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  • 151.
    Ahlgren, Bengt
    RISE, Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    NetInf Routing Using Hints2013Conference paper (Refereed)
    Abstract [en]

    We define a global routing mechanism for the NetInf protocol, part of the NetInf information-centric networking architecture. The mechanism makes use of two levels of aggregation in order to provide the scalability needed for a global network. An anticipated $10^{15}$ number of individual named data objects are aggregated to in the order of 500K routing hints which are very feasible to handle with existing routing technology. The hints are then used to forward requests for named data towards the publisher.

  • 152.
    Ahlgren, Bengt
    et al.
    RISE, Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    Andersson, Anders
    Hagsand, Olof
    RISE - Research Institutes of Sweden, ICT, SICS.
    Marsh, Ian
    RISE - Research Institutes of Sweden, ICT, SICS.
    Dimensioning links for IP telephony2001In: Proceedings of the 2nd IP-Telephony Workshop (IPtel 2001), 2-3 April 2001, New York City, New York, USA, 2001, 1Conference paper (Refereed)
    Abstract [en]

    Packet loss is an important parameter for dimensioning network links or traffic classes carrying IP telephony traffic. We present a model based on the Markov modulated Poisson process (MMPP) which calculates packet loss probabilities for a set of super positioned voice input sources and the specified link properties. We do not introduce another new model to the community, rather try and verify one of the existing models via extensive simulation and a real world implementation. A plethora of excellent research on queuing theory is still in the domain of ATM researchers and we attempt to highlight its validity to the IP Telephony community. Packet level simulations show very good correspondence with the predictions of the model. Our main contribution is the verification of the MMPP model with measurements in a laboratory environment. The loss rates predicted by the model are in general close to the measured loss rates and the loss rates obtained with simulation. The general conclusion is that the MMPP-based model is a tool well suited for dimensioning links carrying packetized voice in a system with limited buffer space.

  • 153.
    Ahlgren, Bengt
    et al.
    RISE, Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    Andersson, Anders
    RISE - Research Institutes of Sweden, ICT, SICS.
    Hagsand, Olof
    RISE - Research Institutes of Sweden, ICT, SICS.
    Marsh, Ian
    RISE - Research Institutes of Sweden, ICT, SICS.
    Dimensioning Links for IP Telephony2000Report (Other academic)
    Abstract [en]

    Transmitting telephone calls over the Internet causes problems not present in current telephone technology such as packet loss and delay due to queueing in routers. In this undergraduate thesis we study how a Markov modulated Poisson process is applied as an arrival process to a multiplexer and we study the performance in terms of loss probability. The input consists of the superposition of independent voice sources. The predictions of the model is compared with results obtained with simulations of the multiplexer made with a network simulator. The buffer occupancy distribution is also studied and we see how this distribution changes as the load increases.

  • 154.
    Ahlgren, Bengt
    et al.
    RISE, Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    Aranda, Pedro A.
    Chemouil, Prosper
    Correia, Luis M.
    Holger, Karl
    Oueslati, Sara
    Söllner, Michael
    Welin, Annikki
    Content, Connectivity and Cloud: Ingredients for the Network of the Future2011In: IEEE Communications Magazine, ISSN 0163-6804, E-ISSN 1558-1896, Vol. 49, p. 62-70Article in journal (Refereed)
    Abstract [en]

    A new network architecture for the Internet needs ingredients from three approaches: information-centric networking, cloud computing integrated with networking, and open connectivity. Information-centric networking considers pieces of information as first-class entities of a networking architecture, rather than only indirectly identifying and manipulating them via a node hosting that information; this way, information becomes independent from the devices they are stored in, enabling efficient and application-independent information caching in the network. Cloud networking offers a combination and integration of cloud computing and virtual networking. It is a solution that distributes the benefits of cloud computing more deeply into the network, and provides a tighter integration of virtualisation features at computing and networking levels. To support these concepts, open connectivity services need to provide advanced transport and networking mechanisms, making use of network and path diversity (even leveraging direct optical paths) and encoding techniques, and dealing with ubiquitous mobility of user, content and information objects in a unified way.

  • 155.
    Ahlgren, Bengt
    et al.
    RISE, Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    Björkman, Mats
    Multimedia transport service and protocol issues1992Report (Other academic)
    Abstract [en]

    This paper considers the issues of a real time transport service needed by multimedia applications for transferring digital video and audio. Three classes of transport service are defined with different levels of real time constraints. Methods for error control are considered for the classes, and the classes are discussed with respect to the application requirements.

  • 156.
    Ahlgren, Bengt
    et al.
    RISE, Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    Björkman, Mats
    Gunningberg, Per
    Integrated layer processing can be hazardous to your performance1997Conference paper (Refereed)
    Abstract [en]

    Integrated Layer Processing (ILP) has been presented as an implementation technique to improve communication protocol performance by reducing the number of memory references. Previous research has however not pointed out that in some circumstances ILP can significantly increase the number of memory references, resulting in lower communication throughput. We explore the performance effects of applying ILP to data manipulation functions with varying characteristics. The functions are generated from a set of parameters including input and output block size, state size and number of instructions. We present experimental data for varying function state sizes, number of integrated functions and instruction counts. The results clearly show that the aggregated state of the functions must fit in registers for ILP to be competitive.

