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Mathematical and Computational Applications is published by MDPI from Volume 21 Issue 1 (2016). Previous articles were published by another publisher in Open Access under a CC-BY (or CC-BY-NC-ND) licence, and they are hosted by MDPI on mdpi.com as a courtesy and upon agreement with the previous journal publisher.

Math. Comput. Appl., Volume 9, Issue 3 (December 2004) – 17 articles , Pages 333-494

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2281 KiB  
Article
Variational Monte Carlo Calculations of Energy per Particle Nuclear Matter
by K. Manisa
Math. Comput. Appl. 2004, 9(3), 485-494; https://doi.org/10.3390/mca9030485 - 1 Dec 2004
Viewed by 1054
Abstract
In this paper, symmetrical nuclear matter has been investigated. Total, kinetic and potential energies per particle were obtained for nuclear matter by Variational Monte Carlo method. We have observed that the results are in good agreement with those obtained by various authors who [...] Read more.
In this paper, symmetrical nuclear matter has been investigated. Total, kinetic and potential energies per particle were obtained for nuclear matter by Variational Monte Carlo method. We have observed that the results are in good agreement with those obtained by various authors who used different potentials and techniques. Full article
2694 KiB  
Article
A New Encoding Decoding Scheme for Text Compression with Embedded Security
by Ebru Celikel and Mebmet E. Dalkilic
Math. Comput. Appl. 2004, 9(3), 475-484; https://doi.org/10.3390/mca9030475 - 1 Dec 2004
Cited by 1 | Viewed by 1246
Abstract
In today's communication world, finding out and improving the means of better channel utilization, as well as providing the security of data transmitted are the key issues. For some data types, e.g. text, full (lossless) data recovery might also be required. Therefore, a [...] Read more.
In today's communication world, finding out and improving the means of better channel utilization, as well as providing the security of data transmitted are the key issues. For some data types, e.g. text, full (lossless) data recovery might also be required. Therefore, a lossless compression algorithm that is reasonably fast and secure enough would meet the needs of many in the networking environments. While standard compression tools (e.g. gzip of Unix and pkzip of Windows platforms) achieve compression rates at around 3 bpc (bits per character) for text type of data, they are poor at security. This study presents the design and implementation of a new encoding/decoding scheme to offer compression and security at the same time. For that, the scheme combines compression with encryption. To address the security issue, encoding is made through an Encoding matrix generated by a Pseudo Random Number Generator. This encoding already provides an initial compression. It then uses Arithmetic Coding to further compress the text. For further security, an iterative encoding scheme is proposed and implemented. The results obtained are encouraging in terms of both compression and security. Full article
2958 KiB  
Article
233U Breeding in a Modified Prometheus-L IFE Reactor
by Mustafa Übeyli
Math. Comput. Appl. 2004, 9(3), 463-473; https://doi.org/10.3390/mca9030463 - 1 Dec 2004
Viewed by 1073
Abstract
In this study. neutronic analysis of a hybrid version of the PROMETHEUS-LIFE reactor is investigated by using thorium fuels namely, ThN, ThC2 and ThF4. Calculations of neutronic data per DT fusion neutron are performed by using SCALE 4.3 Code. Despite [...] Read more.
In this study. neutronic analysis of a hybrid version of the PROMETHEUS-LIFE reactor is investigated by using thorium fuels namely, ThN, ThC2 and ThF4. Calculations of neutronic data per DT fusion neutron are performed by using SCALE 4.3 Code. Despite a partial replacement of the tritium breeding zone by the fissile fuel breeding zone, tritium breeding remains still > 1.05, which will be required for a self-sustaining fusion driver. Energy multiplication 1.44 to 1.50 depending on the fuel types in the blanket. Therefore, the investigated reactor can produce substantial electricity in situ. Substantial amount of fissile material will be produced at start-up conditions with a fissile fuel breeding rate of 233U = 0.154, 0.126 and 0.077 for ThN, ThC2 and ThF4 per incident fusion neutron, which correspond to 1858, 1521, 934 kg 233U/year, respectively, by a full fusion power of 2807 MW. Full article
1420 KiB  
Article
Informativeness of Parallel Kalman Filters
by Chingiz Hajiyev
Math. Comput. Appl. 2004, 9(3), 457-462; https://doi.org/10.3390/mca9030457 - 1 Dec 2004
Viewed by 1036
Abstract
This article considers the informativeness of parallel Kalman filters. Expressions are derived for determination of the amount of information obtained by additional measurements with a reserved measurement channel during processing. The theorems asserting that there is an increase in the informativeness of Kalman [...] Read more.
