印度东部钛磁铁矿的氧化行为和相分析

钛磁铁矿是一种复杂的共生矿石,含有钛铁矿、磁铁矿、铁铝尖晶石和镁铁铝尖晶石等矿物。对从印度东部采集到的钛磁铁矿石进行XRD、WDXRF、SEM和M？ssbauer谱分析。在氧气气氛下,通过TG-DTA分析对矿石的氧化行为进行研究。随后,在氧气和空气气氛下,将样品在不同温度下（873-1473 K）保温不同时间,进行等温氧化实验。观察到在较低的温度下钛铁矿相转变为赤铁矿、氧化钛,而在较高的温度下转变为钛酸亚铁相。将氧化后的矿样与焦炭混合压制成圆柱形球团,在1473 K下进行直接还原,成功地实现了将磁铁矿铁转变为氧化铁和二氧化钛的相变。     

Biobutanol: science,engineering, and economics

Among several liquid alternative fuels, biobutanol has shown great promise because of its very similar properties to gasoline. This review provides an overview of research activities in acetone–butanol–ethanol (ABE) fermentation over the past two and a half decades. We have addressed seven important facets of ABE fermentation, viz. biochemistry, microbial cultures, alternative substrates, solvent recovery, fermentation mode and reactor designs, mathematical modeling, and economics. Development of mutant strains having higher yield, selectivity and tolerance to inhibition, and search for cheap alternative substrates for fermentation are most important thrust areas in biobutanol production. New and efficient processes have been developed for in situ removal and recovery of the ABE solvents. Several rigorous kinetic and physiological models for fermentation have been formulated, which form useful tool for optimization of the process. These research activities have been reviewed in this paper. Finally, we have summarized studies on the economic viability of large‐scale ABE fermentation processes employing various process designs, substrates, and microbial cultures. With the use of new strains, inexpensive substrates, and superior reactor designs, economic potential of ABE fermentation has been found to be highly attractive. Research efforts in science, engineering, and economics of ABE fermentation have brought biobutanol close to commercialization as liquid alternate fuel. Copyright © 2011 John Wiley & Sons, Ltd.     

Effect of unit-cells of the frequency selective surface as superstrate on the directivity of rectangular microstrip antenna

In this paper, the relationship between the number of unit-cells used in the design of a frequency selective surface (FSS) and its expected directivity is established. The relationship between the number of FSS unit-cells and the directivity is based on the planer microstrip patch array antenna design concept where the unit-cell is treated as the superstrate illuminated by the source. To validate the proposed technique, the analytical value of the directivity has been compared with that of ray-tracing method. The directivity of antenna is calculated for two different planar array configurations at 600 GHz. The results of numerical analysis are compared to that of the full-wave electromagnetic simulator CST Microwave Studio and results are comparable. Further, the directivity computed by this proposed technique has also been compared with that of the reported in literatures.     

Experimental study of paddy drying in a vortex chamber

The intensification of interfacial mass, heat, and momentum transfer makes vortex chambers potentially interesting for the efficient drying of paddy, allowing shorter drying times and/or more compact equipment. The presence of a shell introduces particular challenges. Intraparticle diffusion limitations are strong and may reduce the advantage from intensified interfacial mass and heat transfer and the efficiency of air usage. Furthermore, high shear and normal stresses in the fast rotating particle bed may cause damage to the paddy shell, posing problems for transport and storage. With these specific aspects in mind, the use of vortex chambers for paddy drying is experimentally evaluated.     

