A system for positioning a plurality of heads traversing multiple disks in a disk drive system is disclosed herein. The positioning system includes a servo pattern recorded on at least one of the hard disks, the servo pattern having a sequence of servo locations successively recorded along concentric tracks on the disks. Burst zones are also recorded on the hard disks, each burst zone having multiple transitions recorded at staggered separate radial distances from the center of the disks. The positioning system contains means for computing servo burst signal magnitudes based on head position relative to the transitions in each burst zone, and means for calculating a head offset based on differences between the servo burst signal magnitudes and radial displacement of each head in each track. The positioning system transmits a correction signal based on calculated head position, and the output signal has a linear response for any head position on the disk.

Typical hard disk drive systems record information on circular disks, each disk having a multiplicity of tracks concentrically located thereon. Each disk drive normally contains a plurality of disks, each disk recording surface having one or more magnetic heads which transfer information to or from an external system. Each magnetic head is located on an arm, and all arms are aligned vertically and attached to a common head positioner assembly. The head positioner assembly is driven by a motor so that the arms and magnetic heads move uniformly across the surfaces of the vertically aligned disks. Head positioner assemblies are usually mounted to rotate the arms and magnetic heads along an arcuate path over the disks.
In normal operation, a host controller issues a track seek command. The controller electronics respond to the track seek command, determining the direction and magnitude of movement necessary to drive the heads from their current position to the destination position. Hard disks are generally divided into a plurality of concentric tracks, and data is read or written along each track. Further, position of the head on each disk, position of data on each disk, and the desired destination for arm movement is indicated by track indices. High performance disk drive units typically attempt to maximize the density at which tracks are written. In order to achieve higher densities, the positioner motor is energized, and the data read/write head counts the number of tracks it crosses until it reaches the destination. For example, if the head is at track 25, and the electronics require movement to track 256, the data head must read 231 track crossings. The drive motor accelerates to a maximum value for a calculated period of time and decelerates so that it attains zero velocity on reaching the destination.
Typically, the carriage on which the heads are mounted is incorporated in a servo system, which performs the necessary positioning functions. Three different types of servo systems exist: a dedicated servo system, which has servo information located on one of many disk surfaces, an embedded servo system, wherein each data surface is used to store the servo information, and the hybrid servo system, which uses a dedicated disk surface and a low sample rate embedded servo on each data surface to store servo information. The servo system senses the position of the heads by means of servo signals recorded in tracks on the disk surfaces. Embedded servo and hybrid servo system accuracy and data storage has been the object of developments within the disk drive field, as the accuracy at which the head can be made to follow the track centerline determines the density of the tracks located on a disk. The closer the head can be made to follow the track centerline, the closer together the tracks can be spaced on the disk, and storage efficiency increases.
A typical hard disk used in an embedded servo or hybrid servo system has a plurality of outwardly radiating "spokes" representing servo data. Each set of sectors between "spokes" represents zones where data is stored. Servo signals are typically arranged in frames, including an AGC field, sync mark, cylinder information, and servo burst information. Typically, four radially extending servo burst groups, designated A, B, C, and D, are used to assist in positioning the heads, as the signals generated by the heads in reading these four burst groups determine the radial position of the head.
Track centerline positions are determined by the system by comparing the servo burst signals received. That is, knowing the placement of servo burst data on the disk, the position of a head traversing a track can be calculated from the signals received.
Previous systems employing multiple servo burst groups used the following equation to determine position information: ##EQU1##
Alternately, various calculations using C and D in the denominator have been used, or constant value scale factors, to determine head position. The drawback of these systems was the requirement to calibrate for demodulator offsets, demodulator gains and head width variations, as well as the inherent nonlinearities associated with ratios of sums and differences. Demodulator gains include any imprecision in head positioning due to various gains applied to the sum and difference ratios used to determine position information. Gain rounding or inaccuracies adversely affected head positioning. With respect to demodulator offset, signals received must be demodulated to recover position information and convert it into the appropriate position signal for use by the position servo. This demodulation and conversion tends to create dc offsets which may be introduced into the position signal. With respect to head variations, strength of the signal generated in the servo transducer is a function of the actual gap width of the servo transducer, which affect the magnitudes of the servo burst signals (A, B, C, or D) received, introducing error into calculations which use these servo burst signals. Further, prior compensation schemes were inherently nonlinear, introducing unwanted position movement into the system.
Accordingly, it is an object of the current invention to provide an embedded or hybrid servo system having accurate head positioning capability.
It is another object of the current invention to compensate for demodulator offsets and head width variations in positioning data read/write heads. Signals received must be demodulated to recover position information and convert it into the appropriate position signal for use by the position servo. This demodulation and conversion tends to create dc offsets which may be introduced into the position signal. With respect to head variations, strength of the signal generated in the servo transducer is a function of the actual gap width of the servo transducer, which affects the magnitudes of the servo burst signals (A, B, C, or D) received. Thus, head variations must be minimized to avoid introducing error into calculations which use these servo burst signals.
It is still another object of the current invention to provide a linear head positioning system which does not cause unwanted position movement.

Method and apparatus for sensing position in a disk drive


The electric power system protection device according to the present invention includes a transformer including a primary winding and a secondary winding which are electrically isolated from each other. The primary winding is to be connected to a first electric path which is to be connected to an external power supply configured to supply AC power by use of a secondary battery, so as to receive the AC power from the external power supply. The secondary winding is to be connected to a second electric path to be connected to a power supply path from a commercial electric power system to an electric load.

There has been examined supplying electric power temporarily from electric vehicles incorporating secondary batteries, when electricity infrastructures become unavailable due to disaster or the like. In more details, an electric vehicle such as an electric drive vehicle (EV) and a plug-in hybrid drive vehicle (PHEV) is connected to an electric power wiring system (hereinafter referred to as "indoor wiring system") installed in a facility such as a residence, a factory, and an office, and then electric power is supplied from the secondary battery in the electric vehicle to the indoor wiring system. This indoor wiring system normally receives commercial electric power from the commercial electric power system.
For example, in supplying electric power from the secondary battery in the electric vehicle to the indoor wiring system such as HEMS (Home Energy Management System), electric power discharged from the secondary battery to the indoor wiring system is controlled by use of a charging stand provided between a charge and discharge device incorporated in the electric vehicle and the indoor wiring system. This charging stand includes an electric leakage detector on an electric path from the electric vehicle to the indoor wiring system. When electric leakage is detected, the charging stand breaks the electric path from the electric vehicle to the indoor wiring system (e.g., see document 1 [JP 2012-170258 A]).
Rules for interconnecting electric vehicles incorporating secondary batteries (external power supplies) and the commercial power supply system have not been determined yet. In consideration of protection of the electric power system, it is required that output current from the external power supply do not give direct effects on the commercial power supply system. Also in consideration of protection of the charge and discharge device incorporated in the electric vehicle, it is preferable that current outputted from the commercial power supply system do not give direct effects on the charge and discharge device in the electric vehicle.

Electric power system protection device, electric path switching device, and electric power supply system

Panasonic Intellectual Property Management Co., Ltd.


This invention concerns a system (1) for electronically aligning the polarisation of an antenna (2;2b) with the polarisation of a signal received therein or transmitted therefrom, said signal having two mutually orthogonal components, namely a vertical component (Cv) and a horizontal component (Co).

1. Field of the Invention
This invention relates to a system for electronically aligning the polarization of an antenna.
More particularly, this invention relates to a system for electronically aligning the polarization of a receive/transmit antenna to the polarization of a transmit/receive antenna communicating with the former.
As it is well known, the exploitations of computer networks and of the Internet network have been exponentially increasing in recent years. Many people utilize today the Internet network for exchanging data in many different fields of their business or for personal interests.
At present, the exploitation of large band data transmission services based upon use of satellite systems has become a real opportunity which is being extended from an experimental level to an operative condition thereby opening the way to relevant potential both economical and technical applications.
From a technological view point, the antenna represents an essential component. The interest in respect of ground terminals equipped with low cost antennas adapted to receive and to transmit signals from/to different satellites is, therefore, significantly increasing.
The more recent developments are related to technologies aimed at designing flat antennas adapted to operate in full duplex mode and provided both with receive functions and with transmit functions, in view of the fact that they are provided with a common antenna aperture.
A largely utilized antenna type in connection with which the technological research is being very rapidly developed is related to the flat array antenna systems, since they offer various advantages with respect to the reflector antennas commonly utilized today.
An antenna array is realized—as directly suggested by the same definition thereof—by an antenna assembly including a number of identical generally linearly or planar arranged antennas (namely arranged on a line or in a plane), having a common orientation. The individual component elements of these antenna arrays are generally fed with different amplitude and phase.
The main advantage of this technology consists in the possibility to obtain a readily configurable radiation diagram, by varying the amplitudes and the phases of the individual component antennas.
Furthermore, it is possible to design specific arrays aimed at achieving main lobes and their zeroes in desired positions. Among others, also programmable array antennas are known, capable to modify their own radiation diagram by modifying the feed of the individual component antennas of the array.
Antenna of this kind are particularly utilized in space applications where the material displacement of any single antenna or of an antenna array is often a very hard task to be carried out.
The antenna arrays also have among other advantages a compact outline and a more pleasant aesthetic effect. Their implementation in multiple layer construction also adds low manufacturing cost advantages and an easier integration possibility for the antenna electronics.
These characteristics make these antennas particularly attractive for mobile communications.
As it is well known to any person skilled in the art, if the polarization of the antenna of a transmitter and the polarization of the antenna of a receiver are not aligned (namely the horizontal and the vertical components are not aligned), the effectively useful distance for a connection is dramatically reduced. Therefore, it is necessary that the two concerned antennas: (i) always utilize the same polarization type; and (ii) their polarization directions be aligned.
In the technology as presently available, the alignment of the antenna polarization is completely obtained by mechanical azimuth and elevation rotations.
This orientation system, when an antenna array is utilized in the field of data transmission for mobile systems, generates various inaccuracies in the orientation of the antenna and consequently causes phase lags.
Due to this drawback, the presently available antenna arrays have strictly defined utilization limits, particularly for use in the field of DVB (Digital Video Broadcasting) transmissions.

