A method and system are provided for the transmission and reception of a composite radio-frequency (RF) signal including a supplemental signal, preferably representing encoded digital information, together with an analog signal which represents monophonic analog audio in the AM-band. The analog monophonic component of the composite signal may be received by conventional AM-band audio receivers. In certain embodiments, the analog signal is a single-sideband large-carrier or vestigial-sideband large-carrier signal, and the composite RF signal includes a digital signal whose spectrum is substantially confined in one inner sideband. In other embodiments, a baseband digital signal is combined with an analog monophonic audio signal and transmitted in upper inner and lower inner sidebands using nonlinear compatible quadrature amplitude modulation (NC-QAM). Additional digital signals' spectrum occupies the lower outer and upper outer sidebands. In certain embodiments, for each transmitted codeword, part of the codeword information is replicated by modulated signals in both the upper outer and lower outer sidebands, preferably with diversity delay between the outer sideband signals.

There is a scarcity of contiguous amounts of available (unused) spectrum at those radio frequencies which are desirable for wide-coverage terrestrial broadcast communication systems in the high frequency (HF) band, between 3 megahertz (MHz) and 30 MHz, and especially in the low frequency (LF) band, between 300 kilohertz (kHz) and 3,000 kHz. In certain cases, the spectrum of certain conventional information-bearing signals does not entirely occupy a particular frequency allocation, and/or the existing signals may not utilize all of the signaling dimensions, for example, having only amplitude modulation or phase modulation, but not both at once. As a result, it is desirable to generate supplemental signals, especially digitally-encoded signals, in the unoccupied parts of existing bandwidth allocations and/or by making use of underutilized signaling dimensions in order to provide capacity for digital (bit) information in a manner that does not introduce significant amounts of interference to existing signals. The additional information capacity is used for the introduction of new broadcast services, for example, navigation and subscription messaging, and/or the enhancement of existing broadcast services, for example, digital audio broadcasting to provide recovered audio quality comparable to high fidelity tape and compact disc (CD) recordings.
In the United States, the commercial (expanded) AM broadcast band presently occupies a part of the LF band of frequencies between 535 kHz and 1705 kHz, inclusive. The frequency region is subdivided into a plurality of channel allocations with an interchannel frequency separation of 10 kHz (an interchannel frequency separation of 9 kHz allocations has been proposed). Licensed radio stations are subject to restrictions on permissible AM-band signal power, spectrum occupancy (i.e. bandwidth), and geographic location in order to control the expected amounts of interference between stations. Rules and regulations regarding the licensing and operation of AM-band stations are enacted and enforced by the Federal Communications Commission (FCC) in the United States. A restriction for AM-band sound broadcast signals is determined by the FCC "emissions mask". The emissions mask specifies a power spectrum density curve which defines the maximum allowable power of a discrete emission with respect to the licensed power as a function of the frequency offset from the nominal AM-band channel center frequency. Discrete emission compliance at a particular frequency is measured over a 300 Hz integration bandwidth.
Prior art FIG. 1 is a graph which illustrates an emissions mask for AM-band broadcast signals in the United States. The abscissa values are the frequency offset with respect to nominal AM-band channel allocation center frequency 1. The ordinate values are the decibel spectrum magnitudes with respect to the licensed modulated carrier power (dBc). The emissions mask is shown as bold curve 3. Conventional monophonic analog AM signal 7 is the modulated signal representation of the arithmetic sum L+R of the left (L) and right (R) conventional analog audio signals. Conventional monophonic AM signal 7 is substantially confined within, under, and/or beneath emissions mask 3. The center region of mask 3 includes upper inner 5 and lower inner 9 sidebands and occupies a two-sided bandwidth of about 20.4 kHz (i.e. 9.9 kHz+0.3 kHz+0.3 kHz+9.9 kHz) around channel center frequency 1. In the center region, the maximum emission power may be as large as the licensed power; in other words, -0 dBc. Outer sideband regions 13 and 11 are disjoint and immediately adjacent to inner sidebands 5 and 9, respectively, at positive and negative frequency offsets, respectively, with respect to center frequency 1. Upper outer sideband region 13 occupies 9.8 kHz, beginning at a positive 10.2 kHz offset and extending to a 20 kHz offset. Lower outer sideband region 11 also occupies 9.8 kHz, beginning at a negative 10.2 kHz frequency offset with respect to center frequency 1 and extending to a negative offset of 20 kHz. It will be understood by those of skill in the art that the bandwidth occupancies of sidebands 5, 9, 11, and 13 are to change.
In outer sidebands 11 and 13, the maximum power of a discrete emission is attenuated by at least 25 decibels with respect to the licensed power; in other words, -25 dBc. Conventional AM-band broadcasting uses large-carrier amplitude modulation so that a significant fraction of the RF signal power is emitted as the sinusoidal carrier component with center frequency 1. In many circumstances, analog signal 7 may be substantially confined in a spectrum region within inner sidebands 5 and 9, closer to a two-sided bandwidth of 14 kHz (.+-.7 kHz) than 20.4 kHz around center frequency 1, with outer sidebands 11 and 13 substantially unoccupied. There are additional sideband regions defined in emissions mask 3 which are not shown in FIG. 1, beginning at .+-.20 kHz with respect to center frequency 1, which extend significantly beyond outer sidebands 11 and 13.
Since the bandwidth of conventional monophonic AM signal 7 does not occupy all of the spectrum allocated in inner sidebands 5 and 9 and outer sidebands 11 and 13 within emissions mask 3, it is known that one or more supplemental information-bearing signals, preferably representing digital information, may be transmitted together with conventional monophonic analog AM-band signal 7, while still remaining substantially confined within emissions mask 3. When the generation of the supplemental signal is unrelated to conventional analog AM signal 7, the spectrum of the supplemental (i.e. digital) signal is typically confined to outer sidebands 11 and 13 in order to prevent mutual interference between the analog AM signal and the digital signal. In certain circumstances, when the digital signal is related to conventional analog AM signal 7, the spectrum of the digital signal may also include part of or the entirety of inner sidebands 5 and 9. In general, the sideband regions beyond (i.e. at greater frequency offsets than) upper outer 13 and lower outer 11 sidebands are unsuitable for use in broadcasting a supplemental digital signal which provides wide geographic coverage because i) the permissible amount of emitted power in these sidebands is very small, e.g. no more than -35 dBc, and ii) signals at a such a large frequency offset from center frequency 1 may be subject to (or cause) significant amounts of interference from (or to) stations with AM-band transmitters operating on adjacent frequency channel allocations.
In certain applications, it is known that the supplemental digital signal represents a compressed digital audio signal to accomplish the goal of improving the received quality of voice and sound transmissions for broadcasting in the AM-band. U.S. Pat. No. 5,588,022 to Dapper, et. al., describes an In-band On-channel (IBOC) Digital Audio Broadcasting (DAB) communication system for use in the AM-band. In the '022 system, a digital signal, preferably representing a source-compressed high quality audio signal, is combined with a conventional analog AM signal to determine a composite RF signal which is substantially confined within the FCC emissions mask for the AM-band. IBOC DAB makes use of the existing infrastructure of transmitter systems and does not disrupt the economic model for sound broadcasting in the United States. In the '022 system, the composite RF signal is transmitted using a conventional AM transmitter and antenna system so long as the transmission system has sufficiently low distortion and wide bandwidth. A graph representing the spectrum of the signals in the '022 system is shown in prior art FIG. 2, where the composite RF signal spans a bandwidth of 40 kHz and is the additive sum of digital signals generated in upper outer 13 and lower outer 11 sidebands, conventional large carrier analog AM signal 7, and upper inner 5 and lower inner 9 sideband digital signals. Each sideband digital signal is composed of a plurality of narrowband orthogonal sinusoidal subcarriers which are generated and summed together according to the known method of Orthogonal Frequency Division Multiplexing (OFDM), also known variously as Coded Orthogonal Frequency Division Multiplexing (COFDM), Multicarrier Modulation (MCM), and Discrete Multitone Modulation [reference: J. A. C. Bingham, "Multicarrier modulation for data transmission: an idea whose time has come," IEEE Communications Magazine, Vol. 28, No. 5, pp. 5-14, May 1990]. The narrowband subcarriers are each digitally modulated with either binary phase-shift keying (BPSK), quaternary phase-shift keying (QPSK), or 32-ary quadrature amplitude modulation (QAM).
In FIG. 2, groups of OFDM subcarriers are generated to occupy substantially all of upper outer 13 and lower outer 11 sidebands defined under emissions mask 3. These modulated subcarriers have both an in-phase and quadrature signal component with respect to conventional monophonic analog AM signal 7. In the center region of emissions mask 3, the OFDM subcarrier group in lower inner sideband 9 and the OFDM subcarrier group in upper inner sideband 5 are generated as complementary pairs (i.e. each subcarrier in group 5 has a corresponding subcarrier in group 9 with a predetermined phase relationship) so that the resulting composite signal for the inner sidebands has a linear phase-quadrature relationship (i.e. out-of-phase by 90.degree. or .pi./2 radians or positive or negative odd integer multiple thereof) to analog AM signal 7. As a result of the linear phase-quadrature relationship, the spectrum of the composite digital signal in the inner sidebands may substantially overlap in frequency the spectrum of conventional analog AM signal 7. In the '022 patent, conventional analog AM signal 7 is referred to as an I (in-phase) signal, and the composite inner sideband digital signal is referred to as a Q (quadrature) signal. The quadrature composite inner sideband digital signal is also attenuated with respect to the analog AM signal by a significant amount which varies according to each subcarrier in the composite. Since the composite inner sideband digital signal is phase-quadrature to the conventional analog AM-band signal, the two signals may be readily separated from each other in the corresponding receiver system in the absence of distortion using the known method of synchronous linear demodulation. In the '022 system, additional bit information is conveyed by OFDM digital signals generated to occupy upper outer 13 and lower outer 11 sidebands in addition to inner sidebands 5 and 9. However, unlike the composite inner sideband digital signal, the upper and lower outer sideband digital signals have both in-phase and quadrature signal components and are not phase-quadrature to conventional analog AM signal 7. In order to prevent mutual interference between the outer sideband signals and the analog AM signal, the outer sideband signals have to be substantially frequency-orthogonal to conventional analog AM signal 7. The outer sideband signals may be separated from the analog AM signal in the receiver system using bandpass filtering. The correlation processing used in the conventional demodulation of OFDM signals by the Fast Fourier Transform (FFT) mathematical algorithm inherently accomplishes some amount of bandpass filtering.
The premise that a supplemental signal can occupy the same spectrum as conventional analog AM signal 7 by generating the supplemental signal so that it is quadrature to the conventional analog AM signal was known prior to the '022 system, without consideration of whether such signal represents analog or digital information. Various such systems were developed for the application of analog AM-band stereo broadcasting. For example, the analog AM stereo system proposed by Harris [reference: F. G. Stremler. Introduction to Communication Systems. Reading, MA: Addison-Wesley Publishing Company, 2nd edition, appendix H, pp. 679-687] uses linear quadrature amplitude modulation (QAM) to generate two phase-quadrature signals which occupy the inner sidebands in AM-band emissions mask 3; see also U.S. Pat. No. 4,458,361 to Tanabe, et. al., and Y. Sakaie, et. al., "An amplitude-modulated stereo system", IEEE Transactions on Broadcasting, Vol. 26, No. 4, pp. 125-132, Dec. 1980. One of the signals is, or is related to, conventional monophonic L+R analog AM signal 7, and the other signal is, or is related to, an analog representation of the L-R stereo difference signal.
U.S. Pat. No. 4,688,255 to Kahn, describes a system in which a digital signal is generated to be phase-quadrature to the conventional analog AM signal. The digital signal is a narrowband phase-shift keyed (PSK) sinusoidal waveform, whose spectrum includes narrowband emissions at frequency offsets of about .+-.10 kHz from AM-band channel allocation center frequency 1. The spectrum of the digital signal in the '255 system does not significantly overlap the spectrum of the conventional analog AM signal so that compatibility with both monophonic and stereophonic analog AM-band signals is maintained. The amount of power in the transmitted digital signals is varied according to the analog signal power in order to minimize interference in the recovered analog audio signal. A disadvantage of the '255 system is that only a small amount of bandwidth is available for generation of the digital signal. Furthermore, reception of the digital signal is deleteriously affected in the first-adjacent interference circumstance because the upper or lower sideband signals may be substantially occluded, yet both sidebands are always combined in the '255 receiver system.
