Benzoic acid derivatives useful as intermediates for the preparation of drugs and agricultural chemicals, particularly compounds having herbicidal activity; and easy and economical processes for the preparation of the same. The processes are specifically those represented by reaction formula for the preparation of compounds represented by general formulae (1) and (6).

The present invention relates to benzoic acid derivatives useful as intermediates for the preparation of drugs and agricultural chemicals, particularly compounds having herbicidal activity, and to processes for the preparation thereof.
A method (A) of obtaining benzoic acid derivatives by reactions represented by the following reaction scheme,
between bicycloheptenone derivatives substituted with carboxylates and alcolates or the like is described in Tetrahedron, 42, 1741 (1986) and J. Org. Chem., 26, 2066 (1961).
However, there are no reports on reactions of bicycloheptenone derivatives substituted with hetero rings.
Known methods of dehalogenation of aromatic halogenated compounds include, for example, catalytic hydrogenolysis using palladium-carbon or Raney nickel as a catalyst, a method of using metal and metal salts such as lithium or sodium, hydrogenolytic reduction with tin hydride, reduction with metal-hydrogen complex compounds such as lithium aluminum hydride, and electrolytic reduction, which are described in Shin Jikkenkagakukouza, Vol. 14, Syntheses and Reactions of Organic Compounds [I] pages 22-30 (edited by the Chemical Society of Japan, published by Maruzen Co., Ltd.).
Substituted benzoic acid compounds, such as 4-alkylthiobenzoic acid derivatives, are important as intermediates for the preparation of agricultural chemicals and drugs. It has been desired to develop easy and industrially advantageous processes for the preparation of the said benzoic acid derivatives.
The present invention is directed to
(a) a benzoic acid derivative represented by Formula (1)
xe2x80x83(wherein R1 is hydrogen or C1-4 alkyl,
R2 is hydrogen or C1-6 alkyl, and
Q is an optionally substituted, saturated or unsaturated, 5- or 6-membered heterocyclic group containing 1 to 4 N, O or S atoms and combining with the benzene ring via a carbon atom);
(b) a process for the preparation of a benzoic acid derivative of the said Formula (1), characterized by acting a base on a bicycloheptenone derivative of Formula (2)
xe2x80x83(wherein R1 and Q are as defined above), in an appropriate solvent;
(c) a process for the preparation of a benzoic acid derivative of the said Formula (1), characterized by consisting of a stage of preparing a bicycloheptenone derivative of the said Formula (2) by hydrolysis of a bicycloheptene derivative of Formula (3)
xe2x80x83(wherein R1 are as defined above, and X is chlorine or C1-4 alkoxy and two X""s may join to form a C2-3 alkylenedioxy group optionally substituted with C1-4 alkyl), and of acting a base and water or alcohol on a bicycloheptenone derivative of the said Formula (2) in an appropriate solvent;
(d) a process for the preparation of a bicycloheptene derivative of the said Formula (3), characterized by reacting a cyclopentadiene derivative of Formula (4)
xe2x80x83(wherein X is as defined above) with an ethylene derivative substituted with a hetero ring, of Formula (5)
xe2x80x83(wherein R1 and Q are defined above);
(e) a bicycloheptenone derivative of the said formula (2); and
(f) a process for the preparation of a benzoic acid derivative of Formula (6)
xe2x80x83(wherein R1, R2 and Q are as defined above and R4 is C1-6 alkyl), characterized by reacting a 4,5-dichlorobenzoic acid derivative of the said Formula (1), with a mercaptan of Formula R4SH (wherein R4 is as defined above) and a base or with a salt of mercaptan of Formula R4SH (wherein R4 is as defined above)
In the definitions of the compounds of the said Formulae (1) and (2), which are the compounds of the present invention, the compounds of Formula (3) of their precursors and the compounds of Formula (6),
R1 is hydrogen, or C1-4 alkyl such as methyl, ethyl, propyl, isopropyl n-butyl isobutyl s-butyl or t-butyl;
a R2 is hydrogen, or C1-6 alkyl such as methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, s-butyl t-butyl, n-pentyl, isopentyl, neopentyl, n-hexyl or isohexyl;
X is halogen such as chlorine, or C1-4 alkoxy such as methoxy, ethoxy, propoxy, isopropoxy or butoxy;
Two X""s may join to form a C2-3 alkylenedioxy group, such as ethylenedioxy or trimethylenedioxy;
Further, the said C2-3 alkylenedioxy group may be substituted with C1-4 alkyl such as methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, s-butyl and t-butyl; and
Q is an optionally substituted, saturated or unsaturate 5- or 6-membered heterocyclic group containing 1 to 4 N, O or S atoms and combining with the benzene or bicycloheptane ring via a carbon atom.
Such hetero rings include, for example, 5-membered heterocyclic groups containing 1 to 4 N, O or S atoms, such as
2-furyl, 3-furyl,
2-thienyl, 3-thienyl,
2,3-dihydrofuran-2-yl, 2,3-dihydrofuran-3-yl, 2,3-dihydrofuran4-yl,2,3-dihydrofuran-5-yl, 2,5-dihydrofuran-2-yl, 2,5-dihydrofuran-3-yl,
2,3-dihydrothiophen-2-yl, 2,3-dihydrothiophen-3-yl, 2,3-dihydrothiophen-4-yl, 2,3-dihydrothiophen-5-yl, 2,5-dihydrothiophen-2-yl, 2,5-dihydrothiophen-3-yl,
pyrrol-2-yl, pyrrol-3-yl,
imidazol-2-yl, imidazol-4-yl, imidazol-5-yl,
2-imidazolin-2-yl, 2-imidazolin-4-yl, 2-imidazolin-5-yl,
pyrazol-3-yl, pyrozol-4-yl, pyrazol-5-yl,
oxazol-2-yl, oxazol-4-yl, oxazol-5-yl,
isoxazol-3-yl, isoxazol-4-yl, isoxazol-5-yl.
1,2,4-oxadiazol-3-yl, 1,2,4-oxadiazol-5-yl, 1,3,4-oxadiazol-2-yl, 1,2,3-oxadiazol-4-yl, 1,2,3-oxadiazol-5-yl, 1,2,5-oxadiazol-3-yl,
4-thiazolyl, 4-thiazolyl, 5-thiazolyl,
isothiazol-3-yl, isothiazol-4-yl, isothiazol-5-yl,
1,2,4-thiadiazol-3-yl, 1,2,4-thiadiazol-5-yl, 1,3,4-thiadiazol-2-yl, 1,2,3-thiadiazol-4-yl, 1,2,3-thiadiazol-5-yl, 1,2,5-thiadiazol-3-yl,
1,2,4-triazol-3-yl, 1,2,4-triazol-5-yl, 1,3,4-triazol-2-yl, 1,2,3-triazol-4-yl, 1,2,3-triazol-5-yl, tetrazol-5-yl,
2-pyrrolin-1-yl, 2-pyrrolin-2-yl, 2-pyrrolin-3-yl, 2-pyrrolin4-yl, 2-pyrrolin-5-yl,
2-oxazolin-2-yl, 2-oxazolin-4-yl, 2-oxazolin-5-yl, 3-oxazolin-2-yl, 3-oxazolin-4-yl, 3-oxazolin-5-yl, 4-oxazolin-2-yl, 4-oxazolin-4-yl, 4oxazolin-5-yl,
2-isoxazolin-3-yl, 2-isoxazolin-4-yl, 2-isoxazolin-5-yl,
3-isoxazolin-3-yl, 3-isoxazolin-4-yl, 3-isoxazolin-5-yl,
4-isoxazolin-3-yl, 4-isoxazolin-4-yl, 4-isoxazolin-5-yl,
2-thiazolin-2-yl, 4-thiazolin-4-yl, 4-thiazolin-5-yl,
2-isothiazolin-3-yl, 2-isothiazolin-4-yl, 2-isothiazolin-5-yl,
3-isothiazolin-3-yl, 3-isothiazolin-4-yl, 3-isothiazolin-5-yl,
4-isothiazolin-3-yl, 4-isothiazolin-4-yl, 4-isothiazolin-5-yl,
1-pyrazolin-3-yl, 1-pyrazolin-4-yl, 1-pyrazolin-5-yl,
2-pyrazolin-3-yl, 2-pyrazolin-4-yl, 2-pyrazolin-5-yl,
3-pyrazolin-3-yl, 3-pyrazolin-4-yl and 3-pyrazolin-5-yl; saturated 5-membered heterocyclic groups containing 1 to 4 N, O or S atoms, such as
2-pyrrolidinyl, 3-pyrrolidinyl,
2-tetrahydrofuranyl, 3-tetrahydrofuranyl,
2-tetrahydrothienyl, 3-tetrahydrothienyl,
2-oxazolidinyl, 4-oxazolidinyl, 5-oxazolidinyl,
3-isoxazolidinyl, 4-isoxazolidinyl, 5-isoxazolidinyl,
2-thiazolidinyl, 4-thiazolidinyl, 5-thiazolidinyl,
3-isothiazolidinyl, 4-isothiazolidinyl, 5-isothiazolidinyl,
2-imidazolidinyl, 4-imidazolidinyl,
1,2,4-oxadiazolidin-3-yl, 1,2,4-oxadiazolidin-5-yl, 1,3,4-oxadiazolidin-2-yl,
1,2,4-thiadiazolidin-3-yl, 1,2,4-thiadiazolidin-5-yl, 1,3,4-thiadiazolidin-2-yl,
1,3,4-triazolidin-2-yl,
1,3-dioxolan-2-yl, 1,3-dioxolan-4-yl,
1,3-dithiolan-2-yl, 1,3-dithiolan-4-yl, and
1,3-oxathiolan-2-yl; and
6-membered heterocyclic groups containing 1 to 4 N, O or S atoms, such as
2-pyridyl, 3-pyridyl, 4-pyridyl,
3-pyridazinyl, 4-pyridazinyl,
2-pyrimidinyl, 4-pyrimidinyl, 5-pyrimidinyl,
pyrazin-2-yl,
2H-pyran-3-yl, 2H-thiopyran-3-yl,
2-piperidinyl, 3-piperidinyl, 4-piperidinyl
2-piperadinyl,
2-morpholinyl, 3-morpholinyl,
5,6-dihydro-4H-1,3-thiazin-2-yl,
2-tetrahydropyranyl, 3-tetrahydropyranyl, 4-tetrahydropyranyl,
2-tetrahydrothiopyranyl, 3-tetrahydrothiopyranyl and 4-tetrahydrothiopyranyl.
These groups may have one or more, same or different, substituents at arbitrary positions of the hetero rings. Such substituents include, for example, C1-4 alkyl such as methyl, ethyl, propyl isopropyl, n-butyl, isobutyl, s-butyl and t-butyl, and C1-4 haloalkyl such as chloromethyl, dichloromethyl, trichloromethyl, fluoromethyl, difluoromethyl, trifluoromethyl, 1-fluoroethyl, 1,1-difluoroethyl, 2,2,2-trifluoroethyl and pentafluoroethyl.
Q is more preferably one of the following groups represented by Q-1 to Q-9.
In the above formulae, R3 is, for example, C1-4 alkyl such as methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, s-butyl or t-butyl, or C1-4 haloalkyl such as chloromethyl, dichloromethyl, trichloromethyl, fluoromethyl, difluoromethyl, trifluoromethyl, 1-fluoroethyl, 1,1-difluoroethyl, 2,2,2-trifluoroethyl or pentafluoroethyl, and n is 0 or an integer of 1 or 2.
Further, in the said Formula (6), R4 is C1-6 alkyl such as methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl s-butyl, t-butyl, n-pentyl, isopentyl, neopentyl, n-hexyl or isohexyl.
The compounds of the present invention, represented by the said Formulae (2) and (3), may have stereoisomers, depending on substituents at positions 5 and 6. They are all covered by the present invention.
The compounds of the present invention may be produced by the following processes:
(Process 1) Process for the Preparation of a 4,5-dichlorobenzoic Acid Derivative from a Bicycloheptenone Derivative
(wherein R1, R2 and Q are as defined above).
A bicycloheptenone derivative (2) of Formula (2) is reacted with a base and water or alcohol in an appropriate solvent to give a compound of Formula (1).
Bases used for this reaction include, for example, alkali metal alcolates such as sodium methylate, sodium ethylate and potassium t-butoxide; alkali metal hydroxides such as sodium hydroxide and potassium hydroxide; alkaline earth metal hydroxides such as calcium hydroxide; alkali metal carbonates such as sodium carbonate, potassium carbonate and sodium hydrogen carbonate; and alkaline earth metal carbonates.