This article considers the informativeness of parallel Kalman filters. Expressions are derived for determination of the amount of information obtained by additional measurements with a reserved measurement channel during processing. The theorems asserting that there is an increase in the informativeness of Kalman filters when there is a failure-free reserved measurement channel are proved. Full article
1879 KiB  
Article
Effects of the Weld Electrode on the Fracture Behavior of Welded Steel Beam-to-Column Joints
by Binnur Gören Kiral
Math. Comput. Appl. 2004, 9(3), 449-456; https://doi.org/10.3390/mca9030449 - 1 Dec 2004
Cited by 2 | Viewed by 1037
Abstract
Crack-like defect occurs in the weld region or heat-affected-zone of beam-to-column connections widely. They may cause unexpected serious damage in the steel welded buildings. Most of these place at the connection where the column flange meets the beam bottom flange. The assessment of [...] Read more.
Crack-like defect occurs in the weld region or heat-affected-zone of beam-to-column connections widely. They may cause unexpected serious damage in the steel welded buildings. Most of these place at the connection where the column flange meets the beam bottom flange. The assessment of these defects is entirely related to the reliability of the whole structure. In this study, the fracture behavior of the welded steel structure including the defects subjected to loading has been investigated, and the conditions free from brittle fracture hive been tried to carried out using the SINTAP Defect Assessment Procedure. The effects of the weld electrodes on the fracture behavior of the structure have been observed. Full article
1473 KiB  
Article
Effect of the Side Walls on the Unsteady Flow in a Duct of Rectangular Cross-Section
by M. Emin Erdogan and C. Erdem Lmrak
Math. Comput. Appl. 2004, 9(3), 443-448; https://doi.org/10.3390/mca9030443 - 1 Dec 2004
Cited by 1 | Viewed by 1280
Abstract
In this paper, the effects of the side walls on the unsteady flow in a duct of rectangular cross-section are considered. In order to show the effects of the side walls on the flow, two illustrative examples are given. One of them is [...] Read more.
In this paper, the effects of the side walls on the unsteady flow in a duct of rectangular cross-section are considered. In order to show the effects of the side walls on the flow, two illustrative examples are given. One of them is the unsteady flow due to an applied pressure gradient in a duct of rectangular cross-section. The other is the unsteady flow in a duct of rectangular cross-section moving parallel to its length. These effects depend on the values of the aspect ratio. The variations of the velocity and the volume flux with respect to the aspect ratio show that these are appreciable effects of the walls on the flow. It is found that the required time to reach the steady-state for the flow with side walls is shorter than that for the flow without side walls. Full article
1614 KiB  
Article
Flow Calculations in Straight-Through Labyrinth Seals by Using Moody's Friction-Factor Model
by Yilmaz Dereli and Dursun Eser
Math. Comput. Appl. 2004, 9(3), 435-442; https://doi.org/10.3390/mca9030435 - 1 Dec 2004
Cited by 7 | Viewed by 1526
Abstract
In this work, the gas flow in the straight-through labyrinth seal is studied. Leakage flowrate and pressure distributions are calculated by using Neumann Modifed Method and circumferential velocity distributions are calculated by using Moody's Friction-Factor Model. Results are compared to the other papers. [...] Read more.
In this work, the gas flow in the straight-through labyrinth seal is studied. Leakage flowrate and pressure distributions are calculated by using Neumann Modifed Method and circumferential velocity distributions are calculated by using Moody's Friction-Factor Model. Results are compared to the other papers. Full article
1973 KiB  
Article
Modeling the Torque and Power Requirements of Traction Tires of Horticultural Tractors using Dimensional Analysis
by Sefa Tarhan and Kazim Çarman
Math. Comput. Appl. 2004, 9(3), 427-434; https://doi.org/10.3390/mca9030427 - 1 Dec 2004
Cited by 5 | Viewed by 1165
Abstract
The development of computational tools will promote the design and use of more energy-efficient tires. Two mathematical equations were developed by dimensional analysis to predict the torque and power requirements at zero net traction for traction fires (6.5-12; 7.00-18) on a hard surface. [...] Read more.
The development of computational tools will promote the design and use of more energy-efficient tires. Two mathematical equations were developed by dimensional analysis to predict the torque and power requirements at zero net traction for traction fires (6.5-12; 7.00-18) on a hard surface. Some structural and working parameters of fire that affect the torque requirement, such as tire size, tire deflection, tire load, and rolling radius, were considered for the analysis. Experiments were conducted to study the effect of different wheel sizes and system parameters on torque and energy consumed per unit distance traveled in a soil bin. The ratio of tire width over fire diameter and the ratio of tire deflection over tire section height were found to be dimensionless terms radically controlling the torque and energy requirements of tires. The prediction equation closely followed the experimental results. Full article
2436 KiB  
Article
Freeness Conditions of Tensors and Coproducts of Groups
by Ali Mutlu
Math. Comput. Appl. 2004, 9(3), 417-426; https://doi.org/10.3390/mca9030417 - 1 Dec 2004
Cited by 1 | Viewed by 1040
Abstract
Using a free simphicial group with given a CW-basis, we give an alternative description of the top group of the free square complex and 2-crossed complex of groups on 2-construction data in terms of tensors and coproducts of crossed module of groups. Therefore [...] Read more.
