Lars Lundberg

Lars Lundberg
Blekinge Institute of Technology | BTH

About

207
Publications
59,201
Reads
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1,726
Citations
Citations since 2016
37 Research Items
525 Citations
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2016201720182019202020212022020406080
2016201720182019202020212022020406080
2016201720182019202020212022020406080
Introduction
Skills and Expertise

Publications

Publications (207)
Article
Full-text available
The availability of large amounts of data in combination with Big Data analytics has transformed many application domains. In this paper, we provide insights into how the area has developed in the last decade. First, we identify seven major application areas and six groups of important enabling technologies for Big Data applications and systems. Th...
Article
Full-text available
Large amount of data are generated from in-situ monitoring of additive manufacturing (AM) processes which is later used in prediction modelling for defect classification to speed up quality inspection of products. A high volume of this process data is defect-free (majority class) and a lower volume of this data has defects (minority class) which re...
Article
Full-text available
Advances in 5G and the Internet of Things (IoT) have to cater to the diverse and varying needs of different stakeholders, devices, sensors, applications, networks, and access technologies that come together for a dedicated IoT network for a synergistic purpose. Therefore, there is a need for a solution that can assimilate the various requirements a...
Conference Paper
This paper aims to address data labelling issues in process data to support in-situ process monitoring of additive manufactured components. For this, we adopted an active learning (AL) approach to minimise the manual effort for data labelling for classification models. In this study, we present an approach that utilises pre-trained models to extrac...
Article
Full-text available
In railway traffic systems, whenever disturbances occur, it is important to effectively reschedule trains while optimizing the goals of various stakeholders. Algorithms can provide significant benefits to support the traffic controllers in train rescheduling, if well integrated into the overall traffic management process. In the railway research li...
Preprint
Full-text available
In railway traffic systems, it is essential to achieve a high punctuality to satisfy the goals of the involved stakeholders. Thus, whenever disturbances occur, it is important to effectively reschedule trains while considering the perspectives of various stakeholders. This typically involves solving a multi-objective train rescheduling problem, whi...
Chapter
Full-text available
Emerging scenarios for the "Internet of Things" (IoT) require a dedicated software defined network over the conventional communication network provided by the different service providers and free to use communication methodologies. These IoT networks have their own dedicated requirements, based on the different stakeholders involved in it, which ca...
Chapter
Cluster validation measures are designed to find the partitioning that best fits the underlying data. In this study, we show that these measures can be used for identifying mislabeled instances or class outliers prior to training in supervised learning problems. We introduce an ensemble technique, entitled CVI-based Outlier Filtering, which identif...
Book
The “HPI Future SOC Lab” is a cooperation of the Hasso Plattner Institute (HPI) and industry partners. Its mission is to enable and promote exchange and interaction between the research community and the industry partners. The HPI Future SOC Lab provides researchers with free of charge access to a complete infrastructure of state of the art hard an...
Article
Full-text available
NoSQL distributed databases are often used as Big Data platforms. To provide efficient resource sharing and cost effectiveness, such distributed databases typically run concurrently on a virtualized infrastructure that could be implemented using hypervisor‐based virtualization or container‐based virtualization. Hypervisor‐based virtualization is a...
Article
Full-text available
We consider a real-time application that executes in a VM with multiple virtual cores. Tasks are scheduled globally using fixed-priority scheduling. In order to avoid Dhall’s effect, we classify tasks into two priority classes: heavy and light. Heavy tasks have higher priority than light tasks. For light tasks we use rate monotonic priority assignm...
Article
Full-text available
The main resource for any telecom operator is the physical radio cell network. We present two related methods for optimizing the utilization in radio networks: Tetris optimization and selective cell expansion. Tetris optimization tries to find the mix of users from different market segments that provides the most even load in the network. Selective...
Conference Paper
Full-text available
We present a new method, called hyperplane folding, that increases the margin in Support Vector Machines (SVMs). Based on the location of the support vectors, the method splits the dataset into two parts, rotates one part of the dataset and then merges the two parts again. This procedure increases the margin as long as the margin is smaller than ha...
