A method for embedded failure detection includes embedding radio frequency identification (RFID) tags at varying depths within a composite material including a polymer, an epoxy or an aggregate bonded with a fluid. Each RFID tag is attached with an insulated wire loop and a sensor and configured to communicate tag identification and resistance on each insulated wire loop upon being energized by an RFID reader. The sensor may be for temperature, moisture, humidity, pressure, light, or acceleration. The RFID tags are read with an RFID reader after initial curing of the composite material for reference information. The RFID reader reads the RFID tags after a particular time period for current information. The current information is compared to the reference information. It is determined whether a change information has occurred for any of the RFID tags to detect a possible failure of the composite material.

Most of critical city (and corporate) infrastructure relies on concrete, cement, etc., yet this infrastructure is aging and fragile, and thus a potential threat to both economy and life. Any structure using concrete is subject to material failure, such as buildings, bridges, etc. This is an issue regardless of the cause: earthquake, fire, overload, impact, chemical attack (intentional or unintentional), etc., or simply just due to age. Given the opaque nature of concrete, evaluating the structural soundness of the concrete, or assessing for possible damage, is an expensive, complex, time-consuming effort, yet is required more and more due to the aging of critical infrastructure.

Embedded failure detection in composite material


A multi-block manifold facilitates assembly of the manifold in a fluid handling apparatus during manufacture and disassembly and removal of a secondary manifold block of the manifold during service without disconnecting external tubes and flow control devices from the manifold. The external tubes are isolated and integral to a primary manifold block of the manifold which is permanently mounted in the apparatus and the flow control devices are integral to the secondary manifold block which is quickly, releasably secured to the primary manifold block in the apparatus.

Methods and apparatus are known for construction of manifolds to direct and control fluids in a complex flow circuit. Typically, flow paths are machined in a metal block in such a configuration as to direct fluid in a logical manner between several control devices. A metal block accomplishes the same paths as could be done with several fittings and interconnecting tubes between the various control devices.
Present manifold designs, for example that disclosed in U.S. Pat. No. 5,094,087, have an inherent problem in that they can be very difficult to assemble into equipment during initial manufacture and, more importantly, difficult and time consuming for repair technicians to diagnose and correct problems in the field. In addition to component malfunctions, debris which may enter the pathways in the manifold or ports of control devices will cause an operational malfunction. The manifold typically cannot be cleared using conventional means and must be partially disassembled or replaced in its entirety. The present manifold design necessitates uncoupling external tubes, devices and wiring harnesses. There is the possibility of wiring connections being made incorrectly during reassembling. Also, special tools are often required and space limitations make reassembly difficult.
The present invention is directed to an improved fluid handling apparatus having a complex flow circuit, a manifold therefor and a method of making the same, which solve these problems through a multi-block manifold design. The manifold comprises a primary manifold block mountable, e.g. permanently mounted, in the fluid handling apparatus, and a secondary manifold block mountable on the primary manifold block. At least one quick-connect connector is provided for quickly, releasably securing the secondary manifold block on the primary manifold block. A plurality of fluid flow paths are provided in the primary and secondary manifold blocks. A plurality of flow control devices are provided on the manifold for controlling fluid flow in the fluid flow paths of the manifold and complex flow circuit of the apparatus. A plurality of manifold ports with connections for external tubes are provided to convey fluid to and from the fluid flow paths in the manifold. According to the invention, the plurality of manifold ports with connections for external tubes are isolated and integral to the primary manifold block and the plurality of flow control devices are integral to the secondary manifold block. This facilitates assembly of the manifold in the apparatus during manufacture, and disassembly and removal of the secondary manifold block from the apparatus during service without disconnecting external tubes and flow control devices from the manifold. In the event of a malfunction within the manifold, the secondary manifold block can be quickly disconnected and removed from the primary manifold block and replaced with a new one and the defective block returned to the factory for diagnosis and repair.
A further feature of the invention is that the plurality of flow control devices of the manifold include electrically operated flow control devices and the manifold includes a wiring harness integral to the secondary manifold block. The wiring harness has wires electrically connected to the electrically operated flow control devices and connected to a common electrical plug. Means are provided on the primary and secondary manifold blocks for aligning the blocks with respect to each other during mounting of the secondary manifold block on the primary manifold block. The means for aligning the blocks and the electrical plug of the wiring harness prevent assembly errors when the two blocks are connected.
The method of the invention for making a manifold for directing and controlling fluid in a complex flow circuit of a fluid handling apparatus, such as a refrigerant recycling machine, comprises providing a multi-block manifold according to the invention and installing the multi-block manifold in the fluid handling apparatus with the primary manifold block permanently mounted in the apparatus and the secondary manifold block quickly, releasably secured on the primary manifold block. The method further includes providing a wiring harness integral to the secondary manifold block with wires of the harness electrically connected to electrically operated flow control devices of the manifold on the secondary manifold block thereby facilitating the assembly of the manifold in the apparatus during manufacture and the disassembly and removal of the secondary manifold block during service without disconnecting external tubes and flow control devices from the manifold.
These and other features and advantages of the invention will become more apparent when taken with the following detailed description of an example embodiment of the invention which is illustrated in the accompanying drawings.

Fluid handling apparatus, manifold therefor and method of making same


A light emitting drive substrate, a manufacturing method of the light emitting drive substrate, a light emitting substrate and a display device. The light emitting drive substrate includes a first light-emitting subregion, a second light-emitting subregion, a periphery area, a first power supply wire and a second power supply wire. A resistance between the first end and the second end of the first power supply wire is equal to a resistance between the first end and the second end of the second power supply wire, and a wire length between the first end and the second end of the first power supply wire is not equal to a wire length between the first end and the second end of the second power supply wire.

With the continuous development of display technology, users have higher and higher requirements for the contrast ratio, brightness uniformity and screen-to-body ratio of the display device.
The liquid crystal display device includes a backlight module and a liquid crystal panel. The backlight module is arranged on the non-display side of the liquid crystal panel to provide a light source for the display operation of the display panel. The liquid crystal panel comprises a polarizer, an array substrate, an opposite substrate and a liquid crystal molecular layer filled between the above two substrates. The liquid crystal display device allows the liquid crystal molecules in the liquid crystal molecular layer to be rotated by forming an electric field between the array substrate and the opposite substrate, and the rotated liquid crystal molecules can cooperate with the polarizer to form a liquid crystal light valve. Because the liquid crystal molecular layer itself does not emit light, the liquid crystal display device needs to use backlight module to realize the display function. The contrast ratio, brightness uniformity and screen-to-body ratio of the liquid crystal display device are related to the structure and performance of backlight module.

Light emitting drive substrate and manufacturing method thereof, light emitting substrate and display device


A sewing machine includes a detection device that detects whether a feed distance by which the piece of work cloth is shifted by a feed dog in the back-and-forth or right-and-left direction has reached a predetermined distance, a counting device that counts a number of forward feed stitches and a number of backward feed stitches which are sewn when the piece of work cloth is shifted backward and forward, respectively, by the predetermined feed distance detected by the detection device or a number of leftward feed stitches and a number of rightward feed stitches which are sewn when the piece of work cloth is shifted leftward and rightward, respectively, by the predetermined feed distance, and a correction value setting device that sets a correction value to correct the feed distance based on a result of the counting of the number of stitches by the counting device.

The present disclosure generally relates to a sewing machine.
Conventionally, in an electronically-controlled sewing machine, a feed dog that feeds a piece of work cloth is driven by a pulse motor. The pulse motor is controlled based on feed data stored in the sewing machine, thereby feeding the piece of work cloth in a sewing direction. In such a feed mechanism, even when the pulse motor is precisely rotated by a predetermined number of rotations, an error may occur in feeding distance due to a mechanical error or the shape of a presser foot. Such an error in the feeding distance varies according to whether the piece of cloth is fed forward (normal feeding) and backward (reverse feeding), so that finished stitches may be influenced in some patterns. In order to solve this problem, Japanese Patent Application Laid-Open Publication No. Hei 4-73089 proposes an approach for intermittently correcting feed data by mounting a correction key to which a correction amount obtained through trial sewing is set. Japanese Patent Application Laid-Open Publication No. Hei 5-49772 proposes the determination of the type of a stitching pattern prior to correction and it is set such that the correction is not made for a specific pattern, such as a satin stitching, so that a disorder in the stitching may not occur at a corrected portion that would damage the appearance.
However, according to these conventional methods, a correction amount to be employed in correction will be decided by the user through trial sewing and will be determined manually. Determining the correction amount is therefore troublesome and takes a lot of time.


Disclosed is a method of treating a process stream from a process producing a non-biodegradable alkylene carbonate stream. The alkylene carbonate is hydrolyzed in a strong, aqueous, alkaline solution to form an aqueous alkaline solution of the corresponding alkylene glycol. This solution is then acidified to a pH of about 8 to 8.5. The acidified solution is aerated in activated sludge to reduce the biological oxugen demand (BOD) of the solution.

