An ionomer and a process for forming the ionomer such that the ionomer has (1) low equivalent weight (below 950, preferably between 625 and 850, and most preferably between 675 and 800) and (2) high conductivity (greater than 0.13 S/cm). In another embodiment, the invention is an ionomer having (1) low equivalent weight (below 950, preferably between 625 and 850, and most preferably between 675 and 800) and (2) acceptably low hydration (less than about 120 weight percent). These ionomers are capable of being processed into thin film and are extremely well-suited for low humidity or high temperature fuel cell applications.

Solid polymer ionic membranes or films have been well known in the art for many years. These polymers are typically characterized by high ionic conductivity, i.e., rapid transport of ionic species, for example, protons. Additionally, it is desirable for such ionically conducting polymers to be made in the form of membranes or thin films. In so doing, the resistance to ionic transport, which is a function of the film thickness, can be reduced. Fluoropolymer compositions are particularly desirable for such uses, and are disclosed, for example, in U.S. Pat. Nos. 3,282,875, 4,358,545 and 4,940,525.
The instant invention relates to ionomers, which as used herein means a perfluorinated polymer containing acid groups or acid derivatives easily converted to acid groups such that the acid form of the polymer in membrane form has a room temperature ionic conductivity greater than 1×10−6 S/cm. As used herein the acid form of an ionomer means that substantially all the ion exchange groups, e.g., SO3—or sulfonic groups, are protonated. One important parameter used to characterize ionomers is the equivalent weight. Within this application, the equivalent weight (EW) is defined to be the weight of the polymer in acid form required to neutralize one equivalent of NaOH. Higher EW means that there are fewer active ionic species (e.g., protons) present. If it takes more of the polymer to neutralize one equivalent of hydroxyl ions there must be fewer active ionic species within the polymer. Because the ionic conductivity is generally proportional to the number of active ionic species in the polymer, one would therefore like to lower the EW in order to increase conductivity.
Lowering the equivalent weight has previously not been a practical approach to making useful membranes. This is because with fluoropolymers currently known, as the equivalent weight goes down, the amount of water (or solvent) that the polymer absorbs goes up. The amount of water absorbed by the polymer is called the degree of hydration or hydration. It is expressed as the weight percent of water absorbed by the polymer under a given set of conditions, for example, after immersion in room temperature water for two hours. A higher degree of hydration is desirable up to a point because it tends to increase the ionic conductivity of the membrane. Correspondingly, lowering the degree of hydration has traditionally meant decreasing the conductivity. But there is a limit to the amount of water or solvent such fluoropolymer membranes can contain. If too much water is present, the film may lose much of its physical integrity, becoming gel-like with little or no rigidity. In the extreme, the polymer may completely disintegrate. In addition, depending on the exact polymer composition, low EW fluoropolymer ionomers may even partially or completely dissolve in water. Furthermore, even if the films were stable, too high a hydration would tend to dilute the number of ions present for conduction, thereby lowering the ionic conductivity. Thus, there is an optimal degree of hydration that is high enough to provide the highest possible conductivity, while not so high that the films become physically unstable when hydrated.
Thus, one would like to decrease the equivalent weight of these fluoropolymers to increase their conductivity, but heretofore could not practically do so because the degree of hydration and/or water solubility was too high to form practical membranes.
Various approaches have been used to circumvent this limitation. In U.S. Pat. Nos. 5,654,109, 5,246,792, 5,981,097, 6,156,451, and 5,082,472 various forms of layered composite membranes are suggested. In '109, the use of a bilayer or trilayer composite ion exchange membranes is suggested where the outer layer or layers are lower equivalent weight for improved electrical performance, while the core layer has a higher EW that provides strength. A similar approach is suggested in '792, but the films are layers are characterized by their glass transition temperatures instead of EW. Three or more layers with variable ion exchange ratio (a parameter proportional to EW) are proposed in '097. In '472 a process to form a membrane is taught whereby a perfluorinated ionomer is laminated to a porous expanded PTFE membrane, followed by impregnation of a low equivalent weight ionomer (e.g., 920–950 EW) into that laminate. Because the impregnation is performed with a solution with low solids content (e.g., 2%), the amount of low equivalent weight material in the final product is relatively low. Although each of these approaches may offer some improvement over the a monolithic single layer fluoropolymer membrane, they all involve the use of rather complex, composite, multilayer structures that can be difficult and/or expensive to process.
Approaches to modifying the fluoropolymer itself have also been taught, for example in U.S. Pat. No. 4,358,545 to Ezzell. The properties of these polymers are described in Moore and Martin, "Morphology and Chemical Properties of the Dow Perfluorosulfonate Ionomers", Macromolecules, vol. 22, pp. 3594–3599 (1989), and Moore and Martin, "Chemical and Morphological Properties of Solution-Cast Perfluorosulfonate Ionomers", Macromolecules, vol. 21, pp. 1334–1339 (1988). The approach described in these references is to produce ionomers with shorter side chains along the polymer backbone. This approach is particularly desirable for use in coating processes (for example, as described in U.S. Pat. Nos. 4,661,411 and 5,718,947) but still suffers limitations for use as fluoropolymer ionomer membranes. In particular, these polymers can still be difficult to form into acceptably thin, strong membranes from solution.
Another approach as described by various authors is to form co-polymers of tetrafluoroethylene and ionomers using variations of the well-known emulsion polymerization (for example, the process disclosed in U.S. Pat. No. 3,282,875). In U.S. Pat. No. 5,608,022 to Nakayama et. al. and WO 00/52060 to Bekarian, et. al., processes are taught to form functionalized, fluorinated co-polymers by dispersing fine droplets of a fluorinated co-monomer before polymerizing with a traditional fluorine containing monomer, e.g. tetrafluoroethylene. In these processes, the formation of fine droplets of the co-monomer is a key to a successful preparation of the polymer. In WO 94/03503 to Barnes, et. al. the rate of addition of the tetrafluoroethylene monomer to the ionomer emulsion is controlled by either altering the concentration of the emulsion during polymerization, varying the pressure of the tetrafluoroethylene gas during reaction, or varying the agitation of the reaction mixture. Barnes teaches that these approaches result in a product with higher utilization of the ionomer as determined by the property of equivalent weight distribution, which he defines as a ratio of EW determined by means of titration to that determined by nuclear magnetic resonance. Barnes et. al. claims that this higher utilization leads to a higher Relative Hydration Product and higher Specific Conductivity. Both these parameters were evaluated in the presence of 2.5 Molar sulfuric acid (2.5 M H2SO4), and therefore are not relevant to the current application where only hydrated polymer in the presence of water is considered.
In yet another approach taught in PCT WO 00/79629 an ionomeric polymer is intimately mixed with a structural film-forming polymer, such as a terpolymer of tetrafluoroethylene, hexafluoropropylene and vinylidene fluoride (e.g., THV series available from Dyneon Corp., Oakdale, Minn.). It then is possible to form acceptably thin films using low equivalent weight ionomers. But, the degree of hydration is still relatively high, 80–110%, when 800 EW starting ionomer is used (e.g., Table 1 in WO 00/79629). Thus, these films might be expected to be relatively weak because of the high hydration.
Finally there is also a large body of art that describes approaches to forming non-ionomeric fluoropolymers. For the most part, this art is not relevant to the instant invention described here because the products produced do not have substantial ionic conductivity, i.e., the ionic conductivity of these products is less than about 1×10−6 S/cm at room temperature.
Fluoropolymer ionically conducting membranes have been utilized in many different applications. One application that has been widely suggested is as electrolytic cell membranes for the electrolysis of sodium chloride as disclosed, for example, in U.S. Pat. Nos. 4,358,545, 4,417,969, and 4,478,695. Additionally, this generic class of polymers, described as fluoropolymer ionomers, have been proposed for use as coatings as described above in US. Pat. No. 4,661,411 to Martin et.al.; as wire insulation (e.g., in WO 90/15828); as replacements for acid catalysts, primarily in organic synthesis as described in "Perfluorinated Resin sulfonic Acid (Nafion-H (R)) Catalysis in Synthesis", by Olah, G. A., Iyer P. S. and Surya P. G. K., in Journal: Synthesis (Stuttgart), 1986 (7) 513–531, and in "Perfluorinated Resin sulfonic acid (Nafion-H) Catalysis in Organic Synthesis" by Yamato, T., in Yuki Gosei Kagaku Kyokaishi/Journal of Synthetic Organic Chemistry, volume 53, number 6, June 1995, p 487–499; as a membrane for water electrolysis as described in Yen, R. S., McBreen, J., Kissel, G., Kulesa, F. and Srinivasan, S. in the Journal of Applied Electrochemistry, volume 10, pg. 741, 1980; as a membrane for electrowinning as described, for example, in "The Use of Nation-415 Membrane in Copper Electrowinning from Chloride Solution" by Raudsepp, R., and Vreugde, M., in CIM Bulletin, 1982, V75, N842, P122; in metal ion recovery systems as described in product literature of Nafion® perfluorinated membrane case histories, DuPont Company, Polymer Products Department, Wilmington, Del. 19898; as a tube to continuously and very selectively dry wet gas streams (see product literature from Perma Pure, Inc., Toms River, N.J.); and as components in polymer electrolyte membrane (PEM) fuel cells. In the latter case, they can function both as the electrolyte or a component thereof, for example as described in by Bahar et.al. in U.S. Pat. Nos. 5,547,551 and 5,599,614; and/or as a component in one or both of the electrodes of the MEA.
When the ion conducting polymers, or ionomers, are used as the electrolyte in PEM fuel cells they conduct protons from one electrode to the other. A common problem associated with such fuel cells is that contaminants such as carbon monoxide tend to poison the catalysts used in the MEA. These contaminants can interfere with the flow of ions between the electrodes and thus degrade the performance of the fuel cell.
One way to reduce the effect of carbon monoxide is to operate the fuel cell at an elevated temperature. This reduces the formation and/or increases the destruction rate of potential contaminants and thereby allows more efficient electrode performance.
The problem with running at high temperatures, however, is that it vaporizes liquid water within the fuel cell, and in so doing, tends to reduce the degree of hydration in the membrane. As described above, decreasing the hydration lowers the ionic conductivity, thereby reducing the efficiency of ion transport through the membrane and adversely affecting fuel cell operation. In fact, at lower temperatures, in PEM fuel cells using conventional ionomers, the incoming gas streams are usually well-humidified in order to maintain a relatively high degree of hydration. Only by adding the additional water in the form of humidity in the gases can the hydration be kept high enough to allow efficient fuel cell operation for long periods of time. However, as the temperature gets close to, or above, the boiling point of water this approach becomes difficult and inefficient. Thus, an ionomer with relatively low hydration and acceptably high ionic conductivity would require less ambient water to function as the electrolyte in PEM fuel cells. It could function efficiently both in lower humidity environments at lower temperatures, as well as at temperatures closer to and even potentially above the boiling point of water.
As described above, the known low equivalent weight ionomers have a relatively high hydration. They are also known to be partially or completely soluble in water as well. These factors would counsel against their use in environments where water is produced, e.g. hydrogen-oxygen fuel cells, because these polymers tend to become physically unstable in these environments. In addition, as described above and shown recently (WO 00/52060, Table 1) the ionic conductivity decreases as the equivalent weight goes down concomitant with a large increase in hydration. The ionic conductivity reported in WO '060 decreases by more than 30% when the equivalent weight of the subject ionomer is reduced from 834 to 785.
Against this background of conventional wisdom, applicants have discovered a low equivalent weight ionomer that has a combination of relatively high ionic conductivity and relatively low hydration, As a result, this invention makes possible the more effective use of solid fluoropolymer membranes in existing applications such as those described above. Additionally, new applications heretofore not practical may become possible with this new, unique set of characteristics. The instant invention is particularly valuable as an electrolyte or component thereof, or as a component in the electrode of polymer electrolyte membrane fuel cells operating at high temperatures or low humidities.


