When Raman amplification is performed, the occurrence of lightwaves through FWM in a wavelength band of input signal light is suppressed, thereby avoiding deterioration of the signal quality. Allocation of lightwaves of the pumping light is controlled so that, wavelengths of lightwaves arising through a nonlinear effect of pumping lights generated by a pumping means or of pumping lights and input signal light, or both, are not within the wavelength band of the input signal light.

1. Field of the Invention
The present invention is used for optical communication and concerns especially, an optical amplifier used for Raman amplification.
2. Description of Related Art
In a wavelength division multiplex (WDM) optical transmission system, signal channels having a plurality of different wavelengths are simultaneously transmitted in one optical fiber. This means that in a WDM transmission system, increasing the number of wavelengths (the number of signal channels) expands the transmission capacity for each optical fiber thereby enabling greater economy in the number of optical fibers.
A WDM optical transmission system is comprised mainly of: (1) an optical transmitter installed in a transmitting terminal, (2) an optical receiver installed in a receiving terminal and (3) an optical transmission line connecting the optical transmitter and receiver. Usually, an optical transmission line is comprised of: (A) a plurality of optical amplifiers such as erbium doped optical fiber amplifiers, for amplifying WDM optical signals and (B) a plurality of transmission optical fibers connecting between the optical amplifiers.
The signal quality of signal light output from an optical transmitter deteriorates as it is transmitted through an optical transmission line. The primary factors of this deterioration are degradation through amplified spontaneous emission (ASE) and degradation due to nonlinear effects. ASE refers to a constant amount of light with random phases. Nonlinear effects include various kinds of effects, among which distortion due to self phase modulation group velocity dispersion (SPM-GVD) is the most typical one. Distortion due to SPM-GVD refers to a wave distortion caused by time-dependent nonlinear refractive index changes in the transmission fiber induced by signal light pulses. The distortion increases with the signal light power.
Signal deterioration caused by ASE has a tendency to increase as signal light power output from transmission fiber decreases. This is because the output terminal of a transmission fiber is normally connected to the input terminal of an optical amplifier which usually generates a constant amount of optical noise. Therefore, if signal power output from transmission fiber decreases, the ratio of signal power to ASE, that is to say, the signal-to-noise ratio (SNR) decreases leading to signal degradation. In other words, to reduce the effects of ASE, higher signal light power is preferable at the output of a transmission fiber.
Signal deterioration from nonlinear wave distortion caused by SPM-GVD has a tendency to increase as signal light power input into transmission fiber increases. This is because the nonlinear refractive index change that causes SPM-GVD nonlinear waveform distortion increases together with signal light power. Accordingly, to reduce the effects of nonlinear wave distortion caused by SPM-GVD, lower signal light power is preferable at the input of a transmission fiber.
Accordingly, due to these two kinds of signal deterioration, higher signal light power is preferable at the output of a transmission fiber while lower signal light power is preferable at the input of a transmission fiber. However, because the output signal light power and the input signal light power is related uniquely though the optical transmission fiber loss, both those conditions cannot be satisfied simultaneously. Therefore, signal light power is usually set to minimize the overall deterioration from the both kinds.
Even with signal light power at optimum conditions, both these deterioration cannot be completely avoided. Further, both these kinds of deterioration accumulate and worsen as signals pass through a plurality of optical amplifiers and transmission fibers. Therefore, the maximum transmission distance for an optical transmission system is usually restricted by the accumulation of deterioration through both causes.
For relaxing such restrictions, methods and systems using Raman amplification are proposed. Raman amplification refers to a phenomenon wherein amplification of signal light inside transmission fiber is achieved via the stimulated Raman effect. This occurs as pumping light, light of specific wavelengths different from the wavelengths of the signal lights, is input into the transmission fiber simultaneously with the signal light. There are three configurations for a system using Raman amplification: the xe2x80x9cbackward pumpingxe2x80x9d configuration where backward pumping light is transmitted in the opposite direction to the signal light; the xe2x80x9cforward pumpingxe2x80x9d configuration where forward pumping light is transmitted in the same direction as the signal light; and the xe2x80x9cbidirectional pumpingxe2x80x9d configuration where both forward pumping light and backward pumping light are transmitted in the same direction and the opposite direction to the signal light, respectively. By using Raman amplification of any of these three configurations, it is possible to achieve better signal quality than provided by a configuration not applying Raman amplification, if signal light power of at the input of the transmission fiber is appropriately set.
Improved signal quality through forward pumping will now be described with reference to FIG. 13. In FIG. 13 distance along the transmission fiber is plotted on the horizontal axis and average signal light power is plotted on the vertical axis. Average signal light power in transmission fiber for a system not applying Raman amplification is shown by (a) of FIG. 13. Here, if forward pumping light is injected from the input terminal of the transmission fiber, the signal light is amplified within the transmission fiber and signal power inside the transmission fiber changes as shown by (b) of FIG. 13. If, here, input signal power is lowered so that average signal light output from the transmission fiber is the same as before Raman amplification is applied, the result would be as shown by (c) of FIG. 13. This means that as it is possible to decrease input signal light power while maintaining the output signal light power from the transmission fiber constant (keeping deterioration caused by ASE constant). This means that nonlinear waveform distortion degradation from SPM-GVD can be reduced, leading to improved signal quality.
Four wave mixing (FWM) is another typical kind of nonlinear effect. FWM refers to the effect of power conversion between four lightwaves via the third order optical nonlinear effect of a transmission fiber.
This effect occurs whether the wavelengths of the four lightwaves are all the same, are all different or whether some are the same and some are not. Usually, the field of optical communication is concerned with the case where all four of the lightwaves are of different wavelengths or where two of the four lightwaves have the same wavelengths while the other 2 have different wavelengths. In the former case, if the wavelengths of the four lightwaves in ascending order of wavelength are xcex1, xcex2, xcex3, xcex4, power conversion between these four lightwaves through FWM arises when for example the following conditions are met:
xcex4=xcex1xc3x97xcex2xc3x97xcex3/(xcex1xc3x97xcex2xe2x88x92xcex2xc3x97xcex3+xcex3xc3x97xcex1)
If xcex1=1530 nm, xcex2=1535 nm, xcex3=1580 nm for example, power conversion between the four lightwaves occurs when xcex4=1585 nm. This results in the power elements of wavelengths xcex1, xcex2, xcex3 to be mixed into the lightwave of wavelength xcex4. (If there was no wave of wavelength xcex4 originally, a new lightwave would arise). Because these four lightwaves represent different wavelength channels, mixture of signal light leads to deterioration of signal quality (For example, for wavelength channel of xcex4, power elements xcex1, xcex2, xcex3 are noise). Thus, FWM should be avoided. A means for avoiding signal quality degradation caused by FWM is to allocate signal light wavelengths avoiding the conditions of the above expression. Lowering input signal light power into the transmission fiber is also effective because the FWM increase together with the power of the four lightwaves. Information on this method can be found in H. Suzuki et al, Optical Fiber Communication Conference and the International Conference on Integrated Optics and Optical Fiber Communication ""99 Technical Digest, ThO4 or JP 2000-330145 A for example. Further, because power conversion efficiency in FWM decreases as the absolute value of the chromatic dispersion on transmission fiber increases, the effect of FWM can be suppressed by using transmission fiber with absolute value of chromatic dispersion equal to 2 ps/nm/km or greater at the wavelength bands of signal light. For wavelength band in the 1550 nm region for example, fiber with chromatic dispersion of 2 to 10 ps/nm/km, called nonzero dispersion shifted fiber, can be utilized.
If however Raman amplification is applied for fiber having chromatic dispersion of 2 to 10 ps/nm/km at the wavelength band of the signal light, problems arise. Even though the absolute value of chromatic dispersion may be sufficiently large at the wavelength band of the signal light, it may be too small at the wavelength region of the pumping light, leading FWM to occur strongly. Accordingly, due to FWM between pumping lights, and/or FWM between pumping lights and signal lights, there is a possibility of power mixture between pumping lights and signal lights, causing distortion and a deterioration in signal quality. This problem is particularly significant when the forward pumping configuration of Raman amplification is used. At present, there are no papers clarifying the issues and providing solutions concerning FWM effects on pumping light for Raman amplification, thus the problems remain unsolved.
Against the background of these problems the object of the present invention is to provide a Raman amplifier, pumping apparatus and program therefor that enables the problem of deterioration in signal quality to be avoided by suppressing the occurrence of lightwaves from FWM in wavelength bands of signal light by appropriately setting the wavelengths or power, or both, of pumping lights used for Raman amplification.
According to the present invention, in a Raman amplifier wherein signal light is provided with gain in a Raman amplification medium through the stimulated Raman effect and which comprises a pumping means for injecting pumping light into the Raman amplification medium, the wavelengths of the lightwaves are allocated so that wavelengths of lightwaves arising from a nonlinear effect of the pumping lights generated by the pumping means or the pumping light and the signal light, or both, do not fall within the wavelength band of the signal light.
Basically, this invention is characterized in that the pumping means generates pumping lights of a plurality of wavelengths and in respect of two arbitrary pumping lights of those pumping lights of a plurality of wavelengths, the peak wavelength, xcexmin, of pumping light having the shorter wavelength and the peak wavelength, xcexmax, of pumping light having the longer wavelength are in a relationship to the shortest wavelength of the wavelength band of the signal light, xcexshort and the longest wavelength of the wavelength band of the signal light, xcexlong, expressed as
xcexshort greater than xcexminxc3x97xcexmax/(2xcexminxe2x88x92xcexmax)
or
xcexminxc3x97xcexmax/(2xcexminxe2x88x92xcexmax) greater than xcexlong.
Three arbitrary pumping lights from among the a plurality of pumping lights, the peak wavelengths of which three pumping lights satisfy the expression
xcexmin less than xcexmid less than xcexmax