System for electronically aligning the polarization of an antenna


An interlayer insulating film is formed. Then a first gate electrode and a second gate electrode are buried in the interlayer insulating film. Then, an anti-diffusion film is formed over the interlayer insulating film, over the first gate electrode, and over the second gate electrode. Then, a first semiconductor layer is formed over the anti-diffusion film which is present over the first gate electrode. Then, an insulating cover film is formed over the upper surface and on the lateral side of the first semiconductor layer and over the anti-diffusion film. Then, a semiconductor film is formed over the insulating cover film. Then, the semiconductor film is removed selectively to leave a portion positioned over the second gate electrode, thereby forming a second semiconductor layer.

The present invention concerns a semiconductor device having transistors in an interconnect layer and a method of manufacturing the semiconductor device.
Japanese Unexamined Patent Application Publication No. 2010-141230 describes that a semiconductor film is formed in an interconnect layer and transistors are formed by using the semiconductor film and the interconnect of the interconnect layer. In the transistor, the interconnect positioned below the semiconductor film is used as a gate electrode and anti-diffusion film between the interconnect layers is used as a gate insulating film.

Semiconductor device and method of manufacturing the semiconductor device


A foamed water discharging device includes a water feeding hole, a water discharging hole, a water passage, a ventilation passage, and a foamed water generator. The water passage has a cylindrical inner circumferential surface extending from the water feeding hole to the water discharging hole. The ventilation passage takes in external air on the upstream side of the water passage. The foamed water generator causes water containing the external air to undergo a collision on the downstream side of the water passage so as to convert the water into foamed water. The foamed water generator includes flow dividing ribs along the inner circumferential surface of the water passage, which protrude radially toward the center of the water passage. On a top portion of each flow dividing rib, at least a pair of inclined surfaces are formed to divide, rightward and leftward, water inflowing from a water guiding passage through the water feeding hole.

As conventionally known, in order to reduce the sound of water on a sink, a splash of water against the sink, and other related occurrences, foamed water discharging devices are attached to faucets, water plugs, and similar devices so as to prevent discharged water from spreading. The foamed water discharging devices mix air into part of water inflowing from the faucets, water plugs, or similar devices so as to change part of outflowing water into air bubbles. At the same time, the foamed water discharging devices cause the water to collide with something in the water passage through to a water discharging hole so as to change the water into foamed water.
Patent documents 1 and 2 each disclose a foamed water discharging device that includes: a pressure reducer that is disposed between a water feeding hole and a water discharging hole and that has a plurality of small holes to reduce the pressure of water flowing from the water feeding hole; a ventilation passage that has a plurality of air holes to cause air to be contained in the water outflowing through the pressure reducer; and a rectifier that is disposed on the downstream side of the ventilation passage and that causes the air-containing water to drop along the water passage so as to rectify the discharge direction of the air-containing water toward the water discharging hole.
In the foamed water discharging device disclosed in patent document 1, a stepless, tapered inclined surface is formed in the water passage on the downstream side of the pressure reducer (pressure reducing plate). A sprinkle of water is discharged through the plurality of small holes of the pressure reducing plate and caused to contact external air flowing into the water passage through the ventilation hole, resulting in air bubble water. Then, the air bubble water is dropped along the inclined surface of the water passage and changed into foamed water through the course to the rectifier, which has a lattice-shaped. Then, the foamed water is discharged.
The foamed water discharging device disclosed in patent document 2 includes a pressure reducer that forces out, with increased flowing speed, water inflowing from the water feeding hole toward the downstream side of the water passage. The pressure reducer includes a pressure reducing plate having a plurality of through holes. The water passage has an inclined surface that causes air bubbles to be contained in the water forced out through the pressure reducing plate and that guides the air bubble-containing water toward the center of the water passage. In the water passage, a rectifier is disposed that rectifies the direction of the water outflowing along the inclined surface toward the water discharging hole.

Foamed water discharging device and foamed water discharging unit


A chain drive mechanism, especially for a construction toy system, is assembled with individual U-shaped chain link elements. The chain link elements are notched at their open ends and provided with bearing portions at their closed ends. The notched open ends are arranged for snap-fit attachment over the bearing portions of adjacent links, enabling a flexible chain of any length to be easily assembled. Drive pins, preferably coaxial with the bearing portions, project outwardly from each side of the chain links and are engagable with grooves of spaced-apart drive wheels, collectively forming a sprocket assembly. The drive wheels can be individual gear elements otherwise used in a toy construction system for gear drive mechanisms. The base portions of the U-shaped link elements are grooved transversely for the snap-fit attachment of construction toy connector parts, allowing the chain elements to carry other components.

The present invention relates to a novel chain drive system for incorporation into a construction toy system, for use in driving movable parts located remotely from the drive input, for conveying elements from one location to another, etc. The drive system of the invention is most usefully incorporated in and combined with elements of the above mentioned Glickman patents.
The chain drive of the invention includes a novel chain link construction, in which each link, formed of injection molded structural plastic, is of a generally U-shaped configuration. The link element includes a pair of spaced-apart side elements, which are laterally notched adjacent their outer ends. The "base" portion of the U-shaped link has cylindrical bearing portions adapted for snap-in assembly with the notched side elements of an adjacent link. Once the snap-in assembly has been effected, the adjacent links are semi-permanently connected but can easily pivot about a transverse axis in the manner of a conventional link chain. The arrangement enables a drive chain to be assembled of any length suitable for the particular application. Disassembly is, of course, equally efficient. The chain structure is strong, extremely lightweight and, as will appear, highly versatile.
In a particularly preferred embodiment of the invention, each of the individual chain links, at its base, includes outwardly projecting drive pins at each side, axially aligned with the cylindrical bearings by which an adjacent link is connected. The spacing of adjacent sets of drive pins on successive links corresponds with the spacing between a predetermined number of teeth of a drive gear. In the preferred embodiment of the invention, a pair of such gears are mounted on a shaft in predetermined spaced-apart relation equal to the overall width of the chain links, as defined by the spaced-apart side elements. The respective gears are secured to a supporting shaft and provide a driving connection between the chain and the shaft. Opposed pairs of drive pins progressively seat in grooves, formed between successive teeth of the gears, providing a particularly advantageous form of driving connection between the chain and the gears.
In another preferred embodiment of the invention, the base portion of each chain link includes, in addition to the cylindrical bearing portions previously mentioned, a central coupling portion which is transversely grooved to accommodate snap-in assembly of a connector element of a type disclosed in the before mentioned U.S. patents. By assembling a connector element with selected links of a chain assembly, it is possible to provide additional driving functions, such as moving of parts on a conveyor structure, advancing vehicles up an incline for a roller coaster structure, etc.
For a more complete understanding of the above and other features and advantages of the invention, reference should be made to the following detailed description of a preferred embodiment of the invention and to the accompanying drawings.


A method of applying an electroplated layer to a surface of a polymeric composite material, the method includes the steps of: providing an uncured polymeric composite substrate; positioning a veil layer over a surface of the uncured polymeric composite substrate, the veil layer providing a conductive surface on the uncured polymeric composite substrate, the veil layer having a mat of metal coated fibres consolidated by an organic binder material; subjecting the uncured polymeric composite substrate to a curing cycle to form a cured polymeric composite material in which the veil layer is partially exposed; and applying an electroplated layer to the conductive surface of the cured polymeric composite material.

It is known to apply metallic coatings to the surface of composite materials for decorative purposes, for example decorative chrome coatings. Such coatings, typically electroplating directly onto the composite substrate, have low bond strength because they are applied by low cost processes.
There are alternative methods that can be used to provide metallic coatings to composite materials in which the coating has higher bond strength.
One such alternative is the use of vapour deposition techniques. While providing improved bond strength, these methods require high processing temperatures that can damage the composite substrate material.
A further such alternative the use of thermal spraying. Again, this technique can improve the coating bond strength but the abrasive grit blasting surface preparation can cause mechanical degradation of the composite material. These surface preparation requirements render thermal spraying techniques unusable on small or thin-walled components.

Method of applying an electroplated layer to a polymeric composite material


The present invention provides a generic method of preparing a metal matrix composite with a textured compound. A xe2x80x9croller-skatexe2x80x9d structure starting powder with a mixture of plate-like particles and smaller particles provides better flow compatibility, higher packing density, better densification and texture formation in preparing a metal matrix composite with a textured compound. In particular, the invention provides a method of preparing a textured superconducting composite wire with an improved critical current density.

