Blekinge Institute of Technology
Electronic Research Archive - Blekinge Tekniska HögskolaNot a member yet
1855 research outputs found
Sort by
Combined heat & power generation using smart heat grid
No full textCombined heat and power (CHP) generation is often used
when building new district heating production. CHP makes
it possible to simultaneously produce electricity and heat, thus
maximizing the energy efficiency of the primary fuel.
The heat is used in the connected district heating system while the
electricity is sold on the local power market. In a CHP plant it is not
possible to separate the physical process of producing heat and
electricity, which may cause suboptimal behaviour when high spot prices
for power do not coincide with high heat load demand.
This paper presents the design and implementation of a
system which makes it possible to control the heat load demand in a
district heating network in order to optimize the CHP production. By
using artificial intelligence technology in order to automate the run‐time
coordination of the thermal inertia in a large amount of buildings,
it is possible to achieve the same operational benefits as using a large
storage tank, albeit at a substantially less investment and operational cost.
The system continuously considers the climate in each
participating building in order to dynamically ensure that
only the best suited buildings at any given time are actively
participating in load control. Based on the dynamic indoor
climate in each individual building the system automatically
controls and coordinates the charging and discharging of
the buildings thermal buffer without affecting the quality of
service.
This paper describes the overall function of the system
and presents an algorithm for coordinating the thermal
buffer of a large amount of buildings in relation to heat
load demand and spot price projections. Operational data from a small
district heating system in Sweden is used in order to evaluate the
financial and environmental impact of using this technology. The results show
substantial benefits of performing such load control during times of
high spot price volatility
A concept for an interactive search-based software testing system
No full textSoftware is an increasingly important part of various products, although not
always the dominant component. For these software-intensive systems it is
common that the software is assembled, and sometimes even developed, by domain
specialists rather than by software engineers. To leverage the domain
specialists' knowledge while maintaining quality we need testing tools that
require only limited knowledge of software testing. Since each domain has
unique quality criteria and trade-offs and there is a large variation in both
software modeling and implementation syntax as well as semantics it is not easy
to envisage general software engineering support for testing tasks.
Particularly not since such support must allow interaction between the domain
specialists and the testing system for iterative development. In this paper we
argue that search-based software testing can provide this type of general and
interactive testing support and describe a proof of concept system to support
this argument. The system separates the software engineering concerns from the
domain concerns and allows domain specialists to interact with the system in
order to select the quality criteria being used to determine the fitness of
potential solutions
Potential-Field Based navigation in in StarCraft
No full textReal-Time Strategy (RTS) games are a sub-genre of strategy games typically
taking place in a war setting. RTS games provide a rich challenge for both
human- and computer players (bots). Each player has a number of workers for
gathering resources to be able to construct new buildings, train additional
workers, build combat units and do research to unlock more powerful units or
abilities. The goal is to create a strong army and destroy the bases of the
opponent(s). Armies usually consists of a large number of units which must be
able to navigate around the game world. The highly dynamic and real time
aspects of RTS games make pathfinding a challenging task for bots. Typically it
is handled using pathfinding algorithms such as A*, which without adaptions
does not cope very well with dynamic worlds. In this paper we show how a bot
for StarCraft uses a combination of A* and potential fields to better handle
the dynamic aspects of the game
Multi Agent Based Simulation (MABS) of Financial Transactions for Anti Money Laundering (AML)
No full textMobile money is a service for performing financial transactions using a mobile
phone. By law it has to have protection against money laundering and other
types of fraud. Research into fraud detection methods is not as advanced as in
other similar fields. However, getting access to real world data is difficult,
due to the sensitive nature of financial transactions, and this makes research
into detection methods difficult.
Thus, we propose an approach based on a Multi-Agent Based Simulation (MABS) for
the generation of synthetic transaction data. We present the generation of
synthetic data logs of
transactions and the use of such a data set for the study of different
detection scenarios using machine learning
Comorbidity and Sex-Related Differences in Mortality in Oxygen-Dependent Chronic Obstructive Pulmonary Disease
No full textBackground: It is not known why survival differs between men and women in
oxygen-dependent chronic obstructive pulmonary disease (COPD). The present
study evaluates differences in comorbidity between men and women, and tests the
hypothesis that comorbidity contributes to sex-related differences in mortality
in oxygen-dependent COPD.
