| 1. |
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| 2. |
- Pajala, Gustav, et al.
(författare)
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The effects of water column dissolved oxygen concentrations on lake methane emissions : results from a whole-lake oxygenation experiment
- 2023
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Ingår i: Journal of Geophysical Research - Biogeosciences. - : American Geophysical Union (AGU). - 2169-8953 .- 2169-8961. ; 128:11
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Tidskriftsartikel (refereegranskat)abstract
- Lakes contribute 9%–19% of global methane (CH4) emissions to the atmosphere. Dissolved molecular oxygen (DO) in lakes can inhibit the production of CH4 and promote CH4 oxidation. DO is therefore often considered an important regulator of CH4 emissions from lakes. Presence or absence of DO in the water above the sediments can affect CH4 production and emissions by (a) influencing if methane production can be fueled by the most reactive organic matter in the top sediment layer or rely on deeper and less degradable organic matter, and (b) enabling CH4 accumulation in deep waters and potentially large emissions upon water column turnover. However, the relative importance of these two DO effects on CH4 fluxes is still unclear. We assessed CH4 fluxes from two connected lake basins in northern boreal Sweden where one was experimentally oxygenated. Results showed no clear difference in summer CH4 emissions attributable to water column DO concentrations. Large amounts of CH4 accumulated in the anoxic hypolimnion of the reference basin but little of this may have been emitted because of incomplete mixing, and effective methane oxidation of stored CH4 reaching oxic water layers. Accordingly, ≤24% of the stored CH4 was likely emitted in the experimental lake. Overall, our results suggest that hypolimnetic DO and water column CH4 storage might have a smaller impact on CH4 emissions in boreal forest lakes than previous estimates, yet potential fluxes associated with water column turnover events remain a significant uncertainty in lake CH4 emission estimates.
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| 3. |
- Pajala, Gustav, et al.
(författare)
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Higher apparent gas transfer velocities for CO2 compared to CH4 in small lakes
- 2023
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Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 57:23, s. 8578-8587
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Tidskriftsartikel (refereegranskat)abstract
- Large greenhouse gas emissions occur via the release of carbon dioxide (CO2) and methane (CH4) from the surface layer of lakes. Such emissions are modeled from the air-water gas concentration gradient and the gas transfer velocity (k). The links between k and the physical properties of the gas and water have led to the development of methods to convert k between gases through Schmidt number normalization. However, recent observations have found that such normalization of apparent k estimates from field measurements can yield different results for CH4 and CO2. We estimated k for CO2 and CH4 from measurements of concentration gradients and fluxes in four contrasting lakes and found consistently higher (on an average 1.7 times) normalized apparent k values for CO2 than CH4. From these results, we infer that several gas-specific factors, including chemical and biological processes within the water surface microlayer, can influence apparent k estimates. We highlight the importance of accurately measuring relevant air-water gas concentration gradients and considering gas-specific processes when estimating k.
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| 4. |
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| 5. |
- Rudberg, David, et al.
(författare)
-
Contribution of gas concentration and transfer velocity to CO2 flux variability in northern lakes
- 2024
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Ingår i: Limnology and Oceanography. - : WILEY. - 0024-3590 .- 1939-5590.
-
Tidskriftsartikel (refereegranskat)abstract
- The CO( 2)flux (FCO2) from lakes to the atmosphere is a large component of the global carbon cycle anddepends on the air-water CO2concentration gradient (Delta CO2) and the gas transfer velocity (k). Both Delta CO2 and k can vary on multiple timescales and understanding their contributions toFCO(2)is important for explaining var-iability influxes and developing optimal sampling designs. We measuredFCO2 and Delta CO(2 )and derivedkforone full ice-free period in 18 lakes usingfloating chambers and estimated the contributions of Delta CO2 and k to FCO2 variability. Generally, kcontributed more than Delta CO2to short-term (1-9d) FCO2 variability. With in creased temporal period, the contribution of k to FCO2 variability decreased, and in some lakes resulted in Delta CO2 contrib-uting more thank to FCO2 variability over the full ice-free period. Increased contribution of Delta CO2 to FCO2 vari-ability over time occurred across all lakes but was most apparent in large-volume southern-boreal lakes and indeeper (>2m) parts of lakes, whereaskwas linked to FCO(2 )variability in shallow waters. Accordingly, knowing the variability of bothk and Delta CO(2 )over time and space is needed for accurate modeling of F CO2 from these vari-ables. We conclude that priority in FCO(2 )assessments should be given to direct measurements of FCO2 at multiplesites when possible, or otherwise from spatially distributed measurements of Delta CO(2 )combined with k- models that incorporate spatial variability of lake thermal structure and meteorology.
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| 6. |
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| 7. |
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| 8. |
- Antonucci, Alessandro, et al.
(författare)
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Decision Making with Hierarchical Credal Sets
- 2014
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Ingår i: Information Processing and Management of Uncertainty in Knowledge-Based Systems. - Cham : Springer. - 9783319088518 - 9783319088525 ; , s. 456-465
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Konferensbidrag (refereegranskat)abstract
- We elaborate on hierarchical credal sets, which are sets of probability mass functions paired with second-order distributions. A new criterion to make decisions based on these models is proposed. This is achieved by sampling from the set of mass functions and considering the Kullback-Leibler divergence from the weighted center of mass of the set. We evaluate this criterion in a simple classification scenario: the results show performance improvements when compared to a credal classifier where the second-order distribution is not taken into account.
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| 9. |
- Bastviken, David, et al.
(författare)
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Critical method needs in measuring greenhouse gas fluxes
- 2022
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Ingår i: Environmental Research Letters. - : IOP Publishing Ltd. - 1748-9326. ; 17:10
-
Tidskriftsartikel (refereegranskat)abstract
- Reaching climate goals depends on appropriate and accurate methods to quantify greenhouse gas (GHG) fluxes and to verify that efforts to mitigate GHG emissions are effective. We here highlight critical advantages, limitations, and needs regarding GHG flux measurement methods, identified from an analysis of >13 500 scientific publications regarding three long-lived GHGs, carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O). While existing methods are well-suited for assessing atmospheric changes and local fluxes, they are expensive and have limited accessibility. Further, we are typically forced to choose between methods for very local GHG sources and sinks and their regulation (m(2)-scaled measurements), or methods for aggregated net fluxes at >ha or km(2) scales measurements. The results highlight the key need of accessible and affordable GHG flux measurement methods for the many flux types not quantifiable from fossil fuel use, to better verify inventories and mitigation efforts for transparency and accountability under the Paris agreement. The situation also calls for novel methods, capable of quantifying large scale GHG flux patterns while simultaneously distinguishing local source and sink dynamics and reveal flux regulation, representing key knowledge for quantitative GHG flux modeling. Possible strategies to address the identified GHG flux measurement method needs are discussed. The analysis also generated indications of how GHG flux measurements have been distributed geographically and across flux types, which are reported.
