E-ISSN: 2587-0351 | ISSN: 1300-2694
Pamukkale University Journal of Engineering Sciences - Pamukkale Univ Muh Bilim Derg: 3 (3)
Volume: 3  Issue: 3 - 1997
1. Cover-Contents
Pamukkale Üniversitesi Mühendislik Bilimleri Dergisi
Pages I - III

2. SIMILARITY ANALYSIS OF UNSTEADY THREE DIMENSIONAL BOUNDARY LAYERS OF A NON-NEWTONIAN MODEL
Muhammet YÜRÜSOY, Mehmet YILMAZ, Mehmet PAKDEMİRLİ
Pages 393 - 397
In this study, three dimensional, unsteady, laminar boundary layer equations of a general model of nonNewtonian fluids are treated. In this model, the shear stresses are considered to be arbitrary functions of velocity gradients. A general boundary value problem modeling the flow over a moving surface with suction or injection is considered. Using Similarity Analysis, we showed that equations admit scaling transformation for the arbitrary shear stress case. The specific forms of the stress functions where richer scaling symmetries exist are derived. We reduce the three-independent-variable partial differential system to two-independent-variable partial differential system. Using further translation symmetries of the outcoming equations, the boundary value problem is successfully reduced to an ordinary differential system.

3. INCREASING THE BREAKDOWN VOLTAGE OF BJT’S AS SWITCHING DEVICES
Mustafa SÖNMEZ
Pages 399 - 403
The electrical parameters of the transistor must be taken into account in the designing of electronic circuit. One parameter, VCBO, is one of the most important parameter for the designer. Using transistor which has the breakdown voltage of 50 V, it is not possible to obtain 80 V pulse output since the output voltage can not exceed the supply voltage. In this work, a new method is presented to obtain output voltage bigger than supply voltage by using more than one transistor.

4. PERFORMANCE OF ROTATING BIOLOGICAL CONTACTORS OPERATING AT DIFFERENT TEMPERATURES
Ali BERKTAY
Pages 405 - 410
An investigation was carried out to define the effects of temperature change on the biological wastewater treatment using a Rotating Biological Contactors (RBC). The major investigation was to establish the optimum operational conditions of the unit and to determine how its efficiency was affected by temperature. During the investigation, the substrate employed was a synthetic wastewater made up frequently in the laboratory. Experimental works were conducted at three constant temperature, 10 °C, 20 °C and 30 °C. There was a considerable increase in efficiency of the unit, measured by removal of organic material, between 10 °C and 20 °C, but much less of a change from 20 °C to 30 °C. These variations were reflected by the rate of formation of total oxidized nitrogen in the unit.

5. ALTERNATIVE REFRIGERANT R-134A
Rasim KARABACAK, Okyar KAYA
Pages 411 - 414
Because of the big damages on the ozone layer given by the refrigerants cloroflorocarbons that has been used up to now, new alternative gases should be developped and product at once. In this study, some informations about alternative to presently used CFCs, R-134A refrigerant’s characteristics and its suitability to cooling systems is given. As it would be understood from these informations there is no objection on using alternative R-134A refrigerant

6. CALCULATION OF STREES CONCENTRATION FACTOR ON THE ORTHOTROPIC ROLLER CHAIN LINK PLATE
Muzaffer TOPCU
Pages 415 - 419
The stress concentration factors for transmission roller chain link plates made of isotropic and orthotropic composite materials have been calculated used the finite element method. The stress concentration factors investigated for three different composite materials (fiber-glass, boron-epoxy, graphite-epoxy) and isotropic roller chain link plate and three different geometry. The composite materials of reinforcement angles are fixed 0 and 90 degree. The stress concentration factors the made of different composite materials and several geometry have been compared and controlled by the fotoelastic experiment.

7. STRESS DISTRIBUTION IN A TOROIDAL RING SECTOR SUBJECTED TO BENDING AND TWISTING
Yaşar PALA
Pages 421 - 427
In this study, stress analysis in a toroidal ring sector with an elliptical cross section composed of two confocal ellipses is considered. Göhner’s method is used in the analysis. The results obtained for the case of pure torsion is superposed with those corresponding to pure bending in order to reach to the case of combined loading.

