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排序方式: 共有722条查询结果,搜索用时 15 毫秒
491.
Prashant Shirodkar Yusuf Mehta Aaron Nolan Khyati Sonpal Alan Norton Chris Tomlinson Eric Dubois Patrick Sullivan Robert Sauber 《Construction and Building Materials》2011,25(1):150-155
The objective of this paper is to provide a methodology for determining the degree of partial blending in high RAP mixtures. When RAP is mixed with virgin aggregates and virgin binder, partial blending of RAP binder occurs in the hot mix asphalt. Agencies limit the amount of RAP because the degree of blending between the RAP and the virgin materials is not known. The methodology provides a systematic approach for determining the degree of partial blending in the RAP mixture. The ability to accurately determine the degree of partial blending will help in determining the virgin binder content to be added in the mixture. The degree of partial blending measured from this procedure for 25% RAP by weight of aggregates with PG 70-28 and 35% RAP by weight of aggregates with PG 58-28 are 70% and 96% respectively. 相似文献
492.
493.
Tamer Uyar Ioan Cianga Luminita Cianga Flemming Besenbacher Yusuf Yagci 《Materials Letters》2009,63(18-19):1638-1641
Bundled and self-aligned fibers were obtained by electrospinning blends of polystyrene (PS) and poly(methyl methacrylate) (PMMA) with a hairy-rod polyphenylene-g-polystyrene/poly(a-caprolactone) (PP-g-PS/PCL) copolymer. The self-alignment and bundling characteristics of these electrospun fibers were ascribed to the unique molecular architecture of the conjugated polymer, PP-g-PS/PCL, and its interactions with the solvent and the polymer matrixes used for the electrospinning. The self-alignment and bundling was found to be much more pronounced for PP-g-PS/PCL-PS blend when compared to PP-g-PS/PCL-PMMA blend. Furthermore we found that the degree of self-alignment of the fiber bundles was enhanced by increasing the amount of PP-g-PS/PCL in the blends but the alignment completely disappeared when the solvent dimethylformamide was changed to chloroform. 相似文献
494.
Model predictions of metal speciation in freshwaters compared to measurements by in situ techniques 总被引:1,自引:0,他引:1
Unsworth ER Warnken KW Zhang H Davison W Black F Buffle J Cao J Cleven R Galceran J Gunkel P Kalis E Kistler D Van Leeuwen HP Martin M Noël S Nur Y Odzak N Puy J Van Riemsdijk W Sigg L Temminghoff E Tercier-Waeber ML Toepperwien S Town RM Weng L Xue H 《Environmental science & technology》2006,40(6):1942-1949
Measurements of trace metal species in situ in a softwater river, a hardwater lake, and a hardwater stream were compared to the equilibrium distribution of species calculated using two models, WHAM 6, incorporating humic ion binding model VI and visual MINTEQ incorporating NICA-Donnan. Diffusive gradients in thin films (DGT) and voltammetry at a gel integrated microelectrode (GIME) were used to estimate dynamic species that are both labile and mobile. The Donnan membrane technique (DMT) and hollow fiber permeation liquid membrane (HFPLM) were used to measure free ion activities. Predictions of dominant metal species using the two models agreed reasonably well, even when colloidal oxide components were considered. Concentrations derived using GIME were generally lower than those from DGT, consistent with calculations of the lability criteria that take into account the smaller time window available forthe fluxto GIME. Model predictions of free ion activities generally did not agree with measurements, highlighting the need for further work and difficulties in obtaining appropriate input data. 相似文献
495.
In this study, electrochemical oxidation of phenol was carried out in a parallel plate reactor using ruthenium mixed metal oxide electrode. The effects of initial pH, temperature, supporting electrolyte concentration, current density, flow rate and initial phenol concentration on the removal efficiency were investigated. Model wastewater prepared with distilled water and phenol, was recirculated to the electrochemical reactor by a peristaltic pump. Sodium sulfate was used as supporting electrolyte. The Microtox bioassay was also used to measure the toxicity of the model wastewater during the study. As a result of the study, removal efficiency of 99.7% and 88.9% were achieved for the initial phenol concentration of 200 mg/L and chemical oxygen demand (COD) of 480 mg/L, respectively. In the same study, specific energy consumption of 1.88 k Wh/g phenol removed and, mass transfer coefficient of 8.62 x 10(-6)m/s were reached at the current density of 15 mA/cm(2). Electrochemical oxygen demand (EOD), which can be defined as the amount of electrochemically formed oxygen used for the oxidation of organic pollutants, was 2.13 g O(2)/g phenol. Electrochemical oxidation of petroleum refinery wastewater was also studied at the optimum experimental conditions obtained. Phenol removal of 94.5% and COD removal of 70.1% were reached at the current density of 20 mA/cm(2) for the petroleum refinery wastewater. 相似文献
496.