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| 10. |
- Bastviken, David, Professor, 1971-, et al.
(författare)
-
Measuring greenhouse gas fluxes : what methods do we have versus what methods do we need?
- 2022
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Appropriate methods to measure greenhouse gas (GHG) fluxes are critical for our ability to detect fluxes, understand regulation, make adequate priorities for climate change mitigation efforts, and verify that these efforts are effective. Ideally, we need reliable, accessible, and affordable measurements at relevant scales. We surveyed present GHG flux measurement methods, identified from an analysis of >11000 scientific publications and a questionnaire to sector professionals and analysed method pros and cons versus needs for novel methodology. While existing methods are well-suited for addressing certain questions, this presentation presents fundamental limitations relative to GHG flux measurement needs for verifiable and transparent action to mitigate many types of emissions. Cost and non-academic accessibility are key aspects, along with fundamental measurement performance. These method limitations contribute to the difficulties in verifying GHG mitigation efforts for transparency and accountability under the Paris agreement. Resolving this mismatch between method capacity and societal needs is urgently needed for effective climate mitigation. This type of methodological mismatch is common but seems to get high priority in other knowledge domains. The obvious need to prioritize development of accurate diagnosis methods for effective treatments in healthcare is one example. This presentation provides guidance regarding the need to prioritize the development of novel GHG flux measurement methods.
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| 11. |
- Bastviken, David, et al.
(författare)
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Technical Note: Cost-efficient approaches to measure carbon dioxide (CO2) fluxes and concentrations in terrestrial and aquatic environments using mini loggers
- 2015
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Ingår i: Biogeosciences. - : European Geosciences Union (EGU) / Copernicus Publications. - 1726-4170 .- 1726-4189. ; 12:12, s. 3849-3859
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Tidskriftsartikel (refereegranskat)abstract
- Fluxes of CO2 are important for our understanding of the global carbon cycle and greenhouse gas balances. Several significant CO2 fluxes in nature may still be unknown as illustrated by recent findings of high CO2 emissions from aquatic environments, previously not recognized in global carbon balances. Therefore, it is important to develop convenient and affordable ways to measure CO2 in many types of environments. At present, direct measurements of CO2 fluxes from soil or water, or CO2 concentrations in surface water, are typically labor intensive or require costly equipment. We here present an approach with measurement units based on small inexpensive CO2 loggers, originally made for indoor air quality monitoring, that were tested and adapted for field use. Measurements of soil-atmosphere and lake-atmosphere fluxes, as well as of spatiotemporal dynamics of water CO2 concentrations (expressed as the equivalent partial pressure, pCO(2aq)) in lakes and a stream network are provided as examples. Results from all these examples indicate that this approach can provide a cost- and labor-efficient alternative for direct measurements and monitoring of CO2 flux and pCO(2aq) in terrestrial and aquatic environments.
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| 12. |
- Danielson, Mats, et al.
(författare)
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Cross-disciplinary research in analytic decision support systems
- 2006
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Ingår i: ITI 2006. - Zagreb : University Computing Centre SRCE, University of Zagreb. - 9537138054 ; , s. 123-128
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Konferensbidrag (refereegranskat)abstract
- A main problem in nearly all contexts is that unguided decision making is tremendously difficult and can lead to inefficient decision processes and undesired consequences. Therefore, decision support systems (DSSs) are of prime concern to any organization and there have been numerous approaches to such from, e.g., computational, mathematical, financial, philosophical, psychological, and sociological angles. However, a key observation is that efficient decision making is not easily performed by using methods from one discipline only. The case is rather that if real world decision making is taken seriously, several aspects must be included. This article describes some efforts of the DECIDE research group for approaching decision making and developing DSSs in a cross-disciplinary environment.
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| 13. |
- Danielson, Mats, et al.
(författare)
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Cross-Disciplinary Research in Analytic Decision Support Systems
- 2006
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Ingår i: ITI 2006. - Zagreb : University Computing Centre SRCE, University of Zagreb. - 9537138054 ; , s. 123-128
-
Konferensbidrag (refereegranskat)abstract
- A main problem in decision support contexts is that unguided decision making is difficult and can lead to inefficient decision processes and undesired consequences. Therefore, decision support systems (DSSs) are of prime concern to any organization and there have been numerous approaches to delivering decision support from, e.g., computational, mathematical, financial, philosophical, psychological, and sociological angles. A key observation, however, is that effective and efficient decision making is not easily achieved by using methods from one discipline only. This paper describes some efforts made by the DECIDE Research Group to approach DSS development and decision making tools in a cross-disciplinary way.
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| 14. |
- Ekenberg, Love, et al.
(författare)
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Second-Order Risk Constraints in Decision Analysis
- 2014
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Ingår i: Axioms. - Basel : MDPI AG. - 2075-1680. ; 3:1, s. 31-45
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Tidskriftsartikel (refereegranskat)abstract
- Recently, representations and methods aimed at analysing decision problems where probabilities and values (utilities) are associated with distributions over them (second-order representations) have been suggested. In this paper we present an approach to how imprecise information can be modelled by means of second-order distributions and how a risk evaluation process can be elaborated by integrating procedures for numerically imprecise probabilities and utilities. We discuss some shortcomings of the use of the principle of maximising the expected utility and of utility theory in general, and offer remedies by the introduction of supplementary decision rules based on a concept of risk constraints taking advantage of second-order distributions.
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| 15. |
- Eriksson, Mats, 1963-, et al.
(författare)
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Drinking water monitoring with voltammetric sensors
- 2011
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Ingår i: Procedia Engineering. - : Elsevier. - 1877-7058. ; 25, s. 1165-1168
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Tidskriftsartikel (refereegranskat)abstract
- Pulsed voltammetry has been applied to drinking water monitoring. This non-selective technique facilitates detection of several different threats to the drinking water. A multivariate algorithm shows that anomaly detection is possible with a minimum of false alarms. Multivariate analysis can also be used to classify different types of substances added to the drinking water. Low concentrations of sewage water contaminating the drinking water can be detected. A network of such sensors is envisaged to facilitate real-time and on-line monitoring of drinking water distribution networks.
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| 16. |
- Eriksson, Mats, et al.
(författare)
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Event Detection in Crisis Management Systems
- 2009
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Ingår i: Procedia Chemistry. - : Elsevier. - 1876-6196. ; 1:1, s. 1055-1058
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Tidskriftsartikel (refereegranskat)abstract
- The EVENT project concerns drinking water surveillance and includes sensors and algorithms that detect anomalies in the drinking water properties, communication of the evaluated sensor data to a crises management system and presentation of information that is relevant for the end users of the crises management system. We have chosen to focus on a sensor technique based on an "electronic tongue", since this robust type of non-selective sensor, can detect a plurality of anomalies without the need of a specific sensor for each type of event. Measurements of natural variations and contamination events are presented and discussed.
