Author Keywords: Multivariable systems; Flatness control; Rolling mills; Observers 相似文献
• • The finite element method is used for qualitative comparison of different machine tool structure concepts during the conceptual and design stages. Only after completion of the prototype may the parameters of the prototype model be adjusted for the purpose of obtaining quantitative indicators.
• • Dynamics are analyzed by parameter identification of the oriented transfer function model. The dominant degree of freedom is naturally selected by experiment and not from hypotheses about the behavior of structures obtained from mathematical manipulations such as expansion of the model according to the finite element method. If necessary another machine tool structure may be modelled; in this way hypotheses are drawn about the stability of the reconstructed prototype.
Such a procedure has been applied and verified on the machine tool structure of a horizontal machining center. Results for static rigidity and dynamic stability have been obtained from the model and experiments performed on the prototype. The following techniques have been used:
• • finite element method for qualitative identification of static behavior,
• • self-excitation of the machine,
• • digital signal processing on the FFT basis,
• • smoothing of curves and digital filtration,
• • function fitting of the transfer function (modal analysis),
• • coefficient calculus and oriented transfer function,
• • stability assessment of the fitted model under different machining conditions, and
• • modelling of the regenerative machining effect by cutting.
Necessary tests have been done by instruments required for the use of the above techniques.
Such a combined static-dynamic criteria procedure for structuring a machine tool enables efficient follow-up of all results and facilitates necessary future expansion, the utilization of universal equipment, the combination of modelling and experiments, and the synthesis of simple models of the examined machine with behavior identical to the machine. The well-known machining system dynamic stability theories are applied to such models. 相似文献
1. (a) The development of the mathematical models for each of the elements of the heating system;
2. (b) Combining the mathematical models into a form which is suitable for the application of optimization techniques;
3. (c) Defining an optimization criterion which incorporates the main objective for minimizing room temperature variations with respect to a prescribed reference temperature;
4. (d) Choosing the optimization technique best suited for the problem;
5. (e) Constructing an optimal control system employing the optimization technique developed.
A numerical example compares the performance of the optimal system with a system of the conventional type which can be found in many American homes. 相似文献
1. (i) canonical forms for state space equivalence of minimal systems and
2. (ii) canonical forms for state space equivalence of asymptotically stable minimal systems.
Implications for the topology of various sets of asymptotically stable systems are given. 相似文献
1. (1) The structure of the controller is simple. This makes it easy to tune the control system.
2. (2) The controller copes well with the detection time delay, and thus high performance is obtained even at a low rolling speed.
3. (3) The flatness error caused by the rolling force variation in mill acceleration and deceleration time would be kept to a minimum by the function to adjust roll bending force using the signal of rolling force.
1. (1) fuzzy representation;
2. (2) hierarchical performance evaluation structure,
3. (3) gradient eigenvector method for rating the fuzzy criteria weighting, and
4. (4) using the max-min paired elimination method for aggregation.
To illustrate the approach, an example on the evaluation of teaching performance in higher education is solved. 相似文献
1. (1) navigate the robot between an initial and a final position of the warehouse, and
2. (2) construct a clearing (path) between two specified points.
The final positions of the obstacles are unimportant for our problems.
We consider two forms of obstacle manipulations:
1. (a) remote, when the obstacles are moved by a remote mechanism, and
2. (b) contact, when the obstacles are moved only by direct contact of the robot.
We present necessary and sufficient conditions for the existence of a motion in both cases, and propose efficient algorithms for constructing feasible motions. 相似文献
1. 1. Applications of the entity-relationship approach to knowledge representation.
2. 2. The basic philosophy of expert database systems and
3. 3. Integration of manufacturing systems from the above two concepts.
The approaches for 1 and 2 are explained with actual implementation experiences, while a framework for integration is proposed from a more philosophical perspective. 相似文献
A major theme of the proposed paper is the investigation of the combinatorial structure of the visibility graph. More importantly, the goals of this paper are:
1. (i) To characterize the visibility graphs of simple polygons by obtaining necessary and sufficient conditions a graph must satisfy to qualify for the visibility graph of a simple polygon
2. (ii) To obtain hierarchical relationships between visibility graphs of simple polygons of a given number of vertices by treating them as representing simple polygons that are deformations of one another.
3. (iii) To exploit the potential of complete graphs to be natural coordinate systems for addressing the problem of reconstructing a simple polygon from visibility graph.