The present invention relates to a method of preparing a metal matrix composite material with a textured compound. In particular, it relates to a method of preparing a textured superconducting composite wire.
Some important advanced materials have layered structures. For example, high temperature oxide superconductors and the superconducting intermetallic compound MgB2 are materials with a layered structure. The layered structure causes the anisotropy in physical properties, and texture formation is necessary to achieve superior performance. As the layered compounds are brittle, the layered compounds are often prepared as metal matrix composites to provide better mechanical properties.
One well-known method to prepare such composite materials is the xe2x80x9cpowder-in-tubexe2x80x9d method. This method has been used to prepare the low temperature superconducting compound Nb3Sn, the high temperature oxide superconductors, and the recently discovered intermetallic compound MgB2. According to the formation of the compound in the powder-in-tube method, the method is also classified into two categories: the in situ technique and the ex situ technique. For the in situ technique, the components in the elemental forms are used as the starting powder, and the compound is formed inside the tube after mechanical deformation of the composite wire. For the ex situ technique, a powder of the compound is used as the starting powder.
For the high temperature oxide superconductors, both metal precursor and oxide precursor were tested, and the best results so far were achieved with the Bi2223 and Bi2212 prepared by the oxide powder-in-tube method (See, for example, a summary by D. Larbalestier, xe2x80x9cThe road to conductors of high temperature superconductors: 10 years do make a differencexe2x80x9d, IEEE Trans. Appl. Supercond. 7(2) 1997, p90-97. Also refer to a review by H. Kitaguchi and H. Kumakura, xe2x80x9cAdvance in Bi-based high Tc Superconducting Tapes and Wiresxe2x80x9d, MRS BULLETIN, February 2001, p121-125). This is attributed to the weakly-bonded, double Bixe2x80x94O layer in the structures. The easy cleavage between the Bixe2x80x94O layers introduces texturing of the phase in the deformation process. Attempts to make superconducting wires for the rare earth 123 compounds have not been very successful in achieving a high critical current density for the powder-in-tube methods. For a recent effort in this area, refer to U.S. Pat. No. 6,202,287 by A. Otto which describes an attempt to make a bi-axially aligned 123 wire from a metallic precursor powder Although the melt-texture growth method has produced high critical current densities in bulk RBaCuO-123 superconductors, the very slow growth rate is not practical for the production of long length wires. Current efforts for the rare earth 123 compounds have been focused on the coated thin-film conductors (See a review by Finnemore et al., Physica C, 320, 1999, 1). Other related developments are discussed in the following references: S. Annavarapu et al., xe2x80x9cProgress Towards a Low-cost Coated Conductor Technologyxe2x80x9d, Physica C, 341-348, 2000, p2319-2322; L. R. Motowildlo et al., xe2x80x9cRecent Progress in High-temperature Superconductors at Intermagnetics General Corporationxe2x80x9d, Physica C, 335, 2000, p44-50; R. L. Meng et al., xe2x80x9cTape processing of HBCCO, BSCCO, and YBCO Thick films on Metallic Substrates with High Jc by the Spray/Compress Techniquexe2x80x9d, Physica C, 341-348, 2000, p2315-2318; M. Zhou et al., xe2x80x9cProperties of YBa2Cu3Ox films on textured Ag tapesxe2x80x9d, Physica C, 337, 2000, p101-105; S. P. Athur et al., xe2x80x9cMelt-processing of Yb123 tapesxe2x80x9d, Physica C, 341-348, 2000, p2421-2424.
Besides the powder-in-tube method, there are many other methods for the preparation of a metal matrix composite. Thin film methods have been used to prepare all types of superconducting materials mentioned above either through physical deposition or chemical deposition. Dip coating has been used to form a layer of compound on a metal substrate. The present invention is related to a bulk method using a powder as the starting material for a layered compound.
The challenges in preparing a composite with a textured compound by a powder method include:
(a) The flow compatibility of the metal and the powder. Poor compatibility will cause difficulty in the deformation process and the formation of sausage in the composite.
(b) Powder packing. A high powder density before sintering is preferred.
(c) Densification. The decrease in density of Bi2223 during heat treatment seems to be mainly caused by the growth of non-aligned oxide grains. International Application Publication WO 01/22436A1 by Li et al., entitled xe2x80x9cSimultaneous constraint and phase conversion processing of oxide superconductorsxe2x80x9d, and the references cited disclose various ways to apply pressure during various stages of heat treatment to deal with the desintering problem to certain degree of success.
(d) Texture formation. It is desirable to develop a high degree of texture in the layered compound. For certain superconducting materials with grain boundary weak link problems, good grain boundary connectivity is also required. In the prior art, texture in Bi2212 is formed through a melt-texture growth method.
Texture in Bi2223 depends on the rolling deformation and the easy cleavage of the 2212 phase. Therefore, a high critical current density is obtained only in the tape form for Bi2223. However, round wire or wires with a low aspect ratio are more desirable for many applications.
A processing method should provide solutions to all the challenges simultaneously in order to be commercially viable. Although superconductors, and especially superconducting wires, are used as examples in the following discussion, the present invention should be applicable to other metal matrix composites with textured compounds.
Therefore, an object of the present invention is to provide a method of preparing metal matrix composite with a textured compound, which has better flow compatibility, higher packing density, better densification and texture formation. As a result, improved performance of the compound will be obtained.
Another object of the present invention is to provide a method of preparing composite wires of layered superconducting materials with a better processing condition and improved superconducting properties such as a high critical current density.
Still another object of the present invention is to provide a method of preparing composite wires of layered superconducting materials with a low aspect ratio.
Still another object of the present invention is to provide a method of preparing bulk layered superconducting materials with improved superconducting properties.
According to the present invention, the starting powder for preparing a layered compound should comprise of
(a) A plate-like powder of the layered compound or an intermediate phase (metastable phase) for the layered compound which retains its shape at least at the initial sintering stage. This plate-like powder serves as the template for texture formation of the layered compound. The xe2x80x9cplate-like powderxe2x80x9d, as the term used in this specification, has a phase with a layered structure and the particles have a minimum basal plane dimension that is at least 1.62 times greater than the thickness dimension. The minimum basal plane dimension is the shortest line segment on the basal plane through its geometry center, which is the diameter of a circular shape, the side length of a square, or the length of the shorter side of a rectangular. Because of the natural variation in powder preparation, it should be understood that the majority ( greater than 50% by volume) of the particles should meet the requirement, and preferably 80%, and more preferably 90% of the particles should meet the requirement.
(b) The remaining powder with a particle size smaller than half the median minimum basal plane dimension of the plate-like powder. Preferably this powder has a near-sphere shape, or the dimensions in different directions are similar. This second powder may contain any phases which in combination with the first powder and under certain heat treatment will form the desired final compound. Suitable phases include, but are not limited to, pure metals, alloys, intermediate compounds, and the final compound.
In the prior art, two types of powder are used (FIG. 1A and FIG. 2A). The powder shown in FIG. 1A has predominantly equal-axial or near-sphere particles. This may correspond to a well-ground uniform fine powder. This type of powder has good deformation behavior, and therefore has relatively good flow compatibility with the metal sheath. However, the powder has a low packing density and a low tendency for texture formation (FIG. 1B). The powder shown in FIG. 2A has a predominantly plate shaped particles. This powder has poor flow compatibility with the metal sheath and a low packing density (FIG. 2B). Although it has a good tendency for texture formation during the deformation process, the low packing density makes sintering difficult, and the poor deformation behavior makes the wire prone to sausage formation. Although real powders have some deviations, the powder structures in FIGS. 1A-B and FIGS. 2A-B are representative of the predominant features of the powders in the prior art for the preparation of metal matrix composites.
A well-known technique to improve powder packing density in ceramics is illustrated in FIGS. 3A-B. The basic principle is to fill the voids of the previous close packed structure with spheres of suitable sizes. The process can be repeated to several levels of voids and a high packing density of around 95% theoretical density may be obtained. When this powder is used to make a metal matrix composite wire, good flow compatibility and a high packing density would be predicted. For a compound with an easy cleavage tendency such as Bi-based oxide superconductors, a high level of texture formation can be obtained in the rolling process to form a composite tape. However, desintering may occur during the sintering process partially due to the growth of certain misaligned grains. For a compound that will not cleave easily during the rolling process, texture formation is very limited.
