University of Thi-Qar Journal for Engineering Sciences

This paper proposes a controller design of a nonlinear model of an internal combustion engine based on linear quadratic regulator (LQR) technique.The design takes into consideration the effect of external disturbances that occurs during the operation of system. The equations of motion are linearized according to the perturbation theory in order to inspect the dynamic stability of the engine motion, and the subsequent design of appropriate feedback controllers for the system, which can be obtained by solving the LQR problem.The results show that the proposed controller has good performance and stability than PID controller.The simulations have been carried out in Matlab/Simulink environment.

The renewable or non-renewable modern energy kinds have many shapes to utilize power generation. The power chimney tower is one of them developed by low losses, simple and has high facilities that used in spilling oil and/or oil refinery stations and to save clean environment. In this paper, new base design of power chimney used to increase the utilized energy by increasing the number of burners in addition to introducing new burner design by adding directional vanes. Many parameters influencing the system operation were exactly studied to predict new operation phenomenon. This fundamentally depends the combustion of gases compound the spilled oil. Velocity distribution is the important parameter which gives the first prediction to put the position of erection of power turbine, made or not. The numerical analysis was presented by using GAMBIT and FLUENT 6.3 to predict the high velocity at the expansion of chimney near the Centre of burned gases cover collector. This position is very suitable for promoting and building the power turbine since the velocity was high when the compounded gases is combusted (that there components are the methane gas with other friendly gases and waste).Also, it is concluded that there are high temperature increased by using the new burner design reach (1400-1800) K in comparison with old design without swirlers. It is easy to erect steam or gaseous boiler in contact with furnace for utilizes the heat generated in electrical power generation.So, the other factors, temperature and pressure were studied to coincide with previous papers in this field. The validity of this study was done by comparison to same flow rate of air/fuel ratio of previous study findings to give similar results of parameters.

Hybrid electric vehicles (HEV) draw much attention during the last years due to the need for alternative power resources with reduced emissions. The major disadvantages of HEV are the heavy weight, high cost and complicated control strategies. This paper focuses on a developed design for electro-mechanical differential unit. Most designer uses differential block as a mechanical linkage between two power sources. In this paper the differential unit is modified to do more than linkage. It acts as a continuously-varying-transmission (CVT), electric motivation unit and power regeneration unit. This of course leads to more compact and light weight vehicles.The developed model uses three main units: Synchronous block, Differential block, and Induction block the three blocks are combined in a compact design. Mechanical-electrical power transformation is carried out through the synchronous block which acts also as regeneration unit during braking. On the other hand electrical-mechanical transformation is carried out through the induction unit. The differential unit plays the role of smart linkage between the synchronous and the induction units. Simulation through Matlab-simulink is carried to show the validity of the model. The developed model proved to satisfy the properties of CVT and driving demands torques.

Artificial neural networks (ANNs) are useful computing system which can be trained to learn complex relationship between two or more variables. It learns from examples and storage the knowledge for future use. In this study, a model for predicting the ultimate strength of circular concrete filled steel tube (CCFST) beam-columns under eccentric axial loads has been developed in ANN. The available experimental results for 181 specimens obtained from previous studies were used to build the proposed model. The predicted strengths obtained from the proposed ANN model were compared with the experimental values and current design provision for CCFST beam-columns (AISC and Eurocode4). Results showed that the predicted values by the proposed ANN model were very close to the experimental values and were more accurate than the AISC and Eurocode4 values. As a result, ANN provided an efficient alternative method in predicting the ultimate strength of CCFST beam-columns.

Columns are vertical compression members which carry primarily axial Compression load. The axial load may be associated with bending moments in one or two directions.Analysis of high strength concrete columns with circular cross section and spiral transverse reinforcement was presented in this paper.A computer program was used to do the analysis of high strength circular concrete columns. The variables considered in this article were concrete strength ranging from 55 MPa to 80MPa, volumetric ratios of steel used to confine the core concrete, amount of main reinforcement and axial load level. The results indicate that as increase in the amount of lateral steel, main steel, axial load and increase in concrete strength resulted in increases in strength capacity of column. The deformability of high-strength concrete columns can be improved significantly through confinement. The results obtained in this research are agreed with results obtained by experimental and analytical study conducted by other authors.

