Radical initiated reactions of phenylenediamines with alkylated aromatic amines produce an antioxidant mixture containing cross reaction products of the phenylenediamines and alkylated aromatic amines which are useful, for example, as antioxidants, stabilizers, and antiozonants for lubricants, electronic chemicals, rubbers, urethanes and other polymer resins, crop protection, pharmaceuticals, dyes and toners.

Lubricants, such as those used in a variety of machinery, are susceptible to oxidative deterioration during storage, transportation, and usage, particularly when such lubricants are exposed to high temperatures and iron catalytic environments, which greatly promote their oxidation. This oxidation, if not controlled, contributes to the formation of corrosive acidic products, sludge, varnishes, resins, and other oil-insoluble products and may lead to a loss of physical and tribological properties of the lubricants. Oxidation of aviation lubricants, such as synthetic polyol esters, is particularly undesirable, given the potential consequences of in-flight engine failure. It is therefore a common practice to include antioxidant additives in lubricants to prevent, at least to some extent, oxidation, so as to extend the useful life of the lubricants.
Alkylated diphenylamines are widely known in the art as antioxidants. Commercial applications include lubricants, rubber, plastics, polyurethanes, hydraulic fluids, greases and fuels.
The use of 1,4-benzenediamines is also known, as exemplified in U.S. Pat. Nos. 2,718,501, 2,883,362, 3,211,793, 3,304,285, and 5,711,767, U.S. Publication Nos. 2006/0128574, 2006/0189824, and 2007/0006855, GB1296592, and GB0835826 and JP59020392, the disclosures of which US patents and applications are incorporated herein by reference. 1,4-benzenediamines have more commonly been employed as motor fuel stabilizers and antiozonants and antioxidants for rubber.
U.S. Pat. No. 2,451,642 discloses meta-phenylenediamine, N1,N3-dimethyl-meta-phenylenediamine, and lauryl-meta-phenylenediamine as useful antioxidants for lubricating oil compositions in environments where iron-catalyzed oxidation reaction can take place. N,N′-dimethyl-ortho-phenylenediamine, N,N′-dicyclohexyl-para-phenylenediamine, and various di- and tetra-n-alkyl-para-phenylenediamines are similarly disclosed.
U.S. Pat. No. 2,718,501 discloses a stabilizer system consisting of an aromatic amine with at least two aromatic rings, including N,N′-diphenyl-para-phenylenediamine, and an organic aliphatic sulfur compound, which is said to be suitable for stabilizing mineral hydrocarbon lubricating oils, synthetic hydrocarbon oils, and polyalkylene glycol oils.
U.S. Pat. No. 2,857,424 discloses the preparation of oxalic acid salts of fuel stabilizing N,N′-dialkyl-para-phenylenediamines as a way of rendering the additives less toxic.
U.S. Pat. No. 3,402,201 discloses N,N′-dicyclooctyl-p-phenylenediamine as a stabilizer for organic materials, particularly rubber, and exemplifies its use as a gasoline inhibitor. The similar use of N,N′-dicyclooctyl-o- and m-phenylenediamines is contemplated.
U.S. Pat. Nos. 5,207,939 and 5,312,461 disclose certain Mannich base reaction products of mono- or dialkyl-phenylenediamines, an aldehyde or ketone, and a hindered phenol, which can be used in an antioxidant amount in lubricating oils, greases, and fuel compositions.
U.S. Publication No. 2006/0128574 discloses the use of physical mixtures of secondary diarylamines in combination with N,N′-dialkyl-para-phenylenediamines, and optionally hindered phenolics, as stabilizers for lubricants and fuels, but is silent regarding improvements in performance that may be achieved by reaction products thereof.
U.S. Publication No. 2006/0189824 discloses various N-alkyl-N-(dialkylhydroxyphenyl)alkyl-N′-phenyl-para-phenylene diamines, methods for their preparation by Mannich reactions of dialkylphenols with N-phenyl-para-phenylenediamines, and their use as antioxidants.