A known disadvantage of linear phase-quadrature methods for generating a supplemental signal to the conventional analog AM signal, whether representing analog or digital information, is that the existence of the quadrature signal causes distortion in the received and determined analog AM signal estimate in analog AM-band receivers which implement envelope detection. Envelope detection is widely implemented for the demodulation of monophonic analog AM signals because of its simplicity and low cost. Unfortunately, envelope detectors for demodulating monophonic analog AM signals are responsive to both the in-phase signal component, which is desirable when the in-phase signal component is the monophonic analog AM signal, and the quadrature signal component, which is undesirable when the quadrature signal component is the supplemental signal. In order to minimize the amount of distortion introduced by the quadrature signal for envelope detection receivers, the quadrature signal is typically either i) significantly attenuated when compared to the in-phase analog AM signal, as described in the Harris AM-band analog stereo system proposal, or ii) an envelope-correcting factor is introduced which affects to substantially cancel the distortion caused by the quadrature signal in envelope detection receivers, as described in the Motorola AM-band analog stereo system proposal [reference: F. G. Stremler. Introduction to Communication Systems. ibid.]. An advantage of the Motorola AM-band analog stereo system proposal is that the supplemental signal, which is the analog stereo difference signal, may be transmitted at a power level comparable to the monophonic analog AM signal. Comparable power levels are desirable so that the coverage provided by the analog AM stereo signal is similar to that provided by a conventional monophonic analog AM signal. However, the Motorola analog stereo system proposal requires a more complicated receiver system because the effect of the envelope-correction factor has to be removed in order to recover the stereo difference signal.
In the '022 system to Dapper, et. al., the deleterious effect of the quadrature composite inner sideband digital signal on conventional analog AM receivers with envelope detection is mitigated by the significant attenuation of the composite inner sideband digital signal when compared to the analog AM signal. This approach is similar to the Harris analog AM stereo system proposal although the specific method for accomplishing attenuation is different; in the Harris system, a phase offset is introduced between the quadrature signals. Under ideal RF propagation conditions, the low-power digital signal may be separated from the received composite RF signal, which also includes the high-power analog AM signal, with relatively small distortion to the recovered digital signal. However, when the RF propagation conditions are dispersive (e.g. frequency-selective with non-flat group delay) or the transmitter and receiver implementations have appreciable nonlinearities or dispersion, mutual interference between the analog AM signal and the digital signal in the '022 systems may be caused by "cross-talk"; in other words, the loss of the phase-quadrature relationship between the signals, also called the loss of "orthogonality". Since the analog AM signal has substantially larger power than the digital signal, a relatively small amount of crosstalk measured, for example, by equivalent phase error, may result in substantial interference from the analog AM signal to the recovered digital signal.
There are also disadvantages to the '022 system in circumstances where there are other operating AM-band transmitters with the same or similar allocation center frequencies. In order to convey a large amount of user source bit information (e.g. 96 kbit/sec) in a relatively narrow bandwidth (e.g. 40 kHz), the modulation method implemented in the '022 system has to provide for a very high user bit information density, between about 3 bits/Hz/sec and 5 bits/Hz/sec, depending upon the specific bit throughput requirements and the amounts of forward error correction (FEC) redundancy included with the user source bit information. Such high information densities require a relatively large signal-to-noise ratio (SNR) for adequate receiver operation at a sufficiently low bit error rate (BER), typically a BER of less than about 1.times.10.sup.-6 after error correction for digital audio applications. According to published laboratory data for an AM-band IBOC DAB system whose description is similar to that of the '022 system, impairment of the received digital audio signal occurs at a SNR ratio of 19 dB, which is quite large (a large required SNR is undesirable) [reference: "Digital Audio Radio; Laboratory Tests; Transmission Quality Failure Characterization and Analog Compatibility," published by Electronic Industries Association (EIA) Consumer Electronics Group (CEG), Digital Audio Radio (DAR) Subcommittee, Aug. 11, 1995, sections A, AI].
As described previously, the FCC Rules and Regulations act to restrict the power, bandwidth and geographic location of AM-band transmitters with similar allocation frequencies. These rules permit AM-band transmitters with the same channel allocation frequency (e.g. center frequency 1), known as co-channel transmitters, to be situated so that the ratio between desired and undesired signal energies, known as the "D/U ratio", at the edge of coverage for the desired transmitter's signal is only 20:1, which is 26 dB. According to the '022 patent, the power of each OFDM subcarrier in the digital signal is less than -25 dBc (excluding the two innermost subcarriers used for frequency-tracking only). Thus, at the edge of coverage, the interfering analog AM signal power becomes comparable to the digital signal power. Since a relatively large SNR (e.g. 19 dB) is needed for proper operation of the digital signal receiver, having comparable amounts of digital signal power and interfering analog signal power may cause digital receiver failure. As a result, the digital signal may not be reliably received except when the digital signal receiver is in close physical proximity to the desired signal's transmitter; in other words, the coverage of the digital signal is adversely affected when compared to the coverage of the conventional analog AM signal. Signal coverage over a wide area is important to minimize the number of transmitters needed to provide sufficient signal strength over a particular geographic region. A primary goal of IBOC DAB systems, whether operating in the AM-band or the FM-band, is to provide digital signal coverage comparable to the corresponding analog signal coverage.
There are other interference circumstances where the effects of adjacent AM-band transmitters on the operation of the '022 system are even more deleterious than in the case of co-channel interference. Prior art FIG. 3 is a graph which illustrates a circumstance where there is an operating AM-band transmitter under the first-adjacent circumstance. This occurs for (interfering) transmitters with allocation center frequencies at a positive or negative 10 kHz offset from center frequency 1 of the desired transmitter's signal. In FIG. 3, a first adjacent interferer is shown with positive offset center frequency 19, but the choice for illustration purposes is arbitrary. According to FCC Rules and Regulations, for an analog AM receiver located at the edge of coverage for the desired signal, the amount of interfering power in the received signal due to a possible first adjacent AM-band transmitter may be as much as one-fourth (i.e. a D/U ratio of 6 dB) as the desired signal's power. A more optimistic circumstance is shown in FIG. 3, which corresponds to a situation where the receiver is closer to the desired signal's transmitter. The spectrum of interfering analog AM signal 21 significantly occludes both upper inner 5 and upper outer 13 sideband regions in the spectrum of the desired signal, so that reliable determination of unique information in each of these sidebands may not be possible. Lower outer sideband 11 is substantially unaffected. When the interfering transmitter also emits an IBOC DAB signal according to the '022 patent, there may also be interference between lower outer digital sideband 23 of the interfering signal and lower inner digital sideband 9 of the desired signal. FIG. 3 shows only one first-adjacent interferer. In general, there may zero, one, or two or more first-adjacent interferers. However, the probability of two or more first-adjacent interferers causing large amounts of interference at a particular receiver location within the expected coverage of the desired analog AM (and supplemental digital) signal is small. According to the previously referenced EIA CEG DAR laboratory test report, an AM-band IBOC DAB system similar to that described in the '022 patent exhibited impairments in the recovered digital audio signal when the D/U ratio was as high as about 31 dB (.about.35:1) with digital receiver system failure (i.e. muting) at a D/U ratio of about 28 dB. Thus, even a small amount of first-adjacent interference may cause appreciable degradation of the receiver performance in the '022 system.
Prior art FIG. 4 shows an interference circumstance known as second-adjacent interference. Second-adjacent interfering AM-band transmitters are located at frequency offsets of positive 20 kHz and/or negative 20 kHz from desired transmitter's allocation center frequency 1. FIG. 4 shows one interferer at positive 20 kHz offset 27, but in general, there may zero, one, two, or more second-adjacent interferers situated at positive and negative 20 kHz offsets. FCC Rules and Regulations permit the interference power to be about equal to the desired signal power (D/U is 0 dB or 1:1) at the edge of coverage for the desired signal. For the second-adjacent circumstance in FIG. 4, the spectrum of interfering analog AM signal 37 occludes a substantial part of the spectrum of upper outer sideband 13. Correspondingly, the analog AM signal of a second adjacent interferer at a frequency offset of -20 kHz (not shown) would occlude part of lower outer digital sideband 11. If the interfering transmitter also emits an IBOC DAB signal, lower outer digital sideband 38 of the interfering transmitter's signal spectrum substantially occludes upper inner digital sideband 5 of the desired signal's spectrum. According to the EIA CEG DAR laboratory test report, an AM-band IBOC DAB system similar to that described in the '022 patent exhibited impairment of the recovered digital audio signal at a D/U ratio of about 31 dB. In other words, the performance of the digital signal receiver was significantly impaired with an amount of interference that is approximately 35 times weaker than the amount of interference permitted by the FCC Rules and Regulations at the edge of coverage. Thus, the potential coverage of the '022 system is made substantially smaller than the corresponding coverage of the analog AM signal by the presence of adjacent channel AM-band transmitters, which is undesirable. In both the first adjacent and second-adjacent circumstances, the outer digital sidelobes may also cause interference to the recovered conventional adjacent-channel analog AM signal because of the spectrum overlap.
Various methods other than phase-orthogonal linear quadrature amplitude modulation (QAM) for generating a supplemental signal were investigated for the purpose of compatible analog AM-band stereo broadcasting. A proposal by Kahn/Hazeltine described a system in which the left (L) and right (R) conventional analog audio signals are represented by independent upper and lower inner sidebands within the inner sidebands of the emissions mask [reference: F. G. Stremler. Introduction to Communication Systems. ibid.]; see also U.S. Pat. No. 4,589,127 to Loughlin, U.S. Pat. No. 4,124,779 to Berens, et. al., and U.S. Pat. No. 4,569,073 to Kahn. In the Kahn system, the lower inner sideband is the single-sideband modulated representation of the left audio signal and the upper inner sideband represents the single-sideband modulated representation of the right audio signal, or vice versa. Prior art FIG. 5 is a graph which shows the spectrum of such an independent sideband method for analog AM stereo broadcasting. Unlike conventional analog AM signal 7 shown in prior art FIGS. 1-4 in which the analog signal sidebands are even-symmetric around center frequency 1, inner upper 33 (right) and inner lower 31 (left) analog signal sidebands in FIG. 5 are not symmetric, in general. However, it is known that when a conventional analog AM signal receiver is tuned to center frequency 1, then the monophonic (L+R) audio signal recovered in the receiver by envelope detection will be approximately equal to the monophonic audio signal recovered from conventional analog AM signal 7. The implementation of analog AM stereo broadcasting according to the Kahn/Hazeltine system precludes the generation of a supplemental digital signal in the upper inner or lower inner sidebands because all available signaling dimensions are utilized, and there is substantially no unoccupied bandwidth.
Prior art FIG. 6 shows the spectrum of an analog signal according to the Motorola method of compatible quadrature amplitude modulation, which is known by the trademark C-QUAM, for analog audio stereo broadcasting in the AM-band; see also M. Temerinac, et. al., "MF-AM stereo broadcasting: the choice of modulation," IEEE Transactions on Broadcasting, Vol. 25, No. 1, pp. 79-87, March 1989. In a C-QUAM.TM. analog AM-band stereo system transmitter, the analog audio stereo difference L-R signal and analog audio stereo sum L+R signal (i.e. the monophonic audio signal) are first modulated with quadrature amplitude modulation (QAM). The resulting signal is processed by an amplitude-limiter to remove amplitude variations in the resulting signal, and the amplitude-limited signal is subsequently amplitude-modulated by the analog audio stereo sum signal L+R. The presence of the amplitude-limiter results in a nonlinear method of modulation. The resulting signal's bandwidth, as determined by the spectrum occupancy of exemplary C-QUAM.TM. upper sideband 32 and C-QUAM.TM. lower sideband 34 in FIG. 6, is greater than when a substantially linear method of modulation, such as conventional amplitude modulation (AM) or quadrature amplitude modulation (QAM), is implemented. An advantage of the C-QUAM.TM. method for analog audio stereo broadcasting in the AM-band is that the composite RF signal is compatible with envelope detection receivers even when the audio stereo difference and audio stereo sum signals are of comparable magnitude.
The described prior art '022 and '255 systems for generating a supplemental digital signal which is compatible with AM-band analog broadcasting have the disadvantage of a smaller potential coverage when compared to conventional analog AM signals due to external interference caused by co-channel and adjacent channel AM-band transmitters. The prior art '022 system is also susceptible to self-interference due to cross-talk under dispersive RF propagation conditions because of the disparity in analog AM and digital signal power and the substantial overlap in frequency between the analog and digital signals in the inner sidebands. Accordingly, it is apparent from the above that there exists a need in the art of AM-compatible digital broadcasting for: (i) generating a supplemental digital signal which has sufficient bit information throughput for applications such as digital audio broadcasting; (ii) generating a supplemental digital signal whose reception is robust against the effects of frequency-selective distortion and adjacent channel interference; (iii) generating a supplemental digital signal whose reception is robust against the effects of cross-talk under non-ideal RF propagation conditions; and (iv) generating a supplemental digital signal with improved compatibility for analog AM-band receivers with envelope detection.

