Håkan Grahn

Prof. Håkan Grahn

Blekinge Institute of Technology

Research Focus & Metrics

Academic Career Length

32Years (1995-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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29 July 2011 in IEEE Software
Verified
Journal Article
Closed access
CWClaes Wohlin
Claes Wohlin
AAAybuke Aurum
Aybuke Aurum
LALefteris Angelis
Lefteris Angelis
LPLaura Phillips
Laura Phillips
YDYvonne Dittrich
Yvonne Dittrich
JWJeff Winter
Jeff Winter
Collaboration between industry and academia supports improvement and innovation in industry and helps to ensure industrial relevance in academic research. This article presents an exploratory study of the factors for successful collaboration between industry and academia in software research.

29 March 2019 in Neural Computing and Applications
Verified
Journal Article
Open access
PDF file
HKHuseyin Kusetogullari
Huseyin Kusetogullari
AYAmir Yavariabdi
Amir Yavariabdi
ACAbbas Cheddad
Abbas Cheddad
HGHåkan Grahn
Håkan Grahn
JHJohan Hall
Johan Hall
This paper introduces a new image-based handwritten historical digit dataset named Arkiv Digital Sweden (ARDIS). The images in ARDIS dataset are extracted from 15,000 Swedish church records which were written by different priests with various handwriting styles in the nineteenth and twentieth centuries. The constructed dataset consists of three single-digit datasets and one-digit string dataset. The digit string dataset includes 10,000 samples in red–green–blue color space, whereas the other datasets contain 7600 single-digit images in different color spaces. An extensive analysis of machine learning methods on several digit datasets is carried out. Additionally, correlation between ARDIS and existing digit datasets Modified National Institute of Standards and Technology (MNIST) and US Postal Service (USPS) is investigated. Experimental results show that machine learning algorithms, including deep learning methods, provide low recognition accuracy as they face difficulties when trained on existing datasets and tested on ARDIS dataset. Accordingly, convolutional neural network trained on MNIST and USPS and tested on ARDIS provide the highest accuracies $$58.80\%$$ 58.80 % and $$35.44\%$$ 35.44 % , respectively. Consequently, the results reveal that machine learning methods trained on existing datasets can have difficulties to recognize digits effectively on our dataset which proves that ARDIS dataset has unique characteristics. This dataset is publicly available for the research community to further advance handwritten digit recognition algorithms.

19 August 2010 in IEEE Computer Architecture Letters
Verified
Journal Article
Closed access
MIMuhammad Zeeshan Iqbal
Muhammad Zeeshan Iqbal
YLYuchen Liang
Yuchen Liang
HGHåkan Grahn
Håkan Grahn
Multicore processors are the main computing platform in laptops, desktop, and servers today, and are making their way into the embedded systems market also. Using benchmarks is a common approach to evaluate the performance of a system. However, benchmarks for embedded systems have so far been either targeted for a uni-processor environment, e.g., MiBench,or have been commercial, e.g., MultiBench by EEMBC. In this paper, we propose and implement an open source benchmark,ParMiBench, targeted for multiprocessor-based embedded systems. ParMiBench consists of parallel implementations of seven compute intensive algorithms from the uni-processor benchmark suite MiBench. The applications are selected from four domains:Automation and Industry Control, Network, Office, and Security.

18 March 2023 in Electronics
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Journal Article
Open access
PDF file
JDJonne van van Dreven
Jonne van van Dreven
VBVeselka Boeva
Veselka Boeva
SAShahrooz Abghari
Shahrooz Abghari
HGHåkan Grahn
Håkan Grahn
JKJad Al Koussa
Jad Al Koussa
Emilia MotoascaEmilia Motoasca
Emilia Motoasca
This paper presents a comprehensive survey of state-of-the-art intelligent fault detection and diagnosis in district heating systems. Maintaining an efficient district heating system is crucial, as faults can lead to increased heat loss, customer discomfort, and operational cost. Intelligent fault detection and diagnosis can help to identify and diagnose faulty behavior automatically by utilizing artificial intelligence or machine learning. In our survey, we review and discuss 57 papers published in the last 12 years, highlight the recent trends, identify current research gaps, discuss the limitations of current techniques, and provide recommendations for future studies in this area. While there is an increasing interest in the topic, and the past five years have shown much advancement, the absence of open-source high-quality labeled data severely hinders progress. Future research should aim to explore transfer learning, domain adaptation, and semi-supervised learning to improve current performance. Additionally, a researcher should increase knowledge of district heating data using data-centric approaches to establish a solid foundation for future fault detection and diagnosis in district heating.

1 April 2018
Verified
Conference Paper
Closed access
FWFlorian Westphal
Florian Westphal
NLNiklas Lavesson
Niklas Lavesson
HGHåkan Grahn
Håkan Grahn
In the context of document image analysis, image binarization is an important preprocessing step for other document analysis algorithms, but also relevant on its own by improving the readability of images of historical documents. While historical document image binarization is challenging due to common image degradations, such as bleedthrough, faded ink or stains, achieving good binarization performance in a timely manner is a worthwhile goal to facilitate efficient information extraction from historical documents. In this paper, we propose a recurrent neural network based algorithm using Grid Long Short-Term Memory cells for image binarization, as well as a pseudo F-Measure based weighted loss function. We evaluate the binarization and execution performance of our algorithm for different choices of footprint size, scale factor and loss function. Our experiments show a significant trade-off between binarization time and quality for different footprint sizes. However, we see no statistically significant difference when using different scale factors and only limited differences for different loss functions. Lastly, we compare the binarization performance of our approach with the best performing algorithm in the 2016 handwritten document image binarization contest and show that both algorithms perform equally well.

8 November 2022 in Algorithms
Verified
Journal Article
Open access
PDF file
CÅChristoffer Åleskog
Christoffer Åleskog
HGHåkan Grahn
Håkan Grahn
ABAnton Borg
Anton Borg
As machine learning and AI continue to rapidly develop, and with the ever-closer end of Moore’s law, new avenues and novel ideas in architecture design are being created and utilized. One avenue is accelerating AI as close to the user as possible, i.e., at the edge, to reduce latency and increase performance. Therefore, researchers have developed low-power AI accelerators, designed specifically to accelerate machine learning and AI at edge devices. In this paper, we present an overview of low-power AI accelerators between 2019–2022. Low-power AI accelerators are defined in this paper based on their acceleration target and power consumption. In this survey, 79 low-power AI accelerators are presented and discussed. The reviewed accelerators are discussed based on five criteria: (i) power, performance, and power efficiency, (ii) acceleration targets, (iii) arithmetic precision, (iv) neuromorphic accelerators, and (v) industry vs. academic accelerators. CNNs and DNNs are the most popular accelerator targets, while Transformers and SNNs are on the rise.