| 1. |
- Agrell, Per J., et al.
(författare)
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A Coherent Methodology for Productivity Analysis Employing Integrated Partial Efficiency
- 1996
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Ingår i: International Journal of Production Economics. - 0925-5273 .- 1873-7579. ; 46-47, s. 401-411
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Tidskriftsartikel (refereegranskat)abstract
- An activity decomposition methodology with theoretical foundation in the principles of activity control and stated focus of interest in the enterprise value-chain is presented. Characteristics of inputs and outputs are discussed, where a set of non-transformable inputs are defined and motivated. An integrated partial efficiency measure is formulated, compensating for some weaknesses of the Debreu-Farrell technical efficiency concept. Providing a coherent basis for productivity analysis, the IPE approach poses an alternative to e.g. DEA especially in the case of multi-level systems and sparse data. The method is easily communicable in terms of measurement and analysis, and may be extended to complement economic performance assessments and benchmarks.
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| 2. |
- Agrell, Per, J., et al.
(författare)
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An MCDM Framework for Dynamic Systems
- 1996
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Ingår i: International Journal of Production Economics. - : Elsevier BV. - 0925-5273 .- 1873-7579. ; 45:1-3, s. 279-292
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Tidskriftsartikel (refereegranskat)abstract
- A multi-criteria formulation for continuous and discrete-time dynamic systems is presented. The fundamental problem in the design of dynamic systems is the trade-off between response speed (e.g., the time to reach final value and the raise time) and response smoothness (e.g., the overshoot, the undershoot, and the transient dampening). Separate optimisation of criteria is impossible, thus the problem is inherently multiobjective. In a general dynamic system, this is accomplished by adjusting a number of technical parameters in accordance with some ad hoc practice. Previous multi-criteria approaches have been modelled as weighted sums of criteria, with shortcomings in terms of sensitivity analysis and preference articulation. The proposed framework enables the decision maker to design a most preferred system, with full knowledge of local trade-off ratios in terms of chosen criteria. Combining analytical techniques with simulation, the formulation makes the optimisation process transparent to the decision maker, working entirely in decision space. The framework is demonstrated on a dynamic production-inventory model.
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| 3. |
- Ahlgren, Joakim, et al.
(författare)
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Orsaker till minskande syrehalter i Bottenhavet
- 2017
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Rapport (refereegranskat)abstract
- Resultat från den nationella miljöövervakningen visar att syrehalterna i Bottenhavet har minskat sedan 1970-talet, en minskning som accelererat från 1990. För att ha möjlighet att på något sätt kunna åtgärda denna försämring av den marina miljön är det nödvändigt att identifiera orsakerna till denna syreminskning, eftersom olika orsaker kan kräva olika former av åtgärder. Om orsaken till exempel är ökad syreförbrukning beroende på regional övergödning, skulle detta innebära ökat behov av regionala reningsåtgärder. Målsättningen med projektet var därmed att ge en tillförlitlig förklaring till de sjunkande syrehalterna i Bottenhavet under de senaste 20 åren genom att använda data från de nationella miljöövervakningsprogrammen. De huvudhypoteser som undersöktes som orsaker till de sjunkande syrehalterna var: • Ökad regional gödning av Bottenhavet och därmed ökad produktion. • Tillförsel av syrefattigt och fosfatrikt från Egentliga Östersjön. • Starkare haloklin och försämrad ventilation av Bottenhavets djupvatten. • Ökad temperatur och ökad tillförsel av löst organiskt kol. Analys av tidsserier och modellanalyser utifrån miljöövervaknings- och forskningsdata visade att den observerade syrehaltsminskningen i Bottenhavets djupvatten främst beror på en ökning av vattentemperaturen och delvis på en ökning av löst organiskt kol i vattnet, samt tillflöde från Egentliga Östersjön. Dataanalysen visade däremot inget tydligt stöd för att ökad produktion av biomassa i Bottenhavet orsakat de minskande syrehalterna. Detta gäller indikatorer för växtplankton, sedimentation och bakterieplankton som alla förväntas öka vid ökad produktion och det finns således inga direkta indicier för att stödja hypotesen om ökad gödning av Bottenhavet. Sammantaget visar de analyser som gjorts inom projektet att Bottenhavets framtida hälsa främst gynnas av en kombination av åtgärder för att motverka globala klimatförändringar, samt åtgärder för att förbättra vattenkvaliteten i Egentliga Östersjön. Näringstillförsel från Bottenhavets avrinningsområden bedöms främst ha haft betydelse för syresituationen i kustnära vattenförekomster. Den bedöms därför inte i betydande omfattning ha orsakat de minskande syrehalterna i Bottenhavets utsjöområden.