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| 17. |
- G. Rázuri, Javier, et al.
(författare)
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Automatic Emotion Recognition through Facial Expression Analysis in Merged Images Based on an Artificial Neural Network
- 2013
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Ingår i: 2013 12th Mexican International Conference on Artificial Intelligence (MICAI). - : IEEE. - 9781479926046 - 9781479926053 ; , s. 85-96
-
Konferensbidrag (refereegranskat)abstract
- This paper focuses on a system of recognizing human’s emotion from a detected human’s face. The analyzed information is conveyed by the regions of the eye and the mouth into a merged new image in various facial expressions pertaining to six universal basic facial emotions. The output information obtained could be fed as an input to a machine capable to interact with social skills, in the context of building socially intelligent systems. The methodology uses a classification technique of information into a new fused image which is composed of two blocks integrated by the area of the eyes and mouth, very sensitive areas to changes human’s expression and that are particularly relevant for the decoding of emotional expressions. Finally we use the merged image as an input to a feed-forward neural network trained by back-propagation. Such analysis of merged images makes it possible, obtain relevant information through the combination of proper data in the same image and reduce the training set time while preserved classification rate. It is shown by experimental results that the proposed algorithm can detect emotion with good accuracy.
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| 18. |
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| 19. |
- Guerrero Rázuri, Javier, et al.
(författare)
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Effect of emotional feedback in a decision-making system for an autonomous agent
- 2014
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Ingår i: Advances in Artificial Intelligence - IBERAMIA 2014. - Cham : Springer. - 9783319120263 - 9783319120270 ; , s. 613-624
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Konferensbidrag (refereegranskat)abstract
- The point of view of Isaac Asimov is unlikely in a close future, but machines that develop tasks in a sensible manner are already a fact. In light of this remark, recent research tries to understand the requirements and design options that imply providing an autonomous agent with means for detecting emotions. If we think about of exporting this model to machines, it is possible that they become capable to evolve emotionally according to such models and would take part in the society more or less cooperatively, according to the perceived emotional state. The main purpose of this research is the implementation of a decision model affected by emotional feedback in a cognitive robotic assistant that can capture information about the world around it. The robot will use multi-modal communication to assist the societal participation of persons deprived of conventional modes of communication. The aim is a machine that can predict what the user will do next and be ready to give the best possible assistance, taking in account the emotional factor. The results indicate the benefits and importance of emotional feedback in the closed loop human-robot interaction framework. Cognitive agents are shown to be capable of adapting to emotional information from humans.
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| 20. |
- Guerrero Razuri, Javier Francisco, 1977-
(författare)
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Decisional-Emotional Support System for a Synthetic Agent : Influence of Emotions in Decision-Making Toward the Participation of Automata in Society
- 2015
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Emotion influences our actions, and this means that emotion has subjective decision value. Emotions, properly interpreted and understood, of those affected by decisions provide feedback to actions and, as such, serve as a basis for decisions. Accordingly, "affective computing" represents a wide range of technological opportunities toward the implementation of emotions to improve human-computer interaction, which also includes insights across a range of contexts of computational sciences into how we can design computer systems to communicate and recognize the emotional states provided by humans. Today, emotional systems such as software-only agents and embodied robots seem to improve every day at managing large volumes of information, and they remain emotionally incapable to read our feelings and react according to them. From a computational viewpoint, technology has made significant steps in determining how an emotional behavior model could be built; such a model is intended to be used for the purpose of intelligent assistance and support to humans. Human emotions are engines that allow people to generate useful responses to the current situation, taking into account the emotional states of others. Recovering the emotional cues emanating from the natural behavior of humans such as facial expressions and bodily kinetics could help to develop systems that allow recognition, interpretation, processing, simulation, and basing decisions on human emotions. Currently, there is a need to create emotional systems able to develop an emotional bond with users, reacting emotionally to encountered situations with the ability to help, assisting users to make their daily life easier. Handling emotions and their influence on decisions can improve the human-machine communication with a wider vision. The present thesis strives to provide an emotional architecture applicable for an agent, based on a group of decision-making models influenced by external emotional information provided by humans, acquired through a group of classification techniques from machine learning algorithms. The system can form positive bonds with the people it encounters when proceeding according to their emotional behavior. The agent embodied in the emotional architecture will interact with a user, facilitating their adoption in application areas such as caregiving to provide emotional support to the elderly. The agent's architecture uses an adversarial structure based on an Adversarial Risk Analysis framework with a decision analytic flavor that includes models forecasting a human's behavior and their impact on the surrounding environment. The agent perceives its environment and the actions performed by an individual, which constitute the resources needed to execute the agent's decision during the interaction. The agent's decision that is carried out from the adversarial structure is also affected by the information of emotional states provided by a classifiers-ensemble system, giving rise to a "decision with emotional connotation" included in the group of affective decisions. The performance of different well-known classifiers was compared in order to select the best result and build the ensemble system, based on feature selection methods that were introduced to predict the emotion. These methods are based on facial expression, bodily gestures, and speech, with satisfactory accuracy long before the final system.
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| 21. |
- Guerrero Rázuri, Javier Francisco, et al.
(författare)
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Integration of Artificial Neural Networks and Linear Systems for the Output Feedback Control of Nonlinear Vibration Systems
- 2014
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Ingår i: CCC 2014, the 33rd Chinese Control Conference. - : IEEE Press. ; , s. 1850-1855
-
Konferensbidrag (refereegranskat)abstract
- This paper analyzes the integration of neural networks and linear systems for the identification, state estimation and output feedback control of weakly nonlinear systems. Considering previous knowledge about the system given by approximated linear state-space models, linear observers and linear controllers, training algorithms for the neuro-identification, state neuro-estimation and output feedback neuro-control were derived considering the dynamics of the nonlinear system. It was found that the integrated linear-neuro model can identify the dynamics of the system much more accurately than a purely linear model or a purely neuro model. It was also found that the state estimation and vibration isolation performance of the system with integrated linear-neuro output feedback control is better than the system with linear control or neuro-control.
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| 22. |
- Guerrero Rázuri, Javier Francisco, et al.