An amount of a base used is preferably 2 to 5 equivalents to 1 mole of a bicycloheptenone derivative (2).
Solvents able to be used for the reaction include alcohols such as methanol, ethanol, propanol, isopropanol, butanol and t-butanol; ethers such as diethyl ether and tetrahydrofuran (THF); hydrocarbons such as benzene and toluene; acetonitrile, dimethylformamide (DMF), water, toluene, benzene and the like, or mixtures of 2 or more of these solvents.
In the aforementioned reaction, it is particularly preferable to use alcoholic solvents, that is, alcohols, or mixed solvents of alcohol and other solvents such as water and alcohol or alcohol and ether.
In the above reaction, an ester (COOR2) having a portion corresponding to an alcohol (R2OH) used or the alkoxide portion of a metal alkoxide (MOR2) used can be obtained; for example, a methyl ester is obtained with the use of methyl alcohol and an ethyl ester from ethyl alcohol.
More preferred combinations of a base and a solvent include, for example, sodium methoxide and methanol (or a mixed solvent of methanol and other solvents), sodium ethoxide and ethanol (or a mixed solvent of ethanol and other solvents), sodium hydroxide and alcohol (or a mixed solvent of alcohol and other solvents), potassium hydroxide and alcohol (or a mixed solvent of alcohol and other solvents), and potassium t-butoxide and butanol.
In the case of the use of mixed solvents or aqueous solvents, carboxylic acids (R2=H) can be obtained. Solvents used together with water are favorably alcohols and ethers. As for bases, the aforementioned hydroxides or carbonates are preferably used.
In the case of the use of metal alkoxides, it is preferable to use corresponding alcohols, as described above. It is of course possible to use other alcohols.
Preferred reaction temperatures are between xe2x88x9210xc2x0 C. and the boiling point of solvents used.
(Process 2)
(wherein R1, R2, Q and X are as defined above.)
A bicycloheptenone derivative (2) can be obtained by hydrolysis of a bicycloheptene derivative (3) with an acid such as hydrochloric acid or sulfuric acid.
That is, a compound (2) can be obtained by hydrolyzing a compound (3) without using a solvent or with a solvent including alcohols such as methanol, ethanol and t-butanol, ethers such as diethyl ether and tetrahydrofuran (THF) or aromatic hydrocarbons such as benzene and toluene, or a mixed solvent of two or more of these solvents, at temperature between xe2x88x9210xc2x0 C. and the boiling point of solvents used.
After this, a target benzoic acid derivative can be prepared in the same way as that described in Process 1 above.
(Process 3)
(wherein R1, R2, Q and X are as defined above.)
A Diels-Alder reaction of a cyclopentadiene derivative (4) and an ethylene derivative substituted with a hetero ring (5) gives a bicycloheptene derivative (3).
The Diels-Alder reaction can be carried out according to methods described, for example, in Tetrahedron, 42, 1741-1744 (1986) or J. Org. Chem., 26, 2066-2072 (1961).
In the above reaction, cyclopentadienes and ethylene derivatives are reacted while heating. A molar ratio of the ethylene derivatives used in the reaction is 0.5 to 10 times in equivalent, preferably 1 to 3 equivalents, to 1 mole of cyclopentadienes. The reaction is carried out at temperature between room temperature and 25xc2x0 C., more preferably between 70xc2x0 C. and 200xc2x0 C.
Although this reaction is usually carried out without solvents, solvents may be used. Examples of solvents used include aromatic hydrocarbons such as benzene, toluene, xylene, chlorobenzene and dichlorobenzene; alcohols such as ethanol, n-propyl alcohol, ethylene glycol, 1,3-butanediol and ethylene glycol monomethyl ether; ethers such as dimethoxyethane, dioxane and diethylene glycol dimethyl ether, amides such as N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrolidone and N,N-dimethylimidazoline; hydrocarbons containing sulfur such as dimethylsulfoxide and sulfolane, and water.
The reaction proceeds more smoothly by adding a polymerization inhibitor such as hydroquinone in the presence of a base such as sodium hydrogen carbonate, potassium hydrogen carbonate, sodium carbonate or potassium carbonate.
After this, a target benzoic acid derivative can be produced in the same way as that in Process 2.
A compound of Formula (5), a starting material, can be prepared according to methods described, for example, in the following papers:
Chim. Ind. (Milan), 52 (1), 56 (1977): Preparation of 3-(1-propenyl)-1H-pyrrole;
Zh. Organ. Khim., 2, 417-423 (1966): Preparation of 5-(1-propenyl)-isoxazole;
J. Org. Chem., 62, 3671-3677 (1997): Preparation of 3(1-propenyl)-2-isoxazoline;
Heterocycles, 22 (11), 2475-2478 (1984): Preparation of 4(1-propenyl)pyridine; and
Heterocycles, 29(1), 103-114 (1989): Preparation of 5-(1-propenyl)-oxazole.
(Process 4)
(wherein R1, R2, R4 and Q are as defined above.)
In the process, a 4,5-dichlorobenzoic acid derivative of Formula (1) is reacted with an excessive amount of alkane thiol of Formula R4SH (R4 is as defined above) in an appropriate inert solvent in the presence of a base, to give a 4-alkylthiobenzoic acid derivative of Formula (6).
While doing so, the reaction proceeds more smoothly under the irradiation of light (of a specified wavelength). Various light sources can be used, including sunlight, fluorescent lights, mercury lamps, arc lamps and incandescent lamps. It is preferable to carry out the reaction under inert gas atmosphere, after the reaction system is sufficiently degassed.
The reaction may sometimes proceed more smoothly by adding water of 0.1 to 5 times in equivalent to the amount of 4,5-dichlorobenzoic acid derivative (1).
Particularly preferred solvents used for this reaction are amides, such as dimethylformamide DMF), N,N-dimethylacetamide and N-methylpyrolidone. However, solvents used are not restricted to them.
Examples of bases used include hydroxides such as sodium hydroxide and potassium hydroxide; carbonates such as sodium carbonate, sodium hydrogen carbonate, potassium carbonate and potassium hydrogen carbonate; and metal alcolates such as sodium methylate, sodium etheylate and potassium t-butoxide. In this case, a salt of alkane thiol, such as sodium or potassium salt of alkane thiol, prepared from an alkane thiol and a base beforehand, can be used for the reaction.
Amounts of base and alkane thiol used are preferably 2 to 20 equivalents to that of 4,5-dichlorobenzoic acid derivative (1).
Benzoic acid derivatives of Formula (6) can be produced by isolation of Compound (7) followed by reduction, as shown in the following reaction scheme:
To produce a compound of Formula (7), an equivalent of a compound of Formula (1) is reacted with about 1 to 3 equivalents of an alkane thiol of Formula R4SH (R4 is as defined above) in an inert solvent in the presence of an appropriate base.
In the reduction reaction from a compound of Formula (7) to a compound of Formula (6), the same alkane thiol (R4SH) as that used in the previous reaction can be used as a reducing agent. Further, other reducing agents such as hydrogen sulfide and aromatic thiols can be employed.
A compound of Formula (6) can be derived to a corresponding SO2R4 compound (8) by oxidation reaction of the SR4 group. This oxidation reaction may be carried out using an oxidizing agent including peroxides such as hydrogen peroxide, peracetic acid, perbenzoic acid and m-chloroperbenzoic acid, and hypochlorites such as sodium hypochlorite and potassium hypochlorite, in an inert solvent including water, alcohols such as methanol and ethanol organic acids such as acetic acid, and halogenated hydrocarbons such as dichloromethane, chloroform and carbon tetrachloride. The reaction proceeds smoothly in the temperature range from 0xc2x0 C. to the boiling point of the solvent used.
Further, a SO2R4 compound (8) can be obtained by oxidation of a compound of the said Formula (7) and then a reduction reaction for dechlorination.
(wherein R1, R2, R4 and Q are as defined above.)
A compound of Formula (9) can be produced by oxidation of a compound of Formula (7). This oxidation reaction may be carried out using an oxidizing agent including peroxides such as hydrogen peroxide, peracetic acid, perbenzoic acid and m-chloroperbenzoic acid, and hypochlorites such as sodium hypochlorite and potassium hypochlorite, in an inert solvent including water, alcohols such as methanol and ethanol, organic acids such as acetic acid, and halogenated hydrocarbons such as dichloromethane, chloroform and carbon tetrachloride. The reaction proceeds smoothly in the temperature range from 0xc2x0 C. to the boiling point of the solvent used.
The next dechlorination of a compound of Formula (9) is carried out by such a method as catalytic hydrogenolysis using Raney nickel as a catalyst, method of using metal and metal salts such as lithium and sodium hydrogenolytic reduction with tin hydride, reduction with a metal-hydrogen complex compound such as lithium aluminum hydride, or electrolytic reduction, described in Shin Jikkenkagakukouza Vol. 14, Syntheses and Reactions of Organic Compounds [I] pages 22-30 (edited by the Chemical Society of Japan, published by Maruzen Co., Ltd.).
The compounds of the present invention, intermediates and others can be obtained with usual post-treatments after the completion of the reactions.
The structures of the compounds of the present invention, intermediates and others were determined by IR, NMR, MS and other means.
The present invention is described in more detail in reference to Examples and Reference Examples.
In Examples, of the compounds of the present invention, (1S, 4R, 5R, 6S) and (1R, 4S, 5S, 6R) isomers are represented as xe2x80x9ctransxe2x80x9d, and (1S, 4R, 5R, 6R) and (1R, 4S, 5S, 6S) isomers as xe2x80x9ccisxe2x80x9d.

