Print ISSN: 1813-162X

Online ISSN: 2312-7589

Volume 16, Issue 1

Volume 16, Issue 1, Winter 2009, Page 1-132


ANALYSIS OF COMPUTER AIDED PROCESS PLANNING TECHNIQUES

Dr. Salim A. Saleh

Tikrit Journal of Engineering Sciences, Volume 16, Issue 1, Pages 74-92

Computer Aided Process Planning ( CAPP) has been recognized as playing a key role in Computer Integrated Manufacturing ( CIM ). It was used as a bridge to link CAD with CAM systems, in order to give the possibility of full integration in agreement with computer engineering to introduce CIM. The benefits of CAPP in the real industrial environment are still to be achieved. Due to different manufacturing applications, many different CAPP systems have been developed. The development of CAPP techniques needs to a summarized classification and a descriptive analysis. This paper presents the most important and famous techniques for the available CAPP systems, which are based on the variant, generative or semi-generative methods, and a descriptive analysis of their application possibilities.KEYWORDS: CAPP, CIM, CAD/CAM, Machining.

KINETIC MODELS STUDY OF HYDRODESULPHURIZATION VACUUM DISTILLATE REACTION

Hiadar A. Areff; em A. Karim; Dr. Abdul Mun; Dr. Abdul Halim A. Mohammed

Tikrit Journal of Engineering Sciences, Volume 16, Issue 1, Pages 1-14

This study deals with kinetics of hydrodesulphurization (HDS) reaction of vacuum gas oil (611-833) K which was distillated from Kirkuk crude oil and which was obtained by blending the fractions, light vacuum gas oil (611 - 650) K, medium vacuum gas oil (650-690) K, heavy vacuum gas oil (690-727) K and very heavy vacuum gas oil (727-833) K. The vacuum gas oil was hydrotreated on a commercial cobalt-molybdenum alumina catalyst presulfied at specified conditions in a laboratory trickle bed reactor. The reaction temperature range (583-643) K,liquid hourly space velocity range (1.5-3.75) h-1 and hydrogen pressure was kept constant at 3.5 MPa with hydrogen to oil ratio about 250 lt/lt. The conversion results for desulphurization reaction appeared to obey the second order reaction. According to this model, the rate constants for desulphurization reaction were determined. Finally, the apparent activation energy (Ea), enthalpy of activation ( H*) and entropy ( S*) were calculated based on the values of rate constant (k2) and were equal 80.3792 KJ/mole, 75.2974 KJ/mole and 197.493 J/mole, respectively.KEY WORDS: Hydrodesulphurization reaction, Vacuum gas oil, Trickle bed reactor, Reaction kinetics models.

EFFECT OF SUCTION PIPE DIAMETER AND SUBMERGENCE RATIO ON AIR LIFT PUMPING RATE

Hayder A. AlAjawi; Dr. Salam J. AlMaliky

Tikrit Journal of Engineering Sciences, Volume 16, Issue 1, Pages 63-73

The increasingly importance for the uses of the air lift pump in widespread list of fields (mining, nuclear industries, agricultural uses, petroleum industries...etc.) makes it very interested for the researchers to find tools to raise the performance outcome of such pumps.An air lift pump system is setup to study the effect of the suction pipe diameter and submergence ratio on the liquid (water) pumping rate. The system has a lift pipe of (0.021 m) diameter and (1.25 m) length. Five diameters for the suction pipe (0.021, 0.027, 0.033, 0.048 and 0.063 m) with a fixed length of (0.3 m), are tested for each of the submergence ratios (0.2, 0.3, 0.4, 0.5) respectively. Results indicate that the higher the diameter of suction pipe is the higher the pumping rate for a fixed submergence ratio. From another side, the higher the submergence ratio is the higher the pumping rate for a fixed suction pipe diameter. Also, under high submergence ratios, high pumping rates are achieved by the use of lower air flow rates compared with those used with lower submergence ratios. The experimental results show good compatibility with the model suggested by Stenning and Martin for the performance of an air lift pump.KEYWORDS: Internal Heat Exchanger, R134a, vapor Compression Refrigeration Cycle.

CURING CONDITIONS INFLUENCE ON SOME ENGINEERING PROPERTIES OF LIME-TREATED EXPANSIVE CLAYEY SOIL FROM MOSUL AREA

Tikrit Journal of Engineering Sciences, Volume 16, Issue 1, Pages 1-15

يهدف البحث إلى دراسة تأثير تغير ظروف الإنضاج: وهما درجة الحرارة من10 ولغاية 60 درجة مئوية وفترة إنضاج تتراوح بين 2 و 90 يوم على بعض الخصائص الهندسية وخاصة النفاذية و مقاومة الانضغاط غير المحصور لتربة طينية انتفاخية معاملة بالجير المطفأ(النورة) بنسب (6,4,2)% لإحدى مناطق مدينة الموصل. أظهرت النتائج زيادة في مقاومة الانضغاط غير المحصور مع زيادة درجة الحرارة وخاصة في فترات الإنضاج القصيرة كما أحدث ارتفاع درجة حرارة الإنضاج زيادة في النفاذية بغض النظر عن نسبة الإضافة وذلك مقارنة بنفاذية التربة الطبيعية، لكنه اظهر تبايناً في قيمها مع اختلاف حرارة الإنضاج. من جانب اخر فان غسل التربة أدى الى انخفاض النفاذية في التربة المعاملة بغض النظر عن نسبة الإضافة ودرجة الحرارة لكن معدل انخفاض النفاذية في أثناء الغسل كان أسرع عند تعرضه للتأثير الحراري.الكلمات الدالة : التربة الطينية، النورة، تأثير ظروف الإنضاج، التوصيل المائي