(författare)
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Recognition of emotions by the emotional feedback through behavioral human poses
- 2015
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Ingår i: International Journal of Computer Science Issues. - 1694-0784 .- 1694-0814. ; 12:1, s. 7-17
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Tidskriftsartikel (refereegranskat)abstract
- The sensory perceptions from humans are intertwined channels,which assemble diverse data in order to decrypt emotionalinformation. Just by associations, humans can mix emotionalinformation, i.e. emotion detection through facial expressionscriteria, emotional speech, and the challenging field of emotionalbody language over the body poses and motion. In this work, wepresent an approach that can predict six basic universal emotionscollected by responses linked to human body poses, from acomputational perspective. The emotional outputs could be fedas inputs to a synthetic socially skilled agent capable ofinteraction, in the context of socially intelligent systems. Themethodology uses a classification technique of information fromsix images extracted from a video, entirely developed using themotion sensing input device of Xbox 360 by Microsoft. We aretaking into account that the emotional body language containsadvantageous information about the emotional state of humans,especially when bodily reaction brings about consciousemotional experiences. The body parts are windows that showemotions and they would be particularly suitable to decodingaffective states. The group of extracted images is merged in oneimage with all the relevant information. The recovered image willserve as input to the classifiers. The analysis of images fromhuman body poses makes it possible to obtain relevantinformation through the combination of proper data in the sameimage. It is shown by experimental results that the SVM candetect emotion with good accuracy compared to other classifiers.
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| 23. |
- Ibrahim, Osama, et al.
(författare)
-
A Causal Mapping Simulation for Scenario Planning and Impact Assessment in Public Policy Problems - The Case of EU 2030 Climate and Energy Framework
- 2014
-
Ingår i: Proceedings of the 5th. World Congress on Social Simulation. - 9780692318959 ; , s. 284-296
-
Konferensbidrag (refereegranskat)abstract
- The ultimate objective of studying, modeling and analyzing policy problems is to incorporate the newest management technologies in the public policy decision-making in a meaningful and practically feasible way that adds significant value to the process. Simulation techniques can support the policy decision process by allowing empirical evaluation of the system dynamics present in the policy situation at hand. This paper presents a decision support simulation model for the European Union (EU) Climate and Energy targets 2030 as a case study of public policy decision making on the EU level. The simulation model is based on the problem structuring or framing by derivation of a system dynamics model from verbal descriptions of the problem, the graphical representation and analysis of change scenarios using the ‘Causal Mapping and Situation Formulation’ method. This approach supports the analysis of qualitative and quantitative information in order to facilitate both the conceptualization and formulation stages of the system modeling process. The resulting model, which is simply a topology of quantified causal dependencies among the problem key variables, can be used to simulate the transfer of change. The aim of simulation herein is to apply cognitive strategic thinking and scenario-based planning in a public policy problem situation in order to design alternative options and provide foresight or ex-ante impact assessment in terms of economic, social, environmental and other impacts.
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| 24. |
- Ibrahim, Osama, 1979-
(författare)
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A Systems Tool for Prescriptive Policy Analysis : Labelled Causal Mapping Method for Policy-oriented Modelling, Simulation and Decision analysis
- 2016
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The elicitation and processing of relevant information is the core of any policy decision-making process. Modelling is about making sense of the available information. Models are able to incorporate the contextual influences on policy making (e.g. political and economic environments, community sentiment…etc). Systems analysis allows quantitative, empirical testing of models that exist in the study of public policy. Simulation and visualisation techniques can help policy makers to reduce uncertainties on the possible impacts of policies.In an effort to enable adoption of the systems thinking approach to address the central problem of empirical political study, this thesis presents a framework for prescriptive policy analysis that provides decision support to: the problem definition, ex-ante impact assessment and evaluation activities carried out at the policy formulation stage of the policymaking process.We contribute a new tool for systemic modelling and simulation of public policy decision situations. It aims to facilitate the cognitive activity of representing complex mental models using system dynamics simulation modelling. Using the ’labelled causal mapping’ method, a policy-oriented problem structuring method introduced in this research, the tool bridges the gap between the user’s mental model and the explicit graphical representation in order to enable knowledge representation and system analysis. The method provides a basis for further computational decision analysis using a common policy appraisal format, a multi-criteria model with main evaluation criteria (effectiveness, efficiency, relevance, coherence and added value), linked to a set of measurable, context dependent attributes (targeted impact variables from the policy model).A web-based tool prototype has been implemented in a Node.js environment and is accessible both from a web-based graphical user interface as well as a hosted API. Multiple demonstration and test cases, from various policy areas and different EU policymaking levels, were used in several iterations of the build-evaluate cycle. This approach lead to the different studies that make up this research.
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| 25. |
- Ibrahim, Osama, et al.
(författare)
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An Integrated Decision Support System Framework for Strategic Planning in Higher Education Institutions
- 2014
-
Ingår i: Group Decision and Negotiation. A Process-Oriented View. - Heidelberg : Springer. - 9783319071787 - 9783319071794 ; , s. 237-245
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Konferensbidrag (refereegranskat)abstract
- Strategic planning models and information provision for decision-making in complex strategic situations are frequent subjects for scientific research. This research deals with the problem of supporting strategic planning decision-making in public higher education (HE) institutions by designing a Decision Support System (DSS) to be used by HE decision makers in implementing their strategic planning process, considering that the DSS would be anchored in on all databases of the institution’s information systems. This paper adopts a model for the strategic planning process, advocates the incorporation of technologies of participation (ToP) and introduces a collaborative framework for the planning activities at the different institutional levels to develop the institution’s strategic plan using a bottom-up approach. Based on the strategic planning process model, a DSS framework is proposed and decision support methods are suggested for the different modules of the DSS. The DSS provides intelligent support (on the individual, group and organizational levels) to strategic planning decisions in all stages of the process. By utilizing this DSS, it is possible to create better conditions for implementing the objectives of the future-oriented activity of the institution.
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| 26. |
- Ibrahim, Osama, 1979-
(författare)
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Design and Investigation of a Decision Support System for Public Policy Formulation
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The ultimate aim of support for public policy decision making is to develop ways of facilitating policymaking that can create policies that are consistent with the preferences of policymakers and stakeholders (such as an increase in economic growth, the reduction of social inequalities, and improvements to the environment), and that are at the same time based on the available knowledge and evidential information.Using the design science research methodology, an iterative design process was followed to build and evaluate a research artefact in the form of an analytical method that is also operationalised as a decision support system (DSS) – in order to facilitate the problem analysis, the impact assessment and the decision evaluation activities carried out at the policy formulation stage of the policymaking process. The DSS provides a web-based, user-friendly interface for two main software modules: (i) a tool for modelling and simulation of policy scenarios; and (ii) a tool for multi-criteria evaluation of policy decisions. The target end-users of the DSS tools are policymakers, the support staff of politicians, policy analysts and researchers within governmental departments and parliaments at the various institutional levels of the European Union.The proposed model-based decision support approach integrates systems thinking, problem structuring methods and multi-criteria decision analysis, in what can be described as a ‘sense-making’ approach. A new policy-oriented quantitative problem structuring method is introduced in this research, the ‘labelled causal mapping’ method, which aims to reduce the cognitive overload involved in representing complex mental models using system dynamics simulation modelling in order to facilitate knowledge representation and system analysis. One contribution of this work is an object-oriented implementation of a prototype tool for systems modelling and simulation of policy decision situations based on the labelled causal mapping method. The method provides a basis for further computational decision analysis. We proposed criteria models and data formats for common (generic) policy appraisal, and a preference elicitation method for in-depth decision evaluation based on the results of scenario simulation and the preferences of decision makers and stakeholder groups.The artefact evaluation clarifies how well the proposed approach and the DSS tool prototype support a solution to the problem and the extent to which the outcomes in two policy analysis use cases are useful in terms of output analysis and knowledge synthesis.The contributions of this research to theory and practice were articulated based on the design knowledge obtained through an iterative design process, notably the emergence of the concepts of transparency and intelligibility in policymodelling, (i.e., the need for explicit and interpretable models that can provide justification of a specific decision).