Benzoic acid derivatives and processes for the preparation thereof


A toy figure is disclosed comprising upper and lower torso sections, pivotally connected along a plane intersecting the longitudinal axis of the figure at a predetermined angle, whereby the figure is convertible from a standing configuration to a sitting configuration by rotating the torso sections 180 degrees with respect to one another. The structure is provided with a directionally oriented head component which can be adjusted into various attitudes and angles. A positive frictional pivot joint between the head and shoulder socket makes the head repositionable yet retains its position at the desired attitude and angle. The plane between the upper and lower torsos extends downardly from the front to the back of the figure at a 45 degree angle, whereby the bottom torso, when pivoted 180 degrees with respect to the top torso section, is in directional conformity with the head component.

1. Field of the Invention
The present invention relates to Toy Figures which are manufactured from plastic material, and more specifically to such figures which are reconfigurable from a standing to a sitting position.
2. The Prior Art
Toy Figures which are reconfigurable from a standing to a sitting position are well known in the toy industry. One type of such a figure is repositionable because of its elastomaric composition, which provides sufficient resiliency to facilitate a direct bending of the figure at the midsection. When it is desirable to have a toy figure manufactured out of hard plastic material, however, resilient bending of the figure directly into a sitting position is precluded.
U.S. Pat. No. 3,706,155 demonstrates a second general approach to reconfiguring a figure from a standing to a sitting position; that is, rotating the bottom torso 180 degrees with respect to the top of the figure. As taught by the above identified patent, the figure is separated at its midsection into upper and lower torso sections. The dividing line between the upper and lower torso is a pivot plane which extends downward from the back to the front of the figure. In order to reconfigure the figure into a sitting orientation, the lower torso is rotated 180 degrees with respect to the top torso section, and thereafter the head is pivoted 180 degrees so as to resume directional conformity with the lower torso section.
While the above patented invention works well and as intended, it has several deficiencies in its manner of operation. First, the structure is such that a 180 degree pivoting of the lower torso section with respect to the upper torso section results in the bottom torso legs being directionally opposite to the orientation of the head. This inconsistency must thereafter be corrected by rotating the head 180 degrees. In order to facilitate rotation of the head, the joint between the head and the shoulders must be of a simple neck plug configuration. Stated differently, the user of such figures may at times wish to reposition the head into various attitudes and orientations, and to retain the head in such position after the figure is transformed from a sitting to standing position. However, the structure of the above identified patented invention necessitates that the head be rotated 180 degrees so as to be brought back into directional conformity with the lower torso. This necessity makes repositionment a two-step procedure. A final deficiency is that the patented article requires the upper torso to be directionally neutral, so that the upper torso and head remain consistent when the head is rotated 180 degrees. Such a restriction, however, severely limits the degree of design detail which can be incorporated into the upper torso and arms, and therefore the toy's appeal.


A laser pointer is disclosed consisted of a laser module, a housing, a toggle switch, a push button, a constant power output control circuit, a ballpoint pen, a battery set, and a rotary cap, wherein the housing has chambers to hold the laser module, the battery set, and the push button ballpoint pen, and a clip for hanging; the toggle switch has a press rod controlled by a button to press a leaf spring on a PC board so as to electrically connect the battery set to the laser module in driving the laser module to emit a laser beam for pointing to things.

The present invention relates to laser pointers, and more particularly to a pen-like laser pointer with a constant power output control used for pointing to things on a map, chart, blackboard, etc., by means of the laser beam generated thereby.
Various laser pointers have been disclosed, and have appeared on the market. These laser pointers are commonly comprised of a metal casing having a laser diode connected to a trigger circuit thereof and controlled by a press contact switch to generate a laser beam for pointing to things on a map, chart, blackboard, etc. As the press contact switch is fastened to the rear end of the casing, it may be easily triggered by error. Furthermore, the use of the metal casing greatly increases the cost of this laser pointer.

Laser pointer with a constant power output control


Methods, apparatus and processes for three phase contacting and reactions in a cross flow reactor with reduced feed vaporization, low pressure operation, higher liquid holdup, lower reactor pressure drop, low severity operation, and reduced product inhibitory effects. A cross flow reactor for three phase catalytic hydroprocessing, having at least one reactor stage is disclosed. The reactor stage has a central gas distributor with perforated lateral surface for distributing gas, a middle region accommodating a packed catalyst bed, and an outer gas space for removal of effluent gases from the middle region. The middle region receives a liquid reactant and gas from central gas distributor to carry out three phase catalytic hydroprocessing reaction.

