| 1. |
- Abghari, Shahrooz, et al.
(author)
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Outlier Detection for Video Session Data Using Sequential Pattern Mining
- 2018
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In: ACM SIGKDD Workshop On Outlier Detection De-constructed.
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Conference paper (peer-reviewed)abstract
- The growth of Internet video and over-the-top transmission techniqueshas enabled online video service providers to deliver highquality video content to viewers. To maintain and improve thequality of experience, video providers need to detect unexpectedissues that can highly affect the viewers’ experience. This requiresanalyzing massive amounts of video session data in order to findunexpected sequences of events. In this paper we combine sequentialpattern mining and clustering to discover such event sequences.The proposed approach applies sequential pattern mining to findfrequent patterns by considering contextual and collective outliers.In order to distinguish between the normal and abnormal behaviorof the system, we initially identify the most frequent patterns. Thena clustering algorithm is applied on the most frequent patterns.The generated clustering model together with Silhouette Index areused for further analysis of less frequent patterns and detectionof potential outliers. Our results show that the proposed approachcan detect outliers at the system level.
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| 2. |
- Collange, Denis, et al.
(author)
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User Impatience and Network Performance
- 2012
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Conference paper (peer-reviewed)abstract
- In this work, we analyze from passive measurements the correlations between the user-induced interruptions of TCP connections and different end-to-end performance metrics. The aim of this study is to assess the possibility for a network operator to take into account the customers' experience for network monitoring. We first observe that the usual connection-level performance metrics of the interrupted connections are not very different, and sometimes better than those of normal connections. However, the request-level performance metrics show stronger correlations between the interruption rates and the network quality-of-service. Furthermore, we show that the user impatience could also be used to characterize the relative sensitivity of data applications to various network performance metrics.
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| 3. |
- Iqbal, Muhammad Imran, et al.
(author)
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Spatio-Temporal Quality of Experience Trade-offs for Mobile Imaging Applications
- 2010
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Conference paper (peer-reviewed)abstract
- In this paper, we focus on mobile images given in JPEG2000 format and evaluate their spatio-temporal Quality of Experience (QoE). In particular, the trade-of between spatial QoE supported by progressive source encoding and temporal QoE related to network delay as well as initial transmission delay is examined.
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| 4. |
- Islam, Nazrul, et al.
(author)
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In Small Chunks or All at Once? User Preferences of Network Delays in Web Browsing Sessions
- 2014
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Conference paper (peer-reviewed)abstract
- The time-critical tasks on the Internet are increasing. The delays in these tasks can have severe implications on the Quality of Experience (QoE) of a service. Therefore, networks require smart user-centric resource management mechanisms to reduce the impact of these delays on QoE. For this, a better understanding of the user preferences with regards to service performance is a prerequisite. In this paper, we present user responses to the three different distributions of delays, occurring during shopping sessions on the Web. By keeping the overall waiting time of the sessions same, we show how the users respond differently to the different set of delays. We analyzed the user responses and found that, the users prefer small frequently occurring delays as compared to the long rarely occurring delays within a task-based session.
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| 5. |
- Lorentzen, Charlott, et al.
(author)
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On user perception of web login : a study on QoE in the context of security
- 2010
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Conference paper (peer-reviewed)abstract
- From the user point of view, security has shown to be ambivalent; on one hand it is felt necessary, but on the other hand it is felt disturbing. Authentication solutions, for instance, are designed to keep undesired and unauthorized users out; however, allowed users need to spend some effort and waiting time when logging into a system. The question remains to which extent this effort is perceived as positive as security is increased, or negative through the waiting time spent in the process. Excessive waiting times imply the risk of user churn. As there is a lack of such studies, this paper investigates user perception (Quality of Experience, QoE) of the response times (Quality of Service, QoS) of a web authentication procedure, in particular a login to a community web page. Comparing the results to well-known user perception of web performance, we show that the users perceive logins in a similar way as standard web pages, which means that similar limits on user patience apply. The derived QoE-QoS relationship, an exponential function, serves then as the basis for assessing the performance of authentication algorithms in the domain of user acceptability.
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| 6. |
- Micah, Angela E., et al.