are in a relationship to the shortest wavelength of the wavelength band of the signal light, xcexshort and the longest wavelength of the wavelength band of the signal light, xcexlong, expressed as
xcexshort greater than xcexmaxxc3x97xcexmidxc3x97xcexmin/(xcexmidxc3x97xcexminxe2x88x92xcexmaxxc3x97xcexmid+xcexmaxxc3x97xcexmin)
or
xcexmaxxc3x97xcexmidxc3x97xcexmin/(xcexmidxc3x97xcexminxe2x88x92xcexmaxxc3x97xcexmid+xcexmaxxc3x97xcexmin) greater than xcexlong.
With the present invention, the wavelengths or the power, or both, of the pumping lights are allocated or set so that, lightwave power arising through a nonlinear effect of pumping lights generated by the pumping means, or the pumping light and the input light signal, or both, is, within the wavelength band of the signal light, at all points of the Raman amplification medium, 20 dB or more smaller than or one part per hundred or less of, the power of the signal light.
Thus, with the present invention, by setting the wavelength or power, or both, of pumping lights, deterioration of signal light quality due to lightwaves arising through FWM can be avoided or suppressed.
This invention is especially effective where the absolute value of chromatic dispersion in the transmission fiber is equal to or greater than 2 ps/nm/km and equal to or less than 10 ps/nm/km anywhere within the wavelength band of the signal light.
The present invention is also effective in a system wherein zero-dispersion wavelength of the transmission fiber is equal to or greater than the peak wavelength of the pumping light having the shortest peak wavelength from among the pumping lights and equal to or less than the peak wavelength of the pumping light having the longest peak wavelength from among the pumping lights. Further, this invention is especially effective when the forward pumping configuration is used.
That is to say, according to a first aspect of this invention, it is provided a Raman amplifier comprising a Raman amplification medium that provides signal light with gain though the stimulated Raman effect and a pumping means for injecting pumping lights of a plurality of wavelengths in this Raman amplification medium.
This invention is characterized by comprising a means for allocating wavelengths of the pumping lights, so that in respect of two arbitrary pumping lights among the pumping lights of a plurality of wavelengths generated by the pumping means, the peak wavelength xcexmin, of pumping light having the shorter wavelength and the peak wavelength xcexmax, of pumping light having the longer wavelength are in a relationship to the shortest wavelength of the wavelength band of the signal light, xcexshort and the longest wavelength of the wavelength band of the signal light, xcexlong, expressed as
xcexshort greater than xcexminxc3x97xcexmax/(2xcexminxe2x88x92xcexmax)
or
xcexminxc3x97xcexmax/(2xcexminxe2x88x92xcexmax) greater than xcexlong.
Alternatively, this invention is characterized by comprising a means for allocating wavelengths of the pumping lights so that three arbitrary pumping lights from among the pumping lights of a plurality of wavelengths generated by the pumping means, the peak wavelengths of which three pumping lights satisfy the expression
xcexmin less than xcexmid less than xcexmax
are in a relationship to the shortest wavelength of the wavelength band of the signal light, xcexshort and the longest wavelength of the wavelength band of the signal light, xcexlong, expressed as
xcexshort greater than xcexmaxxc3x97xcexmidxc3x97xcexmin/(xcexmidxc3x97xcexminxe2x88x92xcexmaxxc3x97xcexmid+xcexmaxxc3x97xcexmin)
or
xcexmaxxc3x97xcexmidxc3x97xcexmin/(xcexmidxc3x97xcexminxe2x88x92xcexmaxxc3x97xcexmid+xcexmaxxc3x97xcexmin) greater than xcexlong.
Alternatively, this invention is characterized by comprising a means for setting or allocating the wavelengths or the power, or both, of the pumping lights, so that the power of lightwaves arising through a nonlinear effect of the pumping lights generated by the pumping means, or of the pumping lights and the input signal, or both, is, within the wavelength band of the signal light, at all point of the Raman amplification medium, 20 dB or more smaller than or one part per hundred or less of, the power of the signal light. This nonlinear effect could be for example, FWM.
It is preferable for the Raman amplification medium to include optical fiber, the absolute value of the chromatic dispersion of which fiber is, equal to or greater than 2 ps/nm/km and equal to or less than 10 ps/nm/km anywhere within the wavelength band of the signal light.
It is also preferable for the Raman amplification medium to include optical fiber, the zero-dispersion wavelength of which optical fiber is equal to or greater than the peak wavelength of the pumping light having the shortest peak wavelength from among the pumping lights and equal to or less than the peak wavelength of the pumping light having the longest peak wavelength from among the pumping lights.
It is preferable for the present invention to provide a forward pumping means for transmitting at least a portion of pumping light generated by the pumping means, inside the Raman amplification medium in the same direction as the signal light.
According to a second aspect of this invention, it is provided a pumping apparatus comprising a pumping means for injecting pumping lights of a plurality of wavelengths into the Raman amplification medium that provides signal light with gain though the stimulated Raman effect.
The second aspect of this invention is characterized by comprising a means for allocating wavelengths of the pumping lights so that, in respect of two arbitrary pumping lights among the pumping lights of a plurality of wavelengths generated by the pumping means, the peak wavelength xcexmin, of pumping light having the shorter wavelength and the peak wavelength xcexmax, of pumping light having the longer wavelength are in a relationship to the shortest wavelength of the wavelength band of the signal light, xcexshort and the longest wavelength of the wavelength band of the signal light, xcexlong, expressed as
xcexshort greater than xcexminxc3x97xcexmax/(2xcexminxe2x88x92xcexmax)
or
xcexminxc3x97xcexmax/(2xcexminxe2x88x92xcexmax) greater than xcexlong.
Alternatively, the second aspect of this invention is characterized by comprising a means for allocating wavelengths of the pumping lights so that three arbitrary pumping lights from among the pumping lights of a plurality of wavelengths generated by the pumping means the peak wavelengths of which three pumping lights satisfy the expression
xcexmin less than xcexmid less than xcexmax
are in a relationship to the shortest wavelength of the wavelength band of the signal light, xcexshort and the longest wavelength of the wavelength band of the signal light, xcexlong, expressed as
xcexshort greater than xcexmaxxc3x97xcexmidxc3x97xcexmin/(xcexmidxc3x97xcexminxe2x88x92xcexmaxxc3x97xcexmid+xcexmaxxc3x97xcexmin)
or
xe2x80x83xcexmaxxc3x97xcexmidxc3x97xcexmin/(xcexmidxc3x97xcexminxe2x88x92xcexmaxxc3x97xcexmid+xcexmaxxc3x97xcexmin) greater than xcexlong.
Alternatively, the second aspect of this invention is characterized by comprising a means for setting or allocating the wavelengths or the power, or both, of the pumping lights, so that the power of light arising from a nonlinear effect of the pumping lights generated by the pumping means, or of the pumping lights and the input signal, or both, is, within the wavelength band of the signal light, at all points of the Raman amplification medium, 20 dB or more smaller than or one part per hundred or less of, the power of the signal light. This nonlinear effect could be for example, FWM.
It is preferable for the second aspect of this invention to comprise a forward pumping means for transmitting at least a portion of pumping light generated by the pumping means in the same direction as the light signal inside the Raman amplification medium.
The third aspect of this invention is a program, characterized in that, installation of this program in an information processing system, provides for that information processing system, as functionality for allocating wavelengths of pumping lights applicable for a Raman amplifier comprising a Raman amplification medium that provides signal light with gain though the stimulated Raman effect and a pumping means for injecting pumping lights of a plurality of wavelengths into this Raman amplification medium, or for a pumping apparatus comprising a pumping means for injecting pumping lights of a plurality of wavelengths into a Raman amplification medium that provides signal light with gain though the stimulated Raman effect, functionality that realizes allocation of wavelengths of the pumping lights so that, in respect of two arbitrary pumping lights among the pumping lights of a plurality of wavelengths generated by the pumping means, the peak wavelength xcexmin, of pumping light having the shorter wavelength and the peak wavelength xcexmax, of pumping light having the longer wavelength are in a relationship to the shortest wavelength of the wavelength band of the signal light, xcexshort and the longest wavelength of the wavelength band of the signal light, xcexlong, expressed as
xcexshort greater than xcexminxc3x97xcexmax/(2xcexminxe2x88x92xcexmax)
or
xcexminxc3x97xcexmax/(2xcexminxe2x88x92xcexmax) greater than xcexlong.
Alternatively, the third aspect of this invention realizes functionality for allocating wavelengths of the pumping lights wherein three arbitrary pumping lights from among the pumping lights of a plurality of wavelengths generated by the pumping means, the peak wavelengths of which three pumping lights satisfy the expression
xcexmin less than xcexmid less than xcexmax
are in a relationship to the shortest wavelength of the wavelength band of the signal light, xcexshort and the longest wavelength of the wavelength band of the signal light, xcexlong, expressed as
xcexshort greater than xcexmaxxc3x97xcexmidxc3x97xcexmin/(xcexmidxc3x97xcexminxe2x88x92xcexmaxxc3x97xcexmid+xcexmaxxc3x97xcexmin)
or
xcexmaxxc3x97xcexmidxc3x97xcexmin/(xcexmidxc3x97xcexminxe2x88x92xcexmaxxc3x97xcexmid+xcexmaxxc3x97xcexmin) greater than xcexlong.
Moreover, installing the program according to the third aspect of this invention in an information processing system, comprises that information processing system, as functionality for allocating or setting the wavelengths or power, or both, of pumping lights applicable for a Raman amplifier comprising a Raman amplification medium that provides signal light with gain though the stimulated Raman effect and a pumping means for injecting pumping lights of a plurality of wavelengths into this Raman amplification medium, or for a pumping apparatus providing a pumping means for injecting pumping lights of a plurality of wavelengths in a Raman amplification medium that provides signal light with gain though the stimulated Raman effect, functionality that realizes allocation or setting of the wavelengths or power, or both, of the pumping lights, so that the power of light arising through a nonlinear effect of pumping lights generated by the pumping means, or of pumping lights and the signal light, or both, is, within the wavelength band of the signal light, at all points of the Raman amplification medium, 20 dB or more smaller than or one part per hundred or less of, the power of the signal light. This nonlinear effect could be for example, FWM.
By recording the program of this invention onto a recording medium, the recording medium can be used to install the program of this invention in the information processing system. Alternatively, the program of this invention can be installed directly in the information processing system from a server storing the program connected to the system via a network.
Accordingly, a Raman amplifier and pumping apparatus can be realized that enable the problem of deterioration in signal quality to be avoided by means of suppressing the occurrence of lightwaves from FWM in the wavelength band of signal light by setting the wavelengths or power or both the wavelengths and power of pumping light used for Raman amplification appropriately using an information processing system like a computer.

