1984 Cilt 1 Sayı 1

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https://hdl.handle.net/11452/31800

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Open Access
Prediction of some turbulent flows using upwind and hybrid discretısa tion schemes and the two-eouation turbulence model
(Uludağ Üniversitesi, 1984) Choudhury, P. Roy; Gerstein, M.; Karasu, Tahir; Uludağ Üniversitesi/Mühendislik Fakültesi/Makine Mühendisliği Bölümü.
The paper presents the use of a numerical solution procedure for the prediction of steady, in compressible and two-dimensional turbulent flow in a pipe, in sudden expansions in pipes, and over a back ward-facing step using upwind and hybrid discretisation schemes. The numerical procedure employs a two-equation turbulence model, which entails the solution of two differential equations of transport for characteristics of turbulence; nameIy, the kinetic energy of turbulence and its rate of dissipation. The Reynolds stresses are related to the mean velocity gradients through a scalar turbulent viscosity, calculated from the above turbulence variables. In the near-wall regions, wall functions are employed. The predictions results from simultaneous solution of differential equations for conservation of mass and momentum, together with equations describing the transport of turbulence, by means of a finite-difference solution procedure. The predictions obtained using upwind and hybrid discretisation schemes are compared with each other and with published experimental data. For flows in which recirculation is present, the use of hybrid scheme results in closer agreement with measurements. In general, the predictions made are in good qualitative agreement with experiment.
Open Access
Prediction of turbulent swirling flows in annuli
(Uludağ Üniversitesi, 1984) Spalding, Brian D.; Karasu, Tahir; Uludağ Üniversitesi/Mühendislik Fakültesi/Makine Mühendisliği Bölümü.
The paper presents the use of a numerical solution procedure for the prediction of steady, in compressible, and two-dimensional axisymmetric turbulent swirling flows in annuli. The mathematical model comprises differential equations for continuity, momentum, turbulence kinetic energy and its rate of dissipation. The simultaneous solution of these equations by means of a finite-difference solution algorithm yields the values of the variables at all internal grid points in the flow domain. The numerical solution procedure, composed of the mathematical model and its solution algorithm, is applied to predict the fields of variables within annular ducts; the results of predictions are compared with published experimental data. The predicted results for turbulent flow in a vertical large-gap annulus with both rotating and non-rotating inner cylinder, and for turbulent swirling flow in a stationary annulus with a rotating inlet were in generally good agreement with experimental measurements reported in the literature.
Open Access
Effecfs of gravity on interdendritic fluid flow in large remelted ingots
(Uludağ Üniversitesi, 1984) Yerebakan, Metin; Uludağ Üniversitesi/Mühendislik Fakültesi/ Makine Mühendiliği Bölümü.
This paper presents analytic calculations of the interdendritic fluid-flow in mush zones whose width is small compared to their length, a situation which is caracteristic of large remelted ingots. The flow is found to consist of two main components. The first one is normal to the isotherms which feeds solidification shrinkage and the second one is parallel to the isotherms which is produced by gravity acting on desity differences in the interdendritic liquid. If the isotherms are not exactly parallel, then the gravity induced flow parallel to the isotherms induces a component normal to it. This companent may cause the freckles that occur in remelted ingots when melting conditions are changed.
Open Access
Elastic and geometric stiffness matrices for thın walled stiffener element
(Uludağ Üniversitesi, 1984) Saylan, Şerif; Toridis, Theodore
Elastic and geometric stiffness matrices for a structural stiffener member are obtained using the differential equations given by Chen and Atsuta 4. Presence of additional elements over the conventional form is observed in the geometric Stiffness matrix. The known transformation matrix is used to express the elements displacements with respect to the middle surface of the stiffened plate.
Open Access
Otomotiv endüstrisindeki gelişmeler
(Uludağ Üniversitesi, 1984) Borat, Oğuz; Uludağ Üniversitesi/Mühendislik Fakültesi/Makina Bölümü.
The problems of the automotive industries, arised by the various constraints such as air pollution, decrease of fossil fuels, usage of alternative fuels, noise pollution, safety, fuel economy, etc., are studied under the titles of alternative fuels, alternative engines and technical improvements. Resultingly, the research subjects and the technological trends, required for solutions reductions of the problems to be faced in the short and long terms, are discussed.
Open Access
Mass specfrometer in investigation of the annealing process of the thermoluminescence phosphore
(Uludağ Üniversitesi, 1984) Selçuk, Ata; Uludağ Üniversitesi/Mühendislik Fakültesi.