An object of the present invention is to achieve lower NOx combustion in response to the increasingly intensified NOx regulations for burners. The present invention provides a low nitrogen oxides generating combustion method and apparatus which utilizes effective self-induced exhaust gas recirculation before the initiation of the combustion of diffusion flames, or allows part of the combustion gas to be entrained by auxiliary fuel flow, air flow and fuel flow before the formation of the diffusion flames to further intensify the recirculation flow of the combustion gas by the diffusion flames or, in addition, which can achieve rich and lean combustion in the diffusion flames for decreasing the generation of NOx by a combination of these measures, and which are excellent in flame stability even in a low temperature atmosphere.

The regulations against the emission of NOx caused by combustion are intensified year after year, and very active technical challenges to decrease NOx emissions are being conducted. NOx generated by combustion includes fuel NOx, prompt NOx and thermal NOx. Among these types of NOx, thermal NOx is produced as the nitrogen molecules in combustion air are oxidized in a high temperature atmosphere, and is highly dependent on the temperature. At higher combustion temperatures, NOx production increases sharply. Thermal NOx is produced without fail if the combustion gas contains nitrogen molecules, and especially when a hydrocarbon-based fuel is burned, the NOx emitted is said to be mostly thermal NOx. A number of methods for decreasing NOx are proposed, including multi-stage combustion methods, exhaust gas recirculation methods, and lean combustion methods. It is also proposed to combine these methods in many ways.
In multi-stage combustion methods, the fuel or combustion air is divided for combustion in two or more stages, and it is intended to achieve low NOx combustion by keeping the flame temperature low or keeping the oxygen concentration low. These combustion methods have a problem in that the multi-stage combustion makes the burner complicated. The exhaust gas recirculation methods are intended to lower the flame temperature or lower the oxygen concentration by mixing part of the combustion gas with air or fuel, and includes forced exhaust gas recirculation methods and self-induced exhaust gas recirculation methods. The forced exhaust gas recirculation methods use a recirculation duct and blower to forcibly mix parts of the combustion gas with combustion air or fuel. These are the most general methods. In the self-induced exhaust gas recirculation methods, a specially devised burner is used to have combustion air flow or fuel flow encapture the combustion gas for mixing to achieve the effect of exhaust gas recirculation by the jet entrainment on encapturement. The self-induced exhaust gas recirculation methods have an advantage in that the effect of exhaust gas recirculation can be obtained without forcibly recirculating the combustion gas, and is free from the complication of the multi-stage combustion methods in that the fuel or combustion air is divided into a plurality of lines. A burner adopting a self-induced exhaust gas recirculation method is disclosed, for example, in Japanese Laid-Open No. 87-17506, and many other burners use the self-induced exhaust gas recirculation methods. However, these methods are limited in their capability to decrease NOx and, further, technical development is necessary to meet the latest severe NOx regulations. Combustion methods developed to maximize the advantage of self-induced exhaust gas recirculation are proposed in Japanese Patent Laid-Open No. 89-300103 and 91-91601, and Japanese Utility Model Laid-Open No. 77-61545. These combustion methods are characterized in that combustion air flow and fuel flow are separately and independently injected into a furnace with a burner without any flame stabilizing mechanism to maximize the effect of self-induced exhaust gas recirculation. In this configuration, the flame is not stabilized in the burner, but is formed at a lifted position, and the combustion begins after part of the combustion gas in the furnace has been sufficiently entrained or encaptured by the fuel flow or combustion air flow. In these combustion methods, the flame is a diffusion flame. Since there is no flame stabilizing mechanism, it can happen that unless the temperature is high, stable ignition cannot be achieved. Therefore, even though the methods are suitable for high temperature furnaces, such as heating furnaces and melting furnaces, they have problems in that the amount of unburned fuel increases and a larger furnace must be used for perfect combustion when they are applied to boilers and low temperature heating furnaces.
Another method for reducing thermal NOx is to use a premixed flame. Premixed combustion at a high increase air ratio can significantly decrease NOx, but a high excess air ratio is likely to decrease the efficiency of combustion and heat transfer. Furthermore, the premixed flame is poor which is disadvantageous.
A method of decreasing thermal NOx by combining the premixed combustion with the effect of self-inducted exhaust gas recirculation was proposed in Japanese Laid-Open No. 91-175211. In this combustion method, the flame stabilizer is a special device, and part of the low temperature combustion gas is mixed with the premixture before the premixture initiates combustion to lower the flame temperature, or to lower the oxygen concentration for decreasing NOx. This combustion method and apparatus presented problems which were observed with other premixed type burners, such as an air-fuel mixer is necessary to generate a premixture for premixed combustion, and since a premixture within inflammable limits is used, the flame may go back into the burner or mixer.
Furthermore, there is a problem in that since part of the combustion gas is mixed with an inflammable premixture, which could result in ignition occurring immediately after the mixing between the premixture and the combustion gas, if the mixed combustion gas is high in temperature, the effect of self-induced exhaust gas recirculation cannot be sufficiently used. Therefore, the flame stabilizer must be specially devised to ensure that the premixture is not ignited when the premixture and part of the combustion gas are mixed.
As described above, self-induced exhaust gas recirculation methods have advantages in that the burner can be simple and low NOx combustion is possible, compared with other low NOx combustion methods, such as multi-stage combustion methods and lean premixed combustion methods. In the combustion methods for decreasing thermal NOx by using self-induced exhaust gas recirculation, if the self-induced exhaust gas recirculation is used to the maximum extent for the diffusion flame, the unusable temperature range useable in the furnace is limited, and the useable combustion equipment is also limited, which is disadvantageous. Moreover, the application of self-induced exhaust gas recirculation to the premixed flame has the problem of flame stability peculiar to the premixed combustion, like back combustion, and requires a more specifically devised flame stabilizer, which is disadvantageous.

Low nitrogen oxides generating method and apparatus


A trench (12) of a semiconductor memory cell (1) has an insulation collar (44), which is open toward the substrate (42) on just one side (50). On the other side (52), the insulation collar (44, 47, 55) rises all the way up to the insulation cover (62). There is therefore no need for a shallow trench isolation. The contact (70) which is buried on one side is formed by oblique implantation, for example with N2 or argon, the implantation taking place from a fixedly predetermined direction with an angle of inclination of between 15 and 40°. The implantation substances effect different etching or oxidation properties, etc., of the implanted materials. In combination with this method, it becomes possible to realize a new layout for the semiconductor memory cell (1), in which the structures for forming the active areas form long lines (31) extending over a plurality of adjacent semiconductor memory cells.

