Journal of Techniques

The study of the effects of different kinds of fuel on the efficiency of steam boiler was carried out in order to improve the combustion process of boiler by study of some operation variables, combustion effect , mixing percent of the air and fuel on the boiler efficiency. It is observed that the air/fuel ratio has a main controller on the combustion process. Wherein the best performance for the combustion about( ),So the best combustion process about ( ), It was found that the best excess air is (5-10%).It is one of the important factors affecting combustion process and boiler efficiency. The employment of excess air to reduces efficiency of the boiler and causes rejection of great amounts of hot flue gases. It is observed that the use of (20%) excess air more than theoretical necessary air for fuel combustion reduces the efficiency about (1-4.5%).As the reduction of boiler efficiency at small amount of air entering to a furnace comes back to combustion because of necessary air lack. It was also found that the value of reduction is more than excess air for this case. It was about (10-50%) of boiler efficiency. On the other hand, another operation variable has secondary effect on the combustion process and boiler efficiency. Also the kind of fuel has impression on the fuel contents such as high hydrogen percent converted to vapor which produced in flue gases that causes energy loss and efficiency reduction.

It is a practical study that is experimental on horizontal cylinder which is put without a stream and in front of it; two plates are placed as directors for the trend of rising air according to the difference of intensity.
As it is steady by the results, the existence of these plates makes the process of heat transition is increased more according to the orientation of air towards the sylinder and this is related to the increase in the heat exchange between the air and the cylinder that is heated by fixed heat inundation of a result to the control on the growth of the contiguous layer that is regarded as negative factor in the process of heat transition. And it has been reached that, approximately the best angle for the directors of air trend is (θ=45) and the best position is (y/d=1.5).

In this research, the rotary regenerator is analyzed by solving government differential equations of heat transfer in the regenerator analytically and comparing the results with the designed data in order to study the performance of the rotary regenerator. In solving these equations, several assumptions have been considered; the most important are the constant temperature for both fluids at the inlet and the unchangeability of mass flow for each with the negligible of longitudinal heat transfer in flow direction. The results have shown good approach to the designed data. The percentage of error of the temperature of air combustion is (3%) and for flue gas temperature (4%). So, it can be said that this model can be used for studying the effective parameters on the work of the regenerator in order to reach the best performance of the regenerat

This work studies the operation of controlling the separation of flow (delaying the separation) on a cambered unsymmetrical surface which leads to improving the lift coefficient by using internal excitation technique, for a range of frequency at a constant density level (80 dB) with changing its position.
The experimental study was made on two locally –manufactured unsymmetrical wood models of airfoil type (NACA 23015). The position of the excitation first one is (11.5% chord) from the leading edge, while the second one’s is (6% chord) from the leading edge. The dimension of the airfoil is (150 mm) chord length and (305mm) length.
The experiments were made at a frequency range (50 ,100,150,200,250,300,350,400) Hz, and the angles of attack were (3ο,6ο,9ο,12ο), in an open subsonic wind tunnel for (Re.=3.3 x105) with using internal sound excitation production devices, excitation circuit (frequency generator, power amplifier, excitation sources).
The tests showed the effect of internal acoustic excitation frequency value and changing its position on the aerodynamic coefficients.
The aerodynamic coefficient was improved at frequency value (150Hz) for all the angles of attack, this is because this frequency is close from the frequency of cavity resonance at which the shear layer stress frequency equals the acoustic excitation frequency which leads to converting the laminar flow to turbulence flow .The improvement rate becomes clear at an angle of attack (12ο), it was noticed also that changing the position of the internal acoustic excitation on the outer surface of the profile to be near from the leading edge increases the lift coefficient. The increase rate becomes (28.5%) in lift coefficient for the slot position (6% chord) from the leading edge which is higher than the slot position (11.5% chord) from the leading edge for an angel of attack (12ο).

Previous researchers were concentrated on finding the coefficient of transmissibility of river gravels. While, in this research quarried rocks, monosized and gradated, was used to determine the coefficient of transmissibility.
In this research, four samples of quarried rocks were steadied. Tow of them monosized rock with diameters (-50.8+38.1), (-25.4+19.1) mm and other two gradations of mean particle diameter i.e. (35,33) mm were used to determine the coefficient of transmissibility of quarried rocks.
It was found that the range of coefficient of transmissibility lies between (14.5-53) cm/sec.

