| 1. |
- Yrjänäinen, Väinö, et al.
(författare)
-
The Swedish Parliament Corpus 1867-2022
- 2024
-
Ingår i: 2024 Joint International Conference on Computational Linguistics, Language Resources and Evaluation, LREC-COLING 2024 - Main Conference Proceedings. - : ELRA Language Resource Association. - 9782493814104 ; , s. 16100-16112
-
Konferensbidrag (refereegranskat)abstract
- The Swedish parliamentary records are an important source material for social science and humanities researchers. We introduce a new research corpus, the Swedish Parliament Corpus, which is larger and more developed than previously available research corpora for the Swedish parliament. The corpus contains annotated and structured parliamentary records over more than 150 years, through the bicameral parliament (1867-1970) and the unicameral parliament (1971-). In addition to the records, which contain all speeches in the parliament, we also provide a database of all members of parliament over the same period. Along with the corpus, we describe procedures to ensure data quality. The corpus facilitates detailed analysis of parliamentary speeches in several research fields.
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| 2. |
- Bengmark, Samuel, 1965, et al.
(författare)
-
PREP- Pragmatic Research on Educational Practice
- 2023
-
Ingår i: SEFI 2023 - 51st Annual Conference of the European Society for Engineering Education : Engineering Education for Sustainability, Proceedings - Engineering Education for Sustainability, Proceedings. - : SEFI. - 9782873520267 ; , s. 163-172
-
Konferensbidrag (refereegranskat)abstract
- We investigate a concept called PREP - Pragmatic Research on Educational Practice, with the goal of engaging engineering educators in studying, documenting and sharing their initiatives to improve teaching practices. This concept is compared to other methodologies where the researcher and educational practitioner sometimes coincide. The study is based on a pilot, with six participants following the PREP program for three months, which we study autoethnographically. We also carried out a focus group discussion (n=12) to investigate to what extent university teachers regard the ideas from the PREP program as helpful for studying educational activities and sharing what they do and find.
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| 3. |
- Carbonaro, M., et al.
(författare)
-
Combining high-density electromyography and ultrafast ultrasound to assess individual motor unit properties in vivo
- 2023
-
Ingår i: Convegno nazionale di bioingegneria: eight national congress of bioengineering. - : Patron Editore S.r.l.. - 2724-2129. - 9788855580113 ; , s. 1-4
-
Konferensbidrag (refereegranskat)abstract
- This study aims to compare two methods for the identification of anatomical and mechanical motor unit (MU) properties through the integration of high-density surface electromyography (HDsEMG) and ultrafast ultrasound (UUS). The two approaches rely on a combined analysis of the firing pattern of active MUs, identified from HDsEMG, and tissue velocity sequences of the muscle cross-section, obtained from UUS. The first method is the spike-triggered averaging (STA) of the tissue velocity sequence based on the occurrences of MU firings. The second is a method based on spatio-temporal independent component analysis (STICA) enhanced with the information of single MU firings. We compared the capability of these two approaches to identify the regions where single MU fibers are located within the muscle cross-section (MU displacement area) in vivo. HDsEMG signals and UUS images were detected simultaneously from biceps brachii in ten participants (6 males and 4 females) during low-level isometric elbow flexions. Experimental signals were processed by implementing both STA and STICA approaches. The medio-lateral distance between the estimated MU displacement areas and the centroid of the MU action potential distributions was used to compare the two methods. We found that STICA and STA are able to detect MU displacement areas. However, STICA provides more precise estimations to the detriment of higher computational complexity.
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| 4. |
- Karjalainen, Suvi, et al.
(författare)
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Teachers' voice use and wellbeing in relation to the classroom acoustics and background noise
- 2023
-
Ingår i: Proceedings of the 10<sup>th</sup> Convention of theEuropean Acoustics Association Forum Acusticum 2023. - : European Acoustics Association, EAA. - 9788888942674
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Konferensbidrag (refereegranskat)abstract
- Although many studies have shown that teachers' vocal health is challenged by noise and the room acoustics, research on classroom sound environment from the perspective of teachers' well-being is scarce. This study aimed to explore the relationship between teachers' wellbeing, voice use and classroom acoustics. In this study, wellbeing refers to self-reported vocal health, self-assessed level of stress, burnout and self-efficacy. Twenty-three primary-school teachers answered questionnaires on well-being. In each teacher's classroom, the acoustical properties were measured with the variables reverberation time, clarity of speech (C50) and ventilation system noise (VSN). A series of non-parametric correlations were run to determine the relationship between teachers' well-being and classroom acoustics. There was a significant bivariate correlation between burnout and VSN, (dBA), that, however, after correction for multiple analyses remained non significant, Voice symptoms correlated with VSN and teaching grade. This study indicates that higher degree of burnout in teachers is associated with higher levels of VSN in classrooms. Moreover, teachers' voice symptoms increase with higher levels of VSN. Teachers teaching lower grades had more voice symptoms than those teaching higher grades.
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| 5. |
- Koukouvinou, Panagiota, et al.
(författare)
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Ghost in the machine : theorizing data knowledge in the age of intelligent technologies
- 2023
-
Ingår i: Rising like a phoenix. - : AIS eLibrary. - 9781713893622 ; , s. 1-9
-
Konferensbidrag (refereegranskat)abstract
- AI technologies have led to new ways of thinking about data, knowledge, and organizations. Despite the arguments that data speak for themselves, the era of datafication demands revisiting data and knowledge and reflecting on new ways of theorizing. Considering that working with data is important for most employees, there is a need to investigate how the knowing of data can be achieved. In this paper, we move beyond the factual view of data and the hierarchical view of data and knowledge, to introduce data knowledge as a new type of knowledge. We present a first step towards a theory of explanation of what is data knowledge in today ́s organizations. To investigate this, we apply an etymological lens, and review systematically the IS literature. Our preliminary findings demonstrate unveiling data, balancing between intuition and data, acknowledging external and internal capabilities, and realizing data, as the four main concepts of data knowledge.
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| 6. |
- Tärneberg, William, et al.
