Constraint logic programming for the analysis and partial synthesis of truss structures

Constraint Logic Programming (CLP) languages extend logic programming by allowing the use of constraints from different domains such as real numbers or Boolean functions. They have proved to be ideal for expressing problems that require interactive mathematical modeling and complex combinatorial optimization problems. However, CLP languages have mainly been considered as research systems, useful for rapid prototyping, by not really competitive with more conventional programming languages where efficiency is a more important consideration. One promising approach to improving the performance of CLP systems is the use of powerful program optimizations to reduce the cost of constraint solving. We extend work in this area by describing a new optimizing compiler for the CLP language CLP(ℛ). The compiler implements six powerful optimizations: reordering of constraints, removal of redundant variables, and specialization of constraints which cannot fail. Each program optimization is designed to remove the overhead of constraint solving when possible and keep the number of constraints in the store as small as possible. We systematically evaluate the effectiveness of each optimization in isolation and in combination. Our empirical evaluation of the compiler verifies that optimizing compilation can be made efficient enough to allow compilation of real-world programs and that it is worth performing such compilation because it gives significant time and space performance improvements.

The incorporation of global program analysis into recent compilers for Constraint Logic Programming (CLP) languages has greatly improved the efficiency of compiled programs. We present a global analyser based on abstract interpretation. Unlike traditional optimizers, whose designs tend to be ad hoc, the analyser has been designed with flexibility in mind. The analyser is incremental, allowing substantial program transformations by a compiler without requiring redundant re-computation of analysis data. The analyser is also generic in that it can perform a large number of different program analyses. Furthermore, the analyser has an object-oriented design, enabling it to be adapted to different applications easily and allowing it to be used with various CLP languages with simple modifications. As an example of this generality, we sketch the use of the analyser in two different applications involving two distinct CLP languages: an optimizing compiler for CLP(R) programs and an application for detecting occur-check problems in Prolog programs. © 1998 John Wiley & Sons Ltd.

In recent years, several constraintdbased temporal reasoning frameworks have been proposed. They consider temporal points or intervals as domain elements linked by temporal constraints. Temporal reasoning in these systems is based on constraint propagation. In this paper, we argue that a language based on constraint propagation can be a suitable tool for expressing and reasoning about temporal problems. We concentrate on Constraint Logic Programming (CLP) which is a powerful programming paradigm combining the advantages of Logic Programming and the efficiency of constraint solving. However, CLP presents some limitations in dealing with temporal reasoning. First, it uses an “arc consistency” propagation algorithm which is embedded in the inference engine, cannot be changed by the user, and is too weak in many temporal frameworks. Second, CLP is not able to deal with qualitative temporal constraints. We present a general meta CLP architecture which maintains the advantages of CLP, but overcomes these two main limitations. Each architectural level is a finite domain constraint solver (CLP(FD)) that reasons about constraints of the underlying level. Based on this conceptual architecture, we extend the CLP(FD) language and we specialize the extension proposed on Vilain and Kautz’s Point Algebra, on Allen’s Interval Algebra and on the STP framework by Dechter, Meiri and Pearl. In particular, we show that we can cope effectively with disjunctive constraints even in an intervaldbased framework.

In this paper, we show a validity of a new programming paradigm called constraint logic programming by constructing a robot structure design support system. The design process of a robot structure is divided into a fundamental structure design and a internal structure design. A fundamental structure design is a process that determines a framework of the robot such as a degree of freedom, a number of joint, etc. We mainly support a fundamental structure design. This design system is constructed by constraint logic programming language. The Buchberger algorithm is used to calculate the nonlinear equation in this language. Our design system generates an analysis program independent of robot structure easily. The result of analysis is also gotten in the form of expression. The constraint can be appended incrementally. By constructing such a system, we can achieve remarkable reduction of designer's work in design process.

Constraint logic programming (CLP) has demonstrated its ability to handle difficult problems coming from operation research. We think that this approach is relevant to perform program analyses too. However, program analysis often requires solvers for second order constraints, i.e. mainly fixpoint equations, that are not available in CLP languages. In this paper, we present, the language Toupie that is designed to solve such constraints. Toupie uses an extension of Bryant's binary decision diagrams to encode relations which makes it possible to handle relations with huge numbers of elements.

CAL: A theoretical background of constraint logic programming and its applications

Despite of the fact that in the title the analysis of two-dimensional structures is indicated, we shall be concerned with three-dimensional structures made from composite non-homogeneus anisotropic linear visco-elastic materials. The problem considered is a quasi-static one in which inertia forces due to deformation could be neglected.

We have described the constraint logic programming language CS-Prolog. CS-Prolog is written in PROLOG about 1,500 lines. This is a very small as oppose to similar system CLP which is written in C about 12,000 lines, but less efficient than CLP. However, CS-Prolog solves equations and inequations in reasonable time and this paper shows the simple approach to constraint logic programming using PROLOG and this technique is very useful for constraint logic programming language system on top of PROLOG machine.