Kerbala City has faced by rapid urban growth during last years as a result of several factors.
This urban growth has led to the fact that the old inherited urban fabric has destroyed .
The city centre was severely damaged Almaarik during the –Um-Almaark battle. The town planning and development directorate
( ministry of domestic Affair ) prepared a project for Kerbala city which aims toward the reconstruction of the area demolished by the war , especially those located between the two holy shrines of Imam Hussain and Imam Abbas , according to the modern criteria in town planning.

The Aim of the study :

• The study of the marketplaces before the proposed project .
• Evaluation of marketplaces if the project is realized .
• Recommendations and suggestions of for the management of the probable problems after carrying out the project .

Samples of Nix Zn1- xFe2O4 (Nickel – Zinc) ferrite were prepared in ceramic preparation method in the tech. university and Almelaad company laboratories , because of their suitability to use in RAM ( radar absorbing materials ) preparation , the final sample of 3.2 mm thickness , x= 0.1 ,very high purity raw materials (99.99%) and sintering at 1350 C was the best to absorb x-band microwave radiation which extend from 8to12 GHz .

In this paper the laser beam (Ne-He type) with wavelength (0.6328 mm) is used to measure laminar flame speed for Methane-Air pre-mixture by limit the flame position in the combustion chamber. This is achieved by cutting the laser beam the flame perpendicularly at certain distances and calculate the time that take of flame to cross the certain distances.
All measurements were done at pre-pressure period .A density ratio method was employed to obtain the laminar burning velocity. Comparison the results with other published results indicate a reliable technique that is used in the present work

This paper presents a brief description of Lyapunov's direct method, and demonstrates its efficiency with respect to previous indirect step by step method, in order to compute the stability of electromechanically power system. The practical advantages of this direct method of analysis are:
(i) Rapid solution.
(ii) Ability to compute the degree of stability.
(iii) For computing the critical clearing time integrate the faulted equation, until V=V1.
The basic concepts and the mathematical formulation of the method are summarized. Practical test system are used to demonstrate the superior efficiency of the method relative to step by step method.

There aren,t a lot of studies in a hot asphaltic concrete mixture field that depends on test process results on Marshall Method and determing the combination between the Marshall main properties such as (Stability , Bulk density , voids ratio percent , Flow and voids percent filled with bitumen) .
The research depends on the bitumen percent of (4% , 4.5% , 5% , 5.5% and 6%) to determine the optimum bitumen content for Marshall test by using row materials purches to “ Daurah Asphalt Plant “ in project office of Amant Baghdad using grade of asphalt cement (40 – 50) penetration obtained from the Daurah Refinery “ .
Through the formulas application the optimum bitumenouse content (O.B.C) which appear (5.16%) . Samples of asphaltic concrete with the (O.B.C) were tested then get results meet requirement of “ Specification for Roads and Bridges “ S.O.R.B – 1999 .
Bitumen percent ratio should be not used in asphaltic concrete mix design with 4% and les 6% and up due to bad results and not fit the (S.O.R.B) specification in voids ratio percent ,voids ratio filled with bitumen for the first percentage and stability , flow , voids ratio percent , voids ratio percent filled with bitumen for the second percentage respectively .
The results showed that the value of stability test in different degree of temperature increased with low of 60C0 as in 30C0 , 45C0 and it’s value decreased for the samples test up of 60C0 as in 70C0 test .

Kirkuk reduced crude oil was hydro-demetallized over two particle size (0.2 - 0.3 and 0.2 - 0.5 cm) Ni-Mo/γ-Al2O3 catalyst beds. The catalyst bed length varied from 12.7 to 31.8 cm and the liquid hourly space velocity varied from 0.5 to 4.2 h-1. Reaction temperature was kept constant at 360oC. Also, hydrogen pressure and hydrogen to reduced crude oil ratio were kept at 3.2 Mpa and 400 cm3 cm-3. The effects of catalyst particle size, catalyst bed porosity, catalyst bed length and superficial liquid reduced crude oil flow through trickle-bed reactor has been studied. The results show, that apparent rate constant increased with increasing liquid velocity and bed length while decreasing in apparent rate constant with increasing of bed porosity and particle size of the catalyst.
Two empirical hydrodynamic models described the behavior of apparent rate constant of the hydro-demetallization has been discussed. First, the classical empirical hydrodynamic model proposed by Garcia and Pazos [1]. Second, suggested model denoted as Reynolds empirical hydrodynamic model. Statistical analyses of these two models show that both models represented well the effect of particle size, bed length, bed porosity and liquid superficial velocity on the apparent rate constant of the hydro-demetallization reaction. But suggested Reynolds hydrodynamic model, was more accurate than classical hydrodynamic model.

