A radio-frequency tuning circuit includes an input tuning transformer, and an output tuning transformer. The input tuning transformer comprises a primary coil adapted to serve as input coil, and a secondary coil to which a pair of variable-capacitance diodes having cathodes thereof connected together are connected in parallel therewith to form a first tuning circuit. The output tuning transformer comprises a primary coil to which a variable-capacitance element is connected to form a second tuning circuit, and a secondary coil adapted to serve as output coil. The input and output tuning transformers are connected in such a manner as to form a double-tuning circuit. Q-factor of the output tuning transformer is made to be twice as high as that of the input tuning transformer, and resonant impedance of the first tuning circuit and that of the second tuning circuit are made to be substantially equal to each other.

1. Field of the Invention
The present invention relates to a radio-frequency tuning circuit adapted to be used for RF stage of a superheterodyne receiver, thereby suppressing generation of second harmonic signal.
2. Description of the Prior Art
In order to have a better understanding of the present invention, description will first be made with reference to FIGS. 5 and 6 of the accompanying drawings, which illustrate the circuit arrangement of conventional radio-frequency tuning circuit and frequency versus attenuation characteristics thereof respectively.
As will be seen, in the conventional radio-frequency tuning circuit shown in FIG. 5, an input tuning transformer T7 and output tuning transformer T8 are connected together in such a manner as to constitute a double-tuning circuit.
The input tuning transformer T7 comprises a primary coil L18, and a secondary coil L19. A capacitor C7, and a pair of variable-capacitance diodes comprising variable-capacitance diodes D10 and D11 having their cathodes connected together, are connected in parallel with the secondary coil L19 of the input tuning transformer T7. Thus, a tuning circuit 51 is formed by the secondary coil L19, variable-capacitance diodes D10, D11, and capacitor C7.
Further, the output transformer T8 comprises a primary coil L20, and secondary coil L21. A variable-capacitance diode D12 is connected to the primary coil L20 of the output tuning transformer T8, and a capacitor C8 is connected in parallel with the primary coil L20 of the output tuning transformer T8. Thus, a further tuning circuit 52 is formed by the primary coil L20, variable-capacitance diode D12, and capacitor C8.
The input tuning transformer T7 has the secondary coil L19 thereof tied to a tap of the primary coil L20 of the output tuning transformer T8 so that the tuning circuits 51 and 52 constitute the double-tuning circuit. R7 and R8 are bias resistors.
With the above conventional radio-frequency tuning circuit, signal derived from antenna circuit (not shown) is inputted to the input tuning transformer T7, and thus the signal as inputted is transferred from the primary coil L18 to the secondary coil L19 so that a signal of receiving frequency is selected at the tuning circuit 51. The signal as selected at the tuning circuit 51 is then transferred to the primary coil L20 of the output tuning transformer T8 so that signal of the receiving frequency is selected at the tuning circuit 52, the signal which in turn is transferred to and outputted from the secondary coil L21 of the output tuning transformer T8.
The input tuning transformer T7 and output tuning transformer T8 which constitute the conventional radio-frequency tuning circuit are ones exhibiting identical Q-factor. Further, the variable-capacitance diodes D10, D11, and D12 are ones having identical voltage versus capacitance characteristics. Still further, only the tuning circuit 51 uses a pair of variable-capacitance diodes, or the variable-capacitance diodes D10 and D11 having the cathodes thereof connected together, for the purpose of suppressing generation of the second harmonic signal which tends to be caused because of the voltage versus capacitance characteristics of the variable-capacitance diodes being non-linear.
The resonant impedance of the tuning circuit 51 is given by EQU Z.sub.7 =.omega.QT.sub.7 /TC.sub.7 ( 1)
where QT.sub.7 is the Q-factor of the input tuning transformer T.sub.7 ; TC.sub.7 is the combined capacitance of the tuning circuit 51; and .omega. represents 2.pi.f.
The resonant impedance of the tuning circuit 52 is given by EQU Z.sub.8 =.omega.QT.sub.8 /TC.sub.8 ( 2)
where QT.sub.8 is the Q-factor of the output tuning transformer T.sub.8 ; and TC.sub.8 is the combined capacitance of the tuning circuit 52; and .omega. represents 2.pi.f.
As mentioned above, the variable-capacitance diodes D.sub.10, D.sub.11 and D.sub.12 have identical voltage versus capacitance characteristics; and only the tuning circuit 51 uses a pair of variable-capacitance diodes (more specifically, two variable-capacitance diodes connected in series with each other); thus, the combined capacitance of the tuning circuit 52 is twice as high as that of the tuning circuit 51, and equation (2) can be rewritten as follows: EQU Z.sub.8 =.omega.QT.sub.8 /2TC.sub.7 ( 3).
Further, also as mentioned above, the input tuning transformer T.sub.7 and output tuning transformer T.sub.8 exhibit identical Q-factor; thus, the resonant impedance of the tuning circuit 52 and that of the tuning circuit 51 can be expressed as follows: EQU Z.sub.7 /Z.sub.8 =2 (4)
As will be seen, with the above conventional radio-frequency tuning circuit, despite the fact that the Q-factor of the input transformer T.sub.7 and that of the output tuning transformer T.sub.8 are equal to each other, the combined capacitance of the tuning circuit 52 is twice as high as that of the tuning circuit 51 so that the resonant impedance of tuning circuit 52 turns out to be twice as high as that of the tuning circuit 51. Thus, such difference in resonant impedance between the tuning circuits 51 and 52 results in the Q-factors of these tuning circuits being different from each other.
Thus, the radio-frequency tuning circuit including the double-tuning circuit constituted by the tuning circuits 51 and 52 turns out to be a circuit which is poor in terms of Q-factor balance. Another disadvantage of the above conventional radio-frequency tuning circuit is such that because of the fact that the bandwidth thereof, is broadened as shown at 63 in FIG. 6 for the purpose of eliminating sensitivity difference which tends to be caused due to tracking error, the circuit is susceptible to occurrence of ripple as shown by the solid characteristic curve 61 in FIG. 6.
When ripple occurs in the characteristics of the radio-frequency tuning circuit as mentioned above, frequency F1 at which attenuation is minimized is lower than the center frequency F0 of such characteristics with no ripple as shown by the dotted curve 62. This means that the above conventional radio-frequency tuning circuit has such a drawback that when the frequency F1 for minimum attenuation is deviated from the receiving frequency due to variation in temperature and/or humidity, the signal of the receiving frequency tends to be attenuated so that the sensitivity is deteriorated.
Furthermore, with the radio-frequency tuning circuit having such characteristics, when it is tuned to receive a signal of 1010 KHz for example, there is a tendency that the frequency F1 for minimum attenuation is brought into registration with 1010 KHz; thus the bandwidth 63 becomes broader at a portion higher than the frequency F1, so that assuming that signals of 1030 KHz and 1050 KHz, both of which fall within the bandwidth, are inputted, these signals are transferred without being attenuated. That is, despite the attempt to suppress second harmonic interference at the tuning circuit 51, the signal of 1030 KHz is permitted to reach the tuning circuit 52, so that the second harmonic of the 1030 KHz signal, i.e., a signal of 2060 KHz is generated at the tuning circuit 52. This gives rise to a problem that there is caused such intermodulation that the second harmonic signal of 2060 KHz and the signal of 1050 KHz are combined, so that a signal of 1010 KHz is generated.

Electronic-tuning type radio-frequency tuning circuit


A recorder, method, device, and interpretation apparatus for executing code commands. The invention is a device which functions in response to code commands comprising: means to execute a function in response to a code command having a format for the device; and means to execute the function in response to a code command having a format for a different device. The invention is also a recorder comprising means to execute a first type of recorder function corresponding to a second type of recorder commands. In another aspect, the invention is a method of controlling a recorder comprising: receiving a second type of recorder command; mapping the second type of recorder command into a corresponding first type of recorder function; and executing the corresponding first type of recorder function. In yet another aspect, the invention is an interpretation apparatus for receiving a second type of recorder command and outputting a corresponding first type of recorder.

Devices which function in response to code commands are very well known, for example televisions, VCRs, CD players, DVD recorders, personal video recorders, cable boxes, to name but a few types. In most types of devices, the code commands are organized so as to have a prefix which indicates the type of device being controlled, i.e., VCR or DVD or STB, for example. Systems that receive broadcast signals and generate a display signal for a television set are known as set-top boxes ("STB"), whether they are actually on top of a television set or any other location outside or within the television set itself. Set-top boxes are currently available for receiving digital satellite television broadcast, cable television broadcast, community antenna service, dial up, cable, or DSL Internet service, or combinations thereof.
An STB is any electronic device designed to produce output on a conventional television set, having one or more inputs connected to a communications channel such as telephone, ISDN, optical fiber, or cable. STB's usually allow the user to interact with the programs shown on the television in some way. Many STB's offer on-screen program guides, known as electronic program guides ("EPG"), that allow the user to perform many program related functions, such as program searching, parental controls, and program recording. Control of external devices such as VCR's, DVD players, personal video recorders and television sets, for example, is also possible. Typically, a user interacts with the STB via an infrared ("IR") remote control or manually entering commands via buttons on the STB.
Many STB's having EPG's allow a user to select a show from the STB's EPG and record it to a VCR by sending a one-touch record command to the STB. In response to receiving the one-touch record command, the STB sends a VCR IR code record signal via an IR blaster to the VCR. The VCR IR code signal is received and executed by the VCR. At the end of the program, the STB usually sends a stop recording VCR IR code command to the VCR via the IR blaster. The VCR then responds accordingly.
When an owner of such an STB decides to upgrade from an analog VCR to a digital recorder, such as a personal video recorder ("PVR") or a digital versatile disc player ("DVD") player, such an STB is not capable of communicating with the digital recorder. If available, an upgraded owner must use a satellite and cable guide that is built into the digital recorder to perform program recordings. Some digital recorders may not offer a guide with satellite or other EPG information. The user will not be able to use the EPG of the STB to send record commands to the digital recorder because the digital recorder answers only to IR codes with a digital recorder identity. The identity of a code command is delineated by that code's prefix/preamble. STB's that were designed at a time when digital recorders were not available will not be able to communicate with the digital recorder because they can only produce code commands with a VCR identity/preamble.
Thus, a need exists for a personal video recorder that can understand various IR codes types, such as VCR IR codes and digital recorder IR codes. A need also exists for an apparatus that can receive a first type of IR code from an STB, convert the first type of IR code to a second type of IR code, and send the second type of IR code to a recording device that can execute the second type of IR code.

