Blekinge Institute of Technology
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Agent-based simulation of freight transport between geographical zones
No full textWe present TAPAS-Z, which is an agent-based freight transport analysis model
for simulation of decision-making and transport activities. TAPAS-Z is a
further development of a simulation model called TAPAS, and it has improved
support for simulation of transport in large geographical regions. It is based
on the principles that shipments are simulated for chosen supplier-consumer
relations in a geographic region, and that the geographic locations of
suppliers and consumers are randomly varied for each shipment. In TAPAS-Z, one
supplier represents all real-world suppliers in a geographic zone, and one
consumer represents all real-world consumers in a zone. In that way, TAPAS-Z is
able to capture some of the diversity in freight transport that is caused by
the varying geographic locations of senders and receivers, and which is
important when assessing the impact of transport policy and infrastructural
measures
Multi-Strategy Based Train Re-Scheduling During Railway Traffic Disturbances
No full textDisruptions and delays in railway traffic networks due to different types of
disturbances is a frequent problem in many countries. When disruptions occur,
the train traffic dispatchers may need to re-schedule the traffic and this is
often a very demanding and complicated task. To support the train traffic
dispatchers, we propose to use a parallelized multi-strategy based greedy
algorithm. This paper presents three different parallelization approaches: (i)
Single Strategy with a Partitioned List (i.e. the parallel processes originate
from different starting points), (ii) Multiple Strategies with a
Non-Partitioned List, and (iii) Multiple Strategies with a Partitioned List. We
present an evaluation for a busy part of the Swedish railway network based on
performance metrics such as the sum of all train delays at their final
destinations and the number of delayed trains. The results show that
parallelization helps to improve the solution quality. The parallel approach
(iii) that combines all re-scheduling strategies with a partitioned list
performs best among the three parallel approaches when minimizing the total
final delay. The main conclusion is that the multi-strategy based parallel
approach significantly improves the solution for 11 out of 20 disturbance
scenarios, as compared to the sequential re-scheduling algorithm. The approach
also provides an increased stability since it always delivers a feasible
solution in short time
Decision Support Approach for Modeling Sustainability Consequences in an Aerospace Value Chain
No full textNext generation jet engine technologies are typically driven by performance,
value and environmental challenges, and appropriate technologies are developed
in international research programs. One on-going engine component technology
project at an aerospace component manufacturer aims to develop an engine with
less fuel consumption. A likely consequence is higher pressure in the core
engine, which leads to higher temperature. One way to handle the higher
temperature is using a more advanced Ti-alloy for the product component, which
will render a different sustainability profile. One weakness in current
decision situations is the inability to clarify and understand the “value” and
“sustainability” implications compared to e.g. performance features of
concepts. Both “value” and “sustainability” include a rich set of features
important for successful introduction of new products and product-service
solutions to the market. The purpose with this research is to provide decision
support for companies in early development phases for assessment of value and
sustainability consequences over product-service system lifecycles.
A workshop was held with the aerospace component manufacturer and a value chain
partner focusing on material handling, to: i) get a better understanding of
activities, flows and ownership related to the studied materials at the two
companies, ii) to understand the companies’ perspective at new suggested
scenarios with regard to these materials, and iii) define relevant scenarios to
look into more in depth from asustainability and value perspective. Three
different scenarios were developed with differences in ownership,
responsibilities and value streams. It is therefore essential to be able to
quickly assess and optimize consequences of such alternative scenarios.
Based on the workshop experiences and scenarios, a modeling and simulation
approach to assess sustainability and value consequences for the scenarios is
proposed. The sustainability consequences are based on a sustainability life
cycle assessment and a risk assessment. Key features of the proposed tool
include: consideration of the time dimension, societal sustainability
consequences, risk assessment, company value assessment, and cost/revenue
perspectives
Trouser tear tests of two thin polymer films
No full textTrouser tear testing has been concerned in this research work. A polypropylene
film and a low density polyethylene film used in the packaging industry are
considered. The experimental trouser tear tests showed different results for
both materials when they were subjected to load in different material
directions.
