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Found 6273 publications

Influence of weediness on sugar beet yields

Péter Bosák Katalin Lajos

Publication Name: Novenytermeles

Publication Date: 1999-12-01

Volume: 48

Issue: 6

Page Range: 617-629

Description:

The influence of weeds on yield and quality were studied in sugar beet stands kept mechanically weedless for different periods in small-plot. Plots which were weeded early in the season (1st May or 15th May) and were kept clean to the end of the growing period (30th September) gave significantly higher and better quality yield than plots where weed killing started later (1st June) or where the weeds were allowed to reappear after 15th May or 1st June. Trials proved that weed control in sugar beet has to be started early and that the stand has to be kept weedless to the end of the growing period. The late spread of weeds is an important yield-reducing factor.

Open Access: Yes

DOI: DOI not available

Calculation of the optimal shape of nonconical dies by minimizing necessary forces

Erno Halbritter G. Y. Molnarka

Publication Name: Advances in Engineering Software

Publication Date: 1999-09-15

Volume: 30

Issue: 9-11

Page Range: 735-740

Description:

A mathematical model is given for the metal forming in an axisymmetric nonconical converging die. By using the Maple V system a semianalytical algorithm is proposed for the calculation of the optimal shape of the die which minimizes the consumed energy of the deformation and the power of the friction forces at the wall. Two examples are presented to demonstrate the efficiency of the proposed method. © 1999 Elsevier Science Ltd and Civil-Comp Ltd. All rights reserved.

Open Access: Yes

DOI: 10.1016/S0965-9978(98)00117-3

Hausdorff dimension of univoque sets

Gabor Kallos

Publication Name: Acta Cybernetica

Publication Date: 1999-01-01

Volume: 14

Issue: 2

Page Range: 303-314

Description:

In this paper we present the results obtained so far for the determination of the Hausdorff dimension of the univoque set, in number systems with base number greater than 1. The investigation is based on the methods presented in [1] and [2]. We illustrate the theoretical results with interesting examples.

Open Access: Yes

DOI: DOI not available

The effect of the matrix condition number on the estimate of core barrel motion

M. Berta G. Pór

Publication Name: Progress in Nuclear Energy

Publication Date: 1999-01-01

Volume: 34

Issue: 1

Page Range: 1-11

Description:

It is shown, that the matrix condition number plays determining role in the error of estimation of core barrel motion when using the well known spectral decomposition methods. Matrix condition numbers were estimated for different type of reactors and detector arrangements. It is shown that in unfortunate case the statistical error of estimate can reach hundreds of the original statistical error. It is suggested to eliminate one of the freedom of the system, before making spectral decomposition, which can drastically improve the accuracy of the decomposition. © 1998 Elsevier Science Ltd. All rights reserved.

Open Access: Yes

DOI: 10.1016/s0149-1970(97)00110-8

On the Schur component preconditioners

Béla Kiss A. Krebsz

Publication Name: Computers and Structures

Publication Date: 1999-01-01

Volume: 73

Issue: 1-5

Page Range: 537-544

Description:

Some representations of the H 1/2 norm are used as Schur complement preconditioners in PCG-based domain decomposition algorithms for elliptic problems. These norm representations are efficient preconditioners. Here we give a new matrix representation of the Ha (0 < a < 1) norms by a special sparse Toeplitz matrix. It contains O(log(N)) non-zero entries at each row, where N is the number of rows. The special properties of this matrix ensure that it can be used as preconditioner. This is proved by estimating spectral equivalence constants and this fact has also been verified by numerical tests.

Open Access: Yes

DOI: 10.1016/S0045-7949(98)00258-2

Multigrid technique for biharmonic interpolation with application to dual and multiple reciprocity method

Csaba Gáspár

Publication Name: Numerical Algorithms

Publication Date: 1999-01-01

Volume: 21

Issue: 1-4

Page Range: 165-183

Description:

A biharmonic-type interpolation method is presented to solve 2D and 3D scattered data interpolation problems. Unlike the methods based on radial basis functions, which produce a large linear system of equations with fully populated and often non-selfadjoint and ill-conditioned matrix, the presented method converts the interpolation problem to the solution of the biharmonic equation supplied with some non-usual boundary conditions at the interpolation points. To solve the biharmonic equation, fast multigrid techniques can be applied which are based on a non-uniform, non-equidistant but Cartesian grid generated by the quadtree/octtree algorithm. The biharmonic interpolation technique is applied to the multiple and dual reciprocity method of the BEM to convert domain integrals to the boundary. This makes it possible to significantly reduce the computational cost of the evaluation of the appearing domain integrals as well as the memory requirement of the procedure. The resulting method can be considered as a special grid-free technique, since it requires no domain discretisation.

Open Access: Yes

DOI: 10.1023/a:1019173816678

Mechanics and energetics, the complex analysis of an industrial problem with the tools of up-to-date computer methods

I. Zsenak J. Egert F. Zsenak

Publication Name: Proceedings of the Conference on Mechanical Engineering

Publication Date: 1998-12-01

Volume: 2

Issue: Unknown

Page Range: 805-810

Description:

The arc furnaces are widely used to melt different kind of materials on high temperature. In the steel and the aluminum factories the so-called gurgling type Heroult furnaces are used. The shell's geometry an the used arc's parameters are the function of the local expectations. The most of the arcs agree on that the water taking up released heat during the melting goes out to channels or cooling towers, leaving the energy non-utilized.

Open Access: Yes

DOI: DOI not available

Test on railway vehicle-runway dynamic system for stress analysis of a carriage's body

Emil Halmos László Bozóky Vince Nagy Zoltan Varga

Publication Name: Proceedings of the Mini Conference on Vehicle System Dynamics Identification and Anomalies

Publication Date: 1998-12-01

Volume: Unknown

Issue: Unknown

Page Range: 115-122

Description:

Damages at vehicle bodies required an analysis to qualify the vehicle-runway system. The aim of the analysis is to declare critical effects and show the possible and necessary measurements. The running tests on the vehicle had many objects. Effects of waveform could be seen in the spectral density functions for vehicles running on runway with waved rail wearing. Effects of waveforms were found to be little on the mechanical stresses of vehicle body. The curve of the runway has major effect on the values of the mechanical stresses.

Open Access: Yes

DOI: DOI not available

Test on railway vehicle-runway dynamic system for stress analysis of a carriage's body

No authors available

Publication Name: Proceedings of the Mini Conference on Vehicle System Dynamics, Identification and Anomalies

Publication Date: 1998-12-01

Volume:

Issue:

Page Range: 115-122

Description:

Damages at vehicle bodies required an analysis to qualify the vehicle-runway system. The aim of the analysis is to declare critical effects and show the possible and necessary measurements. The running tests on the vehicle had many objects. Effects of waveform could be seen in the spectral density functions for vehicles running on runway with waved rail wearing. Effects of waveforms were found to be little on the mechanical stresses of vehicle body. The curve of the runway has major effect on the values of the mechanical stresses.

Open Access: No

DOI: DOI not available