Video processing apparatus which can respond to non-native remote commands and method of operation thereof


The semiconductor integrated circuit device of the present invention includes a plurality of integrated circuits. The scheduling circuit selects an arbitrary number of integrated circuit from the plurality of integrated circuits, and connects the selected integrated circuits between the power line and the ground line such that the selected integrated circuits are arranged in series or in series-parallel. The scheduling circuit sets a combination of connection of the selected integrated circuits such that the consumption power of the total of the selected integrated circuits becomes minimum. The voltage control circuit sets a potential of a serial connecting portion of the selected integrated circuits. The data control circuit has an input output circuit for inputting and outputting data between the selected integrated circuits, and the outside, and a level conversion circuit for converting a level of data between certain integrated circuits.

1. Field of the Invention
The present invention relates to a semiconductor integrated circuit device to which a plurality of integrated circuits such as, microprocessors, logic circuits and the like are connected in series.
2. Description of the Related Art
Recently, the degree of integration of an integrated circuit device has been significantly improved, and in a semiconductor memory of a giga (G) bit order, several hundred million elements are integrated in one chip. In a 64-bit microprocessor, several million to ten million elements are integrated in one chip. The improvement of the degree of the integration is achieved by downsizing the elements. In the case of a 1 G-bit DRAM (dynamic random access memory), MOS (metal oxide semiconductor) transistors having a gate length of 0.15 .mu.m are used, and for a higher degree of integration, MOS transistors having a gate length of 0.1 .mu.m or less are used.
In a MOS transistor of such a small size, deterioration of transistor characteristics occurs because of the generation of a hot carrier, or breakdown of insulation films occurs because of the TDDB (time dependent dielectric breakdown). Further, in the case where the concentration of impurities in a bulk or a channel portion is raised in order to suppress a decrease in threshold voltage caused by shortening of the channel length, the junction breakdown voltage between a source and a drain, is decreased.
In order to maintain the reliability of these fine elements, it is effective to decrease the supply voltage. More specifically, the generation of a hot carrier is avoided by weakening the electric field running in the lateral direction between the source and drain, and the TDDB is prevented by weakening the electric field running in the vertical direction between the gate and bulk. Further, by decreasing the supply voltage, a reverse bias acting on the junction between the source and the bulk or between the drain and the bulk, is decreased, thus making it possible to follow up a decrease in the junction breakdown voltage.
In the meantime, in a bipolar transistor, a high-speed operation can be achieved by shortening the base width; however if the base width is excessively shortened, the bipolar transistor cannot function as a transistor because of punch through. In order to avoid this, it is necessary to increase the concentration of impurities in the base. Further, if the current density is increased, the cutoff frequency is decreased. In order to avoid this so-called Kirk effect (or base pushout effect), it is necessary to increase the concentration of impurities in the collector.
In the downsized bipolar transistor, the concentration of the impurities in the base and the collector region must be increased, and with an increase in the concentration, the base-collector junction breakdown voltage is decreased. In order to avoid this, a decrease in the supply voltage is effective as in the case of the MOS transistor.
As described above, in the case where elements are downsized, it is necessary to decrease the supply voltage in order to maintain the reliability of the device; however, at the same time, the structure of the device is complicated for a user who actually deals with the semiconductor integrated circuit device (semiconductor chip), creating a problem. In other words, for a user, it is not preferable that the supply voltage should differ from one chip to another among a plurality of semiconductor chips. Further, it is not preferable that the supply voltage which has been used in the conventional structure should become unusable as it is.
Recently, a device as shown in FIG. 1, in which the supply voltage is decreased within a semiconductor chip, has been proposed. In this device, a voltage down converter 111 and an integrated circuit 110 are connected in series between a power line (supply voltage Vcc) and a ground line (ground voltage Vss), thus maintaining the voltage applied to the integrated circuit 110 at Vcc' which is lower than Vcc. With use of the voltage down converter 111, the reliability of the semiconductor chip is increased.
However, in a device of the above-described type, the power consumed in the voltage down converter 111 is wastefully used. Therefore, it is difficult to achieve a power-saving performance of the semiconductor chip as a whole, creating a new problem. For example, in the case where supply voltage Vcc=3 V and the voltage applied to the integrated circuit 110 is 1.5 V, a subtracted voltage difference of 1.5 V is applied to the voltage down converter 111, and thus a half of the total consumption power is used in the voltage down converter 111.
More specifically, the consumption power P of a semiconductor chip as a whole is expressed by P=CV.sup.2 f, where V indicates the difference between the supply voltage and the ground voltage, C indicates the capacitance between the power sources of the semiconductor chip, and f indicates the operation frequency. In FIG. 1, if the capacitance between the power sources of the voltage down converter 111 and the capacitance between the power sources of the integrated circuit 110 are both equal to C1, an equation, Vcc'=Vcc/2, is established. Therefore, the power consumed in the semiconductor chip as a whole is (C1)V.sup.2 f and the power consumed in the voltage down converter 111 is (C1/2)V.sup.2 f. Thus, one half of the consumption power of the semiconductor chip as a whole is consumed by the voltage down converter 111.
For the purpose of suppressing the consumption of the power in a voltage down converter, the following device has been proposed (Jap. Pat. Appln. KOKAI Publication No. H4-3153131). According to this technique, two integrated circuits are connected in series between the power line and the ground line, and the current flowing through the first integrated circuit is recycled in the second integrated circuit. Further, a voltage control circuit is connected to a power line within the semiconductor chip, which is a connection portion between the first and second integrated circuits, so as to maintain a voltage of the power line in the chip at constant.
In this device, however, if the first and second integrated circuits do not function at the same time, the load on the voltage control circuit is increased. Therefore, a voltage control circuit having a drive capability as large as that of the voltage down converter is required. As a result, the consumption power cannot be decreased.
As described above, conventionally, in a semiconductor integrated circuit device employing fine elements, a voltage down converter is used in order to maintain the reliability of the device and to avoid the complexity of the structure; however, the power consumed in such a voltage down converter is wasted.
Meanwhile, in a device in which a plurality of integrated circuits are connected in series without using a voltage down converter, the drive capability of the internal voltage control circuit must be enhanced when these integrated circuits are not operated at the same time. As a result, the power substantially the same as that consumed in a voltage down converter when the voltage down converter is used, is consumed by the voltage control circuit, and such power is wastefully used.

Integrated circuit with stacked sub-circuits between Vcc and ground so as to conserve power and reduce the voltage across any one transistor


Animal attractant compositions, devices, systems and methods that can be deployed to attract game animals, such as deer by stimulating several of the animal's senses to attract animals to a desired location. The invention can use a combination of ultraviolet brighteners for visual interest and one or more of deer urine based scents, foods, mineral or salt. The invention capitalizes on the link between many animals' ability to see ultraviolet light with their desire to visualize urine territory markers left by other animals of the same species.

In the past, science has discovered that some animals possess vision capable of detecting light both in the visible spectrum (˜400 to ˜700 nanometers wavelength) and the near ultraviolet (˜200 to ˜400 nanometers wavelength). The evolutionary advantages afforded by this ability are varied. Many fruits, flowers, and seeds are more prominent when viewed in ultraviolet light as compared with normal visible wavelengths. Insects use ultraviolet emissions from stars and the moon to aid in flight navigation. The blood and urine of some animals is easily detected using ultraviolet light.
Various fabric dyes have been found to "glow" when viewed with ultraviolet light and are undesirable in hunting applications. Clothing treated with such dyes, including clothing that appears camouflaged when viewed in visible light, has been found to be unsuitable for hunters. Hunters wearing such clothing appears as a bright, moving beacon to game animals. Calling attention to oneself in such a manner often frightens game animals causing them to flee from the hunter.
Common household laundry detergents have often included ultraviolet brighteners designed to give clothes a whiter appearance upon washing. While a whiter appearance can be considered a positive selling point for the average consumer, for the hunter seeking to blend into the forest, using such products only compounds the problem of camouflage. An entire industry has developed to produce fabric dyes and detergents that are themselves not visible in ultraviolet light or mute ultraviolet signatures in existing products.
While all the aforementioned prior art seeks to avoid detection by animals capable of seeing ultraviolet light, there is little in the prior art directed towards using an animal's ability to see ultraviolet light as an attractant.
Published Patent Application 2007/0199228 to Johnson (formerly U.S. patent application Ser. No. 11/711,409) describes a decoy with a surface reflection that closely matches the spectral reflectance of the animal it is designed to mimic, including both human-visible and ultraviolet wavelengths in order to make the decoy appear more realistic to the target animals.
However, this reference is limited in scope insofar as it only teaches the use of ultraviolet reflectance for lifelike mimicry. The prior art publication is silent about the use of ultraviolet reflectance in combination with other attractant methods or the use of ultraviolet brighteners to render an object "super bright" as an animal attractant.
Thus, the need exists for solutions to the above problems with the prior art.