(författare)
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The 6G Computing Continuum (6GCC) : Meeting the 6G computing challenges
- 2022
-
Ingår i: 2022 1st International Conference on 6G Networking, 6GNet 2022. - : IEEE Computer Society. - 9781665467636
-
Konferensbidrag (refereegranskat)abstract
- 6G systems, such as Large Intelligent Surfaces, will require distributed, complex, and coordinated decisions through-out a very heterogeneous and cell free infrastructure. This will require a fundamentally redesigned software infrastructure accompanied by massively distributed and heterogeneous computing resources, vastly different from current wireless networks. To address these challenges, in this paper, we propose and motivate the concept of a 6G Computing Continuum (6GCC) and two research testbeds, to advance the rate and quality of research. 6G Computing Continuum is an end-to-end compute and software platform for realizing large intelligent surfaces and its tenant users and applications. One for addressing the challenges or orchestrating shared computational resources in the wireless domain, implemented on a Large Intelligent Surfaces testbed. Another simulation-based testbed is intended to address scalability and global-scale orchestration challenges.
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| 7. |
- Larsson, Lars, 1983-, et al.
(författare)
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Adaptive and Application-agnostic Caching in Service Meshes for Resilient Cloud Applications
- 2021
-
Ingår i: Proceedings of the 2021 IEEE Conference on Network Softwarization (NetSoft) : Accelerating Network Softwarization in the Cognitive Age - Accelerating Network Softwarization in the Cognitive Age. - : IEEE. - 9781665405225 ; , s. 176-180
-
Konferensbidrag (refereegranskat)abstract
- Service meshes factor out code dealing with inter-micro-service communication. The overall resilience of a cloud application is improved if constituent micro-services return stale data, instead of no data at all. This paper proposes and implements application agnostic caching for micro services. While caching is widely employed for serving web service traffic, its usage in inter-micro-service communication is lacking. Micro-services responses are highly dynamic, which requires carefully choosing adaptive time-to-life caching algorithms. Our approach is application agnostic, is cloud native, and supports gRPC. We evaluate our approach and implementation using the micro-service benchmark by Google Cloud called Hipster Shop. Our approach results in caching of about 80% of requests. Results show the feasibility and efficiency of our approach, which encourages implementing caching in service meshes. Additionally, we make the code, experiments, and data publicly available.
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| 8. |
- Dolešová, Markéta, et al.
(författare)
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Designing with More-than-Human Food Practices for Climate-Resilience
- 2020
-
Ingår i: DIS 2020 Companion. - New York, NY, USA : Association for Computing Machinery (ACM). - 9781450379878 ; , s. 381-384
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Konferensbidrag (refereegranskat)abstract
- Climate change is an increasingly urgent, complex problem, with consequences threatening human and non-human lives across the globe. Legislative and citizen-driven responses are valuable but insufficient, and their practical feasibility is unclear. Emerging design research suggests embracing imaginative, creative approaches to support engagement with climate-change issues and inspire collective reflection. This workshop investigates how such approaches can be applied through co-creative design experimentation in the context of human-food practices, which are now recognized as a key driver of climate change. We will reflect on existing climate-change mitigation proposals by imagining their plausible implementations as climate-resilient food practices, emphasizing more-than-human concerns. The workshop is organized as part of a two-day program titled Experimental Food Design for Sustainable Futures inviting diverse participants interested in contributing toward sustainable socio-ecological transformations.
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| 9. |
- Larsson, Lars, 1983-, et al.
(författare)
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Quality-Elasticity: Improved Resource Utilization, Throughput, and Response Times Via Adjusting Output Quality to Current Operating Conditions
- 2019
-
Ingår i: IEEE International Conference on Autonomic Computing (ICAC). - : IEEE. - 9781728124124 - 9781728124117
-
Konferensbidrag (refereegranskat)abstract
- This work addresses two related problems for on-line services, namely poor resource utilization during regular operating conditions, and low throughput, long response times, or poor performance under periods of high system load. To address these problems, we introduce our notion of quality-elasticity as a manner of dynamically adapting response qualities from software services along a fine-grained spectrum. When resources are abundant, response quality can be increased, and when resources are scarce, responses are delivered at a lower quality to prioritize throughput and response times. We present an example of how a complex online shopping site can be made quality-elastic. Experiments show that, compared to state of the art, improvements in throughput (57% more served queries), lowered response times (8 time reduction for 95th percentile responses), and an estimated 40% profitability increase can be made using our quality-elastic approach. When resources are abundant, our approach may achieve upwards of twice as high resource utilization as prior work in this field.
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| 10. |
- Mitra, Amit, et al.
(författare)
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Liminality in narratives of integration: Influence of social media use on situational ethnicity of migrants
- 2018
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Given difficult conditions in different regions of the world, it is no wonder that people embark on journeys to regions where they may feel secure, seek refuge, be able to acquire a livelihood, as well as carry on a type of living. At the same time, when migrants arrive in a new country that they have hitherto never been to, there is an expectation that they will integrate into the host country’s way of life, buy into shared beliefs and prevalent value systems. Many migrants are active social media users and so their digital proclivities tend to define their narratives as does their physical realities. Therefore, deconstruction of digital narratives of migrants may lead to a conceptualisation of transitional ethnicities pertaining to virtual and physical journeys. Preliminary evidence on social media use among migrants to Germany, do not attest to the unalloyed blessing that social media is in aiding integration. In contrast social media-based engagement by migrants highlights encouragement of effects of isolation, and consequent ghetto-isation. Drawing upon extant literature on anthropology of migration, we argue that migrants’ use of social media creates a liminality that is synonymous to ambiguity and disorientation that may diminish through a composite adaptation of virtual and physical ethnic identities. Evidence for the study was collected through in-depth interviews of migrants in several Swedish cities including Stockholm, Jönköping, Malmö, and Gothenburg.
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| 11. |
- Nylander, Tommi, et al.
(författare)
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Brownout(CC) : Cascaded Control for Bounding the Response Times of Cloud Applications
- 2018
-
Ingår i: 2018 ANNUAL AMERICAN CONTROL CONFERENCE (ACC). - : IEEE. - 9781538654286 ; , s. 3354-3361
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Konferensbidrag (refereegranskat)abstract
- Cloud computing has emerged as an inexpensive and powerful computing paradigm, to the point that now even applications with hard deadlines are executed in the cloud. It may happen, due to unexpected events, that an application becomes popular and receives a lot of attention and client requests in a short period of time. Provisioning computing capacity for such applications is quite a difficult task, because content popularity cannot he easily predicted. One of the main problems in case content has to be served with a hard deadline is to ensure that this deadline is respected, even in the presence of popularity spikes. To this end, partial computation and graceful degradation were exploited, originating the brownout framework. Applications would degrade the user experience in the presence of load variations, to guarantee that deadlines are met. Two different control paradigms were applied to brownout: discrete-time control of optional content percentage over a period and event-based queue management. The first one had reasonable performance providing formal guarantees about the solution. The second one was able to improve the performance and keep the response time at the setpoint better, but suffered from the drawback of not providing formally grounded mathematical guarantees. In this work we combine the best of both worlds, providing a cascaded controller for brownout, based on a more precise model of the cloud application with respect to the original design. The Brownout(CC) controller achieves performance comparable with the event based version, without sacrificing formal guarantees.
