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81.
《Applied Thermal Engineering》2003,23(3):285-293
Food consumption around the world produces large amounts of waste vegetable oils and fats that, in many world regions, are disposed of in harmful ways. Consequently, this study intended to investigate the feasibility of utilizing this renewable and low cost fuel raw material as a diesel fuel replacement in small-scale applications such as in residential heating boilers. Specifically, the study examined the aspects of combustion performance and emissions of the ethyl ester of used palm oil (biodiesel) relative to the baseline diesel fuel in a water-cooled furnace. The combustion efficiency, ηc, and exhaust temperature, Texh, as well as the common pollutants and emissions were tested over a wide range of air/fuel ratio ranging from very lean to very rich (10:1–20:1). All tests were conducted at two different energy inputs for both fuels. The findings showed that, at the lower energy rate used, biodiesel burned more efficiently with higher combustion efficiency and exhaust temperature of, respectively, 66% and 600 °C compared to 56% and 560 °C for the diesel fuel. At the higher energy input, biodiesel combustion performance deteriorated and was inferior to diesel fuel due to its high viscosity, density and low volatility. As for emissions, biodiesel emitted less pollutants at both energy levels over the whole range of A/F ratio considered. 相似文献
82.
《Journal of power sources》2002,105(1):26-34
This work is focused at optimizing an ethanol reforming process over a Ni/Cu catalyst to produce a hydrogen rich stream in order to feed a solid polymer fuel cell (SPFC). The effect of the reaction temperature, H2O/EtOH and O2/EtOH molar ratios of the feed to the reformer was studied under diluted conditions in order to maximize the hydrogen content and the CO2/COx molar ratio at the outlet of the ethanol reformer. Based on the experimental results, a detailed kinetic scheme of the ethanol reforming was discussed as a function of the temperature, special attention was paid to the role of oxygen in the reaction selectivity and coke formation. Moreover, the coke nature was evaluated by transmission electron microscopy (TEM) and TPO and TPH experiments. The tests carried out at on-board reformer conditions allowed a hydrogen rich mixture (33%) in the outlet reformer flow that can be even increased by water gas sift reactions downstream. The high hydrogen content of the flow to the fuel cell together with the stability of the Ni/Cu catalyst, fully demonstrated by long time runs, can be considered of high interest for SPFC applications. 相似文献
83.
《Knowledge》2007,20(3):300-309
Algorithmic composition of musical pieces is one of the most popular areas of computer aided music research. Various attempts have been made successfully in the area of music composition. Artificial intelligence methods have been extensively applied in this area. Representation of musical pieces in a computer-understandable form plays an important role in computer aided music research.This paper presents a neural network-based knowledge representation schema for representing notes, melodies, and time in first species counterpoint pieces. A musical note is composed of pitch and duration in this representation schema. The proposed representation technique was tested using the back-propagation algorithm to generate two-voice counterpoint pieces. 相似文献
84.
Pollinators play an important role in agriculture, food security, and ecosystems. They are facing serious population declines in the US as well as around the world, leading to concerns regarding natural fertilization, reduced crop yields, and economic threats to farmers and/or related agricultural businesses. Governments and non-governmental organizations have introduced policies and programs to conserve pollinators and increase public awareness of pollinator decline. This study focuses on online and social media content about pollinators as a proxy for public interest, measured by volume and sentiment of media. Additionally, we evaluate potential links between public interest and the reaction of markets of pollinator-derived products, namely honey. Volume and sentiment of online media surrounding pollinators was quantified for the years 2017 – 2021. Search results show mentions mostly driven by pleasant mentions of bees, honey, honeybee costumes, and butterfly migration rather than topics related to the pollination-related threats, causes, polices, and/or programs. Wholesale and retail prices of honey have been less variable than mentions over time, suggesting no apparent relationship between volume of online media activities surrounding pollinators (including bees) and honey prices. The low volume of mentions about threats towards pollinators may suggest a low level of public awareness of the topic and yield concerns for the effectiveness of polices for protecting pollinators and/or concern for economics of beekeepers, even with the active legislations of the US federal and states government for promoting pollinators health. 相似文献
85.
《International Journal of Hydrogen Energy》2023,48(72):27978-27991
The introduction of other combustible gases to methane could change accident consequences. This work aimed to experimentally compare the effects of blended fuels (C2H6, C2H4, CO, and H2 mix in different proportions) on the explosion pressure behavior of methane and blended fuels in air. The explosion pressure properties of the mixtures were tested. Principal component analysis was employed, and multiple regression models were developed to predict the influences of principal components on the maximum explosion pressure of CH4. In addition, the software was used to analyze and compare the sensitivity analysis. For the fuel-lean CH4-air mixture(φ = 0.72), the results demonstrated that the value of Pmax and (dP/dt)max of the mixed gases increased, as the volume fraction of the blended fuels increased. The effects of other gases followed the order C2H6>C2H4>H2>CO. For stoichiometric concentrations (φ = 1), the order of the influence degree was H2>CO > C2H6>C2H4, and the value of Pmax and (dP/dt)max of the mixed gases tended to decrease slightly. As the volume fraction of the blended fuels was increased to 2%, the Pmax and (dP/dt)max of CH4 showed a decreasing trend for the fuel-rich CH4-air mixture. The effects of blended fuels on the equivalence ratio of φ = 1.1 followed the order C2H4>H2>CO > C2H6. The sensitivity variation analysis and normalized sensitivity variation analysis indicated that the chain branching reaction 2CH3(+M)<=>C2H6(+M) was the most sensitive reaction under various conditions. However, it was not very susceptible to changes in the blended fuel ratio. Most reactions were susceptible to changes in the blended fuel ratio. The 10 most sensitive reactions were generally much more susceptible to changes in the blended fuel ratio in the 2% blended fuels than they were in the 0.4% blended fuels. 相似文献
86.
