- TITLE:
MATHEMATICAL MODEL FOR A PNEUMATIC FORCE ACTUATOR SYSTEM
- AUTHOR(S):
A. Andreev, H. Hristov, G. Iliev, M. Racheva
- ABSTRACT:
We consider pneumatic cylinder tubes that connect valves with actuators. The aim of this work is to obiaun a new mathematical model for online control applications. For that purpose, a second-order hyperbolic equation corresponding to the model problem is derived. The Laplace transform is used and by this approach a sufficiently simple and applicable model is derived. The effect of different mathematical models for the considered problem is also discussed. Finally, some validation experiments by real engineering parameters are presented.
- TITLE:
MODELLING, RESEARCH AND OPTIMIZATION OF CARBIDIC AUSTEMPERED DUCTILE IRON DURING ABRASION AND DRY FRICTION
- AUTHOR(S):
V. Todorov, G. V. Duncheva, M. Atanasova, G. Rashev
- ABSTRACT:
This article presents the outcomes from experimental investigation of the wear resistance of specimens made of carbidic austempered ductile iron (CADI) which are isothermally hardened in the fields of upper and lower bainite. The specimens are subjected of abrasive wear and dry friction. A mathematical modeling of the experimental results has been carried out. A regression analysis and analysis of variance (ANOVA) have been fulfiled using QStatLab package. On the basic of the regression models obtained, three single-purpose optimization tasks have been solved in order to determined the maximum wear resistance of CADI.
- TITLE:
MODELLING, RESEARCH AND OPTIMIZATION OF MECHANICAL PROPERTIES OF CARBIDIC AUSTEMPERED DUCTILE IRON
- AUTHOR(S):
G. V. Duncheva, V. Todorov, M. Atanasova, G. Rashev
- ABSTRACT:
An object of this study is the effect of the carbide phase quantity and austempering temperature on the mechanical properties of samples made of carbidic austempered ductile iron (CADI). Analysis of variance and regression analysis have been carried out on the basis of experimental data obtained. On the basis of regression models obtained, three multi- objective optimization tasks have been set out solved.
Thus, the optimal values of liquid carbide phase and austempering temperature of CADI have been established.
- TITLE:
PERFORMANCE EVALUATION OF WIRE COIL INSERTS IN TURBULENT TUBE FLOW – CRITICAL REVIEW
- AUTHOR(S):
P. Bonev, V. M. Petkov
- ABSTRACT:
There are different kinds of inserts employed in the heat exchanger tubes such as helical/twisted tapes, coil wires, ribs/fins/baffles, and winglets. This paper presents performance evaluation of some wire coil inserts, using a simple evaluation criterion to assess the possible energy benefit. Wire coil inserts, classical and modified, with different geometrical parameters in the ranges: / 0.06 0.12e D , / 1.8 33.0p e , with working fluids as air or water in the range 5 Re (0.4 1.2) 10 have been taken into consideration.
- TITLE:
BALANCING THE INERTIA FORCES OF SINGLE CYLINDER HYPOCYCLOIDAL RECIPROCATING MACHINES
- AUTHOR(S):
V. Enchev
- ABSTRACT:
The purpose of this article is to determine the inertia forces of reciprocating moving masses of single cylinder hypocycloidal reciprocating machines and to present opportunities for their balance. Balancing of the rotating masses in the mechanism is possible by known methods with counterweights. Unbalanced inertia force of reciprocating moving masses of the piston and the point mass of the rod remains. This force can’t be ignored in high-speed compressors. On the other hand it is significant difficulty to balance this force and
requires deeper study to find ways to eliminate or limit its impact.