AM-compatible digital broadcasting method and system


An ink composition includes an oil-based ink and a heat decomposition gas-developing agent that generates gas by a relatively small amount of heat. A thermal printer using the ink composition is not clogged with the composition even after a long-term storage, and provides a printed matter having excellent water resistance. Thus, the ink composition is remarkably useful for a thermal ink jet printer and a thermal ink permeation printer.

The present invention relates to an ink composition useful for a thermal ink jet printer or a thermal ink permeation printer, particularly to such that generates gas by relatively small amount of heat, and that causes no clog of nozzles of a thermal printer even after a long-term storage.
Thermal ink jet printers and thermal ink permeation printers have been well known as thermal printers that eject ink to a recording medium by heating. In the thermal printers, the ink is heated by heating elements to generate gas, thereby increasing an inner pressure of an ink fountain. According to the thermal ink jet printers, the ink is jetted by the increased inner pressure through nozzles onto a recording sheet, to provide an image on the sheet. According to the thermal ink permeation printers, the ink permeates through a porous film disposed between a thermal head and a recording sheet by the increased inner pressure, to provide an image.
Thus, the thermal printers eject the ink to a recording medium by gas-development from the ink, whereby the ink is required to generate gas by small amount of heat. Conventionally, aqueous inks having a low boiling point obtained by dissolving a water-soluble dye in water or in a mixed solvent of water and a hydrophilic solvent have been mostly used as the ink for the thermal printers.
The aqueous inks have advantage of generating gas by relatively small amount of heat. However, in the thermal printer using the aqueous inks, water composing the inks is often vaporized to provide a dried dye. The dried dye causes clog of nozzles of the printer, whereby the printer must be periodically cleaned. In such a case, because it is difficult to arrange a plurality of nozzles in one direction to form a line head, the thermal printer generally exhibits a low printing speed. Further, a printed matter obtained by such aqueous inks is poor in water resistance, so that deterioration such as stain of a printed image is caused by water.
Accordingly, an object of the present invention is to provide such an ink composition for a thermal ink jet printer or a thermal ink permeation printer that generates gas by relatively small amount of heat, that causes no clog of nozzles of a thermal printer even after a long-term storage, and that provide a printed matter excellent in water resistance.
As a result of intense research in view of the above object, the inventors have found that an ink composition as mentioned above is obtained by adding a heat decomposition gas-developing agent (blowing agent) to an oil-based ink. The present invention has been accomplished by this finding.
Thus, an ink composition of the present invention comprises: an oil-based ink composed of an organic solvent, and an oil-soluble dye and/or a pigment dissolved or dispersed in the organic solvent; and a heat decomposition gas-developing agent that is decomposed by heating to a decomposition temperature thereof to generate gas. Although conventional ink compositions using a nonvolatile solvent generally have a high boiling point, the ink composition of the present invention exhibits an apparent boiling point reduced by the heat decomposition gas developing agent. The heat decomposition gas-developing agent is decomposed to generate N2 gas, etc. by heating, whereby the ink composition of the present invention is ejected by a relatively small amount of heat, to be useful for the thermal ink jet printer or the thermal ink permeation printer. Further, when a preferred nonvolatile solvent is used as the organic solvent composing the oil-based ink, the nozzles of the thermal printer are not clogged with the ink composition even after a long-term storage, whereby above-mentioned periodical cleaning is simplified or omitted.

Ink composition for thermal ink jet printer or thermal ink permeation printer


A gate in a semiconductor device is formed to have a dummy gate pattern that protects a gate. Metal lines are formed to supply power for a semiconductor device and transfer a signal. A semiconductor device includes a quad coupled receiver type input/output buffer. The semiconductor device is formed with a gate line that extends over an active region, and a gate pad located outside of the active region. The gate line and the gate pad are adjoined such that the gate line and a side of the gate pad form a line. Dummy gates may also be applied. The semiconductor device includes a first metal line patterns supplying power to a block having a plurality of cells, a second metal line pattern transferring a signal to the cells, and dummy metal line patterns divided into in a longitudinal direction.

