume per end user has increased dramatically by over 500% during the studied period of time. In the meantime, the daily web-browsing traffic volume per end user has increased by about 300%. Finally, a further investigation among 4 different FTTH broadband subscription groups with 1, 10 , 30, and 100 Mbit/s symmetric access speeds shows that the lower the access speed, the more diversified the end user traffic tend to be.
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| 24. |
- Li, Jie, et al.
(författare)
-
A five year perspective of traffic pattern evolution in a residential broadband access network
- 2012
-
Ingår i: 2012 Future Network and Mobile Summit, FutureNetw 2012. - 9781905824304
-
Konferensbidrag (refereegranskat)abstract
- In this paper we describe a systematic study on long-term evolution of residential broadband Internet traffic covering 5 calendar years from June 2007 to May 2011. The traffic evolution is characterized both in the term of the total traffic volume, as well as the traffic volumes and shares for different application categories (file sharing, video streaming etc.), with the focus on comparing the traffic on the per IP user basis and among different broadband subscription groups. The results show that the average daily total traffic generated by each private end user increased only by about 33 % during the past 5 years. Further, the results show that the P2P file-sharing has been dominating the network total traffic, but the daily file-sharing traffic volume per end user largely remains the same. Also, the daily streaming-media traffic volume per end user has increased dramatically by over 500% during the studied period of time. In the meantime, the daily web-browsing traffic volume per end user has increased by about 300%. Finally, a further investigation among 4 different FTTH broadband subscription groups with 1, 10, 30, and 100 Mbit/s symmetric access speeds shows that the lower the access speed, the more diversified the end user traffic tend to be.
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| 25. |
- Li, Jie, et al.
(författare)
-
Performance analysis of local caching replacement policies for internet video streaming services
- 2014
-
Ingår i: SoftCOM 2014. - : IEEE Communications Society. - 9789532900521
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Konferensbidrag (refereegranskat)abstract
- In this work, the performance of 5 representative caching replacement policies was investigated and compared for caching Internet video-on-demand (VoD) in local access networks. Two measured traces of end-user requests were used in the analyses for two typical VoD services: TV-on-demand and user generated content represented by YouTube. The studied policies range from simple least recently used (LRU) and least frequently used (LFU) algorithms to more advanced ones denoted as LFU-dynamic lifespan (LFU-DL), Adaptive replacement cache (ARC) and Greedy-dual size frequency (GDSF). Our results show that the ARC policy always outperforms the other policies due to its adaptive nature and its ability to track changes in the traffic patterns. On the other hand, the simple LRU policy can also achieve a caching performance which is comparable to that of the more advanced ARC policy especially for the TV-on-demand service when the potential caching gain is high. On the contrary, the simple LFU policy always shows the poorest performance.However, by applying a proper lifespan supplement under the LFU-DL policy, the caching performance can be effectively enhanced to the level achievable using ARC and LRU policies. Moreover, the GDSF policy does not outperform simple LRU or LFU-DL, especially for YouTube video clips when the potential caching gain is relatively low. The advantage of GDSF manifested in our analysis is, however, its outstanding cache space usage efficiency among the five studied caching algorithms.
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| 26. |
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| 27. |
- Li, Jie, et al.
(författare)
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YouTube traffic content analysis in the perspective of clip category and duration
- 2013
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Ingår i: 2013 Fourth International Conference on the Network of the Future (NOF 2013). - : IEEE Communications Society. - 9781479916429
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Konferensbidrag (refereegranskat)abstract
- In this work, we study YouTube traffic characteristics in a medium-sized Swedish residential municipal network that has ~ 2600 mainly FTTH broadband-connected households. YouTube traffic analyses were carried out in the perspective of video clip category and duration, in order to understand their impact on the potential local network caching gains. To the best of our knowledge, this is the first time systematic analysis of YouTube traffic content in the perspective of video clip category and duration in a residential broadband network. Our results show that the requested YouTube videoclips from the end users in the studied network were imbalanced in regarding the video categories and durations. The dominating video category was Music, both in terms of the total traffic share as well as the contribution to the overall potential local network caching gain. In addition, most of the requested video clips were between 2-5 min in duration, despite video clips with durations over 15 min were also popular among certain video categories, e.g. film videos.