U.S. Publication No. 2007/0006855 discloses the use of alkylated para-phenylenediamines as soot dispersants in passenger car and heavy-duty diesel engines equipped with exhaust gas recirculation systems. An extremely broad scope of polyalkylated para-phenylenediamines is disclosed for this specific application alone.
Japan Patent No. 59-020,392 discloses a lubricant composition comprising N, N′-di-sec-butyl-para-phenylenediamine for pressure forming of oil tanks. The lubricant composition also contains hindered phenolic antioxidant.
Oberster, A. E. et al., 45 CAN. J. CHEM. 195-201 (1967), prepared 39 novel phenylenediamines as part of a program to find antiozonants for rubber that are not sensitizers or dermatotoxic. In some compounds the N′-phenylenediamine nitrogen was variously fused into a pyrrolidine, piperidine, hexamethyleneimine (homopiperidine), morpholine, or 2,6-dimethylmorpholine ring.
Makogon, A. N. et al., 12 KHEMICHESKAYA PROMYSHLENNOST, SERIYA: METODY ANALIZA I KONTROLYA KACHESTVA PRODUKTSII V KHIMICHESKOI PROMYSHLENNOSTI 18-21 (1980), describe the characterization of N, N′-dialkyl-para-phenylenediamines reaction products obtained by the catalytic alkylation of 4-aminodiphenylamine with C7-C9 alcohols.
While phenylenediamines are known to act effectively as antioxidants, the presence of these compounds in amounts conventionally used to provide antioxidancy displayed aggressiveness toward fluoroelastomeric engine seal materials. These adverse effects are particularly apparent with phenylenediamine compounds having higher nitrogen contents (compounds having relatively small hydrocarbyl substituents).
U.S. Pat. Nos. 3,509,214 and 3,573,206 describe the use of inorganic oxidants, such as potassium permanganate, lead dioxide, manganese dioxide, and hydrogen peroxide to prepare an oligomeric mixture between a phenyl naphthylamine and an alkylated diphenylamine. However potassium permanganate or manganese dioxide form very fine precipitates that readily clog filter apparatus. Lead dioxide is to be avoided for obvious environmental reasons.
U.S. Pat. Nos. 3,901,815 and 4,064,059 disclose compositions of alkylated phenylnaphthyl-amines and alkylated diarylamines as antioxidants for pentaerythritol and trimethylolpropane ester aviation turbine lubricants.
U.S. Pat. No. 4,110,234 describes the stabilization of a poly alpha olefin oil with an antioxidant comprising an alkylated phenyl naphthylamine, a sulfur compound, and a trace amount of a metal, such as copper or nickel. U.S. Pat. No. 4,122,021 describes the stabilization of any of a poly alpha olefin, a highly saturated mineral oil, or and ester oil with an antioxidant comprising an alkylated phenyl naphthylamine and a sulfoxide. U.S. Pat. No. 4,770,802 claims phenyl napthylamines that are substituted with a branched chain of 12 to 15 carbons.
U.S. Pat. No. 5,160,647 teaches the Mannich dimer product 4,4′-methylenebis[N-(4-tert-octylphenyl)-1-naphthylamine] as an antioxidant for aircraft turbine lubricants.
U.S. Pat. No. 6,426,324 describes the use of an organic peroxide radical source to prepare an oligomeric mixture between two diarylamines, e.g., a phenyl naphthylamine and an alkylated diphenylamine. The mole ratio of diphenylamine to phenyl naphthylamine is between 1:1 and 10:1. The patent does not contemplate the use of an organic peroxide radical source to prepare an oligomeric mixture between a phenyl naphthylamine and a substituted phenylenediamine.
U.S. Pat. No. 7,307,049 discloses reaction products of alkylated phenyl naphthylamines and formaldehyde as antioxidants for synthetic polyol ester lubricating oils.
EP 606,863 A3 discloses alkylated phenyl naphthylamines as antioxidants for oxyalkylene glycols and their mono- and dialkyl ethers.
EP 2,055,763 A1 describes the use of an alkylated phenyl naphthylamine in combination with two different alkylated diphenylamines as antioxidants, at least one of which has a number average molecular weight of from 321 to 700. The arylamine antioxidants in question are all well known commercially available materials which do not contain additional arylamine substituents or condensates.
The foregoing US disclosures are incorporated by reference.

