A method for the in-situ extraction of gas from coal seams is provided. Flow paths are produced in gas-containing coal by opening up the structure of the coal by introducing into a bore hole that is sunk into the coal at least one gas and/or liquid under pressure over a prolonged period of time at a pressure that is less than the lowest principal stress determined in a respective seam layer from which gas is to be extracted. The introduction into the bore hole is carried out with a cyclically fluctuating pressure. Gas is subsequently extracted via the bore hole.

The present invention relates to a method for the in-situ extraction of gas from coal seams, whereby to provide flow paths in the coal, the structure of the gas-containing coal is opened up by means of gases and/or liquids introduced under pressure into a bore hole that is sunk into the coal seam, and subsequently applying to the bore, for the gas extraction, a pressure that is less than the respective desorption pressure.
The recovery possibility of methane that is present in coal seams from coal layers not opened up by miners by means of an in-situ extraction from bore holes sunk into the pertaining coal seam is determined by the parameters of gas content, permeability, and porosity of the coal, as well as by the desorption pressure of the methane, which is a function particularly of the gas content of the coal. To extract the methane, in connection with heretofore known methods stimulation techniques have been used that are known from petroleum extraction; in this connection, the bore hole that is sunk into the coal seam from which gas is to be extracted is briefly, i.e. over a time period of less than one hour up to a few hours, subjected to a uniformly high pressure, for example from 300 to 350 bar, by means of injection of water or a suitable gas.
This pressurization leads to the formation of a so-called frac, or formation fracturing, by means of which the macro structure of the coal is broken up along its natural mechanical weak points, such as clefts, fissures, etc. The pressurization takes place accompanied by the simultaneous introduction of a suitable material, for example a loose sand, by means of which the opened-up macro structure is kept open and simultaneously a gas stream path is produced along the broken-up mechanical weak points. With the known methods, to this extent merely the acess surface into the extraction bore hole is enlarged.
The known stimulation methods have the drawback that with them it is possible to achieve satisfactory gas extraction rates in coal seams having a low permeability only if the coal is highly saturated with methane and consequently the desorption pressure is relatively close to the pressurization pressure. In contrast, if a low permeable coal is under saturated, there results, proceeding from the respectively introduced frac, only a low penetration depth of the pressure flare or funnel that is established upon reducing the pressure for the gas extraction. The extraction pressure that is to be established below the desorption pressure at the bore hole therefore acts only upon a relatively small volume of coal, namely that which exists directly perpendicular to the respective frac. Thus, the known stimulation technique affects only relatively small seam sections; there occurs at least over a short period of time no volumetric seam effect, and the migration speed of the pressure drop in the seam during the extraction operation is too low.
Consequently, with a low permeability and a low desorption pressure of the coal from which gas is to be extracted, the time period for dropping below the desorption pressure in an economically interesting coal volume is correspondingly long; the gas extraction rates that can be achieved can then be so low that there is no economical gas extraction.
It is therefore an object of the present invention to provide a method of the aforementioned general type by means of which the gas extraction rates can be increased.
The realization of this object, including advantageous embodiments and modifications of the invention, can be seen from the content of the patent claims that follow this description.
The basic concept of the present invention is that to open up the coal, pressurization of the bore hole that is effective over a prolonged period of time is established with a pressure that is less than the lowest principal stress determined in the respective seam layer from which gas is to be extracted, whereby the pressurization of the bore hole is effected during the opening-up time period with a cyclically fluctuating pressure.
The present invention has the advantage that the pressurization of the coal seam from which gas is to be extracted with a pressure that is less than the lowest principal stress determined in the seam in question opens the complex fissure system present in the coal in the pore range of macro pores up to micro pore structures, without new fissures in the range of the macro structure opening or having to open. Subsequent to the opening-up of the pore structure, the micro fissures do not return to their tight or impermeable starting position since due to the longer lasting pressurization with a pressure that is in the range of the principal stress, a low dislocation of the micro fissure surfaces relative to one another is produced, and due to the separation of very fine particles connected therewith, a permanent gap is generated on the respective fissure surface, so that advantageously it is also possible to eliminate the use of support material such as sand, etc.
The opening of the fissure system in the pore range is furthermore enhanced pursuant to the present invention by pressurizing the bore hole during the opening-up time period with a cyclically fluctuating pressure, so that in so doing there results a kind of breathing in the pore range of the coal that is to be opened up, as a result of which once pore structures have opened they cannot close again. This also enhances the shifting of the micro fissure surfaces relative to one another, and the transport of loosened very fine particles within the opened micro pore structures.
Thus, with the inventive method the permeability of the coal is permanently increased over a larger surface area without, during the subsequent extraction operation, having to pump a larger volume of coal to a pressure level below the desorption pressure, so that this larger coal volume, having the permeability increased by the inventive measures, is available for gas extraction.
To determine the pressure that is to established in individual cases, the lowest principal stress that exists in the coal seam from which gas is to be extracted is measured, and the pressurization pressure is set lower than the determined principal stress; the pressurization takes place over a prolonged period of time that is measured in terms of one day up to many days or weeks. This long-lasting pressurization with the pressure that is a function of the given principal stress leads to the desired opening-up of the pore structure of the coal without alterations in the mechanical structure of the coal seam developing.
Pursuant to one specific embodiment of the present invention, during the opening-up time period, periods of pressurization of the bore hole can cyclically alternate with periods of gas extraction.
Pursuant to specific embodiments of the present invention, the pressurization of the bore hole can be effected by pressing water or gas in. To the extent that water is used for pressurization of the bore hole, seam water that is present at the site can be pressed into the bore hole, or by means of cyclically applied pressure the breathing of the pore structure can be produced via the pressure inducement of the seam water. In the same way, pursuant to another specific embodiment of the present invention, the gas that flows to the bore hole and is extracted can be pressed back into the bore hole for the pressurization thereof; alternatively, it is also possible to press in CO2, which has the advantageous effect that during the entry of CO2, the affinity of the methane (CH4) that is to be extracted to the coal is reduced, so that the CO2 gas that is utilized for the pressurization at the same time acts as an extraction aid.

Method for the in-situ extraction of gas from coal seams


The present invention assesses memory (DIMM) strength by calculating frequency content of a radiated field which is collected by an apparatus, such as a dipole antenna. Radiated field is created by accelerated charge, which is a function of the slew rate or DIMM strength. Radiated power is directly proportional to the frequency at which bits are driven. By separating the radiated field from the near field or stored field, the DIMM strength content is isolated from other functional DIMM issues, such as tRCD latency, refresh cycles, addressing mode, etc. By examining the radiated power, the disadvantages of the prior art, such as by probing the DIMM's contacts, are avoided.

To assess the driver strength of DIMMs in high performance high speed server systems, in prior art systems, there is a need to probe at the chip pad interface while the device is in operation. A DIMM, or a Dual In-line Memory Module, is one popular type of memory module. The DIMM is a rectangular low-profile circuit board that has electrical contact points arranged on both sides along one long edge. The contact points form electrical connections to the main board's memory bus when the DIMM is inserted into a DIMM memory socket. Today, there is the ability to measure at the pin of the chip or memory controller to assess the drive strength. (A memory controller is a chip on a computer's motherboard or CPU die which manages the flow of data going to and from the memory.) The disadvantage in using this kind of approach is that the trace itself produces unwanted stub loading into the probe and signal under test. (Stub loading on the main bus can be caused by excessively long stubs and/or stubs terminated in low impedances and can load down the main bus and result in transmission line reflections, and therefore waveform distortions.) This can have the effect of increasing the bit error rate for terminals receiving data on the bus, or in extreme circumstances, cause terminals to stop receiving completely. Another disadvantage is the uncertainty in being able to repeat the measurement consistently.
Multiple time probing can result in damaging the BGA pins. (A ball grid array (BGA) is a type of surface-mount packaging used for integrated circuits.) Use of sophisticated probe stations is one way to over come this limitation, but probe stations that provide this kind of measurement capability are expensive and cost 100s of thousands of dollars.
There is currently a need for inexpensive test jig for assessing DIMM strength. (A jig is an adapter for connecting electronic devices to a service and maintenance system for testing, debugging and firmware update purposes.)

Method and apparatus for repeatable drive strength assessments of high speed memory DIMMs

International Business Machines Corporation


A programmable telephone system including system software and system hardware. The system software includes instructions for operating the telephone system, and requires license information to operate. The system hardware includes a system specific memory and a system board. The system board executes the instructions of the system software. The system specific memory store is the license information and is separately replaceable from the system board in the system hardware.