  • 157.
    Ahlgren, Bengt
    et al.
    RISE, Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    Björkman, Mats
    Gunningberg, Per
    RISE - Research Institutes of Sweden, ICT, SICS.
    The applicability of integrated layer processing1998In: IEEE Journal on Selected Areas in Communications, Vol. 16, no 3, p. 317-331Article in journal (Refereed)
    Abstract [en]

    In this paper we review previous work on the applicability and performance of Integrated Layer Processing (ILP). ILP has been shown to clearly improve computer communication performance when integrating simple data manipulation functions, but the situation has been less clear for more complex functions and complete systems. We discuss complications when applying ILP to protocol stacks, the requirements of ILP on the communication subsystem, caching aspects, the importance of the processor registers, and a model for predicting the performance of data manipulation functions. We conclude that the main drawback of ILP is its limited aplicability to complex data manipulation functions. The performance to expect from an ILP implementation also depends heavily on the protocol architecture and the host system architecture.

  • 158.
    Ahlgren, Bengt
    et al.
    RISE, Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    Björkman, Mats
    Gunningberg, Per
    RISE - Research Institutes of Sweden, ICT, SICS.
    Towards predictable ILP performance-controlling communication buffer cache effects1995Conference paper (Refereed)
  • 159.
    Ahlgren, Bengt
    et al.
    RISE, Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    Björkman, Mats
    Gunningberg, Per
    Towards predictable ILP performance-controlling communication buffer cache effects1996In: The Australian Computer Journal, Vol. 28, p. 66-71Article in journal (Refereed)
    Abstract [en]

    Cache memory behavior is becoming more and more important as the speed of CPUs is increasing faster than the speed of memories. The operation of caches are statistical which means that the system level performance becomes unpredictable. In this paper we investigate the worst case behavior of cache line conflicts in the context of communication protocols implemented using Integrated Layer Processing. The goal of our work is to control the cache by placing communication buffers and code in non-conflicting positions in the cache. The result would be higher and more predictable performance. Our first results indicate that the worst case behavior can be up to almost four times slower than the best case.

  • 160.
    Ahlgren, Bengt
    et al.
    RISE, Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    Björkman, Mats
    Moldeklev, Kjersti
    The performance of a no-copy API for communication1995Conference paper (Refereed)
    Abstract [en]

    We present a so-called no-copy Application Programming Interface (API) for communication. The interface avoids copying when data is transferred between the application and operating system kernel address spaces. The API is an extension to the socket interface for SunOS, and has been implemented on Sun SPARCstations equipped with Fore Systems ATM adapters. Throughput for the no-copy API is 85 Mbit/s for 8K UDP messages, to be compared to 57 Mbit/s for the regular API on the SPARCstation 2. Processing times through the TCP and UDP stacks are reduced by up to 30% for the SPARCstation 2 and by more than 50% for the SPARCstation 10.

  • 161.
    Ahlgren, Bengt
    et al.
    RISE, Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    Brunner, Marcus
    Eggert, Lars
    Hancock, Robert
    Schmid, Stefan
    Invariants: A New Design Methodology for Network Architectures2004Conference paper (Refereed)
    Abstract [en]

    The first age of Internet architectural thinking concentrated on defining the correct principles for designing a packet-switched network and its application protocol suites. Although these same principles remain valid today, they do not address the question of how to reason about the evolution of the Internet or its interworking with other networks of very different heritages. This paper proposes a complementary methodology, motivated by the view that evolution and interworking flexibility are determined not so much by the principles applied during initial design, but by the choice of fundamental components or "design invariants" in terms of which the design is expressed. The paper discusses the characteristics of such invariants, including examples from the Internet and other networks, and considers what attributes of invariants best support architectural flexibility.

  • 162.
    Ahlgren, Bengt
    et al.
    RISE, Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    D’Ambrosio, Matteo
    4WARD.
    Dannewitz, Christian
    4WARD.
    Marchisio, Marco
    Marsh, Ian
    RISE - Research Institutes of Sweden, ICT, SICS.
    Ohlman, Börje
    Pentikousis, Kostas
    Rembarz, René
    Strandberg, Ove
    Vercellone, Vinicio
    Design considerations for a network of information2008Conference paper (Refereed)
    Abstract [en]

    The existing Internet ecosystem is a result of decades of evolution. It has managed to scale well beyond the original aspirations. Evolution, though, highlighted a certain degree of inadequacies that is well documented. In this position paper we present the design considerations for a re-architected global networking architecture which delivers dissemination and non-dissemination objects only to consenting recipients, reducing unwanted traffic, linking information producers with consumers independently of the hosts involved, and connects the digital with the physical world. We consider issues ranging from the proposed object identifier/locator split to security and trust as we transition towards a Network of Information and relate our work with the emerging paradigm of publish/subscribe architectures. We introduce the fundamental components of a Network of Information, i.e., name resolution, routing, storage, and search, and close this paper with a discussion about future work.

  • 163.
    Ahlgren, Bengt
    et al.
    RISE, Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    Dannewitz, Christian
    University of Paderborn, Germany.
    Imbrenda, Claudio
    NEC Laboratories Europe, Germany.
    Kutscher, Dirk
    NEC Laboratories Europe, Germany.
    Ohlman, Börje
    Ericsson, Germany.
    A Survey of Information-Centric Networking2012In: IEEE Communications Magazine, ISSN 0163-6804, E-ISSN 1558-1896, Vol. 50, p. 26-36Article in journal (Refereed)
    Abstract [en]

    The information-centric networking (ICN) concept is a significant common approach of several Future Internet research activities. The approach leverages in-network caching, multi-party communication through replication, and interaction models decoupling senders and receivers. The goal is to provide a network infrastructure service that is better suited to today's use, in particular content distribution and mobility, and that is more resilient to disruptions and failures. The ICN approach is being explored by a number of research projects. We compare and discuss design choices and features of proposed ICN architectures, focussing on the following main components: named data objects, naming and security, API, routing and transport, and caching. We also discuss the advantages of the ICN approach in general.

