Environmental concerns and limited amount of petroleum fuels have caused interests in the development of alternative fuels for internal combustion (IC) engines. As an alternative, biodegradable, and renewable fuel, ethanol is receiving increasing attention. Therefore, in this study, influence of injection timing on the exhaust emission of a single cylinder, four stroke, direct injection, naturally aspirated diesel engine has been experimentally investigated using ethanol blended diesel fuel from 0% to 15% with an increment of 5%. The engine has an original injection timing 27° CA BTDC. The tests were performed at five different injection timings (21°, 24°, 27°, 30°, and 33° CA BTDC) by changing the thickness of advance shim. The experimental test results showed that NOx and CO2 emissions increased as CO and HC emissions decreased with increasing amount of ethanol in the fuel mixture. When compared to the results of original injection timing, at the retarded injection timings (21° and 24° CA BTDC), NOx and CO2 emissions increased, and unburned HC and CO emissions decreased for all test conditions. On the other hand, with the advanced injection timings (30° and 33° CA BTDC), HC and CO emissions diminished, and NOx and CO2 emissions boosted for all test conditions. 相似文献
Pyrite cinders, which are the waste products of sulphuric acid manufacturing plants, contain hazardous heavy metals with potential environmental risks for disposal. In this study, the potential use of pyrite cinders (PyCs) as iron source in the production of Portland cement clinker was demonstrated at the industrial scale. The chemical and mineralogical analyses of the PyC sample used in this study have revealed that it is essentially a suitable raw material for use as iron source since it contains >87% Fe2O3 mainly in the form of hematite (Fe2O3) and magnetite (Fe3O4). The samples of the clinkers produced from PyC in the industrial scale trial operation of 6 months were tested for the conformity of their chemical composition and the physico-mechanical performance of the resultant cement products. The data were compared with the clinker products of the iron ore, which is used as the raw material for the production Portland cement clinker in the plant. The chemical compositions of all the clinker products of PyC appeared to conform to those of the iron ore clinker, and hence, a Portland cement clinker. The mechanical performance of the mortars prepared from the PyC clinker was found to be consistent with those of the industrial cements e.g. CEM I type cements. It can be inferred from the leachability tests (TCLP and SPLP) that PyC could be a potential source of heavy metal pollution while the mortar samples obtained from the PyC clinkers present no environmental problems. These findings suggest that the waste pyrite cinders can be readily used as iron source for the production of Portland cement. The availability of PyC in large quantities at low cost provides further significant benefits for the management/environmental practices of these wastes and for the reduction of mining and processing costs of cement raw materials. 相似文献
The synthesis of boron undoped and doped indium stabilized bismuth oxide nanoceramic powders via the polymeric precursor technique were described. The physical properties of the precursor polymer solutions (pH, surface tension, viscosity and conductivity) were measured. 相似文献
An alternative bioceramic bone graft was synthesized through the sol-gel method by substituting strontium carbonate—SrCO3 and Silver—Ag into Ca(NO3)2·4H2O, KOH, NaNO3, P2O5, and urea compounds. Morphological properties of the fabricated grafts were characterized by X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), and Scanning Electron Microscopy (SEM). Mechanical properties were determined via the hardness and compression tests. Furthermore, the cell viability of fabricated biografts was also determined via cytotoxicity tests using the MTS (cell proliferation assay). FTIR, EDS, and XRD analyses indicated that SrCO3- and Ag-substituted hydroxyapatite (Sr/Ag/HA) biograft fabrications were achieved. SEM images of the biografts showed that a low-porous structure was formed with grains bonded through sintering. SEM images also revealed that the powder bonding increased due to the decrease in pore sizes when the amount of SrCO3 was increased. From the mechanical tests, it was obtained that, the strength and hardness increased with increased SrCO3 rates. Through the cytotoxicity tests, it was shown that the cell viability rate increased due to the presence of SrCO3 and no toxic effects were observed through the newly synthesized biografts. 相似文献
Some hydrological quantities such as the rainfall intensity, which is defined as the quotient of the rainfall depth to the rainfall duration, are based on functions of random variables. At this point, the probability distribution of that quantity arises. Then one may take this distribution into account for the exact statistical inference without referring to a simulation study. There are a lot of works on the exact distributions of functions of random variables in the literature. One case is for the Pareto distributed random variables. Pareto distribution and its upper truncated version have many applications in hydrological modelling. In this paper, the exact distributions of the product, sum and quotient of two independently distributed upper truncated Pareto random variables are obtained. Although the probability density functions of the product and quotient are obtained in elementary mathematical functions, that for the sum is obtained in terms of a special function. Some characteristics of these functions such as moments and percentiles can be easily obtained. The distributions of the quotient and the sum are applied on a rainfall data set from hydraulic efficiency research of green roofs. The parameters are estimated by the method of maximum likelihood. The theoretical results of this paper may also be useful to other practitioners of the upper truncated Pareto distribution.