Wire Matrix Research Articles

Vortex magnetic separation

Vortex magnetic separation (VMS) is a new technique (1-3) which can not only greatly increase selectivity of high gradient magnetic separation but can also provide a much higher material throughput because high slurry velocity is used. This technique will have a wide range of applications in fields as diverse as mineral processing, biochemical engineering, sewage and wastewater treatment and industrial effluent treatment. At present in high gradient magnetic separation (HGMS) low Reynolds numbers (with respect to the wire diameter) are usually used and the magnetic product is captured on the upstream side of the wire matrix which results in a serious mechanical entrainment problem that is very detrimental to the purity of the magnetic fraction and to the reduction of the quantity of non-magnetic fraction (4). Vortex magnetic separation runs at moderate Reynolds number ( Re = 6–40) which leads to the formation of vortex flow in the neighbourhood of the matrix. Magnetic particles in the slurry are first concentrated in the boundary layer flow around the matrix and then brought into the magnetically attractive area on the matrix downstream side. The magnetic deposit on the downstream side of the matrix does not suffer the direct collisions with non-magnetic particles in the slurry, so the quality of the magnetic product is drastically improved. As will be described below, a new invention has been made with regard to the VMS matrix which allows capture to take place on both the upstream and downstream sides of the matrix without mechanical entrainment. This paper reviews experimental and theoretical work on the mechanisms involved in vortex magnetic separation.

Heat Conductive Wire Matrix Board for Light Emitting Diode (LED) Dot Matrix Display

A wire matrix has been developed for mounting LED dot matrix displays whereby insulated wires are ‘woven’ to produce a matrix that is fixed on an aluminium board with epoxy adhesive. This monolayer woven wire board simplifies the fabrication process of the display board while at the same time showing more than double the heat dissipation of conventional insulated aluminium printed circuit boards and five times that of conventional glass epoxy printed circuit boards when mounted with bare LED chips. In addition, it is suitable for high‐density and high‐brightness LED dot matrix displays.

Determination of lead in preserved egg by flame atomic absorption spectrometry after chemically modified preconcentration

A sensitive method for the determination of lead in preserved egg by flame absorption spetrometry using ammonium pyrrolidine dithiocarbamate-polystyrene chemically modified platinum wire matrix is presented. The modified platinum wire matrix, after preconcentrating the lead, is placed in a flame burner for direct atomization and measurment. The concentration range is linear between 5 and 500 ng/ml lead in solution and the detection limit is 0.65 ng/ml. This new technique is sensitive and convenient.

Proprinter design for manufacturability

Design for assembly is a design trend in industry for developing products with few parts so that they can be manufactured easily on an automated assembly line. This concept is embodied in the IBM proprinter. This table top printer is a wire matrix type for the company's personal computer line. The printer does not have the usual array of screws, pulleys, belts and brackets. The parts simply snap together. This paper attempts to make recommendations for further improvements in the area of producibility of the printer.

The design for a high-Tc superconducting magnetic separator

A number of options for the design of a superconducting high-Tc magnetic separator have been considered and it is suggested that, when material properties have improved sufficiently, a separator based on a flux tube with a flux pump will offer significant advantages. Another design for a more detailed evaluation was chosen based on an iron magnetic circuit in which amper-turns were supplied by a superconducting BSCCO-Ag tape wound coil operating at 77 K. Two configurations for the separator were considered, a ball matrix separator and a wire matrix high-gradient separator. Practical separations will be possible with such a system.

Tablet Using Matteucci Effect of Amorphous Magnetic Wires

This article describes a new tablet for inputting handwritten characters to computers using amorphous magnetic wires employing the Matteucci effect, which is sensitive to perpendicular ac magnetic fields. The Matteucci voltage e M with a double-frequency-pulse shaped ac voltage is induced across the ends of an amorphous wire when an arbitrary point is vertically magnetized by a pen-shaped coil with an amorphous magnetic core. The value of e M was nearly constant as the pen was slid along the wire, but rapidly decreased with pen displacement vertical to the wire. An amorphous wire matrix was constructed, with each of the ten wires in the X and Y directions spaced at 5 mm intervals, and with Matteucci voltage pulses converted to dc voltages through peak-holders. Handwritten characters are displayed on a microcomputer display using a multiplexer, A/D converter, and position detection software.

Determination of trace amounts of gold in waste water by graphite furnace atomic-absorption spectrophotometry with preconcentration on trioctylphosphine oxide chemically modified tungsten wire matrix

Preconcentration on a trioctylphosphine oxide (TOPO) chemically modified tungsten wire matrix followed by graphite furnace atomic-absorption spectrophotometry measurement is described for the determination of trace gold in waste water. The TOPO modified tungsten wire matrix, after accumulating the gold, is placed in a graphite cup for direct atomization and measurement. Under the selected conditions, the absorbance is proportional to the concentration of gold over the range 0.4–18 ng/ml and the detection limit is 0.2 ng/ml. This method is sensitive and convenient. It has been applied to some waste waters with satisfactory results.