The present invention relates in general to reducing the Mean Time To Repair (MTTR) in programmable systems having both hardware and software portions. The present invention relates in particular to programmable systems where the software is used under a license agreement and requires license information before operating in a basic mode and/or operating optional features.
Programmable systems are becoming larger, more complicated and more versatile, in particular with regard to internal telephone systems for companies and organizations. These internal telephone systems are also known as Private Branch Exchanges (PBX) and are performing more functions, such as voice mail, call forwarding, email, call tracking and billing. This has become possible through the use hardware that can be controlled by software. The hardware performs relatively small, but numerous, and almost generic individual operations under the control of the software. As more features are added, the software in such PBX""s is becoming larger, more complicated and more valuable.
Very often a PBX system will be offered for sale with a plurality of different options or additional features for different prices. These different options or additional features are usually enabled either by adding additional software or enabling previously disabled portions of the core software. The costs of generating and testing software can be high for complicated features resulting in high sale prices. The high sale prices in combination with the desirability of additional features, and the fact that software is very easily copied and transferred, results in unauthorized software use and the loss of profits.
One way in which unauthorized software use is controlled is through the use of license information. The software requires that license information be provided before the software can operate. Very often before the software can begin, or additional features can be used, the license information needs to be provided from a source external to the software. The software can ask the operator for the license information each time the license information is required. The license information can also be stored in the hardware that operates the software.
Because the security provided by the license information is desired to be very high, the license information is usually very lengthy and complicated. Having the operator enter the license information each time the license information is required, is very annoying on the part of the operator. Therefore storing the license information in the hardware operating the software is more desirable. The license information is entered by the operator when the PBX system is installed, and additional license information is added whenever additional options or features are added to the system.
A disadvantage of storing license information in the hardware operating the software, is that when the hardware needs to be repaired or replaced, the license information in the hardware is lost. Since the license information is usually only added to the system at the installation of the system or options, paper records of the license information is often lost or unavailable to the operator when a repair or replacement of the hardware occurs. Repairs to hardware are often requiring more time to obtain the license information, especially license information for any upgrades of optional features, than the time to perform the actual physical repair.
It is a primary object of the present invention to reduce the repair time in a programmable system requiring license information, especially a programmable telephone system.
The present invention accomplishes this object by providing a system specific memory for storing the license information. This system specific memory unit is arranged in a stable portion of the programmable system that is separate from a majority of other replaceable system hardware, especially the hardware that operates or runs the system software. The system specific memory is designed to have high reliability, usually a higher reliability than many other of the components of the programmable system. Also the entire stable portion of the programmable system that includes the system specific memory is designed for high reliability. In this way, the portion including the system specific memory will not need to be often replaced and when other hardware of the system needs to be replaced, the license information does not need to be re-entered.
The present invention is economically practical because many types of memory have a high reliability, and a relatively low cost. While it is often desirable from a manufacturing viewpoint to combine as many components as possible into one unit or module, the present invention has found it advantageous to separate a portion of the hardware storing the license information from the remaining hardware, and to have the memory storing the license information to be of high reliability and to be stable.
When a programmable system, such as a PBX, is designed, a system board is provided for operating or running the software. In order to operate the software, the system board contains a main memory which contains both the actual software code and other information concerning the system and/or the specific system board, such as the serial number of the system board, the manufacturing date and information concerning revisions to the system board. While it would be convenient to include license information in this memory, the present invention specifically arranges license information in a separate memory on a unit or module which is separately replaceable from the system board and has a higher reliability than the system board. The system board is generally more complicated than a memory unit because it has more active components and many of these components are inherently less reliable than a memory component. It is therefore possible to provide a separate memory component for the license information which is more reliable than the system board and where the system board is separately replaceable, while still providing a system that is economically practical.
The actual memory component can be any device which has a higher reliability than the system board and where the system board is separately replaceable, preferably in the field, from the memory component. One embodiment of the system specific memory could be a memory Integrated Circuit (IC) such as an Electrically Erasable Programmable Read Only Memory (EEPROM). The EEPROM could be mounted on a Printed Circuit Board (PCB) of the system that only includes inherently stable components. A preferred PCB for the EEPROM would be a disk interface PCB for a main memory unit, such as a disk drive tray of the system. If the system or main processor board needed to be replaced, this could be performed without replacing the disk drive tray. Another possibility would be that the system specific memory is on a separate board or card which plugs into either the main system processor board, or a connection strip/plane that connects the individual units or modules of the telephone system. A still further possibility for the system specific memory is a memory chip which plugs into a socket mounted so that it is repetitively removable from whatever support structure it is connected to, if that support structure needs to be replaced. The socket holds the memory chip by a biasing clamping action, preferably on the electronic leads of the memory chip. When the supporting structure needs to the replaced, the memory chip is pulled or pried from the defective board and then inserted into the replacement board. The system specific memory in all of the possibilities is preferably non-volatile.
The system specific memory can also be used to store custom settings of the telephone system, such as the names of the individual users, their extension numbers, etc.
By providing non-volatile storage in a portion that does not normally get replaced, the present invention has significantly decreased the xe2x80x9cmean time to repairxe2x80x9d (MTTF) of the system. Upon system startup, the software of the present invention reads the contents of the system specific memory and enables/configures the telephone system according to the license information and custom settings in the system specific memory.
In many cases, the types and amount of optional software that a customer orders increases over time. When a customer initially purchases a telephone system, the number of users may be low, the need for special features be nonexistent or low, and the money available to purchase a telephone system may also be low. As time progresses, the number of users may increase, the customer""s situation may change and additional features are desired, and additional money may become available to add additional features. During the installation, license information is provided for the initial configuration. As additional features and options are added, additional or replacement license information is provided for the new features or options. If the current license information stored in the system is lost, such as due to a system processor board replacement, finding the proper license information in a customer""s or vendors personal records can be very time-consuming, especially when the license information has changed due to upgrades or additional features being added. Often the time required to find the proper license information is measured in days, while the actual physical hardware replacement is measured in hours.
The separately replaceable system specific memory of the present invention with its high reliability address this problem. In the present invention, a failure of a main processor board or other similar system module would not require replacement of memory containing license information. The defective unit would be removed and a replacement unit would be installed. Upon re-starting of the system, the license information would be read by the software from the original system specific memory, even if the software and the hardware running the software were replaced. The re-started system would then be re-initialized to its original configuration eliminating the need to re-load the correct license information and other custom settings.
The xe2x80x9cmean time to repairxe2x80x9d (MTTR) is a key factor in telephone system reliability and availability metrics. The present invention provides for rapid replacement of a system component and return of the system into operation. Many companies and organizations are highly dependent on telephone communication, and work productivity significantly decreases when a telephone system is not operational. Decreasing the xe2x80x9cmean time to repairxe2x80x9d increases the desirability of a telephone system in many applications, and the present invention is therefore an improvement in programmable telephone systems.

System for maintaining PBX license key information in the event of a hardware failure reducing MTTR


A loader for mounting an elongated load onto the roof an automobile includes an axle, a pair of wheels mounted on the ends of the axle, an elongated stabilizer bar, a pair of tie-down straps and a pair of vacuum cups. The stabilizer bar is centrally mounted on the axle and the tie-down straps are mounted on the axle between the stabilizer bar and the wheels. During use, the vacuum cups are attached to the rear windshield of an automobile, the end of the stabilizer bar bears against the rear windshield and the tie-down straps are attached to a convenient portion of the automobile. The front portion of the load is placed on the wheels and the back of the load is lifted and the load is rolled onto the roof of the automobile.