The present invention relates generally to a semiconductor device, and more particularly to a method of forming a gate of a semiconductor device, the gate having a dummy gate pattern that protects a gate pattern, a method of forming a metal line that supplies the power for a semiconductor device and transfers a signal, and a semiconductor device including a quad coupled receiver type input/output buffer.
In general, a typical semiconductor device includes devices such as transistors, capacitors, and resistors, and is formed with wirings that electrically connect the devices to one another.
When designing a semiconductor device, the electrical properties, the process influence, and the structural liability of the devices and the wirings should be ensured. More particularly, as a semiconductor device becomes highly integrated, the importance of the pattern and the layout of both the device and the wiring tends to increase.
Further, it is important to consider the gate pattern of MOS transistors when designing the device. The gate of the MOS transistor includes a gate line and a gate pad that are integrally connected to each other. Herein, the gate pad is a portion laid out so that a gate line and a metal layer overlap, and the gate line and the metal layer are electrically connected via a gate contact. Typical the gate pad has a rectangular shape and takes an overlap margin into consideration.
FIG. 1A is an example of a typical gate pad in a MOS transistor of a general semiconductor device. A gate line GL is formed over an active region 10, which constitutes a MOS transistor region, and a gate pad 12 is formed at the end of the gate line GL. Contacts BLC1 that constitute a source and a drain are formed over the active region at both sides of the gate line GL, and contacts BLC2, which are electrically connected to a metal line (not shown) at an upper portion thereof, are formed over the gate pad 12.
Herein, the gate pad 12 is laid out such that a side thereof adjoins an extended end of the gate line GL with a step.
FIGS. 1B and 1C illustrate a MOS transistor formed with at least two gates over the same active region 10. The gate lines GL have different lengths and each gate pad 12 is laid out such that a side thereof adjoins an extended end part of the gate line GL with a step. Also, each gate pad 12 is laid out in the same direction as the gate line GL to which the gate pad 12 adjoins.
The gate pattern in FIGS. 1A through 1C has an advantage in that the layout area is reduced as wiring connections between MOS transistors are minimized in a layout structure as shown in FIG. 2.
FIG. 2 illustrates a case where MOS transistors are used to construct a single circuit. Herein, a semiconductor device may have a structure that utilizes the same type of MOS transistor and arranges the MOS transistor in a line in one well region 22 defined by an active guard 20.
Each gate pad 12 is connected to the corresponding gate line GL by adjoining the gate pad 12 to the corresponding gate line GL (as in MOS transistor TR1) or by disposing the gate pad 12 at an area outside of an adjacent transistor's active region 10 and extending a portion of the side thereof (as in transistor TR2). Also, each active region 10 is irregularly disposed in the well region 22 according to the connection relationship between the MOS transistors (such as the transistors TR1 and TR2).
When the transistors TR1 and TR2 are disposed as in FIG. 2, the length of connection wiring can be minimized when connected to a drain (or a source) region of the transistor TR1 and a gate of the transistor TR2.
However, in the case of FIGS. 1A through 1C and 2, the gate of each transistor has many critical points, i.e. right-angled corners at portions where the gate line and the gate pad are connected. The critical points can cause a reduction in the process margin and an increase in the resistance due to the layout. Thus, the circuit properties of the transistor are lowered.
Additionally, if the active regions 10 are disposed irregularly (as shown in FIG. 2) in order to minimize the wiring connection between the transistors, the distances 'GT1'-'GT4' between the gate pad region 12 of each transistor and the active guard 20 are different, and the distances 'AT1'-'AT2' between the active region 10 of each transistor and the active guard 20 are different.
Additionally, spaces 'a', 'b', and 'c' between the gates of the adjacent transistors are different. Therefore, the line width of the gate of the transistor may vary as a difference of mass of the gate. Such a variation in the line width of the gate may cause changes in the electrical characteristics of the transistor, and a problem is caused in that it is difficult to operate an optical proximity correction for ensuring a uniform variation in the line width.
Meanwhile, when designing the wiring that includes the gate, it is important to ensure physical and electrical stabilities.
Referring to FIG. 3, in a general semiconductor device, a plurality of block cells BC1 through BC4, which are formed by a gathering of unit cells UC in a peripheral region, is disposed. Power metal line patterns 1 for supplying a power voltage VDD and a ground voltage VSS to each block cell BC1 through BC4 are disposed in parallel to each other, and signal metal line patterns 2 for transferring a routing signal between the block cells are irregularly disposed.
In a process of forming the aforementioned power metal line patterns 1 or signal metal line patterns 2, a chemical mechanical polishing process for formation of an oxide layer and planarization is performed after the formation of the metal line patterns 1 and 2.
However, as shown in FIG. 3, when the spaces between the metal line patterns 1 or 2 are different from one another, a dishing phenomenon can occur in a region having a low pattern density due to a planarization process used to etch metal. Therefore, a problem exists, in that it is difficult to ensure the stability of the metal line pattern when the metal line patterns are laid out as shown FIG. 3.
In order to ensure the stability of the metal line pattern, dummy metal line patterns 3 may be disposed between the metal line patterns 1 and 2 as shown in FIG. 4, which corresponds to FIG. 3.
In the case of FIG. 4, the dummy metal line patterns 3 disposed between the metal line patterns 1 and 2 are formed in a bar type parallel to the longitudinal direction of the metal line patterns 1 and 2. Also, dummy metal line patterns 3 have a predetermined width W defined as a design rule and a length L corresponding to a length of adjacent metal line pattern 1 or 2.
However, in the case of FIG. 4, a defect can occur when a particle P forms a bridge between the metal line pattern 1 or 2 and the dummy metal line pattern 3.
Meanwhile, when designing the wiring, it is also important to consider the electrical characteristics of the MOS transistor.
An input/output buffer of a semiconductor device having the MOS transistor should be designed so as to have a strengthened noise characteristic for a fast response characteristic. Also, the power line used in the input/output buffer should be designed so that the power line is not influenced by noise.
In a semiconductor device operating at a high speed, a quad coupled receiver type input/output buffer having a differential amplification structure that compares and amplifies a reference voltage VREF and an input signal IN as shown in FIG. 5 is mainly used.
In the quad coupled receiver type input/output buffer having the differential amplification structure, the electrical characteristics of the two MOS transistors <M11, M21>, <M12, M22>, <M31, M41> and <M32, M42> that form a differential pair or a current mirror should be the same for normal differential amplification.
However, the circuit construction causes the channel lengths of the MOS transistors to be different from one another, and as such the electrical characteristics of each MOS transistor may be different from the expected characteristics when the MOS transistors having different channel lengths are disposed adjacently as shown in FIG. 6.
Specifically, the MOS transistor pair M12 and M22 and the MOS transistor pair M32 and M42 are aligned in a sequence of 'M12, M32, M22, M42' as shown in FIG. 6. MOS transistors TR1 and TR2 are disposed at a side of the MOS transistor M12 and at a side of the MOS transistor M42 respectively.
The patterns between the active regions of the MOS transistors are gate dummies GD. The MOS transistors TR1 and TR2 of FIG. 6 correspond to the MOS transistors M5, INV1, and INV2, which do not require the same electrical characteristics, in the input/output buffer of FIG. 5.
As shown in FIG. 6, the MOS transistor pair M12 and M22 and the MOS transistor pair M32 and M42 having different channel lengths are alternately disposed. The gate dummy GD is disposed between the MOS transistors in order to minimize a variation in the gate critical dimension of the gate G.
However, since MOS transistors TR1 and M32 having different channel widths are disposed on both sides of a MOS transistor (for example, M12), the gate critical dimension of the gate of the MOS transistor M12 varies even though the gate dummy GD is disposed between the active regions.
In other words, when the channel widths of the adjacent MOS transistors are the same, the MOS transistors can have the electrical characteristics intended by the designer, since the pattern of the gate G of the MOS transistor is not changed as shown in FIG. 7A (distances A1 through A3 between a side surface of the gate and a contact are all the same).
However, when the channel widths of the adjacent MOS transistors are different, the MOS transistors may have electrical characteristics different from those intended by the designer, since the pattern of the gate G of the MOS transistor is changed as shown in FIG. 7B (distances B1 through B3 between a side surface of the gate and a contact are different).

Semiconductor device and method of forming gate and metal line thereof with dummy pattern and auxiliary pattern


The present invention relates to an improved process of analytical and quantitative isolation of withaferin-A from Withania somnifera (Sanskrit: Ashwagandha, English: winter cherry) and other plants and products therefrom, said method comprising steps of selecting most appropriate extraction medium composition, with extraction solvent system consisting of a defined admixture of water and alcohol in a range of proportion of alcohol within a narrow range of (methanol, ethanol etc.) (preferably 60% alcohol and 40% water) for the dry plant material and from 60% to 80% alcohol in the alcohol-water mixture for fresh plant material, the invented extractant composition leading to better/improved yields and accurate quantitative estimations of withaferin A existent in planta or in materia, selecting effective state of the tissue particularly use of the fresh materials improving yields, providing logistic benefits of isolations and diagnosis, and according several other advantages including technological, economic, preventing contaminations etc., the said method being valuable and advantageous for standardization of botanicals, metabolomic characterization of plants particularly chemotypes, analyzing metabolic transitions under physiological, genetical, environmental and biotic perturbations.