Raman amplifier and pumping apparatus, and program


A (meth)acryloyl compound represented by the following formula (A):

For photoresist components, resin raw materials intended for materials for electric or electronic components or structural materials, or resin curing agents, (meth)acryloyl compounds having a bisphenol skeleton are known to be useful from the viewpoint of various properties (such as optical properties, heat resistance, water resistance, moisture resistance, chemical resistance, electrical properties, mechanical properties, and dimensional stability) (see Patent Literatures 1 to 5).
Various materials have also been proposed for optical component forming compositions. For example, acrylic resins (see Patent Literatures 6 to 8) and polyphenol having a specific structure derived from an allyl group (see Patent Literature 14) have been proposed.

(Meth)acryloyl compound and method for producing same

Abstract: wherein X is a 2m-valent group having 1 to 60 carbon atoms or a single bond; each Z is independently an oxygen atom, a sulfur atom, or not a crosslink; each R1 is independently a linear, branched, or cyclic alkyl group having 1 to 30 carbon atoms, an aryl group having 6 to 30 carbon atoms and optionally having a substituent, an alkenyl group having 2 to 30 carbon atoms and optionally having a substituent, an alkoxy group having 1 to 30 carbon atoms and optionally having a substituent, a halogen atom, a nitro group, an amino group, a carboxylic acid group, a thiol group, a hydroxy group, or a group in which a hydrogen atom of a hydroxy group is replaced with a vinylphenylmethyl group, wherein the alkyl group, the aryl group, the alkenyl group, or the alkoxy group optionally contains an ether bond, a ketone bond, or an ester bond; each R1A is independently a methyl group or a hydrogen atom; each k is independently an integer of 0 to 2, provided that all of the k moieties are not 0 at the same time; m is an integer of 1 to 3; each n is independently an integer of 0 to 5; and each p is independently 0 or 1.


A dielectric ceramic composition for microwave use having a relative permittivity xcex5r of 35 to 45, Qf0 value of more than 50,000 GHz (at 7 GHz), and dielectric characteristic of xcfx84f=0xc2x110 ppm/xc2x0 C includes an La2O3.Al2O3.SrO.TiO2 based ceramic composition and a specific quantity of Ga2O3 to increase the Qf0 value and a specific amount of Pr2O3to control the xcfx84f value.

The present invention relates to a dielectric ceramic composition for microwave use having a relative permittivity xcex5r of 35 to 45, Qf0 value of at least 50,000 GHz (at 7 GHz) and a dielectric characteristic of xcfx84f=0xc2x110 ppm/xc2x0 C. employed for microwave communication filters, milliwave communication filters, oscillators, inductor antennas, and frequency adjusting rods etc.
Dielectric ceramic compositions are widely employed in the high-frequency region such as microwaves and milliwaves in for example dielectric resonators, dielectric substrates for MIC and waveguides. The characteristics that these are required to have are: (1) a large relative permittivity xcex5r to meet demands for miniaturization, since the wavelength is reduced to 1/xcex5r1/2 in a dielectric, (2) low dielectric loss at high frequency i.e. high Q value, and (3) small and stable temperature coefficient xcfx84f of resonance frequency.
Conventional examples of such a dielectric ceramic composition are Laxe2x80x94Tixe2x80x94Alxe2x80x94O based compositions (see Japan, J. Appl. Phys. 36 (1997) 6814), which have xcex5r=36, Qf0 value=45,000 GHz, and xcfx84f=xe2x88x922 ppm/xc2x0 C., but their Qf0 values are low.
Also, in the case of Ba(Zn1/3Nb2/3)O3 based compositions (published in: Electronics/Ceramics September 1993 September page 3), xcex5r=41, Qf0 value=86,000 GHz, and xcfx84f=+31 ppm/xc2x0 C., but a dielectric ceramic composition of small xcfx84f is not obtained.
Recently, La2O3.Al2O3.SrO.TiO2 based composition or La2O3.Al2O3.SrO.TiO2.CaO based composition or composition containing one or two or more of Ce, Nb, Ta, Y, Zr, V, Cr, Mo, W, Co, Ni, Cu, Zn, Sn, Bi, B, or Si in the aforementioned ceramic compositions (see Laid-open Japanese Patent Publication H. 11-130528) has been proposed.
Regarding the dielectric characteristic of these ceramic compositions, they have excellent dielectric characteristics with xcex5r of more than 30, Qf0 value more than 25,000 GHz (at 1 GHz) and xcfx84f less than +30 (ppm/xc2x0 C.), but dielectric ceramic compositions of low xcfx84f are not obtained. Recently, with increasingly severe demands for miniaturization of portable terminal electronic equipment, materials of even better dielectric performance are being demanded.
In view of the foregoing demands, an object of the present invention is to provide a dielectric ceramic composition for microwave use having a relative permittivity xcex5r of 35 to 45, Qf0 value of at least 50,000 GHz (at 7 GHz) and a dielectric characteristic of xcfx84f=0xc2x110 ppm/xc2x0 C.
The present invention studied various compositions with the object of obtaining a material capable of being controlled to a relative permittivity xcex5r of 35 to 45, Qf0 value of at least 50,000 GHz (at 7 GHz) and a dielectric characteristic of xcfx84f=0xc2x110 ppm/xc2x0 C, and, as a result, discovered that, with an La2O3.Al2O3.SrO.TiO2 based ceramic composition, by adding a specific quantity of Ga2O3 to the aforesaid ceramic composition, the Qf0 value could be increased, and, by further adding a specific quantity of Pr2O3, control of the xcfx84f value became possible, so that a ceramic composition capable of being controlled to a relative permittivity xcex5r of 35 to 45, Qf0 value of at least 50,000 GHz (at 7 GHz) and a dielectric characteristic of xcfx84f=0xc2x110 ppm/xc2x0 C could be obtained, and thereby perfected the present invention.
Specifically, the present invention consists in a dielectric ceramic composition for microwave use characterized in that the compositional formula is expressed by aAl2O3.bGa2O3.cTiO2.dSrO.eLa2O3.fPr2O3, where a, b, c, d, e and f representing the mol ratios satisfy the following values (the case where b and f are simultaneously 0 is excluded).
a+b+c+d+e+f=1
0.079xe2x89xa6axe2x89xa60.167
0xe2x89xa6bxe2x89xa60.017
0.333xe2x89xa6cxe2x89xa60.412
0.333xe2x89xa6dxe2x89xa60.412
0.035xe2x89xa6exe2x89xa60.167
0xe2x89xa6fxe2x89xa60.101
The reasons why, in the present invention, if the respective mol ratios of Al2O3, Ga2O3, TiO2, SrO, La2O3 and Pr2O3 are a, b, c, d, e, f, these mol ratios are respectively restricted to 0.079xe2x89xa6axe2x89xa60.167, 0xe2x89xa6bxe2x89xa60.017, 0.333xe2x89xa6cxe2x89xa60.412, 0.333xe2x89xa6dxe2x89xa60.412, 0.035xe2x89xa6exe2x89xa60.167, and 0xe2x89xa6fxe2x89xa60.101 are as follows.
If a is less than 0.079, xcex5r increases but the Qf0 value is less than 50,000 GHz, but if it exceeds 0.167 mol ratio, xcex5r is lowered and drops to 35 or lower, which is undesirable.
If b exceeds 0.017 mol ratio, the Qf0 value is lowered, resulting in the Qf0 value dropping below 50,000 GHz, which is undesirable.
If c is less than 0.333 mol ratio, or is lowered, falling to 35 or lower, which is undesirable; if it exceeds 0.412 mol ratio, xcex5r increases, but the Qf0 value drops below 50,000 GHz, which is undesirable.
If d is less than 0.333 mol ratio, xcex5r is lowered, falling to 35 or lower, which is undesirable; if it exceeds 0.412 mol ratio, xcex5r increases, but the Qf0 value drops below 50,000 GHz, which is undesirable.
If e is less than 0.035 mol ratio, xcex5r is increased, but the Qf0 value drops below 50,000 GHz, which is undesirable; if it exceeds 0.167 mol ratio, xcex5r is lowered, falling to 35 or lower, which is undesirable.
If f exceeds 0.101 mol ratio, If becomes quite large, becoming 10 ppm/xc2x0 C. or more, which is undesirable.

Dielectric ceramic composition for microwave use


The invention relates to telecommunication networks and particularly to mobile networks using Asynchronous Transfer Mode (ATM) transmission systems. The invention also relates to the control of mobility and call control functions in ATM systems. According to the invention, a network element (MSC/BSC) of a telecommunication network, such as a mobile network, which in a conventional telecommunication network architecture ensures the switching of circuit-switched connections, is provided with an ATM switching function. ATM switching functions are controlled with the same call and switching control operations (31) that are conventionally used e.g. for the control of a TDM switching field (32) in a PLMN network element. In a minimum implementation, an ATM switching field (301) provided with a suitable control interface (30) is simply arranged in place of or parallel with the TDM switching field. The switching network element thus becomes an ATM network node of a physical or a logical interface layer. PLMN level signalling, mobility management and call control are implemented using solutions offered by existing mobile networks and current PLMN network elements.