This patent is subject to a terminal disclaimer.


A system and method are disclosed for merging manual parameters with predefined parameters. The system includes a parse module configured to receive a command string having multiple nested manual parameters and a build module configured to generate a parameter tree having manual parameter nodes and predefined parameter nodes. The system may also include a search module configured to compare manual parameter nodes to predefined parameter nodes to identify matching parameter contexts, and a command module configured to generate a command string. The method includes receiving a command string having multiple nested manual parameters, identifying manual parameters within the command string, and generating a parameter tree having manual parameter nodes and predefined parameter nodes. The method also includes comparing manual parameter nodes to predefined parameter nodes to identify parameter nodes having a matching parameter context, and generating a command string.

1. Field of the Invention
This invention relates to computer application programs, and more particularly the present invention relates to merging manual parameters with predefined parameters to form a command string.
2. Description of the Related Art
An Information Management System (IMS) is a hierarchical database management system that has wide spread usage in many large enterprises where high transaction volume, reliability, availability and scalability are of the utmost importance. While IMS provides the software and interfaces for running the businesses of many of the world's large corporations, a company typically tailors specific application programs in order to have IMS perform proprietary or custom work for the enterprise. IMS application programs are typically coded in COBOL, PL/I, C, PASCAL or assembly language.
Also available for IMS is a system management application having an Interactive System Productivity Facility (ISPF) panel interface with the ability to manage a group of IMSs from a Time Sharing Options (TSO) Single Point of Control (SPOC). With a SPOC interface, commands may be submitted to an operations manager. The operations manager controls the operations of the group of IMSs (hereinafter "IMSplex") and also provides an application programming interface (API) through which commands can be issued and responses received. The SPOC interfaces include the TSO SPOC, the Restructured Extended Executor SPOC API, and the IMS Control Center. Users may also write additional applications to submit commands. By using one of the SPOC interfaces, for example the TSO SPOC, the user is able to write single points of control that communicate with the operations manager.
This IMS TSO SPOC is a software program that is configured to manage all IMS systems within the IMSplex. With the SPOC, commands may be issued to all members of an IMSplex at the same time. There can be more than one type of SPOC in an IMSplex, and there can be any number of SPOCs active. TSO SPOC communicates with one operations manager (OM) address space. The OM then communicates with all IMS address spaces in the IMSplex through a Structured Call Interface (SCI).
The IMS TSO SPOC provides several functions to an IMSplex. First, the IMS TSO SPOC presents a single system image for an IMSplex by allowing the user to issue commands to all IMSs in the IMSplex from a single console. Additionally SPOC displays consolidated command responses from multiple IMS address spaces. SPOC may also be configured to send a message to an IMS terminal connected to any IMS control region in the IMSplex.
Generally, commands in the IMS TSO SPOC application are manually entered on a command line prompt. A user may define command shortcuts and thereby reduce the length of commands. A combination of manually entered commands and predefined parameter commands may be utilized in issuing a complete command.
The IMS operator command syntax supports various parameters and the commands can be quite long. To help the operator, the IMS TSO SPOC allows the user to predefine certain parameters using a shortcut. When the user issues a short command string the TSO SPOC will combine both the necessary elements of the short manually typed string and the necessary elements of the user's predefined or redefined default parameters to compose a complete command.
The TSO SPOC does not simply append the predefined parameters to the entered command, but makes possible a merging of typed manual parameters with the predefined parameters. The shortcut may include typed manual parameters that are to override predefined parameters in the shortcut. This allows the user to change values of existing predefined parameters or add new parameters to the command, without reprogramming the shortcuts.
However, current TSO SPOC implementations do not account for multiple levels of nested parameters. Typically, the nested levels are indicated by delimiters such as a pair of parenthesis. Descendent levels of nesting are indicated by a parenthesis pair within an external parenthesis pair. For example, a command may include manual parameters within a parenthesis set which are also within a pair of parenthesis.
Current TSO SPOC implementations are unable to properly identify parameters at different nesting levels because the parameters often have the same name or token that identifies the parameter. However, parameter nesting results in parameters of the same name having a different context or meaning. Current TSO SPOC implementations are unable to identify this context distinction. So, the user is unable to use nested parenthesis in the command string with current IMS. The user is also unable to change values of existing predefined parameters or add new parameters to the command string when the parameters are found at a different level. This limitation of current TSO SPOC implementations severely restricts the value and benefit of the shortcut feature in the TSO SPOC implementations.
From the foregoing discussion, it should be apparent that a need exists for a system and method that will parse TSO SPOC command strings and merge parameters regardless of the amount of parameter nesting involved. Beneficially, such a system and method would eliminate the problem that exists with multiple levels of parameters and nested parenthesis.

System and method for merging manual parameters with predefined parameters

International Business Machines Corporation


The present invention relates to a zirconium, rare earth containing composition comprising zirconium, cerium, neodymium and praseodymium components and the use of this composition in a catalyst composition useful for the treatment of gases to reduce contaminants contained therein and method process to make the catalyst composition. The catalyst has the capability of substantially simultaneously catalyzing the oxidation of hydrocarbons and carbon monoxide and the reduction of nitrogen oxides.