The alkylene carbonate effluents treated by the method of the invention are produced as the effluents of photolithographic processes. More specifically, they are impure alklyene carbonate solution, laden with both dissolved and suspended photoresist, and with other impurities.
Photolithographic processes in packaging are described in Microelectronics Packaging Handbook, Pub. Van Nostrand Reinhold, New York, 1989, Tummala et al, eds. on pages 898-903, in Principles of Electronic Packaging, McGraw-Hill Book Company, New York, 1989, Seraphim et al, eds. in Chapter 12, pages 372-393 and in Scientific Encyclopedia, 6th Ed., Vol. II, Pub. Van Nostrand Reinhold Company, New York, 1983, Considine et al, eds., pages 1877-1881, all of which are incorporated herein by reference for use as background.
Photolithography plays a critical role in the art of printed circuit packaging. Photolithography is used to define in a thin film of photoresist those regions either from which copper is to be selectively etched to subtractively form circuitization, or selectively plated to additively form circuitization.
There are two types of photoresist: negative and positive. A negative photoresist is polymerized by exposure, e.g., selective exposure to the particular actinic radiation to which it is sensitive for an adequate period of time. It is then subjected to its developer. The developer solubilizes the areas of the resist which have not been exposed to actinic radiation. The areas of negative photoresist which have been exposed to actinic radiation are hardened by cross-linking and made more resistant to developer, relative to the unexposed regions.
Positive acting resists behave oppositely. Actinic radiation renders the positive acting photoresist more soluble in the developer, and the exposed regions are removed preferentially by a dilute alkaline developer.
Positive acting photoresists are used extensively to fabricate silicon devices, and for subtractive circuitization of printed circuit boards. However, positive photoresists, which are readily developed by dilute aqueous alkaline solutions and stripped by more concentrated aqueous alkaline solutions, perform poorly in high caustic environments and high temperatures.
The negative resists, on the other hand, are used when the circuit lines are provided by additive plating of copper, in areas where copper is desired, i.e., electroless or electroless plus electroplating, rather than by etching of copper away from where it is not desired.
Negative acting photoresists are cross-linked by the action of actinic energy on photoactive agents that form the free radicals or ionic groups necessary to initiate and/or support polymerization. Depending on their composition, commercially available photoresists are sensitive to UV radiation, X-rays, E-beams and so forth. The radiation may be furnished to the resist through a pattern in a mask, such as an emulsion mask or chrome mask, by contact or projection, or a beam of radiation may be rastered.
Negative acting photoresists include an organic resin binder, a photoinitiator/photosensitizer and a reactive monomer. Optionally, negative acting photo-resists also include fillers, for example, organic or inorganic fillers, fire retardants, plasticizers, dyes, flexibilizers, thermal stabilizers and other additives to improve the processing characteristics of the package.
Typical negative photoresist compositions include from 40 to 70% by weight of binder, 10 to 40% by weight of monomer, and 0.5 to 15% by weight of photoinitiator, to total 100% based on the weight of all these components.
An example of such compositions is described in U.S. Pat. No. 4,326,010. (example 1).
In general negative-working resists are photopolymerizable materials of the type described in U.S. Pat. No. 3,469,982, U.S. Pat. No. 4,273,857 and U.S. Pat. No. 4,293,635 and the photocrosslinkable species of the type disclosed in U.S. Pat. No. 3,526,504.
Monomers which can be used either alone or in combination with others to form negative acting photoresists include: t-butyl acrylate, 1,5 pentanediol diacrylate, N,N-diethylaminoethyl acrylate, ethylene glycol diacrylate, 1,4-butanediol diacrylate, diethylene glycol diacrylate, hexamethylene glycol diacrylate, 1,3-propanediol diacrylate, decamethylene glycol diacrylate, decamethylene glycol dimethacrylate, 1,4-cyclohexanediol diacrylate, 2,2-dimethylolpropane diacrylate, glycerol diacrylate, tripropylene glycol diacrylate, glycerol triacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, polyoxyethylated trimethylolpropane triacrylate and trimethacrylate and similar compounds as disclosed in U.S. Pat. No. 3,380,831, 2,2-di-(p-hydroxyphenyl)-propane diacrylate, pentaerythritol tetraacrylate, 2,2-di(p-hydrohyphenyl)-propane dimethacrylate, triethylene glycol diacrylate, polyoxyethyl-2,2-di-(p-hydroxyphenyl)-propane dimethacrylate, di-(3-methacryloxy-2-hydroxypropyl) ether of bisphenol-A, di-(2-methacryloxyethyl) ether of bisphenol-A, di-(3-acryloxy-2-hydroxypropyl) ether of bisphenol-A, di-(2-acryloxyethyl) ether of bisphenol-A, di-(3-methacryloxy-2-hydroxypropyl) ether of tetrachloro-bisphenol-A, di-(2-methacryloxyethyl) ether of tetrachloro-bisphenol-A, di-(3-methacryloxy-2-hydroxypropyl) ether of tetrabromo-bisphenol-A, di-(2-methacryloxyethyl) ether of tetrabromo-bisphenol-A, di-(3-methacryloxy-2-hydroxypropyl) ether of 1,4-butanediol, di-(3-methacryloxy-2-hydroxypropyl) ether of diphenolic acid, triethylene glycol dimethacrylate, polyoxypropyltrimethylol propane triacrylate, ethylene glycol dimethacrylate, butylene glycol dimethacrylate, 1,3-propanediol dimethacrylate, 1,2,4-butanetriol trimethacrylate, 2,2,4-trimethyl-1,3-pentanediol dimethacrylate, pentaerythritol trimethacrylate, 1-phenyl ethylene-1,2-dimethacrylate, pentaerythritol tetramethacrylate, trimethylol propane trimethacrylate, 1,5-pentanediol dimethacrylate, diallyl fumarate, styrene, 1,4-benzenediol dimethacrylate, 1,4-diisopropenyl benzene, and 1,3,5-triisopropenyl benzene.
In addition to the monomers mentioned above, the photoresist material can also contain one or more free radical-initiated and polymerizable species with molecular weight of at least about 300. Monomers of this type are an alkylene or a polyalkylene glycol diacrylate and those described in U.S. Pat. No. 2,927,022.
Free radical initiators which can be activated by actinic radiation which are thermally inactive at and below 185 degrees Centigrade include the substituted or unsubstituted polynuclear quinones listed in the following: 9,10-anthraquinone, 1-chloroanthraquinone, 2-chloroanthraquinone, 2-methylanthraquinone, 2-tertbutylanthraquinone, octamethylanthraquinone, 1,4-naphthoquinone, 9,10-phenanthrequinone, 1,2-benzanthraquinone, 2,3-benzanthraquinone, 2-methyl-1,4-naphthone, 2,3-dichloronaphthoquinone, 1,4-dimethylanthraquinone, 2,3-dimethylanthraquinone, 2-phenylanthraquinone, 2,3-diphenylanthraquinone, 2,3-diphenylanthraquinone, sodium salt of anthraquinone alphasulfonic acid, 3-chloro-2-methylanthraquinone, retenequinone, 7,8,9,10-tetrahydronaphthacenequinone, and 1,2,3,4-tetrahydrobenz(a)anthracene-7,12-dione.
Other useful photoinitiators, of which some may be thermally active at temperatures lower than 85 degrees C., are described in U.S. Pat. No. 2,760,863.
Dyes of a photoreducible nature and other reducing agents are described in U.S. Pat. Nos. 2,850,445; 2,875,047; 3,097,096; 3,074,974; 3,097,097; and 3,145,104 as well as dyes of the phenazine, oxazine and quinone classes; Micheler's ketone, benzophenone, 2,4,5-triphenylimidazolyl dimers with hydrogen donors, and mixtures thereof as described in U.S. Pat. Nos. 3,427,161; 3,479,185 and 3,549,367 can be used as initiators. The cyclohexadienone compounds of U.S. Pat. No. 4,341,860 are also useful as initiators. In addition sensitizers described in U.S. Pat. No. 4,162,162 in combination with photoinitiators and photoinhibitors are useful.
Polymeric binders which can be used alone, or in combination with polymerizable monomers include the following: polyacrylate and alpha-alkyl polyacrylate esters, i.e. polymethyl methacrylate and polyethyl methacrylate; polyvinyl esters: i.e. polyvinyl acetate, polyvinyl acetate/acrylate, polyvinyl acetate/methacrylate and hydrolyzed polyvinyl acetate; ethylene/vinyl acetate copolymers; polystyrene polymers and copolymers, i.e. with maleic anhydride and esters; vinylidene chloride copolymers, i.e. vinylidene chloride/acrylonitrile; vinylidene chloride/methacrylate and vinylidene chloride/vinyl acetate copolymers; polyvinyl chloride and copolymers, i.e. polyvinyl chloride/acetate; saturated and unsaturated polyurethanes; synthetic rubbers, i.e. butadiene/acrylonitrile, acrylonitrile/butadiene/styrene, methacrylate/acrylonitrile/butadiene/styrene copolymers, 2-chlorobutadiene-1,3 polymers, chlorinated rubber, and styrene/butadiene/styrene, styrene/isoprene/styrene block copolymers; high molecular weight polyethylene oxides of polyglycols having average molecular weight from about 4,000 to 1,000,000; epoxides, i.e. containing acrylate or methacrylate groups; copolyesters; nylons or polyamides, i.e. N-methoxymethyl, polyhexamethylene adipamide; cellulose esters, i.e. cellulose acetate succinate and cellulose acetate butyrate; cellulose ethers, i.e. methyl cellulose, ethyl cellulose and benzyl cellulose; polycarbonates; polyvinyl acetal, i.e. polyvinyl butyral, polyvinyl formal; polyformaldehydes.
In addition to the polymeric binders listed above particulate thickeners such as described in U.S. Pat. No. 3,754,920 i.e. silicas, clays, alumina, bentonites, kaolnites, and the like can be used.
Where aqueous developing of the photoresist is desirable the binder should contain sufficient acidic or other functionalities to render the composition processable in the aqueous developer. Suitable aqueous-processable binders include those described in U.S. Pat. No. 3,458,311 and in U.S. Pat. No. 4,273,856. Polymers derived from an aminoalkyl acrylate or methacrylate, acidic film-forming comonomer and an alkyl or hydroxyalkyl acrylate such as those described in U.S. Pat. No. 4,293,635 can be included.
Normally a thermal polymerization inhibitor will be present to increase the stability during storage of the photosensitive compositions. Such inhibitors are; p-methoxyphenol, hydroquinone, alkyl and aryl-substituted hydroqinones and quinones, tert-butyl catechol, pyrogallol, copper resinate, naphthylamines, beta-napthol, cuprous chloride, 2,6-di-tert-butyl-p-cresol, phenothiazine, pyridine, nitrobenzene and dinitrobenzene, p-toluequinone and chloranil. Also useful for thermal polymerization inhibitors are the nitroso compositions described in U.S. Pat. No. 4,168,982.
Dyes and pigments may also be added to increase the visibility of the resist image. Any colorant used however, should be transparent to the actinic radiation used.
An example of such photosensitive compositions is described in Table I of U.S. Pat. No. 4,693,959.
In the preparation of these formulations generally inert solvents are employed which are volatile at ordinary pressures. Examples include alcohols and ether alcohols, esters, aromatics, ketones, chlorinated hydrocarbons, aliphatic hydrocarbons, miscellaneous solvents such as dimethylsulfoxide, pyridine, tetrahydrofuran, dioxane, dicyanocyclobutane and 1-methyl-2-oxo-hexamethyleneimine, and mixtures of these solvents in various proportions as may be required to attain solutions. Antiblocking agents to prevent the coatings from adhering to the supporting files can also be included.
With some polymers, it is desirable to add a plasticizer, either solid or liquid, to give flexibility to the film or coating. Suitable plasticizers are described in U.S. Pat. No. 3,658,543. A preferred liquid plasticizer is nolylphenoxypoly(ethyleneoxy)-ethanol. A preferred solid plasticizer is N-ethyl-p-toluenesulfonamide.
Photoimagable compositions are also utilized as solder masks. In such application a photoimagable composition is used by applying the composition to printed circuit board and followed by photolithographic techniques to expose various underlying features on the board while masking others. During the soldering process the solder will deposit onto the exposed underlying components. It is necessary that the solder mask material be formulated such that it can be applied by the appropriate methods, for example curtain coating. Suitable photoimageable compositions including many that use epoxies are described in the following U.S. Pat. Nos. 4,279,985; 4,458,890; 4,351,708; 4,138,255; 4,069,055; 4,250,053; 4,058,401; 4,659,649; 4,544,623; 4,684,671; 4,624,912; 4,175,963; 4,081,276; 4,693,961; and 4,442,197.
More recently an improved cationically photoimageable solder mask is described in U.S. Pat. No. 5,026,624 assigned to the assignee of the present application, disclosure of which is incorporated herein by reference. In fact U.S. Pat. No. 5,026,624 teaches an improved photoimageable cationically polymerizable epoxy based coating material.
In processing negative working resists, unexposed areas of the imaged film are typically removed from the surface of a printed circuit board or substrate by action of a liquid developer in a spray form for a duration of several minutes or less. Depending on the particular type of photoresist composition the liquid developer may be a simple organic solvent, an aqueous solution of an inorganic base, or as described in U.S. Pat. No. 3,475,171, a combination of organic solvent and aqueous base to form a semi-aqueous developer.
Methyl chloroform (MCF, 1,1,1-trichloroethane), and methylene chloride (MC, dichloromethane) are solvents which are widely used in the electronic packaging art and in other arts for developing and removing a number of photoresists which are otherwise resistant to chemical attack.
The highly alkaline electroless copper plating baths used in additive processes provide a harsh environment for photoresist. In general, the more chemically impervious resists are removable in an organic solvent such as methylene chloride. For less demanding chemical environments, aqueous developable photoresists may be adequate. The organically developable resists, however, continue to be used in an electroless copper environment and in the print band and thin film technologies in conjunction with acrylate-based resist such as DuPont's Riston T-168 and solvent processed solder masks such as the DuPont Vacrel 700 and 900 series, environments in which the aqueous resists are vulnerable.
The use of 1,1,1-trichloroethane and methylene chloride is disfavored because of growing environmental concerns over the effect of gaseous halogenated hydrocarbons on the depletion of earth's ozone layer and concerns over introducing suspected carcinogens to the atmosphere. Several countries have set goals for their total elimination. However, there continue to be many manufacturing processes in which use of resists which are aqueously developable simply is not feasible.
The industry therefore continues the search for organic solvents as alternates to 1,1,1-trichloroethane and methylene chloride. The new solvents must meet specific manufacturing and environmental requirements with respect to flammability, toxicity, ability to effect dissolution, shelf-life, waste disposal, ability to recycle, simplicity of composition, and compatability with a spectrum of resists.
Alternative solvents for stripping solvent based Riston photoresists are also described in Research Disclosures, June 1989, p. 302, published anonymously.
There have been previous attempts reported in the art to provide environmentally friendly alternatives to 1,1,1-trichloroethane and methylene chloride. However, none of the references describe the simple, environmentally acceptable, room temperature developer and stripper of the present invention.
The commonly assigned, copending U.S. application Ser. No. 07/781 542, filed Oct. 22, 1991, of N. R. Bantu, Anilkumar Bhatt, Ashwindumar Bhatt, G. W. Jones, J. A. Kotylo, R. J. Owen, K. I. Papathomas, and A. K. Vardya for Photoresist Develop And Strip Solvents and Methods for their Use, describes the use of 4-methyl -1,2- dioxolan -2-one (propylene carbonate, methyl ethylene carbonate, 1,2-propylene carbonate) as a developer and and as a stripping agent. This material has the structure: ##STR1## Bantu et al describe its use as an alternative to halogenated hydrocarbon developers and strippers for use in developing and stripping acrylate based photoresist such as DuPont Riston T-168 and polymethyl methacrylate, and solvent processed solder masks such as the Vacrel 700 and 900 series.
U.S. application Ser. No. 07/781 542 describes developing the radiation-exposed resist in a high boiling solvent selected from the group consisting of propylene carbonate (PC), gamma butyrolactone (BLO) and benzyl alcohol (BA). The process occurs at about 24 to 45 degrees Centigrade for about 0.5-12 minutes and is normally followed by a warm or cold, deionized or tap water rinse, or alternatively, a low boiling solvent rinse, to remove excess developer.
The solvents of U.S. application Ser. No. 07/781 542 are high boiling solvents, while the common developers of the prior art for developing Riston type photoresists are low boiling solvents. The use of low boiling solvents such as methyl chloroform (MCF), methyl ethyl ketone (MEK), xylenes or mixtures thereof are similar to the methylene chloride stripping process.
By way of contrast high boiling solvents, i.e. n-methyl pyrolidone (NMP), gamma-butyrolactone (BLO), dimethyl sulfoxide (DMSO) and propylene carbonate (PC) must be followed by a rinsing step with compatible solvent or water. Furthermore, in order to obtain dissolution times comparable to those of MC, it is necessary that temperature during stripping be maintained between about 50 degrees Centigrade and 100 degrees Centigrade. However, these requirements add to the expense and difficulty of economically managing the alkylene carbonate effluent, which is non-biodegradable.
Thus, there is a clear need for a low cost process for the management of alkylene carbonate waste streams, for example, propylene carbonate waste streams.