Cross products and co-oligomers of phenylenediamines and aromatic amines as antioxidants for lubricants


Disclosed is an image forming apparatus including, at least, an image data storage unit that stores image data; an inclination amount detection unit that detects a first inclination amount of a portion of the image data spanning from one end to the other end relative to a main scanning direction; an inclination amount storage unit that stores, when a gradient of the image data changes at a point in the main scanning direction, a second inclination amount of a portion of the image data spanning from the one end to the point or from the other end to the point; a correction amount calculation unit that calculates correction amounts associated with the main scanning direction by switching, at the point, whether the first inclination amount is increased or decreased by the second inclination amount; and an image correction unit that corrects an image based on the correction amounts.

1. Field of the Invention
The present invention relates to an electrophotographic image forming apparatus, and especially to an image forming apparatus having a function to correct an image.
2. Description of the Related Art
In an electrophtographic image forming apparatus, in order to expose a photoreceptor, a Light-Emitting Diode (LED) may be used as a light source. LEDs can be arranged to correspond to pixels. In this case, the LEDs are disposed as an LED array, which are arranged in a main scanning direction. An image forming apparatus, which is capable of outputting a full-color image, includes a tandem type image forming apparatus having LED arrays. Here, the LED arrays are for corresponding colors of photoreceptors for developing a cyan (C) toner image, a magenta (M) toner image, a yellow (Y) toner image, and a black (K) toner image, respectively. The tandem type image forming apparatus forms a full-color image by sequentially forming and superposing images in the corresponding colors on an intermediate transfer belt or on a paper sheet. If toner image forming positions for the corresponding colors are shifted, an image having a color deviation is eventually formed.
To address this problem, in many cases, a tandem type color image forming apparatus includes a color deviation correcting function (e.g., Patent Document 1 (Japanese Unexamined Patent Publication No. 2010-140019)). FIG. 1 is a diagram illustrating an example of a color deviation correcting pattern. The color deviation correcting pattern includes lines in the corresponding colors of C, M, Y, and K, which are in parallel with the main scanning direction; and lines, which are slanted with respect to the main scanning direction by a constant angle. The image forming apparatus includes optical sensors 21 and 22 which read the color deviation correcting pattern. Here, the optical sensors 21 and 22 are separated from each other in the main scanning direction. For example, a registration deviation of the color of C in a sub-scanning direction is corrected based on a distance from a line K 11 to a line C 11, while setting the line K 11 as a reference line. A registration deviation of the color of M in the sub-scanning direction is corrected based on a distance to a line M 11, and a registration deviation of the color of Y in the sub-scanning direction is corrected based on a distance to a line Y 11. Similarly, a registration deviation of the color of C in the main scanning direction is corrected based on a distance from a line K 12 to a line C 12, while setting the line K 12 as a reference line. A registration deviation of the color of M in the main scanning direction is corrected based on a distance to a line M 12, and a registration deviation of the color of Y in the main scanning direction is corrected based on a distance to a line Y 12.
Additionally, the image forming apparatus may perform skew correction for reducing a color deviation, which is caused by tilting of the LED arrays in the main scanning direction. In the skew correction, the left and right color sensors read the correcting pattern, and a skew amount KC_Skew of the color of C with respect to the color of K is calculated, for example. The image forming apparatus performs the skew correction by shifting a timing for reading out pixel data corresponding to the skew amount KC_Skew, for a position of the pixel in the main scanning direction (by shifting the pixel, which is read out from a line memory, in the sub-scanning direction).
In the skew correction according to the related art, an amount of the color deviation is detected by the optical sensors, which are disposed at the corresponding two positions in left and right. Thus, linear skew may be corrected. However, bending skew may not be corrected. To correct the bending skew (which is skew such that a gradient is changed in the middle in the main scanning direction), another optical sensor may be added to a position other than the two positions in left and right. However, in this case, the cost may be increased.
There are many causes of the color deviation. The skew of the LED array is not necessarily the linear skew. For the case of the bending skew, if only the two optical sensors are disposed at the corresponding two positions, an amount of the bending may not be detected at a position other than the two positions. Accordingly, in the related art, the skew correction is applied while assuming that it is linearly inclined.

Image forming apparatus and image correction method that calculate correction amounts associated with a main scanning direction


The present invention discloses a wind power generation tower. The wind power generation tower, according to various embodiments of the present invention, comprises: a wind collection unit and an energy conversion unit, wherein wind power generation can be implemented by accelerating wind speed even for low speed wind and simultaneously increasing the utilization efficiency of the wind which rotates blades, thereby improving overall power generation efficiency.