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| 12. |
- Ramirez-Pasillas, Marcela, et al.
(författare)
-
Family resilience in immigrants' entrepreneurial opportunity creation process
- 2018
-
Konferensbidrag (refereegranskat)abstract
- This paper adopts an inductive case study to examine the role of family resilience in the immigrants’ opportunity creation process. We employ family resilience (Walsh, 2002) and the opportunity creation process (Alvarez and Barney, 2007). We conducted an inductive case study on four cases of immigrant entrepreneurs who established businesses in Sweden and who have their origins in Lebanon and Syria, Cameroon, and Mexico. We found three family resilience capabilities occurring to withstand and rebound from adversity which facilitate the opportunity creation process. First, family flexibility facilitates the generation of the entrepreneurial idea, which implies that when immigrant entrepreneurs adjust to new roles in the host country and new situations in the home country, the development of new entrepreneurial idea is triggered when new situations in the home country occurs which make immigrant entrepreneurs adjust to new roles in their families. Second, family as collaborative problem solving to shape an entrepreneurial idea, which centers on the collective support from the family that the immigrant entrepreneurs can rely on to develop the idea further. Third, family as social and economic resourcing for refining an entrepreneurial idea which involves leveraging different resources through kin’s support to modify entrepreneurial idea.
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| 13. |
- Hesameddin, Fatehi, et al.
(författare)
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Effect of Volatile Reactions on the Thermochemical Conversion of Biomass Particles
- 2017
-
Ingår i: 8th International Conference on Applied Energy (ICAE2016). - : Elsevier. ; 105, s. 4648-4654
-
Konferensbidrag (refereegranskat)abstract
- A numerical and experimental study on the conversion of a biomass particle is carried out to quantify the effect of homogeneous volatile combustion on the biomass pyrolysis. The numerical domain consists of a particle and its surrounding and the model considers detailed chemical kinetic mechanism for reaction of pyrolysis products. A detailed pyrolysis model is employed which provides the composition of pyrolysis products. The effect of gas phase reaction on the conversion time and temperature of the particle is analyzed and it was shown that the gas phase reactions results in shorter pyrolysis time. H2O mole fraction and temperature above a biomass pellet from wheat straw (WS) and stem wood (SW) were experimentally measured using tunable diode laser absorption spectroscopy (TDLAS) while recording the particle mass loss. The TDLAS data were used to validate the numerical model developed for biomass conversion. The results showed that by considering the gas phase reactions a good agreement between the measurement and the model prediction for mass loss and temperature can be achieved. For H2O mole fraction on top of the particle, on the other hand, some discrepancy between the model prediction and the experimental data was observed. Nevertheless, the difference in H2O mole fraction would be much larger by neglecting the gas phase reaction at the particle boundary.
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| 14. |
- Lakew, Ewnetu Bayuh, et al.
(författare)
-
KPI-agnostic Control for Fine-Grained Vertical Elasticity
- 2017
-
Ingår i: 2017 17TH IEEE/ACM INTERNATIONAL SYMPOSIUM ON CLUSTER, CLOUD AND GRID COMPUTING (CCGRID). - : IEEE. - 9781509066117 ; , s. 589-598
-
Konferensbidrag (refereegranskat)abstract
- Applications hosted in the cloud have become indispensable in several contexts, with their performance often being key to business operation and their running costs needing to be minimized. To minimize running costs, most modern virtualization technologies such as Linux Containers, Xen, and KVM offer powerful resource control primitives for individual provisioning - that enable adding or removing of fraction of cores and/or megabytes of memory for as short as few seconds. Despite the technology being ready, there is a lack of proper techniques for fine-grained resource allocation, because there is an inherent challenge in determining the correct composition of resources an application needs, with varying workload, to ensure deterministic performance.This paper presents a control-based approach for the management of multiple resources, accounting for the resource consumption, together with the application performance, enabling fine-grained vertical elasticity. The control strategy ensures that the application meets the target performance indicators, consuming as less resources as possible. We carried out an extensive set of experiments using different applications – interactive with response-time requirements, as well as non-interactive with throughput desires – by varying the workload mixes of each application over time. The results demonstrate that our solution precisely provides guaranteed performance while at the same time avoiding both resource over- and under-provisioning.
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| 15. |
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| 16. |
- Papadopoulos, Alessandro, et al.
(författare)
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Power-aware cloud brownout : Response time and power consumption control
- 2017
-
Ingår i: 2017 IEEE 56th Annual Conference on Decision and Control (CDC). - : IEEE. - 9781509028733 - 9781509028726 - 9781509028740 ; , s. 2686-2691
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Konferensbidrag (refereegranskat)abstract
- Cloud computing infrastructures are powering most of the web hosting services that we use at all times. A recent failure in the Amazon cloud infrastructure made many of the website that we use on a hourly basis unavailable1. This illustrates the importance of cloud applications being able to absorb peaks in workload, and at the same time to tune their power requirements to the power and energy capacity offered by the data center infrastructure. In this paper we combine an established technique for response time control — brownout — with power capping. We use cascaded control to take into account both the need for predictability in the response times (the inner loop), and the power cap (the outer loop). We execute tests on real machines to determine power usage and response times models and extend an existing simulator. We then evaluate the cascaded controller approach with a variety of workloads and both open- and closed-loop client models.
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| 17. |
- Tärneberg, William, et al.
