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  • 251.
    Ahlström, Daniel
    Linköping University, Department of Computer and Information Science. Linköping University, The Institute of Technology.
    Minimizing memory requirements for deterministic test data in embedded testing2010Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Embedded and automated tests reduce maintenance costs for embedded systems installed in remote locations. Testing multiple components of an embedded system, connected on a scan chain, using deterministic test patterns stored in a system provide high fault coverage but require large system memory. This thesis presents an approach to reduce test data memory requirements by the use of a test controller program, utilizing the observation of that there are multiple components of the same type in a system. The program use deterministic test patterns specific to every component type, which is stored in system memory, to create fully defined test patterns when needed. By storing deterministic test patterns specific to every component type, the program can use the test patterns for multiple tests and several times within the same test. The program also has the ability to test parts of a system without affecting the normal functional operation of the rest of the components in the system and without an increase of test data memory requirements. Two experiments were conducted to determine how much test data memory requirements are reduced using the approach presented in this thesis. The results for the experiments show up to 26.4% reduction of test data memory requirements for ITC´02 SOC test benchmarks and in average 60% reduction of test data memory requirements for designs generated to gain statistical data.

  • 252.
    Ahlström, Mattias
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Development of an Attractive Network for Regional Bus Traffic in Dalarna County2015Independent thesis Basic level (degree of Bachelor), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Även om direktbusstrafiken i Dalarnas län redan i dagsläget trafikerar relativt raka och snabba linjesträckningar anser länstrafikbolaget Dalatrafik att det finns potential till att ytterligare sänka restiderna för att locka fler resenärer. Fyra av länets viktigaste direktbusslinjer har därför studerats och för var och en av dessa har ett antal förändringsåtgärder tagits fram. Målet med förändringsåtgärderna har varit att, i första hand, åstadkomma en rakare linjesträckning och utreda hur mycket restiden skulle komma att förändras om bussen istället kör den nya vägen. Utifrån befintlig resandestatistik över hur många resenärer som reser på varje sträcka har den totala tidsbesparingen för samtliga förändringsåtgärder per linje beräknats och detta har givits ett monetärt värde. Genom täckningsanalyser har befolkningen inom upptagningsområdet kring varje hållplats beräknats, detta för att visa hur tillgängligheten till respektive linje förändras efter ett eventuellt införande av de föreslagna åtgärderna.

  • 253.
    Ahlström, Per
    Linköping University, Department of Electrical Engineering. Linköping University, The Institute of Technology.
    Signalprediktering i vitt gaussiskt brus med hjälp av ett adaptivt signalanpassat filter1976Report (Other academic)
    Abstract [sv]

    Ett signalanpassat filter har ett impulssvar som är den exiterandesignalens spegelbild . Ett dylikt filter maximerar vid en viss tidpunkt signalbrusförhållandet på utgången.

    Ett adaptivt transversalfilter styrt av en gradientkännande algoritm, vilken maximerar signalbrusförhållandet på filterutgången, har studerats. Det spegelvända impulssvaret har använts som prediktion av signalen. Denna prediktion har, vid simulering gjord på dator, ej visat sig vara bättre än en klassisk prediktion med en ren summering av brusstörda upplagor av signalen. Inte ens då dylika summerade upplagor av den brusstörda signalenanvänts som insignal till filtret har signalprediktionen via filtrets impulssvar uppvisat ett lägre kvadratiskt medelfel än d en klassiska.

  • 254.
    Ahlström, Petter
    Linköping University, Department of Computer and Information Science, EISLAB - Economic Information Systems. Linköping University, The Institute of Technology.
    Affärsstrategier för seniorbostadsmarknaden2005Licentiate thesis, monograph (Other academic)
    Abstract [sv]

    Den demografiska utvecklingen i Sverige går mot en befolkningssammansättning med allt högre medelålder. Enligt svenska befolkningsprognoser kommer nästan var fjärde svensk år 2025 att vara över 65 år. Den äldre andelen av befolkningen utgör en välbeställd grupp med relativt stora realekonomiska tillgångar. Attitydundersökningar på morgondagens pensionärer talar för att denna grupp ställer högre krav på boendeutformning, kringservice, vård och omsorg än tidigare generationer. Flera studier visar på en ökad betalningsvilja och betalningsförmåga för alternativa service- och boendeformer. Samtidigt försöker olika marknadsaktörer att positionera ett produkt- och tjänsteutbud inom en bostadsmarknadens nischer, här definierad som seniorbostadsmarknaden. På seniorbostadsmarknaden har ett särskilt segment identifierats där utöver seniorboende även service-, vård- och omsorgsrelaterade kringtjänster bjuds ut. Mot den bakgrunden har avhandlingens problemställning formulerats enligt följande: vad skapar en stark marknadsposition för en aktör på seniorbostadsmarknaden med integrerad service, vård och omsorg?

    Utgångspunkten har varit ett sannolikt scenario där privata initiativ i allt större utsträckning kommer att bidra till framtida boendelösningar riktade till samhällets seniora och äldrebefolkningsgrupper. Syftet med avhandlingen har varit dels att identifiera de framgångsfaktorer som kan antas ligger till grund för en stark marknadsposition, dels att skapa en typologi över olika affärsstrategier. Genom en branschanalys har det i avhandlingen påvisats att seniorbostadsmarknaden är en nischmarknad med marginell omfattning. Avhandlingens empiriska undersökning har designats som en fältstudie. Fältstudien har i sin tur bl.a. genomförts i form av en förstudie och en intervjustudie. Intervjustudien ägde rum under hösten 2004 med platsbesök och intervjuer av verksamhetsföreträdare för elva utvalda fallstudieorganisationer. Utifrån ett antal i förhand uppställda kriterier har marknadsaktörernas framgångsfaktorer identifierats. Den bearbetnings- och analysmodell som konstruerats för detta syfte och som använts för att analysera fältstudiens empiri är baserad på studier inom strategiområdet. Modellen har bl.a. inspirerats av forskare som Miles & Snow (1978), Porter (1980) och Gupta & Govindarajan (1984). Vidare bygger den på antagandena om resursers och kompetensers betydelse för strategiformuleringen. Service management, och då särskilt tjänsters sammansättning, är ett annat område som beaktas. Analysmodellen har byggts upp kring fem dimensioner: omgivning, strategi, resurser, tjänstekoncept och konkurrens. De identifierade framgångsfaktorerna har baserats på intervjustudiens två mest framgångsrika aktörer. Resultatet har formulerats i ett antal strategiska vägval vilka kan sammanfattas i begreppen: differentiering, fokus, integration, samverkan, kontroll, verksamhetsutveckling, kärnkompetens och resurser. I avhandlingen påvisas att aktörer som bedriver framgångsrik verksamhet på seniorbostadsmarknaden till stora delar följer det Porter (1980) definierat som en differentieringsstrategi med fokus. Avhandlingen har också utmynnat i en affärsstrategisk typologi för seniorbostadsmarknaden. Dessa tentativa slutsatser har formulerats i fyra strategiska idealtyper: förvaltare, konceptbyggare, entreprenörer och idealister.