Using a free simphicial group with given a CW-basis, we give an alternative description of the top group of the free square complex and 2-crossed complex of groups on 2-construction data in terms of tensors and coproducts of crossed module of groups. Therefore the functors are given between these categorical constructions. Full article
1422 KiB  
Article
On the Kr-Core of Complex Sequences and the Absolute Equivalence of Summability Matrices
by Celal Çakan and Cafer Aydin
Math. Comput. Appl. 2004, 9(3), 409-416; https://doi.org/10.3390/mca9030409 - 1 Dec 2004
Viewed by 1042
Abstract
The Kr-core of a complex valued sequence has been introduced in [5]. In this paper, we have determined a class of matrices such that Kr - core (Ax) ⊆ Kr - core (x) hold for all x ∈ L [...] Read more.
The Kr-core of a complex valued sequence has been introduced in [5]. In this paper, we have determined a class of matrices such that Kr - core (Ax) ⊆ Kr - core (x) hold for all x ∈ L. Also; we have defined a new type of absolute equivalence, r - absolute equivalence, and characterized these type of matrices. Full article
2289 KiB  
Article
Determination of Friction Coefficient at Journal Bearings by Experimental and by Means of Artificial Neural Networks Method
by Bekir Sadik Ünlü, Hülya (Kaçar) Durmuş, Cevdet Meriç and Enver Atik
Math. Comput. Appl. 2004, 9(3), 399-408; https://doi.org/10.3390/mca9030399 - 1 Dec 2004
Cited by 6 | Viewed by 1288
Abstract
Knowing friction coefficient is important for determination of wear loss conditions at journal bearings. Tribological events that influence wear and its variations affect experimental results. In this study, friction coefficient at CuSn10 Bronze radial bearings has been determined by a new approach as [...] Read more.
Knowing friction coefficient is important for determination of wear loss conditions at journal bearings. Tribological events that influence wear and its variations affect experimental results. In this study, friction coefficient at CuSn10 Bronze radial bearings has been determined by a new approach as experimental and artificial neural networks method. In experiments, effects of bearings have been examined at dry and lubricated conditions and at different loads and velocities. Full article
1265 KiB  
Article
On the Properties of (k+1)-Dimensional Time-Like Ruled Surfaces with the Space like Generating Space in the Minkowski Space IR1n
by S. Can, B. Uyar and İ. Aydemir
Math. Comput. Appl. 2004, 9(3), 393-398; https://doi.org/10.3390/mca9030393 - 1 Dec 2004
Viewed by 1127
Abstract
The purpose of this paper is to introduce a summary of known results and the definition of the time-like ruled surface with the space-like generating space in the Minkowski space IR1n, and to present some characteristic results related with minimality [...] Read more.
The purpose of this paper is to introduce a summary of known results and the definition of the time-like ruled surface with the space-like generating space in the Minkowski space IR1n, and to present some characteristic results related with minimality and total developability of the ruled surface in the n-dimensional Minkowski space IR1n. Full article
3179 KiB  
Article
A Cubic B-Spline Collocation Method for the EW Equation
by İdris Dağ and Bülient Saka
Math. Comput. Appl. 2004, 9(3), 381-392; https://doi.org/10.3390/mca9030381 - 1 Dec 2004
Cited by 33 | Viewed by 1646
Abstract
A numerical solution of the Equal Width (EW) equation based on a collocation method incorporated cubic B-splines is investigated. Accuracy of the proposed method is shown numerically by calculating conservation laws, L2 and L norms on studying migration of a single [...] Read more.
A numerical solution of the Equal Width (EW) equation based on a collocation method incorporated cubic B-splines is investigated. Accuracy of the proposed method is shown numerically by calculating conservation laws, L2 and L norms on studying migration of a single solitary wave. It is shown that the collocation scheme for solutions of the EW equation gives rise to smaller errors and is quite easy to implement. The development of the undular bore and generation of the waves are studied for the EW equation. The linearized stability of the proposed method is derived by using Von Neumann stability analysis. Full article
2100 KiB  
Article
Linear Forced In-Plane and Out-of Plane Vibrations of Frames Having a Curved Member
by H. A. Özyiğit, H. R. Öz and M. Tekelioğlu
Math. Comput. Appl. 2004, 9(3), 371-380; https://doi.org/10.3390/mca9030371 - 1 Dec 2004
Cited by 1 | Viewed by 1068
Abstract
The forced, in-plane and out-of-plane vibrations of frames comprised of straight and curved members are investigated using Finite Element Methods. The straight and curved beams are assumed as Euler-Bernoulli type and they have circular cross-sections. The frame lies in a single plane. In [...] Read more.