8. DECREASING HEAT TREATMENT COST OF SURFACE HARDENED MACHINE PARTS BY CASE CARBURIZATION
Ahmet Çetin CAN, Ali Rıza TARAKCILAR, Yılmaz ÖZMEN
Pages 429 - 433
Machine parts are surface hardened to increase fatigue strength and wear resistance. Carburization is the most common surface hardening process in practice. In order to have optimum properties, a machine part must have certain hardness depth. To obtain required hardness depth, the parts must be kept in a carburizing medium at certain temperature for certain time. As the time and temperature is increased hardness depth increases. In practice, carburization temperature is about 930 °C. Machine parts are kept at this temperature for required time depending on required hardness depth. The increase of temperature reduces treatment time, considerably. But, heat treaters do not tend to use high temperatures due to the concern of distortion of parts, and deterioration of mechanical properties. In this study, the increase of temperature for reducing carburization time in salt bath, and consequently change of mechanical properties have been investigated using DIN C20 case carburization steel. As a result of experiments, it was found that mechanical properties were not effected negatively.

9. JOINTING PROCESS OF THE SAE 1020 WITH MAG WELD’S REGION HAVE BEEN INVESTIGATED AND FACTOR OF MISMATCH DETERMINED
Cevdet MERİÇ, Mesut TOKDEMİR
Pages 435 - 440
In this study, the jointing process of the SAE 1020 low carbon steel, generally used in the industry, has been done by the MAG weld method. The aim of this study is to examine the mismatch between base and weld metal. After the jointing process, mechanical and metalographical properties of the weld region, HAZ, and the weld metal of the samples considered here were searched, and CTOD (Crack Tip Opening Displacement) was identified.

10. INVESTIGATION INTO THE EFFECTS OF SILISIUM IN ALUMINIUM ALLOYS ONTO THE MECHANICAL PROPERTIES OF WELDING JOINT
Nurettin YAVUZ
Pages 441 - 445
Since aluminium is a good heat and electric conductor, opaque and especially has high strength per unit weight when alloyed, it has widespread using areas in industry. The weldeability of aluminium and aluminium alloys and improvement of mechanical properties of welded parts will extend the usage area. In this study, the parts manufactured by adding Cu 1 % and Si 2, 3, 4, 5 % to Etial 7 aluminium material has been welded using Metal Inert Gas (MIG) technique. Mechanical properties of welding joint have been examined by hardness, tension and impact tests.

11. TRAFFIC NOISE IN KONYA AND SOME PROPOSALS
Mehmet Emin AYDIN, Nuray ATEŞ
Pages 447 - 456
In this study, the results of an investigation on traffic noise in Konya are presented. The aim of the study is to determine the traffic noise in Konya and to investigate possible solutions to reduce the traffic noise. Noise levels are measured on ten different streets between 9 00 - 17 00 hours and the results are evaluated. As a result of this investigation, the noise levels on the streets considered are found to be exceeding the noise levels given by the regulations. Some proposals are suggested in order to reduce the noise levels.

12. SOME PHYSICAL AND CHEMICAL PROPERTIES OF THE RICE GROWN SOILS OF CENTRAL ANATOLIA REGION
Süleyman TABAN, Mehmet ALPASLAN, Aioub G. HASHEMI, Dürdane EKEN
Pages 457 - 466
The aim of this study was to determine the fertility status of the rice grown soils of Central Anatolia region. For this purpose, 40 soil samples were taken and analyzed for some physical and chemical properties. In general, the experimental soils were clay and loamy clay in texture, medium alkaline in reaction (pH) and moderately calcareous. 60, 25, 30 and 95 % of the soils studied were found to be deficient in total-N, plant available phosphorus, zinc and manganese, respectively. On the other hand, 60 % of the soil samples were found to be excess in boron. The salinity levels of the soil samples were seemed to be under salinity limits. 90 % of soils were determined > 25 me/100 g soils in CEC (cation exchange capacity). It was also concluded that 45 % of the soils have low organic matter content.

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