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| 4. |
- Ahlgren, Joakim, et al.
(författare)
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Temperature, DOC level and basin interactions explain the declining oxygen concentrations in the Bothnian Sea
- 2017
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Ingår i: Journal of Marine Systems. - : Elsevier BV. - 0924-7963 .- 1879-1573. ; 170, s. 22-30
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Tidskriftsartikel (refereegranskat)abstract
- Hypoxia and oxygen deficient zones are expanding worldwide. To properly manage this deterioration of the marine environment, it is important to identify the causes of oxygen declines and the influence of anthropogenic activities. Here, we provide a study aiming to explain the declining oxygen levels in the deep waters of the Bothnian Sea over the past 20 years by investigating data from environmental monitoring programmes. The observed decline in oxygen concentrations in deep waters was found to be primarily a consequence of water temperature increase and partly caused by an increase in dissolved organic carbon (DOC) in the seawater (R-Adj(2). = 0.83) as well as inflow from the adjacent sea basin. As none of the tested eutrophication-related predictors were significant according to a stepwise multiple regression, a regional increase in nutrient inputs to the area is unlikely to explain a significant portion of the oxygen decline. Based on the findings of this study, preventing the development of anoxia in the deep water of the Bothnian Sea is dependent on the large-scale measures taken to reduce climate change. In addition, the reduction of the nutrient load to the Baltic Proper is required to counteract the development of hypoxic and phosphate-rich water in the Baltic Proper, which can form deep water in the Bothnian Sea. The relative importance of these sources to oxygen consumption is difficult to determine from the available data, but the results clearly demonstrate the importance of climate related factors such as temperature, DOC and inflow from adjacent basins for the oxygen status of the sea.
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| 5. |
- Alvbrant, Joakim, 1973-
(författare)
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A study on emerging electronics for systems accepting soft errors
- 2016
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Moore’s law has until today mostly relied on shrinkage of the size of the devices inintegrated circuits. However, soon the granularity of the atoms will set a limit together with increased error probability of the devices. How can Moore’s law continue in thefuture? To overcome the increased error rate, we need to introduce redundancy. Applyingmethods from biology may be a way forward, using some of the strategies that transformsan egg into a fetus, but with electronic cells.A redundant system is less sensitive to failing components. We define electronic clayas a massive redundancy system of interchangeable and unified subsystems. We show how a mean voter, which is simpler than a majority voter, impact a redundant systemand how optimization can be formalized to minimize the impact of failing subsystems.The performance at given yield can be estimated with a first order model, without the need for Monte-Carlo simulations. The methods are applied and verified on a redundant finite-impulse response filter.The elementary circuit behavior of the memristor, ”the missing circuit element”, is investigated for fundamental understanding and how it can be used in applications. Different available simulation models are presented and the linear drift model is simulated with Joglekar-Wolf and Biolek window functions. Driven by a sinusoidal current, the memristor is a frequency dependent component with a cut-off frequency. The memristor can be densely packed and used in structures that both stores and compute in the same circuit, as neurons do. Surrounding circuit has to affect (write) and react (read) to the memristor with the same two terminals.We looked at artificial neural network for pattern recognition, but also for self organization in electronic cell array. Finally we look at wireless sensor network and how such system can adopt to the environment. This is also a massive redundant clay-like system.Future electronic systems will be massively redundant and adaptive. Moore’s law will continue, not based on shrinking device sizes, but on cheaper, numerous, unified and interchangeable subsystems.
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| 6. |
- Alvbrant, Joakim, 1973-, et al.
(författare)
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Study and Simulation Example of a Redundant FIR Filter
- 2012
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Ingår i: Proceedings 30th Norchip Conference. - : IEEE. - 9781467322225 - 9781467322218 ; , s. 1-4
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Konferensbidrag (refereegranskat)abstract
- In this paper we present a study and simulation results of the structure and design of a redundant finite-impulse response (FIR) filter. The filter has been selected as an illustrative example for biologically-inspired circuits, but the structure can be generalized to cover other signal processing systems. In the presented study, we elaborate on signal processing properties of the filter if we apply a redundant architecture were different computing paths can be utilized. An option is to utilize different computing paths as inspired by biological architectures (BIAs). We present typical simulation results for a low-pass filter illustrating the trade-offs and costs associated with this architecture.