Ashwagandha is one of the most valuable medicinal plants, forming the active component or whole of the phytopharmaceutical products for the prevention and cure of a variety of human ailments and diseases. Numerically, Ayurvedic, Unani and Sidha medicinal products based on the plant currently run above one hundred and it is rapidly expanding worldwide. The plants, plant parts, crude extracts and other phytomatrices/preparations of ashwagandha are often sold on the basis of withaferin-A, besides the prepondrance of withanolides on the whole. Increasing evidences suggest that different withanolides are associated with different levels of pharmaco-efficiencies directed towards different ailments. Withaferin-A is one of the most pharmacologically active constituents. The emerging global trends in herbal products not only emphasize on better-descript and specific lable claims but also assert stringencies of compliances of regulatory frameworks like compliances like DSHEA, NHPR and other analogous regulatory acts and statutes. To cater to these and other needs, Therefore, appropriateness of the methodolocal processes for extractions described herein is not only of tremendous importance for the better and improved yields, resource characterization and accurate quantitative estimations existent in planta or in material, but also provides benefits and logistics of isolations, diagnosis, metabolomics etc. The process is valuable and advantageous in global scale of applications and relevance for standardization of ashwgandha botanicals, metabolomic characterization of plants, chemotypes, analyzing the nature and pace of metabolic transitions under physiological, genetical, environmental and biotic perturbations etc.
Withanolides or withasteroids are a group of naturally occurring C28-steroidal lactone molecules of basically triterpene ancestory and are structurally based on an intact or rearranged ergostane framework. The characteristic lactone is formed through conjoining of C22 hydroxyl and C26 carboxylic acid function. Thus, chemically withanolides are defined as 22-hydroxy ergostane-26-oic acid 26,22-lactone. Biogenesis of withasteroids is known to occur highly scarcely like Tacca plantaginea of Taccaceae (Z. L. Chen, B. D. Wang and J. H. Shen, 1988, Phytochemistry 29, 2999), Cassia siamae of Leguminoseae (C. Srivastava, I. R. Siddiqui, J. Singh and H. P. Tewari, 1992, J. Ind. Chem Soc. 69, 111), Ajuga parviflora of Labiatae (P. M. Khan, S. Ahmad, H. Rubnawaz and A. Malik, 1999, Phytochemistry, 51, 669; P. M. Khan, S. Ahmad and H. R. Nawaz, 1999, J. Nat. Prod. 62, 1290; H. R. Nawaz, A. Malik, P. M. Khan and S. Ahmad, 1999, Phytochemistry, 52, 1357) beyond their usual species limited prodigal producers i.e. 16 out of 96 genera of potato family (Solanaceae). These include, besides the well known Ayurvedic, Sidha, and Unani medicinal plant, Ashwagandha (winter cherry, Withania somnifera), Lycium, Datura, Iochroma, Physalis, Tubocapsicum, Solanum etc. Most of these plants are valued and/or used as: herbs or health foods and/or medicinal plants (based on the traditional knowledge of their positive support to body functions and responses), healing and healthful materials (as such or in the form of supplements, nutraceuticals, concoctions, formulations and compositions) althrough individual's age of growing and graying, rejuvenating and as remedial herbal products of acceptance, source of valuable phytoceuticals/phytochemicals with potentials of lead multifunction drugs/nutraceuticals of near future. Withaferin-A (ergostanically named as 4β, 27-dihydroxy-5β, 6β-epoxy-1-oxowitha-2,24-dienolide), the first member of this group of compounds was isolated from the well known Indian medicinal plant Ashwagandha (P. A. Kurup, 1956, Antibiotic principle of the leaves of Withania somnifera, Current Science, India, 25: 57) and its structure elucidated in 1965 (D. Lavie, E. Glotter and Y. Shvo, 1965, Constituents of Withania sonmifera Dun—the structure of withaferin A, J. Chem. Soc. 7517). Besides it is known to occur as one of the major withanolides in other Withania species (W. aristica, W. coagulans, W. futescens), Acnistus arborescens, Iochroma coccinium, Physalis viscosa. Withanolides are known to possess diverse biological and pharmacological activities. Particularly, withaferin-A, has several hard evidences, established through prolific studies of modern and state of the art research approaches of both in vivo and in vitro kind, of having valuable and a range of pharmacological activities including antibacterial (S. Chatterjee and S. K Chakraborty, 1980, Antimicrobial activity of some antineoplastic and other withanolides. Antonie van Leeuwenhoek 46, 59), cytotoxicity of KB cell cultures, inhibition of Sarcoma 180 and Walker intramuscular carcinosarcoma 256 tumors (S. M. Kupchan, W. K. Anderson, P. Bollinger, R. W. Doskotch, R. M. Smith, J. A. S. Renauld, R. H. K. Schnoes, A. L. Burlingame and D. R. Smith, 1969, Tumor inhibitors-active principles of Acnistus arborescens, Isolation and structural and spectral studies of withaferin-A and withacnistin, J. Org. Chem. 34: 3858), retardation of Ehrlich ascites carcinoma, arresting human larynx carcinoma cells at metaphase (B. Shohat, 1973, Antimitotic properties of withaferin-A and Ehrlich ascite tumor cells-cytological observations, Int. J. Cancer 5, 244), immunoactivation (B. Shohat, 1973, Antimittic properties of withaferin-A and Ehrlich ascite tumor cells-cytological observations, Int. J. Cancer 5, 244; M. Ziauddin et. al. 1996, Studies on the immunomodulatory effects of Ashwagandha, J. Ethanopharmacology, 50, 69–76), immunosuppression through inhibition of adjuvant arthritis and the graft versus host reaction (A. Fugner, 1973, Hemmung immunologisch bedingter entzundungen durch das pflanzensteroid withaferin A, Arzneim. Forsch 23, 932), cancer chemoprevention through selective inhibition of cycloxygenase-2 (B. Jayaprakasam and M. G. Nair, 2003, Cyclooxygenase-2 enzyme inhibitory withanolides from Withania somnifera leaves, Tetrahedron 59, 841–849), attenuation of tachyphylaxis to clonidine on electrically stimulated ileum in vitro (H. Matsuda et al., Structures of withanosides I, II, III, IV, V, Vi and VII, new withanolide glycosides, from roots of Indian Withania somnifera Dunal and inhibitory activity for tachyphylaxis to clonidine in isolated guinea-pig ileum, Bioorg. Med. Chem. 9, 1499–1507, 2001). It has also been suggested to be useful in cognitive dysfunctions and cause noortropic effects [J. N. Dhuley, 2001, Noortropic-like effect of Ashwagandha (Withania somnifera) in mice].
One of the most prolific producer plant, Withania (Ashwagandha in Hindi and Sanskrit, winter cherry in English) is the best source of withanolides particularly withaferin-A and has been recognized as a plant with multiple forms of medicine in Ayurveda, the most descript and extensive and one of the major Indian systems of traditional medicines. Currently, besides several forms of pure herbs and herbal extracts of Withania sold all over the world as herbal health helping GRAS (generally regarded as safe) products, Ashwagandha forms active ingredient of more than 100 Ayurvedic medicines, more than 30 Sidha medicines and a good number of Unani medicines.
It is well accepted that non-nutrient secondary metabolites form the basis of pharmacological value of these medicinal herbs. Thus, withanolidal phytochemicals like withaferin-A abundant and characteristic in Withhania and other producer plants are present day molecular medicinals avowal to the clinical significance of the plant and plant parts discerned in traditional medical practices. Thus, high yield isolation of withaferin A for various experimental, industrial and therapeutic utilities is of obvious importance. Furthermore, precision of dose of active ingredient is of fundamental and vital importance in any acceptable present day clinical practice. Accordingly, accurate estimation of its content, upto closest precision of its occurrence in planta or in materia is important to administer qualified dose(s) and ascertain/relate it to quantified effect(s). For these reasons, inter alia, quantitatively near to entirety of extraction are necessitated at both mass scale production and diagnostic analyses. In summation, efficient, effective and economical extraction/recovery of withaferin-A, as a process, is of tremendous importance to industrial, pharmacological, medicultural, analytical and allied clinical and agri-biotechnological and corporate interests.
Thus, this technological process invention draws its importance as relevance to one of the most critical requirement in the relevant withaferin-A based/centred trade and treatments whether as producer plant or plant part biomass or as products themfrom with the core concern of the quantitative isolation of withanolidal component of withaferin-A in the material of test and/or interest.
Although, some general protocols for post-harvest processing of plant materials of Withania species and other plants/plant parts containing withanolides have been adopted and described by a number of researchers interested in the digging out structural forms of the withanolidal molecules existing in the plant(s)/plant parts of interest from time to time. These methods teach most often than not harvesting of the material followed by shade drying of the material to fully de-aqueous state. The methods further teach that the dried materials be powdered and extracted with 100% methanol or 100% ethanol. However, these investigations have not attended the issue of differential extractability of specific withanolides in consonance with the considerations and cognizances of it being imposed by some structural traits, biogenetic and/or inter- and intracellular sequestration(s) etc. Even routine quantitative analyses carried out in the researches of the plant biological or biotechnological nature, have also been as such adopted from the protocols and processes of isolations taught by their chemical researchers counterparts, without assessing them in true analytical sense. To the best of our knowledge, there is no patent on any alternate or more effective or better in correctness or more precise in solvation and recovery of withaferin-A from holding materials nor any physical or biological state(s) etc. Alternative to dried material has ever been researched and requisitioned to invent a process for efficient isolation and accurately monitor quantitative abundance withaferin-A from the relevant plant materials and products therefrom. The methods for isolation of withaferin-A used so far have not been scrutinized to validate their efficiency as strictly defined relative concentrations/recoveries in numerical values. Accordingly, routinely for isolations and estimations of withaferin-A in the test plant or plant part or the tissue type obtained from the field or generated in vitro through culture techniques have been carried out by shade drying, powdering followed by extraction Soxhlet or sonication or microwave extraction in alcohol.
To the best of our knowledge, there is no patent advising a specific way of efficient isolation of withanolidal compounds from plant tissues for yields and/or quantitative diagnostics. In the U.S. Pat No. 6,153,198 Shibnath Ghosal advises that a Withania somnifera glycosides of withanolides (sitoindoisides) could be prepared by extracting root stock with an aqueous-alcoholic solvent (water-methanol or water-ethanol in 1:1 mixture i.e. 50% aqueous solution of alcohol.). The patent advises that this extract can be devoid of whatever withaferin-A that was co-extracted by further partitioning of the preparation with chloroform wherein chloroform preparation be discarded and chloroform insoluble part be processed for making the formulation with low levels of withanolides including withaferin-A.
