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Worldviews, Research Methods, and their Relationship to Validity in Empirical Software Engineering Research
No full textAbstract—Background - Validity threats should be considered and consistently
reported to judge the value of an empirical software engineering research
study. The relevance of specific threats for a particular research study
depends on the worldview or philosophical worldview of the researchers of the
study. Problem/Gap - In software engineering, different categorizations exist,
which leads to inconsistent reporting and consideration of threats.
Contribution - In this paper, we relate different worldviews to software
engineering research methods, identify generic categories for validity threats,
and provide a categorization of validity threats with respect to their
relevance for different world views. Thereafter, we provide a checklist aiding
researchers in identifying relevant threats. Method - Different threat
categorizations and threats have been identified in literature, and are
reflected on in relation to software engineering research. Results - Software
engineering is dominated by the pragmatist worldviews, and therefore use
multiple methods in research. Maxwell’s categorization of validity threats has
been chosen as very suitable for reporting validity threats in software
engineering research. Conclusion - We recommend to follow a checklist approach,
and reporting first the philosophical worldview of the researcher when doing
the research, the research methods and all threats relevant, including open,
reduced, and mitigated threats
The Capability of Time- And Frequency-domain Algorithms for Bistatic SAR Processing
No full textThe paper presents a study of the capability of time- And frequency-domain
algorithms for bistatic SAR processing. Two typical algorithms, Bistatic Fast
Backprojection (BiFBP) and Bistatic Range Doppler (BiRDA), which are both
available for general bistatic geometry, are selected as the examples of time-
And frequency-domain algorithms in this study. Their capability is evaluated
based on some criteria such as processing time required by the algorithms to
reconstruct SAR images from bistatic SAR data and the quality assessments of
those SAR images
Offshore Insourcing in Software Development: Structuring the Decision-Making Process
No full textA variety of new forms of business are enabled through globalization and
practiced by software organizations today. While companies go global to reduce
their development costs, access a larger pool of resources and explore new
markets, it is often assumed that the level of delivered services shall remain
the same after implementing the sourcing decisions. In contrast, critical
studies identified that global software development is associated with unique
challenges, and a lot of global projects fail to mitigate the implications of a
particular global setting. In this paper we explore offshore insourcing
decisions on the basis of empirical research literature and an empirical field
study conducted at Ericsson. By analyzing decisions in two different cases we
found that each offshore insourcing decision consisted of deciding what, where,
when, how and why to insource. Related empirical research and field
observations suggest that not all combinations are successful and alignment
between different decision points has thus a prominent role. To address these
concerns we built an empirically-based insourcing decision structure, which
outlines a logical path through the decision options and helps selecting an
offshore insourcing strategy that targets creation of the necessary alignment.
The key element of the proposed approach is a structured and well-defined
decision-making process, which is intended to support managers in their
decision-making. The usefulness of the proposed approach is evaluated in an
additional empirical case of a new offshore insourcing decision
Unlocking Potentials of Innovation Systems in Low Resource Settings
No full textThis study examined the dynamics, challenges and opportunities of developing
innovation systems in low resource settings with a particular focus on Uganda.