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| 7. |
- Alvbrant, Joakim, et al.
(författare)
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Transfer Characteristics and Bandwidth Limitation in a Linear-Drift Memristor Model
- 2015
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Ingår i: 2015 EUROPEAN CONFERENCE ON CIRCUIT THEORY AND DESIGN (ECCTD). - : IEEE. - 9781479998777 ; , s. 332-335
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Konferensbidrag (refereegranskat)abstract
- The linear-drift memristor model, suggested by HP Labs a few years ago, is used in this work together with two window functions. From the equations describing the memristor model, the transfer characteristics of a memristor is formulated and analyzed. A first-order estimation of the cut-off frequency is shown, that illustrates the bandwidth limitation of the memristor and how it varies with some of its physical parameters. The design space is elaborated upon and it is shown that the state speed, the variation of the doped and undoped regions of the memristor, is inversely proportional to the physical length, and depth of the device. The transfer characteristics is simulated for Joglekar-Wolf, and Biolek window functions and the results are analyzed. The Joglekar-Wolf window function causes a distinct behavior in the tranfer characteristics at cut-off frequency. The Biolek window function on the other hand gives a smooth state transfer function, at the cost of loosing the one-to-one mapping between charge and state. We also elaborate on the design constraints derived from the transfer characteristics.
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| 8. |
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| 9. |
- Bäckstrand, Jenny
(författare)
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A Method for Customer-driven Purchasing : Aligning Supplier interaction and Customer-driven manufacturing
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The role of a purchaser has traditionally focused on acquiring standard items at the lowest possible cost. The ability to reduce unit cost has been the key performance indicator for purchasers. Most traditional purchasing strategies thus focus on optimizing this situation, focusing on the supplier interface only and not on customer value. However, for many manufacturing companies, the demand from their customers has changed lately. Not only low‐cost standard products but also customized products and short delivery lead times is increasingly required. In order to contribute to the focal actor’s competitiveness, purchasers need a purchasing strategy that supports customer value creation and thus differentiates between acquiring standard items and acquiring customized items. Accordingly, not only the focal actor’s interaction with the supplier needs to be regarded in the purchasing situation, but also the interaction with the focal actor’s customer. This is defined as customer‐driven purchasing in this research.The purpose of this research is to develop knowledge that contributes to increased competitiveness of manufacturing companies. The manufacturer can increase competitiveness by further utilizing knowledge available in manufacturing strategy in the purchasing situation. The main objective of this dissertation is to analyze the competitiveness in customer‐driven purchasing and to develop a method for customerdriven purchasing by aligning supplier interaction with customer‐driven manufacturing. The method for customer‐driven purchasing (the CDP method) was developed in collaboration with Combitech AB, Ericsson AB, Fagerhult AB, Husqvarna AB, Parker Hannifin AB, and Siemens Turbomachinery AB. The CDP method consists of three phases, divided into twelve steps. The first phase focuses on identifying strategic lead times and differentiating between varying circumstances for the purchased items. The second phase focuses on analyzing customer‐driven manufacturing while the third phase focuses on analyzing supplier interaction. The method is concluded with the implementation of customer‐driven purchasing.When applying the three phases of the CDP method, the case companies have experienced a better alignment between customer expectations and supplier performance since the competitive priorities to pursue in a supplier interaction are identified and taken action upon. Direct visible results of implementing the model are, for example, shortened supply lead time for customized items, and reduced inventory levels for standard items. The CDP method has also helped the companies to identify critical suppliers and how the supplier interaction should be affected by the customer demand for the purchased item. Several indirect results have also been reported, such as, improved internal communication, and a better balance between short supply lead time and low cost. Thus the need to differentiate and balance the goals and key performance indicators for purchasers has become evident. Applying the CDP method has been seen as an important learning process in which the objectives of purchasing and manufacturing are aligned for improved competitiveness. This contributes to establishing purchasing as a strategically important competitive function and to support a holistic view of the focal actor’s competitiveness.
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| 10. |
- Bäckstrand, Jenny, 1979-, et al.
(författare)
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A method for customer-driven purchasing
- 2013
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Ingår i: Operations Management at the Heart of the Recovery. - : International Annual EurOMA Conference.
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Konferensbidrag (refereegranskat)
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