In general, a wind power generation system refers to a system that generates electric power by converting wind energy into mechanical energy using a technology of converting wind power into a rotation force to generate electric power, and driving a generator.
Wind power generation systems are generally classified into a horizontal axis wind power generation type and a vertical axis wind power generation type. The horizontal axis wind power generation is highly efficient but has a problem in that it is greatly influenced by a wind direction. The vertical wind power generation is not greatly influenced by a wind direction but has a problem in that its efficiency is not high as compared to horizontal axis wind power generation. Accordingly, most major companies in the wind power generation field have focused on the horizontal axis wind power generation, and have conducted considerable studies on a method for enhancing an efficiency of the vertical axis wind power generation. However, they have failed to find a proper method for enhancing the efficiency of the vertical axis wind power generation up to the present. Meanwhile, since the present invention is related to the vertical axis wind power generation, the following description will be made with reference to the vertical axis wind power generation.
The vertical axis wind power generation is technically advantageous in that wind entering into all directions may be used but has a problem in that it is difficult to perform wind power generation efficiently because wind entering from the air is generally irregular in direction and strength. Accordingly, in order to solve this problem, various methods for efficiently concentrating wind directions have been attempted. For example, it has been proposed to additionally install a wind collection tube structure having a guide wall around the vertical axis wind turbine such that wind may flow in a uniform direction and a wind speed may be increased.
Korean Patent Laid-Open Publication No. 2009-0035884 (Wind-Acceleration Type Wind Power Generator) discloses a technology in which a drag-type wind turbine is installed inside and a wind collection tube structure configured to be capable of making a wind direction uniform and increasing a wind speed is installed around the drag-type wind turbine so that the efficiency of a vertical axis wind turbine can be enhanced.
In addition, Japanese Patent Laid-Open Publication No. 2010-531594 (Wind Turbine Having Vertical Axis) discloses a technology in which a drag-type vertical axis wind turbine is provided inside a wind tower, and a wind collection tube structure configured to be capable of making a wind direction uniform and increasing a wind speed is installed around the drag-type vertical axis wind turbine.
However, since the wind collection tube disclosed in each of the above-described publications are designed such that wind guided into the wind collection tube is directly contacted with and rotates drag-type wind blades, it is difficult to maintain wind power generation continuously because the movement of the of the drag-type blades is changed depending on a change of the wind. In addition, the wind passing through the guide wall is adapted to directly come in contact with the drag-type blades, thereby generating considerable resistance. Therefore, such a configuration is advantageous in initial starting of the drag-type blades but has a problem in that when the wind speed is high, the wind rather acts as resistance, which hinders efficient wind power generation.
Accordingly, the inventors have developed a wind power generation tower provided with a vertical axis wind turbine configured to solve the technical problems as described above.

Wind power generation tower provided with gyromill type wind turbine


A protective case which includes two mating case components and a liner extending between a peripheral area for mating engagement to ensure a relatively sealed relationship when the case components are closed. A latch face is a single elongated element on the front and has two spaced interlocking components to cooperate with hooks in the opposite case component.

Field of the Invention
This invention relates in general to a protective case. In particular, it is concerned with a case which permits for effective shock absorbance to components contained in the case.
Many different carrying cases are known for containing and protecting components. The different cases have different characteristics, each with different limitations. These cases do not have an effective closure and latching characteristics operable in a useful and easy manner, and do not necessarily provide for effectively sealing the container in an easy manner.
The present invention is directed to providing a suitable protective case for securely and sealingly carrying components. The case also permits for relatively straightforward and positive latching with components which are easier to use than latches in known cases. The case seeks to overcome the limitations of known cases.


A syringe pump has a motor rotating a leadscrew to drive a plunger head actuator along it. The head actuator engages the plunger of a syringe and moves the plunger along the syringe barrel to dispense medication. An optical encoder mounted on the leadscrew is rotated by the motor to produce a pulse output. A control unit times the interval between the pulses and compares these timings with a stored value representative of a predetermined multiple of the minimum time. If the head actuator is obstructed, the speed of rotation of the motor is slowed and the time interval between pulses rises. When this exceeds the stored value, the control unit stops the drive to the head actuator and generates an alarm.