The proposed powder structure according to the present invention is shown in FIGS. 4A-B. The raw powder is shown in FIG. 4A, and the structure shown in FIG. 4B may represent the powder at a later stage of deformation when the initially randomly distributed plate-like particles are aligned in the deformation process. Owing to the unique xe2x80x9croller-skatexe2x80x9d structure of the powder, a good deformation behavior and a high packing density are both obtained. A high packing density means that the relative density is at least 70%, more preferably 80%, and most preferably 90%. The plate-like particles, acting like the xe2x80x9cboardxe2x80x9d of a xe2x80x9croller-skatexe2x80x9d, can slide easily on the smaller particles acting as xe2x80x9crollersxe2x80x9d. The roller particles are preferably near-sphere in shape. When the roller particles are much smaller in size (say less than 10% of the size of plate-like particles), the shape factor becomes less important. The xe2x80x9croller-skatexe2x80x9d powder structure artificially mimics the structures of the Bi2212 and Bi2223 phase where the easy cleavage between the weakly bonded Bixe2x80x94O layers provides the self-alignment property during deformation. As the attraction between the xe2x80x9cboardxe2x80x9d particles and the xe2x80x9crollerxe2x80x9d particles is even weaker in the proposed xe2x80x9croller-skatexe2x80x9d powder structure, it would be expected that texture formation will occur at a less shear strain level than the value for texture formation in the Bi-based compounds. During sintering, the plate-like particles act as templates for textured growth of the final compound. Moreover, the formation of textured grains between the plate-like particles provides an opportunity to structurally adjust possible mismatches between the plate-like particles. For oxide superconducting materials sensitive to grain boundary mismatch, this provides an extra mechanism for strongly coupled grain boundaries and hence an improved critical current density. Therefore, the present invention provides a generic method for the preparation of a metal matrix composite with a textured compound.
The volume fractions of the two powders can be estimated from a simplified model. Suppose the plate-like particle has a thickness t1 and the second powder has a packing density xcfx812 and a particle size of d2. Imagine that we can cut the powder into vertical slices and within each slice we can rearrange the plate-like particles so that the plate-like particle can form complete layers with the second powder between them. If the number of second powder particles in between is n, then the volume fraction f1 of the plate-like powder is:
f1=t1/(t1+nd2xcfx812)=1/(1nd2xcfx812/t1)xe2x80x83xe2x80x83Equation (1)
The choice of the volume fraction of the plate-like powder is a complex issue. A suitable value should provide an adequate amount of texture templates without any significant decrease in the powder flowability. Equation (1) can serve as a general guideline for the volume fraction of the plate-like powder. Assume a typical value for xcfx812 as 74% and the particle size of the second powder equals the thickness of the first powder, we can calculate some typical values as shown in Table 1. Similar calculations can be performed for other conditions, such as the values in Table 2. An n value of about 2 or greater can be used. A larger n value will be used for a relatively smaller particle size of the second powder. For example, the f1 value of 93% in Table 2 may be difficult since bridging would occur for the first powder at this high volume fraction. The upper limit will be around the possible packing density of the plate-like powder alone. The volume fraction of the first powder would be in the range of 10 to 80% for most powders.
The choices of the particle size and shape of the powders are important considerations. For the plate-like powder, the dimension ratio between basal plane and thickness is preferably greater than 3. The particle size of the plate-like powder (measured on the average dimension of the basal plane) should be in the range of microns to tens of microns. The particle size of the second powder is preferably less than 20% of the particle size of the first powder, or in the range of microns and even smaller size. The particle size of the second powder can be controlled by grinding.
The components for the second powder can be prepared separately and then mixed together, or they can be prepared in a single powder batch. The second powder may contain particles of different size as shown in FIGS. 3A-B to obtain a high packing density.
In another aspect of the invention, the second powder further comprises at least one deformable phase so that it will facilitate the deformation of the whole powder. By deformable it is meant that the phase will either deform plastically without destruction or the particles break up into smaller pieces under the deformation process.
In still another aspect of the invention, the second powder further comprises a component or components that form a transient liquid phase during the sintering process. Such liquid forming phases include low melting components, eutectic liquid phase, and specially added liquid forming metal salts. This liquid phase will help the sintering process, and more importantly provide a mechanism for grain boundary adjustment so that low energy special grain boundaries will be formed. This will be of particular importance to many oxide superconductors.
In a preferred embodiment, the second powder comprises at least one metallic or alloy component so that a mixed mode of in situ and ex situ mechanisms is provided. This will take advantage of the merits of both mechanisms. For example, for oxide superconductors, the first powder is a plate-like oxide superconductor, and the second powder comprises the metallic powders of appropriate composition. The two powders are mixed to form a starting powder. Then the starting powder is used to make a composite wire according to the deformation process of the xe2x80x9cpowder-in-tubexe2x80x9d process to develop texture in the plate-like particles. The metallic powder is converted into oxides during the sintering process. As the plate-like particles will act as templates for the formation of the intended final oxide superconductor, highly textured superconductor grains will be formed with a high critical current density. The amount of the metallic powder in the second powder can also be adjusted as needed.
Similarly, for MgB2, the first powder is plate-like MgB2 particles, and the second powder contains Mg and B particles. B can even exist in an alloy or compound and the extra element in the alloy or compound can diffuse into the sheath material or simply exist as second phases.
In another preferred embodiment, the process to make a composite is the powder-in-tube method. A composite wire is prepared by filling the starting powder into a metal tube and reducing the cross section of the tube through mechanical deformation such as swaging, rolling, extrusion, or drawing, and for a multifilamentary wire, assembling the previously formed bundles and further deforming the assembly into a multifilamentary wire. The plate-like powder is textured during the deformation process. After sintering, improved properties are obtained due to the template texture formation.
A composite can also be prepared by other known composite processing methods, such as dip coating, tape casting, spray coating, liquid metal infiltration, and multi-layer layout.
In still another aspect of the invention, the powder is pre-textured before the major reduction process of the composite. The pre-texture operation can be accomplished by any mechanical means or magnetic alignment due to the anisotropy of magnetic properties of the plate-like powder. When a pre-textured powder is used, high reduction rolling is not necessary to achieve a high degree of texture. Therefore, instead of preparing composites in the tape form, composite wires with low aspect ratios can be prepared by more uniform deformation methods such as drawing and extrusion. The pre-textured powder also allows for the use of a variety of composite preparation methods without deformation. The pre-texture powder precursor can also be used to prepare highly textured bulk compound with improved physical properties.
By xe2x80x9ctexturexe2x80x9d as the term is used herein, it is meant that the layered compound grains have been aligned with the basal plane to a significant degree. If the phases of the second powder are different from the first powder, the texture of the plate-like powder can be easily quantified using the lotgering factor, or f-factor from the X-ray diffraction pattern of the material with a value of zero for random orientation and a value of 1 for perfect alignment. In preferred embodiments, the f-factor has a value of at least 0.6, more preferably 0.8, and most preferably 0.9. If the phase of the first powder is also included in the second powder, the texture information of the first powder may be difficult to determine due to contribution of the second powder to the X-ray diffraction pattern. If the orientation of the second powder is random, the texture information of the first powder can be obtained by certain calculation.
Otherwise, direct observation of the microstructure can provide information about the alignment. In preferred embodiments, at least 60% of the plate-like particles are within 10 degrees of the intended alignment, and this number should reach more preferably 80% and most preferably 90%.
In a preferred embodiment, the metal matrix composite is in the form of a wire. By xe2x80x9cwirexe2x80x9d as the term is used herein, it is meant an elongated article with its length dimension significantly (at least 2 times and normally orders of magnitude) larger than the dimensions of the cross section. It is equivalent to a tape, a ribbon, a rod, or the like, used in the literature.
In preferred embodiments, the layered compound is a layered superconducting material. Intermetallic compound MgB2, rare earth RBaCuO-123 oxide superconductor (where R is an element or mixture of elements of Y, La, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu), Bi-based (Bi,Pb)SrCaCuO-2223 and (Bi,Pb) SrCaCuO-2212 oxide superconductors, TI-based oxide superconductors, and Hg-based oxide superconductors, are all layered superconducting materials.
In a preferred embodiment for preparing layered superconductors, the layered superconducting material is pre-textured for the preparation of the superconducting material. This allows for the use of a variety of composite preparation methods with more uniform deformation process and even no deformation process at all. For example, low aspect ratio superconducting wires can be prepared from textured feeding bar using the drawing process. FIGS. 5A-C show some of the low aspect ratio configurations.
An advantage of the powder structure of the present invention for the preparation of a layered oxide superconducting composite is that inexpensive metal substrate materials can be used instead of silver-based materials. A metallic material can be coated with an oxygen diffusion barrier layer such as a metal oxide and used as the substrate for the superconducting materials. Such metallic materials include carbon steel, stainless steel, superalloys, nickel-based materials, copper-based materials, and titanium-based materials. Since the texture formation mechanism is independent of the substrate material, more choice of substrate materials and barrier layer preparation methods are available, which in turn expands the temperature ranges and related processing methods. In addition, the superconducting layer can be made much thicker than what can be achieved in the coated superconductor method.