(author)
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Tracking development assistance for health and for COVID-19 : a review of development assistance, government, out-of-pocket, and other private spending on health for 204 countries and territories, 1990-2050
- 2021
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In: The Lancet. - : Elsevier. - 0140-6736 .- 1474-547X. ; 398:10308, s. 1317-1343
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Research review (peer-reviewed)abstract
- Background The rapid spread of COVID-19 renewed the focus on how health systems across the globe are financed, especially during public health emergencies. Development assistance is an important source of health financing in many low-income countries, yet little is known about how much of this funding was disbursed for COVID-19. We aimed to put development assistance for health for COVID-19 in the context of broader trends in global health financing, and to estimate total health spending from 1995 to 2050 and development assistance for COVID-19 in 2020. Methods We estimated domestic health spending and development assistance for health to generate total health-sector spending estimates for 204 countries and territories. We leveraged data from the WHO Global Health Expenditure Database to produce estimates of domestic health spending. To generate estimates for development assistance for health, we relied on project-level disbursement data from the major international development agencies' online databases and annual financial statements and reports for information on income sources. To adjust our estimates for 2020 to include disbursements related to COVID-19, we extracted project data on commitments and disbursements from a broader set of databases (because not all of the data sources used to estimate the historical series extend to 2020), including the UN Office of Humanitarian Assistance Financial Tracking Service and the International Aid Transparency Initiative. We reported all the historic and future spending estimates in inflation-adjusted 2020 US$, 2020 US$ per capita, purchasing-power parity-adjusted US$ per capita, and as a proportion of gross domestic product. We used various models to generate future health spending to 2050. Findings In 2019, health spending globally reached $8. 8 trillion (95% uncertainty interval [UI] 8.7-8.8) or $1132 (1119-1143) per person. Spending on health varied within and across income groups and geographical regions. Of this total, $40.4 billion (0.5%, 95% UI 0.5-0.5) was development assistance for health provided to low-income and middle-income countries, which made up 24.6% (UI 24.0-25.1) of total spending in low-income countries. We estimate that $54.8 billion in development assistance for health was disbursed in 2020. Of this, $13.7 billion was targeted toward the COVID-19 health response. $12.3 billion was newly committed and $1.4 billion was repurposed from existing health projects. $3.1 billion (22.4%) of the funds focused on country-level coordination and $2.4 billion (17.9%) was for supply chain and logistics. Only $714.4 million (7.7%) of COVID-19 development assistance for health went to Latin America, despite this region reporting 34.3% of total recorded COVID-19 deaths in low-income or middle-income countries in 2020. Spending on health is expected to rise to $1519 (1448-1591) per person in 2050, although spending across countries is expected to remain varied. Interpretation Global health spending is expected to continue to grow, but remain unequally distributed between countries. We estimate that development organisations substantially increased the amount of development assistance for health provided in 2020. Continued efforts are needed to raise sufficient resources to mitigate the pandemic for the most vulnerable, and to help curtail the pandemic for all. Copyright (C) 2021 The Author(s). Published by Elsevier Ltd.
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| 7. |
- Minhas, Tahir Nawaz, et al.
(author)
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Evaluation of throughput performance of traffic shapers
- 2011
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Conference paper (peer-reviewed)abstract
- Traffic shapers are used by researchers to emulate the behavior of networks and applications in test environments, typically with user-defined traffic shaping parameters such as throughput and loss. Also, traffic shapers are used for the enforcement of SLA, so they are of interest for Internet Service Providers. However, output given by traffic shapers may not be as accurate as desired. Therefore, it is important to assess the accuracy of the implementation of traffic shapers. In this paper, we evaluate two traffic shapers with regard to the performance of their throughput shaping. For this evaluation, traces were collected. The properties of the resulting throughput at the outlet of the shaper are compared to the properties of the throughput at the inlet in combination with the preset shaper parameters. In this sense, we also compare shapers installed on Advance Micro Devices (AMD) and Intel platforms, and we use different PDU sizes and load levels to test the influence of those parameters on the shaping. We are furthermore able to deduct internal shaper parameters such as packet rate and buffer size from our measurements, and we analyse the statistical properties of the packet departure process. The extensive measurement results in this paper allow for a detailed assessment of the question whether the shaper performance is up to mark for a desired timescale. In general, the performance of both shapers and hardware platforms can be considered satisfactory on the investigated time scales between 1 ms and 1 s, with a slight advantage for NetEm on AMD.
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| 8. |
- Puthan Pisharam, Pradeep, 1983, et al.