The present invention relates generally to the field of loaders for automobiles and more particularly to a loader for mounting a kayak or similar load onto the roof of an automobile.
The prior art related to loaders for automobiles includes the following U.S. Patents.
U.S. Pat. No. 2,247,128 to A. M. Levey shows a boat and luggage carrier which includes an arch-shaped frame or bracket which supports a track and a supporting member. The frame is of extended length and has an end which is attached to the rear bumper of an automobile. The track has a curved portion which projects upwardly from the bumper and a straight portion which projects toward the front of the automobile. The forward end of the track is attached to the front bumper of the automobile by a strap. A plurality of rollers are attached to the track at fixed intervals to facilitate positioning a boat or a luggage box on the roof of the automobile.
U.S. Pat. No. 3,712,524 to Ames, Sr. shows a boat loader for automobiles which includes a roller which is supported by a pair of A-frame supports on the trunk lid of an automobile. The supports space the roller a substantial distance above the trunk lid to facilitate rolling a boat onto a rooftop carrier.
U.S. Pat. No. 4,003,485 to Edgerton shows a vehicle-top loader which includes a carriage which rests on a vehicle-top rack. For loading and unloading the carriage is moved across the track and pivoted downward to a slanted position alongside the vehicle. An extendable lever is used to aid in lifting the loaded carrier to vehicle-top height.
U.S. Pat. No. 4,531,879 to Horowitz shows a boat loading and carrying device which includes a base attached to the roof of a car. A rack is pivotally attached to the rack so that the rack can pivot between an inclined surface wherein the rack is angled downwardly and rearwardly from the roof of the automobile for loading and unloading to a loaded position parallel to the roof of the automobile. The boat is pulled onto the rack by a rope and winch system.
U.S. Pat. No. 5,535,929 to Neil shows a tip-off luggage carrier apparatus which includes a storage shell which is attached by struts and wheels to a shell. The shell can be moved from a carrier position atop a vehicle to a loading position adjacent the vehicle and to a position completely removed from the vehicle.
U.S. Pat. No. 5,957,350 to Giles shows a kayak loading device employing guiding rollers and a roof rack attachment mechanism. The device incorporates a plurality of rollers which are oriented in a xe2x80x9cVxe2x80x9d configuration by rigid struts attached to a crossmember. Padded feet extend downwardly from the crossmember. An attachment mechanism extends forward from the crossmember to attach the crossmember to a vehicle roof rack crossbar.
Despite the developments of the prior art there remains a need for a loader for mounting a kayak or similar load onto a roof of an automobile which is compact and can be easily stored in the trunk of an automobile and which can be easily mounted on and removed from an automobile.
It is an object of the present invention to provide a loader for mounting a kayak or similar load onto the roof of an automobile which can be quickly and easily mounted on and removed from an automobile.
Another object of the present invention is to provide a loader apparatus which can be easily stored in the trunk of an automobile.
Another object of the present invention is to provide a loader apparatus which is capable of reliable long term operation.
Yet another object of the present invention is to provide a loader which comprises a relatively small number of components which can be manufactured economically in volume resulting in a relatively low unit cost.
The foregoing and other objects and advantages of the present invention will appear more clearly hereinafter.
In accordance with the present invention there is provided a loader for mounting a kayak or similar load onto the roof of an automobile which includes an axle, a pair of wheels mounted on the end of the axle, an elongated stabilizer bar, a pair of tie-down straps and a pair of vacuum cups. The stabilizer bar is centrally mounted on the axle and the tie-down straps are mounted on the axle between the stabilizer bar and the wheels.
During use, the vacuum cups are attached to the rear windshield of an automobile, the end of the stabilizer bar bears against the rear windshield and the tie-down straps re attached to a convenient portion of the automobile. The bow of a kayak is placed on the wheels and the stem of the kayak is easily rolled onto the roof of the automobile.
Alternatively, the kayak can be mounted onto the roof of the automobile by mounting the vacuum cups on the hood of the automobile with the stabilizer bar bearing against the hood of the automobile. The ends of tie-down straps are attached to the front bumper of the automobile. The bow of the kayak is placed on the wheels and easily rolled onto the roof of the automobile.

Loader for mounting a kayak or similar load onto the roof of an automobile


A dissolution sampling apparatus which automatically extracts aliquots which contain a dissolved drug in solution from a plurality of dissolution containing flasks and tests each aliquot for the amount of drug dissolved within the aliquot. The sampling apparatus can resupply the removed aliquot. back to its source or the aliquot can be discarded as waste with new media being resupplied to the source. A syringe is used to remove the aliquots. A mechanically operated valve could be used with each syringe or a plurality of solenoids instead of the mechanically operated valve.

1) Field of the Invention
The field of this invention relates to dissolution testing equipment for determining the dissolving rate of drugs encapsulated in the form of a tablet, capsule or caplet, which are commonly known as pills and more particularly to an interfacing piece of equipment to be used as a dissolution sampling apparatus.
2) Description of the Prior Art
Drugs are commonly manufactured in the form of pills. The reason for using pills is that when the drug is swallowed by a human, the drug will be disseminated by the body over a period of time as the pill dissolves. Manufacturers of pills are required by law to determine the precise dissolving characteristics of their pill before it is placed on the market. In order to determine the dissolving characteristics, dissolution test equipment is utilized. Although dissolution test equipment is commonly used in conjunction with drugs designed for human consumption, it is considered to be within the scope of this invention to use it with other animals such as horses, cows, rabbits, cats, dogs, monkeys and so forth.
Every form of dissolution test equipment generally utilizes a plurality of liquid containing flasks called testing vessels. In each flask is to be placed a liquid called media, with this media essentially duplicating the liquid solution that is contained within the stomach of the human body. The precise quantity of the solution is placed within the flask. The pill is then inserted into the flask and the time of the insertion then noted. A mixing paddle is inserted within the flask with mixing at a precise rate then occurring. The mixing procedure is to duplicate the natural turbulence that is created within the stomach of the human. Aliquots are removed from the solution at precise time intervals with these aliquots then being analyzed to determine the amount of drug that has been dissolved within the solution in relation to the time that the pill has been in the solution.
In order to insure that the testing process is accomplished as accurate and quickly as possible, such dissolution testing apparatus, in the past, has been designed as follows:
1. Normally the dissolution testing apparatus would have six or eight flasks. Dissolution testing of the pill is accomplished simultaneously in all six or eight flasks with each flask to receive a pill. The average dissolving rate is then calculated between the flasks.
2. The flasks are placed in a bath with this bath to be maintained at a precise temperature. The temperature level is to essentially duplicate the temperature of the stomach liquid within the human.
In the past, the procedure in conjunction with the six or eight flasks is for the technician to remove the media from each individual flask and place it within a collecting vessel. A precise quantity of the media is to be removed and placed within the vessel. At times, it is then required to replace that precise same quantity of raw media back into the flask from which the media has been removed. Also, at other times the media that is being tested is to be reinserted back into the flask. Previously, this tedious procedure of removal of aliquots and replacement of the aliquots or media back into the flask has all been accomplished manually. Inherently, inaccuracies develop. Also because of the time it takes to complete the manual removal procedure, additional inaccuracies develop because what is being calculated is the amount of dissolution of drug within the media within a certain period of time and the removal and replacement procedure takes. time which affects the accuracy of the readings.
The dissolution sampling apparatus of the present invention is designed to automatically extract samples (aliquots) from multiple flasks that contain media and deposit these aliquots within collecting vials with each aliquot being deposited in a separate collecting vial. The sampling apparatus of this invention can also resupply the aliquot that has been removed back to the flask from which the sample has been taken or the sample can actually be discarded as waste. When discarded as waste, an additional quantity of the raw media liquid can be resupplied to the flask from which the sample has been taken. The present invention is to be used in conjunction with a dissolution test apparatus such is as shown and described within U.S. Pat. No. 5,639,974 which issued on Jun. 17, 1997. However, the present invention can be effectively interfaced with numerous other types of dissolution test apparatus and it is not intended to be solely used with the dissolution test apparatus of the aforementioned patent. However, all dissolution test apparatuses use a multitude, usually six to eight in number, of flasks with the media that is to be removed from each of these flasks. Within each flask is deposited a pill and the flask will normally include a mixing device which is to be used to create a turbulent action within each flask essentially duplicating the. turbulent action that is naturally created within the human stomach. The definition of pill is to also include capsules and caplets or any type of device which is to dissolve.
The present invention can comprise two different models with both models utilizing a plurality of piston operating devices which we refer to as syringes. There is to be a syringe for each vessel that contains media. Each syringe includes a body that is basically hollow within which is mounted a piston. This piston is retractable and expandable within the body. This retraction and expansion is accomplished by means of a motor which is precisely controlled by software. Associated with each syringe are a plurality of valves. Each valve is also operated by the software as to whether the valve is opened or closed. The first model is referred to as the DISSOSCAN and the-second model is referred to as the MAXIMIZER. The DISSOSCAN utilizes a single three-way solenoid valve that are mounted in conjunction with each syringe. The MAXIMIZER utilizes four two-way solenoid valves operated to accomplish the valving in conjunction with each syringe. The MAXIMIZER model is designed to be more versatile than the DISSOSCAN model with the MAXIMIZER able to perform a greater number of functions. However, the MAXIMIZER model has a disadvantage in that it is inherently more expensive.


This invention proposes a method for securing updating software in a plurality of decoders based on the generation of a signature by means of a private asymmetrical key. The updating of a decoder is carried out by downloading, from a managing center, a data block including a patch and its signature, said block is stored in a RAM. The signature is decrypted with a current public key from a list contained in a first non-volatile memory of the decoder, then verified and in the case of correspondence, a command leads the installation of the patch in a second non-volatile Flash memory and the deactivation of the current key. The aim of this invention is to considerably reduce the impact of the discovery of a private key by mean of a systematic analysis of the working of the decoder software, or to notably increase the time and the means necessary for the process used to determine said private key.