Method of preparing metal matrix composite with textured compound


Process for treating synthesis gas to recover a purified essentially sulfur-free hydrogen-rich stream. The novel sequence of operations employed comprises initially removing from the feed gas, such as from a synthesis gas derived from partial oxidation of coal or oil, the bulk of contained H.sub.2 S and a substantial part of the contained COS, by physical absorption in a suitable solvent. The gas from the initial absorption is then subjected to water-gas shift reaction over a sulfur-resistant shift catalyst under conditions such that in addition to the conversion of CO to CO.sub.2 most of the contained COS hydrolyzed to H.sub.2 S. The gaseous shift product is then subjected to a second treatment with suitable solvent to remove by physical absorption essentially all of the remaining sulfur, which is then present as H.sub.2 S. The thus desulfurized gas mixture is then sent to a CO.sub.2 absorber, from which a H.sub.2 -rich gas effluent is withdrawn. The H.sub.2 S bearing solvent from the second treatment is used in the initial absorbtion. H.sub.2 S is stripped from the initial rich absorption bottoms liquid to recover a Claus gas effluent of high H.sub.2 S content, while the stripped liquid bottoms are recycled for further use in the process.

1. Field of the Invention
This invention relates to the production of purified hydrogen-rich gas from a synthesis gas mixture containing CO and acid gas contaminants including CO.sub.2, H.sub.2 S and COS.
2. Description of the Prior Art
Numerous methods for removal of acid gas from gas mixtures containing the same are well known in the art and in commercial practice. Included among the known processes for acid gas removal from gaseous streams are those employing physical absorption of CO.sub.2 and/or H.sub.2 S as distinguished from other processes involving chemical reaction. The physical processes are particularly preferred when the feed gas to be treated is available at high pressure and contains relatively large quantities of acid gas constituents and selective separation is desired. Numerous and diverse organic solvents have been suggested or utilized for the desired absorption. Included among the solvents used in known commercial process are methanol, employed in the Rectisol process (U.S. Pat. No. 2,863,527); N-methyl-2-pyrrolidone, used in the Purisol process (U.S. Pat. No. 3,505,784); propylene carbonate, used in the Fluor Solvent process (U.S. Pat. No. 2,926,751); and dimethyl ethers of polyethylene glycol, used in the Selexol process (U.S. Pat. Nos. 2,649,166; 3,362,133). Other proposed solvents include: N-substituted morpholine (U.S. Pat. No. 3,773,896); hexafluoroisopropyl alcohol (U.S. Pat. No. 3,339,342); dimethyl formamide or dimethyl sulfoxide (U.S. Pat. No. 3,676,356); among other solvents suggested as physical absorbents for acid gas are: tri-n-butyl phosphate, methyl cyanoacetate, glutanitrile, trimethylene cyanohydrin, N-formyl morpholine.
In addition to the many different types of absorption solvents heretofore used or proposed for use in desulfurization and CO.sub.2 removal from gas mixtures, a variety of differences in operation techniques and process conditions appear in the patented art and published technical literature. The more widely adopted systems, however, in general, follow an operational sequence that may be characterized as conventional hereinbelow described.
In these conventional processes for desulfurization and removal of CO.sub.2 from gas mixtures, such as those obtained by partial oxidation of heavy oils or by gasification of coal, the presence of COS in the feed poses difficulties in desulfurization when physical solvent absorption systems are employed. In such conventional processes the feed gas is charged to an absorption column wherein it is contacted with the selected physical solvent for absorption of H.sub.2 S and COS. The thus desulfurized gas is subjected to a catalytic shift reaction with steam wherein the CO is converted to CO.sub.2 and hydrogen is obtained. The resulting gaseous effluent from the shift converter is treated with a selected suitable solvent for absorption of CO.sub.2 and the resulting gaseous effluent is sent to a methanation section for hydrogenation of residual CO and CO.sub.2, obtaining a hydrogen-rich gas product. The fat liquor from the desulfurizing absorber is stripped of contained H.sub.2 S and COS, providing a product gas from which sulfur values may be recovered in a Claus plant and the lean solvent is recycled for reuse in further treatment of feed gas. The fat solvent from the CO.sub.2 absorber is flashed to remove a portion of the CO.sub.2 therefrom, then stripped of residual CO.sub.2 with air or inert gas and the thus stripped liquid is recycled for reuse in the CO.sub.2 absorber column.
The utility requirements for the operation of such conventional processes are comparatively costly. In certain of these conventional processes solvent flows required for COS removal in desulfurization results in a dilute Claus gas (typically containing about 11-12 mole % H.sub.2 S) which is too dilute for processing in conventional Claus plants for recovery of sulfur values. Accordingly, special expensive Claus plants need to be used, which require high purity oxygen instead of air for burning a part of the H.sub.2 S to SO.sub.2 or a sulfur product recycle oxidation. In addition, such processes require special expensive Claus tail gas units.
Other of these conventional processes for desulfurization of feed gas mixtures, such as those employing methanol as solvent for the sulfur gas, have been designed to produce a Claus gas of sufficiently high H.sub.2 S content that can be charged to a conventional Claus gas system. These systems, however, need to make use of an extra column to concentrate the H.sub.2 S. Other conventional processes for desulfurization of gas mixtures obtain a Claus feed containing from about 20% to over 50% H.sub.2 S. The solvents generally employed in such processes, such as, for example, methanol, N-methyl pyrrolidone or dialkyl ethers of polyethylene glycol, are such that the solubility of H.sub.2 S therein is much greater than that of CO.sub.2, while the solubility of COS is intermediate of these. When COS is absent the desulfurization solvent flow rate is set for essentially complete H.sub.2 S removal and only a small fraction of the CO.sub.2 is coabsorbed, so that the desired concentration Claus feed is obtained. When COS is present, however, a substantially higher solvent flow rate is required to obtain complete absorption and desulfurization, with consequent increase in equipment costs and utility requirements. The coabsorption of CO.sub.2 is also increased by the higher solvent flow rate and deep flashing of the rich solvent must be utilized to obtain a satisfactory Claus feed containing a required minimum of about 20% H.sub.2 S. In addition to the foregoing drawbacks, the increased compression requirements for the flash gas further adds substantially higher capital investment in equipment and higher power costs.
The hereinabove described difficulties and other drawbacks of these earlier known processes for desulfurization of gas mixtures are largely avoided in accordance with the novel process of the present invention and the economics of the operation are favorably improved, as will hereinafter appear.

Process for producing hydrogen from synthesis gas containing COS


A new cultivar of Spathiphyllum plant named ‘Jetson’ that is characterized by dark green leaves, a white spathe, a white spadix and a bushy habit with dense foliage.

The present invention relates to a new and distinct cultivar of Spathiphyllum plant botanically known as Spathiphyllum and hereinafter referred to by the cultivar name 'Jetson'.
'Jetson' was discovered in the Spring of 2003 as a naturally occurring branch mutation of a plant of Spathiphyllum 'Jetty' (U.S. Plant Pat. No. 9,957). 'Jetson' was discovered in a cultivated area of Nootdorp, The Netherlands.
Asexual reproduction by tissue culture of the new cultivar 'Jetson' was first performed in November 2003 in Nootdorp, The Netherlands. Since that time, under careful observation, the unique characteristics of the new cultivar have been uniform, stable and reproduced true to type in successive generations of asexual reproduction.


Disclosed is a process for the production and purification of dialkyl naphthalenedicarboxylate compounds wherein a crude naphthalenediacarboxylic acid is esterified with an alkanol such as methanol to produce a crude esterification product comprising dialkyl naphthalenedicarboxylate, starting materials and other compounds and the crude esterification product is purified by flash distillation to remove impurities which can cause fouling of conventional distillation equipment. A particularly useful diester is dimethyl 2,6-naphthalenedicarboxylate.

2,6-NDC is conveniently formed by the esterification of crude 2,6-naphthalenedicarboxylic acid (2,6-NDA) with methanol. Crude 2,6-NDA typically is contaminated with a variety of by-products such as trimellitic acid (TMA), brominated naphthalene compounds, and 6-formyl-2-naphtbalenecarboxylic acid (FNA). The heavy metals such as cobalt and manganese used to catalyze the oxidation of 2,6-dimethylnaphthalene to 2,6-NDA form insoluble complexes, particularly with the TMA, and typically are included in the crude 2,6-NDA in excess of 1,000 ppm. The insoluble heavy metal complexes form deposits and foul heat exchangers in the esterification process, leading to frequent process interruptions for cleaning and maintenance. It is advantageous to remove the heavy metal contaminants at an early stage in the process to avoid problems in operations.
U.S. Pat. Nos. 5,254,719 and 5,095,135 disclose the use of sulfuric acid as a catalyst to esterify 2,6-NDA to 2,6-NDC. Sulfuric acid is effective at a relatively low temperature, e.g., about 130.degree. C., and it reacts with the heavy metal impurities to form soluble sulfate salts. Disadvantages of sulfuric acid-catalyzed esterifications include corrosion of the reactor and the yield loss of methanol to dimethyl ether. Disposal of waste sulfates is another problem with the use of sulfuric acid catalysts. In addition, the reaction usually is carried out well under the melting point of 2,6-NDC (about 200.degree. C.) to minimize or avoid the above mentioned problems with corrosion and dimethyl ether formation. Thus, the reaction is run in methanol solvent, resulting in a larger vessel for a given residence time relative to a reaction in which the excess methanol is substantially removed in the vapor phase.
U.S. Pat. Nos. 4,003,948 and 5,350,874 and Japanese Unexamined Patent Application (Kokai) 7-233123 disclose processes wherein the esterification is operated at higher temperatures with or without a metallic esterification catalyst. This method has the advantage of reduced dimethyl ether formation and corrosion. Disadvantages include generally higher pressure with no provision to reduce fouling by residual oxidation catalyst metals on heat exchanger or reactor surfaces. Without a provision to recycle incompletely esterified 2,6-NDA to the reactor, it is desirable to run the reaction at a high conversion. In a single backmixed reactor, high conversions are achieved at the expense of increased residence time and larger, more expensive reactors. Methods to narrow the residence time distribution, such as multiple reactors in series or devices to approach a tubular reactor like that disclosed in U.S. Pat. No. 5,350,874, are more expensive and add additional complexity to parts of the process subject to fouling. In the process disclosed in Japanese Unexamined Patent Application (Kokai) 7-233123, the 2,6-NDC is distilled following the reactor and methanol stripper, but the 2,6-NDC distillation is done under vacuum, and there is no provision to recycle partially converted 2,6-NDA. To avoid fouling in the distillation column base heater, it is necessary to dilute the residual oxidation catalyst metals with valuable 2,6-NDC, monomethyl ester of 2,6-naphthalenedicarboxylic acid (2,6-MHN), and 2,6-NDA, thus reducing the yield of 2,6-NDC. It is also necessary to operate the reactor at a high conversion to 2,6-NDC as there is no provision for concentration of the 2,6-NDC in the distillation.
U.S. Pat. No. 3,227,743 addresses some of these problems as they apply to the esterification of terephthalic acid (TPA) with methanol to produce dimethyl terephthalate (DMT) by operating a bubble column reactor under conditions such that the DMT product is removed as a vapor with excess methanol and the water of reaction. The lower vapor pressures of 2,6-DNC and the impurities present in crude 2,6-NDC have until now prevented a direct application to 2,6-NDC. There remains a need in the art for an efficient process for the manufacture of 2,6-NDC that minimizes fouling, operates at high rates, and presents a distilled product free of residual oxidation catalyst metals and other high boilers to a final purification process.

Process for the preparation of dialkyl esters of naphthalenedicarboxylic acids


Disclosed is a method of down-regulating the expression of a gene in an animal, wherein a pharmalogical formulation comprising an oligonucleotide complementary to the gene is orally administered to an animal. The oligonucleotide administered has non-phosphodiester internucleotide linkages and includes at least one 2'-substituted ribonucleotide, the oligonucleotide inhibiting the expression of a product of the gene, thereby down-regulating the expression of the gene.

