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71.
Serkan Şimşek Sasan Ahdi Rezaeieh 《AEUE-International Journal of Electronics and Communications》2013,67(11):981-983
An efficient design method for substrate integrated waveguide electromagnetic bandgap (SIW-EBG) filters is proposed which provides direct dimensional synthesis approach for desired filter objectives without using network representations. The method is applied to the design of an X band SIW-EBG filter and its response is compared with HFSS (high frequency structure simulator) simulations for validation purposes. Fairly good agreement between the results shows the applicability of the proposed method for SIW-EBG filter design. 相似文献
72.
Ahmet Avcı Nevzat İlkaya Mehmet Şimşir Ahmet Akdemir 《Journal of Materials Processing Technology》2009,209(3):1410-1416
In the present experimental study, strengthening of gray cast iron by reinforcing with steel plates was investigated in the as-cast and normalized conditions. Normalizing heat treatments were applied to the specimens at temperatures of 800 °C and 850 °C. Three-point bend specimens were manufactured from gray cast iron and also from gray cast iron with reinforced steel plates. Flexural strengths of the steel-plate-reinforced cast iron were calculated for four distinct volume fractions (Vr = 0.04, 0.08, 0.12, and 0.16). The current study shows that the steel-plate-reinforced gray cast iron has higher flexural strength and flexural modulus than the cast iron without reinforcement. The flexural strength considerably increases with slight increase in normalization temperature. Optical and scanning electron microscopy analyses were used to examine flake morphology and microstructures of gray cast iron and steel-plate-reinforced gray cast iron. It is noted that carbon diffuses from the gray cast iron to the steel plates. A transition region containing partially dissolved graphite and having high hardness was observed due to the carbon diffusion. 相似文献
73.
Hilal Şahin Ayhan Topuz Monika Pischetsrieder Feramuz Özdemir 《European Food Research and Technology》2009,230(1):155-161
Roasted carob powder was obtained using different time–temperature combinations and some quality characteristics such as total
phenolic content (TPC), total antioxidant activity (TAA), browning index (BI) at 420 nm, UV absorbance (UV-A) at 294 nm, and
pH has been investigated. Both the roasting temperature and time significantly (P < 0.01) affected the quality characteristics of the product. However, the roasting time was found to be a critical factor
in determining the overall quality of the product. While the TPC, TAA, BI and UV-A values of the samples increased with the
increasing roasting temperature and time, the pH of the samples decreased gradually. The quality characteristics of the carob
powders changed markedly in between 20 and 60 min of roasting which indicates that the heat-induced reactions accelerate particularly
in that period of roasting. The correlations between all these chemical properties of carob powder were found to be significant
(P < 0.0001) during roasting. 相似文献
74.
A promising line of research for radar systems attempts to optimize the detector thresholds so as to maximize the overall performance of a radar detector–tracker pair. In the present work, we attempt to move in a direction to fulfill this promise by considering a particular dynamic optimization scheme which relies on a non-simulation performance prediction (NSPP) methodology for the probabilistic data association filter (PDAF), namely, the modified Riccati equation (MRE). By using a suitable functional approximation, we propose a closed-form solution for the special case of a Neyman–Pearson (NP) detector. The proposed solution replaces previously proposed iterative solution formulations and results in dramatic improvement in computational complexity without sacrificed system performance. Moreover, it provides a theoretical lower bound on the detection signal-to-noise ratio (SNR) concerning when the whole tracking system should be switched to the track before detect (TBD) mode. 相似文献
75.
İilknur Demiral Sevgi Şensöz 《Energy Sources, Part A: Recovery, Utilization, and Environmental Effects》2013,35(12):1149-1158
Fixed-bed slow pyrolysis experiments have been conducted on a sample of hazelnut bagasse to determine particularly the effects of pyrolysis temperature, heating rate, particle size and sweep gas flow rate on the pyrolysis product yields. The temperature of pyrolysis, heating rate, particle size and sweep gas flow rate were varied in the ranges 350–550° C, 10 and 50° C/min, 0.224–1.800 mm and 50–200 cm3/min, respectively. Under the various pyrolysis conditions applied in the experimental studies, the obtained char, liquid, and gas yield values ranged between 26 and 35 wt%, 23 and 34.40 wt%, and 25 and 32 wt%, respectively. The maximum biooil yield of 34.40% was obtained at the final pyrolysis temperature of 500°C, with a heating rate of 10° C/min, particle size range of 0.425–0.600 mm and a sweep gas flow rate of 150 cm3/min. 相似文献
76.
