A No-Reference Bitstream-based Perceptual Model for Video Quality Estimation of Videos Affected by Coding Artifacts and Packet Losses

In this work, we propose a No-Reference (NR) bitstream-based model for predicting the quality of H.264/AVC video sequences, aeffected by both compression artifacts and transmission impairments. The concept of the article is based on a feature extraction procedure, where a large number of features are calculated from the impaired bitstream. Many of the features are mostly proposed in this work, while the specificc set of the features as a whole is applied for the first time for making NR video quality predictions. All feature observations are taken as input to the Least Absolute Shrinkage and Selection Operator (LASSO) regression method. LASSO indicates the most important features, and using only them, it is able to estimate the Mean Opinion Score (MOS) with high accuracy. Indicatively, we point out that only 13 features are able to produce a Pearson Correlation Coefficient of 0:92 with the MOS. Interestingly, the performance statistics we computed in order to assess our method for predicting the Structural Similarity Index and the Video Quality Metric are equally good. Thus, the obtained experimental results verifi ed the suitability of the features selected by LASSO as well as the ability of LASSO in making accurate predictions through sparse modeling

The Contextual Nature of Innovation - An Empirical Investigation of Three Software Intensive Products

Context: New products create significant opportunities for differentiation and competitive advantage. To increase the chances of new product success, a universal set of critical activities and determinants have been recommended. Some researchers believe, however, that these factors are not universal, but are contextual. Objective: This paper reports innovation processes followed to develop three software intensive products for understanding how and why innovation practice is dependent on innovation context. Method: This paper reports innovation processes and practices with an in-depth multi-case study of three software product innovations from Ericsson, IBM, and Rorotika. It describes the actual innovation processes followed in the three cases and discusses the observed innovation practice and relates it to state-of-the-art. Results: The cases point to a set of contextual factors that influence the choice of innovation activities and determinants for developing successful product innovations. The cases provide evidence that innovation practice cannot be standardized, but is contextual in nature. Conclusion: The rich description of the interaction between context and innovation practice enables future investigations into contextual elements that influence innovation practice, and calls for the creation of frameworks enabling activity and determinant selection for a given context – since one size does not fit all

In press: A Cross-Layer Optimized Scheme and Its Application in Mobile Multimedia Networks With QoS Provision

To cope with the rapid growth of multimedia applications that requires dynamic levels of quality of service (QoS), cross-layer (CL) design, where multiple protocol layers are jointly combined, has been considered to provide diverse QoS provisions for mobile multimedia networks. However, there is a lack of a general mathematical framework to model such CL scheme in wireless networks with different types of multimedia classes. In this paper, to overcome this shortcoming, we therefore propose a novel CL design for integrated real-time/non-real-time traffic with strict preemptive priority via a finite-state Markov chain. The main strategy of the CL scheme is to design a Markov model by explicitly including adaptive modulation and coding at the physical layer, queuing at the data link layer, and the bursty nature of multimedia traffic classes at the application layer. Utilizing this Markov model, several important performance metrics in terms of packet loss rate, delay, and throughput are examined. In addition, our proposed framework is exploited in various multimedia applications, for example, the end-to-end real-time video streaming and CL optimization, which require the priority-based QoS adaptation for different applications. More importantly, the CL framework reveals important guidelines as to optimize the network performance

Feasibility of using existing open access networks to support the harmonization of open access

In this report we identify and assess different options for bringing together and mobilizing relevant stakeholders in the open access arena. This builds on previous work done in the RECODE project about the open access stakeholder ecosystem, the barriers and the enablers for open access to research data as well as on the RECODE overarching policy recommendations set out in the RECODE work package 5. We have identified a sample of existing networks and organizations to determine whether they are able to meet stakeholder needs and mobilization objectives for open access, data preservation, dissemination and use, and what these organizations can or must do in order to better mobilize stakeholders in order to meet the policy recommendations. We have identified not only examples of good practice but also the barriers not addressed by any currently available structures or organizations. While there are many forces striving to make data sharing common practice, there is still a lack of an overarching, international initiative to implement necessary requirements for making data sharing a truly international community asset. Within the European community the prerequisites and the ambitions are very different among the member states. Even amongst those countries where open access has long been on the agenda, there remain issues and barriers to be addressed. For example, training is needed in most of the stakeholder groups; investment in infrastructure building and funding is required in most institutions dealing with open access to research data; much work remains to be done to convince researchers that sharing data is a good idea. These are just a few of the obstacles that still need attention despite good, on-going efforts by individuals, organizations and states