1. Field of the Invention
The present invention relates to a zirconium, rare earth containing composition comprising zirconium, cerium, neodymium and praseodymium components and the use of this composition in a catalyst composition useful for the treatment of gases to reduce contaminants contained therein and method process to make the catalyst composition. The present invention relates to an improved catalysts of the type generally referred to as "three-way conversion" or "TWC" catalysts. TWC catalysts have the capability of substantially simultaneously catalyzing the oxidation of hydrocarbons and carbon monoxide and the reduction of nitrogen oxides.
2. Discussion of Related Art
Three-way conversion catalysts (TWC) have utility in a number of fields including the treatment of exhaust from internal combustion engines, such as automobile and other gasoline-fueled engines. Emissions standards for unburned hydrocarbons, carbon monoxide and nitrogen oxides contaminants have been set by various governments and must be met, for example, by new automobiles. In order to meet such standards, catalytic converters containing a TWC catalyst are located in the exhaust gas line of internal combustion engines. The catalysts promote the oxidation by oxygen in the exhaust gas of the unburned hydrocarbons and carbon monoxide and the reduction of nitrogen oxides to nitrogen.
Known TWC catalysts which exhibit good activity and long life comprise one or more platinum group metals (e.g., platinum or palladium, rhodium, ruthenium and iridium) located upon a high surface area, refractory oxide support, e.g., a high surface area alumina coating. The support is carried on a suitable carrier or substrate such as a monolithic carrier comprising a refractory ceramic or metal honeycomb structure, or refractory particles such as spheres or short, extruded segments of a suitable refractory material.
U.S. Pat. No. 4,134,860 relates to the manufacture of catalyst structures. The catalyst composition can contain platinum group metals, base metals, rare earth metals and refractory, such as alumina support. The composition can be deposited on a relatively inert carrier such as a honeycomb.
High surface area alumina support materials, also referred to as "gamma alumina" or "activated alumina", typically exhibit a BET surface area in excess of 60 square meters per gram ("m.sup.2 /g"), often up to about 200 m.sup.2 /g or more. Such activated alumina is usually a mixture of the gamma and delta phases of alumina, but may also contain substantial amounts of eta, kappa and theta alumina phases. It is known to utilize refractory metal oxides other than activated alumina as a support for at least some of the catalytic components in a given catalyst. For example, bulk ceria, zirconia, alpha alumina and other materials are known for such use. Although many of these materials suffer from the disadvantage of having a considerably lower BET surface area than activated alumina, that disadvantage tends to be offset by a greater durability of the resulting catalyst.
In a moving vehicle, exhaust gas temperatures can reach 1000.degree. C. or higher, and such elevated temperatures cause the activated alumina (or other) support material to undergo thermal degradation caused by a phase transition with accompanying volume shrinkage, especially in the presence of steam, whereby the catalytic metal becomes occluded in the shrunken support medium with a loss of exposed catalyst surface area and a corresponding decrease in catalytic activity. It is a known expedient in the art to stabilize alumina supports against such thermal degradation by the use of materials such as zirconia, titania, alkaline earth metal oxides such as baria, calcia or strontia or rare earth metal oxides, such as ceria, lanthana and mixtures of two or more rare earth metal oxides. For example, see C. D. Keith et al U.S. Pat. No. 4,171,288.
Bulk cerium oxide (ceria) is disclosed to provide an excellent refractory oxide support for platinum group metals other than rhodium, and enables the attainment of highly dispersed, small crystallites of platinum on the ceria particles, and that the bulk ceria may be stabilized by impregnation with a solution of an aluminum compound, followed by calcination. U.S. Pat. No. 4,714,694 of C. Z. Wan et al, discloses aluminum-stabilized bulk ceria, optionally combined with an activated alumina, to serve as a refractory oxide support for platinum group metal components impregnated thereon. The use of bulk ceria as a catalyst support for platinum group metal catalysts other than rhodium, is also disclosed in U.S. Pat. No. 4,727,052 of C. Z. Wan et al and in U.S. Pat. No. 4,708,946 of Ohata et al.
U.S. Pat. No. 4,808,564 discloses a catalyst for the purification of exhaust gases having improved durability which comprises a support substrate, a catalyst carrier layer formed on the support substrate and catalyst ingredients carried on the catalyst carrier layer. The catalyst carrier layer comprises oxides of lanthanum and cerium in which the molar fraction of lanthanum atoms to total rare earth atoms is 0.05 to 0.20 and the ratio of the number of the total rare earth atoms to the number of aluminum atoms is 0.05 to 0.25.
U.S. Pat. No. 4,438,219 discloses an alumina supported catalyst for use on a substrate. The catalyst is stable at high temperatures. The stabilizing material is disclosed to be one of several compounds including those derived from barium, silicon, rare earth metals, alkali and alkaline earth metals, boron, thorium, hafnium and zirconium. Of the stabilizing materials barium oxide, silicon dioxide and rare earth oxides which include lanthanum, cerium, praseodymium, neodymium, and others are indicated to be preferred. It is disclosed that contacting them with a calcined alumina film permits the calcined alumina film to retain a high surface area at higher temperatures.
European Patent Application 95/01849 (Publication No. 95/35152) discloses a layered catalyst composite including an oxygen storage composition which comprises a diluent such as zirconia, ceria, and one or more rare earth oxides selected from lanthana, neodymia and yttria. Also disclosed as oxygen storage components are praseodymia, ceria and neodymia which can be applied as soluble salts to a catalyst composition.
U.S. Pat. Nos. 4,476,246, 4,591,578 and 4,591,580 disclose three-way catalyst compositions comprising alumina, ceria, an alkali metal oxide promoter and noble metals. U.S. Pat. Nos. 3,993,572 and 4,157,316 represent attempts to improve the catalyst efficiency of Pt/Rh based TWC systems by incorporating a variety of metal oxides, e.g., rare earth metal oxides such as ceria and base metal oxides such as nickel oxides. U.S. Pat. No. 4,591,518 discloses a catalyst comprising an alumina support with components deposited thereon consisting essentially of a lanthana component, ceria, an alkali metal oxide and a platinum group metal. U.S. Pat. No. 4,591,580 discloses an alumina supported platinum group metal catalyst. The support is sequentially modified to include support stabilization by lanthana or lanthana rich rare earth oxides, double promotion by ceria and alkali metal oxides and optionally nickel oxide. Palladium containing catalyst compositions e.g. U.S. Pat. No. 4,624,940 have been found useful for high temperature applications. The combination of lanthanum and barium is found to provide a superior hydrothermal stabilization of alumina which supports the catalytic component, palladium.
U.S. Pat. No. 4,294,726 discloses a TWC catalyst composition containing platinum and rhodium obtained by impregnating a gamma alumina carrier material with an aqueous solution of cerium, zirconium and iron salts or mixing the alumina with oxides of, respectively, cerium, zirconium and iron, and then calcining the material at 500 to 700.degree. C. in air after which the material is impregnated with an aqueous solution of a salt of platinum and a salt of rhodium dried and subsequently treated in a hydrogen-containing gas at a temperature of 250-650.degree. C. The alumina may be thermally stabilized with calcium, strontium, magnesium or barium compounds. The ceria-zirconia-iron oxide treatment is followed by impregnating the treated carrier material with aqueous salts of platinum and rhodium and then calcining the impregnated material.
U.S. Pat. No. 4,780,447 discloses a catalyst which is capable of controlling HC, CO and NO.sub.x as well as H.sub.2 S in emissions from the tailpipe of catalytic converter equipped automobiles. The use of the oxides of nickel and/or iron is disclosed as an H.sub.2 S gettering compound.
U.S. Pat. No. 4,965,243 discloses a method to improve thermal stability of a TWC catalyst containing precious metals by incorporating a barium compound and a zirconium compound together with ceria and alumina. This is disclosed to form a catalytic moiety to enhance stability of the alumina washcoat upon exposure to high temperature.
J01210032 (and AU-615721) discloses a catalytic composition comprising palladium, rhodium, active alumina, a cerium compound, a strontium compound and a zirconium compound. These patents suggest the utility of alkaline earth metals in combination with ceria, and zirconia to form a thermally stable alumina supported palladium containing washcoat.
U.S. Pat. Nos. 4,624,940 and 5,057,483 refer to ceria-zirconia containing particles. It is found that ceria can be dispersed homogeneously throughout the zirconia matrix up to 30 weight percent of the total weight of the ceria-zirconia composite to form a solid solution. A co-formed (e.g. co-precipitated) ceria-zirconia particulate composite can enhance the ceria utility in particles containing ceria-zirconia mixture. The ceria provides the zirconia stabilization and also acts as an oxygen storage component. The '483 patent discloses that neodymium and/or yttrium can be added to the ceria-zirconia composite to modify the resultant oxide properties as desired.
U.S. Pat. No. 4,504,598 discloses a process for producing a high temperature resistant TWC catalyst. The process includes forming an aqueous slurry of particles of gamma or other activated alumina and impregnating the alumina with soluble salts of selected metals including cerium, zirconium, at least one of iron and nickel and at least one of platinum, palladium and rhodium and, optionally, at least one of neodymium, lanthanum, and praseodymium. The impregnated alumina is calcined at 600.degree. C. and then dispersed in water to prepare a slurry which is coated on a honeycomb carrier and dried to obtain a finished catalyst.
U.S. Pat. Nos. 3,787,560, 3,676,370, 3,552,913, 3,545,917, 3,524,721 and 3,899,444 all disclose the use of neodymium oxide for use in reducing nitric oxide in exhaust gases of internal combustion engines. U.S. Pat. No. 3,899,444 in particular discloses that rare earth metals of the lanthanide series are useful with alumina to form an activated stabilized catalyst support when calcined at elevated temperatures. Such rare earth metals are disclosed to include lanthanum, cerium, praseodymium, neodymium and others.
TWC catalyst systems comprising a carrier and two or more layers of refractory oxide are disclosed. One of the purposes of using catalysts having two or more layers is to isolate constituents of compositions in different layers to prevent interaction of the catalysts. Disclosures regarding catalysts comprising two or more layers are included in U.S. Ser. No. 08/645,985 and in European Patent Application Nos. 95/00235 and 95/01849, Japanese Patent Publication Nos. 105240/1982, 52530/1984, 19036/1985, 31828/1985 and 232253/1985.
Japanese Patent Publication No. 145381/1975 discloses a catalyst-supported structure for purifying exhaust gases comprising a thermally insulating ceramic carrier and at least two layers of catalyst containing alumina or zirconia, the catalysts in the catalyst containing alumina or zirconia layers being different from each other.
Japanese Patent Publication No. 127649/1984 discloses a catalyst for purifying exhaust gases, comprising an inorganic carrier substrate such as cordierite, an alumina layer formed on the surface of the substrate and having deposited thereon at least one rare earth metal such as lanthanum and cerium and at least one of platinum and palladium, and a second layer formed on the aforesaid first alumina-based layer and having deposited thereon a base metal such as iron or nickel, and at least one rare earth metal such as lanthanum, and rhodium.
Japanese Kokai 71538/87 discloses a catalyst layer supported on a catalyst carrier and containing one catalyst component selected from the group consisting of platinum, palladium and rhodium. An alumina coat layer is provided on the catalyst layer. The coat layer contains one oxide selected from the group consisting of cerium oxide, nickel oxide, molybdenum oxide, iron oxide and at least one oxide of lanthanum and neodymium (1-10% by wt.).
U.S. Pat. Nos. 3,956,188 and 4,021,185 disclose a catalyst composition having (a) a catalytically active, calcined composite of alumina, a rare earth metal oxide and a metal oxide selected from the group consisting of an oxide of chromium, tungsten, a group IVB metal and mixtures thereof and (b) a catalytically effective amount of a platinum group metal added thereto after calcination of said composite. The rare earth metals include cerium, lanthanum and neodymium.
U.S. Pat. No. 4,806,519, discloses a two layer catalyst structure having alumina, ceria and platinum on the inner layer and aluminum, zirconium and rhodium on the outer layer.
JP-88-240947 discloses a catalyst composite which includes an alumina layer containing ceria, ceria-doped alumina and at least one component selected from the group of platinum, palladium and rhodium. There is a second layer containing lanthanum-doped alumina, praseodymium-stabilized zirconium, and lanthanum oxide and at least one component selected from the group of palladium and rhodium. The two layers are placed on a catalyst carrier separately to form a catalyst for exhaust gas purification.
Japanese Patent J-63-205141-A discloses a layered automotive catalyst in which the bottom layer comprises platinum or platinum and rhodium dispersed on an alumina support containing rare earth oxides, and a top coat which comprises palladium and rhodium dispersed on a support comprising alumina, zirconia and rare earth oxides.
Japanese Patent J-63-077544-A discloses a layered automotive catalyst having a first layer comprising palladium dispersed on a support comprising alumina, lanthana and other rare earth oxides and a second coat comprising rhodium dispersed on a support comprising alumina, zirconia, lanthana and rare earth oxides.
Japanese Patent J-63-007895-A discloses an exhaust gas catalyst comprising two catalytic components, one comprising platinum dispersed on a refractory inorganic oxide support and a second comprising palladium and rhodium dispersed on a refractory inorganic oxide support.
U.S. Pat. No. 4,587,231 discloses a method of producing a monolithic three-way catalyst for the purification of exhaust gases. First, a mixed oxide coating is provided to a monolithic carrier by treating the carrier with a coating slip in which an active alumina powder containing cerium oxide is dispersed together with a ceria powder and then baking the treated carrier. Next platinum, rhodium and/or palladium are deposited on the oxide coating by a thermal decomposition. Optionally, a zirconia powder may be added to the coating slip.
U.S. Pat. No. 4,923,842 discloses a catalytic composition for treating exhaust gases comprising a first support having dispersed thereon at least one oxygen storage component and at least one noble metal component, and having dispersed immediately thereon an overlayer comprising lanthanum oxide and optionally a second support. The layer of catalyst is separate from the lanthanum oxide. The noble metal can include platinum, palladium, rhodium, ruthenium and iridium. The oxygen storage component can include the oxide of a metal from the group consisting of iron, nickel, cobalt and the rare earths. Illustrative of these are cerium, lanthanum, neodymium and praseodymium.
U.S. Pat. No. 5,057,483, referred to above, discloses a catalyst composition suitable for three-way conversion of internal combustion engine, e.g., automobile gasoline engine, exhaust gases and includes a catalytic material disposed in two discrete coats on a carrier. The first coat includes a stabilized alumina support on which a first platinum catalytic component is dispersed. The first coat also includes bulk ceria, and may also include bulk iron oxide, a metal oxide (such as bulk nickel oxide) which is effective for the suppression of hydrogen sulfide emissions, and one or both of baria and zirconia dispersed throughout as a thermal stabilizer. The second coat, which may comprise a top coat overlying the first coat, contains a co-formed (e.g., co-precipitated) rare earth oxide-zirconia support on which a first rhodium catalytic component is dispersed, and a second activated alumina support having a second platinum catalytic component dispersed thereon. The second coat may also include a second rhodium catalytic component, and optionally, a third platinum catalytic component, dispersed as an activated alumina support.
It is a continuing goal to develop a three-way catalyst system which is inexpensive and stable. At the same time the system should have the ability to oxidize hydrocarbons and carbon monoxide while reducing nitrogen oxides to nitrogen.

