This study presents a case-based reasoning (CBR) system that makes use of general domain knowledge -referred to as a knowledgeintensive CBR system. The system applies a Bayesian analysis aimed at increasing the accuracy of the similarity assessment. The idea is to employ the Bayesian posterior distribution for each case symptom to modify the case descriptions and the dependencies in the model. To evaluate the system, referred to as BNCreek, two experiment sets are set up from a "food" and an "oil well drilling" application domain. In both of the experiments, the BNCreek is evaluated against two corresponding systems named TrollCreek and myCBR with Normalized Discounted Cumulative Gain (NDCG) and interpolated average Precision-Recall as the evaluation measures. The obtained results reveal the capability of Bayesian analysis to increase the accuracy of the similarity assessment.

This paper presents fault diagnosis and problem solving under uncertainty by a Bayesian supported knowledge-intensive case-based reasoning (CBR) system called BNCreek. In this system, the main goal is to diagnose the causal failures behind the symptoms in complex and uncertain domains. The system’s architecture is described in three aspects: the general, structural, and functional architectures. The domain knowledge is represented by formally defined methods. An integration of semantic networks, Bayesian networks, and CBR is employed to deal with the domain uncertainty. An experiment is conducted from the oil well drilling domain, which is a complex and uncertain area as an application domain. The system is evaluated against the expert estimations to find the most efficient solutions for the problems. The obtained results reveal the capability of the system in diagnosing causal failures.

Wethers and ewes were used to study the effect of catheter or repeated venipuncture on circulating cortisol and leukocyte concentrations and physical behaviors following administration of lipopolysaccharide (LPS), a gram-negative bacteria cell wall component. Animals were injected with LPS or saline, as a control, to induce an innate immune system response. In addition, blood leukocytes and cortisol levels were studied to determine the effect of sex on immunological and stress responses. Thirty-eight mature Dorset and Suffolk wethers and ewes were assigned into one of four treatment groups: 1.) no-catheter + LPS treated ewes (n=5) and wethers (n=4) that were restrainted to draw blood from the jugular vein; 2.) no-catheter + saline treated ewes (n=6) and wethers (n=4) restrained to draw blood from the jugular vein; 3.) catheter + LPS consisting of LPS-treated ewes (n=6) and wethers (n=4) in which a jugular catheter was placed to draw blood; and 4.) catheter + saline treated ewes (n=6) and wethers (n=4) with a jugular catheter. Blood was collected from the jugular vein catheter, which was placed into the jugular vein the day before the experiment and anchored with a stitch to secure it or venipuncture before the challenge followed by post challenge samples every 30 min for 3 h and every hour until 12 h, and once at 24 h. Physical behaviors and rectal temperatures were monitored before LPS administration and every hour for 12 h post challenge. Total white blood cell counts and leukocyte differentials including lymphocytes, monocytes, and granulocytes were measured immediately after collection using a veterinary hematology blood analyzer (Abaxis VetScan HM5, Abaxis Inc.), and remaining samples were centrifuged, and plasma was collected and stored at-20°C until concentration of cortisol was determined by ELISA. Treatment with LPS resulted in increased cortisol concentrations, rectal temperatures, lethargy, and nasal discharge, as well as decreased WBC count and appetite in ewes and wethers. Catheter insertion alone resulted in increased WBC count, but did not affect cortisol. However, a significant increased in cortisol occurred in LPS treated sheep fitted with catheters compared to those without. Rectal temperatures during LPS challenge were greater in wethers than ewes, and a greater decrease in total WBC count and leukocyte differentials was seen in ewes when compared to wethers. Moreover, there was no significant effect of sex on cortisol concentrations. In summary, there were no differences in cortisol concentrations between sexes and no significant effect of the catheter alone. However, during the LPS challenge catheter exacerbated the innate immune response and cortisol levels, and rectal temperature and WBC count were affected by sex. Therefore, catheter placement created an additional stressor that augmented the LPS-induced immune response. iii Dedication This thesis is dedicated to the memory of my mother, Malakeh, for making me be who I am, and to my strong father, Akbar, for supporting me all the way, and ...

This paper presents the inference and reasoning methods in a Bayesian supported knowledge-intensive case-based reasoning (CBR) system called BNCreek. The inference and reasoning process in this system is a combination of three methods. The semantic network inference methods and the CBR method are employed to handle the difficulties of inferencing and reasoning in uncertain domains. The Bayesian network inference methods are employed to make the process more accurate. An experiment from oil well drilling as a complex and uncertain application domain is conducted. The system is evaluated against expert estimations and compared with seven other corresponding systems. The normalized discounted cumulative gain (NDCG) as a rank-based metric, the weighted error (WE), and root-square error (RSE) as the statistical metrics are employed to evaluate different aspects of the system capabilities. The results show the efficiency of the developed inference and reasoning methods.