Thus, the invented extraction process represents a case of exception to the foregoing fact pertaining to the quantitative extraction, recovery and quantitation of withanolides in the plant materials, extracts and preparations therefrom as they are actually present therein. Thus, extraction of withaferin-A in the literature so far has been quantitatively unevaluated to devise an extraction process that facilitates optimal quantitative recoveries and prevent under estimations due to sub-optimal extractions.
Furthermore, as a prior art only air or shade otherwise dried materials have been advised for isolating withaferin-A and then quantitating its amount in such an extract. This invention teaches the process of the fresh using fresh as well as dry plant materials to have full extractions. The use of fresh material avoids the degradative and/or metabolic transformation loss of withaferin-A during the course of such dessiccations. Such dessications may also accompany losses or recalcitrance to efficient extractions that lead to exacerbating errors in estimations and recoveries for quality control in biomass processing, manufacture, product formulation, cultivar evaluation and other diagnostics including those at the pharmacological and pharmacokinetic levels etc.
Besides attending the technical inaccuracies, as above in monitoring and yielding the withaferin-A from the resources when employing the routine methods taught by the published literature and other public domain documents, this invention saves several expenditures in the process for unit amount of withaferin A isolated.
Another concern not addressed by any disclosures in the open literature is the utility of processing fresh herbs for estimations in planta and other advantages associated with the process on account of that. These include better yields, estimations, saving time, space, and costs in drying, alteration in qualitative compositions, contaminations (environmental materials and inclusions particularly growth of microorganisms (molds, bacteria, fungi etc.) and insects and pests) and adverse effects due to them.
Thus, the industrial, economical and pharmacological, analytical and quality control related necessity of the process for economically extracting and estimating full quantitative amounts of withaferin-A from plant materials and products therefrom is quite obvious. This process has been invented in view of the still need for a process and procedure for isolating and purifying withaferin-A from appropriate biomass or material and medicaments in a commercially viable/valuable way for various established and other exploratory uses. Further, it is an analytically essentialilty that directly provides rightful recovery and evaluation of concentration of withaferin-A to from the basis of dose, does regimen and label claims of the products of commercial and pharmacological/clinical significance. Efficient extraction of herbs while preserving their medicinal values is a process art as well as biochemical science. Many extraction companies/groups/individuals might be delivering extracts of sub-optimal potency or compositional description—knowingly or unknowingly either because of lack of their prior experimental evaluation extraction process(s) and other reasons.
While literature describes some methods through which withaferin-A has been advised to be isolated from a plant or plant part [e.g. Dinan L. et al., 2001, 'Chromatographic procedures for the isolation of plant steroids' Journal of Chromatography A 935, 105–123, (see pages 118 and 119) advise that withanolides be generally extracted from plant material with methanol or ethanol which should then be depigmented by routine partitioning following mixing with water. The aqueous methanol phase then should be partitioned against chloroform or dichloromethane or diethyl ether to extract out the withanolides. The method does not advise anything like extent of efficiency when applied to specific withanolide including withaferin-A. A. S. Veleiro et al. (2, 3-dihydrojabrosalactone-A, a withanolide from Acnistus breviflorus, Phytochemistry 24, 1799–1802, 1985) isolated some withanolides including withaferin-A from methanolic extract of the dry herb. In another report on radiotracer based biosynthetic studies these workers (biosynthesis of withanolides in Acnistus breviflorus: biogenetic relationships among the main withanolides, Phytochemistry 24, 2573–2575, 1985). Ahmed et al. 'Withanolides from Physalis peruviana; Phytochemistry 50, 647–651 (1999) have used 95% ethanol as the extractant to visualize the presence of some known and unknown withanolides in the air dried plant material.
G. Roja et al. ['Tissue cultures of Withania somnifera: Morphogenesis and withanolide synthesis' Phytotherapy Research 5, 185–187 (1991) have used 100% methanol to extract withanferin A from dried cultured shoots and tissues to quantitate its concentration. Similarly, M. Furmanowa et al. [In vitro propagation of Withania somnifera and isolation of withanolides with immunosuppressive activity, Planta Med. 67, 146–149, 2001] have extracted air-dried green parts of the in vitro raised plants in 100% methanol or ethanol for recovery of withanolides including withaferin-A.
Very recently (2003) B. Jayaprakasam and M. G. Nair (Cyclooxygenase-2 enzyme inhibitory withanolides from Withania somnifera leaves, Tetrahedron 59, 841–849) have extracted shade dried and ground leaves of Withania somnifera sequential with dichloromethane-methanol (1:1), 100% methanol and then water to theoretically scope for extraction under three widely discrete polarities to probably qualitatively have as many withanolides as possible including water soluble glyco-derivatives of withanolides. Thus, no specific extractant system has been designed and evaluated for recovery of withaferin-A or other withanolide. No extraction has been made under a system of narrow range polarity available with water-methanol admixture was attempted or evaluated for recovery in a withanolide specific manner. J. Zhao and associates (Withanolide derivatives from roots of Withania somnifera and their neurite outgrowth activities, Chem. Pharm. Bull. 50, 760–765, 2002) have adopted a routine method of isolating and recovering withanolides including withaferin-A from the Withania herb by extracting the root powder with 100% methanol. In the same way, H. Matsuda et al. used 100% methanolic extract of Withania somnifera dried roots to isolate withanolides (including withaferin-A) and withanosides (Structures of withanosides I, II, III, IV, V, Vi and VII, new withanolide glycosides, from roots of Indian Withania somnifera Dunal and inhibitory activity for tachyphylaxis to clonidine in isolated guinea-pig ileum, Bioorg. Med. Chem. 9, 1499–1507, 2001). S. Ray and S. Jha (Production of withaferin-A in shoot cultures of Withania somnifera, Planta Med. 67, 432–436, 2001) have quantitated concentration of withaferin-A in Withania somnifera shoot cultures produced under different compositions of in vitro culture medium after extracting the dried biomass in 100% alcohol (methanol).
Thus, all prior arts of researches for extraction of withaferin-A, none has attended the relative extractability of withaferin-A in different extractant compositions to arrive at the optimal system. For such an analysis, it is prerequisite to have a specific experiment designed and executed to have a range of extractions made with an admixture of water and appropriate alcohol and to have a comparison of recoveries under such conditions using dry and fresh tissue in quantitative terms to invent the most appropriate one for yields and/or estimation of concentrations. No attempts have been made to address this issue and concern.
The focused microwave-assisted extraction experiments of Kaufmann et al. ['Parameters affecting microwave-assisted extraction of withanolides' Phytochemical Analysis 12, 327–331 (2001)] on withaferin-A from air dried Iochroma gesnerioides leaves, have assessed six variables viz. nature and volume of extracting solvent, sample moistening before extraction, extraction time, power of micro-wave irradiation and particle size. Their experiments concluded that for microwave extraction most favourable experiments were using powered material (as is usually done even in conventional extractions) previously moistened (600 microlitre per 100 mg dried material) helps improve microwave assisted extraction from the dry material to conceptually advise that the micro-waving in 100% methanol after moistening (as above) air dried leaves, helps in microwave-assisted methanol extraction (thus final extractant being about 95% methanol) of withanolides including withaferin-A because of better wave energy assimilation and promotion of cell disruption by internal superheating facilitating desorption of analytes from the matrix. The comparison has been made with conventional (soxhlet) extractions using 95% ethanol and 5% water. These workers, in another PSE instrumental extraction [Study of factors influencing pressurized solvent extraction, PSE, of polar steroids from plant material. ' Chromatographia 54, 394–398, 2001; 'Recent extraction techniques for natural products: microwave-assisted extraction and pressurized solvent extraction'. Phytochemical Analysis 13, 105–113, 2002) that a 1:1 mixture of methanol:water (i.e. 50% methanol) was useful in using pressurized solvent extraction (PSE) technology on air-dried leaf material. However, these revelations are related to operational parameters of the instrumental approaches of withanolide extractions rather than addressing the chemical characteristics/uniqueness of the molecules per se or in conjunction with their properties in biomass. Thus, serious concerns as how to appropriately extract withaferin-A in a solvent specific way as not been addressed nor the putative advantages of processing through the freshly harvested non-desiccated extractions, disjointed from the extraneous parameters of the instrumental mechanization or automation, has factually not been addressed.
Thus, it is clear that concerns like extractions from fresh herbs (for use in a variety of applications like resource authentication, quality assessment, metabolic, metabolomic and pathway analysis systems and devising post harvest technologies, avoiding drying times, space and money, man power and associated safety and contamination risks and hazards etc.) and use of suitably and stringently defined hydrated alcohol extraction with solvent/alcohol percentage narrowly gauged between 50% alcohol: 50% water to 100% alcohol: 0% water has not been worked out with respect to technological, diagnostic, productivity advantages in a withanolide specific way e.g. for withaferin-A. Additionally, it would offer wider ingenuousnesses e.g. in planta or in materia metabolome state for the withanolide. The approaches so devised have tremendous applications to boot accuracy of determinations and improved extractability with add on savings on several points at the bench level as well as at industrial scale in case of scale up strategies/systems, both in instrumentally unaided as well as mechanized/automate operation of the (agro)-chemical technology.