Chemical pre-treatment and biological destruction of propylene carbonate waste streams effluent streams to reduce the biological oxygen demand thereof

International Business Machines Corporation


Disclosed herein is a method for producing plasters that contain chloride contents of less than 0.5% by weight from calcium-containing impure products or residues having a high chloride content (e.g., about 10% or higher based on the total product or residue weight). The method does not require the addition of fly ash, SiO.sub.2 or Al.sub.2 O.sub.3. The method comprises temperature and water-mediated conversion of calcium chloride to calcium oxide in the calcium-containing product or residue using water, steam and/or substances that generate water to obtain calcium oxide and hydrochloric acid; and sulfating calcium components in the product or residue using oxygen and sulfur-containing, largely calcium-free substances. The product so obtained is an anhydride plaster which can optionally be hydrated.

The present invention relates to a method for producing low-chloride plaster products from impure products or residues, which contain calcium and/or calcium compounds, such as sulfites, chlorides, sulfates, hydroxides, carbonates and/or oxides of calcium or mixtures thereof.
Calcium-containing residues are formed, for example, during the removal of sulfur dioxide (SO.sub.2) and other environmentally harmful components from flue-gases or waste gases of coal-fired plants, combustion plants and remelting plants. Methods for the thermal conversion of such residues into plaster products by oxidation and calcining are known. However, residues with high calcium chloride content cannot be processed into high-grade, low-chloride plaster products using known methods. High-grade, low-chloride plasters are useful, for example, in the building industry in the manufacture of calcium sulfite anhydrate for building cement and retarders.
Some calcium-containing residues, such as the spray absorption residues from dry flue-gas purification plants, have CaCl.sub.2 contents of up to 10% by weight. Spray-absorption residues originate from dry or quasi-dry desulfurization installations, which are operated with lime as an absorbent. A method to produce low-chloride anhydrous plaster from such residues is disclosed in U.S. Pat. No. 4,495,162 (European Patent 0,074,772.) The method disclosed in the '162 patent includes the oxidation of a CaSO.sub.3 component of the residue to CaSO.sub.4 (calcium anhydrite). Then, in a separate step, chlorine is removed by exposing the residue to steam at temperatures between 600.degree. and 950.degree. C. To achieve a low chloride content in the product manufactured by this method, large quantities of fly ash or materials containing SiO.sub.2 and Al.sub.2 O.sub.3 are required. Addition of these materials functions to bind the calcium chloride (CaCl.sub.2) components as calcium silicate or calcium aluminate. This is said to facilitate the reaction of the chlorine liberated from the residue and water (steam) to form gaseous HCl.
Despite the availability of this process, plaster products having chloride contents of less than 0.5% by weight are produced only at temperatures well in excess of 600.degree. C. A further disadvantage of this method is the resulting high proportion of silicate and aluminate in the end product.
It is an object of the present invention to provide an effective method for processing calcium-containing impure products or residues to form low-chloride plaster having a calcium chloride content below 0.5% by weight.
Another object of the present invention is to provide a method for making low-chloride plasters from calcium containing residues that contain up to 10% by weight of CaCl.sub.2 at temperatures between 500.degree. C. and 600.degree. C.
A further object of the present invention is to provide a process for making high grade plaster products containing less than 0.5% by weight of chlorine from calcium containing waste materials containing up to 10% by weight of CaCl.sub.2, that is not dependent on the quantity of fly ash, SiO.sub.2 or Al.sub.2 O.sub.3 that is present in the starting material.
A still further object of the invention is to produce low-chloride plaster in either anhydrous form or in a partially hydrated form (beta-hemihydrate form).
These and other objects of the present invention will be apparent to those of ordinary skill in the art in light of the following description, drawings and claims.

