Differentiate performance of eight filter media in vertical flow constructed wetland: Removal of organic matter, nitrogen and phosphorus

A comparative study was conducted to reveal the differentiate effects of eight different filter media including gravel, zeolites, anthracite, shale, vermiculite, ceramic filter media, blast furnace steel slag and round ceramsite. The study mainly related to the eight different filter media's removal performances of organic matter, nitrogen and phosphorus in the vertical flow constructed wetland simulated system, which treating wastewater at hydraulic loading rate of 1000-2500 mm/d. The results indicated that the removal effects were closely related to the physical and chemical properties of medium materials. Anthracite-filled system had the highest removal rate for the total organic carbon (TOC), up to 70%, and the removal rates of other systems ranged from 20% to 30%. As for the five-day biochemical oxygen demand (BOD5), anthracite-filled and steel slag-filled systems had the highest removal rates, also up to 70%, as well as other systems all exceeded 50%. At the same time, for the total nitrogen (TN) and NH4(+)-N, the zeolites-filled and ceramic-filled systems had the best performances with the removal rates of more than 70%, the other way round, the removal rates of other systems were only about 20%. The distinguishable effects were also observed in removal performances of total phosphorus (TP) and total dissoluble phosphorus (TDP). The removal rates of TP and TDP in steel slag-filled systems were more than 90%, a much higher value, followed by that of the anthracite-filled system, more than 60%, but those of other systems being the less. Our study provided a potential mechanism to optimize the filter media design for the vertical flow constructed wetlands.

A role of monitoring to reduce the uncertainty in the performance of pile foundations

In typical conventional foundation design, the inherent variability of soil properties, model uncertainty and construction variability are not modeled explicitly. A main drawback of this is that the effect of each variability on the probability of an unfavorable event cannot be evaluated quantitatively. In this paper, a method to evaluate the uncertainty-reduction effect on the performance of a vertically-loaded pile foundation by monitoring the pile performance (such as pile load testing or placing sensors in piles) is proposed. The effectiveness of the proposed method is examined based on the investigation of a 120-pile foundation placed on three different ground profiles. The computed results show the capability of evaluating the uncertainty-reduction effect on the performance of a pile foundation by monitoring. © 2014 Taylor & Francis Group, London.

Single mode performance of a single mode injected locked quantum dot laser

An injection locked QD laser is demonstrated to provide single longitudinal mode operation with a 40dB SMSR and an improvement in RIN peak from 1.3-2.3GHz. Alpha factor is measured to be 0.8. © 2005 Optical Society of America.

Single mode performance of a single mode injected locked quantum dot laser

An injection locked QD laser is demonstrated to provide single longitudinal mode operation with a 40dB SMSR and an improvement in RIN peak from 1.3-2.3GHz. Alpha factor is measured to be 0.8. © 2005 Optical Society of America.

Use of microbial community to evaluate performance of a wetland system in treating Pb/Zn mine drainage

The performance of a wetland system in treating lead (Pb)/zinc (Zn) mine drainage was evaluated by using the polyurethane foam unit (PFU) microbial community (method), which has been adopted by China as a standardized procedure for monitoring water quality. The wetland system consisted of four cells with three dominant plants: Typha latifolia, Phragmites australis and Paspalum distichum. Physicochemical characteristics [pH, EC, content of total suspended solid (TSS) and metals (Pb, Zn, Cd, and Cu)] and PFU microbial community in water samples had been investigated from seven sampling sites. The results indicated that the concentrations of Pb, Zn, Cd, Cu, and TSS in the mine drainage were gradually reduced from the inlet to the outlet of the wetland system and 99%, 98%, 75%, 83%, and 68% of these metals and TSS respectively, had been reduced in concentration after the drainage passed through the wetland system. A total of 105 protozoan species were identified, the number of protozoa species and the diversity index (DI) gradually increased, while the heterotrophic index (HI) gradually decreased from the inlet to the outlet of the wetland system. The results indicated that DI, HI, and total number species of protozoa could be used as biological indicators indicating the improvement of water quality.