Process for isolation of withaferin-A from plant materials and products therefrom

Council of Scientific & Industrial Research


A metal vapor apparatus comprising a laser tube within which laser action occurs during operation of the apparatus, and means for applying a liquid metal coolant to the tube.

This invention relates to a laser apparatus and more particularly to apparatus in which metal vapour forms the laser amplifying medium.
Lasers which use metal vapour as the amplifying medium, for example copper or gold vapour, are, typically, of cylindrical geometry and require a high temperature to be maintained in the laser tube within which laser amplification occurs. This high temperature is necessary to maintain the metal vapour at a suitable operating pressure which is typically about one torr as a partial pressure within a buffer gas, which nay have any pressure up to hundreds of torr. For example, in a copper vapour laser, it is necessary to maintain the temperature within the laser tube at about 1600.degree. C. This type of laser may be termed a pure-metal high temperature (PMHT) laser. In presently available copper vapour lasers of the PMHT type, this is achieved by using thermally insulating material around the laser tube so as to reduce heat losses to a minimum and attain the high temperatures required.
Also, in copper vapour lasers, it is current practice to place the thermally insulating material and the laser tube which confines the discharge together within a vacuum envelope.
Thus, where high temperatures are required, there is a large amount of insulating material to be outgassed within the vacuum envelope. The nature and quantity of the thermally insulating materials used at the high temperatures involved make for excessively long outgassing times following exposure to the ambient atmosphere during routine service operations, such as reloading with copper and cleaning the laser windows.
The large amount of thermal insulating materials present both a large thermal capacity and a high thermal impedance, with the result that typical times required for a laser of average power for example, 20 Watts, to attain its operating temperature are about 60-90 minutes.
In another class of metal vapour laser, the amplifying medium is derived from a metal halide which vaporises to form a molecular gas of metal halide at lower temperatures than those required to produce comparable vapour pressures from a solid metal. This type of laser may be termed a metal-halide low temperature (MHLT) laser. When an electrical discharge pulse is passed through the metal halide vapour, the halide dissociates into metal atoms or molecules and halogen atoms or molecules. If a second discharge pulse is then passed before the metal and halogen atoms or molecules can recombine, the metal atoms may be excited to the same energy levels as those which participate in the PMHT laser. For example, in a copper vapour laser, copper bromide may be used. For copper bromide, temperatures in the region of 600-700 degrees C. are sufficient to produce the required partial pressures. However, although these temperatures are relatively low when compared to a laser in which the metal vapour is produced from solid metal, it is still common practice to provide a relatively large mass and volume of thermally insulating material around the laser tube to enable the system to be heated from room temperature to the operating temperature and also to ensure that at the operating temperature, power applied to the amplifying medium is available to the laser process.


The disclosure pertains to continuous-time filtering. More particularly, it relates to filtering in a feedback control loop, for example in a sigma-delta (ΣΔ) modulator. The making of a filter for this type of application comes up against a major problem linked to the relativity between the amplitude and phase responses. This limits the possibilities of choice in order to take steps against the instability of the loop. A continuous-time filter with minimum phase variation carries out the bandpass integration of the signal presented at its input. The making of the continuous-time filter as a bandpass integrator raises the problem of achieving a compromise between gain variations and phase variations close to the −1 critical point, This compromise must lead to the stability of the loop. This problem is resolved by using a continuous-time bandpass integrating filter comprising at least one resonance device with minimum phase variation.

1. Field of the Invention
The invention relates to continuous-time filtering. More particularly, it relates to filtering in a feedback control loop, for example in a sigma-delta (ΣΔ) modulator. Analog ΣΔ modulators can be used, for example, in radar receivers or telecommunications systems, in particular to improve the resolution of analog-digital encoding.
2. Description of the Prior Art
The ΣΔ modulation of a signal consists of the encoding of this signal on a small number of bits but with a far higher resolution than the theoretical limit given by the number of bits. To this end, a feedback control loop is made. The quantization device, which limits the resolution, is placed at output of this loop as can be seen in the generic diagram of FIG. 1(a).
If the signal is a digital signal, the ΣΔ modulator unit is made as a digital device. When the digital signal at the input of the ΣΔ modulator comprises N bits, the return signal comprises N bits including N−n null least significant bits (LSB), the input signal of the integration device 1 comprises N+1 bits, and the signal at the input and output of the quantization device 2 respectively comprises N bits and n bits (where n is far smaller than N). Thus, the signal encoded at output of the ΣΔ modulator has a small number of bits and high resolution in the band. This is typically the case in CD readers where the output of the modulator is obtained on 1 bit whereas the input signal is encoded on about 20 bits.
However, if the signal is an analog signal, with the analog-digital converter 2 (a source of quantization that limits the resolution) being placed at output of the loop as can be seen in FIG. 1(b), the result is that the filtering 11, which integrates the input/output error, is necessarily an analog filtering. Two cases arise. The first is that frequency of the signal is low enough. In this case the signal may be sampled at the entry to the loop (not shown) before the filtering 11, which is then done in the discrete time domain (using switched capacitors for example). The second possible case arises at higher frequencies, especially on carriers: in this case the discrete time techniques (switched-capacitor or switched-current loop techniques, especially) are inappropriate. The filtering 11 can then be continuous-time filtering. The most commonly used technology here is the GmC technology (entailing the use of transconductance amplifiers). The sampling is then done at output of the loop, just before the quantization (analog-digital conversion).
Furthermore, referring again to the high frequencies, the cumulated conversion times of the analog-digital converter (ADC) 2 and of the digital-analog analog converter de (DAC) 3 are spread over several sampling periods instead of being smaller than a single period. This problem disappears if the encoding is done on only one bit, but then the very high non-linearity of the encoding function means that it is not possible to define a criterion of stability for the ΣΔ modulator with certainty. A multi-bit encoding is then preferred. For this encoding, the response of the open loop may be considered to be a first-order linear response.
The making of the loop filter 11 must then resolve the classic problem of feedback control loops: providing the maximum gain (and thus minimizing the error between the feedback-controlled signal and the control) while preserving the stability of the loop. This is especially difficult to achieve since the total delay time of the loop, also known as the latency number, is great. It is the difficulty of finding filtering functions that perform well, even in the presence of high latency numbers, that has hitherto hampered the development of continuous-time ΣΔ modulators.

Continuous-time integrating filter with minimum phase variation, and bandpass ΣΔ modulator using such a filter


A rotor for a dynamo-electric machine is capable of reducing the leakage of magnetic flux between triangular magnetic poles, making it possible to protect magnets disposed between the triangular magnetic poles from damage. The rotor is equipped with: a rotor coil through which current flows to generate magnetic flux; a field core which is provided such that it covers the rotor coil and which is composed of a first field core member and a second field core member having a triangular magnetic poles, respectively; a plurality of magnets which are disposed between adjacent triangular magnetic poles and which have been magnetized in a direction so as to reduce the leakage of the magnetic flux between the triangular magnetic poles. Each magnet is constituted by a first magnet section secured by a securing means to the triangular magnetic pole of the first field core member and a second magnet section secured by a securing means to the triangular magnetic pole of the second field core member.

1. Field of the Invention
The present invention relates to a rotor for a dynamo-electric machine, the rotor being equipped with magnets provided between adjacent triangular magnetic poles to reduce the leakage of magnetic flux between the triangular magnetic poles.
2. Description of Related Art
FIG. 12 is a sectional side elevation of a conventional vehicular AC generator; and FIG. 13 is a perspective view of a rotor shown in FIG. 12. The AC generator is equipped with: a case 3 comprised of a front bracket 1 and a rear bracket 2 made of aluminum; a shaft 6 which is provided in the case 3 and which has a pulley 4 fixed at one end thereof; a Randell-type rotor 7 secured to the shaft 6; fans 5 secured to both side surfaces of the rotor 7; a stator 8 secured to the inner wall surface of the case 3; a slip ring 9 which is secured to the other end of the shaft 6 and which supplies current to the rotor 7; a pair of brushes 10 in sliding contact with the slip ring 9; a brush holder 11 which holds the brushes 10; a rectifier 12 which is electrically connected to the stator 8 to rectify alternating current generated in the stator 8 to direct current; a heat sink 17 fitted onto the brush holder 11; and a regulator 18 which is bonded to the heat sink 17 to adjust the magnitude of the AC voltage generated in the stator 8.
The rotor 7 is constituted by a rotor coil 13 through which current flows to generate magnetic flux, and a field core assembly 14 which is provided such that it covers the rotor coil 13 and in which magnetic poles are formed by the magnetic flux. The field core assembly 14 is composed of a pair of first field core member 21 and second field core member 22 which are alternately meshed. The first field core member 21 and the second field core member 22 are made of iron; the first field core member 21 has triangular magnetic poles 23, and the second field core member 22 has triangular magnetic poles 24. A hexahedral magnet 19 which has been magnetized in a direction so as to reduce the leakage of the magnetic flux between triangular magnetic poles 23 and 24 is secured at each pair of adjacent triangular magnetic poles 23 and 24.
The stator 8 is provided with a stator core 15, and a stator coil 16 which is composed of a conductor wound around the stator core 15 and in which alternating current is generated as the magnetic flux from the rotor coil 13 changes as the rotor 7 rotates.
In the vehicular AC generator configured as set forth above, current is supplied from a battery, not shown, to the rotor coil 13 via the brushes 10 and the slip ring 9 so as to generate magnetic flux; the triangular magnetic poles 23 of the first field core member 21 are magnetized to the N pole, while the triangular magnetic poles 24 of the second field core 22 are magnetized to the S pole. The pulley 4 is driven by an engine and the rotor 7 is rotated through the shaft 6, so that a rotary magnetic field is supplied to the stator coil 16, thus generating an electromotive force in the stator coil 16. This AC electromotive force is rectified into direct current through the rectifier 12 and the magnitude thereof is adjusted by the regulator 18 before it is supplied to the battery.
In the conventional vehicular AC generator, when the AC voltage is generated in the stator coil 16 as the rotor 7 rotates, a constant magnetic repulsion is generated between the outer peripheral surface of the rotor 7 and the inner peripheral surface of the stator 8; hence, vibration is apt to take place in the directions indicated by arrows A to the triangular magnetic poles 23 and 24 as shown in FIG. 14. Thus, there has been a problem in that a load applied to the triangular magnetic poles 23 and 24 causes the magnets 19, which have been secured to the triangular magnetic poles, to also be subjected to a load. This causes the magnet 19 to be distorted, and perhaps damaged.


A micro stacked type chip antenna, wherein a plurality of elementary layers printed with radiation metallic electrodes are stacked up to allow the radiation metallic electrodes on the elementary layers to electrically connect each with its neighboring ones (one) of the radiation metallic electrodes on its upper one and/or lower one of the elementary layers; and then these elementary layers stacked up are packed in a packing process, a plurality of connecting pins are connected respectively with the radiation metallic electrodes on different elementary layers, the tailing end of each connecting pin is extended out of a packing envelop; by various options of connecting of the connecting pins, resonant frequencies of different band widths can be obtained.