  • 255.
    Ahlström, Petter
    Linköping University, Department of Management and Engineering, Economic Information Systems. Linköping University, The Institute of Technology.
    Strategier och styrsystem för seniorboendemarknaden2008Doctoral thesis, monograph (Other academic)
    Abstract [en]

    The demographic trend in Sweden features a population with a rising average age. According to forecasts, nearly one Swede out of four will be 65 or older by the year 2025. Many individuals in this category of older persons, or seniors, can look forward to an active, healthy and relatively long old age. Studies have shown that tomorrow’s seniors and retirees will be relatively well off as social groups. In addition, attitude and generation surveys have indicated that these groups have high demands and expectations for their old age, future housing and related services. Society will thus face a considerable challenge, which includes maintaining a basic commitment to continue guaranteeing the standard of quality in housing and services for the elderly that is presently taken for granted. Necessary societal priorities, however, may require individuals to take more initiative and assume greater financial responsibility than before in some of these areas. In the 2000’s a new market segment has been established and shown vigorous growth. That segment is the senior housing market, where various housing concepts are offered to the target group, seniors, or persons aged 55+. The number of senior housing units in Sweden has soared in the last few years, from about 10 000 in 2000 to some 28 000 in 2007. In this study, the concept of senior housing, with features of integrated service and care, has been of special interest. What characterizes this housing concept is that housing and related services have been adapted and specially designed for living as an aging individual.

    This dissertation (”the survey”) is reported in the form of a monograph consisting of two separate studies. The research question that has guided the first study is, “What creates a strong market position for a player on the senior-housing market with integrated service, health care and other forms of service and care?” The research question for the second study is, “What production strategies and control systems can be identified for some of the most successful concept-builders?” The two studies are related in that the latter is based on the results of the former. The studies were conducted over a period from 2002 to 2008. The research was done as an exploratory field study. The field-study approach has given priority to breadth and inclusion of many aspects. The instrument of measurement has consisted of set interview questions with open-ended alternative responses. The underlying interviews, together with secondary data, have been presented as a number of case studies. In the survey, a number of successful players have been selected on the basis of the criteria considered typical of successful actors on the senior housing market. Both Swedish and North American organizations have participated in the survey.

    The empirical material of the survey has been analyzed on the basis of the theoretical conceptual frameworks developed for the two respective studies. The first study has been analyzed with a framework based on the concepts of environment, strategy, resources, service and competitiveness. The results have been formulated in a number of strategic choices that are summarized in the concepts of differentiation, focus, integration, collaboration, control, business development, core competence and resources. In this connection, it has been possible to show that actors who operate a successful business follow largely what Porter (1980) has defined as a strategy of differentiation. Moreover, a business-strategy typology of actors on the senior housing market has also been constructed. Also, the tentative conclusions of the first study have been formulated in four strategic ideal types: administrators, concept-builders, entrepreneurs and idealists.

    The point of departure for the second study has been the ideal type referred to as the concept-builder. The conceptual framework has therefore been developed further, based in part on the theoretical framework of Nilsson and Rapp (2005). With certain additions, these foundations have been used to construct a detailed theoretical framework for the study. The conceptual framework has been designed to describe and analyze the causal relationships relating to strategic congruence and integrated control. In this regard, additions and adjustments have been made to include strategies and control systems for the construction of buildings and the production of services. The results of the second study include a case description and an analysis of successful concept-builders. One reason for their success is assumed to be their ability to achieve strategic congruence and integrated control. In light of the findings from the analysis of the data, the conceptual framework has been somewhat modified. This adjustment has consisted in classification along the dimensions of IT, organizational culture and fundamental values. In this connection it has been possible to demonstrate the importance of the physical planning of housing for the production of services. Emphasis has been placed on designing the physical facility and housing right from the beginning so as to facilitate the service-producing operation in a later stage of the life cycle.

    One finding of the survey is that with North American concept-builders there is a high degree of consistency between strategies and control systems. The factors underlying this consistency can be summarized as market knowledge, industry experience, understanding the economies of scale attainable through clustering, organization on a small scale, a clear concept of business, a sense of value creation, a focus on objectives, farreaching delegation of authority and responsibility to the operating level, skilled management, value-oriented operations and a well-developed organizational culture. Through the survey, a number of customer-controlled operations have been illustrated in the case studies. It is apparent that compared to the past, there has been a shift in industry attitude in North America, creating a situation that differs from Swedish conditions in some respects. The North American concept-builders have defined their businesses as hotel operations for seniors. This has automatically shifted the focus toward one where residents have become customers and older people in general are regarded as assets.

  • 256.
    Ahlström, Petter
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, EISLAB - Economic Information Systems.
    Nilsson, Fredrik
    Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, EISLAB - Economic Information Systems.
    Affärsstrategier och seniorbostadsmarknaden2005In: Fastighetsnytt, ISSN 1104-8913, Vol. 12 nr 5, 36-37 p.Article in journal (Other (popular science, discussion, etc.))
    Abstract [sv]

      Artikeln beskriver några av resultaten från licentiatavhandlingen "Affärsstrategier för seniorbostadsmarknaden" av Petter Ahlström.      

  • 257.
    Ahlström, Petter
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Management and Engineering.
    Nilsson, Fredrik
    Linköping University, The Institute of Technology. Linköping University, Department of Management and Engineering.
    Boende för äldre - utmaningar och möjligheter2007Report (Other academic)
    Abstract [sv]

    Det projekt som här avrapporteras är initierat och finansierat av Sveriges Kommuner och Landstings FoU-fond för fastighetsfrågor. I rapporten diskuteras och analyseras ett antal faktorer som kan antas påverka kommunernas kostnader, i vid bemärkelse, för service, vård och omsorg. Analysen inriktas på hur utformningen av dagens och framtidens boende för äldre kan antas påverka kostnadsläget. Rapporten omfattar 88 sidor.        

  • 258.
    Ahlström, Petter
    et al.
    Linköping University, Department of Computer and Information Science, EISLAB - Economic Information Systems. Linköping University, The Institute of Technology.
    Nilsson, Fredrik
    Linköping University, Department of Computer and Information Science, EISLAB - Economic Information Systems. Linköping University, The Institute of Technology.
    Interaktivt forskningssamarbete med seniorbostadsentreprenörer2003In: The 17th Nordic Conference on Business Studies in Reykjavik, 2003Conference paper (Refereed)
  • 259.
    Ahlström, Petter
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, EISLAB - Economic Information Systems.
    Nilsson, Fredrik
    Linköping University, The Institute of Technology. Linköping University, Department of Management and Engineering.
    Olve, Nils-Göran
    Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, EISLAB - Economic Information Systems.
    Att mobilisera och vårda samverkan i forskning2007In: Högskolor och samhälle i samverkan 2007 HSS07,2007, 2007Conference paper (Other academic)
    Abstract [en]

    Kunskapsutveckling är en långsiktig process där kontaktskapande och kontaktvård ofta har stor omfattning jämfört med den konkreta forskningsinsatsen. Utmaningen är att mobilisera och vårda en allians där forskare och praktiker samverkar. Ibland kan även finansiärer ha en aktiv roll. Intresse för forskningsinsatsen är en viktig utgångspunkt för samverkan men inte sällan finns det ytterligare orsaker till att ett samarbete kommer till stånd och består. Teoretisk inspiration för att diskutera detta kan hämtas från studier av s.k. imaginära och virtuella organisationer. I uppsatsen diskuteras detta mot bakgrund av erfarenheter från faktiska forskningsprojekt.     