Viability and performance of demountable composite connectors

Material production, and associated carbon emissions, could be reduced by reusing products instead of landfilling or recycling them. Steel beams are well suited to reuse, but are difficult to reuse when connected compositely to concrete slabs using welded studs. A demountable connection would allow composite performance but also permit reuse of both components at end-of-life. Three composite beams, of 2 m, 10 m and 5 m length, are constructed using M20 bolts as demountable shear connectors. The beams are tested in three-, six- and four-point bending, respectively. The former two are loaded to service, unloaded, demounted and reassembled; all three are tested to failure. The results show that all three have higher strengths than predicted using Eurocode 4. The longer specimens have performance similar to previously published comparable welded-connector composite beam results. This suggests that demountable composite beams can be safely used and practically reused, thus reducing carbon emissions. © 2013 Elsevier B.V. All rights reserved.

Performance of hybrid buffer Poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) layers doped with plasmonic silver nanoparticles

We compare the performance of a typical hole transport layer for organic photovoltaics (OPVs), Poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS) thin film with a series of PEDOT:PSS layers doped with silver (Ag) nanoparticles (NPs) of various size distributions. These hybrid layers have attracted great attention as buffer layers in plasmonic OPVs, although there is no report up to date on their isolated performance. In the present study we prepared a series of PEDOT:PSS layers sandwiched between indium tin oxide (ITO) and gold (Au) electrodes. Ag NPs were deposited on top of the ITO by electron beam evaporation followed by spin coating of PEDOT:PSS. Electrical characterization performed in the dark showed linear resistive behavior for all the samples; lower resistance was observed for the hybrid ones. It was found that the resistivity of the samples decreases with increasing the particle's size. A substantial increase of the electric field between the ITO and the Au electrodes was seen through the formation of current paths through the Ag NPs. A striking observation is the slight increase in the slope of the current density versus voltage curves when measured under illumination for the case of the plasmonic layers, indicating that changes in the electric field in the vicinity of the NP due to plasmonic excitation is a non-vanishing factor. © 2014 Published by Elsevier B.V. All rights reserved.

Effects of feeding rate on growth performance of white sturgeon (Acipenser transmontanus) larvae

Four 1-week trials were conducted to determine the effects of feeding rates on growth performance and body proximate composition of white sturgeon larvae during each of the first 4 weeks after initiation of feeding. Feeding rates (% body weight day(-1)) were 10, 20, 30, 40, 50, and 60 for trial I; 5, 10, 15, 20, 25, and 30 for trial II; and 2.5, 5.0, 7.5, 10.5, 12.5, and 15.0 for trials III and TV Four tanks with 200 larvae each were randomly assigned to each of the six feeding rates. Average initial body weights of the larvae were 49, 94, 180, and 366 mg, respectively, for trials I-IV. The larvae were kept at 19-20 degreesC in circular tanks and fed continuously one of two commercial salmonid soft-moist feeds using automatic feeders. Proximate composition (%) of the feeds for trials I-III and IV were 13.9 and 14.9 moisture, 52.5 and 50.0 crude protein, 10.3 and 12.9 crude fat, and 8.1 and 8.7 ash, respectively. Except mortality in trial I, gain per food fed in trial III, and body ash in all trials, growth performance and body composition were significantly (P<0.05) affected by all feeding rates. Broken line analysis on specific growth rates indicated the optimum feeding rates of white sturgeon larvae to be 26%, 13%, 11%, and 6% body weight day-respectively, for weeks 1, 2, 3, and 4 after initiation of feeding. (C) 2003 Elsevier Science B.V. All rights reserved.