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| 27. |
- Kalinina, Maria, et al.
(författare)
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On the compatibility of uncertainty formalisms in multi-objective optimization
- 2014
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Ingår i: Frontiers in Artificial Intelligence and Applications. - Amsterdam : IOS Press. - 9781614994046 - 9781614994053 ; , s. 48-58
-
Konferensbidrag (refereegranskat)abstract
- Multi-objective optimization is a way to manage multiple objectives in analytical decision support systems. However, for real-life problems, different types of uncertainty often become prominent when defining the model. In this paper, we analyze these different types of uncertainties and suggest a suitable typology for a decision process based upon multi-objective optimization models. Uncertainty analysis can be performed based on the proposed typology; therefore, this analysis provides the necessary support for a decision maker in the identification the crucial uncertainty in the decision process. © 2014 The authors and IOS Press. All rights reserved.
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| 28. |
- Kalinina, Maria, et al.
(författare)
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Post Optimality Analysis of Pareto Optimal Set Through Weights Robustness
- 2014
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Ingår i: IEEE International Conference on Industrial Engineering and Engineering Management. - : IEEE Computer Society. ; , s. 34-38
-
Konferensbidrag (refereegranskat)abstract
- Traditional multi-objective optimization attempts to find Pareto optimal solutions. Since a Pareto optimal set can be huge, the problem of selecting one or few solutions occurs. Post optimality analysis in multi-objective optimization requires incorporation of decision makers' preferences in the form of weights. In this paper the concept of robustness with regards to weights is introduced. The different types of weights robustness show how sensitive a solution is to variation in weights' coefficients. An approach for analysis of Pareto optimal sets through weights robustness is then devised. The suggested approach can be of special interest in the presence of conflicting preferences among decision makers or when preference information is unavailable. In conclusion, managerial usage it in the different strategies for negotiation provides possibility to thoroughly weigh all alternatives before settling on an agreement.
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| 29. |
- Karlsson, Alexander, et al.
(författare)
-
Second-Order Credal Combination of Evidence
- 2013
-
Ingår i: Proceedings of the Eighth International Symposium on Imprecise Probability. - : Society for Imprecise Probability: Theories and Applications. - 9782913923355 ; , s. 169-178
-
Konferensbidrag (refereegranskat)abstract
- We utilize second-order probability distributions for modeling second-order information over imprecise evidence in the form of credal sets. We generalize the Dirichlet distribution to a shifted version, denoted the S-Dirichlet, which allows one to restrict the support of the distribution by lower bounds. Based on the S-Dirichlet distribution, we present a simple combination schema denoted as second-order credal combination (SOCC), which takes second-order probability into account. The combination schema is based on a set of particles, sampled from the operands, and a set of weights that are obtained through the S-Dirichlet distribution. We show by examples that the second-order probability distribution over the imprecise joint evidence can be remarkably concentrated and hence that the credal combination operator can significantly overestimate the imprecision.
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| 30. |
- Mccafferty, Kieran, et al.
(författare)
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HEROIC: a 5-year observational cohort study aimed at identifying novel factors that drive diabetic kidney disease: rationale and study protocol
- 2020
-
Ingår i: BMJ Open. - : BMJ. - 2044-6055 .- 2044-6055. ; 10:9, s. e033923-
-
Tidskriftsartikel (refereegranskat)abstract
- Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ. INTRODUCTION: Diabetic kidney disease (DKD) is the leading cause of end-stage kidney disease worldwide and a major cause of premature mortality in diabetes mellitus (DM). While improvements in care have reduced the incidence of kidney disease among those with DM, the increasing prevalence of DM means that the number of patients worldwide with DKD is increasing. Improved understanding of the biology of DKD and identification of novel therapeutic targets may lead to new treatments. A major challenge to progress has been the heterogeneity of the DKD phenotype and renal progression. To investigate the heterogeneity of DKD we have set up The East and North London Diabetes Cohort (HEROIC) Study, a secondary care-based, multiethnic observational study of patients with biopsy-proven DKD. Our primary objective is to identify histological features of DKD associated with kidney endpoints in a cohort of patients diagnosed with type 1 and type 2 DM, proteinuria and kidney impairment. METHODS AND ANALYSIS: HEROIC is a longitudinal observational study that aims to recruit 500 patients with DKD at high-risk of renal and cardiovascular events. Demographic, clinical and laboratory data will be collected and assessed annually for 5 years. Renal biopsy tissue will be collected and archived at recruitment. Blood and urine samples will be collected at baseline and during annual follow-up visits. Measured glomerular filtration rate (GFR), echocardiography, retinal optical coherence tomography angiography and kidney and cardiac MRI will be performed at baseline and twice more during follow-up. The study is 90% powered to detect an association between key histological and imaging parameters and a composite of death, renal replacement therapy or a 30% decline in estimated GFR. ETHICS AND DISSEMINATION: Ethical approval has been obtained from the Bloomsbury Research Ethics Committee (REC 18-LO-1921). Any patient identifiable data will be stored on a password-protected National Health Services N3 network with full audit trail. Anonymised imaging data will be stored in a ISO27001-certificated data warehouse.Results will be reported through peer-reviewed manuscripts and conferences and disseminated to participants, patients and the public using web-based and social media engagement tools as well as through public events.
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| 31. |
- Moran Cardenas, Antonio, et al.
(författare)
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Autonomous Motion of Mobile Robot Using Fuzzy-Neural Networks
- 2013
-
Ingår i: 2013 12th Mexican International Conference on Artificial Intelligence. - : IEEE. - 9781479926046 - 9781479926053 ; , s. 80-84
-
Konferensbidrag (refereegranskat)abstract
- This paper analyzes the performance and practical implementation of fuzzy-neural networks for the autonomous motion of mobile robots. The designed fuzzy-neural controller is a refined version of a conventional fuzzy controller, and was trained to optimize a given cost function minimizing positioning error. It was found that the mobile robot with fuzzy-neural controller presents good positioning and tracking performance for different types of desired trajectories. It was verified by computer simulation as well as experimentally using a laboratory-scale car-like robot model.