Annealing process which is very important to obtain stable thermoluminescence character of the radiation dosimeters is investigated by using the Bendix 2001 GC-MS Time of Flight (T.O.F.) mass spectrometer. Natural calcium fluorite (No: 18, blue) is subjected to the annealing process in the range of 650°C and the evolved gases are recorded by mass spectrometer instantaneously. (m/e), 12, 15, 16, 17, 18, 20, 22, 24, 25, 26, 27, 28, 39, 40, 41 , 42, 43, 44 peaks are detected. This experiment has not performed to analyse the evolved gases and resudues in the sample. But instead to show a way how this can be done using a mass spectrometer.
Open Access
Açık uç (open-end) iplikçiliğinde kullanılan lif açma mekaizmaları
(Uludağ Üniversitesi, 1984) Özipek, Bülent; Uludağ Üniversitesi/Mühendislik Fakültesi/Tekstil Mühendisliği Bölümü.
In the present paper, the main features of open-end spinning which is one of the new spinning methods and has commercially developed at present time are summarized and fibre opening devices used in this spinning system are explained. It has been said that among the opening devices developed miniature taker-in type opening rollers are largely used and this type of opening roller has been described in detail. Also, it has been pointed out that the speed of opening roller has an effect on spinning performance.
Open Access
Elektro-hidrolik aç-kapa (on-off) valflar
(Uludağ Üniversitesi, 1984) Yüksel, İbrahim; Uludağ Üniversitesi/Mühendislik Fakültesi.
This paper describes elektrohydraulic systems and elektro-hidraulic control valves used in these systems. Especially, operations of new developing on-off digital electro-hydraulic systems, which could be used in digital electro-hydraulic systems, have been investigated. Furthermore, on-off type of free floating disc valves are described. The single-dise valve, while having the merit of simplicity, was found to have a signifıcant steady state power loss when using a 25 mm diameter dics size. Due to this, lts main application is thought to be as a miniature pilot or first stage valve, as it could be manufactured to less than half the present size. The double-dise valve, while being more complex, has the important advantages of no quiescent power loss and low sensitivity to particle contamination
Open Access
Atkı atma ve acızlık açma sistemleri açısından dokuma makinalarının günümüzdeki durumu
(Uludağ Üniversitesi, 1984) Alpay, H. R.; Uludağ Üniversitesi/Mühendislik Fakültesi/Tekstil Mühendisliği Bölümü.
In the present paper, the picking and the shedding mechanisms of weaving machines are studied and explanations about the commonly used systems are given. The picking mechanisms are emphasized, in particular, those which are of the most importance are explained in detail. The shedding mechanisms are briefly described from the point of view of their importance on the fabric design. A conclusion has been made.
Open Access
Atomizasyon yöntemi ile metal tozları üretimi ve endüstriyel uygulamaları
(Uludağ Üniversitesi, 1984) Yerebakan, Metin; Uludağ Üniversitesi/Mühendislik Fakültesi/Makina Mühendisliği Bölümü.
Processing of powder materials begins with consideration of the powder properties and caracteristics such as size, shape, composition and structure. These powder features affects the response of subsequent compaction. sintering and densitication processes. Considerable effort is directed toward improved understanding of powder production-method called "atomisation" is reviewed, The mostflexible process in high tonnage production is atomisation since it provides the capability to produce gich quality alloy powders and affords greatest control over powder properties.
Open Access
Normal tipteki zorlanma telleri (strain gauge) ve bir zorlanma göstericisinin (strain indicator) ardarda sıcaklık ve zorlanma ölçümünde kullanımı
(Uludağ Üniversitesi, 1984) Aksel, Hikmet; Uludağ Üniversitesi/Balıkesir Mühendislik Fakültesi.
The use of the strain gauges at normal typ anda strain indicator for the measurement of temperature and the strain subsequently. At this study it was investigated the use of strain gauges which are used for the analyse of the strees-strain for measurement of temperature and the strain. For this purpose 8 type of strain gauges were sticked to the 4 type of surface, then strain curves were determined according to temperatures. On the other hand, some factors affecting the experiments were investigated as well. Afterwards, practical applicability of this method was discussed theoretically. As a result, by using two different strain gauges and a strain indicator, both temperatures with 0,1 °C/u/m sensitivity and strain could be determined supsequently.
Open Access
Hafif inşaat malzemeleri
(Uludağ Üniversitesi, 1984) Erdinç, Hayri; Uludağ Üniversitesi/Balıkesir Mühendislik Fakültesi/İnşaat Mühendisliği Bölümü.
