Fabrication of nanograined silicon by high-pressure torsion

This paper describes fabrication of Si nanograins through allotropic phase transformation by concurrent application of high pressure and intense straining using high-pressure torsion (HPT). Single-crystalline Si(100) wafers were processed by HPT under a pressure of 24 GPa at room temperature. X-ray diffraction and Raman analysis revealed that the HPT-processed samples were composed of metastable Si-III and Si-XII phases and amorphous phases in addition to the original diamond-cubic Si-I phase. It was found that nanograins formed because the Si-I diamond phase had transformed to high-pressure phases (Si-II, Si-XI, and Si-V) having metallic nature, and it then became easier to generate a high density of dislocations to form grain boundaries. The high-pressure phases were further transformed to the Si-XII and Si-III phases via the Si-II phase upon unloading and they existed as metastable phases at ambient pressure. Subsequent annealing at 873 K gave rise to reverse transformation to Si-I but with nanograin sizes. Although no appreciable photoluminescence (PL) peak was observed from the HPT-processed sample, a broad PL peak centered around 600 nm was detected from the annealed sample due to quantum confinement in the Si-I nanograins.     

Reducing temperature stratification using heated air recirculation for thermal energy saving

Using discrete heat sources such as a radiator or a gas heater, a large amount of heated air is accumulated under the ceiling surface where it is usually far enough from the occupancy zone. The idea of transferring this heated air into the occupancy zone has been the subject of the present study. A full length-scale model of a compartment was constructed and equipped with a radiator and an air circulating mechanism. Temperature distribution on the symmetry plane was specified for the two cases of usual heating and heating with air circulation. Heat loss from the surfaces of the enclosure was also determined using thermal maps of both the internal and the external surfaces of the enclosure. In order to examine the effect of circulating air on the thermal energy saving quantitatively, a numerical model was developed and validated using experimental results. The input heat rate of the enclosure was compared for the two cases of usual heating and heating with air circulation considering different heights for a typical heating space. Based on the results, having the same mean air temperature within the occupancy zone, the input heat rate of a compartment could be moderated using circulating air criterion.     

The UCR Time Series Archive

The UCR time series archive – introduced in 2002, has become an important resource in the time series data mining community, with at least one thousand published papers making use of at least one data set from the archive. The original incarnation of the archive had sixteen data sets but since that time, it has gone through periodic expansions. The last expansion took place in the summer of 2015 when the archive grew from 45 to 85 data sets. This paper introduces and will focus on the new data expansion from 85 to 128 data sets. Beyond expanding this valuable resource, this paper offers pragmatic advice to anyone who may wish to evaluate a new algorithm on the archive. Finally, this paper makes a novel and yet actionable claim: of the hundreds of papers that show an improvement over the standard baseline (1-nearest neighbor classification), a fraction might be mis-attributing the reasons for their improvement. Moreover, the improvements claimed by these papers might have been achievable with a much simpler modification, requiring just a few lines of code.      

Wavefront reduction using graphs,neural networks and genetic algorithm

This paper presents an algorithm for nodal numbering in order to obtain a small wavefront. Element clique graphs are employed as the mathematical models of finite element meshes. A priority function containing five vectors is used, which can be viewed as a generalization of Sloan's function. These vectors represent different connectivity properties of the graph models. Unlike Sloan's algorithm, which uses two fixed coefficients, here, five coefficients are employed, based on an evaluation by artificial neural networks. The networks weights are obtained using a simple genetic algorithm. Examples are included to illustrate the performance of the present hybrid method. Copyright © 2004 John Wiley & Sons, Ltd.     

Chemical reaction interface mass spectrometry with high efficiency nebulization

A high efficiency nebulizer (HEN) coupled to a heated spray chamber and a membrane desolvator is used for liquid sample introduction in chemical reaction interface mass spectrometry (CRIMS). Compared to the conventional thermospray nebulizer operated at solvent flow rate of 1 mL/min, the HEN provides small droplets at lower flow rates (10-100 microL/min), improving the desolvation and analyte transport efficiency. As a result, the sensitivity for carbon detection by CRIMS is improved by a factor of 4. The new arrangement offers an easy-to-use and robust interface, facilitating the availability of a variety of liquid chromatographic techniques to the CRIMS. Separation and detection of labeled peptides in a mixture of unlabeled biopolymers is illustrated at a solvent flow rate of 45 microL/min as an example of new possibilities offered by the improved liquid introduction interface.     

Noncontact roughness measurement of turned parts using machine vision

The surface roughness of turned parts is usually measured using the conventional stylus type instruments. These instruments, although widely accepted, have several limitations such as low speed measurement, contacting in nature, requiring vibration-free environment, etc. Machine vision methods of roughness measurement are being developed worldwide due to their inherent advantages, including noncontact measurement, high information content, rapid measurement, and surface measurement capability. In past research, area-based light scattering method and gray scale line intensity measurement have been developed for roughness assessment using machine vision. Such methods, however, produced redundant data when applied to measure roughness of turned parts. In this paper, an alternative method of roughness measurement using the 2-D profile extracted from an edge image of the workpiece surface is proposed. Comparison with a stylus type instrument shows a maximum difference of 10% in the measurement of average roughness R _a using the vision method.