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| 32. |
- Moran Cardenas, Antonio, et al.
(författare)
-
Design of High Accuracy Tracking Systems with H Infinite Preview Control
- 2014
-
Ingår i: POLIBITS Research Journal on Computer Science and Computer Engineering With Applications. - 1870-9044. ; 50, s. 21-28
-
Tidskriftsartikel (refereegranskat)abstract
- Positioning and tracking control systems are an important component of autonomous robot applications. This paper presents the design method of tracking control systems based on H infinite preview control where the present and future desired positions of the robot are used to determine the control actions to be applied so that the robot describes the desired trajectory as close as possible. The performance improvements achieved with H infinite preview control have been examined in the frequency and time domains for different types of reference signals when applied to a one-dimensional positioning system. It was found that preview control improves the tracking performance by improving the phase response of the tracking system.
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| 33. |
- Natchimuthu, Sivakiruthika, et al.
(författare)
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Spatio-temporal variability of lake CH4 fluxes and its influence on annual whole lake emission estimates
- 2016
-
Ingår i: Limnology and Oceanography. - : Wiley. - 0024-3590 .- 1939-5590. ; 61
-
Tidskriftsartikel (refereegranskat)abstract
- Lakes are major sources of methane (CH4) to the atmosphere that contribute significantly to the global budget. Recent studies have shown that diffusive fluxes, ebullition and surface water CH4 concentrations can differ significantly within lakesspatially and temporally. CH4 fluxes may be affected at longer scales in response to seasons, temperature, lake mixing events, short term weather events like pressure variations, shifting winds and diel cycles. Frequent measurements of fluxes in the same system and integrated assessments of the impacts of the spatio-temporal variability are rare. Thereby, large scale assessments frequently lack information on this variability which can potentially lead to biased estimates. In this study, we analysed the variability of CH4 fluxes and surface water CH4 concentrations across open water areas of lakes in a small catchment in southwest Sweden over two annual cycles. Significant patterns in CH4 concentrations, diffusive fluxes, ebullition and total fluxes were observed in space (between and within lakes) and in time (over diel cycles to years). Differences observed among the lakes can be associated with lake characteristics. The spatial variability within lakes was linked to depth or distance to stream inlets. Temporal variability was observed at diel to seasonal scales and was influenced by weather events. The fluxes increased exponentially with temperature in all three lakes, with stronger temperature dependence with decreasing depth. By comparing subsets of our data with estimates using all data we show that considering the spatio-temporal variability in CH4 fluxes is critical when making whole lake or annual budgets.
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| 34. |
- Natchimuthu, Sivakiruthika, et al.
(författare)
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Spatiotemporal variability of lake pCO2 and CO2 fluxes in a hemiboreal catchment
- 2017
-
Ingår i: Journal of Geophysical Research: Biogeosciences. - : AMER GEOPHYSICAL UNION. - 2169-8953 .- 2169-8961. ; 122:1, s. 30-49
-
Tidskriftsartikel (refereegranskat)abstract
- ©2016. American Geophysical Union. All Rights Reserved.Globally, lakes are frequently supersaturated with carbon dioxide (CO2) and are major emitters of carbon to the atmosphere. Recent studies have generated awareness of the high variability in pCO2aq (the partial pressure corresponding to the concentration in water) and CO2 fluxes to the atmosphere and the need for better accounting for this variability. However, studies simultaneously accounting for both spatial and temporal variability of pCO2aq and CO2 fluxes in lakes are rare. We measured pCO2aq (by both manual sampling and mini loggers) and CO2 fluxes, covering spatial variability in open water areas of three lakes of different character in a Swedish catchment for 2 years. Spatial pCO2aq variability within lakes was linked to distance from shore, proximity to stream inlets, and deepwater upwelling events. Temporally, pCO2aq variability was linked with variability in dissolved organic carbon, total nitrogen, and dissolved oxygen. While previous studies over short time periods (1 to 6 h) observed gas transfer velocity (k) to be more variable than pCO2aq, our work shows that over longer time (days to weeks) pCO2aq variability was greater and affected CO2 fluxes much more than k. We demonstrate that ≥8 measurement days distributed over multiple seasons in combination with sufficient spatial coverage (≥8 locations during stratification periods and 5 or less in spring and autumn) are a key for representative yearly whole lake flux estimates. This study illustrates the importance of considering spatiotemporal variability in pCO2aq and CO2 fluxes to generate representative whole lake estimates.
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| 35. |
- Rázuri, Javier G., et al.
(författare)
-
Speech emotion recognition in emotional feedbackfor Human-Robot Interaction
- 2015
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Ingår i: International Journal of Advanced Research in Artificial Intelligence (IJARAI). - 2165-4050 .- 2165-4069. ; 4:2, s. 20-27
-
Tidskriftsartikel (refereegranskat)abstract
- For robots to plan their actions autonomously and interact with people, recognizing human emotions is crucial. For most humans nonverbal cues such as pitch, loudness, spectrum, speech rate are efficient carriers of emotions. The features of the sound of a spoken voice probably contains crucial information on the emotional state of the speaker, within this framework, a machine might use such properties of sound to recognize emotions. This work evaluated six different kinds of classifiers to predict six basic universal emotions from non-verbal features of human speech. The classification techniques used information from six audio files extracted from the eNTERFACE05 audio-visual emotion database. The information gain from a decision tree was also used in order to choose the most significant speech features, from a set of acoustic features commonly extracted in emotion analysis. The classifiers were evaluated with the proposed features and the features selected by the decision tree. With this feature selection could be observed that each one of compared classifiers increased the global accuracy and the recall. The best performance was obtained with Support Vector Machine and bayesNet.
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| 36. |
- Sundgren, David, 1967-
(författare)
-
Discrete Second-order Probability Distributions that Factor into Marginals
- 2011
-
Ingår i: Proceedings of the Seventh International Symposium on Imprecise Probabilities. - : SIPTA. - 9783902652409 ; , s. 335-342
-
Konferensbidrag (refereegranskat)abstract
- In realistic decision problems there is more often than not uncertainty in the background information. As for representation of uncertain or imprecise probability values, second-order probability, i.e. probability distributions over probabilities, offers an option. With a subjective view of probability second-order probability would seem to be impractical since it is hard for a person to construct a second-order distributions that reflects his or her beliefs. From the perspective of probability as relative frequency the task of constructing or updating a second-order probability distribution from data is somewhat easier. Here a very simple model for updating lower bounds of probabilities is employed. But the difficulties in choosing second-order distributions may be further alleviated if structural properties are considered. Either some of the probability values are dependent in some way, e.g. that they are known to be almost equal, or they are not dependent in any other way than what follows from that the values sum to one. In this work we present the unique family of discrete second-order probability distributions that correspond to the case where dependence is limited. These distributions are shown to have the property that the joint distributions are equal to normalised products of marginal distributions. The distribution family introduced here is a generalisation of a special case of the multivariate Pólya distribution and is shown to be conjugate prior to a compound hypergeometric distribution.
