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971.
972.
Suresh Kumar Anil Kumar Anupam Shukla G. Rohini Devi A.K. Gupta 《Journal of the European Ceramic Society》2009,29(13):2849-2855
Carbon fiber reinforced silicon carbide (C–SiC) composites are promising materials for a severe thermo-erosive environment. 3D-stitched C–SiC composites were fabricated using liquid silicon infiltration. The infiltration was carried out at 1450–1650 °C for 10–120 min in vacuum. Coefficient of thermal expansion (CTE) of the composites was determined in in-plane and through-thickness directions in the temperature range from room temperature to 1050 °C. The in-plane CTE varies in the range (0.5–2) × 10?6/°C, while that in the through-thickness direction, it varies in the range (1.5–4) × 10?6/°C. The effect of siliconization conditions is higher in the through-thickness direction than in the in-plane direction. The CTE values are lower than the values reported for chemical vapor impregnation based 3D C–SiC composites. An extensive microstructure study was also carried out to understand the thermal expansion behavior of the composites. It was found out that CTE behavior is closely related to the composition of the composite which in turn depends upon siliconization conditions. The best conditions were 1650 °C and 120 min. 相似文献
973.
Suresh V. Garimella James E. Simpson 《Nanoscale and Microscale Thermophysical Engineering》2013,17(3):173-188
The solidification processing of metal matrix composites is investigated using a modified enthalpy method that can account for the presence of the discontinuous reinforcing phase. The propagation of the solid liquid interface is tracked through the complicated, microscale domain formed by the fibers. Conduction in the matrix as well as in the dispersed phase is considered. The fixed-grid, single-domain computational approach presented is much more efficient than a previous three-domain approach reported in the literature. Results obtained from the simulations compare well with those in the literature in terms of the shape of the interface obtained and its movement in the presence of low- and high-conductivity fibers. Important extensions to the work are outlined, primary among these being the inclusion of the effects of melt convection and solutal gradients. 相似文献
974.
Abstract This paper presents design, development, and testing of a resonant sensor to measure mass in the range of 0–10 grams. The main feature of the proposed sensor is the microcontroller based closed loop electronics. The advantage of using the microcontroller is that the method can be easily extended for any range of measurand. 相似文献
975.
A hierarchical methodology for the design of manufacturing cells is proposed, which includes labour-grouping considerations in addition to partmachine grouping. It is empirically driven and designed for an interactive decision environment, with an emphasis on fast execution times. The method synthesizes the capabilities of neural network methods for rapid clustering of large partmachine data sets, with multi-objective optimization capabilities of mathematical programming. The procedure includes three phases. In Phase I, part families and associated machine types are identified through neural network methods. Phase II involves a prioritization of part families identified, along with adjustments to certain load-related parameters. Phase III involves interactive goal programming for regrouping machines and labour into cells. In machine grouping, factors such as capacity constraints, cell size restrictions, minimization of load imbalances, minimization of intercell movements of parts, minimization of new machines to be purchased, provision of flexibility, etc. are considered. In labour grouping, the functionally specialized labour pools are partitioned and regrouped into cells. Factors such as minimization of hiring and cross-training costs, ensuring balanced loads for workers, minimization of intercell movements of workers, providing adequate levels of labour flexibility, etc. are considered in a pragmatic manner. 相似文献
976.
S. Jayakumar P.V. Ananthapadmanabhan T.K. Thiyagarajan K. Perumal S.C. Mishra G. Suresh L.T. Su A.I.Y. Tok 《Materials Chemistry and Physics》2013
Pure zirconium oxide powders with particle size 2–33 nm are synthesized by reactive plasma processing. Transmission electron microscopy investigation of these particles revealed size dependent behavior for their phase stabilization. The monoclinic phase is found to be stable when particle size is ≥20 nm; Tetragonal is found to be stabilized in the range of 7–20 nm and as the particle size decreases to 6 nm and less, the cubic phase is stabilized. 相似文献
977.
Diez-Silva M Dao M Han J Lim CT Suresh S 《MRS bulletin / Materials Research Society》2010,35(5):382-388
The biconcave shape and corresponding deformability of the human red blood cell (RBC) is an essential feature of its biological function. This feature of RBCs can be critically affected by genetic or acquired pathological conditions. In this review, we highlight new dynamic in vitro assays that explore various hereditary blood disorders and parasitic infectious diseases that cause disruption of RBC morphology and mechanics. In particular, recent advances in high-throughput microfluidic devices make it possible to sort/identify healthy and pathological human RBCs with different mechanobiological characteristics. 相似文献
978.
979.
980.
Feasibility of formation of stoichiometric precursors of either M2 (TiO)2(C2O4)5 4H2O (M = La and Nd) or coprecipitated hydroxides of M(OH)3+TiO(OH)2 was investigated by two solution routes at different pH values. Composition of precipitates obtained at pH = 7.0 by coprecipitation method starting from La or Nd nitrates and potassium titanyl oxalate corresponded to a physical mixture of La or Nd(C2O4)3 9.5H2O and TiO(OH)27·H2O which on thermal decomposition did not yield phase pure M2Ti2O7. However, precipitation from La or Nd nitrates and titanium tertrachloride by urea hydrolysis yielded homogeneous mixture of hydroxides of La or Nd and Ti, which on pyrolysis at 950°C yielded phase pure La2Ti2O7 and Nd2Ti2O7. Use of potassium titanyl oxalate as precursor for Ti, led to selective precipitation of La or Nd oxalate even at pH as low as 0.1 leading to sequential precipitation of La or Nd oxalate followed by Ti hydroxide at pH = 3.0. The resultant precipitate on pyrolysis underwent typical solid-state reaction. 相似文献