Effects of the TiC and sintering process on the TiC-steel composite

In this paper, the composite of low alloy steel reinforced with TiC particles was prepared by conventional powder metallurgy process. The effects of the combined carbon content of TiC powder, sintering temperature and heating rate on the composite were studied. The results showed that the selected TiC powder has a combined carbon content of 17.91?wt-% and the optimal sintering process is heating from 600 to 1440°C at a rate of 1°C?min^?1 and holding for 1?h at 1440°C. The composite after heat treatment has excellent mechanical properties with density of 6.45?g?cm^?3, hardness of 68–69 HRC and TRS of 1763?MPa, respectively, and will be used as wear-resistant parts, assembly fixtures, moulds, etc.     

A neural network developed in a Foundation Fieldbus environment to calculate flow rates for compressible fluid

This paper proposes the development of an artificial neural network multilayer perceptron, implemented in a Foundation Fieldbus environment, to calculate the flow rate of natural gas by using an orifice plate in a closed pipe. The principal benefit of using neural networks lies in their low computational cost and simplicity of implementation, which allows just standard blocks to be used, making the technology independent of the Foundation Fieldbus system manufacturer. To perform the calculation, the proposed methodology relies on static pressure, temperature and differential pressure measurements, which are typically available in industrial plants. The developed methodology generates highly accurate results, and this approach can be implemented at a relatively low cost for Foundation Fieldbus system users.     

A weighted variable gain super-twisting observer for the estimation of kinetic rates in biological systems

The knowledge of kinetic reaction rates is important for monitoring and controlling biotechnological processes. However, the lack of on-line sensors for this purpose and the inherent problems with numerical differentiation make observers indispensable. In this work, we propose the use of a weighted variable gain super-twisting observer (WVGSTO), applicable to a class of second-order nonlinear systems that include a measurable weight on the unmeasured variable and the possibility of bounding the perturbations with measurable functions. This estimation method is illustrated with an academic example and then applied to a fed-batch bioprocess.     

Effect of Shear Rate Distribution on Particle Aggregation in a Stirred Vessel

The modeling of particle aggregation under a simple shear flow and the extension of the model to a stirred vessel is described. The model quantitatively demonstrates the change of the number of aggregates with time for each shear rate. This number increased with higher shear rate and, conversely, the aggregate size became small when raising the shear rate. This was because aggregates were broken by the stronger shear force. The number of aggregates for different impellers was determined. The shear rate was back‐calculated from the experimentally obtained aggregate size and the model equation. This shear rate was different from that estimated from the Metzner‐Otto method, consequently, some revisions of the Metzner‐Otto equation might be necessary for its application to particle aggregation.     

Influence of N2 introduction on structural and optical properties of V-doped ZnO thin films grown by low-temperature reactive RF magnetron sputtering

The influences of N₂ introduction to a sputtering gas on structural and optical properties of vanadium-doped ZnO (VZO) films, grown by using reactive RF magnetron sputtering on a quartz substrate at room temperature, were investigated. In the VZO films, V doping caused to form a large number of O vacancies (V_O) and degraded both the c-axis orientation and optical transmittance. While, on the contrary, the ZnO(002) diffraction intensity of 3.5-at.% VZO films increased adding N₂ with a partial pressure ratio (α_N2) >2% reaching a maximum at α_N2 =5%. The average optical transmittance (wavelengths: 450−800 nm) of the 3.5-at.% VZO films was also improved by the N₂ introduction and reached 74% at α_N2 =5%. As a result of the analyses of the chemical binding states of the incorporated N atoms via the Raman spectroscopy and XPS, it was confirmed that the O sites were substituted by the N atoms and the amount of incorporated N increased by the high V doping. From the above, the N₂ introduction was effective to suppress the V_O formation even in room-temperature-grown VZO films, so it enables to improve both the c-axis orientation and optical transmittance.     

A CO2 tracer-gas method for local air leakage detection and characterization

A method for local measurement of air leakage rate is presented that can be used to accurately and quickly assess leakage rates across a surface, such as around a valve or hatch in a pressurized gas tank or a window in a building. The method uses a small local enclosure with constant volume placed about a region on the structure under investigation (e.g., a window), which is depressurized and injected with a small concentration of carbon dioxide as a tracer gas. The time variation of the pressure and carbon dioxide concentration inside the enclosure are monitored and used to quantify the leakage flow rate as a function of pressure difference. This method uses a small enclosure with internal mixing so that a quasi-steady-state condition is quickly achieved. Because of the small size of the enclosure, advanced data processing techniques are necessary to reduce uncertainty in determination of the rate of change of the carbon dioxide concentration that arises from sensor variability. Results of a laboratory demonstration of the proposed leakage detection and characterization device are reported for the problem of leakage through a circular hole in a plate with prescribed pressure differences. Experimental results from the laboratory tests are found to be in excellent agreement with results of a numerical simulation of leakage flow through a hole, as well as predictions from a number of empirical equations for this problem found in the literature.     

水媒管式烟气换热器材料耐腐蚀性评价

水媒管式烟气换热器在工作中面临酸露的腐蚀,换热管材料需具备耐腐蚀性.模拟了水媒管式烟气换热器的腐蚀环境,采用自行设计的浸泡试验方法对8种候选材料的耐腐蚀性进行了比较,并采用扫描电镜对材料腐蚀后的表面形貌进行了研究.结果表明,ND 钢在高浓度硫酸中的耐腐蚀性优于碳钢;不锈钢254SMO在各种浓度硫酸溶液中的腐蚀速率均较低;聚四氟乙烯塑料（PTFE）具有优异的耐腐蚀性.     

Discharge characteristics of orifice spillway under oblique approach flow

Orifice type spillways are provided in the dam at lower level for facilitation in flushing of the sediment from the reservoir in addition to spilling the flood water. However, in most of the hydraulic structures, particularly in the earthen and rockfill dams, the spillway is not a part of the dam and it is provided on either of the banks of the river which results in oblique approach flow to the spillway that likely to affect the discharging capacity of the spillway. Presented in this paper is an experimental study for discharge characteristics of orifice type spillway under straight and oblique approach flow. Analysis of data indicates that discharge through the spillway decreases with increase of obliquity of the flow. The effect of the obliquity has been quantified and discharge equations for one, two and three simultaneous opening of the bays have been proposed.     

Experimental investigation of process parameters for roll-type linear chemical mechanical polishing (Roll-CMP) system

The fabrication processes for electronic components are now demanding a higher degree of planarity for integration and multistacking, with chemical mechanical polishing (CMP) processes replacing conventional etching or mechanical polishing owing to their ability to attain global planarization. As CMP has been applied to more and more fields, new types of CMP machines have been developed. This study introduces a novel roll-type linear CMP (Roll-CMP) process that uses a line-contact material removal mechanism to for the polish flexible substrates, and examines the effect of the process parameters on the material removal rate (MRR) and its nonuniformity (NU). The parameters affecting the Roll-CMP process include down force, roll speed, table feed rate, slurry flow rate, slurry temperature, and the table oscillation length. Increasing the down force, roll speed, slurry flow rate, and slurry temperature resulted in a high average MRR (MRR_avg). Further, the MRR_avg was found to decrease with an increase in the oscillation length because of the effect of the polishing area. A large down force, high roll speed, high table feed rate, and high slurry flow rate were effective for reducing the NU. These results will be helpful for understanding the newly developed Roll-CMP process.