Magnetic Tape Recording Research Articles

Use of Nanoparticles in Soil-Water Bioremediation Processes

As a general definition, nanotechnology is involved with objects on the nano scale, or materials measuring between 1 and 100 nm. It was found a good definition that is practical and unconstrained by any arbitrary size limitations: The design, characterization, production, and application of structures, devices, and systems by controlled manipulation of size and shape at the nanometer scale that produces structures, devices, and systems with at least one novel/superior characteristic or property (Bawa et al., 2005). Nanotechnology has contributed to the development of a great diversity of materials as those used in electronic, optoelectronic, biomedical, pharmaceutical, cosmetic, energy, catalytic, and materials applications. In the manufacturing community, the most profitable trail for nanoscale particles and materials have been in the areas of sunscreen, magnetic recording tape, automotive catalyst supports, biolabeling, chemical-mechanical polishing, electroconductive coatings, and optical fibers. However, the emergence of nanotechnology presents a number of potential environmental benefits. This potential impact area could be divided into three categories: treatment and remediation, sensing and detection, and pollution prevention. Some nanoparticles destroy contaminants, for instance, while others sequester them. The specific nanotechnologies that it will be discussed hereafter focus on site remediation and waste water treatment. Besides the applications for soil, groundwater, and wastewater, a number of nanotechnologies for air remediation are also in development. Carbon nanotubes, for example, have been recognized for their ability to adsorb dioxin much more strongly than traditional activated carbon. Smaller particle size enables the development of smaller sensors, which can be deployed more easily into remote locations. The ability of nanotechnology to abate pollution production is in progress and could potentially catalyze the most revolutionary changes in the environmental field (Watlington, 2005).

Dropout Compensation by Equalizer Selection and Kalman Filter-Based Timing Recovery

When occasional dropouts occur in magnetic tape recording systems because of defects and debris, the readback signal exhibits amplitude loss, pulse widening, and peak shifts, and the corresponding entire data block may be lost. In this paper, we develop a dropout compensation method that works in conjunction with the interpolated timing recovery method. In this method, we estimate the readback signal envelope and use it as a measure of the depth of a dropout. On the basis of the estimated envelope, an equalizer can be selected from a pretrained filter bank to transform the distorted transition response in a dropout to the desired partial response target. In addition, a Kalman filter-based scheme can be used to determine the phase and the frequency update gains in the timing recovery loop. We show that, by using Kalman filter-based timing recovery, more dropouts can be compensated

James Alfred Van Allen

James Alfred Van Allen

Fabrication of CoCrPt–SiO 2 films on flexible tape substrate using facing target sputtering system

Magnetic properties of CoCrPt–SiO 2 films using facing target sputtering system were investigated. CoCrPt–SiO 2/Ru thin films were deposited directly on slide glass substrate and flexible tape substrate (ARAMID) without seed layers in various sputtering conditions aiming for development of CoCrPt–SiO 2 magnetic recording tape media. It was suggested that the Ar gas pressure in fabrication of magnetic layer and underlayer had an influence on magnetic property. Ru (0 0 1) orientation was degraded at high Ar gas pressure in fabrication of underlayer. Longitudinal magnetic recording layer can be fabricated on tape substrate without seed layer. Coercivity and M r/ M s of that film were 4270 Oe and 0.78, respectively.

Observation of Magnetization of Obliquely Evaporated Co-CoO Magnetic Recording Tape

Electron holography is effective for the study of the micromagnetic structure of various advanced magnetic materials. Although the microstructure of obliquely evaporated Co-CoO tapes has been explicitly described so far, the investigation of magnetization in the as-recorded state is indispensable for the in-depth understanding of the magnetization transition mechanism of the tape. In this study, for the first time, a clear image is shown depicting the magnetization transition of an oblique Co-CoO tape obtained by electron holography. The image is compared with those obtained by computer simulation taking into account the recording process. It is found that although the easy axes of Co crystal particles are titled at approximately 45deg to the tape plane, the recorded magnetization shows a circular shape with its center located slightly above the center plane of the tape. Using the images of the magnetization, some possible ways to improve the recording performance of the tape are discussed

Cyclic Equalization and Channel Identification for Magnetic Tape Recording Systems Using the Data Set Separator