This invention relates to syringe pumps.
Syringe pumps are used to supply medication to a patient from a pre-filled syringe via an infusion line. The syringe pump applies a force to the plunger of the syringe to drive medication into the infusion line at a controlled rate. The head of the plunger is engaged by a plunger head actuator that is movable along a leadscrew extending parallel to the axis of the syringe. The head actuator is movable from an extreme position at one end of the pump, where it allows the largest syringe to be loaded into the pump with its plunger fully extended, to an extreme position at the opposite end of the pump, where it fully depresses the plunger of the smallest syringe. There is a risk, when the head actuator is being moved back to its loading position, that the head actuator may trap the user's finger or other objects between the actuator and the pump housing.


An image area dicriminating device for a digital copier, facsimile machine, scanner or similar imaging equipment. The device determines whether areas constituting an input image each has undergone dot processing or not automatically.

The present invention relates to an image area discriminating device for a digital copier, facsimile device, scanner or similar imaging equipment and, more particularly, to an image area discriminating device capable of automatically determining whether or not areas constituting an input image each has undergone dot processing.
A digital copier, for example, reads a document image pixel by pixel by using a CCD (Charge Coupled Device) image sensor or line sensor. An analog electric signal appearing on the output of the image CCD image sensor is converted into a digital signal and then subjected to various kinds of processing. The processed signal is fed to a recording device to print out the document image on a recording medium. It is a common practice with such a digital copier to record the processed signal in two levels, i.e., record/non-record or in multiple levels since the recording device is unable to readily change the density level pixel by pixel. However, the copier has to reproduce even halftone images which are often carried on photographs and other similar documents. Conventional implementations for rendering halftone by use of the bilevel or multilevel recording device include a dither method, density pattern method, submatrix method, and error scattering method.
So long as the density of an image changes slowly as is the case with a photograph, conventional halftone processing successfully reproduces the image relatively attractively. However, when a character or similar image whose density changes in definite two levels is reproduced, the reproduction suffers from various defects such as illigibly blurred contours and contaminated background. For this reason, characters or similar document images should be subjected to simple bilevel or multilevel processing rather than halftone processing. If the copier is provided with an extra switch for entering the presence/absence of halftone on a document, the operator can select an adequate copy mode matching the document by operating the switch. In practice, however, many documents, typically pamphlets, carry both of halftone images and bilevel images such as characters. Then, selecting the bilevel or multilevel mode would lower quality of resultant photographs, and selecting the halftone mode would lower the quality of resultant characters.
Another and serious problem with this type of digital copier is that when the change in the density of a document has periodicity, the period or pitch of the density change and the pitch at which the cells of a CCD line sensor or similar image sensor are arranged, i.e., sampling period interfere with each other to cause moire to appear on a recorded image. For example, an image printed on a document in the form of dots has periodicity concerning the density change, so that the period of the density change interferes with the sampling frequency of the line sensor to bring about the moire problem. Specifically, assuming that the resolution of the line sensor is 400 dots per inch (dpi), moire is apt to appear in an image signal when dots are printed on a document in a density close to the resolution, i.e., 133 lines (about 10.5 pixels per millimeter) to 200 lines (about 16 pixels per millimeter). While densities outside the above-mentioned range also cause moire to occur, moire is noticeable in such a particular range and causes the signal to change over a broad range. Dot printing itself is a kind of quasi-halftone representation and changes the density in two levels, i.e., ONE and ZERO (record and non-record) concerning each pixel. To render halftone, dot printing changes the average density of the entire assembly of pixels in multiple levels by changing the pitch or the size of dots. Therefore, apart from the moire problem, a dot image will be desirably reproduced if the signal is subjected to bilevel processing. In practice, however, a document on which dots are prined in a particular density suffers from moire when reproduced, as stated above.
On the other hand, when an image signal representative of a document is transformed to a bilevel or multilevel signal by halftone processing, moire does not appear or appears little on a reproduction since the halftone processing includes a step of averaging the densities of a plurality of pixels and a step of changing the threshold level. In this case, although the densities of a reproduction are rendered in quasi-halftone by dots, the dots on the reproduction are generated by halftone processing particular to a copier and, therefore, not the faithful replica of the dots on the document. It follows that when the image to be reproduced is an assembly of printed dots or an image reproduced by dot processing by a digital copier, a copy mode which effects halftone processing is preferable despite that such an image is bilevel concerning pixels.