  • 164.
    Ahlgren, Bengt
    et al.
    RISE, Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    Dannewitz, Christian
    Imbrenda, Claudio
    Kutscher, Dirk
    Ohlman, Börje
    A Survey of Information-Centric Networking (Draft)2011Conference paper (Refereed)
  • 165.
    Ahlgren, Bengt
    et al.
    RISE, Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    Eggert, Lars
    Ohlman, Börje
    Rajahalme, Jarno
    Schieder, Andreas
    Names, addresses and identities in ambient networks2005Conference paper (Refereed)
    Abstract [en]

    Ambient Networks interconnect independent realms that may use different local network technologies and may belong to different administrative or legal entities. At the core of these advanced internetworking concepts is a flexible naming architecture based on dynamic indirections between names, addresses and identities. This paper gives an overview of the connectivity abstractions of Ambient Networks and then describes its naming architecture in detail, comparing and contrasting them to other related next-generation network architectures.

  • 166.
    Ahlgren, Bengt
    et al.
    RISE, Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    Eggert, Lars
    Ohlman, Börje
    Schieder, Andreas
    Ambient networks: Bridging heterogeneous network domains2005Conference paper (Refereed)
    Abstract [en]

    Providing end-to-end communication in heterogeneous internetworking environments is a challenge. Two fundamental problems are bridging between different internetworking technologies and hiding of network complexity and differences from both applications and application developers. This paper presents abstraction and naming mechanisms that address these challenges in the Ambient Networks project. Connectivity abstractions hide the differences of heterogeneous internetworking technologies and enable applications to operate across them. A common naming framework enables end-to-end communication across otherwise independent internetworks and supports advanced networking capabilities, such as indirection or delegation, through dynamic bindings between named entities.

  • 167.
    Ahlgren, Bengt
    et al.
    RISE - Research Institutes of Sweden, ICT, SICS.
    Grinnemo, Karl-Johan
    Karlstad University, Sweden.
    Abrahamsson, Henrik
    RISE - Research Institutes of Sweden, ICT, SICS.
    Brunstrom, Anna
    Karlstad University, Sweden.
    Hurtig, Per
    Karlstad University, Sweden.
    Latency-aware Multipath Scheduling in Information-centric Networks2019In: Proceedings of the 15th Swedish National Computer Networking Workshop (SNCNW), 2019Conference paper (Other academic)
    Abstract [en]

    We present the latency-aware multipath scheduler ZQTRTT that takes advantage of the multipath opportunities in information-centric networking. The goal of the scheduler is to use the (single) lowest latency path for transaction-oriented flows, and use multiple paths for bulk data flows. A new estimator called zero queue time ratio is used for scheduling over multiple paths. The objective is to distribute the flow over the paths so that the zero queue time ratio is equal on the paths, that is, so that each path is ‘pushed’ equally hard by the flow without creating unwanted queueing. We make an initial evaluation using simulation that shows that the scheduler meets our objectives.

  • 168.
    Ahlgren, Bengt
    et al.
    RISE, Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    Gunningberg, Per
    A minimal-copy network interface architecture supporting ILP and ALF1994Conference paper (Refereed)
  • 169.
    Ahlgren, Bengt
    et al.
    RISE, Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    Gunningberg, Per
    RISE - Research Institutes of Sweden, ICT, SICS.
    Moldeklev, Kjersti
    Increasing communication performance with a minimal-copy data path supporting ILP and ALF1996In: Journal of High Speed Networks, Vol. 5, no 2, p. 203-214Article in journal (Refereed)
    Abstract [en]

    Many current implementations of communication subsystems on workstation class computers transfer communication data to and from primary memory several times. This is due to software copying between user and operating system address spaces, presentation layer data conversion and other data manipulation functions. The consequence is that memory bandwidth is one of the major performance bottlenecks limiting high speed communication on these systems. We propose a communication subsystem architecture with a minimal-copy data path to widen this bottleneck. The architecture is tailored for protocol implementations using Integrated Layer Processing (ILP) and Application Layer Framing (ALF). We choose to implement these protocols in the address space of the application program. We present a new application program interface (API) between the protocols and the communication service in the operating system kernel. The API does not copy data, but instead passes pointers to page size data buffers. We analyze and discuss ILP loop and cache memory requirements on these buffers. Initial experiments show that the API can increase the communication performance with 50% compared to a standard BSD Unix socket interface.

  • 170.
    Ahlgren, Bengt
    et al.
    RISE, Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    Hidell, Markus
    KTH Royal Institute of Technology, Sweden.
    Ngai, Edith
    Uppsala University, Sweden.
    Internet of Things for Smart Cities: Interoperability and Open Data2016In: IEEE Internet Computing, ISSN 1089-7801, E-ISSN 1941-0131, Vol. 20, no 6, p. 52-56Article in journal (Refereed)
    Abstract [en]

    The Internet of Things (IoT) for smart cities needs accessible open data and open systems, so that industries and citizens can develop new services and applications. As an example, the authors provide a case study of the GreenIoT platform in Uppsala, Sweden.