Method for the preparation of low-chloride plaster products from calcium-containing residues of flue-gas purification plants


A sleeve connecting a refrigerant pipe to a sealed compressor container has a reduced outer dimension and an inner step that accommodates the refrigerant pipe. An end of the refrigerant pipe abuts the inner step to accurately locate the refrigerant pipe to permit the refrigerant pipe to be secured in an desired relationship with the sleeve. The sleeve is attached to the container with increased accuracy and less chance of damage to the container through deformation during the attachment process. The sleeve and container may be composed of iron, while the refrigerant pipe may be composed of copper, so that the more rigid sleeve can accurately couple the less rigid refrigerant pipe to the container.

1. Field of the Invention
The present invention relates to a compressor for compressing a refrigerant suitable for use in, for example, an air conditioning system, a water heater, a car air conditioner, a showcase, a freezer and refrigerator, or a refrigeration unit such as an automatic dispenser.
2. Description of the Related Art
In such a conventional compressor, for example, in a multistage compression type rotary compressor of an inside intermediate-pressure type, refrigerant gas is drawn into a low pressure chamber side of a cylinder from a refrigerant introduction pipe via a suction port of a first rotary compression element. The refrigerant gas is then compressed by operations of a roller and a vane to become intermediate pressure, and is discharged from a high pressure chamber side of the cylinder through a discharge port and a noise eliminating chamber into a sealed container.
The intermediate-pressure refrigerant gas in the sealed container is drawn into the lower pressure chamber side of the cylinder from a suction port of a second rotary compression element, and then is subjected to a second stage compression by the operations of the roller and the vane to become high-temperature and high-pressure refrigerant gas. The refrigerant gas flows from the high pressure chamber side of the cylinder through the discharge port and the noise eliminating chamber, and is discharged from a refrigerant discharge pipe to the outside of the compressor to be supplied to a refrigerating cycle, such as an air conditioning system, where the refrigerant gas radiates heat and is condensed to enter an evaporator. In the evaporator, heat of the refrigerant gas is absorbed and the refrigerant gas is evaporated. Thereafter the refrigerant gas is drawn again into the first rotary compression element through the refrigerant introduction pipe. This cycle is repeated.
In a sealed-type electric compressor with such an arrangement, a refrigerant introduction pipe or a refrigerant discharge pipe is connected to a cylindrical sleeve which is welded and fixed to a curved surface of a sealed container having a cylindrical shape. The typical conventional structure of the sleeve is shown in FIGS. 6 and 7.
A sleeve 141X as exemplified in FIG. 6 is made of iron material having large rigidity. A tapered tip end side of the sleeve 141X is attached to an outer wall surface of the sealed container made of iron by projection welding with its inner surface brazed and fixed to a pipe member 145X made of copper material having good ductility, but less rigidity than the iron, for connection with a refrigerant pipe.
A sealed pipe having its tip end leading to a cylinder of compression means existing in the sealed container is inserted into the inside of the pipe member 145X made of copper. Into the sealed pipe, a refrigerant introduction pipe or a refrigerant discharge pipe is further fitted and connected.
The sleeve 141X as exemplified in FIG. 7 has a tapered side part with a large thickness, which is attached to the sealed container by the projection welding.
In a compressor including a sleeve having a shape such as that shown in FIG. 6, since a sleeve body incorporates therein the pipe, the sleeve body itself becomes larger than the pipe. This disadvantageously results in an increased diameter of a part which is projection welded, which leads to reduction in the strength of resistance to pressure of the welded part. The method for fixing the pipe involves simply inserting the copper pipe into the sleeve body and brazing it thereto, thus making it difficult to attach the pipe to the sleeve body at the right angle with respect to the body. This causes a problem that attachment of the refrigerant introduction pipe and the like cannot be carried out constantly in the same way.
In a compressor including a sleeve having a shape such as that shown in FIG. 7, since a part of a sleeve that is subjected to the projection welding has a large thickness, when the sleeve is attached to a container body by welding, the container body is largely pushed, thereby disadvantageously resulting in large deformation of the container body.

Sleeve for coupling a refrigerant pipe to a compressor container


Techniques are disclosed for turbo decoding orthogonal frequency division multiplexing OFDM symbols. Techniques for combined turbo decoding and equalization are disclosed. The disclosed techniques can be implemented in receivers that receive wired or wireless OFDM signals and produce data and control bits by decoding the received signals.

Many modern digital communication systems use orthogonal frequency division multiplexing (OFDM) modulation technology. Various types of error correction codes are used to increase robustness of transmitted signals. For example, OFDM and error coding is used in wireless technologies such as Long Term Evolution (LTE) and wired communication technologies such as digital subscriber line (DSL).

Combined turbo decoding and turbo equalization techniques


A projection exposure apparatus that provides uniform illumination with at least partially incoherent light that could produce interference fringes. The projection exposure apparatus includes a light source emitting at least partially coherent light, a dispersion element for dispersing the light according to wavelength, a dividing element for dividing the dispersed light into plural light beams, a condenser unit for introducing each of the plural light beams in an overlapping manner onto a mask including circuit patterns, and a projection lens unit for projecting the light passing through the mask onto a surface of a wafer.

1. Field of the Invention
The present invention relates to a projection exposure apparatus (projection printer) in use for LSI fabrication processes.
2. Description of the Related Art
FIG. 6 shows an optical system of a conventional projection printer. A fly-eye lens unit 3 is arranged in front of a lamp 1 and a mirror 2. In front of the fly-eye lens unit 3, an aperture unit 4, condensers 5 and 6, and a mirror 7 are located. A mask 8 including desired circuit patterns is next to the condensing lens 6. A wafer 10 and a projection lens unit 9 are placed in front of the mask 8. Fly-eye lens unit 3 has a fly-eye lens 12 fixed to an outer frame 13. As shown in FIG. 7, the fly-eye lens 12 comprises a plurality of identical lenses 11 having a rectangular shape in a plan view which are arranged in a two-dimensional array. The line on the fly-eye lens unit 3 designated by alternating long and short dashes corresponds to the edge of an aperture 4a of the aperture unit 4. In FIG. 6, the outer frame 13 of the fly-eye lens unit 3 is not shown and the number of element lenses 11 is reduced for simplicity.
Light emitted from the lamp 1 is introduced to the fly-eye lens unit 3 via the mirror 2. Light which is incident into each element lens 11 of the fly-eye lens unit 3 illuminates all of the mask 8 via the aperture 4a of the aperture unit 4, the condenser 5, the mirror 7, and condenser 6. In FIG. 6, there are shown only light beams which pass through element lenses 11 located at the central part of the fly-eye lens unit 3 to illuminate the mask 8, but light beams passing through the other element lenses 11 also illuminate the mask 8 in similar way so that the whole exposure area is illuminated. As a result, the light beams from each element lens 11 of the fly-eye lens unit overlap on the surface of the mask 8; thus, uniform illumination is achieved. Furthermore, after passing through the mask 8, the light reaches the wafer 10 via the projection lens unit 9 to transfer the circuit patterns onto the surface of the wafer 10.
In such a projection printer, it is known that the illumination with shorter wavelength light results in better resolution suitable for exposure of finer patterns. Therefore, use of an excimer laser producing far ultraviolet wavelength light has been investigated.
However, the laser beam emitted from an excimer laser exhibits high coherence, hence interference patterns appear on the surface of mask 8 also on the surface of wafer 10 when it is used as a light source in the projection printer of FIG. 6. Such irregularity in the illumination is a problem to be solved.


The present disclosure is directed to reducing model size of a machine learning model with encoding. The input to a machine learning model may be encoded using a probabilistic data structure with a plurality of mapping functions into a lower dimensional space. Encoding the input to the machine learning model results in a compact machine learning model with a reduced model size. The compact machine learning model can output an encoded representation of a higher-dimensional space. Use of such a machine learning model can include decoding the output of the machine learning model into the higher dimensional space of the non-encoded input.

Models representing data relationships and patterns, such as functions, algorithms, systems, and the like, may accept input (sometimes referred to as an input vector), and produce output (sometimes referred to as an output vector) that corresponds to the input in some way. For example, a machine learning model may be implemented as an artificial neural network ("NN"). Artificial neural networks are artificial in the sense that they are computational entities, analogous to biological neural networks in animals, but implemented by computing devices. Output in NN-based models is obtained by doing a "forward pass." The forward pass involves multiplying large NN weight matrices, representing the parameters of the model, by vectors corresponding to input feature vectors or hidden intermediate representations. The parameters of a NN can be set in a process referred to as training.

Encodings for reversible sparse dimensionality reduction


Techniques are provided for controlling an on-chip termination (OCT) in an output driver. The OCT control circuit calibrates the effective resistance of transistors in the output driver to match an external resistor using a feedback loop. The feedback loop monitors the output voltage and generates an analog calibration signal that varies the output impedance of a selected group of the output transistors that are enabled to drive the output terminal. Digital signals under the control of the user select the number of output transistors to be enabled based on the output driver requirements of the circuit. The analog calibration signal varies the signal level driving the selected output transistors to modify the effective output impedance of the circuit for better termination matching.

