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Fevzi C. KivancAuthor VitaeShawn LitsterAuthor Vitae 《Sensors and actuators. B, Chemical》2011,151(2):394-401
This paper presents the use of mesoporous silica skeletons as substrates for electroosmotic (EO) micropumps. Mesoporous silica skeletons have bimodal pore size distributions consisting of macropores and cation-permselective mesopores. These materials have the potential for high flow rate per power because the cation-permselective mesopores can generate an induced charge layer (ICL) and electroosmosis of the second kind (EO-2) under high applied electric fields. The diffuse charge layers induced by the electric field result in an EO-2 flow rate that increases quadratically with increasing electric field. In contrast, the flow rate of the more common electroosmosis of the first kind (EO-1) is linearly proportional to electric field. Here, we investigate the impact of finite pressure loads on the EO-2 flow rate with experiments and an engineering model to evaluate the potential of mesoporous skeletons for micropumping applications. Our results include analyses of maximum flow rate, maximum pressure, and flow rate with intermediate pressure loads. The results indicate the existence of a critical pressure load at which reverse pressure-driven flow significantly diminishes the EO-2 flow. We also investigate the scaling of flow rate per power with respect to substrate thickness and area, demonstrating significant increases in flow rate per power with thinner substrates and favorable scaling for miniaturization of EO-2 pumps. 相似文献
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Abdulaziz Guneroglu Fevzi Karsli Mustafa Dihkan 《International journal of remote sensing》2013,34(13):4702-4714
Riverine fresh water outflows create coastal plumes that are distinguished from surrounding sea water by their specific spectral signature. Coastal waters are unique ecosystems, and they are very important in terms of living resources and oceanographic processes. River plumes and coastal turbid waters have important effects on coastal marine ecosystems, and they also influence marine life cycles, sediment distribution, and pollution. Remote sensing and digital image-processing techniques provide an effective tool to detect and monitor these plume zones over large areas. The primary goal of this study was automatic detection and monitoring of coastal plume zones using multispectral Landsat Thematic Mapper/Enhanced Thematic Mapper Plus (TM/ETM+) imagery. For that purpose, the proposed algorithm exploits spectral features of the multispectral images by using feature extraction and decision-making steps. The procedure has two main stages: (1) some pre-processing operations were applied to the images in order to extract the plume core reflectance values with maximum turbidity and offshore water mass reflectance values; (2) a k-means algorithm was applied with initial seed values of reflectance computed from the pre-processing stage to classify coastal plume zones. Spatial pattern and variability of optical characteristics of coastal plume zones were then defined following the results of the classification process. The algorithm was automatically applied in three different regions with three multispectral Landsat images acquired on different dates, and yielded a very high classification accuracy in detecting coastal plume zones. 相似文献
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Fevzi Bedir 《Journal of Mechanical Science and Technology》2006,20(7):1002-1011
In this study, we describe the conventional hot pressing (CHP) of layered Al-B4C composites and their characterization. The matrix alloy A1-5 wt.%Cu was prepared from elemental powder mixtures. The metal
and B4C powders were mixed to produce either Al-Cu-10vol.%B4C or Al-Cu-30vol.%B4C combinations. Then, these powder mixtures were stacked as layers in the hot pressing die to form a two-layered composite.
Hot pressing was carried out under nitrogen atmosphere to produce 30×40×5 mm specimens. Microstructural features and age hardening
characteristics of composites were determined by specimens cut longitudinally. The flexural strength of both layered composites
and their monolithic counterparts were investigated via three point bending tests. In the case of layered specimens of both
10vol.%B4C and 30vol.%B4C containing layers were loaded for three-point test. The results show that a homogeneous distribution of B4C particles in the matrix alloy which is free of pores, can be obtained by CHP method. The ageing behavior of the composites
was found to be influenced by the reinforced materials, i.e. higher hardness values were reached in 8 hrs for the composites
than that for the matrix alloy. Flexural strength test showed that two-layered composites exhibited improved damage tolerance
depending on layer arrangement. Microstructural investigation of the fracture surfaces of the bending specimens was performed
by means of scanning electron microscope (SEM). While layer with lower reinforcement content exhibited large plastic deformation
under loading, the other with higher reinforcement content exhibited less plastic deformation. 相似文献
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Hayrettin Acar Fevzi Karsli Mehmet Ozturk Mustafa Dihkan 《International journal of remote sensing》2019,40(1):138-155
Three-dimensional (3D) spatial information of object points is a vital requirement for many disciplines. Laser scanning technology and techniques based on image matching have been used extensively to produce 3D dense point clouds. These data are used frequently in various applications, such as the generation of digital surface model (DSM)/digital terrain model (DTM), extracting objects (e.g., buildings, trees, and roads), 3D modelling, and detecting changes. The aim of this study was to extract the building roof points automatically from the 3D point cloud data created via the image matching techniques with optical aerial images (with red, green, and blue band (RGB) and infrared (IR)). In the first stage of the study, as an alternative to laser scanning technology, which is more expensive than optical imaging systems, the 3D point clouds were produced by matching high-resolution images using a Semi Global Matching algorithm. The normalized difference vegetation index (NDVI) values for each point were calculated using the spectral information (RGB + IR) in the 3D point cloud data, and the points that represented the vegetation cover were determined using these values. In the second stage, existing ground and non-ground points that were free of vegetation cover were determined within the point cloud. Subsequently, only the points on the roof of the building were detected automatically using the proposed algorithm. Thus, points of the roofs of buildings located in areas with different topographic characteristics were detected automatically detected using only images. It was determined that the average values of correctness (Corr), completeness (Comp), and quality (Q) of the pixel-based accuracy analysis metrics were 95%, 98%, and 93%, respectively, in the selected test areas. According to the results of the accuracy analysis, it is clear that the proposed algorithm is very successful in automatic extraction of building roof points. 相似文献
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Kilincceker Onur Turk Ercument Belli Fevzi Challenger Moharram 《Software and Systems Modeling》2022,21(3):1209-1240
Software and Systems Modeling - An ideal test is supposed to show not only the presence of bugs but also their absence. Based on the Fundamental Test Theory of Goodenough and Gerhart (IEEE Trans... 相似文献
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C. Erdinc Tas Saman Hendessi Mustafa Baysal Serkan Unal Fevzi C. Cebeci Yusuf Z. Menceloglu Hayriye Unal 《Food and Bioprocess Technology》2017,10(4):789-798
Novel polymeric active food packaging films comprising halloysite nanotubes (HNTs) as active agents were developed. HNTs which are hollow tubular clay nanoparticles were utilized as nanofillers absorbing the naturally produced ethylene gas that causes softening and aging of fruits and vegetables; at the same time, limiting the migration of spoilage-inducing gas molecules within the polymer matrix. HNT/polyethylene (HNT/PE) nanocomposite films demonstrated larger ethylene scavenging capacity and lower oxygen and water vapor transmission rates than neat PE films. Nanocomposite films were shown to slow down the ripening process of bananas and retain the firmness of tomatoes due to their ethylene scavenging properties. Furthermore, nanocomposite films also slowed down the weight loss of strawberries and aerobic bacterial growth on chicken surfaces due to their water vapor and oxygen barrier properties. HNT/PE nanocomposite films demonstrated here can greatly contribute to food safety as active food packaging materials that can improve the quality and shelf life of fresh food products. 相似文献