In this study, the dynamic analysis of non-prismatic simply-supported Euler-Bernoulli beam subjected to non-concentric compressive axial force has been presented. Kinetic and potential energy expressions of the model are derived. Hamilton‘s principle is used to obtain the governing equations of motion. The fourth order differential equation with variable coefficient of the beam dynamics and buckling is solved using Differential Transform Method (DTM) to obtain mode shape, natural frequencies and buckling load of the system. The computer package Mathematical is used to write a program to calculate the natural frequencies, buckling load and the mode shapes. The effects of the taper ratio, eccentricity, and bucking load are investigated. The results are compared with the results of the analytical solution where a very good agreement is observed. The results show that the natural frequencies of prismatic and non-prismatic beam decreased when the compressive axial force increased. Also, the results show that when the taper ratio and eccentricity increased, the natural frequency of non-prismatic increases. The buckling load factor decreases when the taper ratio increases.

Iraq climate is characterized by the temperature increase during most of the months. The ambient temperatures are considered the most important factor that effects the production, properties and durability of the concrete. This study aims to evaluate the effect of retempering concrete after 60 minutes from cast by three different methods (retempring by water, retempring by Superplasticizer(G51) and retempring by remixing)on some of the mechanical properties of High Strength Concrete (HSC).In this work, different tests methods are adopted such as compressive strength, splitting tensile strength, ultrasonic pulse velocity and a hammer rebound Schmidt tests. These tests are investigated at different ages (7, 14, 28, and 56 days). The results show the high strength concrete that retempered by superplasticizer ) G51 leads to higher strengths, higher Ultrasonic Pulse Velocity (UPV) and higher hammer rebound than direct cast. The rate of increase in the mechanical properties of the high strength concrete that retempered by G51 relative to direct cast concrete at age 56 days were 28.29% ,16.37%, 2.76%,and 16.02% for compressive strength, splitting strength, Ultrasonic Pulse Velocity (U.P.V.) and hammer rebound respectively.While the concrete that retempered by water leads to lower strengths , lower Ultra Sonic Pulse Velocity (UPV) and lower hammer rebound than the other mixes.For the High Strength Concrete (HSC) mixes, the compressive strength and splitting tensile strength are closely related to UPV with a high correlation coefficient, R2.

A numerical method is presented to investigate the turbulent free convection inside an enclosure with partitions. The conductive partitions were located at the bottom wall. The Navier-Stokes and energy equations besides to the kinetic and dissipation equations were discretized by using a finite volume method. The solution of these equations was made via constructing a Fortran 90 computer program. The turbulence in the flow was modeled by using a k-ε model. The obtained results show that the conductive partitions represented a key factor for enhancing the rate of heat transfer. Also the results showed that the partitions height has more effect on enhancing the rate of heat transfer compared with the partitions thickness.The height of partitions were ranged from 0.25≤ h ≤ 0.65 and the width from 0.07 ≤ w ≤ 0.13. The enclosure was partially heated and the range of the considered values of Rayleigh number was up to 1014. The maximum rate of heat transfer is enhanced by 35% with increasing partitions height up to h= 0.65.

The aim of this work is to recognize the bonding by flash welding of high conductor wire(2mm) which produced in UR Company of Nasseryah. The butt welding joint of this wire was completed with mixed dendritic structure including some defects (cracks and porosity). The hardness of the region is high the base structure due to existing copper oxide phase. When Filler metal alloy (silver-copper alloy) type BAg2 is used during welding the welding zone will contain three types of bonding phases, one of these phases will decrease the hardness of the structure in comparing with the base. The all structure was defect free.