Blekinge Institute of Technology
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Analysis of the impact of temporal, spatial, and quantization variations on perceptual video quality
No full textThe growing consumer interest in video communication has increased the users'
awareness in the visual quality of the delivered media. This in turn increases,
at the service provider end, the need for intelligent methodologies of optimal
techniques for adapting to varying network conditions. Recent studies show that
constraints on the bandwidth of transmission media should not always be
translated to an increase in compression ratio to lower the bitrate of the
video. Instead, a suitable option for adaptive streaming is to scale down the
video temporally or spatially before encoding to maintain a desirable level of
perceptual quality, while the viewing resolution is constant. Most of the
existing studies to examine these scenarios are either limited to low
resolution videos or lack in provisioning of subjective assessment of quality.
We present here the results of our campaign of subjective quality assessment
experiments done on a range of spatial and temporal resolutions, up to VGA and
30 frames per second respectively, under a number of bitrate conditions. The
analysis shows, among other things, that keeping the spatial resolution is
perceptually preferred among the three parameters that have impact on the video
quality, even in the case with high temporal activity
A systematic literature review on the industrial use of software process simulation
No full textContext Software process simulation modelling (SPSM) captures the dynamic
behaviour and uncertainty in the software process. Existing literature has
conflicting claims about its practical usefulness: SPSM is useful and has an
industrial impact; SPSM is useful and has no industrial impact yet; SPSM is not
useful and has little potential for industry. Objective To assess the
conflicting standpoints on the usefulness of SPSM. Method A systematic
literature review was performed to identify, assess and aggregate empirical
evidence on the usefulness of SPSM. Results In the primary studies, to date,
the persistent trend is that of proof-of-concept applications of software
process simulation for various purposes (e.g. estimation, training, process
improvement, etc.). They score poorly on the stated quality criteria. Also only
a few studies report some initial evaluation of the simulation models for the
intended purposes. Conclusion There is a lack of conclusive evidence to
substantiate the claimed usefulness of SPSM for any of the intended purposes. A
few studies that report the cost of applying simulation do not support the
claim that it is an inexpensive method. Furthermore, there is a paramount need
for improvement in conducting and reporting simulation studies with an emphasis
on evaluation against the intended purpose
Methods for Objective and Subjective Video Quality Assessment and for Speech Enhancement
No full textThe overwhelming trend of the usage of multimedia services has raised the
consumers' awareness about quality. Both service providers and consumers are
interested in the delivered level of perceptual quality. The perceptual quality
of an original video signal can get degraded due to compression and due to its
transmission over a lossy network. Video quality assessment (VQA) has to be
performed in order to gauge the level of video quality. Generally, it can be
performed by following subjective methods, where a panel of humans judges the
quality of video, or by using objective methods, where a computational model
yields an estimate of the quality. Objective methods and specifically
No-Reference (NR) or Reduced-Reference (RR) methods are preferable because they
are practical for implementation in real-time scenarios.
This doctoral thesis begins with a review of existing approaches proposed in
the area of NR image and video quality assessment. In the review, recently
proposed methods of visual quality assessment are classified into three
categories. This is followed by the chapters related to the description of
studies on the development of NR and RR methods as well as on conducting
subjective experiments of VQA. In the case of NR methods, the required features
are extracted from the coded bitstream of a video, and in the case of RR
methods additional pixel-based information is used. Specifically, NR methods
are developed with the help of suitable techniques of regression using
artificial neural networks and least-squares support vector machines.
Subsequently, in a later study, linear regression techniques are used to
elaborate the interpretability of NR and RR models with respect to the
selection of perceptually significant features. The presented studies on
subjective experiments are performed using laboratory based and crowdsourcing
platforms. In the laboratory based experiments, the focus has been on using
standardized methods in order to generate datasets that can be used to validate
objective methods of VQA. The subjective experiments performed through
crowdsourcing relate to the investigation of non-standard methods in order to
determine perceptual preference of various adaptation scenarios in the context
of adaptive streaming of high-definition videos.
Lastly, the use of adaptive gain equalizer in the modulation frequency domain
for speech enhancement has been examined. To this end, two methods of
demodulating speech signals namely spectral center of gravity carrier
estimation and convex optimization have been studied
Requirements Engineering: Best Practice
No full textMany software solutions have failed because they did not meet stakeholder
needs. In response to this problem a massive amount of techniques were
de-veloped to elicit stakeholder needs, to analyze the implications of these
needs on the software, to specify proposed software products, and to check
acceptance of these proposals. However, many of these techniques did not become
industrial practice because they were not practicable or ineffective when used
in real-world projects. To obtain an overview of what common practice is and to
understand which techniques reflect best practice because they are particularly
effective, we have surveyed a large number of industry projects. Based on 419
valid answers, this chapter gives an overview of commonly used requirements
engineering techniques. It also shows which of the techniques, when used in a
software project, correlate with require-ments engineering success. The chapter
concludes with recommendations for software projects and future research to
improve requirements engineer-ing practice
In press: Prioritizing agile benefits and limitations in relation to practice usage
No full textIn recent years, there has been significant shift from rigid development (RD)
toward agile. However, it has also been spotted that agile methodologies are
hardly ever followed in their pure form. Hybrid processes as combinations of RD
and agile practices emerge. In addition, agile adoption has been reported to
result in both benefits and limitations. This exploratory study (a) identifies
development models based on RD and agile practice usage by practitioners; (b)
identifies agile practice adoption scenarios based on eliciting practice usage
over time; (c) prioritizes agile benefits and limitations in relation to (a)
and (b). Practitioners provided answers through a questionnaire. The
development models are determined using hierarchical cluster analysis. The use
of practices over time is captured through an interactive board with practices
and time indication sliders. This study uses the extended hierarchical voting
analysis framework to investigate benefit and limitation prioritization. Four
types of development models and six adoption scenarios have been identified.
