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Lennerstad, Håkan
Publications (10 of 61) Show all publications
Lundberg, L., Lennerstad, H., Boeva, V. & García Martín, E. (2019). Handling non-linear relations in support vector machines through hyperplane folding. In: ACM International Conference Proceeding Series: . Paper presented at 11th International Conference on Machine Learning and Computing, ICMLC 2019; Zhuhai; China; 22 February 2019 through 24 February (pp. 137-141). Association for Computing Machinery
Open this publication in new window or tab >>Handling non-linear relations in support vector machines through hyperplane folding
2019 (English)In: ACM International Conference Proceeding Series, Association for Computing Machinery , 2019, p. 137-141Conference paper, Published paper (Refereed)
Abstract [en]

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 half of the shortest distance between any pair of data points from the two different classes. We provide an algorithm for the general case with n-dimensional data points. A small experiment with three folding iterations on 3-dimensional data points with non-linear relations shows that the margin does indeed increase and that the accuracy improves with a larger margin. The method can use any standard SVM implementation plus some basic manipulation of the data points, i.e., splitting, rotating and merging. Hyperplane folding also increases the interpretability of the data. © 2019 Association for Computing Machinery.

Place, publisher, year, edition, pages
Association for Computing Machinery, 2019
Keywords
Hyperplane folding, Hyperplane hinging, Non-linear relations, Piecewise linear classification, Support vector machines, Geometry, Piecewise linear techniques, Vectors, Different class, Interpretability, Nonlinear relations, Piecewise linear, Support vector, Support vector machine (SVMs)
National Category
Computer Sciences
Identifiers
urn:nbn:se:bth-18039 (URN)10.1145/3318299.3318319 (DOI)000477981500023 ()2-s2.0-85066460409 (Scopus ID)
Conference
11th International Conference on Machine Learning and Computing, ICMLC 2019; Zhuhai; China; 22 February 2019 through 24 February
Available from: 2019-06-14 Created: 2019-06-14 Last updated: 2019-09-10Bibliographically approved
Lennerstad, H. (2019). The n -dimensional Stern-Brocot tree. International Journal of Number Theory, 15(6), 1219-1236
Open this publication in new window or tab >>The n -dimensional Stern-Brocot tree
2019 (English)In: International Journal of Number Theory, ISSN 1793-0421, Vol. 15, no 6, p. 1219-1236Article in journal (Refereed) Published
Abstract [en]

This paper generalizes the Stern-Brocot tree to a tree that consists of all sequences of n coprime positive integers. As for n = 2, each sequence P is the sum of a specific set of other coprime sequences, its Stern-Brocot set B(P), where |B(P)| is the degree of P. With an orthonormal base as the root, the tree defines a fast iterative structure on the set of distinct directions in ℤ+n and a multiresolution partition of S+n-1. Basic proofs rely on a matrix representation of each coprime sequence, where the Stern-Brocot set forms the matrix columns. This induces a finitely generated submonoid SB(n, ℕ) of SL(n, ℕ), and a unimodular multidimensional continued fraction algorithm, also generalizing n = 2. It turns out that the n-dimensional subtree starting with a sequence P is isomorphic to the entire |B(P)|-dimensional tree. This allows basic combinatorial properties to be established. It turns out that also in this multidimensional version, Fibonacci-type sequences have maximal sequence sum in each generation. © 2019 World Scientific Publishing Company.

Place, publisher, year, edition, pages
World Scientific Publishing Co. Pte Ltd, 2019
Keywords
coprimality, matrix representation, multidimensional continued fraction, S L (n, ℕ), Stern-Brocot tree
National Category
Geometry Mathematical Analysis
Identifiers
urn:nbn:se:bth-17772 (URN)10.1142/S1793042119500672 (DOI)000476732000007 ()2-s2.0-85062921934 (Scopus ID)
Available from: 2019-04-05 Created: 2019-04-05 Last updated: 2019-09-10Bibliographically approved
Sidorova, Y., Sköld, L., Lennerstad, H. & Lundberg, L. (2019). The Use of Fuzzy Logic in Creating a Visual Data Summary of a Telecom Operator’s Customer Base. In: Communications in Computer and Information Science: . Paper presented at 1st International Conference on Intelligent Technologies and Applications, INTAP 2018; Bahawalpur; Pakistan; 23 October 2018 through 25 October 2018 (pp. 301-312). Springer Verlag, 932
Open this publication in new window or tab >>The Use of Fuzzy Logic in Creating a Visual Data Summary of a Telecom Operator’s Customer Base
2019 (English)In: Communications in Computer and Information Science, Springer Verlag , 2019, Vol. 932, p. 301-312Conference paper, Published paper (Refereed)
Abstract [en]