The invention relates to telecommunication networks and particularly to mobile networks using ATM (Asynchronous Transfer Mode) transfer systems. The invention also relates to the control of mobility and call control functions in ATM systems.
Two of the current development trends in telecommunication are mobile communication and broadband networks. The term broadband typically refers to a bit rate higher than 2 Mbit/s. Narrowband usually refers to a bit rate of 64 kbit/s or lower. Bit rates from 64 kbit/s to 2 Mbit/s are sometimes referred to as wideband. Broadband networks are attractive for at least two (compatible) reasons:
1) A single broadband network bearer divided among a plurality of users, few or none of whom need the whole bandwidth alone, can offer advantages concerning flexibility and the building of transfer systems.
2) Information to be transferred on separate transfer channels possibly demand broadband channels. Users need new high-quality services, which in turn require high bit rates. Such services include e.g. video conferences, high-speed data transmission, etc. A common denominator for these services is multimedia, which combines image, voice and data into one service.
Due to its numerous strengths, ATM (Asynchronous Transfer Mode) is chosen as the transmission technique in various standardized B-ISDN (Broadband Integrated Services Digital Network) protocol structures. In this connection the term xe2x80x98transmissionxe2x80x99 refers to the use of ATM switching and multiplexing techniques in a data link layer (i.e. an OSI Layer 2, hereinafter referred to as an ATM layer) relaying end user traffic from a source to a destination within a network. Between the source and the destination are established virtual connections, which requires the network to have switching functions. Signalling and user information are normally conveyed by different virtual connections in an ATM layer. A virtual connection is identified in the ATM layer by a Virtual Path Identifier VPI and a Virtual Channel Identifier VCI.
In ATM information is conveyed segmented in fixed-length cells, the number of the cells in a time unit being proportional to the user""s bandwidth requirements. Each 53-octet cell is divided into a 5-octet header and a 48-octet information field, as shown in FIG. 2.
The main purpose of the header is to identify a connection number for a cell sequence providing a virtual channel for a particular call. A plural number of virtual paths, which are multiplexed in the ATM layer, can be connected to one and the same physical layer (i.e. an OSI Layer 1), each path being identified by an 8-bit VPI at a User-to-Network Interface UNI and a 12-bit VPI at a network-node interface. Each path can comprise a plural number of virtual channels, each of which is identified by a 16-bit VCI. The header can also comprise other fields, such as a Header Error Control HEC, a Generic Flow Control GFC, a Cell Loss Priority CLP and a Payload Type PT.
The User-to-Network interface UNI between an ATM user terminal and an ATM switch (a private UNI) and between private and public ATM networks (a public UNI), together with a UNI signalling (and an ATM cell) related thereto, are defined at least in the following recommendations:
[1] ATM User-to-Network Interface Specification, version 3.1, ATM Forum, 1994;
[2] ATM User-to-Network Interface (UNI) Signalling Specification, version 4.0, ATM Forum, June 1994;
[3] ITU-T Recommendation Q.2931 (1994) Broadband Integrated Services Digital Network (B-ISDN), Digital Signalling System No. 2 (DSS 2), User-to-Network Interface (UNI) Layer 3 Specification for Basic Call/Connection Control. ITU-T.
In mobile networks, radio interfaces have conventionally been narrowband. Mobile network transmission systems have conventionally been implemented with circuit-switched connections using a star or tree network configuration. In order to increase the capacity and flexibility of transmission systems, different broadband packet switched transmission systems have also been proposed for mobile networks, e.g. in WO 9319559, WO 9400959 and EP 0366342. EP0426269 describes a mobile system in which base stations are connected via routers to ATM network switches. Virtual connections controlled by the base stations are established between the base stations through the ATN network. Elementary mobility management is based on routing tables, which are maintained at base stations and in ATM switches and updated as subscribers move. GB2268359 and EP 679042 describe an ATM-access network in which there are permanent ATM virtual connections (to speed up the call set-up) between base stations and a mobile network interface, said connections being allocated for each call separately.
A possible future development trend is that mobile systems will have a broadband radio interface. In this case the transmission system of the mobile system should also be broadband, a potential alternative being provided by the ATM technology.
A third development trend is the introduction of wireless data transmission (wireless ATM) and mobility management into ATM networks. However, a problem arising from this is that current B-ISDN and ATM standards in no way support the mobility management, subscriber authentication, call control, etc., required by mobile communication. To introduce into the ATM network such supplementary characteristics required by mobile communication would therefore seem to require considerable development and standardization of and significant changes to the existing ATM systems. The implementation of wireless ATM would thus become a slow and an expensive process.
An object of the invention is to implement an ATM-transmission or an ATM-access network in a more flexible manner than before in mobile network architectures that conventionally use circuit-switched transmission systems.
Another object of the invention is to add wireless transmission and mobility to the ATM network, without significant changes to the existing ATM networks and standards.
An aspect of the invention is a telecommunication network, such as a mobile network, comprising mobile stations, base stations, at least one switching network element performing call control and switching, and an ATM switching function for a dynamic switching of virtual ATM transmission connections between the base stations and said at least one switching network element. The invention is characterized by said ATM switching function being arranged in said at least one switching network element and being controlled through an internal interface by a call control of the network element.
Another aspect of the invention is a wireless ATM network comprising mobile stations and at least one ATM switch to which base stations are connected through a network-to-user interface UNI. The invention is characterized by
the ATM network having at least one switching network element of another telecommunication network, such as a mobile network, to perform call control and switching control;
said switching network element being provided with an ATM switching function, which is controlled through an internal interface by the call control of the network element, for a dynamic switching of virtual ATM transmission connections between the base stations and said at least one switching network element.
A further aspect of the invention is a switching network element of a mobile network. The invention is characterized by the network element comprising an ATM switching function for a dynamic switching of virtual ATM transmission connections to base stations and by controlling the ATM switching function, through an internal interface, with a call control of the network element.
A still further aspect of the invention is a method according to claim 11.
In the invention a network element of a telecommunication network, such as a mobile network, which in conventional telecommunication network architecture performs the switching of circuit-switched connections, is provided with an ATM switching function. ATM switching functions are controlled by the same call control and switching control functions that are conventionally used e.g. for controlling a TDM switching field in a PLMN network element (Public Land Mobile Radio). In a minimum implementation, an ATM switching field provided with a suitable control interface is simply arranged in place of or parallel with the TDM switching field. The switching network element can thus be made, from the point of view of a physical and a logical interface layer, into one of the nodal points of the ATM network. As regards for instance PLMN-level signalling, mobility management and call control, the change is a transparent one, so said functions can be carried out applying solutions based on existing mobile networks and PLMN network elements, with only slight modifications. This reduces costs and enables even existing PLMN networks to be provided with an ATM transmission system. The invention also makes continuous evolution of the transmission system in telecommunication networks possible, because the use of ATM transmission can be further extended to other network elements, without changes being needed to higher level system solutions.
A telecommunication network element of the invention may comprise both a conventional TDM switching field and a new ATM switching field parallel with each other. This provides an advantageous solution for instance in a network evolution phase in which the telecommunication network comprises base stations or other network elements using both circuit-switched transmission and ATM transmission. The switching network element can in this situation be arranged to switch either a virtual ATM connection or a circuit-switched connection to a base station or other network element, depending on whether said base station or other network element supports ATM transmission or not.
The telecommunication network element of the invention functions in ATM layers according to ATM standards, signalling with other ATM devices (user terminals or ATM switches) in accordance with e.g. UNI signalling. The invention thus requires no changes to the ATM network signalling and its operation.
PLMN network elements of the invention can also be used for introducing mobility management and call control into a wireless ATM network. One or more PLMN network elements are arranged as a part of the ATM network and call control signalling is transparently transmitted through the ATM network. Since also the switching of virtual connections is performed in the PLMN network element, the rest of the ATM network is not required to have any features related to mobility management.
In a preferred embodiment of the invention, the PLMN element is connected to the ATM network through a UNI interface. The base stations are correspondingly connected to the ATM network through a UNI interface. The configuration of the ATM network can vary considerably. For instance, it is possible that each base station is connected through a UNI interface direct to a mobile services switching centre by an ATM switching function. For the mobile services switching centre the base stations are then ATM user terminals to which virtual connections can be switched. It is also possible that the base stations and the mobile services switching centre are connected to a base station controller by an ATM switching function through a UNI interface. For the base station controller the base stations and the mobile services switching centre are then ATM user terminals between which virtual connections can be switched. Both a mobile services switching centre and a base station controller may simultaneously comprise an ATM switching function.
The invention allows all special network elements and special functions related to wireless communication to be implemented into cellular radio networks using previously designed network elements and solutions. The designing of special solutions for a wireless ATM is thus avoided. The cellular network elements concerned are connected to the ATM network through a standard UNI interface, but the signalling between the cellular network elements takes place either transparently through the ATM network via said permanent virtual connections or separate signalling connections. The signalling related to wireless communication thus causes no changes in a standard ATM UNI protocol.


A combined plug and sealing ring for a sprinkler nozzle includes a nozzle plug having a substantially cylindrical portion adapted to engage within a nozzle orifice of a sprinkler nozzle, and a cap overlaying the substantially cylindrical portion. A sealing ring is adapted to seat onto a threaded pipe fitting portion of the sprinkler nozzle. A leash interconnects the nozzle plug and the sealing ring. A combined plug and sealing ring in combination with a sprinkler nozzle, and a method of installing a sprinkler nozzle in a highly corrosive or extremely corrosive environment are also disclosed.

