Logical form generation as abduction: Part I. Representation of linguistic concepts

For some time, researchers have become increasingly aware that some aspects of natural language processing can be viewed as abductive inference. This article describes knowledge representation in dual-route parsimonious covering theory, based on an existing diagnostic abductive inference model, extended to address issues specific to logic form generation. the two routes of covering deal with syntactic and semantic aspects of language, and are integrated by attributing both syntactic and semantic facets to each “open class” concept. Such extensions reflect some fundamental differences between the two task domains. the syntactic aspect of covering is described to show the differences, and some interesting properties are established. the semantic associations are characterized in terms of how they can be used in an abductive model. A major significance of this work is that it paves the way for a nondeductive inference method for word sense disambiguation and logical form generation, exploiting the associative linguistic knowledge. This approach sharply contrasts with others, where knowledge has usually been laboriously encoded into pattern-action rules that are hard to modify. Further, this work represents yet another application for the general principle of parsimonious covering. © 1994 John Wiley & Sons, Inc.     

A column generation approach for the maximal covering location problem

This article presents a column generation algorithm to calculate new improved lower bounds to the solution of maximal covering location problems formulated as a p‐median problem. This reformulation leads to instances that are difficult for column generation methods. The traditional column generation method is compared with the new approach, where the reduced cost criterion used at the column selection is modified by a Lagrangean/surrogate multiplier. The efficiency of the new approach is tested with real data, where computational tests were conducted and showed the impact of sparsity and degeneracy on column generation‐based methods.     

Synthetic on-line signature generation. Part II: Experimental validation

A novel method for the generation of synthetic on-line signatures based on the spectral analysis and the Kinematic Theory of rapid human movements, was presented in Part I of this series of two papers. In the present paper, the experimental framework used for the validation of the novel approach is described. The validation protocol, which uses different development and test sets in order to achieve unbiased results, includes the comparison of real and synthetic databases in terms of (i) visual appearance, (ii) statistical information, and (iii) performance evaluation of three competitive and totally different verification systems. The experimental results show the high similarity existing between synthetically generated and humanly produced samples, and the great potential of the method for the study of the signature trait.     

A novel approach of three-dimensional hybrid grid methodology: Part 1. Grid generation

We propose a novel approach of three-dimensional hybrid grid methodology, the DRAGON grid method in the three-dimensional space. The DRAGON grid is created by means of a Direct Replacement of Arbitrary Grid Overlapping by Nonstructured grid, and is structured-grid dominated with unstructured grids in small regions. The DRAGON grid scheme is an adaptation to the Chimera thinking. It is capable of preserving the advantageous features of both the structured and unstructured grids, and eliminates/minimizes their shortcomings. In the present paper, we describe essential and programming aspects, and challenges of the three-dimensional DRAGON grid method, with respect to grid generation. We demonstrate the capability of generating computational grids for multi-components complex configurations.     

Logical structure analysis and generation for structured documents: a syntactic approach

This paper presents a syntactic method for sophisticated logical structure analysis that transforms document images with multiple pages and hierarchical structure into an electronic document based on SGML/XML. To produce a logical structure more accurately and quickly than previous works of which the basic units are text lines, the proposed parsing method takes text regions with hierarchical structure as input. Furthermore, we define a document model that is able to describe geometric characteristics and logical structure information of documents efficiently and present its automated creation method. Experimental results with 372 images scanned from the IEEE Transactions on Pattern Analysis and Machine Intelligence (TPAMI) show that the method has performed logical structure analysis successfully and generated a document model automatically. Particularly, the method generates SGML/XML documents as the result of structural analysis, so that it enhances the reusability of documents and independence of platform.     

Logical data base design: A management-oriented approach

A logical data base consists of data definitions and data relationships. It is typically very large and complex even for a small organization, but it is generally designed in an ad hoc manner. However, several approaches have recently been proposed that allow for a systematic logical data base design.To make a data base more useful to the managers, it is imperative to encourage and obtain their involvement in the initial phase of the logical data base design. “Surface semantic models” are used in the logical data base design process to increase this involvement. A special type of this, called a “hierarchical external view model”, is proposed. It has been successfully used to develop a logical data base for the Department of Aging in Pennsylvania.     