In a known embodiment, semiconductor memory cells with random access to information stored in a storage capacitor include, as dynamic memory cells, a planar select transistor and a deep trench in which the storage capacitor is formed. At the planar select transistor, a gate contact is arranged on the substrate surface and is formed directly between two doped diffusion regions at the substrate surface. In this document, the term "gate contacts" is used to refer to all active surfaces of the transistor, i.e., the interfaces of word lines and active areas, which, for example, may be separated from one another only by a very thin gate oxide layer.
A bit line contact, via which an electric charge released by the select transistor can be read from the storage capacitor, is connected to a first of the diffusion regions. The other diffusion region is connected via a buried strap to a conductive material, typically polysilicon, in the trench arranged next to the diffusion region. The conductive material in the deep trench functions as a storage electrode for the capacitor, while, for example, a deeply buried doped plate in the substrate serves as a second capacitor electrode, with a thin dielectric layer located between the two electrodes. A word line controls the select transistor via the gate contact for switching an electrically conductive connection from the storage capacitor to the bit line.
To achieve the highest possible integration densities in a memory cell array, it is generally endeavored to minimize the surface area taken up by an individual semiconductor memory cell. For a memory cell with a planar select transistor, the footprint of the smallest memory cell, which can be fabricated conventionally is 8 F2, where F is the smallest length dimension that it is possible to produce by lithography (minimum feature size) on a wafer. In production installations for memory products, F is currently undergoing a transition from 0.15 μm to 0.13 μm.
The area of 8 F2 results from the sum of the two structures produced by lithography—namely the gate contact and the trench—in a semiconductor memory cell, which for a planar arrangement of the select transistor must be at a distance of approximately 1 F from one another, and the required trench isolation, which isolates the active diffusion areas of the cell from those of an adjacent memory cell.
Semiconductor memory cells according to the prior art with trench and planar select transistor are known, for example, from documents EP 0 908 948 A2 and EP 0 949 684 A2.
FIG. 1 illustrates an example of a layout, which is currently in widespread use for a semiconductor memory cell, with an adjacent cell additionally being included in the figure in order to illustrate their relative arrangement in a memory cell array. The two semiconductor memory cells 1, 2 are arranged mirror-symmetrically about an interface 30, which is perpendicular to the plane of the drawing in FIG. 1. The interface 30 and also the interfaces between the other sides of the memory cells represent their imaginary, logic outer limits and serve to facilitate the assignment of individual structures in a dense, periodic array to the respective memory cells. In the present example, the interface 30 is defined by a mirror plane of the structures assigned to two adjacent memory cells.
In the diagrammatic plan view shown in FIG. 1, the trenches 12, 13 are illustrated in the form of rectangles, as they are formed on a mask for patterning the trenches on the wafer. However, the projected image on the wafer depicts trenches with oval cross-sections 22 and 23, respectively. A gate contact 10, which is connected to a word line WL and forms a transistor, allows electrically conductive connection of the trench 12, via a first diffusion region 14, to a second diffusion region 16, with which contact is made from above, in the plane of the drawing shown in FIG. 1, by a bit line contact 18. The memory cells 1 and 2 share the bit line contact 18 and the second diffusion region 16 and 17. The bit line contact 18 is connected to a bit line BL running in the X direction above the plane of the drawing shown in FIG. 1.
The definition of the diffusion regions 14, 15, 16, 17 in the two cells 1, 2 and of the isolation trench 20 for isolating the active areas of the semiconductor memory cells 1, 2 from further, adjacent semiconductor memory cells (not shown) is achieved by the lithographic projection of precisely one structure 31 into, in each case, two cells in the memory cell array to be formed on the wafer. The bar-like structure 31 is initially formed as a resist mask on the surface so that the shallow isolation trenches 20 (shallow trench isolation, STI) can be formed in the silicon substrate in an etching step. After the resist mask has been removed, an oxide is deposited in the trenches, for example in an HDP process (High-Density Plasma process), and then planarized. Then, the gate contacts 10, 11, the word lines WL and, by implantation with subsequent activation of the diffusion regions 14-17, are formed.
In a conventional method for forming the memory cells 1, 2, first of all the trench is formed in a substrate. A dielectric layer which serves as capacitor dielectric is deposited on the inner wall of the trench. The trench is then filled for the first time with a conductive material. The conductive material, together with the dielectric layer, is etched back, so that the capacitor electrode is formed only in a lower region of the trench. Above the etched-back conductive material which comprises, for example, a polysilicon, an insulation collar consisting of oxide is formed at the trench inner wall in a CVD process. Then, in a second filling process, conductive material is deposited into the trench for a second time using a CVD process and etched back, so that there is a distance of, for example, 100 nm from the top edge of the conductive material to the silicon surface. The insulation collar, which projects above this top edge, is removed in an etching step, so that the trench inner wall, which consists of silicon, is uncovered in an upper region of the trench. Then, a third filling with conductive material, which is now highly doped for outdiffusion under the influence of heat, is deposited.
In the completed memory cell, passive second word lines WLs, which can be used to drive gate contacts of adjacent memory cells (not shown in FIG. 1), run over the trenches 12, 13. Therefore, an insulation layer for the second, passive word line WL running above is required above the conductive material of the third filling in the trenches 12, 13. This is made possible by deposition of an oxide above the conductive material of the third filling in a joint step with the filling of the shallow trench isolation 20.
The shallow trench isolation extends sufficiently deep into the substrate for it to reach the top edge of the insulation collar at the trench inner wall, so that there is no electrically conductive connection produced between the adjacent trenches 22, 23 of two adjacent memory cells. In this context, it should be borne in mind that the shallow isolation trench 20 covers approximately half the diameter of the trench 12, so that a sufficiently large buried strap of the conductive material is still available, for example, in the upper region of the trench 12 to the substrate of the diffusion region 14.
On the other hand, if the structure 31 is positioned inaccurately on the trench structure 12, on the one hand the contact surface at the buried strap may be reduced in size or even prevented altogether if an excessively small overlap region 33 is formed between the structure 31 and the trench structure 12. On the other hand, however, if an excessively large overlap region 33 is formed, an undesired diffusion contact may occur on the opposite side of the trench 12. Consequently, to maintain the quality of semiconductor memory cells according to the prior art of this nature, very high demands are imposed on the positional accuracy and sizes of structures and/or very tight tolerances 32 are required with regard to positional accuracy or critical dimension (CD). However, these demands are becoming increasingly difficult to satisfy using lithographic techniques with the constant decrease in feature size.

Semiconductor memory cell having a trench and a planar selection transistor and method for producing the same


A method and apparatus for generating high quality real random numbers is provided. In particular, the present invention enables a hard disk drive of a computer to function as a generator of high quality real random numbers by monitoring one or more of a disk drive's parameters, wherein such parameters are subjected to environmental effects. The system of the present invention does not require the addition of any hardware not normally associated with a computer. According to one embodiment of the present invention, a parameter of the disk drive is monitored, and after processing and filtering the parameter is provided to an application as a random number. Monitored parameters may include the position error signal of a transducer head with respect to a track, temperature, channel gain, transducer head flying height, etc. According to one embodiment of the present invention, the various other parameters may be combined or used in concert to provide high quality real random numbers.

The generation of perfect random numbers is increasingly important in computer applications. For instance, random numbers are used in connection with computer simulations of real world events, and in connection with encryption techniques. In particular, the increased need for the encryption of sensitive data has led to the need for long strings of high quality real random numbers, preferably generated within a short period of time.
At present, methods for the generation of pseudo-random numbers are available. Pseudo-random number generators generally must be provided with a random "seed" number. The pseudo-random number generator then applies the seed to an algorithm to create a series of numbers. The seed may be obtained from various inputs. For instance, the random seed may be derived from the time interval between user keystrokes on a computer keyboard. However, the series of numbers provided by a pseudo-random number generator is deterministic, and therefore predictable. In addition, the same series of numbers is generated if the same seed is used. Therefore, pseudo-random number generators are not ideal for use in connection with applications requiring or benefiting from the use of high quality real random numbers.
A perfect or real random number is a number selected from a set of numbers such that each number in the set has the same probability of being selected. Furthermore, a random number is unpredictable. Real random numbers may be derived from environmental noise. The generation of random numbers from environmental noise necessarily requires an interface with the environment. At present, random number generators, in the form of specialized hardware that convert environmental noise, such as noise from electrical or radioactive sources, to a digital signal and that can be interconnected to a computer, are available. However, the use of such hardware entails additional costs to the computer user, as the specialized hardware is not normally provided as part of a computer. In addition, such hardware requires an interface with the computer. Random number generators associated with certain computer processors are also available. For example, certain INTEL processors include an integrated random number generator. Such random number generators are believed to be capable of providing random bits at a rate of about 75 kbits/s. However, such processor-based random number generators are not widely available, and they typically require the provision of additional circuitry in the processor that is dedicated to the generation of random numbers.
Other methods for generating random numbers include measuring the time between key strokes entered by the user of a computer or the time required for the user of a computer to move a mouse from one position to another. The use of variations in the rotational velocity of a computer disk drive has also been proposed. However, such methods provide too low a rate of random number generation to be useful in connection with applications requiring long strings of random bits. For instance, the use of variations in the rotational speed of a disk drive, believed to be the fastest of these methods, produces only about 100 random bits per minute.
One application that benefits from long strings of random bits are encryption programs. The use of encryption programs to protect sensitive information is increasingly widespread, as computers are often used to store or transfer such information. In order to safeguard sensitive information from unauthorized access, various encryption techniques have been devised. In order to limit the ability of a cryptoanalyst, or hacker, to discern a pattern or deduce a key used to encrypt a particular set of data, real random numbers are necessary.
The encryption of computer data usually involves the "scrambling" of data using an algorithm and a key that is unique to the person or entity seeking to encrypt the data. The key, which is required to unencrypt the data, may be as many as several thousand bits long. However, to even encrypted data is vulnerable to unauthorized access, particularly where the algorithm or key used to encrypt the data can be narrowed down by a hacker, or cryptoanalyst, to a reduced number of possible keys. If a key can be chosen that is truly random, deducing the key will be much more difficult, as a hacker will be unable to discern a pattern to assist in the recreation of the key.
Other computer applications that can benefit from the use of real random numbers are games and simulations (like Monte Carlo algorithms) of natural phenomena. The use of real random numbers in connection with such applications aids in ensuring that the results obtained are free from any unintentional bias that may skew the results. Therefore, real random numbers can make games more enjoyable and less predictable, and can increase the usefulness of computer simulations.
It would be advantageous to provide a random number generator that produces a relatively large number of high quality real random numbers in a short period of time. In addition, it would be advantageous to provide a generator of high quality real random numbers that did not require the provision of hardware not normally included as part of a computer. Furthermore, it would be advantageous to provide a generator of high quality real random numbers that added little to the cost of a computer and that was reliable in operation.