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 presence in different neighborhoods and regions. The data used for validation cover historical mobility in a region of Sweden during a week. Fuzzy logic allows us to model inherently relative characteristics, such as “a tall man” or “a beautiful woman”, and importantly it also defines “anchors”, the situations (characterized with the value of the membership function for the characteristic) under which the relative notion receives a unique crisp interpretation. We propose color coding of the membership value for the relative notions such as “the desirability of boosting operator’s presence in the neighborhood” and “how well the operator is doing in the region”. The corresponding regions on the map (e.g., postcode zones or larger groupings) are colored in different shades passing from green (1) though yellow (0.5) to red (0). The color hues pass a clear intuitive message making the summary easy to grasp. © 2019, Springer Nature Singapore Pte Ltd.

Place, publisher, year, edition, pages
Springer Verlag, 2019
Series
Communications in Computer and Information Science, ISSN 1865-0929 ; 932
Keywords
Call Detail Records, Color, Fuzzy membership function, Mobility data, Computer circuits, Decision making, Fuzzy set theory, Membership functions, Color coding, Customerbase, Membership values, Mobility datum, Telecom operators, Use of fuzzy logic, Fuzzy logic
National Category
Telecommunications
Identifiers
urn:nbn:se:bth-17870 (URN)10.1007/978-981-13-6052-7_26 (DOI)000465006200026 ()9789811360510 (ISBN)
Conference
1st International Conference on Intelligent Technologies and Applications, INTAP 2018; Bahawalpur; Pakistan; 23 October 2018 through 25 October 2018
Available from: 2019-05-02 Created: 2019-05-02 Last updated: 2019-05-03Bibliographically approved
Lennerstad, H. & Eriksson, M. (2018). List graphs and distance-consistent node labelings. Electronic Journal of Graph Theory and Applications, 6(1), 152-165
Open this publication in new window or tab >>List graphs and distance-consistent node labelings
2018 (English)In: Electronic Journal of Graph Theory and Applications, ISSN 2338-2287, Vol. 6, no 1, p. 152-165Article in journal (Refereed) Published
Abstract [en]

In this paper we consider node labelings c of an undirected connected graph G = (V,E) with labels (1, 2, ...,|V|), which induce a list distance c(u, v) = |c(v) - c(u)| besides the usual graph distance d(u, v). Our main aim is to find a labeling c so c(u; v) is as close to d(u, v) as possible. For any graph we specify algorithms to find a distance-consistent labeling, which is a labeling c that minimize Σ u,vεV (c(u, v) - d(u, v))2. Such labeliings may provide structure for very large graphs. Furthermore, we define a labeling c fulfilling d(u1, v1) < d(u2, v2) ) c(u1, v1) ⇒ c(u2, v2) for all node pairs u1; v1 and u2; v2 as a list labeling, and a graph that has a list labeling is a list graph. We prove that list graphs exist for all n = |V| and all k = |E|: n - 1 ≤ k ≤ n(n - 1)/2, and establish basic properties. List graphs are Hamiltonian, and show weak versions of properties of path graphs. © 2018 Indonesian Combinatorics Society.

Place, publisher, year, edition, pages
INST TEKNOLOGI BANDUNG, 2018
Keywords
Extremal combinatorics, Graph distance, Graph labeling
National Category
Mathematics
Identifiers
urn:nbn:se:bth-16110 (URN)10.5614/ejgta.2018.6.1.11 (DOI)000437328400011 ()2-s2.0-85045005282 (Scopus ID)
Available from: 2018-04-19 Created: 2018-04-19 Last updated: 2018-08-20Bibliographically approved
Laksman, E., Lennerstad, H. & Nilsson, M. (2015). Generalized upper bounds on the minimum distance of PSK block codes. IMA Journal of Mathematical Control and Information, 32(2), 305-327
Open this publication in new window or tab >>Generalized upper bounds on the minimum distance of PSK block codes
2015 (English)In: IMA Journal of Mathematical Control and Information, ISSN 0265-0754, E-ISSN 1471-6887, Vol. 32, no 2, p. 305-327Article, review/survey (Refereed) Published
Abstract [en]