Catalyst composition containing oxygen storage components


A fluid for use in hydraulic fracturing contains underivatized guar or a guar gum derivative as viscosifying or gelling polymer, a crosslinking agent, carbon dioxide as foaming agent and urea and, optionally, a bifunctional organic compound containing at least one hydroxyl group and at least one quaternary group and, optionally, a non-gaseous foaming agent. The fluid may be characterized by a low pH such as a pH than or equal to 3.0 and less than or equal to 5.0.

Hydraulic fracturing is the process of enhancing oil and/or gas production from producing wells or enhancing the injection of water or other fluids into injection wells. Typically, a fracturing fluid is injected into the well, passing down the tubulars to the subterranean formation penetrated by the wellbore.
The fluid is then pumped at rates and pressures that exceed the confining stresses in the formation. This creates or enlarges cracks or fissures in the formation which extend away from the wellbore. As more fluid is injected, the fracture may continue to expand. The fracturing fluid may contain propping agents which are carried to the fracture and placed in the growing crack; the viscosity of such fluids being sufficient to adequately carry and place proppant into the formation.
Often, the fracturing fluid is composed of at least one water-soluble polymer which has been hydrated in water and which has been chemically modified with a crosslinking agent in order to increase fluid viscosity. Typical water-soluble polymers for use in fracturing fluids are those based on guar gum and include guar derivatives. Typical crosslinking agents are typically metallic and include organometallics. Such viscosified fluids form three-dimensional gels.
Certain subterranean formations subjected to hydraulic fracturing are water sensitive. For instance, formations rich in swellable and migrating clays are water sensitive due to the presence of kaolinite, chlorite, illite and mixed layers of illite and smectite. Imbibed water increases the potential for damage to the formation.
Formation damage further results when aqueous based fracturing fluids are used due to adverse water saturation effects (including sub-irreducible water saturation). Saturation of the formation with water typically reduces permeability to hydrocarbons. This, in turn, can reduce productivity of the well.
Water retention issues may be especially acute in tight gas formations which are water-wet and under-saturated where the initial water saturation in the reservoir is less than the capillary equilibrium irreducible water saturation. When exposed to aqueous based fluids, these formations trap water for long periods of time, if not permanently, especially in near-wellbore regions. As such, in certain formations, such as shale, flow back of 25 to 40 weight percent of fracturing water must be addressed prior to putting produced gas in the pipeline.
Fluids are typically energized with gases, such as nitrogen and carbon dioxide, to minimize the amount of liquids introduced into the formation and to enhance recovery of fluids from the well. In some cases, a mixture of such gases may be used. A mixture of two of such gases is referred to as a binary fluid. Typically, fluids are considered energized if the volume percent of the energizing medium to the total volume of the treatment fluid (defined as "quality") is less than 53%; they are considered as foams if the volume percent is greater than 53%. By minimizing the amount of water in the fracturing fluid, energized or foamed fluids minimize concerns of flowback water as well as the adverse effects caused by water retention. Further, energized and foamed fluids are useful at wellsites were water availability is limited.
Energized and foamed fracturing fluids are known, however, to be unstable in high temperature wells, such as wells having a formation temperature greater than 225° F. as evidenced by premature breakage of the crosslinked polymer. Such breakage decreases the viscosity and thus the stability of the fluid. For instance, in carbon dioxide energized and foamed fracturing fluids, carbonic acid forms when carbon dioxide is dissolved in water. Carbonic acid is known to degrade the crosslinked polymer.
It is desired therefore to develop a method of fracturing a formation using an energized or foamed fracturing fluid which is stable in wells having a formation temperature in excess of 225° F.

Methods of using energized well treating fluids


Briefly stated, a compact disk/diskette case is provided. The case includes a central section which removably receives a plurality of CD drawers, a top section which defines at least one bay sized to received a standard 3.5" diskette, and a bottom section which slidably receives a storage drawer. The case includes adhesive feet on its bottom surface to enable the case to be mounted to a computer monitor.. Each the CD drawer includes a tray and a door. The tray has a hollow boss which is sized to enable a CD to be slidably journaled about the boss. The door is pivotally connected to the tray and has a projection which is received in the hollow portion of the tray boss. The door projection and the tray boss engage each other to removably hold a CD in the drawer without positively engaging the CD. The two sides of the tray are identical, and the drawer includes a second door which cooperates with a boss on the second side of the tray to hold a second CD in the drawer. Thus, each drawer holds two CDs.

This invention relates to holders or cases for compact disks and diskettes, and, in particular, to a streamlined or thin case which can hold up to 12 compact disks and several diskettes.
Computer programs are more and more frequently being provided on compact disks (CDs). Often the CD is required for operation of the program. That is, the CD contains information which is required for operation of the program. For example, a commonly used CD is a dictionary or encyclopedia, wherein the data for the program is contained on the CD. However, such CDs which are required for the operation of a program are often kept in a drawer with other CDs and diskettes which are required only to load a program onto a computer's hard disk. Generally, a computer user will need to have only a few CDs and diskettes handy for normal day-to-day use. Obviously, the CDs that may be needed will vary from user to user. However, the computer users need to have an easy way to organize the often used CD's so that the CDs are easily accessible. Merely placing the CDs in a traditional disk box is not desirable because the CD will be placed on its edge and can have its information bearing surface in contact with other CDs or parts of the box. All this can damage the CD, ultimately making the CD unusable. Leaving the CD in its jewel box will protect the CD. However, not all executable CDs are provided with jewel boxes. Further, for those that are, there is still the need to organize them in some manner so that they be easily accessible.
CD containers are available which allow a computer user to put CDs together in one location. However, the trays which hold the CDs in the containers are designed around the conventional hub or rosette of conventional jewel boxes. That is, the trays engage the hole or inner edge of the CD to hold the CD in the tray. The forces applied by the hub to a CD which is used daily, and may be placed in, and taken out of, the tray several times a day, may ultimately damage the CD. Although there is no information on the CD at the inner edge of the CD, if the inner edge of the CD is damaged, the CD may none-the-less be rendered unusable.

Compact disk case and compact disk holder therefore


The present invention relates to a process for the production of a powder coating, in which a suspension of powder particles is sprayed and the spray jet is directed onto the substrate to be coated, characterized in that. 1.) a suspension of powder particles in a liquefied gas is employed, the gas having been liquefied under a pressure of not more than 20 bar, and PA1 2.) the liquid gas is vaporized before, during or after the spraying of the suspension.