  • 260.
    Ahlström, Petter
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Management and Engineering, Economic Information Systems.
    Nilsson, Fredrik
    Linköping University, The Institute of Technology. Linköping University, Department of Management and Engineering, Economic Information Systems.
    Olve, Nils-Göran
    Linköping University, The Institute of Technology. Linköping University, Department of Management and Engineering, Economic Information Systems.
    Att mobilisera och vårda samverkan i forskning2008In: Gemensamt kunskapande - den interaktiva forskningens praktik, Växjö: Växjö University Press , 2008, 1, 115-132 p.Chapter in book (Other academic)
    Abstract [sv]

    I en tid då universitetens kunskapsmonopol är på väg att brytas får en nära samverkan mellan forskare, finansiär och studieobjekt en allt större betydelse (Nowotny et al., 2002, "Re-thinking Science"). Denna typ av samverkan är en central utgångspunkt i interaktiv forskning där ett vanligt syfte är att bedriva praktiknära studier med stor utomvetenskaplig relevans. I denna uppsats diskuteras hur samverkan mobiliseras och vårdas. Frågor som behandlas är hur forskarnas och praktikernas intressen ska förenas samt vad forskarna kan göra för att skapa rimliga förväntningar hos praktikerna och sprida sina resultat. Diskussionen baseras på egna erfarenheter där ett antal minifall får illustrera vad vi uppfattar vara typiska utmaningar i den här typen av samarbeten.   

  • 261.
    Ahlström, Petter
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Management and Engineering, Economic Information Systems.
    Nilsson, Fredrik
    Linköping University, The Institute of Technology. Linköping University, Department of Management and Engineering, Economic Information Systems.
    Olve, Nils-Göran
    Linköping University, The Institute of Technology. Linköping University, Department of Management and Engineering, Economic Information Systems.
    Mobilising and nurturing collaboration in research - the value of a focused imagination2007In: International Journal of Action Research, ISSN 1861-1303, E-ISSN 1861-9916, Vol. 3, no No 3, 297-327 p.Article in journal (Refereed)
    Abstract [en]

       Establishing and nurturing contacts are important and time-consuming elements of interactive research. It is usually the researcher who has to establish and nurture collaboration with practitioners, a task that is not normally part of traditional research. A mutual interest in the subject of the research is a prerequisite for collaboration, but there are quite often other factors that explain why collaboration begins and endures. On the basis of the experience gained in a number of interactive research projects, we address the conditions required for an effective and lasting interplay between collaborating partners. Theoretical inspiration has been provided by studies of so-called imaginary organisations.        

  • 262.
    Ahmad, Ban
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Vieglins, Gustav
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    A energy and cost comparison between a BBR and a passive apartment building2016Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Idag ställer samhället och konsumenterna allt större krav på klimatsmarta boenden för att minska energianvändningen. Trots det byggs fortfarande till stor del traditionella hus efter Boverkets byggregler. På uppdrag av WSP studerar denna rapport hur energiåtgången hos ett befintligt flerbostadshus i Stockholm, byggt efter BBR, hade sett ut om det uppförts för att fylla kravspecifikationen för passivhus enligt FEBY12. Samt hur livscykelkostnaderna hade skiljt sig för de två husen.

    Studien inleddes med en datainsamling av för det befintliga flerbostadshusets areor samt Uvärdena och följs upp med simuleringar av flerbostadshuset i beräkningsprogrammet Energihuskalkyl. Datorberäkningarna jämfördes med manuella beräkningar för att säkerställa värmeförlusttalet samt andelen köpt energi. Varefter flerbostadshuset anpassades med Kingspans detaljbibliotek för att uppfylla FEBY12s passivhuskrav och följdes upp med samma dator- och manuella beräkningar. Där de båda resultaten presenteras och jämförs.

    I rapportens andra del undersöks och jämförs de två flerbostadshusens livscykelkostnader, sett till investerings-, drifts- och underhållskostnader. Då beställaren sekretessbelagt de verkliga kostnaderna antogs de verkliga kostnaderna för det befintliga huset från Statistiska Centralbyrån. För att beräkna det teoretiska passivhusets investeringskostnader beräknades materialkostnaderna för de båda husen efter de givna ritningarna. Där skillnaden i materialkostnaderna adderades till investeringskostnaden för det passiva flerbostadshuset.

    Underhållskostnaderna antogs till detsamma för det passiva flerbostadshuset samtidigt som att driftskostnaderna sänktes procentuellt med den minskade mängden köpt energi från energiberäkningarna.

  • 263.
    Ahmad, M. Rauf
    Linköping University, Department of Mathematics, Mathematical Statistics . Linköping University, The Institute of Technology.
    A two-sample test statistic for high-dimensional multivariate data under non-normality2011Report (Other academic)
    Abstract [en]

    Ahmad, Ohlson, and von Rosen (2011a) present asymptotic distribution of a one-sample test statistic under non-normality, when the data are high dimensional, i.e., when the dimension of the vector, p, may exceed the sample size, n. This paper extends the case to a two-sample statistic to test the difference of mean vectors of two independent multivariate distributions, again under high-dimensional set up. Using the asymptotic theory of U-statistics, and under mild assumptions on the traces of the unknown covariance matrices, the statistic is shown to follow an approximate normal distribution when n and p are large. However, no relationship between n and p is assumed. An extension to the paired case is given, which, being essentially a one-sample statistic, supplements the asymptotic results obtained in Ahmad, Ohlson, and von Rosen (2011a).

  • 264.
    Ahmad, M. Rauf
    Linköping University, Department of Mathematics. Linköping University, The Institute of Technology.
    Robustness of a one-sample statistic for mean testing of high dimensional longitudinal data2010Report (Other academic)
  • 265.
    Ahmad, M. Rauf
    et al.
    Linköping University, Department of Mathematics, Mathematical Statistics . Linköping University, The Institute of Technology.
    Ohlson, Martin
    Linköping University, Department of Mathematics, Mathematical Statistics . Linköping University, The Institute of Technology.
    von Rosen, Dietrich
    Linköping University, Department of Mathematics, Mathematical Statistics . Linköping University, The Institute of Technology.
    A U-statistics Based Approach to Mean Testing for High Dimensional Multivariate Data Under Non-normality2011Report (Other academic)
    Abstract [en]

    A test statistic is considered for testing a hypothesis for the mean vector for multivariate data, when the dimension of the vector, p, may exceed the number of vectors, n, and the underlying distribution need not necessarily be normal. With n, p large, and under mild assumptions, the statistic is shown to asymptotically follow a normal distribution. A by product of the paper is the approximate distribution of a quadratic form, based on the reformulation of well-known Box's approximation, under high-dimensional set up.