Methods: National prospective study of patients aged 50 years or older,
starting long-term oxygen therapy (LTOT) for COPD in Sweden between 1992 and
2008. Comorbidities were obtained from the Swedish Hospital Discharge Register.
Sex-related differences in comorbidity were estimated using logistic
regression, adjusting for age, smoking status and year of inclusion. The effect
of comorbidity on overall mortality and the interaction between comorbidity and
sex were evaluated using Cox regression, adjusting for age, sex, Pa-O2
breathing air, FEV1, smoking history and year of inclusion.
Results: In total, 8,712 patients (55% women) were included and 6,729 patients
died during the study period. No patient was lost to follow-up. Compared with
women, men had significantly more arrhythmia, cancer, ischemic heart disease
and renal failure, and less hypertension, mental disorders, osteoporosis and
rheumatoid arthritis (P<0.05 for all odds ratios). Comorbidity was an
independent predictor of mortality, and the effect was similar for the sexes.
Women had lower mortality, which remained unchanged even after adjusting for
comorbidity; hazard ratio 0.73 (95% confidence interval, 0.68-0.77; P<0.001).
Conclusions: Comorbidity is different in men and women, but does not explain
the sex-related difference in mortality in oxygen-dependent COPD
A Comparison of Two MIMO Relaying Protocols in Nakagami- m Fading
No full textTransmit antenna selection with receive maximal-ratio combining (TAS/MRC) and
transmit antenna selection with receive selection combining (TAS/SC) are two
attractive multiple-input–multiple-output (MIMO) protocols. In this paper, we
present a framework for the comparative analysis of TAS/MRC and TAS/SC in a
two-hop amplify-and-forward relay network. In doing so, we derive exact and
asymptotic expressions for
the symbol error rate (SER) in Nakagami-mfading. Using the asymptotic
expressions, the SNR gap between the two protocols is quantified. Given that the
two protocols maintain the same diversity order, we show that
the SNR gap is entirely dependent on the array gain. Motivated by this, we
derive the SNR gap as a simple ratio of the respective array gains of the two
protocols. This ratio explicitly takes into account the impact
of the number of antennas and the fading severity parameter m. In addition, we
address the fundamental question of “How to allocate the total transmit power
between the source and the relay in such a way that
the SER is minimized?” Our answer is given in the form of new compact
expressions for the power allocation factor, which is a practical design tool
that optimally distributes the total transmit power in the network
Resource Consumption in Additive Manufacturing with a PSS Approach
No full textSince the 1980’s, additive manufacturing (AM) has gradually advanced from rapid
prototyping applications towards fabricating end consumer products. Many small
companies may prefer accessing AM technologies through service providers
offering production services as result-oriented Industrial Product-Service
System (IPSS) rather than investing in their own production line. This study
investigated potential benefits of IPSS using system dynamics modeling to study
resource demands between two situations: one where an IPSS approach is used and
one that is the traditional ownership of production equipment. This study
concluded that AM service providers with demand-varying customers could
increase service performance and maximize use of production equipment
Impacts of project-overload on innovation inside organizations: Agent-based modeling
No full textMarket competition and a desire to gain advantages on globalized market, drives
companies towards innovation efforts. Project overload is an unpleasant
phenomenon, which is happening for employees inside those organizations trying
to make the most efficient use of their resources to be innovative. But what
are the impacts of project overload on organization’s innovation capabilities?
Advanced engineering teams (AE) inside a major heavy equipment manufacturer are
suffering from project overload in their quest for innovation. In this paper,
Agent-based modeling (ABM) is used to examine the current reality of the
company context, and of the AE team, where the opportunities and challenges for
reducing the risk of project overload and moving towards innovation were
identified. Project overload is more likely to stifle innovation and creativity
inside teams. On the other hand, motivation on proper challenging goals are
more likely to help individual to alleviate the negative aspects of low level
of project overloa
Intelligent Goods - Characteristics and Architectures
No full textThe transports of goods are continuously increasing in many regions, for
instance within Europe. Often goods travel through many different countries,
using several transport modes and involving a number of different actors. As a
result, the traffic load on the transport network is increasing, on the roads
in particular, and the logistics chains become more and more complex.
