Austenite Reconstruction Elucidates Prior Grain Size Dependence of Toughness in a Low Alloy Steel

Texture and grain size distribution of the austenite phase at high temperature have distinct effects on the subsequent transformed microstructure and mechanical properties of steel alloys at room temperature. Measurement of austenite at high temperature is not, however, a trivial task especially if orientation maps are desired. Therefore, a technique for determining austenite texture and grain size that was present at high temperature is highly desirable. In this work, we review several pipe samples intended for use as well casing with large variations in toughness and martensitic microstructures at room temperature. Microstructural analysis of the martensite structures could not easily explain these differences due to how martensite forms from austenite. An algorithm was developed to reconstruct the parent austenite at high temperature from martensite microstructure at room temperature. This technique successfully reconstructed orientation maps for the prior austenite in these samples, demonstrating differences in texture, grain orientation spread, and austenite grain size that could account for the differences in mechanical properties.     

A simple and portable multi-colour light emitting diode based photocolourimeter for the analysis of mixtures of five common food dyes

A simple and cheap spectrophotometric method for the simultaneous determination of Tartrazine, Quinoline Yellow, Sunset Yellow, Carmoisine and Brilliant Blue in commercial food products with the aid of a portable double beam photocolourimeter are described. The method is based on the difference of the absorptivity ratios at maximum absorbances of two compounds or three compounds. The proposed device uses red–green–blue light-emitting diode as light source and light dependent resistor as detector. A programmable microcontroller sequentially turns the emitters on, receives the signals followed by calculating the absorbance and displaying it on a liquid–crystal display. The photometer is capable of performing absorbance measurements in a single wavelength as well as in three wavelengths sequentially, allows its application in simultaneous analysis of binary and ternary mixtures based on the differences of absorbance ratios in two and/or three wavelengths. The method was validated against a standard HPLC method and the results obtained were in a good agreement with those of HPLC method.     

Theoretical and practical investigations of copper ion selective electrode with polymeric membrane based on N,N′-(2,2-dimethylpropane-1,3-diyl)-bis(dihydroxyacetophenone)

A novel ion-selective poly(vinyl chloride) (PVC) membrane sensor for Cu²⁺ ions based on N,N′-(2,2-dimethylpropane-1,3-diyl)-bis(dihydroxyacetophenone) (NDHA) as a new ionophore was prepared and studied. The best performance was observed for the membrane composition, including 30:65:1:4 (wt%) = PVC:DBP:KTpClPB:NDHA. The electrode showed a good Nernstian slope of 30.0 ± 0.5 mV/decade in a wide linear range activity of 3.0 × 10⁻⁷ to 1.0 × 10⁻² mol dm⁻³ Cu(NO₃)₂ with limit of detection 2.5 × 10⁻⁷. Sensor exhibited a fast response time (t_95% < 10 s) and could be used for about 4 months in the pH range of 3.0–7.4. The proposed potentiometric sensor was found to work satisfactorily in partially non-aqueous media up to 30 (vol%) content of methanol, ethanol and acetone. Applications of this electrode for the determination of copper in real samples, and as an indicator electrode for potentiometric titration of Cu²⁺ ion using EDTA, were reported. In order to predict the extraction ability of NDHA for different metallic ions, the complexes [M(NDHA)] and [M(H₂O)₆] (where M = Cu²⁺, Co²⁺, Hg²⁺, Pb²⁺, Ag⁺, Mg²⁺, Ca²⁺, Mn²⁺, Zn²⁺, Cd²⁺, K⁺ and Al³⁺) were investigated using ab initio theoretical calculations. The metal binding capability was evaluated using the binding energy. Results of our study could be useful for prediction of the extraction power of this Schiff base and could play a guiding role in planning experiments.     

Construction of p-charts using degree of nonconformity

Control charts are among the simplest of on-line statistical process control techniques. When the quality characteristic is a variable, the p-chart takes time to react to shifts in the production process because of its weak response to small variations in the process mean and variance. In this paper, instead of considering an item to be either conforming or nonconforming, the “degree of nonconformity” based on fuzzy concepts is defined and a fuzzy p-chart based on the mean degree of nonconformity is constructed. It is shown that this chart has a better response to variations in both the mean and the variance of the process.     