Many industrial facilities, such as large metallurgical smelters, steel industry pickling lines, semiconductor fabrication facilities, pulp and paper plants, inorganic chemical facilities, and power generation plants, generate extremely corrosive exhaust fumes, smoke, and particles during their operational processes. Various ductwork systems can be employed to remove or filter these hazardous wastes from the facilities. The ductwork systems are typically fabricated from combustible plastics such as polypropylene, chlorinated polyvinyl chloride, and fiberglass reinforced plastic. The ducts can be up to twelve feet in diameter, and can be hundreds of feet long, with various interconnecting vessels. Loss of a ductwork system due to fire can result in total shutdown of a key process or the entire plant for an extended period of time, and can lead to sizeable losses.
The environment inside the ductwork systems is typically extremely corrosive. High concentrations of inorganic acids, such as sulfuric, nitric, and hydrochloric acids, are often present in the ducts. In addition, the temperature inside the ducts may be very high, sometimes 100° C. or higher, and abrasive particles, such as metal, dust, and ash, may pass through the ducts at a high velocity, for example 40 miles/hour, or more. Thus, the environment inside the ducts can rapidly corrode or otherwise damage metallic structures, such as fire protection components (e.g., sprinkler nozzles).
Sprinkler nozzles have been developed that can withstand the highly corrosive environments mentioned above, for example, the sprinkler nozzles described in applicant's co-owned U.S. Patent Application Publication No. 2008/0308285 A1, the entire content of which is expressly incorporated herein by reference.
In order to prevent corrosive gasses from entering the sprinkler nozzle and/or associated piping, it is advantageous to fit a plug inside the nozzle orifice. However, high flow rates and/or turbulence inside the ductwork systems can cause the plugs to become dislodged from the nozzle orifice, and lost. In addition, conventional plugs and their retention means may tend to deteriorate under highly corrosive and extremely corrosive conditions. Furthermore, the sprinkler nozzle threads utilizing conventional sealing methods are vulnerable to corrosion and may tend to deteriorate under highly corrosive and extremely corrosive conditions. Accordingly, there remains a need in the art for nozzle plugs, sealing rings, and leashes that overcome these and other drawbacks of the prior art.

Combined plug and sealing ring for sprinkler nozzle and related methods


There is provided a liquid agrochemical composition having a stable water-diluted state, which comprises 0.5 to 30% by weight of one or more hydrophobic agrochemical active compounds, 1 to 20% by weight of one or more nonionic surfactants selected from the group consisting of a polyoxyethylene polyoxypropylene block copolymer and the like, 0 to 10% by weight of one or more anionic surfactant, 6 to 60% by weight of γ-butyrolactone, and 20 to 75% by weight of 1,3-dimethyl-2-imidazolidinone; and water-diluted solution obtained by diluting the liquid agrochemical composition with a 10 to 10,000-fold amount of water.

The present invention relates to a liquid agrochemical composition containing a hydrophobic agrochemical active compound.
Representative examples of a liquid agrochemical preparation containing a hydrophobic agrochemical active compound include emulsions and flowables. When emulsions or flowables are sprayed, they are used as a water-diluted solution by diluting with a large amount of water. In such a water-diluted solution, a hydrophobic agrochemical active compound is such that fine oil droplets or solid particles are dispersed in water by the action of a surfactant, and since this state is a thermodynamically unstable state, oil droplets containing the hydrophobic agrochemical active compound are separated with time and, when the hydrophobic agrochemical active compound is a solid, solid particles are precipitated and settled in some cases.
JP 2003-128501 A describes a liquid agrochemical preparation containing quizalofop-p-ethyl, which is a hydrophobic agrochemical compound, polyoxyethylenestyryl phenyl ether, dodecylbenzene sulfonic acid salt, Solvesso 200 and 1,3-dimethyl-2-imidazolidinone, but the liquid agrochemical preparation is not necessarily stable in the water-diluted state.

Liquid agrochemical composition containing hydrophobic agrochemical active compound


To permit the use of combustible and potentially explosive solvents used in dry-cleaning operations, based on hydrocarbon compounds, the dry-cleaning machine is formed with an explosion-resistant housing (8) surrounding a perforated, rotatable drum (1) into which the goods are introduced. After carrying out the normal dry-cleaning procedure, and draining of dry-cleaning solvent, a vacuum pump generates an under-pressure, in the order of below 500 mbar, and preferably about 230 mbar, while heating the mixture to effect drying. A cooling coil, located at a lower portion of the machine, provides for condensation of solvent out of the solvent-air mixture and, after the major portion of the solvent has been evaporated, the heat exchanger is switched over to cooling for final condensation of any remanent solvent. The vacuum continues to be maintained, so that the boiling point of solvent, due to the under-pressure, is lowered by at least 40.degree. C., and preferably 50.degree. C. or more, below the boiling point at ambient air pressure, so that explosions are reliably prevented and, if they should occur nevertheless, the explosive force is substantially decreased since the starting pressure of the explosive force is already substantially below atmospheric pressure.

Chemical cleaning installations for textiles, hereinafter for short "dry-cleaning apparatus" as well as dry-cleaning methods, usually use solvents and cleaning substances such as chlorinated hydrocarbons; perchlorethylene (PCE) is a common cleaning agent. Such dry-cleaning agents are suitable, they are non-combustible, and not explosive. They do, however, have a substantial disadvantage in that these solvents, when evaporating, detrimentally affect the ozone layer surrounding the earth. Additionally, they are somewhat toxic and long-term handling is dangerous to the health of the operators. Efforts have been made to replace the well known chlorinated hydrocarbon cleaning agents with solvents or cleaning agents which are environmentally acceptable and benign, non-toxic, and not detrimental to operators handling freshly dry-cleaned goods, typically garments, or other textile materials. The dry-cleaning agents must, additionally, meet environmental protection laws and regulations, as well as health laws and regulations instituted by governmental authorities.
Difficulties have been encountered in converting apparatus used in dry-cleaning with hydrocarbons to be useful with non-toxic agents since dry-cleaning agents which meet the requirements of environmental and health acceptability known in the industry are, unfortunately, combustible and, under some conditions, the gases emitted therefrom are potentially explosive. Consequently, conventional dry-cleaning machinery and methods cannot be used with dry-cleaning agents of this type.

Dry-cleaning apparatus permitting use of ignitable or potentially explosive solvents


An electric motor includes an armature shaft which is mounted in at least one floating bearing. The floating bearing comprises a bearing inner ring, which is positioned on the armature shaft, a bearing outer ring, which is received in a bearing seat, and a fluid pump for a vehicle fluid system having the electric motor. Lubricant disposed between the armature shaft and the bearing inner ring forms a hydrodynamic lubricant film and generates a constant relative movement between the armature shaft and the bearing inner ring.

Electric motors of the abovementioned type are frequently used as a drive for hydraulic pumps in vehicle hydraulic systems, such as anti-lock brake systems (ABS) or traction control systems (ASR system) or electronic stability program systems (ESP system). Electric motors of this type comprise various bearing arrangements for mounting an armature shaft both in the radial and in the axial direction. Said bearing arrangements usually have both what are known as locating bearings and also what are known as floating bearings. Said bearing arrangements frequently cause undesired noise development during the operation of the electric motor.
The laid-open specification DE 10 2006 042 340 A1 describes, for example, an electric motor with an armature shaft which is received in a bearing arrangement. Here, the armature shaft is mounted in at least one floating bearing which comprises a bearing inner ring which is arranged on the armature shaft and a bearing outer ring which is received in a bearing seat.


Distributed data processing systems that provide services at two network addresses have their interfaces described in a published interface description document available at a Uniform Resource Locator (“URL”). The interface description of the second of the services replaces the interface description of the first of the services. Related methods, computer readable media, and systems to benefit from an embodiment of the invention are also described and claimed.

Contemporary data processing activities are frequently distributed among a number of independent computer systems that use a communication fabric such as a local- or wide-area network to coordinate their operations. This model of data processing is generally more complex and somewhat less efficient than older arrangements where a complete, clearly-defined processing operation occurs at a single system and a "finished" data product may be transmitted to another location. In a distributed system, it is not uncommon for portions of closely-linked processing sequences to occur on different systems, with both partially-processed data and executable code passing between the systems over a communication link.
Various advantages are available from distributed processing. For example, computationally expensive or time-consuming operations can be consolidated and performed by a system designed specifically to perform those operations quickly; competing providers of standardized processing can establish a market to provide the services at a range of price/performance points; and decoupling phases of a processing sequence can make it easier to design robust systems that can continue operation despite failures of individual machines or communication links.
One difficulty that arises in designing and operating distributed data processing systems is in specifying the interfaces through which cooperating processing elements will communicate. Standards such as the Common Object Request Broker Architecture ("CORBA") by the Object Management Group ("OMG") consortium and the Web Services Description Language ("WSDL") by the international World Wide Web Consortium ("W3C") provide a great deal of guidance in this area, but even assuming that all interoperational difficulties that are common to distributed systems could be addressed by the standards, challenges arising from the lack of centralized control of all the components of a distributed system remain. That is, in a process that involves operations and services sourced from different providers, changes in an underlying service can disrupt the overall process. Methods of advertising and providing services that avoid disruptions while still permitting the service provider to change, enhance or repair the service may be of value in this field.

Method and apparatus for mapping an appropriate service version for a client


Apparatus for restraining and transporting dies in punch press operations is provided. A floatation platen for supporting a die on the platen's upper surface has a plurality of recessed gas exhaust ports on the platen's lower surface. A source of pressurized gas delivers gas to a platen manifold, for delivery to orifices located in the gas exhaust ports. The flow of gas is controlled by a first valve adjacent the gas source and a second valve adjacent the manifold, with the second valve being used to control the gas flow during movement of the die. In this fashion, a die may be moved on a cushion of air from one workstation to a selected second workstation. A moveable hydraulically operated restraining fixture is also provided, for clamping the die in position during the compacting phase, and for releasing the die after completion of the compacting phase by releasing the hydraulic pressure on the restraining fixture. When pressure in the hydraulic cylinders on the restraining fixture is reversed, the restraining fixture will retract so that there is no contact between the die and the restraining fixture, thereby allowing the die to be removed from a first workstation and moved to a second selected workstation.