Gas-liquid-solid catalytic reactors, also called three-phase reactors, are widely used in various industries, such as refining, chemical, and petrochemical industries, to carry out various reactions. In refining gas liquid three phase reactors are used for hydroprocessing of hydrocarbon feedstock. Hydrocarbon feedstock is generally available as crude oil, which includes various petroleum fractions like gasoline, kerosene, diesel, wax, and heavy oils, along with unsaturated hydrocarbon compounds, such as olefins and aromatics, and hetero atom impurities, such as sulphur, nitrogen, etc. The hydrocarbon feedstock has to be hydroprocessed to a suitable quality for production of various petroleum products. For example, long chain hydrocarbons in heavy oils have to be broken down into smaller chain hydrocarbons, the impurities have to be removed and the unsaturated compounds have to be saturated. Such reactions are carried out using the three-phase reactors.
These reactors can be operated in co-current or counter-current mode. If the reactor is designed in such a way that the reactants flow in the same direction within the reactor, it is termed as a co-current three-phase reactor. When the direction of flow of reactants is opposite to each other in the reactor, it is known as counter-current three-phase reactor.
The three-phase packed bed reactors, also referred to as trickle bed reactors, are commonly used for hydroprocessing. Hydroprocessing is a highly exothermic process involving treatment of hydrocarbon feedstock with hydrogen in the presence of a suitable catalyst to achieve various objectives like desulphurization, denitrogenation, hydrogenation, hydrocracking, and isomerization for production of fuels and lubes of desired quality. It is generally carried out in adiabatic mode with intermediate quenching to check the rise in temperature due to the exothermic nature of the reactions. In hydroprocessing, hydrogen react with hetero atoms to produce gases like hydrogen sulphide and ammonia, thereby removing the hetero atoms from the hydrocarbon feedstock. Further, the treatment with hydrogen also results in hydrogenation of unsaturated hydrocarbon molecules and hydrocracking of long chain molecules.
Conventionally, hydroprocessing of hydrocarbon feedstock is done in three-phase packed bed reactor with co-current down flow mode of operation at elevated pressure and temperature. In the conventional co-current down flow hydroprocessing, high gas to oil ratio is used, and thus, gas phase is continuous phase and liquid is dispersed. Consequently, it leads to undesired vaporization of hydrocarbon feed during hydroprocessing of hydrocarbon feedstock. In addition, higher gas/oil ratio leads to increased pressure drop across the reactor, and thus, a high pressure differential within the reactor. Further, the co-current reactors have a high mean flow path for the reactant gas, which leads to additional pressure drop along the length of the reactor and significant difference in pressure of the reactor at the entrance and exit.
On the other hand, as the hydroprocessing reactions proceed within the reactor, more and more of hydrogen sulphide (H2S) and ammonia (NH3) are generated. As a result, there is increase in the concentration of H2S and NH3, and thus, the partial pressure of hydrogen is reduced. The reduced partial pressure of hydrogen leads to reduced rate of desulphurization, denitrogenation, and saturation reactions in the reactor. This often leads to high severity operation to meet product quality specifications, in turn causing nonselective cracking of hydrocarbon feedstock to light ends and shorter run lengths due to increased catalyst deactivation rates.
Further, gas phase holdup increases continuously from reactor entrance to exit as gas phase hydroprocessing products are generated. This results in inefficient utilization and insufficient wetting of catalyst by liquid phase reactant and higher catalyst requirement for given through put and desired product quality and yields. In addition, these units are energy intensive and part of this energy is unnecessarily utilized for vaporization of feed as reactant gas and feed are heated together in reactor feed furnace.
On the other hand, in counter-current packed bed reactors, the reactors are designed in such a way that the gas and liquid reactants are introduced from vertically opposite ends of the reactor into the reactor column and flow in opposite directions. Counter current reactors facilitate ultra-low sulphur levels to be achieved efficiently while treating hydrocarbon feedstock since, during operation; a major part of the middle region is in an H2S lean environment. However, these reactors also have high differential pressure and a limited range of gas-liquid flow rates under which they can operate without flooding. Flooding typically occurs when the flow rate and pressure of the gas phase is high enough to prevent the downward flow of the liquid phase. Due to flooding, the gas tends to lift the liquid out of bed and there is poor contact between the two phases. As a result, the reactors have to be operated at lower flow rates, which make them commercially unviable. Counter-current hydroprocessing has not achieved commercial acceptability as the drawbacks associated outweigh the benefits.
Further, in both co-current and counter-current reactors, dry spots are created in the middle region during operation due to uneven distribution of feed, feed vaporization, and higher gas holdup. Dry spot is a region in the middle region where the catalyst is devoid of liquid hydrocarbon feed and so cannot participate in the reaction. The occurrence of dry spots leads to under utilization of catalyst in the reactors, which can be significant on an industrial scale. Thus, in both counter-current and co-current reactors, a part of the hydrocarbon feed is either wasted or incompletely processed. To ensure the required quality of treated hydrocarbon, the output stream has to be hydroprocessed again in multiple stages to overcome thermodynamic equilibrium, which increases the cost of operation.
To overcome some of these difficulties, state-of-the-art trickle bed reactors are being designed with inter bed separators for removal of inhibitory compounds, multi stage operation with temperature control and catalysts to overcome equilibrium limitations and maximizing intermediates, efficient gas liquid distributors and internals for improved gas liquid distribution and catalyst wetting. In similar lines, hybrid contacting pattern along with inter-stage separators were described in prior art to address inhibition effects during desulfurization and separation of light ends formed during cracking before passing feed to next stage/reactor.
A third type of reactor, called radial flow or cross flow reactor has been proposed in the art to overcome some of the disadvantages of the counter-current and co-current reactors. In the radial reactor, the liquid and the gas streams flow in radial direction. Radial flow reactors are commercially used for applications such as naphtha reforming process, ammonia synthesis, ethyl benzene dehydrogenation etc. While theoretically such reactors have reduced pressure drops, the commercial use of such reactors is limited to high throughput application and low pressure drop requirements.
Recent technologies advocate liquid phase hydroprocessing wherein the liquid is pre-saturated with hydrogen and hydroprocessing is carried out in absence of gas phase in the reactor. The advantages suggested are near isothermal conditions in the reactor and avoiding gas compression and gas recycle. However, as the solubility of hydrogen is limited good amount of product needs to be recycled for carrying the soluble hydrogen. The liquid recycle requirement for hydrogen intensive applications such as cracking and treating of high sulfur feedstocks is expected to be still higher. Further the inhibitory effects of NH3 and H2S are expected to be similar to conventional trickle bed reactors.
Therefore it is desirable to have improved multiphase reactor design which overcomes shortcomings of prior art and enables low severity operation, minimizes feed vaporization and non selective cracking, enhances reaction rates for desired reactions, minimizes reactor pressure drop and reactant gas consumption. Thus, there remains a considerable need for apparatus and methods for efficient hydroprocessing of hydrocarbons.

Methods and apparatus for three phase contacting and reactions in a cross flow reactor


A feedstock for an additive manufacturing process includes a pre-ceramic polymer intermixed with a base material. A method of additive manufacturing includes melting and pyrolizing a feedstock containing metal and a pre-ceramic polymer. An article of manufacture includes an additive manufacturing component including a pyrolized feedstock.

The present disclosure relates generally to additive manufacturing, and more particularly to a feedstock therefor that includes a pre-ceramic polymer.
Laser Powder Bed Fusion (LPBF) is an additive manufacturing process involving the construction of a three-dimensional article by selectively projecting a laser beam having the desired energy onto a layer of feedstock particles. When coupled with computer aided design apparatus, LPBF is an effective technique for producing prototype as well as production articles. Other such additive manufacturing processes utilize an electron beam within a vacuum.
Various nanoparticles have heretofore been included in feedstock, but proper mixing and distribution of the particles in a bulk feedstock have been difficult to achieve.

Additive manufacturing of metal matrix composite feedstock


A method of fabricating nanostructure bodies by integrating the steps of attriting precursor nanometer-sized particulate materials, desorbing the exposed surfaces of the attrited nanoparticulates, adsorbing a surfactant on at most 50% of the desorbed surfaces and dispersing the surfactant-coated nanoparticulates in an organic matrix to form a homogeneous thermoplastic compound from which green bodies are shaped, dewaxed and sintered.

