Power quality assessment of grid-connected wind farms considering regulations in turkey

This paper presents measurement system and detailed analysis of power quality at the substation of two different wind farm sites which are of low and high power rate. Measurement system has been designed using a data acquisition board (DAQ), Labview software, Matlab programming and a portable PC. The system has been installed at medium voltage level at substation of both wind farms. The real measurement results at substations are compared to current regulations in Turkey.     

Synthesis,characterization and kinetics of thermal decomposition of various peroxycarbamates and their initiation of methyl methacrylate polymerization

Several dimeric and polymeric peroxycarbamates were synthesized using various aliphatic diisocyanates and hydroperoxides. The products were characterized by IR spectroscopy, molecular weight measurements, isocyanate and peroxide analyses. Thermal decomposition kinetics of these peroxycarbamates were studied in 1,4-dioxane or toluene solutions at 80, 90, and 100°C. All reactions were found to proceed according to a first-order kinetics with activation energies in the range of 126–144 kJ/mol, depending on the structure of the peroxycarbamate. One of the polymeric products was used to initiate methyl methacrylate polymerization at 80°C in bulk. The initiating activity of this peroxycarbamate was found to be better than that of some hydroperoxides.     

An FPGA-based implementation of corner detection and matching with outlier rejection

ABSTRACT

To meet the high frame rate requirements of correct point correspondences with a sub-pixel precision, this paper first proposes a Field Programmable Gate Array (FPGA) architecture that consists of corner detection, corner matching, outlier rejection, and sub-pixel precision localisation. In the architecture, a combined Features from Accelerated Segment Test (FAST)+ Binary Robust Independent Elementary Features (BRIEF) algorithm is adopted for detection and matching with pixel precision, a combined algorithm of Slope-based Rejection (SR) and Correlation-Coefficient-based Rejection (CCR) is used to reject the outliers, and a gradient centroid-based algorithm is used for sub-pixel precision localisation. The whole FPGA architecture is implemented on a single FPGA platform (Xilinx XC72K325T). Five image datasets with different spatial resolutions, textures, lights, rotate angles, and viewpoints are used to evaluate the performance of the FPGA-based implementation. The experimental results show that (1) the SR and CCR algorithms are effective for outlier rejection; (2) a higher correct matching rate is achieved for the image pairs that cover artificial textures than for those that cover natural textures; (3) the proposed architecture is also suitable for image pairs with small change of lights, rotate angles, and viewpoints; (4) the speed of the FPGA-based implementation can reach 280 Frames Per Second (FPS), which is 35 times faster than the Personal Computer (PC)-based implementation; and (5) the usage of FPGA resources is acceptable for the selected FPGA platform. The speed and usage of the FPGA resources can be improved when the whole FPGA-based implementation is further optimised.     

The effect of hydrogen on the electronic,mechanical and phonon properties of LaMgNi4 and its hydrides for hydrogen storage applications

Density functional theory calculations are used herein to explore the effect of hydrogen on the electronic, mechanical and phonon properties of LaMgNi₄ and its hydrides. The polycrystalline elastic moduli, Poisson's ratios and Debye temperatures are calculated based on the single-crystal elastic constants and Voigt-Reuss-Hill approximations. It is also found that all these materials are metallic behavior, ductile and anisotropic in nature. The mechanical anisotropy is discussed via several anisotropy indices and three-dimensional (3D) surface constructions. The effect of high temperature on the free energy, entropy, and heat capacity are also studied by using the quasi-harmonic Debye model. LaMgNi₄ and its hydrides are found to be energetically, mechanically and dynamically stable. Also, they are thermodynamically stable and the order of phase stability is LaMgNi₄H₇ > LaMgNi₄H₄ > LaMgNi₄H > LaMgNi₄. In addition, the highest gravimetric hydrogen storage capacity is found to be 1.74 wt% for LaMgNi4H₇.     

Incorporation of Propionibacterium shermanii subsp. freudenreichii in probiotic dairy drink production: physicochemical,rheological, microbiological and sensorial properties

The aim of this study was to investigate the use of Propionibacterium shermanii subsp. freudenreichii as a combined culture with Lactobacillus acidophilus (AP), Bifidobacterium animalis subsp. lactis (BP), Lactobacillus casei (CP) and Lactobacillus rhamnosus (RP) in probiotic dairy drink production. Although Propionibacterium spp. is used for many purposes including biopreservative and adjunct culture, in this study, probiotic dairy drinks containing P. freudenreichii were evaluated in terms of their physicochemical, rheological, microbiological and sensory properties. The results of the study showed that P. freudenreichii can also be suitable for the production of probiotic drinks and that there are no adverse effects on the product characteristics.     