1. Field of the Invention
The present invention relates to a micro stacked type chip antenna, and especially to a micro stacked type chip antenna having multiple elementary layers being stacked and packed, the micro stacked type chip antenna can provide various options for getting a suitable band width as required.
2. Description of the Prior Art
Wireless communication has been being well developed nowadays, the range of using of radio frequencies becomes more and more extended; for instance, communication frequencies for satellite communication, wireless network, digital televisions, mobile phones etc. are different from one another. The conventional way is to design an antenna of a resonant frequency for a kind of frequency demand; thereby, there have been being a variant development, and various patent designs.
An advanced micro stacked type chip antenna used presently has a radiation metallic electrode packed in dielectric material, such as ceramic material, in order that the antenna can be integrated with a semiconductor die or chip having an electronic system to achieve an object of miniaturization.
Since developing of chip antennas, now there are chip antennas with the function of operating on two frequencies; however after all, such chip antennas are limited to the range of use of very small band widths; they are unable to meet the requirements of all kinds of frequencies.
Some kind of monopole antenna is provided with a plurality of component sheets stacked from bottom to top, wherein a gap for adjusting impedance matching is provided between every two component sheets, and the component sheets form centrally thereof an integral connecting neck, a feed-in line is provided on the bottom of the antenna; the component sheets get their desired broad bandwidth by adjusting the height stacked by the component sheets. The antenna obtained from such an idea is suitable for many kinds of frequencies covering the CMDA (code vision multiple access) system (824-894 MHZ), the Pan Europe mobile phone system (GSM, 880-960 MHZ), the digital communication system (DSC, 1710-1880 MHZ), the personal communication system ( PCS, 1850-1990 MHZ), the personal mobile phone system (PHS, 1905-1920 MHZ) and the broadband code vision multiple access system (WCDMA, 2010-2025 MHZ).
By virtue that such an antenna can have the desired broad bandwidth for use adjusted according to the stacked height of the component sheets, the main motive of the present invention thus is resided in a question whether a micro antenna can be provided to be more suitable for various ranges of frequency.


This apparatus relates to a safety mechanism for a rail system having tracks adapted to be moved in an out of alignment for the transfer of an object from one track to the other. More specifically, the apparatus relates to a mechanism which prevents the accidental movement of an object off the end of one track unless the tracks are in substantial alignment.

In rail systems of the present invention, bins suspended from one track are electrically driven onto another track, and vice versa as needed. A bridge crane transfers bins from tracks at charging stations to tracks at unloading stations and returned, empty, alternately to charging stations. The tracks at the charging and unloading stations are known as "spur tracks." When the track carried by the bridge crane and the spur tracks are not aligned, the bin could be inadvertently driven off the end of the track onto the floor. Regulations require that a stop be engaged to block the bin from passing the end of an open track.


There is provided an image formation device comprising an developer holding body having a holding surface parallel with a main scanning direction and holding thereon developer; an developer supplying unit to carry developer along a carrying path, wherein the developer supplying unit comprises first carrying electrodes arranged along the carrying path and serving to carry the developer in a carrying direction; second carrying electrodes arranged along the carrying path to face the first electrodes and serving to carry the developer in the carrying direction; a first voltage applying unit to apply a first carrying voltage having a first frequency to the first carrying electrodes; and a second voltage applying unit to apply, to the second carrying electrodes, a second carrying voltage having a second frequency different from the first frequency.

1. Technical Field
Aspects of the present invention relate to an image formation device and a developer supplying device.
2. Related Art
Developer supplying devices configured to supply developer (e.g., dry type developer (dry type toner)) to a supply target for developer (e.g., a photosensitive drum) have been widely used. Image formation devices employing such a developer supplying device have also been widely used.
Examples of such image formation devices or developer supplying devices are disclosed in Japanese Patent Provisional Publication No. SHO 63-13069A, Japanese Patent Examined Publication HEI 5-31146, Japanese Patent Provisional Publication No. HEI 5-19616A, and Japanese Patent Provisional Publication No. 2008-40045A (hereafter, referred to as JP2008-40045A).
Among the image formation devices or the developer supplying devices disclosed in the above described publications, the developer carrying device disclosed in JP2008-40045A is configured to employ two developer carrying units located to face with respect to each other. More specifically, the device disclosed in JP2008-40045A is provided with a carrying printed circuit board on which a plurality of carrying electrodes are formed and an opposite printed circuit board on which a plurality of opposite electrodes are formed. Between the carrying printed circuit board and the opposite printed circuit board, a predetermined gap is formed. To the plurality of carrying electrodes of the carrying printed circuit board and the plurality of opposite electrodes of the opposite printed circuit board, voltages for carrying the developer in a predetermined developer carrying direction are respectively applied.

Image formation device and developer supplying device


A data retrieval system having a database storing data as a vector that has been digitized based on a keyword. The system has capability of generating a residual vector from the data to compute a covariance matrix and an eigenvector of the covariance matrix. The system further has the capability for generating and storing a set of basic vectors from the set of the computed eigenvectors, and for reading out the data and at least one of the eigenvectors from a memory. This is utilized to compute a contribution of the eigenvector to the data, and for contracting or enlarging a residual vector to store. The system selects a keyword to be used for labeling according to a similarity between the stored basic vector and the data, and a weight on the similarity so as to store the keyword in a memory.

Recently, with the progress of computer hardware, the amount of information to be processed has more and more increased, and the database for storing the information has become larger. This trend is more remarkable in recent years when, in addition to the progress of the computer hardware, the network technology allows necessary information to be acquired using a browser software via the Internet.
Up to now, there have been proposed various methods for detecting document in a large scale database that may be arranged to include the document data, image data and audio data. For example, in Published Unexamined Patent Application No. 2002-024268 by Kobayashi and others, there was disclosed a method and system for efficiently detecting a group of a relatively small number of documents having the same or similar keyword (hereinafter referred to as an outlier cluster) among the documents included in the database. Likewise, in "Latent semantic space: iterative scaling improves precision of inter-document similarity measurement", SIGIR 2000, pp. 216–223 and SIGR 2001, pp. 152–154 by Kubota and others, a method has been proposed for efficiently retrieving an outlier cluster by scaling a document vector in a potential semantic space. Though various methods and systems for retrieving a group of a small number of documents in the database as the outlier cluster have been proposed as above described, they may be applied to a relatively small database configured by sampling, but not fully applied to a larger database storing millions of documents in terms of the retrieval speed and the detectability of outlier cluster. Though the retrieval speed is possibly improved to some extent if the computer performance is enhanced, the retrieval for the outlier cluster must be separately improved by utilizing the characteristics of document keyword matrix in the linear algebra.
Usually, the document data in the large scale database is digitized depending on whether or not a registered keyword is contained, configured as a document keyword vector, and stored in the database. The above method for retrieving the outlier cluster in the large scale database relies on calculating a residual matrix generated by successively deleting the document vector having the greatest norm. This successive calculation for the residual matrix is required to store in a main memory of the computer the matrix successively generated using an engenvector or singular vector. For example, the document data having a size of the number of documents' the number of attributes (keywords) is required to store in the main memory. Herein, in a case where the number of documents is 100,000, and the number of keywords is 1000, it is necessary to have a storage capacity of 100,000′1000′8 bytes=800 MB to store the residual matrix in real number at double precision. If the number of documents and the number of keyword are increased, an amount of data that can not be stored by the ordinary computer must be stored by generating the residual matrix. In this invention, the document keyword vector digitized based on the keyword is simply referred to as the data.
On the other hand, various cluster retrieval techniques for application to the information retrieval or data mining have been so far offered. For example, Edie Rasmussen, "Clustering Algorisms", Chapter 16, Information Retrieval, W. B. Frankes and R. Baeza-Yates Eds, Prentice Hall (1992), L. Kaufman and P. J. Rousseuw, "Finding Groups in Data", John Wiley & Sons (1990) disclosed the techniques. Also, a method for automatically labeling the detected cluster was disclosed in Alexandrian Popescul and Lyle H. Unger, "Automatic Labeling of Document Clusters", (2000). The simplest method involves labeling the cluster of given document with a word having the greatest appearance frequency.
Though the above method is simple, the cluster labeling is not sufficient, resulting in loss of the meaning of labeling, when meaningless words frequently appear in the document. In addition, there are a method for labeling the cluster with a word mostly predicted in the cluster, instead of the frequency, and a method for labeling the cluster with a title of document nearest the center of multi-dimensional data that is a constituent of the cluster. However, labeling that reflects the characteristics of cluster is not always possible. Furthermore, there is a method for labeling the cluster with the frequency information and the most predicted word by introducing a tree structure in the documents, but it is troublesome to introduce the tree structure. The above methods have a drawback of being short of full identification when the keyword used in labeling is contained in the data constituting other cluster.
In the above retrieval for outlier cluster, to enhance the availability of retrieved result, it is necessary that the outlier cluster is clearly distinguished from the major cluster, and the attribute (keyword) forming the outlier cluster is effectively presented to the user.
As above described, there is a need for the data retrieval method and system to solve the problem of scalability associated with calculation of the residual matrix and improve the retrieval for the outlier cluster. Also, there is a need for the data retrieval method and system to label the major cluster and the outlier cluster in calculating each cluster and to improve the identification of each cluster. A still further need is for a graphical user interface system capable of making more effective use of the retrieved results by efficiently presenting the attribute (keyword) of the retrieved cluster to the user who has retrieved them.

Data retrieval method, system and program product

International Business Machines Corporation


A method of preheating a brushless motor that includes sequentially energizing and de-energizing a phase winding over one or more drive periods. The phase winding is energized in the same direction throughout each drive period so as to lock a rotor of the motor at an aligned position.

It may be necessary to start a brushless motor at temperatures well below that of the normal running temperature. At relatively low temperatures, the viscosity of the grease within the bearings of the motor may hamper or prevent the motor from starting. Additionally, at sub-zero temperatures, icing may occur between the rotor and stator, which further hampers or prevents starting of the motor. Even if it is possible to start the motor, driving the motor under such conditions may damage components of the motor.
Schemes for preheating a motor are known but generally suffer from one or more disadvantages. For example, the motor may include a heating device that heats the motor to a predetermined temperature prior to starting. However, the provision of a heating device increases the cost of the motor.