(författare)
-
Distributed Approach to the Holistic Resource Management of a Mobile Cloud Network
- 2017
-
Ingår i: International Conference of Fog and Edge Computing. - 9781509030477
-
Konferensbidrag (refereegranskat)abstract
- The Mobile Cloud Network is an emerging cost and capacity heterogeneous distributed cloud topological paradigm that aims to remedy the application performance constraints imposed by centralised cloud infrastructures. A centralised cloud infrastructure and the adjoining Telecom network will struggle to accommodate the exploding amount of traffic generated by forthcoming highly interactive applications. Cost effectively managing a Mobile Cloud Network computing infrastructure while meeting individual application’s performance goals is non- trivial and is at the core of our contribution. Due to the scale of a Mobile Cloud Network, a centralised approach is infeasible. Therefore, in this paper a distributed algorithm that addresses these challenges is presented. The presented approach works towards meeting individual application’s performance objectives, constricting system-wide operational cost, and mitigating re- source usage skewness. The presented distributed algorithm does so by iteratively and independently acting on the objectives of each component with a common heuristic objective function. Sys- tematic evaluations reveal that the presented algorithm quickly converges and performs near optimal in terms of system-wide operational cost and application performance, and significantly outperforms similar na ̈ıve and random methods.
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| 18. |
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| 19. |
- Dürango, Jonas, et al.
(författare)
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A control theoretical approach to non-intrusive geo-replication for cloud services
- 2016
-
Ingår i: 2016 IEEE 55TH CONFERENCE ON DECISION AND CONTROL (CDC). - : IEEE. - 9781509018376 ; , s. 1649-1656
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Konferensbidrag (refereegranskat)abstract
- Complete data center failures may occur due to disastrous events such as earthquakes or fires. To attain robustness against such failures and reduce the probability of data loss, data must be replicated in another data center sufficiently geographically separated from the original data center. Implementing geo-replication is expensive as every data update operation in the original data center must be replicated in the backup. Running the application and the replication service in parallel is cost effective but creates a trade-off between potential replication consistency and data loss and reduced application performance due to network resource contention. We model this trade-off and provide a control-theoretical solution based on Model Predictive Control to dynamically allocate network bandwidth to accommodate the objectives of both replication and application data streams. We evaluate our control solution through simulations emulating the individual services, their traffic flows, and the shared network resource. The MPC solution is able to maintain a consistent performance over periods of persistent overload, and is quickly able to indiscriminately recover once the system return to a stable state. Additionally, the MPC balances the two objectives of consistency and performance according to the proportions specified in the objective function.
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| 20. |
- Mehta, Amardeep, 1985-, et al.
(författare)
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How beneficial are intermediate layer Data Centers in Mobile Edge Networks?
- 2016
-
Ingår i: Workshops on Fog and Mobile Edge Computing at Foundations and Applications of Self* Systems. - 9781509036516 ; , s. 222-229
-
Konferensbidrag (refereegranskat)abstract
- To reduce the congestion due to the future bandwidth- hungry applications in domains such as Health care, Internet of Things (IoT), etc., we study the benefit of introducing additional Data Centers (DCs) closer to the network edge for the optimal application placement. Our study shows that the edge layer DCs in a Mobile Edge Network (MEN) infrastructure is cost beneficial for the bandwidth-hungry applications having their strong demand locality and in the scenarios where large capacity is deployed at the edge layer DCs. The cost savings for such applications can go up to 67%. Additional intermediate layer DCs close to the root DC can be marginally cost beneficial for the compute intensive applications with medium or low demand locality. Hence, a Telecom Network Operator should start building an edge DC first having capacity up to hundreds of servers at the network edge to cater the emerging bandwidth- hungry applications and to minimize its operational cost.
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| 21. |
- Ali-Eldin, Ahmed, 1985-, et al.
(författare)
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Analysis and characterization of a Video-on-Demand service workload
- 2015
-
Ingår i: Proceedings of the 6th ACM Multimedia Systems Conference, MMSys 2015. - New York, NY, USA : ACM Digital Library. - 9781450333511 ; , s. 189-200
-
Konferensbidrag (refereegranskat)abstract
- Video-on-Demand (VoD) and video sharing services accountfor a large percentage of the total downstream Internet traf-fic. In order to provide a better understanding of the loadon these services, we analyze and model a workload tracefrom a VoD service provided by a major Swedish TV broad-caster. The trace contains over half a million requests gener-ated by more than 20000 unique users. Among other things,we study the request arrival rate, the inter-arrival time, thespikes in the workload, the video popularity distribution, thestreaming bit-rate distribution and the video duration distri-bution. Our results show that the user and the session ar-rival rates for the TV4 workload does not follow a Poissonprocess. The arrival rate distribution is modeled using a log-normal distribution while the inter-arrival time distributionis modeled using a stretched exponential distribution. Weobserve the “impatient user” behavior where users abandonstreaming sessions after minutes or even seconds of startingthem. Both very popular videos and non-popular videos areparticularly affected by impatient users. We investigate ifthis behavior is an invariant for VoD workloads.
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| 22. |
- Andersson, Alina, et al.
(författare)
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Sufficient Conditions for Dynamic Stabilization of 3-State Moore-Greitzer Compressor Model
- 2015
-
Ingår i: 2015 IEEE 54th Annual Conference on Decision and Control (CDC). - 9781479978861 - 9781479978847 ; , s. 4394-4399
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Konferensbidrag (refereegranskat)abstract
- We consider the classical 3-state Moore-Greitzer model, which is commonly used for approximating dynamics of deviations of flow and pressure variables in an axial compressor from their nominal steady-state values. The linearization of the nonlinear system is not controllable and, therefore, even local asymptotic stability cannot be achieved using methods of linear control theory. We propose a family of parametrized partialstate feedback control laws and derive sufficient conditions to guarantee global asymptotic stability of the closed-loop system. The stability analysis uses the integral quadratic constraints technique for the case of non-strict frequency condition and novel arguments for characterization of omega-limit sets.
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| 23. |
- Benedek, Hunor, et al.
(författare)
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Strategies for quality assurance of intensity modulated radiation therapy
- 2015
-
Ingår i: 8TH INTERNATIONAL CONFERENCE ON 3D RADIATION DOSIMETRY (IC3DDOSE). - : Institute of Physics (IOP). ; 573, s. 012015-012015
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Konferensbidrag (refereegranskat)abstract
- In late 2011 The Swedish Society of Radiation Physics formed a working group to concentrate on the Quality Assurance of modern radiation therapy techniques. The given task was to identify and summarise the different QA strategies in Sweden and also the international recommendations. This was used to formulate recommendations for practical guidelines within Sweden. In this paper a brief summery of the group's work is presented. All the Swedish radiation therapy centres do a pre treatment verification measurement as QA for every new IMRT and VMAT plan. Physicists do it and they believe it to be time consuming. A general standpoint from all the centres was that new guidelines and legislation is needed to allow QA that does not require a measurement. Based on various international publications and recommendations the working group has presented two strategies, one where all new plans are checked through measurement and one where no measurement is needed. The measurement-based strategy is basically the same as the one used today with an extended machine QA part. The other presented strategy is process oriented where all the different parts of the treatment chain are checked separately. The final report can be found in Swedish on http://www.radiofysik.org.