The present invention relates to techniques for controlling on-chip termination resistance, and more particularly, to techniques for precision biasing output drivers for controlling an on-chip termination resistance.
When transmitting signals over distances that are appreciable with respect to the signal period, mismatches between the impedance of the transmission line and that of the receiver cause signal reflection. The reflected signal interferes with the transmitted signal and causes distortion and degrades the overall signal integrity. To minimize or eliminate the unwanted reflection, transmission lines are resistively terminated by a matching impedance. In the case of integrated circuits that are in communication with other circuitry on a circuit board, termination is often accomplished by coupling an external termination resistor to the relevant input/output (I/O) pins.
For many of today's high speed integrated circuits, and particularly those that have large I/O pin counts, external termination poses a number of problems. A termination resistor is typically coupled to every I/O pin receiving an input signal from a transmission line. Often hundreds of termination resistors are needed for an integrated circuit. Numerous external termination resistors can consume a substantial amount of board space. The use of external components for termination purposes can be cumbersome and costly, especially in the case of an integrated circuit with numerous I/O pins.
Signal integrity is critical in digital design as system speeds and clock edge rates continue to increase. To improve signal integrity, both single-ended and differential signals should be properly terminated. Termination can be implemented with external termination resistors on a board or with on-chip termination technology. On-chip termination eliminates the need for external resistors and simplifies the design of a circuit board.
There is some degree of flexibility provided by circuits such as field programmable gate arrays (FPGAs) wherein a user may be provided the option of programmable changing the output driver settings. To reduce die size, an FPGA design may be converted to a structured application specific integrated circuit (ASIC) using a mask field programmable gate array (MFPGA) that fixes the switch settings. This conversion which removes the programmability of the switches and routing become economically desirable at higher volumes. In a structured ASIC design, therefore, the user may loses the option to change the output driver settings. The output drive strength is set according to the user's FPGA design, and the setting is hardwired in the structured ASIC.
A circuit designer can map a user's I/O drive strength settings from an FPGA to a structured ASIC through simulation or test chip correlation. However, process, voltage, and temperature (PVT) variations and other parasitic effects can complicate the mapping effort. Therefore, such a mapping process is not desirable, because the FPGA-to-structured ASIC conversion process typically has a short turn-around time.
One of the objectives when converting an FPGA design into a structured ASIC design is to reduce the die size and the chip production cost. One way to reduce die size is to reduce the number of user drive strength options in the I/O drivers of the structured ASIC design. However, removing user drive strength options compromises the I/O drive strength resolution. As a result, the user may have to settle for a drive strength setting that is different from the FPGA. The user typically wants to keep the same drive strength setting so that the structured ASIC can interface with neighboring chips with the same drive strength settings used in the FPGA.
It would therefore be desirable to implement termination resistance on-chip to reduce the number of external components. It would also be desirable to provide accurate control of an on-chip termination resistance. It would further be desirable to provide the user with the flexibility to adjust the drive strength setting of an I/O driver in a structured ASIC.

Techniques for precision biasing output driver for a calibrated on-chip termination circuit


The invention relates to ester-linked surface-modifying macromolecules and admixtures thereof as shown below by the representative compounds. The admixtures can be used in industrial and medical applications where enhanced surface properties are desirable (e.g., surface properties reducing or preventing biofouling, immobilization of biomolecules, or denaturation of certain biomolecules).

Wetted surfaces can be susceptible to interaction with biological agents, such as proteins, nucleic acids, and living organisms. These interactions can lead to degradation of adsorption of the biological agent (e.g., a protein or a nucleic acid). These interactions can also lead to surface fouling by water constituents such as biomolecules, living organisms (e.g., bacteria), dissolved inorganic or organic compounds, colloids, and suspended solids. Biofouling can be attributable to accumulated extracellular materials such as soluble microbial products and extracellular polymeric substances such as polysaccharides and proteins (see, e.g., Asatekin et al., Journal of Membrane Science, 285:81-89, 2006). For example, membranes that are used for industrial water filtration or in medical applications (e.g., in dialysis) can suffer fouling due to e.g., adsorption of proteins, attachment of suspended particles, or precipitated salts to the membrane. Still other examples of fouling in biomedical applications can generally result from the adherence of, e.g., cells and pathogens to the surface of a medical device (e.g., a catheter or other implantable medical device), and such fouling can have potentially adverse outcomes. Fouling can also be evident on the hulls of marine vessels, which can become coated with marine organisms or their secretions.
Accordingly, compositions and admixtures that have surface properties reducing or preventing biofouling, immobilization of biomolecules, or denaturation of certain biomolecules can be useful in diverse applications in industry and medicine.

Ester-linked surface modifying macromolecules


A clutch mechanism is provided for a cooling fan of a size capable of fitting into the limited envelope available in an over-the-road diesel tractor. A compact housing has a belt drive input and an output connected to the fan hub. The housing includes a pressure chamber in fluid communication with a pressurized air supply and a controllable valve in the air supply line for regulating the pressure in the pressure chamber when the clutch must be operated. The air pressure actuates an internal piston to translate the clutch in a continuously variable manner between engaged and disengaged conditions.. A small envelope clutch, having an outer diameter less than about 9.8 inches in diameter within the fan hub and less than about 6 inches under the belts and 7.3 inches overall so the housing may be positioned between the radiator and the engine, is capable of generating 150 foot-pounds of torque, running a 55 horsepower fan at 2100 rpm, and dissipating 10 horsepower of heat while in the slip mode. The clutch also has at least 130 inches in clutch area.. Fan speed is controlled utilizing a closed loop control system. The control system is capable of monitoring engine conditions and controlling fluid pressure actuating the clutch assembly to control the fan speed in response to the engine conditions.

The field of immediate interest in the present application is that of over-the-road trucking. The economies of trucking dictate that fuel economy should be an important consideration. It is significant not only for large freight line companies owning huge fleets of trucks, but also for the single operator. Much effort has been expended in enhancing the fuel economy of automotive engines including, for example, making the vehicles more aerodynamic, increasing engine efficiencies, and reducing emissions.
The present invention is concerned with the requirement for providing forced air through the radiator for cooling the engine, air conditioning system, intercooler and the like. It is well known that a fan is, at times, needed for cooling and, at other times, unnecessary. It is also well known that the fan can be a major consumer of horsepower, often on the order of 55 horsepower, which will affect vehicle performance. Since horsepower is directly related to the speed cubed, it is desirable to operate the fan at the lowest available fan speed to minimize horsepower consumption. Similarly, it is undesirable to operate the fan when cooling is unnecessary or to overcool the engine. As such, a significant improvement in fuel economy and engine performance may be achieved if the fan is operated only when needed.
It has been found that the smaller pulley ratios have been unable to adequately cool the engine operating at lower engine speeds (typically about 1100 rpm). In order to solve the low fan speed problem and to properly cool the engine, it has been necessary to increase the fan to engine speed drive ratio from about 1:1 to 1.2-1.4:1. The system has been designed to meet the maximum heat rejection at the low engine speeds such as, for example, at about 1100 rpm. Thus, for engine speeds of about 1100 rpm, the fan will rotate at a speed capable of meeting the maximum heat rejection and necessary cooling requirements.
While that might, on the surface, solve the problem of fan speed at low engine speeds, it creates other problems when the engine operates at higher speeds. There can be significant periods of time when the truck is climbing or descending hills and the like, and where the vehicle is operated for extended periods of time at the higher engine speeds. By gearing down, a higher torque is achieved for climbing hills and the like. However, when the pulley ratio is simply changed to boost the fan speed at low engine speeds, the fan will be substantially overspeeded when the engine speed is increased as for hill climbing and the like. Indeed, the increased drive ratio may even attempt to operate the fan above its maximum rated speed. Moreover, operating the fan in the overspeed mode overcools the engine and unnecessarily increases engine horsepower draw and fuel waste.
Attempts of prior fan clutches to either reduce the speed of the fan or declutch the fan in conditions when it is not needed have not been entirely successful. Approaches utilizing dry clutches have typically resulted in on/off operation since the dry clutch could not slip for long without overheating. Inherent in on/off applications is the typical shock load to the drive unit when the drive clutch is engaged. The shock load is not only undesirable from the viewpoint of loading and wear on the mechanism, but is also aesthetically detrimental. When the vehicle is parked, for example, but the engine is running in order to maintain heat or cooling, the fan clutch will typically cycle on and off, creating significant audible disturbance. A further disadvantage of on/off operation is that the system is effectively a coolant temperature loop control system. This introduces a response time delay and the clutch mechanism is incapable of dynamically responding to engine conditions to insure that the fan operates at precisely the desired speed and/or to selectively determine fan speed.
One attempt to avoid the problems with dry clutch fan drives has been the attempted use of viscous coupling between the input and output members of the drive unit. Unfortunately, these approaches have also had their drawbacks. First, viscous couplings have poor release capability and no "lock-up" capability so that the drive input and output members may not be driven at the same speed. Moreover, fan drives using viscous couplings have limited horsepower capability, and cannot quickly dissipate heat from the engine. Most viscous coupling designs are slow to engage after sensing heat, and cannot be completely declutched when cooling is not desired.
Wet clutch mechanisms for driving engine fans have also been used. Wet clutch mechanisms, which typically use oil in the engine sump, have been used to provide relatively continuously variable speed, and will not overheat under most conditions by virtue of the oil-bathed clutch mechanism. If space were not a problem, it would be relatively straightforward to provide a continuously variable relatively reliable clutch mechanism to couple the fan and engine. However, when one appreciates the desires of the truck and engine designers to minimize the space requirements "under-the-hood" and the critical need to efficiently use the under-the-hood space, it will be quickly appreciated that a relatively small envelope is available for the clutch mechanism. The envelope is limited axially by the distance between the radiator and the engine, and it is limited radially, as a practical matter, by the size of sheave which can be accommodated for the pulley driving the fan.
In engines having relatively wide operating rpm ranges, and therefore wide operating oil pressure ranges, the clutch mechanism must have a relatively large hydraulic piston operating area to reliably operate the clutch at the oil pressure extremes, that is, from relatively low oil pressures at idle to relatively high oil pressures at high engine speeds. Similarly, they have required relatively bulky mechanisms to pump or pressurize the oil in the clutch housing As a result, wet clutches with adequate horsepower for fan drive operation have been relatively large.
In some applications, such as off-the-road vehicles including tractors, loaders, graders and the like, there is adequate room in the engine compartment to tolerate the relatively large clutch mechanisms typically associated with wet clutches. However, in other applications where space requirements are more critical, including, for example, over-the-road tractors, the requirements for aerodynamics, appearance, vehicle size, vehicle weight and the like have all combined to reduce the size of the engine compartment. Thus, the relatively large wet clutches having adequate horsepower for fan operation are less compact than desired and may pose a problem for such applications.