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| 37. |
- Sundgren, David
(författare)
-
Distribution of expected utility in second-order decision analysis
- 2007
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In decision analysis maximising the expected utility is an often used approach in choosing the optimal alternative. But when probabilities and utilities are vague or imprecise expected utility is fraught with complications. Studying second-order effects on decision analysis casts light on the importance of the structure of decision problems, pointing out some pitfalls in decision making and suggesting an easy to implement and easy to understand method of comparing decision alternatives. The topic of this thesis is such second-order effects of decision analysis, particularly with regards to expected utility and interval-bound probabilities. Explicit expressions for the second-order distributions inherent in interval-bound probabilities in general and likewise for distributions of expected utility for small decision problems are produced. By investigating these distributions the phenomenon of warping, that is concentration of belief, is studied.
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| 38. |
- Sundgren, David
(författare)
-
Distribution of expected utility in second-order decision analysis
- 2007
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In explicatione consiliorum, maxima facere communis utilitas saepe trita ratio deligendi meliorem optionem est. Verum si probabilitates et utilitates incertae vel dubiae sint, communis utilitas perturbationes affert. Studium secundi ordinis effectuum in explicatione consiliorum explanat momentum structurae quaestionium consilii, insidias aliquas ad consilium capiendum indicat et facilem ad efficiendum et intellegendum rationem comparandi varia consilia suadet. Haec thesis tractat de secundi ordinis effectibus explicationis consilii, praesertim de commune utilitate et de probabilitatibus coniunctis intervallo. Voces apertae distributionum ordinis secundi in probabilitatibus intervallo conjunctis insitarum omnino et item distributionum utilitatis expectatae in parvis quaestionibus consiliorum eduntur. His distributionibus cognitis studetur res inflexionis, aliter dictu intentio fidei.
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| 39. |
- Sundgren, David, 1967-
(författare)
-
Expected Utility from Multinomial Second-order Probability Distributions
- 2010
-
Ingår i: "Polibits" Research Journal on Computer Science and Computer Engineering with Applications. - Mexico City : Center for Technological Design and Development in Computer Science (CIDETEC). - 1870-9044. ; :42, s. 71-75
-
Tidskriftsartikel (refereegranskat)abstract
- We consider the problem of maximizing expected utility when utilities and probabilities are given by discrete probability distributions so that expected utility is a discrete stochastic variable. As for discrete second-order distributions, that is probability distributions where the variables are themselves probabilities, the multinomial family is a reasonable choice at least if first-order probabilities are interpreted as relative frequencies. We suggest a decision rule theat reflects the uncertainty present in distribution-based probabilities and utilities and we show an example of this rule in action with multinomial second-order distributions.
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| 40. |
- Sundgren, David, et al.
(författare)
-
On Dependence in Second-Order Probability
- 2012
-
Ingår i: Scalable Uncertainty Management. - Berlin, Heidelberg : Springer Berlin/Heidelberg. - 9783642333613 - 9783642333620 ; , s. 379-391
-
Konferensbidrag (refereegranskat)abstract
- We present a notion, relative independence, that models independence in relation to a predicate. The intuition is to capture the notion of a minimum of dependencies among variables with respect to the predicate. We prove that relative independence coincides with conditional independence only in a trivial case. For use in second-order probability, we let the predicate express first-order probability, i.e. that the probability variables must sum to one in order to restrict dependency to the necessary relation between probabilities of exhaustive and mutually exclusive events. We then show examples of Dirichlet distributions that do and do not have the property of relative independence. These distributions are compared with respect to the impact of further dependencies, apart from those imposed by the predicate.
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| 41. |
- Sundgren, David, 1967-, et al.
(författare)
-
On Dependence in Second-Order Probability
- 2012
-
Ingår i: Scalable Uncertainty Management. - Berlin/Heidelberg : Springer Berlin/Heidelberg. - 9783642333613 ; , s. 379-391
-
Konferensbidrag (refereegranskat)abstract
- We present a notion, relative independence, that models independence in relation to a predicate. The intuition is to capture the notion of a minimum of dependencies among variables with respect to the predicate. We prove that relative independence coincides with conditional independence only in a trivial case. For use in second-order probability, we let the predicate express first-order probability, i.e. that the probability variables must sum to one in order to restrict dependency to the necessary relation between probabilities of exhaustive and mutually exclusive events. We then show examples of Dirichlet distributions that do and do not have the property of relative independence. These distributions are compared with respect to the impact of further dependencies, apart from those imposed by the predicate.
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| 42. |
- Sundgren, David
(författare)
-
Public Procurement of Complex IT Systems Within the Electricity Sector -Does the Law Encourage Good Business Practice?
- 2003
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The subject of this thesis is the Swedish Act (1992:1528) onPublic Procurement (APP) and its application in procurementwithin the electricity sector of certain complex IT systems.During the course of such procurements a need for flexibilityregarding the system functionality and the contractual scope ingeneral frequently arises. This is often due to the sheercomplexity of the system and the milieu that surrounds it.The Act on Public Procurement, which often applies inprocurement within the electric-ity sector, is based on thenotion that the customer may only acquire an object that issimilar to that initially described in contract notices andcontract documents. Between this basic notion and the need forflexibility in procurement of the IT-systems there is a clearconflict. This thesis is aimed at exploring this conflict.The APP is designed for procurement of a great variety ofobjects and different rules apply depending on the situation.Which provisions to apply are decided by the kind of customerand its kind of business activity, the estimated contractvalue, and the classifi-cation of the public contract as asupply, works, or service contract.Procurement of certain complex IT systems has someproperties that require particular attention and theseproperties do not seem to have been sufficiently observed whenthe APP was written. The law appears to assume that a clearspecification is readily avail-able in the early stages of aprocurement process and that well-functioning competition isprevalent. Complex IT systems may for several reasons rarely beultimately specified at the outset and therefore they ought notto be treated as if that were the case.The research work has consisted in studying what room forflexibility concerning system functionality and contractconditions the law permits during the course of theprocure-ment; during the evaluation of tenders, duringnegotiations, at the signing of the con-tract, and when changesin the contract or further contracts related to the firstcontract become necessary.To study the need for flexibility and how the contractparties manage this need in prac-tice, two case studies havebeen carried out within the research work. The result of thesecase studies has been related to the theoretical discussions onthe permissible level of flexibility. In one of the cases therules on public procurement may have cased some problems as aneed for substantial changes arose. In the other case there wasno need for major changes and consequently the rules did notcause any concern in this respect.Key words:Public Procurement, IT Systems, ElectricitySector, Good Business Practice
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| 43. |
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| 44. |
- Sundgren, David, 1967-, et al.