VLQoE: Video QoE instrumentation on the smartphone

The usage of network-demanding applications is growing rapidly such as video streaming on mobile terminals. However, network and/or service providers might not guarantee the perceived quality for video streaming that demands high packet transmission rate. In order to satisfy the user expectations and to minimize user churn, it is important for network operators to infer the end-user perceived quality in video streaming. Today, the most reliable method to obtain end-user perceived quality is through subjective tests, and the preferred location is the user interface as it is the closest point of application to the end-user. The end-user perceived quality on video streaming is highly influenced by occasional freezes; technically the extraordinary time gaps between two consecutive pictures that are displayed to the user, i.e., high inter-picture time. In this paper, we present a QoE instrumentation for video streaming, VLQoE. We added functionality to the VLC player to record a set of metrics from the user interface, application-level, network-level, and from the available sensors of the device. To the best of our knowledge, VLQoE is the first tool of its kind that can be used in user experiments for video streaming. By using the tool, we present a two state model based on the inter-picture time, for the HTTP- and RTSP-based video streaming via 3.5G. Next, we studied the influence of inter-picture time on the user perceived quality through out a user study. We investigated the minimum user perceived inter-picture time, and the user response time

Operationalization of lean thinking through value stream mapping with simulation and FLOW

Background: The continued success of Lean thinking beyond manufacturing has led to an increasing interest to utilize it in software engineering (SE). Value Stream Mapping (VSM) had a pivotal role in the operationalization of Lean thinking. However, this has not been recognized in SE adaptations of Lean. Furthermore, there are two main shortcomings in existing adaptations of VSM for an SE context. First, the assessments for the potential of the proposed improvements are based on idealistic assertions. Second, the current VSM notation and methodology are unable to capture the myriad of significant information flows, which in software development go beyond just the schedule information about the flow of a software artifact through a process. Objective: This thesis seeks to assess Software Process Simulation Modeling (SPSM) as a solution to the first shortcoming of VSM. In this regard, guidelines to perform simulation-based studies in industry are consolidated, and the usefulness of VSM supported with SPSM is evaluated. To overcome the second shortcoming of VSM, a suitable approach for capturing rich information flows in software development is identified and its usefulness to support VSM is evaluated. Overall, an attempt is made to supplement existing guidelines for conducting VSM to overcome its known shortcomings and support adoption of Lean thinking in SE. The usefulness and scalability of these proposals is evaluated in an industrial setting. Method: Three literature reviews, one systematic literature review, four industrial case studies, and a case study in an academic context were conducted as part of this research. Results: Little evidence to substantiate the claims of the usefulness of SPSM was found. Hence, prior to combining it with VSM, we consolidated the guidelines to conduct an SPSM based study and evaluated the use of SPSM in academic and industrial contexts. In education, it was found to be a useful complement to other teaching methods, and in the industry, it triggered useful discussions and was used to challenge practitioners’ perceptions about the impact of existing challenges and proposed improvements. The combination of VSM with FLOW (a method and notation to capture information flows, since existing VSM adaptions for SE are insufficient for this purpose) was successful in identifying challenges and improvements related to information needs in the process. Both proposals to support VSM with simulation and FLOW led to identification of waste and improvements (which would not have been possible with conventional VSM), generated more insightful discussions and resulted in more realistic improvements. Conclusion: This thesis characterizes the context and shows how SPSM was beneficial both in the industrial and academic context. FLOW was found to be a scalable, lightweight supplement to strengthen the information flow analysis in VSM. Through successful industrial application and uptake, this thesis provides evidence of the usefulness of the proposed improvements to the VSM activities

Realistic Package Opening Simulations : An Experimental Mechanics and Physics Based Approach