We intend to achieve this by defining appropriate “betweenness” relationships on points with respect to the edges of the complete graphs. 相似文献
1. 1. Participate in the evaluation of proposed FMS systems,
2. 2. Assess the impact of FMS acquisition on existing facilities,
3. 3. Assist in the identification of operational alternatives in “bottle neck” situations.
The pilot study employs a batch-oriented MRP system to provide daily updates of outstanding production center loadings on a monthly planning horizon. Two intelligent terminals are used to access a mini computer facility that executes the simulation models. The terminals have AT-compatible capabilities and are also used as data acquisition devices that support the numerically controlled operations within each work center.
The simulation models represent the 13 work centers of the firm and provide information about the average utilization of each work center, the number of parts in each queue and the average delay of parts in the queues. Future extensions of the models are planned to utilize the terminals' graphic animation capabilities to display the flow of production orders through the manufacturing facility. 相似文献
- (A) Efforts to extend the Curry–Howard isomorphism, established between the simply-typed lambda calculus and intuitionistic logic, to classical logic.
(B) Efforts to establish the tacit conjecture that call-by-value (CBV) reduction in lambda calculus is dual to call-by-name (CBN) reduction.
Keywords: Dual Calculus; Classical lambda calculi; Curry–Howard isomorphism; Continuations 相似文献
- (1) Seventy-three percent of journal papers focus on 20% of subject indexes in software engineering, including Testing and Debugging (D.2.5), Management (D.2.9), and Software/Program Verification (D.2.4).
(2) Eighty-nine percent of conference papers focus on 20% of subject indexes in software engineering, including Software/Program Verification (D.2.4), Testing and Debugging (D.2.5), and Design Tools and Techniques (D.2.2).
(3) Seventy-seven percent of journal/conference papers focus on 20% of subject indexes in software engineering, including Testing and Debugging (D.2.5), Software/Program Verification (D.2.4), and Management (D.2.9).
(4) The average number of references cited by a journal paper is about 33, whereas this number becomes around 24 for a conference paper.
Keywords: Software engineering; Research topics; Subject indexes; Top journals; Top conferences 相似文献
The programming system used as an example in this article consists of
1. *NORSAM—finite element programming system
2. *DASA — pre- and postprocessors
3. *ELLIB—element library
Together they form a complete set of subroutines from datageneration through the necessary routines for matrix manipulation to presentation of results, including the multilevel superelement technique.
Reference to finite element programs applying the programming system concept, is given at the end of the article. Among others, programs for buckling, elasto-plastic analysis of 3-dimensional membranes and solids, nonlinear pipeline problems, acoustic field problems and transient heat conduction in solids are developed. The multilevel superelement technique has been applied in several of these application programs.
The concept of the programming system gives undoubtedly a large saving of time and resources and has proved to be more reliable than conventional methods when developing finite element programs. 相似文献
1. (1) For which classes of graphs is it possible to specify a linear ordering of the set of vertices of each graph of by fixed monadic second-order formulas?
2. (2) For which classes of graphs does there exist an extension of monadic second-order logic such that a subclass L of is recognizable if and only if it is the class of graphs in that satisfy a formula of ? (In this paper, recognizability is understood in an algebraic sense, relative to a finite set of graph operations and basic graphs that generate all graphs of .)
3. (3) For which classes of graphs is it possible to construct, in every graph of the class, and by fixed formulas of a suitable extension of monadic second-order logic, its hierarchichal structure, i.e., a finite term written with the operations and basic graphs of (2), that defines the considered graph?
Applications concern dependency graphs of partially commutative words, partial k-paths, cographs, and graphs, the modular decomposition of which uses prime graphs of bounded size. 相似文献
1. • for curve tracing algorithms, where a truncated series is used to approximate the curve of intersection of two surfaces
2. • to define nth degree geometric continuity, for arbitrary
Author Keywords: power series; curve; surface; intersection problems; curve tracing; geometric continuity 相似文献
1. 1. Over three-quarters of workers were more satisfied in S/P jobs, while only less than one-quarter were more satisfied in M/P jobs.
2. 2. The 16PF personality test effectively predicts (0·88 multiple correlation) the satisfaction ratios of M/P to S/P jobs.
Author Keywords: Production processes; job satisfaction; assembly line 相似文献