This paper addresses the problems of equalizer design and channel identification for read channels implemented in linear tape open (LTO) tape-drive systems. The techniques presented use the readback waveform of the data set separator (DSS), a special pattern that is recorded at specific locations on tape as part of the LTO format. The concept of cyclic equalization is employed for a DSS-based equalizer design. The approach is extended to channel identification for extracting the dibit response of the magnetic recording channel from the DSS readback waveform. Both techniques are implemented with low complexity, making them attractive for practical realizations. Actual readback signals captured on commercial LTO tape-drive systems are used to demonstrate the efficiency of the described techniques

Vector vibrating-sample magnetometer with permanent magnet flux source

A compact magnetometer, which uses two nested 1T Halbach cylinders to generate a variable magnetic field of up to 2T in any direction in the xy plane, has two sets of quadrupole pickup coils to detect the components mx and my of the magnetic moment of a sample vibrating along Oz. Sensitivity is 1.10−7Am2 with integration time of 100ms. The instrument is used to measure longitudinal and transverse hysteresis loops and torque curves, under automatic software control. Three examples illustrating its versatility and sensitivity are provided: CrO2 magnetic recording tape, a cobalt nanowire array in a porous membrane, and a FePt thin film.

Nanocluster deposition for high density magnetic recording tape media

A technique for the fabrication of ultra-high density magnetic recording tape media with no risk of heating polymer substrate is reported. In this approach magnetic nanoparticles were generated by combining gas-phase nanocluster deposition and on-line heating techniques and deposited onto polymer substrate. Magnetic properties of the nanoparticles were optimized during their flight in vacuum prior to deposition. This technique is materials independent and it can fabricate nanocomposite films with high coercivity and very small film thickness. The fabricated magnetic nanoparticles have a uniform size distribution [for CoPt, 8.4% (standard deviation)] and well-defined spherical shape.

Retrospectroscope - Science, technology and the researcher

Presents an historical overview of biomedical engineering research from the 1950s to present times. Topics include magnetic analog tape recorders; biotelemetry; digital computers; grant applications. Focus on modern research topics include: biotechnology; tissue engineering; nanotechnology; and implantable drug delivery systems.

Infant speech development: A report of the study of one child by magnetic tape recordings

Infant speech development: A report of the study of one child by magnetic tape recordings

Investigation of tape edge wear of magnetic recording tapes

Tape edge wear is studied for polyethylene naphthalate-based magnetic tape as a function of tape speed, tape tension, and tape guide surface roughness. The results show that tape edge wear is on the order of 0.04 nm per cycle at a constant force of 45 mN and that edge wear increases with increasing tape speed, tape tension and tape guide surface roughness. In addition, tape edge wear of three coated tapes with polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and polyaramid (PA) substrate is studied. It is found that edge wear of polyaramid based tape is similar to that of PET-based and PEN-based tapes.

メカノケミカル法による有機塩素化合物の分解

Chlorinated organic chemicals such as 1, 2, 3-trichlorobenzene (TCB), monochlorobiphenyl (BPCl), and magnetic recording tape were subjected to grinding with and without an additive to decompose their structures mechanochemically. The additive was CaO, and the mill used in the experiment was a planetary mill. After the grinding, a washing operation using water was conducted to separate the soluble compound from the product by filtration. The ground product and the filtrate were characterized by ion chromatography (IC), gas chromatography (GC/MS), X-ray diffraction (XRD), Raman spectroscopy, electron spin resonance (ESR) and inductivity coupled plasma (ICP). The conversion of the chlorinated organic chemicals was almost 100% by prolonged grinding, where radicals played a significant role in the decomposition and the yield of the ground samples. This operation would be applicable to the decomposion of other chlorinated organic substances.

Review of basic chemistry of UV‐curing technology

The market for ultraviolet curing technology has been growing at double‐digit rates in the last 10 years. The main reason for such a rapid technological growth of UV curing is its unique process characteristic, which allow UV‐coating to be applied on virtually any substrates, including plastic, metal, composite, wood, paper, leather, vinyl, glass, magnetic recording tape and even human teeth. The original driving forces behind the commercialisation of UV‐technology were energy saving and freedom from solvents. These benefits are complemented by high productivity and subsequently higher profits that can be achieved with the increased line speed, just‐in‐time benefits and immediate “pack and ship” capabilities. This paper gives a review of the development of the UV curing technology, with emphasis placed on relevant chemistry.

