Skip Navigation LinksVolume : Volume 9 No.1 2000

  
  
  
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the_effect_of_compaction_force_on_densification_behaviour_of_copper-tin_system.pdfTHE EFFECT OF COMPACTION FORCE ON DENSIFICATION BEHAVIOUR OF COPPER-TIN SYSTEM
  
ABSTRACT:

Copper~tin (Cu-Sn)  self-lubricating bearings have · been manufactured by powder metallurgy m.ethod. This paper describes the effect  of compaction force before sintering on the physical and mechanical properties of the  Cu-Sn system. The porosity, volume, hardness, transverse  rupture strength and fracture characteristics of the sintered specimen were analysed. It was observed that the porosity distribution within the sintered specimen was good at high compaction force. Therefore, it was revealed that the compaction fe>rce has a strong effect on the behaviour ar,d prop~rties of the Gu-Sn system.

AUTHOR:
Junaidah Jai, Syed Fadzil Syed Mohammad, Fauzi Ismail, Patthi Hussain and Azmi Idris
Year: 2000
surface_roughness_and_cavitation_effects_on.the_solution_of_thermohydrodynamic_bearings.pdfSURFACE ROUGHNESS AND CAVITATION EFFECTS ON THE SOLUTION OF THERMOHYDRODYNAMIC BEARINGS
  
ABSTRACT:

A thermohydrodynamic (THD) analysis of finite journal bearings witn rough surfaces and cavitation effect is presented. A modified two dimensional version of the Reynolds' equation which includes surface roughness effects is .solved using the successive-overrelaxation (SOR) method. The Swift-Stieber cavitation boundary condition was implemented in solving the Reynolds' equation. The variations of viscosity both across and along the film are considered. A so-called ISOADI boundary condition is used in solving the energy equation. When both bearing and journal  having the same roughness structure, a stiffer bearing stiffness and small temperature changes are obtained for isotropic roughness. The longitudinal roughness gives the maximum oil and.shaft temperature changes, the lowest leakage and the highest hydrodynamic load. Totally opposite results were obtained for transverse roughness. At the highest degree of surface roughness, the rough moving case produced the highest side leakage and lowest temprature. Meanwhile, the smooth moving case gives the lowest leakage and the highest oil-film temperature. The results obtained in the study have a good agreement with the published experimental works.

AUTHOR:
Che Hassan Che Haron
Year: 2000
strength_variability_in_3_mol_y-tzp_ceramics.pdfSTRENGTH VARIABILITY IN 3 MOL% Y-TZP CERAMICS
  
ABSTRACT:

Yttria-Tetragonal Zirconia Polycrystals (Y-TZP) ceramics have received great attention for structural applications mainly due to the high strength possessed by.the ceramic. In this work, the distribution curve of the bending strength of 3 mol% Y-TZP was analysed by Weibull analysis. In addition, the effect of external loading on the phase changes in the fracture surface was analysed using X-ray diffraction. Prepared samples were evaluated to determine the_phases present, bulk density, fracture toughness and hardness. Bending strength was measured from prepared bar samples by using three-point bend testing. The bending strength was found to vary between 621 MPa and 1100 MPa, yielding ari average value of 913 MPa. A Weibull modulus of 9.6 was obtained in this ceramic. Phase analysis of the fracture surface revealed high levels of monoclinic phase was present indicatiag that stress-induced tetragonal to monoclinic phase transformation as responsible for the high strength measured in this ceramic.

AUTHOR:
Ramesh Singh, C. Azlan and A. Che Husna
Year: 2000
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gas_holdup_in_gas-liquid_oscillatory_flow_in_a_baffled_tube.pdfGAS HOLDUP IN GAS-LIQUID OSCILLATORY FLOW IN A BAFFLED TUBE
  
ABSTRACT:

An experimental investigation of gas holdup in a gas-liquid oscillatory flow was carried out in  a baffled tube. The effects of gas flow rate, oscillation frequency, liquid flow rate and liquid viscosity on gas holdup were investigated. The gas holdup was found to increase with gas flow rate and oscillation rate, unaffected by liquid flow rate and decrease with liquid viscosity.

