Mechanical Engineering / Makina Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/4129
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Article Power transmission entropy(Inderscience Enterprises Ltd., 2008) Özdemir, SerhanMechanical transmissions have been characterised traditionally by their transmission efficiencies. This is given by the ratio of the output to the input of the transmitted power. Unfortunately, the power transmission phenomenon is slightly more complex than that. As any designer would agree, each of these transmission localities is a source of uncertainty. Once formulated, this statement of uncertainty would reflect the designer's trust in the transmission. By virtue of the proposed approach, power transmission is no longer a deterministic entity but becomes a probabilistic one. This paper discusses the overlooked uncertainty inherent in every transmission.Article Virtual Prototyping for Robot Controllers(Inderscience Enterprises Ltd., 2010) Dede, Mehmet İsmet CanProduction of a new mechanism involves design, manufacturing and testing phases. In order to achieve shorter turn-around times, researchers have studied methods of shortening these phases. Today, structural tests and simulations conducted in virtual environments prior to manufacturing are a part of most of the standard production processes. However, in robot production not only the structural aspect of the mechanism but also its controller is required to be tested. This paper summarises a versatile method to rapid prototype the robots in virtual environments to conduct controller tests. The verified controllers are then employed in actual robot prototype. The procedure is implemented in a gimbal-based joystick production process.Article Exergetic Analysis of a Continuous Bi-Axially Oriented Polypropylene (bopp) Film Unit in a Plastic Processing Plant(Inderscience Enterprises Ltd., 2009) Balta, M. Tolga; Hepbaşlı, Arif; Hancıoğlu, Ebru; Özcanlı, Şevket Cihangir; Yılmazer, Ertan; Yurdakul, İbrahim; Dişbudak, ÖzgürThis paper deals with an exergy analysis of the stretching process of bi-axially oriented polypropylene films using a hot oil coiler along with stretching and crystallising unit. Exergy destructions and efficiencies in each of the system components are calculated, while the exergy loss and flow diagram (the so-called Grassmann diagram) is presented for the transverse direction (TD) unit. The so-called functional (on the product or benefit/fuel basis) and universal (on the output/input basis) exergy efficiency values of the TD unit are calculated to be 26.40% and 28.46% at a recommended exhaust air relative humidity of 0.0098 kg water/kg air, respectively.Article Citation - WoS: 12Citation - Scopus: 19Effect of Non-Condensable Gases on Geothermal Power Plant Performance. Case Study: Kızıldere Geothermal Power Plant-Turkey(Inderscience Enterprises Ltd., 2008) Gökçen Akkurt, Gülden; Yıldırım, NurdanNon-Condensable Gases (NCGs) are natural components of geothermal fluids, and they are a source of considerable capital and operating costs for power plants. The NCG content of geothermal steam varies over the world from almost zero to as much as 25% (wt). In this work, the influence of NCGs on the thermodynamic performance of geothermal power plants is analysed for various NCG content and turbine inlet temperatures. The results obtained can be useful on the feasibility study of single flash geothermal power plants. Depending on the NCG content of the field, the performance of the power plant can be determined roughly. © 2008, Inderscience Publishers.Article Citation - Scopus: 10Exergy Analysis and Performance Evaluation of Kizildere Geothermal Power Plant, Turkey(Inderscience Enterprises Ltd., 2004) Yıldırım, Eda Didem; Gökçen Akkurt, Gülden; Gökçen, GüldenConventional geothermal power plants (GPP) differ from fossil-fuel power plants (FFPP) in many ways. The most specific ones are GPPs, are not cyclic plants and the working fluid is not pure steam. Geothermal steam contains non-condensable gases (NCG) which degrade power plant efficiency. This discrepancy leads to two considerations in energy and exergy analysis of GPPs. One is that the amount of NCGs in the steam cannot be omitted during the calculations; the other is that the dead state composition varies throughout the process. In this work, energy and exergy analysis is conducted to assess the performance of Kizildere GPP under both considerations. The net second law efficiencies of the plant based on reservoir and wellhead exergy are 24.3 and 27.2% respectively. Both indicate that the plant performance is low comparing with the other single-flash GPPs and FFPPs. The losses are mainly associated with high NCG content and low steam fraction of the fluid.Article Citation - WoS: 2Citation - Scopus: 3Effect of Voxel Size in Flow Direction on Permeability and Forchheimer Coefficients Determined by Using Micro-Tomography Images of a Porous Medium(Inderscience Enterprises Ltd., 2015) Uçar, Eren; Mobedi, Moghtada; Altıntaş, Gökhan; Glatt, ErikThe permeability and Forchheimer coefficients of a porous medium, volcanic rock, are determined using micro-tomography images. A cubic volume in the middle of the images is extracted as REV (representative volume). The voids in the REV are discretised into anisotropic voxels using the commercial program of GeoDict. Seven computational domains with different voxel size in flow direction are generated. The velocity and pressure fields in the voids are obtained for Reynolds numbers ranging from 0.01 to 10. The obtained fields are used to determine the permeability and the Forchheimer coefficients. The performed calculations show that the nominal pore size changes with the voxel size in flow direction, however permeability and the Forchheimer coefficient approaches to the constant values.