An optimal residency-aware scheduling technique for cluster tools with buffer module

Cluster tools provide a flexible, reconfigurable, and efficient environment for several manufacturing processes (e.g., semiconductor manufacturing). A new timing constraint (distinct from a simple deadline), referred to as residency constraint, puts a timing limit on the time that a wafer can stay in a processing module in a cluster tool. The authors demonstrate that a solution that does not address residency constraints can be found easily. However, when residency constraints are added to the model, the problem becomes complex and a scheduling technique may spend a long time searching for a good solution. Also, in some cases, one may need to decrease throughput to satisfy residency constraints. The authors introduce a new technique to address cluster tool scheduling in the presence of residency constraints. The proposed technique uses a buffer resource for temporarily holding wafers to release other resources such as the robot arm. This resource is usually available in the tool for maintenance reasons. A tradeoff is discussed in using the buffer resource and a scheduling algorithm is presented that will use this resource when it can help to increase throughput under residency constraints. The experiments show that in many cases that are common in semiconductor manufacturing, use of their proposed technique can improve throughput.     

Making the best of those extra transistors

A new world for transistors may be on the horizon. The days of directly implementing custom functionality in transistors, and hence of designers creating their own chips, may be fading away. Prefabricated programmable platforms, considered grossly inefficient just a decade ago, may prevail, leading to lower costs, faster time to market, lower power, and other benefits perhaps not even foreseeable today.     

Study of reaction kinetics of epoxy and a nickel(II) complex using dynamic DSC technique

The curing reaction kinetics of an epoxy based on the diglycidyl ether of bisphenol A (DGEBA) with an inorganic complex based on nickel(II) chelate with ethylenediamine (en) as a ligand were studied using DSC in dynamic mode. The complex curing agent was synthesized and characterized by the elemental analysis, FT‐IR, and ICP‐Plasma techniques. Thermal dissociation behavior of curing agent was also studied using thermogravimetric (TG) analysis in isolated form. Three kinetic models, Kissinger, Ozawa‐Flynn‐Wall, and Expanded Freeman‐Carrole, were used to determine the kinetic parameters. The effect of hardener concentration on the kinetic parameters and the shape of DSC thermograms of the DGEBA/Ni(en)₃Br₂ system were investigated. Finally, the previous proposed mechanism by another researcher was used to explain the DSC data in detail. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 265–271, 2005     

Effect of temperature on geosynthetic rutting performance in asphalt pavement

In this research study, a 3D finite element model using ABAQUS software is used to evaluate the rutting performance of reinforced asphalt pavement. In this research study, the effects of three types of geosynthetic layers on the optimum location are studied at temperatures of 20°C, 40°C, and 50°C. According to the model analysis, the middle of asphalt layer is determined as the optimized location of geosynthetic layers in the pavement structure. The results showed that the effect of geosynthetic layers on rutting performance increased with increasing elastic modulus of geosynthetic at high temperature of pavement.     

Control of three phase PWM rectifier using virtual flux‐based predictive direct power control and SVM under harmonic conditions

In this paper, a new predictive direct power control algorithm to control the PWM rectifier based on virtual flux (VF) is presented. In this algorithm, supply network and the line inductances are assumed as an induction machine and so virtual flux space vectors are assumed corresponding with the space vector of the network voltages. Instantaneous active and reactive powers and finally convertor average voltage in both stationary and rotating reference frames are calculated by the virtual flux space vector components. The main advantages of the proposed method are low total harmonic distortion of the input current and low ripple in the instantaneous active and reactive powers and direct current‐bus voltage under harmonic distorted condition of the supply voltage in comparison with voltage‐based predictive direct power control (V‐PDPC) method. Proposed VF‐PDPC method with space vector modulation switching strategy was tested in simulations and compared with the V‐PDPC method. Copyright © 2015 John Wiley & Sons, Ltd.