Issue 4

JTAM, Sofia, vol. 42 Issue 4 (2012)

A Computer Program for Drip Irrigation System Design for Small Plots

Nina Philipova1, Olga Nicheva2, Valentin Kazandjiev2, Mila Chilikova-Lubomirova2
1Institute of Mechanics, the Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 4, 1113 Sofia, Bulgaria
2National Institute of Meteorology and Hydrology, Tsarigradsko Blvd 66, 1784 Sofia, Bulgaria

A computer program has been developed for design of surface drip irrigation system. It could be applied for calculation of small scale fields with an area up to 10 ha. The program includes two main parts: crop water requirements and hydraulic calculations of the system. It has been developed in Graphical User Interface in MATLAB and gives opportunity for selecting some parameters from tables such as: agro-physical soil properties, characteristics of the corresponding crop, climatic data. It allows the user of the program to assume and set a definite value, for example the emitter discharge, plot parameters and etc. Eight cases of system layout according to the water source layout and the number of plots of the system operation are laid into hydraulic section of the program. It includes the design of lateral, manifold, main line and pump calculations. The program has been compiled to work in Windows.

JTAM, Sofia, vol. 42 Issue 4 pp. 03-18 (2012), [Full Article]

Buckling of Beams and Columns under Combined Axial and Horizontal Loading with Various Axial Loading Application Locations

Amir Javidinejad
Zodiac Aerospace 7330 Lincoln Way Garden Grove, CA USA

In this paper the buckling behaviour of an I-beam under combined axial and horizontal side loading is examined. It is to shown that the actual application location of the axial loading governs the buckling behaviour of the long I-beam. Theoretical formulation is developed to determine the critical buckling load for such combined loading configuration from the elastic static theory. Both, the beam deflection theoretical model and the critical load capacity are derived for this combined loading condition. The Finite Element Analysis (FEA) is utilized to apply the axial load on the beam at various configuration locations and it is shown that this application location determines the buckling behaviour and the critical load of the buckling of the I-beam. Numerical example is given.

JTAM, Sofia, vol. 42 Issue 4 pp. 19-30 (2012), [Full Article]

Vibration Effects Examination of Cushions Used on Tractor Driving Seat

Musa Marul1, Abdurrahman Karabulut2
1Artvin Çoruh University, Hopa Vocational High School Mechatronics Program, Artvin, Turkey
2Afyon Kocatepe University Technology Faculty Mechanical Engineering. Afyonkarahisar, Turkey

Vibration effect of driver’s seat of agricultural tractor which works in land condition has been researched. In this research, three different cushions on driver’s seat have been used. These are wool, sponge and cotton. Pad acceleration receiver is put on seat. Moreover, HVM100 tool has been used to record data. Data has been converted to graphs in BLAZE software. Statistical methods have been used in examining the graphs. In vibration isolation, ordering has been achieved as wool, cotton and sponge and without a cushion, respectively. Wool cushion has the best isolation. It is seen that data obtained from test results is appropriate according to ISO 2631 standards and scientific researches.

JTAM, Sofia, vol. 42 Issue 4 pp. 31-40 (2012), [Full Article]

Analysis of Mixed Mode II/III Crack in Bilayered Composite Beam

Angel S. Mladensky, Victor I. Rizov
University of Architecture, Civil Engineering and Geodesy, 1, Chr. Smirnensky Blvd., 1046 Sofia, Bulgaria

Mixed mode II/III crack investigation in cantilever bilayered unidirectional fiber reinforced composite beam is reported. The crack is situated between the layers. The two crack arms have different widths. Formula for the strain energy release rate is obtained by the linear elastic fracture mechanics methods using the magnitude of the applied forces, geometrical characteristics of the cross-section, and the elastic moduli of the layers. An equivalent shear modulus of the un-cracked beam portion is used. Several diagrams illustrating the results of parametrical analysis of the strain energy release rate are presented. The paper is a part of a research in the field of fracture behaviour of composite beams.

JTAM, Sofia, vol. 42 Issue 4 pp. 41-52 (2012), [Full Article]

Convection Heat and Mass Transfer in a Power Law Fluid with Non-Constant Relaxation Time Past a Vertical Porous Plate in the Presence of Thermo and Thermal Diffusion

B. I. Olajuwon, I. S. Oyelakin
Department of mathematics, University of Agriculture, Abeokuta, Nigeria

The paper investigates convection heat and mass transfer in power law fluid flow with non relaxation time past a vertical porous plate in presence of a chemical reaction, heat generation, thermo diffusion and thermal diffusion. The non – linear partial differential equations governing the flow are transformed into ordinary differential equations using the usual similarity method. The resulting similarity equations are solved numerically using Runge – Kutta shooting method. The results are presented as velocity, temperature and concentration profiles for pseudo plastic fluids and for different values of parameters governing the problem. The skin friction, heat transfer and mass transfer rates are presented numerically in tabular form. The results show that these parameters have significant effects on the flow, heat transfer and mass transfer.

JTAM, Sofia, vol. 42 Issue 4 pp. 53-74 (2012), [Full Article]

Raleigh Wave in a Rotating Magneto-Thermo-Elastic Half-Plane

Baljeet Singh1, Sangeeta Kumari2, Jagdish Singh
1Department of Mathematics , Post Graduate Government college, Sector 11, Chandigarh -160011, India
2Department of Mathematics , Maharishi Dayanand University, Rohtak- 124001 , Haryana, India

The governing equations of generalized magneto-thermoelasticity with hydrostatic initial stress and rotation are solved for surface wave solutions. The particular solutions are applied to the boundary conditions at a free surface of a half-space to obtain the frequency equation of Rayleigh wave. For numerical purpose, the frequency equation is approximated for small thermal coupling. The velocity of propagation and amplitude-attenuation factor of Rayleigh wave are computed numerically for a particular material. Effects of rotation, magnetic field, hydrostatic initial stress and relaxation time on the velocity of propagation and amplitude-attenuation factor are shown graphically.

JTAM, Sofia, vol. 42 Issue 4 pp. 75-92 (2012), [Full Article]