A new multi-gene genetic programming approach to non-linear system modeling. Part II: geotechnical and earthquake engineering problems

Complexity of analysis of geotechnical behavior is due to multivariable dependencies of soil and rock responses. In order to cope with this complex behavior, traditional forms of engineering design solutions are reasonably simplified. Incorporating simplifying assumptions into the development of the traditional methods may lead to very large errors. This paper presents an endeavor to exploit a robust multi-gene genetic programming (MGGP) method for the analysis of geotechnical and earthquake engineering systems. MGGP is a modified genetic programming approach for model structure selection combined with a classical technique for parameter estimation. To justify the abilities of MGGP, it is systematically employed to formulate the complex geotechnical engineering problems. Different classes of the problems analyzed include the assessment of (i) undrained lateral load capacity of piles, (ii) undrained side resistance alpha factor for drilled shafts, (iii) settlement around tunnels, and (iv) soil liquefaction. The validity of the derived models is tested for a part of test results beyond the training data domain. Numerical examples show the superb accuracy, efficiency, and great potential of MGGP. Contrary to artificial neural networks and many other soft computing tools, MGGP provides constitutive prediction equations. The MGG-based solutions are particularly valuable for pre-design practices.     

Meta-firewall: A sixth generation firewall — Part 1

Terminology in the firewall area is still confusing. Proxies, packet filters, ‘stateful’ filters, hybrid approaches, fifth generation firewalls and many more rule the market, and thus rule the user's mind of what is good and what is bad. But few people (1) have thought about the relationships between all those technologies, how they can interact, and how they can be integrated to increase security on a perimeter network to a maximum. Let us call this approach a ‘meta-firewall’, designed to provide maximum security for dedicated purposes. All of the issues involved in planning for a solution for any network cannot be discussed, but it is an approach to a new way of thinking what can be done with firewalls and the like. The first part of this two-part article begins to build the layers of security in a firewall for an imaginary company.     

Meta-firewall: A sixth generation firewall — Part 2

Terminology in the firewall area is still confusing. Proxies, packet filters, ‘stateful’ filters, hybrid approaches, fifth generation firewalls and many more rule the market, and thus rule the user's mind of what is good and what is bad. But few people have thought about the relationships between all those technologies, how they can interact, and how they can be integrated to increase security on a perimeter network to a maximum. Let us call this approach a ‘meta-firewall’, designed to provide maximum security for dedicated purposes. All of the issues involved in planning for a solution for any network cannot be discussed, but it is an approach to a new way of thinking what can be done with firewalls and the like. This concluding part of a two-part article continues to build the layers of security to make a ‘meta-firewall’.     

Local stability of trusses in the context of topology optimization Part II: A numerical approach

The paper considers the problem of optimal truss topology design with respect to stress, slenderness, and local buckling constraints. An exact problem formulation is used dealing with the inherent difficulty that the local buckling constraints are discontinuous functions in the bar areas due to the topology aspect. This exact problem formulation has been derived in Part I. In this paper, a numerical approach to this nonconvex and largescale problem is proposed. First, discontinuity of constraints is erased by providing an equivalent formulation in standard form of nonlinear programming. Then a linearization concept is proposed partly preserving the given problem structure. It is proved that the resulting sequential linear programming algorithm is a descent method generating truss designs feasible for the original problem. A numerical test on a nontrivial example shows that the exact treatment of the problem leads to different designs than the usual local buckling constraints neglecting the difficulties induced by the topology aspect.     

A formal approach to automating conceptual structural design,part II: Application to floor framing generation

The function of the structural system in a building is to transfer gravity as well as lateral loads from their points of origin to the ground. Floor framing generation involves providing a path to transfer the gravity loads to the ground through various structural elements in an architectural plan while meeting the requirements imposed by other entities, such as the architect, the mechanical engineer, and the contractor, involved in the design/construct process. In this paper a formal approach for generating floor framing plans for steel office buildings is presented. We describe the knowledge and the reasoning behind a computer system, FFG (floor framing generator), which generates floor framing schemes for steel office buildings that are rectangular in plan and have a single service core. Constraints arising from structural as well as exogenous considerations are enumerated and their effect on framing schemes is identified. We also elaborate on the evaluation mechanism for ranking alternative schemes, in addition to providing details of the computer implementation.     

Singularity avoidance in robotic manipulators: A differential form approach

We examine the avoidability property of singular configurations in redundant robot kinematics. Using a differential form approach a collection of so-called reduced self-motion dynamical systems is attributed to singular configurations distinguished by coranks. The problem of detecting avoidability/unavoidability is transformed to a stability study of the reduced self-motion systems. Sufficient conditions for avoidability and unavoidability are derived.     

Synthetic on-line signature generation. Part I: Methodology and algorithms

The theoretical framework and algorithms of a novel method for the generation of synthetic on-line signatures are presented. This model-based approach combines the spectral analysis of real signatures with the Kinematic Theory of rapid human movements in order to generate totally synthetic specimens. Two different algorithms are also described in order to produce duplicated samples from the synthetic master signatures, so that the generation scheme as a whole is able to produce in a complete automatic fashion huge synthetic databases. Typical examples of synthetic specimens are presented to highlight their human-like appearance. The validation protocol and the test results are presented and discussed in a companion paper.     