Implementing some level of intelligence on the goods, which provide them with
the capabilities to assist in the logistical activities, is one of the
instruments that can be used to make transports and the handling of goods more
efficient and controllable. The concept of intelligent goods both opens up for
new types of services and may be used to improve currently available services.
Our research is mainly focused on the characteristics and possible
architectures of intelligent goods systems. In this context, an intelligent
goods system refers to a number of interacting components (on-board units
(OBU), back-office, RFID tags, etc.), including intelligent goods, which
together provide services. The architecture studies are focused on which
information and data processing are needed, where they should be stored and
which communication links are required. By identifying architectures
corresponding to different service solutions, intelligent goods can be valued
against other types of solutions, for instance more centralized configurations.
In particular, different situations and services put different requirements on
a system and the benefits of using intelligent goods vary.
We present a framework which can be used to describe intelligent goods systems,
including the capabilities of the goods, necessary information entities related
to the goods as well as the surrounding entities, primitive functions and the
environment around the goods. Additionally, we identify a number of primitive,
potential intelligent goods level services which can be used as building blocks
when creating more advanced intelligent goods services. The functional and
information requirements of these services are also investigated. Based on
these findings, a new approach for how to identify and evaluate different
architectural solutions for potential intelligent goods services is suggested.
Furthermore, a new service description framework is proposed, which can be used
to, amongst others, define a service and to perform composition/decomposition
analyses. Finally, an investigation of how agent technology can be used to
model intelligent goods systems is also presented
On the Performance Analysis of Cooperative Communications with Practical Constraints
No full textWith the rapid development of multimedia services, wireless communication
engineers may face a major challenge to meet the demand of higher data-rate
communication over error-prone mobile radio channels. As a promising solution,
the concept of cooperative communication, where a so-called relay node is
formed to assist the direct link, has recently been applied to alleviate the
severe pathloss and shadowing effects in wireless systems. In addition, without
spending extra spectrum and power resources, multiple-input multiple-output
(MIMO) antenna systems have been shown to provide an immense improvement in
system performance compared to its single-antenna counterpart. As such,
cooperative MIMO communication is essential for wireless and mobile networks
because of its remarkable increase in spectral efficiency and reliability.
Although the utilization of cooperative communication in MIMO systems has
gained great attention in the literature, most of the research works have
assumed perfect conditions. Inspired by the aforementioned discussion, this
thesis takes a step further to investigate the performance of cooperative
communications with practical constraints. The thesis provides a general
framework for performance analysis of cooperative communications subject to
several practical constraints such as antenna correlation, rank-deficiency of
the channel matrix, co-channel interference, and interference-limited
constraint of cognitive radio networks based on an underlay spectrum-sharing
approach.
The thesis is divided into six parts. The first part investigates the
performance of orthogonal space-time block codes (OSTBCs) over MIMO relay
networks in Nakagami-m fading channels under the antenna correlation effect.
The second part extends the full-rank MIMO channel to the case of the MIMO
channel matrix being of rank-deficiency. Several important findings on the
impact of the single-keyhole effect (SKE) and double-keyhole effect (DKE) are
observed for two types of amplifying mechanism at the relay, namely, linear and
squaring approaches. An important observation corroborated by our studies is
that for offering a tradeoff between performance and complexity, we should use
the linear approach for SKE and the squaring approach for DKE. The third part
generalizes the keyhole effect to multi-keyhole channels.
The exact and asymptotic expressions for symbol error probability (SEP) are
derived for some specific cases such as multi-keyhole MIMO/multiple-input
single-output (MISO) channel. The fourth part proposes a distributed Alamouti
space-time code for two-way fixed gain amplify-and-forward (AF) relaying.
In particular, closed-form expressions for approximated ergodic sum-rate and
exact pairwise error probability (PWEP) are derived for Nakagami-m fading
channels. To reveal further insights into array and diversity gains, an
asymptotic PWEP is also obtained. The fifth part analyzes the outage
performance of a two-way fixed gain AF relay system with beamforming, arbitrary
antenna correlation, and co-channel interference (CCI). Finally, the sixth part
investigates the impact of interference power constraint on the performance of
cognitive relay networks based on the spectrum-sharing approach