  • 266.
    Ahmad, M. Rauf
    et al.
    Linköping University, Department of Mathematics, Mathematical Statistics . Linköping University, The Institute of Technology.
    Ohlson, Martin
    Linköping University, Department of Mathematics, Mathematical Statistics . Linköping University, The Institute of Technology.
    von Rosen, Dietrich
    Department of Energy and Technology, Swedish Univerity of Agricultural Sciences, SE-750 07 Uppsala, Sweden.
    Some Tests of Covariance Matrices for High Dimensional Multivariate Data2011Report (Other academic)
    Abstract [en]

    Test statistics for sphericity and identity of the covariance matrix are presented, when the data are multivariate normal and the dimension, p, can exceed the sample size, n. Using the asymptotic theory of U-statistics, the test statistics are shown to follow an approximate normal distribution for large p, also when p >> n. The statistics are derived under very general conditions, particularly avoiding any strict assumptions on the traces of the unknown covariance matrix. Neither any relationship between n and p is assumed. The accuracy of the statistics is shown through simulation results, particularly emphasizing the case when p can be much larger than n. The validity of the commonly used assumptions for high-dimensional set up is also briefly discussed.

  • 267.
    Ahmad, M. Rauf
    et al.
    Uppsala University, Sweden; Swedish University of Agriculture Science, Sweden.
    von Rosen, Dietrich
    Linköping University, Department of Mathematics, Mathematical Statistics . Linköping University, The Institute of Technology. Swedish University of Agriculture Science, Sweden.
    Tests of Covariance Matrices for High Dimensional Multivariate Data Under Non Normality2015In: Communications in Statistics - Theory and Methods, ISSN 0361-0926, E-ISSN 1532-415X, Vol. 44, no 7, 1387-1398 p.Article in journal (Refereed)
    Abstract [en]

    Ahmad et al. (in press) presented test statistics for sphericity and identity of the covariance matrix of a multivariate normal distribution when the dimension, p, exceeds the sample size, n. In this note, we show that their statistics are robust to normality assumption, when normality is replaced with certain mild assumptions on the traces of the covariance matrix. Under such assumptions, the test statistics are shown to follow the same asymptotic normal distribution as under normality for large p, also whenp greater thangreater than n. The asymptotic normality is proved using the theory of U-statistics, and is based on very general conditions, particularly avoiding any relationship between n and p.

  • 268.
    Ahmad, M. Rauf
    et al.
    Swedish University of Agricultural Sciences, Uppsala, Sweden and Department of Statistics, Uppsala University, Sweden.
    von Rosen, Dietrich
    Linköping University, Department of Mathematics, Mathematical Statistics . Linköping University, The Institute of Technology.
    Singull, Martin
    Linköping University, Department of Mathematics, Mathematical Statistics . Linköping University, The Institute of Technology.
    A note on mean testing for high dimensional multivariate data under non-normality2013In: Statistica neerlandica (Print), ISSN 0039-0402, E-ISSN 1467-9574, Vol. 67, no 1, 81-99 p.Article in journal (Refereed)
    Abstract [en]

    A test statistic is considered for testing a hypothesis for the mean vector for multivariate data, when the dimension of the vector, p, may exceed the number of vectors, n, and the underlying distribution need not necessarily be normal. With n,p→∞, and under mild assumptions, but without assuming any relationship between n and p, the statistic is shown to asymptotically follow a chi-square distribution. A by product of the paper is the approximate distribution of a quadratic form, based on the reformulation of the well-known Box's approximation, under high-dimensional set up. Using a classical limit theorem, the approximation is further extended to an asymptotic normal limit under the same high dimensional set up. The simulation results, generated under different parameter settings, are used to show the accuracy of the approximation for moderate n and large p.

  • 269.
    Ahmad, Shakeel
    Linköping University, Department of Electrical Engineering, Electronic Devices. Linköping University, The Institute of Technology.
    Stimuli Generation Techniques for On-Chip Mixed-Signal Test2010Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    With increased complexity of the contemporary very large integrated circuits the need for onchip test addressing not only the digital but also analog and mixed-signal RF blocks has emerged. The standard production test has become more costly and the instrumentation is pushed to its limits by the leading edge integrated circuit technologies. Also the chip performance for high frequency operation and the area overhead appear a hindrance in terms of the test access points needed for the instrumentation-based test. To overcome these problems, test implemented on a chip can be used by sharing the available resources such as digital signal processing (DSP) and A/D, D/A converters to constitute a built-in-self-test. In this case, the DSP can serve both as a stimuli generator and response analyzer.

    Arbitrary test signals can be achieved using DSP. Specifically, the ΣΔ modulation technique implemented in software is useful to encode a single- or two-tone stimulus as a onebit sequence to generate a spectrally pure signal with a high dynamic range. The sequence can be stored in a cyclic memory on a chip and applied to the circuit under test using a buffer and a simple reconstruction filter. In this way ADC dynamic test for harmonic and intermodulation distortion is carried out in a simple setup. The FFT artifacts are avoided by careful frequency planning for low-pass and band-pass ΣΔ encoding technique. A noise shaping based on a combination of low- and band-pass ΣΔ modulation is also useful providing a high dynamic range for measurements at high frequencies that is a new approach. However, a possible asymmetry between rise and fall time due to CMOS process variations in the driving buffer results in nonlinear distortion and increased noise at low frequencies. A simple iterative predistortion technique is used to reduce the low frequency distortion components by making use of an on-chip DC calibrated ADC that is another contribution of the author.

    Some tests, however, like the two-tone RF test that targets linearity performance of a radio receiver, require test stimuli based on a dedicated hardware. For the measurement of the thirdor second-intercept point (IP3/IP2) a spectrally clean stimulus is essential. Specifically, the second- or third-order harmonic or intermodulation products of the stimulus generator should be avoided as they can obscure the test measurement. A challenge in this design is the phase noise performance and spurious tones of the oscillators, and also the distortion-free addition of the two tones. The mutual pulling effect can be minimized by layout isolation techniques.

    A new two-tone RF generator based on a specialized phase-locked loop (PLL) architecture is presented as a viable solution for IP3/IP2 on-chip test. The PLL provides control over the frequency spacing of two voltage controlled oscillators. For the two-tone stimulus a highly linear analog  adder is designed to limit distortion which could obscure the IP3 test. A specialized feedback circuit in the PLL is proposed to overcome interference by the reference spurs. The circuit is designed using 65 nm CMOS process. By using a fine spectral resolution the observed noise floor can be reduced to enable the measurement of second- or third-order intermodulation product tones. This also reflects a tradeoff between the test time and the test performance. While the test time to collect the required number of samples can be of milliseconds the number of samples need not be excessive, since the measurements are carried out at the receiver baseband, where the required sampling frequency is relatively low.