An alternative structure for next generation regulatory controllers. Part II: Stability analysis,tuning rules and experimental validation

We recently developed, as an alternative to the PID controller, a novel 4-mode control scheme that takes full advantage of modern electronic hardware components, and whose tuning parameters are directly related to controller performance attributes (robustness, set-point tracking, and disturbance rejection); its achievable performance is better than that of the PID controller, and it can be designed and implemented much more directly and transparently. In this companion paper we present robust stability results for the proposed controller, for any given plant/model mismatch; these results are then used to generate simple tuning rules for the controller. The effect of noise on controller performance is explicitly considered and modified tuning rules are proposed for excessively noisy processes. The controller tuning results and procedure are then illustrated via experimental testing and validation. First, water level control in a simple laboratory scale process is used to illustrate the design, tuning, and implementation of the RTDA controller. We use this process primarily to evaluate the controller performance and illustrate how the tuning parameters influence, directly and independently, the controller performance attributes. The controller is then implemented on a pilot-scale physical vapor deposition process to demonstrate its performance on a more complicated process that is prototypical of 21st century manufacturing. We demonstrate that the proposed controller achieves improved performance with minimal tuning effort.     

Application of finitized power series distributions to accelerated variate generation. Part II: the case of the logarithmic distribution

The method of aliasing vastly expands the palette of discrete random variate generation methodologies while providing excellent speed. However, its application is limited to finitely supported distributions. We demonstrate that an application of moment preserving finitization called the Negative Taylor Series Finitization (NTSF) method for the power series family of discrete distributions, when coupled with the method of aliasing, can greatly improve infinitely supported discrete random variate generation speed with certain limitations. We illustrate this with the logarithmic power series distribution, and we compare four published algorithms designed to generate random variates from a logarithmic distribution to the aliasing method of random variate generation from an NTSF version of the same distribution. We compare the accuracy and speed (user‐time) of these various methods for generating variates from a logarithmic distribution.     

Aspect-oriented model-driven skeleton code generation: A graph-based transformation approach

Model-driven code generation has been investigated in traditional and object-oriented design paradigms; significant progress has been made. It offers many advantages including the rapid development of high quality code. Errors are reduced and the consistency between the design and the code is retained, in comparison with a purely manual approach. Here, a model-driven code generation approach based on graph transformations for aspect-oriented development is proposed. The approach has two main transformation activities. The first activity transforms a visual (graphical) model of the design into a formal, text-based notation that can be readily processed. The graphical model is created by the software designer and uses a UML profile for aspect-oriented software (i.e., FDAF) to represent aspects and their components. XML is the target notation for this step; the transformation uses the XML meta-model to ensure that the output complies with the language. The second activity transforms the XML model into AspectJ source code. The transformation uses the AspectJ meta-model to ensure the output complies with the language. The transformations from the extended UML model to XML and from XML to AspectJ code are fully automated. The transformation algorithms are based on graph transformations; tool support has been developed. Key technical issues in the approach are discussed, including performance, the amount of code generated, correctness, and adaptability, in addition to a comparison of the proposal with existing alternative approaches. The approach has been validated on three example systems: a banking system, classroom scheduling system, and an insurance system. The banking system example is presented in the paper.     

Self-sensing for electromagnetic actuators. Part I: A coupled reluctance network model approach

A self-sensing arrangement in active magnetic bearings (AMBs) comprises a single electromagnetic transducer to realize the actuation and sensing functions concurrently. Minimizing the number of sensing devices and associated interfacing directly reduces possible failure points, system costs, and system complexity. Currently, self-sensing performance is degraded due to problems such as magnetic cross-coupling, eddy currents, saturation, and high losses. This first paper in a two part series presents an integrated model for self-sensing of an 8-pole heteropolar magnetic bearing. The proposed self-sensing approach addresses mechanisms that contribute to modelling error and uncertainty by using several techniques in an integrated structure. A coupled reluctance network model (RNM) is developed which models the coil impedance at the switching frequency. The accuracy of the model is improved by incorporating terms for air gap fringing, complex permeability, and magnetic material nonlinearity. The RNM is verified and refined through a process of iteration using finite element method (FEM) results and experimental AMB measurements. The results demonstrate that a RNM with only 40 nodes can achieve high levels of accuracy when compared to an 80 000 node FEM analysis.In Part II of the series, the refined RNM is incorporated into a multiple input multiple output (MIMO) parameter estimation self-sensing scheme.     

A novel approach of three-dimensional hybrid grid methodology: Part 2. Flow solution

Following the previous paper of this series, which addresses the generation approach of three-dimensional DRAGON grids, we demonstrate the capability of effectively performing three-dimensional flow calculations for multi-components complex configurations. The flow solution is conducted by means of using a seamlessly integrated package made up of two well-validated NASA solvers, which are structured- and unstructured-grid codes, respectively.