Reversed Gyroremanent Magnetization in<tex>$gamma$</tex>-Fe<tex>$_2$</tex>O<tex>$_3$</tex>Particulate Systems

Gyroremanent magnetization (GRM) has previously been studied in connection with the well-known technique of ac demagnetization, which is used extensively in rock magnetism, palaeomagnetism and magnetic materials research. The "normal" GRM effect was explained by Stephenson in 1980, but recently a "reversed" GRM was obtained in a CrO/sub 2/ particle system by Madsen. We have studied samples of /spl gamma/-Fe/sub 2/O/sub 3/ particles (commercial magnetic recording tapes) and have identified samples with both "normal" and "reversed" GRM. The amplitude of the ac field was found to essentially influence the character of the GRM. In this paper, we also present micromagnetic simulations of the GRM in systems of single-domain particles and the results are discussed. Both "normal" and "reversed" GRM have been obtained in the simulations.

The evolution of molecular biology.

Biology's various affairs with holism and reductionism, and their contribution to understanding life at the molecular level

Simple processing method and characterisation of nanosized metal powders

There is an increasing demand for fine metal powders with sizes below 1 μm for a range of applications including catalysts, sintering aids, magnetic recording tapes, magnetic fluid, additives for propellants/explosives, microwave absorption, batteries and electronic applications. Recent research at University of Birmingham has led to the development of a simple and flexible processing method of nanosized powders of elemental, alloy and compound materials. Their particle size, morphology and distribution have been characterised using transmission electron microscopy (TEM). The oxidation behaviour and the magnetic properties of the nanosized powders have been studied using differential scanning calorimetry (DSC) and vibrating sample magnetometer (VSM), respectively. This paper highlights the microstructure and properties of the nanosized Al, Fe, Ni, Cu and TiN powders produced by this simple method.

Rotational magnetization measurements on magnetic particle recording tape

Rotational vector measurements have been made on a magnetic particle tape for a sequence of rotating applied fields. From these measurements, polar plots are made of the magnetization trajectories. The rotational accommodation and the rotational energy losses are computed from these trajectories as a function of the applied field.

The characterisation of magnetic pigment dispersions using pulsed magnetic fields

In this work, we describe the application of pulsed field magnetometry techniques for the characterisation of magnetic pigment dispersions. Magnetic pigment dispersions are important technological materials as in one form they are the material which are used to coat base film in order to make magnetic recording tape. It is these materials that have been evaluated. In this work, we describe the use of two pulsed field magnetometers, one being a low-field instrument with a maximum field of 750 Oe and the other a high-field instrument with a maximum field of 4.1 kOe. Using inductive sensing, the magnetisation is monitored in real time as the pulse is applied. We find that using these techniques we can successfully monitor the progress of the dispersion process, the effects of different resin systems and the effect of different processing conditions. We find that our results are consistent with rheological and other measurements.

Method for the synthesis of CrO2 at ambient pressure and temperature

In this article, we report the synthesis of metastable chromium dioxide at ambient temperature and pressure. The formulation of this method is based on the fact that the CrO2 particles used in magnetic recording tapes are chemically unstable and react with the organic binder, leading to a disproportionate reaction that produces nonmagnetic Cr(III)OOH and H2Cr(VI)O4 compounds. This suggests that it is also possible to synthesize CrO2 by reacting Cr(III) with Cr(VI) under appropriate conditions. Thus, metastable chromium dioxide (CrO2) powder was synthesized by mechanically grinding a mixture of CrO3 and Cr(OH)3 to induce a solid–solid reaction at atmospheric temperature and pressure. The characteristics of the product obtained after mechanical grinding of the above mixture depended on parameters such as the preparation conditions for the starting material Cr(OH)3, the grinding time, the rotational speed of the mill and the mole ratio of CrO3 and Cr(OH)3. An x-ray diffraction pattern of the product obtained under optimum conditions was in excellent agreement with the profile of CrO2. Furthermore, the powder was strongly ferromagnetic, with saturation magnetization of 63 emu/g in an applied field of 1 T.

Medium magnetizations for longitudinal high-density digital recordings

This paper reports on the influences of magnetic media remanent magnetizations on the output levels in digital magnetic tape and disk recording. While at low densities a high magnetization is required for a high output, a lower magnetization is required at high densities. However, for particular applications, an output near to the maximum can be obtained from a wide range of remanent magnetization values, which suggests possible uses for media with diverse properties.