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| 28. |
- Li, Jie, et al.
(författare)
-
Youtube traffic content analysis in the perspective of clip category and duration
- 2013
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Ingår i: [Host publication title missing].
-
Konferensbidrag (refereegranskat)abstract
- In this work, we study YouTube traffic characteristics in a medium-sized Swedish residential municipal network that has - 2600 mainly FTTH broadband-connected households. YouTube traffic analyses were carried out in the perspective of video clip category and duration, in order to understand their impact on the potential local network caching gains. To the best of our knowledge, this is the first time systematic analysis of YouTube traffic content in the perspective of video clip category and duration in a residential broadband network. Our results show that the requested YouTube video clips from the end users in the studied network were imbalanced in regarding the video categories and durations. The dominating video category was Music, both in terms of the total traffic share as well as the contribution to the overall potential local network caching gain. In addition, most of the requested video clips were between 2-5 min in duration, despite video clips with durations over 15 min were also popular among certain video categories, e.g. film videos.
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| 29. |
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| 30. |
- Nordander, Catarina, et al.
(författare)
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Exposure-response relationships in work-related musculoskeletal disorders in elbows and hands - A synthesis of group-level data on exposure and response obtained using uniform methods of data collection.
- 2013
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Ingår i: Applied Ergonomics. - : Elsevier BV. - 1872-9126 .- 0003-6870. ; 44:2, s. 214-253
-
Tidskriftsartikel (refereegranskat)abstract
- There is a serious lack of quantitative data regarding exposure-response relationships between occupational risk factors and musculoskeletal elbow and hand disorders. This paper explores such relationships in group-level data from our earlier cross-sectional studies. Prevalence of complaints (Nordic Questionnaire) and diagnoses (physical examination) were recorded in 19 groups of female workers (1891 individuals), and 8 groups of male workers (761 individuals), with highly similar work tasks within each group. Linear regression was performed on the group means of wrist postures and angular velocity (obtained by electrogoniometers), as well as muscular load (obtained using electromyography), recorded in representative sub-samples, and psychosocial exposure (Job Content Questionnaire). To tackle within-group variations in physical exposure, sensitivity analyses were performed by bootstrapping simulations, rendering confidence intervals. The sex-adjusted slope of the regression line (β) for wrist angular velocity vs. complaints during the past 7 days was 0.6%/(°/s), (95% CI 0.3-0.9), and for carpal tunnel syndrome (CTS) 0.2%/(°/s), (0.1-0.3). For palmar flexion, p50, β over the past 7 days was 0.8%/° (0.4-1.2); for CTS 0.3%/° (0.1-0.5); β for muscular activity p90: 0.9%/%MVE (0.3-1.6), and 0.3%/%MVE (-0.03-0.6) respectively and finally β for muscular rest: -1.2%/%time (-2.4-0.03) and -0.5%/%time (-0.9 to -0.01). Relationships were also demonstrated for low job control, job strain and isostrain. Women exhibited a higher prevalence of complaints than men. In conclusion, we have established quantitative exposure-response relationships between physical work load and elbow/hand disorders. Wrist angular velocity was the most consistent risk factor.
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| 31. |
- Nordell, Viktor, et al.
(författare)
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Concurrency and locality of content demand
- 2013
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Ingår i: 2013 International Conference on Smart Communications in Network Technologies (SaCoNeT 2013). - 9781479906956
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Konferensbidrag (refereegranskat)abstract
- Distribution of media data over the Internet is increasing in popularity and volume. This poses challenges not only for network operators but also for service providers when it comes to serving the demand in a cost-efficient way. In this paper, we approach this problem by investigating the potential of co-operative approaches where locality in space (users in the same network) and locality in time (concurrent downloads) are exploited such that as many requests as possible may behandled inside the access and metro networks. This approach may contribute not only to reducing transport costs (less traffic in core networks and at peering points) by but also improve the end user experience (by reduced round trip times and exclusion of some possible bottlenecks). To this end we develop a method to measure the possible gains from, firstly, optimal handling of concurrent downloads and, secondly, optimal utilization localavailability. We apply the method to BitTorrent data from two metropolitan access networks and find that the bandwidth savings amount to between 10% and 20% when optimizing concurrent downloads and between 56% and 66% when exploiting local availability with a simulated network cache.