  • 171.
    Ahlgren, Bengt
    et al.
    RISE, Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    Hurtig, Per
    Abrahamsson, Henrik
    RISE, Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    Grinnemo, Karl-Johan
    Brunstrom, Anna
    Are MIRCC and Rate-based Congestion Control in ICN READY for Variable Link Capacity?2017Conference paper (Refereed)
    Abstract [en]

    Information-centric networking~(ICN) has been introduced as a potential future networking architecture. ICN promises an architecture that makes information independent from location, application, storage, and transportation. Still, it is not without challenges. Notably, there are several outstanding issues regarding congestion control: Since ICN is more or less oblivious to the location of information, it opens up for a single application flow to have several sources, something which blurs the notion of transport flows, and makes it very difficult to employ traditional end-to-end congestion control schemes in these networks. Instead, ICN networks often make use of hop-by-hop congestion control schemes. However, these schemes are also tainted with problems, e.g., several of the proposed ICN congestion controls assume fixed link capacities that are known beforehand. Since this seldom is the case, this paper evaluates the consequences in terms of latency, throughput, and link usage, variable link capacities have on a hop-by-hop congestion control scheme, such as the one employed by the Multipath-aware ICN Rate-based Congestion Control~(MIRCC). The evaluation was carried out in the OMNeT++ simulator, and demonstrates how seemingly small variations in link capacity significantly deteriorate both latency and throughput, and often result in inefficient network link usage.

  • 172.
    Ahlgren, Bengt
    et al.
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Hurtig, Per
    Karlstad University, Sweden.
    Abrahamsson, Henrik
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Grinnemo, Karl-Johan
    Karlstad University, Sweden.
    Brunstrom, Anna
    Karlstad University, Sweden.
    ICN congestion control for wireless links2018Conference paper (Refereed)
    Abstract [en]

    Information-centric networking (ICN) with its design around named-based forwarding and in-network caching holds great promises to become a key architecture for the future Internet. Many proposed ICN hop-by-hop congestion control schemes assume a fixed and known link capacity, which rarely - if ever - holds true for wireless links. Firstly, we demonstrate that although these congestion control schemes are able to fairly well utilise the available wireless link capacity, they greatly fail to keep the delay low. In fact, they essentially offer the same delay as in the case with no hop-by-hop, only end-to-end, congestion control. Secondly, we show that by complementing these schemes with an easy-to-implement, packet-train capacity estimator, we reduce the delay to a level significantly lower than what is obtained with only end-to-end congestion control, while still being able to keep the link utilisation at a high level.

  • 173.
    Ahlgren, Bengt
    et al.
    RISE, Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    Jonasson, Arndt
    RISE, Swedish ICT, SICS, Software and Systems Engineering Laboratory.
    Scalable Live TV Distribution with NetInf to Android Devices (poster/demo)2014Conference paper (Refereed)
  • 174.
    Ahlgren, Bengt
    et al.
    RISE, Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    Jonasson, Arndt
    RISE, Swedish ICT, SICS, Software and Systems Engineering Laboratory.
    Ohlman, Börje
    Ericsson AB, Sweden.
    HTTP Live Streaming over NetInf Transport2014Conference paper (Refereed)
    Abstract [en]

    We modified a commercial Android TV app to use NetInf ICN transport. It was straightforward to adapt the standard HTTP Live Streaming to NetInf naming and network service. We demonstrate that NetInf's in-network caching and request aggregation result in efficient live TV distribution.

  • 175.
    Ahlgren, Bengt
    et al.
    RISE, Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    Karl, Holger
    Kutscher, Dirk
    Zhang, Lixia
    Special section on Information-Centric Networking (editorial)2013In: Computer Communications, ISSN 0140-3664, E-ISSN 1873-703X, Vol. 36Article in journal (Refereed)
  • 176.
    Ahlgren, Bengt
    et al.
    RISE, Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    Lindgren, Anders
    RISE, Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    Wu, Yanqiu
    RISE, Swedish ICT, SICS. KTH Royal Institute of Technology, Sweden.
    Demo: Experimental Feasibility Study of CCN-lite on Contiki Motes for IoT Data Streams2016In: Proceedings of the 3rd ACM Conference on Information-Centric Networking, 2016, p. 221-222Conference paper (Refereed)
    Abstract [en]

    Many IoT applications are inherently information-centric, making it advantageous to use ICN transport. We demonstrate CCN-lite ported to run on Contiki sensor motes with limited processing and storage resources. We show a method for mapping streams of sensor data to a stream of immutable CCN named data objects, and an adaptive probing method to find the newest value. We also demonstrate interoperation between MQTT and CCN via a gateway. A higher level goal is to use ICN as an open interface for accessing IoT data.

