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排序方式: 共有124条查询结果,搜索用时 15 毫秒
121.
Adamantios D. Skordilis 《Bioresource technology》1992,40(3):241-244
Combustion of cotton gin residues was studied in the furnace of a continuous-operation, modern lime kiln. During its first period of operation, the plant experienced some problems; corrosion of the refractory bricks, difficulty in controlling the temperature at the main burner, a hard mass of lime building up inside the kiln and around the main burner. However, in spite of the problems successful production of lime was finally achieved. Measurements show that the use of cotton gin residues as a combustible material does not create any significant changes either in the quality of the lime or in the environment. 相似文献
122.
Roshana T. Maske Atul N. Yerpude Rupesh S. Wandhare Sanjay J. Dhoble 《Luminescence》2023,38(10):1814-1824
The CaAlBO4:RE (RE = Dy3+, Eu3+, Sm3+) phosphor were prepared via combustion synthesis and studied by X-ray diffraction (XRD), Fourier-transform infrared (FTIR) analysis, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), photoluminescence (PL) spectra and CIE coordinates. The phase formation of the obtained phosphor was analyzed by XRD and the result was confirmed by standard PDF Card No. 1539083. XRD data successfully indicated pure phase of CaAlBO4 phosphor. The crystal structure of CaAlBO4 phosphor is orthorhombic with space group Ccc2 (37). The SEM image of CaAlBO4 phosphor reveals an agglomerated morphology and non-uniform particle size. The EDS image provides evidence of the elements present and the chemical makeup of the materials. Under the 350 nm excitation, the emission spectrum of Dy3+ activated CaAlBO4 phosphor consists of two main groups of characteristic peaks located at 484 and 577 nm which are ascribed to 4F9/2 → 6H15/2 and 4F9/2 → 6H13/2 transition of Dy3+ respectively. The PL emission spectra of CaAlBO4:Eu3+ phosphor shows characteristics bands observed around 591 and 613 nm, which corresponds to 5D0 → 7F1 and 5D0 → 7F2 transition of Eu3+ respectively, upon 395 nm excitation wavelength. The emission spectra of Sm3+ activated CaAlBO4 phosphor shows three characteristic bands observed at 565, 601 and 648 nm which emits yellow, orange and red color. The prominent emission peak at the wavelength 601 nm, which is attributed to 4G5/2 → 6H7/2 transition, displays an orange emission. The CIE color coordinates of CaAlBO4:RE (RE = Dy3+, Eu3+, Sm3+) phosphor are calculated to be (0.631, 0.368), (0.674, 0.325) and (0.073, 0.185). As per the obtained results, CaAlBO4:RE (RE = Dy3+, Eu3+, Sm3+) phosphor may be applicable in eco-friendly lightning technology. 相似文献
123.
Background, Aim and Scope The objective of this life cycle assessment (LCA) study is to develop LCA models for energy systems in order to assess the
potential environmental impacts that might result from meeting energy demands in buildings. The scope of the study includes
LCA models of the average electricity generation mix in the USA, a natural gas combined cycle (NGCC) power plant, a solid
oxide fuel cell (SOFC) cogeneration system; a microturbine (MT) cogeneration system; an internal combustion engine (ICE) cogeneration
system; and a gas boiler.
Methods LCA is used to model energy systems and obtain the life cycle environmental indicators that might result when these systems
are used to generate a unit energy output. The intended use of the LCA analysis is to investigate the operational characteristics
of these systems while considering their potential environmental impacts to improve building design using a mixed integer
linear programming (MILP) optimization model.
Results The environmental impact categories chosen to assess the performance of the energy systems are global warming potential (GWP),
acidification potential (AP), tropospheric ozone precursor potential (TOPP), and primary energy consumption (PE). These factors
are obtained for the average electricity generation mix, the NGCC, the gas boiler, as well as for the cogeneration systems
at different part load operation. The contribution of the major emissions to the emission factors is discussed.
Discussion The analysis of the life cycle impact categories indicates that the electrical to thermal energy production ratio has a direct
influence on the value of the life cycle PE consumption factors. Energy systems with high electrical to thermal ratios (such
as the SOFC cogeneration systems and the NGCC power plant) have low PE consumption factors, whereas those with low electrical
to thermal ratios (such as the MT cogeneration system) have high PE consumption factors. In the case of GWP, the values of
the life cycle GWP obtained from the energy systems do not only depend on the efficiencies of the systems but also on the
origins of emissions contributing to GWP. When evaluating the life cycle AP and TOPP, the types of fuel as well as the combustion
characteristics of the energy systems are the main factors that influence the values of AP and TOPP.
Conclusions An LCA study is performed to eraluate the life cycle emission factors of energy systems that can be used to meet the energy
demand of buildings. Cogeneration systems produce utilizable thermal energy when used to meet a certain electrical demand
which can make them an attractive alternative to conventional systems. The life cycle GWP, AP, TOPP and PE consumption factors
are obtained for utility systems as well as cogeneration systems at different part load operation levels for the production
of one kWh of energy output.
Recommendations and Perspectives Although the emission factors vary for the different energy systems, they are not the only factors that influence the selection
of the optimal system for building operations. The total efficiencies of the system play a significant part in the selection
of the desirable technology. Other factors, such as the demand characteristics of a particular building, influence the selection
of energy systems.
The emission factors obtained from this LCA study are used as coefficients of decision variables in the formulation of an
MILP to optimize the selection of energy systems based on environmental criteria by taking into consideration the system efficiencies,
emission characteristics, part load operation, and building energy demands. Therefore, the emission factors should not be
regarded as the only criteria for choosing the technology that could result in lower environmental impacts, but rather one
of several factors that determine the selection of the optimum energy system.
ESS-Submission Editor: Arpad Horvath (horvath@ce.berkeley.edu) 相似文献
124.
Michael D. Lebowitz 《Aerobiologia》1991,7(1):10-16
Summary The scientific study of indoor air quality has been a topic for research in the last two decades; in the late 70's it became
an issue of general public perception. The public perceptions have been such tremendous stimuli because they involve aspects
of health and welfare (comfort and economics). Various biomedical studies were performed to evaluate adverse biological effects
associated with ambient and occupational pollutants. However, it became obvious that humans were exposed more, on a temporal
basis, to their normal indoor environments than they were either in the workplace or outside. Concern with biological contaminants
was always an issue, but rarely examined indoors until recently. Biological responses to the indoor environment will be discussed
in this paper. 相似文献