| 1. |
- Lindquist, Malin, 1975-
(author)
-
Electronic tongue for water quality assessment
- 2007
-
Doctoral thesis (other academic/artistic)abstract
- This thesis describes the work on the development of a new electronic tongue for water quality assessment. The aim of this work is to build a complete system including a sensor and associated data analysis methods which is able to detect quality changes in drinking water and warn the user if the water is not suitable for drinking. Therefore, the main design issues were to build a portable, robust electronic tongue which provides a fast estimate of the water quality rather than identify the type of the contamination. In this sense, the system has a simple interface resembling traffic light signals. The system responds with green light for good water quality, red for bad quality and yellow if the result is uncertain. The electronic tongue sensor is based on voltammetry, which gives a relatively simple and robust system. It is suitable for the considered applications, since it is able to measure small changes in the chemical and micro-organic content in water. These properties are very important for our goal to develop an electronic tongue for water quality assessment. During the development process, the sensor system was modified in order to improve the system’s mobility and robustness. Moreover, the long-term stability and the extent of the sensor drift were evaluated for continuous use. The response time for the sensor is relatively short, but it generates large amounts of data. Therefore, there is a need for pre-processing and feature extraction methods to deal with the complexity of data. This is done with the help of multivariate analysis method. The quality assessment is done with different classification algorithms. We implemented fuzzy clustering and self-organizing maps. In this thesis, two real applications are also considered, where the measurement is taking place in streaming water. In the first case, the electronic tongue could be placed directly at a water tap where random measurements occur. In the second application continuous measurements are performed and information about the sensor drift is used in the data analysis. The evaluation confirmed that the improved sensor system fulfills the requirements for on-line measurements of water quality.
|
|
| 2. |
- Svenmarck, Peter
(author)
-
Human Engineering of Sensor Fusion Systems in Fighter Aircraft
- 2001
-
Doctoral thesis (other academic/artistic)abstract
- A pressing concern in modern fighter aircraft cockpit design is how to present and reduce large amounts of data obtained from several sensor observations of the same object. Currently, sensor observations are presented individually as overlays or in different displays requiring the pilot to control each sensor and integrate observations. The increased number of sensors and communication networks covering extensive ranges has, however, led to a situation that hampers pilots' situation awareness and decision-making. One approach to support the pilot is automatic information management. Although considerable technological research has been conducted on automatic sensor fusion and process refinement, little is known about how to integrate systems capabilities with pilots' decision-making.This thesis focuses on the factors involved in pilots' control of sensor fusion systems for tracking, classifying,and identifying objects, which are presented on the indicators in the cockpit of fighter aircraft. A cognitive systems engineering perspective was applied, since sensor fusion systems by definition automate parts of the information management. The emphasis in cognitive systems engineering is to create a complementary role for technological solutions and operator competence. A comparison of two major programs on decision support systems shows that striking the right balance between available technology and pilot expertise is important for the development of useful systems.Since little research has directly addressed pilots' control of sensor fusion systems, a conceptual model is presented based on systems characteristics and a review of factors likely to be important. The model shows how pilots' mission goals specify a desired situation awareness that determines the control of sensors. Pilots' control sensor fusion systems by designating important objects and areas, and intervening on exceptions of an essentially autonomous system. The systems support pilots' situation awareness with visualization of information and by improving their evaluation of the situation. Remaining uncertainties that delay action are reduced with suitable strategies. A High Range Resolution (HRR) radar identification system was simulated and evaluated for further understanding of the uncertainty in target identity that is important for pilots. The interface for the HRR system shows how supervisory control of system performance, levels of control, and visualization of conflicts are general factors that may be important for control of sensor fusion systems.The thesis shows that an appropriate function allocation for automatic sensor management may have to consider pilots' individual differences in minimizing goal trees and characterizing situations. Such factors may be important for pilots' expectations on sensor management that makes them use and trust system inferences appropriately. Interviews with pilots can provide some understanding of the factors involved in sensor control. However, since many of the judgments and tactical patterns involved in pilots' decision making are overlearned for efficient automatic performance, they may not be able to explain their behavior in detail. The thesis shows that analyzing pilot performance using neurofuzzy models may be a useful way to describe how situations drive responses. The linguistic form of fuzzy rules gives an intuitive understanding of the relationship in a presentational form that can be integrated with sensor management control rules.
|
|
