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排序方式: 共有294条查询结果,搜索用时 15 毫秒
21.
Borte Kose Hale Ozgun Mustafa Evren Ersahin Nadir Dizge Derya Y. Koseoglu-Imer Burcu Atay Recep Kaya Mahmut Altınbas Sema Sayılı Pelin Hoshan Doga Atay Esra Eren Cumali Kinaci Ismail Koyuncu 《Desalination》2012
Produced water, which is co-produced during oil and gas manufacturing, represents one of the largest sources of oily wastewaters. Therefore, treatment of this produced water may improve the economic viability and lead to a new source of water for beneficial use. In this study a submerged hollow fiber membrane bioreactor (MBR) has been studied experimentally for the treatment of brackish oil and natural gas field produced water. This type of wastewater is also characterized with relatively moderate to high amount of salt, oil and total petroleum hydrocarbons (TPH). However, the bacteria which are growing in conventional activated sludge and MBR cannot survive at these strict conditions, therefore acclimation of the bacteria is of vital importance. The performance of the biological system, membrane permeability, the rate and extent of TPH biodegradability have been investigated under different sludge age and F/M ratios. The results obtained by gas chromatography analyses showed that the MBR system could be very effective in the removal of TPH from produced water and a significant improvement in the effluent quality was achieved. 相似文献
22.
Faster product development and increased competition in retail industries is resulting in shorter and shorter product life-cycles. This phenomenon is making it more difficult for a firm to accurately estimate random demand of such products and to plan their one-time order quantity accordingly. In this paper, we develop a model to assess the multiple effects of coordinated - i.e., joint - stocking and prior-sale discount decisions: (i) on the reduction of demand uncertainty; (ii) on maximization of the expected profit; and (iii) on the probability of achieving or exceeding it. We develop the joint optimal decisions that maximize the expected profit and discuss a procedure for computing the probability that the realized value of the (random) profit will exceed its maximum expected value. We present qualitative results on the varying effects of joint decisions on increasing the expected profit and the probability of achieving or exceeding it. We also describe a detailed numerical study examining the effects of varying parameter values on the percentage increase in expected profit with joint decision making. The paper concludes with extensions of the model that can deal with more general situations. 相似文献
23.
The photophysical and photochemical properties of the tetra- and octa-12-crown-4-substituted zinc (II) phthalocyanines are reported for the first time in the scope of this work. The new compounds have been characterized by elemental analysis, IR, 1H and 13C NMR spectroscopy, electronic spectroscopy and mass spectra. General trends are described for photodegradation, singlet oxygen and fluorescence quantum yields, and fluorescence lifetimes of these compounds in dimethylsulphoxide (DMSO). Photophysical and photochemical properties of phthalocyanine complexes are very useful for photodynamic therapy (PDT) applications. The effects of the substituents on the photophysical and photochemical parameters of the zinc (II) phthalocyanines (5, 6 and 7) are also reported. The singlet oxygen quantum yields (ΦΔ) ranged from 0.48 to 0.78 are indicating the potential of the complexes as photosensitizers in applications of PDT. The fluorescences of the substituted ZnPc complexes are effectively quenched by benzoquinone (BQ). 相似文献
24.
Sibel Silici Kemal Sarioglu Mahmut Dogan Kevser Karaman 《International Journal of Food Properties》2013,16(5):1126-1135
In this study, phenolic compounds of Rhododendron honey (also known as mad honey) samples collected from the Black Sea Region were identified using high performance liquid chromatography-diode array detector system. The major phenolic substances in Rhododendron honeys were found to be chlorogenic and coumaric acids with the amounts of 0.11–191.54 mg/kg and 0–82.83 mg/kg, respectively. Gallic and ferulic acids were detected in the most honey samples. Additionally, significant correlations were determined between the phenolic substances. The present study showed that Rhododendron honeys contained higher quantities of phenolic acids than flavonoids. Chlorogenic and coumaric acids were the dominant phenolic substances detected in honey samples. 相似文献
25.