The present invention relates to the control of gene expression. More particularly, this invention relates to the use of synthetic oligonucleotides to down-regulate the expression of a gene in an animal.
The potential for the development of an antisense oligonucleotide therapeutic approach was first suggested in three articles published in 1977 and 1978. Paterson et al. (Proc. Natl. Acad. Sci. (USA) (1977) 74:4370-4374) discloses that cell-free translation of mRNA can be inhibited by the binding of an oligonucleotide complementary to the mRNA. Zamecnik et al. (Proc. Natl. Acad. Sci. (USA) (1978) 75:280-284 and 285-288) discloses that a 13 mer synthetic oligonucleotide that is complementary to a part of the Rous sarcoma virus (RSV) genome inhibits RSV replication in infected chicken fibroblasts and inhibits RSV-mediated transformation of primary chick fibroblasts into malignant sarcoma cells.
These early indications that synthetic oligonucleotides can be used to inhibit virus propagation and neoplasia have been followed by the use of synthetic oligonucleotides to inhibit a wide variety of viruses, such as HIV (see, e.g., U.S. Pat. No. 4,806,463); influenza (see, e.g., Leiter et al. (1990) (Proc. Natl. Acad. Sci. (USA) 87:3430-3434); vesicular stomatitis virus (see, e.g., Agris et al. (1986) Biochem. 25:6268-6275); herpes simplex (see, e.g., Gao et al. (1990) Antimicrob. Agents Chem. 34:808-812); SV40 (see, e.g., Birg et al. (1990) (Nucleic Acids Res. 18:2901-2908); and human papilloma virus (see, e.g., Storey et al. (1991) (Nucleic Acids Res. 19:4109-4114). The use of synthetic oligonucleotides and their analogs as anti-viral agents has recently been extensively reviewed by Agrawal (Trends in Biotech. (1992) 10:152-158).
In addition, synthetic oligonucleotides have been used to inhibit a variety of non-viral pathogens, as well as to selectively inhibit the expression of certain cellular genes. Thus, the utility of synthetic oligonucleotides as agents to inhibit virus propagation, propagation of non-viral, pathogens and selective expression of cellular genes has been well established.
Improved oligonucleotides have more recently been developed that have greater efficacy in inhibiting such viruses, pathogens and selective gene expression. Some of these oligonucleotides having modifications in their internucleotide linkages have been shown to be more effective than their unmodified counterparts. For example, Agrawal et al. (Proc. Natl. Acad. Sci. (USA) (1988) 85:7079-7083) teaches that oligonucleotide phosphorothioates and certain oligonucleotide phosphoramidates are more effective at inhibiting HIV-1 than conventional phosphodiester-linked oligodeoxynucleotides. Agrawal et al. (Proc. Natl. Acad. Sci. (USA) (1989) 86:7790-7794) discloses the advantage of oligonucleotide phosphorothioates in inhibiting HIV-1 in early and chronically infected cells.
In addition, chimeric oligonucleotides having more than one type of internucleotide linkage within the oligonucleotide have been developed. Pederson et al. (U.S. Pat. Nos. 5,149,797 and 5,220,007 discloses chimeric oligonucleotides having an oligonucleotide phosphodiester or oligonucleotide phosphorothioate core sequence flanked by nucleotide methylphosphonates or phosphoramidates. Furdon et al. (Nucleic Acids Res. (1989) 17:9193-9204) discloses chimeric oligonucleotides having regions of oligonucleotide phosphodiesters in addition to either oligonucleotide phosphorothioate or methylphosphonate regions. Quartin et al. (Nucleic Acids Res. (1989) 17:7523-7562) discloses chimeric oligonucleotides having regions of oligonucleotide phosphodiesters and oligonucleotide methylphosphonates. Inoue et al. (FEBS Lett. (1987) 215:237-250) discloses chimeric oligonucleotides having regions of deoxyribonucleotides and 2'-O-methyl-ribonucleotides.
Many of these modified oligonucleotides have contributed to improving the potential efficacy of the antisense oligonucleotide therapeutic approach. However, certain deficiencies remain in the known oligonucleotides, and these deficiencies can limit the effectiveness of such oligonucleotides as therapeutic agents. For example, Wickstrom (J. Biochem. Biophys. Meth. (1986) 13:97-102) teaches that oligonucleotide phosphodiesters are susceptible to nuclease-mediated degradation, thereby limiting their bioavailability in vivo. Agrawal et al. (Proc. Natl. Acad. Sci. (USA) (1990) 87:1401-1405) teaches that oligonucleotide phosphoramidates or methylphosphonates when hybridized to RNA do not activate RNase H, the activation of which can be important to the function of antisense oligonucleotides. Thus, a need for methods of controlling gene expression exists which uses oligonucleotides with improved therapeutic characteristics.
Several reports have been published on the development of phosphorothioate-linked oligonucleotides as potential anti-AIDS therapeutic agents. Although extensive studies on chemical and molecular mechanisms of oligonucleotides have demonstrated the potential value of this novel therapeutic strategy, little is known about the pharmacokinetics and metabolism of these compounds in vivo.
Recently, several preliminary studies on this topic have been published. Agrawal et al. (Proc. Natl. Acad. Sci. (USA) (1991) 88:7595-7599) describes the intravenously and intraperitoneally administration to mice of a 20-mer phosphorothioate linked-oligonucleotide. In this study, approximately 30% of the administered dose was excreted in the urine over the first 24 hours with accumulation preferentially in the liver and kidney. Plasma half-lives ranged from about 1 hour t.sub.1/2.alpha.) and 40 hours (t.sub.1/2.beta.), respectively. Similar results have been reported in subsequent studies (Iversen (1991) Anti-Cancer Drug Design 6:531-538; Iverson (1994) Antisense Res. Devel. 4:43-52; and Sands (1994) Mol. Pharm. 45:932-943). However, stability problems may exist when oligonucleotides are administered intravenously and intraperitoneally.
Thus, there remains a need to develop more effective therapeutic methods of down-regulating the expression of genes which can be easily manipulated to fit the animal and condition to be treated, and the gene to be targeted. Preferably, these methods should be simple, painless, and precise in effecting the target gene.

Method of down-regulating gene expression


An adaptive low pass filtering process with a filter delay DA is conducted in parallel with reference low pass filtering process with a filter delay DR which is greater than DA. The error is measured between a delayed version of the adaptive process output and the reference process output. Filter parameters of the adaptive process are controlled to minimize the error.

In real-time sampled-signal processing such as digital filtering, each output sample depends typically on a number of input samples and, in the case of recursive processing such as infinite impulse response (IIR) filtering, additionally on past output samples. In most applications there will be a correspondence in time between input samples and output samples. For example, an event in the input signal that is preserved by the process would be considered to be contemporaneous with the corresponding event in the output signal. In many cases it is desirable that the process has access to input samples both in the past and in the future. However, since a causal system cannot in reality access future samples, the process has to wait until the last required input sample has arrived before it can produce its output. This waiting period is known as the latency or pipeline delay of the process.
The latency of a process is therefore defined as the number of sample periods of delay that elapses between an event at the input to the process and the corresponding event at the output. In general, this delay need not be an integer; for example, the delay of a filter whose output is the average of input signals across a sample-period delay will be 0.5 sample periods. Latency is related to but not in general identical to group delay; however, for a symmetric or linear-phase filter such as the example just given, latency and group delay are identical. In the description that follows, latency is usually expressed as a whole number and may also be thought of as the number of "future" samples that would have to be made available to the filter in order for there to be no delay between input and output events.
This invention relates to processes or filters which are linear (at least instantaneously). By linear is meant that a linear transformation applied to the original input of the process or filter will result in a new output which is related by the same linear transformation to the original output. So, for example, processes involving rank ordering, quantisation or envelope detection are not linear processes.
Let us illustrate the property of latency in the case of a linear sampled-signal filter.
Consider a sampled input signal f(t) where t takes integer values. Suppose we wish to perform a filtering operation on this signal where the output depends on surrounding input and output samples:g(t)=G(f(t−n),f(t−n−1), . . . ,f(t+m),g(t−k),g(t−k+1), . . . ,g(t−1)where m, n and k are positive integers. In the case of a symmetric finite impulse response (FIR) filter, m=n and k=0 and there is a direct, unambiguous correspondence between g(t) and f(t). In the more general case, we assume that an input event at a sample labelled t would be manifest at the output at the sample labelled t.
The output of this filter at any moment thus depends on m+n+1 input samples, which are considered to extend from n sample periods in the "past" to m sample periods in the "future", and on k "past" output samples.
This filtering operation may be represented diagrammatically as shown in FIG. 1. In this example, n=4, m=3 and k=5.
Because the output of the filter at time t depends on input samples considered to be up to m sample periods later than time t, the output cannot actually be calculated until time t+m, as represented in FIG. 2, where the samples are aligned with a time axis. We say in this case that the filter has a latency, or pipeline delay, of m=3 sample periods.
When designing a filter, there are two conflicting requirements regarding latency. In many applications, it is desirable to have access to a large number of "future" input samples. For example, if the object is to smooth or low-pass filter the signal, then many input samples are required, and if constant group delay is required, the filter also needs to be symmetric, so about half the samples need to be "future" samples, giving rise to a high latency. However, in real-time processing it is also desirable to minimize the latency so that the filter responds quickly to events at the input.
It is the object of certain aspects of this invention to provide a method or apparatus for real-time signal processing with low latency that retains some or all of the performance advantages available from processes with higher latency.


This is a mold repairing method for removing a resin material deposited on a mold, of which the surface is a porous film with a plurality of recesses that have been created through anodization. The mold repairing method includes the steps of: (I) removing the resin material that is exposed on the surface of the mold over the plurality of recesses without performing atmospheric pressure plasma processing; and (II) removing at least partially the resin material that is still left inside the plurality of recesses by the atmospheric pressure plasma processing, after the step (I) has been performed, thereby recovering the original function of the mold.