Lightweight aggregates are materials weighing less than usual aggregates of sand, gravel and crushed rock. They may be natural such as pumice, pumicite, diatomite and some vegetable products or manufactu red materials of heat operations i ncluding expanded perlite, vermiculite, day, shale, slate, cooled slags and coal breeze. Lightweight aggregates are used more widely in construction of multistory and commercial building, bridge decks, highway roads and other structures. Besides weighing less, these raw materials are ex cellent insulator and refractory. Some of them have applications in fıltration and agricultural secteurs. The industry of lightweight materials has progressed in the developed countries. These countries consume more than 70~0 percent of world's production. The domestic industry of these raw materials has not improved greatly in Turkey. But the production of expanded perlite has been accelerated to gain repo tation following USA and Russia. lt is hoped that lightweight aggregates will be considered to be valid and be used increasingly in constructions.
Open Access
Durgunluk noktası ve kuyulara permenan olmayan akım
(Uludağ Üniversitesi, 1984) Topacık, Dinçer; Eroğlu, Veysel
In this paper, stagnation point has been determined in the aquifers with a sloping piezometric surface. Formation constants and drawdowns have been calculated by the Theis equation and Jacob approach.
Open Access
Halk sanatı el örme desenlerinin modern örme makinalarında uygulanması
(Uludağ Üniversitesi, 1984) Tasmacı, Mehmet; Uludağ Üniversitesi/Mühendislik Fakültesi/Tekstil Mühendisliği Bölümü.
Die Handstrickerei, wie man sagen kann, began mit dem Bekleidungsgefıihl von Menschen seit früherer Zeiten. Eine Handstrickerei ist nicht anders als von einem einfachen strickerei bis zur Herstellung von Maschenwaren, mit der Hilfe von einfachen Geraten. Die Eigenart ist hier, dem man mit einem guten Geführt und Geschmak mit anzierenden Farben ein Gebilde produziert wird. Die Handstrickerei und ihre Mustern haben für die Entwicklung zu den heutigen und modernen Maschienen viel beigetragen. Mit der Hand lange Zeit dauernde Erzeugung von Muster wird mit der Mas chienen so kurzer zeit gefertigt, mit modernen Strick-und Wirkmaschienen kann man mit einfaden und Kettfaedenprinzip arbeiten und sie sind die Flach-und Rundstrickform gebaut worden. lhre Nadeln können so wohl einzelne als auch zusammen sich bewegen lassen und je nach dem, wird sie automatischweise mechanisch und elektronisch gesteuert. Die Fertigstellung der Mustern werden hier mit Jacguard-und Farbeiurichtung, Umhaenge-und Versatzeinricht~ngen, Ajour, Plattier, lntersia-und Einstreichtechniken durchgefıihrt.
Open Access
Yeni bir dipolmetre yapımı ve polar maddelerin dipol momentinin tayini
(Uludağ Üniversitesi, 1984) Sılay, İlhan; Uludağ Üniversitesi/Balıkesir Mühendislik Fakültesi.
In this study a new dipalemeter was constructed in order to determine the dipole moments of polar liquids. The resonance circuit was controlled by means of a quartz crystal of 1 M Hz and two variable precision condensers and an EM 80 lamp were used for this purpose. As an energy source, a 250 volt regulated stable source was prepared. Useful were given about the calibration method of the instrument; the advantageous capacity of the sample cell was found, anda phenol solution was prepared under 25° C in four different benzen concentrations and by the help of a dipalemeter the dipole moment value of the polar liquid was determined. The value found compared with the one in the literature.
Open Access
Şair matematikçi Ömer Hayyam
(Uludağ Üniversitesi, 1984) Erdoğan, Hakkı İsmail
Bugünkü konuşmamda, elde edebildiğim dökümanlar çerçevesinde, sizlere Ömer Hayyam'ı tanıtmaya çalışacağım. Öncelikle, bir matematikçi olmama rağmen, neden böyle bir konuyu seçtiğimi söylemek istiyorum. Her batılı bilim adamı , literatürde, yaptığı bilimsel çalışmalarıyla anılır . Oysaki bilime pek çok katkısı olan birçok şarklı kimselerin literatürde adları geçmediği gibi, yaptığı çalışmalar da, garplı bilimcile rin-onların bilime katkısıymış gibi- söylenir. Işte ben bugün hiç değilse böyle şarklı bilim adamını, bugü ne kadar NEWTON ve diğer ünlülere ait olduğunu zannettiğiniz bir çok çalışmaların gerçek sahibi olduğunu çeşitli yabancı kaynaklara istinaden açıklayacağım. lsteğim odur ki bilimsel çalışmalar gerçek sa hiplerinin ismi ile anılsın .
