Data storage

The effective access of raw data that has been saved in previous experiments is important for repetition of experiments and to avoid unnecessary calculations. Information that was proved to be useful can be saved and retrieved for later use with other data sets. It is usually recommended to store raw data (input data), descriptors, and query data in separate database entities. By separation of primary structure data, secondary data, and query data, a simple retrieval of a previous experiment as well as the use of already calculated descriptors is possible. 

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This is a double-channel flaw detector having their own microcomputer with 1 Mbyte memory to store data of the LMA and the LF channels for 800...2000 m of a rope under inspection. The instrument can be used in two modes as a tester for operative inspection or as a device for the inspection data storage. 

Pulsed-force mode AFM (PFM-AFM) is a method introduced for fast mapping of local stiffness and adliesion with lower required data storage than recording force-distance curves at each point on the x-y plane [115]. A sinusoidal or triangular modulation is applied between the tip and sample (either via lever or sample piezo) at a lower frequency than that of either the piezo or cantilever resonance frequency. Tip and sample then come... 

Titrations may be automated using a pump to deliver the titrant at a constant flow rate, and a solenoid valve to control the flow (Figure 9.5). The volume of titrant delivered is determined by multiplying the flow rate by the elapsed time. Automated titrations offer the additional advantage of using a microcomputer for data storage and analysis. 

By working with a preprocessor, data-storage requirements are reduced from approximately a million bits of information to about 300. 

Optical counters Optical crystals Optical data storage Optical device Optical devices... 

Ca is replaced by a rare-earth element, resulting in a distorted perovskite stmcture, which is essentially orthorhombic. Orthoferrites, studied extensively in the early 1970s as potential data storage materials based on magnetic bubble domains (10), have been largely replaced by the garnet materials (see... 

Nevertheless, the market in compact disc equipment is increasing, and computer data storage has expanded rapidly, as well as telecommunication by sateUite and the use of high frequency devices. 

Fig. 8. Holographic data storage experimental results photographs of holographic reconstmctions from a multiplexed hologram (51).

A most important element in computer technology is data storage. Progress in microelectronics, therefore, is directly linked to progress in data storage, that is the abihty to store large amounts of information in the smallest possible space, irreversibly or preferably reversibly. 

For data storage two types of memory are distinguished (/) main memory with moderate capacity (currentiy 4 x 10 bit in each element) and extremely short access time (<10 s), and (2) mass memory with very high capacity (>10 bit in each element) and moderate access time (>10 s). 

Photopolymers and photothermoplasts are mentioned only in connection with holographic data storage (see Holography). The classical method of optical data storage in silver haUde films (photographic film, microfiche technique) is not discussed (see Photography). 

In general, the commercially used optical data storage media deposit the information on disks or cards (two-dimensional data deposition. Table 1). Data storage systems, which store data in three and more dimensions are being developed. 

Table 1. Methods of Two-Dimensional Data Storage on Disks...

CD-XA (CD-extended architecture) is the standard for CD-ROMs for data storage and compressed audio recording (up to four hours music in HiFi-stereo quaUty). The definition of the CD-XA format is also put down in the extended Yellow Book. 

The principal use of CD-ROM and WORM disks is essentially substitution of data storage on paper or microfiche. Conservative estimates number the worldwide use for data storage by paper at 91%, microfiche at 4%, and in electronic media at 5%, of which 4% are magnetic and 1% optical media (18). CD-ROM is being used as an electronic counterpart to print media the WORM disk presents itself more and more as a substitute for paper to store archivable, forgery-proof documents. 

MO Media Summary. When compared to magnetic recording on hard disks, the advantage of MO data storage is the removabiUty of the disks and the high storage capacity (especially on multiplatter (juke-box) systems) whereas the access times have not yet been reached. 

Fig. 16. Maximum achievable signal-to-noise ratio (SNR) on read-out of different writable optical data storage systems as a function of the writing energy (laser power) (121). SQS = Organic dye system (WORM) PC = phase change system (TeSeSb) MO = magnetooptical system (GbTbFe). See text.

Photochromic Organic Dyes. Intensive investigations into this category of substances have led to numerous patent appHcations. Copper—phthalocyanine pigments, organic dyes based on cyanine (Ricoh, Pioneer), naphthochinone (Nippon Denki), and ben2othiopyrane (Sony) (123) have been described. They did not lead, however, to any commercial use. Surveys on the possibiUties of optical data storage with photochromic dyes can be found (124,125). 

The practical use of photochromic dyes as memory layers in erasable and rewritable data storage disks fails not only because of their physical limitations (lacking sensitivity, insufficient stabiHty, low number of cycles), but also because the diode lasers required for switching in the visible range (wavelength between 450 and 600 nm) and the uv-range (around 350 nm) are not available. 

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