Effect of feeding pattern on biochemical storage by activated sludge under anoxic conditions

This study investigated the effect of feeding pattern on bacterial storage under anoxic conditions, emphasizing previous adaptation of biomass to a long term feeding condition, under steady-state operation. Storage was evaluated in a sequencing batch reactor (SBR) system operated in a sequence of anoxic/aerobic phases, fed with acetate as the sole carbon source during anoxic conditions. The experimental results indicated that biochemical storage of acetate as PHB occurred when substrate was fed as a pulse, while acetate was removed mostly through direct microbial growth under continuous feeding. For pulse feeding, the anoxic yield, Y(STOD) was calculated as 0.58mg COD (mgCOD)(-1) in two different ways, using mass balances on acetate utilization, PHB generation and nitrate consumption. This value was supported by parallel batch tests and similar results in the literature. Similarly, the rate coefficient for storage under anoxic conditions, k(STOD) was computed as 9.3day(-1) based on basic stoichiometry and model calibration of experimental data. Batch tests conducted with biomass adapted to different feeding patterns showed that substrate storage was insignificant when the feed was added continuously at low concentrations, even if the biomass was previously adapted to storage. Similarly biomass acclimated to continuous feeding could not store the excess substrate although fed instantly. For the operating conditions selected for the study, storage response was significant only with a microbial culture with metabolic activities previously adapted to storage and with short-term substrate feeding at high concentrations.     

Smartphone addiction and its relationship with social anxiety and loneliness

Individuals with psychosocial problems such as social phobia or feelings of loneliness might be vulnerable to excessive use of cyber-technological devices, such as smartphones. We aimed to determine the relationship of smartphone addiction with social phobia and loneliness in a sample of university students in Istanbul, Turkey. Three hundred and sixty-seven students who owned smartphones were given the Smartphone Addiction Scale (SAS), UCLA Loneliness Scale (UCLA-LS), and Brief Social Phobia Scale (BSPS). A significant difference was found in the mean SAS scores (p?<?.001) between users who declared that their main purpose for smartphone use was to access social networking sites. The BSPS scores showed positive correlations with all six subscales and with the total SAS scores. The total UCLA-LS scores were positively correlated with daily life disturbance, positive anticipation, cyber-oriented relationship, and total scores on the SAS. In regression analyses, total BSPS scores were significant predictors for SAS total scores (β?=?0.313, t?=?5.992, p?<?.001). In addition, BSPS scores were significant predictors for all six SAS subscales, whereas UCLA-LS scores were significant predictors for only cyber-oriented relationship subscale scores on the SAS (β?=?0.130, t?=?2.416, p?<?.05). The results of this study indicate that social phobia was associated with the risk for smartphone addiction in young people. Younger individuals who primarily use their smartphones to access social networking sites also have an excessive pattern of smartphone use.     

Effect of the atmospheric plasma treatment parameters on jute fabric: The effect on mechanical properties of jute fabric/polyester composites

The effect of atmospheric air plasma treatment of jute fabrics on the mechanical properties of jute fabric reinforced polyester composites was investigated. The jute fabrics were subjected to different plasma powers (60, 90, and 120 W) for the exposure times of 1, 3, and 6 min. The effects of plasma powers and exposure times on interlaminar shear strength, tensile strength, and flexural strength of polyester based composites were evaluated. The greatest ILSS increase was about 171% at plasma power of 120 W and exposure time of 6 min. It is inferred that atmospheric air plasma treatment improves the interfacial adhesion between the jute fiber and polyester. This result was also confirmed by scanning electron microscopy observations of the fractured surfaces of the composites. The greatest tensile strength and flexural strength values were determined at 120 W for 1 min and at 60 W for 3 min, respectively. Moreover, it can be said that atmospheric air plasma treatment of jute fibers at longer exposure times (6 min) made a detrimental effect on tensile and flexural properties of jute‐reinforced polyester composites. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011