This invention concerns a method for securing processing software updates ensuring the working of various systems. In particular, the method of this invention uses a numerical signature mechanism with a private key of an asymmetrical encryption algorithm.
A system is defined here as an apparatus or a set of apparatuses which functioning depends on one or several software programs stored in a non-volatile memory or on a hard disk. When the functionality of the system must be improved or completed in order to adapt to the increasing demands of the user, it is often necessary to only update the related software without therefore having to change all the material making up the system.
In general, updating a given software is carried out by replacing software files already installed or by adding new files for completing those which are already stored. The assembly thus constitutes a new version of the software previously installed in the system that benefits in this way from the desired improvements.
Various apparatuses such as computers and their peripheral equipment, vending machines, fixed and mobile phones, Pay-TV decoders, etc. are controlled by software programs adapted to their configuration and to the functions of specific components.
For example, in a Pay-TV decoder (Set Top Box), processing software controls peripheral equipment such as a hard disk, a chip card reader, data reception interfaces and memories. In order to introduce changes either at the configuration level or at functionality level, it is sometimes necessary to replace the existing software or to introduce improvements to that which is already installed in the decoder. This type of improvement takes place by means of software portions, called updates or patches, provided by the operator's managing center, to which a certain number of users are subscribed. These updates are regularly provided by the managing center and are downloaded into the decoders of each subscriber possessing the necessary rights.
The document WO98/43431 describes a method for downloading applications into a receiver/decoder. The application software is divided into modules and the downloading of the modules is preceded by a search of a directory module at a determined local address. The modules are signed and the directory module is signed and encrypted in such a way that a single encryption is applied to all the modules forming the application. Several public encryption keys are stored in a read only memory (ROM) of the receiver/decoder. The applications can thus be created by means of different sources without the knowledge of each of their private keys being required. A directory signature can be concealed in a variable position in an arbitrary data block of the directory module. An application to be downloaded can be verified by making a comparison with an application validation bitmap stored in the receiver/decoder.
The document WO01/35670 describes an information authentication method transmitted to a Pay-TV decoder. A software object and a separated data structure containing the authorization data are numerically signed with a global signature that covers both objects. These objects are transmitted separately to the decoder. Once the decoder has received these objects, the signature is verified. In general, decoder users have a subscription contract with an operator that guarantees a regular maintenance service for the software installed in the decoder. In order to limit misuse such as unauthorized copies and the introduction of foreign software components, it is essential to secure the software updating of the decoder. A known method consists in using a digest coded with an asymmetrical encryption algorithm key of the RSA type. The updating software is provided on-line with a digest obtained by means of a unidirectional hash function. This digest is made up of a single image representing the whole updating and it is assumed that two identical digests never exist on two identical assemblies with different data. This digest is encrypted thanks to an operator's private key associated to a group of subscribers, which constitutes a signature specific to this group. The software accompanied by this signature is loaded in a RAM (Random Access Memory) of the decoder. A program belonging to the decoder software calculates a digest of the software stored in the RAM with the hash function. The received signature is decrypted with a public key contained in the decoder and is then compared to the software digest calculated previously. If the decrypted signature corresponds to the digest obtained by means of the hash function, the signature accompanying the update stored in the RAM will be considered as valid. The updating software will be installed in the non-volatile memory of the decoder (Flash memory).
The securing process is thus carried out by means of the verification of the signature with a public key in the decoder which corresponds to the operator's private key.
The public key present in the decoder as well as the program allowing signature verification must be fixed. The authenticity of the signature is guaranteed owing to the fact that the private key depends on the decoder's public key. The signature cannot be reproduced because the private key is only known by a given operator. Furthermore, the same signature is useless for various different updates since it is a function of a well-defined updating. A signed updating software whose content is modified in the RAM will produce another digest which cannot thus be validated by the signature decrypted by the public key. In fact, the digest obtained after the hashing of the updating software at the level of the decoder is different to that obtained after decrypting the signature.
However, this securing method includes a weak point consisting in the operator's private key itself. In fact, when said key is discovered by a third party, it can sign any software and lead to abusive modifications of the system.
This discovery can be made by means of iteration on the public key that the third party has extracted from the decoder until the correct pair of keys are discovered. The counter-measure, that consists in modifying the behavior of the decoder software so that it refuses the signatures generated with the discovered key, is insufficient since these modifications can be avoided by the third party by using suitable programs.
The aim of this invention is to considerably reduce the impact of the discovery of a private key by mean of a systematic analysis of the working of the decoder software, or to notably increase the time and the means necessary for the process used to determine said private key.
The aim is achieved by means of a securing method for data updating in a plurality of apparatuses, each apparatus receiving the updates from a managing center, these updates including data called patch accompanied by a control block encrypted by a private asymmetrical key taken from a list of keys contained in the managing center, characterized by the following steps:                selection by the apparatus of a current key from a list of public keys,        reception of the updating patch and storage in the memory,        reception of the encrypted control block,        decryption of said block by the current public key,        verification that the decrypted control block corresponds to said patch,        installation of the patch received,        deactivation of the current key and selection of the next key on the list.
The data of an update is transmitted by the managing center in the form of a patch and a control block including a signature made up by the digest of the patch encrypted with a private key from the managing center. The decoder stores this data in the RAM memory for processing. A public key, associated to this private key, called the current key, is selected from a list stored in a first non-volatile memory in order to decrypt the patch signature. In the case that decryption and verification are successful, a command is carried out leading to the installation of the patch in a second non-volatile memory (Flash) of the decoder. The current key used in this way is deactivated on the list, which makes the following key available for the next update.
When the verification of the signature and the decryption of a decoder update is carried out with a public key from the list, said key is deleted and cannot be used for further updates. Thus, a new key is used for each update and is then eliminated from the list. The public key from the list as well as the program serving to verify the signatures must be non-modifiable. Only the list can be modified (elimination of used keys) with the verification program.
The above-described method allows a considerable reduction of the possibilities of decoder modifications by a third party having discovered a private key. Since a key can only be used once, the third party will only carry out a single modification. Consequently, a modification of decoder behavior in order to protect it from piracy is more effective since the third party, no longer in possession of a valid private key, is unable to access the apparatus.
Due to the fact that the number of private keys is larger, a third party must therefore systematically activate all the keys to avoid to be blocked at the update corresponding to the discovered key. It is necessary to know that the development of the decoders' software is fast and considering that if one of the keys is discovered the following updates will fill the security gap that the third party would have been able to introduce. If this third party is able to block all subsequent updates, the functionalities of the decoder will rapidly become obsolete and therefore without any important prejudice to the operator.
The use of asymmetric keys is important in this context since the extraction of public keys from a decoder does not allow the implementation of an acceptable update because said update must be signed by the operator's private key. It is common to place the private keys in the secured part (the operator) and the public keys in the public domain part (the decoder). Nevertheless, it is possible to invert the keys without damaging the functioning of the present invention.
A first embodiment of the invention proposes the use of public keys taken from the list according to a pre-determined order. Therefore, each key is taken from the list as soon as the previous key has been used.
In the example disclosed in FIG. 1, an initial version decoder is updated to the version 1 with a patch P1. This patch P1 is transmitted with its signature (H(P1))PK1 by the operator's managing center towards the decoder. The updating process begins by the loading of the patch P1 into the RAM of the decoder.
The signature (H(P1))PK1 is obtained by the encryption of the digest H(P1) of the patch P1 with the private key PK1 of the operator, this operation being carried out in the managing center. This digest is calculated by the operator from the patch P1 with a unidirectional hash type function H.