It applied perspectives of technoscience and concepts of innovation systems,
triple helix as university-industry-government relationships, mode 2 knowledge
production and situated knowledges in understanding the context, identifying
key policy issues and suggesting ways to address them. A mixed methodology
combining both quantitative and qualitative methods was used in the study. It
involved review of key policy documents, key informant interviews, focus group
discussions and meetings with scientists, business leaders in the target
organizations and firms, community members as well as observations of
production processes in firms. Findings underscore the need for greater
interaction and learning among actors in the emerging innovation systems in
Uganda and eastern Africa. An opportunity for this to happen may be the growing
number of entrepreneurial initiatives at the university and some public
research organizations in the country. These entrepreneurial initiatives are
driven by scientists, who are enthusiastic about moving their research results
and innovations to market. This makes it plausible, in low resource settings
like in Uganda, to promote the university working closely with public research
organizations and firms as a locus for research and innovation. However,
enabling conditions, which foster interaction and learning among actors, should
be put in place. First, there is need to formulate specific policies and
strategies with clear goals and incentives to promote growth of particular
innovation systems. Second, a clear national policy for financing research and
innovation is needed, which involves on the one part core funding to
universities and research organizations, and on the other, competitive grants
for research and innovation. Third, business incubation services should be
established and/or supported as places where entrepreneurial scientists and
other persons develop and test their business ideas and models. Fourth, there
is need for institutional reforms to make administrative processes less
bureaucratic, more costeffective and efficient. These reforms are necessary for
example in processes involving procurement and financial management, research
project approvals (for ethics and safety), technology assessments, contracting
and licensing and other registration services. The findings and conclusions
from this study demonstrate that technoscientific perspectives and innovation
systems approaches can be adapted and used as a framework for identifying and
explaining conditions that promote or hamper innovation in low resource
settings as well as policy options to address them
Delay and Throughput Analysis for Opportunistic Decode-and-Forward Relay Networks
No full textIn this paper, we develop a queueing analysis for opportunistic
decode-and-forward (DF) relay networks. It is assumed that the networks undergo
Nakagami-m fading and that the external arrival process follows a Poisson
distribution. By selecting the best relay according to the opportunistic
relaying scheme, the source first transmits its signal to the best relay which
then attempts to decode the reception and forwards the output to the
destination. It is assumed that each relay operates in full-duplex mode, i.e.,
it can receive and transmit signals simultaneously. The communication process
throughout the network can be modeled as a queueing network which is structured
from sub-systems of M/G/1 and G/G/1 queueing stations. We invoke the
approximate analysis, so-called method of decomposition, to analyze the
performance behavior of the considered relay network. The whole queueing
network is broken into separate queues which are then investigated
individually. Based on this approach, the end-to-end packet transmission time
and throughput of the considered relay network are quantified in comparison
with the networks with partial relay selection (PRS)
Social media for user innovation in Living Labs: a framework to support user recruitment and commitment
No full textSocial media are becoming an increasingly relevant channel for user
involvement. However, their uptake in Living Labs environments, as a means to
engage users in innovation processes, is still limited. The aim of this paper
is to explore challenges and opportunities related to the usage of social media
for user involvement in co-creative processes, The findings presented emerge
both from the available literature and case studies, and emphasise four
different dimensions influencing user engagement: content, community, platform
and innovation process. Based on these dimensions, the authors propose a basic
framework, intended as the point of departure for taking the next step toward
the construction and verification of theoretical constructs that can help
inform and guide future innovation projects
Performance Analysis of Cognitive Radio Networks with Interference Constraints
No full textTo support the rapidly increasing number of mobile users and mobile multimedia
services, and the related demands for bandwidth, wireless communication
technology is facing a potentially scarcity of radio spectrum resources.
However, spectrum measurement campaigns have shown that the shortage of radio
spectrum is due to inefficient usage and inflexible spectrum allocation
policies. Thus, to be able to meet the requirements of bandwidth and spectrum
utilization, spectrum underlay access, one of the techniques in cognitive radio
networks (CRNs), has been proposed as a frontier solution to deal with this
problem. In a spectrum underlay network, the secondary user (SU) is allowed to
simultaneously access the licensed frequency band of the primary user (PU) as
long as the interference caused by the SU to the PU is kept below a predefined
threshold. By doing so, the spectrum utilization can be improved significantly.
Moreover, the spectrum underlay network is not only considered as the least
sophisticated in implementation, but also can operate in dense areas where the
number of temporal spectrum holes is small. Inspired by the above discussion,
this thesis provides a performance analysis of spectrum underlay networks which
are subject to interference constraints.