U.S. Patent Documents
Not Applicable.
Not Applicable.
1. Field of Invention
The present invention relates to the fabrication of articles from nanoparticulate materials. More particularly, the present invention relates to a method to overcome the problems of the prior art in controlling aggregation, contamination and pyrophoricity during handling of nanoparticulate materials and the fabrication of articles therefrom.
2. Description of Prior Art
In a broad sense, nanomaterials, nanocrystalline or nanostructured materials or simply nanostructures refer to dense materials with grain sizes in the nanometer (one billionth of a meter) range. The designation xe2x80x98nanoparticulatesxe2x80x99 is generally applied to any particulate matter with an average dimension below one micrometer. In the literature, the terms nanoparticulates, submicrometer powders, nanopowders, nanoscale powders or nanocrystalline powders are often used interchangeably. The terms nanosuspension or nanodispersion usually refer to suspensions of discrete nanoparticulates, in either a liquid or in a solid matrix.
Nanoscale powders are not new. The use of lampblack, a carbon nanoscale powder with particle sizes in the 10-100 nm, to make Chinese ink, predates the Christian era by thousands of years. Nanoscale metal oxides have been used in the paint industry for centuries, whereas nanoscaled silica powders are used as filler additives to tailor the rheological properties of a variety or organic suspensions. In the hardmetal industry ultrafine carbide and nitride powders are used to make cutting tools with increased strength and extended economic life over those produced from conventional powders. More recently, the use of oxide nanopowders in optics, electronic, and in cosmetics for UV protection is well established.
It is well known that a decrease in particle size results in enhanced sintering kinetics of particulate materials. When particle size reaches the nanometer range, full densification is often possible at substantially lower temperatures than those needed for sintering coarse-grained particulates. This is because nanoparticles imply shorter diffusion lengths while promoting boundary diffusion mechanisms. In addition to savings in energy, lower sintering temperatures also result in reduced contamination, stresses and cracking during cooling.
The enhanced sintering kinetics of nanoparticulate materials are already exploited in the microelectronic packaging industry, where metal alloy nanopowders are incorporated in cold-weldable welding pastes to achieve ductile and electrically conductive metal to metal bonds.
In the refractory metal industry, a decrease of several hundreds of degrees in the sintering temperature is achievable when standard 2 xcexcm tantalum powder used to produce tantalum capacitors is replaced with a 50 nm nanopowder.
Aside from geometric considerations, the prefix xe2x80x98nanoxe2x80x99 also implies dramatically improved material properties as inferred from the well-known Hall-Petch relationship according to which a material""s strength increases proportionally to the inverse square root of its grain diameter.
Hence, interest has been growing in nanoparticulate materials stemming from the fact that novel phenomena are being discovered at the nanoscale level, and there is immense potential for improving structural and functional properties of components and devices by xe2x80x98nanostructuringxe2x80x99 as nanostructures can generate superplastic or ultra-high strength, tough materials. Extrapolations based on reducing grain size have produced forecasts of 2-7 times higher hardness and 2-3 times the tensile strength of parts produced from conventional powders.
For example the yield strength of an 80 nm iron nanopowder sintered to 99.2% of theoretical density is about 2.4 GPa, roughly five times that of conventional iron with a particle size in the 25 xcexcm range.
The improved material properties of nanostructures have already found applications in many different fields of industry and technology. For example nanograined powders are already used in hydrogen storage technology. Another fast growing field of application is that of nanopowder-polymer composites for microelectronic applications. Using metallic nanopowders dispersed in polymers allows the fabrication of electrically conductive adhesives, radio frequency shielding polymers, and magnetic polymeric layers. Another area of strong interest is the fabrication of lightweight electrical wires using conductive nanopowders in a polymer matrix. These extrinsically conductive polymer wires with nanoparticulate fillers exhibit improved electrical percolation. Since the volume of filler material needed to provide conductivity can be reduced by over 50%, the intrinsic flexibility, strength and toughness of the polymer matrix material is retained.
The use of nanopowders as reinforcing phase in nanocomposites is a fast developing technology where the vastly increased interfacial area between the nanoparticles and the matrix material leads to improvements in the amount of energy absorbed during mechanical stress. This is especially useful in applications such as ballistic armor protection, where improved energy absorption under high strain rate conditions leads to increased ballistic impact resistance. Furthermore the reduction in the amount of filler phase necessary to reinforce the polymer matrix reduces overall component weight.
The fine size of nanoparticulates also allows for the design of strengthened optically transparent components such as aircraft canopies. In this case the nanoparticle reinforcing agent is so fine that interference with the wavelengths of the visible light spectrum is minimized or eliminated.
Another exciting field of application is that of lithium ion batteries where nano-vanadium pentoxide has been shown to possess electrochemical properties that are different from those of commercial coarse-grained V2O5 powders, and these properties can be attributed to the structure of the nanoparticles. The discharge-charge voltage curve of nano-V2O5 is continuous whereas, in contrast, coarse-grained V2O5 has a stepwise curve which is unsuitable for lithium ion batteries. For the same number of discharge charge cycles, the capacity of nano-V2O5 is 60% higher than that of commercial powder. Furthermore irreversible losses are also much smaller when using nano-V2O5.
In the area of materials joining, copper, gold, nickel, tin and solder powders are routinely formed into pastes and used for electronics interconnects. The pastes are printed on ceramics such as aluminum oxide, and more recently aluminum nitride, to produce highly dense, so called thick film circuits. The requirement to shrink circuits and increase functionality has resulted in a continuing search for new and improved processes. One of the latest developments is in copper based pastes that can be applied to ceramic substrates at temperatures substantially below those currently used to manufacture thick film circuits. Lower temperatures are desirable because many electronic components are degraded by excessive temperatures. The lower sintering temperatures also allow environment-unfriendly lead based solder pastes to be phased out. Nanoparticulate-based joining formulations offer the potential to tailor the metallurgy and to lower the brazing temperature.
Nanoaluminum powders are also advantageously used in solid propellant formulations, doubling the burning rate as compared with that of compositions based on micrometer size aluminum. High burning rates increase thrust and speed of response. Adding nanoaluminum to hydrogen and kerosene burning with liquid oxygen increases the amount of energy released, resulting in smaller fuel tanks and shorter, lighter weight rockets.
There are many methods to produce nanopowders, most of them recent developments. Conventional powder fabrication techniques such as gas or water atomization fail in the submicrometer range, as they usually have a lower particle size limit of 1-5 xcexcm. The past decade has seen significant effort in developing technology for synthesizing and processing materials at the nanometer scale.
One of several newer approaches is the inert gas condensation (IGC) method, which consists of evaporating and condensing the respective material in a vacuum chamber with a low partial pressure of inert gas (e.g. 10 mbar helium). With IGC, high quality powders with low chemical impurity levels and low contents of oxides or nitrides from the production process can be produced.
In a variation of this process metal particles are embedded in an organic matrix by evaporating both the metal and an organic liquid in the same vacuum vessel and subsequent co-condensation of the metal and the organic vapor under inert gas or vacuum. This process allegedly enables production of metal particles without agglomeration or oxide layers in an organic suspension. Particle size distribution is narrow, with a mean particle size in the range 2-50 nm.
Another process, the flame or plasma reduction method, uses the decomposition and reduction of metal salts in a gas flame or plasma. Sodium reduction of halides has been standard industrial practice for decades for synthesizing materials like titanium and zirconium. In one variation, the sodium/halide flame and encapsulation (SFE) technique uses sodium reduction of metal halides to produce the metal or, if the reaction occurs in the presence of a non-metal, a ceramic. The byproduct of the chemistry is salt, typically sodium chloride, which is used to encapsulate the particles within the flame.
Other processes include the chemical vapor reaction (CVR) method, which uses the reaction of metal chlorides and hydrogen in a hot wall reactor and the combustion flame chemical vapor condensation (CF-CVC) process. The latter purportedly has the ability to minimize the extent of particle aggregation. Still other techniques used are the pulsed plasma jet process and the electro-explosion of wire (EEW) process where an electrical pulse is applied to a wire.
Finally, mechanical milling or attriting, probably the oldest and best known of comminuting techniques, can produce large quantities of nanocrystalline materials with grain sizes below 100 nm from commercial coarse-grained metallic or ceramic powders as the starting materials. Mechanical milling is attractive because it has the advantage of being a simple and inexpensive process usually performed at room temperature and which can be readily scaled up for mass production.
Virtually all the problems in the production and processing of nanopowders stem from their high reactivity and worsen with decreasing particle size.
As the main quality issue, the pick-up of oxides or nitrides during processing or storage can be a serious problem. In most cases the incorporated oxygen has deleterious effects on the mechanical properties of the end product. To reduce contamination, nanopowder production and consolidation operations are mostly performed under inert gas atmosphere.
The purity requirement of nanoparticulate materials is application dependent as well. For advanced materials a specification of total metallic impurities less than 100 ppm is common.
Nanoparticulate materials have a strong tendency to form aggregates or agglomeratesxe2x80x94most authors use the terms indiscriminatelyxe2x80x94which have a deleterious effect on powder processibility and end product quality. This is particularly relevant in applications such as rechargeable batteries, where a high packing density of the nanoparticulates is essential.
The high reactivity of nanoparticulate materials also leads to undesirable grain growth. The driving force for grain growth increases as grain sizes decreases, such that the advantage nanophase materials have in sinterability can be lost due to concomitant grain growth that destroys the desirable nanoscale grain size, defeating any efforts to form nanostructures.
Therefore, to maintain nanoscale grain size, consolidation temperatures often have to be limited to below 600xc2x0 C., and typically to the 400-500xc2x0 C. range.
Early work on the consolidation of metallic nanophase powders employed exotic techniques, such as shockwave compacting, to overcome the difficulties in maintaining nanophase grain size. Subsequent attempts using various techniques such as hot pressing, hot extrusion, sinterforging, hipping, etc. produced consolidated products that are either porous (around 90% of theoretical density), or fully dense but at the expense of the nanophase microstructure.
Virtually all nanoparticulate materials are pyrophoric and must be handled and shipped as hazardous materials. Materials that are relatively stable as micrometer-sized powders can become dangerously explosive when in nanopowder form. Even when the powders do not react violently they may still pick up excessive oxygen, which usually makes their properties less desirable.
The cost of nanoscale powders is presently in the hundreds of dollars per kilogram range. While substantial reductions in cost are anticipated as nanotechnology develops, nanopowders will always be more expensive to produce than micrometer sized powders and entail much higher shipping and handling costs.
The production rate capabilities of any specific nanopowder production process and the stringent material specifications such as the primary particle size, size distribution, purity and extent of aggregation, are of paramount importance in determining the cost of the nanopowders. In the end powder cost which will ultimately be the decisive factor in determining whether nanomaterial-based commercial applications can be economically competitive.
In short, although there are numerous methods for producing nanopowders, most are not practical from a commercial perspective.
The powders must not only be of the desired size and morphology but also stable in air so that they can be handled and processed without excessive oxygen contamination or safety risks. Methods to avoid contamination and aggregation should be consistent with conventional industrial practices of the powder processing industry. For example, it would be impractical to require that nanopowders be continuously handled and processed in ultrahigh vacuum. Also the need to eliminate impurities, contaminants or aggregates can dramatically increase powder cost. For instance, salt encapsulation, used to protect nanoparticles produced by the sodium/halide flame and encapsulation (SFE) technique, imperatively requires that the salt be removed during subsequent processing using water, ammonia, an appropriate solvent or even vacuum sublimation at 700xc2x0 C.
In accordance with the present invention the problems of the prior art are substantially overcome by providing an economic process to generate optimally-sized nanopowders substantially free of aggregates and contamination, while reducing or eliminating the risks associated with their inherent pyrophoricity, and integrating said process in subsequent consolidation techniques for mass-production of dimensionally accurate nanostructures for commercial use.
It is a primary object of this invention to provide an integrated method for the fabrication of nanoparticulate materials free from aggregates and contamination.
It is another object of this invention to provide an integrated method for the fabrication of fine-grained nanostructures, substantially free from contamination and impurities. The fine-grained nanostructures are produced by first shaping green parts from an optimized dispersion of said aggregate and contamination-free nanoparticulates in a thermoplastic binder. All process steps, from dispersing the nanoparticulates into the organic binder through removal of the organic binder from the green parts to sintering of the resulting binder-free performs are performed contiguously and under protective atmosphere. The fine grain microstructures are achieved by sintering at the lowest possible temperature. At no time during this manufacturing process are the nanoparticulates or green parts exposed to temperatures which would promote excessive grain growth.
It is a particular object of this invention to provide a manufacturing process for nanostructures that are substantially sodium-free. This is a critical requirement for many applications in the microelectronic and semiconductor industry.
It is yet another object of this invention to provide a manufacturing process for nanostructures with improved dimensional accuracy.
It is still another object of this invention to provide an economic manufacturing process for nanostructures which lends itself easily to automation and mass-production and makes use of well-known prior art techniques such as casting, machining, molding, sintering, etc. It is therefore also an object of this invention is to provide a manufacturing method for nanostructures which is easily accessible to the nanufacturing industry instead of being restricted to specialized industries, laboratories and academic establishments. Hence, through this invention the world of nanotechnology will be opened to a wider number of practical users.
Still another object of this invention is to provide a method to optimize the selection and use of surfactants for nanoparticulate materials.
Also an object of this invention is to provide a method for controlling aggregation of nanoparticulate materials.
It is a further object of this invention to provide a method to optimize the dispersion of nanoparticulate materials in a thermoplastic organic matrix or binder.
An additional object of this invention is to provide a method to control the pyrophoricity inherent in nanoparticulate materials.
Still another object of this invention is to provide a method to fabricate nanostructures without the cost and material limitations inherent to the prior art. Through the use this invention nanostructures can be produced from a virtually unlimited number of material compositions.

Method for making articles from nanoparticulate materials


In a mobile communication system, the tracking of synchronization is conducted in a stable state even in a multipath environment. A delay profile detector calculates a delay profile a(n) using a despread signal for each processing unit n. A delay profile averaging unit averages a(n) to produce Ave(|a(n)|2). A data symbol detector conducts rake combining of the despread signal using a(n) and Ave(|a(n)|2). According to a(n) and Ave(|a(n)|2, a weighting function unit calculates a representative value representing delay waves. A loop filter generates a control signal in response to the representative value. A clock controller controls a spread code generator according to the control signal.