Zeynep Münteha Şahin Erdinç Doğancı S. Zeki Yıldız Murat Tuna Faruk Yılmaz Yusuf Yerli Mesut Görür 《Synthetic Metals》2010,160(17-18):1973-1980
Two-armed poly(?-caprolactone) (TAPCL) polymers were successfully synthesized via the ring opening polymerization (ROP) of ?-caprolactone (?-CL) using the Schiff's base complexes [Cu(SAEE)2] (1) and [Ni(SAEE)2] (2), which have two hydroxyl functional groups, as the two-site initiators and tin(II) 2-ethylhexanoate (Sn(Oct)2) as the catalyst in bulk at 115 °C. The Schiff's base complexes (1 and 2) were synthesized by utilizing the concentrated template synthesis method starting from salicyl aldehyde, 2-(2-aminoethoxy) ethanol and related metal acetate salts. The synthesized TAPCL polymers were characterized by GPC, FTIR, UV–vis, and electron paramagnetic resonance (EPR). The molecular weights of TAPCL polymers linearly increased with increasing molar ratio of the monomer to the initiator. The results obtained from FTIR, UV–vis, and EPR studies indicated that TAPCL polymers had the Schiff's base complexes at the junction point of PCL arms. The crystallization behavior of TAPCL was studied by using differential scanning calorimetry (DSC) and polarizing optical microscopy (POM). Thermal behavior of TAPCL was also investigated by thermogravimetrical analysis (TGA). 相似文献
77.
O. Özşahin A. Ertürk H.N. Özgüven E. Budak 《International Journal of Machine Tools and Manufacture》2009,49(1):25-35
Accurate identification of contact dynamics is very crucial in predicting the dynamic behavior and chatter stability of spindle–tool assemblies in machining centers. It is well known that the stability lobe diagrams used for predicting regenerative chatter vibrations can be obtained from the tool point frequency response function (FRF) of the system. As previously shown by the authors, contact dynamics at the spindle–holder and holder–tool interfaces as well as the dynamics of bearings affect the tool point FRF considerably. Contact stiffness and damping values alter the frequencies and peak values of dominant vibration modes, respectively. Fast and accurate identification of contact dynamics in spindle–tool assemblies has become an important issue in the recent years. In this paper, a new method for identifying contact dynamics in spindle–holder–tool assemblies from experimental measurements is presented. The elastic receptance coupling equations are employed in a simple manner and closed-form expressions are obtained for the stiffness and damping parameters of the joint of interest. Although this study focuses on the contact dynamics at the spindle–holder and holder–tool interfaces of the assembly, the identification approach proposed in this paper might as well be used for identifying the dynamical parameters of bearings, spindle–holder interface and as well as other critical joints. After presenting the mathematical theory, an analytical case study is given for demonstration of the identification approach. Experimental verification is provided for identification of the dynamical contact parameters at the holder–tool interface of a spindle–holder–tool assembly. 相似文献
78.
The synthesis, crystal structure analysis and characterisation of 5-[thiazol-2-yldiazenyl]pyrimidine-2,4,6(1 H ,3 H ,5 H )-trione are reported. This dye was characterised by ultraviolet–visible, Fourier Transform–infrared, proton nuclear magnetic resonance spectroscopy, mass spectrometry techniques and elemental analysis. Both the effects of pH value and solvent polarity upon the absorption properties of the dye have been presented. In addition, the structure of the dye has been determined by a single crystal X-ray diffraction method. The dye was triclinic in P-1 with a = 8.2419(2) Å, b = 10.6225(3) Å, c = 12.5106(3) Å, α = 90.543(1)°, β = 102.79(3)°, γ = 103.858(1)°, V = 1035.26(5) Å3 , D calc = 1.634 g/cm3 and Z = 2. The asymmetric unit contains two crystallographically independent C7 H5 N5 O3 S molecules, alongside one half of the solvent C2 H6 O2 molecule. In the crystal structure, intramolecular N–H…N and intermolecular N–H…N, N–H…O, O–H…N, C–H…O and C–H…N hydrogen bonds link the molecules to form a supramolecular network in which they seem to be effective in the stabilisation of the structure. 相似文献
79.
An automated computer program isdeveloped for calculating areal average rainfall(AAR) value and its implementation is presentedfor the arid region representative country,Libya.The procedure is conceptually simple byconsideration of almost equilateral trianglesconnecting adjacent meteorological stations withthe assumption of linear rainfall change betweenstations. The applications of the methodologyhave been achieved for monthly, seasonal andannual rainfall amounts recorded at 29meteorological stations scattered over thenorthern part of Libya.It has been shown thatthe proposed methodology yields results that arecomparable with the commonly used AAR calculationmethods. 相似文献
80.
Depiction of precipitation change by elevation in an areaindicates the possibilities of orographic rainfall occurrencesin the mountainous regions. In general, precipitation increaseswith elevation but sometimes inverse cases occur locally due toorographic and meteorological features of the area. Inpractice, prior to any quantitative modeling, qualitativeassessments and interpretations help to have sound foundationsin search for a suitable model. In this article, standardizedpoint cumulative semivariogram (SPCSV) methodology is employedfor identification of the precipitation-elevationrelationship. According to relative positions of theprecipitation and elevation SPCSVs four different precipitationcategories are suggested. The application of the methodologyproposed is presented for the precipitation records from YuccaMountain, Nevada, U.S.A. 相似文献