  • 177.
    Ahlgren, Bengt
    et al.
    RISE, Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    Lindgren, Per
    Sirotkin, Teet
    SPION: Secure Protocols in OSI Networks1989Report (Other academic)
    Abstract [en]

    SPION: Secure Protocols in OSI Networks This report describes how security services can be realized in a computer network using the protocols of the Open Systems Interconnection (OSI) reference model for communication. The report starts with defining security requirements for a "typical" local area network in a company, university or similar organization. It is assumed that the organization does not use the network for transfer of extremely sensitive information, such as military secrets. A set of security services, as specified in the OSI security architecture, are selected in order to satisfy the requirements. The selected services are then placed in suitable layers of the OSI model according to the criteria in the security architecture, and to the taste of the authors. The report concentrates on the transport layer. An extension of the OSI transport protocol, class 4, including security services is described in detail. The protocol is a fully compatible extension of the standard transport protocol. Key management is another topic which is included in the report. A key management system for handling public keys and digital signatures based on an article by Dorothy E. Denning is described. The system includes functions for distributing and validating public keys, and registering and later verifying digital signatures. A key management protocol supporting these functions is defined for communication between ordinary open systems and special key server systems.

  • 178.
    Ahlgren, Bengt
    et al.
    RISE, Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    Lindgren, Per
    Sirotkin, Teet
    State of the art in network security1990Report (Other academic)
    Abstract [en]

    This report is an effort to describe the state-of-the-art in computer network security focusing on the OSI Security architecture. Other sources of information include the NCSC "Trusted Network Interpretation of the TCSEC". The report describes the security threats imposed on networks and the countermeasures available. It gives a detailed description of the security services defined in the OSI Security architecture and the mechanisms proposed for realizing these services. An overview of security management with emphasis on key management is also included. The report contains numerous references to books and articles in the field of network security.

  • 179.
    Ahlgren, Bengt
    et al.
    RISE, Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    Ohlman, Börje
    Axelsson, Erik
    Brown, Lars
    Experiments with Subversion Over OpenNetInf and CCNx2011Conference paper (Refereed)
    Abstract [en]

    We describe experiences and insights from adapting the Subversion version control system to use the network service of two information-centric networking (ICN) prototypes: OpenNetInf and CCNx. The evaluation is done using a local collaboration scenario, common in our own project work where a group of people meet and share documents through a Subversion repository. The measurements show a performance benefit already with two clients in some of the studied scenarios, despite being done on un-optimised research prototypes. The conclusion is that ICN clearly is beneficial also for non mass-distribution applications.

  • 180.
    Ahlgren, Bengt
    et al.
    RISE, Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    Ohlman, Börje
    Axelsson, Erik
    Brown, Lars
    Subversion Over OpenNetInf and CCNx2011Conference paper (Refereed)
    Abstract [en]

    We describe experiences and insights from adapting the Subversion version control system to use the network service of two information-centric networking (ICN) prototypes: OpenNetInf and CCNx. The evaluation is done using a local collaboration scenario, common in our own project work where a group of people meet and share documents through a Subversion repository. The measurements show a performance benefit already with two clients in some of the studied scenarios, despite being done on un-optimised research prototypes. The conclusion is that ICN clearly is beneficial also for non mass-distribution applications. It was straightforward to adapt Subversion to fetch updated files from the repository using the ICN network service. The adaptation however neglected access control which will need a different approach in ICN than an authenticated SSL tunnel. Another insight from the experiments is that care needs to be taken when implementing the heavy ICN hash and signature calculations. In the prototypes, these are done serially, but we see an opportunity for parallelisation, making use of current multi-core processors.

  • 181.
    Ahlgren, Bengt
    et al.
    RISE, Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    Ohlman, Börje
    Malik, Adeel Mohammad
    NetInf Live Video Specification2015Other (Other academic)
    Abstract [en]

    This document specifies how the NetInf information-centric network service can be used for transport of live video streaming. To illustrate this it describes a prototype system that was developed to be used at "events with large crowds", e.g., sports events. The specification defines how the used video format is mapped to NetInf named data objects (NDOs). It also describe how NetInf messages are used to transfer the NDOs.

  • 182.
    Ahlgren, Bengt
    et al.
    RISE, Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    Pink, Stephen
    RISE, Swedish ICT, SICS.
    Gunningberg, Per
    RISE, Swedish ICT, SICS.
    A Host Interface to the DTM Network1992Report (Other academic)
    Abstract [en]

    DTM, dynamic synchronous transfer mode, is a new time division multiplexing technique for fiber networks currently being developed and implemented at the Royal Institute of Technology in Stockholm, Sweden. This paper describes the hardware and software aspects of the design of an SBus host interface to the DTM network for a Sun SPARCstation. The interface is based on a dual port memory residing on the interface card and accesible over the SBus from the host CPU. The host operating system allocates message buffers directly in this memory. The interface has hardware support for segmenting and reassembling packets to and from the data units of the DTM. The software part of the interface manages the shared memory and the virtual circuits provided by the DTM network.