PARAFFIN SEPARATION VACUUM DISTILLATIONCOLUMN ANALYSIS IN LINEAR ALKYL BENZENE (LAB)CHEMICAL PLANT USING CHEMCAD SIMULATOR

Omar S. Latif; Zaid A. Abdel-Rahman

Tikrit Journal of Engineering Sciences, Volume 16, Issue 1, Pages 15-30

Simulated column performance curves were constructed for existing paraffin separation vacuum distillation column in LAB plant (Arab Detergent Company/Baiji-Iraq). The variables considered in this study are the thermodynamic model option, top vacuum pressure, top and bottom temperatures, feed temperature, feed composition & reflux ratio. Also simulated columns profiles for the temperature, vapor & liquid flow rates composition were constructed. Four different thermodynamic model options (SRK, TSRK, PR, and ESSO) were used, affecting the results within 1-25% variation for the most cases. The simulated results show that about 2% to 8 % of paraffin (C10, C11, C12, & C13) present at the bottom stream which may cause a problem in the LAB plant. The major variations were noticed for the top temperature & the paraffin weight fractions at bottom section with top vacuum pressure. The bottom temperature above 240 oC is not recommended because the total bottom flow rate decreases sharply, where as the weight fraction of paraffins decrease slightly. The study gives evidence about a successful simulation with CHEMCADKEYWORDSProcess simulation, CHEMCAD Simulator, multicomponent distillation, LAB, paraffin column, vacuum pressure

NUMERICAL VALIDATION ON THE PERFORMANCE OF A TWO DIMENSIONAL CURVED DIFFUSER

Khalaf I. Hamada

Tikrit Journal of Engineering Sciences, Volume 16, Issue 1, Pages 105-120

This paper deals with the investigation of the characteristic of subsonic viscous flow through a curved diffuser numerically with commercial code for computational fluid dynamics (CFD) Fluent Inc. version 6.3. The diffuser flow is a two-dimensional, turbulent, incompressible and fully developed. The investigations are based on the Spalart-Allmaras turbulent model. A 2-D quadrilateral grid is generated by the grid generator GAMBIT. Obtainedresults are compared with the available experimental data and found to give good agreement. The effects of curvature angle, area ratio and adding tail channel with constant area on the diffuser performance and flow pattern are studied and revealed by the pressure contour, velocity vector, and variation of the pressure recovery factor for all above mentioned parameters.Key words: Diffuser performance, CFD, Turbulent flow

DCT/DPCM HYBRID CODING FOR INTERLACED IMAGE COMPRESSION

Khamies Khalaf Hasan; Amir; Dr. Saied Obied Abdul

Tikrit Journal of Engineering Sciences, Volume 16, Issue 1, Pages 121-132

By the nature of images, picture elements in local regions are highly correlated with one another. In such cases, image compression techniques are introduced to reduce the amount of data is needed to represent the same information, either exactly or approximately. In this work DCT/DPCM hybrid approach have been designed and implemented for interlaced images. The image signal was first transformed row-wise using discrete cosine transform (DCT) and a differential pulse code modulation (DPCM) scheme then was used column-wise to get difference signal. For still images the same 3-bit quantizer was employed which makes quantization process easier. For interlaced images 3-bit quantizer was used for the odd field and 2-bit quantizer for even field, since the difference signal of the even field was very small.A compression ratios of about 13:1 was obtained for interlaced image. Objective measurements showed a high peak to peak signal to noise ratio without noticeable impairment.KEY WORDS: Interlaced, Hybrid image compression, DCT/DPCM, Discarding

ANALYSIS OF THE HARMONIC ORDER AFFECTING THE EDDY CURRENT BRAKING FORCE IN ELECTRICALMACHINES

Amer M. Kado

Tikrit Journal of Engineering Sciences, Volume 16, Issue 1, Pages 93-104

This paper presents a computer analysis of the eddy current brake in electric machines. It presents a formula for the braking force when the actual width of the pole is considered. This formula is suitable for both thin and thick discs and may be employed for a wide range of working speed. For this purpose, a mathematical analysis of the problem is presented together with the formula achieved for the braking force. The brake is first represented by a mathematical model based on certain assumptions and then the braking force is obtained as a result of solving a field problem. The problem is simplified to a one-dimensional problem, where a solution for the magnetic vector potential is obtained, and by employing Lorentz force equation, a formula for the braking force of the nth harmonic order is obtained.KEYWORDS: Electric Machines, Eddy Currents, Braking Force, Electromagnetic Fields, Poisson’s equation.