Explanation-based learning: its role in problem solving

Abstract

‘Explanation-based’ learning is a semantically-driven. knowledge-intensive paradigm for machine learning which contrasts sharply with syntactic or ‘similarity-based’ approaches. This paper redevelops the foundations of EBL from the perspective of problem-solving. Viewed in this light, the technique is revealed as a simple modification to an inference engine which gives it the ability to generalize the conditions under which the solution to a particular problem holds. We show how to embed generalization invisibly within the problem solver, so that it is accomplished as inference proceeds rather than as a separate step. The approach is also extended to the more complex domain of planning to illustrate that it is applicable to a variety of logic-based problem-solvers and is by no means restricted to only simple ones. We argue against the current trend to isolate learning from other activity and study it separately, preferred instead to integrate it into the very heart of problem solving.     

Early and Sustained Enrichment of Serum n-3 Long Chain Polyunsaturated Fatty Acids in Dogs Fed a Flaxseed Supplemented Diet

A study was conducted in dogs to assess n-3 long chain polyunsaturated fatty acid incorporation after feeding an α-linolenic (ALA)-rich flaxseed supplemented diet (FLX) for 84 days. Serum total phospholipids (PL), triacylglycerol (TG), and cholesteryl esters (CE) were isolated at selected times and fatty acid methyl esters were analyzed. Increased LA was seen in the FLX-PL fraction after 28 days and an expected decrease in PL–AA. Enrichment of ALA, eicosapentaenoic acid (EPA) and docosapentaenoic acid n-3 (DPAn-3) in the FLX-group occurred early on (day 4) in both PL and TG fractions but no docosahexaenoic acid (DHA) was found, consistent with data from other species including humans. In contrast, no accumulation of DPAn-3 was seen in serum-CE, suggesting that this fatty acid does not participate in reverse-cholesterol transport. The accumulation of DPAn-3 in fasting PL and TG fractions is likely due to post-absorptive secretion after tissue synthesis. Because conversion of DPAn-3 to DHA occurs in canine neurologic tissues, this DPAn-3 may provide a circulating reservoir for DHA synthesis in such tissues. The absence of DPAn-3 in serum-CE suggests that such transport may be unidirectional. Although conversion of DPAn-3 to DHA is slow in most species, one-way transport of DPAn-3 in the circulation may help conserve this fatty acid as a substrate for DHA synthesis in brain and retinal tissues especially when dietary intakes of DHA are low.     

Qualitative visualization and quantitative analysis of milk flow using electrical resistance tomography

Product quality enhancement, reduction in waste and energy consumption and cost minimization are the results of having good automatic process control in all processes including the milk powder production process. Having an accurate, multi-dimensional and continuous knowledge of the process which is the fundamental requirement of automatic process control can be provided by the application of process tomography. Electrical Resistance Tomography (ERT), a novel, simple, and robust method of process imaging when conducted on two adjacent planes on a pipeline, provides the ability to extract multi-dimensional qualitative and quantitative flow information. The application of an ERT system to flow monitoring and control in the dairy industry has not been researched comprehensively before. Yet it is extremely desirable and beneficial to be able to remotely inspect the internal volume of pipes without invading the process, which is the aim of this research.     

Controllability of Heat Exchanger Networks

A heat exchanger network (HEN) is the heart of a heat-integrated plant, and classical synthesis methologies assume all design operating conditions are constant values and overlook controllability issues. The controllability measures presented in this paper are intended to assess the controllability of a HEN through a simple and comprehensive methodology consisting of five steps that allows an easy screening process to determine a more controllable HEN.     

Airborne lidar bathymetry: assessing quality assurance and quality control methods with Leica Chiroptera examples

Airborne lidar bathymetry (ALB) is an effective advanced technology for mapping and measuring water depth in shallow water coastal zones as well as inland freshwater bodies such as rivers and lakes. The ability of light beams to detect and traverse shallow water columns has provided valuable information about unmapped and often poorly understood coastal and inland waterbodies. ALB surveys require specific best practices and quality management procedures to provide the highest-quality end product. Implementing quality assurance procedures before the survey commences and frequent quality control checks during and after the survey are essential steps. In this article, we summarize overall ALB development history, discuss specific ALB requirements, and provide examples that reflect our experiences of the Leica Chiroptera ALB system. Supplemental surveys, in situ measurements, and developing in-house algorithms are all beneficial and have the means to increase confidence and versatility of lidar bathymetry.     

Milk total solids and fat content soft sensing via electrical resistance tomography and temperature measurement

The novel, robust and high speed method of process imaging, electrical resistance tomography (ERT), can potentially provide the user with the multidimensional information required for automatic process monitoring and control. In this study it has been applied for the first time in the non-invasive analysis of various milk solutions for quantitative auditing and attaining informative data, such as total solids and fat content at constant temperature in the various stages of milk processing. Although various other methods of total solids and fat content measurement are being applied, most have disadvantages such as imprecision and sampling problems. No other existing methods have the capability of providing dynamic, spatially distributed knowledge of the data variation while also enabling visual access into opaque solutions and vessels.The proposed method provides an average accuracy of over 96% in milk total solids and fat content measurement. Such accuracy is comparable to the precision of current methods of off-line point measurements, with the advantage of providing continuous output data which is crucial for process control applications.     

The Effect of Adhesive Thickness on Joint Strength

The hypothesis that the weakness of thick joints is due to stresses caused by contraction of the adhesive on setting requires a linear relation between the strength of a joint and the adhesive thickness. However it is statistically preferable to describe our experimental data by relating either log strength or linear strength to log thickness. The predicted slopes or thickness-dependences of the joint strengths are at least three orders greater than those observed. Both the preferred relations have a possible theoretical basis, namely the statistical nature of rupture.     

Predicate Encryption Supporting Disjunctions, Polynomial Equations, and Inner Products

Predicate encryption is a new paradigm for public-key encryption that generalizes identity-based encryption and more. In predicate encryption, secret keys correspond to predicates and ciphertexts are associated with attributes; the secret key SK _f corresponding to a predicate f can be used to decrypt a ciphertext associated with attribute I if and only if f(I)=1. Constructions of such schemes are currently known only for certain classes of predicates. We construct a scheme for predicates corresponding to the evaluation of inner products over ? _N (for some large integer N). This, in turn, enables constructions in which predicates correspond to the evaluation of disjunctions, polynomials, CNF/DNF formulas, thresholds, and more. Besides serving as a significant step forward in the theory of predicate encryption, our results lead to a number of applications that are interesting in their own right.