Overall, 45 practitioners participated in the prioritization study. A common
benefit among all models and adoption patterns is knowledge and learning, while
high requirements on professional skills were perceived as the main limitation.
Furthermore, significant variances in terms of benefits and limitations have
been observed between models and adoption patterns. The most significant
internal benefit categories from adopting agile are knowledge and learning,
employee satisfaction, social skill development, and feedback and confidence.
Professional skill-specific demands, scalability, and lack of suitability for
specific product domains are the main limitations of agile practice usage.
Having a balanced agile process allows to achieve a high number of benefits.
With respect to adoption, a big bang transition from RD to agile leads to poor
quality in comparison with the alternatives
Infrastructure and technology challenges
No full textIn this deliverable, we report on our work on infrastructural and technological
barriers to Open Access and preservation of research data as identified by key
stakeholder groups.
Through a mix of qualitative, quantitative and document review methods, we
identified five key barriers to successfully implementing Open Access to
research data in Europe: data heterogeneity and issues of standardisation;
accessibility and discoverability issues; data preservation and curation; data
quality and assessability; and data security. We explore these issues in detail
and present existing good practice, and technical and infrastructural solutions
used to mitigate such barriers.
This work was conducted within the EU FP7 funded project RECODE, which focuses
on developing policy recommendations for Open Access to Research Data in
Europe. In particular, this work is coordinated by RECODE Work Package 2 (WP2),
Infrastructure and technology
Psychosocial work environment, stress factors and individual characteristics among nursing staff in psychiatric in-patient care
No full textA Software Framework for Prioritized Spectrum Access in Heterogeneous Cognitive Radio Networks
No full textToday, the radio spectrum is rarely fully utilized. This problem is valid in
more domains, e.g., time, frequency and geographical location. To provide an
efficient utilization of the radio spectrum, the Cognitive Radio Networks
(CRNs) have been advanced. The key idea is to open up the licensed spectrum to
unlicensed users, thus allowing them to use the so-called spectrum
opportunities as long as they do not harmfully interfere with licensed users.
An important focus is laid on the limitation of previously reported research
efforts, which is due to the limited consideration of the problem of
competition among unlicensed users for spectrum access in heterogeneous CRNs.
A software framework is introduced, which is called PRioritized Opportunistic
spectrum Access System (PROAS). In PROAS, the heterogeneity aspects of CRNs are
specifically expressed in terms of cross-layer design and various wireless
technologies. By considering factors like ease of implementation and efficiency
of control, PROAS provides priority scheduling based solutions to alleviate the
competition problem of unlicensed users in heterogenous CRNs. The advanced
solutions include theoretical models, numerical analysis and experimental
simulations for performance evaluation. By using PROAS, three particular CRN
models are studied, which are based on ad-hoc, mesh-network and
cellular-network technologies. The reported results show that PROAS has the
ability to bridge the gap between research results and the practical
implementation of CRNs
Development and Evaluation of OpenLabs and the VISIR Open Electronics and Radio Signal Laboratory for Education Purpose
No full textPart I and II of this thesis constitute a theoretical and practical approach on
how to open up a laboratory for remote access and enabling students to have
access to the equipment 24/7. Part I covers a more general solution for
enabling remote access to equipment; the suggested solution can be applied to
all types of instruments that can be controlled from a PC based system.
Part III and IV of this thesis present an encouragement to collaborate within
in the field of remote engineering to utilize the recourses more efficiently.
The idea is that universities around the world can share their experiments in a
grid laboratory; every university contributes with a small part, but gets
access to a wide range of experiments in this grid.
Part V of this thesis concerns the modelling and simulation of the remote
electronics laboratory with the purpose of estimating the maximum number of
simultaneous users without losing the experience of working with a real
instrument. The results indicate that one single remote electronics laboratory
can handle up to 120 users simultaneously and with 120 users the delay for each
user is approximately 2 seconds
What Type of Knowledge Rules Where? Legally regulated participation in a large-scale mobile infrastructure planning in Sweden
No full textI investigate the field of tension between the national and the local level in
spatial planning from a decision-making perspective. In doing so, I analyse the
legal regulation for a large-scale 3G mobile infrastructure development in
Sweden with a focus on how participation is expressed both in terms of the ‘law
in books’ as well as empirically, ‘in action’. Theoretically, a model of
decision making is elaborated, based on two axes: one concerning the decision
level on a central or national to local scale, and one concerning what type of
knowledge is regarded as the most legitimate in terms of a calculating approach
versus a communicative approach. These two issues or approaches to decision
making—who decides and based on what knowledge—are of direct importance for
understanding the frameworks as well as the practical outcomes of public
participation. The case of 3G in Sweden demonstrates how different types of
knowledge are perceived as legitimate at different levels in the planning
system. For example, appeals against building permits rarely change the outcome
of permits issued, and appeals based on fear of electromagnetic radiation are
always rejected. The juridification of a given mast conflict meant a
development from a deliberative approach, where any concern is heard, to a
calculating and expert-based one, where the general stance on a particular
topic (such as whether or not the electromagnetic radiation from mobile masts
is hazardous) is applied. This means that what knowledge is legitimate depends
on where in the permit process it is presented