Conference Paper
Full-text available
As pointed out by Zadeh, the mission of fuzzy logic in the era of big data is to create a relevant summary of huge amounts of data and facilitate decision making. In this study, elements of fuzzy set theory are used to create a visual summary of telecom data, which gives a comprehensive idea concerning the desirability of boosting an operator's pre...
Article
Full-text available
In this work, we apply cluster validation measures for analyzing email communications at an organizational level of a company. This analysis can be used to evaluate the company structure and to produce further recommendations for structural improvements. Our evaluations, based on data in the forms of email logs and organizational structure for a la...
Article
Full-text available
One of the crucial factors in achieving a high punctuality in railway traffic systems, is the ability to effectively reschedule the trains when disturbances occur. The railway traffic rescheduling problem is a complex task to solve both from a practical and a computational perspective. Problems of practically relevant sizes have typically a very la...
Conference Paper
Full-text available
The population in Sweden is growing rapidly due to immigration. In this light, the issue of infrastructure upgrades to provide telecommunication services is of importance. New antennas can be installed at hot spots of user demand, which will require an investment, and/or the clientele expansion can be carried out in a planned manner to promote the...
Article
Full-text available
Apache Cassandra is an highly scalable and available NoSql datastore, largely used by enterprises of each size and for application areas that range from entertainment to big data analytics. Managed Cassandra service providers are emerging to hide the complexity of the installation, fine tuning and operation of Cassandra Virtual Data Centers (VDCs)....
Conference Paper
Full-text available
A major investment made by a telecom operator goes into the infrastructure and its maintenance, while business revenues are proportional to how big and good the customer base is. We present a data-driven analytic strategy based on combinatorial optimization and analysis of historical data. The data cover historical mobility of the users in one regi...
Chapter
Full-text available
In telecommunication business, a major investment goes into the infrastructure and its maintenance, while business revenues are proportional to how big, good, and well-balanced the customer base is. We present a data-driven analytic strategy based on combinatorial optimization and analysis of the historical mobility designed to quantify the desirab...
Conference Paper
Full-text available
In business analytics some industries rely heavily on commercial geo-demographic segmentation systems (MOSAIC, ACORN, etc.), which are a universally strong predictor of user's behavior: from diabetes propensity and purchasing habits to political preferences. A segment is defined with a postcode of the client's home address. Recent research suggests...
Article
Full-text available
A major investment made by a telecom operator goes into the infrastructure and its maintenance, while business revenues are proportional to how big and good the customer base is. We present a data-driven analytic strategy based on combinatorial optimization and analysis of historical data. The data cover historical mobility of the users in one regi...
Article
Full-text available
The population in Sweden is growing rapidly due to immigration. In this light, the issue of infrastructure upgrades to provide telecommunication services is of importance. New antennas can be installed at hot spots of user demand, which will require an investment, and/or the clientele expansion can be carried out in a planned manner to promote the...
Technical Report
Full-text available
The revenue of a cellular network is proportional to the number of subscribers that can use it without overloading any radio cell. The mobility pattern of the subscribers affects the load in the network. Based on data from a region in Sweden, we have evaluated two optimization strategies: Tetris optimization and cell expansion. Tetris optimization...
Poster
Full-text available
Platforms for big data includes mechanisms and tools to model, organize, store and access big data (e.g. Apache Cassandra, Hbase, Amazon SimpleDB, Dynamo, Google BigTable). The resource management for those platforms is a complex task and must account also for multi-tenancy and infrastructure scalability. Human assisted control of Big data platform...
Conference Paper
Apache Cassandra is a NoSql database offering high scalability and availability. Among with its competitors, e.g. Hbase, SympleDB and BigTable, Cassandra is a widely used platform for big data systems. Tuning the performance of those systems is a complex task and there is a growing demand for autonomic management solutions. In this paper we present...
Conference Paper
Full-text available
In this study, we evaluate the performance of trajectory queries that are handled by Cassandra, MongoDB, and PostgreSQL. The evaluation is conducted on a multiprocessor and a cluster. Telecommunication companies collect a lot of data from their mobile users. These data must be analysed in order to support business decisions, such as infrastructure...