Open Access
Sendikalar ve ekonomi politikası: Batı deneyimi ve ülkemiz açısından bir değerlendirme
(Uludağ Üniversitesi, 1984) Yücel, Asım; Uludağ Üniversitesi/Balıkesir Mühendislik Fakültesi.
In this study, we analized the possible ways and the mechanism that trade unions in a market economy could join and contribute in formulating and exerdsing of national economic policies, and the practical experiences of some advanced countries of the West including that of the U.S.A. Summarizing the basic characteristics of western practices we concluded that, tradeunionsin Turkey, taking account of the western experiences as well as their own ones in the past, might/and should cooperate with the government in solving such fundamental economic problems as inflation and unemployment in Turkey today.
Open Access
Yaşanabilir kentsel çevrede donatım faktörleri ve bir yöntem saptaması
(Uludağ Üniversitesi, 1984) Eren, Deniz
Konuya kentsel olgunun "urbanistik" tanımlaması ile başlamak istiyorum. Ancak ne varki çok farklı yaklaşımların ortak kriterlerinin saptanmasında yarar görüyorum. Kent dediğimiz olgu bir "değişim merkezi" dir. Öncelikle maddi değişimi anımsamak gerekir. Mal ve hizmet değişimi En genel anlamıyla "değişim" diye nitelendirilen bu olgu günümüzde "çağdaş medeniyetin" bir simgesidir. Çağımız ile özdeşleştirilen bu medeniyetin ortaya koyduğu ürünler çoğu kez insanlık için düşün dürücü olmaya başlamıştır. Bahis konusu insan olmanın tüm erdemlerinin yitirilmesi ile karşı karşıya kalın dığında konu daha da büyük boyutlar kazanmaktadır . insanlığın gelişimi evrelerinde;günümüze dek devam edegelen süreç içinde hangi tarihsel kesit ele alınırsa alınsın, bugün sahip olduğumuz teknik olanakların bin de birine sahip değildi.
Open Access
Mimaride güneş kontrolü
(Uludağ Üniversitesi, 1984) Reman, Orhan; Uludağ Üniversitesi/Balıkesir Mühendislik Fakültesi.
Yeryüzündeki canlılar için güneş ışınımının hayat ve sağlık kaynağı olduğunu biliyoruz. Mekan düzenlemesinde en önemli unsur fonksiyona göre düzenlenmiş hacmin insan fızyolojisine en uygun aydınlanma ve güneş ışınımından yararlanabilmesi olmalıdır . Herhangi bir bölgede planlanmış bir proje için direkt güneş ışınımının günün çeşitli saatlerinde kış ve yaz aylarında kaç derecelik açı altında mekan içerisine girdiğini hesaplamak gerekir. Burada iki önemli açı söz konusudur. Bunlardan Azimut açısı; güneş ışınlarının geldiği yönü, Yükseklik açısı ise; bu yönde gelen ışınımın kaç derece açı ile geldiğini açıklamaktadır.
Open Access
Serçeören (Kepsut-Balıkesir) vollastonit yatağı
(Uludağ Üniversitesi, 1984) Erdinç, Hayri; Uludağ Üniversitesi/Balıkesir Mühendislik Fakültesi/İnşaat Mühendisliği Bölümü.
Vollastonit Türkiye için oldukça yeni bir hammaddedir. ilk üretimi 1968 yılında Serçeören yatağından yapılmıştır. Serçeören köyünün kuzeydoğusundaki kontakt metamorfızma kuşağında yer alan kalksilikat felslerin ana minerali olan vollastonit'e eşlik eden minerallerin bazıları granat, diyopsit, forsterit, vezüvyanit ve tremolittir. Bu alanda 500.000 ton kadar vollastonit tahmin edilmektedir. Günü müze değin, aralıklı olarak yapılan üretimle 100.000 ton saf vollastonit seramik endüstrisinde kullanmak için tüketilmiş , geriye % SO civarında vollastonit içeren kalksilikat felsler kalmıştır. Bunlardan yararlanıl ması zenginleştirme işlemlerinin geliştirilmesine bağlıdır . Kuzeybatı Anadolu'da yer alan asid bileşimli intrüsif kayaçiarın çevrelerinde birkaç yerde vol lastonit oluşumları bilinmekte olup, yenilerinin bulunma olasılığı oldukça yüksektir.