  • 270.
    Ahmad, Shakeel
    et al.
    Linköping University, Department of Electrical Engineering, Electronic Devices. Linköping University, The Institute of Technology.
    Azizi, Kaveh
    Linköping University, Department of Electrical Engineering, Electronic Devices. Linköping University, The Institute of Technology.
    Esmaeil Zadeh, Iman
    Linköping University, Department of Electrical Engineering, Electronic Devices. Linköping University, The Institute of Technology.
    Dabrowski, Jerzy
    Linköping University, Department of Electrical Engineering, Electronic Devices. Linköping University, The Institute of Technology.
    Two-tone PLL for on-chip IP3 test2010In: Proceedings of IEEEInternational Symposium on Circuits and Systems, (ISCAS 10), IEEE , 2010, 3549-3552 p.Conference paper (Refereed)
    Abstract [en]

    This paper addresses a built-in-self-test (BiST) to characterize IP3 linearity of a RF receiver front-end. A two-tone stimulus is generated by a phase-lock loop (PLL) in GHz frequency range. The PLL is designed to keep the frequency difference between the two tones under control and in this way to avoid a possible injection-locking. One of the oscillation frequencies and the difference (beat) frequency can be externally controlled. According to the test requirements the phase noise and nonlinear distortion of the two-tone generator are considered as a merit for the VCO and analog adder design. A highly linear analog adder with output referred IP3 of more than +15 dBm is used to generate the RF stimulus. The two-tone power across 50 Ω receiver input impedance can be more than -25 dBm with very low intermodulation distortion of PIM3 = -75 dBc. The receiver performance is not affected significantly by the test set-up. Simulations for linearity and noise performance of the PLL designed in 65nm CMOS show sufficient potential for on-chip IP3 measurements in the GHz frequency range.

  • 271.
    Ahmad, Shakeel
    et al.
    Linköping University, Department of Electrical Engineering, Electronic Devices. Linköping University, The Institute of Technology.
    Azizi, Kaveh
    Linköping University, Department of Electrical Engineering, Electronic Devices. Linköping University, The Institute of Technology.
    Esmaeil Zadeh, Iman
    Linköping University, Department of Electrical Engineering, Electronic Devices. Linköping University, The Institute of Technology.
    Dabrowski, Jerzy
    Linköping University, Department of Electrical Engineering, Electronic Devices. Linköping University, The Institute of Technology.
    Two-Tone PLL for on-Chip IP3 Test2010In: Swedish System-on-Chip Conference, 2010Conference paper (Other academic)
  • 272.
    Ahmad, Shakeel
    et al.
    Linköping University, Department of Electrical Engineering, Electronic Devices. Linköping University, The Institute of Technology.
    Dabrowski, Jerzy
    Linköping University, Department of Electrical Engineering, Electronic Devices. Linköping University, The Institute of Technology.
    ADC on-Chip Dynamic Test by PWM Technique2008In: International Conference on Signals and Electronic Systems, IEEE , 2008, 15-18 p.Conference paper (Refereed)
    Abstract [en]

    This paper investigates the feasibility of pulse width modulation technique (PWM) for dynamic test of ADCs used for high speed applications. The requirements and limitations of digital PWM signal to noise ratio (SNR) are discussed in terms of pulse-width resolution corresponding to the choice of the carrier- and clock frequency of a pulse-width generator. The PWM SNR response is measured by FFT using coherent sampling for different PWM resolution. Low-pas filtering removing high frequency PWM components is introduced as well to improve PWM SNR and prevent intermodulation effects, which tend to hamper the harmonic distortion test (HD). As an example a 4-bit first-order SigmaDelta ADC under dynamic test is simulated and the requirements for PWM resolution with respect to SNR and HD measurements are identified.

  • 273.
    Ahmad, Shakeel
    et al.
    Linköping University, Department of Electrical Engineering, Electronic Devices. Linköping University, The Institute of Technology.
    Dabrowski, Jerzy
    Linköping University, Department of Electrical Engineering, Electronic Devices. Linköping University, The Institute of Technology.
    Cancellation of Spurious Spectral Components in One-Bit Stimuli Generator2010In: Proceedings of IEEEInternational Conference on Signals and Electronic Systems, (ICSES 10) / [ed] Andrzej Pułka and Tomasz Golonek, IEEE , 2010, 393-396 p.Conference paper (Refereed)
    Abstract [en]

    This work presents a cancellation technique of non-linear distortion components of one-bit digital stimulus sequence which is generated in software by a ΣΔ modulator. The stimulus is stored in a cyclic memory and applied to a circuit under test through a driving buffer and a simple lowpass reconstruction filter. The distortion components originate from buffer imperfections which result in a possible asymmetry between rising and falling edges of a NRTZ waveform representing the encoded stimulus. We show that the distortion components can be cancelled by using a simple predistortion technique. In addition an on-chip DC-calibrated ADC can be used to identify the second-order nonlinear products of the driving buffer. This procedure allows for cancellation of all the second-order distortions before the actual test and it can be extended to the third order terms as well.

  • 274.
    Ahmad, Shakeel
    et al.
    Linköping University, Department of Electrical Engineering, Electronic Devices. Linköping University, The Institute of Technology.
    Dabrowski, Jerzy
    Linköping University, Department of Electrical Engineering, Electronic Devices. Linköping University, The Institute of Technology.
    Design of Two-Tone RFGenerator for On-Chip IP3/IP2 TestManuscript (preprint) (Other academic)
  • 275.
    Ahmad, Shakeel
    et al.
    Linköping University, Department of Electrical Engineering, Electronic Devices. Linköping University, The Institute of Technology.
    Dabrowski, Jerzy
    Linköping University, Department of Electrical Engineering, Electronic Devices. Linköping University, The Institute of Technology.
    On-Chip Spectral Test for High-Speed ADCs by ΣΔ Technique2011In: European Conference on Circuit Theory and Design (ECCTD), Linköping, Sweden: IEEE conference proceedings, 2011, 661-664 p.Conference paper (Refereed)
    Abstract [en]

    Application of the ΣΔ modulation technique to the on-chip spectral test for high-speed A/D converters is presented. The harmonic HD2/HD3 and intermodulation IM2/IM3 test is obtained with one-bit ΣΔ sequence stored in a cyclic memory or generated on line, and applied to an ADC under test through a driving buffer and a simple reconstruction filter. To achieve a dynamic range (DR) suitable for high-performance spectral measurements a frequency plan is used taking into account the type of ΣΔ modulation (low-pass and band-pass) including the FFT processing gain. Higher order modulation schemes are avoided to manage the ΣΔ quantization noise without resorting to a more complicated filter. For spectral measurements up to the Nyquist frequency, we propose a dedicated low-pass/band-pass ΣΔ modulation scheme that limits spreading of the low-frequency quantization noise by ADC under test that tends to obstruct the test measurements at high frequencies. Correction technique for NRTZ encoding suitable for ADCs with very high clock frequencies is put in perspective. The presented technique is illustrated by simulation examples of a Nyquist-rate ADC under test.

  • 276.
    Ahmad, Shakeel
    et al.
    Linköping University, Department of Electrical Engineering, Electronic Devices. Linköping University, The Institute of Technology.
    Dabrowski, Jerzy
    Linköping University, Department of Electrical Engineering, Electronic Devices. Linköping University, The Institute of Technology.
    On-chip Stimuli Generation for ADC Dynamic Test by ΣΔ Technique2009In: Proceedings in European Conference on Circuit Theory and Design 2009 (ECCTD´09), Antalya, Turkey, IEEE , 2009, 105-108 p.Conference paper (Refereed)
    Abstract [en]

    This paper presents application of the ΣΔ modulation technique to the on-chip dynamic test for A/D converters. The wanted stimulus such as a single- or two-tone signal is encoded into one-bit ΣΔ sequence, which after simple low-pass filtering is applied to the circuit under test with low noise and without distortion. In this way a large dynamic range is achieved making the performance harmonic- and intermodulation dynamic test viable. By a systematic approach we select the order and type of a ΣΔ modulator, and develop the frequency plan suitable for spectral measurements on a chip. The technique is illustrated by simulation of a practical ADC under test.