(author)
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Defining crash configurations for Powered Two-Wheelers: Comparing ISO 13232 to recent in-depth crash data from Germany, India and China
- 2021
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In: Accident Analysis and Prevention. - : Elsevier BV. - 0001-4575. ; 151
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Journal article (peer-reviewed)abstract
- The motorcyclist safety standard ISO 13232, based on crash data from Europe and the USA from the 1970s, still sets the direction for the development and evaluation of protective measures today. However, it is unclear how relevant the crash configurations in the standard are to present-day motorcycle crashes in Europe, the USA and other parts of the world. We analyzed recent in-depth crash data from Germany, India and China, examining powered two-wheeler (PTW) crash configurations in which at least one police-reported serious injury was present. After assessing the relevance of the ISO's PTW crash configurations to those we found in each country, we suggested new configurations to guide the development of safety systems that would be more effective at reducing PTW-related fatalities and serious injuries. In all three databases, passenger cars were among the top two most frequent collision partners and a car front impacting the side of the PTW was the most common configuration. Notably, although collisions with trucks constituted the most common scenario in India and ground impact (primary collision) was a common scenario in both Germany and India, the ISO did not include either configuration. Further, in three of the seven ISO crash configurations, one of the collision partners is stationary, although stationary collision partners were rare in our data. Our results show that the ISO crash configurations do not represent the most frequent PTW road crashes in Germany, India or China. However, the Chinese database was confined to crashes with a collision partner with four or more wheels. Further, weighting factors for these data were not available, so we could not extrapolate the frequency of the Chinese crash configurations across the entire population. A revised version of the ISO could serve as a basis for a full-scale PTW crash test program. However, the observed differences between countries imply that a single global standard may not be feasible. To optimize the evaluation of a PTW safety system, we recommend the inclusion of configurations which are frequent in the region or country of interest—in addition to common configurations occurring frequently all around the world.
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| 9. |
- Ranmal, Aarti, et al.
(author)
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Rib and sternum fracture risks for restrained occupants in frontal car crashes
- 2024
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In: Traffic Injury Prevention. - 1538-957X .- 1538-9588. ; 25:4, s. 616-622
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Journal article (peer-reviewed)abstract
- Objective Most car occupant fatalities occur in frontal crashes and the thorax is the most frequently injured body region. The objectives of the study were, firstly, to quantify the relation between risk factors (such as speed and occupant age) and rib and sternum fracture injury probability in frontal car crashes, and, secondly, to evaluate whether rib fracture occurrence can predict sternum fractures. Methods Weighted German data from 1999-2021 were used to create the injury risk curves to predict both, at least moderate and at least serious, rib and sternum fracture risks. A contingency table for rib and sternum fractures allowed the calculation of sensitivity, specificity, and precision, as well as testing for the association. Results Elderly occupants (>= 65 years old) had increased rib and sternum fracture risk compared to mid aged occupants (18-64 years old). Besides occupant age, delta-V was always and sex sometimes a significant predictor for skeletal thoracic injury. Sternum fractures were more common than rib fractures and more likely to occur at any given delta-V. Sternum fractures occurred often in isolation. Female occupants were at higher risk than males to sustain at least moderate rib and sternum fractures together and sternum fractures in isolation. Rib and sternum fractures were associated, but low sensitivity and precision show that rib fractures do not predict sternum fractures well. Conclusions Elderly and female occupants were at the highest risk and should be targeted by thoracic injury criteria and thresholds for frontal crash occupant protection. Rib and sternum fractures were not associated. Therefore, sternum fractures need to be predicted and evaluated separately from rib fractures.
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| 10. |
- Shaikh, Junaid, et al.
(author)
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Back to Normal? Impact of Temporally Increasing Network Disturbances on QoE
- 2013
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Conference paper (peer-reviewed)abstract
- Brief episodes of network faults and performance issues adversely affect the user Quality of Experience (QoE). Besides damaging the current opinions of users, these events may also shape user’s future perception of the service. Therefore, it is important to quantify the impact of such events on QoE over time. In this paper, we present our findings on the temporal aspects of user feedback to disturbances on networks. These findings are based on subjective user tests performed in the context of web browsing on an e-commerce website. The results of this study suggest that the QoE drops significantly every time the page load time grows. The after-effects of network disturbances on user QoE remain visible even when the network problems are over, i.e., users do not immediately return to the same level of opinion scores as compared to the corresponding pre-disturbance phase. They tend to remember their recent experiences. Our results also show that there are four segments of users that exist with regards to their feedback to page load times. Network operators may customize their services according to each segment of users to raise the overall QoE. Finally, we show that the exponential relationship provides best fits of QoE and page load times for all segments of users.
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