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1.
The role of Ag in simultaneously catalyzing NO reduction and C3H6 oxidation was shown to be strongly dependent on the redox properties of its local environment. Under an atmosphere of 1,000 ppm
NO, 3,000 ppm C3H6, and 1% O2 and a GHSV of 30,000 h−1, a perovskite La0.88Ag0.12FeO3 prepared by reactive grinding is active giving a complete NO conversion and 92% C3H6 conversion at 500 °C. These values are much higher than the NO conversion of 55% and C3H6 conversion of 45% obtained over a 3 wt.% Ag/Al2O3 catalyst under the same conditions. Under an excess of oxygen (10% O2) a good SCR performance with a plateau of N2 yield above 97% over a wide temperature window of 350–500 °C along with C3H6 conversion of 90% at 500 °C was observed over Ag/Al2O3, while minor N2 yields (∼10% at 250–350 °C) and high C3H6 conversions (reaching ∼100% at 450 °C) were obtained over La0.88Ag0.12FeO3. Abundant molecular oxygen is desorbed from Ag substituted perovskite after 10% O2 adsorption as verified by O2- temperature programmed desorption (TPD). This reflects the strongly oxidative properties of La0.88Ag0.12FeO3, which lead to a satisfactory NO reduction at 1% O2 due to the ease of nitrate formation but to a significant C3H6 combustion above that value. The formation of nitrate species over the less oxidizing Ag/Al2O3 was accelerated under an excess of oxygen resulting in an excellent lean NO reduction behavior. The redox properties of silver
catalysts could be adjusted via mixing perovskite with alumina for an optimal elimination of both NO and C3H6 over the whole range of oxygen concentration between 0 to 10%. 相似文献
2.
John D.A. Abeysekera Houshang Shahnavaz 《International Journal of Industrial Ergonomics》1987,1(4):265-272
It is beyond doubt that high technology has elevated the standards of living of mankind. The modern technology created and developed to a great extent by Western or developed societies is now in great demand in Eastern and developing societies who are trying to leap-frog towards advancement. But unfortunately, in the transfer of technology, both the giver and the receiver seem to make many mistakes. A technology transferred without considering the ethnic variables in the societies and differences in the climates, has found to cause problems to the acquirer. Due to the basic human factor differences such as sizes of people, physical environment, physical capacities and organizational and cultural differences, a technology which is unadapted has found to be inappropriate, harmful, hazardous and unsuccessful. In the areas of health, working conditions, production and finance, undesirable effects have resulted through haphazard technology transfer, For a successful transfer, it is therefore stressed that technology has to be adapted or modified taking into consideration the technological, anthropological and socio-economic factors of the acquiring population. 相似文献
3.
Jan Westerink Gideon R. Hajer Mariëtte E. G. Kranendonk Henk S. Schipper Houshang Monajemi Eric Kalkhoven Frank L. J. Visseren 《Lipids》2014,49(3):247-254
We investigated the postprandial changes in plasma levels of adipocytokines in overweight patients with metabolic syndrome after an oral fat load. After an oral fat load and during a prolonged fast, blood was drawn at 0, 2, 3, 4 and 8 h for measurement of adiponectin, adipsin, cathepsin S, chemerin, hepatic growth factor, interferon‐γ‐inducible protein‐10, leptin, macrophage chemoattractant protein‐1, macrophage migration inhibitory factor, nerve growth factor, retinol binding protein‐4, resistin, serum amyloid A1, tissue inhibitor of metalloproteinase‐1 and thrombopoietin using a microbead‐based Luminex assay. Area under the curves (AUC) were calculated and compared. Plasma adiponectin levels were higher after an oral fat load compared to fasting at t = 2 h (950 ± 513 vs. ?1,881 ± 713 ng/ml) while the plasma levels for adipsin (?9 ± 5 vs. 16 ± 5 ng/ml), chemerin (?122 ± 35 vs. 13 ± 21 ng/ml), SAA‐1 (?391 ± 213 vs. 522 ± 173 ng/ml) and TPO (?335 ± 144 vs. 622 ± 216 ng/ml) were lower after an oral fat load compared to fasting. The baseline corrected AUC for IP‐10 was higher after fat load compared to fasting (median ?116 pg h/ml; IQR ?270 to 10 vs. ?21 pg h/ml; IQR ?136 to 418 (p = 0.047). In conclusion, in overweight male subjects with the metabolic syndrome, an oral fat load is accompanied with a modest anti‐inflammatory response of adipose tissue‐derived adipocytokines. 相似文献
4.