Recently, various kinds of optical elements with a very small structure, of which the feature size is as small as the wavelength of visible light (that falls within the range of about 380 nm to about 780 nm) and which is sometimes called a "sub-wavelength structure (SWS)", have been developed. If an uneven pattern, of which the feature size is equal to or smaller than the wavelength of incoming light, is formed on the surface of a substrate, then reflection of the light from the surface can be reduced. The size of those recesses and projections that form such an uneven pattern may be set to fall within the range of 10 nm to less than 500 nm, for example.
Among other things, an antireflection technology based on the principle of a moth-eye structure has attracted a lot of attention these days. With the moth-eye structure, the refractive index can be changed virtually continuously in those recesses' or projections' depth (or height) direction. That is to say, the surface with the moth-eye structure has no interfaces which have substantive refractive index differences in the light traveling direction, and therefore, can reduce the reflection of light effectively enough.
The moth-eye structure is advantageous because the structure not only performs an antireflection function with small incident angle dependence over a wide wavelength range but also is applicable to a lot of materials and contributes to forming an uneven pattern on the substrate directly. That is why by adopting the moth-eye structure, a high-performance antireflection film can be provided at a lower cost.
The moth-eye structure may be formed using an anodized porous alumina layer (porous oxide film) which is obtained by anodizing an aluminum base (see Patent Document No. 1, for example). Hereinafter, such an anodized porous alumina layer obtained by anodizing an aluminum base will be described briefly.
If an aluminum base is immersed in an acidic electrolytic solution of sulfuric acid, oxalic acid, phosphoric acid, or any other appropriate acid, and if a voltage is applied thereto using the aluminum base as an anode, oxidation and dissolution will advance concurrently on the surface of the base. As a result, an oxide film with a huge number of nanopores (i.e., a porous aluminum layer) is formed over the surface of the base.
Those nanopores will be formed in the shape of circular cylinders perpendicularly to the oxide film. In addition, if the anodization process is carried out under a predetermined condition, those nanopores will get self-organized and arranged in a regular pattern. Consequently, by performing such an anodization process on aluminum, a very small structure with various regular patterns can be formed relatively easily and cost-effectively.
The applicant of the present invention discloses, in Patent Document No. 1, a method of forming an antireflection film (antireflective surface) using a stamper which has an anodized porous alumina film over its surface. Patent Document No. 1 also discloses a technique for forming an antireflection film using an alumina layer, of which the very small recesses have a stepped side surface.
If the porous alumina film is used, a mold for forming a moth-eye structure on the surface (which will be referred to herein as a "moth-eye mold") can be made easily. In particular, as disclosed in Patent Document 1, if the surface of the anodized aluminum film is used as a mold as it is, the manufacturing cost can be cut down significantly, which is beneficial.
An antireflection film can be made just by pressing the moth-eye mold against a photocurable resin that has been applied onto a transparent film, for example. More specifically, the uneven surface of the moth-eye mold is pressed against the photocurable resin in a vacuum. Then, the photocurable resin is irradiated with an ultraviolet ray with the moth-eye mold still pressed against it. After that, when cured, the resin is released from the moth-eye mold. Such a method of transferring the surface shape of a mold onto a resin while curing the resin with an ultraviolet ray is called a "UV imprinting technique".

Die repairing method and method for manufacturing functional film using same


An improved beehive for shedding moisture and protecting bees includes a condensation promoting surface that provides for controlled condensation of water vapor to form liquid water and transport of the condensed liquid water out of the beehive.

I. The Field of the Invention
The invention is in the field of beehives and beekeeping and includes apparatus and methods for reducing moisture within a beehive or other containers for living organisms.
II. The Related Technology
Honeybees are social bees of the genus Apis. They are commonly kept in a semi-domesticated form for production of honey and pollination of crops. Domesticated honeybee colonies are typically housed in an enclosed structure commonly called a "beehive."
As illustrated in FIG. 1, a conventional beehive 100 is typically composed of three main parts: (1) a "bottom board" 102 which forms the floor of the beehive; (2) the "hive body" 104 comprised of one or more bottomless boxes stacked on the bottom board and that provide a hive interior in which bees can live; and (3) the "cover" 106 which acts as a lid and roof to the system.
The environment inside of a beehive is typically warm and humid from the respiration of the honeybee colony and the evaporation of nectar in the production of honey. Beehives are typically vented to prevent excessive buildup of heat and humidity during warmer seasons. A passive updraft of ventilation air enters a vent near the bottom of the hive, passes upward through the interior of the hive body, and exits through one or more vents near the top of the beehive (e.g., through or near the cover).
During cold seasons, particularly in temperate climates, bees typically become dormant and form a cluster 110 to share and conserve heat. To maintain adequate warmth within the hive and prevent excessive loss of heat through the cover, a porous insulation barrier (not shown) can be placed near the top of the hive body above the cluster 110 and below the cover 106. The insulation barrier retains within the hive sufficient heat generated by the bees to prevent freezing and death. In addition, the porous insulation barrier can permit warm humid air 112 in the hive to rise and exit the hive through one or more vents (not shown). However, when the dew point of humid air 112 is equal to or greater than the temperature of the underside of cover 106 or walls of hive body 104, water vapor can condense, forming condensed water droplets 114, which can drip onto the bee cluster 110, causing sickness or death. Condensed water on the inner walls of hive body 104 can also cause mold formation.
In some cases a sponge-like body having a high affinity for moisture can be used as the porous insulation barrier. Examples include sawdust and diapers. Gel substances contained in diapers are capable of absorbing and holding large amounts of water, such as condensed water 114 dripping from the inner surface of cover 106. However, once the water absorbing substance is saturated it is no longer able to absorb more condensed water 114, and the risk of such water 114 dripping on the bee cluster 110 greatly increases. Water absorbing substances can be replaced periodically to maintain their water absorbing ability and prevent dripping onto the cluster.
Alternatively, a ventilation fan can be provided, which can be periodically activated to further vent the hive and prevent excess buildup of humidity and condensation. As long as a proper balance of insulation and ventilation is maintained, the beehive can stay sufficiently warm and dry through cold periods to prevent mold growth and/or dripping of water onto the bee cluster.


A switch assembly (10) for installation on a dynamoelectric machine (M). An electrical overload switch (12) is interconnected with the dynamoelectric machine and electrical conduits (C) are routed thereto for resetting the dynamoelectric machine after it is shut down due to an overload condition. A conduit box (14) has opposed sidewalls (16, 18) and endwalls (20, 22), and an open top and bottom. A bracket (30) on which the switch is mounted is sized to fit in the box for a switch element (32) of the switch to be positioned adjacent an opening (34) in one wall of the box. Dimples (44a, 44b) are formed in the wall against which the bracket is installed. The dimples extend inwardly into the interior of the box and act as stops for the bracket for properly positioning the bracket and switch within the box. A plurality of knockouts (K1-K6) are formed in the sidewalls for providing an opening through which electrical conduits are routed to the switch when a knockout is removed. Mounting flanges (24, 26) are formed on opposite sides of the box for mounting the box to a cover (60) of the dynamoelectric machine. The cover has a top (62) sized to fit over the interior of the box. The top has a peripheral depending sidewall (64) covering an upper portion of respective sidewalls and endwalls of the box. Dimples (66a-66c) are formed in a section of the cover sidewall and extend inwardly. The box has corresponding dimples (70a70c) formed therein into which the dimples in the cover sidewall fit for mounting the cover onto the box.

This invention relates to switch assemblies for use with large dynamoelectric machines including electric motors and generators having a control switch such as an overload reset switch mounted on the motor shell or endshield of the machine, and more particularly, to an improved, lower cost assembly.
It is not uncommon to mount larger dynamoelectric machines such as higher fractional horsepower or multi-horsepower motors or generators to a floor or other fixture at a using site. For this purpose, a bracket is attached to the motor with the bracket then being mounted to the floor or fixture. It is also not uncommon for the motor or generator to have an associated switch mounted to its outer shell or endshield. The switch is typically an overload protector type switch which interrupts power flow to the machine when an overload condition occurs. The switch is then either manually reset when the overload condition has been corrected; or, in some systems, the switch can be automatically reset. Electrical conduit for conveying power to the machine is routed from a central, power distribution network to a conduit box or enclosure in which the switch is also mounted. When electrically connected, the switch is interposed in the circuit path for powering the machine.
Previously, the switch was attached to a mounting bracket which was then riveted or welded to inside walls of the conduit box. This installation thus required a secondary manufacturing step which added cost to the machine assembly and its installation. Further, were the switch to fail, replacement of the switch required the replacement of the conduit box with the associated disconnection and reconnection of the conduits. This imposed an additional cost to the maintenance of the system in which the machine is used. Finally, there were a number of different sized conduit boxes which were used with different machines. By standardizing the size of a switch mounting bracket, it would be possible to reduce the number of boxes required and therefore reduce inventory costs.

Switch assembly and mounting bracket therefor


A waveguide for projecting a longitudinal acoustic wave of wavelength .lambda. from an ultrasound energy source toward a target area. The waveguide has at least one tubular channel. The channel has inwardly tapered, conical inlet and outlet ports separated by a venturi. The inlet port taper defines a sharply rimmed entry orifice around the inlet port. A separation distance equal to one wavelength .lambda. is maintained between the source and the waveguide's inlet port. The waveguide shears off a cross-section of the wave emitted by the energy source and ejects it at accelerated velocity toward the target area. The channel has a length L and the venturi has a diameter D, such that the waveguide has an emitted beam angle equal to 2 (tan.sup.-1 (D/L)). Preferably, a plurality of tubular channels are aligned concentrically around and longitudinally parallel to the one tubular channel, each channel having a selected length and a selected diameter. The channels are preferably circular in cross-section, with their outlet ports located in an inwardly scalloped front face of the waveguide.

