The essence and complicacy of approach to computer design of an optimal pulsed arc welding technology is that programmed periodic action should be developed on the one hand to exert its effect on melting and transfer ...
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ISBN:
(纸本)0878499199
The essence and complicacy of approach to computer design of an optimal pulsed arc welding technology is that programmed periodic action should be developed on the one hand to exert its effect on melting and transfer of an electrode metal, and on the other hand, to control over the molten pool fluidity, the structural formation of weld and heat-affected zone that appears as result of the weld pool crystallization whilst ensuring stability of the pulsed regime in welding in different spatial positions. The results of physical simulation and mathematical modelling permit to design optimal algorithms of pulsed control of energy characteristics of welding-arc current and voltage, arc heated efficiency, peak short-circuiting current. The results of computer experiments permit to establish pulsed welding controlled parameters-service properties of welded joints (such as the sizes of welds and heat-affected zone, quality and strength properties of welded joints) relation.
A new method for identifying dynamic parameters of a structure by measuring its first several frequencies and mode shapes is presented in this paper. Accurate estimates of the dynamic characteristics of a structure us...
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ISBN:
(纸本)0819448621
A new method for identifying dynamic parameters of a structure by measuring its first several frequencies and mode shapes is presented in this paper. Accurate estimates of the dynamic characteristics of a structure using limited measurement data are necessary for applications such as damage localization and finite element model verification. This method is developed from the unconstrained simplex method by introducing some practical constraint conditions. The approach is not limited by either the minimum order of required eigenvalue and eigenvector pairs or the completeness of each order, for instance, even only a subset of frequencies or mode shapes are sufficient for a given order to yield acceptable identification results. Two numerical examples for identifying the stiffness distribution of a ten-story shear building under different health conditions are provided. The identified stiffness agrees with the physical model quite well. It is shown that this method has the advantages of good accuracy in calculation and great potentiality for most applications in similar structures or areas due to the fact that it is not only very robust but also not so strict with measurement methods and the amount of required information in field tests.
A time scale can be regarded as a synthesis of readings from precise clocks. Usually such synthesis is based on the principle of weighted averaging, which balances the contribution of each clock according to its noise...
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A time scale can be regarded as a synthesis of readings from precise clocks. Usually such synthesis is based on the principle of weighted averaging, which balances the contribution of each clock according to its noise level. It is well known that there are five different noise processes in precise clocks. Therefore, a good synthesis should balance each of those noise levels, Most existing algorithms control only one or two noise types. If an algorithm can control all five noise types simultaneously, we consider it to be optimum. The key point of constructing an optimum algorithm is the separation of all five noise types. In this paper, an optimum algorithm is presented using the half-integrating/half-differentiating model by which. the five noise types are separated correctly. Performances of the new algorithm are demonstrated with simulated and real data.
In this paper, we discuss the problem of covering a convex rectilinear polygon with the minimum number of rectangles. The rectangles can overlap with each other. We show that this problem can be solved in linear time,...
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In this paper, we discuss the problem of covering a convex rectilinear polygon with the minimum number of rectangles. The rectangles can overlap with each other. We show that this problem can be solved in linear time, which improves the previous O(n(2)) result proposed by Franzblau and Kleitman(3). However, Franzblau and Kleitman's algorithm works for a larger class of polygons (vertically convex).
An algorithm is presented which finds all occurrences of one given string within another, in running time proportional to the sum of the lengths of the strings. The constant of proportionality is low enough to make th...
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An algorithm is presented which finds all occurrences of one given string within another, in running time proportional to the sum of the lengths of the strings. The constant of proportionality is low enough to make this algorithm of practical use, and the procedure can also be extended to deal with some more general pattern-matching problems. A theoretical application of the algorithm shows that the set of concatenations of even palindromes, i.e., the language {αα
pattern
string
text-editing
pattern-matching
trie memory
searching
period of a string
palindrome
optimum algorithm
Fibonacci string
regular expression
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