Isil Oz Haluk Rahmi Topcuoglu Mahmut Kandemir Oguz Tosun 《Journal of Parallel and Distributed Computing》2012
Continuously reducing transistor sizes and aggressive low power operating modes employed by modern architectures tend to increase transient error rates. Concurrently, multicore machines are dominating the architectural spectrum today in various application domains. These two trends require a fresh look at resiliency of multithreaded applications against transient errors from a software perspective. In this paper, we propose and evaluate a new metric called the Thread Vulnerability Factor (TVF). A distinguishing characteristic of TVF is that its calculation for a given thread (which is typically one of the threads of a multithreaded application) does not depend on its code alone, but also on the codes of the threads that share resources and data with that thread. As a result, we decompose TVF of a thread into two complementary parts: local and remote. While the former captures the TVF induced by the code of the target thread, the latter represents the vulnerability impact of the threads that interact with the target thread. We quantify the local and remote TVF values for three architectural components (register file, ALUs, and caches) using a set of ten multithreaded applications from the Parsec and Splash-2 benchmark suites. Our experimental evaluation shows that TVF values tend to increase as the number of cores increases, which means the system becomes more vulnerable as the core count rises. We further discuss how TVF metric can be employed to explore performance–reliability tradeoffs in multicores. Reliability-based analysis of compiler optimizations and redundancy-based fault tolerance are also mentioned as potential usages of our TVF metric. 相似文献
26.
Multi-objective crashworthiness optimization of tapered thin-walled tubes with axisymmetric indentations 总被引:1,自引:0,他引:1
In this paper, the effects of tapering and introducing axisymmetric indentations on the crash performances of thin-walled tubes are investigated. The crash performances of the tubes are evaluated using two metrics: the crush force efficiency (CFE, the ratio of the average crushing load to the peak load), and the specific energy absorption (SEA, absorbed energy per unit mass). The optimum values of the number of the axisymmetric indentations, the radius of the indentations, the taper angle and the tube thickness are sought for maximum CFE and maximum SEA using surrogate based optimization. In addition, multi-objective optimization of the tubes is performed by maximizing a composite objective function that provides a compromise between CFE and SEA. The CFE and SEA values at the training points of surrogate models (metamodels) are computed using the finite element analysis code LS-DYNA. Polynomial response surfaces, radial basis functions, and Kriging are the different surrogate models used in this study. Surrogate based optimization of the tubes showed that the tubes with indentations have better crush performance than tubes without indentations. It is found that maximum CFE requires large number of indentations with high radius, small thickness, and medium taper angle, while maximum SEA requires small number of indentations with low radius, large thickness and small taper angle. It is also found that the globally most accurate surrogate model does not necessarily lead to the optimum. 相似文献
27.
Ceylan Zafer Mahmut Kus Gulsah Turkmen Haluk Dincalp Serafettin Demic Baha Kuban Yildirim Teoman Siddik Icli 《Solar Energy Materials & Solar Cells》2007,91(5):427-431
We have studied the influence of the spacer alkyl chain length of perylenemonoimide (PMI) dyes on the device performance in dye-sensitized solar cells (DSSCs). We observed that the dyes with longer and brunched alkyl chains exhibit higher efficiencies in DSSCs. In line with these statements we now report the highest efficiency obtained under standard conditions for a perylene imide derivative with PMI-DA1 that performs 300 mV open circuit voltage, 9.79 mA/cm2 short-circuit current and 1.61% overall conversion efficiency. 相似文献
28.
Postantibiotic effect of imipenem, alone and in combination with amikacin, on Pseudomonas aeruginosa
Imipenem and amikacin, alone and in combination, were investigated for their postantibiotic effect (PAE) on Pseudomonas aeruginosa. Four clinical strains of P. aeruginosa in the logarithmic phase of growth were exposed for 1 h to antibiotics, alone and in combination. Recovery periods of test cultures were evaluated after dilution using viable counting. Imipenem produced a PAE ranging from 0.7 to 1.55 h. Similar PAEs were induced by amikacin (ranging from 0.65 to 2 h). In combination, imipenem and amikacin produced as a final PAE (ranging from 1.6 to 2.65 h), a rough mathematical sum of the individual effects. The finding of this study may have important implications for the timing of doses during therapy with antimicrobial combinations. 相似文献
29.
smail Hakk Boyac Deniz Ba Fahriye Ceyda Dudak Ali Top u lbilge Saldaml Urartu
zgü r afak eker Candan Tamerler 《Food Biotechnology》2006,20(1):79-91
A statistical model approach called response surface methodology was used to describe the product and substrate inhibition effect on β-galactosidase enzyme during lactose hydrolysis. The effect of independent variables, namely the initial concentrations of lactose (73 - 146 mM), galactose (44 - 122 mM) and glucose (83 - 167 mM) on the reaction rate of β-galactosidase was evaluated. The enzymatic reaction rate was influenced by both combined and individual effects of all the substrate and products. Although, glucose acted as an activator at low lactose and low galactose concentrations, glucose caused the inhibition of β-galactosidase at higher concentrations of lactose and galactose. The effect of galactose concentration on β-galactosidase enzyme was in the direction of inhibition. At low lactose concentrations and high glucose concentrations, galactose concentration became more effective on the reaction rate. 相似文献
30.