1. Field of the Invention
The present invention relates to a mobile communication system, and in particular, to a receiver, a mobile terminal, a base station, and a synchronization control method for use therewith.
2. Description of the Related Art
A code division multiple access (CDMA) scheme is a scheme in which a plurality of communication channels are multiplexed and are used for multiple accesses using a spectrum spreading code and hence has attracted attentions as a scheme to remarkably improve efficiency of frequency utilization. In a system using the CDMA, a transmission side multiplexes signals on channels necessary for communication such as a perch channel, a common control channel, a dedicated control channel, and a dedicated traffic channel by conducting a spectrum spreading modulation respectively with different spreading codes for the channels and transmits spread signals. On receiving the spread signals, a reception side despreads the signals with the spreading code used on the transmission side to demodulate a signal on a desired channel among the multiplexed signals. The signals modulated in the spectrum spreading modulation on the transmission side can be demodulated on the reception side only when both sides use the same spreading code and the same code phase. Therefore, an operation to establish synchronization and an operation to conduct tracking of synchronization on the reception side are regarded as essentially important techniques to implement the CDMA system. In the description, xe2x80x9csynchronization establishing operationxe2x80x9d indicates detection of a code phase of a spreading code used on the transmission side and xe2x80x9ctracking of synchronizationxe2x80x9d means keeping a code phase established.
In a phase to establish synchronization, a mobile terminal conducts a search for perch channels which the base stations around the terminal transmit. The perch channel includes information of a spreading code used by the base station and information necessary for power control to transmit them to the mobile terminal. The perch channel is almost continuously used by all base stations to send signals. A concrete method of establishing synchronization has been described in pages 57 to 63 of xe2x80x9cFast Cell Search Algorithm using Long Code Masking in DS-CDMA Asynchronous Cellular Systemxe2x80x9d written by Kenichi Higuchi, Kyoei Sawa, and Bunkoh Adachi in IEICE Technical Report RCS96-122, 1997-01.
The reason why the synchronization establishing and the tracking of synchronization are regarded as important is difficulty in the implementation of these operations as follows. In an actual propagation route, a propagation delay occurs in proportion to length of the route. Therefore, the code phase of the spreading code used on the reception side must be set to a value obtained by adding a phase shift associated with the propagation delay to the code phase on the transmission side. Furthermore, since the radio wave reflects at many places to arrive at the reception side through various paths, there appear a plurality of delayed waves. This phenomenon is generally called xe2x80x9cmultipathxe2x80x9d. Since the multipath brings about a plurality of received signal components having different phases on the reception side, the operation to establish synchronization and the synchronization tracking become difficult.
In the CDMA communication system, a rake receiving technique is employed to cope with the multipath. In the rake receiving technique, the delayed waves are separately demodulated with code phases corresponding to respective delay time of the waves, and resultant signals are combined with each other to obtain the diversity effect and a combined gain. To conduct the rake reception, it is required to simultaneously despread the received signal components having different phases. A technique of the prior art to implement the operation above is an invention of a matched filter described in JP-A-9-321664 entitled xe2x80x9cSpread Spectrum, Rake Receiver Using Time Window Control Loopxe2x80x9d. In the invention, despreading of a plurality of signals is simultaneously carried out with a plurality of spreading codes which are shifted by a fixed phase interval. In the matched filter, the despreading is accomplished in a predetermined phase range beginning at a code phase beforehand set. A time width corresponding to the predetermined phase range will be referred to as xe2x80x9ctime windowxe2x80x9d of the matched filter herebelow.
FIG. 14 shows a configuration diagram of a spread spectrum receiver of the related art. According to the related art, for a signal received by a radio frequency (RF) receiver 902, despread results corresponding to a plurality of code phases detected by matched filters 903 and 904 are inputted to an envelope detector 906 and a differential detector 905. For an output from the envelope detector 906, a maximum ratio combining controller 907 determines intensity of the despread results. According to the intensity of reception, signals detected by the differential detector 905 are combined with each other in a rake combining unit 910 to thereby achieve the rake reception. On the other hand, according to a result outputted from the envelope detector 906, a time window controller 908 and a sync tracking unit 909 control a time window location of the matched filters 903 and 904 such that a maximum peak position of an envelope aligns at a time window center location of the matched filters 903 and 904. Using an output from rake combining unit 910, a data reproducing unit 911 reproduces data.
In the related art, when there exist a plurality of delayed waves and there appear a plurality of correlation values corresponding to the respective waves, synchronization is aligned to one of the delayed waves which has a largest correlation value. Therefore, it can be expected in the related art that the tracking of synchronization is appropriately conducted only when a delayed wave having dominant intensity exists in a stable state among the delayed waves. However, in an actual environment, for example, in an urban environment, there exist many delayed waves and the respective delayed waves are not clearly different from each other in intensity in many cases. Moreover, fading is caused by movement of the mobile terminal and the respective delay waves strongly change in intensity depending on cases. As a result, the delayed wave having the largest correlation value frequently changes. Consequently, it is difficult in the related art to specify an appropriate code phase to be used for the tracking of synchronization.
In such an environment, received power is dispersed to the respective delayed waves and hence power per delayed wave is lowered. When either one of the delayed waves (paths) is selected for the tracking of synchronization, the overall received power can be only partly used for the tracking of synchronization and hence satisfactory stability cannot obtained.
It is therefore an object of the present invention to provide a synchronization control method, a receiver, a base station, and a mobile terminal which are particularly used in a CDMA mobile communication system and in which a state of out of synchronism is minimized and hence radio waves can be received in a stable state.
Another object of the present invention is that the tracking of synchronization is conducted in a stable state even in an environment such as an urban environment including a multipath and resultantly reduces the probability of call disconnection during a speech.
Further another object of the present invention is that a high-speed acquisition is conducted in an initial acquisition of synchronization and jitter due to noise is kept minimized after completion of the acquisition to stabilize the tracking of synchronization.
Still another object of the present invention is to minimize a period of time from when a terminal is powered to when the terminal is available for a speech and to reduce deterioration of speech quality due to phase jitter.
To solve the problem above in accordance with the present invention, the time window location of the matched filter is not aligned with a single path. Namely, a control operation is accomplished such that the time window location of the matched filter is aligned with a representative value which represents code phases corresponding to a plurality of paths for which valid correlational values have been detected and which represents spreading code phases of a plurality of paths obtained according to the respective correlational values. As the representative value, it is favorable to employ, for example, a center of path power.
In accordance with a first aspect of the present invention, there is provided a synchronization control method, comprising the steps of obtaining, according to a correlation between a received spread spectrum signal and an inputted spreading code, a delay profile including as elements thereof respective correlation values of a plurality of code phases, conducting a rake combining of despread signals according to the obtained delay profile and producing a decoded signal, calculating a representative value representing spreading code phases of a plurality of paths according to a plurality of correlation values and code phases thereof obtained from the delay profile obtained, and conducting a control operation for a tracking of synchronization between the received signal and the spreading code according to the calculated representative value.
In accordance with a second aspect of the present invention, there is provided a receiver including an input unit for producing a despread signal according to a correlation between a received spread spectrum signal and an inputted spreading code, a delay profile detector for producing a delay profile for the despread signal from the input unit, a data symbol demodulator for conducting a rake combining, according to the delay profile produced from the profile detector, for the despread signal from the input unit and producing a decoded signal; a representative value calculating unit for calculating, according to the delay profile produced from the profile detector, a representative value representing spreading code phases of a plurality of paths using a plurality of correlation values and code phases corresponded thereto, and a clock control unit for achieving a control operation to conduct a tracking of synchronization, according to the representative value from the representative value calculating unit, between the received signal inputted to the input unit and the spreading code.
In accordance with a third aspect of the present invention, there is provided a base station and a mobile terminal each including the receiver described above.

Mobile terminal, a base station, and a synchronization control method


The present invention provides, among other things, new processes for separating and purifying C4 fractions from a crude C4 stream. Compared to prior methods, the processes of the present invention simplify the C4 separation processes, afford more possible configurations for separation and purification, and are more cost effective. The processes and systems provided herein can be used as part of a cost-effective and efficient method for synthesizing methyl tertiary-butyl ether.

Steam cracking hydrocarbons produces by-product fractions containing carbon compounds of various lengths. One valuable fraction is the C4 fraction, which typically contains linear C4 molecules (e.g., butane, 1-butene, 1,2-butadiene, and 1,3-butadiene), non-linear C4 molecules (e.g., isobutane and isobutene), and impurities. These impurities can include, for example, acetylinic impurities (e.g., vinylacetylene, methylacetylene) as well as residual hydrocarbons with five or more carbon atoms (sometimes referred to as "heavies"). When the C4 components are separated and purified, they find use as starting materials in the manufacture of a variety of petrochemical products. For example, isobutene that is obtained by purification of a crude C4 stream can be reacted with methanol to produce methyl tert-butyl ether (MTBE), an anti-knocking additive that is commonly added to gasoline.
Current methods employed to separate C4 fractions from a crude C4 stream demand significant capital investment. Therefore, it would be useful to have improved, more cost-effective processes for separating crude C4 streams into useful and purified C4 fractions.

Methods and systems for separating C4 crude streams


A buffer composition, method and kit for hybridizing microarrays of nucleic acids bound to an adsorbed polymer surface of a siliceous substrate provide an envelope of conditions to hybridize nucleic acid targets, while preserving theintactness of the adsorbed polymer surface of the array. The buffer composition comprises a non-chelating buffering agent, a pH within a range of pH 6.4 and 7.5, a monovalent cation having a monovalent cation concentration that ranges from about 0.01 M to about 2.0 M, and optionally relatively lower concentrations of a chelating agent and an ionic surfactant. The total cation concentration of the buffer composition ranges from about 0.02 M to about 2.0 M. The method comprises incubating the targets with the microarray in the buffer composition at a temperature between about 55xc2x0 C. and 70xc2x0 C.