This paper generalizes previous optimal upper bounds on the minimum Euclidean distance for phase shift keying (PSK) block codes, that are explicit in three parameters: alphabet size, block length and code size. The bounds are primarily generalized from codes over symmetric PSK to codes over asymmetric PSK and also to general alphabet size. Furthermore, block codes are optimized in the presence of other types of noise than Gaussian, which induces also non-Euclidean distance measures. In some instances, codes over asymmetric PSK prove to give higher Euclidean distance than any code over symmetric PSK with the same parameters. We also provide certain classes of codes that are optimal among codes over symmetric PSK.

Abstract [sv]

Detta papper generaliserar tidigare optimala övre gränser för minimala Euklidiska avståndet för fasskift block koder, s.k. phase shift keying (PSK). De är explicita i tre parametrar: alfabetstorlek, blocklängd och kodstorlek. Gränserna är framförallt generaliserade från koder över symmetrisk PSK till koder över asymmetrisk PSK men även till generell alfabetsstorlek. Block koder är även generaliserade i närvaro av annat brus än gaussiskt, vilket leder till icke-Euklidiska avståndsmått. I vissa fall ger asymmetrisk PSK högre Euklidiskt avstånd än symmetriskt med samma parametrar. Vi visar också att vissa kodklasser är optimala i gruppen av symmetrisk PSK.

Place, publisher, year, edition, pages
Oxford Journals, 2015
Keywords
Assymetric PSK, symmetric PSK, Elias' bound.
National Category
Mathematical Analysis Telecommunications
Identifiers
urn:nbn:se:bth-6608 (URN)10.1093/imamci/dnt047 (DOI)000358779200006 ()oai:bth.se:forskinfo7520A9E3949B10C1C1257D630059B28A (Local ID)oai:bth.se:forskinfo7520A9E3949B10C1C1257D630059B28A (Archive number)oai:bth.se:forskinfo7520A9E3949B10C1C1257D630059B28A (OAI)
Note

Open access article

Available from: 2014-10-03 Created: 2014-09-30 Last updated: 2017-12-04Bibliographically approved
Niyizamwiyitira, C., Lundberg, L. & Lennerstad, H. (2015). Utilization-Based Schedulability Test of Real-Time Systems on Virtual Multiprocessors. In: 2015 44TH INTERNATIONAL CONFERENCE ON PARALLEL PROCESSING WORKSHOPS: . Paper presented at 44th Annual Conference of the International Conference on Parallel Processing Workshops, (ICPPW), Beijing (pp. 267-276). IEEE Computer Society, 2015-January
Open this publication in new window or tab >>Utilization-Based Schedulability Test of Real-Time Systems on Virtual Multiprocessors
2015 (English)In: 2015 44TH INTERNATIONAL CONFERENCE ON PARALLEL PROCESSING WORKSHOPS, IEEE Computer Society, 2015, Vol. 2015-January, p. 267-276Conference paper, Published paper (Refereed)
Abstract [en]

The number of applications that use virtual systems is growing, and one would like to use this kind of systems also for real-time applications with hard deadlines. Virtual machines with many cores are interesting since the underlying physical infrastructure usually contains many cores. We consider hard real-time tasks that execute on a virtual machine with m cores. Tasks are scheduled globally on the cores using fixed-priority preemptive scheduling. This means that a task can execute on different virtual cores at different instances in time. In order to avoid Dhall’s effect, which may cause task sets with even very low utilization to miss deadlines, we classify tasks into two priority classes, namely heavy and light tasks. Heavy tasks have higher priority than light tasks. For light tasks we use rate monotonic priority assignment. In this paper we propose a utilization-based test that shows if a task set is schedulable or not. If the task set is schedulable the test provides the priority for each task. The input to the test is the task set, the number of cores in the virtual machine (m), a period for the virtual machine with m cores, and the blocking time when a virtual machine does not have access to the underlying hardware in each period. © 2015 IEEE.