The decoder software decrypts the received signature (H(P1))PK1 with a public key K1 in order to obtain the digest of the patch H(P1)1. Simultaneously, this same software calculates the digest H(P1)2 of the patch P1 stored in the RAM. The first digest issued from the decryption of the signature H(P1)1 and the second H(P1)2 resulting from the calculation by means of the hash function H are compared. If the two values correspond, the patch P1 is installed in the decoder's non-volatile Flash memory FH in order to carry out the updating of the decoder software. The public key K1 used to decrypt the signature is deleted from the list.
A second update of version 1 to version 2 transmitted by the managing center in the form of a new patch P2 accompanied by its signature (H(P2))PK2 passes through the same downloading and verification process. A new public key K2 taken from the list will then be used by the decoder. All the following transmitted updates are verified in the same way using each time a new public key taken from the list. The previous updating keys are neutralized either by deletion or by a suitable marking.
By applying this process, a software update from version 1 to version N is carried out in N−1 steps. The managing center will transmit N−1 patches with corresponding N−1 signatures each encrypted by a private key specific for each version. The installation of the different patches thus leads to the neutralization of N−1 public keys from the list.
The list of public keys can be stored, for example, in a non-volatile memory of the type EEPROM (Electrically Erasable Programmable Read-Only Memory). After each use of a key during an update, said key is definitively deleted from the EEPROM authorizing the access to the following key for the next update.
According to another embodiment, the list of public keys is not altered by the deletion or marking of a key. After each installation of a software version in the non-volatile Flash memory, a counter is incremented or a pointer moves to indicate the position of the key to be selected from the list during the next update. Therefore, at each update, only the key which will serve to decrypt the signature of the patch is designated, the previous keys no longer being available for selection because the counter or the pointer can only progress in one direction, that of increasing positions.
According to a variant, the patch can be encrypted by the private key of the operator. A supplementary decryption step is thus added to the above-described process. The patch P received and loaded into the RAM can be decrypted with the public key before the calculation with the hash function H of the digest serving as signature verification. The calculation of the digest can also be carried out on the patches in its encrypted form.
Update installation by a third party is made more difficult by the fact that each version change requires knowledge of the current key. The latter changes at each update, which obliges the third party to know all the keys in order to follow the different updates.
The previously described process can occur a problem when the decoder has remained out of service during a time in which several updates should have been carried out. The passing of an old software version to a new version whose number is not consecutive to that of the previous version is carried out sequentially in several successive steps. The said steps use different public keys taken from the list one after the other and in a consecutive order. It is reminded that the patch itself does not contain a command that allows the selection of a key other than the current key. If it is the case, a third party could use this command to force the use of a key known to said third party.
FIG. 2 shows the case of the passing from a software version N to a version R where the difference R-N between the new version and the previous version is greater than one. The following example refers to a case where N=2 and R=5.
A decoder with version 2 software cannot directly decrypt the signature (H(P))PK5 of the new version 5 because the key available in the list of public keys is that of the version immediately higher, namely the key K3. For the installation of the new version 5, the decoder must be able to gain access to the key corresponding to this version, that is to say the key K5.
The solution consists in transmitting a data flow containing the patch P for updating the software of the decoder to version 5 signed with the key PK5 to which a plurality of messages M1, M2, M3, M4 are added, each encrypted with a private key PK1, PK2, PK3, PK4 taken from the key list. The RAM memory stores these messages as well as the patch P with its signature (H(P))PK5. The version of the decoder being 2, the updating key of version 1 to 2 is already deactivated by the first update. The message M1 is then ignored because the key K1, that serves to decrypt it, is no longer available.
The following messages M2, M3 and M4 are used to consecutively deactivate the public keys K2, K3, and K4 that correspond to each intermediate version from version 2 to version 4 preceding version 5. Therefore, to install version 5 in the non-volatile Flash memory, each public key K2, K3, and K4 of the list is used then neutralized or deleted. During the decryption of the message by the correct key, the content of this message is recognized and induces the neutralization operation of the current key. If the message is not recognized, this means that the encryption key of this message is not the current key.
After the successive and correct decryption of the messages M2, M3, M4, the key K5 necessary for the decryption of the signature of the patch (H(P))PK5 (and of patch P) becomes the current key. The latter will also be deleted from the list after the installation of the patch and the key K6 will be present at the head of list for the subsequent update of version 5 to version 6.
This type of flow can thus update an entire group of decoders regardless of their software version thanks to the key change messages that accompany the patch. Each decoder disposes of a public key in the list able to decrypt an update of the current version after the neutralization of the old keys.
During a decoder software update of version N to a version R where the difference R−N becomes large, for example over 10, it becomes tedious for a decoder with version R−1 to systematically decrypt all the messages in order to verify the deactivation orders. This decoder will apply its current key (R−1) to all of these messages to notice that it is unable to interpret its contents.
A first solution consists in introducing in the message header indexes in clear that correspond to the numbers of the different versions. This index only serves to avoid the decryption of messages that have been encrypted by a key other than the current key. This index does not select the position of the current key, only the successful decryption of a message with said current key induces the advance of one position in the keys list.
According to a second solution, the digest of the updating patch is successively encrypted by all the private keys of the previous updates. This process obliges the use of each public key on the list, consecutively, to decrypt the signature. In this case of encryption in chain, unlike in the previous case, all the public keys must remain available in the EEPROM of the decoder. For example, for an update of version 1 to version N, the digest of the patch P is encrypted with a private key of version N. The whole set is then encrypted with the private key of version N−1, then with the key of version N−2 and so on until the version 1. The decryption thus requires the successive use of public keys K1 to KN−1 corresponding to the updates of version 1 to version N. The interruption of this iterative mechanism is enabled by means of the recognition of a suitable mark in the decryption result.
If one wishes to protect the update data, one method consists in the use of a session key SK randomly generated by the managing center for example. For reasons of operation speed, this key is of a symmetrical type. The managing center encrypts the patch with the session key SK and composes a data set that includes the session key SK and the digest of the updating patch. This set is encrypted by the current private key of the operator to make up the control block.
The encrypted patch and the control block are loaded into the RAM memory of the decoder. The block is decrypted by the current public key on the list, which provides the patch digest and the session key SK. The latter is applied to the patch loaded in the RAM thus allowing its decryption. Then, the patch digest is verified and in the case of correspondence the patch is installed in the non-volatile Flash memory.
The session key can be introduced as a supplementary securing mean in any of the variants described above, for example:                the simple update of version 1 to version N in several steps,        the updating of version N to R with a patch and key deactivation messages.
In a decoder that has been updated several times, the number of available public keys decreases while the number of deactivated keys increases with the successful updates. In order to rebuild a list of keys to allow future updates, a new public key list can be sent to the decoder by the managing center. This list can be incorporated into the data, flow and accompanied by a signature as in the case of an updating patch. Said list is stored in the EEPROM and replaces the old list containing the deactivated keys.
According to a variant of the method of the invention, the managing center and the decoders dispose respectively of a fixed private and public key list. For each update, the managing center randomly selects a private key set from those on the list and encrypts the patch digest successively with each key of the set. The center creates a data block that includes the encrypted digest (signature) and a series of numbers corresponding to the positions of the previously chosen keys. Said series can be transmitted in clear or encrypted with a session key. The decoder receiving said series selects from the list of public keys, according to their position, the keys necessary to decrypt the patch digest. The list cannot include the same key number more than once and the length of this list (number of keys used) is known and non-modifiable. In this variant, the lists of keys remain fixed and are not altered after a successful patch installation. At each update, a new key combination taken from the list is used for the patch signature. Therefore, a third party must always dispose of a set of keys in order to introduce an update into an apparatus, which requires more important means than the means required to determine a single key.
The update securing process according to the invention is independent of the transmission mode used between a supplier and a user. In fact, the process can also be applied to patches distributed on CD-ROM, on disks or on any other digital data storage medium.