It is desirable to process character portions by the simple bilevel or multilevel scheme and to process dot portions by the dither scheme or similar halftone processing scheme, as described previously. For this purpose, a document may be divided on an area basis. Specifically, if dot areas are detected and subjected to halftone processing while the other areas are subjected to simple bilevel processing, characters and photographs which are rendered by dots will be reproduced attractively, as disclosed in Japanese Patent Laid-Open Publication No. 279665/1988, for example. The method disclosed in this Laid-Open Publication is such that a bidimensional pattern of input image data is compared with a predetermined pattern to detect record dots and non-record dots and, based on the result of detection, whether or not the input image data is representative of a dot pattern is determined
Now, in an image undergone dot processing, record dots such as black pixels and non-record dots such as white pixels are arranged alternately at a predetermined pitch and a predetermined distance. Assume that a record pixel located at a given position and non-record pixels surrounding it are arranged in a particular pattern, or that a non-record pixel located at a given position and record pixels surrounding it are arranged in a particular pattern. If such a condition appears repetitively, the pixel of interest surrounded by the non-record pixels or the record pixels can be regarded as a pixel undergone dot processing. Therefore, whether or not an input image is a dot pattern can be determined if image data lying in a bidimensional area constitued by a pixel of interest, which is sequentially shifted, and surrounding pixels is compared with a predetermined record dot detection pattern and a non-record dot detection pattern. However, when an image undergone dot processing is actually read by an image scanner, the image pattern of the resultant signal noticeably changes to obstruct accurate identification of dots. This stems from the fact that since dot printing renders density in terms of the area of record dots in a predetemined small area, a change in the density of an image translates into a noticeable change in the shape of the dots. Especially, when the dot density is around 50% or so, nearby record dots such as black pixels or non-record dots such as white pixels are sometimes connected together. Then, neither the record dots nor the non-record dots can be detected.
To reduce the discrimination error particular to the dot density of 50%, the thresold level for binarizing image data into the record and non-record pixel levels may be adjusted. This, however, aggravates discrimination error when the dot density is higher or lower than 50%. To eliminate this dilemmatic situation, use may be made of at least two different threshold values, and two independent circuits for detecting record dots and non-record dots, respectively. Then, a dot pattern is identified on the basis of the results of detection of record dots and non-record dots with reference made to the image data derived from the two differnt threshold values.
Generally, when a dot image is read by a scanner, the resultant signal appears as shown in FIG. 14. As FIG. 14 indicates, the signal changes in the height of peaks and the depth of troughs as well as in duty in association with the density. Paying attention to the signal with a density level of 50%, for example, the height of a peak and the depth of a trough changes with the position of the image. When the signal with the density of 50% is binarized at the threshold level TH.sub.1, the leading portion Pa has a peak higher than the level TH.sub.1 an a trough lower than the level TH.sub.1 and, therefore, the peak and the trough appear as, respectively, a record pixel and a non-record pixel in the resultant bilevel signal. However, in the trailing portion Pb, the peak and the trough both are higher than the threshold level TH.sub.1 with the result that a non-record pixel does not appear in the resultant bilevel signal. More specifically, such a signal is binarized at the threshold level TH.sub.1, a dot (record dot) is detected in the leading portion Pa out of a record pixel and non-record pixel pattern, but no dots can be detected in the trailing portion Pb. Assume that the signal with the density of 50% is binarized at the other threshold level TH.sub.2. Then, both of the peak and trough in the leading portion Pa are lower than the level TH.sub.2, so that a record dot does not appear in the bilevel signal; in the trailing portion, since the peak is higher than the level TH.sub.2 and the trough is lower than the level TH.sub.1, the peak and the trough appear as, respectively a record pixel and a non-record pixel in the bilevel signal. In this manner, the threshold TH.sub.2 allows a dot (non-record dot) to be detected in the trailing portion Pb out of a record pixel and non-record pixel pattern while failing to do so when it comes to the leading portion Pa.
It follows that even with a dot image whose density is 50% either a record dot or non-record dot can be detected if the threshold values TH.sub.1 and TH.sub.2 are used to detect a dot which is a record dot and to detect a dot which is a non-record dot, respectively. When the density is low such as 20%, record dots are detected by use of the threshold value TH.sub.1 while, when the density is high such as 80%, non-record dots are detected by use of the threshold value TH.sub.2.
However, the conventional approach described above has some problems left unsolved, as follows. When record dots and non-record dots in a dot area do not appear as dots or appear in a defective pattern due to moire, they are not regarded as dots. The conventional approach is extremely susceptible to noise and is apt to regard even noise due to a solitary point of low density as a dot, resulting in frequent detection error. When a dot document having the same pitch and size in the main and subscanning directions is read, the density amplitude (MTF) usually differs from the main scanning direction to the subscanning direction, although the difference depends on the reading method and characteristic of the system. Further, it is likely that an area containing, for example, a line extending in the 45.degree. direction is misidentified.
When the magnification is changed, the configuration of a dot pattern is changed. Then, prepared patterns would fail to follow such a change in the configuration of a dot pattern and would thereby aggravate the misidentification of dots in the case of magnifications other than .times.1. Although this problem may be eliminated if the number of dot detection patterns is increased, this is not practicable without increasing the number of circuit components and elements.