Houshang D. Alamdari Dominique Dub�� Pascal Tessier 《Metallurgical and Materials Transactions A》2013,44(1):388-394
The mechanism of heterogeneous grain refining of aluminum by ultrafine elemental boron particles was investigated. In order to facilitate the observation of the boron-aluminum interface, a boron filament was introduced in a melt at 1013 K (740 °C) containing different levels of Ti. The Al/B interface was studied using transmission electron microscopy and different phases were identified using the electron diffraction method. The experimental results showed that boron is dissolved in pure aluminum while its dissolution is inhibited in presence of titanium solute. A thin layer of TiB2 formed at the surface of boron thickens with residence time in the melt. The mechanisms by which aluminum is crystallized on boron are discussed. 相似文献
5.
Rayees Ahmad Shiekh Ismail Ab RahmanSam’an Malik Masudi Norhayati Luddin 《Ceramics International》2014
A nanohydroxyapatite–silica powder was synthesized using an ethanol based sol–gel technique. The synthesized powder was incorporated into commercial glass ionomer powder (Fuji II GC) and characterized using FTIR, 29Si CP/MAS NMR, EDX and XRD spectroscopy. 29Si CP/MAS NMR results showed the presence of higher degree of cross-linking of silyl species between silica and GIC, which makes the Nano-HA–Silica–GIC composite much stronger. High-resolution transmission electron microscopy (TEM) and scanning electron microscopy (TEM) was employed to investigate the morphology of the synthesized powder. Results revealed that higher content of nanosilica produced a denser and stronger GIC. Thus, the application of nanohydroxyapatite–silica–GIC with improved properties are envisioned to be of great clinical importance, especially in stress bearing areas. 相似文献
6.
Masume Masudi Rahimi Azam Astaneh Reza Poorghasemi 《Protection of Metals and Physical Chemistry of Surfaces》2019,55(2):363-370
Protection of Metals and Physical Chemistry of Surfaces - Corrosion protective coatings were developed on 1050 aluminum alloy through the sol–gel process using... 相似文献
7.
Amir Houshang Mahmoudi Mina Shahi Abbas Honarbakhsh Raouf 《International Communications in Heat and Mass Transfer》2011,38(1):119-127
The objective of this paper is to investigate the conjugated heat transfer in a thick walled cavity filled with copper-water nanofluid. The analysis uses a two-dimensional rectangular enclosure under conjugated convective-conductive heat transfer conditions and considers a range of Rayleigh numbers. The enclosure was subjected to a constant and uniform heat flux at the left thick wall generating a natural convection flow. The thicknesses of the other boundaries are assumed to be zero. The right wall is kept at a low constant temperature while the horizontal walls are assumed to be adiabatic. A moveable divider is located at the bottom wall of the cavity. The governing equations are derived based on the conceptual model in the Cartesian coordinate system. The study has been carried out for the Rayleigh number in the range of 105 ≤ Ra ≤ 108, and for the solid volume fraction at 0 ≤ ? ≤ 0.05. Results are presented in the form of streamlines, isotherms, average Nusselt number and input heat absorption by the nanofluid. The effects of solid volume fraction of nanofluids, the location of the divider and also the value of the ambient convective heat transfer coefficient on the hydrodynamic and thermal characteristics of flow have been analyzed. An increase in the average Nusselt number was found with the solid concentration for the whole range of Rayleigh number. In addition, results show that the position of the divider and the ambient convective heat transfer coefficient have a considerable effect on the heat transfer enhancement. 相似文献
8.