A process for forming a porous silicon nitride-silicon carbide body, the process comprising (a) forming a plasticizable batch mixture comprising (1) powdered silicon metal; (2) a silicon-containing source selected from the group consisting of silicon carbide, silicon nitride and mixtures thereof; (3) a water soluble crosslinking thermoset resin having a viscosity of about 50-300 centipoise; and, (4) a water soluble thermoplastic temporary binder; (b) shaping the plasticizable batch mixture to form a green body; (c) drying the green body; (d) firing the green body in nitrogen at a temperature of 1400xc2x0 C. to 1600xc2x0 C. for a time sufficient to obtain a silicon nitride-silicon carbide structure.

The present invention relates to a method of making silicon nitride-bonded silicon carbide honeycomb bodies useful in the removal of diesel soot particles from the exhaust gas of diesel engines.
Filters of diesel exhaust streams require a combination of high thermal shock resistance, chemical and mechanical durability in harsh environments, and good filtration efficiency.
Silicon nitride-bonded silicon carbide is known for being highly refractory material and therefore would be suitable in applications for the treatment of diesel exhaust, such as diesel particulate filters. In general, the method for forming such composite material is via the formation of a green body from of mixture of powdered silicon carbide and powdered silicon nitride, the green body being thereafter sintered. The drawback of this process is a non-uniform microstructure in the final product. In diesel filtration applications such a non-uniform microstructure could harbor local stresses which may lead to thermal cracking and failure during use.
There is, accordingly a clear need for, and thus an object of the present invention to provide for a process for making silicon nitride-silicon carbide composite material for diesel exhaust filtration applications.
Accordingly, the object of the present invention is directed at a plasticizable raw material batch mixture for forming a silicon nitride-silicon carbide honeycomb structure for diesel exhaust filtration, comprising the following components: (1) powdered silicon metal; (2) a silicon-containing source selected from the group consisting of silicon carbide, silicon nitride and mixtures thereof; (3) a water soluble crosslinking thermoset resin having a viscosity of about 50-300 centipoise (cp); and, (4) a water soluble thermoplastic temporary binder. Optionally, the batch mixture can include a pore forming filler comprising either a graphitic or a thermoplastic pore-forming filler, such as polyethylene beads. The silicon nitride-forming source can include silicon metal and
The inventive process further involves the following steps: (1) mixing together selected raw materials to form the previously mentioned plasticizable raw material batch; (2) shaping the batch mixture to form a shaped green body, preferably involving extrusion to form a honeycomb structure; (3) drying and curing the green body; (4) firing the green body in nitrogen at a temperature sufficient to convert the green body to a porous silicon nitride-silicon carbide sintered body; preferably a temperature of about 1400-1600xc2x0 C.
The present invention relates to a method of making silicon nitride-silicon carbide honeycomb bodies which possess good mechanical strength, uniform pore structure and desirable properties especially for diesel particulate filtering applications.
The extrudable batch mixture for use in preparing a silicon nitride-silicon carbide honeycomb substrate includes powdered silicon metal, a silicon-containing source selected from the group consisting of silicon carbide, silicon nitride and mixtures thereof and a thermoset resin.
Advantageously the batch may include about 20-50%, by weight, powdered silicon metal; preferably about 35%; (b) about 10-35%, by weight, powdered silicon nitride; preferably, about 15-30%; and (c) about 10-25%, by weight powdered silicon carbide. The silicon metal should exhibit a small mean particle size of about 10 to 20 micrometers, preferably about 15 micrometers. The mean particle size of the silicon nitride powder should be about 5 to 40 micrometers, preferably about 10 micrometers. The mean particle size of the silicon carbide powder should be about 5 to 20 micrometers.
It is preferred that the silicon powder be comprised of a crystalline silicon powder. It has been found that the use of amorphous silicon metal powder in the subsequent formation process results in an aqueous system that typically is subject to a reaction, and resultant foaming, between the silicon and water which is used as the preferred solvent for the thermoset resin batch component as discussed below. This foaming is particularly undesirable when forming honeycomb, or similar-type filtration structures, as it makes it particularly difficult to form structures exhibiting controlled wall uniformity, porosity and microstructure; i.e., difficulty in forming ceramic bodies exhibiting the narrowed pore size distribution desired for filtration applications.
The raw batch also contains about 5-30%, by weight, of a thermoset resin, specifically a water soluble crosslinking thermoset resin. Acceptable water-soluble crosslinking thermoset resins include phenolic resins, such as Phenolic resole liquid resin available from Georgia Pacific commercially sold as code GP510D34 RESI-SET.
Viscosity is an important feature of the thermoset resin utilized in the raw batch. It has been discovered that resin systems, in addition to being water-soluble must have a viscosity of about 50-300 centipoise (cp). Viscosities at these low levels allow the plasticized batch mixture to be extrudable in a variety of shapes, specifically honeycombs. Use of a thermoset resin of higher viscosities results in extruded structures, such as honeycombs, that have a tendency to exhibit split walls, in spite of attempts to avoid this undesirable split wall feature by adding water to reduce the viscosity of the resin. Although not intending to be limited by theory, it is thought that the reason for this behavior is as follows. Phenolic resins are produced by a reaction of phenol and formaldehyde in a water solution while in the presence of an acid or base catalyst. As the reaction proceeds, oligomers are formed and the resin begins to precipitate. The longer the reaction is allowed to continue, the higher the oligomer molecular weight. Higher molecular weight oligomers have fewer reactive sites and lower water solubility. The viscosity of the resin thus indicates its oligomer reactivity and water solubility. Once the viscosity becomes very high, the resin completely precipitates out of the water. For a given process the viscosity of the phenolic resin is thus very critical, since it will determine the reactivity of the resin with components, it""s capability to be diluted and still form strong structure on cure, as well as carbonization tendency. In this particular case where phenolic resin-containing honeycomb structures with fillers are preferably extruded, it is necessary to have the resin viscosity between 50-300 cp. One advantage of utilizing the liquid thermoset resin in the batch mixture is that it intimately mixes with silicon powder to ultimately form a homogeneously and intimately mixed structure.
About 5-10%, by weight of a water-soluble thermoplastic temporary binder is added to the mixture to obtain a good extrudate. Acceptable temporary binders include methylcellulose, hydroxypropyl methylcellulose, and combinations thereof. Preferred sources of cellulose ethers and/or derivatives thereof, are Methocel A4M, F4M, and F240M from Dow Chemical Co. Methocel A4M is a methylcellulose binder having a gel temperature of 50-55xc2x0 C. and gel strength of 5000 g/cm2 (based on 2% solution at 65xc2x0 C.). Methocel F4M and F240M are hydroxypropyl methylcellulose.
Optionally, the batch may include a pore-forming filler in an amount of up to 20%, by weight, specifically an organic filler, which does not leave any carbon residue after firing; suitable pore-formed fillers include either a graphitic or thermoplastic pore-forming filler. Pore size and porosity amounts are important properties that must be controlled when forming a honeycomb structure for use in filtration applications. For applications such as diesel particulate filtration, for example, desired pore sizes range from 3-30 microns. If a graphitic pore-forming filler is utilized in the batch mixture, the mean particle size and weight percent of graphite powder utilized determines the final porosity in the wall. It should be noted that the graphitic filler is not affected in any way during later-described cure, carbonization or reactive firing/sintering of the honeycomb structures. As such, any so-formed structure will require a post-sintering step to burn out graphite and leave porosity behind; e.g., the honeycombs can subjected to air firing at around 800xc2x0 C. to burn out graphite. On the other hand, the use of a thermoplastic pore-forming filler will not require a post-sintering burn-out step as the filler burns out in nitrogen during the later-described carbonization with little or no carbon residue while still leaving behind the requisite porosity.
The mixing preferably takes place in three stages. In the first stage, the silicon nitride and silicon carbide sources are mixed with the required amount of the water-soluble resin. The second stage or wetting stage of batch formation, involves adding and dry mixing together the resin mixture and the remaining powder particles, i.e., the binder and optional pore former, and thereafter adding the required amount of the solvent to form the wet batch. This mixing and solvent addition is done in a standard mixer, for example a Littleford mixer. The solvent, typically water, is added in an amount that is less than is needed to plasticize the batch; typically the water is added as a superaddition, in amounts ranging from 5-25%, by weight, with levels ranging from 7-15%, by weight being preferred. With water as the solvent, the water hydrates the binder and the powder particles. At this stage, the powder particles are coated and dispersed.
In a preferred embodiment, the plasticization takes place in the third stage. In this stage the wet mix from the second stage is sheared in any suitable mixer (e.g., Littleford) in which the batch will be plasticized. In other words, stirring together the powdered components, in a suitable known manner, to prepare an intimate mixture capable of being formed into a green body by, for example, by extrusion or molding.
Following plasticization, the resulting stiff, uniform and extrudable batch mixture is then shaped into a green body by any known conventional ceramic forming process, such as, e.g., extrusion, injection molding, slip casting, centrifugal casting, pressure casting, dry pressing, etc. For the preparation of a thin-walled honeycomb substrate suitable for use in diesel filtration applications, extrusion through a die is preferable.
Once the batch mixture is plasticized and thereafter shaped into, for example a honeycomb structure, the so-formed structure is then dried and cured by one of a variety of conventional techniques known to those skilled in the art, e.g., hot-air heating, microwave heating, and dielectric heating. Preferably, the green honeycomb structures are dried and cured for a period of 1 hour at temperatures of up between 90 to 150xc2x0 C.
The green structures are then fired in nitrogen at temperatures of between 1400-1600xc2x0 C. to carbonize the resin and to remove pore-forming fillers. The green structure should be fired for a sufficient period of time so as to complete the conversion to silicon nitride-silicon carbide porous honeycombs. The firing step can be carried out in a conventional batch or continuous furnace, wherein the shaped body is passed through the hot zone of the furnace at a rate to provide a prescribed residence time at the desired temperature.

Method of making silicon nitride-silicon carbide composite filters


A flexible carrier for carrying a plurality of containers includes a flexible sheet and a plurality of container receiving apertures formed in the flexible sheet together with a system and method of application including an applicating machine for applying the flexible carrier to a plurality of containers provided from an infeed includes a jaw assembly that reciprocates to apply a generally continuous string of carrier stock onto a quantity of containers.