  • 277.
    Ahmad, Shakeel
    et al.
    Linköping University, Department of Electrical Engineering, Electronic Devices. Linköping University, The Institute of Technology.
    Dabrowski, Jerzy
    Linköping University, Department of Electrical Engineering, Electronic Devices. Linköping University, The Institute of Technology.
    One-bit ΣΔ Encoded StimulusGeneration for on-Chip ADC Test2010In: Journal of electronic testing, ISSN 0923-8174, E-ISSN 1573-0727Article in journal (Other academic)
  • 278. Ahmad, Tausif
    et al.
    Gooran, Sasan
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Hybrid Color Halftoning2010Conference paper (Refereed)
  • 279.
    Ahmed Aamir, Syed
    et al.
    University of Bielefeld, Germany .
    Angelov, Pavel
    AnaCatum Design AB, Linkoping, Sweden .
    Wikner, Jacob
    Linköping University, Department of Electrical Engineering, Electronics System. Linköping University, The Institute of Technology.
    1.2-V Analog Interface for a 300-MSps HD Video Digitizer in Core 65-nm CMOS2014In: IEEE Transactions on Very Large Scale Integration (vlsi) Systems, ISSN 1063-8210, E-ISSN 1557-9999, Vol. 22, no 4, 888-898 p.Article in journal (Refereed)
    Abstract [en]

    This paper describes the front-end of a fully integrated analog interface for 300 MSps, high-definition video digitizers in a system on-chip environment. The analog interface is implemented in a 1.2 V, 65-nm digital CMOS process and the design minimizes the number of power domains using core transistors only. Each analog video receiver channel contains an integrated multiplexer with a current-mode dc-clamp, a programmable gain amplifier (PGA) and a pseudo second-order RC low-pass filter. The digital charge-pump clamp is integrated with low-voltage bootstrapped tee-switches inside the multiplexer, while restoring the dc component of ac-coupled inputs. The PGA contains a four-stage fully symmetric pseudo-differential amplifier with common-mode feedforward and inherent common-mode feedback, utilized in a closed loop capacitive feedback configuration. The amplifier features offset cancellation during the horizontal blanking. The video interface is evaluated using a unique test signal over a range of video formats for INL+/DNL+, INL-/DNL-. The 0.07-0.39 mV INL, 2-70 mu V DNL, and 66-74 dB of SFDR, enable us to target various formats for 9-12 bit Low-voltage digitizers.

  • 280.
    Ahmed Aamir, Syed
    et al.
    Linköping University, Department of Electrical Engineering. Linköping University, The Institute of Technology.
    Harikumar, Prakash
    Linköping University, Department of Electrical Engineering, Electronics System. Linköping University, The Institute of Technology.
    Wikner, Jacob J
    Linköping University, Department of Electrical Engineering, Electronics System. Linköping University, The Institute of Technology.
    Frequency compensation of high-speed, low-voltage CMOS multistage amplifiers2013In: IEEE International Symposium on Circuits and Systems (ISCAS), 2013, IEEE conference proceedings, 2013, 381-384 p.Conference paper (Refereed)
    Abstract [en]

    This paper presents the frequency compensation of high-speed, low-voltage multistage amplifiers. Two frequency compensation techniques, the Nested Miller Compensation with Nulling Resistors (NMCNR) and Reversed Nested Indirect Compensation (RNIC), are discussed and employed on two multistage amplifier architectures. A four-stage pseudo-differential amplifier with CMFF and CMFB is designed in a 1.2 V, 65-nm CMOS process. With NMCNR, it achieves a phase margin (PM) of 59° with a DC gain of 75 dB and unity-gain frequency (fug) of 712 MHz. With RNIC, the same four-stage amplifier achieves a phase margin of 84°, DC gain of 76 dB and fug of 2 GHz. Further, a three-stage single-ended amplifier is designed in a 1.1-V, 40-nm CMOS process. The three-stage OTA with RNIC achieves PM of 81°, DC gain of 80 dB and fug of 770 MHz. The same OTA achieves PM of 59° with NMCNR, while maintaining a DC gain of 75 dB and fug of 262 MHz. Pole-splitting, to achieve increased stability, is illustrated for both compensation schemes. Simulations illustrate that the RNIC scheme achieves much higher PM and fug for lower values of compensation capacitance compared to NMCNR, despite the growing number of low voltage amplifier stages.

  • 281.
    Ahmed, Ali
    Linköping University, Department of Computer and Information Science, Human-Centered systems. Linköping University, The Institute of Technology.
    A Systematic Literature Review of "Usability Inspection Methods"2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Objective: Usability inspection methods are a class of usability evaluation methods, applied by usability evaluators to assess usability related aspects of different user interfaces. Different usability inspection methods are proposed so far to evaluate user interfaces in a better way. This systematic literature review summarized different usability evaluation methods, with more focus on two widely used inspection methods. The review also summarized the problems with these two methods and probable proposed solution to cope with these problems.

    Method: A systematic review method as described by Kitchenham [3] was followed to carry out this review. The identified problems in the review were structured in a form of questions. The search to find the relevant data that address the identified questions were conducted on the basis of planned search strategies. Papers were selected on the basis of inclusion and exclusion criteria in accordance with the quality checklist; followed by data extraction and synthesis strictly characterized by quality checklist, inclusion and exclusion criteria to attain better results.

    Results and discussion: Despite of its advantages there still exists many weaknesses in Heuristic evaluation (HE) and Cognitive walk-through (CW) methods. Different studies have highlighted different factors that may influence the results. Those factors include number of evaluators, evaluator’s perception and experience, time, environment, cost, indigenous design, the way method applied and acquired software.

    Conclusion: To get better evaluation results, it is best to use different techniques for usability evaluation of single software or optimize existing techniques.

  • 282.
    Ahmed, Tanvir
    et al.
    Linköping University, Department of Electrical Engineering. Linköping University, Faculty of Science & Engineering.
    Garrido, Mario
    Linköping University, Department of Electrical Engineering, Electronics System. Linköping University, The Institute of Technology.
    Gustafsson, Oscar
    Linköping University, Department of Electrical Engineering, Electronics System. Linköping University, The Institute of Technology.
    A 512-point 8-parallel pipelined feedforward FFT for WPAN2011In: 2011 Conference Record of the Forty Fifth Asilomar Conference on Signals, Systems and Computers (ASILOMAR), IEEE , 2011, 981-984 p.Conference paper (Refereed)
    Abstract [en]

    This paper presents a 512-point feedforward FFT architecture for wireless personal area network (WPAN). The architecture processes a continuous flow of 8 samples in parallel, leading to a throughput of 2.64 GSamples/s. The FFT is computed in three stages that use radix-8 butterflies. This radix reduces significantly the number of rotators with respect to previous approaches based on radix-2. Besides, the proposed architecture uses the minimum memory that is required for a 512-point 8-parallel FFT. Experimental results show that besides its high throughput, the design is efficient in area and power consumption, improving the results of previous approaches. Specifically, for a wordlength of 16 bits, the proposed design consumes 61.5 mW and its area is 1.43 mm2.