Fan clutch for vehicles configured for low engine speed


A method for eroding material, particularly material in a thin-film structure, that includes at least one thin-film arranged over at least one transparent layer, includes irradiating the thin-film with a laser pulse through the transparent layer. The laser pulse has a wavelength in the absorption region of the thin-film. The irradiated thin-film region, together with any layers lying above the thin-film region, are popped off, without any residue, from the transparent layer.

Laser processing methods for cutting or eroding material are known in many technological areas. Generally, a material to be processed is directly irradiated with laser light having a suitable wavelength. The energy from the laser light is absorbed by and coupled into the material in order to evaporate the material. The numerous applications of such processes can include, for example, cutting sheet steel, manufacturing microelectronic components, and structuring thin-film modules.
Laser processing methods have specific applications in structuring thin-film solar modules. For example, a photoactive semiconductor material can be applied across a surface and subsequently subdivided into a number of segments that are serially interconnected. Each of the individual layers of the thin-film structure, such as the front side electrode, the semiconductor layer, and the back side electrode, must be subdivided in order to structure the module surface. Considering the different absorption and dispersion properties of these superimposed layers and their boundary surfaces, lasers provide a suitable tool for such structuring.
However, in subdividing the module surface, the back side electrode is structured in the last step of the process. As a result, such laser processing methods are disadvantageous because the photoactive semiconductor layer lying directly under the back side electrode can be electrically damaged during the last processing step. Specifically, given solar modules composed of an amorphous semiconductor material, there is a risk of a phase conversion resulting from a highly electrically conductive connection between the front and back side electrodes. Further, an electrical short results when highly conductive regions in the semiconductor layer produce a connection between the front and back side electrodes. Further, other damage to the semiconductor layer, such as thermal stressing, also reduces the electrical power of the solar module.
In order to avoid a reduction in the electrical power of the solar module, a lift-off technique is typically used to structure the back side electrode in a thin-film solar module. Such a lift-off technique includes applying a thin line of paste to the active semiconductor layer before depositing the back side electrode on the semiconductor layer. The paste is then mechanically removed from the semiconductor layer after drying, and part of the back side electrode above the paste is also removed.
However, such a lift-off technique has a number of disadvantages. For example, a photo-inactive area having a width greater than 0.5 mm is produced, due to the width of the paste strip. Further, the adhesion between the back side electrode and the active semiconductor layer is locally diminished, due to the lift-off technique. In addition, the photoconduction of the active semiconductor layer can be deteriorated by chemical substances contained in the paste. Moreover, the structuring process of the back side electrode requires several different steps.

Laser processing method for a thin-film structure


Systems and methods for determining operation of a cylinder deactivating/reactivating device are disclosed. In one example, a direction of engine rotation is selected to maximize air flow through the engine while the engine is rotated without combusting air and fuel. Operation of one or more cylinder valve deactivating mechanisms is assessed while the engine is rotated without combusting air and fuel.

Cylinders of an engine may be selectively deactivated to conserve fuel while other cylinders continue to operate to propel a vehicle and to keep the engine rotating. The cylinders may be deactivated by holding intake and exhaust valves of deactivated cylinders in a closed state over an entire engine cycle (e.g., two revolutions for a four stroke engine). Efficiency of cylinders that remain activated increases by improving thermal efficiency and reducing engine pumping losses. Selected cylinders may be deactivated and reactivated responsive to driver demand torque and other vehicle operating conditions. For example, at low engine loads, an eight cylinder engine may combust air and fuel in four cylinders. On the other hand, the same eight cylinder engine may combust air and fuel in all eight cylinders during high driver demand conditions. In other examples, a single cylinder may be deactivated at a time, the identity of the deactivated cylinder varied over a rolling window. In this way, a variable displacement engine (VDE) may enter and exit cylinder deactivation modes (also known as VDE modes) to accommodate different driving conditions.
Over time and varying vehicle operating conditions, the possibility of degradation of one or more valve actuators that selectively activate and deactivate engine cylinder valves may increase. Exhaust valves may be more prone to leakage than intake valves due to higher levels of local carbon deposits. If the valve actuator mechanism is faulty and the valves are not sealing properly, fuel economy is impacted as the inability to seal the cylinder results in a pumping loss which can offset the fuel economy gains from the VDE operation. Continuing to run an engine with leaky exhaust valves from carbon build-up can also thermally damage the valve due to the combustion event releasing large amounts of heat around the valve edges. Drivability issues may also arise as unaccounted air and/or fuel vapors are directed from the leaking cylinder toward an exhaust catalyst. Further, exhaust emissions may be degraded. Accordingly, VDE valve actuation mechanisms may be periodically diagnosed.
One example diagnostic is shown by Doering et al. in U.S. Pat. No. 8,667,835. Therein, VDE valve mechanism degradation is indicated based on a change (e.g., increase or decrease) in manifold pressure over successive induction events of an engine. In particular, the change in manifold pressure over each induction event is correlated with a commanded change in induction state of a cylinder as valves are deactivated.
However, the inventors herein have identified potential issues with such an approach. As one example, since the approach requires the actuation of the VDE mechanism, the opportunities to diagnose the VDE mechanism are limited. VDE mechanisms are typically activated during vehicle travel on a highway and/or cruise conditions when the average engine load is light. If the drive cycle includes largely city driving (with frequent stops and starts), or if the engine is operating under a heavy load (such as when towing operation or carrying a heavy load), conditions for entering a VDE mode may not occur for an extended duration. As a result, it may not be possible to diagnose the VDE mechanism on the drive cycle.
Other example approaches for diagnosing the sealing performance of a cylinder valve deactivation mechanism rely on in-cylinder pressure measurement. However, such approaches may require expensive pressure sensors. Still other methods that correlate the commanded change in induction state with sensed torque changes may lack sufficient clarity and resolution. For example, it may be difficult to differentiate loss of torque due to VDE mechanism degradation from other factors that can contribute to loss of torque, such as cylinder misfire, fuel injector degradation, or spark plug degradation. Further still, a signal to noise ratio for detecting cylinder valve actuator degradation may be low while the engine is operating because exhaust gas recirculation (EGR), barometric pressure, and other engine operating conditions may affect the signal to noise ratio of signals used to determine valve actuator degradation.
In one example, the above issues may be at least partly addressed by an engine operating method, comprising: rotating an engine, unfueled, in a direction reversed from fueled engine rotation; and indicating valve actuator degradation responsive to an intake manifold pressure change rate, sensed without deactivating valves of a plurality of engine cylinders, being less than a threshold different from another intake manifold pressure change rate sensed while deactivating valves of at least one of the plurality of engine cylinders. In this way, cylinder valve actuators may be diagnosed more frequently, and more reliably, while using existing sensors.
As an example, after a duration (e.g., hours) has elapsed since a last key-off event, and while an engine is shut-down, an engine control module may be woken up from a sleep mode. The engine may then be rotated, unfueled, in a direction reversed from a direction the engine rotates in while combusting air and fuel. For example, the engine may be rotated in reverse via an electric motor coupled to an electric H-bridge circuit. The reverse rotation causes the intake and exhaust valves to reverse roles, resulting in the drawing of air from the exhaust manifold via the exhaust valve into the intake manifold via the intake valve. A baseline intake manifold flow and associated steady-state manifold pressure may be established with the valve mechanism of all cylinders active, such as via an existing intake manifold pressure sensor (MAP sensor). Then, cylinders may be deactivated en masse to shift the engine to a VDE mode. For example, valves for 4 cylinders of an 8 cylinder engine may be commanded closed to shift the engine to the VDE mode (e.g., 4 cylinders of one engine bank may be commanded closed while 4 cylinders of another engine bank are maintained active). With half the cylinders operating to "charge" the intake manifold, the time constant required to reach the previously established baseline flow is expected to be larger. If the time constant to achieve a target pressure/flow in the VDE mode is longer than that in the non-VDE mode, it may be inferred that the valve mechanisms are functional. Else, if the time constant in the VDE mode is substantially the same as that in the non-VDE mode, it may be inferred that the valve mechanism for at least one of the cylinders commanded closed is degraded. In an alternate example, such as where the engine is configured to deactivate cylinders individually according to a defined pattern (rolling VDE), each cylinder may be individually deactivated in a rolling manner and a family of curves with increasing time constants may be established for each time a cylinder is deactivated. Responsive to a gap in the family of curves when a particular cylinder is commanded closed, degradation of a VDE mechanism of the corresponding cylinder may be indicated.
In still further examples, additionally or optionally, after waking up, the controller may park a cylinder with a suspected exhaust valve issue in a position where the intake valve is open and the exhaust valve is purportedly closed. The controller may then spin an electric booster coupled to the intake manifold (such as an electric motor coupled to an intake compressor of a turbocharger or electric supercharger) in a direction reversed from a direction the compressor rotates in when the engine is operating boosted. For example, the electric booster may be rotated in reverse via an electric motor coupled to the H-bridge circuit. The intake manifold air flow with the electric booster operating (such as sensed via the MAP sensor or a MAF sensor) is compared to a baseline flow for the given cylinder (such as a baseline flow established with the electric booster running at the same speed during engine testing). A higher than baseline flow is indicative of the exhaust valve not being fully sealed when commanded to close.
In one example, responsive to sluggish engine performance, the controller may perform the reverse engine rotation based diagnostic to identify potentially degraded cylinder mechanisms. The controller may then perform the reverse compressor rotation based diagnostic to pinpoint the identity of the degraded cylinder mechanisms from the suspected cylinders. Alternatively, the controller may select between the diagnostics based on engine operating conditions including a battery state of charge or battery voltage. The selection may also be based on ambient or barometric pressure.
In this way, by rotating an engine or an electric intake compressor via an electric machine in a reverse direction and measuring engine air flow while the engine is rotating, it may be possible to provide the technical result of determining whether or not one or more cylinder valve actuator mechanisms are degraded. In particular, the reverse rotation may provide an increased amount of air flow through the engine as compared to if the engine were rotated in a forward direction because of inherent differences between intake and exhaust valve timing. The increased air flow may provide an improved signal to noise ratio so that valve actuator diagnostics may be improved. Further, a higher air flow rate through the engine may allow the engine to be rotated at a lower speed while still being able to detect cylinder valve actuator degradation reliably. The lower speed may conserve battery power, improving fuel economy. The technical effect of performing the diagnostic while the engine is not combusting fuel is that the interfering effect of poor combustion and degraded fuel injectors or spark plugs is also removed. By using a MAP (or MAF) sensor to determine the intake airflow profile during the reverse rotation while the engine is in the VDE mode, an existing sensor can be repurposed for the VDE diagnostic, reducing system cost and complexity. By comparing the air flow of a suspected cylinder(s) in a VDE mode with a baseline air flow established when the engine is operating with all cylinders active, a leaky exhaust valve of a deactivated cylinder can be identified with high fidelity, allowing for mitigating actions to be specified for the relevant cylinder.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.

