Effect of Iron Ore Pellet Size on its Properties and Microstructure

The properties of the pellets and their microstructure mainly depend on the raw material mix proportion, raw material chemical composition and the physicochemical conditions like the temperature and oxygen partial pressure within the induration machine. The pelletising plant products are in the size range of 8 to 16 mm. With increasing pellet size, the sintering intensity, thermo‐chemical conditions and formation of different phases vary across its cross section. The time required for varies reactions within the pellet is directly proportional to the pellet size. Because of differences in pellet size, the reduction and oxidation process takes place under different conditions resulting in different phases and microstructures. In this work, detailed studies were carried out on pellets of different size (8 to 16 mm) produced from a 4.2 Mtpa pellet plant for their physical, metallurgical and microstructural properties. It was observed that the pellets in the size range of +8 to ‐12 mm showed good strength and lower RDI. It was observed that the amount of hematite, magnetite, porosity, pore density, pore size and slag phase play a significant role on pellet strength and RDI.     

An innovative semianalytical technique for ceramic evaluation at microwave frequencies

We have developed an innovative semianalytical technique for various substrate material characterization. The developed technique is a measurement procedure and data-reduction formulation that takes into consideration the radiation loss in a resonant structure, allowing for a more effective means of dielectric- and conductor-loss determination for a microstrip ring resonator and its substrate material. We separate dielectric and conductor loss precisely, evaluate the contribution of each term in the overall loss performance, and analytically predict the error in their respective predicted value.     

Comparative Study of Different Adaptive Window Protocols

We study an Adaptive Window Protocol (AWP) with general increase and decrease profiles in the presence of window dependent random losses. We derive a steady-state Kolmogorov equation, and then obtain its solution in analytic form for particular TCP versions proposed for high speed networks, such as Scalable TCP and HighSpeed TCP. We also relate window evolution under an AWP to workload process in queueing systems; this observation gives us a way to compare various AWP protocols.     

评价淬火介质换热特性的Grossmann法与集中热容法的比较

研究了用于估算纳米流体、盐水溶液和某洗涤剂基试验介质淬火烈度的Grossmann法和集中热容（ LHC）法的适用性,评价了探头截面厚度对不同淬火介质换热系数的影响。借助于计算机分析了304不锈钢探头在淬火过程中的冷却曲线,并分别采用Grossmann法和LHC法对所测得的冷却曲线进行了换热系数的估算。研究表明,采用矱10 mm不锈钢探头的LHC法适用于淬火烈度小于20 m-1介质的表征。虽然Grossmann法是基于平均换热系数这一假设的,但仍能应用于具有不同淬火烈度介质之间的评定。 Grossmann法能更敏感地反映探头截面厚度对换热的影响。     

Atomic layer deposition of HfO2 thin films and nanolayered HfO2–Al2O3–Nb2O5 dielectrics

Smooth, 4–6-nm thick hafnium oxide films were grown by atomic layer deposition from HfI₄ or HfCl₄ and H₂O on SiO₂/Si(1 0 0) substrates at 300 °C. Non-uniform films were obtained on hydrogen-terminated Si(1 0 0). The stoichiometry of the films corresponded to that of HfO₂. The films contained small amounts of residual chlorine and iodine. The films deposited on SiO₂/Si(1 0 0) were amorphous, but crystallized upon annealing at 1000 °C. In order to decrease the conductivity, the HfO₂ films were mixed with Al₂O₃, and to increase the capacitance, the films were mixed with Nb₂O₅. The capacitance–voltage curves of the Hf–Al–O mixture films showed hysteresis. The capacitance–voltage curves of HfO₂ films and mixtures of Hf–Al–Nb–O were hysteresis free.     

Molecular Epidemiological Study of Pyrazinamide-Resistance in Clinical Isolates of Mycobacterium tuberculosis from South India

Pyrazinamide (PZA) has been in use for almost 50 years as a first-line drug for short-course chemotherapy against Mycobacterium tuberculosis. In this study, PCR mediated automated DNA sequencing is used to check the prevalence of PZA resistance among treatment failure cases of pulmonary tuberculosis. Out of 50 clinical isolates examined, 39 had mutations in the pncA gene that encodes Pyrazinamidase, an enzyme required to activate PZA. Of these, 31 (79.5%) were localized to three regions of pncA. We found two isolates with hitherto unreported mutation at amino acid 26 (Ala→Gly) of pncA.     

Casting/mold thermal contact heat transfer during solidification of Al-Cu-Si alloy (LM 21) plates in thick and thin molds

Heat flow at the casting/mold interface was assessed and studied during solidification of Al-Cu-Si (LM 21) alloy in preheated cast iron molds of two different thicknesses, coated with graphite and alumina based dressings. The casting and the mold were instrumented with thermocouples connected to a computer controlled temperature data acquisition system. The thermal history at nodal locations in the mold and casting obtained during experimentation was used to estimate the heat flux by solving the one-dimensional inverse heat conduction problem. The cooling rate and solidification time were measured using the computer-aided cooling curve analysis data. The estimated heat flux transients showed a peak due to the formation of a stable solid shell, which has a higher thermal conductivity compared with the liquid metal in contact with the mold wall prior to the occurrence of the peak. The high values of heat flux transients obtained with thin molds were attributed to mold distortion due to thermal stresses. For thin molds, assumption of Newtonian heating yielded reliable interfacial heat transfer coefficients as compared with one-dimensional inverse modeling. The time of occurrence of peak heat flux increased with a decrease in the mold wall thickness and increase in the casting thickness.     

TETRA-BUTYL-MALONAMIDE AND TETRA-ISOBUTYL MALONAMIDE AS EXTRACTANTS FOR URANIUM(VI) AND PLUTONIUM(IV)

ABSTRACT

Two new symmetrical diamides, namely straight-chain alkyl substituted neutral tetra-butyl-malonamide(TBMA) and sterlcally hindered branched-chain alkyl substituted tetra-isobutyl malonamide(TIBMA) were synthesised, characterised and used for the extraction of U(VI) and Pu(IV) from nitric acid media into n-dodecane. Both the cations were found to be extracted as their disolvates. Interestingly TBMA extracted more efficiently than TIBMA but afforded poor selectivity for Pu/U separation. The thermodynamic parameters involved in the extraction, determined by the temperature variation method, indicated the reactions in all cases to be enthalpy favoured. Entropy was found to be counteracting the extraction of U(VI) and favouring the extraction of Pu(IV). The recovery of diamides from the loaded actinides could be easily accomplished by using dilute oxalic acid or dilute U(IV) as the strippant for Pu(IV) and using dilute Na₂C0₃ as that for U(VI).     

P-NoC: Performance Evaluation and Design Space Exploration of NoCs for Chip Multiprocessor Architecture Using FPGA

Wireless Personal Communications - The network-on-chip (NoC) has emerged as an efficient and scalable communication fabric for chip multiprocessors (CMPs) and multiprocessor system on chips...     

Investigation on Slicing Behavior of Single Crystal Silicon Wafer in AWJM and Influence of Micro Dimple Textured Surface for Solar Applications

Silicon - The current investigation focuses on the slicing characteristics of silicon, a hard and brittle solid that is very difficult to cut, with abrasive water jet machining (AWJM) process by...