Providing Dynamic Visual Information for Collaborative Tasks: Experiments With Automatic Camera Control

One possibility presented by novel communication technologies is the ability for remotely located experts to provide guidance to others who are performing difficult technical tasks in the real world, such as medical procedures or engine repair. In these scenarios, video views and other visual information seem likely to be useful in the ongoing negotiation of shared understanding, or common ground, but actual results with experimental systems have been mixed. One difficulty in designing these systems is achieving a balance between close-up shots that allow for discussion of detail and wide shots that allow for orientation or establishing a mutual point of focus in a larger space. Achieving this balance can be difficult without disorienting or overloading task participants. In this article we present results from two experiments involving three automated camera control systems for remote repair tasks. Results show that a system providing both detailed and overview information was superior to systems providing only one or the other in terms of performance but that some participants preferred the detail-only system.     

Self generating square/triangular wave and pulse width modulator using a single MO-CCCDTA

A self-generating square/triangular wave and pulse width modulator (PWM) using multiple output current controlled current differencing transconductance amplifier (MO-CCCDTA) is presented. To obtain all the three functions simultaneously from the same topology, the MO-CCCDTA is modified a little bit. The characterisation of the modified MO-CCCDTA structure shows that the parasitic resistances at input terminals (n and p) can be varied via bias current. The maximum useful frequency range is found to be 635 MHz, which is higher than the available literature. The waveform generator and PWM circuit use only one MO-CCCDTA, one grounded capacitor and no resistor; hence suitable for IC implementation. The duty cycle of proposed pulse width modulation can be tuned by bias current of MO-CCCDTA over a wide range. The performances of the proposed block and its applications (square/triangular/PWM) are verified by PSPICE simulation using TSMC 0.35 µm technology. The power consumption is about 1.12 mW. To verify experimentally, a prototype of MO-CCCDTA has been made using commercially available ICs (AD844AN and CA3080) on printed circuit board. The simulation and experimental results verify theoretical proposition well. Monte carlo simulation is carried out, which proves satisfactory performance of the proposed circuit against mismatches. The performance of the proposed circuit is also verified through pre-layout and post-layout simulation results. The required chip area is only 22.415 × 14.6 µm².     

Acrylic-ester-polyol based novel two-component polyurethane clear coat: Evaluation of performance characteristics

In the current study, a combination of acrylic polyol (AP) and ester polyol (EP) were synthesized and reacted at variable ratios with hexamethylene diisocyanates and isophorone diisocyanates to prepare a transparent two-component polyurethane (PU) coating formulation. The formations of the polyol system, isocyanate system, and the PU systems were confirmed by ¹H nuclear magnetic resonance and Fourier-transform infrared spectroscopy. Transparency of the coatings was examined using haze, and gloss measurement, which showed acrylic-ester-polyurethane (aePU-5 and aePU-6) have 91.5% and 91.8% transparency and gloss of 90.3 and 90.7 GU respectively. The thermal properties like T_g and the thermal stability of the coatings were verified using differential scanning calorimetry, and thermogravimetric analysis respectively which was found to increase with increasing EP content and decreasing AP content which may be ascribed to improved compatibility of copolymers, and homogeneity in PU along with enhanced crosslinking density. The degree of adhesion of coating with the substrate was validated from lap-shear, and cross-cut tape test which showed improved performance at AP:EP ratio of 60:40. The coatings were found to exhibit resistance toward pencil hardness with aePU-5 and aePU-6 having the optimum resistance of 9H. The surface morphology and topography were observed under scanning electron microscopy, and atomic force microscopy, respectively. The outcome confirms the higher smoothness of the surfaces subjected to the increase in EP content. The PU system with 40 wt% AP content and 60 wt% EP designated as aePU-5 was found to exhibit optimum performance.     

Automated quantized inference for probabilistic programs with AQUA

Innovations in Systems and Software Engineering - We present AQUA, a new probabilistic inference algorithm that operates on probabilistic programs with continuous posterior distributions. AQUA...     

Dietary and bioactive properties of the berries and leaves from the underutilized Hippophae salicifolia D. Don grown in Northeast India

Food Science and Biotechnology - The physico-chemical, polyphenols, antioxidant and antibacterial properties of berries and mixture of male and female leaves of Hippophae salicifolia were...