The forced, in-plane and out-of-plane vibrations of frames comprised of straight and curved members are investigated using Finite Element Methods. The straight and curved beams are assumed as Euler-Bernoulli type and they have circular cross-sections. The frame lies in a single plane. In the analysis, elongation, bending and rotary inertia effects are included. Four degrees of freedom for in-plane vibrations and three degrees of freedom for out-of-plane vibrations are assumed. The in-plane and out-of-plane point and transfer receptances are obtained in order to determine the sensitive and non-sensitive frequency interval of the frame system. Full article
3106 KiB  
Article
A Feature Based Parametric Design Program and Expert System for Design
by Hüdayim Başak and Mahmut Gülesin
Math. Comput. Appl. 2004, 9(3), 359-370; https://doi.org/10.3390/mca9030359 - 1 Dec 2004
Cited by 11 | Viewed by 1393
Abstract
In this study, a feature based parametric design program including manufacturing features which are used in machining of prismatic parts by chip removal methods has been developed. Prismatic parts modelled in the feature based system can be modified parametrically by the developed parametric [...] Read more.
In this study, a feature based parametric design program including manufacturing features which are used in machining of prismatic parts by chip removal methods has been developed. Prismatic parts modelled in the feature based system can be modified parametrically by the developed parametric design module. To modify the part model parametrically enables feature based modelling process to be flexible and easy In the developed program. the features which are added to the models prepared by a feature based design program are evaluated by the expert system module and They are used in part modelling after determining of their compatibilty according to the rules. The aim of this study is to model the manufacturing features such as a pocket, slot and hole that are used in machining operations by adding to prismatic parts, to enable the modification of the part model parametrically and to warn, inform and guide the user for design and manufacturing mistakes. The system has been developed in AutoCAD using AutoLISP language. Full article
2890 KiB  
Article
Solvability Conditions and Green Functional Concept for Local and Nonlocal Linear Problems for a Second Order Ordinary Differential Equation
by Seyidali S. Akhiev
Math. Comput. Appl. 2004, 9(3), 349-358; https://doi.org/10.3390/mca9030349 - 1 Dec 2004
Cited by 5 | Viewed by 1052
Abstract
A generally nonlocal problem is investigated for a class of second order differential equations with weak singularities. New adjoint problem and Green functional concepts are introduced for completely nonhomogeneous problem. The solvability conditions of the completely nonhomogeneous problem and corresponding adjoint problem are [...] Read more.
A generally nonlocal problem is investigated for a class of second order differential equations with weak singularities. New adjoint problem and Green functional concepts are introduced for completely nonhomogeneous problem. The solvability conditions of the completely nonhomogeneous problem and corresponding adjoint problem are obtained in an alternative form. Full article
4711 KiB  
Article
On the Mathematical Modeling of Beams Rotating about a Fixed Axis
by Sevda Telli and Osman Kopmaz
Math. Comput. Appl. 2004, 9(3), 333-347; https://doi.org/10.3390/mca9030333 - 1 Dec 2004
Cited by 5 | Viewed by 1150
Abstract
In this paper, the equations of motion of a rotating beam encountered in various mechanical systems are given in the Euler-Newtoian form using four different dynamic modelling approaches. These models differ from each other in that they use different elastic displacements to define [...] Read more.
In this paper, the equations of motion of a rotating beam encountered in various mechanical systems are given in the Euler-Newtoian form using four different dynamic modelling approaches. These models differ from each other in that they use different elastic displacements to define the state of deformed beam, i.e. the longitudinal and transversal deflections model, the axial and transversal deflections model, the axial, transversal deflections and slope angle model, and finally the transversal deflection with normal force model, which are abbreviatedly denoted by the UVM, the SVM, the SVφM, and the VNM. Following a brief discussion about geometric relationship among three linear elastic displacements,–that is, the longitudinal u-, the transversal ν-, and the axial s-displacements– geometric stiffening effect, and the choice of spatial functions consistent with boundary conditions to discretize equations of motion, simulation results found from these models are presented in graphics, and comparatively evaluated. It is concluded that the SVM and the SVφM is most reliable models provided that the comparison functions for axial displacement s are the eigenmodes of a fixed-free, longitudinally vibrating rod. The VNM appears to be a prudential model, because it always gives results above those obtained by the SVM. Full article
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