A system for determining that a document B is a candidate for near duplicate to a document A with a given similarity level th. The system includes a storage for providing two different functions on the documents, each function having a numeric function value. The system further includes a processor associated with the storage and configured to determine that the document B is a candidate for near duplicate to the document A, if a condition is met. The condition includes: for any function ƒi from among the two functions, ƒi(A)−ƒi(B)≦δi(ƒ,A,th).

The need to detect near duplicate documents arises in many applications. Typical, yet not exclusive, an example being in litigation proceedings. In the latter one or both of the rival parties, initiates discovery proceedings which forces the rival party to reveal all the documents in his disposal that pertain to the legal dispute.
In order to meet the provisions of the discovery procedure, the disclosing party hands piles of documents, sometimes in order to duly meet the fall disclosure stipulations, or in certain other cases, as a tactical measure to flood the other party with numerous amounts of documents, thereby incurring the receiving party considerable legal expenses in the tedious task of determining which documents are relevant to the dispute under consideration. In many cases, out of the repertoire of disclosed documents, many are similar to each other. A preliminary knowledge which will group and/or flag documents that are similar one to the other, would streamline the screening process, since for example, if a certain document is classified as irrelevant, then probably all the documents that are similar thereto, are also deemed irrelevant. There are numerous other applications for determining near duplicate documents, sometimes from among a very large archive of documents (possibly at the order of e.g. millions of documents or more).

Method for determining near duplicate data objects


A method for ultrasonic imaging a volume behind a barrier includes placing an array of elements of a probe adjacent the barrier. The local thickness and the sound speed in the barrier are estimated. A plurality of sub-apertures are defined in the array of elements, each sub-aperture defined by a different sub-set of adjacent ones of the array of elements. Ultrasonic waveforms are collected from each of the sub-apertures by focusing each sub-aperture approximately at the inner surface of the barrier. The ultrasonic waveforms through each of the sub-aperture elements are combined to generate a combined A-mode waveform. A profile of an inner surface of the barrier adjacent the probe is extracted based upon the combined A-mode waveforms. A correction is calculated based upon the profile of the inner surface. The volume behind the barrier is scanned using beamforming based upon the correction to generate an image of the volume.

Noninvasive ultrasonic imaging of static foreign objects through the human skull or any other highly scattering multilayered solid structure (acoustical barrier) is difficult. The acoustical barrier possesses different acoustic impedance than the interfacing media, so implementation of conventional phased array imaging techniques results in significant image quality degradation. Where the intact human skull is the barrier, the foreign objects could be pieces of bone fragments, pieces of shrapnel, air bubbles, blood clots with high reflectivity, etc., which have higher/lower acoustic impedance than the surrounding brain tissue. The objects can be lodged at different depths, ranging from immediately under the skull up to several centimeters deep in the brain tissue. The thickness of the skull varies unevenly around the skull, which further causes image distortion.

Ultrasonic adaptive beamforming method and its application for transcranial imaging