  • 183.
    Ahlgren, Bengt
    et al.
    RISE, Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    Vercellone, Vinicio
    Networking of Information – An information-centric approach to the network of the future2010Conference paper (Refereed)
  • 184. Ahlgren, M.
    et al.
    Gustafsson, I.-B.
    Hall, Gunnar
    SIK – Institutet för livsmedel och bioteknik.
    Attitudes and beliefs directed towards ready meal consumption.2004In: Food Service Technology, Vol. 4, no 4, p. 159-169Article in journal (Refereed)
  • 185. Ahlgren, M.
    et al.
    Gustafsson, I.-B.
    Hall, Gunnar
    SIK – Institutet för livsmedel och bioteknik.
    Buyers' demands for ready meals: Influenced by gender and who will eat them.2006In: Journal of Foodservice, Vol. 7, p. 205-211Article in journal (Refereed)
  • 186. Ahlgren, M.
    et al.
    Gustafsson, I.-B.
    Hall, Gunnar
    SIK – Institutet för livsmedel och bioteknik.
    The impact of the meal situation on the consumption of ready meals.2005In: International Journal of Consumer Studies, Vol. 29, p. 485-492Article in journal (Refereed)
  • 187.
    Ahlgren, Mia
    SIK – Institutet för livsmedel och bioteknik.
    Ready meal consumption - when, where, why and by whom?2004Report (Other academic)
  • 188.
    Ahlgren, S
    SIK – Institutet för livsmedel och bioteknik.
    Environmental impact of chemical and mechanical weed control in agriculture : a comparing study using Life Cycle Assessment (LCA) methodology2004Report (Other academic)
  • 189. Ahlgren, S.
    et al.
    Baky, Andras
    RISE, SP – Sveriges Tekniska Forskningsinstitut, JTI Institutet för Jordbruks- och Miljöteknik.
    Bernesson, S.
    Nordberg, Åke
    RISE, SP – Sveriges Tekniska Forskningsinstitut, JTI Institutet för Jordbruks- och Miljöteknik.
    Norén, Olle
    RISE, SP – Sveriges Tekniska Forskningsinstitut, JTI Institutet för Jordbruks- och Miljöteknik.
    Hansson, P.-A.
    Ammonium nitrate fertiliser production based on biomass: Environmental effects from a life cycle perspective2008In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 99, no 17, p. 8034-8041Article in journal (Refereed)
    Abstract [en]

    Ammonium nitrate and calcium ammonium nitrate are the most commonly used straight nitrogen fertilisers in Europe, accounting for 43% of the total nitrogen used for fertilisers. They are both produced in a similar way; carbonate can be added as a last step to produce calcium ammonium nitrate. The environmental impact, fossil energy input and land use from using gasified biomass (cereal straw and short rotation willow (Salix) coppice) as feedstock in ammonium nitrate production were studied in a cradle-to-gate evaluation using life cycle assessment methodology. The global warming potential in the biomass systems was only 22-30% of the impact from conventional production using natural gas. The eutrophication potential was higher for the biomass systems due to nutrient leaching during cultivation, while the acidification was about the same in all systems. The primary fossil energy use was calculated to be 1.45 and 1.37 MJ/kg nitrogen for Salix and straw, respectively, compared to 35.14 MJ for natural gas. The biomass production was assumed to be self-supporting with nutrients by returning part of the ammonium nitrate produced together with the ash from the gasification. For the production of nitrogen from Salix, it was calculated that 3914 kg of nitrogen can be produced every year from 1 ha, after that 1.6% of the produced nitrogen has been returned to the Salix production. From wheat straw, 1615 kg of nitrogen can be produced annually from 1 ha, after that 0.6% of the nitrogen has been returned. © 2008 Elsevier Ltd. All rights reserved.

  • 190. Ahlgren, S.
    et al.
    Baky, Andras
    RISE, SP – Sveriges Tekniska Forskningsinstitut, JTI Institutet för Jordbruks- och Miljöteknik.
    Bernesson, S.
    Nordberg, Åke
    RISE, SP – Sveriges Tekniska Forskningsinstitut, JTI Institutet för Jordbruks- och Miljöteknik.
    Norén, Olle
    RISE, SP – Sveriges Tekniska Forskningsinstitut, JTI Institutet för Jordbruks- och Miljöteknik.
    Hansson, P.-A.
    Future fuel supply systems for organic production based on Fischer-Tropsch diesel and dimethyl ether from on-farm-grown biomass2008In: Biosystems Engineering, ISSN 1537-5110, E-ISSN 1537-5129, Vol. 99, no 1, p. 145-155Article in journal (Refereed)
    Abstract [en]

    The effects of making a 1000 ha organic farm self-sufficient in renewable fuel were studied. Biomass grown on-farm can be transported to large fuel production facilities and the fuel transported back to the farm. Two fuels, Fischer-Tropsch diesel (FTD) and dimethyl ether (DME), produced from either straw or short-rotation willow coppice (Salix), were studied. The environmental impact, land use and energy balance were calculated using life-cycle methodology. It was calculated that the straw-based systems had only 32-39% of the impact on global warming (kg [CO2-eq]) compared to the Salix-based systems. For acidification and eutrophication, the differences between the systems were less significant. The energy balances were 8.9 and 9.6 for FTD and 10.1 and 10.0 for DME, from straw and Salix, respectively. To become self-sufficient in FTD, 108 ha has to be set aside for Salix production or 261 ha of straw collected from the existing crop rotation. For DME the corresponding figures are 38 and 70 ha. The many by-products in the FTD scenarios explain the large difference between fuels. Comparing FTD and DME, the differences in environmental impact were small. Considering this, FTD is a more likely alternative since DME requires a pressurised infrastructure system and engine modifications. © 2007 IAgrE.