Method and apparatus for generating high quality real random numbers using a disk drive


A shipping and storage case for a borescope or endoscope has a coil of a tubular low-friction material, such as PVC tubing, to receive the borescope's flexible insertion tube. The coil can be in a form of a flat spiral positioned adjacent one side wall of the shell, or in the form of a helical spiral positioned adjacent the side walls within the case. The coil of tubing provides a convenient way for insertion tubes to be packaged and protected during shipping and storage.

This invention relates to shipping and storage containers, especially for storing elongated flexible tubular probes of the type which can contain delicate or expensive mechanisms therewithin. Borescopes, endoscopes, or other similar probes typically have an elongated flexible insertion tube with an imaging device carried on its distal tip for the purpose of capturing the image of a target object within the viewing field of the borescope. In a so-called fiberscope, a coherent fiber optic bundle carries the image to a viewing device at the proximal end of the insertion tube. In a video scope, a miniature video camera is disposed at the end of the flexible elongated insertion tube, and video images are carried over conductors which extend through the tube to its proximal end. In either case, illumination is carried on a fiber optic bundle to the distal end of the insertion tube to illuminate the remote target. Also, in either case, sensitive and delicate focussing optics are carried at the distal tip. A steering mechanism, which can be a stack of disks separated by beads or spacers, articulates the distal end of the insertion tube for purposes of steering and positioning of the imaging device. Steering cables within the insertion tube connect the steering section with a control section at the proximal end.
For purposes of transport or storage between uses, the borescope insertion tube is stored in a box or case filled with open cell or closed cell foam padding. Typically, an annular cutout is formed in the foam, and the insertion tube is laid in the cutout for storage. Other parts of the borescope are stored in other recesses and receptacles in the foam filling. Then, the lid of the case is closed, and the delicate parts of the insertion tube are protected from abuse or shock. However, in some cases, the insertion tube is not completely contained within the case when the lid is shut. If part of the insertion tube extends over the lip of the case when the lid is closed, the sheath of the insertion tube can be inadvertently crushed when the user closes the case. This damage often requires expensive repairs, which must be conducted at the factory. The numerous cables, fiber optic bundles, optics, and electrical conductors can be damaged or severed if the insertion tube is not properly positioned in the foam padding when the lid is closed.

Case for flexible borescope and endoscope insertion tubes


A fuel cell stack comprises a plurality of planar fuel cells in a spiral configuration. The fuel cells angularly offset from one another such that immediately adjacent cells only partially overlap one another. The cells are preferably of the unitized type. A manifold assembly is operatively adjacent to the fuel cells. The manifold assembly includes an inlet manifold and an outlet manifold for each of the gases that are in communication with the fuel cells.

The present invention generally relates to planar, solid oxide fuel cells and, more particularly, to an apparatus and method of stacking and manifolding unitized solid oxide fuel cells for ready connection and disconnection of gases to manifolds.
A fuel cell is basically a galvanic conversion device that electrochemically reacts a fuel with an oxidant within catalytic confines to generate a direct current. A fuel cell typically includes a cathode material that defines a passageway for the oxidant and an anode material that defines a passageway for the fuel. An electrolyte is sandwiched between and separates the cathode and anode materials. An individual electrochemical cell usually generates a relatively small voltage. Thus, to achieve higher voltages that are useful, the individual electrochemical cells are connected together in series to form a stack. Electrical connection between cells is achieved by the use of an electrical interconnect between the cathode and anode of adjacent cells. Also typically included in the stack are ducts or manifolding to conduct the fuel and oxidant into and out of the stack.
The fuel and oxidant fluids are usually gases and are continuously passed through separate cell passageways. Electrochemical conversion occurs at or near the three-phase boundary of the gas, the electrodes (cathode and anode) and electrolyte. The fuel is electrochemically reacted with the oxidant to produce a DC electrical output. The anode or fuel electrode enhances the rate at which electrochemical reactions occur on the fuel side. The cathode or oxidant electrode functions similarly on the oxidant side.
Specifically, in a solid oxide fuel cell (SOFC), the fuel reacts with oxide ions on the anode to produce electrons and water, the latter of which is removed in the fuel flow stream. The oxygen reacts with the electrons on the cathode surface to form oxide ions that are conducted through the electrolyte to the anode. The electrons flow from the anode through an external circuit and then to the cathode. The circuit is closed internally by the transport of oxide ions through the electrolyte.
In a SOFC, the electrolyte is in a solid form. Typically, the electrolyte is made of a nonmetallic ceramic, such as dense yttria-stabilized zirconia (YSZ) ceramic, that is a nonconductor of electrons which ensures that the electrons must pass through the external circuit to do useful work. As such, the electrolyte isolates the fuel and oxidant gases from one another and allows a potential to build up across it as a result of the difference in electrochemical potential between the fuel and the oxidant. The anode and cathode are generally porous, with the anode oftentimes being made of nickel/YSZ cermet and the cathode oftentimes being made of doped lanthanum manganite. In the solid oxide fuel cell, hydrogen or a hydrocarbon is commonly used as the fuel, while oxygen or air is used as the oxidant.
As mentioned above, the voltage output of a single fuel cell is far too low for many applications. Thus, it frequently becomes necessary to connect multiple fuel cells in series to obtain high voltage power. Additionally, the power demands of many systems require that fuel cells frequently be connected in electrically parallel circuits, thereby providing a greater total current. The physical stacking of multiple fuel cells in series, parallel or series/parallel configuration, however, must incorporate gas-tight connections to allow for a safe and efficient flow of reaction gases. Typically, a group of individual fuel cells are welded, soldered or otherwise bonded together into a single unitary stack, thereby preventing the improper mixing of the reaction gasses, such as in U.S. Pat. No. 5,861,221.
For any given cell, defects can occur during processing. A cell can also become damaged during handling. Because some defects may have been undetected, their negative affects, such as poor performance and consequent effects on its neighboring cells or even the entire stack, are not realized until the cell is placed in the stack. Where adjacent cells are fused or bonded together into a single unitary stack, a single cell that is defectively formed cannot be removed and interchanged with a non-defective cell. At best, the performance of the fuel cell stack becomes impaired. At worst, the entire stack must be discarded due to the failure of a single cell.
In addressing the above drawbacks, the assignee of the present invention has developed a unitized fuel cell that is the subject of U.S. patent application Ser. No. 09/419,343 filed Oct. 15, 1999. The unitized cell includes a first electrically conductive interconnect operatively connected to an anode of the fuel cell. The first interconnect has a first substantially planar portion and a first skirt portion. A second electrically conductive interconnect is operatively connected to a cathode of the fuel cell. The second interconnect has a second substantially planar portion and a second skirt portion, with the second skirt portion being juxtaposed to the first skirt portion. A first salient is formed by a portion of at least one of the first and second skirt portions, with the first salient being disposed at a first edge of the fuel cell. A second salient is formed by a portion of at least one of the first and second skirt portions, with the second salient being disposed at a second edge of the fuel cell. An insulating gasket is disposed between the first and second skirt portions and against the ceramic cell to seal the gases within their respective cell housings. The first and second salients can be attached to a gas manifold by attaching a tube to the skirt of the metal housing. Thus, the fuel cell can be electrically connected with other fuel cells in series and parallel configurations through contacts between metal housings and/or through metal gas manifold tubings. A series connection is made when the anode interconnect of one cell is made in contact with the cathode of its adjacent cell whereas a parallel connection can be made if a metal gas tubing is used to electrically connect similar electrodes of two different cells.
While the use of unitized fuel cells solves many drawbacks in the prior art, design issues relating to the actual stacking and manifolding of fuel cells remain. For example, U.S. Pat. No. 5,298,341 describes prior art as including fuel cell stacks that are arranged in a block configuration. With the stacks positioned adjacent to one another, a manifold is attached to all gas channels of the same orientation. Another prior art design is described as manifolding each stack individually. However, both prior art designs are described as having numerous disadvantages. Thus, U.S. Pat. No. 5,298,341 provides a module having stacks of fuel cells. The fuel cells in each stack are arranged to provide an overall rectangular configuration to the stack. The stacks are oriented on edge and radially spaced apart around a central plenum. The fuel cells in the stacks have gas passageways that extend parallel and perpendicular to the longitudinal axis of the plenum. Circular manifold plates are positioned above and below the module. Each plate has gas flow apertures that coincide with the position of the stacks and a plenum aperture that coincides with the position of the central plenum. In this design, individual stacks may be replaced or repaired but it will be difficult to remove individual cells without affecting the integrity of the neighboring cells.
In U.S. Pat. No. 4,048,385, manifolding is directed to planar, cylindrical shaped fuel cells. The cells include a central active portion surrounded by a frame portion. The frame portions contain duct openings so that when the cells are in a stack, the combined frame portions provide channels extending parallel to the longitudinal axis of the stack. The channels provide inlet and outlet means for different gases. Hollowed out portions in the frame portions allow the passage of gases between the channels and active portions. End plates are then used to sandwich the above components. In this design, holes around the perimeter of the cell can become weak spots that may cause the cell to fracture when placed under the stress of a stack assembly.
Another example of manifolding is in U.S. Pat. No. 4,876,163 that discloses tubular shaped fuel cells with their longitudinal axes aligned parallel to one another. Having such parallel orientation, the fuel cells are arranged in either concentric circles, a spiral, or folded rows. Manifolds are located at the distal ends of the cells. The arrangement was intended to reduce the flow of heat from an interior location of the fuel cell stack to a peripheral location. It was also intended to enable series connection. This design, while being applicable to tubular cells, is not applicable to planar cells.
As can be seen, there is a need for an improved solid oxide fuel cell stack and method of stacking such cells. Another need is for a planar, solid oxide fuel cell stack that provides improved stacking and manifolding. A further need is for a stack design that incorporates unitized fuel cells. Also needed is a fuel cell stack design that minimizes the footprint of the stack. Yet another need is for a fuel cell stack design that allows easy connection and disconnection of gases to the stack.
In one aspect of the present invention, a fuel cell stack comprises a plurality of planar fuel cells juxtaposed to and angularly offset from one another; and a manifold assembly operatively adjacent to the fuel cells, with the manifold assembly being in gas communication with each of the fuel cells.
In another aspect of the present invention, a method of forming a fuel cell stack comprises juxtaposing a plurality of planar fuel cells to one another, with the fuel cells having a pair of planar interconnects that sandwich an anode, cathode, and electrolyte therebetween; orienting the fuel cells in a spiral configuration; interfacing a manifold assembly to the fuel cells; and placing each of the fuel cells in gas communication with the manifold assembly.
These and other features, aspects and advantages of the present invention will become better understood with reference to the following drawings, description and claims.