Therefore the hypothesis was verified, that the in-plane material
orientation/alignment induced during manufacturing, hence creating anisotropic
in-plane mechanical properties, also affects the tearing behavior. A
brittle-like failure was shown in the polypropylene film while the low density
polyethylene presented a highly ductile behavior. The two polymer films can be
classified as one low-extensible and one high-extensible material according to
the test method utilized. Material parameters in the principal material
directions i.e. manufacturing direction and cross direction were extracted from
the experimental tests for further numerical studies. Scanning electron
microscope was used for micromechanical and fractographical analysis of the
crack tip and crack surfaces created during the tests. The methods discussed
will help classify different groups of materials and can be used as a
predictive tool for the crack initiation and crack propagation path in
packaging material, especially thin polymer films
Conservation laws and exact solutions for nonlinear diffusion in anisotropic media
No full textConservation laws and exact solutions of nonlinear differential equations
describing diffusion phenomena in anisotropic media with external sources are
constructed. The construction is based on the method of nonlinear
self-adjointness. Numerous exact solutions are obtained by using the recent
method of conservation laws. These solutions are different from group invariant
solutions and can be useful for investigating diffusion
phenomena in complex media, e.g. in oil industry
Towards Guidelines for Conducting Software Process Simulation in Industry
No full textBackground: Since the 1950s explicit software process models have been used for
planning, executing and controlling software development activities. To
overcome the limitation of static models at capturing the inherent dynamism in
software development, Software Process Simulation Modelling (SPSM) was
introduced in the late 1970s. SPSM has been used to address various challenges,
e.g. estimation, planning and process assessment. The simulation models
developed over the years have varied in their scope, purpose, approach and the
application domain. However, there is a need to aggregate the evidence
regarding the usefulness of SPSM for achieving its intended purposes.
Objective: This thesis aims to facilitate adoption of SPSM in industrial
practice by exploring two directions. Firstly it aims to establish the
usefulness of SPSM for its intended purposes, e.g. for planning, training and
as an alternative to study the real world software (industrial and open source)
development. Secondly to define and evaluate a process for conducting SPSM
studies in industry.
Method: Two systematic literature reviews (SLR), a literature review, a case
study and an action research study were conducted. A literature review of
existing SLRs was done to identify the strategies for selecting studies. The
resulting process for study selection was utilized in an SLR to capture and
aggregate evidence regarding the usefulness of SPSM. Another SLR was used to
identify existing process descriptions of how to conduct an SPSM study. The
consolidated process and associated guidelines identified in this review were
used in an action research study to develop a simulation model of the testing
process in a large telecommunication vendor. The action research was preceded
by a case study to understand the testing process at the company.
Results: A study selection process based on the strategies identified from
literature was proposed. It was found to systemize selection and to support
inclusiveness with reasonable additional effort in an SLR of the SPSM
literature. The SPSM studies identified in literature scored poorly on the
rigor and relevance criteria and lacked evaluation of SPSM for the intended
purposes. Lastly, based on literature, a six-step process to conduct an SPSM
study was used to develop a System Dynamics model of the testing process for
training purposes in the company.
Conclusion: The findings identify two potential directions for facilitating
SPSM adoption. First, by learning from other disciplines having done simulation
for a longer time. It was evident how similar the consolidated process for
conducting an SPSM study was to the process used in simulation in general.