This invention relates to biological assays. In particular, the invention is directed to materials and methods of hybridizing microarrays of nucleic acid molecules for analytical, therapeutic and diagnostic purposes.
Microarrays of DNA or RNA polynucleotides or oligonucleotides are state-of-the-art biological tools used in the investigation and evaluation of genes for analytical, diagnostic, and therapeutic purposes. Microarrays typically comprise a plurality of oligomers, synthesized or deposited on a glass support or substrate in an array pattern. The support-bound oligomers are called xe2x80x9cprobesxe2x80x9d and function to bind or hybridize with a sample of DNA or RNA material under test, called a xe2x80x9ctargetxe2x80x9d in hybridization experiments. However, some investigators bind the target sample under test to the microarray substrate and put the oligomer probes in solution for hybridization. Moreover, some investigators use the reverse definition, referring to the surface-bound oligonucleotides as targets and the solution sample of nucleic acids as probes. Either of the xe2x80x9ctargetsxe2x80x9d or xe2x80x9cprobesxe2x80x9d may be the one that is to be evaluated by the other (thus, either one could be an unknown mixture of polynucleotides to be evaluated by binding with the other). All of these iterations are within the scope of this discussion herein. In use, the microarray surface is contacted with one or more targets under conditions that promote specific, high-affinity binding of the target to one or more of the probes. The targets are typically labeled with an optically detectable label, such as a fluorescent tag, so that the hybridized targets and probes are detectable with scanning equipment. DNA array technology offers the potential of using a multitude (hundreds of thousands) of different oligonucleotides to analyze changing mRNA populations.
There are numerous types of substrates used in hybridization assays. Common substrates or supports used for microarray assays are siliceous substrates, such as glass. The surface of the substrates are typically treated or derivatized to facilitate binding of the probes to the substrate. For in situ synthesis of probes, the first monomers of the oligomer probe sequences are attached to the substrate surface that is derivatized with a silane or other compounds known in the art to facilitate the bonding of the first monomers. Subsequent monomers are added directly to the monomers of the growing oligomer chain. For deposition of presynthesized or whole probes, such as cDNA probes, the probe is attached to a polymer adsorbed or coated on the surface of the substrate to facilitate bonding. The adsorbed polymer is coated and dried on the substrate surface. The substrate surface derivatizations enable and facilitate the attachment of nucleic acids to the surface of microarray substrates for the manufacture of the microarrays. Surface treatments or derivatization techniques, including those mentioned above, are well known in the art.
Microarrays of oligomer probes, such as oligonucleotides or polynucleotides, are hybridized using conventional methods and hybridization solutions. J. Sambrook, E. F. Fritsch, T. Maniatis, Molecular Cloning: A Laboratory Manual, Cold Spring Harbor Laboratory Press, Cold Spring Harbor, Ed. 2nd, 1989, vol. 1-3, incorporated herein by reference, describe the considerations and conditions for hybridization of oligonucleotide probes. Probe length, hybridization temperature, as well as other factors that are well known in the art affect hybridization conditions. Typically, hybridizations using synthetic oligomers are usually carried out under conditions that are 5-10xc2x0 C. below the calculated melting temperature Tm of a perfect hybrid to minimize mismatched or non-Watson/Crick base pairing between the probe and target, and maximize the rate at which Watson/Crick base pairs form. Other factors influencing the rate of hybrid formation include the salt concentration, the presence of surfactants, solvents or co-solvents, the concentration of nucleic acid in solution, the length of hybridization, and the degree and method of agitation.
The hybridization solution typically comprises a salt (monovalent cation), either SSPE or SSC buffer that provides buffering capacity between pH 6.8-8.5 (more typically between pH 7.0-7.5), a divalent cation chelating agent (e.g. ethylenediaminetetraacetic acid, EDTA), and agents for blocking non-specific binding of targets to the array surface (surfactants, proteins and/or carrier DNA from an organism unrelated to the experiment at hand). More specifically, a typical hybridization solution contains 6xc3x97SSPE (0.9 M NaCl, 60 mM sodium phosphate (pH 7.4); 6 mM EDTA); or 6xc3x97SSC (0.9 M NaCl, 90 mM sodium citrate (pH 7.0)), 0.5% w/v sodium dodecyl sulfate (SDS); 100 xcexcg/ml denatured, fragmented salmon sperm DNA; and 0.1% nonfat dried milk.
The microarray is hybridized for a period of time ranging from about 2 hours to about 2 days, depending on the make-up of the probes (i.e., probe length and diversity of probe composition) and the complexity of the target, for example, at a controlled temperature, which typically ranges from 20xc2x0 C. to 70xc2x0 C., depending on the melting temperature Tm, as discussed above. Low temperature hybridizations are performed at about 20xc2x0 C. to about 50xc2x0 C. (typically about 37-45xc2x0 C.). High temperature hybridizations are performed at or around 55xc2x0 C. to about 70xc2x0 C. (typically 60xc2x0 C. to 65xc2x0 C.). However, for most nucleic acid microarrays, high temperature hybridizations are preferred in the art since the higher temperature maximizes the rate of Watson/Crick base pairing of nucleotides, while low temperature hybridizations typically maximize Watson/Crick base pairings by use of a co-solvent to lower the Tm. The typical time period for hybridization of a microarray is overnight or longer (i.e., anywhere from 8 hours to 24 hours) so as to hybridize the target. The array is then washed and dried and optically scanned to measure the degree of hybridization using conventional methods and equipment that are well known in the art.
A problem in the DNA microarray hybridization art is sporadic poor hybridization assay performance characterized by low-intensity or missing features on the microarray substrate, high backgrounds, and visually xe2x80x9cblotchyxe2x80x9d substrates. For microarrays containing DNA on adsorbed polymer substrate surfaces, this problem has been observed using conventional hybridization conditions, such as using a solution comprising 20xc3x97SSC (3.0 M NaCl, 300 mM Sodium Citrate (pH 7.0), 10% SDS) at high hybridization temperature of about 65xc2x0 C. and within conventional hybridization times of about 6 hrs. to about 24 hours.
Thus, it would be advantageous to have materials, conditions and methods of hybridizing arrays of oligomers on siliceous substrates that have been treated or coated with a surface adsorbed polymer in biological assays at the preferred higher hybridization temperature range and longer hybridization times without affecting the hybridization assay performance.
The present invention provides a buffer composition and method for hybridizing nucleic acid microarrays with other nucleic acid materials used in high throughput analytical, therapeutic, and diagnostic applications. The method uses an envelope of hybridization conditions for performing assays at high hybridization temperatures for long periods of time. The hybridization conditions of the method advantageously are compatible with siliceous substrates having adsorbed polymer surfaces. The buffer composition and method of the present invention work particularly well on adsorbed polycationic polymer coated siliceous surfaces. The envelope of conditions addresses solution pH and buffer type, salt composition, surfactant composition, temperature and time. The present invention allows sensitive, selective detection of nucleic acid targets, while preserving the intactness of the adsorbed polymer siliceous surface. The buffer composition and method of the invention overcome the problems found in the art by reducing delamination of the surface polymer and reducing residues when performing assays on adsorbed polymer siliceous substrate surfaces at high hybridization temperatures between about 55xc2x0 C. and 70xc2x0 C. for time periods used to hybridize a target material. The buffer composition and method of the present invention provide optimized hybridization assay performance by maintaining the integrity of the adsorbed polymer surface of the siliceous substrates.
In one aspect of the invention, a buffer composition for hybridization assays of arrays of oligonucleotides bound to an adsorbed polymer substrate surface with another nucleic acid material is provided. The buffer composition comprises a pH in a range of pH 6.4 to 7.5, a monovalent cation having a monovalent cation concentration ranging from about 0.01 M to 2.0 M, and a non-chelating buffering agent that maintains the pH within the pH range. The buffer composition may optionally further comprise relatively lower concentrations of an ionic surfactant and/or a chelating agent. The buffer composition has a total cation concentration ranging from about 0.02 M to about 2.0 M, accounting for all components in the buffer solution. In one embodiment, the buffer composition further comprises nucleic acids in solution and is used in a hybridization assay of a nucleic acid material under test that is attached to an adsorbed polymer surface of a siliceous substrate.
In another aspect of the invention, a method of hybridizing a microarray of oligonucleotides on an adsorbed polymer surface of a siliceous substrate with another nucleic acid material is provided. The method of hybridizing comprises the step of incubating the nucleic acid material with the microarray of oligonucleotides on the adsorbed polymer surface in a hybridization solution at a hybridization temperature ranging from about 55xc2x0 C. to about 70xc2x0 C. so as to hybridize the nucleic acid material, wherein the hybridization solution comprises a buffer composition that comprises a pH within a range of pH 6.4 and 7.5, a non-chelating buffering agent, and a monovalent cation in a monovalent cation concentration ranging from about 0.01 M to about 2.0 M. The buffer composition may optionally further comprise relatively lower concentrations of a chelating agent and/or an ionic surfactant.
In still another aspect of the invention, a buffer kit for performing hybridization assays on siliceous substrates having an adsorbed polymer on the substrate surface is provided. In one embodiment, the kit comprises the buffer composition of the present invention that comprises a non-chelating buffering agent, a pH within a range of pH 6.4 and 7.5 and a total cation concentration ranging from about 0.02 M to about 2.0 M. In another embodiment, the kit comprises a components list for the buffer composition of the present invention. The components list comprises the components of the buffer composition of the present invention described above. Optional instructions may be included in the kits. The optional instructions comprise the method of the present invention described above, or instructions for using the buffer composition in a hybridization assay of a nucleic acid material with a siliceous substrate that has an adsorbed polymer surface for attaching to nucleic acids. In still another embodiment, the kit may further a nucleic acid sample for use as a hybridization assay control. Still further, the buffer composition in the kit may further comprise nucleic acids in solution, or the kit may further comprise a microarray of nucleic acids attached to an adsorbed polymer surface of a siliceous array substrate for use with a nucleic acid material in a hybridization assay.
The buffer composition, method and kit of the present invention overcome the problems in the art by reducing degradation of the adsorbed polymer surface of the microarray substrate and any further etching of the substrate, both of which impact the hybridization results between nucleic acid probes and target materials at high temperatures. Further, the present invention does not affect the signal intensities of the fluorescent labeling system used in conventional hybridization assays. The hybridization conditions and methods of the present invention are particularly useful in DNA or RNA microarray assays performed at high temperatures, i.e., above about 55xc2x0 C., and for longer hybridization times, i.e., equal to or greater than about 6 hours, where conventional buffer compositions, including but not limited to SSC and SSPE react with the conventional adsorbed polymer surface of siliceous substrates, and affect hybridization results.