Stacking and manifolding of angularly offset, unitized solid oxide fuel cells


A disk cartridge includes a lower case having an opening formed thereon, an upper case installed at the lower case to be capable of being open and shut while pivoting, to accommodate a disk therebetween, a shutter installed at the lower case to be capable of sliding and opening and shutting the opening hole, a close covering member having an inclined surface installed at the shutter to be capable of sliding, closely contacting a non-information area disposed at an inner circumference of the disk when the shutter is closed, and being separated from the non-information area disposed at the inner circumference of the disk when the shutter is open. Thus, when the shutter is closed, introduction of dust is prevented so that the possibility of the information area of the disk being contaminated is lowered. Also, since the disk is fixed between the upper and lower cases, while the disk is carried, noise and damage can be reduced.

1. Field of the Invention
The present invention relates to a disk cartridge protecting a recording surface of an accommodated disk that is an information recording/reproduction medium, from contaminants, such as dust or a fingerprint.
2. Description of the Related Art
In general, a disk cartridge accommodates a disk that is an information recording/reproduction medium and is installed in a disk drive. As shown in FIG. 1, a conventional disk cartridge 100 includes a case 101 accommodating a disk D, a shutter 110 installed in the case 101 to be capable of rotating to selectively open and shut an opening 102 formed on the case 101 so that a pickup (not shown) of a disk drive can access the disk D, and a cover 103 fixed on an upper portion of the case 101. The disk cartridge 100 further includes a hole 103 formed on the cover 103 for disk exchange and clamping, and an escape prevention lever 103a installed at the cover 103 to be capable of sliding to prevent the disk D from escaping through the hole 103b. Thus, when the disk D is installed, the escape prevention lever 103a is pulled back not to interfere with the disk D. After the disk installation is completed, the escape prevention lever 103a is pushed forward so that an end portion of the escape prevention lever 103a prevents the disk D from escaping through the hole 103b.
When the disk cartridge 100 accommodating the disk D is inserted into the disk drive, as shown in FIG. 2A, an opening lever 120 installed at the disk drive pushes a locking piece 111a so that a protrusion 111c of the shutter 110 is unlocked from a groove 101a of the case 101. Then, the opening lever 120 pushes an interference piece 111b to have the shutter 110 pivot with respect to the case 101. The shutter 110 includes first and second shutter portions 111 and 112 respectively installed to pivot around left and right pivot shafts 110a and engaging each other through an engagement gear portion 113. As the first shutter portion 111 incorporated with the interference piece 111b rotates clockwise, the second shutter portion 112 rotates counterclockwise so that the first and second shutter portions 111 and 112 are separated from each other to open the opening 102. Then, a turntable (not shown) and a damper (not shown) of the disk drive pass through the opening 102 and the hole 103a, respectively, to clamp the disk D. A pickup (not shown) accesses a recording surface (information area) of the disk D to perform an information recording and/or reproducing process. Although not shown in FIGS. 1 through 2B, a torsion spring elastically biasing the first shutter portion 111 in a counterclockwise direction on FIGS. 1 through 2B, that is, in a direction to close the opening 102, is installed between the first shutter portion 111 and a bottom surface of the case 101. When a force applied by the opening lever 120 is removed, the shutter 110 is returned to an original closed position.
However, in the above structure, since the shutter 110 is installed in the case 101, and the disk D is placed on the shutter 110, during an opening/shutting operation of the shutter 110, the shutter 110 contacts the recording surface of the disk D (a lower surface of a disk in the drawings) so that the recording surface of the disk D may be scratched by the shutter 110 to be damaged.
Also, dust can be introduced through the hole 103b of the cover 103. Of course, since an upper surface of the disk D facing the hole 103b is not a surface for recording, direct contamination due to the dust does not occur. Nonetheless, as the dust is introduced into the case 101 and placed on the shutter 110, the dust on the shutter 110 adheres to the recording surface of the disk D during the opening/shutting operation. Therefore, an improved structure to protect the information area of the disk D is needed.

Disk cartridge to protect an information area of a disk from being contaminated

Matsushita Electric Industrial Co., Ltd.


Systems and methods are described for generating automatic illustrator guides. The method may include generating a plurality of candidate guides for a digital image (e.g., using an automated shape detection engine), where each of the plurality of candidate guides is a simple shape such as a line or a circle, combining at least two of the candidate guides based on the shape information to create refined candidate guides, generating a pixel coverage map for each of the refined candidate guides, prioritizing the refined candidate guides based on the corresponding pixel coverage maps, selecting one or more drawing guides from the one or more refined candidate guides based on the prioritization, and displaying the digital image along with the one or more drawing guides.

The following relates generally to generating drawing guides, and more specifically to automatically generating illustrator guides based on a rough sketch.
Many people draw hand sketches either for business or personal enjoyment. In many cases, these sketches are either made with the help of a digital device, or imported into a digital device for editing. The process of digitizing an image may either be done manually, or with an automatic tool. The digitized image may be in the form of two-dimensional vector graphics, which are defined in terms of points connected by lines and curves to form polygons and other shapes.
In some cases, digitizing a hand sketched image results in a large number of points (i.e., anchor points), which may make it difficult and time consuming to edit the drawing. For example, to edit the drawing may require manually editing a very large number of independent points.


A high-Si content austenitic stainless steel, which exhibits stable acid resistance and excellent corrosion resistance in high-temperature and concentrated nitric acid, has a chemical composition comprising: C: at most 0.04%; Si: 2.5-7.0%; Mn: at most 10%; P at most 0.03%; S: at most 0.03%; N: at most 0.035%; sol. Al: at most 0.03%; Cr: 7-20%; Ni: 10-22%; optionally, one or more types selected from Nb, Ti, Ta and Zr: 0.05-0.7% in total; and the remainder being Fe and impurities, wherein a total amount of B1 type inclusions measured by a method according to JIS G0555 (2003) Annex 1 “Microscopic Testing for the Non-Metallic Inclusions on the Point Counting Principle” is not more than 0.03% by area %.

Stainless steel forms a stable passive film in nitric acid thereby exhibiting excellent corrosion resistance. However, high-temperature and concentrated nitric acid, for example, a temperature of 80 to 90° C. and a concentration of 90% by mass, has an extremely strong oxidizing power and causes transpassive corrosion in general stainless steels. Further, transpassive corrosion facilitates general corrosion in whole, which involves dissolution of Cr2O3 which forms a passive film.
An example of materials having corrosion resistance in this type of environment includes high-Si austenitic stainless steels disclosed by Patent Documents 1 and 2. These high-Si austenitic stainless steels have excellent nitric acid corrosion resistance due to formation of a silicate (SiO2) film in a transpassive region.
However, regarding acid resistance, although no serious problem has occurred, there are cases where corrosion is excessively facilitated, the causes of which are unclear in many respects, and a solution for such cases is needed.
Moreover, in a high-Si austenitic stainless steel, because of a concentration of Si, a large amount of inclusions and intermetallic compounds are formed in steel, causing deterioration of hot workability. To solve this problem, Patent Document 3 discloses that hot workability is improved by limiting the chemical composition such that Al is 0.05% or less ("%" regarding chemical composition means "mass %" unless otherwise stated in the present description) and O is 0.003% or less, and by eliminating formed intermetallic compounds through hot rolling after performing soaking and/or temperature uniformity at 1100 to 1250° C. for long hours. The inclusions are limited in the total amount, and not limited in their types.
Although Patent Document 4 discloses defining an amount of sol. Al to prevent the production of oxides which deteriorate corrosion resistance in working-flow, it has given no consideration on inclusions produced in molten steel, and is silent on the deterioration of corrosion resistance caused by inclusions. Since in general, the amount of inclusions such as Al2O3 is not directly related to the amount of sol. Al, simply controlling the amount of sol. Al is not enough to prevent problems caused by inclusions.
Patent Document 5 discloses that corrosion resistance is improved by finely dispersing inclusions based on the idea that inclusions originally occurs corrosion. However, it only facilities fine dispersion of MnS by controlling the amount of S and hot rolling conditions, and discloses nothing on alumina inclusions and others.
Patent Document 6 discloses an invention to prevent pitting corrosion by making a cluster of inclusions granular to make the inclusions water insoluble through the control of the composition of the inclusions. However, such inclusions hinder the formation of a silicate film which is needed to improve corrosion resistance under high-temperature and concentrated nitric acid.