Presently known apparati for restraining and removing dies in a punch press operation utilize a fixed-width restraining fixture and a die carriage which transports the die into and out of the restraining fixture. It also commonly utilizes a series of rack and pinion drive shafts, shear pins, a drive motor clutch, and a carriage, in addition to the restraining fixture necessary to hold the die while compaction takes place. The die will expand under the heavy pressure applied during compaction. However, the restraining fixture restrains the die, leaving it wedged in place when compaction is completed and the upper ram returns to its home position. Removing the die from the restraining fixture is then accomplished by using the die carriage. The lateral forces exerted against the fixed-width restraining fixture are extreme, and it requires high torque to release the die from the restraining fixture and propel it to the next work station. Breakdowns are frequent and often difficult to repair. In addition, the die assemblies weighing as much as 75-85 pounds must be physically pushed and moved from one location to another. These problems are all greatly exacerbated when working with highly toxic materials requiring the use of a glove box to isolate the operator from the workpiece.
U.S. Pat. No. 4,810,458 to Oshima et al. is representative of many patents wherein a floating air cushion or the like is used to support a workpiece. Oshima discloses a ceramic body which is continually extruded through a die of an extruder and is supported by a porous support, in a slightly floating state, by air pressure provided through pores of the support. U.S. Pat. Nos. 4,828,769 and 4,900,242, both to Maus et al, each disclose an apparatus for injection molding of articles, including a movable platen assembly. However, none of the known art solves the problems of restraining the die without binding, and of moving the die without elaborate machinery and heavy force requirements.
It is thus desirable to provide an apparatus which allows for ease of removal of a die after the completion of the compaction phase, while nonetheless still providing firm support for the die during the compaction phase. In addition, it is desirable to provide an apparatus which allows a die to be easily moved with minimal power and mechanical aid from one work station to the next in punch press operations. It is particularly important to provide apparatus allowing for these advantages when working with highly toxic materials requiring the use of a glove box, and where a high degree of automation may be desired.

The United States of America as represented by the United States Department of Energy

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A light-emitting diode driving apparatus including a rectifying circuit, a switching element, a choke coil, an output current sensing circuit, an LED light source, a rectifier diode, a control circuit, and a feedback sensing circuit which is connected to the output current sensing circuit for receiving an output feedback signal output from the output current sensing circuit, wherein the feedback sensing circuit outputs a feedback dummy signal, and outputs to the control circuit a control signal that controls switching of the switching element in response to a signal based on an error between the output feedback signal and the feedback dummy signal.

In recent years, light-emitting diode driving semiconductor devices for driving a light-emitting diode (hereinafter, referred to as an LED) and light-emitting diode driving apparatuses having the same are developed and put in practical use. In particular, a large volume of lighting devices, such as an LED bulb having a white LED as a light source, are manufactured. Moreover, various driver circuits which properly drive an LED are proposed (e.g., see Patent Literatures (PTLs) 1 to 3).
A conventional light-emitting diode driving apparatus disclosed in PTL 1 is an apparatus which has a non-isolated flyback converter circuit structure, and includes a transformer for transforming a DC voltage into energy.
A conventional light-emitting diode driving apparatus disclosed in PTL 2 has a buck converter circuit structure. For example, the light-emitting diode driving apparatus includes a buck converter which includes a switching element Q21, a driver circuit 213, a rectifying element D22, a choke coil L23, and a smoothing condenser C24. Here, the buck converter is, particularly, a high-side buck converter in which a switching element is disposed on the high side of an input voltage.
To construct a non-isolated circuit, the use of a buck converter is advantageous in efficiency or cost, as compared to a flyback converter.
A conventional light-emitting diode driving apparatus disclosed in PTL 3 includes a buck converter as with PTL 2. The buck converter is, particularly, a low-side buck converter in which a switching element is disposed on the low side (reference potential) of an input voltage.

Light-emitting diode driving apparatus and semiconductor device

Panasonic Intellectual Property Management Co., Ltd.


A method, system and computer-usable medium for configuring UE-specific A-SRS subframes. More specifically, UE-specific Aperiodic Sounding Reference Signal (A-SRS) subframes are defined only within a radio subframe.

1. Field
The present invention is directed in general to communications systems and methods for operating same. In one aspect, the present invention relates to devices and methods for aperiodic SRS subframe configuration and signaling.
2. Description of the Related Art
In known wireless telecommunications systems, transmission equipment in a base station or access device transmits signals throughout a geographical region known as a cell. As technology has evolved, more advanced equipment has been introduced that can provide services that were not possible previously. This advanced equipment might include, for example, an E-UTRAN (evolved universal terrestrial radio access network) node B (eNB), a base station or other systems and devices. Such advanced or next generation equipment is often referred to as long-term evolution (LTE) equipment, and a packet-based network that uses such equipment is often referred to as an evolved packet system (EPS). An access device is any component, such as a traditional base station or an LTE eNB (Evolved Node B) that can provide user equipment (UE) with access to other components in a telecommunications system.
In mobile communication systems such as an E-UTRAN, the access device provides radio accesses to one or more UEs. The access device comprises a packet scheduler for allocating uplink (UL) and downlink (DL) data transmission resources among all the UEs communicating to the access device. The functions of the scheduler include, among others, dividing the available air interface capacity between the UEs, deciding the resources (e.g. sub-carrier frequencies and timing) to be used for each UE's packet data transmission, and monitoring packet allocation and system load. The scheduler allocates physical layer resources for physical downlink shared channel (PDSCH) and physical uplink shared channel (PUSCH) data transmissions, and sends scheduling information to the UEs through a control channel. The UEs refer to the scheduling information for the timing, frequency, data block size, modulation and coding of uplink and downlink transmissions.
In certain communication standards, such as the 3GPP (3rd Generation Partnership Project) communication standard, uplink spatial multiplexing of up to four layers may be supported by LTE-Advanced. Prior to supporting spatial multiplexing, only a single-antenna port mode of operation was available for the uplink. Thus, the methodology defined in earlier releases of the 3GPP communication standard (e.g., 3GPP Releases 8 and 9) for obtaining channel state information was designed to only measure the channel between a single uplink transmission antenna and the eNB within any single subframe. To support the new uplink MIMO capabilities, it is desirable for the next release of the 3GPP communication standard (e.g., 3GPP release 10) to allow simultaneous channel sounding from multiple UE transmission antennas. Because each uplink transmission antenna requires its own set of orthogonal sounding resources, a new more-efficient sounding methodology is desirable for this next release.
The method used for sounding the channel for the earlier release UEs was known as periodic sounding since this method configures each Radio Resource Control (RRC) Connected UE to transmit a known signal at periodic intervals so that the eNB can measure the channel. Consequently, each UE consumes a fixed amount of resources for that transmission periodically (e.g., every 10 ms) regardless of whether the UE has uplink data to convey or not. To improve the efficiency in the next release, a new aperiodic sounding methodology (i.e., a sounding methodology of irregular occurrence) is being defined which allows the eNB to command the UE to perform aperiodic sounding only when it is required by the eNB. This aperiodic sounding methodology will likely improve efficiency since it will allow the resources to be consumed only when it is beneficial to do so (e.g., only when the UE has uplink data to convey). The new aperiodic sounding methodology is being defined as a complementary mechanism for 3GPP Release 10 and later UEs. The methodology can be used in conjunction with the legacy periodic sounding mechanism in a process where the periodic sounding is configured for each Release 10 RRC Connected UE, but with a longer period (e.g., 20-40 ms or longer) to provide the eNB some information regarding the channel to maintain timing alignment, adjust the UE power control, etc, and then the aperiodic sounding methodology is used to obtain more frequent channel state updates as needed once data comes into the uplink buffer.
In a LTE Release-8 system, the eNB may configure the periodic sounding methodology for a UE to transmit SRS in just one subframe or periodically in multiple subframes. One purpose of a Release 8/9 sounding reference signal (SRS) transmission is to help the eNB estimate the uplink channel quality to support frequency-selective uplink scheduling. In addition, SRS may also be used to control uplink power or uplink timing advance.
Channel sounding is a method used in wireless communication systems to obtain uplink channel state information (CSI) for assigning modulation and coding schemes (MCS), selecting rank and antenna precoding matrix in case of multiple Input and Multiple Output (MIMO) operation, and for frequency selective scheduling for uplink transmission. A known sounding signal waveform is typically transmitted between a transmitter and a receiver, and the channel state information is estimated at the receiver based on the known sounding signal. In 3GPP LTE Release 8, a sounding reference signal (SRS) is typically transmitted periodically from each RRC_CONNECTED UE to the eNB to facilitate uplink timing correction, scheduling and link adaptation. The last symbol of a subframe configured for SRS transmission is used for SRS transmission in LTE Frequency Division Duplexing (FDD) systems as shown in FIG. 1. In LTE, uplink transmissions are organized into radio frames each include 10 subframes ranging from subframe 0 to subframe 9. A subframe is further divided into two slots. In addition, radio frames are indexed from 0 to 1023 and each of the indexed radio frame is referred to as a system frame.
In 3GPP Release 8, cell-specific SRS resources are defined in both frequency and time domains in terms of SRS period, subframe offsets, and SRS bandwidth and are semi-statically configured through RRC signaling in a cell. The cell specific subframe configuration is shown in FIG. 2, and the sounding reference signal subframes are the subframes satisfying └ns/2┌modTSFCεΔSFC, where ns=0, 1, . . . , 19 is the slot index within a frame. For example, the cell-specific SRS subframes when srs-SubframeConfig=0 are the subframes {0,1, 2, 3, 4, 5, 6, 7, 8, 9}, (i.e. all the subframes in each radio frame). In another example, the cell-specific SRS subframes when srs-SubframeConfig=2 are the subframes {1, 3, 5, 7, 9}.
In 3GPP Release 8, SRS bandwidth configuration is shown in FIG. 2 for a system bandwidth between 40 and 60 Resource Blocks (RBs), where one RB includes 12 subcarriers. For a given cell specific SRS bandwidth configuration index CSRS, the absolute SRS bandwidth for a UE-specific bandwidth configuration BSRS depends on the system bandwidth. SRS bandwidth configurations for other system bandwidths can be found in the 3GPP specification. Each UE is assigned semi-statically with a UE-specific periodic SRS resource determined by a UE-specific SRS bandwidth, BSRS, a frequency domain position, nRRC, a transmission comb, kTC, a cyclic shift (CS), a subframe period, TSRS, and a subframe offset, Toffset. In Rel-10 multiple configurations are also supported for UE-specific aperiodic SRS transmissions, which can be triggered by a uplink data grant.
In 3GPP Release 8, UE-specific periodic SRS subframe configuration (subframe period and offset) in LTE FDD is shown in FIG. 3, where the SRS subframes for a UE are the subframes satisfying (10·nf+kSRS−Toffset)modTSRS=0, where nf is the system frame number, and kSRS={0, 1, . . . , 9} is the subframe index within the frame.
In 3GPP Release 10, up to four UE Tx antennas are supported for uplink MIMO. Since separate SRS resources are needed for each Tx antenna, there can be a shortage of SRS resources. To address this issue, aperiodic SRS (A-SRS) has been introduced in which SRS can be dynamically scheduled or triggered by an eNB in an as needed basis through uplink data grants. It has been agreed that similar to the periodic SRS case, each UE is also assigned with a UE-specific A-SRS subframe configuration, i.e. subframes in which A-SRS can be scheduled or triggered. Accordingly, it would be desirable to provide a configuration of UE-specific A-SRS subframes.
One possibility would be to adopt the Release 8 UE-specific periodic SRS subframe configuration as shown in FIG. 4. An issue with this type of configuration is that the configuration limits the A-SRS subframes for a UE to periodical subframes with possible periodicities of 2 ms, 5 ms, 10 ms and so on. This reduces the available opportunities for A-SRS transmission. For example, when the cell-specific SRS subframe configuration of 13 or 14 is used as shown in FIG. 2, the minimum period for UE-specific A-SRS subframes is 5 ms for the odd subframes even though there are 7 or 8 subframes available for SRS transmission within a radio frame. Thus it limits two adjacent A-SRS transmissions to at least 5 ms for UEs configured on those odd subframes.