In the present work a numerical analysis of the time required for saturation of an earth dam is investigated using variably saturated flow model. The sensitivity analysis to the soil properties such as hydraulic conductivity, soil retention parameters (n and ), drainable porosity and initial pressure head are studied for different degree of hydraulic anisotropy. The progress of saturation is observed and inflow and outflow rates are computed for assigned times and then employed to indicate the time required for saturation (TS) of earth dam. The results are compared with the available analytical solution which ignored most of the soil properties. The results for different values of degree of hydraulic anisotropy indicate that the hydraulic conductivity, soil retention parameters, drainable porosity and initial pressure head have significant effect on TS. On the other hand, the results indicate that TS increases considerably with an increase in the degree of hydraulic anisotropy

The work presented in this paper is concerned with design an optimized structure of a digital Proportional – Integral – Derivative (PID) controller to be implemented using Field Programmable Gate Array (FPGA).
The analog PID controller was firstly considered to control a 3rd order plant, the optimum parameters of this controller is estimated using signal constraint block provided with Simulink. The discrete time PID controller is developed from analog counterpart using trapezoidal integration to approximate integral action and a backward difference for derivative action. From the time response point of view, simulation result shows that the discrete time controller has the same characteristics of the analog controller.
The digital prototype of the discrete time PID controller was performed using Very high speed integrated circuit Hardware Description Language (VHDL) in order to implement based on FPGA. Results show the improvement of control system from the processing time and design flexibility points of view

In this paper a new simulation tool is described, which enables direct animation and visualization of single-phase capacitor motor operation. The method used finite element results of magnetic vector potential and magnetic flux density vector to create animation file which displays the events inside the motor at different conditions. The implementation is by software package (ANSYS V.8). The main purpose of this tool is to give the students a clear understanding of the operation of motor, and to create the consecutive images that one needs to produce to give the students the necessary visual effect.

The current source inverter-fed induction motor drive (hereafter referred to as CSIM drive) is one of widely used drives in the industry. Of the many strategies employed for the control of CSIM drive, angle control is the simplest scheme incorporate the aspect of "frequency compensation", thus paving the way for a fast response CSIM drive.
A step by step design of the angle-controlled CSIM drive is described.A systematic design of inner current loop, slip speed loop, outer speed loop, and frequency compensation loop is given. The design incorporates a linear relationship between the reference input and output of electromagnetic torque and strategy to obtain maximum torque per ampere. The commutation delay in the current source inverter is taken care of in the design of the frequency compensator.
Experimental results are given in support of the design procedure

The aim of present paper to show the linear relation between noise and vibration amplitudes with different phase time shift in oblique – cutting. The level of stability is increased as the depth of cut to is decreased because the ratio (to / so) reduces the values of the dynamic chip thickness coefficients in oblique – cutting.
The diagnosis and reductions of the vibration and noise in oblique- cutting were made to show firstly the effect of rotational speed and depth of cut changes on the calculated stability chart, secondly the calculated stability chart of vibration which is based on the complicated theory can

The suitable experimental methods were used for measuring the mass, damping factor, damping coefficient and natural frequencies in both oblique and in orthogonal cutting. The stiffness of the headstock and tailstock are considered in the evaluation of the vibrational properties of the workpiece with grooves in oblique-cutting. The theoretical investigation was made also to calculate the stiffness and the damping coefficients in two axis directions included suitable and required mathematical method on the tested model in orthogonal- cutting

The basic items of this research include presentation of the contents of the (Auto-cad) system the design, with the help of CAD computer". The research has tacked the concept of cad-system, its advantages applications, typical use requirements of design using computer Advantages are: in furniture industry, savings made as a result of computer use, on theoretical level practically the project has dealt with the process of fitting the pieces of furniture together. After several attempts, a new way of fitting parts together has been concluded which has achieved planty of savings in the shown tables within the research

The corrosion inhibitor” OLAZOL T2P” belongs to the class of nitrogen-containing cationic surface-active substances and is design for anticorrosive treatment of pipelines and equipment used in oil and gas industry.
The protective effect of olazol T2P phase film in the water-oil emulsions reaches 85-95% olazol T2P prevents from corrosion cracking and suppresses the growth of sulfate-reducing bacteria.