Place, publisher, year, edition, pages
IEEE Computer Society, 2015
Series
International Conference on Parallel Processing Workshops, ISSN 1530-2016
Keywords
Interactive computer systems; Java programming language; Multiprocessing systems; Scheduling; Testing, Fixed priority preemptive; Fixed priority scheduling; Hard real-time; Hard real-time task; Multi processor scheduling; Priority assignment; Real-time application; Utilization based tests, Real time systems
National Category
Computer and Information Sciences
Identifiers
urn:nbn:se:bth-11582 (URN)10.1109/ICPPW.2015.27 (DOI)000377378800034 ()2-s2.0-84954511253 (Scopus ID)9781467375894 (ISBN)
Conference
44th Annual Conference of the International Conference on Parallel Processing Workshops, (ICPPW), Beijing
Available from: 2016-02-03 Created: 2016-02-03 Last updated: 2018-01-10Bibliographically approved
Lennerstad, H. (2014). Local Linear Time Convergence of a Primal-Dual Energy Minimization Algorithm for Parallel Processing. In: : . Paper presented at 13th International Symposium on Parallel and Distributed Computing (ISPDC), Marseille. IEEE
Open this publication in new window or tab >>Local Linear Time Convergence of a Primal-Dual Energy Minimization Algorithm for Parallel Processing
2014 (English)Conference paper, Published paper (Refereed)
Abstract [en]

We consider energy minimization by speed-scaling of an open shop multiprocessor with n jobs and m machines. The paper studies the complexity of a primal-dual solution algorithm of [4], which was an open question in that paper.We prove that in a neighbourhood of the solution the complexity of the algorithm is O(mn log(1/ε) if n and m are not equal and ε is the roundoff error of the computer. The paper demonstrates how linearization can be used to investigate the complexity of an algorithm close to the optimum. An estimate of the size of the neighbourhood where the linearization error is smaller than the computer’s roundoff error is also given.

Abstract [sv]

Pappret undersöker en energiminimiseringsalgoritm för en multiprocessor där processorns hastighet kan lokalt varieras för att minimera energin. För en open shop multiprocessor med n tasks och m maskiner studeras effektiviteten för en nyligen publicerad primal-dual algoritm. Nära optimium är dess komplexitet O(mn log(1/ε)) om n och m inte är lika och ε är datorns avrundningsfel. I pappret demonstreras hur linjarisering kan användas för att undersöka en algoritms komplexitet nära optimum. Vi visare också en uppskattning storleken för det område runt optimum där linjariseringsfelet är mindre än datorns avrundningsfel.

Place, publisher, year, edition, pages
IEEE, 2014
Series
International Symposium on Parallel and Distributed Computing, ISSN 2379-5352
Keywords
Open shop multiprocessor, Primal-dual algoritm, Speed-scaling, Complexity, Linearization.
National Category
Mathematical Analysis Computer Sciences
Identifiers
urn:nbn:se:bth-6413 (URN)10.1109/ISPDC.2014.21 (DOI)000360933900019 ()oai:bth.se:forskinfo3286C721500AD2A6C1257DF000334A06 (Local ID)978-1-4799-5918-1 (ISBN)oai:bth.se:forskinfo3286C721500AD2A6C1257DF000334A06 (Archive number)oai:bth.se:forskinfo3286C721500AD2A6C1257DF000334A06 (OAI)
Conference
13th International Symposium on Parallel and Distributed Computing (ISPDC), Marseille
Note

Published in proceedings of 2014 IEEE 13th International Symposium on Parallel and Distributed Computing (ISPDC), http://ieeexplore.ieee.org/xpl/mostRecentIssue.jsp?punumber=6898623

Available from: 2015-02-18 Created: 2015-02-18 Last updated: 2018-01-11Bibliographically approved
Laksman, E., Lennerstad, H. & Lundberg, L. (2012). Optimal computer crash performance precaution. Discrete Mathematics and Theoretical Computer Science, 14(1), 55-68
Open this publication in new window or tab >>Optimal computer crash performance precaution
2012 (English)In: Discrete Mathematics and Theoretical Computer Science, ISSN 1462-7264, Vol. 14, no 1, p. 55-68Article in journal (Refereed) Published
Abstract [en]

For a parallel computer system withmidentical 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 completion time of a parallel program after a crash is at most a factor r + 1 larger than if we use optimal allocation on m - 1 computers. This is an r-dependent restriction of the set of allocations of a program. Then, what is the worst-case ratio of the optimal r-dependent completion time in the case of no crash and the unrestricted optimal completion time of the same parallel program? We denote the maximal ratio of completion times f(r, m) - i.e., the ratio for worst-case programs. In the paper we establish upper and lower bounds of the worst-case cost function f(r, m) and characterize worst-case programs.