Method for aperiodic SRS subframe configuration and signaling


The invention discloses a trailing edge (2) of an aircraft aerodynamic surface, which comprises an upper skin (6) and a lower skin (7), being the upper and lower skins (6, 7) made of composite material. In the trailing edge (2) a lightweight part (1) is assembled at an end section (13) of the upper and lower skins (6, 7). The lightweight part (1) is covered by a metallic sheet (8), and has a “V”-shaped cross section with arms and peak, where the peak of the “V”-shaped cross section has a rounded shape and is located opposite the end section (13) of the upper and lower skins (6, 7).

The skins of an elevator, in Long Range (LR) & Single Aisle (SA) type aircraft, are manufactured with sandwich type composite materials.
Sandwich type composite material skins are manufactured by attaching two thin, but stiff skins (typically made from carbon fibre reinforced plastic laminates) to a lightweight but thick core (usually open and closed-cell structured foams). The core must have a minimum thickness in order to withstand the pressure transferred by the carbon fibre reinforced laminates during the curing cycle wherein a high temperature and pressure is applied; otherwise the core would collapse under said pressure.
Trailing edges of aircraft structures are formed by joining the upper skin and the lower skin of said aircraft structure. The thickness of the upper skin and of the lower skin decreases in the area of the trailing edge, in order to achieve the desired aerodynamic profile.
When the upper skin and the lower skin of said aircraft structure are made of sandwich type composite materials, due to the minimum core thickness requirement for each skin, there is a change in the slope of the upper skin and the lower skin, which worsens the aerodynamic profile of the aforementioned trailing edge.
In order to achieve a continuous aerodynamic profile, the upper and lower skins are currently joined by a clip type metal sheet, with a U-shape and the remaining space is filled with a paste until the desired continuous aerodynamic profile is obtained. This paste, when used in a huge quantity, becomes chapped and falls off the stabilizers, carrying, with the falling off of the paste, the paint of the aircraft. This falling off increases the profile drag and the falling off is an esthetic drawback that is the cause of many complaints from airlines.
Document WO 2010/070185 A2 discloses a trailing edge structure according to the prior art, in which the upper and lower skins are joined by a clip-type element with recesses where the inner surfaces of both the upper skin and the lower skin are coupled to said element, placing a paste on the clip-type element until the aerodynamic desired profile is obtained.

Trailing edge of an aircraft aerodynamic surface


A sense amplifier for nonvolatile memory cells includes a reference cell, a first load, connected to the reference cell, and a second load, connectable to a nonvolatile memory cell, both the first load and the second load having controllable resistance; a control circuit of the first load and of the second load supplies the first load and the second load with a control voltage irrespective of an operating voltage between a first conduction terminal and a second conduction terminal of the first load.

1. Field of the Invention
The present invention relates to a sense amplifier for low-supply-voltage nonvolatile memory cells.
2. Discussion of the Related Art
As is known, the reading of nonvolatile memory cells is normally based upon the comparison between the currents flowing through a selected memory cell (cell to be read) and a reference memory cell, biased with equal gate-source and drain-source voltages.
In practice, in known sense-amplifier circuits, the cell to be read and the reference memory cell are coupled to respective load transistors, which are connected to one another in a current-mirror configuration and hence have equal gate-source voltage. The currents flowing in the cells are thus converted into voltages, which are then directly compared by a comparator circuit having inputs connected to the drain terminals of the load transistors.
The traditional architecture in a current-mirror configuration, typically used for connection between the load transistors, limits, however, the performance of the known sense-amplifier circuits and, above all, causes their use to be critical in presence of low supply voltages.
In fact, in order to conduct a sufficient current, the load transistors must have a gate-source conduction voltage that is equal, in absolute value, to the sum of a threshold voltage and a so-called overdrive voltage. With reference to the typical case of load transistors of a PMOS type, with source terminals connected to a supply line, in both of the load transistors the gate terminal must be at a voltage lower than the supply voltage by an amount equal to the conduction voltage.
Furthermore, one of the load transistors (normally the one associated with the reference cell) is dioded connected, i.e., it has drain and source terminals directly connected to one another. It is thus evident that also the drain terminal is biased at a voltage equal to the supply voltage decreased by the conduction voltage.
Such a constraint, however, is scarcely compatible with the supply voltages currently used and, above all, conflicts with the need, which is increasingly felt, to reduce the supply voltages in order to minimize power consumption. The voltage on the gate terminal of the load transistors must in fact be sufficient to guarantee correct operation also of the cell to be read and, in particular, of the reference cell, which is in the most critical condition. Furthermore, also other components, which are normally cascaded between the drain terminal of the load transistor and the reference cell, must be biased with a sufficient voltage. In particular, there are usually provided a stage for regulating the drain voltage of the reference cell; and so-called "dummy" transistors, which reproduce on the side of the reference cell the effect of the column-decoder circuits.
As an example, consider a sense amplifier which receives a supply voltage of 1.8 V and is provided with a load transistor having a threshold voltage of 0.5 V and operating with an overdrive voltage of 0.3 V. In this case, the gate-source conduction voltage is equal to approximately 0.8 V, and thus the drain terminal of the diode-connected load transistor is at approximately 1 V, i.e., at the border of proper operation conditions. It is evident that even modest disturbances or thermal variations can readily cause malfunctioning.

Sense amplifier for low-supply-voltage nonvolatile memory cells


A device for producing a curved fiber preform from a bi- or multidirectional fiber semi-finished product, in particular for an aircraft or spacecraft fuselage component has first lamellae and second lamellae formed to be couplable to one another criss-cross such that they are positioned on a shared plane and thus form a grid. The lamellae at least in part are formed resiliently bendable about an axis intersecting the shared plane such that a local orientation of the lamellae in the grid changes. An adhesion device or structure is formed for temporarily adhering the fiber semi-finished product and is configured such that the local fiber orientation of the fiber semi-finished product also changes accordingly when the lamellae bend.

For producing former structures, textile blanks of a bi- or multidirectional fiber semi-finished product are draped onto the desired former shape. The draping is currently usually carried out by hand. A necessary step in this context is the production of the former-specific curvature so as to obtain a curved fiber preform. For this purpose, shearing and/or deformation of the fiber semi-finished product are generally required. Further, adaptation to the precise shape of each individual component to be produced is also carried out, in particular subsequently.
DE 10 2011 119 220 A1 describes devices for producing curved components from a fiber composite material.

Device and method for producing a curved fiber preform from a bi-or multidirectional fiber semi-finished product


A linear actuator for positioning the heads of a disk file relative to tracks on the disks employs a ceramic material having wear properties superior to steel in guide surfaces for guiding a head supporting carriage running on rotary bearings in contact with the guide surfaces. The preferred ceramic material is tetragonally stabilized zirconia.