Technical Report
Full-text available
This project focuses on the analysis of spatial data collected by Telenor Sweden. The project has two objectives: 1) developing the methods for spatial data analytics, and 2) finding an optimal technology to turn research prototype into scalable industrial application. The two main findings are as follows. Firstly, a smart marketing campaign based...
Conference Paper
There are two levels of scheduling in real-time applications executing in a virtualized environment: traditional real-time scheduling of the tasks in the real-time application inside a Virtual Machine (VM), and scheduling of different VMs on the hypervisor level. In order to save more resources, we propose to schedule VMs that contains hard real-ti...
Conference Paper
We have done a usability evaluation of a mobile commerce system developed by Ericsson in Sweden. The main market for the system is in developing countries in Africa. Consequently, there is a geographical distance between the developers and the users, and it is difficult to involve actual users in usability tests. Because of this, a team of solution...
Conference Paper
A major advantage of cloud environments is that one can balance the load by migrating virtual machines (VMs) from one server to another. High performance and high resource utilization are also important in a cloud. We have observed that over-allocation of virtual CPUs to VMs (i.e. allocating more vCPUs to VMs than there CPU cores on the server) whe...
Article
We present two strategies to balance the load in a system with multiple virtual machines (VMs) through automated live migration. When the push strategy is used, overloaded hosts try to migrate workload to less loaded nodes. On the other hand, when the pull strategy is employed, the light-loaded hosts take the initiative to offload overloaded nodes....
Article
The possibility to migrate a virtual server from one physical computer in a cloud to another physical computer in the same cloud is important in order to obtain a balanced load. In order to facilitate live migration of virtual servers, one needs to provide large shared storage systems that are accessible for all the physical servers that are used i...
Conference Paper
This paper quantifies the performance of the core part of voice driven web using free and open source speech engine; the speech engine which is very high computation demanding, it consists of Automatic Speech Recognition (ASR) and Text To Speech (TTS). Two open source programs, Sphinx-4 and FreeTTS-1.2.2 are used for ASR and TTS respectively. These...
Article
The number of applications that use virtualized cloud-based systems is growing, and one would like to use this kind of systems also for real-time applications with hard deadlines. There is scheduling on two levels in real-time applications executing in a virtualized environment: traditional real-time scheduling of the tasks in the real-time applica...
Conference Paper
We have evaluated the performance of Cauchy Reed-Solomon (CRS) encoding of data blocks with sizes 32 kB to 256 MB. The performance measurements are done on an Intel processor with 4 cores and integrated graphics support. We also used an AMD graphics card in our performance evaluations. Three versions of the CRS algorithm are developed: one sequenti...
Conference Paper
Real-time video streaming suffer from bandwidth limitation that are unable to handle the high amount of video data. To reduce the amount of data to be streamed, we propose an adaptive technique to crop the important part of the video frames, and drop the part that are outside the important part; this part is called the Region of Interest (ROI). The...
Article
Software security can be improved by identifying and correcting vulnerabilities. In order to reduce the cost of rework, vulnerabilities should be detected as early and efficiently as possible. Static automated code analysis is an approach for early detection. So far, only few empirical studies have been conducted in an industrial context to evaluat...
Article
Full-text available
In real time video streaming, the frames must meet their timing constraints, typically specified as their deadlines. Wireless networks may suffer from bandwidth limitations. To reduce the data transmission over the wireless networks, we propose an adaption technique in the server side by extracting a part of the video frames that considered as a Re...
Conference Paper
Streaming real time video over wireless networks cannot guarantee that all the frames could meet their deadlines. Wireless networks may suffer from bandwidth limitations. To reduce the streaming data over wireless networks, we propose a technique to identify, and extract the Region Of Interest (ROI), and drop the non-ROI from the frames that are be...
Conference Paper
This paper quantifies the implications and trade-offs of three different architectures for voice driven web application, architectures are implemented as prototypes. The prototypes differ from each other by either using recording, or Text To Speech (TTS) as server based, or TTS as client based to process output speech. A typical application used in...