For a wide variety of areas of application, pulverulent substances are required which have extremely low particle sizes of less than about 20 microns (.mu.m). It is frequently problematic in the case of fine-particled powders of this type that these materials are difficult to handle and, in particular, problems occur with respect to their flowability. Another particular problem is the production of coatings using these fine-particled powders. One example of such an area of application is the sector of catalyst technology, in which the active substances, in addition, have to be introduced into fine pores in the support materials.
A further important area of application for fine-particled pulverulent substances is that of powder coatings, which are gaining increasing importance.
Conventional coating procedures, in which colored pigment particles dispersed in a conventional liquid solvent are sprayed in the form of paint droplets onto the components to be coated, represent considerable environmental pollution because of the contamination of the exhaust air, which is concentrated during, for example, the line production of passenger cars.
In the interests of improved environmental protection, three kinds of coating have been developed for more environmentally friendly spray coating (R. Laible, Umweltfreundliche Lackiersysteme fur die industrielle Lackierung Environmentally Friendly Coating Systems for Industrial Coating!, Expert Verlag, Esslingen, 1988), namely high-solids coatings, water-borne coatings and powder coatings.
High-solids coatings are essentially none other than normal coatings which have been thickened; in other words, the emissions into the surrounding air of solvents of which some are harmful are reduced, but not eliminated. Waterborne coatings have the disadvantage that the overspray in the water has to be recovered. Powder coatings lead neither to significant contamination of the air nor to polluting contamination of water. In its current state of development, however, this process has a number of disadvantages which stand in the way of its broad application, especially in the sector of the thin coating of thin metal components of large surface area, for example vehicle bodies.
The principle of electrostatic powder coating, which has been introduced since 1965, is very simple. A powder coating comprises particles of colored powder dispersed in air which have a particle-size range of from 20-60 .mu.m with average particle sizes of from 40-50 .mu.m. When dispersed in air (fluidized), such powder coating particles have the flow characteristics of a fluid. This property is the reason why they can be used in spray painting. They are charged in special electrostatic spray guns and sprayed onto an earthed workpiece to which they adhere electrostatically. Particles of powder coating which have been sprayed past the workpiece and have not been deposited are suctioned off, separated from the air, screened and re-used.
The advantages of powder coating are consequently that virtually no environmental pollution occurs and that the utilization of material which can be achieved, by dry suction and separation, is very good, since overspray is recovered without troublesome residues.
The ability to utilize this powder coating technology is, however, restricted to the application of relatively thick coats of at least 70 .mu.m since, in order to have a smooth surface, the coat must be at least about 70 .mu.m thick, and it is not possible to process relatively fine particles using this process without encountering problems.
Known powder coatings belong to a class of bulk material which is capable of holding air. Its characteristics are as follows: a bed of particles of material--cracking catalysts being a typical example--expands on fluidization (fluidized bed) distinctly above the minimum fluidization, before air bubbles start to form in the fluidized bed. If the supply of air is cut off suddenly, then the bed collapses slowly at a rate of from 0.3-0.6 cm/s, corresponding to the empty-tube velocity in the suspension phase.
A type of bulk material comprising particles below about 20 .mu.m, which includes materials which are noticeably cohesive, i.e. in which the adhesive forces between the particles significantly exceed the other possible forces in the fluidized bed, namely weight and flow resistance, permits more or less poor fluidization only with the additional use of, for example, mechanical stirrers, although hardly achieving true dispersion of the particles.
Powder coatings have a solids density of about 1500 kg/m.sup.3. At atmospheric pressure, the density of air is negligible. Only a particle-size distribution of the powder coatings within the range between 20 .mu.m and 60 .mu.m guarantees that powder coatings will be in the region of the excellent fluidization properties required. The consequence of this lower particle-size limit is, therefore, that it is not possible to go below certain minimum layer thicknesses, and that high surface quality, leveling and gloss are only achieved at layer thicknesses >70 .mu.m, i.e. with high paint consumption and thick coats of paint.
A significantly broadened range of applications for the known powder coating technology in order to give thinner coatings of high quality would necessitate powder coating particles of an unsuitable bulk material type containing particles below about 20 .mu.m. Prior-art powder coating technology is therefore denied access on physical grounds to desirable low particle size ranges. Important areas of application--for example catalyst production, in which the active substance is introduced into the pores of a support substance--are also closed to this technology.
Moreover, present-day powder coating technology is restricted to a number of selected binder/curing agent systems because, for example, reactive systems are not accessible to powder coating technology. For instance, it is not possible to formulate powder coatings as two-component systems in which the curing agent and the binder are stored separately and are mixed only shortly before application. In fact, to obtain homogeneous powder coatings, specific process steps are necessary in the production of the powder coatings. Conventionally the powder coating is first extruded and is only then ground, so as to guarantee a homogeneous distribution of the individual components of the powder coating. In contrast, it is not possible to produce a powder coating having homogeneous distribution of the individual components simply by dispersing them. Consequently, it is not possible to produce powder coatings at the actual premises of the user from a binder component and a curing-agent component. It is for this reason that it is not possible to formulate powder coatings which contain components which are reactive at ambient temperature, for example OH group-containing binders and curing agents which are reactive at ambient temperature and are based on free isocyanate groups.
In addition, the extrusion step which is necessary in the conventional processes for the production of powder coatings is time-consuming and cost-intensive. Furthermore, in the case of reactive systems, it is quite possible for problems to occur during extrusion (premature reaction), once again necessitating appropriate and laborious measures.
A further reason why powder coating technology is restricted to a number of selected binder/curing agent systems is that the present-day powder coatings must have glass transition temperatures Tg of >40.degree. C., so as to ensure the resistance to agglomeration of the powder coatings. Indeed, the powder coatings are in general capable of being stored at ambient temperature (generally 25.degree. C.) and of remaining free-flowing if the glass transition temperature of the powder coatings is above the ambient temperature.
The technical problem on which the invention is based, starting from the fact that powder coating represents the only truly environmentally friendly coating process, and in view of the above-described limitation of present-day powder coating technology, is to broaden the scope of application of powder coating technology. Hence it should also be possible to produce relatively thin coatings with a very high surface quality and hiding power in combination with perfect leveling and gloss, without causing any new kind of environmental pollution. In addition it is intended to provide powder coatings based on an expanded range of binder/curing agent. A particular intention is to enable the formulation of powder coatings on the basis of reactive systems, i.e. binder/curing Agent systems which are reactive even at ambient temperature. Finally, it is intended to open up completely new areas of application to powder coating technology, for example the sector of catalyst production.
A process solving this problem is characterized along with developments thereof in the patent claims. Also indicated in the patent claims is a grinding process for the production of the powder to be employed in accordance with the invention, and a powder suspension which is suitable for the powder coating process.
Finally, the invention relates to the application of this process to the production of catalysts.
It is surprising and was unforeseeable that the suspension of various finely divided materials in gas liquefied under a pressure of not more than 20 bar would give suspensions which permit problem-free management and can be employed in a very wide range of sectors. For instance, the suspension according to the invention in the gas liquefied at a pressure of not more than 20 bar can be employed advantageously for all materials which can readily be suspended in the liquefied gas.

Process for the production of a powder coating, apparatus for carrying out the process, and powder formulation for carrying out the process


An IP connection processing device and, more particularly, an IP connection processing device that, upon completion of user authentication, initiates a connection to an IP network in a designated area constructed by a wireless LAN or the like. The IP connection processing device, which processes the connection to the IP network that requires user authentication for connection to the network, includes components for: detecting authentication completion; acquiring an authentication result; and initiating or resuming the IP connection processing upon detection of the authentication completion. The IP connection processing device, upon detection of the authentication completion, requests IP address information from the IP network, and acquires an IP address of its own based on the information returned by the IP network.

