Amount Of Tape Research Articles

Continuous, Ultra-lightweight, and Multipurpose Super-aligned Carbon Nanotube Tapes Viable over a Wide Range of Temperatures.

In extreme environments, such as at ultrahigh or ultralow temperatures, the amount of tape used should be minimal so as to reduce system contamination and unwanted residues. However, tapes made from conventional materials typically lose their adhesiveness or leave residues difficult to remove under such conditions. Thus, the development of more versatile, lightweight, and easily removable tapes for applications in such extreme environments has received considerable attention. Here, we report that horizontally superaligned carbon nanotube (SACNT) tapes can be used to provide perfect van der Waals (vdW) interface contacts over a wide range of temperatures (from -196 to 1000 °C), yielding outstanding adhesiveness with specific adhesion strengths up to ∼1.1 N/μg. With a surface density of only 0.5-5 μg/cm2, hundreds of times lighter than the vertically aligned CNT adhesives, the SACNT tapes can be cost-effectively provided in hundreds of meters. They have multipurpose adhesive abilities for versatile materials and are also easily separated from samples even after exposure to extreme temperature regimes. First-principles calculations confirm the mechanism of vdW adhesion and reveal that ultraflat and nanometer-thick SACNT tapes may yield far greater adhesive abilities. These SACNT tapes show great potential for use in mechanical bonding, electrical bonding, and thermal dissipation in electronic devices.

Round Conductor With Low AC Loss Made From High-Temperature Superconducting Tapes

The second generation of high-temperature superconductor tape exhibits rapidly progressing electric transport capacity. However, its use as a conductor in magnet technology is somewhat held up by the strip-like geometry. Possible solution is the helical layout of parallel tapes on a flexible round former (recently called the Coated Conductor on Round Core or CORC). We present the study of AC properties of single-layer CORC conductors made from tapes with non-magnetic substrate. When subjected to AC magnetic field, single-layer CORC conductors exhibit negligible coupling currents because the tapes are fully transposed. On top of this the hysteresis loss can be reduced by the tape striation. Numerical simulations of magnetization loss for CORC conductors are in good agreement with experimental data. Prediction of AC loss in a coil made from CORC is compared to that calculated for a classical double pancake one made from the same amount of tape. Result indicate that the CORC-made coil produces lower losses at AC current amplitudes approaching the critical current.

Magnetization of the stack of HTS tapes

New results of dependence of magnetic field, trapped by a stack of HTS tapes, on amount of tapes in a stack are reported. Commercial GdBCO tape 12 mm width and without Cu layer was used for the research. Tape was divided in square pieces 12 x 12 mm 2 from which stacks were formed. Filling factor of the tape was about 1.4%. Measurements were carried out for stacks with height from 5 to 250 pieces and at wide temperature range from liquid helium to liquid nitrogen. Both FC (field cooling) and ZFC (zero field cooling) cooling methods were used in the research. These two methods show matching results with good accuracy. As a result dependences of trapped magnetic flux on amount of tapes for different temperatures were received. Research shows, that with increasing height of the stack trapped magnetic field value reach saturation at about 60 tapes in a stack for low temperatures. From 60 to 100 tapes increase of magnet flux is only 5%. Thus increase amount of tapes in a stack is not profitable. Also investigation of trapped magnet field relaxation was carried out. Relaxation speed decreases with increasing amount of elements. It means that the higher the stack is, the longer trapped flux will be held in cause of the same temperature.

The Repack Challenge

Physics data stored in CERN tapes is quickly reaching the 100 PB milestone. Tape is an ever-changing technology that is still following Moore's law in terms of capacity. This means we can store every year more and more data in the same amount of tapes. However this doesn't come for free: the first obvious cost is the new higher capacity media. The second less known cost is related to moving the data from the old tapes to the new ones. This activity is what we call repack. Repack is vital for any large tape user: without it, one would have to buy more tape libraries and more floor space and, eventually, data on old non supported tapes would become unreadable and be lost forever. In this paper we describe the challenge of repacking 115 PB before LHC data taking starts in the beginning of 2015. This process will have to run concurrently with the existing experiment tape activities, and therefore needs to be as transparent as possible for users. Making sure that this works out seamlessly implies careful planning of the resources and the various policies for sharing them fairly and conveniently. To tackle this problem we need to fully exploit the speed and throughput of our modern tape drives. This involves proper dimensioning and configuration of the disk arrays and all the links between them and the tape servers, i.e the machines responsible for managing the tape drives. It is also equally important to provide tools to improve the efficiency with which we use our tape libraries. The new repack setup we deployed has on average increased tape drive throughput by 80%, allowing them to perform closer to their design specifications. This improvement in turn means a 48% decrease in the number of drives needed to achieve the required throughput to complete the full repack on time.

Digital Television Recording with Low Tape Consumption

It is anticipated that analog equipment now issued in studio centers and for transmission throughout the IBA network will be progressively replaced by equivalent digital equipment. This change, however, could not be envisaged until digital video recording was proved feasible. The essentially different characteristics of digital recorders are compared with those using analog techniques. This study considers the problems and requirements which arise in achieving high packing densities on magnetic tape and how these may be resolved to yield a digital recorder using about the same amount of tape as current analog broadcast-quality 1-in helical videotape recorders.

Turing machines with restricted memory access

Multitape Turing machines which can use their storage tapes only as counters or as pushdown stores are investigated. The memory access restrictions are produced by regarding the machines as small computers (as in the formalism of Wang) and by restricting the instruction repertoires. Relationships are given linking machines which only accept or reject inputs and machines which emit output sequences as a function of their input. It is shown that without restrictions on computing time or amount of tape used that only six distinct classes of sets of strings (languages) are produced by the above memory access restrictions.