A finite element modeling strategy targeting package opening simulations is the final goal with this work. The developed simulation model will be used to proactively predict the opening compatibility early in the development process of a new opening device and/or a new packaging material. To be able to create such a model, the focus is to develop a combined and integrated physical/virtual test procedure for mechanical characterization and calibration of thin packaging materials. Furthermore, the governing mechanical properties of the materials involved in the opening performance needs to be identified and quantified with experiments. Different experimental techniques complemented with video recording equipment were refined and utilized during the course of work. An automatic or semi-automatic material model parameter identification process involving video capturing of the deformation process and inverse modeling is proposed for the different packaging material layers. Both an accurate continuum model and a damage material model, used in the simulation model, were translated and extracted from the experimental test results. The results presented show that it is possible to select constitutive material models in conjunction with continuum material damage models, adequately predicting the mechanical behavior of intended failure in thin laminated packaging materials. A thorough material mechanics understanding of individual material layers evolution of microstructure and the micro mechanisms involved in the deformation process is essential for appropriate selection of numerical material models. Finally, with a slight modification of already available techniques and functionalities in the commercial finite element software AbaqusTM it was possible to build the suitable simulation model. To build a realistic simulation model an accurate description of the geometrical features is important. Therefore, advancements within the experimental visualization techniques utilizing a combination of video recording, photoelasticity and Scanning Electron Microscopy (SEM) of the micro structure have enabled extraction of geometries and additional information from ordinary standard experimental tests. Finally, a comparison of the experimental opening and the virtual opening, showed a good correlation with the developed finite element modeling technique. The advantage with the developed modeling approach is that it is possible to modify the material composition of the laminate. Individual material layers can be altered and the mechanical properties, thickness or geometrical shape can be changed. Furthermore, the model is flexible and a new opening device i.e. geometry and load case can easily be adopted in the simulation model. Therefore, this type of simulation model is a useful tool and can be used for decision support early in the concept selection of development projects

On the Performance of Underlay Cognitive Radio Networks with Interference Constraints and Relaying

Efficiently allocating the scarce and expensive radio resources is a key challenge for advanced radio communication systems. To this end, cognitive radio (CR) has emerged as a promising solution which can offer considerable improvements in spectrum utilization. Furthermore, cooperative communication is a concept proposed to obtain spatial diversity gains through relays without requiring multiple antennas. To benefit from both CR and cooperative communications, a combination of CR networks (CRNs) with cooperative relaying referred to as cognitive cooperative relay networks (CCRNs) has recently been proposed. CCRNs can better utilize the radio spectrum by allowing the secondary users (SUs) to opportunistically access spectrum, share spectrum with primary users (PUs), and provide performance gains offered by cooperative relaying. In this thesis, a performance analysis of underlay CRNs and CCRNs in different fading channels is provided based on analytical expressions, numerical results, and simulations. To allocate power in the CCRNs, power allocation policies are proposed which consider the peak transmit power limit of the SUs and the outage probability constraint of the primary network. Thus, the impact of multiuser diversity, peak transmit power, fading parameters, and modulation schemes on the performance of the CRNs and CCRNs can be analyzed. The thesis is divided into an introduction and five research parts based on peer-reviewed conference papers and journal articles. The introduction provides fundamental background on spectrum sharing systems, fading channels, and performance metrics. In the first part, a basic underlay CRN is analyzed where the outage probability and the ergodic capacity of the network over general fading channels is derived. In the second part, the outage probability and the ergodic capacity of an underlay CRN are assessed capturing the effect of multiuser diversity on the network subject to Nakagami-m fading. Considering the presence of a PU transmitter (PU-Tx), a power allocation policy is derived and utilized for CRN performance analysis under Rayleigh fading. In the third part, the impact of multiple PU-Txs and multiple PU receivers (PU-Rxs) on the outage probability of an underlay CCRN is studied. The outage constraint at the PU-Rx and the peak transmit power constraint of the SUs are taken into account to derive the power allocation policies for the SUs. In the fourth part, analytical expressions for the outage probability and symbol error probability for CCRNs are derived where signal combining schemes at the SU receiver (SU-Rx) are compared. Finally, the fifth part applies a sleep/wake-up strategy and the min(N; T) policy to an underlay CRN. The SUs of the network operate as wireless sensor nodes under Nakagami-m fading. A power consumption function of the CRN is derived. Further, the impact of M/G/1 queue and fading channel parameters on the power consumption is assessed

Heterogeneous Systems Testing Techniques: An Exploratory Survey

Heterogeneous systems comprising sets of inherent subsystems are challenging to integrate. In particular, testing for interoperability and conformance is a challenge. Furthermore, the complexities of such systems amplify traditional testing challenges. We explore (1) which techniques are frequently discussed in literature in context of heterogeneous system testing that practitioners use to test their heterogeneous systems; (2) the perception of the practitioners on the usefulness of the techniques with respect to a defined set of outcome variables. For that, we conducted an exploratory survey. A total of 27 complete survey answers have been received. Search-based testing has been used by 14 out of 27 respondents, indicating the practical relevance of the approach for testing heterogeneous systems, which itself is relatively new and has only recently been studied extensively. The most frequently used technique is exploratory manual testing, followed by combinatorial testing. With respect to the perceived performance of the testing techniques, the practitioners were undecided regarding many of the studied variables. Manual exploratory testing received very positive ratings across outcome variables