Method for manufacturing high-Si austenitic stainless steel

NIPPON STEEL & SUMITOMO METAL CORPORATION


A fishing reel has a frame and a line spool rotatably mounted therein. The frame has a side plate with a circumferential flange formed with a circumferentially directed slot. A buzzer meachnism is mounted in the fishing reel. The buzzer mechanism has a gear wheel non-rotatably connected to the line spool, a trigger mounted on the circumferential flange, and a U-shaped spring leaf, one leg of which is connected to the trigger. The trigger is displaceable along the slot in the circumferential flange between a first position, in which it maintains the other leg of the spring leaf in engagement with the gear wheel so as to produce a buzzing sound when the line spool rotates, and a second position, in which it maintains the other leg of the leaf spring out of engagement with the gear wheel.

The present invention relates to a buzzer mechanism in a fishing reel having a frame, a shaft extending through the frame, and a line spool rotatably mounted on the shaft, said frame having a side plate with an axially directed circumferential flange formed with a circumferentially directed slot.
A known buzzer mechanism for this type of fishing reel has a gear wheel non-rotatably connected to the line spool, resilient means mounted on the frame, and a trigger mounted on the circumferential flange of the side plate and having a substantially radial projection extending into the side plate through the slot in the circumferential flange, said trigger being displaceable along said slot between a first position, in which it maintains the resilient means in engagement with the gear wheel to produce a buzzing sound when the line spool rotates, and a second position, in which it maintains the resilient means out of engagement with the gear wheel.
In this known buzzer mechanism, the trigger is retained on the circumferential flange of the side plate by means of a spring leaf engaging the inner side of the circumferential flange and having a hole through which the projection of the trigger extends. The spring leaf is fixed on the projection of the trigger by means of a pin extending through the projection. The resilient means consists of a mounting plate, an actuator pin which extends through a slot in the mounting plate and is displaceable between two end positions in this slot, a buzzer pawl mounted on the actuator pin by means of a locking washer and adapted to cooperate with the gear wheel, and two springs mounted between the mounting plate and the buzzer pawl for maintaining the actuator pin in one end position. The projection of the trigger is designed for cooperation with the actuator pin in such a manner that, when the trigger is moved from its second position to its first position, the trigger projection urges the buzzer pawl, by the intermediary of the actuator pin and against the action of the springs, to a position in which the buzzer pawl engages the gear wheel for providing the buzzer function.
This known buzzer mechanism thus consists of a large number of components, making it difficult to mount.


A process is provided to trimerize or oligomerize olefins in the presence of an olefin oligomerization catalyst and a solvent which is a product of the olefin oligomerization process.

This invention relates to olefin production.
Olefins, primarily alpha-olefins, have many uses. For example, alpha-olefins, such as 1-hexene, can be used in hydroformulation (OXO processes). In addition to uses as specific chemicals, alpha-olefins can be used in polymerization processes as either a monomer or comonomer to prepare polyolefins, or polymers. Often the production of olefins is carried out in the presence of a solvent, or a diluent. Unfortunately the presence of such a solvent or diluent complicates an olefin production process by requiring the presence of an additional chemical, i.e., the solvent, which therefore necessitates piping and control systems for the solvent. Additional processing step(s) in order to separate the desired olefin product from the solvent, as well as solvent recovery and/or disposal, also can be necessary.


A waterproof and vapor-permeable shoe, comprising a sole, provided with a vapor permeation region, an assembly insole, which is covered, toward the sole, by at least one first gasket made of waterproof material, which has at least one vapor-permeable or perforated portion above the vapor permeation region, which, once assembled, covers an upper shoe assembly, which comprises at least one vapor-permeable lining, a vapor-permeable upper, and a waterproof and vapor-permeable upper membrane that is between them, the upper shoe assembly being associated with the assembly insole, and at least one second gasket, which adheres so to form a waterproof seal to the first gasket and is glued to the lower edge of the upper, the second gasket forming a waterproof sealing region of the upper shoe assembly and the first gasket to the sole.

It is known that the comfort of a shoe is linked not only to its anatomically fitting properties but also to the capacity to dissipate outward the water vapor that forms inside the shoe due to sweating.
For this reason, waterproof shoes with an upper coupled to a lining that is laminated with a waterproof and vapor-permeable membrane have now been known for years.
The expression "waterproof and vapor-permeable" generally references the characteristic of tightness to water in the liquid state combined with permeability to water vapor.
The portion of the foot that notoriously has the greatest perspiration effect is the sole, and the sweat that it generates saturates the air with moisture and mostly condenses, stagnating on the footbed.
Only a marginal fraction of the moisture produced by sweating is diffused to the sides of the upper and exits from them if they are vapor-permeable.
In order to allow easy dissipation of the sweat that tends to accumulate in the region of the sole, shoes are currently known which have different types of rubber soles that are impermeable to water in the liquid state and are permeable to water vapor and are obtained by using a vapor-permeable and waterproof membrane, which is sealed to the body of the sole so as to cover through openings thereof.
The production method commonly known as "AGO lasting" has long been known in the shoe manufacturing field and provides, with an operation known as lasting, for pulling the upper shoe assembly onto the last, folding its lower edges, known as lasting margins, under an insole, to which they are glued perimetrically, so as to interpose themselves partially between said insole and the sole that will be assembled thereon.
Assembling the sole consists in joining the sole to the upper portion of the shoe, by gluing or by direct injection in a mold.
So-called "AGO lasting" construction is generally used for shoes of the type generally classified as classic or elegant.
Stretching the upper and the lining on the last in fact allows to make them adhere thereto precisely, achieving effective formation.
The assembly insole is made of a flexible material that however is structured enough to not undergo deformation due to the traction applied thereto by the lasting margins glued onto it during lasting.
Currently it is known that even when the upper shoe assembly has a waterproof and vapor-permeable membrane, inserted between the outer layer of the upper and the inner lining without additional refinements, then there is a substantially total lack of waterproofing.
The "AGO lasting" construction, in the way it is currently performed, in fact allows penetration of water toward the inside of the shoe through the outer layer of the upper and through the insole.
A need that is particularly felt in the manufacture of shoes with a waterproof and vapor-permeable membrane, in the upper shoe assembly, consists in achieving an effective seal of the joining regions between the insole, the lining with membrane, the outer layer of the upper and sole, in order to avoid even the slightest infiltration of water from outside.
It is in fact particularly difficult to seal the sole to said membrane, since in so-called "AGO lasting" construction the bottom of the shoe is not smooth and flat, as occurs for example in the case of "Strobel" construction, in which the edges of the insole are sewn to the edges of the upper or of the lining laminated with the membrane, but the lasting margins of the upper are superimposed on the assembly insole, creating irregularities along its perimeter.
In particular, the creases produced as a consequence of the assembly of the toe and heel of the upper onto the assembly insole constitute actual channels for water infiltration.
However, it is not possible to remove these protrusions by means of the common operation of roughing the upper with steel brushes, since this operation might damage the waterproof and vapor-permeable membrane inserted between the upper and the lining.
Accordingly, as described for example in patent application WO 9316612, shoes have now been studied for years which have a waterproof and vapor-permeable insole which comprises a waterproof and vapor-permeable membrane with which the lasting margins of a lining with a waterproof and vapor-permeable membrane are associated by means of a first lasting operation.
The joining region between the lining with the membrane and the insole is sealed by means of a waterproof sealing tape.
The lasting margins of the outer layer of the upper are then associated, by means of a second lasting operation, with the waterproof and vapor-permeable insole.
The embodiment is not free from aspects that can be improved, since the water absorbed by the outer layer of the upper and wicked inside it can stagnate below the waterproof insole.
Moreover, this construction has an additional drawback if a sole provided with openings is used, since water might enter through said openings and wet the lasting margins of the upper, impregnating it and thus rising toward the foot insertion region.
Moreover, the use of a waterproof and vapor-permeable membrane that covers the entire surface of the insole, if the vapor-permeable surface of the sole does not extend over its entire longitudinal direction, is useless and very expensive.
An alternative to the use of a waterproof and vapor-permeable insole is described in U.S. Pat. No. 5,426,869, in which a waterproof layer acting as a gasket is provided by a non-woven polyester fabric that is uniformly coated on one of its faces with a layer of adhesive based on polycaprolactone. This waterproof gasket is used to fill the area comprised transversely between the lasting margins of the lining or upper, if they are waterproof and vapor-permeable, and constitutes a waterproof layer between the insole and the sole.
Since the gasket is made of waterproof and non-vapor-permeable material, this construction is unsuitable with a rubber sole rendered impermeable to water in the liquid state and permeable to water vapor by means of regions that are open or perforated and are covered and sealed with a waterproof and vapor-permeable membrane.
Moreover, if the gasket is pierced at the vapor-permeable area of the sole, in order to allow the outflow of the water vapor generated by sweating, the lasting margins of the outer layer of the upper would wick, toward the inside of the shoe, the water, which would migrate onto the insole indeed through the holes in the gasket.
An alternative to these solutions is to use a lining with a waterproof and vapor-permeable membrane that is closed like a sock, so as to wrap around the foot completely.
An insole is applied to the bottom of the sock and the lasting margins of the outer layer of the upper are folded and glued onto it perimetrically.
The sock-like lining comprises an opening for the foot and is generally formed by two lateral portions and a lower portion, the connection of which is provided by means of zigzag and/or Strobel seams and sealed by means of waterproof sealant tape.
It is well-known that this production method is very complicated and delicate.
Moreover, precise shaping of the sock closed by means of seams and not by lasting on a last is difficult to achieve, both due to difficulty in preparing the various components that must be cut and sewn with accurate precision and due to difficulty in achieving correct tension, without creases, between the upper and the lining.
Indeed, due to the fact that during the sewing of the lining the last is not used, said lining tends to wrinkle during the lasting of the upper, contrary to what instead occurs when one uses "AGO lasting" construction, which allows to obtain an upper and a lining that are correctly formed, stretched and smooth.