Maryam Haji Houshang Darabi 《The International Journal of Advanced Manufacturing Technology》2010,47(5-8):755-771
Inventory models use a set of parameters to establish their respected optimal policy. Such parameters are information items that have to be generated (obtained) and, therefore, there is a cost for obtaining them. Traditional inventory models simply ignore the existence of this cost and, therefore, the established optimal policies by these models may not be necessarily optimal in practice. In this paper, based on the requirements dictated by a real-world project, we analyze the impact of information update decisions for a specific class of inventory model (a single-period inventory model). The main difference between the presented model in this paper and newsboy problem is the presence of an inventory update decision and its effect on other inventory decisions. That is to decide when inventory-related information should be updated, how much should be ordered, and what is the maximum level of demand that can be promised to the customers. We formulate these decisions and develop mathematical methods to find the corresponding optimal policies. 相似文献
9.
This paper presents a novel application of recurrent neural network (RRN) to fault-tolerant control (FTC) of automated sequential manufacturing systems (ASMS) subject to sensor faults. Two RRNs are employed: the first one acts as an I/O relations recognizer and is able to detect faulty sensors and the latter is used as an inverse model of the AMSM to compute the desired control action in a faulty case according to nominal specifications. The learning process of these networks is carried out based on training data generated from the healthy manufacturing system controlled by a programmable logic controller (PLC). Design of the proposed fault-tolerant control system (FTCS) scheme is based on utilizing the two RNNs, a reconfigurable controller and a fault decision subsystem. The design procedure of the proposed FTCS is introduced. The proposed FTCS has been implemented and tested experimentally for a benchmark industrial ASMS subject to single or multiple faulty sensors. Experimental results show the effectiveness of the procedure for a real simple plant. In addition, the results prove these features of the proposed FTCS: (a) effectively improving the faulty control system behaviors, (b) accomplishing its proper functionality in handling single and multiple sensor faults, (c) identifying the sensor faults, and (d) being advantageous in reducing the complexity of the hardware redundancy. 相似文献
10.
Ardavan H Ardavan A Singleton J Fasel J Schmidt A 《Journal of the Optical Society of America. A, Optics, image science, and vision》2008,25(3):543-557
We calculate the gradient of the radiation field generated by a polarization current with a superluminally rotating distribution pattern and show that the absolute value of this gradient increases as R(7/2) with distance R, within the sharply focused subbeams that constitute the overall radiation beam from such a source. In addition to supporting the earlier finding that the azimuthal and polar widths of these subbeams become narrower (as R(-3) and R(-1), respectively) with distance from the source, this result implies that the boundary contribution to the solution of the wave equation governing the radiation field does not always vanish in the limit where the boundary tends to infinity (as is commonly assumed in textbooks and the published literature). While the boundary contribution to the retarded solution for the potential can always be rendered equal to zero by means of a gauge transformation that preserves the Lorenz condition, the boundary contribution to the retarded solution of the wave equation for the field may be neglected only if it diminishes with distance faster than the contribution of the source density. In the case of a rotating superluminal source, however, the boundary term in the retarded solution for the field is by a factor of the order of R(1/2)larger than the source term of this solution, in the limit where the boundary tends to infinity. This result explains why an argument based on the solution of the wave equation governing the field in which the boundary term is neglected [such as that presented by Hannay, J. Opt. Soc. A 23, 1530 (2006)] misses the nonspherical decay of the field that is generated by a rotating superluminal source. The only way one can calculate the free-space radiation field of an accelerated superluminal source is via the retarded solution for the potential. Our findings have implications also for the observations of the pulsar emission: The more distant a pulsar, the narrower and brighter its giant pulses should be. 相似文献