Issam Srour Mohamed-Asem Abdul-Malak Mona Itani Amal Bakshan Yusuf Sidani 《Engineering Management Journal; EMJ》2013,25(3):85-100
Abstract:When faced with the decision of selecting an advanced degree, many engineers opt for management related studies rather than further specialization in a technical field. This article attempts to highlight the reasons behind such choices, and explores the role that a Master's degree in Engineering Management (MEM) plays in career planning and progression. A survey of 58 MEM graduates, who completed their studies at a prominent university in Lebanon between 1992 and 2009, reveals that the majority of the respondents follow a linear career path, rapidly paving the way towards managerial positions. For most of the respondents, earning a graduate degree in engineering management played a primary role in, or at least contributed to, making this shift. The article concludes with a diagram sketching the possible career paths for MEM graduates. By showing the number of years spent at different career stages, the diagram serves as a career-planning tool for MEM graduates, engineers, managers, and researchers. 相似文献
497.
The effects of quenching air temperature, quenching air speed and winding speed in the melt spinning process of poly(ethylene terephthalate) fibres with a titre of 147 dtex and 96 filaments on dye uptake were investigated. The ranges used for quenching air temperature, quenching air speed and winding speed were 17–27 °C, 0.3–0.7 m/s and 2600–3800 m/min, respectively. Specimens were dyed and their colour strengths (K/S values) were measured using a spectrophotometer. The results were statistically analysed. 相似文献
498.
Factors influencing luxury uptake of phosphorus by microalgae in waste stabilization ponds 总被引:2,自引:0,他引:2
Phosphorus removal in waste stabilization ponds (WSP) is highly variable, but the reasons for this are not well understood. Luxury uptake of phosphorus by microalgae has been studied in natural systems such as lakes but not under the conditions found in WSP. This work reports on the effects of phosphate concentration, light intensity, and temperature on luxury uptake of phosphorus by WSP microalgae in continuous culture bioreactors. Increasing temperature had a statistically significant "positive effect" on intracellular acid-insoluble polyphosphate concentration. It is likely that elevated temperature increased the rate of polyphosphate accumulation, but because the biomass was not starved of phosphate, the stored acid-insoluble polyphosphate was not utilized. Increasing light intensity had no effect on acid-insoluble polyphosphate but had a "negative effect" on the acid-soluble polyphosphate. A possible explanation for this is that the faster growth rate at high light intensity results in this form of polyphosphate being utilized by the cells for synthesis of cellular constituents at a rate that exceeds replenishment. The variability in the phosphorus content of the microalgal biomass shows that with this new understanding ofthe luxury uptake mechanism there is the potential to optimize WSP for biological phosphorus removal. 相似文献
499.
Yusuf S. Luk W. Sloman M. Dulay N. Lupu E.C. Brown G. 《Very Large Scale Integration (VLSI) Systems, IEEE Transactions on》2008,16(1):57-65
This paper describes a reconfigurable architecture based on field-programmable gate-array (FPGA) technology for monitoring and analyzing network traffic at increasingly high network data rates. Our approach maps the performance-critical tasks of packet classification and flow monitoring into reconfigurable hardware, such that multiple flows can be processed in parallel. We explore the scalability of our system, showing that it can support flows at multi-gigabit rate; this is faster than most software-based solutions where acceptable data rates are typically no more than 100 million bits per second. 相似文献
500.
Elcin Cakal Sarac Leila Haghighi Poudeh Jamal Seyyed Monfared Zanjani Zeki Semih Pehlivan Fevzi Çakmak Cebeci Ismail Aydin Yusuf Menceloglu Burcu Saner Okan 《应用聚合物科学杂志》2019,136(47):48347
In this study, long carbon nanofibers (CNFs) were grown on graphene nanoplatelets (GNPs) by chemical vapor deposition (CVD) technique to develop three-dimensional (3D) bicomponent nanostructures. The structure and properties of graphene before and after CVD process were investigated in details. X-ray photoelectron analysis depicted the formation of Fe-C bonds by the deposition of carbon atoms on the catalyst surface of Fe2O3. This hybrid additive was firstly used as a reinforcing agent in melt compounding to fabricate PA6.6-based nanocomposites with enhanced mechanical and thermal properties. Both GNP and CNF-GNP have enough surface oxygen functional groups to improve the interfacial interactions with polyamide matrix and thus provide good wettability. Also, both neat GNP and its bicomponent additive with CNF also acted as a nucleating agent and allowed the crystal growth in nanocomposite structure. Homogeneous dispersion of nanoparticles was achieved by using thermokinetic mixer during compounding by applying high shear rates. Mechanical results showed that 23 and 34% improvement in flexural and tensile modulus values, respectively, was attained by the addition of 0.5 wt % CNF-GNP hybrid additive. The heat distortion temperature and Vicat softening temperature of the resulting PA6.6 nanocomposites were improved compared to neat PA6.6 material indicating performance enhancement at higher service temperature conditions. CNF was successfully grown on Fe-loaded GNP by CVD method and this hybrid additive was compounded with PA6.6 by melt-mixing process. Mechanical results showed that 34% improvement in tensile modulus value was attained by the addition of 0.5 wt % CNF-GNP hybrid additive because it acted as a nucleating agent and allowed the crystal growth in the nanocomposite structure. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48347. 相似文献