Place, publisher, year, edition, pages
Maison de l'informatique et des mathematiques discretes, 2012
Keywords
Computer crash, Load balancing, Optimization, Parallel computer, Process allocation, Scheduling
National Category
Mathematics Computer Sciences
Identifiers
urn:nbn:se:bth-7056 (URN)oai:bth.se:forskinfoB06EE51C5781B5C7C1257AC90038EBEF (Local ID)oai:bth.se:forskinfoB06EE51C5781B5C7C1257AC90038EBEF (Archive number)oai:bth.se:forskinfoB06EE51C5781B5C7C1257AC90038EBEF (OAI)
Note
Open Access JournalAvailable from: 2012-12-21 Created: 2012-12-03 Last updated: 2018-01-11Bibliographically approved
Lennerstad, H. (2012). The n-dimensional Stern-Brocot tree.
Open this publication in new window or tab >>The n-dimensional Stern-Brocot tree
2012 (English)Report (Other academic)
Alternative title[sv]
Stern-Brocots träd i n dimensioner
Abstract [en]

The n-dimensional Stern-Brocot tree consists of all sequences (p₁, ...,p_{n}) of positive integers with no common multiple. The relatively prime sequences can be generated branchwise from each other by simple vector summation, starting with an ON-base, and controlled by a generalized Euclidean algorithm.The tree induces a multiresolution partition of the first quadrant of the (n-1)-dimensional unit sphere, providing a direction approximation property of a sequence by its ancestors. Two matrix representations are introduced, where in both a matrix contains the parents of a sequence. From one of them the isomorphism of a subtree to the entire tree of dimension equal to the number of parents of the top sequence follows. A form of Fibonacci sequences turn out to be the sequences of fastest growing sums. The construction can be regarded an n-dimensional continued fraction, and it may invite further n-dimesional number theory.

Abstract [sv]

Stern-Brocots träd består av alla sekvenser (p₁, ...,p_{n}) av positiva heltal som saknar gemensam delare. De genereras gren för gren med vektoraddition, med en ON-bas som start, och kontrolleras av en generaliserad Euklidisk algoritm. Trädet inducerar en multiresolutionpartition av den första kvadranten av den (n-1)-dimensionella enhetssfären, vilket ger en riktningsapproximationsegenskap för en sekvens med dess föregångare i trädet. Två matrisrepresentationer presenteras, i båda innehåller matrisen alla föräldrar till en sekvens. Från en av dem följer isomorfismen av ett delträd med ett helt träd vars dimension är antalet föräldrar av toppsekvensen i delträdet. En typ av Fibonaccisekvenser visar sig vara sekvenserna som har snabbast växande summa. Konstruktionen kan ses som ett n-dimensionellt kedjebråk, och den kan vara en inbjudan till fortsatt n-dimensionell talteori. Nyckelord: Stern-Brocots träd, relativt prima tal, Fibonaccital, multiresolution partition, ON-bas, kedjebråk, Minkowskis frågeteckenfunktion.

Series
Blekinge Tekniska Högskola Forskningsrapport, ISSN 1103-1581 ; 4
Keywords
Stern-Brocot tree, relatively prime integers, relative primality, Fibonacci numbers, multiresolution partition, ON-base, continued fraction, Minkowski question mark function.
National Category
Mathematical Analysis Geometry
Identifiers
urn:nbn:se:bth-00534 (URN)oai:bth.se:forskinfoA02A252219018A4EC1257A16003CC993 (Local ID)oai:bth.se:forskinfoA02A252219018A4EC1257A16003CC993 (Archive number)oai:bth.se:forskinfoA02A252219018A4EC1257A16003CC993 (OAI)
External cooperation:
Available from: 2012-09-18 Created: 2012-06-07 Last updated: 2016-09-06Bibliographically approved
Lennerstad, H. & Olteanu, C. (2012). Åtta IKT-projekt för matematiken i skolan: empiri och analys.
Open this publication in new window or tab >>Åtta IKT-projekt för matematiken i skolan: empiri och analys
2012 (Swedish)Report (Other (popular science, discussion, etc.))
Alternative title[en]
Eight IKT-projects in school : empiry and analysis
Abstract [sv]