Buffer composition and method for hybridization of microarrays on adsorbed polymer siliceous surfaces


A translation corpus creation method of the present disclosure includes generating plural paraphrasing candidate sentences for a first original sentence in a first language by paraphrasing one or plural fragments among plural fragments included in the first original sentence into other expressions in the first language by a paraphrasing candidate sentence generation unit, identifying one or plural paraphrasing candidate sentences in the same meaning as the meaning of the first original sentence from the plural paraphrasing candidate sentences as one or plural paraphrasing sentences by a paraphrasing sentence identification unit, and generating a new set of sentences by setting the one or plural identified paraphrasing sentences and a second original sentence translated from the first original sentence as a set of sentences to create a translation corpus with the generated and new set of sentences by a translation corpus creation unit.

1. Technical Field
The present disclosure relates to a translation corpus creation method that creates a translation corpus which accumulates pairs of sentences formed with mutually different languages, a translation corpus creation device, a recording medium storing a translation corpus creation program, and a machine translation system that uses the translation corpus creation device.
2. Description of the Related Art
In recent years, machine translation has been studied and developed in which a sentence in a first language is translated into a sentence in a second language that is different from the first language. For example, various techniques have been suggested such as Japanese Patent No. 3919720, Japanese Unexamined Patent Application Publication No. 2002-278963, Japanese Unexamined Patent Application Publication No. 2006-190072, Japanese Unexamined Patent Application Publication No. 2015-118498, "Generating Targeted Paraphrases for Improved Translation", Nitin Madnani, Educational Testing Service, ACM, 2013, and "Distributional Phrasal Paraphrase Generation for Statistical Machine Translation", Yuval Marton, University of Maryland, Columbia University, ACM, 2013.

PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO., LTD.


A system and method for an access code issuer to receive an on-line application including certain personal information from a user of a computer network such as the Internet, to independently operatively connect to a database and obtain or verify demographic and additional personal information regarding the user, and issue an access code to the user. The user enters this access code when accessing various nodes or websites of a plurality of affiliated content providers. The content providers obtain or verify the user's demographics by operatively connecting to the access code issuer, thereby obtaining or verifying the demographics of the visitor to its site without requiring the visitor to enter his or her demographic information or to independently provide proof thereof to the content provider. The content provider can then customize the presentation and advertising on its site according to the demographics of the user, and/or can restrict access to its site or portions thereof based on demographics or other information regarding the user. Authentication is provided using a portion of a social security number.

1. Field of the Invention
The present invention relates to communications systems and authentication. More particularly, the present invention relates to a system and method for demographically selective distribution of information and entertainment and for user authentication.
2. Description of the Related Art
The Internet has rapidly become a major vehicle for information dispersal, education, entertainment, commerce, and other forms of communication and interaction. A number of websites including portal sites present news, entertainment, shopping opportunities, and other content, with revenue often derived from banner advertising. The advertising presented on such sites i.e., usually broadcast indiscriminately to whomever visits the site, and thus is often of little interest to the web site visitor, and indeed, is often considered to be a nuisance. On the other hand, it is difficult for a variety of reasons to induce people to enter personal information about themselves so that advertising can be customized and targeted.
The Internet also gives rise to jurisdictional complications. Website operators may wish to offer products and services, but at the same time wish to avoid conducting business with persons in certain foreign countries or other jurisdictions, so as to avoid exposing themselves to personal jurisdiction in foreign and unfamiliar courts.
Website operators may wish to restrict the persons who may view and interact with content of their web sites to persons having certain demographic characteristics. Web site operators may also wish to prevent visitors from entering personal information unless those visitors are of specified minimum age, in order to comply with child on-line privacy protection laws. Web site operators may also wish to restrict access to adult entertainment content to those persons eighteen years or older in order to comply with legal restrictions. A number of adult verification services exist for providing personal identification numbers which can be used to access adult entertainment sites. However, those services are believed to rely upon the existence of a credit card in order to determine whether someone qualifies for access to such sites. Because some credit card issuers issue credit cards to minors, those services do not actually verify a person's age.
Various attempts have also been made to prevent children from accessing inappropriate content, particularly from Internet terminals installed in public libraries. Filtering software is available, but such software is prone to filtering out either too much or too little content, or both at the same time. At least one court has struck down as unconstitutional a county policy requiring libraries to install filtering software.
Chat groups and other forums exist on the Internet for the interchange of ideas between and among website visitors. Like any other communication, sometimes it is desirable to restrict discussions to only certain persons or certain groups of people.
Another issue that faces users of electronic systems, such as the Internet, is user authentication. For both the protection of the user and merchants and other entities engaging in transactions or communications with the user, it is often necessary to authenticate the user, meaning to verify that the user is the individual that the user purports to be.
One of the problems and difficulties with user identification has been the proliferation of identification information about users. This has made it easier for the identity of a user to be misappropriated.
For this very same reason, users are often hesitant to provide the most confidential classes of identifying information, such as their social security numbers.

Authentication using portion of social security number


A vehicle brakes traction control system and method of operation, for a vehicle having a drive axle with a differential operable between wheels at the two ends of the axle, and brakes for each respective wheel operable by a brake controller. The traction control system includes wheel speed sensors sensing the rotational speed of the wheels, an engine torque demand sensor and an engine torque output monitor. The brake system controller receives signals from the wheel speed sensors, the engine torque demand sensor and the engine torque output monitor to apply the brakes to equalize the rotational speed of the wheels if the engine torque output is less than a desired torque output for a given torque demand.

This invention relates to traction control systems used on motor vehicles and which is an enhancement to brakes only traction control systems.
Brakes traction control systems (BTCS) are typically used when driving off-road. BTCS in its most basic form acts as an electronically controlled variable slip differential lock for a drive axle on a vehicle in which torque is applied to wheels at opposite end of the axle via a conventional differential unit. The BTCS monitors the rotational speed of the wheels via wheel speed sensors and each wheel is provided with an independent braking actuator. The information from the sensors is fed to a brake system controller where the information is processed and the brakes to the wheels operated with the aim of improving traction.
If the vehicle is being driven on a non-homogenous surface and sufficient driving torque is applied it is possible for a wheel having a lower surface adhesion to loose grip and spin. In this situation, this wheel will require a relatively low torque, as compared with the other wheel, to cause it to xe2x80x9cover spinxe2x80x9d. If the axle has a conventional differential, then the differential will permit only this same low torque to be transmitted to the non-spinning wheel. This level of torque may not be sufficient to maintain vehicle movement. The BTCS causes the brake actuator associated with the spinning wheel to apply the associated brake and increase its torque output in order to transfer torque across the differential to the non-spinning wheel. The non-spinning wheel then gains sufficient torque to achieve vehicle movement and its speed of rotation increases. The BTCS controls both wheels until their rotational speeds equalise.
A problem with this type of BTCS is that if the vehicle does not accelerate quickly, the brakes when applied to the spinning wheel may cause engine stall. Some BTCS are programmed to recognise engine stall and implement strategies to prevent this happening. This may leave the vehicle immobilised with the engine held in low revs and unable to supply the necessary torque to move the vehicle. Such a situation may be experienced with vehicles having small engines when driven off-road.
According to the present invention there is provided a vehicle brakes traction control system for a vehicle having at least one drive axle with a differential operable between wheels at the two ends of the axle, and brakes for each respective wheel operable by a brake controller, the traction control system including wheel speed sensors which sense the rotational speed of said wheels, an engine torque demand sensor and an engine torque output monitor, the brake system controller receiving signals from said sensors and monitor and being operable to apply the brakes to equalise the rotational speed of said wheels when the engine torque output is less than a desired torque output for a given torque demand.
The torque demand sensor may be a throttle opening sensor such as an accelerator pedal position sensor, and the torque output monitor may include a torque output map.
The engine speed at which maximum torque output is targeted may be altered in relation to the rate of change of torque demand in particular so that the rate of torque build up at the wheels is proportional to the rate of change of torque demand. When the control system is for use in a vehicle having an engine management system (EMS) with an engine map stored therein which includes information relating to the engine speed at which the maximum torque is available for a given torque demand e.g. throttle opening, the brake system controller operates the vehicle brakes only when excess rotational speed is detected for one of said wheels and when in receipt of a signal from the EMS indicating that the engine speed is above that required for maximum torque output. Such a system is self tuning for any EMS.
Alternatively, the brakes controller has an engine map stored therein which includes information relating to the engine speed at which the maximum torque is available for given throttle openings, wherein the brake system controller operates the vehicle brakes when excess rotational speed is detected for one of said wheels and when the engine speed is above that required for maximum torque output.
The engine torque output may be measured as a function of rotational speed of the engine.
Also according to the present invention there is provided a method of operation of a vehicle brakes traction control system for a vehicle having at least one drive axle with a differential operable between wheels at the two ends of the axle, wherein the system is operable to apply the vehicle brakes to equalise the rotational speed of said wheels only when the engine torque output is less than a desired torque output for a given engine torque demand.