The thesis is divided into an introduction part and five parts based on
peer-reviewed international research publications. The introduction part
provides the reader with an overview and background on CRNs. The first part
investigates the performance of secondary networks in terms of outage
probability and ergodic capacity subject to the joint outage constraint of the
PU and the peak transmit power constraint of the SU. The second part evaluates
the performance of CRNs with a buffered relay. Subject to the timeout
probability constraint of the PU and the peak transmit power constraint of the
SU, system performance in terms of end-to-end throughput, end-to-end
transmission time, and stable transmission condition for the relay buffer is
studied. The third part analyzes a cognitive cooperative radio network under
the peak interference power constraint of multiple PUs with best relay
selection. The obtained results readily reveal insights into the impact of the
number of PUs, channel mean powers of the communication and interference links
on the system performance. The fourth part studies the delay performance of
CRNs under the peak interference power constraint of multiple PUs for
point-to-point and point-to-multipoint communications. A closedform expression
for outage probability and an analytical expression for the average waiting
time of packets are obtained for point-to-point communications. Moreover, the
outage probability and successful transmission probability for packets in
point-to-multipoint communications are presented. Finally, the fifth part
presents work on the performance analysis of a spectrum underlay network for a
general fading channel. A lower bound on the packet timeout probability and the
average number of transmissions per packet are obtained for the secondary
network
Integrating Moldflow and Abaqus in the Package Simulation Workflow
No full textTetra Pak has used numerical simulation tools for plastic injection molding
(Moldflow) and structural analysis (Abaqus/Implicit and Abaqus/Explicit) for
many years. Today these two simulation tools are used independently of each
other without any coupling. How these two disciplines can be combined to better
predict the mechanical response of a polymer component is presented in this
work. The manufacturing process, in this case injection molding, creates the
mechanical properties of the produced polymer part. Process settings, material
selection and molding tool geometry affect the polymer flow, material
orientation and rate of crystallinity. A method to build a layered finite
element model in Abaqus using results from Moldflow simulations regarding
crystallinity growth and molecular orientation is proposed. Relatively simple
material models were utilized and assigned for each individual material layer
through the thickness in the polymer part. These constitutive models were
derived phenomenologically from experimental test results and could adequately
capture both the microscopic and the macroscopic behavior in a more realistic
way. The numerical results showed a good agreement with the experimental
results, both regarding visual appearance and force/displacement response
Deformation and Damage Mechanisms in Thin Ductile Polymer Films
No full textThe mechanical material behavior of highly extensible or ductile polymer films
used in the packaging industry has been studied in this work. The polymer
material, consisting of different variants of polyethylene grades, is used as
several components in the packaging material structure at Tetra Pak®.
Experimental tensile tests were used to quantify the mechanical behavior and to
be able to calibrate numerical constitutive material models. The studied
polymer materials were able to withstand large deformations before breaking,
involving both necking in the width and thickness direction of the specimen.
During deformation re-orientation of polymer chains and substantial
strain-hardening were also occurring. The latter effect was accounted for in
the presented material modeling approach. The numerical simulations were solved
in the general finite element software Abaqus version 6.13. In this work a
continuum damage modeling (CDM) approach was used. CDM which are attractive in
macro scale applications, thus solving our engineering problems, was chosen in
this study due to the computational efficiency. A damage model consisting of
two functionalities; initiation of damage and evolution of damage was suitable
for modeling the ductile fracture behavior. During the numerical analysis it
has been assumed that the polymer materials are isotropic, homogenous through
the thickness, independent of strain rate and independent of temperature to
ease the material parameters identification
Visualization of Defect Inflow and Resolution Cycles: Before, During and After Transfer
No full textThe link between maintenance and product quality, as well as the high cost of
software maintenance, highlights the importance of efficient maintenance
processes. Sustaining maintenance work efficiency in a global software
development setting that involves a transfer is a challenging endeavor. Studies
report on the negative effect of transfers on efficiency. However, empirical
evidence on the magnitude of the change in efficiency is scarce. In this study
we used a lean indicator to visualize variances in defect resolution cycles for
two large products during evolution, before, during and after a transfer. Focus
group meetings were also held for each product. Study results show that during
and immediately after the transfer the defect inflow is higher, bottlenecks are
more visible, and defect resolution cycles are longer, as compared to before
the transfer. Furthermore we highlight the factors that influenced the change
in defect resolution cycles before, during, and after the transfer