1. Field of the Invention
The present invention relates to an IP connection processing device and, more particularly, to an IP connection processing device that, upon completion of user authentication, initiates a connection to an IP network in a designated area constructed by a wireless LAN or the like.
2. Description of the Related Art
Wireless LAN is one of the technologies that have been attracting attention, in recent years, due to the explosive proliferation of the Internet. Originally, the wireless LAN was developed as a technology for constructing a LAN environment in offices by using wireless connections. In recent years, however, a wireless LAN service called the "hot spot service" has been spreading which offers customers high-speed Internet access from public spaces such as railway stations and coffee shops by installing wireless LANs in such locations.
The packet communication speed of the wireless LAN is 11 Mbps based on the IEEE 802.11b specification. This is overwhelmingly faster than the maximum speed of 28.8 Kbps of the second generation mobile communication system PDC-P or the maximum speed of 384 Kbps of the third generation mobile communication system IMT-2000 (W-CDMA communication system).
Further, the hot spot service using wireless LANs employs flat fee billing plans, and thus offers cost advantages over the above-mentioned conventional systems which employ usage-based billing plans. Under the current circumstances, the hot spot service can only be used in limited areas, but this problem will be solved soon as the service areas are expanded to cover large areas where people gather.
The current hot spot service is based on the Internet Protocol version 4 (IPv4). However, with rapidly increasing numbers of terminals on IP networks in recent years, there is a concern that the IPv4 address space will soon be exhausted, and it is expected that the hot spot service will also transfer to the Internet Protocol version 6 (IPv6) that provides a greatly expanded address space.
FIG. 1 is a diagram showing one example of a network constructed using a wireless LAN and IPv6. The following description is given by taking the hot spot service as an example.
In FIG. 1, an IP terminal 10 is a notebook PC, PDA, or the like that has a capability to communicate with the wireless LAN. The IP terminal 10, for example, on the move, is connected to a wireless LAN access point (AP) 21 installed at a railway station or a coffee shop.
The access point 21 covers a hot spot area 20 within a prescribed range from the access point 21, and provides services, such as high-speed Internet connection service and an information service limited to that area, to the IP terminal 10 located within the hot spot area 20.
The access point 21 is connected to an access router (AR) 31, to which it is subservient, for connection to the Internet 40 via an operator network 30. The access router 31 is installed at a designated location, for example, within a station or a department store, or at an Internet service provider (ISP), a telephone switching office, or the like. The operator network 30 is constructed by interconnecting a plurality of such access routers.
An authentication server 32, which is installed at a particular location within the operator network 30, centrally processes user authentication of every IP terminal 10 located in each hot spot area 20. The IP terminal 10 whose user identity is authenticated by the authentication server 32 is permitted to access the Internet 40 and to perform communications such as Internet telephone (Voice over IP) with a corresponding node 41 by utilizing the high speed capability of the wireless LAN.
FIG. 2 is a diagram showing one example of an IPv6 connection sequence on the wireless LAN. FIG. 3 shows router advertisement message format.
In FIG. 2, when the IP terminal 10 moves into the hot spot area 20, it detects radio waves being radiated from the wireless LAN access point 21 (S101). Thereupon, the IP terminal 10 initiates connection processing (association) with the access point 21 (S102).
When a connection request is received from the IP terminal 10, the access point 21 requests the authentication server (RADIUS server) 32 to process the user authentication of the IP terminal 10 (S103). When the user authentication is successfully done, the IP terminal 10 is notified accordingly (S104) and, at the same time, the access point 21 opens its port and allows the IP terminal 10 to access the IP network (S105).
Thereafter, when the IP terminal 10 receives a router advertisement message that the access router 31 is broadcasting periodically (S106) (refer, for example, to Document 1), the IP terminal 10 generates its own IP address to be used within the hot spot area 20 where it is located, by using the route prefix contained in the user prefix field (Prefix) of the router advertisement message shown in FIG. 3 (S107) (refer, for example, to Document 2).
Using this IP address, the IP terminal 10 initiates communication based on IPv6 with the correspondent node 41 via the IP network including the Internet 40, etc. (S108). IPv6 is defined by its standardization body IETF (Internet Engineering Task Force) (refer, for example, to Document 3).
The predominantly used wireless LAN authentication method is based on IEEE 802.1x defined by its standardization body IEEE (Institute of Electronics and Electrical Engineers). The standard includes authentication mechanisms such as EAP-TLS (Extensible Authentication Protocol—Transport Level Security), EAP-TTLS (Tunneled TLS), PEAP-TLS (Protected EAP protocol), EAP-MD5, or the like.
The authentication based on IEEE 802.1x is implemented by three nodes, i) node (IP terminal) that requires authentication for network access, ii) node (AP) that controls the network access at packet level, and iii) node (authentication server) that permits the network access. The above-described configuration is based on such node configuration.
FIG. 4 shows one example of a prior art configuration for IP connection processing in the IP terminal 10.
In FIG. 4, an interface section 11 performs wireless communication with the access point (AP) 21 by using a prescribed wireless communication scheme. A kernel section 12 shows the kernel section of a conventional IPv6-compliant operating system (OS), and contains an authentication processing section 14 and an IP processing section 13.
The authentication processing section 14 performs user authentication processing with the authentication server 32 via the access point (AP) 21. The IP processing section 13, upon receiving the first router advertisement message after successful completion of the user authentication, generates its own IP address by using the route prefix contained in the message. The sections 13 and 14 each operate individually in accordance with the connection sequence shown in FIG. 2.
In wireless LAN environments that provide hot spot services, there is an increasing need to support handover (switching from one access point to another) which occurs when the user moves around. According to the above-described wireless LAN, the communication session is not disconnected when effecting switching from one access point to another within the same IP subnet (served by the same access router).
However, in the case of access point switching across different IP subnets (served by different access routers), the communication session is disconnected and the IP connection processing has to be initiated once again, because the IP address of the IP terminal 10 changes. As a result, Mobile IP technology that can achieve mobility that does not involve communication disconnections in a wireless LAN environment becomes important. Mobile IP is a mechanism for managing mobility at IP level, and has the advantage that the communication session will not be disconnected even if the IP address changes, as will be described in the following example.
FIG. 5 is a diagram showing one example of another network constructed using a wireless LAN and IPv6. The following description is given by taking Mobile IPv6 as an example.
The only differences between FIG. 5 and the previously given FIG. 1 are that the IP terminal 10 in FIG. 1 is referred to as a mobile node (MN) 10′ in FIG. 5, and that a home agent (HA) 42 is connected to the Internet 40 in FIG. 5. Though differently named, the IP terminal 10 and the mobile node (MN) 10′ actually have the same functions.
The home agent 42 manages the location (area) of the mobile node 10′. For this purpose, the mobile node 10′ has a permanent IP address (HoA: Home Address) unique to it and an IP address (CoA: Care of Address) which is generated when the mobile node 10′ has moved into an area served by another access router (AR) 31.
The mobile node 10′ notifies the generated IP address (CoA) to the home agent 42 which then updates the current IP address (CoA) to the IP address (CoA) thus notified. By so doing, communication with any destination mobile node 10′ is performed by way of the home agent 42 by using the permanent IP address (HoA) of that destination mobile node 10′ regardless of its current location.
The home agent 42 that received data with the permanent IP address (HoA) attached thereto forwards the data through tunneling by attaching the IP address (CoA) of the area where the destination mobile node 10′ is currently located. Similarly, the destination mobile node 10′ performs communication with the originating mobile node 10′ by way of the home agent 42 by using the permanent IP address (HoA) of the originating mobile node 10′.
FIG. 6 is a diagram showing one example of a Mobile IPv6 handover sequence in the wireless LAN environment.
In FIG. 6, the mobile node 10′ is communicating with a corresponding node (CN) 41′ by way of the home agent 42 in the area served by the current access point (current AP) 21 (S201). Next, the mobile node 10′ moves to a new area and detects radio waves being emitted from another access point (new AP) 21′ (S202 and 203). Thereupon, the mobile node 10′ initiates connection processing (association) with the new access point 21′ (S204).
The user authentication processing carried out in the subsequent steps S205 to 209 is the same as that carried out in the previously described steps S103 to 107 in FIG. 2. Next, the mobile node 10′ notifies the home agent 42 of the IP address (CoA) of its own generating by sending a Binding_Update message (S210). In response, the home agent 42 updates the current IP address (CoA) to the new one, and notifies the mobile node 10′ of the completion of the updating by returning a Binding_Acknowledgment message (S211).
The mobile node 10′ then resumes communication in the area served by the new access point 21′ and continues communication with the correspondent node (CN) 41′ by way of the home agent 42 (S212). As the home agent 42 centrally performs updating management and switching control as described above, the communication session is not disconnected even when the IP address is changed.
The Mobile IP standardized by IETF RFC 2002 is based on IPv4 (refer, for example, Document 4) but, as the basic operation of the Mobile IPv6 is the same as that of the Internet Draft Mobile IP based on IPv6, the above example has been described for the case of the Mobile IPv6.
Document 1: Internet<www.ietf.org/rfc/rfc2461.text>
Document 2: Internet<www.ietf.org/rfc/rfc2462.text>
Document 3: Internet<www.ietf.org/rfc/rfc2460.text>
Document 4: Internet<www.ietf.org/rfc/rfc3344.text>
The network configuration using the wireless LAN and IPv6 shown in FIG. 1 has had the problem that it takes much time to process IPv6 connections in the wireless LAN environment that requires user authentication. The reason is that, as shown in the IPv6 connection sequence of FIG. 2, even when the user authentication is done successfully, and is ready to initiate communication (S105), the IP connection processing is not initiated until the router advertisement message is received from the access router 31 (S106 to 108).
RFC 2461 "Neighbour Discovery for IPv6" standardized by the IETF defines the time interval at which the router broadcasts the router advertisement message. According to the definition, the default interval is once in every 198 seconds, and the minimum interval is once in 3 seconds. This means that, depending on the transmission timing of the router advertisement message, there is a delay of several seconds to about 3 minutes from the completion of the user authentication to the reception of the router advertisement message.
This has resulted in the problem that, despite successful completion of the user authentication, IP communication using browser or communication applications on the IP terminal 10 cannot be initiated. This problem has been attributed not only to the delay in receiving the router advertisement message from the network side, but also to the IP connection processing configuration of the prior art IP terminal 10.
As explained for the prior art configuration shown in FIG. 4, in a conventional IPv6-compliant operating system (OS) the authentication processing section 14 and the IP processing section 13 contained in the kernel each operate individually in accordance with the connection sequence shown in FIG. 2. Accordingly, when the user authentication processing is completed, the authentication processing section 14 terminates its process, and the IP connection processing is initiated by using the reception of the router advertisement message as a trigger.
In this way, the prior art configuration does not have any means for actively requesting the network for an early transmission of the router advertisement message, or if such means is provided, the authentication processing section and the IP processing section are not configured to operate in a cooperative manner; accordingly, if a request packet (router solicitation) is transmitted before completion of the authentication, the packet will be discarded at the access point (AP), leaving no choice but to wait until the router advertisement message is received.
This problem becomes more serious when mobility is added to the IP terminal 10. This is because, as the mobile terminal 10 moves, the access router 31 on the network side frequently changes and, each time this happens, the communication in progress is disconnected and the IP connection processing, including the user authentication processing, is requested once again. In view of this, in the example of FIG. 5, the network configuration based on the Mobile IPv6 is used in the wireless LAN environment, in an attempt to prevent communication disconnections associated with IP address changes.
However, as is apparent from the IP connection sequence of FIG. 6, in the current wireless LAN environment, reconnection processing at IPv6 level, including the user authentication processing, necessarily occurs when the mobile node moves across different access routers. Accordingly, if it takes much time to complete the processing, a similar problem to that in the example of FIG. 1 can occur even when the Mobile IPv6 is employed.
For example, if the processing time becomes too long, the communication with the correspondent node 41′ is disconnected. Further, if a handover occurs while the user is in the process of communication, the application program is temporarily shut off and remains off until the IP communication is resumed; in particular, in the case of a realtime application such as Internet telephone (VoIP) or a video stream, a prolonged non-communication time causes a serious problem.
The above problem becomes more serious when the user authentication processing is performed using encrypted packets as in PEAP-TLS. In this case, as the reception of an authentication packet has to be followed by the process of deciphering the result of the authentication, there has been the problem that high-speed handover becomes difficult because of increased delay in recognizing the successful completion of the authentication.
In the above cases, there is a need to further enhance the speed of the IP connection processing in the wireless LAN environment by reducing the processing burden on an access point (AP) which is accessed by a plurality of users.


A method for forming a fine pattern of a semiconductor device comprises the steps of: forming a first hard mask pattern having a width of W1 and a thickness of T1 over an underlying layer formed over a semiconductor substrate; forming a second hard mask film with a planar type over the resulting structure and planarizing the second hard mask s to expose the first hard mask pattern; removing the first hard mask pattern by a thickness T2 from the top surface (0<T2<T1); performing a trimming process on the second hard mask film to form a second hard mask pattern having a slope side wall; performing a second trimming process on the second hard mask pattern to separate the second hard mask pattern from the first hard mask pattern and form a third hard mask pattern having a width of W2; and patterning the underlying layer using the first hard mask pattern and the third hard mask pattern as etching masks.