Article
Full-text available
Distributed Computing and Networking International audience For a parallel computer system with m identical computers, we study optimal performance precaution for one possible computer crash. We want to calculate the cost of crash precaution in the case of no crash. We thus define a tolerance level r meaning that we only tolerate that the completio...
Article
Real-time video streaming over wireless channel has become an important issue due to the limited bandwidth that is unable to handle the flow of information of the video frames. The characteristics of wireless networks in terms of the available bandwidth, frame delay, and frame losses cannot be known in advance. As the effect of that, the user may n...
Article
We provide a constant time schedulability test and priority assignment algorithm for an on-line multiprocessor server handling aperiodic tasks. The so called Dhall’s effect is avoided by dividing tasks in two priority classes based on their utilization: heavy and light. The improvement in this paper is due to assigning priority of light tasks based...
Article
Full-text available
Streaming video over a wireless network faces several challenges such as high packet error rates, bandwidth variations, and delays, which could have negative effects on the video streaming and the viewer will perceive a frozen picture for certain durations due to loss of frames. In this study, we propose a Time Interleaving Robust Streaming (TIRS)...
Conference Paper
Full-text available
Real time video streaming suffers from lost, delayed, and corrupted frames due to the transmission over error prone channels. As an effect of that, the user may notice a frozen picture in their screen. In this work, we propose a technique to eliminate the frozen video and provide a satisfactory quality to the mobile viewer by splitting the video fr...
Conference Paper
Full-text available
Transmitting a real time video streaming over a wireless network cannot guarantee that all the frames could be received by the mobile devices. The characteristics of a wireless network in terms of the available bandwidth, frame delay, and frame losses cannot be known in advanced. In this work, we propose a new mechanism for streaming video over a w...
Conference Paper
Full-text available
The main challenge of real time video streaming over a wireless network is to provide good quality service (QoS) to the mobile viewer. However, wireless networks have a limited bandwidth that may not be able to handle the continues video frame sequence and also with the possibility that video frames could be dropped or corrupted during the transmis...
Article
We consider the optimal makespan C(P, m, i) of an arbitrary set P of independent jobs scheduled with i preemptions on a multiprocessor with m identical processors. We compare the ratio for such makespans for i and j preemptions, respectively, where i j. This ratio depends on P, but we are interested in the P that maximizes this ratio, i.e. we calcu...
Conference Paper
Full-text available
Code reviews with static analysis tools are today recommended by several security development processes. Developers are expected to use the tools' output to detect the security threats they themselves have introduced in the source code. This approach assumes that all developers can correctly identify a warning from a static analysis tool (SAT) as a...
Conference Paper
This conceptual paper focuses on revealing challenges and offering concepts associated with the incorporation of the quality of experience (QoE) paradigm into the design of mobile video systems. The corresponding design framework combines application, middleware and networking layer in a unique cross-layer approach, in which all layers shall jointl...
Article
Full-text available
The ongoing transition from uniprocessor to multiprocessor computers requires support from the operating system kernel. Although many general-purpose multiprocessor operating systems exist, there is a large number of specialized operating systems which require porting in order to work on multiprocessors. In this paper we describe the multiproce...
Article
Real-time video transmission over wireless channels has become an important topic in wireless communication because of the limited bandwidth of wireless network that should handle high amount of video frames. Video frames must arrive at the client before the playout time with enough time to display the contents of the frames. Real-time video tr...
Article
Agent platforms provide a framework for development and execution of parallel applications such as multi-agent based simulation (MABS). However, these platforms have limitations to support large-scale MABS applications in practice. This paper aims at investigating and improving the performance of an agent platform with a MABS workload in distribute...
Article
Analysis of anomalies reported during testing of a project can tell a lot about how well the processes and products work. Still, organizations rarely use anomaly reports for more than progress tracking although projects commonly spend a significant part of the development time on finding and correcting faults. This paper presents an anomaly metrics...
Article
Full-text available
Proposal for a 2+2 year research project within PAMP 1. Short summary Large telecommunication applications running in real-time environments need to have high, predictable and scalable performance. Parallel (multithreaded) programs and multiprocessors is one way to achieve this. However, the experi-ence of writing parallel programs is still limited...