A process for the preparation of toner comprising. (i) preparing, or providing an aqueous colorant dispersion, which dispersion is comprised of a colorant and an ionic surfactant in water; PA1 (ii) blending said colorant dispersion with a latex emulsion comprised of resin particles, a nonionic surfactant, and an ionic surfactant of opposite charge polarity to that of the ionic surfactant in said colorant dispersion; PA1 (iii) heating the resulting mixture below about the glass transition temperature (Tg) of the latex resin to form toner sized aggregates; PA1 (iv) heating the resulting aggregate suspension of (iii) above about the Tg of the latex resin; and PA1 (v) retaining the temperature in the range of from about 30.degree. C. to about 95.degree. C., and subsequently, adding an aqueous solution of boric acid, or an aqueous solution of a metal salt; adjusting the pH of the resulting reaction mixture to from about 9 to about 12 by the addition of a base, followed by the addition of a salicylic acid or catechol; and optionally PA1 (vi) isolating, washing and drying the toner obtained.

The present invention is generally directed to toner processes, and more specifically, to chemical processes which involve the aggregation and fusion of latex, colorant, such as pigment, and additive particles into toner particles, and wherein certain charge enhancing entities, or agents are generated in situ and are chemically bound to the surface of the toners obtained. In embodiments, the present invention is directed to chemical processes for obtaining toners wherein the toner surface is chemically modified to provide suitable charging characteristics, and in embodiments toner compositions with a volume average diameter of from about 1 to about 15 microns, and preferably from about 2 to about 10 microns with a narrow particle size distribution as conventionally characterized by GSD of, for example, less than or equal to about 1.35, and preferably less than about 1.25, and more specifically, from about 1.13 to about 1.25 as measured on the Coulter Counter. The resulting toners can be selected for known electrophotographic imaging and printing processes, including digital color processes. In embodiments, with the processes of the present invention there are chemically bonded to the toner charge enhancing additive components, and thereby for example, the movement or migration of these components is eliminated, or minimized. The chemically bonding, or attachment can be achieved, for example, by the reaction of a carboxylic acid group, such as the carboxylic acid group of a poly(acrylic acid) or its copolymer with an appropriate charge enhancing additive precursor.


The invention relates to a device (1) for use in collection and removal of slurry or similar from a sty, a sty comprising such a device and to a method of installing a device at a sty, such as a pig sty, wherein the device comprises an one-piece body (2) having one or more funnels (3) wherein each funnel comprises at least one upper opening (3a) having an upper horizontal area enclosed by an upper edge (3a′) and a lower opening (3b) having a lower horizontal area enclosed by a lower edge (3b′), wherein the upper horizontal area is larger than the lower horizontal area, and the inside (3′) of the funnel is thus extending from the upper opening to the lower opening of the funnel, an encapsulation (4) enclosing the funnel from the lower edge of the funnel to the upper edge of the funnel, such that a ventilation space (5) is defined within the one-piece body between the encapsulation and the funnel.

In this disclosure slurry is defined as all kinds of animal waste such as excrements, faeces, urine, manure and left over litter, animal feed, water etc. It is generally preferred that slurry is at least partially removed, from the sty in order to maintain a reasonable level of hygiene and to reduce the concentration of polluting element in the air in particularly of evaporated ammonia.
Within animal production, especially within pig farming, it is desired to produce a system which effectively removes slurry from the sty, improves the air quality within the sty and which at the same time is cheap to produce, easy to install and environment-friendly.
Traditional devices used for collection and removal of slurry mainly comprise openings such as pits under the floor level of the sty, wherein the slurry is collected and led away. The slurry may be located in these pits for a long period of time and these open pits provide a large surface area and usually result in a high level of slurry evaporation, causing high level ammonia in the air. Furthermore the reduced amount of nitrogen in the slurry causes it to have reduced fertilizing properties. The pits are usually covered by grid floor, making it difficult to provide the sty with straw, whereby the wellbeing of the pigs is decreased. Presently, it is therefore required that at least some of the floor in a pig sty is a solid floor and only ⅓ of the sty area comprises a grid floor.
The system described in the document DK 176179 B1 seek to improve the air quality within the sty. The document describes a system comprising a number of funnels. The pyramid shape of the funnel reduces the surface area of the slurry when located in the funnel compared to using a traditional slurry pit. The pyramid shape also promotes a faster transportation of the slurry to a pipe system in the floor of the pit. Furthermore the funnel is made of HDPE plastic, providing a low friction force on the slurry, further promoting a faster removal of the slurry. The funnels are connected to the pipe system through protruding pipe sections in the floor of the pit. The device is therefore assembled in the pit. Two rows of funnels are usually installed together, with a space between them which is used as a ventilation space. For that purpose, an opening in one side of the funnel is provided, through which air can flow. The funnels are supported by using support legs and by resting the funnel up against one of the side walls of the pit.
One object of the invention is to provide a device and a sty with the device which comprises means for optimum and effective collection and discharge of slurry from the sty. A second object of the invention is to improve the air quality within the sty and reduce the amount of ammonia evaporated into the air. Another object of the present invention is to provide a device and a sty with a device which has a more compact and simplistic design, which reduces the material, fabrication and installation costs. A further object is to provide a device and a sty with the device which can be prefabricated and installed as ready-made device, thereby minimizing the amount of elements which needs assembling upon installation. An object of the present invention is also to provide a device of high quality, which is durable and self-supported.

Device for collection and removal of slurry


A d.c. voltage is supplied to an inverter power source to drive a light source. Light from the light source is directed uniformly from the back side of a liquid crystal panel. When an image is displayed on the liquid crystal panel during a display period and a position detection pen is in close proximity to the liquid crystal panel at a position detection period, coordinates are calculated according to an induced voltage by the position detection pen and the timing of applying a scanning voltage to an electrode of the liquid crystal panel. The driving of the light source by the inverter power source is suspended or reduced during the position detection period, so that noise from the inverter power source is prevented from being mixed into the position detection pen.