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| 24. |
- Desmeurs, David, et al.
(författare)
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Event-Driven Application Brownout : Reconciling High Utilization and Low Tail Response Times
- 2015
-
Ingår i: 2015 International Conference on Cloud and Autonomic Computing (ICCAC). - New York : IEEE Computer Society. - 9781467395663 ; , s. 1-12
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Konferensbidrag (refereegranskat)abstract
- Data centers currently waste a lot of energy, due to lack of energy proportionality and low resource utilization, the latter currently being necessary to ensure application responsiveness. To address the second concern we propose a novel application-level technique that we call event-driven Brownout. For each request, i.e., in an event-driven manner, the application can execute some optional code that is not required for correct operation but desirable for user experience, and does so only if the number of pending client requests is below a given threshold. We propose several autonomic algorithms, based on control theory and machine learning, to automatically tune this threshold based on measured application 95th percentile response times. We evaluate our approach using the RUBiS benchmark which shows a 11-fold improvement in maintaining response-time close to a set-point at high utilization compared to competing approaches. Our contribution is opening the path to more energy efficient data-centers, by allowing applications to keep response times close to a set-point even at high resource utilization.
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| 25. |
- Krzywda, Jakub, et al.
(författare)
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Telco Clouds: Modelling and Simulation
- 2015
-
Ingår i: Proceedings of the 5th International Conference on Cloud Computing and Services Science. - : SciTePress. - 9789897581045 ; , s. 597-609
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Konferensbidrag (refereegranskat)abstract
- In this paper, we propose a telco cloud meta-model that can be used to simulate different infrastructure con- figurations and explore their consequences on the system performance and costs. To achieve this, we analyse current telecommunication and data centre infrastructure paradigms, describe the architecture of the telco cloud and detail the benefits of merging both infrastructures in a unified system. Next, we detail the dynamics of the telco cloud and identify the components that are the most relevant from the perspective of modelling performance and cost. A number of well established simulation technologies exist for most of the telco cloud components, we thus proceed with surveying existing models in an attempt to construct a suitable composite meta-model. Finally, we present a showcase scenario to demonstrate the scope of our telco cloud simulator.
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| 26. |
- Mehta, Amardeep, et al.
(författare)
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Online Spike Detection in Cloud Workloads
- 2015
-
Ingår i: [Host publication title missing]. - New York : IEEE Computer Society. ; , s. 446-451, s. 446-451
-
Konferensbidrag (refereegranskat)abstract
- We investigate methods for detection of rapid workload increases (load spikes) for cloud workloads. Such rapid and unexpected workload spikes are a main cause for poor performance or even crashing applications as the allocated cloud resources become insufficient. To detect the spikes early is fundamental to perform corrective management actions, like allocating additional resources, before the spikes become large enough to cause problems. For this, we propose a number of methods for early spike detection, based on established techniques from adaptive signal processing. A comparative evaluation shows, for example, to what extent the different methods manage to detect the spikes, how early the detection is made, and how frequently they falsely report spikes.
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| 27. |
- Andersson, Alina, et al.
(författare)
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Robustness of the Moore-Greitzer Compressor Model's Surge Subsystem with New Dynamic Output Feedback Controllers
- 2014. - 3
-
Ingår i: 19th IFAC World Congress. - : Elsevier. - 2405-8963. - 9783902823625 ; 47, s. 3690-3695
-
Konferensbidrag (refereegranskat)abstract
- This work presents an extension of a design procedure for dynamic output feedback design for systems with nonlinearities satisfying quadratic constraints. In this work we used an axial gas compressor model described by the 3-state Moore-Greitzer compressor model (MG) that has some challenges for output feedback control design (Planovsky and Nikolaev 1990), (Rubanova 2013). The more general constraints for the investigation of the robustness with respect to parametric uncertainties and measurement noise are shown.
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| 28. |
- Dürango, Jonas, et al.
(författare)
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Control-theoretical load-balancing for cloud applications with brownout
- 2014
-
Ingår i: 2014 IEEE 53RD ANNUAL CONFERENCE ON DECISION AND CONTROL (CDC). - 9781467360906 - 9781479977468 ; , s. 5320-5327
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Konferensbidrag (refereegranskat)abstract
- Cloud applications are often subject to unexpected events like flash crowds and hardware failures. Without a predictable behaviour, users may abandon an unresponsive application. This problem has been partially solved on two separate fronts: first, by adding a self-adaptive feature called brownout inside cloud applications to bound response times by modulating user experience, and, second, by introducing replicas - copies of the applications having the same functionalities - for redundancy and adding a load-balancer to direct incoming traffic. However, existing load-balancing strategies interfere with brownout self-adaptivity. Load-balancers are often based on response times, that are already controlled by the self-adaptive features of the application, hence they are not a good indicator of how well a replica is performing. In this paper, we present novel load-balancing strategies, specifically designed to support brownout applications. They base their decision not on response time, but on user experience degradation. We implemented our strategies in a self-adaptive application simulator, together with some state-of-the-art solutions. Results obtained in multiple scenarios show that the proposed strategies bring significant improvements when compared to the state-of-the-art ones.
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| 29. |
- Gustafson, Carl, et al.
(författare)
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Modeling the cluster decay in mm-wave channels
- 2014
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Ingår i: 8th European Conference on Antennas and Propagation, EuCAP 2014. - 9788890701849 ; , s. 803-807
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Konferensbidrag (refereegranskat)abstract
- © 2014 European Association on Antennas and Propagation.The cluster power is an important parameter for cluster-based wireless channel models. This paper addresses modeling and estimation of the cluster power for wireless channels. A novel way of estimating the cluster decay and cluster fading, where the effects of the noise floor is taken into account, is presented. Due to the noise floor present in the measurement, only a limited number of clusters are available when estimating the cluster decay. It is shown that the estimated cluster decay and cluster fading can be improved if the effects of the noise floor and cluster fading are modeled and taken into account in the estimation step. If the noise floor is not taken into account in the estimation of the cluster decay, the resulting model can overestimate the RMS delay spread. Further, the paper includes estimates of the cluster decay and fading based on measured clusters for an indoor wireless mm-Wave channel in a conference room environment.