Second the existing work on SPSM can at best be classified as strong
``proof-of-concept’’ that SPSM can be useful in the real world software
development. Thus, there is a need to evaluate and report the usefulness of
SPSM for the intended purposes with scientific rigor
Towards a Prediction Model for People Movements in Urban Areas
No full textThe aim of this work is to develop a new type of service for predicting and
communicating urban activity. This service provides short-term predictions
(hours to days), which can be used as a basis for different types of resource
allocation and planning, e.g. concerning public transport, personnel, or
marketing. The core of the service consists of a forecasting engine that based
on a prediction model processes data on different levels of detail and from
various providers. This paper explores the requirements and features of the
forecast engine. We conclude that agent-based modeling seems as the most
promising approach to meet these requirements. Finally, some examples of
potential applications are described along with analyses of scientific and
engineering issues that need to be addressed
Monitoring Infrastructure Affordances
No full textComputing has made its way into most of our lives as a key processor of vast
quantities of information. This has happened directly in terms of gadgets and
devices that assists us in everyday life, but also indirectly, through the
critical infrastructures that enables these devices to function. A key issue
with critical infrastructures such as transportation, communication,
power-grids and finance, is increasingly
circular interdependencies. Because of this issue, a disruption in either one
can cascade and have a global effect on the others. To manage these
complexities, we are depending on a number of monitoring systems that allow
operators and other stakeholders to, within their respective expert domains,
discover disruptions as early as possible and then take appropriate actions.
These monitoring systems are not without challenges of their own. In addition
to having evolved organically alongside their respective infrastructures, there
is a considerable legacy to account for, with both hardware and software
components spanning decades of computing history.
This puts heavy restrictions on the kinds of interventions that can be
performed safely, implying that these systems are ill fit for handling the
software and software security landscapes of today, where updates and
adjustments need to be applied on a daily basis in order to stand a fighting
chance.
The work presented herein address some of the major challenges in securing
these monitoring systems against current and future threats posed by
antagonistic actors, dormant software defects and changes imposed by
technological advances and academic discoveries. This is approached on several
fronts in parallel: by embedding resilience in order to allow for controlled
experimentation and evaluation of new protection mechanisms in incrementally
sensitive settings; by developing laboratory facilities for resilient smart
power-grids; and by developing tools and training scenarios for operators of
adaptive and reconfigurable monitoring systems
Vetenskapligt skrivande - filosofi, psykologi och pedagogik
No full textDet här bidragets ”nyttovärde” består av en argumentation mot en ofta
överdriven och obefogad tilltro till den vetenskapliga textens möjligheter. Man
kan definiera en text som ett erbjudande om tolkning av sändarsens avsikt,
situation och känslor. En skriftlig diskurs å andra sidan uppstår när utbyte av
idéer och erfarenheter kommer till stånd mellan parterna. Textdiskurser
innehåller instrumentella och sociala dimensioner som tillsammans överför
parternas mål och avsikter. Vid ansökningar om forskningsanslag kommunicerar vi
med vetenskapligt språk. Med dialogism som mål finns det förutsättningar för
interaktivt utbyte av information, förslag och idéer mellan sökande och
myndighter. Med andra förutsättningar skulle de senare kunna erbjuda
informations- och idéstöd, diskustera ansökningstextens utformning, ange
innehållskriterier, specificera omfattning, föreslå referenser m.
Discharge planning: Narrated by nursing staff in primary healthcare and their concerns about using video conferencing in the planning session – An interview study
No full textBackground/Objective: This paper sets out to describe experience-based
reflections on discharge planning as narrated by nursing staff in primary
healthcare, along with their concerns about how the introduction of video
conferencing might influence the discharge planning situation.
Methods: Interviews were conducted with nursing staff working at a primary
healthcare centre in South East Sweden. Each interview took place was conducted
on a one-to-one basis in dialogue form, using open questions and supported by
an interview guide. It was then analysed using a phenomenological hermeneutic
method. Participants were eligible for the study if they had given their
informed consent and if they worked with discharge planning and home-based
healthcare provision. In total, 10 of the 30 persons working at the primary
healthcare centre participated in the study.
Results: It was found that nursing staff in primary healthcare regarded the
planning session as stressful, time-consuming and characterised by a lack of
respect between nursing staff at the hospital and nursing staff in primary
healthcare. They also described uncertainty and hesitation about using video
conferences where patients might probably be the losers and nursing staff the
winners.
Conclusions: It is suggested that there is a need for improvement in
communication and understanding between nursing staff at the hospital and
nursing staff in primary healthcare in order to develop discharge planning.
There is also a need for the nursing staff in primary healthcare to obtain more
information about how Information Technology (IT) solutions could support their
work and help them to find ways to collaborate