Data tablet utilizing Matteucci effect of amorphous magnetic wire matrix

An accurate and reliable data tablet or digitizer was constructed utilizing the Matteucci effect for an amorphous magnetic wire matrix. Cold-drawn amorphous wires with 50- mu m diameter having a composition of (Fe6Co94)72.5Si12.5B15 were used in a tablet plane. An AC magnetic field of 140 kHz was perpendicularly applied to the amorphous wires to induce a double-frequency Matteucci voltage between both ends of each amorphous wire. A small DC current of 2-5 mA was applied to the wire-axial direction for initial setting of its circular magnetization direction when the Matteucci voltage was detected. External disturbance fields did not influence on the Matteucci effect in the folded amorphous wires with a small DC current. Hand-written characters were shown on a CRT display using the data tablet.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

アモルファス磁性ワイヤの垂直励磁Matteucci効果によるタブレット

This article describes a new tablet for inputting handwritten characters to computers using amorphous magnetic wires employing the Matteucci effect, which is sensitive to perpendicular ac magnetic fields. The Matteucci voltage e M with a double-frequency-pulse shaped ac voltage is induced across the ends of an amorphous wire when an arbitrary point is vertically magnetized by a pen-shaped coil with an amorphous magnetic core. The value of e M was nearly constant as the pen was slid along the wire, but rapidly decreased with pen displacement vertical to the wire. An amorphous wire matrix was constructed, with each of the ten wires in the X and Y directions spaced at 5 mm intervals, and with Matteucci voltage pulses converted to dc voltages through peak-holders. Handwritten characters are displayed on a microcomputer display using a multiplexer, A/D converter, and position detection software.

Influence of transverse compressive and axial tensile stress on the superconductivity of PbMo 6S 8 and SnMo 6S 8 wires

The behaviour of the critical current density, J c, of PbMo 6S 8 and SnMo 6S 8 monofilamentary wires with external transverse compressive stress, σ t, and axial tensile stress, σ a, was investigated. Varying the reinforcing steel content in the wire matrix, different axial prestress states, e.g. the compressive, tensile and unstressed state were realized. The observed variation of J c, versus σ a was significantly smaller compared with that of Nb 3Sn wires, which is explained by the higher upper critical magnetic field, B c2, of the Chevrel phase. The elastic strain range of 0.6–0.8% (with 0.2% compressive prestrain of the filament) fulfils the requirements for future technical applications of this type of wire material. The effect of transverse applied compressive stress, σ t, on I c and B c2 ∗ of the Chevrel phase wires was investigated in magnetic fields up to B = 22 T and T = 4.2 K. Analogous to Nb 3Sn wires, a strong degradation of the critical current density with σ t was observed. As for the axial tensile stress, the influence of σ t on J c is found to increase with the applied magnetic field. At 20 T the transverse compressive stress effects reduce J c about twice as much as the axial tensile stress. At present externally steel reinforced PbMo 6S 8 wires can be compared with Nb 3Sn wires, the effect of transverse stress appears to be considerably smaller in the Chevrel phase wire, possibly as a consequence of the higher upper critical field with respect to Nb 3Sn.

Multigradient Dielectrophoresis: Wire Grid Matrix Optimization and Current Modelization at High Loading

Abstract The various processes for separation with electric fields are briefly recalled with emphasis on dielectrophoresis. For dielectrophoietic filtration in nonaqueous liquids, a wire matrix optimization study shows that wires must be as thin as possible to maximize forces and at a distance to radius ratio below 5 for the best use of the electrified space. A model is proposed for the variation of the electric current measured as particle buildup is progressing. Numerical calculations are reported demonstrating the importance of transient effects. It is also mentioned that a more sophisticated approach incorporating the nonlinear behavior of conductivity vs field intensity is adequate to take into account effects occurring at high field intensities. Finally, practical design considerations are presented.

A superconducting high-gradient magnetic separator with a current-carrying matrix

A new magnetic separator is presented consisting of a current-carrying wire matrix in an applied magnetic field. This machine has particular advantages with superconducting magnets. The wires trap weakly magnetic particles from a fluid, either liquid or gas, which carries the particles through the wire matrix. High processing rates and high selectivity of material in magnetic susceptibility and in particle size can be achieved with low power input. A wide range of susceptibility material can be treated simultaneously. This separator has no moving parts.