  • 283.
    Ahmed, Zubair
    Linköping University, Department of Electrical Engineering, Electronics System. Linköping University, The Institute of Technology.
    Design of Autonomous Low Power Sensor for Soil Moisture Measurement.2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Drought is the most severe disaster compared to other disasters in human civilization and their impacts are serious which can cause hungur, thrist, food shortages, loss of livestock directly effects the human life. The main objective of this project is to develop an early warning system (EWS) [3] for drought indices by using wireless sensor networks (WSNs) which is the only way forward for an on-site monitoring and validation of locally defined drought indices [3].The designed wireless sensor network (WSN) consisting of a sensor unit, a master unit and a sensor power management unit (PMU). The sensor unit measures the moisture of the soil and transmitt the measured data through ZigBee module to the master unit. A real time clock (RTC) is also used in the sensor unit which records the information of second, minute, hour, day, month of day and year about when or what time the measurement taken. The master unit consisting of a SD-card and Bluetooth module. SD-card is used to store measured data from other sensor units and it is possible to take out the reading of measured data from the master unit by accessing the SD-card via Bluetooth inside the master unit to a PC or a smartphone mobile.To manage the power in the sensor unit and to make sensor alive for several years, the power management unit (PMU) manages the power level between two energy storage buffers (i.e., a supercapacitor and a Li+ ion battery) for a sensor node.

  • 284.
    Ahn, Henrik Casimir
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Thoracic Surgery. Östergötlands Läns Landsting, Heart Centre, Department of Thoracic and Vascular Surgery.
    Jodal, M.
    Lindhagen, J
    Lundgren, O.
    Nilsson, Gert
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Salerud, Göran
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Bestämning av tunntarmsblodflödet med laser Doppler teknik1984In: Läkarsällskapets Riksstämma,1984, 1984Conference paper (Other academic)
  • 285.
    Ahn, Henrik Casimir
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Thoracic Surgery. Östergötlands Läns Landsting, Heart Centre, Department of Thoracic and Vascular Surgery.
    Johansson, K.
    Lindhagen, J.
    Nilsson, Gert
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Salerud, Göran
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Förändringar av blodflödet i ventrikeln i samband med mätt med laser Dopplerteknik1984In: Läkarsällskapets Riksstämma,1984, 1984Conference paper (Other academic)
  • 286.
    Ahn, Henrik Casimir
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Thoracic Surgery. Östergötlands Läns Landsting, Heart Centre, Department of Thoracic and Vascular Surgery.
    Johansson, K.
    Lindhagen, J.
    Salerud, Göran
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Laser Doppler flowmetry in the assessment of gastric blood flow1984In: man. Scand J of Gastroenterology,1984, 1984, 98:33-98:33 p.Conference paper (Other academic)
  • 287.
    Ahn, Henrik Casimir
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Thoracic Surgery. Östergötlands Läns Landsting, Heart Centre, Department of Thoracic and Vascular Surgery.
    Lindhagen, J.
    Nilsson, Gert
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Salerud, Göran
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Jodal, M.
    Lundgren, O.
    Evaluation of Laser Doppler Flowmetry in the assessment of blood flow in the small intestine1984In: Third World Congress of Microcirculation,1984, 1984Conference paper (Other academic)
  • 288.
    Ahn, Henrik Casimir
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Thoracic Surgery. Östergötlands Läns Landsting, Heart Centre, Department of Thoracic and Vascular Surgery.
    Lindhagen, J
    Nilsson, Gert
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Salerud, Göran
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Jodal, M
    Lundgren, O
    Evaluation of Laser Doppler Flowmetry in the assessment of intestinal blood flow1985In: Gastroenterology, ISSN 0016-5085, E-ISSN 1528-0012, Vol. 4, no 88, 951-957 p.Article in journal (Refereed)
    Abstract [en]

      

  • 289.
    Ahola, David
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Yin To, Jie
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    To be entered/Green Cargo2013Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Schemakonstruktion för järnvägspersonal är en stor utmaning. En orsak är att arbetsuppgifterna vid järnvägen kräver olika kunskaps- och kompetenskrav, samt att det finns många arbetsregler som utgör restriktioner för schemakonstruktionen. I detta examensarbete har en fallstudie utförts för datorstödd schemakonstruktion för personalbemanning. Examensarbetet har utförts vid avdelningen för bemanningsplanering som ansvarar för planering av personal vid två av Green Cargos olika bangårdar. Huvudsyftet med det här examensarbetet är att utreda skillnaderna i scheman som skapats manuellt respektive automatiskt med hjälp av programvaran BP. Schemajämförelserna ska också redovisa nyttan av det automatiska planeringssättet där det finns applicerat. Under arbetet genomfördes litteraturstudier samt en fallstudie. I fallstudien genomfördes testkörningar med olika schemakonstruktionsmetoder på två bangårdar. Det numeriska resultatet visar att den datorassisterade bemanningsmetoden innebär en förbättrad bemanningsplanering ur företagets synvinkel då produktionsbehovet kan täckas utan ökade kostnader. Detta innebär också en ökad flexibilitet i produktionsplaneringen då tjänstgöringsturer enkelt kan ändras. Det gör det också mycket enklare att tilldela personal olika arbetsuppgifter som de har kompetens för. Den optimeringsbaserade bemanningsplanen innebär inte en ökad arbetsbelastning för medarbetaren. Trots att fler bangårdstjänster kan bemannas genom att använda den datorassisterade metoden visar det sig att den totala utlagda arbetstiden inte alls ökar eller att den bara ökar marginellt för vissa medarbetare. När planering sker med programvaran styrs denna av parametrar som är lätta att ändra. Dessa inställningar av parametrar är avgörande för utseendet på schemat. Indata kan vara fridagsplanering, kompetenstillgång och produktionsbehov. De i sin tur avgör i betydande grad på hur balansen mellan livs- och ekonomiska kvalitetsmåtten ser ut för medarbetarna.

  • 290.
    Ahrenberg, Lars
    Linköping University, Department of Computer and Information Science, NLPLAB - Natural Language Processing Laboratory. Linköping University, The Institute of Technology.
    A Simple Hybrid Aligner for Generating Lexical Correspondences in Parallel Texts.1998In: Proceedings of the 36th Annual Meeting of the Association for Computational Linguistics and 17th International Conference on Computational Linguistics (COLING-ACL'98) / [ed] Pierre Isabelle, Stroudsburg, PA, USA: The Association for Computational Linguistics , 1998, 29-35 p.Conference paper (Refereed)
  • 291.
    Ahrenberg, Lars
    Linköping University, Department of Computer and Information Science, NLPLAB - Natural Language Processing Laboratory. Linköping University, The Institute of Technology.
    Alignment-based profiling of Europarl data in an English-Swedish parallel corpus2010In: Proceedings of the Seventh conference on International Language Resources and Evaluation (LREC'10) / [ed] Nicoletta Calzolari (Conference Chair) and Khalid Choukri and Bente Maegaard and Joseph Mariani and Jan Odijk and Stelios Piperidis and Mike Rosner and Daniel Tapias, Paris, France: European Language Resources Association (ELRA) , 2010, 3398-3404 p.Conference paper (Refereed)
    Abstract [en]

    This paper profiles the Europarl part of an English-Swedish parallel corpus and compares it with three other subcorpora of the sameparallel corpus. We first describe our method for comparison which is based on alignments, both at the token level and the structurallevel. Although two of the other subcorpora contains fiction, it is found that the Europarl part is the one having the highest proportion ofmany types of restructurings, including additions, deletions and long distance reorderings. We explain this by the fact that the majorityof Europarl segments are parallel translations.