AUTHOR:
Mohd Sobri Takriff and Md. Zahangir Alam
Year: 2000
experimental_studies_of_the_convective_heattransfer_characteristics_in_compact_heat_exchanger_-.pdfEXPERIMENTAL STUDIES OF THE CONVECTIVE HEATTRANSFER CHARACTERISTICS IN COMPACT HEAT EXCHANGER
  
ABSTRACT:

An experimental study was carried out to investigate the convective heat transfer enhancement in compact heat exchanger by keeping pressure drop constant for a specific range. Three different types of configurations namely, staggered-symmetric (stager-sm), staggered-un symmetric (stager-us), and unstaggered (unstager) were used to find the optimum configuration i_n triangular ribbed test channel. The results were later  compared with a smooth channel. The investigation  was performed with both laminar and turbulent forced flows for Reynolds numbers ranging from 250 to 7000. The geometric parameters, in order to satisfy manufacturer demands, were fixed at pie 10 (ratio of rib spacing and rib height) and the wall temperature was held constant at 85 °C. The global measurement technique was used to determine the temperature distribution and pressure drop in the test duct. The results indicated that the staggered-symmetric configuration gives better results from the perspective of both the heat transfer and pressure drop. However, if the heat transfer rate is more important than pressure drop, then the staggered-un symmetric configuration can be considered.

AUTHOR:
Ibrahim Kilicaslan,  S. Kadri Yigit, Kamaruzzaman Soplan and Zafer Klzilkaya
Year: 2000
effect_of_rheology_on_gas_non-newtonian_liquid_flow_0.pdfEFFECT OF RHEOLOGY ON GAS NON-NEWTONIAN LIQUID ·FLOW
  
ABSTRACT:

Modifications on three currently available correlations were implemented to fit them to two-phase gas/non-N~wtonian liquid flow. The main modificaUons consist of changing the viscosity and the friction factor formulas. An experimental database has been developed for the evaluation of the modified correlations: Five hundred and eighty nine runs of steady state air/non Newtonian liquid upward flow were conducted; The test facility was an indoor 1.08 inch inside diameter, 0.00554 relative roughness pipe with a test section of 17.4 ft inclined . at four inclination angles (+5, + 10, + 15 & +20 degrees from the horizontal). The air was used as the gas phase while four fresh water muds (with different physical and rheological properties) were used as the non-Newtonian liquid. The experimental program was set up in a wide range of experimental conditions to cover the range of the inclination angles and the properties of the liquids; The evaluation of the modified correlations were carried out for all of the inclination angles. The flow  patterns, which formed at three  inclination  angles, were detected by superimposing our experimental data on the pre-prepared flow pattern maps. Statistical analyses were performed to indicate the best rheological model, which would represent the non~Newtonian liquid. It was also used in the evaluation of modified correlations. Beggs and Brill (1973) and Mukherjee and Brill (1985) correlations show satisfactory statistical results when compared between the measured and calculated pressure drops and liquid hold-up.

AUTHOR:
Amir T. AI-Wazzan
Year: 2000
an_object-oriented_expert_system_for_analysing_voltage_disturbances.pdfAN OBJECT-ORIENTED EXPERT SYSTEM FOR ANALYSING VOLTAGE DISTURBANCES
  
ABSTRACT:

Voltage disturbance has been the source of failure or misoperation of end user electronic loads. Therefore it is important to understand the cause of voltage related power quality problems and finding its solutions. This paper presents the development of an expert system for analysing voltage disturbances as an effort to understand power quality problems encountered in  distribution system. The expert system is designed based on the object-oriented concept,and it is implemented by using the expert system shell Kappa-PC. The system analyses a voltage disturbance by clarifying the disturbance symptom and the equipment used, identifying the type of disturbance, determining its causes and providing solutions to the problem. The system can be a useful tool for analysing voltage related power quality problem.

AUTHOR:
Azah Mohamed, Azmizi Mukhlis Hassan and Mohd Yusof Jamaluddin
Year: 2000