An incompressible fluid flow and heat transfer by natural convection inside a rectangular cavity had been studied numerically. The study focused on the variation of velocity vectors and temperature values due to the change of Grashof number and an enclosure aspect ratio. The Grashof numbers was ranging from 103 to 105. Nusselt number dependence on temperature field especially near hot and cold walls is verified. The continuity, momentum and energy equations have been solved using finite volume method (FVM). The results show that the central core region is distorted with increase of Grashof number. Also the results indicated that the rate of heat transfer is increased with the increase of Grashof number. The validation of the computed results is verified through the comparison with the published results.

This paper presents a random number generator, for use in generating cryptographic keystreams, based on the division algorithm. This generator permits choice of seed values giving a long cycle length that is known a priori and costlessly decimal keystream periodicity. The keystream can be used in Stream Cipher System.

This research aim to study the effect of adding alumina and graphite particles on the mechanical and tribological properties of composite material based on an epoxy resins. The epoxy matrix was reinforced with (10-40) (wt %) of alumina particles to improve its mechanical and tribological properties.
Measurement of density, friction compressive strength and hardness revealed that the properties of the prepared composite were enhanced by the addition of the alumina particles. These improvements in the physical and mechanical properties lead to decrease the coefficient of friction, which is the tribological property we were aiming to decrease. (20%) alumina was found the best.
In order to enhance the friction property of the composite, some (wt %) of graphite powder was added to 20wt % alumina-epoxy composite. In fact this was the case; the coefficient of friction was decrease further more, and also the other physical and mechanical properties except hardness (which is considered as a surface property) giving a possibility of using the prepared composite in many different applications.

The dispersion stability was examined for alumina particles in solutions of different alkyl methacrylates (methyl, n-butyl and 2-ethylhexyl)/methacrylic acid copolymers. It was found that good dispersion can be obtained from solutions of n-butyl methacrylate/methacrylic acid and 2-ethylhexyl methacrylate / methacrylic acid copolymers and that they settled as good deflocculated suspensions, whereas aggregation was much easier using methyl methacrylate/methacrylic acid copolymers.
Sedimentation test was used to determine the dispersion quality, which involved measuring the sediment volume of the packed alumina after gravity settling. The influence of dispersion media and copolymer structure was also studied.

Pseudorhipidionina tubaensis , new foraminifera from the Late Cenomanian of Mishrif formation (Tuba region, W Basrah) is described and figured . The paleoenvironment of the Pseudorhipidionina is concluded as shallow sublittoral marine restricted environment according to the lithological features and faunal association

At the present time, a considerable amount of works has been undertaken to investigate the mechanical properties of lightweight aggregate concrete. It is thus aimed in this work to investigate the possibility of using local pumice rocks (available in the north of Iraq ) for the production of structural lightweight aggregate concrete.
In this investigation, two types of lightweight concrete ( LWC) were produced using pumice stone as a coarse aggregate with natural sand and also with fine pumice aggregate, the effect of incorporating high range water reducing admixture (HRWRA) synergistically with 8% rice husk ash (RHA), as a partial replacement by weight of cement, on the mechanical properties of LWAC were investigated.
Hardened unit weight, compressive strength and splitting tensile strength were investigated for all types of lightweight aggregate concrete and at various ages of curing.
The inclusion of 8% RHA, as a partial replacement by weight of cement, with the optimum dosage of HRWRA ( 6% by weight of cement ) showed considerable increase in mechanical properties at all ages of curing compared with the reference concrete.Key words : lightweight concrete , pumice , admixture , lightweight aggregate concrete .

This paper describes an experimental investigation on the compressive strength and swelling properties of clay reinforced with metal fiber.
Different percentages of fibers mixed with soil were used to prepare specimens to be tested. The result of this study showed that both peak strength and strain at failure increased with increasing fiber content while swelling pressure and swelling potential decreased with the increase of fiber content. The suitable fiber content was found to be 8%.