System and method for diagnosing a variable displacement engine


Techniques are described for managing periodic communications between devices. For example, a periodic packet process may receive configuration parameters from a routing protocol process. The periodic packet process may manage periodic communication sessions with neighboring devices in accordance with the configuration parameters from the routing protocol process. The periodic packet process may monitor for incoming periodic packets from a specified neighboring device in a specified periodic time interval. The periodic packet process may also send outbound periodic packets at a specified periodic time interval.

A computer network is a collection of interconnected computing devices that can exchange data and share resources. In a packet-based network, such as the Internet, the computing devices communicate data by dividing the data into small blocks called packets, which are individually routed across the network from a source device to a destination device. The destination device extracts the data from the packets and assembles the data into its original form. Dividing the data into packets enables the source device to resend only those individual packets that may be lost during transmission.
Certain devices, referred to as routers, maintain routing information that describes routes through the network. A "route" can generally be defined as a path between two locations on the network. Upon receiving an incoming packet, the router examines information within the packet and forwards the packet in accordance with the routing information.
In order to maintain an accurate representation of a network, routers typically send periodic packets to each other to communicate the state of the device. These periodic packets are sometimes referred to as "keepalives" or "hellos." For example, a first router may send a packet to a second router every five seconds to verify that the router is still operational. The first router may require the second router to respond in a certain amount of time. When a response packet is not received in the allotted time frame, the first router expecting the message may conclude a network failure has occurred, such as failure of the second router or failure of the link connecting the two routers. Consequently, the first router may update its routing information to exclude that particular link, and may issue a number of update messages to neighboring routers indicating the link failure.
However, a number of non-failure conditions may prevent the second router from responding to the first router within the required periodic response time. For example, the computing resources of the second router may be consumed due to heavy network traffic loads. In other words, with the increased amount of network traffic on the Internet, for example, many conventional routers have become so busy performing other functions, such as route resolution, that the response time to periodic packets is not sufficient. Furthermore, the increased complexity of current routers has increased the number of processes concurrently executing on the router, each of which require computing resources. In addition, there has been continual demand to shorten the allowable time to respond to such periodic messages in order to accelerate the detection of network failure conditions.
Failure to respond due to these and other conditions can result in significant network thrashing and other problems. For example, a router may have a route resolution process that requires a significant period of time, e.g., ten or more seconds, for convergence due to the complexity of the network topology. This period may exceed that allowable response time to a periodic packet. By the time the router has sufficient computing resources to respond to the periodic packet, the neighboring router may already mistakenly interpret the router or link as failed. Consequently, the neighboring router may update its routing information to exclude the "failed" router. Furthermore, the neighboring router may send update messages to its neighboring routers indicating the failure, causing its neighboring routers to perform route resolution in similar fashion. Shortly thereafter, the "failed" router may have sufficient resources to send its neighboring router a response packet indicating that it is operational. As a result, the neighboring router again updates its routing information to include the router and sends another update message to its neighbors, causing the neighboring routers to once again perform route resolution. The unnecessary route resolution and update messages cause the network routers to thrash, creating significant network delays.


A premix gas nozzle has longitudinal tangential entrance slots to a cylindrical chamber. There is an axially increasing flow area toward the chamber outlet, with pilot fuel centrally introduced near the outlet. A lean mix low NOx fuel nozzle is thereby stabilized.

Combustion at high temperature leads to the formation of NOx, or oxides of nitrogen, because of the combination of oxygen with nitrogen at high temperature. This is a notorious pollutant and much effort is being put forth to reduce the formation of NOx.
One solution has been to premix the fuel with excess air whereby all of the combustion occurs with a local high excess air and therefore at a relatively low temperature. Such combustion, however, can lead to instability and incomplete combustion.
This problem is exacerbated in gas turbine engines. Once the proper lean mix is set for proper full load operation, low load operation must be considered. At decreasing loads the airflow decreases less than the fuel flow, leading to even leaner mixtures. The air temperature also decreases. Accordingly, flame stability and combustion efficiency (percentage of fuel burnt) becomes an increasing problem.


An apparatus and method of converting a web of indefinite length into a plurality of web portions by slitting the web at a transverse point prior to processing the web portions into a plurality of use supply forms (such as rolls), wherein the plurality of web portions are separated by a two-stage process. A first stage of the process is a partial separation operation that almost entirely separates the web portions, but leaves the web portions connected, such as by a slitting operation that leaves a series of connected zones. The second stage includes the complete separation, such as by breaking of the connected zones. The complete separation of the web portions preferably occurs near the station at which the use supply forms are created, such as a winding station. Thus, the web portions, after substantial separation at the first stage can be handled (for example, guided and tensioned) as if the plurality of web portions were a full width web. But, after handling and transporting of the web portions to the use supply form station, the web portions are completely split so that the plural web portions can be wound or otherwise converted into a plurality of use supply forms.