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| 30. |
- Klein, Cristian, 1985-, et al.
(författare)
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Brownout : Building More Robust Cloud Applications
- 2014
-
Ingår i: 36th International Conference on Software Engineering (ICSE 2014). - New York, NY, USA : ACM Digital Library. ; , s. 700-711
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Konferensbidrag (refereegranskat)abstract
- Self-adaptation is a first class concern for cloud applications, which should be able to withstand diverse runtime changes. Variations are simultaneously happening both at the cloud infrastructure level - for example hardware failures - and at the user workload level - flash crowds. However, robustly withstanding extreme variability, requires costly hardware over-provisioning. In this paper, we introduce a self-adaptation programming paradigm called brownout. Using this paradigm, applications can be designed to robustly withstand unpredictable runtime variations, without over-provisioning. The paradigm is based on optional code that can be dynamically deactivated through decisions based on control theory. We modified two popular web application prototypes - RUBiS and RUBBoS - with less than 170 lines of code, to make them brownout-compliant. Experiments show that brownout self-adaptation dramatically improves the ability to withstand flash-crowds and hardware failures.
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| 31. |
- Klein, Cristian, 1985-, et al.
(författare)
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Improving Cloud Service Resilience using Brownout-Aware Load-Balancing
- 2014
-
Ingår i: 2014 IEEE 33rd International Symposium On Reliable Distributed Systems (SRDS). - : IEEE Computer Society. - 9781479955848 ; , s. 31-40, s. 31-40
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Konferensbidrag (refereegranskat)abstract
- We focus on improving resilience of cloud services (e.g., e-commerce website), when correlated or cascading failures lead to computing capacity shortage. We study how to extend the classical cloud service architecture composed of a load-balancer and replicas with a recently proposed self-adaptive paradigm called brownout. Such services are able to reduce their capacity requirements by degrading user experience (e.g., disabling recommendations).Combining resilience with the brownout paradigm is to date an open practical problem. The issue is to ensure that replica self-adaptivity would not confuse the load-balancing algorithm, overloading replicas that are already struggling with capacity shortage. For example, load-balancing strategies based on response times are not able to decide which replicas should be selected, since the response times are already controlled by the brownout paradigm.In this paper we propose two novel brownout-aware load-balancing algorithms. To test their practical applicability, we extended the popular lighttpd web server and load-balancer, thus obtaining a production-ready implementation. Experimental evaluation shows that the approach enables cloud services to remain responsive despite cascading failures. Moreover, when compared to Shortest Queue First (SQF), believed to be near-optimal in the non-adaptive case, our algorithms improve user experience by 5%, with high statistical significance, while preserving response time predictability.
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| 32. |
- Maggio, Martina, et al.
(författare)
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Control strategies for predictable brownouts in cloud computing
- 2014
-
Ingår i: Proceedings of the 19th World Congress, The International Federation of Automatic Control. - : Elsevier. - 9783902823625 ; , s. 689-694
-
Konferensbidrag (refereegranskat)abstract
- Cloud computing is an application hosting model providing the illusion of infinite computing power. However, even the largest datacenters have finite computing capacity, thus cloud infrastructures have experienced overload due to overbooking or transient failures. The topic of this paper is the comparison of different control strategies to mitigate overload for datacenters, that assume that the running cloud applications are cooperative and help the infrastructure in recovering from critical events. Specifically, the paper investigates the behavior of different controllers when they have to keep the average response time of a cloud application below a certain threshold by acting on the probability of serving requests with optional computations disabled, where the pressure exerted by each request on the infrastructure is diminished, at the expense of user experience.
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| 33. |
- Andersson, Alina, et al.
(författare)
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Analytic Parameterization of Stabilizing Controllers for the Surge Subsystem of the Moore-Greitzer Compressor Model
- 2013
-
Ingår i: Proc. 2013 American Control Conference (ACC2013). - 0743-1619. - 9781479901777 ; , s. 5257-5262
-
Konferensbidrag (refereegranskat)abstract
- This paper is based on a new procedure for dynamic output feedback design for systems with nonlinearities satisfying quadratic constraints. The new procedure is motivated by the challenges of output feedback control design for the 3-state Moore-Greitzer compressor model. First, we use conditions for stability of a transformed system and the associated matching conditions to find the data of the stabilizing controllers for the surge subsystem. Second, using the set of stabilizing controllers satisfying the given constraints for the closed-loop system with the dynamic output feedback controller we made optimization over the parameter set. We present the data of the stabilizing controllers and the new constraints for the corresponding parameters. The contributions in this paper are simplified conditions for the synthesis and optimization over the control parameter set.
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| 34. |
- Kihl, Maria, et al.
(författare)
-
The Challenge of Cloud Control
- 2013
-
Ingår i: The 8th International Workshop on Feedback Computing (Feedback Computing '13).
-
Konferensbidrag (refereegranskat)abstract
- Today’s cloud data center infrastructures are not even near being able to cope with the enormous and rapidly vary-ing capacity demands that will be reality in a near future. So far, very little is understood about how to transform today’s data centers (being large, power-hungry facilities, and operated through heroic efforts by numerous adminis-trators) into a self-managed, dynamic, and dependable infrastructure, constantly delivering expected QoS with rea-sonable operation costs and acceptable carbon footprint for large-scale services with sometimes dramatic variations in capacity demands. In this paper, we discuss some of the major challenges for resource-optimized cloud data cen-ter. We propose a new research area called Cloud Control, which is a control theoretic approach to a range of cloud management problems, aiming to transform today´s static and energy consuming cloud data centers into self-managed, dynamic, and dependable infrastructures, constantly delivering expected quality of service with acceptable operation costs and carbon footprint for large-scale services with varying capacity demands.
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| 35. |
- Klein, Cristian, 1985-, et al.
(författare)
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Introducing Service-level Awareness in the Cloud
- 2013
-
Ingår i: Proceedings of the 4th annual Symposium on Cloud Computing. - New York, NY, USA : Association for Computing Machinery (ACM). - 9781450324281
-
Konferensbidrag (refereegranskat)
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| 36. |
- Ali-Eldin, Ahmed, et al.