  • 292.
    Ahrenberg, Lars
    Linköping University, Department of Computer and Information Science, NLPLAB - Natural Language Processing Laboratory. Linköping University, The Institute of Technology.
    Automatisk textanalys i språkprofessionerna1999In: Samtal och språkanvändning i professionerna: Rapport från ASLA:s höstsymposium, Linköping, 6-7 november 1997 / [ed] Per Linell, Lars Ahrenberg, Linda Jönsson, Uppsala: ASLA , 1999, 19-32 p.Conference paper (Other academic)
  • 293.
    Ahrenberg, Lars
    Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, NLPLAB - Natural Language Processing Laboratory.
    Codified Close Translation as a Standard for MT2005In: Conference of the European Association for Machine Translation,2005, Budapest: EAMT , 2005, 13- p.Conference paper (Refereed)
  • 294.
    Ahrenberg, Lars
    Linköping University, Department of Computer and Information Science, NLPLAB - Natural Language Processing Laboratory. Linköping University, The Institute of Technology.
    LinES: An English-Swedish Parallel Treebank2007In: Proceedings of 16th Nordic Conference of Computational Linguistics Nodalida,2007 / [ed] Joakim Nivre, Heiki-Jaan Kaalep, Kadri Muischnek, Mare Koit, Tartu, Estonia: University of Tartu , 2007, 270-273 p.Conference paper (Refereed)
    Abstract [en]

    This paper presents an English-Swedish Parallel Treebank, LinES, that is currently under development. LinES is intended as a resource for the study of variation in translation of common syntactic constructions from English to Swedish. For this reason, annotation in LinES is syntactically oriented, multi-level, complete and manually reviewed according to guidelines. Another aim of LinES is to support queries made in terms of types of translation shifts.

  • 295.
    Ahrenberg, Lars
    Linköping University, Department of Computer and Information Science, NLPLAB - Natural Language Processing Laboratory. Linköping University, The Institute of Technology.
    Positions vs. precedences as primitives of constituent order1999In: Saetningsskemaet i Generativ Grammatik / [ed] Per Anker Jensen og Peter Skadhauge, Kolding: Institut for Erhvervssproglig Informatik og Kommunikation, Syddansk Universitet , 1999, 1-30 p.Chapter in book (Other academic)
  • 296.
    Ahrenberg, Lars
    Linköping University, Department of Computer and Information Science, NLPLAB - Natural Language Processing Laboratory. Linköping University, The Institute of Technology.
    Precedenser eller positioner för beskrivningen av svenskans ledföljd.1999In: Svenskans beskrivning 23: Förhandlingar vid Tjugotredje sammankomsten för svenskans beskrivning / [ed] Lars-Gunnar Andersson, Aina Lundqvist, Kerstin Norén, Lena Rogström, Lund: Lund University Press , 1999, 19-27 p.Conference paper (Other academic)
  • 297.
    Ahrenberg, Lars
    Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, NLPLAB - Natural Language Processing Laboratory.
    Searching Parallel Treebanks for Translation Relations2008In: Resourceful Language Technology: Festschrift in Honor of Anna Sågvall Hein, Uppsala: Acta Universitatis Upsaliensis , 2008, 1, 11-20 p.Chapter in book (Other academic)
    Abstract [en]

    As the first holder of the first chair in computational linguistics in Sweden, Anna Sågvall Hein has played a central role in the development of computational linguistics and language technology both in Sweden and on the international scene. Besides her valuable contributions to research, which include work on machine translation, syntactic parsing, grammar checking, word prediction, and corpus linguistics, she has been instrumental in establishing a national graduate school in language technology as well as an undergraduate program in language technology at Uppsala University. It is with great pleasure that we present her with this Festschrift to honor her lasting contributions to the field and to commemorate her retirement from the chair in computational linguistics at Uppsala University. The contributions to the Festschrift come from Anna’s friends and colleagues around the world and deal with many of the topics that are dear to her heart. A common theme in many of the articles, as well as in Anna’s own scientific work, is the design, development and use of adequate language technology resources, epitomized in the title Resourceful Language Technology.

  • 298.
    Ahrenberg, Lars
    et al.
    Linköping University, Department of Computer and Information Science, NLPLAB - Natural Language Processing Laboratory. Linköping University, The Institute of Technology.
    Andersson, Mikael
    Linköping University.
    Merkel, Magnus
    Linköping University, Department of Computer and Information Science, NLPLAB - Natural Language Processing Laboratory. Linköping University, The Institute of Technology.
    A Simple Hybrid Aligner for Generating Lexical Correspondences in Parallel Texts1998In: Proceedings of the 36th Annual Meeting of the Association for Computational Linguistics and 17th International Conference on Computational Linguistics (COLING-ACL'98) Montreal, August 10-14, 1998, / [ed] Pierre Isabelle, The Association for Computational Linguistics , 1998, 29-35 p.Conference paper (Refereed)
  • 299.
    Ahrenberg, Lars
    et al.
    Linköping University, Department of Computer and Information Science, NLPLAB - Natural Language Processing Laboratory. Linköping University, The Institute of Technology.
    Andersson, Mikael
    Merkel, Magnus
    Linköping University, Department of Computer and Information Science, NLPLAB - Natural Language Processing Laboratory. Linköping University, The Institute of Technology.
    A System for Incremental and Interactive Word Linking2002In: In Third International Conference on Language Resources and Evaluation (LREC 2002), Las Palmas, 29-31 May 2002., European Language Resources Association (ELRA) , 2002, 485-490 p.Conference paper (Refereed)
    Abstract [en]

    Aligned parallel corpora constitute a critical information resource for a great number of linguistic and technological endeavors. Automatic sentence alignment has reached a level whereby large parallel documents can be fully aligned with the aid of interactive post-editing tools. Word alignment systems have not yet reached the same level of performance, but are good enough to support full word alignment if embedded in an interactive system. In this paper we describe a system for fast and accurate word alignment currently under development at our department, where the user can review and improve the output from an automatic system in an incremental fashion.

  • 300.
    Ahrenberg, Lars
    et al.
    Linköping University, Department of Computer and Information Science, NLPLAB - Natural Language Processing Laboratory. Linköping University, The Institute of Technology.
    Dahlbäck, Nils
    Linköping University, Department of Computer and Information Science, CSELAB - Cognitive Systems Engineering Laboratory. Linköping University, The Institute of Technology.
    Thureé, Åke
    Linköping University.
    Jönsson, Arne
    Linköping University, Department of Computer and Information Science, NLPLAB - Natural Language Processing Laboratory. Linköping University, The Institute of Technology.
    Customizing Interaction for Natural Language Interfaces1996Report (Other academic)
3456789 251 - 300 of 28828
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