1. Field of the Invention
The present invention relates to coordinate input devices. More particularly, the present invention relates to a coordinate input device including a back light such as an electrostatic capacitance system or electromagnetic induction system tablet.
2. Description of Background Art
FIG. 7 shows an appearance of a conventional Japanese word processor that allows coordinate input, and FIG. 8 is a perspective view of the conventional word processor of FIG. 7 showing the structure of a display unit thereof.
Referring to FIG. 7, a Japanese word processor includes a lower cabinet 1 and an upper cabinet 2. The lower cabinet 1 includes a floppy disc drive 3. The upper cabinet 2 includes a display unit 4, a printer 5, a pen 6, a keyboard 7, and a ten-key light receiving unit 8. The pen 6 serves to detect a coordinate position on the display unit 4.
Referring to FIG. 8, the display unit 4 includes a display cabinet 41 in which the pen 6 can be placed, a liquid crystal unit 42, and a back light unit 43. The back light unit 43 has lamp holders 44 and 44' provided at the top portion and the bottom portion, respectively, with a light-guiding plate 45 provided therebetween. An inverter 46 is provided at the left side of the back light unit 43. The inverter 46 oscillates a high voltage to drive a lamp (not shown) held by lamp holder 44. Light from this lamp is directed from beneath the liquid crystal 42 by the light-guiding plate 45.
FIG. 9 is a block diagram of a coordinate input device for driving the display unit of FIG. 8 and for detecting a coordinate position indicated by the pen. FIG. 10 is a timing chart showing the periods of the liquid crystal unit display and coordinate detection according to the circuitry shown in FIG. 9.
The electrical configuration of the coordinate input device will be described hereinafter. Referring to FIG. 9, the liquid crystal unit 42 is formed with a liquid crystal layer between common electrodes Y1-Yn (referred to as "Y" hereinafter) and segment electrodes X1-Xm (referred to as "X" hereinafter). The portion of the liquid crystal where each common electrode Y and each segment electrode X cross each other is a pixel. The common electrodes Y are driven by a common driving circuit 22. The segment electrode X is driven by a segment driving circuit 23. The common driving circuit 22 and the segment driving circuit 23 are connected to a display control circuit 25 and a position detection control circuit 26 via a switching circuit 24. The switching circuit 24 is controlled by a control circuit 27 to provide an output from the display control circuit 25 during a display period and an output from the position detection control circuit 26 during a position detection period to driving circuits 22 and 23.
During a display period, the display control circuit 25 provides a start signal S, and an inversion signal M, clock signals CP1 and CP2, and display data DO--D3. The scanning period for scanning pixels of one row is the cycle of the clock signal CP1. The clock signal CP1 is applied to the common driving circuit 22 and the segment driving circuit 23 via the switching circuit 24. The start signal S indicates the start of a scanning period for display. The start signal S is provided from the switching circuit 24 to be applied to the common driving circuit 22 in synchronization with the clock signal CP1.
In response to a shift of the clock signal CP1, a driving signal is provided to the common electrodes Y from an output terminal of the common driving circuit 22 corresponding to the shift position. This driving signal is produced according to bias voltages V0-V5 supplied from the power source circuit 32. The scanning period for scanning one column of pixels is divided into a plurality of periods, which is one cycle of the clock signal CP2. The clock signal CP2 is provided via the switching circuit 24 to be applied to the segment driving circuit 23.
Display data D0-D3 are output via the switching circuit 24 to be applied to the segment driving circuit 23 to be sequentially fetched into a register therein. When display data corresponding to one row of pixels are fetched, these display data are latched at the timing of the clock signal CP1, whereby a driving signal corresponding to each display datum is output from an output terminal of the segment driving circuit 23 to segment electrodes X. This driving signal is produced according to bias voltages V0-V5 supplied from the power source circuit 32. The inversion signal M cyclically inverts the polarity of the voltage applied to the liquid crystal to prevent degradation of the liquid crystal caused by the hysteresis.
Pixels of the liquid crystal panel 42 are driven according to their respective row sequence by operations of the common driving circuit 22 and the segment driving circuit 23, whereby a pixel corresponding to the display data is displayed on the liquid crystal panel 42.
During a coordinate detection period, the position detection control circuit 26 provides a start signal Sd, an inversion signal Md, clock signals CP1d and CP2d, and driving data D0d-D3d. The scanning period for scanning one row of common electrodes Y is the cycle of the clock signal CP1d. The clock signal CP1d is applied to the common driving circuit 22 and the segment driving circuit 23 via the switching circuit 24. The start signal Sd indicates start of scanning of common electrodes Y. The start signal Sd is provided via the switching circuit 24 to be applied to the common driving circuit 22 in synchronization with the clock signal CP1d. In response to a shift of the clock signal CP1d, a scanning signal is provided to common electrodes Y from an output terminal of the common driving circuit 22 corresponding to the shift position. This scanning signal is produced according to bias voltages V0-V5 supplied from the power source circuit 32.
The scanning period for scanning one column of segment electrodes X is the cycle for the clock signal CP2d. The clock signal CP2d is applied form the switching circuit 24 to the segment driving circuit 23. Driving data D0d-D3d provided via the switching circuit 24 are applied to the segment driving circuit 23 to be sequentially fetched into an internal register thereof. When driving data corresponding to one row of segment electrodes X are fetched, these driving data are latched a the timing of the clock signal CP1d, whereby a driving signal corresponding to each driving data is provided from an output terminal of the segment driving circuit 23 to segment electrodes X. This driving signal is produced according to bias voltages V0-V5 supplied from the power source circuit 32. The inversion signal Md cyclically quickly inverts the polarity of the voltage applied to the liquid crystal to prevent degradation of the liquid crystal caused by electrolysis.
When the pen 6 approaches the surface of the liquid crystal panel 42, voltage is induced at the electrode of the position detection pen 6 due to a stray capacitance between the electrode provided at the tip of the position detection pen 6 and electrodes X and Y of the liquid crystal panel 42 to which voltages are applied. The voltage induced in the pen 6 is amplified by an amplifier 29 to be applied to an X coordinate detection circuit 30 and a Y coordinate detection circuit 31. The X and Y coordinate detection circuits 30 and 31 calculate the X and Y coordinates, respectively, according to the generation timing of an induced voltage in the pen 6 and a timing signal from the control circuit 27.
FIG. 11 is a diagram for describing a coordinate detection operation by the position detection pen 6.
As described in conjunction with FIG. 9, a detecting electrode of high impedance is provided at the tip of the pen 6. When the pen 6 is in closed proximity to the display surface which is the detection panel surface, a small capacitance is formed between the electrodes of the panel and the pen 6 as shown in FIG. 11(a). When a pulse voltage is applied to the electrode of the panel, a small voltage is induced at the electrode of the pen 6 as shown in FIG. 11(b) by electrostatic induction. Because this induced voltage shows a peak value when a scanning voltage is applied to the electrode right beneath the pen 6, the position of the pen 6 can be identified by sequentially applying a scanning voltage from the edge of the display electrode group to calculate the timing until the peak value is achieved.
The lamp held by the lamp holder 44 of the back light unit 43 is driven by the inverter 46. There is a possibility of erroneous operation in the coordinate detection due to a high voltage generated by the inverter 46 and noise from the inverter to enter from the wiring and the high voltage terminal of the lamp into the tip of the pen 6 to be taken as noise. In order to prevent such erroneous operation, a conductive coating is applied at the hatched outside portion of the lamp holder 44 as shown in FIG. 12 to provide a shield or enclosing the display element side at the high voltage side of the lamp 47 with a shield plate 48 to prevent the tip of the pen 6 from catching noise. The cable connecting the pen 6 with the lamp 29 is shielded.
However, this provision of a shield increases the cost, and complete shielding could not be achieved even if the lamp holder 44 and the inverter 46 are enclosed by a shield plate.

Preventing noise in a coordinate input device by reducing or suspending backlight oscillation voltage


A system for steering a rear wheel of a vehicle having a mechanism for altering a steering ratio, .THETA.S, based on an amount of steering of the rear wheel to an amount of steering a front wheel. The system is disposed in an interconnecting mechanism for mechanically interconnecting the mechanism for steering the front wheel with the mechanism for steering the rear wheel. The value of .THETA.S is set by the following formula: EQU .THETA.S=C1+B.multidot.C3.multidot..vertline.Y.vertline.-C4.multidot..vertl ine.dY.vertline.. where .THETA.S is a steering ratio;. Y is a yaw rate of a vehicle body; PA0 dY is a yaw acceleration of the yaw rate; PA0 C1 is a basic steering characteristic term; PA0 C3 is a yaw rate control gain; PA0 C4 is a yaw acceleration control gain; and PA0 B is a correction coefficient control gain term.. The value of B increases when the amount of steering of the front wheel is small and decreases when the amount of steering of the front wheel is large.

1. Field of the Invention
The present invention relates to a system for steering rear wheels of an automotive vehicle and, more particularly, to a system for steering rear wheels so adapted as to steer front wheels as well as rear wheels.
2. Description of the Related Art
Among systems for steering rear wheels, there is known of such a type as electrically steering the rear wheels completely without mechanical interconnections between a mechanism for steering the rear wheels and a mechanism for steering the front wheels, as disclosed in Japanese Patent Laid-open Publication (kokai) No. 57-44,568. Such an electrically interconnecting type of the system for steering the rear wheels can offer the advantage that the rear wheels can be steered even if the front wheels are sustained in the neutral position, however, it suffers from the disadvantage that it is difficult to set the rear wheels strictly in the neutral position as the front wheels are sustained in the neutral position. Further, such a system may be likely to provide the operator with feeling of uneasiness when the rear wheels are steered in a careless manner in a state in which the front wheels are sustained in the neutral position. In addition, the system has the defect that a sufficient extent of fail measures should be taken at the time of failure.
The above-specified prior patent publication discloses steering characteristics, including a characteristic term for a yaw rate that functions as acting in the direction of converging the yaw rate, if occurred, that is, that functions as an ingredient for correcting a same phase amount in the direction of increasing.
On the other hand, Japanese Patent Laid-open Publication (kokai) No. 62-227,871 discloses a type of mechanically interconnecting a mechanism for steering the rear wheels with a mechanism for steering the front wheels and a steering-ratio altering mechanism is incorporated into such a mechanically interconnecting mechanism. This mechanically interconnecting mechanism can offer the advantage that the rear wheels can be sustained strictly in the neutral position when the front wheels are sustained in the neutral position, however, it suffers from the disadvantage that the rear wheels cannot be steered as long as the front wheels are to be steered.
It is to be noted herein that the rear wheel steering system of the electrically interconnecting type having the characteristic term for the yaw rate as the steering characteristics can negate the yaw rate by steering the rear wheels upon occurrence of the yaw rate due to a side wind during running straight at a high speed, thereby improving stability in running straight.
It is to be noted, however, that the rear wheel steering system of the mechanically interconnecting type having the characteristic term for the yaw rate sustains the rear wheels in the neutral position as long as the front wheels are held in the neutral position, so that the characteristic term for the yaw rate does not substantially serve as improving stability in running straight as long as the vehicle is running straight because the rear wheels cannot be steered even if the yaw rate would be caused to occur due to a side wind.

System for steering rear wheels of an automotive vehicle


According to one embodiment, a method for role determination includes detecting access to sensitive data and determining user information related to the access to sensitive data in response to detecting the access to sensitive data. The method also includes modifying at least one role in response to determining the user information related to the access to sensitive data. In addition, the method includes storing the modified at least one role.

As computing systems become more complex, managing roles in the computing system has become more important. Role-based management provides flexible and secure solutions to access to resources. Developing roles has become problematic due to the proliferation of users of computing systems. Determining what users are associated with particular role(s) is an important problem to solve in order to develop effective role-based management.
A previous solution to this problem includes performing static scans of a computing system in order to determine how usage of the system is organized. This approach is inflexible and insecure because there may be a significant portion of time between the static scans that could lead to security vulnerabilities. For example, a team working on a project may have members added to in-between the static scans; as a result, the new member may not be added to a role until the next scan.