Ultrasound detectors are used to detect vehicles, pedestrians, or the like moving through regions such as selected portions of vehicle traffic intersections. By monitoring such movement traffic engineers can gauge changing traffic flow patterns and take appropriate action, such as adjusting the operation of traffic signal lights.
Ultrasonic energy beams projected through air by such prior art devices typically diverge considerably from the ultrasound energy source. Waveguides employed in such prior art devices commonly utilize reflective techniques and tuned assemblies to compensate for such divergence and thereby improve detection accuracy. The present invention, by contrast, shears off a cross-section of the energy pattern emitted by the ultrasound energy source and ejects it at accelerated velocity toward the target area. This enables the invention to minimize divergence by controlling the beam angle of the emitted ultrasonic energy beam.


Polycyclic aromatic group-pendant polysilanes of the following general formula are described. EQU [(R.sup.1 R.sup.2 Si).sub.k (R.sup.3 R.sup.4 Si).sub.m ].sub.n. wherein R.sup.1, R.sup.2, R.sup.3, and R.sup.4 are, respectively, a hydrogen atom or a monovalent hydrocarbon group provided that at least one of R.sup.3 and R.sup.4 is a monovalent hydrocarbon group having a polycyclic aromatic group or a biphenyl group. When the polysilane is doped with an oxidative dopant, the polymer is rendered electrically conductive and has thus wide utility in various fields of photoconductive and electrically conductive materials without involving degradation of the polysilane.

1. Field of the Invention
This invention relates to novel polycyclic aromatic group-pendant polysilanes which have utility as photoconductive and electrically conductive materials and are particularly useful in the fields of electrodes for batteries, solar cells, boxes for electromagnetic shields and the like, and also to conductive polymers obtained by doping such polysilanes.
2. Description of the Prior Art
In recent years, it has been found that doping of polyacetylene with electron acceptors or electron donors results in a charge transfer forming reaction, thereby developing high electric conductivity based on the electron conduction. Attention has now been paid to conductive organic polymer compounds such as polyacetylene, polyphenylene, polypyrrole, polyaniline and polythiophene for use as materials capable of forming highly conductive films.
However, these organic polymer compounds are not molten or fused and are poor in shaping properties. Accordingly, the following problems are involved. Where these polymers are formed into films according to a vapor phase polymerization process or an electrolytic polymerization process, limitation is inevitably placed on the shape of the resultant film, which depends on the shape of a reactor container or an electrode. In addition, when doped with electron acceptors or electron donors, the polymers suffer considerable degradation, thus presenting problems with practical applications.
On the other hand, known polysilanes are predominantly made of those polysilanes which have, as substituents, an alkyl group typical of which is a methyl group, and a phenyl group (R. West et al., J. Am. Chem. Soc. 103, 7352 (1981)).
Also, there have been prepared polysilanes which have hydrogen or reactive carbon-carbon double bonds as a substituent or which have halogenated alkyl groups. This enables one to crosslink the polysilanes, with increasing expectations of their applications (R. West et al., J. Organomet. Chem., 300, 327 (1986)).
Very recently, there have been proposed applications, to resist materials, of polysilanes into which silyl groups are introduced (Japanese Laid-open Patent Application No. 63 -12636 or U.S. Pat. No. 4,727,120) and polysiloxanes introduced with phenolic substituents (Japanese Laid-open Patent Application No. 63-113021 or U.S. Pat. Nos. 4,822,716, 5,017,453 and 5,198,520).
Polysilanes contain silicon atoms, so that they are more metallic in nature and exhibit greater non-electron-localizing properties than those compounds made of carbon atoms. In addition, polysilanes are highly resistant to heat, are flexible and have good thin film-forming properties, thus being very interesting polymers. However, few polysilanes have been known as having high conductivity, with the exception of West el al's polysilastyrenes which are doped with fluorine compounds such as SbF.sub.5, AsF.sub.5 and the like, thereby obtaining highly conductive polymer materials (R. West et al, J. Am. Chem. Soc., 103, 7352 (1981)). However, there is a demand for conductive polysilanes which exhibit high electric conductivity and which are obtained conveniently from the standpoint of industry.

Polycyclic aromatic group - pendant polysilanes and conductive polymers derived therefrom


A on-line method for detecting erosion or plugging for manifolded feed nozzle systems which carry two-phase liquid/gas flow by determining a liquid flow parameter related to liquid flow. The method can determine whether the erosion is at the liquid nozzle or the gas restriction orifice. The amount of erosion or plugging can be quantified.

The present invention describes an on-stream method for detecting erosion or partial plugging of manifolded nozzles or restriction orifices (RO) in a two phase (gas/liquid) feed system. The method does not require direct mechanical contact between the sensor and liquid material.
Two phase nozzles are important for a variety of applications particularly for the injection of atomized feed in chemical or petroleum processing operations. In many such processes, operability or selectivity improvements result when an atomized hydrocarbon liquid is sprayed in a controlled and measured manner into the reaction zone, particularly when a process catalyst is involved. One example is the process of fluidized catalytic cracking (FCC) of higher boiling petroleum fractions. Typically, a high degree of atomization is achieved by mixing the liquid feed with a gas and injecting the mixture into the process from a feed nozzle designed to produce finely dispersed drops. In catalytic cracking, steam is typically used as the atomizing gas, but any process compatible gas may be used.
The need to control and measure the distribution of the atomized liquid sprayed into a process vessel is normally satisfied by using multiple services or nozzles. Maintaining the proper mixture of liquid to steam for atomization, and ensuring that each nozzle carries a specified liquid or mass flow, enables potential unit operating advantages. One common operating mode is to maintain equal liquid flow in each nozzle. Appropriate atomization is maintained by ensuring proper flow rates to nozzles with carefully designed geometries that are assumed invariant with operations. Most installations which have multiple feed nozzles usually include block valve or restriction orifices on the liquid and gas lines to an individual nozzle; but these controls do not uniquely determine the liquid flow. When nozzles are fed from a common manifold, there is no assurance that the liquid flow through each nozzle is optimized since only the net liquid flow to the total manifold can be readily measured. In contrast, the gas flow to a nozzle is usually determined by a restriction orifice on the gas line which ensures relatively definitive gas distribution to the individual nozzles.
Measuring mass flow of a liquid is not new. There are a variety of flow meters that have been used to measure mass flow. Some of them are mechanical in nature utilizing the force of a moving liquid to turn a wheel or deflect a needle. Such flow meters can only measure mass flow in single phase conditions and are usually restricted to non-fouling liquids. Those flow meters available for the single phase flow common to the petroleum and petrochemical industry tend to be quite costly. The very high temperatures that are maintained to reduce flow viscosity impose yet other complications. Furthermore, the service liquids readily foul and clog the mechanical components of such flow meters.
There are a variety of flow meters known as "vortex flow meters" that utilize vortex wakes proceedings from obstacles placed in the flow to measure the velocity of the flow from the frequency of vortex shedding. Such flow meters are again limited to single phase flow. Again, they require placement of an obstacle in the flow, and hence are again prone to fouling. The temperature range of most systems is narrow due to fundamental restrictions on the sonic transducers required to pick up the sound generated by the obstacle.
There are a variety of acoustic flow meters that utilize ultrasonics to measure flow. A class of such flow meters utilizes an ultrasonic transducer/receiver attached to the pipe containing the moving fluid, and an ultrasonic receiver/transducer attached to the same pipe upstream and/or downstream of each other. The high operating temperature of many petroleum and petrochemical processes, as well as geometrical constraints on the attachment of the acoustic device, make these flow meters expensive and difficult to apply in many petroleum and petrochemical applications. The temperatures often exceed the operating limits of many single phase flow meters.
Measurement of the liquid fraction of a gas/liquid mixture flowing through two phase nozzles is difficult. Usual devices for flow measurement are sensitive only to the velocity of the flow or its pressure and not to mass flow. Hence, such devices are incapable of measuring liquid flow without separate and equally complex measurements of the density of the mixture. Devices that are capable of measuring single phase liquid flow are expensive and are often intrusive since they require the insertion of an orifice or barrier in the flow which can be easily fouled by the liquid portion of the mixture. Since in most petroleum and petrochemical applications, the two phase mixture is maintained at an elevated temperature to achieve a sufficiently low viscosity for flow, there is a temperature limitation on flow measurement devices as well.
Thus most petroleum and petrochemical installations do not meter flows to each feed nozzle because suitable flow meters and control valves are expensive due to the severity of process conditions and pipe geometry limitations. The development of specialized flow meters to meet such stringent conditions would require significant expense and undesired complexity. Moreover, existing techniques do not permit on-line identification of partial plugging or erosion at individual feed nozzles. Current practices do utilize pressure sensors at nozzles to identify conditions that can be attributed to significant plugging.
Although petroleum and petrochemical processing units may demonstrate improved operation with specified liquid distribution and feed atomization from manifolded feed nozzles, only the net liquid flow to the manifold is usually measured or controlled. However, the probability of flow imbalance, erosion, or plugging among feed nozzles is large due to the complex nature of two phase fluid exiting the nozzle. Uncertainties in liquid distribution are compounded by the possibility that the liquid portion of the fluid could be vaporized. The existence of such flow imbalance is usually inferred only by anomalous process conditions or changes in process output yields over an extended period of time. Furthermore, the feed nozzle throat can partially plug or erode leading to significant flow maldistributions and/or poor feed atomization which can remain undetermined until the unit is shut down for maintenance. Similar plugging or eroding can also occur at the steam restriction orifice. There is thus a need for a technique that can measure and monitor erosion or partial plugging at an individual nozzle. Early identification of nozzle throat erosion or plugging enables operational changes to the process. Such changes include mechanical repairs (where possible) and flow redistribution via adjustments in the oil block valve.

On-stream method for detecting erosion or plugging for manifolded feed nozzle systems