Denna rapport presenterar empiri och analys av en granskning av åtta projekt som mottagit medel från Skolverket för att tillämpa IKT i skolans matematikundervisning. Empirin är organiserad enligt aktivitetsteorin, vilken sätter relationerna mellan människa, miljö, aktiviteter och mål i förgrunden. Empirin som presenteras är till stor del sammanställda repliker från lärare och elever vid intervjuerna, organi¬sera¬de för att belysa verksamhetens olika relationer. Det betyder att presentationen är till stor del på de verksammas villkor, och på deras språk. Ett stort antal konkreta slutsatser framkommer ur detta material. En av dem är att klass¬upp-sätt¬ningar av datorer är sällan framgångsrika, på grund av att teknisk support ofta var otillräcklig, och att lärarna inte kan veta hur mycket eleverna använder datorerna till icke-skol-verk¬sam¬het. Dessa problem finns inte för interaktiva skrivtavlor. De framstår däremot som ett socialt verktyg, som gör utbyte och dialog om ämnet lättare att få till stånd. I flera fall framkom indirekt, men ändå tydligt, att utbildningen på tekniken hade varit otillräcklig, trots att lärarna inte uttryckte ett tydligt missnöje med den. Skrivtavlan ökade lärarnas motivation för samarbete. En framåtriktad slutsats är att en lärargrupp som har ett fungerande samarbete och goda didaktiska, ämnesmässiga, ledar- och relationella kompe¬tenser med en interaktiv skrivtavla har en möjlighet att komma längre med elevernas måluppfyllelse.

Abstract [en]

Denna rapport presenterar empiri och analys av en granskning av åtta projekt som mottagit medel från Skolverket för att tillämpa IKT i skolans matematikundervisning. Empirin är organiserad enligt aktivitetsteorin, vilken sätter relationerna mellan människa, miljö, aktiviteter och mål i förgrunden. Empirin som presenteras är till stor del sammanställda repliker från lärare och elever vid intervjuerna, organi¬sera¬de för att belysa verksamhetens olika relationer. Det betyder att presentationen är till stor del på de verksammas villkor, och på deras språk. Ett stort antal konkreta slutsatser framkommer ur detta material. En av dem är att klass¬upp-sätt¬ningar av datorer är sällan framgångsrika, på grund av att teknisk support ofta var otillräcklig, och att lärarna inte kan veta hur mycket eleverna använder datorerna till icke-skol-verk¬sam¬het. Dessa problem finns inte för interaktiva skrivtavlor. De framstår däremot som ett socialt verktyg, som gör utbyte och dialog om ämnet lättare att få till stånd. I flera fall framkom indirekt, men ändå tydligt, att utbildningen på tekniken hade varit otillräcklig, trots att lärarna inte uttryckte ett tydligt missnöje med den. Skrivtavlan ökade lärarnas motivation för samarbete. En framåtriktad slutsats är att en lärargrupp som har ett fungerande samarbete och goda didaktiska, ämnesmässiga, ledar- och relationella kompe¬tenser med en interaktiv skrivtavla har en möjlighet att komma längre med elevernas måluppfyllelse.

Series
Blekinge Tekniska Högskola Forskningsrapport, ISSN 1103-1581 ; 2
Keywords
IKT, matematik, skolan, aktivitetsteori, datorer, interaktiv skrivtavla, måluppfyllelse
National Category
Mathematics Pedagogy
Identifiers
urn:nbn:se:bth-00521 (URN)oai:bth.se:forskinfo8192362F920B2EF0C12579B1003DBED6 (Local ID)oai:bth.se:forskinfo8192362F920B2EF0C12579B1003DBED6 (Archive number)oai:bth.se:forskinfo8192362F920B2EF0C12579B1003DBED6 (OAI)
External cooperation:
Available from: 2012-09-18 Created: 2012-02-27 Last updated: 2016-09-06Bibliographically approved
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