Growth performance of juvenile white sturgeon as affected by feeding regimen

Juvenile (mean +/- SE, 8.6 +/- 0.1 g) white sturgeon Acipenser transmontanus were fed for 8 weeks under one of six feeding regimens: continuously 24 h/d (C24); continuously 12.8 h/d during the day (C12/D), continuously 12.8 h/d at night (C12/N), 6 meals/d (M6), 4 meals/d (M4), and 2 meals/d (M2). Specific growth rate, feed efficiency, and body lipid content were significantly (P < 0.05) affected by the feeding regimen. These variables were highest in the C24 group and lowest in the M2 group; fish in the M6 group showed the second best performance. Specific growth rate and feed efficiency in terms of wet weight in the M6 groups were not significantly different from those in the C24 groups, but specific growth rate in terms of energy and energy retention efficiency were significantly lower. Feeding regimen had no effect on condition factor, hepatosomatic index, coefficient of variation in final body weight, and protein and ash contents. There was no significant difference in these indexes between 12.8-h/d continuous feeding by day or by night. It was concluded that continuous feeding for 24 h/d was the optimum feeding regimen for juvenile white sturgeon.

Theoretical design and performance of InxGa1-xN two-junction solar cells

The efficiencies of InxGa1-xN two-junction solar cells are calculated with various bandgap combinations of subcells under AM1.5 global, AM1.5 direct and AM0 spectra. The influence of top-cell thickness on efficiency has been studied and the performance of InxGa1-xN cells for the maximum light concentration of various spectra has been evaluated. Under one-sun irradiance, the optimum efficiency is 35.1% for the AM1.5 global spectrum, with a bandgap combination of top/bottom cells as 1.74 eV/1.15 eV. And the limiting efficiency is 40.9% for the highest light concentration of the AM1.5 global spectrum, with the top/bottom cell bandgap as 1.72 eV/1.12 eV.

Effect of p-GaN layer thickness on the performance of p-i-n structure GaN ultraviolet photodetectors

We investigated the influence of thickness of p-GaN layer on the performance of p-i-n structure GaN ultraviolet photodetector. Through the simulation calculation, it was found that both the quantum efficiency and dark current of device decrease when employing thicker p-GaN layer, while both the quantum efficiency and dark current increase with decreasing thickness of p-GaN layer. It is suggested that the Schottky contact junction between the metal and p-GaN may be responsible for the incompatible effect. We has to make a suitable choice of the thickness of p-GaN in the device design according to the application requirement.

Improvement of the performance of GaN-based LEDs grown on sapphire substrates patterned by wet and ICP etching

Sapphire substrates patterned by a selective chemical wet and an inductively coupled plasma (ICP) etching technique was proposed to improve the performance of GaN-based light-emitting diodes (LEDs). GaN-based LEDs were fabricated on sapphire substrates through metal organic chemical vapor deposition (MOCVD). The LEDs fabricated on the patterned substrates exhibit improved device performance compared with the conventional LED fabricated on planar substrates when growth and device fabricating conditions were the same. The light output powers of the LEDs fabricated on wet-patterned and ICP-patterned substrates were about 37% and 17% higher than that of LEDs on planar substrates at an injection current of 20 mA, respectively. The enhancement is attributable to the combination of the improvement of GaN-based epilayers quality and the improvement of the light extraction efficiency. (c) 2008 Elsevier Ltd. All rights reserved.

Research on the influence of fabrication parameters on the performance of buried ion-exchanged glass waveguides using the variational method

The variational method is proposed to analyze the influence of the fabrication parameters on the performance of buried K+-Na+ ion-exchanged Er3+-Yb3+ ions co-doped glass waveguide. The unknown parameters of the Hermite-Gaussian functions as the trial field distribution are determined based on the scalar variational principle. It is demonstrated that the results calculated in this paper agree with those measured in the experiment. The mode dimensions, the effective refractive index, and the overlap factor as the functions of the fabrication parameters are investigated. These results of the variational analysis are useful for the design and optimization of Er3+-Yb3+ ions co-doped waveguides.