The present invention relates to a method of manufacturing a semiconductor device, and more particularly, to a forming method of a hard mask pattern for obtaining fine pattern.
In order to manufacture semiconductor devices that have become smaller, the size of patterns has also become smaller. Research has been made to improve resist and photolithography equipment for obtaining fine patterns.
Although KrF (248 nm) or ArF (193 nm) as an exposure light source have been applied in photolithography, attempts have been made to use short wavelength light sources such as F2 (157 nm) or EUV (13 nm).
However, when new light sources such as F2 or EUV are applied, new exposer equipment is required, which results in increased manufacturing costs. Also, the increase of numerical apertures associated with the new light sources degrades the focus depth width.
Also, it is difficult to manufacture a highly-integrated semiconductor device having a fine pattern because the resolution of the pattern obtained from the exposer equipment using a short wavelength light source is limited to 0.1 μm.

Method for forming fine pattern of semiconductor device


A linear tape drive system includes a tape having a path direction, a data track having data transitions at an azimuthal orientation relative to the path direction, and a servo track having servo positioning transitions. A linear tape drive module is configured to read and/or write to the data track at the azimuthal orientation and read the servo positioning transitions.

1. Field of the Invention
The invention relates to linear tape drive modules for linear tape drive systems.
2. Discussion
Linear tape drive systems may include a tape that has data transitions perpendicular to a path direction of the tape and a pre-recorded servo track having angled transitions relative to the data transitions. Data elements may run parallel to the data transitions and a servo element may run across the angled transitions. By indexing across the width of the tape, the servo allows a head to serpentine within a plurality of defined data bands.
A data read element may be 50% of the width of a written track thus allowing for "off track" wander without intercepting the adjacent written track data. The over-sizing of the written track to compensate for off track wander may limit the number of tracks that can be packed across the width of the tape while keeping the magnetic read element width such that a useful signal may be reliably generated.
Helical scan drives may include several independent single track heads mounted on an angle in a rotating drum which spins in the direction of tape motion without the use of an active servo positioning system reference to the tape. While helical scan drives may have lower data rates due to low read/write element count and lower linear data density, it may offer the advantage of packing tracks horizontally on tape next to, or over lapping, each other due to the data signal cancelling realized when a read element is parallel to the desired track transition and up to perpendicular to the adjacent track transition. This allows the read element to be up to the same size as the written track to increase signal output and maximize horizontal track packing.

Linear tape drive module for a linear tape drive system


A hybrid vehicle includes an engine for producing propulsive forces, an electric motor for selectively generating assistive drive forces in addition to the propulsive forces and generating electric energy converted from the propulsive forces, and an energy storage unit for selectively supplying electric energy to the electric motor and storing electric energy converted by the electric motor. A control system for the hybrid vehicle includes an accelerated/decelerated state detecting unit for detecting an accelerated/decelerated state of the hybrid vehicle, a memory for storing a plurality of fuzzy rules and membership functions to determine an operating state of the electric motor from the accelerated/decelerated state according to a fuzzy inference process, a goodness-of-fit calculator for determining respective goodnesses of fit of the fuzzy rules based on the membership functions from the accelerated/decelerated state as detected by the accelerated/decelerated state detecting unit, a goodness-of-fit combiner for combining the goodnesses of fit as determined by the goodness-of-fit calculating unit to determine an operating state of the motor, and a motor controller for controlling the electric motor based on the operating state of the motor as determined by the goodness-of-fit combiner.

1. Field of the Invention
The present invention relates to a control system for a hybrid vehicle having an engine for generating propulsive forces for the hybrid vehicle and an electric motor for generating assistive forces in addition to the propulsive forces generated by the engine and absorbing the propulsive forces generated by the engine.
2. Description of the Related Art
There has in recent years been developed a hybrid vehicle which has an engine, like an internal combustion engine for ordinary automobiles, as a power source for generating propulsive forces (running drive forces) for the hybrid vehicle and also an electric motor connected to the output shaft of the engine for generating assistive drive forces in addition to the propulsive forces generated by the engine, i.e., applying assistive drive forces to the output shaft of the engine, and for being operated as an electric generator by the engine (regenerative mode) to convert and absorb the propulsive forces generated by the engine as electric energy. To generate the assistive drive forces, the electric motor is energized by electric energy from an energy storage unit such as a storage battery. When it is operated as the electric generator, the generated electric energy is stored in the storage battery.
One such hybrid vehicle is disclosed in Japanese patent publication No. 6-1925, for example. In the disclosed hybrid vehicle, when the driver sets up a motor mode by operating a given switch, the electric motor is controlled to generate assistive drive forces depending on the depth to which the driver presses the accelerator pedal. When the driver sets up a regenerative mode by operating a given switch, the electric motor is controlled to generate electric energy for applying braking forces depending on the position of the switch, and part of the generated electric energy is stored in the storage battery.
Since the assistive drive forces produced by the electric motor are determined simply by the depth to which the driver presses the accelerator pedal, when the depth to which the driver presses the accelerator pedal is abruptly changed, the assistive drive forces produced by the electric motor are also abruptly changed. Therefore, the behavior of the hybrid vehicle as it runs tends to be sluggish. Furthermore, since a discharged current of the storage battery is also abruptly changed when the assistive drive forces produced by the electric motor are abruptly changed, the storage battery is apt to be short in service life.
In the motor mode, the electric motor does not generate electric energy. Therefore, the stored energy of the storage battery tends to be reduced, with the result that the storage battery will fail to supply enough energy to the electric motor, which will then fail to produce sufficient assistive drive forces. Inasmuch as the electric motor produces assistive drive forces only when the driver sets up the motor mode with the switch, if the driver forgets to operate the switch or keeps the regenerative mode turned on, then the electric motor cannot produce desired assistive drive forces.
In the regenerative mode, the braking forces produced by the generation of electric energy with the electric motor are determined by the position to which the switch is shifted by the driver. Therefore, if the driver does operate the switch properly, then the electric motor may produce smaller braking forces than would be necessary or larger braking forces than would be necessary.
Because the amount of generated electric energy which governs the braking forces is determined by the position to which the switch is shifted by the driver, the electric motor may possibly generate too a small amount of electric energy while the stored energy of the storage battery is small, and the stored energy of the storage battery may remain insufficient. Conversely, the electric motor may possibly generate too a large amount of electric energy while the stored energy of the storage battery is large, and the excessive electric energy may be wasted.


The invention concerns a process for the selective hydroisomerisation of compounds containing at least one n-alkane chain containing more than 10 carbon atoms, in which the compound to be treated is brought into contact with a catalyst comprising at least one hydro-dehydrogenating element and at least one molecular sieve with a mono- or bidimensional pore network in which the openings of the accessible pores are delimited by 10 oxygen atoms, and the distance termed the bridge width between the pores is less than 0.70 nm, and in which the catalyst, when subjected to a standard n-heptadecane isomerization test, has a selectivity of at least 70% towards isomerized products for a conversion of 95%.. The sieve is preferably a NU-10, NU-23, NU-87, EU-13 or Theta-1 zeolite.

The present invention concerns a process for selective hydroisomerisation of long (more than 10 carbon atoms), linear and/or slightly branched paraffins, in particular for high yield conversion of feeds with high pour points to at least one cut with a low pour point and a high viscosity index.
High quality lubricants are of fundamental importance for the efficient operation of modern machines, cars and trucks. However, the quantity of paraffins which directly originate from untreated crude and which have the properties to constitute good lubricants is very low when compared with the increasing demand in this sector.
Heavy oil fractions containing large amounts of linear or slightly branched paraffins must be treated to obtain good quality lubricant stock in the best possible yields. A dewaxing operation is used which is intended to eliminate the linear or very slightly branched paraffins from feeds which are then used as lubricant stock or as kerosine or jet fuel.
The linear or very slightly branched high molecular weight paraffins which are present in the oils, kerosine or jet fuel produce high pour points and thus lead to coagulation at low temperatures. To reduce the pour points, these linear or very slightly branched paraffins must be completely or partially eliminated.
The dewaxing operation can be effected by extraction using solvents such as propane or methyl ethyl ketone, using propane or methyl ethyl ketone (MEK) dewaxing. However, such techniques are costly, long and not always easy to carry out.
Catalytic dewaxing, as opposed to solvent dewaxing, is more economical and can produce products with the desired physico-chemical properties. This is achieved by selective cracking of the longest linear paraffin chains which leads to the formation of lower molecular weight compounds, a portion of which can be eliminated by distillation.
Because of their form-selectivity, zeolites are among the most widely used dewaxing catalysts. The idea that anticipated their use is that zeolite structures exist in which the pore openings are such that they allow long linear or very slightly branched paraffins to enter their microporosity but branched paraffins, naphthenes and aromatics are excluded. This phenomenon thus leads to selective cracking of linear or very slightly branched paraffins.
Zeolite based catalysts with intermediate pores such as ZSM-5, ZSM-11, ZSM-12, ZSM-22, ZSM-23, ZSM-35 and ZSM-38 have been described for use in catalytic dewaxing by cracking.
Processes using those zeolites can achieve dewaxing by cracking of feeds containing quantities of less than 50 weight % of linear or very slightly branched paraffins. However, with feeds containing higher quantities of these compounds, cracking leads to the formation of large quantities of lower molecular weight compounds such as butane, propane, ethane and methane, which considerably reduces the yield of the desired products.
In order to overcome these problems, we have concentrated our research on the development of catalysts (preferably non ZSM) which could bring about isomerisation of these compounds.
A number of patents exist in this field, for example International patent application WO 92/01657 which describes and claims a process for dewaxing feeds with isomerisation in the presence of a group VIII metal at a hydrogen pressure in the range 100 KPa to 21000 KPa and using a catalyst with a pore opening in the range 0.48 nm to 0.71 nm and in which the crystallite size is less than 0.5 .mu.m. The catalyst leads to improved performances as regards yield with respect to prior art catalysts.

Process for the selective hydroisomerization of long linear and/or slightly branched paraffins using a catalyst based on a molecular sieve