1. Field of the Invention
This invention relates to a flexible carrier for carrying a plurality of containers such as bottles or cans and a system for applying the same.
2. Description of Prior Art
Container carriers connect two or more containers into a sturdy unitized package of containers. Carriers are generally planar arrays of rings, sometimes referred to as six-pack carriers, typically formed from a thermoplastic sheet material. Carriers are applied to containers of various sizes and shapes along various points along the sidewall or under the chime of the container.
Conventional carriers are arranged in aligned arrays of longitudinal rows and transverse ranks of container receiving apertures. A common arrangement is two rows of three ranks of longitudinally and transversely aligned container receiving apertures forming six total container receiving apertures and a "six-pack." Other common configurations include two rows of four ranks forming an eight container multipackage and three rows of four ranks forming a twelve container multipackage.
Conventional applicating machines include a circular jaw drum used to apply carriers to individual containers. The conventional jaw drum is typically fixed into position on the applicating machine and fed with a reel or box of a generally continuous container carriers. Such conventional applicating machines typically include an infeed conveyor for supplying a plurality of containers. Additionally, a reel stand is positioned upstream of the jaw drum to supply a reel of carriers to a feed drum and then on to the jaw drum.
The string of carriers are then traditionally applied to the containers and, following application, cut into a desired package configuration. The resulting package is then fed into a turner-diverter that moves and/or rotates the package to a correct position for placement on a pallet or similar shipping unit.

Flexible carrier and system for application to a plurality of containers


A method for avoiding loops from forming when setting up label switched paths is provided. The method uses a Label Splicing Message is followed by an Acknowledgment message to determine if loops are formed in the process of joining a new node or subtree to a multicast MPLS tree. By verifying that the path towards the root of the MPLS tree is loop-free during the construction of the tree, this method complements the loop detection mechanism provided by the label switched protocol (LDP).

1. Field of Invention
The present invention relates in general to digital communication methods and systems, and in particular to a system and method for preventing the formation of loops in label switched paths in a multi-protocol label switching (MPLS) communications environment.
2. Related Art
A host node initiating a transmission of a data packet to another node in the network is called the source node. The host node which receives the data packet is called the destination node. A host node may initiate transmission or receive data, whereas a router can only receive and retransmit data. Establishing communications between a single source node and a single destination node is achieved through a process called unicast routing.
Multicasting is defined as a communications process involving one or more senders and receivers. Information transmitted by any participant in the multicast is received by every other participant in the multicast. Users connected to the network who are not participants in a particular multicast do not receive the information transmitted by any of the senders and no network components, e.g. switches or trunks, are used unless needed for the multicast. For example, broadcast involving one sender and many receivers is a particular case of multicasting and may include wide-area broadcast, e.g. TV and radio, narrowcast for smaller areas, and conferencing with selected numbers of transmitters and receivers across a wide area.
For performing a multicast conversation in a network, the switches elect a single switch among all the switches within each network to be the "root" switch. Each switch has a unique identifier (switch ID) and the root may be be the switch having the lowest switch ID. At each switch, a "root port" which gives the fewest number of hops from this switch to the root is selected, while ports not included within the spanning tree are blocked. At the root, all ports are placed in the forwarding state. For each LAN coupled to more than one switch, a "designated" switch, typically the one closest to the root, is elected to ensure connectivity to all LANS.
A standard spanning tree procedure has been defined for network bridging devices (bridges, routers, switches) to enable these devices to discover a subset of any topology that forms a loop-free (i.e. tree) and yet connects every pair of local area networks (LANs) within the network (i.e. spanning). The spanning tree procedure results in a network path between any two bridging devices which is updated dynamically in response to network modifications. For example, switches exchange configuration messages called bridge protocol data units (BPDUs) frames, which allow them to calculate the active topology, or the spanning tree by blocking all redundant links and leaving a single communications path.
A plurality of switches interconnected by trunks may be arranged to form a spanning tree (MDT) or a multicast distribution tree. If host nodes A and B wish to set up a multicast transmission using a previously agreed multicast address "M", a control packet containing source address "A" and destination address "M" is transmitted in the network. Entries are added at each switch where the control packet arrives and then deleted after the defined time interval (MaxTime) if the entries are not reinforced from hosts A and B. When another host wants to join a multicast transmission, even if it is the first participant, it simply transmits a JOIN request control packet from itself to the "M" address. The JOIN request is broadcasted over the entire spanning tree and the joining host continues to send packets to the "M" address with a maximum inter-packet time interval smaller than MaxTime to make sure that at least one of the relevant table entires is not cleared.
A new branch in a multicast distribution tree (MDT) tree is formed by transmitting a JOIN REQUEST control packet from a node, or a subtree that wishes to join the group. The multicast tree sends back a JOIN ACKNOWLEDGMENT (JOIN-Ack) control packet in the opposite direction. It is possible to transmit only the JOIN request and each node not already in the multicast tree which receives the JOIN request is directly attached to the tree. However, the use of JOIN-Ack provides some ability to prevent loops from occurring.
A loop is a circular path which causes a packet to return to originating node on the same path the packet was transmitted. The existence of redundant communications paths, especially in meshed networks, may cause the undesirable formation of "loops" resulting in proliferation of data frames along loops. As well, the expansion of networks often results in loops that cause undesired duplication and transmission of network packets, such as broadcast storm as well as address conflict problems.
When a node attempts to re-join the group, the node generates a JOIN request control packet with a set active flag and a set re-join flag. When this packet is received at a member node, the receiving node clears the active flag and transmits a JOIN-Ack back to the node which generated the JOIN request, and retransmits copies of the JOIN request to each member node. Member nodes receiving the copy of the JOIN request control message retransmit copies of the received JOIN request to other member nodes, except the node from which the packet was received.
If the JOIN request control packet returns to the originating node wishing to re-join, then a loop exists and includes only member nodes. The originating node has to transmit a QUIT request control packet, and reattempt to join after a preset waiting period.
It is desired to detect problematic links or loops that can cause problems and undermine the purpose of the spanning tree. Generally, most unicast algorithms provide for loop prevention when forming unicast routing paths between each node and storing these paths in the forwarding tables. When a loop is created, the unicast algorithms detects and removes such loop by revising the paths contained in these loops. Even transient loops can disrupt the construction of the multicast distribution tree (MDT).
As internet communications increase, it has become apparent that competing network layer protocols, such as the Internet Protocol (IP), Asynchronous Transfer Mode (ATM) and Frame Relay (FR), need to interoperate to forward packets. The Multi-Protocol Label Switching (MPLS) has been developed to work with any network layer protocol.
Under a conventional connectionless network layer protocol such as IP, a data packet is forwarded from one router to another as the data packet travels from its start to its destination. As the data packet is forwarded, each router makes an independent forwarding decision for that data packet by analyzing the packet's header and running a network layer routing algorithm. Each router then independently chooses a next hop for the data packet, based on its analysis of the packet's header and the results of the running routing algorithm. To choose the next hop for a data packet Involves two steps. The data packets are first partitioned into forwarding equivalence classes (FECs). Secondly, each forwarding equivalence class is mapped to a next hop.
As far as the forwarding decision is concerned, different data packets that are partitioned into the same FEC are indistinguishable, and all data packets that belong to a particular FEC and traveling from a node, follow the same path (or one of the set of paths) associated with this particular forwarding equivalence class (FEC).
A typical router considers two data packets to be in the same forwarding equivalence class (FEC) if there is an address prefix in that router's routing tables that is the longest match for each data packet's destination address. As the data packet traverses the network, each hop in turn reexamines the packet and assigns it to a forwarding equivalence class (FEC).
By contrast, in multi-protocol label switching MPLS the assignment of a data packet to a particular forwarding equivalence class (FEC) is done just once when the packet enters the network. The FEC to which the data packet is assigned is encoded as a short, fixed length value known as label.
When a data packet is forwarded to its next hop, the label is sent along with it. Thus, the packets are "labeled" before they are forwarded. At subsequent hops, there is no further analysis of the packet's network layer header. Instead, the label is used as an index into a table that specifies the next hop, and the new label to be assigned. The old label is replaced with the new label, and the packet is forwarded to the next hop. A router that supports multi-protocol label switching is known as a label switching router (LSR).
The multi-protocol label switching (MPLS) has a number of advantages over conventional network layer forwarding protocols. First, MPLS forwarding can be done by switches that are capable of doing label lookup and label replacement, but are either not capable of analyzing the network layer headers, or are not capable of analyzing the network layer headers at adequate speed.
Secondly, since a data packet is assigned to a FEC when it enters the network, an ingress router can use any information it has about the packet to determine the assignment, even if that information can not be determined from the network layer header. For example, data packets arriving on different ports can be assigned to different forwarding equivalence classes (FECs).
In MPLS, a data packet that enters the network at a particular router can be labelled differently than the same packet entering the network at a different router. As a result, forwarding decisions that depend on the ingress router can be easily made. This functionality can not be achieved with conventional forwarding, since the identity of a data packet's ingress router does not travel with the packet. (Conventional forwarding can only consider information that travels with the packet in the packet header).
Finally, for purposes of traffic engineering, it is sometimes desirable to force a packet to follow a constraint route which may be explicitly chosen at or before the time the packet enters the network. In conventional forwarding, this requires that the packet carry a source routing. In MPLS, a label can be used to represent the route, so that the identity of the explicit route need not be earned with the packet.
A disadvantage of the MPLS is the possible creation of loops, due to independent labeling decisions made at each router. Loops can cause severe degradation of a label switched router (LSR) overall performance. Generally, loop detection procedures are used to eliminate looping label switched paths in MPLS.
One method of loop detection in multi-protocol label switching uses the time-to-live (TTL) value carried in a packets header. In conventional IP forwarding, each packet carries a TTL value in its header. Whenever a packet passes through a router, its TTL is decremented by 1. If the TTL reaches 0 before the packet has reached its destination, the packet is discarded. This provides some level of protection against forwarding loops that may exist due to misconfigurations, or due to failures, or the slow convergence of a routing algorithm. However, certain communication systems are unable to support a TTL function. For example, ATM switching hardware can not decrement TTL, thus there is no protection against looping packets.
Since there is no explicit loop avoidance mechanism in the current MPLS—label distribution protocol (LDP), data may be already looping before the loops are detected. Loops are always undesirable, and more so on a multicast distribution tree. In particular, loops in a multicast point to multipoint (p2 mp) tree are harmful, as the packets are replicated and in the event of loops, multiple copies are generated at each loop. Multicast routing loops can affect a large number of nodes in a network in a short period of time and need to be detected, and ideally prevented before network failure or a long lasting damage occur.
One method of loop avoidance has been proposed in Y. Ohba, Y. Katsube, E. Rosen, P. Doolan, "MPLS Loop Prevention Mechanism", October 1999, an IETF Internet-Draft that can be found at "draft-ietf mpis-loop-prevention-02.tx". Ohba et al. present a mechanism, based on "threads", that can be used to prevent MPLS from setting up label switched paths that contain loops. When a label switched router (LSR) finds that the next hop for a particular FEC has changed, it creates a thread and extends it downstream. Each such thread is assigned a unique "color", such that no two threads in the network can have the same color. For a given label switched path, once a thread is extended to a particular next hop, no other thread is extended to that next hop, unless there is a change in the hop count from the furthest upstream node.
The only state information that needs to be associated with the next hop for a particular label switched path is the thread color, and the hop count. If there is a loop, then some thread will arrive back at an label switched router (LSR) through which it has already passed. Such an event will be detected, since each thread has a unique color.
However, the proposed colored thread method of loop prevention has certain disadvantages. In particular, this method requires additional information especially the color to be added to the label which increases the size of each packet. Further, the loop prevention mechanism proposed by Ohba et al. does not separate the function of loop prevention from the label request message looping prevention, nor the label mapping from the label splicing function.
It is, therefore, desirable to provide method and system for preventing the creation of looping label switched paths in a MPLS environment that is reliable and requires a low router overhead.