(författare)
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Efficient provisioning of bursty scientific workloads on the cloud using adaptive elasticity control
- 2012
-
Ingår i: Proceedings of the 3rd workshop on Scientific Cloud Computing Date. - New York, NY, USA : Association for Computing Machinery (ACM). - 9781450313407 - 145031340X ; , s. 31-40
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Konferensbidrag (refereegranskat)abstract
- Elasticity is the ability of a cloud infrastructure to dynamically change theamount of resources allocated to a running service as load changes. We build anautonomous elasticity controller that changes the number of virtual machinesallocated to a service based on both monitored load changes and predictions offuture load. The cloud infrastructure is modeled as a G/G/N queue. This modelis used to construct a hybrid reactive-adaptive controller that quickly reactsto sudden load changes, prevents premature release of resources, takes intoaccount the heterogeneity of the workload, and avoids oscillations. Using simulations with Web and cluster workload traces, we show that our proposed controller lowers the number of delayed requests by a factor of 70 for the Web traces and 3 for the cluster traces when compared to a reactive controller. Ourcontroller also decreases the average number of queued requests by a factor of 3 for both traces, and reduces oscillations by a factor of 7 for the Web traces and 3 for the cluster traces. This comes at the expense of between 20% and 30% over-provisioning, as compared to a few percent for the reactive controller.
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| 37. |
- Andersson, Martin, et al.
(författare)
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An upgrade of the internal dosimetry computer program IDAC
- 2012
-
Ingår i: Medical Physics in the Baltic States. - : Kaunas University of Technology. - 1822-5721. ; , s. 120-123
-
Konferensbidrag (refereegranskat)abstract
- A full update of the internal dosimetry computer program IDAC has been conducted. The new update is based on new and more accurate computational phantoms to calculate effective dose and absorbed dose to organs and tissues. The new ICRP Adult Reference Computational Phantoms has been adopted as well as the latest of the ICRP standardized biokinetic models. The updated computer program includes a user-friendly graphical user interface.
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| 38. |
- Bååth, Rasmus, et al.
(författare)
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The Subjective Difficulty of Tapping to a Slow Beat
- 2012
-
Ingår i: Proceedings of the 12th International Conference on Music Perception and Cognition and the 8th Triennial Conference of the European Society for the Cognitive Sciences of Music.. ; , s. 82-85
-
Konferensbidrag (refereegranskat)
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| 39. |
- Mattsson, Sören, et al.
(författare)
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Current activities in the ICRP concerning estimation of radiation doses to patients from radiopharmaceuticals for diagnostic use
- 2011
-
Ingår i: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 317, s. 012008-012008
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Konferensbidrag (refereegranskat)abstract
- A Task Group within the ICRP Committees 2 and 3 is continuously working to improve absorbed dose estimates to patients investigated with radiopharmaceuticals. The work deals with reviews of the literature, initiation of new or complementary studies of the biokinetics of a compound and dose estimates. Absorbed dose calculations for organs and tissues have up to now been carried out using the MIRD formalism. There is still a lack of necessary biokinetic data from measurements in humans. More time series obtained by nuclear medicine imaging techniques such as whole-body planar gamma-camera imaging, SPECT or PET are highly desirable for this purpose. In 2008, a new addendum to ICRP Publication 53 was published under the name of ICRP Publication 106 containing biokinetic data and absorbed dose information to organs and tissues of patients of various ages for radiopharmaceuticals in common use. That report also covers a number of generic models and realistic maximum models covering other large groups of substances (e.g. "(123)I-brain receptor substances"). Together with ICRP Publication 80, most radiopharmaceuticals in clinical use at the time of publication were covered except the radioiodine labeled compounds for which the ICRP dose estimates are still found in Publication 53. There is an increasing use of new radiopharmaceuticals, especially PET-tracers and the TG has recently finished its work with biokinetic and dosimetric data for (18)F-FET, (18)F-FLT and (18)F-choline. The work continues now with new data for (11)C-raclopride, (11)C-PiB and (123)I-ioflupan as well as re-evaluation of published data for (82)Rb-chloride, (18)F-fluoride and radioiodide. This paper summarises published ICRP-information on dose to patients from radiopharmaceuticals and gives some preliminary data for substances under review.
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| 40. |
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| 41. |
- Murray, V., et al.
(författare)
-
The molecular basis of thrombolysis and its clinical application in stroke
- 2010
-
Ingår i: Journal of Internal Medicine. - : Wiley. - 0954-6820 .- 1365-2796. ; 267:2, s. 191-208
-
Konferensbidrag (refereegranskat)abstract
- The rationale for thrombolysis, the most promising pharmacological approach in acute ischaemic stroke, is centred on the principal cause of most ischaemic strokes: the thrombus that occludes the cerebral artery, and renders part of the brain ischaemic. The occluding thrombus is bound together within fibrin. Fibrinolysis acts by activation of plasminogen to plasmin; plasmin splits fibrinogen and fibrin and lyses the clot, which then allows reperfusion of the ischaemic brain. Thrombolytic agents include streptokinase (SK) and recombinant tissue-type plasminogen activator (rt-PA) amongst others under test or development. SK is nonfibrin-specific, has a longer half-life than tissue-type plasminogen activator (t-PA), prevents re-occlusion and is degraded enzymatically in the circulation. rt-PA is more fibrin-specific and clot-dissolving, and is metabolized during the first passage in the liver. In animal models of ischaemic stroke, the effects of rt-PA are remarkably consistent with the effects seen in human clinical trials. For clinical application, some outcome data from the Cochrane Database of Systematic Reviews which includes all randomized evidence available on thrombolysis in man were used. Trials included tested urokinase, SK, rt-PA, pro-urokinase, or desmoteplase. The chief immediate hazard of thrombolytic therapy is fatal intracranial bleeding. However, despite the risk, the human trial data suggest the immediate hazards and the apparent substantial scope for net benefit of thrombolytic therapy given up to 6 h of acute ischaemic stroke. So far the fibrin-specific rt-PA is the only agent to be approved for use in stroke. This may be due to its short half-life and its absence of any specific amount of circulating fibrinogen degradation products, thereby leaving platelet function intact. The short half-life does not leave rt-PA without danger for haemorrhage after the infusion. Due to its fibrin-specificity, it can persist within a fibrin-rich clot for one or more days. The molecular mechanisms with regards to fibrin-specificity in thrombolytic agents should, if further studied, be addressed in within-trial comparisons. rt-PA has antigenic properties and although their long-term clinical relevance is unclear there should be surveillance for allergic reactions in relation to treatment. Although rt-PA is approved for use in selected patients, there is scope for benefit in a much wider variety of patients. A number of trials are underway to assess which additional patients - beyond the age and time limits of the current approval - might benefit, and how best to identify them.
