Low-power,noninvasive measurement system for wearable ballistocardiography in sitting and standing positions

Ballistocardiography (BCG), the noninvasive measurement of the reaction forces of the body to the cardiac ejection of blood, is one of few methods available for unobtrusively assessing the mechanical aspects of cardiovascular health outside clinical settings. In this study, two sizes of piezoelectric film sensors were installed into the seat cushion of a chair and the foot insole, respectively, to acquire local BCG signals in sitting and standing positions. The design and engineering implementation of the signal processing circuit and data transmission system are discussed below. Although wearable BCG measurement devices have been extensively researched to date, to the authors’ knowledge, they have never been tested in regards to power consumption and electrostatic discharge (ESD) immunity. In this work, comprehensive experiments were conducted to show the low power consumption and high reliability of the proposed system. The shapes and the amplitudes of measured signals were examined in detail. The results suggest that the proposed system can feasibly and reliably be used to continuously record and evaluate cardiovascular changes occurring throughout an individual’s daily life.     

Charge measurement using an array of Faraday’s Cups on a printed circuit board

An absolute method of measuring charge is to use a Faraday Cup (FC) principle. This study relates to a novel method of measuring charge on a flat substrate, which is coated with charged powder particles. The substrate consists of an array of FC with different dimensions. The sensor is manufactured using flame-retardant printed circuit board (PCB) technology. The objective of this work is to reduce the charge sharing by developing a grounded shield cup around each conductive cup in the array and accordingly increase cup-to-ground capacitance. The results have confirmed that the improved well shielding would provide a more accurate quantitative charge measurement.     

Size and shape dependent steady-state pull-off force in molecular adhesion between soft elastic materials

This paper aims to study the size- and shape-dependent steady-state pull-off force in molecular adhesion between two soft elastic materials. The adhesion consists of a patch of non-covalent bonds formed between ligand and receptor molecules on opposing adhesion surfaces. Classical contact mechanics is used to model the deformation of elastic materials while Bell’s model is adopted to describe stochastic breaking/reforming of molecular bonds. A coupled elastic-stochastic model is established to show that there exists a critical adhesion size, which leads to a critical stress concentration index after proper normalization, beyond which stress concentration near the contact edge causes crack like failure of the adhesion patch governed by Griffith’s criterion and below which the pull-off traction is saturated at a constant strength governed by Bell’s model of molecular adhesion. In addition to size effect, optimal adhesion can also be achieved by designing the shape of the contact surfaces, although it is sensitive to small variations in shape at large adhesion size or stress concentration index. A robust, shape-insensitive high-strength adhesion state becomes possible when the adhesion size or the stress concentration index is sufficiently small.     

Supervised two-step feature extraction for structured representation of text data

Training data matrix used for classification of text documents to multiple categories is characterized by large number of dimensions while the number of manually classified training documents is relatively small. Thus the suitable dimensionality reduction techniques are required to be able to develop the classifier. The article describes two-step supervised feature extraction method that takes advantage of projections of terms into document and category spaces. We propose several enhancements that make the method more efficient and faster than it was presented in our former paper. We also introduce the adjustment score that enables to correct defected targets or helps to identify improper training examples that bias extracted features.     

Structure and dielectric characteristics of continuous composition spread Ba1−xSrxTiO3 thin films by combinatorial pulsed laser deposition

Ba_1−xSr_xTiO₃ (0≤x≤1, BST-x) continuous composition spread thin films were grown on SrTiO₃ substrates buffered by La_0.9Sr_1.1NiO₄ (LSNO) electrodes using combinatorial pulsed laser deposition. The effects of Sr concentration on the structure and dielectric properties of the Au/BST-x/LSNO capacitors were investigated. X-ray diffraction patterns and reciprocal space maps revealed that both the in-plane and out-of-plane BST-x lattice parameters decreased with the increment of Sr content. Impedance measurements showed that the dielectric constant and tunability simultaneously changed with Sr concentration and reached the maximum at about x=0.5, which is comparable to that of BST-x individual thin films or bulks. Our results showed the large potential of combinatorial method in optimizing materials properties and even finding new materials.     

Impact dynamics with applications to solid particle erosion

A reformulation and solution is presented of the equations of impulse and momentum for an arbitrarily shaped rigid body striking a flat massive surface. The model makes use of the classical coefficient of restitution, e, and tangential coefficient, μ. The latter is defined as the ratio of the tangential to normal impulse components. It is shown that a distinction between μ and friction coefficients, f, is necessary for a proper interpretation of impact data.The expression of impact energy loss is placed into a particularly convenient form. Comparisons are made of this impact model to others from the field of solid particle erosion and wear.     

Industrial Experiment on Coke Spraying With ZBS Additive in Blast Furnace

In order to improve the thermal properties of coke, an industrial experiment on the coke spraying with ZBS additive solution was carried out at coking plant and No. 6 blast furnace （2 000 m^3 ） of Kunming Iron and Steel Co Ltd. The coke reaction index （CRI） of the coke spraying with ZBS additive solution decreases by 10. 56 %, and the coke strength after reaction （CSR） increases by 7.80% in comparison with those of the un-sprayed coke. During the experiment, the average iron output increases by 66. 69 t/d, and the coke rate is reduced by 5. 21 kg per ton iron, while the fluctuation of furnace temperture is small, and sulphur content in hot metal and 100% of hot metal are acceptable.