System and method for loop avoidance in multi-protocol label switching


Vertical form fill seal apparatus for making flexible packages with slider fastener closures is provided. A fastener track is applied in-line with a plastic web and is bonded thereto at the same time that a peel seal is formed. All package components are brought together at the point of fill. Prior to assembly at the fill station a series of spaced-apart stop members are formed along the fastener tracks.

1. Field of the Invention
The present invention pertains to the manufacture of flexible packages, such as plastic bags, and in particular to packages having fastener closures employing sliders.
2. Description of the Related Art
With the recent emphasis in providing consumers with bulk quantities of various commodities, such as food products, reclosable packages have become increasingly popular. One of the most popular means of providing reclosability is to employ zippers of various types, particularly zippers which are compatible with flexible packages of plastic film construction. Manufacturers of food products and other commodities are concerned with filling the contents of a flexible package as quickly and economically as possible. It is important that the opening provided by the fastener be made as large as practically possible. Consumers or other end users also prefer large sized openings for easy extraction of products from the package interior. Even with large openings, however, products within the package may interfere with fastener operation when product poured or otherwise dispensed from the package becomes entrained in the fastener components.
Other improvements to flexible reclosable packages are being sought. For example, when handling products comprised of numerous small pieces, such as shredded cheese or cereal, for example, it is generally desirable to have the package formed into a pouch which is open at one end, or along one side, so as to allow product to be poured or shaken through the reclosable opening. It is desirable that the product be allowed to freely flow past the reclosable opening. Preferably, the path taken by the product within the package should be made as smooth as possible.
Although improvements have been made in the art of plastic welding and joining, manufacturers of consumer products employing high speed production techniques are continually seeking improved package forming methods and equipment.

Apparatus for manufacturing flexible packages having slide closures


Provided are rigid contact lenses having high oxygen permeability and methods to make the same. The rigid contact lenses comprise a polyacetylene. Also provided are methods of making rigid high oxygen permeability contact lenses.

This invention relates to contact lenses, in particular, to contact lenses having high oxygen permeability. The cornea is avascular, so the oxygen required for eye health must be transmitted from the atmosphere. If contact lenses are worn, the atmospheric oxygen transfer is blocked. Therefore, contact lenses must be oxygen permeable enough to transmit sufficient oxygen to the cornea. If sufficient oxygen is not transmitted to the cornea, comfort and eye health are affected. The highest oxygen permeability of rigid gas permeable (RGP) contact lenses is currently around 100 barrers. A RGP contact lens having higher oxygen permeability is desired.
Poly(trimethylsilylpropyne), PTMSP, was first prepared by Masuda in 1983 (ref 1). The high oxygen permeability of PTMSP was first announced in the Jan. 2, 1984 issue of Chemical and Engineering News (ref 2). PTMSP has the highest oxygen permeability of any known polymer, around 6000 barrers. This is ten times the oxygen permeability of polydimethylsiloxane, previously known as the most highly oxygen permeable polymer. Many attempts have been made to produce polymers with higher oxygen permeabilities than PTMSP, but these attempts have been unsuccessful so far.
The use of polyacetylenes including PTMSP to make contact lenses having higher oxygen permeability than current materials would be desirable, however, contact lenses from polyacetylenes are not known. Conventional methods to produce RGP contact lenses do not work for polyacetylenes. Existing RGP contact lenses are machined from polymer blanks or cast in static molds. Polyacetylenes do not lend themselves to these techniques to form contact lenses. Also, polyacetylenes are very hydrophobic and unsuitable for contact lens use directly. Existing methods to make contact lenses add wetting agents (hydrophilic monomers such as methacrylic acid, n-vinyl-2-pyrrolidone or hydroxyethyl maetacrylate) to the monomer formulation. This technique cannot be used with polyacetylenes.
A method for forming contact lenses that have high oxygen permeability from polyacetylenes is needed.

Highly oxygen permeable rigid contact lenses from polyacetylenes


A first sigma filtering circuit sigma filters an image to produce a filtered image. An analysis circuit processes the sigma filtered image to produce an approximation part and a detail part. A second sigma filter circuit filters the approximation part to produce a sigma filtered approximation part. Another analysis circuit process the sigma filtered approximation part to produce a second approximation part and a second detail part. A third sigma filter circuit sigma filters the second approximation part to produce a sigma filtered second filtered approximation part. A first synthesizer synthesizes the sigma filtered second filtered approximation part and the second detailed part to produce a first reconstructed image, and a second synthesizer synthesizes the first reconstructed image and the first detail part to produce a final filtered image.

Often it is desired to improve the quality of an original image by utilizing various digital processing techniques. While there exist many software programs that allow a person to perform a wide variety of processing on a digital image, these programs require intensive personal input and often a high level of training to be used effectively. Consequently, there has been a parallel development of techniques that can automatically analyze a digital image and, without any human involvement, improve the image quality.
One particular problem that is commonly encountered is the presence of noise in a digital image. This noise can arise for a variety of reasons and includes both systematic or regular noise and random noise. A number of techniques have been devised to automatically remove noise from a digital image. One common technique is to simply apply some sort of low pass or averaging filter to the image. While this technique and similar techniques are effective in reducing or eliminating noise, simple filtering techniques suffer from the disadvantage that simple filtering also tends to blur the image, reducing its visual quality.
One conventional method for reducing or eliminating noise while avoiding the problem of blurring the image utilizes a sigma filter. The sigma filter works by replacing the value of a pixel with the average of those neighboring pixels that are relatively close to its value. This distance is usually taken to be related to the variance of the image, and hence the noise level. The sigma filter has the advantage of preserving high frequency detail in the image while removing noise.
However, the sigma filter has the disadvantage that the filter kernel needs to be relatively large for the filter to be effective. The large filter requires more extensive computing resources and time, thereby making the sigma filter less desirable.
Therefore, it would be desirable to implement a filtering process that realizes the advantages of a sigma filter, which is reducing or eliminating noise while avoiding the problem of blurring the image, but is more economical in the computing requirements needed to implement it.

System and method for multi-scale sigma filtering using quadrature mirror filters