(författare)
-
Shifted Dirichlet Distributions as Second-Order Probability Distributions that Factors into Marginals
- 2009
-
Ingår i: Proceedings of the Sixth International Symposiumon Imprecise Probability. - : SIPTA. ; , s. 405-410, s. 405-+, s. 405-410
-
Konferensbidrag (refereegranskat)abstract
- In classic decision theory it is assumed that a decisionmaker can assign precise numerical values corresponding to the true value of each consequence, as well as precise numerical probabilities for their occurrences. In attempting to address real-life problems, where uncertainty in the input data prevails, some kind of representation of imprecise information is important. Second-order distributions, probability distributions over probabilities, is one way to achieve such a representation. However, it is hard to intuitively understand statements in a multi-dimensional space and user statements must be provided more locally. But the information-theoretic interplay between joint and marginal distributions may give rise to unwanted effects on the global level. We consider this problem in a setting of second-order probability distributions and find a family of distributions that normalised over the probability simplex equals its own product of marginals. For such distributions, there is no flow of information between the joint distributions and the marginal distributions other than the trivial fact that the variables belong to the probability simplex.
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| 45. |
- Sundgren, David, et al.
(författare)
-
Some Properties of Aggregated Distributions over Expected Values
- 2008
-
Ingår i: MICAI 2008: Advances in Artificial Intelligence. - Berlin, Heidelberg : Springer Berlin/Heidelberg. - 9783540886358 - 9783540886365 ; , s. 699-709
-
Konferensbidrag (refereegranskat)abstract
- Software agents and humans alike face severe difficulties in making decisions in uncertain contexts. One approach is to formalise the decision situation by means of decision theory, i.e. probabilities and utilities leading to the principle of maximising the expected utility. Expected utility is here considered as a stochastic variable; under the assumption that all utility values are equally likely, and that each vector of probability values is equally likely, the probability distribution of expected utility is calculated for two, three, and four possible outcomes. The effect of these probability distributions concentrating around the middle value is explored and its significance for making decisions.
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| 46. |
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| 47. |
- Sundgren, David, et al.
(författare)
-
Some Second Order Effects on Interval Based Probabilities
- 2006
-
Ingår i: Proceedings of the Nineteenth International Florida Artificial Intelligence Research Society Conference. - Menlo Park, California : AAAI Press. - 9781577352617 ; , s. 848-853
-
Konferensbidrag (refereegranskat)abstract
- In real-life decision analysis, the probabilities and values of consequences are in general vague and imprecise. One way to model imprecise probabilities is to represent a probability with the interval between the lowest possible and the highest possible probability, respectively. However, there are disadvantages with this approach, one being that when an event has several possible outcomes, the distributions of belief in the different probabilities are heavily concentrated to their centers of mass, meaning that much of the information of the original intervals are lost. Representing an imprecise probability with the distribution’s center of mass therefore in practice gives much the same result as using an interval, but a single number instead of an interval is computationally easier and avoids problems such as overlapping intervals. Using this, we demonstrate why second-order calculations can add information when handling imprecise representations, as is the case of decision trees or probabilistic networks. We suggest a measure of belief density for such intervals. We also demonstrate important properties when operating on general distributions. The results herein apply also to approaches which do not explicitly deal with second-order distributions, instead using only first-order concepts such as upper and lower bounds.
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| 48. |
- Sundgren, David, et al.
(författare)
-
Structure information in decision trees and similar formalisms
- 2007
-
Ingår i: Proceedings of the Twentieth International Florida Artificial Intelligence Research Society Conference, FLAIRS 2007. - Menlo Park, California : AAAI Press. - 9781577353195 ; , s. 62-67
-
Konferensbidrag (refereegranskat)abstract
- In attempting to address real-life decision problems, where uncertainty about input data prevails, some kind of representation of imprecise information is important and several have been proposed over the years. In particular, first-order representations of imprecision, such as sets of probability measures, upper and lower probabilities, and interval probabilities and utilities of various kinds, have been suggested for enabling a better representation of the input sentences. A common problem is, however, that pure interval analyses in many cases cannot discriminate sufficiently between the various strategies under consideration, which, needless to say, is a substantial problem in real-life decision making in agents as well as decision support tools. This is one reason prohibiting a more wide-spread use. In this article we demonstrate that in many situations, the discrimination can be made much clearer by using information inherent in the decision structure. It is discussed using second-order probabilities which, even when they are implicit, add information when handling aggregations of imprecise representations, as is the case in decision trees and probabilistic networks. The important conclusion is that since structure carries information, the structure of the decision problem influences evaluations of all interval representations and is quantifiable.
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| 49. |
- Sundgren, David, 1967-
(författare)
-
The Apparent Arbitrariness of Second-Order Probability Distributions
- 2011
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Adequate representation of imprecise probabilities is a crucial and non-trivial problem in decision analysis. Second-order probability distributions is the model for imprecise probabilities whose merits are discussed in this thesis. That imprecise probabilities may be represented by second-order probability distributions is well known but there has been little attention to specific distributions. Since different probability distributions have different properties, the study of the desired properties of models of imprecise probabilities with respect to second-order models require analysis of particular second-order distributions. An often held objection to second-order probabilities is the apparent arbitrariness in the choice of distribution. We find some evidence that the structure of second-order distributions is an important factor that prohibits arbitrary choice of distributions. In particular, the properties of two second-order distributions are investigated; the uniform joint distribution and a variant of the Dirichlet distribution that has the property of being the normalised product of its own marginal distributions. The joint uniform distribution is in this thesis shown to have marginal distributions that belie the supposed non-informativeness of a uniform distribution. On the other hand, the modified Dirichlet distribution discovered here has its information content evenly divided among the joint and marginal distributions in that the total correlation of the variables is minimal. It is also argued in the thesis that discrete distributions, as opposed to the continuous distributions mentioned above, would have the advantage of providing a natural setting for updating of lower bounds, and computation of expected utility is made more efficient.
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| 50. |
- Sundgren, David, et al.
(författare)
-
Uncertainty Levels of Second-Order Probability
- 2013
-
Ingår i: POLIBITS Research Journal on Computer Science and Computer Engineering With Applications. - : Instituto Politécnico Nacional. - 1870-9044. ; :48, s. 5-11
-
Tidskriftsartikel (refereegranskat)abstract
- Since second-order probability distributions assign probabilities to probabilities there is uncertainty on two levels. Although different types of uncertainty have been distinguished before and corresponding measures suggested, the distinction made here between first- and second-order levels of uncertainty has not been considered before. In this paper previously existing measures are considered from the perspective of first- and second-order uncertainty and new measures are introduced. We conclude that the concepts of uncertainty and informativeness needs to be qualified if used in a second-order probability context and suggest that from a certain point of view information can not be minimized, just shifted from one level to another.
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