Extraction of Rare Earth Elements as Oxides from a Neodymium Magnetic Sludge

We propose a simple method for separating rare earth elements as oxides from a neodymium magnetic sludge by focusing on the affinity of oxygen for the rare earth elements (Nd, Dy, and Pr) and Fe. We have conducted separation experiments with a carbon crucible as contact material to confirm that carbon maintains the oxygen potential in the coexistence region of rare earth oxides and metallic Fe. In this work, the oxide phase of the rare earth elements and the alloy phase that primarily consists of Fe were separated clearly when the magnetic sludge in the carbon crucible was kept at 1823?K (1550?°C) under an Ar atmosphere. The purity of the rare earth oxide phase was high and only a small amount of rare earth elements were contained in the alloy phase. We found that the melting temperature of the rare earth oxides is a crucial factor for separation efficiency in our proposed method.     

Mixed-order sampling of 2-D frequency distributions by using the concept of common superset

Multidimensional Systems and Signal Processing - It has been found that tiling clusters and pair regions of frequency distributions play an important role in the sampling problems. When a given 2-D...     

Silver Nanowire Electrodes: Conductivity Improvement Without Post-treatment and Application in Capacitive Pressure Sensors

Nano-Micro Letters - Transparent electrode based on silver nanowires (AgNWs) emerges as an outstanding alternative of indium tin oxide film especially for flexible electronics. However, the...     

Engineering problems in machine learning systems

Machine Learning - Fatal accidents are a major issue hindering the wide acceptance of safety-critical systems that employ machine learning and deep learning models, such as automated driving...     

Frequency Response Characteristics of Bender Element Test System Identified by Frequency-Swept Signal Input —Influence on Accuracy of Received Waveform Reconstruction—

On the basis of the method for received waveform reconstruction that the authors had previously proposed on bender element test, this paper discusses the required characteristics of frequency response of the test system and frequency-swept signal, which are essential for the method, from the view point of reconstruction accuracy. In order to argue influence on characteristics of frequency response, frequency responses of several bender element test systems are experimentally identified by using eleven kinds of frequency-swept signals. Test results show that the frequency response of the system is substantially determined by the kinds of sample and identification of frequency response is affected by characteristics of input frequency-swept signal. Then reconstructed received waveform is calculated and compared to observed waveform. A normalized cross-correlation function is proposed to estimate quantitatively the degree of similarity between two waveforms and applied to the reconstructed and observed waveforms. This comparative analysis reveals that accurate identification of frequency response in a given frequency range leads to accurate waveform reconstruction. Also, test results show an additional advantage of this reconstruction technique in a noisy environment.     

CMP process run-to-run control to adjust margin in control limit

This paper describes a run-to-run control method based on within-wafer distribution of film-thickness and removal rate. The main feature of this method incorporates adjusting the lower and upper margin of the film-thickness after CMP. The margins represent the differences of the minimum and maximum film-thickness values from the lower and upper control limits, respectively. In order to realize this concept, (1) the removal-rate within-wafer distribution is modeled as a polygonal line profile using the results of blanket-wafer polishing, (2) the removal rate at measurement sites of the product wafer is derived from the profile to adjust for differences between product types, (3) the profile is updated with the results of product wafer polishing in the work sequence, and (4) polishing time is calculated so that it satisfies the condition wherein the margin on the upper side equals the margin on the lower side within control limits to prevent film-thickness failure due to run-to-run variations. A capability index based on the margins is suggested and actual production results are shown using this index, which indicates a 71.6% improvement in accuracy and precision.     

Relation between segregation patterns and granular flow modes in conical rotating drum

Generally, it is difficult to observe, without any disturbance, flow structures or velocities inside flows such as granular flows, particle-fluid flows and so on. It is effective to use a non-contact and non-destructive measurement method for such flows. In the present paper, an MRI (Magnetic Resonance Imaging) technique is employed to measure the motion and velocity inside the flows. MRI has been applied to granular flows since about 1990. Our group has studied the particle motion inside the rotating drum using MRI. The rotating drum is industrial equipment which is widely utilized in engineering processes. In the cylindrical rotating drum it is well-known that axial and/or radial segregation take place. In the present study, we use a conical rotating drum which is sometimes employed in the granulation process. The conical rotating drum is half-filled with a mixture of two different sizes of spherical particles. We varied the rotational speed. Then we investigated the effect of the rotational speed on the axial segregation pattern and observed the flow mode.