In some situations, it is desirable to split a single, relatively wide web of material into a plurality of relatively narrow web portions and wind the web portions into several rolls (or otherwise convert the web portions into use supply forms). It is generally more efficient to produce and/or process material in wider webs but often more convenient to package, ship, sell, and/or use the material in narrower rolls. Also, the narrower web portions are preferred or required for some applications. Common examples of web materials that are often split into web portions include paper (for example, toilet paper, computer paper, paper towels, etc.) and tape (for example, adhesive tape, magnetic tape, etc.). Slitting can be done on single webs (for example, films), structured webs (for example, webs with structured features), multilayer laminates, or coated webs (for example, adhesive coated webs for making adhesive tape).
A plurality of web portions can be formed from a web by slitting (or otherwise cutting) the web in the lengthwise direction so that the individual web portions are separated from one another. U.S. Pat. No. 3,695,131 issued to Zimmermann relates to one such approach wherein a web is carried by a traveling support surface across razor sharp cutting edges of circular slitting blades, wherein the web is held on the traveling support to reduce longitudinal or transverse shifting of the web portions. The slitter blades are rotated so as to distribute wear uniformly about the circumferences of the slitter blades. After slitting, the various web portions are directionally separated by directing adjacent web portions through different guide means that thread the web portions to different winding reels.
U.S. Pat. No. 2,897,893 issued to Rockstrom et al. relates to another slitting mechanism in which a continuous web of material is taken from a mill roll and passed over a compensating roll in a rewind machine and under a cutter roll against which the web is slit into web portions before winding into a rewind roll. Slitting wheels bear against a hardened sleeve of the cutter roll at any desired position along the sleeve and they bear with sufficient pressure to sever the web into web portions. The slitting wheels are softer than the hardened sleeve and, although preferably not given a sharp edge, they divide the web. Immediately after the web is cut by the slitting wheels, an angular-faced spreader having a vertical, forward-extending center with backswept sides bears against the web with the forward center of the spreader bearing on the line of the cut to push the web portions apart and to assure their complete separation along the cutting line. U.S. Pat. No. 1,465,967 issued to Cameron et al. relates to a somewhat similar slitting and rewinding machine that also includes a secondary separating device having a knife blade for severing any stray fibers connecting adjacent web portions that have not been severed by the slitting action. The secondary separating device severs the stray fibers after slitting and before winding of the web portions.
After the plural web portions are split and separated, they typically pass individually through guiding and tensioning rollers and then are ultimately wound about a core to form a roll of web material. Each web portion may be individually guided to a distinct core, or plural cores can be supported in axial alignment on a single shaft. Often, adjacent web portions are divided to different winding shafts supporting such plural cores so that they can be guided without interfering with one another. Alternatively, the plural web portions can ultimately be folded, cut, or otherwise processed to form a stack (or other form) of web material. The roll or stack of web material is the use supply form that is used by the consumer of the web portions. To process the split, separated web portions to create use supply forms, each web portion must be individually guided, which requires accurate control to prevent each web portion from wandering. Tension control is an important aspect of web guiding, and web properties (such as the thickness of the web across the web) can cause slight variations in guiding and tensioning each web portion. Variations in guiding and tensioning can cause the web portions to wander and be wound with uneven edges and, where several rolls are wound side by side about a common winding shaft, to be wound with overlapping and interweaved edges that cause the several rolls to become intermeshed.
It is also known to perforate web or web portions prior to forming the use supply forms in order to provide a perforation or tear line so that someone or something provided with the web material in use supply form can split the web material by tearing along the perforations. The perforation or tear line is formed by cutting a plurality of small, spaced slits in the web material. The connections of the web material that remain between the slits maintain the structural integrity of the web material until the connections are torn to further separate the web or web portion along the perforation line. A number of different configurations of perforations lines have been developed.
Perforations can be created in the machine direction of a web or web portion by a perforating wheel having a beveled cutting edge in which one or more notches are formed at angularly spaced intervals so as to define cutting and non-cutting portions of the cutting edge. Typically, several perforating wheels are spaced and rotatably mounted along a bar so that the perforating wheels tangentially contact the outer surface of a back-pressure roll, which is rotated by a motor or the like. The rotation of the back-pressure roll causes the perforating wheels to rotate. The web is run between the perforating wheel and the back-pressure roll and, as the perforating wheels rotate and the cutting portions of the cutting edges come into contact with the web, the cutting portions of the cutting edges penetrate and cut the web to form the perforations. When the perforating wheels further rotate and the non-cutting portions move over the web, the notches formed in the cutting edges prevent the web from being cut, which forms the connections in the perforation line. A perforating wheel of this general type is disclosed in U.S. Pat. No. 3,978,753 issued to Meaden et al. Thus, perforations can be provided in the longitudinal direction so as to define two or more connected web subportions that are wound or stacked into the use supply form.
Perforations can be provided across the transverse width of the web or web portion so as to define individual sheets of the web material. Examples include paper towels and toilet paper, which are typically perforated so that individual sheets can be separated from the roll by the consumer. Many techniques have been developed to make transverse perforation as a web is moved in a machine direction. Most rely on a perforating roll that creates the perforation lines at spaced intervals on the web based upon a notched cutting edge extended transversely on the roll. Whether longitudinally or transversely perforated, such connected web subportions are designed to be separated by a consumer as the web material is converted from its use supply form.
One noteworthy application of perforations in web or web strands is in continuous paper of the type commonly used in computer printers, especially contact or dot matrix type computer printers. Continuous paper of this type is commonly sold as a stack or roll of paper having rows of perforations across the width of the paper. The spacing of the these rows determines the length of the page. Typically, the paper is folded along the perforations alternately in opposite directions, resembling a fan or accordion. Such continuous paper can be moved past a printer mechanism of a printer using a friction feed mechanism that pinches the paper between two rollers, one of which is typically driven by a motor. However, when more than a few pages are printed using only a friction feed mechanism, the continuous paper tends to wander out of alignment.
One solution to the wandering problem adapted for contact or dot matrix type computer printers involves the use of a tractor feed mechanism in which sprockets engage holes in special computer paper. The computer paper is continuous as described above but also has a narrow guide strip on each side along the length of the paper. The guide strips have a plurality of regularly spaced holes for engaging the sprockets in the tractor feed mechanism to advance the paper. Each guide strip is typically separated from the sheet by perforations that define tear lines.
Although the pages of a printout (the printout being computer paper on Which the printer has printed) are sometimes left joined together end to end, the guide strips on the sides are usually removed. Because removing the guide strips after the paper has exited the printer can be time consuming (for example, if the guide strips are removed page by page) and/or can damage the paper (for example, if the guide strips are removed from several sheets of folded paper at once), several approaches to separating the guide strips from the paper immediately after printing but before the paper exits the printer have been developed. For example, U.S. Pat. No. 5,259,543 issued to Downing relates to a parting tool that can be attached to a tractor feed mechanism for separating the guide strips from computer paper as the paper passes through the tractor feed mechanism. The parting tool includes a blade intersecting the plane of the paper for shearing the paper along the perforations connecting the guide strips to the sheets of paper.
The continuous and computer papers described above are provided to the consumer in use supply form with perforations provided in the web material in its use supply form. Separation of the perforations occurs, if ever, at or after use by the consumer. In other words, the perforations are not separated in the process of making the use supply form.

Method and apparatus for slitting and processing a web into plural use supply forms


A data transmission apparatus transmits data signals “S1” and “S2” containing identical serial data “ds” in two frequency bands, and a data reception apparatus receives those data signals “S1” and “S2.” Parallel data “dpl” and “dpl2” obtained from the data signals “S1” and “S2” is subjected to selection or synthesis in a subcarrier selection/demodulation circuit so as to be demodulated into serial data “dsx,” which is then outputted to a MAC section.

1. Field of the Invention
The present invention relates to a wireless communication apparatus and a wireless communication system for performing wireless communication. More particularly, the present invention relates to a wireless communication apparatus and a wireless communication system that employ a multiple-carrier transmission method such as the OFDM (orthogonal frequency division multiplexing) method for transmitting AV streams and data on a wireless basis.
2. Description of the Prior Art
In recent years, as methods for transmitting data and AV streams on a wireless basis, among others, those complying with IEEE802.11b, using the 2.4 GHz band, and IEEE802.11a, using the 5.2 GHz band, have been becoming increasingly popular. Radio waves in the 2.4 GHz band tend to propagate less rectilinearly than those in the 5.2 GHz band, and this gives the former the advantage of readily propagating around the corners of a shielding object and the advantage of offering longer wireless transmission distances. However, the 2.4 GHz frequency band is used comparatively freely, and is shared by other communication methods such as Bluetooth and by the radio waves emitted from microwave ovens. Thus, in the 2.4 GHz frequency band, interference with such other microwaves tends to lower the effective throughput of communication.
Accordingly, in a case where the method complying with IEEE802.11b is used for data transmission such as file transfer in a wireless LAN (local area network), it is not absolutely necessary to guarantee any specific QoS (quality of service), i.e., to give a guarantee that a particular amount of data is transmitted within a particular length of time. Thus, interference with unrelated radio waves does not cause any problem. However, in a case where high-quality images and sounds are transmitted on a wireless basis, it is necessary to guarantee a certain QoS, and therefore interference with unrelated radio waves causes an unacceptable lowering of the effective throughput.
By contrast, the method complying with IEEE802.11a, which uses the 5.2 GHz band, adopts the OFDM method, and, by using a plurality of subcarriers spread over a wide frequency band, achieves a high physical transmission rate and a high effective throughput. Thus, this method creates a transmission state that offers efficiency high enough to guarantee a desired QoS. However, radio waves in the 5.2 GHz band tend to propagate more rectilinearly than those in the 2.4 GHz band, and this gives the former the disadvantage of less readily propagating around the corners of a shielding object and the disadvantage of offering shorter wireless transmission distances. Thus, in wireless transmission performed over a wide frequency band, when frequency-selective fading occurs due to factors in the indoor or outdoor transmission environment, reception condition may become poor with particular subcarriers only, resulting in the missing of the data transmitted by those subcarriers.
To prevent such missing of the data carried by a particular subcarrier, there has been conventionally proposed a diversity receiver wherein reception is achieved by the use of a plurality of antennas and, for each subcarrier, the signals received via the different antennas are corrected and then synthesized together, or a diversity receiver wherein, for each subcarrier, the signal strengths or the like of the signals received via a plurality of antennas are compared with one another so that a signal being received in good reception condition is selected and demodulated (see Japanese Patent Application Laid-Open No. 2000-36801). There has also been conventionally proposed a diversity receiver wherein a plurality of antennas are used and, for each subcarrier, the carrier levels of the signals received via the different antennas are checked so that a signal being received in good reception condition is selected (see Japanese Patent Application Laid-Open No. 2000-174726).
Thus, for example, in a case where the frequency band used is the 5.2 GHz band as with the method complying with IEEE802.11a, by using the diversity receiver proposed in one of the patent publications mentioned above, it is possible to receive OFDM signals via a plurality of antennas. Here, an attempt is made to prevent the deterioration of subcarriers by exploiting the differences in characteristics of the frequency-selective fading occurring in the individual OFDM signals received by the different antennas.
However, the diversity receivers proposed in the Japanese Patent Applications Laid-Open Nos. 2000-36801 and 2000-174726 mentioned above use only one frequency band, and therefore, when the plurality of antennas are arranged close to one another spatially, the signals received by the different antennas may show similar frequency-selective fading characteristics. In that case, the subcarriers of an identical frequency obtained from the OFDM signals received via those antennas exhibit similar degrees of deterioration. Thus, the result of synthesis of those subcarriers, or the result of comparison among and selection from them, may be less accurate than the results for other subcarriers.
In particular, in a case where OFDM signals in the 5.2 GHz band are received, when the plurality of antennas are arranged close to one another spatially, all the relevant radio waves may fail to propagate around in similar manners with respect to the different antennas, or may fail to reach the antennas due to the transmission loss that the radio waves in that frequency band inevitably suffer along the spatial transmission paths. This results in poor reception condition via all the antennas.

Wireless communication apparatus and wireless communication system