The concept of Expert Decision Support Systems is based on the integration of Decision Support Systems and Expert Systems, providing the decision maker with features from both types of systems (e.g. simulation, explanations, control of reasoning). Constraint logic programming languages, such as CLP(R) or CHIP, achieve this integration by merging logic programming, a paradigm of Artificial Intelligence and Expert Systems, with constraint solving techniques similar to those used in Operations Research and Decision Support Systems. Their embedded constraint solver extends the expressive power of logic programming languages, most notably on the domain of numerical expressions. The paper illustrates how constraint logic programming may be used in EDSS development by presenting a small classroom scheduling problem developed with CLP(R), and compares this approach to more traditional Operations Research techniques.

In this paper, we present the constraint language Toupie which is a finite domain μ-calculus interpreter that uses extended decision diagrams to represent relations and formulae. “Classical” constraint logic programming languages over finite domains (CLP(FD)) are designed to find one solution to a constraint problem, eventually the best one according to a given criterion. In Toupie, constraints are used to characterize existing relationships between variables. We advocate the use of this paradigm to model and solve efficiently difficult constraint problems that are not tractable with CLP(FD) languages.KeywordsSymbolic Model CheckingConstraint Languages

According to design drawings of an escalator truss, the solid model of escalator truss is established, and the finite element analysis model is built up. Based on the finite element model, strength and stiffness of escalator truss structure is checked according to the application criterions. In order to get more accurate stress results of escalator truss structure, the load conditions and constrains are carefully considered, and the analysis results are more realistic. In order to avoid resonance, modal analysis of truss structure is carried out. The results show that the strength and stiffness of the escalator truss meets the national standard. The main excitation frequencies of the escalator truss are avoided in all modes, and the resonance of the escalator will not occur during operation.

This paper presents new techniques in two different areas. Firstly, it proposes a solution to the problem of testing embedded processors. Towards this end, it discusses the automatic generation of executable test programs from a specification of test patterns for processor components. Secondly, the paper shows how constraint logic programming (CLP) improves the software production process for design automation tools. The advantages of CLP languages include: built-in symbolic variables and the built-in support for constraints over finite domains such as integers and Booleans.

It is difficult to solve the structural problems related to agricultural engineering, due to the wide ranges of the means of related variables and complex structural shapes. For these reasons, discrete models are required that are able to replace or simplify solid structure components used in traditional analysis methods. Therefore, the objective of this study was to develop a regular truss structure model that behaves the same way as a solid structure. It was assumed that if a unit element consists of truss elements with each hinge at the end of the element and the size of the element is infinitesimal, the stress distribution and displacement field will be constant throughout the domain of the unit element. Additionally, the behavior of the truss element was assumed to be in a linear state in a two-dimensional plane. The law of energy conservation, based on the theory of elasticity, was applied to determine the equilibrium conditions between discretized and solid elements. The restrictive condition that we obtained revealed that applications are limited to only ideal elastic materials with a Poisson’s ratio of 1 to 3. The volumetric ratio of the equivalent truss to the continuum structures was 3:1, regardless of the size or number of the mesh. To calculate the internal stress and strain of the unit element, the geometric relationships of each truss member, which has its own role against different stress directions, were used. The calculated von Misses stresses were used to verify this model. Stress concentrations, as explained based on Saint Venant’s principle, were also observed in the equivalent truss structure model. The main stress paths, indicating the areas where reinforcement bars should be placed, were successfully shown without the requirement that each element be transformed in the direction of principal stress; this was done by eliminating elements with only compressive and near-zero stresses. Keywords: structural analysis, regular mesh, equivalent truss structure model, discretized element, energy method DOI: 10.3965/j.ijabe.20150805.1742 Citation: Choi W, Lee J, Yoon S. Regular truss structure model equivalent to continuum structure. Int J Agric & Biol Eng, 2015; 8(5): 151－161.

A logic-based approach for automating the processing of design standards is illustrated. This approach is composed of three steps: conceptualization, formalization and implementation. Conceptualization is referred to as the representation of the knowledge necessary for solving the problem of interest in terms of objects and relations. Formalization is referred to as the representation of the objects and relations of interest as axioms using the language of predicate calculus. And, Implementation is referred to as the representation of the axioms of interest and the strategy for manipulating axioms using the constructs of a programming language.The paper illustrates the logic-based approach to engineering problem-solving automation by considering the portion of the AISC Specification that governs the design of axially loaded members. First, the relations of interest are identified (Conceptualization). Then, predicate calculus is used to formally represent the relations (Formalization) as axioms and to mechanically manipulate them. The checking and designing of structural components via mechanical manipulation of the axioms are illustrated in the paper. Finally, a constraint logic programming language is used to develop a computer program for automatic processing of the specification (Implementation). This program is composed of a set of rules that closely resemble the formulated axioms.

Object-oriented structural and geometric analysis methods for truss structures are proposed. The methods are based on the iterative relaxation of nodal unbalanced forces by moving the nodes. The entities appeared in truss analysis are modeled as classes, and their class hierarchy is established. The knowledge about a truss node, a truss member, a material, and a sectional shape of the member are extracted and constructed as a knowledge base in an object-oriented manner. The object-oriented structural analysis is found to be valid for material and geometric nonlinearities, and the object-oriented geometric analysis where a kinematic problem is converted into a problem for a force equilibrium at the nodes is also found to be effective for determining the geometry of variable geometry trusses. The whole system is written in an object-oriented language, Smalltalk, and several results on structural and geometric analysis are presented. The speed of the computation is discussed along with the size of the structures and the over-relaxation factor. The extension of the knowledge base is also discussed.