  • 191. Ahlgren, S.
    et al.
    Baky, Andras
    RISE, SP – Sveriges Tekniska Forskningsinstitut, JTI Institutet för Jordbruks- och Miljöteknik.
    Bernesson, S.
    Nordberg, Åke
    RISE, SP – Sveriges Tekniska Forskningsinstitut, JTI Institutet för Jordbruks- och Miljöteknik.
    Norén, Olle
    RISE, SP – Sveriges Tekniska Forskningsinstitut, JTI Institutet för Jordbruks- och Miljöteknik.
    Hansson, P.-A.
    Tractive power in organic farming based on fuel cell technology: Energy balance and environmental load2009In: Agricultural Systems, ISSN 0308-521X, E-ISSN 1873-2267, Vol. 102, no 1-3, p. 67-76Article in journal (Refereed)
    Abstract [en]

    This study analysed a future hypothetical organic farm self-sufficient in renewable tractor fuel. Biomass from the farm was assumed to be transported to a central fuel production plant and the fuel returned to the farm, where it was utilised in fuel cell powered tractors. The land use, energy balance and environmental impact of five different scenarios were studied. In the first two scenarios, straw was used as raw material for production of hydrogen or methanol via thermochemical gasification. In the third and fourth scenarios, short rotation forest (Salix) was used as raw material for the same fuels. In the fifth scenario, ley was used as raw material for hydrogen fuel via biogas production. The straw scenarios had the lowest impact in all studied environmental impact categories since the Salix scenarios had higher soil emissions and the ley scenario had comparatively large emissions from the fuel production. The energy balance was also favourable for straw, 16.3 and 19.5 for hydrogen and methanol respectively, compared to Salix 14.2 and 15.6. For ley to hydrogen the energy balance was only 6.1 due to low efficiency in the fuel production. In the Salix scenarios, 1.6% and 2.0% of the land was set aside for raw material production in the hydrogen and methanol scenarios respectively. In the straw scenarios no land needed to be reserved, but straw was collected on 4.3% and 5.3% of the area for hydrogen and methanol respectively. To produce hydrogen from ley, 4% of the land was harvested. The study showed that the difference in environmental performance lay in choice of raw material rather than choice of fuel. Hydrogen is a gas with low volumetric energy density, which requires an adapted infrastructure and tractors equipped with gas tanks. This leads to the conclusion that methanol probably will be the preferred choice if a fuel cell powered farm would be put into practice in the future. © 2009 Elsevier Ltd. All rights reserved.

  • 192. Ahlgren, S.
    et al.
    Bernesson, S.
    Nordberg, Åke
    RISE, SP – Sveriges Tekniska Forskningsinstitut, JTI Institutet för Jordbruks- och Miljöteknik.
    Hansson, P-A.
    Nitrogen fertiliser production based on biogas: Energy input, environmental impact and land use.2010In: Bioresource Technology, Vol. 101, p. 7192-7195Article in journal (Refereed)
  • 193. Ahlgren, Serina
    et al.
    Baky, Andras
    RISE, SP – Sveriges Tekniska Forskningsinstitut, JTI Institutet för Jordbruks- och Miljöteknik.
    Bernesson, Sven
    Nordberg, Åke
    RISE, SP – Sveriges Tekniska Forskningsinstitut, JTI Institutet för Jordbruks- och Miljöteknik.
    Det svenska jordbrukets framtida drivmedelsförsörjning2010Report (Refereed)
  • 194. Ahlgren, Serina
    et al.
    Baky, Andras
    RISE, SP – Sveriges Tekniska Forskningsinstitut, JTI Institutet för Jordbruks- och Miljöteknik.
    Bernesson, Sven
    Nordberg, Åke
    RISE, SP – Sveriges Tekniska Forskningsinstitut, JTI Institutet för Jordbruks- och Miljöteknik.
    Green nitrogen2011Report (Refereed)
  • 195. Ahlgren, Serina
    et al.
    Baky, Andras
    RISE, SP – Sveriges Tekniska Forskningsinstitut, JTI Institutet för Jordbruks- och Miljöteknik.
    Bernesson, Sven
    Nordberg, Åke
    RISE, SP – Sveriges Tekniska Forskningsinstitut, JTI Institutet för Jordbruks- och Miljöteknik.
    Norén, Olle
    RISE, SP – Sveriges Tekniska Forskningsinstitut, JTI Institutet för Jordbruks- och Miljöteknik.
    Hansson, Per-Anders
    Consequential life cycle assessment of nitrogen fertilisers based on biomass: A Swedish perspective.2012In: Insciences Journal Climate Change, Vol. 2, no 4, p. 80-101Article in journal (Refereed)
  • 196.
    Ahlgren, Serina
    et al.
    SLU Swedish University of Agricultural Sciences, Sweden.
    Björklund, Anna
    KTH Royal Institute of Technology, Sweden.
    Ekman, Anna
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Food and Bioscience, Environment. Lund University, Sweden.
    Karlsson, Hanna
    SLU Swedish University of Agricultural Sciences, Sweden.
    Berlin, Johanna
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energi och Bioekonomi, Systemanalys.
    Börjesson, Pål
    Lund University, Sweden.
    Ekvall, Tomas
    IVL Swedish Environmental Research Institute, Sweden.
    Finnveden, Göran
    KTH Royal Institute of Technology, Sweden.
    Janssen, Matty
    Chalmers University of Technology, Sweden.
    Strid, Ingrid
    SLU Swedish University of Agricultural Sciences, Sweden.
    Review of methodological choices in LCA of biorefinery systems - key issues and recommendations2015In: Biofuels, Bioproducts and Biorefining, ISSN 1932-104X, E-ISSN 1932-1031, Vol. 9, no 5, p. 606-619Article in journal (Refereed)
    Abstract [en]

    The current trend in biomass conversion technologies is toward more efficient utilization of biomass feedstock in multiproduct biorefineries. Many life-cycle assessment (LCA) studies of biorefinery systems have been performed but differ in how they use the LCA methodology. Based on a review of existing LCA standards and guidelines, this paper provides recommendations on how to handle key methodological issues when performing LCA studies of biorefinery systems. Six key issues were identified: (i) goal definition, (ii) functional unit, (iii) allocation of biorefinery outputs, (iv) allocation of biomass feedstock, (v) land use, and (vi) biogenic carbon and timing of emissions. Many of the standards and guidelines reviewed here provide only general methodological recommendations. Some make more specific methodological recommendations, but these often differ between standards. In this paper we present some clarifications (e.g. examples of research questions and suitable functional units) and methodological recommendations (e.g. on allocation).