This invention relates to linear actuators for positioning the heads of disk files.
Transducing heads for reading information from and writing information on the information storage disks of a disk file must be accurately positioned over selected concentric information bearing tracks on the disk surface. Various types of actuator have been employed to position the heads of which the most common is the linear voice coil actuator.
This comprises a coil which is situated in a annular air gap in a magnet assembly such that energization of the coil causes it to move linearly along the air gap. The coil is connected to and supported by a carriage which also supports the heads. The carriage runs on guide ways or surfaces which constrain it to move in a linear path radially of the disks.
A recent example of such an actuator can be found in U.S. Pat. No. 4,661,729. In that patent the guide ways are horizontally spaced parallel rods between which the carriage runs on three pairs of outrigger bearings. The conventional material for such guide rods is steel and an example of another such actuator in which steel is specified as the guide rod material is described in published European patent application EP 0223610 A2.
The use of magnetic steels to form guide rods has been recognized to have potential disadvantages in the case of voice coil actuators since their magnetization by the voice coil magnet assembly can affect actuator performance by causing the carriage bearings, if also magnetic, to "cog" or run unevenly. In the case of magnetic disk files, the prior art has also recognized the problem that magnetic guide rods may also offer a leakage path for magnetic flux to the neighborhood of the disks, thus affecting the read and write process. One solution to these problems is the use of non-magnetic stainless steel guide rods and a linear VCM employing such guide rods is described in U.S. Pat. No. 4,247,794.
The use of non-magnetic guide rails or bearings is also mentioned in an article by K. A. Mawla (IBM Technical Disclosure Bulletin, Vol. 28 No. 10, March 1986, p. 4479) entitled "Magnetic shunts to shield the bearings and rails of a voice coil motor actuator in a magnetic recording disk file", as a possible alternative to the use of such shunts.
An article entitled "Composite center core for reduction of stray magnetic fields in disk file actuators" by J. Cocke et al. (IBM Technical Disclosure Bulletin Vo. 28, No. 5, Oct. 1985, p. 1889) suggests a guide rod center core comprising a non-magnetic rod, such as stainless steel, soldered to a magnetic rod within the actuator stator.
A further problem with guide ways for linear actuators which is not discussed in the above referenced art is that of wear. Although the use of flat guide ways is known to reduce wear by spreading the load of the bearings, this requires precision alignment of the bearings with the flat guide surface which is difficult and costly to achieve. Thus in most recent disk files, round ways are preferred.
Wear of the carriage guide way surfaces, whether flat or round, can lead to tilting of the carriage in the direction of motion and consequent non-linear radial movement of the magnetic heads on the disk surfaces. Although such displacements can be accommodated to a limited extent by the head positioning servo system, the misregistration may exceed the limits that the servo can follow and, in any case, will limit the attainable track density.
The problem of tilt in linear actuator systems becomes more acute with smaller form factor disk files. This is because the wheelbase of the carriage is reduced and, by the principle of levers, the movement of the heads resulting from a small displacement of one of the bearings will be amplified.
Another aspect of wear which is particularly critical in disk files is that it is a source of particulate debris which can cause failure of the heads/disk interface where separations of 0.3 are typical.
As well as their better known uses as refractory or electrical insulating materials, ceramics such as zirconia have been proposed for a number of engineering applications involving wear under light loads or hot conditions. A number of such applications, as well as a general review of zirconia, are discussed in "An introduction to zirconia" by R. Stevens (Magnesium Elektron Ltd., 1986).
In a recent U.S. Pat. No. 4,709,284, zirconia is suggested as a material for the air bearing slider of a magnetic head because of its good sliding properties, abrasion resistance, high machinability and resistance to static electrical charging.

Linear actuator with reduced wear guide way

International Business Machines Corporation


A gate locking device for a fence which includes a security box having a mounting plate affixed within the box. The security box is mounted to a pole of the fence. An oarlock is hingeably mounted within the security box. The oarlock is capable of movement between an unlocked position and a locked position. In the locked position the oarlock engages another pole of the fence. A dead bolt is securely affixed to the mounting plate within the security box and is movable between an extended and unextended position. The dead bolt is disposed in mechanical relation to the heel plate of the oarlock so that when the dead bolt is moved to the extended position it substantially prevents the pivotal movement of the oarlock. A barrel lock is mounted to the security box and mechanically connected and adapted to the dead bolt for moving it between the extended and unextended position. When the oarlock is moved to the locked position and the dead bolt is moved to the extended position the oarlock can not be moved back to the unlocked position and the gate is securely locked to prevent unauthorized intrusion.

1. Field of the Invention
This invention relates to a gate lock for a chain link fence, and more particularly, to a high security gate lock for chain link fences.
2. Prior Art
Chain link fences are well known. Typically such fences include a frame having numerous poles disposed at fixed intervals which support a mesh of thick metal wire which forms a screen. The screen is secured to the poles by pieces of wire. To provide a gate in an opening between two poles of a chain link fence, the gate being about the size of the opening is hinged to a pole on one side of the opening. An oarlock or fork latch is hingeably attached to the opposite pole of the gate frame. When the gate is in the closed position, the oarlock or fork latch is moved to the horizontal position where it receives the pole o the fence in the U-shaped portion thereof.
To lock the gate when the oarlock is in the closed position, i.e. horizontal, openings in the lock and collar are provided which line up, and a padlock is passed through the openings to lock them in their aligned position. With the lock in place, the oarlock cannot be moved from the horizontal closed position to the vertical open position. Thus the gate is locked.
The drawbacks of such a method of locking a chain link gate includes difficulty in opening and closing the lock and gate, the potential to lose or misplace the lock, and the inherent weakness of an oarlock or fork latch to tampering by an intruder. Loss of the lock occurs frequently because the padlock has to be removed from the gate to complete the locking and unlocking operation. Further, in order to unlock the gate two hands must be used, one hand to hold and steady the lock and another hand for inserting the key to open the lock.
U.S. Pat. No. 4,691,541 to the inventor herein, McQuade (hereinafter "McQuade '541") eliminates the risk of losing or misplacing the lock because the locking device is always attached to the gate frame. At no time is the lock removed from the gate to complete its operation. Operational ease is attained because the lock is stationary and the key slot is accessible. To open the lock simply insert the key and turn. When the key is turned, the lock cylinder will pop out and release the lock bar from the oarlock. To lock the gate, the oarlock is moved to its horizontal, locking position and a push button cylinder is engaged to move its lock bar into an opening in the oarlock to fix the oarlock in position.
In McQuade '541 the collar holding the lock and oarlock is modified from that typically used to retain an oarlock. The collar is in two pieces and sandwiches the pipe of the gate frame. Set screws pass through the collar causing the collar to engage the trame pipe. The lock system is comprised of several parts, and each of the parts is easily replaceable permitting quick repair. The lock provides a child proof gate lock with ease of installation. The lock is always in its proper locking position and cannot be misplaced.
The McOuade '541 gate lock works very well for its intended use as a low security gate lock, but the locking mechanism can be pulled out of the gate lock assembly by one who wishes to breach the security of the chain link fence.

Gate locking device featuring dead bolt means


A method of fabricating a III-N device includes forming a III-N channel layer on a substrate, a III-N barrier layer on the channel layer, an insulator layer on the barrier layer, and a trench in a first portion of the device. Forming the trench comprises removing the insulator layer and a part of the barrier layer in the first portion of the device, such that a remaining portion of the barrier layer in the first portion of the device has a thickness away from a top surface of the channel layer, the thickness being within a predetermined thickness range, annealing the III-N device in a gas ambient including oxygen at an elevated temperature to oxidize the remaining portion of the barrier layer in the first portion of the device, and removing the oxidized remaining portion of the barrier layer in the first portion of the device.

Most power semiconductor devices, e.g., high-voltage P-I-N diodes, and power transistors, e.g., power metal-oxide-semiconductor field-effect transistors (MOSFETs) and Insulated Gate Bipolar Transistors (IGBTs), have been typically fabricated with silicon (Si) semiconductor materials. Silicon carbide (SiC) power devices have also been used. III-N devices are attractive semiconductor devices to carry large currents and support high voltages, and provide very low on resistance, high voltage operation, and fast switching times.
Some III-N devices, e.g., high electron mobility transistors (HEMTs) and bidirectional switches (also known as four quadrant switches or FQSs), may be depletion-mode (or D-mode) or normally-on devices, e.g., devices with a negative threshold voltage. That is, the devices are in the ON state unless a sufficiently negative voltage is applied to the gate electrode relative to the source or power electrode. In many applications, in particular in power switching circuits, it is desirable to utilize enhancement-mode (or E-mode) devices, e.g., devices with a positive threshold voltage, as this can simplify the form of the signals applied by a gate-drive circuit to the device and can prevent accidental turn on of the device in case of device or circuit failure. Reliable fabrication and manufacturing of high-voltage III-N E-mode devices has proven to be very difficult. In some cases, a high-voltage III-N D-mode device and a low-voltage silicon-based E-mode device are combined together to form a hybrid device, which may achieve the same or similar output characteristics as a single high-voltage III-N E-mode device.

Forming enhancement mode III-nitride devices


Dithioether-linked phthalonitrile monomer are prepared by a substitution reaction between 4-nitrophthalonitrile and a dimercaptan and are polymerized to a high-temperature, oxidation-resistant polymer by heating them at a temperature above their melting point. The rate of polymerization is increased by the addition of an amine. Electrical conductivity of the polymer can be increased to the conductor range by heating the polymer above about 400.degree. C.

This invention relates generally to the synthesis and polymerization of phthalonitrile monomers, and, more particularly to the synthesis, polymerization and pyrolization of dithioether-linked phthalonitrile monomers.
Phthalonitrile monomers have two phenyl dinitrile groups connected by a linking group. The linking group in the monomer becomes the linking group in the polymer. The properties of the polymer are determined to a large degree by the linking group. Heretofore, the linking group has been generally hydrocarbons, phenoxy, alkoxy or sulfone moieties.
Examples of previous phthalonitrile monomers and polymers demonstrate the versatility and importance of this growing class of materials. Keller, in the U.S. Pat. No. 4,234,712, used sulphone and ketone groups to link phthalocyanines, thus forming high temperature structural composites and adhesives. Similarly, Keller, in U.S. Pat. No. 4,238,601, used perfluorinated alkyl substituents on the linking and phenyl groups to increase the corrosive resistance of polymerized phthalocyanines. Polyphenylether-bridged polyphthalocyanines were prepared by Keller, U.S. Pat. No. 4,259,471, which exhibited exceptional thermal stability and oxidative resistance. Also, by varying the fluoride content of the constituent and substituent groups of the linking group, Keller, in U.S. Pat. No. 4,315,093, produced a phthalonitrile polymer with improved water repellancy and resistance to oxidative attacks. The performance of the polymers have exceeded polyoxides, epoxies and other similar polymers in many applications.
One property of high-temperature organic materials that is of great interest is electrical conductivity. Materials with high conductivities have been obtained by either chemical doping of a linear conjugated system or by thermal treatment of polymers. In the case of chemical doping, the conductivity of a polymer is varied and controlled by the amount of dopant used. For thermal treatment, the conductivity of a polymer is changed by a precise pyrolytic procedure. One polymer that has produced a highly conductive organic material through thermal treatment is the diether-linked phthalonitrile polymer of U.S. Pat. No. 4,587,325. It has been determined that the ether linkages interrupt electronic delocalization. Hence a pyralyzed polymer without ether linkages would have a better electrical stability.

Polymer of dithioether-linked phthalonitrile

The United States of America as represented by the Secretary of the Navy

by Carolyn R. Price, legal representative