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| 42. |
- Nordström, Fredrik, et al.
(författare)
-
3D geometric gel dosimetry verification of intraprostatic fiducial guided hypofractionated radiotherapy of prostate cancer
- 2010
-
Ingår i: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6596. ; 250, s. 287-291
-
Konferensbidrag (refereegranskat)abstract
- This pre-study is aimed to investigate the feasibility of a normoxic polyacrylamide gel (nPAG) dosimeter with implanted gold fiducials to evaluate the geometric precision, including setup correction strategies, in the delivery of hypofractionated treatments. For this purpose a phantom consisting of three parts was constructed: (1) the patient simulating volume, providing realistic scatter conditions and weight, (2) a bottle containing the active dosimetric volume and (3) the gold fiducials and the fiducial support structure. A 6.1 Gy prostate IMRT treatment was delivered to the phantom using the sliding-window technique. The phantom was positioned prior to the treatment using the implanted fiducials and kV on-board imaging. An overlay of the 95% isosurface of the TPS calculated dose distribution and the measured dose distribution using gel showed good agreement. The clinical target volume (CTV) was well centred inside the 95% isodose surface of the measured volume. It was shown for the evaluated case that the use of on-board imaging and integrated setup correction tools could be used to compensate for a deliberately introduced offset in CTV position. The study showed that MRI based nPAG gel dosimetry can be used to verify setup correction procedures using implanted gold fiducials.
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| 43. |
- Shiriaev, Anton S., et al.
(författare)
-
Criteria for Global Stability of Coupled Systems with Application to Robust Output Feedback Design for Active Surge Control
- 2009
-
Ingår i: Proc. 2009 IEEE Multi-conference on Systems and Control (MSC 2009). ; , s. 1021-1026
-
Konferensbidrag (refereegranskat)abstract
- The well-known and commonly accepted finite dimensional model qualitatively describing surge instabilities in centrifugal (and axial) compressors is considered. The problem of global output feedback stabilization for it is solved. The solution relies on two new criteria for global stability proposed for a class of nonlinear systems exploiting quadratic constraints for infinite sector nonlinearities. Two families of robust output feedback controllers are proposed. Controllers from the first family ensure global exponential stabilization. The ones from the second family provide integral action but only ensure local exponential and global asymptotic stability. Performance is verified by simulations.
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| 44. |
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| 45. |
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| 46. |
- Shiriaev, Anton, et al.
(författare)
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Separation Principle for a Class of Nonlinear Feedback Systems Augmented with Observers
- 2008
-
Ingår i: Proc. 17th IFAC2008 World Congress. ; , s. 6196-6201, s. 6196-6201
-
Konferensbidrag (refereegranskat)abstract
- The paper suggests conditions for presence of quadratic Lyapunov functions for nonlinear observer based feedback systems with an input nonlinearity in the feedback path. Provided that the system using state feedback satisfies the circle criterion (i.e., when all states can be measured), we show that stability of the extended system with output feedback control from a (full state) Luenberger-type observer may be concluded using the circle criterion. As another result, we state a separation principle for a class of feedback systems with an input nonlinearity.When only local stability results can be stated, our method provides an estimate of the region of attraction.
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| 47. |
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| 48. |
- Freidovich, Leonid, et al.
(författare)
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Friction Compensation Based on LuGre Model
- 2006
-
Ingår i: Proc. 45th IEEE Conf. Decision & Control (CDC 2006). - New York : IEEE. ; , s. 3837-3842
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Konferensbidrag (refereegranskat)abstract
- We consider a tracking problem for mechanical systems. It is assumed that feedback controller is designed neglecting some disturbances, which could be approximately modeled by a dynamic LuGre friction model. We are interested to derive an additive observer-based compensator to annihilate or reduce the influence of such a disturbance. We exploit a recently suggested approach for observer design for LuGre friction-model-based compensation. In order to follow this technique, it is necessary to know the Lyapunov function for the unperturbed system, parameters of the dynamic friction model, and to have certain structural property satisfied. The case when this property is passivity with respect to the matching disturbance related to the given Lyapunov function is illustrated in the paper with an example of a DC-motor. The main contribution is some new insights into numerical real time implementation of friction compensators for various LuGre type models. The other contribution, built upon the main one, is experimental verification of the suggested observer design procedure.
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| 49. |
- Hellström, Lars
(författare)
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Rewriting in operads and PROPs
- 2006
-
Ingår i: Journal of nonlinear mathematical physics. - Luleå : Norbert Euler. - 1776-0852 .- 1402-9251. ; , s. 66-75
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Konferensbidrag (refereegranskat)abstract
- This paper is an informal collection of observations on how established rewriting techniques can be applied to or need to be adapted for use in non-associative algebras, operads, and PROPs.
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| 50. |
- Shiriaev, Anton, et al.
(författare)
-
Coordinating control for a fleet of underactuated ships
- 2006
-
Ingår i: GROUP COORDINATION AND COOPERATIVE CONTROL. - Berlin/Heidelberg : Springer-Verlag. - 3540334688 ; 336, s. 233-250
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Konferensbidrag (refereegranskat)abstract
- We consider design of coordinating controllers for a fleet of underactuated ships. Each ship is modeled as a mechanical system with 3 degrees of freedom and 2 control inputs, which are the propeller thrust and the angle of the rudder; presence of lumped environmental forces is assumed. The proposed motion planning procedure relies. on properties of an auxiliary explicitly constructed second order dynamical system. We propose a procedure for motion planning for the whole fleet and for design of a coordinating feedback controller, which stabilizes the motion. In the case when geometric paths for ship motions are given, following our approach, we obtain a description of all feasible motions of the fleet along these paths. In addition, it is shown how to design controllers to counteract environmental forces while remaining on the paths. As a side result, we provide some modifications and give some insights into the weather optimal positioning control design, introduced in [1] for a fully actuated ship model.
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