《International Journal of Hydrogen Energy》2023,48(74):28882-28890
The sluggish kinetics of urea oxidation reaction (UOR) critically restrict the prevalence of direct urea fuel cell (DUFC), utilizing electrolyte containing urea/urine. In this work, the copper and nickel-based composite oxides are prepared by meticulously controlling the galvanic reaction of copper ion to metallic nickel and the high-temperature oxidation process. Based on a systematic electrochemical characterization of the catalyst, the as-fabricated nano-architectures are optimized toward UOR performance, showing a low potential of 1.39 V vs. RHE to drive 100 mA cm−2 in alkaline solution. The button-like DUFCs configuration of as-developed catalysts exhibits a maximum power density of 1.19 mW cm−2. Furthermore, the DUFCs assembled with bio-urine, including men, dogs, cats, and rats as electrolytes without further purification, show a similar voltage. These findings open up a direction to convert bio-waste into treasure. 相似文献
87.
《International Journal of Hydrogen Energy》2023,48(79):30832-30843
La–Mg–Ni-based hydrogen storage alloys showed good application prospects owing to their high hydrogen storage capacity. However, the poor cycling stability was a key problem. In order to improve the cycling stability, low cost YFe0.85 master alloy was used as raw material to prepare La–Mg–Ni-based La0.8-xYxMg0.2Ni3-0.85xFe0.85x (x = 0.50, 0.55, 0.60) hydrogen storage alloys by powder sintering method. The alloys were mainly composed of PuNi3 phase and MgCu4Sn phase. With the increase of Y and Fe, the cell parameters of PuNi3 phase decreased. Lower mismatch coefficient promoted the cycling stability. As the case of x = 0.60, the capacity retention rate rose up to 95.45%. Aside from the cycling stability, appropriate substitution content contributed to higher capacity and satisfactory kinetics. As the case of x = 0.55, the hydrogen storage capacity reached 1.529 wt%, and hydriding time for the x = 0.60 alloy shrank to 76.7% of that for alloys without Y and Fe at 303 K. 相似文献
88.
《International Journal of Hydrogen Energy》2019,44(57):30185-30195
Nowadays, energy shortage is one of the major problems in the world. Photocatalytic hydrogen production is a new type of energy technology with good application prospect. As a new type of photocatalytic semiconductor material, g-C3N4 has attracted much attention as a photocatalyst. By ultrasonic treatment of a mixed solution of g-C3N4 and bovine serum albumin, followed by adding a certain amount of silver nitrate solution and then directly hydrothermal treatment, a special dandelion-like g-C3N4/Ag (D-g-C3N4/Ag) was prepared. The scanning electronic microscopy, transmission electronic microscopy, X-ray diffraction, Fourier transform infrared, fluorescence and physicochemical adsorption methods were used to characterize the morphology and structure of D-g-C3N4/Ag. In addition, the photocatalytic H2 production of D-g-C3N4/Ag with different Ag loadings or in different sacrificial agents and different pH conditions were investigated. The results indicated that when triethanolamine was used as sacrificial agent, photocatalytic hydrogen efficiency was the best, and the rate of photocatalytic hydrogen production reached 862 μmol g−1 h− 1 as the Ag loading was 4%. 相似文献
89.
This article presents the first spectroscopic data describing the processes responsible for the temporary blue-green coloration that forms during the hydration of various materials containing Ground Granulated Blast-furnace Slag (GGBS) under anoxic conditions. UV-visible-near infrared Diffuse Reflectance (DR) spectra demonstrate a striking similarity of the coloring center forming during the curing of a broad range of GGBS-bearing materials (pure GGBS with different compositions, mix Portland cement/GGBS (30/70), concrete and mortar). All spectra are similar to those of polysulfide complexes contained in the interlayer spacing of a synthetic green-colored hydrated calcium aluminate phase (AFm). This “greening effect” demonstrates a progressive oxidation of sulfide-based compounds initially contained in these materials during curing of GGBS bearing materials. 相似文献
90.
TiO2 incorporated Eco-blocks have been successfully developed and widely used worldwide. However, under real-life service, various environmental factors will significantly influence their photocatalytic performance. In this study, the photocatalytic NOx conversion of two sets of concrete surface layers (intermixed and spray-coated with nano-TiO2) was investigated and compared under different NO flow rates, initial NO concentrations, ultraviolet (UV) light intensities, light sources and relative humidity (RH) conditions. In addition, the abrasion resistance of all the samples was examined. The results showed that the TiO2 spray-coated samples (SP) outperformed the 5% TiO2-intermixed samples with respect to NOx removal efficiency under all the investigated conditions. Both the NO flow rate and initial NO concentration had a positive impact on the NOx removal rate but a negative influence on the NOx removal ratio. An increase in photocatalytic NOx removal rate and NOx removal ratio was attained by an increase in UV light intensity. Whereas, the NOx removal efficiency first increased, reached a peak, and then decreased with increasing RH. It was found that the most effective light source for photocatalytic NOx removal was UV-A, but Solar light (SL) irradiation resulted in a comparable NOx removal. Moreover, the SP samples harboured robust resistance to abrading. The findings from this study would provide the basis for effectively evaluating the NOx removal performance of concrete surface layers under atmospheric conditions. 相似文献