Effective thermal conductivity of a metal hydride bed augmented with a copper wire matrix

The effective thermal conductivity K' e of a copper wire matrix improved metal hydride bed of MmNi 4.46Al 0.54 powder has been measured using a steady state method. Effects of the copper wire matrix, the metal hydride itself, the system pressures and the hydrogen-to-metal atom ratio ( H M ) on K' e are analysed and expressed through an empirical equation.

Superconducting high gradient magnetic separator incorporating a current carrying wire matrix

A new superconducting magnetic separator incorporating a current-carrying wire matrix with a background field, has been investigated. Within this matrix, magnetic particles carried by a fluid, are trapped by the wires. Theoretical studies show that firstly it is necessary to use bifilar wires. The tractive force exerted on the particles in this system, diminishes as the wire separation is decreased. Secondly, the current in the wires can be switched on and off extremely quickly resulting in an extremely efficient separation process. Experimental observation of captured material was made as a function of slurry velocity V o and magnetic velocity V m . The amount of captured material was found to decrease with the ratio V m /V o .

The (comparative) performance of HGMS -- Filters with a strictly ordered wire matrix in the axial and transverse configuration

We present experimental data on the initial efficiencies of axial and transverse HGMS-filters with a periodically ordered wire matrix. The efficiencies were determined for particles in narrow size ranges by a photo-sedimentation analysis. We also compare the experimental data with the predictions of our recently developed multiwire theories for the performance of axial and transverse filters.

Designing HGMS matrix arrays for selective filtration

High Gradient Magnetic Separators typically use a random array of wire matrix elements such as stainless steel wool or expanded metal for the magnetic capture of fine particles. Difficult mineral separation tasks may require systematic and controlled matrix construction to allow more selective separation of one material over another. Of interest here is the dependence of the magnetic capture force on the spacing and shielding of wire matrix elements and how such design parameters lead to a more selective matrix array. A laboratory technique developed in our group provides good confirmation of computer modeling studies. We use arrays of nickel or iron wires, spaced from 6 to 30 times the wire radius. Magnetite filled epoxy is added to the volume around the wire matrix. The wires are magnetized to saturation and the dispersed magnetite moves away from the negative gradients above and below the magnetized wires. The computer studies correlate to the magnetite patterns observed.

Magnetic filtration by a current-carrying wire matrix

The mechanisms of magnetic particle capture by current-carrying conductors are examined. Equations are derived which describe particle trajectories in the vicinity of cylindrical conductors in terms of an amperian magnetic velocity. Some preliminary filtration experiments with a current-carrying wire matrix are also described.

Improvements of a low-field, high-intensity matrix separator

A high-intensity magnetic separator, which employs a ferromagnetic wire matrix in a low magnetic field, has been described and analysed, previously. In this paper, the improvement in performance with the reduction in magnetic field is shown to be limited to the field H <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">L</inf> . where <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">k (= M/2\mu_{o}H_{L})</tex> becomes equal to unity. <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">M</tex> being the magnetization of the matrix strands. However, it is shown that it is possible to obtain further improvements in performance, at magnetic fields lower than this limit, by the use of an hysteretic matrix. This involves first magnetizing the matrix in a high field before reducing the field to a low operating value, which may even be zero. The captured material is removed after the matrix is demagnetized.

ワイヤドット式漢字プリンタの印字機構設計法

This paper treats with a design method of wire matrix print heads adopted to a lot of present data terminals, and describes the development of a Kanji printer. A free-flight wire mechanism has been introduced for the purpose of high-speed printing, untroublesome operation, easy maintenance, and self-compensation of the wire length against the wear. The investigation of fine wire printing conditions results in the high-quality matrix printing technology equal to full stroke printing in the use of smallest wires in diameter (0.2 mm) as well as the invention of a print wire arrangement. The wire diameter is fattened abruptly to 0.5 mm at the half of the longitudinal way in order to minimize the transmission loss of the printing energy. High-speed drive of the print wires has been performed by means of the reduced weight of wires and armatures, and of trapezoidal magnet-core invention. On the basis of the above-mentioned fundamental technologies, a Kanji printing mechanism has been developed and the proposed design method has been confirmed.

Accelerator evaluation of a spark-chamber experiment for gamma-ray astronomy

The ESRO satellite COS-B will carry a single experiment, aiming at the detection and energy measurement of cosmic gamma radiation at energies above 25 MeV. The instrument incorporates a wire matrix spark chamber and a caesium-iodide energy spectrometer. The response of the instrument to gamma rays has been determined using a tagged gamma-ray beam (25–300 MeV). A first estimate of the susceptibility to charged-particle background has been obtained from an exposure of the instrument to protons of 1450 MeV/ c. The measured performance characteristics of the experiment are presented and discussed. As a result of the tests improvements in the design of the flight instrument, leading to increased sensitivity to gamma rays and a lower susceptibility to background, could be incorporated.