  • 197. Ahlqvist, J.
    et al.
    Dainiak, M.B.
    Kumar, A.
    Hornsten, Gunnar E.
    Galaev, I.Yu.
    Mattiasson, B.
    Monitoring the production of inclusion bodies during fermentation and enzyme-linked immunosorbent assay analysis of intact inclusion bodies using cryogel minicolumn plates2006In: Analytical Biochemistry, ISSN 0003-2697, E-ISSN 1096-0309, Vol. 354, no 2, p. 229-237Article in journal (Refereed)
    Abstract [en]

    A novel minicolumn chromatographic method to monitor the production of inclusion bodies during fermentation and an enzyme-linked immunosorbent assay (ELISA) system allowing direct analysis of the particles with surface-displayed antigens are described. A 33-kDa protein containing 306 amino acids with three sulfur bridges produced as inclusion bodies was labeled with polyclonal antibodies against 15 amino acid (anti-A15) and 17 amino acid (anti-B17) residues at the N- and C-terminal ends of the protein, respectively. Labeled particles were bound to macroporous monolithic protein A-cryogel adsorbents inserted into the open-ended wells of a 96-well plate (referred to as protein A-cryogel minicolumn plate). The concept behind this application is that the binding degree of inclusion bodies from lysed fermentation broth to the cryogel minicolumns increases with an increase in their concentration during fermentation. The technique allowed us to monitor the increase in the production levels of the inclusion bodies as the fermentation process progressed. The system also has a built-in quality parameter to ensure that the target protein has been fully expressed. Alternatively, inclusion bodies immobilized on phenyl-cryogel minicolumn plate were used in indirect ELISA based on anti-A15 and anti-B17 antibodies against terminal amino acid residues displayed on the surface of inclusion bodies. Drainage-protected properties of the cryogel minicolumns allow performance of successive reactions with tested immunoglobulin G (IgG) samples and enzyme-conjugated secondary IgG and of enzymatic reaction within the adsorbent. © 2006 Elsevier Inc. All rights reserved.

  • 198. Ahlqvist, J.
    et al.
    Kumar, A.
    Sundstrom, H.
    Ledung, E.
    Hornsten, E.G.
    Enfors, S.-O.
    Affinity binding of inclusion bodies on supermacroporous monolithic cryogels using labeling with specific antibodies2006In: Journal of Biotechnology, ISSN 0168-1656, E-ISSN 1873-4863, Vol. 122, no 2, p. 216-225Article in journal (Refereed)
    Abstract [en]

    A new chromatographic method based on affinity supermacroporous monolithic cryogels is developed for binding and analyzing inclusion bodies during fermentation. The work demonstrated that it is possible to bind specific IgG and IgY antibodies to the 15 and 17 amino acids at the terminus ends of a 33 kDa target protein aggregated as inclusion bodies. The antibody treated inclusion bodies from lysed fermentation broth can be specifically retained in protein A and pseudo-biospecific ligand sulfamethazine modified supermacroporous cryogels. The degree of binding of IgG and IgY treated inclusion bodies to the Protein A and sulfamethazine gels are investigated, as well as the influence of pH on the sulfamethazine ligand. Optimum binding of 78 and 72% was observed on both protein A and sulfamethazine modified cryogel columns, respectively, using IgG labeling of the inclusion bodies. The antibody treated inclusion bodies pass through unretained in the sulfamethazine supermacroporous gel at pH that does not favour the binding between the ligand on the gel and the antibodies on the surface of inclusion bodies. Also the unlabeled inclusion bodies went through the gel unretained, showing no non-specific binding or trapping within the gel. These findings may very well be the foundation for the building of a powerful analytical tool during fermentation of inclusion bodies as well as a convenient way to purify them from fermentation broth. These results also support our earlier findings [Kumar, A., Plieva, F.M., Galaev, I.Yu., Mattiasson, B., 2003. Affinity fractionation of lymphocytes using a monolithic cyogel. J. Immunol. Methods 283, 185-194] with mammalian cells that were surface labeled with specific antibodies and recognized on protein A supermacroporous gels. A general binding and separation system can be established on antibody binding cryogel affinity matrices. © 2005 Elsevier B.V. All rights reserved.

  • 199.
    Ahlqvist, Josefin
    SIK – Institutet för livsmedel och bioteknik.
    Using monolithic cryogels for direct capture of inclusion bodies during fermentation - a way to monitor the process2006Report (Refereed)
  • 200.
    Ahlqvist, Josefin
    SIK – Institutet för livsmedel och bioteknik.
    Using monolithic cryogels for direct capture of inclusion bodies during fermentation - a way to monitor the process2006Report (Other academic)
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