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| 32. |
- Nordell, Viktor, et al.
(författare)
-
Concurrency and locality of content demand
- 2013
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Ingår i: 2013 International Conference on Smart Communications in Network Technologies, SaCoNeT 2013. - 9781479906949
-
Konferensbidrag (refereegranskat)abstract
- Distribution of media data over the Internet is increasing in popularity and volume. This poses challenges not only for network operators but also for service providers when it comes to serving the demand in a cost-efficient way. In this paper, we approach this problem by investigating the potential of co-operative approaches where locality in space (users in the same network) and locality in time (concurrent downloads) are exploited such that as many requests as possible may be handled inside the access and metro networks. This approach may contribute not only to reducing transport costs (less traffic in core networks and at peering points) by but also improve the end user experience (by reduced round trip times and exclusion of some possible bottlenecks). To this end we develop a method to measure the possible gains from, firstly, optimal handling of concurrent downloads and, secondly, optimal utilization local availability. We apply the method to BitTorrent data from two metropolitan access networks and find that the bandwidth savings amount to between 10% and 20% when optimizing concurrent downloads and between 56% and 66% when exploiting local availability with a simulated network cache.
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| 33. |
- Scheringer, Martin, et al.
(författare)
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Planetary boundaries for chemical pollution
- 2012
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Ingår i: Dioxin 2012 - 32nd International Symposium on Halogenated Persistent Organic Compounds.
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Konferensbidrag (refereegranskat)abstract
- Based on the concept by Rockström et al the paper discusses the principles of the concept in relation to chemical pollution and the specific challenges associated to that. The paper conclude the chemical pollution is certainly a strong anthropogenic impact of global relevance. However, because of the local or regional nature of many exposures and effects caused by chemicals, there is probably not a single tipping point for the global system that would have to be reflected by a planetary boundary. Therefore, in order to assess and manage chemical pollution, it seems to be more promising to focus on certain classes of chemicals separately and to derive boundaries of different types for these classes of chemicals, as illustrated in the paper for CFCs, POPs and food contaminants.
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| 34. |
- Zhang, Ying, et al.
(författare)
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Understanding HTTP flow rates in cellular networks
- 2014
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Ingår i: Networking 2014. - : IFIP. - 9783901882586
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Konferensbidrag (refereegranskat)abstract
- Data traffic in cellular networks increased tremendously over the past few years and this growth is predicted to continue over the next few years. Due to differences in access technology and user behavior, the characteristics of cellular traffic can differ from existing results for wireline traffic. In this study we focus on understanding the flow rates and on the relationship between the rates and other flow properties by analyzing packet level traces collected in a large cellular network. To understand the limiting factors of the flow rates, we further analyze the underlying causes behind the observed rates, e.g.,network congestion, access link or end host configuration. Our study extends other related work by conducting the analysis from a unique dimension, the comparison with traffic in wired networks, to reveal the unique properties of cellular traffic. We find that they differ in variability and in the dominant rate limiting factors.
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| 35. |
- Zhang, Ying, et al.
(författare)
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Understanding the characteristics of cellular data traffic
- 2012
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Ingår i: CellNet 2012. - : Association for Computing Machinery (ACM). - 9781450314756
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Konferensbidrag (refereegranskat)abstract
- Because of rapidly growing subscriber populations, advances in cellular communication technology, increasingly capable user terminals, and the expanding range of mobile applications, cellular networks have experienced a significant increase in data traffic, the dominant part of which is carried by the http protocol. Understanding the characteristics of this traffic is important for network design, traffic modeling, resource planning and network control. In this study we present a comprehensive characterization study of mobile http-based traffic using packet level traces collected in a large cellular network. We analyze the traffic using metrics at packet level, flow level and session level. For each metric, we conduct a comparison between traffic from different applications, as well as comparison to traffic in a wired network. Finally, we discuss the implications of our findings for better resource utilization in cellular infrastructures.
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